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Biomedical subjects

R Morikawa

Publications and source records attributed to R Morikawa.

10 recordsLinked to original sources
PubMed2005

Effect of ruminal administration of Escherichia coli wild type or a genetically modified strain with enhanced high nitrite reductase activity on methane emission and nitrate toxicity in nitrate-infused sheep.

The effects of two kinds of Escherichia coli (E. coli) strain, wild-type E. coli W3110 and E. coli nir-Ptac, which has enhanced NO(2) reduction activity, on oral CH(4) emission and NO(3) toxicity in NO(3)-treated sheep were assessed in a respiratory hood system in a 4 x 6 Youden square design. NO(3) (1.3 g NaNO(3)/kg(0.75) body weight) and/or E. coli strains were delivered into the rumen through a fistula as a single dose 30 min after the morning meal. Escherichia coli cells were inoculated for sheep to provide an initial E. coli cell density of optical density at 660 nm of 2, which corresponded to 2 x 10(10) cells/ml. The six treatments consisted of saline, E. coli W3110, E. coli nir-Ptac, NO(3), NO(3) plus E. coli W3110, and NO(3) plus E. coli nir-Ptac. CH(4) emission from sheep was reduced by the inoculation of E. coli W3110 or E. coli nir-Ptac by 6 % and 12 %, respectively. NO(3) markedly inhibited CH(4) emission from sheep. Compared with sheep given NO(3) alone, the inoculation of E. coli W3110 to NO(3)-infused sheep lessened ruminal and plasma toxic NO(2) accumulation and blood methaemoglobin production, while keeping ruminal methanogenesis low. Ruminal and plasma toxic NO(2) accumulation and blood methaemoglobin production in sheep were unaffected by the inoculation of E. coli nir-Ptac. These results suggest that ruminal methanogenesis may be reduced by the inoculation of E. coli W3110 or E. coli nir-Ptac. The inoculation of E. coli W3110 may abate NO(3) toxicity when NO(3) is used to inhibit CH(4) emission from ruminants.

Animals↗
PubMed2005

Effect of Escherichia coli wild type or its derivative with high nitrite reductase activity on in vitro ruminal methanogenesis and nitrate/nitrite reduction.

The effects of two kinds of Escherichia coli strains, wild-type E. coli W3110 or E. coli nir-Ptac, which has enhanced nitrite reduction activity, on in vitro CH4 production and nitrate and nitrite reduction in cultures of mixed ruminal microorganisms was investigated using continuous incubation systems. Escherichia coli nir-Ptac, a derivative of wild-type E. coli W3110, was constructed by replacing self promoter of nir BD operon encoding subunits of nitrite reductase in E. coli W3110 by tac promoter to make the expression of nir BD higher and constitutive. The nitrite reductase activity of E. coli nir-Ptac was approximately twice as high as E. coli W3110. The culture media consisted of 400 mL of strained ruminal fluid taken from two nonlactating Holstein cows receiving a basal diet of orchardgrass hay at maintenance level (55 g of DM/kg of BW0.75 daily), and 400 mL of autoclaved artificial saliva. Treatments were arranged in two separate 3 x 3 factorials consisting of nitrate (NaNO3; 0, 5, or 10 mM) without E. coli or inoculated with E. coli W3110 or E. coli nir-Ptac, or nitrite (NaNO2; 0, 1 or 2 mM) without E. coli or inoculated with E. coli W3110 or E. coli nir-Ptac. The control culture contained no chemical or microbial additives. Escherichia coli cells were inoculated into in vitro mixed ruminal cultures at approximately 2 x 10(8) to 10(9) cells/mL. Methane production by ruminal microorganisms was decreased markedly (P < 0.001) by the addition of nitrate and nitrite, and by the inoculation of cultures with E. coli W3110 or E. coli nir-Ptac (P < 0.01). With mixed nitrite-containing cultures, E. coli nir-Ptac inhibited (P < 0.001) in vitro nitrite accumulation and CH4 production more than E. coli W3110, which may be due to the tac promoter-enhanced nitrite reductase activity of E. coli nir-Ptac accelerating electrons to be consumed for nitrite reduction rather than CH4 biosynthesis. In conclusion, anaerobic cultures of E. coli W3110 or E. coli nir-Ptac may decrease CH4 production in the rumen. The inoculation of E. coli W3110 or, especially, E. coli nir-Ptac to mixed ruminal microorganisms may decrease nitrite toxicity when ruminants consume high-nitrate-containing forages and when nitrite is applied to abate ruminal CH4 production.

Animals↗
PubMed2005

Effects of yeast culture and galacto-oligosaccharides on ruminal fermentation in holstein cows.

Four nonlactating, ruminally cannulated Holstein cows were used in a 4 x 4 Latin square design, balanced for residual effects, to evaluate the effects of supplementing dairy cow diets with yeast culture (Trichosporon sericeum; YC), galacto-oligosaccharides (GOS), or the mixture of YC and GOS on ruminal fermentation, microbial N supply, in situ degradation, and energy and nitrogen metabolism. Treatments were arranged in a 2 x 2 factorial as follows: 1) basal diet, 2) basal diet plus 10 g/d YC, 3) basal diet plus 2% GOS, 4) basal diet plus a mixture of 10 g/d YC and 2% GOS. Nitrogen losses in urine were lower, and retained N was higher, for cows supplemented with a mixture of YC and GOS. Ruminal pH was lower in cows supplemented with GOS alone compared with other treatments. Total VFA concentration was higher in cows fed control and GOS-supplemented diets than in those fed YC containing diets. The molar proportion of propionate was higher, and the molar proportion of acetate was lower, in cows fed control diets. Microbial N supply was higher in cows fed control diets. There were no major positive effects of supplements observed in this study. However, supplementation of a mixture of YC and GOS had a tendency for synergistic effects on N metabolism and in situ degradation of a soluble fraction of oat straw DM and CP of concentrates compared with supplementation of YC or GOS alone.

Animal Feed↗
PubMed2005

Distribution of aquaporin-9 in the rat: an immunohistochemical study.

The aim of this study was to identify the distribution of aquaporin-9 by immunohistochemistry in rat tissues using specific antipeptide antiserum which we recently produced. Anti-aquaporin-9 antibody was raised in New Zealand white rabbits immunized with a conjugate of synthetic aquaporin-9 peptide with bovine serum albumin. Immunohistochemical analysis was performed by avidin-biotin complex method. Aquaporin-immunoreactivity was visualized in the anterior pituitary, central nervous system, retina, thyroid gland, gastrointestinal tract, liver lung, pancreas and testis. When using antiserum preincubated with synthetic peptides or rat hypothalamus homogenate, which contains aquaporin-9 peptide, no significant stain of the hypothalamus was detected. These findings suggest that aquaporin-9 is widely distributed and that the method used is valuable in studying the distribution of aquaporin-9 in rats.

Animals↗
PubMed2004

Comparison of new different assay systems for thyrotropin receptor antibodies with reference to thyroid-stimulating antibodies and thyroid stimulation-blocking antibodies in Graves' disease.

The aim of our study was to evaluate the diagnostic sensitivity of the new thyrotropin receptor antibody (TRAb) assays (Cosmic TRAb CT, ELISA and Yamasa DYNOtest TRAb). TRAb was positive in 43 of 44 (97.7%) untreated patients with Graves' disease by both TRAb CT and/or ELISA and NYNOtest TRAb. Thus the new TRAb assays were clearly more sensitive than the conventional assay (positivity: 85%). There was a strong positive correlation between the data obtained in TRAb CT and/or ELISA and those obtained in DYNOtest TRAb (r = 0.942, p < 0.0001). There was a significant correlation between the new TRAb and TSAb (r = 0.696, p < 0.0001). Although there was a significant correlation between the new TRAb and thyroid stimulation-blocking antibody (TSBAb), the correlation coefficient was low (r = 0.605, p < 0.0001). The increased sensitivity of the new TRAb assays for Graves' disease provides an advantage over conventional assay.

Autoantibodies↗
PubMed1990

Isolation of human colon carcinoma cells for resistance to a single interferon associated with cross-resistance to multiple recombinant interferons: alpha, beta, and gamma.

We established variants resistant to human interferon (IFN) from an IFN-sensitive human colon carcinoma cell line and delineated some of the mechanisms for resistance to IFN-mediated cytotoxicity. The parent KM12C cells were incubated for 2 months in medium containing recombinant human IFN-alpha hybrid BBDD (r-IFN-alpha) or recombinant human IFN-gamma (r-IFN-gamma). Surviving variants were designated KM12 alpha R and KM12 gamma R, respectively. KM12 alpha R cells were cross-resistant to the cytostatic and cytolytic effects of r-IFN-alpha, r-IFN-beta, and r-IFN-gamma, whereas KM12 gamma R cells were resistant only to the effects of r-IFN-gamma. The parent and variant cell lines had similar in vitro growth rates and similar tumorigenicity in male BALB/c nude mice, but the mechanisms for resistance to IFNs differed in the two variant lines. The resistance of the cross-resistant KM12 alpha R cell line was not attributable to the loss of specific receptors, because our analyses demonstrated the presence of receptors for IFN-gamma, whereas the KM12 gamma R line lacked specific receptors for IFN-gamma. Northern blot analyses revealed that messenger RNA (mRNA) from the proto-oncogene c-myc was equally expressed in the IFN-sensitive and IFN-resistant cell lines and that treatment with r-IFN-gamma did not alter its expression. Treatment with r-IFN-gamma induced the expression of manganous superoxide dismutase mRNA in KM12C and KM12 alpha R cells, but not in KM12 gamma R cells, confirming that both KM12C and KM12 alpha R cells, but not KM12 gamma R cells, have functional receptors for IFN-gamma.

Blotting, Northern↗