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- Klinik und Poliklinik für Allgemein-, Viszeral-, Gefäß- und Kinderchirurgie (Chirurgische Klinik I) (4)
Results are presented of cloning cDNA of procine growth hormone, analysis of its primary structure, and creation of a construction capable of expression of this cDNA in Esqheriahia coti cells. It is shown that in the population of mRNA coding porcine growth hormone, heterogeneity is noted which is manifested not only at the level of the nucleotide sequence, but also is reflected in the amino acid sequence of the mature hormone.
Die MHK-Werte von Desacetylcefotaxim gegen verschiedene, z. T. ampicillinresistente Stämme von Escherichia coH, die mit Hilfe einer Agardilutionsmethode erhoben wurden, waren höher als die von Cefotaxim und Ceftriaxon, jedoch niedriger als die von Cefoxitin. In einem Modell der systemischen Infektion der Maus mit einem plasmidtragenden, betalactamaseproduzierenden Stamm von E. coli führte die Therapie mit Desacetylcefotaxim zu einer starken Reduktion der Keime pro Leber. Im Vergleich zur Therapie mit Cefotaxim trat die protektive Wirkung aber verlangsamt ein. Desacetylcefotaxim ist also kein unnützes Abbauprodukt von Cefotaxim.
No Abstract available
No abstract available.
Zu den Wollmaßen in Nuzi
(1988)
Das Martin-von-Wagner-Museum besitzt eine seit langem bekannte Sammlung bedeutender 'pontischer' Vasen, die vor kurzem durch die Erwerbung einer Oinochoe dieser Gattung sinnvoll ergänzt werden konnte (Abb. 30-34. 38. 40-45). Denn obwohl in der 'pontischen' Keramik die Oinochoen nach den Amphoren die häufigste Gefäßform sind, war gerade diese Form in der Würzburger Sammlung bisher nur durch zwei kleine, atypische Exemplare vertreten gewesen. Die neu erworbene Oinochoe kann dagegen nach ihrer Größe, ihren Formmerkmalen und ihrer Bemalung als eine typische Vertreterio dieser Form innerhalb der 'pontischen' Gattung gelten.
In zwei Therapieeinrichtungen zur Drogen-Entwöhnungsbehandlung wurde bei 194 Dro- , genabhängigen untersucht, inwiefern Anamnesedaten und Persönlichkeits variablen eine Vorhersage der vorzeitigen Therapiebeendigung gestatten. Lediglich eine Variable wies für Patienten beider Behandlungseinrichtungen gleichermaßen prognostische Valenz auf: Patienten mit gerichtlicher Auflage schlossen die Therapie häufiger regulär ab als Patienten ohne Auflage. Oie Art der gerichtlichen Auflage oder auch die Dauer der noch ausstehenden Strafzeit korrelierten dagegen nicht mit der Art der Therapiebeendigung. Ansonsten gab es für beide Therapieeinrichtungen und für die verschiedenen Arten der vorzeitigen Beendigung (Entlassung bzw. Abbruch) unterschiedliche, manchmal auch entgegengesetzte, prognostische Kriterien. Ein Patient, der in einer Einrichtung abbruchgefährdet ist, kann in einer anderen Einrichtung gute Chancen haben, die Behandlung regulär abzuschließen. Aus der Literatur bekannte Kriterien wie zum Beispiel Alter und Schulbildung zeigten in dieser Studie nur in Abhängigkeit von der Einrichtung prognostische Valenz und dies spezifisch für Abbruch bzw. vorzeitige Entlassung. Andere Prädiktoren wie Geschlecht, psychische Auffälligkeiten und Depression korrelierten überhaupt nicht mit vorzeitiger Therapiebeendigung. Auch Patienten, die zu Beginn der Therapie als gering motiviert einzustufen sind, haben gute Chancen, die Behandlung regulär abzuschließen. Auf der Grundlage einer Diskriminanzanalyse der FPI-Items war eine vorzeitige Entlassung besser vorhersag bar als ein Therapieabbruch. Nach den Daten dieser Studie ist zu vermuten, daß bestimmte Kombinationen von Einrichtungs-, Therapeuten- und Patienten variablen einen Einfluß auf die Art der Therapiebeendigung haben.
In order to investigate the DNA localization within Ehrlich tumor cell nucleoli during mitosis, two recent immunocytochemical methods using either an anti-DNA or an anti-bromodeoxyuridine (BrdU) monoclonal antibody have been applied. In both cases, the immunogold labeling has been performed on ultrathin sections of cells embedded either in Lowicryl K4M or in Epon, respectively. Identical results are observed with both immunocytochemical approaches. In the interphase nucleolus, besides the labeling of the perinucleolar chromatin shell and of its intranucleolar invaginations which penetrate into the nucleolar body and often terminate at the fibrillar centers, a few gold particles are also preferentially found towards the peripheral region of the fibrillar centers. In contrast, the dense fibrillar component and the granular component are never labeled. During mitosis, the fibrillar centers persist at the chromosomal nucleolus organizing regions (NOR's) and can be selectively stained by the silver method. However, these metaphase fibrillar centers are no longer decorated by the DNA- or BrdU antibodies. These results indicate that until the end of prophase, rRNA genes are present inside the fibrillar center material, disappear during metaphase and reappear in reconstituting nucleoli during telophase. Thus, fibrillar centers appear to represent structures sui generis, which are populated by rRNA genes only when the nucleolus is functionally active. In segregated nucleoli after actinomycin D treatment, the DNA labeling is exclusively restricted to the perinucleolar chromatin blocks. These findings also suggest that the DNA content of the fibrillar center material varies according to the rRNA transcription level of the cells. The results are discussed in the light of the present knowledge of the functional organization of the nucleolus.
The distribution of DNA in Ehrlich tumour cell nucleoli was investigated by means of an immunocytochemical approach , involving a monoclonal antibody directed against double- and single-stranded DNA. Immunolabelling was performed . either before or after the embedding process. The postembedding labelling method allows better ultrastructural preservation than the preembedding labelling method. In particular, the various nucleolar components are well preserved and identifiable. In the nucleolus, labelling is particularly concentrated over the perinucleolar chromatin and over its intranucleolar invaginations, which penetrate the nucleolar body and often terminate at the fibrillar centres. In addition, aggregates of gold particles are found in the fibrillar centres, preferentially towards the peripheral regions. By contrast, the dense fibrillar component is completely devoid of labelling. The results seem to indicate that DNA containing the rDNA genes is located in the fibrillar centres, with a preference for the peripheral regions. This finding suggests that transcription of the rDNA genes should occur within the confines of the fibrillar centre, probably close to the boundary region of the surrounding dense fibrillar component. The results are discussed in the light of present knowledge of the functional organization of the nucleolus.
Die Synthese des (Hydroxymethyl)[(trimethylsilyl)methyl]silans (3) sowie des hiervon abzuleitenden Acetats 4 und Chlorformiats 6 wird beschrieben. 4 und 6 unterliegen einer thermisch induzierten Umwandlung zu den difunktionellen Silanen 5 bzw. 8. Die Umwandlungen 4 -> 5 und 6 -> 8 erfolgen gemäß einer Kinetik 1. Ordnung mit Halbwertszeiten von 10.0 bzw. 3.6 h (135 ° C, in C\(_6\)D\(_6\)).
Synthese und Eigenschaften von (Hydroxymethyl)dimethylgerman und (Hydroxymethyl)diphenylgerman
(1988)
Die (Hydroxymethyl)diorganylgermane (CH\(_3\))\(_2\)Ge(H)CH\(_2\)OH und (C\(_6\)H\(_5\))\(_2\)Ge(H)CH\(_2\)OH wurden - ausgehend von GeCl\(_4\) - durch eine jeweils vierstufige Synthese mit einer Gesamtausbeute von 15 bzw. 32% dargestellt (GeCl\(_4\) ---+ Cl\(_3\)GeCH\(_2\)Cl -> R \(_2\)Ge(Cl)CH \(_2\)Cl ->R \(_2\)Ge(OAc)CH\(_2\)OAc--) R \(_2\)Ge(H)CH\(_2\)OH; R = CH\(_3\) bzw. C\(_6\)H\(_5\) ). Die chemische Reaktivität der Germane (CH\(_3\))\(_2\)Ge(H)CH\(_2\)OH und (C\(_6\)H\(_5\))\(_2\)Ge(H)CH\(_2\)OH wird durch deren Ge-H- und 0-H-Bindung bestimmt.
Thirty strains of microorganisms (bacteria, yeasts, fungi and green algae) were tested as resting free cells for their ability to transform acetyldimethylphenylsilane (1) enantioselectively into (R)-(1-hydroxyethyl) dimethylphenylsilane [(R)-2]. The biotransformations were monitared by GC (packed OV-17 column), and the enantiomeric purities of the products isolated were determined by HPLC (cellulose triacetate column, UV detection). All microorganisms tested were found to reduce 1 enantioselectively to give (R)-2. Under the test conditions used, the yeast Trigonapsis variabilis (DSM 70714) was found to 1 exhibif the highest specific activity (1.5 mg product x g cell wet mass\(^{-1}\) x min\(^{-1}\) ), whereas the highest enantioselectivities were observed for the bacteria Acinetobacter ca lcoaceticus (ATCC 31012) (>95% ee), Brevfbacterium species (ATCC 21860) (90% ee) and Corynebacterium dioxydans (ATCC 21766) (>95% ee), the yeast Candida humico la (OSM 70067) (90% ee), the fungus Cunninghame lla e legans (ATCC 26269) (94% ee), as well as the cyanobacterium Synechococcus leopoliensis (94% ee).· From the green algae tested, Chlamydomonas reinhardii showed the highest.enantioselectivity (85% ee).
Increased efficiency of transfection of murine hybridoma cells with DNA by electropermeabilization
(1988)
Dispase-treated murine hybridoma cells (SP2/0-Ag14) were transfected with the G418 resistance gene bearing plasmid pSV2-neo by electropermeabilization with a high degree of efficiency. The cells were subjected to intermittent multiple high-voltage short duration (5 p.s) DC pulses at intervals of 1 min in a weakly conducting medium followed by selection in G418-containing medium. The transfection medium, temperature, pulse duration, and voltage were empirically determined by preliminary electropermeabilization experiments. Increasing the number of pulses resulted in a higher percentage of transfected cells, but a decrease in the number of viable cells, with the optimal transfectant yield resulting when five pulses of 10 kV jcm were administered. This method allows the rapid and efficient injection of DNA into mammalian cells, and permits the rapid production of stable, drug resistant hybridoma celllines for use in subsequent fusion experiments.
Am Beispiel von vier Koris l) (Téloua, Barghot, Tazolé, Oufaguédout) des südlichen Air-Vorlandes werden Beobachtungen zum aktuellen morphodynamischen Geschehen dieser Region vorgestellt. Durch die regionalen Unterschiede der durchschnittlichen jährlichen Niederschlagshöhen und durch unterschiedliche Charakteristika ihrer Einzugsgebiete können diese vier Koris als typische Vertreter verschiedener fluviatil/äolischer Formungsgruppen angesehen werden. Der Übergang von vorherrschend fluviatiler zu vorherrschend äolischer Formung liegt dabei im Bereich des Kori Oufaguédout, im östlichen Teil des Untersuchungsraumes. Hier konnte durch mehrere Schürfe auch der zeitliche Übergang zwischen beiden Formungskreisen in der jüngeren Reliefgeschichte nachgewiesen werden.
N-Acetyl-leukotriene E\(_4\) administered to conscious freely moving rats produced a dose-dependent vasoconstriction in the mesenteric vessels which led to profound reduction of blood flow to the gut. Renal and hindquarter blood flow and vascular resistance were not affected even by high doses of N-acetyl-leukotriene E\(_4\) . N-Acetyl-leukotriene E\(_4\) was 10-fold more potent than the thromboxane analog U-46619 and 1000-fold more potent than prostaglandin F\(_{2a}\) but 2-5-fold less potent than leukotriene D\(_4\)/E\(_4\) to induce mesenteric vasoconstriction. These data indicatc that N-acetylleukotriene E\(_4\) is a biologically active metabolite of peptide leukotrienes, and might play a role in cardiovascular derangements mediated by leukotrienes.
Tbe mechanisms mediating the etl'ects ofthyrotropin-releasing hormone (TRH) on the cardiovascular system were studied in the conscious rat. Intracerebroventricolar (i.c. v.) injection of TRH (8 pmol-80 nmollkg) induced dose-dependent lncreases in mean arterial pressure, heart rate, and cardiac index. Rindquarter blood Oow increased due to vasodilation, while an lncrease in renal and mesenteric vascular resistance caused a decrease in blood Oow in the respective organs. The plasma Ievels of norepinephrine a~d epinephrine were increased by TRH, while there was no change in plasma renin activity or vasopressin. Tbe cardiovascular actions of i.c. v. TRH were not in.fluenced by blockade of the renin-angiotensin system or vasopressin receptors. Tbe ganglion blocker chlorisondamine and the a 1- aod al-adrenoreceptor antagooist phentolamlne (2 mg/kg i.v.) abolished the increase in blood pressure and mesenteric vasoconstriction after i.c. v. TRH. Propranolol (2 mg/kg i. v.) blocked the TRH-ioduced increase in cardiac index, heart rate, and hindquarter blood flow. The hindquarter vasodllatlon lnduced by TRH was also blocked by the selective ß1-adrenocept9r antagonist ICI 188,551 (1 or 2 mg/kg i.v.), while tbe ,8,-adrenoceptor blocker practolol (10 mg/kg i.v.) had no eft'ect on the hindquarter vasodiJation produced by TRH but totally blocked the increase in cardiac Index. In adrenal demedullated rats, the systemic hemodynamic eft'ects ofi.c. v. TRH were dimlnished along with the decrease in renal blood flow and lncrease in renal vascular resistance; however, the iocrease in hfndquarter blood flow was attenuated only in adrenal demedullated rats pretreated with the sympathetlc blocker bretylium. The renal vasoconstriction induced by i.c. v. TRH was not abolished by renal denervation. In sinoaortic debufl'ered rats, the pressor, tachycardic, and mesenteric vasoconstrictor responses to centrally administered TRH were significantly potentiated. Taken together, these data soggest that the putative rieurotransmitter TRH may play a role in central regulation of cardiac functions and organ blood flow distribution through both tbe sympathetic nerves and the adrenal medulla. A pivotal roJe for ß1-adrenoceptors in mediation ofhindquarter vasodilation ls also demonstrated.
The ability of nerve growth factor to cause rapid activation of the Na+K+ pump of its responsive cells was examined by measuring the uptake of 86Rb+. A significant increase in 86Rb+ uptake in Ea chick dorsal root ganglion sensory neurons after NGF treatment was seen only if the cells had been damaged during the preparation procedure. Such damaged cells could not survive in culture in the presence of NGF, and undamaged cells that did survive in response to NGF exhibited no increased 86Rb+ uptake rate. Furthermore, cultured calf adrenal medullary cells did not show an increase in 86Rb+ uptake after treatment with NGF, although these cells respond to NGF with an increased synthesis of catecholaminergic enzymes. These results are incompatible with the hypothesis that the mechanism of action of NGF that promotes neuronal survival and enzyme induction results from an initial stimulation of the Na+K+ pump.
No abstract available
No abstract available
Die Kristall- und Molekülstrukturen der Akarizide Chlortrineophylstannan (Ia), Chlortris[ ( dimethylphenylsilyl)methyl]stannan (tb) und Trineophyl(1,2,4-triazol-1- yl)stannan-hemihydrat (2a · 0.5H\(_2\)0) wurden durch Einkristall-Röntgenstrukturanalysen bestimmt. Zu V ergleichszwecken wurde ausserdem die Struktur des 2,5-Dimethyl-2,5-diphenylhexans (Bineophyl, 4) untersucht. Die Knüpfung von drei sehr raumerfüllenden N eophyl-Resten an ein Zinnatom führt zu einer deutlichen Verzerrung der tetraedrischen Geometrie [ta: C-Sn-C 117.2°, C-Sn-Cl99.7°; 2a·0.5H20: C-Sn-C 116.9° (Mittelwert), C-Sn-N 100.2° (Mittelwert)]. Austausch der zentralen Kohlenstoffatome in den Neophyt-Substituenten von la durch Siliciumatome führt zu einer Verringerung des Raumbedarfs und dadurch zu einer erkennbaren Angleichung an die tetraedrische Geometrie [lb: C-Sn-C 113.3° (Mittelwert), C-Sn-Cl 105.3° (Mittelwert)].
In neueren Untersuchungen zur Mathematikerziehung im Elementarbereich wird verstärkt auf die Bedeutung kognitiver Prozesse (Strategien) für die erfolgreiche Bewältigung von Problemlöseaufgaben hingewiesen. Im vorliegenden Beitrag wird insbesondere auf das Wissen um kognitive Prozesse und deren Steuerung, also auf Metakognitionen eingegangen. Es wird zunächst eine Einführung in traditionelle Kategorien von Metakognition gegeben und dann auf eine Weiterentwicklung eingegangen, die als "Modell des kompetenten Strategie-Anwenders" bekanntgeworden ist. Dieses Modell wird dann als Grundlage für Empfehlungen benutzt, die darauf abzielen, den Mathematikunterricht effizienter zu gestalten.
Neuere Ansätze der Hochbegabtenforschung haben demonstriert, daß herausragende intellektuelle Fähigkeiten alleine noch keine kognitiven Höchstleistungen in späteren Lebensabschnitten garantieren. Insbesondere retrospektive Analysen der Daten genialer bzw. kognitiv hochproduktiver Persönlichkeiten lassen darauf schließen, daß neben Intelligenzmerkmalen auch Wissensaspekte und nichtkognitive Persönlichkeitsmerkmale entscheidend dafür verantwortlich sind, daß Höchstleistungen erzielt werden können. Im vorliegenden Beitrag wird ein Überblick über Studien gegeben, die den Einfluß bereichsspezifiscben Wissens auf kognitive Höchstleistungen darstellt, daß jedoch ab einem bestimmten Grenzwert intellektueller Fähigkeit allein das Ausmaß bereichsspezifischen Wissens in Kombination mit extremen Ausprägungen in nichtkognitiven Merkmalen wie Konzentrationsfähigkeit, Ausdauer und Erfolgsmotivation darüber entscheidet, ob intellektuelle Höchstleistungen erbracht werden können.
Ofall amphibians living in arid habitats, reed frogs (belonging to the super species Hyperolius viridiflavus) are the most peculiar. Froglets are able to tolerate dry periods of up to 35 days or longer immediately after metamorphosis, in climatically exposed positions. They face similar problems to estivating juveniles, i.e. enduranee of long periods of high temperature and low RH with rather limited energy and water reserves. In addition, they must have had to develop meehanisms to prevent poisoning by nitrogenous wastes that rapidly accumulate during dry periods as a metabolie consequenee of maintaining a non-torpid state. During dry periods, plasma osmolarity of H. v. taeniatus froglets strongly increased, mainly through urea accumulation. Urea accumulation was also observed during metamorphic climax. During postmetamorphic growth, chromatophores develop with the density and morphology typical of the adult pigmentary pattern. The dermal iridophore layer, which is still incomplete at this time, is fully developed within 4-8 days after metamorphosis, irrespective of maintenance conditions. These iridophores mainly contain the purines guanine and hypoxanthine. The ability of these purines to reflect light provides an excellent basis for the role of iridophores in temperature regulation. In individuals experiencing dehydration stress, the initial rate of purine synthesis is doubled in eomparison to specimens continuously maintained under wet season conditions. This increase in synthesis rate leads to a rapid increase in the thiekness of the iridophore layer, thereby effectively reducing radiation absorption. Thus, the danger of overheating is diminished during periods of water shortage when evaporative cooling must be avoided. After the development of an iridophore layer of sufficient thickness for effective radiation reflectance, synthesis of iridophore pigments does not cease. Rather, this pathway is further used during the remaining dry season for solving osmotic problems eaused by accumulation of nitrogenous wastes. During prolonged water deprivation, in spite of reduced metabolic rates, purine pigments are produced at the same rate as in wet season conditions. This leads to a higher relative proportion of nitrogen end products being stored in skin pigments under dry season conditions. At the end of an experimental dry season lasting 35 days, up to 38% of the accrued nitrogen is stored in the form of osmotically inactive purines in thc skin. Thus the osmotic problems caused by evaporative water loss and urea production are greatly reduced.
No abstract available
DNA Methylation in Rat Li ver by Daminozide, 1, 1-Dimethylhydrazine, and Dimethylnitrosamine. SAGELSDORFF, P., LUTZ, W. K., AND ScHLAITER C. (1988). Fundam. Appl. Toxico/. 11, 723-730. [methyP4C]Daminozide (succinic acid 2',2'-dimethylhydrazide; 37 mgjkg), l,l( 14C]dimethylhydrazine (UDMH; 19 mgtkg), and (14C]dimethylnitrosamine (DMNA; 0.1 mg/ kg) were administered by oral gavage to male Sprague-Dawley rats. After 24 hr, the animals were killed and DNA was purified from the livers to constant specific radioactivity. After enzymatic degradation of the DNA to the 3'-deoxynucleotides the Ievel of DNA methylation was determined by HPLC analysis. Radiolabeled 7-methylguanine (7mG) was identified by cochromatography with unlabeled 7mG added as standard after acidic depurination of DNA and HPLC analysis ofpurines and apurinic acid. All three compounds were found to methylate DNA. The relative potencies were 1:47:4900 for daminozide:UDMH:DMNA. With [methyPH]UDMH, the formation of7mG was investigated as a function of dose administered, at 20, 2, and 0.2 mgj kg. The methylation ofDNA was strictly proportional to the dose. The data were used to compare the Ievel of DNA alkylation derived from residues of daminozide and UDMH in treated apple with the genotoxicity of the intake of N-nitroso compounds in Germany and Japan. It is estimated that these residues could Iead to a DNA methylation in the Ii ver of about 6% of an average exposure to DMNA
Normativität versus libertas. Die Entwicklung der französischen Briefrhetorik im 16. Jahrhundert
(1988)
No abstract available
Primary structure is determined of an insertion of a clone isolated from the library of hypophyseal cDNA of cattle by hybridization with a probe specific for prolactin. Analysis of nucleotide sequences showed that in the process of cloning, reorganization occurred in structure of preprolactin cDNA, including an inversion of the 5'-terminal and deletion of the central section of cDNA. Nevertheless, from structure of cDNA, nucleotide sequences can be deduced of extended 5'- and 3'-terminal sections of preprolactin mRNA in cattle with lengths of 257 and 551 nucleotide residues, respectively. When these sequences are compared to those established previously, some differences were found in primary structure. The most important of them is the presence of an additional codon which codes alanine at the position (-22) of the signal peptide. It is suggested that heterogeneity of preprolactin mRNA of cattle in the section coding the signal peptide is the result of alternative splicing, as was shown for preprolactin mRNA in rats.
RNA polymerase I preparations purified from a rat hepatoma contained DNA topoisomerase activity. The DNA topoisomerase associated with the polymerase had an Mr of 110000, required Mg2+ but not ATP, and was recognized by anti-topoisomerase I antibodies. When added to RNA polymerase I preparations containing topoisomerase activity, anti-topoisomerase I antibodies were able to inhibit the DNA relaxing activity of the preparation as well as RNA synthesis in vitro. RNA polymerase II prepared by analogous procedures did not contain topoisomerase activity and was not recognized by the antibodies. The topoisomerase I: polymerase I complex was reversibly dissociated by column chromatography on Sephacryl S200 in the presence of 0.25 M (NH4hS04. Topoisomerase I was immunolocalized in the transcriptionally active ribosomal gene complex containing RNA polymerase I in situ. These data indicate that topoisomerase I and RNA polymerase I are tightly complexed both in vivo and in vitro, and suggest a role for DNA topoisomerase I in the transcription of ribosomal genes.
Certain autoimmune sera contain antibodies against a nucleolar ribonucleoprotein particle associated with 7-2-RNA (R. Reddy et al. (1983) J. Bioi. Chem . 258, 1383; C. Hashimoto and J. A. Steitz (1983) J. Bioi. Chem. 258, 1379). In this study, we showed by immunofluorescence microscopy that antibodies reactive with 7-2-ribonucleoprotein immunolocalized in the granular regions of actinomycin D and 5,6-dichloro-I-j3-D-ribofuranosylbenzimidazole (DRB)-segregated nucleoli from Vero cells. By electron microscopic immunocytochemistry, antigen-antibody complexes were located in the granular component of transcriptionally active nucleoli from rat liver hepatocytes and HeLa cells. Anti-7- 2-RNP antibodies from two autoimmune sera immunoprecipitated a major protein of Mr 40,000 from e5S] methionine-Iabeled HeLa cell extract. The immunolocalization data suggest that 7-2-ribonucleoprotein may be involved in stages of ribosome biogenesis which take place in the granular component of the nucleolus, i.e., assembly, maturation, and/or transport of preribosomes
No abstract available
The Escherichia coli blood culture isolate BK658 (07S:K1:H7) expresses F1A and F1B fimbriae as weil as a third fimbrial type which reacts with anti-S-fimbrial antiserum but fails to show S-specific binding properlies (i.e., agglutination of bovine erythrocytes). To characterize these fimbriae, we cloned the respective genetic determinant in E. coli K-12. The resulting recombinant clone HB101(pMMP658-6) expresses fimbriae of 1.2-p.m length and a diameter of approximately 7 nm. The determinant codes for the fimbrillin subunit, a protein of 17 kUodaltons in size, and for at least five other proteins of 87, 31, 23, 14.3, and 13.8 kUodaltons. By restriction analysis and by DNA-DNA hybridization, it could be shown that the cloned fimbrial determinant of strain BK658 exhibits a high degree of sequence homology to the gene clusters coding for S fimbrial adhesins (sfa) and F1C fimbriae (/oc). By using the Western blot (immunoblot) technique and a quantitative enzyme-linked immunosorbent assay, it could be further demonstrated that the cloned fimbriae of BK658, S fimbriae, and FlC fimbriae share cross-reactive epitopes as weil as antigenic determinants specific for each fimbrial type. No antigenic cross-reactivity with F1C fimbriae could be detected. The results indicate a genetical and serological relatedness of the cloned fimbriae toS fimbriae and F1C fimbriae. Therefore, this new type of fimbriae is preliminarily termed SIF1C-related fimbriae (Sfr).
Binding sites in the rat brain for Escherichia coli S fimbriae associated with neontal meningitis
(1988)
Escherichia coli strains that cause sepsis and meningitis in neonatal infants carry S fimbriae that bind to sialyl galactoside units of cell surface glycoproteins. To investigate the possible role of S fimbriae in determining the tissue tropism of neonatal menlngitis, we have studied the preselice of binding sites for S fimbriae in different tissues of the neonatal rat which is susceptible to meningitis caused by S-fimbriated E. coli. Purified S fimbriae were incubated on cryostat sections of different rat oipns and their bindina was assessed by indirect immunofluorescence. In the bnin of the neonatal rat, S fimbriae specifically bound to the luminal surfaces of the vascular endothelium and of the epithelium lining the choroid plexuses and bnin ventricles. The · bindlog W.s completely inhibited by the trisaccharide NeuAca2-3Ga)ßl-4Gic, a receptor analogue of S fimbriae, and by a preceding neuraminidase treatment of the sections. A recombinant E. coli strain expressina S fimbriae adhered in large numbers to the same tissue sites in the neonatal brain sections as did the purified fimbriae, · whereas the nonfimbriated host strahi and a recombiiuuit strain expresslog P fi.mbriae did not adhere to brain tissues. The results soggest that adhesion of S-fimbriated bacteria to the binding sites observed in the neonatai bnin has a pathogenetic roJe durlog bacterial Invasion from cii'culation into the cerebrospinal fluid.
Fimbrial 8dhesins en8ble b8cteria to 8ttach t9 eucaryotic ceU~. The genetic determin8nts for S fimbrial 8dhesins (sja) an.d for FlC ("pseudotype I") fimbri8e ifoc) were compared. Sfa and FlC represent functionally distinct 8dbesins in tbeir receptor specificities. Nevertheless, 8 high degree of bomology between both determin8nts was found on the basis of DNA-DNA hybridizations. Characteristic difl'erences in the restriCtion maps of tbe corresponding gene clusters, bowever, were visible in regions coding for the fimbrial subunits and for the S-specific 8dhesin. While a plasmid carrying the geneiic deternlinant for FlC fimbri8e was 8ble to complement transposon-induced sfa mutants, 8 plasmid carrying tbe genetic determin8nt for 8 tbird 8dht$in type, termed P fimbriae, was un8ble to do so. Proximal sfa-specific sequences carrying the S fimbrial st'"uctural gene were fused to sequences representing tbe di$tal part of the foc gene cluster to form 8 hybrid cluster, and tbe foc proxim~ region coding for tbe structural protein was Iigated to sfa distal sequences to form 8 second hybrid. Botb hybrid clones produced intact fimbriae. Anti-FlC monoclonal8ntibodies (MAbs) only recognized clones which produced FlC fimbriae, and an ~ti-S 8dhesin MAb marked clones whicb expressed the S adhesin. Bowever, one of four other anti-S fimbri8e-specific MAbs reacted witb both fimbrial structures, S and FlC, indicating 8 common epitope on both antigens. The results presented bere ~upport tbe view th8t sfa and foc determinants code for fimbri8e tb8t 8re simil8r in several aspects, wbile the P fimbri8e are members of 8 more distantly rel8ted group.
In Xiphophorus the causative, primary cellular oncogene for melanoma formation has been assigned by classical genetics to a sex-chromosomal locus, designated Tu. Activation of Tu was proposed to be the result of the elimination of Tu-specific regulatory genes which normally suppress the transforming function in the nontumorous state. In order to understand the role which known proto-oncogenes migbt play in this process, we have analysed the expression of src, erb A, erb B, ras, abl, sis and mil related genes from Xiphophorus during embryogenesis, in non-tumorous organs and in melanoma cells. For src, ras, erb B and sis a differential expression during embryogenesis and/or in normal organs was detected, with preferential expression of src in neural tissues, a high abundance of sis transcripts in an embryonal epitheloid cellline and of erbB transcripts in the head nephros. In melanoma cells ras, src and a v-erb B related gene were found to be expressed. The src gene most likely is more involved in secondary processes during tumor progression, while the expression of the v-erb B related gene might be transformation-specific because recently such a sequence was found to map to the close vicinity of the Tu-locus.
We analyzed an Escherichia coli strain which harbours a chromosomal mutation that blocks the hemolysin excretion. Compartmentation studies showed that hemolysin accumulates in the cytoplasm and not in the periplasm. The mutation did not affect the SDS-PAGE protein pattern of the outer membrane, although some alterations were apparent in the periplasmic protein pattern. The mutant strain, E. coli Hsb-1 also failed to export a cloned fimbrial adhesin. The mutation maps in the min. 3.5 of the E. coli genetic map.
Syngeneic memory cells can be stimulated to yield a secondary immune response after their transfer into irradiated euthymie recipients as well as into young thymusless nude mice. It is shown that nude mice older than twelve weeks of age are not permissive towards memory cell activation as it is found in non-irradiated euthymie animals. This barrier to isogeneie or congeneic cells seems to be caused by a pool of cyclophosphamide-sensitive cells. Since young nude mice could be rendered as unpermissive as older nude mice by pretreatment with either PNA-agglutinable thymus cells or nylon-wool passed spleen cells, it is suggested that an increased number of precursor T cells in older nude mice might induce this effect. Further experiments with monoclonal antibodies against the Lyt-l, Lyt-2, and L3T4 marker on T cells indicate that T -helper/inducer activity might be required to establish the "isogeneie barrief" in nude mice.