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Biomedical subjects

A Fujimura

Publications and source records attributed to A Fujimura.

At least 145 records · Page 8Linked to original sources

Comparison of venodilatory effect of amrinone and theophylline in human subjects.

Amrinone, a positive inotropic agent, is a selective phosphodiesterase III inhibitor and exerts vasodilatory effect on venous vessels. The present study was undertaken to compare the venodilatory effect of amrinone and theophylline, a nonselective phosphodiesterase inhibitor, in eight healthy male subjects. In a randomized crossover design, one of these drugs was infused into the dorsal hand vein preconstricted by phenylephrine and its diameter was measured using a linear variable differential transformer. The value of maximum vasodilation for amrinone (mean +/- standard deviation, 106% +/- 17%) was similar to that for theophylline (mean +/- standard deviation, 108% +/- 14%). However, the infusion rate of amrinone needed to induce 50% of maximum vasodilation was significantly less than that of theophylline (25 +/- 15 micrograms/minute vs. 192 +/- 87 micrograms/minute, respectively; P < 0.01). These findings suggest that the venodilatory activity of amrinone is more potent than that of theophylline in human subjects.

Adrenergic alpha-Agonists↗

Effect of losartan, an angiotensin II receptor antagonist, on response of cortisol and aldosterone to adrenocorticotrophic hormone.

Many imidazole derivatives are shown to inhibit adrenal steroid biosynthesis. The present study was undertaken to examine an effect of another imidazole derivative, losartan (an angiotensin II receptor antagonist), on responses of cortisol and aldosterone to adrenocorticotrophic hormone (ACTH). Nine patients with essential hypertension were given placebo orally for 7 days and 50 mg of losartan for the next 9 days. Response of serum cortisol and plasma aldosterone to intramuscular ACTH injection were determined before and at the end of the treatment with losartan. Serum cortisol and plasma aldosterone significantly increased after ACTH injection in both periods of treatment (placebo and losartan). The increments in these parameters during treatment with losartan were not significantly different from those during treatment with placebo. These results suggest that the inhibitory effect of losartan on adrenal steroid biosynthesis is negligible.

Adrenocorticotropic Hormone↗

Chronopharmacology of enalapril in hypertensive patients.

The pharmacokinetics and pharmacodynamics of enalapril, an angiotensin converting enzyme inhibitor, are reported to vary with the time of administration. The present study was undertaken to examine whether the effect of enalapril on plasma bradykinin (BK), substance P and prostaglandin E2 (PGE2), which are likely to be involved in the mechanism of enalapril-induced cough, might also be affected by its time of administration. Enalapril 5 mg or placebo was given orally at 10:00 h (day trial) or 22:00 h (night trial) to 12 patients with essential hypertension. Serum concentrations of total drug (enalapril + enalaprilat, its active metabolite) during the day and night trials did not differ significantly at any time. However, serum enalaprilat tended to be higher and its maximum concentration greater in the day trial than in the night trial. Blood pressure 24 h after administration of enalapril was reduced at 22:00 h, but not at 10:00 h. Plasma BK tended to increase following enalapril administration at 10:00 h, but not at 22:00 h. Remarkable increases in plasma BK were observed in two patients in the day trial and one of them also complained of cough. However, no such increase in plasma BK or subsequent adverse effect were recorded in the night trial. Plasma substance P and PGE2 did not change significantly following enalapril administration either in the day or night trial. The results suggest that the response of BK to enalapril is affected by the time of administration. In patients who complain of cough during treatment with enalapril during the daytime, this adverse effect might be diminished or eliminated by a switch to night-time administration.

Adult↗

Studies on the development of the articular part of the temporal bone with special reference to the postglenoid process.

The development and significance of the postglenoid process on the articular surface of the temporal bone were studied using 217 Indian skulls, which were divided by their level of tooth eruption into 6 developmental stages; preeruption period (Stage I), initial stage (m1 eruption) of the deciduous dentition period (Stage II), middle stage (m2 eruption) of the deciduous dentition period (Stage III), late state (eruption of 20 deciduous teeth) of the deciduous dentition period (Stage IV), mixed dentition period (Stage V), and permanent dentition period (Stage VI). Each skull was mounted on a Kraniophor in such a way that the auriculoorbital (Frankfurt) plane was positioned vertical to the horizontal plane and photographed at a focal distance of 40 cm. Using the Frankfurt plane as a base line, the vertical distances to the lowest point of the postglenoid process (a-A), to the deepest point of the mandibular fossa (b-B), and to the mid-point of the articular tubercle (c-C) were measured. The distances from various points of the mandibular fossa to the articular surface of the temporal bone were measured at the level of the Frankfurt plane. The results may be summarized as follows: The length of the postglenoid process as measured from the Frankfurt plane was 0.58 mm at Stage I and 0.75 mm at Stage II. It increased by 0.6-1.0 mm at each developmental stage. By Stage VI, it had increased to 3.85 mm (six- to seven-fold increase from the initial value). The anteroposterior width of the postglenoid process remained almost unchanged throughout the developmental stages. The growth of the articular structures of the temporal bone from the preeruption to deciduous dentition period increased 73% in the total anteroposterior dimension (5.22 mm) and 44% in the total vertical dimension (3.32 mm). The vertical dimension of the mandibular fossa began to rapidly increase following the eruption of the deciduous first molars.

Adolescent↗

Influence of aging on the oxidative and conjugative metabolism of propranolol.

The influence of aging on the hepatic metabolism of propranolol, i.e. conjugation, side-chain oxidation and ring oxidation, was investigated in 32 in-patients aged 30 to 84 yrs. Plasma propranolol concentration and main urinary metabolites [propranolol glucuronide (PPLG), naphthoxylactic acid (NLA), and 4-hydroxypropranolol (40HP)] were determined after a single oral dose of 20 mg propranolol. There were significant correlations between age and 1) maximum propranolol concentration, 2) area under the plasma concentration-time curve, and 3) elimination half-life. The apparent oral clearance of propranolol was inversely correlated with age. Partial metabolic clearance (PMC) to 40HP (ring oxidation) and PMC to NLA (side-chain oxidation) were significantly correlated with age, while PMC to PPLG was not. These observations suggest that there are age-related reductions in two oxidizing capacities, while there is no significant influence of aging on the conjugating capacity. The age-related reduction in oral clearance of propranolol may be mainly caused by the decline in the capacity of two different oxidation pathways.

Adrenergic beta-Antagonists↗

Comparison of the pharmacokinetics, pharmacodynamics, and safety of oral (Catapres) and transdermal (M-5041T) clonidine in healthy subjects.

The pharmacokinetic as well as pharmacodynamic properties of a transdermal clonidine, M-5041T (M) and its safety were compared with those of oral clonidine, Catapres (Nippon Boehringer Ingelheim, Hyogo, Japan). One patch of M containing 6 mg of clonidine was applied on the right chest for 3 days or one tablet of Catapres (.075 mg) was given orally every 12 hours for 3 days in eight healthy subjects. The study was conducted by a crossover design with 14 to 16 days' interval between the cross-over. Blood and urine samples for clonidine concentration were obtained, and blood pressure (BP) was measured for a 168-hour period after application of M and for a 96-hour period after initiation of Catapres therapy. Plasma concentration of clonidine increased gradually after application of M and decreased gradually after removal, whereas this parameter increased rapidly during the absorption phase and decreased rapidly in the elimination phase after each dosage of Catapres. Elimination half-life of clonidine after removal of M was significantly greater than that after the final dosage of Catapres. No significant difference was observed in maximum plasma concentration or area under the plasma concentration-time curve between the two trials. The BP lowering effects of M and Catapres did not differ significantly. Adverse symptoms occurred more frequently during Catapres therapy than during treatment with M. Most of these symptoms were observed when plasma clonidine concentration was relatively higher in each trial. These results suggest that M is effective for the treatment of hypertension with a lower incidence of adverse symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗

Renal clearance of lomefloxacin is decreased by furosemide.

The interaction between lomefloxacin, a new quinolone, and furosemide, a loop diuretic, has been examined. Oral lomefloxacin 200 mg and furosemide 40 mg were given together or separately to 8 healthy subjects, and blood and urine samples were obtained over the following 12 h. The plasma concentrations of lomefloxacin following coadministration with furosemide were higher than after lomefloxacin alone and its AUC was increased, and its total and renal clearances were decreased. No change in the pharmacokinetics of furosemide was found after coadministration of lomefloxacin. As quinolones and furosemide are reported to be excreted in urine by the renal tubular anion transport system, the present results suggest that the renal tubular secretion of lomefloxacin is diminished by furosemide. It is not clear whether this pharmacokinetic interaction might be clinically important.

Adult↗

Time-dependent change in the toxic effects of amikacin on renal functions.

The present study was undertaken to examine whether there was a time-dependent change in the toxic effects of amikacin, an aminoglycoside, on renal functions. Male Wistar rats were maintained under conditions of light from 7 am to 7 pm and dark from 7 pm to 7 am. Amikacin (1.2 g/kg) was injected intraperitoneally to animals at 4 am, 10 am, 4 pm or 10 pm. Glomerular function estimated by creatinine clearance (Clcr) and tubular function estimated by urinary excretion of a loop diuretic, furosemide, which was excreted in urine mainly by tubular secretion, were determined before and 24 hours after amikacin injection. The values of these parameters were reduced by amikacin at each observation point. The magnitude of these decrements was greatest at 4 pm both for Clcr and urinary furosemide excretion. These results suggest that the toxic effects of amikacin on renal glomerular and tubular functions vary with its time of administration.

Amikacin↗

Daily variation in the urinary excretion of furosemide in young and aged rats.

We have recently demonstrated that the time-dependent difference in urinary excretion of furosemide, a loop diuretic, diminishes during the aging process and disappears by 18 months of age in rats. The present study was undertaken to examine whether the amplitude of the daily variations in the urinary excretion of furosemide or their pattern, or both, are influenced in aged animals. Young (3 months of age) and aged (30 months of age) Wistar rats were maintained under conditions of light from 7 am to 7 pm and dark from 7 pm to 7 am. Furosemide (30 mg/kg) was given orally at 4 am, 8 am, 12 am, 4 pm, 8 pm or 12 pm. Urine was collected for 8 hours after furosemide administration and urinary excretion of furosemide was determined. There were significant daily variations in the urinary furosemide and the urine volume with the peak at 8 am and the trough at 12 pm in both groups of rats. The differences in these parameters between the 8 am and 12 pm trials were significantly smaller in the aged than in the young rats. These results suggest that the age-related alteration in the time-dependent phenomenon of furosemide is caused by the decreased amplitude of the daily variation in the urinary furosemide excretion and its diuretic effect.

Age Factors↗

Effect of angiotensin II type 1 receptor antagonist on urinary prostaglandin E2 excretion following furosemide in rats.

The present study was undertaken to examine an effect of an angiotensin II type 1 (AT1) receptor antagonist on urinary prostaglandin E2 (PGE2) excretion following furosemide, a loop diuretic, in rats. Furosemide (30 mg/kg) was given orally with or without pretreatment with derapril (30 mg/kg), an angiotensin converting enzyme inhibitor, TCV-116 (1 mg/kg), an AT1 receptor antagonist, or losartan (10 mg/kg), another AT1 receptor antagonist. The 6-hour urine was collected following furosemide, and the urinary excretion of PGE2 was determined. The urinary PGE2 increased significantly following furosemide alone. However, such a furosemide-induced increase was not observed with pretreatment with derapril, TCV-116 or losartan. These results suggest that the increased urinary excretion of PGE2 following furosemide is blunted by derapril, TCV-116 and losartan. As TCV-116 and losartan are selective AT1 receptor antagonists, the effect of furosemide on renal PGE2 production, as reflected by the urinary PGE2, might be mediated by an activation of AT1 receptors.

Angiotensin II↗

Administration time-dependent change in the effect of spironolactone in aged rats.

We have previously demonstrated that the natriuretic effect of spironolactone, a competitive antagonist of mineralocorticoid, varies with its administration time in young rats. The present study was undertaken to examine the influence of aging on chronopharmacological profiles of the agent. Spironolactone (10 and 50 mg/kg) was given orally at 12 am or 12 pm in young (12 weeks old) and aged (28 months old) Wistar rats. The 8-hour urine was collected after each administration, and the urinary sodium excretion was determined. The urinary sodium excretion increased dose-dependently following spironolactone in the young and aged groups of rats. The increments in this parameter in the 12 pm trial were significantly greater than those of the 12 am trial in the young rats. However, such an administration time-dependent difference in the effect of spironolactone was diminished and did not reach statistical significance in the aged animals. These results suggest that the mode of the administration time-dependent change in the effect of spironolactone is altered with age.

Aging↗

Administration time-dependent toxicity of a new immunosuppressive agent, tacrolimus (FK 506).

We have previously shown that blood concentrations of tacrolimus, a new immunosuppressive agent, were greater when it was administered orally at 10 pm than when it was administered at 10 am in rats. The present study was undertaken to examine whether the toxic effects of tacrolimus show administration time-dependent variations. Male Wistar rats were maintained under conditions of light from 7 am to 7 pm and dark from 7 pm to 7 am. Tacrolimus (1 and 4 mg/kg) was given orally at 10 am (day trial) or 10 pm (night trial) for 14 days. Blood samples were obtained at 24 hours after the final dosage of the agent. Weight gain was smaller in the night trial than in the day trial. Plasma concentrations of urea and creatinine increased significantly in the night trial while the elevations in these parameters were not observed in the day trial. These results suggest that the toxic effects of tacrolimus also vary with its time of oral dosage.

Animals↗

Administration time-dependent change in the effect of spironolactone in rats.

The present study was undertaken to examine whether the natriuretic effect of spironolactone, a competitive antagonist of mineralocorticoid, varies with its time of administration. Wistar rat maintained under the condition of light from 7 hr to 19 hr were divided into two groups. The first group had a bilateral adrenalectomy and received a 50-mg deoxycorticosterone acetate (DOCA) tablet intraperitoneally (DOCA group). The second group had a sham operation (control group). Spironolactone (50 mg/kg) was given orally at 12 hr or 24 hr, and the 8-hr urine was collected. At the end of the experiment, the blood sample for measurement of aldosterone was obtained at 12 hr and 24 hr in the control group. The natriuretic effect of spironolactone in the 24 hr-trial was significantly greater than that of the 12 hr-trial in the control group. However, such a time-dependent difference was diminished and did not reach statistical significance in the DOCA group. The plasma aldosterone concentration at 24 hr was significantly higher than that at 12 hr in the control group. These results suggest that the natriuretic effect of spironolactone varies with its time of administration. Daily variation in mineralocorticoid activity might be involved in this chronopharmacological phenomenon of spironolactone.

Administration, Oral↗

Decrease in the time-dependent difference in urinary excretion of furosemide with age.

The influence of age on the time-dependent difference in urinary excretion of furosemide, a loop diuretic agent, was examined in this longitudinal study. Male Wistar rats were maintained under conditions of light from 07:00 to 19:00 h and dark from 19:00 to 07:00 h. Furosemide (30 mg/kg) was given orally at 12:00 h (day trial) or 00:00 h (night trial) to rats at 3 months of age, and urine was collected for 8 h after dosage. Thereafter, the identical protocol was repeated using the same animals at 6, 9, 12, 15, 18, and 21 months of age. The urinary excretion of furosemide was significantly greater in the day than in the night trial at 3 months of age. Such a time-dependent difference was observed for up to 15 months, but disappeared at 18 and 21 months of age. The time-dependent difference in urinary excretion of furosemide (day trial - night trial) decreased gradually throughout the observation period of the study. These results suggest that the time-dependent difference in the urinary excretion of furosemide diminishes during the aging process and disappears by 18 months of age in male Wistar rats.

Administration, Oral↗

Influence of application site of a new transdermal clonidine, M-5041T, on its pharmacokinetics and pharmacodynamics in healthy subjects.

Influence of application site of a new transdermal clonidine, M-5041T(M), on its pharmacokinetics and pharmacodynamics were evaluated in eight human subjects. One patch of M-6 mg was applied for 3 days on the right chest (first trial), on the left arm (second trial), and on the upper abdomen (third trial). Blood samples for clonidine concentration were taken, and blood pressure (BP) was measured for a 120-hour postapplication period. Plasma concentrations of clonidine increased after application of M in each trial. This parameter in the second trial was significantly greater than that of the first and third trials. The values of maximum plasma concentration and area under the plasma concentration-time curve in the second trial were greater than those of other trials, but the differences did not reach significance. The BP-lowering effect of M in the second trial was significantly greater than that of the third trial. These results suggest that the plasma concentrations of clonidine after application of M and its hypotensive effect are affected by the site of application in human subjects.

Abdomen↗

Pharmacokinetics and pharmacodynamics of a new transdermal clonidine, M-5041T, in healthy subjects.

The pharmacokinetic as well as the pharmacodynamic properties of a new transdermal clonidine, M-5041T (M), and its safety were evaluated after single and repeated applications. In the single-application study, one patch of M (4 mg-->6 mg-->8 mg) was applied for 3 days in eight healthy subjects. In the repeated-application study, first (0-72 hours), second (72-144 hours), and third (144-216 hours) patches of M 6 mg were applied in seven healthy subjects. In the single-application study, plasma clonidine concentration increased in a dose-dependent manner after application of M. Maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) increased in a dose-dependent manner, but the difference did not reach significance. Time to maximum concentration, elimination half-life, and total and renal clearance did not differ significantly among three trials. Blood pressure (BP) decreased gradually after application of each dose of M. The BP-lowering effect of M 8 mg was greater than that of M 4 mg and 6 mg. Adverse effects such as erythema and drowsiness were reported in some subjects. No subject had to be withdrawn from the study because of the appearance of adverse effects. In the repeated-application study, plasma concentration of clonidine increased up to 48 hours after application of first patch, and thereafter remained within a relatively narrow range until removal of third patch. The Cmax and AUC did not differ significantly among three trials. Blood pressure during an active period decreased significantly during treatment with M, whereas BP at midnight did not change significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗