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Biomedical subjects

R A Klein

Publications and source records attributed to R A Klein.

At least 73 records · Page 4Linked to original sources
PubMed1979

A new series of long-chain dicarboxylic acids with vicinal dimethyl branching found as major components of the lipids of Butyrivibrio spp.

1. Some members of the genus Butyrivibrio, including a general fatty acid auxotroph (strain S2), contain as a major part of their complex lipids a high-molecular-weight component that is probably formed by the union of two fatty acid chains [Hazlewood & Dawson (1979) J. Gen. Microbiol. 112, 15--27]. 2. Proton and 13C n.m.r. and i.r. and mass spectroscopy were used to examine a homologous series of these moieties and, in addition, the hydrocarbon derivative of one homologue and several synthetic compounds. 3. The results indicate that the high-molecular-weight components are a series of long-chain dicarboxylic acids containing vicinal dimethyl branching, located near the centre of the chain.

Chemical Phenomena↗
PubMed1978

Synergy studies with Pseudomonas aeruginosa resistant to gentamicin and/or carbenicillin.

The predictability of synergy with strains of Pseudomonas aeruginosa highly resistant to gentamicin in combination with carbenicillin has been controversial. 30 clinical isolates of P. aeruginosa resistant to gentamicin and/or carbenicillin were tested by checker-board technique. 14 were found to be highly resistant to gentamicin (minimal inhibitory concentration MIC greater than or equal to 128 microgram/ml) and/or carbenicillin (MIC greater than or equal to 512 microgram/ml). Of these 14, 4 isolates showed synergy. 10 of 16 isolates with moderate resistance demonstrated synergy. It is concluded that the level of resistance to gentamicin with P. aeruginosa cannot be used in predicting whether synergy will occur.

Carbenicillin↗
PubMed1977

Doxycycline in abdominal surgery.

Twenty patients undergoing urgent or emergency surgical procedures where intra-abdominal infection was suspected were treated with doxycycline hyclate. Wound infections involving anaerobic, aerobic, or facultative bacteria developed in four of 11 patients treated with doxycycline alone. Nine other patients received higher doses of doxycycline plus gentamicin sulfate. Five of these had postoperative infections primarily involving anaerobic organisms. Bacteremia with a doxycycline-resistant Bacteroides fragilis developed in one patient during therapy. Serum levels of doxycycline, even at the higher dosage, were below the minimal inhibitory concentrations (MICs) of a number of potential pathogens isolated at the time of surgery. Doxycycline is not indicated in cases of serious intra-abdominal infection unless the infecting flora are known to be susceptible.

Abdomen↗
PubMed1977

Threonine catabolism in Trypanosoma brucei.

L-Threonine is catabolized by Trypanosoma brucei to give equimolar quantities of glycine and acetate. The pathway, which involves the two enzymes L-threonine dehydrogenase (EC 1.1.1.103) and aminoacetone synthase (acetyl-CoA:glycine C-acetyltransferase, EC 2.3.1.29) and subsequent hydrolysis of the acetyl-CoA, is most active in cultured trypanosomes but is also present in bloodstream forms. L-Threonine dehydrogenase from both culture and bloodstream forms of trypanosomes has an apparent molecular weight of between 28 000 and 38 000, and is sensitive to a wide range of sulphydryl reagents.

Acetone↗
PubMed1975

Utilization of amino acids by Trypanosoma brucei in culture: L-threonine as a precursor for acetate.

The amino acid compositions of several culture media have been analysed and compared. The utilization and excretion of amino acids and other metabolites have been followed during growth of Trypanosoma brucei S42 in a defined medium. All of the added L-threonine was metabolized by the cells, even when it was present at elevated concentrations. Glucose was consumed throughout the growth cycle: glutamine was consumed more rapidly than glutamic acid, which was itself used at about the same rate as proline. Threonine was cleaved to form glycine and acetate, both of which accumulated in the medium. Alanine and succinate were excreted together with a small amount of pyruvate, but these three products accounted for less than half of the glucose used. CO2 production from glucose was not measured, but insignificant amounts of CO2 were produced from threonine. Tetraethylthiuram disulphide blocked the cleavage of threonine and was a potent inhibitor of trypanosome growth.

Acetates↗
PubMed1975

Carbon dioxide fixation in trypanosomatids.

Fixation of carbon dioxide has been demonstrated for extracts from Crithidia fasciculata, Trypanosoma mega and Trypanosoma brucei brucei bloodstream and culture forms. The enzymes involved in this fixation were found to be ADP-stimulated phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32), 'malic' enzyme (E.C. 1.1.138-40) and pyruvate carboxylase (E.C. 6.4.1.1). The subcellular localization of these enzymes has been investigated in all three organisms. Products of short and long term fixation experiments were separated and identified. The importance of carboxylation reactions is discussed in relation to the maintenance of oxidized and reduced coenzyme levels.

Bicarbonates↗