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Biomedical subjects

T Yoshimura

Publications and source records attributed to T Yoshimura.

At least 775 records · Page 43Linked to original sources
PubMed1982

Stereochemistry of proton abstraction catalyzed by lysine and ornithine omega-aminotransferases.

(6R)-L-[6-3H]Lysine and (6S)-L-[6]3H]lysine were prepared to investigate the stereochemical aspects of the reaction catalyzed by bacterial L-lysine epsilon-aminotransferase. When (6R)-L-[6-3H]lysine was used as a substrate, the tritium label was retained in the product, delta 1-piperideine-6-carboxylate. In contrast, the radioactivity from (6S)-L-[6-3H]lysine was found in the solvent. Thus, the pro-S hydrogen at the prochiral C-6 carbon of L-lysine is specifically abstracted by L-lysine epsilon-aminotransferase. The proton exchange was observed by proton nuclear magnetic resonance analysis in the reaction of bacterial L-ornithine delta-aminotransferase with L-ornithine in 2H2O. The isolated L-[5-2H]ornithine was converted to dextrorotatory 4-phthalimido[4-2H]butyrate. This indicates that L-ornithine delta-aminotransferase catalyzes the stereospecific exchange of the pro-S hydrogen at the prochiral C-5 carbon of L-ornithine with the solvent.

Binding Sites↗
PubMed1982

Prevalence and incidence of onchocerciasis as baseline data for evaluation of vector control in San Vicente Pacaya, Guatemala.

The aim of this study was to estimate the incidence rate of onchocerciasis as measured by skin biopsy during field surveys carried out in San Vicente Pacaya, Guatemala from 1977 through 1979. The age standardized prevalence rates for males and females were 44.6% and 19.9%, respectively, in 1979. There were annual incidence rates of 0.08 and 0.04 for males and females, respectively. The incidence rates seem to increase with age. Since the effect of false negatives will be greater in females than in males, these rates should be interpreted cautiously. Extremely high reversion rates (proportion of negatives in a later examination among positives at the first examination by skin biopsy) were observed; these figures might be explained mainly by false negatives due to the skin biopsy. However, it is suspected that some of the apparent reversion rates may also have been influenced by other factors, e.g., sex difference.

Adolescent↗
PubMed1982

Multivariate analysis using a linear discriminant function for predicting the prognosis of congestive heart failure.

Some of cases of congestive heart failure (CHF) are intractable or refractory and respond poorly to conventional treatment. We have examined factors which may influence the clinical course and prognosis. The subjects were 114 hospitalized patients with CHF. Of these, 77 had a good response to treatment and were classified as the curative group (Group C) while the remaining 37 who were difficult to treat, including those with poor prognosis, were designated the refractory group (Group R). Of the various clinical background factors including the findings of laboratory and other examinations, the following 8 variables made a significant contribution to differentiation between the 2 groups: 1) heart rate (X1), 2) hemoglobin content (X2), 3) serum K (X3), 4) serum total protein (X4), 5) A/G (X5), 6) BUN (X6), 7) grade of hepatomegaly (X7), and 8) number of previous CHF episodes (X8). The linear discriminant function represented by the following equation using these 8 variables showed an excellent result in differentiating the 2 groups. Y = - 9.64 - 0.0686X1 + 0.345X2 + 1.351X3 + 1.513X4 + + 1.988X5 - 0.0876X6 - 0.792X7 - 0.737X8. When Y value is over 0, Group C is judged. When Y value is under 0, group R is judged. We concluded that the discriminant equation covering these 8 factors is a useful means of predicting the prognosis in CHF and the response to treatment.

Adult↗
PubMed1982

Structures of ATP(adenosine triphosphate)-vanadyl complexes.

The state of existence of cytoplasmic vanadium ion is known to be important: vanadyl ion forms complexes with ATP and vanadate form inhibits (Na++K+)-ATPase. Therefore, the formation of complexes between ATP and vanadyl ion was investigated. Formations of three types of complex were observed: a blue 1:1 complex formed in acidic pH region; a blue 1:1 complex formed in neutral pH region; a green 2:1 complex formed in alkaline pH region. On the basis of the results on potentiometric titration, optical and EPR spectra and 31P- and 13C-NMR spectra, three characteristic types of coordination environment are proposed.

Adenosine Triphosphate↗
PubMed1981

Electron transfer between horse heart and Candida krusei cytochromes c in the free and bound states.

Electron transfer between horse heart and Candida krusei cytochromes c in the free and phosvitin-bound states was examined by difference spectrum and stopped-flow methods. The difference spectra in the wavelength range of 540-560 nm demonstrated that electrons are exchangeable between the cytochromes c of the two species. The equilibrium constants of the electron transfer reaction for the free and phosvitin-bound forms, estimated from these difference spectra, were close to unity at 20 degrees C in 20 mM Tris-HCl buffer (pH 7.4). The electron transfer rate for free cytochrome c was (2-3).10(4) M-1.s-1 under the same conditions. The transfer rate for the bound form increased with increase in the binding ratio at ratios below half the maximum, and was almost constant at higher ratios up to the maximum. The maximum electron exchange rate was about 2.10(6) M-1.s-1, which is 60-70 times that for the free form at a given concentration of cytochrome c. The activation energy of the reaction for the bound cytochrome c was equal to that for the free form, being about 10 kcal/mol. The dependence of the exchange rate on temperature, cytochrome c concentration and solvent viscosity suggests that enhancement of the electron transfer rate between cytochromes c on binding to phosvitin is due to increase in the collision frequency between cytochromes c concentrated on the phosvitin molecule.

Animals↗
PubMed1981

A new method for the preparation of acyl-CoA thioesters.

A method is described for the preparation of CoA thioesters of fatty acids. Acyl-CoA thioester was synthesized by way of 1-acylimidazole and purified by high performance liquid chromatography. This method is applicable to the preparation of a variety of acyl-CoA thioesters of various chain lengths (from C2 to C18) and with varying degrees of unsaturation. It is particularly suitable for preparing acyl-CoA thioesters of labeled fatty acids or fatty acids available only in small amounts.

Acyl Coenzyme A↗