[International expert consensus on gene therapy for hereditary hearing loss: based on clinical trials].
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
X Y Chen
Publications and source records attributed to X Y Chen.
A TiO2/AC composite photocatalyst with high activity and easy separation prepared by a hydrothermal method.
In the present work, a TiO2/activated carbon (AC) photocatalyst with high activity and easy separation was prepared using a hydrothermal method. Phenol, methyl orange (MO) and Cr(VI) were used as target pollutants to test the activity and decantability. SEM, XRD, FTIR, diffuse reflectance spectra (UV/DRS) and N2 adsorption isotherms were used to characterize the crystalline and electronic structure. Results show that the AC composite has a significant effect on the TiO2 activity. With suitable AC content, the TiO2/xAC catalysts prepared were much more active. The TiO2/5AC catalyst exhibited easy separation and less deactivation after several runs, and was less sensitive to pH changes. UV/DRS revealed that no electronic bandgap changes in TiO2 occurred on addition of the AC. SEM and XRD results suggest that better TiO2 distribution can be achieved when an optimal AC content is used. A Ti-O-C bond was formed and a slight conjugation effect appeared between the AC bulk and TiO2. The advantages of the obtained TiO2/5AC catalyst revealed its great practical potential in wastewater treatment.
Azo Compounds↗
Activated carbon with excellent chromium(VI) adsorption performance prepared by acid-base surface modification.
In the present work, activated carbon (AC) with excellent Cr(VI) adsorption performance especially at low concentrations was prepared by an acid-base surface modification method. Raw activated carbon (AC(0)) was first oxidized in boiling HNO(3) (AC(1)), then treated with a mixture of NaOH and NaCl (AC(2)). Batch equilibrium and continuous column adsorption were conducted to evaluate the adsorption performance. Boehm titration, elemental analysis, and N(2)/77K adsorption isotherm methods were used to characterize the surface properties and pore structure of modified ACs. The results revealed that the modified AC exhibited excellent Cr(VI) adsorption performance in terms of adsorption capacity and adsorption rate: AC(2)>AC(1)>AC(0). Modification caused S(BET) to decrease and the total number of surface oxygen acidic groups to increase. HNO(3) oxidization produced positive acid groups, and subsequently NaOH treatment replaced H(+) of surface acid groups by Na(+), and the acidity of AC decreased. The main cause of higher Cr(VI) adsorption capacity and rate for AC(2) was the presence of more oxygen surface acidic groups and suitable surface acidity. HNO(3)-NaOH modification shows potential for the preparation of high quality AC for the effective removal of low concentrations of Cr(VI).
Adsorption↗
Development of a multifunctional and efficient conjugal plasmid for use in Streptomyces spp.
A plasmid, pGB112, has recently been developed to transfer DNA from Escherichia coli to Streptomyces spp via conjugation. This technique made use of (A) E. coli replicon, (B) ampicillin (amp) resistance gene for selection in E. coli and thiostrepton (tsr) resistance gene for selection in Streptomyces, (C) a fragment of SCP2* replicon, (D) a 2.6 kb fragment of tra-cassette which consists of pIJ101 transfer gene (tra) and two ermE promoters, (E) a 0.8 kb fragment of oriT of (IncP) RK2. The results showed that this plasmid was able to transfer plasmid DNA from E. coli to Streptomyces coelicolor via conjugation, and that it could also transfer DNA between Streptomyces strains. Since this plasmid has both pBR322 and SCP2* replicons, it may provide a novel and useful method for genetic operation in E. coli and Streptomyces.
Conjugation, Genetic↗
[Effects of antiviral effects of agents and prognosis of chronic hepatitis B.].
BACKGROUND: To analyze the effects of difference antiviral agents and the effects of the treatments on long-term prognosis. METHODS: Retrospective research method was applied. RESULTS: About 40% of the patients were treated with interferon or lamivudine. After the treatment, in lamivudine group, the negative rate of HBV DNA was the highest. In the interferon group, the sero conversion rates of HBeAg/HBeAb were 22.9%. In the antiviral treatment patients, the disease progression and the occurrence of cirrhosis and liver cancer were much lower than those of the control groups. The mortality of cirrhosis and liver cancer in the HBeAg/HBeAb sero converted group was much lower than that of the group without HBeAg/HBeAb sero conversion groups (P less than 0.05). CONCLUSION: The antiviral effects of interferon and lamivudine were better than those of the other drug groups. The antiviral drugs could relieve the disease progression and reduce the mortality of cirrhosis and liver cancer.
Antiviral Agents↗
Analysis of energy level structure and excited-state dynamics in a Sm 3+ complex with soft-donor ligands: Sm(Et2Dtc)3(bipy).
Using both laser-excited fluorescence and optical absorption methods, we have determined 57 crystal-field (CF) energy levels of Sm 3+ in crystals of Sm(Et2Dtc)3(bipy). The analysis of the energy levels is based on a model Hamiltonian consisting of both free-ion and CF terms. The CF modeling of the experimental energy levels yielded physically reasonable Hamiltonian parameters with a final rms deviation of 17.3 cm(-1). In comparison with Sm 3+ in other hosts, the CF splitting of Sm 3+ in the lattice of Sm(Et2Dtc)3(bipy) is rather weak. The observed fluorescence decay of the 4G(5/2) manifold is single-exponential, with a lifetime of 24.5 mus, indicating only one site of Sm3+ in the lattice. According to the Judd-Ofelt theory, values of three intensity parameters were obtained (Omega(2,4,6) = 1.57, 2.65, and 3.65, in units of 10(-20) cm(-1)). The calculated branching ratios for transitions from the 4G(5/2) manifold are in agreement with experimental values. The calculated radiative lifetime of the 4G(5/2) manifold is 3.24 ms, and the corresponding fluorescence quantum efficiency is only 0.75%. Efficient multiphonon relaxation processes induced by the localized high-frequency vibrational modes in the bipyridyl group may lead to the extremely low quantum efficiency observed. The thermal line broadening and shifts of the 4G(5/2)(1) --> 6F(1/2) transition were observed and fitted very well by the McCumber-Sturge equations with an assumption of Raman phonon scattering processes as the leading relaxation mechanism. The Debye temperature for this crystal is predicted to be 350 K.
Journal Article↗
Chinese medicinal herbs for influenza.
BACKGROUND: Influenza is an acute respiratory communicable disease which can cause high morbidity and mortality in an epidemic. Traditional Chinese medicinal herbs following a particular theory may be a potential medicine of choice. OBJECTIVES: The objective of this review was to assess the therapeutic effect and adverse reaction of Traditional Chinese medicinal herbs in treating uncomplicated influenza. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2004); MEDLINE (January 1966 to October 2004); EMBASE (January 1988 to October 2004); CBM (Chinese Biomedical Database) (January 1980 to December 2003); and the Chinese Cochrane Center's Controlled Trials Register (up to December 2003). We also searched Current Controlled Trials (www.controlled-trials.com) and the National Research Register (http://www.update-software.com/National/) for ongoing trials and reference lists of articles. We wrote to researchers in the field, or authors of studies evaluated in the review for more information. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing traditional Chinese medicinal herbs with placebo, or various other Chinese medicinal herbs, or with other current regimes normally used in care or comparing drugs with herbal preparations to simple drugs in treating defined uncomplicated influenza patients. DATA COLLECTION AND ANALYSIS: At least two reviewers extracted data and assessed trial quality. MAIN RESULTS: Eleven studies with the number of participants ranged from 52 to 479. In total 2,088 participants were included in the review. As the interventions of the included studies were different from each other and most of the studies were of low quality, we did not perform a summary meta-analysis. Some of the studies showed positive results favouring Traditional Chinese medicinal herb treatment compared to antiviral or antipyretic-analgesic drugs or the combination of them. Only three studies mentioned adverse reactions but no detailed data were acquired in the included studies. Eleven studies with the number of participants ranged from 52 to 479, 2,088 in total were included. As the interventions of the included studies were different from each other and most of the studies were of low quality, we failed to perform a summary meta-analysis. Some of the studies showed positive results favouring Traditional Chinese medicinal herb treatment compared to antiviral or antipyretic-analgesic drugs or the combination of them. Only three studies mentioned adverse reactions but no detailed data was acquired in the included studies. AUTHORS' CONCLUSIONS: The small number of included studies and participants, as well as the low quality of most studies, made the evidence far from conclusive for clinical decision making, although traditional Chinese medicinal herbs as a whole seem to be comparatively or more effective compared to different chemical drugs. A certain herbal preparation could not be recommended for there was not enough evidence. More high quality randomised controlled trials (RCTs) with similar interventions are required to strengthen the evidence for the efficacy and safety of certain herbal preparation.
Drugs, Chinese Herbal↗
Structural identification of bitespiramycin metabolites in rat: a single oral dose study.
Bitespiramycin is a macrolide antibiotic consisting of a mixture of some nine spiramycin ester derivatives. It has a similar spectrum of antibiotic activity to that of spiramycin but has superior pharmacokinetic properties. In this study, a rapid and facile LC/ESI-MSn method was applied to study the metabolism of bitespiramycin in rat following a single oral dose (80 mg kg-1). Concentrations of parent drug constituents and metabolites were determined in plasma, urine, feces and bile. Concentrations of parent drug constituents and metabolites in plasma were very low. In urine, feces and bile, parent drug constituents and 38 metabolites were identified on the basis of their chromatographic and mass spectrometric properties. The identity of 17 metabolites was confirmed by comparison with reference substances. The principal metabolites were the corresponding spiramycins formed by hydrolysis of the 4''-(3-methylbutanoate) groups. Other important metabolic pathways were: hydrolytic loss of the forosamine and mycarose sugars; aldehyde reduction; cysteine conjugation of the aldehyde group; and hydrolysis of the lactone ring. Products formed by lactone ring opening were found only in urine, and those formed by aldehyde reduction were found only in feces. Aldehyde reduction and hydrolytic loss of forosamine represent novel biotransformation pathways for spiramycin derivatives.
Administration, Oral↗
Comparison of subcooled liquid vapor pressures of polychlorinated dibenzo-p-dioxins and dibenzofurans predicted by QSPR and GC-RI methods.
Subcooled liquid vapor pressures (P(L)) are of great importance for assessing the persistent behavior of organic pollutants. As P(L) cannot be determined by direct experiments, it is of interest to develop and evaluate various predictive methods. In the current study, gas chromatography retention index (GC-RI) and quantitative structure-property relationship (QSPR) methods were used to develop predictive models for P(L) of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The model development was based on P(L) values converted from consistent experimental solid vapor pressures (P(S)). The P(L) values predicted by the two methods are highly consistent with each other, and in-between sets of values predicted by others. Since the QSPR method can be regarded as independent of experiments, and can be used to interpret intermolecular interactions that govern the magnitude of P(L), it may be superior to the GC-RI method.
Benzofurans↗
Up-regulation of macrophage migration inhibitory factor in infants with acute neonatal necrotizing enterocolitis.
AIMS: To investigate the role of macrophage migration inhibitory factor (MIF) and its downstream cytokine cascade in necrotizing enterocolitis (NEC). METHODS AND RESULTS: The expression of MIF mRNA and protein in NEC guts was assayed by in situ hybridization and immunohistochemistry, respectively. Concentrations of MIF, interleukin (IL)-6 and IL-8 in the serum and in the supernatant of macrophage cultures were examined by ELISA. Increased expression of MIF mRNA and protein was observed in the NEC guts, mainly in the infiltrating macrophages in the mucosa and submucosal layers. Up-regulation of MIF was associated with the accumulation of macrophages and T cells. In addition, serum levels of MIF, IL-6 and IL-8 in NEC patients during the acute stage of the disease were significantly increased. The expression of MIF decreased both locally and systemically after the disease was resolved. MIF was also found to increase the secretion of IL-6 and IL-8 by macrophages isolated from healthy individuals in vitro in NEC. CONCLUSIONS: MIF acts by stimulating macrophage production of IL-6 and IL-8. This further aggravates the inflammatory process by increasing the infiltration of neutrophils and activating inflammatory cells. The results of this study suggest that MIF plays an important role in the pathogenesis of NEC and may serve as a target for therapeutic intervention in NEC.
Acute Disease↗
Synthesis of hydrophilic polymer-grafted ultrafine inorganic oxide particles in protic media at ambient temperature via atom transfer radical polymerization: use of an electrostatically adsorbed polyelectrolytic macroinitiator.
A new approach for the surface grafting of polymer chains to colloidal substrates is described. A cationic macroinitiator has been designed for the surface polymerization of a wide range ofhydrophilic methacrylates from ultrafine inorganic oxide sols by atom transfer radical polymerization in protic media at ambient temperature. One advantage of this approach is that it allows one-pot syntheses: the macroinitiator is adsorbed onto the sol, followed by an in situ polymerization. Nonionic, cationic, and betaine monomers can be polymerized directly by this protocol, with reasonably high conversions being obtained, as judged by 1H NMR spectroscopy. Anionic monomers such as sodium 4-styrenesulfonate cannot be polymerized directly due to incompatibility problems with the cationic macroinitiator-coated sol. However, hydroxylated monomers such as glycerol monomethacrylate can be surface-polymerized and then converted to anionic polyelectrolytes by reaction with succinic anhydride under mild conditions. This derivatization was confirmed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopic analysis. Thermogravimetry was used to assess the degree of polymer grafting. Higher target degrees of polymerization led to increased grafted polymer loadings, as expected. Particle morphologies and relative degrees of dispersion in aqueous solution were assessed by transmission electron microscopy and dynamic light scattering, respectively. Surface characterization of the polymer-grafted sols was achieved by X-ray photoelectron spectroscopy and aqueous electrophoresis measurements. Most of the data reported in this study concern surface polymerizations from ultrafine silica sols, but some preliminary data for ultrafine tin(IV) oxide sols are also presented. Since most surfaces are negatively charged, this cationic macroinitiator approach can, in principle, be extended to include a wide range of sols, latexes, and planar substrates without requiring a separate surface functionalization step.
Journal Article↗
Optimal cutoff point of glutamate decarboxylase antibody titers in differentiating two subtypes of adult-onset latent autoimmune diabetes.
The optimal cutoff point of glutamate decarboxylase antibody (GAD-Ab) titers for differentiating two latent autoimmune diabetes (LADA) subtypes remains unclear. One hundred and forty-five GAD-Ab-positive patients screened from phenotypic type 2 diabetes were diagnosed as LADA. The clinical features were compared among LADA patients with different GAD-Ab titers. The receiver-operating characteristic (ROC) curve was used to evaluate the diagnostic value of GAD-Ab titers and to define the optimal cutoff point. The heterogeneity of clinical features in LADA could be discriminated by five GAD-Ab titers, with maximal differences at the titer of 175 U/mL. The ROC curve analysis showed that the optimal cutoff point for discriminating two LADA subtypes was at the titer of 175 U/mL, with sensitivity and specificity of 54.5% and 92.1%, respectively. These findings demonstrated that the two clinically distinct subtypes of LADA can be optimally discriminated by the GAD-Ab titers.
Adult↗
A novel metabolic pathway of morphine: formation of morphine glucosides in cancer patients.
AIMS: To characterize directly the conjugated metabolites of morphine in urine samples of cancer patients. METHODS: Urine samples from the patients were treated by solid-phase extraction method and chromatographed using three high-performance liquid chromatography systems. Conjugated metabolites were directly detected with liquid chromatographic/ion trap mass spectrometric (LC/MSn) technique by selected ion monitoring, full scan MS/MS and MS3 modes. RESULTS: Six conjugated metabolites including two new metabolites M5 and M6 were found. Morphine-3-glucuronide (M-3-G) and morphine-6-glucuronide (M-6-G) were identified by comparing their l.c. retention times and multistage mass spectra with those of the reference substances. Two novel metabolites, morphine-3-glucoside and morphine-6-glucoside, as well as normorphine glucuronides were identified by comparing their mass fragment patterns and l.c. retention times with those of M-3-G and M-6-G. Hydrolysis of urine samples with beta-glucosidase and beta-glucuronidase provided further evidence of the metabolites M5 and M6 as morphine glucosides. The excretion amounts of morphine conjugates in urines were in the order of morphine glucuronides, morphine glucosides and normorphine glucuronides. CONCLUSIONS: In the present study, the applications of l.c. separation and multistage mass spectra have permitted the direct identification of conjugated metabolites of morphine. To our knowledge, this is the first report about O-linked glucosides of morphine at 3-aromatic and 6-aliphatic hydroxyl groups.
Aged↗
LC-MS-MS analysis of 2-pyridylacetic acid, a major metabolite of betahistine: application to a pharmacokinetic study in healthy volunteers.
1. A sensitive liquid chromatographic-tandem mas spectrometric assay was developed and validated to determine the major metabolite of betahistine, 2-pyridylacetic acid, in human plasma. 2. The analyte was extracted from plasma samples by liquid-liquid extraction and analysed using liquid chromatography-tandem mass spectrometry with an electrospray ionization interface. The method has a lower limit of quantitation of 1 ng ml(-1) fir a 0.5-ml plasma aliquot. The intra- and interday precision (relative standard deviation), calculated from quality control (QC) samples, was less than 10%. Accuracy as determined from QC samples was within +/-7%. 3. The validated method was successfully applied to a pharmacokinetic study of betahistine in healthy volunteers. After oral administration of a single dose of 24 mg betahistine mesylate to 20 healthy Chinese male volunteers, Cmax was 339.4 ng ml(-1) (range 77.3-776.4 ng ml(-1)). The t(1/2) was 5.2 h (range 2.0(-1)-11.4h). The AUC(0-t) obtained was 1153.5 ng ml(-1) h (range 278.5-3150.8 ng ml(-1)). The disposition of the metabolite exhibited a marked interindividual variation. 4. The plasma concentrations of the parent drug were less than 0.5 ng ml(-1), suggesting that it undergoes almost complete first-pass metabolism. The reported two active metabolites were not detected in the plasma of any volunteer. Although there is no evidence that the major metabolite has pharmacological activity, the clinical importance of 2-pyridylacetic acid in humans should be reinvestigated.
Acetates↗
A study on the friction of a self-correction ultrasonic stepping motor.
An experiment has been carried out to investigate the self-correction function of a self-correction ultrasonic stepping motor. When a slider (rotor) is placed on a vibrating beam (stator), it will stay at a stable equilibrium position. If the slider is slightly moved off the equilibrium position, a restoring force will urge the slider back towards its equilibrium position. The experimental result shows that the position of the maximum restoring force on the slider differs from that predicted by using the linear theory. Study found that when a quadratic form is assumed for the dynamic friction coefficient, the theoretical and experimental results are in good agreement.
Journal Article↗
Helicobacter pylori associated gastric diseases and lymphoid tissue hyperplasia in gastric antral mucosa.
AIM: To investigate the relation between Helicobacter pylori associated gastroduodenal diseases and lymphoid tissue hyperplasia in the antral mucosa and to pursue its evolution after eradication of H pylori. METHODS: Gastric antral biopsy specimens were obtained from 438 patients with H pylori positive gastroduodenal diseases (185 chronic gastritis, 69 gastric ulcer, and 184 duodenal ulcer) and 50 H pylori negative healthy controls. Lymphoid follicles and aggregates were counted and other pathological features were scored according to the updated Sydney system for classification of chronic gastritis. After a course of anti-H pylori treatment, biopsy specimens were obtained at four to six weeks, 12 months, and 24 months in the chronic gastritis patient group. RESULTS: The total prevalence of lymphoid follicles and aggregates in the biopsies was 79.9% (350 of 438; 95% confidence intervals (CI), 0.76 to 0.84). The prevalence and density of lymphoid follicles and aggregates were significantly different in the various gastroduodenal diseases. The highest prevalence (89.9%; 95% CI, 0.83 to 0.97) and density (0.82) of lymphoid follicles and aggregates occurred in patients with gastric ulcers. The lowest prevalence of lymphoid follicles and aggregates was found in patients with chronic gastritis (74.6%; 95% CI, 0.68 to 0.81), and the lowest density of lymphoid follicles and aggregates (0.56) was seen in patients with duodenal ulcers. The prevalence and density of lymphoid follicles and aggregates correlated strongly with the activity and severity of gastric antral mucosal inflammation. The eradication of H pylori resulted in a decrease in the prevalence and density of lymphoid follicles and aggregates. CONCLUSION: The prevalence and density of lymphoid follicles and aggregates in gastric antral mucosal biopsies correlated closely with H pylori infection.
Adolescent↗
Effects of chronic nerve cuff and intramuscular electrodes on rat triceps surae motor units.
In order to assess the long-term effects of implanted electrodes on motor unit properties, we studied triceps surae (TS) motor units in rats implanted for 3-10 months with a tibial nerve cuff electrode for H-reflex elicitation and intramuscular electrodes for recording TS electromyographic activity. Motor units with sag from implanted rats displayed greater tetanic force than those from unimplanted rats. Motor units without sag had shorter twitch contraction times. This disrupted the relationship between sag and contraction time that was always present in unimplanted rats. These differences were consistent with a small degree of muscle denervation and subsequent reinnervation. Further analyses ascribed this effect to the nerve cuff rather than to the intramuscular electrodes. Comparable changes in motor unit properties may occur in humans with implanted nerve cuffs.
Action Potentials↗
Ricin A-chain inhibitors resembling the oxacarbenium ion transition state.
Ricin toxin A-chain (RTA) is expressed by the castor bean plant and is among the most potent mammalian toxins. Upon activation in the cytosol, RTA depurinates a single adenine from position 4324 of rat 28S ribosomal RNA, causing inactivation of ribosomes by preventing the binding of elongation factors. Kinetic isotope effect studies have established that RTA operates via a D(N)*A(N) mechanism involving an oxacarbenium ion intermediate with bound adenine [Chen, X.-Y., Berti, P. J., and Schramm, V. L. (2000) J. Am. Chem. Soc. 122, 1609-1617]. On the basis of this information, stem-loop RNA molecules were chemically synthesized, incorporating structural features of the oxacarbenium ion-like transition state. A 10-base RNA stem-loop incorporating (1S)-1-(9-deazaadenin-9-yl)-1,4-dideoxy-1,4-imino-D-ribitol at the depurination site binds four times better (0.57 microM) than the 10-base RNA stem-loop with adenosine at the depurination site (2.2 microM). A 10-base RNA stem-loop with 1,2-dideoxyribitol [(2R,3S)-2-(hydroxymethyl)-3-hydroxytetrahydrofuran] at the depurination site binds with a Kd of 3.2 microM and tightens to 0.75 microM in the presence of 9-deazaadenine. A similar RNA stem-loop with 1,4-dideoxy-1,4-imino-D-ribitol at the depurination site binds with a K(d) of 1.3 microM and improves to 0.65 micro;M with 9-deazaadenine added. When (3S,4R)-4-hydroxy-3-(hydroxymethyl)pyrrolidine was incorporated at the depurination site of a 14-base RNA stem-loop, the Kd was 0.48 microM. Addition of 9-deazaadenine tightens the binding to 0.10 microM whereas added adenine increases the affinity to 12 nM. The results of this study are consistent with the unusual dissociative D(N)*A(N) mechanism determined for RTA. Knowledge of this intermediate has led to the design and synthesis of the highest affinity inhibitor reported for the catalytic site of RTA.
Adenine↗