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Biomedical subjects

M Ohashi

Publications and source records attributed to M Ohashi.

At least 253 records · Page 14Linked to original sources
PubMed1991

Multiple subtypes of endothelin receptors in human and porcine tissues: characterization by ligand binding, affinity labeling, and regional distribution.

To characterize the properties and the distribution of endothelin (ET) receptor subtypes, we have examined the ligand selectivity and the molecular weight (Mr) of [125I]ET-1 and [125I]ET-3 binding sites in various tissues of human and pigs. ET-1 and ET-2 showed almost identical potencies in displacing the bound [125I]ET-1 in all of the tissues examined. ET-3, sarafotoxin S6b (SRTX-b), and sarafotoxin S6C (SRTX-c) displaced the [125I]ET-1 with nearly the same sensitivity as ET-1 (IC50 = 0.07-3.0 nM) in brain, kidney, liver, and adrenal, whereas the three peptides showed very weak competition (IC50 = 40-500 nM) against [125I]ET-1 binding in atria, aorta, lung, stomach, and uterus. The Bmax value for [125I]ET-3 was 83% of that for [125I]ET-1 in human liver membranes, whereas the Bmax for [125I]ET-3 was only 12% of that for [125I]ET-1 in human atrial membranes. [125I]ET-3 bound to liver and atrial membranes was displaced by ET/SRTX isopeptides almost equipotently. Two proteins with Mr of 110 and 50 kDa were specifically affinity-labeled with [125I]ET-1 in porcine lung membranes. The above findings indicated that two distinct subclasses of ET receptors, namely ET-1/ET-2-specific and ET/SRT family common receptors, were distributed in various proportions in mammalian tissues.

Affinity Labels↗
PubMed1991

Purification of a human centromere antigen (CENP-B) and application of DNA immunoprecipitation to quantitative assay for anti-CENP-B antibodies.

Centromere protein-B (CENP-B) was purified from HeLa nuclear extract by using a combination of Q-sepharose ion change and oligonucleotide sepharose column chromatography. CENP-B was purified more than 10,000 times and was analyzed by immunoblotting and DNA immunoprecipitation. Purified CENP-B was used as an antigen to develop DNA immunoprecipitation for rapid and specific detection of anti-CENP-B antibody in human sera. In this analysis, none of the tested sera immunoprecipitated DNA alone. All of the 40 anticentromere antibody (ACA)-positive sera immunoprecipitated CENP-B-alphoid DNA fragment complex, whereas 10 healthy control sera and 10 other autoantibody positive sera did not. Five of the ACA-positive sera, which did not show reactivity of CENP-B in immunoblotting analysis, immunoprecipitated CENP-B-DNA complex. In some sera antigenicity to CENP-B may be weakened by denaturation.

Autoantibodies↗
PubMed1991

Functional analysis of HLA-DR-expressing keratinocytes from tuberculin reactive skin.

We examined the functional roles of HLA-DR+ keratinocytes which were induced in vivo from tuberculin reactive skin. At 4 days after intradermal PPD injection, about 80% of keratinocytes obtained from the tuberculin reactive area expressed DR antigens. In 14 of 18 individuals examined, PPD-pulsed DR+ keratinocyte fraction induced autologous T-cell proliferation. The proliferative response was PPD-dependent, antigen specific; it depended upon DR expression by the keratinocyte fraction, because it did not occur in the presence of the PPD-nonpulsed DR+ keratinocyte fraction and was completely blocked by mouse monoclonal antibody to HLA-DR. However, the antigen-presenting capacity of the DR+ keratinocyte fraction appeared to be less than that of monocytes or the DR+ epidermal cell fraction. The DR+ keratinocyte fraction was also able to stimulate allogeneic T-cell DNA synthesis, but the DR- keratinocyte fraction could not. The possible influences of contaminant Langerhans cells and mononuclear cells in the DR+ keratinocyte fraction were considered to be unlikely. These results suggest that DR+ keratinocytes, which are induced in vivo, can both present the antigen to autologous T cells and stimulate allogeneic T cells.

Cell Division↗
PubMed1991

[Species and serovar distribution, and drug resistance of Shigella strains isolated from imported and domestic cases in 1980-1989 in Tokyo].

A total of 1,189 Shigella strains consisting 804 imported and 385 domestic strains were examined for their species and serovar distribution, and their drug-resistance. In both imported and domestic strains, S. sonnei was found to be the most prevalent species, followed by S. flexneri, S. boydii and S. dysenteriae in order. In imported strains, however, the isolation frequency of S. flexneri, S. boydii and S. dysenteriae were higher than that of domestic strains, and the serovar of each species was distributed in a wider range than that of the domestic strains. The drug resistance test using chloramphenicol (CP), tetracycline (TC), streptomycin (SM), kanamycin (KM), ampicillin (ABPC), sulfamethoxazole-trimethoprim (ST), nalidixic acid (NA), fosfomycin (FOM) and norfloxacin (NFLX) showed that 80.1% of the imported strains and 82.9% of the domestic strains were resistant to any of drugs examined, although frequency of resistance varied by their species. The frequency of resistance to each drugs were SM (74.0%), TC (68.5%), CP (38.8%), ABPC (35.3%), ST (34.1%), NA (1.5%) and KM (1.0%) in imported strains, and TC (79.2%), SM (55.3%), ABPC (40.3%), CP (38.4%), ST (32.4%), NA (30.5%) and KM (4.2%) in domestic strains. No strain resistant to FOM or NFLX was found in both groups. The resistance patterns varied to 32 types. Among those, a multiple drug-resistance type with CP.TC.SM.ABPC was found most frequently in both groups. Frequency of strains carrying transferable R plasmid was tested for 50 strains isolated in 1989 and three (6%) of them had the plasmid.

Ampicillin Resistance↗
PubMed1991

Decreased expression of cytochrome P450 17 alpha-hydroxylase mRNA in senescent bovine adrenal gland.

To investigate the mechanisms of age-related decline in synthesis of adrenal androgen, we studied the contents of cortisol (F) and dehydroepiandrosterone (DHEA) and the amounts of cytochrome P450 17 alpha-hydroxylase (P450c17) mRNA and cytochrome P450 11 beta-hydroxylase (P450c11) mRNA in young (1 year old) and senescent (10-12 years old) bovine adrenal glands. We also examined effects of ACTH (10(-7) M) on the secretion of F and DHEA and on the induction of P450c17 and P450c11 mRNA expression in cultured adrenal cells from young and aged cows. The content of DHEA in adrenal glands and the secretion of DHEA in response to ACTH in cultured adrenal cells from senescent cow were lower than those from young cow, while the content and ACTH-stimulated secretion of F in senescent adrenals were of a similar level to those in young adrenals. The adrenal gland from aged cow showed a significantly lower level of P450c17 mRNA compared with young bovine adrenal. However, P450c11 mRNA was expressed in senescent adrenal glands at the same level as that in young adrenals. The induction of P450c17 mRNA by ACTH (10(-7) M for 24 h) in cultured adrenal cells from aged cow also showed a decline compared with that from young cow, although there was no difference the ACTH-induced accumulation of P450c11 mRNA in cultured adrenal cells between young and senescent cow. These results suggested that the expression of P450c17 mRNA decreased in aged bovine adrenal, which may cause the age-associated decline in biosynthesis of adrenal androgen.

Adrenal Glands↗
PubMed1991

Antibacterial activity of a new tetracyclic quinolone, No. 5290, against norfloxacin- and ciprofloxacin-resistant strains of Staphylococcus aureus.

The antibacterial activity of a new tetracyclic quinolone, No. 5290, against 25 strains of Staphylococcus aureus clinically isolated in Japan in 1988-1989 was determined. The minimum inhibitory concentrations (MICs) of No. 5290 against both quinolone-susceptible (MIC: norfloxacin less than or equal to 6.25 micrograms/ml, ciprofloxacin less than or equal to 1.56 micrograms/ml) and 4 out of 5 norfloxacin- and ciprofloxacin-moderately resistant strains (MIC: 25 micrograms/ml less than or equal to norfloxacin less than or equal to 50 micrograms/ml, 3.13 micrograms/ml less than or equal to ciprofloxacin less than or equal to 12.5 micrograms/ml) were 0.05 micrograms/ml. Similar findings were obtained on the quinolone-resistant mutants derived by norfloxacin- or KB-5246-selection from quinolone-susceptible clinical isolates of S. aureus. The uptake of No. 5290 into a quinolone-susceptible strain of S. aureus was 2.47 micrograms/mg dry cell and the uptake in norfloxacin- and ciprofloxacin-moderately resistant strains was comparable to that in the quinolone-susceptible strain. The uptake of No. 5290 in both the quinolone-susceptible strain, and norfloxacin- and ciprofloxacin-moderately resistant, and No. 5290-susceptible strains was only slightly influenced by the treatment of bacteria with carbonyl cyanide m-chlorophenylhydrazone. These findings indicate that: (i) No. 5290 has potent antibacterial activity against quinolone-susceptible strains of S. aureus, and the potent activity might be due to a high uptake caused by an ineffective efflux of No. 5290. (ii) No. 5290 also has potent antibacterial activity against norfloxacin- and ciprofloxacin-moderately resistant strains, the reason for which could not be explained by the efflux.

Anti-Infective Agents↗
PubMed1991

Evidence for the secretion of inhibin-like immunoreactivity from cultured human adrenal cells.

We have studied the production and release of inhibin-like immunoreactivity in the human adrenal gland. Extract of human adrenal glands showed a displacement curve paralleled with the inhibin standard. Inhibin-like immunoreactivity contents in the adrenal gland was 1893 +/- 474 (mean +/- S.D.) IU/g wet weight tissue. ACTH stimulated the secretion of inhibin-like immunoreactivity as well as cortisol and aldosterone in a dose-dependent manner in the cultured adrenal cells. These results indicate that the human adrenal gland produces and secretes inhibin-like peptide in response to ACTH.

Adrenal Glands↗
PubMed1991

Decreased binding capacity for alpha-human atrial natriuretic peptide in aldosterone-producing adrenocortical adenoma.

The previous study demonstrated that the aldosterone secretion of aldosterone-producing adrenocortical adenoma failed to be suppressed by human atrial natriuretic peptide, based on the data in synthetic alpha-human atrial natriuretic peptide infusion in vivo and the effect on in vitro secretion from cultured adenoma cells. Using the membrane fractions prepared from human adrenal tissues and an aldosterone-producing adenoma tissues, we characterized the binding sites for [125I] alpha-human atrial natriuretic peptide by the binding study and affinity-labeling of [125I] alpha-human atrial natriuretic peptide. Both normal adrenal and adenoma tissue membrane fractions possessed specific binding sites, however the relative binding capacity for [125I] alpha-human atrial natriuretic peptide in the adenoma preparations was markedly lower than that in the normal adrenal tissue preparation. The specific binding sites for [125I] alpha-human atrial natriuretic peptide were detected at the region of 140 KD and 67-70 KD only in the normal adrenal membrane fractions. Our data suggest that the refractoriness to the effect of atrial peptide may be due to the reduced receptor sites in aldosterone-producing adenoma cells.

Adenoma↗
PubMed1991

[A case of thyrotoxicosis with prolonged muscle cramp and hypocalcemia after treatment with methimazole].

We report a case of thyrotoxicosis with prolonged post-treatment muscle cramp and hypocalcemia. A 36 year-old woman with hyperthyroidism was treated with Methimazole (MMI). As plasma levels of T4 and T3 were normalized, hypocalcemia was noted and severe cramp of skeletal muscle appeared so that the patient was unable to walk. The cramp was gradually relieved as the levels of thyroid hormones re-increased by discontinuance of MMI, and recurred as the hormone levels were normalized by readministration of MMI. The plasma levels of free calcium ion was positively correlated with those of thyroid hormones, and the muscle cramp was worsened with lowering of the calcium level. Serum examination also revealed vitamin D-deficiency, which was probably due to an unbalanced diet of the patient. A therapeutic trial with 1 alpha-vitamin D3 and calcium lactate in addition to MMI improved both thyrotoxicosis and muscle cramp. These findings suggested that hypocalcemia due to vitamin D-deficiency was involved in the exceptionally prolonged muscle cramp associated with the treatment of hypothyroidism in this patient.

Adult↗
PubMed1991

[Juvenile dermatomyositis--statistical observation of 105 patients with dermatomyositis].

Statistical observation about the clinical items of 105 patients with dermatomyositis (DMS) attending Department of Dermatology, Nagoya University Hospital and some hospitals in Aichi Prefecture, during the year of 1965 to 1989, was carried out. Clinical features of the patients with juvenile DMS obtained from the observation were as follows. 1) The male:female ratio was 1.3:1 in juvenile DMS. The evident difference such as the predominance of females in adult DMS was not found. 2) The tendency that cutaneous manifestations usually preceded muscular manifestations was observed, and the muscular manifestations except severe symptoms were seen with a high incidence throughout the entire clinical course. 3) In the laboratory examinations, the incidence of elevation of serum aldolase concentrations in children was significantly higher than that in adults (p less than 0.05). Serum aldolase concentrations were usually elevated at onset or prior to the onset of muscular manifestations. Therefore the measurement of serum aldolase levels was considered to be useful for early diagnosis of juvenile DMS. The positive rate of antinuclear antibody in children was significantly lower than that in adults (p less than 0.001). 4) None of the children had any complications such as malignant tumors, interstitial pneumonia and pulmonary fibrosis, and none of them died. With regard to the outcome, the incidence of "remission or improvement" in children was significantly higher than that in adults (p less than 0.05). In the group of "same or worse", the children mainly had the cutaneous manifestations which were difficult to treat, compared with the adults. These results suggest that juvenile DMS may be a different disorder, probably a syndrome, from adult DMS.

Adolescent↗
PubMed1991

Absence of human brain natriuretic peptide in pheochromocytoma tissue.

We demonstrated that a novel natriuretic hormone, brain natriuretic peptide, modestly inhibited the production of cortisol and aldosterone stimulated by ACTH in cultured bovine adrenocortical cells. Moreover, the presence of brain natriuretic peptide was demonstrated in bovine adrenal medulla, suggesting that it may modulate adrenocortical steroidogenesis. Using a specific radioimmunoassay (RIA) for brain natriuretic peptide-26, we confirmed that human cardiac atrial tissues elaborated a considerable amount of brain natriuretic peptide-26-like immunoreactivity (1.00 +/- 0.17 micrograms/g wet weight tissue, n = 3). Its molecular form was similar to that of brain natriuretic peptide-32 and possibly, to gamma-brain natriuretic peptide. However, any immunoreactivity of brain natriuretic peptide could not be detected in human pheochromocytoma tissues and some tissues of the human central nervous system. These observations suggest that brain natriuretic peptide dose not function as a neuropeptide but that it may be a cardiac natriuretic hormone important in human physiology, involved in the balance of water and electrolytes.

Adrenal Gland Neoplasms↗
PubMed1991

Effect of insulin, glucagon or dexamethasone on the production of insulin-like growth factor I in cultured rat hepatocytes.

We studied the effect of insulin, glucagon or dexamethasone on the production of insulin-like growth factor I (IGF-I) by cultured rat hepatocytes. Hepatocytes were isolated from normal adult rat livers and cultured in MEM, as nearly confluent monolayers. In the absence of such hormones, IGF-I and albumin accumulated in the culture medium almost linearly for periods up to 24 hours with the accumulation rates of 140 mU/mg cell protein per hour and 1.2 micrograms/mg cell protein per hour, respectively. Cycloheximide (5 micrograms/ml) almost completely inhibited the accumulation of IGF-I and albumin in the medium. Insulin at concentrations over 10(-10) M significantly inhibited the production of IGF-I in spite of the increased production of albumin. Conversely, glucagon stimulated the production of IGF-I at concentrations over 10(-8) M, but inhibited the production of albumin at concentrations over 10(-10) M. Dexamethasone stimulated the production of IGF-I at concentrations over 10(-7) M, but had no significant effects on the production of albumin. Thus, IGF-I production of hepatocytes is regulated by several hormones with different manner from albumin production.

Animals↗
PubMed1990

Dual effects of staurosporine on arachidonic acid metabolism in rat peritoneal macrophages.

Staurosporine is a microbial anti-fungal alkaloid having a most potent inhibitory activity on protein kinase C and is recently found as a non-12-O-tetradecanoylphorbol-13-acetate (non-TPA)-type tumor promoter of mouse skin, although tumor promotion induced by a TPA-type tumor promoter teleocidin is suppressed by staurosporine. When rat peritoneal macrophages were incubated in the medium containing various concentrations of staurosporine, prostaglandin E2 production and release of radioactivity from [3H]arachidonic acid-labeled macrophages were stimulated at concentrations of 1 and 10 ng/ml. But higher concentrations of staurosporine such as 100 and 1000 ng/ml showed no stimulative effect on prostaglandin E2 production although cytoplasmic free calcium levels were increased in a dose-dependent manner. Staurosporine-induced stimulation of prostaglandin E2 production was inhibited by treatment with cycloheximide, suggesting that a certain protein synthesis is prerequisite for the stimulation of arahcidonic acid metabolism. At higher concentrations (100 and 1000 ng/ml), staurosporine inhibited TPA-type tumor promoter (TPA, teleocidin and aplysiatoxin)-induced stimulation of arachidonic acid metabolism probably due to the inhibition of protein kinases. Tumor promotion activity and anti-tumor promotion activity of staurosporine might be explained by the fact that the lower concentrations of staurosporine stimulate arachidonic acid metabolism and the higher concentrations of staurosporine inhibit the tumor promoter-induced arachidonic acid metabolism, respectively.

Alkaloids↗
PubMed1990

Identification and characterization of endothelin converting activity in cultured bovine endothelial cells.

Using a specific and sensitive radioimmunoassay (RIA) for the carboxyl terminal tail of endothelin (ET) (His16-Trp21), we have confirmed the presence of the converting activity from synthetic human big ET-1 to ET-1 in the homogenate of cultured bovine aortic endothelial cells. The optimal pHs for the converting activities were found at pH 3.0 and pH 7.0. The activity at pH 3.0 was completely inhibited by pepstatin A, whereas the activity at pH 7.0 was not affected by known various protease inhibitors except EDTA and EGTA. When the products from big ET-1 were analyzed on an ODS and a CN columns, only ET-1 was detected at pH 7.0, but various ET-like immunoreactivities other than ET-1 were detected at pH 3.0. These findings strongly suggest that mature ET-1 is formed from big ET-1 in the endothelial cells by a metal-dependent neutral protease.

Animals↗
PubMed1990

Regional distribution of endothelin receptor in porcine cardiovascular tissues.

To clarify effecting sites of endothelin (ET) in a circulation system, we have identified specific receptors for porcine ET(ET-1) and investigated the distribution in the porcine cardiovascular tissues. Scatchard analysis of 125I-porcine ET binding indicated the presence of a single class of high-affinity binding sites. The binding was highly specific for ET-1, because (1) none of the other various peptides or Ca2+-channel antagonists affected the binding, (2) the scission of disulfide bonds, the digestion of the C-terminal 6-amino acid residues, or nitrophenylsulfenylization of the C-terminal Trp21 of ET-1 markedly reduced the binding ability and, (3) ET-1 showed the highest affinity for the vascular receptor among three ET isopeptides. Cardiac atria possessed the highest density (2.7 pmol/mg protein) of ET receptors of all the tissues examined, including thoracic aorta, cardiac atria and cardiac ventriculi, basilar, renal, coronary and pulmonary branch arteries, coronary, renal and jugular veins, and small vessels of pia mater encephali. Small vessels, renal and coronary arteries also showed relatively high density (0.8-1.4 pmol/mg protein). Various veins examined also showed considerable density (0.45-0.74 pmol/mg protein). The apparent Kd of cardiac ET receptors (0.76 nM) was significantly greater than that of the receptors of the other tissue (0.06-0.14 nM). The extensive distribution and the local enrichment of ET receptor in a cardiovascular system strongly suggests that ET is one of the essential endogenous substances to control the tone of the vasculature.

Aged↗
PubMed1990

Cytotoxic effect of 1-methyl-4-phenylpyridinium ion on human melanoma cell lines, HMV-II and SK-MEL-44, is dependent on the melanin contents and caused by inhibition of mitochondrial electron transport.

MPP+, an oxidative metabolite of a neurotoxin, MPTP, was found to be cytotoxic to human melanoma cell lines, HMV-II and SK-MEL-44. After 3 days of culture in the presence of MPP+, a larger amount of MPP+ was accumulated in HMV-II cells than in SK-MEL-44 cells, which correlated well with the melanin contents; HMV-II cells contain larger amounts of melanin than SK-MEL-44 cells. After 6 days of culture in the presence of MPP+, the cytotoxicity of MPP+ on these cell types was evaluated by counting cell numbers with the dye exclusion test and double-layer soft agar clonogenic assay. It was found that exposure to MPP+ reduced the survival of HMV-II cells more significantly than that of SK-MEL-44 cells. In HMV-II cells, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was used to elucidate the mechanism of MPP+ lethality. The formazan formation was reduced markedly by the presence of MPP+ at concentrations much lower than those required for cell death. These results suggest that cytotoxicity of MPP+ may be ascribed to its accumulation due to high affinity for melanin, and to inhibition of the enzymes utilizing ubiquinone in the mitochondrial respiratory chain.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1990

Secretory protein 7B2. A novel tumor marker of medullary carcinoma of the thyroid.

Mean plasma concentrations of 7B2 in three patients with medullary carcinoma of the thyroid (MCT) (294 +/- 38 pg/ml) were significantly higher than those in age-matched normal subjects (107.2 +/- 7.2 pg/ml, n = 11). The intravenous infusions of pentagastrin (0.5 microgram/kg) markedly increased the plasma concentrations of 7B2 as well as calcitonin in all three MCT patients but it caused no significant rise of the plasma 7B2 concentration in any healthy subjects. The peak times and rates of increase of plasma 7B2 concentrations were different from those of plasma calcitonin concentrations in MCT patients. The plasma 7B2 concentration in one of the patients with MCT showed a marked reduction and no further elevation from the pentagastrin infusion following a total thyroidectomy (preop. 226 pg/ml; postop. 112.1 pg/ml). The above evidence suggests that the increased levels of plasma 7B2 in MCT patients may be attributed to the release from parafollicular cells of thyroid. Therefore, 7B2 is considered to be clinically useful as a tumor marker of MCT.

Adolescent↗