The essential role of stimulus temporal patterning in enabling perceptual learning

Little is known about how temporal stimulus factors influence perceptual learning. Here we demonstrate an essential role of stimulus temporal patterning in enabling perceptual learning by showing that 'unlearnable' contrast and motion-direction discrimination (resulting from random interleaving of stimuli) can be readily learned when stimuli are practiced in a fixed temporal pattern. This temporal patterning does not facilitate learning by reducing stimulus uncertainty; further, learning enabled by temporal patterning can later generalize to randomly presented stimuli.     

Use of Monoclonal Antibodies That Recognize p60 for Identification of Listeria monocytogenes

Listeria monocytogenes causes major food-borne outbreaks of disease worldwide. Specific identification of this microorganism is of utmost importance to public health and industry. Listeria species are known to secrete a 60-kDa protein collectively termed p60, which is encoded by the iap (invasion-associated protein) gene and secreted in large quantities into the growth media. p60 is a highly immunogenic murein hydrolase that is essential for cell division. Due to these properties, p60 is an ideal diagnostic target for the development of immunological detection systems for L. monocytogenes. We report here two independent lines of monoclonal antibody (MAb): p6007, which specifically recognizes L. monocytogenes p60, and p6017, which reacts with a wide range of Listeria p60 proteins. By combining these antibodies with a polyclonal antibody, we developed efficient sandwich enzyme-linked immunosorbent assay (ELISA) systems which can specifically identify L. monocytogenes or generally detect Listeria species. Since an excess amount of the peptide corresponding to PepA or PepD did not interfere with the ELISA, and direct ELISAs were unable to detect both peptides, we concluded that the epitope presumed to be recognized by p6007 or p6017 could be distinguished from PepA and PepD as described by Bubert et al. (Appl. Environ. Microbiol. 60:3120-3127, 1997). To our best knowledge, this is the first example of an immunological identification system that uses p60-recognizing MAbs.     

浅谈医学生的医学文化素质教育

随着时代的进步,教育思想发生着深刻的变革。加强医学生的素质教育,努力提高医学生的综合素质,为社会培养高素质的应用型医学人才,成为医学教育界的共识。医学文化素质是医学生的综合素质之一,由医学科学素质与医学人文素质综合构成[1],努力提高医学生的医学文化素质在医学教育中尤显必然。1医学科学素质随着科学技术的飞速发展,医学已发展为多学科、多专业互相综合与交叉的学科,这就要求医学生不仅要具备扎实的医学理论,而且应具备精湛的临床技能。只有牢固掌握了全面扎实的专业理论知识和娴熟的专业操作技能,才能沉着冷静地面对复杂多变的…     

大鼠眼上直肌神经的生后发育

取生后两天、两周和两月的雄性Ｗｉｓｔａｒ大鼠双眼上直肌，进行硝酸银染色和乙酰胆碱酯酶染色，用光镜观察大鼠眼上直肌神经在生后的发育情况。在大鼠生后两天时，动眼神经的分支从眼上直肌的中后三分之一交界处由眶面进入该肌，它向该肌的球面区发出细小的神经纤维束，这些神经束抵达同一条肌纤维上。眶面层神经纤维细小，单条并且平行于肌纤维方向走行。此时，眼上直肌对乙酰胆碱酯酶染色着色浅，反应区未形成某一特定轮廓，说明此时运动神经的发育是不成熟的。在生后两周时，动眼神经的分支开始向眼上直肌的眶面层发出神经纤维；球面区中的神经纤维有明显的粗细两种。这时眼上直肌中的运动神经轴索对乙酰胆碱酯酶染色反应，出现葡萄状运动神经末梢及斑点状运动终板的雏形。生后两月时，眼上直肌中出现了肌梭及典型的葡萄状运动神经末梢和斑点状运动终板。生后两周是大鼠睁眼初期，由此可见，大鼠从闭眼至睁眼的时期，是运动神经发育的关键时期，此时，运动神经形成一些特定神经末梢，而睁眼后运动神经的发育主要在此基础上运动神经末梢日趋完善和成熟。     

IL—6基因转染的瘤苗体内诱导的抗肿瘤免疫功能与效果

经丝裂霉素C体外处理后,将IL-6基因转染的、高分泌的IL-6的B16黑色素瘤细胞制成瘤苗。结果发现,体内注射IL-6基因转染的瘤苗后,小鼠脾脏CTL活性、NK活性及IL-2诱导的LAK活性显著升高。经IL-6基因转染瘤苗体内治疗后,荷瘤小鼠的皮下肿瘤生长显著减慢、肺转移结节数显著降低、存活期显著延长,若同时合用低剂量IL-2,则上述治疗效果更好。可见IL-6基因转染的瘤苗能有效地通过诱导机体抗肿瘤免疫功能而发挥抗肿瘤作用,与低剂量IL-2合用后,IL-6基因转染的瘤苗的抗肿瘤效果更佳。     

Chromophobe renal cell carcinoma

Chromophobe renal cell carcinoma (RCC) is a recently established subtype of RCC, which has rarely been reported in Japan. In this communication, the authors report two Japanese cases of chromophobe RCC together with the immunohistochemical findings. The tumors were composed of sheets and cribriform glands formed by tumor cells with cloudy and reticular cytoplasm. Ultrastructurally, the cytoplasm was filled with numerous microvesicles. The tumor cells were positive for cytokeratin, epithelial membrane antigen, and Tamm-Horsfall protein. Occasionally, LeuM1-positive cells were also noted. Vimentin was negative, unlike the usual RCC. Reactivity for peanut agglutinin was more frequent than that to Lotus tetragonolobus agglutinin. The results of this study suggest that the tumor cellq possessed phenotypes similar to the distal nephron rather than to the proximal tubular cells.     

狗股动脉拉伸损伤后的顺应性变化

采用成年狗正常股动脉段６例，测定其拉伸后的压力一容积关系，并求出其顺应性。另取狗股狗股动脉段３０例拉伸固定后，观测其形态结构变化。发现狗股动脉段拉伸后的Ｐ－Ｖ曲线可用抛物线来拟合，狗股动脉段拉伸１５％后顺应性明显下降，其形态结构无明显改变，拉伸３０％后才出现明显的结构改变。狗股动脉拉伸后顺应性变化的出现较形态结构变化早。     

选择性肠道清洁法对重症烫伤大鼠肠源性内毒素血症的影响

本实验采用大鼠４０％Ⅲ°烫伤模型，初步观察了选择性肠道清洁法（ＳＤＤ）对肠源性内毒素血症的防治效果。结果发现，防治组动物门、体循环内毒素水平伤后均显著降低（Ｐ＜０．０５～０．０１），各段肠腔内游离内毒素含量较烫伤对照组下降９９．５％以上。且肠道细菌易位率致伤１～５天都明显减少，回肠粘膜二胺氧化酶活性逐渐恢复。防治组大鼠严重烫伤５天存活率提高２６．７％（Ｐ＜０．０５）。本结果提示，该方法对于重症烫伤大鼠肠源性内毒素血症具有显著防护效应，并能抑制肠道细菌的移居与减轻肠粘膜的进一步损害。因此，及早进行ＳＤＤ可能有助于烧伤后肠源性感染及其它并发症的防治。     

Survey of the Distribution of a Newly Characterized Receptor for Advanced Glycation End Products in Tissues

Advanced glycation end products (AGEs), the final products of nonenzymatic glycation and oxidation of proteins, are found in the plasma and accumulate in the tissues during aging and at an accelerated rate in diabetes. A novel integral membrane protein, termed receptor for AGE (RAGE), forms a central part of the cell surface binding site for AGEs. Using monospecific, polyclonal antibody raised to human recombinant and bovine RAGE, immunostaining of bovine tissues showed RAGE in the vasculature, endothelium, and smooth muscle cells and in mononuclear cells in the tissues. Consistent with these data, RAGE antigen and mRNA were identified in cultured bovine endothelium, vascular smooth muscle, and monocyte-derived macrophages. RAGE antigen was also visualized in bovine cardiac myocytes as well as in cultures of neonatal rat cardiac myocytes and in neural tissue where motor neurons, peripheral nerves, and a population of cortical neurons were positive. In situ hybridization confirmed the presence of RAGE mRNA in the tissues, and studies with rat PC12 pheochromocytes indicated that they provide a neuronal-related cell culture model for examining RAGE expression. Pathological studies of human atherosclerotic plaques showed infiltration of RAGE-expressing cells in the expanded intima. These results indicate that RAGE is present in multiple tissues and suggest the potential relevance of AGE-RAGE interactions for modulating properties of the vasculature as well as neural and cardiac function, prominent areas of involvement in diabetes and in the normal aging process.     

Studies on silicone-grafted copolyimides, 3. Synthesis of soluble polyimide/polydimethylsiloxane graft copolymer and application to separation membrane

Polyimide/polydimethylsiloxane (PI/PDMS) graft copolymer was prepared following the macromonomer method. First, 3-(3,5-diaminobenzyloxy)propyl-terminated polydimethylsiloxane (DAB-PDMS) was prepared by hydrosilylation of allyl 3,5-dinitrobenzyl ether with hydrosilyl-terminated PDMS, followed by catalytic reduction of the two nitro groups. PI/PDMS graft copolymer was synthesized by polycondensation of DAB-PDMS with 4,4′-oxydianiline (ODA) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), followed by chemical imidation. The average degree of polymerization of the PDMS chain was in the range between 7 and 25. The resulting graft copolymers were soluble in several organic solvents. Membranes were prepared by solvent casting, followed by heating at 220°C in vacuo, upon which the membranes became hardly soluble in organic solvents. The gas permeability coefficients of the graft copolymer membranes were much greater than those of the polyimide homopolymer and of the same order as that of a PDMS membrane. Furthermore, a selective permeation of organic liquids, e.g., tetrahydrofuran, acetone and acetonitrile, was observed in the pervaporation of aqueous organic liquids through the copolymer membrane.