The regulatory-adaptive status in the evaluation of human stress-resistance

There was offered a method of human stress-resistance evaluation via the dynamics of the regulatory-adaptive status. The regulatory-adaptive status was being determined via the parameters of the cardiorespiratory synchronism in the original state and at the application of the stress factor. Individuals, whose regulatory-adaptive status didn't change or decreased by not more than 5-6% at the exposition to the stress factor formed the group with a high level of stress-resistance. The individuals, whose regulatory adaptive status at the exposition to the stress factor decreased by less than 50% formed a group with a moderate level of stress-resistance. The examinees, whose regulatory-adaptive status decreased by more than 50% in a response to the stress factor were set in a group with a low stress-resistance level. The method was tested in the three stress models: 1) exam stress-on 58 students; 2) parachute jump stress-on 35 beginner parachutists; 3) stress, caused by the relocation to the zone of the catastrophe on 30 rescuers. In all the three models the method is highly informative. At the same time the levels of the stress-resistance were being evaluated by the psychological methods. It was shown, that the evaluation of the stress-resistance level via the dynamics of the regulatory-adaptive status allows to objectively characterize the ability of an individual to resist stress and should be included in the test complex for the casting of the candidates for the extreme professions.     

Influence of the level of blood pressure on the regulatory-adaptive state

Subjects with an increased blood pressure have a decreased regulatory-adaptive potential. The degree of its decrease increases in individuals with higher blood pressure values. The achievement of the target blood pressure level with antihypertensive drugs normalizes the regulatory-adaptive potential. However, only those patients whose blood pressure values did not exceed 160/90 (systolic/diastolic) mmHg attained the level of adaptation of healthy individuals.     

Individual behavioral and autonomic response to emotional stress in humans

Healthy subjects (n = 53) performed a sound version of the proof-reading test under normal conditions and in the state of emotional stress. Stress resistance was evaluated by the overall number of errors. The propensity to active or passive response to stress was evaluated by the number of "false alarms" and signal omissions. The reaction pattern to emotional stress in stress-resistant subjects, irrespective of their behavioral features, consisted in an increase in sympathetic effects on the cardiac rhythm and a decrease in the reaction time to significant signals. In subjects with low stress resistance, no statistically significant changes in the level of sympathetic tone and reaction time were revealed in the state of stress. Subjects with active behavioral response to stress, irrespective of their level of stress resistance, were characterized by aggressiveness, boldness and independence. Subjects with passive response to stress were inclined to conformism, dependence, and passivity.     

Features of endocrine and cardiovascular response to emotional stress in subjects with different types of temperament

Functional features of endocrine and cardiovascular response to examination stress were investigated in 105 students of the Medical Academy who were divided into three groups according to their temperament types. Subjects with the “Apollon” type of temperament were found to have an adequate response to emotional stress. Subjects with the “Epimetei” type of temperament were characterized by the inert response of the regulatory and effector body systems, which was a prerequisite for the development of endocrine and cardiovascular disturbances. The prevalence of parasympathetic activity in the dynamics of emotional stress in subjects of the “Dionisii” type of temperament is indicative of their resistance to the harmful effect of stress. The preliminary psychological evaluation of the type of temperament makes possible the prognosis of adaptive reactions to stress or dysadaptation.     

Morphologic and Aerodynamic Considerations Regarding the Plumed Seeds of Tragopogon pratensis and Their Implications for Seed Dispersal

Tragopogon pratensis is a small herbaceous plant that uses wind as the dispersal vector for its seeds. The seeds are attached to parachutes that increase the aerodynamic drag force and increase the total distance travelled. Our hypothesis is that evolution has carefully tuned the air permeability of the seeds to operate in the most convenient fluid dynamic regime. To achieve final permeability, the primary and secondary fibres of the pappus have evolved with complex weaving; this maximises the drag force (i.e., the drag coefficient), and the pappus operates in an “optimal” state. We used computational fluid dynamics (CFD) simulations to compute the seed drag coefficient and compare it with data obtained from drop experiments. The permeability of the parachute was estimated from microscope images. Our simulations reveal three flow regimes in which the parachute can operate according to its permeability. These flow regimes impact the stability of the parachute and its drag coefficient. From the permeability measurements and drop experiments, we show how the seeds operate very close to the optimal case. The porosity of the textile appears to be an appropriate solution to achieve a lightweight structure that allows a low terminal velocity, a stable flight and a very efficient parachute for the velocity at which it operates.     

Erythropoietin protects against doxorubicin-induced heart failure

The hormone erythropoietin (EPO) has been demonstrated to have cardioprotective properties. The present study investigates the role of EPO to prevent heart failure following cancer treatment with doxorubicin [adriamycin (AD)]. Male Wistar rats (150 ± 10 g) were treated with saline (vehicle control group); with EPO, subcutaneously at 1,000 IU/kg body wt, three times per week for 4 wk (EPO group); with adriamycin, intraperitoneally at 2.5 mg/kg body wt, three times per week for 2 wk (AD group); and with adriamycin and EPO (EPO-AD group). Echocardiographic measurements showed that EPO-AD treatment prevented the AD-induced decline in cardiac function. Each of the hearts was then exposed to ischemia and reperfusion during Langendorff perfusion. The percentage of recovery after ischemia-reperfusion was significantly greater in EPO-AD than the AD-treated group for left ventricular developed pressure, maximal increase in pressure, and rate pressure product. The level of oxidative stress was significantly higher in AD (5 μM for 24 h)-exposed isolated cardiomyocytes; EPO (5 U/ml for 48 h) treatment prevented this. EPO treatment also decreased AD-induced cardiomyocyte apoptosis, which was associated with the decrease in the Bax-to-Bcl2 ratio and caspase-3 activation. Immunostaining of myocardial tissue for CD31 showed a significant decrease in the number of capillaries in AD-treated animals. EPO-AD treatment restored the number of capillaries. In conclusion, EPO treatment effectively prevented AD-induced heart failure. The protective effect of EPO was associated with a decreased level of oxidative stress and apoptosis in cardiomyocytes as well as improved myocardial angiogenesis.     

Oxidative stress impairs insulin signal in skeletal muscle and causes insulin resistance in postinfarct heart failure

Insulin resistance has been shown to occur as a consequence of heart failure. However, its exact mechanisms in this setting remain unknown. We have previously reported that oxidative stress is enhanced in the skeletal muscle from mice with heart failure after myocardial infarction (MI) (30). This study is aimed to investigate whether insulin resistance in postinfarct heart failure is due to the impairment of insulin signaling in the skeletal muscle caused by oxidative stress. Mice were divided into four groups: sham operated (sham); sham treated with apocynin, an inhibitor of NAD(P)H oxidase activation (10 mmol/l in drinking water); MI; and MI treated with apocynin. After 4 wk, intraperitoneal insulin tolerance tests were performed, and skeletal muscle samples were obtained for insulin signaling measurements. MI mice showed left ventricular dilation and dysfunction by echocardiography and increased left ventricular end-diastolic pressure and lung weight. The decrease in glucose level after insulin load significantly attenuated in MI compared with sham. Insulin-stimulated serine phosphorylation of Akt and glucose transporter-4 translocation were decreased in MI mice by 61 and 23%, respectively. Apocynin ameliorated the increase in oxidative stress and NAD(P)H oxidase activities measured by the lucigenin assay in the skeletal muscle after MI. It also improved insulin resistance and inhibited the decrease of Akt phosphorylation and glucose transporter-4 translocation. Insulin resistance was induced by the direct impairment of insulin signaling in the skeletal muscle from postinfarct heart failure, which was associated with the enhanced oxidative stress via NAD(P)H oxidase.     

Effect of velocity and added resistance on selected coordination and force parameters in front crawl

The effect of (a) increasing velocity and (b) added resistance was examined on the stroke (stroke length, stroke rate [SR]), coordination (index of coordination [IdC], propulsive phases), and force (impulse and peaks) parameters of 7 national-level front crawl swimmers (17.14 ± 2.73 years of swimming; 57.67 ± 1.62 seconds in the 100-m freestyle). The additional resistance was provided by a specially designed parachute. Parachute swimming (PA) and free-swimming (F) conditions were compared at 5 velocities per condition. Video footage was used to calculate the stroke and coordination parameters, and sensors allowed the determination of force parameters. The results showed that (a) an increase in velocity (V) led to increases in SR, IdC, propulsive phase duration, and peak propulsive force (p < 0.05), but no significant change in force impulse per cycle, whatever the condition (PA or F); and (b) in PA conditions, significant increases in the IdC, propulsive phase duration, and force impulse and a decrease in SR were recorded at high velocities (p < 0.05). These results indicated that, in the F condition, swimmers adapted to the change in velocity by modifying stroke and coordination rather than force parameters, whereas the PA condition enhanced the continuity of propulsive action and force development. Added resistance, that is, "parachute training," can be used for specific strength training purposes as long as swimming is performed near maximum velocity.     

Oxidative stress and diabetes: What can we learn about insulin resistance from antioxidant mutant mouse models?

The development of metabolic dysfunctions like diabetes and insulin resistance in mammals is regulated by a myriad of factors. Oxidative stress seems to play a central role in this process as recent evidence shows a general increase in oxidative damage and a decrease in oxidative defense associated with several metabolic diseases. These changes in oxidative stress can be directly correlated with increased fat accumulation, obesity, and consumption of high-calorie/high-fat diets. Modulation of oxidant protection through either genetic mutation or treatment with antioxidants can significantly alter oxidative stress resistance and accumulation of oxidative damage in laboratory rodents. Antioxidant mutant mice have previously been utilized to examine the role of oxidative stress in other disease models, but have been relatively unexplored as models to study the regulation of glucose metabolism. In this review, we will discuss the evidence for oxidative stress as a primary mechanism linking obesity and metabolic disorders and whether alteration of antioxidant status in laboratory rodents can significantly alter the development of insulin resistance or diabetes.     

Antioxidant enzyme activity is up-regulated after unilateral resistance exercise training in older adults

Cellular antioxidant capacity and oxidative stress are postulated to be critical factors in the aging process. The effects of resistance exercise training on the level of skeletal muscle oxidative stress and antioxidant capacity have not previously been examined in older adults. Muscle biopsies from both legs were obtained from the vastus lateralis muscle of 12 men 71 +/- 7 years of age. Subjects then engaged in a progressive resistance exercise-training program with only one leg for 12 weeks. After 12 weeks, the nontraining leg underwent an acute bout of exercise (exercise session identical to that of the trained leg at the same relative intensity) at the same time as the last bout of exercise in the training leg. Muscle biopsies were collected from the vastus lateralis of both legs 48 h after the final exercise bout. Electron transport chain enzyme activity was unaffected by resistance training and acute resistance exercise (p < 0.05). Training resulted in a significant increase in CuZnSOD (pre--7.2 +/- 4.2, post--12.6 +/- 5.6 U.mg protein(-1); p = 0.02) and catalase (pre--8.2 +/- 2.3, post--14.9 +/- 7.6 micromol.min(-1).mg protein(-1); p = 0.02) but not MnSOD activity, whereas acute exercise had no effect on the aforementioned antioxidant enzyme activities. Furthermore, basal muscle total protein carbonyl content did not change as a result of exercise training or acute exercise. In conclusion, unilateral resistance exercise training is effective in enhancing the skeletal muscle cellular antioxidant capacity in older adults. The potential long-term benefits of these adaptations remain to be evaluated.     

Influence of inhibitors of cytoskeleton proteins on water exchange of wheat roots under the after-action of water stress

The dynamics of water molecular state and transport in winter wheat (Triticum aestivum L.) of roots different resistance cultivars was studied by a biophysical method, Nuclear Magnetic Resonance (NMR), and a physiological method, Water-Holding Capacity (WHC). The effective coefficient of water self-diffusion (D(eff)), spin-spin relaxation times (T(2)) and WHC were measured after structural modification of cytoskeleton by colchicine and cytochalasin B after the action of water stress. New information about molecular mechanisms of water state and water transport regulation determined by the influence of dynamic cytoskeleton structure has been obtained. This is very important for the development of a fundamental theory of water exchange in plants, and for the ways of its optimization under conditions of environmental stress.     

Spatial pattern analysis in forest dynamics: deviation from power law and direction of regeneration waves

Grid-based models have been used to understand spatial heterogeneity of the vegetation height in forests and to analyze spatio-temporal dynamics of the forest regeneration process. In this report, we present two methods of identifying lattice models when spatio-temporal data are given. The first method detects directionality of regeneration waves based on the timing of local disturbance events. The second evaluates the forest pattern by recording the fraction of high and low vegetation areas at multiple spatial scales. We illustrate these methods by applying them to patterns generated using three simple stochastic lattice models: (1) two-state model, distinguishing sites with high and low vegetation, (2) three-state model, in which sites can be in an additional disturbed state, and (3) Shimagare model, which considers a continuous range of states. The combination of the two methods provides efficient means of distinguishing the models. The first method has a more direct ecological meaning, while the second is useful when forest data are limited in time.     

Interrelationship between the neocortex and limbic system in emotional stress and epileptiform syndromes

The paper describes bioelectrical correlates of negative emotional states on three models: 1) states caused by local, chronic electric stimulation of negative emotiogenic zones (in cats, rabbits); 2) by a neurogenic stress in rats resulting from a conflict of afferent excitations; 3) by an experimental syndrome--"expectation stress". The data attest that hypersynchronization of bioelectrical activity in limbic and cortical structures is a sufficiently significant correlate of an emotional stress. It is assumed that hypersynchronization reflects one of the general mechanisms of involvement of brain structures in a state of neurogenic stress and its manifestation.     

Oxidative stress as a mechanism of diabetes in diabetic BB prone rats: Effect of secoisolariciresinol diglucoside (SDG)

Secoisolariciresinol diglucoside (SDG) isolated from flaxseed has antioxidant activity and has been shown to prevent hypercholesterolemic atherosclerosis. An investigation was made of the effects of SDG on the development of diabetes in diabetic prone BioBreeding rats (BBdp rats), a model of human type I diabetes [insulin dependent diabetes mellitus (IDDM)] to determine if this type of diabetes is due to oxidative stress and if SDG can prevent the incidence of diabetes. The rats were divided into three groups: Group I, BioBreeding normal rats (BBn rats) (n = 10); group II, BBdp untreated (n = 11); and group III, BBdp treated with SDG 22 mg/kg body wt, orally) (n = 14). Oxidative stress was determined by measuring lipid peroxidation product malondialdehyde (MDA) an index of level of reactive oxygen species in blood and pancreas; and pancreatic chemiluminescence (Pancreatic-CL), a measure of antioxidant reserve. Incidence of diabetes was 72.7% in untreated and 21.4% in SDG-treated group as determined by glycosuria and hyperglycemia. SDG prevented the development of diabetes by approximately 71%. Development of diabetes was associated with an increase in serum and pancreatic MDA and a decrease in antioxidant reserve. Prevention in development of diabetes by SDG was associated with a decrease in serum and pancreatic-MDA and an increase in antioxidant reserve. These results suggest that IDDM is mediated through oxidative stress and that SDG prevents the development of diabetes.     

Long-term dynamics of suspended matter in Naroch lakes: Trend or intervention

The long-term dynamics of suspended matter in the Naroch lakes has been analyzed with the help of autoregressive integrated moving average (ARIMA) models. A comparison of the models showed that, apart from seasonal fluctuations, all Naroch lakes have been affected by dramatic impact, which has resulted in a rapid decrease in absolute values and fluctuation decrease of seston concentration. The models indicate that, in contrast to lakes Naroch and Myastro, the dynamics of the seston concentration in Lake Batorino is characterized by a longer period of stabilization after the impact that occurred in 1991.     

Physiological polymorphism of a population of the common frog. II. The polymorphism of the type of muscle tissue heat resistance in stress]

A study was made of the dynamics in the heat resistance of m. interphalangealis of individual grass frogs under stress. The response of muscle tissue to injury can be differentiated into three types according to the initial heat resistance level: increase, decrease and phase change of the resistance. The pattern of response of muscle tissue of individual frogs to stress is one of manifestationss of physiological polymorphism of the population.     

The Calculation of 3D Solubility Parameters Using Molecular Models

Abstract

In this paper we describe the use of molecular mechanics models to examine detailed intermolecular interactions within the liquid state of a common nonionic surfactant system, nonyl phenol ethoxylate (NPE). Using constant energy molecular dynamics simulations we have studied the relative strengths of dispersive interactions versus polar interactions and have estimated three dimensional solubility parameters for NPE systems as a function of temperature and ethylene oxide content. The predictions at 300 K are in good agreement with three dimensional solubility parameters predicted using group contribution tables. Models of the amorphous liquid state were represented by single molecular structures of NPE in a periodic cell. The solubility parameters predicted with these models were in good agreement with those values derived from models having eight NPE molecules packed into a cell with the exception of the electrostatic interactions, which are the most sensitive to system size effects.     

Characteristic length scales of spatial models in ecology via fluctuation analysis

A technique of fluctuation analysis is introduced for the identification of characteristic length scales in spatial models, with similarities to the recently introduced methods using correlations. The identified length scale provides the optimal size to extract non-trivial large-scale behaviour in such models. The method is demonstrated for three biological models: genetic selection, plant competition and a complex marine system; the first two are coupled map lattices and the last one is a cellular automaton. These cover the three possibilities for asymptotic (long time) dynamics: fixation (the system converges to a fixed point); statistical fixation (the spatial statistics converge to fixed values); and complex statistical structure (the statistics do not converge to fixed values). The technique is shown to have an additional use in the identification of aggregation or dispersal at various scales. The method is rigorously justifiable in the cases when the system under analysis satisfies the FKG (Fortuin-Kasteleyn-Ginibre) property and has a fast decay of correlations. We also discuss the connection between the fluctuation analysis length scale and hydrodynamic limits methods to derive large scale equations for ecological models. <br>     

The relationship of the slope of the heart rate graph regression with linear and nonlinear heart rate dynamics in stationary short-time series

The relationship of the slope of the heart rate graph regression curve (b ₁) with periodic (linear) and nonlinear heart rate dynamics has been studied in stationary short-time series (256 points). For estimating nonlinear dynamics, a parameter derived from correlation dimension has been used, which has made it possible to estimate chaotic processes in short-time series. According to the results of the study, the heart rate dynamics in short-time series may be represented as a sum of linear (periodic) and nonlinear (stochastic) processes. The relationships of b ₁ with both the linear and the nonlinear heart rate dynamics have been demonstrated. Equations for calculating the absolute and relative (to the periodic oscillation amplitude) noises in the heart rate dynamics in short-time series are proposed. Stochastic nonlinear dynamics in different physiological states of humans have been compared. It has been found that the increase in the relative noise intensity in the heart rate dynamics with an increase in respiration rate is determined not only by the decrease in the amplitude of respiratory waves, but also by an increase in the amplitude of the noise itself. The absolute noise intensity is decreased in the states of neurotic excitement, fatigue, and, especially, mental stress. In the state of rest, nonlinear (stochastic) processes dominate over linear (periodic) ones.