Search PubMed⌕ Search

Biomedical subjects

A Masuda

Publications and source records attributed to A Masuda.

At least 289 records · Page 16Linked to original sources
PubMed1988

Treatment of acromegaly with long acting somatostatin analogue SMS 201-995.

Ten acromegalic patients were treated with the somatostatin analogue SMS 201-995 (SMS) for 3-38 weeks in various doses and by different administration routines (thrice daily or multiple sc injection). Plasma GH daily profiles, plasma IGF-I, urinary GH, serum TSH, IRI and fasting blood glucose (FBG) concentrations were measured before and during SMS treatment. Plasma GH rapidly decreased within one hour in all patients and was suppressed for at least 4 h after a 50 micrograms sc injection of SMS in 8 patients. Multiple injections of 300-600 micrograms/day SMS (25-50 micrograms X 12) suppressed GH throughout the day. Plasma IGF-I was completely normalized in 4 patients, and, in all but one of the others, decreased markedly. Urinary GH decreased within the first week of treatment in all patients and normalization was obtained in 3 patients. Shrinkage of the pituitary tumor, as determined by CT or MRI, was observed in 7 of 9 patients. Other clinical improvements, such as diminution or complete disappearance of swelling of soft tissues, excessive perspiration, and headache, were observed in 7 of 8 patients. Changes in serum TSH, IRI and FBG were seen in 3-4 patients, but without any apparent clinical problems. In conclusion, SMS is a useful clinical tool for treatment of acromegaly, and a multiple sc injection method seems to be preferable.

Acromegaly↗
PubMed1988

Estimation of peripheral chemoreceptor contribution to exercise hyperpnea in man.

Nine normal male subjects were studied at three levels of exercise (0, 40, and 80 W). Single vital capacity breath test was applied at rest and during exercise (phases 2 and 3). Minimum minute ventilation found within 4 breaths following the test was compared to the control value. Significant depression in minute ventilation was invariably observed. The minute ventilation was depressed more and more with increasing intensity of exercise. A significant difference was found between exercise and rest. However, the relative contribution of chemoreceptor activity remained the same 10-20% at all exercise levels. The magnitude of ventilatory depression (delta V resp) in phase 2 was larger than that in phase 3, when work rate increased to 80 W, both relative and absolute. A significant part of the exercise hyperpnea is due to peripheral chemoreceptor activity. The peripheral chemoreceptor activity is greater in phase 2 than in phase 3 at work rates of light to moderate intensity.

Adult↗
PubMed1988

Immunohistochemical study of Warthin's tumour with special regard to the germinal centre.

In order to analyze the role of the lymphoid stroma of Warthin's tumour, the author made an immunohistochemical study especially focussing on the germinal centre (GC). In the GCs, IgM and IgE were much more clearly observed in a lace-like network than other heavy chains, and also could be detected electron microscopically on the surface of GC cells and follicular dendritic cells (FDCs). Plasma cells scattered beneath the epithelial component were mainly positive for IgG and IgA. IgG-positive plasma cells were more predominant than IgA plasma cells. Among the cases examined, there was a significant difference in the number of IgE-positive GC and plasma cells. In the GCs five complement components (C1g, C4, C3c, C3d, C5) and complement receptors (C3bR and C3dR) were positive, displaying a lace-like pattern, which were proved, electron microscopically, to coincide with the surface of FDCs and GC cells. IgE-positive GCs showed the same result. DRC1, which specifically reacts to FDC-membrane, was located only in GCs, and electron microscope also revealed positive findings on the surface of FDCs. The above mentioned findings in the GC of Warthin's tumour were similar to those of lymph nodes except for the frequent distribution of IgE. Salivary amylase was seen in the GC on rare occasions, but was not positive on the surface of GC cells and FDCs. It is suggested that FDCs play an important role in immunological behaviour with complement and complement receptors in the GC of Warthin's tumour.

Adenolymphoma↗
PubMed1987

Characteristics of cell lines established from a mixed mesodermal tumor of the human ovary. Carcinomatous cells are changeable to sarcomatous cells.

Four clonal cell lines of two types were established from a heterotransplantable mixed mesodermal tumor of the human ovary. Biologic properties of these cell lines (designated CS-C1, CS-S1, CS-S2, and CS-S3) were examined. Cells of one line (CS-C1) had an epithelioid shape and grew in monolayers (C-type). The cells showed alkaline phosphatase activity, stained positively with antikeratin antiserum, and had an ultrastructure with carcinomatous characteristics. Cells of the other three cell lines (CS-S1, CS-S2, and CS-S3) had an irregular shape and grew in multilayers (S-type). Most of the cells did not show alkaline phosphatase activity. They stained, not with antikeratin antiserum, but in fibrillar array with antifibronectin antiserum. Their ultrastructure had sarcomatous characteristics. By low cell density cultures, S-type sublines arose from CS-C1 cell line, but no C-type sublines arose from CS-S1 cell line. These findings may support the theory of the combination tumor as the cytogenesis of mixed mesodermal tumor of the ovary; they also suggest the conversion of carcinomatous cells to sarcomatous cells.

Carcinoma↗
PubMed1987

The pathophysiological role of renal dopamine, kallikrein kinin and prostaglandin systems in essential hypertension.

In order to clarify the relationship and the pathophysiological role of renal dopamine, kallikrein-kinin and prostaglandin systems in essential hypertensives, the effects of dopamine on these systems and renal sodium handling were investigated. Basal levels of kallikrein, kinin and prostaglandin E2 in essential hypertensives were significantly lower than those in normotensives. Those of kallikrein and kinin were obviously more suppressed in the low renin group than in the normal renin group, but no significant difference in prostaglandin E2 was found in either subgroup. Urinary dopamine excretion was significantly lower in the low renin essential hypertensives, while no significant difference was found between normotensives and normal renin essential hypertensives. Kallikrein activity and prostaglandin E2 were significantly increased in essential hypertensives by dopamine infusion, and no significant difference was found in kallikrein-quantity and kinin between normotensives and essential hypertensives after the infusion. These increases of kallikrein and kinin were significantly higher in the low renin group than in normal renin group, but those of prostaglandin E2 were not. Urine volume, urinary sodium excretion and fractional excretions of sodium and inorganic phosphorus were all increased in both normotensives and essential hypertensives after dopamine infusion. The increases of these were significantly greater in essential hypertensives than in normotensives, and greater in the low renin group than the normal renin group. From these results, it was suggested that the dopamine, kallikrein-kinin and prostaglandin E2 system have a close relationship with each other, and the suppression of these systems may contribute to the pathophysiology of essential hypertension, especially in the low renin group.

Dinoprostone↗
PubMed1987

Effects of adrenergic blockers on corticotropin-releasing factor-induced behavioral changes in rats.

The effects of adrenoreceptor blocking agents on corticotropin-releasing factor (CRF)-induced behavioral changes in rats were examined. The i.c.v. injection of 1 micrograms ovine CRF significantly increased the grooming frequency, number of occurrences of rearing and total distance moved. I.c.v. administered phentolamine at a dose of 10 nmol completely suppressed the increase in rearing and total distance moved induced by CRF without affecting the grooming frequency, whereas 100 nmol phentolamine significantly decreased the grooming frequency as well as the rearing and total distance moved. In contrast, propranolol reduced the increase in rearing induced by CRF only at a dose which induced ataxia in rats. The increases in rearing and total distance moved induced by CRF were reduced by 10 nmol of yohimbine and 100 nmol of prazosin. S.c. injection of caffeine (10 mg/kg) produced a significant increase in grooming frequency, rearing, and total movement. Administration of 10 nmol phentolamine and yohimbine did not affect these behavioral changes induced by caffeine, while 100 nmol prazosin suppressed them. Therefore, prazosin depressed the behavior of rats non-specifically. These results suggest that CRF-induced behavioral hyperactivity is mediated at least in part by alpha-noradrenergic, mainly alpha 2-noradrenergic, systems in the brain.

Animals↗
PubMed1987

Effects of simultaneous treatment with various chemicals on BHA-induced development of rat forestomach hyperplasia--complete inhibition by diethylmaleate in a 5-week feeding study.

Male F344 rats were administered phenobarbital, polychlorinated biphenyl (PCB), retinol acetate, indomethacin, 6-amino-caproic acid, dexamethasone (DEX) or diethylmaleate (DEM) for one week and then were treated with these chemicals plus butylated hydroxyanisole (BHA) for a further four weeks. Histopathologically, the incidence of BHA-induced forestomach hyperplasia was significantly lower in rats treated with PCB, DEX or DEM than in those treated with BHA alone. However, the inhibition by PCB and DEX was only partial and might have been due to decreased food intake. On the other hand, DEM completely inhibited the hyperplastic response to BHA at a dose of 0.25%, and even at lower doses it demonstrated significant inhibition without any decrease in body weight or food intake. The result that DEM, a tissue glutathione depleting agent, can inhibit BHA-associated forestomach hyperplasia strongly suggests that tissue glutathione may be intimately involved in the induction of forestomach hyperplasia by the antioxidant in rats.

Aminocaproic Acid↗
PubMed1987

Enhancement of BHA-induced proliferative rat forestomach lesion development by simultaneous treatment with other antioxidants.

Synergistic effects of butylated hydroxyanisole (BHA) and other antioxidants on induction of rat forestomach lesions were investigated. Groups of F344 male rats were treated with 1% BHA plus 0.7% butylated hydroxytoluene (BHT), 1% BHA plus 1% propyl gallate (PG), 1% BHA plus 1% sodium L-ascorbate (SA), 1% BHA plus 1% DL-alpha-tocopherol (alpha-TP), 0.4% BHT plus 0.4% BHA plus 0.4% PG plus 0.4% SA plus 0.4% alpha-TP, 1% BHA or 2% BHA. Further groups of 10 rats each received antioxidants without BHA as controls. Histological examination revealed significantly increased incidences of hyperplasia in the groups given BHA together with SA or PG at the prefundic region or at the mid region respectively. The forestomach changes induced by BHA together with SA were equal to those induced by 2% BHA. On the other hand, simultaneous treatment with BHA and PG or alpha-TP reduced the incidence of hyperplasia at the prefundic region. It is concluded that mixed treatment with BHA and other antioxidants exerted enhancing or inhibitory effects on the induction of hyperplasia at different sites of the forestomach epithelium.

Animals↗
PubMed1987

Desensitization of rat pituitary somatotrophs to growth hormone-releasing factor occurs in vitro.

Desensitization of rat pituitary somatotrophs to human growth hormone-releasing factor (hGHRF) was investigated using cultured rat anterior pituitary cells. Growth hormone (GH) release decreased but the production of cAMP was still induced in response to subsequently added 10(-9) M hGHRF from cells pretreated with hGHRF at concentrations ranging from 10(-11) to 10(-7) M for 4 h. Desensitization to 10(-9) M hGHRF was also observed in cells pretreated with 10(-9) M hGHRF for 4 h in the presence of 2 mM EGTA, 10 ng/ml nifedipine or 10(-9) M somatostatin-28, which decreased GH release during pretreatment. Forskolin and A23187, at concentrations of 10(-6) M and 10(-4) M, respectively, stimulated GH release from cells pretreated with hGHRF to the same extent as that from the control cells. These results, therefore, suggest that desensitization to GHRF occurs regardless of the presence of releasable GH pool and that some changes such as uncoupling of GHRF receptors with adenylate cyclase and decreased sensitivity to cAMP of cAMP-dependent protein kinase of the secretory mechanism of GH, in addition to the decrease in releasable GH pool and down regulation of GHRF receptors, may be involved in the desensitization mechanism.

Animals↗
PubMed1987

The radioimmunoassay for human plasma atrial natriuretic peptide--its application to uremic patients.

A highly sensitive radioimmunoassay for alpha-human atrial natriuretic peptide (alpha-hANP) was established and applied to measure the human plasma alpha-hANP levels. In our assay system, anti-alpha-hANP antiserum was raised in albino rabbits by intradermally injecting synthetic alpha-hANP which was conjugated with bovine serum albumin. The final antiserum dilution was 1:50,000. Sensitivity was 2 pg/tube and the 50% intercept was at 28 pg/tube. The plasma alpha-hANP was extracted using a Sep-Pak C-18 cartridge. According to this procedure, the mean recovery was 73.8 +/- 3.4% (mean +/- SE). The averaged plasma levels of immunoreactive alpha-hANP (i alpha-hANP) in normal subjects were 24.8 +/- 2.1 pg/tube. In patients with chronic renal failure undergoing hemodialysis, the averaged plasma i alpha-hANP levels were 56.4 +/- 5.0 pg/ml before hemodialysis. Plasma i alpha-hANP levels were significantly higher in the patients with chronic renal failure than in the normal subjects. After hemodialysis, plasma i alpha-hANP levels decreased significantly (32.2 +/- 2.8 pg/ml). These results suggest that the alteration in extracellular fluid volume (ECFV) may affect the plasma levels of i alpha-hANP in patients with chronic renal failure under hemodialysis; i.e., an increase in ECFV elevates and a decrease in ECFV lowers the circulating levels of alpha-hANP.

Animals↗
PubMed1987

Role of renin-angiotensin and kallikrein-kinin systems on the mechanism of the hypotensive effects of converting enzyme inhibitor, alacepril.

In four patients with essential hypertension and one patient with renovascular hypertension, decreases in blood pressure and plasma angiotensin II levels, and increases in plasma renin activity and plasma kinin levels were observed during eight days of alacepril treatment. Significant correlations between the changes in mean arterial pressure and those in plasma angiotensin II or kinin levels were observed positively or negatively, respectively, in the essential hypertensives. These findings suggest that the hypotensive effect of alacepril might be caused mainly by a decrease in plasma angiotensin II levels and, at least in part, by an increase in plasma kinin levels.

Adult↗
PubMed1987

Ultrastructural localization of the 150/130 Kd antigens in sexual and asexual blood stages of Plasmodium falciparum-infected human erythrocytes.

The subcellular localization of the 150/130 Kd antigen in Plasmodium falciparum-infected erythrocytes was determined by electron microscopy using monoclonal antibody 9B11 and immuno-gold labeling. We now find that this antigen may be associated with the membrane of newly-infected human erythrocytes and the cytoplasm of ring stage parasites. During differentiation of the parasite to the trophozoite stage, the antigens are no longer detectable on the erythrocyte membrane, while gold particles become more numerous within the parasite and in the erythrocyte cytoplasm adjacent to the parasite. As the parasites develop into schizonts, more antigen appears within the parasites, and some of it appears in the erythrocyte cytoplasm. At the segmented schizont stage, many intraparasitic gold particles are associated with rhoptries and micronemes of developing merozoites. Likewise, gold particles are associated with elements of the rhoptry-microneme complex in free merozoites. No gold particles are detected on the surface of merozoites. These antigens are found most abundantly in erythrocytes infected with gametocytes, revealing a localization pattern similar to that of mature trophozoite-infected erythrocytes. These subcellular localization patterns are similar to those described for the ring-infected erythrocyte surface antigen.

Animals↗
PubMed1987

Induction of forestomach lesions in rats by oral administrations of naturally occurring antioxidants for 4 weeks.

The effects of naturally occurring antioxidants on rat forestomach epithelium were compared with those of synthetic antioxidants, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), of which the former is a known forestomach carcinogen. Groups of five F344 male rats were given diet containing BHA, BHT, gallic acid, syringic acid, sesamol, caffeic acid, chlorogenic acid, ferulic acid, eugenol or esculin for 4 weeks at a level of 0.7% for BHT or 2% for other compounds. Histological examination of the forestomach showed that BHA induced hyperplasia mainly in the prefundic region near the esophageal orifice, caffeic acid induced pronounced hyperplasia throughout the forestomach epithelium, and sesamol induced large ulcers and hyperplasia in the central region. Thus, these naturally occurring antioxidants showed different toxicities and abilities to induce hyperplasia in the rat forestomach.

Animals↗