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Biomedical subjects

G Peng

Publications and source records attributed to G Peng.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Detection of C gene mutation strain in vertical transmission of hepatitis B virus and its significance].

OBJECTIVE: This study aims at detecting C gene mutation strain in vertical transmission of hepatitis B virus (HBV). METHODS: HBV C gene nt 2,022 - 2,321 was directly sequenced. RESULTS: Homology of HBV nucleotide sequence and amino acid sequence in mothers, fathers and their fetus was 100%. Mutation of 2,189 and 2,288 nucleotide of C gene resulted in substitution at the 97th and 130th amino acids. CONCLUSION: C gene mutation strain is present in vertical transmission of HBV. Presence of mutation strain may be the cause of failure in vaccination.

Adult↗
PubMed1999

Disulfide structure of the pheromone binding protein from the silkworm moth, Bombyx mori.

Disulfide bond formation is the only known posttranslational modification of insect pheromone binding proteins (PBPs). In the PBPs from moths (Lepidoptera), six cysteine residues are highly conserved at positions 19, 50, 54, 97, 108 and 117, but to date nothing is known about their respective linkage or redox status. We used a multiple approach of enzymatic digestion, chemical cleavage, partial reduction with Tris-(2-carboxyethyl)phosphine, followed by digestion with endoproteinase Lys-C to determine the disulfide connectivity in the PBP from Bombyx mori (BmPBP). Identification of the reaction products by on-line liquid chromatography-electrospray ionization mass spectrometry (LC/ESI-MS) and protein sequencing supported the assignment of disulfide bridges at Cys-19-Cys-54, Cys-50-Cys-108 and Cys-97-Cys-117. The disulfide linkages were identical in the protein obtained by periplasmic expression in Escherichia coli and in the native BmPBP.

Amino Acid Sequence↗
PubMed1999

Co-infection with opportunistic pathogens promotes human immunodeficiency virus type 1 infection in macrophages.

Human immunodeficiency virus type 1 (HIV-1) infection is dependent on susceptible host cells that express both CD4 and chemokine co-receptors. The co-receptor CCR5 is associated with primary infection by macrophage-tropic virus isolates, whereas CXCR4 is commonly associated with T cell- and dual-tropic viruses. Once infected, lymphocytes and macrophages may replicate HIV-1 or harbor latent virus, depending on environmental factors and cellular activation. Immune activation is often associated with viremia, which is consistent with enhanced infection and viral replication in activated cells harboring virus. In this regard, opportunistic infections activate the immune system with the detrimental sequelae of enhanced viral replication and viremia. Under these conditions, viral expansion extends beyond T cells to tissue macrophages, many of which are co-infected with opportunistic pathogens. The opportunistic infections promote macrophage susceptibility to HIV-1 through cytokine modulation and altered chemokine co-receptors, potential targets for intervention.

AIDS-Related Opportunistic Infections↗
PubMed1999

Evolution of vaginal Candida species recovered from human immunodeficiency virus-infected women receiving fluconazole prophylaxis: the emergence of Candida glabrata? Terry Beirn Community Programs for Clinical Research in AIDS (CPCRA).

The effect of fluconazole prophylaxis on the vaginal flora of 323 human immunodeficiency virus-infected women was evaluated in a multicenter, randomized, double-blind, placebo-controlled trial. Women with CD4 cell counts of < or = 300/mm3 received either 200 mg of fluconazole per week or placebo. Vaginal surveillance cultures were performed every 3 months. After a follow-up of 29 months, Candida albicans was recovered from 53% of patients receiving fluconazole and 68% of patients assigned placebo. Fluconazole was associated with a 50% reduction in the odds of being colonized with C. albicans but with higher rates for non-albicans Candida species. Candida glabrata was recovered from 40 women assigned fluconazole and 29 assigned placebo (relative odds, 1.96; 95% confidence interval, 0.98-3.94). Fluconazole had an early and persistent effect on the vaginal mycoflora, with the emergence of C. glabrata vaginal colonization within the first 6 months. The effect of fluconazole prophylaxis can be attributed to the reduction in vaginal C. albicans colonization; however, C. glabrata colonization rapidly supervened.

AIDS-Related Opportunistic Infections↗
PubMed1999

Finite-volume lattice Boltzmann method.

We present a finite-volume formulation for the lattice Boltzmann method (FVLBM) based on standard bilinear quadrilateral elements in two dimensions. The accuracy of this scheme is demonstrated by comparing the velocity field with the analytical solution of the Navier-Stokes equations for time dependent rotating Couette flow and Taylor vortex flow. To demonstrate the flexibility of the scheme, we have also simulated a modified rotating Couette flow, where the inner cylinder has an elliptical shape. The results agree with those obtained from the traditional marker-and-cell method. The FVLBM scheme is applicable to arbitrarily shaped two-dimensional regions, and thus the range of applicability of the lattice Boltzmann method has been significantly extended.

Journal Article↗
PubMed1999

Finite-volume lattice Boltzmann schemes in two and three dimensions.

Simple and practical finite-volume schemes for the lattice Boltzmann equation are derived in two and three dimensions through the application of modern finite-volume methods. The schemes use a finite-volume vortex-type formulation based on quadrilateral elements in two dimensions and trilinear hexahedral elements in three dimensions. It is shown that the schemes are applicable to domains with irregular boundaries of arbitrary shape in two and three dimensions.

Journal Article↗
PubMed1999

Kinetic model of phase separation in binary mixtures with hard mobile impurities.

We develop a mean-field rate-equation model for the kinetics of phase separation in binary mixtures with hard mobile impurities. For impurities preferentially wet by one of the components, the phase separation is arrested in the late stage. The "steady-state" domain size depends strongly on both the particle diffusion constant and the particle concentration. We compare theoretical results with the simulation data and find good qualitative agreement.

Journal Article↗
PubMed1999

[Detection of S-gene mutation strain in vertical transmission of HBV and its significance].

OBJECTIVE: To study S-gene mutation of hepatitis B virus (HBV) in its vertical transmission and its significance. METHODS: Nucleotides of S-gene NT451-660 of HBV were sequenced with dideoxy end termination technique in four female and six male carriers without HBV markers in their spouses and in their intrauterine infected fetuses. RESULTS: It was showed that homology of HBV nucleotide and amino acid sequences in the mothers, fathers and their fetuses was very high. Mutation at the sites 491, 494, 530, 546 and 581 of S-gene resulted in amino acid substitution at the sites 113, 114, 126, 131 and 143, respectively. Mutations at the sites 126 were detected in two pairs of mother or father and her or his fetuses and mutations at the sites 131 in four fetuses, respectively, including combined mutation at the site 143 in two fetuses. CONCLUSION: Strains with S-gene mutation, mainly at the sites 126, 131 and 143, could be found in HBV vertical transmissions, which could cause failure in HB vaccine immunization.

Adult↗
PubMed1999

[HBV transmission from father to foetus and HBV DNA in tissues outside the liver].

OBJECTIVE: To study the possibility of HBV Transmission from father to foetus and HBV DNA in tissues outside liver. METHODS: Paired sera were from 8 HBV man carriers whose wives were negative for HBVM and 8 foetuses who were infected with HBV in the womb. S gene nt 451-660 nucleotide, C gene nt 2,022-2,321 nucleotide were directly sequenced. RESULTS: The homology of HBV sequence between father and foetus was very high. The mutations of 491, 494, 530, 546 and 581 nucleotide in the S gene caused 113, 114, 126, 131 and 143 amino acid substitution. HBV DNA can be detected in the tissues outside liver of foetus. CONCLUSION: HBV transmission from father to foetus may be present. HBV DNA in tissues outside liver of foetus can be detected.

Adult↗
PubMed1999

[Measurement of cyclosporine A in whole blood by high performance liquid chromatography(HPLC)].

Whole blood was extracted by ether under base using cyclosporine D as internal standard. The extraction was evaporated and reconstituted. The interferences were further removed by hexane. The reconstitution was injected into a C18 reversed-phase column at 70 degrees C, which was eluted with a mobile phase of acetonitrite/methanol/water(60/10/30, v/v) at flow rate 1.6 ml.min-1 and monitored at 210 nm. Three levels of BIO-RAD cyclosporine A(whole blood) calibrator were measured, all the results were within expected range. The detection limit was 25 ng.ml-1. The linearity was at least within 50-1,000 ng.ml-1. Analytical recoveries were 99.6%-108.8%. The within-run cv and between-run CV were 7.2% and 9.3%, respectively.

Chromatography, High Pressure Liquid↗
PubMed1999

Loss of anterior chamber-associated immune deviation during normal pregnancy in primates.

PURPOSE: We recently found that loss of anterior chamber-associated immune deviation was associated with normal pregnancy in rabbits. The purpose of this study is to further investigate whether the same events occurred in nonhuman primates. METHODS: Mid-pregnant cynomolgus monkeys were randomly selected. Bovine serum albumin (BSA) was inoculated in anterior chamber of eyes of nonpregnant and mid-pregnant monkeys that were subsequently immunized with BSA in adjuvant. Delayed-type hypersensitivity (DTH) was assessed by skin challenge. RESULTS: Non-pregnant monkeys of intracameral BSA proved able to acquire antigen-specific suppression of delayed-type hypersensitivity. By contrast, inoculation of BSA to anterior chamber of pregnant monkeys abolished the DTH-suppression effect. CONCLUSIONS: This is the first demonstration in primates that loss of anterior chamber-associated immune deviation occurred during normal pregnancy. The fluctuations of systemic hormone levels during normal pregnancy might influence local immunoregulation within the eye.

Animals↗
PubMed1999

[The role of spleen in induction and maintenance of anterior chamber-associated immune deviation in different species of animals].

PURPOSE: The importance of the spleen to the induction of anterior chamber-associated immune deviation (ACAID) in mice has been known for some time. Removal of the spleen within the first 4 days of injecting antigen into anterior chamber can abolish immune deviation and result in immunity. The purpose of this study is to explore the role of spleen in ACAID in other different species of animals. METHODS: After splenectomy and sham-splenectomy, bovine serum albumin (BSA) as a soluble antigen was inoculated into the anterior chamber (AC) of different animals (rat, rabbit and monkey) respectively. Recipient animals were immunized with BSA and complete Freund's adjuvant. Delayed-type hypersensitivity (DTH) was assessed by skin challenge. The maintenance time of deviant immune response was evaluated in the fixed interval. RESULTS: All the animals with receiving intraocular antigen inoculation, both in splenectomized group and in sham-splenectomized group, did not display DTH reaction. In addition, the maintenance time of immune deviation in both groups after AC inoculation of antigen was not significantly different. In contrast, all the animals without receiving intraocular antigen inoculation, both in splenectomized group and in sham-sple-nectomized group, displayed positive DTH reaction. CONCLUSIONS: The spleen may not play an important role in the induction and maintenance of ACAID in rat, rabbit and monkey. These data suggest that as the evolution progresses, the function of spleen may be replaced by other lymphatic organs.

Animals↗
PubMed1998

Mycobacterium avium complex augments macrophage HIV-1 production and increases CCR5 expression.

Infection with HIV-1 results in pronounced immune suppression and susceptibility to opportunistic infections (OI). Reciprocally, OI augment HIV-1 replication. As we have shown for Mycobacterium avium complex (MAC) and Pneumocystis carinii, macrophages infected with opportunistic pathogens and within lymphoid tissues containing OI, exhibit striking levels of viral replication. To explore potential underlying mechanisms for increased HIV-1 replication associated with coinfection, blood monocytes were exposed to MAC antigens (MAg) or viable MAC and their levels of tumor necrosis factor alpha (TNFalpha) and HIV-1 coreceptors monitored. MAC enhanced TNFalpha production in vitro, consistent with its expression in coinfected lymph nodes. Using a polyclonal antibody to the CCR5 coreceptor that mediates viral entry of macrophage tropic HIV-1, a subset of unstimulated monocytes was shown to be CCR5-positive by fluorescence-activated cell sorter analysis. After stimulation with MAg or infection with MAC, CCR5 expression was increased at both the mRNA level and on the cell surface. Up-regulation of CCR5 by MAC was not paralleled by an increase in the T cell tropic coreceptor, CXCR4. Increases in NF-kappaB, TNFalpha, and CCR5 were consistent with the enhanced production of HIV-1 in MAg-treated adherent macrophage cultures as measured by HIV-1 p24 levels. Increased CCR5 was also detected in coinfected lymph nodes as compared with tissues with only HIV-1. The increased production of TNFalpha, together with elevated expression of CCR5, provide potential mechanisms for enhanced infection and replication of HIV-1 by macrophages in OI-infected cells and tissues. Consequently, treating OI may inhibit not only the OI-induced pathology, but also limit the viral burden.

AIDS-Related Opportunistic Infections↗
PubMed1998

Sexually transmitted infections in women infected with the human immunodeficiency virus. Terry Beirn Community Programs for Clinical Research on AIDS (CPCRA).

BACKGROUND AND OBJECTIVES: Limited prospective data are available on sexually transmitted infections (STIs) among HIV-infected patients. The incidence and predictors of STIs were assessed among HIV-infected women enrolled in a clinical trial. STUDY DESIGN: Prospective cohort of 323 women. RESULTS: Sixty-five percent had at least one STI based on history and/or examination at baseline. Most conditions identified at baseline were based on patient history; only 10 of 123 women with no history of an STI (8.1%) had one identified upon examination. During a median follow-up of 2.1 years, 25% developed a new/recurrent STI. Being African-American (odds ratio [OR] = 4.22, 95% confidence interval [CI]: 1.45-12.26), reporting sex with an intravenous drug user as an HIV risk behavior (OR = 2.29, 95% CI: 1.34-3.92), and a history/presence of STIs at baseline (OR = 1.79, 95% CI: 1.01-3.19) were factors associated with significantly increased risk of STI's. CONCLUSIONS: A substantial proportion of women developed new STIs during the course of the clinical trial. Prevention efforts should be emphasized among high risk HIV-infected patients.

Adult↗
PubMed1998

[Separation and determination of carotenoids in Fructus lycii by isocratic non-aqueous reversed-phase liquid chromatography].

High performance liquid chromatography using a non-aqueous reversed phase with isocratic elution of C18 columns is a powerful tool for investigating the carotenoid composition of Fructus Lycii. This paper compared the effect of different eluents on the separation of carotenoids. An optimum solvent system consisting of acetonitrile and methylene chloride is suitable for simultaneous separation of compounds from polar xanthophylls to nonpolar carotenoid esters. Ten carotenoids were separated from Fructus Lycii by using Shim-pack CLC-ODS column(150 mm x 6 mm i.d.) and mobile phase of acetonitrile/methylene chloride(60:42, V/V) with a flow rate of 1 mL/min. The eluates were monitored with UV/VIS detector at 456 nm. The method which permit direct analysis of carotenoid extracts without saponification in 30 min provides a true information of carotenoids composition in Fructus Lycii as they exist. Fructus Lycii contains 2952 micrograms/g of total carotenoids, but 98.6% of carotenoids are existed as esterified forms, zeaxanthin dipalmitate are accounted for 77.5% of the total carotenoide.

Carotenoids↗
PubMed1998

[The use of orthognathic surgery in the treatment of maxillofacial fractures].

35 cases with bony malunion following maxillofacial fractures had been treated successfully by orthognathic surgery technique. Mini-titanium plate had been used in the rigid internal fixation. The article introduced the surgical method and discussed some primary principals which should be paid attention during operation.

Adolescent↗