Stress Response Profiles Research Articles

Transcriptional profiling of stress response in cultured porcine islets

Cell-based diabetes therapy may be achieved through xenotransplantation of adult porcine islets, but tissue quality and immunoreactivity barriers need to be overcome. Early identification and exclusion of irreversibly stressed and dying islets may improve transplant outcomes. We used oligonucleotide microarray and quantitative RT-PCR to identify molecular markers of physiological and immunological stress in porcine islets cultured under stress conditions of elevated glucose (16.7mM), inflammatory cytokine addition (IL-1β, TNF-α, and IFN-γ), or both, for 48h. Hyperglycemic conditions were associated with increased thioredoxin interacting protein and metabolic process mRNAs, as observed in rodent and primate species. Cytokine treatment increased expression of JAK-STAT pathway components, oxidative stress (transglutaminase 2), and β cell dysfunction genes. Transglutaminase 2 induction is unique to porcine islets. Biomarkers involved in hyperglycemia and islet inflammation may serve as novel targets for improving and monitoring isolated porcine islet function and viability.

The use of pre‐operative intrathecal morphine for analgesia following coronary artery bypass surgery

With the emergence of rapid extubation protocols following cardiac surgery, providing adequate analgesia in the early postoperative period is important. This prospective randomised double-blind study investigated the benefits of pre-operative intrathecal administration of low dose morphine in patients undergoing coronary artery bypass graft surgery. Postoperative analgesia, pulmonary function, stress response and postoperative recovery profile were assessed. Thirty patients were allocated into two groups, receiving either 500 mug of morphine intrathecally prior to anaesthesia and intravenous patient-controlled analgesia with morphine postoperatively following tracheal extubation, or only postoperative intravenous patient-controlled analgesia. In the intrathecal group, the total consumption of intravenous morphine following surgery was significantly reduced by 40% and patients reported lower pain scores at rest, during the first 24 h following extubation. Peak expiratory flow rate was greater and postoperative catecholamine release was significantly lower. Patients in the control group had a higher incidence of reduced respiratory rate following extubation.

Management of Physiological Stress in Finfish Aquaculture

AbstractPhysiological stress is a nonspecific response common to all vertebrate organisms initiated by many types of environmental changes. Stress in fish can be characterized by physiological changes such as plasma cortisol, glucose, lactate, and electrolyte concentrations and is quantitatively related to the severity and longevity of the stressor. A hierarchy is evident among the physiological changes, such that adrenalin from activation of the sympathetic nervous system is released most rapidly, followed by cortisol, and then glucose. Plasma electrolyte disturbances may not occur until the stress is severe and present for an extended time. Adrenalin increases plasma glucose by stimulating liver glycogenolysis, which represents a metabolic energy cost to the fish. The functions of cortisol include possible induction of gluconeogenesis and suppression of the inflammatory response. Maintaining osmoregulatory homeostasis is an energetically expensive process, and disturbances deplete energy reserves. Recent experiments have shown the importance of distinguishing between acute and chronic responses to stress. Acute responses to stressors may be beneficial to the fish and extend their normal adaptive ability, whereas chronic exposure to stressful conditions may result in decreased performance or survival. The physiological stress response in fish culture has been shown to be altered by hatchery conditions and genetic selection. Management practices and selection pressures affect the stress response, which requires that the ultimate use of the fish be considered during rearing. Commercial food fish aquaculture, which involves rearing fish at very high densities, requires minimizing stressors such as water‐quality deterioration, disease treatment, and handling to maintain healthy growing fish. Fish raised for stocking into the wild might benefit from a more robust stress response to prepare them for survival in a natural environment. Present information does not allow for the selection of the most desirable stress response profile that would benefit fish reared for different purposes.

Comparative transcriptional profiling of the bacterial stress response in temperature and chemically-induced recombinant E. coli processes

Comparative transcriptional profiling of the bacterial stress response in temperature and chemically-induced recombinant E. coli processes

Role of the Alkali Labile Sites, Reactive Oxygen Species and Antioxidants in DNA Damage Induced by Methylated Trivalent Metabolites of Inorganic Arsenic

In the last decade arsenic metabolism has become an important matter of discussion. Methylation of inorganic arsenic (iAs) to monomethylarsonic acid (MMA(V)) and dimethylarsinic acid (DMA(V)) is considered to decrease arsenic toxicity. However, in addition to these pentavalent metabolites, the trivalent metabolites monomethylarsonous (MMA(III)) and dimethylarsinous acid (DMA(III)) have been identified recently as intermediates in the metabolic pathway of arsenic in cultured human cells. To examine the role of oxidative damage in the generation of DNA strand breaks by methylated trivalent arsenic metabolites, we treated human lymphocytes with both metabolites at non-cytotoxic concentrations. We further tested whether these effects are sensitive to modulation by the antioxidants ascorbate (Vitamin C) and selenomethionine (Se-Met). Both trivalent metabolites produced oxidative stress related DNA damage, consisting of single strand breaks and alkali-labile sites, with MMA(III) being more potent at low concentrations than DMA(III). Neither MMA(III) nor DMA(III) induced DNA-double strand breaks. The oxidative stress response profiles of the metabolites were parallel as determined by lipid peroxidation induction. MMA(III) induced peroxidation from the lowest concentration tested, while effects of DMA(III) were apparent only at concentrations above 10 muM. The antioxidant Se-Met exhibited a more pronounced inhibition of trivalent arsenic metabolite-induced oxidative-DNA damage than did vitamin C. The present findings suggest that DNA damage by methylated trivalent metabolites at non-cytotoxic concentrations may be mediated by a mix of reactive oxygen and nitrogen oxidized species.

How does yeast respond to pressure?

The brewing and baking yeast Saccharomyces cerevisiae has been used as a model for stress response studies of eukaryotic cells. In this review we focus on the effect of high hydrostatic pressure (HHP) on S. cerevisiae. HHP exerts a broad effect on yeast cells characteristic of common stresses, mainly associated with protein alteration and lipid bilayer phase transition. Like most stresses, pressure induces cell cycle arrest. Below 50 MPa (500 atm) yeast cell morphology is unaffected whereas above 220 MPa wild-type cells are killed. S. cerevisiae cells can acquire barotolerance if they are pretreated with a sublethal stress due to temperature, ethanol, hydrogen peroxide, or pressure. Nevertheless, pressure only leads to protection against severe stress if, after pressure pretreatment, the cells are also re-incubated at room pressure. We attribute this effect to the inhibition of the protein synthesis apparatus under HHP. The global genome expression analysis of S. cerevisiae cells submitted to HHP revealed a stress response profile. The majority of the up-regulated genes are involved in stress defense and carbohydrate metabolism while most repressed genes belong to the cell cycle progression and protein synthesis categories. However, the signaling pathway involved in the pressure response is still to be elucidated. Nitric oxide, a signaling molecule involved in the regulation of a large number of cellular functions, confers baroprotection. Furthermore, S. cerevisiae cells in the early exponential phase submitted to 50-MPa pressure show induction of the expression level of the nitric oxide synthase inducible isoform. As pressure becomes an important biotechnological tool, studies concerning this kind of stress in microorganisms are imperative.

High-throughput phenotypic profiling of gene–environment interactions by quantitative growth curve analysis in Saccharomyces cerevisiae

Cell-based assays are widely used in high-throughput screening to determine the effects of toxicants and drugs on their biological targets. To enable a functional genomics modeling of gene–environment interactions, quantitative assays are required both for gene expression and for the phenotypic responses to environmental challenge. To address this need, we describe an automated high-throughput methodology that provides phenotypic profiling of the cellular responses to environmental stress in Saccharomyces cerevisiae. Standardized assay conditions enable the use of a single metric value to quantify yeast microculture growth curves. This assay format allows precise control of both genetic and environmental determinants of the cellular responses to oxidative stress, a common mechanism of environmental insult. These yeast-cell-based assays are validated with hydrogen peroxide, a simple direct-acting oxidant. Phenotypic profiling of the oxidative stress response of a yap1 mutant strain demonstrates the mechanistic analysis of genetic susceptibility to oxidative stress. As a proof of concept for analysis of more complex gene–environment interactions, we describe a combinatorial assay design for phenotypic profiling of the cellular responses to tert-butyl hydroperoxide, a complex oxidant that is actively metabolized by its target cells. Thus, the yeast microculture assay format supports comprehensive applications in toxicogenomics.

Some Aspects of the Stress Responses to Road Transport in Thoroughbred Horses with Special Reference to Shipping Fever

We performed two sets of experiments consisting of 36 hr and 41 hr of transportation to elucidate the road transit-induced stress response's profiles in horses with clinical signs of respiratory disease (affected horses) and horses without clinical signs of respiratory disease (unaffected horses). In both sets of experiments, affected horses showed a significantly greater increase or decrease in levels of the indices of the stress response, i.e., eosinophil count, erythrocyte sedimentation rate, levels of serum glucose, adrenocorticotropic hormone (ACTH) and 11-hydroxycorticosteroid (11-OHCS) than unaffected horses after road transportation. Compared with unaffected horses, affected horses had a different pattern of changes in indices of the stress response, suggesting that they failed to adapt to transportation.

Survival, the hormonal stress response and UV‐B avoidance in Cascades Frog tadpoles (Rana cascadae) exposed to UV‐B radiation

Summary Despite the increasing occurrence of global environmental changes, including increases in ultraviolet‐B radiation (UV‐B; 280–320 nm), little is known about how factors such as UV‐B affect animals physiologically. Amphibians provide a good model for examining physiological effects of UV‐B exposure because studies documenting both lethal and sub‐lethal effects have been completed on many species. This study examines survival and the hormonal stress response, as measured by whole body levels of the glucocorticoid hormone corticosterone, of Cascades Frog, Rana cascadae, tadpoles exposed to ambient UV‐B in the field for either 7 or 42 days. There were no differences in corticosterone levels between UV‐B exposed and non‐exposed tadpoles at either time point. However, after 42 days, survival was significantly higher in tadpoles shielded from UV‐B. A stress response profile performed in the field demonstrated that young R. cascadae tadpoles are able to respond to confinement stress with increasing corticosterone. In addition, results from UV‐B avoidance tests suggest that R. cascadae tadpoles do not avoid UV‐B. Thus, R. cascadae tadpoles may not perceive UV‐B radiation, which would explain why they do not respond hormonally to exposure, despite the potential for exposure to result in mortality.

The psychobiology of childhood stress.

Recent psychobiologic research has provided new insights into the interplay between constitutional and environmental etiologies in stress-induced childhood illness. Individual differences in both psychobiologic reactivity and physiologic self-regulation may substantially influence a child's internal stress responses. In addition, the physiologic consequences of a given environmental stressor may depend critically on the developmental stage in which the stressor occurs. Behavioral changes associated with early exposures to stressors may be linked to alterations in central nervous system monoamine production and metabolism. Evidence for developmental and psychobiologic changes in response to very early, even prenatal, stressors suggests that environmental and genetic contributions to stress response profiles may ultimately be difficult to disentangle.

Corticotropin-releasing factor antagonist reduces emotionality in socially defeated rats via direct neurotropic action

Introduction of a socially naive male rat into the home territory of a resident counterpart results in agonistic interactions, leading to the rapid social defeat of the intruder. Exposure to the aggressive resident produces a stress-response profile consisting of neuroendocrine activation and coping behaviors such as submission. The present studies examined the dependence of these adaptive responses on endogenous brain Corticotropin-Releasing Factor (CRF), a peptide hormone known to coordinate neuronally mediated- and pituitary-adrenal responses to stress. The elevated Plus-Maze was employed as an animal model of emotionality in which stressors reduce subsequent exploration of open maze arms without walls in favor of enclosed maze arms. A CRF antagonist, a-hel CRF 9−41, administered intracerebroventricularly (5 and 25 μg i.c.v.) immediately post-stress and 5 min prior to maze testing reversed the heightened emotionality produced by the resident exposure stressor. This action paralleled that of an anxiolytic dose of the short-acting benzodiazepine, midazolam (1.5 mg/kg i.p.). Intra-amygdaloid administration of lower doses of the CRF antagonist (125, 250 and 500 ng i.c.) also reversed, dose-dependently, the effect of exposure to an aggressive resident without altering the behavior of unstressed control animals. Further, the enhanced release of ACTH and corticosterone following social conflict was not modified over the short term by the intra-amygdaloid dose of CRF antagonist (250 ng i.c.) which was effective in reversing stress-induced hyper-emotionality. These results suggest that limbic system CRF substrates exert an anxiogenic effect on the exploratory behavior of socially defeated rats via a pituitary-adrenal-independent mechanism.

Behavioral, corticosterone, and prolactin responses to novel environment in rats with fornix transections.

These experiments examined the behavioral, corticosterone, and prolactin responses to a novel environmental in male rats with total fornix transections. During the initial exposure to the novel environment, rats with fornix transections exhibited increased latency to initiate activity and increased activity levels. There were no changes in frequency of rearing, frequency of interactions with objects in the environment, or defecation. Fornix transection was found to have no effect on resting levels of either corticosterone or prolactin but to alter significantly the stress-response profiles of each of these hormones. The corticosterone responses to the novel environment in rats with fornix lesions were of greater magnitude with no change in latency to respond or in recovery of resting levels, whereas the prolactin responses were of shorter latency with no change in magnitude or recovery or resting levels. Habituating to the novel environment by repeated exposure was found to decrease the corticosterone responses of rats with fornix lesions but not the responses of controls. The results are discussed in terms of differences between rats with fornix lesions and control rats in level of arousal and effect of experience in the environment.