Biomedical subjects

Ying Huang

Publications and source records attributed to Ying Huang.

At least 37 records · Page 2Linked to original sources

PubMed2006

Multilocus analyses of Renin-Angiotensin-aldosterone system gene variants on blood pressure at rest and during behavioral stress in young normotensive subjects.

The renin-angiotensin-aldosterone system (RAAS) is a proteolytic cascade that regulates and maintains blood pressure (BP). This study aimed to explore the interactive and integrative effects of multiple RAAS polymorphisms on BP at rest and during behavioral stress in a normotensive population. A total of 920 young white and black twins (age: 12 to 30 years; 45% blacks) was subjected to three 10-minute stress tasks. Thirteen potential functional polymorphisms from 4 major RAAS genes were genotyped. We performed multilocus prediction allowing for genetic modification effects (gene-gene, gene-gender, gene-ethnicity, and gene-body mass index) using Multivariate Adaptive Regression Splines and generalized estimating equations. Single polymorphism analyses showed modest effects of M235T (angiotensinogen) and A-239T (angiotensin I-converting enzyme; P value range: 0.005 to 0.036), accounting for approximately 1% of the total variance of systolic BP at rest and during stress. Compared with this, the best multilocus models revealed multiple independent genetic modification effects (gene-gene, gene-gender, and gene-body mass index; P value range: 0.003 to 0.009), accounting for 2.5% and 7.3% of the total variance for systolic BP levels at rest and during stress, respectively. Our data support the hypothesis that multiple RAAS genetic modifications account for BP variation. We conclude that the RAAS genetic modifications may contribute more to the dynamic BP regulation in response to behavioral stress compared with the static BP value. In addition, we reported a gene-gene interaction between M235T (angiotensinogen) and A1159G (angiotensin I-converting enzyme) on stress systolic BP levels. We proposed a viable approach to test for the multiple genetic contributions to BP and hypertension.

Adolescent↗

PubMed2006

Glucose uptake inhibitor sensitizes cancer cells to daunorubicin and overcomes drug resistance in hypoxia.

PURPOSE: A high-rate glycolysis is a fundamental property of solid tumors and is associated with an over-expression of glucose transporters and glycolytic enzymes. We hypothesize that over-expression of glucose transporters in tumors prevents apoptosis, promotes cancer cell survival, and confers drug resistance. Inhibition of glucose transporter will preferentially sensitize the anticancer effects of chemotherapeutic drugs to overcome drug resistance in hypoxia. METHODS: Glucose transporter expressions were detected in cancer tissues and NCI 60 cancer cells with immunostaining and DNA microarray. Glucose uptake was measured with 3H-2-deoxy-glucose. Cytotoxicity of daunorubicin (DNR) in combination of glucose inhibitor was detected by MTS assay under hypoxic condition. Early stage apoptosis was monitored with Annexin V-FITC staining. RESULTS: Immunostaining showed that GLUT1 was significantly increased in hypoxic regions of the human colon and breast tumors. The expression profiles of all glucose transporters in NCI 60 cancer cells exhibited distinct expression patterns. Phloretin exhibited more than 60% glucose uptake inhibition. Hypoxia conferred two to fivefold higher drug resistance in SW620 and K562 to DNR. Inhibition of glucose uptake by phloretin sensitized cancer cells to DNR for its anticancer activity and apoptosis to overcome drug resistance only under hypoxia. CONCLUSION: Cancer cells heavily rely on glucose transporters for glucose uptake to facilitate a high-rate glycolysis under hypoxia for their survival and drug resistance. Combination of glucose transporter inhibitors and chemotherapeutic drugs may provide a preferential novel therapeutic strategy to overcome drug resistance in hypoxia.

Apoptosis↗

PubMed2006

Field-amplified on-line sample stacking for separation and determination of cimaterol, clenbuterol and salbutamol using capillary electrophoresis.

A capillary electrophoresis method, using field-amplified sample injection (FASI), was developed for separation and determination of some beta 2-agonists, such as cimaterol, clenbuterol and salbutamol. The optimum conditions for this system had been investigated in detail. The precision of the migration time, peak height and accuracy were determined in both intra-day (n = 5) and inter-day (n = 15) assays. Under the optimum conditions, the detection limits (defined as S/N = 3) of this method were found to be lower than 2.0 ng/mL for all of these three beta 2-agonists, which were much lower than that of the conventional electro-migration injection method, the enhancement factors were greatly improved to be 30-40-fold. Such lower detection limit lets this method to be suitable for determination of above-mentioned beta 2-agonists in the urine sample. The mean recoveries in urine were higher than 96.2%, 95.6% and 95.3% for cimaterol, clenbuterol and salbutamol, respectively, with relative standard deviations lower than 3.5%.

Albuterol↗

PubMed2006

Separate RNA-binding surfaces on the multifunctional La protein mediate distinguishable activities in tRNA maturation.

By sequence-specific binding to 3' UUU-OH, the La protein shields precursor (pre)-RNAs from 3' end digestion and is required to protect defective pre-transfer RNAs from decay. Although La is comprised of a La motif and an RNA-recognition motif (RRM), a recent structure indicates that the RRM beta-sheet surface is not involved in UUU-OH recognition, raising questions as to its function. Progressively defective suppressor tRNAs in Schizosaccharomyces pombe reveal differential sensitivities to La and Rrp6p, a 3' exonuclease component of pre-tRNA decay. 3' end protection is compromised by mutations to the La motif but not the RRM surface. The most defective pre-tRNAs require a second activity of La, in addition to 3' protection, that requires an intact RRM surface. The two activities of La in tRNA maturation map to its two conserved RNA-binding surfaces and suggest a modular model that has implications for its other ligands.

Amino Acid Sequence↗

PubMed2006

Ti-Si mixed oxides prepared by polymer in situ sol-gel chemistry with the aid of CO2.

A method to prepare titania-silica binary oxides is proposed in this work. In this route, inorganic precursors tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TIP) were simultaneously or sequentially impregnated into a polypropylene (PP) matrix using supercritical carbon dioxide as a swelling agent and carrier. Hydrolysis and condensation reaction of the precursors confined in a polymer network were induced by treating the composites in 1 mol.dm(-3) (1 M) HCl. Then the PP matrix was decomposed at higher temperature, and titania-silica binary oxides were obtained. The mixed oxides were characterized by X-ray diffraction and Raman, FTIR, and X-ray photoelectron spectroscopy. It was demonstrated that the structure of the oxides depended strongly on the procedure to impregnate the precursors. The simultaneous method, in which the TEOS and TIP were simultaneously impregnated into a PP matrix, resulted in mixed oxides with highly dispersed titanium oxide species in the SiO2 matrix, while the sequential method produced the mixed oxide with separate SiO2 and TiO2 phases which were connected by Ti-O-Si bands at the interface. The method described in this work provides a new route to control the texture of TiO2-SiO2 mixed oxide simply by the impregnation sequence.

Journal Article↗

PubMed2006

Identification of pseudo attP sites for phage phiC31 integrase in bovine genome.

Streptomyces phage phiC31 integrase was found to mediate site-specific integration of foreign genes at pseudo attP sites of genomes in human, mouse, rat, and Drosophila. This paper reports that phiC31 integrase can also mediate homologous recombination between attB and pseudo attP sites in bovine cells and foreign gene integration was increased at least 2-fold in bovine fibroblasts or Madin-Darby bovine kidney (MDBK) cells. Two intrinsic pseudo attP sites named BpsF1 and BpsM1 located in the inter-gene regions on chromosome 28 and 19, respectively, were identified in bovine genome. These pseudo attP sites shared similar characteristics with those from other species as previously described. Our study demonstrated that the phiC31 integrase system provides a new potential for genetic engineering of the bovine genome and might be beneficial for the research on ruminant.

Animals↗

PubMed2006

Thimerosal induces apoptosis in a neuroblastoma model via the cJun N-terminal kinase pathway.

The cJun N-terminal kinase (JNK)-signaling pathway is activated in response to a variety of stimuli, including environmental insults, and has been implicated in neuronal apoptosis. In this study, we investigated the role that the JNK pathway plays in neurotoxicity caused by thimerosal, an ethylmercury-containing preservative. SK-N-SH cells treated with thimerosal (0-10 microM) showed an increase in the phosphorylated (active) form of JNK and cJun with 5 and 10 microM thimerosal treatment at 2 and 4 h. To examine activator protein-1 (AP-1) transcription, cells were transfected with a pGL2 vector containing four AP-1 consensus sequences and then treated with thimerosal (0-2.5 microM) for 24 h. Luciferase studies showed an increase in AP-1 transcriptional activity upon thimerosal administration. To determine the components of the AP-1 complex, cells were transfected with a dominant negative to either cFos (A-Fos) or cJun (TAM67). Reporter analysis showed that TAM67, but not A-Fos, decreased AP-1 transcriptional activity, indicating a role for cJun in this pathway. To assess which components are essential to apoptosis, cells were treated with a cell-permeable JNK inhibitor II (SP600125) or transfected with TAM67, and the downstream effectors of apoptosis were analyzed. Cells pretreated with SP600125 showed decreases in activation of caspases 9 and 3, decreases in degradation of poly(ADP-ribose) polymerase (PARP), and decreased levels of proapoptotic Bim, in comparison to cells treated with thimerosal alone. However, cells transfected with TAM67 showed no changes in those same components. Taken together, these results indicate that thimerosal-induced neurotoxicity occurs through the JNK-signaling pathway, independent of cJun activation, leading ultimately to apoptotic cell death.

Anthracenes↗

PubMed2006

Recognition of histone H3 lysine-4 methylation by the double tudor domain of JMJD2A.

Biological responses to histone methylation critically depend on the faithful readout and transduction of the methyl-lysine signal by "effector" proteins, yet our understanding of methyl-lysine recognition has so far been limited to the study of histone binding by chromodomain and WD40-repeat proteins. The double tudor domain of JMJD2A, a Jmjc domain-containing histone demethylase, binds methylated histone H3-K4 and H4-K20. We found that the double tudor domain has an interdigitated structure, and the unusual fold is required for its ability to bind methylated histone tails. The cocrystal structure of the JMJD2A double tudor domain with a trimethylated H3-K4 peptide reveals that the trimethyl-K4 is bound in a cage of three aromatic residues, two of which are from the tudor-2 motif, whereas the binding specificity is determined by side-chain interactions involving amino acids from the tudor-1 motif. Our study provides mechanistic insights into recognition of methylated histone tails by tudor domains and reveals the structural intricacy of methyl-lysine recognition by two closely spaced effector domains.

Amino Acid Motifs↗

PubMed2006

Antidepressant-like effects of PDE4 inhibitors mediated by the high-affinity rolipram binding state (HARBS) of the phosphodiesterase-4 enzyme (PDE4) in rats.

RATIONALE: Phosphodiesterase-4 (PDE4) has two conformation states based on rolipram binding, the high-affinity rolipram binding state (HARBS) and the low-affinity rolipram binding state (LARBS); their functions remain to be fully explained. OBJECTIVE: Experiments were carried out to determine the roles of the HARBS and LARBS in the mediation of antidepressant-like effects on behavior. MATERIALS AND METHODS: Two animal models sensitive to antidepressant drugs, the forced-swim test (FST), and the differential-reinforcement-of-low-rate (DRL) 72-s operant schedule, were used to examine the antidepressant-like effects of rolipram, CDP840, and piclamilast, PDE4 inhibitors that interact differentially with the HARBS and LARBS, and MEM1018 and MEM1091, two novel PDE4 inhibitors. Drug discrimination vs rolipram and rolipram competition binding assays also were carried out. RESULTS: In the FST, rolipram and piclamilast, both at 0.1 mg/kg, produced an antidepressant-like effect, i.e., reduced immobility and increased swimming, whereas, 1 mg/kg of CDP840 or 0.5 mg/kg of MEM1018 or MEM1091 was required to produce a similar effect. Consistent with this, only rolipram and piclamilast produced antidepressant-like effects in rats under the DRL schedule of reinforcement, as evidenced by decreased response rates and increased reinforcement rates. In addition, in rats trained to discriminate rolipram from its vehicle, only rolipram and piclamilast substituted. Finally, [(3)H]rolipram and [(3)H]piclamilast binding analysis revealed that CDP840 and the two novel PDE4 inhibitors MEM1018 and MEM1091 exhibited a lower affinity for the HARBS than did rolipram. CONCLUSION: These results suggest that the HARBS of PDE4 is the primary conformation important for antidepressant-like effects on behavior.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2006

Alteration of protein subcellular location and domain formation by alternative translational initiation.

Alternative translation is an important cellular mechanism contributing to the generation of proteins and the diversity of protein functions. Instead of studying individual cases, we systematically analyzed the alteration of protein subcellular location and domain formation by alternative translational initiation in eukaryotes. The results revealed that 85.7% of alternative translation events generated biological diversity, attributed to different subcellular localizations and distinct domain contents in alternative isoforms. Analysis of isoelectric point values revealed that most N-terminal truncated isoforms significantly lowered their isoelectric point values targeted at different subcellular localizations, whereas they had conserved domain contents the same as the full-length isoforms. Furthermore, Fisher's exact test indicated that the two ways-targeting at different cellular compartments and changing domain contents-were negatively associated. The N-term truncated isoforms should have only one way to diversify their functions distinct from the full-length ones. The peculiar consequence of subcellular relocation as well as change of domain contents reflected the very high level of biological complexity as alternative usage of initiation codons.

Animals↗

PubMed2006

Calcium-sensing receptor ubiquitination and degradation mediated by the E3 ubiquitin ligase dorfin.

Calcium-sensing receptors (CaR) contribute to regulation of systemic calcium homeostasis by activation of G(q)- and G(i)-linked signaling pathways in the parathyroids, kidney, and intestine. Little is known about the mechanisms regulating CaR synthesis and degradation. Screening of a human kidney yeast two-hybrid library identified the E3 ubiquitin ligase dorfin as a binding partner for the intracellular carboxyl terminus of CaR. Interaction between CaR and dorfin was confirmed by coimmunoprecipitation from HEK293 cells. Ubiquitination of CaR was observed in the presence of the proteasomal inhibitor MG132; mutation of all putative intracellular loop and carboxyl-terminal lysine residues abolished ubiquitination of CaR. Coexpression with dorfin decreased the amount of total CaR protein and increased CaR ubiquitination, whereas a dominant negative fragment of dorfin had opposite effects. The AAA-ATPase p97/valosin-containing protein associates with both CaR and dorfin in HEK293 cells. Treatment with tunicamycin, an inhibitor of N-linked glycosylation, induced the appearance of the unglycosylated 115-kDa CaR form, which was further increased by exposure to MG132, or upon transfection with a dorfin dominant negative construct, suggesting that dorfin-mediated proteasomal degradation of immature CaR occurs from the endoplasmic reticulum. Because endogenous CaR in Madin-Darby canine kidney cells is also subject to degradation from the endoplasmic reticulum, dorfin-mediated ubiquitination may contribute to a general mechanism for CaR quality control during biosynthesis.

Adenosine Triphosphatases↗

PubMed2006

Hypoxia inducible factor-1alpha and leukemic cell differentiation.

Arsenic trioxide (As2O3, ATO) is a recently developed drug for the effective treatment of acute promyelocytic leukemia (APL). Experimental studies showed that in vitro differentiation-inducing ability on APL cells of this drug is not significant compared with its in vivo activity. We unexpectedly found recently that hypoxia-mimetic agents and moderate real hypoxia triggered acute myeloid leukemic cells to undergo differentiation. Furthermore, intermittent hypoxia significantly prolonged the survival of the transplanted leukemic mice with inhibition of infiltration and induction of differentiation of leukemic cells. In the following works, molecular mechanisms of hypoxia-induced differentiation were investigated and some interesting results have been obtained. This review will shortly summarize the related progresses and discuss the questions remained to be further investigated.

Animals↗

PubMed2006

Micropatterned polymer surfaces induced by nonsolvent.

In this work, we present a facile method for fabricating polymer thin films with micropatterned surfaces by evaporating polymer solution containing a small amount of nonsolvent of polymer in air. Poly(methyl methacrylate) (PMMA) and polystyrene (PS) films with densely packed micropores on the surfaces were fabricated. This method was also used to prepare three-dimensional PMMA films with micropatterned surfaces. The effects of nonsolvent content; evaporation temperature; and interactions between the polymer, solvent, and nonsolvent on the specific patterns were investigated, and the formation mechanism of the pores is discussed. This simple route can potentially be used, for example, in the large-scale production of patterned surfaces, three-dimensional painting, and hydrophobicity-enhancing coatings.

Journal Article↗

PubMed2006

Controlled synthesis of Ag/TiO2 core-shell nanowires with smooth and bristled surfaces via a one-step solution route.

Ag/TiO2 core-shell nanowires were synthesized via a one-step solution method without using a template. Interestingly, the shell morphologies can be controlled to be smooth or bristled by altering the reaction temperature. Moreover, the TiO2 shell thickness and bristle length can be tuned by changing the AgNO3 concentration. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), energy-dispersive X-ray analysis (EDS), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize the resultant Ag/TiO2 core-shell nanowires. Moreover, the absorption peaks of our samples are significantly red-shifted compared with those of the uncoated pure silver nanowires, indicating that interaction between the core and shell occurred. On the basis of the experimental results, we proposed a template-induced Oswald ripening mechanism to explain the formation of the Ag/TiO2 core-shell nanowires.

Journal Article↗

PubMed2006

Prediction of anticancer drug potency from expression of genes involved in growth factor signaling.

PURPOSE: This study develops and evaluates a systematic approach to finding biomarker genes for predicting potency of anticancer drugs against tumor cells, focusing on gene families related to growth factor signaling. METHODS: Cytotoxic potencies of 119 drugs against 60 neoplastic cell lines (NCI-60) were correlated with expression of 343 genes, including 90 growth factors and receptors, 63 metalloproteinases, and 92 ras-like GTPases as downstream signaling factors. Progressively more stringent criteria and predictive models aim at identifying the smallest subset of genes predictive of cytotoxic potency. RESULTS: Comparing gene expression with drug potency across the NCI-60 yielded genes with negative and positive correlations (p < 0.001), indicative of a role in chemoresistance and chemosensitivity, respectively. Of 17 genes with multiple negative correlations, 8 are known chemoresistance factors, validating the approach. Negatively correlated genes clustered into two main groups with distinct expression profiles and drug correlations, represented by EGFR and ERBB2 (Her-2/Neu). Accordingly, no synergism was observed between EGFR and ERBB2 inhibitors. However, combinations with classical anticacer drugs were not correlated with EGFR and ERBB2 expression in four cell lines tested, suggesting complex interactions in combination treatments. Finally, a subset of only 13 genes was found to be sufficient for near optimal prediction of drug potency against the NCI-60. CONCLUSIONS: Our approach using a small subset of genes reveals known and potential biomarkers in cancer chemotherapy, providing a strategy for genome-wide analysis.

Algorithms↗

PubMed2006

Translocation of positively charged copoly(Lys/Tyr) across phospholipid membranes.

Much attention has recently been paid to the study of positively charged polypeptides as a possible carrier for therapeutic protein or DNA delivery to cells. In this study, we have investigated the translocation of positively charged copoly(Lys/Tyr) (MW=72000, DP=385) across lipid membranes constituted from egg-phosphatidylcholine (EPC), dioleoyl-phosphatidylethanolamine (DOPE), as well as soybean phospholipids (SBPL) using zeta potential method, circular dichroism spectroscopy (CD), electrophysiology technique, fluorescence spectroscopy, and confocal laser scanning microscopy. Results of zeta potentials show that copoly(Lys/Tyr) associate with lipid membranes and become gradually saturated on the membranes either hydrophobically or electrostatically or both. CD studies demonstrate that the copoly(Lys/Tyr) takes and remains beta-sheet conformation during its interaction with liposome membranes, indicating that the translocation process should be carpet-mode like. Data from the electrophysiology technique reveal that positively charged copoly(Lys/Tyr) can cause transmembrane currents under an applied voltage, confirming its transfer across lipid membranes. Fluorescence spectroscopy results display a three-step mechanism of translocation across membrane: adsorption, transportation, and desorption, which has been verified by results from confocal laser scanning microscopy. We provided the first direct observation that the positively charged polypeptides, copoly(Lys/Tyr), can translocate through SBPL and EPC/DOPE lipid bilayer membranes. In addition, we found that the translocation efficiency of copoly(Lys/Tyr) was higher on the EPC/DOPE lipid membrane than on the SBPL lipid membrane.

Electromagnetic Fields↗

PubMed2006

Mechanistic link between the anti-HCV effect of interferon gamma and control of viral replication by a Ras-MAPK signaling cascade.

Interferon-gamma (IFN-gamma) exerts potent antiviral activity in the hepatitis C virus (HCV) replicon systems. However, the mechanisms underlying the direct antiviral effect have not been determined. We found that the type II transcriptional response to IFN-gamma could be suppressed by inhibition of MEK1/2 kinase activity by MEK1/2 inhibitor U0126 in the hepatoma cell line Huh-7. Using a bicistronic HCV replicon system expressing a luciferase reporter gene in Huh-7 cells (RLuc-replicon), we showed that inhibition of MEK1/2 kinase activity is sufficient to counteract the antiviral activity of IFN-gamma. Expression of a constitutive active form of Ras inhibited the luciferase activity of RLuc-replicon, whereas a dominant-negative mutant of Ras enhanced the reporter activity, indicating that the Ras-MAPK pathway has a role in limiting replication of the viral RNA. Consistent with the involvement of the Ras-MAPK pathway, treatment with epidermal growth factor suppressed HCV protein expression in the RLuc-replicon cells, an effect that could be abolished by U0126. Inhibition of MEK1/2 kinase activity correlated with reduced phosphorylation of the HCV NS5A protein and enhanced RLuc-replicon luciferase reporter activity, in line with recent reports that phosphorylation of NS5A negatively modulates HCV RNA replication. Finally, genetic deletion analysis in yeast supported the role of a MEK-like kinase(s) in the regulation of NS5A phosphorylation. In conclusion, the direct anti-HCV effect of IFN-gamma in cell culture is, at least in part, mediated through the Ras-MAPK signaling pathway, which possibly involves a direct or indirect modulation of NS5A protein phosphorylation.

Antiviral Agents↗

PubMed2006

Field-amplified on-line sample stacking for determination of carnosine-related peptides by capillary electrophoresis.

An on-line sample stacking method, namely field-amplified sample injection, has been developed for the separation and determination of carnosine, anserine, and homocarnosine by capillary electrophoresis. Using electrokinetic injection, about 130- to 160-fold improvement of sensitivity was achieved without loss of separation efficiency when compared to conventional sample injection. For conventional injection, the samples were dissolved in running buffer and then hydrodynamically injected for 10 s (3.45 kPa). Various parameters affecting separation and sample stacking were optimized. Under optimum conditions, linear responses were obtained over two orders of magnitude and the detection limits (defined as S/N = 3) of carnosine, anserine, and homocarnosine were 1.5 x 10(-8) to 1.6 x 10(-8) mol/L.

Anserine↗