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B Wang

Publications and source records attributed to B Wang.

At least 253 records · Page 14Linked to original sources

A coumarin-based prodrug strategy to improve the oral absorption of RGD peptidomimetics.

In recent years, major progress has been made in the design and synthesis of fibrinogen antagonists, which are peptidomimetic Arg-Gly-Asp (RGD) analogs. These RGD analogs are very promising antiplatelet agents. However, the clinical development of orally active RGD analogs has been hindered by the low oral bioavailability of many such RGD analogs. Aimed at enhancing their oral bioavailability, we have synthesized several coumarin-based cyclic prodrugs of RGD analogs, which have the two most polar functional groups, a carboxyl and an amino group, masked as an ester and an amide, respectively. As expected, these cyclic prodrugs have higher membrane interaction potentials as estimated by determining their partitioning between aqueous buffer and an immobilized artificial membrane than the corresponding RGD analogs. Consequently, these cyclic prodrugs are 5-6-fold more able to permeate monolayers of Caco-2 cells, an in vitro cell culture model of the intestinal mucosa barrier. Preliminary studies using dog also indicate the promising potential of using this coumarin-based prodrug strategy to improve the oral bioavailability of such RGD analogs.

Animals↗

Photoalignment of liquid crystals by liquid crystals

We observed light-induced alignment of the nematic liquid crystal, 4, 4(')-n-pentylcyanobiphenyl (5CB), on a fused quartz. Irradiation of the adsorbed layer with polarized ultraviolet light produced homogeneous alignment in a 5CB-filled liquid crystal cell with the easy orientation axis perpendicular to the polarization direction. The measured anchoring energy increases with illumination up to 10(-4) erg/cm (2). Phase retardation and pretilt measurements confirmed near homogeneous alignment of the LC in a cell, while the polarization dependence of second harmonic generation suggested a near normal alignment of the adsorbed layer. We believe that light-induced rearrangement or phototransformation of the adsorbed layer causes the observed phenomenon.

Journal Article↗

Hedgehog-regulated processing of Gli3 produces an anterior/posterior repressor gradient in the developing vertebrate limb.

Ci/Gli zinc finger proteins mediate the transcriptional effects of Hedgehog protein signals. In Drosophila, Ci action as transcriptional repressor or activator is contingent upon Hedgehog-regulated, PKA-dependent proteolytic processing. We demonstrate that PKA-dependent processing of vertebrate Gli3 in developing limb similarly generates a potent repressor in a manner antagonized by apparent long-range signaling from posteriorly localized Sonic hedgehog protein. The resulting anterior/posterior Gli3 repressor gradient can be perturbed by mutations of Gli3 in human genetic syndromes or by misregulation of Gli3 processing in the chicken mutant talpid2, producing a range of limb patterning malformations. The high relative abundance and potency of Gli3 repressor suggest specialization of Gli3 and its products for negative Hedgehog pathway regulation.

Animals↗

R-Ras contains a proline-rich site that binds to SH3 domains and is required for integrin activation by R-Ras.

R-Ras contains a proline-rich motif that resembles SH3 domain-binding sites but that has escaped notice previously. We show here that this site in R-Ras is capable of binding SH3 domains and that the SH3 domain binding may be important for R-Ras function. A fusion protein containing the SH3 domains of the adaptor protein Nck interacted strongly with the R-Ras proline-rich sequence and with the intact protein. The binding was independent of whether R-Ras was in its GDP or GTP form. The Nck binding, which was mediated by the second of the three SH3 domains of Nck, was obliterated by mutations in the proline-rich sequence of R-Ras. The interaction of Nck with R-Ras could also be shown in yeast two-hybrid assays and by co-immunoprecipitation in human cells transfected with Nck and R-Ras. Previous results have shown that the expression of a constitutively active R-Ras mutant, R-Ras(38V), converts mouse 32D monocytic cells into highly adherent cells. Introducing the proline mutations into R-Ras(38V) suppressed the effect of R-Ras on 32D cell adhesion while not affecting GTP binding. These results reveal an unexpected regulatory pathway that controls R-Ras through an SH3 domain interaction. This pathway appears to be important for the ability of R-Ras to control cell adhesion.

Amino Acid Sequence↗

HIV-1 strains from a cohort of American subjects reveal the presence of a V2 region extension unique to slow progressors and non-progressors.

OBJECTIVES: To determine the molecular nature of HIV-1 quasispecies and their evolution, in vivo over time, in an American cohort of 22 homosexual men [four rapid progressors (RP), 15 slow progressors (SP) and three long-term non-progressors (LTNP)], infected with HIV-1 between 1982 and 1983, and to assess the possible role of the HIV-1 V2 region extension in HIV disease progression. DESIGN: Genetic and phylogenetic analyses of the V3 region and the nef gene clones over time from uncultured peripheral blood mononuclear cells (PBMC) of American patients with varying HIV disease progression rates. METHODS: Proviral DNA from longitudinally collected uncultured PBMC were subjected to PCR amplification in the nef gene and env V2 and V3 regions, followed by cloning, sequencing and phylogenetic analysis to establish evolutionary relationships between HIV-1 strains over time. RESULTS: Analysis of multiple viral clones showed nef gene deletions/insertions in 10 out of 15 SP, along with the coexistence of intact and defective nef gene lineages in the same individual over time, whereas these nefgene abnormalities were absent from HIV-1 strains from LTNP. Increasing quasispecies diversity in HIV-1 strains, over time, abrogation of a V3 region N-linked glycosylation site in > 60% of the clones, and, importantly, an extended V2 region were unique features of HIV-1 strains from SP and LTNP. CONCLUSIONS: The V2 region extension was unique to only SP and LTNP, and so may have a role in slow progression or non-progression of HIV disease. Increasing genetic diversity in HIV-1 strains in SP and LTNP correlated with the immunocompetent status of the host.

Amino Acid Sequence↗

A recombinant antibody-targeted plasminogen activator with high affinity for activated platelets increases thrombolytic potency in vitro and in vivo.

To increase thrombolytic specificity of urokinase (uPA), we engineered a recombinant chimeric plasminogen activator SZ51Hu-scuPA, which consists of a humanized monoclonal antibody (SZ-51Hu) specifically against P-selectin on activated human platelet and a single-chain urokinase (scuPA). The cDNA, encoding scuPA amino acids 1-411, was inserted in 5' end to 3' end orientation immediately after the CH3 of SZ-51Hu heavy-chain sequence in the expression vector alphaLys30. The resulting construct alphaLys30-SZ51VH/Hu-scuPA was used to transfect into SP2/0 murine myeloma cell line, which was pretransfected with SZ51Hu light chain. The fusion protein SZ51Hu-scuPA was expressed at 5 mg/L in the supernatant of cell culture. The fusion protein purified by affinity chromatography had a molecular weight of 160 kDa with fibrinolytic activity of 39,000 IU/mg and its affinity to activated human platelet was 67% of the parent murine mAb SZ-51. The thrombolytic property of the fusion protein was first characterized in an in vitro system, which consists of a 125I-fibrin-labeled human plasma clot containing different concentrations of human platelets suspended in citrated human plasma. Fifty percent lysis was reached with SZ51Hu-scuPA in 1 hour at a concentration of 20 IU/mL or in 2 hours at a concentration of 10 IU/ mL, which was much faster than uPA at the same concentration. The maximal lysis of the clots by SZ51Hu-scuPA was 4.1 to 8.4 times more potent than that by uPA. The fusion protein was further characterized in the hamster pulmonary embolism model with clots prepared from fresh platelet-rich human plasma containing 125I-labeled fibrinogen. The thrombolytic activity of SZ51-scuPA was 3.9 times more potent than that of uPA at 2,000 IU/kg in this model. Almost no significant fibrinogen breakdown was observed either in vitro and in vivo.

Animals↗

Naive CD8+ T cells do not require costimulation for proliferation and differentiation into cytotoxic effector cells.

Most current models of T cell activation postulate a requirement for two distinct signals. One signal is delivered through the TCR by engagement with peptide/MHC complexes, and the second is delivered by interaction between costimulatory molecules such as CD28 and its ligands CD80 and CD86. Soluble peptide/MHC tetramers provide an opportunity to test whether naive CD8+ T cells can be activated via the signal generated through the TCR-alphabeta in the absence of any potential costimulatory molecules. Using T cells from two different TCR transgenic mice in vitro, we find that TCR engagement by peptide/MHC tetramers is sufficient for the activation of naive CD8+ T cells. Furthermore, these T cells proliferate, produce cytokines, and differentiate into cytolytic effectors. Under the conditions where anti-CD28 is able to enhance proliferation of normal B6 CD4+, CD8+, and TCR transgenic CD8+ T cells with anti-CD3, we see no effect of anti-CD28 on proliferation induced by tetramers. The results of this experiment argue that given a strong signal delivered through the TCR by an authentic ligand, no costimulation is required.

Animals↗

Comparative contribution of CD1 on the development of CD4+ and CD8+ T cell compartments.

CD1 molecules are MHC class I-like glycoproteins whose expression is essential for the development of a unique subset of T cells, the NK T cells. To evaluate to what extent CD1 contributes to the development of CD4+ and CD8+ T cells, we generated CD1oIIo and CD1oTAPo mice and compared the generation of T cells in these double-mutant mice and IIo or TAPo mice. FACS analysis showed that the number of CD4+ T cells in CD1oIIo mice was reduced significantly compared with the corresponding population in IIo mice. Both CD4+ NK1.1+ and the CD4+ NK1.1- population were reduced in CD1oIIo mice, suggesting that CD1 can select not only CD4+ NK1.1+ T cells but also some NK1.1- CD4+ T cells. Functional analysis showed that the residual CD4+ cells in CD1oIIo can secrete large amounts of IFN-gamma and a significant amount of IL-4 during primary stimulation with anti-CD3, suggesting that this population may be enriched for NK T cells restricted by other class I molecules. In contrast to the CD4+ population, no significant differences in the CD8+ T cell compartment can be detected between TAPo and CD1oTAPo mice in all lymphoid tissues tested, including intestinal intraepithelial lymphocytes. Our data suggest that, unlike other MHC class I molecules, CD1 does not contribute in a major way to the development of CD8+ T cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Body mass index and cardiovascular risk factors in a rural Chinese population.

The metabolic consequences of obesity are well-documented in Western populations. However, limited data are available on the association between body mass index (BMI) and cardiovascular risk factors in developing countries. The authors therefore examined the association between BMI and cardiovascular risk factors in a very lean population in China. A total of 2,542 subjects aged 20-70 years from a rural area of Anqing, China, participated in a cross-sectional survey, and 1,610 provided blood samples in 1993. Mean BMI (kg/m2) was 20.7 for men and 20.9 for women. After adjustment for age, sex, education level, occupation, current alcohol use, and cigarette smoking, BMI was significantly associated with systolic and diastolic blood pressures (p < 0.0001). The adjusted odds ratio for hypertension (systolic pressure > or =140 mmHg or diastolic pressure > or = 90 mmHg) across quintiles of BMI (quintile medians: 18.0, 19.4, 20.6, 21.8, and 24.0) were 1.0, 1.34, 2.46, 2.61, and 4.90 (95% confidence interval: 3.20, 7.50). A higher BMI was directly associated with higher levels of serum total cholesterol, triglycerides, and fasting glucose and lower levels of high density lipoprotein cholesterol. These data from a very lean Chinese population confirm independent relations between body mass and cardiovascular risk factors observed in predominantly overweight Western populations and extend the range of associations to lower BMI levels than do previous studies.

Adult↗

Immune modulation in pemphigus vulgaris: role of CD28 and IL-10.

Pemphigus vulgaris (PV) is an autoimmune bullous skin disease characterized by Abs to the desmosomal cadherin desmoglein-3. Although the autoantibodies have been shown to be pathogenic, the role of the cellular immune system in the pathology of pemphigus-induced acantholysis is unclear. To further delineate the potential role of T cell-signaling pathways in the pathogenesis of PV, we performed passive transfer experiments with PV IgG in gene-targeted mutant mice. Our results demonstrated that CD28-deficient mice (lacking a costimulatory signal for T cell activation) are 5-fold more sensitive to the development of PV than wild-type mice. To evaluate whether the higher incidence of disease was due to an impairment in intercellular adhesion of keratinocytes, we performed an in vitro acantholysis, using CD28-/- mice keratinocytes. No alteration in in vitro adhesion was detected in CD28-/--type keratinocytes. Because the CD28 molecule plays a pivotal role in the induction of Th2 cytokines, we examined the levels of a prototypic Th2 cytokine (IL-10) in CD28-/- mice. Lower levels of IL-10 mRNA were found in lesions from CD28-/- mice. To determine whether pemphigus susceptibility in CD28-/- was related to IL-10 deficiency, we performed passive transfer experiments in IL-10-/- mice that demonstrated increased blisters compared with controls. To confirm that IL-10 is involved in the pathogenesis, rIL-10 was given with PV IgG. IL-10 significantly suppressed the disease activity. These data suggest a potential role of IL-10 in PV.

Acantholysis↗

Evaluation of degradation pathways for plasmid DNA in pharmaceutical formulations via accelerated stability studies.

The stability of highly purified supercoiled plasmid DNA formulated in simple phosphate or Tris-buffered saline solutions has been characterized to establish the overall degradation processes that occur during storage in aqueous solution. Plasmid DNA stability was monitored during accelerated stability studies (at 50 degrees C) by measurements of supercoiled, open-circle, and linear DNA content, as well as the accumulation of apurinic sites and 8-hydroxydeoxyguanosine residues over time. The effects of formulation pH, demetalation, metal ion chelators, and ethanol (hydroxyl radical scavenger) on the supercoiled content of plasmid DNA during storage at 50 degrees C were also determined. The results indicate that free radical oxidation may be a major degradative process for plasmid DNA in pharmaceutical formulations unless specific measures are taken to control it by the addition of free radical scavengers, specific metal ion chelators, or both. The generation of hydroxyl radicals in phosphate-buffered saline was confirmed by examining the hydroxylation of phenylalanine over time by reverse phase high-performance liquid chromatography. Ethanol was found to enhance plasmid DNA stability and to inhibit the hydroxylation of phenylalanine; both observations are consistent with the known ability of ethanol to serve as a hydroxyl radical scavenger. Moreover, the combination of ethylenediamine tetraacetic acid (EDTA) and ethanol had a synergistic enhancing effect on DNA stability. However, the metal ion chelator diethylenetriaminepentaacetic acid (DTPA) was as potent as the combination of EDTA and ethanol for enhancing the stability of plasmid DNA. By controlling free radical oxidation with EDTA and ethanol, the rate constants of plasmid DNA degradation by means of depurination and beta-elimination were then determined, allowing accurate predictions of DNA storage stability as a function of formulation pH and temperature. The ability to predict plasmid DNA storage stability in the absence of free radical oxidation should prove to be a valuable tool for the design of stable pharmaceutical formulations of plasmid DNA.

8-Hydroxy-2'-Deoxyguanosine↗

Effect of food on the pharmacokinetics of osmotic controlled-release methylphenidate HCl in healthy subjects.

The effect of a high-fat meal on the pharmacokinetics of OROS(R) (methylphenidate HCl), an osmotic controlled-release formulation of methylphenidate HCl, was investigated in healthy subjects. Mean peak methylphenidate plasma concentrations occurred slightly later and peak methylphenidate plasma concentrations and AUC values were slightly higher (approximately 10-30%) in the presence of food than in the absence of food. There was no difference in the plasma elimination half-life of methylphenidate between the fed and fasted state. Similarly, peak concentrations and AUC values for alpha-phenyl-2-piperidine acetic acid (PPA; ritalinic acid), the major metabolite of methylphenidate, were slightly higher in the presence of food than in its absence. The 90% confidence interval (CI) for the treatment ratio (fed/fasted) for C(max) was 120.6%-140. 0% for the 18-mg dose and 105.4-119.3% for a 36-mg dose. The 90% CI for the treatment ratio for AUC(infinity) was 114.6-125.7% for the 18-mg dose and 115.1-124.6% for the 36-mg dose. PPA levels were measured following the 18-mg dose and the 90% CI of the treatment ratio was 106.8-115.4% for C(max) and 97.9-103.6% for AUC(infinity). These results indicate the absence of dose dumping from OROS (methylphenidate HCl) in the presence of food. Food does not impede drug absorption and OROS (methylphenidate HCl) may be administered in the fed or fasted state. There were no differences in the adverse event profile between the fed and fasted state.

Administration, Oral↗

Application of in vitro-in vivo correlations (IVIVC) in setting formulation release specifications.

An in vitro-in vivo correlation (IVIVC) was established for an osmotic controlled-release dosage form by deconvolution using data from an immediate-release treatment as the characteristic response. The established IVIVC was evaluated internally (predicting data used to develop the IVIVC) and externally (predicting data not originally included in developing the IVIVC), and the application of the IVIVC in product development was demonstrated. The estimated in vivo dissolution profile compared favorably with the in vitro drug release profile. Good agreement was demonstrated between the estimated and observed cumulative drug release across the entire time course (level A correlation) with low (<10%) predictive error for both C(max) and AUC(infinity). External validation using lots not initially included in the model development compared very well with the observed in vivo profile, with mean prediction errors less than 10% for both C(max) and AUC(infinity). The proposed method demonstrates a schema for developing IVIVCs using data from biostudies routinely conducted during formulation development. The method should facilitate product optimization and can support setting in vitro dissolution specification.

Algorithms↗

Beta(2)-adrenergic receptor overexpression driven by alpha-MHC promoter is downregulated in hypertrophied and failing myocardium.

OBJECTIVE: The alpha-myosin heavy chain (alpha-MHC) promoter is frequently used to direct cardiac specific transgene expression. We studied whether transgene expression controlled by this promoter was altered under conditions of cardiac hypertrophy and failure. METHODS: Transgenic (TG) mice overexpressing human beta(2)-adrenergic receptors (beta(2)AR) and wild type (WT) controls were subjected to thoracic aortic constriction (TAC) or sham operation and studied at 1, 3 and 8 weeks after surgery. RESULTS: Sham operated TG mice had higher heart rates and left ventricular (LV) contractility than WT (all P<0.01), demonstrating enhanced betaAR activation. TAC at 1, 3 and 8 weeks produced progressive LV hypertrophy which was similar between WT and TG mice. Evidence of heart failure was more marked in TG mice with a greater increase in weights of the right ventricle and lungs and a higher prevalence of atrial thrombus (P<0.05 in each case). In hypertrophied TG hearts, endogenous alpha-MHC mRNA transcripts in LV were maintained at 1 and 3 weeks, but were reduced by approximately 40% relative to the sham-operated group at 8 weeks after TAC. Transgene expression, measured as human beta(2)AR mRNA, was reduced by 45% at 1 and 3 weeks and by 70% at 8 weeks after TAC. beta(2)AR binding sites were reduced by 35, 47 and 65%, respectively, at 1, 3 and 8 weeks. CONCLUSION: Cardiac hypertrophy and failure cause downregulation of the endogenous alpha-MHC as well as cardiac specific overexpression of the transgene directed by an alpha-MHC promoter.

Adrenergic beta-Antagonists↗

Age-dependent cardiomyopathy and heart failure phenotype in mice overexpressing beta(2)-adrenergic receptors in the heart.

OBJECTIVE: To explore long-term cardiac phenotype in transgenic (TG) mice with 300-fold overexpression of beta(2)-adrenergic receptors (AR). METHODS: Echocardiography was performed serially on a cohort of wild-type and TG mice (n=26 each) between 4 and 15 months of age. Survival was monitored and autopsy and histological examinations were performed. RESULTS: Heart rate was higher in TG than in wild-type mice throughout the study period. The left ventricular dimensions and fractional shortening were similar between TG and wild-type groups during 4-6 months. Starting at 9 months, however, TG mice showed progressive reduction in fractional shortening and systolic wall thickening, and increase in left ventricular dimensions and left ventricular mass, indicating onset of heart failure, left ventricular hypertrophy and remodeling. Abnormal waveforms in the electrocardiogram and episodes of ventricular ectopic beats were also observed in TG mice. Death of TG mice started at 8.5 months, and the cumulative mortality was 81% by 15 months (P<0.0001 vs. 4% in wild-type mice). The majority of deaths were due to severe heart failure, indicated by cardiac dilatation, lung congestion, pleural effusion and atrial thrombus. Left ventricular sections showed widespread interstitial fibrosis, loss of myocytes and myocyte hypertrophy in TG mice. CONCLUSIONS: A high level of beta(2)AR overexpression results in cardiomyopathy and heart failure. The onset was slower and the expression levels of receptors required are much higher than previously described for the beta(1)AR overexpression.

Aging↗

Autoantigen Ro52 directly interacts with human IgG heavy chain in vivo in mammalian cells.

Previously, when we used in vivo yeast two-hybrid and in vitro protein-protein interaction analyses, we demonstrated a direct interaction between autoantigen Ro52 and the human IgG heavy chain. This interaction occurred in the absence of antibody-antigen specific interaction. Here, by employing a novel strategy, we further demonstrated that Ro52 co-localized with IgG in transfected mammalian cells. The co-localization was specific to IgG1 but not IgG3. Co-immunoprecipitating IgG with Ro52 from transfected cell lysates suggested that protein complex containing Ro52 and IgG contributed to the in vivo co-localization. In addition, IgG from normal human serum was shown to bind to the surface of apoptotic keratinocytes and the binding could be competitively blocked by 50-fold excesses of IgG1, not IgG3. With a direct binding study, we also demonstrated that IgG1 could bind to the surface of apoptotic cells while IgG3 bound barely. This binding was not competed by Fcgamma fragments indicating a non-Fcgamma receptor mediated interaction. Finally, in a competition analysis the addition of GST-RFP could reduce the IgG binding to the cell surface. Thus, we suggested that the binding of IgG to the apoptotic keratinocytes might be mediated through the interactions with the surface exposed Ro52. The potential role of forming this protein complex on the apoptotic cells will be discussed.

Animals↗

Effects of a pectic polysaccharide from a medicinal herb, the roots of Bupleurum falcatum L. on interleukin 6 production of murine B cells and B cell lines.

The effect of T-cell-independent B cell mitogen, a pectic polysaccharide, bupleuran 2IIc, from a medicinal herb, the roots of Bupleurum falcatum L. on interleukin 6 (IL-6) production of murine B cells and B cell lines was investigated in order to clarify the mechanism of enhanced immunoglobulin (Ig) secretion from B cells. Bupleuran 2IIc enhanced IgM secretion from highly purified murine normal B cells. When normal B cells from murine spleen were cultured with bupleuran 2IIc in the presence of anti-IL-6 neutralizing antibody, the enhanced IgM secretion by bupleuran 2IIc was reduced. When B cells were stimulated with bupleuran 2IIc, their IL-6 secretion and the transcription of IL-6 mRNA were enhanced. The enhanced IL-6 secretion by bupleuran 2IIc was also observed in B cell line, Y16 cell. When bupleuran 2IIc was digested with endo-alpha-(1-->4)-D-polygalacturonase, the resulting enzyme resistant carbohydrate portion, "ramified" region (PG-1) composed of rhamnogalacturonan core containing neutral sugar side chains showed potent IL-6 secretion-enhancing activity. These results suggest that the "ramified" region of bupleuran 2IIc stimulates the secretion of IL-6 as the active site, and the resulting IL-6 may partially contribute the enhancement of IgM secretion as an autocrine and/or paracrine mechanism.

Adjuvants, Immunologic↗

Selection of a specific peptide from a nona-peptide library for in vitro inhibition of grass carp hemorrhage virus replication.

Grass carp hemorrhage virus (GCHV), a member of Reoviridae, causes severe hemorrhagic disease of grass carp (Ctenopharyngodon idellus) in China. Icosahedral virions of GCHV were used as to assay the effect of specific peptides for the inhibition of GCHV infectivity. A random nona-peptide library displayed on phage fUSE5 was constructed, and the expressed peptides were fused onto the amino terminus of the minor coat protein III. By biopanning, the fused peptides were bound to the biotinylated GCHV. Phages containing specific peptides bound to GCHV were eluted and amplified in Escherichia coli K91. Three rounds of affinity selection enriched the pool of inhibiting peptides. Sixteen clones which inhibited the replication of GCHV in a grass carp kidney cell line were selected. The TCID(50) of GCHV was decreased over 10000x. Six clones having the strongest inhibitory effect shared the same DNA sequence, with a deduced amino acid sequence of NH(2)-Leu-Trp-Val-Gly-Gly-Gly-Arg-Asn-Ala-COOH. A synthesized nona-peptide of identical sequence exhibited similar inhibitory activity towards GCHV replication in vitro.

Animals↗