Refine
Is part of the Bibliography
- yes (407)
Year of publication
Document Type
- Journal article (228)
- Doctoral Thesis (156)
- Book article / Book chapter (14)
- Conference Proceeding (6)
- Review (2)
- Preprint (1)
Keywords
- Toxikologie (121)
- DNA damage (18)
- Oxidativer Stress (16)
- micronuclei (13)
- oxidative stress (13)
- Adenosinrezeptor (12)
- DNS-Schädigung (12)
- genotoxicity (12)
- Fluoreszenz-Resonanz-Energie-Transfer (10)
- GPCR (10)
- Mikrokerne (10)
- Adenosine receptors (9)
- G-Protein gekoppelte Rezeptoren (9)
- Angiotensin II (7)
- Biomarker (7)
- FRET (7)
- Genotoxizität (7)
- Herzinsuffizienz (7)
- heart failure (7)
- DNA (6)
- Genotoxicity (6)
- Gentoxizität (6)
- Maus (6)
- Mutagenität (6)
- Pharmakologie (6)
- cAMP (6)
- genomic damage (6)
- Adenosin (5)
- Aldosteron (5)
- Carcinogen (5)
- DNA binding (5)
- Dimerisierung (5)
- ERK1/2 (5)
- G-protein (5)
- Kleinkern (5)
- MAP-Kinase (5)
- Medizin (5)
- Micronuclei (5)
- Toxizität (5)
- biomarker (5)
- cardiac hypertrophy (5)
- nephrotoxicity (5)
- Adenylate cyclase (4)
- Calcium (4)
- Comet Assay (4)
- Cyclo-AMP (4)
- DNA-Schaden (4)
- G proteins (4)
- Genomschaden (4)
- Herzhypertrophie (4)
- Inhibition (4)
- Niere (4)
- apoptosis (4)
- bariatric surgery (4)
- calcium (4)
- comet assay (4)
- fluorescence resonance energy transfer (4)
- metabolism (4)
- micronucleus test (4)
- mutagenicity (4)
- mycotoxin (4)
- signal transduction (4)
- toxicity (4)
- 1 (3)
- Adrenerger Rezeptor (3)
- Beta-Rezeptor (3)
- Biotransformation (3)
- Carcinogenesis (3)
- Carcinogenicity (3)
- Carcinogens (3)
- Chronophin (3)
- Dialyse (3)
- Enzyme induction (3)
- Ernährung (3)
- G protein-coupled receptors (3)
- G-Protein (3)
- Hormone (3)
- Hypertonie (3)
- In vitro (3)
- Insulin (3)
- LC-MS (3)
- Leber (3)
- Magenchirurgie (3)
- Metabolismus (3)
- Mikrokern (3)
- Mikrokerntest (3)
- Muscarinrezeptor (3)
- NADPH-Oxidase (3)
- Nephrotoxizität (3)
- Nichtionisierende Strahlung (3)
- PDXP (3)
- Phosphatase (3)
- Phosphatasen (3)
- Phosphoglykolatphosphatase (3)
- Pneumolysin (3)
- Pyridoxalphosphat (3)
- RKIP (3)
- Rezeptor (3)
- Signaltransduktion (3)
- Zelle (3)
- cancer (3)
- carcinogenicity (3)
- cytoskeleton (3)
- differentiation (3)
- heart (3)
- hypertension (3)
- inflammation (3)
- liver (3)
- transcription factors (3)
- 18F-FDG (2)
- 5-Azacytidine (2)
- A1 adenosine receptors (2)
- Actin (2)
- Adenosine receptor (2)
- Adipositas (2)
- Aflatoxin (2)
- Alpha-2-Rezeptor (2)
- Ames test (2)
- Anthocyane (2)
- Apoptose (2)
- Apoptosis (2)
- Autoimmunerkrankung (2)
- BRET (2)
- Bakteriengift (2)
- Benfotiamin (2)
- Benzene (2)
- Bestrahlung (2)
- Beta-1-Rezeptor (2)
- Brustkrebs (2)
- Carcinogenese (2)
- Carcinogenität (2)
- DNA Binding (2)
- DNA Schaden (2)
- DNA repair (2)
- DNS-Schaden (2)
- DNS-Strangbruch (2)
- Diethylstilbestrol (2)
- Dose response (2)
- Dose-response relationship (2)
- Dosis-Wirkungs-Beziehung (2)
- Electropermeabilization (2)
- Elektrofusion (2)
- Elektroporation (2)
- Estrogen (2)
- FCS (2)
- Fluoreszenz (2)
- Furan (2)
- Förster Resonanz Energie Transfer (2)
- G protein coupled receptor (2)
- G-Protein gekoppelter Rezeptor (2)
- G-protein coupled receptor (2)
- Genetic instability (2)
- HPLC-MS (2)
- Heart failure (2)
- Herz (2)
- Hirnhautentzündung (2)
- Huh6 (2)
- Hypertrophie (2)
- Hämatopoetische Stammzellen (2)
- Hämodialyse (2)
- Inhalation (2)
- Kanzerogenese (2)
- Kardiomyopathie (2)
- Kongestive Herzmuskelkrankheit (2)
- Krebs (2)
- L5178Y cells (2)
- Lasiocarpin (2)
- Meningitis (2)
- Merkaptursäuren (2)
- Metabonomics (2)
- Micronucleus (2)
- Mikroskopie (2)
- Myokarditis (2)
- N-formyl peptides (2)
- Noradrenalin (2)
- PDE (2)
- PET (2)
- Paracetamol (2)
- Parathormon (2)
- Peptidtherapie (2)
- Pharmakokinetik (2)
- Pharmazie (2)
- Phosducin (2)
- Phosphodiesterase (2)
- Pyrrolizidinalkaloide (2)
- QIVIVE (2)
- Radioligand binding (2)
- Raf kinase inhibitor protein (2)
- Raf-Kinasen (2)
- Rat (2)
- Regulation (2)
- Reproductive toxicity (2)
- Risikoanalyse (2)
- Risk Assessment (2)
- Salmonella/microsome assay (2)
- Silicones (2)
- Sulforaphan (2)
- Terahertzbereich (2)
- Terahertzstrahlung (2)
- Toxicology (2)
- Toxin (2)
- Transgene Tiere (2)
- Zellkultur (2)
- Zellzyklus (2)
- actin (2)
- actinomycetes (2)
- adenosine (2)
- adenosine receptor (2)
- adenosine receptors (2)
- aldosterone (2)
- barbiturates (2)
- bariatrische Chirurgie (2)
- beta-adrenerge Signalwege (2)
- biased signaling (2)
- binding (2)
- biomedicine, general (2)
- cGMP (2)
- cancer risk (2)
- carcinogen (2)
- cell biology (2)
- cell culture (2)
- cisplatin (2)
- classification (2)
- comet-assay (2)
- cytokinins (2)
- dialysis (2)
- dialysis patients (2)
- environmental health (2)
- epigenetics (2)
- estrogen (2)
- familial DCM (2)
- fluorescence (2)
- furan (2)
- iPSC-cardiomyocytes (2)
- immunohistochemistry (2)
- in-vivo (2)
- insulin (2)
- kidney (2)
- kidneys (2)
- lymphocytes (2)
- mast cells (2)
- medicine (2)
- membrane skeleton (2)
- meningitis (2)
- mercapturic acid (2)
- mercapturic acids (2)
- metabonomics (2)
- myocarditis (2)
- non-ionizing radiation (2)
- obesity (2)
- occupational medicine/industrial medicine (2)
- oxidativer Stress (2)
- peripheral lymphocytes (2)
- pharmacogenetics (2)
- pharmacokinetics (2)
- pharmacology/toxicology (2)
- phosphorylation (2)
- pneumolysin (2)
- positron emission tomography (2)
- radiation (2)
- rat brain membranes (2)
- receptors (2)
- resveratrol (2)
- risk assessment (2)
- terahertz radiation (2)
- therapy (2)
- transgen (2)
- uremic toxins (2)
- vitamin B6 (2)
- yam (2)
- Östrogene (2)
- (Mouse L-cell) (1)
- (Rat brain membrane) (1)
- (Rat liver) (1)
- (Salmonella) (1)
- 1H-NMR-Spectroscopy (1)
- 2 (1)
- 2',7'-dichlorofluorescin (1)
- 2-Acetylaminofluorene (1)
- 2-Dichloroethane (1)
- 2-Dioxetane (1)
- 2-Generation reproduction (1)
- 2-acetylaminofluorene (1)
- 3 (1)
- 3-pentafluoropropene (1)
- 3-tetrafluoropropene (1)
- 3R (1)
- 4'-hydroxylation (1)
- 4-(p-nitrobenzyl)pyridine (1)
- 4-Aminobiphenyl (1)
- 4-aminobiphenyl (1)
- 4-dial (1)
- 6-benzylaminopurine (1)
- 7,8-Dihydroxyflavon (1)
- 7,8-dihydroxyflavone (1)
- 7,8-dihydroxyflavone (7,8-DHF) (1)
- 8-Hydroxy-deoxyguanosine (1)
- 8-Oxo-2’-desoxyguanosin (1)
- 8-oxo-2'-deoxyguanosine (1)
- A(2B) receptors (1)
- A1 (1)
- A1 Adenosine receptors (1)
- A2B adenosine receptor (1)
- A2BAR (1)
- A<sub>2</sub> Adenosine receptor (1)
- AAF (1)
- ADHS (1)
- AMPK (1)
- API-Massenspektrometrie (1)
- AUM (1)
- A\(_{2A}\) adenosine receptor antagonist (1)
- Acetaminophen (1)
- Acetylcysteinderivate (1)
- Acrylamid (1)
- Acrylamide (1)
- Actin cytoskeleton (1)
- Activation (1)
- Addition (1)
- Adenosine (1)
- Adenosine receptor antagonists (1)
- Adenylatcyclaseassay (1)
- Adipositaschirurgie (1)
- Adrenalin (1)
- Adrenerger Neuronenblocker (1)
- Adrenergic Receptor (1)
- Adrenergic neurone blocking agent (1)
- Adrenergic receptor (1)
- Adrenergisches System (1)
- Adrenozeptor (1)
- Advanced glycosylation end products (1)
- Adverse Outcome Pathway (1)
- Adverse outcome pathway (AOP) (1)
- Aflatoxin B1 (1)
- Aktionspotenzial (1)
- Aktivierung (1)
- Aldosteronantagonist (1)
- Alkylantien (1)
- Alkylation (1)
- Allosterie (1)
- Alternans (1)
- Alterung (1)
- Alzheimers disease (1)
- Amino acid composition (1)
- Amino acids (1)
- Aminosäuren (1)
- Anabolieagent (1)
- Aneugene (1)
- Angewandte Toxikologie (1)
- Angiotensin (1)
- Angiotensin II Typ 1a-Rezeptor (1)
- Angiotensin-II-Blocker (1)
- Angst (1)
- Aniline derivatives (1)
- Animal model (1)
- Anthraquinone glycosides (1)
- Antibodies (1)
- Antikörper (1)
- Antimutagen (1)
- Antioxidans (1)
- Anxiety (1)
- Arsen (1)
- Aryl hydrocarbon rnonooxygenase (1)
- Arzneimittel (1)
- Astrozyt (1)
- Atherosclerosis (1)
- Atherosklerose (1)
- Atria (1)
- Aufmerksamkeits-Defizit-Syndrom (1)
- Autofocus (1)
- Azole (1)
- Azoles (1)
- B cells (1)
- BETA(2)-adrenergic receptor (1)
- BG-1 Zellen (1)
- BG-1 cells (1)
- BMS-5 (1)
- Background DNA damage (1)
- Bacterial Toxins (1)
- Bacterial meningitis (1)
- Bakterielle Hirnhautentzündung (1)
- Bakterien (1)
- Barbiturat (1)
- Barbiturates (1)
- Barth syndrome (1)
- Bcl-2 (1)
- Benzefuran dioxetane (1)
- Benzefuran epoxide (1)
- Benzo(a)pyrene-DNA binding (1)
- Berenil (1)
- Beta(1)-adrenergic receptor (1)
- Beta(2)-adrenergic receptor (1)
- Beta- adrenergic receptors (1)
- Beta-1-receptor (1)
- Beta-Adrenergic Receptor (1)
- Beta-Adrenozeptor (1)
- Beta-Receptor subtypes (1)
- Beta-Rezeptor Subtypen (1)
- Beta-adrenerge Rezeptoren (1)
- Bilirubin (1)
- Bindungsassay (1)
- Bioluminescence resonance energy transfer (1)
- Biomarkers (1)
- Biosensor (1)
- Biostatistik (1)
- Bisphenol A (1)
- Blutbildendes System (1)
- Blutgefäß (1)
- Blutstammzelle (1)
- Bombyx mori (1)
- BrdU (1)
- Bromodeoxyuridine labeling (1)
- C1q/TNF related protein (CTRP) (1)
- C1q/tumor necrosis factor-related proteins (1)
- CAMP production (1)
- CCT (1)
- CFC replacements (1)
- CFP (1)
- CHO-Zellen (1)
- CHO-cells (1)
- CIB1 (1)
- CMF-Therapie (1)
- CRISPR Cas9 (1)
- CRISPR/Cas9 (1)
- CTRP (1)
- CXCR4 (1)
- CYP19 (1)
- CYP51 (1)
- CaMKII (1)
- Calcium-bindende Proteine (1)
- Calciumkanal (1)
- Cancer prevention (1)
- Carcinogen risk Individual susceptibili (1)
- Carcinogenic potency (1)
- Cardiac myocyte ; Beta-Receptor ; Muscarinic receptor ; cAMP ; G-protein ; Serum (1)
- Cardiomyocyte (1)
- Caseinkinase 2 (1)
- Caspase-1 (1)
- Caveolae (1)
- Celecoxib (1)
- Cell adhesion (1)
- Cell death and comet assay (1)
- Cell transformation (1)
- Chemical carcinogenesis (1)
- Chemokine (1)
- Chemokine receptors (1)
- Chemometrie (1)
- Chemotactic receptors (1)
- Chemotherapie (1)
- Chlorfluorkohlenstoffe (1)
- Choline deficiency (1)
- Cholinesteraseinhibitor (1)
- Chromosome aberration (1)
- Chromosome distribution (1)
- Chronic heart-failure (1)
- Chronical renal failure (1)
- Clonidin (1)
- Coffein (1)
- Cofilin (1)
- Colon cancer (1)
- Comet assay (1)
- Comet-Assay (1)
- Covalent DNA binding (1)
- Covalent binding (1)
- Covalent binding index (1)
- Covalent binding index - Diethylstilbestrol (1)
- Cyclic AMP (1)
- Cyclo-GMP (1)
- Cytochalasin-B micronucleus assay (1)
- Cytochrom P450 (1)
- Cytochrome b5 (1)
- Cytokine (1)
- Cytologie (1)
- DAMGO (1)
- DCM (1)
- DCM genetic background (1)
- DES (1)
- DIPP2a (1)
- DIPP2a-Protein (1)
- DNA Damage (1)
- DNA adduct . Repair endonuclease (1)
- DNA adducts (1)
- DNA base excision repair (1)
- DNA binching (1)
- DNA damage response (1)
- DNA metabolism (1)
- DNA methylation (1)
- DNA transfection (1)
- DNA-Addukte (1)
- DNA-Binding (1)
- DNA-Damage (1)
- DNA-Reparatur (1)
- DNA-Schäden (1)
- DNA-damage (1)
- DNS (1)
- DNS-Bindung (1)
- DNS-Doppelstrangbruch (1)
- DNS-Reparatur (1)
- Datenanalyse (1)
- Depression (1)
- Dermatologie (1)
- Di (1)
- Dialysepatienten (1)
- Dialysis (1)
- Diclofenac (1)
- Dietary process-related contaminants (1)
- Differenzierung (1)
- Differenzierungszustand (1)
- Diisononyl phthalate (1)
- Dilatative Kardiomyopathie (1)
- Dilated cardiomyopathy (1)
- Dioscorea (1)
- Diskriminanzanalyse (1)
- Dopamin-beta-Hydroxylase Promotor (1)
- Dose response relationships (1)
- Drug resistance (1)
- Dualstere Liganden (1)
- Dualsteric Ligands (1)
- EAD (1)
- EGF-Rezeptor (1)
- EGF-receptor (1)
- ERK Dimerisierungsdefizienz (1)
- ERK signaling (1)
- ERK-Kaskade (1)
- ERK-Monomer (1)
- ERK-cascade (1)
- ERK1/2 Dimerisierung (1)
- ERK1/2-Autophosphorylierung (1)
- ERK2d4 (1)
- ESDR (1)
- Ecdyson (1)
- Effekt-Modifizierung (1)
- Eierstockkrebs (1)
- Einwärtsgleichrichtung (1)
- Einzelzellgelelektrophorese (1)
- Electric Field (1)
- Electrical breakdown (1)
- Electrophiles (1)
- Elektrokardiogramm (1)
- Elektromagnetische Felder (1)
- Embryonalen Stammzellen (1)
- Embryonalentwicklung (1)
- Emodin (1)
- Empfindlichkeit (1)
- Endogenous genotoxicity (1)
- Endokrinologie (1)
- Endothelzelle (1)
- Endozytose (1)
- Entzündung (1)
- Epac (1)
- Epigenetik (1)
- Epoxide hydrolase (1)
- Erk1/2 (1)
- Ersatzstoff (1)
- Erythrozyt (1)
- Estrone (1)
- Ethionine (1)
- Eukaryotic cell (1)
- Excitotoxicity (1)
- Expositionsmarker (1)
- External exposure assessment (1)
- Extrakorporale Dialyse (1)
- FACS (1)
- FCKW-Ersatzstoffe (1)
- FHK (1)
- FPG protein (1)
- FRAP (1)
- FRET sensors (1)
- Fabry Disease (FD) (1)
- Fettsucht (1)
- Fibromyalgie (1)
- Fibrose (1)
- Fischer 344 rats (1)
- Fl (1)
- FlAsH (1)
- Flow cytometry (1)
- Flugzeitmassenspektrometrie (1)
- Fluorescence (1)
- Fluorescence Correlation Spectroscopy (1)
- Fluorescence Microscopy (1)
- Fluorescence resonance energy transfer (1)
- Fluorescence-resonance-energy-transfer (1)
- Fluoreszenz <Motiv> (1)
- Fluoreszenzkorrelationsspektroskopie (1)
- Fluoreszenzmikroskopie (1)
- Fluorkohlenwasserstoffe (1)
- Fluoxetin (1)
- Fluoxetine (1)
- Folsäure (1)
- Frank-Starling-Gesetz (1)
- Friedreich’s ataxia (1)
- Fumonisin B1 (1)
- Fumonisine (1)
- Functional analyses (1)
- Fungizid (1)
- Förster Resonance Energy Transfer (1)
- G Protein (1)
- G Protein-Coupled Receptor (1)
- G beta gamma (1)
- G protein coupled receptor (GPCR) (1)
- G protein-coupled receptor (1)
- G protein-coupled receptor kinase (1)
- G protein-coupled receptor kinase 2 (GRK2) (1)
- G protein-gekoppelte Rezeptor Kinase 2 (GRK2) (1)
- G-Protein-gekoppelter-Rezeptor (1)
- G-Proteine (1)
- G-protein-coupled receptors (1)
- GABA-receptor complex (1)
- GC-MS (1)
- GC/MS (1)
- GIRK (1)
- GPCR dimerisation (1)
- GPCR signaling (1)
- GPCRs (1)
- GTP-bindende Proteine (1)
- Gastric carcinogenesis (1)
- Gb3 and lyso-Gb3 biomarkers (1)
- Gbetagamma-Untereinheiten (1)
- Gbetagamma-subunits (1)
- Gebärmutterhalskrebs (1)
- Gefäßentwicklung (1)
- Gegensatz (1)
- Genanalyse (1)
- Gene Transfer (1)
- Gene transfer (1)
- Genmutation (1)
- Genomische Instabilität (1)
- Genotoxicitiy (1)
- Genotyp (1)
- Genregulation (1)
- Gentoxikologie (1)
- Gi/o (1)
- Gilbert Syndrom (1)
- Gilbert´s Syndrome (1)
- Glatte Muskulatur (1)
- Glioblastom (1)
- Glucuronidation (1)
- Glukuronidierung (1)
- Glutathion S-Konjugat (1)
- Glutathione Stransferase (1)
- Glycerin-3-phosphat (1)
- Glycerinphosphate (1)
- Gq-Protein (1)
- Grün fluoreszierendes Protein (1)
- Guanin Nukleotid Austauschfaktor (1)
- Guaninnucleotid-Austauschfaktoren (1)
- Guanylatcyclase (1)
- HAD-Phosphatasen (1)
- HCM (1)
- HCN channel (1)
- HCN-Kanal (1)
- HFC245fa (1)
- HIPEC therapy (1)
- HIV (1)
- HIV infection (1)
- HPLC-MS/MS method (1)
- Hals-Nasen-Ohren-Tumor (1)
- Harn (1)
- Hauptkomponentenanalyse (1)
- HeLa cells (1)
- Hemmung der Proliferation schnell wachsender Krebszellen (1)
- Herpesviren (1)
- Herzfrequenz (1)
- Herzmuskelzelle (1)
- Herzrhythmusstörung (1)
- Hietzeschockprotein (1)
- High-thropughput screening (1)
- High-throughput screening (1)
- Hintergrund-DNA-Schaden (1)
- Hochdurchsatz-Screening (1)
- Hoechst 33258 dye (1)
- Homocystein (1)
- Hsp90 (1)
- Human (1)
- Human platelets (1)
- Humane Hämatopoetische Stammzellen (1)
- Hybridoma (1)
- Hydroxylradikal (1)
- Hyperinsulinämie (1)
- Hypernephrom (1)
- Hypertension (1)
- Hyperthermie (1)
- Hypertrophische Herzmuskelkrankheit (1)
- Häm (1)
- Hämatopoese (1)
- Hämodiafiltration (1)
- Hämoglobinaddukte (1)
- I1 Imidazolin Bindungsstelle (1)
- I1 imidazoline binding site (1)
- Immunization (1)
- Immunkardiomyopathie (1)
- Immunoblot (1)
- Immunologie (1)
- In vitro testing (1)
- In vitro toxicity testing (1)
- In vivo (1)
- In-silico Modell (1)
- Inflammation (1)
- Inhibitor (1)
- Interferenz (1)
- Inward Rectification (1)
- Ischemia/reperfusion (1)
- Janus-Aktivität (1)
- K + -channels (1)
- Kaffee (1)
- Kalzium (1)
- Kandidatengene (1)
- Kaninchen (1)
- Kardiomoyzyten (1)
- Kardiomyozyt (1)
- Kardiomyozyten (1)
- Karzinogenese (1)
- Katecholamine (1)
- Kidneys (1)
- Kinase signaling (1)
- Kinder (1)
- Kinetochore (1)
- Kinetochores (1)
- Klassifizierung (1)
- Klastogene (1)
- Knockout (1)
- Kognitive Beeinträchtigung (1)
- Kombination (1)
- Konformationsänderung (1)
- Kopf-Hals-Tumor (1)
- Krebs <Medizin> (1)
- L5178Y-Zellen (1)
- LC-MS/MS (1)
- LIMK (1)
- LPS (1)
- LTB4 receptor (1)
- Latrophilin (1)
- Lebendzellmikroskopie (1)
- Leukocyte/endothelium interaction (1)
- Ligand <Biochemie> (1)
- Liganden (1)
- Lipidom (1)
- Lipidomics (1)
- Liver (1)
- Lung (1)
- Lymphozyt (1)
- Lymphozyten (1)
- Lysosom (1)
- MAO-Hemmer (1)
- MAP (1)
- MAP-kinase (1)
- MDA-MB-231 breast cancer cells (1)
- MDA-MB-231-Brustkrebszellen (1)
- MIBG (1)
- MMQ cells (1)
- MMR-Reparatur (1)
- Magenkrebs (1)
- MammaJian mutagenicity test (1)
- Mammakarzinom (1)
- Map-kinase (1)
- Massenspektrometrie (1)
- Mastzelle (1)
- Matrix-Metalloprotease (1)
- Matrix-Metalloproteinase (1)
- Mauslymphomtest (1)
- Mauslymphomzellen (1)
- Mauslymphomzellen L5178Y (1)
- Mechanism of action (1)
- Melanocortin 4 receptor (MC4R) (1)
- Melanocyte stimulating hormones MSH (1)
- Melanoma (1)
- Melanomzelllinien (1)
- Membranrezeptor (1)
- Merkaptolaktat (1)
- Merkaptursäure (1)
- Metabolic activation (1)
- Metabolism (1)
- Metabolism saturation (1)
- Metabolite von Morphin (1)
- Metabolites of morphine (1)
- Metabolom (1)
- Metabolomics (1)
- Metabonomix (1)
- Methode der partiellen kleinsten Quadrate (1)
- Methylierung (1)
- Methylphenidat (1)
- Methymethansulfonat (1)
- Microcirculation (1)
- Micronucleus formation (1)
- Micronucleus test (1)
- Microscopy (1)
- Mikrokernfrequenz (1)
- Mikrokernfrequenzanalyse (1)
- Mikronukleus-Assay (1)
- Mineralokortikoidrezeptor (1)
- Mitosis (1)
- Mobiles Endgerät (1)
- Mobilfunk (1)
- Mobilfunkstrahlung (1)
- Molekularpharmakologie (1)
- Monoaminoxidase (1)
- Morphin (1)
- Multivariate Analyse (1)
- Mundschleimhaut (1)
- Mundschleimhautzellen (1)
- Mutagen (1)
- Mutagenicity (1)
- Mutagenicity assay (1)
- Mutagenitätstest (1)
- Mutagens (1)
- Mutation (1)
- Mutation assay (1)
- Mykotoxin (1)
- Myocard (1)
- Myofilament (1)
- Myosin (1)
- N-methyl-N-nitrosourea (1)
- N1E 115 cells (1)
- NADPH oxidase (1)
- NHERF (1)
- NOF (1)
- Na/H-Austauscher (1)
- Na/H-exchanger (1)
- Na\(_V\)1.8 (1)
- Natrium-Calcium-Austauscher (1)
- Nebenniere (1)
- Neomycin Resistance (1)
- Nephrotoxicity (1)
- Nervennetz (1)
- Nervenzelle (1)
- Neuronale (1)
- Niereninsuffizienz (1)
- Nierenschädigung (1)
- Nierenschädigungsmarker (1)
- Nierenzellkarzinom (1)
- Nitrosation (1)
- Nitrosativer Stress (1)
- Nitrosierung (1)
- No:cGMP-Signalling (1)
- No:cGMP-Signalweg (1)
- Nrf 2 (1)
- OXPHOS (1)
- Opiatrezeptor (1)
- Ortspezifische Mutagenese (1)
- Oxidative Stress (1)
- Oxidative stress (1)
- Oxygen radical (1)
- PBPK/PBTK model (1)
- PDE-Hemmung (1)
- PDE2 (1)
- PDXP inhibitors (1)
- PKA (1)
- PLCβ3 (1)
- PLP (1)
- PMCA (1)
- PTH1R (1)
- Paclitaxel (1)
- Partial Agonists (1)
- Partialagonismus (1)
- Passivrauchen (1)
- Patulin (1)
- Peptides (1)
- Perforine (1)
- PhD thesis pharmacology (1)
- Pharmakogenetik (1)
- Phenobarbital (1)
- Phosducin-like Proteine (1)
- Phosducin-ähnliches protein (PhLP) (1)
- Phosphodiesterasen (1)
- Phosphoglykolat (1)
- Phosphoglykolat-Phosphatase (1)
- Phospholipase C (1)
- Phosphorylierung (1)
- Photoaffinity labelling (1)
- Physiologically based kinetic models (1)
- Physiologie (1)
- Phytohormone (1)
- Phänotyp (1)
- Phäochromozytomzellen (1)
- Plasmamembran-Kalzium-ATPase (1)
- Plazenta (1)
- Pointmutation (1)
- Pore (1)
- Pore formation (1)
- Pore-formation (1)
- Porenbildung (1)
- Prevalence (1)
- Prognostic impact (1)
- Prolactin (1)
- Propenderivate (1)
- Proteasom (1)
- Protein (1)
- Protein Folding (1)
- Protein Interaction (1)
- Protein binding (1)
- Protein coding (1)
- Protein-Protein-Wechselwirkung (1)
- Proteinaddukte (1)
- Proteinbindung (1)
- Proteinfaltung (1)
- Proteinkinase A (1)
- Proteinkinase C (1)
- Proteinkinase CK2 (1)
- Proteintyrosinphosphatase (1)
- Proteolyse (1)
- Protonen-NMR-Spektroskopie (1)
- Pyridoxal phosphate phosphatase (1)
- Pyridoxalphosphat Phosphatase (1)
- Quantitative risk assessment (1)
- RAMP (1)
- RBM20 mutations (1)
- RGS2 (1)
- RNA degradation (1)
- RNS-Interferenz (1)
- ROS (1)
- Radiation inactivation (1)
- Radicals (1)
- Radioligand binding - 86Rb + -efflux (1)
- Radioligands (1)
- Radioligauds (1)
- Radiosensibilisierung (1)
- Raf Kinase Inhibitor Protein (RKIP) (1)
- Raf1 (1)
- Raman micro-spectroscopy (1)
- Rat Iiver microsomes (1)
- Rat liver peroxisome (1)
- Ratte (1)
- Raucher (1)
- ReAsH (1)
- Reactive intermediates (1)
- Reaktive Sauerstoffspezies (1)
- Reaktive Zwischenstufe (1)
- Real-Time quantitative PCR (1)
- Receptor (1)
- Receptor dynamics (1)
- Refraktärzeit (1)
- Regulator of G protein signaling 2 (1)
- Renin-Angiotensin-Aldosteron-System (1)
- Renin-Angiotensin-System (1)
- Resistenzentwicklung (1)
- Resveratrol (1)
- Retinales S-Antigen (1)
- Rgs2 (1)
- Rho-GTPasen (1)
- Rho-Proteine (1)
- Riddelliin (1)
- Riot control agents (1)
- Risikobewertung (1)
- Risk assessment (1)
- Risk estimation (1)
- Risk-factors (1)
- SCN5a (1)
- ST-elevation myocardial infarction (1)
- SUMO (1)
- Salmonella typhimurium (1)
- Schwesterchromatidenaustausche (1)
- Sekunde (1)
- Selenmangel (1)
- Senecionin (1)
- Seneciphyllin (1)
- Sensitivity (1)
- Sensor (1)
- Short-term Carcinogenicity Test (1)
- Short-term tests (1)
- Signal transduction (1)
- Signalkette (1)
- Small RNA (1)
- Species Differences (1)
- Species differences (1)
- Spermatogenesis (1)
- Speziesunterschiede (1)
- Spironolacton (1)
- Spontaneous tumours (1)
- Src (1)
- Stable Transformation (1)
- Statin (1)
- Stickstoffmonoxid (1)
- Stickstoffoxidsynthase (1)
- Stoffwechsel (1)
- Strahlentherapie (1)
- Streptococcus pneumoniae (1)
- Streptomyces (1)
- Stress (1)
- Structureactivity relationship (1)
- Styrol (1)
- Substratspezifitätsschleife (1)
- Sudden Cardiac Death (1)
- Sulfonylharnstoffe (1)
- Sulforaphane (1)
- Sympathikus (1)
- Synergie (1)
- Synergismus (1)
- Systembiologie (1)
- Säugerzellen (1)
- Säugetiere (1)
- T cells (1)
- TCP-1 alpha (1)
- TIRF (1)
- TK6 cells (1)
- Tabakrauch (1)
- Target size (1)
- Tetrachlormethan (1)
- Tetracystein-Motive (1)
- Tetracystein-Motivee (1)
- Thebain (1)
- Theophylline (1)
- Thrombin (1)
- Thymidine glycol (1)
- Tiermodell (1)
- Time-of-flight (1)
- Toluene (1)
- Toxicokinetics (1)
- Toxikokinetik (1)
- Toxizitätstest (1)
- Transfection (1)
- Transgene Mäuse (1)
- Transgenes Mausmodell (1)
- Transgenic mice (1)
- Transgenic mouse (1)
- Transgenie mice (1)
- Transkription (1)
- Transkriptionsfaktoren (1)
- Trenbolone (1)
- Trifluorpropionsäure (1)
- Tritiated Water (1)
- Troponin (1)
- Tumorpromotion (1)
- Tumorzelle (1)
- Tumorzellproliferation (1)
- Tyrosin (1)
- Tyrosin phosphatase (1)
- UCP2 (1)
- UCP2-Protein (1)
- UGT1A1 (1)
- Ubiquitin (1)
- Unscheduled DNA synthesis (1)
- Urämische Toxine (1)
- Uterine tumors (1)
- VASP (1)
- Validierung (1)
- Valvular heart-desease (1)
- Venerologie (1)
- Vitamin B12 (1)
- Vitamin B6 (1)
- Vitamin B6 Metabolismus (1)
- Vitamin E Mangel (1)
- Vitamin-B6-Stoffwechsel (1)
- Volume distribution (1)
- WD 40 Repeat Proteins (1)
- Wachstum (1)
- Wachstumskonus (1)
- Water resources (1)
- Wirkstoff-Rezeptor-Bindung (1)
- Xanthines (1)
- YFP (1)
- Zell-Adhäsion (1)
- Zelladhäsion (1)
- Zelldifferenzierung (1)
- Zelllinie (1)
- Zellproliferationssteigerung (1)
- Zellskelett (1)
- Zellteilung (1)
- Zelltransport (1)
- Zellzykluskontrolle (1)
- Zigarettenrauch (1)
- Zyklopeptid (1)
- [3H]PIA binding (1)
- absorption (1)
- activation (1)
- active zone (1)
- acute slices (1)
- adduct (1)
- adenine (1)
- adenosine 3',5'-cyclic monophosphate (1)
- adenylate cyclase (1)
- adenylyl cyclase signaling cascade (1)
- adenylyl-cyclase isoforms (1)
- adhesion GPCR (1)
- adiponectin (1)
- adipose tissue (1)
- adrenal gland (1)
- adrenerg (1)
- adrenerge Rezeptoren (1)
- adrenergic (1)
- adrenergic receptors (1)
- adrenoceptor (1)
- adult ADHD (1)
- adult cardiac myocytes (1)
- advanced glycosylation end product (1)
- adverse outcome pathway (1)
- adverse outcome pathway (AOP) (1)
- aflatoxin (1)
- aflatoxin B1 (1)
- ageing (1)
- agonists (1)
- alkylating agent (1)
- alkylating agents (1)
- alkylation (1)
- allelic variant (1)
- allosteric modulation (1)
- alpha2 (1)
- alpha2-KO Maus (1)
- alpha2-KO mouse (1)
- alpha2-Rezeptor (1)
- alpha2-adrenerge Rezeptoren (1)
- alpha2-adrenergic receptors (1)
- alpha2-receptor (1)
- alternative methods (1)
- amine (1)
- amino acid (1)
- aneugens (1)
- angiotensin II (1)
- angiotensin II type 1a receptor (1)
- antagonists (1)
- anthocyanins (1)
- anti-Parkinson agents (1)
- anti-inflammatory agents (1)
- antibacterial/antiviral drug (1)
- antibodies (1)
- antibody/autoantibody (1)
- antimutagenicity (1)
- antioxidants (1)
- aortocaval fistula model (1)
- aromatic amides (1)
- arrhythmia (1)
- arrhythmogenesis (1)
- arsenite (1)
- assay (1)
- association (1)
- astrocytes (1)
- atopic eczema (1)
- atopische Erkrankungen (1)
- atrial natriuretic peptide (1)
- autophosphorylation of ERK1/2 (1)
- avaliação de risco (1)
- bacterial meningitis (1)
- base excision repair (incision activity) (1)
- benfotiamine (1)
- beta-adrenerge Rezeptoren (1)
- beta-adrenergic signal transduction (1)
- beta2-adrenoceptor knockout (1)
- beta3 CL 316,243 (1)
- binding affinity (1)
- bioactive compounds (1)
- biofilms (1)
- biological techniques (1)
- biology (1)
- biomarker of exposure (1)
- biomarkers (1)
- biosensor (1)
- biotransformation (1)
- bisphenol a (1)
- blood coagulation factor XIII (1)
- blood plasma (1)
- blood pressure (1)
- blood samples (1)
- bombyx mori (1)
- bone marrow (1)
- brain damage (1)
- brain membranes (1)
- buccal mucosa (1)
- caffeine (1)
- calcitonin gene-related peptide (1)
- calcium channel (1)
- calmodulin (1)
- carcinogenesis (1)
- cardiac magnetic resonance imaging (1)
- cardiac myocyte ; muscarinic K current ; G-protein ; Albumin ; serum (1)
- cardiac remodelling (1)
- cardiomyocyt (1)
- cardiomyocyte (1)
- cardiomyocytes (1)
- cardiomyopathy (1)
- cardiovascular diseases (1)
- casein kinase 2 (1)
- catecholamines (1)
- caveolae (1)
- caveolin-1 (1)
- cell adhesion (1)
- cell fate (1)
- cell fusion (1)
- cell proliferation (1)
- cell signalling (1)
- cell staining (1)
- cell-cycle (1)
- cellular-trafficking (1)
- chalcone (1)
- checkpoints (1)
- chemotactic receptors (1)
- chemotaxis (1)
- child health (1)
- children (1)
- cholesterol depletion (1)
- cholesterol-dependent cytolysin (1)
- cholinesterase (1)
- cholinesterase inhibitors (1)
- chromaffin granulas (1)
- chromaffine Granulas (1)
- chromosomal damage (1)
- chronic heart failure (1)
- chronic kidney disease (1)
- chronical stress (1)
- chronischer Stress (1)
- chronophin (1)
- cis-2-Buten-1 (1)
- classification and labeling (1)
- clastogens (1)
- clinical genetics (1)
- clonidine (1)
- co-culture (1)
- coated vesicles (1)
- coffee (1)
- cognitive impairment (1)
- coherent anti-Stokes Raman scattering (CARS) microscopy (1)
- comet assay analysis (1)
- compartments (1)
- computational biophysics (1)
- conduction disease (1)
- conformational auto-epitope (1)
- conjugated mycotoxins (1)
- constitutive activity (1)
- contact lens (1)
- continuous (1)
- contractility (1)
- control of the cell cycle (1)
- coumarin (1)
- coupled (1)
- coupled receptor (1)
- covalent (1)
- covalent binding (1)
- creatinine (1)
- crystal structure (1)
- cyclic AMP (1)
- cyclic dipeptide (1)
- cyclic nucleotides such as cyclic adenosine monophosphate (1)
- cyclic peptides/cyclopeptides (1)
- cyclic-AMP (1)
- cyclic-gmp (1)
- cyclo-AMP (1)
- cyclopeptide therapy (1)
- cytochrome P450 2C9 (1)
- cytochrome P450s (1)
- cytochrome p450 (1)
- cytogenetic effects (1)
- cytokinesis-block micronucleus assay (1)
- cytome biomarkers (1)
- cytosol (1)
- cytotoxic (1)
- dCIRL (1)
- danio rerio (1)
- definition (1)
- dendritic spines (1)
- desensitization (1)
- detrusor muscle (1)
- developmental biology (1)
- diabetes (1)
- diagnosis (1)
- dicyclohexyl phthalate (1)
- diet (1)
- differentiation status (1)
- dilated cardiomyopathy with ataxia (1)
- disrupting chemicals (1)
- disruptor endócrino (1)
- dna damage (1)
- dna strand break (1)
- docking (1)
- domains (1)
- dopamine-beta-hydroxylase-promotor (1)
- dormancy (1)
- dose (1)
- dose response (1)
- down-regulation (1)
- drug (1)
- dualsteric ligands (1)
- dunce (1)
- eccentric hypertrophy (1)
- ecdysone (1)
- ectodomain cleavage (1)
- efficient intervention points (1)
- embryonic stem cell (1)
- end-stage renal disease (1)
- endocrine disruptor (1)
- endogenous (1)
- endothelial cells (1)
- energy-transfer (1)
- environm. tobacco smoke (1)
- environmental phenols (1)
- enzyme-linked immunoassays (1)
- estrogen receptor (1)
- estrogens (1)
- ethanol (1)
- etoposide (1)
- etox database (1)
- eugenol (1)
- exposição humana (1)
- exposure (1)
- extrapolation (1)
- fatty liver (1)
- fentanyl (1)
- fetal testis (1)
- fibrosis (1)
- fluorescence correlation spectroscopy (1)
- fluorescence detection (1)
- fluorescence imaging (1)
- fluorescence recovery after photobleaching (1)
- fluorescent probes (1)
- fluorocarbons (1)
- folic acid (1)
- food contact materials (1)
- food safety (1)
- food security (1)
- formyl peptides (1)
- fumonisin B1 (1)
- functional clustering (1)
- fungi (1)
- gastrointestinal cancer (1)
- general medicine (1)
- genetics (1)
- genetischer Schadens (1)
- genomprotektiv (1)
- genotoxic (1)
- genotoxic agents (1)
- genotoxisch (1)
- genotoxische Agenzien (1)
- genotypes (1)
- genotyping (1)
- glucuronide (1)
- glutamate (1)
- glutathion S-conjugate (1)
- glycolytic flux control (1)
- gprotein (1)
- gravidez (1)
- growth (1)
- growth cone (1)
- guanine nucleotide exchange factor (1)
- hA<sub>3</sub>AR (1)
- hOCT1 (1)
- haematopoietic stem cells (1)
- halo olefines (1)
- haloacid dehalogenase (1)
- head and neck cancer (1)
- healing and remodelling processes (1)
- heart rate (1)
- heat shock protein (1)
- heme (1)
- hemodiafiltration (1)
- hemodialysis (1)
- hemodialysis patients (1)
- hemoglobin adducts (1)
- heterogeneous population (1)
- hiPSC-CM (1)
- hidden mycotoxins (1)
- histamine release (1)
- homeostasis (1)
- homocysteine (1)
- homodimerization (1)
- hormone receptors (1)
- huh6 (1)
- human (1)
- human A(3) (1)
- human biomonitoring (1)
- human exposure (1)
- human hematopoietic stem cells (1)
- human lung (1)
- hydrofluorocarbons (1)
- hypertonic solution (1)
- hypertrophy (1)
- identification (1)
- idiosyncratic drug toxicity (1)
- idiosynkratische Arzneistofftoxizität (1)
- impact pharmacogenetics (1)
- in vitro (1)
- in vivo (1)
- in-silico model (1)
- individual (1)
- indolylpyrimidylpiperazines (1)
- induced pluripotent stem cell cardiomyocytes (1)
- induced pluripotent stem cells (1)
- inducible transgene (1)
- induzierbares Transgen (1)
- induzierte Mutation (1)
- induzierte Phosphatasen MKP-1 und MKP-2 (1)
- inflammatory diseases (1)
- inhalation (1)
- inhibitor (1)
- inhibitors (1)
- insulin signaling (1)
- internalization (1)
- international union (1)
- intracellular calcium release (1)
- intracellular loop (1)
- intrinsic metabolism (1)
- ionic look (1)
- irradiation (1)
- ischemic stroke (1)
- isoproterenol (1)
- kardiale Hypertrophie (1)
- key event relationship (1)
- kinases (1)
- laminopathy (1)
- lamivudine (1)
- lasiocarpine (1)
- late Na\(^+\) current (I\(_{NaL}\)) (1)
- legislation (1)
- life (1)
- ligand binding (1)
- ligandenselektive Konformationen (1)
- lignaselective conformations (1)
- lipid rafts (1)
- lipidomics (1)
- listeriolysin O (1)
- live imaging (1)
- liver microsomes (1)
- living vells (1)
- long-read sequencing (1)
- lovastatin (1)
- lysosomal disruption (1)
- lysosomal storage disorders (1)
- lysosomaler Overload (1)
- lösliche Guanylylcyclase (1)
- mTOR-inhibitor RAD-001 (1)
- maintenance of genomic integrity (1)
- male rats (1)
- mammalian cells (1)
- mammalian genomics (1)
- mao-inhibiters (1)
- marine sponges (1)
- markers of exposure (1)
- masked mycotoxins (1)
- mass spectrometry (1)
- matrix metalloproteinase (1)
- maturation strategies (1)
- mechanotransduction (1)
- membrane (1)
- membrane transporters (1)
- memory B cells (1)
- mercaptolactic acid (1)
- meta-Iodbenzylguanidin (1)
- meta-iodobenzylguanidine (1)
- metabolites (1)
- metabolomics (1)
- metabotropic signalling (1)
- methyl methanesulfonate (1)
- methylation (1)
- miR-21 (1)
- microRNA-21 (1)
- micronucleus (1)
- micronucleus assay (1)
- micronucleus frequency (1)
- micronucleus- assay (1)
- microvessel permeability (1)
- mild (1)
- mismatch repair (1)
- mitochondria (1)
- mitochondrial DNA polymerase γ (1)
- mitochondrial cardiomyopathy (1)
- mitotic catastrophe (1)
- mitotic disturbance (1)
- mixture models (1)
- mobil phone radiation (1)
- modelo PBPK/PBTK (1)
- modified mycotoxins (1)
- molecular biology (1)
- molecular dynamics (1)
- molecular modeling (1)
- molecular modelling (1)
- monoamine oxidase (1)
- monogenetic cardiomyopathies (1)
- mortality (1)
- mouse (1)
- mouse lymphoma L5178Y (1)
- mouse lymphoma cells (1)
- mouse models DNA damage (1)
- mucosa (1)
- multivariate analysis (1)
- multivariate data analysis (1)
- muscarinic acetylcholine receptor (1)
- muscarinic aceylcholine receptor (1)
- mutagen (1)
- mutant mice (1)
- mutation triggers (1)
- mycotoxin derivates (1)
- mycotoxin metabolites (1)
- mycotoxins (1)
- myocardium (1)
- myosin (1)
- n-hexyl phthalate (1)
- nanopore (1)
- natural (1)
- neocortex (1)
- neurodegenerative diseases (1)
- neuronal (1)
- neuronal dendrites (1)
- neurons (1)
- neutrophils (1)
- nicht additive Effekte (1)
- nitric oxide (1)
- nitric-oxide (1)
- nitrosation (1)
- nitrosative stress (1)
- nitroso compound (1)
- no (1)
- non-additive effects (1)
- noradrenaline (1)
- nutritional composition (1)
- o-Chlorobenzylidene malononitrile (1)
- occurrence (1)
- ochratoxin A (1)
- octopamine (1)
- oligomerization (1)
- opioid ligands (1)
- opioid receptor (1)
- optimal drug combination (1)
- optimal drug targeting (1)
- optimal pharmacological modulation (1)
- optimal treatment strategies (1)
- organ toxicity (1)
- ovarian cancer (1)
- oxidative Stressmarker (1)
- oxidative stress marker (1)
- p53 (1)
- paclitaxel (1)
- parathyroid hormone (1)
- parathyroid hormone 1 receptor (1)
- partial agonists (1)
- passive smoking (1)
- performance liquid-chromatography (1)
- peripheral nerve (1)
- peripheral-blood lymphocytes (1)
- periphere Lymphozyten (1)
- personalized treatment (1)
- perspectives (1)
- pharmacology (1)
- phenobarbitale (1)
- phenotyping (1)
- pheochromocytoma cells (1)
- phopohrylierungsdefizient (1)
- phosducin (1)
- phosducin-like protein (PhLP) (1)
- phosphoglycolate phosphatase (1)
- phosphoglycolatephosphatase (1)
- phosphoinositides (1)
- photoaffinity labelling (1)
- phytohormones (1)
- placenta (1)
- plasma membrane (1)
- plasma membrane calcium ATPase (1)
- plötzlicher Herztod (1)
- pms2 (1)
- poly(ADP-ribosyl)ation (1)
- pore formation (1)
- pore-forming toxin (1)
- posttranslational modification (1)
- posttranslationale Modifikation (1)
- potent (1)
- pregnancy (1)
- primary aromatic amine (1)
- proliferation (1)
- protein (1)
- protein adducts (1)
- protein alkylation (1)
- protein design (1)
- protein-coupled receptors (1)
- protein-coupled-receptors (1)
- psoriasis (1)
- psychiatric disorders (1)
- psychosocial stress (1)
- psychosozialer Stress (1)
- purine derivatives (1)
- pyridoxal phosphatase (1)
- pyridoxal phosphatase (PDXP) (1)
- pyridoxal phosphate (1)
- pyrrolizidine alkaloids (1)
- quantitative assessments (1)
- radii (1)
- radiofrequency radiation (1)
- radioligand (1)
- radioligand binding (1)
- radiosensibilisation (1)
- rat pheochromocytoma cells (1)
- rats (1)
- reactive metabolites (1)
- reaktive Metabolite (1)
- reaktive Sauerstoffspezies (1)
- receptor (1)
- receptor binding (1)
- receptor pharmacology (1)
- receptor solubilization (1)
- receptor-G protein coupling (1)
- receptor-G protein coupling. (1)
- red blood cells (1)
- reduction of ERK1/2 phosphorylation (1)
- reduction of cells proliferation (1)
- regulation (1)
- relaxation (1)
- renal toxicity (1)
- repeated dose (1)
- reproductive and developmental toxicity (1)
- resistance (1)
- rezeptorvermittelte Endozytose (1)
- risk (1)
- risk-assesment (1)
- sGC (1)
- second extracellular loop (1)
- senecionine (1)
- seneciphylline (1)
- sensor (1)
- sensory physiology (1)
- serum (1)
- sex (1)
- sexual development (1)
- signaling microdomain (1)
- simulated digestion (1)
- single-molecule imaging (1)
- single-molecule microscopy (1)
- sister chromatid exch. (1)
- solid-phase extraction (1)
- solubilization (1)
- soluble guanylyl cyclase (1)
- sponges (1)
- spontaneously hypersensitive-rats (1)
- stabile Transfektion (1)
- stable transfection (1)
- staphilococci (1)
- statins (1)
- stomach (1)
- streptomyces (1)
- sub-Saharan Africa (1)
- sublinear (1)
- subtypes (1)
- sugars (1)
- sulfonylurea (1)
- susceptibility (1)
- synapses (1)
- synaptic plasticity (1)
- synergism (1)
- tMCAO (1)
- tandem mass-spectrometry (1)
- targets (1)
- terminale Niereninsuffizienz (1)
- testosterone production (1)
- tetrafluoropropene (1)
- therapeutic potential (1)
- thrombin (1)
- thyroid hormone (1)
- tierversuchsfrei (1)
- tissue (1)
- tolbutamide substrate (1)
- toxicity testing (1)
- toxicocinética (1)
- toxicokinetics (1)
- toxicology (1)
- trans-1 (1)
- trans-Golgi network (1)
- transcription (1)
- transgene Ratten (1)
- transgene rats (1)
- transgenic (1)
- transgenic animals (1)
- transgenic mice (1)
- triazolotriazine derivatives (1)
- trifluoropropionic acid (1)
- tuber (1)
- tumour (1)
- tumourpromotion (1)
- tyrosine phosphatase (1)
- ubiquitin (1)
- ultrastructure (1)
- urea (1)
- variocosities (1)
- vascular smooth muscle cells (1)
- vasculogenesis (1)
- vaskuläre glatte Muskelzellen (1)
- vav2 (1)
- vessel (1)
- vitamin b12 (1)
- vitamin-D-receptor (1)
- volume overload (1)
- warfarin polymorphisms (1)
- weight of evidence (1)
- yellow fluorescent protein (1)
- zweite extrazelluläre Domäne (1)
- µ-Opioid receptor (1)
- Östrogen (1)
- ß-adrenerge Rezeptoren (1)
- ß-adrenerge Signaltransduktion (1)
- ß-adrenergic Receptors (1)
- β-adrenergic receptors (1)
- β1-adrenoceptor/β1-adrenergic receptor (1)
- βAR (1)
- γ-H2AX (1)
Institute
- Institut für Pharmakologie und Toxikologie (407) (remove)
Sonstige beteiligte Institutionen
- Institut für Biopsychologie, Universität Dresden (1)
- Johns Hopkins School of Medicine (1)
- Johns Hopkins School of Medicine, Baltimore, MD, U.S. (1)
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V. (1)
- Max Delbrück Center for Molecular Medicine (1)
- Max-Delbrück-Center für molekulare Medizin, Berlin (1)
- Pharmakologie, Universität Bonn (1)
- Pharmazie, Universität Mailand (1)
- Universitätsklinikum Düsseldorf, Institut für Toxikologie (1)
Seit langem werden auf das β-adrenerge System wirkende Pharmaka, v.a. β1-Antagonisten und β2-Agonisten, therapeutisch eingesetzt, allerdings sind die pharmakologischen Eigenschaften dieser Stoffe an den drei bekannten β-adrenergen Subtypen teilweise nur unzureichend untersucht. Ein Ziel dieser Arbeit war es daher, vergleichbare pharmakologische Daten für Agonisten (Adrenalin, Noradrenalin, Isoprenalin, Fenoterol, Salbutamol, Salmeterol, Terbutalin, Formoterol, Broxaterol) und Neutrale und Inverse Antagonisten (Propranolol, Alprenolol, Atenolol, Metoprolol, Bisoprolol, Carvedilol, Pindolol, BRL 37344, CGP 20712, SR 59230A, CGP 12177, ICI 118551) an allen drei Subtypen von adrenergen Rezeptoren in einem zellbiologisch identischen Hintergrund zu gewinnen. Dazu stellten wir stabil transfizierte CHO-Zelllinien her, die die einzelnen humanen β-adrenergen Subtypen in vergleichbarer Menge exprimierten. Nach der pharmakologischen Charakterisierung der einzelnen Rezeptorsubtypen erfolgte die Affinitätsmessung von klinisch häufig eingesetzten wie auch experimentell verwendeten Substanzen mit dem unselektiven β-adrenergen Antagonisten 125I-CYP als Radioligand. Darüber hinaus untersuchten wir die β-adrenerg vermittelte Stimulation der Adenylylcyclase in isolierten Membranen dieser Zelllinien. Alle untersuchten Substanzen zeigten charakteristische Bindungs- und funktionale Eigenschaften. Wir konnten nachweisen, dass einige β2- bzw. β3-Agonisten an den anderen Subtypen inversen Agonismus zeigen. Zusätzlich konnten β1-Antagonisten mit agonistischer Aktivität an β2- und β3-AR gefunden werden. Die gewonnenen Daten können somit helfen, klinisch beobachtete Effekte, wie z.B. die unerwünschten Wirkungen der entsprechenden Medikamente, besser zu verstehen. Insbesondere die Ergebnisse am β3-AR sind als Referenz und Ausgangspunkt weiterer Studien an diesem noch relativ wenig untersuchten Rezeptor wertvoll.
Insulin ist ein essentielles Hormon im menschlichen Körper, welches für die Senkung der Blutglukosekonzentration, die Bildung von Energiespeichern und das Zellwachstum verantwortlich ist. Eine mit der Fehlregulation der Insulinproduktion einhergehenden Krankheit ist der Diabetes mellitus. Für diese Arbeit spielt der Typ 2 dieser Erkrankung eine wichtige Rolle. Es entwickelt sich bei Patienten mit diesem Typ des Diabetes mellitus langsam eine Insulinresistenz, die zunächst durch eine kompensatorische Überproduktion von Insulin charakterisiert ist. Dieser Zustand der Hyperinsulinämie kann Jahre bis Jahrzehnte andauern, ehe es zu einem Versagen der ß-Zellen des Pankreas und somit zu einer Hypoinsulinämie kommt. In dieser Arbeit war es Ziel herauszufinden, ob diese lange Zeit herrschende Hyperinsulinämie einen Einfluss auf die menschliche DNA hat. Die Genotoxizität von hohen Insulinkonzentrationen wurde in Hep-G2 Zellen, HT29 Zellen, sowie primären humanen peripheren Lymphozyten mithilfe des Comet Assays und des Mikrokerntests nachgewiesen. Oxidativer Stress bzw. dessen Reduzierung durch Antioxidantien und Inhibitoren wurde in HT29 Zellen mithilfe der DHE-Färbung detektiert. Diese Arbeit belegt dass sich Insulin schädigend auf das menschliche Genom in vitro auswirken kann. Eine besondere Relevanz haben die durchgeführten Experimente mit primären menschlichen Lymphozyten. Denn bei ihnen handelt es sich um Zellen, die im Gegensatz zu der auch genutzten humanen Leberkarzinomzelllinie Hep-G2 und der humanen Kolonkarzinomzelllinie HT29 nicht transformiert sind. Eine weitere wesentliche Erkenntnis dieser Arbeit ist, dass schon pathophysiologisch vorliegende Insulinkonzentrationen in der Lage sind Genomschädigungen in vitro zu induzieren. HT29 Zellen zeigten bei Kurzzeitbehandlung mit nur 1nM Insulin eine signifikante Erhöhung der DNA-Schädigung. Bei Langzeitexposition von 6 Tagen konnten schon 0,5nM signifikante DNA-Schäden hervorrufen. Diese durch Insulin hervorgerufenen Schäden könnten, falls sie so auch in vivo entstehen, bei Versagen von Reparaturmechanismen zur Entstehung von Mutationen und sich daraus entwickelnden Karzinomen beitragen. Aus diesem Grund war ein weiteres Ziel dieser Arbeit herauszufinden, ob bestimmte Antioxidantien oder Inhibitoren in der Lage sind die Insulin-induzierten Genomschädigungen zu verringern. Hierfür wurde Tempol, Apocynin, Plumbagin, VAS2870, Rotenone, PPP, HNMPA-(AM)3 und Wortmannin genutzt. Tatsächlich sind diese Substanzen in der Lage die durch Insulin hervorgerufene Schädigung zu reduzieren. Die positiven Ergebnisse dieser Arbeit könnten einen ersten Hinweis auf eine mögliche pharmakologische Intervention bei Hyperinsulinämie mit dem Ziel der Senkung des erhöhten Krebsrisikos geben. Eine wichtige Erkenntnis aus den Ergebnissen meiner Arbeit ist, dass die Reduzierung des oxidativen Stresses eine Reduzierung der Genomschädigung bewirkt. Die genutzten Substanzen Apocynin, Tempol, VAS2870 und Rotenone bewirkten in HT29 Zellen eine signifikante Reduzierung des durch Insulin ausgelösten oxidativen Stresses. Um aber genauere Aussagen über Möglichkeiten der Therapie bei Hyperinsulinämie zu treffen, sollten Folgestudien auch in vivo folgen, welche die in dieser Arbeit beschriebenen Effekte bestätigen.
Patienten mit erhöhten Aldosteronspiegeln zeigen eine gesteigerte Inzidenz für Malignome, insbesondere von Nierenzellkarzinomen. Das Ziel dieser Arbeit war es, die Aldosteron-vermittelte oxidative Nierenschädigung näher zu analysieren sowie die auf Zellebene gezeigte Beeinflussung der antioxidativen Schutzmechanismen im lebenden Organismus nachzuweisen und mögliche therapeutische Ansatzpunkte zu identifizieren. Dazu wurde ein Interventions-versuch über 28 Tage durchgeführt. Neben einer Aldosterongabe wurden folgende Interventionen verwendet: Spironolacton zur Blockade des Mineralkortikoid-Rezeptors (MR), Apocynin als Hemmstoff der NADPH-Oxidasen (Nox), L-NAME zur Blockade der NO-Synthasen (NOS), PDTC, einen Hemmstoff des Transkriptionsfaktors NF-kB sowie Sulforaphan, ein natürlicher Nrf2-Induktor. Eine weitere Gruppe erhielt Sulforaphan ohne additive Aldosterongabe. Die Nierenschäden wurden mittels histopathologischer Schädigungsscores und der Anzahl an DNA-Doppelstrangbrüche analysiert. Die Beeinflussung der antioxidativen Abwehr wurde durch die Aktivierung des Transkriptionsfaktors Nrf2 und durch die Quantifizierung antioxidativer Enzyme bestimmt.
Im Nierengewebe führte Aldosteron zu einer Zunahme von oxidativem Stress. Histologisch zeigte sich ein Anstieg von glomerulären Schäden. Auch kam es zu einer deutlichen Zunahme von Doppelstrangbrüchen der DNA. Des Weiteren konnten wir zeigen, dass Aldosteron auch in vivo zu einer Zunahme der Nrf2-Aktivität führte, wobei sich dies auf Proteinebene nicht in einer (dauerhaften) Synthesesteigerung von antioxidativen Enzymen wiederspiegelte und keinen ausreichenden Schutz des Nierengewebes bot. Für die Interventionsgruppen konnte keine signifikante Auswirkung auf das Vorliegen von oxidativem Stress gezeigt werden. Dies könnte an der Versuchsdauer bzw. an der gewählten Nachweismethode gelegen haben. Nichtsdestotrotz zeigte die Blockade der Nox durch Apocynin bzw. der NOS durch L-NAME eine effektive Reduktion der histologischen und genomischen Schäden. Die L-NAME-Gruppe wies dabei die höchsten Blutdruckwerte auf, diese waren auch zur Aldosterongruppe signifikant gesteigert. Die beobachteten Effekte waren folglich nicht durch den in der Aldosterongruppe erfolgten Blutdruckanstieg, sondern vielmehr durch den Anstieg von oxidativem Stress zu erklären. Ebenfalls blieb die Nrf2-Aktivität bei der Gabe von Apocynin und L-NAME weitgehend auf Kontrollniveau, was dafürspricht, dass der in der Aldosterongruppe messbare Nrf2-Anstieg am ehesten als Reaktion auf chronisch erhöhten oxidativen Stress erfolgte, welcher durch die Interventionen ausblieb. Die Blockade von NF-κB mittels PDTC führte zu vergleichbaren Effekten wie Apocynin und L-NAME. Das deutet darauf hin, dass Aldosteron über die Aktivierung von NF-κB die vermehrte Synthese von pro-oxidativen Enzymen wie Nox und NOS anregt. Die Gabe von Spironolacton hatte den stärksten protektiven Effekt, sowohl auf histologische Veränderungen als auch auf das Entstehen von DNA-Doppelstrangbrüchen, wobei die Nrf2-Aktivität in dieser Gruppe ebenfalls auf Kontrollniveau blieb. Die Aldosteroneffekte wurden folglich über den MR vermittelt. Eine additive Nrf2-Induktion mittels Sulforaphan konnte auch keinen (dauerhaften) Effekt auf die Synthese antioxidativer Enzyme zeigen. Dennoch zeigte diese Gruppe einen ähnlich effektiven Schutz vor den oxidativen Nierenschäden wie die Gabe von Spironolacton. Vieles spricht dafür, dass die Wirkung von Sulforaphan dabei über seine Wirkung als direktes Antioxidans bzw. Radikalfänger und nicht über den Nrf2-Weg zu erklären ist.
Aldosteron führt in der Niere über oxidativen Stress zu glomerulärer Fibrose und DNA-Schäden. Das könnte eine Erklärung für die gesteigerte Inzidenz von Nierenzellkarzinomen in Patienten mit erhöhten Aldosteronspiegeln darstellen. Unsere Ergebnisse sprechen dafür, dass Aldosteron über eine Signalkaskade über den MR zu einer Aktivierung von Nox und NOS führt. Der Aktivierung des Transkriptionsfaktors NF-κB scheint dabei durch die Synthese pro-oxidativer Enzyme eine Art Verstärker-Effekt zuzukommen. Als Reaktion auf den durch Aldosteron gesteigerten oxidativen Stress kommt es zu einer Aktivierung des antioxidativen Transkriptionsfaktors Nrf2, jedoch ohne dass dies zu einem ausreichenden Schutz des Nierengewebes führt. Mögliche therapeutische Ansatzpunkte für einen Schutz vor den durch Aldosteron vermittelten oxidativen Nierenschäden scheinen eher innerhalb der Aldosteronsignalkaskade, insbesondere in der Blockade des MR, als in der antioxidativen Abwehr zu liegen.
In their role as second messengers, cyclic nucleotides such as cAMP have a variety of intracellular effects. These complex tasks demand a highly organized orchestration of spatially and temporally confined cAMP action which should be best achieved by compartmentalization of the latter. A great body of evidence suggests that cAMP compartments may be established and maintained by cAMP degrading enzymes, e.g. phosphodiesterases (PDEs). However, the molecular and biophysical details of how PDEs can orchestrate cAMP gradients are entirely unclear. In this paper, using fusion proteins of cAMP FRET-sensors and PDEs in living cells, we provide direct experimental evidence that the cAMP concentration in the vicinity of an individual PDE molecule is below the detection limit of our FRET sensors (<100nM). This cAMP gradient persists in crude cytosol preparations. We developed mathematical models based on diffusion-reaction equations which describe the creation of nanocompartments around a single PDE molecule and more complex spatial PDE arrangements. The analytically solvable equations derived here explicitly determine how the capability of a single PDE, or PDE complexes, to create a nanocompartment depend on the cAMP degradation rate, the diffusive mobility of cAMP, and geometrical and topological parameters. We apply these generic models to our experimental data and determine the diffusive mobility and degradation rate of cAMP. The results obtained for these parameters differ by far from data in literature for free soluble cAMP interacting with PDE. Hence, restricted cAMP diffusion in the vincinity of PDE is necessary to create cAMP nanocompartments in cells.
The effects of barbiturates on the GABA·receptor complex and the A\(_1\) adenosine receptor were studied. At the GABA-receptor complex the barbiturates inhibited the binding of [\(^{35}\)S]t-butylbicyclophosphorothionate [\(^{35}\)S]TBPT) and enhanced the binding of [\(^3\)H]diazepam. Kinetic and saturation experiments showed that both effects were allosteric. Whereas all barbiturates caused complete inhibition of [\(^{35}\)S]TBPT binding, they showed varying degrees of maximal enhancement of [\(^3\)H]diazepam binding; (±)methohexital was idenafied as the most efficacious compound for this enhancement. At the A\(_1\) adenosine receptor all barbiturates inhibited the binding of [\(^3\)H]N\(^6\)-phenylisopropyladenosine (\(^3\)H]PIA) in a competitive manner. The comparison of the effects on [\(^3\)H]diazepam and [\(^3\)H]PIA binding showed that excitatory barbiturates interact preferentially with the A\(_1\) adenosine receptor, and sedative/anaesthetic barbiturates with the GABA-receptor complex. It is speculated that the interaction with these two receptors might be the basis of the excitatory versus sedative/ anaesthetic properties of barbiturates.
Human platelet membranes were solubilized with the zwitterionic detergent CHAPS (3-[3-(cholamidopropyl)dimethylammonio]- 1-propanesulfonate) and the solubilized extract subjected to gel ftltration. Binding of the adenosine receptor agonist [\(^3\)H]NECA (5'-N-ethylcarboxamidoadenosine) was measured to the eluted fractions. Two [\(^3\)H]NECA binding peaks were eluted, the first of them with the void volume. This first peak represented between 10% and 25% of the [\(^3\)H]NECA binding activity eluted from the column. It bound [\(^3\)H]NECA in a reversible, saturable and GTPdependent manner with an affinity of 46 nmol/1 and a binding capacity of 510 fmol/mg protein. Various adenosine receptor ligands competed for the binding of [\(^3\)H]NECA to the frrst peak with a pharmacological proftle characteristic for the A\(_2\) adenosine receptor as determined from adenylate cyclase experiments. In contrast, most adenosine receptor ligands did not compete for [\(^3\)H]NECA binding to the second, major peak. These results suggest that a solubilized A\(_2\) receptor-Gs protein complex of human platelets can be separated from other [\(^3\)H]NECA binding sites by gel filtration. This allows reliable radioligand binding studies of the A2 adenosine receptor of human plate1ets.
Adenosine modulates a variety of physiological functions via membrane-bound receptors. These receptors couple via G proteins to adenylate cyclase and K+channels. The A1 subtype mediates an inhibition of adenylate cyclase and an opening of K+-channels, and the A2 subtype a Stimulation of adenylate cyclase. Both subtypes have been characterized by radioligand binding. This has facilitated the development of agonists and antagonists with more than 1000-fold A1 selectivity. A1-selective photoaffinity labels have been used for the biochemical characterization of A1 receptors and the study of their coupling to adenylate cyclase. Such selective ligands allow the analysis of the involvement of adenosine receptors in physiological functions. Selective interference with adenosine receptors provides new pharmacological tools and eventually new therapeutic approaches to a number of pathophysiological states.
The binding of \([^3H]\)phenobarbital to rat brain membranes was studied in order to determine its characteristics and specificity. The binding reaction was rapid and occurred at sites of low affinity. \((K_d = 700 μM)\) and very high density \((B_{max} = 2.7 nmoll/mg protein)\). It was unaffected by temperature changes from O°C to 95°C and was maximal at pH 5. Detergents in low concentrations markedly decreased the binding, apparently without solubilizing the binding sites. It is concluded that the binding of \([^3H]\) phenobarbital is a rather non-specific interaction with the plasma membrane.
Tbe 2',3'-dideoxy analogue of the potent A\(_1\) receptor agonist, N\(^6\)-cyclohexyladenosine (CHA), was synthesized as a potential antagonist for the A\(_1\) adenosine receptor. In sturlies on adenylate cyclase 2',3'-dideoxy-N\(^6\)-cyclohexyladenosine (ddCHA) did not show agonist properties at A\(_1\) or at A\(_2\) receptors. However, it antagonized the inhibition by R-PIA of adenylate cyclase activity of fat cell membranes via A\(_1\) receptors with a K\(_i\) value of 13 \(\mu\)M. ddCHA competed for the binding of the selective A1 receptor antagonist, [\(^3\) HJ8-cyclopentyl-1,3-dipropylxantbine ([\(^3\)H]DPCPX), to rat brain membranes with a K\(_i\) value of 4.8 \(\mu\)M; GTP did not affect the competition curve. In contrast to the marked stereoselectivity of the A\(_1\) receptor for the cx- and the natural ß-anomer of adenosine, the cx-anomer of ddCHA showed a comparable affinity for the A\(_1\) receptor (K\(_i\) value 13.9 \8\mu\)M). These data indicate that the 2'- and 3'-hydroxy groups of adenosine and its derivatives are required foragonist activity at and high affinity binding to A\(_1\) adenosine receptors and for the distinction between the cx- and ß-forms.
Barbiturates in pharmacologically relevant . concentrations inhibit binding of (R)-\(N^6\)-phenylisopropyl[\(^3\)H]adenosine ([\(^3\)H]PIA) to solubilized A\(_1\) adenosine receptors in a concentration-dependent, stereospecific, and competitive manner. K\(_i\) values are similar to those obtained for membrane-bound receptors and are 31 \(\mu\)M for ( ± )-5-(1 ,3-dimethyl)-5-ethylbarbituric acid [( ± )DMBB] and 89 \(\mu\)M for ( ± )-pentobarbital. Kinetic experiments demoostrate that barbiturates compete directly for the binding site of the receptor. The inhibition of rat striatal adenylate cyclase by unlabelled (R)-\(N^6\)-phenylisopropyladenosine [(R)-PIA] is antagonized by barbiturates in the same concentrations that inhibit radioligand binding. The Stimulation of adenylate cyclase via A\(_2\) adenosine receptors in membranes from NIE 115 neuroblastoma cells is antagonized only by 10-30 times higher concentrations of barbiturates. lt is concluded that barbiturates are selective antagonists at the A1 receptor subtype. In analogy to the excitatory effects of methylxanthines it is suggested that A\(_1\) adenosine receptor antagonism may convey excitatory properties to barbiturates. Key Words: Adenosine receptors-Barbiturates - Adenylate cyclase-Receptor solubilization-[3H]PIA binding-N1E 115 cells. Lohse M. J. et al. Barbiturates are selective antagonists at A1 adenosine receptors.
The properties of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) as an antagonist ligand for A\(_1\) adenosirre receptors were examined and conipared with other radioligands for this receptor. DPCPX competitively antagonized both the inhibition of adenylate cyclase activity via A\(_1\) adenosirre receptors and the stimulationvia A\(_2\) adenosirre receptors. The K\(_i\)-values of this antagonism were 0.45 nM at the A\(_1\) receptor of rat fat cells, and 330 nM at the A\(_2\) receptor of human platelets, giving a more than 700-fold A\(_1\)-selectivity. A similar A\(_1\)-selectivity was determined in radioligand binding studies. Even at high concentrations, DPCPX did not significantly inhibit the soluble cAMPphosphodiesterase activity of human platelets. [\(^3\)H]DPCPX (105 Ci/mmol) bound in a saturable manner with high affinity to A\(_1\) receptors in membranes of bovine brain and heart, and rat brain and fat cells (K\(_D\) -values 50-190 pM). Its nonspecific binding was about 1% of total at K\(_D\) , except in bovine myocardial membranes (about 10%). Binding studies with bovine myocardial membranes allowed the analysis of both the high and low agonist affinity states of this receptor in a tissue with low receptor density. The binding properties of [\(^3\)H]DPCPX appear superior to those of other agonist and antagonist radioligands for the A\(_1\) receptor.
2-Chloro-N\(^6\)-cyclopentyladenosine: a highly selective agonist at A\(_1\) adenosine receptors
(1988)
2-Chloro-N\(^6\)-cyclopentyladenosine (CCPA) was synthesized as a potential high affinity ligand for At adenosine receptors. Binding of [\(^3\)H]PIA to A1 receptors of rat brain membranes was inhibited by CCP A with a Ki-value of 0.4 nM, compared to a Ki-value of 0.8 nM for the parent compound N\(^6\)-cyclopentyladenosine (CPA). Binding of [\(^3\)H]NECA to A\(_2\) receptors of rat striatal membranes was inhibited with a Ki-value of 3900 nM, demonstrating an almost 10,000-fold A\(_1\)-selectivity of CCPA. CCP A inhibited the activity of rat fat cell membrane adenylate cyclase, a model for the A\(_1\) receptor, with an IC\(_{50}\)-value of 33 nM, and it stimulated the adenylate cyclase activity of human platelet membranes with an EC\(_{50}\)-value of 3500 nM. The more than 100-fold A\(_1\)-selectivity compares favourably with a 38-fold selectivity of CPA. Thus, CCPA is an agonist at A\(_1\) adenosine receptors with a 4-fold higher selectivity and 2-fold higher affinity than CPA, and a considerably higher selectivity than the standard At receptor agonist R-N\(^6\) -phenylisopropyladenosine (R-PIA). CCP A represents the agonist with the highest selectivity for A\(_1\) receptors reported so far.
1 Adenosine and its metabolically stable analogue N.etbyl-carboxamidoadenosine (NECA) enhance histamine release from rat peritoneal mast cells when tbese are stimulated by calciummobilizing agents. NECA and adenosine shift the concentration-response curve of tbe calcium ionophore A23187 to lower concentrations. 2 The potencies of NECA or adenosinein enhancing A23187-induced histamine release are dependent on the Ievel of stimulated release in tbe absence of adenosine analogues. At high Ievels of release their potencies are up to 20 times higher than at low Ievels. Consequently, averaged concentration-response curves of adenosine and NECA for enhancing bistamine release are shallow. 3 The adenosine transport blocker S-(p-nitrobenzyl)-6-thioinosine (NBTI) has no effect by itself at low Ievels of stimulated histamine release, but abolishes the enhancing effect of adenosine. At high Ievels of release, however, NBTI alone enhances the release of histamine. 4 lt is concluded that adenosine and calcium reciprocally enhance the sensitivity of the secretory processes to the effects of the other agent. The Ievels of intracellular adenosine obtained by trapping adenosine inside stimulated mast cells are sufficient to enhance histamine release substantially, suggesting that this effect may play a physiological and pathophysiological role.
Mast cells release histamine and other mediators of allergy in response to stimulation of their IgE receptors. This release is generally thought to be mediated by an elevation of cytosolic \(Ca^{2+}\). Recent evidence suggests that there might be factors that modulate the coupling between \(Ca^{2+}\) levels and mediator release. The present report identifies adenosine as one such modulator. Adenosine and several of its metabolically stable analogues were shown to enhance histamine release from rat peritoneal mast cells in response to stimuli such as concanavalin A. Metabolizing endogenous adenosine with adenosine deaminase dampened the response to stimuli, whereas trapping endogenous adenosine inside mast cells with nucleoside-transport inhibitors markedly enhanced stimulated histamine release. The metabolically stable adenosine analogue 5' -(N-ethylcarboxamido)adenosine (NECA) did not affect the initial steps in the sequence from IgE-receptor activation to mediator release, which are generation of inositol trisphosphate and increase of cytosolic \(Ca^{2+}\). However, NECA did enhance the release induced in ATP-permeabilized cells by exogenous \(Ca^{2+}\), but it had no effect on the release induced by phorbol esters. These data suggest that adenosine sensitizes mediator release by a mechanism regulating stimulus-secretion coupling at a step distal to receptor activation and second-messenger generation.
It has previously been shown that covalent incorporation of the photoreactive adenosine derivative (R)-2-azido-N6-p-hydroxyphenytisopropyladenosine [(R)-AHPIA] into the A, adenosine receptor of intact fat cells leads to a persistent activation of this receptor, resulting in a reduction of celular cAMP Ieveis [Mol. Pharmacol. 30:403-409 (1986)]. In contrast, covalent incorporation of (R)-AHPIA into human platelet membranes, which contain only stimulatory A2 adenosine receptors, reduces adenytate cyclase Stimulation via these receptors. This effect of (R)-AHPIA is specific for the A2 receptor and can be prevented by the adenosine receptor antagonist theophylline. Binding studies in-dicate that up to 90% of A2 receptors can be blocked by photoincorporation of (R)-AHPIA. However, the remaining 10-20% of A2 receptors are sufficient to mediate an adenylate cyclase Stimulation of up to SOOk of the control value. Similarly, the activation via these 10-20% of receptors occurs with a halflife that is only 2 times Ionger than that in control membranes. This indicates the presence of a receptor reserve, with respect to both the extent and the rate of adenytate cyclase Stimulation. These observations require a modification of the models of receptor-adenytate cyclase coupling, which is described in the accompanying paper [Mol. Pharmacol. 39:524-530 (1991)].
Barbiturates inhibit binding of radioligands to A 1(Ri) adenosine receptors of rat brain membranes. This inhibition is dose-dependent and stereospecific and occurs in the range of pharmacologically active concentrations. The displacement of radiolabelled A1antagonists by barbiturates is not modified by GTP, indicating that barbiturates might act as antagonists at this receptor. This action of barbiturates does not seem to be related to the binding of barbiturates to plasma membranes, as the latter process has different characteristics. Barbiturates also inhibit the binding of radioligands to solubilized A1receptors, and saturation and kinetic experiments suggest that this is due to a competitive antagonism. These results indicate that barbiturates interact with the recognition site of the A1adenosine receptor.
The ligand-binding subunit ofthe A1 adenosine receptor has been identified in membranes with the photoaffinity Iabel R-2-azido-N6-p-hydroxyphenylisopropyladenosine (R-AHPIA). Covalent labelling ofthe A1 receptor can also be achieved in intact cells. The dissociation of the radioiodinated label (1251-AHPIA) from isolated rat fat cells was incomplete after UV irradiation, leaving about 20°/o of irreversible specific binding. Such covalent labelling of the receptor led to a concentration-dependent reduction of cellular cyclic AMP levels. This persistent effect of covalent labeHing occurred with an IC50 value of 9 nM, as compared to an IC50 value of 0.9 nM for the direct reduction of cyclic AMP Ievels by the ligand. The difference in the IC5o values can be explained by assuming spare receptors. This hypothesis was verified in binding studies using [ 3HJPIA as a radioligand. R-AHPIA inhibited binding of [3H)PIA to intact fat cells with a K1 value of about 20 nM, which is about 20 tim es high er than the corresponding IC50 value of cyclic AMP reduction. These data show that the A1 receptor is activated according to the occupancy theory. The high sensitivity of the activation in intact ceJis is due to a large number of spare receptors.
The binding of agonists and antagonists to a2-adrenergic receptors of human platelets was studied. The receptors showed homogeneaus affinities for antagonists but two affinity states for the agonist (-)-epinephrine, which were modulated by guanine nucleotides. Van't Hoffplots of antagonist binding had a break point at about 18° and considerable diversity between 18° and 0°. Agonist binding to both affinity states showed a similar break point; agonist binding to the high affinity state was characterized by a large entropy component compared to the low affinity state. This entropy component was reduced at higher concentrations of sodium, indicating that it may be due to Iiberation of sodium ions. Measurements of the fluorescence of 1-anilin-8-naphthalenesulfonate showed thermotropic phase transitions of theplatelet membranes at about 17°. The transition temperature was decreased to about 12° by addition of 1 0 mM octanoic acid. Octanoic acidalso shifted the break points of the van't Hoffplot of antagonist and low affinity agonist binding from 18° to 12°. High affinity agonist binding, however, remained unchanged. It is concluded that agonist-specific thennodynamic characteristics of ligand binding to a2-receptors of human platelets can only be investigated by regarding differences between high and low affinity agonist binding. These differences include an entropy increase upon Iigand binding, which is in part due to enhanced liberation of sodium ions, and a loss of sensitivity to fluidity changes in the outer layer of the plasma membrane.
Cancer and heart disease are leading causes of morbidity and mortality worldwide. These diseases have common risk factors, common molecular signaling pathways that are central to their pathogenesis, and even some disease phenotypes that are interdependent. Thus, a detailed understanding of common regulators is critical for the development of new and synergistic therapeutic strategies. The Raf kinase inhibitory protein (RKIP) is a regulator of the cellular kinome that functions to maintain cellular robustness and prevent the progression of diseases including heart disease and cancer. Two of the key signaling pathways controlled by RKIP are the β-adrenergic receptor (βAR) signaling to protein kinase A (PKA), particularly in the heart, and the MAP kinase cascade Raf/MEK/ERK1/2 that regulates multiple diseases. The goal of this review is to discuss how we can leverage RKIP to suppress cancer without incurring deleterious effects on the heart. Specifically, we discuss: (1) How RKIP functions to either suppress or activate βAR (PKA) and ERK1/2 signaling; (2) How we can prevent cancer-promoting kinase signaling while at the same time avoiding cardiotoxicity.
Ausgangspunkt der Arbeit ist die klinische Beobachtung, dass Patienten mit arteriellem Hypertonus vermehrt Nierenerkrankungen entwickeln. Dabei zeigten sich in der Subgruppenanalyse vor allem erhöhte Inzidenzen der Niereninsuffizienz und der Nierenzellkarzinome. Als möglicher Pathomechanismus steht das Renin-Angiotensin-Aldosteron-System (RAAS-System) im Vordergrund. Dabei wird postuliert, dass erhöhte Angiotensin II-Spiegel zu einem Missverhältnis zwischen den Oxidations- und Reduktionspartnern in der Zelle führen, wodurch sich das oxidative Potential der Zelle ändert, und es vermehrt zur Bildung von Radikalen (ROS) kommt, die meist ungepaarte Elektronen in der Valenzschale oder instabile Verbindungen enthalten, wodurch sie besonders reaktionsfreudig mit Proteinen, Lipiden, Kohlenhydraten und auch der DNA interagieren. In der Folge kommt es zu DNA-Veränderungen in Form von Doppel- oder Einzelstrangbrüchen, DNA-Protein-Crosslinks, Basenmodifikationen und Basenverlusten, wodurch sich ein hohes mutagenes Potential ergibt. Dieser Ansatz zur Pathophysiologie bestätigte sich auch an den hier verwendeten porkinen Nierenzellmodell. Dabei zeigte sich nicht nur eine Veränderung der genomischen Stabilität nach Exposition gegenüber erhöhten Angiotensin II-Spiegeln, sondern auch eine Veränderung der DNA in Abhängigkeit von der Expositionsdauer der Zellen. Als nächster Schritt konnte die Modulation der Transkriptionsfaktoren Nrf 2 und NF-κB durch die Behandlung mit Angiotensin II und Sulforaphan nachgewiesen werden. Bei der Behandlung mit Sulforaphan ließ sich eine Nrf 2-Induktion nachweisen mit vermehrter Expression von antioxidativen und detoxifizierender Enzyme. Weiterhin zeigte sich im Rahmen der Behandlung erniedrigte NF-κB-Level. Bei der Modulation durch Angiotensin II stellte sich zunächst ein signifikant erniedrigtes Level an Nrf 2 in den Zellen dar, das im Verlauf von 24 Stunden anstieg und konsekutiv ließ sich eine maximale Proteinexpression zwischen 24 und 48 Stunden messen. Weiterhin wiesen die Zellen, die mit Angiotensin II behandelt wurden, erhöhte NF-κB Mengen/Zelle auf. Zudem zeigte sich der Einfluss erhöhter Glucosekonzentrationen auf eine progrediente genomischen Instabilität, die Veränderung der Transkriptionsfaktoren mit erhöhter Nrf 2-Induktion und mit Deregulation des Transkriptionsfaktors NF-κB wurde durch die Behandlung mit Sulforaphan nachgewiesen. Aufgrund dieser Rolle in der Tumorgenese sind mittlerweile einige Bestandteile des NF-κB- und des Nrf 2-Signalweges und auch Nrf 2-Aktivatoren wie Sulforaphan wichtige Zielstrukturen für die Entwicklung neuer Medikamente und Therapieoptionen. Besonders zeigt sich hierbei die Wichtigkeit bei Diabetes induzierten kardiovaskulären Folgeschäden mit frühzeitiger medikamentöser Behandlung.
Dose-response relationship and low dose extrapolation in chemical carcinogenesis [commentary]
(1990)
Data supporting various dose-respome relationships in chemical carcinogenesis are summarized. General principles are derived to explain the relationships between exposure dose, JI>NA adduct Ievel, induction of genetic changes, and tumor incidence. Some mechanistic aspects of epigenetic carcinogens (stimulation of ceU division and maldlfl'erentlation) are analyzed in a similar way. In a bomogeneous pnpulation, non-linearities are frequent. They are due to pbenomena of induction or saturation of enzymatic activities and to the multi-step nature of carcinog~: if a carcinogen acce1erates more than one step, the SUperposition of the dose- response curves for the indJvidual steps can result in an exponential relationship. A fourth power of the dose was the maximum seen in animals (fonnaldehyde). At the lowest dose Ievels, a proportionality between dose and tumor induction is postulated independent of the mechanism of action if the carcinogen aceeierotes the endogenous proass responsible for spootaneous tumor formation. Low-dose thresholds are expected only for situations where the carcinogen acts in a way that has no endogenous counterpart. Epidemiologfcal studies in humans show linear dose- response curves in all but two investigations. The difference from the strongly nonlinear slopes ·seen in animal studies could be due to the heterogeneity of the human population: if the individual sensitivity to a carcinogen is governed by a large number of genetic and Iife-style factors, the non-linea.rities will tend to cancel each other out and the dose- response curve becomes 'quasi-linear'.
A list ofendogenaus DNA·damaging agents and processes is given. Endogenaus e/ectrophiles are found with the cosubstrates of physiological transfer reactions (S-adenosylrnethionine for methylation, A TP for phosphorylation, NAD\(^+\) for ADP-ribosylation, acetyl CoA for acetylation). Aldehyde groups (glyceraldehyde- 3-phosphate, formaldehyde, open forms of reducing sugars, degradation products of peroxidation) or alkylating degradation products derived from endogenaus nitrose compounds represent additional possibilities. Radical-forming reactions include leakage of the superoxide anion radical from terminal cytochromes and redox cycles, hydroxyl radical formation by the Fenton reaction from endogenaus hydrogen peroxide, and the formation of lipid peroxides. Genetic instability by spontaneaus deaminations and depurinations as well as replicative instability by tautomer errors andin the presence of mutagenic metal ions represent a third important dass of endogenaus genotoxic processes. The postulated endogenaus genotoxicity could form the mechanistic basis for what is called 'spontaneous' tumor incidence and explain the possibility of an increased tumor incidence after treatment of animals with non-genotoxic compounds exhibiting tumor-promoting activity only. Individual differences are expected to be seen also with endogenaus DNA damage. The presence of endogenaus DNA darnage implies that exogenaus DNAcarcinogen adducts give rise to an incremental darnage which is expected to be proportional to the carcinogen dose at lowest Ievels. An increased tumor risk due to exposure to exogenaus genotoxic carcinogens could therefore be assessed in terms of the background DNA damage~ for instance in multiples of the mean Ievel or of the interindividual variability in a population.
The covalent binding of chemical carcinogens to DNA of mammalian organs is expressed per unit dose, and a 'Covalent-Binding Index', CBI, is defined. CBI for various carcinogens span over 6 orders of magnitude. A similar range is observed for the carcinogenic potency in long-term bioassays on carcinogenicity. For the assessment of a risk from exposure to a carcinogen, the total DN A darnage can be estimated if the actual dose is also accounted for. A detailed description is given for planning and performing a DNA-binding assay. A complete literature survey on DNA binding in vivo (83 compounds) is given with a calculation of CBI, where possible, 153 compounds are listed where a covalent binding to any biological macromolecule has been shown in vivo or in vitro. Recent, so far unpublished findings with aflatoxin Mh macromolecule- bound aflatoxin Bh ·diethylstilbestrol, and 1,2-epithiobutyronitrile are included. A comparison of CBI for rat-liver DNA with hepatocarcinogenic potency reveals a surprisingly good quantitative correlation. Refinements for a DN A-binding assay are proposed. Possibilities and Iimitations in the use of D NA binding in chemical carcinogenesis are discussed extensively.
It was the aim of this investigation to determine whether or not covalent binding of di(2-ethylhexyl) phthalate (DEHP) to rat liver DNA could be a mechanism of action contributing to the observed induction of liver tumors after lifetime feeding of rodents with high doses of DEHP. DEHP radiolabeled in different positionswas administered orally to female F344 rats with or without pretreatment for 4 weeks with 1% unlabeled DEHP in the diet. Livu DNA was isolated after 16 hr and analyzed for radioattivity. Administration of [\(^{14}\)C]carboxylate unabeled DEHP resulted in no measurable DNA radioactivity. With DEHP [\(^{14}\)C]· and [\(^{3}\)H]. labeled in the alcohol moiety as well as with 2-ethyl[1-\(^{14}\)C]hexanol, radioactivity was clearly measurable in the DNA. HPLC analysis of enzyme-degraded DNA relvealed that the normal nucleosides had incorporated radiolabel whereas no radioactivity was detectable in those fractions where the carcinogen-modified nucleoside adducts are expected. A quantitative evaluation of the negative data in terms of a Iimit of detection for a covalent binding Index (CBJ) indicates that covalent interaction with DNA is highly unlikely to be the mode of tumorigenic action of DEHP in rodents.
Investigation of covalent DNA binding in vivo provided evidence for whether a test substance can be activated to metabolites able to reach and react with DNA in an intact organism. Fora comparison of DNA binding potencies of various compounds tested under different conditions, a normalization of the DNA lesion with respect to the dose is useful. A covalent binding index, CBI = (\(\mu\)mol chemical bound per mol DNA nucleotide )/(mmol chemical administered per kg body weight) can be determined for each compound. Whether covalent DNA binding results in tumor formation is dependent upon additional factors specific to the cell type. Thus far, all compounds which bind covalently to liver DNA in vivo have also proven tobe carcinogenic in a long-term study, although the liver was not necessarily the target organ for tumor growth. With appropriate techniques, DNA binding can be determined in a dose range which may be many orders of magnitude below the dose Ievels required for significant tumor induction in a long-term bioassay. Rat liver DNA bindingwas proportional to the dose of aflatoxin B1 afteroral administration of a dose between 100 \(\mu\)g/kg and 1 ng/kg. The lowest dose was in the range of generat human daily exposures. Demonstration of a lack of liver DNA binding (CBI<0.1) in vivo for a carcinogenic, nonmutagenic compound is a strong indication for an indirect mechanism of carcinogenic action. Carcinogens of this class do not directly produce a change in gene structure or function but disturb a critical biochemical control mechanism, such as protection from oxygen radicals, control of cell division, etc. Ultimately, genetic changes are produced indirectly or accumulate from endogenaus genotoxic agents. The question of why compounds which act via indirect mechanisms are more likely to exhibitanonlinear rangein the dose-response curve as opposed to the directly genotoxic agents or processes is discussed.
Formaldehydeis an electrophilic molecule able to crosslink DNA and protein. It has been found to induce tumors in the nasal epithelium in rodents. The safety margin between the maximum tolerated FA concentration in the work place and the concentration found to be tumorigenic in animal studies is very small. Because FA is produced endogenously as a result of a variety of oxidative demethylations, the assessment of the tumor risk from exogenaus FA exposure has tobe related quantitatively to the level of DNA-protein crosslinks induced by endogenaus FA generation. It is reported here that the high level of endogenaus FA formed in the liver after a large dose of methanol or of aminopyrine did not lead to any observable increase in DNA-protein crosslinks. Using positive and negative control data from in vitro incubations of liver homogenate with FA or methanol it is estimated that the endogenous level of DNA damage in the liver must be more than three orders of magnitude below the damage observed at tumorigenic concentrations for the rat nose. The fact that FA is formed endogenously cannot, therefore, be used to claim that exogenous FA merely leads to a negligible increase in DNA damage.
Ich habe versucht darzulegen, daß mechanistische Überlegungen zur Extrapolation der Dosis-WirkungsBeziehung herangezogen werden können. Ein nichtlinearer Verlauf ist nicht nur bei den epigenetischen Kanzerogenen wahrscheinlich, sondern auch bei den DNA-bindenden. Echte Schwellen sind aber nur in solchen Fällen zu erwarten, wo kein endogenes Korrelat besteht. Immerhin können auch steile Nichtlinearitäten zu einer drastischen Risikoreduktion führen, so daß die Anstrengungen dahin gehen sollten, die Steigung und den Bereich des überproportionalen Abfalls experimentell zu zeigen. In einer heterogenen Population kann die 0 0- sis-Wirkungs-Kurve zusätzliche "Wellen" bekommen und wird dadurch grundsätzlich flacher. Im Extremfall ergibt sich eine lineare Dosis-Wirkungs-Beziehung unabhängig vom Wirkmechanismus des Kanzerogens. Diese Proportionalität zwischen tiefster Dosis und Effekt wird bei genotoxischen Kanzerogenen aus mechanistischen Gründen schon für eine homogene Population postuliert, doch kann dies in einer heterogenen Population auch bei epigenetischen Kanzerogenen in Frage kommen.
no abstract available
Many mutagens and carcinogens act via covalent interaction of metabolic intermediates with DNA in the target cell. This report groups those structural elements which are often found to form the basis for a metabolism to such chemically reactive metabolites. ~mpounds which are chemically reactive per se and which do not require metabolic activation form group 1. Group 2 compri~es of olefins and aromatic hydrocarbons where the oxidation via an epoxide can be responsible for the generation of reactive species. Aromatic amines, hydrazines, and nitrosamirres form group 3 requiring an oxidation of a nitrogen atom or of a carbon atom in alpha position to a nitrosated amine. Group 4 compounds are halogenated hydrocarbons which can either give rise to radicals or can form an ·olefin (group 2) upon dehydrohalogenation. Group 5 compounds depend upon some preceding enzymatic activity either not available in the target cell or acting on positions in the molecule which are not directly involved in the subsequent formation of electrophilic atoms. Examples for each group are taken from the "List of Chemieals and Irrdustrial Processes Associated with Cancer in Humans" as compiled by the International Agency for the Research on Cancer, and it is shown that 91% of the organic carcinogens would have been detected on the basis of structural elements characteristic for group 1-5. As opposed to this very high sensitivity, the specificity ( the true negative fraction) of using this approach as a short-term test for carcinogenicity is shown to be bad because detoxification pathways have so far not been taken into account. These competing processes are so complex, however, that either only very extensive knowledge about pharmacokinetics, stability, and reactivity will be required or that in vivo systems have to be used to predict, on a quantitative basis, the darnage expected on the DNA. DNA-binding experiments in vivo are presented with benzene and toluene to demonstrate one possible way for an experimental assessment and it is shown that the detoxification reaction at the methyl group available only in toluene gives rise to a reduction by at least a factor of forty for the binding to rat liver DNA. This quantitative approach available with DNA-binding tests in vivo, also allows evaluation as to whether reactive metabolites and their DNA binding are always the most important single activities contributing to the overall carcinogenicity of a chemical. With the example of the livertumor inducing hexachlorocyclohexane isomers it is shown that situations will be found where reactive metabolites are formed and DNA binding in vivo is measurable but where this activity cannot be the decisive mode of carcinogenic action. It is concluded that the lack of structural elements known to become potentially reactive does not guarantee the lack of a carcinogenic potential.
Mechanistic possibilitles responsible for nonlinear shapes of the dose-response relationship in chemical carcinogenesis are discussed. (i) Induction and saturation of enzymatic activation and detoxification processes and of DNA repair affect the relationship between dose and steady-state DNA adduct Ievel; (ii) The fixation of DNA adducts in the form of mutations is accelerated by stimulation of the cell division, for Jnstance due to regenerative hyperplasia at cytotoxic dose Ievels; (iii) The rate of tumor formation results from a superposition of the rates of the individual steps. It can become exponential with dose if more than one step is accelerated by the DNA damage exerted by the genotoxic carcinogen. The strongly sigmoidal shapes often observed for dose-tumor incidence relationships in animal bioassays supports this analysis. A power of four for the dose in the su~linear part of the curve is the maximum observed (formaldehyde). In contrast to animal experiments, epidemiological data ln humans rarely show a slgnificant deviation from linearity. The discrepancy might be explained by the fact that a I arge nu mber of genes contribute to the overall sensitivity of an individual and to the respective heterogeneity within the human population. Mechanistic nonlinearities are flattened out in the presence of genetic and life-style factors which affect the sensitivity for the development of cancer. For a risk assessment, linear extrapolation from the high-dose lncidence to the spontaneaus rate can therefore be approprlate in a heterogeneous population even if the mechanism of action would result in a nonlinear shape of the dose-response curve in a homogeneaus population.
~n order to investigate the role of the stimu~ation of ceU division for the initiation (and possi:bly promotion) of live·r tumors by chemical carcinogens, the incorporation of radiolabeUed thymidine into liver DNA was dete:rmined in male rats. Single doses of various level!s of af.latoxin 81, benzidine and carbon tetrachloride (aU known to be genotoxic via DNA binding} did not affect cell division, whereas several hepatoca:rcinogens known not to bind to DNA (alphaHCH, dofibrate, and 2,3;7,8-t!etrachlorodiibenzo~p~dioxin) gave rise to a dosedependent stimulation of Ii ver DNA synthesis within 24 h. An equation combining the infl.uences of mitotic stimu:lation, expressed as dose required to double the contro~ Ievei of DNA synthesis, and DNA binding potency, exp:ressed as t.he Covalent Binding Index, correliated weil with the cardnogenk potency for both dasses of hepatocardnogens.
[7-3H)Styrene 7,8-oxide was administered by oral gavage to male CD rats at a dose of 1.3 mg/kg. After 4 h, the forestomach was excised, DNA was isolated, purified to constant specific radioactivity and degraded nzymatically to the 3 '-nucleotides. Highperformance liquid chromatography fractions with the normal nucleotides contained most of the radiolabel, but a minute level of adduct label was also detccted. Using the units of the covalent binding index (micromoles adduct per mole DNA nucleotide)/(millimole chemical administered per kilogram body weight), a DNA binding potency of 1.0 was derived. A comparison of the covalent binding indices and carcinogenic potencies of other genotoxic forestarnach carcinogens showed that the tumorigenic activity of styrene oxide is unlikely to be purely genotoxic. Therefore, styrene oxide was compared with 3-tbutylhydroxyanisole (BHA) with respect to stimulation of cell proliferation in the forestomach. Male Fischer 344 rats were treated for four weeks at three dose levels of styrene oxide (0, 137, 275 and 550 mg/kg, three times per week by oral gavage) and BHA (0, 0.5, 1 and 2% in the diet); the highest doses had been reported to result in 84% and 22% carcinomas in the forestomach, respectively. Cell proliferation was assessed by incorporation of bromodeoxyuridine into DNA and immunohistochemical analysis. An increase in the lablling indexwas found in a11 treated animals. In the prefundic region of the forestomach, the labeHing index increased significantly, from 42% (controls) to 54% with styrene oxide and from 41 to 55% with BHA. Rats treated with BHA also had severe hyperplastic lesions in the prefundic region, i.e., at the location of BHA-induced forestomach carcinomas. The number of cells per millimetre of section length was increased up to 19 fold. Hyperplastic lesions were not seen with styrene oxide, despite the higher tumour incidence reported with this compound. We conclude that the carcinogenicity of styrene oxide to the forestomach most probably involves a mechanism in which marginal genotoxicity is combined with promotion by increased cell proliferation.
DNA binding in vivo: (6,7-\(^3\)H]ß-trenbolone (ß-TBOH) was administered p.o. and i.p. to rats. After 8 or 16 h, DNA was isolated from the livers and purified to constant specific radioactivity. Enzymatic digestion to deoxyribonucleotides and separation by HPLC revealed about 90% ofthe DNA radioactivity eluting in the form of possible TBOH-nucleotide adducts. The extent of this genotoxicity, expressed in units of the Covalent Binding Index, CBI = (~mol TBOH bound per mol nucleotide)/(mmol TBOH administered per kg body weight) spanned from 8 t~ 17, i. e. was in the range found with weak genotoxic carcmogens. Ames test: low doses of ß-TBOH increased the number of revertants in Salmonella strain TAl 00 reproducibly and m a dose-dependent manner. The mutagenic potency was 0.2 revertants per nmol after preincubation of the bacteria (20 min at 37° C) with doses between 30 and 60 \(\mu\)g per plate (47 and 94 \(\mu\)g/ml preincubation mixture). Above this dose, the number of revertants decreased to control values, accompanied by a reduction in survival. The addition of rat liver S9 inhibited the mutagenicity. DNA binding in vitro: calf thymus DNA was incubated with tritiated ß-TBOH with and without rat liver S9 Highest DNA radioactivities were determined in the absence of the "activation" system. Addition of inactive S9 (without cofactors) reduced the DNA binding by a factor of up to 20. Intermediate results were found with active S9. DNA binding in Salmonella: ß-TBOH was irreversibly bound to DNA isolated from S. typhimurium TA100 after incubation of bacteria with [\(^3\)H]ß-TBOH. Conclusions: Covalent DNA binding appears to be the mechanism of an activation-independent ("direct") mutagenicity of TBOH which is not easily detected because of the bactericidal activity. The genotoxicity risk arising from exposure of humans to trenbolone residues in meat was estimated using the in vivo data and compared to that from the exposure to unavoidable genotoxins aflatoxin B1 and dimethylnitrosamine. It ts concluded that trenbolone residues represent only a low genotoxic risk.
The thermodynainic parameters ΔH0, ΔG0 and ΔS0 - and thereby the equilibrium constants - for the complexation of the carrier antibiotics nigericin and monensin with sodium and potassium ions in methanol at 25°C have been determined by microcalorimetry. Tbc results are discussed in terms of the nature of the interaction between ligands and cations.
[\(^{14}\)C] Aflatoxin B\(_1\) (AFB\(_1\)) was isolated from cultures of Aspergillus parasiticus grown on [1-\(^{114}\)C] sodium acetate. Covalent binding of AFB1 to liver DNA of rat and mouse was determined 6-8 h afteroral administration. The effectiveness of covalent binding, expressedas DNA binding per dose in the units of a 'Covalent Binding Index' (CBI), (\(\mu\)mol aflatoxin/mol DNA nucleotides)/(mmol aflatoxin/kg animal), was found to be 10 400 for rats and 240 for mice. These CBI partly explain the different susceptibility of the two species for the incidence of hepatic tumors. The corresponding values for pig liver DN A, 24 and 48 h after oral administration, were found to be as high as 19 100 and 13 300. DNA-binding has not so far been reported for this species although it could represent an appropriate animal model for studies where a human-like gastrointestinal tract physiology is desirable. Aflatoxin M \(_1\) ( AFM\(_1\)) is a metabolite found in the milk of cows that have been fed AFB\(_1\)-contaminated diet. [\(^{14}\)C] AFM\(_1\) was also found to be produced by cultures of A. parasiticus giving a yield of about 0.3% of the total aflatoxins. A test for covalent binding to rat liver DN A revealed a CBI of 2100 shoWing that AFM\(_1\) must also be regarded as a strong hepatocarcinogen. It is concluded that AFB\(_1\) contaminations should be avoided in dairy feed.
Chemieals that induce cancer in an intact organism are called carcinogens. This term does not differentiale between their various modes of action. In this review, Werner Lutz and Peter Maier make a mechanistic distinction between carcinogens that alter the genetic information and carcinogens that interfere with epigenetic processes. They considercardnogenesis tobe an ongoing, part1y unavoidable process which is based on a succession of mutations, most likely in stem cells, leading to autonomaus cellular growth regulation. Chemical carcinogens either induce such changes through mutations (genotoxic carcinogens) or they aceeierate the accumulation of critica1 spontaneaus mut11tions (epigenetic carcinogens). Examples are given for both classes of carcinogens, and for the processes that act at genoto:tic/nuclear 11nd epigenetic/mitotic Ievels.
Rtgulatory aclio11s Iaken to reduu tht risk of harmfultffects of exposure to chemieals ofltn arenot commensurDtt with the toxicologicDf risk SJsstS&ment. A numbtr of factors relating to psychology, sociology, economics Dntl politics rather than science and medicine afftct tht final decision. Wemer Lutz and colleagues illustratt the situation using tht feuktmia-indudng chtmiCJJI benzene as an examplt.
In the inhalation system described an animal can be kept in the same atmosphere of a 2-liter desiccator for up to 24 h. The expired carbon dioxide is adsorbed with soda lime and the resulting reduced pressure is balanced by a supply of oxygen also used for the inflow of the chemical to be investigated. Urine and faeces can be collected ~eparately and the system allows a periodical control of the concentration of the chemical by sampling the air with needle and syringe.
The binding of tritiated benzo(a)pyrene (BP) to liver DNA of 25 adult male rats (SIV 50) has been determined 50 h after a single intraperitoneal injection of doses between 40 ug/kg and 4; mg/kg. The dose-response relations~ ip is linear up to i mg/kg, shows a sigmoid step towards 2 mg/kg and a shallow linear. slope above that value. TlJe 0 bserved bin ding ranges from 1.7 to 180 nmoles BP per mole DNA phosphate. The non-linearity between 1 and 2 mg/kg could be explained 0):1 the basis of an induction of metabolizing enzymes. A pure1y mathematical extrapolation of therumour incidence from a carcinogenic dose (1 x 40mg/kg for a 20% hepatoma incidence in newborn mice) to human exposure levels (aboilt 0.1 ug/kg per day) would never have followed a step like the on~ found in our experiments. Our dose-effect study therefore shows how carcinogenitity data could be extrapolated in a biologically founded way to low doses.
The determination of a covalent binding of radioactive chemieals to DNA in intact mammalian organisms is proposedas a short-term test for carcinogenicity. The effectiveness of covalent binding to rat liver DNA correlates well with the hepatocarcinogenicity known from long-term bioassays. The binding indices range over more than five orders of rriagnitude between the strongest hepatocarcinogen aflatoxin B 1 and the limit of detection of a binding with 100 f-LCi 14C-labelled chemical. The order of magnitude of binding is therefore a surprisingly good quantitative measure for carcinogenicity. The pattern of DNA binding sites is important especially for small alkylating agents where the determination of total binding might indicate a higher carcinogenic potency than is actually observed.
The intake of known dietary carclnogens was compiled and the cancer risk was estlmated on the basis of carcinogenic potencies in animals as derived from the Carcinogenic Potency Database by Gold and co-workers. The total cancer risk was compared with the number of cancer cases attributed by epidemiologists to dietary factors (one-third of all cancer cases, i.e. -80 000 per one million Jives). Except for alcohol, the known dietary carcinogens could not account for more than a few bundred cancer cases. Tbis was seen both with tbe DNA-reactive carcinogens (beterocyclic aromatic amines, polycyclic aromatic hydrocarbons, N-nitroso compounds, estragole, aflatoxin B., ethyl carbamate, to name the most important factors) as wen as with those carclnogens wbich have not been shown to react with DNA (e.g. caffelc acid and the carcinogeruc metals arsenic and cadmium). Residues and contaminants turned out to be negligible. Among the various pmsibilities to explain the discrepancy we investigated the roJe of ovemutritlon. Dietary restriction in animals is weil known for its strong reducing effect on spontaneous tumor formation. These data can be used to derive a carcinogenic potency for excess macronutrients: tbe tumor incidence seen with the restrlcted animals is taken as a control value and the increased tumor incidence in the animals fed ad libitum is attributed to the additional feed iotake. For excess standard diet in rats, a carcinogenic potency TD50 of 16 glkg/day was deduced from a recent study. Ovemutrition in Switzerland, estimated to be 5.5 kcallkg/day, was converted to excess food (1.9 g/kg/day) and tbe cancer incidence was calculated. The result, 60 000 cancer cases per one million Jives, is provocatively close to the number of cases not explained by the known dietary chemical carcinogens. Mechanistic studies will be required to test our hypothesis and investigate the role of different types of macronutrients in ovemutrition.
Known mutagens and carcinogens in the dict were compiled and the risk of cancer was estimated on the basis of average exposure Ievels in Switzerland and carcinogenic potencies from rodent bioassays. The analysis showed that, except for a1cohol, the sum of all known dietary carcinogens could only explain a few percent of the cancer deaths attributed by epidemiologists to dietary factors. The discrepancy was explained by a "carcinogenicity" of excess macronutrients. This hypothesis was based on an evaluation of dietary restriction experiments in rats and mice, where a dramatic reducing effect on spontaneaus tumour formation was seen. From these experiments, a "carcinogenic potency" was deduced for food in excess (TD50 approximately 16 g/kg per day). Ovemutrition in Switzerland was converted into excess food intake and the cancer risk estimated on the basis ofthe TD50 value. The resulting risk of60,000 cases per one million lives wou1d aJlow to explain by overnutrition almost all "diet-related" cancer deaths in humans.
Wlth radioactive compound of high specific activity, the binding of carcinogene to DNA can be measured wlth doses that are ineffective ln long-term studies. The binding of tritiated benzo(a )pyrene to liver DNA of adult male rats has been determined 50 hr after a singie l.p. injection of doses between 40 1'9/kg and 4 mg/kg. The doseresponse relationship is linear up to 1 mg/kg, shows a step towards 2 mg/kg, and gives a shallow linear slope above that value. The observed binding ranges from 1.7 to 180 nmoles benzo(a)pyrene per mole DNA phosphate. The nonlinearity could be due to an induction of metabolizing enzymes. The microsomal aryl hydrocarbon hydroxylase activity increases significantly 24 hr after a single dose of 4 mg/kg and 48 hr after doses of 2 and 4 mg/kg, but no induction Ia found with 1 mg/kg. The binding from an equimolar dose is 35 times lower than the one found on mouse skin DNA and 300 times lower than that of N,Ndlmethylnitrosamine in rat liver. A good correlatlon exiats to the respective tumor formation in long-term studles.