Damaging Effects Of Stress Research Articles

Nanopore Size Distribution Heterogeneity of Organic-Rich Shale Reservoirs Using Multifractal Analysis and Its Influence on Porosity–Permeability Variation

The shale nanopore size (diameter [less than] 100 nm) distribution heterogeneity (SNDH) is one of the important factors affecting gas production. However, quantitative analysis of the SNDH and the applicability of single and multifractal models need to be further studied. Here, based on low-temperature liquid nitrogen and carbon dioxide tests of organic-rich shale in Qinshui Basin, multifractal dimension variation of micropores ([less than] 2 nm) and mesopores (2–100 nm) are studied, and the multifractal factors that affect the distribution of nanopores are determined. Additionally, the differences between single fractal and multifractal results are compared. Based on this, dynamic variation of porosity and permeability under the constraints of the nanopore structure is discussed from the perspective of multifractal variation. The results of this study are as follows: (1) The pore size distribution of micropores and meso–macropores in shale samples exhibit typical multifractal behavior. The overall distribution heterogeneity of meso–macropores is mainly affected by the distribution of pores in the low-value area of pore volume (LAPV), while the overall distribution heterogeneity of micropores is affected by the distribution of the high-value area of the pore volume. The multifractal parameters and influencing factors of micropores and meso–macropores are clearly different. (2) The single fractal dimension D2 calculated using the Frenkel–Halsey–Hill model has a negative correlation with the multifractal parameters, implying that the distribution heterogeneity of the LAPV gradually decreases with the increase of the D2 value, indicating that the physical meaning of the two models is obviously different. (3) The pore distribution heterogeneity affects permeability variation and diffusion process of shale reservoir. With the increase of the multifractal dimension of meso–macropores, the damaging effect of stress on permeability is stronger. The more heterogeneous the micropore size distribution, the smaller is the ″modification effect″ of stress on the diffusion coefficient.

The effects of a single simultaneous impact of physiotherapeutic factors on stress-realizing and stress-limiting systems of the body

This study is devoted to assessing the effect of a single simultaneous exposure to a low-frequency electrostatic field and transcranial magnetic therapy on non-specific systemic adaptation mechanisms. Objective: to evaluate the effect of a single combined exposure to a low-frequency electrostatic field and transcranial magnetic therapy on the stress-realizing and stress-limiting systems of the human body. Material and methods of research. The study involved 83 male volunteers aged 25 to 38 years (the average age was 31,4±0,33 years), who did not have any chronic diseases and risk factors for their development (the first health group), who were divided into four groups by simple fixed randomization. The first group (control group, 21 people) received placebo treatment (imitation of physiotherapy treatment with the device turned off). In the second group (main group 1, 20 people), the volunteers were singly exposed to transcranial magnetic therapy with traveling magnetic field (TMT TMF) using the device «Amo-Atos» with the attachment «Headband» (RU from 18.11.2011 №FSR 2011/12325). In the third group (main group 2, 21 people), the volunteers were singly exposed to low-frequency electrostatic field (LFESF) using the multifunctional therapeutic system «Khivamat-200» (RU from 12.04.2017 №RZN 2017/5597). To assess the stress-realizing and stress-limiting systems of the body, an analysis of heart rate variability (HRV) was performed, which allows determining the tone of the sympathetic and parasympathetic parts of the autonomic nervous system (ANS). Blood levels of ACTH, cortisol, glucagon, LPO products (malondialdehyde (MDA) and Schiff base (SB)), as well as insulin and the activity of antioxidant enzymes (SOD and catalase) were measured. The study was carried out three times: in the initial state, after 30 minutes, and a day after the end of the single exposure to the complex of physiofactors. The results obtained allow concluding that the criteria for the optimality of a combined single exposure to physiotherapeutic factors is a stable activation of stress-limiting mechanisms against the background of an initial moderate increase and gradual diminishment of stress-realizing manifestations. The dynamics of the estimated indicators observed a day after the exposure indicates the increasing adaptive capabilities of the body to minimize stress-damaging effects. A single simultaneous application of physiotherapy factors demonstrated the possibility of targeted implementation of the strategy of adaptation and control of the severity of physiological, hormonal and metabolic changes within the framework of a non-specific stress response, which opens up new opportunities for optimizing the treatment process.

The role of β-adrenergic receptors in stress-induced cardiac injury in a rat model of Takotsubo syndrome

Introduction. The pathophysiological mechanisms of cardiac injury in Takotsubo syndrome are currently poorly understood. The role of adrenergic receptor (AR) subtypes in the development of stress-induced myocardial injury (SIMI) remains unclear.Aim. To assess the role of β-ARs in the development of SIMI.Material and Methods. The study was performed using female Wistar rats (n = 84). Rats were subject to 24-hour immobilization in the supine position to simulate SIMI. 99mTc-pyrophosphate radiopharmaceutical was used to determine the degree of cardiac injury.Results. The study showed that β-AR blockade with propranolol reduced the degree of cardiac injury by 38.4%. Selective β1- AR antagonists, atenolol and nebivolol, led to 2.00- and 2.55-fold decreases in 99mTc pyrophosphate accumulation in the heart, respectively. Blockade of β2-ARs by a selective antagonist ICI-118.551 caused an increase in the degree of 99mTc-pyrophosphate accumulation in the heart by 34.6%. A selective β3-AR antagonist L-748337 did not affect 99mTc pyrophosphate accumulation in the heart.Conclusions. The study showed that β1-ARs are involved in the damaging effects of stress on the heart during immobilization stress. β2-AR had a cardioprotective effect in immobilization. β3-AP did not play a significant role in the stress-induced cardiac injury with a single exposure to the stressor.

Roles of Calcium and ABA in Alleviating Drought Stress Effects on Triticum aestivum L. Plants

Drought is one of the lethal environmental stress factors that diminish the crop production worldwide. In this study, we assessed the damaging effects of drought stress; imposed by 20% polyethylene glycol (6000) treatments on wheat seedlings, and investigated the possible roles of calcium and abscisic acid (ABA) in alleviating drought stress. The pretreatment of wheat seedlings with calcium and ABA has led to improvements in growth criteria, content of photosynthetic pigments and membrane integrity under drought stress treatment. As a defense mechanism, the activity of peroxidase, and content of proline have increased under drought stress, but deceased when the wheat seedlings have been pretreated with calcium. The application of the calcium channel blocker; lanthanum chloride (LaCl3) has confirmed the alleviating role of calcium to the drought stress damaging effects. In this study, amino acids content, total soluble proteins and carbohydrates have been analyzed to further assess the physiological effects of drought and the alleviating roles of calcium and ABA. The improvements in yield criteria including % of mature grains per spike and weight of grains per spike with calcium pretreatment have confirmed the prolonged effect of calcium in alleviating the damaging effects of drought stress on wheat plants. Taken together, data presented in this study showed that calcium treatment may represent a powerful agent to counterattack the lethal effects of drought stress on plants.

Age-Specific Peculiarities of Modulation of Blood Aldo-Keto Reductase Isoenzyme Spectrum.

The aldo-keto reductase spectrum of the blood was studied at different stages of ontogeny to elucidate the role of reduction pathway in utilization of the carbonyl products of free radical oxidation in modulation of organism sensitivity to the damaging effect of stress during ontogeny. The studies revealed the age-specific changes in aldo-keto reductase spectrum in the blood. An analogy of the aldo-keto reductase spectrum structure in animals of early maturity and in old rats was found. The appearance of age specificity of the aldo-keto reductase spectrum in the blood creates metabolic prerequisites for changes in the efficiency of utilization of carbonyl products of free radical oxidation via their reductive transformation.

Effectiveness of humor on short‐term memory function and cortisol levels in age matched elderly and diabetic subjects vs. control group (684.4)

With ageing, the damaging effects of stress can impair the ability to learn and sustain memory. The purpose was to examine the effect of watching a humor video on short term memory in 3 age matched elderly groups: elderly (69.9 ± 3.7 years), diabetic (67.1 ± 3.8 years), and control (68.7 ± 5.5 years) (no video). Humor and the associated mirthful laughter can reduce stress by decreasing the stress hormone cortisol. Excess cortisol can damage hippocampal neurons leading to impairment of learning and memory. The standardized neuropsychological memory assessment tool, Rey Auditory Verbal Learning Test (RAVLT) was used to assess for 1) learning ability, 2) recall ability, and 3) visual recognition ability. Salivary cortisol measurements, at 3 predetermined time points, were obtained. RAVLT was given to 30 elderly individuals before and after watching a humor video of their choice for 20 minutes vs. no humor video. Results showed that 1) learning ability improved by 38.45% , 33.38%, and 23.96% in the elderly, diabetic, and control groups respectively (p=.025); 2) delayed recall improved by 43.61%, 48.10%, and 20.25% in the elderly, diabetic, and control groups respectively (p=.064); and 3)visual recognition increased by 12.55%, 16.72%, and 8.33% in the elderly, diabetic, and control groups respectively (p=.321). Results, for the changes in salivary cortisol levels, at the predetermined time points, indicated there were 1) borderline significant changes in the elderly group (p=.047, .046, and .062 respectively), 2) significant changes in the diabetic group (p=.047, .025, and .035 respectively), and 3) no changes in the control group (p=.323, .323, and .187 respectively). Due to decreased cortisol levels, elderly and diabetic elderly individuals that watch a humor video that induces mirthful laughter vs. not watching a humor video have greater enhancement in: 1) capability to learn, 2) have greater recall, and 3) improve visual recognition in short term memory function.

Evaluation of the protective effects of tocotrienol-rich fraction from palm oil on the dentate gyrus following chronic restraint stress in rats

Exposure to chronic restraint stress has been shown to cause a number of morphological changes in the hippocampal formation of rats. Tocotrienol, an isoform of vitamin E, exhibits numerous health benefits, different from those of tocopherol. Recent studies have demonstrated that tocotrienol prevents stress-induced changes in the gastric mucosa, thus indicating that it may also protect other organs such as the brain from the damaging effects of stress. Therefore, the aim of the present study was to investigate the protective effect of tocotrienol-rich fraction (TRF) extracted from palm oil on the dentate gyrus of rats following exposure to chronic restraint stress. Thirty-six male Sprague Dawley rats were divided into four groups: control, stress, tocotrienol and combination of stress and tocotrienol. Animals were stressed by restraining them for 5 hours every day for 21 consecutive days. TRF was administered via oral gavage at a dose of 200 mg/kg body weight. Our results showed that the plasma corticosterone level was significantly increased in response to stress, compared to the control. The results confirmed previous findings that chronic restraint stress suppresses cellular proliferation and reduces granule cell number in the dentate gyrus. However, TRF supplementation failed to prevent or minimize these stress-induced changes. Therefore, we conclude that TRF at the current dosage is not effective in preventing the morphological changes in the dentate gyrus induced by chronic restraint stress.

Effectiveness of humor on short term memory function in elderly subjects

With ageing, the damaging effects of stress can impair the ability to learn and sustain memory. The purpose of this pilot study was to examine the effect of watching a humor video on short term memory in the elderly. Humor and the associated mirthful laughter can reduce stress by decreasing stress hormones, cortisol and catecholamines. Excess cortisol can damage hippocampus neurons leading to impairment of learning and memory. The standardized neuropsychological memory assessment tool, Rey Auditory Verbal Learning Test (RAVLT) was used to assess for 1) learning ability, 2) delayed recall ability, and 3) delayed visual recognition ability. RAVLT was given to 10 elderly individuals (average age 74.0 ± 11.7 years) before and after watching a humor video of their choice for 30 minutes. For learning ability, we conducted 5 trials with average performance scores. Results from the Wilcoxon Signed Ranks Test showed that humor with resultant mirthful laughter increased the ability to learn, recall, and recognize. Following the watching of the humor video: 1) learning ability improved by 19.4% (p=.003); 2) delayed recall improved by 33.3% (p=.004); 3) and visual recognition increased by 21.4% (p=.006). In conclusion, elderly individuals’ watching a humor video that induces mirthful laughter can enhance: 1) capability to learn, 2) have greater recall, and 3) improve visual recognition in short term memory function.

Mediation of cognitive function by high fat diet following stress and inflammation

In addition to commonly advertised hazards of obesity contributed by excess dietary fat, evidence of alterations in brain chemistry and structure are well documented. This brief review examines the role of nutrients, minerals and certain lipids, primarily the essential fatty acids (FA), that are beneficial to the maintenance of good health and that may offer therapeutic options by dietary supplementation. The review also considers the damaging effects of stress, especially in pre-existing conditions of obesity and diabetes, as studied in both animals and humans. The main focus of this brief review is to examine the effects of a high fat diet on stress and the immune system with particular emphasis on brain and cognitive function.

Letting the “Gini” out of the bottle: Social causation and the obesity epidemic

Letting the “Gini” out of the bottle: Social causation and the obesity epidemic

Regulation of BDNF and trkB mRNA in rat brain by chronic electroconvulsive seizure and antidepressant drug treatments

The influence of chronic electroconvulsive seizure (ECS) or antidepressant drug treatments on expression of brain-derived neurotrophic factor (BDNF) and its receptor, trkB, was examined by in situ hybridization and Northern blot. In frontal cortex, acute ECS increased BDNF mRNA approximately twofold, an effect significantly augmented by a prior course of chronic ECS treatment (10 d). In the hippocampus, the influence of chronic ECS varied between the major subfields. In the dentate gyrus granule cell layer, chronic ECS decreased the acute induction of BDNF and trkB mRNA by approximately 50%, but prolonged their expression: levels remained elevated two- to threefold 18 hr later after the last chronic ECS treatment, but returned to control 18 hr after acute ECS. In CA3 and CA1 pyramidal cell layers, chronic ECS significantly elevated the acute induction of BDNF, and tended to prolong the expression of BDNF and trkB mRNA. A similar effect was observed in layer 2 of the piriform cortex, where chronic ECS significantly increased the acute induction and prolonged the expression of BDNF and trkB mRNA. Chronic (21 d), but not acute (1 d), administration of several different antidepressant drugs, including tranylcypromine, sertraline, desipramine, or mianserin, significantly increased BDNF mRNA and all but mianserin increased trkB mRNA in hippocampus. In contrast, chronic administration of nonantidepressant psychotropic drugs, including morphine, cocaine, or haloperidol, did not increase levels of BDNF mRNA. Furthermore, chronic administration of ECS or antidepressant drugs completely blocked the down-regulation of BDNF mRNA in the hippocampus in response to restraint stress. The enhanced induction and prolonged expression of BDNF in response to chronic ECS and antidepressant drug treatments could promote neuronal survival, and protect neurons from the damaging effects of stress.