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Biomedical subjects

J Machida

Publications and source records attributed to J Machida.

At least 19 recordsLinked to original sources
PubMed1992

Effects of phorbol ester on lower urinary tract smooth muscles in rabbits.

The contractile effects of phorbol 12,13-dibutyrate (PDBu) on rabbit urinary bladder dome and urethra were investigated using muscle bath techniques. PDBu caused concentration-dependent contractions in both tissues, and these responses were not affected by pretreatment with atropine, phentolamine, hexamethonium or indomethacin. In both tissues, 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine (H-7), a potent inhibitor of protein kinase C (PKC), inhibited PDBu-induced contractions in a concentration-dependent manner. The maximum PDBu-induced contractions in bladder dome and urethra were 33.5 +/- 3.4 and 33.3 +/- 4.1% of KCl-induced maximum contractions, respectively. In Ca(2+)-free solution or after pretreatment with nifedipine (10(-6) M), PDBu-induced contractions were reduced but not completely abolished. Although pretreatment with PDBu (10(-8) M) did not have a significant effect on the contractile responses induced by carbachol (in bladder dome) and phenylephrine (in urethra), pretreatment with H-7 (100 microM) had an inhibitory effect on carbachol- and phenylephrine-induced contractions; tonic phase contractions were more sensitive than phasic contractions. These results indicate that PDBu has significant contractile effects in rabbit bladder dome and urethra, and that the effects may be partly mediated by activation of PKC. PKC activation might also contribute to agonist-induced contractile responses in these tissues.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Effects of nifedipine on renal cortical and medullary blood flow in two-kidney, one-clip renovascular hypertension in rabbits.

The effects of nifedipine, a calcium antagonist, on blood pressure and renal regional blood flow were investigated in two-kidney, one-clip renovascular hypertensive rabbits. At 1 week after left renal artery constriction, in the constricted group, systemic blood pressure (BP) significantly rose with the elevation of plasma renin activity (PRA). In both kidneys, renal vascular resistance (RVR on the constricted group was significantly increased as compared to that in the control group. In the clipped kidney, total renal blood flow (RBF) and renal cortical blood flow (RCBF) of the constricted group were significantly decreased, while renal medullary blood flow (RMBF) remained at the control value. In the nonclipped kidney, RBF and RCBF of the constricted group did not significantly change, and RMBF was significantly increased as compared to that of the control group. After administration of nifedipine for 1 week (1.0 mg/kg/day), BP in the constricted group was decreased to the control level and PRA in both groups was increased. The percent change of BP in the constricted group was significantly decreased and the percent change of PRA in the constricted group was significantly increased as compared to those in the control group. Nifedipine increased RBF, RCBF and RMBF and decreased RVR of both kidneys in each group. In the nonclipped kidney, the percent change of RBF, RCBF and RMBF of the constricted group was significantly increased and the percent change of RVR was significantly decreased as compared to those of the control group. In the clipped kidney, only the percent change of RBF of the constricted group was significantly lower than that in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Renovascular hypertension. Changes and prognosis of the surgical treatment].

We investigated 663 patients with renovascular hypertension (349 males and 314 females), who were surgically treated at 73 institutions of Urology or Surgery in Japan from 1963 to 1988. There were 294 cases with fibromuscular dysplasia (FMD), 178 with atherosclerosis (SC), 104 with aortitis syndrome (AO) and 87 with other causes. The mean age was 27 years old for FMD, 52 years for SC and 29 years for AO. Thirteen % of FMD, 19% of SC and 38% of AO had stenoses in both renal arteries. Since percutaneous transluminal angioplasty (PTA) has begun in early 1980's, the number of operative cases has been decreased, especially in the case of FMD due to a good result by PTA. Nephrectomy was done in 38% of 704 operations. Aortorenal bypass and autotransplantation were performed in 49% and 26% of the rest, respectively. Recently, autotransplantation has increasingly been applied for complicated vascular lesions. As regards prognosis of the surgical treatment, 77% of FMD, 59% of SC and 50% of AO presented normal blood pressure with or without antihypertensive drugs at least for 10 years after an operation. However, among the patients with normal blood pressure who were observed for more than 5 years, 30% of FMD, 56% of SC and 44% of AO had taken antihypertensive drugs. Eleven patients (1.7% of all) died within one month after the operation, 5 patient of whom had bilateral stenoses. In conclusion, PTA is the first choice for renovascular hypertension and surgery has been done for more difficult and complicated cases in which PTA is ineffective.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Location, classification of histological subtype and rate of lung metastasis in radioactive phosphorus induced rat osteosarcoma: special reference to relation of dosage].

Radioactive phosphorus (P-32) was administered intraperitoneally to Wistar female rats at 2-week intervals. P-32 was administered at a total dose of 3 mCi (a single dose of 200 microCi, 15 times) to Group 1, 2.4 mCi (1 microCi/g body weight, 15 times) to Group 2, and 1.4 mCi (1 microCi/g, 10 times) to Group 3. Osteosarcoma was induced in 29 out of 80 rats (36%) in Group 1, 28 out of 40 (70%) in Group 2, and 31 out of 40 (78%) in Group 3. Bone tumor was predominant in the trunk (spine, ilium etc.) in Group 1 (86%), and in the extremities (femur, tibia etc.) in Group 2 (64%) and Group 3 (71%). Histological findings revealed neoplastic osteoid formation in all lesions. Osteoblastic type developed more in Group 1 than in Group 3, and fibroblastic type developed more in Group 3 than in Group 1. The rate of lung metastasis was significantly higher in Group 3 (94%) than in Group 1 (21%, p less than 0.01) or Group 2 (72%, p less than 0.05). This experimental method, especially that used for Group 3, appears to be useful for studying the basis of human osteosarcoma.

Animals↗
PubMed1989

Effects of caffeine on the vascular smooth muscles isolated from two-kidney, one-clip renovascular hypertension in rabbits.

To examine the intracellular calcium content of the vascular smooth muscle in the chronic phase of renovascular hypertension, the effects of caffeine on isolated aortic, renal and iliac arterial strips were evaluated in two-kidney, one-clip renovascular hypertension in rabbits. 10 weeks after left renal artery constriction in the constricted group, systemic blood pressure (BP) was significantly higher than in the control group, but plasma renin activity was similar to the control value. The amplitude of caffeine-induced contraction of various vascular strips in the constricted group gradually increased and, at 10 weeks, this was higher in the constricted group than in the control group. In the constricted group, sodium loading produced BP elevation and increased the amplitude of caffeine-induced contraction, whereas sodium constriction decreased BP and the amplitude. In the control group, altered sodium intake did not affect BP and the amplitude of caffeine-induced contraction. These results suggest that in the chronic phase of renovascular hypertension, the increased caffeine-sensitive intracellular calcium store on vascular smooth muscle, which is increased by sodium loading and is decreased by sodium restriction, may contribute to the maintenance of hypertension.

Animals↗
PubMed1989

[A rare case of metastasis of the spleen from recurrent cancer of the residual stomach].

In May, 1988, a 75-year-old housewife, who had undergone a subtotal gastrectomy for a carcinoma 12 years earlier, visited our hospital because of vomiting. Biopsy specimens of the residual gastric mucosa revealed malignant cells and an abdominal CT scanning examination showed a solitary nodule in the splenic parenchyma. A non-curative resection of the residual stomach, a splenectomy and a distal pancreatectomy were performed on June 3, 1988. Histological examination of the resected specimens demonstrated a moderately differentiated adenocarcinoma of the stomach, that had invaded the pancreas and retroperitoneal nodes. A nodule of the spleen that was inspected showed a round, greyish solid mass, 0.7 cm in diameter on the cut surface, and microscopically metastatic focus from a gastric cancer. Only a few operated cases manifesting a splenic metastasis of a gastric cancer have been reported and a definitive routing pattern of the metastasis is often difficult to distinguish. However, our case seems to suggest that a hemodynamic route had been taken, since there were no metastatic nodes around the splenic hilus and the metastatic site was only the parenchyma in the spleen.

Adenocarcinoma↗
PubMed1988

Role of sodium and renal prostaglandin E2 in the maintenance of hypertension in the chronic phase of two-kidney one-clip renovascular hypertension in rabbits.

To study the role of sodium and renal prostaglandin E2 in the chronic phase of two-kidney one-clip renovascular hypertension, urinary excretion rates of sodium and prostaglandin E2 were measured in rabbits with hypertension induced by left renal artery constriction during alteration in sodium intake. The arterial blood pressure, the increasing rate of body weight and sodium balance during alteration in sodium intake were directly proportional to the amount of sodium intake in the hypertensive rabbits, but not in the control ones. Plasma renin activity and plasma aldosterone concentration, which had no significant difference between hypertensive and control rabbits, were inversely proportional to the amount of sodium intake in both rabbits. Urinary excretion rates of sodium in the clipped kidneys of the hypertensive rabbits were significantly lower than the control values in all dietary regimens (p less than 0.01). Urinary excretion rates of sodium in the nonclipped kidneys were not significantly higher and in the total kidneys were significantly lower than the corresponding control values during sodium load (p less than 0.01). Urinary excretion rates of prostaglandin E2 were inversely proportional to the amount of sodium intake in both groups. Urinary excretion rates of prostaglandin E2 in the clipped kidneys were significantly lower than the control values in all dietary regimens (p less than 0.001). Urinary excretion rates of prostaglandin E2 in the nonclipped kidneys were significantly higher during sodium restriction (p less than 0.01) but not during sodium load than the control values. Furthermore, urinary excretion rates of prostaglandin E2 in the total kidneys were significantly lower than the control values in all dietary regimens (p less than 0.01). These results suggest that two-kidney one-clip renovascular hypertension in rabbits seems to be partly sodium-dependent in the chronic phase because the nonclipped kidney fails to excrete sodium sufficiently. There may also be disorders of renal prostaglandin E2 metabolism influencing these disorders of sodium in the nonclipped kidneys.

Animals↗
PubMed1987

Human T-cell leukemia virus type I infection in hemodialysis patients.

Human T-cell leukemia virus Type I (HTLV-I) has been detected in a high proportion of individuals in Kumamoto prefecture (Kyushu) and Okinawa, where adult T-cell leukemia (ATL) is more likely to occur. The seroprevalence of antibody to HTLV-I was evaluated in hemodialysis patients and healthy individuals in the ATL endemic area. The prevalence of antibody to HTLV-I in 13,329 healthy controls was 3.6%, compared with 19.7% in 949 chronic hemodialysis patients. The prevalence of hemodialysis patients was significantly higher (P less than 0.01) than that in healthy individuals. Of 681 blood transfused patients who had undergone hemodialysis, 153 (22.5%) were seropositive, compared with 34 (12.7%) of the 268 who had not received the blood transfusion. The incidence was higher in dialysis patients who had been transfused than in those who had never received blood transfusions. Immune defects associated with uremia may have predisposed the patients to HTLV-I infection. Repeated antigenic stimulation from multiple infectious agents may have also played a role. The findings suggest an association between maintenance hemodialysis and HTLV-I infection, which can not be explained solely by blood or blood products.

Adolescent↗
PubMed1987

Effect of adrenergic and cholinergic drugs on the noradrenergic transmission in bladder neck smooth muscle.

Strips of bladder neck smooth muscle were isolated from the dog and noradrenaline stores in the peripheral sympathetic nerve terminals were labelled with (-)3H-noradrenaline. Transmural electrical stimulation was applied and the released radiolabeled noradrenaline in the superfusate was measured with a liquid scintillation counter. Autonomic drugs were administered in the superfusate to examine their effect on noradrenaline release evoked by electrical stimulation. The general conclusions drawn from the data are that: there are two autonomic receptor systems on sympathetic nerve terminals of bladder neck--alpha-adrenergic receptors and muscarinic receptors, the activation of alpha-adrenergic receptors or muscarinic receptors depresses noradrenaline release and parasympathetic nerve excitement inhibits noradrenaline release in bladder neck.

Animals↗
PubMed1987

The change of vascular reactivity to angiotensin II and norepinephrine in the two-kidney, one-clip renovascular hypertensive rabbit.

The change of the response to angiotensin II (AII) and norepinephrine (NE) was evaluated in vivo and vitro in the chronic phase of two-kidney, one-clip renovascular hypertensive rabbits. In the constricted group, systemic blood pressure (BP) was significantly higher and plasma renin activity (PRA) was significantly lower than in the control group. Subpressor doses of AII and NE injections in the constricted group produced significant elevations of BP. In the aortic, renal and iliac arterial strips, the reactivity to AII (10(-10) to 10(-8) M) and NE (10(-10) to 10(-7) M) was significantly increased in the constricted group as compared to the control group. In the constricted group, sodium loading produced BP elevation with decreased PRA and shifted the dose-response curves by AII and NE to the left, whereas sodium restriction decreased BP and shifted the curves to the right. In the control group, altered sodium intake did not affect BP but affected only the dose-response curves by AII. These results suggested that in the chronic phase of renovascular hypertensive rabbits, the increased reactivity to AII and NE may contribute to the maintenance of hypertension.

Angiotensin II↗