Biomedical subjects

Xuan Zhang

Publications and source records attributed to Xuan Zhang.

102 records · Page 6Linked to original sources

PubMed2003

[Methylprednisolone and cyclophosphamide pulse therapy of severe systemic lupus erythematosus in children].

OBJECTIVE: To study the effect of methylprednisolone (MP) and cyclophosphamide (CPA) intermittent intravenous pulse therapy and the clinical prognosis in children with severe juvenile onset systemic lupus erythematosus (JOSLE). METHODS: Thirty patients with JOSLE, diagnosed by clinical, laboratory or renal histological examinations, were enrolled in this study. Of the 30 patients, 27 were females and 3 were males, the mean age was (12 +/- 3) years, and 20 of the 22 patients who had undergone initial therapy had LN, and the clinical courses before being involved in the study were 3 to 12 months in nine patients. Twenty-three of the 30 patients had clinical manifestations of renal damages, of whom 4 patients were proven by initial renal biopsy to have WHO type IV, 2 had type II,1 had type V and 1 had type III, and 7 patients had one or more manifestations of central nervous system, including chorea, seizures, cerebrovascular accident (CVA) and organic brain syndrome (OBS), simultaneously, 9 patients had nervous system symptoms without the clinical manifestations of renal damages, 3 patients had lupus crisis, 7 patients did not have any manifestations of renal or neurological damages. According to the protocol of the therapy, the patients were divided into 3 groups: group A (n = 18) patients were treated with MP plus CPA intermittent intravenous pulse for children with lupus nephritis, and with or without neuropsychiatric lupus erythematosus (NPLE), group B (n = 7) with pulsed doses of MP, followed by prednisone and tripterygium wilfordii hook f(T(whf)) for patients without renal or central nerves system damage, and group C (n = 5) with prednisone alone for patients with LN determined by clinical and laboratory features. The effects of those regimes and the clinical prognosis were observed. RESULTS: On short-term follow-up, the SLEDAI-2K (by weight of the renal damage) showed significant difference between group A and group B, but there was no significant difference at the 9th months of the therapy. The long-term follow-up lasted in average for (37.2 +/- 24.8) months. Nineteen patients were followed up for more than 18 months. At the end of follow-up, the mean age was 14 to 19 years. There was no difference on the effect of both group A and group B, and no frequent infections were seen, ANAs were negative and SLEDAI-2K = 0-point in two patients of each group 12 months after discontinuation of the therapy. Four patients in group C died within 18 months. CONCLUSION: The immunosuppressive regimen MP + CPA in patients with severe JOSLE and MP + prednisone + T(whf) in patients without major organs damage were superior to the regimen of prednisone alone.

Adolescent↗

PubMed2003

[Secondary structure of insulin encapsulated within liposomes].

AIM: To determine the secondary structure of insulin encapsulated within liposomes. METHODS: The secondary structure of insulin, mixture of insulin with liposomes (I) and insulin liposomes (II) were determined by Fourier transform infrared (FTIR) spectroscopy. RESULTS: The figures of secondary structure of insulin, sample I and II were similar. The results showed that the amount of alpha-helix and beta-sheet of insulin, sample I and II had little difference, from 36.09% (insulin) to 31.68% (sample I) and 31.45% (sample II), and from 47.83% (insulin) to 53.29% (I) and 51.36% (II), respectively. The results showed that the insulin of sample I and II did not insert in liposomes membrane, only adsorbed or extendedon the surface of the liposomes. CONCLUSION: The secondary structure of insulin encapsulated within liposomes has not been destroyed and still remain the original state.

Drug Carriers↗

PubMed2002

Effects of testosterone and 17-beta-estradiol on TNF-alpha-induced E-selectin and VCAM-1 expression in endothelial cells. Analysis of the underlying receptor pathways.

This study investigated the effects of testosterone and 17-beta-estradiol on tumor necrosis factor-alpha (TNF-alpha)-induced endothelial expression of E-selectin and vascular cell adhesion molecule-1 (VCAM-1) and the potential roles of hormone receptors involved in these actions. Human umbilical vein endothelial cells (HUVEC) were stimulated with TNF-alpha in the presence or absence of testosterone or 17-beta-estradiol, and the expression of E-selectin and VCAM-1 was investigated. As shown by Western blot analysis, co-administration with testosterone or 17-beta-estradiol increased the expression of E-selectin and VCAM-1 induced by TNF-alpha at 6 h and 3 h, respectively. Similarly, RT-PCR analysis revealed a significant increase in the amount of mRNA for E-selectin and VCAM-1 after co-administration with testosterone or 17-beta-estradiol in TNF-alpha-stimulated HUVEC. The presence of mRNA and proteins for androgen receptor and estrogen receptor alpha in HUVEC was verified by RT-PCR and Western blot. Flow cytometric analysis showed that preincubation with androgen receptor antagonist cyproterone and estrogen receptor antagonist tamoxifen completely abrogated the upregulating effects of testosterone and 17-beta-estradiol on TNF-alpha-induced E-selectin and VCAM-1 expression, respectively. Expression of TNF receptors in TNF-alpha-stimulated HUVEC was not influenced by testosterone and 17-beta-estradiol. The data indicate that both testosterone and 17-beta-estradiol increase TNF-alpha-induced E-selectin and VCAM-1 expression in endothelial cells via a receptor-mediated system, and expression of TNF receptors are not changed in these actions. The implications of these results for the facilitory effects of both sex hormones on immune reactions are discussed.

Androgen Receptor Antagonists↗

PubMed2002

Reactions of trivacant Wells-Dawson heteropolytungstates. Ionic strength and Jahn-Teller effects on formation in multi-iron complexes.

Reaction of alpha-P(2)W(15)O(56)(12-) and Fe(III) in a saturated NaCl solution produces a trisubstituted Wells-Dawson structure with three low-valent metals, alpha-(Fe(III)Cl)(2)(Fe(III)OH(2))P(2)W(15)O(59)(11-) (1). Dissolution of this species into 1 M NaBr (Br(-) is non-coordinating) gives the triaquated species alpha-(Fe(III)OH(2))(3)P(2)W(15)O(59)(9-) (2). Ionic strength values of 1 M or greater are necessary to avoid decomposition of 1 or 2 to the conventional sandwich-type complex, alpha beta beta alpha-(Fe(III)OH(2))(2)Fe(III)(2)(P(2)W(15)O(56))(2)(12-) (3). If the pH is greater than 5, a new triferric sandwich, alpha alpha beta alpha-(NaOH(2))(Fe(III)OH(2))Fe(III)(2)(P(2)W(15)O(56))(2)(14-) (4), forms rather than 3. Like the previously reported Wells-Dawson-derived sandwich-type structures with three metals in the central unit ([TM(II)Fe(III)(2)(P(2)W(15)O(56))(P(2)TM(II)(2)W(13)O(52))],(16-) TM = Cu, Co), this complex has a central alpha-junction and a central beta-junction. Thermal studies suggest that 4 is more stable than 3 over a wide range of temperatures and pH values. The intrinsic Jahn-Teller distortion of d-electron-containing metal ions incorporated into the external sites of the central multi-metal unit impacts the stoichiometry of their incorporation (with a consequent change in the inter-POM-unit connectivity, where POM = polyoxometalate). Reaction of non-distorting Ni(II) with the diferric lacunary sandwich-type POM alpha alpha alpha alpha-(NaOH(2))(2)Fe(III)(2)(P(2)W(15)O(56))(2)(16-) (5) produces alpha beta beta alpha-(Ni(II)OH(2))(2)Fe(III)(2)(P(2)W(15)O(56))(2)(14-) (6), a Wells-Dawson sandwich-type structure with two Ni(II) and two Fe(III) in the central unit. All structures are characterized by (31)P NMR, IR, UV-vis, magnetic susceptibility, and X-ray crystallography. Complexes 4 and 6 are highly selective and effective catalysts for the H(2)O(2)-based epoxidation of alkenes.

Alkenes↗

PubMed2002

Photocatalytic degradation of aqueous 4-chlorophenol by silica-immobilized polyoxometalates.

The degradation of 4-chlorophenol with near-UV light by silica-immobilized polyoxometalate (POM-in-SiO2) catalysts has been studied. The silica-immobilized Na6W7O24 (SW7), H4W1032 (SW10), H3PW12O40 (SPW12), and H6P2W18O62 (SP2W18) were prepared by means of the sol-gel hydrothermal technique through the hydrolysis of tetraethoxysilane in aqueous solution of the corresponding polyoxometalate, respectively. The degradation of 4-chlorophenol was monitored by measuring Cl- and CO2 concentrations and analyzing reaction intermediates by GC/MS analysis. During irradiation, 4-chlorophenol first dechlorinated to form hydroquinone and p-benzoquinone, and then these intermediates further mineralized to form CO2 and H2O. The degree to which 4-chlorophenol was mineralized by photocatalytic oxidation was investigated. Results indicate less than 15% for SW7 but nearly complete mineralization for SW10 after 60 min of photoirradiation. The present studies suggest that POM-in-SiO2 catalysts may be a novel type of photocatalyts for the purification of the environmentally chlorophenol-contaminated water.

Catalysis↗

PubMed2002

Expression of gelatinases and their tissue inhibitors in rat corpus luteum during pregnancy and postpartum.

Extensive tissue remodeling occurs in the corpus luteum (CL) during both formation and luteolysis. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are believed to play pivotal roles in these processes. In the present study, to evaluate the potential roles of matrix degrading proteases in luteal development and regression, we examined gelatinases and TIMP-1, -2, -3 mRNA expressions, as well as gelatinase activity in rat CL during pregnancy and postpartum using Northern blot, in situ hybridization, and gelatin zymography, respectively. The results showed that MMP-2 mRNA was only expressed at the early stages of pregnancy; TIMP-2 mRNA was highly expressed at the early and late pregnancy and day 1 postpartum, but could not be detected during the mid-phase of pregnancy; TIMP-3 mRNA expression was abundant during early pregnancy and peaked at day 7, but was absent from other time points examined. MMP-9 and TIMP-1 mRNAs in rat CL were below detectable level in the current study. Furthermore, the active MMP-2 was only present during the early stages of pregnancy, and no MMP-9 activity was observed in the zymogram. Taken together, our results suggest that MMP-2 and TIMP-3 may have functional roles in rat luteal formation, while TIMP-2 may be implicated in both formation and regression of the pregnant CL.

Animals↗

PubMed2002

Expression and localization of RAP250 mRNA in rat ovary: possible implications in follicular development and ovulation.

The expression levels of nuclear receptor coregulators in specific tissue compartments and cells are thought to influence the expression of hormone-responsive genes involved in metabolism, development, and reproduction. RAP250 is a novel nuclear receptor coactivator highly expressed in brain and reproductive organs. To investigate the possible involvement of RAP250 in tissue-specific regulation of ovarian function, untreated immature, pregnant mare's serum gonadotropin luteinizing hormone (PMSG-LH)-primed, cycling, and pregnant rat models were used to study the localization and expression of RAP250 mRNA in rat ovary by in situ hybridization (ISH) and reverse transcriptase polymerase chain reaction (RT-PCR). The results showed that RAP250 mRNA was primarily localized to granulosa cells of healthy follicles in immature, cycling, and pregnant rats and increased during PMSG-induced follicular development. In the preovulatory and ovulatory follicles from the LH-primed rats of 48-h post-PMSG administration, the signals for RAP250 mRNA increased further and remained high until early luteal formation. Only a subset of corpora lutea during diestrus 1, diestrus 2, and initiation of pregnancy was weakly positive, and atretic follicles were largely negative. The RT-PCR results confirmed the presence of RAP250 mRNA in the rat ovary and strengthen the data from ISH. These findings suggest that RAP250 may play potential roles in follicular development and ovulation.

Animals↗

PubMed2002

[Interaction between insulin with liposome].

AIM: To study the characteristics of the interaction between insulin and liposome. METHODS: The interaction between insulin and liposome was studied by fluorescence spectra and microcalorimetry methods. The sample of insulin liposome interaction after separation by supper-centrifugalization or gel filtration was determined by fluorescence and HPLC. RESULTS: The results indicate that there was only little increase in fluorescence intensity and no blue shift of peak in fluorescence spectrum. Fluorescence quenching experiments with NaI and acrylamide as quenchers showed that the KSVs (the slope of Strm-Volmer equation) of insulin were more similar to that with added liposome, indicating low interaction between insulin with liposome. The microcalorimetric results indicate that the heat released during the mixture of liposome with insulin, was 1.98 kcal.mol-1, suggesting that the reaction belongs to weak reaction. The quantity of insulin in the insulin-liposome mixture sample after separation by ultracentrifuge or by Sephadex G-75 determined by HPLC, the combination percent was only 0.2%, indicating low interaction between insulin and liposome. CONCLUSION: The interaction between insulin and liposome was weak.

Chemistry, Pharmaceutical↗

PubMed2002

Clinical and pathological manifestations of patients with antineutrophil cytoplasmic autoantibodies directed against proteinase 3 or myeloperoxidase.

OBJECTIVE: To compare the clinical and pathological manifestations of patients with antineutrophil cytoplasmic autoantibodies (ANCA) directed against proteinase 3 (anti-PR3) or myeloperoxidase (anti-MPO). METHODS: One hundred and forty patients with ANCA were detected for anti-PR3 and anti-MPO by ELISA. The clinical features at presentation, histopathological characteristics and outcome of all patients who were tested positive for anti-PR3 or anti-MPO were analysed. RESULTS: In anti-PR3 group (n = 21), 16 cases (76.2%) had systemic vasculitis, in which Wegener's granulomatosis prevailed (13 cases, 61.9%). In anti-MPO group (n = 31), 19 cases (61.3%) were diagnosed as systemic vasculitis and 12 cases (38.7%) as microscopic angiitis. For vasculitic patients with anti-PR3 and anti-MPO, the disease duration at diagnosis was 9.6 +/- 2.0 m and 4.4 +/- 0.9 m respectively, P < 0.05; vasculitis activity index (BVAS) and mean number of affected organ were 22.5 +/- 2.1, 5.0 +/- 0.4 and 25.1 +/- 1.7, 4.8 +/- 0.4 respectively, P > 0.05; upper respiratory tract, eye and joint involvements were 11(68.8%), 7(43.8%), 11(68.8%) and 7(36.8%), 2(10.5%), 5(26.3%) respectively, P < 0.05. Although there was no statistical difference in renal involvement between these two groups, patients with serum creatine > 500 micromol/L were more commonly seen in anti-MPO group than in anti-PR3 group, which were 8(42.1%) and 2(12.5%) respectively, P < 0.05. Ten relapses were seen in anti-PR3 group and only 2 in anti-MPO group, but the acute mortality rate in anti-MPO group (5/19, 27.4%) was much higher than that in anti-PR3 group (1/16, 6.3%). CONCLUSIONS: Anti-PR3 and anti-MPO occurred mainly in systemic vasculitis. A large divergence was seen in the disease spectrum between patients with anti-PR3 and those with anti-MPO. In particular, upper respiratory tract, eye and joint involvements, granuloma formation and relapse were more prominent in anti-PR3 patients. By contrast, the anti-MPO patients had a more acute disease onset, more rapid progressive renal involvement and a higher acute mortality rate.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed1997

Multiiron Polyoxoanions. Synthesis, Characterization, X-ray Crystal Structure, and Catalytic H(2)O(2)-Based Alkene Oxidation by [(n-C(4)H(9))(4)N](6)[Fe(III)(4)(H(2)O)(2)(PW(9)O(34))(2)].

A tetranuclear ferric Keggin sandwich-type heteropolyanion has been synthesized by the reaction of the lacunary species Delta-Na(8)H[PW(9)O(34)] with FeCl(2) followed by O(2) oxidation in nonaqueous media. The structure of [(n-C(4)H(9))(4)N](6)[Fe(III)(4)(H(2)O)(2)(PW(9)O(34))(2)].4CH(3)CN.2CH(2)Cl(2).2H(2)O (TBA-1) was determined by single-crystal X-ray diffraction (orthorhombic, Pbca; R = 0.0693 for 14 963 reflections with F(o) > 4sigma(F(o))). The compound was further characterized by infrared and UV-visible spectroscopy, electrochemistry, magnetic susceptibility, FAB mass spectrometry (FAB-MS), and elemental analyses. Five lines of evidence are consistent with the Fe(III)(4) oxidation state: (i) valence sum calculations from the X-ray structure (ca. 2.86 +/- 0.07 per Fe); (ii) the rest potential from cyclic voltammetry; (iii) charge balance requirements; (iv) titration with Ce(IV)(SO(4))(2); and (v) oxidation by O(2). In contrast to the tetranuclear ferric Wells-Dawson-derived sandwich complex, [Fe(III)(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](12-), TBA-1 can only be prepared from a ferrous precursor. TBA-1 is a catalyst for the oxidation of hydrocarbons with H(2)O(2). The selectivity for epoxide is low (10-50%). Unlike most other transition-metal-substituted polyoxometalates (TMSPs), TBA-1 is very stable under turnover conditions in aqueous H(2)O(2) (no detectable changes in the IR or NMR spectra after 48 h). The rate of H(2)O(2) disproportionation catalyzed by TBA-1 is relatively low (the ratio of rates, disproportionation to oxidation, is ca. 3:2).

Journal Article↗

PubMedDate not supplied

Preparation and characterization of insulin nanoparticles employing chitosan and poly(methylmethacrylate/methylmethacrylic acid) copolymer.

As most of polypeptides are marginally stable, a mild formulation procedure would be beneficial for the activities of these drugs. The objective of the present study was to develop a novel pH-sensitive nanoparticle system that was suitable for entrapment of hydrophilic insulin but without affecting its conformation. Chitosan was incorporated as a positively charged material, and one of the three poly(methylmethacrylate/methylmethacrylic acid) copolymers, consisting of Eudragit L100-55, L100, and S100, was used as a negatively charged polymer for preparation of three insulin nanoparticles, respectively. Three nanoparticles obtained were spherical. The mean diameters were in the range from 200 nm to 250 nm, and the entrapment efficiencies, from 50% to 70%. The surface analysis indicated that insulin was evenly distributed in the nanoparticles. Polymer ratio of chitosan to Eudragit was the factor which influenced the nanoparticles significantly. Characterization results showed that the electrostatic interactions existed, thus providing a mild formulation procedure which did not affect the chemical integrity and the conformation of insulin. In vitro release studies revealed that all three types of the nanoparticles exhibited a pH-dependant characteristic. The modeling data indicated that the release kinetics of insulin was nonlinear, and during the release process, the nanoparticles showed a polynomial swelling. On overall estimation, the insulin chitosan-Eudragit L100-55 nanoparticles may be better for the oral delivery. This new pH-sensitive nanoparticle formulation using chitosan and Eudragit L100-55 polymer may provide a useful approach for entrapment of hydrophilic polypeptides without affecting their conformation.

Chitosan↗

PubMedDate not supplied

Thymopentin-loaded pH-sensitive chitosan nanoparticles for oral administration: preparation, characterization, and pharmacodynamics.

Thymopentin, a potent immunomodulating drug, was incorporated into pH-sensitive chitosan nanoparticles prepared by ionic gelation of chitosan with tripolyphosphate anions and then coated with Eudragit S100 to improve the stability and the oral bioavailability. Nanoparticles particle size and zeta potential were measured by photo correction spectroscopy and laser Dopper anemometry. Its morphology was examined by environment scan electron microscope. The encapsulation efficiency and the release in vitro were determined by HPLC. Enzymatic stabilization was expressed by the enzymatic degradation of aminopeptidase. Biological activity of TP5 loaded in nanoparticles was assayed by lymphocyte proliferation test in vitro and the immune function (CD4+/CD8+) of irradiated rat in vivo. The results obtained demonstrated that the average sizes of pH-sensitive chitosan nanoparticles were 175.6 +/- 17 nm, the zeta potential was 28.44 +/- 0.5 mV and the encapsulation efficiency was 76.70 +/- 2.6%. The cumulative release percentages of thymopentin from the pH-sensitive nanoparticles were 24.65%, 41.01%, and 81.44% incubated in different medium, 0.1 N HCl, pH 5.0 PBS, and pH 7.4 PBS, respectively. The pH-sensitive chitosan nanoparticles could efficiently protect TP5 from enzymatic degradation and prolong the degradation half-time of TP5 from 1.5 min to 15 min. It was demonstrated from the lymphocyte proliferation test that the nanoparticle-encapsulated TP5 still kept its biological activity. In immunosuppression rats, the lowered T-lymphocyte subsets values were significantly increased and the raised CD4+/CD8+ ratio was evidently reduced. These results indicated that pH-sensitive chitosan nanoparticles may be used as the vector in oral drug delivery system for TP5.

Adjuvants, Immunologic↗