Inmunosenescencia prematura en ratones triple-transgénicos para la enfermedad del Alzheimer

Introduction

A deterioration of the neuroimmunoendocrine network has been observed in Alzheimer's disease (AD). However, the peripheral immune response has hardly been investigated in this pathology. Since some immune function parameters have been established as good markers of the rate of ageing, and can predict longevity, the aim of the present work was to study some of these functions in splenic leucocytes in transgenic mice for AD of different ages.

Material and methods

Young female (4 ± 1 months), adult (9 ± 1 months), and mature (12 ± 1 months) triple-transgenic mice for AD (3 xTgAD) and non-transgenic (NTg) control mice of the same ages were used. The chemotaxis, the anti-tumour activity of «natural killer» (NK) cells and the lymphoproliferative response in the presence of the mitogens concanavalin A and lipopolysaccharide, functions that decrease with age, were determined in splenic leucocytes. In addition, the differences in lifespan between 3 xTgAD and NTg were studied in parallel using other animals, until their death through natural causes.

Results

In 3 xTgAD, with respect to NTg, chemotaxis decreased at all ages studied, whereas in lymphoproliferative response this reduction was shown at 4 months and 9 months. NK activity was diminished only in young 3 xTgAD with respect to NTg. The 3 xTgAD showed a shorter lifespan than the NTg control group.

Conclusions

The 3 xTgAD mice show a premature immunosenescence, which could explain their early mortality. The determination of these immune functions at peripheral level could serve as a marker of the progression of the Alzheimer's disease.     

Selective Pressures on <Emphasis Type="Italic">Drosophila</Emphasis> Chemosensory Receptor Genes

The evolution and patterns of selection of genes encoding 10 Drosophila odorant receptors (Or) and the sex pheromone receptor Gr68a were investigated by comparing orthologous sequences across five to eight ecologically diverse species of Drosophila. Using maximum likelihood estimates of dN/dS ratios we show that all 11 genes sampled are under purifying selection, indicating functional constraint. Four of these genes (Or33c, Or42a, Or85e, and Gr68a) may be under positive selection, and if so, there is good evidence that 12 specific amino acid sites may be under positive selection. All of these sites are predicted to be located either in loop regions or just inside membrane spanning regions, and interestingly one of the two sites in Gr68a is in a similar position to a previously described polymorphism in Gr5a that causes a shift in sensitivity to its ligand trehalose. For three Ors, possible evidence for positive selection was detected along a lineage. These include Or22a in the lineage leading to D. mauritiana and Or22b in the lineage leading to D. simulans. This is of interest in light of previous data showing a change in ligand response profile for these species in the sensory neuron (ab3A) which expresses both Or22a and Or22b in D. melanogaster. In summary, while the main chemosensory function and/or structural integrity of these 10 Or genes and Gr68a are evolutionarily preserved, positive selection appears to be acting on some of these genes, at specific sites and along certain lineages, and provides testable hypotheses for further functional experimentation. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. [Reviewing Editor: Dr. David Pollock]     

Epigenetic drugs as pleiotropic agents in cancer treatment: biomolecular aspects and clinical applications

In the last three decades huge efforts have been made to characterize genetic defects responsible for cancer development and progression, leading to the comprehensive identification of distinct cellular pathways affected by the alteration of specific genes. Despite the undoubtable role of genetic mechanisms in triggering neoplastic cell transformation, epigenetic modifications (i.e., heritable changes of gene expression that do not derive from alterations of the nucleotide sequence of DNA) are rapidly emerging as frequent alterations that often occur in the early phases of tumorigenesis and that play an important role in tumor development and progression. Epigenetic alterations, such as modifications in DNA methylation patterns and post-translational modifications of histone tails, behave extremely different from genetic modifications, being readily revertable by "epigenetic drugs" such as inhibitors of DNA methyl transferases and inhibitors of histone deacetylases. Since epigenetic alterations in cancer cells affect virtually all cellular pathways that have been associated to tumorigenesis, it is not surprising that epigenetic drugs display pleiotropic activities, being able to concomitantly restore the defective expression of genes involved in cell cycle control, apoptosis, cell signaling, tumor cell invasion and metastasis, angiogenesis and immune recognition. Prompted by this emerging clinical relevance of epigenetic drugs, this review will focus on the large amount of available data, deriving both from in vitro experimentations and in vivo pre-clinical and clinical studies, which clearly indicate epigenetic drugs as effective modifiers of cancer phenotype and as positive regulators of tumor cell biology with a relevant therapeutic potential in cancer patients.     

Proteomic study of neuron and astrocyte cultures from senescence-accelerated mouse SAMP8 reveals degenerative changes

Senescence-accelerated prone (SAMP) strain 8 mice suffer an earlier development of cognitive age-related pathologies and a shorter life span than conventional mice. Protein alterations in astrocytes, in addition to those in neurons, may contribute to neurodegenerative damage. We applied proteomics techniques to study cell-specific early markers of brain aging-related degeneration in SAMP8. The two-dimensional protein expression patterns of the SAMP8 neuron and astrocyte cultures were compared with those obtained from senescence-accelerated resistant mouse strain 1 cultures. Differentially expressed spots were identified by matrix-assisted laser desorption/ionization–time of flight peptide map fingerprinting and database search. Proteins belonged to cell pathways of energy metabolism, biosynthesis, cell transduction and signaling, stress response, and the maintenance of cytoskeletal functions. Most of the changes were cell type specific. However, there was a general increase in cell transduction, signaling, and stress-related proteins and a decrease in cytoskeletal proteins. In addition, neurons showed an increased expression of proteins involved in biosynthetic pathways. A number of the protein alterations have been previously reported in the brain tissue proteome of SAMP8, aged brain or Alzheimer's disease brain. Alterations in neuron and astrocyte proteoma indicated that both cell types are involved in the brain degenerative changes of SAMP8 mice. However, network analysis suggests that neuronal changes are more complex and have a greater influence.     

The Yeast INO80 Complex Operates as a Tunable DNA Length-Sensitive Switch to Regulate Nucleosome Sliding

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Measurement of nephrolithiasis urinary markers by capillary electrophoresis

A previously developed method for screening organic acidurias by capillary electrophoresis has been validated for oxalate and citrate measurement in urine. Sample pretreatment is minimum, just acidification and centrifugation. Detection is by direct UV. Validation parameters of the method can be considered adequate. Response is linear for both analytes in standards and samples. The assayed ranges were 200–1000 mg/l for citrate and 10–200 mg/l for oxalate. Recoveries ranged from 99.4±3 to 101.7±2.4%, maximum imprecision in oxalate concentration was of 7.6% RSD and limits of detection in samples were 0.67 mg/l for oxalate and 25.9 mg/l for citrate, both lower than the measured values in samples. Identification of increased glyoxylic (oxoacetic acid) and glyceric acids (2,3-dihydroxy propanoic) are also included to facilitate the diagnosis.     

Disparate views of community in primary health care: understanding how perceptions influence success

The importance of community in primary health care (PHC) is evident in the role of community participation and in the types of programs that are routinely implemented (community health-worker [CHW] programs, community clinics, community-based disease-control programs). Few health care providers and program administrators, however, have considered the meaning of community. Instead, they frequently impose their own definition of community and assume that it corresponds to local realities. This is problematic because target populations may have different ideas about what a community is and how it functions. When disparate ideas of community exist, they can affect the implementation of PHC programs, leading to low rates of acceptance, participation, and utilization. Using two examples, a community clinic in El Alto, Bolivia, and a CHW program in Rio Branco, Brazil, this article discusses some of the problems that arise when local definitions of community do not correspond to programmatic definitions.     

Coexpression of two functional odor receptors in one neuron

One of the most fundamental tenets in the field of olfaction is that each olfactory receptor neuron (ORN) expresses a single odorant receptor. However, the one receptor-one neuron principle is difficult to establish rigorously. Here we construct a receptor-to-neuron map for an entire olfactory organ in Drosophila and find that two receptor genes are coexpressed in one class of ORN. Both receptors are functional in an in vivo expression system, they are only 16% identical in amino acid sequence, and the genes that encode them are unlinked. Most importantly, their coexpression has been conserved for >45 million years. Expression of multiple odor receptors in a cell provides an additional degree of freedom for odor coding.     

Selective actions of growth hormone on rat liver estrogen binding proteins

Levels of hepatic estrogen receptor were 9.0 ± 2.4 fmoles/mg cytosol protein in intact females compared to 3.4 ± 2.2 in hypophysectomized females. Likewise, levels of receptor were 9.8 ± 1.5 fmoles/mg cytosol protein in intact males and 2.7 ± 1.8 in hypophysectomized males. Hypophysectomy abolished the sex differences in a second class of binding sites termed higher capacity lower affinity binding sites by increasing female levels and decreasing male levels. Treatment of hypophysectomized male or female rats with growth hormone (2 units/kg body wt, two times daily) restored normal levels of hepatic estrogen receptor. Administration of growth hormone to hypophysectomized rats did not reverse the effects of hypophysectomy on higher capacity lower affinity binding sites. These studies demonstrate that growth hormone exerts selective actions on different forms of hepatic estrogen binding proteins.     

MEASURING RATES OF AMMONIUM ASSIMILATION IN MARINE ALGAE: USE OF THE PROTONOPHORE CARBONYL CYANIDE m-CHLOROPHENYLHYDRAZONE TO DISTINGUISH BETWEEN UPTAKE AND ASSIMILATION

A method for determining rates of ammonium assimilation in marine algae is described. Ammonium assimilation is defined as the decrease in total (medium + cellular) ammonium. The protonophore carbonyl cyanide m- chlorophenylhydrazone (CCCP) was used to distinguish between uptake and assimilation of ammonium. Ammonium uptake by nitrogen-replete and nitrogen-starved cells of the diatom Phaeodactylum tricornutum Bohlin and the green macroalga Enteromorpha sp. was completely (98%–99%) inhibited in the presence of 100 μM CCCP. In addition to inhibiting further uptake of ammonium, CCCP promoted the release of unassimilated ammonium by nitrogen-replete and nitrogen-starved P. tricornutum and Enteromorpha that had been allowed to take up ammonium for a period. Most (97.5%) of preaccumulated ¹⁴C-methylammonium was released by nitrogen-starved P. tricornutum in the presence of CCCP. Specific rates of ammonium assimilation in nitrogen-replete cultures of P. tricornutum were identical to the maximum growth rate, but specific rates in nitrogen-starved cultures were fourfold greater. Rates of ammonium assimilation in Enteromorpha during both the surge and the internally controlled uptake phases were the same as the internally controlled rate of uptake, suggesting that the latter is a reliable measure of the maximum rate of assimilation.