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Biomedical subjects

M Ohashi

Publications and source records attributed to M Ohashi.

At least 289 records · Page 16Linked to original sources
PubMed1989

Dose-excretion relationship in tetrachloroethylene-exposed workers and the effect of tetrachloroethylene co-exposure on trichloroethylene metabolism.

Personal monitoring of 8-hour time-weighted average intensity of exposure with diffuse samplers and analysis of shift-end urine for total trichloro-compounds (TTC) and other metabolites were conducted in two groups of workers in China, one (121 subjects) exposed to tetrachloroethylene (TETRA) alone, and the other (38 subjects) exposed to a mixture of TETRA and trichloroethylene (TRI). Urinalysis was also performed on samples from 103 non-exposed controls. A linear exposure-excretion relationship could be observed in both groups of workers. Comparison of these results with those of Japanese TETRA-workers suggested the presence of ethnic difference in TETRA metabolism. Urinary metabolite levels were markedly lower in the mixed (TETRA + TRI) exposure group as compared to previous findings in a group exposed to TRI alone. The observation indicates that metabolism of TRI is suppressed by the co-exposure to TETRA in humans.

Air Pollutants, Occupational↗
PubMed1989

Porcine brain natriuretic peptide receptor in bovine adrenal cortex.

The action of porcine brain natriuretic peptide (pBNP) on the steroidogenesis was investigated in cultured bovine adrenocortical cells. Porcine BNP induced a significant dose-dependent inhibition of both ACTH- and A II-stimulated aldosterone secretion. 10(-8) M and 10(-7) M pBNP also significantly inhibited ACTH-stimulated cortisol and dehydroepiandrosterone (DHEA) secretions. Binding studies of [125I]-pBNP to bovine adrenocortical membrane fractions showed that adrenal cortex had high-affinity and low-capacity pBNP binding sites, with a dissociation constant (Kd) of 1.70 x 10(-10) M and a maximal binding capacity (Bmax) of 19.9 fmol/mg protein. Finally, the 135 Kd radioactive band was specially visualized in the affinity labeling of bovine adrenal cortex with disuccinimidyl suberate (DSS). These results suggest that pBNP may have receptor-mediated suppressive actions on bovine adrenal steroidogenesis, similar to that in atrial natriuretic peptide (ANP).

Adrenal Cortex↗
PubMed1989

Levels of manganese in the urine of female farmers in non-polluted regions in Japan.

Nearly 1500 urine samples were collected from female farmers in eight regions widely scattered in the islands of Japan in the winter of 1987-1988. The samples were analysed for manganese by wet ashing and flameless atomic absorption spectrophotometry under strict quality control. The values observed after adjustment for a specific gravity of 1.016 were distributed log-normally with a geometric mean of 0.65 microgram/l and a geometric standard deviation of 2.47. There was no effect of aging or any effect of smoking on the urinary manganese concentration. The inter-regional difference may be present but not yet conclusive. As no sex difference was observed in a previous study, it may be possible to deduce that the value may possibly stand for the "background" level of both men and women, either smoking or non-smoking, among the general Japanese population. The observed value is discussed in comparison with values reported in the literature.

Agriculture↗
PubMed1989

Vaginal metastasis from transitional cell carcinoma of renal pelvis in horseshoe kidney.

We describe a case of transitional cell carcinoma of the renal pelvis in a horseshoe kidney with vaginal tumor as the first manifestation of remote metastasis. While the occurrence of adenocarcinoma in a horseshoe kidney appears to be no higher than in nonfused kidneys, the incidence of transitional cell carcinoma among neoplasms in horseshoe kidneys is higher. Vaginal metastasis from transitional cell carcinoma of the renal pelvis is considered extremely rare. To our knowledge, this is the first case reported of transitional cell carcinoma of the renal pelvis in a horseshoe kidney with metastasis to the vagina. The patient was successfully treated with surgery, irradiation, and chemotherapy.

Carcinoma, Transitional Cell↗
PubMed1989

Platelet-activating factor stimulates secretion of respiratory glycoconjugate from human airways in culture.

Platelet-activating factor (PAF) is a naturally occurring phospholipid that acts as a potent mediator of inflammation and bronchoconstriction. Since mucus secretion accompanies many pulmonary-allergic reactions, we examined the effect of PAF on respiratory glycoconjugate (RGC) release from human airways in vitro. PAF, in concentrations of 5 to 100 ng/ml, induced a specific, dose-dependent release of [3H]RGC from human airways in vitro (range of 15% to 120% increase above control, p less than 0.001; n = 8). Time-course studies revealed that RGC release reached its peak level by 60 minutes, and by the end of 4 hours, decreased almost to the baseline level, suggesting a stimulatory effect on secretion rather than synthesis. PAF analog, RO 19-3704, which is a PAF-receptor antagonist, inhibited RGC secretion mediated by PAF in a dose-dependent manner with an inhibitory concentration of 50% of 70 ng/ml. BW 755C and nordihydroguaiaretic acid, but not indomethacin, inhibited RGC release by PAF. LY 171883, a specific leukotriene D4-receptor antagonist, totally inhibited the release of RGC by PAF. Similar results were observed with FPL 55712. PAF-treated airways generated peptidoleukotrienes significantly above control airways in association with enhanced RGC secretion. This enhanced effect on RGC secretion was specifically and significantly blocked by LY 171883. Atropine (10(-5) mol/L) augmented the secretagogue activity of PAF, whereas dexamethasone (10(-5) mol/L) inhibited it. These data indicate that PAF is a significant RGC secretagogue that affects the RGC-secreting cells via the lipoxygenase pathway of arachidonic acid metabolism and the generation of leukotrienes in the airways, but not through the cholinergic receptors on the secretory cells.

Arachidonic Acids↗
PubMed1989

Cardiovascular, renal and endocrine effects of alpha-human atrial natriuretic peptide in patients with Cushing's syndrome and primary aldosteronism.

The pharmacological effects of synthetic alpha-human atrial natriuretic peptide (alpha-hANP) in patients with Cushing's syndrome and primary aldosteronism were compared with those in normal volunteers. An infusion of synthetic alpha-hANP at 0.1 microgram/kg per min for 20 min produced a maximal plasma hANP level of 800-1200 pg/ml in patients with Cushing's syndrome and primary aldosteronism, and in normal subjects. There were significant decreases in the mean blood pressure (-10 to -15 mmHg) in patients with Cushing's syndrome and primary aldosteronism, similar to those in normal subjects. The plasma cyclic 3'5'-guanosine monophosphate (cGMP) concentrations of both groups of patients were increased fivefold over the baseline level following the infusion. Infusion of synthetic alpha-hANP caused a greater increase in the rate of sodium excretion in patients with Cushing's syndrome and primary aldosteronism compared with normal volunteers. The plasma cortisol and aldosterone concentrations did not, however, significantly change during alpha-hANP infusion in either the patients with Cushing's syndrome or those with primary aldosteronism. As synthetic alpha-hANP has a potent hypotensive effect in hypertensive patients with Cushing's syndrome and primary aldosteronism, a significant reduction in blood pressure and natriuresis seems to occur without affecting adrenocortical steroidogenesis.

Adult↗
PubMed1989

Neonatal lupus syndrome and microtubular structure.

A female infant, at 6 weeks old, with the clinical manifestation of annular erythemas on the trunk and face, was positive for anti-SS-A and anti-SS-B antibodies. The annular erythema disappeared spontaneously at the age of 7 months when anti-SS-A and anti-SS-B antibodies were negative. Electron microscopic observation of the vascular endothelial cells on the annular erythema revealed microtubular structures. Later microtubular structures were found absent from the vascular endothelial cells of the area where the annular erythema had disappeared. The patient's mother is suffering from Sjögren's syndrome; she has no clinical symptoms but anti-SS-A and anti-SS-B antibodies are positive and a biopsy of small salivary glands of the lip demonstrated a marked periductal mononuclear cell infiltration. Microtubular structures were observed in her vascular endothelial cells in the small salivary gland region. These findings suggest that disappearance of microtubular structure may have some relationship with anti-SS-A and anti-SS-B antibodies.

Antibodies, Antinuclear↗
PubMed1989

Prevalence of small round structured virus infections in acute gastroenteritis outbreaks in Tokyo.

During the three-year period from 1984 to 1987, 506 acute gastroenteritis outbreaks involving 14,383 patients were reported to the Bureau of Public Health, Tokyo Metropolitan Government. Eighty (4,324 patients) of 150 outbreaks (4,860 patients) from which etiologic agents were not identified were subjected to virological investigation. Spherical particles of 28-32 nm in diameter with capsomere-like structures on the surface were detected in patients' stool specimens. Buoyant density of the particles appeared to be 1.36 to 1.40 g/ml in CsCl. Seroconversion to the particles was observed in patients by immune electron microscopy. From these observations, we concluded that the detected particles were members of small round structured virus (SRSV), and that they were implicated in the etiologically ill-defined outbreaks encountered. Prevalence of SRSV infections in these outbreaks was examined by electron microscopy. SRSV was positive in 83.8% of the outbreaks, and 96.4% of the cases. SRSV-positive outbreaks usually occurred during winter in contrast to bacterial outbreaks which often occurred in the summer season. Of 80 outbreaks examined, 53 were associated with the ingestion of oysters, and the remaining 27 mostly with food other than oysters. Oyster-associated outbreaks usually occurred on a small scale, while unassociated ones on diverse scales ranged from family clusters to large outbreaks.

Acute Disease↗
PubMed1989

Effect of porcine brain natriuretic peptide (pBNP) on human adrenocortical steroidogenesis.

Porcine brain natriuretic peptide (pBNP), purified from porcine brain, had a significant suppressive effect on aldosterone and cortisol secretions in ACTH-treated cultured human adrenal cells. Concomitantly, the intracellular cGMP formation was enhanced by pBNP treatment. A specific pBNP receptor was identified in the human adrenal tissues. Affinity labelling of 125I-pBNP showed two separate molecular weights of specific binding sites for pBNP of 140 and 67 kDa. A 125I-pBNP binding study of the human adrenal membrane fraction demonstrated the presence of high-affinity and low-capacity binding sites for pBNP. Moreover, these binding sites for 125I-pBNP were displaced by unlabelled alpha-rANP as well as pBNP. From these studies, we concluded that pBNP had suppressive effects on human adrenocortical steroidogensis, possibly via a receptor which may be shared with ANP.

Adrenal Cortex↗
PubMed1989

[Enteroinvasive Escherichia coli O29:H--isolated from travellers' diarrheal cases].

Escherichia coli strains isolated in Tokyo from stool cultures of two sporadic diarrheal cases of travellers returning from South America and Thailand in 1985 and 1987 respectively, were found to be enteroinvasive strains with rare serotype O29:H--. These E. coli O29:H-- strains showed typical biochemical reactions of enteroinvasive E. coli in that they were negative lysine decarboxylase and non-motile. They were positive for Serèny test with guinea pig eye, cell-invasion test with HeLa cells, 140 megadalton virulence plasmid, and the virulence-plasmid encoded outermembrane protein, indicating that these strains were pathogenic and may cause a Shigella-like disease. Although the same serotype strains have been isolated in other countries, this may be the first report of isolation in Japan.

Diarrhea↗
PubMed1989

[Serovars, antimicrobial resistance and conjugative R plasmids of Salmonella isolated from human during the period of 1966-1986 in Tokyo. Research Group for Infectious Enteric Diseases].

We examined 4,739 isolates of Salmonella isolated from patients with gastroenteritis during the period of 1966-1986 in Tokyo for the incidences of serovars, antibiotic resistance and conjugative R plasmids. The period of study was divided into three: 1966-73 (early period), 1974-79 (middle period), and 1980-86 (late period). The predominant serovars were S. typhimurium (34.3%), Infantis (5.6%), Panama (4.9%) in the middle period, S. typhimurium (31.7%), Paratyphi B (9.4%), Litchfield (7.3%) in the late period. These results were consistent with serovars of isolates from healthy citizens. The frequency of resistant isolates was as high as 86.9% in the early period, mostly streptomycin (SM)- and tetracycline (TC)-resistant isolates, but decreased significantly in the middle and the late periods, to 53.3 and 39.4%, respectively. The percentages of ampicillin (ABPC)-, chloramphenicol (CP)-, and kanamycin (KM)-resistant isolates increased in the late period. Strains carrying conjugative R plasmids were isolated as frequently as 57.8% of the total isolates in 1973, but as less frequently as 6.7% in 1981 indicating that the rate was roughly proportional to the incidence of the drug resistant isolates. The rate, however, increased gradually after 1981. The predominant resistance pattern of the R plasmids was TC-resistance in the early period, gradually changed into multiple and finally to AP-, CP-, KM-, SM-, TC- and sulfonamides-resistance in the late period.

Conjugation, Genetic↗
PubMed1989

Western blot (immunoblot) assay of small, round-structured virus associated with an acute gastroenteritis outbreak in Tokyo.

Small, round-structured virus (SRSV) was detected in a stool specimen of a patient during an acute gastroenteritis outbreak in Tokyo and was tentatively named SRSV-9. SRSV-9 was purified by sucrose velocity gradient centrifugation after CsCl density gradient centrifugation. The buoyant density of SRSV-9 appeared to be 1.36 g/ml in CsCl. A Western blot (immunoblot) assay using the biotin-avidin system revealed that SRSV-9 was antigenically related to the Hawaii agent but distinct from the Norwalk agent and contained a single major structural protein with a molecular size of 63.0 +/- 0.6 kilodaltons. The prevalence of SRSV-9 infection in Tokyo was surveyed by the Western blot antibody assay by using a crude virus preparation as the antigen. Seroconversion was observed in 56.5% of the patients involved in the outbreaks from which SRSV was detected by electron microscopy.

Acute Disease↗
PubMed1989

Growth hormone releasing hormone-sensitive adenylate cyclase activity in growth hormone-producing pituitary adenoma: correlation to the response of plasma growth hormone to growth hormone releasing hormone in patients with acromegaly.

The correlation between response of plasma GH to GHRH and the GHRH-induced stimulation of the intracellular adenylate cyclase (AC) activity in pituitary adenoma cell membranes in acromegalic patients was investigated. Each peak plasma GH level after iv administration of GHRH ranged from 1.1 to 13.8 times the basal level in 13 acromegalic patients. On the other hand, the maximal stimulation of intracellular AC activity (cAMP production) induced by GHRH varied from 1.4 to 6.4 times the control level in each GH-producing pituitary adenoma cell membrane. A significant positive correlation (r = 0.89, P less than 0.005) between plasma GH response to GHRH and intracellular cAMP production stimulated by GHRH was observed in nine of the acromegalic patients. In contrast, the response of plasma GH to GHRH was significantly blunted, despite a fairly large production of intracellular cAMP stimulated by GHRH, in the other four acromegalic patients. These results suggest that GHRH-induced GH release from GH-producing pituitary adenomas of patients with acromegaly may be regulated not only by GHRH receptor-adenylate cyclase system but also modified by several other factors including somatostatin and Sm-C.

Acromegaly↗
PubMed1989

LHRH increases plasma 7B2 concentration in normal human subjects.

We studied the response of plasma 7B2 to LHRH and ovine corticotropin releasing hormone (o-CRH) in healthy young subjects. The plasma 7B2 concentration significantly increased from 78.3 +/- 7.5 (mean +/- SEM) to 102.0 +/- 6.0 ng/L (142.7 +/- 12.7% of the basal value; P less than 0.01) following iv administration of LHRH in seven young subjects. On the other hand, no increase in plasma 7B2 was found after iv administration of o-CRH in six young subjects. These results, together with our previous report of no increase in plasma 7B2 after administration of TRH and GHRH in young subjects, suggest that pituitary 7B2 may be present in gonadotrophs and be released only by LHRH in physiological conditions.

Adrenocorticotropic Hormone↗
PubMed1989

Evidence for age-related change in plasma 19-hydroxyandrostenedione.

The steroid, 19-hydroxyandrost-4-ene-3, 17-dione (19-hydroxyandrostene-dione, 19-OH-A-dione) has been known to enhance the mineralocorticoid action of aldosterone. To investigate the age-related change in the plasma 19-OH-A-dione concentration, plasma 19-OH-A-dione, androst-4-ene-3, 17-dione (A-dione), aldosterone and cortisol of 38 non-hypertensive healthy subjects (18 young men and 20 aged men) measured by specific radioimmunoassays. The basal plasma 19-OH-A-dione and A-dione concentration in aged men was significantly lower than in young men (P less than 0.01). Moreover, there was found to be a positive correlation between plasma 19-OH-A-dione and A-dione (P less than 0.01). On the other hand, plasma aldosterone and cortisol in aged men showed a tendency to decrease, but no statistical significance compared to young men was observed. This study demonstrated that there was an apparent age-related decrease not only in plasma A-dione, but also in plasma 19-OH-A-dione, an amplifier or aldosterone action.

Adolescent↗
PubMed1989

Formation of hydroxyapatite in hydrogels from tetracalcium phosphate/dicalcium phosphate mixtures.

Apatitic calcium phosphate cements, formed by the ambient reaction of tetracalcium phosphate (TTCP) with dicalcium phosphates (DCP), have been recently reported. H2O or dilute aq. H3PO4 (0.2%) is used as the liquid vehicle for this reaction. The aim of this study was to ascertain if hydroxyapatite (HAp) can form in self-cured hydrogel composites containing TTCP/DCP mixes. The setting times (ST) and diametral tensile strengths (DTS) of these hydrogel composites were also determined. The hydrogels were of two types: (1) vinyl thermosets derived from the copolymerization of HEMA (2-hydroxyethyl methacrylate) and cross-linking monomers, and (2) polyelectrolyte-based hydrogels formed from aq. poly(alkenoic acids), e.g., poly(acrylic acid). Cylindrical specimens 6 mm D x 3 mm H were prepared and stored in H2O for up to 30 days. The HEMA composites were hardened in 7-15 min by free radical initiation (benzoyl peroxide/tertiary aromatic amine). The polyelectrolyte cements were hardened in 6-8 min. After various periods of storage in H2O at 37 degrees C, some of the specimens were examined by X-ray spectroscopy for HAp. HAp formation was not observed in the HEMA composites even after 30 days of H2O storage but was detected in the polyacid cements. The 24-h DTS values of the HEMA composites (14-26 MPa) were higher than those of the polyacid cements (7-12 MPa). Both the H2O content and pH may thus be factors controlling the rate and extent of HAp formation in hydrogel composites containing TTCP/DCP mixtures.

Calcium Phosphates↗
PubMed1989

Detection of lead in human teeth by exposure to aqueous sulfide solutions.

A recent study has shown that the presence of lead (Pb) as well as other base metals in esthetic restorative materials, especially dental cements, is detectable by color shifts induced by exposure of hardened specimens to a 0.1% (w/v) aqueous solution of sodium sulfide, Na2S. The present study was initiated to determine the applicability of this simple exposure test to the detection of Pb in human teeth. Extracted whole teeth as well as sectioned, thin specimens were exposed first to either a 0.01% or a 0.001% (w/v) aqueous solution of lead nitrate, Pb (NO3)2, at 37 degrees C for 24 h. After rinsing with distilled H2O and a subsequent 24 h exposure to the 0.1% Na2S solution at 37 degrees C, the tooth specimens were examined visually and by a dental color analyzer for color changes. The latter color measurements were evaluated by the Lab system of Hunter, and the color difference, delta E, was determined. Neither control specimens exposed to distilled H2O only or to 0.1% Na2S only exhibited any significant change in appearance after 24 h of storage at 37 degrees C. However, specimens exposed first to the Pb (NO3)2 solutions showed discernible delta E values after exposure to the Na2S solution. Delta E was greatest for specimens exposed to the more concentrated Pb (NO3)2 solution. Most of the discoloration in both thin and intact tooth specimens was confined to the outermost layers of the tooth structure. For the intact specimens, the greatest degree of discoloration occurred in the cementum, the most permeable part of the tooth structure.

Adult↗