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Biomedical subjects

M Tamura

Publications and source records attributed to M Tamura.

At least 865 records · Page 48Linked to original sources
PubMed1986

[Growth hormone-producing pituitary adenoma in an 8-year-old girl: case report].

A rare case of pituitary adenoma in childhood presenting as giantism is reported. A 6-year-old girl came to our attention in 1982 because of excessive growth noted since the age of 3 yr. Her appearance revealed giantism. She also had a 4 year history of genital bleeding, but no development of external genitalia nor mammary gland. Endocrinological studies revealed markedly elevated serum basal levels of both growth hormone (GH) and prolactin (PRL). She had a bromocriptine therapy for 1 year and 8 months, but it was difficult to suppress her excessive growth rate. So she was admitted at the age of 8 years to undergo the operation. Visual fields were intact. X-ray examination of the skull demonstrated a slightly enlarged sella turcica. Computerized tomography revealed an isodense mass at the pituitary fossa without extrasellar extention. Repeated endocrinological studies were carried out. Basal levels of GH and PRL were 43.8 ng/ml and 67 ng/ml. All other pituitary function were normal, except for puberal responses of luteinizing hormone (LH) and follicle stimulating hormone in LH-RH loading test. 50 g oral glucose tolerance test was normal. Transsphenoidal microsurgery was performed in August 1984. The tumor filled up the pituitary fossa with fibrous element. Histological examination disclosed a mixed adenoma, predominantly chromophobe, with a few granulated eosinophils. Immunoperoxidase staining was also performed on the adenoma. Most of the tumor cells stained for GH, and a few of them stained for PRL. Postoperatively hypopituitalism was not complicated. Surgery produced a decrease in serum PRL level under 20 ng/ml, but serum GH level was not enough reduced under 10 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1985

Photooxidation of porphyrin in Mg-substituted horseradish peroxidase.

Upon photoirradiation under aerobic conditions, the porphyrin prosthetic group in Mg-substituted horseradish peroxidase was oxidized to a mixture of its pi-cation radical and an oxidized product with an absorption band at 448 nm. The 448 nm compound was then converted to a 489 nm compound in the dark and the activation energy for the conversion was 19.3 kcal/mol. About 1 mol of O2 was consumed per mol of the 448 nm compound formed and no O2 consumption was seen in the dark reaction. The substitution of ethyl groups (meso) and hydroxyethyl groups (hemato) for the vinyl groups in protoporphyrin IX did not have an effect on the result. Under anaerobic conditions and in the presence of a suitable electron acceptor, the only photooxidation product of porphyrin was its pi-cation radical. The formation of hydroxyl radicals during irradiation under aerobic conditions was confirmed by the spin-trapping method. The formation of the above two radicals could be followed by ESR spectroscopy separately at a fixed magnetic field which was set to maximize each ESR signal. The rate of hydroxyl radical formation depended linearly on the concentration of Mg peroxidase. The photooxidation of porphyrin was slow and gave nonspecific product(s) when Mg protoporphyrin IX was present in the heme crevice of apomyoglobin or free in solution.

Electron Spin Resonance Spectroscopy↗
PubMed1985

The inhibitory effect of halides and carboxylates on hepatic NADH: cytochrome b5 oxidoreductase.

The inhibitory effect of several halides and carboxylates on bovine liver microsomal NADH: cytochrome b5 oxidoreductase (EC 1.6.2.2) was examined. The magnitude of inhibition was altered by various anion species but not by cation species. The order of effectiveness was F- less than acetate less than Cl- less than Br- less than I- less than succinate congruent to citrate. The kinetics of these inhibitions was competitive with cytochrome b5, and non-competitive with NADH, indicating that these anions inhibit the interaction of the enzyme with cytochrome b5.

Animals↗
PubMed1985

Identification of linoleic and oleic acids as endogenous Na+,K+-ATPase inhibitors from acute volume-expanded hog plasma.

Na+,K+-ATPase inhibitors have been found to exist in acutely saline-infused hog plasma, which also inhibit the specific binding of ouabain to Na+,K+-ATPase and the binding of digoxin to specific anti-digoxin antibody. Two of these inhibitors were purified by a combination of Amberlite XAD-2 adsorption chromatography and 3 steps of high-performance liquid chromatography. Reverse phase, high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectrometry identified these substances as linoleic (18:2) and oleic acids (18:1). A significant increase in the ouabain-displacing activity was observed in hog plasma during saline infusion. The maximal level reached was approximately 10 times higher than that of the preinfusion plasma sample. The two unsaturated fatty acids contributed to approximately 52% of the total ouabain-displacing activity after 120 min of saline infusion. The increased fatty acid levels in volume-expanded plasma are sufficient for an extensive inhibition of Na+,K+-ATPase activity. These results strongly suggest that free unsaturated fatty acids in plasma regulate extracellular fluid volume in a pathological volume-expanded condition through modulation of Na+,K+-ATPase activity.

Animals↗
PubMed1985

Radiation therapy of rat brain tumor using misonidazole as hypoxic cell sensitizer.

Rat brain tumor was used as a model to evaluate radiation therapy with and without misonidazole. BD-IX rats were implanted intracerebrally with an ethylnitrosourea-induced glioma. Three series of experiments were performed, with radiation given 14 days after inoculation of the glioma clone. In each series, the following radiation doses were given: 500 rads once, 1,000 rads once; and 1,000 rads twice, every time with or without two different doses of misonidazole. Radiation therapy significantly prolonged survival when compared to the longevity of the control group. The dose of 1,000 rads given twice was highly effective and the life-span of tumor-bearing rats increased from 72% to 121%. Misonidazole plus irradiation negated the prolongation of survival, achieved with radiation therapy alone.

Animals↗
PubMed1985

Successful transplantation of soy bean agglutinin-fractionated, histoincompatible, maternal marrow in a patient with severe combined immunodeficiency and BCG infection.

A successful transplantation of soybean agglutinin (SBA) and sheep red blood cell (SRBC)-fractionated, maternal marrow in a patient with severe combined immunodeficiency (SCID) is reported. The engraftment of HLA-haplotype mismatched marrow cells was obtained without apparent graft versus host disease (GVHD). With immunological reconstitution the patient recovered from a BCG infection, which might have been caused by a BCG inoculation before his bone marrow transplantation.

Adult↗
PubMed1985

Induction of human interferon gamma in nylon-column nonadherent human lymphocyte cells by heat-treated poly I:poly C.

Human peripheral blood mononuclear leukocytes (PBML) were separated by Ficoll-hypaque gradient from human peripheral whole blood cells. The PBML were further separated by nylon-column. When nylon-column nonadherent cells (NNA cells) were induced by poly I:poly C which was prepared by heat-treatment, high levels of acid- and heat-labile interferon (IFN) were obtained. The IFN was not neutralized with human IFN-alpha or -beta anti-serum, but was completely neutralized with human IFN-gamma anti-serum, indicating that the IFN was human IFN-gamma.

Cell Adhesion↗
PubMed1985

Systemic cardiac output and distribution during high-frequency oscillation.

High-frequency oscillation (HFO) appears to be an alternate, less traumatic mode of ventilating surfactant-deficient patients, because conventional (mechanical) pressure-limited ventilation (CMV) compromises cardiac function at high mean airway pressures. We compared systemic cardiac output and its distribution during HFO and CMV in ten adult rabbits rendered surfactant deficient by repeated pulmonary saline lavage. Cardiac output and organ blood flow were measured using the radionucleotide-labeled microsphere technique during ventilation at a mean airway pressure of 15 cm H2O and an inspired oxygen concentration of 100%. Both cardiac output and organ perfusion were similar during both modes of ventilation.

Animals↗
PubMed1985

Palmitoyl-CoA elongation in brain microsomes: dependence on cytochrome b5 and NADH-cytochrome b5 reductase.

Experiments were performed to demonstrate the involvement of electron transport system in fatty acid elongation in rat brain microsomes. Mercuric chloride and p-chloromercuriphenylsulfonate, inhibitors on NADH-cytochrome b5 reductase, at 32 microM inhibited NADH-supported palmitoyl-CoA elongation to 30 and 60% of control activity, respectively, whereas NADPH-supported palmitoyl-CoA elongation was unaffected by these mercurials. An antibody to rat liver NADH-cytochrome b5 reductase inhibited brain microsomal NADH-cytochrome b5 reductase activity and NADH-dependent palmitoyl-CoA elongation. Treatment of brain microsomes with trypsin diminished the cytochrome b5 content; NADH- and NADPH-cytochrome c reductase activities were significantly decreased, but the decrease in NADH-cytochrome b5 reductase activity was relatively small. Whereas essentially no incorporation of malonyl-CoA into palmitoyl-CoA was observed with trypsin-treated microsomes, addition of detergent-solubilized cytochrome b5 resulted in a recovery of fatty acid elongation. These results indicate the presence of an electron transport system, NADH-NADH-cytochrome b5 reductase-cytochrome b5-fatty acid elongation, in brain microsomes.

4-Chloromercuribenzenesulfonate↗
PubMed1985

Physiological aspects of free-radical reactions.

Enzymes which catalyze the formation of free radicals in vitro will catalyze similar reactions in vivo. We believe that the formation of some kinds of free radicals has definite physiological meanings in metabolism. In this sense, the enzymes forming such free radicals are concluded to be in evolutionally advanced states. Elaborated structure and function of enzymes such as horseradish peroxidase and microsomal flavoproteins support the idea. Deleterious and side reactions caused by free radicals are assumed to be minimized in vivo by localizing the reactions, but this assumption should be verified by future studies.

Animals↗
PubMed1985

Determination by enzyme-linked immunosorbent assay (ELISA) of specific IgG antibody activities for diagnosis of farmer's lung disease.

The specific IgG antibodies to thermophilic actinomycetes in the sera from patients with farmer's lung disease were quantitated by an ELISA and the results thereof were compared with those obtained by the standard double immunodiffusion assay (Ouchterlony's method). All sera from patients with farmer's lung disease were precipitin positive to Thermoactinomyces vulgaris and/or Micropolyspora faeni by the Ouchterlony's method, and revealed significantly high levels of IgG antibody activities against these antigens by ELISA. We have found 18 precipitin-positive but asymptomatic subjects in a survey of the dairy farming population of the northern area of IWATE Prefecture. Their sera were precipitin positive to antigens related to the farmer's lung disease, however IgG antibody activities as determined by ELISA to these antigens was significantly lower in the group of asymptomatics than in the group of symptomatics. Precipitin negative dairy farming controls and normal controls living in the urban area revealed low antibody activities as determined by ELISA. From these studies, we concluded that the assay of specific IgG antibody activity to thermophilic actinomyces by ELISA is useful for the diagnosis and screening of farmer's lung disease.

Adult↗
PubMed1985

Dual mechanisms involved in the development of diverse biological activities of islet-activating protein, (pertussis toxin) as revealed by chemical modification of the toxin molecule.

Islet-activating protein (IAP) pertussis toxin is composed of an A-protomer and a B-oligomer. The B-oligomer binds to the mammalian cell surface via the constituent two dimers (D1 and D2). IAP displays several biological effects including lymphocytosis-promoting, histamine-sensitizing, adjuvant, vascular permeability increasing and mitogenic activities. These activities were markedly suppressed by acetamidination or reductive methylation of the lysine residues in the D2 molecule. The free amino groups of the lysine residues thus play an essential role in the binding of D2 to cells which is responsible for development of these biological activities. In sharp contrast, the islet-activating activity was not prevented by the same chemical modification of the IAP molecule. This activity results from ADP-ribosylation catalyzed by the A-protomer which is rendered accessible to the intramembrane substrate protein thanks to the B-oligomer binding to the cell surface. Free amino groups of the lysine residues played no role in this type of binding of the B-oligomer via D1. Thus, at least two mechanisms underly the diverse biological activities of pertussis toxin.

Adenosine Diphosphate Ribose↗