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Biomedical subjects

Hongwei Xu

Publications and source records attributed to Hongwei Xu.

15 recordsLinked to original sources
PubMed2006

A validated gene expression model of high-risk multiple myeloma is defined by deregulated expression of genes mapping to chromosome 1.

To molecularly define high-risk disease, we performed microarray analysis on tumor cells from 532 newly diagnosed patients with multiple myeloma (MM) treated on 2 separate protocols. Using log-rank tests of expression quartiles, 70 genes, 30% mapping to chromosome 1 (P < .001), were linked to early disease-related death. Importantly, most up-regulated genes mapped to chromosome 1q, and down-regulated genes mapped to chromosome 1p. The ratio of mean expression levels of up-regulated to down-regulated genes defined a high-risk score present in 13% of patients with shorter durations of complete remission, event-free survival, and overall survival (training set: hazard ratio [HR], 5.16; P < .001; test cohort: HR, 4.75; P < .001). The high-risk score also was an independent predictor of outcome endpoints in multivariate analysis (P < .001) that included the International Staging System and high-risk translocations. In a comparison of paired baseline and relapse samples, the high-risk score frequency rose to 76% at relapse and predicted short postrelapse survival (P < .05). Multivariate discriminant analysis revealed that a 17-gene subset could predict outcome as well as the 70-gene model. Our data suggest that altered transcriptional regulation of genes mapping to chromosome 1 may contribute to disease progression, and that expression profiling can be used to identify high-risk disease and guide therapeutic interventions.

Aged↗
PubMed2006

Study on the fluorescence behavior of p-sulfonated calix[4,6]arene in cationic surfactant cetyltrimethylammonium bromide solution and its analytical application.

The fluorescence properties of p-sulfonated calix[4,6]arene (SCnA, n=4, 6) in cationic surfactant cetyltrimethylammonium bromide (CTAB) solution were investigated. It was found that the fluorescence intensity of SCnA could be enhanced markedly by an appropriate amount of CTAB. The results indicate the formation of complex between CTAB and SCnA at a 1:1 complex stoichiometry and their association constants were calculated by applying a deduced equation. Based on the obtained results, a new fluorimetric method has been developed for rapid determination of SCnA with a good linearity in the concentration range of 2x10(-7) to 7x10(-6)mol L-1.

Buffers↗
PubMed2006

Hairy roots induced by Agrobacterium rhizogenes and production of regenerative plants in hairy root cultures in maize.

Hairy roots of maize were induced by infecting 15-d calli with Agrobacterium rhizogenes. The hairy roots cultured in hormone-free media showed the vigorous growth and typical hairy root features. The regenerated plants were produced from hairy roots in MS media supplemented with 1.6 mg/L ZT and 0.4 mg/L NAA. The PCR-Southern hybridization demonstrated that T-DNA had been integrated into the chromosome of regenerated plants.

Blotting, Southern↗
PubMed2006

Effects of Ginkgo biloba extract on cell proliferation, cytokines and extracellular matrix of hepatic stellate cells.

BACKGROUND/AIMS: Hepatic fibrosis is the common wound-healing response to chronic liver injury. Ginkgo biloba extract (GbE) has been indicated to reverse hepatic fibrosis and exhibit therapeutic effects both in vitro and in vivo. This study aimed to investigate the underlying mechanism of GbE using HSC-T6 cells, a subline of hepatic stellate cells (HSC) as a model. METHODS: HSC-T6 cells were seeded into six-well plates and allowed to attach overnight. After exposure to different concentrations of GbE761 for 24 or 48 h, cell cycle analysis, semiquantitative RT-PCR, Western blotting analysis and analysis of ECM secretion were performed. RESULTS: It was revealed that GbE (1, 10, 100, 500 mg/l) suppressed HSC proliferation and caused G0/G1 phase arrest in a concentration-dependent manner. RT-PCR and Western blot assays were applied to detect the decline of transforming growth factor beta1(TGF-beta1) and connective tissue growth factor (CTGF) in both mRNA and protein levels after GbE treatment in HSC-T6 cells for 24 or 48 h. Meanwhile, GbE inhibited the synthesis of type I and type III collagens. Secretion of some extracellular matrix (ECM) proteins, such as type III procollagen (PC III), type IV collagen (collagen IV), laminin (LN), hyaluronic acid (HA), were all decreased in supernatant of GbE treated HSC cells. CONCLUSIONS: Our results suggest that GbE confers its anti-fibrosis effects through inhibiting HSC proliferation, reducing TGF-beta1 and CTGF expression and consequently suppressing the collagen production and ECM secretion.

Animals↗
PubMed2005

ABAD enhances Abeta-induced cell stress via mitochondrial dysfunction.

Amyloid-beta peptide (Abeta) binding alcohol dehydrogenase (ABAD), an enzyme present in neuronal mitochondria, is a cofactor facilitating Abeta-induced cell stress. We hypothesized that ABAD provides a direct link between Abeta and cytotoxicity via mitochondrial oxidant stress. Neurons cultured from transgenic (Tg) mice with targeted overexpression of a mutant form of amyloid precursor protein and ABAD (Tg mAPP/ABAD) displayed spontaneous generation of hydrogen peroxide and superoxide anion, and decreased ATP, as well as subsequent release of cytochrome c from mitochondria and induction of caspase-3-like activity followed by DNA fragmentation and loss of cell viability. Generation of reactive oxygen species (ROS) was associated with dysfunction at the level of mitochondrial complex IV (cytochrome c oxidase, or COX). In neurons cultured from Tg mAPP/ABAD mice, COX activity was selectively decreased, and cyanide, an inhibitor of complex IV, exacerbated leakage of ROS, induction of caspase-3-like activity, and DNA fragmentation. In vivo, Tg mAPP/ABAD mice displayed reduced levels of brain ATP and COX activity, diminished glucose utilization, as well as electrophysiological abnormalities in hippocampal slices compared with Tg mAPP mice. In contrast, neither Tg ABAD mice nor nontransgenic (non-TG) littermates showed similar changes in ATP, COX activity, glucose utilization or electrophysiological properties. Each of the genotypes (Tg ABAD, Tg mAPP and Tg mAPP/ABAD mice, and non-TG littermates) displayed normal reproductive fitness, development and lifespan (1) These findings link ABAD-induced oxidant stress to critical aspects of Alzheimer's disease (AD)-associated cellular dysfunction, suggesting a pivotal role for this enzyme in the pathogenesis of AD.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed2005

High-throughput enzyme assay on a multichannel microchip using optically gated sample introduction.

To meet the requirements for high-throughput screening for drug discovery research, it is very important to develop techniques with the ability of performing multiple enzyme assays simultaneously. Using optically gated sample introduction on a multichannel microchip, multiple enzyme assays have been demonstrated in four parallel channels. The hydrolysis of fluorescein mono-beta-D-galactopyranoside by beta-galactosidase and the inhibition of this reaction by the competitive inhibitor phenylethyl beta-D-thiogalactoside were initially studied to determine the effect of system movement using the voice coil actuator on the enzyme assay reaction. The results from these two studies are consistent with the results from the assay using a single-channel microchip, and they demonstrate that the system using optically gated sample introduction on multichannel microchip can be used to perform multiple enzyme assays. Three unique enzyme assays were also performed in different channels, which show this technique could be competitive for high-throughput screening in drug discovery with other traditional techniques.

Animals↗
PubMed2004

Sample introduction techniques for microfabricated separation devices.

A great deal of progress has been made toward the development of the micro total analysis system (micro-TAS) since its inception in 1990. A wide variety of applications, including genomics, proteomics and drug discovery, have prompted the development of analytical methods capable of very high throughput while maintaining low cost. The micro-TAS concept addresses both of these requirements. Electrophoresis has been a key element in the development of the micro-TAS. Most chemical and biochemical assays utilize a separation component at some point during analysis. Genomics, in particular, depends almost exclusively on electrophoresis for size-based separations of DNA. This review examines sample introduction into microfabricated electrophoretic devices, or chips, primarily for DNA analysis. Sample introduction is an important component of these systems and is an essential process for making chip electrophoresis a widely applicable analytical technique. Specific issues, such as automation, the delivery of large numbers of samples to microfabricated devices and injection of picoliter-sized sample plugs into a separation lanes on chips, are presented.

DNA↗
PubMed2004

Parallel separations of oligonucleotides with optically gated sample introduction on multichannel microchips.

With the release of the human genome sequence, there has been increasing attention given to other genetic analyses, including the detection of genetic variations and fast sequencing of multiple samples for pharmacogenomics studies. Rapid injections of samples in multiplexed separation channels by optically gated sample introduction are shown here for DNA separation. Serial separations of four amino acids are shown in less than four seconds on a microchip with four multiplexed channels. Five short oligonucleotides have also been rapidly separated in 2% LPA with four channels using this technique. In addition, multiple unique samples have been simultaneously separated and five-base resolution has been demonstrated.

4-Chloro-7-nitrobenzofurazan↗
PubMed2003

A rapid enzyme assay for beta-galactosidase using optically gated sample introduction on a microfabricated chip.

The ability to perform enzyme assays on microchips is demonstrated using optically gated sample introduction. The hydrolysis of fluorescein mono- beta- d-galactopyranoside (FMG) by beta- d-galactosidase ( beta-Gal) is continuously monitored using a microchip for 5 to 10 min. The outcome of the reaction was analyzed by performing serial on-chip separations of fluorescent substrate, FMG, and product, fluorescein. Kinetic information about beta-Gal has been successfully obtained by varying the concentration of FMG. beta-Gal enzymes from two different sources including bovine liver and E. coli., have been examined and compared to each other and to results obtained using traditional assay methods. In addition, the competitive inhibition of beta-Gal by phenylethyl beta- d-thiogalactoside (PETG) and beta-lactose has been studied using this technique. PETG is found to have higher inhibition than lactose in the hydrolysis. This separation-based enzyme assay technique avoids the possible fluorescence interference between FMG and fluorescein, which is a problem with the traditional plate assay method. Additionally, the amount of the enzyme and substrate required with this technique is at least four orders of magnitude lower than the traditional plate assay method. By using optically gated sample introduction, microchips allow continuous serial injections and separations without any potential switch, thus making this technique ideal as a sensor for enzyme assays. This technique should therefore be valuable for high-throughput screening in the drug discovery industry.

Fluoresceins↗
PubMed2003

[The relationship of apolipoprotein H G1025C (Try316Ser) polymorphism with stroke and its effect on plasma lipid levels in Changsha Hans].

OBJECTIVE: To investigate the relationship between G1025C (Try316Ser) polymorphism in exon 8 of apolipoprotein H (apoH) gene and stroke and to evaluate the effect of G1025C(Try316Ser) polymorphism on plasma lipid levels in Changsha Hans. METHODS: G1025C (Try316Ser) polymorphism in apoH gene was determined by PCR-single strand conformation polymorphism analysis and DNA sequencing in 100 healthy controls, 260 patients with stroke, and 20 stroke pedigrees. Serum antiphospholipid antibody (APA) levels were tested by enzyme linked immunosorbent assay (ELISA). Plasma lipid levels were measured by routine methods. RESULTS: No statistically significant differences were found in frequencies of genotypes and alleles of G1025C (Try316Ser) polymorphism between the controls and stroke patients. The serum levels of TG in the GC genotype of cerebral infarction patients and controls were markedly higher than those in GG genotype. CONCLUSION: There was no association betweenG1025C (Try316Ser) polymorphism and stroke in Changsha Hans. G1025C (Try316Ser) polymorphism was associated with plasma lipid metabolism in Changsha Hans.

Adult↗
PubMed2002

Parallel analysis with optically gated sample introduction on a multichannel microchip.

As an alternative to the T-type injection on microchips, optically gated sample introduction previously has been demonstrated to provide fast, serial, and reproducible injections on a single-channel microchip. Here, the ability to perform high throughput, multichannel analysis with optically gated sample introduction is described using a voice coil actuator. The microchip is fixed on a stage, which moves back and forth via the voice coil actuator, scanning two laser beams across the channels on the microchip. For parallel analysis on a multichannel microchip, both the gating beam and the probe beam are scanned at 10 Hz to perform multiple injections and parallel detection. Simultaneous, fast separations of 4-choloro-7-nitrobenzofurazan (NBD)-labeled amino acids are demonstrated in multiple channels on a microchip. Serial separations of different samples in multiple channels are also reported. Optically gated sample introduction on multiple, parallel channels shows the potential for high-speed, high-throughput separations that are easily automated by using a single electronic shutter.

4-Chloro-7-nitrobenzofurazan↗
PubMed2002

[Relationship between apolipoprotein H and lipid in stroke patients].

OBJECTIVE: To study the correlation of serum apolipoprotein H (ApoH) with blood lipids and the relationship between ApoH and stroke. METHODS: The serum levels of ApoH of 33 patients with acute cerebral infarction (ACI), 18 patients with acute cerebral hemorrhage (ACH), 17 patients with cerebral apoplexy and family history, and 33 healthy control were measured by radioimmunoassay. The blood lipids of the above mentioned subjects were measured by enzymological methods. RESULTS: The serum ApoH levels in acute cerebral infarction (ACI) patients, acute cerebral hemorrhage (ACH) patients, and healthy controls were 288 +/- 85 mg/L, 248 +/- 68 mg/L, and 256 +/- 71 mg/L respectively. There was a significant correlation between serum ApoH and total CHO and between ApoH and LDL in ACI patients (r = 0.394, P < 0.05; r = 0.394, P < 0.05). However, no correlation between ApoH and triglyceride was found. In 17 cases of cerebral apoplexy with familial history, the serum ApoH was correlated with HDL. CONCLUSION: Serum ApoH is correlated with CHO and LDL in ACI patients. No such correlation can be found in healthy persons and ACH patients.

Aged↗
PubMed2002

[Distribution characteristics of types of stroke in three urban area in China].

OBJECTIVE: To analyze the distribution characteristics of types of stroke in china. METHODS: A prospective study and comprehensive prevention were conducted in urban communities with 300 000 people in Changsha, Beijing and Shanghai, and 2 570 case of stroke at their first occurance were selected with established typing diagnosis (r). RESULTS: Hemmorrhagic, ischemic, and unclassified stroke accounted for 37.1%, 62.3%, and 0.6% respectively. The proportion of hemmorrhagic stroke was more than 50 percent among persons under 50. The average yearly incidence of stroke was 142.3/100 thousand in the intervention areas and was 187.0/100 thousand in the control areas. CONCLUSION: Prevention should be focused on hemorrhagic stroke for those aged over 50 and on ischemic stroke for those aged less than 50. The average incidence rates of hemmorrhagic and of ischemic stroke were lower in the intervention area than in the control area.

Adolescent↗