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Biomedical subjects

G Wagner

Publications and source records attributed to G Wagner.

At least 613 records · Page 34Linked to original sources
PubMed1978

Potassium uniport and ATP synthesis in Halobacterium halobium.

Light-driven potassium ion uptake in Halobacterium halobium is mediated by bacteriorhodopsin. This uptake is charge-balanced by sodium ions and not by proton release. Light-induced shifts in concentrations of divalent cations were found to be negligible. The transient changes in extracellular pH (alkaline overshoot) can be understood by the concomitant processes of ATP synthesis, proton/sodium exchange and potassium uptake. The driving force of potassium ion uptake is the membrane potential, no ATP-dependent potassium transport process is found. Fluorescence measurements indicate a high permeability of the membrane to potassium ions compared to sodium ions. Therefore the potassium ion diffusion potential contributes to the membrane potential (about 30 mV/decade) and thereby influences the ATP level. Sudden enhancement of the diffusion potential by the potassium ionophore monactin leads to the expected transient increase in cellular ATP level. Due to the large size (up to 100-fold) of the potassium ion gradient and its high capacity (intracellular concentration up to 3 M) the potassium ion gradient can well serve the cell as a long term storage form of energy.

Adenosine Diphosphate↗
PubMed1978

[The mitral valve in echocardiography].

In echocardiographic investigations the mitral valve occupies a central position. Its pathological changes in the echocardiogramme in the diseases of the mitral valve itself as well as in other cardiopathies are described. Apart from the morphological estimation the measuring methods are discussed.

Aortic Valve Insufficiency↗
PubMed1978

Individual assignments of the methyl resonances in the 1H nuclear magnetic resonance spectrum of the basic pancreatic trypsin inhibitor.

In earlier work the resonances of the 20 methyl groups in the basic pancreatic trypsin inhibitor (BPTI) had been identified in the 360-MHz 1H nuclear magnetic resonance (NMR) spectra and most of the methyl lines had from spin-decoupling experiments been assigned to the different types of amino acid residues. The assignments to the different amino acid types were now completed by studies of the saturation transfer between the denatured and the globular forms of the inhibitor and by spin-decoupling experiments in nuclear Overhauser enhancement (NOE) difference spectra. These distinguished between the methyl resonances of Ala and Thr. Furthermore, for most of the methyl resonances, individual assignments to specific residues in the amino acid sequence were obtained from measurements of intramolecular proton-proton NOE's, use of lanthanide NMR shift and relaxation probes, and comparative studies of various chemically modified forms of BPTI. These data provide the basis for individual assignments of the methyl 13C NMR lines in BPTI and for detailed investigations of the relations between the spatial structure of the protein and the chemical shifts of the methyl groups. The methyl groups in BPTI are of particular interest since they are located almost exclusively on the surface of the protein and thus represent potential natural NMR probes for studies of the protein-protein interactions in the complexes formed between BPTI and a variety of proteases.

Alanine↗
PubMed1978

Oxygen tension of the vaginal surface during sexual stimulation in the human.

An oxygen electrode was maintained by suction on the vaginal wall in seven women. The basal value of pO2 was 9.3 mm Hg +/- 10.7 (mean +/- standard deviation) before clitoral self-stimulation was initiated. When stimulation took place the oxygen tension rose and peaked immediately after orgasm to 39.5 +/- 14.1 mm Hg. It then declined and fell to 20.1 +/- 13.8 mm Hg 10 minutes after the peak value. The changes correlate closely with changes in vaginal blood flow. The increased oxygen tension may be one of the factors that enhance of even initiate the motility of spermatozoa when deposited intravaginally.

Adult↗
PubMed1978

A 1H nuclear-magnetic-resonance study of the conformation and the molecular dynamics of the glycoprotein cow-colostrum trypsin inhibitor.

The glycoprotein cow colostrum trypsin inhibitor was investigated by high resolution 1H nuclear magnetic resonance (NMR) at 360 MHz and, on the basis of the NMR data, compared with the basic pancreatic trypsin inhibitor (Kunitz) from bovine tissue. Detailed studies of the chemical shifts and the exchange kinetics of the labile protons indicated extensive homologies between the spatial structures of the polypeptide chains in the two compounds. This was further corroborated by comparison of the NMR spectral features and the dynamic properties of the aromatic amino acid residues in the two inhibitors. It thus appears that the covalently attached carbohydrate moiety in the colostrum inhibitor has only very limited effects on the spatial structure of the protein part of the molecule. On the other hand, as evidenced by the NMR line widths, the carbohydrate attachment causes a pronounced restriction of the overall mobility of the molecule, indicating a sizeable increase of the average radius of gyration as compared to the basic pancreatic trypsin inhibitor. Possible spatial arrangements of the globular polypeptide and the carbohydrate moieties in the colostrum inhibitor, which would be compatible with the experimental observations, are discussed.

Amino Acid Sequence↗
PubMed1978

In vitro and in vivo studies with BL-S786, cefoxitin, and cefamandole.

The in vitro antimicrobial activities of BL-S786, cefoxitin, and cefamandole against 90 isolates of Enterobacteriaceae, including Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae and E. aerogenes, were studied by using an agar dilution procedure. Comparison of geometric mean minimal inhibitory concentrations showed that BL-S786 was half as active as cefamandole against Enterobacter species, 2 to 4 times more active than cefamandole against all other species, and 4 to 25 times more active than cefoxitin against all species. In vivo experiments employed acute protection tests in infected mice, using five isolates each of the five genera. Drugs were administered intramuscularly in two doses 3 h apart at dosages of 2.5, 5, 10, 20, and 40 mg per mouse. In most instances, BL-S786 was the most efficacious drug, being some 1.3 to 9.1 times more active than cefoxitin in all experiments and 1.5 to 8.7 times more active than cefamandole in most experiments. BL-S786 and cefamandole were comparable in activity in experiments with E. aerogenes, whereas BL-S786 was superior in experiments with E. cloacae.

Animals↗
PubMed1978

Effects of metals on heme biosynthesis and metabolism.

Studying the mechanism of interaction of metals with enzymes of the heme biosynthetic pathway has revealed a great deal of understanding of the regulation of the pathway and a possible insight into the toxicology of certain metals. Both positive and negative effects of metals on heme biosynthesis and catabolism can be demonstrated. The understanding of these interactions has given us a clearer picture of certain of the descriptive events known to occur in toxic states induced by these metals. Unfortunately, the studies have also driven us to appreciate the even more complex nature of the biosynthetic and metabolic pathways for heme than was originally hypothesized. It can be predicted that the next 5 years should lead to many more revelations and potential treatment modalities for toxic states induced by metals or genetic diseases where heme biosynthesis does not occur normally.

5-Aminolevulinate Synthetase↗