Exercise training provides cardioprotection via a reduction in reactive oxygen species in rats submitted to myocardial infarction induced by isoproterenol

Exercise training has demonstrated cardioprotection effects. However, the exact mechanism behind this effect is not is clear. The present study evaluated the effects of 12 weeks of previous treadmill training on the levels of oxidative damage, antioxidant enzyme activity and injury in the myocardium of rats submitted to infarction induced by isoproterenol (ISO). Isoproterenol treatment (80 mg/kg given over 2 days in two equal doses) caused arrhythmias and 60% mortality within 24 h of the last injection in the control group (C + ISO) group when compared with the saline control group (saline). Creatine Kinase ? MB levels were markedly increased in hearts from ISO-treated animals in the C + ISO group. Twelve weeks of treadmill training reduced superoxide production, lipid peroxidation levels and protein carbonylation in these animals, as well as increasing the activities and expressions of SOD and CAT. Previous training also reduced CK-MB levels and numbers of deaths by 40%, preventing the deleterious effects of ISO. Based on the data obtained in this study, it is suggested that 12-week treadmill training increases antioxidant enzymes, decreases oxidative damage and reduces the degree of infarction induced by ISO in the hearts of male rats.     

Rice bran enzymatic extract restores endothelial function and vascular contractility in obese rats by reducing vascular inflammation and oxidative stress

BackgroundRice bran enzymatic extract (RBEE) used in this study has shown beneficial activities against dyslipidemia, hyperinsulinemia and hypertension. Our aim was to investigate the effects of a diet supplemented with RBEE in vascular impairment developed in obese Zucker rats and to evaluate the main mechanisms mediating this action.Methods and resultsObese Zucker rats were fed a 1% and 5% RBEE-supplemented diet (O1% and O5%). Obese and their lean littermates fed a standard diet were used as controls (OC and LC, respectively). Vascular function was evaluated in aortic rings in organ baths. The role of nitric oxide (NO) was investigated by using NO synthase (NOS) inhibitors. Aortic expression of endothelial NOS (eNOS), inducible NOS (iNOS), tumor necrosis factor (TNF)-α and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits and superoxide production in arterial wall were determined. Endothelial dysfunction and vascular hyperreactivity to phenylephrine in obese rats were ameliorated by RBEE treatment, particularly with 1% RBEE. Up-regulation of eNOS protein expression in RBEE-treated aortas should contribute to this activity. RBEE attenuated vascular inflammation by reducing aortic iNOS and TNF-α expression. Aortas from RBEE-treated groups showed a significant decrease of superoxide production and down-regulation of NADPH oxidase subunits.ConclusionRBEE treatment restored endothelial function and vascular contractility in obese Zucker rats through a reduction of vascular inflammation and oxidative stress. These results show the nutraceutical potential of RBEE to prevent obesity-related vascular complications.     

Above and beyond state-of-the-art approaches to investigate sequence data: summary of methods and results from the population-based association group at the Genetic Analysis Workshop 19

This paper summarizes the contributions from the Population-Based Association group at the Genetic Analysis Workshop 19. It provides an overview of the new statistical approaches tried out by group members in order to take best advantage of population-based sequence data.Although contributions were highly heterogeneous regarding the applied quality control criteria and the number of investigated variants, several technical issues were identified, leading to practical recommendations. Preliminary analyses revealed that Hurdle-negative binomial regression is a promising approach to investigate the distribution of allele counts instead of called genotypes from sequence data. Convergence problems, however, limited the use of this approach, creating a technical challenge shared by environment-stratified models used to investigate rare variant-environment interactions, as well as by rare variant haplotype analyses using well-established public software. Estimates of relatedness and population structure strongly depended on the allele frequency of selected variants for inference. Another practical recommendation was that dissenting probability values from standard and small-sample tests of a particular hypothesis may reflect a lack of validity of large-sample approximations. Novel statistical approaches that integrate evolutionary information showed some advantage to detect weak genetic signals, and Bayesian adjustment for confounding was able to efficiently estimate causal genetic effects. Haplotype association methods may constitute a valuable complement of collapsing approaches for sequence data. This paper reports on the experience of members of the Population-Based Association group with several novel, promising approaches to preprocessing and analyzing sequence data, and to following up identified association signals.     

E‐cadherin expression is associated with somatostatin analogue response in acromegaly

Acromegaly is a rare disease resulting from hypersecretion of growth hormone (GH) and insulin‐like growth factor 1 (IGF1) typically caused by pituitary adenomas, which is associated with increased mortality and morbidity. Somatostatin analogues (SSAs) represent the primary medical therapy for acromegaly and are currently used as first‐line treatment or as second‐line therapy after unsuccessful pituitary surgery. However, a considerable proportion of patients do not adequately respond to SSAs treatment, and therefore, there is an urgent need to identify biomarkers predictors of response to SSAs. The aim of this study was to examine E‐cadherin expression by immunohistochemistry in fifty‐five GH‐producing pituitary tumours and determine the potential association with response to SSAs as well as other clinical and histopathological features. Acromegaly patients with tumours expressing low E‐cadherin levels exhibit a worse response to SSAs. E‐cadherin levels are associated with GH‐producing tumour histological subtypes. Our results indicate that the immunohistochemical detection of E‐cadherin might be useful in categorizing acromegaly patients based on the response to SSAs.     

4-Deoxyraputindole C induces cell death and cell cycle arrest in tumor cell lines

Several molecules extracted from natural products exhibit different biological activities, such as ion channel modulation, activation of signaling pathways, and anti-inflammatory or antitumor activity. In this study, we tested the antitumor ability of natural compounds extracted from the Raputia praetermissa plant. Among the compounds tested, an alkaloid, here called compound S4 (4-Deoxyraputindole C), showed antitumor effects against human tumor lineages. Compound S4 was the most active against Raji, a lymphoma lineage, promoting cell death with characteristics that including membrane permeabilization, dissipation of the mitochondrial potential, increased superoxide production, and lysosomal membrane permeabilization. The use of cell death inhibitors such as Z-VAD-FMK (caspase inhibitor), necrostatin-1 (receptor-interacting serine/threonine-protein kinase 1 inhibitor), E-64 (cysteine peptidases inhibitor), and N-acetyl- L -cysteine (antioxidant) did not decrease compound S4-dependent cell death. Additionally, we tested the effect of cellular activity on adherent human tumor cells. The highest reduction of cellular activity was observed in A549 cells, a lung carcinoma lineage. In this lineage, the effect on the reduction of the cellular activity was due to cell cycle arrest, without plasma membrane permeabilization, loss of the mitochondrial potential or lysosomal membrane permeabilization. Compound S4 was able to inhibit cathepsin B and L by a nonlinear competitive (negative co-operativity) and simple-linear competitive inhibitions, respectively. The potency of inhibition was higher against cathepsin L. Compound S4 promoted cell cycle arrest at G ₀ and G ₂ phase, and increase the expression of p16 and p21 proteins. In conclusion, compound S4 is an interesting molecule against cancer, promoting cell death in the human lymphoma lineage Raji and cell cycle arrest in the human lung carcinoma lineage A549.     

Stability in a metapopulation model with density-dependent dispersal

A spatially explicit metapopulation model with positive density-dependent migration is analysed. We obtained conditions under which a previously stable system can be driven to instability caused by a density-dependent migration mechanism. The stability boundary depends on the rate of increase of the number of migrants on each site at local equilibrium, on the intrinsic rate of increase at local level, on the number of patches, and on topological aspects regarding the connectivity between patches. A concrete example is presented illustrating the dynamics on the dispersal-induced unstable regime.     

Epoxy sepabeads: a novel epoxy support for stabilization of industrial enzymes via very intense multipoint covalent attachment

Sepabeads-EP (a new epoxy support) has been utilized to immobilize-stabilize the enzyme penicillin G acylase (PGA) via multipoint covalent attachment. These supports are very robust and suitable for industrial purposes. Also, the internal geometry of the support is composed by cylindrical pores surrounded by the convex surfaces (this offers a good geometrical congruence for reaction with the enzyme), and it has a very high superficial density of epoxy groups (around 100 micromol/mL). These features should permit a very intense enzyme-support interaction. However, the final stability of the immobilized enzyme is strictly dependent on the immobilization protocol. By using conventional immobilization protocols (neutral pH values, nonblockage of the support) the stability of the immobilized enzyme was quite similar to that achieved using Eupergit C to immobilize the PGA. However, when using a more sophisticated three-step immobilization/stabilization/blockage procedure, the Sepabeads derivative was hundreds-fold more stable than Eupergit C derivatives. The protocol used was as follows: (i) the enzyme was first covalently immobilized under very mild experimental conditions (e.g., pH 7.0 and 20 degrees C); (ii) the already immobilized enzyme was further incubated under more drastic conditions (higher pH values, long incubation periods, etc.) in order to "facilitate" the formation of new covalent linkages between the immobilized enzyme molecule and the support; (iii) the remaining epoxy groups of the support were blocked with very hydrophilic compounds to stop any additional interaction between the enzyme and the support. This third point was found to be critical for obtaining very stable enzymes: derivatives blocked with mercaptoethanol were much less stable than derivatives blocked with glycine or other amino acids. This was attributed to the better masking of the hydrophobicity of the support by the amino acids (having two charges).     

Artificial endosperm of Cleopatra tangerine zygotic embryos: a model for somatic embryo encapsulation

Synthetic seed technology may be of value in breeding programs and allow the propagation of many elite genotype-derived plants in a short time. In this work, a range of artificial endosperm treatments of Cleopatra tangerine zygotic embryos were evaluated for suitability for encapsulation of somatic embryos. Different complexing ions in the form of alginate capsules, zeolite as an ion exchanger and the relationship between capsule-nutrient gel on germination of zygotic embryos, were evaluated. Artificial endosperm assays showed that abscisic acid (1 μM) and mannitol (0.25 M) delayed germination and conversion of zygotic embryos, whereas amino acid supplements (proline, glutamic acid and arginine) accelerated the conversion process. An artificial endosperm was used to encapsulate somatic and zygotic embryos. After encapsulation, zygotic embryos germinated after four days of culture while somatic embryos germinated asynchronously after 20 days. Somatic embryo-derived plantlets showed greater vigour than zygotic embryo-derived plantlets. Results showed that this artificial endosperm is adequate for Cleopatra tangerine somatic embryo germination and conversion into plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

Changes in DNA Content and Cellular Death during a Starvation-Survival Process of Escherichia coli in River Water

Abstract Four nucleoid staining procedures were compared during the starvation-survival process of Escherichia coli in river water. Only the method performed as a modification of the standard acridine orange direct procedure allowed us to visualize nucleoids during the 95 days of experimentation. Moreover, with this method the total number of cells and nucleoid-containing cells can be simultaneously enumerated. The decrease of the chromosomal DNA content of population and of the nucleoid-containing cells indicates that ghosts form and cellular death occurs throughout the starvation-survival process. A long time (<30 days) is needed for non-nucleoid-containing cells to appear in river water; plasmid DNA is also negatively affected by environmental stress. After 4 days of storage in river water, the need to increase the volume of lysed cells used for the plasmid band visualization as well as the decrease in the plasmid band intensity would indicate a decrease in the plasmid DNA content during the starvation-survival process. According to our results, both chromosomal and plasmid DNA content decrease during the starvation-survival process of E. coli in river water. Received: 13 May 1998; Accepted: 14 September 1998