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Biomedical subjects

C Tian

Publications and source records attributed to C Tian.

At least 37 records · Page 2Linked to original sources
PubMed1999

Evaluation of novel human immunodeficiency virus type 1 Gag DNA vaccines for protein expression in mammalian cells and induction of immune responses.

Human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes (CTL) are an important parameter of host defenses that limit viral replication after infection. Induction of effective CTL against conserved viral proteins such as Gag may be essential to the development of a safe and effective HIV type 1 (HIV-1) vaccine. DNA vaccination represents a novel strategy for inducing potent CD8(+) CTL responses in vivo. However, expression of HIV-1 structural proteins by DNA vectors has been hampered by a stringent requirement for coexpression with other viral components, such as Rev and RRE. Furthermore, even with Rev and RRE present, the level of expression of HIV-1 Gag, Pol, or Env is very low in murine cells. These problems have limited our ability to address the key issue of how to generate effective CTL responses to Gag in a mouse model. To overcome this problem, we compared several novel DNA expression vectors for HIV-1 Gag protein expression in primate and mouse cells and for generating immune responses in mice after DNA vaccination. A DNA vector containing wild type HIV-1 gag coding sequences did not induce detectable Gag expression in any of the cells tested. Attempts to increase nuclear export of Gag expression RNA by adding the constitutive transport element yielded only a moderate increase in Gag expression in monkey-derived COS cells and an even lower increase in Gag expression in HeLa cells or several mouse cell lines. In contrast, silent-site mutations in the HIV-1 gag coding sequences significantly increased Gag expression levels in all cells tested. Furthermore, this construct induced both Gag-specific antibody and CTL responses in mice after DNA vaccination. Using this construct, we achieved stable expression of HIV-1 Gag in the mouse cell line p815, which can now be used as a target cell for measuring HIV-1 Gag-specific CTL responses in immunized mice. The DNA vectors described in this study should make it possible to systematically evaluate the approaches for maximizing the induction of CTL responses against HIV-1 Gag in mouse and other animal systems.

AIDS Vaccines↗
PubMed1999

Matrix metalloproteinase-2 in a murine model of infantile-type polycystic kidney disease.

It was previously found that elevated levels of matrix metalloproteinase (MMP)-2 (gelatinase A) and -9 (gelatinase B) were synthesized and secreted into the medium by cultured kidney tubules derived from cystic C57BL/6J-cpk mice. To determine whether increased synthesis and secretion occur in vivo in this mouse model of polycystic kidney disease, kidney protein extracts, mRNA, and tissue sections were compared for expression and activity of MMP-2 and -9. Although both MMP were detected in tissue extracts, the differences in expression levels and activity in normal and cystic kidneys were far greater for MMP-2. High levels of MMP-2 seemed to result from increased expression by the cystic kidneys predominantly in the second and third postnatal weeks (a time when the kidneys are undergoing rapid cystic enlargement). Much of the increased MMP was present in the inactive zymogen form, although active enzyme was readily detected by sodium dodecyl sulfate-polyacrylamide gel zymography and in situ zymography. MMP-2 was abnormally localized to the interstitium and to foci between cysts, suggesting that MMP-2 may regulate collagen accumulation at those sites, thus allowing cyst enlargement and limiting the severity of interstitial fibrosis.

Animals↗
PubMed1999

[Cloning of human G-CSF genomic gene and its expression in transgenic mice mammary gland].

Human genomic DNA was used as template of PCR. 1.5 kb G-CSF genomic DNA was obtained using PCR amplification method. Sequence analysis showed that genomic DNA sequence of human G-CSF was correct. The vector of mammary gland expression was constructed and contained whey acid protein (WAP) 5' control region directed human G-CSF genomic DNA. In order to produce transgenic mice, 1200 fertilized eggs were microninjected using WAP-G-CSF fragment. Two male transgenic mice were obtained and identified using PCR method and Southern analysis. Integration rate of human G-CSF gene was 2.37% in mice. Foreign gene could also be identified in F1 and F2 transgenic mice. Expression levels of human G-CSF in transgenic mouse milk were 120-250 ng/ml.

Animals↗
PubMed1999

[On the mechanisms of cardiac hypertrophy].

Here we reviewed the progress of researches on the mechanism of cardiac hypertrophy and discussed its putative mechanisms. With regard to the heredity and variability of familial hypertrophic cardiomyopathy and mitochondrial cardiomyopathy and other changes, we emphasize that the imbalance between the energy supply and demand of the overloaded pressure determines the occurrence of cardiac hypertrophy. Also we refer to the involving roles of the mechanical stress and some paracrine/autocrine factors in cardiac hypertrophy. Finally we hypothesize that there exists an unknown small molecule being involved in regulating the gene expression and phenotype in cardiac hypertrophy.

Animals↗
PubMed1999

[Hybridization experiments using Anopheles minimus from Hainan and Yunnan].

AIM: To observe whether there were any intra-species differences between Anopheles minimus from Hainan(H) and Yunnan(Y). METHODS: Anopheles minimus were collected from cattle shed on the spot. Each isofemale line was set up in the laboratory. Hybridization experiments were conducted by using forced mating between Anopheles minimus from Hainan and Yunnan, for observing the reproductive ability of F1 hybrids. Ovarian nurse cell polytene chromosomes of F1 hybrid females were examined, to observe any synapsis in different zones of chromosomes. RESULTS: No embryo formation was found within the eggs produced by group Y female x H male, the hatching rate was zero. Low hatching rate was shown in other groups with (H female x Y male) F1, except for groups with (H x Y) F1 x Y. Ovarian nurse cell polytene chromosomes from (H x Y) F1 hybrid females showed constant asynapsis at the 29th, 36th and 37th zones in the chromosome 3R, and at the 4th and 6th zones in the chromosome X. CONCLUSION: Reproductive isolation did appear in An. minimus from Hainan and Yunnan.

Animals↗
PubMed1998

SIV-associated nephropathy in rhesus macaques infected with lymphocyte-tropic SIVmac239.

We examined the renal pathology and viral genetic changes following inoculation of six rhesus macaques with lymphocyte-tropic SIVmac239. Portions of the renal cortex were sieved into glomerular and tubulointerstitial (TI) fractions and examined for SIVmac sequences by PCR and for p27 core antigen. SIVmac sequences were detected in renal tissue from five of six macaques (three of five glomerular and five of five TI fractions were positive for SIV by PCR). Glomerulosclerosis (segmental and global) was evident in two macaques that were positive for env sequences in the glomerular fractions. Diffuse mesangial hyperplasia and matrix expansion were present in all three animals with glomerular SIV, as was an increase in glomerular collagen I and collagen IV. Tubulointerstitial inflammation was evident in all virus-inoculated macaques. The TI infiltration of CD68+ cells was most pronounced in the animals with SIVmac present in the glomerulus. All SIVmac-infected macaques exhibited increased glomerular deposition of IgM and to a lesser extent IgG, but no C3 or IgA was evident. Sequence analyses of the viral env gene (gp120) isolated from the glomerular and TI fractions of a macaque that developed glomerulopathy revealed the presence of specific viral variants in glomerular and TI fractions. In addition, chimeric viruses constructed with glomerular but not tubulointerstitial gp120 sequences were converted to a macrophage-tropic phenotype. These results indicate that infection by lymphocyte-tropic SIVmac239 is primarily associated with immunoglobulin deposition in the glomerulus and suggests that when glomerulosclerosis develops there is selection of viral variants that are macrophage tropic in nature.

Animals↗
PubMed1998

Rhesus macaques infected with macrophage-tropic simian immunodeficiency virus (SIVmacR71/17E) exhibit extensive focal segmental and global glomerulosclerosis.

We previously showed that inoculation of rhesus macaques with molecularly cloned lymphocytetropic simian immunodeficiency virus (SIVmac239) results in SIV-associated nephropathy (SIVAN) and that the glomerulosclerotic lesions were associated with the selection of macrophagetropic (M-tropic) variants (V. H. Gattone et al., AIDS Res. Hum. Retroviruses 14:1163-1180, 1998). In the present study, seven rhesus macaques were inoculated with M-tropic SIVmacR71/17E, and the renal pathology was examined at necropsy. All SIVmacR71/17E-infected macaques developed AIDS, and most developed other systemic complications, including SIV-induced encephalitis and lentivirus interstitial pneumonia. There was no correlation between the length of infection (42 to 97 days), circulating CD4(+) T-cell counts, and renal disease. Of the seven macaques inoculated with SIVmacR71/17E, five developed significant mesangial hyperplasia and expansion of matrix and four were clearly azotemic (serum urea nitrogen concentration of 40 to 112 mg/dl). These same five macaques developed focal segmental to global glomerulosclerotic lesions. Increased numbers of glomerular CD68(+) cells (monocytes/macrophages) were found in glomeruli but not the tubulointerstitium of the macaques inoculated with SIVmacR71/17E. All macaques had glomerular deposits of immunoglobulin G (IgG), IgM, and tubuloreticular inclusions, and six of seven had IgA deposition. However, there was no correlation between the presence of circulating anti-SIVmac antibodies, immunoglobulin deposition, and glomerular disease. Tubulointerstitial infiltrates were mild, with little or no correlation to azotemia, while microcystic tubules were evident in those with glomerulosclerosis or azotemia. The four most severely affected macaques were positive for diffuse glomerular immunostaining for viral core p27 antigen, and there was intense staining in the glomeruli of the two macaques with the most severe glomerulosclerosis. Viral sequences were isolated from glomerular and tubulointerstitial fractions from macaques with severe glomerulosclerosis but only from the tubulointerstitial compartment of those that did not develop glomerulosclerosis. Interviral recombinant viruses generated with env sequences isolated from glomeruli confirmed the M-tropic nature of the virus found in the glomeruli. The correlation between the increased number of CD68(+) cells (monocytes/macrophages) in the glomeruli, the localization of p27 antigen in the glomeruli, and the glomerular pathology confirms and extends our previous observations of an association between glomerular infection and infiltration by M-tropic virus and SIVAN.

AIDS-Associated Nephropathy↗
PubMed1998

[Studies of foreign gene integeation during embryo early development].

There are still some problems in transgenic animals. Gene transfer, for example, reamins a difficult and costly task for animals, the vectors carrying the gene coding for the proteins of interest are of unpredictable efficiency. Therefore, it is important to identify foreign gene integration in genomose before transferring fertilized eggs to receptors, in order to increase efficiency of producing transgenic animal. In this paper, the construct that mice whey acid protein (WAP) gene promoter directs G-CSF gene was used to microinject fertilized eggs of mice. Fertilized eggs containing foreign gene were measured by using PCR method. The results showed that 100%, 77.7% and 44.4% retentions of foreign gene were achieved in 1, 2 and 8 cell-stage, respectively. Two part homologous recombination fragments were constructed and coinjected in to fertilized eggs of mice. PCR amplification fragment went beyond this homologous recombination area. If foreign gene could not integrate in to genomose, the fragment of PCR amplification could not be produced during embryo development. The results showed that the rationes of foreign gene integrated in to genomoes in 1, 2 and 8 cell-stage were 11.1%, 55.5% and 44.4%, respectively. This method might provide us a way to screen transgenic eggs when we use embryo section technique in farm animal.

Animals↗
PubMed1997

[A prospective study on transfusion-related hepatitis C virus infection].

64 cases of blood recipients were followed-up for 6 months to study infection of hepatitis C virus. The infection rate of hepatitis C virus was 18.75% in total, including 8 cases of post-transfusion hepatitis C (PT-HC), 1 case of subclinical PT-HC, and 3 cases of anti-HCV sero conversion only. The time of initial ALT abnormality and anti-HCV sero conversion were 28 to 91 (51.9 +/- 20.9) days and 23 to 76 (42.4 +/- 15.9) days after blood transfusion respectively. There were 2 cases with cytomeglovirus infection and another 5 cases with unknown infectious agent were found in this study.

Enzyme-Linked Immunosorbent Assay↗
PubMed1996

[24 patients with aneurysm of membranous ventricular septumi: clinical analysis].

24 patients with aneurysm of the membranous ventricular septum were confirmed by operatively in our hospital. Four patients had true aneurysm of the membranous ventricular septum, and 20 false. According to the difference of membranous aneurysm (true or false) and the size of the defect, different methods of the operation were adopted. Postoperation intracardiac residual shunt was avoided. There was no death in the group. Follow-up for 9 years to 6 months showed excellent long-term results. The authors consider that the diagnosis of this disease before operation is difficult.

Adolescent↗
PubMed1995

HIV risk behaviors but absence of infection among drug users in detoxification centers outside Yunnan province, China, 1993.

OBJECTIVES: To date, HIV spread in China has occurred principally among injecting drug users (IDU) in remote border regions of Yunnan province. We therefore sought to better understand the risks for and prevalence of HIV infection among drug users in parts of China outside Yunnan province. METHODS: A behavioral survey of drug use and AIDS-related knowledge was conducted among all consenting drug users who entered treatment from 1 November to 31 December 1993 in seven provincial drug detoxification centers outside Yunnan province. After giving verbal informed consent, all drug users were tested for HIV. RESULTS: Of the 1293 study participants, 207 (16%) reported injecting drugs. The proportion of IDU among all drug users varied widely by region, from 1% in Sha'anxi and Gansu provinces in the northwest region to 58% in Guangxi province in the south. IDU were more likely than non-IDU to be single and unemployed or self-employed, but did not differ in other demographic aspects. Among all drug users, 2% reported sharing needles without cleaning equipment, while 5% shared with some cleaning. Although 1060 (82%) drug users had heard of AIDS and most knew about its sexual (79%), parenteral (77%), and perinatal (60%) modes of transmission, many had misconceptions about its spread by casual contact. Of the 207 IDU tested for HIV, none were HIV-positive (95% confidence interval, 0--1.4). CONCLUSION: The absence of HIV infections detected in this study suggests that the prevalence of HIV is currently low among IDU in China outside the Yunnan province. However, the behavior of these IDU puts them at high risk for HIV infection. Prevention efforts are needed to prevent the spread of HIV among IDU throughout China and to avoid the experience of neighboring countries in Asia.

Adolescent↗
PubMed1995

[Biomechanics of bone in experimental diabetic rats].

The biomechanics of bone in diabetics and its response to insulin treatment was not clear. We investigated the impact of alloxan-induced diabetes and insulin treatment on the biomechanical characteristics of bones. Sprague-Dawley rats were divided into three groups: normal control (NC), diabetics (DM), and diabetics treated with insulin (DI). After 3 months the rats were killed. The load at bending test of the femurs was significantly decreased in DM compared to NC and DI. There was no statistical difference between DI and NC. Structurally, DM was significantly lower than NC and DI in the stress at the proportional limit and the maximum load of vertebrae. In material properties, marked deteriorations in the vertebrae were observed in DM and DI. The plasticity of the vertebrae observed in NC disappeared in DM, in which fragility was obvious. DI was not different from DM. We found that the structure and the material property of the bones deteriorate significantly in diabetes induced by alloxan. Insulin treatment inhibits most of biomechanical changes in bone induced by experimental diabetes, but not all of them. The data suggests that the relations between insulin and the material properties of diabetic bones remain to be studied.

Animals↗
PubMed1995

[High efficiency expression of IL-4 using modified cDNA expression vector in mammalian cells].

In order to express eukaryotic gene in eukaryotic cells, a cDNA library was constructed and screened with synthesized probe of IL-4 cDNA. The obtained cDNA fragment 739 bp in length was inserted into pi H3M plasmid and expressed (8 x 10(3) IU/ml) in COS cells. A pdB-HhIL-4 expression plasmid was constructed using pdKCR and pdBPV-1 plasmid and transfected into mouse C127 cells by calcium phosphate coprecipitation. Transfected cells exhibited altered cell morphology, could be continuously cultured in DMEM essential medium and secreted IL-4 lymphokine into 1% FCS condition culture medium. High biological activity (2 x 10(4)/ml) from the culture supernatant was obtained by FACS analysis of Fc epsilon receptor expression on B cell surface.

Animals↗
PubMed1994

Fabrication and characterization of glucose sensors based on a microarray H2O2 electrode.

A glucose sensor was recently developed by modifying an immobilized GOD (glucose oxidase) membrane and coating Nafion diffusion limiting membrane over an amperometric H2O2 MAE (microarray electrode), which was fabricated by using standard planar processing. The chip of the sensor is 2.5 mm by 15. The MAE is composed of an Ag/AgCl RE (reference electrode), a Pt CE (counter electrode) and two sets of Pt WE (working electrode), each set consists of five bands. Silicon nitride was chosen as the top insulator. Six MAEs different in both width and length of the band were examined and the MAE with the narrowest width (10 microns) of bands exhibits the best electrochemical performances. The glucose sensor based on the MAE B1-2 presents a linear range of 0.5-40 mM glucose at 37 degrees C with a 1/15 M phosphate buffer solution (pH = 7.0) as supporting electrolyte. The sensitivity, background current, response time, CV (coefficient of variation) and long-term stability of the sensor are 7.1 +/- 0.5 nA/mM, 2 +/- 0.5 nA, 30 s, 3.4% and 6 days respectively.

Biosensing Techniques↗
PubMed1994

Injecting drug use and HIV infection in southwest China.

OBJECTIVES: To determine the prevalence of drug injection among drug users, the seroprevalence of HIV and risk factors for HIV infection among injecting drug users (IDU), and to determine heterosexual transmission of HIV among IDU and their spouses in southwest China. METHODS: Using a cross-sectional design, we conducted an HIV seroprevalence and behavioral survey in three rural counties of Yunnan province, Ruili, Longchuan and Luxi in southwest China, bordering Myanmar (Burma). A total of 860 drug users were recruited in randomly selected communities at the three study sites (response rate, 97%). In addition, a random sample of 62 wives of HIV-infected IDU were assembled from 460 known HIV-positive IDU in Ruili and Longchuan (response rate, 81%). RESULTS: In the sample of 860 drug users, 33% reported injecting drugs. Among the 282 subjects who injected drugs, 82% began intravenous drug use after 1988; 64% injected drugs at least once every day. All subjects shared needles but none cleaned the injection equipment with alcohol or bleach. Overall, 49% tested HIV-positive. HIV seropositivity was independently correlated with a longer history of drug injecting, daily injecting, frequent needle-sharing, being younger, and living in Ruili county. Among the 62 wives of HIV-positive IDU, none used condoms during sex and 10% tested HIV-positive. CONCLUSIONS: We conclude that the introduction of HIV into drug-using communities and the rapid increase in heroin injecting in this population appear to have triggered an explosive HIV epidemic among IDU in southwest China. We recommend that AIDS prevention efforts should begin immediately and focus on discouraging the shift from opium smoking to heroin injecting, needle-sharing, and unprotected sex among drug users and their partners.

Adult↗
PubMed1994

Tuberculosis in human immunodeficiency virus-exposed or -infected United States children.

This study was designed to provide a preliminary assessment of the occurrence of tuberculosis exposure, infection and disease within a national sample of infants and children with human immunodeficiency virus (HIV) exposure or infection, and to determine the prevalence of Mycobacterium tuberculosis isolates resistant both to isoniazid and rifampin in these patients or their adult source contacts. A retrospective questionnaire survey was conducted of infants and children with HIV exposure or infection evaluated by pediatric HIV referral centers in the United States comprising the pediatric units or subunits of the Pediatric Acquired Immunodeficiency Syndrome Clinical Trials Group (PACTG). Seventy of 72 sites during a mean period of 5 (range, 1 to 12) years participated in this study and had provided care for 14,038 patients. There were 75 cumulative total cases of tuberculosis disease seen since each site was established. Therapy for asymptomatic infection was given to another 40 children and for tuberculosis exposure to 71 children. Annualized case rates were 478/100,000 for sites established in 1990 to 1992, 117/100,000 for 1988 to 1989, 63/100,000 for 1986 to 1987 and 58/100,000 for 1981 to 1985 (P = 0.05, Spearman's p test for trend). By comparison, the 1992 age-specific tuberculosis case rate for all U.S. children < 5 years was 5.5/100,000. Twenty percent of isolates from PACTG patients and 15% of isolates from adult source contacts were resistant to isoniazid and rifampin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗