Children's diets,pesticide uptake,and implications for risk assessment: An Israeli case study

The presence of pesticides in the Israeli food supply is well documented but little is known about the risks posed by children's diets for potential exposures. We investigated potential exposures to food-borne pesticides in a sample of 301 urban Israeli children (2008–10). Data from a food frequency questionnaire, 24 hour food recall, and Israel's national pesticide monitoring program were used to estimate uptake factors for 26 compounds in 27 fruits and vegetables. A pilot risk assessment was performed and the findings were compared with the Israel Ministry of Health's 2012 pesticide risk assessment for the general population. The surveyed children had higher potential exposures than the general population for over one third of the compounds, and uptake factors exceeded the Acceptable Daily Intake in ten compounds. Methamidophos, exceeded the ADI at the 25th percentile and fenamiphos, iprodione, and oxydemethon methyl, exceeded the ADI at the 50 percentile. ADIs for several compounds were exceeded even though the residues detected were below the statutory limit. Improved monitoring, enforcement, and revision of the Maximum Residue Limit for certain food/pesticide pairs are indicated as is the need to incorporate data on children's actual food consumption in national risk assessments.     

Pesticide assessment: Protecting public health on the home turf

Pesticide regulation is examined in the context of Health Canada’s Pest Management Regulatory Agency’s assessment of the chlorophenoxy herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) for turf. 2,4-D is the most common herbicide used to kill weeds in grass.The medical literature does not uniformly indicate harms from herbicides. However, the balance of epidemiological research suggests that 2,4-D can be persuasively linked to cancers, neurological impairment and reproductive problems. These may arise from 2,4-D itself, from breakdown products or dioxin contamination, or from a combination of chemicals.Regulators rely largely on toxicology, but experiments may not replicate exposures from 2,4-D application to lawns because environmental breakdown products (eg, 2,4-dichlorophenol) may not accumulate and selected herbicides are possibly less contaminated. Dioxins are bioaccumulative chemicals that may cause cancer, harm neurological development, impair reproduction, disrupt the endocrine system and alter immune function. No dioxin analyses were submitted to the Pest Management Regulatory Agency, and the principal contaminants of 2,4-D are not among the 17 congeners covered in pesticide regulation. Independent assessment of all dioxins is needed, in tissues and in the environment.The 2,4-D assessment does not approach standards for ethics, rigour or transparency in medical research. Canada needs a stronger regulator for pesticides. Potentially toxic chemicals should not be registered when more benign solutions exist, risks are not clearly quantifiable or potential risks outweigh benefits. Until landscaping pesticides are curtailed nationally, local bylaws and Quebec’s Pesticide Code are prudent measures to protect public health. Physicians have a role in public education regarding pesticides.     

德国小蠊抗药性及其抗性衰退情况研究

目的了解德国小蠊的抗药性及抗药性衰退情况.方法以点滴法测定德国小蠊对溴氰菊酯、敌敌畏、二氯苯醚菊酯、残杀威等的抗药性及抗药性衰退情况.结果现场品系分别为0.098、0.490、5.612、0.741ug/虫,正常饲养1年后抗性分别为0.086、0.232、3.412、0.317ug/虫,5年后抗性分别为0.008、0.123、0.410、0.0811ug/虫,LD50最高为二氯苯醚菊酯,1年后抗性衰退倍数范围为1.14～2.39,5年后抗性衰退倍数范围为3.98～13.69.结论具有高等抗性德国小蠊经实验室饲养5年后抗性基本衰退.     

一种识别蛋白质的保守氨基酸残基的新方法

保守氨基酸残基在生物进化过程中具有较强的稳定性,一般不会发生太大的变化;生物信息学认为：氨基酸序列决定蛋白质结构,蛋白质结构决定蛋白质功能。因此,作者基于氨基酸的生化特性、几何特性和动态特性描述了一个新颖的算法去发现蛋白酶家族中的保守氨基酸残基,而保守氨基酸残基将对蛋白质的结构和功能的研究具有重要的意义。     

马杜霉素渣抗球虫的效果

测定了马杜霉素渣中铅、砷、镉、铬的含量及对小白鼠的毒性和对鸡的抗球虫性能。试验结果：马杜霉素渣中铅含量１．０５ｍｇ／ｋｇ，砷含量小于１．０ｍｇ／ｋｇ，镉含量１．２ｍｇ／ｋｇ，铬含量２６ｍｇ／ｋｇ；马杜霉素渣对小白鼠的ＬＤ５０为３５４．６５ｍｇ／ｋｇ，比马杜霉素毒性大。马杜霉素渣的抗球虫指数为１７３～１７５．１，属中等强度抗球虫药。以上结果表明，马杜霉素渣可以作为抗球虫药应用，但应用时要防止中毒的发生。     

敌枯双慢性毒性实验的病理形态学研究——实验大鼠脏器组织病理变化

将150只SD大鼠随机地分成Ⅰ,Ⅱ,Ⅲ,Ⅳ四个实验组和一个对照组(Ⅴ)。实验组敌枯双剂量分别为1.0,0.2,0.05及0.01mg/kg,均用去离子水配成相应浓度的染毒水,由动物自由摄取,对照组摄入去离子水。于实验第29.5,55周分两批处死。经组织病理学检查,结果发现:敌枯双可引起甲状腺滤泡上皮细胞萎缩甚至脱屑,其发生率(Ⅲ组为63.64%)与对照组(0%)比较差异有高度显著性(P<0.01);睾丸曲细精管各级生精细胞减少、萎缩甚至完全消失,其发生率(Ⅳ组为58.33%)与对照组(8.33%)比较差异有显著性(P<0.01);对心肌、肝组织也有不同程度的损伤.     

Structure-activity studies of hydrophobic amino acid replacements at positions 9, 11 and 16 of glucagon

We have designed and synthesized eight compounds 2-9 which incorporate neutral, hydrophobic amino acid residues in positions 9, 11 and 16 of the glucagon molecule: (2) [desHis¹,Va1⁹,11e^11,16] glucagon amide, (3) [desHis¹,Val^9,11,16]glucagon amide, (4) [desHis¹,Va1⁹,Leu^11,16]glucagon amide, (5) [desHis¹,Nle⁹,11e^11,16]glucagon amide, (6) [desHis¹,Nle⁹,Val^11,16]glucagon amide, (7) [desHis¹,Nle⁹,Leu^11,16]glucagon amide, (8) [desHis¹,Val⁹,Leu^11,16,Lys^17,18,Glu²¹]glucagon amide and (9) [desHis¹,Nle⁹,Leu^11,16,Lys^17,18,Glu²¹]glucagon amide. The effect of neutral, hydrophobic residues at positions 9, 11 and 16 led to good binding to the glucagon receptor. Compared to glucagon (IC₅₀= 1.5 nM), analogues 2-9 were found to have IC₅₀ values of 6.0, 6.0, 11.0, 9.0, 2.5, 2.8, 6.5 and 7.0 nM, respectively. When these compounds were tested for their ability to block adenylate cyclase (AC) activity, they were found to be antagonists having no stimulation of adenyl cyclase, with PA₂, values of 6.15, 6.20, 6.30, 7.25, 6.10, 7.30, 6.25 and 7.25, respectively. © Munksgaard 1997.     

Hen liver and plasma can metabolize hexyl-DCP phosphoramidate at a rate comparable to that of rat

The in vitro and in vivo biochemical properties of O-hexyl, O-dichlorophenyl phosphoramidate (hexyl-DCP) as inhibitor of acetylcholinesterase (AChE) and neuropathy target esterase (NTE) were studied, as well as their neurotoxic effects. The differences found were suggested to be due to biotransformation effects. In this work, the in vitro time-dependent degradation of hexyl-DCP by plasma, liver and brain homogenates of rat and hen at 37°C at pH 7.4 are studied using 100 nM initial concentration. The loss of inhibitory potency against AChE was used as sensor of the biodegradation rate. An approximate estimation of the residual compound was made by comparison with an inhibition calibration curve. The rate of enzymatic degradation was corrected for the spontaneous hydrolysis. Rat tissues showed some higher activities (24, 17, 1 mU/g for plasma, liver, and brain, respectively) than hen (17, 6, 1 mU/g), with activities being highest for plasma and lowest for brain. Hexyl-DCP is a chiral compound. The loss of anti-AChE power could be due to degradation of only one of the two stereoisomers.     

Isolation and characterization of entomopox virions from virus-containing inclusions of Amsacta moorei (Lepidoptera: Arctiidae)

Preparations of Amsacta moorei entomopox virions were obtained from virus-containing inclusions (VCI) by using a carbonate-thioglycolate solution (pH 10.7–11.5). The virions possessed a uniform coat (“halo”) surrounding the viral envelope and exhibited an RNA polymerase activity. The “halo” could be removed by prolonged exposure to the carbonate-thioglycolate solution. Virions obtained by this treatment, however, possessed low infectivity and no detectable RNA polymerase activity. Removal of the “halo” by trypsin resulted in virions which possessed RNA polymerase activity and relatively high infectivity.Preparations of particles with and without the “halo” were similar in percent DNA, protein per OD₂₆₀, number of particles per OD₂₆₀, and RNA polymerase activity. Particles without the “halo,” however, were less dense (1.262 g/cm³) in CsCl than those with the “halo” (1.282 g/cm³) and 15–45 times more infective.Parallel studies of “nonhaloed” Amsacta virions (trypsin-treated) and vaccinia virions showed that both viruses contained similar amounts of protein per OD₂₆₀, but Amsacta virions contained only 36% of the DNA found in vaccinia.     

Characterization of a 105-kDa plasma membrane associated glycoprotein that is involved in West Nile virus binding and infection

This study attempts to isolate and characterize West Nile virus-binding molecules on the plasma membrane of Vero and murine neuroblastoma cells that is responsible for virus entry. Pretreatment of Vero cells with proteases, glycosidases (endoglycosidase H, alpha-mannosidase), and sodium periodate strongly inhibited West Nile virus infection, whereas treatments with phospholipases and heparinases had no effect. The virus overlay protein blot detected a 105-kDa molecule on the plasma membrane extract of Vero and murine neuroblastoma cells that bind to WN virus. Treatment of the 105-kDa molecules with beta-mercaptoethanol resulted in the virus binding to a series of lower molecular weight bands ranging from 30 to 40 kDa. The disruption of disulfide-linked subunits did not affect virus binding. N-linked sugars with mannose residues on the 105-kDa membrane proteins were found to be important in virus binding. Specific antibodies against the 105-kDa glycoprotein were highly effective in blocking virus entry. These results strongly supported the possibility that the 105-kDa protease-sensitive glycoprotein with complex N-linked sugars could be the putative receptor for WN virus.