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Biomedical subjects

M Chen

Publications and source records attributed to M Chen.

At least 487 records · Page 27Linked to original sources
PubMed1997

Ultraviolet A irradiation upregulates type VII collagen expression in human dermal fibroblasts.

Type VII collagen, a major component of skin-anchoring fibrils, is synthesized by both fibroblasts and keratinocytes, the two principal cell types in the skin. In this study, we examined the effects of ultraviolet A (UVA) irradiation on the expression of type VII collagen in human fibroblasts. UVA irradiation (0-15 J/cm2) caused a dose-dependent increase (5- to 10-fold) in type VII collagen mRNA levels as detected by northern blot analysis. The UVA-induced enhancement of type VII collagen gene expression correlated with an increase in its protein level by immunoblot analysis of proteins secreted into the conditioned medium. The effect of UVA was observed at 12 h and reached its maximum by 18 h. Under these conditions, however, the expression of fibronectin, a major dermal matrix protein, remained unchanged, suggesting that the induction of type VII collagen expression was selective. Actinomycin D, a transcription inhibitor, blocked the UVA-mediated induction of type VII collagen gene expression, whereas cycloheximide, a protein synthesis inhibitor, superinduced the expression of type VII collagen, suggesting that de novo protein synthesis was not required for the action of UVA. Interestingly, in contrast to the increased type VII collagen expression in fibroblasts in response to UVA, a slight decrease in type VII collagen mRNA level was observed in the UVA-irradiated keratinocytes, suggesting that the effect of UVA on the type VII collagen expression is cell type specific.

Adult↗
PubMed1997

Detection of hepatitis G virus (GB virus C) RNA in human saliva.

Using PCR and genomic sequencing, we confirmed the presence of and homology between hepatitis G virus (HGV) (also called GB virus C) RNA in six serum samples and that in two saliva samples obtained from 34 patients with chronic hepatitis C virus infections. Thus, HGV may be found outside the circulatory system.

Amino Acid Sequence↗
PubMed1997

Characterization of humoral and CD4+ cellular responses after genetic immunization with retroviral vectors expressing different forms of the hepatitis B virus core and e antigens.

The humoral and CD4+ cellular immune responses in mice following genetic immunization with three retroviral vectors encoding different forms of hepatitis B virus core antigen (HBcAg) and e antigen (HBeAg) were analyzed. The retroviral vectors induced expression of intracellular HBcAg (HBc[3A4]), secreted HBeAg (HBe[5A2]), or an intracellular HBcAg-neomycin phosphoryltransferase fusion protein (HBc-NEO[6A3]). Specific antibody levels and immunoglobulin G isotype restriction were highly dependent on both the host major histocompatibility complex and the transferred gene. Humoral and CD4+ cellular HBcAg and/or HBeAg (HBc/eAg)-specific immune responses following retroviral vector immunization were of a lower magnitude but followed the same characteristics compared with those after immunization with HBc/eAg in adjuvant. Two factors influenced the humoral responses. First, in vivo depletion of CD8+ cells in HBc-NEO[6A3]-immunized H-2k mice abrogated both HBcAg-specific antibodies and in vitro-detectable cytotoxic T lymphocytes. Second, priming of H-2b mice with an HBc/eAg-derived T-helper (Th) peptide in adjuvant prior to retroviral vector immunization greatly enhanced the HBc/eAg-specific humoral responses to all three vectors, suggesting that insufficient HBc/eAg-specific CD4+ Th-cell priming limits the humoral responses. In conclusion, direct injection of retroviral vectors seems to be effective in priming HBc/eAg-specific CD8+ but comparatively inefficient in priming CD4+ Th cells and subsequently specific antibodies. However, the limited HBc/eAg-specific CD4+ cell priming can effectively be circumvented by prior administration of a recombinant or synthetic form of HBc/eAg in adjuvant.

Animals↗
PubMed1997

The casein kinase II beta subunit binds to Mos and inhibits Mos activity.

Mos is a germ cell-specific serine/threonine kinase and is required for Xenopus oocyte maturation. Active Mos stimulates a mitogen-activated protein kinase (MAPK) by directly phosphorylating and activating MAPK kinase (MKK). We report here that the Xenopus homolog of the beta subunit of casein kinase II (CKII beta) binds to and regulates Mos. The Mos-interacting region of CKII beta was mapped to the C terminus. Mos bound to CKII beta in somatic cells ectopically expressing Mos and CKII beta as well as in unfertilized Xenopus eggs. CKII beta inhibited Mos-mediated MAPK activation in rabbit reticulocyte lysates and repressed MKK activation by v-Mos in a coupled kinase assay. In addition, microinjection of CKII beta mRNA into Xenopus oocytes inhibited progesterone-induced meiotic maturation and MAPK activation, presumably by binding of CKII beta to Mos and thereby inhibiting MAPK activation. Moreover, this inhibitory phenotype could be rescued by another protein that binds to CKII beta, CKII alpha. The ability of ectopic CKII beta to inhibit meiotic maturation and the detection of a complex between endogenous Mos and CKII beta suggest that CKII beta may act as an inhibitor of Mos during oocyte maturation, perhaps setting a threshold beyond which Mos protein must accumulate before it can activate the MAPK pathway.

Amino Acid Sequence↗
PubMed1997

DHEA protects against visceral obesity and muscle insulin resistance in rats fed a high-fat diet.

Visceral obesity is frequently associated with muscle insulin resistance. Rats fed a high-fat diet rapidly develop obesity and insulin resistance. Dehydroepiandrosterone (DHEA) has been reported to protect against the development of obesity. This study tested the hypothesis that DHEA protects against the increase in visceral fat and the development of muscle insulin resistance induced by a high-fat diet in rats. Feeding rats a diet providing 50% of the energy as fat for 4 wk resulted in a twofold greater visceral fat mass and a 50% lower rate of maximally insulin-stimulated muscle 2-deoxyglucose (2-DG) uptake compared with controls. Rats fed the high-fat diet plus 0.3% DHEA were largely protected against the increase in visceral fat (+ 11.3 g in high fat vs. + 2.9 g in high fat plus DHEA, compared with controls) and against the decrease in insulin-stimulated muscle 2-DG uptake (0.94 +/- 0.15 mumol.ml-1.20 min-1, controls; 0.46 +/- 0.06 mumol.ml-1.20 min-1, high-fat diet; 0.78 +/- 0.07 mumol.ml-1.20 min-1, high fat + DHEA). DHEA did not affect food intake. These results show that DHEA has a protective effect against accumulation of visceral fat and development of muscle insulin resistance in rats fed a high-fat diet.

Animals↗
PubMed1997

Activation-secretion coupling in 10P2 murine mast cells challenged with IgE-antigen, ionophore A23187, thapsigargin and phorbol ester.

Mast cell activation-secretion by several signal transduction pathways results in the release of proinflammatory mediators including histamine, proteases, arachidonic acid metabolites and multifunctional cytokines. In the present investigations the activation-secretion responses of the cytokine-independent, cloned 10P2 cell line have been explored. [14C]Serotonin (5-HT) preloaded cells were stimulated with antigen, with and without IL-4, ionophore A23187, thapsigargin or phorbol myristate acetate (PMA). Following passive sensitization with anti-dinitrophenol (anti-DNP) IgE, mast cells released up to 31% of incorporated [14C]5-HT when stimulated with specific antigen (DNP-human serum albumin). This response was potentiated by pretreatment with IL-4. Significant degranulation (50%) was noted following treatment with calcium ionophore A23187, thapsigargin and ionophore A23187/PMA. Collectively, these results suggest that 10P2 cells undergo activation-secretion responses, assessed as degranulation of preloaded [14C]5-HT when challenged with IgE antigen, by influx of extracellular calcium or release of intracellular calcium stores, or by direct activation of protein kinase isozymes. As a growth factor-independent cell line, 10P2 cells may be a valuable adjunct to existing mast cell model systems currently used for pharmacologic investigations.

2,4-Dinitrophenol↗
PubMed1997

Cisplatin, doxorubicin, and cyclophosphamide plus thoracic radiation therapy for limited-stage unresectable thymoma: an intergroup trial.

PURPOSE: To determine the response rate of cisplatin plus doxorubicin plus cyclophosphamide (PAC) in patients with limited-stage unresectable thymoma. In addition, this study was undertaken to determine the toxicity, progression-free survival, and overall survival of combined-modality therapy with PAC plus radiation therapy. PATIENTS AND METHODS: Patients with a histologic diagnosis of limited-stage unresectable thymoma or thymic carcinoma were eligible. Further requirements included a Karnofsky Performance Score of > 60, no prior radiation to the chest, and adequate bone marrow, hepatic, and renal function. No patient had undergone chemotherapy previously. Patients received two to four cycles (repeated every 3 weeks) of cisplatin (50 mg/m2), doxorubicin (50 mg/m2), and cyclophosphamide (500 mg/m2) followed by a total dosage of 54 Gy to the primary tumor and regional lymph nodes for patients with a stable, partial, or complete response to chemotherapy. RESULTS: From November 1983 through January 1995, 26 patients were entered onto the trial. Three patients were ineligible on the basis of pathologic review (lung cancer, germ cell cancer, lymphoma). Toxicity, primarily hematologic, was mild, with only one early death due to a perforated abdominal viscus. Among the 23 assessable patients, there were five complete and 11 partial responses to chemotherapy (overall response rate, 69.6%). The median time to treatment failure was 93.2 months (range, 3 to 99.2+ months), and the median survival time was 93 months (range, 1 to 110 months). The 5-year survival rate is 52.5%. CONCLUSIONS: PAC combination chemotherapy produces response rates in the management of patients with limited thymoma. Combined-modality therapy is feasible and associated with prolonged progressive-free survival. The benefit of combined-modality therapy over radiation therapy alone is suggested for patients with unresectable thymoma.

Adult↗
PubMed1997

[Preliminary study on relationship among apoptosis and related gene, prognosis of lung cancer].

OBJECTIVE: To observe the relationship among Lung cancer cell apoptosis, proliferation and related gene expression and its significance as an index of prognosis. METHOD: In situ end labelling (ISEL) technique and DNA gel electrophoresis were used to detect the apoptotic cell, immunohistochemistry was used to detect the expression of bcl-2, P53 and ki-67 in 57 cases of Lung cancer. RESULT: The number of apoptotic cells was found to correlated with the ratio of ki-67 positive cell (P = 0.001). There was significant correlation between the extent of apoptosis and the expression of bcl-2 in SCLC, but this relation was not observed in NSCLC. No correlation was found among apoptotic cells or ki-67 positive cells, staging, age and expression of P53. Patients with apoptotic cells greater than 3% and ki-67 greater than 20% possessed shorter survival time than that less than or equal to 3% or 20%, respectively (P = 0.0057, P = 0.002 by log ronk). CONCLUSIONS: Increased apoptotic and proliferous cells are independent prognostic index in lung cancers, predicting shortened survival time of the patients.

Adenocarcinoma↗
PubMed1997

[Bronchofiberscope and catheter intervention in treatment of multi-drug resistant pulmonary tuberculosis].

OBJECTIVE: To evaluate the clinical value of bronchofiberscope and catheter intervention in treatment of multi-drug resistant pulmonary tuberculosis. METHOD: Forty-eight patients with multi-drug resistant pulmonary tuberculosis were treated by injecting ofloxacin and amikacin through bronchofiberscope and catheter in addition to chemotherapy, while forty controls were treated by chemotherapy only. RESULT: At the end of the treatment, the sputum conversion rate was 92%, radiographic improvement rate 96% and cavity closing rate 27% in the treatment group, all of which were higher than the controls (63%, 58% and 10% respectively) (P < 0.01-0.05). No complication and obvious adverse reaction were observed. CONCLUSION: The efficacy of bronchofiberscope and catheter intervention in addition to chemotherapy is better than only chemotherapy in treatment of multi-drug resistant pulmonary tuberculosis.

Adult↗
PubMed1997

[Endoscopic papillosphincterotomy for the treatment of pancreaticobiliary disease].

From July 1987 to March 1996, endoscopic papillosphincterotomy (EST) was performed in 346 patients of 2,700 cases undergoing ERCP. Maj or indications for EST were choledocholithiasis, constrictive papillitis, chronic pancreatitis, biliary ascariasis and dysfunction of Oddi's sphincter. The EST was successful in 331 cases, ang the overall success rate was 95.7%. The stone discharge rate was 96%. The stricturotomy rate was 93.8%. The failure rate was 4.3% (15 cases). Clinical application and prevention of complications for EST were discussed.

Adult↗
PubMed1997

[The antibacterial activity of cefmetazole and other antibiotics to 463 isolates].

We compared the in-vitro antibacterial activity of cefmetazole and other 4 antibiotics against clinical isolates. The minimal inhibitory concentration (MIC) of cefmetazole against 463 isolates was determined by standard (NCCLS) agar dilution testing, and compared with that of cefazolin, cefuroxime, cefotaxime and ceftazidime. The results showed that cefmetazole was the most effective in 5 antibiotics to indole (+)P. vulgaris and M. morganii (MIC(90) 8 mg/L), and cefmetazole had the same activity as cefotaxime (sensitive 82%-100%), but less activity than ceftazidime (sensitive 88%-100%) against E. coli, K. pneumoniae and P. morabilis. To oxacillin-sensitive staphylococci, cefmetazole was highly active, with the MIC 90 of 4 mg/L. Our results indicate that cefmetazole is highly active against Enterobacteriaceae and oxacillin-sensitive staphylococci.

Cefmetazole↗
PubMed1997

[Change of serum soluble vascular cell adhesion molecule-1 in patients with acute cerebral infarction and its clinical significance].

The aim of this study is to characterize the pattern of release of soluble vascular cell adhesion molecule-1 (sVCAM-1) in patients with acute cerebral infarction. The level of serum sVCAM-1 was measured serially with two-layer antibody sandwich enzyme-linked immunosorbent assay (ELISA) in 89 patients with acute cerebral infarction, 43 patients with cerebral haemorrhage and 30 normal controls. It is shown that the level of serum sVCAM-1 in patients with cerebral infarction 24 hours after the onset was higher than that in patients with cerebral haemorrhage and normal controls (P < 0.01). The level of serum sVCAM-1 was significantly higher in the patients with large cerebral infarction than that in patients with medium and small cerebral infarctions (P < 0.01). The level of serum sVCAM-1 in patients with cerebral infarction increased from 24 hours to 7 days and decreased from 7 days to 14 days, but it was still higher than that in patients with cerebral haemorrhage and normal controls on the 14th day. The level of serum sVCAM-1 was higher in patients with infection as compared with those without. These findings suggested that sVCAM-1 is closely related to the development of acute cerebral infarction. It is essential to have further study on the change of serumsVCAM-1 in cerebral infarction.

Aged↗
PubMed1997

[Expression of vasoactive intestinal peptide receptor in human colonic carcinoma cell membranes].

To evaluate the expression of vasoactive intestinal peptide receptor in colonic carcinoma cell membranes in men and to assess the relationship between the receptor characteristics and the histopathologic features, the authors labelled vasoactive intestinal peptide and measured vasoactive intestinal peptide receptor sites with radio-ligand bind assay on 12 specimens from colon cancer and its adjacent normal tissues. The number of the vasoactive intestinal peptide receptor sites of colon cancer was significantly smaller than that of the adjacent normal tissues (2.66 +/- 3.84 pmol/mg versus 10.54 +/- 17.99 pmol/mg, and the number of the receptor sites of colon cancer was not well related to the degrees of cancer differentiation. This study has laid the basis for the regulation of the receptor-ligand binding to inhibit the growth of colon cancer.

Adenocarcinoma↗
PubMed1997

[Effect of butachlor on CH4 emission and anaerobes in paddy soil].

Effects of butachlor on CH4 emission and the count of anaerobes in paddy soil or in the media were studied. The results obtained showed that CH4 emission and growth of methanogens would be greatly affected at field rates of butachlor within 2 weeks, but this adverse effects would disappear as time went on. CH4 emission and methanogenic activities would be retarded by butachlor in media for longer time. The amount of butachlor available to act upon anaerobes depended on application rate and method of application.

English Abstract↗
PubMed1997

[Effects of HE particles on medicinal plant Agastache rugosus (Fisch. et Mey.) O. Ktze].

The biological effect of HE particles on the seeds of Agastache rugosus was probed in experiments on board a retrievable satellite. The result shows that the germination rate of the seeds pierced by HE particles radiation appears rather low. The seeds hit by HE particles (piercing radiation or not) start to germinate two days earlier than those in the control group, and the first leaf emerges four to five days earlier than that in the control group. The resultant seedlings grow markedly faster. Variations take place in the nuclear types of chromosome. The yield of essential oils becomes slightly higher. No marked changes have been observed in the major chemical components of these oils.

Chromosomes↗