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Biomedical subjects

L Davis

Publications and source records attributed to L Davis.

At least 271 records · Page 15Linked to original sources
PubMed1977

Management of diabetic patients with low blood pH.

In metabolic acidosis, where blood pH is less than 7.20, loss of respiratory centre response to lowered carbon dioxide content and increased hydrogen ion concentration may result. The use of sodium bicarbonate for management of diabetic ketosis and lactic acidosis has been controversial (Kaye 1975) in the past, but it is now the treatment of choice.

Adult↗
PubMed1976

The oxidation of dithiothreitol by peroxidases and oxygen.

Horseradish peroxidase (1.11.1.7), lactoperoxidase (1.11.1.7), and the fragment of cytochrome c known as microperoxidase have been shown to catalyze the oxidation of reduced dithiothreitol in an oxygen-consuming reaction. Evidence for horseradish peroxidase intermediates compound III and compound II has been observed, although ferroperoxidase was not identified during the course of the reaction. The stoichiometry has been extablished as 1 : 1 for oxygen consumed to dithiothreitol oxidized. Cysteine and glutathione have also been shown to be substrates for horseradish peroxidase oxidase reaction.

Catalase↗
PubMed1976

Stereochemistry of the reaction of sheep liver threonine dehydratase. A nuclear magnetic resonance and optical rotatory dispersion study of its reaction pathway and products.

Products, substrates, and inhibitors of the threonine dehydratase from sheep liver (EC 4.2.1.16) have been investigated by proton nuclear magnetic resonance and optical rotation. The alpha-ketobutyrates produced from L-threonine and L-allothreonine in 2H2O have been shown to incorporate a single deuterium into the beta position. The dehydratase forms R-alpha-ketobutyrate-beta-d from L-threonine and L-allothreonine. The alpha protons of the substrates, threonine and allothreonine, do not exchange in the presence of the dehydratase. In the presence of dehydratase, the competitive inhibitors L-cysteine and L-alanine undergo alpha-proton exchange. Highly purified dehydratase has been used to determine kinetic parameters for the usbstrates L-threonine, L-allothreonine, L-serine, and L-chloroalanine. L-Chloroalanine, in addition to being a substrate, inhibits the dehydratase in a manner kinetically identical with that of L-serine.

Alanine↗
PubMed1976

Experience with internal mammary artery grafts in 298 patients.

The internal mammary artery (IMA) was used as a graft in 298 patients undergoing coronary bypass procedures. Two patients died during the operative period and 2 others died one year later. Most of the survivors are free of angina. Of the IMAs restudied 9 to 24 months postoperatively, 95% were patent. This group included nearly all the patients having angina after operation. There are some situations in which the IMA may have inadequate flow in comparison to the vein graft. These results suggest the IMA is an excellent graft in most coronary bypass procedures.

Adult↗
PubMed1976

Community resources--why should we use them.

Professionals working with low vision persons may find themselves in the situation where they are either the first or only contact known to their patient. Because one person is usually not able to fulfill the diverse needs of the visually impaired individual, he may find it necessary to refer patients to other sources. Knowledge of the role of other related professionals and their availability in the community may make the difference between a fragmetned receipt of services or a total approach to vision rehabilitation.

Adult↗
PubMed1976

Aspects of the teratology of cyclophosphamide (NSC-26271).

Wistar-derived rat embryos were most sensitive to maternally administered cyclophosphamide on Days 9.5 and 10.5 of gestation and to chlorambucil on Day 9.5 of gestation. The spectrum of malformations and the dose-response behavior of both drugs were similar. Chlorambucil was three times more potent than cyclophosphamide on an mg/kg basis. The drugs showed additive behavior when administered in combination. The teratogenic effects of the individual or combined drugs were reduced by protective doses of cysteine or glutathione. Studies with analogs of cyclophosphamide have suggested that the whole molecule is involved in teratogenesis.

Abnormalities, Drug-Induced↗
PubMed1976

[Pharmacological influence on central serotonergic mechanisms in man and its consequences on sleep (author's transl)].

Central serotonergic mechanisms were investigated in three experiments: 1. Chronic administration (four weeks) of L-5-hydroxytryptophan (L-5 HTP 600 mg/day) plus decarboxylase inhibitor (Ro 4-4602) reduces slow-wave sleep (stages 3 + 4 = SWS) without influencing other sleep parameters. 2. Clozapine reduces SWS, increases paradoxical sleep (REM) and dissociates sleep mechanisms so that increased REM in NREM stage 1 occurs. Central serotonin levels seem to remain unaffected. 3. Parachlormethylamphetamine, a serotonin synthesis inhibitor, normalises irregular sleep and narcoleptic and cataleptic attacks of narcoleptic syndrome as well. 4. Central serotonergic mechanisms are described as having a boundary-setting function.

5-Hydroxytryptophan↗
PubMed1975

Sheep liver serine-threonine dehydratase. I. Purification and evidence for covalently linked alpha-ketobutyrate as its cofactor.

L-Serine-threonine dehydratase (EC 4.2.1.16) from sheep liver has been obtained as a highly purified preparation as shown by ultracentrifuge studies and analytical disc gel electrophoresis. The dehydratase has a molecular weight of 98,000 +/- 10,000 and is composed of two nonidentical subunits with molecular weights of 41,000 and 47,000. The 41,000 subunit is covalently linked to the carbonyl reagent-sensitive coenzyme which has been identified as alpha-ketobutyric acid.

Animals↗
PubMed1975

An investigation of the role of the copper in galactose oxidase.

Galactose oxidase is a metalloenzyme containing a single copper atom per molecule. The mechanism of action of galactose oxidase is studied in this paper by investigating substrate specificity and activation by peroxidase, and probing the copper site by electron spin resonance (ESR) spectroscopy. Line-shape simulation of ESR spectra are also reported and a comparison is made between observed and simulated spectra for galactose oxidase. A comparison is also reported for the enzyme from various commercial sources and enzyme isolated from a fungus in this laboratory. The results of this investigation suggest that the copper is in an environment of four in-plane nitrogens with axial symmetry.

Alcohol Oxidoreductases↗