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S Niimura

Publications and source records attributed to S Niimura.

At least 19 recordsLinked to original sources
PubMed2000

The effect of docarpamine, a dopamine pro-drug, on blood pressure and catecholamine levels in spontaneously hypertensive rats.

We studied the effects of bolus intravenous injection of the dopamine prodrug, docarpamine (200 microg/kg), on mean arterial pressure (MAP) and heart rate (HR) in Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHRs). In WKY rats (n=18), MAP and HR increased 5 min after docarpamine and then returned to baseline levels within 15 min. In contrast, in SHRs (n=15), MAP and HR gradually decreased, reaching a nadir 20 min after injection. Five min after docarpamine, plasma dopamine and 3,4-dihydroxy phenyl acetic (DOPAC) levels increased in both WKY rats (n=5) and SHRs (n=5). The docarpamine-induced changes in MAP and HR in both rat strains (n=5/strain) were blocked by the D1-like antagonist, SCH23390. alpha-Adrenergic (n=4) and vasopressin V1 (n=3) receptor blockade also abrogated the effects of docarpamine in WKY rats. We conclude that docarpamine differentially affects MAP and HR in WKY and SHRs. In SHRs, the depressor and bradycardiac effects of docarpamine are mediated by D1-like receptors. In WKY rats, the pressor and tachycardiac responses are caused by an interaction among D1-like, alpha-adrenergic, and V1 receptors.

Adrenergic alpha-Antagonists↗
PubMed1995

Postprandial changes in noradrenergic and dopaminergic activity in patients with essential hypertension.

In order to elucidate the role of noradrenergic and dopaminergic activity in the pathogenesis of postprandial hypotension, the effect of feeding of ordinary diet on blood pressure, pulse rate, plasma catecholamine and other circulating vasoactive substances such as insulin were examined in mild essential hypertensive patients (EH) and their age-matched control subjects (N). Mean blood pressure significantly decreased in both N and EH after feeding, and the decrease tended to be greater in EH than in N. Feeding induced a marked increase in plasma norepinephrine in both N and EH. Plasma dopamine significantly increased following feeding was observed in N, while the increase in plasma dopamine following feeding was blunted in EH. The ratio of norepinephrine to dopamine following in EH was significantly greater than that in N. From these results, it is suggested that the feeding-induced stimulation of noradrenergic activity may be a result from the decrease in blood pressure, and that the blunted response of dopaminergic activity in EH may reflect the enhanced conversion of dopamine to norepinephrine probably due to the enhanced activity of dopamine beta-hydroxylase in the sympathetic nerves.

Blood Pressure↗
PubMed1994

[A case of idiopathic hyperaldosteronism with normal plasma aldosterone concentrations for 5 years after onset: a 12-year follow-up study].

We report a 54-year old man diagnosed as idiopathic hyperaldosteronism (IHA) at least 12 years after the onset. At the age of 42, he showed hypertension (162/100mmHg), hypokalemia, metabolic alkalosis, low plasma renin activity (PRA) and normal plasma aldosterone concentration (PAC) in a supine posture. Both PRA and PAC were elevated after a 2-hour ambulation following furosemide (60mg) injection. Since the accumulation of radioactivity following 131I-aldosterol injection with combined administration of dexamethasone was equally detected in both adrenal areas, he was diagnosed as low-renin essential hypertension (LREH). Blood pressure (BP) decreased to the normal range after treatment with nifedipine (40mg/day). At the age of 47, however, BP was hypertensive (164/106mmHg) serum potassium (K) level was normal. Although PAC was normal in a supine posture, it increased after a 2-hour ambulation following furosemide (60mg) injection. PRA after the stimulation was still suppressed despite the increase in PAC. At the age of 54, BP was 172/94mmHg. Serum K level was 3.4mEq/L. PRA was suppressed below 0.1 ng/ml/hr, while PAC was above the normal range (170pg/ml) in a supine posture. Serum cortisol and urinary excretion of 17-OHCS and 17-KS were within normal limits. PRA was still suppressed below 0.1 ng/ml/hr after a 2-hour ambulation following furosemide (60mg) injection, but PAC was markedly increased (330pg/ml). There was a diurnal rhythm of aldosterone, which was parallel to that of ACTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1994

TCV-116, a newly developed angiotensin II receptor antagonist, induces regression of cardiac hypertrophy through suppression of the tissue renin-angiotensin system in spontaneously hypertensive rats.

Previously, we reported that an orally active angiotensin II (Ang II) receptor antagonist Losartan induces regression of left ventricular hypertrophy with reduction in the tissue Ang II contents in spontaneously hypertensive rats (SHR). To further address the role of the cardiac renin-angiotensin system in the pathophysiology of hypertensive left ventricular hypertrophy, we examined the effects of TCV-116, a newly developed, highly specific nonpeptide Ang II receptor antagonist, on cardiac hypertrophy and the tissue angiotensin I (Ang I) and Ang II, as well as plasma renin activity (PRA) and Ang II, were determined. Treatment with TCV-116 (1 mg/kg per day) lowered blood pressure markedly. TCV-116 reduced significantly the left ventricular weight by about 11% compared with control animals. The left ventricular Ang I and Ang II contents were lowered by TCV-116 (12.9 +/- 1.4 vs. 30.4 +/- 2.5 pg/tissue, control, p < 0.01, for Ang I; 15.1 +/- 0.6 vs. 18.7 +/- 0.4 pg/tissue, control, p < 0.01, for Ang II), whereas PRA and plasma Ang II concentration were increased by the treatment. With the control and TCV-116-treated animals, there was a significant positive correlation between the left ventricular weight and the tissue Ang II content (r = 0.681, p < 0.01). These results not only further support the view that cardiac Ang II, rather than circulating Ang II, plays an important role in the pathophysiology of left ventricular hypertrophy of this animal model of human hypertension, but imply also that TCV-116 induces regression of hypertensive left ventricular hypertrophy through suppression of the tissue renin-angiotensin system.

Angiotensin I↗
PubMed1994

[Clinical study on ivermectin against 125 strongyloidiasis patients].

We treated 125 patients with strongyloidiasis (78 males and 47 females) by 2 oral doses of ivermectin (6 mg) at 2-week interval, and obtained the following results: 1. Eradication rate after treatment was 86.4% (108 of 125 patients), responsively. Out of the total 17 patients were resistant (non-responsive) to treatment, 8 patients received a further course of ivermectin and all Strongyloides stercoralis in their feces were eradicated. 2. Side effects were observed in 7.2% of the patients after the first dose treatment and in 3.2% after the second dose. But all symptoms were mild and self-limited. Although liver disfunction developed in 13.6% of the patients, no symptoms occurred and no special treatment was required. 3. Positive rate of anti-HTLV-I antibody in the resistant group was significantly higher (80.0%) than in the eradicated group (29.2%) and in the stool-negative group (0%). 4. Although eosinophils before treatment in the eradicated group was significantly higher than that of controls, there was no significant difference between the resistant group and controls. IgE levels in the resistant group was significantly lower than in the eradicated group. We would like to conclude that IVM is the best drug for treatment of the patient with Strongyloides stercoralis not only from this results but also our previous reports which had investigated the clinical efficacy on thiabendazole, mebendazole and albendazole.

Adult↗
PubMed1993

Congenital nephrogenic diabetes insipidus in an adult.

A 35-year-old man with congenital nephrogenic diabetes insipidus (NDI) is reported. Renal biopsy revealed miniaturized and rounded mitochondria of the proximal tubular cells and decreased brush-borders. Trichlormethiazide combined with triamterene resulted in an apparent reduction of daily urine volume and concomitant increment in urine osmolarity. The present case seems rare in that some morphological changes in the renal tissues could be demonstrated in an adult case with congenital NDI.

Adult↗
PubMed1992

[A case of insulinoma with frequent hypoglycemic attacks not showing evident hyperinsulinemia].

Confirmation of inappropriate hyperinsulinemia is an indispensable requisite for the diagnosis of insulinoma. We report here a case of insulinoma without evident hyperinsulinemia at an early stage. The patient, a 49-year-old woman, had been admitted to our hospital for the evaluation of frequent hypoglycemic attacks. At that time, plasma immunoreactive insulin (IRI) after an overnight fast ranged from 7 to 16 microU/ml. The ratio of IRI/fasting blood sugar (FBS) (Fajans index; normal range, below 0.3) was always between 0.13 and 0.28 even at hypoglycemic states. In addition, because computed tomography and arteriography of the abdomen failed to settle the diagnosis of insulinoma, the patient was discharged and followed up at our outpatient clinic for 2 years. She was admitted to our hospital at 51 years of age for the re-evaluation of hypoglycemic attacks. Laboratory examinations revealed high fasting plasma levels of IRI ranging from 20 to 29 microU/ml. Fajans index also increased to 0.47-0.89. Celiac arteriography was able to confirm the existence of insulinoma. We suggest that insulinoma should be considered in the presence of unexplained hypoglycemic attacks even when there is no evident hyperinsulinemia.

Blood Glucose↗
PubMed1992

Antihypertensive and hormonal activity of MK 954 in spontaneously hypertensive rats.

MK 954 (DuP 753), a recently developed angiotensin II (Ang II) receptor antagonist, was administered orally for 2 weeks to spontaneously hypertensive (SHR) and Wistar-Kyoto rats (WKY). Whereas the basal levels of plasma Ang II were lower in SHR than in WKY, treatment with MK 954 markedly reduced blood pressure in SHR but not in WKY. Plasma renin activity, Ang I and Ang II were increased, while plasma aldosterone was decreased in both strains. These results no only indicate therapeutic efficacy of this agent in the chronic treatment of human hypertension, but also support the idea that the renin-angiotensin system plays an important role in the control of blood pressure in SHR.

Angiotensin I↗
PubMed1992

Losartan, a specific angiotensin II receptor antagonist, increases angiotensin I and angiotensin II release from isolated rat hind legs: evidence for locally regulated renin-angiotensin system in vascular tissue.

The effect of Losartan (10(-9) to 10(-6) M) on angiotensins I and II release was examined in isolated hind legs perfused with Krebs-Ringer solution from normal and bilaterally nephrectomized rats. Losartan increased dramatically both angiotensins I (Ang I) and II (Ang II) release in a dose-dependent fashion; the maximal percent increment in Ang I and Ang II release evoked by Losartan (10(-6) M) was about +380% and +160%, respectively, in normal rat hind legs. In nephrectomized animals, Losartan elicited a marked increase in both peptides dose-dependently. There was a highly positive correlation between the released amounts of Ang I and that of Ang II altered by Losartan in either normal (r = 0.954) or nephrectomized rats (r = 0.923). These results not only confirm the existence of a functional renin-angiotensin system in vascular tissues, but also suggest that the system is regulated by locally generated Ang II.

Angiotensin I↗
PubMed1992

Effects of losartan, a nonpeptide angiotensin II receptor antagonist, on cardiac hypertrophy and the tissue angiotensin II content in spontaneously hypertensive rats.

Losartan, a recently developed nonpeptide angiotensin II (Ang II) receptor antagonist, was administered orally to 10-week-old spontaneously hypertensive rats (SHR) for 2 weeks. Cardiac weight and tissue Ang II, as well as plasma renin activity (PRA) and Ang II, were determined. Treatment with Losartan (10 mg/kg per day) lowered blood pressure markedly. Losartan reduced significantly the left ventricular weight by 11% compared with control rats. The left ventricular Ang II content was lowered by Losartan (18.6 +/- 0.9 pg/tissue; 21.9 +/- 0.9 pg/tissue, control, p less than 0.05), whereas PRA and plasma Ang II concentration were increased by the treatment. With the control and Losartan-treated animals, there was a significant positive correlation between the left ventricular weight and the tissue Ang II content (r = 0.563, p less than 0.05). These results provide evidence that cardiac tissue Ang II, rather than circulating Ang II, plays an important role in the pathophysiology of left ventricular hypertrophy of this animal model of human hypertension.

Analysis of Variance↗
PubMed1992

Hypotensive activity of TCV-116, a newly developed angiotensin II receptor antagonist, in spontaneously hypertensive rats.

TCV-116, a recently developed angiotensin II (Ang II) receptor antagonist, was administered orally (1 mg/kg per day) to 10-week-old spontaneously hypertensive rats (SHR) for 2 weeks. Blood pressure and plasma components of the renin-angiotensin-aldosterone system were determined in these rats. TCV-116 produced a marked reduction in blood pressure without altering heart rate. Whereas plasma renin concentration (PRC), angiotensin I (Ang I) and angiotensin II (Ang II) all were significantly increased, plasma aldosterone was decreased by approximately 70% compared with control animals. These results not only indicate therapeutic efficacy of this agent in the chronic treatment of human hypertension, but support also the concept that the renin-angiotensin system plays an important role in the control of blood pressure in this animal model of human essential hypertension.

Angiotensin Receptor Antagonists↗
PubMed1992

[Clinical study of albendazole therapy for strongyloidiasis].

We reported the efficacy of albendazole (ABZ) for the treatment of 27 patients with strongyloidiasis. Twenty-seven patients, 23 males and 4 females, received 200 mg of ABZ one hour before breakfast and supper for 3 days and this treatment was repeated 2 weeks later. The following results were obtained: 1) The eradication rate at 2 weeks after the initial treatment was 70.4% (19 of 27 patients) and 2 weeks after the second course was 66.7% (16 of 24 patients). 2) One patients (3.7%) complained of abdominal pain after the first treatment. Four patients (14.8%) complained of headache (n = 2), nausea (n = 1) and exanthema (n = 1) after the second treatment. But all symptoms were mild and required no treatment and subsided in a few days. 3) Positive rate of HTLV-1 antibody was 45.8% in the patients. As described above, side effects occurred in some cases, although they were mild and transient. From these results, it can be concluded that on increased dose of ABZ could be much more favorable for the treatment of strongyloidiasis.

Adult↗
PubMed1992

[Clinical study on symptoms in patients with strongyloidiasis].

We treated strongyloidiasis patients and obtained the following results: Of the 299 patients (184 males and 115 females), 81 patients (27.1%) had no complaints before treatment, 218 patients complaints of some symptoms, including arthralgia and/or lumbago (28.4%), abdominal pain and/or borborygmus (19.3%), numbness of extremities (18.1%), constipation (16.3%) and itching (15.7). We treated 219 patients with mebendazole and symptoms improved after treatment described below: Thirty-seven of the 63 patients (58.7%) with arthralgia and/or lumbago improved. Twenty-seven of the 36 patients (75.0%) with numbness of extremities improved. Thirty-one of the 32 patients (96.9%) with heartburn improved. We treated 26 patients with mebendazole plus thiabendazole and twelve of 14 patients (85.7%) with abdominal pain and/or borborygmus were improved after treatment. We treated 54 patients with ivermectin and five of 18 patients (27.8%) with arthralgia and/or lumbago were improved after treatment.

Adult↗
PubMed1992

[Long term eradication rate of mebendazole therapy for strongyloidiasis].

We treated 245 strongyloidiasis patients with 7 schedules of mebendazole (MBZ) and obtained the eradication rates at 8 months to 2 years after the final treatment as described follows; MBZ (100 mg) was given twice a day orally. [Square bracket shows incidence of liver disfunction.] 1) The eradication rates at 2 years after single course of MBZ therapy for 28 days and a combination therapy (thiabendazole 500 mg powder form three times daily for 5 days followed by MBZ in powder form for 9 days, repeated once) were 93.8% (15 of 16 patients), [71.4%] and 100.0% (16/16), [50.0%]. 2) The eradication rates at 8-15 months after using MBZ alone in varying dosages were as follows: a) MBZ powder was administered for 5 days and was then repeated 1, 3 and 4 weeks later: 87.1 (27/31), [51.1%]. b) MBZ powder was given for 5 days and repeated 1 and 3 weeks later: 100.0% (7/7), [30.8%]. c) MBZ powder was administered for 4 days and repeated 1, 3 and 4 weeks later: 96.3% (26/27), [57.8%]. d) MBZ in tablet form was given for 4 days and repeated 1, 3 and 4 weeks later: 89.6% (43/48). [66.2%]. e) MBZ in tablet form was administered for 4 days and repeated 1 week later: 69.2% (9/13), [25.0%]. As described above, although the incidence of liver disfunction in the 4-day with 2-course therapy was lower than the other schedules, the eradication rate was lower. From these results, MBZ should be given to strongylodiasis patient for 4 days and repeated once, or for 3 days and repeated two or three times with 1 to 2 weeks intervals.

Adult↗
PubMed1992

[Clinical study of eradicated and resistant patients to treatment with ivermectin for strongyloidiasis].

We treated 70 patients with strongyloidiasis (41 males and 29 females) with ivermectin (IVM), and obtained the following results: 1. The eradication rates at 1-2 months, 3-4 months and 5-6 months after treatment were 90.7% (49 of 54 patients), 100.0% (47 of 47 patients) and 95.7% (45 of 47 patients), responsively. Twelve patients were resistant (non-responsive) to treatment. 2. When compared to patients whose parasites were completely eradicated, the resistant patients showed the following results: 1) Incidence of symptoms observed before treatment was significantly lower (50.0% vs. 84.5%). 2) Positive rate of anti-HTLV-I antibody was significantly higher (66.7% vs. 20.7%). 3) Blood eosinophil counts before treatment were significantly lower (266.6 +/- 117.2/mm3 vs. 533.2 +/- 429.7/mm3). 4) Serum IgE levels before treatment were significantly lower (217.2 +/- 442.9 IU/ml vs. 1,076.8 +/- 2,108.0 IU/ml). 5) There were no significant differences in age, sex and dosage of ivermectin. 3. Comparing anti-HTLV-I antibody positive and negative patients, the following results were obtained: 1) Eradicated patients; a) Eosinophils and IgE levels before and after the first administration of medicine in anti-HTLV-I antibody positive patients were significantly lower than those of negative patients. b) Gammaglobulin levels before treatment and after both administrations of the drug, IgG before therapy and OKT4/OKT8 after therapy were significantly higher than in anti-HTLV-I antibody positive patients. 2) Resistant patients; Eosinophils after treatment were significantly lower in anti-HTLV-I antibody negative patients than in positive patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗