The assessment of stress phase objective criteria in humans

The stress reactions phases have been studied in humans in psychoemotional strain. The stress reactions phases objective criteria associated with certain cardiac rhythm variability alterations and cognitive function have been revealed. The study was performed using computerized Stroop-test.     

Scanning molecular sieve chromatography of interacting protein systems. III. Effect of kinetic parameters on the large zone boundary profiles for local equilibration between mobile and stationary phases.

Large zone reaction boundary profiles for molecular sieve chromatography as affected by kinetic parameters have been simulated for local equilibration between the mobile and stationary phases. Our studies of monomer-dimer and monomer-tetramer systems indicate that in a slowly equilibrating system, the kinetic controls operating between the mobile and stationary phases contribute most significantly to the overall boundary profile. In a rapidly equilibrating system, however, the kinetic parameters kij and kji operating in the mobile phase are the principal determinants of the reaction boundary, while the kinetic effects of kii and k-ii between the mobile and stationary phases are minimal.     

Acute Short-Term Mental Stress Does Not Influence Salivary Flow Rate Dynamics

Background: Results of studies that address the influence of stress on salivary flow rate and composition are controversial. The aim of this study was to reveal the influence of stress vulnerability and different phases of stress reactivity on the unstimulated and stimulated salivary flow rate. We examined that acute mental stress does not change the salivary flow rate. In addition, we also examined the salivary cortisol and protein level in relation to acute mental stress stimuli. Methods: Saliva of male subjects was collected for five minutes before, immediately, 10, 30 and 120 min after toothbrushing. Before toothbrushing, the subjects were exposed to acute stress in the form of a 2 min public speech. Salivary flow rate and total protein was measured. The physiological stress marker cortisol was analyzed using enzyme-linked immunosorbent assay. To determine the subjects'' psychological stress reaction, the State-Trait-Anxiety Inventory State questionnaire (STAI) data were obtained. The subjects were divided into stress subgroup (S1) (psychological reactivity), stress subgroup (S2) (psychological and physiological reactivity) and a control group. The area under the curve for salivarycortisol concentration and STAI-State scores were calculated. All data underwent statistical analysis using one-way analysis of variance. Results: Immediately after stress exposure, all participants exhibited a psychological stress reaction. Stress exposure did not change the salivary flow rate. Only 69% of the subjects continued to display a physiological stress reaction 20 minutes after the public talk. There was no significant change in the salivary flow rate during the psychological and the physiological stress reaction phases relative to the baseline. Conclusions: Acute stress has no impact on the salivary flow rate; however, there may be other responses through salivary proteins that are increased with the acute stress stimuli. Future studies are needed to examine specific proteins and their possible roles in acute stress responses.     

Scanning molecular sieve chromatography of interacting protein systems. III. Effect of kinetic parameters on the large zone boundary profiles for local equilibration between mobile and stationary phases

Large zone reaction boundary profiles for molecular sieve chromatography as affected by kinetic parameters have been simulated for local equilibration between the mobile and stationary phases. Our studies of monomer-dimer and monomer-tetramer systems indicate that in a slowly equilibrating system, the kinetic controls operating between the mobile and stationary phases contribute most significantly to the overall boundary profile. In a rapidly equilibrating system, however, the kinetic parameters k(ij) and k(ji) operating in the mobile phase are the principal determinants of the reaction boundary, while the kinetic effects of k(ii) and k-(ii) between the mobile and stationary phases are minimal.     

Analysis of the dynamics of relaxation type oscillation in glycolysis of yeast extracts.

In yeasts, the glycolysis may display oscillations of its metabolites while it is converting glucose. The dynamics of the oscillations has been investigated in cytoplasmic extracts of yeast under relaxation type conditions by determining the time course of some of the glycolytic metabolites. The compounds of the nucleotide pool have been identified as fast variables and the glucose derivatives as slow variables of the relaxation type. The period of oscillation has been subdivided into four phases which represent prominent parts of the limit cycle in the phase plane of a slow versus a fast variable. From the reaction processes in these phases, a dynamical picture of the mechanisms of oscillations is suggested. Accordingly, the oscillation results from an alternating activity of the fructose bisphosphate and the polysaccharide synthesis, both of which are coupled to glycolysis via the nucleotide pool. The processes in the phases are analyzed by calculating the rates of the reaction steps in the biochemical pathway.     

Scanning molecular sieve chromatography of interacting protein systems. Simulation of large zone behavior for self-associating solutes undergoing rapid chemical equilibration under kinetic control

Theoretical large zone reaction boundaries for molecular sieve chromatography have been simulated by computer for a self-associating solute undergoing rapid chemical equilibration under kinetic control. These patterns show that the kinetically-controlled reaction rate between the mobile and stationary phases is the principal determinant of the elution boundary profile in molecular sieve chromatography. The overall chemical reaction rate in the mobile phase was found to have a much greater role in a rapidly equilibrating system than did the effect of axial dispersion within the gel matrix.     

Toxoplasma gondii: cold stress-induced modulation of antibody responses.

Physical or psychological stressors have been shown to have significant consequences in the immune function and the outcome of disease in human and animal models. Recent work has demonstrated that products released during stress, such as glucocorticoids and catecholamines, can profoundly influence the in vitro growth of pathogens by modulating immune responses. The present study examined the effects of a physical stressor (cold stress) on antigens of Toxoplasma gondii that elicits an antibody-mediated immune response during the acute and chronic phases of infection. Sera obtained from different groups of mice subjected to cold stress during the acute and chronic phases of T. gondii infection were used to measure the levels of antibodies and to localize by Western blot the dominant antigens eliciting IgG and IgM antibody responses. Serum antibodies collected from stressed and infected mice recognized antigens different from those recognized by infected mice without stress. During the acute phase, a stronger IgM antibody response against antigens of 30, 42, 54, and 60 kDa was detected in stressed animals at 3 weeks postinfection. In addition, a 5-kDa antigen was specifically detected in mice subjected to stress during the acute and chronic phases of infection. Levels of specific IgG were increased in infected and in infected and stressed animals that underwent stress in the chronic phase. IgM production did not increase following cold stress in the chronic phase. These results suggest that the strong antibody response in stressed animals is associated with longer parasite persistence in circulation. Stress modulated not only the host immune response but also the ability of parasite antigens to elicit specific antibody responses by the host.     

Long-Term and Transgenerational Effects of Stress Experienced during Different Life Phases in Chickens (Gallus gallus)

Stress in animals causes not only immediate reactions, but may affect their biology for long periods, even across generations. Particular interest has been paid to perinatal stress, but also adolescence has been shown to be a sensitive period in mammals. So far, no systematic study has been performed of the relative importance of stress encountered during different life phases. In this study, groups of chickens were exposed to a six-day period of repeated stress during three different life phases: early (two weeks), early puberty (eight weeks) and late puberty (17 weeks), and the effects were compared to an unstressed control group. The short-term effects were assessed by behaviour, and the long-term and transgenerational effects were determined by effects on behavior and corticosterone secretion, as well as on hypothalamic gene expression. Short-term effects were strongest in the two week group and the eight week group, whereas long-term and transgenerational effects were detected in all three stress groups. However, stress at different ages affected different aspects of the biology of the chickens, and it was not possible to determine a particularly sensitive life phase. The results show that stress during puberty appears to be at least equally critical as the previously studied early life phase. These findings may have important implications for animal welfare in egg production, since laying hens are often exposed to stress during the three periods pinpointed here.     

Genetic determination of the response of the mouse hypothalamo-hypophyseo-adrenal system to cold and immobilization stress]

Peculiarities of the hypothalamo-pituitary-adrenal system (HPAS) reaction in mice of 8 inbred strains to a stress effect of the immoblization and of cold have been studied and a comparison of the effect with the reaction of the adrenal cortex to its direct stimulator--ACTH have been carried out. As a result of the study of the resting level of 11-hydroxycorticosteroids in peripheral plasma of inbred mice significant interstrain differences were found. A positive correlation between resting corticosteroids level and the reaction of HPAS to the stress in mouse strains under study was found, but none of them correlated with the reactivity of the adrenal cortex to ACTH.     

Phases of the initial reaction of the sympatho-adrenal system to stress

Changes in the content and ratio of catecholamines, their precursors and metabolites in canine blood and tissues during the initial period of stress have been studied. A sharp increase in tissue adrenaline (A) and dopamine (DA) and a decrease in tissue noradrenaline (NA); decline in blood A and rise in blood NA; inhibition of monoamine oxidase activity and a fall in metanephrine and normetanephrine blood and tissue level have been demonstrated in the first phase of reaction developing right after exposure to stress. A sharp synchronous rise in A, NA and DA and a parallel increase in their metabolic intensity towards oxidative deamination and O-methylation have been found in the second phase of reaction that develops in 60 sec. The first phase of the reaction has been designated as dissociation phase of sympathoadrenal secretory synthetic activity, and the second phase was termed the phase of synchronous system activation.     

Modeling of DNAPL-Dissolution, Rate-Limited Sorption and Biodegradation Reactions in Groundwater Systems

This article presents an approach for modeling the dissolution process of single component dense non-aqueous phase liquids (DNAPL), such as tetrachloroethene and trichloroethene, in a biologically reactive porous medium. In the proposed approach, the overall transport processes are conceptualized as three distinct reactions. Firstly, the dissolution (or dissolving) process of a residual DNAPL source zone is conceptualized as a mass-transfer limited reaction. Secondly, the contaminants dissolved from the DNAPL source are allowed to partition between sediment and water phases through a rate-limited sorption reaction. Finally, the contaminants in the solid and liquid phases are allowed to degrade by a set of kinetic-limited biological reactions. Although all of these three reaction processes have been researched in the past, little progress has been made towards understanding the combined effects of these processes. This work provides a rigorous mathematical model for describing the coupled effects of these three fundamental reactive transport mechanisms. The model equations are then solved using the general-purpose reactive transport code RT3D (Clement, 1997).     

Proton transfer during the reaction between fully reduced cytochrome c oxidase and dioxygen: pH and deuterium isotope effects.

The pH dependence of proton uptake and electron transfers during the reaction between fully reduced cytochrome c oxidase and oxygen has been studied using the flow-flash method. Proton uptake was monitored using different pH indicators. We have also investigated the effect of D2O on the electron-transfer reactions. Proton uptake was biphasic throughout the pH range studied (6.3-9.3), and the decrease of the observed rate constants at increasing pH could be described by titration curves with pKa values of 8-8.5. Of the four phases resolved in the redox reaction, the rate constants for the first two were independent of pH, whereas that of the third decreased at increasing pH with a pKa of 7.9. All phases except the first were slower in D2O than in H2O. The values obtained for kH/kD were 1.0 for the first phase, 1.4 for the second and third phases, and 2.5 for the fourth phase. We suggest from these results that the fast phase of proton uptake is initiated by the second phase of the redox reaction and that this step includes a partially rate-limiting internal proton transfer. The third and fourth phases of the redox reaction are suggested to be rate limited by proton uptake from the medium. The pH dependencies of the proton uptake reactions are consistent with the participation of a titrable group in the protein in proton transfer from the medium to the oxygen-binding site.     

Benzoates of cellulose bonded on silica gel: Chiral discrimination ability as high-performance liquid chromatographic chiral stationary phases

In order to generalize the recently described method for the insolubilization of polysaccharide derivatives to benzoates of cellulose, five mixed 10-undecenoate/benzoates of this polysaccharide have been prepared and linked to allyl silica gel by means of a radical reaction. The chiral recognition ability of the resulting materials when used as high-performance liquid chromatographic chiral stationary phases was evaluated using heptane/2-propanol and heptane/chloroform mixtures as mobile phases. Chirality 9:145–149, 1997. © 1997 Wiley-Liss, Inc.     

Of the importance of metabolic phases in the understanding of oxidative stress in prolonged fasting and refeeding

Life phases such as migration or reproduction may partly (or totally) prohibit food accessibility, making regulation of the energy balance one of the main challenges faced by wild organisms. Although long-term fasting is common in a number of species, it has been reported to be detrimental for the organism, notably because it induces oxidative stress. However, fasting metabolism is characterized by successive metabolic adaptations that are likely to be different in terms of stress, and no previous studies, to our knowledge, have tested the dynamics of changes in oxidative balance in relation to the metabolic phases of fasting. Our study provides a first insight into this relationship by inducing prolonged fasting and subsequent refeeding in captive mallards (Anas platyrhynchos). Both plasmatic antioxidant and oxidative damage levels were observed to be lower during fasting. Oxidative damage levels decreased by 95% during fasting, and they surprisingly remained at low levels even after 3 d of refeeding. In contrast, restoration of the antioxidant barrier was observed from the third day of refeeding onward, and it thus preceded the increase in oxidative damage levels. Therefore, under our experimental conditions, long-term fasting was not associated with marked oxidative stress in mallards. Because data interpretations may be influenced by concomitant metabolic states, we underline the importance of taking metabolic phases into account when studying oxidative stress during fasting.     

Modeling of DNAPL-Dissolution,Rate-Limited Sorption and Biodegradation Reactions in Groundwater Systems

This article presents an approach for modeling the dissolution process of single component dense non-aqueous phase liquids (DNAPL), such as tetrachloroethene and trichloroethene, in a biologically reactive porous medium. In the proposed approach, the overall transport processes are conceptualized as three distinct reactions. Firstly, the dissolution (or dissolving) process of a residual DNAPL source zone is conceptualized as a mass-transfer limited reaction. Secondly, the contaminants dissolved from the DNAPL source are allowed to partition between sediment and water phases through a rate-limited sorption reaction. Finally, the contaminants in the solid and liquid phases are allowed to degrade by a set of kinetic-limited biological reactions. Although all of these three reaction processes have been researched in the past, little progress has been made towards understanding the combined effects of these processes. This work provides a rigorous mathematical model for describing the coupled effects of these three fundamental reactive transport mechanisms. The model equations are then solved using the general-purpose reactive transport code RT3D (Clement, 1997).     

Virus-specific delayed-type hypersensitivity (DTH). Cells mediating lymphocytic choriomeningitis virus-specific DTH reaction in mice

We had previously shown that the local lymphocytic choriomeningitis virus-induced delayed-type hypersensitivity (DTH) reaction in mice consists of two well delineated phases that are mediated by CD8+ and CD4+ T lymphocytes, respectively. These findings have been confirmed and extended by showing that the first CD8+ cell-dependent part of the response was enhanced by either the presence of CD4+ cells or systemic treatment with IL-2 and that it developed in the absence of detectable numbers of mononuclear phagocytes, whereas the later CD4+ cell part required monocytes or related elements. Furthermore, in the DTH reaction that was elicited with noninfectious viral Ag in mice previously immunized by infection, only the CD4+ cells participated. Thus, the two phases of the lymphocytic choriomeningitis-viral DTH reaction are principally different, which has to be taken into account when trying to assess the relevance of DTH during this virus infection.     

Chiral separation of novel iminonaringenin derivatives

A series of 4‐iminonaringenin derivatives 2 ‐ 6 have been prepared in good overall yields from a condensation reaction between naringenin and primary amines. The structures of all products were confirmed by ultraviolet, infrared, proton nuclear magnetic resonance, and carbon‐13 nuclear magnetic resonance spectroscopic techniques. These derivatives were analyzed by high‐performance liquid chromatography using polysaccharide‐based chiral stationary phases, namely, Chiralpak IB and Chiralcel OD, using various mobile phases. 2‐Propanol showed a high enantioselectivity for naringin and its derivatives using achiral column containing immobilized polysaccharides (Chiralpak IB).     

Oxidative stress,spermatogenesis and fertility

Reactive oxygen species production and glutathione depletion in mammalian male germ cells are physiological events that are requisite to the functional maturation and capacitation of spermatozoa. In relation to this oxidative stress, an oxidation of the bulk of protein sulfydryl groups takes place during the final phases of male germ cell maturation. The selenoenzyme phospholipid hydroperoxide glutathione peroxidase catalyzes this reaction, and accounts for both the assembly of the mid-piece of spermatozoa and chromatin condensation. This process highlights the role of H2O2 and selenium in spermatogenesis and provides a mechanism for coupling a 'physiologically controlled' oxidative stress to a specialized phenotypic function.     

The effect of unfavorable environmental factors on the mother-fetus system]

The paper provides a generalization of data and the results of own experiments with Wistar rats in the conditions of hypokinesia, immobilization, water deprivation, hypergravity, weightlessness and other factors affecting mother and fetus as a system. It gives a comparison of reactivity of pregnant and non-pregnant animals under stress, and also of the effects of unfavorable impacts sustained during various phases of ontogenesis: in pubertation period, directly before pregnancy and during various phases of pregnancy. It demonstrated that exposition of pregnant animals to unfavorable conditions is accompanied by significant stress of the compensatory-adaptive possibilities of mother aiming to support of homeostasis of the developing fetus. Clear changes develop in fetus only in case the adaptive possibilities of mother turn out inadequate or when the developing organs of fetus become active components of adaptive reaction of mother-fetus system and compensate for functional inadequacy of some mother's organ. The paper discusses the problem of individual features of resistivity and reactivity.