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Biomedical subjects

N Chen

Publications and source records attributed to N Chen.

At least 217 records · Page 12Linked to original sources
PubMed1989

[Multifactorial stepwise regression analysis of videofluoroscopic measurement and speech function after the repair of cleft palates].

The relationship between phonating and the multiview videofluoroscopic measurement of velopharyngeal range was studied by multifactorial stepwise regression analysis using an electronic computer. The results showed: (1) The degree of velopharyngeal closure is the most important factor during phonating; (2) There are close correlations between the degree of clearness of speech, the raising angle of soft palate and the contracture ability of lateral pharyngeal walls; (3) There are close relations between the length of soft palate and the degree of velopharyngeal closure; (4) There are also close correlations between the elongation of soft palate, the raising angle of soft palate, the contracture ability of lateral pharyngeal walls and the degree of velopharyngeal closure during phonating.

Adolescent↗
PubMed1988

Changes to the integral membrane protein composition of mouse liver peroxisomes in response to the peroxisome proliferators clofibrate, Wy-14,643 and di(2-ethyl-hexyl)phthalate.

Peroxisomes were purified from livers of control mice and from mice treated with three agents which induce proliferation of hepatic peroxisomes - namely two structurally unrelated hypolipidemic drugs, clofibrate (ethyl-alpha-p-chlorophenoxyisobutyrate) and Wy-14,643 (4-chloro-6[2,3-xylidino)-2-pyrimidinylthio]acetic acid), and a plasticizer, DEHP (di-(2-ethylhexyl)phthalate). Membranes were isolated from these purified peroxisomes and analysed by SDS-polyacrylamide gel electrophoresis. All membranes which were tested, displayed two predominant integral membrane proteins of apparent molecular weights of 68 kDa and 70 kDa respectively, as well as a number of minor components. Treatment of animals with clofibrate, Wy-14,643 and DEHP was observed to result in each case in an increased proportion of the 70 kDa protein in the peroxisomal membranes. These treatments also resulted in increased peroxisomal fatty acid oxidation in livers and an increase in the proportion of catalase activity in the cytosolic fraction of liver cells. These results have been discussed in relation to alterations in the molecular composition of the membranes, the mechanisms of peroxisome proliferation and the inducibility of peroxisomal membrane proteins.

Animals↗
PubMed1987

Fast atom bombardment and collisional activation mass spectrometry in the structural analysis of steroidal oligoglycosides.

Fast atom bombardment (FAB) followed by collisional activation (CA) mass spectrometry was used for structural analysis of steroidal oligoglycosides, containing two to four sugar units. In the molecular ion region of the FAB mass spectra of these underivatized natural products, intense protonated molecular ions were observed. The collisional activation spectra of these mass selected ions yield more sequence information than FAB mass spectra and are not contaminated with interfering peaks originating from impurities or matrix.

Diosgenin↗
PubMed1986

Census and survey of wild black-crested gibbons (Hylobates concolor concolor) in Yunnan Province, People's Republic of China.

Black-crested gibbons (Hylobates concolor concolor) inhabit the subtropical forests of Southern China and Northern Vietnam, and have never previously been the subject of any systematic behavioral or ecological study. This report presents the findings of a three-month census and survey of black-crested gibbons in the Wuliang and Ailao Mountain Game Reserves in Yunnan province, China. The censusing methods used here were similar to those techniques used during other census studies of gibbons. The sites visited were subtropical broadleaf evergreen forests, with trees belonging to the families Fagaceae, Theaceae, Magnoliaceae, Lauraceae and Elaeocarpaceae. A total of 23-25 groups of black-crested gibbons were documented from 4 sites visited, and a group density estimate from all sites averaged 0.82 groups/km2. These gibbons were found to be polygynous with an average family group size of 7-8 animals, comprising 1 adult male, 1-4 adult females and numerous offspring of various ages. Some of the ecological and evolutionary implications of these findings are also presented.

Animals↗
PubMed1984

Relationship between the plasma insulin response to oral glucose and insulin-stimulated glucose utilization in normal subjects.

The relationship between in vivo insulin-stimulated glucose utilization (euglycemic clamp technique) and various estimates of the plasma insulin response to oral glucose was defined in 62 subjects with normal glucose tolerance. Both the incremental insulin increase above fasting (r = 0.61) and the total integrated insulin response (r = 0.65) were highly correlated (P less than 0.001) with in vivo insulin action, and the relationship between total insulin response and insulin action remained significant (r = 0.61, P less than 0.001) when corrected for variations in total glucose response, age, and obesity. In a subset of these subjects (N = 27) we were also able to assess state of habitual physical activity by estimating maximal oxygen consumption during bicycle ergometry. A significant correlation also existed between insulin action and response in these subjects (r = 0.67, P less than 0.001), which remained significant (r = 0.65) when differences in total glucose response, obesity, age, and maximal oxygen consumption were taken into account. These data demonstrate that there is a significant correlation between insulin response and insulin action in normal individuals that can account for approximately one-third of the total variance in insulin action seen in subjects with normal glucose tolerance. Thus, determination of plasma insulin levels after an oral glucose challenge can only provide a qualitative estimate of insulin-stimulated glucose utilization.

Adult↗
PubMed1983

The primary hamster kidney cell rabies vaccine: adaptation of viral strain, production of vaccine, and pre- and postexposure treatment.

The hamster kidney cell rabies vaccine was investigated as a substitute for classical nervous tissue rabies vaccine. The Beijing strain of fixed rabies virus was adapted to primary hamster kidney cells (PHKCs), and four types of rabies vaccine (plain, adjuvant, concentrated, and concentrated adjuvant vaccines) were developed for human use. The potencies of the vaccines met the requirements of the World Health Organization, and these vaccines elicited rather satisfactory antibody responses in volunteers. The postexposure use of vaccine was evaluated in 301 individuals, 97 of whom had been bitten by proven rabid animals. None of the individuals contracted rabies during the observation period. After several years of field trials with both pre- and postexposure vaccines, the evidence indicates that the PHKC rabies vaccines are effective and safe for human use.

Animals↗
PubMed1980

Gravity and land plant evolution: experimental induction of lignification by simulated hypergravity and water stress.

The ability to lignify cell walls has long been associated with the upright condition and sometimes massive body of the land plant, and gravitational regulation of lignification has been demonstrated by clinostat/centrifuge techniques. Previous centrifuge experiments were conducted using plants in the early stages of growth, hence already programmed for immediate lignification. Elodea, an aquatic Angiosperm long believed to be incapable of lignification synthesizes lignin or lignin-like phenolics during 6 days incubation at 80 g . Yields in some cases exceeded stationary controls by as much as 300%. Supporting data were obtained using bean cotyledons. Exposure to 80 g induced lignification in extra-vascular tissue along with vascular lignin deposits. The loss of a buoyant medium also deprived early land plants of unlimited water: the lignin content in cucumber seedlings grown in water is reduced 50% or more relative to pot grown plants but water stress elevates lignin content as much as 100%. This suggests that the water status of the land environment may have provided a "backup" or "reinforcement" signal for an adaptive axial support system.

Biological Evolution↗
PubMed1980

A cytogenetic study of 1000 spontaneous abortions.

Cytogenetic analysis of 1000 spontaneous abortions showed 463 to have an abnormal chromosome constitution. The proportion of chromosome abnormalities varied with the gestational age of the abortus and the type of tissue cultured but was not significantly different among the five racial groups represented in the study population. It was suggested that differences in the rate of chromosome abnormalities among cytogenetic studies of spontaneous abortions were the result of methodological differences in sample selection rather than real biological variation among study populations. The only factor found to be unequivocally associated with the aetiology of chromosome abnormalities in spontaneous abortions was increasing maternal age in trisomies.

Abortion, Spontaneous↗
PubMed1978

Gonorrhea card test: an agglutination test for uncomplicated gonorrhea.

An antigen extracted and purified from Neisseria gonorrhoeae B370, type 4, was employed to sensitize charcoal particles for use in an agglutination assay of human sera for antibodies that indicate active gonorrheal infection. The screening card test is more sensitive than the fluorescent gonorrheal test-heated (FGT-H), especially in men. A simple one-step absorption improved the specificity without reducing the sensitivity of the test.

Agglutination Tests↗
PubMedDate not supplied

The retention behaviour of conjugated bile acids in reversed phase high performance liquid chromatography.

The retention behaviour of conjugated bile acids has been studied in a reversed phase high performance liquid chromatographic (RP-HPLC) system by using the mixture of methanol and aqueous phosphate buffer as the mobile phase. The retentions of the conjugates in RP-HPLC have been found to be mainly controlled by the glycine and taurine groups. The selectivity between five different glycine and taurine conjugated bile acids is a constant in RP-HPLC. This selectivity has been used for peak identification in the practical separation of conjugated bile acids.

Bile↗
PubMedDate not supplied

Free-solution capillary electrophoretic separation of small hydrophilic peptides.

Small hydrophilic peptides differing in only one glycine amino acid group have been successfully separated by free-solution capillary electrophoresis (FSCE) using phosphate buffer at acid pH. The effects of column temperature and operating current on the migration times of these small peptides have been investigated. The results from FSCE have been compared with those from reversed phase high performance liquid chromatography.

Chromatography, High Pressure Liquid↗