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W Chen

Publications and source records attributed to W Chen.

At least 1,045 records · Page 58Linked to original sources
PubMed1993

Characterization of a membrane-associated ATPase from Methanococcus voltae, a methanogenic member of the Archaea.

A membrane-associated ATPase with an M(r) of approximately 510,000 and containing subunits with M(r)s of 80,000 (alpha), 55,000 (beta), and 25,000 (gamma) was isolated from the methanogen Methanococcus voltae. Enzymatic activity was not affected by vanadate or azide, inhibitors of P- and F1-ATPase, respectively, but was inhibited by nitrate and bafilomycin A1, inhibitors of V1-type ATPases. Since dicyclohexylcarbodiimide inhibited the enzyme when it was present in membranes but not after the ATPase was solubilized, we suggest the presence of membrane-associated component analogous to the F0 and V0 components of both F-type and V-type ATPases. N-terminal amino acid sequence analysis of the alpha subunit showed a higher similarity to ATPases of the V-type family than to those of the F-type family.

Adenosine Triphosphatases↗
PubMed1993

Altered jejunal potassium (Rb+) transport in piglet rotavirus enteritis.

To determine the mechanisms of K+ loss in viral diarrhea, K+ fluxes (estimated by tracer Rb+ flows) across piglet jejunum in Ussing chambers were determined. Normal jejunum was characterized by an indomethacin-sensitive short-circuit current and a small K+ secretory flow. Rotavirus-infected gut secreted K+ at high rates, probably resulting from increased prostaglandin generation because secretion was abolished by indomethacin. Tissues pretreated with indomethacin responded to 8-bromoadenosine 3',5'-cyclic monophosphate acid and 16,16-dimethyl-prostaglandin E2 with K+ secretion. The secretory response in rotavirus-infected jejunum was no greater than that in normal tissue. Serosal addition of Ca2+ ionophore A23187 caused K+ secretion in normal but not rotavirus-infected jejunum. To inhibit the basolateral uptake of K+ and reduce the driving force for secretion, ouabain was added to the bath. Ouabain unmasked a K+ absorptive process in normal intestine, which was not seen in rotavirus-infected tissue. K+ absorption was inhibited by 3-(cyanomethyl)-2-methyl-8-(phenyl-methoxy)imidazo (1,2 alpha)pyridine (Sch-28080) and omeprazole. We speculate that the high fecal K+ losses observed in human rotavirus enteritis might be caused by an imbalance between K+ secretion and an impaired apical K+ absorptive mechanism in the crypt-type epithelium.

Acute Disease↗
PubMed1993

Palatability of prerigor cooked boar meat.

Cooking reduces odor intensity in boar meat but also may induce lipid oxidation unless the meat pH is above approximately 6.0. This research was designed to determine the feasibility of cooking boar meat in the prerigor state to overcome boar odor and lipid oxidation problems. Prerigor and postrigor triceps brachii muscle samples from 40 boars (20 Duroc and 20 Yorkshire) were cooked to 60 degrees C, frozen and stored at -20 degrees C, reheated in a 60 degrees C water bath for 1 h, and then subjected to pH, thiobarbituric acid (TBA), and sensory analyses. Boar odor intensity and skatole concentration in backfat samples were determined by olfactory test and HPLC, respectively. Cooked (initial cooking) prerigor meat was found to have higher (P < .05) pH and lower (P < .05) TBA values than comparable postrigor meat (6.44 vs 6.09 and 2.15 vs 3.23, respectively). Regression analysis indicated an inverse relationship between pH and TBA values (r = -.52; P < .01). No appreciable changes in TBA values were noted after frozen storage for 14 to 98 d, but reheating increased TBA values (P < .05) in both prerigor and postrigor samples (3.45 vs 4.32, respectively). Sensory evaluation scores indicated that prerigor cooked meat was less tender with more pronounced rancid flavor than postrigor cooked meat (P < .05), but panelists may have allowed the toughness of the prerigor samples to adversely affect their flavor scores. No difference in boar odor was detected between rigor states or breeds. Mean skatole concentration in backfat was .12 micrograms/g and no difference was detected between breeds.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1993

Experimental study of the effect of IH764-3 on pulmonary fibrosis.

IH764-3 is a potent component isolated from Salvia miltiorrhiza. We have studied the effect of IH764-3 on experimental pulmonary fibrosis in rats and mice treated with a single intratracheal instillation of bleomycin-A6. Three groups of animals were assigned as BLM+saline, BLM+IH764-3 and normal control. The results indicated that in the treated group, lung coefficient, surfactant, hydroxyproline content and FGF activity were significantly lower than those in the control group (P < 0.05, 0.05, 0.001 and 0.05, respectively). Electron microscopic examination showed that pulmonary ultrastructure was markedly better in the treated group: type II alveolar epithelial cells, infiltrating inflammatory cells, proliferating collagen-forming cells, collagen and elastic fibers were obviously fewer in the treated group. These results demonstrate that IH764-3 has prophylactic and therapeutic effects on pulmonary fibrosis.

Animals↗
PubMed1993

[Schistosoma japonicum adult worm RNA isolation with Chomczynski's method].

A rapid method of total RNA of Schistosoma japonicum adult worm isolation by single step extraction with an acid guanidinium thiocyanate-phenol-chloroform mixture is described. The method provides a pure preparation of intact RNA and can be completed within several hours. It is particularly useful for isolation of RNA from minute quantity of parasite material. Analysis of agarose gels electrophoresis reveals that the RNA preparations show a distinct band comigrating with 18S rat brain RNA and without large rRNA species. The large rRNA is in vivo nicked. The absence of a band at approximately 26S presumably reflects post transcriptional processing of the large rRNA.

Animals↗
PubMed1993

Primary structure, neural-specific expression, and dendritic location of human BC200 RNA.

Primate BC200 RNA is a 200-nucleotide-long, nontranslatable RNA that is prevalently expressed in the nervous system. We have determined the primary structure of human BC200 RNA, using cDNA cloning and PCR techniques. BC200 RNA can be subdivided into three structural domains. The 5' region is homologous to Alu repetitive elements that are found in high copy numbers in primate genomes. The central part of BC200 RNA is characterized by a high percentage of A-residues, with a few interspersed other nucleotides. The 3' sequence is unique to BC200 RNA and shows no apparent similarity with known human DNA sequences. Sequence similarity with rodent BC1 RNA is limited to several short elements, and BC1/BC200 sequence comparisons indicate that the two genes have evolved via separate phylogenetic routes. Probes directed against the 3' unique part of BC200 RNA detected a single band corresponding to approximately 200 nucleotides on RNA blots. This band was identified only with RNA isolated from human brain, not with RNA from non-neural organs such as lung or kidney. In situ hybridization to selected areas of the human nervous system showed that BC200 RNA is expressed by a subpopulation of neurons that is analogous to the BC1 RNA-expressing subset of neurons in the corresponding areas of the rat nervous system. Moreover, like rat BC1 RNA, human BC200 RNA was localized to dendrite-rich neuropil areas, for example, in the inner plexiform layer of the retina. These results indicate that BC1 RNA and BC200 RNA, although of different evolutionary pedigree, may play analogous functional roles, in rodents and primates, respectively, in somatodendritic domains of nerve cells.

Base Sequence↗
PubMed1993

Characterization of seven newly established nasopharyngeal carcinoma cell lines.

BACKGROUND: Nasopharyngeal carcinoma (NPC) has a relatively high incidence in Chinese living in Taiwan, Hong Kong, Singapore, and South China. To better understand this cancer, we have established several new NPC cell lines. EXPERIMENTAL DESIGN: We collected biopsy specimens from suspected NPC patients and divided each specimen into two parts: the first part was fixed for routine histopathologic examination, and the other part was put into culture medium for primary culture. Once the cell lines were established, they were extensively characterized. RESULTS: Seven NPC cell lines were established, and all have been passaged more than 100 times. Two lines were derived from keratinizing carcinomas and five from undifferentiated carcinomas. Electron microscopic examination revealed that both dark and light tumor cells contained intermediate filaments with clear desmosome formation. The average doubling time ranged from 10.7 to 16.3 hours. Karyotypic analysis showed multiple chromosome abnormalities with the average chromosome number between 84 and 95. Colony forming efficiency in soft agar was 18-42%. All cell lines could induce solid tumor mass formation when transplanted into nude mice, and the histopathological findings showed two keratinizing and five nonkeratinizing carcinomas. All cell lines contained less acidic keratin polypeptides than basic keratin polypeptides. Strong expression of vimentin in each single cell of all cell lines was also observed. The oncosuppressor retinoblastoma gene in each cell line showed no remarkable abnormality, but retinoblastoma protein was abnormally expressed in some interphase cells. The oncogenes, erbB and c-fgr, were both normally expressed. While the c-myc oncogene in all cell lines was overexpressed when compared with the Burkitt's lymphoma Raji Cell line, the c-myc DNA sequence in each cell line showed neither amplification nor rearrangement. CONCLUSIONS: The newly established seven NPC cell lines have been well characterized, and all showed overexpression of c-myc oncogene. The oncosuppressor retinoblastoma gene revealed no remarkable rearrangement, but its protein product was abnormal in certain interphase cells of each cell line.

Adult↗
PubMed1993

[Weight-for-length index in evaluation of children's body weight status: a simple and accurate method].

This study examines the weight-for-length index (WLI)--weight/height/the WLI constant, where the WLI constant is the ratio between the 50th percentile weight and height for the age and sex--for its appropriateness in estimating the status of body weight among school children. The WLI constant has been calculated for practical use and rapid calculation. Using the known percentile data in the Taiwan area, this report shows evidence that the WLI constant has changed a little during the past 30 years. On theoretical grounds, it seems that the WLI is a valid index because it is independent of the progressing physical growth of children it Taiwan. Data were obtained for a sample of 5,214 healthy boys and 5,607 healthy girls ages 5 to 14, attending schools in Taipei, Taiwan. The WLI was found to be a satisfactory measure of relative weight as has been generally found for the body mass index (weight/height2) because it has little correlation with age (r = 0.07) and only a fair correlation with height (r = 0.26) for the whole sample of children. In an attempt to offer support for the findings, the relationship between WLI and the overweight index (actual weight/average weight for sex, age and height) were evaluated. The correlations between the WLI and the overweight index were excellent for each sex grouping (r = 0.91 for boys and 0.89 for girls). The results also suggest that the WLI appears to be a very accurate measure of obesity (sensitivity: 88.3-92.1%, specificity: 86.9-89.9%) for all the school children in this sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[RFLP analysis of DNA from Echinococcus granulosus collected from four provinces/autonomous region in China].

A fragment of the ribosomal RNA gene of Schistosoma mansoni pSM889 and two DNA fragments specific to Echinococcus granulosus pHD5 and pEG18 have been used as DNA probes to assess the extent of genetic variability within E. granulosus. The DNA analysis, including restriction endonuclease digestion and Southern blot hybridization with the probes, did not demonstrate any genetic variation among E. granulosus collected from sheep in Xinjiang, Qinghai, Gansu and Ninxia. Similarly, there was no genetic variation among E. granulosus isolates collected from yak in Qinghai and Gansu provinces. The authors deemed that the yak isolates and the sheep isolates of E. granulosus appear to belong to a same strain.

Animals↗
PubMed1993

[Parent-directed weight reduction program for obese children: model formulation and follow-up].

To investigate the effect of a parent-directed weight reduction program on childhood obesity, a prospective 12-month follow-up study was performed at an outpatient clinic in a district general hospital. Sixty obese children, who, together with their parents received a free of charge weight reduction program, were compared with 52 obese controls who refused the program. The program included knowledge of childhood obesity and ways to decrease calories and increase physical activity; emphasized family participation and behavior modification; and stressed parent direction and self-responsibility. Complete outcome information relating to weight and height changes and a compliance questionnaire was available for 70.5% of these children after 1 year. Twenty three (48.9%) of the 47 children in the treatment group showed a decrease in the percentage they were overweight, compared to only six (18.8%) of the 32 control children. The mean changes in percentage overweight showed a decrease of 2.3% for the treatment children and an increase of 3.1% for the control children. Of the 23 children who were more successful during therapy, two had normal weight, 5 were overweight and 16 remained obese. Child height was not changed after weight reduction in those children in the treatment group who were more successful. The degree of compliance was significantly correlated to the change in percentage overweight. A decrease in percentage overweight was not significantly predicted by sex, age, or severity of obesity of the children, nor by whether the children were excessive eaters or partook in insufficient physical activity prior to the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[Studies on the strain differences of Schistosoma japonicum in the mainland of China. XII. DNA hybridization of five isolates].

The nonradioactive labelled probe pSM 889 was hybridized to Southern blots of genomic DNA of five isolates of Schistosoma japonicum from Anhui, Hubei, Guangxi, Sichuan and Yunnan in the mainland of China. The major bands of hybridization of DNA digested by restriction endonucleases EcoRI and BamHI are same among the five isolates, but the minor bands of hybridization of DNA digested by EcoRI show some differences between 4.4-9.6 kb and between 2.3-4.4 kb among the five isolates. The result shows that the five isolates are of some genetic variation. It provides, at molecular level, evidence of the existence of different strains of S. japonicum in the mainland of China.

Animals↗
PubMed1993

[Characterization of Echinococcus granulosus and Echinococcus multilocularis by DNA probe].

Cloned DNA fragments pHD5, pSM889 and pEG18 have been used as DNA probes in the restriction endonuclease analysis and southern blot hybridization to characterize E. granulosus and E. multilocularis protoscolices from China. Southern blot hybridization method is sensitive, specific and has the advantage in identification over microscopic examination. The authors deem that it can be used in the base-line epidemiological survey and surveillance of hydatid disease to provide data for hydatid disease control.

Animals↗
PubMed1993

A domestic cell bioreactor and its application in virus culture.

A cell culture bioreactor (CellCul-20) and its application in cell and virus culture are described in this paper. It has been evaluated with strict aseptic tests and one-year's operation shown that CellCul-20 bioreactor can keep its aseptic condition after being autoclaved. It can meet the requirement for the control of the main parameters for cell and virus culture and the finely adjustment of the main parameters to meet the changing conditions of the cultivation. A high cell density and a high level of virus titre were reached respectively for Vero cells and Japanese encephalitis virus (JEV) while they were cultured in this bioreactor. It is the first report on large-scale culture of JEV-infected Vero cells to prepare primary JEV vaccine. Some suggestions are made for the improvement of CellCul-20.

Animals↗
PubMed1993

[Regulation of glycogenolysis against hormones in isolated rat hepatocytes].

cAMP and Ca(2+)-dependent glycogenolytic pathways are regulated by different hormones involved in the activation of glycogen phosphorylase in isolated rat hepatocytes. Dose-dependent glucagon activation of glycogen phosphorylase and lowering of cAMP levels were obtained by vasopressin and angiotensin treatment. Similar time courses of Ca2+ fluxes and phosphorylase activation were induced by vasopressin, angiotensin and phenylephrine. Heterologous down-regulation of hormones was induced in glycogenolysis in hepatocytes. These results could be of significance in physiology studies in vivo.

Angiotensin II↗
PubMed1993

[The changes in the levels of angiotensins and angiotensin converting enzyme and effects of captopril in patients with hypoxic pulmonary hypertension].

The levels of angiotensin I, II (ATI, II) and angiotensin converting enzyme (ACE) were measured in 28 patients with hypoxic pulmonary hypertension and 23 normal individuals. The effects of captopril were observed in 8 of 28 patients. The results showed that the average level of ATII in the patients was significantly higher than that in normal control (P < 0.05), but the average level of ACE in the patients was significantly lower than that in the controls (P < 0.05). In 8 patients, after the use of captopril, an ACE inhibitor, for two weeks, the levels of ATII, ACE and mean pulmonary arterial pressure (mPAP) were markedly decreased (P < 0.05). But the other 20 patients treated with antibiotics, antiasthmatics, diuretics and oxygen therapy for two weeks did not show any alterations in the levels of ATII, ACE and mPAP.

Aged↗
PubMed1993

Relation of IL-2, IL-3 and IL-4 with allergic asthma induced by spores of mushroom (Pleurotus sapidus).

The effects of IL-2, IL-3, and IL-4 activities on occurrence of allergic asthma induced by spores of mushroom have been studied by measuring the IL-2, IL-3, and IL-4 activities in culture supernatants of spleen lymphocytes from guinea pigs being stimulated with Con A. The IL-4 activity (14.9 +/- 0.18 u) in the culture supernatant was higher than control group (6.7 +/- 1.5 u). The IL-2 and IL-3 activities were all similar to that of the control group. The IL-4 synthesis was similarly raised as the IL-4 activity. These results indicated that there is a relationship between the occurrence of allergic asthma and the increase of IL-4.

Animals↗
PubMed1993

[Grafting of autogenous jugular vein and glutaraldehyde-stabilized human umbilical vein in dogs].

The glutaraldehyde-stabilized human umbilical cord vein (HUV) was implanted to the intrarenal aorta in dogs, by using autogenous jugular vein (AJV) as control. The healing mechanism was shown by angiography, radioisotope scanning Doppler ultrasound, LM, SEM and TEM. The patency rate in 6 months was 95.2% in AJV and 87.5% in HUV. No significant difference was noted between the two veins (P > 0.05). Pathohistological study of AJV and HUV after implantation showed that there were three stages: acute injury, acute inflammatory reaction and hyperplastic repairing of tissues. The new endothelial cells of AJV grew earlier and faster than those of HUV. But, both veins were endothelialized 6 months after operation. The subendothelium of new intima consisted of fibroblasts and collagen fibres less myointimal cells derived from smooth muscle cells in the media. The media and the adventilized were replaced by fibrous connective tissue. HUV stabilized with 0.5% glutaraldehyde for grafting caused no immunologic rejection, and had the structure of the venous wall and antithrombotic function, keeping the grafts patent.

Animals↗