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Biomedical subjects

Feng Li

Publications and source records attributed to Feng Li.

At least 181 records · Page 10Linked to original sources
PubMed2004

Downregulation of ATP synthase subunit-6, cytochrome c oxidase-III, and NADH dehydrogenase-3 by bright cyclic light in the rat retina.

PURPOSE: Retinas of albino rats born and raised in bright cyclic light (300-800 lux) are less susceptible to light-induced apoptosis than retinas of animals born and raised in dim cyclic light (5 lux). In this study, the objective was to study the mechanisms of neuroprotection in the bright cyclic light-reared retina by identification of differentially expressed genes with differential display (DD)-PCR. METHODS: Albino rats were born and raised in 5- or 400-lux cyclic light (12 hours on/off). At 6 to 8 weeks of age, animals were either killed to harvest retinas or exposed to 1700 lux illumination for 12 or 24 hours. The neuroprotection of 400-lux cyclic light rearing was evaluated by DNA fragmentation and quantitative histology. The differentially expressed candidate genes were identified by DD-PCR. Northern blot analysis was used to quantitate differential expression of selected genes. Differential expression of protein was determined by Western blot and enzyme activity analysis. Cellular localization of transcripts was determined by in situ hybridization. RESULTS: DNA fragmentation and quantitative histology results indicated that 400-lux cyclic light rearing protected the retina from light-induced apoptosis compared with 5-lux cyclic light rearing. DD-PCR analysis showed that a 283-bp expressed sequence tag (EST) was downregulated in retinas of rats raised from birth in 400-lux cyclic light. A BLAST search identified the EST as the 3'-terminal sequence of mitochondria-encoded NADH dehydrogenase subunit 3 (ND-3). Northern blot analysis showed that the EST hybridized to two mRNA transcripts, the larger of which was confirmed to encompass the adenosine triphosphate (ATP) synthase subunit 6 (ATPase-6), cytochrome c oxidase subunit III (CO-III), ND-3, and tRNA-Gly. Northern blot analysis demonstrated that CO-III and ATPase-6 were downregulated 1.8- and 2.3-fold by 400-lux cyclic light compared with 5-lux cyclic light, respectively; however, there was no change in cytochrome c oxidase subunit I and II (CO-I and -II) or in 12S ribosomal RNA (12S rRNA), a mitochondrial housekeeping gene. Western blot analysis using anti-CO-III antibody showed more CO-III protein in retinal mitochondria from dim-light-raised rats. The enzyme activity of CO was two times higher in retinal homogenates from dim-light-raised rats than those from bright-light-raised rats. In situ hybridization using a (35)S-labeled CO-III probe showed that the CO-III transcript was present and downregulated in most of the retinal layers of bright-light-reared animals. CONCLUSIONS: Rearing in cyclic light at 400-lux downregulates the expression of ATPase-6, CO-III, and ND-3 compared with rearing in 5-lux cyclic light. The authors hypothesize that these changes are adaptive responses to light stress that provide neuroprotection to retinal cells by elevating the level of stress-related factors and reducing the level of oxidized cytochrome c, the form that activates the apoptotic cascade of cell death.

Adaptation, Ocular↗
PubMed2004

Radiologists' performance for differentiating benign from malignant lung nodules on high-resolution CT using computer-estimated likelihood of malignancy.

OBJECTIVE: The purpose of our study was to evaluate whether a computer-aided diagnosis (CAD) scheme can assist radiologists in distinguishing small benign from malignant lung nodules on high-resolution CT (HRCT). MATERIALS AND METHODS: We developed an automated computerized scheme for determining the likelihood of malignancy of lung nodules on multiple HRCT slices; the likelihood estimate was obtained from various objective features of the nodules using linear discriminant analysis. The data set used in this observer study consisted of 28 primary lung cancers (6-20 mm) and 28 benign nodules. Cancer cases included nodules with pure ground-glass opacity, mixed ground-glass opacity, and solid opacity. Benign nodules were selected by matching their size and pattern to the malignant nodules. Consecutive region-of-interest images for each nodule on HRCT were displayed for interpretation in stacked mode on a cathode ray tube monitor. The images were presented to 16 radiologists-first without and then with the computer output-who were asked to indicate their confidence level regarding the malignancy of a nodule. Performance was evaluated by receiver operating characteristic (ROC) analysis. RESULTS: The area under the ROC curve (Az value) of the CAD scheme alone was 0.831 for distinguishing benign from malignant nodules. The average Az value for radiologists was improved with the aid of the CAD scheme from 0.785 to 0.853 by a statistically significant level (p = 0.016). The radiologists' diagnostic performance with the CAD scheme was more accurate than that of the CAD scheme alone (p < 0.05) and also that of radiologists alone. CONCLUSION: CAD has the potential to improve radiologists' diagnostic accuracy in distinguishing small benign nodules from malignant ones on HRCT.

Diagnosis, Differential↗
PubMed2004

Efficient delivery of human clotting factor IX after injection of lentiviral vectors in utero.

AIM: To explore gene transfer feasibility for human clotting factor IX (hFIX) mediated by recombinant lentivirus in utero. METHODS: ICR mice fetus at 17-19 d gestation were received lentiviral vectors carrying hFIX cDNA under the control of liver specific promoter by intrahepatic injection. The expression and distribution of hFIX cDNA and possible immune responses against the hFIX were assessed by ELISA, PCR, RT-PCR, and immunohistochemistry, respectively. RESULTS: The serum hFIX protein were detected at different time points in all newborn mice, the highest level of hFIX was 50 microg/L and lasted for more than 30 d. Anti-hFIX antibody was not detected. hFIX cDNA was detected in liver, spleen, and heart. The expression of hFIX cDNA was only detected in liver. Besides, no germ line transmission was found at DNA and RNA levels, and no side effect associated with gene transfer was detected. CONCLUSION: The efficient delivery of hFIX can be achieved by prenatal gene transfer. It thus shows the feasibility of gene therapy for hemophilia in utero.

Animals↗
PubMed2004

[Research advance in ecosystem service of urban green space].

In this paper, the concept and connotation of urban green space and ecosystem service were expatiated, and the research advance in ecosystem service of urban green space was reviewed. The studies of ecosystem service of urban green space in overseas were focused on improving the quality of urban environment, maintaining biodiversity, providing amenity values, and ecosystem management; while in China, they were focused on the structure and function of urban green space, green quantity and quality, green equivalent, indicator system evaluation, value assessment, and application of CITYgreen model. The shortages and prospects of the researches on ecosystem service of urban green space were put forward.

Biodiversity↗
PubMed2004

Effect of ketamine on NF-kappa B activity and TNF-alpha production in endotoxin-treated rats.

The effects of ketamine on endotoxin-induced NF-kappaB activation and TNF-alpha expression were studied in vivo. A sepsis model was created by bolus injection of endotoxin (5 mg/kg) into the tail vein of adult Wistar rats. The rats were immediately treated with various doses of ketamine (0.5, 5, or 50 mg/kg) or 0.9% NaCl (10 ml/kg) i.p. At 1, 4, or 6 hr post-treatment, NF-kappaB and TNF-alpha were assayed in the intestine, liver, and lung by electrophoretic mobility shift assay (EMSA) and reverse-transcription polymerase chain reaction (RT-PCR), respectively. Serum TNF-alpha was analyzed by ELISA. Endotoxin enhanced NF-kappaB activity and TNF-alpha expression in the intestine, liver, and lung and it increased TNF-alpha concentration in serum. Ketamine dosages 0.5 mg/kg suppressed the endotoxin-induced NF-kappaB activation and TNF-alpha expression in the intestine. The lowest dose to inhibit NF-kappaB activity and TNF-alpha expression in the lung was 5 mg/kg. Ketamine did not inhibit endotoxin-induced NF-kappaB activity or TNF-alpha expression in the liver; ketamine itself at a dose of 50 mg/kg enhanced NF-kappaB activity and TNF-alpha expression in the liver. Ketamine dosage 0.5 mg/kg inhibited endotoxin-induced TNF-alpha elevation in the serum. In conclusion, ketamine can suppress the induction of NF-kappaB and TNF-alpha by endotoxin in vivo. Subanesthetic dosages of ketamine have an anti-inflammatory effect, but large dosages may be harmful.

Animals↗
PubMed2004

[Effect of low intensity and very high frequency electromagnetic radiation on occupationally exposed personnel].

OBJECTIVE: To investigate the effect of low intensity and very high frequency (VHF) electromagnetic radiation (170 MHz) on nervous system function and serum enzymes and immune function in human subjects with occupational exposure to VHF. METHODS: To measure the intensity of VHF and other environmental factors on the spot, to hold the questionnaire about chief complaints, to examine the rheoencephalography and the neurobehavior function, to analyze ALT, AST, ALP and LDH, and IgA, IgM and IgG in experimental group and control group. RESULTS: The intensity of VHF (direction of antenna: 0 degrees, 10 m and 135 degrees, 20 m) was higher than that of national standard on-the-spot. The incidences of symptoms such as headache, insomnia and amnesia etc. was significantly higher in experimental group (P < 0.01). Rheoencephalography indicated that the raising time of both left [(0.155 3 +/- 0.057 9) s] and right [(0.154 1 +/- 0.059 2) s] in the experimental group after exposure were significantly longer than before exposure [(0.104 4 +/- 0.030 2) s, (0.103 2 +/- 0.030 4) s respectively] or in the control [(0.118 5 +/- 0.056 8) s, (0.117 7 +/- 0.057 5) s respectively, (P < 0.01)]. Neurobehavior function test showed that digital symbol, digital span and pursuit aiming test were decreased after exposure in the experimental group (P < 0.01). Serum enzyme analysis showed that AST, ALP and LDH were significantly increased after exposure in the experimental group (P < 0.01). No marked change was found in IgA level, while the levels of IgM and IgG after exposure in the experimental group especially the latter were significantly increased (P < 0.01). CONCLUSIONS: Low-intensity VHF radiation can decrease the nervous system function in occupationally exposed personnel and induce increase in some kinds of enzymes and immunoglobulins.

Adolescent↗
PubMed2004

Chemokine-like factor 1, a novel cytokine, contributes to airway damage, remodeling and pulmonary fibrosis.

BACKGROUND: Chemokine-like factor 1 (CKLF1) was recently identified as a novel cytokine. The full-length CKLF1 cDNA contains 530 bp encoding 99 amino acid residues with a CC motif similar to that of other CC family chemokines. Recombinant CKLF1 exhibits chemotactic activity on leucocytes and stimulates proliferation of murine skeletal muscle cells. We questioned whether CKLF1 could be involved in the pathogenesis of inflammation and proliferation in the lung. Therefore we used efficient in vivo gene delivery method to investigate the biological effect of CKLF1 in the murine lung. METHODS: CKLF1-expressing plasmid, pCDI-CKLF1, was constructed and injected into the skeletal muscles followed by electroporation. Lung tissues were obtained at the end of week 1, 2, 3 and 4 respectively after injection. The pathological changes in the lungs were observed by light microscope. RESULTS: A single intramuscular injection of CKLF1 plasmid DNA into BALB/c mice caused dramatic pathological changes in the lungs of treated mice. These changes included peribronchial leukocyte infiltration, epithelial shedding, collagen deposition, proliferation of bronchial smooth muscle cells and fibrosis of the lung. CONCLUSIONS: The sustained morphological abnormalities of the bronchial and bronchiolar wall, the acute pneumonitis and interstitial pulmonary fibrosis induced by CKLF1 were similar to phenomena observed in chronic persistent asthma, acute respiratory distress syndrome and severe acute respiratory syndrome. These data suggest that CKLF1 may play an important role in the pathogenesis of these important diseases and the study also implies that gene electro-transfer in vivo could serve as a valuable approach for evaluating the function of a novel gene in animals.

Animals↗
PubMed2004

[Detection of EWS-FLI1 fusion transcript in Ewing's sarcoma/peripheral primitive neuroectodermal tumors by one-step RT-PCR using paraffin-embedded tissues].

OBJECTIVE: To investigate the expression of EWS-FLI1/ERG fusion transcript resulting from t(11;12)(q24;12) in paraffin-embedded tissues and its diagnostic implication for Ewing's sarcoma/peripheral primitive neuroectodermal tumors (ES/pPNET). METHODS: One-step reverse transcriptase-polymerase chain reaction (RT-PCR) was employed to detect a characteristic EWS-FLI1/ERG fusion transcript in 25 cases of ES/pPNET and 15 cases of other small round cell tumors (including 8 cases of rhabdomyosarcoma, 4 cases of synovial sarcoma, 2 cases of neuroblastoma and 1 case of lymphoma) using formalin-fixed and paraffin-embedded tissues. RESULTS: EWS-FLI1/ERG fusion transcript was detected in 20 of the 25 ES/pPNET cases (80%). The 15 non-ES/pPNET control cases were negative for EWS-FLI1/ERG fusion transcript. CONCLUSIONS: Detection of EWS-FLI1/ERG fusion transcript is a reliable index for molecular diagnosis of ES/pPNET. One-step RT-PCR is a practical method for such analysis in routine paraffin-embedded tumor tissues.

Adolescent↗
PubMed2004

[Reconstruction and expression of green fluorescent protein and aquaporin 7 fusion recombinant vector].

OBJECTIVE: To study the membrane mobility of aquaporin 7 (AQP7) by cloning stably transfected CHO cells with expression of pEGFP-C1-AQP7, in which AQP7 cDNA was fused downstream and in frame to pEGFP-C1 gene. METHODS: The full sequence of AQP7 was amplified by RT-PCR and then recombined in the downstream of the green fluorescent protein gene in the pEGFP-C1 vector. The recombinant vector pEGFP-C1-AQP7 was stably transfected into CHO cells. With fluorescent microscopy, immunocytochemical stain and Western blot, pEGFP-C1-AQP7 showed a predominant intracellular vesicular localization. RESULTS: (1) The sequence of AQP7 cDNA of the Wistar rat was logged into the GenBank (access number: AY157737). (2) Identification demonstrated that pEGFP-C1-AQP7 fusion protein stably expressed in CHO cells. (3) With fluorescence microscopy, pEGFP-C1-AQP7 showed a predominant intracellular vesicular localization. CONCLUSION: The CHO cell line with stable pEGFP-C1-AQP7 expression was set up successfully for advanced research.

Animals↗
PubMed2004

[Detection of ASPL-TFE3 fusion gene by reverse transcriptase polymerase chain reaction in paraffin-embedded tumor tissues of alveolar soft part sarcoma].

OBJECTIVE: To investigate the significance of detecting chimeric mRNA resulting from t(X;17)(p11.2;q25) in paraffin-embedded tumor tissues of alveolar soft part sarcoma (ASPS). METHODS: Formalin-fixed, paraffin-embedded tumor tissues from 8 cases of alveolar soft part sarcoma and 15 cases of controls (including 6 alveolar rhabdomyosarcomas, 6 renal cell carcinomas, 2 paragangliomas and 1 granular cell myoblastoma) were retrieved from the archival materials. ASPL-TFE3 fusion transcripts were analyzed in all samples by reverse transcriptase-polymerase chain reaction (RT-PCR). The quality of the mRNA was assessed using the house-keeping gene beta-actin. RESULTS: ASPL-TFE3 fusion transcripts were detected in 6 of the 8 ASPS cases (4 being type 2 and 2 being type 1). The remaining 2 cases were negative for both beta-actin and ASPL-TFE3. No ASPL-TFE3 mRNA expression was detected in all the controls. PAX3/7-FKHR fusion transcripts were also detected in 4 of the 6 alveolar rhabdomyosarcoma samples. CONCLUSIONS: The expression of ASPL-TFE3 fusion transcripts in paraffin-embedded tumor tissues can serve as an useful molecular marker in the diagnosis of ASPS. It may also be helpful in elucidating the underlying pathogenesis of ASPS in subsequent retrospective studies.

Adolescent↗
PubMed2004

[Changes in uncoupling protein-2, 3 mRNA expression in the scalded rats after escharectomy at different post scalding stages].

OBJECTIVE: To investigate the expression of uncoupling protein (UCP)-2, 3 mRNA in skeletal muscle of the scalded rats after escharectomy at different post scalding stages. METHODS: One hundred and twenty Wistar rats were employed in the study, in which 8 served as normal control (C) and 112 were subjected to 30% TBSA 3rd degree scalding and then again, divided into 4 groups. The rats in A group were sacrificed on 8th, 24th, 96th, 120th and 168th post scalding hours (PSHs) without escharectomy. The rats in B group underwent escharectomy at 8 PSH, and those in C group underwent escharectomy at 24 PSH. All the rats in both groups were sacrificed on 96, 120 and 168 PSHs after escharectomy, Escharectomy was performed at 96 PSH in rats of D group, and they were sacrificed on 120 and 168 PSHs after escharectomy. The serum levels of leptin and TNFalpha, and the expression level of UCP2 mRNA were determined at all time points in all groups of rats. RESULTS: (1) The serum levels of leptin in A group were obviously lower than that in C group (P < 0.01) during 24 approximately 168 PSHs, while those in B, C and D groups were much higher than those in A group (P < 0.01) during 24 approximately 168 PSH. (2) The serum TNFalpha levels in A group at all time points were higher than that in control group, while that in B group at all time points were lower than that in A group (P < 0.05 or 0.01), and that in C group at 168 PSH was lower than that in A group (P < 0.05). (3) The UCP2 mRNA expression in skeletal muscle in A group was increased evidently since 8 PSH (P < 0.01), peaking at 24 PSH and lowering thereafter, while that in B and C groups at 168PSH was significantly lower than that in A group at the same time points (0.32 and 0.35 vs 0.71, P < 0.05). The trend of the change in UCP3 mRNA expression in skeletal muscle was similar to that of UCP2. CONCLUSION: The postburn up-regulation of UCP mRNA expression might play important roles in the increase of metabolic rate. Escharectomy during shock stage could lower down the expression of UCP2 and UCP3 mRNA expression, and it could be beneficial by lowering metabolic rate.

Animals↗
PubMed2004

[Establishment of 2-dE map of human low differentiation nasopharyngeal carcinoma cell line CNE-2 proteome].

OBJECTIVE: To establish a two-dimensional polyacrylamide gel electrophoresis (2-DE) map of human low differentiation nasopharyngeal carcinoma (NPC) cell line CNE-2 proteome. METHODS: Immobilized pH gradient 2-DE was applied to separate the total proteins of CNE-2 cells, matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) and database searching were used to indentify proteins. RESULTS: A good 2-DE pattern with high resolution and reproducibility was obtained. Seventy-eight protein spots were incised from sliver staining gel and digested in gel by trypisin. Of them 77 maps of peptide mass fingerprints (PMF) were obtained and 48 proteins were identified. CONCLUSION: A reference 2-DE map of CNE-2 proteome has been established and the data coupled with similar proteome analysis of other NPC cell lines will expand the human nasopharyngeal carcinoma proteome database.

Amino Acid Sequence↗
PubMed2003

Synthesis of porous wires from directed assemblies of nanospheres.

A method is reported for the fabrication of wires with extended pore structures. Nanospheres are initially infiltrated into the one-dimensional channels of alumina or polymer porous membranes. Metal is then electrochemically deposited within the channels. Removal of the membrane and nanospheres results in porous wires. The production of 1-mum diameter wires with 300- or 500-nm diameter pores and 300-nm diameter wires with 140-nm pores illustrates the utility of this approach. Contacts between the spheres and the channel wall result in openings on the surface of the wires, and contacts between the spheres themselves produce openings between adjacent pores. Some short-range ordering of the spheres within the channels, as reflected in the wire pore structure, is evident. Characterization of the porous wires by electron microscopy is presented, and the potential applications of materials is discussed.

Journal Article↗
PubMed2003

[Detection of PAX3/PAX7-FKHR fusion transcript in rhabdomyosarcoma by one-step RT-PCR].

OBJECTIVE: To detect the PAX3-FKHR and PAX7-FKHR fusion transcripts in formalin-fixed, paraffin-embedded rhabdomyosarcoma tissues by one-step RT-PCR and discuss its diagnostic potential. METHODS: One-step RT-PCR were used to detect the expression of the PAX3-FKHR and PAX7-FKHR fusion transcripts in 15 cases of rhabdomyosarcoma (6 cases of ARMS, 9 cases of ERMS and 1 case of PRMS) and 15 cases of non-rhabdomyosarcomous small round cell tumor. RESULTS: PAX3-FKHR and PAX7-FKHR fusion transcripts were positive in 3/6 and 1/6 of ARMS patients, respectively, and were all negative in ERMS, PRMS and Control tumors including 4 cases of synovial sarcoma,4 cases of Ewing's sarcoma,4 cases of lymphoma and 3 cases of neuroblastoma. CONCLUSION: Expression of PAX3-FKHR and PAX7-FKHR fusion transcripts detected by one-step RT-PCR is useful in diagnosis and classification of rhabdomyosarcoma.

DNA-Binding Proteins↗
PubMed2003

Microwave-assisted synthesis of diaryl ethers without catalyst.

[reaction: see text] Diaryl ethers have been prepared by direct coupling of phenols including those that bear a strong electron-attracting substituent to electron-deficient aryl halides through S(N)Ar-based addition reactions with assistance of microwave irradiation in high to excellent yields within 5-10 min. No catalysts were required under our conditions.

Hydrocarbons, Aromatic↗
PubMed2003

Spatial distribution and specification of mammalian replication origins during G1 phase.

We have examined the distribution of early replicating origins on stretched DNA fibers when nuclei from CHO cells synchronized at different times during G1 phase initiate DNA replication in Xenopus egg extracts. Origins were differentially labeled in vivo versus in vitro to allow a comparison of their relative positions and spacing. With nuclei isolated in the first hour of G1 phase, in vitro origins were distributed throughout a larger number of DNA fibers and did not coincide with in vivo origins. With nuclei isolated 1 h later, a similar total number of in vitro origins were clustered within a smaller number of DNA fibers but still did not coincide with in vivo origins. However, with nuclei isolated later in G1 phase, the positions of many in vitro origins coincided with in vivo origin sites without further change in origin number or density. These results highlight two distinct G1 steps that establish a spatial and temporal program for replication.

Animals↗
PubMed2003

MICoA, a novel metastasis-associated protein 1 (MTA1) interacting protein coactivator, regulates estrogen receptor-alpha transactivation functions.

The transcriptional activity of estrogen receptor-alpha (ER-alpha) is modified by coactivators, corepressors, and chromatin remodeling complexes. We have previously shown that the metastasis-associated protein-1 (MTA1), a component of histone deacetylase and nucleosome remodeling complexes, represses ER-driven transcription by recruiting histone deacetylases to the estrogen receptor element (ERE)-containing target gene chromatin in breast cancer cells. Using a yeast two-hybrid screening to clone MTA1-interacting proteins, we identified a previously uncharacterized molecule, which we named as MTA1-interacting coactivator (MICoA). Our findings suggest that estrogen signaling promotes nuclear translocation of MICoA and that MICoA interacts with MTA1 both in vitro and in vivo. MICoA binds to the C-terminal region of MTA1, whereas MTA1 binds to the N-terminal MICoA containing one nuclear receptor interaction LSRLL motif. We showed that MICoA is an ER coactivator, cooperates with other ER coactivators, stimulates ER-transactivation functions, and associates with the endogenous ER and its target gene promoter chromatin. MTA1 also repressed MICoA-mediated stimulation of ERE-mediated transcription in the presence of ER and ER variants with naturally occurring mutations, such as D351Y and K303R, and that it interfered with the association of MICoA with the ER-target gene chromatin. Because chromatin is a highly dynamic structure and because MTA1 and MICoA could be detected within the same complex, these findings suggest that MTA1 and MICoA might transmodulate functions of each other and any potential deregulation of MTA1 is likely to contribute to the functional inactivation of the ER pathway, presumably by derecruitment of MICoA from ER target promoter chromatin.

Amino Acid Sequence↗