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Biomedical subjects

T Horiuchi

Publications and source records attributed to T Horiuchi.

At least 397 records · Page 22Linked to original sources
PubMed1988

Phorbol ester receptors and the induction of differentiation in the human T lymphoblastic cell line MOLT-3.

To examine the mechanism of induction of differentiation in the human malignant T-lymphoblastic cell line, MOLT-3, by 12-O-tetradecanoylphorbol-13-acetate (TPA), the role of receptors for phorbol esters was investigated. Binding of [20-3H]-phorbol-12,13-dibutyrate to TPA-resistant subclones derived from MOLT-3 was less than 50% of that of the parental MOLT-3. Scatchard analysis showed that the concentration of phorbol ester receptors in a TPA-resistant subclone was about 50% of that in the parental MOLT-3, but affinities of binding were similar, indicating that more than a certain number of phorbol ester receptors is required to induce differentiation by TPA in this human T cell line.

Caenorhabditis elegans Proteins↗
PubMed1988

Role of endogenous arginine vasopressin in potentiating corticotropin-releasing hormone-stimulated corticotropin secretion in man.

Exogenously administered vasopressin (VP) augments ACTH secretion stimulated by CRH. This study was performed to elucidate the role of endogenous VP in potentiating CRH-induced ACTH secretion in man. Synthetic human CRH (100 micrograms) was injected iv into seven normal men after they had been water loaded (20 mL/kg; 60 and 30 min before CRH injection; WL-CRH test) and water deprived (water restriction for 18 h before CRH injection; WD-CRH test). Blood samples were obtained before and 5, 15, 30, 60, 90, and 120 min after CRH injection at 0900 h for determination of plasma ACTH, cortisol, arginine vasopressin (AVP), CRH, and catecholamine levels and osmolality. Urine was obtained immediately before and 120 min after CRH injection for determination of osmolality. The mean plasma AVP levels were significantly higher during the WD-CRH test [1.8 +/- 0.4 (+/- SE) to 1.9 +/- 0.4 pmol/L] than during the WL-CRH test (0.6 +/- 0.1 to 0.9 +/- 0.1 pmol/L). The mean plasma ACTH and cortisol levels rose significantly from basal (4.5 +/- 0.6 pmol/L and 320 +/- 20 nmol/L, respectively) to peak values of 14.0 +/- 2.1 pmol/L at 30 min and 700 +/- 50 nmol/L at 60 min, respectively, during the WD-CRH test. During the WL-CRH test, mean basal plasma ACTH and cortisol levels were 3.5 +/- 0.7 pmol/L and 420 +/- 50 nmol/L, respectively, and reached peak values of 7.7 +/- 1.1 pmol/L at 60 min and 550 +/- 40 nmol/L at 30 min, respectively. Both the mean peak levels and integrated ACTH and cortisol responses were significantly higher during the WD-CRH than during the WL-CRH test. There was no significant difference between the plasma CRH and catecholamine concentrations in both tests. These results suggest that endogenous AVP potentiates CRH-stimulated ACTH secretion and, thus, plays a physiologically significant role in regulating CRH-stimulated ACTH and cortisol secretion in man.

Adrenocorticotropic Hormone↗
PubMed1988

Dehydroepiandrosterone sulfate (DHEA-S) and 3', 5'-cyclic adenosine monophosphate (cAMP) production in a cultured human adrenocortical carcinoma cell line (SW-13).

Very little has been known of the biochemical function of a human adrenocortical carcinoma cell line, SW-13. In this study, the production of several adrenal steroids and 3', 5'-cyclic adenosine monophosphate (cAMP) were investigated in this cell line. The cells were incubated in L-15 medium containing 0.1% bovine serum albumin with several reagents in an atmosphere of 5% CO2 and 95% air for 2 hours at 37 degrees C. Aldosterone (Ald), corticosterone (B), cortisol (F), dehydroepiandrosterone sulfate (DHEA-S) and cAMP were simultaneously assayed by specific radioimmunoassays in the medium and cells. Significant increases in cAMP production were observed by cholera toxin (10 ng/ml) and forskolin (10 nM), both direct stimulators of adenylate cyclase, in the cAMP concentration without an increase in the steroids. The DHEA-S concentration in the medium was significantly increased by angiotensin-II (10(-7)M), noradrenalin (3 X 10(-5) M), adrenalin (3 X 10(-5) M) or alpha-melanocyte-stimulating hormone (alpha-MSH, 10(-7) M), none of which was associated with cAMP production. Neither adrenocorticotropin (10(-10) M) nor human chorionic gonadotropin (500 mIU/ml) stimulated the release of the steroids or cAMP production. A calcium ionophore, A23187 (10(-7) M), and 12-O-tetradecanoylphorbol-13-acetate (10(-8) M), a direct stimulator of protein kinase C, stimulated the release of DHEA-S, but not those of Ald, B and F. The results suggest that SW-13 retains functioning adenylate cyclase which, however, is not linked with steroidogenesis and that DHEA-S is produced probably by the mechanisms which involve protein kinase C system or calcium ion. This report provides the first demonstration of cAMP and DHEA-S production in SW-13 and suggests that this cell line is potentially useful for investigating the mechanisms of steroidogenesis in the human adrenal cortex.

Adrenal Cortex Neoplasms↗
PubMed1988

Surgical closure of ventricular septal defect in the first year of life: forty-three consecutive successful cases.

Forty-three infants (less than 12 months of age) underwent VSD closure without operative mortality between June 1982 and December 1987. Average age and body weight at the operation were 6.9 months and 5.3 kg, respectively. Associated cardiac anomalies were PDA (11 patients), ASD (5) and PS (1). Preoperative pulmonary to systemic peak pressure ratio (Pp/Ps), resistance ratio and flow ratio, and pulmonary vascular resistance were 0.79 +/- 0.15, 0.29 +/- 0.16, 2.52 +/- 0.60 and 3.05 +/- 1.94 unit.m2, respectively. VSD was closed under combined surface/perfusion hypothermia with total circulatory arrest in 25 patients and standard cardiopulmonary bypass in 18. All patients were discharged from the hospital in good condition, but there was one late death due to pneumonia. Postoperative Pp/Ps decreased to 0.39 +/- 0.11. Most of the patients demonstrated satisfactory body weight gain after VSD closure. These results support our current policy of aggressive surgical intervention for refractory VSD in the early stage of life.

Cardiac Surgical Procedures↗
PubMed1988

Development of pressure monitoring and controlling system for quantitative analysis of experimentally induced perilymph fistula.

The cause of perilymph fistula, a subgroup of sudden deafness, has not been clearly understood. To study its etiology quantitatively, the inner ear pressure monitoring system with a computer controlled pressurizing device and three types of low-pressure monitoring sensors was constructed and utilized in ex vivo experiments using white guinea pigs. Hypothesizing that cerebrospinal pressure increases cause rupture of the round window membrane, direct and indirect pressurization to cerebrospinal region and simultaneous measurement of inner ear and cerebrospinal pressures were carried out. Ruptures of the round window membranes were seen in the experiments with direct saline infusion into the cochlea when the increment of inner ear pressure exceeded 500 mmH2O. There was no sign of rupture when squeezing abdomen was employed as an indirect pressurization, although cerebrospinal pressure increased.

Animals↗
PubMed1988

Spontaneous fractures of the hip in the elderly.

The authors found 41 patients with 42 fractures of the hip who had no distinct history of trauma in the total of 1,449 hip fractures treated. They were all women ranging in age from 64 to 91 years. Most of the fractures were of intracapsular type. Three extracapsular fractures, however, were found. Fractures were randomly selected with clear history of trauma, which were matched to the patients with no trauma for age, sex, and type of fracture as a control group. The grades of osteoporosis of the femoral neck, estimated with the Singh index, and of the spine, estimated with the spinal score, were noted statistically significantly higher in the patients than those in the control group. Most of spontaneous fractures of the hip in the elderly are considered similar phenomena to the compression fractures of the dorsolumbar spine.

Aged↗
PubMed1988

Removal and recovery of cholesterol in thermofiltration.

Thermofiltration, a system of membrane plasmapheresis for LDL apheresis, was applied to the treatment of hypercholesterolemic patients to assess its lipid lowering potential, clinical feasibility and post-treatment lipid recovery. Plasma separated by a membrane separator was warmed above physiologic temperature, filtered with a plasma filter and returned to the patient on-line without requiring supplemental plasma product infusion. One calculated plasma volume was treated. Treatment schedules were weekly, biweekly or monthly. Patients treated by thermofiltration in this study were diagnosed as type II hypercholesterolemia. Reductions and sievings of high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol were evaluated. In addition, post-treatment solute recovery was assessed. The reduction ratios of HDL cholesterol and LDL cholesterol were 0.31 +/- 0.08 and 0.58 +/- 0.08, respectively (mean +/- S.D. of 7 patients). Sieving coefficients of the plasma filter for HDL cholesterol and LDL cholesterol were 0.62 +/- 0.12 and 0.03 +/- 0.02, respectively (mean +/- S.D. of 32 treatments). Cholesterol reduction fitted well to a single pool model. HDL cholesterol recovered significantly faster than LDL cholesterol and LDL cholesterol recovery differed among individuals. For some patients total cholesterol and LDL cholesterol levels were lowered by the biweekly treatment while for others the weekly treatment was required. Significant removal of LDL cholesterol with sparing of HDL cholesterol was achieved without the requirement for plasma products.

Adult↗
PubMed1987

Effect of catecholamine on aldosterone release in isolated rat glomerulosa cell suspensions.

Effect of adrenergic activity on the adrenal steroidogenesis and the modulation by catecholamines of aldosterone release were studied in isolated rat adrenal cell suspensions. Isoproterenol, norepinephrine and epinephrine, but not dopamine, caused statistically significant increase in aldosterone release. Both prazosin (alpha 1 antagonist) and yohimbine (alpha 2 antagonist) suppressed the norepinephrine-induced aldosterone release in a dose dependent manner, respectively. Both atenolol (beta 1 antagonist) and ICI 118-551 (beta 2 antagonist) also blocked (-)-isoproterenol-induced aldosterone release in a dose dependent manner, respectively. Neither (-)-isoproterenol nor (+/-)-norepinephrine at concentrations of 10(-6) M potentiated aldosterone release stimulated by angiotensin II or ACTH. These results suggest that catecholamines stimulate aldosteroidogenesis, but it appears unlikely that aldosterone release induced by ACTH or angiotensin-II is modulated by adrenergic stimulation.

Adrenal Cortex↗
PubMed1987

Diurnal rhythm of plasma immunoreactive corticotropin-releasing factor in normal subjects.

Plasma corticotropin-releasing factor (CRF), corticotropin (ACTH) and cortisol levels were simultaneously determined by radioimmunoassays at 0600 h, 1200 h, 1800 h and 2200 h in six normal subjects, in order to examine whether the diurnal rhythm in plasma CRF exists and how it correlates to the diurnal rhythm in plasma ACTH and cortisol concentration. The highest CRF level was observed at 0600 h (7.0 +/- 1.2 pg/ml) and significantly lower levels (p less than 0.01) at 1800 h (1.7 +/- 0.2 pg/ml) and 2200 h (1.9 +/- 0.4 pg/ml). A clear diurnal rhythm was demonstrated in plasma ACTH and cortisol levels, with the highest values at 0600 h (44.6 +/- 8.1 pg/ml and 15.9 +/- 2.0 micrograms/dl, respectively) and the lowest at 2200 h (12.3 +/- 2.8 pg/ml and 4.6 +/- 1.0 micrograms/ml, respectively). These results suggest that the diurnal rhythm in ACTH and cortisol is under the regulation, at least in part, of the diurnal rhythm in CRF secretion.

Adrenocorticotropic Hormone↗
PubMed1987

Superovulation in immature and mature Chinese hamsters.

Mature female Chinese hamsters ovulate an average of 8.8 +/- 1.0 (mean +/- SD) eggs per female in each estrous cycle. Superovulation can be induced in both immature and mature females by subcutaneous or intraperitoneal injections of pregnant mare serum gonadotropin (PMSG) and either human chorionic gonadotropin (hCG) or pituitary luteinizing hormone (PLH). The best superovulation in immature females was induced by the administration of 15 IU of PMSG followed 72 hr later by injection of 15 IU of hCG (about 25 eggs per female) or 0.2 mg (200 IU) PLH (about 46 eggs per female). Ovulation started about 13-15 hr after administration of hCG (or PLH) and was completed during the next 5-6 hr. Superovulation in mature females could be induced by injecting PMSG any day of the estrous cycle, but the best superovulation (about 39 eggs per female) was induced by injecting 15 IU of PMSG on day 1 (day of ovulation) followed by the injection of 0.4 mg of PLH 72 hr later. When immature females treated with the best superovulatory protocol were mated on the evening of PLH injection, only 5% of the eggs were found fertilized 50 hr after PLH administration. On the other hand, about 60% of the eggs were found fertilized in mature females mated following treatment with the best superovulatory protocol. The majority (83-85%) of superovulated eggs obtained from both immature and mature females were normally fertilized in vitro.

Aging↗