Search PubMed⌕ Search

Biomedical subjects

S Yamazaki

Publications and source records attributed to S Yamazaki.

At least 469 records · Page 26Linked to original sources
PubMed1987

Serological survey on dengue virus infection in Singapore.

A serological study on dengue infection conducted in Singapore during the period 1982 to 1984 showed that 54.4% of the healthy population between 6 months and over 50 years of age surveyed possessed no haemagglutination-inhibition antibody to dengue type 2 virus. Children below 10 years of age showed the lowest antibody prevalence and were at the greatest risk, with 96.6% susceptible to infection, whereas virtually all adults over 40 showed evidence of prior dengue infection. The geometric mean titre showed a rising trend indicating continuing acquisition of infection in the older age groups. The seropositivity rate of dengue infection of males was twice that of females. Among the 3 major ethnic groups, no significant difference in seropositivity was noted between the Malays and Indians, but the differences between Malays and Chinese and between Indians and Chinese were statistically significant. The study confirmed that the successful implementation of the nation-wide Aedes control programme is reducing endemic dengue virus transmission in the country.

Adolescent↗
PubMed1987

The effects of different vertical air temperatures on mental performance.

Mental performance (one-digit-addition test) under conditions of different vertical air temperatures (upper body vs. lower body) was studied in relation to psychological and physiological responses. Six healthy male subjects wearing light clothing were exposed to different vertical air temperatures for 105 min. The lower part of the body was exposed to an air temperature of 30 degrees C in all cases; the upper part of the body was exposed to temperatures of 15 degrees C, 20 degrees C, 30 degrees C and 35 degrees C. The performance in the one-digit-addition test decreased with increased upper air temperature, and upper air temperatures higher or lower than 25 degrees C resulted in increased discomfort. There was little difference between performance at the onset (5 min after exposure) and conclusion (90 min after exposure) at 15 degrees C and 20 degrees C upper air temperatures (UAT). The performance at 90 min, however, declined in comparison with the original value at 25 degrees C, 30 degrees C and 35 degrees C UAT. Mildly uncomfortable ambient conditions where upper air temperatures were cool and lower air temperatures were warm improved performance; however, at 35 degrees C, UAT performances worsened as the subjects felt uncomfortably hot.

Adult↗
PubMed1987

Characterization of E. coli-derived recombinant human interferon-beta as compared with fibroblast human interferon-beta.

Homogeneous E. coli-derived recombinant human interferon-beta (E. coli-rHuIFN-beta) was characterized in order to elucidate its physicochemical properties, as compared with those of fibroblast human interferon-beta (fibroblast HuIFN-beta). Purified E. coli-rHuIFN-beta and fibroblast HuIFN-beta exhibited a single band of Mr 19,000 and 23,000, respectively, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The primary structure of E. coli-rHuIFN-beta was identical to the prediction from the cDNA sequence. Furthermore, both the circular dichroism (CD) spectra and the 1H nuclear magnetic resonance (NMR) spectra of E. coli-rHuIFN-beta and fibroblast HuIFN-beta at pH 6.8 were closely similar to each other. On the other hand, on reverse-phase high-performance liquid chromatography (HPLC) using a C18 column, the retention time of E. coli-rHuIFN-beta was longer than that of fibroblast HuIFN-beta. Moreover, although the isoelectric point of E. coli-rHuIFN-beta was pH 8.9, purified fibroblast HuIFN-beta exhibited multiple isoelectric points, probably due to heterogeneity of the carbohydrate moiety. These results indicate that the E. coli-rHuIFN-beta polypeptide folds similarly to fibroblast HuIFN-beta, and the carbohydrate moiety of natural HuIFN-beta has little influence on higher-order structure but does influence the hydrophobic and the electrostatic properties of the molecule.

Amino Acid Sequence↗
PubMed1987

In vitro maintenance of terminal-differentiated state in hepatocytes entrapped within calcium alginate.

In cultured hepatocytes entrapped within Ca-alginate, liver-specific functions such as induction of tyrosine aminotransferase and serine dehydratase were stimulated by increasing the cell density. In contrast, a growth-related function such as induction of glucose-6-phosphate dehydrogenase was strongly stimulated by decreasing the cell density. This reciprocal regulation was mimicked by the addition of plasma membranes purified from adult rat liver to entrapment cultures at low cell density. Also, gluconeogenesis from lactate was stimulated by the addition of epinephrine (alpha,beta-agonist) with propranolol (beta-blocker). These results suggest that entrapped hepatocytes maintain not only terminal-differentiated state but also alpha-adrenergic response as shown in vivo.

Alginates↗
PubMed1987

Seroepidemiology of hepatitis A virus in Japan.

A seroepidemiologic study to detect class-specific antibody against hepatitis A virus (HAV) was made with 831 randomly collected sera (415 in 1973 and 416 in 1984) from healthy Japanese. Competitive-inhibition, IgG, IgA, and IgM anti-HAV enzyme-linked immunosorbent assays (ELISA) were used. Both collections showed a low prevalence of IgG anti-HAV in young age groups and it increased rapidly at middle age and plateued at greater than or equal to 94% prevalence in the older age groups. However, two age groups spanning ages 25-34 demonstrated statistically lower IgG anti-HAV age prevalences in 1984 vs 1973 (P less than 0.001), with an average 10-year prevalence shift. These data suggest that there has been no significant level of HAV infection to alter antibody prevalences in Japan from 1973 to 1984. The markedly decreased incidence of HAV infection in Japan has created a presently large and growing population of HAV susceptibles.

Adolescent↗
PubMed1987

Hydrops fetalis caused by intrauterine human parvovirus infection.

During a large outbreak of erythema infectiosum in 1987 in Toyama prefecture, Japan, a 32-year-old woman acquired a mild rash on her arms and legs at 18 weeks of gestation. At 26 weeks and 4 days of gestation, the fetus died by hydrops fetalis and pregnancy was terminated. Histological studies of the fetus revealed degeneration of erythroblastic cells in the liver and bone marrow. Extensive extramedullary hematopoiesis and hemosiderin deposits were observed in the liver. Antibody response to human parvovirus B19 virus was demonstrated in maternal sera by ELISA. Furthermore, dot hybridization with the molecularly cloned DNA probe revealed the presence of human parvovirus DNA sequence in the fetal liver, spleen, lung, kidney and placenta. This report describes the first case in Japan of hydrops fetalis caused by human parvovirus B19 infection.

Adult↗
PubMed1987

Four new hepatectomy procedures for resection of the right hepatic vein and preservation of the inferior right hepatic vein.

Among the accessory hepatic veins, the thickest one is the IRHV and is a significant vessel in 20 to 24 per cent of the patients. In these patients, if the right hepatic vein is totally resected, the right posteroinferior area can be preserved with the IRHV. Four types of hepatectomies n which the IRHV was preserved were proposed and three of the four procedures were performed upon five patients. In these five operations, the hepatectomies were successfully performed and blood losses were from 1,020 to 3,200 milliliters. These operative procedures, which have not been described before, could widen the indication of hepatectomy in patients with reduced liver function and tumor involving the right hepatic vein. In order to perform these operative procedures successfully, intraoperative sonography is indispensable.

Adult↗
PubMed1987

Immune status of the population to poliovirus infection in Singapore.

A seroepidemiological survey conducted after two decades of mass immunization against poliomyelitis in Singapore showed a high level of herd immunity in the population to all three types of human poliovirus. Neutralizing antibodies to poliovirus 1, 2 and 3 were detected in 93.9-96.7% of the population between 6 months and over 40 years old. Adults above 30 years of age had a relatively high level of susceptibility to poliovirus infection, with 10.2-12% in the over-30-year age group possessing no neutralizing antibody against poliovirus 1, 14.3% in the 40+ age group against poliovirus 2, and 14% in the 30-39-year age group against poliovirus 3. The geometric mean titres showed a general decline among the older age groups. There were no statistically significant differences in the immune status by sex and by ethnic groups (Chinese, Malays and Indians). The importance of maintaining a high coverage of immunization, monitoring the herd immunity of the population to identify high-risk groups, and advising adults travelling to the endemic areas to be immunized against poliomyelitis was stressed.

Adolescent↗