Search PubMed⌕ Search

Biomedical subjects

M Yamamura

Publications and source records attributed to M Yamamura.

At least 271 records · Page 15Linked to original sources
PubMed1984

Neuraminidase activity in human peripheral lymphocytes: its increase in chronic active liver disease.

The activity of neuraminidase (sialidase) in peripheral white blood cells was measured by a fluorometric method using 4-MU NANA as a substrate. The activity in mononuclear cells, which was predominantly lymphocytes, was 2.5 times higher than that in polymorphonuclear cells (neutrophils). The former's activity was directly proportional to the number of the cells, but that of the latter was found to be suppressed by an increasing number of cells. Thus, the increased number of PMN contaminated in MNC fraction somewhat obscured neuraminidase activity affecting suppressively . The enzyme activity in MNC of 25 control subjects (15 males and 10 females) was 254 +/- 73 pmoles per hour per 10(6) cells and there was no difference between the values in males and females (233 +/- 59 vs. 284 +/- 81). The activity in 20 patients with chronic active liver disease was significantly higher than that in controls (551 +/- 135, p less than 0.01). The amount of sialic acid in MNC, which was 1.4 times more than that in PMN, revealed a tendency for a positive correlation between neuraminidase activity. A new finding of the increase of lymphocyte neuraminidase activity was introduced and its pathological significance particularly in liver disease was discussed.

Chronic Disease↗
PubMed1984

Isolation and characterization of metallothionein from the tortoise Clemmys mutica.

A relatively high concentration of metallothionein was present in the liver of the control mature tortoise Clemmys mutica. The administrations of cadmium and copper to Clemmys mutica increased the metals in the liver with concomitant decrease of zinc, which was due to substitution of zinc in the native metallothionein with cadmium and copper. The Clemmys metallothionein was a mixture of three isoproteins which were abundant in half-cystine (34.2-34.6 mol%) and lysine (10.8-11.9 mol%), but lacked aromatic amino acids. One of the isoproteins, MT-I, contained one residue of histidine, which was an identical feature with frog and avian metallothioneins.

Amino Acids↗
PubMed1984

Effect of dietary unsaturated and saturated fats on azoxymethane-induced colon carcinogenesis in rats.

The effects of dietary unsaturated and saturated fats on chemically induced colon carcinogenesis were examined in male Donryu rats. The rats were fed two types of semipurified diets consisting of 5% linoleic acid or 4.7% stearic acid plus 0.3% essential fatty acid as dietary fats. The rats were treated with azoxymethane (7.4 mg/kg body weight) s.c. once a week for 11 weeks and sacrificed 15 weeks after the last injection of the carcinogen. The rats fed unsaturated fat diet demonstrated a significantly higher incidence of colon tumors [100%], more tumors per rat [2.68 +/- 1.60 (S.D.)], and greater malignant differentiation histologically than did those fed saturated fat diet [76%, 1.79 +/- 1.59, respectively]. Lipid analysis of colon tumors and colon mucosa showed that unsaturated fat diet altered the phosphatide fatty acyl composition of colon mucosa markedly and increased the content of arachidonic acid in the neutral lipid of colon tumors. The altered lipid composition of the mucosa may increase the sensitivity of the colon to the carcinogen, and the excess of arachidonic acid or its metabolites may be the primary agents of cocarcinogenesis of colon tumors. These findings suggest that dietary unsaturated fats have potent cocarcinogenic effects on colon carcinogenesis.

Animals↗
PubMed1983

Gel permeation, ion-exchange and reversed-phase columns for separation of metallothioneins by high-performance liquid chromatography-atomic absorption spectrophotometry.

Metallothioneins were separated on three kinds of HPLC column that differ in separation principle: gel permeation, ion exchange and reversed phase. Elution of the columns at neutral to weakly basic buffer conditions prevented dissociation of the metals, and the metals bound to metallothioneins were quantitatively eluted out. The metals in the eluate were continuously determined on an atomic absorption spectrophotometer by introducing the eluate directly to the nebulizer tube. Prerequisites for the on-line separation-detection system are discussed.

Animals↗
PubMed1983

A study on cadmium-induced nephropathy in rats pretreated with puromycin aminonucleoside.

Nephrotoxicity of cadmium (Cd) was investigated using puromycin aminonucleoside (AN)-pretreated rats. AN pretreatment was performed by iv injection of 100 mg AN/kg body wt 11 days before the initial Cd injection. Since massive proteinuria and focal glomerular deposits were recognized, glomerular permeability is considered to be increased in AN-pretreated rats. AN-pretreated and intact rats were injected sc with 3 mg Cd/kg body wt, 4 times a week. In non-pretreated rats, slight tubular vacuolation was seen after 1-week Cd exposure and severe vacuolation and coagulative necrosis of the tubules was observed after 2-week Cd exposure. On the other hand, AN pretreatment delayed the onset of vacuolation and necrosis for 1 week and made the lesion milder. After 1-week Cd exposure, a larger amount of Cd was excreted into the urine of AN-pretreated rats than of non-pretreated ones, whereas Cd accumulation in the kidney and liver was lower in AN-pretreated rats than in non-pretreated ones. Thereafter, no difference in Cd concentration was recognized between two groups. From these findings, it is suggested that in early stage of Cd administration, Cd was filtered through the glomerular basement membrane modified by AN pretreatment and that this filterable Cd did not have nephrotoxic effects in AN-pretreated rats.

Animals↗
PubMed1983

Effect of dietary cholesterol on azoxymethane-induced colon carcinogenesis in rats.

The effect of dietary cholesterol on azoxymethane (AOM)-induced colon carcinogenesis was evaluated with two different sets of experiments. Starting at 6 weeks of age, male Donryu rats were divided into four groups, and fed either control chow or one supplemented with 1% cholesterol, and with or without AOM (11 weekly s.c. injections at a dosage of 7.4 mg/kg body weight). The rats were sacrificed at 20 weeks after (first experiment) and at 15 weeks after (second experiment) the last injection of AOM. The AOM-treated groups in both experiments developed tumors in the colon and small intestine, whereas no tumors were seen in the AOM-untreated groups. An interesting observation was that cholesterol feeding significantly increased the number of colon tumors/rat and the number of animals with distant metastases to several organs. Tumor growth and invasiveness were also enhanced, but not significantly. Both bile acids and neutral sterols in the feces were markedly increased in the rats fed the 1% cholesterol supplement (2-3 fold and 5-6 fold, respectively). According to these results, it might be postulated that dietary cholesterol revealed potent promoting effects on AOM-induced colon carcinogenesis through the mechanism of increasing excretion of bile acids and neutral sterols in the gut.

Animals↗
PubMed1983

[Role of the spleen in tumor immunity--with special reference to anti-tumor immunity induced by solubilized and purified tumor-associated antigen].

The effects of post-operative immunization with purified tumor-associated antigen on the development of lung metastases following resection of the Lewis lung carcinoma (3LL) were studied. The soluble tumor-associated antigens were isolated from 3LL cells by detergent solubilization and purified by affinity chromatography on peanut agglutinin (PNA)-agarose. The immunization with subcutaneous injections of PNA-binding glycoproteins at early phase following resection of primary footpad tumors of 3LL resulted in a significant decrease in incidence and size of lung metastases. The delayed immunization, however, failed to suppress the development and growth of metastatic lung tumors after surgery. The suppression of postoperative development of lung metastases was found to depend on timing of immunization following local tumor resection. Splenectomy performed simultaneously with amputation of tumor-bearing leg was completely abolished the decrease in the development and growth of postoperative lung metastases in immunized-mice. Evidence of lymphoid system involvement in the control of metastatic tumor growth was also supported by the observation of in vivo tumor neutralization assay utilizing the spleen cells.

Animals↗
PubMed1982

The biological activity of alpha-1-antichymotrypsin: the change of chymotrypsin-inhibitory and immunoenhancing activities by heat treatment.

The relationship between chymotrypsin-inhibitory and immunoenhancing activity of alpha-1-antichymotrypsin was studied. alpha-1-Antichymotrypsin was treated at 50 degrees C, 55 degrees C or 60 degrees C for 15 min. It was found that antichymotryptic activity was reduced by half when alpha-1-antichymotrypsin was heated at 55 degrees C and was not detected at all when heating was carried out at 60 degrees C. alpha-1-Antichymotrypsin which was heated at 60 degrees C did not form a complex with chymotrypsin, but became a substrate for chymotrypsin. The effect of native and heated alpha-1-antichymotrypsin on antibody response was studied in mice. alpha-1-Antichymotrypsin increased the number of anti-sheep erythrocytes antibody producing cells even when it was heated at 60 degrees C. Circular dichroism and single radial immunodiffusion were used to detect conformational changes. Circular dichroism in the region of side chain absorption showed that the intensities of the spectra at 296, 284, and 265 nm decreased with a rise in temperature from 50 to 60 degrees C. In single radial immunodiffusion analysis, alpha-1-antichymotrypsin did not form a halo after being heated at 60 degrees C. In conclusion, when alpha-1-antichymotrypsin was heated at 60 degrees C, the immunoenhancing activity remained intact while the antichymotryptic activity was lost with the conformational change.

Adjuvants, Immunologic↗
PubMed1982

Biochemical and electron microscopic observations of cytotoxic effect of a fraction from hemolytic streptococcus on Ehrlich ascites carcinoma cells.

A protein fraction (60-F), obtained from cell-free extract of living hemolytic streptococcus, Su-strain, by 50-60% saturation with ammonium sulfate, inhibited the de novo synthesis of nucleic acids and proteins in Ehrlich ascites carcinoma (EAC) cells. 60-F released RNA but not DNA from EAC cells. This cytotoxic or cytolytic effect of 60-F was substantiated morphologically by scanning and transmission electron microscopic (SEM and TEM) observations, showing that 60-F induced cellular changes such as a loss of microvilli, bleb formation, cell deformity and partial gap of cell membrane in EAC cells. In addition, it was found that 60-F was more stable in RPMI-1640 medium supplemented with fetal calf serum than in other various media examined and was sensitive to temperature, pH changes and trypsin digestion.

Amino Acids↗
PubMed1982

Isolation, purification and identification of a serum DNA binding protein which increases in malignant diseases.

A DNA binding protein in human serum was purified and identified. This protein was isolated from pooled human serum by DEAE Sephadex column chromatography, DNA cellulose affinity column chromatography, Sephadex G-200 gel filtration and Sepharose 6B gel filtration. It was found that the purified protein consisted of two subunits, one with a molecular weight of 80,000 and the other 25,000, evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified protein was in fact IgM determined by physicochemical and immunochemical characteristics.

Carrier Proteins↗