Antigen-presenting cell-T cell interaction in the chicken is MHC class II antigen restricted

The involvement of the MHC in the recognition of Ag by avian T lymphocytes was analyzed. PBL from chickens primed with keyhole limpet hemocyanin in vivo were induced to synthesize DNA in an in vitro response to specific Ag. Responding cells were T cells as judged by immunofluorescence staining. In vivo Ag-primed PBL were stimulated in vitro with specific Ag and further propagated in the presence of IL-2. Subsequent Ag-specific T cell proliferation required the presence of Ag-pulsed peripheral blood adherent cells (APC). T cell responses were restricted by the MHC of the APC; Ag presented by allogeneic APC did not support T cell proliferation. By using MHC-recombinant chicken lines, the gene products controlled by MHC class II loci were shown to restrict the T cell-APC interaction. This conclusion was substantiated by the inhibition of the Ag-specific T cell response by a mAb against chicken MHC class II gene products but not by a mAb against chicken MHC class I gene products.     

Primer protein of bacteriophage M2 exposes the RGD receptor site upon linking the first deoxynucleotide

Summary Using electroporation with the phage PRD1 genome, we set up a high-frequency DNA transfer system for a linear dsDNA molecule with 5-covalently linked terminal proteins. The transfer was saturated when more than 100 ng of PRD1 genome was used. Electroporation efficiency was about four orders of magnitude higher than that obtained with transfection. Removal of the terminal protein abolished plaque formation, which could not be rescued by supplying the terminal protein or phage DNA polymerase or both in trans.     

Hydrolysis of phospholipid monolayers by human spermatozoa. Inhibition by male contraceptive gossypol

Monomolecular films of phospholipid were used to study the interaction of intact human spermatozoa with model membranes. Exclusively with negatively charged phosphatidylglycerol monolayers rapid penetration of spermatozoa into the monolayer with subsequent hydrolysis of the lipid was triggered by the addition of 5 mM calcium into the medium. The results suggest the localization of a calcium-dependent phospholipase A2 at the outer acrosomal or plasma membrane of human spermatozoa with its active site exposed to the external environment. Preincubation of the cells with 100 microM gossypol completely abolished the ability of human spermatozoa to hydrolyze or penetrate monolayers of phosphatidylglycerol. The inhibition of the phospholipase activity by gossypol may contribute to the unknown contraceptive mechanisms of this non-steroidal male antifertility agent.     

Increased endogenous retroviral gene expression is a consequence of lymphocyte activation

Plasma cells of line 151(5) chickens have been shown to express elevated levels of endogenous retroviral envelope glycoprotein (VEG), measured relative to levels expressed by both immature B cells and resting peripheral B lymphocytes. In this study we analyzed the relationship between peripheral blood lymphocyte (PBL) maturation and the level of VEG expression. A culture system was developed that would support maturation of pokeweed mitogen-activated peripheral B lymphocytes. As analyzed by cytofluorometry, both Ig+ and Ig- lymphoblasts present in the pokeweed mitogen-stimulated cultures expressed detectable levels of VEG in contrast to bursacytes and PBL. Similarly, Ig- blasts, which were present in concanavalin A-stimulated cultures of PBL and presumed to represent activated T cells, were also positive for the expression of VEG. Immature T cells, i.e., thymocytes, although negative by immunofluorescence analysis, expressed VEG at levels that were detectable by radioimmunochemical techniques. These results indicate that T cells as well as B cells constitutively express VEG, and that mitogenic activation of the resting lymphocyte induces an increase in VEG expression.     

Muscle strength and mineral densities in the mandible

Bone mineral density (BMD) in the femoral neck and lumbar spine was measured for 355 postmenopausal 48- to 56-year-old women and the BMD in five different regions in the mandible for 77. All 355 women were also classified according to the size of the masseter muscle. Both skeletal measures and the BMD of the buccal cortex distally from the foramen mentale were compared with the size of the masseter muscle. This study indicates that functional stress, caused by the masseter muscle, is involved in maintaining bone mineral density in edentulous regions of the mandible. Those individuals who are physically active or are bruxists may lose less mineral, after extractions of teeth, from those regions of the jaw bones where the muscles are attached.     

Growth patterns in young adult monozygotic twin pairs discordant and concordant for obesity.

Weight discordance is very rare in monozygotic (MZ) twin pairs; when found, however, such pairs are advantageous in the search for either environmental or epigenetic causes and consequences of obesity. We analyzed the growth patterns of young adult MZ pairs discordant and concordant for obesity. Screening 5 consecutive birth cohorts (1975-1979) of 22- to 27-year-old Finnish twins (the FinnTwin16 study), we found 14 obesity discordant (Body Mass Index [BMI] difference > or = 4 kg/m2) MZ pairs out of 658. Ten pairs participated in clinical studies. Nine concordant pairs (BMI difference < or = 2 kg/m2) were examined as controls. Lifetime measured heights and weights recorded in hospitals and health centers were traced manually. Height development was similar in all the co-twins of both groups. The weight differences between the co-twins of the discordant pairs began to emerge at 18 years leading to an average discordance of 16.4 kg, 5.6 kg/m2 (p for both = .005) at 25.7 years. The heavier co-twin weighed 221 g (p = .066), 1.0 kg/m2 (p = .01) more already at birth than the leaner, but the differences waned by 6 months of age and reappeared only after adolescence. Both the leaner and the heavier co-twins of the discordant pairs weighed more than expected by the singleton reference values (Cole et al., 1998) after 8 years. The concordant co-twins, on the other hand, grew similarly and after 6 months, their mean growth was not distinguishable from the singleton patterns. Young adulthood represents a critical period of gaining weight irrespective of genetic background in this twin sample.     

Complexing of glycofuranosides with calcium ion,and its effect on their acid-catalysed solvolysis

Stability constants for the calcium-ion complexes of several methyl aldo-furanosides have been determined in aqueous solution by using a potentiostatic technique with an electrode that is selective for calcium ions. The results obtained have been verified by examining the chromatographic behaviour of the compounds on a strong cation-exchange resin in the Ca²⁺ form. The rate constants for the acid-catalyzed hydrolysis and methanolysis of a few 4-chlorophenyl aldofuranosides having different complexing abilities have been determined at various concentrations of calcium chloride. The dependences of the observed salt effects on the complexing ability of the substrate are discussed.     

Effects of acute CS2 intoxication on liver protein and drug metabolism

Rats pretreated with phenobarbitone and their controls were exposed to 0.15% atmospheric CS₂ for 2 h. Liver protein metabolism and microsomal drug metabolizing enzyme activities were analyzed 1, 4 and 46 h later. In the pretreated rats the [¹⁴C]leucine uptake was at first inhibited, then liver RNA tended to increase. This increase was followed by a decline in the [¹⁴C]leucine uptake, while RNA content diminished to the control level. In the control rats (not pretreated with phenobarbital) the effects of CS₂ on liver protein metabolism were less; only at 4 h after the exposure was liver RNA increased and [¹⁴C]leucine uptake slightly stimulated. In the pretreated rats CS₂ had decreased microsomal P-450 by about 50% at 1 and 4 h, and the activity of 7-O-dealkylase of ethoxycoumarin had decreased even more. The measurable UDPglucuronosyltransferase of the liver microsomes of the pretreated rats had increased by 26% at 1 h and by 80% at 4 h after the CS₂ exposure. The in vivo activation of microsomal UDPglucuronosyltransferase may result from a stimulated lipid peroxidation of reticuloendothelial membranes by CS₂ metabolites in vivo, as suggested by the diene conjugation spectra. In control rats CS₂ depressed only the ethoxycoumarin deethylase activity. All the microsomal changes caused by CS₂ exposure were restored within 46 h.It is suggested that the different action of CS₂ on the liver protein metabolism of rats pretreated with phenobarbitone and controls results from the different stage of protein turnover in the two groups, i.e. in the barbituratetreated animals there is a phase of increased protein synthesis and accordingly the protein turnover is more sensitive to the action of CS₂.