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Biomedical subjects

Y Nara

Publications and source records attributed to Y Nara.

At least 181 records · Page 10Linked to original sources
PubMed1986

Morphological and functional differentiation of cultured vascular smooth-muscle cells.

In numerous investigations using cultured smooth-muscle cells, investigators have consistently added 10-20% fetal calf serum (FCS) to the medium to maintain viable cells. In the present study we utilized an optical technique to investigate whether smooth-muscle cells, cultured with or without FCS, maintain their contractile activity in vitro. With such optical measurement, we were able to detect signals due to spontaneous contractions, in muscle cells cultured in FCS-free medium for up to 8 days, and, for the first time, were also able to observe the conduction of these cell contractions. The ultrastructural characteristics of cultured smooth-muscle cells during contractile activity, were also examined by electron microscopy. The cells were mature and well-differentiated, and were packed with numerous myofilaments. They had developed long cell processes, and were linked to one another by gap junctions. These observations indicated that the smooth-muscle cells, cultured without FCS for 7 to 8 days, were morphologically mature and maintained their contractile activity, whereas the cells cultured in FCS-containing medium showed no detectable signs of contractile activity.

Animals↗
PubMed1986

[The electrocardiogram of unanesthetized cats fixed in a net].

Electrocardiograms by standard limb lead, augumented unipolar limb lead and AB (Apex-Base) lead were recorded from 24 unanesthetized adult cats from a SPF closed colony. The unanesthetized cats were held in the sternal position or in the right lateral recumbent position by means of a net. The mean electrical axes of P, QRS and T waves were calculated on the basis of values of I, II and III leads. The ECG patterns and mean electrical axes were compared between the sternal position and the right lateral recumbent position. The results are summarized as follows. The mean values of RR duration, P wave duration, QRS complex duration, T wave duration, PQ interval and QT interval were 0.432, 0.033, 0.027, 0.101, 0.076 and 0.183 seconds, respectively. The values of duration, interval and amplitude were not prominently influenced by the change in posture. The ECG shape had a definite configuration on each lead except that leads I and a VL showed unstable patterns. Notches and R' waves appeared in every lead in many cases. There was a positive linear correlation between RR and QT duration: r = 0.798 in the sternal position and r = 0.525 in the right lateral recumbent position. The angle of QRS mean electrical axis on the horizontal plane was 66.90 degrees +/- 26.05 (SD) in the sternal position and 41.84 degrees +/- 75.23 (SD) in the right lateral recumbent position. The P and T mean electrical axes showed small variations.

Animals↗
PubMed1986

Dietary prevention of stroke and its mechanisms in stroke-prone spontaneously hypertensive rats--preventive effect of dietary fibre and palmitoleic acid.

Previously it was reported that dietary protein, some amino acids and potassium are effective in preventing stroke in stroke-prone spontaneously hypertensive rats (SHRSP). The present study revealed that other dietary factors could also prevent cerebral lesions, and the mechanism of this effect was studied. In SHRSP given 1% NaCl in their drinking water, a diet containing 10% active fibre (powdered brown seaweed converted to K+ form) significantly lowered blood pressure (BP) and markedly reduced the incidence of stroke (0 versus 100% in controls on the 30th day of experiment). Since the faecal to urinary sodium (Na) excretion ratio was increased in this group and a similar increase in faecal Na content was noted in SHRSP given a diet containing 10% alginic acid, the inhibition of intestinal Na absorption by alginic acid in the seaweed fibre was considered to be a possible preventive mechanism. Among SHRSP given various fatty acids, a diet containing 1% palmitoleic acid (POA) significantly improved the survival rate, with concomitant reduction in the incidence of stroke in spite of their excess NaCl intake through 1% NaCl water for drinking. Since neither BP nor urinary Na excretion was changed by POA which had high affinity for the vascular wall, the preventive effect was ascribed to the possible direct metabolic improvement of vascular smooth muscle cells.

Alginates↗
PubMed1985

Angiotensin II and phorbol ester enhance isoproterenol- and vasoactive intestinal peptide (VIP)-induced cyclic AMP accumulation in vascular smooth muscle cells.

The importance of Ca2+ and cAMP in the regulation of cellular functions has been well demonstrated. We studied the effect of angiotensin II (AII), a potent Ca2+-mobilizing hormone, on cAMP accumulation induced by isoproterenol (ISO) and vasoactive intestinal peptide (VIP) in cultured vascular smooth muscle cells (VSMC). Although the addition of AII alone caused little increase of cAMP, it enhanced ISO- and VIP-induced cAMP accumulations in a dose-dependent manner. This enhancement was mimicked by tumor-promoting phorbol ester but not by Ca2+ ionophore. This observation suggested that AII enhanced agonist-induced cAMP accumulation through the activation of protein kinase C in VSMC.

Angiotensin II↗
PubMed1985

Biochemical aspects of salt-induced, pressure-independent left ventricular hypertrophy in rats.

In an attempt to investigate the effect of chronic salt loading on heart size and biochemical composition, sixty 3-month-old male Wistar-Kyoto rats (WKY) were equally divided into two groups: One group was given 1% NaCl in drinking water, and the other group was given tap water as the control. After 7 months, five randomly selected rats from each group were examined for body weight (BW), indirect blood pressure (BP), hematocrit (Hct), and organ weights. Ventricles of the heart, aorta, and mesenteric arteries were biochemically analyzed for collagen (C) and noncollagenous protein NC) and deoxyribonucleic acid (DNA). Although here was no difference between the salt and control groups in BP (129 +/- 3 mmHg vs. 125 +/- 4 mmHg, mean +/- SE), BW (376 +/- 8 g vs. 372 +/- 5 g) and Hct (42.8% +/- 1.0% vs. 44.3% +/- 0.8%), left ventricular weight (857 +/- 19 mg vs. 788 +/- 8 mg) and kidney weight (2.59 +/- 00.9 g vs 2.31 +/- 0.05 g) were both significantly (P less than 0.01) greater in the salt group, whereas the weights of the right ventricle, aorta, and adrenal glands were equal. Biochemical analysis showed significant increase in NC/DNA ratio and total collagen content as well as decreased DNA concentration in the left ventricle of the salt group compared with the control, suggesting hypertrophy rather than hyperplasia of myocardial cells with concomitant activation of collagen synthesis. Since the manner of reactive collagen production appeared different from that reported for spontaneously hypertrophic rats (SHR) or in hypoxia- or aortic constriction-induced cardiac hypertrophy, some unique mechanism may be involved in salt-induced cardiac hypertrophy.

Adrenal Glands↗
PubMed1985

Electronmicroscopic autoradiographic study of the distribution of 3H-diltiazem in myocardial cells.

The distribution of 3H-diltiazem in myocardial cell organelles was studied using an electronmicroscopic autoradiographic technique. At 3, 5 and 10 min after 3H-diltiazem injection, silver grains, which indicate the existence of diltiazem, were detected in plasma membranes and intracellular organelles. Silver grains in T systems were observed more frequently at 3 min than at 5 and 10 min. In contrast, silver grains in sarcoplasmic reticula and mitochondria apparently increased with the passage of time. These findings suggest that diltiazem is transported through the T system and may accumulate within the sarcoplasmic reticula and mitochondria. Furthermore, our study revealed morphologically for the first time that the intracellular sites of action where diltiazem was directed were possibly the mitochondria.

Animals↗
PubMed1985

Comparison of serum phospholipid fatty acids among fishing and farming Japanese populations and American inlanders.

Fatty acid compositions of phospholipids in serum were analyzed in three different populations in seaside fishing and mountain farming villages in Japan and in inland inhabitants of the United States of America. The percentage of omega-3 polyunsaturated fatty acids, i.e., eicosapentaenoic acid (20:5) and docosahexaenoic acid (22:6) was significantly low in United States inlanders with a high coronary heart disease morbidity compared with both populations in Japan with low morbidity. The level of arachidonic acid (20:4) was the same among these three inhabitant population groups. However, omega-3 polyunsaturated fatty acid levels were significantly higher in the inhabitants of fishing villages with relatively low stroke morbidity than in those of farming villages with extremely high stroke morbidity in Japan.

Agriculture↗
PubMed1985

Sympathetic factors in the cardiovascular complications of hypertension: evidence in genetic models for hypertension, stroke and atherosclerosis.

The role of the nervous system in the pathogenesis of cardiovascular complications in hypertension has been clarified to a great extent in genetic rat models for hypertension, stroke and atherosclerosis, especially in the evolution of cardiovascular hypertrophy in hypertension, the most common process related to the pathogenesis and complications of hypertension, in the development of stroke, one of the most common sequelae of hypertension itself and in the pathogenesis of atherosclerotic vascular diseases, the most usual cause of myocardial infarction.

Animals↗
PubMed1985

Crystalline retinopathy: evaluation of blood-retinal barrier by vitreous fluorophotometry.

A 58-year-old man with typical crystalline retinopathy had started complaining of night blindness in both eyes at the age of 56 years. The visual acuity was 0.8 in the right eye and 0.7 in the left eye. Ophthalmoscopic examination showed crystal deposits scattered throughout the posterior pole of the fundus in both eyes. Electroretinogram showed subnormal amplitude and the light-peak/dark-trough ratio of the electrooculogram was reduced. Fluorescein angiography demonstrated atrophy of the pigment epithelium and partial loss of the choriocapillaris in the posterior pole. The crystal deposits were not stained with fluorescein. During the 3-year follow-up period, the crystal deposits coalesced, disappeared and reappeared at new places. Vitreous fluorophotometry was performed in both eyes of this patient. It was found that the rate of fluorescein penetration from the blood into the vitreous was markedly increased and the rate of the dye removal from the vitreous was greatly reduced, as compared to the results in normal subjects. Based on these clinical and fluorophotometric findings, it was concluded that the function of the blood-retinal barrier, particularly of the retinal pigment epithelium, was affected in this disease.

Capillary Permeability↗
PubMed1984

Simple method for sampling consecutive 24-hour urine for epidemiological and clinical studies.

'Aliquot cups' a newly devised tool for collecting 24-hour urine samples were useful and accurate enough for the estimation of individual 24-hour excretion of sodium and potassium. Data from 24-hour collections for 31 days for 5 healthy volunteers showed relatively large intra- and inter-individual variation. These data suggest that at least 5 consecutive days of urine collection would be needed to make a reasonable estimate of daily intake.

Adult↗
PubMed1984

Dietary prevention of hypertension in animal models and its applicability to human.

Experimental studies in animals and epidemiological studies have suggested that the interaction between genetic and environmental factors is important in hypertension associated with excess salt intake and other dietary factors such as K, protein and fatty acid intake greatly modify the effect of salt on blood pressure in individuals with low or high salt sensitivity. Thus, the detection of salt sensitivity and the modification of salt intake as well as other dietary factors are expected to contribute to the primary prevention of cardiovascular diseases associated with hypertension.

Animals↗
PubMed1984

Common cellular disposition to hypertension and atherosclerosis.

The genetically hypertensive rat models, spontaneously hypertensive rats (SHR) and especially stroke-prone SHR (SHRSP), both develop arterial fat deposits quickly when fed high cholesterol diets. Therefore the morphological and functional characteristics of cultured vascular smooth muscle cells (SMC) from the aorta of SHR, SHRSP and normotensive Wistar-Kyoto (WKY) rats have been compared in order to demonstrate the common cellular mechanisms which induce hypertension and atherosclerosis. Cultured SMC became differentiated after short-term foetal calf serum exclusion from the medium, and despite the general concept of their noncontractility there was opticometric evidence that subcultured SMC contract spontaneously. Smooth muscle cells from SHR, but especially from SHRSP, showed enhanced proliferation which was inhibited by a Ca-antagonist, and accelerated lipid incorporation. It is concluded that these SMC are primarily predisposed to hypertension as well as to atherosclerosis.

Animals↗