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Biomedical subjects

S Duan

Publications and source records attributed to S Duan.

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

[The natural history of HIV infection among IDUs in Ruili, Yunnan province, China].

OBJECTIVE: To study the natural history of HIV infections among intravenous drug users. METHODS: Six hundred and twenty five HIV infected people in Ruili, Yunnan province were observed. Retrospective data was analysed combined with a cross - sectional survey. RESULTS: The number of death was 190 among 625 HIV - positive people. The cumulative death rate among HIV infected persons was 76.9 per 1,000 person - year, and the AIDS related death rate was 19.8 per 1,000 person - year. The median survival period of HIV infected persons was 9 years, and the median incubation period was about 8 years. CONCLUSION: Of HIV infected people in Ruili, the median survival and incubation period were shorter compared with those in the United States and Western Europe.

Adult↗
PubMed2000

[Cloning and expression of caiDE genes in E. coli BL21(DE3)].

The caiDE genes for carnitine racemase and its relative factor were cloned into pUC18 from the chromosomal DNA of E. coli MC4100 by shot-gun approach and have been verified by sequence analysis. The target plasmid was named as pJX393 and subcloned to form a transcription plasmid pDSW2. After its transformation into BL21(DE3) strain and induction by IPTG, the recombinant strain containing pDSW2 expressed two apparent protein bands on SDS-PAGE, whose molecular weight were 30 kD and 24 kD individually.

Base Sequence↗
PubMed1999

Glutamate induces rapid upregulation of astrocyte glutamate transport and cell-surface expression of GLAST.

Glutamate transporters clear glutamate from the extracellular space by high-affinity binding and uptake. Factors that regulate glutamate transporter expression and activity can thereby influence excitatory neurotransmission. Transporter function in GABAergic and other systems has been shown to be regulated by transporter substrates. Here, glutamate regulation of glutamate transport was studied using primary murine astrocyte cultures that express the GLAST (EAAT1) and GLT-1 (EAAT2) transporter subtypes. Glutamate was found to stimulate glutamate transport capacity (V(max)) in a dose- and time-dependent manner. The maximal increase was 100%, with an ED(50) of 40 microM glutamate and with onset beginning approximately 15 min after onset of glutamate exposure. The uptake stimulation was reproduced by D-aspartate, which is also a transporter substrate, but not by nontransported glutamate receptor agonists. Moreover, glutamate incubation did not stimulate transport when performed in a sodium-free medium, suggesting that the stimulatory effect of glutamate is triggered by increased transporter activity rather than receptor activation. Treatment with the actin-disrupting agents cytochalasin B or cytochalasin D prevented the glutamate-induced increase in glutamate uptake. Biotinylation labeling of membrane surface proteins showed that glutamate incubation produced an increase in GLAST expression at the astrocyte cell surface. These results suggest that cell-surface expression of GLAST can be rapidly regulated by glutamate through a process triggered by GLAST activity and involving the actin cytoskeleton. This feedback loop provides a mechanism by which changes in extracellular glutamate concentrations could rapidly modulate astrocyte glutamate transport capacity.

ATP-Binding Cassette Transporters↗
PubMed1999

Selective inhibition of transient K+ current by La3+ in crab peptide-secretory neurons.

Although divalent cations and lanthides are well-known inhibitors of voltage-dependent Ca2+ currents (ICa), their ability to selectively inhibit a voltage-gated K+ current is less widely documented. We report that La3+ inhibits the transient K+ current (IA) of crab (Cardisoma carnifex) neurosecretory cells at ED50 approximately 5 microM, similar to that blocking ICa, without effecting the delayed rectifier K+ current (IK). Neurons were dissociated from the major crustacean neuroendocrine system, the X-organ-sinus gland, plated in defined medium, and recorded by whole cell patch clamp after 1-2 days in culture. The bath saline included 0.5 microM TTX and 0.5 mM CdCl2 to eliminate inward currents. Responses to depolarizing steps from a holding potential of -40 mV represented primarily IK. They were unchanged by La3+ up to 500 microM. Currents from -80 mV in the presence of 20 mM TEA were shown to represent primarily IA. La3+ (with TEA) reduced IA and maximum conductance (GA) by approximately 10% for 1 microM and another 10% each in 10 and 100 microM La3+. Normalized GA-V curves were well fit with a single Boltzmann function, with V1/2 +4 mV and slope 15 mV in control; V1/2 was successively approximately 15 mV depolarized and slope increased approximately 2 mV for each of these La3+ concentrations. Cd2+ (1 mM), Zn2+ (200 microM), and Pb2+ (100 microM) or removal of saline Mg2+ (26 mM) had little or no effect on IA. Steady-state inactivation showed similar right shifts (from V1/2 -39 mV) and slope increases (from 2.5 mV) in 10 and 100 microM La3+. Time to peak IA was slowed in 10 and 100 microM La3+, whereas curves of normalized time constants of initial decay from peak IA versus Vc were right-shifted successively approximately 15 mV for the three La3+ concentrations. The observations were fitted by a Woodhull-type model postulating a La3+-selective site that lies 0.26-0.34 of the distance across the membrane electric field, and both block of K+ movement and interaction with voltage-gating mechanisms; block can be relieved by depolarization and/or outward current. The observation of selective inhibition of IA by micromolar La3+ raises concerns about its use in studies of ICa to evaluate contamination by outward current.

Animals↗
PubMed1999

[Molecular characterization of glucose-6-phosphate dehydrogenase variants in four ethnic groups in Yunnan province of China].

OBJECTIVE: In order to understand the molecular evolution, race origin and the relationship between the G6PD gene structure and clinical symptoms, the authors identified the molecular characterization of glucose-6-phosphate dehydrogenase and determined the G6PD gene frequency in four ethnic groups in Yunnan province of China. METHODS: The point mutations of G6PD were detected by Mismatch-PCR/RE, SSCP,ARMS,DNA sequence and so on. G6PD gene frequency was determined by Hardy-Weinberg Law. RESULTS: G6PD G1388A, G1376T,A95G mutations were determined in Bai and Dai people for the first time and G1388A also in Harni people by DNA sequence. G6PD C1024T were detected in Dai population by Mismatch-PCR/RE. The gene frequency of G6PD in Bai population in Dali city is 0.0113, and the incidence is 1.19% which are different from those in Dai population. CONCLUSION: G6PD G1388A,G1376T, A95G and C1024T are the mutations in national minorities as well as in the Han people. The results suggest that different national minorities of China may have the same ancestor. The incidence of G6PD deficiency and the G6PD gene frequency in Bai population are different from those in Dai population. The distribution of G6PD deficiency in Yunnan is associated with the distribution of malaria epidemic in that province.

China↗
PubMed1998

[Solid-phase microextraction of dichlorvos from white spirits].

DDVP was isolated from white spirits using Solid-Phase Microextraction (SPME) technique, and determined by wide-bore capillary gas chromatography (GC) coupling a flame ionization detector. This method had an excellent linearity among 0.5-12 mg/L. Correlation coefficient and minimum detectable concentration were 0.9983 and 0.05 mg/L respectively. This method enables the extraction, the enrichment and the injection to integrate into a single step, and it was free-solvent in whole process. SPME is an advanced technique for the extraction and analysis of the samples.

Alcoholic Beverages↗
PubMed1998

[Chronic pulmonary heart diseases treated by fraxiparin].

OBJECTIVE: The effects of fraxiparine with hypodermic on the treatment of patients with chronic pulmonary heart diseases(CPHD) at acute phase were studied. METHODS: Twenty patients were hypodermically injected with 0.4 ml fraxiparine per day for 7 days as a course. Fibrin fibrinogen degradation products (FDP and D-dimer), antithrombin III (AT-III), PaO2 and PaCO2 were detected before and after the treatment. RESULTS: In the therapy group, FDP and D-dimer decreased after the treatment, AT-III increased. All indexes didn't alter in the control group. CONCLUSION: Fraxiparine is effective on patients with CPHD at acute phase.

Adult↗
PubMed1997

[Simultaneous analysis of theophylline, phenobarbital, amobarbital and carbamazepine in serum by high performance liquid chromatography].

Theophylline, phenobarbital, amobarbital and carbamazepine are the chief therapeutic drugs in clinical practice. Because of the differences among inter-individuals in the metabolic clearance of these drugs and their toxicity at certain levels of concentration in serum, the dosage should be regulated to maintain a therapeutic blood drugs level. To achieve this a rapid and accurate assay method for drugs in blood is necessary. This paper reports that a reversed phase high performance liquid chromatographic (HPLC) method had been established for the simultaneous separation and quantitative determination of the four drugs in serum. The separation was performed on RP-C18 column using methanol:water (1:1) as mobile phase and 4-aminoantipyrime as internal standard. The eluted substances were detected at 210nm.

Amobarbital↗
PubMed1997

Characteristics of risk-taking behaviors, HIV and AIDS knowledge, and risk perception among young males in southwest China.

A cross-sectional survey was undertaken to describe risk-taking behaviors and to assess the knowledge and risk perception of HIV and AIDS among young males aged 18 to 29 years in 82 villages in Longchuan, Yunnan, China, in 1994. Information on demographic, behavioral, and drug-using factors, and knowledge of HIV transmission and prevention, and risk perception was collected using an interviewer-administered anonymous questionnaire. A total of 1,548 individuals were interviewed and 433 drug users, including 52 nonsharing injectors and 140 sharing injectors, were identified. Over half the individuals scored 0 on HIV knowledge, but knowledge was greater among nonsharing drug injectors. Most drug injectors had initiated drug injection after 1990. The reported incidence continues to increase in all three major ethnic groups. Sharing of equipment was common (73%) among injectors. Drug users were four times more likely to have had premarital or extramarital sex, but condoms were used by only 2.5%. Thus, factors promoting spreading of HIV are common in this area. We recommend that a community-based intervention program, targeting both young men and women, be implemented and evaluated in Longchuan as soon as possible.

Acquired Immunodeficiency Syndrome↗
PubMed1997

International clinical trials of HIV vaccines: II. phase I trial of an HIV-1 synthetic peptide vaccine evaluating an accelerated immunization schedule in Yunnan, China.

A Phase 1, double-blind, placebo controlled trial was conducted in Longchuan County, China, to evaluate the safety and immunogenicity of a prototype HIV-1 synthetic peptide vaccine in a target population at risk for HIV infection, and to establish the infrastructure for future large-scale HIV vaccine efficacy trials. Subjects were randomly assigned to receive 100 microg or 500 microg of vaccine or alum placebo, and were given three injections at an accelerated 0, 1, and 2 month schedule. The vaccine was well tolerated with no significant local or systemic reactions observed in any subjects. Fifty-five percent (100 microg dose) and 64% (500 microg dose) of subjects who received the vaccine produced binding antibody to the immunogen as determined by ELISA. However, HIV-1 (MN) neutralizing antibody was detected in only 23% (3/13) of subjects with detectable HIV-1 specific binding antibody. It was concluded that this prototype HIV-1 synthetic peptide vaccine was well tolerated, safe and immunogenic, and that a 0, 1, 2 month schedule was not as effective in stimulating HIV-1 specific neutralizing antibodies compared with previous trials utilizing a 0, 1, 6 month schedule. Finally, this trial demonstrated that well-designed HIV vaccine trials can be performed at this clinical trials site in Yunnan, China, and that this site should be considered for conducting larger safety, immunogenicity and efficacy trials of candidate HIV vaccines.

AIDS Vaccines↗
PubMed1997

A preliminary study on interruption of HBV transmission in uterus.

OBJECTIVE: The infection of Hepatitis B virus (HBV) in the uterus may occur in neonates born to HBV carrier mothers. The rates of intrauterine transmission in these neonates were 10%-16%, Recent studies on the methods of combined passive and active immunizations indicate an efficacy approaching 70%-90%, but intrauterine infection of HBV is the major cause of failure of vaccination to combat hepatitis B in neonates born to HBV carrier mothers. We studied the interruptive effect of HBV specific immunoglobulin (HBIG) before delivery in the prevention of intrauterine transmission of HBV. METHODS: Of 3632 pregnant women, two hundred and four were HBV carriers; they were randomly divided into an HBIG group and a control group. Each subject in the HBIG group received 200 IU of HBIG intramuscularly at 3, 2 and 1 month before delivery. The subjects in the control group did not receive any specific treatment. Blood tests were conducted for all the subjects and their neonates after birth. Blood specimens were tested for HBsAg and HBeAg by enzyme immunoassay (Abbott Kits). RESULTS: The results showed that the rates of intrauterine transmission in the two groups were 5.7% and 14.7% respectively (X2 = 4.58 P < 0.05). No significant differences were observed for the positive rates of HBsAg and HBeAg between the two groups after delivery, but titer of HBsAg was reduced significantly in the HBIG group (t = 4.82, P < 0.01). CONCLUSIONS: Our study suggests that HBV infection in the uterus may be interrupted using multiple HBIG intramuscularly before delivery without any side effects.

Adult↗
PubMed1997

[The peripheral blood levels of TNF alpha and PLA2 activities in dialysis and non-dialysis patients with uremia].

The levels of tumor necrosis factor a (TNF alpha) and phospholipase A2 (PLA2) in peripheral blood were determined by means of the ELISA and improved micromethod in 31 patients with urmia and 12 normal healthy persons. The results showed: 1. In non-dialysis group and during a single dialysis session, a significant increase in the levels of TNF alpha was observed. 2. In non-dialysis and peritoneal dialysis patients, serum levels of PLA2 were significantly increased compared to normal subjects. The results suggest that acute complications induced by hemodialysis are related to increasing levels of TNF alpha, souble PLA2 in cleared by hemodialysis.

Adult↗
PubMed1996

Risk factors for initiation of drug use among young males in southwest China.

To identify risk factors for drug use among young males in southwest China a cross-sectional survey and a non-concurrent cohort study were conducted. Demographic, behavioral and drug-use information was collected from young males aged 18-29 years. The non-concurrent cohort included the period 1 January 1991 to 1 August 1994. A total of 1548 subjects were interviewed. The cumulative incidence increased between 1991 and 1993. Multivariate analysis identified the following significant risk factors for drug use: being divorced/widowed/separated, having been encouraged by friends/others to try drugs, smoking cigarettes, belonging to the Jingpo ethnic group, and having a family member who used drugs in 1991. More than 6 years of education was a protective factor for drug use. Drug use in the community was associated with having been encouraged by friends or others to try drugs (71%), to smoking cigarettes (50%), and to belonging to the Jingpo group (24%). The results are consistent with community based prevention approaches which should be studied carefully because of the unique cultural and epidemiological situation in China.

Adolescent↗
PubMed1996

Risk factors for intravenous drug use and sharing equipment among young male drug users in Longchuan County, south-west China.

OBJECTIVES: To identify the risk factors for intravenous drug use and sharing of equipment in Longchuan County in south-west China. METHODS: Demographic information and sexual and drug-use-related behavior between 1 January 1991 and 1 August 1994 were collected retrospectively from a cohort of young male drug users aged 18-29 years in 82 villages. RESULTS: A total of 433 drug users were identified. The cumulative incidence of intravenous drug use was 40.0% during the 3.7-year study period. The annual incidence increased from 10% in 1991 to over 30% in 1994. Risk factors for intravenous drug use among drug users, according to the multivariate model, included having had premarital/extramarital sex [odds ratio (OR), 1.5; 95% confidence interval (CI), 1.01-2.3], having a family member who used drugs in 1991 (OR, 1.8; 95% CI, 1.1-2.9), and currently not married (OR, 1.6; 95% CI, 0.98-2.7). Being Buddhist protected against intravenous drug use (OR, 0.4; 95% CI, 0.2-0.9). The population attributable fraction was 30% for not being currently married, 17% for having had premarital/extramarital sex and 14% for having a family member who used drugs. The risk factor for sharing of equipment was being of Jingpo ethnicity (OR, 5.8; 95% CI, 2.5-13.8). The average incidence of sharing equipment was 19.6% per year. The population attributable fraction for sharing equipment was 58.5% for being Jingpo. CONCLUSIONS: The incidence of intravenous drug use and sharing equipment is increasing. Therefore, it is urgent that vigorous, effective intervention programs be initiated in southern Yunnan. Unmarried, sexually promiscuous Jingpo drug users with a family history of drug use should be especially targeted. Given the problems of transport and communication in this remote area of China, intervention programs which use existing social, governmental and community networks should be implemented.

Adolescent↗
PubMed1996

Manuduction of adhesive ankylosis of the knee under anesthesia.

This paper reports 60 cases of adhesive ankylosis of the knee treated by manuduction under anesthesia. Excellent and good effects were achieved in 50 cases (83%), and normal function of the knee joint was maintained in 35 of the 40 cases followed up for more than one year.

Adolescent↗
PubMed1996

[A survey on drug abuse in young males in Longchuan County, Yunnan Province].

To understand the prevalence of drug abuse among young people, 1,548 men aged 18 to 29 years were interviewed in 82 natural villages of Longchuan County, Yunnan Province during August to October, 1994, and 433 were found being drug abusers (28%). Most of them started their drug abuse after mid-1980s, and new ones increased yearly. Prevalence of drug abuse in Jingpo ethnic was significantly higher than that in Han and Dai ethnics, and levels of schooling of the people related inversely to their prevalence of drug abuse. Prevalence of drug abuse in young men with smoking, drinking, and premarital or extra-marital sex was much higher than in those without them, and related to their cumulative amounts of smoking and drinking and inversely to their age to start smoking and drinking and to have their first sexual experience. Prevalence of drug abuse in young men who were encouraged to try drugs by others and had family members using drugs was significantly higher than in those without these risk factors. This study suggests drug abuse is prevalent among young men in Longchuan County, and prevention and control of it in adolescents and youngsters should be implemented as soon as possible.

Adolescent↗