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Biomedical subjects

T Saruta

Publications and source records attributed to T Saruta.

At least 289 records · Page 16Linked to original sources
PubMed1994

Expression and distribution of aquaporin of collecting duct are regulated by vasopressin V2 receptor in rat kidney.

To examine whether expression and distribution of aquaporin of collecting duct (AQP-CD) are regulated by vasopressin V2 receptor (V2R), we performed immunohistochemical studies with specific antibody against AQP-CD. Normal Wistar rats were divided into four groups and treated for 3 d; control, dehydration, vasopressin V1 receptor (V1R) antagonist (OPC-21268 120 mg/kg), V2R antagonist (OPC-31260 30 mg/kg). At time of death, urine osmolality (Uosm) in the dehydration group (1884 +/- 245 mOsm/kg) was significantly higher than that in the control (938 +/- 91). In the V2R antagonist group, Uosm was significantly decreased to 249 +/- 29, whereas V1R antagonist showed no effect on Uosm. In the control and V1R antagonist groups, immunofluorescence studies showed the AQP-CD staining of both apical membrane and subapical cytoplasm of CD cells of the cortex and the inner medulla. Dehydration increased the immunostaining of both apical membrane and subapical cytoplasm of CD cells of the inner medulla, and the degree of increase was dominant in apical membrane. In the V2R antagonist group, only faint staining of apical membrane and weak labeling of cytoplasm of CD cells of the inner medulla were observed. These changes in the localization and protein amount of AQP-CD by dehydration and V2R antagonist were quantitatively confirmed by immunogold studies and immunoblot analysis of the inner medulla. The present results indicate that the distribution and amount of AQP-CD in the CD cells are regulated by vasopressin V2 receptor.

Animals↗
PubMed1994

Circulatory and plasma catecholamine responses to mental stress in young subjects with two different types of hypertension.

To determine whether any differences exist between young male subjects with elevated diastolic and systolic blood pressure (BP) and those with only an elevated systolic BP, the responses of BP and plasma catecholamines to a mental arithmetic test were studied in 11 young men (mean age of nineteen years) with BP of > or = 140/90 mm Hg at a routine health check-up (group I-hypertension [HT]), 26 age-matched men with only elevated systolic BP (> or = 140 mm Hg) (group II-HT), and 12 age-matched normotensive (NT) men (< 140/90 mm Hg). During an arithmetic test, group I-HT showed a significantly higher increment of systolic BP (+14.5-18.0%) than group II-HT (+9.3-10.2%) and NT controls (+6.4-8.2%). However, no significant difference in BP response was seen between group II-HT and NT controls. Plasma norepinephrine in group I-HT showed a significant increase after the test, (171 +/- 23-->202 +/- 27 pg/mL), whereas group II-HT and NT controls showed no change. No significant difference occurred in epinephrine response among the three groups. These results suggest that the young male subjects with screening BP above 140/90 mm Hg are hyperreactive to a mental stress as compared with subjects with only elevated systolic BP or NT controls.

Adult↗
PubMed1994

Steroid contents and cortical steroidogenic enzymes in non-hyperfunctioning adrenal adenoma.

The recent increasing use of ultrasound and computed tomography has revealed numbers of incidentally discovered adrenal tumors. Many studies have focused on their surgical management, but the biological characteristics of these adrenal tumors have remained unclear. Adrenal tumors were resected from 10 patients who underwent gastrectomy or cholecystectomy. No signs or symptoms of adrenal hormone excess or deficiency were evident either before or after the operation. Moreover, after surgery, no major differences in signs and symptoms including blood pressure levels were observed. Before surgery, neurogenic tumors and cysts were excluded by enhanced magnetic resonance imaging. Steroid contents and both the activities and amounts of steroidogenic cytochrome P-450s in the adrenocortical adenomas of these patients were examined. Microscopic examination revealed that the tumors were surrounded by a thin, non-intact capsule; the surrounding cortex was not atrophic and apparently normal; and the cells of both the tumor and adjacent portions were arranged in nests and cords. Measurements of all steroid content (pregnenolone, progesterone, corticosterone, 11-deoxycorticosterone, 18-hydroxydeoxycorticosterone, cortisol, and dehydroepiandrosterone) except aldosterone in 5 resected adrenal tumors were within the normal ranges for the adrenals of 5 patients with renal cell carcinoma. Aldosterone content in tumor portions was significantly lower than in the apparently normal adrenals. Although in both tumor and adjacent portions of another 5 resected adrenal tumors the activities and amounts of cytochrome P-450s (P-450scc, P-450(11 beta), P-450aldo, P-450(17 alpha), and P-450c21) were also within the normal ranges, the activities of P-450scc and P-450(17 alpha) in the tumor portion were greater than those in the adjacent portion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex Neoplasms↗
PubMed1994

Acquired idiopathic pure red cell aplasia in a hemodialyzed patient with inactive systemic lupus erythematosus.

A male patient suffered chronic renal failure due to lupus nephritis and was undergoing hemodialysis. Six years after beginning hemodialysis, anemia developed, which improved by erythropoietin. Unresponsiveness to erythropoietin gradually appeared, and with a suspicion of pure red cell aplasia, he was treated with a high-dose corticosteroid but the unresponsiveness did not improve. Neither his serum nor lymphocytes inhibited erythropoiesis of either normal bone marrow stem cells or his own in vitro. These observations suggest an impaired hematopoietic microenvironment in his bone marrow.

Adrenal Cortex Hormones↗
PubMed1994

Addison's disease in Japan: characteristics and changes revealed in a nationwide survey.

Patients with Addison's disease, newly diagnosed in the last five years were surveyed nationwide in conjunction with two past surveys. The decreasing incidence, i.e., 168 patients from 1977 to 1981 (survey 1), 108 from 1982 to 1986 (survey 2), and 74 from 1987 to 1991 (the present survey), reflects a decrease in the incidence (n = 28) of tuberculous Addison's disease, but not that (n = 36) of idiopathic Addison's, making the idiopathic form predominant for the first time in the history of the disease in Japan. Because the interval between the preceding tuberculosis and the onset of Addison's averages 32 +/- 15 years, tuberculous Addison's has a relatively late onset. Pigmentation is the most frequent symptom (90%). Other symptoms, abnormal laboratory data, and positive adrenal antibodies are observed less frequently in Japan than in North America or Europe. The types of associated disorders are also distributed differently. Adrenal CT and MRI scans have been the most useful means in differentiating between the two major types of the disease. This report focuses on features distinguishing Japanese sufferers from their western counterparts.

Addison Disease↗
PubMed1994

Radioimmunoassay detects the frequent occurrence of autoantibodies to the Mr 65,000 isoform of glutamic acid decarboxylase in Japanese insulin-dependent diabetes.

Glutamic acid decarboxylase antibodies (GAD65Ab) are common in new onset Caucasian insulin-dependent diabetic (IDDM) patients but it is unclear if this marker is also prevalent in patients of other ethnic backgrounds. We determined antibodies against human recombinant GAD in Japanese diabetic patients using a radioimmunoassay with competition between in vitro translated 35S-GAD65 and non-labelled recombinant human GAD65 (rhGAD65). GAD67 antibodies (GAD67Ab) were similarly analyzed but without antigen competition. In 73 Japanese diabetic patients, GAD65Ab were found in 11/16 (69%) of patients with short-duration (less than 5 yrs) IDDM, 6/23 (26%) with long-duration (5 or more yrs) IDDM and 10/20 (50%) with slowly progressive diabetes. High GAD65Ab levels were associated with concomitant autoimmune diseases (p = 0.021). GAD67Ab were found in 4/16 (25%) of patients with short-duration IDDM, 3/23 (13%) with long-duration IDDM and 2/20 (10%) with slowly progressive diabetes. In 14 non-insulin dependent diabetic (NIDDM) patients, GAD65Ab and GAD67Ab were not found (0/14) and 1/50 (2%) healthy controls were positive in either assay. Among the GAD67Ab-positive samples, 8/9 (88%) were also high level GAD65Ab positive, 7/9 (77%) were displaced by an excess of rhGAD65 and the antibody levels correlated (r2 = 0.573; p = 0.003). Our data are consistent with a strong association of GAD65Ab also in Japanese IDDM, and suggest that, when present, GAD67Ab are frequently directed to epitope(s) common to GAD65 and GAD67.

Asian People↗
PubMed1994

Increased urinary dopamine excretion in young patients with essential hypertension.

The evidence that some older patients with essential hypertension have low urinary dopamine excretion has brought into question the levels of urinary dopamine and plasma dopa, the major source of urinary dopamine, in young patients with essential hypertension. Twenty-four-hour urine sodium, creatinine, dopamine and noradrenaline and plasma dopa were evaluated in 48 patients with essential hypertension aged 18 to 27 years and 25 normotensive subjects. In comparison with age-matched normotensive subjects, the hypertensive patients had higher urinary dopamine (1920 +/- 80 vs 1520 +/- 130 nmol/day, p < 0.01) and noradrenaline (216 +/- 11 vs 179 +/- 12 nmol/day, p < 0.05) excretion. There was a significant correlation between urinary dopamine and noradrenaline excretion. There was no difference in plasma dopa levels between normotensive and hypertensive subjects. These results suggest that the elevated conversion of dopa to dopamine in the kidney is leading to increased urinary dopamine excretion in young patients with essential hypertension.

Adult↗
PubMed1994

Effects of a calcium channel blocker, nicardipine, on pressure-natriuresis in Dahl salt-sensitive rats.

The effects of a calcium channel blocker, nicardipine, on pressure-natriuresis responses were studied in Dahl salt sensitive (DS) and resistant (DR) rats. Differences in the neural and endocrine background were minimized by renal denervation and by holding plasma vasopressin, aldosterone, corticosterone, and norepinephrine levels constant by intravenous infusion. The renal plasma flow (RPF) and glomerular filtration rate (GFR) of DS rats were disautoregulated in the low renal perfusion pressure range, while those of DR rats were autoregulated. Administration of nicardipine (0.3 microgram/kg/min) into the renal artery significantly increased RPF and GFR and abolished the autoregulation in both strains of rats. Nicardipine also sharpened the pressure-natriuresis responses in both strains without changes in fractional excretion of sodium. These findings suggest that nicardipine increased GFR and thereby improved the pressure-natriuresis responses of DS rats.

Animals↗
PubMed1994

Role of glucocorticoid in the development of glycyrrhizin-induced hypertension.

Role of alterations of corticosterone metabolism in the expression of the mineralocorticoid activity of glycyrrhizin was explored in rats. While the mineralocorticoid actions of oral glycyrrhizin were not observed in bilaterally adrenalectomized rats and dexamethasone treated rats, the mineralocorticoid actions of glycyrrhizin were fully expressed in bilaterally adrenalectomized rats supplemented with physiological doses of corticosterone. Similar mineralocorticoid actions were observed in rats given glycyrrhizin, deoxycorticosterone and pharmacological doses of corticosterone. Although increases in mean blood pressure were suppressed only by concurrent administration of spironolactone to glycyrrhizin- and deoxycorticosterone-treated rats, increases in mean blood pressure were attenuated by both the glucocorticoid antagonist RU 38486 and spironolactone in pharmacological doses of corticosterone administered rats. Pressor responses to norepinephrine and angiotensin II infusions in rats given deoxycorticosterone and pharmacological doses of corticosterone were significantly higher than in glycyrrhizin-treated rats. These results confirmed the functional significance of 11-beta-hydroxysteroid dehydrogenase in expression of the mineralocorticoid activity of glycyrrhizin.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1994

Renal protective effects of amlodipine on partially nephrectomized spontaneously hypertensive rats fed a high-salt diet.

We examined the effects of a calcium-channel blocker amlodipine on progression of renal failure in 5 of 6 nephrectomized spontaneously hypertensive rats (SHR) fed a high-salt diet. Twelve SHR, 5 of 6 with nephrectomy and salt-loading, were divided into two group: group 1 as control (n = 6) and group 2 treated with 2 mg/kg/day amlodipine (n = 6). During the 10 study weeks, body weight, systolic blood pressure (SBP), and daily urinary protein excretion were measured every 2 weeks. At the end of the study, serum creatinine, urea nitrogen, and total protein and albumin were determined. Renal tissues were obtained for light microscopic examination. The increase in SBP after 10 study weeks was significantly less in the treated group than in the control group (control 287 +/- 5 mm Hg; amlodipine 237 +/- 23 mm Hg (p < 0.01)). Urinary protein excretion was also suppressed in the amlodipine-treated group (p < 0.01). Although in the control group glomerular sclerosis and hyalinosis were marked, they were significantly less in the amlodipine-treated group. These results illustrate that amlodipine can attenuate BP increase and inhibit progression of hypertensive renal injury in this rat model.

Amlodipine↗
PubMed1994

Angiotensin II type 1 receptor messenger RNA levels in human blood cells of patients with primary and secondary hypertension: reference to renin profile.

OBJECTIVES: The relationship between plasma renin activity, plasma angiotensin II (Ang II) or aldosterone levels and peripheral blood cells (mononuclear leucocytes and platelets) Ang II type 1 (AT1) receptor messenger RNA (mRNA) levels were examined in both primary and secondary hypertensive patients. DESIGN AND METHODS: The subjects were 30 patients with primary hypertension, five with primary aldosteronism, five with renovascular hypertension and five normotensive controls with renal cell carcinoma. Blood was collected from each patient for estimation of plasma renin activity and plasma Ang II and aldosterone concentrations, and for isolation of mononuclear leucocytes and platelets, which were then used to measure AT1 receptor mRNA with reverse-transcription polymerase chain reaction. RESULTS: Platelet AT1 receptor mRNA levels were inversely correlated with plasma Ang II levels, and mononuclear leucocyte receptor mRNA levels were positively correlated with plasma Ang II levels in patients with primary hypertension. In contrast, in secondary hypertension both platelets and mononuclear leucocytes AT1 receptor mRNA, which were elevated, were reduced after removal of the adrenal tumour or correction of stenosis of the renal artery. CONCLUSIONS: Platelet AT1 receptors, which were used to reflect physiologically important sites such as vascular smooth muscle, were shown to be regulated in a different manner from mononuclear leucocyte receptors. In patients with primary aldosteronism and renovascular hypertension the plasma aldosterone level was shown to be an important factor upregulating AT1 receptor mRNA.

Adrenal Glands↗
PubMed1994

Open clinical studies on a new angiotensin II receptor antagonist, TCV 116.

OBJECTIVES: The goals of these preliminary studies were to evaluate the effects of a new angiotensin II receptor antagonist, TCV 116, on the daytime blood pressure profile in hospital inpatients with essential hypertension, and to evaluate the clinical efficacy and safety of this agent in outpatients with essential hypertension. SUBJECTS: In study 1, daytime blood pressure changes were studied in 28 inpatients with mild to moderate essential hypertension (systolic blood pressure > or = 150 mmHg, diastolic blood pressure > or = 90 mmHg). In study 2, 55 outpatients with essential hypertension (systolic blood pressure > or = 160 mmHg, diastolic blood pressure > or = 95 mmHg) were enrolled in a dose-finding study. METHODS: In study 1, after a 1-week placebo run-in period, blood pressure and the pulse rate were measured every 2 h except at night. TCV 116 monotherapy was started at 1 mg/day and increased stepwise at 3- to 5-day intervals to 2, 4 and 8 mg/day until a predetermined reduction in blood pressure was achieved. The daytime profiles of blood pressure and the pulse rate were again monitored at the end of the treatment period. In study 2, after a 4-week placebo run-in period, TCV 116 alone was administered for 2 weeks at 1 mg/day. The dose was then increased to 2 mg/day and stepwise at 2-week intervals to 4 and 8 mg/day until a predetermined reduction in blood pressure was achieved. The total treatment period was 8-12 weeks. RESULTS: In study 1, a sufficient reduction in blood pressure was achieved in 19 of 28 patients (68%), with blood pressure significantly reduced at all measurement points, compared with the placebo run-in period. No differences were seen in the pulse rate. The only adverse reaction reported was a rash in one patient. In study 2, a sufficient reduction in blood pressure was achieved in 42 out of 55 patients (76%). The cumulative efficacy rate increased dose-dependently (15% at 1 mg/day, 38% at 2 mg/day, 60% at 4 mg/day and 76% at 8 mg/day). No differences were seen in the pulse rate. Adverse reactions were reported in three out of 55 patients (5.5%). No dry cough was reported by any of the patients. CONCLUSIONS: TCV 116, an angiotensin II receptor antagonist, has potential as an antihypertensive agent. A dose of 4-8 mg once per day appears to be appropriate for the treatment of patients with mild to moderate essential hypertension.

Benzimidazoles↗
PubMed1994

Nonpeptide angiotensin II type 1 receptor antagonist prevents nephrosclerosis in hypertensive rats.

Angiotensin II (AII) appears essential in remnant kidney models of renal injury in rats, and renal injury was reduced by angiotensin-converting enzyme inhibitor (ACEI). To determine whether this is due to AII blockade or other actions of ACEI, we studied a nonpeptide AII type 1 receptor antagonist and an ACEI in partially nephrectomised spontaneously hypertensive rats (SHR). Thirty SHR underwent surgery and were divided into three equal groups: Control, TCV (0.5 mg/kg/day TCV-116), and CAP (30 mg/kg/day captopril). All SHR received a 5%-NaCl diet. Systolic blood pressure (SBP) and urinary protein were measured at 2-week intervals. Serum total protein, albumin, urea nitrogen, and creatinine were determined at week 8. Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured at weeks 4 and 8. Renal injury was evaluated histopathologically. TCV and CAP reduced SBP at week 2 and proteinuria at week 8. GFR and RBF fell in all groups, but decreases were not significant in treated SHR and histopathological changes were significantly ameliorated. All blockade by TCV or CAP reduces renal injury in salt-loaded SHR with partial renal ablation. AII is essential in remnant kidney models of renal injury, and AII blockade is essential in renal protection by ACEI.

Angiotensin Receptor Antagonists↗
PubMed1994

Relation of home blood pressure to body weight in young normotensive men with or without family history of hypertension.

We investigated the relation between home blood pressure (BP) and body weight in 38 young normotensive men (mean age, 16 years) whose parents were normotensive (PNT group) and 34 age- and sex-matched normotensive men, one or both of whose parents were hypertensive (PHT group). Although causal BP measurements were similar in both groups, home systolic BP was significantly higher in the PHT group (123 +/- 1 mm Hg) than in the PNT group (116 +/- 1 mm Hg). Body weight was significantly greater in the PHT group (66.0 +/- 1.4 v 61.8 +/- 1.3 kg, P < .05) and body mass index (BMI) was not significantly higher in the PHT group (22.4 +/- 0.5 v 21.3 +/- 0.5 kg/m2, P = .09). Body weight (r = 0.38) and BMI (r = 0.42) were significantly correlated with home systolic BP in the PHT group. There were no differences in serum lipid or uric acid concentrations between the two groups. Our results showed that young normotensive subjects with a genetic predisposition to hypertension weighed more and had higher home systolic BPs compared with subjects without a family history of hypertension. Our observations further indicated a close relationship between a family history of hypertension and increased body weight, even in young normotensive men.

Adolescent↗
PubMed1994

Increased expression of vascular angiotensin II type 1A receptor gene in glucocorticoid-induced hypertension.

OBJECTIVES: We recently demonstrated that glucocorticoid increases the number of angiotensin II type 1 (AT1) receptors and their gene expression in cultured vascular smooth muscle cells. To clarify whether this mechanism participates in glucocorticoid-induced hypertension, we investigated the effect of dexamethasone on the modulation of vascular AT1 receptor messenger RNA (mRNA) expression in rats. METHODS: The effects were studied of administering dexamethasone orally to rats at a dose of 0.1 mg/day on the modulation of the expression of vascular AT1 receptor mRNA and the blood pressure. The effects of enalapril maleate, an angiotensin converting enzyme inhibitor, were also evaluated. RESULTS: The dexamethasone-treated rats showed a rise in systolic blood pressure beginning on day 3. On day 5 the blood pressure rose significantly. Before dexamethasone administration the vascular AT1 receptor mRNA was difficult to detect by Northern blot analysis. However, the level of vascular AT1A receptor mRNA began to increase on day 2, when the blood pressure was not yet elevated, and increased further on day 5. The concurrent administration of dexamethasone and enalapril maleate attenuated the elevation of blood pressure. However, as in the dexamethasone-treated rats, the level of AT1A receptor mRNA began to increase on day 2 and increased further on day 5. In rats treated with enalapril maleate alone, the AT1 receptor mRNA was difficult to detect during the experiment. CONCLUSION: Glucocorticoid increased the amount of vascular AT1 receptor mRNA and contributed to the elevation of blood pressure.

Animals↗
PubMed1994

Hypertension in thyroid disorders.

Hypertension is more common in hypothyroidic patients than in euthyroid controls in older age groups. Treatment of the thyroid deficiency alone lowers blood pressure in most patients. Hemodynamically, cardiac output is reduced and total peripheral resistance is elevated. The latter probably is secondary to an increase of sympathetic nervous tone and a relative increase in alpha-adrenergic response. In hyperthyroidism, elevation of diastolic blood pressure is uncommon. Systolic hypertension is more common in younger age groups. Treatment of the hyperthyroidism alone lowers systolic blood pressure in most patients. An increase in cardiac output and a decrease in total peripheral resistance accompany the hyperthyroidism. Potentiation of catecholamine action by an excess of thyroid hormone has been invoked as an explanation, because thyroid hormone excess is accompanied by increased beta-adrenergic receptors in some tissue, including heart.

Humans↗
PubMed1994

Idiopathic progressive glomerulopathy with extensive subendothelial and mesangial immune deposit formation.

A 32-year-old Japanese male presented with abundant proteinuria, and renal biopsy revealed diffuse subendothelial and mesangial deposits in the glomeruli without hypercellularity or mesangial interposition. There was no clinical or laboratory evidence of systemic conditions such as collagen-vascular disease, paraproteinemia, or infection. Treatment with corticosteroid was ineffective and the patient eventually went into end-stage renal failure. To our knowledge, this is the first report of an idiopathic progressive glomerulopathy characterized by diffuse, global subendothelial and mesangial deposits, which suggests to us a novel insight into glomerular subendothelial/mesangial deposition.

Adult↗