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Biomedical subjects

J Zimmermann

Publications and source records attributed to J Zimmermann.

123 records · Page 7Linked to original sources
PubMed1976

[Acute and chronic effects of carpipramine, clozapine, haloperidol and sulpiride on the metabolism of biogenic amines in the rat brain (author's transl)].

In acute and chronic experiments investigations were made concerning the effect of clozapine, haloperidol, sulpiride and carpipramine on MHPG, HVA and 5-HIAA in rat brain and on motor activity of the animals. The activity of the rats treated with clozapine and haloperidol was reduced on the first day. After 10 days of treatment this effected of clozapine was significantly diminished. The MHPG level increased slightly on the first day of treatment with all four drugs. This elevation was maintained after chronic treatment with carpipramine and sulpiride, whereas clozapine and haloperidol decreased the MHPG content. 5-HIAA values did not show significant changes in acute experiments, whereas in chronic ones there was an increase. Haloperidol and clozapine induced a strong increase of HVA which decreased after 11 days in those animals treated with haloperidol. In comparison to haloperidol, after clozapine application the percentage of HVA-increase was higher in the limbic system than in the nigrostriatum.

Animals↗
PubMedDate not supplied

High-throughput automated DNA sequencing facility with fluorescent labels at the European Molecular Biology Laboratory.

One of the aims of the facility is to develop and push the automated on-line DNA sequencing gel technology to its limit in sequence throughput, which may be somewhere around 100 kilobases of sequence per device per day. Key new developments were initiated and applied in operation on the European Molecular Biology Laboratory (EMBL) automated sequencer and its commercial version A.L.F. (Pharmacia). Sequencing speed was increased by a factor of 10-20, up to 1500 bases per hour per clone on ultrathin (about 100 microns) gels, while the resolution and reading length were extended to 1000 bases on gels with 50 cm separation length, using fluorescein-15-*dATP as the internal label. With our sequencing strategy, closing about 40% of the sequence with "walking" primers and F-15-*dATP as internal label, we sequenced both strands of a cosmid insert of 38.5 kb in length, each strand twice, in only 430 sequencing reactions and with average reading of 380 bases per reaction.

Base Sequence↗
PubMedDate not supplied

High-throughput evaluation of olefin copolymer composition by means of attenuated total reflection Fourier tranform infrared spectroscopy.

As a consequence of developing fully automated reactors for organic and organometallic synthesis and polymerizations combined with rapid on-line analysis, databases, and data mining, the analysis of polymers with respect to composition and properties has been speeded up. High-throughput evaluation of olefin copolymers requires fast measurements and high accuracy without tedious sample preparation such as pressing KBr pellets. This has been achieved by using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR spectroscopy) in conjunction with multivariate calibration in order to determine the composition of olefin copolymers such as ethene/propene, ethene/1-hexene and ethene/1-octene copolymers.

Journal Article↗
PubMedDate not supplied

New reactive coenzyme analogues for affinity labeling of NAD+ and NADP+ dependent dehydrogenases.

Reactive coenzyme analogues omega-(3-diazoniumpyridinium)alkyl adenosine diphosphate were prepared by reaction of omega-(3-aminopyridinium)alkyl adenosine diphosphate with nitrous acid. In these compounds the nicotinamide ribose is substituted by hydrocarbon chains of varied lengths (n-ethyl to n-pentyl). The diazonium compounds are very unstable and decompose rapidly at room temperature. They show a better stability to 0 degree C. Lactate and alcohol dehydrogenase do not react with any of the analogues. Glyceraldehyde-3-phosphate dehydrogenase reacts rapidly with the diazoniumpentyl compound. Decreasing the length of the alkyl chain significantly decreases the inactivation velocity. 3 alpha, 20 beta-Hydroxysteroid dehydrogenase reacts at 0 degree C with the ethyl homologue and slowly with the propyl compound. The butyl- and pentyl analogues do not inactivate at 0 degree C. Tests with 14C-labeled 2-(3-diazoniumpyridinium)ethyl adenosine diphosphate show that complete loss of enzyme activity results after incorporation of 2 moles of inactivator into 1 mole of tetrameric enzyme. 4-(3-Acetylpyridinium)butyl 2'-phospho-adenosine diphosphate, a structural analogue of NADP+, was prepared by condensation of adenosine-2,3-cyclophospho-5'-phosphomorpholidate with (3-acetylpyridinium)butyl phosphate, followed by hydrolysis of the cyclic phosphoric acid with 2':3'-cyclonucleotide-3'-phosphodiesterase. Because of the redox potential (-315 mV) and the distance between the pyridinium and phosphate groups, this analogue is a hydrogen acceptor and its reduced form a hydrogen donor in tests with alcohol dehydrogenase from Thermoanaerobium brockii. The reduced form of the coenzyme analogue also is a hydrogen donor with glutathione reductase. With other NADP+-dependent dehydrogenases the compound has been shown to be a competitive inhibitor against the natural coenzyme. The acetyl group reacts with bromine to form the bromoacetyl group. This reactive bromoacetyl analogue is a specific active-site directed irreversible inhibitor of isocitrate dehydrogenase.

Affinity Labels↗
PubMedDate not supplied

The involvement of protein kinase C isoenzymes alpha, epsilon and zeta in the sensitivity to antitumor treatment and apoptosis induction.

In order to obtain additional information on the involvement of protein kinase C (PKC) isoenzymes in the resistance of cells to anticancer drugs and in the induction of apoptosis, we employed antisense oligonucleotides to PKC alpha and PKC zeta, CGP 53506, a new inhibitor of PKC alpha, and cells overexpressing PKC alpha, PKC epsilon and PKC zeta. We found that in HeLa cells which express PKC alpha and zeta, down-modulation of either PKC alpha or PKC zeta with antisense oligonucleotides induced apoptosis. The PKC alpha selective inhibitor CGP 53506 reduced the proliferation rate of PKC alpha overexpressing NIH3T3 cells more than that of wild-type cells and induced apoptosis, indicating that such a PKC alpha inhibitor may be useful in the treatment of tumors overexpressing PKC alpha such as glioblastomas. NIH3T3 cells overexpressing PKC alpha were more resistant, whereas NIH3T3 cells overexpressing PKC epsilon or PKC zeta were more sensitive to treatment with cis-platin, adriamycin or gamma-irradiation compared to parental NIH3T3 wild-type cells. The observed resistance and sensitization corresponded to the extent of apoptosis induced by these treatments. Alterations in the expression of p53, bcl-2 and bax in the PKC isoenzyme overexpressing cells indicate that these proteins may be involved in the different sensitivities of these cells.

3T3 Cells↗
PubMedDate not supplied

[Tissue engineering: new treatment of cartilage alterations in degenerative joint diseases in horses--preliminary results of a long term study].

Degenerative alterations in fetlock joints of the forelimb are common diagnoses for horses. The hyaline cartilage has a low capacity to regenerate and the treatment by veterinarians is often insufficient. As a final result, horses with articular cartilage defects are often not able to take part in competitions anymore. To establish an autologous cartilage repair method, we set artificial lesions (8 mm in diameter) into the fetlock joints of the forelimb of three horses. These defects were closed with autologous chondrocyte implants, which were fixed with titan-suture-anchors. After 3, 12 and 24 months, biopsies were taken by arthroscopy. One horse was euthanized after 9, another one after 24 months. The repair tissue was examined histologically and by biochemical analysis of hydroxyproline and glycosaminoglycan, which are typical cartilage related substances. After 9 months, the integration of the implant into native cartilage was demonstrated by electron microscopy. After 24 months, histological staining showed a similar morphology of the cartilage repair tissue compared with the surrounding native cartilage. Biochemical analysis of typical cartilage matrix molecules revealed formation of hyaline-like cartilage within tissue engineered autologous chondrocyte transplants.

Animals↗
PubMedDate not supplied

Endotoxin-induced acute renal failure in rats: effects of L-arginine and nitric oxide synthase inhibition on renal function.

BACKGROUND: The regulation of renal hemodynamics is closely related to the L-arginine (L-Arg)/nitric oxide (NO) pathway. NO - metabolized from L-Arg - is capable of improving renal function in ischemic and toxic acute renal failure (ARF), while NO synthase (NOS) inhibition induces deterioration in renal function. The mortality rate in patients with septic shock is increased when treated with a non-selective NOS inhibitor, while the incidence of ARF requiring renal replacement therapy is unaffected. To date, there are no studies on the impact of NOS substrate (L-Arg) and inhibitor (L-NMMA) on renal function in early lipopolysaccharide (LPS)-induced ARF. METHODS: ARF was induced by intravenous (i.v.) LPS. Animals were treated with L-Arg, L-NMMA (NOS substrate and inhibitor), a combination of both or saline. Glomerular filtration rate (GFR), urine flow, fractional sodium excretion, excretion of NO metabolism stable end products and blood pressure (BP) were recorded at baseline, after ARF induction, during drug infusion and thereafter. RESULTS: L-Arg induced better GFR during infusion. Excretion of the NO metabolism end products was highest in the L-Arg group and lowest in the NOS inhibitor group. L-Arg administration had no influence on BP, while L-NMMA induced a slight elevation. CONCLUSIONS: We conclude that exogenous L-Arg exerts beneficial effects in early LPS-induced ARF in rats during drug infusion, while NOS inhibition has no influence on GFR. Subcellular compartmentalization of the L-Arg pool in cytoplasma and the rapid utilization of exogenous L-Arg in such a micro-environment could explain this effect, which has been observed in other ARF models and was called the "L-Arg paradox". In further studies the effects of early and prolonged administration of L-Arg in endotoxinemia should be investigated.

Acute Kidney Injury↗