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Biomedical subjects

Feng Wang

Publications and source records attributed to Feng Wang.

At least 235 records · Page 13Linked to original sources
PubMed2002

Resection of pancreatic cancer normalizes the preoperative increase of tumor necrosis factor alpha gene expression.

BACKGROUND: Tumor necrosis factor alpha (TNF-alpha) appears to play a role in the cachexia and diabetes seen in patients with cancers. However, increased TNF-alpha is seen in some, but not all, of the cancer patients. METHODS: The mRNA transcripts of TNF-alpha and its receptors (TNF-RI and TNF-RII) were quantified in blood cells of pancreatic cancer patients, using competitive quantitative reverse transcriptase-polymerase chain reaction. Plasma TNF-alpha was also quantified in these patients by enzyme-linked immunosorbent assay. Control blood came from healthy subjects. RESULTS: The TNF-alpha mRNA transcripts (per microgram of total RNA) were increased in pancreatic cancer patients (6.8 +/- 2.1 x 10(6), n = 10), compared to control (1.2 +/- 0.2 x 10(6), n = 9, p < 0.05). After the tumour was removed, the TNF-alpha mRNA transcripts were reduced to a level (2.1 +/- 0.8 x 10(6)) similar to the control. In the cancer patients, no significant changes were found in TNF-RI and TNF-RII gene transcription, compared to the controls. CONCLUSION: The expression of the TNF-alpha gene is upregulated in patients with pancreatic cancer and normalized after the pancreatic tumor is removed. These results are consistent with the concept that TNF-alpha is involved in metabolic disorders associated with pancreatic cancer.

Adult↗
PubMed2002

Specific amino acid profile in culture media conditioned by human pancreatic cancer cell lines.

BACKGROUND: In malignant diseases, circulating amino acid profiles correlate with organ sites of malignancy. Direct effects of malignant cells on the extracellular amino acid profile are still uncertain. METHODS: Free amino acids were measured in serum-free culture media (RPMI-1640) conditioned by two human pancreatic cancer cell lines (Panc-1 and HPAF), a hamster pancreatic cancer cell line (PC-1), a human epidermoid carcinoma cell line (A-431), and a human fibroblastic cell line (Ag-1523). Non-conditioned RPMI-1640 medium was used as control. RESULTS: Amino acid profiles were changed in all the conditioned media, caused by a decrease or increase in the original amino acids and by the appearance of amino acids that were not present in non-conditioned medium. Media conditioned by two human pancreatic cancer cell lines showed similar amino acid profiles, which were characterized by a decrease in glutamine, cysteine and serine, increase in glycine, proline and glutamic acid and appearance of ornithine and alanine. CONCLUSION: Culture media show changed amino acid profiles following incubation with cell lines of pancreatic or non-pancreatic origins. Different human pancreatic cancer cell lines cause similar changes in amino acid profiles of media.

Amino Acids↗
PubMed2002

Early impairment of insulin secretion in rats after surgical trauma.

OBJECTIVE: Hyperglycaemia associated with insulin resistance is common after trauma and surgical procedures. Both reduced insulin sensitivity and altered insulin secretion may contribute to the impaired glucose homeostasis. We have demonstrated that skeletal muscle insulin resistance is present 2 h after small intestinal resection in rats. In this study, the aim was to investigate insulin secretion in the same experimental model. DESIGN: Small intestinal resection (5 cm) was performed in adult rats. The control animals underwent anaesthesia only. METHODS: The intravenous glucose tolerance test (IVGTT), the hyperglycaemic clamp and in vitro studies in isolated pancreatic islets were performed after surgery. Concentrations of blood glucose, plasma insulin, corticosterone and interleukin-6 (IL-6) were determined 0-5 h postoperatively. RESULTS: The insulin response in the IVGTT was attenuated 2 h (P<0.05) but not 4 h or during the hyperglycaemic clamp (3.5-4.5 h) postoperatively. Insulin secretion in response to glucose in vitro was decreased 2 h after the surgery (P<0.05), but no change was seen in arginine-stimulated secretion. Plasma levels of corticosterone were increased 3.5-5 h postoperatively (P<0.001-0.05). Increases in IL-6 were also seen postoperatively. CONCLUSION: We demonstrate that glucose-induced, but not arginine-induced, insulin secretion is temporarily impaired after intestinal resection in rats. The later appearance of elevated corticosterone and IL-6 levels, as well as the preservation of the beta-cell inhibition in vitro, argues against the possibility that these two circulating factors are causally responsible for reduced insulin release seen after surgery in this model.

Animals↗
PubMed2002

The concurrent accumulation of intra-abdominal and subcutaneous fat explains the association between insulin resistance and plasma leptin concentrations : distinct metabolic effects of two fat compartments.

Obesity is associated with insulin resistance, particularly when body fat has a central distribution. However, insulin resistance also frequently occurs in apparently lean individuals. It has been proposed that these lean insulin-resistant individuals have greater amounts of body fat than lean insulin-sensitive subjects. Alternatively, their body fat distribution may be different. Obesity is associated with elevated plasma leptin levels, but some studies have suggested that insulin sensitivity is an additional determinant of circulating leptin concentrations. To examine how body fat distribution contributes to insulin sensitivity and how these variables are related to leptin levels, we studied 174 individuals (73 men, 101 women), a priori classified as lean insulin-sensitive (LIS, n = 56), lean insulin-resistant (LIR, n = 61), and obese insulin-resistant (OIR, n = 57) based on their BMI and insulin sensitivity index (S(I)). Whereas the BMI of the two lean groups did not differ, the S(I) of the LIR subjects was less than half that of the LIS group. The subcutaneous and intra-abdominal fat areas, determined by computed tomography, were 45 and 70% greater in the LIR subjects (P < 0.001) and 2.5- and 3-fold greater in the OIR group, as compared with the LIS group. Fasting plasma leptin levels were moderately increased in LIR subjects (10.8 +/- 7.1 vs. 8.1 +/- 6.4 ng/ml in LIS subjects; P < 0.001) and doubled in OIR subjects (21.9 +/- 15.5 ng/ml; P < 0.001). Because of the confounding effect of body fat, we examined the relationships between adiposity, insulin sensitivity, and leptin concentrations by multiple regression analysis. Intra-abdominal fat was the best variable predicting insulin sensitivity in both genders and explained 54% of the variance in S(I). This inverse relationship was nonlinear (r = -0.688). On the other hand, in both genders, fasting leptin levels were strongly associated with subcutaneous fat area (r = 0.760) but not with intra-abdominal fat. In line with these analyses, when LIS and LIR subjects were matched for subcutaneous fat area, age, and gender, they had similar leptin levels, whereas their intra-abdominal fat and insulin sensitivity remained different. Thus, accumulation of intra-abdominal fat correlates with insulin resistance, whereas subcutaneous fat deposition correlates with circulating leptin levels. We conclude that the concurrent increase in these two metabolically distinct fat compartments is a major explanation for the association between insulin resistance and elevated circulating leptin concentrations in lean and obese subjects.

Abdomen↗
PubMed2002

Effect of N-desulfated heparin on hepatic/renal ischemia reperfusion injury in rats.

AIM: To investigate the effect of N-desulfated heparin on hepatic/renal ischemia and reperfusion injury in rats. METHODS: Using rat models of 60 minutes hepatic or renal ischemia followed by 1 h,3 h,6 h and 24 h reperfusion,animals were randomly divided into following groups,the sham operated controls,ischemic group receiving only normal saline,and treated group receiving N-desulfated heparin at a dose of 12 mg/kg at 5 minutes before reperfusion. P-selectin expression was detected in hepatic/renal tissues with immunohistochemistry method. RESULTS: P-selectin expression, serum ALT, AST, BUN and Cr levels were significantly increased during 60 minute ischemia and 1 h, 3 h, 6 h and 24 h reperfusion,while the increment was significantly inhibited,and hepatic/renal pathology observed by light microscopy was remarkably improved by treatment with the N-desulfated heparin. Furthermore,the heparin was found no effects on PT and KPTT. CONCLUSION: P-selectin might mediate neutrophil infiltration and contribute to hepatic/renal ischemia and reperfusion. The N-desulfated heparin might prevent hepatic/renal damage induced by ischemia and reperfusion injury without significant anticoagulant activity.

Alanine Transaminase↗
PubMed2002

[In vivo expression of human tissue-plasminogen activator transfected AGZY83-a cells implanted in mice].

OBJECTIVE: To detect the expressing levels of human tissue-plasminogen activator(t-PA) in AGZY83-a cells transfected with pcDNA3.1(+) t-PA in vivo and the feasibility of using transplantation of cells for gene therapy of thrombotic diseases. METHODS: Expression vectors containing the t-PA cDNA gene were transfected into AGZY83-a cells. The transfected AGZY83-a cells were implanted into mice in different regions, and the plasma levels of human t-PA were assayed at intervals. RESULTS: The plasma levels of human t-PA were significantly increased in mice after implantation of transfected AGZY83-a cells and were significantly higher than those of control groups implanted with untransfected AGZY83-a cells. This significant increase lasted at least 105 days. The intraperitoneal implantation group expressed the highest level of human t-PA, a little higher than that of the subcutis implantation group, while both are much higher than that of the quadriceps femoris implantation group which expressed the lowest. CONCLUSION: The implanted transfected AGZY83-a cells are able to stably express high levels of human t-PA, and transplantation of cells transfected with pcDNA3.1(+) t-PA is a new promising method for gene therapy of thrombotic diseases.

Animals↗
PubMed2002

[Inhibitation of tumor angiogenesis, growth and metastasis by blocking VEGF paracrine pathway].

Solid tumors require an adequate vascular supply to grow beyond a certain dimension. It is known that formation of new blood vessels in tumor is mediated by unbalanced expression of angiogenic factors and their inhibitors. Among the former, the vascular endothelial growth factor (VEGF) has been assumed prime candidacy as a major positive physiological effector. To investigate the role of VEGF in angiogenesis associated with development of breast cancer, a sense VEGF and an anti-sense VEGF expression plasmids were constructed, and then were introduced into a human breast carcinoma cell line, MCF-7, expressing middle level of endogenous VEGF. Anti-sense VEGF(121) transfected MCF-7 cells that expressed reduced constitutive levels of VEGF and showed the same growing potential as untransfected MCF-7 cells in vitro, but it showed longer latency, smaller tumor, slower growth and prolonged survival time compared to parental or sense VEGF(165) transfected MCF-7 cells in vivo. Moreover, the tumors derived from anti-sense VEGF(121) transfected MCF-7 cells characterized by minimal vascularization and extensive necrosis. Finally, mice with primary subcutaneous tumors treated with intratumoral administration of anti-sense VEGF, or the plasmid expressing extracellular domain of the Flk-1 VEGF receptor (sFlk-1) followed by electroporation, showed significant tumor suppression. These results suggest that VEGF plays a major angiogenic role in breast cancer and a strategy, which blocks the VEGF paracrine pathway, may provide a means to control tumor growth topically without the risk of systemic antiangiogenesis.

3T3 Cells↗
PubMed2002

[Obtaining stem borer-resistant homozygous transgenic lines of Minghui 81 harboring novel cry1Ac gene via particle bombardment].

A modified cry1Ac gene was generated by fusing with Lys-Asp-Glu-Lue (KDEL), an endoplasmic reticulum retention signal at the 3'-ends, with signal peptide coding sequence of Soybean kunitz trypsin inhibitor (SKTI) at the 5'-ends. Vector containing the modified cry1Ac gene coding region flanked by the corn ubiquitin 1 promoter and the nopaline synthase gene (nos) terminator with Hygromycin Phosphotransferase (hpt) gene as a plant selection marker was constructed. The modified cry1Ac gene in which toxic protein targeted to endoplasmic retention was successfully transferred into Minghui 81 (Oryza sativa L. subsp. indica), an elite restoring line of commercial CMS indica hybrid rice, through particle bombardment and obtained fertile transformants. Homozygous transgenic rice lines were obtained in the third generation exploiting self-seed set reproduction and HygromycinB selection. These transgenic lines were confirmed with polymerase chain reaction (PCR) amplification, Southern blotting and ELISA detection. Pest insect-resistant bioassay indicated that some of the homozygous cry1Ac-transgenic rice plants of T2 progeny showed high-level resistance against striped stem borer (Chilo suppressalis) at field trials.

Animals↗
PubMed2002

TNF-alpha and the phenotypic transformation of human peritoneal mesothelial cell.

OBJECTIVE: To investigate if tumor necrosis factor-alpha (TNF-alpha) could induce phenotypic transformation or the associated cell function changes of human peritoneal mesothelial cells (HPMCs). METHODS: All tests were performed on the human peritoneal mesothelial cell line (HMrSV5, kindly donated by Prof. Pierre RONCO). Morphological changes of HPMCs were observed by phase contrast microscopy. The expressions of cytokeratin 8, cytokeratin 18 and vimentin were detected by immunocytochemistry. mRNA expressions of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) were detected by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). Production of MMP-9 and type I collagen was measured by enzyme-linked immunosorbent assays. RESULTS: TNF-alpha (1 - 10 ng/ml) induced morphological changes in about 50% - 60% of human peritoneal mesothelial cells (HPMCs). The original polygonal cobblestone monolayer was changed into elongated, spindle-shape characteristic of fibroblasts. The original strong positive expression of cytokeratin 8 and cytokeratin 18 was changed in all morphologically changed HPMCs to negative, but the expression of vimentin maintained positive. By 4-hour treatment with TNF-alpha (1 - 10 ng/ml), mRNA expression of MMP9 was significantly up-regulated, and mRNA expression of TIMP-1 and TIMP-2 were down-regulated. We also observed that the production of MMP-9 and type I collagen increased significantly after 24-hour treatment with TNF-alpha. CONCLUSION: 24-hour treatment with TNF-alpha, produced a partial transformation of HPMCs into the fibroblast phenotype. TNF-alpha treatment of HPMCs up-regulated the synthesis of MMP-9 and type I collagen, which may facilitate peritoneal extracellular matrix remodeling and fibrogenesis.

Cell Line↗
PubMed2002

[Long-term outcome of gfp gene modified human RPE xenografts into the subretinal space of rabbits].

The possibility of delivery genes to retina by using retinal pigment epithelium (RPE) transplantation was investigated. Cultured human adult RPE cells were transfected with retrovirus encoding green fluorescent protein (GFP), then GFP-expressing RPE cells were transplanted into the subretinal space of rabbits through pars plana vitrectomy under microscopy. The transplant sites were examined in vivo by ophthalmoscope for fluorescence. The animals were euthanatized at 1, 2, 3, 4, 6, 10, 11, 14, 18, 20, 23, 24, 25, 33, 54 weeks, respectively, and the retinas were studied histologically, including epi-fluorescent microscopy, confocal microscopy and transmission electron microscopy. The GFP-expressing transplant could be followed in the living retina up to 21 days by ophthalmoscope. The epi-fluorescent microscopy examination disclosed survival of the transplanted cells in 1 year with continual and significant GFP expression. It was observed the transplanted hRPE-gfp cells were not only present at transplant sites but spread over two to three quarters of retina. Generally, RPE xenografts integrated individually into host RPE in a regular cobblestones arrangement or formed a monolayer sheet between host RPE and neural retina. It was observed that intravitreal injection of FK-506 weekly improved the survival of RPE xenografts and reduced the infiltration of mononuclear microphages and lymphocytes in choroids from 1 through 14 weeks after transplantation. The results demonstrate a long-term survival of gene modified human RPE xenografts into the subretinal space of rabbits and support the feasibility of this approach for delivery genes to retina.

Adult↗
PubMed2002

[Liposome-mediated gene transfer into retina].

OBJECTIVE: To evaluate the efficiency of liposome mediated gene transfer to retina, the time of gene expression in retinal cells, retinal damage caused by liposome and the possibility of using liposome mediated gene transfer to retina for treating fundus diseases. METHODS: The ratio of cationic liposome to green fluorescein protein (GFP) expression plasmid for high efficacy of transfection was tested in vitro. Then optimal liposome-plasmid mixture was injected into the subretinal space of Sprague-Dawley (SD) or Royal college of surgeon (RCS) rats. The GFP expression was observed by using fluorescence microscopy, and morphological changes were examined by using paraffin embedded sections, HE staining and transmission electron microscopy. RESULTS: The GFP expression in retinal cells was observed lasting more than 4 weeks. However, upon 4 weeks of transfection the swelling and degeneration in outer segment of photoreceptors could be observed. The aggravated degeneration with disappearance of outer segments, only one layer of photoreceptor nucleus surviving, apoptotic inner granular layer cells and neovascularization were observed 8 weeks after transfection. But no inflammatory cells were observed. Three of 5 RCS rats that received plasmid pCNTF (ciliary neurotrophic factor) delivery at 4 weeks old showed more surviving nuclei of photoreceptors after 3 to 5 weeks of transfection. CONCLUSION: Liposome is able to deliver genes to retinal cells with efficacy, and the expression of therapeutic gene such as CNTF in retinal cells can rescue photoreceptors from degeneration. But liposome used here is to some extent harmful to photoreceptors.

Animals↗
PubMed2002

[Clinical analysis of 333 cases of inhalation injury in burned children].

OBJECTIVE: To analyze the clinical features of inhalation injury in children, with the aim of improving its management. METHODS: The incidence of inhalation injury in 333 cases of burned children was analyzed in terms of burn area, shock, infection and prognosis. RESULTS: The incidences of shock and bacteremia were 41.14% and 18.92%, and those of moderate and severe inhalation injury were 58.76% and 31.96% respectively in burned children with inhalation injury. Bacteremia developed in 24.82% of the patients with shock. Among 67 patients who ultimately died, 58.21% of them were complicated with bacteremia ending in 34.33% of mortality. Early tracheostomy was beneficial in that less fluids were required for resuscitation. CONCLUSION: Burn infection was an important factor affecting the prognosis of inhalation injury. And inhalation injury and shock were major inducers of burn infection. Early application of wide spectrum antibiotics and shock management were helpful in lowering of burn infection rate. Early tracheostomy might be beneficial to burn shock management.

Anti-Bacterial Agents↗
PubMed2002

[Cloning of Ig Fab genes of patients with chronic B lymphocytic leukemia and sequences analysis of their variable regions].

OBJECTIVE: Sequences analysis of Ig variable regions from the peripheral blood mononuclear cells (PBMC) of patients with chronic B lymphocytic leukemia. METHODS: Total RNA was isolated from PBMC of patients with chronic B lymphocytic leukemia, oligo-dT-primed cDNA was synthesized from RNA. The cDNA was amplified by Taq DNA polymerase with a set of specific 5' primers corresponding to Ig FR1 and 3' primers corresponding to CH1 (C micro /C) or CL (Ckappa/Clambda), the PCR products of variable regions of Ig heavy (IgH) and light (IgL) chains were sequenced by ABI PRISM Dye terminator cycle sequencing ready reaction kit and ABI PRISM 310 Genetic Analyzer. The gene homology of variable regions of IgH and IgL chains was compared by using DNA tools 5.1 system and "the international immunogenetics database". RESULTS: Four light chains and 3 heavy chains were amplified from 4 and 3 patients respectively. Homology analysis of the sequences of 4 light chains and 3 heavy chains were performed by DNA tools system. The sequences of light chains are high homologous. And the sequences of heavy chains are quite different. The homologous analysis of the sequences of variable region by using "the international immunogenetics database" showed that the sequences were higher homologous to idiotype gene of some B lymphocytic leukemia. Four VL genes belong to human Ig Vkappa subgroup I, 2 of 3 VH genes belong to VH3 family and 1 belongs to VH5 family. CONCLUSION: Ig genes have idiotype and same disease may have same idiotype.

Base Sequence↗
PubMed2002

[Fusion expression of PLA2 gene from Lapemis hardwickii in E. coli].

The gene encoding PLA2(PLA2-9) from Lapemis hardwickii Gray venom was cloned to the 3' and of the thioredoxin gene (HP-trxA and trxA) in plasmid pthioHisC and pTRX to construct the pThioHisC-PLA2, and pTRX-PLA2 fusion expression vector. The fusion protein of PLA2 can be expressed in the two different systems induced by IPTG at 25 degrees C, but the expression level and the solubility of the fusion protein in pTRX were better than that in pThioHisC. The expressed product in the two systems were purified by immobilized metal-chelate affinity chromatography. The Trx-PLA2 fusion protein with over 85% purity was obtained and HP-Trx-PLA2 fusion protein can not be purified since it dose not exhibit affinity to the medium. So, the pTRX-PLA2 vector system was established for the large-scale expression and purification.

Animals↗
PubMed2002

[Effect of excessive Zn2+ and deficient Zn2+ on the expression of wild type-p53 mRNA in rat glicoma cells].

RT-PCR is applied to observe the effects of excessive and deficient Zn2+ on the expression of wild type-p53 (wt-p53) in rat glicoma cells. Rat glicoma cells in garithmic growth phase is treated with 0.3 mmol/L Zn2+ and 5 mumol/L TPEN respectively for 24 hours. Results show that the expression of wt-p53 of rat glicoma cells increased obviously in the deficient zinc group but does not increased in the excessive zinc group. These indicate that the expression of wt-p53 mRNA of rat glicoma cells is up-regulated by deficient zinc and inhibited by excessive zinc.

Animals↗
PubMed2002

[Determination of selenium in Kaoliang seed-skin by extraction FAAS].

This paper reports the determination of selenium by FAAS, extracted with APDC and MIBK, Being extracted and enriched, it not only overcomes the shortcomings, being difficult to determine selenium for the low efficiency of atomization, but also eliminates the disturbance in determination of selenium from the stabilizer Cu2+ and the other metal ions in the sample. The method was applied to the determination of selenium in the husk of Kaoliang and had a good effect. The method is simple and rapid with good precision and accuracy. The relative standard deviation is 4.18%. The recovery is 97.8%.

Edible Grain↗