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Y Nara

Publications and source records attributed to Y Nara.

At least 109 records · Page 6Linked to original sources
PubMed1992

Potassium accelerates urinary sodium excretion during salt loading without stimulating atrial natriuretic polypeptide secretion.

1. Effects of potassium (K) supplementation (100 mEq/day) on urinary sodium (Na) excretion and on the secretion of atrial natriuretic polypeptide (ANP) during salt loading (350 mEq/day) were studied in 12 healthy salt-resistant normotensives under strictly controlled metabolic ward conditions. 2. Urinary volume and Na excretion on the first day of the high salt period (HSP) were significantly greater in the K-supplemented group (KG) than in the control group (CG). 3. There was a significant gain in bodyweight after salt loading in both groups, with a significantly greater gain in CG on the second day of HSP. Haematocrit decreased significantly during salt loading in both groups, the degree of which was significantly greater in CG. 4. Plasma norepinephrine decreased significantly during salt loading in both groups, the degree of which was significantly less in KG than in CG. A significant increase in plasma ANP was observed in CG on and after the second day of HSP, while a significant increase in plasma ANP was observed on the fifth day of HSP in KG. 5. These findings indicate that K supplementation accelerates diuresis and natriuresis, resulting in moderate suppression of volume expansion induced by salt loading and that this accelerated diuresis and natriuresis is not a result of the action of ANP.

Adult↗
PubMed1992

International cooperative study on the relationship between dietary factors and blood pressure: a preliminary report from the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. The CARDIAC Cooperative Study Research Group.

1. To investigate the epidemiological relationship of dietary factors to blood pressure (BP) and major cardiovascular diseases, we carried out the international cooperative Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study, which so far involves 48 centers in 20 countries as of August 1991. From each population, 100 men and 100 women aged 50-54 years were randomly selected for BP measurement, 24-h urine collection, blood tests, and medical interview. Various biological markers of diets from urine and blood were analyzed centrally in the Izumo CARDIAC center. 2. Cross center analysis using simple linear regression revealed strong significant correlations of body mass index (BMI) to systolic BP (SBP; p < 0.01) and diastolic BP (DBP; p < 0.001) in men. 24-h urinary sodium (Na) excretion in men also showed significant correlations with SBP (p < 0.05) and DBP p < 0.05) even after controlling for the effect of BMI (SBP; p < 0.05, DBP; p < 0.05). 3. Within center analysis using multiple linear regression implied that BMI and Na strongly adversely affect BP, whereas magnesium may have beneficial influence on BP. 4. Multicolinearities among 24h urinary sodium, calcium, and urea nitrogen were noted in men.

Body Mass Index↗
PubMed1992

Granulomatous angiitis of the central nervous system--a case with recurrent intracerebral hemorrhage.

Granulomatous angiitis of the central nervous system occurred in a 43-year-old male presenting with recurrent intracerebral hemorrhage confirmed by computed tomography. A surgical specimen obtained at hematoma removal revealed granulomatous angiitis. Systemic investigation found no underlying cause for the hemorrhage. Although the incidence is very low, this condition should be considered in cases of recurrent intracerebral hemorrhage with unknown cause. When surgery is indicated, biopsy of the brain and leptomeninges should be obtained, because involvement of the leptomeninges has occurred in virtually all autopsy cases.

Adult↗
PubMed1992

Preventive effect of manidipine on severe hypertension and proteinuria induced by the inhibition of endothelial-derived relaxation factor formation in stroke-prone spontaneously hypertensive rats.

The effect of a calcium antagonist, manidipine, on blood pressure and proteinuria induced by the inhibition of endothelial-derived relaxation factor (EDRF) formation was examined. Manidipine attenuated the increase in blood pressure and prevented proteinuria caused by renal damage associated with the inhibition of EDRF formation in stroke-prone spontaneously hypertensive rat (SHRSP) and Wistar Kyoto (WKY) rats.

Animals↗
PubMed1992

Gene-environment interaction in hypertension, stroke and atherosclerosis in experimental models and supportive findings from a world-wide cross-sectional epidemiological survey: a WHO-cardiac study.

1. Genetic rat models of hypertension, such as spontaneously hypertensive rats (SHR) and in particular, stroke-prone SHR (SHRSP) are useful models for research on the genetic pathogenesis, gene-environment interaction and control of environmental factors for the prevention of hypertension and related cardiovascular diseases (CVD). 2. Since recent genetic analysis of hypertension in SHRSP indicated that one of the hypertensive genes related to salt-induced blood pressure (BP) rise was linked with the gene of the angiotensin-converting enzyme, gene-environment interaction is important in the humoral, neural, vascular and nutritional mechanisms of hypertension and CVD. 3. Extensive experimental studies in SHRSP by the authors have demonstrated nutritional factors counteracting directly or indirectly against the adverse effect of excess salt intake, such as K, Mg, Ca, dietary fibres, protein, some amino acids and fatty acids, etc.; they are therefore effective in preventing stroke, the typical complication of hypertension. 4. Experimental atherosclerotic models were established in SHRSP, which indicated also a gene-environment interaction in the pathogenesis of atherosclerosis at the cellular level of vascular smooth muscle cells. Excess salt intake accelerated cholesterol absorption from the intestine to induce arterial fat deposition as well as to active platelet aggregation by the mechanism of increased intracellular Ca2+ mobilization. 5. Based on such experimental findings on the hypertension and related CVD prevention, a cross-sectional multicentre epidemiological 'CVD and Alimentary Comparison' Study (WHO-CARDIAC Study) was designed to assess the relationship of biological markers of dietary factors with BP ('core' study) and major CVD mortalities ('complete' study) and has been successfully undertaken for the past 8 years in co-operation with 54 centres in 23 countries. 6. The results of 'core' study so far obtained by cross-centre simple linear regression analysis demonstrated adverse effects of body mass index and salt intake on BP in men and possible beneficial effects of Mg by within-centre multiple linear regression analysis. 7. Preliminary cross-centre simple linear regression analysis of the 'complete' study indicated a positive correlation of serum cholesterol levels and negative correlation of serum phospholipid poly-unsaturated to unsaturated fatty acid ratios and 24 h urinary taurine excretion with coronary heart diseases mortality; a positive correlation of 24 h urinary Na and Na/K ratios and a negative correlation of serum cholesterol levels with stroke mortalities was indicated. 8. These epidemiological data confirmed mostly the applicability of experimental findings to the nutritional prevention of hypertension and CVD prevention.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Ethnic differences in salt sensitivity: genetic or environmental factors?

1. The CARDIAC study, a world-wide cross-sectional epidemiological study on the relationship between alimentary factors and cardiovascular diseases, provided the initial evidence of ethnic differences in salt sensitivity; this was because despite much less urinary sodium excretion in Tanzania than in Brazil and the Japanese, the prevalence of hypertension was relatively higher in Tanzania than in the latter two populations. 2. To investigate this difference in salt sensitivity, a standardized clinical experiment was carried out: six to 13 male volunteers were placed on 2500 kcal basal diets containing 3 g salt/day. Eighteen grams of salt were added daily from the sixth to the 11th day in Tanzania and Brazil, while 22 g of salt were added in Japan. 3. Salt loading induced a significant rise in systolic blood pressure (SBP) on the second day of the high salt period (HSP) in Japan, the second and third day of HSP in Brazil, and all days of HSP in Tanzania. 4. Salt sensitivity was seen in 16.7% of the participants in Japan, 36.4% in Brazil and 46.2% in Tanzania. Further analysis of the effect of salt on blood pressure (BP) was carried out using the data from the CARDIAC study by multiple regression analysis. A within-centre comparison of fatty acid was also made. 5. The regression analysis revealed that the relationship of salt and blood pressure is more positively tight in Tanzania than Brazil and Japan after controlling for other confounding variables. Fatty acids in serum phospholipids contain significantly more palmitic acid and showed lower P/S ratios than those from Brazil and Japan.

Adult↗
PubMed1992

Family history study on hypertension in Japan.

1. Familial aggregation of hypertension was determined in 187 Japanese nuclear families. The necessary data on family and case history particularly concerning the hypertensive status were obtained by personal interviews of outpatients at six local hospitals, using a specifically designed questionnaire. 2. From the family history of the 187 living index children (single ascertainment), 134 pairs of parents were informative. Of 819 children, excluding index cases, the number of hypertensives, normotensives and status unknown were 224, 274 and 187, respectively. Individuals under 30 were classified as unknown. 3. For a child given the birth order, empirical risk to be hypertensive was calculated from the proportion of hypertensives to normotensives plus hypertensives. 4. Irrespective of parental mating types, among a simplex family of hypertension the index cases of the first-born child were more than the others. 5. There was no birth order effect in risk among multiplex families of hypertension. 6. There was no increase of hypertensive offsprings observed when the mother was hypertensive.

Family↗
PubMed1991

Blood pressure cosegregates with a microsatellite of angiotensin I converting enzyme (ACE) in F2 generation from a cross between original normotensive Wistar-Kyoto rat (WKY) and stroke-prone spontaneously hypertensive rat (SHRSP).

We investigated the linkage between high blood pressure and the ACE gene in the F2 generation between SHRSP/Izm and WKY/Izm. The male F2 rats were categorized into 3 genotypes according to a microsatellite polymorphism in the ACE gene. Significantly high blood pressure was observed in the SHRSP homozygotes when it was compared to the blood pressure of the heterozygotes. Further, after 2 or 3 months salt-loading, the blood pressure was significantly higher in the SHRSP homozygotes than in the heterozygotes and the WKY homozygotes. The heterozygotes had a blood pressure similar to that in the WKY homozygotes, indicating that the effect of the ACE gene genotype was recessive. Salt appetite was neither correlated with the salt-sensitivity nor cosegregated with the ACE genotype. The results indicate that the locus of ACE gene associates with the development of hypertension, especially salt-sensitive hypertension.

Animals↗
PubMed1991

Immunohistochemical characterisation of extracellular matrix components of salivary gland tumours.

Proteoglycans (PGs) were localised immunohistochemically in 52 salivary gland tumours including pleomorphic adenoma, adenoid cystic carcinoma, acinic cell carcinoma, oncocytoma, mucoepidermoid carcinoma, clear cell tumour and Warthin tumour, using antibodies raised against large PG, small PG, chondroitin 4-sulphate PG, chondroitin 6-sulphate PG, heparan sulphate PG and keratan sulphate PG. Large PGs were mainly observed in mucinous materials of extracellular matrix (ECM) and interstitial fibrous element of tumour tissues, while small PGs were located only in hyaline matrix and surrounding fibrous (capsular) connective tissues. Chondroitin 6-sulphate PG was detected in the ECM of pleomorphic adenomas and clear cell carcinomas and in pseudocystic spaces of adenoid cystic carcinomas, but only in vessel walls in non-neoplastic tissues. Keratan sulphate PG was observed to locate in mucinous material of pleomorphic adenomas, acinic cell carcinomas and clear cell carcinomas, but not in the adenoid cystic carcinomas examined, and it was also unobservable in non-neoplastic salivary gland tissues. Heparan sulphate PG was observed on the inner surfaces of true ductal spaces of adenoid cystic carcinomas and on cell surfaces of oncocytoma cells. By HPLC analysis, individual glycosaminoglycans contained in tumour tissues were compared. Chondroitin 6-sulphate PG was very rich in ECM of pleomorphic adenomas and adenoid cystic carcinomas. Pleomorphic adenomas contained relatively more low-sulphated chondroitin sulphate than adenoid cystic carcinomas and other tumours.

Chondroitin Sulfates↗
PubMed1991

Chloride ion ingested with sodium affects the development of cerebral lesions in stroke-prone spontaneously hypertensive rats.

1. To determine the effect of chloride ion on the development of hypertension and the incidence of cerebral lesions in stroke-prone spontaneously hypertensive rats (SHRSP), groups of 10 rats were administered chronically with either 171 mmol/L sodium chloride or equimolar sodium provided as sodium citrate in the drinking water from the age of 12 weeks. 2. The life span was significantly extended in SHRSP given sodium citrate (336 +/- 28 vs 246 +/- 26 days, mean +/- s.e.m., P less than 0.05) but their development of hypertension was not different from SHRSP given sodium chloride. 3. In order to determine the role of calcium homeostasis, calcium in urine was collected. Urinary calcium in SHRSP given sodium citrate was significantly decreased (1.0 +/- 0.12 vs 1.8 +/- 0.18 mg/24 h urine, P less than 0.05). 4. If the normal life span is 320 +/- 35 days, this suggests that chloride ion ingested with sodium accelerates the development of cerebrovascular diseases, and that increased urinary calcium excretion may be related to this adverse chloride effect on the development of hypertension in SHRSP.

Animals↗
PubMed1991

L-nitroarginine increases blood pressure in the rat.

1. Effects of administration of NG-nitro-L-arginine (NO2Arg), a guanidino nitroarginine derivative, for 1 week on blood pressure and some vascular responses of rats were studied. 2. A significant rise of the systolic blood pressure was observed after the administration of NO2Arg with food (0.023% in weight, about 2.8 mg of NO2Arg per rat per day). Relaxation by acetylcholine decreased markedly in ring preparations of the thoracic aorta of NO2Arg-treated rats. However, glyceryltrinitrate-induced relaxation was not reduced after NO2Arg administration, suggesting that NO2Arg administration specifically inhibited endothelium-dependent relaxation. 3. An increase of blood pressure may be because oral administration of NO2Arg inhibited endothelium-dependent relaxation in vivo suggesting that the release of EDRF is important in physiological control of blood pressure.

Animals↗
PubMed1991

Activation of Na+/H+ exchange is unnecessary in the induction of c-fos mRNA in serum-stimulated vascular smooth muscle cells.

1. The effects of extracellular Na+ concentration ([Na+]o) on serum-stimulated c-fos mRNA induction in vascular smooth muscle cells (VSMC) were studied to examine whether the activation of Na+/H+ exchange and the following intracellular alkalinization are necessary in the induction of c-fos in VSMC. 2. When monitored with 2', 7'-bis (carboxylethyl)-5(6)-carboxyfluorescein, the reduction in [Na+]o in HCO(3-)-free buffer caused a dose-dependent inhibition of Na(+)-dependent intracellular pH recovery in acid-loaded VSMC. In addition, serum-stimulated intracellular alkalinization in VSMC was completely blocked by the removal of extracellular Na+. 3. By contrast, c-fos induction, quantified by slit blot hybridization of c-fos mRNA, was not fully inhibited by the reduction of [Na+]o. Furthermore, amiloride and ethylisopropyl-amiloride, inhibitors of Na+/H+ exchange, only partially blocked c-fos induction by serum. 4. We concluded from the observation above, that the intracellular alkalinization caused by the activation of Na+/H+ exchange was unnecessary in serum-stimulated induction of c-fos mRNA in VSMC.

Animals↗
PubMed1991

Intracellular pH and sodium-proton exchange activity of lymphocytes in stroke-prone spontaneously hypertensive rats.

1. At the age of 20 weeks, intracellular pH (pHi) of circulating lymphocytes suspended in HCO(3-)-free NaCl media was not significantly different between stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY). 2. The initial recovery rate of pHi in lymphocytes tended to be greater in SHRSP than in WKY after the addition of 60 mmol/L or 120 mmol/L of NaCl, but there was no statistically significant difference. 3. The H+ equivalent efflux rate, which was a true reflection of Na(+)-H(+) activity, was significantly greater in SHRSP than in WKY (P less than 0.05). The difference in H+ equivalent efflux rate was not due to the difference in cellular buffering power between the two groups (P greater than 0.05). An increased Na(+)-H(+) exchange activity may play a partial role in the pathogenesis of hypertension.

Animals↗
PubMed1991

Genetic factors regulate the rise in blood pressure in F2 generation crossed between stroke-prone spontaneously hypertensive rats and Wistar-Kyoto rats.

1. There was no significant difference between the systolic blood pressure (SBP) of offspring derived from SHRSP mother and WKY father and the SBP of offspring derived from WKY mother and SHRSP father at the developing stage (5-13 weeks of age). 2. The degree of genetic determinations of SBP in stroke-prone spontaneously hypertensive rat (SHRSP) at 5, 7, 10 and 13 weeks of age, determined by genetic crosses between SHRSP and WKY, was 73.9, 70.8, 50.2 and 55.3% respectively. 3. Significant correlations between SBP at 5 and 7 weeks, 7 and 10 weeks, 10 and 13 weeks, also at 5 and 13 weeks of age in F2 generation crossed between SHRSP and WKY were observed. SBP falling at or above the 80th percentile group in F2 generation at 5 weeks of age were constantly higher than SBP falling at or below the 20th percentile group from 7 weeks of age onwards. 4. These results indicate that there exists 'tracking phenomenon of SBP in SHRSP' and that genetic factors regulate the rise in SBP. Tracking of SBP in F2 generation gives us new methodological insight into hypertensive mechanism in SHR.

Animals↗
PubMed1991

Comparison of vasopressor effects of nitro arginine in stroke-prone spontaneously hypertensive rats and Wistar-Kyoto rats.

1. NG-nitro-L-arginine (NO2Arg) is a guanidine nitro arginine derivative and an inhibitor of endothelium-dependent vascular relaxation. Significant rise of the systolic blood pressure was observed after 1 week administration of NO2Arg in food (0.023% in weight, about 2.8 mg of NO2Arg/rat per day) in female rats of stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY). The rises were not different between SHRSP (21 mmHg) and WKY (23 mmHg). 2. In ring preparations of the thoracic aorta of NO2Arg-administered rats of both strains, relaxation by acetylcholine decreased markedly compared with those of the control rats (to 43-44%). On the contrary, glyceryltrinitrate-induced relaxation was slightly but significantly increased in the aorta of WKY after NO2Arg administration and the same tendency was observed in SHRSP. 3. The rise of blood pressure and the decrease of acetylcholine-induced relaxation suggested that NO2Arg inhibited the endothelium-dependent relaxation not only in WKY but also in SHRSP. The relaxation of the thoracic aorta preparation of SHRSP by acetylcholine was much less (ca 38%) than that of WKY; however, that of SHRSP by glyceryltrinitrate was slightly less (ca 74%), indicating that endothelium-dependent relaxation declined in vascular preparation of SHRSP. 4. The present results suggest that endothelium-dependent relaxation has some contribution on blood pressure regulation in the hypertensive state, although a decline of endothelium-dependent relaxation is evident in vascular preparation of SHRSP compared with WKY.

Acetylcholine↗
PubMed1991

Genetic heterogeneity of the spontaneously hypertensive rat.

We examined DNA fingerprints of the spontaneously hypertensive rat from Shimane Institute of Health Science, Izumo, Japan, including seven substrains that were separated in the early stages of the establishment of the stroke-prone spontaneously hypertensive rat, and compared their fingerprints with those of rats from other sources. Obtained DNA fingerprints revealed that, in both the stroke-resistant spontaneously hypertensive rat and the Wistar-Kyoto rat, there is a substantial genetic difference between the rats from the National Institutes of health and from Shimane Institute of Health Science. By contrast, only a small genetic difference was observed either between the rats from the National Institutes of Health and Charles River Laboratories or among the substrains of the spontaneously hypertensive rat in the Shimane Institute of Health Science. Further, in the strains from the Shimane Institute of Health Science, there were fingerprinting bands that could distinguish either the Wistar-Kyoto rat from all the substrains of the spontaneously hypertensive rat or the stroke-prone from the stroke-resistant spontaneously hypertensive rat in spite of their close genetic backgrounds. From the observations above, we concluded 1) that there is substantial genetic variance of the spontaneously hypertensive rat between the two major sources in the world, the National Institutes of Health and the Shimane Institute of Health Science and 2) that by DNA fingerprinting analysis, it is possible to identify the restriction fragment length polymorphisms that are specific for the spontaneously hypertensive rat or the stroke-prone spontaneously hypertensive rat. These polymorphisms can be applied in the segregation study of the F2 generation.

Animals↗