Search PubMed⌕ Search

Biomedical subjects

Yuan Li

Publications and source records attributed to Yuan Li.

At least 91 records · Page 5Linked to original sources
PubMed2005

A study on methods of estimating the population size of men who have sex with men in Southwest China.

OBJECTIVE: To ascertain practical methods of estimating the population size of men who have sex with men (MSM) by field application. METHODS: Nine public places were selected, where men who have sex with men (MSM) frequented. Capture-recapture method and multiplier method were used to count the number of men who have sex with men (MSM) in the assigned places in 10 days. RESULTS: The population size estimated using multiplier method counted 877. Three estimates produced by capture-recapture method were 1408 (95% CI: 1116-1908), 1207 (95% CI: 932-1712) and 949 (95% CI: 757-1272), respectively. CONCLUSIONS: Multiplier method was easy and smooth in practice and produced highly reliable results, which yet was expensive. The application of capture-recapture method cost less in both time and funds, and the three results produced could verify each other, which was fit for the estimation.

China↗
PubMed2005

Morphine withdrawal enhances hepatitis C virus replicon expression.

We previously demonstrated that morphine enhances hepatitis C virus (HCV) replication in human hepatic cells. Here we describe the impact of morphine withdrawal (MW), a recurrent event during the course of opioid abuse, on HCV replicon expression in human hepatic cells. MW enhanced both viral RNA and protein expression in HCV replicon cells. Blocking opioid receptors by treatment with naloxone after morphine cessation (precipitated withdrawal, PW) induced greater HCV replicon expression than MW. Investigation of the mechanism responsible for MW- or PW-mediated HCV enhancement showed that both MW and PW inhibited the expression of endogenous interferon-alpha (IFN-alpha) in the hepatic cells. This down-regulation of intracellular IFN-alpha expression was due to the negative impact of MW or PW on IFN-alpha promoter activation and on the expression of IFN regulatory factor 7 (IRF-7), a strong transactivator of the IFN-alpha promoter. In addition, both MW and PW inhibited the anti-HCV ability of recombinant IFN-alpha in the hepatic cells. These in vitro observations support the concept that opioid abuse favors HCV persistence in hepatic cells by suppressing IFN-alpha-mediated intracellular innate immunity and contributes to the development of chronic HCV infection.

Cell Line↗
PubMed2005

Alcohol suppresses IL-2-induced CC chemokine production by natural killer cells.

BACKGROUND: Natural killer (NK) cells are a critical component of the host innate immune system. We investigated whether alcohol impairs NK cell function, particularly production of CC chemokines induced by interleukin (IL)-2, the natural ligands for CCR5 receptor. METHODS: Primary NK cells and NK cell line (YTS) were cultured with or without alcohol (10 to 80 mM) for three hours. The culture supernatants were then harvested and used to treat human peripheral blood monocyte-derived macrophages and a HeLa cell line, which expresses CD4, CCR5, and CXCR4 receptors (MAGI cells). CC chemokine expression by YTS and primary NK cells treated with or without alcohol was analyzed with the real-time RT-PCR and ELISA. [Ca(2)(+)]i and Western blot assays were used to determine calcium-mediated intracellular signaling pathway and NF-kappaB p65 expression. HIV strains (Bal and UG024) were used to infect macrophages and MAGI cells. In addition, ADA (macrophage-tropic strain) and murine leukemia virus (MLV) envelope-pseudotyped HIV infection was carried out in macrophages. HIV infectivity was determined by HIV reverse transcriptase (RT) and beta-galactosidase activity assays. RESULTS: Alcohol inhibited IL-2-induced CC chemokine (CCL3 and CCL4) expression by NK cells. Functional tests demonstrated that this reduced expression of CC chemokines was associated with diminished anti-HIV ability of NK cells. Alcohol also reduced the ability of NK cells to response to CCL3-mediated chemotaxis. Alcohol inhibited IL-2-induced NF-kappaB p65 protein expression and calcium mobilization by NK cells. CONCLUSIONS: Alcohol, through the inhibition of IL-2-induced NF-kappaB p65 protein expression and intracellular calcium mobilization, suppressed NK cell production of CC chemokines. This suppression of CC chemokine production was associated with diminished anti-HIV activity of NK cells. Thus, by inhibiting NK cell-mediated innate immunity against HIV, alcohol consumption may have a cofactor role in the immunopathogenesis of HIV disease.

Adult↗
PubMed2005

Toll-like receptor 4 detected in exocrine pancreas and the change of expression in cerulein-induced pancreatitis.

OBJECTIVES: To detect Toll-like receptor 4 (TLR4) expression and distribution in rat pancreas and the change of TLR4 expression in cerulein-induced pancreatitis (CIP). METHODS: Acute pancreatitis was induced by subcutaneous injections of cerulein at a total dose of 20 microg/kg. Immunohistochemistry (IHC) was used to detect and localize TLR4 in rat pancreas, and real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to quantitatively determine the expression of TLR4 mRNA in CIP. RESULTS: IHC showed the presence of TLR4 in rat pancreas, and its distribution was specifically localized to pancreatic ductal epithelium, vascular endothelium, and islet. No TLR4 staining was detected in exocrine acinar cells. Real-time RT-PCR results revealed low-level TLR4 mRNA expression in the rat pancreas, and the change of TLR4 in CIP only developed within the first 4 hours, which is a rapid up-regulation process that peaks at the first hour. TLR4 mRNA was sustained at baseline level from 4 to 24 hours. CONCLUSIONS: TLR4 protein was expressed in pancreas and localized to epithelial (pancreatic duct) or endothelial (vessels) tissues; TLR4 responded favorably to the inflammatory process, and the change of expression was characterized as a rapid up-regulation in the early stage of CIP.

Acute Disease↗
PubMed2005

Inactivation of the 20S proteasome in Streptomyces lividans and its influence on the production of heterologous proteins.

Proteasomes are self-compartmentalizing proteases first discovered in eukaryotes but also occurring in archaea and in bacteria belonging to the order Actinomycetales. In bacteria, proteasomes have so far no known function. In order to evaluate the influence of the 20S proteasome on the production of heterologous proteins by Streptomyces lividans TK24, the production of a number of heterologous proteins, including soluble human tumour necrosis factor receptor II (shuTNFRII) and salmon calcitonin (sCT), was compared with the wild-type TK24, a proteasome-deficient mutant designated PRO41 and a strain complemented for the disrupted proteasome genes (strain PRO41R). S. lividans cells lacking intact proteasome genes are phenotypically indistinguishable from the wild-type or the complemented strain containing functional proteasomes. Using the expression and secretion signals of the subtilisin inhibitor of Streptomyces venezuelae CBS762.70 (Vsi) for shuTNFRII and those of tyrosinase of Streptomyces antibioticus (MelC1) for the production of sCT, both proteins were secreted in significantly higher amounts in the strain PRO41 than in the wild-type S. lividans TK24 or the complemented strain PRO41R. However, the secretion of other heterologous proteins such as shuTNFRI was not enhanced in the proteasome-deficient strain. This suggests that S. lividans TK24 can degrade some heterologous proteins in a proteasome-dependent fashion. The proteasome-deficient strain may therefore be useful for the efficient production of these heterologous proteins.

Bacterial Proteins↗
PubMed2005

A clinical study of 674 patients with oral lichen planus in China.

BACKGROUND: Oral lichen planus (OLP) is a chronic inflammatory disease with different clinical presentations that can be classified as reticular, atrophic or erosive. Although OLP is a relatively common disorder, the reports comprising large numbers of OLP patients with specific character are lacking in the literature. The purpose of this paper was to describe the clinical characteristics of OLP in 674 Chinese patients. METHODS: A total of 674 charts of patients with histologically confirmed OLP were collected from Stomatological Hospital of Wuhan University between 1963 and 2003. RESULTS: Of the 674 patients, 65.9% were women and 34.1% were men. The most common clinical presentation was the reticular type (51.3%), and symptomatic OLP was noted in 67.5% of the patients, mainly in those with the erosive form. The erosive presentations showed significantly longer duration, more sites affected and a much greater old patients predominance than reticular or atrophic ones. About 90.9% of the patients had multiple oral sites of involvement and isolated lower lip lichen planus were observed in 60 cases (8.9%) and isolated gingiva lichen in only one case (0.2%). Skin involvement of lichen planus was found in 11.4% of patients. No statistically significant differences could be identified between OLP and diabetes, cardiovascular disease, smoking or alcohol use. Precipitating factors that resulted in an exacerbation of the disease were frequently noted and included foods, stress, dental cusp and poor oral hygiene. The transformation of OLP into malignancy was observed in four patients at sites previously diagnosed by clinical examination as erosive or atrophic lichen planus. CONCLUSIONS: Patients with OLP in China usually present with distinctive clinical morphology and characteristic distribution and few may display lesions with a confusing array of forms mimicking other diseases. A long time follow up is of utmost importance to detect its malignant transformation.

Age Distribution↗
PubMed2005

Simian immunodeficiency virus integration preference is similar to that of human immunodeficiency virus type 1.

Simian immunodeficiency virus (SIV) is a useful model for studying human immunodeficiency virus (HIV) pathogenesis and vaccine efficacy. As with all other retroviruses, integration is a necessary step in the replication cycle of SIV. The location of the retrovirus integration site is known to impact on viral gene expression, establishment of viral latency, and other aspects of the replication cycle of a retrovirus. In this study, 148 SIV provirus integration sites were sequenced and mapped in the human genome. Our analysis showed that SIV integration, like that of HIV type 1 (HIV-1), exhibited a strong preference for actively transcribed regions in the genome (A. R. Schroder et al., Cell 110:521-529, 2002) and no preference for the CpG islands or transcription start sites, in contrast to observations for murine leukemia virus (X. Wu et al., Science 300:1749-1751, 2003). The parallel integration target site preferences of SIV and HIV-1 suggest that these lentiviruses may share similar mechanisms for target site selection and that SIV serves as an accurate model of HIV-1 with respect to integration.

Cell Line↗
PubMed2005

Weak palindromic consensus sequences are a common feature found at the integration target sites of many retroviruses.

Integration into the host genome is one of the hallmarks of the retroviral life cycle and is catalyzed by virus-encoded integrases. While integrase has strict sequence requirements for the viral DNA ends, target site sequences have been shown to be very diverse. We carefully examined a large number of integration target site sequences from several retroviruses, including human immunodeficiency virus type 1, simian immunodeficiency virus, murine leukemia virus, and avian sarcoma-leukosis virus, and found that a statistical palindromic consensus, centered on the virus-specific duplicated target site sequence, was a common feature at integration target sites for these retroviruses.

Base Sequence↗
PubMed2005

[Expression and significance of epidermal growth factor receptor variant type III in hepatocellular carcinoma].

BACKGROUND & OBJECTIVE: Many evidences show that epidermal growth factor receptor variant type III (EGFRvIII) plays an important role in initiation and progression of various cancers. But the relationship between EGFRvIII and hepatocellular carcinoma (HCC) is unclear. This study was to explore the expression and significance of EGFRvIII in human HCC tissues. METHODS: Immunohistochemical staining (IHC) was used to detect the expression of EGFRvIII in 55 specimens of HCC tissues and their adjacent non-cancerous liver tissues. RESULTS: Positive rate of EGFRvIII in HCC tissue was significantly higher than that in adjacent non-cancerous liver tissue [61.8% (34/55) vs. 38.2% (21/55), P < 0.05]. Positive rate of EGFRvIII in HCC tissue was significantly correlated with clinical stage,portal vein tumor thrombus,presence of extrahepatic metastasis, tumor recurrence, and the diameter of tumor, but not correlated with the number of foci, serum alpha-fetoprotein (AFP) level, serum HBsAg status, tumor differentiation, and cirrhosis in adjacent liver tissue. CONCLUSION: EGFRvIII is over-expressed in human HCC tissues, and relates to progression and recurrence of HCC.

Adult↗
PubMed2005

[Screening and construction of recombinant BCG strains expressing the Ag85B-ESAT6 fusion protein].

OBJECTIVE: To screen and construct recombinant BCG strains which express the Ag85B-ESAT6 fusion protein. METHODS: The heat shock protein 60 (Hsp60) and the alpha-ss signal peptide encoding sequence were amplified by PCR from Mycobacterium tuberculosis H(37)Rv and cloned into E. coli/Mycobacteria shuttle vector-pOLYG. The resulting expression vector was named pDE22, and then ag85b and esat6 genes were cloned into pDE22 at different sites. The resulting recombinant plasmids Ag85B-ESAT6 and ESAT6-Ag85 were electroporated into BCG. Positive clones were screened by hygromycin resistance and confirmed by PCR. Recombinant BCG culture supernatants were collected and analyzed by SDS-PAGE and Western blot. RESULTS: Two recombinant BCG strains were obtained, which secreted the 37,000 fusion protein in their culture supernatant, which was confirmed by Western blot with specific immune serum against Ag85B and ESAT6. CONCLUSIONS: Recombinant BCG strains expressing Ag85B and ESAT6 fusion proteins of Mycobacterium tuberculosis were constructed. They may serve as new vaccine candidates for preventing tuberculosis.

Acyltransferases↗
PubMed2005

[The effects of rBCG expressing Der p2 in the form of lipoprotein on murine immune response].

AIM: To investigate the effects of rBCG vaccination containing foreign antigen Der p2 in the form of lipoprotein on murine immune response. METHODS: 6 to 8 weeks old and newborn BALB/c mice were vaccined intraperitoneally with 10(6) CFU rBCG or BCG. At the same time, the control group was injected with saline. Six weeks later, all animals were injected with Der p2 (20 microg). After two weeks later, the concentrations of IL-4 and IFN-gamma in the serum and splenocyte culture supernatant (STLCS) were determined by ELISA, and Th subgroups were determined by double fluorescent staining and flow cytometry. RESULTS: After vaccination, the serum and STLCS from both rBCG-immunized and BCG-immunized group of adult and newborn BALB/c mice had significantly higher level of IFN-gamma and lower level of IL-4 than those from control groups. Besides, there was the larger percentage of CD4 (+) IFN-gamma (+) cells in spleen from rBCG-vaccined and BCG-vaccined mice than that from control group. However, the percentage of CD4 (+) IL-4 (+) cells in spleen cells from rBCG-vaccined and BCG-vaccined group was lower than that from control group. Moreover, the level of IFN-gamma in STLCS from rBCG-immunized was significantly higher, compared with that from BCG-immunized mice. At the same time, the percentage of CD4 (+) IFN-gamma (+) cells in spleen from rBCG-vaccined mice was larger than that from BCG-vaccined group. CONCLUSION: Both rBCG and BCG could stimulate Th1 predominant immune response, when injected intraperitoneally into adult or newborn BALB/c mice, The Der p2 expressed on the cell wall of BCG can work as the component of BCG and be recognized by the immune system of mice, therefore stimulates Der p2-specific Th1 predominant immune response. These data indicate that recombinant BCG-expressing antigens can be used as the antigen-specific vaccines against allergic diseases by regulating the balance of Th1/Th2.

Animals↗
PubMed2005

[A study on acquired immune deficiency syndrome related behaviors in male clients of female sex workers].

OBJECTIVE: To study the socio-demographic characteristics, acquired immune deficiency syndrome (AIDS) related behaviors of male clients of female sex workers and their determinants. METHODS: Contacting subjects through 5 ways including volunteers of female sex workers (FSWs), sexually transmitted disease (STD) clinics, long-distance bus stations, long-distance cargo station while adopting methods as snowballing, employing an anonymous questionnaire. Data was analyzed by logistic regression analysis. RESULTS: (1) The majority of clients were 25-45 years old, married and of junior high school or above educational levels; (2) Among male clients of FSWs, numbers of having had commercial sexual intercourse was between 1 to 240, averaged 24 in the previous year. It significantly related to their occupation and the experience of their friends or colleagues who ever visited female sex workers; (3) 27.98% of them used condom every time during commercial sexual intercourse, which significantly related to the score of knowledge on AIDS, concourse of sex intercourse and inhabitation; (4) 28.36% of them had ever contracted STD, which significantly related to the frequency of commercial sexual intercourse in the previous year, risk awareness of being infected with human immunodeficiency virus, and frequency of condom use during commercial sexual intercourse. CONCLUSION: The proportion of always using condom was low among male clients of FSWs, and had had STDs. And it's necessary for active and specific intervention programs to them.

Acquired Immunodeficiency Syndrome↗
PubMed2005

[Treatment of polycystic ovarian syndrome with anovulatory infertility by ultrasound-guided immature follicle aspiration].

OBJECTIVE: To investigate the effect of ultrasound-guided immature follicle aspiration (IMFA) on polycystic ovarian syndrome (PCOS) in women with anovulatory infertility, such as the endocrinology of the patients and the basic follicles number in the ovaries, and to observe the ovarian response to human menopausal gonadotropin (hMG) stimulation and pregnancy after the therapy. METHODS: Seventy-one PCOS patients were involved in this trial, and divided into 2 groups. Thirty-seven patients of group I were primed with slight amount of hMG, the other 34 patients did not use hMG. Ultrasound-guided IMFA was performed 36 hour after human chorionic gonadotropin (hCG) administration. In the next cycle, the basal endocrinology and the basic number of follicles were checked, then IMFA were performed continuously until the basic number of follicles were under 10 per ovary. Afterwards, hMG were used to stimulate ovulation and the pregnant results were followed up. RESULTS: There were 37 cases (88 cycles) of PCOS patients in group I and 34 cases (87 cycles) in group II. After 2 to 3 treatment cycles, the testosterone level became normal in all of patients. The basic follicle number decreased to less than 10 per ovary in 33 cases (89%) in group I and 28 cases (82%) in group II. After hCG stimulation, all of them ovulated. Only 2 patients developed slight ovarian hyperstimulation syndrome (OHSS). Within 3 months after the procedure, 36 patients (51%) became pregnant by controlled ovarian hyperstimulation (COH) protocol after IMFA. CONCLUSIONS: Immature follicle aspiration treatment can improve the abnormal endocrinology, decrease the basic follicle number of the ovary, and achieve pregnancy in following COH cycles, meanwhile, avoid OHSS in PCOS patients.

Adult↗
PubMed2005

[In vitro maturation and fertilization of oocytes from unstimulated cycles in women with infertility due to polycystic ovary syndrome].

OBJECTIVE: To investigate the effect of in vitro maturation (IVM) and fertilization of oocytes from unstimulated cycles in women with infertility due to polycystic ovary syndrome (PCOS). METHODS: Seventy women with PCOS, who came to our clinic during March to were involved in this trial. June 2003. Every cycle was given human chorionic gonadotropin 10,000 IU 36 h before oocyte retrieval. Immature oocytes were matured in vitro and fertilized, and the resulting embryos were replaced back to the uterus. RESULTS: A total of 94 IVM cycles were performed and 1283 oocytes were obtained. The overall maturation, fertilization and cleavage rates were 65.3%, 66.0% and 48.0% respectively. Maturation, fertilization, cleavage and high quality embryo rates had no difference between metaphase I stage oocytes (69.7%, 71.7%, 52.2% and 26.1% respectively) and germinal vesical (GV) stage oocytes (67.7%, 66.4%, 47.6% and 24.1% respectively), but the rates in those oocytes which could not be classified (44.8%, 53.8%, 46.2% and 16.9% respectively) were much lower than the former two groups. After embryo transfer, 18 pregnancies were reported (24%). CONCLUSION: IVM/IVF-ET in unstimulated cycles is a feasible treatment for women with PCOS.

Adult↗
PubMed2005

[Changes of serum soluble P-selectin and tumor necrotic factor-alpha in patients with CMV induced acute coronary syndrome].

OBJECTIVE: To explore the changes and relationship between serum soluble P-selectin, tumor necrosis factor-alpha (TNF-alpha) in coronary heart disease patients with acute coronary syndrome (ACS) and human cytomegalovirus (HCMV) infection. METHODS: The levels of circulating soluble P-selectin, TNF-alpha, HCMV-IgM and HCMV-IgG were determined by enzyme-linked immunosorbent assay (ELISA) in 79 cases for ACS group, 30 cases for stable angina (SA) group and 30 healthy control cases. RESULTS: (1) The serum positive rate of HCMV-IgM and HCMV-IgG in the ACS, SA and healthy control groups were 30.4% (24/79), 10.0% (3/30) and 6.7% (2/30); 86.1% (68/79), 80.0% (24/30) and 53.3% (16/30), respectively. Positive rate of HCMV-IgM in the ACS was higher than those in SA and healthy control groups (P < 0.01), positive rate of HCMV-IgG in the ACS and SA groups were higher than that of the healthy control group (P < 0.01). (2) Compared with the SA group and healthy control group, the levels of the serum soluble P-selectin and TNF-alpha were significantly higher in patients with ACS [(6437.3 +/- 666.9) pg/ml vs. (1520.0 +/- 112.7) pg/ml and (1481.0 +/- 109.1) pg/ml, (56.2 +/- 18.4) pg/ml vs. (27.3 +/- 13.7) pg/ml and (28.1 +/- 11.3) pg/ml], respectively, P < 0.01). The AMI group, compared with the UA group in the ACS group, had significantly higher levels of the serum soluble P-selectin and TNF-alpha (P < 0.01). Compared with the SA group, the levels of the serum soluble P-selectin and TNF-alpha were not significantly different in healthy control group. (3) The levels of the serum soluble P-selectin and TNF-alpha in HCMV-IgM positive patients were significantly higher than the HCMV-IgM negative patients in the ACS group (P < 0.01). CONCLUSION: The chronic infection with HCMV might injure endothelial cells that subsequently contribute to the formation and progression of atherosclerosis, the acute infection with HCMV may induce increased serum levels of soluble P-selectin and TNF-alpha that might participate in acute coronary events.

Acute Coronary Syndrome↗