Biomedical subjects

Qin Wang

Publications and source records attributed to Qin Wang.

At least 91 records · Page 5Linked to original sources

PubMed2004

Natural history of bone complications in men with prostate carcinoma initiating androgen deprivation therapy.

BACKGROUND: As evidence accumulates in favor of androgen deprivation therapy (ADT) in patients with recurrent or metastatic prostate carcinoma, concern has increased regarding bone loss associated with therapeutic hypogonadism. The current study described the natural history of bone complications in men with prostate carcinoma who have initiated ADT. METHODS: Using 1992-2001 claims data from a 5% national random sample of Medicare beneficiaries, the authors identified men with prostate carcinoma who initiated ADT between 1992 and 1994. They analyzed inpatient, outpatient, and physician claims for bone complications over 7 subsequent years. They stratified the quartile of patients who survived longest into 2 cohorts: those who had received ADT for longer than and those who had received ADT for shorter than the median of 697 days. They evaluated the cumulative proportions of patients in each cohort with claims for pathologic fractures, osteoporosis/osteopenia, and nonpathologic fractures. RESULTS: In the 1992-1994 sample, 4494 men with prostate carcinoma initiated ADT. Of these, 1126 survived > 2028 days (5.5 years). During the first 3 years of evaluation, the proportion of bone events was similar for men with shorter durations of ADT and men with longer durations of ADT. However, by 7 years, more men in the longer ADT cohort (45%) had sustained at least 1 pathologic or nonpathologic fracture compared with men in the shorter ADT cohort (40%). CONCLUSIONS: In the current study, men with prostate carcinoma were found to be at risk for adverse bone effects from both the disease and the treatment. These longitudinal data revealed that fractures are common in this patient population and appear to be linked to the duration of ADT.

Adenocarcinoma↗

PubMed2004

A group II intron-encoded maturase functions preferentially in cis and requires both the reverse transcriptase and X domains to promote RNA splicing.

Mobile group II introns encode proteins with both reverse transcriptase activity, which functions in intron mobility, and maturase activity, which promotes RNA splicing by stabilizing the catalytically active structure of the intron RNA. Previous studies with the Lactococcus lactis Ll.LtrB intron suggested a model in which the intron-encoded protein binds first to a high-affinity binding site in intron subdomain DIVa, an idiosyncratic structure at the beginning of its own coding region, and then makes additional contacts with conserved catalytic core regions to stabilize the active RNA structure. Here, we developed an Escherichia coli genetic assay that links the splicing of the Ll.LtrB intron to the expression of green fluorescent protein and used it to study the in vivo splicing of wild-type and mutant introns and to delineate regions of the maturase required for splicing. Our results show that the maturase functions most efficiently when expressed in cis from the same transcript as the intron RNA. In agreement with previous in vitro assays, we find that the high-affinity binding site in DIVa is required for efficient splicing of the Ll.LtrB intron in vivo, but in the absence of DIVa, 6-10% residual splicing occurs by the direct binding of the maturase to the catalytic core. Critical regions of the maturase were identified by statistically analyzing ratios of missense to silent mutations in functional LtrA variants isolated from a library generated by mutagenic PCR ("unigenic evolution"). This analysis shows that both the reverse transcriptase domain and domain X, which likely corresponds to the reverse transcriptase thumb, are required for RNA splicing, while the C-terminal DNA-binding and DNA endonuclease domains are not required. Within the reverse transcriptase domain, the most critical regions for maturase activity include parts of the fingers and palm that function in template and primer binding in HIV-1 reverse transcriptase, but the integrity of the reverse transcriptase active site is not required. Biochemical analysis of LtrA mutants indicates that the N terminus of the reverse transcriptase domain is required for high-affinity binding of the intron RNA, possibly via direct interaction with DIVa, while parts of domain X interact with conserved regions of the catalytic core. Our results support the hypothesis that the intron-encoded protein adapted to function in splicing by using, at least in part, interactions used initially to recognize the intron RNA as a template for reverse transcription.

Base Sequence↗

PubMed2004

Spinophilin blocks arrestin actions in vitro and in vivo at G protein-coupled receptors.

Arrestin regulates almost all G protein-coupled receptor (GPCR)-mediated signaling and trafficking. We report that the multidomain protein, spinophilin, antagonizes these multiple arrestin functions. Through blocking G protein receptor kinase 2 (GRK2) association with receptor-Gbetagamma complexes, spinophilin reduces arrestin-stabilized receptor phosphorylation, receptor endocytosis, and the acceleration of mitogen-activated protein kinase (MAPK) activity following endocytosis. Spinophilin knockout mice were more sensitive than wild-type mice to sedation elicited by stimulation of alpha2 adrenergic receptors, whereas arrestin 3 knockout mice were more resistant, indicating that the signal-promoting, rather than the signal-terminating, roles of arrestin are more important for certain response pathways. The reciprocal interactions of GPCRs with spinophilin and arrestin represent a regulatory mechanism for fine-tuning complex receptor-orchestrated cell signaling and responses.

Adenosine↗

PubMed2004

Thrombin and lysophosphatidic acid receptors utilize distinct rhoGEFs in prostate cancer cells.

Thrombin and lysophosphatidic acid (LPA) receptors play important roles in vascular biology, development, and cancer. These receptors activate rho via G(12/13) family heterotrimeric G proteins, which are known to directly activate three distinct rho guanine nucleotide exchange factors (rhoGEFs) that contain a regulator of G protein signaling (RGS) domain (RGS-rhoGEFs). However, it is not known which, if any, of these RGS-rhoGEFs (LARG (leukemia-associated rhoGEF), p115rhoGEF, or PDZrhoGEF) plays a role in G protein-coupled receptor-stimulated rho signaling. Using oligonucleotide small interfering RNAs that suppress specific RGS-rhoGEF expression, we show that thrombin receptor stimulation of rho is primarily mediated by LARG in HEK293T and PC-3 prostate cancer cell lines. In contrast, the LPA-stimulated rho response in PC-3 cells is dependent on PDZrhoGEF expression. Suppression of p115rhoGEF had no effect. Thus different rhoGEFs (LARG and PDZrhoGEF) mediate downstream rho signaling by the thrombin and LPA receptors.

Cell Line, Tumor↗

PubMed2004

All-trans retinoic acid potentiates Taxotere-induced cell death mediated by Jun N-terminal kinase in breast cancer cells.

Taxotere is a cytotoxin effective in treating breast and prostate cancer. It stabilizes microtubules and causes catastrophic cell cycle arrest in G2/M. Taxanes also initiate apoptosis by activating signal pathways, such as the jun N-terminal kinase (JNK) pathway. Strategies aimed at potentiating cell death signaling may improve their efficacy while lessening the potential side effects. We reported that all-trans retinoic acid (ATRA) potentiated taxane-mediated cell death. Here we investigated whether ATRA potentiates cell death signaling through the JNK pathway. Activation of JNK by Taxotere 0.01, 0.1 and 1.0 microM was observed at 24 h in adherent cells and increased at 48 h. Taxotere 0.001 microM-induced JNK activation started after 48 h and increased at 72 h. The timing and intensity of PARP cleavage was similar to that of JNK activation. JNK activation and PARP cleavage induced by 30 nM Taxotere at 48 h were reversed by curcumin, PD169316 and SP600125, JNK inhibitors in order of progressive specificity. None of these inhibitors had an effect on p38 or ERK phosphorylation. All three inhibitors reversed Taxotere-induced phosphorylation of Bcl-2. ATRA induced JNK activation at 24, 48 and 72 h. Incubating cells with ATRA 0.01 microM for 3 days prior to Taxotere treatment potentiated Taxotere-induced JNK activation 24 and 48 h later, an effect sustained for 72 h. Cytotoxicities from 3-day ATRA 0.01 microM incubations were synergistic with subsequent 1-h Taxotere 0.01, 0.1 and 1.0 microM incubations in breast cancer cell lines MCF-7 and MDA-MB-231 and in prostate cancer cell lines LNCaP and PC-3, and additive in breast cancer cell line SK-Br-3. These data demonstrate the potentiation of Taxotere-induced cell death by ATRA pretreatment in breast and prostate cancer cells, and support a mechanism through accentuated and sustained JNK activation.

Breast Neoplasms↗

PubMed2004

A rapid temperature-responsive sol-gel reversible poly(N-isopropylacrylamide)-g-methylcellulose copolymer hydrogel.

Poly(N-isopropylacrylamide) (PNIPAAm) was grafted to methylcellulose (MC) with various feeding ratios using ammonium persulfate and N,N,N',N'-tetramethyl ethylene diamine as an initiator. FTIR results confirm the formation of PNIPAAm-g-MC copolymers. The temperature responsiveness of copolymer gels was investigated by turbidimetry, dynamic contact angle (DCA), differential scanning calorimetry and dynamic mechanical analysis (DMA). The results indicate that PNIPAAm-g-MC hydrogels are strongly temperature responsive. At lower contents of MC, the lower critical solution temperature (LCST) is decreased, whereas further increasing MC contents raises the LCSTs. It is observed that the phase transition of the hydrogels occurs reversibly within 1 min, and near body temperature, a rigid gel can be generated in a certain range of MC content. What is more, the incorporation of MC prevents the syneresis of copolymer hydrogel. DMA measurement reveals that the storage moduli (E') of the gels increase upon increasing MC contents, and moreover the values of E' go up markedly above LCST. The copolymer hydrogels hold a promise as a blood vessel barrier by tuning gelation temperature, gelation time and mechanical strength.

Acrylic Resins↗

PubMed2004

Enhanced antitumor immunity by murine cytokine activated T lymphocytes after cocultured with bone marrow derived dendritic cells pulsed with whole tumor lysates.

Human cytokine induced killer cells (CIK) have shown potent non-major histocompatibility (MHC)-restricted antitumor activity in vitro in recent years. Using a similar protocol, we generated murine cytokine activated T lymphocytes (CAT) from splenocytes with the sequential addition of IFN-gamma, IL-1beta, anti-CD3 and IL-2. The NK depleted CATs did not possess significant antitumor activity both in vitro and in vivo. However, after cocultured with dendritic cells (DC) pulsed with whole tumor lysates, significant specific antitumor activity was observed both in vitro and in vivo. Our data demonstrated that the CATs cocultured with dendritic cells pulsed with whole tumor lysates have potent specific antitumor effects and might be useful in the treatment of malignancies.

Animals↗

PubMed2004

Ribozyme- and siRNA-mediated suppression of RGS-containing RhoGEF proteins.

Given recent efforts to determine the sequence information on thousands of genes in the human genome, the current challenge is to identify the functions of these genes, including those encoding the regulator of G-protein signaling protein gene superfamily, and to establish their roles in particular signaling pathways in a native system. Increasingly, reverse genetic approaches are being used to address these questions. This article compares two powerful approaches [ribozyme and "short interfering" RNA (siRNA) techniques] under identical conditions for the first report on the suppression of endogenous RGS domain-containing RhoGEFs. The siRNA technique was found to be much more potent than ribozyme targeting at the same mRNA site of RGS-RhoGEFs. Also, the three siRNAs targeting LARG, PDZ-RhoGEF, and p115-RhoGEF are able to discriminate the closely related sequences within this RGS-RhoGEF gene family.

Amino Acid Sequence↗

PubMed2004

Pharmacological properties of hydrophilic and lipophilic derivatives of octreotate.

Derivatives of somatostatin (SST) represent the most important peptides for receptor targeting in oncological applications. Whereas the pharmacophor in somatostatin receptor-affine substances has been thoroughly investigated, the influence of modifications at the N-terminal has not yet been systematically studied. In order to investigate the influence of hydrophilic versus lipophilic modifications at the N-terminal end, a series of homologous derivatives of Tyr3-octreotate modified with oligomers of ethylene glycol or fatty acids were synthesized. For this purpose, Tyr3-octreotate was assembled using solid phase peptide synthesis and the fatty acids or oligomers of ethylene glycol were conjugated to the N-terminal end. The oligomers of ethylene glycol were activated by 4-nitrophenylchloroformate to obtain carbamate-linked hydrophilic compounds. The receptor affinities of these compounds were determined by competition experiments with [125I]Tyr3-octreotide on rat cortex membranes. The hydrophilic derivatives and the short chain lipophilic derivatives revealed IC50 values between 0.66 +/- 0.02 nM and 2.16 +/- 0.31 nM respectively. After labeling with (125)I the organ distribution of selected derivatives was investigated in Lewis rats bearing the rat pancreatic tumor CA20948. All of the compounds showed high tumor uptake. The peptides conjugated to oligomers of ethylene glycol showed low uptake into the liver and kidneys. Increasing the length of the fatty acids resulted in a remarkable decrease in kidney uptake. In conclusion, the systematic modifications at the N-terminal result in a low effect on the receptor affinity but allow the modulation of the pharmacokinetic properties of octreotide derivatives.

Animals↗

PubMed2004

Enzymatic characterization and functional groups of polyphenol oxidase from the pupae of blowfly (Sarcophaga bullata).

Polyphenol oxidase (EC 1.14.18.1) was purified from the pupae of blowfly (Sarcophaga bullata) by a procedure involving ammonium sulfate fractionation and chromatography on DEAE-cellulose and Sephadex G-100. Kinetic characteristics of the enzyme were determined using L-DOPA as substrate. The specific activity of the enzyme was 770 U/mg, and the Michaelis constant (Km) was 1.5 +/- 0.1 mM (pH 6.8, 30 degrees C). Activity was maximal at 40 degrees C, pH 6.5. Chemical modification experiments demonstrated that cysteine and tryptophan residues are essential and arginine residues are not essential to the enzyme function. The enzyme is inhibited by quercetin with an IC50 of 0.20 +/- 0.06 mM. The inhibition is of competitive type, and the inhibition constant was determined to be 88 micro M.

Animals↗

PubMed2004

Inhibitory effects of 4-halobenzoic acids on the diphenolase and monophenolase activity of mushroom tyrosinase.

The effects of 4-halobenzoic acids (4-fluorobenzoic acid, 4-chlorobenzoic acid, and 4-bromobenzoic acid) on the activity of mushroom tyrosinase have been studied. The results show that 4-halobenzoic acids can strongly inhibit both monophenolase activity and diphenolase activity of the enzyme, and the inhibition displays a reversible course. The IC50 values were estimated as 0.26, 0.20, and 0.18 mM for diphenolase activity and as 1.03, 0.75, and 0.60 mM for monophenolase activity, respectively. Kinetic analyses show that the inhibition mechanism of all three 4-halobenzoic acids is noncompetitive inhibition to the diphenolase activity, and the inhibition constants (K1) were determined to be 0.25, 0.20, and 0.17 mM, respectively. The lag time of the monophenolase was obviously lengthened by these three 4-halobenzoic acids. When the concentration of inhibitors reached 1.4 mM, the lag time was lengthened from 30 s to 120, 125, and 150 s, respectively.

Agaricales↗

PubMed2004

Neutrophils in innate immunity.

Neutrophils are an important component of innate immunity in the lungs. During bacterial pneumonia, neutrophils are recruited from the capillaries of the pulmonary circulation in the gas-exchanging regions of the lungs. This process requires the coordinated activation of many cells within the lungs, including neutrophils and capillary endothelial cells. Cellular activation during innate immune responses is mediated in part by tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1-initiated signaling through their receptors, activation of nuclear factor kappa B (NF-kappaB) and downstream gene transcription, endothelial cell signaling initiated by neutrophil adherence to intercellular adhesion molecule (ICAM)-1, and binding of leukocyte adhesion molecules to cellular and matrix ligands. These events are essential to effective host defense during pneumonia.

Journal Article↗

PubMed2004

Human recombinant B7-H3 expressed in E. coli enhances T lymphocyte proliferation and IL-10 secretion in vitro.

To explore the biofunctions of human B7-H3 on activated T lymphocyte, the gene of human B7-H3 encoding the extracellular region (IgV-like and IgC-like domains) was obtained by RT-PCR from human lung cells and subcloned into the prokaryotic expression vector pGEX-5X-3 to express glutathione S-transferase (GST) fusion protein. A 49 kD fusion protein (named as GST/hB7-H3 hereafter) was induced by IPTG and purified by standard methods reported in prokaryotic system. In the presence of the first signal imitated by anti-CD3 monoclonal antibody, T lymphocyte proliferation was observed by incubating purified T cells with soluble GST/hB7-H3 fusion protein by MTT assay. The concentrations of IFN-gamma and IL-10 in the supernatants of T cells were determined by ELISA. The results showed that the GST/hB7-H3 protein produced in bacteria had modest biological activities to proliferate the T lymphocyte and enhance IFN-gamma as well as IL-10 secretion.

Antibodies, Monoclonal↗

PubMed2004

Membrane trafficking of G protein-coupled receptors.

G protein-coupled receptors (GPCRs) modulate diverse physiological and behavioral signaling pathways by virtue of changes in receptor activation and inactivation states. Functional changes in receptor properties include dynamic interactions with regulatory molecules and trafficking to various cellular compartments at various stages of the life cycle of a GPCR. This review focuses on trafficking of GPCRs to the cell surface, stabilization there, and agonist-regulated turnover. GPCR interactions with a variety of newly revealed partners also are reviewed with the intention of provoking further analysis of the relevance of these interactions in GPCR trafficking, signaling, or both. The disease consequences of mislocalization of GPCRs also are described.

Animals↗

PubMed2004

Ribozymes as tools for suppression of G protein gamma subunits.

RNA suppression approaches provide a rapid survey of gene function. Of these approaches (i.e., antisense oligonucleotides, ribozymes, and RNA interference), ribozymes offer significant advantages by operating as stringent site-specific ribonucleases. The purpose of this chapter is to provide some guidelines and protocols for the use of ribozymes to identify the functions of closely related members of the G protein gamma subunit family. Improvements in their design and delivery will be discussed, including the use of "second generation" ribozymes targeted against multiple cleavage sites.

Animals↗

PubMed2004

Study of G-protein-coupled receptor-protein interactions using gel overlay assays and glutathione-S-transferase-fusion protein pull-downs.

Numerous recent studies have suggested that the predicted cytosolic domains of G-protein-coupled receptors (GPCRs) represent a surface for association with proteins that may serve multiple roles in receptor localization, turnover, and signaling beyond the well-characterized interactions of these receptors with heterotrimeric G-proteins. This chapter describes two in vitro methods for ascertaining interactions between GPCRs and various binding partners: gel overlay strategies and GST-fusion protein pull-downs.

Animals↗

PubMed2004

Different antitumor immunity roles of cytokine activated T lymphocytes from naive murine splenocytes and from dendritic cells-based vaccine primed splenocytes: implications for adoptive immunotherapy.

AIM: The aim of the study is to explore the antitumor capacity of effector cells generated from murine splenocytes with sequential addition of a cocktail of cytokines and the possible contribution of dendritic cells to the antitumor capacity of these effector cells. METHODS AND RESULTS: Interferon-gamma, interleukin (IL)-1 beta, anti-CD3 mAb and IL-2 were used to activate murine splenocytes either from naive mice (termed cytokine activated T cells, CAT) or from DC based vaccine primed mice (termed specific effector T cells, SET). The antitumor roles of SET and CAT were analyzed in murine L615 T lymphocytic leukemia. Both CAT and SET were CD4(+)-predominant phenotypically and didn't show any significant cytotoxicity against a variety of syngeneic and allogeneic target cell lines using 51Cr release assay. When injected in vivo in combination with CY, CAT can cure a large proportion of leukemia mice. The cured mice couldn't establish specific antitumor immunity. However, in contrast to the roles of CAT, SET show far superior antitumor efficacy on a per cell basis compared with CAT. Moreover, the SET cured mice developed tumor specific long term memory immunity which was sufficient to reject a subsequent otherwise lethal tumor cells rechallenge and was transferable to naive immunocompetent mice. CONCLUSION: Our data demonstrate that there remain fundamentally different antitumor functions of CAT and SET which might be useful in the immunotherapy strategy choices.

Animals↗

PubMed2004

CD4+ T cells tumor specific response exists in L615 leukemia mice: adoptive transfer in combination with cyclophosphamide.

AIM: L615 leukemia cell line is a transplantable acute lymphocytic leukemia model with the CD4 positive phenotype. In this study, we explored whether tumor response specific T cells can be separated from the live leukemia mice or not. METHODS: The mutant HGPRT- L615 cell line was first established. The splenocytes from HGPRT- L615 leukemia mice were cultured and expanded in mixed tumor-lymphocytes culture manner. The expanded T cells were sorted with FACScan. Then their killing capacity, IFN-gamma release as well as antitumor capacity in adoptive transfer experiments were analyzed. RESULTS: The expanded response T cells are mostly CD4 positive. The CD4 positive T cells showed high release of IFN-gamma upon stimulation but lacked significant cytotoxicity. In immunochemotherapy model, these CD4 positive T cells can cure most leukemia mice. CONCLUSIONS: We demonstrated the feasibility of separation of tumor response specific CD4+ T cells from CD4+ L615 leukemia mice. These CD4+ T cells can cure leukemia mice upon adoptive transfer in combination with cyclophosphamide pretreatment.

Adoptive Transfer↗