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Biomedical subjects

F Feng

Publications and source records attributed to F Feng.

At least 19 recordsLinked to original sources
PubMed2006

The complete mitochondrial genome sequence and characterization of single-nucleotide polymorphisms in the control region of the Asian seabass (Lates calcarifer).

We determined the complete mtDNA nucleotide sequence of Lates calcarifer using the shotgun sequencing method. The mitochondrial DNA (mtDNA) was 16,535 base pairs (bp) in length, and contained 13 protein coding genes, 22 transfer RNAs, 2 ribosomal RNAs, and one major noncoding control region (CR). The CR was unusually short at only 768 bp. A striking feature of the mitochondrial genome was the high G+C content (46.1%), which is among the highest in fish. The gene order was identical to that of a typical vertebrate. Phylogenetic analyses using concatenated amino acid sequences of 12 protein-coding genes of 30 fish species representing 14 suborders clearly showed Lates calcarifer was located in the cluster of fish species from the order Perciformes, supporting the traditional systematic classification. We characterized single-nucleotide polymorphisms (SNPs) in the CR by sequencing the complete CR of 25 individuals obtained from Australia and Singapore. A total of 68 SNPs were detected. Eighteen SNPs were fixed with alternative nucleotides in Australian and Singapore seabass, and these SNPs could be used for differentiating fish from the two countries.

Animals↗
PubMed2006

Characterization of two parvalbumin genes and their association with growth traits in Asian seabass (Lates calcarifer).

Parvalbumins are extremely abundant in fish muscle and play an important role in muscle relaxation. In this study, two parvalbumin genes (PVALB1 and PVALB2) were cloned from Asian seabass (Lates calcarifer). The cDNAs for PVALB1 and PVALB2 were 840 and 667 bp respectively. Both genes consisted of five exons and four introns, encoded 109 amino acids, and were of beta lineage. Using real-time polymerase chain reaction, expression of PVALB1 was detected in all 10 tissues tested, with expression in brain, kidney, muscle and small intestine being 15- to 322-fold higher than in the other tissues. Expression of PVALB2 was detected only in muscle, brain and intestine, and was up to 10-fold lower than PVALB1 expression. A (CT)(17) microsatellite in the 3'-untranslated region of PVALB1 and three single nucleotide polymorphisms (SNPs) in the third intron of PVALB2 were identified. The microsatellite in PVALB1 was significantly associated with body weight and body length at 90 days post-hatch (P < 0.01), whereas the SNPs in PVALVB2 were not associated with these traits.

3' Untranslated Regions↗
PubMed2006

Isolation, characterization, and linkage analyses of 74 novel microsatellites in Barramundi (Lates calcarifer).

Barramundi (Lates calcarifer) is an important marine food fish species in Southeast Asia and Australia. Seventy-four novel microsatellites were isolated from a genomic DNA library enriched for CA repeats and were characterized in 24 unrelated individuals. Among the 74 microsatellites, 71 were polymorphic, with an average allele number of 7.0 +/- 3.6/locus. The average expected heterozygosity of these polymorphic markers was 0.66. Sixty-three of the 71 polymorphic microsatellites conformed to Hardy-Weinberg equilibrium. Linkage analyses were conducted in a reference family, leading to the assignment of 34 novel microsatellites and 16 published markers in 16 linkage groups. The novel microsatellites developed in this study will contribute significantly to the construction of a first-generation linkage map for mapping of quantitative trait loci in Barramundi, and supply a large choice of markers for studies on population genetics, stock management, and pedigree reconstruction.

Animals↗
PubMed2006

Cellular interactions of virion infectivity factor (Vif) as potential therapeutic targets: APOBEC3G and more?

Vif is an HIV accessory protein whose primary function is to negate the action of APOBEC3G, a naturally occurring cellular inhibitor of HIV replication. Vif acts by binding to APOBEC3G, inducing its protein degradation within infected cells and reducing its levels in progeny virions. Interventions that interfere with the Vif-APOBEC3G interaction, raise intracellular or virion associated levels of APOBEC3G, or reduce intracellular levels of Vif, all could hold promise as potential therapeutic approaches aimed at enhancing the cells innate antiviral activity. Levels of APOBEC3G might be increased or Vif levels decreased, by strategies targeting protein synthesis, protein degradation or cellular localisation and function, and properties of APOBEC3G and Vif relevant to these strategies are discussed. Recent data have suggested that Vif may have other mechanisms of action apart from the above activities against APOBEC3G, including effects against other anti-viral mechanisms independent of APOBEC3G cytidine deaminase activity. In addition to interaction with APOBEC3G, Vif may have other accessory functions, which are discussed in relation to potential therapies that may affect multiple stages of the HIV life cycle. Future development of strategies that combine enhancement of APBOEC3G functional with inhibition of multiple Vif functions may become useful tools for HIV therapy.

APOBEC-3G Deaminase↗
PubMed2005

Near-infrared laser illumination transforms the fluorescence absorbing X-Gal reaction product BCI into a transparent, yet brightly fluorescent substance.

The beta-galactosidase protein generated by the bacterial LacZ gene is widely used to map gene expression patterns. The ease of its use is only rivaled by green fluorescent protein, which can be used in combination with various other procedures such as immunocytochemistry, flow cytometry, or tract tracing. The beta-galactosidase enzymatic reaction potentially provides a more sensitive assay of gene expression than green fluorescent protein. However, the virtual impermeability and tendency to absorb light over a wide range limit the use of the most frequently used beta-galactosidase substrate, X-Gal, in combination with other fluorescent labeling procedures. Here, we provide details on a simple photoactivation procedure that transforms the light-absorbing X-Gal product, 5-bromo-4-chloro-3-indolyl (BCI) precipitate, into an intensely fluorescent product excited by 488 and 633 nm light. Photoactivation is achieved through exposure to 730 nm near-infrared light emitted from a femtosecond titanium-doped Sapphire laser. Photoactivation of BCI occurs in tissue sections suspended in buffered saline, glycerol, or even embedded in epoxy resin. A protocol for the use of BCI photoactivation is here provided. Importantly, the BCI photoactivated product is photoswitchable, displaying bistable photochromism. This permits the use of the fluorescent product in a variety of co-localization studies in conjunction with other imaging modalities. As with other bistable and photoswitchable products, the BCI reaction product shows concentration quenching at high density and can be degraded by continuous exposure to intense 730 nm illumination. Therefore, care must be taken in developing imaging strategies. Our findings have implications for the use of X-Gal in gene and protein detection and provide a novel substrate for high density digital information storage.

Animals↗
PubMed2005

Smaller inner ear sensory epithelia in Neurog 1 null mice are related to earlier hair cell cycle exit.

We investigated whether co-expression of Neurog 1 and Atoh 1 in common neurosensory precursors could explain the loss of hair cells in Neurog 1 null mice. Analysis of terminal mitosis, using BrdU, supports previous findings regarding timing of exit from cell cycle. Specifically, we show that cell cycle exit occurs in spiral sensory neurons in a base-to-apex progression followed by cell cycle exit of hair cells in the organ of Corti in an apex-to-base progression, with some overlap of cell cycle exit in the apex for both hair cells and spiral sensory neurons. Hair cells in Neurog 1 null mice show cell cycle exit in an apex-to-base progression about 1-2 days earlier. Atoh 1 is expressed in an apex-to-base progression rather then a base-to-apex progression as in wildtype littermates. We tested the possible expression of Atoh1 in neurosensory precursors using two Atoh 1-Cre lines. We show Atoh 1-Cre mediated beta-galactosidase expression in delaminating sensory neuron precursors as well as undifferentiated epithelial cells at E11 and E12.5. PCR analysis shows expression of Atoh 1 in the otocyst as early as E10.5, prior to any histology-based detection techniques. Combined, these data suggest that low levels of Atoh 1 exist much earlier in precursors of hair cells and sensory neurons, possibly including neurosensory precursors. Analysis of Atoh 1-Cre expression in E18.5 embryos and P31 mice reveal beta-galactosidase stain in all hair cells but also in vestibular and cochlear sensory neurons and some supporting cells. A similar expression of Atoh 1-LacZ exists in postnatal and adult vestibular and cochlear sensory neurons, and Atoh 1 expression in vestibular sensory neurons is confirmed with RT-PCR. We propose that the absence of NEUROG 1 protein leads to loss of sensory neuron formation through a phenotypic switch of cycling neurosensory precursors from sensory neuron to hair cell fate. Neurog 1 null mice show a truncation of clonal expansion of hair cell precursors through temporally altered terminal mitosis, thereby resulting in smaller sensory epithelia.

Animals↗
PubMed2004

Chemosensitization of breast carcinoma cells with the use of bcl-2 antisense oligodeoxynucleotide.

This study was designed to observe whether the rates of apoptosis induced in the breast cancer cell line MCF-7 by 5-fluorouracil (5-FU) could be enhanced by transfecting bcl-2 antisense oligonucleotide (ASODN). In our experiment, bcl-2 ASODNs and control ODNs including untreated control, sense ODN and scrambled ODN, were transfected into MCF-7 cells. Changes in expression of the bcl-2 gene were examined by Western blot; cell growths were detected by MTT assay, and apoptosis rates were detected by flow cytometry (FCM). Expression of bcl-2 protein after transfection of bcl-2 ASODN was significantly lower than control ODNs. Moreover, incubation of MCF-7 with bcl-2 ASODN prior to 5-FU treatment caused remarkable loss of viable cells compared with all other control ODNs (P < 0.01). FCM showed the apoptosis rates for ASODN, untreated control, sense ODN and scrambled ODN (29.8 +/- 7.4)%, (8.0 +/- 2.3)%, (15.0 +/- 5.1)% and (16.5 +/- 7.1)%, respectively. Compared with control ODNs, ASODN achieved the strongest effect in terms of enhancing apoptosis (P < 0.01). These results suggest that combining bcl-2 ASODN with 5-FU led to synergistic cytotoxicity.

Antimetabolites, Antineoplastic↗
PubMed2004

Refinement in quantitative convergent beam electron diffraction (QCBED).

Quantitative convergent beam electronic diffraction (QCBED) method is a powerful tool for the investigation of the atomic and electronic structure of crystals. In this work, a global optimization algorithm has been adopted and a new fitting manner has been suggested in our recently developed QCBED program. A study of the charge density distribution in intermetallics is demonstrated as an example. Using the QCBED method, an investigation of lattice distortion in oxides is attempted.

Journal Article↗
PubMed2003

Autologous transplantation of gingival fibroblast-like cells and a hydroxylapatite complex graft in the treatment of periodontal osseous defects: cell cultivation and long-term report of cases.

Autogenous cell transplantation via hydroxylapatite (HA) vehicle has been reported to have beneficial effects on the treatment of human periodontal osseous defects. The aim of this study was to explore the possibility of using gingival fibroblast-like cells in the therapy of osseous defects caused by inflammatory periodontitis by reporting long-term results of gingival fibroblast-coated hydroxylapatite (GF-HA) grafting for healing these defects. Gingival fibroblasts were cultured from healthy gingivae of treated subjects. Growth of cells on HA particles was established in vitro, and then the GF-HA complex was transplanted into the periodontal osseous defects. Clinical parameters of gingival and plaque indices, probing depth, and periapical x-ray were monitored at baseline and at various periods from 50 months to 6 years after surgery. Grafting with only HA in the osseous defects of the same patient was used for comparison. The present study shows that GF-HA-treated sites could achieve marked pocket reduction and probing attachment gain at reentry and later recalls. Good clinical bone filling of osseous defects in GF-HA-treated sites was also demonstrated in periapical radiographs (increased bone height and reappearance of the crestal cortex) and in some reentry sites. One HA-treated site was filled with connective tissue only, and the absence of new bone formation was noted during a reentry operation. Another HA-treated site exhibited a comparable increase in radiographic density, while part of HA particles were gradually lost in longer recalls. These limited observations conclude that GF-HA grafting may provide a treatment modality leading to regeneration of periodontal tissues in periodontitis-affected osseous defects. Further studies including more cases and demonstration of the deposition of differentiated periodontal tissues are necessary before further application of this therapy.

Adult↗
PubMed2001

Akt1/PKBalpha is required for normal growth but dispensable for maintenance of glucose homeostasis in mice.

The serine-threonine kinase Akt, also known as protein kinase B (PKB), is an important effector for phosphatidylinositol 3-kinase signaling initiated by numerous growth factors and hormones. Akt2/PKBbeta, one of three known mammalian isoforms of Akt/PKB, has been demonstrated recently to be required for at least some of the metabolic actions of insulin (Cho, H., Mu, J., Kim, J. K., Thorvaldsen, J. L., Chu, Q., Crenshaw, E. B., Kaestner, K. H., Bartolomei, M. S., Shulman, G. I., and Birnbaum, M. J. (2001) Science 292, 1728-1731). Here we show that mice deficient in another closely related isoform of the kinase, Akt1/PKBalpha, display a conspicuous impairment in organismal growth. Akt1(-/-) mice demonstrated defects in both fetal and postnatal growth, and these persisted into adulthood. However, in striking contrast to Akt2/PKBbeta null mice, Akt1/PKBalpha-deficient mice are normal with regard to glucose tolerance and insulin-stimulated disposal of blood glucose. Thus, the characterization of the Akt1 knockout mice and its comparison to the previously reported Akt2 deficiency phenotype reveals the non-redundant functions of Akt1 and Akt2 genes with respect to organismal growth and insulin-regulated glucose metabolism.

Alleles↗
PubMed2001

[Diagnosis and treatment of pulmonary embolism during pregnancy].

OBJECTIVE: To study high risk factors, clinical presentation, diagnosis and treatment of pulmonary embolism (PE) during pregnancy and postpartum. METHODS: Two patients with pulmonary embolism were reported retrospectively. RESULTS: The 1st case was a pregnant woman with congenital heart disease at 39 weeks gestation, who underwent uneventful cesarean section (CS) because of heart disease, but she had tachycardia, tachypnea, cyanosis, dyspnea suddenly on the 10 days after CS and died immediately after the onset of above symptoms, the diagnosis of PE was highly suspected clinically. The 2nd case was a pregnant women with twin gestation, at 35 weeks, because of severe prenatal myocardiopathy, cesarean section was performed, Maternal death occurred suddenly during the surgery. The diagnosis of PE was confirmed by autopsy. CONCLUSIONS: The maternal mortality of PE during pregnancy and postpartum is very high, whenever there is any suspects, the objective examination for PE should be started early in order to get the chance to give anticoagulant therapy.

Adult↗
PubMed2001

[Clinical study of topotecan in the treatment of small cell lung cancer and recurrent ovarian cancer].

OBJECTIVE: To evaluate the effect and adverse reaction of China made topotecan in the treatment of small-cell lung cancer (ACLC) and recurrent ovarian cancer (OV). METHODS: From January to July, 2000, topotecan was used to treat 141 patients at a dose of 1.2 mg/m2, given daily as 30-min i.v. infusion for 5 days. Treatment was repeated once every 3 weeks. Of the 141 patients, 118 were evaluable for therapeutic efficacy. All the patients received a total of 286 cycles of treatment were assessable for analysis of adverse reactions. RESULTS: Among the evaluable patients, there were 5 CR, 35 PR, with an overall response rate (RR) of 33.8%. There were 3 CR and 26 PR in 89 patients with SCLC (RR 32.5%). The response rate of patients with or without prior chemotherapy was 15.6% and 50%, respectively. In 29 patients with recurrent OV, there were 2 CR and 9 PR (RR 37.9%). The major toxic effect was myelosuppression. Non-hematopoietic toxicities were mild and tolerable. CONCLUSION: Topotecan is an effective drug for the treatment of SCLC and recurrent OV. It is still efficacious in some patients who previously received standard chemotherapy. The major dose-limiting toxicity is myelosuppression. The response rate and toxicity of the domestically made topotecan are comparable with those of the imported one.

Adolescent↗
PubMed2001

[Modulation of human small cell lung cancer cell line GLC4/ADR multidrug resistance in the inhibition of multidrug resistance-associated protein and its antisense].

OBJECTIVE: To study the effect of antisense multidrug resistance-associated protein (MRP) RNA on multidrug resistance (MDR) in the human small cell lung cancer (SCLC) cell line GLC4/ADR, in which the overexpression of MRP gene is discovered. METHODS: In using the plasmid pRC/RSV-MRP1 containing complete ORF of MRP as a template, two antisense recombinants targeting at the 5' and 3' regions were constructed with the application of the polymerase chain reaction (PCR) technique. Lipofectamine was conducted to transduce these antisense MRPs into the GLC4/ADR cells. Three clones (the GLC4/ADR-pcDNA3, MO; GLC4/ADR-MRP-5' region, Ma; GLC4/ADR-MRP-3' region, Mb) of transfectants after the selection of G418 were obtained. The expression of MRP protein was detected by the use of the Western blot and the MTT method for determination of chemosensitivity to ADR was used. RESULTS: The antisense MRPs was found to be effectively expressed in the clones, being transfected with two different antisense MRPs. The MRP expression in these transfectants were inhibited at the rates of 14.0% (GLC4/ADR Ma) and 83.0% (GLC4/ADR Mb), respectively. Moreover, decrease in the ADR resistance was observed in the Ma and Mb at the rates of 9.5% and 28.4%. Although the intracellular ADR concentration was increased in these transfectants, the proliferation and cell cycle and their early apoptosis induced by the ADR, indicated no difference between the transfectants and parental cells. CONCLUSION: It is possible to obtain the effective expression of the MRP antisense structures for the blocking of the mRNA translation in GLC4/ADR cell line and the fragment complementary to the 3'-region of MRP is more effective for the inhibition of the MRP than that related to the 5'-region of MRP. The antisense RNA may be a useful treatment in combination with the conventional chemotherapy for SCLC, in which the MRP overexpression usually occurs.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2001

[The relationship between cadmium-induced inhibition of splenic lymphocyte function and cell apoptosis].

OBJECTIVE: To explore the relationship between cadmium-induced inhibition of splenic lymphocyte function and cell apoptosis in vitro. METHODS: The splenic lymphocytes of mice were exposed to 3.10, 6.25, 12.50, 25.00, 50.00 micromol/L of cadmiun chloride (CdCl(2)) for various time period, to measure the lymphocyte transformation by MTT colorimetric assay and to detect the apoptosis in splenocytes by DNA agarose electrophoresis and flow cytometry (FACS). RESULTS: CdCl(2) could significantly inhibit the function of lymphocyte transformation in a dose-response pattern at concentrations of 25.00 and 50.00 micromol/L, with inhibition rates of 50% and 78% in ConA-stimulating group and 39% and 55% in LPS-stimulating group, respectively. CdCl(2) could also induce apoptosis of splenic cells at concentrations of 12.50 to 50.00 micromol/L. RESULTS: of FACS analysis showed 30% - 60% of cell apoptosis. Higher concentration of CdCl(2) could also cause reduction of cell survival. Effect of Cd-induced apoptosis was earlier and at a lower concentration of CdCl(2) than that of Cd-induced inhibition of lymphocyte transformation. CONCLUSION: CdCl(2) could induce cell apoptosis in vitro, which was one of the mechanisms of its suppression of lymphocyte function.

Animals↗
PubMed2001

[Safety and immunogenicity of a new inactivated hepatitis A vaccine].

BACKGROUND: To evaluate the safety and immunogenicity of a new inactivated hepatitis A virus (HAV) vaccine. METHODS: In a randomized controlled trail thirty-one HAV-seronegative adults were enrolled and randomly assigned to either study group or control group. Subjects in the study group were given 1000 units of the new inactivated HAV vaccine, with a booster at 3 months. Subjects in the control group were given 720 ELISA units Havrix, produced by SmithKline Beecham Biologicals, with a subsequent dose at 3 months. Local and systematic reactions and serum response to the vaccines were compared between the two groups. RESULTS: Mild local reactions were noted in one subject from the study group and two from the control group after primary vaccination. Mild systematic reactions were reported in two subjects from each group after primary vaccination and in one subject from the study group after booster vaccination. Seroconversion rates were 94%, 100%, and 100% in the study group at 1, 3, and 4 (1 month after booster) month, respectively. The corresponding figures were 73%, 80% and 100% in the control group. Geometric mean antibody titers were 139.2 mIU/ml, 137.7 mIU/ml, and 1 066.7 mIU/ml at 1, 3, and 4 months,respectively, in the study group,and 104.3 mIU/ml, 111.3 mIU/ml, and 760.7 mIU/ml in the control group. CONCLUSIONS: The new inactivated hepatitis A vaccine was safe and highly immunogenic.

Adolescent↗
PubMed2000

Mammary tumor development in MMTV-c-myc/MMTV-v-Ha-ras transgenic mice is unaffected by osteopontin deficiency.

Transgenic mice expressing c-myc and v-Ha-ras specifically in the mammary gland under the control of the mammary specific promoter MMTV develop unifocal mammary tumors with a half time of about 46 days, and these tumors express high levels of osteopontin mRNA and protein. In order to evaluate the requirement for osteopontin expression by these tumors, we have crossed transgenic mice expressing these two oncogenes with mice with a targeted disruption of the osteopontin gene. Littermates expressing both myc and ras, and with either wild-type or disrupted OPN alleles were evaluated for tumor incidence and growth rate. Both of these parameters were found to be unaffected by a lack of osteopontin in the whole animal. Ras and myc expression level, measured at the level of mRNA, was not different in tumors of the two genotypes. Macrophage accumulation, while extremely variable among different tumors, did not correlate with the OPN status of the animals. Expression of the related gene BSP was not detected in any of the tumors, and was similar in bones of wildtype and OPN -/- mice. Similarly, the vitronectin gene was expressed at very low levels in tumors of either genotype. These results indicate that despite its high level of expression, OPN is either not required for mammary primary tumor formation and growth in this system, or can be replaced by molecules other than BSP and vitronectin in mice that totally lack osteopontin.

Animals↗
PubMed2000

[Clinical analysis of 10 cases of true histiocytic lymphoma].

OBJECTIVE: To explore the clinical and pathological characteristics of true histiocytic lymphoma. METHODS: The clinical and pathological data of 10 true histiocytic lymphoma patients admitted between 1986 and 1996 to our hospital was retrospectively reviewed. RESULTS: True histiocytic lymphoma accounted for 0.6% of non-Hodgkin's lymphoma(NHL) admitted in this period to our hospital. Enzymes associated with true histiocytic lymphoma were detected in all the 10 cases. The tumor cells were excluded from T/B lymphoid origin in 6 cases by immunohistochemistry. Eight cases received chemotherapy + irradiation +/- excision of primary lesion, 1 simply received irradiation and 1 received bone marrow transplantation. The response rate was 100%, with a 1, 3 and 5 year survival rate of 100%, 90% and 70%, respectively. The expected 10 year disease free survival rate is 40%. CONCLUSION: True histiocytic lymphoma is a rare subset of NHL. Those originated from lymph node are sensitive to chemotherapy and irradiation with a favorable prognosis.

Adolescent↗