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Biomedical subjects

S Murabayashi

Publications and source records attributed to S Murabayashi.

At least 19 recordsLinked to original sources
PubMed1992

Acute effect of an alpha 1-adrenoceptor antagonist on urinary sodium excretion, plasma atrial natriuretic peptide, arginine vasopressin, and the renin-aldosterone system in healthy subjects.

To elucidate the mechanism underlying the sodium retention caused by alpha 1-adrenoceptor blockade in man, a placebo-controlled, randomised, double-blind study has been made of the acute effects of bunazosin an alpha 1-antagonist, on urinary sodium excretion, atrial natriuretic peptide (ANP), arginine vasopressin (AVP), and the renin-aldosterone system in 7 healthy men. A single oral dose of bunazosin 2.0 mg caused a significant reduction (P less than 0.05) in urinary sodium excretion after 0-2 h, 2-4 h, and 4-6 h. The mean values for plasma ANP, AVP, aldosterone, and cortisol concentrations at those times were similar after placebo and bunazosin, and plasma renin activity was significantly increased 2 and 4 h after bunazosin. Pretreatment with oral enalapril 10 mg, an angiotensin converting enzyme inhibitor, did not prevent the bunazosin-induced reduction in urinary sodium excretion. There was a significant positive correlation between the drug-induced changes in blood pressure and urinary sodium excretion. The results suggest that ANP, AVP, and renin-aldosterone may play little role in the sodium retention caused by acute alpha 1-adrenoceptor blockade in man.

Adrenergic alpha-Antagonists↗
PubMed1990

Comparison of the renal effects of dilevalol and carteolol in patients with mild to moderate essential hypertension.

The effects of 6 weeks of treatment with dilevalol 100 mg once daily, or carteolol 10 mg once daily, on renal blood flow (RBF), glomerular filtration rate (GFR) and total renal vascular resistance (TRR) were studied in 10 patients with mild-to-moderate essential hypertension in a randomised cross-over experiment. Both drugs lowered the systolic and diastolic blood pressures to a similar extent without altering the heart rate. Carteolol non-significantly decreased RBF by 9.2% and GFR by 12.3% without altering. TRR, whereas dilevalol produced a significant reduction in TRR by 13.2% (p less than 0.05), a non-significant decrease in RBF by 4.6% and no change in GFR. Neither drug changed plasma osmotic pressure, serum total protein concentration, electrolytes or plasma aldosterone concentration. Plasma renin activity tended to be lower in the dilevalol phase as compared to the carteolol phase. The results suggest that dilevalol may cause a greater decrease in TRR and less reduction in GFR when compared to carteolol in patients with mild-to-moderate essential hypertension. The difference in the renal effects might be due to the difference in the potency of vasodilatory properties of both drugs at the doses applied.

Adult↗
PubMed1990

Renal effects of nicardipine, a calcium antagonist, in hypertensive type 2 (non-insulin-dependent) diabetic patients with and without nephropathy.

The renal effects of oral maintenance doses of nicardipine 60-120 mg/day have been studied in 18 hypertensive patients with Type 2 (non-insulin-dependent) diabetes mellitus: 6 with normoalbuminuria (urinary albumin excretion rate, AER less than 20 micrograms.min-1, Group A); 6 with incipient nephropathy, (AER 20-200 micrograms.min-1, Group B); and 6 with overt nephropathy (AER greater than 200 micrograms.min-1, Group C). Treatment for 4 weeks significantly lowered the systolic and diastolic blood pressures and reduced total renal vascular resistance in all three groups. Nicardipine increased renal blood flow significantly in Group C and slightly in Group B, and had no effect in Group A. Glomerular filtration rate remained unchanged in all three groups. It significantly reduced AER and the fractional clearance of albumin in Group B, whereas AER in Groups A and C was not altered. Plasma renin activity, aldosterone concentration, osmotic pressure, serum total protein and albumin concentrations and haemoglobin A1c level were similar in the control and nicardipine phases in all three groups. The results suggest that nicardipine may preserve renal function whilst having a concomitant hypotensive action in hypertensive Type 2 diabetic patients with normoalbuminuria and incipient nephropathy, and that the drug may improve renal blood flow in patients with overt nephropathy. The effect of the drug on urinary albumin excretion may deserve further investigation.

Albuminuria↗
PubMed1990

Renal effects of bunazosin, a new alpha 1-adrenoceptor blocker, in patients with mild-to-moderate essential hypertension.

Renal effects of 4-week fixed maintenance doses of bunazosin three times daily (2.0 mg t.i.d., n = 8) and propranolol (40 mg t.i.d., n = 8) were evaluated in patients with mild-to-moderate essential hypertension [World Health Organization (WHO) stages I and II]. Both bunazosin and propranolol decreased blood pressure (BP) significantly (p less than 0.05), but the magnitude of reduction in diastolic BP (DBP) was greater with bunazosin (p less than 0.05) than with propranolol. Bunazosin produced a nonsignificant increase in renal blood flow (RBF) by 14%, a significant increase in glomerular filtration rate (GFR) 11% (p less than 0.05), and a decrease in total renal vascular resistance (TRR) by 15% (p less than 0.05), whereas propranolol caused no significant changes in these parameters. Urinary sodium excretion rate and the fractional excretion of sodium were unchanged by either of the drugs. The results of this short-term study suggest that bunazosin may be a drug that will increase RBF and GFR and decrease TRR with a concomitant hypotensive action in patients with mild-to-moderate essential hypertension. Whether these renal functional effects of the drug would benefit such patients must be determined in long-term studies.

Adrenergic alpha-Antagonists↗
PubMed1990

The pharmacokinetics of enalapril in patients with compensated liver cirrhosis.

The possibility of an impaired hepatic de-esterification of enalapril to enalaprilat due to hepatic dysfunction was assessed in seven patients with compensated liver cirrhosis and 10 normal control subjects. The peak serum concentration and time to the peak serum concentration of enalaprilat, as well as the suppression of serum angiotensin converting enzyme activity, following a single oral dose of enalapril maleate (10 mg) were not different in the two groups. The elimination half-life of enalaprilat was related to renal function. The results suggest that hepatic biotransformation of the drug may not be disturbed in a clinically significant manner in patients with moderate hepatic dysfunction due to compensated liver cirrhosis.

Adult↗
PubMed1990

Uncontrolled hypertension is associated with a rapid progression of nephropathy in type 2 diabetic patients with proteinuria and preserved renal function.

The relationship between blood pressure and progression of nephropathy was studied (the mean follow-up period of 32.6 +/- 17.9 (S.D.) months in 20 Type 2 (non-insulin-dependent) diabetic patients with clinical nephropathy (proteinuria greater than 0.5 g/day) and preserved renal function (serum creatinine level less than 150 mumol/liter). Fifteen hypertensive patients under antihypertensive treatment were divided into 2 groups: those with the mean diastolic blood pressure greater than or equal to 90 mmHg and/or the mean systolic blood pressure greater than or equal to 150 mmHg during the follow-up period were designated as Group A (n = 6) and the remainders as Group B (n = 9). Five normotensive patients without any anti-hypertensive treatment throughout the follow-up period served as a control group (Group C). The decline rate in GFR was significantly greater (p less than 0.05) in Group A (1.15 +/- 0.39 (S.E.) ml/min/month) than those in Groups B (0.33 +/- 0.08 ml/min/month) and C (0.40 +/- 0.09 ml/min/month), respectively. The decline rate in GFR showed significant positive correlations both with systolic (rS = 0.553, p less than 0.05) and diastolic (rS = 0.493, p less than 0.05) blood pressures in the 15 hypertensive patients. The age, initial glomerular filtration rate, duration of diabetes and mean HbA1c level during the observation period were comparable in Groups A, B and C, respectively. The results indicate that an uncontrolled hypertension is associated with a rapid progression of kidney impairment in Type 2 diabetic patients with overt nephropathy, as has been suggested in Type 1 (insulin-dependent) diabetic patients.

Adult↗
PubMed1990

Effect of anticoagulant on biocompatibility in membrane plasmapheresis.

The effect of heparin or citrate anticoagulation on blood cellular, complement pathway and coagulation pathway was investigated in a membrane plasma exchange procedure. Two membrane plasma separators constructed of cellulose di-acetate (CA) and polyvinyl chloride (PVC) were evaluated with heparin or citrate alone for anticoagulation in a 26 year old male with myasthenia gravis. Maximum white blood cell counts decrease was 21% at 30 min for the CA with heparin while no decrease was observed for the other schemes. Platelet counts changes were comparable between heparin and citrate, while the PVC groups showed less changes than the CA groups. The CA groups, regardless of the type of anticoagulant used, indicated that complement activation occurred via the classical pathway within the module in addition to the activation via alternative pathway for the CA with heparin. In the PVC groups, complement activation was noted to occur only when heparin was used for anticoagulation. PT and PTT showed slight increases with citrate, while they were remarkably prolonged with heparin. Citrate showed less changes in cellular and humoral factors compared to heparin. CA with heparin was the most activating combination of membrane material and anticoagulant, while the PVC with citrate was the least activating combination.

Adult↗
PubMed1989

Comparison of the renal effects of angiotensin converting enzyme inhibitor and calcium antagonist in hypertensive type 2 (non-insulin-dependent) diabetic patients with microalbuminuria: a randomised controlled trial.

Seven of eight hypertensive Type 2 (non-insulin-dependent) diabetic patients with microalbuminuria completed a randomised crossover trial to compare the renal effects of angiotensin converting enzyme inhibitor (enalapril) and calcium antagonist (nicardipine). Four-week fixed oral maintenance dosages of enalapril (10-20 mg/day) and nicardipine (60-120 mg/day) significantly (p less than 0.05) lowered the systolic and diastolic blood pressures without altering renal blood flow, glomerular filtration rate and filtration fraction. Both drugs significantly reduced (p less than 0.05) urinary albumin excretion rate and fractional clearance of albumin to similar extents. Total renal vascular resistance decreased significantly by nicardipine (p less than 0.05) and non-significantly by enalapril. Plasma osmotic pressure, plasma aldosterone concentration, total serum protein concentration, serum electrolytes and HbA1c remained unchanged by these drugs, whereas plasma renin activity was significantly higher (p less than 0.05) in the enalapril than in the control and nicardipine phases. These results suggest that both drugs have similar renal function preserving effects with a concomitant hypotensive action in hypertensive Type 2 diabetic patients with microalbuminuria, and that the angiotensin converting enzyme inhibitor may not have advantageous renal effects when compared to the calcium antagonist and vice versa. Both drugs might be useful for treatment of high blood pressure in hypertensive diabetic patients, if long-term studies of these drugs can be shown to benefit the patients over other conventional antihypertensive therapies.

Aged↗
PubMed1989

Urinary dopamine, noradrenaline and adrenaline in type 2 diabetic patients with and without nephropathy.

We measured the urinary excretions of dopamine, noradrenaline and adrenaline, their conjugated metabolites, urinary excretion of sodium and creatinine clearance simultaneously in 21 patients with Type 2 (non-insulin-dependent) diabetes and 6 normal subjects. The mean (+/- SEM) value for urinary excretion of dopamine (52.4 +/- 8.8 micrograms/day) in diabetic patients with nephropathy (Group C, n = 12) was significantly lower (P less than 0.01) than in the normal subjects (Group A, 179.7 +/- 15.5 micrograms/day) and in diabetic patients without nephropathy (Group B, n = 9, 131.5 +/- 16.5 micrograms/day). The mean values for the urinary excretions of noradrenaline and adrenaline were also significantly lower (P less than 0.01) in Group C than in Groups A and B. In addition, the mean urinary excretion of conjugated metabolite of dopamine in Group C was significantly lower (P less than 0.05) than in Group A. There was a trend toward the observation that the mean 24-h urinary excretion of sodium in Group C (121.6 less than 12.9 mEq) was lower as compared with that in Group A (140.8 +/- 8.9 mEq) or B (150.7 +/- 17.9 mEq). A multiple regression analysis revealed that the 24-h urinary excretion of dopamine correlated significantly with creatinine clearance, systolic (P less than 0.01) and diastolic (P less than 0.05) blood pressures. The results indicate that synthesis or secretion of renal dopamine might decrease with a progression of diabetic nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Creatinine↗
PubMed1988

Effects of dilevalol, an R, R-isomer of labetalol, on blood pressure and renal function in patients with mild-to-moderate essential hypertension.

The effects of oral dilevalol (an R, R-isomer of labetalol), a new beta-adrenoceptor blocker with beta 2-receptor stimulating and alpha-recepter blocking properties on blood pressure, renal function, plasma renin activity (PRA) and plasma aldosterone have been studied in 15 patients with mild-to-moderate essential hypertension treated with it for 6 weeks. Two patients with apparent treatment failure and one patient who developed muscle pain and cramps, and had an elevated creatine phosphokinase level, were excluded from the study. Dilevalol monotherapy 100 mg once daily for 6 weeks significantly lowered both the systolic and diastolic blood pressure compared to placebo. Total renal vascular resistance was significantly reduced, and RBF and GFR remained unchanged. Dilevalol significantly decreased PRA. The results suggest that prolonged daily treatment with dilevalol preserves renal function and produces a concomitant hypotensive action in patients with mild-to-moderate essential hypertension. The ancillary pharmacological properties of dilevalol rather than PRA suppression may be relevant to its renal effects.

Adrenergic beta-Antagonists↗
PubMed1988

Spontaneous remission of acromegaly after pituitary apoplexy following head trauma.

A 34-year-old man with acromegaly was observed, and the clinical course and various endocrinological deficiencies occurring before, during and after the development of pituitary apoplexy were evaluated. Following the attack, the patient experienced acute reductions in growth hormone (GH) and other pituitary hormones, adrenohypophyseal insufficiency and transient diabetes insipidus which appeared subsequent to glucocorticoid therapy. The level of growth hormone in serum and cerebrospinal fluid (CSF) was measured synchronously, and the respective regressions of GH levels in serum and CSF were observed. The results demonstrated the utility of measuring hormonal levels in CSF in the clinical evaluation of pituitary apoplexy in a patient with a functioning pituitary tumor.

Acromegaly↗
PubMed1988

Effect of cimetidine on the pharmacokinetics and pharmacodynamics of enalapril in normal volunteers.

The possible effects of cimetidine on the pharmacokinetics and pharmacodynamics of enalapril, a pro-drug requiring hepatic de-esterification to an active angiotensin-converting enzyme (ACE) inhibitor enalaprilat, were assessed in a randomized, crossover study. Cimetidine (400 mg) or placebo was administered orally every 12 h for 3 days and on the day of a single oral administration of enalapril maleate (10 mg) to seven healthy male subjects. Serum ACE, plasma renin activity (PRA), plasma aldosterone concentration (PAC), and alpha-human atrial natriuretic peptide (alpha-hANP) were measured before and 4 h after the enalapril dosing. There were no significant differences in any serum- and urine-derived kinetic parameters of enalapril and enalaprilat, nor in hemodynamics, PAC, or alpha-hANP between the two treatment trials. ACE decreased and PRA increased to a similar extent in the two trials. Serum enalaprilat concentration correlated significantly (p less than 0.001) with percentage of inhibition of ACE activity. The results suggest that the pharmacokinetics and pharmacodynamics of enalapril are unaffected by preadministration of cimetidine. Thus, cimetidine does not appear to alter hepatic esterase activity toward enalapril.

Adult↗
PubMed1988

Titanium-nickel intravascular endoprosthesis: a 2-year study in dogs.

Twelve 5-mm-internal-diameter intravascular endoprostheses of noncorrosive, shape-memory titanium-nickel (TiNi) alloy were delivered transluminally by catheter and implanted in the iliac (n = 10) and femoral (n = 2) arteries of six normal dogs for either 1 or 2 years in order to evaluate the implantation technique and long-term effects. The patency rates were as follows: at 1 month, 92% (11/12); at 1 year, 100% 11/12 widely patent; 1/12 recanalized); and at 2 years, 100% (3/4 without stenosis; 1/4 with 20% stenosis). No migration, erosion, inflammation, surface thrombus, or stenosis of the side branches was seen; an absence of untoward angiographic and histopathologic effects was detected at 1 and 2 years. The neointima was completely endothelialized, without changes in thickness over time, 229.3 +/- 127.6 microns after 1 year and 223.3 +/- 216.7 microns after 2 years (p = not significant). The neointimal layer became thicker toward its distal aspect (p less than or equal to .05). Satisfactory delivery, long-term patency, and biocompatibility (manifested as a thin, stable neointima) were observed for the TiNi intravascular endoprosthesis at 1 and 2 years.

Animals↗
PubMed1988

Biological performance of TiNi shape memory alloy vascular ring prostheses: a two year study.

A method was developed for the noninvasive insertion of a vascular ring prostheses aimed at preserving arterial patency and preventing restenosis following angioplasty. Using a specially designed 7F catheter 22 nitinol (TiNi) wire prostheses (I.D. 5 mm; 0.25 mm thickness) were torsion reduced in diameter and inserted under fluoroscopy into both carotid (n = 2) and iliac-femoral arteries (n = 20) of dogs. Aspirin (650 mg BID) and Persantin (200 mg BID) were given for only 30 days postoperatively. Angiography of all rings at 1, 6, 12 months exhibited excellent biocompatibility and long term patency 91% (20/22) as reported in Trans ASAIO 32:30, 1986. Four rings inserted in the right and left common iliac arteries and femoral artery were followed for up to 2 years and exhibited 100% patency. Angiography demonstrated that the anchorage of the prostheses was stable and the lumen was uniformly covered by a thin neointimal layer of endothelial like cells. The prostheses were patent with no evidence of thrombosis or inflammation. In view of the problem of recurrent stenosis occurring during the healing period after balloon angioplasty (PTA or PTCA), this approach may lead to a new means of clinical intervention in atherosclerosis.

Alloys↗
PubMed1987

Multiple oral doses of nicardipine, a calcium-entry blocker: effects on renal function, plasma renin activity, and aldosterone concentration in mild-to-moderate essential hypertension.

We studied the effects of nicardipine administered in a 4-week fixed oral maintenance dosage (20 or 40 mg t.i.d.) on renal function, plasma renin activity (PRA), and plasma aldosterone concentration in seven patients with mild-to-moderate essential hypertension. Glomerular filtration rate and renal blood flow were measured by means of sodium thiosulfate and para-aminohippurate, respectively. Nicardipine increased renal blood flow by 11.5% +/- 4.3% (mean +/- SE; P less than 0.05) and glomerular filtration rate by 16.3% +/- 6.4% (P less than 0.05) and decreased total renal vascular resistance by 30.0% +/- 2.7% (P less than 0.05), with a significant (P less than 0.05) reduction in systolic and diastolic blood pressure as compared with placebo values. Nicardipine increased PRA significantly (P less than 0.05), whereas plasma aldosterone concentration remained unchanged. Our results indicate that nicardipine given in a multiple oral dosage has some favorable renal effects with a concomitant hypotensive action in patients with mild-to-moderate essential hypertension. Nicardipine appears to blunt the secretion of aldosterone responding to an increased PRA possibly through its calcium-antagonizing action.

Adult↗