Occurrence of aflatoxins, fumonisin B1, and zearalenone in foods and feeds in Botswana

Sorghum and maize form the main dietary staple foods in Botswana. Other products such as peanuts, peanut butter, phane (an edible larval stage of an emperor moth Imbrasia belina Westwood), and pulses (cowpeas and beans) are also widely used as food and for the manufacture of feeds. These important food and feed commodities were analyzed for the presence of aflatoxins, fumonisin B1, and zearalenone. Aflatoxins were detected in 40% of the samples analyzed. The concentration of total aflatoxins ranged from 0.1 to 64 microg/kg. The mean concentration ranged from 0.3 microg/kg in sorghum to 23 microg/kg in peanut butter. Peanut butter samples were the most contaminated (71%). No aflatoxins were detected in maize. Fumonisin B1 was detected in 36% of the samples. Maize samples were the most contaminated (85% of the samples) with the concentration ranging from 20 to 1,270 microg/kg. No fumonisin B1 was detected in peanuts, phane, and beans. Zearalenone was only found in 2.6% of the samples analyzed at 40 microg/kg. Aflatoxins were the most common toxins detected in foods and feeds in Botswana. However, fumonisin B1 was more prevalent in maize than aflatoxins or zearalenone.     

Lyme disease, Rocky Mountain spotted fever, ehrlichiosis: emerging and established challenges for the clinician

OBJECTIVE: The goal of this review is to facilitate the management of patients with tick-associated diseases. This article will discuss the epidemiology, clinical diagnosis, and antimicrobial therapy of Lyme disease, Rocky Mountain spotted fever, and ehrlichiosis. DATA SOURCES: References are limited to the English language and extend back to the beginning of the twentieth century. The human and veterinary literature were reviewed. Sources include computerized databases and bibliographies of recent articles and books. STUDY SELECTION: Papers were selected on the basis of their timeliness, explanation of important findings by major investigators, extrapolation of clinical data from large patient populations, and clarification of controversial issues. Approximately 50% of the articles initially reviewed are included in the bibliography. RESULTS: Standardization of laboratory testing for Lyme disease should facilitate more accurate diagnosis in the future. Clinical diagnosis of Rocky Mountain spotted fever and ehrlichiosis prior to laboratory confirmation is necessary in order to ensure timely institution of antimicrobial therapy. CONCLUSIONS: Knowledge of endemic regions and seasonal cycles of vectors, varying clinical presentations of disease and appropriate utilization of the laboratory are critical for the appropriate diagnosis and management of patients with tick-associated diseases.     

Z/I and A-band lattice spacings in frog skeletal muscle: effects of contraction and osmolarity

A-band and Z-line/I-band lattice spacings were measured by small-angle X-ray diffraction from relaxed and isometrically-contracting whole frog sartorius muscles with lattice spacings reduced or swollen by changing the osmolarity of the bathing solution. A-band spacing increased by approximately 3% upon isometric contraction at reduced lattice spacings (245-356 mOsm) and decreased by approximately 1% at swollen spacings (172 mOsm), similarly to the behaviour of skinned muscles upon changing from the relaxed state to rigor. The Z/I lattice underwent a significant lattice expansion (3-8%) upon isometric contraction at all osmolarities, in qualitative agreement (but quantitative disagreement) with results from electron microscopy on mammalian skeletal muscle. Lattice areas calculated for the Z/I and A-band lattices indicate a barrel-shaped sarcomere in the resting state, which may provide a partial explanation for how longitudinal forces produced in the A-band can produce a radial expansive force in the Z-line during contraction. The radial component of cross-bridge stiffness was calculated from the A-band data for contracting muscle, using a lattice stability model incorporating structural, osmotic and electrostatic forces. The calculations gave a radial cross-bridge stiffness during contraction of about 9 x 10(5) N m-2, and outward radial force per thick filament in normal Ringer's solution of 6 x 10(-9) N, corresponding to a radial force per cross-bridge of 10(-11) N.     

Utility of ischemic scores in the differential diagnosis of Alzheimer's disease and ischemic vascular dementia

Despite new developments in the concept of vascular dementia, the Hachinski Ischemic Score (HIS) and its modified versions continue to be widely used in the clinical differentiation of Alzheimer's disease (AD) and ischemic vascular dementia (IVD). The sensitivity of the HIS and two modified versions in the diagnosis of AD, IVD, and single infarcts in a large, geriatric population with mild cognitive impairment (N = 100) was evaluated. Sensitivity for identification of AD was greater than 90% but was less than 70% for IVD. Over one third of patients with one or more infarcts on computed tomographic brain scans and 63% of mixed cases were classified as having probable AD. It is concluded that ischemic scores may be useful at predicting prevalence rates if individual case accuracy is ignored. Despite being sensitive to identifying AD, ischemic scores are insensitive to both cerebral infarction and IVD and cannot reliably exclude IVD. Finally, patients with mixed dementia should not be expected to have intermediate scores.     

RANTES-induced T cell activation correlates with CD3 expression

The chemokine RANTES induces a unique biphasic cytoplasmic Ca2+ signal in T cells. The first phase of this signal, similar to that of other chemokines, is G-protein mediated and chemotaxis associated. The second phase of this signal, unique to RANTES and evident at concentrations greater than 100 nM, is tyrosine kinase linked and results in a spectrum of responses similar to those seen with antigenic stimulation of T cells. We show here that certain jurkat T cells responded to RANTES solely through this latter pathway. A direct correlation between the RANTES-induced second phase response and CD3 expression was demonstrated in these cells. Sorting the Jurkat cells into CD3(high) and CD3(low) populations revealed that only the CD3(high) cells were responsive to RANTES. Furthermore, stimulation of these Jurkat cells with anti-CD3 mAb significantly depresses their subsequent response to RANTES. While a RANTES-specific chemokine receptor is expressed at a low level on these Jurkat cells, the RANTES-induced activation is dependent on the presence of the TCR. Thus, stimulation through TCR may partially account for RANTES' unique pattern of signaling in T cells.     

Ethical evaluation of hypnosis research: a survey of investigators and their institutional review boards

We surveyed hypnosis researchers and Institutional Review Boards (IRBs) with regard to the ethical evaluation of research protocols. Researchers and IRB administrators were independently surveyed within the same institutions. Both objective and free response items were used to address substantive issues such as deception and at-risk populations, as well as practical matters such as paperwork. Parallel questions allowed a point-counterpoint between researchers and IRBs. Overall, the results suggest that IRBs do not treat hypnosis research differently than other types of research. We end with recommendations for facilitating interactions between hypnosis researchers and their IRBs.     

Constrained length minimum inductance gradient coil design

A gradient coil design algorithm capable of controlling the position of the homogeneous region of interest (ROI) with respect to the current-carrying wires is required for many advanced imaging and spectroscopy applications. A modified minimum inductance target field method that allows the placement of a set of constraints on the final current density is presented. This constrained current minimum inductance method is derived in the context of previous target field methods. Complete details are shown and all equations required for implementation of the algorithm are given. The method has been implemented on computer and applied to the design of both a 1:1 aspect ratio (length:diameter) central ROI and a 2:1 aspect ratio edge ROI gradient coil. The 1:1 design demonstrates that a general analytic method can be used to easily obtain very short gradient coil designs for use with specialized magnet systems. The edge gradient design demonstrates that designs that allow imaging of the neck region with a head sized gradient coil can be obtained, as well as other applications requiring edge-of-cylinder regions of uniformity.     

海洋潮差区混凝土表面微生物16S rDNA分子鉴定

针对目前海洋混凝土工程的腐蚀现状,进行了海洋微生物对潮差区混凝土的作用机理及完善海工混凝土的腐蚀机理探索.通过海工混凝土潮差区部位取样,对暴露于潮差区中部22 y的混凝土试样表面进行FE-SEM、EDAX分析,结果表明:潮差区混凝土表面腐蚀严重,结构疏松,表面覆盖有有机物质和微生物.并将暴露于潮差区中部22 y的混凝土试样和该取样位置挂置7 d的混凝土试样表面的微生物群落分别分离,克隆了其中30株和12株细菌的16S rDNA基因,测定其序列且进行比对,其分别属于15个和7个种属中.优势种属均为假交替单胞菌,但随着暴露时间的增加,总细菌株数和总菌属数分别增大到2.5和2.14倍,且种属的变化也很大.同时,建立了海洋混凝土工程表面细菌鉴定方法,以及分离、鉴定的菌种为后续细菌对混凝土作用的试验提供菌种.     

钢纤维混凝土高温后SHPB试验研究

为了研究钢纤维混凝土(SFRC)常温以及经历400和800℃高温后的动态压缩性能,采用改进的分离式Hopkinson压杆装置,结合应变直测技术对其进行了单轴冲击压缩试验.结果表明:经历400和800℃高温后,未掺钢纤维混凝土的峰值应力分别只有常温时的79.2%和38.9%,弹性模量分别降为常温时的82.8%和56.2%,同时,试件的能量吸收能力大幅度下降;钢纤维混凝土400,800℃对应的峰值应力分别降为常温时的76.8%和39.0%,弹性模量稍有降低,分别为常温的91.8%和82.7%,较基准混凝土有了较大的提高.钢纤维的加入可以增加混凝土的极限应力对应应变,曲线的下降段较为平缓,同时增强了混凝土的能量吸收能力,在20,400和800℃时,分别提高了38.5%,27.5%和25%.