Biomedical subjects
Publications and source records attributed to Lei Han.
A unique noninterpenetrated 2D bilayer cobalt(II)-organic framework, [[Co(dpe)(NO(2)-BDC)].0.5(dpe)](n).nH(2)O (1), possessing nanoscale rectangular channels that clathrate large organic molecules, has been hydrothermally synthesized by reaction of cobalt(II) salt with 5-nitro-1,3-benzenedicarboxylic acid (NO(2)-H(2)BDC) and 1,2-bis(4-pyridyl)ethylene (dpe).
China is currently undergoing a serious HIV-1 epidemic in intravenous drug users, sex workers, and former plasma donors. Little is known, however, about HIV-1 risk in Chinese men who have sex with men. In this study of seroprevalence in such men in Beijing, we recorded 15 (3.1%, 95% CI 1.8-5.1) of 481 men infected with HIV-1. Overall, 238 (49%) of participants reported unprotected anal intercourse during the previous 6 months. HIV-1 seropositivity was independently associated with being older than 39 years and having had more than 20 male sexual partners. Most men older than 39 years had been married. Our findings suggest the potential for spread of HIV-1 between men who have sex with men and to their heterosexual partners.
Pathological fibroproliferation after tissue injury is harmful and may lead to organ dysfunction. Unfortunately, fibroproliferative diseases remain intractable to current therapeutic strategies. Thus, new therapeutic approaches are needed. One possible approach is to promote resolution of physiological fibroproliferation that follows injury before it becomes pathological by activating apoptosis selectively in fibrotic lesions. However, it is not known whether selective elimination of fibroblasts will prevent fibrosis or impede repair or worsen injury by eliminating topographic signals essential to organ reconstitution. To address this question, a tractable in vivo model system is needed in which fibroblasts can be targeted to undergo apoptosis at a chosen time and place. We developed transgenic mice expressing HSV-TK from the type I collagen promoter to determine whether selective elimination of fibroblasts actively forming fibrotic lesions is an effective therapeutic strategy for fibroproliferative disorders. The transgene renders fibroblasts actively forming fibrotic tissue susceptible to ganciclovir. To validate the transgenic model we examined whether administration of ganciclovir prevents the development of fibrosis in sponges implanted subcutaneously in the backs of the transgenic mice. We demonstrate that fibroblasts/myofibroblasts isolated from sponges express HSV-TK protein and are selectively ablated by ganciclovir in vitro. In adult transgenic mice, ganciclovir treatment attenuated the development of fibrotic tissue in the sponges both biochemically and histologically. We conclude that this transgenic model system is an ideal approach to determine whether targeted ablation of fibroblasts is an effective therapeutic strategy for fibrotic diseases.
We treated a male patient with Crimean-Congo hemorrhagic fever (CCHF). The diagnosis of CCHF was confirmed by reverse transcription-PCR and recombinant nucleoprotein (rNP)-based immunoglobulin G (IgG) and IgM capture enzyme-linked immunosorbent assays of serially collected serum samples. The patient was treated with intravenous ribavirin and recovered with no consequences. The study indicates that rNP-based CCHF virus antibody detection systems are useful for confirming CCHF virus infections. This case also suggests that intravenous ribavirin therapy may be promising for the treatment of CCHF patients.
Recent studies of U.S. men who have sex with men (MSM) have reported high rates of unprotected anal intercourse but low rates of HIV infection among Asian and Pacific Islander (API) men. We investigated this discrepancy by examining the characteristics of sexual partnerships among API MSM. Multivariate logistic regression analyses found that having an API partner was related to having unprotected anal intercourse after controlling for respondent's age, number of sexual partners, and partner type. Having an API partner and a younger partner were related to respondent reports of unprotected insertive anal intercourse. However, a partner's race and age did not predict unprotected receptive anal intercourse. Study findings suggest that HIV prevalence among API MSM may have remained relatively low because higher risk sexual practices occur more frequently within a lower risk API group compared with higher risk non-API groups. However, because the possibility for the rise of HV infection in this population still exists if HIV spreads from older to younger men, HIV prevention efforts must target partner characteristics to maintain low HIV prevalence among API MSM.
OBJECTIVE: To investigate the impact of rheumatoid arthritis (RA)-associated HLA-DRbeta1 * 0401, * 0402, * 0403, * 0404 and * 0101 subtypes on the protein kinase A (PKA) signaling pathway. METHODS: Adenylate cyclase (AC), cAMP and PKA activity in transfectants expressing RA-associated HLA-DRbeta1 subtypes and their mutants were detected. RESULTS: Compared to HLA-DRbeta1 * 0402 transfectants, the RA-associated HLA-DRbeta1 * 0401, * 0404 and * 0101 transfectants produced significantly lower levels of AC, cAMP and PKA. CONCLUSION: RA-associated HLA-DRbeta1 molecules are involved in the pathogenesis of RA through down-regulation of the PKA signaling pathway.
OBJECTIVE: The recombinant adenovirus vector carrying antisense multidrug resistance-associated protein (MRP) was constructed for use in gene therapy to overcome drug resistance in hepatocellular carcinoma. METHODS: The fragment of MRP gene encoding 5' region was cloned reversely into the shuttle plasmid pAdTrack-CMV, with the resultant plasmid and the backbone plasmid pAdEasy-1, the homologous recombination took place in the E. coli BJ5183 and the recombinant adenoviral plasmid was generated. The adenoviruses were packaged and amplified in the 293 cells. Then the viral titer was checked by GFP. RESULTS: The recombinant adenovirus vector carrying antisense MRP was constructed successfully. The viral titer was 2.5 x 10(9). CONCLUSION: The recombinant adenovirus vector constructed by us could introduce the antisense MRP into the human drug-resistant hepatocellular cell line effectively, which would provide experimental basis for the mechanisms and reversal methods of the multidrug resistance in human hepatocellular carcinoma.
OBJECTIVE: To investigate the situation of Xinjiang hemorrhagic fever (XHF) in patients who have been diagnosed as XHF by clinical methods and to predict the condition in people who were liable to infection and in the host-animals. METHODS: Sera collected from XHF patients and some peasants under the risk of contracting the disease, followed by checking the specific antibody against XHF with IgG-ELISA and IgM capture ELISA, and XHF viral antigen with antigen capture ELISA. In addition, 80 sheep/goats serums were collected from two places where there were more XHF cases and specific IgG antibody against XHF checked by ELISA method. RESULTS: Positive rate of IgG and IgM antibodies were 39.62% (21/53) and 20.75% (11/53) respectively in the serums of patients; one patient's serum showed XHFV antigen positive by antigen capture ELISA. IgG antibody positive rate for peasants' sera was 21.05% (4/19), but IgM antibody detection showed negative for all sera. In sera from 80 sheep and goats, 70% (56/80) showed IgG positive. CONCLUSION: Results showed that XHF broke out in Bachu county from April to June 2001 while recessive infection of the disease remained serious.
OBJECTIVE: To explore the relationship between the structure and function at molecular level and the routes of transmission of Xinjiang hemorrhagic fever (XHF) virus. METHODS: S genes of five XHF virus strains were cloned, sequenced and compared with that of other Crimean-Congo hemorrhagic fever virus strains. RESULTS: It was found that S genes of the five viruses had 1,672 nuclei tides, while ORF of them including 1,449 nuclei tides and coded with a protein of 482 amino acid. The nucleotides homology of Chinese isolates (93.0%-99.5%) was obviously higher than that of any other S genes strains identified in other countries'. Phylogenetic tree showed that all Chinese isolates clustered into one branch and could be further divided into another three groups. CONCLUSION: The sequential difference of S genes was not totally related to the host, areas and time of the viruses isolated.
DNA from a region downstream of and overlapping the polyketide synthase (PKS) gene cluster for jadomycin B biosynthesis in Streptomyces venezuelae was cloned and sequenced. Analysis of the nucleotide sequence located one complete ORF (ORF6), an incomplete one representing the 3' region of ORF4 in the PKS cluster, and a second incomplete one (ORF7). The deduced amino acid sequences for ORFs 6 and 7 resemble those of oxygenases. Since a plausible biosynthetic pathway for jadomycin B includes an angular polyketide intermediate that undergoes oxidative ring fission before condensation with an amino acid, we subcloned one of the presumptive oxygenase genes (ORF6) in a segregationally unstable shuttle vector (pHJL400) and disrupted it by inserting the gene for apramycin resistance. Transformation of S. venezuelae with the disruption vector and selection for apramycin resistance gave mutants blocked in jadomycin biosynthesis. Southern hybridization confirmed that gene replacement had occurred. Cultures of the mutants accumulated a metabolite identified by comparison with an authentic sample as rabelomycin, a non-nitrogenous polyketide-derived antibiotic originally isolated from Streptomyces olivaceus.