Reproductive isolation revealed in preliminary crossbreeding experiments using field collected Triatoma dimidiata (Hemiptera: Reduviidae) from three ITS-2 defined groups

Triatoma dimidiata, a Chagas disease vector distributed in Mexico, Central America, Colombia, Venezuela, Peru and Ecuador, has been studied using genetic markers and four groups have been defined by ITS-2 sequences: 1A, 1B, 2 and 3. To gather evidence on the divergence and reproductive isolation among T. dimidiata ITS-2 groups, we carried out 15 crossbreeding experiments with field-collected sylvan and domestic T. dimidiata from Guatemala where three groups are found: 1A, 2 and 3. Reciprocal crosses between individuals from groups 1A and 2, and a cross between group 2 individuals from different habitats, produced an average 129.78 ± 42.29 eggs with hatching success ranging from 31.6 to 90.1%. The offspring of these crosses reached the adult stage, and crosses between F1 insects produced eggs. These results suggest that there are no pre- or post-zygotic reproductive barriers between groups 1A and 2, or within group 2. Crosses between group 3 females and males from groups 1A or 2 produced on average 85.67 ± 30.26 eggs and none of them hatched. These results support the existence of pre-zygotic barriers between T. dimidiata group 3 and groups 1A and 2. The group 3 individuals were collected in sylvatic environments in Yaxha, Peten, Guatemala. Previously, distinct chromosomal characteristics (cytotype 3) were described in individuals from this population. Based on this evidence we suggest that this population is divergent at the species level from other T. dimidiata populations.     

Activationless charge transport across 4.5 to 22 nm in molecular electronic junctions

In this work, we bridge the gap between short-range tunneling in molecular junctions and activated hopping in bulk organic films, and greatly extend the distance range of charge transport in molecular electronic devices. Three distinct transport mechanisms were observed for 4.5–22-nm-thick oligo(thiophene) layers between carbon contacts, with tunneling operative when d < 8 nm, activated hopping when d > 16 nm for high temperatures and low bias, and a third mechanism consistent with field-induced ionization of highest occupied molecular orbitals or interface states to generate charge carriers when d = 8–22 nm. Transport in the 8–22-nm range is weakly temperature dependent, with a field-dependent activation barrier that becomes negligible at moderate bias. We thus report here a unique, activationless transport mechanism, operative over 8–22-nm distances without involving hopping, which severely limits carrier mobility and device lifetime in organic semiconductors. Charge transport in molecular electronic junctions can thus be effective for transport distances significantly greater than the 1–5 nm associated with quantum-mechanical tunneling.     

Transverse relaxation of cells labeled with magnetic nanoparticles.

We describe the NMR relaxation properties of magnetically labeled cells. The cells are labeled with magnetic nanoparticles (SPIO, USPIO), which generate susceptibility contrast. The geometry of the labeled cells and the surrounding tissue is considered. We assume that the magnetic nanoparticles accumulate to form a magnetic core of radius RC inside the cell. The correlation time tau, which describes the motion of spins around this core, is analyzed. Using the strong collision approach, explicit expressions are derived for the transverse relaxation rate R2* for tissue containing labeled cells as a function of the core radius, the diffusion coefficient, and the concentration of the nanoparticles. The predictions of this model agree well with numerical simulations and experimental data.     

跳受控制的局部平方可积鞅的渐近行为

对局部平方可积鞅,若其可料二次变差趋于无穷,在其跳满足不同的增长条件时,本文给出了鞅本身不同的增长速度。     

平板运动试验的强阳性与冠状动脉多支病变的相关性——附74例临床资料分析

平板运动试验(TET)在冠心病的定量诊断方面,我国尚应用不够,作者选择7项表现,作为强阳性依据,对74例因胸痛拟诊冠心病入院者,于冠状动脉造影(CAG)前作了TET检查.其中男性58例,女性16例,年龄为57.5±8.4岁(38～74岁).结果显示,以强阳性估测多支病变(包括左主干病变)的敏感性为59%,特异性高达100%.作者认为敏感性略低可能与冠心病严重的评判标准不同有关,亦与本文患者大多(70%)服用抗心绞痛药物有关,而特异性高则说明冠状动脉正常或病变轻者极少表现为强阳性.冠心病严重度的初步无创性评估对CAG的操作及患者的疗效分析均有实际意义.     

Hospitalizations for opioid poisoning: a nation-wide population-based study in Denmark, 1998–2004

Aims   To assess hospitalization rates (HR) for poisoning with heroin, methadone or strong analgesics and relate them to quantities of prescribed methadone and strong analgesics in Denmark between 1998 and 2004.
Design   Population-based ecological study.
Settings   We extracted data on all emergency department visits and hospital admissions registered in the Danish National Patient Registry with a diagnosis of poisoning with heroin ( n  = 1688), methadone ( n  = 173) or strong analgesics ( n  = 384). To ascertain sale of prescribed medications we used data from the Danish Medicines Agency.
Measurements   Age- and gender-standardized HR and defined daily doses (DDD) per 1000 people per day.
Findings   HR for heroin poisoning was 4.4 [95% confidence interval (CI): 3.8–4.9] per 100 000 person-years (p-y) in 1998 and 4.6 (CI: 4.0–5.2) per 100 000 p-y in 2004. HR for methadone poisoning increased from 0.1 (CI: 0.0–0.2) per 100 000 p-y in 1998 to 1.1 (CI: 0.8–1.4) per 100 000 p-y in 2004. HR for poisoning with strong analgesics increased from 0.6 (CI: 0.4–0.9) per 100 000 p-y in 1998 to 2.1 (CI: 1.8–2.6) per 100 000 p-y in 2004. The sale of prescribed strong analgesics (5.0 DDD per 1000 people per day in 1998 to 5.9 DDD in 2004) and methadone (3.0 DDD per 1000 people per day in 1998 to 3.4 DDD in 2004) increased slightly between 1998 and 2004.
Conclusion   Increasing sale of prescribed methadone and strong analgesics coincided with increasing HRs of poisoning with these drugs, whereas HR of heroin poisoning varied. Further longitudinal studies are important for the guidance of future policy making.     

The anion gap (AG): studies in the nephrotic syndrome and diabetic ketoacidosis (DKA)

Although "unmeasured" anions contribute to metabolic acidosis in a variety of disease states, they are generally not measured directly but estimated from the calculation of "gaps." Among the most commonly used method, the anion gap (AG) is not only a function of "unmeasured" anions, but also it is a function of plasma non-carbonate buffers (albumin and phosphate), the plasma pH, and the method of measurement. To clarify the contribution of non-carbonate buffers to the AG, the Figge-Fencl-Waston model of human plasma was applied to laboratory values obtained from two novel populations, patients with nephrotic syndrome and patients with diabetic ketoacidosis (DKA). The model performed adequately, justifying the common clinical practice of correcting the AG for the net protein charge.     

Silymarin protects PBMC against B(a)P induced toxicity by replenishing redox status and modulating glutathione metabolizing enzymes—An in vitro study

PAHs are a ubiquitous class of environmental contaminants that have a large number of hazardous consequences on human health. An important prototype of PAHs, B(a)P, is notable for being the first chemical carcinogen to be discovered and the one classified by EPA as a probable human carcinogen. It undergoes metabolic activation to QD, which generate ROS by redox cycling system in the body and oxidatively damage the macromolecules. Hence, a variety of antioxidants have been tested as possible protectors against B(a)P toxicity. Silymarin is one such compound, which has high human acceptance, used clinically and consumed as dietary supplement around the world for its strong anti-oxidant efficacy. Silymarin was employed as an alternative approach for treating B(a)P induced damage and oxidative stress in PBMC, with an emphasis to provide the molecular basis for the effect of silymarin against B(a)P induced toxicity. PBMC cells exposed to either benzopyrene (1 μM) or silymarin (2.4 mg/ml) or both was monitored for toxicity by assessing LPO, PO, redox status (GSH/GSSG ratio), glutathione metabolizing enzymes GR and GPx and antioxidant enzymes CAT and SOD. This study also investigated the protective effect of silymarin against B(a)P induced biochemical alteration at the molecular level by FT-IR spectroscopy. Our findings were quite striking that silymarin possesses substantial protective effect against B(a)P induced oxidative stress and biochemical changes by restoring redox status, modulating glutathione metabolizing enzymes, hindering the formation of protein oxidation products, inhibiting LPO and further reducing ROS mediated damages by changing the level of antioxidant enzymes. The results suggest that silymarin exhibits multiple protections and it should be considered as a potential protective agent for environmental contaminant induced immunotoxicity.