Biomedical subjects

Wei Shi

Publications and source records attributed to Wei Shi.

At least 109 records · Page 6Linked to original sources

PubMed2003

Dysregulated PTEN-PKB and negative receptor status in human breast cancer.

Recent studies demonstrate that abnormalities in PTEN may be one of the most frequent genetic events observed in human cancers. PTEN dysfunction leads to tumorigenesis through unopposed survival signals mediated via activated protein kinase B (PKB), which may also be associated with hormone-independence. We therefore investigated the relationship between PTEN-PKB and receptor status in human breast cancer. Several molecular variables, including immunohistochemical staining for PTEN, PKB (phosphorylated on ser473), p53 and p21 were evaluated. The p53 gene was sequenced from exons 2-11. Seventy-eight participants in a randomised breast cancer trial served as the cohort for our study. Twenty-eight of 77 (36%) patients' tumours demonstrated absent or reduced PTEN expression; 17 of 78 (22%) tumours over-expressed P-PKB. A significant inverse relationship was observed between reduced PTEN and increased P-PKB expression. Reduced PTEN also correlated with reduced ER or PR expression. None of the molecular variables correlated with survival. ER and PR negative tumours, however, experienced a significantly inferior disease-free survival than other ER/PR status tumours. Immunohistochemical analyses of ER expression in mammary carcinomas arising in PTEN heterozygous knockout mice did not demonstrate a reduction in ER immunoreactivity, in comparison to wild-type mice. Our data demonstrate that the PTEN-PKB pathway is abnormal in approximately 1/3 of lymph node negative breast cancer. Dysregulated PTEN-PKB was also associated with reduced ER/PR expression, but this does not appear to be a simple direct causal relationship. These observations support the contention that dysregulation in PTEN-PKB contributes to disease progression and hormone resistance of human breast cancer.

Aged↗

PubMed2003

Induction of a senescent-like phenotype does not confer the ability of bovine immortal cells to support the development of nuclear transfer embryos.

Previously, we reported that cloned embryos derived from an immortalized bovine mammary epithelial cell line (MECL) failed to develop beyond 12- to 16-cell stage. To analyze whether induction of a senescent-like phenotype in MECL can improve their ability to support the development after transfer into enucleated oocytes, we treated MECL with DNA methylation inhibitor 5-aza-2-deoxycytidine (Aza-C), histone deacetylase inhibitors trichostatin A (TSA), sodium butyrate (NaBu), or 5-bromodeoxyuridine and used those cells for nuclear transfer. Primary bovine fetal fibroblasts (BFF) were used as control. All agents were capable to induce features of senescence including reduced cell proliferation, enlarged cell size with a considerable proportion of cells stained positive for acidic senescence-associated beta-galactosidase and G1/S cell cycle boundary arrest in MECL. Aza-C treatment induced genome demethylation. Acetylation of H3 and H4 was increased after TSA treatment in both MECL and BFF, whereas no obvious changes in global H3 or H4 acetylation were detected after NaBu treatment. Nuclear transfer experiments following diverse treatments demonstrated that the induced senescent-like phenotype of MECL did not confer their ability to support embryonic development, although 7.3% of reconstructed embryos derived from NaBu-treated cells developed to morula stage. Intriguingly, a much higher proportion of cloned embryos developed to blastocysts when using NaBu-treated BFF, compared with using untreated BFF (59% versus 26%). Our results suggest that the developmental failure of donor nuclei from bovine immortal cells could not be reversed by induction of senescent-like phenotype. The beneficial effect of NaBu on the developmental potential of cloned embryos reconstructed from BFF merits further studies.

Animals↗

PubMed2003

Oxypurinol administration fails to prevent hypoxic-ischemic brain injury in neonatal rats.

The purpose of the present study was to determine whether oxypurinol, a xanthine oxidase inhibitor, reduces free radicals and brain injury in the rat pup hypoxic-ischemia (HI) model. Seven-day-old rat pups had right carotid arteries ligated followed by 2.5h of hypoxia (8% oxygen). Oxypurinol or vehicle was administered by i.p. injection at 5 min after reoxygenation and once daily for 3 days. Brain damage was evaluated by weight deficit of the right hemisphere at 22 days following hypoxia. Oxypurinol treatments did not reduce weight loss in the right hemisphere. Brain weight loss in the right hemisphere were -26.2+/-3.6, -15.2+/-6.9, -21.7+/-4.4, -15.8+/-5.1, and -16.7+/-3.4% in vehicle (n=33), 10 (n=17), 20 (n=16), 40 (n=15), and 135 mg/kg (n=13) oxypurinol-treated groups (p>0.05), respectively. Brain thiobarbituric acid-reacting substances (TBARS) were assessed 3 and 6h after reoxygenation. Concentrations of TBARS rose 1.5-fold due to HI. Oxypurinol did not significantly reduce an HI-induced increase in brain TBARS. Thus, xanthine oxidase may not be the primary source of oxy-radicals in pup brain and as such oxypurinol does not prevent free radical-mediated lipid peroxidation or protect against brain injury in the neonatal rat HI model.

Animals↗

PubMed2003

Efficacy of targeted FasL in nasopharyngeal carcinoma.

We have successfully achieved selective gene expression in human nasopharyngeal carcinoma (NPC) by exploiting the presence of the Epstein-Barr virus (EBV), utilizing a transcriptional targeting strategy (J. H. Li et al., 2002, Cancer Res. 62: 171). Building on this platform, we have generated a novel DeltaE1 adenoviral vector mediating the expression of a mutant noncleavable form of the FasL gene (HUGO-approved symbol TNFSF6) (ad5oriP.ncFasL). We observe that this therapy induces significant cytotoxicity in the EBV-positive NPC cell line C666-1, mediated by the induction of caspase-dependent apoptosis. The addition of ionizing radiation therapy (RT) causes additional cytotoxicity. Ex vivo infection of C666-1 cells with adv.oriP.ncFasL completely prevents tumor formation in SCID mice followed for up to 100 days. The combination of intratumoral adv.oriP.ncFasL with RT causes regression of established nasopharyngeal xenograft tumors for 2 weeks' duration. Systemic delivery of this targeted strategy achieves 50-fold higher gene expression in nasopharyngeal tumors than in normal organs. Intravenously injected adv.oriP.ncFasL results in mild perturbation of liver function that returns to normal 2 weeks after initial therapy. These results demonstrate the efficacy of our EBV-specific targeting strategy, which allows the potentially safe and effective utilization of a highly potent membrane-based apoptotic gene.

Animals↗

PubMed2003

Confirmation of an acute no-observed-adverse-effect and low-observed-adverse-effect level for copper in bottled drinking water in a multi-site international study.

In a double blind, 3x3 factorial (volumexdose) study, 70 adult females (18-60 years of age) at four different international sites (total pooled n=269) were given 100, 150, or 200ml of bottled drinking water with 0.4, 0.8, or 1.2mg of copper (Cu) as the sulfate salt once each week. Two additional doses (0 and 1.6mg Cu) were added at the 200ml volume to determine a dose-response relationship and corroborate previously reported results. All subjects completed a questionnaire at 0, 0.25, and 1h post-dosing that screened for positive gastrointestinal (GI) effects (nausea, vomiting, abdominal pain, and diarrhea). Nausea was the most prevalent symptom reported and was generally reported within the first 15min (water volume, p<0.032; copper dose, p<0.0001; and water volumexcopper interaction, p<0.97). As volume increased, the effect of Cu-induced nausea decreased; as Cu dose increased, the incidence of nausea increased. At 200ml, a significant increase in reported incidence of nausea at 0.25h occurred at 1.2 mg Cu (6mg Cu/L), indicating a NOAEL of 0.8mg Cu (4mg Cu/L) for adult females. These data confirm a previously determined human acute NOAEL for Cu added to distilled water, and provide additional, controlled human data for determining safe concentrations of Cu in drinking water.

Administration, Oral↗

PubMed2003

Epigenetic reprogramming in mammalian nuclear transfer.

With the exception of lymphocytes, the various cell types in a higher multicellular organism have basically an identical genotype but are functionally and morphologically different. This is due to tissue-specific, temporal, and spatial gene expression patterns which are controlled by genetic and epigenetic mechanisms. Successful cloning of mammals by transfer of nuclei from differentiated tissues into enucleated oocytes demonstrates that these genetic and epigenetic programs can be largely reversed and that cellular totipotency can be restored. Although these experiments indicate an enormous plasticity of nuclei from differentiated tissues, somatic cloning is a rather inefficient and unpredictable process, and a plethora of anomalies have been described in cloned embryos, fetuses, and offspring. Accumulating evidence indicates that incomplete or inappropriate epigenetic reprogramming of donor nuclei is likely to be the primary cause of failures in nuclear transfer. In this review, we discuss the roles of various epigenetic mechanisms, including DNA methylation, chromatin remodeling, imprinting, X chromosome inactivation, telomere maintenance, and epigenetic inheritance in normal embryonic development and in the observed abnormalities in clones from different species. Nuclear transfer represents an invaluable tool to experimentally address fundamental questions related to epigenetic reprogramming. Understanding the dynamics and mechanisms underlying epigenetic control will help us solve problems inherent in nuclear transfer technology and enable many applications, including the modulation of cellular plasticity for human cell therapies.

Animals↗

PubMed2003

DNA methylation in placentas of interspecies mouse hybrids.

Interspecific hybridization in the genus Mus results in several hybrid dysgenesis effects, such as male sterility and X-linked placental dysplasia (IHPD). The genetic or molecular basis for the placental phenotypes is at present not clear. However, an extremely complex genetic system that has been hypothesized to be caused by major epigenetic changes on the X chromosome has been shown to be active. We have investigated DNA methylation of several single genes, Atrx, Esx1, Mecp2, Pem, Psx1, Vbp1, Pou3f4, and Cdx2, and, in addition, of LINE-1 and IAP repeat sequences, in placentas and tissues of fetal day 18 mouse interspecific hybrids. Our results show some tendency toward hypomethylation in the late gestation mouse placenta. However, no differential methylation was observed in hyper- and hypoplastic hybrid placentas when compared with normal-sized littermate placentas or intraspecific Mus musculus placentas of the same developmental stage. Thus, our results strongly suggest that generalized changes in methylation patterns do not occur in trophoblast cells of such hybrids.

Animals↗

PubMed2003

The pineapple eye gene is required for survival of Drosophila imaginal disc cells.

Each ommatidium of the Drosophila eye is constructed by precisely 19 specified precursor cells, generated in part during a second mitotic wave of cell divisions that overlaps early stages of ommatidial cell specification. Homozygotes for the pineapple eye mutation lack sufficient precursor cells due to apoptosis during the period of fate specification. In addition development is delayed by apoptosis during earlier imaginal disc growth. Null alleles are recessive lethal and allelic to l(2)31Ek; heteroallelic combinations can show developmental delay, abnormal eye development, and reduced fertility. Mosaic clones autonomously show extensive cell death. The pineapple eye gene was identified and predicted to encode a novel 582-amino-acid protein. The protein contains a novel, cysteine-rich domain of 270 amino acids also found in predicted proteins of unknown function from other animals.

Amino Acid Sequence↗

PubMed2003

Mutations in the rpoB gene of multidrug-resistant Mycobacterium tuberculosis isolates from China.

Mutations in the 81-bp rifampin resistance determining region (RRDR) and mutation V176F locating at the beginning of the ropB gene were analyzed by DNA sequencing of 86 Mycobacterium tuberculosis clinical isolates (72 resistant and 14 sensitive) from different parts of China. Sixty-five mutations of 22 distinct kinds, 21 point mutations, and 1 insertion were found in 65 of 72 resistant isolates. The most common mutations were in codons 531 (41%), 526 (40%), and 516 (4%). Mutations were not found in seven (10%) of the resistant isolates. Six new alleles within the RRDR, along with five novel mutations outside the RRDR, are reported. None of isolates contained the V176 mutation.

Alleles↗

PubMed2003

[Study on guideline of alga in source water].

Toxic bloom in the sources of drinkable water has been a public health problem. Hindered by the complicated analysis procedure, very limited efforts has been done in investigating toxin level. Patronized by the Chinese Academy of Preventive Medicine, a study on alga hygiene criteria of drinkable water sources in China was conducted. Available literature was reviewed and ecological research and toxicological tests were carried out. The criteria on alga biomass in drinkable water source was formulated by referring the criteria of microcystin--LR in drinking water recommended by WHO and Ministry of Health, China. Three kinds of criteria were worked out: primary criteria, which is to ensure safety, is 1.0 x 10(4) per liter, secondary criteria, which should be alert, is 2.1 x 10(5) per liter, and third--rate criteria, which might be toxic, is 1.2 x 10(6) per liter. It is suggested that these criteria are valuable and feasible in routine work.

Cyanobacteria↗

PubMed2003

[Study on the unscheduled DNA synthesis in primary rat hepatocyte induced by source water, tap water and active carbon-treated tap water].

To study the mutagenicity of source water with different turbidities, tap water and active carbon-treated tap water, unscheduled DNA synthesis in primary rat hepatocyte was detected. Increased unscheduled DNA synthesis was found in a dose-depend manner inducted by tap water, source water and tap water treated with 5, 10 and 15 milligrammes active carbon per liter water. The results also showed that the mutagenicity of the source water increased with the increasing of its turbidity, and mutagenicity of the tap water is higher than that of the source water as well. There was no unscheduled DNA synthesis in tap water followed by the treatment with 20 milligrammes active carbon per liter water. It is suggested that the development of the water treatment technics including sedimentation, filtration and treatment with active carbon is needed for decreasing or eliminating the mutagenicity of tap water.

Animals↗

PubMed2003

Loss of p16 expression has prognostic significance in human nasopharyngeal carcinoma.

PURPOSE: p16 is an important inhibitor of cell cycle progression; absence of p16 can thus result in increased cellular proliferation. In nasopharyngeal carcinoma (NPC), absence of p16 has been reported in association with presence of the EBV and pRb. We therefore examined p16, pRb, and EBV-encoded RNA (EBER) expression in biopsy specimens from 84 patients with newly diagnosed NPC, who were treated primarily with curative radiation therapy. Our objective was to determine whether there was a correlation between these parameters and clinical outcome in NPC. EXPERIMENTAL DESIGN: Sections were cut from archival formalin-fixed, paraffin-embedded tumor blocks from NPC patients. p16 and pRb expression were determined using polyclonal and monoclonal antibodies, respectively. The presence of EBV was determined by in situ hybridization for EBER. The percentage of positively staining tumor nuclei was scored for p16 or pRb immunoreactivity. Relative intensity and proportion of cells with EBER signals were also documented. RESULTS: p16 expression was reduced (</=5% positive immunoexpression) in 59 of 84 (70%) NPC samples; in contrast, pRb was observed in all (100%) tumors. EBER signals were detected in 67 of 83 (81%) NPC specimens. There was a weak correlation between EBER presence and loss of p16 (P = 0.1). Using a Cox regression model controlling for known prognostic parameters, such as age, weight loss, and tumor stage, complete absence of p16 expression (0%, i.e., no immunostaining identified throughout the specimen) was associated with an inferior overall survival rate (P = 0.022). In addition, EBER-positive NPC was strongly associated with improved overall survival (P = 0.005) as reported previously (Shi et al., Cancer, 94: 1997, 2002). CONCLUSION: These results provide the first evidence suggesting that inactivation of p16 appears to be a significant predictor for poor overall survival in NPC. Given that reduced p16 expression is observed in the majority of patients with NPC, this indicates that therapeutic strategies targeting the p16 pathway may be a biologically rational approach for NPC. The favorable prognostic value of EBER suggests that future clinical trials with NPC should consider stratifying for EBER status.

Adult↗

PubMed2003

IL-17 induces autoantibody overproduction and peripheral blood mononuclear cell overexpression of IL-6 in lupus nephritis patients.

OBJECTIVE: To investigate the role of IL-17 in the overproduction of autoantibodies and IL-6 overexpression by peripheral blood mononuclear cells (PBMC) of lupus nephritis (LN) patients. METHODS: Fifteen consecutively hospitalized LN patients were selected as subjects and 15 healthy adults as normal controls. PBMC were obtained by Ficoll density gradient centrifugation. IgG, anti-dsDNA antibody and IL-6 protein levels were assessed using enzyme-linked immunosorbent assays (ELISA) on the supernatant of cultured PBMC of LN patients or normal controls. IL-6 mRNA levels in PBMC were measured using reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: In medium culture, IgG, anti-dsDNA and IL-6 protein levels of the supernatant of PBMC from LN patients were significantly higher than those from normal controls (1492.1 +/- 73.2 ng/ml vs 636.7 +/- 51.9 ng/ml for IgG, 306.6 +/- 53.7 IU/ml vs 95.8 +/- 11.6 IU/ml for anti-dsDNA and 50.92 +/- 15.92 ng/ml vs 1.77 +/- 0.73 ng/ml for IL-6, all P < 0.001). In LN patients, IgG, anti-dsDNA and IL-6 protein levels were higher in the supernatants of PBMC in the IL-17-stimulated culture than the medium culture, but in normal controls, only the IL-6 protein levels were significantly higher. The increase in IgG, anti-dsDNA and IL-6 protein levels induced by IL-17 was dose-dependent and could be completely blocked by IL-17 monoclonal antibody mIgG(28) and partially blocked by dexamethasone. Similarly, IL-6 mRNA overexpression of PBMC in LN patients or normal controls induced by IL-17 was both dose- and time-dependent. During medium culture, IL-6 mRNA levels in LN patients were significantly higher than those in normal controls (1.80 +/- 0.11 vs 0.36 +/- 0.07). During stimulation with IL-17, IL-6 mRNA levels in LN patients were higher than those in normal controls (3.21 +/- 0.24 vs 1.30 +/- 0.14, P < 0.05) and also significantly higher when comparing the stimulated culture with the medium culture either in LN patients or normal control. CONCLUSIONS: IL-17 may play an important role in the pathogenesis of LN through the induction of IgG, anti-dsDNA overproduction and IL-6 overexpression of PBMC in LN patients.

Adolescent↗

PubMed2003

[Expression of CD44v6 in gastric cancer and its correlation with Helicobacter pylori infection].

BACKGROUND & OBJECTIVE: It was considered that the expression of CD44v6 in gastric cancer was high and Helicobacter pylori (HP) infection was type I carcinogen of gastric cancer. So far, no document has been reported about the relationship between HP infection and CD44v6 expression. This study was designed to investigate the relationship between expression of CD44v6 in gastric cancer and HP infection. METHODS: The specimens were divided into three groups:gastric cancer (56 cases), cancer adjacent tissue (56 cases), and gastric mucosa dysplasia (32 cases). The expression of CD44v6 was determined by reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analysis. HP was determined with the rapid urease test and Warthin-Starry staining. Simultaneously, HP cagA antibody was assayed in the serum of 56 patients with gastric cancer. RESULTS: HP positive infection group: The positive expression rates of CD44v6 in metastasis cancer (100%, 12/12) and non-metastasis cancer (90.5%, 19/21) were higher than those in paracancer tissue (48.6%, 24/35) and in gastric mucosa dysplasia (23.6%, 6/23). No statistical difference was found between non-metastasis cancer and metastasis cancer (P >0.25). But there were significant differences between gastric mucosa dysplasia and gastric cancer or cancer adjacent tissue (P< 0.005). HP negative infection group: The positive expression rates of CD44v6 in metastasis cancer, non-metastasis cancer, cancer adjacent tissue, and gastric mucosa dysplasia were 66.7%, 51.4%, 35.1%, and 18.1%, respectively; no statistical difference was found between each group. There was a positive correlation between HP infection and CD44v6 expression (P< 0.01). Both CD44v6 expression and HP infection in intestinal type gastric cancer were higher than those in diffuse type gastric cancer (P >0.05). The positive rate of HP cagA antibody in serum was higher than that of HP infection in gastric cancer tissue (P >0.05). CONCLUSION: The positive rate of CD44v6 was high in gastric cancer and may serve as a marker for diagnosing gastric cancer. There is obvious correlationship between CD44v6 expression and HP infection.

Aged↗

PubMed2002

[Effect of corticosteroids on the balance of Th cytokines in patients with systemic lupus erythematosus].

OBJECTIVE: To investigate the levels of Th cell-derived cytokines and the effect of corticosteroids on the balance of Th1/Th2 cytokines in patients with systemic lupus erythematosus (SLE). METHODS: Fifty-eight SLE patients were treated with corticosteroids. Their IFN-gamma, IL-4 and IL-10 levels were detected by ELISA before and after the treatment with corticosteroids respectively; and the SLEDAI scores of the patients were compared before and after the treatment. RESULTS: Before the treatment, the serum levels of IFN-gamma, IL-4 and IL-10 were higher than those of the healthy controls (P < 0.05). After the treatment with corticosteroids, the elevated levels of IFN-gamma, IL-4 and IL-10 in the SLE patients were all significantly reduced than those before the treatment (P < 0.05). At the same time, the SLEDAI scores were significantly lower than those before the treatment (P < 0.01). The serum level of IFN-gamma was significantly decreased in the patients with SLE compared with the healthy controls (P < 0.05). By contrast, the levels of IL-4 and IL-10 of the patients with SLE were significantly increased compared with the healthy controls (P < 0.05). CONCLUSION: Corticosteroids may induce a shift from the Th1 to Th2 profile of cytokine secretion. This may be one aspect of the mechanisms for corticosteroids treatment.

Adolescent↗

PubMed2002

Synthesis, crystal structure, and ESR study of a novel phosphorylated lipophilic spin trap.

In this article, the synthesis of a novel alpha-phosphorus-containing spin trap DEPPEPO [2-(diethoxyphosphoryl)-2-phenethyl-3,4-dihydro-2H-pyrrole-1-oxide] and the evaluation of its ability to spin-trap radicals, especially superoxide and hydroxyl radicals, are described. Single crystal X-ray structure analysis reveals that there exist a lot of intramolecular nonbonded attractive interactions in the molecule. The phenethyl group is located away from the diethoxyphosphoryl group and the nitronyl plane, and only one face of the nitronyl plane is sterically hindered by the oxygen attached to the phosphorus with a double bond. The latter feature is responsible for the stereoselection of the free radical additions on the nitronyl moiety. The ability of DEPPEPO to trap the active superoxide anion radical generated in the HX/XO system and the stability of their spin adduct were investigated with that for DEPMPO. The half-life of DEPPEPO is about 13.4 min, and as a result, the DEPPEPO seems to be a promising lipophilic spin trap, perhaps in both in vitro and in vivo ESR investigation. Because DEPPEPO is a solid compound, it is quite easy to purify by recrystallization and to store the compound even at room temperature. In addition, an obvious increase in lipophilicity for DEPPEPO was found as a contribution of 2-substituted phenethyl.

Journal Article↗

PubMed2002

Improvement of the interferometric method for measuring electro-optic coefficients of poled polymer thin films.

The interferometric method for measuring the linear electro-optic coefficients of polymer films has been improved. This improved method is based on using the antipiezoelectric effect of a quartz crystal to compensate for the change in the optical path length that is due to the electro-optic effect of a polymer film. The electro-optic coefficients of six kinds of new poled polymer film have been determined at a wavelength of 633 nm by this new method. This technique offers a simple, rapid, and highly sensitive method for measuring the electro-optic coefficients of polymer films.

Journal Article↗

PubMed2002

Requirement for the lymphocyte semaphorin, CD100, in the induction of antigen-specific T cells and the maturation of dendritic cells.

CD100 belongs to the semaphorin family, several members of which are known to act as repulsive axonal guidance factors during neuronal development. We have previously demonstrated that CD100 plays a crucial role in humoral immunity. In this study, we show that CD100 is also important for cellular immunity through the maturation of dendritic cells (DCs). CD100(-/-) mice fail to develop experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein peptide, because myelin oligodendrocyte glycoprotein-specific T cells are not generated in the absence of CD100. In vitro studies with T cells from OVA-specific TCR-transgenic mice demonstrate that Ag-specific T cells lacking CD100 fail to differentiate into cells producing either IL-4 or IFN-gamma in the presence of APCs and OVA peptide. In addition, DCs from CD100(-/-) mice display poor allostimulatory capabilities and defects in costimulatory molecule expression and IL-12 production. The addition of exogenous soluble rCD100 restores normal functions in CD100(-/-) DCs and further enhances functions of normal DCs. Furthermore, treatment of Ag-pulsed DCs with both soluble CD100 and anti-CD40 before immunization significantly enhances their immunogenicity. This treatment elicits improved T cell priming in vivo, enhancing both primary and memory T cell responses. Collectively, these results demonstrate that CD100, which enhances the maturation of DCs, is essential in the activation and differentiation of Ag-specific T cells.

Animals↗