Using 16O35Cl to correct for chloride interference improves accuracy of urine arsenic determinations by inductively coupled plasma mass spectrometry.

We have observed inaccurate urine arsenic values with the method of isobaric fractionation, which was designed to correct for the 40Ar35Cl interference with 75As quantitation by inductively coupled plasma mass spectrometry. Isobaric fractionation, which is based on ion intensities at m/z 77 and 82, consistently underestimates the 40Ar35Cl interference and overestimates urine arsenic. We present an improved method for identifying the argon-chloride interference. We observed that signal intensities for the species 16O35Cl and 40Ar35Cl are proportional (I75 = 0.0295 x I51 - 14.7, r2 = 0.998; where Ix is the normalized ion intensity at m/z X) in water and urine, over a broad range of chloride concentrations (0-800 mmol/L). The proportionality constant is remarkably stable within a run (mean and SD, 0.0295 +/- 0.0023, based on 10 replicates of five chloride calibrators, 0, 100, 200, 400, and 800 mmol/L). Increased sensitivity (50-fold) for detecting the 40Ar35Cl interference provides improved accuracy for urine arsenic quantitation as demonstrated by a split-sample comparison with graphite-furnace atomic absorption spectrophotometry.     

大狼毒三萜类化学成分的研究

自大戟科(Euphorbiaceae)植物大狼毒(Euphorbia nematocypha Hand—Mazz)根的乙醇提取物的苯溶解部分,经20%AgNO₃硅胶层析,分离得到七个三萜类成分。根据光谱(IR,EIMS,¹H—NMR和¹³C—NMR)和化学方法,确定其中一个化合物为新化合物,命名为大狼毒醇(nematocyphol,Ⅳa),其它化合物为已知物:印度荆芥醇乙酸酯(nepehinol acetate Ⅰ),日尔曼醇乙酸酯(germanicol acetate Ⅱ),大戟醇(euphol,Ⅲ),蒲公英醇(taraxasterol,Ⅴa),24-亚甲基环阿尔廷醇(24-methylenecycloartanol,Ⅴa)和印度荆芥醇(nepehinol,Ⅶa)。这些化合物均为首次从大狼毒中得到。     

Preventing child abuse: An experimental evaluation of the child parent enrichment project

Perinatal child abuse prevention projects are increasingly favored but rarely evaluated. The paper describes an experimental evaluation of the Child Parent Enrichment Project (CPEP). Women were referred to the project during or just after pregnancy if identified as at-risk of engaging in child abuse by community professionals. Clients were randomly assigned to CPEP services (n=24) or traditional community services (n=26). CPEP services involved six months of home visiting by paraprofessional women and linkage to other formal and informal community resources. Multivariate Analysis of Covariance on posttest scores, controlling for pretest scores, show advantage for the CPEP group in prenatal care, birth outcomes, better reports of child temperament, and better indicators of child welfare. CPEP mothers tended to report better well-being. No significant differences were demonstrated for levels of formal and informal support. Reports of child abuse were similar for both groups. Consumer satisfaction indicates that clients valued the program. The preliminary results argue for further use and evaluation of perinatal child abuse prevention services.The authors thank Sharon Ikami and CPEP staff and volunteers. Richard P. Barth, D.S.W. is Associated Professor at the School of Social Welfare, University of California, Berkeley. Susan Hacking, Ph.D. was Project Director and Jordana Ash, M.S.W. is Child Welfare Worker, Alameda County Department of Social Services. Funding was provided by Bio-Medical Research Support Grant 2-507-RR07006 Resources from the Division of Research National Institute of Health, the State of California Office of Child Abuse Prevention, and the Office of Human Development Services ACYF, DHHS (Grant #90-CA-0998).     

Selection of a lysine-resistant CHO-K1 mutant with reduced amino acid transport through multiple systems

High levels ofl-lysine were used to select for resistant variants of Chinese hamster ovary (CHO-K1) cells. Surviving colonies were screened for altered lysine transport and two with reduced uptake were picked. Clone CH-K^r, derived from the more severely affected colony, was analyzed in detail. In starved cells theV _max of lysine uptake in CH-K^r was half that of CHO whileK _m was unaltered. The intracellular pool of lysine, a substrate of cationic amino acid transport system y⁺, was significantly lower in CH-K^r. However, transport and pools of other amino acids, which are not substrates of y⁺, were also reduced in CH-K^r, as was the internal sodium concentration, while hexose import was increased. It appears that the mutation in CH-K^r is pleiotropic, affecting some general aspects of amino acid transport.