Sister chromatid exchanges induced by behavioral stress

Stress, ageing and their influence on functional, cellular and molecular aspects of the immune system

The immune response is essential for keeping an organism healthy and for defending it from different types of pathogens. It is a complex system that consists of a large number of components performing different functions. The adequate and controlled interaction between these components is necessary for a robust and strong immune response. There are, however, many factors that interfere with the way the immune response functions. Stress and ageing now consistently appear in the literature as factors that act upon the immune system in the way that is often damaging. This review focuses on the role of stress and ageing in altering the robustness of the immune response first separately, and then simultaneously, discussing the effects that emerge from their interplay. The special focus is on the psychological stress and the impact that it has at different levels, from the whole system to the individual molecules, resulting in consequences for physical health.

Increased formation of sister chromatid exchanges, but not of micronuclei, in anaesthetists exposed to low levels of sevoflurane

We have assessed, for the first time, genotoxicity (i.e. sister chromatid exchanges and micronuclei) in anaesthetists exposed to a single volatile anaesthetic (sevoflurane) without nitrous oxide. The anaesthetists were exposed to an 8-h time-weighted average of 0.2 parts per million sevoflurane. Internists served as non-exposed controls. Mean (SD) sister chromatid exchanges per cell were significantly higher in anaesthetists compared to internists (6.6 (0.9) vs 5.1 (0.8); p < 0.001) whereas median (IQR [range]) micronuclei per 1000 binucleated cells did not differ (9.5 (6.3-10.8 [2.0-15.5]) vs 8.5 (6.0-10.5 [3.0-25.5]), respectively). Although the anaesthetists were exposed to rather low concentrations of sevoflurane, this 30% increase of sister chromatid exchanges is in agreement with a recently reported 300% increase with a high level exposure to sevoflurane and nitrous oxide. Omitting nitrous oxide does not normalise increased rates of sister chromatid exchanges.

Stress, depression, the immune system, and cancer

The links between the psychological and physiological features of cancer risk and progression have been studied through psychoneuroimmunology. The persistent activation of the hypothalamic-pituitary-adrenal (HPA) axis in the chronic stress response and in depression probably impairs the immune response and contributes to the development and progression of some types of cancer. Here, we overview the evidence that various cellular and molecular immunological factors are compromised in chronic stress and depression and discuss the clinical implications of these factors in the initiation and progression of cancer. The consecutive stages of the multistep immune reactions are either inhibited or enhanced as a result of previous or parallel stress experiences, depending on the type and intensity of the stressor and on the animal species, strain, sex, or age. In general, both stressors and depression are associated with the decreased cytotoxic T-cell and natural-killer-cell activities that affect processes such as immune surveillance of tumours, and with the events that modulate development and accumulation of somatic mutations and genomic instability. A better understanding of the bidirectional communication between the neuroendocrine and immune systems could contribute to new clinical and treatment strategies.

Psychoneuroimmunology: a theoretical basis for occupational therapy in oncology?

Psychoneuroimmunology is the scientific study of the physiological two-way link between the mind and the immune system. It is difficult to find published results of clinical controlled trials of the therapeutic effects of occupational therapy modalities in cancer care. The roots of occupational therapy have been neglected and perhaps forgotten in England's NHS, resulting in the loss of professional identity. The original occupational therapy ethos is, however, supported by psychoneuroimmunology research findings.

This article looks at the oncology-specific psychoneuroimmunology literature and its implications for cancer treatment. It highlights the point that further research based on psychoneuroimmunology could contribute to an evidence base for occupational therapy in oncology.

The effect of stress and in vivo vasoactive intestinal peptide (VIP) treatment on the response of isolated rat aorta to norepinephrine, angiotensin II and vasopressin, and adventitial mast cells

The effects of cold-restraint stress, repeated over 3 days, and treatment of rats with vasoactive intestinal peptide (VIP) on the contractile responses of isolated aorta to vasoconstrictors, and on aortic adventitial mast cells were investigated. Stress significantly reduced the contractile response of rat aorta smooth muscle to norepinephrine (NE), angiotensin II (Ang II) and vasopressin (VP). Decreased sensitivity to NE, Ang II and VP may result from decreased receptor density, and affinity or reduced effector efficacy. Stress induced degranulation, decreased the number and changed the granular content of mast cells; all degranulated mast cells were stained with alcian blue, and the percentage of safranin staining cells was decreased. Given prior to stress, VIP reversed the reduced contractile responses and sensitivity of aorta to NE and Ang II but had no effect on VP subsensitivity. VIP also inhibited stress-induced degranulation of mast cells, and after VIP only alcian blue-stained mast cells were seen. When VIP was given to non-stressed rats, the contractile response of the aorta to NE, but not Ang II or VP, was increased compared with control. Mast cell count was decreased in the adventitia of non-stressed VIP treated rats. The results indicate that stress decreases the heparin content of mast cells and VIP has an additive effect. In conclusion, VIP modulates both stress-induced mast cell activity and reduced sensitivity of aorta smooth muscle to NE and Ang II. It can be suggested that VIP may moderate some effects of stress on vascular pathophysiology.

Psychoneuroimmunology and cancer: fact or fiction?

There is substantial evidence from both healthy populations as well as individuals with cancer linking psychological stress with immune downregulation. This discussion highlights natural killer (NK) cells, because of the role that they may play in malignant disease. In addition, distress or depression is also associated with two important processes for carcinogenesis: poorer repair of damaged DNA, and alterations in apoptosis. Conversely, the possibility that psychological interventions may enhance immune function and survival among cancer patients clearly merits further exploration, as does the evidence suggesting that social support may be a key psychological mediator. These studies and others suggest that psychological or behavioural factors may influence the incidence or progression of cancer through psychosocial influences on immune function and other physiological pathways.

Increased levels of sister chromatid exchanges in military aircraft pilots

Sister chromatid exchanges (SCEs) were scored in lymphocytes of nine high-performance pilots of alphajet aircrafts and of ten control individuals from the same air base. Statistical analysis of the mean SCE count per cell in the total number of cells analyzed as well as in those having 12 or more SCEs (high-frequency cells, HFCs) revealed a significant difference between pilots and controls, after adjusting for the effect of smoking. Analysis of the cell cycle kinetic data (replication and mitotic indices) revealed no significant differences either between pilots and controls or between smokers and nonsmokers. Previously, we reported an increase in the SCE levels in workers of the aeronautical industry exposed to noise and whole-body vibration. The present results corroborate those findings and indicate that noise and whole-body vibration may cause genotoxic effects in man.

Sister chromatid exchange analysis in patients exposed to low dose of iodine-131 for thyroid scintigraphy

To determine the genotoxic risk associated with diagnostic exposure to low doses of iodine 131 (131I), sister chromatid exchange (SCE) analysis was performed in lymphocytes of 18 non-smoking women who received 370 kBq (10 microCi) intravenous 131I sodium iodide as an adjuvant for scintigraphy for diagnosing thyroid nodularity. SCE frequencies were measured before and after 131I administration. SCE results in the pre-treated phase were regarded as control. Although SCE values 24 h after 131I administration did not show a significant increment (p > 0.05), there was a significant increase 72 h after treatment (p < 0.05). These results indicate that genetic damage might be induced by low dose of 131I.

Sister chromatid exchange analysis in workers exposed to noise and vibration

Workers chronically exposed to whole-body vibration and noise are known to develop pathophysiological and psychological disturbances. The frequencies of sister chromatid exchanges (SCEs) and of cells with high frequencies of SCEs (HFCs) were analyzed in lymphocytes of 50 workers occupationally exposed to vibration and noise and of 34 controls. The exposed group included: individuals operating hand-vibrating tools (group 1), 'test-cell operators' (group 2) and 'run-up' operators (group 3) from an air base and helicopter pilots (group 4). The statistical analysis of the mean SCE count per cell was carried out by multiple regression analysis, comparing various predictor variables: exposure group, duration of exposure, age and cigarette consumption. Only cigarette consumption and exposure group were found to be significantly correlated with the mean SCE frequency. After allowing for the effects of smoking, the analysis indicates that: (1) there was no significant difference between group 1 and controls (p > 0.05); (2) the differences between group 2 and group 0, group 3 and group 0 and group 4 and group 0 were all highly significant (p < 0.001); (3) there was no significant difference between groups 2 and 3 (p > 0.05), nor between groups 2 and 3 combined and group 4 (p > 0.05); (4) exposure groups 2, 3 and 4 combined, had a significantly elevated mean SCE frequency compared to the control group (p < 0.0001). Statistical analysis of the proportion of HFCs was consistent with these results. Our data suggest that chronic exposure to whole-body vibration and noise may lead to an increase in the level of SCEs in man. The observed effects may not reflect a direct action of these physical agents on DNA. Alternative explanations may include some of the whole-body vibration and noise-induced or stress-induced pathophysiological alterations which may indirectly induce SCE formation.

An evolutionary perspective on salt, hypertension, and human genetic variability

Natural selection for electrolyte conservation has likely been the norm throughout human evolutionary history. However, the current patterns of excessive dietary salt intake create the potential for salt overload. Under these conditions, hypertension may be considered an expected pathological response to an evolutionarily new constraint. The transatlantic Middle Passage may have created a genetic bottleneck for salt conservation in African-Americans. Although the initial consequences of this important historical event probably constricted genetic variability and further magnified the potential for salt-sensitive hypertension, the Middle Passage undoubtedly also served as a more generalized major source of environmental stress and may have stimulated subsequent hereditary diversity in the survivors of this holocaust and their descendants. Accelerated rates of mutation, genetic recombination, and transposable genetic elements in conjunction with enhanced opportunities for gene flow, new selective pressures, and drift have all contributed to the tremendous heterogeneity of contemporary African-Americans. It is unlikely that a single genetic event, even of the severity of the Middle Passage, can account comprehensively for the apparent susceptibility of this macroethnic group to high blood pressure and hypertension.