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Biomedical subjects

J Schmidt

Publications and source records attributed to J Schmidt.

At least 811 records · Page 45Linked to original sources
PubMed1979

Starch metabolism in Pseudomonas stutzeri. II. Purification and properties of a dextrin glycosyl-transferase (D-enzyme) and amylomaltase.

Amylomaltase and disproportionating enzyme (D-enzyme) were purified to homogeneity from cell-free extracts of Pseudomonas stutzeri using a six-step procedure. The presence of both glycosyltransferases in the same organism has not been reported before. Molecular weight determination by gel chromatography gave a value of 74,000 for the amylomaltase and 115 000 for the D-enzyme. Two subunits of different molecular weight were found in each enzyme as proved by sodium dodecyl sulfate-gel electrophoresis. The optimum pH of amylomaltase and D-enzyme activity is 7.6--7.7. Action of both glycosyltransferases on different maltodextrins showed that amylomaltase is most active with maltotetraose, and the Km value for this substrate is 7.1 mM. D-Enzyme catalyzed glucose release from maltose (Km = 8.3 mM) at a higher rate than from maltotriose and maltotetraose. With maltotriose as initial substrate, D-enzyme forms glucose, maltopentaose, maltoheptaose, maltononaose, maltoundecaose as major products. Amylomaltase acts on maltotriose, maltotetraose, and maltopentaose to form a series of homologous 1,4-alpha-glucans. No essential chain-lengthening reaction occurred with maltohexaose.

Glucans↗
PubMed1979

Comparison of protein and DNA synthesis assays of guinea pig spleen lymphocytes after stimulation with influenza virus antigen and phytohemagglutinin.

Two in vitro-methods for demonstration of cell-mediated immune response are compared: Protein and DNA synthesis for detection of in vitro influenza virus antigen- and mitogen-induced lymphocyte stimulation. Guinea pig spleen lymphocytes sensitized with influenza virus antigen were tested in a microadaptation of the lymphocyte transformation test using 14C- or 3H-leucine and 3H-thymidine. As a positive control for T-cell stimulation PHA-induced lymphocyte stimulation was measured. The following results were obtained: 1. Kinetics of the incorporation of 14C-leucine and 3H-thymidine in lymphocytes incubated with optimal and suboptimal PHA-doses respectively are quantitatively similar but different in time. 2. The results of the protein- and DNA-synthesis stimulation assays were correlated against influenza virus antigens, this could not be described by the comparison of cellular and single humoral parameters. 3. The administration of influenza virus antigens in CFA induced a more intensive cell-mediated reaction than injections of antigens in aqueous suspensions, but the results of both methods of CMI were correlated. 4. The optimal CMI under the experimental conditions described is induced by an administration of 30 to 50 microgram virus protein per animal and by a combined intramuscular--intraperitoneal immunization procedure. 5. The measurement of the early stimulation of protein synthesis in the PSS-test is substantially more rapid than for the classical LTT.

Animals↗
PubMed1979

Purification and some properties of five endo-1,4-beta-D-xylanases and a beta-D-xylosidase produced by a strain of Aspergillus niger.

Five different xylanases and a beta-D-xylosidase in the culture medium of Aspergillus niger have been purified to homogeneity from 13- to 52-fold by a procedure of gel and hydroxylapatite chromatography. The strain was isolated from soil of the African equatorial forest. Gel chromatography of the purified enzymes indicated that three of the xylanases have molecular weights of 31,000 and the other two xylanases have molecular weights of 50,000. beta-D-Xylosidase has a molecular weight of 78,000. The pH curves of the xylanases were quite diverse and showed pH optima ranging from 4.0 to 6.5. Characteristic action patterns were obtained for each of the purified xylanases by gel chromatography of the xylan digests on Bio-Gel P-2. The enzymes degraded arabinoxylan by an endomechanism, producing L-arabinose, D-xylose, xylobiose, and a mixture of branched arabinose-xylose and D-xylose oligosaccharides. All xylanases seemed to be capable of liberating L-arabinose from either arabinoxylan or the arabinose-xylose oligosaccharides. Branched arabinose-containing D-xylose oligosaccharides were slowly hydrolyzed, so that these sugars accumulate in the digest. Two xylanases showed relatively broad substrate specificity and were able to degrade also crystalline cellulose. beta-D-Xylosidase showed optimal activity at pH 6.7 to 7.0 and at 42 degrees C. The Km for o-nitrophenyl-beta-D-xylopyranoside was 0.22 mM and xylotriose was hydrolyzed more rapidly than xylobiose.

Aspergillus niger↗
PubMed1979

[Effect of psychotropic drugs on somatosensory evoked cortical potentials].

The effects of some typical clinically tested psychotropic drugs were studied in acute experiments on awake rats. Potentials in somatosensory cortex were evoked by peripheral stimulation. Haloperidol, diazepam, medazepam, desipramin and a new substance, the MPP-sulton, caused significant modification in latency and amplitude of some components of the potentials. Between the effects of psychotropic drugs exist differences which, in turn, were clearly distinguishable from the modification of these evoked responses by unspecific narcotic effects of hexobarbital.

Animals↗
PubMed1979

Polythelia associated with disturbances of cardiac conduction.

The authors examined three groups of persons (hospitalized patients, outpatients, and school girls) and conclude that in the cases of polythelia the cardiac conduction disturbances occur considerably more frequently than in persons without polythelia. When polythelia and conduction disturbances occur frequently in a family, the coexistence of both disorders is most probably of hereditary origin.

Abnormalities, Multiple↗
PubMed1979

[Results obtained from more intensive antenatal and intranatal attention to gemini pregnancy at gynaecological hospital of Karl-Marx-Stadt region (author's transl)].

Studies undertaken into gemini births between 1968 and 1977 have shown that reduction in perinatal mortality has been obtainable from high-intensity programmes of antenatal and intranatal attention to multiparae. Perinatal mortality had accounted for 13.4 per cent, between 1968 and 1974, and dropped to 7.4 per cent, between 1975 and 1977. This achievement is analysed and discussed. More improvement may best be expected from earlier detection of gemini pregnancy and earlier action of intensive care.

Birth Weight↗
PubMed1979

Cell-mediated immunity to influenza virus antigen and mitogen in guinea pigs: measurement with a semimicro protein synthesis assay.

A rapid and precise method for the assay of cell-mediated immune response basing on protein synthesis stimulation of mitogen-activated guinea pig lymphocytes is modified in a way that enables the study of virus-immunological problems. When used as a micromethod it has the following advantages over conventional methods: short-term cell culture, need of low quantities of cells and rapid preparation of great numbers of samples for radioactivity measurements. In this study we report the results of comparative experiments on measuring lymphocyte stimulation after addition of PHA and stimulation of sensitized lymphocytes following contact with homologous influenza virus antigen in vitro. The most important reaction parameters are as follows: 5-6 . 10(5) spleen lymphocytes/microculture in microtiter plates, use of Eagles's MEM cell culture medium without leucine, supplemented with HEPES buffer and 10% autologous guinea pig serum; optimum lymphocyte stimulation by addition of 0.5 microliter PHA or 0.1-1.0 microgram virus protein/ml; immuno-stimulation by PHA can be measured in vitro already after 6 h and by influenzavirus antigen already after 24 h.

Animals↗
PubMed1978

Ligand responses of alpha-bungarotoxin binding sites from skeletal muscle and optic lobe of the chick.

Binding properties of detergent-solubilized receptors for alpha-bungarotoxin from skeletal muscle of the 13th day chick embryo and from optic lobe of the hatching chick were compared. It was found that both types of receptor are nicotinic, although they differ in their affinities for individual ligands and in the rank order of ligands. In contrast to the muscle receptor, the neuronal receptor binds the toxin in a reversible fashion (KD = 2.1 X 10(-10) M at 23 degrees C). Small ligands inhibit brain equilibrium procedures. Toxin and ligands compete for a single type of noninteracting site, and the ratio of toxin binding sites to ligand-binding sites is unity. The inhibitory potency of ligands parallels their ability, at higher concentrations, to accelerate receptor . toxin by interaction with the same site on the receptor derived from the optic lobe.

Animals↗
PubMed1978

Some observations on the binding patterns of alpha-bungarotoxin in the central nervous system of the rat.

Patterns of alpha-bungarotoxin (alphaBuTX) binding within the brain of the rat have been studied following one of the two procedures: (1) the intraventricular injection of 125I-labeled toxin followed by a survival period of 1--8 days before aldehyde perfusion, or (2) the incubation of fresh cryostat sections of brain tissue in dilute solutions of radioactive toxin. Appropriate controls with nicotine, curare, atropine and native alphaBuTX established that specific nature of the binding. The principal observations were that toxin binding sites are predominantly associated with central areas of the brain in direct receipt of sensory inputs (the main and accessory olfactory bulbs, superior colliculus, ventral lateral geniculate nucleus, cochlear nuclei, the substantia gelatinosa of the spinal cord and spinal trigeminal nucleus, the principal sensory nucleus of the trigeminal, and the dorsal column nuclei) and with limbic areas of the brain (hippocampus, amygdala, olfactory tubercle, medial mammillary nucleus, and the dorsal tegmental nucleus of Gudden). Toxin was not found to bind to cranial motor nuclei with the exception of the dorsal motor nucleus of the vagus and the nucleus ambiguus. The discrete distribution of clusters of silver grains within the granule layer of cerebellar folia I, IX, and X is described as well as the heavy labeling of the inferior and accessory olivary nuclei. In many areas of the brain silver grains were found to overlie cell bodies. It is suggested that this may reflect the presence of both membrane-bound toxin and internalized ligand following initial binding to a membrane receptor site. An attempt was made to correlate the localization of toxin binding sites with the terminal distributions of previously described cholinergic pathways. There appears to be a reasonably good agreement between the distribution of toxin receptors and proposed sites of cholinergic transmission within the hippocampus, interpeduncular nucleus and cerebellum. In most other cases however, lack of data precluded such correlations. The anatomical relationship of alphaBuTX binding activity and neurotransmitters other than acetylcholine is also considered.

Animals↗
PubMed1978

Purification and characterization of DNA polymerases from the plasmacytoma MOPC 104E and Abelson murine leukemia viruses.

RNA-dependent DNA polymerases of intracisternal A particles from the mouse plasma cell tumor MOPC 104E and of Abelson murine leukemia virus (A-MuLV) were isolated from particle preparations by Nonidet P40 and ultrasonic treatment and purified by column chromatography on DEAE-cellulose and phosphocellulose, followed by centrifugation in linear sucrose gradients. Both DNA polymerases were very similar in their elution patterns from phospho and DEAE-cellulose, template specificities, requirements for optimum activity and inactivation by anti-(reverse transcriptase) antiserum. They are associated with ribonuclease H activity. For molecular weight determinations, antibody-precipitated enzymes were bound to staphylococcal-protein-A-Sepharose, solubilized and run on dodecylsulfate/polyacrylamide gels. Their apparent molecular weight was estimated to be 80000.

Animals↗
PubMed1978

Mass spectroscopy of natural products. III--Mass spectrometric comparison of lysergic acid and 9,10-dihydrolysergic acid.

The influence of the 9,10-double bond in the ergoline skeleton on the fragmentation behaviour of lysergic acid and 9,10-dihydrolysergic acid is discussed. The main fragmentation pathways were determined using high resolution mass spectrometry and metastable ion studies. The 70 eV electron impact spectra are compared with the 12 eV electron impact spectra and the negative ion mass spectra (2--4 eV).

Ergolines↗