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Biomedical subjects

T Sakurai

Publications and source records attributed to T Sakurai.

At least 829 records · Page 46Linked to original sources
PubMed1981

Multiple nutritional requirements of lactobacilli: genetic lesions affecting amino acid biosynthetic pathways.

Genetic lesions responsible for amino acid requirements in several species of multiple auxotrophic lactobacilli were investigated. Systematic attempts were made to isolate mutants that could grow in the absence of each of the amino acids required by the parental strains of Lactobacillus plantarum, L. casei, L. helveticus, and L. acidophilus. After treatment with appropriate mutagens, such mutants could be obtained with respect to many but not all required amino acids. Successful isolation of mutants for a given amino acid means that a minor genetic lesion reparable by single-step mutations affects its biosynthesis; a failure to isolate mutants suggests the involvement of more extensive lesions. Analysis of these results as well as the specific requirements exhibited by the parental strains revealed certain regularities; some of the biosynthetic pathways for individual amino acids were virtually unaffected by more extensive lesions in at least species tested, whereas others were affected by more extensive lesions in at least some species. Both the number and the kind of pathways affected by extensive lesions differed appreciably among different species. Furthermore, the growth response of the parental strains to some putative amino acid precursors revealed a clear correlation between the extent of genetic lesions and the occurrence and location of a genetic block(s) for a given pathway. These findings are discussed in relation to the phylogeny, ecology, and evolution of lactic acid bacteria.

Amino Acids↗
PubMed1981

Effects of phenylbutazone and mefenamic acid on two classes of binding sites of 2-(4'-hydroxyphenylazo)benzoic acid on bovine serum albumin characterized by absorption spectra and circular dichroism spectra.

The competitive binding of phenylbutazone (PB) and mefenamic acid (MF) with 2-(4'-hydroxyphenylazo)benzoic acid (HABA) on bovine serum albumin (BSA) was studied by the investigation of the effects of these drugs on two bound forms of HABA, the azo and hydrazone forms. PB displaced preferentially the hydrazone form. MF displaced both the azo and hydrazone forms, though the azo form was preferentially displaced at the small molar ratio of MF to BSA. The binding constants of PB and MF obtained from the convenient spectrophotometry were dependent on the concentration of added drugs. These facts reflect the selective displacement of the azo and hydrazone forms. In connection with the absorption spectra of bound HABA, induced circular dichroism (CD) spectra of HABA-BSA complex were investigated. The induced CD spectra varied with the change of the molar ratio of HABA to BSA, indicating the presence of at least three different perturbed HABA molecules by BSA. The addition of PB and MF caused dramatic changes of the induced CD spectra of HABA-BSA complex. These spectral changes were discussed with the displacement of the azo and hydrazone forms.

Azo Compounds↗
PubMed1981

Assignment of circular dichroism spectra of 2-(4'-hydroxyphenylazo)benzoic acid induced by bovine serum albumin to the azo form.

In the displacement study, the effects of tolbutamide on the absorption spectra and induced CD spectra of 2-(4'-hydroxyphenylazo)benzoic acid(HABA)-bovine serum albumin (BSA) complex were investigated using the samples obtained from equilibrium dialysis at pH 7.40. The binding of tolbutamide to BSA enhanced the binding of the azo form in spite of the displacement of the hydrazone form of bound HABA at the molar ratio of HABA to BSA of 0.65, causing the increase in the negative ellipticity at 445 nm, which was termed the C band. The C band could be assigned to the azo form of bound HABA.

Animals↗
PubMed1981

Binding of 2-(4'-hydroxyphenylazo)benzoic acid to bovine serum albumin characterized by optical spectroscopy and equilibrium dialysis.

Binding of 2-(4'-hydroxyphenylazo)benzoic acid (HABA) to bovine serum albumin (BSA) was studied by equilibrium dialysis, by the spectrophotometric method and by the absorption spectra of bound HABA. Comparison of equilibrium dialysis with the spectrophotometric method clarified the presence of a undisclosed class of binding sites, which do not cause the spectral change at about 480 nm to HABA, on BSA. Two bands observed on the absorption spectra of bound HABA were attributed to differently perturbed two HABA molecules by BSA, the azo and hydrazone forms, and these two forms correspond to HABA molecules bound to non-metachromasy sites and metachromasy sites, respectively. The concentration of each from was calculated by using estimated molar extinction coefficient.

Animals↗
PubMed1981

Pulsatile venous flow in extracorporeal circulation.

Effects of pulsatile venous flow upon the microcirculation were investigated in conditions with different venous pressures by using regional perfusion in dog's hind legs. In animals with venous pressure of -18 cmH2O (Collapsed stage), venous pulsation brought about a significant increase in mean oxygen consumption ratio and suppressed a rise of mean resistance ratio significantly. In animals with venous pressure of +2 cmH2O (normal venous pressure stage), the venous pulsation was effective in a rise of mean oxygen consumption ratio but was not effective in suppression of mean resistance ratio. In animals with venous pressure of +10 cmH2O (congestive stage), no effect of venous pulsation was recognized. We suppose that the intermittent elevation of venous pressure by venous pulsation is effective for opening some capillaries in animals with venous pressure below +2 cmH2O.

Animals↗
PubMed1981

The effects of administration of semicarbazide and aminooxyacetic acid on B6 vitamer levels in subcellular fractions of mouse brain.

The in vivo effects of semicarbazide (SC) and aminooxyacetic acid (AOAA) on the B6 vitamer concentrations in brain subcellular fractions, especially in extrasynaptosomal, synaptosomal plasma, extrasynaptosomal and synaptosomal mitochondria, were investigated. Treatment of mice with SC decreased levels of pyridoxal phosphate (PLP) in extrasynaptosomal and synaptosomal plasma, while it had no effect on those in extrasynaptosomal and synaptosomal mitochondria. On the contrary, treatment with AOAA more significantly decreased pyridoxamine phosphate (PMP) levels in extrasynaptosomal and synaptosomal mitochondria than those in extrasynaptosomal and synaptosomal plasma. According to these results, the difference between in vivo effects of SC and AOAA on vitamin B6-enzymes was discussed.

Acetates↗
PubMed1981

[Studies of vesico-urethral function by urethral pressure profile during drug treatment (author's transl)].

The urethral closure pressure profile (UPP) examination was performed routinely together with the administration of alpha-blockers. By the measurement of UPP, we can understand whether the organic changes at the bladder neck have already occurred or not. Further, by calculating the decreasing rate of the pressure at the bladder neck (BNP) and the maximum urethral closure pressure (MP), we can determine which nerve component is affected. Particularly, when we want to detect the affected nerve component in a mild disorder of vesico-urethral function, the measurement of UPP is quite useful as one of the screening urodynamic tests.

Adrenergic alpha-Antagonists↗
PubMed1981

In vivo distribution of 14C-labeled N4-behenoyl-1-beta-D-arabinofuranosylcytosine in mice.

In order to clarify the pharmacological characteristics of N4-behenoyl-1-beta-d-arabinofuranosylcytosine (BHAC) and 1-beta-D-arabinofuranosylcytosine (AraC) with regard to their distribution in vivo, 14C-labeled BHAC and 13C-labeled AraC were injected intravenously into mice. Their in vivo distribution was determined by whole-body macroautoradiography and by an oxidation method. The disappearance rates of BHAC[cytosine-2-14C] and BHAC[behenoyl-l-14C] from the blood were slower than that of AraC[cytosine-2-14C], and the elimination rates of BHAC[cytosine-2-14C] and BHAC[behenoyl-14C] into the urine and feces were also slower than that of AraC[cytosine-2-14C]. The total amounts of BHAC[cytosine-2-14C] and BHAC[behenoyl-1-14C] eliminated within 48 hr after the injection were small. AraC[cytosine-2-14C] was equally distributed in each organ, while large amounts of BHAC[cytosine-2-14C] were found in and the placentae. The BHAC[behenoyl-1-14C]level in the thymus was lower than that of BHAC[cytosine-2-14C]. A very low level of radioactivity was found in most of the organs 6 hr after the injection of Arac[cytosine-2-14C], but BHAC[cytosine-2-14C] was observed even 24 hr after the injection. Radioactivity was still found in the liver, spleen, kidneys and adrenal glands of mice injected with BHAC[behenoyl-1-14C] even after 72 hr. In pregnant mice, AraC]cytosine-2-14C] was transmitted to the fetuses, but only a very small amount of 14C-BHAC was transmitted to the fetuses.

Animals↗