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Biomedical subjects

J Schmidt

Publications and source records attributed to J Schmidt.

At least 739 records · Page 41Linked to original sources
PubMed1983

[Studies on central and peripheral hemodynamics using radiocardiography and Xenon-133 muscle clearance in patients with essential hypertension].

Examination of 80 patients with essential hypertension revealed a significant correlation between the tonus of peripheral muscular arterioles on the one hand, and the stage and duration of hypertension and age of the patients, on the other hand. The correlation between arteriolar tonus and indicators of cardiac pump function was less marked. The results confirmed the close relationship between changes of peripheral blood bed and development of hypertension. The use of 133Xe half-period for measuring the peripheral arteriolar tonus proved a simple, but informative method adding an important indicator of peripheral haemodynamics to the results of haemodynamic examination.

Adolescent↗
PubMed1983

[Effect of desipramine and social isolation on neuronal activity in rat hippocampus].

Chronic treatment of rats with desipramine leads to an increase of hippocampal neurons with low spontaneous activity. After an isolation rearing period of three months an increased spontaneous activity is seen in the hippocampus of rats. Furthermore the hippocampal spontaneous activity is related to age. Opposite alterations of spontaneous activity in desipramine treated and socially isolated rats, respectively, as well as their relations to noradrenergic transmission processes are discussed. The isolation syndrome as a model to test substances with antidepressive properties is also reviewed.

Animals↗
PubMed1983

comparative analysis of cellular respiratory inhibition by substituted phenylglyoxal-bis-(4-methyl-3-thiosemicarbazone) zinc chelates.

Fourteen para-substituted phenylglyoxal-bis-(4-methyl-3-thiosemicarbazone) zinc chelates have been synthesized as inhibitors of cellular respiration and therefore as potential antineoplastic agents. Each chelate has been evaluated as an inhibitor of Ehrlich ascites tumor cell and of rat liver slice respiration. The molar I50 values for respiratory inhibition have been subjected to computerized correlation to delineate quantitative relationships between biological activity and chemical structure. Activity against the tumor cell model is characterized by a positive lipophilic and a detrimental steric influence while activity against rat liver slice displays only a weak positive lipophilic effect. Quantitative comparative analysis suggests that selective action against the tumor cell system can be improved by substituents which are electron withdrawing and lipophilic in nature.

Animals↗
PubMed1983

Dopamine release from striatum slices of rats at different age: influence of hypoxia.

During the maturation and aging of rats the dopamine release from striatum slices shows different dynamics in dependence on the stimuli used. Electrically evoked release is very constant. Amphetamine induced release is fully developed at the age of day 14 and declines after 9 months. The K+ stimulated release develops to a maximum at 10 weeks and decreases thereafter. The stimulus and age dependent inhibition of dopamine release after an 18 h hypoxic exposure may be the result of peroxidative reactions of membranous phospholipid components induced by free radicals. Adult rats exposed to a 200 h hypoxia reveal no change in dopamine release after the last exposure probably in consequence of adaptive processes of physiological protection, among other things, by scavenging of free radicals. Adult rats exposed to long term hypoxia postnatally during the growth spurt period of neuronal structures show an increased dopamine release and no posthypoxic release inhibition. Our data indicate that different mechanisms are operative during hypoxia in animals of different age.

Aging↗
PubMed1982

Chronic lymphocytic leukemia. A review of 745 cases and assessment of clinical staging.

Review of 745 cases of chronic lymphocytic leukemia show that clinical staging by either the Rai or Binet method is very valuable in assessment of patients at the time of diagnosis. There is a marked decrease in survival with advancing stage (19.9 years median survival for Rai Stage 0, and 2.5 years and 2.7 years for Rai Stages 3 and 4, respectively). The definition of anemia as Hb less than 11 g/dl as in the Rai staging method appears to give slightly better discrimination among the stages than the Binet staging procedure. Patients with splenomegaly alone (Binet stage 2), however, form a small but distinct group that should be recognized. These is little to be gained by subdividing further according to size of the lymph nodes.

Adult↗
PubMed1982

Covalently modified peptides isolated from aspartate aminotransferase after reaction with pyridoxal 5'-sulfate.

The apoenzyme form of cytosolic aspartate aminotransferase of pig hearts was allowed to react at room temperature with 1 equiv of pyridoxal 5'-sulfate. The resulting covalently modified enzyme was degraded with pepsin. Fluorescent tri-, tetra-, and hexapeptides were isolated and characterized as fragments of the active site sequence: Phe-Ser-Lys-Asn-Phe-Gly-Leu. This sequence contains a modified form (Lys) of lysine-258 that is known to form a Schiff base with pyridoxal phosphate in the active site. The peptides were further degraded by acid hydrolysis to give a fluorescent derivative of lysine with light absorption and chemical properties similar to those of the original modified enzyme. A related series of peptides were obtained from apoenzyme after reaction with the 5-carboxyethenyl analogue of pyridoxal 5'-phosphate.

Amino Acids↗
PubMed1982

4-hydroxyquinoline-3-carboxylic acids as inhibitors of cell respiration. 2. Quantitative structure-activity relationship of dehydrogenase enzyme and Ehrlich ascites tumor cell inhibitions.

Studies on dehydrogenase enzyme inhibition have been extended with the design, synthesis, and correlation analysis of 7-[(substituted-benzyl)oxy]-, 7-[(substituted-phenethyl)oxy]-, and 7([substituted-phenoxy)ethoxy]-4-hydroxyquinoline-3-carboxylic acids. Sixteen new congeners and the fifteen molecules previously synthesized have been tested against cytoplasmic malate dehydrogenase and lactate dehydrogenase, as well as against mitochondrial malate dehydrogenase. The lipophilic congeners show a clear specificity for inhibition of the mitochondrial enzyme. Correlation analysis of the data on the three enzymes allows a comparison of the binding sites in quantitative terms, while examination of the data on inhibition of ascites tumor cell respiration affords an indication of membrane transport. A newly developed high-pressure liquid chromatography based retention index is compared to the octanol-water pi constant as a model for hydrophobic interactions.

Animals↗
PubMed1982

A note on the application and evaluation of the buckle transducer for the knee ligament force measurement.

Knee ligament forces were directly measured with buckle transducers. Given a collection of buckle transducers with adequate rigidity and a variety of sizes to accommodate different ligamentous geometries, two potential problems remain when using the buckles 1) impingement of the transducers with bone, producing a false output; 2) ligament shortening due to buckle installation, potentially altering the distribution of ligament forces around the knee. This report describes our current buckle transducer designs and installation procedures, and presents data which demonstrated that the errors due to ligament shortening and bone impingement can be assessed and reduced to acceptable levels.

Humans↗
PubMed1982

Antiviral activity of hetarylhydrazones.

Some hetarylhydrazones showed antiviral activity against Mengo virus in vitro. The replication of influenza A and B viruses was affected neither in vitro (chick chorioallantoic membranes) nor in vivo (mice). Based on dose response curves of the active hetarylhydrazones the compound Z 98/69 appeared most effective in vitro. This compound neither inactivated the extracellular virus nor inhibited its adsorption and penetration; it reduced virus replication when added 1-3 hr after Mengo virus inoculation. As shown by plaque reduction test vaccinia virus was also inhibited. A partial inhibition of rhinovirus 1B multiplication was observed whereas other picornaviruses were not affected.

Animals↗