PubMed Health⌕ Search

Biomedical subjects

J Fiedler

Publications and source records attributed to J Fiedler.

16 recordsLinked to original sources
PubMed1992

Cloning and sequence analysis of genes for dehalogenation of 4-chlorobenzoate from Arthrobacter sp. strain SU.

Strains of Arthrobacter catalyze a hydrolytic dehalogenation of 4-chlorobenzoate (4-CBA) to p-hydroxybenzoate. The reaction requires ATP and coenzyme A (CoA), indicating activation of the substrate via a thioester, like that reported for Pseudomonas sp. strain CBS3 (J. D. Scholten, K.-H. Chang, P. C. Babbit, H. Charest, M. Sylvestre, and D. Dunaway-Mariano, Science 253:182-185, 1991). The dehalogenase genes of Arthrobacter sp. strain SU were cloned and expressed in Escherichia coli. Analyses of deletions indicate that dehalogenation depends on three open reading frames (ORFs) which are organized in an operon. There is extensive sequence homology to corresponding gene products in Pseudomonas sp. strain CBS3, suggesting that ORF1 and ORF2 encode a 4-CBA-CoA-ligase and a 4-CBA-CoA dehalogenase, respectively. ORF3 possibly represents a thioesterase, although no homology to the enzyme from Pseudomonas sp. strain CBS3 exists.

Amino Acid Sequence↗
PubMed1991

Cortical ablation reduces veratridine evoked release of endogenous glutamate from superfused substantia nigra slices.

A brain slice superfusion system and HPLC coupled to fluorometric detection were used to study depolarization-evoked release of endogenous glutamate (Glu) and aspartate (Asp) from substantia nigra (SN) slices. Veratridine (15-25 microM) and K+ (50 mM) evoked both a Ca2(+)-dependent and Ca2(+)-dependent release of Glu and Asp. However, the pattern of Glu release was different from that of Asp. In addition, cortical ablation significantly reduced the evoked release of Glu but not that of Asp. There results indicate the existence in SN of functional Glu- and Asp-releasing nerve terminals. Some of the Glu-enriched nerve terminals might belong to a cortico-nigral neuronal pathway.

Animals↗
PubMed1991

Cyanide sensitive and insensitive bioenergetics in a clonal neuroblastoma x glioma hybrid cell line.

The primary mechanism of cyanide (CN) intoxication is the inhibition of metabolism in the central nervous system. We determined the effects of CN on several biochemical processes in neuroblastoma x glioma hybrid NG108-15 cells, which possess numerous neuronal properties. These cells were not sensitive to a high concentration (1 mM) of NaCN, but became sensitive in the presence of the anaerobic glycolysis inhibitors sodium iodoacetate (IA) and 2-deoxyglucose (2-DG):cellular metabolic processes (e.g., DNA, RNA and protein synthesis) decreased to about 40% of control due to treatment with 0.5 mM NaCN + 0.05 mM IA and 0.1 mM NaCN + 20 mM 2-DG. ATP in cells exposed to 0.01 or 0.1 mM NaCN + 20 mM 2-DG was reduced 75% and 100% respectively within one min. Pretreatment of cells with the CN antidote cobalt (II) chloride (CoCl2) (0.06-0.18 mM) for 5 min prevented the depression of both [3H]leucine incorporation and ATP synthesis due to 1 mM NaCN + 20 mM 2-DG in a concentration-dependent manner. A proposed CN antidote alpha-ketoglutaric acid (disodium salt) also prevented the depression of cellular metabolism due to NaCN plus 2-DG. These results indicate that blocking anaerobic glycolysis makes NG108-15 cells sensitive to a low concentration of CN. Thus NG108-15 cells should be useful to study the mechanisms of neurotoxicity of CN and to test antidotes.

Adenosine Triphosphate↗
PubMed1991

Self-help quit smoking interventions: effects of self-help materials, social support instructions, and telephone counseling.

Smokers requesting self-help materials for smoking cessation (N = 2,021) were randomized to receive (a) an experimental self-quitting guide emphasizing nicotine fading and other nonaversive behavioral strategies, (b) the same self-quitting guide with a support guide for the quitter's family and friends, (c) self-quitting and support guides along with four brief counselor calls, or (d) a control guide providing motivational and quit tips and referral to locally available guides and programs. Subjects were predominantly moderate to heavy smokers with a history of multiple previous quit attempts and treatments. Control subjects achieved quit rates similar to those of smokers using the experimental quitting guide, with fewer behavioral prequitting strategies and more outside treatments. Social support guides had no effect on perceived support for quitting or on 8- and 16-month quit rates. Telephone counseling increased adherence to the quitting protocol and quit rates.

Behavior Therapy↗
PubMed1990

A study in rat brain cortex synaptic vesicles of endogenous ligands for N-methyl-D-aspartate receptors.

The presence of endogenous ligands for the N-methyl-D-aspartate receptor was looked for in highly purified rat brain cortex synaptic vesicles, the contents of which were extracted and fractionated by gel filtration on Sephadex G-10, or by three different high-voltage electrophoresis procedures. The presence of endogenous ligands was detected by their ability to compete with 50 nM L-[3H]glutamate for binding to whole rat brain N-methyl-D-aspartate receptors. The receptor preparations used were those present in purified postsynaptic densities, in which the quisqualate receptors were blocked by 10 microM quisqualate. Synaptic vesicles had a high content of N-methyl-D-aspartate receptor ligands, which on fractionation always coincided with glutamate or aspartate. A variable and very small amount of a highly acidic endogenous ligand was also found. The latter substance did not coincide in the electrophoresis with homocysteic, cysteic, quinolinic, cysteine sulphinic or homocysteine sulphinic acids, or with N-acetyl-aspartyl-glutamic acid, S-sulphocysteine or sulphoserine. We also found that a single centrifugation, in 0.25 M sucrose, 25 mM Tris-citrate, pH 7.1, of purified synaptic vesicles, at 135,000 gmax for 45 min, led to a 51% loss of endogenous glutamate, but did not change their aspartate content. Thus, in uncentrifuged vesicles the glutamate/aspartate ratio was 9.4, while in centrifuged ones the ratio was 3.9 ATP markedly enhanced L-[3H]glutamate uptake into synaptic vesicles, but did not change the binding of L-[3H]aspartate. Differences in labelled aspartate and glutamate efflux from the vesicles were also found.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1990

[Rapid glutamic acid decarboxylase test for identification of Escherichia coli].

A rapid, one-step glutamic acid decarboxylase test for the identification of Escherichia coli is described. The test gives a positive reaction (definite blue color) after 2 h to 3 h. Disturbing factors were explained. Microorganisms were cultured to Endo agar (SIFIN) supplemented with 1% meat peptone (Berlin-Chemie). For rapid liberation of the enzyme a combination of lytic agents NaCl and Triton X-100 were necessary. A total of 6,867 strains of Enterobacteriaceae of clinically isolates were parallely tested to activity of lactose, indole, citrate respectively biochemical tests with 15 reactions on the one side and activity of lactose and glutamic acid decarboxylase on the other side. 99.2% of the E. coli strains gave a positive reaction with glutamic acid decarboxylase. The rapid test selected E. coli with more reliability than the combination of the lactose, indole and citrate reactions. Expenditure of time and materials was fewer.

Bacteriological Techniques↗
PubMed1979

[Hepatological aspects of surgical interventions in the stomach].

By means of quantitative-biochemical and histomorphological methods after vagotomies changes of the liver could be proved to a smaller extent than after resections of the stomach (Billroth II). Among the bionomic operation methods the supra-selective proximal vagotomy without pylorplastics is superior to other methods under the aspect of the change of the liver.

Gastrectomy↗
PubMed1978

[The effectivity of long-term treatment of porphyria cutanea tarda from a hepatological viewpoint].

34 Patients with an ascertained porphyria cutanea tarda who underwent a long-term therapy a comprehensive internal and hepatological diagnosis was made. In these cases for the first time the estimation of the intrahepatic distribution of enzymes and its comparison with the serum enzymes were also performed. The liver histology allowed a division of our patients into three groups, in which cases the reactive hepatitides prevailed and a conspicuously large proportion of normal histological findings were present. The comparison of all data got with the literature made the conclusion possible that the phlebotomy therapy as well as the care in a special dispensary for years lead to very favourable results on liver and skin.

Bloodletting↗
PubMed1977

Inhibition of T-antigen-binding cells by idiotypic antisera.

Shared idiotypy between B- and T-cell receptors specific for the antigen L-tyrosine-p-azophenyltrimethylammonium [tyr(TMA)] was studied in an antigen-binding assay using idiotypic antisera. These idiotypic reagents were prepared by inoculation of rabbits with purified anti-tyr(TMA) antibody raised in strain 13 guinea pigs. The antisera blocked 78-83% of the antigen-binding T cells (T-ABC) and 50-55% of the antigen-binding B cells (B-ABC) from tyr(TMA)-immune strain 13 and outbred lymph node cells (LNC). An excess of normal guinea pig Ig in the ABC assay did not affect the ability of the idiotypic antisera to block T- and B-ABC. Nylon wool-passed tyr(TMA)-immune LNC were trypsin treated resulting in a 75% loss of T-ABC. The trypsin-treated population was then cultured for 16 h which resulted in a return of T-ABC to 92% of pretrypsin values. 77% of these regenerated T-ABC could be blocked with idiotypic antisera. Specificity of the idiotypic antisera was tested in L-tyrosine-p-azobenzenearsonate-immune guinea pig LNC. Neither T- nor B-ABC were blocked in this heterologous system. Further blocking experiments were performed to characterize the nature of the T-ABC receptor. A variety of anti-Ig reagents, some of which block B-ABC, do not inhibit T-ABC suggesting that variable regions on T cells are not linked to Ig Constant regions.

Animals↗
PubMed1977

[Analysis of etofenamate. Particular determination in biological material (author's transl)].

The determination of 2-(2-hydroxyethoxy)-ethyl-N-(a,a,a-trifluoro-m-tolyl)-anthranilate (etofenamate, active principle of Rheumon gel) following its isolation from biological material is reported. Depending on the method of extraction etofenamate, free and alkali-labile conjugated flufenamic acid, total conjugates or the sum of CF3-containing compounds (sum of metabolites) are isolated. Separation is achieved by TLC, quantitative determination is made by degradation to flufenamic acid and fluorimetric measurement in CCl4/trichloracetic acid at 372/445 nm. Etofenamate can be identified by TLC, derivatisation, UV- and fluorescence spectroscopy and differentiated from its metabolites. It is demonstrated that etofenamate is the main component of fenamates in inflamed tissue.

Animals↗
PubMed1976

Endocrine-metabolic response to acute starvation in human gestation.

During a 72 hour fast in pregnant women, significant decrements in the maternal plasma glucose concentrations, accompanied by a significant increase in the plasma placental lactogen (hPL) concentration, occur. At the same time, utilization of glucogenic amino acids, principally alanine, takes place. The mean postprandial glucose concentration in pregnancy is significantly lower than that of comparable nonpregnant women (70.5 +/- 1.7 versus 79.5 +/- 1.3 mg. per 100 ml., p less than 0.001). There appears to be a significant sparing effect on the maternal plasma glucose concentration during acute fasting which may be mediated through hPL. Concentrations of amniotic fluid and fetal plasma glucose from women undergoing fasting decrease in a manner parallel to that of the mother. Fasting provokes a mean rise in plasma hPL of 33.2 per cent over basal levels. This rise is still evident 72 hours after refeeding, after which it gradually returns to pretest concentrations. The infusion of alanine or arginine to pregnant women at the end of the fast produced increments in the peripheral maternal glucose concentration. The response was much greater with alanine than with arginine, demonstrating the increased gluconeogenic potential of this amino acid. The increment in human growth hormone (hGH) following alanine infusion was significantly greater than that observed after arginine administration. Hypoaminoacidemia was present in nonpregnant and pregnant women in response to fasting, but the decline was greater in pregnancy. Acute fasting in the first half of gestation appears to produce significant alterations in carbohydrate metabolism evidenced by profound hypoglycemia, hypoinsulinemia, and hypoaminoacidemia. This maternal deficit can be reflected in fetal substrate concentrations. The effect of these changes on fetal growth and development is speculative at this time.

Abortion, Therapeutic↗