Anger and posttraumatic stress disorder symptoms in crime victims: A longitudinal analysis

Among trauma-exposed individuals, severity of posttraumatic stress disorder (PTSD) symptoms is strongly correlated with anger. The authors used 2 longitudinal data sets with 282 and 218 crime victims, respectively, to investigate the temporal sequence of anger and PTSD symptoms following the assault. Cross-lagged regression analyses indicated that PTSD symptoms predicted subsequent level of anger, but that anger did not predict subsequent PTSD symptoms. Testing alternative models (common factor model, unmeasured 3rd variable model) that might account for spuriousness of the relation strengthened confidence in the results of the cross-lagged analyses. Further analyses suggested that rumination mediates the effect of PTSD symptoms on anger.

A versatile proline/alanine transporter in the unicellular pathogen Leishmania donovani regulates amino acid homoeostasis and osmotic stress responses

Unlike all other organisms, parasitic protozoa of the family Trypanosomatidae maintain a large cellular pool of proline that, together with the alanine pool, serve as alternative carbon sources as well as reservoirs of organic osmolytes. These reflect adaptation to their insect vectors whose haemolymphs are exceptionally rich in the two amino acids. In the present study we identify and characterize a new neutral amino acid transporter, LdAAP24, that translocates proline and alanine across the Leishmania donovani plasma membrane. This transporter fulfils multiple functions: it is the sole supplier for the intracellular pool of proline and contributes to the alanine pool; it is essential for cell volume regulation after osmotic stress; and it regulates the transport and homoeostasis of glutamate and arginine, none of which are its substrates. Notably, we provide evidence that proline and alanine exhibit different roles in the parasitic response to hypotonic shock; alanine affects swelling, whereas proline influences the rate of volume recovery. On the basis of our data we suggest that LdAAP24 plays a key role in parasite adaptation to its varying environments in host and vector, a phenomenon essential for successful parasitism.

Testosterone and acute stress are associated with fibrinogen and von Willebrand factor in African men: the SABPA study.

BACKGROUND Low testosterone, acute and chronic stress and hypercoagulation are all associated with hypertension and hypertension-related diseases. The interaction between these factors and future risk for coronary artery disease in Africans has not been fully elucidated. In this study, associations of testosterone, acute cardiovascular and coagulation stress responses with fibrinogen and von Willebrand factor in African and Caucasian men in a South African cohort were investigated. METHODS Cardiovascular variables were studied by means of beat-to-beat and ambulatory blood pressure monitoring. Fasting serum-, salivary testosterone and citrate coagulation markers were obtained from venous blood samples. Acute mental stress responses were evoked with the Stroop test. RESULTS The African group demonstrated a higher cardiovascular risk compared to Caucasian men with elevated blood pressure, low-grade inflammation, chronic hyperglycemia (HbA1c), lower testosterone levels, and elevated von Willebrand factor (VWF) and fibrinogen levels. Blunted testosterone acute mental stress responses were demonstrated in African males. In multiple regression analyses, higher circulating levels of fibrinogen and VWF in Africans were associated with a low T environment (R(2) 0.24-0.28; p≤0.01), but only circulating fibrinogen in Caucasians. Regarding endothelial function, a low testosterone environment and a profile of augmented α-adrenergic acute mental stress responses (diastolic BP, D-dimer and testosterone) were associated with circulating VWF levels in Africans (Adj R(2) 0.24; p<0.05). CONCLUSIONS An interdependence between acute mental stress, salivary testosterone, D-dimer and vascular responses existed in African males in their association with circulating VWF but no interdependence of the independent variables occurred with fibrinogen levels.

The effect of acute exercise and psychosocial stress on fine motor skills and testosterone concentration in the saliva of high school students

Little is known about the influence of different stressors on fine motor skills, the concentration of testosterone (T), and their interaction in adolescents. Therefore, 62 high school students aged 14–15 years were randomly assigned to two experimental groups (exercise, psychosocial stress) and a control group. Exercise stress was induced at 65–75% of the maximum heart rate by running for 15 minutes (n = 24). Psychosocial stress was generated by an intelligence test (HAWIK- IV), which was uncontrollable and characterized by social-evaluative-threat to the students (n=21). The control group followed was part of a regular school lesson with the same duration (n = 28). Saliva was collected after a normal school lesson (pre-test) as well as after the intervention/control period (post-test) and was analyzed for testosterone. Fine motor skills were assessed pre- and post-intervention using a manual dexterity test (Flower Trail) from the Movement Assessment Battery for Children-2. A repeated measure ANCOVA including gender as a covariate revealed a significant group by test interaction, indicating an increase in manual dexterity only for the psychosocial stress group. Correlation analysis of all students shows that the change of testosterone from pre- to post-test was directly linked (r = 2.31, p = .01) to the changes in manual dexterity performance. Participants showing high increases in testosterone from pre- to post-test made fewer mistakes in the fine motor skills task. Findings suggest that manual dexterity increases when psychosocial stress is induced and that improvement of manual dexterity performance corresponds with the increase of testosterone.

The role of abscisic acid and water stress in root herbivore-induced leaf resistance

Herbivore-induced systemic resistance occurs in many plants and is commonly assumed to be adaptive. The mechanisms triggered by leaf-herbivores that lead to systemic resistance are largely understood, but it remains unknown how and why root herbivory also increases resistance in leaves. To resolve this, we investigated the mechanism by which the root herbivore Diabrotica virgifera induces resistance against lepidopteran herbivores in the leaves of Zea mays. Diabrotica virgifera infested plants suffered less aboveground herbivory in the field and showed reduced growth of Spodoptera littoralis caterpillars in the laboratory. Root herbivory did not lead to a jasmonate-dependent response in the leaves, but specifically triggered water loss and abscisic acid (ABA) accumulation. The induction of ABA by itself was partly responsible for the induction of leaf defenses, but not for the resistance against S. littoralis. Root-herbivore induced hydraulic changes in the leaves, however, were crucial for the increase in insect resistance. We conclude that the induced leaf resistance after root feeding is the result of hydraulic changes, which reduce the quality of the leaves for chewing herbivores. This finding calls into question whether root-herbivore induced leaf-resistance is an evolved response. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).

Effect of combined drought and heat stress on heat shock proteins in wheat varieties

Introduction: The re sponse of crop plants ex posed on drought or heat shock is related to de crease in the synthesis of normal proteins, accompanied by increased translation of heat shock proteins (HSPs). Though drought and heat stress have been studied individually, little is known about their combined effect on plants. Methods: The wheat (Triticum aestivum L.) varieties (Katya-tolerant, Sadovo or Mladka-susceptible) were potted in soil. Eight-day-old plants were ex posed to with drawing water for seven days. Heat shock was realized in growth chamber at 40 °C for 6h. A combination of drought and heat shock was per formed by subjecting drought-stressed plants to heat shock treatment. Expression of HSPs in the first leaf of wheat varieties was analyzed by SDS electrophoresis and immunoblotting. Polyclonal antibodies against HSP20, HSP60, HSP110 and mononclonal antibodies against HSP70 were used to distinguish the mentioned HSPs. Results: The leaf relative water content (RWC), which indicated the level of plant dehydration decreased significantly (34 %) under drought stressed conditions The electrolyte leakage of ions (EL), representing the level of the cell membrane stability in creased mark edly (68 %), especially under combination of drought and heat. Maximum EL was ob served in drought susceptible varieties Sadovo and Mladka. Drought and heat shock combination in the wheat plants resulted in the induction of specific HSPs. Conclusions: Our results demonstrate that the response of the wheat plants to a combination of drought and heat stress is different from the response of plants to each of these stresses applied separately. Induction of synergetic effect on HSP expression in case of combination between drought and heat was discussed in the case of two contrasting wheat varieties.

Biotic and Abiotic Properties Mediating Plant Diversity Effects on Soil Microbial Communities in an Experimental Grassland

Plant diversity drives changes in the soil microbial community which may result in alterations in ecosystem functions. However, the governing factors between the composition of soil microbial communities and plant diversity are not well understood. We investigated the impact of plant diversity (plant species richness and functional group richness) and plant functional group identity on soil microbial biomass and soil microbial community structure in experimental grassland ecosystems. Total microbial biomass and community structure were determined by phospholipid fatty acid (PLFA) analysis. The diversity gradient covered 1, 2, 4, 8, 16 and 60 plant species and 1, 2, 3 and 4 plant functional groups (grasses, legumes, small herbs and tall herbs). In May 2007, soil samples were taken from experimental plots and from nearby fields and meadows. Beside soil texture, plant species richness was the main driver of soil microbial biomass. Structural equation modeling revealed that the positive plant diversity effect was mainly mediated by higher leaf area index resulting in higher soil moisture in the top soil layer. The fungal-to-bacterial biomass ratio was positively affected by plant functional group richness and negatively by the presence of legumes. Bacteria were more closely related to abiotic differences caused by plant diversity, while fungi were more affected by plant-derived organic matter inputs. We found diverse plant communities promoted faster transition of soil microbial communities typical for arable land towards grassland communities. Although some mechanisms underlying the plant diversity effect on soil microorganisms could be identified, future studies have to determine plant traits shaping soil microbial community structure. We suspect differences in root traits among different plant communities, such as root turnover rates and chemical composition of root exudates, to structure soil microbial communities.

DNA hypomethylation and oxidative stress-mediated increase in genomic instability in equine sarcoid-derived fibroblasts

It is widely accepted that equine sarcoid disease, the most common skin associated neoplasm in equids, is induced by bovine papillomavirus (BPV-1). Although BPV-1 DNA has been found in almost all examined sarcoids so far, its detailed impact on the horse's host cell metabolism is largely unknown. We used equine fibroblast cell lines originating from sarcoid biopsies to study BPV-1-associated changes on DNA methylation status and oxidative stress parameters. Sarcoid-derived fibroblasts manifested increased proliferation in vitro, transcriptional rDNA activity (NORs expression) and DNA hypomethylation compared to control cells. Cells isolated from equine sarcoids suffered from oxidative stress: the expression of antioxidant enzymes was decreased and the superoxide production was increased. Moreover, increased ploidy, oxidative DNA damage and micronuclei formation was monitored in sarcoid cells. We postulate that both altered DNA methylation status and redox milieu may affect genomic stability in BPV-1-infected cells and in turn contribute to sarcoid pathology.

Biotic and abiotic controls of nitrogen and phosphorus cycling in Central European forests

The functioning and services of Central European forests are threatened by global change and a loss of biodiversity. Nutrient cycling as a key forest function is affected by biotic drivers (e.g., dominant tree species, understory plants, soil organisms) that interact with abiotic conditions (e.g., climate, soil properties). In contrast to grassland ecosystems, evidence for the relationship of nutrient cycles and biodiversity in forests is scarce because the structural complexity of forests limits experimental control of driving factors. Alternatively, observational studies along gradients in abiotic conditions and biotic properties may elucidate the role of biodiversity for forest nutrient cycles. This thesis aims to improve the understanding of the functional importance of biodiversity for nutrient cycles in forests by analyzing water-bound fluxes of nitrogen (N) and phosphorus (P) along gradients in biodiversity in three regions of Germany. The tested hypotheses included: (1) temperate forest canopies retain atmospheric N and retention increases with increasing plant diversity, (2) N release from organic layers increases with resource availability and population size of decomposers but N leaching decreases along a gradient in plant diversity, (3) P leaching from forest canopies increases with improved P supply from recalcitrant P fractions by a more diverse ectomycorrhizal fungal community. In the canopies of 27 forest stands from three regions, 16 % to 51 % of atmospheric N inputs were retained. Regional differences in N retention likely resulted from different in N availability in the soil. Canopy N retention was greater in coniferous than in beech forests, but this was not the case on loessderived soils. Nitrogen retention increased with increasing tree and shrub diversity which suggested complementary aboveground N uptake. The strength of the diversity effect on canopy N uptake differed among regions and between coniferous and deciduous forests. The N processing in the canopy directly coupled back to N leaching from organic layers in beech forests because throughfall-derived N flushed almost completely through the mull-type organic layers at the 12 studied beech sites. The N release from organic layers increased with stand basal area but was rather low (< 10 % of annual aboveground litterfall) because of a potentially high microbial N immobilization and intensive incorporation of litter into the mineral soil by bioturbation. Soil fauna biomass stimulated N mineralization through trophic interactions with primary producers and soil microorganisms. Both gross and net leaching from organic layers decreased with increasing plant diversity. Especially the diversity but not the cover of herbs increased N uptake. In contrast to N, P was leached from the canopy. Throughfall-derived P was also flushed quickly through the mull-type organic layers and leached P was predominantly immobilized in non directly plant-available P fractions in the mineral soil. Concentrations of plant-available phosphate in mineral soil solution were low and P leaching from the canopy increased with increasing concentrations of the moderately labile P fraction in soil and increasing ectomycorrhiza diversity while leaf C:P ratios decreased. This suggested that tree P supply benefited from complementary mining of diverse mycorrhizal communities for recalcitrant P. Canopy P leaching increased in years with pronounced spring drought which could lead to a deterioration of P supply by an increasing frequency of drought events. This thesis showed that N and P cycling in Central European forests is controlled by a complex interplay of abiotic site conditions with biological processes mediated by various groups of organisms, and that diverse plant communities contribute to tightening the N cycle in Central European forests and that diverse mycorrhizal communities improve the limited P availability. Maintaining forest biodiversity seems essential to ensure forest services in the light of environmental change.

Increased endothelial microparticles and oxidative stress at extreme altitude.

PURPOSE Hypoxia and oxidative stress affect endothelial function. Endothelial microparticles (MP) are established measures of endothelial dysfunction and influence vascular reactivity. To evaluate the effects of hypoxia and antioxidant supplementation on endothelial MP profiles, a double-blind, placebo-controlled trial, during a high altitude expedition was performed. METHODS 29 participants were randomly assigned to a treatment group (n = 14), receiving vitamin E, C, A, and N-acetylcysteine daily, and a control group (n = 15), receiving placebo. Blood samples were obtained at 490 m (baseline), 3530, 4590, and 6210 m. A sensitive tandem mass spectrometry method was used to measure 8-iso-prostaglandin F2α and hydroxyoctadecadienoic acids as markers of oxidative stress. Assessment of MP profiles including endothelial activation markers (CD62+MP and CD144+MP) and cell apoptosis markers (phosphatidylserine+MP and CD31+MP) was performed using a standardized flow cytometry-based protocol. RESULTS 15 subjects reached all altitudes and were included in the final analysis. Oxidative stress increased significantly at altitude. No statistically significant changes were observed comparing baseline to altitude measurements of phosphatidylserine expressing MP (p = 0.1718) and CD31+MP (p = 0.1305). Compared to baseline measurements, a significant increase in CD62+MP (p = 0.0079) and of CD144+MP was detected (p = 0.0315) at high altitudes. No significant difference in any MP level or oxidative stress markers were found between the treatment and the control group. CONCLUSION Hypobaric hypoxia is associated with increased oxidative stress and induces a significant increase in CD62+ and CD144+MP, whereas phosphatidylserine+MP and CD31+MP remain unchanged. This indicates that endothelial activation rather than an apoptosis is the primary factor of hypoxia induced endothelial dysfunction.

Association of Trait Resilience With Peritraumatic and Posttraumatic Stress in Patients With Myocardial Infarction.

OBJECTIVE Acute myocardial infarction (MI) is a life-threatening condition, leading to immediate fear and distress in many patients. Approximately 18% of patients develop posttraumatic stress disorder in the aftermath of MI. Trait resilience has shown to be a protective factor for the development of posttraumatic stress disorder. However, whether this buffering effect has already an impact on peritraumatic distress and applies to patients with MI is elusive. METHODS We investigated 98 consecutive patients with acute MI within 48 hours after having reached stable circulatory conditions and 3 months thereafter. Peritraumatic distress was assessed retrospectively with three single-item questions about pain, fear, and helplessness during MI. All patients completed the Posttraumatic Diagnostic Scale (PDS) and the Resilience Scale to self-rate posttraumatic stress and trait resilience. RESULTS Multivariate models adjusting for sociodemographic and medical factors showed that trait resilience was not associated with peritraumatic distress, but significantly so with posttraumatic stress. Patients with greater trait resilience showed lower PDS scores (b = -0.06, p < .001). There was no significant relationship between peritraumatic distress scores and PDS scores; resilience did not emerge as a moderator of this relationship. CONCLUSIONS The findings suggest that trait resilience does not buffer the perception of acute MI as stressful per se but may enhance better coping with the traumatic experience in the longer term, thus preventing the development of MI-associated posttraumatic stress. Trait resilience may play an important role in posttraumatic stress symptoms triggered by medical diseases such as acute MI.

Delayed response and lack of habituation in plasma interleukin-6 to acute mental stress in men

Acute mental stress induces a significant increase in plasma interleukin (IL)-6 levels as a possible mechanism for how psychological stress might contribute to atherosclerosis. We investigated whether the IL-6 response would habituate in response to a repetitively applied mental stressor and whether cortisol reactivity would show a relationship with IL-6 reactivity. Study participants were 21 reasonably healthy men (mean age 46+/-7 years) who underwent the Trier Social Stress Test (combination of a 3-min preparation, 5-min speech, and 5-min mental arithmetic) three times with an interval of 1 week. Plasma IL-6 and free salivary cortisol were measured immediately before and after stress, and at 45 and 105 min of recovery from stress. Cortisol samples were also obtained 15 and 30 min after stress. Compared to non-stressed controls, IL-6 significantly increased between rest and 45 min post-stress (p=.022) and between rest and 105 min post-stress (p=.001). Peak cortisol (p=.034) and systolic blood pressure (p=.009) responses to stress both habituated between weeks one and three. No adaptation occurred in diastolic blood pressure, heart rate, and IL-6 responses to stress. The areas under the curve integrating the stress-induced changes in cortisol and IL-6 reactivity were negatively correlated at visit three (r=-.54, p=.011), but not at visit one. The IL-6 response to acute mental stress occurs delayed and shows no adaptation to repeated moderate mental stress. The hypothalamus-pituitary-adrenal axis may attenuate stress reactivity of IL-6. The lack of habituation in IL-6 responses to daily stress could subject at-risk individuals to higher atherosclerotic morbidity and mortality.