Comparative Study of Blood Lead Levels in Uruguayan Children (1994–2004)

Lead does not fulfill any physiological function in the human body. It is generally accepted that the blood lead level (BLL) is the best exposure index, as there is an excellent correlation between the actual exposure of the individual and the concentration of lead in blood. In Uruguay, lead contamination becomes a matter of public concern in 2001, giving rise to a sensitization in the population, which in many cases brought about a change in hygienic and dietary habits of the children. In 2004, after the leaded gasoline phasing out process in Uruguay was completed, we studied non-exposed children to correlate BLL with variables such as age, sex, area of residence, and available environmental lead data and compared these results with those from our similar screening studies 10years ago. The main result of this comparison is that BLL from children in our country had a significant decrease between 1994 and 2004.     

Binary regression in truncated samples, with application to comparing dietary instruments in a large prospective study

Summary .   We examine two issues of importance in nutritional epidemiology: the relationship between dietary fat intake and breast cancer, and the comparison of different dietary assessment instruments, in our case the food frequency questionnaire (FFQ) and the multiple-day food record (FR). The data we use come from women participants in the control group of the Dietary Modification component of the Women's Health Initiative (WHI) Clinical Trial. The difficulty with the analysis of this important data set is that it comes from a truncated sample, namely those women for whom fat intake as measured by the FFQ amounted to 32% or more of total calories. We describe methods that allow estimation of logistic regression parameters in such samples, and also allow comparison of different dietary instruments. Because likelihood approaches that specify the full multivariate distribution can be difficult to implement, we develop approximate methods for both our main problems that are simple to compute and have high efficiency. Application of these approximate methods to the WHI study reveals statistically significant fat and breast cancer relationships when a FR is the instrument used, and demonstrate a marginally significant advantage of the FR over the FFQ in the local power to detect such relationships.     

Trapped in keratin; a comparison of dermatophyte detection in nail, skin and hair samples directly from clinical samples using culture and real-time PCR

Traditionally, laboratory detection and identification of dermatophytes consists of culture and microscopy which yields results within approximately 2-6 weeks. In 2007 our medical microbiological diagnostic laboratory implemented a molecular method for the detection of dermatophytes. A real-time PCR assay was developed which simultaneously detects and identifies the most prevalent dermatophytes directly in nail, skin and hair samples and has a turnaround time of less than two days. For 1437 clinical samples, received by our diagnostic laboratory, we compared the results obtained from both culture and real-time PCR. This study showed that real-time PCR significantly increased the detection rate of dermatophytes compared to culture. Furthermore, excellent concordance between culture and real-time PCR identification was achieved.     

Exact Confidence Bounds for Comparing Two Regression Lines with a Control Regression Line on a Fixed Interval

The problem of finding exact simultaneous confidence bounds for comparing simple linear regression lines for two treatments with a simple linear regression line for the control over a fixed interval is considered. The assumption that errors are iid normal random is considered. It is assumed that the design matrices for the two treatments are equal and the design matrix for the control has the same number of copies of each distinct row of the design matrix for the treatments. The method is based on a pivotal quantity that can be expressed as a function of four t variables. The probability point depends on the size of an angle associated with the interval. We present probability points for various sample sizes and angles. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

脉冲-扩散周期竞争系统解的渐近行为

研究了在周期变化环境中具有扩散及种群密度可能发生突变的两竞争种群动力系统的数学模型．模型由反应扩散方程组以及初边值及脉冲条件组成．文章建立了研究模型的上下解方法,获得了一些比较原理．利用脉冲常微分方程的比较定理以及利用相应的脉冲常微分方程的解控制和估计所讨论模型的解,研究了系统模型的解的渐近性质．     

Synthesis of amino acyl adenylates using thetert-butoxycarbonyl protecting group

Summary Alanyl, [¹⁴C]-alanyl, phenylalanyl, and methionyl adenylates have been synthesized in high yields and relatively good purities. Elemental analysis¹H nmr and ir spectra have been utilized for the characterization of these extremely labile compounds. The present synthesis, which uses readily available N-tert-butoxycarbonyl amino acids, is compared with previous methods.     

Traveling Waves and Spread Rates for a West Nile Virus Model

A reaction–diffusion model for the spatial spread of West Nile virus is developed and analysed. Infection dynamics are based on a modified version of a model for cross infection between birds and mosquitoes (Wonham et al., 2004, An epidemiological model for West-Nile virus: Invasion analysis and control application. Proc. R. Soc. Lond. B 271), and diffusion terms describe movement of birds and mosquitoes. Working with a simplified version of the model, the cooperative nature of cross-infection dynamics is utilized to prove the existence of traveling waves and to calculate the spatial spread rate of infection. Comparison theorem results are used to show that the spread rate of the simplified model may provide an upper bound for the spread rate of a more realistic and complex version of the model.     

Soluble microbial products (SMP) and soluble extracellular polymeric substances (EPS) from wastewater sludge

Laspidou and Rittmann (Water Research 36:2711–2720, 2002) proposed that the soluble extracellular polymeric substances (EPS) are identical to soluble microbial products (SMP) in sludge liquor. In this paper, we compared the physicochemical characteristics of the SMP and soluble EPS from original and aerobically or anaerobically digested wastewater sludge. The surface charges, particle sizes, residual turbidities of polyaluminum chloride (PACl) coagulated supernatant, and chemical compositions of the SMP and soluble EPS containing suspensions were used as comparison index. Experimental results revealed that the particles in SMP and soluble EPS fractions extracted from original wastewater sludge, before and after digestion, were not identical in all physicochemical characteristics herein measured. The current test cannot support the proposal by Laspidou and Rittmann (Water Research 36:2711–2720, 2002) that SMP is identical to the soluble EPS from a wastewater sludge.     

云南小麦、西藏半野生小麦和普通小麦叶绿体DNA限制性内切酶图谱的研究

云南小麦(Triticum aestivum ssp.yunnanense King)和西藏半野生小麦(Triticum aestivum ssp.tibetanum Shao) 是我国西部地区特有的两个普通小麦(T.aestivum L.)亚种。我们采用改进的高离子强度法,提取云南小麦、西藏半野生小麦、普通小麦的两个品种(中国春和鄂恩1号)的叶绿体DNA, 并用7种限制性内切酶对它们的叶绿体DNA进行了酶切图谱分析。结果表明:在普通小麦及其两个亚种中没有叶绿体DNA的限制性片段长度差异,反映了叶绿体基因组在进化过程中相对的稳定性。 Abstract:Yunnan wheat(Triticum aestivum ssp. Yunnanense King) and Tibet semiwild wheat (Triticum aestivum ssp. Tibetanum Shao) are two endemic subspecies of common wheat (T. eastivum L.) in the west of China.Improved high ionic strength medium was adopted to extract the cpDNAs of Yunnan wheat,Tibet semiwild wheat and two cultivars of common wheat (Chinese Spring and Een 1).Restriction fragment analysis of cpDNAs was carried out with the use of 7 restriction enzymes.The results showed that there was no diversity of cpDNAs from common wheat and the two subspecies,indicating the conservatism of the chloroplast genome during the process of evolution.     

不同产地中华马氏钳蝎神经毒素的分离纯化和部分性质比较研究

经Ｓｅｐｈａｄｅｘ Ｇ－５０,Ｓｐ－Ｓｅｐｈａｄｅｘ Ｃ－２５两次柱层析,从没产地的东亚马氏钳歇粗毒中分别得到了一组碱性哺乳动物神经素和一种甲壳类神经毒素,对它们进行的等电点、分子量、动物毒性等部分性质的研究与比较结果表明,淅川、常德与益都产的蝎毒无论在柱层析行为上,还是在等电点、分子量、各组分的毒性大顺序及某些对应组分的结晶行为上有很大相似性,仅存在略微的差异。