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Biomedical subjects

J Hayashi

Publications and source records attributed to J Hayashi.

At least 397 records · Page 22Linked to original sources
PubMed1988

Attenuated cardiovascular and sympathetic nerve responses to aortic nerve stimulation in DOCA-salt hypertensive rats.

In order to verify, whether baroreflex sensitivity is changed centrally in DOCA-salt hypertension, the left aortic depressor nerve (ADN) was electrically stimulated in DOCA-salt hypertensive rats. After 3 weeks, tail-cuff systolic pressure was significantly higher in DOCA-salt treated rats than in untreated rats (169 +/- 4 versus 130 +/- 4 mmHg, respectively; P less than 0.001). After cutting both ADN and the carotid sinus nerves, the central cut end of the left ADN was electrically stimulated and frequency dependent depressor, bradycardic and sympatho-inhibitory responses were elicited in both control and DOCA-salt hypertensive rats. However, these responses were significantly smaller in DOCA-salt hypertensive rats than in normotensive controls. Bradycardic and sympatho-inhibitory responses to i.v. injection of norepinephrine were also blunted in DOCA-salt hypertensive rats. These findings suggest that baroreflexes were centrally attenuated in DOCA-salt hypertensive rats and possibly contribute to overall baroreflex attenuation.

Animals↗
PubMed1988

Salt increases blood pressure with biphasic changes in hypothalamic responsiveness in rats.

Tail-cuff systolic pressures became elevated in male Wistar rats fed chow containing 8% NaCl for 4 weeks. After 4 weeks of salt loading, pressor and sympathetic responses to ventromedial hypothalamic stimulation were larger in salt-loaded rats. When similar experiments were done following sinoaortic denervation, all of the effects previously induced by dietary salt loading persisted. By contrast, after only 1 week of salt loading, pressor and sympathetic responses to hypothalamic stimulation were reduced, instead of being increased. Since circulating plasma volume was increased in week 1, it was considered possible that reduced hypothalamic responsiveness was due to enhanced cardiopulmonary baroreflexes. Supporting this interpretation, bilateral vagotomy reversed the hypothalamic inhibition occurring in week 1. Although neither the site nor mechanism causing sympathetic hyperactivity has been determined, our results indicate that chronic dietary salt loading has biphasic effects on the ventromedial hypothalamus: an initial inhibition in the first week followed by stimulation thereafter. These results could mean that dietary salt loading eventually increases sympathetic activity and thereby induces hypertension by stimulating the ventromedial hypothalamus.

Animals↗
PubMed1988

Sex- and age-specific prevalences of HBeAg and anti-HBe among HBsAg carriers with or without liver function abnormalities in Okinawa, Japan.

We investigated sex- and age-specific prevalences of hepatitis B e antigen (HBeAg) and antibody to HBeAg (anti-HBe) in 1,163 carriers of hepatitis B surface antigen (HBsAg) in Okinawa, Japan, and followed them up for longer than one year in correlation with liver function abnormalities. Elevated serum transaminase levels were found in 160 (13.8%) of them. The prevalence of liver function abnormalities was significantly higher in male carriers (127/690, 18.4%) than in female carriers (33/473, 7.0%) at a P value of 0.001. In asymptomatic carriers, the prevalence of HBeAg was 13.2% and that of anti-HBe 80.0%, significantly different from 41.9% and 54.4%, respectively, in carriers with elevated transaminase levels (P less than 0.001). In asymptomatic carriers, the mean age of HBeAg-positive carriers was 16.7 years which was much lower than the 22.8 years in carriers with liver function abnormalities. The prevalence of elevated transaminase levels was significantly higher in carriers with HBeAg than in those with anti-HBe (33.8% vs. 9.7%, P less than 0.001). Based on these results, the prolonged positivity for serum HBeAg would qualify as a predictor for deteriorating liver function among HBsAg carriers.

Adolescent↗
PubMed1988

Prevalence of human immunodeficiency virus (HIV) infection among hemophiliacs in Fukuoka, Japan.

To determine when the hemophiliacs in Fukuoka prefecture, Japan, first became positive for antibodies, we tested human immunodeficiency virus (HIV) antibodies on serum samples obtained from 1976-1987 stored at -30 C. Fifteen out of 64 hemophilia A patients (23.4%), five out of 11 hemophilia B patients (45.5%), but none of 17 patients with von Willebrand's disease (0%) were positive for HIV antibodies. In this series, two with hemophilia A became positive for HIV antibodies for the first time in 1983, and in 1984 another four with hemophilia A and one with hemophilia B became positive.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Seroepidemiologic study of adult T-cell leukemia virus (ATLV) and hepatitis B virus infection in Okinawa, Japan.

A total of 2,283 serum samples were collected from healthy subjects in three islands of the Yaeyama district of Okinawa, Japan. These sera were tested for the presence of hepatitis B surface antigen (HBsAg), for antibody to hepatitis B core antigen (anti-HBc), and for antibody to adult T-cell leukemia-associated antigen (anti-ATLA). Correlation between hepatitis B virus infection and adult T-cell leukemia virus (ATLV) infection was determined by using the prevalence rates for three virus markers. Overall prevalence of HBsAg, anti-HBc and anti-ATLA was 6.5%, 57.4%, and 17.9%, respectively. Age-specific prevalence of anti-HBc and anti-ATLA increased with age, but that of HBsAg did not. Sex-specific prevalence of HBsAg was significantly higher in males than in females, but that of anti-ATLA was significantly higher in females than in males. Statistical analysis revealed that prevalence of anti-ATLA was significantly higher in HBsAg-positive persons and HBsAg-negative/anti-HBc-positive persons than in those negative for HBsAg and anti-HBc. These data suggest that hepatitis B virus-infected persons have a significantly higher chance of adult T-cell leukemia virus infection than those without hepatitis B virus infection in the area studied.

Adolescent↗
PubMed1988

Central attenuation of aortic baroreceptor reflex in prehypertensive DOCA-salt-loaded rats.

To determine whether the arterial baroreceptor reflex can act to oppose the development of hypertension, deoxycorticosterone acetate (DOCA)-salt hypertension was produced in sinoaortic-denervated and sham-operated rats. Systolic blood pressure measured by tail cuff started to increase in both sinoaortic-denervated and sham-operated rats 7 days after DOCA treatment, and the hypertension developed identically in both denervated and sham-operated rats. These findings suggest that the baroreceptor reflex cannot act against the development of hypertension. To determine whether the baroreceptor reflex is attenuated before the development of hypertension, bradycardiac and sympathoinhibitory responses to i.v. injections of norepinephrine were examined. Bradycardic and sympathoinhibitory responses were significantly smaller in DOCA-salt-treated rats in both prehypertensive (5th day after DOCA-salt treatment) and hypertensive stages (21st day after treatment). In urethane-anesthetized DOCA-loaded and control rats on the 5th day after treatment, aortic depressor nerve stimulation elicited frequency-dependent depressor and bradycardic responses accompanied by inhibition of sympathetic nerve activity in both DOCA-loaded and control rats. However, those responses were significantly smaller in DOCA-loaded rats than in control rats. These results suggest that the central component of the baroreceptor reflex mediated by the aortic depressor nerve is impaired before hypertension develops and that this impairment may contribute to the development of hypertension in DOCA-salt-treated rats.

Animals↗
PubMed1988

Biochemical mechanism of release of atrial natriuretic polypeptide.

To define transmembrane and intracellular mechanisms of production and release of atrial natriuretic polypeptide (ANP) in the absence of mechanical atrial stretch, we studied the direct effects of physiological stimuli on isolated adult rat atrial myocytes maintained under tissue culture. Although stimulation of beta-adrenergic receptors on the surface of atrial myocytes by isoproterenol did not affect ANP release, adrenergic alpha-1 receptor stimulation by methoxamine enhanced ANP release with reciprocal intracellular ANP reduction. When muscarinic receptors were stimulated by acetylcholine, ANP release was accelerated and intracellular ANP reduced. The activation of the phosphatidylinositol system, which is a common pathway for muscarinic and alpha-1 adrenergic receptor stimulation, was thus considered to regulate ANP release, but not ANP production.

Acetylcholine↗
PubMed1988

Prevalence of fatty liver in a general population of Okinawa, Japan.

A total of 2,574 residents in Yaeyama District of Okinawa, Japan, were investigated using real time ultrasonography to determine the real prevalence of fatty liver in the general population and to define its associated factors. Overall prevalence of fatty liver was 14.0%. Prevalence of fatty liver in persons under 19 years old was only 1.2%, and increased with age to a maximum in persons 40-49 years of age and then decreased. For persons over 20 years old, obesity index and serum levels of triglyceride and total cholesterol were measured, and alcohol consumption was asked. Prevalence of fatty liver was significantly higher in drinkers than non-drinkers (p less than 0.01), and increased with alcohol consumption. Furthermore, in persons not suffering from obesity prevalence of fatty liver was significantly higher in drinkers than in non-drinkers (p less than 0.001). The results of logistic regression analysis indicated that obesity and elevated serum triglyceride level in both sexes, and alcohol in males were significant predictors of fatty liver. In conclusion, prevalence of fatty liver increased with age to a maximum in persons 40-49 years of age and overall was 14.0%. Obesity was the strongest associated factor in both sexes and in males alcohol was also a strong factor.

Age Factors↗
PubMed1988

An outbreak of influenza A (H3N2) in a hospital for the elderly with emphasis on pulmonary complications.

From Dec 1, 1985 to Jan 18, 1986, 133 of 379 (35.1%) mainly elderly in-patients at a hospital in Fukuoka City were infected with influenza virus A (H3N2). In 32 of the 133 (24.1%) infected with the virus, pneumonia occurred. The occurrence was significantly higher in man (33.1%) than in women (17.1%) (p less than 0.05), and the same occurrence was found to be higher in bed-ridden patients (32.7%) than in ambulatory patients (17.3%) (p less than 0.05). It was also higher in those age 70 or older (25.4%) than in those 69 years or younger (17.4%), but with no statistical difference. Seven men and one woman, all 70 years old or older, infected with the virus died of pneumonia. The overall case-fatality ratio was 6.0%. Thus, male bed-ridden patients aged 70 years or older are highly vulnerable to pneumonia in case of infection with influenza virus A.

Aged↗
PubMed1988

Electrocardiographic changes related to hypersecretion of catecholamine in a patient with fulminant hepatitis.

A 48 year-old-man, with fulminant hepatitis complicated with myocarditis was treated. Despite intensive care, he died of fulminant hepatitis associated with hepatitis B virus infection. Electrocardiography (ECG) showed myocardial infarction-like changes when he went into a deep coma. Microscopically, scattered foci of myocardial cell damage and cell death associated with clusters of inflammatory cells were present in the heart at autopsy. However, there were no findings related to myocardial infarction and staining for hepatitis B surface antigen and core antigen were nil. The concentration of plasma catecholamine was elevated concomitantly with high level of ECG changes. We consider that abnormal ECGs may reflect a hypersecretion of catecholamine and suggest that our patient had a catecholamine cardiopathy.

Catecholamines↗
PubMed1988

Effects of salt and DOCA on hypothalamic and baroreflex control of blood pressure.

Cardiovascular and sympathetic nerve responses to electrical stimulation of either the aortic depressor nerve (ADN) or the posterior hypothalamus were recorded from rats treated with salt, DOCA, or DOCA/salt and compared with those from untreated controls. By the 7th day, tail-cuff systolic pressures were significantly elevated in rats treated with salt or DOCA/salt. And by the 21st day, all treated rats (i.e. with salt, DOCA, or DOCA/salt) had elevated pressures together with attenuated ADN responses and augmented hypothalamic responses. After 5 days, DOCA/salt treated rats already had attenuated responses to ADN stimulation and augmented responses to hypothalamic stimulation even though their systolic pressures were still unaltered. These findings suggest that combined treatment with salt and DOCA altered central blood pressure regulation even before hypertension developed.

Animals↗
PubMed1988

[Morphological characteristics of the left ventricle with volume-and pressure-overload in valvular heart diseases].

There are some cases in which pump function of the left ventricle (LV) is not sufficiently improved despite of successful operation, especially in advanced hypertrophy. The impaired pump function is believed to result from irreversible myocardial damage. Thus, the present study is designed to make clear the histopathological changes of the LV muscle in hypertrophied hearts. Fifty-six patients with volume-overloaded hearts (27 with AR, 24 with MR, and 4 with AR and MR) and 10 patients with AS were examined. Cardiac muscle specimens for histological examination were obtained from the LV anterior wall. In volume-overloaded hearts, the muscle cell diameters were correlated with both LV dimension (LVDd and LVDs) and LV volume index (LVEDVI and LVESVI). The progress of interstitial fibrosis was correlated with LV volume index. Five of the 9 patients with massive myocardial hypertrophy (in all cases, muscle cell diameter was greater than 30 microns) did not show any improvement in histological figure after operation and displayed persistent postoperative LV dilatation. Patients with either LVDd greater than 75mm and LVDs greater than 55mm or LVEDVI greater than 200ml/m2 and LVESVI greater than 100ml/m2, whose hearts showed massive myocardial hypertrophy and severe fibrosis, tended to have postoperative cardiac dysfunction. In pressure-overloaded hearts, the muscle cell diameters were correlated with LVPWTh and LVESVI. Noteworthily, fibrosis and degeneration of muscle fibers were slight as compared with advanced myocardial hypertrophy.

Cardiomyopathy, Hypertrophic↗