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Biomedical subjects

Hui Liu

Publications and source records attributed to Hui Liu.

At least 109 records · Page 6Linked to original sources
PubMed2005

Synthesis of dendritic catalysts and application in asymmetric transfer hydrogenation.

Frechet-type core-functionalized chiral diamine-based dendritic ligands and hybrid dendritic ligands condensed from polyether wedge and Newkome-type poly(ether-amide) supported multiple ligands were designed and synthesized. The solubility of hybrid dendrimers was found to be finely controlled by the polyether dendron. The catalytic efficiency and recovery use of dendritic ruthenium complexes were compared in the transfer hydrogenation of acetophenone. The core-functionalized dendritic catalysts demonstrated much better recyclability, which verified the stabilizing effects of the bulky polyether wedge on the catalytically active complex. Moreover, the dendritic catalysts were applied in the asymmetric transfer hydrogenation of ketones, enones, imine, and activated olefin, and moderate to excellent enantioselectivitiy was achieved comparable to that of monomeric catalysts.

Journal Article↗
PubMed2005

Efficient synthesis of the glucosidase inhibitor blintol, the selenium analogue of the naturally occurring glycosidase inhibitor salacinol.

An efficient synthesis of blintol, the selenium congener of the naturally occurring glycosidase inhibitor salacinol, and a potent glucosidase inhibitor itself, is described. Unlike our previously reported synthesis, this improved route makes use of p-methoxybenzyl ether protecting groups in the synthesis of one of the two key intermediates, 2,3,5-tri-O-p-methoxybenzyl-1,4-anhydro-4-seleno-D-arabinitol, from L-xylose. The other key intermediate, 2,4-O-benzylidene-L-erythritol-1,3-cyclic sulfate, was successfully prepared from D-glucose instead of the expensive L-glucose. All protecting groups in the resulting adducts were removed with trifluoroacetic acid to yield a mixture of stereoisomers, thereby obviating the problematic deprotection of benzyl ethers by hydrogenolysis. The major stereoisomer, blintol, was then obtained by fractional crystallization.

Celastraceae↗
PubMed2005

The effect of hydrodynamics-based delivery of an IL-13-Ig fusion gene for experimental autoimmune myocarditis in rats and its possible mechanism.

Interleukin (IL)-13 is a pleiotropic cytokine secreted by activated Th2 T lymphocytes. Th1 cytokines are assumed to exacerbate and Th2 cytokines to ameliorate rat experimental autoimmune myocarditis (EAM). Here, we examined the effect of IL-13 on EAM, using a hydrodynamics-based delivery of an IL-13-Ig fusion gene, as well as the possible mechanism of its effect. Rats were immunized on day 0, and IL-13-Ig-treated rats were injected with pCAGGS-IL-13-Ig, and control rats with pCAGGS-Ig, on day 1 or 7. On day 17, the IL-13-Ig gene therapy was effective in controlling EAM as monitored by a decreased heart weight/body weight ratio, by reduced myocarditis and by reduced atrial natriuretic peptide mRNA in the heart, as a heart failure marker. On the basis of IL-13 receptor mRNA expression in separated cells from EAM hearts, we proposed that IL-13-Ig target cells were CD11b(+) cells and non-cardiomyocytic noninflammatory (NCNI) cells, such as fibroblasts, smooth muscle or endothelial cells. IL-13-Ig inhibited expression of the genes for prostaglandin E synthase, cyclooxygenase-2, inducible nitric oxide synthase, IL-1beta and TNF-alpha in cultivated cells from EAM hearts, while it enhanced expression of the IL-1 receptor antagonist gene. We conclude that IL-13-Ig ameliorates EAM and suppose that its effectiveness may be due to the influence on these immunologic molecules in CD11b(+) and NCNI cells.

Animals↗
PubMed2005

Using fourier spectrum analysis and pseudo amino acid composition for prediction of membrane protein types.

Membrane proteins are generally classified into the following five types: (1) type I membrane protein, (2) type II membrane protein, (3) multipass transmembrane proteins, (4) lipid chain-anchored membrane proteins, and (5) GPI-anchored membrane proteins. Given the sequence of an uncharacterized membrane protein, how can we identify which one of the above five types it belongs to? This is important because the biological function of a membrane protein is closely correlated with its type. Particularly, with the explosion of protein sequences entering into databanks, it is in high demand to develop an automated method to address this problem. To realize this, the key is to catch the statistical characteristics for each of the five types. However, it is not easy because they are buried in a pile of long and complicated sequences. In this paper, based on the concept of the pseudo amino acid composition (Chou, K. C. (2001). PROTEINS: Structure, Function, and Genetics 43: 246-255), the technique of Fourier spectrum analysis is introduced. By doing so, the sample of a protein is represented by a set of discrete components that can incorporate a considerable amount of the sequence order effects as well as its amino acid composition information. On the basis of such a statistical frame, the support vector machine (SVM) is introduced to perform predictions. High success rates were yielded by the self-consistency test, jackknife test, and independent dataset test, suggesting that the current approach holds a promising potential to become a high throughput tool for membrane protein type prediction as well as other related areas.

Amino Acids↗
PubMed2005

Organochlorine pesticides (DDTs and HCHs) in soils from the outskirts of Beijing, China.

Concentrations of HCH (hexachlorocyclohexane) and DDT (Dichlorodiphenyltrichloroethane) were determined in shallow subsurface (5-30 cm depth) and deep soil layers (150-180 cm depth) from the outskirts of Beijing, China. Concentrations of total HCHs (including alpha, beta, gamma, delta-isomers) and total DDTs (including p,p'-DDT, p,p'-DDE, p,p'-DDD, o,p'-DDT) in shallow subsurface soils ranged from 1.36 to 56.61 ng/g dw (median 5.25 ng/g), and from 0.77 to 2178 ng/g (median 38.66 ng/g), respectively, and those in the deeper layers were approximately an order of magnitude less. The spatial distribution of HCHs and DDTs reflected the known historical usage of these pesticides. No correlation between the concentrations of pesticides and soil organic matter content or clay content can be found. The factors affecting residue levels and compositions of DDT and HCH were discussed. The contour maps of beta/gamma ratios and DDT/DDE ratios for both the shallow subsurface and deep layer soils were drawn.

Aluminum Silicates↗
PubMed2005

Effects of megestrol acetate on pituitary function and end-organ hormone secretion: a post hoc analysis of serum samples from a 12-week study in healthy older men.

BACKGROUND: Megestrol acetate (MA) is a synthetic progestin commonly used to promote weight gain in malnourished older individuals. In small studies, MA administration has been associated with reduced serum cortisol concentrations in patients with cancer or AIDS. The impact of MA on the pituitary secretion of adrenocorticotropic hormone (ACTH) and other hormones is unclear, and the prevalence and extent of hypocortisolemia in older individuals after MA treatment is unknown. A randomized, placebo-controlled study of the effects of testosterone (T) and resistance training (RT) on body composition after MA administration in older men has been reported previously. OBJECTIVE: The purpose of this post hoc analysis was to examine the effect of 12 weeks of MA on pituitary function and end-organ hormone secretion in healthy older individuals using frozen serum samples from that study. METHODS: The previous study was conducted at the Department of Geriatrics, Donald W. Reynolds Center on Aging and the General Clinical Research Center at The University of Arkansas for Medical Sciences, Little Rock, Arkansas. Healthy male volunteers aged 60 to 85 years were recruited from the center and were randomly assigned to 1 of 4 study groups: RT + T, T, RT + placebo (P), or P. Subjects enrolled in the RT groups underwent supervised upper- and lower-body strength-training exercises 3 d/wk at 80% of 1 repetition maximum. Subjects in the groups to receive T received injections of testosterone enanthate 100 mg i.m. QW for 12 weeks. Subjects receiving P were given 1-mL saline injections i.m. QW for 12 weeks. All subjects received MA 800 mg p.o. QD concurrently for 12 weeks. For the present analysis, serum concentrations of the pituitary hormones follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), ACTH, prolactin (PRL), and luteinizing hormone (LH), as well as the end-organ hormones estradiol (E2), cortisol, free T4, and T, were measured in samples obtained at baseline (week 0) and after 12 weeks of MA treatment. RESULTS: Serum samples from 21 men (mean [SD]age, 67.0 [7.3]years; mean [SD] body mass index, 23.1 [10.4] kg/m2; mean [SD] percentage of body fat, 22.5% [8.8%]; RT + T, T, RT + P, and P groups, n = 4, 5, 6, and 6 subjects, respectively) were available from the original study. The mean percentage changes from baseline in serum pituitary hormone concentrations after 12 weeks of MA administration were as follows: TSH, -14.7%; ACTH, -89.5%; PRL, 162.2%; and LH, -49.0%; (P = 0.03, <0.001, <0.001, and <0.001, respectively). The mean (SD) percentage changes from baseline in serum end-organ hormone concentrations with MA at 12 weeks were as follows: E2, 181.6%; and cortisol, -90.8% (both, P < 0.001). In the P and RT + P groups, the mean percentage changes from baseline in T were -84% and -85%, respectively (both, P < 0.001). FSH and free T4 concentrations were not significantly changed. CONCLUSIONS: This analysis of serum samples from healthy older men suggests that MA administration significantly affected the secretion of several pituitary hormones and end-organ hormone synthesis. Most notably, ACTH secretion and serum cortisol levels were statistically significantly suppressed in 20 of 21 subjects, without the development of clinically significant adrenal suppression.

Aged↗
PubMed2005

Risk factors for sexually transmitted disease among rural-to-urban migrants in China: implications for HIV/sexually transmitted disease prevention.

The objective of the study was to identify risk factors associated with sexually transmitted diseases (STDs) among rural-to-urban migrants in Beijing in 2002. Migrants with STDs consisted of 432 migrants who sought STD care in two public STD clinics. Migrants without STDs included 892 migrants recruited from 10 occupational clusters. Multiple logistic regression was used for data analysis. Compared to migrants without STDs, migrants with STDs were more likely to report having engaged in commercial sex (selling or buying sex) (odds ratio [OR] = 2.70, 95% confidence interval [CI]: 1.71-4.25), multiple sex partners in the previous month (OR = 6.50, 95% CI: 3.73-11.32) and higher perceived HIV-related stigma (OR = 1.89, 95% CI: 1.30-2.75). Being a migrant with an STD was also associated with female gender (OR = 4.10, 95% CI: 2.89-5.82), higher education (OR = 2.92, 95% CI: 1.40-6.06), and higher monthly salary (OR = 1.68. 95% CI: 1.23-2.29). Migrants with STDs visited their hometowns more frequently and had more stable jobs than migrants without STDs. Approximately 10% of the migrants with STDs and 7.7% of the migrants without STDs always used condoms. This study suggests that among migrants, acquisition of an STD is associated with higher participation in risk behaviors as would be expected, but also with higher perceived stigma, education, stable jobs, salary, and with female gender. Appropriate behavioral intervention programs are advocated to reduce the risk and stigma among the special population.

Adult↗
PubMed2005

HPLC determination and pharmacokinetics of osthole in rat plasma after oral administration of Fructus Cnidii extract.

A simple and sensitive high-performance liquid chromatographic (HPLC) method is developed for the determination of osthole in rat plasma and applied to a pharmacokinetic study in rats after administration of Fructus Cnidii extract. After addition of fluocinonide as an internal standard, plasma samples are extracted with diethyl ether. HPLC analysis of the extracts is performed on a Hypersil ODS2 analytical column, using methanol-0.4% acetic acid (65:35, v/v) as the mobile phase. The UV detector is set at 322 nm. The standard curve is linear over the range 0.0520-5.20 microg/mL (r = 0.9979). The mean extraction recoveries of osthole at three concentrations were 81.0%, 91.2%, and 90.7%, respectively. The intra- and interday precisions have relative standard deviations from 1.9% to 4.9%. The limit of quantitation is 0.0520 microg/mL. The HPLC method developed can easily be applied to the determination and pharmacokinetic study of osthole in rat plasma after the animals are given the Fructus Cnidii extract. The plasma concentration of osthole from six rats showed a Cmax of 0.776 +/- 0.069 microg/mL at Tmax of 1.0 +/- 0.3 h.

Administration, Oral↗
PubMed2005

Heterosexual transmission of HIV in China: a systematic review of behavioral studies in the past two decades.

OBJECTIVE: The objective of this study was to address the role of heterosexual transmission of HIV in China. GOAL: The goal of this study was to explore the prevalence of unsafe sex and the likelihood of HIV spread heterosexually from core populations to others. STUDY: The authors conducted a review of behavioral studies. RESULTS: Drug users were more likely to be involved in higher-risk sexual behaviors than were those who abstained from using drugs. Most female drug users (52-98%) reported having engaged in commercial sex. Most female sex workers (FSWs) and individuals with sexually transmitted diseases (STDs) had concurrent sexual partners. Many continued to have unprotected sex after noticing STD symptoms in themselves or their sexual partners. From 5% to 26% of rural-to-urban migrants had multiple sexual partners and 10% of males patronized FSWs during migration. CONCLUSIONS: Factors such as high rates of FSW patronage, low rates of condom use during commercial sex, having sex with both commercial and noncommercial sexual partners, and high rates of STD infection may promote a heterosexual epidemic in China.

Behavioral Research↗
PubMed2005

Effects of sodium phenylbutyrate on differentiation and induction of the P21WAF1/CIP1 anti-oncogene in human liver carcinoma cell lines.

OBJECTIVES: To explore the effects of sodium phenylbutyrate on the proliferation, differentiation, cell cycle arrest and induction of the P(21WAF1/CIP1) anti-oncogene in human liver carcinoma cell lines Bel-7402 and HepG2. METHODS: Bel-7402 and HepG2 human liver carcinoma cells were treated with sodium phenylbutyrate at different concentrations. Light microscopy was used to observe morphological changes in the carcinoma cells. Effects on the cell cycle were detected by using flow cytometry. P(21WAF1/CIP1) expression was determined by both reverse transcription-polymerase chain reaction and western blotting. Statistical analysis was performed by using one-way anova and Student's t-test. RESULTS: Sodium phenylbutyrate treatment caused time- and dose-dependent growth inhibition of Bel-7402 and HepG2 cells. This treatment also caused a decline in the proportion of S-phase cells and an increase in the proportion of G(0)/G(1) cells. Sodium phenylbutyrate increased the expression of P(21WAF1/CIP1). CONCLUSIONS: Sodium phenylbutyrate inhibits the proliferation of human liver carcinoma cells Bel-7402 and HepG2, induces partial differentiation, and increases the expression of P(21WAF1/CIP1).

Carcinoma, Hepatocellular↗
PubMed2005

Generation and characterization of C305, a murine neutralizing scFv antibody that can inhibit BLyS binding to its receptor BCMA.

B-lymphocyte stimulator (BLyS) is a member of the tumor necrosis factor (TNF) family and a key regulator of B cell response. Neutralizing single-chain fragment variable (scFv) antibody against BLyS binding to its receptor BCMA has the potential to play a prominent role in autoimmune disease therapy. A phage display scFv library constructed on pIII protein of M13 filamentous phage was screened using BLyS. After five rounds of panning, their binding activity was characterized by phage-ELISA. Nucleotide sequencing revealed that at least two different scFv gene fragments (C305 and D416) were obtained. The two different scFv gene fragments were expressed to obtain the soluble scFv antibodies, then the soluble scFv antibodies were characterized by means of competitive ELISA and in vitro neutralization assay. The results indicated that C305 is the neutralizing scFv antibody that can inhibit BLyS binding to its receptor BCMA.

Amino Acid Sequence↗
PubMed2005

Acoustic positioning using multiple microphone arrays.

Passive acoustic techniques are presented to solve the localization problem of a sound source in three-dimensional space using off-the-shelf hardware. Multiple microphone arrays are employed, which operate independently, in estimating the direction of arrival of sound, or, equivalently, a direction vector from the array's geometric center towards the source. Direction vectors and array centers are communicated to a central processor, where the source is localized by finding the intersection of the direction lines defined by the direction vectors and the associated array centers. The performance of the method in the air is demonstrated experimentally and compared with a state-of-the-art method that requires centralized digitization of the signals from the microphones of all the arrays.

Acoustics↗
PubMed2005

Efficient therapeutic gene expression in cultured rat hippocampal neurons mediated by human foamy virus vectors: a potential for the treatment of neurological diseases.

Vectors derived from human foamy virus (HFV), with their nonpathogenic nature and a wide tissue tropism, have been successfully used as retroviral gene transfer vehicles. However, transduction of primary hippocampal neurons (HNs) with HFV vectors has little been studied. To investigate the potential of HFV-derived vector in gene therapy for neurological diseases, efficient foreign gene expression in cultured rat HNs was first demonstrated by successful enhanced green fluorescent protein (EGFP) transduction through a HFV vector bearing an EGFP expression cassette. Furthermore, we tested the effect on HNs that were transduced by a novel HFV vector expressing the human glutamic acid decarboxylase (GAD) cDNA, a therapeutic gene for neurological disorders such as epilepsy and Parkinson's disease. The transduced HNs showed significant increase in isoform-specific expression of GAD, synthesis of gamma-aminobutyric acid (GABA) and stimulation-evoked GABA release. These findings indicated for the first time that cultured rat HNs could be efficiently transduced by HFV vectors, and the GAD-expressing HFV vector has potential therapeutic value in the treatment of neurological diseases.

Animals↗
PubMed2005

Design and evaluation of compound metformin/glipizide elementary osmotic pump tablets.

A simple elementary osmotic pump (EOP) system that could deliver metformin hydrochloride (MT) and glipizide (GZ) simultaneously for extended periods of time was developed in order to reduce the problems associated with multidrug therapy of type 2 non-insulin-dependent diabetes mellitus. In general, both highly and poorly water-soluble drugs are not good candidates for elementary osmotic delivery. However, MT is a highly soluble drug with a high dose (500 mg) while GZ is a water-insoluble drug with a low dose (5 mg) so it is a great challenge to pharmacists to provide satisfactory extended release of MT and GZ. In this paper sodium carbonate was used to modulate the solubility of GZ within the core and MT was not only one of the active ingredients but also the osmotic agent. The optimal EOP was found to deliver both drugs at a rate of approximately zero order for up to 10 h in pH 6.8, independent of environment media. In-vivo evaluation was performed relative to the equivalent dose of conventional MT tablet and GZ tablet by a cross-study in six Beagle dogs. The EOP had a good sustained effect in comparison with the conventional product. The prototype design of the system could be applied to other combinations of drugs used for cardiovascular diseases, diabetes, etc.

Delayed-Action Preparations↗
PubMed2005

[Effects of ethyl pyruvate on cell-mediated immune function in rats with delayed resuscitation after burn injury].

OBJECTIVE: To investigate the effects of ethyl pyruvate (EP) on cell-mediated immune function in rats with delayed resuscitation after burn injury, and its potential regulatory mechanism. METHODS: Wistar rats were subjected to 30% full-thickness scald injury with delayed resuscitation. One hundred and three male rats were randomly divided into normal controls (n=7), sham scald group (n=32), scald group (n=32) in which 40 ml/kg normal saline was infused peritoneally 6 hours after scald, and EP treatment group (n=32) in which 40 mg/kg EP was injected peritoneally 6 hours after scald. Animals were sacrificed on postburn day 1, 3, 5, and 7, and spleen was collected to determine splenocyte proliferation, IL-2 production and cell-surface IL-2 receptor (IL-2R) expression. RESULTS: Splenic lymphocyte proliferation responses to T cell mitogen, concanavalin A (Con A), were depressed from 1 to 7 days after scald injury (all P<0.05). Meanwhile, in comparison with sham scald group, burn injury resulted in a significant decrease in splenic production of IL-2 on postburn day 1, 3, as well as 5, and a marked suppression of IL-2R expression on days 1 and 3 postburn (all P<0.05). Treatment with EP after burn injury showed a dramatic restoration of lymphocyte proliferation rate and increased production of IL-2 at various time points (all P<0.05). However, treatment with EP did not affect IL-2R expression compared with scalded rats (all P>0.05). CONCLUSION: Treatment with EP could markedly elevate splenic T lymphocyte proliferation response and increase production of IL-2 following burn injury, thereby improving cell-mediated immunity in thermally injured rats with delayed resuscitation.

Animals↗
PubMed2005

[External radiation and combined transcatheter arterial chemoembolization for unresectable primary liver cancer].

BACKGROUND & OBJECTIVE: Transcatheter arterial chemoembolization (TACE) is the routine treatment for unresectable primary liver cancer, but 3-year survival rate of patients received TACE alone is only about 20%. This research was to evaluate efficacy of external radiotherapy (RT) combined with TACE on unresectable primary live cancer. METHODS: From Jun. 1994 to Apr. 2002, 114 patients with unresectable primary liver cancer were non-randomized to receive TACE plus RT (54 patients), or TACE alone (60 patients) as control. For TACE, after skiagram confirmed catheterization, suspension of 300 mg of carboplatin, 50-60 mg of epirubicin, 14-20 mg of mitomycin, and 10-30 ml of iodized oil was perfused into hepatic arteries, 1-2 mm of Gelfoam particles was given to embolize hepatic arteries according to blood supply conditions of tumors, this process was repeated every 4-8 weeks. Either group was treated with 1-4 sessions of TACE. In TACE+RT group, patients received radiation on tumor and generous margin 21-28 days after TACE. The radiation dose was 46-60 Gy in daily 2 Gy fractions. RESULTS: In TACE+RT group, response rate (AFP titer decrease of >50%) was 61.1%, and 1-, 2-, 3-year survival rates of TACE+RT group were significantly higher than those of TACE group (66.5% vs. 53.9%, 48.4% vs. 37.2%, and 37.4% vs. 17.8%, P<0.05). Three-year survival rate correlated with tumor size, liver function grade, and portal vein embolus. CONCLUSION: TACE combined with RT may prolong survival time of patients with unresectable primary live cancer.

Adult↗