Oxidative stress and eicosanoids in the kidneys of hyperglycemic rats treated with dehydroepiandrosterone

Oxidative stress plays a crucial role in the pathogenesis of chronic diabetic complications. Normoglycemic and streptozotocin-diabetic rats were treated with dehydroepiandrosterone (DHEA) (4 mg/d per rat) for 3 weeks. At the end of treatment, hydroxynonenal, hydroperoxyeicosatetraenoic acids and antioxidant levels, as well as Na/K-ATPase activity and membrane fatty acids composition were evaluated in kidney homogenates. Chronic hyperglycemia caused a marked increase of both hydroxynonenal and lipoxygenase pathway products and a drop in both GSH levels and membrane Na/K-ATPase activity. DHEA treatment restored the antioxidant levels to close to the control value and considerably reduced hydroxynonenal and hydroperoxyeicosatetraenoic acid levels. Moreover, DHEA counteracted the detrimental effect of hyperglycemia on membrane function: the drop of Na/K-ATPase activity in diabetic animals was significantly inhibited by DHEA treatment. These results show that DHEA reduces oxidative stress and the consequent increase of lipoxygenase pathway products induced by experimental diabetes in rat kidney; they also suggest that, by reducing the inflammatory response to oxidative stress, DHEA treatment might delay the progression of diabetic kidney disease.     

Invasive house geckos are more willing to use artificial lights than are native geckos

There is increasing concern about the ecological effects of light pollution, as artificial lighting spreads with urban expansion. While artificial lighting can negatively affect some species, others use it in novel ways. In tropical and subtropical regions, artificial lighting has created a novel niche: the ‘night light’ niche. Geckos living as human commensals (house geckos) are apparently well adapted to occupy this niche. In an urban area in north‐eastern Australia, we found that the invasive Asian house gecko Hemidactylus frenatus (Gekkonidae) occupies a broader range of light environments in the field than does the native gecko Gehyra dubia (Gekkonidae). Experimental removal of the invasive species from a building indicated that it did not behaviourally influence the light environments chosen by the native species in the short term; they continued to use darker areas even after the invasive species was removed. In Y‐maze experiments, neither species showed a significant preference for light or dark areas; however, preliminary data suggest the invasive species was more willing to explore the Y‐maze than the native species. The willingness of H. frenatus to forage closer to lights, where insect abundance is typically higher, might account for its success as a global invader of human environments, even in areas where other gecko species are established.     

Fine mapping of genetic variants in BIN1, CLU, CR1 and PICALM for association with cerebrospinal fluid biomarkers for Alzheimer's disease

Recent genome-wide association studies of Alzheimer's disease (AD) have identified variants in BIN1, CLU, CR1 and PICALM that show replicable association with risk for disease. We have thoroughly sampled common variation in these genes, genotyping 355 variants in over 600 individuals for whom measurements of two AD biomarkers, cerebrospinal fluid (CSF) 42 amino acid amyloid beta fragments (Aβ(42)) and tau phosphorylated at threonine 181 (ptau(181)), have been obtained. Association analyses were performed to determine whether variants in BIN1, CLU, CR1 or PICALM are associated with changes in the CSF levels of these biomarkers. Despite adequate power to detect effects as small as a 1.05 fold difference, we have failed to detect evidence for association between SNPs in these genes and CSF Aβ(42) or ptau(181) levels in our sample. Our results suggest that these variants do not affect risk via a mechanism that results in a strong additive effect on CSF levels of Aβ(42) or ptau(181).     

Psychosocial and cognitive function in children with nephrotic syndrome: association with disease and treatment variables

Background

To investigate possible differences in emotional/behavioral problems and cognitive function in children with nephrotic syndrome compared to healthy controls and to examine the effect of disease-specific and steroid treatment-specific characteristics on the abovementioned variables.

Methods

Forty-one patients with nephrotic syndrome (23 boys, age range: 4.4-15.2 years) and 42 sex- and age-matched healthy control subjects (20 boys, age range: 4.1-13.4 years) were enrolled in the study. Disease (severity, age of diagnosis, duration) and steroid treatment (total duration, present methylprednisolone dose and duration of present dose) data were collected. In order to assess children’s emotional/behavioral problems, the Child Behavior Checklist was administered. The Wechsler Intelligence Scale for Children – Third Edition was administered to assess Full-Scale, Verbal, and Performance intelligence quotient (IQ) scores.

Results

The patients presented with more internalizing problems (P?=?0.015), including withdrawal (P?=?0.012) and somatic complaints (P?=?0 .011), but not more anxiety/depression or externalizing problems. A significant association was found between severity of disease and somatic complaints (P?=?0.017) as well as externalizing problems (P?=?0.030). Years of illness were significantly more in those presenting with abnormal anxiety/depression (P?=?0.011). Duration of steroid medication was significantly higher among those presenting with abnormal anxiety/depression (P?=?0.011) and externalizing problems (P?=?0.039). IQ was not associated significantly with disease or steroid treatment variables.

Conclusions

Psychosocial factors and outcomes may be important correlates of children’s nephrotic syndrome and potential targets of thorough assessment and treatment.

     

Subjective Size Perception Depends on Central Visual Cortical Magnification in Human V1

In the Ebbinghaus illusion, the context surrounding an object modulates its subjectively perceived size. Previous work implicates human primary visual cortex (V1) as the neural substrate mediating this contextual effect. Here we studied in healthy adult humans how two different types of context (large or small inducers) in this illusion affected size perception by comparing each to a reference stimulus without any context. We found that individual differences in the magnitudes of the illusion produced by either type of context were correlated with V1 area defined through retinotopic mapping using functional MRI. However, participants'' objective ability to discriminate the size of objects presented in isolation was unrelated to illusion strength and did not correlate with V1 area. Control analyses showed no correlations between behavioral measures and the overall V1 area estimated probabilistically on the basis of neuroanatomy alone. Therefore, subjective size perception correlated with variability in central cortical magnification rather than the anatomical extent of primary visual cortex. We propose that such changes in subjective perception of size are mediated by mechanisms that scale with the extent to which an individual''s V1 selectively represents the central visual field.     

Shielding of relativistic protons

Protons are the most abundant element in the galactic cosmic radiation, and the energy spectrum peaks around 1 GeV. Shielding of relativistic protons is therefore a key problem in the radiation protection strategy of crewmembers involved in long-term missions in deep space. Hydrogen ions were accelerated up to 1 GeV at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, New York. The proton beam was also shielded with thick (about 20 g/cm²) blocks of lucite (PMMA) or aluminium (Al). We found that the dose rate was increased 40–60% by the shielding and decreased as a function of the distance along the axis. Simulations using the General–Purpose Particle and Heavy-Ion Transport code System (PHITS) show that the dose increase is mostly caused by secondary protons emitted by the target. The modified radiation field after the shield has been characterized for its biological effectiveness by measuring chromosomal aberrations in human peripheral blood lymphocytes exposed just behind the shield block, or to the direct beam, in the dose range 0.5–3 Gy. Notwithstanding the increased dose per incident proton, the fraction of aberrant cells at the same dose in the sample position was not significantly modified by the shield. The PHITS code simulations show that, albeit secondary protons are slower than incident nuclei, the LET spectrum is still contained in the low-LET range (<10 keV/μm), which explains the approximately unitary value measured for the relative biological effectiveness.     

Changes in adhesion ability of Aeromonas hydrophila during long exposure to salt stress conditions

Aims

Stressful environmental conditions influence both bacterial growth and expression of virulence factors. In the present study, we evaluated the influence of NaCl on Aeromonas hydrophila adhesiveness at two temperatures. This agent is often involved in clinical cases; however, its pathogenic potential is still not fully understood.

Methods and Results

Bacteria were grown in presence of 1·7%, 3·4%, 6·0% NaCl over a 188 day period and then reinoculated in fresh Nutrient Broth with incubation at 4 and 24°C. Bacterial adhesiveness was tested on Hep‐2 cells, and specimens were processed for light, scanning and transmission electron microscopy. Adhesive capacity decreased over time with an increase in reduction percentages depending on NaCl concentrations. At 1·7% NaCl, the reduction was apparently temporary and adhesiveness rapidly recovered in revitalized bacteria, while 3·4%, 6·0% NaCl seemed to be detrimental. Normal, elongated and filamentous bacteria retained adhesiveness capability, although with reduced expression, while in spherical cells, this property seemed to be lost or dramatically reduced.

Conclusions

Our study shows that high osmolarity plays a significant role in adhesion inhibition, therefore having possible implications in the pathogenesis of the infections by Aer. hydrophila.

Significance and Impact of the Study

This study intends to give a contribution to a better understanding of the pathogenic role of this bacterium whose pathogenicity is still under debate.     

Moving Day and Night: Highly Labile Diel Activity Patterns in a Tropical Snake

Most animals have well established diel activity patterns (e.g., diurnal, crepuscular, or nocturnal), and changes in behavior from diurnal to nocturnal are rare in single species. We radio tracked 50 keelback snakes in a single population, locating them up to four times a day, over five periods of the year in the Australian dry tropics to describe temporal variation in diel movement patterns. Snake body temperatures were also recorded to determine the relationship between activity patterns and body temperatures. Season influenced diel activity patterns significantly. Keelbacks were more likely to move, and moved further in the daytime in the mid‐dry (June–July), and late dry (Aug–Sep) seasons. In the mid‐dry season, 87 percent of movements were diurnal, whereas in the mid‐wet (Feb–March) season, although snakes were much more likely to move, only 43 percent of movements were diurnal. In the late dry season, snakes were slightly more likely to move at night than at any other time of day, and so at this time of the year, snakes could be classified as nocturnal. Thus, overall increased movements in the mid‐wet season (austral summer) were associated with more crepuscular and nocturnal movement. There was a significant relationship between individual snake body temperatures and movement rates in all seasons. Changes in movement patterns may be related to body temperature, and this diurnal species becomes cathemeral in the tropics in summer, when it is possible to maintain high body temperatures both day and night.