Refine
Has Fulltext
- yes (159)
Is part of the Bibliography
- yes (159)
Year of publication
- 1990 (159) (remove)
Document Type
- Journal article (111)
- Book article / Book chapter (21)
- Book (9)
- Conference Proceeding (9)
- Review (7)
- Jahresbericht (1)
- Report (1)
Keywords
- Toxikologie (11)
- Infektionsbiologie (9)
- Anorganische Chemie (8)
- Organische Chemie (8)
- Virologie (6)
- Kind (5)
- Aufsatzsammlung (4)
- Neurobiologie (4)
- Physiologische Chemie (4)
- Psychologie (4)
- Begabung (3)
- Biochemie (3)
- Chemie (3)
- Chirurgie (3)
- Erziehung (3)
- HIV (3)
- Immunologie (3)
- Wissen (3)
- Autoradiography (2)
- Bibliographie (2)
- Entwicklung (2)
- Erwachsener (2)
- Gedächtnis (2)
- Gedächtnisleistung (2)
- Geographie (2)
- Kognitive Entwicklung (2)
- Muscarinic receptor subtypes (2)
- Muscarinic receptors (2)
- Neurophysiologie (2)
- Semitistik (2)
- Strategie (2)
- 1 (1)
- 3 (1)
- 4-0xadiazin-6-ones (1)
- 6-Thiatricyclo[3.2.1.o 2.7 ]oct-3-ene 6 (1)
- 6-dioxide (1)
- 8-Hydroxy-deoxyguanosine (1)
- Adenosin (1)
- Adenosinrezeptor (1)
- Algerien (1)
- Alkohol (1)
- Alkoholkonsum (1)
- Alkylation (1)
- Alter (1)
- Alter Orient (1)
- Amazon Molly (1)
- Ameise (1)
- Ameisen (1)
- Amino acids (1)
- Angewandte Psychologie / Zeitschrift / Experimentelle Psychologie (1)
- Annual Report (1)
- Antarktis (1)
- Axonal degeneration (1)
- Barbaralane derivatives (1)
- Baum (1)
- Beifahrer (1)
- Bericht (1)
- Bibliographie 1962-1989 (1)
- Bilma <Region> (1)
- Biologie (1)
- Boğazkale (1)
- Carbachol-induced drinking (1)
- Carcinogen risk Individual susceptibili (1)
- Choline deficiency (1)
- Cyclopropanetetracarbonitrile derivatives (1)
- DDR (1)
- DNA (1)
- DNA binding (1)
- DNA damage (1)
- Deutsch / Wörterbuch / Mittelhochdeutsch (1)
- Deutsches Sprachgebiet (1)
- Diels-Alder reactions (1)
- Einfluss (1)
- Electron transfer (1)
- Electrophiles (1)
- Endogenous genotoxicity (1)
- Enol Iactones (1)
- Entwicklungspsychologie (1)
- Erbendorf (1)
- Escherichia coli (1)
- Etrusker (1)
- Extremwert (1)
- Fahrerverhalten (1)
- Fahrverhalten (1)
- Familientherapie (1)
- Frau (1)
- Freiburg (1)
- Genetic instability (1)
- Genome analysis (1)
- Genotoxicity (1)
- Geschichte 1962-1989 (1)
- Glucagon (1)
- Griechenland <Altertum> / Beleuchtung / Architektur (1)
- Guinea-pig uterus (1)
- HTLV-I (1)
- Herpesviren (1)
- Herzneurose (1)
- Hexahydro-procyclidine (1)
- Holozän (1)
- Homo Diels-Alder reactions (1)
- Hypothalamus (1)
- Immunohistochemistry; Immunogold-silver staining; FITC- anti-FITC system; Leucocyte subpopulations; Two-color staining (1)
- In-vivo dia lysis (1)
- Industriegesellschaft (1)
- Insulin (1)
- Intelligenzleistung (1)
- Islets of Langerhans (rat) (1)
- Jahresbericht (1)
- Karst (1)
- Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland (1)
- Kraftfahrer (1)
- Krebs <Medizin> (1)
- Kunst (1)
- Künstliche Intelligenz (1)
- Landeskunde (1)
- Legionella ssp. (1)
- Lernerfolg (1)
- Lesenlernen (1)
- M4 receptors (1)
- Magnesium (1)
- Mastzelle (1)
- Metagedächtnis (1)
- Methoctramine (1)
- Microinjection (1)
- Miltenberg (1)
- Mittelhochdeutsch / Wörterbuch (1)
- Montessori (1)
- Moran (1)
- Multiple sclerosis (1)
- Mundart (1)
- Muscarinic M1 receptors; Muscarinic M2 receptors (1)
- Muscarinic receptor antagonists (1)
- Muscarinie M2 receptors (1)
- Musearinic M4 receptors (1)
- Musearlnie M1 (1)
- Natur (1)
- Nektarium (1)
- Nervenregeneration ; Periphere Nervenverletzung ; Neuromuskuläre Krankheit ; Axonverletzung ; Entmarkung (1)
- Neuropeptides (1)
- Niere (1)
- Niger (1)
- Niger <Ost> (1)
- Nitrosation (1)
- Nordvictorialand (1)
- Orthogonal field attenuation gel electrophoresis (1)
- Oxygen radical (1)
- P-fimbriae (1)
- Pharmacokinetics (1)
- Pharmakologie (1)
- Photochemistry (1)
- Physiologische Psychologie (1)
- Pirenzepine (1)
- Pleistozän (1)
- Po (1)
- Polymerase chain reaction (1)
- Promillegrenze (1)
- Protein-Tyrosin-Kinasen (1)
- Pyrrinol (1)
- Pädagogische Psychologie (1)
- Radical-ion pair (1)
- Radicals (1)
- Rangstatistik (1)
- Rat (1)
- Rat hippocampus (1)
- Rat liver peroxisome (1)
- Regenwald (1)
- Report (1)
- Romanistik (1)
- S fimbrial adhesin (Sfa) (1)
- Schreibenlernen (1)
- Schulleistung (1)
- Schwertkärpfling (1)
- Selbsteinschätzung (1)
- Sila-drug (1)
- Sila-hexocyclium (1)
- Silver degeneration staining (1)
- Skorpion (1)
- Sozialkundeunterricht (1)
- Soziologie (1)
- Spontaneous tumours (1)
- Statistik (1)
- Synaptische Vesikel (1)
- Synaptophysin (1)
- Systemische Therapie (1)
- TRH (1)
- Textverarbeitung <Psycholinguistik> (1)
- Thymidine glycol (1)
- Trunkenheit im Verkehr (1)
- Umwelterziehung (1)
- University Library (1)
- Universitätsbibliothek (1)
- Urazoles (1)
- Verkehrssicherheit (1)
- Vohenstrauß (1)
- Volkskunde (1)
- Vorschulkind (1)
- William L. (1)
- Wilson Terrane (1)
- Wuerzburg (1)
- Wurzburg (1)
- Würzburg (1)
- Xiphophorus (1)
- Zink (1)
- Zoologie (1)
- [3H]-Hexahydro-siladifenidol (1)
- [3H][3Me-His2]-TRH (1)
- acid secretion (1)
- alpha (1)
- animals (1)
- bicyclic (1)
- extraintestinal E. coli (1)
- gastric acid/secretion (1)
- gastric/secretion parietal cells (1)
- gene regulation (1)
- genetic organization (1)
- genomic deletions (1)
- glandular M3 receptor (1)
- hemolysin (1)
- hexahydrosiladifenidol (1)
- human gastric mucosa (1)
- immunoglobulin superfamily (1)
- muscarinic receptor subtype (1)
- muscarinic receptors (1)
- muscarinic/drug effects receptors (1)
- muscarinic/physiology receptors (1)
- nucleotide sequence (1)
- parasympatholytics (1)
- parasympatholytics/pharmacology (1)
- peripheral nervous system (1)
- photochemical (1)
- piperazines (1)
- piperazines/pharmacology (1)
- piperidines (1)
- piperidines/pharmacology (1)
- polycyclic (1)
- radioligand assay (1)
- rats (1)
- receptors (1)
- silahexocyclium (1)
- stomach (1)
- vaccinia virus (1)
- virulence modulation (1)
- y-Oxoketenes (1)
- Älterer Verkehrsteilnehmer (1)
- ß-Lactones (1)
- ß-unsaturated (1)
Institute
- Theodor-Boveri-Institut für Biowissenschaften (25)
- Institut für Psychologie (bis Sept. 2007) (19)
- Institut für Pharmakologie und Toxikologie (15)
- Institut für Anorganische Chemie (14)
- Institut für Molekulare Infektionsbiologie (12)
- Institut für Organische Chemie (11)
- Institut für Virologie und Immunbiologie (9)
- Institut für Geographie (6)
- Institut für Psychologie (6)
- Institut für Politische Wissenschaft (5)
Synaptophysin: a substrate for the protein tyrosine kinase pp60c-src in intact synaptic vesicles
(1990)
Expression of pp60 c-src, the first well defined proto-oncogene product, is developmentally regulated and tissue-specific, with neuronal tissues displaying high amounts of the c-src encoded pp60 c-src kinase activity. In the central nervous system pp60 s-src is preferentially expressed in regions characterized by a high content of grey matter and elevated density of nerve terminals. In this study we show for the first time a direct interaction between pp60 c-src and synaptophysin as a physiological target protein in neurons by demonstrating that endogenous pp60 c-src is able to phosphorylate synaptophysin (p38). p38 is a major constituent of the synaptic vesicle membrane protein and is thought to play a key role in the exocytosis of small synaptic vesicles and possibly small clear vesicles in neuroendocrine cells.
Genome analysis of Legionella spp. by orthogonal field alternation gel electrophoresis (OFAGE)
(1990)
Various Legionella isolates from different sources and origins were analysed by orthogonal field alternation gel electrophoresis of Not I cleaved genomic DNA. The genome of L pneumophila Philadelphia I, the original isolate of the epidemics in 1976, exhibits only five Not I fragments. Two virulent derivatives. derived from L pneumophila Philadelphia I. which were obtained by prolonged passage on artificial cuhure media, did not differ from their isogenic virulent strain according the Not I fragment pattern. By summing the lengths of the Notl fragments, the genome size of L. pneumophila Philadelphia I was calculated as approximately 3.9 Mb. Environmental L pneumophila strains exhibited different Not I pattems, as did Legionella strains not belongi'ng to the species pneumophila. The usefulness of DNA long range mapping of Legionella ssp. with Notl for epidemiology and evaluation of their evolutionary rela· tionships is discussed.
We have previously shown that during an infection with Leishmania major, susceptible BALB/c mice, as opposed to mice of a resistant strain (C57BLl6), are primed by lipopolysaccharide for the production of high levels of tumor necrosis factor-\(\alpha\) (TNF-\(\alpha\)) which is known to be a potent maerophage M\(\Phi\) stimulator in other parasitic diseases. In the present study we investigated whether TNF-\(\alpha\) activates M\(\Phi\) for killing of L. major parasites. In the absence of interferon-y (IFN-\(\gamma\)) or lipopolysaccharide, TNF-\(\alpha\) (0.025-25000 U/ml) failed to activate peritoneal exudate M\(\Phi\) from BALB/c mice for killling of L. major amastigotes. In the presence of suboptimal doses of IFN-\(\gamma\) (5 or 10 Vlml), however, TNF-\(\alpha\) mediated a rapid elimination of intracellular parasites, which was highly significant compared to IFN-\(\gamma\) alone. Tbe combination of TNF with interleukin 4, in contrast, was inactive in this respect and allowed survival of intracellular parasites. From these data we conelude that the presence of IFN-\(\gamma\) is crucial for TNF-\(\alpha\)-mediated killing of L. major parasites by M\(\Phi\). Disease progression in susceptible mice therefore seems to be a consequence of a deficiency of IFN-\(\gamma\) and a predominance of interleukin 4 rather than the result of an excess amount of TNF-\(\alpha\).
Linear dose-response relationship for DNA adducts in rat liver from chronic exposure to aflatoxin B1
(1990)
Male F-344 rats were given eH]aßatoxin B1 (AFB1) in the drinking water at three exposure Ievels (0.02, 0.6, 20 J,Lgll, resulting in average dose Ievels of 2.2, 73, 2110 nglkg per day). After 4, 6 and 8 weeks, DNA was ~ted frorn the livers and analyzed for aßatoxin-DNA adducts. Tbe Ievel of DNA adducts did not increase significantly after 4 weeks, indicating that a steady-state for adduct formation and removal had nearly been reached. At 8 weeks, the adduct Ievels were 0.91, 32 and 850 nucleotide-aßatoxin adducts per to' nucleotides, i.e. clearly proportional to the dose. At the high dose Ievel, a near SO% tumor incidence would be expected in a 2-year bioassay with F -344 rats while the low dose used is within the range of estlmated human dietary exposures to aßatoxin in W estem countries. The proportionality seen between exposure and steady-state DNA adduct Ievel is discussed with respect to a linear extrapolation of the tumor risk to low dose.
No abstract available
No abstract available
No abstract available
Monoclonal antlbodies (MAbs) directed against Xiphophorus melanoma cells were deve(oped and tested by lndirect immunofluorescence and Immunoperoxidase staining for reactivity with a panel of I 5 allogeneic tissues and 12 allogeneic cell llnes. The reactivity of such MAbs was restricted to melanoma cells from tumor biopsies and melanoma-derived cell lines. ln addition, all embryonie cells of all histiotypes from developmental stages later than mld·organogenesis and from corresponding short term in vitro cultures reacted with these MAbs. ln contrast, normal tissues and organs from adult fish dlsplayed no reactivity, thus implying that the melanoma-associated antigens detected by the MAbs described are oncofetal antigens.
No abstract available
Novel pharmacological profile of muscarinic receptors mediating contraction of the guinea-pig uterus
(1990)
The present study was designed to further characterize the muscarinic receptors mediating contraction of the guinea-pig uterus. The affinities of various selective muscarinic antagonists were determined and compared with those obtained at M\(_1\) (rabbit vas deferens), M\(_2\) (guinea-pig atria) and M\(_3\) receptors (guinea-pig ileum). The contractile responses of uterine smooth muscle from immature guinea-pigs to carbachol (pD\(_2\) = 5.73) were competitively antagonized by pirenzepine (pA\(_2\) = 7.04), AF-DX 116 (11-[[2-[(diethylamino)methyl]-1-piperidinyl] acetyl]- 5,11-dihydro-6H -pyrido[2,3-b][1 ,4]benzo. diazepin-6-one) (pA\(_2\) = 6.96), himbacine (pA\(_2\) = 7.92), methoctramine (pA\(_2\) = 7.52), 4-DAMP (4-diphenylacetoxy- N-methylpiperidine methiodide) (pA\(_2\) = 8.87) and sila-hexocyclium (pA\(_2\) = 8.81). A comparison of affinity values indicates that the muscarinic receptors present in guinea-pig uterus display a novel pharmacological profile which is not consistent with the presence of either an M\(_1\), M\(_2\) or M\(_3\) receptor. The affinities determined for the different antagonists rather showed a close similarity to those obtained at muscarinic receptors present in rat striatum and NG108-15 cells which are considered pharmacological equivalents (M\(_4\) receptors) of the m4 gene product. We thus hypothesize that the guinea-pig isolated uterus preparation may serve as a simple functional assay system to study the pharmacology of M\(_4\) receptors.
No abstract available
No abstract available
Verhaltensmedizin
(1990)
No abstract available
Introduction Although symptomatic therapy is available for Parkinson's disease, patients and relatives are faced with continuous severe psychological problems. These psychological problems include: 1. lack of emotional expression, 2. bradephrenia, 3. depression, 4. lack of motivation,S. social anxiety, 6. stress induced increase of symptoms. The first four of these may be at least in part due to the dopamine deficiency. However, even as part of the primary symptoms they have social and communicative impact for patients and relatives. Social anxiety and stress induced increase of symptoms on the other hand clearly result from an interaction of somatic and psychological factors. Social anxiety mainly develops in Parkinson I s disease as an indirect consequence of the motor symptoms. Patients are afraid of being negatively evaluated in the public, of receiving negative comments etc. Thus r social withdrawal increases and the improvement of neurological symptoms following drug treatment may not be fully exploited on the psychosocial level. Stress induced increase of motor symptoms is a commonly observed phenomenon in Parkinson's disease. Even minor stressors, mainly social in nature, can have extreme effects and may elicit or increase tremor or rigidity. A patient can be well in one moment, but unable to move in the next when being aware that he has to leave the house in an hour. Given this situation, patients and relatives have to develop strategies fo~ an emotional balance in the presence of a continuous confrontation with the direct and indirect consequences of the disease. A precondition for developing new psychologically based strategies is an optimwn medical treatment. The integrated approach for neurological and psychological support has the following goals: 1. improving medical treatment for the individual patient, 2. improving psychological coping and psychosocial adaptation for patients and relatives, and 3. evaluating and improving medical and psychological therapy. CONCLUSION Psychological intervention can provide considerable help for a substantial part of Parkinson patients. The main target is coping with stressful social situations. Relaxation and cognitive restructuring together with situational behavioral analysis and training of social skills specifically adapted to the disease are" the main strategies. Various problems remain open at the moment, like the maintenance of motivation which is especially critical for Parkinson patients. Parkins on 's disease is a neurological disease with a known pathological substrate and a therapy which is effective at least for several years on a symptomatic level. The symptoms are tightly connected with psychological emotional and cognitive processes. Moreover, patients and relatives have to cope with symptoms which strongly influence social interaction. And they have to cope together with this situation over a period of ten or twenty years. Thus not only for the patient but also for the health of the relatives, psychological aid is urgently needed. We suggest to integrate psychological approach into the neurological diagnosis and treatment.
Large-scale multireference configuration interaction calculations in a double·t·type AO basis including polarization functions are carried out for the potential surface of the ClC\(_2\)H\(_4\9 system. The charge distribution for various extreme points of the surface is discussed. The absolute minimum is found for an asymmetric ClC2H4 structure. The symmetrical bridged nuclear conformation is also found to be stable with respect to dissociation into Cl + C\(_2\)H\(_4\)• The activation energy for rotation about the C-C axis is calculated tobe around 18 kJ/mol, which is comparable tothat for the 1,2 migration {around 26 kJ/mol). The stereochemistry is governed by the fact that addition of CI to C\(_2\)H\(_4\) (or dissociation) is a two-step reaction proceeding through a symmetrica1 intermediate. The direct addition pathway possesses a small barrier of about 8 kJ jmol.
Neoplastic cell transfonnation induced by estrogens and some other carcinogen& such as benzene appears to involve the induction of mitotic aneuploidy rather than DNA damage and point mutations. As metabolic activation may also play an important roJe in the mechanism of carcinogenesis of these nongenotoxic compounds, we have studied the Interaction of reactive quinone metabolites of various estrogens and of benzene with the major microtubular protein, tubulin, in a cell-free system. Covalent binding of the radioactively labeled metabolites to the a- and 13-subunit of tubulin was found to depend on the structure of the metabolite. When the adducted tubulins were tested in vitro for their ability to polymerize to microtubules, Inhibition of microtubule assembly was obsened in every case, although to varying extents. It is proposed that the fonnation of covalent tubulin adducts may impair the formation of mitotic spindies and thus contribute to chromosomal nondisjunction and aneuploidy induction.
1 Tbc affinities of the (R)- and (S)-enantiomers of hexahydro-difenidol (1) and its acetylenie analogues hexbutinol (2), hexbutinol methiodide (3) and p-fluoro-hexbutinol (4) (stereochemieal purity > 99.8%) for musearlnie receptors in rabbit vas deferens (M1), guinea-pig atria (M2) and guinea-pig ileum (M3) were measured by dose-ratio experiments. 2 The (R)-enantiomers consistently showed higher aßinities than the (S)-isomers. The stereosclectivity ratios [(R)/(S)] wcrc greatest with thc enantiomers of 1 (vas deferens: 550; ilcum: 191; atria: 17) and least with thosc ofthc p-Fluoro-analogue 4 (vas defercns: 34; ileum: 8.5; atria: 1.7). 3 The enantiomerie potency ratios for compounds 1-4 were highest in rabbit vas deferens, intermediate in guinea-pig ileum and much less in guinea-pig atria. Thus, these ratios may serve as a predietor of muscarinic receptor subtype identity. 4 (S)-p-Fluoro-hexbutinol [(S)-4] showed a novel receptor selectivity profile with preference for M\(_3\) receptors: M\(_3\) > M\(_2\) \(\geq\) M\(_1\)• 5 These results do not conform to Pfeiffer's rule that aetivity differences between enantiomers are greater with more potent compounds.
No abstract available
No abstract available
C. borneensis (Myrmicinae) lives in dose association with several myrmecophytic species of the South East Asian pioneer tree genus Macaranga (Euphorbiaceae). The ants are adapted to the plants so dosely that they do not survive away from it. The only food they utilize is provided as food bodies by the plant and honeydew from specific scale insects kept inside the hollow internodes. The anatomy of the digestive tract is also adapted to life on the host plant: the crop is very sm all and can store only minute food quantities. C. borneensis exdusively colonizes certain Macaranga species. Queens as weIl as workers are able to recognize their host plant species, probably by chemical cues. Colony founding queens swarm throughout the year, mostly during darkness. There is strong competition among queens for host plants. Queens do not carry scale insects on their nuptial flight. Worker ants are active day and night. Most of them patrol and collect food bodies on the younger parts of the host plant. An important characteristic is their deaning behaviour, which results in removal of aIl foreign objects. Even though they are rather smalI, workers respond very aggressively to certain kinds of disturbance of the host plant. The ants attack most phytophagous insects and are especially effective in killing and removing smalI, softbodied herbivores (e.g. caterpillars). They do not possess a functional sting, but apply defensive secretion and-once biting an intruder-will not let go. Their effective alarm system results in a mass attack, which provides adequate defence for the colony and the host plant. A comparison with another Crematogaster species further illustrated the special adaptations of C. borneensis to its host plant.
No abstract available
ln order to construct fish specific expression vectors for studies on gene regulation in vitro and in vivo a variety of heterologous enhancers and promoters from mammals and from viruses of higher vertebrate cells were tested for expression of the bacterial chloramphenicol acetyl transferase reporter gene in three teleost fish cell lines. Several viral enhancers were found to be constitutively active at high Ieveis. The human metallothionein promoter showed inducible expression in the presence of heavy metal Ions. A fish sequence was isolated that can be used as a homologous constitutively active promoter for expression of foreign genes. Using the human growth hormone gene with an active promoter in fish cells for transient expression insufficient splicing and Iack of translation were observed, pointing to limitations in the use of heterologous genes in gene transfer experiments. On the contrary, some heterologous promoters and enhancers functioned in fish c as weil as in their cell type of origin, indicating t at corresponding transcription factors are sufficient conserved between fish and human over a period of 900 million years of Independent evolution.
Study of the hyperfine coupling constants of the moleculs NH<sub>2</sub>, NHD and ND<sub>2</sub>
(1990)
In the present paper we c:alculate tbe magnetic hyperfine couplina constants (hfcc) ai.ID and A11 of the ground states of the isotopes NH2, NHD and ND2 using truncated MR..CI methods. Differences from other theoretical methocls and shortoominp of the truncated Cl approach in calculating tlj10 are studied. Polarization effects wbich detennirae ailo. as weU as a simple model to describe the dipolar hfcc's, are discussed. All results are in. excellent aareement with experimental data. lt is shown that ab initio methods are able to obtain reliable values for otf-diaaonal values of A41 which are difficult to measure experimentaDy.
The human gene encoding the myogenic determination factor myf3 (mouse MyoD1) has been mapped to the short arm of chromosome 11. Analysis of several somatic cell hybrids containing various derivatives with deletions or translocations revealed that the human MyoD (MYF3) gene is not associated with the WAGR locus at chromosomal band 11pl3 nor with the loss of the heterozygosity region at 11p15.5 related to the Beckwith-Wiedemann syndrome. Subregional mapping by in situ hybridization with an myf3 specific probe shows that the gene resides at the chromosomal band llp14, possibly at llp14.3.
We have developed a reliable and sensitive immunohistochemical staining technique which allows the simultaneous demonstration of two different antigens expressed in or on the same cell (referred to as mixed labeling), together with the evaluation of the general histopathological appearance of the tissue. The staining procedure combines a three-step (streptavidin-biotin) immunogold-silver staining (IGSS) with a three-step immunoenzymatic labeling. For this purpose, we investigated the compatibility ofIGSS with various substrates of peroxidase or alkaline phosphatase (AP). Highly reliable and discernible mixed labeling was achieved only after iniriallabeling with IGSS followed by AP labeling using the substrates naphthol AS-MX phosphate/Fast Blue or naphthol AS-HI phosphate/New Fuchsin, respectively. To ensure utmost specificity, we applied FlTC-conjugated mouse monoclonal antibodies and rabbit anti-FlTC immunoglobulins visualized by AP-labeled immunoglobulins and the respective substrate in a final step. This novel approach provides an excellent means for demonstration of immunocompetent cells and unequivocal determination of the percentage of specific cell subsets in infiltrated tissue. The advantages of this method, as compared with double immunofluorescence or double immunoenzymatic labeling, were investigated and are discussed. (J Histochem Cytochem 38:307-313, 1990)
Active neuropeptide Y receptors were solubilized from rabbit kidney membranes using the zwitterionic detergent 3-[ (3-cholamidopropy l)dimethylammonio ]- 1-propanesulfonic acid (CHAPS). In membrane fragmentsandsoluble extracts neuropeptide Y bindingwas time dependent, saturable, reversible, and of high affinity. Scatchard analysis of equilibrium binding data indicated a single class of binding sites with respective Kn and Bmax values of 0.09 nM and 530 fmol/mg of protein for the membrane-bound receptors and 0.10 nM and 1585 fmol/mg of protein for the soluble receptors. Neuropeptide Y bindingwas specifically inhibited by the nonhydrolyzable GTP analog guanosine 5' -0- (3-thiotripbosphate) in a concentration-dependent manner, with IC\(_{50}\) values of 28 and 0.14 \(\mu\)M for membrane- bound and soluble receptors, respectively, suggesting that neuropeptide Y receptors are functionally coupled to GTP-binding regulatory proteins. CrossHoking studies were performed with the heterobifunctional N-hydroxysuccinimidyl-4-azidobenzoate and the monofunctional neuropeptide Y derivative, azidobenzoyl and led to the identification of a 100 kDa peptide that should represent the covalently labeled neuropeptide Y receptor.
Im Nordosten der Republik Niger sind Karstformen in Sandsteinen, Silcretes, Eisenkrusten und im Kristallin weit verbreitet. Aufgrund geomorphologischer Untersuchungen und mikromorphologischer Analysen läßt sich eine echte Verkarstung im Sinne lösungsbedingter Reliefformung nachweisen. Untersuchungen an Dünnschliffen und rasterelektronenmikroskopische Analysen von Quarzkomoberflächen zeigen extrem starke Kornkorrosion in den äußeren Probenbereichen (Wandungen von Karstformen) und allgemein starke Spuren von Kieselsäuremobilisierung. Die Ausfällung von Kieselsäure auf den Quarzkörnern kann bis zur Neukristallisation von Quarz reichen (Djado, Stufe von Bilma) oder nur als amorpher Überzug ausgebildet sein (Massive von Tennit und Koutous). Die Gesamtheit der Befunde deutet auf eine Hauptphase der Verkarstung im frühen Tertiär hin, die von weiteren Lösungsphasen im jüngeren Tertiär und wahrscheinlich auch im Quartär gefolgt wird. Die jeweils über weite Räume ähnlichen Befunde lassen eine Abhängigkeit des Verkarstungsgeschehens von den paläoklimatischen Bedingungen vermuten; vor allem durch die Ausbildung eines unterirdischen Entwässernngs- und Hohlraumsystems sind enge Wechselbeziehungen zwischen Karstformenschatz und der Entwicklung der übrigen Reliefelemente gegeben.
Vorwort (Das Kind (1990) 8)
(1990)
No abstract available
Vorwort (Das Kind (1990) 7)
(1990)
No abstract available
Montessori in der DDR?
(1990)
No abstract available
Male rats were treated for 2 months with 1000 ppm nafenopin in the diet or for 4 or 7 days with a choline-devoid low-methionine diet. DNA was isolated from the livers and analyzed for the presence of cis-thymidine glycol-3'-phosphate (cis-dTGp) by 32P-postlabeling and for the Ievel of 8-hydroxy-deoxyguanosine (8-0H-dG) by electrochemical detection (ECD). In no DNA sample was the Ievel of cis-dTGp above the Iimit of detection of 1 modified thymidine per 106 nucleotides. With 8-0H-dG, a background Ievel of this modification of 20 8-0H-dG per 106 nucleosides was found in liver DNA of control rats, which was not affected by either treatment. It is postulated for thymidine glycol that a potential increase was below the Iimit of detection or was rapidly repaired in vivo and that the steady-state Ievel of endogenous 8-hydroxydeoxyguanosine appears not tobe influenced by the treatments chosen.
No abstract available
Kinder aus 3 Altersgruppen und Erwachsene beurteilten die verdiente Strafe für in Geschichten dargestellte Sachschäden, die aus Versehen oder aus Wut erfolgten. In den Geschichten wurde die Schadenshöhe variiert und außerdem, ob sich der Täter entschuldigte oder nicht bzw. ob der Geschädigte von einem Dritten eine Entschädigung erhielt oder nicht. Entschuldigung und Schadenshöhe hatten altersstabile Wirkungen, Entschuldigung etwa zweimal so stark wie die Schadenshöhe. Entschuldigung und Drittentschädigung hatten etwa gleichgroße Wirkungen, außer bei den Erwachsenen, bei denen die Wirkung der Drittentschädigung etwa auf die Stärke der Schadenswirkung abnahm. Der ursprüngliche Schaden war auch bei erfolgter Entschädigung, wenngleich schwächer, wirksam. Die Wirkungen der Ersatzleistung durch den Täter auf Strafurteile waren jedoch nicht völlig durch die Wirkungen von Entschuldigung und Entschädigung, erklärbar.
No abstract available
No abstract available
No abstract available
DNAs from peripheral blood mononuclear cells (PBMCs) of 21 patients with multiple sclerosis (MS), 1 patient with tropical spastic paraparesis (TSP) as well as DNAs from brain and spinal cord of 5 MS cases and 3 controls were examined for human T-cell lymphotropic virus (HTLV)-related sequences by polymerase chain reaction. The primers used were derived from the HTLV-1 gag, env and tax genes. Amplified products were separated on agarase gels, blotted onto nylon membranes and hybridized to specific radiolabelled oligonucleotides. The sensitivity of amplification and hybridization was one copy of target DNA in 10\8^5\) cellular genomes. None of the specimens was positive for HTLV-1 sequences except the TSP probe. These negative data are all the more significant because brain -material from MS patients was used in these studies. Our studies thus fail to support speculations that HTLV-I is involved in the aetiology of multiple sclerosis.
Potential energy and spectroscopic constants for the X\(^2 \sum^+ _\mu\) ground state of a;, were calculated by configuration-interaction (Cl) methods, using large basis sets with polarization and diffuse functions. From these CI wavefunctions, the isotropic (a\(_{iso}\)) and dipolar (A\(_{dip}\)) components of the hyperfine coupling constant were obtained. The effects of various s, p basis sets, polarization and diffuse functions, as well as the influence of reference configurations and configuration selection thresholds were investigated. The best values obtained are 35·31 G for a\(_{iso}\) and 29·440 for A\(_{dip}\)• tobe compared with experimental values of 37 ± 1 G and 32 ± 1 G, respectively. It is shown that the contributions to a1so of the K and L shells are opposite in sign, differing by about 4 G. Upon vibrational averaging, both a\(_{iso}\) and A\(_{dip}\) move towards smaller values as v increases. An adiabatic electron affinity of 2·46eV was obtained for CL\(_2\) , and a vertical electron detachment energy of 3·71 eV for Cl;.
Pseudopotentials and valence basis sets to be used in calculations for organometallic compounds of zinc and magnesium have been tested in calculations for the M(CH\(_3\))\(_n\) (M = Zn, Mg; n = 1,2) molecules. Valence correlation effects are treated at the SDCI and CEPA levels. The capability of a polarization potential on zinc to account for the valence shell contracting effect of core valence correlation is studied. Properties considered are geometries, force constants, Mulliken populations, ionization potentials, atomization, and binding energies. Differences in bonding between the two dimethyl compounds are discussed.
The transient yellow color observed in the cycloaddition of homobenzvalene (HB) with tetracyanoethylene (TCNE) is associated with the charge-transfer complex [HB, TCNE). The deliberate photoexcitation of [HB,TCNE) affords a mixture of charge-transfer cycloadducts (1, 2, and 3) that differs from that obtained in thermal cycloaddition. The relationship of {HB t TCNE•) radical-ion pair (as the critical reactive intermediate in charge-transfer cycloaddition) to the activation process for thermal cycloaddition is discussed.
No abstract available
No abstract available
No abstract available
The effects of guanine nucleotides on binding of 8-cyclopentyl-1,3-[\(^3\)H]dipropylxanthine [\(^3\)H]DPCPX), a highly selective A\(_1\) adenosine receptor antagonist, have been investigated in rat brain membranes and solubilized A\(_1\) receptors. GTP, which induces uncoupling of receptors from guanine nucleotide binding proteins, increased binding of [\(^3\)H]DPCPX in a concentration-dependent manner. The rank order of potency for different guanine nucleotides for increasing [\(^3\)H]DPCPX bindingwas the same as for guanine nuc1eotide-induced inhibition of agonist binding. Therefore, a role for a guanine nucleotide binding protein, e.g., G\(_i\), in the regulation of antagonist binding is suggested. This was confirmed by inactivation ofGi by N-ethylmaleimide (NEM) treatment of membranes, which resulted in an increase in [\(^3\)H]DPCPX binding similar to that seen with addition of GTP. Kinetic and equilibrium binding studies showed that the GTP- or NEM-induced increase in antagonist binding was not caused by an affinity change of A\(-1\) receptors for [\(^3\)H]DPCPX but by an increased Bmu value. Guanine nucleotides had similar effects on membrane-bound and solubilized receptors, with the effects in the solubilized system being more pronounced. In the absence of GTP, when rnost receptors are in a high-affinity state for agonists, only a few receptors are labeled by [\(^3\)H]DPCPX. It is suggested that [\(^3\)H]DPCPX binding is inhibited when receptors are coupled to G\(_i\). Therefore, uncoupling of A\(_1\) receptors from G\(_i\) by guanine nucleotides or by inactivation of G\(_i\) with NEM results in an increased antagonist binding.
Key Words: Adenosine receptors-8 -Cyclopentyl-1,3-eH]dipropylxanthine-Antagenist binding-Guanine nucleotide effects. Klotz K.-N. et al. Guanine nucleotide etfects on 8-cyclopentyl-1 ,3-eH]dipropylxanthine binding to membrane-bound and solubilized A1 adenosine receptors of rat brain. J. Neurochem. 54, 1988-1994 (1990).
No abstract available
No abstract available
Auf der Grundlage von 1.126 empirischen Befunden stellt die vorliegende Literaturstudie dar, inwieweit die Fahrtüchtigkeit von Verkehrsteilnehmern bei Blutalkoholkonzentrationen (BAK) bis 0,8 Promille beeinträchtigt wird. Es zeigt sich, daß ab 0,3 Promille BAK bereits nachweisbare Wirkungen feststellbar sind. Ab 0,5 Promille treten deutliche Beeinträchtigungen auf: Rasch wechselnde Verkehrssituationen, unvorhersehbare Ereignisse, Mehrfachanforderungen an den Fahrer oder Situationen mit agressionsauslösenden Reizen werden schlecht bewältigt. Fahranfänger, die über weniger automatisierte Handlungen verfügen und ältere Verkehrsteilnehmer mit ihren größeren Schwierigkeiten bei Kontrollprozessen sind besonders gefährdet. Die Studie kommt zu dem Schluß, daß eine Absenkung des Gefahrengrenzwertes auf 0,5 Promille BAK zu befürworten ist. Das detaillierte Gesamtergebnis sowie ein umfangreiches Verzeichnis der bearbeiteten Literatur ist als Heft 213 der Reihe Forschungsberichte der Bundesanstalt für Straßenwesen veröffentlicht.
No abstract available
No abstract available
Die Literaturstudie zum Thema "Auswirkungen geringer Alkoholmengen auf Fahrverhalten und Verkehrssicherheit• (FP 8707) wählte aus rund 100 000 geprüften Literaturangaben, nach strengen methodischen Kriterien , 1 126 empirische Befunde im Bereich unter 0,84 Promille BAK aus. Es zeigt sich , daß ab 0,3 Promille BAK nachweisbare Wirkungen des Alkohols vorhanden sind. Bis zu 0,5 Promille sind diese noch stark von den untersuchten Personen und Situationen abhängig, so daß dieser Bereich nicht maßnahmenrelevant erscheint. Bei Konzentrationen über 0 ,5 Promille hat Alkohol deutliche Wirkungen in Verkehrssituationen, die ein hohes Maß an Kontrollprozessen verlangen. Solche sind gefordert, wenn das Fahren an rasch wechselnde, unvorhersehbare Situationen angepaßt werden muß oder wenn sich mehrere Anforderungen gleichzeitig stellen . Ebenfalls deutliche Wirkungen sind in Verkehrssituationen zu erwarten. die einen sozialen Aufforderungsgehalt haben, insbesondere solche mit aggressionsauslösenden Reizen (etwa Bedrängen , Überholtwerden, Vorfahrtsfragen usw). Geringere Wirkungen zeigen sich in Standardsituationen wie Abbiegen, Überholen usw. Fast keine Wirkungen zeigen sich in nicht beanspruchenden Situationen , wo eine leichte Beeinträchtigung nicht leistungsmindernd ins Gewicht fällt oder durch eine Erhöhung der Anstrengung kompensiert werden kann. Die gleiche BAK ist umso gefährlicher, je weniger der Fahrer über automatisierte Handlungen verfügen kann, je mehr er auf Kontrollprozesse angewiesen ist. Dies ist der Fall vor allem bei wenig geübten Fahrern, regelhaft bei Fahranfängern. Aber auch älteren Verkehrsteilnehmer mit ihren größeren Schwierigkeiten bei Kontrollprozessen sind in besonderem Maße betroffen. Legt man die in§ 24a StVG für den Grenzwert von 0 ,8 ausgesprochene Wirkungsvermutung zugrunde, zeigt das Review eindeutig , daß eine BAK über 0,5 Promille in vielen Verkehrssituationen (nicht in allen ) und/oder bei zahlenmäßig großen Risikopopulationen (nicht bei allen) die Leistungen so deutlich mindert, daß von einer abstrakten Gefährdung des Straßenverkehrs auszugehen ist. Damit ist eine Absenkung des Gefahrengrenzwerts auf 0,5 Promille zu befürworten .
Previous research has shown German children to be more strategic on sort-recall memory tasks than their American age-mates, and to show fewer effort-related attributions. We conducted this study to determine if those differences are due to systematic differences in the strategy instruction and attributional beliefs of German and U.S. teachers, and to explore metacognitive instructional practices in the two countries. Teachers responded to a questionnaire that inquired about their use of strategy instructions, fostering of reflective thinking in pupils, sources of children’s learning problems, and modeling of metacognitive skills such as monitoring. The second part of the questionnaire asked about the reasons underlying children’s academic successes and failures. German teachers reported more instruction of task-specific strategies, while American teachers showed more effort-related attributions. The types of strategies instructed and types of learning problems most frequently described varied across the two countries, and also according to how many years the teachers had taught. Results were discussed regarding their implications for metacognitive developmental theory, particularly regarding culture and other environmental influences on the development of controlled processing.
Familiale Arbeitsteilung bei Studierenden mit Kleinkindern : Erste Ergebnisse einer Zeitbudgetstudie
(1990)
Gerade bei jungen Frauen und Männern mit hohem Bildungsniveau haben sich in den letzten Jahren die Einstellungen zur familialen Arbeitsteilung stark gewandelt. Mittlerweile wird eine partnerschaftlieh- egalitäre Verteilung der Pflichten im Haushalt mehrheitlich begrüßt. Um festzustellen, ob veränderte Einstellun· gen auch verhaltenswirksam geworden sind, wurden 66 Studentinnen und Studenten mit Kleinkindern mit Methoden der Zeitbudgetforschung zu Tagesablauf und Zeitverwendung befragt. Bei insgesamt im Vergleich zur Erwerbsbevöl· kerung hoher Gesamtbelastung waren auch hier Hausarbeit und Kinderbetreuung ungleich, und zwar zu Lasten der Frauen, verteilt. Studentinnen können daher wesentlich weniger Zeit in ihr Studium investieren als Studenten. Immerhin hatte eine relativ große Minderheit partnerschaftliehe Formen der Arbeitsteilung verwirklicht.
Talcott Parsons hatte den Interpenetrationsbegriff eingeführt, um strukturelle Beziehungen zwischen verschiedenen System arten erfassen zu können. Niklas Luhmann übernimmt den Begriff von Parsons und benutzt ihn nach weitreichenden Revisionen v. a. dazu, das Verhältnis von psychischen und sozialen Systemen auf den Begriff zu bringen. In dieser Intersystembeziehung spielt Sprache eine entscheidende Rolle. Ein systemtheoretisches Sprachkonzept, das dieser Vermittlungsleistung Rechnung trägt, steht jedoch noch aus; ein zentrales Desiderat dabei ist, den Widerspruch zwischen Sprache als systemübergreifender Vermittlungsinstanz und der autopoietischen Geschlossenheit von Systemen aufzulösen.
No abstract available
0-2A progenitor cells give rise to both oligodendrocytes and type-2 astrocytes in vitro. Whereas oligodendrocyte differentiation occurs constitutively, type-2 astrocyte differentiation requires extracellular signals, one of which is thought to be ciliary neurotrophic factor (CNTF). CNTF, however, is insufficient by itself to induce the development of stable type-2 astrocytes. In this report we show the following: (a) that molecules associated with the extracellular matrix (ECM) cooperate with CNTF to induce stable type-2 astrocyte differentiation in serumfree cultures. The combination of CNTF and the ECM-associated molecules thus mimics the effect of FCS, which has been shown previously to induce stable type-2 astrocyte differentiation in vitro. (b) Both the ECM-associated molecules and CNTF act directly on 0-2A progenitor cells and can induce them to differentiate prematurely into type-2 astrocytes. (c) ECM-associated molecules also inhibit oligodendrocyte differentiation, even in the absence of CNTF, but this inhibition is not sufficient on its own to induce type-2 astrocyte differentiation. (d) Whereas the effect of ECM on oligodendrocyte differentiation is mimicked by basic fibroblast growth factor (bFGF), the effect of ECM on type-2 astrocyte differentiation is not. (e) The ECM-associated molecules that are responsible for inhibitin~ oligodendrocyte differentiation and for cooperating with CNTF to induce type-2 astrocyte differentiation are made by non-glial cells in vitro. (f) Molecules that have these activities and bind to ECM are present in the optic nerve at the time type-2 astrocytes are thought to be developing.
During the past 50 to over 100 million years communities evolved in the tropics which attained unprecedented levels of biodiversity, strikingly represented by evergreen lowland rain forests offering home to more than 50% of all the world's extant species. Within only some 30 years human action reduced the area covered with tropical rain forests to about half of its former size, thereby negatively affecting local and global functions of the biosphere and exterminating an unknown number of species. With an exponentially increasing rate we are throwing away our and all future generations' biological heritage. We destroy the most complicated, scientifically most interesting living systems before we have gained any knowledge of their structures ,and dynamics. To understand the particular structures and dynamics of tropical communities means in the first place to understand the causes and consequences of their ten- to more than hundredfold higher alphadiversity (as compared to temperate systems). This problem has a historical dimension and a functional side requiring answers as to the nature of the proximate mechanisms of its maintenance. My review is only concerned with the latter aspect, and its maIn emphasis is on the gaps in our knowledge. Two sets of hypotheses have been developed for explaining the high within-commUnIty diversity. (1) According to the classical concept interspecific niche competition and subsequent niche separation are the main forces determining the structure of the community. These so-called equilibrium models have been contrasted in recent times with (2) non-equilibrium models. These models do not attribute the decisive role to interspecific competition. Strong niche overlaps are presumed to be very common within species-rich communities. Continuous stochastic local disturbances are assumed to prevent the achievement of any long-term equilibrium (climax) state. Being on the right spot at the right time is regarded as most important. Whether oneor a combination of both models provide the best key for understanding the structure of a special section within a community will certainly depend on many properties of the species at debate (mobility, disr.ersal, fertility etc.). For the vast majority of tropical organisms all such information is at present unavailable. The principles governing the structure of communities is just one of the very ,basic open problems. Another very prominent question is how the qualitatively very rich, however quantitatively poor resources are distributed among the members of highly diverse guilds of consumers and decomposers. Does the scarcity rather favour generalists or specialists, are small species overrepresented, are resources more extensively used than in temperate communities? One important property is fairly well established: Populations of most tropical species seem to be very small. Since a) in very many' cases distribution range is obviously very limited, since b) predator pressure is generally assumed to be higher in the tropics and c) recent - perhaps unduely generalized - results claim abundance fluctuations in the tropics fully comparable in their dimensions to those in the temperate zone, the question arises as to how these small populations can persist for seemingly long periods of time and avoid rapid extinction. Additionally treated PoInts concern detritivore communities, plant animal Interactions, key stone groups. Saving biodiversity in general and the tropical species and community richness in particular is one of the most urgent tasks of our generation, and biologists have to play a still more prominent role in this extremely important endeavor than they have in the past decades.
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.
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.
Pandinus imperator is a forest dweller of tropical West Africa. In the field, lobserved aggregations of up to 15 individuals. In the laboratory, mixed age groups of related and also unrelated animals lived jointly in terraria rarely showing within-group aggression or cannibalism. Brood-caring behavior of the mother influenced growth rate and survival probability of the young. With birth, mothers became very aggressive. To study family cohesion in Pandinus, experiments with family groups were conducted. Siblings aggregated around their mother. In choice experiments with two family groups, mothers were placed in enclosures that only the young were able to enter or to leave. Second instars significantly preferred the enclosure containing their own mother. Aggression among unrelated young of the same age was not observed. Feeding experiments studied the possible advantages of long-Iasting group living with regard to enhanced success in prey capture and its effect on growth of the young. Even groups of second instars were unable to subdue large prey on their own. Sibling groups with their mother removed suffered high mortality due to starvation and cannibalism compared to groups with mothers present. Here, young grew significantly faster: they shared the prey that only the mother was able to kill and dismember. Pandinus imperator has to be considered an intermediate subsocial scorpion.
Escherichia coU K-12 strains producing S-fimbrial adhesins, FlC fimbriae, and mutagenized fimbriae were tested in a binding assay with a renal tubular cell line. S-fimbrial adhesins and FlC fimbriae mediated bindlog to tubular cells. The SfaA, SfaG, and SfaS subunits of S fimbriae contributed to attachment. Site-specific mutations in the sfaS gene reduced binding. The Inhibitionprofile of FlC fimbriae resembled that of S fimbriae.
In a colorimetric assay using 4-( p-nitrobenzyl)pyridine (NBP) as a nucleophilic scavenger of alkylating agents, the nitrosation and alkylation reactions were investigated for a number of amino acids and derivatives. The alkylating activity increased with the square of the nitrite concentration. The nitrosation rate constants for aspartic acid, aspartame, and glycine ethylester ( = precursors C) were 0.08, 1.4 and ~ 0.2, respectively, expressed in terms of the pH-dependent \(k_2\) rate constant of the equation dNOCjdt = \(k_2\) • (C]· [nitrite]\(^2\) • The rates correlated inversely with the basicity of the amino group. The stability of the alkylating activity was astonishingly high, both in acid and at neutral pH. Half-lives of 500, 200, and 30 min were determined for aspartic acid (pH 3.5), aspartame (pH 2.5), and glycine ethylester (pH 2.5). Values of 60, 15, and 2 min; respectively, were found at pH 7. It is concluded that rearrangement of the primary N-nitroso product to the ultimate alkylating agent could be rate-limiting. The potential of nitrosated a-amino acids to bind to DN A in vivo was investigated by oral gavage of radiolabelled glycine ethylester to rats, followed irnmediately by sodium nitrite. DNA was isolated from stomach and liver and analysed for radioactivity and modified nucleotides. No indication of DNA adduct formation was obtained. Based on an estimation of the dose fraction converted from glycine ethylester to the nitroso product under the given experimental conditions, the maximum possible DNA-binding potency of nitroso glycine ethylester is about one order of magnitude below the methylating potency of N-nitrosomethylurea in rat stomach. The apparent discrepancy to the in vitro data could be due to efficient detoxification processes in mammalian cells.
We have assessed the role of tumour necrosis factor-a (TNF) during cutaneous leishmaniasis and demonstrated that significant levels of TNF were released by spleen cells from infected mice after in cirro restimulation with Leishmania major promastigotes. Spleen cells from both genetically resistant and genetically susceptible mice were equally capable of producing TNF. After challenge with bacterial endotoxin, TNF activity could also be demonstrated in the serum of L. mujor-infected mice and the titres correlated with the course of cutaneous disease in susceptible and resistant mice. TNF did not exert a direct leishmanicidal effect in uitro. Furthermore, our study indicated that macrophages are the source of L. major-induced TNF activity and that its elicitation is dependent on the presence of T cells. These findings suggest that TNF acts in concert with other cytokines produced during L. major infection and that its role depends on the composition of T cell subsets and cytokines present.
The gene coding for the sialic acid-specific adhesin SfaS produced by the S fimbrial adhesin (sfa) determinant of Escherichia coli has been modified by oligonucleotide-directed, site-specific mutagenesis. Lysine 116, arginine 118, and Iysine 122 were replaced by threonine, serine, and threonine, respectively. The mutagenized gene dusters were able to produce S fimbrial adhesin complexes consisting of the S-specific subunit proteins including the adhesin SfaS. The mutant clones were further characterized by hemagglutination and by enzyme-linked immunoassay tests with antifimbria- and anti-adhesin-specific monoclonal antibodies, one of which is able to block S-specific binding (Moch et al., Proc. Natl. Acad. Sei. USA 84:3462-3466, 1987). The lysine-122 mutantclone was indistinguishable from the wild-type clone in these assays. Replacement of Iysine 116 and ai'ginine 118, however, abolished hemagglutination and resulted in clones which showed a weak (Iysine 116) or a negative (arginine 118) reaction with the antiadhesin-specific antibody Al. We therefore suggest that Iysine 116 and arginine 118 have an inßuence on binding of SfaS to the sialic acid residue of the receptor molecule. Substitution of arginine 118 by serine also had a negative efl"ect on the amount of SfaS adhesin proteins isolated from the S fimbrial adhesin complex.
We have identified the major immunogenic structural proteins of the human foamy virus (HFV), a distinct member of the foamy virus subfamily of Retroviridae. Radiolabelied viral proteins were immunoprecipitated from HFV -infected cells by foamy virus antisera of human and non-human primate origin. Precipitated viral proteins were in the range of 31 K to 170K. Labelling of proteins with [\(^{14}\)C]glucosamine or with [\(^{35}\)S]methionine in the presence oftunicamycin, as well as endo-ß-N-acetylglycosaminidase Hand F treatment of [\(^{35}\)S]methionine-labelled proteins, revealed three viral glycoproteins of approximately 170K, 130K and 47K, most likely representing the env gene-encoded precursor, the surface glycoprotein and the transmembrane protein of HFV, respectively.
No abstract available
Junge und erwachsene Schachexperten und -novizen wurden bezüglich ihrer Behaltensleistungen für kurzzeitig dargebotene Schachstellungen und für Anordnungen geometrischer Körper miteinander verglichen. Die Ergebnisse zeigen eine differenzierte Wirksamkeit von Expertise in Abhängigkeit von der Vertrautheit mit dem zu Lernenden Material und von der Art der Aufgabenstellung. Je vorwissensbezogener das zu Lernende Material ist, desto deutlicher ist der Einfluß von Expertise auf Gedächtnisleistungen nachweisbar. Dies gilt in gleicher Weise für unmittelbare wie für längerfristige Behaltensleistungen und für den Lernfortschritt. Im Unterschied dazu zeigt sich weder bei der Vorhersage eigener künftiger noch bei der Bewertung erbrachter Gedächtnisleistungen ein systematischer Einfluß von Expertise.
The selective opioid mu receptor agonist dermorphin increased the locomotor activity of rats dose dependently at 1 0 to 1 00 pmol/kg i.c.v. Respiratory rate, relative tidal volume and respiratory minute volume also increased unrelated to changes in locomotor activity. Higher doses, on the other hand, produced catalepsy and respiratory depression. Pretreatment of the rats with the mu,-selective antagonist naloxonazine (10 mg/kg i.v.) blocked the stimulant locomotor and respiratory effects of low doses of dermorphin (1 0--1 00 pmol/kg), but potentiated the respiratory depressant effect of a high dose (1 0 nmol/kg) of dermorphin. The selective benzodiazepine antagonist flumazenil (5 mg/kg), which has been shown previously to antagonize catalepsy and respiratory depression produced by relatively high doses of dermorphin, did not antagonize the respiratory or locomotor stimulant effect of dermorphin. The data suggest that mu\(_1\)-opioid receptors are responsible for the low dose stimulant effects of dermorphin on locomotor activity and respiration whereas mu\(_2\) receptors mediate the respiratory depressant effect of dermorphin.
No abstract available
Five subtypes of muscarinic receptors have been distinguished by pharmacological and molecular biological methods. This report characterizes the muscarinic subtype present in human gastric mucosa by radioligand binding studies. The receptor density was 27 ± 6 fmol/mg protein and the tritiated ligand N-methylscopolamine had an affinity of (Kn) 0.39 ± 0.08 nM (n = 11). The M1 receptor selective antagonist pirenzepine and the M2 receptor selective ligand AF-DX 116 had low affinities of 148 ± 32 nM (n = 13) and 4043 ± 1011 nM (n = 3) K n , respectively. The glandular M3 antagonists hexahydrosiladifenidol and silahexocyclium had high affinities ofKn 78 ± 23 nM (n = 5) and 5.6 ± 1.8 nM (n = 3). The agonist carbachol interacted with a single low-affinity site and binding was insensitive to modulation by guanine nucleotides. Antagonist and agonist binding studies thus showed an affinity profile typical of M3 receptors of the glandular type.
Muscarinic receptors mediating acid secretion in isolated rat gastric parietal cells are of M3 type
(1990)
Five subtypes of muscarinic receptors have been identified by pharmacological and molecular biological methods. The muscarinic receptor subtype mediating acid secretion at the level of the parietal cell was unknown. Therefore, this study was performed to characterize muscarinic receptors on rat gastric parietal cells using the 3 subtype-selective antagonists hexahydrosiladifenidol and silahexocyclium, which have high affinity for glandular M3 subtypes, and AF-DX 116, which has high affinity to cardiac M2 receptors. The affinity of these antagonists was determined by radioligand binding experiments. In addition, their inhibitory potency on carbachol-stimulated inositol phosphate production was investigated. Inhibition of carbachol-stimulated aminopyrine uptake was used as an indirect measure of proton production. Both M3 antagonists, hexahydrosiladifenidol and silahexocyclium, had nanomolar affinities for parietal cell muscarinic receptors and potently antagonized inositol phosphate production with nanomolar Ki values. Silahexocyclium similarly antagonized aminopyrine accumulation while hexahydrosiladifenidol behaved as a noncompetitive antagonist. AF-DX 116 was a low-affinity ligand and a weak competitive antagonist at parietal-cell muscarinic receptors. It was concluded that muscarinic M3 receptors mediate acid secretion probably by activation of the phosphoinositide second messenger system in rat gastric parietal cells.
The present study served to investigate the ability of seven selective muscarinic antagonists to inhibit carbachol-induced drinking in the rat. The muscarinic antagonists were given by intracerebroventricular (i.c.v.) injection 1 min before the i.c.v. injection of carbachol (1 \(\mu\)g/rat). The M\(_2\) antagonist, methoctramine, was inactive up to 80.3 nmol/rat. The M\(_3\) antagonist, p-fluoro-hexahydro-sila-difenidol, elicited a modest (42%) but statistically significant inhibition of drinking only at 80 nmol/rat. On the other band, the selective M\(_1\) antagonists, (R)-trihexyphenidyl, o-methoxy-sila-hexocyclium and pirenzepine, produced a marked and dose-dependent inhibition of carbachol-induced drinking, their 1050 values being 0.51. 7.36 and 9.31 nmoljrat. Also the M\(_1\)/M\(_3\) antagonists, 4-diphenylacetoxy-Nmethylpiperidine methiodide and hexahydro-sila-difen.idol, were potent inhibitors of carbachol-induced drinking, their ID\(_50\) values (0.28 and 11.09 nmoljrat) being related to their pA\(_2\) values for M1 receptors in rabbi t vas deferens. These data suggest that carbachol-induced drinking may be mediated by activation of muscarinic M\(_1\) receptors.
The nature of good information processing is outlined as determined by intact neurology, information stored in long-term memory, and general cognitive tendencies, attitudes, and styles. Educators can promote the development of good information processing by promoting what is in long-term memory. This can be accomplished by teaching important literary, scientific, and cultural knowledge; teaching strategies; motivating the acquisition and use of important conceptual knowledge and strategies; and encouraging the general tendencies supporting good information processing. Good information processing can be produced by years of appropriate educational input. Good information processors cannot be produced by short-term interventions.
Neuropathie und Motorik
(1990)
No abstract available
To study the activation of HIV by human spumaretrovirus (HSRV) the long terminal repeats (LTRs) of HSRV, HIVl and HIV2 were examined with respect to their ability to function as transcriptional promoters in virus infected and uninfected cells. Transient transfections using plasmids in which the L TRs of the three viruses were coupled to the bacterial chloramphenicol acetyltransferase (CA T) gene revealed (i) the level of cat gene expression directed by the HSRV LTR was markedly increased in HSRV infected cells compared to uninfected cells, (ii) cat gene expression driven by the HIV1 LTR, but not by the HIV2 LTR could be enhanced upon HSRV infection, whereas (iii) neither in HIV1 nor in HIV2 infected cells an effect on HSRV LTR driven cat geneexpression was detected.
An infectious molecular clone (pHSRV) of the human Spumaretrovirus (HSRV) was constructed using viral DNA and cDNA clones. The infectivity of pHSRV was proven by transfection of cell cultures and subsequent infection of susceptible cultures with cell free transfection derlved virus. pHSRV derived virus produced foamy virus typical cytopathic effects in susceptible cultures. lnfected cells could be stained specifically with foamy virus antisera by means of indirect immunofluorescence. Radiolmmunoprecipltatlon revealed the presence of characteristic HSRV structural proteins in pHSRV infected cultures. By cotransfection of pHSRV and an indicator plasmid it was found that pHSRV is able to transactivate the viral L TR. Viral transcripts were found to be approximately 200 bases Ionger in pHSRV infected cultures compared to wildtype infected cultures. This difference is most likely due to an Insertion of DNA of non-viral origin ln the U3 region of the 3'L TR of the infectious clone.
The long terminal repeat (LTR) of the human spumaretrovirus (HSRV) was examined with respect to its ability to function as transcriptional promotor in virus-infected and uninfected cells. Transient transfections using a plasmid in which the 3' L TR of HSRV was coupled to the bacterial chloramphenicol cetyltransferase (cat) gene revealed that the Ievei of HSRV LTR-directed cat gene expression was markedly increased in HSRV-infected cells compared to uninfected cells. Northern blot analysis of cat mRNA from transfected cultures suggests that transactivation of HSRVdirected gene expression occurs at the transcriptionallevel.
Pharmacokinetic properties of the antimuscarinic drug [\(^3\)H]-hexahydro-sila-difenidol in the rat
(1990)
The pharmacokinetics of tritiated hexahydrosila- difenidol ([\(^3\)H]-HHSiD) were examined in rats. Furthermore, the distribution of radioactivity was studied by means of whole body autoradiography. After i. v. administration of 2.9 mg/kg HHSiD plus [\(^3\)H]-HHSiD to anaesthetized rats bearing a catheter implanted in the ductus choledochus and receiving a mannitol infusion, HHSiD was rapidly distributed and metabolized. Only 5% ofthe radioactivity was recovered in blood after 23 s and 0.4% after 2.5 h. 64% of the plasma radioactivity could be extracted with hexane from the samples taken 23 s after administration. 52% of the radioactivity was eliminated within 2.5 h, 13% by urinary and 39% by biliary excretion. Following oral administration of 8.6 mg/kg HHSiD plus [\(^3\)H]-HHSiD there was an absorption of approximately one fourth of the administered radioactivity within 4 h. By means of whole body autoradiography (i. v. injection) as well as by tissue distribution measurement the highest Ievels of radioactivity were found in bile, urine, lung, kidney, adrenals, liver and .pancreas. Thus, after i. v. administration to rats HHSiD is rather quickly distributed, metabolized and excreted. This explains its low antimuscarinic potency in vivo.