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Biomedical subjects

T Mitsui

Publications and source records attributed to T Mitsui.

At least 307 records · Page 17Linked to original sources
PubMed1988

A self-induced translation model of myosin head motion along thin filament in muscle contraction.

Evidence has been accumulating that muscle contraction may not be associated with the power stroke of the cross-bridges tightly coupled with ATP hydrolysis cycle. We have constructed a new contraction model which includes a number of basic properties of contraction processes not taken into consideration in the models hitherto reported. The basic assumption is that, when one head of a myosin molecule attaches to an actin monomer on thin filament, conformational changes take place in the neighbouring actin monomers to result in their non-symmetrical charge distribution to exert electrostatic force on the unattached head of the same myosin molecule in one direction. Thus, the unattached head moves along thin filament to attach to another actin monomer, while the already attached head detaches from thin filament. These steps are repeated to cause muscle contraction. The above contraction model can explain the results of our X-ray diffraction experiments as well as the results reported by other authors.

Actin Cytoskeleton↗
PubMed1988

Antibody against the translation product of the pre-S2 region of hepatitis B virus and the resolution of infection after accidental needlestick exposure.

During a 5-yr period before the introduction of post-exposure immunoprophylaxis of hepatitis B virus (HBV), 363 medical personnel contracted infection after exposure to a contaminated needlestick. Among them, five (1.4%) developed a persistent carrier state, and they were followed for antibodies against translation product of the pre-S2 region (anti-pre-S2) by the enzyme immunoassay with native viral polypeptides. The consecutive seven cases in whom infection was terminated served as controls. In the acute phase, the levels of IgM and IgG anti-pre-S2 were significantly higher in the seven in whom infection resolved than in the five in whom infection persisted (mean sample:normal ratio, 11.1 +/- 4.4 vs 2.0 +/- 1.3 and 8.7 +/- 7.0 vs 3.0 +/- 1.1, respectively, p less than 0.05). In convalescence, 6 months after the normalization of serum transaminase, IgG anti-pre-S2 was detected in a high titer in the staff members with resolved infection (27.4 +/- 38.5), but was not detectable in those with persistent infection. On the basis of these observations, the intensity of humoral antibody response against the pre-S2 region product is closely correlated with the resolution of infection after exposure to HBV, and anti-pre-S2 persists in the circulation much longer than previously reported.

Accidents, Occupational↗
PubMed1987

Differential changes in atrial natriuretic peptide and vasopressin receptor bindings in kidney of spontaneously hypertensive rat.

To elucidate the role of atrial natriuretic peptide (ANP) and vasopressin (VP) in a hypertensive state, ANP and VP receptor bindings in spontaneously hypertensive rat (SHR) kidney were analyzed using the radiolabeled receptor assay (RRA) technique. Systolic blood pressure of SHR aged 12 weeks was statistically higher than that of age-matched Wistar Kyoto (WKY) rats. Maximum binding capacity (Bmax) of [125I]-ANP binding to the SHR kidney membrane preparations was statistically lower than that of WKY rats, but dissociation constant (Kd) was not significantly different. On the other hand, Bmax of [3H]-VP binding to the SHR kidney membrane preparations was statistically higher than that of WKY rats, but Kd were similar. Since the physiological action of ANP is natriuresis and VP is the most important antidiuretic hormone in mammalia, these opposite changes of ANP and VP receptor bindings in SHR kidney suggested that these peptides may play an important role in the pathophysiology of the hypertensive state, although it has not been confirmed as yet.

Animals↗
PubMed1987

[Risk factors influencing the prognosis of severe aortic valve disease following aortic valve replacement].

As a result of improvement in intraoperative and postoperative management, severe aortic valve disease can be cured by operation, however, late cardiogenic sudden death after aortic valve replacement (AVR) has been existed as one of the important unsolved problem. This report is aimed to predict the risk factors influencing the postoperative prognosis of severe aortic valve disease. Twenty-three cases with aortic regurgitation (AR) and 20 cases with aortic stenosis (AS) were selected by postoperative period over 12 months. In 18 AR cases with normal coronary artery substantiated by selective coronary angiography, cross sectional area index of left ventricular wall (CSAI) and ST depression in left chest leads of electrocardiogram correlated well as the CSAI increased, so decreased the ST segment. This shows the increment of CSAI leads left ventricular endocardial ischemia. By means of introduction of this indicator, 23 AR and 20 AS patients were divided into two groups as group C-I having CSAI over 20 cm2/m2 and group C-II under 20 cm2/m2. Left ventricular ejection fraction (EF) was selected as an predictive indicator of left ventricular function. As same as CSAI, AVR cases were divided into two groups as group E-I having EF under 50% and E-II over 50%. Each group was compared concerning with the complication rate of postoperative low cardiac output syndrome (LOS) and late cardiogenic sudden death. In C-I group of AR, 55% cases accompanied with LOS, 18% died due to LOS and 18% died suddenly from late cardiogenic cause, however, none of cases in C-II group had these complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗