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Feng Chen

Publications and source records attributed to Feng Chen.

At least 73 records · Page 4Linked to original sources
PubMed2006

Modulation of high alcohol drinking in the inbred Fawn-Hooded (FH/Wjd) rat strain: implications for treatment.

The Fawn-Hooded rat (FH/Wjd) is an inbred alcohol-preferring rat strain, unlike most of the other strains that were selectively bred for high alcohol intake and preference. It was chosen for study some 16 years ago because of a reported mutation that disrupted platelet serotonin function. Although the FH/Wjd rat has high alcohol intake (>5 g/kg/day) and preference (>65%), interbreeding with an alcohol-non-preferring inbred strain suggested that these measures are unrelated to the serotonin abnormality. Similarly, the exaggerated immobility of the FH/Wjd rats in the forced swim test did not correlate with the high alcohol intake. Many compounds have been tested in the FH/Wjd rats after both acute and chronic treatment and a substantial number of them have proved effective. However, as the case with opiate antagonists, tolerance to the effects of the drug can develop. An up-regulation of opioid receptors accompanied the chronic treatment and this mechanism may account for the development of tolerance. Tolerance to opiate antagonists has also been demonstrated in two of the selectively bred alcohol-preferring rat lines, but it is unknown whether this process may contribute to the relapses seen in individuals being treated with naltrexone. Other drugs that reliably decrease alcohol intake in the FH/Wjd rats include the 5-hydroxytryptamine-2A receptor antagonist, amperozide, the mGlu5 receptor antagonist 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP) and herbal derivatives such as ibogaine, St. John's wort and kudzu extract. Thus, studies in the FH/Wjd rat have led to the discovery of a wide variety of targets for the development of novel agents to treat alcoholism. The fact that several of these drugs were shown to reduce alcohol intake in some of the selectively bred alcohol-preferring rat lines and/or alcohol-preferring vervet monkeys increases our confidence that they are good candidates for further development.

Alcoholism↗
PubMed2006

The molecular mechanism of resistance to methotrexate in mouse methotrexate-resistant cells by cancer drug resistance and metabolism SuperArray.

Drug resistance is often a limiting factor in successful chemotherapy. Understanding of the molecular mechanism of resistance to methotrexate is important for optimal use as well as for the development of new drugs. Using standard cytogenetic techniques, double minutes (DMs) were detected in mouse methotrexate-resistant cell lines inducted in vitro in this study. Moreover, functional SuperArray, determining the regulation of gene expression corresponding to 96 genes involved in the metabolism of and the development of resistance to cancer drugs was used to study in detail the molecular mechanism of resistance to methotrexate. Significant higher expressions of many genes especially dhfr, mrp5, atm and p53 were detected in methotrexate-resistant cells than in normal mouse cells by SuperArray analysis and corresponding excessive expressions of DHFR, MRP5, ATM, and P53 proteins in methotrexate-resistant cells were also confirmed by Western blot analysis. The results in this study indicated that DHFR, MRP5, ATM, and P53 could play important roles in resistance to methotrexate and some of them would be new potential drug targets.

Animals↗
PubMed2006

Induction of multiple prophages from a marine bacterium: a genomic approach.

Approximately 70% of sequenced bacterial genomes contain prophage-like structures, yet little effort has been made to use this information to determine the functions of these elements. The recent genomic sequencing of the marine bacterium Silicibacter sp. strain TM1040 revealed five prophage-like elements in its genome. The genomes of these prophages (named prophages 1 to 5) are approximately 74, 30, 39, 36, and 15 kb long, respectively. To understand the function of these prophages, cultures of TM1040 were treated with mitomycin C to induce the production of viral particles. A significant increase in viral counts and a decrease in bacterial counts when treated with mitomycin C suggested that prophages were induced from TM1040. Transmission electron microscopy revealed one dominant type of siphovirus, while pulsed-field gel electrophoresis demonstrated two major DNA bands, equivalent to 35 and 75 kb, in the lysate. PCR amplification with primer sets specific to each prophage detected the presence of prophages 1, 3, and 4 in the viral lysate, suggesting that these prophages are inducible, but not necessarily to the same level, while prophages 2 and 5 are likely defective or non-mitomycin C-inducible phages. The combination of traditional phage assays and modern microbial genomics provides a quick and efficient way to investigate the functions and inducibility of prophages, particularly for a host harboring multiple prophages with similar sizes and morphological features.

Bacteriophages↗
PubMed2006

Diverse and unique picocyanobacteria in Chesapeake Bay, revealed by 16S-23S rRNA internal transcribed spacer sequences.

rRNA internal transcribed spacer phylogeny showed that Chesapeake Bay is populated with diverse Synechococcus strains, including members of the poorly studied marine cluster B. Marine cluster B prevailed in the upper bay, while marine cluster A was common in the lower bay. Interestingly, marine cluster B Synechococcus included phycocyanin- and phycoerythrin-rich strains.

Cyanobacteria↗
PubMed2006

Polymorphisms in the two helicases ERCC2/XPD and ERCC3/XPB of the transcription factor IIH complex and risk of lung cancer: a case-control analysis in a Chinese population.

The transcription factor IIH (TFIIH) helicases ERCC2/XPD and ERCC3/XPB are responsible for opening the DNA strand around the lesion site during nucleotide excision repair process. Genetic variants in these two genes may be markers for interindividual variability in DNA repair capacity and thus predisposition to cancer risk. In this case-control study of 1,010 incident lung cancer cases and 1,011 age and sex frequency-matched cancer-free controls in a Chinese population, we genotyped eight tagging polymorphisms of ERCC2 and ERCC3 using the high-throughput Taqman platform to determine their associations with risk of lung cancer. Although none of the eight polymorphisms was individually associated with lung cancer risk, we found that genetic variants in ERCC2 and ERCC3 jointly contributed to lung cancer risk in a dose-response manner. Compared with those with 0 to 1 "at-risk" locus, subjects carrying >1 at-risk loci were at increased risk for lung cancer [adjusted odds ratio (OR), 1.29; 95% confidence interval (95% CI), 0.98-1.70 for 2 at-risk loci; adjusted OR, 1.38; 95% CI, 1.02-1.85 for 3 at-risk loci; and adjusted OR, 1.51; 95% CI, 1.09-2.10 for > or =4 at-risk loci, respectively; P(trend) = 0.015]. This combined effect was slightly more evident in young subjects (<60 years), males, current smokers, and those with family history of cancer, particularly for histologic type of adenocarcinomas. No evidence for interaction was found. These findings indicate that these tagSNPs of the ERCC2 and ERCC3 along with their surrounding regions may serve as biomarkers of susceptibility to lung cancer, which warrant further validation by other population-based and phenotypic studies to determine the biological relevance of these tagSNPs.

Adenocarcinoma↗
PubMed2006

Characterization of a Cys329Gly mutation causing hereditary factor VII deficiency.

We have previously reported a homozygous Cys329Gly mutation in a Chinese patient with factor VII (FVII) deficiency. Others have found a heterozygous Cys329Gly mutation in the F7 gene from patients of three different pedigrees. However, none of the reports included the expression and characterization of the mutant FVII in vitro. To investigate the effect of Cys329Gly on FVII function, we carried out transient transfections of baby hamster kidney cells (BHK-21) with a mutant FVII construct and compared the results to those obtained using a wild-type FVII construct and vector control. The results demonstrate that the level of FVII:Ag secreted into the medium by transfected BHK-21 cells with mutant construct was not affected, but the coagulation activity of the mutant FVII was undetectable. We conclude that Cys329 is critical to FVII coagulation, and the replacement of cysteine 329 by glycine leads to the loss of coagulation activity in the patients, possibly the molecular basis for FVII deficiency in the patients.

Amino Acid Substitution↗
PubMed2006

AlphaB-crystallin is a novel oncoprotein that predicts poor clinical outcome in breast cancer.

Recent gene profiling studies have identified a new breast cancer subtype, the basal-like group, which expresses genes characteristic of basal epithelial cells and is associated with poor clinical outcomes. However, the genes responsible for the aggressive behavior observed in this group are largely unknown. Here we report that the small heat shock protein alpha-basic-crystallin (alphaB-crystallin) was commonly expressed in basal-like tumors and predicted poor survival in breast cancer patients independently of other prognostic markers. We also demonstrate that overexpression of alphaB-crystallin transformed immortalized human mammary epithelial cells (MECs). In 3D basement membrane culture, alphaB-crystallin overexpression induced luminal filling and other neoplastic-like changes in mammary acini, while silencing alphaB-crystallin by RNA interference inhibited these abnormalities. alphaB-Crystallin overexpression also induced EGF- and anchorage-independent growth, increased cell migration and invasion, and constitutively activated the MAPK kinase/ERK (MEK/ERK) pathway. Moreover, the transformed phenotype conferred by alphaB-crystallin was suppressed by MEK inhibitors. In addition, immortalized human MECs overexpressing alphaB-crystallin formed invasive mammary carcinomas in nude mice that recapitulated aspects of human basal-like breast tumors. Collectively, our results indicate that alphaB-crystallin is a novel oncoprotein expressed in basal-like breast carcinomas that independently predicts shorter survival. Our data also implicate the MEK/ERK pathway as a potential therapeutic target for these tumors.

Breast Neoplasms↗
PubMed2006

Accumulation of gamma-aminobutyric acid in rice germ using protease.

The accumulation of gamma-aminobutyric acid (GABA) in the rice germ by using protease was investigated. After the proteolytic hydrolysis of germ protein by trypsin, the amount of GABA reached about 2.26 g per 100 g of germ. This demonstrates that the GABA yield could be significantly increased by protease. Our method is efficient and safe for manufacturing health food enriched with GABA.

Food Handling↗
PubMed2006

Surveillance of viral contamination of invasive medical instruments in dentistry.

OBJECTIVE: To investigate the viral contamination of invasive medical instruments in dentistry and to provide health administrative institutions with surveillance data. METHODS: Sterilized samples were randomly collected from the department of dentistry to detect HBV-DNA, HCV-RNA, HIV-RNA and HBsAg. RESULTS: Of the invasive medical instruments that were sterilized with 2% glutaraldehyde, one of the samples was positive for HBV-DNA, and another sample was positive for HBsAg. CONCLUSION: Though massive virus contamination of invasive medical instruments in dentistry has been reduced to a low level, the occurrence of contamination still remains.

DNA, Viral↗
PubMed2006

Inactivation of the tumor suppressor Krüppel-like factor 6 (KLF6) by mutation or decreased expression in hepatocellular carcinomas.

BACKGROUND AND AIM: The Krüppel-like transcription factor KLF6 is a novel tumor-suppressor gene. It was inactivated in human prostate cancer and other tumors tissue, as the result of frequent mutation and loss of heterozygosity (LOH). However, there is no data reporting the levels of KLF6 both mRNA and protein in hepatocellular carcinomas (HCCs). We therefore detected mutations and expression of KLF6 in HCC tissues and further observed the effect of it on cell growth in HCC cell lines. METHODS: We analyzed the exon-2 of KLF6 gene by direct DNA sequencing, and detected the expression of KLF6 by RT-PCR and Western blot in 23 HCC tissues and corresponding nontumorous tissues. Loss of growth suppressive effect of the HCC-derived KLF6 mutant was characterized by in vitro growth curves plotted, flow cytometry and Western blotting. RESULTS: KLF6 mutations were found in 2 of 23 HCC tissues and one of mutations was missense. Expression of KLF6 mRNA or protein was down-regulated in 8 (34.7%) or 9 (39.1%) of 23 HCC tissues. Wild-type KLF6 (wtKLF6) inhibited cellular proliferation and prolonged G1-S transition by inducing the expression of p21WAF1 following stable transfection into cultured HepG2 cells, but tumor-derived KLF6 mutant (mKLF6) had no effects. CONCLUSION: Our findings suggest that KLF6 may be involved in pathogenesis of HCC.

Blotting, Western↗
PubMed2006

Simultaneous amplification of 5' and 3' cDNA ends based on template-switching effect and inverse PCR.

A new approach for simultaneously amplifying the 5' and 3' ends of a desired cDNA is described. The method combines the template-switching effect with inverse PCR, which generates the flanking 5' and 3' regions of a certain cDNA with very low or no background. It requires only minimal amounts of total RNA for the synthesis of first-strand cDNA, while the same cDNA can be used to amplify flanking sequences of any cDNA species present in the sample. This method is reliable and easy to perform, which is very useful for isolating cDNA species of rare transcripts.

Base Sequence↗
PubMed2006

[SHENG Xie-sun's experiences in application of the four important points of the Governor Vessel].

SHENG Xie-sun has unique experiences in location and needling methods of Baihui (GV 20), Dazhui (GV 14), Lingtai (GV 10) and Mingmen (GV 4) on the Governor Vessel. He holds that these are four important points on the Governor Vessel. Especially, he has own unique method in location of Baihui (GV 20) and Dazhui (GV 14). After correct location of Baihui (GV 20), the various points on all sides can be located according to the different distance; for location of Dazhui (GV 14), firstly Jugu (LI 16) on the bilateral shoulders are located accurately, and then Dazhui (GV 14) is located below the spinous process on the horizontal line between the two points. Point-through-point needling method and needle tip qi-inducing method are used. And he is good at application of moxibustion for treatment of difficult and complicated diseases and visceral diseases, and attains obvious clinical therapeutic effect.

Acupuncture Points↗
PubMed2006

[Mutations of the tumor suppressor Kruppel-like factor 6 (KLF6) gene in hepatocellular carcinoma and its effect of growth suppression on human hepatocellular carcinoma cell line HepG2].

OBJECTIVE: To explore the mutated KLF6 gene in hepatocellular carcinoma (HCC) and to characterize its behavior in human hepatocellular carcinoma cell line HepG2. METHODS: We analyzed the DNA isolated from 23 hepatocellular carcinoma tissues and their adjacent nontumor tissues by polymerase chain reaction (PCR). Direct sequencing was used to establish the incidence of mutation in exon2 of the KLF6 gene. Loss of growth suppressive function of the HCC-derived KLF6 mutants was characterized by in vitro analyzing alteration of cell cycle and MTT assay. Expression of p21WAF1, a possible downstream gene of KLF6, was detected in human hepatocellular carcinoma cell line HepG2 transiently transfected with KLF6 genes. RESULTS: Mutations of KLF6 were found in 2 of the 23 (8.7%) hepatocellular carcinomas. The two mutations were located in the transactivation domain and one of them resulted in single amino acid substitution of TGG (W) by GGG (G) at codon 162. Unlike the wild-type KLF6, cancer-derived KLF6 mutants neither suppressed growth nor induced p21WAF1 following transfection into culture cells. CONCLUSIONS: Mutations of the KLF6 gene may play a role in the pathogenesis of HCC, but are not the dominating mechanism resulting in inactivation of KLF6 functions. KLF6 suppresses hepatocellular carcinoma cell proliferation partly through upregulating expression of the p21WAF1 gene.

Base Sequence↗
PubMed2006

[Methods applied to muscle fatigue assessment using surface myoelectric signals].

Surface myoelectric signal analysis has proved effective for assessing the electrical manifestations of localized muscle fatigue. In the past, the analysis of muscle fatigue was restricted to isometric, constant force contractions due to the limitation of signal processing technique. The development and recent availability of spectral estimation techniques specifically designed for nonstationary signal analysis have made it possible to extend the employment of muscle fatigue assessment to dynamic contractions, thus opening new application fields such as ergonomics rehabilitation and sports medicine. This paper reviews the current study achievements of using surface myoelectric signals in muscle fatigue assessment, particularly in that during dynamic contractions. The conclusions provide theoretical bases for encouraging further studies on the mechanisms of muscle fatigue.

Electromyography↗
PubMed2006

[Estimation on gene-environment interaction in the partial case-control study].

OBJECTIVE: To introduce the approaches for estimating gene-environment interaction based on partial case-control studies. METHODS: The effects of logistic model and log-linear model for estimating the main effects and gene-environment interaction effect were estimated by means of maximum likelihood methods in traditional case-control studies, case-only studies and partial case-control studies, respectively. An example was also illustrated. RESULTS: In traditional case-control study with complete data, the results of logistic model and log-linear model were equivalent. In case-only study without any information about controls, the logistic model can also efficiently estimate gene-environment interaction. In partial case-control study, environmental information was collected from all of the cases and controls, while genetic information was only collected from cases. For this case-control study with incomplete data, a suitable parameterized log-linear model could simultaneously and efficiently estimate the main effect of environment and gene-environment interaction, whereas the logistic model could not. CONCLUSION: For a partial case-control study, log-linear model could estimate not only the main effect of environment but also gene-environment interaction. If genotype and exposure were independent, estimators from partial case-control were as precisely as those from complete-data case-control studies.

Case-Control Studies↗
PubMed2006

[Introduction on "case-sibling control design"].

OBJECTIVE: To introduce the design and statistical methods of case-sibling control design and to analyze the published data. METHODS: Data from an association study between the coronary heart disease and methylenetetrahydrofolate reductase gene C677T polymorphism was analyzed by the sib transmission/disequibrium test (s-TDT) and the sibship disequilibrium (SDT) methods. RESULTS: Using s-TDT method, Z value was 0.27 with P > 0.05. The result of SDT method showed that chi-square was 0.31 with 1 df, P > 0.05. All results suggested that neither s-TDT nor SDT showed significant difference between the transmitted and untransmitted methylenetetrahydrofolate reductase gene C677T allele distributions. CONCLUSION: Case-sibling control design might avoid population stratification by using siblings as controls thus might be used to test association and linkage between genes and disease.

Case-Control Studies↗
PubMed2006

[Effect of nitric oxide and nitric oxide synthase on sensorineural hearing loss secondary to secretory otitis media].

OBJECTIVE: To evaluate the effect of nitric oxide synthase (NOS) and nitric oxide(NO) on sensorineural hearing loss (SNHL) secondary to secretory otitis media (SOM). METHOD: Samples of middle ear effusion were collected at the time of tympanocentesis from 16 cases of SOM with SNHL(group A) and 16 cases of SOM without SNHL(group B). And the concentration of NO and NOS activity in middle ear effusion were detected by colorimetric assay (Griess method). RESULT: The concentration of NO in group A (181.19 +/- 44.31) micromol/L was significantly higher than that in group B (137.00 +/- 40.67) micromol/L (P < 0.01). The NOS activity in group A (97.69 +/- 29.62)U was also significantly higher than that in group B (75.50 +/- 26.99)U (P < 0.05). CONCLUSION: Excess generation of NO in middle ear effusion which synthesized by NOS may hurt inner ear directly by its cytotoxic action or enhance local inflammatory reaction with other inflammatory factors. This study suggests that NO play a significant role in the process and pathogenesis of SNHL secondary to SOM.

Adult↗