Biomedical subjects

Y Nara

Publications and source records attributed to Y Nara.

At least 127 records · Page 7Linked to original sources

PubMed1991

Indirect systolic and mean blood pressure determination by a new tail cuff method in spontaneously hypertensive rats.

A new tail cuff method for determining systolic and mean blood pressure in rats was developed based on photoelectric detection of tail arterial blood flow and pulsatile volume oscillation. Indirect systolic and mean blood pressure measured by this method correlated well with direct systolic and mean blood pressures recorded by a transducer and polygraph after carotid artery cannulation in stroke-resistant spontaneously hypertensive rats (SHR), stroke-prone SHR and normotensive Wistar Kyoto rats. Blood pressures were sharply, and transiently raised for about 1 min when rats were picked up by an investigator to be placed in a hot box or immobilized in a restrainer for measuring blood pressure. Therefore, blood pressures should be measured at least 1 min after the rats are put in a restrainer. This new tail cuff method for measuring blood pressure provides reliable mean blood pressure readings in conscious rats.

Animals↗

PubMed1991

Stroke-prone SHR (SHRSP) as a model for osteoporosis.

Since previous studies on SHRSP showed various abnormalities in Ca metabolism, aged SHRSP together with age-matched Wistar-Kyoto (WKY) were examined for bone mineral density and contents as well as bone histomorphometry and mechanical properties. SHRSP and WKY, 10 rats of each group at the age of 7 to 8 months were sacrificed with or without tetracycline and calcein labellings for the estimation of mineral appositional rate. Both femurs, tibia and the 1st lumbar vertebra were extirpated from each rat; one femur was used for mineral density and content analyses and the other was used for analyzing mechanical properties by three point-bending and torque methods (Maruto, MZ500D). Mineral density and cortical thickness index were decreased significantly in SHRSP compared with WKY, and Ca contents were decreased as well. Correspondingly femurs from SHRSP were proven to be fragile in the maximum bending stress. Undecalcified histological sections of tibial proximal epiphysis histomorphometrically indicated bone volume and trabecular thickness were significantly decreased in SHRSP. These findings together with others indicate SHRSP can be a good model for spontaneous osteoporosis in man.

Animals↗

PubMed1991

Differences in response between SHRSP and WKY vascular smooth muscle cells to inhibition of cell proliferation by sodium nitroprusside.

The effects of sodium nitroprusside on the proliferation of cultured vascular smooth muscle cells (SMC) from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY) were examined. Sodium-nitroprusside (SNP, 1mM) inhibited DNA synthesis by SMC from SHRSP and WKY by 90% and 95%, respectively. SNP also decreased cell proliferation. However, SNP was inactive when SMC were pretreated 6 and 12 hrs before growth stimulation by FCS. On the other hand, the inhibitory action of SNP decreased with time (posttreatment) in SHRSP SMC (42% inhibition at 12 hr post addition). However, in WKY SMC, the decrease of inhibitory action was very slight and SNP still inhibited 73% of DNA synthesis at 12 hr post treatment. SNP inhibited RNA synthesis for 3-6 hr and 6-9 hr after FCS stimulation, however no difference was noted between SHRSP and WKY. Protein synthesis was inhibited more strongly by SNP (9-12 hr after FCS stimulation) in WKY SMC than SHRSP SMC. It is probable that the specific protein(S) whose synthesis is inhibited by SNP is/are responsible for the differences in cell proliferation rate between SHRSP and WKY SMC.

Animals↗

PubMed1991

Aggravating effects of isolated caging on the development of hypertension and its complications in stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY).

Stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY) were maintained in isolation or in group to analyze the effect of isolation, one type of emotional stress, on the development of hypertension and its complications. SHRSP kept isolated during the whole or a half of the experimental period developed severer hypertension within a shorter period than those kept together with other animals throughout the experiment, and showed significantly higher incidences of cerebral stroke (40 or 33%) than the latter (8.3%). Histological and pathophysiological studies revealed pituitary-adrenal and cardiac hypertrophy accompanying more accelerated urinary epinephrine (E) excretion which indicated emotional stress caused by isolation might aggravate pathological lesions in hypertension. Neither WKY in isolation nor in groups developed hypertension, although isolated WKY had significantly heavier pituitary and adrenal glands accompanied with more accelerated urinary E and calcium excretions than WKY kept in groups.

Animals↗

PubMed1991

Hypertensive diabetic rats: different effects of streptozotocin treatment on blood pressure in adult SHR and in neonatal SHR.

The effect of streptozotocin (STZ) treatment on blood pressure in adult spontaneously hypertensive rats (SHR) was compared with that in neonatal SHR. Three-month-old SHR were intravenously given 10, 30 or 50 mg/kg of STZ. When STZ was given in adult SHR, weight loss, overt hyperglycemia and the reduction of blood pressure occurred dose dependently. Two-day-old pups from SHR were subcutaneously injected with 100 mg/kg of STZ. Neonatal STZ treatment did not attenuate the development of hypertension in SHR. Since neonatally STZ-treated SHR develop mild diabetic symptom with hypertension and develop mild diabetic glomerulosclerosis, they are a good model for studying vascular complications or other disorder relating to the synergism between hypertension and diabetes mellitus.

Animals↗

PubMed1991

Detailed disease processes of cerebral pericytes and astrocytes in stroke-prone SHR.

We examined ultrastructurally cerebral pericytes and astrocytes in 20 normotensive Wistar Kyoto rats and 60 asymptomatic stroke-prone spontaneously hypertensive rats, which were sequentially killed at 4-52 weeks of age. Another 30 SHRSP were killed soon after they showed symptoms of stroke. We found two kinds of pericytes around the capillaries; granular pericytes and filamentous pericytes. Granular pericytes possibly serve as scavenger cells in the central nervous system and became active and grew in size with time. In contrast, filamentous pericytes degenerated during the development of hypertension. Degeneration of the filamentous pericytes was involved in an increase of endothelial permeability. Increased permeability caused focal and then circumferential swelling of the astrocytes around the capillaries. Swelling of the astrocytes seemed to accelerate the production of attachment plaques. Following this increase in the number of attachment plaques, numerous astrocytic filaments were produced within the cytoplasm. As a result, fibrous astrocytes were fully developed. Adjacent to the fibrous astrocytes we detected opening of the interendothelial junctions as well as dead neurons. From these observations we propose that astrocytes perform the main function in trophic interactions among cerebral endothelial cells, astrocytes, and neurons and that dysfunction of astrocytes disturbs the neural environment, resulting in neuronal death.

Animals↗

PubMed1991

Initial renal growth in diabetic and sodium-loaded spontaneously hypertensive rats (SHR).

An increase in kidney size in experimental diabetic rats is ascribed to local somatomedin C (SM-C) formation. In the present study, we compared the nature of the initial kidney growth following sodium-load in spontaneously hypertensive rats (SHR) with that in streptozotocin-induced diabetic SHR. After 6 d of each treatment, the kidney weight increased in both groups. SM-C levels in the kidney increased in diabetic SHR on day 2, unaccompanied by any considerable change in plasma SM-C. In sodium-loaded SHR, kidney SM-C content was not changed and plasma SM-C rather declined on day 6. Protein content including both non-collagen protein and collagen protein increased in both diabetic and sodium-loaded groups, whereas DNA content increased only in the latter group. Protein/DNA ratio increased in diabetic rats but not in sodium-loaded animals. It may be estimated, therefore, that diabetic kidney growth in SHR is mainly due to cellular hypertrophy which is related to SM-C formation, while kidney growth following sodium-load is due to hyperplasia which may be independent of local SM-C formation.

Animals↗

PubMed1990

Immunohistochemical characterization of extracellular matrix components of yolk sac tumors.

Proteoglycans (PGs) were isolated from yolk sac tumor and chondroitin sulfate large PG (core molecule with a molecular weight congruent to 200,000) and small PG (core molecule with a molecular weight congruent to 50,000) were detected. Immunohistochemical localization of PGs in three yolk sac tumors was investigated using monoclonal antibodies raised against both small and large PGs, which were purified from human ovarian fibroma capsule and a yolk sac tumor, respectively. The localization of large PG was observed to be distinct from that of small PG. A markedly positive reaction for antibody against large PG was observed in myxomatous areas, perivascular and perivesicular portions; hyaline globules were the most intensely reactive. In the areas showing a polyvesicular vitelline tumor pattern, the compact connective tissue stroma consisted of small PGs. It is conceivable that large PGs are synthesized by immature mesenchymal cells and also by epithelial-like cells as a basement membrane component, whereas small PGs are synthesized by mature fibroblastic cells synthesizing collagen. Immunohistochemical localization of other extracellular matrix components (laminin, fibronectin, type I-IV collagen) was also studied in relation to PG localization.

Adult↗

PubMed1990

Ovarian epithelial tumors of borderline malignancy in Japan.

Seventy-one cases of ovarian epithelial tumor of borderline malignancy have been surveyed from a clinicopathologic viewpoint. The majority of the borderline tumors (73.2%) were of the mucinous type, versus only 16.9% of the serous type. The other types--endometrioid (2.8%), Brenner (1.4%), and mixed type (5.6%)--were much rarer. Patients with mucinous tumors were significantly younger (mean age 42.6) than those with serous tumors (mean age 57.5) (P less than 0.01). Of patients with mucinous tumors, 64.2% were of reproductive age (15-45 years), compared with 17% of patients with serous tumors. Some 78.8% of mucinous and 83.3% of serous borderline tumors were FIGO stage I. Serous tumors were more frequently bilateral (66.7%) than mucinous tumors (9.8%). In mucinous borderline tumors, the extent of tumor spread at the first laparotomy had an intimate relationship to the prognosis, but in serous borderline tumors, it was insignificant. The survival rate of patients with mucinous borderline tumors was 69.3% at 5 years and 62.4% at 10 years (Kaplan-Meier method). Most patients with pseudomyxoma peritonei classified as borderline at the time of discovery died within 5 years of the operation. The prognosis of the serous type was extremely favorable. Criteria for borderline tumors of various cell types and differences in the clinicopathologic data of ovarian borderline tumors between Japan and other countries were discussed.

Adenocarcinoma↗

PubMed1990

Study of ovarian tumors treated at Nagoya University Hospital, 1965-1988.

The relative frequency and the age distribution of ovarian tumors (873 primary and 47 secondary tumors) encountered over 23 years at Nagoya University Hospital were examined with respect to histological type and grade of malignancy. Of the primary neoplasms, common epithelial tumors accounted for 56.6%, sex cord-stromal tumors for 7.3%, and germ cell tumors for 39.5%. Among 296 cases with primary malignant neoplasms, common epithelial type accounted for 75.6%, sex cord-stromal tumors for 4.7%, and germ cell tumors for 19.6%. A review of the literature from Western countries indicated that in Japan, the relative frequency of common epithelial tumors is lower but that of germ cell tumors, especially malignant germ cell tumors, is higher. The difference in the incidence of germ cell tumors between Japan and Western countries is not considered significant, and the incidence of common epithelial tumors is considered to be much lower in Japan.

Adolescent↗

PubMed1990

Increased Na(+)-H+ exchange activity in cultured vascular smooth muscle cells from stroke-prone spontaneously hypertensive rats.

Na(+)-H+ exchange activities were studied in vascular smooth muscle cells (VSMC) obtained from stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY). The cytoplasmic pH of VSMC was detected by 2',7'-bis(carboxyethyl)-carboxyfluorescein (BCECF), which was used as a fluorescent pH probe with a fluorescent microplate reader; this enabled us to measure the cytoplasmic pH of cells attached to multiwell culture plates. We measured cytoplasmic pH recovery in quiescent VSMC after acid loading with 20 mmol/l NH4Cl in HCO3(-)-free buffer. This recovery was inhibited either by removal of extracellular sodium or by addition of 5-N-ethyl-N-isopropyl amiloride (EIPA). The initial recovery rate was dependent on extracellular sodium concentration. Therefore, this change in cytoplasmic pH was presumed to be due to amiloride-sensitive Na(+)-H+ exchange. The Na(+)-H+ exchange activity represented by the cytoplasmic pH recovery rate was significantly higher in VSMC from SHRSP than in WKY cells at extracellular sodium concentrations greater than or equal to 20 mmol/l. In contrast, the steady-state cytoplasmic pH of quiescent VSMC from SHRSP was lower than that of WKY cells in HCO3(-)-free buffer. These findings seemed to contradict each other, and suggested that cytoplasmic pH was regulated not only by Na(+)-H+ exchange but also by other complicated mechanisms.

Animals↗

PubMed1990

Ultrastructural changes in cerebral pericytes and astrocytes of stroke-prone spontaneously hypertensive rats.

We examined the ultrastructure of cerebral pericytes and astrocytes in 20 normotensive Wistar-Kyoto rats and 60 asymptomatic stroke-prone spontaneously hypertensive rats killed at 4-52 weeks of age. Another 30 stroke-prone spontaneously hypertensive rats were killed soon after they showed symptoms of stroke. We found two kinds of pericytes around the capillaries: granular pericytes and filamentous pericytes. Granular pericytes possibly serve as scavenger cells in the central nervous system and became active and grew in size with time. In contrast, filamentous pericytes degenerated during the development of hypertension. Degeneration of the filamentous pericytes was involved in an increase of endothelial permeability. Increased permeability caused focal and then circumferential swelling of the astrocytes around the capillaries. Swelling of the astrocytes seemed to accelerate the production of attachment plaques. Following this increase in the number of attachment plaques, numerous astrocytic filaments were produced within the cytoplasm. As a result, fibrous astrocytes were fully developed. Adjacent to the fibrous astrocytes we detected opening of the interendothelial junctions as well as dead neurons. From these observations we propose that astrocytes perform the main function in trophic interactions among cerebral endothelial cells, astrocytes, and neurons and that dysfunction of astrocytes disturbs the neural environment, resulting in neuronal death.

Animals↗

PubMed1990

Estimation of protein intake: comparison of dietary assessment and urinary excretion.

Estimates of dietary intake of nutrients have many problems, and confirmation of these estimates by chemical measurements of excretory products helps to establish their validity. The correlation between urinary amino acid excretion and dietary history of protein intake are reported herein. Diet diaries were kept by and 24-h urine collected from participants in the Trial of Antihypertensive Therapy and Management, a multicenter cooperative trial comparing the effects of drugs and diet on blood pressure control, side effects, and quality of life. The nutritional information was coded and the data stored by the nutritional analyses facility at Albert Einstein College of Medicine. The chemical determinations were done in the laboratories of the Department of Pathology, Izumo, Japan. The correlation between total protein and 3-methylhistidine was r = 0.42 (n = 96). The correlation was similar for animal protein (r = 0.4). These correlations are of the same order of magnitude as those between dietary sodium and urine sodium, and dietary potassium and urine potassium. We conclude that measurement of urinary protein excretion products may be a useful way to estimate dietary protein intake.

Adult↗

PubMed1990

Diet and hypertension in Tanzania.

A survey was conducted on an urban population in the city of Dar es Salaam and on a rural community in both Handeni and the pastoral Masai in Monduli to investigate the relationship between diet and hypertension in Tanzania. Blood pressure (BP) was measured using an automatic BP-measuring machine. Biological markers of dietary intake were measured in 24-h urine and in blood. Hypertension was noted to be a bigger problem in the capital city, where the rate of obesity and salt intake were higher whereas potassium, protein, and polyunsaturated fatty acid intake were lower. Therefore, attention to dietary habits may reduce the growing problem of hypertension in Tanzania.

Adult↗

PubMed1990

Relationship between urinary amino acids and diets in Spanish Cardiovascular Diseases and Alimentary Comparison Study.

A randomized, cross-sectional study was carried out to examine dietary pattern and urinary amino acids excretion in two Spanish free-living populations. A total of 288 adults (50-54 years old; 50% men and 50% women), randomly selected from the census, took part in the study; of these, 146 were living in an urban district of Madrid and 142 in a rural area. Dietary intakes by 7-day recall questionnaires, smoking habits, and alcohol intake were examined in each participant, and 24-h urine was collected in aliquot cups designed for the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. All amino acid excretions averaged higher in men than in women in both areas, and higher in the urban than in the rural population. Main dietary differences between urban and rural populations were higher consumption of fish in urban than in rural populations and higher consumption of bread in rural than in urban populations. Urinary taurine excretion as well as 3-methylhistidine or histidine were significantly associated with fish and meat consumptions, respectively, estimated by 7-day dietary recall questionnaires.

Amino Acids↗

PubMed1990

Alcohol consumption as a risk factor for high blood pressure from the Cardiovascular Diseases and Alimentary Comparison Study. CARDIAC Cooperative Research Group).

The relationship between alcohol consumption and blood pressure (BP) was studied in 29 centers in 12 countries as part of the International Cooperative Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. From each population, 100 men and 100 women aged 50-54 were randomly selected for BP measurement by automated system and for a standardized interview to complete the questionnaire relating to alcohol consumption. In cross-center simple linear regression analysis, mean alcohol consumption calculated from a previous week's drinking did not show a linear association to BP. In within-center multiple linear regression analysis, relationships between high alcohol intake (much greater than 300 g/week) and BP were assessed among 26 centers with high alcohol drinkers after being adjusted for other confounding variables. Positive associations of high alcohol intake with systolic BP (SBP) and diastolic BP (DBP) were noted in 17 and 16 centers, respectively. Thus, high alcohol intake was positively and independently associated with BP in individual subjects.

Alcohol Drinking↗

PubMed1990

Comparative studies on the relation between nutritional conditions and blood pressure levels of two rural populations with lower incidences of ischemic heart diseases in Japan and Spain.

Comparative studies on nutritional constituents and blood pressure (BP) levels were performed in two rural areas--in Japan (Ohda) and Spain (Navas)--with low incidences of ischemic heart disease. BP levels of both populations were relatively low, probably resulting from potassium- and magnesium-rich Mediterranean diets in Navas and from fish protein-rich Japanese diets in Ohda assessed by 24-h urine analyses according to the World Health Organization (WHO) Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study.

Blood Pressure↗

PubMed1990

Relationship between dietary factors and blood pressure in China. The Sino-Japan CARDIAC Cooperative Research Group.

As part of the international cooperative Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study, we carried out surveys for the relationship of dietary factors to blood pressure (BP) in 10 areas in China, (Altai, Beijing, Guangzhou, Guiyang, Hetian, Lhasa, Shanghai, Shijiazhuang, Tulufan, and Urumqi). Systolic BP and diastolic BP were significantly positively associated with salt excretion and body mass index. However, 3-methylhistidine divided by creatinine, and taurine divided by urea nitrogen in 24-h urine were significantly negatively associated with both BPs. These results suggest that meat protein intake may beneficially influence BP, whereas salt may adversely affect BP.

Blood Pressure↗