Biomedical subjects

Masakazu Murata

Publications and source records attributed to Masakazu Murata.

6 recordsLinked to original sources

PubMed2005

Inhibitory effect of porphyran, prepared from dried "Nori", on contact hypersensitivity in mice.

Porphyran is a major component of the red algae, Porphyra tenera and P. yezoensis, which are processed into a sheet type of dried food, "Nori". Porphyran has been reported to activate murine macrophages by in vitro and i.p. injection studies. The contact hypersensitivity (CHS) reaction in mice is commonly used as a model to evaluate the anti-allergic activity of food and food components. We therefore studied the effect of porphyran on the CHS reaction in Balb/c mice to evaluate anti-allergic activity of porphyran. We found that an oral administration of porphyran (2% in drinking water) suppressed the CHS reaction (ear edema) induced by 2,4,6-trinitrochlorobenzene. We also found that porphyran suppressed the serum level of IgE and the production of interferon-gamma (IFN-gamma) in the challenged ear lobe. We conclude from these results that the CHS reaction was suppressed by oral porphyran due to the decreased serum level of IgE and the production of IFN-gamma in the challenged ear lobe.

Animals↗

PubMed2004

Fish protein stimulated the fibrinolysis in rats.

OBJECTIVE: We hypothesized that fish protein affects blood coagulation and/or fibrinolysis, and compared the activity and amounts of factors involved in blood coagulation and fibrinolysis in rats fed the fish protein, which was treated to remove water-soluble and ethanol-soluble elements, from sardine (sardine protein). METHODS: In the first experiment, rats were fed for 21 days an AIN-93G-based control diet, and diets in which the casein of the control diet was exchanged for sardine protein at 5, 10 and 20% levels. In the second experiment, rats were fed an AIN-93G control diet and diets containing 5% fish oil, 10% sardine protein or both (5% fish oil + 10% sardine protein) for 21 days. At the end of the experiments, blood coagulation time, hemostatic parameters and fibrinolysis parameters were measured. RESULTS: The activated partial thromboplastin time (APTT), which is an assay for blood coagulation time in the intrinsic blood coagulation pathway, of rats fed the 20% sardine protein diet was significantly prolonged compared to that of rats fed the control diet. The prolonged APTT by dietary sardine protein was due to a significant decrease of the activities of plasma blood coagulation factors VIII, IX, XI and XII. On the other hand, dietary sardine protein significantly increased the activity of tissue-type plasminogen activator, and the amount of plasma plasmin-alpha(2)-plasmin inhibitor complex, which are markers of activated plasmin. Moreover, we observed that the 20% sardine protein diet increased the amount of plasma D-dimer, which is a degraded product of the fibrin polymer by plasmin. In the second experiment, the APTT and PT of rats fed the F diet were prolonged compared to those of rats fed the control diet, however the concentration and amount of fibrinolytic parameters in the plasma were almost the same as those of rats fed the control diet. In contrast, the F+S diet not only prolonged APTT and PT, but also increased the concentration and amount of fibrinolytic parameters in plasma. CONCLUSIONS: We consider that the beneficial effects to health and amelioration of cardiovascular and cerebrovascular diseases by fish consumption are caused by a combination of the suppressing effect on blood coagulation of n-3 polyunsaturated fatty acids and the promoting effect on fibrinolysis of fish protein.

Animals↗

PubMed2004

Warfarin reduces the incidence of osteonecrosis of the femoral head in spontaneously hypertensive rats.

In this study, we investigated the effects of warfarin potassium on the incidence of the femoral head osteonecrosis in spontaneously hypertensive rats (SHR). Twenty-four SHRs were divided into two equal groups, one given normal water (water group) and another provided with water containing warfarin (warfarin group). We compared the two groups histologically and observed the incidence of osteonecrosis. We also studied 17 Wistar Kyoto rats (WKY) to compare with SHR. Coagulation time, platelet count, and protein C activity were measured. Immunohistochemistry was also performed using endothelial nitric oxide synthetase (eNOS) antibody to investigate the function of endothelial cells. The incidence of osteonecrosis was significantly less in the warfarin group (10.5%) than in the water group (52.6%). Coagulation time was significantly longer in the warfarin group than the water group. Platelet count and protein C activity were not statistically different between the warfarin group and the water group. Results of immunohistochemistry revealed that endothelial cells in the femoral head were positive for eNOS in WKY but not in SHR. Our results indicated that warfarin reduced the incidence of femoral head necrosis in SHR.

Animals↗

PubMed2003

Docosahexaenoic acid suppresses nitric oxide production and inducible nitric oxide synthase expression in interferon-gamma plus lipopolysaccharide-stimulated murine macrophages by inhibiting the oxidative stress.

N-3 polyunsaturated fatty acids (PUFAs) are known to have anti-inflammatory effects. Excess production of nitric oxide (NO) is associated with inflammation. Therefore, we examined the effects of PUFAs on NO production and inducible NO synthase (iNOS) expression by stimulated murine macrophages. One typical n-3 PUFA docosahexaenoic acid (DHA) strongly inhibited NO production and iNOS expression in RAW264 macrophages and mouse peritoneal macrophages in a dose-dependent manner. This inhibition was accompanied by inhibiting the oxidative stress-sensitive transcription factor nuclear factor (NF)-kappaB activation. In stimulated macrophages, intracellular peroxides level was enhanced, but pretreatment of DHA dose-dependently inhibited this enhancement. These results suggest that DHA has an antioxidative effect based on the inhibition of the accumulation of intracellular peroxides, and this inhibition caused the suppression of the activation of NF-kappaB, resulting in the inhibition of NO production and iNOS expression. On the other hand, DHA treatment enhanced the level of intracellular glutathione (GSH), and this enhancement is thought to mediate the activity of DHA because lowering the GSH level by inhibiting GSH biosynthesis reversed the DHA-induced suppression of NO production, NF-kappaB activation, and the accumulation of intracellular peroxides. Our results demonstrate that DHA inhibits NO production in macrophages and this inhibition is, in part, mediated by upregulation of GSH.

Animals↗

PubMed2003

Blood coagulation and fibrinolysis of rats fed fish oil: reduced coagulation factors especially involved in intrinsic pathway and increased activity of plasminogen activator inhibitor.

Differences in the coagulation and fibrinolytic system of rats fed a fish oil based diet (fish oil diet) and fed a soybean oil based diet (control diet) were determined. Concentrations of plasma lipids were depressed in rats fed the fish oil diet. Prothrombin time (PT) and activated partial thromboplastin time (APTT) of rats fed the fish oil diet were longer than for the rats fed the control diet. Fish oil intake lowered the activities of most of the blood coagulation factors, and strongly depressed the factors involved in the intrinsic pathway. Fish oil also affected the fibrinolysis of rats. Plasminogen activator inhibitor (PAI) activity was elevated in rats fed the fish oil diet. In this study, both blood coagulation and fibrinolysis were down-regulated by feeding the fish oil diet.

Animals↗

PubMed2002

Dietary fish oil and Undaria pinnatifida (wakame) synergistically decrease rat serum and liver triacylglycerol.

Japanese eating habits are characterized by the consumption of various food materials such as cereals, vegetables, fish, shellfish, marine algae and meat. Therefore, properties of functional substances in food materials may be enhanced or lessened by the combination of various food materials. In the present study, we examined how the combination of wakame and fish containing polyunsaturated fatty acids, which are typical Japanese food materials, affected rat lipid metabolism. Rats were fed one of four diets [control diet (C), AIN-76 diet with 5 g/100 g rapeseed oil; wakame diet (W) containing 19.1 g/100 g Undaria pinnatifida (wakame) dried powder in the C diet; fish oil diet (FO), AIN-76 diet with 4.1 g/100 g fish oil; wakame-fish oil diet (W + FO), the FO diet containing 19.1 g/100 g dried wakame powder] for 4 wk. We measured the concentration of lipids in serum and liver and hepatic activities of enzymes involved in fatty acid metabolism. The W diet, FO diet and W + FO diet significantly reduced the concentration of triacylglycerols in the serum and liver compared with the C diet. This decrease in the concentration of hepatic triacylglycerol was greatest in rats fed the W + FO diet. The activity of glucose-6-phosphate dehydrogenase, which is involved in fatty acid synthesis in the liver, of rats fed the W, FO and W + FO diets was lower than that in rats fed the C diet. However, the activities of malic enzyme and fatty acid synthetase did not differ among the four groups. In contrast, the W diet and W + FO diet increased the serum concentration of beta-hydroxybutyrate. Further, the activity of 3-hydroxyacyl-CoA dehydrogenase, which is involved in fatty acid beta-oxidation in the liver, was greater in rats fed the W diet (42%), the FO diet (154%) and the W + FO diet (381%) than in those fed the C diet. Because the decrease in the concentration of triacylglycerol in the liver was greatest when rats were fed wakame and fish oil at the same time (W + FO diet), we conclude that there was a synergistic process affecting fatty acid beta-oxidation in the liver. These results suggest that the simultaneous consumption of fish (fish oil) and wakame decreases the concentration of triacylglycerol in the serum and liver.

Analysis of Variance↗