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Biomedical subjects

W Chen

Publications and source records attributed to W Chen.

At least 847 records · Page 47Linked to original sources
PubMed1996

[Experimental study of immunity in anti-plasmodium infection on preserved spleen and splenectomized mice].

OBJECTIVE: To investigate the function of the spleen as well as the changes of splenic function after hemisplenectomy and hemisplenic autotransplanted in plasmodium yoelili infected mice (first and second infection). METHODS: 336 mice were divided into six groups: 1. total splenectomy, 2. hemisplenectomy, 3. hemisplenic autotransplanted, 4. sham-operation, 5. total splenectomy of 2nd infection, 6. sham-operation of the 2nd infection. 3 months after operation (1-4) or 15 day after 1st infection and operation (5-6) in mice intraperitoneal inoculations were initiated. RESULTS: 1. First infection: in total splenectomy group the antiplasmodium antibody reduced, the remanent rate of 51Cr-RBC in circulation was high, RBC count continously decreased, parasitized erytrocytes still were seen after 1 month. These changes were mild in the preserved spleen. But the production of antiplasmodium antibody and spleen uptake rate of 51Cr-RBC of the hemisplenic autotrans aplaned were rather lower than those of the shamoperate group. 2. Second lethal yoelli infection: in the mice of shamoperation of 2nd yoelii infection the parasitized erytrocyte was lower than that of shamoperated group, but the higher level antiplasmodium antibody and uptake rates of 51Cr-RBC of unit weight splenic tissue. CONCLUSIONS: Under the plasmodium infection preserved hemispleen alternate normal spleen to play the immunologic role, splenic tissue autotransplantation can fairly restore the partial function of spleen. Different preserved spleen method is a useful operation for clinic.

Animals↗
PubMed1996

[CD4+ T-cell immunity and Ab responses to mutant ras protein in pancreas and colon cancer patients].

Mutated p21 ras protein contains single substituted amino acid residue. It can be considered as cancer-specific protein. The current study examined whether T-cell and Ab responses to mutant p21 ras protein and/or peptide can be detected in patients with pancreatic or colon cancer. Studies focused on the aspartic acid substitution in amino acid position 12(ras D12) as the commonest mutation in gastrointestinal malignancy. IgA antibodies directed against mutated ras D12 protein were detected in 51 of 160 (31.8%) colon cancer patients, but only in 1 of 40 (2.5%) normals. The greater incidence of antibody in cancer patients provides evidence that immunization to the ras proteins occurred as a result of the malignancy. Seven of sixteen (43.7%) pancreas cancer patients responded to ras D12 peptide. T cell responses to ras D12 peptides were detected in only 2 of 25 (8.0%) colon cancer patients. None of the 11 normal individuals tested had positive responses to normal or mutant ras p21 proteins and/or peptides. Thus, Ab and CD4+ T cell immunity to the mutated segment of ras protein is present in some patients with gastrointestinal cancer.

CD4-Positive T-Lymphocytes↗
PubMed1996

The expression of c-erbB-1 and c-erbB-2 oncogenes in basal cell carcinoma and squamous cell carcinoma of skin.

The expression of c-erbB-1 and c-erbB-2 oncogenes were investigated by immunohistochemistry using monoclonal antibodies to c-erbB-1 and c-erbB-2 protein in 43 cases of basal cell carcinoma (BCC) and 26 cases of squamous cell carcinoma (SCC). We found that the expression of c-erbB-1 oncogene in all BCC increased by different degrees and the expression of c-erbB-2 oncogene in BCC was significantly reduced or lost when compared to that in normal epidermal cells. Furthermore, apparent negative and positive relationships were observed respectively between the tumor differentiation and the expression of c-erbB-1 and c-erbB-2 oncogenes in SCC. It is suggested that the abnormal expression of c-erbB-1 and c-erbB-2 oncogenes in BCC and SCC may play a role in the development of skin tumors. The pattern of the c-erbB-1 and c-erbB-2 oncogenes expression in SCC may assist in distinguishing the biological behavior and prognosis of SCC.

Adolescent↗
PubMed1996

[Evaluation of therapeutic effects of moist burn ointment and betadine ointment in treatment of severe burn].

In order to compare the therapeutic value of moist burn ointment (MBO) and betadine ointment in severe burns, the authors divided 30 patients with burn over 30% TBSA into two groups. In one group MBO was used, and in another group betadine was used. The result showed; 1. The difference between two groups was not great in superficial II degree burn wound. 2. MBO was less effective than betadine in deep burn wound. MBO had little antibacterial effect, wound healing was delayed, and incidences of infection, complication and mortality were higher. At the same time, MBO did not have noticeable effect in inhibiting scar hypertrophy. The authors suggest that MBO must be used with caution in severe burn patients, especially in the southern provinces where the climate is hot and humid.

Administration, Topical↗
PubMed1996

Functional maturation of mouse CD4+CD8- thymocytes induced by medullary-type thymus epithelial cells.

Murine CD4+CD8-(CD4SP) thymocyte subset is a heterogeneous population, in which the Qa-2- cells are less functional, whereas the Qa-2+ cells are fully functional. Evidence is provided here that the transition from Qa-2- to Qa-2+ CD4SP thymocytes is an intrathymic process of differentiation induced by thymic medullary-type epithelial cells. The separated Qa-2-CD4SP could be induced to express Qa-2 molecules up to 84%-89% of the total viable cells after cocultured for 3 d with MTEC1 cells, a murine thymic medullary type epithelial cell line established in our laboratory. Kinetic study showed that both the percentage of Qa-2+ cells and the density of the expressed Qa-2 molecules on CD4SP thymocytes induced by MTEC1 were progressively increasing in 72-h cultures. The MTEC1-induced Qa-2+CD4SP thymocytes were fully functional, which exhibited capabilities of proliferation and cytokine secretion in response to Con A stimulation as high as those of freshly isolated Qa-2+CD4SP thymocytes. The profile of cytokines secreted by MTEC1-induced Qa-2+CD4SP thymocytes was Thy 0 type specified by the production of IL-2, IL-4 and IL-6. The results suggest that Qa-2-CD4SP thymocytes may give rise to the Qa-2+CD4SP thymocytes, and acquire fully functional competence in thymic medulla under the foster of local epithelial cells.

Animals↗
PubMed1996

[Effect of tetrandrine on calmodulin activity of lung tissue in rats with hypoxic pulmonary hypertension].

OBJECTIVE: The mechanism that tetrandrine (Tet) reduces hypoxic pulmonary hypertension was investigated METHOD: 30 Wistar rats were divided into normal control group, pulmonary hypertension group and tetrandrine-treated group. Total calcium conteins and calmodulin activity in lung tissue were measured with atomic absorption spectrophotometry and phosphodiesterase method. RESULTS: The results showed that Tet could remarkably reduce the mean pulmonary artery pressure and pulmonary vascular resistance in rats with hypoxic pulmonary hypertension, the contents of calcium (62 +/- 10 umol.g-1) and calmodulin (20 +/- 4 ng.mg-1) in the lung were significantly lower in rats administrated with Tet than those (74 +/- 16 umol.g-1, 27 +/- 6 ng.mg-1) rats with hypoxic pulmonary hypertension, and the contents of calcium were related with the mean pulmonary artery pressure and pulmonary vascular resistance in the lung administrated with Tet. CONCLUSION: The results indicated the mechanism that tetrandrine effectively reduces hypoxia pulmonary hypertension may be associated with decreasing intracellular calcium concentration in vascular smooth cells, and the effect may be a result of anti-calmodulin activity.

Alkaloids↗
PubMed1996

[Change of tumor necrosis factor and interleukin-6 in brochoalveolar lavage fluid of allergic asthma].

OBJECTIVES: To explain the change of TNF-alpha, IL-6 biological activity in supernatant of cultured AM and in BALF in the athmatic animal. METHOD: The guinea pig model of asthma was established by frestly immunizing and then challenging the animal with 1% ovalbumin; The level of TNF-alpha and IL-6 were measured by L929 cytotoxic test and by the MH60. BSF2 cell proliferation test. RESULTS: TNF-alpha and IL-6 in BALF and supernatant of AM in asthmatic animals were increased significantly, and there was a strong correlation between TNF-alpha and IL-6. CONCLUSIONS: TNF-alpha and IL-6 might play a key role in the allergic airway inflamination and AM might be the source of TNF-alpha and IL-6.

Animals↗
PubMed1996

[The cloning and expression of salmon calcitonin gene in Escherichia coli].

The DNA fragment encoding salmon calcitonin was separated from the salmon DNA with PCR method. It was recombined into the fusion expression vector (pGEX-2T) which included a Glutathion-S-Transferase (GST) gene and was transformed into E. coli JM109 and then expression was induced with IPTG. The fusion protein (GST-sCT) accounted for 38%-40% of the total cellular protein and was purified from the soluble expression products by glutathion sepharose 4B affinity chromatography. The purity of GST-sCT is about 80% and it showed a positive immunological reaction in calcitonin enzyme immunoassay.

Amino Acid Sequence↗
PubMed1996

[Effects of ginkgo plus on hypoxic pulmonary hypertension in rats].

We examined the effects of Ginkgo Plus on the pulmonary hemodynamics and right ventricular hypertrophy in rats exposed to isobaric chronic hypoxia. The rats treated with chronic hypoxia developed pulmonary hypertension and right ventricular hypertrophy. Ginkgo Plus reduced significantly the hypoxia-induced increase of mean pulmonary arterial pressure and pulmonary vascular resistance as well as the ratio of right ventricular weight vs left ventricular plus septal weights. The results suggested that Ginkgo Plus could relieve the hypoxic pulmonary hypertension.

Animals↗
PubMed1996

[The level of platelet activating factor in blood of rats with hypoxic pulmonary hypertension].

Because hypoxia is a known predisposing factor for pulmonary hypertension, we investigated the effects of hypoxia and platelet activating factor (PAF) on the development of pulmonary hypertension in rats. Male Wistar rats were made hypoxic by placing them in a isobaric hypoxic chambar (O2 = 10%) for 3 weeks; the rats developed pulmonary hypertension and right ventricular hypertrophy. We found that PAF level in blood of rats were significantly elevated at 2-3 weeks of hypoxia (280.8 +/- 119.7 ng/ml and 324.2 +/- 67.6 ng/ml vs 148.3 +/- 60.2 ng/ml). Therefore, we conclude that PAF plays a central role in mediating hypoxia-induced pulmonary hypertension.

Animals↗
PubMed1996

[The role of platelet activating factor in chronic pulmonary hypertension].

To investigate the chronic effects of platelet activating factor (PAF) on pulmonary circulation, we administered PAF to 15 male Wistar rats in low doses by intraperitoneal injection for 28 days. The results showed that after PAF treatment the mean pulmonary arterial pressure increased by 1.17 kPa, the pulmonary vascular resistance increased by 2409.3 kPa.s/L, the cardiac output decreased by 9.1 ml/min and the ratio of right ventricular weight to left ventricular plus septal weights increased by 0.1, compared with control. Histologic sections of the lungs were examined under light microscope equipped with a computerized image analyser. The wall of pulmonary arterioles was thickened; the percent of vascular wall thickness/vascular external diameter and percent of vascular wall area/total vascular area were increased in the PAF group (P < 0.05). These suggest that PAF may play an important role in the pathogenesis of chronic pulmonary hypertension.

Animals↗
PubMed1996

[Changes on level and expression of endothelin-1 in the lungs of rats with hypoxic pulmonary hypertension].

The aim of the present study was to determine whether mRNA for endothelin-1 (ET-1) was present and changed in the lungs of rats exposed to chronic hypoxia, cRNA probes for rat ET-1 and c-fos were labelled by in vitro transcription with digoxigenin-UTP for in situ hybridization. Endothelin-1 like immunoactivity (ET-1-LI) in plasma as well as in lung homogenate was measured by radio-immunoassay. The results showed that the vascular endothelia cells of pulmonary artelics and the bronchiolar epithelial cells were strongly positive for the ET-1 probe. The perivascular and peribronchiolar smooth muscle were positive for the c-fos probe primarily. Whereas, there were little expression of ET-1 and c-fos in the rat lungs in controls. There were significant increase of ET-1-LI levels in rats exposed to hypoxia for 3 weeks, the concentration in venous samples was 3.85 +/- 1.52ng/L (P < 0.05 as compared with the control groups), in arterial sample was 4.72 +/- 1.66ng/L (P < 0.05) and in lung tissue was 2.06 +/- 0.68ng/g wet lung weight (P < 0.05). It is suggested that chronic hypoxia elevated the mean pulmonary arterial pressure, caused vessel remodelling and right ventricular hypertrophy. These changes were accompanied by an increase of ET-1 in plasma and lung homogenate. The expression and production of ET-1 were localized to endothelium and airway epithelium in the lungs.

Animals↗
PubMed1995

Characterization of a silencer element in the first exon of the human osteocalcin gene.

Osteocalcin, the major non-collagenous protein in bone, is transcribed in osteoblasts at the onset of extracellular matrix mineralization. In this study it was demonstrated that sequences located in the first exon of the human osteocalcin gene possess a differentiation-related osteocalcin silencer element (OSE). Osteocalcin was rendered transcribable in UMR-106 cells and proliferating normal osteoblasts after deletion of the -3 to +51 region. Site-specific mutagenesis of this region revealed that a 7 bp sequence (TGGCCCT) (+29 to +35) is critical for silencing function. Mobility shift assays demonstrated that a nuclear factor bound to the OSE. The OSE binding protein was present in proliferating normal pre-osteoblasts and in UMR-106 and ROS 17/2.8 osteosarcoma cells, but was absent from post-proliferative normal osteoblasts. The binding protein was inhibited by fragments containing the +29/+35 sequence, but not by other promoter fragments or by the consensus oligomers of unrelated nuclear factors AP-1 and Sp1. DNase 1 footprinting demonstrated that the OSE binding-protein protected the +17 to +36 portion of the first exon, consistent with the results of mapping studies and competitive mobility shift assays. It is hypothesized that this silencer is activated by complexing of the OSE binding protein to the OSE during the osteoblast proliferation stage and that the OSE binding protein is down-regulated at the onset of extracellular matrix mineralization.

Animals↗
PubMed1995

Frequent somatic hypermutation of the 5' noncoding region of the BCL6 gene in B-cell lymphoma.

The BCL6 gene encodes a zinc-finger transcription factor and is altered by chromosomal arrangements in its 5' noncoding region in approximately 30% of diffuse large-cell lymphoma (DLCL). We report here that, in 22/30 (73%) DLCL and 7/15 (47%) follicular lymphoma (FL), but not in other tumor types, the BCL6 gene is also altered by multiple (1.4 x 10(-3) -1.6 x 10(-2) per bp), often biallelic, mutations clustering in its 5' noncoding region. These mutations are of somatic origin and are found in cases displaying either normal or rearranged BLC6 alleles indicating their independence from chromosomal rearrangements and linkage to immunoglobulin genes. These alterations identify a mechanism of genetic instability in malignant B cells and may have been selected during lymphomagenesis for their role in altering BCL6 expression.

Alleles↗
PubMed1995

Differential suppression of charge movement components by gluconate in cut twitch fibres of Rana temporaria.

1. Charge movement was studied in cut twitch fibres of Rana temporaria using a double Vaseline-gap voltage-clamp technique. 2. Replacement of Cl- by gluconate in the external solution reduced the magnitude of the early current component (I beta) substantially but affected the magnitude and slowed the kinetics of the hump current component (I gamma) slightly. 3. The early (Q beta) and hump (Q gamma) charge components in the gluconate solution were 11.8 +/- 2.3 and 88.0 +/- 4.8% (mean +/- S.E.M., n = 9), respectively, of those in the Cl- solution. 4. These results suggest that Q beta cannot be a precursor of Q gamma. Moreover, since fibres bathed in a gluconate solution can release calcium, Q beta is probably not involved in triggering calcium release.

Animals↗
PubMed1995

Chromosomal assignment of human ID1 and ID2 genes.

The Id (inhibitor of DNA binding) proteins regulate transcription during development by interacting with transcription factors. Three human genes, ID1, ID2, and ID3, have been identified that belong to this family of transcription regulators. We show, by somatic cell hybridization and fluorescence in situ hybridization experiments, that ID1 and ID2 are localized at 20q11 and 2p25, respectively.

Blotting, Southern↗