Biomedical subjects

H Xing

Publications and source records attributed to H Xing.

At least 19 recordsLinked to original sources

PubMed2006

Menstrual cycle lengths and bone mineral density: a cross-sectional, population-based study in rural Chinese women ages 30-49 years.

INTRODUCTION: The menstrual cycle involves periodic fluctuations in estrogen and progesterone levels. Longer cycles have been associated with longer follicular phase, delayed estrogen peak and a lower mean oestradiol level of the entire cycle. METHODS: We hypothesized that prolonged menstrual cycle length is associated with decreased bone mineral density (BMD) in a population of pre- and perimenopausal women. This population-based cross-sectional study was conducted in rural Anhui province, China. It includes 4,771 women, aged 30 to 49 years, who did not smoke or drink alcohol, and did not use oral contraceptives or breastfeed during the previous year. Dual-energy X-ray absorptionometry (DEXA) BMD measurements were taken at four skeletal sites: whole body, total hip, femoral neck and lumbar spine. Menstrual cycle characteristics (polymenorrhea, short normal, long normal, oligomenorrhea, 90-day amenorrhea, irregular cycle) in the prior year were assessed by questionnaire. RESULTS: Prolonged menstrual cycle was consistently associated with decreased BMD at whole body, total hip, and femoral neck in both age 30-39, and age 40-49 stratum (p(trend)<0.05). Prolonged menstrual cycle was also associated with decreased lumbar spine BMD for women aged 40-49 (p(trend)<0.05). Among women with normal cycles aged 30-39, menstrual cycle length in the previous year was inversely associated with whole-body BMD (p<0.05). Women with 90-day amenorrhea had significantly lower mean total hip and femoral neck BMD relative to women with short normal cycles in the 30-39 age group; and had significantly lower whole body and total hip BMD relative to short normal cycles in the 40-49 age group. BMD in polymenorrheic women did not differ from BMD in women with short normal cycles at any of the skeletal sites. CONCLUSIONS: We conclude that prolonged menstrual cycle length is associated with decreased BMD in pre- and perimenopausal women in this population.

Adult↗

PubMed2006

Inhibition of ovarian cancer metastasis by adeno-associated virus-mediated gene transfer of nm23H1 in an orthotopic implantation model.

Ovarian cancer is one of the most threatening malignant tumors in females due to the frequent occurrence of metastasis that precedes diagnosis. The present study explored the possibility of preventing ovarian cancer metastasis by promoting nm23H1 expression through adeno-associated virus (AAV)-mediated gene transfer. A cell line of high metastatic potential, SW626-M4, was derived by in vivo selection and used to establish an ovarian cancer metastasis model in the mouse. Liver metastasis and animal survival time were measured after transfer of a recombinant adeno-associated viral vector expressing nm23H1 (AAV-nm23H1) into the aforementioned model. Intraperitoneal injection of AAV-nm23H1 into this orthotopic implantation model of ovarian cancer resulted in (1) expression of the exogenous gene in more than 95% of tumor cells in situ in nude mice; (2) a 60% reduction in the number of animals developing liver metastases; and (3) a 35-day prolongation of median survival time compared with the untreated host group. In conclusion, the results support the feasibility of induction of nm23H1 expression through gene transfer as a therapeutic strategy for preventing metastases and prolonging host survival time, and indicate that AAV vectors deserve attention in the design of future gene therapy approaches to achieving long-term expression of curative genes in vivo.

Adenocarcinoma↗

PubMed2006

[Subtype and sequence analysis of the ENV gene of HIV-1 drug users in Guangdong Pearl River delta.].

BACKGROUND: To determine the subtype of HIV-1 of drug users (DUS) in Guangdong Pearl River delta. METHODS: HIV-1 pro-viral DNA from buffy coat of 43 DUS in Guangdong was amplified by nested PCR. The C2-V3 regions of HIV-1 ENV gene was sequenced directly from the PCR product and analyzed. RESULTS: The 43 DUS were confirmed to be infected with four HIV-1 subtype or Circulating Recombinant Form (CRFs): 07-BC(n=29), AE(n=9), 08-BC(n=3) and B(n=2). Genetic distances showed that the AE group was the closest to CM240 strain isolated in Thailand which is mainly circulating in sexually transmitted infector. The 07-BC group was the closest to C54A strain isolated in Northeastern China. The 08-BC group was the closest to 97CNGX-9F strain isolated in Guangxi, China. The B strain was the closest to rl42 strain isolated in Thailand. CONCLUSION: HIV-1 CRFs 07-BC predominates in DUS in Guangdong Pearl River delta.

Base Sequence↗

PubMed2006

[Development of a rapid subtype-screening assay for the env region of HIV-1 CRF strains in Guangxi.].

BACKGROUND: To develop a simple and rapid subtype-screening assay for the env region of the circulating recombinant form (CRF) of human immunodeficiency virus type 1 (HIV-1) in Guangxi. METHODS: Proviral DNA from HIV-1 positive samples were extracted and subjected to the first round PCR with universal primers for the env region that can detect HIV-1 M group isolates. In the second round PCR, two pairs of subtype-specific primers that were designed to detect subtype C or B'/C and CRF01-AE respectively were added into one tube. The PCR products of different subtypes could be distinguished in agarose-gel electrophoresis. Additionally, all of these samples were sequenced and analyzed phylogenetically. RESULTS: Phylogenetic analysis of the env region of 50 samples showed that 3 samples (6%) were infected with CRF08-BC, 43 (86%) with CRF01-AE, and 4 (8%) remained unclassifiable. Detection of the subtype-specific primer sets revealed that 3 were subtype C or B'/C (100%), 39 were CRF01-AE (90.7%), with an adequate sensitivity (91.3%) and a high specificity (100%). Non-specific bands occasionally appeared but did not interfere with interpretation of the results. The phylogenetic analysis was consistent with subtype-specific primer sets and the consistency rate was 92%. The average reproducibility was 100% for CRF08-BC samples and 93.8% for CRF01-AE samples. CONCLUSION: A simple, rapid and low cost assay was developed for subtype-screening of CRF01-AE in Guangxi.

China↗

PubMed2005

Post-ischemic delivery of the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor rosuvastatin protects against focal cerebral ischemia in mice via inhibition of extracellular-regulated kinase-1/-2.

After recent clinical trials, statins have gained increasing significance in secondary stroke prevention. From experimental studies, it is well established that statins have beneficial action when delivered prophylactically prior to a stroke. Conversely, much less is known about the effects of statins on injury development when delivered after ischemia. We here examined the effects of a post-ischemic delivery of rosuvastatin (0.5, 5 or 20 mg/kg, administered i.p. immediately after reperfusion onset), a potent 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on brain injury and cell signaling after focal cerebral ischemia, induced by 90 min of intraluminal middle cerebral artery occlusion in mice. In animals receiving normal saline, 0.5 or 5 mg/kg rosuvastatin, middle cerebral artery occlusions resulted in reproducible brain infarcts at 24 h after reperfusion onset, which did not differ in size. However, rosuvastatin, administered at higher doses (20 mg/kg), reduced infarct volume at 24 and 48 h after ischemia (by 34+/-16% and 18+/-3%, respectively, P<0.05). Western blots revealed that rosuvastatin decreased phosphorylated extracellular-regulated kinase-1/-2 and reduced activated caspase-3 levels in ischemic brain areas, while endothelial NO synthase expression, p38 and Jun kinase phosphorylation were not influenced by the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor. Rosuvastatin also significantly diminished expression levels of inducible NO synthase in the ischemic brain. Our results indicate that rosuvastatin may have utility not only as stroke prophylaxis but also as acute therapy inhibiting executive cell death pathways.

Animals↗

PubMed2004

The lack of epidemiological link between the HIV type 1 infections in Hong Kong and Mainland China.

Blood samples were collected from 139 newly reported HIV-1 infections in Hong Kong over a 3-year period between 1999 and 2001, representing 22.8% of all reported cases. A majority of the patients were male (85.6%), Chinese (74%), and adult (97.1%) and acquired HIV-1 through sexual transmission (88.2%). The B and CRF01_AE were the major subtypes detected--49.6% and 44.6%, respectively. Over time, the frequency of CRF01_AE subtype increased, the B subtype decreased, and new subtypes of C (4) 2.8%, B' (1) 0.7%, and CRF07_BC (3) 2.2% emerged. The CRF01_AE subtype was commoner in female, Chinese, heterosexuals, and injection drug users whereas B subtype was commoner in male, white, and people with homosexual/bisexual contacts. There was no common source of infection from the analysis except a discernible cluster of Vietnamese injection drug users with the CRF01_AE subtype. The molecular findings did not suggest an epidemiological link between HIV infection in Hong Kong and Mainland China. Hong Kong's longstanding and extensive methadone treatment network may have contributed to the phenomenon.

Adult↗

PubMed2001

Exposure to ethanol and nicotine during the brain growth spurt: spatial DMP performance in male rats.

Male Long-Evans rats were reared artificially and, using a 2x2 design, were exposed from postnatal days (PD) 6-9 to ethanol (ET: 6.5 g kg(-1) day(-1) "binge" exposure) and/or nicotine bitartrate (NIC: 6 mg kg(-1) day(-1) continuous exposure) via gastrostomy tubes. Controls were administered maltose-dextrin in amounts isocaloric to ET and/or sodium bitartrate. A fifth suckled-control group was reared normally. NIC accelerated eye opening on PD 14; whereas ET delayed eye opening and hindlimb support on PD 16. Beginning in postnatal week 7, rats were tested on a spatial delayed matching-to-place (DMP) version of the Morris water maze, which entailed a series of problems, each consisting of search and recall trials, that required the rats to use extra-maze cues to locate a hidden escape platform. In Phase 1 of testing, the ET-exposed groups were impaired in the recall trials, but there was no effect of NIC. A longer encoding time (45 vs. 10 s) improved performance across all groups. In contrast, acute administration of NIC (0.1 mg/kg ip) immediately prior to testing in Phase 2 failed to improve performance in any group. In conclusion, these results confirm previous findings of impaired spatial DMP-task performance in ET-exposed rats and further suggest that these memory deficits are amenable to amelioration.

Animals↗

PubMed2001

[Influence of fluid shear stress on the expression of monocyte chemotactic protein-1 by vascular endothelial cells].

OBJECTIVE: To study the effect of fluid shear stress on the expression of monocyte chemotactic protein-1(MCP-1) by vascular endothelial cells and its role in the early stages of atherogenesis(AS). METHODS: Parallel plate flow chamber was used to expose vascular endothelial cells to different shear stress. Sandwich ELISA (enzyme-linked immunosorbent assay) and RT-PCR (reverse transcription polymerase chain reaction) were applied to detect MCP-1 protein and mRNA respectively. RESULTS: Under 0.72 Pa shear stress, MCP-1 mRNA expression in endothelial cells reached a high level in 5 hours, but decreased to below the control level (P < 0.001) after 12 hours. The expression of MCP-1 mRNA showed a time dependent increase, which became slower 5 hours later. When different shear stress (0.30, 0.72, 2.40 Pa) was loaded for the same period of time (5 h), MCP-1 increased to above twice the control level, while its mRNA expression increased threefold as compared to the static control. CONCLUSIONS: The expression of MCP-1 reacts strongly to fluid shear stress. The steady laminar flow down regulates the gene expression of MCP-1. These results may help to explain why AS lesions tends to occur at the site of turbulent blood flow.

Cells, Cultured↗

PubMed2001

Heart rate variability and its response to thyroxine replacement therapy in patients with hypothyroidism.

OBJECTIVE: To analyze heart rate variability (HRV) and its changes with thyroxine treatment in patients with hypothyroidism. METHODS: HRV was analyzed using 24-hour electrocardiographic recording in 38 patients with hypothyroidism and 21 normal controls. The changes in HRV were evaluated for the 18 hypothyroid patients after 3 months of thyroxine therapy. RESULTS: The time domain measurements of HRV in hypothyroid patients were much lower than those in the control group. As to HRV frequency domain, the high frequency power was significantly higher, but the ratio of low frequency power to frequency power for hypothyroid patients was lower than in the controls. These abnormal changes of HRV measurements in hypothyroid patients were improved after treatment with thyroxine and were associated with recovery of serum concentrations of FT3 and FT4. CONCLUSIONS: Patients with hypothyroidism often have autonomic neuropathies with a higher level of vagal tone. These abnormalities could be partly improved by thyoxine therapy.

Adult↗

PubMed2001

[Studies on the spatial and familial aggregation of double Y nuclear family in gastric cancer pedigree].

OBJECTIVE: To explore whether there existed spatial and familial aggregation in gastric cancer in Yangzhong City of Jiangsu Province. METHODS: Using the data collected from cancer incidence registry and report system in Yangzhong City and newly designed investigation for double Y nuclear family, a genetic epidemiological study was conducted in 448 nuclear pedigrees with gastric cancer and 437 control pedigrees, involving 5 242 family members. RESULTS: Chi square test of goodness-of-fit for Poisson distribution showed there was difference between real incidence rate of gastric cancer in all townships and towns in Yangzhong and expected distribution, with chi(2) = 191.07, P < 0.001. The highest rate was in Sanyao, Changhong and Youfang townships, which was 2.2 times higher as that in the areas with low-incidence rate. Prevalence rate of gastric cancer was significantly higher in the siblings (5.42%) and parents (8.65%) of the probands, than that in siblings and parents of their spouses (4.94% and 3.20%, respectively). Prevalence rate of gastric cancer in the offspring with both parents suffered from gastric cancer was the highest, 22.58%. Test for goodness-of-fit of binominal distribution showed that there was significant difference between observed number and expected number of pedigrees with gastric cancer, with P < 0.0001. CONCLUSION: There was not only significantly spatial aggregation of gastric cancer in Yangzhong City, but also familial aggregation, which coincided with a mode of multi-genetic inheritance based on preliminary results and laid a foundation for exploring the difference in gentic susceptibilities and environmental factors for gastric cancer in Yangzhong City.

China↗

PubMed2001

[HIV genomic mutation on antiretroviral therapy].

BACKGROUND: To study the characteristics of HIV genomic mutation on antiretroviral therapy. METHODS: HIV DNA and HIV RNA were detected by using Taq-PCR, RT-PCR, LD-PCR, hybridization, and oligonucleotide 32P- probes against gag, tat, nef, LTRU3, etc. RESULYS: The HIV RNA load in serum declined significantly, CD4 lymphocyte count increased, copies of gag region of HIV DNA decreased, and full-length HIV DNA disappeared. Bands showing gag segments hybridized with 32P-probe appeared negative or less clear in some cases after antiretroviral therapy. However, the regions hybridized with probes Xho-nef and LTR U5 were apparently enhanced and some drawbands were seen. CONCLUSIONS: HIV gene may experiece obvious mutation on antiretroviral therapy.

Adult↗

PubMed2001

[Study on HIV DNA of epidemic HIV-1 strains].

OBJECTIVE: To study the characteristics of variation of HIV DNA in prevalent HIV-1 strains. METHODS: HIV DNA, extracted from peripheral blood mononuclear cell(PBMC) in 63 patients infected with HIV, was investigated by reverse-transcript PCR (RT-PCR), Long-Distance PCR(LD-PCR), molecular cloning hybridization and sequencing, respectively. RESULTS: The subtypes were identified in 57 samples. Subtype B was identified in 43 cases, subtype C in 5 and subtype E in 9. It was found that both full-length and defective HIV DNA in 31 out of 57 cases, defective HIV DNA in 19 cases and full-length HIV DNA in 7 cases. The deleted regions of genome were from 71 to 7,759 nucleotides. CONCLUSION: The variation of gene segments of HIV DNA plays an important role in the infection and epidemic of HIV.

Adult↗

PubMed2001

[Study on DNA oxidative damage of O3 aging model in mice].

OBJECTIVE: This study was aimed to detect the animals' DNA oxidative damage. METHODS: A free radical mouse aging model was established by putting the mouse in a device for inhaling quantities of ozone (O3). Single cell gel electrophoresis (SCGE) was used for assessing the splenolymphocytes' DNA damage. RESULTS: The appearance rate of comet and the length grade of DNA migration for the young control group (P < 0.05). No significant difference in the degree of DNA damage was observed between the O3 model group and the natural aging group(P > 0.05). CONCLUSION: The DNA damage of O3 animal model is consistent with that of natural aging animal; this animal model DNA damage of O3 animal model is consistent with that of natural aging animal; this animal model and the method of SCGE are useful for future researches on aging and antiaging medicine.

Aging↗

PubMed2000

14-3-3 proteins block apoptosis and differentially regulate MAPK cascades.

14-3-3 family members are dimeric phosphoserine-binding proteins that participate in signal transduction and checkpoint control pathways. In this work, dominant-negative mutant forms of 14-3-3 were used to disrupt 14-3-3 function in cultured cells and in transgenic animals. Transfection of cultured fibroblasts with the R56A and R60A double mutant form of 14-3-3zeta (DN-14-3-3zeta) inhibited serum-stimulated ERK MAPK activation, but increased the basal activation of JNK1 and p38 MAPK. Fibroblasts transfected with DN-14-3-3zeta exhibited markedly increased apoptosis in response to UVC irradiation that was blocked by pre-treatment with a p38 MAPK inhibitor, SB202190. Targeted expression of DN-14-3-3eta to murine postnatal cardiac tissue increased the basal activation of JNK1 and p38 MAPK, and affected the ability of mice to compensate for pressure overload, which resulted in increased mortality, dilated cardiomyopathy and massive cardiomyocyte apoptosis. These results demonstrate that a primary function of mammalian 14-3-3 proteins is to inhibit apoptosis.

14-3-3 Proteins↗

PubMed2000

14-3-3 proteins: regulation of subcellular localization by molecular interference.

14-3-3 family of proteins plays a key regulatory role in signal transduction, checkpoint control, apoptotic, and nutrient-sensing pathways. 14-3-3 proteins act by binding to partner proteins, and this binding often leads to the altered subcellular localization of the partner. 14-3-3 proteins promote the cytoplasmic localization of many binding partners, including the pro-apoptotic protein BAD and the cell cycle regulatory phosphatase Cdc25C, but they can also promote the nuclear localization of other partners, such as the catalytic subunit of telomerase (TERT). In some cases, 14-3-3 binding has no effect on the subcellular localization of a partner. 14-3-3 may affect the localization of a protein by interfering with the function of a nearby targeting sequence, such as a nuclear localization sequence (NLS) or a nuclear export sequence (NES), on the binding partner.

14-3-3 Proteins↗

PubMed2000

Characterization of a virtually full-length human immunodeficiency virus type 1 genome of a prevalent intersubtype (C/B') recombinant strain in China.

A molecular epidemiology study was conducted among more than 100 human immunodeficiency virus type 1 (HIV-1) subtype C seropositive intravenous drug users (IDUs) from China. Genotyping based on the envelope C2V3 coding region revealed the highest homology of the most prevalent virus strains circulating throughout China to subtype C sequences of Indian origin. Based on these results, a virtually full-length genome representing the most prevalent class of clade C strains circulating throughout China was directly amplified from peripheral blood mononuclear cells of a selected HIV-infected IDU and subcloned. Sequence analysis identified a mosaic structure, suggesting extensive intersubtype recombination events between genomes of the prevalent clade C and (B')-subtype Thai virus strains of that geographic region. Recombinant Identification Program analysis and phylogenetic bootstrapping suggested that there were 10 breakpoints (i) in the gag-pol coding region, (ii) in vpr and at the 3' end of the vpu gene, and (iii) in the nef open reading frame. (B')-sequences therefore include (i) several insertions in the gag-pol coding region; (ii) 3'-vpr, the complete vpu gene, and the first exons of tat and rev; and (iii) the 5' half of the nef gene. Breakpoints located in the vpr/vpu coding region as well as in the nef gene of 97cn54 were found at almost identical positions of all subtype C strains isolated from IDUs living in different areas of China, suggesting a common ancestor for the C/B' recombinant strains. More than 50% of well-defined subtype B-derived cytotoxic T-lymphocyte epitopes within Gag and Pol and 10% of the known epitopes in Env were found to exactly match sequences within in this clade C/B' chimeric reference strain. These results may substantially facilitate a biological comparison of clade C-derived reference strains as well as the generation of useful reagents supporting vaccine-related efforts in China.

Amino Acid Sequence↗

PubMed2000

A fluorescent reporter assay for the detection of ligands acting through Gi protein-coupled receptors.

Accompanying the advances in basic biology of G protein-coupled receptors (GPCRs) is the practical need among biopharmaceutical companies for sensitive assays to assess GPCR function, particularly formats that are compatible with high-throughput drug screening. Here we describe a novel cell-based assay format for the high-throughput detection of ligands for Gi protein-coupled receptors. Two Gi-GPCRs, mu-opioid receptor (mu-OPR) and 5-hydroxytryptamine receptor la (5HT1aR) are employed as model receptor targets. The key feature of this assay system is the isolation of stable, clonal Chinese hamster ovary (CHO) cell lines that carry three separate expression plasmids: (1) a chimeric Gq/i5 protein (which re-directs a negative Gi-type signal to a positive Gq-type response), (2) a given Gi-GPCR, and (3) a beta-lactamase (beta1a) reporter gene responsive to Gi-GPCR signaling. Cell-based assays built using this format show appropriate rank order of potency among a reference set of receptor agonist and antagonist compounds. Such assays are also robust, reliable, and can be used for industrial-scale applications such as high-throughput screening for drug leads.

Animals↗

PubMed2000

[Molecular epidemiological study on HIV-1 infection in Shandong Province].

OBJECTIVE: The aim of this study was to understand the distribution of HIV-1 strain subtypes and their variation in Shandong Province and to analyze their source and predict their epidemic trend. METHODS: We collected the whole blood from 25 anti-HIV-1 antibody positive cases and separated the peripheral blood mononuclear cells. The provirus DNA was extracted and amplified by nested-PCR, after which the HIV-1 membrane protein gene (env) C2-V3 region was sequenced and its subtype was analyzed. RESULTS: Among 25 HIV-1 antibody positive cases, 24 HIV-1 env gene fragments were amplified and analyzed.5 subtypes of Group HIV-1 M were identified among these cases,that are subtypes A, B, B', C and E. 13 occupational blood donors were all classified as subtype B' (Thailand B'). A, B, C or E subtypes were discovered in 10 returned laborers working abroad and 1 female spouse of one laborer. CONCLUSIONS: The condition of HIV-1 subtype infection was complicated in Shandong Province. So, it is important to strengthen the surveillance and control of HIV-1 subtype strain infection in high risk populations especially the occupational blood donors and returned laborers working abroad to prevent its spread in Shandong Province.

Adult↗