Biomedical subjects

Lixia Zhang

Publications and source records attributed to Lixia Zhang.

10 recordsLinked to original sources

PubMed2006

Relationship between mutation of IR in the mtr system of Neisseria gonorrhoeae and multiple antibiotic resistance.

To study the relationship between mutation of the inverted repeat sequence (IR) in the multiple transferable resistant system (mtr) of Neisseria gonorrhoeae (NG) and its multiple antibiotic resistance, minimal inhibitory concentrations (MICs) for the clinically isolated strains were tested by agar-dilution-method. The mtr system's IR gene of NG was sequenced after amplification by polymerase chain reaction (PCR). Either two susceptive or five penicillin-resistant strains had no base mutation in IR gene, while all of the 13 strains with multiple-antibiotic-resistance had a single-base deletion (A/T). The result suggests that a single-base deletion of the thirteen-base IR sequence in mtr system of NG might result in multiple antibiotic resistance but is not associated with single antibiotic resistance.

Anti-Infective Agents↗

PubMed2006

Autism spectrum disorders in relation to distribution of hazardous air pollutants in the san francisco bay area.

OBJECTIVE: To explore possible associations between autism spectrum disorders (ASD) and environmental exposures, we linked the California autism surveillance system to estimated hazardous air pollutant (HAP) concentrations compiled by the U.S. Environmental Protection Agency. METHODS: Subjects included 284 children with ASD and 657 controls, born in 1994 in the San Francisco Bay area. We assigned exposure level by census tract of birth residence for 19 chemicals we identified as potential neurotoxicants, developmental toxicants, and/or endocrine disruptors from the 1996 HAPs database. Because concentrations of many of these were highly correlated, we combined the chemicals into mechanistic and structural groups, calculating summary index scores. We calculated ASD risk in the upper quartiles of these group scores or individual chemical concentrations compared with below the median, adjusting for demographic factors. RESULTS: The adjusted odds ratios (AORs) were elevated by 50% in the top quartile of chlorinated solvents and heavy metals [95% confidence intervals (CIs) , 1.1-2.1], but not for aromatic solvents. Adjusting for these three groups simultaneously led to decreased risks for the solvents and increased risk for metals (AORs for metals: fourth quartile = 1.7 ; 95% CI, 1.0-3.0 ; third quartile = 1.95 ; 95% CI, 1.2-3.1) . The individual compounds that contributed most to these associations included mercury, cadmium, nickel, trichloroethylene, and vinyl chloride. CONCLUSIONS: Our results suggest a potential association between autism and estimated metal concentrations, and possibly solvents, in ambient air around the birth residence, requiring confirmation and more refined exposure assessment in future studies.

Air Pollutants↗

PubMed2005

Women's programs versus mixed-gender day treatment: results from a randomized study.

AIMS: To compare outcomes and costs of out-patient women's treatment to mixed-gender programs. DESIGN: Randomized clinical trial. SETTING: Northern California (USA). INTERVENTION: Day treatment: one community-based women's program, two mixed-gender community-based programs and one mixed-gender hospital-based program. PARTICIPANTS: Substance-dependent women recruited from the community (n = 122). MEASUREMENTS: Women were interviewed at baseline, at the end of treatment (94% response rate) and at 6 and 12 months post-treatment (100% response rates). Measures included alcohol and drug use, and psychiatric and social problems. Program costs were estimated using the Drug Abuse Treatment Cost Analysis Program. FINDINGS: No significant differences between the women's program and any of the mixed-gender programs were found for psychiatric problem severity, problems with family and friends or rates of drug use at any of the follow-up points. Rates of alcohol abstinence and total abstinence were similar between the women's program and both of the mixed-gender community programs, but were higher at the mixed-gender hospital program. Only one of these results was replicated in the multivariate analysis, with the odds of total abstinence significantly lower for those randomized to the women's program than the mixed-gender hospital program. However, the average cost of a treatment episode was significantly higher at the hospital program than at the women's program (1212 US dollars versus 543 US dollars). CONCLUSIONS: These findings suggest that female substance abusers may be treated as effectively in mixed-gender programs as in women's programs.

Adult↗

PubMed2005

Quinone methide derivatives: important intermediates to DNA alkylating and DNA cross-linking actions.

Induced DNA interstrand cross-links by chemical agents or photoactivation play very important roles for cancer therapy. Several important clinical drugs (e.g. cisplatin, psoralens, and mitomycin C) are known to induce DNA ISC formation, which can disrupt cell maintenance and replication. Among these anti-tumor agents, one mechanism was involved in quinone methide intermediate. Quinone methide derivative has played important roles in organic syntheses as well as in chemical and biological processes. This review is concerned with current efforts of quinone methide derivatives to DNA alkylation and DNA cross-links. The latest advances in this field will be reviewed in this article. The chemical and physical properties of quinone methide derivatives, the interactions between nucleobases and quinone methide derivatives, the reactions with phosphodiester, DNA alkylation and cross-link via quinone methide intermediate action will be discussed.

Alkylating Agents↗

PubMed2004

Zebrafish Dpr2 inhibits mesoderm induction by promoting degradation of nodal receptors.

Nodal proteins, members of the transforming growth factor-beta (TGFbeta) superfamily, have been identified as key endogenous mesoderm inducers in vertebrates. Precise control of Nodal signaling is essential for normal development of embryos. Here, we report that zebrafish dapper2 (dpr2) is expressed in mesoderm precursors during early embryogenesis and is positively regulated by Nodal signals. In vivo functional studies in zebrafish suggest that Dpr2 suppresses mesoderm induction activities of Nodal signaling. Dpr2 is localized in late endosomes, binds to the TGFbeta receptors ALK5 and ALK4, and accelerates lysosomal degradation of these receptors.

Activin Receptors, Type I↗

PubMed2004

Cloning and expression analysis of zebrafish tob1 gene.

Many members of the Btg/Tob family, which possess anti-proliferation activity, have been identified in mammals but their physiological functions are poorly understood. We have identified a zebrafish tob1 gene, which encodes a peptide of 322 amino acids. The expression pattern of zebrafish tob1 during early embryogenesis is examined by RT-PCR and whole-mount in situ hybridization. The maternal tob1 transcript is abundant in fertilized eggs and blastulas. The expression of tob1 ceases during midgastrulation and early segmentation, when it is expressed and restricted to the notochord and somites. On day 2, expression occurs in the pectoral fin bud but not in other tissues. It will be interesting to investigate whether Tob1 is required for controlling cell proliferation during vertebrate embryogenesis.

Amino Acid Sequence↗

PubMed2004

[Mechanism analysis of optimized model of conversion from farmland to forestland in the hill-gully sub-region of Loess Plateau].

Conversion from Farmland to Forestland Program (CFF) is one of the six great ecological forest programs in China. This study covered the CFF model area of the hilly-gully sub-region of loess plateau, and introduced system dynamics and other latest theories and methodologies. Based on the analysis of five modules including that of the site observation of field stations and extensive investigations, and over 10000 original data obtained in the fields of natural science, social science and economics, the operational mechanism of the optimized model was studied. The optimized operational models integrated maximized ecological, economic and social benefits, while sustainability concepts were proposed for typical CFF sites: The Pinus tabulaeformis + Platycladus orientalis + Zanthoxylum spp. + Robinia pseudoacacia model at the eroded flat ridges of the middle reaches of the Yellow River. The result showed that the ecological, economic and social benefits of the optimized model reflected by main indexes were the best or better, and in the other models, either individual one was the best or others were not. From the viewpoint of comprehensive comparison of three great benefits, the optimized model was most excellent, and had eminent difference comparing to other ones through F test. The relationship between ecological and social benefit was eminent positive correlative. Social benefit was the same with economical one at some degrees. The relationship between ecological and economical benefit was more complicated. On the whole, they were positive correlative, but the economical benefit was not the greatest when the ecological one was the greatest. In general, from the viewpoint of largest comprehensive benefit, the three great benefits were not all the best, indicating that the combination of the modules must be reasonable. In order to achieve the ultimate goal of CFF, we must choose the optimized combination of ecological, economical and social benefits, and can't only pursue any one maximum of three great benefits.

China↗

PubMed2002

Expression and allocation of proteins of the exo-endocytotic machinery in U373 glioma cells: similarities to long-term cultured astrocytes.

1. Cultured astrocytes cells release a variety of low and high molecular weight messenger substances and express proteins of the exocytotic pathway including synaptic SNARE proteins. For analyzing the molecular mechanisms of astrocytic messenger release, permanent cell lines with astrocytic properties would provide useful tools. 2. We analyzed the potential of the human malignant astrocytoma-derived cell line U373 MG to express proteins involved in regulated exo- and endocytosis. An immunoblot analysis identified the astrocyte marker glial fibrillary acidic protein, microtubule-associated protein 2, the v-SNAREs VAMP I, VAMP II, and cellubrevin and the t-SNAREs syntaxin I, SNAP-23, and SNAP-25. 3. The cells also express the secretory granule protein secretogranin II. Although secretogranin II immunofluorescence reveals larger fluorescence spots, the majority of the SNARE proteins is associated with smaller organelles. The immunofluorescence is distributed throughout the cytoplasm and accumulates at processes and the growing edges of cells. 4. The organellar association of SNARE proteins was confirmed by heterologous expression of recombinant fusion proteins. Following subcellular fractionation organelles of lower buoyant density carried the majority of VAMP 11. Secretogranin II was associated with organelles of high buoyant density containing a small contribution of VAMP II. 5. The results suggest that U373 MG cells have in common a considerable number of properties with long-term cultured astrocytes rather than with cultured oligodendrocytes or neurons. They contain two types of organelles that can be physically separated and may be employed in the differential release of messengers.

Astrocytes↗

PubMedDate not supplied

Semipreparative separation and determination of eleutheroside E in Acanthopanax giraldii Harms by high-performance liquid chromatography.

A method for the isolation, purification, and determination of eleutheroside E in Acanthopanax giraldii Harms, collected in the Sichuan province (China), is established. The water extraction of A. giraldii Harms is pre-isolated using macroporous adsorption resin (D-101) and a C18 solid-phase extraction cartridge, and the enriched extract is purified to give eleutheroside E (syringaresinol-di-O-beta-D-glucoside; liriodendrin) by semipreparative reversed-phase high-performance liquid chromatography. Structure identification is performed by a comparison of IR, 1H-NMR, 13C-NMR, and electrospray ionization-mass spectrometric data with the literature. The final purity of the compound is 97%. Quantitative determination of eleutheroside E in A. giraldii Harms is performed on a Zorbax SB C18 (150- x 4.6-mm i.d., 5 microm) column. The linear range of eleutheroside E is 4.85-194 mg/L (r = 0.9998), and the average recovery is 99.6-101%. The developed method is simple, reproducible, and easy to operate. It is useful for the evaluation of Acanthopanax giraldii Harms.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Visualizing Internet routing changes.

Today's Internet provides a global data delivery service to millions of end users and routing protocols play a critical role in this service. It is important to be able to identify and diagnose any problems occurring in Internet routing. However, the Internet's sheer size makes this task difficult. One cannot easily extract out the most important or relevant routing information from the large amounts of data collected from multiple routers. To tackle this problem, we have developed Link-Rank, a tool to visualize Internet routing changes at the global scale. Link-Rank weighs links in a topological graph by the number of routes carried over each link and visually captures changes in link weights in the form of a topological graph with adjustable size. Using Link-Rank, network operators can easily observe important routing changes from massive amounts of routing data, discover otherwise unnoticed routing problems, understand the impact of topological events, and infer root causes of observed routing changes.

Algorithms↗