Population toxicokinetics of tetrachloroethylene

 In assessing the distribution and metabolism of toxic compounds in the body, measurements are not always feasible for ethical or technical reasons. Computer modeling offers a reasonable alternative, but the variability and complexity of biological systems pose unique challenges in model building and adjustment. Recent tools from population pharmacokinetics, Bayesian statistical inference, and physiological modeling can be brought together to solve these problems. As an example, we modeled the distribution and metabolism of tetrachloroethylene (PERC) in humans. We derive statistical distributions for the parameters of a physiological model of PERC, on the basis of data from Monster et al. (1979). The model adequately fits both prior physiological information and experimental data. An estimate of the relationship between PERC exposure and fraction metabolized is obtained. Our median population estimate for the fraction of inhaled tetrachloroethylene that is metabolized, at exposure levels exceeding current occupational standards, is 1.5% [95% confidence interval (0.52%, 4.1%)]. At levels approaching ambient inhalation exposure (0.001 ppm), the median estimate of the fraction metabolized is much higher, at 36% [95% confidence interval (15%, 58%)]. This disproportionality should be taken into account when deriving safe exposure limits for tetrachloroethylene and deserves to be verified by further experiments. Received: 20 April 1995/Accepted: 24 August 1995     

An Historical Perspective from the Green Revolution to the Gene Revolution

Since the 1960s conventional crop breeding has increased food production commesurate with the growing population. For agricultural development to continue, the exploitation of greater genetic diversity and modern biotechnology are becoming increasingly important. This article reviews the milestones achieved by the Green Revolution and many of the recent breakthroughs of modern biotechnology.     

血管紧张素转换酶基因与中国人群冠心病、高血压病及糖尿病的关系

目的：研究血管紧张素转换酶(ACE)基因与中国人群冠心病(CHD)、高血压病(EH)及2型糖尿病(T2DM)的关系。方法：250例呈不同组合的EH、T2DM以及CHD患者及90例正常对照用改良的聚合酶链反应(PCR)方法检测ACE基因型，比较基因型及等位基因频率分布。结果：①无合并CHD的T2DM及EH组ACE基因型及等位基因频率与正常对照无显著差异；②CHD组无论是否合并EH及／或T2DM，Ⅲ基因型及Ⅰ等位基因频率均显著低于正常对照，而DD基因型及D等位基因频率均显著高于正常对照；③T2DM合并CHD组及EH合并CHD组中Ⅱ基因型及Ⅰ等位基因频率均显著低于正常对照，而DD基因型及D等位基因频率均显著高于正常对照。结论：ACE基因多态性与中国人群CHD相关。这种关联亦见于EH或T2DM合并CHD中，但ACE基因仅是CHD发病的遗传学基础，而与是否合并EH及／或T2DM无关。     

Plasma amine oxidase activities in Norrie disease patients with an X-chromosomal deletion affecting monoamine oxidase

Summary Two individuals with an X-chromosomal deletion were recently found to lack the genes encoding monoamine oxidase type A (MAO-A) and MAO-B. This abnormality was associated with almost total (90%) reductions in the oxidatively deaminated urinary metabolites of the MAO-A substrate, norepinephrine, and with marked (100-fold) increases in an MAO-B substrate, phenylethylamine, confirming systemic functional consequences of the genetic enzyme deficiency. However, urinary concentrations of the deaminated metabolites of dopamine and serotonin (5-HT) were essentially normal. To investigate other deaminating systems besides MAO-A and MAO-B that might produce these metabolites of dopamine and 5-HT, we examined plasma amine oxidase (AO) activity in these two patients and two additional patients with the same X-chromosomal deletion. Normal plasma AO activity was found in all four Norrie disease-deletion patients, in four patients with classic Norrie disease without a chromosomal deletion, and in family members of patients from both groups. Marked plasma amine metabolite abnormalities and essentially absent platelet MAO-B activity were found in all four Norrie disease-deletion patients, but in none of the other subjects in the two comparison groups. These results indicate that plasma AO is encoded by gene(s) independent of those for MAO-A and MAO-B, and raise the possibility that plasma AO, and perhaps the closely related tissue AO, benzylamine oxidase, as well as other atypical AOs or MAOs encoded independently from MAO-A and MAO-B may contribute to the oxidative deamination of dopamine and 5-HT in humans.     

Application of fluorescence in situ hybridization techniques in clinical genetics: use of two alphoid repeat probes detecting the centromeres of chromosomes 13 and 21 or chromosomes 14 and 22, respectively

Two cloned DNA fragments, one derived from an alpha satellite subfamily common to chromosomes 13 and 21, and the other derived from a similar subfamily common to chromosomes 14 and 22, have been used as biotinylated probes in in situ hybridization studies. Under high stringency conditions, chromosome specific centromeric labelling can be obtained. The applications of this technique in clinical situations are illustrated on metaphases from a fetus with trisomy 21, a fetus with trisomy 13, and a child with clinical features of cat-eye syndrome.     

Evolution and path models in human behavioral genetics

The evolutionary implications of the path-analysis model most often used in human behavior genetics are examined. With directional selection, a model of pure vertical environmental transmission does not respond in a fully adaptive fashion. Unless the coefficients of transmission are exactly 0.50, the population mean will not equilibrate at the selective optimum over time. If there is both genetic and vertical environmental transmission, then the population mean can equilibrate at the selective optimum. In the presence of genetic transmission, vertical environmental transmission increases population fitness and has a strong effect on the rapid movement of the mean toward the selective optimum. This raises the intriguing paradox of why empirical evidence suggests that vertical environmental transmission is usually small when it possesses such important fitness properties.This work was supported in part by Grant DA05131 from the National Institute on Drug Abuse.     

Creating a place for population health: Interpreting the spaces of a new School in Auckland,New Zealand

Although the reconfiguring of health care within the hospital sector has gained considerable attention by social scientists, the tertiary education sector's response to new health philosophies and practices has proceeded largely unexamined. This paper considers the new School of Population Health at the University of Auckland, accounts for its origins and considers the synergies between its design and workplace organisation. The results of a thematic analysis of narratives offered by 24 employees collected in 2004 are then presented. Findings suggest that the amassing of academics from a range of health-related backgrounds is advancing interdisciplinary dialogue even if the nature and purpose of population health remains unclear to some. A key concern of respondents was the openness of the workplace which encourages a collaborative atmosphere but also generates distraction. The degree to which conduct within the new building is perceived as regulated was also of concern. Place clearly matters in the story of the new School: the form of the building (featuring an architecture of openness) complements its function (generating new collaborations and creative thinking about health). However, the question of how ‘salutogenic’ a setting it is remains contested.     

中国蒙,汉族酒依赖与醇脱氢酶和醛脱氢酶基因多态性的相关研究

为探讨醇脱氢酶（ＡＤＨ）基因和醛脱氢酶（ＡＬＤＨ）基因多态性与酒依赖患病的相互关系，用耳血干血痕聚合酶链反应、等位基因特异性寡核苷酸探针方法，检测乙醇代谢酶ＡＤＨ和ＡＬＤＨ基因型在我国蒙、汉民族酒依赖与非酒依赖者中分布频率。结果显示在酒依赖组（汉族５２例，蒙族３１例）与正常对照组（汉族４８例，蒙族３５例）之间：汉族的ＡＬＤＨ２基因型频率与等位基因频率的分布差异有非常显著性（Ｐ＜０．０１），而蒙族则表示为ＡＤＨ２基因型频率与等位基因频率的分布差异有非常显著性（Ｐ＜０．０１）。这提示汉族酒依赖的发病与ＡＬＤＨ２基因有关，蒙族则与ＡＤＨ２基因有关。