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Biomedical subjects

A Huang

Publications and source records attributed to A Huang.

At least 73 records · Page 4Linked to original sources
PubMed2001

Erythrocytic glutathione and plasma cysteine status of human immunodeficient patients.

Both deficient and normal blood levels of glutathione (GSH) and cysteine (Cys) have been reported in HIV patients, a discrepancy that has been attributed to different methodologies. The goal of this study was to apply our analytical method to this problem. Blood samples from HIV patients and healthy subjects were collected, immediately stabilized, and quantified using high performance liquid chromatography with dual electrochemical detection. The results showed that the erythrocytic GSH levels were the same in healthy subjects and in HIV patients regardless of their CD4 lymphocyte level. Only those with the lowest CD4 level plus opportunistic infections had supranormal [corrected] GSH concentrations (P < 0.001). GSH plus glutathione disulfide (GSSG) levels also were normal in patients. However, the Cys contents were higher in patients than in controls (P < 0.05). These findings demonstrated that HIV patients have normal erythrocytic GSH concentrations and supranormal Cys levels.

Adult↗
PubMed2001

Colorectal cancer surveillance post-surgery.

Current surveillance methods for detecting recurrence after apparently curative colorectal cancer resection are insensitive and have not been shown to significantly improve survival. New surveillance methods based on molecular, flow cytometric and immunohistochemical detection of small numbers of tumour cells may prove more sensitive in detecting early recurrent cancer and may improve outcome.

Biomarkers, Tumor↗
PubMed2001

Development and application of the serological assay for humoral immune response against duck hepatitis B virus.

OBJECTIVE: To develop a simple and specific assay for detection of humoral immune response in duck hepatitis B virus (DHBV) infected ducks. METHODS: Eighty serum samples were detected by ELISA for DHBsAg with prepared anti-preS 1H1 ascitic fluid and by PCR or dot blot hybridization for DHBV DNA. Thirty-two serum samples from experimentally infected 1-day-old ducks were assayed by ELISA for DHBcAb and DHBsAb. RESULTS: Of 66 PCR positive samples, 58 were positive for DHBsAg and 62 were positive for DHBV dot blot hybridization. Sensitivities of the two methods were 87.9% and 93.9%, respectively. Anti-DHBc was developed in 2/8 infected ducks at day 21 but negative after day 28. Anti-DHBs antibodies were negative throughout the infectious period. CONCLUSION: The application of DHBV infection and serological assay will be helpful to the study of kinetics of DHBV and humoral immune response of ducks against the virus.

Animals↗
PubMed2001

[Comparison of specific immune responses to duck hepatitis B virus in infected, immune, and uninfected ducks].

OBJECTIVE: To explore the factor in determining whether hepadnavirus infection is cleared or becomes chronic. METHODS: Experimental groups were established by inoculation with duck hepatitis B virus (DHBV) at different age and schedule. The kinetics of virus replication and the humoral and cell mediated immune response (CMI) by ducks acutely and chronically infected with, or immune to DHBV infection was measured. RESULTS: Infection of the adolescent animals with DHBV led to a transient viremia. The levels of anti-DHBs and anti-DHBc were higher in acutely infected group than in chronically infected group (P<0.05), but lower than in immune group (P<0.01). CMI analysis showed the response to DHBsAg and DHBcAg by peripheral blood mononuclear cells from acutely infected ducks (10 day pi) was stronger than that from chronically infected ones (P<0.05); however, the level of the response reduced over a period of 5 weeks. There were no differences regarding CMI response in acutely infected or immune ducks. CONCLUSIONS: The immune response especially antigen -specific immune response is the key factor in determining the outcome of the infection.

Animals↗
PubMed2001

[Influence of electroporation on the biological activities of primary rat hepatocytes].

OBJECTIVE: To investigate the influence of electroporation on the biological activities of primary rat hepatocyte and to optimize the electroporation conditions introducing foreign genes into hepatocytes. METHODS: A single-pulse procedure was performed at low voltage (220-400 V) but high capacitance (500-950 microF). Its influence on hepatocyte activities was detected by Trypan blue exclusion (TBE) and MTT analysis. Besides, ALB, ALT and LDH in the supernatants of hepatocytes were tested by biochemical assay. RESULTS: Little hepatocyte damage and high survival rate (>90%) was found from 36 hours till 9th day of culture. At 36th hour after electroporation, ALB, ALT and LDH in the supernatants of Group B (220V, 950 microF) and C (400 V, 950 microF) were higher than those of control group. Whereas TBE and MTT analysis failed to indicate the significant difference of cell viability between electroporation groups and control group. CONCLUSIONS: This electroporation procedure is one of the optimal choices to introduce foreign genes into primary rat hepatocytes.

Animals↗
PubMed2001

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Breast↗
PubMed2001

[Construction of a dicistronic expression plasmid vector containing double-valent hepatitis B surface gene].

OBJECTIVE: In order to enhance vaccine response, we constructed a dicistronic expression plasmid containing double HBsAg immunogenes. METHODS: At first, pcDNA3.1 plasmid vector was digested with NheI and EcoRI to get the coding sequence of the small (S) surface protein of HBV, then cloned into pCI-neo vector and named it pCI-S. By PCR amplification, the product of IRES-S was digested with SalI & BamHI, and cloned into pBluescript IIK+S to generate pBKS-IRES-S vector, then subcloned to the pCI-S plasmid to generate pCI-S-IRES-S, which is a dicistronic plasmid of double value HBsAg genes. RESULTS: Two plasmids we constructed were digested with related restriction nucleic enzymes. Sequence analysis of HBsAg and IRES-S gene did not reveal any mutation. CONCLUSIONS: The construction of dicistronic plasmid of divalue HBsAg immunogenes has been well cloned, which is convenient for further research on cell expression and gene immunization in animals.

Antigens, Viral↗
PubMed2001

[Experimental study on the effect of combination therapy with lamivudine and famciclovir against duck hepatitis B virus in vivo].

OBJECTIVE: To study the antiviral effect of combination therapy with the nucleoside analog lamivudine and famciclovir on duck hepatitis virus (DHBV) in vivo. METHODS: The Chongqing duck hepatitis B model was treated with lamivudine and famciclovir by intragastric administration for 4 weeks. DHBV DNA and DHBsAg in serum were observed by serum dot-blot hybridization and ELISA. ALT and AST in serum were also detected. Histological observation on the duck liver was done simultaneously. The trial was contrasted with a single acyclovir (ACV), famciclovir (FCV), or Lamivudine (3TC). RESULTS: Combination therapy with Lamivudine and famciclovir could significantly reduce the serum DHBV DNA level. After stopping the treatment for 1 week, serum DHBV DNA level did not return significantly. The change of DHBsAg was similar to DHBV DNA. The level of ALT, AST, and the features of liver histopathology in combination-treated ducks were not different from those in control ducks. CONCLUSIONS: The study confirms that combination therapy is superior to single antiviral agent in vivo for ducks with chronic DHBV carrier.

2-Aminopurine↗
PubMed2001

[Study on the replication of hepatitis B virus compared with that of duck hepatitis B virus in primary duck hepatocytes].

OBJECTIVE: By studying the replication of Hepatitis B virus (HBV) compared with that of Duck Hepatitis B virus (DHBV) in primary duck hepatocytes (PDH), we want to explore the host-specific regulating roles on the replication of HBV in hepatocytes from heterologous species. METHODS: PDH were transfected with complete HBV genome by electroporation (transfected group, 1.19 x 10(12) copies of linear HBV DNA/1 x 10(7) PDH) or infected with DHBV (infected group, 4 x 10(8) virions/1 x 10(7) PDH). 1, 3 and 5 days after transfection or infection, HBsAg, HBeAg and DHBsAg in the supernatant and lysate of PDH were measured with IMX System or ELISA. Meanwhile, replicative intermediates of HBV DNA and DHBV DNA were analyzed by Southern blotting and dot blotting. PDH electroporated only was used as control group. RESULTS: HBsAg in the lysates of transfected group were 15.24 (1 day), 14.55 (3 days) and 5.13 (5 days; P/N values, positive > or = 2.1), HBeAg all was negative (< 2.1), and both were negative in the supernatants of transfected group. DHBsAg in the supernatants of infected group were 14.6 (1 day), 31.53 (3 days) and 34.73(5 days; S/N values, positive > or = 2.1). Dot blotting revealed that both the total amount of HBV DNA in the transfected group and DHBV DNA in the infected group were strongly positive, whereas that of the control group was negative. Southern blot analysis of intracellular total DNA indicated that there are relaxed circular (RC), covalently closed circular (ccc) and single-stranded (SS) HBV DNA replicative intermediates in the transfected group, there was no integrated HBV DNA in the cellular genome, as the same as that of DHBV DNA in the infected group. Control groups were negative at all. CONCLUSION: Our results demonstrate that expression of HBV genes and production can occur in hepatocytes from nonmammalian species and strongly support the idea that HBV replication has no critical species-specificity, and yet hepatic-specific regulating factors could be essential for viral replication.

Animals↗
PubMed2000

Ascorbic acid enhances endothelial nitric-oxide synthase activity by increasing intracellular tetrahydrobiopterin.

Ascorbic acid enhances NO bioactivity in patients with vascular disease through unclear mechanism(s). We investigated the role of intracellular ascorbic acid in endothelium-derived NO bioactivity. Incubation of porcine aortic endothelial cells (PAECs) with ascorbic acid produced time- and dose-dependent intracellular ascorbic acid accumulation that enhanced NO bioactivity by 70% measured as A23187-induced cGMP accumulation. This effect was due to enhanced NO production because ascorbate stimulated both PAEC nitrogen oxide (NO(2)(-) + NO(3)(-)) production and l-arginine to l-citrulline conversion by 59 and 72%, respectively, without altering the cGMP response to authentic NO. Ascorbic acid also stimulated the catalytic activity of eNOS derived from either PAEC membrane fractions or baculovirus-infected Sf9 cells. Ascorbic acid enhanced bovine eNOS V(max) by approximately 50% without altering the K(m) for l-arginine. The effect of ascorbate was tetrahydrobiopterin (BH(4))-dependent, because ascorbate was ineffective with BH(4) concentrations >10 microm or in PAECs treated with sepiapterin to increase intracellular BH(4). The effect of ascorbic acid was also specific because A23187-stimulated cGMP accumulation in PAECs was insensitive to intracellular glutathione manipulation and only ascorbic acid, not glutathione, increased the intracellular concentration of BH(4). These data suggest that ascorbic acid enhances NO bioactivity in a BH(4)-dependent manner by increasing intracellular BH(4) content.

Animals↗
PubMed2000

Evidence for changing of cosmic ray composition between 10(17) and 10(18) eV from multicomponent measurements

The average mass composition of cosmic rays with primary energies between 10(17) and 10(18) eV has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases.

Journal Article↗
PubMed2000

Cloning and characterization of IL-17B and IL-17C, two new members of the IL-17 cytokine family.

IL-17 is a T cell-derived cytokine that may play an important role in the initiation or maintenance of the proinflammatory response. Whereas expression of IL-17 is restricted to activated T cells, the IL-17 receptor is found to be widely expressed, a finding consistent with the pleiotropic activities of IL-17. We have cloned and expressed two novel human cytokines, IL-17B and IL-17C, that are related to IL-17 ( approximately 27% amino acid identity). IL-17B mRNA is expressed in adult pancreas, small intestine, and stomach, whereas IL-17C mRNA is not detected by RNA blot hybridization of several adult tissues. No expression of IL-17B or IL-17C mRNA is found in activated T cells. In a survey of cytokine induction, IL-17B and IL-17C stimulate the release of tumor necrosis factor alpha and IL-1beta from the monocytic cell line, THP-1, whereas IL-17 has only a weak effect in this system. No induction of IL-1alpha, IL-6, IFN-gamma, or granulocyte colony-stimulating factor is found in THP-1 cells. Fluorescence-activated cell sorter analysis shows that IL-17B and IL-17C bind to THP-1 cells. Conversely, IL-17B and IL-17C are not active in an IL-17 assay or the stimulation of IL-6 release from human fibroblasts and do not bind to the human IL-17 receptor extracellular domain. These data show that there is a family of IL-17-related cytokines differing in patterns of expression and proinflammatory responses that may be transduced through a cognate set of cell surface receptors.

Amino Acid Sequence↗