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Biomedical subjects

X Pei

Publications and source records attributed to X Pei.

At least 19 recordsLinked to original sources
PubMed2006

Provincial income inequality and self-reported health status in China during 1991-7.

BACKGROUND: The relationship between income inequality and health has been widely explored. Today there is some evidence suggesting that good health is inversely related to income inequality. After the economic reforms initiated in the early 1980s, China experienced one of the fastest-growing income inequalities in the world. The state of China in the 1990s is focussed on and possible effects of provincial income inequality on individual health status are explored. METHODS: A multilevel regression model is used to analyse the data collected in 1991, 1993 and 1997 from nine provinces included in the China Health and Nutrition Survey. The effects of provincial Gini coefficients on self-rated health in each year are evaluated by two logistic regressions estimating the odds ratios of reporting poor or fair health. The patterns of this effect are compared among the survey years and also among different demographic groups. RESULTS: The analyses show an independent effect of income inequality on self-reported health after adjusting for individual and household variables. Furthermore, the effect of income distribution is not attenuated when household income and provincial gross domestic product per capita are included in the model. The results show that there is an increased risk of about 10-15% on average for fair or poor health for people living in provinces with greater income inequalities compared with provinces with modest income inequalities. CONCLUSIONS: In China, societal income inequality appears to be an important determinant of population health during 1991-7.

China↗
PubMed2005

SU proteins from virulent and avirulent EIAV demonstrate distinct biological properties.

Biologic activity of equine infectious anemia virus (EIAV) surface (SU) glycoprotein was assayed in a mouse model. Recombinant SU from virulent EIAV17 (SU17), administered intraperitoneally to mouse pups, induced dose-dependent diarrheal responses similar to those reported for SIV SU (Virology 277 (2000) 250). SU17 caused fluid accumulation without histological lesions in mouse intestinal loops, induced chloride secretory currents in Ussing chambers and increased inositol 1,4,5 triphosphate (IP3) levels in HT29 cells. An SU17 peptide, SU17(299-330), provoked a dose-dependent diarrheal response akin to enterotoxic peptides from SIV. In contrast, SU from an avirulent EIAV strain failed to induce a dose response in mouse pups and produced lower levels of activity than SU17 in Ussing chambers and IP3 assays. These results demonstrate that a mouse pup model is useful to monitor EIAV SU biologic activity, showing clear differences between the activities of SU derived from virulent and avirulent viruses, and may provide a useful screen of EIAV virulence.

Amino Acid Sequence↗
PubMed2005

Humanin delays apoptosis in K562 cells by downregulation of P38 MAP kinase.

Humanin (HN) is a newly identified neuroprotective peptide. In this study, we investigated its antiapoptotic effect and the potential mechanisms in K562 cells. Upon serum deprivation, expression of HN in K562 cells decreased and its intracellular distribution changed from cytoplasm to cell membrane. In HN stably transfected K562 cells, apoptosis was delayed compared with control vector transfected cells as measured by flow cytometry. Furthermore, analysis of different mitogen-activated protein (MAP) kinases activity revealed that extracellular signal-regulated kinase (ERK) pathway was inhibited while p38 signaling was activated following serum deprivation in K562 cells. And in HN transfected K562 cells, ERK downregulation was not affected, but p38 activation was suppressed, which may responsible for the delayed apoptosis in these cells. Activation of the ERK signaling pathway by phorbol myristate 13-acetate (PMA) and sorbitol protected K562 cells from serum deprivation induced apoptosis. Additionally, overexpression of HN reduced megakaryocytic differentiation of K562 cells. The present data outline the role of ERK and p38 MAP kinases in serum deprivation induced apoptosis in K562 cells and figure out p38 signaling pathway as molecular target for HN delaying apoptosis in K562 cells.

Apoptosis↗
PubMed2001

[The study of beta-2 adrenergic receptors gene transferred into cardiomyocytes by adenovirus vectors contain different promoter].

OBJECTIVE: To observe human beta(2) adrenergic receptors (beta(2)-AR) gene expression in cardiomyocytes transfected by adenoviral vector contain cmv or mlc-2v promoter. METHODS: Two adenoviral vectors (Adcmv beta(2) AR, Admlc beta(2) AR) were constructed, in which beta(2)-AR gene is under control of either the ventricle-specific myosin light chain-2 (mlc-2v) or the cmv promoter. The cultured neonate rat ventricular myocytes were infected by two adenoviral vectors, and the beta(2)-AR expression of on cultured neonate rat ventricular myocytes and their ability to potentiate beta-adrenergic signaling were assessed. RESULTS: The presence of beta(2)-AR mRNA was detected by RT-PCR, and the expression of the beta(2)-AR gene was demonstrated by protein immunoblots. According to a ligand binding assay, the density of beta-AR in the cardiomyocytes infected by Admlc beta(2) AR and Adcmv beta(2) AR was greater than that in the control. Moreover, the latter was higher than the former (234 +/- 6.4 fmol/mg protein vs 153 +/- 5.2 fmol/mg protein) (P < 0.01). It was demonstrated that beta(2)-AR gene significantly increased isoproterenol stimulated cAMP in cardiomyocytes. CONCLUSION: The results above demonstrated that human beta(2)-AR gene was expressed in the cardiomyocytes infected by recombinant adenovirus contain cmv or mlc-2v promoter, but both is different.

Adenoviridae↗
PubMed2001

Paddlefish strike at artificial dipoles simulating the weak electric fields of planktonic prey.

The freshwater paddlefish Polyodon spathula (Polyodontidae) feeds primarily on the water flea (Daphnia sp.), and previous studies suggest that these fish detect their planktonic prey using their rostral electrosensory system. Zooplankton produce direct-current and oscillating alternating-current electric fields containing multiple frequencies and amplitudes. We asked whether an inanimate electric field is sufficient to elicit paddlefish strikes equivalent to their feeding behavior. Juvenile paddlefish respond to artificial dipole stimuli by investigating the electric field and striking at the dipole electrode tips. These behavioral responses, scored as strikes, exhibit a bandpass characteristic with a maximum response between 5 and 15 Hz. Responses were less frequent at higher (20, 30, 40, 50 Hz) and lower (0.1, 0.5, 1 Hz) test frequencies, with a steep drop-off below 5 Hz. Strike rates also varied with stimulus intensity. Response frequency was greatest at 0.25 microA peak-to-peak amplitude, with reduced responses at lower and higher amplitudes (0.125 and 1.25 microA). Striking behavior was also influenced by water conductivity: strike rate was reduced at higher water conductivity. Dipole-elicited strikes exhibit behavioral plasticity. Fish habituate to repetitive dipole stimuli that are not reinforced by prey capture, and they dishabituate after food reinforcement. These experiments characterize paddlefish feeding strikes towards dipole electrodes at signal frequencies and intensities simulating the electric fields of zooplankton, their natural prey, and demonstrate that electric fields are sufficient to elicit feeding behavior. The results support the conclusion that paddlefish use their passive electrosensory system for planktivorous feeding.

Animals↗
PubMed2001

[Expression of recombinant human Flt3 ligand in Escherichia coli and its purification and characterization].

OBJECTIVE: To establish a highly efficient expression system of recombinant human Flt3 ligand (rhFL) in E. coli and a suitable purification method of the expressed products. METHOD: Human FL encoding cDNA was introduced into pProEXHT plasmid to express a 6 x His-FL fusion protein in E. coli. The fusion protein expressed in inclusion body was isolated, solubilized and refolded, and then purified by chromatography on a metal-chelating affinity column (MCAC). Its activity was detected by stimulating the proliferation of CD(34)(+) cells. RESULT: The amount of rhFL expressed was about 15% of total bacterial proteins and the purity of rhFL was 90% after MCAC. The combination of rhFL, granulocyte colony-stimulating factor and erythropoietin could stimulate CD(34)(+) cells to a 400 fold expansion. CONCLUSION: The purified rhFL had a potent activity to stimulate hematopoietic stem cells to expanse in vitro.

Cell Proliferation↗
PubMed2000

[Epidemiological studies on the relationship between body weight and the prevalence rate of impaired glucose tolerance (IGT) in the population of urban areas of Tianjin city].

OBJECTIVE: In order to explore the relationship between body weight and the prevalence rate of IGT in a community - based population and to provide scientific informations of IGT for prevention and control. METHODS: Cluster sampling was carried out in prevalence survey, together with clinical examination and test of blood plasma glucose. RESULTS: A sample of 62,577 people was performed by cluster random sampling. Results showed that the crude prevalence rate of IGT in the whole population of three communities was 13.13 per thousand in males, 19.18 per thousand in females, and 16.23 per thousand in both sexes respectively. The IGT prevalence rate of different body weight group in community population had a marked difference. There was a trand that the IGT prevalence rate increased markedly with the increase of body weight. CONCLUSION: The incidence of IGT is related to body weight and obesity.

Adolescent↗
PubMed2000

[Expression of lipofect AMINE mediated human GM-CSF eukaryotic expressing vector in HFCL cells].

OBJECTIVE: To construct an eukaryotic expressing vector-pIRES1neo/hGM-CSF and express it in human bone marrow stromal cell line HFCL. METHODS: Human granulocyte/macrophage colony-stimulating factor cDNA (hGM-CSF cDNA, 751 bp) was inserted into an effective eukaryotic expressing vector-pIRES1neo which contains the human cytomegalovirus (CMV) major immediate early promoter/enhancer and the internal ribosome entry site (IRES) of the encephalomyocarditis virus (ECMV). HFCL cells were transfected with the recombinant vector pIRES1neo/hGM-CSF by liposome-mediated gene transfer method. Integration of hGM-CSF in the genome, transcription of its mRNA and expression of its protein in the transfected HFCL cells were assayed by Southern blot, Northern blot, ELISA and hGM-CSF dependent cell line TF-1. RESULTS: hGM-CSF cDNA was integrated into HFCL genome successfully, hGM-CSF mRNA was transcripted and hGM-CSF protein was expressed of (56.9 +/- 0.7) ng/10(6) cells by ELISA and (6.56 +/- 0.16) x 10(3) U/10(6) cells per day by TF-1 cell assay in the supernatant. CONCLUSION: The recombinant vector is proved to be stably expressed in HFCL cells and the biological activity of hGM-CSF was detectable in the supernatant of the transfected cells.

Blotting, Northern↗
PubMed2000

[Experimental studies on the characteristics of suicide gene system HSV-tk/GCV and its effect on dendritic cells].

OBJECTIVE: To study the characteristics of suicide gene system of the herpes simplex virus thymidine kinase (HSV-tk) gene in tumor cells and explore the apoptosis phenomena in this system and its effect on dendritic cells (DC). METHOD: HSV-tk was transduced into the breast cancer cell line MCF-7 cells with a retrovirus vector. Apoptosis was examined by electro-microscopy and FACS. DCs were induced from cord blood CD(34)(+) cells with a combination of cytokines (GM-CSF, TNF-alpha, SCF and FL) and (3)H-TdR was adopted to determine the proliferation of T cells. RESULTS: In vitro experiment showed a dose-dependent cell killing of the HSV-tk gene transducted cells on ganciclovir (GCV) treatment. The apoptosis rate increased to 31.3% from the control group of 19.3%. Apoptosis is the important mechanism in bystander effect of HSV-tk/GCV system. The CD(1a)(+) and HLA-DR(+) cells in the induced DC were of (27.18 +/-1.56)% and (93.7 +/- 1.0)%, respectively. Co-incubation of DC with apoptotic cells further stimulated the proliferation of T cells. CONCLUSION: It suggested that HSV-tk/GCV system, alone or combined with radiotherapy, be a promising suicide gene therapy for cancer patient and an approach to enhancing DC function.

3T3 Cells↗
PubMed1999

The in vitro antiapoptotic effect of dehydroepiandrosterone sulfate in mouse thymocytes and its relation to caspase-3/caspase-6.

The effects of dehydroepiandrosterone sulfate (DHEAS) on thymocyte apoptosis induced by dexamethasone (DEX) were investigated. Apoptosis was measured by using agarose gel electrophoresis of DNA, the terminal deoxynucleotidyltransferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay and flow cytometry. Our results showed that preincubation with 1 x 10(-4) M DHEAS protected thymocytes from DEX-induced apoptosis in vitro. Moreover, we found no blocking effect on the DEX-induced activation of caspase-3 and caspase-6 by the preincubation of thymocytes with DHEAS. This may be interpreted to mean that the antagonism of DHEAS to DEX-induced apoptosis is not related to the activation of these down-stream caspases which play a critical role in the execution of apoptosis.

Animals↗
PubMed1999

Old age support in China: the role of the state and the family.

This study investigates the relationship between some support factors and the well-being of the elderly in China. The analytical models identify and compare the effects of each type of factor on the sense of well-being of elderly Chinese across rural and urban settings. Pension, health care, size of family, and living arrangements are the factors found to be significantly related to the perception of happiness among aged people in general. The strength of the effects of children and living arrangements varies depending on places of residency. The findings indicate the continuous role of the family support, and the increasingly important role of state support in promoting a sense of well-being among elderly Chinese.

Aged↗
PubMed1999

Who is hematopoietic stem cell: CD34+ or CD34-?

Hematopoietic stem cells (HSC) possess multipotentiality, enabling them to self-renew and also to produce mature blood cells, such as erythrocytes, leukocytes, platelets, and lymphocytes. CD34 is a marker of human HSC, and all colony-forming activity of human bone marrow (BM) cells is found in the CD34+ fraction. Clinical transplantation studies that used enriched CD34+ BM cells indicated the presence of HSC with long-term BM reconstitutional ability within this fraction. But recent studies in NOD/SCID mice, rhesus monkeys, and human/sheep competitive engraftment models have provided evidence for the presence of a rare cell population that contains progenitors capable of producing CD34+ cells in vitro. These progenitors are highly enriched in HSC and have competitive long-term in vivo repopulating potential devoid of both CD34 and lineage-marker expression. These new findings add to the growing evidence that some stem cells in the BM do not express the CD34 marker, which is currently used to select stem cells for transplantation.

Animals↗
PubMed1999

[Engineering of hematopoietic cells and the hematopoietic reconstitution of expanded cells in SCID mice].

OBJECTIVE: To elucidate the roles of cytokines for ex vivo expansion and orderly differentiation of hematopoietic progenitor cells, and the capacity of hematopoietic reconstitution of the expanded cells. METHODS: CD34+ cells were isolated from umbilical cord blood by using a high-gradient magnetic cell sorting system (MACS), and expanded with the different combinations of cytokines in a liquid culture system. The expanded cells were then transplanted into sublethally irradiated SCID mice. RESULTS: The combination of cytokines including FL, SCF, TPO, etc. increased total cells, progenitor cells(CFU-GM and CFU-MK), and CD34+ CD38- early progenitor cells by (2,130 +/- 57), (70 +/- 7), (118 +/- 11) and (46 +/- 5) folds, respectively. The percentage of dendritic cells (24.3 +/- 2.1)% was also much higher than the control(0.4 +/- 0.3)%. The CD34+ CD38- subsets and the combination of FL and TPO were identified as the most potential for expanding early progenitor cells. The expanded cells could smoothly engraft SCID recipients and reconstitute their hematopoiesis. Furthermore, human hematopoietic cells and could be detected in marrow cells from SCID mice transplanted 6 weeks late. CONCLUSIONS: It is possible to expand hematopoietic cells ex vivo efficiently and maintain the hematopoietic reconstitution capacities of hematopoietic stem/early progenitor cells by an appropriate combination of cytokines. The engineering of hematopoietic cells--the new generation of cellular therapeutics are now underway in the applications of stem cell transplantation, immunotherapy of cancers, and gene therapy.

Animals↗
PubMed1999

[Effect of WT1 antisense oligonucleotide on proliferation and apoptosis of human leukemia cells].

OBJECTIVE: To elucidate the effect of WT1 antisense oligonucleotide on and the role of WT1 gene in proliferation and apoptosis of leukemia cells. METHODS: K562, U937, HL-60 cell lines, leukemic blast from 8 acute myeloid leukemia patients and normal bone marrow cells from 8 healthy subjects were treated in vitro with WT1 antisense oligonucleotide (WT1 ASO) targeting to the translation site of WT1 mRNA. The inhibitory effect on growth of leukemia cells was measured by Trypan blue exclusion and colony-forming unit assay. Apoptosis was measured by flow cytometric analysis and DNA fragmentation assay. RESULTS: WT1 ASO significantly inhibited the proliferation of K562 cells expressing WT1 and leukemic blast of 4 in 8 acute myeloid leukemia patients, but didn't inhibit the growth of U937 cells which had no WT1 expression and CFU-GM of normal marrow cells from 8 healthy subjects. Whereas WT1 sense oligonucleotide (WT1 SO) had no effect on the proliferation of K562 cells, U937 cells and the CFU-GM of normal marrow cells. WT1 ASO could induce apoptosis of K562 cells and the level of apoptosis was increased markedly when combined with Vp16; WT1 ASO alone couldn't induce apoptosis of HL-60 cells, but could increase the apoptosis when combined with Vp16. CONCLUSION: WT1 ASO specifically inhibit the growth of leukemic cells, induce apoptosis of K562 cells and increase the apoptosis susceptibility of leukemia cells to Vp16. WT1 plays an important role in proliferation and apoptosis of leukemic cells.

Acute Disease↗
PubMed1999

[Studies on hematopoietic reconstitution by ex vivo expanded human cord blood hematopoietic stem/progenitor cells in SCID mice].

OBJECTIVE: To elucidate the effect of the combination of cytokines on ex vivo expansion and self-renewal potential of human umbilical cord blood hematopoietic stem/progenitor cells. METHODS: CD34+ cells from cord blood were expanded for 14 days in the culture containing FL + Tpo + SCF + IL-6 + IL-3 + G-CSF and the expanded cells were transplanted into sublethally irradiated SCID mice. RESULTS: The expanded cells were engrafted smoothly in the SCID recipients and reconstituted their hematopoiesis. Furthermore, human hematopoietic cells could be detected in the marrow of the recipients 6 weeks after transplantation. CONCLUSION: It is possible to expand hematopoietic cells ex vivo efficiently and maintain concomitantly their self-renewal and hematopoietic reconstitution capacities by the combination of FL + Tpo + SCF + IL-6 + IL-3 + G-CSF.

Animals↗
PubMed1999

[Studies on the properties of dendritic cells from cord blood CD34+ cells and peripheral blood monocytes].

OBJECTIVE: Ex vivo expansion and purification of dendritic cells(DC) with typical phenotype, morphology and function are critical to the further studies on DC and their clinical application. METHODS: CD34+ cells were isolated from umbilical cord blood by using a high-gradient magnetic cell sorting system (MACS), and peripheral blood mononuclear cells (PBMC) were depleted of T and B cells by mixing them with T/CD2 and B/CD19 magnetic beads. DC were induced and expanded with different combinations of cytokines. They were identified for their properties by FACS, electronic microscopy, microscopy, and mixed lymphocyte reaction (MLR). RESULTS: Cultures of cord blood CD34+ cells with the combination of GM-CSF + TNF-alpha + SCF + FL yielded (27.18 +/- 1.56)% CD1a+ cells, much higher than that (0.65 +/- 0.38)% with GM-CSF alone. The combination of GM-CSF and high dose IL-4(1,000 U/ml) was the most potential for expanding CD1a+ cells [(21.8 +/- 0.32)%] for PBMC. Both of the DC from different sources were similar in phenotype and morphology, and had the capacity to stimulate proliferation of allogeneic T lymphocytes. CONCLUSION: Both of cord blood and peripheral blood are the source for generation of a large number of typical DC, and can be adopted for the application according to different purposes. These results lay foundation for the immunotherapy with DC.

Antigens, CD34↗
PubMed1999

[Retroviral-mediated transfer of a hygromycin phosphotransferase-thymidine kinase fusion gene into human bladder carcinoma cell].

OBJECTIVE: To evaluate the therapeutic efficacy of retroviral-mediated hygromycin phosphotransferase-thymidine kinase fusion gene (HyTK)/GCV on human bladder carcinoma cell. METHODS: A retroviral expression vector pL (HyTK) SN was constructed. By using FuGENE 6-mediated transfection and "ping-pong effect" technique, high-titer of retroviral supernatant was obtained and HyTK gene was transferred into EJ cells. A retroviral vector encoding, enhanced green fluorescent protein, EGFP was used to rapidly detect the transduction efficiency. Antitumor effects were observed after GCV treatment. RESULTS: In vitro experiments demonstrated the EJ cells transferred by HyTK gene were killed in the GCV treatment. Non-transduced parental cells were not sensitive to GCV, but they were dead by the bystander killing of neighboring cells when mixed with EJ/HyTK cells at various ratios. In addition, this not only affect wild-type EJ cells but also cells from different bladder carcinoma cell lines. CONCLUSIONS: Retroviral-mediated HyTK/GCV systems were a promising suicide gene therapy for bladder carcinoma. EGFP may act as a convenient and rapid reporter to monitor retroviral-mediated gene transfer and expression in bladder carcinoma cells.

Antiviral Agents↗