Intestinal barrier function in response to abundant or depleted mucosal glutathione in Salmonella-infected rats

Background  

Glutathione, the main antioxidant of intestinal epithelial cells, is suggested to play an important role in gut barrier function and prevention of inflammation-related oxidative damage as induced by acute bacterial infection. Most studies on intestinal glutathione focus on oxidative stress reduction without considering functional disease outcome. Our aim was to determine whether depletion or maintenance of intestinal glutathione changes susceptibility of rats to Salmonella infection and associated inflammation.     

Absolute versus per unit body length speed of prey as an estimator of vulnerability to predation

To study whether absolute (m/s) or relative (body lengths/s) speed should be used to compare the vulnerability of differently sized animals, we developed a simple computer simulation. Human 'predators' were asked to 'catch' (mouse-click) prey of different sizes, moving at different speeds across a computer screen. Using the simulation, a prey's chances of escaping predation depended on its speed (faster prey were more difficult to catch than slower prey of the same body size), but also on its size (larger prey were easier to catch than smaller prey at the same speed). Catching time, the time needed to catch a prey, also depended on both prey speed and prey size. Relative prey speed (body lengths/s or body surface/s) was a better predictor of catching time than was absolute prey speed (m/s). Our experiment demonstrates that, in contrast to earlier assertions, per unit body length speed of prey may be more 'ecologically relevant' than absolute speed. Copyright 1998 The Association for the Study of Animal Behaviour.     

Porcine CD58: cDNA cloning and molecular dissection of the porcine CD58-human CD2 interface

The porcine ligands of human CD2 remain unknown in xenotransplantation despite being an important pathway of T cell costimulation. Of the two main candidates, i.e., CD48 and CD58, the cDNA of the most likely ligand poCD58 was cloned from CD48-negative endothelial cells costimulating human CD4(+) T cells through the CD2 pathway. The deduced protein sequence is 244 residues long and is 43% homologous to the human sequence. Based on similarity between porcine and human CD58 external V-set Ig-type domains, a structural model of poCD58-huCD2 interaction was built. Most of the charged residues located at the interface with huCD2 are highly conserved. Six putative hydrogen bonds between poCD58 and huCD2 were identified; five involve the same residues as in the syngeneic combination while the sixth is formed between an additional tyrosine in poCD58 and Arg48 in huCD2, increasing the complementarity between the two molecules. These structural data will help us to develop poCD58 blocking agents for xenotransplantation.     

Human choriocarcinoma cell resistance to natural killer lysis due to defective triggering of natural killer cells

The trophoblast, the outermost layer of the human placenta, lacks expression of the classical human leukocyte antigen (HLA) class I molecules. This prevents allorecognition by T cells but raises the question of what protects the trophoblast from natural killer (NK) cells. In a previous study, we have shown that choriocarcinoma cell (CC) resistance to NK lysis was mainly independent of HLA class I molecules. In the present study, we postulated that CC may prevent activation of NK cells by failing to stimulate their triggering receptors (TR). To test this hypothesis, we evaluated the lysis of JAR and JEG-3 CC after effective cross-linking and activation of NK cells by means of lectins or antibodies. Our results show that NK-resistant CC were sensitive to lysis by unstimulated peripheral blood lymphocytes in the presence of phytohemagglutin (PHA), to antibody-dependent cell cytotoxicity in presence of anti-Tja antibodies, and to monoclonal antibody redirected killing using anti-TR antibodies anti-CD16 and anti-CD244/2B4. Finally, CC fail to express CD48, the ligand for CD244/2B4. These results indicate that the resistance of CC to lysis results primarily from defective NK cell activation, at least partially due to the lack of expression of ligands, such as CD48, involved in the triggering of NK cells.     

Characterization of the human syncytiotrophoblast plasma membrane associated components

A purification procedure of synctiotrophoblast plasma membrane (STPM) has previously been described. We now report a further characterization of their associated components. By immunochemical analysis two groups of proteins were found. The first fraction solubilized by chaotrope treatment was made up with a complex of IgG, albumin, transferrin and alpha-fetoprotein. The second fraction, insolubilized by KCl-treatment but by detergents, did not react with antisera to human proteins; it contained human chorionic gonadotropin and placental lactogen. The amino acid, carbohydrate and lipid content of STPM were determined. High galactosyl- and sialyl-transferase activities were found in purified STPM. The role of these various components on the acceptance of the fetal allograft is discussed.     

A simple and sensitive solid-phase radioimmunoassay for measuring the transferrin content of human biological fluids: its application to seminal plasma

A highly sensitive and reproducible radioimmunoassay was established to detect transferrin in human fluids. By this technique, applied to seminal fluid, transferrin levels (micrograms/ml) were found in normozoospermic individuals (64.49 +/- 25.41) at level higher than in oligozoospermic (38.93 +/- 21.35), azoospermic (19.49 +/- 10.23), or vasectomized (19.61 +/- 8.95) subjects. A relationship between transferrin and spermatozoid concentration in sperm was shown. These results reinforce previous findings that seminal transferrin can be used as a reliable clinical marker of Sertoli Cell function.