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Biomedical subjects

T Miyamura

Publications and source records attributed to T Miyamura.

At least 127 records · Page 7Linked to original sources
PubMed1995

[Effect of vitamin D receptor gene polymorphism and lifestyle on bone mineral density and bone mineral density decrement rate].

The effects of genetic and environmental factors on bone mineral density (BMD) were investigated in 108 healthy Japanese women. Of the 108 subjects, BMD (from the second to forth lumbar vertebrae) was measured in 1992 in 103, in 1993 in 100, and in both years in 95 by dual energy X-ray absorptiometry. Vitamin D receptor (VDR) gene polymorphism in intron 8 was used as a genetic marker. Information on menstruation, health status, lifestyle, quantities of nutrient intake and frequencies of food intake was obtained by questionnaire. The frequency of allele B (825bp), whose polymerase chain reaction (PCR) products cannot be cut with BsmI, was 0.259 and the frequency of allele b (650bp), whose PCR products can be cut with BsmI, was 0.741. The subjects in our study obeyed the Hardy-Weinberg law. While the frequency of allele B was 0.448 in European whites as reported by Morrison et al, it was 0.259 in our Japanese subjects, suggesting a racial difference. Z score values (average value 0, standard deviation 1) increased in the order BB, Bb and bb. This result indicates that allele B is associated with the lower BMD in Japanese, as in European whites. The BMD decrement rate increased in the order bb, Bb and BB, indicating that VDR gene polymorphism may be a regulatory factor for losing BMD. Most of lifestyle variables, calcium intake and vitamin D intake were not correlated with BMD, but the food frequency score (which was defined as values weighted in each of three food categories obtained by factor analysis) was significantly correlated with BMD. Multiple regression analysis showed significant influences of years after menopause, the food frequency score and VDR genotype on BMD. VDR genotype and years after menopause influenced the BMD decrement rate significantly in multiple regression analysis. Neither a relationship between BMD and calcium intake nor between BMD and vitamin D intake by VDR genotype was found. These results suggest that the VDR gene is a genetic factor in BMD and the BMD decrement rate in Japanese.

Adult↗
PubMed1995

Proteolytic activity of NS3 serine proteinase of hepatitis C virus efficiently expressed in Escherichia coli.

The serine proteinase of hepatitis C virus (HCV) non-structural protein NS3 was efficiently expressed in an active form as a fused protein with oligohistidine in Escherichia coli. The recombinant fusion protein was purified to near homogeneity by affinity chromatography on a metal chelation column. Trans-cleavage activity of this protein was investigated by using the substrate NS5 protein expressed in insect cells. The purified serine proteinase trans-cleaved the partially purified NS5 protein. In contrast, the NS3 proteins with mutations at the proposed catalytic site, Ser1165 or His1083, lost the trans-cleavage activity. Analysis of the authentic enzyme and variants with site-directed mutations provides a useful tool for understanding the structure-function relationship of the NS3 serine proteinase. We then developed an in vivo trans-cleavage assay system by coexpression of the NS3 proteinase and the NS5 substrate in E coli, and examined the effect of known inhibitors of serine proteinase. Inhibition of its proteolytic activity by N-p-tosyl-L-lysine chloromethyl ketone (TLCK) was observed, but only at high concentrations. The in vitro and in vivo trans-cleavage assays for NS3 serine proteinase will facilitate efficient testing for inhibitors of the replication of HCV and specific treatment for hepatitis C.

Baculoviridae↗
PubMed1994

Processing of E1 and E2 glycoproteins of hepatitis C virus expressed in mammalian and insect cells.

Processing of the envelope glycoproteins (E1 and E2) of hepatitis C virus (HCV) was investigated by using cDNA clones covering the structural and part of the nonstructural (NS) protein regions. The cDNA clones expressed in mammalian and insect cells were immunoprecipitated by serum of a hepatitis C patient and by monoclonal and polyclonal antibodies raised against the recombinant proteins expressed in insect cells or Escherichia coli. The E2 protein expressed in both insect and mammalian cells was a glycoprotein of 60 kDa (gp60) and removal of the sugar residues by N-glycanase yielded 38- and 40-kDa proteins. Pulse-chase experiments revealed that efficient expression and processing of the envelope proteins required coexpression with the flanking core and NS2 proteins. Not only E1 and E2 proteins but also NS2 and NS3 proteins were coprecipitated by anti-E1 or anti-E2 monoclonal antibody in the cells infected with the recombinant baculovirus expressing structural and NS proteins (NS2 and NS3), while only the NS3 protein was precipitated by anti-NS3 antibody. The association of E1 and E2 proteins was not influenced by the presence of a reducing agent and was still observed in the cells coinfected with the deletion mutants lacking both internal and C-terminal hydrophobic regions of each protein. Furthermore, the truncated forms of the E1 and E2 proteins were secreted into the culture supernatant and some of them were still associated with each other.

Animals↗
PubMed1994

Clinical experience with Nikkiso centrifugal pumps for extracorporeal circulation.

A comparative study of a newly developed impeller-type centrifugal pump, Nikkiso HMS-15, was made to assess the effects on hemolysis, platelet function, and renal function for extracorporeal circulation (ECC) during open heart surgery. The Bio-pump (cone-type, Medtronic) and the roller pump were used as controls. The increase of serum hemoglobin level in the Nikkiso pump was significantly lower than that in the other pumps. The decrease of platelet counts was recognized after the initiation of ECC in the three pumps whereas the levels of platelet factor 4 and beta-thromboglobulin in the Nikkiso pump group increased by far less than in the other two groups. Moreover, renal function was better maintained in the Nikkiso pump group; in particular, a significantly higher urine output was recorded during ECC and for 1 h after the termination of ECC. The results of our clinical studies suggest that the Nikkiso centrifugal pump is suitable for ECC during open heart surgery.

Extracorporeal Circulation↗
PubMed1994

Characterization of HCV structural proteins expressed in various animal cells.

Hepatitis C virus (HCV) is a main causative agent for transfusion-associated and sporadic cases of non-A, non-B hepatitis throughout the world. HCV has a positive-strand RNA of about 9,400 nucleotides as its genome, whose organization is similar to those of animal pestiviruses or human flaviviruses. In spite of the lack of an effective replication system in tissue culture cells, genes coding for viral proteins of HCV have been identified. The putative nucleocapsid (p22) and envelope (gp35 and gp60) proteins have been expressed in cells by different vectors under various foreign promoters. Furthermore, a truncated core protein and association of envelope proteins with nonstructural proteins have also been observed. These synthesized viral proteins have been shown to be useful for diagnostic assays.

Animals↗
PubMed1994

Trans-suppression of gene expression by hepatitis C viral core protein.

We have demonstrated that the truncated hepatitis C (HCV) core protein with its C-terminal hydrophobic domains deleted is translocated to the nucleus of transfected cells (22). In this study, intact and truncated core proteins of HCV were transiently expressed in a human hepatoblastoma cell line, HepG2, and their effects on the expression of the chloramphenycol acethyl transferase (CAT) gene driven by viral and cellular promoters were examined. The intact core protein of 22 kDa which is localized in the cytoplasm of the transfected cells suppressed the expression in all of the promoters tested. They were promoters of the SV40 early region, the c-fos oncogene, the retinoblastoma susceptibility gene, the beta-interferon gene and the beta-actin gene. In contrast, the truncated HCV core protein located in the nucleus did not show such a suppressive activity. The HCV core protein appears to function not only as a viral structural protein but as a regulator of gene expression and it might act as a suppressive factor for the cellular gene expression.

Antibodies, Viral↗
PubMed1994

[Study on the association between risk factors for osteoporosis and bone mineral density].

The relationship between bone mineral density (BMD) and risk factors for osteoporosis was investigated on 146 females (23-68 years old) in Enzan city, Yamanashi prefecture. BMD was measured by DEXA (Dual Energy X-ray Absorptiometry) method. Information regarding menstruation, health status, life-style, quantities of nutrient intake and frequencies of food intake were obtained by questionnaire. Fitness level was determined by exercise test and daily energy expenditure by calorie-counter. The results were as follows; 1) No relationship between physical activities or daily energy consumption and BMD was found. 2) No relationship between calcium intake or vitamin D intake and BMD was found, but a significant and positive correlation coefficient between intake frequency of milk products and BMD was observed. 3) Significant influences of age, BMI, presence of lumbago and food frequency score on BMD were indicated by multiple regression analysis. Food frequency score were defined as values weighted in each of three food category, obtained by factor analysis. 4) Significant influences of height decrement rate per year and number of years postmenopausal on BMD reduction rate per year were indicated by multiple regression analysis. These results suggest that these significant factors are useful in indications of risk for osteoporosis.

Adult↗