Biomedical subjects

Ping Wu

Publications and source records attributed to Ping Wu.

At least 19 recordsLinked to original sources

PubMed2025

Exploring diagnostic m6A regulators in primary open-angle glaucoma: insight from gene signature and possible mechanisms by which key genes function.

PURPOSE: The purpose of this study was to interrogate the potential role of N6-methyladenosine (m6A) regulators in the process of trabecular meshwork (TM) tissue damage in patients with primary open-angle glaucoma (POAG). METHODS: Firstly, the expression profile of m6A regulators in TM tissues of POAG patients was comprehensively analyzed by bioinformatics analysis; Plasmid transfection and siRNA gene interference were used to enhance or weaken the expression levels of YTHDC2 in human trabecular meshwork cells (HTMCs); Cell migration ability was detected by transwell chamber assay; Immunofluorescence staining assay was used to evaluate the expression of extracellular matrix (ECM) related proteins. RESULTS: Through the analysis of GSE27276 database, 5 m6A regulators with different expression in POAG were screened out. The results of random forest model showed that these 5 m6A regulators exhibited diagnostic potential and were characteristic genes of POAG. All POAG samples could be effectively divided into two groups based on the expression levels of these 5 hub m6A regulators. Immune cell infiltration analysis indicated that the levels of activated CD8+ T cells and regulatory T cells were different in the two subtypes. HTMC oxidative stress cell model and TGF-β2 stimulation cell model were further constructed to verify the expression of the aforementioned hub m6A regulators, and it was found that YTHDC2 mRNA showed the same expression trend in both models. The silencing of YTHDC2 enhanced the migration ability of HTMCs and increased the synthesis ability of ECM. However, when YTHDC2ΔYTH, which lacks the YTH domain, is overexpressed in HTMCs, there is no significant change in the ECM synthesis ability. CONCLUSIONS: The differentially expressed m6A regulators in TM tissues may serve as potential diagnostic biomarkers for POAG. And, in HTMCs, the expression level of YTHDC2 mRNA was changed under oxidative stress or TGF-β2 intervention, and then exerted its regulation on cell migration and ECM synthesis capability through m6A modification, which may be an important part of the disease process of POAG.

Humans↗

PubMed2007

Human fetal neural stem cells grafted into contusion-injured rat spinal cords improve behavior.

Grafted human neural stem cells (hNSCs) may help to alleviate functional deficits resulting from spinal cord injury by bridging gaps, replacing lost neurons or oligodendrocytes, and providing neurotrophic factors. Previously, we showed that primed hNSCs differentiated into cholinergic neurons in an intact spinal cord. In this study, we tested the fate of hNSCs transplanted into a spinal cord T10 contusion injury model. When grafted into injured spinal cords of adult male rats on either the same day or 3 or 9 days after a moderate contusion injury, both primed and unprimed hNSCs survived for 3 months postengraftment only in animals that received grafts at 9 days postinjury. Histological analyses revealed that primed hNSCs tended to survive better and differentiated at higher rates into neurons and oligodendrocytes than did unprimed counterparts. Furthermore, only primed cells gave rise to cholinergic neurons. Animals receiving primed hNSC grafts on the ninth day postcontusion improved trunk stability, as determined by rearing activity measurements 3 months after grafting. This study indicates that human neural stem cell fate determination in vivo is influenced by the predifferentiation stage of stem cells prior to grafting. Furthermore, stem cell-mediated facilitation of functional improvement depends on the timing of transplantation after injury, the grafting sites, and the survival of newly differentiated neurons and oligodendrocytes.

Animals↗

PubMed2006

Effectiveness of smoking cessation therapies: a systematic review and meta-analysis.

BACKGROUND: Smoking remains the leading preventable cause of premature deaths. Several pharmacological interventions now exist to aid smokers in cessation. These include Nicotine Replacement Therapy [NRT], bupropion, and varenicline. We aimed to assess their relative efficacy in smoking cessation by conducting a systematic review and meta-analysis. METHODS: We searched 10 electronic medical databases (inception to Sept. 2006) and bibliographies of published reviews. We selected randomized controlled trials [RCTs] evaluating interventions for smoking cessation at 1 year, through chemical confirmation. Our primary endpoint was smoking cessation at 1 year. Secondary endpoints included short-term smoking cessation (approximately 3 months) and adverse events. We conducted random-effects meta-analysis and meta-regression. We compared treatment effects across interventions using head-to-head trials and when these did not exist, we calculated indirect comparisons. RESULTS: We identified 70 trials of NRT versus control at 1 year, Odds Ratio [OR] 1.71, 95% Confidence Interval [CI], 1.55-1.88, P =< 0.0001). This was consistent when examining all placebo-controlled trials (49 RCTs, OR 1.78, 95% CI, 1.60-1.99), NRT gum (OR 1.60, 95% CI, 1.37-1.86) or patch (OR 1.63, 95% CI, 1.41-1.89). NRT also reduced smoking at 3 months (OR 1.98, 95% CI, 1.77-2.21). Bupropion trials were superior to controls at 1 year (12 RCTs, OR1.56, 95% CI, 1.10-2.21, P = 0.01) and at 3 months (OR 2.13, 95% CI, 1.72-2.64). Two RCTs evaluated the superiority of bupropion versus NRT at 1 year (OR 1.14, 95% CI, 0.20-6.42). Varenicline was superior to placebo at 1 year (4 RCTs, OR 2.96, 95% CI, 2.12-4.12, P =< 0.0001) and also at approximately 3 months (OR 3.75, 95% CI, 2.65-5.30). Three RCTs evaluated the effectiveness of varenicline versus bupropion at 1 year (OR 1.58, 95% CI, 1.22-2.05) and at approximately 3 months (OR 1.61, 95% CI, 1.16-2.21). Using indirect comparisons, varenicline was superior to NRT when compared to placebo controls (OR 1.66, 95% CI 1.17-2.36, P = 0.004) or to all controls at 1 year (OR 1.73, 95% CI 1.22-2.45, P = 0.001). This was also the case for 3-month data. Adverse events were not systematically different across studies. CONCLUSION: NRT, bupropion and varenicline all provide therapeutic effects in assisting with smoking cessation. Direct and indirect comparisons identify a hierarchy of effectiveness.

Benzazepines↗

PubMed2006

Magnesium enhances aluminum-induced citrate secretion in rice bean roots (Vigna umbellata) by restoring plasma membrane H+-ATPase activity.

We demonstrated that magnesium (Mg) can alleviate aluminum (Al) toxicity in rice bean [Vigna umbellata (Thunb.) Ohwi & Ohashi] more effectively than is expected from a non-specific cation response. Micromolar concentrations of Mg alleviated the inhibition of root growth by Al but not by lanthanum, and neither strontium nor barium at the micromolar level alleviates Al toxicity. Aluminum also induced citrate efflux from rice bean roots, and this response was stimulated by inclusion of 10 microM Mg in the treatment solution. The increase in the Al-induced citrate efflux by Mg paralleled the improvement in root growth, suggesting that the ameliorative effect of Mg might be related to greater citrate efflux. Vanadate (an effective H+-ATPase inhibitor) decreased the Al-induced citrate efflux, while addition of Mg partly restored the efflux. Mg addition also increased the activity of Al-reduced plasma membrane H+-ATPase, as well as helping to maintain the Mg and calcium contents in root apices. We propose that the addition of Mg to the toxic Al treatment helps maintain the tissue Mg content and the activity of the plasma membrane H+-ATPase. These changes enhanced the Al-dependent efflux of citrate which provided extra protection from Al stress.

Aluminum↗

PubMed2006

Epidemiology and reporting of randomized trials employing re-randomization of patient groups: a systematic survey.

Trials employing re-randomization of some or all participants provide opportunities for determining optimal dosing and dosing schedules, potential disease modifying effects, direct comparisons between drugs, and salvage therapy for patients failing their assigned treatments. To date, no data exists about their prevalence, epidemiology, or quality. We undertook a systematic review of all trials re-randomizing patients. Using explicit search criteria, we searched 11 electronic databases independently, in duplicate. We additionally searched pharmaceutical company websites for unpublished studies. We extracted data on the epidemiology of trials, year published, characteristics of the purpose of the re-randomization, what groups of patients were re-randomized, and methodological issues, including allocation, concealment, sequence generation, blinding, intention to treat, and appropriate sample size calculations. We found 65 trials. All trials were reported in English. Of these, 21 employed re-randomization to determine optimal dosing, 8 for optimal dose-scheduling, 3 for salvage therapy, 0 for estimating disease modifying effects, 24 as direct comparison trials, 9 as standard efficacy trials--that did not require re-randomization, and 3 as withdrawal of treatment trials. The median sample size of the period prior to re-randomization is 180 [interquartile range (IQR) 83-480] and after re-randomization is 104 [IQR 36 to 246]. Studies lost a median of 8% of eligible patients from period 1 to period 2 [IQR 0 to 17]. Studies were published between 1975 and 2005, with the vast majority (71%) published since 1995. The findings of our review indicate that trials employing re-randomization are relatively rare, have poor reporting of important methodological features, and, in some circumstances, fail to take advantage of the benefits that re-randomization can permit.

Dose-Response Relationship, Drug↗

PubMed2006

Transplantation of primed human fetal neural stem cells improves cognitive function in rats after traumatic brain injury.

Traumatic brain injury (TBI) often produces cognitive impairments by primary or secondary neuronal loss. Stem cells are a potential tool to treat TBI. However, most previous studies using rodent stem or progenitor cells failed to correlate cell grafting and cognitive improvement. Furthermore, the efficacy of fetal human neural stem cells (hNSCs) for ameliorating TBI cognitive dysfunction is undetermined. This study therefore characterized phenotypic differentiation, neurotrophic factor expression and release and functional outcome of grafting hNSCs into TBI rat brains. Adult Sprague-Dawley rats underwent a moderate parasagittal fluid percussion TBI followed by ipsilateral hippocampal transplantation of hNSCs or vehicle 1 day post-injury. Prior to grafting, hNSCs were treated in vitro for 7 days with our previously developed priming procedure. Significant spatial learning and memory improvements were detected by the Morris water maze (MWM) test in rats 10 days after receiving hNSC grafts. Morphological analyses revealed that hNSCs survived and differentiated mainly into neurons in the injured hippocampus at 2 weeks after grafting. Furthermore, hNSCs expressed and released glial-cell-line-derived neurotrophic factor (GDNF) in vitro and when grafted in vivo, as detected by RT-PCR, immunostaining, microdialysis and ELISA. This is the first direct demonstration of the release of a neurotrophic factor in conjunction with stem cell grafting. In conclusion, human fetal neural stem cell grafts improved cognitive function of rats with acute TBI. Grafted cells survived and differentiated into neurons and expressed and released GNDF in vivo, which may help protect host cells from secondary damage and aid host regeneration.

Animals↗

PubMed2006

Adherence to antiretroviral therapy in sub-Saharan Africa and North America: a meta-analysis.

CONTEXT: Adherence to antiretroviral therapy is a powerful predictor of survival for individuals living with human immunodeficiency virus (HIV) and AIDS. Concerns about incomplete adherence among patients living in poverty have been an important consideration in expanding the access to antiretroviral therapy in sub-Saharan Africa. OBJECTIVE: To evaluate estimates of antiretroviral therapy adherence in sub-Saharan Africa and North America. DATA SOURCES: Eleven electronic databases were searched along with major conference abstract databases (inclusion dates: inception of database up until April 18, 2006) for all English-language articles and abstracts; and researchers and treatment advocacy groups were contacted. Study Selection and Data Abstraction To best reflect the general population, studies of mixed populations in both North America and Africa were selected. Studies evaluating specific populations such as men only, homeless individuals, or drug users, were excluded. The data were abstracted in duplicate on study adherence outcomes, thresholds used to determine adherence, and characteristics of the populations. A random-effects meta-analysis was performed in which heterogeneity was examined using multivariable random-effects logistic regression. A sensitivity analysis was performed using Bayesian methods. DATA SYNTHESIS: Thirty-one studies from North America (28 full-text articles and 3 abstracts) and 27 studies (9 full-text articles and 18 abstracts) from sub-Saharan Africa were included. African studies represented 12 sub-Saharan countries. Of the North American studies, 71% used patient self-report to assess adherence; this was true of 66% of the African assessments. Studies reported similar thresholds for adherence monitoring (eg, 100%, >95%, >90%, >80%). A pooled analysis of the North American studies (17,573 patients total) indicated a pooled estimate of 55% (95% confidence interval, 49%-62%; I2, 98.6%) of the populations achieving adequate levels of adherence. Our pooled analysis of African studies (12,116 patients total) indicated a pooled estimate of 77% (95% confidence interval, 68%-85%; I2, 98.4%). Study continent, adherence thresholds, and study quality were significant predictors of heterogeneity. Bayesian analysis was used as an alternative statistical method for combining adherence rates and provided similar findings. CONCLUSION: Our findings indicate that favorable levels of adherence, much of which was assessed via patient self-report, can be achieved in sub-Saharan African settings and that adherence remains a concern in North America.

Africa South of the Sahara↗

PubMed2006

Cytokinin-mediated cell cycling arrest of pericycle founder cells in lateral root initiation of Arabidopsis.

In Arabidopsis, lateral root formation is a post-embryonic developmental event, which is regulated by hormones and environmental signals. In this study, via analyzing the expression of cyclin genes during lateral root (LR) formation, we report that cytokinins (CTKs) inhibit the initiation of LR through blocking the pericycle founder cells cycling at the G(2) to M transition phase, while the promotion by CTK of LR elongation is due to the stimulation of the G(1) to S transition. No significant difference was detected in the inhibitory effect of CTK on LR formation between wild-type plants and mutants defective in auxin response or transport. In addition, exogenously applied auxin at different concentrations could not rescue the CTK-mediated inhibition of LR initiation. Our data suggest that CTK and auxin might control LR initiation through two separate signaling pathways in Arabidopsis. The CTK-mediated repression of LR initiation is transmitted through the two-component signal system and mediated by the receptor CRE1.

Arabidopsis↗

PubMed2006

The hpa1 mutant of Arabidopsis reveals a crucial role of histidine homeostasis in root meristem maintenance.

Histidine (His) is an essential ingredient for protein synthesis and is required by all living organisms. In higher plants, although there is considerable evidence that His is essential for plant growth and survival, there is very little information as to whether it plays any specific role in plant development. Here, we present evidence for such a role of this amino acid in root development in Arabidopsis (Arabidopsis thaliana) from the characterization of a novel Arabidopsis mutant, hpa1, which has a very short root system and carries a mutation in one of the two Arabidopsis histidinol-phosphate aminotransferase (HPA) genes, AtHPA1. We have established that AtHPA1 encodes a functional HPA and that its complete knockout is embryo lethal. Biochemical analysis shows that the mutation in hpa1 only resulted in a 30% reduction in free His content and had no significant impact on the total His content. It did not cause any known symptoms of His starvation. However, the mutant displayed a specific developmental defect in root meristem maintenance and was unable to sustain primary root growth 2 d after germination. We have demonstrated that the root meristem failure in the mutant is tightly linked to the reduction in free His content and could be rescued by either exogenous His supplementation or AtHPA1 overexpression. Our results therefore reveal an important role of His homeostasis in plant development.

Amino Acid Sequence↗

PubMed2006

Comparative structural analysis of the Erbin PDZ domain and the first PDZ domain of ZO-1. Insights into determinants of PDZ domain specificity.

We report a structural comparison of the first PDZ domain of ZO-1 (ZO1-PDZ1) and the PDZ domain of Erbin (Erbin-PDZ). Although the binding profile of Erbin-PDZ is extremely specific ([D/E][T/S]WV(COOH)), that of ZO1-PDZ1 is similar ([R/K/S/T][T/S][W/Y][V/I/L](COOH)) but broadened by increased promiscuity for three of the last four ligand residues. Consequently, the biological function of ZO-1 is also broadened, as it interacts with both tight and adherens junction proteins, whereas Erbin is restricted to adherens junctions. Structural analyses reveal that the differences in specificity can be accounted for by two key differences in primary sequence. A reduction in the size of the hydrophobic residue at the base of the site(0) pocket enables ZO1-PDZ1 to accommodate larger C-terminal residues. A single additional difference alters the specificity of both site(-1) and site(-3). In ZO1-PDZ1, an Asp residue makes favorable interactions with both Tyr(-1) and Lys/Arg(-3). In contrast, Erbin-PDZ contains an Arg at the equivalent position, and this side chain cannot accommodate either Tyr(-1) or Lys/Arg(-3) but, instead, interacts favorably with Glu/Asp(-3). We propose a model for ligand recognition that accounts for interactions extending across the entire binding site but that highlights several key specificity switches within the PDZ domain fold.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Plant nutriomics in China: an overview.

BACKGROUND: Population and environmental pressure have imposed a great challenge on agriculture in China to explore innovative and effective solutions to its pressing plant nutritional problems. Plant nutriomics is a new frontier in plant biology that can provide innovative solutions for improving plant nutrient efficiency, thus increasing crop productivity through genetic and molecular approaches. SCOPE: This review summarizes current efforts and progress in plant nutriomic research in China with examples from several case studies. It also points out potential obstacles and depicts future perspectives in this emerging frontier of plant nutrition. CONCLUSIONS: Although plant nutriomics is still at a conceptual stage, substantial efforts are being made in China aimed at increasing plant nutrient efficiency through a nationwide, co-ordinated project on plant nutriomics. Future studies involving both national and international collaborations are needed to develop nutrient-efficient, stress-tolerant and high-quality crop varieties for both China and elsewhere.

Boron↗

PubMed2006

Novel cycloaddition reaction of [60]fullerene with carbonyl ylides generated from epoxides.

The thermal reaction of [60]fullerene (C60) with the carbonyl ylides generated in situ from trans-epoxides to give C60-fused tetrahydrofuran derivatives has been investigated. The reaction of C60 with trans-2-benzoyl-3-aryloxiranes afforded only cis-products, while the reaction of C60 with 2-cyano-2-ethoxycarbonyl-3-aryloxiranes gave exclusively or predominantly cis isomers. The isomeric distributions of the latter reactions were drastically affected by the substituent on the phenyl ring.

Epoxy Compounds↗

PubMed2006

ANIT toxicity toward mouse hepatocytes in vivo is mediated primarily by neutrophils via CD18.

Alpha-naphthylisothiocyanate (ANIT) is a hepatotoxicant that causes acute cholestatic hepatitis with infiltration of neutrophils around bile ducts and necrotic hepatocytes. The objective of this study was to determine whether the beta2-integrin CD18, which plays an important role in leukocyte invasion and cytotoxicity, contributes to ANIT-induced hepatic inflammation and liver injury. Mice with varying levels of leukocyte CD18 expression were treated with ANIT and monitored for hepatic neutrophil influx and liver injury over 48 h. Mice that were partially deficient in CD18 (30% of normal levels) developed periportal inflammation and widespread hepatic necrosis after ANIT treatment in a pattern identical to that in wild-type (WT) mice. In contrast, mice that completely lack CD18 (CD18 null) were resistant to ANIT toxicity. Forty-eight hours after ANIT, CD18-null mice displayed 60% lower serum alanine aminotransferase (ALT) levels and 75% less hepatic necrosis, as shown by morphometry, than WT mice. This was true despite evidence that ANIT still provoked hepatic neutrophil influx in CD18-null mice. WT mice could also be protected from ANIT-induced hepatocellular necrosis, by depleting the animals of neutrophils. Notably, neither CD18-null mice nor neutrophil-depleted WT mice exhibited any attenuation of bile duct injury or cholestasis due to ANIT. We conclude from these experiments that neutrophils invade ANIT-treated livers in a CD18-independent fashion but utilize CD18 to induce hepatocellular cytotoxicity. The results emphasize that neutrophil-mediated amplification of ANIT-induced liver injury is directed toward hepatocytes rather than cholangiocytes. In fact, the data indicate that the majority of ANIT toxicity toward hepatocytes in vivo is neutrophil driven.

1-Naphthylisothiocyanate↗

PubMed2006

Exposure to the World Trade Center attack and the use of cigarettes and alcohol among New York City public high-school students.

We examined exposure to the World Trade Center attack and changes in cigarette smoking and drinking among 2731 New York City public high-school students evaluated 6 months after the attack. Increased drinking was associated with direct exposure to the World Trade Center attack (P < .05). Increased smoking was not directly associated with exposure to the World Trade Center attack but was marginally significantly associated with posttraumatic stress disorder (P= .06). Our findings suggest that targeted substance-use interventions for youths may be warranted after large-scale disasters.

Adolescent↗

PubMed2006

Citrate transporters play a critical role in aluminium-stimulated citrate efflux in rice bean (Vigna umbellata) roots.

BACKGROUND AND AIMS: Aluminium (Al) stimulates the efflux of citrate from apices of rice bean (Vigna umbellata) roots. This response is delayed at least 3 h when roots are exposed to 50 microm Al, indicating that some inducible processes leading to citrate efflux are involved. The physiological bases responsible for the delayed response were examined here. METHODS: The effects of several antagonists of anion channels and citrate carriers, and of the protein synthesis inhibitor, cycloheximide (CHM) on Al-stimulated citrate efflux and/or citrate content were examined by high-pressure liquid chromatography (HPLC) or an enzymatic method. KEY RESULTS: Both anion channel inhibitors and citrate carrier inhibitors can inhibit Al-stimulated citrate efflux, with anthracene-9-carboxylic acid (A-9-C, an anion channel inhibitor) and phenylisothiocyanate (PI, a citrate carrier inhibitor) the most effective inhibitors. A 6 h pulse of 50 microm Al induced a significant increase of citrate content in root apices and release of citrate. However, the increase in citrate content preceded the efflux. Furthermore, the release of citrate stimulated by the pulse treatment was inhibited by both A-9-C and PI, indicating the importance of the citrate carrier on the mitochondrial membrane and the anion channel on the plasma membrane for the Al-stimulated citrate efflux. CHM (20 microm) also significantly inhibited Al-stimulated citrate efflux, confirming that de novo protein synthesis is required for Al-stimulated citrate efflux. CONCLUSIONS: These results indicate that the activation of genes possibly encoding citrate transporters plays a critical role in Al-stimulated citrate efflux.

Aluminum↗

PubMed2006

Morphoregulation of avian beaks: comparative mapping of growth zone activities and morphological evolution.

Avian beak diversity is a classic example of morphological evolution. Recently, we showed that localized cell proliferation mediated by bone morphogenetic protein 4 (BMP4) can explain the different shapes of chicken and duck beaks (Wu et al. [2004] Science 305:1465). Here, we compare further growth activities among chicken (conical and slightly curved), duck (straight and long), and cockatiel (highly curved) developing beak primordia. We found differential growth activities among different facial prominences and within one prominence. The duck has a wider frontal nasal mass (FNM), and more sustained fibroblast growth factor 8 activity. The cockatiel has a thicker FNM that grows more vertically and a relatively reduced mandibular prominence. In each prominence the number, size, and position of localized growth zones can vary: it is positioned more rostrally in the duck and more posteriorly in the cockatiel FNM, correlating with beak curvature. BMP4 is enriched in these localized growth zones. When BMP activity is experimentally altered in all prominences, beak size was enlarged or reduced proportionally. When only specific prominences were altered, the prototypic conical shaped chicken beaks were converted into an array of beak shapes mimicking those in nature. These results suggest that the size of beaks can be modulated by the overall activity of the BMP pathway, which mediates the growth. The shape of the beaks can be fine-tuned by localized BMP activity, which mediates the range, level, and duration of locally enhanced growth. Implications of topobiology vs. molecular blueprint concepts in the Evo-Devo of avian beak forms are discussed.

Animals↗

PubMed2006

Posttraumatic stress in children with first responders in their families.

High levels of exposure and occupational stress of first responders may have caused children in first-responder families to become traumatized following the September 11th, 2001 terrorist attacks. New York City public school children (N = 8,236) participated in a study examining mental health problems 6 months after the World Trade Center attack. Results revealed that children with emergency medical technician (EMT) family members had a high prevalence of probable posttraumatic stress disorder (PTSD; 18.9%). Differences in rates of probable PTSD among EMTs' and firefighters' children were explained by demographic characteristics. Where EMTs are drawn from disadvantaged groups, one implication of this study is to target EMT families in any mental health interventions for children of first responders.

Adolescent↗

PubMed2006

Study of automated mass spectral deconvolution and identification system (AMDIS) in pesticide residue analysis.

The effects of overlapping levels and concentration ratios of overlapping components, and of scan rates of the mass spectrometer, on the capability of the automated mass spectral deconvolution and identification system (AMDIS) in pesticide residue analysis were studied. To investigate the capability of AMDIS in removing interferences from the overlapping peaks, this system was applied to data files obtained from the gas chromatography/mass spectrometry (GC/MS) analysis of two overlapping (co-eluting) pesticides (beta-HCH and PCNB) in full scan mode. Differences in overlap levels, the concentration ratios of the two overlapping components and the scan rates of the instrument were studied. When the difference in scan number of overlapping compounds was equal to 1 scan, AMDIS incompletely extracted 'purified' mass spectra but as the difference increased to 3 or more scans, complete correct spectra could be extracted. The results also show that when the scan rate was in the range of 0.4-0.90 s/scan and the concentration ratios of the target compound/interference were above 1/5, there were ideal deconvolution results for this approach. To further study the application of AMDIS to pesticide residue analysis, AMDIS was applied to the identification of pesticides spiked in real samples (cabbage and rice). Typical pesticides being evaluated were identified using AMDIS at concentrations >50 ng/g in the extracts.

Brassica↗