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Biomedical subjects

Z Ota

Publications and source records attributed to Z Ota.

At least 127 records · Page 7Linked to original sources

Effects of dopamine on renal receptors for arginine vasopressin.

To determine whether dopamine would affect the arginine vasopressin (AVP) receptors in the kidney, and if so, which source of dopamine would predominantly affect them, changes in the AVP receptors of the rat kidney were measured under the conditions of chronic renal denervation and the chronic infusion of dopamine using the radiolabeled receptor assay (RRA) of [3H]-AVP. Denervation was performed by stripping the nerves from the renal artery and coating them with 10% phenol. Chronic denervation had no significant effect on either the affinity or maximum binding capacity of the renal AVP receptors, although diuresis was observed. The chronic infusion of dopamine using an osmotic minipump produced a decrease in the affinity of the AVP receptors. These observations indicate that dopamine may regulate the AVP receptors in rat kidney via circulating dopamine.

Animals↗

High resolution three-dimensional meshwork structure of the glomerular basement membrane.

To investigate the ultrastructure of the glomerular basement membrane (GBM), rat GBM was treated with sodium dodecyl sulfate and 2-mercaptoethanol and observed under an electron microscope employing ultrathin sectioning and rotary shadowing methods. Further, thick sections of the treated GBM were examined by high voltage transmission electron microscopy. A fine three-dimensional meshwork structure was clearly observed through the entire thickness of the GBM treated with sodium dodecyl sulfate and 2-mercaptoethanol by conventional transmission electron microscopy and high voltage transmission electron microscopy. The diameter of the fibrils forming the meshwork structure was about 3 nm and the dimensions of the pores present in the meshwork were 3 to 4 nm. The rotary shadowing technique revealed fine fibrils disentangled from the GBM that were bound together, and corresponded morphologically type IV collagen molecules. The present findings suggested that the GBM has a fine three-dimensional meshwork structure through its entire thickness which is composed mainly of type IV collagen and may function as a size barrier in the renal glomerulus.

Animals↗

Computerized approach using autoradiography to quantify atrial natriuretic peptide receptors in the DOCA-salt hypertensive rat kidney.

The alteration of atrial natriuretic peptide (ANP) receptors was investigated in the kidney of deoxycorticosterone acetate (DOCA)-salt treated hypertensive rats. The absolute amount of renal ANP receptors was determined in a membrane homogenate binding study of rat whole kidneys. Administration of DOCA-salt led to a decrease in renal ANP receptors after 3 weeks (prehypertensive state) and 6 weeks (established hypertensive state) of treatment. In vitro macro-autoradiography (ARG) was then performed with [125I]ANP to localize and to quantitate specific renal ANP receptors. ARG revealed that specific ANP binding was distributed mainly over the renal cortex with the inner medulla next in frequency. Renal ANP receptors were therefore quantified over the cortex and the inner medulla using the computerized microdensitometry of ARG. A significant reduction in renal ANP receptors was observed in the DOCA-salt treated rats after 3 and 6 weeks of treatment with decrements observed in both the cortex and inner medulla. These alterations may be related to the pathophysiology of hypertension.

Animals↗

Somatostatin receptors in the senescent rat brain: a quantitative autoradiographic study.

To examine the effects of aging on the density and distribution of somatostatin receptors (SS-R) in the rat brain, receptor autoradiography for SS-R was carried out in rats aged 3 and 24 months using 125I-labeled Tyr11-SS-14. Autoradiograms were quantitatively assessed by an image analyzer to evaluate changes in the expression of SS-R due to senescence. Statistically significant decreases in SS-R binding were found in specific regions of the brains of senescent rats as compared to young adult rats. The regions affected included the periaqueductal gray matter (73% loss versus young adult rats), the interpeduncular nucleus (73% loss), the pontine nucleus (63% loss), the superior colliculus (46% loss), the ventral tegmental area (46% loss), the temporal cortex (39% loss), the frontal cortex (34% loss), the hippocampus (33% loss), the amygdala (27% loss) and the claustrum (26% loss). There was no significant change in SS-R expression in the spinal cord with aging. Significant reductions in SS-R binding in these brain regions may be involved in the impairment of sensory and cognitive function that can occur with aging.

Aging↗

Cerebrospinal fluid and plasma corticotropin-releasing hormone in senile dementia.

Cerebrospinal fluid (CSF) levels of corticotropin-releasing hormone (CRH) and ACTH, and plasma levels of CRH, ACTH and cortisol were determined in samples taken simultaneously from 28 patients with dementia including senile dementia of the Alzheimer type (SDAT), multi-infarct dementia (MID), dementia following a cerebrovascular accident (CVD), and the borderline-to-normal state. CRH levels in CSF were significantly reduced in patients with SDAT and CVD, but not in those with MID, as compared with the borderline cases. ACTH levels in CSF were significantly reduced in the patients with SDAT compared to those with MID. Reduced CRH levels in CSF were found in the patients who showed severe dementia and poor activities of daily living (ADL). Plasma levels of CRH, ACTH and cortisol were normal and were not significantly different among the four groups of patients. CRH levels in CSF were positively correlated with ACTH levels in CSF, but not with the levels of plasma CRH, ACTH or cortisol. Plasma CRH levels were positively correlated with plasma ACTH levels. These results suggest that: 1) abnormalities in the extrahypothalamic CRH system play a role in the pathophysiology of senile dementia, which may not be specific to SDAT; 2) CSF CRH is correlated with the severity of dementia and ADL; 3) the levels of CRH in CSF and plasma are independent, and 4) the plasma CRH reflects, at least in part, the activity of the hypothalamic CRH regulating the secretion of pituitary ACTH.

Adrenocorticotropic Hormone↗

Hyperkinesia, plasma corticotropin releasing hormone and ACTH in senile dementia.

Senile dementia of the Alzheimer type (SDAT), in contrast to multi-infarct dementia (MID) was associated with delirium and marked increases in the number of walking steps taken during both the day and night. In SDAT patients, plasma ACTH levels in the afternoon and evening were higher but plasma corticotropin releasing hormone (CRH) levels in the evening were lower than in the MID patients. A positive correlation between ACTH levels and walking steps and a negative correlation between plasma levels of CRH and ACTH were found. These results suggest relevance of hyper-kinetic delirium to disruption of diurnal rhythm of the pituitary-adrenal axis, and a possible mechanism of the short feedback suppression of CRH release by increased circulating ACTH.

Adrenocorticotropic Hormone↗

Food deprivation decreases vasopressin mRNA in the supraoptic and paraventricular nuclei of the hypothalamus in rats.

We examined the effect of food deprivation for three days on hypothalamic arginine vasopressin (AVP) mRNA in rats. Simultaneously the effect of water deprivation for the same period was examined as a model of dehydration. Levels of AVP mRNA in the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) were determined by semiquantitative in situ hybridization histochemistry. Water deprivation increased AVP mRNA in both nuclei as previously reported. In contrast, food deprivation decreased AVP mRNA in these nuclei. The changes in AVP mRNA levels in the PVN were observed in the magnocellular subdivision of the nucleus. Plasma levels of ACTH and corticosterone were greatly increased in both treated groups of rats. Plasma AVP and osmolality levels were significantly elevated in water-deprived rats but not in food-deprived rats. These observations indicated that both food deprivation and water deprivation stimulated the pituitary-adrenal axis and that a reduction in AVP mRNA levels in food-deprived rats was caused by food deprivation but not by glucocorticoid feedback suppression nor by altered plasma osmolality.

Animals↗

Effect of a long-acting somatostatin analogue (SMS 201-995) on a growth hormone and thyroid stimulating hormone-producing pituitary tumor.

A 46-year-old woman with acromegaly and hyperthyroidism due to a pituitary adenoma. She had high serum thyroid-stimulating hormone (TSH) levels and very high serum growth hormone (GH) levels. Transsphenoidal removal of the tumor, post-operative irradiation, frontal craniotomy for removal of residual tumor and large-dose bromocriptine therapy were carried out consecutively. After therapy, serum GH levels gradually decreased, but not to the normal range, and serum TSH levels remained at inappropriately normal levels. Using immunoperoxidase techniques, GH-, TSH- and follicle-stimulating hormone (FSH)-containing cells were demonstrated in the adenoma. A long-acting somatostatin analogue (SMS 201-995, 600 micrograms/day) suppressed the serum GH level to the normal range with a concomitant suppression of TSH. Furthermore, the paradoxical serum GH responses to TRH and LH-RH were slightly improved. No important subjective side-effects were noted. Therefore, SMS 201-995 appeared to be a very effective drug in this patient with a GH- and TSH-producing pituitary tumor.

Acromegaly↗

Effects of beta-adrenergic blocking agents on specific binding of [3H]D-Ala2-Met5-enkephalinamide and [3H]naloxone.

To gain further insight into the central nervous system (CNS)-action of beta-adrenergic blocking agents (beta-blockers), we examined the effects of various kinds of beta-blockers on opioid receptors (Op-Rs) using radiolabeled receptor assay (RRA). We demonstrated that beta-blockers are competitively bound to Op-Rs in the CNS. Sodium index of beta-blockers in [3H]naloxone binding study indicated that beta-blockers had the mixed agonist-antagonist activity of opiates. The relative potency of beta-blockers in opioid RRA was negatively correlated with their membrane stabilizing activity. Neither beta-blocking activity nor intrinsic sympathomimetic activity was correlated with IC50 values of beta-blockers in opioid RRA. While it is widely accepted that beta-blockers have a tranquilizing activity, a part of the tranquilizing action of beta-blockers may be mediated through Op-Rs in the CNS. Although beta-blockers may have effects on their own receptors (beta-receptors) in the CNS, the more precise mechanisms of central action of these drugs must be further investigated.

Adrenergic beta-Antagonists↗

Complement activation pathways associated with islet cell surface antibody (ICSA) derived from child patients with insulin-dependent diabetes mellitus (IDDM).

We studied the pathways of complement activation associated with the islet cell surface antibody (ICSA) obtained from sera of 7 patients (age less than 15 years) with insulin dependent diabetes mellitus (IDDM). The target cells were 51CR labelled rat islet cells and the complement source was human AB serum. Complement-dependent antibody mediated cytotoxicity (CAMC activity) was obtained using the percentage of cytotoxicity. CAMC activity of untreated sera was significantly inhibited by treating with EGTA or EDTA (p less than 0.001). The CAMC activity of EDTA-treated sera was significantly lower than that of EGTA-treated sera (p less than 0.001). In the inactivated human AB serum, it was lower than that of EGTA-treated sera (p less than 0.05), but not different from that of EDTA-treated sera. These results show that the complement activation associated with ICSA in patients occurred not only via the classical pathway but also via the alternative pathway.

Antibody-Dependent Cell Cytotoxicity↗

A role of central alpha-1 adrenergic mechanism in shaking stress-induced ACTH and noradrenaline secretion.

The role of alpha-1 adrenergic mechanism in the shaking stress-induced adrenocorticotropic hormone (ACTH), and plasma noradrenaline secretion and pressor response were investigated using conscious rats. We also studied whether or not central corticotropin releasing hormone (CRH) is involved in the shaking stress-induced ACTH secretion. The shaking stress caused significant elevations of plasma ACTH, noradrenaline, and systolic blood pressure. Intra-third ventricular administration of alpha-1 adrenergic blocker, bunazosin, inhibited the shaking stress-induced ACTH secretion, but did not alter stress-induced noradrenaline secretion and pressor response. Furthermore, intra-third ventricular administration of CRH antagonist, alpha-helical CRH, significantly attenuated stress-induced ACTH secretion. These results indicate that alpha-1 adrenergic pathway and CRH at least partly mediate the shaking stress-induced ACTH secretion.

Adrenocorticotropic Hormone↗

A case of non-Hodgkin's lymphoma associated with hypercalcemia.

A patient with a diffuse, small cleaved cell, non-Hodgkin's lymphoma associated with marked hypecalcemia was described. Antibody to the adult T-cell leukemia-lymphoma virus was absent. Although bone marrow was infiltrated by lymphoma cells, destructive or lytic bone lesions could not be detected. The serum level of immunoreactive parathyroid hormone C-terminal (PTH-C) was normal. The serum level of 1, 25-dihydroxyvitamin D was lower than normal. This case suggests that other humoral substances produced by lymphoma cells may be responsible for hypercalcemia.

Humans↗

[Chronic administration of bifemelane hydrochloride increases somatostatin receptor binding in aged rat brain].

Changes in the distribution and densities of somatostatin receptors (SS-R) in young adult and aged rat brain and the effects of chronic administration of bifemelane hydrochloride (bifemelane) on these changes were studied by in vitro quantitative autoradiography of iodinated [Tyr11] SS-14. SS-R was highest in density in the amygdala, followed by the cingulate cortex, temporal cortex, frontal cortex, hippocampus and septal nucleus in the young adult rats. In contrast, SS-R binding was markedly reduced in the frontal cortex, temporal cortex, cingulate cortex, hippocampus, amygdala and septal nucleus of aged rats compared to young adult rats. However chronic administration of bifemelane significantly increased SS-R binding in the frontal cortex, temporal cortex, cingulate cortex, hippocampus and septal nucleus of aged rats without effects on young adult rats. This bifemelane-induced increase in SS-R is considered to have important implications in the mechanism of the therapeutic efficacy of bifemelane.

Aging↗

A membranous nephropathy associated with adult polycystic kidney disease.

A 53-year-old woman with adult polycystic kidney disease (PKD) developed a nephrotic syndrome. Evaluation of the renal biopsy specimens showed typical findings of membranous nephropathy (MN). There are few reports of nephrotic syndrome associated with PKD and only one proved to be MN. The possible mechanism of the association of PKD with MN was evaluated. Autoantibodies against the brush border were not detected in this patient's serum by indirect immunofluorescence. Three monoclonal antibodies against the tubular brush border and epithelial cell of distal tubulus did not react with subepithelial deposits in the biopsy specimen. Therefore tubular brush border antigen which was reported to induce membranous nephropathy was not detected in the immune complexes deposited in the glomeruli. So we could not determine any direct relationship between PKD and MN. The reaction of antibodies against basement membrane components (type IV collagen, laminin, fibronectin, heparansulfate proteoglycan) with the basement membranes of the cysts was evaluated by indirect immunofluorescence. The reaction with anti-heparansulfate proteoglycan antibody was decreased compared with normal tubular basement membrane. The reactivity to anti-fibronectin antibody was remarkably increased in the cystic walls, tubules, and interstitium. Changes of tubular basement membrane antigens was observed in PKD.

Antigen-Antibody Complex↗

[Effect of badoushuang on progressive glomerular sclerosis in rats with 7/8 nephrectomy].

Effect of Badoushuang (Semen crotonis pulveratum) was studied in the 7/8 nephrectomied rats, which we could establish as progressive glomerulosclerosis model in rats (Jap J Nephrol 32: 127, 1990). Badoushuang was administered into rats orally 60 mg/kg/day every day after 7/8 nephrectomy. As controls 7/8 nephrectomied rats were used. No adverse effect of Badoushuang were noted during 8 weeks of observation periods. Administration of Badoushuang, in rats with a remnant kidney, decreases urinary protein and lowers blood pressure, keeps creatinine clearance and lowers serum creatinine level and BUN. Morphologically glomerular hypertrophy, crescent formation and sclerosis were less in experimental treated rats. These results suggest Badoushuang ameliorates the progressive kidney disease of rats with subtotal renal ablation. Further study is necessary to clarify the effect of Basoushuang on progressive glomerular sclerosis.

Animals↗