Identification of M cells and their distribution in rabbit intestinal Peyer's patches and appendix

The distribution of intestinal membranous (M) cells has been studied within the follicle-associated epithelium of rabbit Peyer's patches and appendix. Vimentin expression has been assessed as a primary criterion to identify rabbit M cells in tissue sections and in whole tissue preparations. This criterion has been compared to the use of the absence of alkaline phosphatase which, due to its heterogeneous distribution within the enterocyte population, is less reliable than vimentin expression as a marker for rabbit M cells. The pattern of vimentin immunostaining revealed that the majority of M cells are located in the periphery of the follicle-associated epithelium, the dome apex being largely free of M cells. This distribution was confirmed by scanning electron microscopy. Vimentin is also expressed by follicle-associated epithelial cells in the vicinity of crypts which lack the typical lymphocyte-containing pocket of M cells. Cytoplasmic peanut agglutinin binding coincides with vimentin-expression throughout the follicle-associated epithelium but is absent from vimentin-negative enterocytes. The co-localisation of these two phenotypic markers in both M cells and epithelial cells adjacent to crypts, which lack the typical morphology of fully developed rabbit M cells, suggests that they correspond to immature M cells which by their location appear to derive directly from undifferentiated crypt stem cells and not from mature columnar enterocytes.     

Ultrastructural changes in the appendix of the Sauromatum guttatum inflorescence during anthesis

Summary The ultrastructure of the epidermal and sub-epidermal cells of the appendix of the Sauromatum guttatum inflorescence reveals developmental changes during anthesis. These changes precede, and probably make possible, heat and odor production. Two days before D-day (the day of heat production and inflorescence-opening) the mitochondria of the epidermis divide; apparent division of the amyloplasts was observed at the same time. The presence of lipid bodies and peroxisomes in the epidermis was clearly evident. On D-day, the epidermis becomes a continuous layer in which the cell walls separating two adjacent cells disappear. At the same time, in the sub-epidermal cells, the mitochondria and the amyloplasts undergo division. The mitochondria become electron-dense, and their DNA is clearly visible. On that day, lipids as well as starch are being depleted. The peroxisomes change in structure every day, from D-2 to D-day. It has also been demonstrated by histochemical techniques that during anthesis the activity of cytochrome c oxidase (3,3-diaminobenzidine as a substrate) decreases whereas the activity of NADH dehydrogenase [tetrazolium salts: nitro-blue tetrazolium chloride (NBT) or neotetrazolium chloride (NT) in the presence of NADH], increases. Oxygen consumption of isolated mitochondria from the D-day appendix was inhibited in the presence of the two tetrazolium salts to a different degree: oxidation of NADH in the presence of NBT was the most sensitive to inhibition, more so than the oxidation of malate and succinate. NT was less effective as an inhibitor in the presence of those three respiratory substrates.     

Predicting the Risk of Suicide by Analyzing the Text of Clinical Notes

We developed linguistics-driven prediction models to estimate the risk of suicide. These models were generated from unstructured clinical notes taken from a national sample of U.S. Veterans Administration (VA) medical records. We created three matched cohorts: veterans who committed suicide, veterans who used mental health services and did not commit suicide, and veterans who did not use mental health services and did not commit suicide during the observation period (n = 70 in each group). From the clinical notes, we generated datasets of single keywords and multi-word phrases, and constructed prediction models using a machine-learning algorithm based on a genetic programming framework. The resulting inference accuracy was consistently 65% or more. Our data therefore suggests that computerized text analytics can be applied to unstructured medical records to estimate the risk of suicide. The resulting system could allow clinicians to potentially screen seemingly healthy patients at the primary care level, and to continuously evaluate the suicide risk among psychiatric patients.     

Germinal centers and the B-cell system

Summary The migration pattern of germinal center cells of the rabbit appendix was studied and compared with that of appendix dome cells, spleen cells, thymus cells and thoracic duct lymphocytes. To discriminate T-and B-cell migration pathways, normal or T-cell-depleted rabbits were used as donors. Cell suspensions were labeled in vitro with ³H-leucine followed by intravenous transfer. The migration of labeled cells in lymphoid organs was studied using autoradiography, particular attention being paid to the spleen of the recipient. B-cells from the appendix dome, spleen and thoracic-duct lymph migrate to primary follicles or the corona of secondary follicles via thymus-dependent areas of peripheral lymphoid organs. In contrast, a B-cell subpopulation from the germinal centers of the appendix migrates to the center of splenic primary follicles and into germinal centers. The migration of germinal center cells to splenic follicle centers is not enhanced by specific antigens. The migration properties of B-cells, possibly changing during differentiation, may be instrumental in the two types of immune reactions, i.e., plasma-cell reaction and germinal-center reaction.     

兔阑尾中一种新的21kD的钙结合蛋白的纯化与鉴定

纯化与鉴定了Ｂ淋巴细胞中一种新的分子量为２１ｋＤ的钙结合蛋白（ＣａＢＰ２１）。兔阑尾淋巴细胞匀浆经热变性,Ｐｈｅｎｙｌ－Ｓｅｐｈａｒｏｓｅ与ＤＥＡＥ－Ｓｅｐｈａｒｏｓｅ柱层析,自每１ｋｇ细胞沉积物中获得ＳＤＳ－ＰＡＧＥ均一的ＣａＢＰ２１５．３ｍｇ。ＨＣｌ水解后的酸性氨基酸（Ａｓｐ＋Ｇｌｕ）含量为２６％。如同大多数钙结合蛋白一样,Ｎ末端封闭阻止其进行Ｅｄｍａｎ降解。ＣａＢＰ２１中疏水性氨基酸（计Ｇｌｙ,不计Ｔｒｐ）约占４６％,碱性氨基酸１０％,酸性氨基酸与极性氨基酸约４４％。ＣａＢＰ２１有较高的Ｓｅｒ、Ｔｙｒ含量。肽谱分析等确证ＣａＢＰ２１为２个相同或相似亚基二聚体。以ＡｒｓｅｎａｚｏⅢ作Ｃａ２＋结合分析表明每分子ＣａＢＰ２１可结合４分子Ｃａ２＋,对Ｃａ２＋的结合常数约为１０－５ｍｏｌ／Ｌ。各种性质表明ＣａＢＰ２１是一种不同于其他已知钙结合蛋白的新钙结合蛋白。     

控制野生物国际贸易, 保护地球生物多样性——CITES公约第十八次缔约方大会评述

濒危野生动植物种国际贸易公约(CITES公约)第十八次缔约方大会于2019年8月召开, 审议了56个附录修订提案和140多个工作文件, 延续了近年附录修订趋势, 但减缓了新物种列入附录速度, 明确了附录的适用、解释和执行, 设立了监管新规定, 还采纳了《CITES公约2020后战略愿景》。中国在会上树立了重视生态文明建设的负责任大国的正面形象, 中国提交的5项附录修订提案全部获得通过。     

阑尾杯状细胞类癌合并回盲部混合型腺神经内分泌癌1例病例报道并文献复习

目的:报道1例极为罕见的阑尾杯状细胞类癌(goblet cell carcinoid,GCC)合并回盲部混合型腺神经内分泌癌(mixed adenoneuroendocrine carcinoma,MANEC),以提高临床医师对本病的认识。方法:回顾性分析1例阑尾GCC合并回盲部MANEC患者的临床、病理特征、免疫组化及术后情况并进行文献复习。结果:该病例经病理切片会诊明确诊断为GCC,行右半结肠切除术后进一步诊断为回盲部MANEC,行1次FOLFOX化疗后,一般情况良好。结论:阑尾GCC合并回盲部MANEC是具有高度侵袭性的异质性恶性肿瘤,免疫组化局部Cg A和局部Syn阳性、Tang分类C组、临床分期IV期和非根治性手术为不良预后的危险因素。     

Development of dome epithelium in gut-associated lymphoid tissues: Association of IgA with M cells

Summary The dome epithelium (DE), which covers gutassociated lymphoid tissues (GALT) and provides both a protective barrier over lymphoid follicles and a route for antigen uptake from the gut, develops in rabbit appendix (caecum) during the first week of neonatal life. To determine if secretory immunoglobulins from maternal milk interact with this developing tissue, their interrelationships in neonatal rabbit appendix were examined by use of immunocytochemical techniques. The glycoprotein, secretory component, was not produced by neonatal rabbits less than 15 days old, since neither the membranous nor the free, secreted forms of maternal secretory component were associated with villi or DE of neonates. Immunoglobulin A (IgA), but neither IgG nor IgM, were noted on DE by light microscopy, even though IgG was abundant in the villus lamina propria and vascular spaces. The epithelial IgA was distributed, in a patchy pattern, across the upper dome surface of some two-day-old, and all five-and ten-day old nursing animals, but IgA was not on DE of rabbits prevented from nursing. Immunoelectron microscopy of appendix from nursed rabbits revealed IgA directly over the apical surface of M cells, where it formed a continous, thick coating without binding to adjacent immature absorptive cells; it was also within apical vacuoles of M cell cytoplasm. The distribution of IgA on the DE of rabbit appendices indicated that in differentiating GALT, maternal IgA reacted preferentially with M cells or pre-M cells, leading to speculation concerning a role for IgA in the development of GALT and in establishment of mucosal immune responses in neonates.In conducting the research described in this report, the investigators adhered to the standards set forth in the Guide for the Care and Use of Laboratory Animals (NIH Publication 85-23) as promulgated by the Committee on Care and Use of Laboratory Animals of the Institute of Laboratory Animal Resources, National Research Council, USAAbbreviations DE dome epithelium - GALT gutassociated lymphoid tissues - HRP horseradish peroxidase - IgA immunoglobulin A - SC secretory component The views of the authors expressed here do not purport to reflect the position of the Department of the Army or the Department of Defense     

Role of 57-72 loop in the allosteric action of bile salts on pancreatic IB phospholipase A2: Regulation of fat and cholesterol homeostasis

Mono- and biphasic kinetic effects of bile salts on the pancreatic IB phospholipase A2 (PLA2) catalyzed interfacial hydrolysis are characterized. This novel phenomenon is modeled as allosteric action of bile salts with PLA2 at the interface. The results and controls also show that these kinetic effects are not due to surface dilution or solubilization or disruption of the bilayer interface where in the mixed-micelles substrate replenishment becomes the rate-limiting step. The PLA2-catalyzed rate of hydrolysis of zwitterionic dimyristoylphosphatidylcholine (DMPC) vesicles depends on the concentration and structure of the bile salt. The sigmoidal rate increase with cholate saturates at 0.06 mole fraction and changes little at the higher mole fractions. Also, with the rate-lowering bile salts (B), such as taurochenodeoxycholate (TCDOC), the initial sigmoidal rate increase at lower mole fraction is followed by nearly complete reversal to the rate at the pre-activation level at higher mole fractions. The rate-lowering effect of TCDOC is not observed with the (62-66)-loop deleted ΔPLA2, or with the Naja venom PLA2 that is evolutionarily devoid of the loop. The rate increase is modeled with the assumption that the binding of PLA2 to DMPC interface is cooperatively promoted by bile salt followed by allosteric k_cat^?-activation of the bound enzyme by the anionic interface. The rate-lowering effect of bile salts is attributed to the formation of a specific catalytically inert E^?B complex in the interface, which is noticeably different than the 1:1 EB complex in the aqueous phase. The cholate-activated rate of hydrolysis is lowered by hypolidemic ezetimibe and guggul extract which are not interfacial competitive inhibitors of PLA2. We propose that the biphasic modulation of the pancreatic PLA2 activity by bile salts regulates gastrointestinal fat metabolism and cholesterol homeostasis.     

A novel antigen is common to the dome epithelium of gut- and bronchus-associated lymphoid tissues

Summary The dome epithelium (DE) covering bronchus- and gut-associated lymphoid tissues (BALT and GALT) is composed of columnar cells, groups of lymphocytes, M cells, and pre-M cells. Although the cell biology and immunologic processes of this tissue are likely important in the afferent arm of secretory immune responses, virtually nothing is known about biochemical constituents of the DE. Therefore, a monoclonal antibody, 30E5, was used to study the distribution of a novel antigen, common to dome epithelia of GALT and BALT. 30E5 was secreted by a hybridoma, prepared by fusing murine splenocytes, immunized against dome epithelial cells, with P3×68/Ag8 myeloma cells. Reactivity of antigens was defined by indirect immunocytochemistry on sections of rabbit tissues or with dissociated epithelial cells. In situ, 30E5-reactive antigen circumscribed each group of dome epithelial lymphocytes, most or all of which were T cells, in rabbit appendix, sacculus rotundus, cecal patch, Peyer's patch, and BALT. In the DE this antigen was associated with the apical surface and the supranuclear or perinuclear regions of epithelial cells, but it was not associated with epithelial cells of villi, epithelium, or with individual lymphocytes. In peripheral lymph nodes, spleen, and in domes and follicles of GALT or BALT, 30E5-reactive antigen was visualized in linear wisps, primarily in regions populated by thymocytes. In other adult tissues, 30E5-reactive antigen was associated with involuntary muscle, myoepithelial cells of lactating mammary gland and with what appeared to be neural dendrites; but it was not found in epithelia other than DE. In neonatal rabbit appendix, this antigen first appeared in the upper dome epithelium two days after birth, a period coinciding with T cell infiltration and M cell maturation. The histologic distribution of 30E5-reactive antigen suggested that it might be a contractile filament, a receptor, or a differentiation antigen. Since 30E5 was associated with DE of both GALT and BALT, results support the concept of a molecule common to all mucosa-associated lymphoid tissues.In conducting the research described in this report, the investigators adhered to standards set forth in the Guide for the Care and Use of Laboratory Animals (NIH Publication 85-23) as promulgated by the Committee on Care and Use of Laboratory Animals of the Institute of Laboratory Animal Resources, National Research Council, USALimited quantities of ascites containing monoclonal antibody 30E5 will be distributed to interested investigators until such time as the hybridoma is available from American Type Culture CollectionAbbreviations ABC avidin-biotin-horseradish peroxidase complex - BALT bronchus-associated lymphoid tissues - DMEM Dulbecco's modified Eagle medium - GALT gut-associated lymphoid tissues - DE dome epithelium - DEL dome epithelial lymphocytes - MAb monoclonal antibody - MALT mucosal-associated lymphoid tissues The views of the authors expressed here do not purport to reflect the position of the Department of the Army or the Department of Defense Send offprint requests to: Department of Experimental Pathology, Division of Pathology, Walter Reed Army Institute of Research, Washington, D.C. 20307-5100, USA