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.     

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.     

Abundance of saccharides and scarcity of glycosaminoglycans in the soft tissue of clam, Meretrix meretrix (Linnaeus)

We investigated presence and distribution of glycosaminoglycans (GAGs) in Meretrix meretrix soft tissue by determining GAG composition in the different parts, namely, mantle edge, foot, gill, adductor muscle, and viscera. The occurrence of glycan ingredients was examined by histochemistry, whereas GAG and general polysaccharide contents in clam tissue were qualified through extraction and determination. Tissue sections stained with alcian blue or periodic acid–Schiff demonstrated the general existence of saccharides and trifling generation of GAGs in clam tissues. GAGs coexisting with glycogens appeared to be primarily produced in the mantle and foot tissues in mucus form by visualization. The GAG content of the polysaccharide extract ranged from 16.8 to 75.8?mg in 10?g of 5 dried tissue materials in comparison with total carbohydrate level in the range of 500–1760?mg, thereby indicating that GAGs were not the major components of polysaccharide extracts. GAG composition only accounted for approximately 4% of total glycan components, which consist of the determinations of amino sugar and uronic acid. The soft tissues of clam contained abundant saccharide compounds but sparse amounts of GAGs. The results will benefit the subsequent development of products made from the polysaccharide components of M. meretrix.     

Short‐term cytokine stimulation reveals regulatory T cells with down‐regulated Foxp3 expression in human peripheral blood

The identification of regulatory T cells (Treg cells) in human peripheral blood is an important tool in diagnosis, research, and therapeutic intervention. As compared to lymphoid tissues, the frequencies of circulating Treg cells identified as CD4⁺CD25⁺Foxp3⁺ are, however, low. We here show that many of these cells remain undetected due to transient down regulation of Foxp3, which rapidly decays in the absence of cytokine‐mediated STAT5 signals. Short‐term incubation of PBMCs or isolated CD4⁺ T cells, but not of lymph node cells, with IL‐2, ‐7, or ‐15 more than doubles the frequency of Foxp3⁺CD25⁺ among CD4⁺ T cells detectable by flow cytometry. This increase is not due to cell division but to upregulation of both proteins. At the same time, the uncovered Treg cells up‐regulate CD25 and down‐regulate CD127, making them accessible to viable cell sorting. “Latent” Treg cells have a demethylated FOXP3 TSDR sequence, are enriched in naïve, non‐cycling cells, and are functional. The confirmation of our findings in RA and SLE patients shows the feasibility of uncovering latent Treg cells for immune monitoring in clinical settings. Finally, our results suggest that unmasking of latent Treg cells contributes to the increase in circulating CD4⁺CD25⁺Foxp3⁺ cells reported in IL‐2 treated patients.     

自贡市非结核分枝杆菌临床分离株的菌种鉴定结果分析

目的 对自贡市35株疑似非结核分枝杆菌（NTM）临床分离株进行菌种鉴定。方法 从自贡市各区（县）及市结核病防治获得的临床分枝杆菌分离株,通过罗氏培养基（L-J）、对硝基苯甲酸（PNB）和噻吩-2-羧酸肼（TCH）鉴别培养基初步鉴定为NTM,再经多位点PCR方法确定为NTM后,对rpoB、hsp64及its基因进行测序及分析鉴定。结果 35株疑似NTM临床分离株,通过初步鉴别,多位点PCR,rpoB、hsp64及its基因测序及分析鉴别出32株NTM,分别为脓肿分枝杆菌（M. abscessus）11株、胞内分枝杆菌（M. intracellulare）7株、堪萨斯分枝杆菌（M. kansasii）5株、鸟分枝杆菌（M. avium）3株、脓毒分枝杆菌（M. septicum）1株、马赛分枝杆菌（M. masseillense）1株、戈登分枝杆菌（M. gordonae）2株、副瘰疬分枝杆菌（M. parascrofulaceum）1株和Mycobacterium peregrinum 1株。结论 抗酸染色阳性、PNB/TCH鉴定为NTM的临床分离株中包含不同种类的NTM,自贡市NTM肺病的病原种类较多,以快生长脓肿分枝杆菌为主,其次为慢生长不产色菌的胞内分枝杆菌和缓慢生长光产色菌的堪萨斯分枝杆菌。实验室应开展进一步菌种鉴定,以指导临床正确诊断和合理治疗。     

改良早期预警评分识别病情临床应用现状

文章介绍了改良早期预警评分系统的概念及评分方法,归纳了国内外有关改良早期预警评分在门急诊分诊处置、预测识别住院危重症患者、院内患者转运及陪检、预测患者预后和在护理管理中应用的相关研究,并在此基础上,对改良早期预警评分的研究前景进行了展望。