The role of cold stress in predicting extra cardiovascular and respiratory admissions

Although several studies have examined effects of air temperature and/or other meteorological variables separately on disease rates, the relationship of meteorological variables and human disease is, in fact, rather complex in the “real-world” [1,2] including the number of potential variables to be considered and their weighting. In other words, 1 °C of air temperature difference in a warm climate may not necessarily mean the same in a cold climate across regions on Earth [3,4]. Why some seasonality was observed in certain regions at certain times only is likely due in part to the imprecise weather estimation from mean, maximum, or minimum air temperature or the definition of study catchments or time period to be included.

A conserved role for p48 homologs in protecting dopaminergic neurons from oxidative stress.

Parkinson's disease (PD) is the most common neurodegenerative movement disorder characterized by the progressive loss of dopaminergic (DA) neurons. Both environmental and genetic factors are thought to contribute to the pathogenesis of PD. Although several genes linked to rare familial PD have been identified, endogenous risk factors for sporadic PD, which account for the majority of PD cases, remain largely unknown. Genome-wide association studies have identified many single nucleotide polymorphisms associated with sporadic PD in neurodevelopmental genes including the transcription factor p48/ptf1a. Here we investigate whether p48 plays a role in the survival of DA neurons in Drosophila melanogaster and Caenorhabditis elegans. We show that a Drosophila p48 homolog, 48-related-2 (Fer2), is expressed in and required for the development and survival of DA neurons in the protocerebral anterior medial (PAM) cluster. Loss of Fer2 expression in adulthood causes progressive PAM neuron degeneration in aging flies along with mitochondrial dysfunction and elevated reactive oxygen species (ROS) production, leading to the progressive locomotor deficits. The oxidative stress challenge upregulates Fer2 expression and exacerbates the PAM neuron degeneration in Fer2 loss-of-function mutants. hlh-13, the worm homolog of p48, is also expressed in DA neurons. Unlike the fly counterpart, hlh-13 loss-of-function does not impair development or survival of DA neurons under normal growth conditions. Yet, similar to Fer2, hlh-13 expression is upregulated upon an acute oxidative challenge and is required for the survival of DA neurons under oxidative stress in adult worms. Taken together, our results indicate that p48 homologs share a role in protecting DA neurons from oxidative stress and degeneration, and suggest that loss-of-function of p48 homologs in flies and worms provides novel tools to study gene-environmental interactions affecting DA neuron survival.

Oxidative stress and inflammation response after nanoparticle exposure: differences between human lung cell monocultures and an advanced three-dimensional model of the human epithelial airways

Combustion-derived and manufactured nanoparticles (NPs) are known to provoke oxidative stress and inflammatory responses in human lung cells; therefore, they play an important role during the development of adverse health effects. As the lungs are composed of more than 40 different cell types, it is of particular interest to perform toxicological studies with co-cultures systems, rather than with monocultures of only one cell type, to gain a better understanding of complex cellular reactions upon exposure to toxic substances. Monocultures of A549 human epithelial lung cells, human monocyte-derived macrophages and monocyte-derived dendritic cells (MDDCs) as well as triple cell co-cultures consisting of all three cell types were exposed to combustion-derived NPs (diesel exhaust particles) and to manufactured NPs (titanium dioxide and single-walled carbon nanotubes). The penetration of particles into cells was analysed by transmission electron microscopy. The amount of intracellular reactive oxygen species (ROS), the total antioxidant capacity (TAC) and the production of tumour necrosis factor (TNF)-alpha and interleukin (IL)-8 were quantified. The results of the monocultures were summed with an adjustment for the number of each single cell type in the triple cell co-culture. All three particle types were found in all cell and culture types. The production of ROS was induced by all particle types in all cell cultures except in monocultures of MDDCs. The TAC and the (pro-)inflammatory reactions were not statistically significantly increased by particle exposure in any of the cell cultures. Interestingly, in the triple cell co-cultures, the TAC and IL-8 concentrations were lower and the TNF-alpha concentrations were higher than the expected values calculated from the monocultures. The interplay of different lung cell types seems to substantially modulate the oxidative stress and the inflammatory responses after NP exposure.

Paracrine factors secreted by endothelial progenitor cells prevent oxidative stress-induced apoptosis of mature endothelial cells

Endothelial progenitor cells (EPC) play a fundamental role in tissue regeneration and vascular repair. Current research suggests that EPC are more resistant to oxidative stress as compared to differentiated endothelial cells. Here we hypothesized that EPC not only possess the ability to protect themselves against oxidative stress but also confer this protection upon differentiated endothelial cells by release of paracrine factors. To test this hypothesis, HUVEC incubated with conditioned medium obtained from early EPC cultures (EPC-CM) were exposed to H2O2 to assess the accumulation of intracellular ROS, extent of apoptosis and endothelial cell functionality. Under oxidative stress conditions HUVEC treated with EPC-CM exhibited substantially lower levels of intracellular oxidative stress (0.2+/-0.02 vs. 0.4+/-0.03 relative fluorescence units, p<0.05) compared to control medium. Moreover, the incubation with EPC-CM elevated the expression level of antioxidant enzymes in HUVEC (catalase: 2.6+/-0.4; copper/zinc superoxide dismutase (Cu/ZnSOD): 1.6+/-0.1; manganese superoxide dismutase (MnSOD): 1.4+/-0.1-fold increase compared to control, all p<0.05). Furthermore, EPC-CM had the distinct potential to reverse the functional impairment of HUVEC as measured by their capability to form tubular structures in vitro. Finally, incubation of HUVEC with EPC-CM resulted in a significant reduction of apoptosis (0.34+/-0.01 vs. 1.52+/-0.12 relative fluorescence units, p<0.01) accompanied by an increased expression ratio of the anti/pro-apoptotic factors Bcl-2/Bax to 2.9+/-0.7-fold (compared to control, p<0.05). Most importantly, neutralization of selected cytokines such as VEGF, HGF, IL-8 and MMP-9 did not significantly reverse the cyto-protective effect of EPC-CM (p>0.05), suggesting that soluble factors secreted by EPC, possibly via broad synergistic actions, exert strong cyto-protective properties on differentiated endothelium through modulation of intracellular antioxidant defensive mechanisms and pro-survival signals.

Cardiovascular stress reactivity and recovery in Bulimia nervosa and Binge Eating Disorder

Stress plays a role in the pathology of bulimia nervosa and binge eating disorders, but it is unclear whether they involve similar disturbances of biological stress responses.

The role of autophagy in anticancer therapy: promises and uncertainties

Autophagy (literally self-eating) is a catabolic mechanism involved in the recycling and turnover of cytoplasmic constituents. Although often referred to as type II programmed cell death, autophagy is primarily a survival rather than a cell death mechanism in response to different stress stimuli. Autophagy is a process in which part of the cytoplasm or entire organelles are sequestered into double-membrane vesicles, called autophagosomes, which ultimately fuse with lysosomes to degrade their contents. Studies show that autophagy is associated with a number of pathological conditions, including cancer, infectious diseases, myopathies and neurodegenerative disorders. With respect to cancer, it has been suggested that the early stages of tumourigenesis are associated with downregulation of autophagy-related (ATG) genes. Indeed, several ATG genes display tumour suppressor function, including Beclin1, which is frequently hemizygously deleted in breast cancer cells. Conversely, in advanced stages of tumourigenesis or during anticancer therapy, autophagy may promote survival of tumour cells in adverse environmental conditions. Therefore, a thorough understanding of autophagy in different cancer types and stages is a prerequisite to determine an autophagy-activating or autophagy-inhibiting treatment strategy.

Mood and nonmood components of perceived stress and exacerbation of Crohnʼs disease

BACKGROUND: Diverse psychological factors are involved in the pathophysiology of stress. In order to devise effective intervention strategies, it is important to elucidate which factors play the most important role in the association between psychological stress and exacerbation of Crohn's disease (CD). We hypothesized that the association between perceived stress and exacerbation of CD would remain after removal of mood and anxiety components, which are largely involved in stress perception. METHODS: In all, 468 adults with CD were recruited and followed in different hospitals and private practices of Switzerland for 18 months. At inclusion, patients completed the Perceived Stress Questionnaire and anxiety and depression were assessed using the Hospital Anxiety and Depression Scale. During the follow-up, gastroenterologists assessed whether patients presented with a CD exacerbation. By means of binary logistic regression analysis, we estimated the factor by which one standard deviation of perceived stress would increase the odds of exacerbation of CD with and without controlling for anxiety and depression. RESULTS: The odds of exacerbation of CD increased by 1.85 times (95% confidence interval 1.43-2.40, P < 0.001) for 1 standard deviation of perceived stress. After removing the anxiety and depression components, the residuals of perceived stress were no longer associated with exacerbation of CD. CONCLUSIONS: The association between perceived stress and exacerbation of CD was fully attributable to the mood components, specifically anxiety and depression. Future interventional studies should evaluate the treatment of anxiety and depression as a strategy for potential prevention of CD exacerbations. (Inflamm Bowel Dis 2011;).

Self-efficacy buffers the relationship between dementia caregiving stress and circulating concentrations of the proinflammatory cytokine interleukin-6

the proinflammatory cytokine interleukin (IL)-6 has been linked with health morbidity, particularly risk for cardiovascular disease (CVD). The purpose of this study was to investigate the potential protective role of coping self-efficacy on the relationship between caregiving stress and circulating concentrations of IL-6.

Carotid plaque in Alzheimer caregivers and the role of sympathoadrenal arousal

To test the hypothesis that those who provide care for a spouse diagnosed with Alzheimer's disease would have increased prevalence of carotid artery plaque compared with noncaregiving controls and that prolonged sympathoadrenal arousal to acute stress would relate to this difference. Providing care for a spouse with Alzheimer's disease has been associated with an increased risk of coronary heart disease, potentially due to the impact of caregiving stress on the atherosclerotic disease process.

Effect of Acute Psychological Stress on Prefrontal GABA Concentration Determined by Proton Magnetic Resonance Spectroscopy

Objective Impaired function of the central gamma-aminobutyric acid (GABA) system, which provides the brain’s major inhibitory pathways, is thought to play an important role in the pathophysiology of anxiety disorders. The effect of acute psychological stress on the human GABA-ergic system is still unknown, however. The purpose of this study was to determine the effect of acute stress on prefrontal GABA levels. Method A recently developed noninvasive magnetic resonance spectroscopy method was used to measure changes in the GABA concentration of the prefrontal cortex in 10 healthy human subjects during a threat-of-shock condition and during a safe condition (two sessions on different days). The main outcome measure was the mean GABA concentration within a 3×3×2-cm3 voxel selected from the medial prefrontal cortex. Results Prefrontal GABA decreased by approximately 18% in the threat-of-shock condition relative to the safe condition. This reduction was specific to GABA, since the concentrations of N-acetyl-aspartate, choline-containing compounds, and glutamate/glutamine levels obtained in the same spectra did not change significantly. Conclusions This result appeared compatible with evidence from preclinical studies in rodents, which showed rapid presynaptic down-regulation of GABA-ergic neurotransmission in response to acute psychological stress. The molecular mechanism and functional significance of this reduced inhibitory effect of acute psychological stress in relation to impaired GABA-ergic function in anxiety disorders merit further investigation.

The transcriptional regulator megakaryoblastic leukemia-1 mediates serum response factor-independent activation of tenascin-C transcription by mechanical stress

The extracellular matrix protein tenascin-C (TNC) is up-regulated in processes influenced by mechanical stress, such as inflammation, tissue remodeling, wound healing, and tumorigenesis. Cyclic strain-induced TNC expression depends on RhoA-actin signaling, the pathway that regulates transcriptional activity of serum response factor (SRF) by its coactivator megakaryoblastic leukemia-1 (MKL1). Therefore, we tested whether MKL1 controls TNC transcription. We demonstrate that overexpression of MKL1 strongly induces TNC expression in mouse NIH3T3 fibroblasts and normal HC11 and transformed 4T1 mammary epithelial cells. Part of the induction was dependant on SRF and a newly identified atypical CArG box in the TNC promoter. Another part was independent of SRF but required the SAP domain of MKL1. An MKL1 mutant incapable of binding to SRF still strongly induced TNC, while induction of the SRF target c-fos was abolished. Cyclic strain failed to induce TNC in MKL1-deficient but not in SRF-deficient fibroblasts, and strain-induced TNC expression strongly depended on the SAP domain of MKL1. Promoter-reporter and chromatin immunoprecipitation experiments unraveled a SAP-dependent, SRF-independent interaction of MKL1 with the proximal promoter region of TNC, attributing for the first time a functional role to the SAP domain of MKL1 in regulating gene expression.

Role of AMP-activated protein kinase on steroid hormone biosynthesis in adrenal NCI-H295R cells

Regulation of human androgen biosynthesis is poorly understood. However, detailed knowledge is needed to eventually solve disorders with androgen dysbalance. We showed that starvation growth conditions shift steroidogenesis of human adrenal NCI-H295R cells towards androgen production attributable to decreased HSD3B2 expression and activity and increased CYP17A1 phosphorylation and 17,20-lyase activity. Generally, starvation induces stress and energy deprivation that need to be counteracted to maintain proper cell functions. AMP-activated protein kinase (AMPK) is a master energy sensor that regulates cellular energy balance. AMPK regulates steroidogenesis in the gonad. Therefore, we investigated whether AMPK is also a regulator of adrenal steroidogenesis. We hypothesized that starvation uses AMPK signaling to enhance androgen production in NCI-H295R cells. We found that AMPK subunits are expressed in NCI-H295 cells, normal adrenal tissue and human as well as pig ovary cells. Starvation growth conditions decreased phosphorylation, but not activity of AMPK in NCI-H295 cells. In contrast, the AMPK activator 5-aminoimidazole-4-carboxamide (AICAR) increased AMPKα phosphorylation and increased CYP17A1-17,20 lyase activity. Compound C (an AMPK inhibitor), directly inhibited CYP17A1 activities and can therefore not be used for AMPK signaling studies in steroidogenesis. HSD3B2 activity was neither altered by AICAR nor compound C. Starvation did not affect mitochondrial respiratory chain function in NCI-H295R cells suggesting that there is no indirect energy effect on AMPK through this avenue. In summary, starvation-mediated increase of androgen production in NCI-H295 cells does not seem to be mediated by AMPK signaling. But AMPK activation can enhance androgen production through a specific increase in CYP17A1-17,20 lyase activity.

Psychosocial stress and cardiovascular risk : current opinion

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Epidemiologic research of the last half-century has clearly shown that psychosocial factors related to the social environment, personality characteristics, and negative affect increase the risk of incident CVD and also impact prognosis of cardiac patients. Several mechanisms may explain this link, including a genetic predisposition, poor lifestyle choices, low adherence to health recommendations, and direct pathophysiologic perturbations. The latter include alteration of the hypothalamic-pituitary adrenal axis and autonomic dysfunction resulting in endothelial dysfunction, inflammation, and a prothrombotic state further downstream. Screening for psychosocial factors seems appropriate as part of the standard history and based on the clinician's knowledge of the patient and the purpose of the visit. Psychological interventions generally alleviate distress in cardiac patients, but whether they reduce the risk of hard cardiovascular endpoints and all-cause mortality is less evident. Cardiac patients with more severe depression may particularly profit from antidepressant medications. Due to their pharmacologic properties, selective serotonin reuptake inhibitors were shown to improve cardiovascular outcome. The most effective psychosocial treatment is multicomponent therapy that combines elements of cognitive behaviour therapy ("stress management") and changes in health behaviours, including the adoption of a regular exercise regimen. Gender-specific issues should probably be considered. The field of behavioural cardiology has accumulated a wealth of epidemiological, mechanistic and clinical knowledge that undoubtedly has furthered our understanding about the important role of psychosocial risk factors in patients with a heart disease.

Taiji practice attenuates psychobiological stress reactivity - A randomized controlled trial in healthy subjects

Background: Stress reducing effects of Taiji, a mindful and gentle form of body movement, have been reported in previous studies, but standardized and controlled experimental studies are scarce. The present study investigates the effect of regular Taiji practice on psychobiological stress response in healthy men and women. Methods: 70 participants were randomly assigned to either Taiji classes or a waiting list. After 3 months, 26 (8 men, 18 women) persons in the Taiji group and 23 (9 men, 14 women) in the waiting control group underwent a standardized psychosocial stress test combining public speaking and mental arithmetic in front of an audience. Salivary cortisol and α-amylase, heart rate, and psychological responses to psychosocial stress were compared between the study groups. (ClinicalTrials.gov number, NCT01122706.) Results: Stress induced characteristic changes in all psychological and physiological measures. Compared to controls, Taiji participants exhibited a significantly lower stress reactivity of cortisol (p = .028) and heart rate (p = .028), as well as lower α-amylase levels (p = .049). They reported a lower increase in perceived stressfulness (p = .006) and maintained a higher level of calmness (p = .019) in response to psychosocial stress. Conclusion: Our results consistently suggest that practicing Taiji attenuates psychobiological stress reactivity in healthy subjects. This may underline the role of Taiji as a useful mind–body practice for stress prevention.

Functional and physiological role of vitamin C transporters

Vitamin C (ascorbic acid) is required for the synthesis of collagen, carnitine, catecholamine and the neurotransmitter norepinephrine. Vitamin C also plays an important role in protection against oxidative stress. Transporters for vitamin C and its oxidized form dehydroascorbate (DHA) are crucial to keep vitamin concentrations optimal in the body. The human SLC23 family consists of the Na(+)-dependent vitamin C transporters SVCT1 (SLC23A1) and SVCT2 (SLC23A2) and the orphan transporter SVCT3 (SLC23A3). Phylogenetically, the SLC23 family belongs to the nucleobase-ascorbate transporter family although no specificity for nucleobases has yet been demonstrated for the human members of this family. In fact, the SVCT1 and SVCT2 transporters are rather specific for ascorbic acid. SVCT1 is expressed in epithelial tissues such as intestine, where it contributes to the maintenance of whole-body ascorbic acid levels, whereas the expression of SVCT2 is relatively widespread either to protect metabolically active cells and specialized tissues from oxidative stress or to deliver ascorbic acid to tissues that are in high demand of the vitamin for enzymatic reactions. DHA, the oxidized form of ascorbic acid is taken up and distributed in the body by facilitated transport via members of the SLC2/GLUT family (GLUT1, GLUT3, and GLUT4). Although, the main focus of this review is on the SLC23 family of ascorbic acid transporters, transporters of DHA and nucleobases are also briefly discussed for completeness.