Biomedical subjects

Ying Zhang

Publications and source records attributed to Ying Zhang.

At least 217 records · Page 12Linked to original sources

PubMed2005

Competitive hybridization kinetics reveals unexpected behavior patterns.

Although the kinetics of hybridization between a soluble polynucleotide and an immobilized complementary sequence have been studied by others, it is almost universally assumed that the interaction between each probe/target pair can be treated as a separate event. This simplifies the mathematics considerably, but it can give a false picture of the extent of hybridization that one achieves at equilibrium as well as the relative quantities of each hybridized pair during the approach to equilibrium. Here we solve the relevant kinetics equations simultaneously using Mathematica as a simulation language. Among the interesting results of this study are that, for certain circumstances, the relative ratio of incorrect to correct hybrids can change dramatically with time; that the relative abundances of two pairs are not what one would expect based on their equilibrium dissociation constants; that the volume of a wash solution after hybridization can have a large effect on results; and the fact that a short wash is typically better than a long one. We show that an optimum wash time exists for a given set of conditions. In addition, the ratio of soluble to insoluble (spotted) molecules can influence results substantially. Finally, the true levels of rare transcripts can be masked by the presence of highly abundant ones. Code is supplied to enable others to study conditions beyond those presented in this article.

Base Composition↗

PubMed2005

Anion chelation-induced porphyrin protonation and its application for chloride anion sensing.

The protonation of a simple meso-tetraphenylporphyrin in an organic-aqueous system was found to be induced by the counteranions. During the process of protonation, the counteranion of the proton sources binds with the porphyrin core and thus promotes the complexation of the porphyrin and protons. The interaction of porphyrin and anion was characterized by fluorescence, UV-visible, cyclic voltammetry, (1)H NMR, and IR. Moreover, it could be exploited in selective fluorescent sensing of Cl(-). The sensing mechanism was based on extraction of protons from the aqueous phase into the organic phase by free base porphyrin and simultaneous coextraction of Cl(-), which promoted porphyrin protonation, and hence resulted in significant changes of the porphyrin fluorescence spectra. Selectivity trends turned out to be dependent upon the lipophilicity of anion and the binding affinity and structure complementarity between the protonated porphyrin and anions. The fluorescence enhancement of the porphyrin band at 684 nm showed modest selectivity for Cl(-) and NO(3)(-).

Anions↗

PubMed2005

DNA electroporation prime and protein boost strategy enhances humoral immunity of tuberculosis DNA vaccines in mice and non-human primates.

DNA vaccines have shown to induce strong immune response in small animals; however, its capacity of inducing robust antigen-specific immune responses in large animals is limited. In the present study, in vivo electroporation (EP) was applied and the effect of EP on humoral immune response against tuberculosis (TB) induced by DNA vaccination was tested in mice and rhesus macaques. Mice injected with 10 microg DNA encoding Ag85A and ESAT-6 followed by EP showed a reproducible humoral immunity which was equal to that obtained by using 100 microg DNA without EP. Boosting the DNA/EP treated animals with corresponding recombinant protein (50 microg of either Ag85A or ESAT-6) without adding adjuvant gave more than a 7-8-fold increase in the antibody titre but only 3-4-fold increase was found in the mice receiving 100 microg DNA without EP followed by protein boost. In concordance with the results obtained in mice, the monkeys received less DNA achieved equal high antibody responses to those induced by high dosage of DNA. Boosting the the DNA/EP treated monkeys with TB protein (500 microg of either Ag85A or ESAT-6) improved the humoral response by 7-8-fold increase in antibody titre, indicating electroporation's ability to compensate lower DNA concentration and enhance humoral immunity of TB DNA vaccines in mice and non-human primates.

Animals↗

PubMed2005

C-reactive protein as a predictor of cardiovascular risk in a population with a high prevalence of diabetes: the Strong Heart Study.

BACKGROUND: High-sensitivity C-reactive protein (CRP) has been investigated extensively as a marker for predicting the risk of cardiovascular disease (CVD). CVD accounts for a large proportion of mortality and morbidity in American Indians; we sought to test the association of CRP and CVD in a population-based American Indian cohort 45 to 74 years old. METHODS AND RESULTS: Of 3277 participants who were CVD-free at baseline, 542 had CRP >10 mg/L and were excluded from analysis; 50.1% of those included had diabetes. There were 343 CVD events among this cohort during a median follow-up of 6.2 years. Multiple CVD risk factors were used as covariates in Cox proportional-hazard models. After exclusions, the median CRP (3.2 mg/L) was higher than reported in many other populations. CRP predicted CVD in models adjusted for traditional risk factors, but not when albuminuria and fibrinogen were included. In subgroup analysis, CRP was strongly related to incident CVD among nondiabetic women participants, even after adjustment for traditional CVD risk factors and other indicators of inflammation. Conversely, CRP was elevated beyond the useful range of the American Heart Association/Centers for Disease Control and Prevention clinical guidelines in 16% of this population, and CRP was not predictive of CVD in important subgroups, such as those with diabetes. CONCLUSIONS: CRP was a predictor of CVD in this American Indian population with a high prevalence of diabetes and other risk factors. The predictive ability of CRP varies considerably among subgroups with different risk factor profiles.

Aged↗

PubMed2005

[Anti-endothelial cell antibodies(AECA) are associated with disease activity of propylthiouracil induced antineutrophil cytoplasmic antibody (ANCA) positive vasculitis].

OBJECTIVE: To investigate the prevalence of anti-endothelial cell antibodies(AECA) and its possible role in the pathogenesis of propylthiouracil (PTU) induced ANCA positive vasculitis. METHODS: Sera from 11 patients with PTU induced ANCA positive vasculitis and 10 patients with PTU induced ANCA but without clinical vasculitis were studied. Soluble proteins from in vitro cultured human umbilical vein endothelial cells were used as antigens and immunoblotting technique was performed to identify the specific target antigens. RESULTS: In patients with PTU induced ANCA positive vasculitis group, 10 of the 11 patients in active phase were AECA positive and 7 of the 10 patients turned to negative in remission. AECA consisted of a group of heterogeneous antibodies. In patients with ANCA positive but without vasculitis, none was AECA positive. CONCLUSION: AECAs recognizing a variety of antigens could be found in sera from patients with PTU induced ANCA positive vasculitis and they had a much closer association with vasculitic disease activity compared with ANCA.

Adolescent↗

PubMed2005

Activation of signal transducer and activator of transcription-5 in prostate cancer predicts early recurrence.

PURPOSE: We have shown previously that the signal transducer and activator of transcription-5 (Stat5) is a critical survival factor in human prostate cancer cells. In addition, we recently showed that Stat5 is activated at a high level, particularly in high-grade human prostate cancers. Here, we investigated whether activation of Stat5 in prostate cancer was linked to clinical outcome with disease recurrence as end point. EXPERIMENTAL DESIGN: Immunohistochemistry was used to detect active, nuclear Stat5 in 357 paraffin-embedded prostate cancer specimens on a tissue microarray with clinical follow-up data. Stat5 activation status in prostate cancer specimens was analyzed by univariate and multivariate survival analysis to determine whether activation of Stat5 predicts earlier prostate cancer recurrence. Separate sets of statistical analysis were done for all patients regardless of Gleason grade and for patients with prostate cancer of intermediate Gleason grades (3 and 4). RESULTS AND CONCLUSIONS: Stat5 activation in prostate cancer was associated with early disease recurrence (P = 0.0399). Importantly, active Stat5 also predicted shorter progression-free survival in intermediate Gleason grade prostate cancers (P = 0.0409). Stat5 activation remained an independent prognostic marker after adjusting for Gleason grade, pT stage, perineural invasion, or seminal vesicle infiltration in all patients (P = 0.0565) and in Gleason grade 3 or 4 patients (P = 0.0582). The results of this work also confirmed our previous finding of association of Stat5 activation with a high histologic grade of prostate cancer (R = 0.11, P = 0.033). In summary, our study shows that active Stat5 distinguished prostate cancer patients whose disease is likely to progress earlier; therefore, active Stat5 may be a useful marker for selection of more individualized treatment. The results of this study need to be validated in a large prospective cohort.

Aged↗

PubMed2005

Crystallization and preliminary crystallographic studies of the recombinant antitumour lectin from the edible mushroom Agrocybe aegerita.

The antitumour lectin from Agrocybe aegerita, named AAL, shows strong inhibition effects on human and mouse tumour cells via apoptosis induction activity. Recombinant AAL (rAAL) has been expressed and purified. Both rAAL and rAAL-lactose complex have been crystallized and their X-ray diffraction data were collected to resolutions of 1.9 A and 1.6 A, respectively. Both crystals belong to space group P2(1) with unit cell parameters a = 53.20 A, b = 66.01 A, c = 57.86 A, beta = 109.38 and a = 53.38 A, b = 66.29 A, c = 58.02 A, beta = 109.03, respectively.

Agaricales↗

PubMed2005

Calmodulin interaction with peptides from G-protein coupled receptors measured with S-Tag labeling.

We have developed a quantitative assay of calmodulin (CaM) binding to S-Tag labeled peptides derived from G-protein coupled receptor (GPCR) sequences. CaM binding of peptides derived from the third intracellular loop (i3) of mu opioid receptor (MOR) was confirmed and the CaM-binding motif refined. A MORi3 peptide with a Lys > Ala substitution--shown to reduce CaM-binding of intact MOR--bound fivefold less avidly than the wild-type peptide. Screening peptides derived from i3 loops of other GPCR families confirmed 5HT1A, and identified muscarinic receptor 3, and melanocortin receptor 1, as proteins carrying CaM-binding domains. The use of S-Tag labeling can serve for rapid screening of putative CaM-binding domains in GPCRs.

Binding Sites↗

PubMed2005

Activity-independent coregulation of IA and Ih in rhythmically active neurons.

The fast transient potassium or A current (IA) plays an important role in determining the activity of central pattern generator neurons. We have previously shown that the shal K+ channel gene encodes IA in neurons of the pyloric network in the spiny lobster. To further study how IA shapes pyloric neuron and network activity, we microinjected RNA for a shal-GFP fusion protein into four identified pyloric neuron types. Neurons expressing shal-GFP had a constant increase in IA amplitude, regardless of cell type. This increase in IA was paralleled by a concomitant increase in the hyperpolarization-activated cation current Ih in all pyloric neurons. Despite significant increases in these currents, only modest changes in cell firing properties were observed. We used models to test two hypotheses to explain this failure to change firing properties. First, this may reflect the mislocalization of the expressed shal protein solely to the somata and initial neurites of injected neurons, rendering it electrically remote from the integrating region in the neuropil. To test this hypothesis, we generated a multicompartment model where increases in IA could be localized to the soma, initial neurite, or neuropil/axon compartments. Although spike activity was somewhat more sensitive to increases in neuropil/axon versus somatic/primary neurite IA, increases in IA limited to the soma and primary neurite still evoked much more dramatic changes than were seen in the shal-GFP-injected neurons. Second, the effect of the increased IA could be compensated by the endogenous increase in Ih. To test this, we modeled the compensatory increases of IA and Ih with a cycling two-cell model. We found that the increase in Ih was sufficient to compensate the effects of increased IA, provided that they increase in a constant ratio, as we observed experimentally in both shal-injected and noninjected neurons. Thus an activity-independent homeostatic mechanism maintains constant neuronal activity in the face of dramatic increases in IA.

Action Potentials↗

PubMed2005

Allelic expression imbalance of human mu opioid receptor (OPRM1) caused by variant A118G.

As a primary target for opioid drugs and peptides, the mu opioid receptor (OPRM1) plays a key role in pain perception and addiction. Genetic variants of OPRM1 have been implicated in predisposition to drug addiction, in particular the single nucleotide polymorphism A118G, leading to an N40D substitution, with an allele frequency of 10-32%, and uncertain functions. We have measured allele-specific mRNA expression of OPRM1 in human autopsy brain tissues, using A118G as a marker. In 8 heterozygous samples measured, the A118 mRNA allele was 1.5-2.5-fold more abundant than the G118 allele. Transfection into Chinese hamster ovary cells of a cDNA representing only the coding region of OPRM1, carrying adenosine, guanosine, cytidine, and thymidine in position 118, resulted in 1.5-fold lower mRNA levels only for OPRM1-G118, and more than 10-fold lower OPRM1 protein levels, measured by Western blotting and receptor binding assay. After transfection and inhibition of transcription with actinomycin D, analysis of mRNA turnover failed to reveal differences in mRNA stability between A118 and G118 alleles, indicating a defect in transcription or mRNA maturation. These results indicate that OPRM1-G118 is a functional variant with deleterious effects on both mRNA and protein yield. Clarifying the functional relevance of polymorphisms associated with susceptibility to a complex disorder such as drug addiction provides a foundation for clinical association studies.

Alleles↗

PubMed2005

Premature death associated with delirium at 1-year follow-up.

BACKGROUND: While previous studies have demonstrated the increased mortality risk associated with delirium, little is known about the mortality time course. The objective of this study is to estimate the fraction of a year of life lost associated with delirium at 1-year follow-up. METHODS: Hospitalized patients 70 years and older who participated in a previous controlled clinical trial of a delirium prevention intervention at an academic medical center from March 25, 1995, through March 18, 1998, were followed up for 1 year after discharge, and patients who died were identified, along with the date of death. The adjusted number of days survived were estimated using a 2-step regression model approach and compared across patients who developed delirium during hospitalization and those who did not develop delirium. RESULTS: After adjusting for pertinent covariates (age, sex, functional status, and comorbidity), patients with delirium survived 274 days, compared with 321 days for patients without delirium, representing a difference of 13% of a year (hazard ratio, 1.62; P<.001). Results were confirmed with a separate binomial regression analysis. CONCLUSIONS: Patients who experienced delirium during hospitalization had a 62% increased risk of mortality and lost an average of 13% of a year of life compared with patients without delirium. Although delirium is an acute condition, it is associated with multiple long-term sequelae that extend beyond the hospital setting, including premature mortality.

Aged↗

PubMed2005

A novel microgel and associated post-fabrication encapsulation technique of proteins.

A novel negatively thermo-sensitive and biodegradable microgel was prepared by combination of macromer synthesis and inverse suspension polymerization. A new post-fabrication encapsulation technique based upon this kind of intelligent microgel was developed. Model proteins (hemoglobin, bovine serum albumin and insulin) were encapsulated into the microgels at 4 degrees C and released in vitro at 37 degrees C. Relatively high loading levels and sustained release profiles demonstrate the feasibility of the encapsulation strategy. Since the encapsulation of proteins was performed at low temperature and after the preparation of microgels, organic solvent and high temperature were completely avoided in drug encapsulation. FTIR, Raman and circular dichroism measurements confirmed that the ordered structure of proteins was not destroyed during encapsulation and after release. Thus, the post-fabrication encapsulation technique in this paper is much unique and beneficial for controlled release of biomacromolecular drugs.

Circular Dichroism↗

PubMed2005

[Human adipose derived stem cells suppress lymphocyte proliferation induced by cellular or nonspecific mitogenic stimuli].

OBJECTIVE: To study immunological properties of adipose derived stem cells (ADSC) and their in vitro immunomodulatory effects on lymphocytes. METHODS: ADSC was isolated from fat tissue by liposuction and culture expanded. Cells at passage 2 were observed for the expression of HLAI, HLAII by FACs analysis. Peripheral blood lymphocytes (PBL) were cultured with allogeneic ADSCs at dose of 1 x 10(5). A third-party ADSCs at dose of 1 x 10(2), 1 x 10(3), 1 x 10(4), 1 x 10(5) were added to the ongoing two-way mixed lymphocyte reactions (MLR) for 6 days. Value of CPM (count per minute) was calculated with luminescence counter. RESULTS: Flow cytometry showed that undifferentiated ADSCs express HLA class I but not class II. Addition of interferon gamma (IFN-gamma) for 48 hours induced greater than 90% of cells to express HLA class II. No lymphocyte response was induced by allogeneic ADSCs as stimulators. Results were similar using ADSCs pretreated with IFN-gamma. ADSCs elicited inhibit function of mixed lymphocyte cultures in a dose dependent way. Even if ADSCs were pretreated with IFN-gamma, the suppression ability was maintained. CONCLUSION: Undifferentiated ADSCs do not elicit alloreactive lymphocyte proliferative responses and could modulate immune responses in vitro.

Adipocytes↗

PubMed2005

[Experimental study of compatibility between chondrocytes and allogenic cartilage microparticle acellular tissue matris in vitro].

OBJECTIVE: To construct tissue engineered cartilage using cartilage microparticle acellular tissue matrix (CMACTM) as scaffold. METHODS: To determine the content of hydroxyproline, glycosaminoglycan and DNA of CMACTM prepared from sheep's articular cartilage with multistep enzymic method, and to analyze CMACTM with gross observation, histology and scanning electron microscopy. Allogenic chondrocytes were mixed with CMACTM and cultured in vitro from 0 to 35 days. Observations through inverted microscope, scanning and transmission electron microscope, quantifications of hydroxyproline, glycosaminoglycan and DNA in the composite, cells adhesion rate were applied to analyze the results. RESULTS: The diameter of CMACTM was 0.100-0.154 mm, which contain extracellular matrix only. Hydroxyproline, glycosaminoglycan and DNA quantifications in CMACTM were 204.374 +/- 3.120 microg/mg, 18.302 +/- 2.037 microg/mg and 0.042 +/- 0.013 microg/mg respectively. Allogenic chondrocytes enclosed CMACTM tightly, hydroxyproline, glycosaminoglycan and DNA quantifications in the composite of the two formers increased with difference on 7th day compared with that on 0 day, reached to the peaks on 14th day (hydroxyproline, DNA) and on 21st day (glycosaminoglycan), and retained at a high level on the following days. Cells adhesion rate was 92%. CONCLUSION: Allogenic CMACTM possessed satisfactory biocompatibility for chondrocytes and provided a new scaffold for cartilage tissue engineering.

Animals↗

PubMed2005

NBS1 knockdown by small interfering RNA increases ionizing radiation mutagenesis and telomere association in human cells.

Hypomorphic mutations which lead to decreased function of the NBS1 gene are responsible for Nijmegen breakage syndrome, a rare autosomal recessive hereditary disorder that imparts an increased predisposition to development of malignancy. The NBS1 protein is a component of the MRE11/RAD50/NBS1 complex that plays a critical role in cellular responses to DNA damage and the maintenance of chromosomal integrity. Using small interfering RNA transfection, we have knocked down NBS1 protein levels and analyzed relevant phenotypes in two closely related human lymphoblastoid cell lines with different p53 status, namely wild-type TK6 and mutated WTK1. Both TK6 and WTK1 cells showed an increased level of ionizing radiation-induced mutation at the TK and HPRT loci, impaired phosphorylation of H2AX (gamma-H2AX), and impaired activation of the cell cycle checkpoint regulating kinase, Chk2. In TK6 cells, ionizing radiation-induced accumulation of p53/p21 and apoptosis were reduced. There was a differential response to ionizing radiation-induced cell killing between TK6 and WTK1 cells after NBS1 knockdown; TK6 cells were more resistant to killing, whereas WTK1 cells were more sensitive. NBS1 deficiency also resulted in a significant increase in telomere association that was independent of radiation exposure and p53 status. Our results provide the first experimental evidence that NBS1 deficiency in human cells leads to hypermutability and telomere associations, phenotypes that may contribute to the cancer predisposition seen among patients with this disease.

Apoptosis↗

PubMed2005

Hysterectomy prevalence and cardiovascular disease risk factors in American Indian women.

OBJECTIVES: We investigated hysterectomy prevalence and associated demographic and reproductive factors among American Indian women. The association between hysterectomy and cardiovascular disease (CVD) risk factors was also examined. METHODS: Data were from 2689 American Indian women who participated in the first examination of the Strong Heart Study from 1989 to 1992. Odds ratios were estimated for factors related to hysterectomy adjusting for other covariates. The association between hysterectomy and CVD risk factors was examined among 1726 eligible women using analysis of covariance. RESULTS: Hysterectomy prevalence ranged from 24% to 34% across differing age groups and the percent with oophorectomy among those with a hysterectomy ranged from 43% to 63%. Geographic area, more prior pregnancy losses, more education, and less speaking of the native language were associated with increased hysterectomy prevalence. After adjustment for age, the women who had a hysterectomy with intact ovaries had higher total cholesterol and low-density lipoprotein cholesterol levels than those with a natural menopause. CONCLUSIONS: American Indian women have comparable hysterectomy prevalence as non-Hispanic white women. Education and native language speaking related to hysterectomy in this population. Hysterectomy alone may relate to unfavorable changes of lipid profile.

Aged↗

PubMed2005

Repulsive guidance molecule (RGMa), a DRAGON homologue, is a bone morphogenetic protein co-receptor.

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor beta (TGF-beta) superfamily of ligands, which regulate many mammalian physiologic and pathophysiologic processes. BMPs exert their effects through type I and type II serine/threonine kinase receptors and the Smad intracellular signaling pathway. Recently, the glycosylphosphatidylinositol (GPI)-anchored protein DRAGON was identified as a co-receptor for BMP signaling. Here, we investigate whether a homologue of DRAGON, repulsive guidance molecule (RGMa), is similarly involved in the BMP signaling pathway. We show that RGMa enhances BMP, but not TGF-beta, signals in a ligand-dependent manner in cell culture. The soluble extracellular domain of RGMa fused to human Fc (RGMa.Fc) forms a complex with BMP type I receptors and binds directly and selectively to radiolabeled BMP-2 and BMP-4. RGMa mediates BMP signaling through the classical BMP signaling pathway involving Smad1, 5, and 8, and it up-regulates endogenous inhibitor of differentiation (Id1) protein, an important downstream target of BMP signals. Finally, we demonstrate that BMP signaling occurs in neurons that express RGMa in vivo. These data are consistent with a role for RGMa as a BMP co-receptor.

Amino Acid Sequence↗

PubMed2005

[Role of molecular screening for common fusion genes in the diagnosis and classification of leukemia].

OBJECTIVE: To assess the value of common fusion genes analysis in the diagnosis and classification of leukemia by multiplex RT-PCR. METHODS: The multiplex RT-PCR, including 8 parallel PCR reactions, could screen 86 mRNA breakpoints or splice variants at the same time, which was important for the diagnosis and prognosis of leukemia. Bone marrow samples from 161 cases of leukemia and 8 cases of myelodysplastic syndrome (MDS) were involved in the study. The distribution of common fusion genes in leukemia was analyzed by the method mentioned above in combination with clinical and morphological features. RESULTS: Ten fusion genes were detected in 115 cases of leukemia, including AML1/ETO, PML/RAR alpha, PLZF/RAR alpha, dupMLL, MLL/AF6, MLL/AF10, CBFbeta/MYH11, BCR/ABL, Hox11, and EVI1 BCR/ABL was positive in all the 52 cases of chronic myeloid leukemia; PML/RAR alpha was found in 21 of 25 acute promyelocytic leukemia (APL), and PLZF/RAR alpha was detected in one case of APL. Sixteen cases of 17 AML1/ETO-positive acute leukemia (AL) belonged to FAB-M2 subtype, and one case was mixed leukemia. Three of 4 AL cases carrying CBFbeta/MYH11 were M4 subtype, and one was M5 subtype. MLL aberrations were found in 16 AL, in which all MLL/AF6 translocation existed in M5 subtype with classic monoblastic characters. Furthermore, BCR/ABL was detected in 5 acute lymphoblastic leukemia (ALL) cases. Fusion genes were also found in 2 MDS cases, of which AML1/ETO positive-MDS-RAEB progressed to AML rapidly. CONCLUSION: Screening of common fusion genes by multiplex RT-PCR is an important tool which could provide useful and reliable molecular genetic information for the diagnosis and treatment of leukemia.

Adolescent↗