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Biomedical subjects

Feng Gao

Publications and source records attributed to Feng Gao.

At least 163 records · Page 9Linked to original sources
PubMed2005

Amplification and cloning of near full-length HIV-2 genomes.

The genomes of human immunodeficiency virus type 2 (HIV-2), like those of HIV-1, are not only extremely variable but are also highly recombinogenic. Determination of subtypes based on partial genomes cannot predict the subtype classification of other regions of the genome owing to the frequent occurrence of recombinant genomes among subtypes. To fully understand the genetic variation and evolution of HIV-2s, full-length viral genomes need to be obtained for genetic analysis. Full-length HIV-2 genomes can also be used as infectious clones to study viral biological characteristics and as reference sequences for phylogenetic analysis. More important, all genes in the obtained genomes can be cloned into expression vectors to produce proteins that can be used as antigens for diagnostic reagents or as immunogens for vaccine development. The long-range polymerase chain reaction technique has recently become a more preferred method than the lambda phage cloning method to obtain near-full-length HIV-2 genomes.

Cloning, Molecular↗
PubMed2005

[Mutation, loss of heterozygosity, and expression of tumor suppressor gene ING1 in sporadic colorectal carcinoma].

BACKGROUND & OBJECTIVE: Inhibitor of growth 1 (ING(1)) gene has been identified as a novel tumor suppressor gene. Its over-expression can inhibit cell growth, and induce cell apoptosis. This study was to explore the effect and significance of ING(1) gene in occurrence and progression of sporadic colorectal cancer. METHODS: The expression, mutation, and loss of heterozygosity (LOH) of ING(1) gene in 46 specimens of sporadic colorectal cancer tissues and adjuvant normal mucous membrane tissues were detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), PCR-single strain conformation polymorphism (PCR-SSCP), and microsatellite markers, respectively. RESULTS: (1)The average ratios of light density of p33/ING(1) mRNA, and p47/ING(1) mRNA in the cancerous tissues were significantly lower than those in normal tissues (0.52 vs. 1.28, P < 0.01; 0.51 vs. 1.21, P < 0.01). Difference between the 2 mRNA splices was not significant in the matched tissues (P > 0.05). (2) The average ratios of light density of p33/ING(1) mRNA, and p47/ING(1) mRNA in the cancerous tissues of Dukes' C, D stage were significantly lower than those in cancerous tissues of Dukes' A, B stage (0.38 vs. 0.65, P < 0.01; 0.40 vs. 0.63, P < 0.01). (3) Of the 46 cases, no mutation of ING(1) gene was detected, only 5 (10.9%)cases of LOH were found. CONCLUSIONS: Abnormal alteration of ING(1) gene is rare in sporadic colorectal cancer. Its down-regulation may happen in transcription or post-transcription, and correlates tightly with the occurrence and progression of sporadic colorectal cancer.

Adult↗
PubMed2005

[Effect of tetrandrine combined with Droloxifen on the expression of bcr/abl of K562 at both mRNA and protein levels].

To observe the effect of Tetrandrine (tet) combined with Droloxifen (DRL) on the expression of bcr/abl mRNA and P(210) BCR/ABL protein of K562 cell line, after K562 cells were cultured in the medium containing Tet (1 micromol/L), DRL (5 micromol/L) separately or in their combination for some time, the changes of bcr/abl mRNA and protein expression were detected by RT-PCR and Western blot respectively. The results showed that the application of single drug of Tet or DRL had no effect on bcr/abl mRNA and BCR/ABL protein expression in K562 cell line. However, Tet in combination with DRL began to downregulate bcr/abl mRNA and P(210) BCR/ABL expression of K562 cells at 48 h and 72 h, respectively. It is concluded that tetrandrine in combination with Droloxifen can downregulate the expression of bcr/abl mRNA and P(210) BCR/ABL protein and the combination may be involved in the mechanism underlying the reverse effects on multidrug resistance in leukemia.

Antineoplastic Agents↗
PubMed2005

[Protective effect of SNMC on mice with fulminant liver failure].

OBJECTIVE: To investigate the protective effect of stronger neo-minophagen C (SNMC) on fulminant liver failure (FLF). METHODS: D-Gal N and LPS were injected once into the abdominal cavity of rats to establish an experimental model of FLF. The level of plasma ALT, Alb, TBil, TNFalpha, NO, ET-1, IL-6 and liver histopathology of the rats were examined. RESULTS: In the D-Gal N and LPS model of FLF, there was an obvious decline of plasma TNFalpha (F = 52.84), NO (F = 15.81), ET-1 (F = 15.68), IL-6 (F = 15.32) and there was less hepatic tissue damage in SNMC-treated groups using different doses (high dose, medium dose, low dose) and at different times (pre-protection, simultaneous protection, post-protection) compared with those not treated with SNMC. These results indicated that SNMC could be used to treat FLF. It was better to use a low dose of SNMC and use it at the same time as inducing the FLF. There were no differences in the results of those treated with SNMC of different dosages and treated at different times. CONCLUSION: SNMC can decrease the mortality of FLF by preventing hepatocyte apoptosis induced by D-Gal N and LPS and inhibit liver inflammation caused by all kinds of factors.

Animals↗
PubMed2005

[Preparation and fluorescence study of anthracene, perylene and 1-aminoanthraquinone colloids].

Anthracene, perylene and 1-aminoanthraquinone colloids have been prepared by reprecipitation method. In comparison with the fluorescence emission spectra of colloids and molecules (in acetone solution), it was indicated that collids fluorescence spectra are red-shifted and easy emission. Base on the fluorescence emission and molecular structure theory, the authors conclude that these molecules overlap when they form particles. At the same time they are planar molecules. This results in the strong stacking electronic properties. So fluorescence excitation and emission become easy.

Acetone↗
PubMed2005

[Effect of different tidal volume ventilation on rat bronchial and alveolar epithelial cell apoptosis].

OBJECTIVE: To investigate the changes in bronchial and alveolar epithelial cell apoptosis after mechanical ventilation with different tidal volumes and explore the mechanism and significance of cell apoptosis in ventilation-induced lung injury. METHODS: Thirty healthy male Sprague-Dawley rats were randomly divided into groups A, B and C to receive tracheotomy under anesthesia for ventilation with different tidal volumes (VT) for 4 h (VT of 10 ml/kg in group A, 20 ml/kg in group B and 40 ml/kg in group C). Lung histopathology was assessed after the ventilation and compared between the 3 groups. The severity of lung injury and bronchial epithelial edema was evaluated, and the extent and location of cell apoptosis in the bronchus and lung tissues were studied by transferase d-UTP end-labeling (TUNEL) assay and immunohistochemistry. RESULTS: After mechanical ventilation for 4 h, lung injury and bronchial epithelial edema increased with the increment of VT. By TUNEL assay, the apoptosis index of both alveolar and bronchial epithelial cells was found to increase with VT. Immunohistochemical study identified enhanced caspase-3 expression in the cytoplasm and nuclei of airway and alveolar epithelial cells and vascular endothelial cells in rats with high VT ventilation, and the enhancement was especially obvious in the bronchial epithelial cells. CONCLUSION: Mechanical ventilation with different VTs causes consistent changes in histopathology, cell apoptosis and caspase-3 expression in rats, which support the presumption that cell apoptosis plays an important role in the pathogenesis of high VT ventilation-induced lung injury.

Animals↗
PubMed2005

[Clinical analysis of anorectal malignant melanoma].

OBJECTIVE: To summarize the clinicopathological characteristics of primary anorectal malignant melanoma (AMM). METHODS: Clinical data of nine patients with AMM were reviewed retrospectively from January 1999 to March 2005. RESULTS: Anorectal malignant melanoma had a female predominance. The average age was 56 years old and average course of disease was 5.8 months. The onset of symptom was hematochezia, then anus prolapses. 94.7% of patients had AMM within 5 cm from anus margin; the average tumor size was (3.3+/- 2.1) cm. The polyp and ulcer were most common types. More than a half (54.5%) of the tumor was movable, 19.1% smooth surfaced, 6.6% soft textured. Synchronous metastasis was found in 14.0% of the patients, the first common metastasis was found in liver, the secondary was superficial inguinal lymph node metastasis. Half of the patients were misdiagnosed,and over 50% of patients were misdiagnosed as benign disease. Mile's operation was performed in most of patients (63%), while anal resection was performed in 30% of the patients. CONCLUSIONS: Anorectal malignant melanoma is often misdiagnosed,surgical procedure is the first choice for patients with AMM.

Adult↗
PubMed2005

Relationship of ovarian neoplasms and body mass index.

OBJECTIVE: To describe the distribution of benign and malignant ovarian neoplasms among overweight and obese women. STUDY DESIGN: A review of patients who presented with a preoperative diagnosis of a pelvic mass between 1996 and 2001 was performed; 1,096 patients were identified. Patients were stratified by body mass index into 3 groups: normal weight, overweight and obese. The pathologic findings in the 3 groups were compared. RESULTS: Complete follow-up was available on 668 patients. Overall, 248 patients were obese, 176 were overweight, and 244 had a normal body mass index. A significant difference existed in the pathologic findings in the 3 groups (p = 0.049). Women with normal body mass indices were more likely to have malignant ovarian tumors (35.2%) than were the overweight (23.9%) and obese (25.8%) women. Conversely, borderline ovarian tumors were less frequent in women with body mass indices of <25 (5.7%) than in the overweight (13.1%) and obese (10.9%) patients. Benign ovarian neoplasms occurred in 20-25% of the women. CONCLUSION: Significant differences exist in the distribution of ovarian neoplasms among women with different body mass indices. Obese women are more likely to have ovarian tumors of low malignant potential, while women with normal body mass indices more commonly have invasive ovarian tumors. Body mass index may be an important factor in preoperative counseling and risk assessment.

Adolescent↗
PubMed2005

[Highly sensitive spectrofluorimetric determination of trace amounts of chromium (VI) with mono[6-o-(4-aminobenzoic acid)]-beta-cyclodextrin].

A novel fluorescence probe, mono[6-o-(4-aminobenzoic acid)]-beta-cyclodextrin(ACD), was synthesized, and a new sensitive fluorescence identification reaction was studied based on the reaction of Cr2O7(2-) with compound ACD in NaAc-HAc buffer medium at pH 4.90. Under optimal conditions the determination limit was 1.26 microg x L(-1). The linear range was 5.20-1040 microg x L(-1). This method has been applied to the determination of trace amounts of chromium (VI) in electroplating liquor, electroplating waste water with satisfactory results.

Chromium↗
PubMed2005

[Effect of losartan on expression of Janus kinase 2 and signal transducer and activator of transcription 3 in glomeruli of diabetic rats].

OBJECTIVE: To investigate the effects of losartan on Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 in glomeruli of diabetic rats. METHODS: Sixty Wistar male rats were randomly divided into control group (n=20), diabetes group (n=20), and losartan treatment group (n=20). Diabetes was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). Losartan (10 mg/kg) was administered daily by gavage from the day following the induction of diabetes. The animals were sacrificed in the weeks 2 and 4 after STZ injection. The renal cortical tissues were obtained and glomeruli were isolated. The protein expressions of JAK2, STAT3 and tyrosine phosphorylated STAT3 (p-STAT3) were assessed respectively by Western blot. Immunoprecipitation and Western blot analysis were used to determine tyrosine phosphorylated JAK2 (p-JAK2). JAK2 and STAT3 mRNA were assayed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Compared with the control group rats, the respective expression of JAK2, p-JAK2, STAT3, p-STAT3, JAK2 mRNA and STAT3 mRNA was significantly increased in the diabetic glomeruli without losartan treatment (all P<0.01). After treatment with losartan, the expression of p-JAK2 and p-STAT3 in the diabetic glomeruli was down-regulated (all P<0.05). However losartan had no effect on the expression of JAK2, STAT3, JAK2 mRNA and STAT3 mRNA in the diabetic glomeruli. CONCLUSION: JAK2 and STAT3 signal proteins may be involved in the kidney damage associated with diabetes. Regulation of phosphorylation of JAK2 and STAT3 may be responsible for the renal protective effects of losartan in diabetic rats.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2005

[Spectrum studies and application of the reaction system phenanthroline-EBT-H2O2].

A kinetic spectrophotometric method for the determination of trace phenanthroline was proposed. The method is based on the inhibition of phenanthroline to the discoloring reaction of EBT oxidized by hydrogen peroxide in the dilute acetic acid solution. At the same time, the kinetic parameters were studied in detail. Under optimum experimental conditions, the linear range is 0.003-0.08 mg x L(-1), and the detection limit is 4.0 microg x L(-1). The method is simple, rapid, and easy to operate. The method was applied to the determination of trace phenanthroline in water samples with satisfactory results.

Azo Compounds↗
PubMed2005

[Using protein chips to study mechanism underlying reversion of drug resistance in leukemia cells in tetrandrine alone or in combination with droloxifene].

The aim of this study was to investigate the mechanism to reverse the drug resistance of leukemia cells in tetrandrine (Tet) alone or in combination with droloxifen (Drol) by using protein chips and to lay the theoretical basis for the clinical applications. Three monoclonal antibodies against P-glycoprotein (P-gp), the multidrug resistance-associated protein (MRP1) and the breast cancer resistance protein (BCRP) were immobilized onto the agarose gel film-coated glass slides. Protein chips were prepared respectively from K562/A02 cells cultured for 12, 24 and 48 hours with Tet alone or in combination with Drol. The results showed that Tet alone or in combination with Drol could decrease only the expression of P-gp in a time-dependent manner, the effect for 48 hours as follows: Tet + Drol 82.620 +/- 3.227; Tet alone 86.440 +/- 2.906; Drol alone 87.230 +/- 2.049; control 93.670 +/- 2.748 (P < 0.05). However, down-regulation of P-gp by K562/A02 cells cultured with Tet alone or in combination with Drol began at 24 hours (Tet + Drol 85.270 +/- 3.095; control 93.670 +/- 2.748, P < 0.05). The results were coincident with that of FCM. It is concluded that Tet and Drol can downregulate the expression of P-gp in the time-dependent way. There is a significant difference between Tet alone and Tet combined with Drol at 24 hours (P < 0.05). The expression of MRP1 and BCRP are not closely correlated with the reversal mechanism of Tet and Drol, and which may be involved in the mechanism of this combination to reverse multidrug resistance in leukemia.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

[Detection of multidrug-resistance proteins with protein array chips].

OBJECTIVE: To evaluate the use of protein array chips in detection of multidrug-resistance proteins. METHODS: Human erythroleukemic cell line K562 and its doxorubicin-resistant counterpart K562/A02 were used in the study. Monoclonal antibodies against P-glycoprotein (P-gP), multidrug resistance-associated protein (MRP1) and breast cancer resistance protein (BCRP) were immobilized onto agarose film-coated glass. The antibody-cell binding was assessed by capturing K562 and K562/A02 cells. The protein array was observed under a microscope and the image was captured with a CCD camera. The expression levels of the three proteins were also measured by flow cytometry (FCM). RESULTS: The expression of P-gP and BCRP in K562 was very low. However, MRP1 expression was high. P-gP and MRP1 were highly expressed in K562/A02, while the expression of BCRP was low. FCM results showed that the expression rate of P-gP, MRP1 and BCRP in K562 cells was 5.98% +/- 2.19%, 95.80% +/- 3.98%, 1.03% +/- 0.45%, respectively, while that in K562/A02 cells was 92.67% +/- 1.80%, 97.18% +/- 1.02%, 3.98% +/- 0.37%, respectively. The results of protein array method are consistent with those of FCM (P > 0.05). CONCLUSION: It is feasible to develop a new protein array technique and to provide a novel method for multi-drug resistant cell detection, with a high throughput, high specificity, simple procedure and low cost.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

[Spectroscopic studies of interaction of brilliant cresyl blue and DNA].

The interaction of dye brilliant cresyl blue (BCB), which features a phenoxonium group, with hydroxypropyl-beta-cyclodextrinl and DNA in aqueous solution was studied by spectroscopic methods. The experimental results indicate that BCB can be included into the hydrophobic cavity of HP-beta-CD to form an inclusion, a complex with a stability constant of 1.98 x 10(3) L x mol(-1). At low DNA concentrations, BCB can be bound to DNA to form a 1:1 association complex with the binding constant of 4.3 x 10(4) mol x L(-1), and the major binding model of BCB to DNA is "electrostatic binding". However, the major binding model changes to "intercalative binding" at high DNA concentrations. In addition, the interactions of BCB-(HP-beta-CD) inclusion complex and DNA have been investigated. The results suggest that BCB displayed a high affinity for DNA and the inclusion complex decomposed when it was bound to DNA.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed2004

Cutting edge: TLR4 activation mediates liver ischemia/reperfusion inflammatory response via IFN regulatory factor 3-dependent MyD88-independent pathway.

The triggering molecular mechanism of ischemia-reperfusion injury (IRI), which in clinical settings results in excessive and detrimental inflammatory responses, remains unclear. This study analyzes the role of the TLR system in an established murine model of liver warm ischemia followed by reperfusion. By contrasting in parallel TLR knockout mice with their wild-type counterparts, we found that TLR4, but not TLR2, was specifically required in initiating the IRI cascade, as manifested by liver function (serum alanine aminotransferase levels), pathology, and local induction of proinflammatory cytokines/chemokines (TNF-alpha, IL-6, IFN-inducible protein 10). We then investigated the downstream signaling pathway of TLR4 activation. Our results show that IFN regulatory factor 3, but not MyD88, mediated IRI-induced TLR4 activation leading to liver inflammation and hepatocellular damage. This study documents the selective usage of TLR in a clinically relevant noninfectious disease model, and identifies a triggering molecular mechanism in the pathophysiology of liver IRI.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Direct fluorimetric determination of ascorbic acid by the supramolecular system of AA with beta-cyclodextrin derivative.

We established a simple and selective fluorimetric method for the determination of ascorbic acid (AA) with the novel mono-[6-N(4-carboxy-phenyl)]-beta-cyclodextrin (ACD). The method is based on the fluorescence intensity of ACD decreases as the ACD-AA supramolecular complexes form. The fluorescence intensity is measured at excitation and emission wavelengths of 270 and 352 nm, respectively. Under optimum condition, a linear relationship is obtained between the fluorescence intensity and the concentration of AA in the range of 0.05-8.0 microgml(-1). The detection limit is 0.012 microgml(-1). The method has been applied to the direct analysis of AA in real samples with satisfactory results.

Absorption↗