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Biomedical subjects

M Ojima

Publications and source records attributed to M Ojima.

At least 55 records · Page 3Linked to original sources
PubMed1993

Pharmacological profile of a highly potent and long-acting angiotensin II receptor antagonist, 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4- yl]methyl]-1H-benzimidazole-7-carboxylic acid (CV-11974), and its prodrug, (+/-)-1-(cyclohexyloxycarbonyloxy)-ethyl 2-ethoxy-1-[[2'-(1H-tetrazol-5- yl)biphenyl-4-yl]methyl]-1H-benzimidazole-7-carboxylate (TCV-116).

The angiotensin II (AII) antagonistic action of 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl-1H-benzi mid azole-7 - carboxylic acid (CV-11974) was examined in in vitro assay systems, including AII receptor binding assay using membrane fractions of bovine adrenal cortex or rabbit aorta and AII-induced contraction assay using rabbit aortic strips, and CV-11974 and its prodrug, (+/-)1-(cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H- benzimidazole-7-carboxylate (TCV-116), were examined in an in vivo system of AII-induced pressor response in conscious rats. DuP 753 or EXP3174 (the main active metabolite of DuP 753) was used as the reference compound. CV-11974 inhibited the binding of [125I] AII to the bovine adrenal cortical membrane and rabbit aortic membrane with IC50 values of 1.12 x 10(-7) and 2.86 x 10(-8) M, respectively. Similar results were obtained with EXP3174. CV-11974 interacted with AII in these membrane fractions with subtype 1 receptor in a competitive manner. CV-11974 at 10(-5) M did not affect the binding of [125I]AII to subtype 2 (AT2) receptor in bovine cerebellum. CV-11974 selectively inhibited the AII-induced contraction of rabbit aortic strips in a noncompetitive manner (pD' 2, 9.97); it had no effects on the contraction induced by norepinephrine, KCl, serotonin, prostaglandin F2 alpha or endothelin. EXP3174 showed a pD'2 value of 8.95 for the AII-induced contraction. CV-11974 given intravenously and TCV-116 given orally inhibited the AII-induced pressor response in rats with ID50 values of 0.033 mg/kg and 0.069 mg/kg, respectively. These effects of CV-11974 and TCV-116 were 12 and 48 times more potent than those of EXP3174 and DuP 753, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex↗
PubMed1992

Hypothesis for the receptors of human blood platelet aggregation and its inhibition by structure-activity relationship.

We tried to clarify the size and the common charge distribution of the inhibition or stimulation of human platelet aggregation by structure-activity relationship. Numerous inhibiting and stimulating agents were able to enter the receptors. Inhibitory receptor had recess of 14 x 12.5 A in diameter. Stimulatory receptor had recess of 11 x 12 A in diameter. In the recess, there were three charges, two negative and one positive in the inhibitory receptor, and one negative and two positive in the stimulatory receptor, respectively. Charge distributions and conformation of inhibiting or stimulating agents were similar for the inhibitory agents, prostaglandin I2 (PGI2), PGD2, PGE1 adenosine and isoproterenol and conformation of the stimulating agents, thromboxane A2 (TXA2), platelet activating factor (PAF), adenosine diphosphate (ADP) and adrenaline. Each molecule had 3-10 inhibiting and stimulating conformations. The ratio of the number of conformations for inhibition and stimulating of platelet aggregation was highest for PGI2 which showed the strongest inhibitory activity. TXA2 was opposite in both respects.

Humans↗
PubMed1991

Comparison of changes in vascular resistance between choroid and other organs following ligation of carotid artery.

The changes in the choroidal vascular resistance after carotid artery ligation were compared with those in the cerebrum and the inferior rectus muscle by evaluating the changes in the blood flow by the hydrogen clearance method. Ligation of the carotid artery produced little change in the ipsilateral cerebral blood flow, but decreased the choroidal blood flow by 16-24% and the blood flow of the inferior rectus muscle by 34-40%. Although the reduction in the arterial pressure in these organs was the same, the responses of the blood flows to the changes in the arterial pressure were different. This suggests that autoregulatory capability varies from organ to organ. It is important to study the pathogenesis of carotid artery occlusion giving special consideration to these differences among the autoregulatory capabilities of various organs.

Animals↗
PubMed1990

[The inhibitory effects of glycyrrhizin and glycyrrhetinic acid on the metabolism of cortisol and prednisolone--in vivo and in vitro studies].

This experiment was carried out to investigate the inhibitory effects of glycyrrhizin and its aglycon, glycyrrhetinic acid, on the metabolism of cortisol and prednisolone in vivo and in vitro. The effects of glycyrrhetinic acid on the metabolism of cortisol were examined in vitro using rat and bovine liver homogenate. Glycyrrhetinic acid inhibits both hepatic delta 4-5-reductase and 11 beta-hydroxysteroid dehydrogenase in a dose-dependent manner, resulting in the decrease of conversion of cortisol to cortisone, dihydrocortisol and tetrahydrocortisol in rats. The concentrations of glycyrrhetinic acid inducing 50% inhibition of rat liver delta 4-5-reductase and 11 beta-hydroxysteroid dehydrogenase were 2.5 x 10(-6) M and 8.5 x 10(-6) M, respectively. Glycyrrhetinic acid also inhibits bovine liver 11 beta-hydroxysteroid dehydrogenase and 20-hydroxysteroid dehydrogenase in a dose-dependent manner, resulting in the decrease of conversion of cortisol to dihydrocortisol and prednisolone to 20-dihydroprednisolone. The concentrations of this drug inducing 50% inhibition of 11 beta-hydroxysteroid dehydrogenase and 20-hydroxysteroid dehydrogenase were 8.2 x 10(-6) M and 6.5 x 10(-6) M, respectively. This is the first report which demonstrates the marked inhibitory effects of glycyrrhetinic acid on 11 beta-hydroxysteroid dehydrogenase and 20-hydroxysteroid dehydrogenase in vitro. The effects of glycyrrhizin on the rate of metabolism of cortisol as well as prednisolone were studied in 23 patients with or without adrenal insufficiency. Glycyrrhizin had no effect on diurnal rhythm of plasma cortisol in 7 control subjects with normal pituitary adrenal axis, whereas glycyrrhizin significantly increased the half-time (T 1/2) and area under the curve (AUC) for plasma cortisol in 4 patients with adrenocortical insufficiency taking oral cortisol. Glycyrrhizin also increased T 1/2 and AUC for plasma prednisolone in 12 patients taking an oral prednisolone for at least 3 months. These results indicate that the suppression of hepatic delta 4-5-reductase, 11 beta-hydroxysteroid dehydrogenase and 20-hydroxysteroid dehydrogenase by glycyrrhizin and glycyrrhetinic acid may delay the clearance of cortisol and prednisolone and prolong the biological half-life of cortisol or prednisolone.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1988

[Effects of o,p'-DDD on pituitary-gonadal function in patients with Cushing's disease].

O,p'-DDD has a cytotoxic action and inhibits the cholesterol side chain cleavage enzyme, 11 beta-hydroxylase, 3 beta-hydroxysteroid dehydrogenase coupled with delta 5 to 4 isomerase and 21-hydroxylase of the adrenal cells. However, the effects of o,p'-DDD on gonadal steroidogenesis are still unknown. In the present study, the effects of o,p'-DDD on Plasma cortisol, pregnenolone, 17 alpha-hydroxypregnenolone (17-OH-pregnenolone), progesterone, 17 alpha-hydroxyprogesterone (17-OH-progesterone), 11-deoxycorticosterone (DOC), corticosterone, dehydroepiandrosterone (DHEA), delta 4-androstenedione (androstenedione), estradiol, and LH and FSH were investigated in 3 patients with Cushing's disease before and after the administration of o,p'-DDD. The results are presented here. In Case 1 (18 yr old female) who had had secondary amenorrhea for 2 years, the plasma levels of cortisol, pregnenolone, 17-OH-pregnenolone, DHEA, androstenedione, testosterone, estradiol and corticosterone were elevated. The basal levels of plasma LH and FSH and the responses of both gonadotropins were lower than those of women with eumenorrhea. The plasma levels of progesterone, DHEA and testosterone decreased to normal 2 months after the beginning of the administration of o,p'-DDD. She restored menstrual cycles ranging from 40 to 50 days 3 months after the administration of o,p'-DDD, but with anovulatory bleeding. She showed a biphasic body temperature pattern with plasma progesterone and estradiol levels indicating corpus luteum formation 11 months after the start of the treatment, when plasma cortisol as well as progesterone and androgen were reduced to normal. The basal levels of FSH and LH and responses of these gonadotropins were slightly improved at that time. The plasma levels of cortisol, DHEA and androstenedione were high in Case 2 (38 yr old male) and Case 3 (45 yr old male), whereas plasma testosterone level was normal in Case 2 and low in Case 3. The plasma levels of these 3 steroids were normalized 28 days after the beginning of the o,p'-DDD administration. These results suggest that o,p'-DDD does not interfere with gonadal steroidogenesis in Cushing's disease.

Adolescent↗
PubMed1988

Primary aldosteronism in childhood due to primary adrenal hyperplasia.

We present an unusual case of primary aldosteronism in childhood. A 9-year-old boy had hypertension, hypokalemia, hyporeninemia and hyperaldosteronism. Dexamethasone administration decreased plasma aldosterone transiently but failed to correct the hyperaldosteronism, excluding dexamethasone-suppressible hyperaldosteronism. Plasma aldosterone decreased with upright posture and showed a circadian rhythm. Spironolactone treatment normalized blood pressure and serum potassium and lowered aldosterone secretion. During the studies, plasma aldosterone correlated with serum cortisol but not with plasma renin. Preoperative results indicated that this patient presented the functional features of aldosteronoma. Adrenal computed tomography, scintigraphy and left venography were not diagnostic of adrenal lesions. The left adrenal venous sampling showed hypersecretion of aldosterone from the left adrenal gland. The left adrenalectomy revealed micronodular hyperplasia but resulted in a prompt and sustained reversal of hypertension and hyperaldosteronism. These findings suggest that primary aldosteronism in this patient resulted from primary adrenal hyperplasia. Thus, adrenal hyperplasia is a heterogenous group of disorders and carefully selected studies allow prospective selection of appropriate treatment.

Adrenal Hyperplasia, Congenital↗
PubMed1988

11 beta-Hydroxylase in mitochondrial fractions of functioning and non-functioning adrenocortical tumors.

The activity of 11 beta-hydroxylase was investigated in the mitochondrial fractions of 19 surgically resected adrenocortical tumors associated with Cushing's syndrome (4 adenomas and 2 carcinomas), primary aldosteronism (8 adenomas), adrenogenital syndrome (AGS) (2 carcinomas) and no hormonal symptoms (3 adenomas). Five adrenal cortices from patients with mammary carcinoma, renal cell carcinoma and pheochromocytoma were used for the normal control. The activities of 11 beta-hydroxylation of deoxycorticosterone and of 11-deoxycortisol in the control adrenal cortices were 0.66-2.16 pmole/mg protein/min (mean: 1.28 pmole/mg protein/min) and 0.25-0.77 pmole/mg protein/min (mean: 0.56 pmole/mg protein/min), respectively. The activities in adenomas and carcinomas associated with Cushing's syndrome were in the range of normal control. The activities in aldosteronomas were significantly higher in 4 cases than those of the normal control and in the range of the normal control in 4 cases, suggesting that the higher activity of 11 beta-hydroxylase is one of the important factors causing mineralocorticoid excess. The activities in adrenocortical carcinomas with AGS were significantly lower, corroborating clinical findings of androgen excess with suppressed production of mineralocorticoid or glucocorticoid. The activities in two cases of nonfunctioning adenomas were in the range of the normal control, but the third case showed higher activity than the normal control. These results show that the abnormal activity of mitochondrial 11 beta-hydroxylase exists in some aldosteronomas, non-functioning adrenocortical adenomas and carcinomas with AGS.

Adenoma↗
PubMed1988

Changes in choroidal blood flow following ligation of common carotid artery.

The effects of carotid artery ligation on choroidal blood flow were studied in 30 rabbits using a hydrogen clearance method. The choroidal blood flow (ChBF) decreased significantly to about 75% for 60 minutes after the ipsilateral ligation of the common carotid artery. In 11 of the rabbits ChBF was measured both one and six weeks after ligation. ChBF recovered to 88% of the resting level one week after the ligation, and returned to the resting values six weeks after the ligation. The left carotid artery was ligated six weeks after ligation of the right carotid artery, and there was not any significant change in the ChBF of the right eye. It seemed that the recovery of the ChBF of the right eye was not through the contralateral carotid artery.

Animals↗
PubMed1987

Congenital 17 alpha-hydroxylase deficiency: a clinicopathologic study.

The histopathologic features of the adrenal glands in three cases of congenital 17 alpha-hydroxylase deficiency are described in relation to clinical and endocrine findings. Diffuse or nodular adrenocortical hyperplasia, particularly in the zonae fasciculata and reticularis, was observed in all cases examined. The hyperplastic adrenal cortices were composed of cells with morphologic features of hypercorticism and hyperstimulation. Myelolipomatous lesions were detected in two cases. These morphologic findings were consistent with excessive adrenocorticotropic hormone secretion in this disorder. In all the cases examined, the plasma aldosterone concentration was within normal limits, and plasma renin activity was suppressed prior to dexamethasone treatment. Morphologically, however, hyperplasia of the cells with abundant mitochondria and smooth endoplasmic reticulum seemed to involve the zona glomerulosa. Nonencapsulated nests of hypertrophied cortical cells in periadrenal tissue were remarkable in one case. From these morphologic findings, we postulated hyperfunction of the zona glomerulosa as well as involvement of corticosteroids from the zona glomerulosa in the pathophysiology of this disorder.

Adrenal Cortex Hormones↗
PubMed1987

Multiple forms of immunoreactive renin in human adrenocortical tumour tissue from patients with primary aldosteronism.

There is increasing evidence which suggests that the adrenal gland contains the renin-angiotensin cycle. The localization of renin has been reported to be mainly in the zona glomerulosa rather than the fasciculata medullary portion. In the present study we have investigated extracts from aldosteronomas (n = 3), which are believed to derive from the zona glomerulosa cells. In addition, we have attempted to characterize the biochemical properties of the adrenal renin. Sizable quantities of renin-like activity (32.0 +/- 7.7 ng of angiotensin I generated h-1 mg-1 of protein, mean +/- SEM) were detected in the extracts. This renin-like activity was inhibited by anti-renin antibody raised against pure renin (mean, 95% of the total renin-like activity), indicating that it was not due to the non-specific action of proteases such as cathepsin D. The optimum pH of the tissue renin-like enzyme was 6.0 for rat plasma substrate. Differences were found, however, in the molecular mass (36,000, 37,000, 44,000 and 48,000), binding to concanavalin A and isoelectric points (4.40, 4.68 and 5.00). These results confirm the existence of specific renin in aldosteronoma. Renin microheterogeneity could be evidence for local production of the enzyme.

Adrenal Cortex Neoplasms↗
PubMed1987

An adrenocortical tumor secreting weak mineralocorticoids.

An adrenocortical carcinoma (15.5 g) secreting excessive amounts of steroids with weak mineralocorticoid activity in a 25-year-old woman was studied with particular reference to its in vivo and in vitro secretions of steroids. Severe hypertension, occasional low serum potassium and suppressed PRA were the major clinical findings, and were improved with removal of the tumor. In the preoperative stage, plasma levels of 11-deoxycorticosterone, 18-hydroxy-11-deoxycorticosterone, corticosterone and 18-hydroxycorticosterone were all increased. However, the plasma level of aldosterone was repeatedly normal. Although plasma levels of pregnenolone, 17-hydroxypregnenolone, progesterone and 17-hydroxyprogesterone were very high, those of other late step steroids, i.e. 11-deoxycortisol, cortisol, dehydroepiandrosterone, androstenedione and testosterone were almost normal. From these findings, a major etiological role of weak mineralocorticoids such as 11-deoxycorticosterone, 18-hydroxycorticosterone and corticosterone in her hypertension was suggested. Pregnenolone and 17-hydroxypregnenolone in tumor tissue were increased, but 11-deoxycorticosterone, corticosterone, aldosterone, cortisol and adrenal androgens such as dehydroepiandrosterone, androstenedione and testosterone were below normal or low normal. In vitro production of 11-deoxycorticosterone, aldosterone or cortisol by the tumor tissue slices was very low and scarcely responded to synthetic ACTH.

17-alpha-Hydroxypregnenolone↗
PubMed1987

A hitherto unreported case of 21-hydroxylase deficiency associated with Bartter's syndrome and a balanced 6-9 translocation.

A description is given of a girl with the non-salt-losing type of congenital adrenal hyperplasia (CAH) and with Bartter's syndrome. In addition, the patient had a balanced translocation between 6q and 9p. Although the possibility cannot be ruled out fully that an excess of progesterone might modify the renin-aldosterone axis to some extent, the finding that dexamethasone therapy improved the clinical features of CAH but failed to correct metabolic disorders in electrolyte balance strongly suggests the coexistence of the two clinical entities. Chloride transport at the distal tubule was impaired moderately in the patient, which suggests that her defective reabsorption of chloride was responsible for the impaired renal handling of sodium that is often observed in patients with Bartter's syndrome. It appears that the reciprocal translocation is unrelated to both CAH and Bartter's syndrome since the same translocation was found in her healthy mother and siblings.

Adolescent↗
PubMed1986

Biochemical evidence for existence of immunoreactive renin in human prolactinoma tissue.

High activity of renin was demonstrated in human prolactinoma tissue. This activity was almost completely inhibited by specific antibody raised against human renal renin, indicating that it was not due to the nonspecific action of proteases. The specific activity of renin was 5.04 ng of angiotensin I generated/mg of protein per h, comparable to that of the pituitary tissue prepared from postmortem human subjects. The biochemical properties of the prolactinoma renin were generally similar to those of well-known kidney enzyme, such as molecular mass (Mr = 46,000), optimum pH (6.0), and glycoprotein nature. However, the isoelectric points (pI) of the prolactinoma renin (pI = 4.90, 5.04, 5.24 and 5.41) differed somewhat from those of plasma and kidney renins reported hitherto. These results indicate that true renin can be produced in human prolactinoma tissue.

Chromatography, Affinity↗
PubMed1986

[A case of 21-hydroxylase deficiency and Bartter's syndrome associated with a balanced 6-9 translocation].

A 17-year-old female weighing 37 kg and 140 cm in height was referred to our hospital for evaluation of dwarfism and primary amenorrhea. She was delivered with 3350 g in weight and 50 cm in height after a ten month pregnancy without complications. No abnormal findings were revealed in physical appearance except critomegaly. Episodes of nausea, vomiting and dehydration were rare throughout her childhood, but she had a tendency to salt craving. At the age of 14, her height was 140 cm. On admission, her physical development was markedly retarded for her age, except external genitalia. Diffuse pigmentations on the trunk and extremities were observed. Her blood pressure was normal (112/62 mm Hg). Serum potassium concentration was 2.9 mEq/L. Arterial-blood gas analysis revealed metabolic alkalosis. Both of renin activity (PRA) and aldosterone concentration (PAC) in plasma at rest were markedly elevated to 15.5 ng/ml/h and 107.1 ng/dl, respectively. The plasma concentrations of pregnenolone (1449 ng/dl), progesterone (178 ng/dl), 17-OH-pregnenolone (1613 ng/dl), 17-OH-progesterone (180 ng/dl), dehydroepiandrosterone (3706 ng/dl), androstendione (824.6 ng/dl) and testosterone (900 ng/dl) were high, whereas deoxycorticosterone (15.7 ng/dl), corticosterone (0.65 microgram/dl) and cortisol (6.8 micrograms/dl) were within normal limits. Urinary 17-KS excretion showed high levels between 65.7 and 109.4 mg/day, while urinary 17-OHCS excretion was normal (5.7-7.0 mg/day). Vascular response to angiotensin II (A-II) was attenuated. Distal fractional chloride reabsorption was decreased (CH2O/CH2O+CCl = 0.62, normal: 0.92 +/- 0.04). Moderate hyperplasia of the juxtaglomerular cells was demonstrated in biopsy specimen of the kidney. Cytogenetic studies showed a 46, XX chromosome constitution with translocation of the long arm of chromosome 6 to the short arm of chromosome 9. Her mother as well as younger brother and sister, whose electrolytes and arterial-blood gas analysis showed normal values, had chromosomes with the same translocation. Treatment with dexamethasone (2 mg/day) reduced every adrenal steroids to normal range, but PRA and PAC remained high levels. Furthermore, neither hypokalemic alkalosis nor vasoreactivity to exogenous A-II was improved. Indomethacin (75 mg/day) decreased urinary excretion of prostaglandin E2 from a high level of 738.4 ng/day to 433.4 ng/day and normalized metabolic alkalosis. Vascular response to A-II was moderately improved. However, serum potassium remained low.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗