Controlling anoxic tolerance in adult Drosophila via the cGMP-PKG pathway

In this study we identify a cGMP-dependent protein kinase (PKG) cascade as a biochemical pathway critical for controlling low-oxygen tolerance in the adult fruit fly, Drosophila melanogaster. Even though adult Drosophila can survive in 0% oxygen (anoxia) environments for hours, air with less than 2% oxygen rapidly induces locomotory failure resulting in an anoxic coma. We use natural genetic variation and an induced mutation in the foraging (for) gene, which encodes a Drosophila PKG, to demonstrate that the onset of anoxic coma is correlated with PKG activity. Flies that have lower PKG activity demonstrate a significant increase in time to the onset of anoxic coma. Further, in vivo pharmacological manipulations reveal that reducing either PKG or protein phosphatase 2A (PP2A) activity increases tolerance of behavior to acute hypoxic conditions. Alternatively, PKG activation and phosphodiesterase (PDE5/6) inhibition significantly reduce the time to the onset of anoxic coma. By manipulating these targets in paired combinations, we characterized a specific PKG cascade, with upstream and downstream components. Further, using genetic variants of PKG expression/activity subjected to chronic anoxia over 6 h, approximately 50% of animals with higher PKG activity survive, while only approximately 25% of those with lower PKG activity survive after a 24 h recovery. Therefore, in this report we describe the PKG pathway and the differential protection of function vs survival in a critically low oxygen environment.

Withdrawal from methylphenidate increases neural reactivity of dorsal midbrain

Ritalin (methylphenidate hydrochloride, MP) is a non-amphetamine psychostimulant and is the drug of choice to treat children and adults diagnosed with the attention deficit hyperactivity disorder (ADHD). Several studies have demonstrated that rats treated with MP during early developmental stage exhibit alterations in anxiety-related processes such as an increased response to stressful stimuli and elevated plasma levels of corticosterone. Accordingly, the present study was designed to further characterize the neural and behavioral consequences of withdrawal from MP in adult rats and its influence on the neural reactivity of the dorsal midbrain. After initial exposure to an elevated plus-maze (EPM), brainstem neural activation, elicited by exposure to EPM aversive cues, was analyzed using a Fos-protein immunolabeling technique. Additional independent groups of animals were submitted to electrical stimulation of the dorsal column (DPAG) or the startle response procedure, in order to verify the influence of withdrawal from MP on the expression of unconditioned fear induced by DPAG activation and the effects of or withdrawal from MP on motor response, respectively. Our results provide new findings about the influence of MP treatment in adult rats, showing that, after a sudden MP treatment-break, increased anxiety, associated with the neural sensitization of anxiety-related regions, ensues.

Nanofabrication of 30 nm devices incorporating low resistance magnetic tunnel junctions

In this paper the electron-beam lithography conditions and the nanofabrication process are described for current-perpendicular-to-plane (CPP) pillar devices with 30 nm critical dimensions. This work combines a RAITH-150 tool with a negative e-beam resist (AR-7520) so that dense nanopillar arrays are patterned fast into large area samples. The resist dilution and coating conditions are optimized, aiming at its thickness reduction down to 80 nm. The exposure parameters are tuned for different geometries and dimensions, so that features down to 30 nm are exposed with good accuracy (+/- 1.9 nm) and reproducibility. The complete integration of these nanoelements into CPP devices involved electron beam lithography, ion milling for pattern transfer and chemical-mechanical polishing (CMP). Results on devices incorporating very low resistance-area (R x A) MTJ films deposited by Ion beam assisted deposition are shown, for MTJ stacks with R x A down to 0.8 omega x microm2. Device characterization includes electrical measurement of the pillar resistance and the transfer curves under dc magnetic fields (TMR up to 40%).

Normalization strategies for real-time expression data in Chlamydia trachomatis

Chlamydia trachomatis is a widespread obligate intracellular pathogen genetically non-tractable for which transcriptomics is a fundamental tool to better understand its biology. However, the suitability of endogenous controls for normalization of transcriptomic data in this bacterium still needs validation. We aimed to assess the stability of 10 genes for their potential use as endogenous controls in real-time quantitative PCR assays at both normal and stress (D-cycloserine treatment) growth conditions throughout the developmental cycle of three C. trachomatis strains with different tissue tropism. Normalization was performed by real-time absolute quantification of the bacterial genomes. We also tested the applicability of two widely used softwares (geNorm and Normfinder) to our data. For all strains, we found that 16SrRNA was the most stably expressed gene throughout the chlamydial normal developmental cycle, which indicates its potential use as endogenous control in relative expression assays. However, it was highly unstable under D-cycloserine treatment (where oppA_2 was top-ranked), suggesting prudence when using ribosomal genes in expression experiments involving stress conditions. The geNorm and Normfinder algorithms revealed contrasting results and seem inappropriate for the selected pool of genes. Considering the multiplicity of experimental conditions, there should be an in loco validation of endogenous controls, where 16SrRNA appears to be in the front line. Alternatively, normalization of expression data against genomic DNA, which is less influenced by experimental constraints that are especially relevant for intracellular organisms, likely constitutes a good option. Moreover, the number of genomes also seems to be less subject to variation than expression of endogenous controls when working under stress conditions. The present study constitutes the first evaluation of putative endogenous controls for real-time expression assays in C. trachomatis.

[Pulmonary arteriovenous malformations in Rendu-Osler-Weber disease. Case report]

The authors report the clinical case of a 59 year-old woman who was incidentally diagnosed as having arteriovenous pulmonary malformation (AVPM). Through clinical history a diagnosis of Rendu-Osler-Weber disease (ROWD) was made, a disease manifesting itself through the existence of vascular malformations in the skin, mucosae and viscera (like the lungs, liver and brain). The surgical therapy offered to the patient had no complications. The essential aspects of pathofisiology, clinical manifestations and treatment of AVPM and ROWD are discussed.

[Myocardial abscess of the right ventricle anterior wall]

The authors report the clinical case of a 63 old male, with a previous history of aortic mechanical replacement valve, who was admitted with fever, neutrophilic leukocytosis and c-reactive protein elevation. During admission Escherichia coli was cultured from blood, and the patient underwent repeated transthoracic and transesophageal echocardiograms, that did not reveal any abnormalities. Three weeks after admission, a new transesophageal echocardiogram showed an image suggestive of an aortic annular abscess. The patient was transferred to the Cardiothoracic Department of Santa Maria Hospital, in order to be submitted to surgical treatment. During the procedure an abscess in the anterior wall of right ventricle was diagnosed. The microbiological cultures of pus were negative. It was assumed the diagnosis of E. coli myocardial abscess. The diagnostic approach to patients with febrile syndrome and mechanical replacement valve should consider the hypothesis of infectious endocarditis and myocardial abscess, despite the rarity of its occurrence.

Influence of pinholes on MgO-tunnel junction barrier parameters obtained from current-voltage characteristics

Magnetic tunnel junctions (MTJs) with thin barriers are already used as read sensors in recording media. However, the presence of pinholes across such few A thick barriers cannot be excluded and one needs to investigate their effect on the MTJ-transport properties. By applying large electrical currents we could change the electrical resistance of the studied MgO MTJs (due to pinhole-size variations), and study how pinholes influence the barrier parameters (thickness t and height phi) obtained by fitting current-voltage characteristics to Simmons' model. We found that, with decreasing resistance, the barrier thickness (height) decreases (increases). These results were well reproduced by a model of parallel-resistances, allowing us to estimate pinhole-free barrier parameters.

Two approaches to discovering and developing new drugs for Chagas disease

This review will focus on two general approaches carried out at the Sandler Center, University of California, San Francisco, to address the challenge of developing new drugs for the treatment of Chagas disease. The first approach is target-based drug discovery, and two specific targets, cytochrome P450 CYP51 and cruzain (aka cruzipain), are discussed. A 'proof of concept' molecule, the vinyl sulfone inhibitor K777, is now a clinical candidate. The preclinical assessment compliance for filing as an Investigational New Drug with the United States Food and Drug Administration (FDA) is presented, and an outline of potential clinical trials is given. The second approach to identifying new drug leads is parasite phenotypic screens in culture. The development of an assay allowing high throughput screening of Trypanosoma cruzi amastigotes in skeletal muscle cells is presented. This screen has the advantage of not requiring specific strains of parasites, so it could be used with field isolates, drug resistant strains or laboratory strains. It is optimized for robotic liquid handling and has been validated through a screen of a library of FDA-approved drugs identifying 65 hits.

[Minimally invasive thoracic surgery: a fifteen-years experience]

The evolution of surgical techniques has rendering possible for thoracic surgery to be performed efficiently and safely, with less aggressive approaches. Being less traumatic, minimally invasive surgery allows a faster post-operative recovery, less complications and reduces in patient days and morbidity. The authors consider as minimally invasive approaches the video-assisted thoracic surgery, as well as the minithoractomy and the ministernotomy. The present paper reviews thoracic surgeries performed for the last 15 years in a cardiothoracic surgical unit using a minimally invasive surgical approach.

[Intra-thoracic goiter: analysis of the Department's experience]

A review of all clinical files with pre-operative diagnosis of intra-thoracic goiter operated in our Department from 2001-2009 was made. We identified 30 patients, of which 66% were females. 63% of the patients were asymptomatic, 46% had clinical or radiological findings of mediastinal structures compression and 2 patients were ventilated prior to surgery. 50% of the patients were operated on through an inferior transverse cervicotomy, the remaining were operated on through partial or complete sternotomy, with cervical approach. 6,6% of patients (n=2) had an intra-operative diagnosis of invasive thymoma, 3,3% (n=1) had a very invasive mediastinal tumor and 3,3% (n=1) had an ectopic thyroid. Average surgical length of time was of 83 minutes. In 10% of patients (n=3) post-operative invasive ventilation was required, one of which for unilateral permanent lesion of the recurrent laryngeal nerve. In the long term follow-up we assessed 18 patients. The median follow up was 53 months. One patient died at the 15th post-operatory day of pneumonia, one expired at the 30th day for anaplasic thyroid carcinoma progression and one died at the 18 month from invasive thymoma progression. One patient currently reveals evidence of local recurrence 3 patients are currently taking levothyroxine and one is taking propiltiouracil. Pathological studies revealed that 66% of cases were multinodular goiter and neoplasia was present in 13% of the patients. Other results were thymic pathology in 13% of cases (n=4), parathyroid cyst in 3,3% (n=1), and ectopic thyroid in 3,3% (n=1(.

Long lifetimes of quantum-dot intersublevel transitions in the terahertz range

Carrier relaxation is a key issue in determining the efficiency of semiconductor optoelectronic device operation. Devices incorporating semiconductor quantum dots have the potential to overcome many of the limitations of quantum-well-based devices because of the predicted long quantum-dot excited-state lifetimes. For example, the population inversion required for terahertz laser operation in quantum-well-based devices (quantum-cascade lasers) is fundamentally limited by efficient scattering between the laser levels, which form a continuum in the plane of the quantum well. In this context, semiconductor quantum dots are a highly attractive alternative for terahertz devices, because of their intrinsic discrete energy levels. Here, we present the first measurements, and theoretical description, of the intersublevel carrier relaxation in quantum dots for transition energies in the few terahertz range. Long intradot relaxation times (1.5 ns) are found for level separations of 14 meV (3.4 THz), decreasing very strongly to approximately 2 ps at 30 meV (7 THz), in very good agreement with our microscopic theory of the carrier relaxation process. Our studies pave the way for quantum-dot terahertz device development, providing the fundamental knowledge of carrier relaxation times required for optimum device design.

Proatherosclerotic effects of chronic stress in male rats: altered phenylephrine sensitivity and nitric oxide synthase activity of aorta and circulating lipids

The aim of this study was to analyze the effects of chronic mild unpredictable stress (CMS) on the vasoconstrictor response and morphology of the thoracic aorta and serum lipid profiles in rats. Male Sprague-Dawley rats were submitted to CMS, which consisted of the application of different stressors for 7 days per week across 3 weeks. The rats were sacrificed 15 days after CMS exposure. CMS induced supersensitivity to the vasoconstrictor effect of phenylephrine in endothelium-intact thoracic aortic rings without changes in aortic rings without endothelium, or pre-incubated with nitric oxide (NO) synthesis inhibitor. Rats submitted to CMS showed hypertrophy of the intima and tunica media of thoracic aorta, increased serum levels of triglycerides, total cholesterol, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol and atherogenic index, without changes in high-density lipoprotein cholesterol levels, when compared with control rats. These data indicate that CMS induces physiological and morphological changes that may contribute to the development of atherosclerosis by mechanisms related to deficiency in NO production and dyslipidemia.

Physiological, biochemical and functional changes induced by a simulated 30 min off-road competitive motocross heat

AIM

Up to now, few studies regarding the impact of motocross heats on functional and physiological variables have been addressed so far. The aim of the present study was to analyze physiological and functional changes induced by a simulated off-road motocross heat.

METHODS

Fifteen motocross riders (28.3+/-7.9 yrs; 71.1+/-7.0 kg; 169.0+/-4.0 cm; 53.5+/-3.7 mL.kg(-1).min(-1); 14.9+/-3.3% fat) performed one treadmill running to exhaustion to determine maximal heart rate (HRmax) and maximal oxygen consumption. Thereafter, simulated 30 min competitive off-road motocross heats were performed to measure biochemical (blood lactate and urine catecholamine concentrations) and functional (upper-limb power and fatigue--Wingate and Handgrip) alterations induced by the race. Exercise intensity through HR monitoring, rating of perceived exertion and upper-limb pain were also accomplished.

RESULTS

During the 30 min heats, the riders spent 87% of time above 90% of their HRmax. Significant impairments were observed on maximal isometric handgrip as well as on Wingate variables after the race. Blood lactate concentrations significantly increased from rest vs 10 min, 20 min and final time of analysis (P < 0.05). However, a significant decrease was observed between 10 min vs 20 min and final of the race. A significant increase in the 24-h urine catecholamine levels was observed after the race.

CONCLUSION

The present data suggest that motocross heats are performed at high exercise intensity. Motocross specific effort induces significant functional alterations that may reflect muscle fatigue with consequent decrement on physical performance.