Neuroendocrine changes in colon of mice with a disrupted IL-2 gene

Neuroendocrine peptides have a variety of physiological functions in the gastrointestinal tract. This study was carried out to investigate the impact of IL-2 deficiency on the neuroendocrine system in normal colon, and the neuroendocrine changes during colonic inflammation. Mice with homozygous disrupted IL-2 gene (IL-2-/-) spontaneously developed a bowel disease with similarities to human ulcerative colitis. Different types of colonic endocrine cells and myenteric nerves were analysed in the IL-2-/- mice using immunomorphometry. The neuropeptide contents in the colonic tissues were determined by radioimmunoassay. Age-matched healthy IL-2+/- and IL-2+/+ mice served as controls and the colonic IL-2 levels were compared between these two groups of mice by ELISA. Our data showed that less than half the amount of IL-2 was synthesized in the colon of IL-2+/- mice compared with the IL-2+/+ wild-type mice. Two major differences in the neuroendocrine colon were found between the mice with an intact and disrupted IL-2 gene. One was age-related. The frequencies of various endocrine cells and myenteric nerves increased with age in the IL-2+/+ mice. However, no such increases were seen in the mice with a disrupted IL-2 gene. Instead, the volume densities of enteroglucagon, serotonin cells and substance P (SP), vasoactive intestinal polypeptide (VIP) and total myenteric nerves were lower in the older IL-2+/- and IL-2-/- mice compared with the wild type. The other was disease-related. Polypeptide YY (PYY) cells and tissue levels of PYY, SP and VIP were significantly decreased in the IL-2-/- mice during the course of bowel inflammation compared with the healthy IL-2+/- and IL-2+/+ controls. These findings indicate that colonic neuroendocrine alterations did occur in the mice with a disrupted IL-2 gene and diminished local IL-2 level, suggesting a role of IL-2 in the regulation of the neuroendocrine system and a prevalent interaction between the immune and neuroendocrine systems in normal colon. On the other hand, there were some changes that seemed to correlate with the bowel inflammatory process. They might be associated with the impaired function in inflamed gut and contribute to the development and/or prolongation of disease.     

Differentiation of human single-positive fetal thymocytes in vitro into IL-4- and/or IFN-{gamma}-producing CD4+ and CD8+ T cells

In this study we have investigated the capacity of human fetalthymocytes to differentiate in vitro into subsets of T cellswith polarized T_h1 or T_h2 cytokine profiles. Stimulation offreshly isolated human fetal thymocytes with anti-CD3 mAb, cross-linkedonto CD32,CD58,CD80-expressing mouse fibroblasts and subsequentculture in the presence of exogenous rIL-2 for 6 days, inducedthe production of both IL-4 and IFN-, which was mainly producedby CD4⁺ single-positive (SP) and CD8⁺ SP cells respectively.Addition of rIL-4 during priming augmented IL-4 production incultures of human fetal thymocytes, which was mainly due toan increased production of IL-4 by CD8SP cells. In contrast,addition of IL-4 to the cultures only slightly enhanced IL-4production and had little effect on frequencies of IL-4-producingCD4SP cells. Both CD4SP and CD8SP cells produced IL-5, IL-10and IL-13 at comparable levels, following priming in the presenceof rIL-4. Priming in the presence of rIL-12 strongly enhancedthe production of IFN- in both CD4SP and CD8SP cells. No correlationbetween expression of CD27, CD30 and CD60, and a particularcytokine profile of differentiated thymocytes could be demonstrated.Together, these results demonstrate the full capacity of fetalhuman thymocytes to differentiate into cytokine-producing Tcells in a priming milieu with appropriate stimulatory moleculesand exogenous cytokines. In addition, CD4SP thymocytes rapidlydifferentiate into polarized T_h2 cells following stimulationin vitro in the absence of exogenous rIL-4.     

甘草黄酮抗实验性心律失常的作用

甘草黄酮（ｇｌｙｃｙｒｒｈｅｉｃｂｒｓｓ．ＧＢ）２ｍｇ／ｋｇ能明显对抗乌头碱２０μｇ／ｋｇ，ＢａＣｌ２２ｍｇ／ｋｇ和结扎左冠状动脉前降支诱发大鼠的室性心律失常。甘草黄酮也能明显对抗ＣａＣｌ２－Ａｃｈ（ＣａＣｌ２０．６％＋Ａｃｈ０．００２５％）混合液诱发小鼠心房纤颤或扑动，ＧＢ对大鼠心电图实验，证明了有负性频率作用，负性传导作用，这些作用可能是ＧＢ抗心律失常作用的药理基础。     

Relations between chronic stimulation-induced changes in contractile properties and the Ca2+-sequestering system of rat and rabbit fast-twitch muscles

This study compares changes in contractile properties, Parvalbumin content, and Ca²⁺-uptake by the sarcoplasmic reticulum (SR) of low-frequency stimulated rat and rabbit tibialis anterior (TA) muscles. Time to peak tension increased 1.8-fold in 35-day stimulated rabbit TA, while no change occurred in rat TA. Isometric twitch tension increased 2-fold in rabbit TA, but was unaltered in rat TA. Parvalbumin (PA) content was more than 90% reduced in rabbit TA, but only 60% in rat TA after 35 days. At this time, PA content of the stimulated rat TA was still higher than that of normal rabbit TA. Taking into account the suggested role of PA as a cytosolic Ca²⁺ buffer, its decrease could lead to an impaired free Ca²⁺-decay with a prolonged active state and a higher tension output during a single twitch. This would explain why chronic stimulation led to an increase in isometric twitch tension in rabbit TA, but not in rat TA. The 1.6-fold rise in half-relaxation time of 35-day stimulated rat and rabbit TA most likely resulted from a 50% reduced Ca²⁺-uptake by the SR, due to a still unknown modification of the Ca²⁺-transport ATPase.     

Subchronic Toxicity of 2,4,4'-Trichlorobiphenyl in the Rat Liver: An Ultrastructural and Biochemical Study

2,4,4'-Trichlorobiphenyl or PCB congener 28 was given to Sprague-Dawley weanling rats and the experimental diets were prepared by mixing the congener in 4% corn oil. The congener was administered to animals placed in four groups, each comprising 10 males or females. The diets contained 0.05, 0.5, 5, or 50 ppm congener. The fifth or control group comprised animals that received diets mixed with corn oil. Thirteen weeks after commencement of dosing, animals were euthanized and liver specimens were harvested from the animals and prepared for electron microscopy and biochemical analyses. The hepatocyte architectural modifications included an augmentation of SER profiles and an elevation of peroxisome numbers in animals regardless of gender, and mitochondrial abnormalities in the females only. Mitochondrial aberrations consisted of abnormal shapes and cristae in atypical orientation. The alterations were revealed in animals of the 5-and 50-ppm groups and were more extensive in the females. Ethoxyresorufin-O-de-ethylase activity was significantly high in the animals of the 50-ppm group. The results suggest that the female rats were more sensitive than the males to congener 28, and the no observable adverse effect level (NOAEL) was believed to be 0.5 ppm for the congener.     

Interferon-α activates cytotoxic function but inhibits interleukin-2-mediated proliferation and tumor necrosis factor-α secretion by immature human natural killer cells

Natural killer (NK) cells play an important role in host defense mechanisms against infection and neoplasia. Interferon- (IFN-) has been shown to activate NK cells and to augment their cytotoxic activity, albeit its role in the maturation pathway of NK cells has not been elucidated. The present study examined whether IFN- activates the immature NK subset (Free cells) to become cytotoxic and also ascertained whether IFN- uses the same pathway of activation as that mediated by interleukin-2 (IL-2). Incubation of sorted Free cells overnight with IFN- resulted in augmentation of their cytotoxic function against NK sensitive target cells. The enhanced cytotoxic activity was not accompanied by a new recruitment of NK-target binder cells but by an increase in the frequency of killer cells in the conjugate fraction. Activation of the Free subset by IFN- resulted in upregulation of CD69, CD11b, and CD2 surface expression and stimulated secretion of IFN-. Unlike IL-2, IFN- did not stimulate the Free cells to proliferate or secrete TNF- and activation of cytotoxicity and modulation of surface antigens by IFN- were independent of TNF-. The failure of IFN- to stimulate secretion and proliferation by Free cells appeared to be mediated by negative signals. This was corroborated in experiments demonstrating that when Free cells were cultured with both IFN- and IL-2, a significant inhibition was observed for both the IL-2 dependent secretion of TNF- and proliferation. These results demonstrate that IFN- serves as both an activator and a regulator of NK function. Further, activation of the immature Free NK cells by IL-2 and IFN- proceeds by TNF--dependent and independent pathways, respectively. The findings also support our contention that the mechanism of activation of the cytotoxic machinery of NK cells is not linked to the mechanism of activation of cytokine secretion and/or proliferation.Abbreviations used IFN interferon - IL interleukin - PBL peripheral blood leukocytes - PE phycoerythrin - PE-GAM PE-conjugated Fab2 goat anti-mouse IgG - NK natural killer - NRS normal rabbit serum - TNF tumor necrosis factor - FCS fetal calf serum - FITC fluorescein isothiocyanate - PBS phosphate-buffered saline - MACS magnetic cell sorting - ELISA enzyme-linked immunosorbent assay - BSA bovine serum albumin - PKC protein kinase C - mAb monoclonal antibody - PBMC peripheral blood mononuclear cells - BCLL B-chronic lymphocytic leukemia - E effector - T target     

人大脑内部微血管构筑——组织化学显示法研究

本文应用碱性磷酸酶组织化学对血管内皮的染色方法,光镜观察了3例人大脑内部的微血管构型。结果,皮质短动脉进入皮质内的分枝去向有:1.皮质返枝;2.水平枝;3.下降支。皮质长动脉末端的分枝类型分为:1.血管栅栏样分枝型;2.烛台样或小锚样分枝型;3.树根样分枝型。看到了从微动脉、毛细血管到微静脉的连续性通路。论述了皮质动脉与静脉之间在形态学方面的差别及皮质内血管吻合的几种形式,为更好地理解大脑皮质内微循环类型提供了形态学依据。     

Production and detection of monoclonal anti-idiotype antibodies directed against a monoclonal anti-beta-adrenergic ligand antibody

A new method has been developed to raise monoclonal anti-idiotypic antibodies. Monoclonal anti-idiotypic antibodies were obtained by fusion of NS-1 myeloma cells with splenocytes of mice immunised by intravenous injections of fixed hybridoma cells bearing a monoclonal antibody specific for beta-adrenergic ligands. New screening tests were developed to analyse the resulting hybridoma supernatants for different anti-idiotypic properties. Among 23 hybridoma supernatants recognising the idiotype, 6 were found to inhibit hapten binding and 3 of these recognised beta-adrenergic receptors.     

A general study of the binding and separation in partition affinity ligand assay. Immunoassay of beta 2-microglobulin

Partitioning in aqueous 2-phase systems was used to separate free and bound ligand in an immunoassay for beta 2-microglobulin. In order to get efficient separation in the phase system, the antibodies were modified to favour their partition in a different phase from that of antigen. However such modification of antibodies significantly decreased their binding capacity. This was overcome by using antibodies bound to previously modified staphylococci, which had proper partitioning behaviour. Alternatively, antibodies conjugated with biotin could be used in combination with modified avidin. This paper presents a method for the evaluation of data from immunoassays whereby 2-phase systems have been used to separate free and bound antigen.     

MR properties of excised neural tissue following experimentally induced demyelination

Changes in the magnetic resonance (MR) parameters of demyelinated neural tissue were measured in vitro using an experimental animal model. A tellurium (Te) diet was applied to weanling rats to induce the demyelination process in the sciatic nerve. The quantitative MR parameters, such as T(1), T(2) relaxation time constants and magnetization transfer (MT) were measured each day after applying the Te diet (up to 7 days) and were found to be substantially different from those of normal nerves. An increase in the average T(1) and T(2) was observed along with a decrease in the MT ratio (MTR) and the quantitative MT parameter M(0B), which describes the semisolid pool of protons. Most of the MR parameters correlated very well with the myelin fraction of neural tissue evaluated by quantitative histopathology. The T(2) relaxation spectrum provided the most efficient quantitative assessment of changes in neural tissue microstructure and its analysis resulted in a powerful tool to distinguish the processes of demyelination and inflammation. In comparison, the MT measurements were less successful.