Astrocyte Resilience to Oxidative Stress Induced by Insulin-like Growth Factor I (IGF-I) Involves Preserved AKT (Protein Kinase B) Activity

Disruption of insulin-like growth factor I (IGF-I) signaling is a key step in the development of cancer or neurodegeneration. For example, interference of the prosurvival IGF-I/AKT/FOXO3 pathway by redox activation of the stress kinases p38 and JNK is instrumental in neuronal death by oxidative stress. However, in astrocytes, IGF-I retains its protective action against oxidative stress. The molecular mechanisms underlying this cell-specific protection remain obscure but may be relevant to unveil new ways to combat IGF-I/insulin resistance. Here, we describe that, in astrocytes exposed to oxidative stress by hydrogen peroxide (H₂O₂), p38 activation did not inhibit AKT (protein kinase B) activation by IGF-I, which is in contrast to our previous observations in neurons. Rather, stimulation of AKT by IGF-I was significantly higher and more sustained in astrocytes than in neurons either under normal or oxidative conditions. This may be explained by phosphorylation of the phosphatase PTEN at the plasma membrane in response to IGF-I, inducing its cytosolic translocation and preserving in this way AKT activity. Stimulation of AKT by IGF-I, mimicked also by a constitutively active AKT mutant, reduced oxidative stress levels and cell death in H₂O₂-exposed astrocytes, boosting their neuroprotective action in co-cultured neurons. These results indicate that armoring of AKT activation by IGF-I is crucial to preserve its cytoprotective effect in astrocytes and may form part of the brain defense mechanism against oxidative stress injury.     

Genomic Characterization of Phenylalanine Ammonia Lyase Gene in Buckwheat

Phenylalanine Ammonia Lyase (PAL) gene which plays a key role in bio-synthesis of medicinally important compounds, Rutin/quercetin was sequence characterized for its efficient genomics application. These compounds possessing anti-diabetic and anti-cancer properties and are predominantly produced by Fagopyrum spp. In the present study, PAL gene was sequenced from three Fagopyrum spp. (F. tataricum, F. esculentum and F. dibotrys) and showed the presence of three SNPs and four insertion/deletions at intra and inter specific level. Among them, the potential SNP (position 949^th bp G>C) with Parsimony Informative Site was selected and successfully utilised to individuate the zygosity/allelic variation of 16 F. tataricum varieties. Insertion mutations were identified in coding region, which resulted the change of a stretch of 39 amino acids on the putative protein. Our Study revealed that autogamous species (F. tataricum) has lower frequency of observed SNPs as compared to allogamous species (F. dibotrys and F. esculentum). The identified SNPs in F. tataricum didn’t result to amino acid change, while in other two species it caused both conservative and non-conservative variations. Consistent pattern of SNPs across the species revealed their phylogenetic importance. We found two groups of F. tataricum and one of them was closely related with F. dibotrys. Sequence characterization information of PAL gene reported in present investigation can be utilized in genetic improvement of buckwheat in reference to its medicinal value.     

Bone Cell-autonomous Contribution of Type 2 Cannabinoid Receptor to Breast Cancer-induced Osteolysis

The cannabinoid type 2 receptor (CB2) has previously been implicated as a regulator of tumor growth, bone remodeling, and bone pain. However, very little is known about the role of the skeletal CB2 receptor in the regulation of osteoblasts and osteoclasts changes associated with breast cancer. Here we found that the CB2-selective agonists HU308 and JWH133 reduced the viability of a variety of parental and bone-tropic human and mouse breast cancer cells at high micromolar concentrations. Under conditions in which these ligands are used at the nanomolar range, HU308 and JWH133 enhanced human and mouse breast cancer cell-induced osteoclastogenesis and exacerbated osteolysis, and these effects were attenuated in cultures obtained from CB2-deficient mice or in the presence of a CB2 receptor blocker. HU308 and JWH133 had no effects on osteoblast growth or differentiation in the presence of conditioned medium from breast cancer cells, but under these circumstances both agents enhanced parathyroid hormone-induced osteoblast differentiation and the ability to support osteoclast formation. Mechanistic studies in osteoclast precursors and osteoblasts showed that JWH133 and HU308 induced PI3K/AKT activity in a CB2-dependent manner, and these effects were enhanced in the presence of osteolytic and osteoblastic factors such as RANKL (receptor activator of NFκB ligand) and parathyroid hormone. When combined with published work, these findings suggest that breast cancer and bone cells exhibit differential responses to treatment with CB2 ligands depending upon cell type and concentration used. We, therefore, conclude that both CB2-selective activation and antagonism have potential efficacy in cancer-associated bone disease, but further studies are warranted and ongoing.     

Seasonal transmission of Leishmania (Leishmania) mexicana in the state of Campeche, Yucatan Peninsula, Mexico

In the Yucatan Peninsula, Mexico, localized cutaneous leishmaniasis (LCL) caused by Leishmania (Leishmania) mexicana is a typical wild zoonosis restricted to the forest, and humans are only accidentally involved. The transmission of L. (L.) mexicana has been related to the patient's occupation: "chicleros" (gum collectors) and agricultural workers. The objective of this study was to document L. (L.) mexicana seasonally of transmission in endemic areas of LCL in the state of Campeche, Yucatan Peninsula, Mexico. The timing of incidence of LCL in humans during 1993-1994, as well as the rate and time of infection in rodents and sand flies between February 1993 and March 1995 were analyzed. Rodents and sand flies were found infected between November and March, when men carried out their field activities and are exposed. Based on results analyzed, it is concluded that L. (L.) mexicana in the endemic area of LCL in the state of Campeche, Yucatan Peninsula, Mexico, presents a seasonal transmission restricted to the months of November to March. The knowledge of the timing of the transmission cycle in an endemic area of leishmaniasis is very important because intervention measures on the high-risk focus and population might be restricted.     

Conformational plasticity of the Gerstmann-Sträussler-Scheinker disease peptide as indicated by its multiple aggregation pathways

The existence of several prion strains and their capacity of overcoming species barriers seem to point to a high conformational adaptability of the prion protein. To investigate this structural plasticity, we studied here the aggregation pathways of the human prion peptide PrP82-146, a major component of the Gerstmann-Sträussler-Scheinker amyloid disease.By Fourier transform infrared (FT-IR) spectroscopy, electron microscopy, and atomic force microscopy (AFM), we monitored the time course of PrP82-146 fibril formation. After incubation at 37 °C, the unfolded peptide was found to aggregate into oligomers characterized by intermolecular β-sheet infrared bands. At a critical oligomer concentration, the emergence of a new FT-IR band allowed to detect fibril formation. A different intermolecular β-sheet interaction of the peptides in oligomers and in fibrils is, therefore, detected by FT-IR spectroscopy, which, in addition, suggests a parallel orientation of the cross β-sheet structures of PrP82-146 fibrils. By AFM, a wide distribution of PrP82-146 oligomer volumes—the smallest ones containing from 5 to 30 peptides—was observed. Interestingly, the statistical analysis of AFM data enabled us to detect a quantization in the oligomer height values differing by steps of ∼ 0.5 nm that could reflect an orientation of oligomer β-strands parallel with the sample surface. Different morphologies were also detected for fibrils that displayed high heterogeneity in their twisting periodicity and a complex hierarchical assembly.Thermal aggregation of PrP82-146 was also investigated by FT-IR spectroscopy, which indicated for these aggregates an intermolecular β-sheet interaction different from that observed for oligomers and fibrils. Unexpectedly, random aggregates, induced by solvent evaporation, were found to display a significant α-helical structure as well as several β-sheet components.All these results clearly point to a high plasticity of the PrP82-146 peptide, which was found to be capable of undergoing several aggregation pathways, with end products displaying different secondary structures and intermolecular interactions.     

Medium chain fatty acids in intrauterine growth restricted and small for gestational age pregnancies

Introduction

Low birth weight is associated with an increased risk of heart disease, high blood pressure and diabetes in adult life. Fetal growth is determined by nutrient availability, which is related to placenta nutrient transport. Medium chain fatty acids (MCFAs) are a particular class of nutrients, known to be a readily available energy source. Until now no data are reported on these MCFAs in low birth weight fetus.

Aim

This is a prospective study conducted in a tertiary center of prenatal diagnosis to investigate the maternal and fetal MCFAs levels in appropriate for gestational age (AGA), intrauterine growth restricted (IUGR), and small for gestational age (SGA) pregnancies.

Method

The plasmatic levels of MCFAs in AGA, IUGR and SGA mother–infant pairs were quantified by gas chromatography–mass spectrometry. The analytical method had a linearity range of 0.1–50 mg/L and a limit of quantification of 0.03 mg/L. Reduced fetal growth was defined as an estimated fetal weight below the 3rd–10th percentile for gestational age, with (IUGR) or without (SGA) fetal Doppler abnormalities.

Result

Maternal and fetal MCFAs plasma levels were significantly different among SGA, IUGR and AGA groups. Additionally, the observed MCFAs fetal to maternal ratio is >1 for IUGR group, whilst for SGA and AGA the fetal to maternal ratio is less than one.

Conclusion

Changes in MCFAs levels in fetal and maternal plasma are not related to placental functionality or nutrients availability, suggesting the presence of a de novo biosynthesis.

     

Chitosan induces different L-arginine metabolic pathways in resting and inflammatory macrophages

Chitosan is a linear polymer of N-acetyl-D-glucosamine and deacetylated glucosamine widely used as a wound-healing accelerator in clinical and veterinary medicine. Chitosan enhances the functions of inflammatory cells such as macrophages (Mphi), inducing the production of cytokines as well as the expression of activation markers, Fc receptors and mannose receptor. In this work we studied the effects of chitosan on the arginine metabolic pathways of both resident and inflammatory (proteose-peptone elicited) rat Mphi. Our results show that low molecular weight (LMW) chitosan activated moderately both the inducible nitric oxide synthase (iNOS) and arginase pathways in resident Mphi. In inflammatory Mphi treated with chitosan instead, the arginase activity was strongly enhanced. Supernatants of chitosan-stimulated Mphi enhanced the proliferation of the rat cell line C6. These findings suggest that the healing activity of chitosan could rely on the enhanced arginase activity observed in a wound-associated inflammatory milieu.     

Environmentally Dependent Morphological Variability in Seven Apomictic Microspecies from Alchemilla L. (Rosaceae)

Apomictic microspecies, for example those of the genus Alchemilla, are often difficult to distinguish. Still, their differences are thought to be persistent due to apomixis. Apomicts are argued to have general-purpose genotypes. The present study aims to assess the variation of morphological characters of Alchemilla depending on environmental conditions both in nature and experimentally; to evaluate the efficacy of characters for identifying the different microspecies; to assess the similarity of different microspecies; and to determine if Alchemilla microspecies have general-purpose genotypes that are not dependent on environmental conditions. The variability of selected characters in seven microspecies of Alchemilla was studied in nature and five microspecies were grown in a common garden experiment. The growing conditions of the latter were subjected to various manipulations (fertilization, shading and irrigation). Typical natural habitats of Alchemilla exhibited only small differences. Environmental conditions therefore had little effect on morphological characters. Neither cultivation in the common garden nor manipulation of conditions therein had a significant impact on the discrimination of microspecies. However, the metric characters were larger in the garden relative to those observed in nature, particularly under fertilization. Fertilization affected most characters, whereas shading and irrigation did not. The most effective characters for discriminating between microspecies were the ratios of the metric characters. Two species pairs: A. vulgaris and A. micans, as well as A. glaucescens and A. hirsuticaulis were morphologically close; however, the species within these pairs could still be distinguished. The morphological characters of Alchemilla microspecies were only slightly dependent on the environmental conditions.     

A malaria parasite-encoded vacuolar H(+)-ATPase is targeted to the host erythrocyte

The asexual development of malaria parasites inside the erythrocyte is accompanied by changes in the composition, structure, and function of the host cell membrane and cytoplasm. The parasite exports a membrane network into the host cytoplasm and several proteins that are inserted into the erythrocyte membrane, although none of these proteins has been shown to have enzymatic activity. We report here that a functional malaria parasite-encoded vacuolar (V)-H(+)-ATPase is exported to the erythrocyte and localized in membranous structures and in the plasma membrane of the infected erythrocyte. This localization was determined by separation of parasite and erythrocyte membranes and determination of enzyme marker activities and by immunofluorescence microscopy assays using antibodies against the B subunit of the malarial V-H(+)-ATPase and erythrocyte (spectrins) and parasite (merozoite surface protein 1) markers. Our results suggest that this pump has a role in the maintenance of the intracellular pH (pH(i)) of the infected erythrocyte. Our results also indicate that although the pH(i) maintained by the V-H(+)-ATPase is important for maximum uptake of small metabolites at equilibrium, it does not appear to affect transport across the erythrocyte membrane and is, therefore, not involved in the previously described phenomenon of increased permeability of infected erythrocytes that is sensitive to chloride channel inhibitors (new permeation pathway). This constitutes the first report of the presence of a functional enzyme of parasite origin in the plasma membrane of its host.