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Biomedical subjects

T Saruta

Publications and source records attributed to T Saruta.

At least 433 records · Page 24Linked to original sources
PubMed1989

Effects of endothelin on systemic and renal haemodynamics and neuroendocrine hormones in conscious dogs.

1. The effects of endothelin on systemic and renal haemodynamics and plasma concentrations of neuroendocrine hormones including plasma renin activity, aldosterone, adrenocorticotropic hormone, cortisol, catecholamines and arginine vasopressin were investigated in 18 conscious dogs. 2. Bolus injection of 4 pmol of endothelin/kg did not cause any significant changes in haemodynamics. Mean arterial pressure was elevated by both doses of 40 pmol/kg [91 +/- 2 to 99 +/- 2 mmHg (12.1 +/- 0.3 to 13.2 +/- 0.3 kPa), P less than 0.05] or 200 pmol/kg [93 +/- 2 to 107 +/- 3 mmHg (12.4 +/- 0.3 to 14.3 +/- 0.4 kPa), P less than 0.01], the latter dose increasing cardiac output (14%, P less than 0.05) and heart rate (9%, P less than 0.05), and the former reducing these parameters (14% and 8%, P less than 0.05, respectively). 3. In contrast with the various changes in systemic haemodynamics, renal blood flow transiently increased immediately after bolus injection in a dose-dependent manner (28%, P less than 0.05, 50%, P less than 0.01 and 110%, P less than 0.01 with 4, 40 and 200 pmol of endothelin/kg, respectively). This transient elevation of renal blood flow was followed by a gradual decrease (16%, P less than 0.05; 31%, P less than 0.01 and 36%, P less than 0.01) at 10 min. 4. All neurohormones were elevated in a dose-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1989

Amyloid urinary-tract calculi in patients on chronic dialysis.

Urinary calculi found in 4 patients on chronic hemodialysis or continuous ambulatory peritoneal dialysis (CAPD) were identified as protein calculi by infrared spectroscopic analysis. Positive Congo red staining and immunological assessment revealed that the calculi were composed of amyloid protein derived from beta 2-microglobulin. A comparison of the patients who excreted calculi with 10 patients on chronic dialysis without urinary calculi showed no significant differences in the urinary and serum levels of beta 2-microglobulin. The mechanism of amyloid calculus formation may involve factors independent of the concentration of beta 2-microglobulin in urine or serum. Urinary calculi found in patients on chronic hemodialysis or CAPD were composed of amyloid protein derived from beta 2-microglobulin.

Amyloid↗
PubMed1989

Calcitonin gene-related peptide is an inhibitor of aldosterone secretion.

This study examined the effects of calcitonin gene-related peptide (CGRP) on aldosterone secretion both in vivo and in vitro. Intravenous administration of CGRP (0.01 micrograms/kg) in 6 conscious dogs produced a significant decrease in plasma aldosterone concentration from 68 +/- 12 pg/ml to 28 +/- 11 pg/ml (p less than 0.05) despite a mild but significant elevation of plasma renin activity. In an in vitro study using isolated rabbit adrenal glomerulosa cells CGRP reduced the basal aldosterone secretion in a dose-related manner and furthermore 10(-9) M CGRP inhibited the aldosterone secretion stimulated by 10(-8) M angiotensin II. From these results it is suggested that CGRP has an inhibitory effect on aldosterone secretion.

Aldosterone↗
PubMed1989

The influence of dietary protein on the synthesis of vasoactive substances in subtotally nephrectomized spontaneously hypertensive rats.

The effects of dietary protein alterations on the synthesis of prostaglandins and kallikrein were examined in subtotally nephrectomized spontaneously hypertensive rats. Three diets containing 40, 24 and 8% protein were prepared. After subtotal nephrectomy, rats were given one of the three diets for the next 12 weeks. During the study, systolic blood pressure, urinary excretions of protein, 6-keto-prostaglandin F1 alpha, thromboxane B2 and kallikrein were measured every 2 weeks. Although the diets did not prevent the further elevation of systolic blood pressure, the rats on the low protein diet displayed lower serum creatinine levels and urinary protein levels. The urinary excretion of thromboxane B2 was unaffected by the amount of dietary protein, but the urinary excretion of 6-keto-prostaglandin F1 alpha was lower in the low protein diet group. Furthermore, the urinary excretion of kallikrein increased significantly in rats on high protein diet. These results suggest that manipulation of dietary protein may alter the natural course of renal failure induced by subtotal nephrectomy in spontaneously hypertensive rats.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Increased sympathetic nerve activity at home in young subjects with hypertension.

Plasma and urine norepinephrine, epinephrine, plasma renin activity and aldosterone were measured in 11 young men (mean age, 21 years) with a high blood pressure in the clinic who maintained a high home blood pressure and 12 men with an elevated clinic blood pressure who had a normal home blood pressure. Plasma samples were drawn following 30 min rest in the clinic, and 24-hour urine samples were collected at home. The two groups of hypertensives could not be distinguished on the basis of clinic blood pressure, plasma norepinephrine, epinephrine, renin activity or aldosterone. Patients with a high home blood pressure were characterized by a high urinary norepinephrine excretion. These results suggest that the patients whose blood pressure remained elevated at home had an increased sympathetic nerve activity at home.

Adolescent↗
PubMed1989

Captopril therapy following percutaneous transluminal angioplasty for bilateral renal artery stenosis.

To establish an optimal approach for the patients with bilateral atherosclerotic renal artery stenosis, combined treatment involving percutaneous transluminal renal angioplasty and oral captopril was applied. Five patients were examined for effects of the combined treatment on blood pressure and renal function. After percutaneous transluminal renal angioplasty on one renal artery, the blood pressure (mean +/- SD) fell from 210/118 +/- 26/8 to 176/104 +/- 11/9 mm Hg without any deterioration of renal function. This reduced blood pressure was further lowered to 155/92 +/- 6/3 mm Hg by adding captopril therapy. This level of blood pressure has been maintained for an average of 37 months. Significant increases in serum creatinine concentration were not observed (124 +/- 27 vs 141 +/- 44 mumol/L), and renal size has been sustained. These results indicate that combined treatment with percutaneous transluminal renal angioplasty and captopril is effective in reducing the blood pressure and preserving renal function as an approach for the patients with bilateral atherosclerotic renal artery stenosis.

Aged↗
PubMed1989

Insulin autoantibodies in mouse models of insulin-dependent diabetes.

To clarify the significance of insulin autoantibodies (IAA) in insulin-dependent diabetes mellitus, we measured the IAA longitudinally in non-obese diabetic (NOD) mice, and in high-dose streptozotocin-induced diabetes (high-SZ) and EMC virus-induced diabetes (EMC) in mice, and compared the data with the occurrence of insulitis. The IAA were detected by the polyethylene glycol (PEG) method using 125I-(Tyr A14) human insulin. The IAA were found in 38% of NOD mice and correlated with the occurrence of insulitis. The prevalence of IAA was 0% before the appearance of insulitis, 80% at 12-14 weeks of age and 30% after 20 weeks of age in female NOD mice. In male NOD mice, IAA were found in 45% at 12-14 weeks of age and 20% after 20 weeks. In high-SZ mice, IAA were detected in several mice while insulitis was not present. In EMC-virus induced diabetic mice, IAA and lymphocytic infiltration into the islets were detected 4-14 days after EMC virus infection. These results suggest that (a) IAA are markers for islet autoimmunity in NOD mice, (b) the presence of IAA does not always reflect insulitis, (c) the presence of IAA is not sufficient for the development of overt diabetes and (d) the appearance of IAA may reflect a difference of the immune response genotype.

Animals↗
PubMed1989

[Klebsiella pneumoniae meningitis associated with liver abscess: a case report].

We report a rare case of Klebsiella pneumoniae meningitis associated with liver abscess, which was successfully treated with cefotaxime (CTX), one of the third-generation cephalosporins. A 53-year-old man was admitted to Keio University Hospital on June 13, 1988, because of a fever and a headache. On June 3, he suddenly started shivering and his temperature rose to 39 degrees C. He then began to complain of polydipsia, polyuria, and a weight loss of 4 kg a week. On June 11, he developed a severe headache. Four years prior to this incident, he had been diagnosed as having diabetes after a routine medical examination, but had neglected to undergo medical treatment. On admission, laboratory data showed leukocytosis, hyperglycemia (394 mg/dl) and ketonuria (4+). A lumbar puncture yielded cloudy cerebrospinal fluid (CSF) containing 500/3 cells/mm8, of which about 70% were neutrophils. A diagnosis of diabetic ketoacidosis and purulent meningitis was made. A treatment with ampicillin (ABPC) and CTX, (12 g/day, each) was begun. On the third day, cultures of a blood specimen and CSF yielded both K. pneumoniae. The MICs of CTX to K. pneumoniae isolated from blood and CSF were both 0.05 microgram/ml. ABPC was discontinued, gentamicin was administered for 2 days, CTX was continued at the same dosage level and an administration of prednisolone 40 mg daily was begun.(ABSTRACT TRUNCATED AT 250 WORDS)

Cefotaxime↗
PubMed1989

Effects of streptozotocin-induced diabetes on glucose utilization that was stimulated by various agents in rat thymocytes.

Post receptor insulin resistance has been demonstrated in insulin sensitive tissues from streptozotocin induced diabetic animals. Insulin deficiency itself or metabolic derangements of diabetes seem to contribute to this insulin resistant state. However, the mechanism is presently unknown. Using largely insulin insensitive rat thymocytes, we have studied glucose oxidation stimulated by agents that mimic insulin action but that work independently of the insulin receptor. Glucose oxidations stimulated by these agents were markedly diminished in the thymocytes from streptozotocin induced diabetic rats. These findings as well as our finding that the thymocytes from diabetic rats possess a normal complement of insulin receptor provide further evidence that post insulin receptor impairment of glucose metabolism occurs in streptozotocin diabetes. Thus although thymocytes are not sensitive to insulin, they are useful for the investigation of the impaired glucose metabolism.

Animals↗
PubMed1989

The suppressive effect of cyclophosphamide on low-dose streptozotocin-induced diabetes in mice.

We found that low-dose streptozotocin (SZ)-induced diabetes in mice is suppressed by cyclophosphamide (CY) and studied the mechanisms of this suppression. Male CD-1 mice were injected intraperitoneally with SZ (40 mg/kg) for five consecutive days (group SZ). In addition, CY (200 mg/kg) was injected on the first day (group CY-1) or on days 1 and 5 (group CY-2). In group SZ, all mice developed diabetes within nine days after the first injection of SZ. Group CY-1 did not develop hyperglycemia for 14 days and group CY-2 did not develop it throughout the experimental period (40 days). Insulitis was suppressed slightly in group CY-1 and completely in group CY-2. The number of spleen cells did not change in group SZ compared with that before cyclophosphamide treatment. They decreased significantly on days 3 and 7 in both groups CY-1 and CY-2 (p less than 0.01 or p less than 0.05), but then increased significantly on days 14 and/or 21 (p less than 0.01 or p less than 0.05) compared with those before cyclophosphamide treatment. The Thy 1.2- and L3T4-positive cells increased significantly in group SZ but they decreased on days 3 and 7 in both groups CY-1 and CY-2 (p less than 0.01) compared with the controls. These results suggest that (1) this large reduction of lymphocytes at the beginning of SZ treatment may lead to the prevention of hyperglycemia and insulitis, and (2) T-cells, especially L3T4-positive cells may play an important role in the pathogenesis of this type of diabetes.

Animals↗
PubMed1989

Spontaneous rupture of the quadriceps tendon in patients on maintenance hemodialysis--report of three cases with clinicopathological observations.

Three patients receiving maintenance hemodialysis therapy for end-stage renal failure presented with spontaneous rupture of the quadriceps tendon(s). Biochemical data and the skeletal roentgenograms were compatible with secondary hyperparathyroidism. Histological examination of the excised quadriceps tendon specimens suggested that repeated minor avulsion fractures of the bone cortex at the tendon insertion site had preceded the final total tendon rupture and that osteitis fibrosa was responsible for these minor fractures. Serum alkaline phosphatase level had been increasing continuously for approximately five years prior to the tendon rupture in all three patients, indicating that uncontrolled osteitis fibrosa due to secondary hyperparathyroidism over these years preceded the tendon rupture.

Adult↗
PubMed1989

[Therapeutic guide for renovascular hypertension with reevaluation of surgical treatment].

Therapeutic guide for renovascular hypertension has been greatly changed by a development of beta-blockers and captopril, and an introduction of percutaneous transluminal angioplasty (PTA) The accepted opinion was that surgical therapy was superior to drug therapy since Hunt & Strong reported the follow-up results in 1973. However, efficacy of drug therapy was reevaluated by an appearance of beta-blockers and captopril and the number of patients applied to operation was decreased. Further, since PTA was widely used in clinical practice from the end of 1970s, surgical therapy for renovascular hypertension was hardly or never considered. Has the necessity of surgical therapy really ceased to exist? Recently, we encountered 2 cases of bilateral renovascular hypertension and reevaluated the necessity of surgical therapy during the course of treatment. The first case was in a 43-year-old male, for whose bilateral renovascular stenosis a bilateral PTA was applied. One year later a complete occlusion of the right renal artery and re-stenosis of the left renal artery developed. Thus, removal of the right kidney and the auto-transplantation of the left kidney were conducted. The second case was in a 17-year-old female with bilateral renovascular stenosis complicated by moya-moya disease. PTA was conducted for the left kidney with shorter range of stenosis and auto-transplantation was conducted for the right kidney with longer range of stenosis. The prognosis was favorable in both cases and hypertension was cured or improved. We recognized and re-evaluated the necessity of surgical therapy for patients who were unsuccessful to PTA or patients with bilateral renovascular hypertension from our experience and literatures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

[Antiarrhythmic agent caused marked hypoglycemia in a patient receiving hemodialysis: relation with disopyramide and verapamil].

A 70-year-old man with a 5-year history of hemodialysis was admitted to Keio University Hospital due to severe constipation on March 27, 1986. He recognized constipation and abdominal distention one month before admission, and his general condition became gradually worse. After the admission, a barium enema revealed obstruction at the upper portion of the ascending colon. A righ colectomy was successfully performed on April 8. Before the operation he showed frequent premature ventricular beats on his ECGs, but after the operation atrial fibrillation with rapid ventricular responses appeared. The arrhythmia was normalized with the intravenous administration of verapamil and disopyramide and oral administration of those drugs was continued. A few weeks later he was found to be drowsy occasionally. His fasting plasma glucose was revealed to be 29 mg/dl. After the discontinuation of the antiarrhythmic agents his plasma glucose level returned to normal. To see what role disopyramide might play in this hypoglycemic phenomenon, oral glucose tolerance tests were done before and during the administration of disopyramide. The examination revealed stimulation of insulin secretion by disopyramide.

Aged↗
PubMed1988

Bile acids are able to reduce blood pressure by attenuating the vascular reactivity in spontaneously hypertensive rats.

Effects of the synthetic bile acids on blood pressure were examined in spontaneously hypertensive rats. Continuous intravenous administration of the bile acids at the rate of 1 mg/min for 20 min significantly lowered the blood pressure by 12 mmHg. In order to examine its blood pressure lowering mechanism, the isolated mesenteric arterial perfusion system was employed. Bile acids in the perfusate inhibited vascular reactivity to norepinephrine and KCl in a dose-dependent manner. This inhibitory action diminished as the concentration of potassium in the perfusate decreased. When the perfusate was free from potassium, its inhibitory action completely disappeared. These results in vivo and in vitro studies strongly suggest that bile acids act directly on the vascular beds and attenuate vascular response to norepinephrine.

Animals↗
PubMed1988

Cardiovascular effects of intravenous and intracoronary administration of atrial natriuretic peptide in halothane anesthetized dogs.

Cardiovascular actions of synthetic 1-28 human natriuretic peptides (hANP) were examined in dogs anesthetized with halothane. In seven closed-chest dogs a Swan-Ganz catheter was inserted for measurement of cardiac output. Intravenous infusion of increasing doses of hANP (0.1, 0.3, 0.9 microgram/kg/min) lowered mean aortic pressure without affecting heart rate significantly. Cardiac output and pulmonary wedge pressure were markedly decreased while total peripheral resistance was increased significantly. All these parameters returned to control levels after 1 hr of recovery with an 100-150ml of saline infusion to increase pulmonary capillary wedge pressure to the preinfusion value. Intracoronary infusion of hANP (0.05 and 0.1 microgram/kg/min) did not cause any significant changes in coronary flow and regional contraction. These results indicate that the hypotensive action of hANP is due to a decrease in cardiac output mediated by reduced preload but not by negative inotropic action.

Anesthesia↗
PubMed1988

Effects of first-line antihypertensive agents on sexual function and sex hormones.

We studied sexual dysfunction induced by antihypertensive agents in 156 male hypertensive patients. The antihypertensive agents were: trichloromethiazide, 2-4 mg; atenolol, 50-100 mg; captopril 37.5-75 mg; and slow release nifedipine 40-80 mg, administered every day for 1 year after a 2-4-week placebo period. Sexual dysfunction was checked by both a self-reporting questionnaire and a test for serum sex hormones. In the self-reporting questionnaire, the following items were requested: reduction of sexual desire, problems in obtaining and maintaining an erection, problems in ejaculation and the number of occasions of sexual intercourse. The sex hormones measured were testosterone, follicular stimulating hormone, luteinizing hormone and oestradiol. During the placebo period, 5% of the hypertensive patients complained of some sexual disturbance without any significant changes in the plasma levels of the sex hormones. In the short term (1-4 weeks) after the initiation of the antihypertensive therapy, all antihypertensive agents except captopril caused sexual dysfunction. Patients on atenolol or trichloromethiazide complained of every item listed. Those on slow-release nifedipine complained mainly about problems in ejaculation. Serum levels of both testosterone and follicular stimulating hormone were significantly decreased while there was mild elevation of oestradiol in patients on atenolol. In the long term (1 year), only patients taking atenolol experienced sexual dysfunction and mild reduction of serum levels of testosterone. Our findings show that first-line antihypertensive agents have different effects on sexual function and that only captopril may have some advantages over the other agents in terms of the quality of sexual life.

Adult↗