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Biomedical subjects

R A Klein

Publications and source records attributed to R A Klein.

At least 55 records · Page 3Linked to original sources
PubMed1983

Bromoacetyl-L-carnitine: biochemical and antitrypanosomal actions against Trypanosoma brucei brucei.

One of the causative agents of the African Trypanosamiases, Trypanosoma brucei brucei is able to use high intracellular carnitine concentrations and a high carnitine acetyl transferase (CAT) activity to stimulate ATP production. This paper reports that a carnitine analogue, bromoacetyl-L-carnitine, is an irreversible inhibitor of CAT from T.brucei, non-competitively inhibits carnitine uptake by T.brucei and has a potent in vitro effect against T.brucei motility and infectivity. An in vivo action in T.brucei infected mice is also reported. These results represent a new area of investigation in the important search for new antitrypanosomal agents.

Acetylcarnitine↗
PubMed1983

The analysis of fatty acid binding to protein using a modified equilibrium dialysis method: detailed analysis of chromophore-fatty acid-protein interactions.

In this paper we extend our previous analysis of fatty acid-chromophore-protein interactions using a modified equilibrium dialysis method described previously. A more rigorous mathematical treatment is combined with a micro-dialysis method using a maximum volume of dialyzate of between 250 microliters and 400 microliters to examine the suitability of different chromophores (mepacrine, quinine, chloroquine, chlorpromazine, methylene blue, rhodamine 6G, 6-carboxyfluorescein) for studying the binding of fatty acid to protein. The macro- and micro-methods of dialysis are compared, and the binding of fatty acid to bovine serum albumin and beta-lactoglobulin discussed as examples of the method. Problems associated with propagated errors in the measurements and obtaining the number of binding sites and the binding constants from curve-fitting are also considered.

Binding Sites↗
PubMed1983

Disseminated Strongyloides stercoralis: a fatal case eluding diagnosis.

We have described a patient who died of disseminated strongyloidiasis as a result of steroid therapy, despite an extensive diagnostic evaluation in the face of eosinophilia, but before any immunosuppressive therapy. This death might have been prevented by presumptive treatment after work-up but before immunosuppressive therapy, and repeat diagnostic evaluation after antistrongyloides therapy and during immunosuppressive therapy.

Combined Modality Therapy↗
PubMed1983

Massive hepatic hemorrhage associated with cardiopulmonary resuscitation.

We treated two patients with laceration of the liver that was precipitated by cardiopulmonary resuscitation (CPR) and recognized antemortem. Both patients had myocardial infarctions and had received heparin sodium therapy. They had excruciating abdominal pain and bled massively, resulting in hypovolemic shock. When severe abdominal pain associated with hypovolemic shock occurs in a patient who has received CPR, hepatic laceration, hematoma, or both should be considered. This is even more imperative to recognize in the patient who has received anticoagulation therapy.

Female↗
PubMed1982

The substructure of phosphodiesterase as established by radiation inactivation. A reinterpretation of results.

A model for the activation of phosphodiesterase by calmodulin based on a conversion of inactive dimers to active monomers, derived from radiation inactivation studies J. Biol. Chem. (1981) 256, 11351-11355 has been re-examined using a simple probability argument. We conclude that the original model is not supported by the radiation inactivation studies, since our analysis of this model would predict that the rate of radiation inactivation of calmodulin-dependent phosphodiesterase activity be exactly twice that for the decay in total activity in marked contrast with the results obtained.

Calcium-Binding Proteins↗
PubMed1982

Pressure and temperature effects on human red cell cation transport.

The effects of hydrostatic pressure and temperature on the three components of K+ uptake in human red cells have been investigated, using ouabain and bumetanide to distinguish between the pump, passive diffusion and cotransport. The pressure sensitivity for passive diffusion has been shown to depend on the counter-ion present. The order of this effect, Cl- greater than Br- greater than NO3- greater than I-, is the same as for the ionic partial molal volumes and the Hofmeister series. We have analyzed our experimental results thermodynamically, and propose a model for the activated transition-state complex of the potassium ion which involves the loss of water molecules from the secondary hydration shell, cosphere II.

Anions↗
PubMed1982

A modified equilibrium dialysis method for studying fatty acid binding to proteins.

A modified equilibrium dialysis method is described which is suitable for investigating the binding of fatty acids in the form of aqueous micellar dispersions to proteins. The method uses a permeant chromophore which complexes reversibly with free fatty acid within the dialysis bag. The concentration outside the dialysis bag is determined spectrophotometrically. Binding of oleic acid to bovine serum albumin is given as an example. A simplified analysis of fatty acid binding is given and used to indicate the potential of the method.

Animals↗
PubMed1982

Maintaining competency of sterile products personnel.

The literature is replete with articles concerning the importance of properly training and monitoring individuals assigned the responsibility of preparing sterile products. At the William L. Keller U.S. Army Community Hospital, the monitoring of these individuals has taken the form of a monthly examination composed of mathematical and technical functions.

Antisepsis↗
PubMed1980

Increased human red cell cation passive permeability below 12 degrees C.

The rate of most biological reactions declines as the temperature is reduced; indeed, cooling is often used to limit or terminate reactions. We report here a paradoxical temperature response of red cell K and Na permeability below 12 degrees C. This may be interpreted thermodynamically in terms of a membrane-ordering phenomenon, an observation supported by a variety of other physical measurements on red cell membranes reported in the literature.

Anions↗
PubMed1980

The use of 13-methyltetradecanoic acid as an indicator of adipose tissue turnover.

We show in this paper that 13-methyltetradecanoic acid (13-MTD) can be used as a structually labeled marker for investigating the mobility of fatty acyl chains in adipose tissue in the rat. The presence of an omega-1 methyl group allows easy quantitation by gas liquid chromatography (GLC) and permits an assessment to be made of any oxidation and chain elongation reactions with reincorporation of the label into the adipose tissue, since the iso-acyl chain is well resolved from odd or even-numbered homologous fatty acids with straight chains. The kinetics of uptake and loss of the structural label were different for adipose tissue taken from the various sites which were sampled, namely post abdominal, mesenteric, perirenal, pericardiac and subcutaneous adipose tissue as well as the epidydimal fat pads. We also report preliminary results in man which confirm that the method is applicable to human clinical studies and that 13-MTD kinetics differ for adipose tissue taken from the 3 different subcutaneous sites--waist, arm and thigh.

Adipose Tissue↗
PubMed1980

Effects of oligomycin on glucose utilization and calcium transport in African trypanosomes.

Oligomycin (3 microgram ml-1) inhibited glucose utilization in Trypanosoma brucei S42 as shown by measurements of oxygen uptake and pyruvate production. Carbonyl cyanide 3-chlorophenylhydrazone, an uncoupler of oxidative phosphorylation, did not relieve this inhibition, although some relief was afforded by the alternative substrate glycerol. Naturally dyskinetoplastic Trypanosoma evansi MIAG 105 was less sensitive to inhibition by oligomycin although glycerol relief was still observed, relecting the differential sensitivity of the two pathways. With glucose present as the substrate, 45Ca2+ transport was inhibited by oligomycin in T. brucei, but was stimulated in T. evansi. These results are discussed in terms of alternative systems for maintaining cytoplasmic Ca2+ concentrations in normal and dyskinetoplastic strains of trypanosome.

Animals↗