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Biomedical subjects

Wen Chen

Publications and source records attributed to Wen Chen.

At least 73 records · Page 4Linked to original sources
PubMed2003

Proteomic comparison between human young and old brains by two-dimensional gel electrophoresis and identification of proteins.

To investigate molecular mechanisms of human brain aging, brain proteins were isolated from postmortem human young and old brains and profiled by two-dimensional gel electrophoresis (2-DE). With the help of special software, five down-regulated protein spots in two-dimensional gel electrophoresis gels of old brains were found compared with young brains, four of which was identified as a protein similar to peroxiredoxin 2 (accession-numbered as gi | 13631440), two of stathmin (phosphoprotein p19) and apolipoprotein A-I precursor (apo-AI) by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Eight common proteins, whose expressions were not altered between young and old brains, were also identified. The possible relevance of changes was analyzed. This study shows that the contribution of proteomics could be valuable in experimental gerontology field.

Adult↗
PubMed2003

Human mammary epithelial cell transformation through the activation of phosphatidylinositol 3-kinase.

Recent studies have demonstrated that introduction of hTERT in combination with SV40 large T antigen (LT), small t antigen (st), and H-rasV12 suffices to transform many primary human cells. In human mammary epithelial cells (HMECs) expressing elevated c-Myc, activated H-Ras is dispensable for anchorage-independent growth. Using this system, we show that st activates the PI3K pathway and that constitutive PI3K signaling substitutes for st in transformation. Moreover, using constitutively active versions of Akt1 and Rac1, we show that these downstream pathways of PI3K synergize to achieve anchorage-independent growth. At lower levels of c-myc expression, activated PI3K also replaces st to complement H-rasV12 and LT and confers both soft agar growth and tumorigenicity. However, elevated c-myc expression cannot replace H-rasV12 for tumorigenesis. These observations begin to define the pathways perturbed during the transformation of HMECs.

Agar↗
PubMed2003

Abolition of cyclin-dependent kinase inhibitor p16Ink4a and p21Cip1/Waf1 functions permits Ras-induced anchorage-independent growth in telomerase-immortalized human fibroblasts.

Human cells are more resistant to both immortalization and malignant transformation than rodent cells. Recent studies have established the basic genetic requirements for the transformation of human cells, but much of this work relied on the expression of transforming proteins derived from DNA tumor viruses. We constructed an isogenic panel of human fibroblast cell lines using a combination of gene targeting and ectopic expression of dominantly acting mutants of cellular genes. Abolition of p21(Cip1/Waf1) and p16(Ink4a) functions prevented oncogenically activated Ras from inducing growth arrest and was sufficient for limited anchorage-independent growth but not tumorigenesis. Deletion of the tumor suppressor p53 combined with abolition of p16(Ink4a) function failed to mimic the introduction of simian virus 40 large T antigen, indicating that large T antigen may target additional cellular functions. Ha-Ras and Myc cooperated only to a limited extent, but in the absence of Ras, Myc cooperated strongly with the simian virus 40 small t antigen to elicit aggressive anchorage-independent growth. The experiments reported here further define specific components of human transformation pathways.

Antigens, Polyomavirus Transforming↗
PubMed2003

[Autologous buccal mucosal graft for urethral reconstruction].

OBJECTIVE: To search for a new method for urethra reconstruction using autologous buccal mucosal graft while lacking of local skin. METHODS: Since 1998, a total of 25 patients with complex hypospadias have been treated using buccal mucosal grafts for urethral reconstruction. The reconstructed urethra was anastomosed with the meatus half year later. RESULTS: All the reconstructed urethra survived without contracture or stricture except one infection, which healed with no adverse consequence. CONCLUSION: The key points for operation success is rich capillary network, thick epidermis and thin lamina propria of the buccal mucosa. Buccal mucosa is an excellent tissue for urethral reconstruction.

Capillaries↗
PubMed2003

[The effect of telomerase inhibitors on oral squamous carcinoma cells].

OBJECTIVE: To study the potential anti-tumor effect of telomerase inhibitors. METHODS: Human oral squamous carcinoma cell line KB was selected as target cell. The effects of 3'-azido-3'-deoxythymidine (AZT) and human antisense phosphorothioate (AS-ONS) for telomerase template on KB cell line were investigated. The cytotoxic effect of AZT and AS-ONS on tumor cells was quantified using MTT colorimetric assay. Assay of 3H-TdR incorporation was undertaken to measure the cell proliferation. The changes of telomerase activity after treatment was detected and quantified by telomeric repeat amplification protocol (TRAP) semi-quantitative analysis. The Flow Cytometry was used to detect apoptosis and measure cell cycle. RESULTS: Both AZT and AS-ONS inhibited the growth of KB cell line in a certain range of concentrations, and meanwhile the telomerase activity was reduced after treatment. In addition, both AZT and AS-ONS can induce apoptosis and arrest G1 phase of cell cycle. CONCLUSION: The results obtained above indicated that AZT and AS-ONS could be potentially used as an anti-oral carcinoma agent or an auxiliary treatment for cancer. Those inhibitory effects might be partially due to the induction of apoptosis and the prolongation of cell cycle.

Antineoplastic Agents↗
PubMed2003

Heregulin targets gamma-catenin to the nucleolus by a mechanism dependent on the DF3/MUC1 oncoprotein.

The DF3/MUC1 transmembrane oncoprotein is aberrantly overexpressed in most human breast carcinomas and interacts with the Wnt effector gamma-catenin. Here, we demonstrate that MUC1 associates constitutively with ErbB2 in human breast cancer cells and that treatment with heregulin/neuregulin-1 (HRG) increases the formation of MUC1-ErbB2 complexes. The importance of the MUC1-ErbB2 interaction is supported by the demonstration that HRG induces binding of MUC1 and gamma-catenin and targeting of the MUC1-gamma-catenin complex to the nucleolus. Significantly, nucleolar localization of gamma-catenin in response to HRG is dependent on MUC1 expression. Moreover, mutation of a RRK motif in the MUC1 cytoplasmic domain abrogates HRG-induced nucleolar localization of MUC1 and gamma-catenin. In concert with these results, we show nucleolar localization of MUC1 and gamma-catenin in human breast carcinomas but not in normal mammary ductal epithelium. These findings demonstrate that MUC1 functions in cross talk between ErbB2 and Wnt pathways by acting as a shuttle for HRG-induced nucleolar targeting of gamma-catenin.

Active Transport, Cell Nucleus↗
PubMed2003

[Oral mucosa graft combined with a local turn-over flap for urethral reconstruction in various hypospadias].

OBJECTIVE: Explore a good method for treating various hypospadias. METHODS: Oral mucosa graft combined with a local turn-over flap was used for urethral reconstruction in 39 cases of hypospadias. RESULTS: All the 39 cases were cured successfully in one stage, and satisfactory penile configuration obtained. CONCLUSION: This operation solved the problem of tissue scarcity in urethral reconstruction. It made use of the merits of different materials and avoided the disadvantage of a single tissue. It is good for treating various hypospadias and worthy of popularization.

Humans↗
PubMed2003

[Effects of daidzein on sperm quality, testis gain and testosterone in mice].

OBJECTIVE: To evaluate the effects of daidzein on sperm quality of male mice. METHODS: Three different doses of daidzein were supplemented to pubertal male mice for 21 days(5 mg/kg, 100 mg/kg, 1,000 mg/kg ration). The viability of sperm was determined by eosin-Y, the acrosome was observed by Wright-Giemsa staining, and the testosterone was measured by radioimmunoassay. RESULTS: Daidzein at the dose of 5 mg/kg ration significantly increased serum testosterone levels (P < 0.01), prompted testis gain (P < 0.05), and improved spermatozoa quality. Daidzein at dose of 1,000 mg/kg ration could inhibit the secretion of serum testosterone (P < 0.01), without significant variation in spermatozoa quality. Daidzein at dose of 100 mg/kg ration did not significantly affect sperm quality and other index. CONCLUSIONS: Daidzein can affect sperm quality and in dosage-dependant ways.

Animals↗
PubMed2003

[RNA-based transgene silencing: mechanism and applications].

RNA-based transgene silencing is a phenomenon that endogenous and exogenous mRNAs are degraded specifically directed by double-stranded RNA. Here we review the recent advances on its mechanism and summarize related proteins and expatiate their functions. Furthermore,we introduce the enormous potential of dsRNA as a tool in functional genomics research and practical biotechnology.

English Abstract↗
PubMed2002

[Influence of high-frequency electric surgical knife on healing of abdominal incision, experimental and clinical studies].

OBJECTIVE: To study the influence of high-frequency electric surgical knife on abdominal incision healing. METHODS: Two hundred and forty Wistar rats were randomly divided into two groups of 120 rats to undergo abdominal incision by high-frequency electric knife or common lancet respectively. Each of these two groups was redivided into four subgroups that were injected hypodermically with 0.2 ml of quantitative mixture of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa at the concentrations of 0.24 x 10(2) bacteria (10(2) group), 4.49 x 10(4) bacteria (10(5) group), and 4.11 x 10(7) bacteria (10(8) group) respectively, and normal saline of the same volume (10(0) group). Eight days after the operation, the rats were killed. The infection rate of the operational wound was observed and the tissues around the wounds were examined pathologically. On the basis of the animal experiment, 220 patients undergoing abdominal operation above type II were randomly allocated into one of following three groups: high-frequency electric knife (EK) group (93 cases, high-frequency electric knife was used to cut the abdominal tissues and electro-coagulation was used for hemostasis), electro-coagulation (EC) group (55 cases, the abdominal tissues were cut with common lancet and electro-coagulation was used for hemostasis) and control group (72 cases, common lancet and silk thread suture were used). The healing of wound was observed after operation. RESULTS: Four rats died of anesthetic accident; the other 236 rats were killed 8 days after. The wound infection rates were 23.33% and 6.60% in the experimental 10(0) group and the control 10(0) group respectively (chi(2) = 3.28, P > 0.05); 37.04% and 13.33% in the experimental 10(2) group and the control 10(2) group respectively (chi(2) = 4.31, P > 0.05), 50.00% and 24.14% in the experimental 10(5) group and the control 10(5) group respectively (chi(2) = 4.22, P > 0.05); and 63.33% and 36.67% in the experimental 10(8) group and the control 10(8) group respectively (chi(2) = 4.27, P > 0.05). Clinical observation showed a delayed wound healing rate of 17.20% (16 cases) in EK group, 16.36% (11 cases) in EC group, and 2.86% (2 cases) in the control group. There was a statistically significant difference in delayed wound healing rate between the EK and control groups (chi(2) = 8.57, P < 0.01) and between the EC and control groups (chi(2) = 5.66, P < 0.05). However, no significant difference in the delayed wound healing rate was seen between the EK and EC groups (chi(2) = 0.017, P > 0.05). CONCLUSION: High-frequency electric knife remarkably delays the healing of abdominal incision. Its application should be minimized so as to reduce the possibility of postoperative complications.

Abdomen↗
PubMed2002

Comparative proteome analysis of human temporal cortex lobes by two-dimensional electrophoresis and identification of selected common proteins.

Human brain proteins were isolated from left and right temporal cortex lobes at the age of 73, 23, 84 years and separated by two-dimensional gel electrophoresis (2-DE). 2-DE was carried out with an immobilized pH gradient strip in the first dimension and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the second dimension. Over 800 polypeptide spots were resolved with a silver-staining protocol by computerized 2-D gel analsis. Seven of the polypeptide spots were evidently distinguishable between human left and right temporal lobes. Four of the polypeptide spots were larger and three were smaller in human right temporal lobe. One of these three protein spots that have descendent expression in human right temporal lobe was identified as carbonyl reductase (NADPH) 1 by MALDI-TOF MS. Thirty-three common spots were identified by ESI-MS/MALDI-TOF MS/Edman sequencing and a protein database search. These identified proteins include some important enzymes and regulating proteins.

Amino Acid Sequence↗
PubMed2002

Role of polyphosphate kinase in biofilm formation by Porphyromonas gingivalis.

In order to assess the role of polyphosphate kinase (PPK) in the physiology of Porphyromonas gingivalis, a ppk gene mutant, CW120, was constructed and characterized. P. gingivalis was demonstrated to synthesize short-chain polyphosphate (polyP) but not long-chain polyP. CW120 failed to survive in the stationary phase as well as the parental cell did, and it was attenuated in biofilm formation on polyvinylchloride and glass surfaces. Furthermore, the complementation by insertion of an intact copy of the ppk gene into the mutant CW120 restored its biofilm formation and stationary-phase survival. These results suggest that PPK may be important for incorporation of these organisms into subgingival plaque in the human oral cavity.

Biofilms↗
PubMed2002

Toxicity, persistence, and efficacy of indoxacarb on cabbage looper (Lepidoptera: Noctuidae) on cabbage.

Toxicity of indoxacarb was bioassayed against eggs and young (first and second instars) and older larvae (third and fourth instars) of cabbage looper, Trichoplusia ni (Hübner), on cabbage (Brassicae oleracea variety capitata L.), and persistence of field-aged leaf residues of indoxacarb was bioassayed with second and third instars of T. ni on cabbage. Efficacies of indoxacarb and several other newer insecticides to T. ni were tested under field conditions for two seasons in south Texas. LC50 and LC90 values for T. ni eggs were relatively high, indicating that indoxacarb has little ovicidal effects on T. ni eggs. Indoxacarb was highly toxic to T. ni larvae, having low LC50 and LC90 values. Bioassays of field-aged leaf residues of indoxacarb tested in the spring of 1998 (0-, 3-, 5-, and 12-d-old residues) and the fall of 2000 (0-, 3-, 5-, 7-, 9-, and 13-d-old residues) indicated that ingesting indoxacarb was highly toxic to the second and third instars of T. ni, giving 100% mortality for the second instars at 2 d after exposure, and 100% mortality for third instars at 5 d after exposure. Two trials conducted under field conditions show that indoxacarb at 0.072 g (AI) /ha rate was effective against T. ni in cabbage, providing marketable cabbage with three applications per season. In addition, indoxacarb was as effective as spinosad and chlorfenapyr and significantly more effective than tebufenozide and emamectin benzoate.

Animals↗
PubMed2002

[Analysis of risk factors for cervical cancer in Xiangyuan County, Shanxi Province].

OBJECTIVES: To investigate the risk factors for cervical cancer in the areas of high incidence, and provide evidence for current intervention of cervical cancer. METHODS: In the areas of Xiangyuan County, Shanxi Provicne with high incidence of cervical cancer, 1 997 women were interviewed using a questionnaire, including baseline information, menstrual, marital and pregnancy histories, sexual behavior, health habits, contraception, medical history and family history of cancer, etc., after its screening with six kinds of methods. All subjects, including 84 cases with pathological diagnosis of greater than cINI, and 1 784 cases with pathological diagnosis of normal, were tested for high-risk HPV. RESULTS: The overall rates of HPV infection were 20.8% (415/1 997) in high-risk subjects, 97.7% and 14.2% in the cases and control groups, respectively. Univariate analysis showed that risk factors with statistical significance included high-risk HPV infection, age at first sexual intercourse, history of pregnancy and abortion, the number of sexual partners and family history of cancer. Analysis with non-conditional logistic regression model revealed high-risk HPV infection, multiple sexual partners and family history of cancer associated obviously with occurrence of cervical cancer. In addition, there was significantly positive relationship between HPV infection, which increased with the number of sexual partners, and extramarital sexual activity both in males or females. CONCLUSIONS: The main risk factor for cervical cancer in this region was high-risk HPV infection, which related to sexual behavior, hygienic habits during menstruation and puerperium. It was particularly important to detect and treat precancerous lesions and to implement behavior modification. In addition, further research on genetic susceptibility was suggested.

Abortion, Induced↗
PubMed2002

[Repair of cartilage defect of knee joints with free periosteal autograft].

OBJECTIVE: To investigate the clinical application of periosteal autograft in repair of cartilage defect caused by osteoarthritis of knee. METHODS: From 1996 to 1999, 36 knees of cartilage defect of knee joint in 28 cases were treated. In the operation, the cracked degenerative cartilage was removed before free periosteum from tibia was transplanted to repair the defect, and the meniscuses in 8 kness of the 36 knees were reconstructed. After operation, early continuous passive movement was adopted for 4 weeks, and 8 knees with reconstruction of the meniscus were immobilized by plaster splint for 7 days after operation and before passive movement. All of the cases were followed up for 1 to 4 years before clinical evaluation in symptoms, signs and radiological findings. RESULTS: The general satisfactory rate was 86.1%, in which the function was excellent in 22 knees and good in 9 knees. CONCLUSION: The periosteal autograft is a good choice for repairing cartilage defect due to osteoarthritis, with a satisfactory outcome in the short term.

Cartilage, Articular↗
PubMed2002

[Development of APSIM (agricultural production systems simulator) and its application].

Soil-crop simulator model is an effective tool for providing decision on agricultural management. APSIM (Agricultural Production Systems Simulator) was developed to simulate the biophysical process in farming system, and particularly in the economic and ecological features of the systems under climatic risk. The current literatures revealed that APSIM could be applied in wide zone, including temperate continental, temperate maritime, sub-tropic and arid climate, and Mediterranean climates, with the soil type of clay, duplex soil, vertisol, silt sandy, silt loam and silt clay loam. More than 20 crops have been simulated well. APSIM is powerful on describing crop structure, crop sequence, yield prediction, and quality control as well as erosion estimation under different planting pattern.

China↗