Induction of through-thickness compressive residual stress fields in thin Al2024-T351 plates by laser shock processing

Laser Shock Processing (LSP) has been demonstrated as an emerging technique for the induction of RS’s fields in subsurface layers of relatively thick specimens. However, the LSP treatment of relatively thin specimens brings, as an additional consequence, the possible bending in a process of laser shock forming. This effect poses a new class of problems regarding the attainment of specified RS’s depth profiles in the mentioned type of sheets, and, what can be more critical, an overall deformation of the treated component. The analysis of the problem of LSP treatment for induction of tentatively through-thickness RS’s fields for fatigue life enhancement in relatively thin sheets in a way compatible with reduced overall workpiece deformation due to spring-back self-equilibration is envisaged in this paper. The coupled theoretical-experimental predictive approach developed by the authors has been applied to the specification of LSP treatments for achievement of RS's fields tentatively able to retard crack propagation on normalized specimens. A convergence between numerical code results and experimental results coming from direct RS's measurement is presented as a first step for the treatment of the normalized specimens under optimized conditions and verification of the crack retardation properties virtually induced.

QUALIDADE DE VIDA E STRESS DE CRIANÇAS E ADOLESCENTES COM CÂNCER EM ESTÁGIO DE REMISSÃO E RECIDIVA

O câncer em crianças até cerca de duas décadas, era considerado uma doença crônica, com prognóstico desfavorável, resultando na maioria dos casos, em morte. Atualmente, tem-se apresentado como uma doença com melhores perspectivas, onde 70% das crianças acometidas por essa doença podem ser curadas, quando diagnosticadas precocemente, e tratadas em centros especializados¹. Este estudo teve como objetivo, avaliar a qualidade de vida e o stress de crianças e adolescentes com câncer, em remissão e recidiva. Trata-se de um estudo correlacional, quali-quantitativo, transversal. Foi desenvolvido no ambulatório de oncologia pediátrica da Faculdade de Medicina do ABC, e na enfermaria do Hospital Mário Covas. Contou com a colaboração de 40 sujeitos, com idades entre 06 a 14 anos, de ambos os sexos. Como instrumento para medir a qualidade de vida, foi utilizado o Child Health Questionnaire (CHQ-PF50), que possui 15 conceitos em saúde, abrangendo aspectos físicos e psicossociais e para medir o stress, a Escala de Stress Infantil (ESI), que tem como objetivo, avaliar o stress da criança, através de reações físicas e psicológicas. Os resultados indicaram que no domínio físico (PhS), as crianças em situação clínica de recidiva e remissão não apresentam diferenças significativas em relação às variáveis: qualidade de vida e stress, porém, no domínio psicossocial (PsS), houve diferença estatisticamente significante, indicando que os meninos apresentam melhor qualidade de vida e menor stress, se comparados com as meninas, mostrando que o emocional interfere nesse resultado.(AU)

QUALIDADE DE VIDA E STRESS DE CRIANÇAS E ADOLESCENTES COM CÂNCER EM ESTÁGIO DE REMISSÃO E RECIDIVA

O câncer em crianças até cerca de duas décadas, era considerado uma doença crônica, com prognóstico desfavorável, resultando na maioria dos casos, em morte. Atualmente, tem-se apresentado como uma doença com melhores perspectivas, onde 70% das crianças acometidas por essa doença podem ser curadas, quando diagnosticadas precocemente, e tratadas em centros especializados¹. Este estudo teve como objetivo, avaliar a qualidade de vida e o stress de crianças e adolescentes com câncer, em remissão e recidiva. Trata-se de um estudo correlacional, quali-quantitativo, transversal. Foi desenvolvido no ambulatório de oncologia pediátrica da Faculdade de Medicina do ABC, e na enfermaria do Hospital Mário Covas. Contou com a colaboração de 40 sujeitos, com idades entre 06 a 14 anos, de ambos os sexos. Como instrumento para medir a qualidade de vida, foi utilizado o Child Health Questionnaire (CHQ-PF50), que possui 15 conceitos em saúde, abrangendo aspectos físicos e psicossociais e para medir o stress, a Escala de Stress Infantil (ESI), que tem como objetivo, avaliar o stress da criança, através de reações físicas e psicológicas. Os resultados indicaram que no domínio físico (PhS), as crianças em situação clínica de recidiva e remissão não apresentam diferenças significativas em relação às variáveis: qualidade de vida e stress, porém, no domínio psicossocial (PsS), houve diferença estatisticamente significante, indicando que os meninos apresentam melhor qualidade de vida e menor stress, se comparados com as meninas, mostrando que o emocional interfere nesse resultado.(AU)

Early-life exposure to endotoxin alters hypothalamic–pituitary–adrenal function and predisposition to inflammation

We have investigated whether exposure to Gram-negative bacterial endotoxin in early neonatal life can alter neuroendocrine and immune regulation in adult animals. Exposure of neonatal rats to a low dose of endotoxin resulted in long-term changes in hypothalamic–pituitary–adrenal (HPA) axis activity, with elevated mean plasma corticosterone concentrations that resulted from increased corticosterone pulse frequency and pulse amplitude. In addition to this marked effect on the development of the HPA axis, neonatal endotoxin exposure had long-lasting effects on immune regulation, including increased sensitivity of lymphocytes to stress-induced suppression of proliferation and a remarkable protection from adjuvant-induced arthritis. These findings demonstrate a potent and long-term effect of neonatal exposure to inflammatory stimuli that can program major changes in the development of both neuroendocrine and immunological regulatory mechanisms.

Prenatal stress produces learning deficits associated with an inhibition of neurogenesis in the hippocampus

Early experiences such as prenatal stress significantly influence the development of the brain and the organization of behavior. In particular, prenatal stress impairs memory processes but the mechanism for this effect is not known. Hippocampal granule neurons are generated throughout life and are involved in hippocampal-dependent learning. Here, we report that prenatal stress in rats induced lifespan reduction of neurogenesis in the dentate gyrus and produced impairment in hippocampal-related spatial tasks. Prenatal stress blocked the increase of learning-induced neurogenesis. These data strengthen pathophysiological hypotheses that propose an early neurodevelopmental origin for psychopathological vulnerabilities in aging.

Increased mitochondrial oxidative stress in the Sod2 (+/−) mouse results in the age-related decline of mitochondrial function culminating in increased apoptosis

To determine the importance of mitochondrial reactive oxygen species toxicity in aging and senescence, we analyzed changes in mitochondrial function with age in mice with partial or complete deficiencies in the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD). Liver mitochondria from homozygous mutant mice, with a complete deficiency in MnSOD, exhibited substantial respiration inhibition and marked sensitization of the mitochondrial permeability transition pore. Mitochondria from heterozygous mice, with a partial deficiency in MnSOD, showed evidence of increased proton leak, inhibition of respiration, and early and rapid accumulation of mitochondrial oxidative damage. Furthermore, chronic oxidative stress in the heterozygous mice resulted in an increased sensitization of the mitochondrial permeability transition pore and the premature induction of apoptosis, which presumably eliminates the cells with damaged mitochondria. Mice with normal MnSOD levels show the same age-related mitochondrial decline as the heterozygotes but occurring later in life. The premature decline in mitochondrial function in the heterozygote was associated with the compensatory up-regulation of oxidative phosphorylation enzyme activity. Thus mitochondrial reactive oxygen species production, oxidative stress, functional decline, and the initiation of apoptosis appear to be central components of the aging process.

Altered ubiquitination and stability of aquaporin-1 in hypertonic stress

Aquaporin-1 (AQP1) water channel protein expression is increased by hypertonic stress. The contribution of changes in protein stability to hypertonic induction of AQP1 have not been described. Incubation of BALB/c fibroblasts spontaneously expressing AQP1 with proteasome inhibitors increased AQP1 expression, suggesting basal proteasome-dependent degradation of the protein. Degradation by the proteasome is thought to be triggered by polyubiquitination of a target protein. To determine whether AQP1 is ubiquitinated, immunoprecipitation with anti-AQP1 antibodies was performed, and the resultant samples were probed by protein immunoblot for the presence of ubiquitin. Immunoblots demonstrated ubiquitination of AQP1 under control conditions that increased after treatment with proteasome inhibitors (MG132, lactacystin). Exposure of cells to hypertonic medium for as little as 4 h decreased ubiquitination of AQP1, an effect that persisted through 24 h in hypertonic medium. Using metabolic labeling with [35S]methionine, the half-life of AQP1 protein under isotonic conditions was found to be <4 h. AQP1 protein half-life was markedly increased by exposure of cells to hypertonic medium. These observations provide evidence that aquaporins are a target for ubiquitination and proteasome-dependent degradation. Additionally, these studies demonstrate that reduced protein ubiquitination and increased protein stability lead to increased levels of AQP1 expression during hypertonic stress.

Evolution of genome–phenome diversity under environmental stress

The genomic era revolutionized evolutionary biology. The enigma of genotypic-phenotypic diversity and biodiversity evolution of genes, genomes, phenomes, and biomes, reviewed here, was central in the research program of the Institute of Evolution, University of Haifa, since 1975. We explored the following questions. (i) How much of the genomic and phenomic diversity in nature is adaptive and processed by natural selection? (ii) What is the origin and evolution of adaptation and speciation processes under spatiotemporal variables and stressful macrogeographic and microgeographic environments? We advanced ecological genetics into ecological genomics and analyzed globally ecological, demographic, and life history variables in 1,200 diverse species across life, thousands of populations, and tens of thousands of individuals tested mostly for allozyme and partly for DNA diversity. Likewise, we tested thermal, chemical, climatic, and biotic stresses in several model organisms. Recently, we introduced genetic maps and quantitative trait loci to elucidate the genetic basis of adaptation and speciation. The genome–phenome holistic model was deciphered by the global regressive, progressive, and convergent evolution of subterranean mammals. Our results indicate abundant genotypic and phenotypic diversity in nature. The organization and evolution of molecular and organismal diversity in nature at global, regional, and local scales are nonrandom and structured; display regularities across life; and are positively correlated with, and partly predictable by, abiotic and biotic environmental heterogeneity and stress. Biodiversity evolution, even in small isolated populations, is primarily driven by natural selection, including diversifying, balancing, cyclical, and purifying selective regimes, interacting with, but ultimately overriding, the effects of mutation, migration, and stochasticity.

Heat-Stress Response of Maize Mitochondria1

We have identified maize (Zea mays L. inbred B73) mitochondrial homologs of the Escherichia coli molecular chaperones DnaK (HSP70) and GroEL (cpn60) using two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblots. During heat stress (42°C for 4 h), levels of HSP70 and cpn60 proteins did not change significantly. In contrast, levels of two 22-kD proteins increased dramatically (HSP22). Monoclonal antibodies were developed to maize HSP70, cpn60, and HSP22. The monoclonal antibodies were characterized with regard to their cross-reactivity to chloroplastic, cytosolic, and mitochondrial fractions, and to different plant species. Expression of mitochondrial HSP22 was evaluated with regard to induction temperature, time required for induction, and time required for degradation upon relief of stress. Maximal HSP22 expression occurred in etiolated seedling mitochondria after 5 h of a +13°C heat stress. Upon relief of heat stress, the HSP22 proteins disappeared with a half-life of about 4 h and were undetectable after 21 h of recovery. Under continuous heat-stress conditions, the level of HSP22 remained high. A cDNA for maize mitochondrial HSP22 was cloned and extended to full length with sequences from an expressed sequence tag database. Sequence analysis indicated that HSP22 is a member of the plant small heat-shock protein superfamily.

Cellular stress inhibits transposition of the yeast retrovirus-like element Ty3 by a ubiquitin-dependent block of virus-like particle formation.

Many stress proteins and their cognates function as molecular chaperones or as components of proteolytic systems. Viral infection can stimulate synthesis of stress proteins and particular associations of viral and stress proteins have been documented. However, demonstrations of functions for stress proteins in viral life cycles are few. We have initiated an investigation of the roles of stress proteins in eukaryotic viral life cycles using as a model the Ty3 retrovirus-like element of Saccharomyces cerevisiae. During stress, Ty3 transposition is inhibited; Ty3 DNA is not synthesized and, although precursor proteins are detected, mature Ty3 proteins and virus-like particles (VLPs) do not accumulate. The same phenotype is observed in the constitutively stressed ssa1 ssa2 mutant, which lacks two cytoplasmic members of the hsp70 family of chaperones. Ty3 VLPs preformed under nonstress conditions are degraded more rapidly if cells are shifted from 30 degrees C to 37 degrees C. These results suggest that Ty3 VLPs are destroyed by cellular stress proteins. Elevated expression of the yeast UBP3 gene, which encodes a protease that removes ubiquitin from proteins, allows mature Ty3 proteins and VLPs to accumulate in the ssa1 ssa2 mutant, suggesting that, at least under stress conditions, ubiquitination plays a role in regulating Ty3 transposition.

Persistent elevations of cerebrospinal fluid concentrations of corticotropin-releasing factor in adult nonhuman primates exposed to early-life stressors: implications for the pathophysiology of mood and anxiety disorders.

There is increasing evidence for an important role of adverse early experience on the development of major psychiatric disorders in adulthood. Corticotropin-releasing factor (CRF), an endogenous neuropeptide, is the primary physiological regulator of the mammalian stress response. Grown nonhuman primates who were exposed as infants to adverse early rearing conditions were studied to determine if long-term alterations of CRF neuronal systems had occurred following the early stressor. In comparison to monkeys reared by mothers foraging under predictable conditions, infant monkeys raised by mothers foraging under unpredictable conditions exhibited persistently elevated cerebrospinal fluid (CSF) concentrations of CRF. Because hyperactivity of CRF-releasing neurons has been implicated in the pathophysiology of certain human affective and anxiety disorders, the present finding provides a potential neurobiological mechanism by which early-life stressors may contribute to adult psychopathology.

Life satisfaction and health related quality of life during pregnancy and puerperium

Poster submitted to the 22nd International Conference Stress and Anxiety Research Society (STAR), Palma de Mallorca, July, 12-14, 2001.

Psychological Homelessness and Enculturative Stress among US-Deported Salvadorans: A Preliminary Study with a Novel Approach

The purpose of this study was to examine the construct psychological homelessness—feelings of not belonging in one’s home country—within the context of deported Salvadorans’ enculturation to El Salvador. Participants (n = 66) who had been deported from the United States completed a set of questionnaires related to their deportation experience. Results indicated that deportees, in various degrees, experienced the phenomenon of psychological homelessness and enculturative stress related to living in El Salvador. As hypothesized, enculturative stress related to re-adapting to life in El Salvador significantly correlated with psychological homelessness after controlling for time spent in the United States, acculturation, and enculturation. Additional analyses revealed that maladaptive cognitions related to the deportation experience also predicted psychological homelessness. Our findings suggest psychological homelessness appears to be a valid construct and is experienced by many undocumented immigrants.

Qualidade do sono e suas implicações ao nível da ansiedade, depressão e stress nos estudantes do ensino superior

O sono é imprescindível à existência humana, assumindo uma panóplia de funções cruciais nas diferentes faixas etárias. São inúmeros os fatores que podem contribuir para a sua alteração, sendo a vida universitária um deles. Tendo em conta os dados de incidência e prevalência de alterações neurocognitivas na população portuguesa, torna-se fundamental o estudo da qualidade do sono e as suas implicações a nível da ansiedade, depressão e stress nos estudantes de Ensino Superior do Instituto Politécnico de Bragança. Objetivou-se “Avaliar a qualidade do sono dos estudantes do ensino superior” e “Analisar os níveis de ansiedade, depressão e stress vivenciados pelos estudantes do ensino superior”. Face aos objetivos delineados optou-se por um estudo descritivo-correlacional inserido no paradigma quantitativo e num plano transversal, com uma amostragem não probabilística por conveniência de 358 estudantes representativos do Instituto Politécnico de Bragança. Para a colheita de dados utilizou-se uma Ficha Sociodemográfica, o Índice de Qualidade de Sono de Pittsburgh (IQSP) de Ramalho (2008) e a Escala de Ansiedade, Depressão e Stress (EADS-21) de Pais Ribeiro, Honrado e Leal (2004). Como principais resultados, destaca-se a qualidade de sono, evidenciando-se que 53,6% (192) dos estudantes apresenta má qualidade de sono e os restantes 46,4% (166) têm boa qualidade de sono. Os estudantes com má qualidade de sono apresentaram níveis médios de stress, ansiedade e depressão mais elevados que os estudantes com boa qualidade de sono. Os níveis de stress, ansiedade e depressão evidenciados nos estudantes foram considerados díspares entre eles, sendo que o stress foi o mais significativo. Ao constatarmos que a má qualidade de sono é frequente nos estudantes do ensino superior tendo esta repercussões na sua saúde física e mental, concluímos que estamos perante um risco de saúde pública.

Energy Signaling in the Regulation of Gene Expression during Stress

Maintenance of homeostasis is pivotal to all forms of life. In the case of plants, homeostasis is constantly threatened by the inability to escape environmental fluctuations, and therefore sensitive mechanisms must have evolved to allow rapid perception of environmental cues and concomitant modification of growth and developmental patterns for adaptation and survival. Re-establishment of homeostasis in response to environmental perturbations requires reprogramming of metabolism and gene expression to shunt energy sources from growth-related biosynthetic processes to defense, acclimation, and, ultimately, adaptation. Failure to mount an initial 'emergency' response may result in nutrient deprivation and irreversible senescence and cell death. Early signaling events largely determine the capacity of plants to orchestrate a successful adaptive response. Early events, on the other hand, are likely to be shared by different conditions through the generation of similar signals and before more specific responses are elaborated. Recent studies lend credence to this hypothesis, underpinning the importance of a shared energy signal in the transcriptional response to various types of stress. Energy deficiency is associated with most environmental perturbations due to their direct or indirect deleterious impact on photosynthesis and/or respiration. Several systems are known to have evolved for monitoring the available resources and triggering metabolic, growth, and developmental decisions accordingly. In doing so, energy-sensing systems regulate gene expression at multiple levels to allow flexibility in the diversity and the kinetics of the stress response.