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Xiaodong Huang

Publications and source records attributed to Xiaodong Huang.

At least 19 recordsLinked to original sources
PubMed2006

Synthesis and monoamine transporter binding properties of 2,3-cyclo analogues of 3beta-(4'-aminophenyl)-2beta-tropanemethanol.

A series of cyclo-3beta-(4-aminophenyl)-2beta-tropanemethanol analogues (5a-m) possessing varying linker groups between the 2- and 3-position on the tropane ring were synthesized and evaluated for their monoamine transporter binding properties. The results show that binding to the dopamine and serotonin transporters (DAT and 5-HTT) is highly dependent on the specific linker used. Cyclo-3beta-(4-aminophenyl)-2beta-tropanemethanol pimelic acid ester/amide (5b) had an IC50 of 3.8 nM at the DAT. Cyclo-3beta-(4-aminophenyl)-2beta-tropanemethanol sebacic acid ester/amide (5e) had a Ki of 1.9 nM at the 5-HTT and was 68- and 737-fold selective for the 5-HTT relative to the DAT and NET. Small changes to the size as well as the electrostatic and hydrophobic properties of the 2,3-linker in 5b or 5e led to much less potent analogues at all three transporters. These results suggest that the high affinity for 5b and 5e at the DAT and 5-HTT may be due to their specific conformational properties.

Animals↗
PubMed2006

Use of multivariate analysis for optimization of separation parameters and prediction of migration time, resolution, and resolution per unit time in micellar electrokinetic chromatography.

The optimization of separation parameters in chromatography for better separation and resolution of analytes continues to be a labor intensive procedure usually performed by a trial and error method. A multivariate analysis in the form of multilinear regression (MLR) is used to optimize separation parameters and predict the migration behavior, resolution, and resolution per unit time of achiral (4-chlorophenol, pentachlorophenol, clonazepam, and diazepam) and chiral (1,1'-binaphthyl 2,2'-dihydrogen phosphate (BNP), and 1,1'-bi-2-naphthol (BOH)) compounds in MEKC. Separations of achiral and chiral analytes were performed using an achiral (poly(sodium N-undecylenic sulfate)) molecular micelle and chiral (poly(sodium N-undecanoyl-L-leucylvalinate) or poly(sodium N-undecanoyl-L-isoleucylvalinate)) molecular micelle, respectively, at various operating temperatures, applied voltages, pH values, and molecular micelle concentrations in the BGE. The separation parameters were subsequently used as input variables for MLR models. The models were validated with independent samples. The root-mean-square percent relative error (RMS%RE) is used as a figure of merit for characterizing the performance of the migration time, resolution, and resolution per unit time models. The RMS%RE obtained for predicted migrated times, resolutions, and resolution per unit time of 4-chlorophenol, pentachlorophenol, clonazepam, diazepam, BNP, and BOH ranged between 8 and 19%. The same experimental procedure was used to optimize the separation parameters of six other chiral analytes of different compound class. The predicted migration times, resolutions, and resolution per unit time of the chiral as well as the achiral analytes compare favorably with the experimental migration times and resolutions, indicating versatility and wide applicability of the technique in MEKC.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2006

Preparation of a monolithic column for weak cation exchange chromatography and its application in the separation of biopolymers.

A procedure for the preparation of a monolithic column for weak cation exchange chromatography was presented. The structure of the monolithic column was evaluated by mercury intrusion. The hydrodynamic and chromatographic properties of the monolithic column--such as back pressures at different flow rates, effects of pH on protein retention, dynamic loading capacity, recovery, and stability--were determined under conditions typical for ion-exchange chromatography. The prepared monolithic column might be used in a relatively broad pH range from 4.0 to 12.0 and exhibited an excellent separation to five proteins at the flow rates of both 1.0 and 8.0 mL/min, respectively. In addition, the prepared column was first used in the purification and simultaneous renaturation of recombinant human interferon gamma (rhIFN-gamma) in the extract solution with 7.0 mol/L guanidine hydrochloride. The purity and specific bioactivity of the purified rhIFN-gamma in only one chromatographic step were obtained to be 93% and 7.8 x 10(7) IU/mg, respectively.

Adsorption↗
PubMed2004

Strategy for analysis and screening of bioactive compounds in traditional Chinese medicines.

Traditional Chinese medicines (TCMs), due to their long time clinic test and reliable therapeutic efficacy, are attracting increased global attention served as excellent pools of bioactive compounds for the discovery of new drugs. However, hundreds or even thousands of components are usually contained in traditional Chinese medicines and only a few compounds are responsible for the pharmaceutical and/or toxic effects. The large numbers of other components in traditional Chinese medicines make the screening and analysis of the bioactive components extremely difficult. By the way, the combination effect of bioactive components on the pharmacological activity makes it very difficult to clear the therapeutic mechanism of TCMs. Therefore, some strategies have to design for screening of bioactive compounds in traditional Chinese medicines, which further leads to disclose the therapeutic mechanism of TCMs in molecular level. The review will summarize the present state of the art of screening strategy for active compounds in traditional Chinese medicines, and the chromatography methods for screening and analysis of bioactive compounds in traditional Chinese medicines will be emphasized.

Animals↗
PubMed2004

Total syntheses of (+)-chloropuupehenone and (+)-chloropuupehenol and their analogues and evaluation of their bioactivities.

Tetracyclic pyrans (+)-chloropuupehenone (1) and (+)-chloropuupehenol (5) and its C8-R-isomer (+)-3 were synthesized via a one-pot condensation of 1-chloro-2-lithio-3,5,6-tris(tert-butyldimethylsilyloxy)benzene (8) with (4aS,8aS)-3,4,4a,5,6,7,8,8a-octahydro-2,5,5,8a-tetramethylnaphthalene-1-carboxaldehyde (7). The major condensation product, (4aS,6aR,12bS)-2H-9,10-bis(tert-butyldimethylsilyloxy)-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene (4), after desilylation provided tetracyclic pyran (+)-(4aS,6aR,12bS)-2H-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene-9,10-diol (3). At a dosage of 42 mg/rat over 8 h, pyran diol 3 inhibited the intestinal absorption of cholesterol by 71% in rats. Tetracyclic pyran 4 was also converted to o-quinone 28, which inhibited cholesteryl ester transfer protein (CETP) activity and L1210 leukemic cell viability with IC(50) values of 31 and 2.4 microM, respectively. Diol (+)-5 inhibited CETP activity with an IC(50) value of 16 microM. The minor condensation product, (4aS,6aS,12bS)-2H-9,10-bis(tert-butyldimethylsilyloxy)-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene (6), was transformed into (+)-5 and (+)-1. A stepwise stereoselective synthesis of (+)-1 was also developed utilizing an oxyselenylation ring-closure reaction. The synthetic sequence also produced four biologically active naturally occurring drimanic sesquiterpenes, (+)-drimane-8alpha,11-diol (34), (-)-drimenol (38), (+)-albicanol (39), and (-)-albicanal (31) as intermediates.

Animals↗
PubMed2004

Monolithic column with zwitterionic stationary phase for capillary electrochromatography.

A capillary electrochromatography (CEC) monolithic column with zwitterionic stationary phases was prepared by in situ polymerization of butyl methacrylate, ethylene dimethacrylate, methacrylic acid, and 2-(dimethyl amino) ethyl methacrylate in the presence of porogens. The stationary phases have zwitterionic functional groups, that is, both tertiary amine and acrylic acid groups, so the ionization of those groups on the zwitterionic stationary phase was affected by the pH values of the mobile phase, and further affects the strength and direction of the electroosmotic flow (EOF). Separations of alkylbenzenes and polycyclic aromatic hydrocarbons based on the hydrophobic mechanism were obtained. Separation of various types of polar compounds, including phenols, anilines, and peptides, on the prepared column were performed under CEC mode with anodic and cathodic EOF, and different separation selectivities of those polar analytes were observed on the monolithic capillary column by using mobile phases with different pH values.

Journal Article↗
PubMed2004

Short columns with molecularly imprinted monolithic stationary phases for rapid separation of diastereomers and enantiomers.

Three molecularly imprinted monolithic columns with different length but almost identical column volume had been prepared. It was observed that the separation factors of diastereomers and enantiomers were almost unaffected by column length. However, the short column with dimension of 38 mm x 8 mm i.d. showed much lower resistance to flow rate so that it could be operated at much higher flow rates. By combining stepwise gradient elution with elevated flow rate, the diastereomers of cinchonine and cinchonidine and the enantiomers of Cbz-DL-Trp and Fmoc-DL-Trp were successfully separated within 3 min on the short column with dimension of 38 mm x 8 mm i.d. Based on the above results, a cinchonine imprinted monolithic disk with dimension of 10mm x 16 mm i.d. was further developed. The SEM image and the pore size distribution profile showed that large flow-through pores are present on the prepared monolith, which allowed mobile phase to flow through the disk with very low resistance. Chromatographic performances on the monolithic disk were almost unchanged compared with the long columns. A rapid separation of cinchonine and cinchonidine was achieved in 2.5 min at the flow rate of 9.0 ml/min. Furthermore, it was observed that there was almost no effect of the flow rate on the dynamic binding capacity at high flow rates. In addition, the effect of the loading concentration of analytes on the dynamic binding capacity, namely adsorption isotherm, was also investigated. A non-linear adsorption isotherm of cinchonine was observed on the molecularly imprinted monolith with cinchonine as template, which might be a main reason to result in the peak tailing of template molecule.

Chromatography, High Pressure Liquid↗
PubMed2004

Synthesis of chiral stationary phases with radical polymerization reaction of cellulose phenylcarbamate derivatives and vinylized silica gel.

Cellulose phenylcarbamate derivatives having methacrylate groups were synthesized with regioselective and non-regioselective procedures. These derivatives were chemically immobilized onto a vinylized silica gel, respectively, via a radical co-polymerization reaction. The immobilization was efficiently attained using a small amount of AIBN. The chiral recognition abilities of the prepared chiral stationary phases (CSPs) were evaluated by HPLC resolution of test enantiomers. It was observed that most of the enantiomers were completely resolved with markedly high column efficiency of 30,000-40,000 plates per metre for the eluted peaks. The effect of the amount of methacrylolyl chloride used for preparation on resolution was investigated. A direct comparison of the chiral recognition ability was made on the regioselectively and non-regioselectively prepared CSPs. In addition, the chemically bonded-type of CSPs were found to be relatively stable with addition of solvents such as tetrahydrofuran (THF) and chloroform into the mobile phase, which can lead to the dissolution of cellulose derivatives on the coated CSPs. Thus the choice of solvents used as the mobile phase is greatly extended and better resolution of several test enantiomers was observed on the prepared CSPs with THF and chloroform as a composition in the mobile phase. The batch-to-batch and run-to-run reproducibility was also discussed on the newly prepared CSPs.

Carbamates↗
PubMed2004

[Nasal deviation rectification: a report of 11 cases].

OBJECTIVE: To observe septo-rhinoplasty therapeutic effect on nasal deviation and to introduce the methods of the operation. METHOD: Eleven cases of nasal deviation with deviation of nasal septum should receive a septo-rhinoplasty. RESULT: Eleven cases of nasal deviation patients obtained satisfied curative effect. Nasal deviation and deviation of nasal septum need only one rectification, choosing seven cases neither have complication. CONCLUSION: Nasal deviation patients could be completely rectified by only one septo-rhinoplasty operation, what's more, it isn't limited by the age.

Adolescent↗
PubMed2004

[Cross-linked beta-cyclodextrin polymer used for bilirubin removal].

A new material for adsorption of bilirubin was synthesized with cross-linking reaction of beta-cyclodextrin. The kinetic adsorption behaviors of bilirubin such as the effects of temperature, pH, the initial bilirubin concentration as well as bovine seum albumin on the removal of bilirubin have been investigated. It is demonstrated that bilirubin could be adsorbed well on the prepared sorbent quickly and higher temperature favored the adsorpion of bilirubin. The percentage of removal of bilirubin reached 92.6% with initial bilirubin concentration of 40 mg/L in phosphate buffer at pH 7.8. With the increase of initial bilirubin concentration, the percentage of removal of bilirubin decreased; however, the adsorption capacity increased.

Adsorption↗
PubMed2003

Identification of a nuclear orphan receptor (Ear2) as a negative regulator of renin gene transcription.

A potent transcriptional enhancer was previously identified upstream of the mouse renin gene. Within the enhancer is a TGACCT direct-repeat motif, required for enhancer activity, that is the consensus sequence recognized by members of the thyroid hormone subfamily of steroid hormone receptors. We previously reported that RAR/RXR bind to this sequence and mediate the induction of renin promoter activity by retinoids. However, gel mobility shift assays clearly show that other as yet unidentified factors also bind to this motif. In order to identify some of these TGACCT binding factors, we screened a yeast one-hybrid cDNA library derived from mouse As4.1 cells. One of these encoded the orphan nuclear receptor Ear2. Recombinant Ear2 was purified from Escherichia coli and an antipeptide antisera was generated. EMSA showed that purified recombinant Ear2 specifically binds the TGACCT direct-repeat motif. Transfection assays showed that Ear2 potently decreases both baseline and retinoid-induced mouse renin promoter activity in a dose-dependent, enhancer-dependent, and sequence-specific manner. Mutations in Ear2, which abolish its binding to the TGACCT motif, also abolish transcriptional repression. Ear2 was identified as a nuclear protein in As4.1 cells, is one of the proteins binding to the TGACCT repeat motif, and its overexpression can repress transcription of the endogenous renin gene in As4.1 cells. These data suggest that Ear2 is a negative modulator of renin gene transcription in As4.1 cells, and that the renin enhancer may actually encode a complex positive and negative regulator of transcription.

Animals↗
PubMed2003

Molecularly imprinted monolithic stationary phases for liquid chromatographic separation of enantiomers and diastereomers.

The method for preparation of molecularly imprinted monolithic stationary phase has been improved to achieve liquid chromatographic separation of enantiomers and diastereomers. By adopting low polar porogenic solvents of toluene and dodecanol and optimal polymerization conditions, the molecularly imprinted monolithic stationary phases with good flow-through properties and high resolution were prepared. Enantiomers of amino acid derivatives and diastereomers of cinchona alkaloids were completely resolved using the monolithic stationary phases. The influence of porogenic composition, monomer-template ratio and polymerization conditions on the chromatographic performance was investigated. Some chromatographic conditions such as the composition of the mobile phase and the temperature were characterized. Scanning electron microscopy showed that the molecularly imprinted monolithic stationary phase has a large through-pore structure to allow the mobile phase to flow through the column at very low backpressure. Accelerated separations of enantiomers and diastereomers were therefore achieved at elevated flow rates. Finally, the chiral recognition performance of the prepared stationary phase in aqueous media was investigated. Hydrophobic interaction, and ionic and/or hydrogen bonding interactions were proposed to be responsible for the recognition mechanism.

Chromatography, High Pressure Liquid↗
PubMed2003

The separation of biomolecules using capillary electrochromatography.

The unique properties of capillary electrochromatography such as high performance, high selectivity, minimum consumption of both reagents and samples, and good compatibility with mass spectrometry make this technique an attractive one for the analysis of biomolecules including peptides, proteins, carbohydrates, nucleosides and nucleotides. Irreversible adsorption between the biomolecules and the charged packing surface leads to a lack of reproducibility and serious peak tailing, so various approaches have been taken to overcome this and to improve the technique for future challenges.

Biopolymers↗
PubMed2003

Nitric oxide modulates MCP-1 expression in endothelial cells: implications for the pathogenesis of pulmonary granulomatous vasculitis.

Monocyte chemoattractant protein-1 (MCP-1) is a pivotal mediator of angiocentric granuloma formation in glucan-induced pulmonary granulomatous vasculitis. Based on the rationale that mononuclear phagocytes retrieved from granulomas are rich sources of nitric oxide (NO) and that the recruitment of mononuclear phagocytes into lesions abates as granuloma formation slows, we tested the hypothesis that MCP-1 gene expression is regulated by a NO-sensitive mechanism. Preexposure of endothelial cell (EC) monolayers to NO donor compounds markedly reduced cytokine-induced MCP-1 expression and cytosolic-to-nuclear translocation of nuclear factor-kappa B (NF-kappaB), reversed fluctuations in endothelial reduced glutathione (GSH) pools but did not affect cGMP concentrations. The lungs of mice bearing targeted disruptions of the inducible nitric oxide synthase (iNOS) gene exhibited significantly higher concentrations of MCP-1 following glucan infusion than did those of wild-type mice. Cumulatively, these data suggest that NO suppresses MCP-1 expression by blunting the redox changes associated with cytokine-induced EC activation.

Animals↗
PubMed2002

Analysis of prognostic factors for T(1)N(0)M(0) glottic cancer treated with definitive radiotherapy alone: experience of the cancer hospital of Peking Union Medical College and the Chinese Academy Of Medical Sciences.

PURPOSE: To analyze the prognostic factors for early-stage glottic cancer (T(1)N(0)M(0)) treated with radiotherapy alone. METHODS AND MATERIALS: Between 1958 and 1994, 238 patients (220 male) with T(1)N(0)M(0) (UICC 1997) squamous cell carcinoma of the glottis were treated with 6- or 8 MV X-ray or 60Co radiation in parallel-opposed fields (median size: 22.5 cm(2)) over a median of 52 days to a median dose of 68 Gy. Locoregional control (LC) and overall survival (OS) were estimated by the Kaplan-Meier method. Log-rank and Cox regression analyses were used to identify prognostic factors. RESULTS: The median follow-up time was 127 months (range: 4-410 months). Five- and 10-year OS rates were 84.0% and 74.9%. The 5-year LC rate was 82.2%. Forty-four patients had recurrent disease (41 locally, 2 in cervical lymph nodes, 1 lost to follow-up); 23 had second malignancies. On multivariate analysis, unfavorable prognostic factors for OS were age >65 years (p < 0.001) and second malignancy (p < 0.001). Unfavorable prognostic factors for LC were bulky tumor (p = 0.023), anterior commissure involvement (p = 0.024), and decrease in hemoglobin during treatment (p = 0.025). CONCLUSIONS: Radiotherapy alone provides good control of early-stage glottic cancer. Bulky tumor, anterior commissure involvement, and decreasing hemoglobin are negative prognostic factors for LC.

Adult↗
PubMed2002

High-performance affinity chromatography for characterization of human immunoglobulin G digestion with papain.

Reactive continuous rods of macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) were prepared within the confines of a stainless steel column. Then papain was immobilized on these monoliths either directly or linked by a spacer arm. In a further step, a protein A affinity column was used for the characterization of the digestion products of human immunoglobulin G (IgG) by papain. The results showed that papain immobilized on the monolithic rod through a spacer arm exhibits higher activity for the digestion of human IgG than that without a spacer arm. The apparent Michaelis-Menten kinetic constants of free and immobilized papain, K(m) and V(max), were determined. The digestion conditions of human IgG with free and immobilized papain were optimized. Comparison of the thermal stability of free and immobilized papain showed that the immobilized papain exhibited higher thermal stability than the free enzyme. The half-time of immobilized papain reaches about a week under optimum pH and temperature conditions.

Chromatography, Affinity↗
PubMed2002

Syntheses and bioactivities of substituted 9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4,5,8-tetrones. Unusual reactivities with amines.

A number of substituted 9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4,5,8-tetrones have been synthesized and their anticancer and antimalarial activities evaluated. A one-pot synthesis of 2,5,8-trimethoxy-9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4-dione (4) was achieved by heating a mixture of 1,4-dimethoxyanthracene, methoxyhydroquinone, silver oxide, and zinc iodide in toluene. Regioselective bromination of 4 and 2-methoxy-9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4,5,8-tetrone (7) with N-bromosuccinimide provided 2-bromo-3,5,8-trimethoxy-9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4-dione and 2-bromo-3-methoxy-9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4,5,8-tetrone (1), respectively. The reactions of 1 with aliphatic primary amines and secondary amines, respectively, produced different products, a result most likely attributed to the different basicities (or nucleophilicities) and steric effects of the two kinds of amines. The structure of the displacement product, 2-bromo-3-[2-(tert-butoxycarbonyl)ethylamino]-9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4,5,8-tetrone, from the reaction of 1 with tert-butyl 3-aminopropanoate was unequivocally determined by a single-crystal X-ray analysis. IC(50) values of triptycene bisquinones for the inhibition of L1210 leukemia cell viability are in the 0.11-0.27 microM range and for the inhibition of Plasmodium falciparum 3D7 are in the 4.7-8.0 microM range.

Amines↗