Biomedical subjects

Feng Gao

Publications and source records attributed to Feng Gao.

At least 145 records · Page 8Linked to original sources

PubMed2005

Analysis of the therapeutic effect of sodium copper chlorophyllin tablet in treating 60 cases of leukopenia.

OBJECTIVE: To evaluate the efficacy and safety of sodium copper chlorophyllin (trademarked as "Yebaike Tablet which is abbreviated as YBK in treating leukopenia. METHODS: One hundred and five patients with leukopenia caused by various factors were randomized into 3 groups. The 60 patients in the YBK group took orally YBK Tablets at the dose of 40 mg, three times per day, the 30 patients in the leucogen group were treated with Leucogen Tablets at the dose of 20 mg, three times per day, and the 15 patients in the placebo group were administered with vitamin C tablets 100 mg, three times per day. All the subjects were treated for 1 month. The change of peripheral leucocytes count after treatment and adverse drug reaction that occurred in patients were studied. RESULTS: In the 60 patients treated with YBK, the treatment proved to be markedly effective in 34 cases, effective in 17 and ineffective in 9, the total effective rate being 85%, which was significantly higher than that in the placebo group (26.7%, P < 0.01) and similar to that in the leucogen group (83.3%, P > 0.05). No adverse reaction was found in the treatment course. CONCLUSION: YBK can be used in the treatment of leukopenia caused by various factors, satisfactory in efficacy and safe in use.

Adolescent↗

PubMed2005

Immortalized rat astrocyte strain genetically modified by rat preprogalanin gene.

To construct an immortalized rat astrocyte strain genetically modified by rat preprogalanin gene (IAST/GAL) and detect its galanin (GAL) expression and secretion, a cDNA fragment of rat GAL in plasmid of pBS KS(+)-GAL was inserted into eukaryotic expression vector pcDNA3.1 (+) by DNA recombinant technology, then the restriction enzyme digestion and DNA sequencing were carried out to evaluate the recombinant. The pcDNA3.1 (+)-GAL and pcDNA3.1 (+) construct were transfected into immortalized rat astrocyte strain (IAST) by lipofectamine and the population of cells which stably integrated the construct was selected with 600 microg/mL G418. Individual clones were screened and expanded into clonal cell strains. Detection of Neo gene was used to validate the success of the transfection. Immunocytochemical staining, RT-PCR and radioimmunoassay were used to detect the expression and secretion level of GAL. The recombinant had been successfully constructed by restriction enzyme digestion and DNA sequencing. Detection of Neo gene showed that the pcDNA3.1 (+)-GAL and pcDNA3.1 (+) have been successfully transfected into IAST. After selection by using G418, IAST/GAL and IAST/Neo cell strains were obtained. IAST/GAL, IAST/Neo and IAST were immunostained positively for GAL, but the GAL average optical density of IAST/GAL was significantly higher than that of IAST/Neo and IAST (P< 0.01). The level of GAL mRNA expression and the supernatant concentration of GAL in cultured IAST/GAL were significantly higher than those of IAST and IAST/Neo (P<0.01), but no significant differences were found between the IAST and IAST/Neo (P>0.05). It was concluded that IAST/GAL strain was constructed successfully and it might provide a basis for the further study of pain therapy.

Animals↗

PubMed2005

The impact of physicians' health beliefs on colorectal cancer screening practices.

Primary-care physicians have significant influence on whether or not their patients participate in colorectal cancer screening (CRCS). This study explored the association of physicians' personal health beliefs, medical history, and personal participation in CRCS with their practice patterns regarding CRCS. Perceived personal risk for colorectal cancer (CRC) was associated with compliance with American Cancer Society (ACS) guidelines for CRCS for their patients (P = 0.03). For physicians at low risk for CRC, their perception of the seriousness of CRC was significantly associated with compliance (P = 0.047). For physicians at, at least, average risk for CRC, personal participation in CRCS did not predict whether they recommend CRCS to their patients. Efforts to improve physicians' understanding about their own susceptibility to CRC and the seriousness of CRC may improve their compliance with making recommendations for CRCS to their patients and may improve their participation in CRCS.

Attitude of Health Personnel↗

PubMed2005

Persistent and recurrent cervical dysplasia after loop electrosurgical excision procedure.

OBJECTIVE: Our objective was to determine whether demographic, colposcopic, and pathologic variables are predictive of recurrent cervical dysplasia. STUDY DESIGN: A retrospective review of patients who underwent loop electrosurgical excision procedure (LEEP) was performed. The medical records of the subjects were reviewed to identify demographic, pathologic, and procedural characteristics that predict recurrent dysplasia. RESULTS: A total of 514 subjects were identified who underwent LEEP between 1996 and 2003. Multivariate analysis revealed that advanced age, immunosuppression, and a positive endocervical margin were associated with recurrent dysplasia. CONCLUSION: Demographic and pathologic data can be used to predict the risk of recurrence of cervical dysplasia after LEEP.

Aging↗

PubMed2005

MSurvPow: a FORTRAN program to calculate the sample size and power for cluster-randomized clinical trials with survival outcomes.

Manatunga and Chen [A.K. Manatunga, S. Chen, Sample size estimation for survival outcomes in cluster-randomized studies with small cluster sizes, Biometrics 56 (2000) 616-621] proposed a method to estimate sample size and power for cluster-randomized studies where the primary outcome variable was survival time. The sample size formula was constructed by considering a bivariate marginal distribution (Clayton-Oakes model) with univariate exponential marginal distributions. In this paper, a user-friendly FORTRAN 90 program was provided to implement this method and a simple example was used to illustrate the features of the program.

Cluster Analysis↗

PubMed2005

Spectroscopy, NMR and DFT studies on molecular recognition of crown ether bridged chiral heterotrinuclear salen Zn(II) complex.

A barium-containing crown ether bridged chiral heterotrinuclear salen Zn(II) complex BaZn2L(ClO4)2, where L is a folded dinuclear chiral (R,R)-salen ligand, has been synthesized and characterized by elemental analysis, 1H NMR, UV-vis, IR, circular dichroism (CD) spectra, and mass spectra. As a folded dinuclear chiral host, its recognition with achiral guests (imidazole derivatives), rigid bidentate guest (1,4-diazobicyclo[2,2,2]octane, DABCO) and chiral guests (amino acid methyl esters) was investigated by means of UV-vis spectrophotometric titration, CD spectra. The association constants of D-amino acid methyl esters are found to be higher than those of their L-enantiomer. The sandwich-type binding of BaZn2L(ClO4)2-DABCO supramolecular assembly was specially studied via 1H NMR titration and 1H ROESY. To understand the recognition on molecular level, density functional theory (DFT) calculations on B3LYP/LanL2DZ were performed on the minimal energy conformations of host, guests, and host-guest complexes. The minimal energy conformations were obtained by molecular mechanics (MM) optimization and molecular dynamics (MD) simulation. The results of single point energy, HOMO energy, and charges transfer were analyzed. The results of theoretical calculations are in good agreement with the experimental data.

Barium↗

PubMed2005

Coronavirus phylogeny based on a geometric approach.

A novel coronavirus has been identified as the cause of the outbreak of severe acute respiratory syndrome (SARS). Previous phylogenetic analyses based on sequence alignments show that SARS-CoVs form a new group distantly related to the other three groups of previously characterized coronaviruses. In this paper, a geometric approach based on the Z-curve representation of the whole genome sequence is proposed to analyze the phylogenetic relationships of coronaviruses. The evolutionary distances are obtained through measuring the differences among the three-dimensional Z-curves. The Z-curve is approximately described by its geometric center and the associated three eigenvectors, which indicate the center position and the trend of the Z-curve, respectively. Although some information is lost due to the approximate description of the Z-curve, the phylogenetic tree constructed based on these parameters is consistent with those of previous analyses. The present method has the merits of simplicity and intuitiveness, but it is still in its premature stage. Because the phylogenetic relationships are inferred from the whole genome, instead of some individual genes, the present method represents a new direction of phylogeny study in the post-genome era.

Algorithms↗

PubMed2005

Cervical dysplasia in adolescents.

BACKGROUND: Although the incidence of cervical dysplasia in adolescents is increasing, a paucity of data exists regarding the outcomes of adolescents with Pap test abnormalities. We determined the natural history and outcome of adolescents with low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL). METHODS: A review of all women aged 18 years or younger with a cytologic diagnosis of LSIL or HSIL between 1997 and 2003 was performed. Follow-up cytologic and histologic samples were evaluated. The most significant abnormality was recorded for each patient. Rates of regression, persistence, and progression were calculated. RESULTS: A total of 646 adolescents were identified. Follow-up was available for 477 teenagers with LSIL and for 55 with HSIL. Among adolescents with LSIL, 146 (35%) had negative follow-up. Low-grade abnormalities (atypical squamous cells of undetermined significance, LSIL, and cervical intraepithelial neoplasia grade 1) were seen in 199 (47%), whereas high-grade abnormalities were documented in 77 (18%). After 36 months, 62% had regressed, whereas 31% had progressive dysplasia. For the HSIL cohort, negative follow-up was documented in 12 (21.8%) adolescents, and 15 (27.3%) had low-grade abnormalities, whereas more than one half (50.9%) were found to have a high-grade abnormality. At 36 months, 31% of HSIL subjects had progressed to cervical intraepithelial neoplasia 3. CONCLUSION: Adolescents with LSIL and HSIL cytology are at significant risk for progression to high-grade cervical abnormalities. The rate of development of high-grade cervical abnormalities in adolescents is similar to adults. Adolescents with cytologic abnormalities mandate close follow-up. LEVEL OF EVIDENCE: II-3.

Adolescent↗

PubMed2005

Caspase inhibition enhances ischemic tolerance of fasciocutaneous flaps.

OBJECTIVES/HYPOTHESIS: To demonstrate the significance of apoptosis in ischemia-reperfusion injury in revascularized fasciocutaneous flaps and test the hypothesis that pharmacologic inhibition of caspases prolongs the allowable primary ischemia time of these flaps. STUDY DESIGN: Animal study using the epigastric flap in adult male Sprague-Dawley rats. METHODS: Fifty-nine rats were treated with the caspase inhibitor (Q-VD-OPH) reconstituted in dimethylsulfoxide (DMSO) (n = 20, 8 mg/kg:0.8 mL/kg), DMSO alone (n = 19, 0.8 mL/kg), or saline (n = 20, 0.8 mL/kg). Treatment was given as a single intraperitoneal injection 30 minutes before starting primary ischemia. Epigastric flaps were subjected to increasing ischemia times followed by reperfusion. The flaps were harvested and analyzed 7 days later, and viability was assessed. Probit statistical analysis was used to determine the critical ischemia time. This was defined as the time point when 50% of the flaps in each group were expected to survive. RESULTS: The calculated critical ischemia times were 8.92 hours (95% confidence interval 7.19-10.47 h) for the saline group, 16.35 hours (95% confidence interval 11.82-19.89 h) for the DMSO group, and 21.73 hours (95% confidence interval 19.39-25.37 h) for the DMSO with Q-VD-OPH group. These differences were significantly different from each other. CONCLUSIONS: Pretreatment of fasciocutaneous flaps with a free radical scavenger alone or in combination with a caspase inhibitor significantly increases the flap's tolerance of primary ischemia. The added benefit of the caspase inhibitor suggests that apoptosis plays an important role in ischemia-reperfusion injury in soft tissue flaps.

Animals↗

PubMed2005

PSIST: indexing protein structures using suffix trees.

Approaches for indexing proteins, and for fast and scalable searching for structures similar to a query structure have important applications such as protein structure and function prediction, protein classification and drug discovery. In this paper, we developed a new method for extracting the local feature vectors of protein structures. Each residue is represented by a triangle, and the correlation between a set of residues is described by the distances between Calpha atoms and the angles between the normals of planes in which the triangles lie. The normalized local feature vectors are indexed using a suffix tree. For all query segments, suffix trees can be used effectively to retrieve the maximal matches, which are then chained to obtain alignments with database proteins. Similar proteins are selected by their alignment score against the query. Our results shows classification accuracy up to 97.8% and 99.4% at the superfamily and class level according to the SCOP classification, and shows that on average 7.49 out of 10 proteins from the same superfamily are obtained among the top 10 matches. These results are competitive with the best previous methods.

Algorithms↗

PubMed2005

Toll-like receptor and heme oxygenase-1 signaling in hepatic ischemia/reperfusion injury.

Ischemia/reperfusion injury (IRI) represents the major problem in clinical liver transplantation. We have shown that toll-like receptor 4 (TLR4) signaling is specifically required in initiating antigen-independent IRI leading to liver inflammation, whereas local induction of anti-oxidant heme oxygenase-1 (HO-1) is cytoprotective. This study analyzes in vivo interactions between HO-1 and sentinel TLR system in the pathophysiology of liver IRI. Using a 90-min lobar warm ischemia model, wild type (WT), TLR4 KO/mutant and TLR2 KO mice were first assessed for the severity of hepatocellular damage at 6 h postreperfusion. Unlike in WT or TLR2-deficient mice, disruption/absence of TLR4 pathway reduced IRI, as manifested by liver function (serum alanine aminotransferase levels), histology (Suzuki's scores), neutrophil infiltration (myeloperoxidase activity) and local/systemic TNF-alpha production (mRNA/protein levels). Moreover, defective TLR4 but not TLR2 signaling increased mRNA/protein HO-1 expression. In contrast, tin protoporphyrin-mediated HO-1 inhibition restored hepatic damage in otherwise IRI-resistant TLR4 mutant/KO mice. CoPP-induced HO-1 overexpression ameliorated hepatic damage in IRI-susceptible TLR2 KO mice, comparable with WT controls, and concomitantly diminished TLR4 levels. In conclusion, this study highlights the importance of cross talk between HO-1 and TLR system in the mechanism of hepatic IRI. Hepatic IRI represents a case for innate immunity in which HO-1 modulates proinflammatory responses that are triggered via TLR4 signaling, a putative HO-1 repressor.

Animals↗

PubMed2005

Detection of nucleolar organizer and mitochondrial DNA insertion regions based on the isochore map of Arabidopsis thaliana.

Eukaryotic genomes are composed of isochores, i.e. long sequences relatively homogeneous in GC content. In this paper, the isochore structure of Arabidopsis thaliana genome has been studied using a windowless technique based on the Z curve method and intuitive curves are drawn for all the five chromosomes. Using these curves, we can calculate the GC content at any resolution, even at the base level. It is observed that all the five chromosomes are composed of several GC-rich and AT-rich regions alternatively. Usually, these regions, named 'isochore-like regions', have large fluctuations in the GC content. Five isochores with little fluctuations are also observed. Detailed analyses have been performed for these isochores. A GC-rich 'isochore-like region' and a GC-isochore in chromosome II and IV, respectively, are the nucleolar organizer regions (NORs), and genes located in the two regions prefer to use GC-ending codons. Another GC-isochore located in chromosome II is a mitochondrial DNA insertion region, the position and size of this region is precisely predicted by the current method. The amino acid usage and codon preference of genes in this organellar-to-nuclear transfer region show significant difference from other regions. Moreover, the centromeres are located in GC-rich 'isochore-like regions' in all the five chromosomes. The current method can provide a useful tool for analyzing whole genomic sequences of eukaryotes.

AT Rich Sequence↗

PubMed2005

Human immunodeficiency virus type 1 env clones from acute and early subtype B infections for standardized assessments of vaccine-elicited neutralizing antibodies.

Induction of broadly cross-reactive neutralizing antibodies is a high priority for AIDS vaccine development but one that has proven difficult to be achieved. While most immunogens generate antibodies that neutralize a subset of T-cell-line-adapted strains of human immunodeficiency virus type 1 (HIV-1), none so far have generated a potent, broadly cross-reactive response against primary isolates of the virus. Even small increments in immunogen improvement leading to increases in neutralizing antibody titers and cross-neutralizing activity would accelerate vaccine development; however, a lack of uniformity in target strains used by different investigators to assess cross-neutralization has made the comparison of vaccine-induced antibody responses difficult. Thus, there is an urgent need to establish standard panels of HIV-1 reference strains for wide distribution. To facilitate this, full-length gp160 genes were cloned from acute and early subtype B infections and characterized for use as reference reagents to assess neutralizing antibodies against clade B HIV-1. Individual gp160 clones were screened for infectivity as Env-pseudotyped viruses in a luciferase reporter gene assay in JC53-BL (TZM-bl) cells. Functional env clones were sequenced and their neutralization phenotypes characterized by using soluble CD4, monoclonal antibodies, and serum samples from infected individuals and noninfected recipients of a recombinant gp120 vaccine. Env clones from 12 R5 primary HIV-1 isolates were selected that were not unusually sensitive or resistant to neutralization and comprised a wide spectrum of genetic, antigenic, and geographic diversity. These reference reagents will facilitate proficiency testing and other validation efforts aimed at improving assay performance across laboratories and can be used for standardized assessments of vaccine-elicited neutralizing antibodies.

AIDS Vaccines↗

PubMed2005

Antigenicity and immunogenicity of a synthetic human immunodeficiency virus type 1 group m consensus envelope glycoprotein.

Genetic variation of human immunodeficiency virus (HIV-1) represents a major obstacle for AIDS vaccine development. To decrease the genetic distances between candidate immunogens and field virus strains, we have designed and synthesized an artificial group M consensus env gene (CON6 gene) to be equidistant from contemporary HIV-1 subtypes and recombinants. This novel envelope gene expresses a glycoprotein that binds soluble CD4, utilizes CCR5 but not CXCR4 as a coreceptor, and mediates HIV-1 entry. Key linear, conformational, and glycan-dependent monoclonal antibody epitopes are preserved in CON6, and the glycoprotein is recognized equally well by sera from individuals infected with different HIV-1 subtypes. When used as a DNA vaccine followed by a recombinant vaccinia virus boost in BALB/c mice, CON6 env gp120 and gp140CF elicited gamma interferon-producing T-cell responses that recognized epitopes within overlapping peptide pools from three HIV-1 Env proteins, CON6, MN (subtype B), and Chn19 (subtype C). Sera from guinea pigs immunized with recombinant CON6 Env gp120 and gp140CF glycoproteins weakly neutralized selected HIV-1 primary isolates. Thus, the computer-generated "consensus" env genes are capable of expressing envelope glycoproteins that retain the structural, functional, and immunogenic properties of wild-type HIV-1 envelopes.

Amino Acid Sequence↗

PubMed2005

Heterogeneous effects of tissue inhibitors of matrix metalloproteinases on cardiac fibroblasts.

The balance between matrix metalloproteinases (MMPs) and their natural inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), plays a critical role in cardiac remodeling. Although a number of studies have characterized the pathophysiological role of MMPs in the heart, very little is known with respect to the role of TIMPs in the heart. To delineate the role of TIMPs in the heart we examined the effects of adenovirus-mediated overexpression of TIMP-1, -2, -3, and -4 in cardiac fibroblasts. Infection of cardiac fibroblasts with adenoviral constructs containing human recombinant TIMP (AdTIMP-1, -2, -3, and -4) provoked a significant (P < 0.0001) 1.3-fold in increase in bromodeoxyuridine (BrdU) incorporation. Similarly, treatment of cardiac fibroblasts with AdTIMP-1-, -2-, -3-, and -4-conditioned medium led to a 1.2-fold increase in BrdU incorporation (P < 0.0001) that was abolished by pretreatment with anti-TIMP-1, -2, -3, and -4 antibodies. The effects of TIMPs were not mimicked by treating the cells with RS-130830, a broad-based MMP inhibitor, suggesting that the effects of TIMPs were independent of their ability to inhibit MMPs. Infection with AdTIMP-1, -2, -3, and -4 led to a significant increase in alpha-smooth muscle actin staining, consistent with TIMP-induced phenotypic differentiation into myofibroblasts. Finally, infection with AdTIMP-2 resulted in a significant increase in collagen synthesis, whereas infection with AdTIMP-3 resulted in a significant increase in fibroblast apoptosis. TIMPs exert overlapping as well as diverse effects on isolated cardiac fibroblasts. The observation that TIMPs stimulate fibroblast proliferation as well as phenotypic differentiation into myofibroblasts suggests that TIMPs may play an important role in tissue repair in the heart that extends beyond their traditional role as MMP inhibitors.

Actins↗

PubMed2005

Phosphodiesterase 5 inhibitor, zaprinast, selectively increases cerebral blood flow in the ischemic penumbra in the rat brain.

BACKGROUND: Guanosine 3', 5'-cyclic monophosphate (cGMP) acts as a relaxant second messenger in the cerebral vessels. cGMP-specific phosphodiesterase type 5 (PDE5) inhibitor increases intracellular cGMP levels. This study investigated the effect of the PDE5 inhibitor on the ischemic brain. METHODS: Regional cerebral blood flow (rCBF), cGMP concentration, and infarction volume were measured in the rat middle cerebral artery occlusion model. Ten minutes after ischemia, the animals received an intravenous (i.v.) infusion of vehicle (phosphate-buffered saline), PDE5 inhibitor, zaprinast (10 mg/kg), or nitric oxide donor, S-nitroso-N-acetyl-penicillamine (SNAP, 100 microg/kg). rCBF was measured continuously by laser-Doppler flowmetry in the ischemic penumbra of the ischemic and contralateral sides under continuous blood pressure monitoring. cGMP concentrations were determined using the enzyme immunoassay and infarct volumes were estimated by 2,3,5-triphenyltetrazolium chloride staining. RESULTS: The administration of zaprinast significantly increased rCBF in the ischemic brain compared with the pre-drug control value despite the decreased mean blood pressure, whereas it did not affect rCBF in the contralateral side. The cGMP concentration was significantly higher in the ischemic cortex compared with the contralateral side. SNAP infusion increased the cGMP concentration in the bilateral cortices to a similar extent. The volume of cerebral infarction was significantly decreased by zaprinast administration. CONCLUSIONS: The PDE5 inhibitor zaprinast may selectively increase CBF in the ischemic brain via increased cGMP levels, thus providing a new strategy against acute cerebral infarction.

Analysis of Variance↗

PubMed2005

Power and sample size for clinical trials when efficacy is required in multiple endpoints: application to an Alzheimer's treatment trial.

BACKGROUND: When the efficacy of a treatment in a randomized controlled trial is required for multiple primary endpoints, trial design and analysis differ from trial requiring efficacy in only one of the multiple endpoints. METHODS: We consider a two-arm clinical trial requiring efficacy analysis for multiple primary endpoints, formulating the appropriate null and alternative hypotheses for the test of treatment efficacy. We study the significance level/statistical power of an intersection-union test (IUT) in this situation. We compare IUT with the intuitive approach (selecting the maximum sample size over those obtained from testing individual primary endpoints one by one) for determination of sample size. RESULTS: The proposed IUT reserves the same Type I error rate as shared by all endpoint-specific tests. The statistical power of the proposed IUT is no more than the minimum from the individual tests. The maximum sample size from multiple endpoint-specific tests is often inadequate for the test of treatment efficacy, especially when the standardized effect sizes are similar. Finally, the IUT can be applied to Alzheimer's disease treatment trials in which two primary endpoints are typically used. CONCLUSIONS: The IUT is a valid method for use in the design and analysis of clinical trials requiring efficacy at multiple primary endpoints.

Alzheimer Disease↗

PubMed2005

Detection of HIV-2 by PCR.

Genomes of human immunodeficiency virus type 2 (HIV-2), like those of HIV-1 or other retroviruses, are highly variable. These genetic variants have been classified into seven genetic subtypes. The average genetic divergence between different subtypes is about 20% in the gag gene, which is higher than those among HIV-1 group M subtypes. The current serological tests cannot distinguish the different subtypes from one another. To understand genetic variation, evolution, and subtype distribution of HIV-2, polymerase chain reaction (PCR) technology has been widely used. The PCR products that are amplified from highly conserved regions among all subtypes can be either cloned into plasmid vectors for sequence analysis or directly sequenced without a cloning step. Phylogenetic analysis of newly obtained sequences with reference sequences can determine the subtype classification or identify new subtypes if the sequences do not belong to any known subtypes.

DNA, Viral↗