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Biomedical subjects

M Tamura

Publications and source records attributed to M Tamura.

At least 955 records · Page 53Linked to original sources
PubMed1982

Calcium-binding proteins in bovine milk: calcium-binding properties and amino acid composition.

The Ca2+-binding properties and amino acid compositions of two calcium-binding proteins (mCaBP-3 and mCaBP-4) purified from bovine milk were studied. mCaBP-3 was identified as a Ca2+-bound type and mCaBP-4 as a Ca2+-free type by means of ion-exchange chromatography on a DEAE-Sephadex A-25 column. In polyacrylamide gel disc electrophoresis, both mCaBP-3 and mCaBP-4 had the same mobility of Rf = 0.73 and the addition of 5 mM CaCl2 to the electrode buffer decreased the mobility from Rf = 0.73 to Rf = 0.49. mCaBP-3 and mCaBP-4 consisted of 120 and 122 amino acid residues, respectively. The molecular weights were 13,758 and 13,967, respectively. The amino acid compositions of the two milk CaBPs very closely resembled each other. Both milk CaBPs were rich in aspartic acid, glutamic acid, leucine and lysine, but did not contain trimethylated lysine and amino sugar. An interesting feature is that each milk CaBP contained eight cysteine sulfone and three tryptophan residues per molecule. From these results, it is suggested that mCaBP-3 and mCaBP-4 are identical protein and that mCaBP-3 is formed from mCaBP-4 by means of a conformational change by binding of Ca2+. Thus, mCaBP-3 is a holoprotein and mCaBP-4 is an apoprotein. Furthermore, it is suggested that milk CaBP is different from calmodulin, troponin C and vitamin D-dependent calcium-binding protein.

Amino Acids↗
PubMed1982

[Pulmonary metastasis of the stomach cancer].

Despite the fact that the lungs have a plenty of blood and lymphatic supply, only 20-40% of pulmonary metastasis from the stomach cancer are found. Pulmonary metastases are most commonly described as well-circumscribed lesions complicated with hilar metastasis. However, the most important picture is that of diffuse lymphatic permeation, which may produce clinical and radiologic features of lymphangitis carcinomatosa showing a characteristic roentgenologic appearance, namely, a fine feathery interstitial streaking. Furthermore, pleuritis carcinomatosa is a common type of metastasis from the stomach cancer and often presents a difficult management problem. Instillation of cytotoxic or sclerosing agents into the pleural space can be effective in preventing recurrence.

Humans↗
PubMed1981

Horseradish peroxidase C.

Horseradish peroxidase C (HRP; ferric) reacts with H2O2 to form Compound I, with an equilibrium constant of about 10(14) M-1. Two-step reduction of Compound I to Compound II and further to the ferric enzyme occurs reversibly at Eo' values of 0.90 and 0.93 V (pH 7.0), respectively. The pH dependence of Eo' values for each one-electron step, ferrous leads to ferric leads to Compound II leads to Compound I indicates that presence of redox-linked ionization at pKa values of 7.3 in the ferrous state, 11.0 in the ferric and 8.6 in Compound II. Zinc-substituted HRP C is oxidized to its free-radical form at an Eo' value of 0.74 (pH 6.0) Comparison of oxidized zinc HRP C with Compound I shows that Compound I contains a porphyrin pi-cation radical. The flash photolysis study on the NO-ferric HRP C complex clearly indicates that the iron is pentacoordinated in HRP C while it is hexacoordinated in metmyoglobin. From the kinetic analysis of the acid-alkaline conversion of HRP C, the second-order rate constants of the reactions with H+ and HO- are estimated to be 1.5 X 10(10) and 6.7 X 10(4) M-1s-1, respectively. The latter rate constant greatly varies with the kind of hemoproteins. In the presence of HRP C and O2, indole-3-acetate is oxidized to its hydroperoxide form, which reacts effectively with HRP C to form Compound I and further converts Compound I to a verdohemoprotein.

Electron Transport↗
PubMed1981

Age-dependent decay of cytochrome b5 and cytochrome b5 reductase in human erythrocytes.

Age-dependent decrease in cytochrome b5 was observed in erythrocytes from both a normal person and a patient with hereditary methaemoglobinaemia without neurological symptoms. With aging, concentrations of cytochrome b5 in erythrocytes from the patient were almost the same as those in the control. Age-dependent decrease in cytochrome b5 reductase activity in the control erythrocytes was also shown; however, the reductase activity was very low in erythrocytes from the patient over the whole age range. Our studies show that methaemoglobin content of erythrocytes seems to be dependent on the content of cytochrome b5 in the cells, both in the control subject and in the patient.

Cytochrome Reductases↗
PubMed1981

Primary leptomeningeal melanoma with epipharyngeal invasion.

A case of primary leptomeningeal malignant melanoma in a 45-year-old woman is reported. The tumour was located at the basal aspect of the brain with a larger aggregation in the left parasellar and cerebello-pontine angle regions. The tumour showed not only spinal meningeal dissemination but also infiltration into the petrous bone and along the trigeminal nerve till it reached the submucosal tissue of epipharynx. There are a few reported cases of primary leptomeningeal melanoma which invaded areas outside the central nervous system.

Arachnoid↗
PubMed1981

A case report of venous aneurysm of the neck vein.

We treated a 37 year old woman with venous aneurysm along left side of the neck. In the beginning, she was asymptomatic and with increase in size of the venous aneurysm she experienced severe pain. Pathohistological examinations revealed a destructive change of the venous wall and thrombosis. Therefore, in cases of venous aneurysm along the neck, such aneurysm should probably be treated surgically to prevent the occurrence of pulmonary embolism.

Adult↗
PubMed1981

The influence of the Haldane effect on alveolar CO2 tension equilibrated with mixed venous blood in man.

When blood in the pulmonary capillary is oxygenated in hypercapnic air, PCO2 in the red cell has been thought to exceed alveolar PCO2 due to the Haldane effect, inducing outward CO2 diffusion. As long as the inward CO2 diffusion and, consequently, HCO3- formation are prevented in the red cell, the CO2 gain in plasma is reduced down to the level predicted from a CO2 dissociation curve of separated plasma. Therefore, if the direction of the CO2 diffusion is not reversed during the contact time, the virtual venous PCO2 (PEq), where the CO2 loss due to the Haldane effect is balanced with the gain due to the venoalveolar PCO2 gradient, becomes higher than the oxygenated venous PCO2 in proportion to the CO2 difference between the true and separated plasma. In order to verify the validity of the above assumption, the PEq value was measured in normo- and hypercapnia by using the Defares' extrapolation method in six normal subjects. The results obtained revealed that the PEq estimated in hypercapnia was obviously higher than that in normocapnia. The above difference was significantly greater in normoxia than in hypoxia. Furthermore, it agreed fairly well with the theoretical difference presumed by taking the difference in CO2 content between separated and true plasma and the R. Q. effect on the alveolar gas volume into account, suggesting that the inward CO2 diffusion following the oxygenation reaction could be disregarded in normoxic hypercapnia.

Adult↗
PubMed1981

Relationship between venoarterial CO2 content difference and venoalveolar PCO2 difference in acute hypercapnia in dogs.

When mixed venous blood is oxygenated in alveolar air with higher PCO2, the PCO2 within the red cell is though to exceed the alveolar PCO2 due to the Haldane effect and to block the inward CO2 diffusion. If the direction of the CO2 diffusion is not reversed during the contact time, the HCO2-gain in the plasma will not exceed the amount estimated from venoalveolar PCO2 difference by using a CO2 dissociation curve of separated plasma. In order to clarify the validity of the above thought, the venoarterial CO2 content difference was measured by using a van Slyke apparatus and a PCO2 electrode at various alveolar PCO2 levels in rebreathing dogs. The HCO3-rise in the whole blood was obviously reduced when acute hypercapnia was administered in both normoxia and hyperoxia. Quantitatively, the decrease of CO2 content under hypercapnia corresponded to the difference in CO2 content between the true and separated plasma. The reduction, however, was slightly stronger in normoxia than in hyperoxia with alveolar PO2 of 300 to 420 mmHg. These data seem to support the following explanation: When venous blood was oxygenated in normoxic air with PCO2 higher than true venous, the inward CO2 diffusion was inhibited by the Haldane effect and the reversed diffusion after the oxygenation could also be disregarded during the contact time. Because the oxygenation was accelerated in hyperoxia and the direction of the CO2 diffusion was reversed earlier than in normoxia, the plasma CO2 content became higher in hyperoxia than in normoxia.

Animals↗