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Biomedical subjects

M Ohashi

Publications and source records attributed to M Ohashi.

At least 307 records · Page 17Linked to original sources
PubMed1989

[Water sorption, solubility, MeOH sorption and THF sorption of visible light cured resin--on resin using cyclophosphazene monomers and commercial monomers].

Studies were done to decrease both the water sorption and solubility of visible light cured resin. As monomer, three kinds of cyclophosphazene monomers and three kinds of commercial monomers were prepared to the visible light cured unfilled resins. When these set products were immersed in water, MeOH and THF, water sorption and solubility in water, MeOH sorption and solubility in MeOH, THF sorption, and mechanical properties were examined. Water sorption was increased by degrees for all the monomers. In the cases of 4 PN-(EMA)8, 4 PN-(TF)1-(EMA)7, 4 PN-(TF)2-(EMA)6, Tri-EDMA, BMPEPP and Bis-GMA + Tri-EDMA, the value of solubility in water after 30 days, was 0.16, 0.20, 0.51, 0.65, 0.17 and 0.81% respectively. MeOH sorption showed a tendency to increase, except for Bis-GMA + Tri-EDMA and 4 PN-(TF)2-(EMA)6. Solubility in MeOH after 30 days, for cyclophosphazene monomers and commercial monomers, was 0.09-0.36% and 1.36-5.40%. THF sorption after 30 days, for cyclophosphazene monomers, was small in comparison with that of commercial monomers. Compressive strength was 230-275 MPa in all cases. But, transverse strength, for all the cyclophosphazene monomers, was 45 MPa or below. In the cases of commercial monomers, the value of transverse strength was 55-90 MPa.

Acrylic Resins↗
PubMed1989

Natural killer cells in inflammatory lesions and transplanted tumors in mouse skin.

The mode of natural killer (NK) cell migration to the sites of inflammation and transplanted tumors was investigated by using dry ice for physical irritation and 1-fluoro-2,4 dinitrobenzene (DNFB) for chemical irritation in mouse ear. In experiments with transplanted tumors, NK cell sensitive tumor cells (RL male 1) and insensitive tumor cells (p815) were transplanted into the ears of C3H and BALB/c mice, respectively. Employing a polyclonal rabbit antiserum against asialoGM1 (GA1), and a monoclonal rat antiserum against Thy-1 in an immunohistochemical double-staining technique, we enumerated the number of Thy-1-positive and asialoGM1-positive (Thy-1+ GA1+) cells and Thy-1-negative and asialoGM1-positive (Thy-1-GA1+) cells at various times of irritation. Following physical irritation, Thy-1-GA1+ cells (108.8 +/- 4.5/mm2 at 24 h and 71.2 +/- 3.8/mm2 at 48 h) were found in the epidermis, whereas Thy-1+GA1+ cells were not found. In delayed-type skin reaction by DNFB, Thy-1-GA1+ cells (87.1 +/- 5.8/mm2 at 24 h and 60.7 +/- 2.9/mm2 at 48 h) and Thy-1+GA1+ cells (26.4 +/- 3.6/mm2 at 24 h and 15.3 +/- 4.3/mm2 at 48 h) were found in the dermis. Since it was reported by previous investigators that Thy-1+GA1+ cells are NK cells, we assumed that NK cells infiltrated nonspecifically in the dermis in delayed-type skin reaction by DNFB. In the tumor transplant experiments, the GA1+ cells were found near both types of tumors, but they were in contact with RL male 1 and not with p815. Because it was reported that GA1+ monocytes do not have cytotoxicity against tumor cells, our findings suggest that GA1+ cells migrate nonspecifically to the sites of inflammation, and that the NK cells among them may make direct contact with the tumor cells when they encounter NK cell sensitive tumors.

Acute-Phase Reaction↗
PubMed1989

[An in vitro study of dentin hypersensitivity using calcium phosphate cement].

Calcium phosphate remineralizing slurry (CPRS), consisting of an equimolar mixture of tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD), has previously been shown to form hydroxyapatite (HAp) spontaneously at physiological pH. Since considerable amounts of HAp may be formed in situ by CPRS, it may be effective for desensitizing hypersensitive dentin by obturating exposed dentinal tubule openings. In the present study, the effects of topically applied CPRS to etched dentin surfaces were investigated. The samples were randomly divided into 3 groups: (1) the control specimens were soaked in a saliva-like (SL) solution (2) the specimens received either 10-minute or 1-hour treatment with CPRS and (3) the specimens were treated with viscous CPRS, containing carboxymethyl cellulose (CMC) gel, for 8 hours. The SEM observations revealed that the control specimens were covered with a thin layer of plate-like crystals indicative of octacalcium phosphate (OCP). No significant penetration of the crystals into the dentinal tubules was detected. In CPRS group, the 10-minute treatment produced a 10 to 15 microns thick dense layer of precipitation consisting of needle-, rod-, and plate-like crystals. The 1-hour treatment produced a similar precipitation except that the crystals were mostly needle-like. A cross section view of the samples indicated remarkable penetration of the crystals into the tubules, thus providing significant obturation of tubule openings. Samples in the CMC-gel group were covered with an even more impervious layer of precipitation consisting of crystals of a variety of morphologies.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Phosphates↗
PubMed1989

[Neoplastic angioendotheliosis: a case of T cell lymphoma positive for S-100 protein].

A 63-year-old woman presented with painless, firm, subcutaneous nodules on her legs and trunk. The lesions were annular or serpiginous and their surface was livid-red to pale-red. Superficial lymph nodes were not palpable. Upper gastrointestinal series, barium enema, Ga scintigraphy, and CT findings were negative. Histological examination revealed deep dermal vessels occupied by neoplastic cells and fibrin thrombi. We diagnosed her as having neoplastic angioendotheliosis. Electron microscopically, tumor cells lacked Weibel-Palade bodies. Immunohistochemically, the tumor cells were positive for leukocyte common antigen, T11, MT-1, HLA-DR and S-100 protein. They were negative for Factor VIII-related antigen, epithelial membrane antigen, carcinoembryonic antigen, B-1, and B-2. Immunoelectron microscopic study showed that their nuclei, cytoplasma, and cell membranes were positive for S-100 protein. Based on these findings, we diagnosed her as having T cell lymphoma. The patient rejected chemotherapy and was discharged. Three months after discharge, right hemiplegia developed. Brain CT scan revealed enhanced masses in the left frontal, temporal, and occipital lobes. Craniotomy showed only gliosis and hemorrhage. She died of cerebral bleeding three months after craniotomy.

Biomarkers, Tumor↗
PubMed1989

Metabolic fate of the new Ca++-channel blocking agent (+)-(2S,3S)-3-acetoxy-8-chloro-(2-(dimethylamino)ethyl)-2,3-dihydro- 2-(4-methoxyphenyl)-2,5-benzothiazepin-4-(5H)-one maleate. Distribution, excretion and protein binding in rats and dogs.

Distribution, excretion and protein binding of (+)-(2S,3S)-3-acetoxy-8-chloro-(2-(dimethylamino)ethyl)-2,3-dihydro- 2-(4-methoxyphenyl)-2,5-benzothiazepin-4-(5H)-one maleate (TA-3090) in rats and dogs were investigated after oral (30 mg/kg (rats), 2 mg/kg(dogs] and intravenous (3 mg/kg (rats), 0.2 mg/kg (dogs) administration of 14C-TA-3090. Plasma level of radioactivity in rats reached plateau (6.04 micrograms equiv. of TA-3090 free base/ml) 1 h after oral administration. The plateau level continued at least up to 6 h. The plasma concentration of the unchanged drug (free base) reached the maximum (425 ng/ml) at 45 min after oral administration, and then decreased with a half-life of 1.16 h. Plasma level of radioactivity after intravenous administration to rats rose gradually up to 1 h and thereafter it was kept constant for 6 h. Plasma concentration of the unchanged drug decreased with half-lives of 0.43 h (alpha phase) and 1.33 h (beta phase) after intravenous administration. In dogs, the peak level of plasma radioactivity after oral administration was 227 ng/ml at 1 h. The Cmax, Tmax and t1/2 of unchanged drug were 31 ng/ml, 1.34 h and 4.13 h, respectively. The plasma levels of total radioactivity and unchanged drug after intravenous administration to dogs were 146 and 142 ng/ml at 1 min, respectively. The t1/2 of the plasma radioactivity were 0.02 h (alpha) and 4.02 h (beta). Those of unchanged drug were 0.03 h (alpha) and 1.66 h (beta).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[The roles of proteinase production and germ tube formation in the invasion of Candida albicans into newborn mouse skin].

The pathogenic factors of Candida albicans involved in invasion of the skin were studied. Strains of C. albicans differing in their abilities to secrete proteinase in vitro and to produce germ tube were inoculated onto the skin surface of newborn mice, and the invasion of the yeast cells into the horny layer was examined by histological techniques. The strains capable of producing germ tubes could penetrate into the skin, but those incapable of germ tube formation could not. The penetration of the yeast cells into the skin was independent of the ability to secrete proteinase, but, once penetrated, Candida cells from the proteinase-producing strains proliferated more profusely than those of proteinase-deficient ones. The results suggested that the invasion of C. albicans into the skin consisted of two processes; penetration and proliferation of the yeast cells in the tissue. The former might depend on the ability of germ tube formation and the latter on the secretion of proteinase.

Animals↗
PubMed1988

Porcine brain natriuretic peptide, another modulator of bovine adrenocortical steroidogenesis.

Porcine brain natriuretic peptide (pBNP) significantly inhibited aldosterone production stimulated by an angiotensin II analog and ACTH-stimulated cortisol secretion, together with simultaneously increasing the formation of cGMP in dispersed bovine adrenocortical cells. Receptors for pBNP were identified in bovine adrenal gland using an in vitro receptor autoradiographic technique and studies of 125I-pBNP binding. In vitro receptor autoradiography demonstrated specific binding sites for 125I-pBNP in bovine adrenal cortex. Complete displacement of 125I-pBNP by unlabeled pBNP or human atrial natriuretic peptide (hANP) can take place at these sites. Analysis of 125I-pBNP binding to bovine adrenocortical membrane fractions showed that the adrenal cortex had high-affinity, low-capacity pBNP-binding sites, with a dissociation constant (Kd) of 2.32 +/- 0.33 x 10(-10) M (mean +/- SE) and a maximal binding capacity (Bmax) of 36.7 +/- 1.6 fmol/mg protein. Moreover, the specific binding sites for 125I-pBNP were completely displaced not only by unlabeled pBNP but also by unlabeled hANP. The hANP dose required for 50% inhibition of specific 125I-pBNP binding was almost identical to that for pBNP (IC50 values for hANP and pBNP: 8.5 x 10(-10) and 6.5 x 10(-10) M, respectively). These results suggest that pBNP exerts a suppressive effect on bovine adrenocortical steroidogenesis via a receptor which may be shared with ANP.

Adrenal Cortex↗
PubMed1988

An improved method of high-voltage isoelectric focusing on cellulose acetate membranes.

An apparatus and the procedure for cellulose acetate isoelectric focusing were refined and optimized for routine use in clinical laboratories. The space in the electrophoretic chamber was minimized to maintain high humidity during the run. The water content of the thin cellulose acetate membranes in the chamber was well controlled during isoelectric focusing and the effect of atmospheric carbon dioxide was also excluded. The temperature of the membranes was kept below 2 degrees C, even under conditions of high electric field strength for faster isoelectric focusing of high-molecular-weight proteins. No special training was required for technicians in clinical laboratories to obtain reproducible isoelectric profiles of human serum proteins.

Blood Proteins↗
PubMed1988

RU486 inhibits induction of aromatase by dexamethasone via glucocorticoid receptor in cultured human skin fibroblasts.

Effects of RU486 on the induction of aromatase by dexamethasone via glucocorticoid receptor were determined using cultured human skin fibroblasts. Competition of [3H]dexamethasone binding to the cytosol receptor was 7 times stronger with RU486 than with dexamethasone. The order of the strength of competition was RU486 greater than dexamethasone greater than betamethasone greater than prednisolone greater than hydrocortisone. RU486 abolished a specific 8.6 S [3H]dexamethasone binding peak in the cytosol, determined using a sucrose density gradient analysis. Dexamethasone markedly induced aromatase and this event was strongly suppressed by RU486, in a dose-dependent manner, in the cultured skin fibroblasts. A linear correlation between the strength of competition and the induction of aromatase of various glucocorticoids was observed. RU486 non-competitively inhibited aromatase induction by dexamethasone determined from a double reciprocal plot of aromatase activity, with respect to [3H]androstenedione concentration in the presence of RU486. These results show that RU486 is a peripheral noncompetitive antiglucocorticoid on aromatase induction by glucocorticoid in human skin fibroblasts and that aromatase induction is a good marker for the biological function of glucocorticoid receptor in human skin fibroblasts.

Aromatase Inhibitors↗
PubMed1988

Alpha-human atrial natriuretic polypeptide binding sites in human adrenal membrane fractions.

In a previous study evidence was presented that synthetic alpha-human atrial natriuretic polypeptide (alpha-hANP) significantly inhibits the secretion of aldosterone, cortisol, and dehydroepiandrosterone (DHEA) from cultured human adrenal cells. In the present work using crude membrane fractions prepared from human adrenal tissues obtained at autopsy, we noted the existence and molecular weight of specific binding sites for [125I]alpha-hANP. The mean maximal binding capacity (Bmax) and dissociation constant (Kd) of 4 human adrenal membrane fractions were 8.0 +/- 1.6 fmol/mg protein and 25.7 +/- 7.4 pM, respectively, as calculated by Scatchard plot analysis. The interaction of [125I]alpha-hANP with the high-affinity binding sites in human adrenal membrane fractions was unaffected by the addition of lysine vasopressin (LVP), somatostatin-14 and angiotensin-II (A-II). When the membrane fractions were incubated with [125I]alpha-hANP and then cross-linked with disuccinimidyl suberate (5 mM), the 67,000-Da protein was specifically radiolabeled. The very high affinity of [125I]alpha-hANP binding sites suggests that human adrenal steroidogenesis may be influenced by plasma levels of hANP, under physiological conditions.

Adrenal Glands↗
PubMed1988

Ca-entry blockers, verapamil and diltiazem, on alpha 1-adrenoceptors in thoracic aorta, renal artery and portal vein from rabbit.

1. Verapamil caused a parallel shift of the concentration-response curve for norepinephrine in rabbit thoracic aorta and the reduction in norepinephrine-induced maximum response with shifts of the concentration-response curve for norepinephrine in renal artery and portal vein. 2. Diltiazem was without any effects on the response of thoracic aorta to norepinephrine, while the responses of renal artery and portal vein to norepinephrine were inhibited noncompetitively by diltiazem. 3. Verapamil but not diltiazem diminished markedly dibenamine-induced inhibition of maximum response to norepinephrine in all the preparations used. 4. Specific bindings of [3H]prazosin to both the membrane fractions derived from thoracic aorta and renal artery were displaced concentration-dependently by verapamil and diltiazem, but the effective concentrations of diltiazem were more than those for Ca-entry blocking activity. 5. These results suggest that verapamil might antagonize norepinephrine at alpha 1-adrenoceptors and the effective concentration for Ca-entry blocking activity of diltiazem were less than those for the interaction of diltiazem with alpha 1-adrenoceptors.

Animals↗
PubMed1988

Ganglioside variations in human liver cirrhosis and hepatocellular carcinoma as shown by two-dimensional thin-layer chromatography.

Gangliosides isolated from 5 cases of normal liver tissues, 11 cases of liver cirrhosis and 5 cases of hepatocellular carcinoma were compared in their concentrations and compositions. Quantitative analysis revealed no significant change of ganglioside levels between normal and cirrhotic liver tissues or hepatocellular carcinoma. There was also no significant difference (p greater than 0.05) between cirrhotic liver tissues and hepatocellular carcinoma. Two dimensional thin-layer chromatography of the total ganglioside preparations of liver tissues from both liver cirrhosis and hepatocellular carcinoma showed proliferation of GM2, GD3, GD1 and at least two unidentified components, named provisionally spots Nos. 1 and 2 in the present report, and loss of GM3. Sialidase treatment and thin-layer chromatography showed the components of these spots to be sialidase-labile monosialogangliosides and distinctly different from GD3 which was described elsewhere.

Aged↗
PubMed1988

Adrenocortical tumor in a patient with untreated congenital adrenocortical hyperplasia owing to 21-hydroxylase deficiency: characterization of steroidogenic lesions.

We report a case of congenital adrenal hyperplasia complicated by a right adrenal adenoma. The congenital adrenal hyperplasia was confirmed by extremely high levels of basal serum 17 alpha-hydroxy-progesterone and urinary pregnantriol as well as an exaggerated response of 17 alpha-hydroxyprogesterone to adrenocorticotropic hormone. On roentogenographic examinations and an echogram a huge calcified tumor was seen in the right adrenal gland. Histological findings indicated an adrenocortical adenoma. Culture of the tumor cells showed an accentuated response in the ratio of 17 alpha-hydroxy-progesterone to desoxycortisol with adrenocorticotropic hormone as a stimulator, suggesting that such adenoma cells also lack 21-hydroxylase activity. Our study clearly demonstrates that tumor cells have the same steroidogenic lesions as hyperplasia.

Adenoma↗
PubMed1988

Human atrial natriuretic polypeptide in plasma of patients with anorexia nervosa.

To examine the effects of chronic dehydration and starvation on plasma levels of human atrial natriuretic polypeptide (hANP) in human subjects, the basal level and saline-induced rise of plasma hANP in 7 patients with anorexia nervosa were compared with those in age-matched healthy subjects. The unstimulated level of plasma hANP was markedly high in the patients with anorexia nervosa (patients vs. control; 55.4 +/- 9.0 pg/ml vs. 11.4 +/- 6.1 pg/ml, P less than 0.01). However, no significant increase of plasma hANP in the anorectic patients was observed in response to saline-infusion, while a 3-fold increase over the basal level of plasma hANP was noted in the saline-infused normal young subjects. These results show that hANP may be secreted to an inadequate extent, hence the release would be resistant to volume-loading. The pathophysiological meaning of such a high plasma concentrations of hANP in anorexia nervosa is the subject of ongoing studies.

Adolescent↗
PubMed1988

Immunohistochemical analysis of oral lichen-planus-like eruption in graft-versus-host disease after allogeneic bone marrow transplantation.

Immunohistochemical analysis of oral lichen-planus-like eruption (LPLE) in graft-versus-host disease (GVHD) using monoclonal antibodies (MoAbs) was performed on five patients after allogeneic bone marrow transplantation (BMT) for leukemia. In the mucosal lesions of LPLE in GVHD, the major population of infiltrated lymphocytes in the areas of upper lamina propria (Lp), basal cell layer (Bc), and epithelium above the basal cell layer (Ep) were T-cells (Leu-1+, Leu-4+) and expressed the phenotype associated with suppressor/cytotoxic T-cells (Leu-2a+) rather than helper/inducer T-cells (Leu-3a+). Some of the infiltrated lymphocytes in the areas of Lp, Bc, and satellite cell necrosis (SCN) bore interleukin-2 (IL-2) receptor. HLA-DR antigen was expressed on keratinocytes in the LPLE lesions. Immunoelectron micrographs showed various degrees of degeneration of keratinocytes to which Leu-2a+ cells attached, whereas those with accidentally attached Leu-3a+ cells preserved normal structures. These findings suggest that cellular immunity mediated by cytotoxic T-cells may play a major role in the pathogenesis of oral LPLE in GVHD.

Adult↗
PubMed1988

Lymphokine-activated killer (LAK) activity against autologous malignant tumors of the skin.

When peripheral blood mononuclear cells (PBMC) cultured with interleukin 2 (IL-2) develop the ability to lyse fresh tumor cells, such activity is referred to as lymphokine-activated killer (LAK) activity. In this paper, we examined LAK activity against the autologous skin tumors, malignant melanoma (MM), squamous cell carcinoma (SCC), and basal cell epithelioma (BCE), which have distinct clinical characteristics. Similar levels of LAK activity against Daudi 1A4, an NK resistant cell line were significantly obtained from all cancer patients. However, different levels of LAK activity against autologous tumor cells were found from three kinds of cancer patients using mixtures of autologous tumors and LAK. The levels of cytotoxicity were 29.8 +/- 7.0% in five MM, 15.9 +/- 4.9% in seven SCC, and 4.0 +/- 2.3% in five BCE patients at an effector/target ratio of 50/1. Allogeneic MM targets were lysed by LAK from all three types of cancer patients at similar levels, implying that LAK is not restricted to major histocompatibility complex (MHC) antigens. These results indicate that the levels of autologous LAK activity were significantly associated with the magnitude of clinical malignancy of the tumor targets, and suggested the selective lysis of tumor targets by LAK. NK activity of cancer patients bearing tumors was also examined prior to therapy. The levels of NK activity observed in MM patients were considerably lower than those in two other cancer patients.

Adult↗