Biomedical subjects

X D Yang

Publications and source records attributed to X D Yang.

At least 19 recordsLinked to original sources

PubMed2006

Verapamil modulates LPS-induced cytokine production via inhibition of NF-kappa B activation in the liver.

OBJECTIVE: To investigate the effect of verapamil on Lipopolysaccharide (LPS)-induced cytokines [tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-10 (IL-10)] and nuclear factor kappa B (NF-kappa B) in the liver. METHODS AND MATERIALS: Adult male Sprague-Dawley rats were randomly divided into seven groups of eight rats each: control rats treated with saline (0.9 % NaCl); rats treated with saline and then challenged intraperitoneally with LPS (10 mg/kg); rats treated intraperitoneally with different levels of verapamil (1, 2.5, 5, 10 mg/kg) and then challenged with LPS (10 mg/kg); and rats treated only with verapamil (10 mg/kg). TNF-alpha, IL-6, IL-10 and NF-kappa B in the liver tissues were investigated as well as the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) one hour after LPS injection. RESULTS: LPS alone stimulated production of TNF-alpha, IL-6 and IL-10, and activated NF-kappa B in the liver. Pretreatment with verapamil before LPS challenge reduced acute liver injury, down-regulated production of LPS-induced pro-inflammatory cytokines (TNF-alpha and IL-6), up-regulated production of anti-inflammatory cytokines (IL-10) and inhibited NF-kappa B activation in the liver in a dose-dependent manner. CONCLUSION: Verapamil can attenuate acute liver injury by down-regulating the production of TNF-alpha and IL-6 and up-regulating IL-10 in the liver, possibly via inhibition of NF-kappa B.

Animals↗

PubMed2004

Double-peak emission of hot electrons generated by femtosecond laser interaction with solid targets.

Double-peak emission of hot electrons has been observed in the interaction of a 60-fs, 125-mJ, 800-nm, p-polarized laser pulse with Al targets. One peak in the specular direction is due to the reflected laser light, which excites a plasma wave to accelerate electrons. The other peak, which is more consistent with theories of Phys. Plasmas 6, 2855 (1999)] and Phys. Rev. Lett 82, 743 (1999)], is produced by the resonance absorption at approximately 15 degrees from the target normal.

Journal Article↗

PubMed2003

Fully human anti-interleukin 8 antibody inhibits tumor growth in orthotopic bladder cancer xenografts via down-regulation of matrix metalloproteases and nuclear factor-kappaB.

PURPOSE: We previously demonstrated that overexpression of interleukin 8 (IL-8) in human transitional cell carcinoma (TCC) resulted in increased tumorigenicity and metastasis. This increase in tumor growth and metastasis can be attributed to the up-regulation in the expression and activity of the metalloproteinases MMP-2 and MMP-9. EXPERIMENTAL DESIGN: To investigate whether targeting IL-8 with a fully human anti-IL-8 antibody (ABX-IL8) could be a potential therapeutic strategy for controlling TCC growth, we studied its effects on TCC growth in vitro and in an in vivo mouse model. Human TCC cell lines 253J B-V and UM UC3 (high IL-8 producers), 253J (low IL-8), and 253J transfected with the IL-8 gene (high producer) were used. RESULTS: ABX-IL8 had no effect on TCC cell proliferation in vitro. However, in the orthotopic nude mouse model, after 4 weeks of treatment (100 micro g/week, i.p.), a significant decrease in tumor growth of both cell lines was observed. IL-8 blockade by ABX-IL8 significantly inhibited the expression, activity, and transcription of MMP-2 and MMP-9, resulting in decreased invasion through reconstituted basement membrane in vitro. The down-regulation of MMP-2 and MMP-9 in these cells could be explained by the modulation of nuclear factor-kappaB expression and transcriptional activity by ABX-IL8. CONCLUSIONS: Our data point to the potential use of ABX-IL8 as a modality to treat bladder cancer and other solid tumors, either alone or in combination with conventional chemotherapy or other antitumor agents.

Animals↗

PubMed2001

Analytical methodologies for aluminium speciation in environmental and biological samples--a review.

It is recognized that aluminium (Al) is a potential environmental hazard. Acidic deposition has been linked to increased Al concentrations in natural waters. Elevated levels of Al might have serious consequences for biological communities. Of particular interest is the speciation of Al in aquatic environments, because Al toxicity depends on its forms and concentrations. In this paper, advances in analytical methodologies for Al speciation in environmental and biological samples during the past five years are reviewed. Concerns about the specific problems of Al speciation and highlights of some important methods are elucidated in sections devoted to hybrid techniques (HPLC or FPLC coupled with ET-AAS, ICP-AES, or ICP-MS), flow-injection analysis (FIA), nuclear magnetic resonance (27Al NMR), electrochemical analysis, and computer simulation. More than 130 references are cited.

Aluminum↗

PubMed2001

Xanthones from the stems of Securidaca inappendiculata.

From the stems of Securidaca inappendiculata, securixanthones A (1,3,7-trihydroxy-2,8-dimethoxyxanthone) and B (3,7-dimethoxy-4-hydroxyxanthone) along with ten known xanthones were isolated. Their structures were elucidated by analysis chemical and spectroscopic evidence, and the chemotaxonomic significance of these findings are also discussed.

Magnetic Resonance Spectroscopy↗

PubMed2001

Development of ABX-EGF, a fully human anti-EGF receptor monoclonal antibody, for cancer therapy.

Overexpression of epidermal growth factor receptor (EGFr) has been demonstrated on many human tumors, and the increase in receptor expression levels has been linked with a poor clinical prognosis. Blocking the interaction of EGFr and the growth factors could lead to the arrest of tumor growth and possibly result in tumor cell death. To this end, using XenoMouse technology, ABX-EGF, a human IgG2 monoclonal antibody (mAb) specific to human EGFr, has been generated. ABX-EGF binds EGFr with high affinity (5x10(-11) M), blocks the binding of both EGF and transforming growth factor-alpha (TGF-alpha) to various EGFr-expressing human carcinoma cell lines, and inhibits EGF-dependent tumor cell activation, including EGFr tyrosine phosphorylation, increased extracellular acidification rate, and cell proliferation. In vivo ABX-EGF prevents completely the formation of human epidermoid carcinoma A431 xenografts in athymic mice. More importantly, administration of ABX-EGF without concomitant chemotherapy results in complete eradication of established tumors. No tumor recurrence was observed for more than 8 months following the last antibody injection, further indicating complete tumor cell elimination by the antibody. Inhibition of human pancreatic, renal, breast and prostate tumor xenografts which express different levels of EGFr by ABX-EGF was also achieved. Tumor expressing more than 17000 EGFr molecules per cell showed significant growth inhibition when treated with ABX-EGF. ABX-EGF had no effect on EGFr-negative tumors. The potency of ABX-EGF in eradicating well-established tumors without concomitant chemotherapy indicates its potential as a monotherapeutic agent for treatment of multiple EGFr-expressing human solid tumors, including those where no effective chemotherapy is available. Utilization of mAbs directed to growth factor receptors as cancer therapeutics has been validated recently by the tumor responses obtained from clinical trials with Herceptin, the humanized anti-HER2 antibody, in patients with HER2 overexpressing metastatic breast cancer. Being a fully human antibody, ABX-EGF is anticipated to exhibit a long serum half-life and minimal immunogenicity with repeated administration, even in immunocompetent patients. These results demonstrate the potent anti-tumor activity of ABX-EGF and its therapeutic potential for the treatment of multiple human solid tumors that overexpress EGFr.

Animals↗

PubMed2001

[Organic acid constituents from the stem of Securidaca inappendiculata Hassk].

OBJECTIVE: To investigate the organic acid constituents from the stem of Securidaca inappendiculata. METHOD: Column chromatographic techniques were used to isolate and purify the constituents. The structures were elucidated by spectra analysis. RESULT: Five compounds were isolated and identified as ferulic acid (I), cinnamic acid(II), palmitic acid(III), salicylic acid(IV) and benzoic acid(V). CONCLUSION: Compounds I-IV were isolated from the plant for the first time.

Cinnamates↗

PubMed2001

[Determination of annonaceous acetogenins in annonaceae plants by HPLC].

AIM: To develop a method for analysis of antitumor annonaceous acetogenins in Annonaceae plants by HPLC. METHODS: Squamostatin-B (1), squamocin (2) and annonin-VI (3) were used as standard substances. Chromatography column was a Rp-18; the mobile phase was methanol-water (90:10); the flow rate was 1.0 mL.min-1 and the detecting wavelength was 220 nm. RESULTS: A linear range was obtained from 2.3 to 13.8 micrograms with a good correlation. The recoveries of (1), (2) and (3) were 100.3%, 100.3% and 100.0%, respectively. CONCLUSION: This method was developed for the analysis of acetogenins by HPLC for the first time. The method is rapid, accurate and suitable for the analysis of the antitumor acetogenins in Annonaceae plants.

4-Butyrolactone↗

PubMed2000

[Studies on chemical constituents of Erythrina arborescens Roxb].

OBJECTIVE: To study the chemical constitutes in Erythrina arborescens. METHOD: Various chromatographic techniques were used to isolate and purify the constituents. The structures were elucidated by spectral analysis and chemical evidence. RESULT: Six compounds were isolated from the plant and identified as alpinumisoflavone, wighteone, daidzein, genistein, vittadinoside and stigmasterol. CONCLUSION: All these compounds were isolated from the plant for the first time.

Erythrina↗

PubMed2000

[Purification of follicle-stimulating hormone by radial-flow chromatography].

By comparing the purification results of radial-flow chromatography with conventional chromatography, a new purification process of follicle-stimulating hormone (FSH) from crude sample of human menopausal gonadotrophin has been developed. The results showed that the specific activity, activity recovery, and purification factor of FSH purified by radial-flow chromatography were higher than those by conventional chromatography in large scale. The specific activity of FSH purified was 180 IU/mg protein, activity recovery 56%, purification factor 150. The purified product meets the quality requirement of the Standard of Chinese Pharmacopoeia.

Chromatography, Ion Exchange↗

PubMed1999

Eradication of established tumors by a fully human monoclonal antibody to the epidermal growth factor receptor without concomitant chemotherapy.

A fully human IgG2kappa monoclonal antibody (MAb), E7.6.3, specific to the human epidermal growth factor (EGF) receptor (EGFr) was generated from human antibody-producing XenoMouse strains engineered to be deficient in mouse antibody production and to contain the majority of the human antibody gene repertoire on megabase-sized fragments from the human heavy and kappa light chain loci. The E7.6.3 MAb exhibits high affinity (KD = 5 x 10(-11) M) to the receptor, blocks completely the binding of both EGF and transforming growth factor alpha (TGF-a) to various EGFr-expressing human carcinoma cell lines, and abolishes EGF-dependent cell activation, including EGFr tyrosine phosphorylation, increased extracellular acidification rate, and cell proliferation. The antibody (0.2 mg i.p. twice a week for 3 weeks) prevents completely the formation of human epidermoid carcinoma A431 xenografts in athymic mice. More importantly, the administration of E7.6.3 without concomitant chemotherapy results in complete eradication of established tumors as large as 1.2 cm3. Tumor eradication of A431 xenografts was achieved in nearly all of the mice treated with total E7.6.3 doses as low as 3 mg, administered over the course of 3 weeks, and a total dose of 0.6 mg led to tumor elimination in 65% of the mice. No tumor recurrence was observed for more than 8 months after the last antibody injection, which further indicated complete tumor cell elimination by the antibody. The potency of E7.6.3 in eradicating well-established tumors without concomitant chemotherapy indicates its potential as a monotherapeutic agent for the treatment of multiple EGFr-expressing human solid tumors, including those for which no effective chemotherapy is available. Being a fully human antibody, E7.6.3 is expected to exhibit minimal immunogenicity and a longer half-life as compared with mouse or mouse-derivatized MAbs, thus allowing repeated antibody administration, including in immunocompetent patients. These results suggest E7.6.3 as a good candidate for assessing the full therapeutic potential of anti-EGFr antibody in the therapy of multiple patient populations with EGFr-expressing solid tumors.

Animals↗

PubMed1999

Fully human anti-interleukin-8 monoclonal antibodies: potential therapeutics for the treatment of inflammatory disease states.

Interleukin-8 (IL-8) is a potent chemotactic cytokine implicated in the pathogenesis of a number of inflammatory disease states. Agents that block the binding of IL-8 to its receptor have been shown to block inflammation in animal models of disease. This suggests that drugs specifically targeting IL-8 may prove efficacious in treating multiple human diseases. To this end, we developed a panel of fully human anti-IL-8 monoclonal antibodies (mAbs). These human antibodies were generated from XenoMouse strains, mice created by introducing megabase-size unrearranged human immunoglobulin heavy and kappa light chain loci into a mouse genome in which the corresponding endogenous loci have been inactivated. From the panel of more than 50 mAbs, two antibodies, K4.3 and K2.2, were further characterized and evaluated for their specificity, productivity, affinity, and biological activity. Both K4.3 and K2.2 bind human IL-8 with high affinity (Kd of K4.3 = 2.1x10(10) M; Kd of K2.2 = 2.5x10(-10) M). In vitro, in addition to blocking IL-8 binding to human neutrophils, K4.3 and K2.2 blocked a number of IL-8-dependent cellular functions including neutrophil activation, up-regulation of the cell adhesion receptor CD11b/CD18, and neutrophil chemotaxis, suggesting that the fully human anti-IL-8 mAbs derived from XenoMouse strains are potent anti-inflammatory agents. This was further supported by in vivo studies in which K4.3 and K2.2 significantly inhibited IL-8-induced skin inflammation in rabbits. A pharmacokinetic study in Cynomolgus monkeys demonstrated that the alpha phase half-life is 9.4 h and the beta phase 10.9 days, typical of human mAbs in monkeys. These data support advancing a fully human anti-IL-8 mAb into clinical trials to treat inflammatory diseases.

Animals↗

PubMed1999

Maturation and developmental stage-related changes in fetal globin gene expression are reproduced in transiently transfected primary adult human erythroblasts.

A novel system is described, which uses transfection of primary human erythroblasts for the study of gene regulation in differentiating human red cells. This system includes a protocol for liquid culture of erythroid progenitors, which reproduces developmental differences in globin gene expression found between adult and cord blood as well as the maturation-related changes in fetal globin levels observed in adult cells. Reporter constructs driven by globin gene promoters were electroporated into adult and cord blood-derived erythroblasts at different time points during culture. Both the developmental stage and maturation-related differences in endogenous fetal and adult globin gene expression could be reproduced by the transiently transfected reporter constructs. Transfection of primary human erythroblasts during differentiation provides a previously unavailable opportunity to study dynamic aspects of erythropoiesis.

Adult↗

PubMed1998

The roles of alpha 4-integrins in the development of insulin-dependent diabetes mellitus.

Lymphocyte/endothelial adhesion followed by transendothelial migration is a key event in the development of organ-specific autoimmunity. Selective interactions of cell surface AM regulate lymphocyte migration under normal as well as pathologic inflammatory conditions. NOD mice are an ideal model for investigating the roles of AM in regulation of lymphocyte migration to target organs in autoimmune diseases such as IDDM. Both in vitro and in vivo studies in NOD mice strongly suggest that the mucosal (alpha 4 beta 7/MAdCAM-1) adhesion system and alpha 4-integrin/VCAM-1 appear to be prominent pathways for insulitis development. In contrast, alpha 4-mediated interactions in NOD inflamed salivary and lacrimal gland and in the inflamed CNS of rodents with EAE seem to be dominated by alpha 4-integrins and VCAM-1. The fact that blocking alpha 4-integrin pathways in NOD mice leads to successful interruption of the diabetogenic process suggests that AM provide a potential therapeutic target for human IDDM. Further studies on IDDM patients will prove helpful for understanding IDDM pathogenesis and in providing a basis for designing AM-based therapeutic approaches.

Animals↗

PubMed1998

Relationship between cellular uptake rate and chemical behavior of diammine/diaminocyclohexane platinum (II) complexes with oxygen-ligating anionic groups.

The uptake kinetics of the platinum (II) complexes of the formula Pt(NH3)2X, Pt(dach)X by human erythrocyte in the plasma isotonic buffer was studied. The results showed that across-membrane transport of all the platinum complexes studied follows a first-order kinetic process. The uptake rate constants decrease with the change of oxygen-ligating anionic group in the sequence: sulfato > selenato > anion of squaric acid > oxalato > anion of demethylcantharic acid > malonato and increase with increasing lipophilicity of carrier group. The relationship between uptake rate and reactivity of these complexes was established. The stereochemistry of dach isomers was shown without effect on the reactivity and the sequence.

Actins↗

PubMed1998

Prevention of diabetes in NOD mice by a mutated I-Ab transgene.

Susceptibility to the human autoimmune disease IDDM is strongly associated with those haplotypes of the major histocompatibility complex (MHC) carrying DQB1 alleles that do not encode aspartic acid at codon 57. Similarly, in a spontaneous animal model of this disease, the NOD mouse, the genes of the MHC play an important role in the development of diabetes. The DQB1 homolog in NOD mice, I-Ab(g7), encodes a histidine at codon 56 and a serine at codon 57, while all other known I-Ab alleles encode proline and aspartic acid, respectively, at these positions. We therefore mutated the NOD I-Ab allele to encode proline at position 56 and aspartic acid at position 57 and introduced this allele onto the NOD genetic background to study the effect of these substitutions on susceptibility to diabetes. No transgenic mice developed diabetes by 8 months of age, and transgenic mice had markedly reduced lymphocytic infiltration in the pancreas compared with nontransgenic littermates. Furthermore, splenocytes from transgenic mice failed to proliferate or secrete gamma-interferon in response to a panel of beta-cell autoantigens, although the mice did produce beta-cell specific antibodies. Interestingly, the proportion of IgG1 and IgE relative to IgG2a comprising these autoantibodies was much greater in transgenic mice compared with nontransgenic control mice. Finally, T-cells from transgenic mice inhibited the adoptive transfer of diabetes to irradiated recipients. This inhibition was partially reversed by treatment of the recipients with a combination of anti-interleukin (IL)-4 and anti-IL-10 monoclonal antibodies. Thus, a transgenic class II MHC allele encoding aspartic acid at B57 prevents diabetes, in part, by promoting the production of IL-4 and IL-10, which interfere with the effector phase of the diabetic process.

Animals↗

PubMed1998

Induction of GAD65-specific regulatory T-cells inhibits ongoing autoimmune diabetes in nonobese diabetic mice.

IDDM is a T-cell-mediated autoimmune disease in which the insulin-producing beta-cells are destroyed. The disease process is complex, involving the recognition of several beta-cell autoantigens. One of these, GAD65, appears to have a critical and not fully defined role in IDDM in humans and in the NOD mouse. We provide evidence that an ongoing diabetogenic response in NOD mice can be suppressed after intravenous administration of GAD65, but not by other beta-cell autoantigens. Furthermore, suppression of the diabetogenic response is mediated by the induction of GAD65-specific CD4+ regulatory T-cells. Finally, cytokine analysis indicates that these CD4+ regulatory T-cells have a T-helper 2 phenotype.

Adoptive Transfer↗

PubMed1997

Chronic tumor necrosis factor alters T cell responses by attenuating T cell receptor signaling.

Repeated injections of adult mice with recombinant murine TNF prolong the survival of NZB/W F1 mice, and suppress type I insulin-dependent diabetes mellitus (IDDM) in non-obese diabetic (NOD) mice. To determine whether repeated TNF injections suppress T cell function in adult mice, we studied the responses of influenza hemagglutinin-specific T cells derived from T cell receptor (HNT-TCR) transgenic mice. Treatment of adult mice with murine TNF for 3 wk suppressed a broad range of T cell responses, including proliferation and cytokine production. Furthermore, T cell responses of HNT-TCR transgenic mice also expressing the human TNF-globin transgene were markedly reduced compared to HNT-TCR single transgenic littermates, indicating that sustained p55 TNF-R signaling is sufficient to suppress T cell function in vivo. Using a model of chronic TNF exposure in vitro, we demonstrate that (a) chronic TNF effects are dose and time dependent, (b) TNF suppresses the responses of both Th1 and Th2 T helper subsets, (c) the suppressive effects of endogenous TNF produced in T cell cultures could be reversed with neutralizing monoclonal antibodies to TNF, and (d) prolonged TNF exposure attenuates T cell receptor signaling. The finding that anti-TNF treatment in vivo enhances T cell proliferative responses and cytokine production provides evidence for a novel regulatory effect of TNF on T cells in healthy laboratory mice. These effects are more pronounced in chronic inflammatory disease. In addition, our data provide a mechanism through which prolonged TNF exposure suppresses disease in animal models of autoimmunity.

Animals↗