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Biomedical subjects

W Chen

Publications and source records attributed to W Chen.

At least 613 records · Page 34Linked to original sources
PubMed1998

Genetic analysis enables definite and rapid diagnosis of cerebrotendinous xanthomatosis.

Mutations in the sterol 27-hydroxylase gene (CYP27) cause cerebrotendinous xanthomatosis (CTX). Early diagnosis of CTX is crucial because treatment with chenodeoxycholic acid can prevent or reverse some of the neurologic disability associated with the disease. We report the identification of three types of mutations (Arg441Trp, Arg372Gln, and Arg441Gln) in the CYP27 gene in five patients with suspected CTX from four unrelated families by restriction endonuclease analysis.

Adult↗
PubMed1998

Generation of mouse osteoclastogenic cell lines immortalized with SV40 large T antigen.

Progress in the field of osteoclast gene regulation has been hampered significantly by the lack of such cell lines. In this study, mouse osteoclast precursor cells were elicited in an osteoclast-inductive coculture system and immortalized using SV40 large T antigen. One of the osteoclast precursor cell lines (MOCP-5) forms 95% tartrate-resistant acid phosphatase positive (TRAP+) multinuclear osteoclast-like cells (OCLs) in the coculture system. The yield of TRAP+ OCLs was 4.5-7x10(4) cells per 10 cm2 dish. Expression of SV40 large T antigen was visualized in the nucleus of MOCP-5 cells and OCLs by immunohistochemistry. MOCP-5 cells were positive for MoMa-2 antigen and nonspecific esterase but negative for F4/80 antigen. OCLs derived from MOCP-5 cells were positive for able to form extensive resorption bone pits on bone slices. The resorbing activity of the OCLs was comparable to that of authentic mouse osteoclasts. Pit formation was inhibited by salmon calcitonin (CT). Acid production by OCLs was demonstrated by vital staining with acridine orange. The OCLs expressed cathepsin K and CT receptors. MOCP-5 cells could be transfected by a construct that carries the beta-galactosidase gene. Transfected MOCP-5 cells expressing beta-galactosidase retain the ability to differentiate into OCLs, indicating a useful model for osteoclast gene regulation. To date, the MOCP-5 cell line has been maintained in continuous culture for 23 months and has maintained the capacity to differentiate into osteoclasts throughout this time. In summary, these data show that a stable immortalized osteoclast precursor cell line has been established and that the immortalization with SV40 large T oncogene does not prevent osteoclast precursor cell differentiation.

Acid Phosphatase↗
PubMed1998

Chinese and American college students' body-image: perceived body shape and body affect.

This study examined the differences in the measures of perception of body shape and body affect among Chinese and American college male and female students. 289 Chinese students in China and 180 American students in the United States voluntarily completed the Body-image Questionnaire, comprised of four categories: (a) anthropometric data, (b) self-perception of body shape, (c) body affect, and (d) desired body shape. American students were significantly more likely than Chinese students to perceive their body shapes as being larger, but both Chinese and American students tended to perceive their body shapes accurately. For body affect, both Chinese and American female students who perceived themselves as thin had positive feelings about their bodies, while both groups of female students who perceived themselves as heavy had negative feelings about their bodies. American women were more likely than Chinese women to have negative feelings about their bodies. American students also placed high value on muscular firmness as part of their ideal female body shape, while Chinese students added plumpness as another component for judging ideal female body shape. Both Chinese and American men valued physical strength as a major component for body satisfaction.

Adult↗
PubMed1998

Chinese and American college students' motives for participation in physical activities.

To examine the differences in the current strengths of primary motives for participation in physical activities and exercises 289 Chinese students in China and 180 American students in the United States were administered the Motives for Activity Participation Questionnaire. Two-way analysis of variance indicated that American subjects spent significantly more time participating in physical activity and exercise than did Chinese subjects; men were significantly more likely than women to engage in physical activity and exercise. With respect to the motives for participation, multivariate analysis of variance showed an over-all significant difference on three factors of Weight/Body Management, Mental Health, and Social Interaction among the Chinese and American subjects. Subsequently, stepwise multiple regression analysis indicated that social interaction was the primary motive for American men and Chinese women. In contrast, management of body weight was the primary motive for American women.

Adolescent↗
PubMed1998

Biases associated with genotype and sex in prediction of fat-free lean mass and carcass value in hogs.

Carcass and live measurements of 165 market hogs that represented seven genotypes were used to investigate genotype and sex biases associated with the prediction of fat-free lean mass (FFLM) and carcass value. Carcass value was determined as the sum of the product of weight of individual cuts and their average unit prices adjusted for slaughter and processing costs. Independent variables used in the prediction equations included carcass measurements, such as optical probe, midline ruler, ribbed carcass measurements, and electromagnetic scanning (EMSCAN), and live animal ultrasonic scanning. The effect of including subpopulation mean values of independent variables in the prediction equations for FFLM and carcass value was also investigated. Genotype and sex biases were found in equations in which midline backfat, ribbed carcass, EMSCAN, and live ultrasonic scanning were used as single technology sets of measurements. The prediction equations generally undervalued genotypes with above-average carcass value. Biases were reduced when measurements of combined technologies and mean adjusted variables were used. The FFLM and carcass value of gilts were underestimated, and they were overestimated of barrows. Equations that combined OP and EMSCAN technologies were the most accurate and least biased for both FFLM and carcass value. Equations that included carcass weight and midline last-rib backfat thickness measurements were the least accurate and most biased. Genotype and sex biases must be considered when predicting FFLM and carcass value.

Adipose Tissue↗
PubMed1998

Polyketomycin, a new antibiotic from Streptomyces sp. MK277-AF1. I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

A new antibiotic designated polyketomycin was isolated from the culture broth of Streptomyces sp. MK277-AF1. It was purified by ethyl acetate extraction, Sephadex LH-20 column chromatography and centrifugal partition chromatography (CPC). It inhibited growth of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Its MICs were less than 0.2 microgram/ml. Polyketomycin exhibited cytotoxic activity against nine tumor cell lines at concentrations of 0.9-5.2 micrograms/ml.

Anti-Bacterial Agents↗
PubMed1998

Effect of acetylstrophanthidin on action potential duration and relation with extracellular potassium in sheep isolated Purkinje fibers.

AIM: To study the relation between the effect of acetylstrophanthidin on action potential duration (APD) and the extracellular potassium concentration. METHODS: Effect of acetylstrophanthidin (AS 0.15 mmol.L-1) on APD at different extracellular potassium concentrations was studied at the stimulation cycle lengths of 990 and 690 ms in sheep isolated cardiac Purkinje fibers using the standard microelectrode technique. RESULTS: At [K+]o 4.0 mmol.L-1, the biphasic effect of AS on APD appeared obviously. Both APD50 and APD90 were lengthened within the first 10 min of drug exposure. After 10 min, they were shortened at all pacing cycle lengths. On the other hand, at [K+]o 5.4 mmol.L-1, AS only shortened APD markedly without lengthening effect on it. The biphasic and monophasic effects of AS on APD were found at [K+]o 4.0 mmol.L-1 and 5.4 mmol.L-1, respectively. CONCLUSION: The effect of AS on APD was related to the concentration of [K+]o.

Action Potentials↗
PubMed1998

[Cromakalim inhibits endothelin-1 induced pulmonary hypertension in rats].

There is evidence that endothelin-1 (ET-1) and potassium channel may play an important role in the development of pulmonary hypertension. To evaluate the effect of ATP-sensitive K+ channel opener on pulmonary hypertension induced by ET-1, catheter was inserted into the pulmonary artery in ten male Wistar rats which had had pulmonary hypertension established by infusion of ET-1 (1.5 micrograms/kg), and then cromakalim were injected with a dose of 150 micrograms/kg. The mean pulmonary arterial pressure (mPAP), cardiac output (CO) monitored before and after infusion of ET-1, and 1 min, 5 min, 10 min after cromakalim injection, and pulmonary vascular resistance (PVR) were calculated. It was found that the mPAP was significantly increased, from 2.36 +/- 0.24 kPa to 3.32 +/- 0.49 kPa(P < 0.01), and PVR also increased, by infusion of ET-1. After cromakalim injection, mPAP were decreased to 2.50 +/- 0.62 kPa in 1 min, 1.14 +/- 0.18 kPa in 5 min and 2.33 +/- 0.52 kPa in 10 min, PVR decreased significantly. It is suggested that there is interaction between ET-1 and potassium Channel, and Cromakalim decreases mPAP in part by inhibiting the response of pulmonary artery to ET-1.

Animals↗
PubMed1998

[Changes of the gene expression of vascular endothelial growth factor in the lung of rats with chronic hypoxic pulmonary hypertension].

To observe the effect of chronic hypoxia on the gene expression of vascular endothelial growth factor (VEGF) in rat's lung, and the role of VEGF in the pathogenesis of hypoxic pulmonary hypertension, thirteen male Wistar rats were exposed to isobaric hypoxia for 3 weeks. The pulmonary artery pressure was measured by right cardiac catheterization. The serum level of VEGF was measured by Elisa. The VEGF cRNA was labeled with digoxigenin-UTP by in vitro transcription. The expression of VEGF mRNA in the lung was examined by hybridization in situ. The pulmonary artery pressure was significantly increased after hypoxic exposure. The serum level of VEGF in rats treated with hypoxia (420.3 +/- 73.1 pg/ml) was significantly increased in comparison with that of normal rats (322.2 +/- 58.1 pg/ml). The VEGF hybridization signals on the wall of pulmonary arteriole were significantly increased in rats with pulmonary hypertension. Chronic hypoxia can markedly increase expression of VEGF mRNA in the pulmonary arteriole and hence stimulate VEGF synthesis and secretion. The increase of VEGF may play a role in the developing process of hypoxic pulmonary hypertension.

Animals↗
PubMed1998

[Changes of level and distribution of vascular endothelial growth factor in the lungs of rats with hypoxic pulmonary hypertension].

This study was designed to elucidate whether the level and distribution of vascular endothelial growth factor (VEGF) are changed in the lungs of rats with hypoxic pulmonary hypertension. 13 male Wistar rats were exposed to isobaric hypoxia for 3 weeks. The pulmonary artery pressure was measured by right cardiac catheterization. The level of VEGF in pulmonary homogenate was measured by Elisa method. The distribution of VEGF in the rat lung was examined by immunohistochemistry. The results showed that the pulmonary artery pressure was significantly increased after hypoxic exposure. The level of VEGF in pulmonary homogenate of rats treated with hypoxia (466.9 +/- 75.5 pg/g) were significantly increased as compared with taht of normal rats (376.2 +/- 47.1 pg/g). The contents of VEGF in the wall of pulmonary arteriole were significantly increased in rats with pulmonary hypertension. So we suggest that chronic hypoxia can strongly stimulate VEGF secretion, and VEGF may mediate the process of hypoxic pulmonary vascular remodeling and pulmonary hypertension.

Animals↗
PubMed1998

[Isolation and identification of smooth muscle cells from pulmonary artery in rats].

To explore the method of isolating acutely the smooth muscle cells from pulmonary artery in rats, small pulmonary arteries (700-200 microns, ID) were dissected free of connective tissue and were allowed to digest in a N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid(HEPES)-buffered physiological saline solution (HPSS) containing collagenase, papain and bovine serum albumin. The tissue was then triturated to disperse smooth muscle cells. The isolated cells in suspension were identified and photographed with film on electron microscope (EM). We succeeded in isolating the single smooth muscle cell, which appeared compressed typically. 90% cells in suspension were identified smooth muscle cells on EM. We conclude that the method for isolation of pulmonary arterial smooth muscle cells is simple, stable and effective and is recommanded for use.

Animals↗
PubMed1998

[Change of level of basic fibroblast growth factor in serum of rats with chronic hypoxic pulmonary hypertension].

To evaluate the role of basic fibroblast growth factor (bFGF) in the development of hypoxic pulmonary hypertension, 30 wistar rats were divided into hypoxic group and control group. Rat models with chronic hypoxia induced pulmonary hypertension were established. The mean pulmonary artery pressure and the ratio of free wall of the right ventricular weight to the weight of the left ventricle septum were measured. The Level of bFGF in serum of rats with chronic hypoxic pulmonary hypertension was determined quantitatively by ELISA. Expresion of bFGF mRNA in lung, heart, brain and kidney of rats was observed by in situ hybridization using digoxigenin-labeled oligonucleotide probe. The result showed that the mPAP, the ratio of free wall of the right ventricular weight to the weight of the left ventricle plus septum, and the concentration of bFGF in serum were 3.96 +/- 0.47 kPa, 0.33% +/- 0.023%, 35.9 +/- 23.5 pg.ml-1 in rats exposed to hypoxia for 3 weeks, respectively; all were significantly higher than those in control group. Expression of bFGF mRNA in the wall pulmonary arterioles of rats with hypoxia was stronger than that of control group, but changes of expression of bFGF mRNA in heart, brain and kindey of rats were not observed. These suggest that bFGF takes part in reconstruction of pulmonary arterioles wall in chronic hypoxic pulmonary hypertension and bFGF in serum may be one of mechanism of modulating the structure remodeling of pulmonary arterioles.

Animals↗
PubMed1998

[The change of plasma level of endothelin in patients with acute attack of asthma].

In order to assess the interaction of endothelin (ET) and acute attack of asthma, the plasma levels of ET in 23 patients with acute attack of asthma and 12 normal controls were measured by radioimmunoassay. The partial pressure of oxygen in arterial blood (PaO2) and peak flow (PEF) were measured synchronously. The results showed that the plasma ET level in asthmatic patients (89.2 +/- 8.4 ng/L) was much higher than that in normal controls (52.2 +/- 6.5 ng/L), P < 0.001. There was a significant negative correlation between the plasma level of ET and the PaO2 (r = -0.7893, P < 0.01) or PEF (r = -0.7124, P < 0.01). The results suggest that ET may play a role in acute attack of asthma, and its level may stand for the degree of the disease.

Adolescent↗
PubMed1998

[Experimental study of apoptosis induced by cisplatin in human ovarian carcinoma AO 10/17 cells].

OBJECTIVE: Whether apoptosis induced by cisplatin resulted in tumor growth inhibition and the relationships between apoptosis and cell cycle, intracellular and extracellular Ca++ concentration were investi- gated. METHODS: AO 10/17 cells were treated with cisplatin. Morphological changes (HE stain) were observed under light microscope; DNA degradation was assayed by electrophoresis on agarose gel. The change of cell cycle was analyzed by flow cytometer and cytosolic Ca++ concentrations were monitored using probe of calcium ion fluo-3/AM. RESULTS: Under the influence of cisplatin, AO 10/17 cells exhibited changes of apotosis both in morphology and in the characteristics of electrophoresis. Meanwhile the cell cycle also showed special change and intracellular Ca++ concentration was increased. Increase in extracellular Ca++ concentration when AO 10/17 cells were treated with CaCl2 and cisplatin did not enhance the efficacy of cisplatin. CONCLUSION: The results suggest that apoptosis followed by change of cytosolic Ca++ concentration is one of the mechanism of cisplatin in inhibition of ovarian tumor growth. It is closely related to cell cycle.

Antineoplastic Agents↗
PubMed1998

[Telomerase activity in human gastric and colorectal cancer].

OBJECTIVE: To study telomerase activity in patients with gastric and colorectal cancer. METHODS: Telomerase activity in tumor samples, including 9 colonic, 20 rectal and 11 gastric carcinomas, was examined by telomeric repeat amplification protocol(TRAP) assay. Thirty-nine samples from tumor-adjacent tissues were also assayed. RESULTS: Ninety per cent(36 out of 40 tumor samples) exhibited telomerase activity regardless of tumor stage or differentiation. However, telomerase activity in the tumor-adjacent tissues could be detected only in 1 of 39 specimens. CONCLUSION: Telomerase may be a good diagnostic biomarker for tumor detection.

Adult↗
PubMed1998

Methylation of p16 gene in hematological malignancies.

OBJECTIVE: To investigate the incidence of p16 gene methylation in hematological malignancies, and the relations between p16 gene methylation and the prognosis of hematological malignancies. METHODS: Fifty-five patients were studied by restriction enzyme polymerase chain reaction (PCR) to detect p16 gene methylation. RESULTS: p16 gene methylation was detected in 6 of 55 patients (10.9%), who were 1 patient with M2a, 1 patient with M5a, 2 patients with chronic myelogenous leukemia (CML) in blast crisis, 1 patient with progressing multiple myeloma (MM), 1 with non-Hodgkin's lymphoma (NHL) accompanied by B-ALL, respectively. p16 gene methylation correlates with adverse prognostic features. The patients with p16 gene methylation had poor response to therapy, and died shortly after p16 gene methylation was detected. CONCLUSION: The methylation of p16 gene plays an important role in the pathogenesis and the development of some hematological malignancies. The patients with p16 gene methylation have poor prognosis. The detection of p16 gene is a useful tool for evaluating prognosis of hematological malignancies.

DNA Methylation↗
PubMed1998

[The inhibition effect of acute hypoxia on K+Ca-ATP channels of pulmonary artery smooth muscle cells of rats].

OBJECTIVE: To explore the possible mechanism underlying hypoxic pulmonary vasoconstriction, we evaluated the effect of acute hypoxia on potassium channels in pulmonary artery smooth muscle cells. METHOD: The single smooth muscle cell was freshly isolated from pulmonary artery (phi 700-200 microns) of Wistar rats with acute enzymatic digestion method. In symmetrical high K+ solution, we separated one outward K+ current from the patch of smooth muscle cells with inside-out configuration using patch-clamp technique. According to the electrophysiological response to the patch channel, this current was identified as the Ca2+, ATP activated potassium channel (K+Ca-ATP). The hypoxic solution was obtained by aeration with 5% CO2-balance N2 mixture. RESULT: The currents of K+Ca-ATP in the patch of smooth muscle cells was much inhibited while the oxygen tension of solution was reduced from normoxic (PO2 > or = 13.33 kPa) to hypoxic (PO2 < or = 2.67 kPa) levels (P < 0.01). Cromakalim (10 nmol/L), an opener of potassium channel, could activate the currents of K+Ca-ATP decreased by acute hypoxia (P < 0.01). CONCLUSION: Acute hypoxia has an inhibition role on K+Ca-ATP currents in pulmonary artery smooth muscle cells, causes the membrane potentional depolarization, leads to pulmonary vasoconstriction, increases pulmonary vascular resistance and artery pressure. The decrease of K+Ca-ATP contributes to development of hypoxic pulmonary vasoconstriction. Cromakalim is one of effective antagonists for hypoxic pulmonary vasoconstriction.

Animals↗