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B Wang

Publications and source records attributed to B Wang.

At least 595 records · Page 33Linked to original sources
PubMed1997

Mucosal immunization with a DNA vaccine induces immune responses against HIV-1 at a mucosal site.

Mucosal immunity is the first defense system in protection against mucosal infection by sexually transmitted diseases and subsequent systemic dissemination of infection. Development of vaccines which can induce protective mucosal immunity would have great promise for preventing sexually transmitted diseases including AIDS. DNA vaccines have recently shown certain advantages over other types of vaccines in safety and elicitation of specific immune responses. We have hypothesized that direct delivery of a DNA plasmid coding the HIV-1 envelope (pcMN160) via mucosal routes will stimulate mucosal immunity against HIV-1. The expression of DNA plasmid inoculated intravaginally was detected in various tissues. Intravaginal inoculation of pcMN160 elicits production of vaginal immunoglobulins which specifically bind to the HIV-1 envelope and neutralize HIV-1 infectivity in vitro. These results indicate the feasibility of inducing mucosal immunity following mucosal inoculation of DNA vaccines. When coupled with systemic inoculation of appropriate DNA constructs, effective mucosal and systemic immunity may be generated.

AIDS Vaccines↗
PubMed1997

Development of a multicomponent candidate vaccine for HIV-1.

Nucleic acid or DNA immunization represents a novel approach to both vaccine and immune therapeutic development. DNA vaccination induces antigen-specific cellular and humoral immune responses through the delivery of non-replicating transcription units which drive the synthesis of specific foreign proteins within the inoculated host. We have previously reported on the potential use of DNA immunization as a novel vaccine strategy for HIV-1. We found that both antigen-specific cellular and humoral immune responses could be induced in vivo with various DNA vaccine constructs against different antigenic targets within HIV-1. In order to enhance the DNA vaccine's ability to elicit cell-mediated immune responses, we co-delivered plasmids encoding costimulatory molecule B7 and interleukin-12 genes with DNA vaccine for HIV-1. We observed a dramatic increase in both antigen-specific T helper cell proliferation and CTL response. Eventual development of successful vaccines for HIV-1 would likely involve targeting multiple antigenic components of the virus to direct and empower the immune system to protect the host from viral infection. We present here the utility of multicomponent DNA immunization to elicit specific humoral and cell-mediated immune responses against different antigenic targets of HIV-1 as well as the ability of this immunization strategy to achieve significant enhancements of antigen-specific cellular immune responses.

AIDS Vaccines↗
PubMed1997

Prodrug strategies based on intramolecular cyclization reactions.

Several new prodrug systems for amines, alcohols, and peptides are reviewed. The design of these new prodrug systems takes advantage of several facile intramolecular cyclization reactions, that permit separate manipulation of the release kinetics independent of the structural features of the drug moiety. Such systems can be used for the preparation of esterase-, phosphatase-, and redox-sensitive prodrugs of amines and alcohols and esterase-sensitive cyclic prodrugs of peptides and peptide mimetics.

Animals↗
PubMed1997

Esterase-sensitive cyclic prodrugs of peptides: evaluation of a phenylpropionic acid promoiety in a model hexapeptide.

PURPOSE: To evaluate a cyclic phenylpropionic acid prodrug of a model hexapeptide (H-Trp-Ala-Gly-Gly-Asp-Ala-OH) as a novel approach to enhance the membrane permeation of a peptide and stabilize it to metabolism. METHODS: Conversion to the linear hexapeptide was studied at 37 degrees C in HBSS, pH 7.4, and in various biological milieus having measurable esterase activities. Transport and metabolism characteristics were assessed using the Caco-2 cell culture model. RESULTS: In aqueous buffered solution, pH 7.4, the cyclic prodrug degraded quantitatively (t1/2 = 1795 +/- 289 min) to the linear hexapeptide and the lactone. Substantially faster degradation of the cyclic prodrug was observed in 90% human plasma (t1/2 = 508 +/- 24 min), and in homogenates of Caco-2 cells (t1/2 = 940 +/- 13 min), the rat intestinal mucosa (t1/2 = 1286 +/- 32 min), and rat liver (t1/2 = 840 +/- 42 min). Pretreatment of these biological media with paraoxon significantly decreased the degradation rate of the prodrug. When applied to the apical side of Caco-2 cell monolayers, the cyclic prodrug was significantly more stable than the hexapeptide and at least 71-fold more able to permeate (P(app) = 1.21 +/- 0.12 X 10(-7) cm/s) than was the parent peptide (P(app) < or = 0.17 x 10(-8) cm/s). In the presence of 0.1 mM palmitoyl-DL-carnitine, the transport rate of the cyclic prodrug (P(app) = 2.19 X 10(-6) cm/s) was 1250-fold greater than that of the linear hexapeptide. CONCLUSIONS: Preparation of a cyclic peptide using a phenylpropionic acid promoiety reduced the lability of the peptide to peptidase metabolism and substantially increased its permeation through biological membranes. In various biological media the parent peptide was released from the prodrug by an apparent esterase-catalyzed reaction, sensitive to paraoxon inhibition.

Animals↗
PubMed1997

Engineering of in vivo immune responses to DNA immunization via codelivery of costimulatory molecule genes.

Nucleic acid immunization is a novel vaccination technique to induce antigen-specific immune responses. We have developed expression cassettes for cell surface markers CD80 and CD86, two functionally related costimulatory molecules that play an important role in the induction of T cell-mediated immune responses. Coimmunization of these expression plasmids, along with plasmid DNA encoding for HIV-1 antigens, did not result in any significant change in the humoral response; however, we observed a dramatic increase in cytotoxic T-lymphocyte (CTL) induction as well as T-helper cell proliferation after the coadministration of CD86 genes. In contrast, coimmunization with a CD80 expression cassette resulted in a minor, but positive increase in T-helper cell or CTL responses. This strategy may be of value for the generation of rationally designed vaccines and immune therapeutics.

Animals↗
PubMed1997

Protection of chimpanzees from high-dose heterologous HIV-1 challenge by DNA vaccination.

Novel approaches for the generation of more effective vaccines for HIV-1 are of significant importance. In this report we analyze the immunogenicity and efficacy of an HIV-1 DNA vaccine encoding env, rev and gag/pol in a chimpanzee model system. The immunized animals developed specific cellular and humoral immune responses. Animals were challenged with a heterologous chimpanzee titered stock of HIV-1 SF2 virus and followed for 48 weeks after challenge. Polymerase chain reaction coupled with reverse transcription (RT-PCR) results indicated infection in the control animal, whereas those animals vaccinated with the DNA constructs were protected from the establishment of infection. These studies serve as an important benchmark for the use of DNA vaccine technology for the production of protective immune responses.

AIDS Vaccines↗
PubMed1997

Nucleotide sequence of a gene encoding an organophosphorus nerve agent degrading enzyme from Alteromonas haloplanktis.

Organophosphorus acid anhydrolases (OPAA) catalyzing the hydrolysis of a variety of toxic organophosphorus cholinesterase inhibitors offer potential for decontamination of G-type nerve agents and pesticides. The gene (opa) encoding an OPAA was cloned from the chromosomal DNA of Alteromonas haloplanktis ATCC 23821. The nucleotide sequence of the 1.7 -kb DNA fragment contained the opa gene (1.3 kb) and its flanking region. We report structural and functional similarity of OPAAs from A. haloplanktis and Alteromonas sp JD6.5 with the enzyme prolidase that hydrolyzes dipeptides with a prolyl residue in the carboxyl-terminal position. These results corroborate the earlier conclusion that the OPAA is a type of X-Pro dipeptidase, and that X-Pro could be the native substrate for such an enzyme in Alteromonas cells.

Amino Acid Sequence↗
PubMed1997

Cloning of a Ca(2+)-ATPase gene and the role of cytosolic Ca2+ in the gibberellin-dependent signaling pathway in aleurone cells.

The ultimate goal of this investigation was to identify intermediary steps in the gibberellin (GA)-dependent signaling pathway in rice aleurone cells. By using a differential display approach, a number of putative GA-responsive genes were isolated. One of them, a GA-responsive Ca(2+)-ATPase gene, was identified and partially characterized. A genomic clone and a cDNA clone were isolated and sequenced. The deduced amino acid sequence showed that this protein resembles an endoplasmic reticulum membrane Ca(2+)-ATPase. In a transient assay in rice aleurone cells, expression of the introduced Ca(2+)-ATPase cDNA bypassed the GA requirement for stimulating the expression of a major target gene, the alpha-amylase c gene (Osamy-c). This result suggests that GA-dependent expression of this Ca(2+)-ATPase gene (OsCa-atpase) plays an important role in the GA-dependent signal-transduction pathway. To investigate the possible involvement of other proteins and genes that may affect the intracellular Ca2+ level, compounds which can block different putative steps in the signal-transduction pathway were introduced into rice aleurone cells, and then the level of the OsCa-atpase transcript or the Osamy-c transcript was monitored. In the presence of GA, the rice Ca(2+)-ATPase and the Ca2+ channels appeared to co-regulate the local concentration of cytosolic Ca2+. The release of Ca2+ from the internal stores to the cytoplasm was presumably initiated by inositol-1,4,5-triphosphate which reached a peak level within 25 min after GA induction. As a second messenger, Ca2+ binds to calmodulin (CaM), and the Ca2+/CaM complex regulates the cytosolic Ca2+ by affecting expression of the OsCa-atpase. Finally, a working model is proposed for the GA-dependent signaling pathway in aleurone cells.

Amino Acid Sequence↗
PubMed1997

Two missense mutations of H type alpha(1,2)fucosyltransferase gene (FUT1) responsible for para-Bombay phenotype.

BACKGROUND AND OBJECTIVES: Rare individuals (Bombay and para-Bombay phenotypes) fail to express the A, B and H antigens on erythrocyte membranes because of a lack in the H gene (FUT1)-encoded alpha(1,2)fucosyltransferase activity. In this study, we have found a para-Bombay individual (Bmh) who expressed B and H antigens in saliva but not on red blood cells. The FUT1 alleles of this person contained two single base changes (T460C and G1042A) in the coding region relative to the wild type allele. These substitutions may result in changes in two amino acid residues (Y154H and E348K). MATERIALS AND METHODS: Since the T460C and G1042A mutations destroy endonuclease RsaI and AvaI sites, respectively, we tested for these mutations using PCR-RFLP. RESULTS: Our findings indicated that this para-Bombay person was homozygous for the T460C and G1042A mutations, and that neither of these mutations was found in 136 randomly selected Japanese individuals. The measurement of the alpha(1,2)fucosyltransferase activity after transient expression of the FUT1 alleles in COS-7 cells indicated that the H-deficient allele-encoded enzyme had no detectable activity. Moreover, transfection by chimera FUT1 allele contains only the T460C mutation, or only the G1042A mutation, and yielded 1.0 or 9.3%, respectively, of the activities compared to transfection by the wild type allele. CONCLUSIONS: These results suggest that the two mutations in combination are responsible for the inactivation of the FUT1-encoded enzyme activity.

ABO Blood-Group System↗
PubMed1997

New spirostanol glycosides from Anemarrhena asphodeloides.

Two new spirostanol saponins, named anemarsaponin F (2b) and G (4b), along with six known spirostanol saponins were obtained from the rhizomes of Anemarrhena asphodeloides Bunge. On the basis of spectral analyses and chemical evidence, the structures of 2b and 4b were established as neogitogenin 3-O-beta-glucopyranosyl-(1-->2) [beta-xylopyranosyl-(1-->3)]-beta-glucopyranosyl (1-->4)-beta-galactopyranoside) and lilagenin 3-O-beta-glucopyranosyl-(1-->2)-[beta-xylopyranosyl-(1-->3)]-beta- glucopyranosyl-(1-->4)-beta-galactopyranoside, respectively.

Carbohydrate Conformation↗
PubMed1997

Drug-induced vasodilation: the effects of sodium nitroprusside, hydralazine, and cromakalin on the rabbit carotid artery: in vitro and in vivo study.

Extreme arterial and venous constructions are common problems in microvascular surgery, often leading to tissue injury and flap failure. The ideal pharmacologic tool to counteract ischemia should exert its action both locally and distally in the microcirculation of the flap. In this study, the vascular properties of sodium nitroprusside, hydralazine, and cromakalin were evaluated and compared in in vitro and in vivo models in the rabbit carotid artery. In the in vitro study, 20 rings from the rabbit carotid artery were bathed in Krebs-Ringers solution, stretched progressively to an optimal tension of 3.7 to 4.2 gm, and their isometric contractile activity was measured. The specimens were precontracted with norepinephrine (1 microM) and a dose-response curve was established by adding cumulatively either sodium nitroprusside (n = 7), cromokalin (n = 7), or hydralazine (n = 7) at increasing concentrations. In the in vivo study, microvascular anastomoses were performed bilaterally in the rabbit carotid artery in 19 animals using 9-0 nylon suture and standard microsurgical techniques. In each animal, one side was treated with heparinized sodium chloride, and served as control. The other side was treated blindly with the topical application of 1 ml of either sodium nitroprusside (10 mg/ml, n = 5), hydralazine (20 mg/ml, n = 5), or cromakalin (25 mg/ml, n = 4), during and after the anastomoses. Blood-flow changes in the vessels were continuously monitored with the transonic Doppler applied to both carotid arteries for 60 min after the procedure. Sodium nitroprusside and cromakalin elicited a concentration-dependent relaxation of norepinephrine-precontracted carotid artery rings in vitro. Sodium nitroprusside was significantly more effective than cromakalin in inducing relaxation. Hydralazine elicited a biphasic response, with low concentrations (1.5 x 10(-5) to 1.5 x 10(-3) M) potentiating the norepinephrine-induced contraction, and high concentrations relieving this contraction. Microsurgical anastomosis in the rabbit carotid artery-produced a significant decrease of blood flow through the vessel as measured by the transonic Doppler for 30 min. Topical application of heparinized saline did not significantly change the blood flow after the microvascular anastomosis. Topical application of sodium nitroprusside and cromakalin significantly increased the blood flow in the vessel after the anastomosis; however, the topical hydralazine did not significantly alter blood flow, but demonstrated a trend toward increased flow values. The data support the conclusion that sodium nitroprusside and cromakalin could be used to relieve vascular constriction. It is suggested that further studies on the clinical use of these drugs in microsurgery is warranted.

Animals↗
PubMed1997

DNA vaccination as anti-human immunodeficiency virus immunotherapy in infected chimpanzees.

The role of the immune response in controlling human immunodeficiency virus type 1 (HIV-1) replication is controversial. Immunotherapeutic strategies that have the ability to broaden immune responses might play a role in slowing disease progression. DNA immunization was studied as immunotherapy in infected chimpanzees. Two HIV-1-infected chimpanzees were vaccinated with DNA plasmid vaccines, one with plasmid pCMN160, which expresses the envelope glycoprotein of HIV-1MN and rev, and the other with a control plasmid. The chimpanzee immunized with pCMN160 demonstrated enhanced humoral responses. Virus load was monitored. Virus load in the chimpanzee receiving pCMN160 decreased at week 20 and has remained at background levels. The control chimpanzee was subsequently vaccinated with pCMN160. After immunization, the antibody responses increased and, as in the first animal, the virus load decreased. These results indicate the potential of the immune response to have a direct impact on HIV-1 replication in chimpanzees.

Amino Acid Sequence↗
PubMed1997

Molecular analyses of human immunodeficiency virus type 1 V3 region quasispecies derived from plasma and peripheral blood mononuclear cells of the first long-term-nonprogressing mother and child pair.

Molecular analyses were done for the V3 region quasispecies of human immunodeficiency virus type 1 (HIV-1) strains from plasma and peripheral blood mononuclear cells of the first HIV-1-infected long-term-nonprogressing mother-child pair whose members have survived for >13 years with stable CD4 T cell counts. There was a predominance of lower V3 loop charge and the absence of genotypic changes that are critical in phenotypic determination and tropism during HIV-1 infection. The intrahost genetic diversity between HIV-1 strains from the mother-child pair compared with HIV-1 strains from slow and rapid progressors suggested that a high genetic heterogeneity in HIV-1 strains from this HIV-1-infected long-term-nonprogressing mother and child pair was directly proportional to the length of their immunocompetent period.

Amino Acid Sequence↗
PubMed1997

Costimulation with ultraviolet B and interleukin-1 alpha dramatically increase tumor necrosis factor-alpha production in human dermal fibroblasts.

Ultraviolet light, particularly in wavelengths of 290-320 nm (UVB), is known to induce cytokine synthesis in the skin. Cytokines act in a cascade fashion and can have synergistic or antagonistic actions on regulation of other cytokines. In this study, we sought to determine whether cotreatment with UVB and interleukin-1 alpha (IL-1 alpha) induces tumor necrosis factor-alpha (TNF-alpha) production synergistically by human dermal fibroblasts. UVB irradiation (200 J/m2) or IL-1 alpha (10 ng/ml) independently induced small amount of TNF-alpha (< 25 pg/ml) from human dermal fibroblasts. However, combined treatments with UBV and IL-1 alpha induced 30-40-fold higher levels of TNF-alpha (750 pg/ml) than with either UVB of IL-1 alpha treatment alone. This synergy was also seen with mRNA expression. Maximum synergistic effect was observed when IL-1 alpha was added immediately after irradiation. Considering the fact that UVB is capable of causing release of IL-1 alpha from human keratinocytes and approximately 10% of incident UVB penetrates to the level of dermal fibroblasts, our results suggest that UVB may act in a cascade fashion to induce inflammation by initial release of keratinocyte IL-1 alpha, which then synergizes with UVB on human dermal fibroblasts to significantly increase TNF-alpha production.

Cells, Cultured↗
PubMed1997

Effects of interferons on the production of interleukin-6 and interleukin-8 in human keratinocytes.

Interferons (IFNs) originally described for antiviral activity have been reported to have pleiotropic effects, including the ability to induce interleukin-6 (IL-6) and IL-8 production in several cell types. IL-6 and IL-8 are proinflammatory cytokines and are known to be produced by a wide variety of cells, including human keratinocytes. In the present study, we sought to examine the effects of IFNs on IL-6 and IL-8 production from human keratinocytes. IFN-gamma (10-50 ng/ml) induced IL-6 and IL-8 production dose dependently, but no induction of IL-6 or IL-8 was observed with either IFN-alpha or IFN-beta. Because cytokines often work in a cascade fashion and keratinocytes are a source of primary cytokines, IL-1 alpha, and tumor necrosis factor-alpha (TNF-alpha), we examined whether combined treatment with IFN-gamma and these primary cytokines, IL-1 alpha and TNF-alpha, had a synergistic effect on the production of IL-6 and IL-8. Combined treatment with IFN-gamma and IL-1 alpha induced 6-fold to 7-fold higher levels of IL-6 than IL-1 alpha alone. Combined treatment with IFN-gamma and TNF-alpha induced 11-fold to 12-fold higher levels of IL-6 than TNF-alpha alone. The same treatment induced 3-fold to 4-fold higher levels of IL-8 in both cases. These results suggest that IFN-gamma is a positive regulator for the production of IL-6 and IL-8 from human keratinocytes and likely has an augmentative effect on skin inflammation.

Cells, Cultured↗
PubMed1997

The expression and modulation of IFN-alpha and IFN-beta in human keratinocytes.

In addition to leukocytes and fibroblasts, the classic sources of human interferons (IFN), many other human cells are now known to be capable of producing IFN. Keratinocytes (KC) are abundant in the skin and provide the first line of defense against viruses and other noxious agents. Human KC are a potent source of cytokines and were implicated as forming IFN-like protein(s). We have investigated whether KC form IFN. We found that culture supernatants from unstimulated human KC did not contain detectable amounts of IFN-alpha or IFN-beta. However, those from KC activated with the potent IFN inducer, polyriboinosinic:polriboycytidylic acid (poly rI:rC), had appreciable antiviral activity, which studies with neutralizing sera showed to be caused by IFN-beta. In ELISA tests, we detected IFN-beta protein in the supernatants but not IFN-alpha protein. Nevertheless, reverse transcription PCR showed that both IFN-alpha and IFN-beta mRNA were upregulated in poly rI:rC-treated KC. The levels of these mRNA were also increased in KC exposed to ultraviolet B (UVB) irradiation, interleukin-1alpha (IL-1alpha), tumor necrosis factor-alpha (TNF-alpha), or lipopolysaccharide (LPS). These results show that IFN-beta is among the cytokines secreted from human KC and, together with IFN-alpha, may have a role in host defense mechanisms in the skin.

Antiviral Agents↗
PubMed1997

Absence of natural killer cells during murine pregnancy is associated with reproductive compromise in TgE26 mice.

Strategies of cell depletion were pursued to extend understanding of the functions of natural killer (NK) cell-like large granulated lymphocytes found in the rodent uterus during pregnancy. Repeated infusions of antibody to Ly-49G2, a surface marker thought to be expressed by the progenitor forms of these cells, removed Ly-49G2+ cells from the virgin but not the pregnant uterus. Large granulated uterine lymphocytes also differentiated during pregnancy in transgenic mice that carried a deletion in the IL-2 gene. This cell population was absent in two strains of mice, p56lck-/lck-.IL-2Rbeta-/IL-2Rbeta- and TgE26. Implantation sites in both of these strains had histopathological anomalies in the zone of decidualization. In TgE26 mice, a sudden onset of fetal loss began at Day 10 of gestation. Fetal death was associated with progressive changes in the maternal uterine arterioles, suggestive of localized arteriosclerosis associated with hypertension. TgE26 females carried immune-competent fetuses to term, apparently through preventive or compensatory mechanisms that may modify the uterine vasculature after the onset of vascular pathology. These studies are the first to suggest a vital role for large granulated lymphocytes in the promotion of fetal survival and pregnancy success.

Animals↗