Journal of Exposure Analysis and Environmental Epidemiology最新文献

{"title":"Collecting urine samples from young children using cotton gauze for pesticide studies.","authors":"Y A Hu,&nbsp;D B Barr,&nbsp;G Akland,&nbsp;L Melnyk,&nbsp;L Needham,&nbsp;E D Pellizzari,&nbsp;J H Raymer,&nbsp;J M Roberds","doi":"10.1038/sj.jea.7500134","DOIUrl":"https://doi.org/10.1038/sj.jea.7500134","url":null,"abstract":"<p><p>To estimate pesticide exposure, urine samples are often needed to analyze pesticide metabolites. However, this is difficult for children wearing diapers because simple and feasible techniques suitable for field collection are not available. The objectives of this study were to test the validity of using cotton gauze pad as a medium for collecting urine samples from young children and to examine the stability of the recoveries for creatinine and pesticide metabolites over 24 h. Urine spiked with a pesticide and four metabolites, 2,4-dichlorophenoxyacetic acid (which is mainly eliminated from urine unchanged), 3-phenoxybenzoic acid (metabolite for synthetic pyrethroids), atrazine mercapturate (metabolite for atrazine), malathion dicarboxylic acid (metabolite for malathion), and 2-isopropyl-4-methyl-6-hydroxypyrimidine (metabolite for diazinon) was added to the gauze pads and kept in jars at 37 degrees C in a water bath. Urine was expressed from the gauze pads immediately and after 1, 2, 4, 8, and 24 h, then analyzed. The recoveries, calculated as the percentage of concentration in expressed urine divided by that of the control urine sample, were within a range of 70-130%. The metabolite and creatinine concentrations did not change with time in either expressed urine samples or controls. The results suggest that cotton gauze pad is a promising candidate for collecting urine samples from young children wearing diapers for studies in which these five urinary pesticide metabolites are to be analyzed.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"703-9"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500134","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21960425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Factors influencing total dietary exposures of young children.","authors":"G G Akland,&nbsp;E D Pellizzari,&nbsp;Y Hu,&nbsp;M Roberds,&nbsp;C A Rohrer,&nbsp;J O Leckie,&nbsp;M R Berry","doi":"10.1038/sj.jea.7500129","DOIUrl":"https://doi.org/10.1038/sj.jea.7500129","url":null,"abstract":"<p><p>A deterministic model was developed to identify the critical input parameters needed to assess dietary intakes of young children. The model was used as a framework for understanding the important factors in data collection and data analysis. Factors incorporated into the model included transfer efficiencies of pesticide from surfaces to food, transfer efficiencies of pesticide from surfaces to hands to food, and more accurate microactivity data related to contact frequency for the three variables of interest--hands, surfaces, and food. Results from range-finding measurements of transfer efficiencies using an aqueous pesticide solution of a mixture of malathion, diazinon, and chlorpyrifos sprayed on the surfaces indicate that a higher pesticide transfer occurred from hard surfaces to food (hardwood, plastic), with low transfer from soft surfaces (carpet, cloth). Six children, all less than 4 years old, were videotaped to obtain realistic contact frequency and times for the interaction of hands, surfaces, and foods during eating meals and snacks while in their homes or day care centers. The time range of eating events varied from about 2 to 55 min, with an average of about 20 min. The average number of contact frequencies between food and hands was 19 times for each eating event, with a range of 10-40. Contacts between the surface and hand were about the same as the food and hands. Contacts between foods and surfaces ranged from 0 to 32, but only five or less of the contacts per eating event were associated with surfaces other than eating utensil. The children's microactivity data collected during the eating events, together with the laboratory results from the transfer studies, were provided as input into a Monte Carlo simulation of the dietary ingestion model. Simulation results indicate that children's handling of the food could contribute 20-80% of the total dietary intake of pesticides. Dietary exposure due to residues in the food before handling accounted for 16% and 47%, respectively, of the total mean intake from simulations for a child's consumption of an apple or banana. These results indicated that transfer efficiencies for foods on various surfaces typically found in homes as well as children's hand contacts with the food and surfaces are important as determinants of dietary exposure.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"710-22"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500129","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21960422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HPLC-MS/MS method for the measurement of seven phytoestrogens in human serum and urine.","authors":"L Valentín-Blasini,&nbsp;B C Blount,&nbsp;H S Rogers,&nbsp;L L Needham","doi":"10.1038/sj.jea.7500122","DOIUrl":"https://doi.org/10.1038/sj.jea.7500122","url":null,"abstract":"<p><p>The elevated exposure of children to hormonally active dietary phytoestrogens has led to the need for rapid, sensitive, and precise assays for phytoestrogen metabolites in physiological matrices. Here we report the development of a high-performance liquid chromatography (HPLC) MS/MS method for the quantitative detection of seven phytoestrogens in human serum and urine. The method uses enzymatic deconjugation of the phytoestrogen metabolites followed by solid phase extraction (SPE) and reverse-phase HPLC. The phytoestrogens are detected using a Sciex API III heated nebulizer atmospheric pressure chemical ionization (HN-APCI) interface coupled with tandem mass spectrometry. This method allows the detection of the primary dietary phytoestrogens (isoflavones and lignans) in human serum and urine with limits of detection (LODs) in the low parts per billion range. The combination of tandem mass spectrometry and chromatographic separation of the analytes helps ensure the selectivity of the method. Stable isotope-labeled internal standards for all seven analytes improve the precision of the assay, resulting in interday CV values of < 10% for most compounds studied. The accuracy and precision of the method were monitored over time using quality control (QC) samples containing known amounts of phytoestrogens. The majority of phytoestrogens in human sera and urine are present as their glucuronide and sulfate conjugates. Therefore, the thoroughness of deconjugation for each sample was monitored by the addition of a conjugated internal standard and subsequent detection of deconjugated compound. This method proves to be efficacious for measuring baseline urinary phytoestrogen levels in the American population and should prove useful for assessing the modulatory effects of dietary phytoestrogens on endocrine disrupter action in children.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"799-807"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500122","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21961634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using observational information in planning and implementation of field studies with children as subjects.","authors":"B Buckley,&nbsp;A Ettinger,&nbsp;P Hore,&nbsp;P Lioy,&nbsp;N Freeman","doi":"10.1038/sj.jea.7500127","DOIUrl":"https://doi.org/10.1038/sj.jea.7500127","url":null,"abstract":"<p><p>Children have been one of the least-studied populations for estimating environmental exposure, even though they are cited as a sensitive subgroup for diseases derived from environmental exposure. This trend appears to be changing as more studies are conducted with children as subjects. It consequently becomes increasingly important to gather and use observational data in all phases of the study. Observational data are the key for both defining the pathway of exposure and for assessing effectiveness of the data-collection protocols. Obtaining quality data from a study involving children requires: efficient use of observational data, collection of meaningful personal and microenvironmental samples, linkage of observational data to the collected samples, and personnel trained to work with children using pilot-tested protocols. Although all of these help to ensure the quality of the data, the utility of the data is often determined by observational feedback from those who collected it. Laboratory-derived protocols should be living documents and observations from the field should be used to modify the data-collection methods when practical.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"695-702"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500127","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21960420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Utilization of umbilical cords to assess in utero exposure to persistent pesticides and polychlorinated biphenyls.","authors":"V W Burse,&nbsp;A R Najam,&nbsp;C C Williams,&nbsp;M P Korver,&nbsp;B F Smith,&nbsp;P M Sam,&nbsp;S L Young,&nbsp;L L Needham","doi":"10.1038/sj.jea.7500125","DOIUrl":"https://doi.org/10.1038/sj.jea.7500125","url":null,"abstract":"<p><p>In support of a study to relate developmental and cognitive effects with prenatal exposure to selected environmental toxicants, we developed and applied an analytical method to determine the concentration of two persistent pesticides, hexachlorobenzene (HCB) and p,p'-dichlorodiphenyldichloroethylene (DDE), and 32 specific polychlorinated biphenyl (PCB) congeners in 316 umbilical cords taken in 1986-1987 from women of the Faroe Islands. The analytical method consisted of homogenization of the cords, partitioning, microsilica gel column chromatography for clean-up, and dual-column capillary gas chromatography (DB-5 and DB-1701) with electron capture detection. Several quality control parameters were followed to monitor the performance of the method. Important criteria used before reporting unknown data were the recovery of in vitro-spiked analytes from a bovine umbilical cord (BUC) and the percentage lipid obtained for a Certified Reference Material (CRM)-350 of mackerel oil (MO). Recoveries of analytes that had been spiked at two concentration ranges (0.26-0.95 ng/g whole weight; 0.35-2.42 ng/g whole weight) into bovine cords ranged from 38.5% to 158% and from 50.4% to 145%, respectively, with a median recovery of 77.7%. Measurement of the percentage lipid for CRM-350 ranged from 73.8% to 107% with a median lipid value of 96.0%. The most prevalent analytes detected (%) in unknown umbilical cords were HCB (100), DDE (100), Ballschmiter/Zell PCBs 153 (100), 138 (98), 180 (98), 170 (93), 118 (88), 187 (86), and 146 (83), with corresponding median concentrations (ng/g whole weight) of 0.17, 1.19, 0.38, 0.30, 0.17, 0.11, 0.12, 0.09, and 0.07, respectively. Total PCB--sum of all measurable PCB congeners--had a median concentration of 1.37 ng/g whole weight. The analytes, which were very low in lipid content were also quantified on a lipid-adjusted basis, which provided an analytical challenge in these umbilical cord samples. The gravimetrically measured lipids in the human specimens ranged from 0.01% to 1.43% (median of 0.18%). In the pooled BUCs, our lipid measurements varied from 0.05% to 0.33% with a median value of 0.13%. The utility of using the umbilical cord as a matrix to assess in utero exposure to persistent environmental pollutants, compared with the use of umbilical cord blood or mother's blood, is worthy of debate.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"776-88"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500125","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21961631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The National Institute of Environmental Health Sciences' research program on children's environmental health.","authors":"L R O'Fallon,&nbsp;G W Collman,&nbsp;A Dearry","doi":"10.1038/sj.jea.7500117","DOIUrl":"https://doi.org/10.1038/sj.jea.7500117","url":null,"abstract":"<p><p>This article highlights the wide array of research programs supported by the National Institute of Environmental Health Sciences (NIEHS) that address issues related to children's environmental health. Special attention is given to the interagency, collaborative Centers for Children's Environmental Health and Disease Prevention Research program. A brief description of each of the eight centers highlights scientific foci and research efforts to date. In addition to discussing NIEHS-supported research programs, the article emphasizes the NIEHS' commitment to the promotion of translating basic research findings into public health knowledge so that culturally sensitive and applicable interventions may be developed.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"630-7"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500117","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measuring developmental outcomes of lead exposure in an urban neighborhood: the challenges of community-based research.","authors":"C Jordan,&nbsp;P Lee,&nbsp;E Shapiro","doi":"10.1038/sj.jea.7500130","DOIUrl":"https://doi.org/10.1038/sj.jea.7500130","url":null,"abstract":"<p><p>The Developmental Research on Attention and Memory Skills (DREAMS) Project measures developmental outcomes of approximately 330 children at risk for lead exposure within an ethnically diverse, inner-city neighborhood. This study is one project of the Phillips Neighborhood Healthy Housing Collaborative, a 6-year-old collaboration between residents of the Phillips community in Minneapolis, university researchers, and representatives of various public and private agencies. Our experience carrying out this research is used to highlight both the benefits of, and the challenges to, measuring exposure outcomes in inner-city children using a community-based research approach. Challenges to working within a community collaborative, to studying an ethnically diverse and economically disadvantaged neighborhood, and to utilizing neighborhood residents as project staff are discussed. The strategies used to address these issues are presented to offer ideas for surmounting the challenges inherent in community-based research. The investigation of community environmental health problems through a community-based research approach can result in improved methodology, enhanced quality of data collected, and increased effectiveness of data dissemination. In addition, it can lead to important findings that inform the scientific community and create positive community changes. It is paramount, however, that potential obstacles be anticipated and planned for, or else be detected early and promptly responded to, in a manner that preserves scientific rigor while respecting community needs and values.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"732-42"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500130","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21960424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing children's exposure to hazardous environmental chemicals: an overview of selected research challenges and complexities.","authors":"L L Needham,&nbsp;K Sexton","doi":"10.1038/sj.jea.7500142","DOIUrl":"https://doi.org/10.1038/sj.jea.7500142","url":null,"abstract":"<p><p>There is renewed interest in the United States regarding characterization of children's exposures to hazardous environmental chemicals. Many studies are currently underway that use novel and innovative approaches to assess childhood exposures to a variety of toxic chemicals, including both persistent and nonpersistent compounds. This article reviews some of the critical challenges that can impede scientifically rigorous studies designed to measure children's environmental exposures. The discussion briefly examines three topical areas: administrative issues (IRB approval, participant incentives, community involvement, and communication of results to research participants and stakeholders); data-collection issues (identifying and recruiting children/families, measuring actual exposures/doses); and issues related to chemical analysis of biological samples (examples of chemicals and chemical classes that can be measured in human tissue and excreta, effects of a child's age on the type and amount of biological samples available for analysis). These research complexities are discussed in the context of developing more effective and efficient exposure assessment methods.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"611-29"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500142","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21959873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pesticide exposure and creatinine variation among young children.","authors":"M K O'Rourke,&nbsp;P S Lizardi,&nbsp;S P Rogan,&nbsp;N C Freeman,&nbsp;A Aguirre,&nbsp;C G Saint","doi":"10.1038/sj.jea.7500119","DOIUrl":"https://doi.org/10.1038/sj.jea.7500119","url":null,"abstract":"<p><p>Pesticide exposure may differentially impact young children; they live closer to the ground and take in greater amounts of food relative to body mass than older children or adults. We are using an organophosphate (OP) urinary biomarker screen (gas chromatography with flame photometric detection, GC/FPD) to evaluate pesticide exposure among 154 children < or = 6 years of age living in a heavily farmed border (US-Mexico) community. The screen detects diethylphosphates (DEPs) and dimethylphosphates (DMPs) above a reference range of 1000 non-occupationally exposed individuals (DL=25 microg/g creatinine, Cr). At least one metabolite was detected for 33% of the subjects; many samples contained multiple biomarkers. DEP was detected in 5% of the subjects. DMP and DMTP were frequently measured (25% and 26%, respectively). Biomarker concentrations are adjusted by the body's metabolism of Cr as an indicator of urine dilution. Cr concentrations were examined separately to evaluate their effect on internal dose measures. Cr concentrations were significantly different by season (K-W=0.83, P=0.022). Significant differences exist between the autumn:spring (P=0.038) Cr concentrations and between summer:autumn (P=0.041) Cr concentrations based on Mann-Whitney U=1070.5, z=-2.041, (P=0.041). Our analysis of NHANES III data did not reflect seasonal Cr differences for 6 year olds. No younger children were included. Absorbed daily dose (ADD) estimates were calculated for children with the highest concentrations of metabolite. Calculations are theoretical values assuming that the entirety of a given metabolite was metabolized from a single pesticide. Several class appropriate pesticides were evaluated. For the children with the highest levels, almost all estimated ADDs exceeded the RfD. Although the actual metabolite concentrations dropped appreciably, ADD were still exceeded RfDs at the 95th percentile. The urinary OP screen was effective in identifying subjects with atypical internal doses. Daily Cr yield is a critical component in ADD calculations. Cr variability produces differences in internal dose measurement and estimates of ADD independent of exposure. Cr variability among young children needs to be examined, and caution should be applied when evaluating Cr adjusted internal doses for children.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"672-81"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500119","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21960421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental contaminants in human milk.","authors":"H A Anderson,&nbsp;M S Wolff","doi":"10.1038/sj.jea.7500133","DOIUrl":"https://doi.org/10.1038/sj.jea.7500133","url":null,"abstract":"<p><p>Environmental contaminants can be stored in the mother's body or can be transiently present from current diet, occupational exposures or personal habits. These chemicals can be transferred prenatally to the developing fetus or postnatally from breast milk to the nursing infant. Exposures through breast milk can be substantial, especially when the mother has significant ongoing exposures or has accumulated an unusually high body burden of persistent chemicals. Several studies demonstrate that organochlorines (OCs) acquired from breast milk elevate a child's body burden for several years. The decline of persistent OC residues in Western countries suggests that these exposures through breast milk will also diminish. Heavy metals such as lead and mercury are also present in milk, but the pharmacokinetics are quite different from OCs. Less persistent environmental agents, including solvents, polycyclic aromatic hydrocarbons, certain pesticides, and nicotine, can also be detected in milk. There is little information on currently used pesticides and other more recently identified environmental agents for which exposures are common today. Epidemiologic research has established that pre- and postnatal exposures to environmental contaminants including lead and OCs are associated with developmental deficits in early childhood. Therefore, characterization of these contaminants in breast milk can add to our knowledge of potential environmental exposures among children.</p>","PeriodicalId":15789,"journal":{"name":"Journal of Exposure Analysis and Environmental Epidemiology","volume":"10 6 Pt 2","pages":"755-60"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1038/sj.jea.7500133","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"21960427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}