Fetal antigens as tumor growth enhancing factors in Yoshida's tumor rats

Malignant neoplastic cells have been shown to have some antigenic features identical to those of embryonic cells. Since several antigens are likely to be shared by both embryonic cells and neoplastic tissue, we tried to understand the meaning of the appearance of such antigens and the type of effect that the immunization with embryonic antigens would have on the survival of Yoshida's tumor rats. Wistar rats were immunized with fetal antigens by fetal cells (1.5 x 10(6)) suspended in 0.5 ml of Hanks solution plus an equal volume of Freund adjuvant, were injected in hind footpads, i.p. and i.m., respectively, for active immunization. Rabbit antigen sera were used for passive immunization. All animals presented ascites and tumor growth. Animals immunized by means of fetal cell antigens showed a mean survival rate after neoplastic transplant of 14 days. Animals that received rabbit immune serum showed a mean survival rate after neoplastic transplant of 17 days. The immunization by means of fetal antigens elicited a scanty effect on the survival of Yoshida's tumor transplanted rats. It can be concluded that antibodies, which are able to cross react with neoplastic cells, do not have cytotoxic effect and do not interfere with the survival of the neoplastic transplanted animals. Therefore, fetal antigens are likely able to carry out an immunosuppressive action. The fact that they appear on neoplastic cells could be seen as a metabolic modification effect or as a growth enhancing factor.     

Effects of modulation of the redox system on endogenous lipoperoxidation in the rat central nervous system

In this study we have measured malonaldehyde (MDA) as an index of endogenous lipoperoxidation, the latter being a relevant aspect of oxidative stress that occurs in different neuronal systems. Our results clearly demonstrate that in physiological conditions specific neuronal systems exhibit a different rate of MDA formation among which substantia nigra neurons show a particular vulnerability to oxidative stress. Chronic ethanol treatment significantly enhances MDA production, particularly at the level of cholinergic structures (septum) as well as in the dopaminergic system (substantia nigra) and cortex. On the other hand, treatment with glutathione is able to decrease MDA formation, pointing out the possibility of an exogenous modulation of redox balance in brain cells.     

Molecular phylogeny of the springhare, Pedetes capensis, based on mitochondrial DNA sequences

The phylogenetic position of the Pedetidae, represented by a single species Pedetes capensis, is controversial, reflecting in part the retention of both Hystricomorphous and Sciurognathous characteristics in this rodent. In an attempt to clarify the species evolutionary relationships, mtDNA gene sequences from 10 rodent species (representing seven families) were analyzed using phenetic, parsimony, and maximum-likelihood methods of phylogenetic inference; the rabbit, Oryctolagus cuniculus (Order Lagomorpha), and cow, Bos taurus (Order Artiodactyla), were used as outgroups. Investigation of 714 base pairs of the protein-coding cytochrome b gene indicate strong base bias at the third codon position with significant rate heterogeneity evident between the three structural domains of this gene. Similar analyses conducted on 816 base pairs of the 12S rRNA gene revealed a transversion bias in the loop sections of all taxa. The cytochrome b gene sequences proved useful in resolving associations between closely related species but failed to produce consistent tree topologies at the family level. In contrast, phylogenetic analysis of the 12S rRNA gene resulted in strong support for the clustering of Pedetidae/Heteromyidae/Geomyidae and Muridae in one clade to the exclusion of the Hystricidae/Thryonomyidae and Sciuridae, a finding which is concordant with studies of rodent fetal membranes as well as reproductive and other anatomical features.      

Stereoselectivity for the (R)-Enantiomer of HA-966 (l-Hydroxy-3-Aminopyrrolidone-2) at the Glycine Site of the N-Methyl-d-Aspartate Receptor Complex

HA-966 (1-hydroxy-3-aminopyrrolidone-2) is an antagonist at the glycine allosteric site of the N-methyl-D-aspartate receptor ionophore complex. Unlike presently known glycine antagonists, HA-966 is chiral. We report stereoselectivity for the (R)-enantiomer at the glycine antagonist site. In [3H]glycine binding, the (R)-enantiomer has an IC50 of 4.1 +/- 0.6 microM. The racemic mixture has an IC50 of 11.2 +/- 0.5 microM, whereas (S)-HA-966 has an IC50 greater than 900 microM. In glycine-stimulated [3H]1-[1-(2- thienyl)cyclohexyl]piperidine binding, the (R)-enantiomer inhibits with an IC50 of 121 +/- 61 microM, whereas the racemic mixture has an IC50 of 216 +/- 113 microM and (S)-HA-966 is inactive. The inhibition by (R)-HA-966 can be prevented by the addition of glycine. (R)-HA-966 and racemic HA-966, but not (S)-HA-966, also prevent N-methyl-D-aspartate cytotoxicity in cortical cultures. The (R)-enantiomer and, less potently, the (S)-enantiomer inhibit N-methyl-D-aspartate-evoked [3H]norepinephrine release from rat hippocampal slices (IC50 values of about 0.3 mM and 1.6 mM, respectively), but only the inhibition by (R)-HA-966 is reversed by added glycine. In glutamate-evoked contractions of the guinea pig ileum, (R)-HA-966 causes a glycine-reversible inhibition (IC50 of about 150 microM), whereas (S)-HA-966 is much less potent (IC50 of greater than 1 mM). These results demonstrate stereoselectivity of the glycine antagonist site of the N-methyl-D-aspartate receptor complex in a variety of tissues and assays. The stereoselectivity also confirms the specificity of N-methyl-D-aspartate receptors in glutamate-evoked contractions of the guinea pig ileum, and supports their similarity to central N-methyl-D-aspartate receptors.     

Oligonucleotides Quality Control Analysis in Free Solution by Capillary Electrophoresis at Acidic pH

Abstract

A new method for fast, automated and inexpensive oligonucleotides analysis by capillary electrophoresis at low pH is presented. This method does not need any sieving media to resolve a mixture of polynucleotides which are analysed in free solution and separated on the base of composition and not length. This technique has been used to test a large set of standard and modified oligonucleotides thus to be applied in oligos routine quality control.     

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.     

A multi-step approach to time series analysis and gene expression clustering

MOTIVATION: The huge growth in gene expression data calls for the implementation of automatic tools for data processing and interpretation. RESULTS: We present a new and comprehensive machine learning data mining framework consisting in a non-linear PCA neural network for feature extraction, and probabilistic principal surfaces combined with an agglomerative approach based on Negentropy aimed at clustering gene microarray data. The method, which provides a user-friendly visualization interface, can work on noisy data with missing points and represents an automatic procedure to get, with no a priori assumptions, the number of clusters present in the data. Cell-cycle dataset and a detailed analysis confirm the biological nature of the most significant clusters. AVAILABILITY: The software described here is a subpackage part of the ASTRONEURAL package and is available upon request from the corresponding author. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.