Biomedical subjects
Publications and source records attributed to Ying Zhang.
CuS-poly(N-isopropylacrylamide), CuS-poly(N-isopropylacrylamide-co-methacrylic acid), Ag(2)S-poly(N-isopropylacrylamide) and Ag(2)S-poly(N-isopropylacrylamide-co-methacrylic acid) composite microspheres exhibiting complex surface morphologies were prepared by employing the minigel template method.
Signal transducers and activators of transcription (STATs) are latent cytoplasmic transcription factors that are activated and translocated into the nucleus after phosphorylation at a conserved tyrosine residue. Mouse model studies have demonstrated that activated Stat5a acts as a critical survival factor for normal, preneoplastic and malignant mammary epithelial cells. Very limited information is available, however, on the expression, tyrosine phosphorylation status and nuclear localization of Stat5a in human breast cancers. In our study, the pattern of Stat5a cellular localization was analyzed by immunohistochemistry in a series of 83 randomly selected primary human breast adenocarcinomas. Immunoprecipitation/Western blotting and immunohistochemistry assays employing different phospho-specific antibodies verified Stat5a tyrosine phosphorylation status. Stat5a was nuclear localized and tyrosine phosphorylated in 59 of 78 (76%) breast cancers examined; 38 of 78 (49%) demonstrated Stat5a nuclear localization in more than 25% of the breast cancer cells within the adenocarcinomas. Nuclear localized Stat5a was associated positively with increased levels of histologic differentiation (p = 0.03). A statistically significant positive association with p27 nuclear localization also was identified (p = 0.05). No relationship was found between nuclear localized Stat5a and menopausal status, tumor size, ploidy, percentage of cells in S-phase, lymph node metastases, ER, ErbB2, nuclear localized p21 or nuclear localized Stat5b/Stat3. As its role in human breast cancer progression and response to therapy is defined, Stat5a could become a new molecular target for breast cancer therapy.
Binding constants of the glycopeptide antibiotics teicoplanin (Teic), ristocetin (Rist), and vancomycin (Van), and their derivatives to D-Ala-D-Ala terminus peptides were determined by on-column ligand and receptor synthesis coupled to affinity capillary electrophoresis (ACE) or partial filling ACE (PFACE). In the first technique, 9-fluorenylmethoxycarbonyl (Fmoc)-amino acid-D-Ala-D-Ala species are first synthesized using on-column techniques. The initial sample plug contains a D-Ala-D-Ala terminus peptide and two non-interacting standards. Plugs two and three contain solutions of Fmoc-amino acid-N-hydroxysuccinimide (NHS) ester and buffer, respectively. Upon electrophoresis, the initial D-Ala-D-Ala peptide reacts with the Fmoc-amino acid NHS ester yielding the Fmoc-amino acid D-Ala-D-Ala peptide. Continued electrophoresis results in the overlap of the glycopeptide in the running buffer and the plug of Fmoc-amino acid-D-Ala-D-Ala peptide and non-interacting markers. Subsequent analysis of the change in the electrophoretic mobility (mu) or relative migration time ratio (RMTR) of the peptide relative to the non-interacting standards, as a function of the concentration of the antibiotic, yields a value for the binding constant. In the second technique, derivatives of the glycopeptides Teic and Rist are first synthesized on-column before analysis by ACE or PFACE. After the column has been partially filled with increasing concentrations of D-Ala-D-Ala terminus peptides, a plug of buffer followed by two separate plugs of reagents are injected. The order of the reagent plugs containing the antibiotic and two non-interacting standards and the anhydride varies with the charge of the glycopeptide. Upon electrophoresis, the antibiotic reacts with the anhydride yielding a derivative of Teic or Rist. Continued electrophoresis results in the overlap of the derivatized antibiotic and the plug of D-Ala-D-Ala peptide. Analysis of the change in RMTR of the new glycopeptide relative to the non-interacting standards, as a function of the concentration of the D-Ala-D-Ala ligand yields a value for the binding constant.
OBJECTIVE: To determine the effect of raloxifene hydrochloride (RLX) on the lumbar spine and total hip bone mineral density (BMD), bone metabolism and serum lipids in Chinese postmenopausal women with osteoporosis. METHODS: 204 Chinese postmenopausal women with osteoporosis from 3 hospitals in Beijing and Shanghai were randomly divided into 2 groups of 102 women: RLX group (RLX of the dosage of 60 mg/day was given for 12 months) and placebo group. In addition, 500 mg of elemental calcium and 200 units of vitamin D were given daily to all women. BMD, serum bone markers and lipids were measured before and after drug administration. The BMD of lumber spine and hip was measured by dual-energy X-ray absorptiometry (DEXA). Serum bone gamma-carboxyglutamic acid-containing protein (BGP) and C-teloppeptide were analyzed by one-step ELISA. Serum lipids were measured by enzymatic method. RESULTS: By the end of the 12-month study period, the lumbar spine BMD was increased by 3.3% +/- 4.8% in the RLX group and 1.0% +/- 4.9% in the placebo group (P < 0.001); the hip BMD was increased by 1.4% +/- 4.8%in the RLX group and decreased by 0.9% +/- 5.0% in the placebo group (P < 0.01). New vertebral fracture occurred in none of the subjects in the RLX group and in 5 subjects of the placebo group (P = 0.059). The serum BGP and CTX decreased by 41.7% and 61.5% respectively in the RLX group, both significantly more than those in the placebo group (10.6% and 35.6% respectively, both P < 0.001). Both the total cholesterol and low-density lipoprotein cholesterol were significantly lower in the RLX group than in the placebo group (both P < 0.001), however, there were no significant differences in high-density lipoprotein cholesterol and triglycerides between these two groups. One subject in the RLX group and 5 subjects in the placebo group discontinued the study due to adverse events. There were no differences in the number of subjects with hot flushes (3 in the RLX group and 1 in the placebo group) and the number of subjects with leg cramps (9 in the RLX group and 4 in the placebo group). No venous thromboembolic event was reported. CONCLUSION: RLX of the dosage of 60 mg/day for 12 months significantly increases the lumbar spine and total hip bone BMD, significantly decreases bone turnover and has favorable effects on serum lipids in Chinese postmenopausal women with osteoporosis.
The dependence of second-harmonic-generation (SHG) conversion efficiency on the intercrystal phase shift between two nonlinear crystals is analyzed with heuristic theory, and a novel scheme for SHG with two cascaded nonlinear crystals and a polarization modulator is proposed. More than 30 W output power is obtained experimentally at 532 nm with 70% external doubling efficiency. To the best of our knowledge, this is the highest conversion efficiency obtained with LiB3O5 crystal external frequency doubling. This scheme provides a simple and effective method for improving second-harmonic conversion efficiency.
Previous work from our laboratory indicated that female Wistar rats will self-administer ethanol (EtOH) directly into the posterior ventral tegmental area (VTA). These results suggested that VTA dopamine (DA) neurons might be involved in mediating the reinforcing actions of EtOH within this region. The objectives of this study were to determine (1) the dose-response effects for the self-administration of EtOH into the VTA of male Wistar rats, and (2) the involvement of VTA DA neurons in the reinforcing actions of EtOH within the VTA. Adult male Wistar rats were implanted stereotaxically with guide cannulas aimed at the posterior or anterior VTA. After 1 week, rats were placed in standard two-lever (active and inactive) experimental chambers for a total of seven to eight sessions. The first experiment determined the intracranial self-administration of EtOH (0-400 mg%) into the posterior and anterior VTA. The second experiment examined the effects of coadministration of the D2/3 agonist quinpirole on the acquisition and maintenance of EtOH self-infusions into the posterior VTA. The final experiment determined the effects of a D2 antagonist (sulpiride) to reinstate self-administration behavior in rats given EtOH and quinpirole to coadminister. Male Wistar rats self-infused 100-300 mg% EtOH directly into the posterior, but not anterior, VTA. Coadministration of quinpirole prevented the acquisition and extinguished the maintenance of EtOH self-infusion into the posterior VTA, and addition of sulpiride reinstated EtOH self-administration. The results of this study indicate that EtOH is reinforcing within the posterior VTA of male Wistar rats and suggest that activation of VTA DA neurons is involved in this process.
OBJECTIVE: Novel anti-mesangial cell antibodies have been identified in sera of majority patients with lupus nephritis in our previous study. The aims of current study were to investigate the association of anti-mesangial cell antibodies and anti-DNA antibodies, and whether the target antigens were on mesangial cell membrane. METHODS: Affinity parified anti-DNA antibodies and sera with depletion of anti-DNA antibodies from three patients with lupus nephritis were used in Western-blot analysis to identify antigens in culture human glomerular mesangial cell line. Cell membrane from in vitro cultured human mesagial cell line was separated by gradient centrifugation technique, and the target antigens were identified by Western-blot analysis using 1% Triton X-100 solublized membrane protein as antigens and four known anti-mesangial cell antibody positive sera from patients with lupus nephritis as probes. RESULTS: Soluble proteins from in vitro cultured human mesangial cells could be blotted by both affinity purified anti-DNA antibodies (molecular weight at 63,000, 91,000 and 125,000) and sera with depletion of anti-DNA antibodies (molecular weight at 74,000 and 36,000). Proteins with molecular weight at 101,000, 91,000, 74,000 and 31,000 in mesangial cell membrane could be blotted by the four known anti-mesangial cell antibody positive sera. CONCLUSION: Some anti-mesangial cell antibodies were not associated with anti-DNA antibodies and anti-mesiangial cell antibodies could direct interact with antigens located on mesangial cell membrane. Anti-mesangial cell antibodies may play an important role in the pathogenesis of lupus nephritis.
Megakaryocytes skip late anaphase and cytokinesis during endomitosis. We found normal expression and localization of a fundamental regulator of mitosis, Aurora-B/AIM-1, during prophase in polyploidizing mouse bone marrow megakaryocytes. At late anaphase, however, Aurora-B/AIM-1 is absent or mislocalized. Megakaryocytes treated with a proteasome inhibitor display Aurora-B/AIM-1 properly expressed and localized to the midzone, suggesting that protein degradation contributes to this atypical appearance. In contrast, survivin, an Aurora-B/AIM-1 coregulator of mitosis, is not detected at any stage of the endomitotic cell cycle, and in most megakaryocytes proteasome inhibition does not rescue this phenotype. To further explore the importance of reduced Aurora-B/AIM-1 for polyploidization, it was overexpressed in megakaryocytes of transgenic mice. The phenotype includes increased transgenic mRNA, but not protein, in polyploidy megakaryocytes, further suggesting that Aurora-B/AIM-1 is regulated at the protein level. Aurora-B/AIM-1 protein is, however, elevated in diploid transgenic megakaryocytes. Transgenic mice also exhibit enhanced numbers of megakaryocytes with increased proliferative potential, and some mice exhibit mild decreases in ploidy level. Hence, the molecular programming involved in endomitosis is characterized by the mislocalization or absence of at least 2 critical mitotic regulators, Aurora-B/AIM-1 and survivin. Future studies will examine the impact of survivin restoration on mouse megakaryocyte polyploidization.
Ischemic acute renal failure involves not only the kidney but also extrarenal organs such as the bone marrow that produces inflammatory cells. By ELISA and RNase protection assays, we now show that renal ischemia-reperfusion increases serum concentrations of granulocyte macrophage colony-stimulating factor (G-CSF) protein and increases both G-CSF mRNA and protein in the ischemic kidney. In situ hybridization localized the increased G-CSF mRNA to tubule cells, including medullary thick ascending limb cells (mTAL), in the outer medulla. We also show that mTAL produce G-CSF protein and increase G-CSF mRNA after stimulation by reactive oxygen species in vitro. The production of G-CSF by the kidney after ischemia-reperfusion provides a means of communication from the injured kidney to the bone marrow. This supports the known inflammatory response to ischemia.
BACKGROUND: Mannose-binding lectin (MBL) is a circulating immune factor responsible for opsonization of pathogens and directly activating complement. Common variations in the MBL gene are responsible for an opsonic deficiency that affects 5% to 7% of whites and are associated with increased susceptibility to infections. After a preliminary report associating these variations with coronary artery disease (CAD), we determined MBL genotypes in 3 American Indian communities experiencing an increased mortality and morbidity from CAD. METHODS AND RESULTS: We examined DNA from 434 participants in a population-based cohort, the Strong Heart Study. Genotypes for 3 common MBL coding variations and 1 promoter polymorphism were determined. The frequency of a composite genotype that conferred low MBL levels was 20.7% in 217 cases and 11.1% in matched controls without CAD. A conditional logistic regression model indicated a univariate OR for CAD of 2.3 (95% CI 1.3 to 4.2, P=0.005) for the variant genotypes. After adjustment for demographic and CAD risk factors, including type 2 diabetes mellitus, fibrinogen, triglycerides, and hypertension, the OR was 3.2 (95% CI 1.5 to 7.0, P=0.004). CONCLUSIONS: Variant MBL genotypes coding for markedly diminished levels of MBL are predictive of CAD. After adjustment for multiple traditional risk factors for ischemic heart disease, this association remains significant. A high prevalence of variant MBL alleles and CAD in this population suggests that potentially important public health benefits may accrue from future interventions based on these genotypes.
OBJECTIVE: To explore a better method to establish an animal model of temporal epilepsy in rat and study the pathological basis of permanent epilepsy sensitivity. METHODS: Kainic acid (KA) with the dosage calculated according to the body weight was injected into 30 Wistar rats' hippocampuses by stereotactic operation. Videotape recording was used to record the seizures for 8 weeks. Two rats were randomly selected to undergo craniotomy and electroencephalography and then were killed to have their brains to be taken out to undergo slicing, staining, and histological examination 6 hours, 1 days, 3 days, 5 days, 7 days, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, and 8 weeks respectively after operation. RESULTS: Thirty minutes after the rats awoke from anesthesia, wet-dog shakes, lips and head self-movements, convulsion of forelimbs and hind limbs occurred successively. The seizures were paroxysmal with increased intervals during which, however, the rats still showed sluggish. Twenty-four hours after the rats' behavior recovered to normal. Then the seizure occurred 1 approximately 3 times every week. Epileptic waves were recorded in the hippocampus, striate body, cerebral cortex, and olfactory bulb from 5 hours to 2 months after the establishment of model. CONCLUSION: The seizure pattern and pathological basis of temporal epilepsy in the rat model established by stereotactic management were almost the same as those in human beings. Stereotactic method significantly decreased the needed dosage of KA and the cost in comparison with systematic injection. Loss of hippocampus neurons and hyperplasia of gliocytes are the basis of the permanent epilepsy sensitivity in the animal model.
BACKGROUND: Pyrazinamide is a paradoxical frontline tuberculosis drug characterized by high in vivo sterilizing activity but poor in vitro activity. This separation in pyrazinamide activity reflects differences between the in vivo tissue environment and in vitro culture conditions. The well-known acid pH requirement for pyrazinamide activity was discovered previously based on such reasoning but does not completely explain the discrepancy between in vivo and in vitro activity of pyrazinamide. This study examined the effect of iron, which could potentially be elevated in local inflammatory lesions, on pyrazinamide activity in vitro. MATERIALS AND METHODS: The effect of iron on the activity of pyrazinamide or its active derivative pyrazinoic acid against Mycobacterium tuberculosis was assessed in liquid medium in a drug exposure assay or in solid medium with pyrazinamide plus iron or pyrazinamide alone. The effect of iron on pyrazinamide or pyrazinoic acid was expressed as percentage of growth inhibition. RESULTS: We have shown that iron enhances the activity of pyrazinamide and pyrazinoic acid against M. tuberculosis in both liquid and solid media at acid pH 5.6. Iron enhanced the activity of pyrazinoic acid but not pyrazinamide against the naturally pyrazinamide-resistant Mycobacterium bovis BCG. Other metal ions such as magnesium, calcium and zinc did not enhance the activity of pyrazinamide or pyrazinoic acid. CONCLUSIONS: Iron increased the activity of pyrazinamide or pyrazinoic acid against M. tuberculosis in vitro. These findings may have implications for the study of mechanism of action of pyrazinamide and possible iron supplement for improving the activity of pyrazinamide.
BACKGROUND: Radical prostatectomy is used widely for the treatment of patients with localized prostate carcinoma. No long-term analysis has been reported on a series of radical prostatectomies performed in a community-based health maintenance organization. METHODS: Charts and histologic slides were reviewed from 750 patients who underwent radical prostatectomy between 1970 and 1996 at a community-based health maintenance organization. The influences of a number of variables were analyzed for their impact on progression free survival (PFS) and overall survival (OS). RESULTS: With a median follow-up of 6.2 years among survivors, 137 patients (18%) had progressive disease, and 149 patients (20%) died from all causes. The median OS from the date of diagnosis was 15.7 years (95% confidence interval, 13.6-17.2), similar to the expected median survival of 16.2 years. The median PFS from diagnosis was not reached, but 75% of patients were progression free > or = 10.6 years after undergoing prostatectomy. The prognostic factors included Gleason score, age at diagnosis, and T stage. Outcomes were comparable with reports of surgical series from university-based practices. CONCLUSIONS: The patient characteristics that had important, favorable correlation with survival included Gleason score < or = 6, T1 or T2 tumor status, and younger age at diagnosis. Lower prostate-specific antigen values at diagnosis, together with the former two parameters, also had a favorable correlation with PFS. Radical prostatectomy in a community-based health maintenance organization was followed by long-term PFS and OS comparable to outcomes reported from university-based practices. The impact of radical prostatectomy on survival remains to be demonstrated.
CMV423 (2-chloro-3-pyridin-3-yl-5,6,7,8-tetrahydroindolizine-1-carboxamide) is a new antiviral agent with potent and selective in vitro activity against the beta-herpesvirus human cytomegalovirus (HCMV), but not against alpha- or gamma-herpesviruses. Here we report that its activity also extends to human herpesvirus 6 (HHV-6) and 7 (HHV-7). When compared in vitro to ganciclovir and foscarnet (the standard drugs recommended for treatment of HHV-6 infections), CMV423 showed a superior selectivity, due to its high activity (antiviral IC(50): 53nM) and low cytotoxicity (CC(50): 144microM), both in continuous cell lines and in CBLCs infected with HHV-6. From mechanistic experiments at the level of viral mRNA and protein expression, we learned that CMV423 targets an event following viral entry but preceding viral DNA replication. Its antiviral action was dependent on the cell line used, implying involvement of a cellular component. When compared to a panel of known protein kinase inhibitors, CMV423 was found to share anti-HHV-6 characteristics with herbimycin A, which affects tyrosine kinase activity through heat shock protein 90 (Hsp90) inhibition. We demonstrated that high concentrations of CMV423 have an inhibitory effect on the total cellular protein tyrosine kinase activity, and that CMV423 and herbimycin A, when combined, act synergistically against HHV-6. The activities of cyclin-dependent kinases, protein kinases A and C, and the HHV-6-encoded pU69 kinase were not affected. We, therefore, conclude that CMV423 exerts its activity against HHV-6 through inhibition of a cellular process that is critical at early stages of viral replication and that may affect protein tyrosine kinase activity.
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OBJECTIVE: To construct the gene co-expression vector of immunoglobulin heavy chain variable region (IgHV) gene and GM-CSF or IL-2 as IgHV family specific nucleic acid vaccine to lymphoma, and study the immune response of the immunized mice against lymphoma. METHODS: Six clones with significantly different length in gene fragments were selected from a gene bank constructed from normal fetal umbilical cord blood. These gene fragments in the clones were sequenced. The sequences were translated into IgHV peptides. T cell epitopes in the IgHV were predicted by bioinformatics. Meanwhile 6 clones of IgHV1 constructed before were analyzed. The most typical clone of IgHV1 and IgHV3 containing most of the T cell epitopes were selected. The IgHV gene fragments whose complementary determining region 3 (CDR3) was cut out and composed mainly of framework region were cloned into eukaryotic expression vector. The gene fragments of framework region of IgHV linking with gene of GM-CSF or IL-2 were cloned into pcDNA3.0 to form fusion genes of IgHV (FR)-GM-CSF/IL-2. Then they were transected into COS cells, African green monkey renal cells, by Lipofectin and their transient expression product was detected by ELISA. Twenty male Balb/c mice were randomly divided into 5 groups of 4 mice to be injected with different vectors at the weeks 0, 2, and 4: with IgHV3 (FR)/pcDNA3.0, with IgHV3 (FR)-IL-2/pcDNA 3.0, with blank vector pcDNA3.0 as control, with IgHV1 (FR)/pcDNA3.0, and with IgHV1 (FR)-IL-2/pcDNA3.0. At the weeks 0, 2, 4, 6, and 8 serum was collected from the mice to undergo indirect immunofluorescence examination to detect the antibodies against Namalwa cells, lymphoma cells from Africa green monkey, and normal lymphocytes. ELISA was used to examine the serum interferon (IFN)-gamma. RESULTS: About 30 of T cell epitopes existed in each IgHV peptides predicted by bioinformatics. Among the bioinformatics prediction, about 90% of the T cell epitopes were in the framework region (FR) of IgHV, and the first 10% with higher prediction score were in FR. The CDR3 of two typical IgHV sequences were cut down and the remaining sequences, mainly composed of FR, were used to construct the IgHV (FR)/pcDNA3.0 expression vectors. The 3' end of IgHV1 (FR) and IgHV3 (FR) were linked to GM-CSF or IL-2 gene successfully. The expression of GM-CSF in the group transfected with IgHV (FR)-GM-CSF/pcDNA3.0 were 200 times higher than in the group transfected with control pcDNA3.0. The expression of IL-2 in the group transfected with IgHV (FR)-IL-2/pcDNA3.0 were 60 times higher than in the group transfected with control pcDNA3.0. The antibody against IgHV1 family lymphoma cell line Namalwa could be detected since the second week in the mice immunized with IgHV1 (FR)-IL-2/pcDNA3.0. The antibody could be detected since the fourth week in the mice immunized with IgHV1 (FR). The antibody against lymphocyte line of IgHV3 family could be detected since the second week in the mice immunized with IgHV3 (FR)-IL-2/pcDNA3.0. The antibody could be detected since the fourth week in the mice immunized with IgHV3 (FR)/pcDNA3.0. The contents of serum IFN-gamma the mice immunized with IgHV1 (FR)-IL-2/pcDNA3.0 and with IgHV3 (FR)-IL-2/pcDNA3.0 was significantly higher than those of the mice immunized with IgHV (FR)/pcDNA3.0 or pcDNA3.0 (all P < 0.01). CONCLUSION: The gene fragments of IgHV (FR) can be used to construct IgHV family specific nucleic acid vaccine that induces anti-lymphoma immune response in mice by muscle injection. The expressing vectors of IgHV (FR)-GM-CSF/IL-2 induces stronger immunoreaction.
Tuberculosis is a worldwide health problem posing increasing threat with the spread of HIV infection and drug resistant Mycobacterium tuberculosis strains. Consequently, control of this disease has become a significant challenge despite the availability of chemotherapy and BCG vaccine. Drug resistance for all first-line anti-tuberculosis agents and some second-line agents has been observed. Moreover, the occurrence of strains of M. tuberculosis resistant to multiple anti-tuberculosis drugs is increasing. Mechanisms of action and resistance of major anti-tuberculosis drugs are reviewed. In addition, the phenotypic drug resistance such as dormant or persistent tubercle bacilli and its importance are also emphasized. In order to combat the threat of drug resistant tuberculosis and to more effectively control the disease, an understanding of the mechanisms underlying drug resistance is necessary. This knowledge could be used for the development of molecular tests for rapid detection of drug resistant bacilli and future anti-tuberculosis drugs.
An experimental model of rhegmatogenous retinal detachment (RRD) in rabbits was established to simulate the pathophysiologic condition of human RRD. 24 rabbits were randomly divided into 3 groups and underwent vitrectomy with a vitrector and/or retinotomy with a Charles flute needle, with 12 in group I (vitrectomy and retinotomy), 7 in group I (retinotomy) and 5 in group III (vitrectomy). All animals underwent follow-up examinations with direct and indirect ophthalmoscopy and fundus photography 12 h and day 1, 3, 5, 7, 10, 14, 21, and 28 after the procedure(s). Retinal changes were recorded. As a result, 10 RRDs were successfully established in group I. Direct and indirect ophthalmoscopy and fundus photography demonstrated typical features of RRD. No RRD developed in group II and III. It was concluded that the experimental rhegmatogenous retinal detachment produced in a rabbit model after vitrectomy with retinotomy in this study was a convenient and reliable one. This RRD model mimicked the typical pathophysiological changes in humans.