青叶胆及其混淆品的生药鉴别

本文报道了青叶胆(Swertia mileensis)及其混淆品紫花獐牙菜(S.punicea)、显脉獐牙菜(S.nervasa)和椭圆叶花锚(Halenia elliptica)的性状、显微及理化特性的比较研究。结果表明其有明显的差异,易于鉴别。为该药材的准确鉴定和质量评价提供依据。     

软骨性肿瘤的电脑图象分析及其分类识别

应用电脑图象分析法,对各不同恶性度的软骨性肿瘤的组织切片图象进行了处理及测量。发现大视场内的细胞数量,以及单个细胞核的切面周长、面积和圆度等均随各类肿瘤恶性度的增加循序,而出现循序递增或循序递减的光谱带样演变过程。运用线性分类法及自组织分类法,对各类肿瘤的各特征参数进行自动分类识别,亦取得较好结果。表明电脑图象分析结果在软骨性肿瘤良恶性鉴别及分类识别中,可作为一客观的指标。     

Electron microscopic evidence of persistent chlamydial infection following treatment

Chlamydia trachomatis infections of the female and male genital tracts are often asymptomatic and, thus, tend to become persistent. In the persistent state the typical Chlamydia life cycle is arrested and standard antibiotic regimens do not always eradicate this infection. We sought to relate treatment failures in men and women with persistent chlamydial genital tract infections to electron microscopic evidence of chlamydial persistence and with atypical morphological forms of the organism. Of 16 patients with chlamydial persistence following azithromycin treatment, morphological variants of this organism were observed by electron microscopy from one endocervical sample and one male urethral sample. We document the presence of intracellular inclusions containing only reticulate bodies, extracellular monomembrane and polymembrane phagosomes containing elementary bodies and reticulate bodies with abnormal outer membranes in the process of dividing extracellularly. These observations parallel previous in vitro studies of chlamydial persistence under adverse conditions. This capacity of C. trachomatis to undergo atypical morphological alterations in vivo may contribute to its persistence and relative resistance to antibiotics.     

System identification theory in pharmacokinetic modeling of dynamic contrast-enhanced MRI: influence of contrast injection.

Optimization of experimental settings of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), like the contrast administration protocol, is of great importance for reliable quantification of the microcirculatory properties, such as the volume transfer-constant K(trans). Using system identification theory and computer simulations, the confounding effects of volume, rate and multiplicity of a contrast injection on the reliability of K(trans) estimation was assessed. A new tracer-distribution model (TDM), based on in vivo data from rectal cancer patients, served to describe the relationship between the contrast agent injection and the blood time-course. A pharmacokinetic model (PKM) was used to describe the relation between the blood and tumor tissue time-courses. By means of TDM and PKM in series, the tissue-transfer function of the PKM was analyzed. As both the TDM and PKM represented low-frequency-pass filters, the energy-density at low frequencies of the blood and tissue time-courses was larger than at high frequencies. The simulations, based on measurements in humans, predict that the K(trans) is most reliable with a high injection volume administered in a single injection, where high rates only modestly improve K(trans).     

General method for rapid synthesis of multicomponent peptide mixtures

A method is suggested for the synthesis of multicomponent peptide mixtures. The method is a solid phase synthesis modified in order to give a closely equimolar mixture of peptides with predetermined sequences. The main point of modification is that before every coupling cycle the resin is divided into equal parts and each portion is coupled with a different amino acid. Then the portions are mixed and before the next coupling cycle the resin is again distributed into equal portions. The method is illustrated by the synthesis of a mixture of 27 tetrapeptides and that of 180 pentapeptides.     

Differentiation of three species of ixodid tick, Dermacentor andersoni, D. variabilis and D. albipictus, by PCR-based approaches using markers in ribosomal DNA

Three species of Dermacentor, Dermacentor albipictus, Dermacentor andersoni and Dermacentor variabilis, commonly occur in Canada. D. andersoni and D. variabilis are morphologically similar and are important vectors of human and animal pathogens. A practical polymerase chain reaction (PCR) assay, based on the amplification of part of the second internal transcribed spacer ribosomal DNA (pITS-2 rDNA), was developed to distinguish D. andersoni from D. variabilis. In addition, single-strand conformation polymorphism (SSCP) analysis of the pITS-2 rDNA provided a reliable method of distinguishing specimens of the three species of ixodid tick. PCR and pITS-2 SSCP were also used to determine whether there was hybridization between D. andersoni and D. variabilis at two localities in Saskatchewan where they occur in sympatry. These molecular tools will be useful for the unequivocal identification of D. andersoni and D. variabilis at all life cycle stages, which is essential for studies on their ecology and on the transmission of tick-borne diseases. Also, pITS-2 SSCP may be of potential use for discriminating among the other morphologically similar species within the genus Dermacentor.     

Mesh Size Control of Organic‐Inorganic Hybrid Gels by Means of a Hydrosilylation Co‐Gelation of Siloxane or Silsesquioxane and α, ω‐Non‐Conjugated Dienes

Organic‐inorganic hybrid gels have been synthesized by means of co‐gelation of multi‐functional cyclic siloxane, 1,3,5,7‐tetramethylcyclotetrasiloxane (TMCTS), or cubic silsesquioxane, 1,3,5,7,9,11,13,15‐octakis(dimethylsilyloxy)pentacyclo‐[9,5,1,1,1,1]octasilsesquioxane (POSS), as crosslinking reagents with α,ω‐non‐conjugated dienes, a hexa‐1,5‐diene (HD) and deca‐1,9‐diene (DD) mixture, using hydrosilylation reaction with Pt catalyst. Network structures of the resulting co‐gels have been quantitatively characterized by means of a novel scanning microscopic light scattering system. The feed ratio of HD to DD strongly affects the gelation and mesh size of the co‐gels. The critical concentration of gelation has maximum values in the co‐gelation with a feed ratio of [HD]/[DD] = 1. The mesh‐size of the resulting co‐gels underwent changes with the [HD]/[DD] ratio in the feed, and the structure (geometry) of the crosslinking reagents affect the trend of the mesh size change. The TMCTS‐HD/DD co‐gel obtained with a feed ratio of [HD]/[DD] = 1, showed the minimum mesh size. Whereas the mesh size of the POSS‐HD/DD co‐gel increased with an increase of DD in the feed ratio. The mesh‐size distribution of the co‐gels was narrower than the gels synthesized from single α,ω‐non‐conjugated dienes. Co‐gelation of a TMCT/POSS‐DD system was also investigated, and the critical gelation concentration showed maximum values for the co‐gelation with a feed ratio of [TMCTS]/[POSS] = 1. The mesh size of the co‐gel increased with increasing POSS ratio in the feed.

     

Determination of gender by measuring the size of the maxillary sinuses in computerized tomography scans

Background Identification of corpses is a difficult forensic procedure and it is mandated by laws and social rules. Comparison of ante mortem and post-mortem medical records, such as dental documents, plays an important role in the identification of corpses. However, typical identification methods may be inconclusive, especially when certain extreme post-mortem changes have developed. Gender has long been determined from the skull, the pelvis and the long bones with an epiphysis and a metaphysis in unknown skeletons. The aim of this study was to investigate whether the width, the length and the height of the maxillary sinuses could be used for determination of gender. Materials and Methods The width, the length and the height of the maxillary sinuses were measured in 127 adult patients who were admitted to the Department of Radiology for computed tomography scans of their sinuses. Of 127 patients, 62 (48.8%) were females and 65 (51.2%) were males. The width, the length and the height of the maxillary sinuses were measured in Computerized Tomography scans (Hitachi Radix Turbo computed tomography) when the patients were in prone position without sedation or contrast medium. The data were subjected to a discriminative analysis using the SPSS package program (Version 11.5). Results The discriminative analysis showed that the accuracy of maxillary sinus measurements—i.e. the ability of the maxillary sinus size to identify gender—was 69.4% in females and 69.2% in males. Conclusion Computerized Tomography measurements of maxillary sinuses may be useful to support gender determination in forensic medicine; however, with a relatively low-accuracy rate (less than 70%).     

Host-feeding patterns of Culex mosquitoes in relation to trap habitat

Mosquito feeding patterns identify vertebrate species potentially involved in the amplification of West Nile virus. In New York, northern cardinals (Cardinalis cardinalis) were the predominant hosts in most habitats. Crow (Corvus sp.) blood meals were most frequently identified from sewage treatment plant and storm water catch basin habitats.