Evolving trends in steroid hormone receptor research

Recent advances have challenged classical notions regarding the nature of steroid hormone receptors in the cell including localization, activation, configuration, and stability. Molecular biology has revealed a remarkable similarity in the primary structure of a wide variety of receptor classes that goes beyond steroid action. Post-translational modification of a primary unit, expressed in response to genetic conservatism, would appear to assure receptor dynamics specific to hormone-, organ-, and tissue-dependent processes, and may even lead to toxicity and oncogenicity.     

Blood transferrin receptor expression in chromosomally abnormal fetuses

In a cross-sectional study of 13 chromosomally abnormal fetuses, umbilical venous blood was obtained by cordocentesis at 17–32 weeks' gestation. Fetal blood transferrin receptor (CD71) expression (mean=79·8 per cent, range=60–98 per cent) and nucleated red cell count (mean=10·4 × 10⁹ per 1, range=1·0–25·0 × 10⁹ per 1) were significantly higher than the appropriate normal mean for gestation (z=3·92, P<0·0001 and z=3·69, P<0·001, respectively). These haematological changes in chromosomally abnormal fetuses would facilitate their prenatal diagnosis by analysis of fetal nucleated red blood cells isolated from the maternal circulation on the basis of CD71 expression.     

大气颗粒物源解析受体模型优化技术研究

针对大气颗粒物来源解析技术存在的2大问题:二次有机碳(SOC)对CMB模型的影响及源与受体不匹配程度对源成分谱共线性的影响,给出了解决方案.对于SOC影响的问题,提出从受体的角度扣除SOC,对CMB模型进行修正,降低SOC的影响;对于共线性问题,提出了PCA/MLR-CMB复合模型,复合模型首先进行PCA/MLR的解析,降低受体中未知源的影响,使得纳入CMB模型中的源和受体匹配程度大大提高,从而使得共线性源类能够得到理想的结果.     

PCDFs的Ah受体结合能力的定量结构效应关系

应用单苯环氯取代方法取G₁～G₁₀10个分子结构描述符,通过正向逐步线性回归方法构建对于Ah受体结合能力的定量结构-性质相关(QSAR)模型.与有关文献相比,此模型能更好地预测多氯代二苯并呋喃(PCDFs)竞争结合Ah受体logEC₅₀值,各自变量间不存在共线性.模型可以较好地反映PCDFs分子Ah受体结合能力与其分子氯取代位点之间的关系.     

Dealing with near collinearity in chemical mass balance receptor models

The amount of airborne particulate pollution attributable to various sources can be estimated from a linear least squares (LLS) fit of concentrations of chemical elements observed at a receptor to the known elemental composition of the particles emitted by the sources. The resulting least squares problem often displays a high degree of ill-conditioning and associated inflation of the uncertainties in the estimates. Because of the physical constraints of the problem, variable selection and ridge regression cannot be used to remedy the ill-conditioning. In particular, it is shown that a stable ridge regression solution is equivalent to assuming sources of airborne particulates with negative elemental composition. A method is developed which defines, for a specific level of acceptable uncertainty, three classes of sources; those which can be estimated accurately by LLS, those which cannot be so estimated and those which cannot be accurately estimated individually but participate in linear combinations which can be accurately estimated. A technique is presented which determines those linear combinations of source contributions of minimum variance.     

An insulin receptor in microorganisms: Fact or fiction ?

We are greatly indebted to the Fonds der Chemischen Industrie for financial support.     

有机锡通过核受体干扰内分泌的研究进展

有机锡能够作为视黄酸x受体（Retinoid X receptor,RXR）和与过氧化物酶体增殖物激活受体γ（Peroxisome proliferator—activated receptor γ,PPARγ）的激动剂,对RXR激活可能和引起螺类性畸变有关。有机锡还可能通过激活RXR／PPARγ异源二聚体促进脊椎动物脂肪分化和影响脂质代谢平衡。     

Prenatal analysis of insulin receptor autophosphorylation in a family with leprechaunism

We describe a method for the isolation and functional characterization of insulin receptors from chorionic villi and cultured amniotic fluid cells. The functionality of these receptors is assayed by measuring the insulin-induced stimulation of autophosphorylation of the receptor β-chain. The method is expected to allow the prenatal diagnosis of those forms of lep-rechaunism and related diseases which are the result of a decreased stimulation by insulin of receptor autophosphorylation. A pregnancy at risk for leprechaunism was examined and an unaffected child was correctly predicted by study of the functionality of the insulin receptor on cultured amniocytes and by echoscopic examination.