Efficiency of flagging and dragging for tick collection

It is acknowledged that data from field studies on tick ecology might be biased by collection methods, but actually comparative studies are still limited. Herein we assessed whether the efficiency of flagging and dragging varies according to tick developmental stage, species, season and habitat. Ticks were collected in three sites bordered by an oak forest. The abundance of ticks collected by each collection method varied according to tick species, developmental stage, season, and habitat. Flagging was in general more efficient in collecting adult ticks, especially in spring and winter. Females were more frequently collected by flagging in the meadow and grassland habitats and males in the man-made trail. Flagging collected significantly more adults of Dermacentor marginatus, Hyalomma marginatum, Haemaphysalis inermis and Ixodes ricinus. Flagging was more efficient in collecting D. marginatus and I. ricinus in spring, and H. inermis and I. ricinus females in both spring and winter. In summer and autumn tick abundances were generally similar, with the exception of D. marginatus female in autumn. Flagging was more efficient in collecting D. marginatus adults in the meadow habitat and in the man-made trail, and I. ricinus adults in the meadow and grassland habitats. Dragging was more efficient in grassland for R. turanicus. Our results suggest that variations in terms of collection method performance are associated to factors linked to tick behaviour, habitat characteristics, and climate. Field studies employing these collection methods should take this into account to avoid misleading conclusions about tick population dynamics and tick-borne pathogen transmission risk.     

A new simple fluorimetric method to assay cytosolic ATP content: application to durum wheat seedlings to assess modulation of mitochondrial potassium channel and uncoupling protein activity under hyperosmotic stress

The assays commonly used to determine ATP content in biological samples generally measure total cellular ATP content, but not the different subcellular pools. In this study a new simple method for measuring ATP content in a cytosol-enriched fraction (CEF) was developed, based on a rapid cytosolic ATP extraction (by an isotonic grinding medium that preserves organelle integrity) and its detection monitoring the NADPH fluorescence generated via hexokinase/glucose-6-phosphate dehydrogenase coupled reactions. Four protocols, differing for timing of NADPH generation and for either the presence or absence of some inhibitors of ATP and NADPH metabolism, were compared by determining CEF-ATP, as well as total ATP, in durum wheat (Triticum durum Desf.) etiolated seedlings. The best protocol was the one adopting both simultaneous NADPH generation and use of inhibitors during tissue homogenization. This protocol also showed higher performance than the classical trichloroacetic acid extraction. Using the new method, CEF-ATP content was assessed in control, salt- and osmotic-stressed seedlings, resulting 2.68 ± 0.04, 1.69 ± 0.12 (?40%) and 1.35 ± 0.16 (?50%) μmol/g dry weight, respectively. Finally, the effects of this stress-dependent decrease of cytosolic ATP were evaluated with respect to a possible modulation of two mitochondrial energy-dissipating systems, the uncoupling protein (PUCP) and the K⁺ channel (PmitoK_ATP), both inhibited by cytosolic ATP. Experiments carried out at different physiological ATP concentrations suggest that the decreased cytosolic ATP content occurring under hyperosmotic stress may contribute to attenuate inhibition of PmitoK_ATP, thus promoting its activity (up to about 90%), but not of PUCP, that appears to lose ATP sensitivity under stress condition.     

Epigallocatechin-3-gallate prevents oxidative phosphorylation deficit and promotes mitochondrial biogenesis in human cells from subjects with Down's syndrome

A critical role for mitochondrial dysfunction has been proposed in the pathogenesis of Down's syndrome (DS), a human multifactorial disorder caused by trisomy of chromosome 21, associated with mental retardation and early neurodegeneration. Previous studies from our group demonstrated in DS cells a decreased capacity of the mitochondrial ATP production system and overproduction of reactive oxygen species (ROS) in mitochondria. In this study we have tested the potential of epigallocatechin-3-gallate (EGCG) – a natural polyphenol component of green tea – to counteract the mitochondrial energy deficit found in DS cells. We found that EGCG, incubated with cultured lymphoblasts and fibroblasts from DS subjects, rescued mitochondrial complex I and ATP synthase catalytic activities, restored oxidative phosphorylation efficiency and counteracted oxidative stress. These effects were associated with EGCG-induced promotion of PKA activity, related to increased cellular levels of cAMP and PKA-dependent phosphorylation of the NDUFS4 subunit of complex I. In addition, EGCG strongly promoted mitochondrial biogenesis in DS cells, as associated with increase in Sirt1-dependent PGC-1α deacetylation, NRF-1 and T-FAM protein levels and mitochondrial DNA content.In conclusion, this study shows that EGCG is a promoting effector of oxidative phosphorylation and mitochondrial biogenesis in DS cells, acting through modulation of the cAMP/PKA- and sirtuin-dependent pathways. EGCG treatment promises thus to be a therapeutic approach to counteract mitochondrial energy deficit and oxidative stress in DS.     

Symptoms and Subjective Quality of Life in Post-Traumatic Stress Disorder: A Longitudinal Study

Background

Evidence suggests that post-traumatic stress disorder (PTSD) is associated with substantially reduced subjective quality of life (SQOL). This study aimed to explore whether and how changes in the levels of PTSD symptom clusters of intrusion, avoidance and hyperarousal are associated with changes in SQOL.

Methods

Two samples with PTSD following the war in former Yugoslavia were studied, i.e. a representative sample of 530 people in five Balkan countries and a non-representative sample of 215 refugees in three Western European countries. They were assessed on average eight years after the war and re-interviewed one year later. PTSD symptoms were assessed on the Impact of Event Scale - Revised and SQOL on the Manchester Short Assessment of Quality of Life. Linear regression and a two-wave cross lagged panel analysis were used to explore the association between PTSD symptom clusters and SQOL.

Results

The findings in the two samples were consistent. Symptom reduction over time was associated with improved SQOL. In multivariable analyses adjusted for the influence of all three clusters, gender and time since war exposure, only changes in hyperarousal symptoms were significantly associated with changes in SQOL. The two-wave cross-lagged panel analysis suggested that the link between hyperarousal symptoms and SQOL is bidirectional.

Conclusions

Low SQOL of patients with war-related PTSD is particularly associated with hyperarousal symptoms. The findings suggest a bidirectional influence: a reduction in hyperarousal symptoms may result in improved SQOL, and improvements in SQOL may lead to reduced hyperarousal symptoms.     

A Structural Overview of the Vertebrate Prion Proteins

Among the diseases caused by protein misfolding is the family associated with the prion protein (PrP). This is a small extracellular membrane-anchored molecule of yet unknown function. Understanding how PrP folds both into its cellular and pathological forms is thought to be crucial for explaining protein misfolding in general and the specific role of PrP in disease. Since the first structure determination, an increasing number of structural studies of PrP have become available, showing that the protein is formed by a flexible N-terminal region and a highly conserved globular C-terminal domain. We review here the current knowledge on PrP structure. We focus on vertebrate PrPs and analyse in detail the similarities and the differences among the coordinates of the C-terminal domain of PrP from different species, in search for understanding the mechanism of disease-causing mutations and the molecular bases of species barrier.Key Words: amyloid, NMR, prion, scrapie, structure, X-ray