Ganglioside GM1 attenuates scopolamine-induced amnesia in rats and mice

We evaluated ethanol- and HCl-induced mucosal damages in developing rats. The degree of damage induced by ethanol and HCl was greatest in 1-week-old rats and decreased significantly with age until 4 weeks; thereafter it increased again. To evaluate the effect of weaning on the maturational changes in mucosal defense, we compared ethanol-induced mucosal damage among three groups of newborn rats: (1) receiving milk only; (2) receiving only rat chow from 14 days of age, and (3) having free access to milk and chow. There were no significant differences at 18 and 21 days of age. The mucus thickness increased with age until 8 weeks and was not affected by weaning. In conclusion, developmental changes occur in gastric mucosal protection in rats. Weaning does not have a significant effect on these changes.     

MHC class I genes in a New World primate, the cotton-top tamarin (Saguinus oedipus), have evolved by an active process of loci turnover

Lymphocytes of a New World primate, the cotton-top tamarin (Saguinus oedipus), express classical G-related major histocompatibility complex (MHC) class I molecules with unusually limited polymorphism and variability. Three G-related loci, an F locus, an E locus, and two pseudogenes (So-N1 and So-N3) have been identified by cDNA library screening and extensive PCR analysis of both cDNA and genomic DNA from the cotton-top tamarin. Furthermore, each genus of the subfamily Callitrichinae (tamarins and marmosets) appears to express its own unique set of MHC class I genes, likely due to a rapid turnover of loci. The rapid emergence of unique MHC class I genes in the Callitrichinae genera, resulting from an active process of duplication and inactivation of loci, may account for the limited diversity of the MHC class I genes in the cotton-top tamarin. To determine the nature of the entire complement of MHC class I genes in the cotton-top tamarin, we synthesized a genomic DNA library and screened it with MHC class I-specific probes. We isolated nine new MHC class I pseudogenes from this library. These newly isolated tamarin G-related MHC class I pseudogenes are not closely related to any of their functional counterparts in the tamarin, suggesting that they do not share a recent common ancestral gene with the tamarin's currently expressed MHC class I loci. In addition, these tamarin sequences display a high rate of nonsynonymous substitutions in their putative peptide binding region. This indicates that the genes from which they have derived were likely subject to positive selection and, therefore, were once functional. Our data support the notion that an extremely high rate of loci turnover is largely responsible for the limited diversity of the MHC class I genes in the cotton-top tamarin.     

Polymers in hernia repair–common polyester vs. polypropylene surgical meshes

Within the last years meshes have become essential for the repair ofabdominal wall hernias. While the type of mesh obviously influencesthe clinical result, the selection of the best suitablemesh-modification should have favourable effects onto the rate ofcomplications. Available surgical meshes mainly differ in the typeand amount of the basic polymers. The most common meshes are madeeither out of monofilament polypropylene (PP) or multifilamentpolyester (PET). In the following contribution we studied thefunctional and histological results of standard and commerciallyavailable surgical meshes: a standard heavyweight, large pore-sizedPP-mesh (Prolene®), a heavyweight, large pore-sized PET-mesh(Parietex®, coated with bovine collagen) and a low weightsmall pore-sized PET-mesh (Mersilene®) in a standardised ratmodel. The meshes are studied by three dimensional stereography,tensiometry, light-(LM) and transmission electron microscopy (TEM),as well as morphometry over implantation intervals of 3, 7, 14, 21and 90 days. The results proved marked differences between thetested meshes in regard to textile properties, the mechanicalfunction (tensile strength, abdominal wall mobility), as well as thehistologically proved tissue reaction. Both heavyweight meshes (PPand PET) revealed an enormous and most similar strength whereas thelow weight PET-mesh primarily showed a considerable increase offlexibility. Despite their different structures and their diversehistological response all tested meshes led to a similar andsignificant reduction of the abdominal wall flexibility. However, thelocal tissue response of the interface mesh/recipient tissuesrevealed a significant reduction of the acute inflammatory activity anda significant decrease of connective tissue formation in the case ofthe low weight PET-mesh Mersilene® compared to both heavyweightmesh-modifications. Mersilene® showed an excellent andrelatively inert tissue reaction of the interface compared toProlene® and Parietex®. Modifications of the mesh-structure(e.g. larger pores) should improve the functional results, inparticular, abdominal wall flexibility. However, the use of PET inhernia surgery is at least questionable in respect to the obligatelong-term degradation of this polymer.     

Apomorphine-induced yawning in the rat: influence of fasting and time of day

Yawning behavior is an experimental tool to study physiological responses, to elucidate the mechanisms of action of some drugs and hormones, and it is also a paradigm for some diseases and for dopamine (DA) agonists' clinical use. In this study, the effects of 24- and 48-h fasting as well as the influence of the light-dark cycle on apomorphine (APO)-induced yawning were evaluated. Initially, control and 48-h-fasted adult male rats were tested for yawning induced by APO (50, 100, 150 micrograms/kg, SC). The most effective dose tested was 100 micrograms/kg. Fasting significantly lowered yawning in all doses tested. Comparison between 24- and 48-h-fasted rats for APO (100 micrograms/kg)-induced yawning showed no significant difference between groups. Ad lib-fed groups were tested for APO (100 micrograms/kg)-induced yawning in both the light and in the dark phases of the cycle. Total number of yawnings increased significantly in the dark period. The present data show that fasting reduces and dark period increases APO-induced yawning in rats, suggesting that these conditions modulate the expression of this behavior.