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Biomedical subjects

M Okabe

Publications and source records attributed to M Okabe.

At least 361 records · Page 20Linked to original sources
PubMed1988

Effect of a monoclonal anti-mouse sperm antibody (OBF13) on the interaction of mouse sperm with zona-free mouse and hamster eggs.

Mouse eggs freed from zonae by chymotrypsin were mixed with sperm and pronuclear formation was observed. When anti-mouse sperm monoclonal antibody (OBF 13) from ascites fluid was added to the medium (at a final concentration of 0.05%), fertilization was significantly inhibited (9.7 +/- 4.3% compared to control 56.7 +/- 7.4%, P less than 0.01). This was based on the inhibition of sperm binding to the egg. However, when similar experiments were performed using zona-free hamster eggs, addition of the OBF 13 antibody caused no significant reduction in fertilization rate (91 +/- 7.1% compared to control 97 +/- 3.2%). It was also observed that binding of mouse sperm to hamster eggs was not inhibited by the antibody. It is therefore suggested that mouse sperm and mouse egg recognize each other in a species-specific manner.

Animals↗
PubMed1988

Chromophore/protein and chromophore/anion interactions in halorhodopsin.

Halorhodopsin (HR), the light-driven chloride transport pigment of Halobacterium halobium, was bleached and reconstituted with retinal analogues with the pi electron system interrupted at different locations (dihydroretinals). The absorption maxima of the artificial pigments formed with the dihydroretinals are found to be very similar to those of the corresponding pigments formed by reconstitution of bacteriorhodopsin (BR) and sensory rhodopsin (SR). This strongly suggests that the distribution of charges around the retinal is similar in all three bacterial rhodopsins. Comparison of the primary, and proposed secondary, structures for HR and BR reveal conserved asparagine (asp) and arginine (arg) residues, which are likely candidates for the ionizable amino acids that interact with the retinal. In a second set of experiments absorption shifts due to the binding of anions to Sites I and II in HR, reconstituted with different retinal analogues, were used to estimate the locations of these binding sites relative to the retinal. Site I is localized near the Schiff base, and Site II near the ionone ring. On the basis of these results a structural model for HR is proposed, which accounts for the spectroscopic properties of HR in terms of the three buried arg residues and two of the buried asp residues in the protein.

Bacteriorhodopsins↗
PubMed1988

Danger of use of disopyramide in patients with hypertrophic obstructive cardiomyopathy. An electrophysiologic study.

A 61-year-old man with hypertrophic obstructive cardiomyopathy with asymptomatic ventricular tachycardia underwent electrophysiologic study. Double extrastimuli at the right ventricular outflow tract induced polymorphic ventricular tachycardia which degenerated into fibrillation. After intravenous administration of 50 mg of disopyramide, the pressure gradient in the outflow tract disappeared, but the tachycardia inducing zone appeared at the right ventricular apex. Although disopyramide may be used in patients with hypertrophic cardiomyopathy to relieve the intraventricular pressure gradient, it should be used only after evaluating its safety and efficacy electrophysiologically.

Cardiac Pacing, Artificial↗
PubMed1988

Mutagenesis of OA-6129 carbapenem-producing blocked mutants and the biosynthesis of carbapenems.

Streptomyces fulvoviridis A933 17M9 1501 is an A933 acylase-defective mutant derived from S. fulvoviridis A933 17M9 and thus produces the OA-6129 group of carbapenems and carbapenams. By further mutation of mutant 1501, 4 types of mutants (OA-6129 A + B1 + B2 producers; OA-6129 A + B2 producers; an OA-6129 A producer; non-producers) were obtained. The second type of mutant strains 4N 3607, 5NA 3949-40 and 5NE 252 proved useful for the fermentative production of carbapenem OA-6129 B2. These results of mutagenesis demonstrated that the sequence of carbapenem bioconversion in the horizontal route was hydroxylation at C-8----isomerization at C-6----sulfation at C-8 hydroxyl.

Mutation↗
PubMed1988

[The evaluation of operability for patients with severe valvular disease].

The present study was designed to evaluate and determine the factors which affected the prognosis of the surgical patients with severe valvular diseases. Four hundred and forty six cases which underwent valvular surgery from 1977 to 1987 were used for this study. There were 16 early death cases (3.6%) and 16 late death cases (3.6%), respectively. The early death rate after surgery was significantly high in the cases which had 1) poor LV function (LVEF less than 35%), 2) liver dysfunction (T-Bil greater than 1.3mg/dl, ICG-Rmax less than 1.0 mg/kg/min, Ch-E less than 0.6PH, K-ICG 0.10/min), and/or 3) PVE after valve replacements. These factors were recognized in 9 (56.3%) of the early death cases and 10 (62.5%) of the late death cases. Thus, we consider that these factors affect the surgical prognosis and that the border line values for the factors are: 1) LVEF less than 0.3%, LVDI greater than 40 ml/m2 in MS group and 50 mg/m2 in other valvular groups. 2) T-Bil greater than 2.7 mg/dl, ICG-Rmax less than 0.5mg/kg/min in cardiac cachectic cases, and 3) active PVE cases which showed drug-resistance. Furthermore, these values should be corrected by IVH and immunosupportives during the pre- and post-operative periods.

Adolescent↗
PubMed1987

Properties of recombinant hepatitis B vaccine.

A large-scale purification method for hepatitis B surface antigen produced in a recombinant yeast (Saccharomyces cerevisiae) was established. The resulting HBsAg was greater than 99% pure and suitable for vaccine use. The yeast-derived HBsAg was structurally and biochemically similar to plasma-derived HBsAg. The anti-HBs antibody producing potency of the yeast-derived vaccine in mice was significantly higher than that of the plasma-derived vaccine. The yeast-derived vaccine induced protective antibody against hepatitis B virus of either adr or ayw subtype in a chimpanzee efficacy study. These observations demonstrate the usefulness of the yeast-derived vaccine as a second-generation hepatitis B vaccine.

Amino Acids↗
PubMed1987

Capacitation-related changes in antigen distribution on mouse sperm heads and its relation to fertilization rate in vitro.

The anti-mouse sperm monoclonal antibody OBF13 did not react with fresh epididymal sperm. However, when sperm were incubated in a culture medium capable of inducing capacitation, the entire head of the sperm began to react with this antibody. This change of reactivity was not observed when sperm were incubated in a Ca2+-free medium. The change of the reactivity to the antibody was studied in relation to the fertilizing ability of sperm as measured in an in vitro fertilization system; a significant correlation was observed between the appearance of head-stained sperm and fertilization rate.

Acrosome↗