733 research outputs found

    Temperature compensation of aerobic capacity and performance in the Antarctic pteropod, \u3cem\u3eClione antarctica\u3c/em\u3e, compared with its northern congener, \u3cem\u3eC. limacina\u3c/em\u3e

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    In ectotherms living in cold waters, locomotory performance is constrained by a slower generation of the ATP that is needed to fuel muscle contraction. Both polar and temperate pteropods of the genus Clione, however, are able to swim continuously by flapping their parapodia (wings) at comparable frequencies at their respective habitat temperatures. Therefore, we expected polar species to have increased aerobic capacities in their wing muscles when measured at common temperatures. We investigated muscle and mitochondrial ultrastructure of Clione antarctica from the Southern Ocean (−1.8°C) and populations of a sister species, Clione limacina, from the Arctic (−0.5 to 3°C) and from the North Atlantic (10°C). We also measured oxygen consumption and the activity of the mitochondrial enzyme citrate synthase (CS) in isolated wings of the two species. The Antarctic species showed a substantial up-regulation of the density of oxidative muscle fibers, but at the expense of fast-twitch muscle fibers. Mitochondrial capacity was also substantially increased in the Antarctic species, with the cristae surface density (58.2±1.3μm2μm−3) more than twice that found in temperate species (34.3±0.8μm2μm−3). Arctic C. limacina was intermediate between these two populations (43.7±0.5μm2μm−3). The values for cold-adapted populations are on par with those found in high-performance vertebrates. As a result of oxidative muscle proliferation, CS activity was 4-fold greater in C. antarctica wings than in temperate C. limacina when measured at a common temperature (20°C). Oxygen consumption of isolated wing preparations was comparable in the two species when measured at their respective habitat temperatures. These findings indicate complete compensation of ATP generation in wing muscles across a 10°C temperature range, which supports similar wing-beat frequencies during locomotion at each species\u27 respective temperature. The elevated capacity in the wing muscles is reflected in the partial compensation of whole-animal oxygen consumption and feeding rates

    Clinical Case Report: Ultrastructural Evidence of Skeletal Muscle Mitochondrial Dysfunction in Patients With Subclinical Hypothyroidism

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    Abstract. Objective: The lack of overt signs and symptoms and controversies surrounding the thyroid stimulating hormone (TSH) reference range variability make the management of subclinical hypothyroidism (sHT) a challenge. Because muscle cramps and weakness have been noted in sHT, histological skeletal muscle examination may be of diagnostic significance as the presence of abnormalities would substantiate a significant consequence of the mild thyroid failure presumed to be present in the individual with sHT. The objective of this study was to investigate the ultrastructural and histological changes of skeletal muscle associated with sHT. Design: Skeletal muscle biopsies from the vastus lateralis were obtained from four subjects with sHT. Samples were fixed, sectioned, and stained for quantitative and qualitative electron and light microscopic analysis. Main Outcome: Analyses revealed characterizable morphological and ultrastructural alterations and quantitative mitochondrial variations between subjects, indicative of skeletal muscle mitochondrial dysfunction in sHT patients. For the 4 subjects, mean mitochondrial perimeter (MP) was 1.09 ± 0.312 ì, mean mitochondrial area (MA) was 0.10 ± 0.05 ì², and mean mitochondrial volume density was 1.92 ± 0.95. Conclusions: The observed and quantified mitochondrial alterations and the noted morphological and ultrastructural alterations identify previously undocumented pathological skeletal muscle alterations associated with sHT. The observed morphological and ultrastructural alterations lend support to a trend of progression of sHT into overt hypothyroidism as a result of mitochondrial dysfunction and associated metabolic shift. The identification of these skeletal muscle alterations as sequelae of sHT may lend convincing objective evidence of a pathophysiologically significant abnormality in patients with sHT. If so, this should diminish the substantial resistance to treatment of these patients at an early stage of disease and attenuate the progression to overt hypothyroidism

    Fast-, Light-Cured Scintillating Plastic for 3D-Printing Applications

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    Additive manufacturing techniques enable a wide range of possibilities for novel radiation detectors spanning simple to highly complex geometries, multi-material composites, and metamaterials that are either impossible or cost prohibitive to produce using conventional methods. The present work identifies a set of promising formulations of photocurable scintillator resins capable of neutron-gamma pulse shape discrimination (PSD) to support the additive manufacturing of fast neutron detectors. The development of these resins utilizes a step-by-step, trial-and-error approach to identify different monomer and cross-linker combinations that meet the requirements for 3D printing followed by a 2-level factorial parameter study to optimize the radiation detection performance, including light yield, PSD, optical clarity, and hardness. The formulations resulted in hard, clear, PSD-capable plastic scintillators that were cured solid within 10 s using 405 nm light. The best-performing scintillator produced a light yield 83% of EJ-276 and a PSD figure of merit equaling 1.28 at 450–550 keVee

    Post-Menopausal Effects of Resistance Training on Muscle Damage and Mitochondria

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    Manfredi, TG, Monteiro, MA, Lamont, LS, Singh, MF, Foldvari, M, White, S, Cosmas, AC, and Urso, ML. Postmenopausal effects of resistance training on muscle damage and mitochondria. J Strength Cond Res 27(2): 556–561, 2013—The purpose of this study was to measure the effects of a 12-month progressive resistance training intervention on muscle morphology and strength gains in postmenopausal women. Skeletal muscle biopsies were obtained from the vastus lateralis of 5 independent community-dwelling women (mean age: 75.6 ± 4.28 years; mean height: 163 ± 5.34 cm; mean weight: 72 ± 17.5 kg) before 6 months and 12 months after progressive resistance training. Muscle strength (1 repetition maximum) was measured at the same time points. After 6 months of training, morphological analysis revealed evidence of increased proteolysis and tissue repair, and rudimentary fiber development. The percent of Z-bands with mild Z-band disruption increased from 43.9% at baseline to 66.7% after 6 months of training (p \u3c 0.01). Mitochondrial volume also increased (percent of mitochondria = 0.86% at baseline, 1.19% at 6 months, and 1.04% at 12 months, p \u3c 0.05), and there was a shift to larger sized mitochondria. The training did not result in statistically significant increases in muscle leg strength (p \u3c 0.18). It appears that mild Z-band disruption acts as a precursor for increased protein synthesis and stimulates an increase in mitochondrial mass. Therefore, although a progressive resistance training program in this population did not increase muscle strength, it did demonstrate clinical applications that lend support to the importance of resistance training in older adults

    Effect of Fuel Ethanol Content on Exhaust Emissions of a Flexible Fuel Vehicle

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    The European Union is aiming at increasing the market share of biofuels in order to improve the security of supply of transport fuel and to reduce CO2 emissions. The target is to reach a 10% of biofuels on energy basis in the transport sector by 2020. Bioethanol and biodiesel represent the only biofuels currently available on the market in big quantities and technologically mature and bioethanol is probably the most widely use alternative fuel in the world (mainly in Brazil and in the USA). According to the literature, the success of bioethanol as alternative fuel is linked to some clear advantages but there are also disadvantages: Advantages: - Very high octane number - As a renewable fuel produces lower CO2 emissions compare to conventional fuels - It reduces some pollutant emissions - Its ozone forming potential is lower than that of gasoline and diesel - It contains no sulphur and is biodegradable Disadvantages: - It increases evaporative emissions (when blended with gasoline at low percentages) - Because of the lower vapour pressure and high latent heat of vaporization of neat ethanol, it makes cold start in cooler climates more difficult. - It increase acetaldehyde emissions but reduces those of formaldehyde. - E85 vehicles give higher unregulated emissions (ethane and acetaldehyde) than gasoline fuelled vehicles. Due to its characteristics neat ethanol cannot be used as transport fuel mainly because its high heat of vaporization and low volatility make cold start very difficult especially in cold climates. The most common way to overcome this problem is to blend ethanol with a small fraction of a much more volatile fuel such as gasoline; the most popular blend is E85 which consists of 85% ethanol and 15% gasoline by volume. Although E85 has been extensively used worldwide, engine manufacturers guarantee problem-free operation without any modification only to catalyst equipped cars fuelled with gasoline containing no more than 5% ethanol. However modern catalyst-equipped cars are probably able to run without any material problem with up to 20% ethanol which seems to be the upper limit for cold climates. An experimental activity has been planned and carried out at the JRC to investigate the emissions of a flexible fuel vehicle using different ethanol/gasoline blends. The results of this experimental programme are briefly summarized here below. The details of the work and the complete results are described in the first part of this document ( In particular, three different fuels have been tested: a standard commercial summer gasoline marketed in Italy used as base fuel and two gasoline/ethanol blends, which have been obtained by splash blending ethanol in the standard gasoline. The two gasoline/ethanol blends contained respectively 10% ethanol (E10) and 85% ethanol (E85). The test vehicle was a passenger car currently marketed in Europe and one of the most popular models belonging to the flexible fuel vehicle category. Emission tests were carried out both following the European certification procedure (NEDC cycle) and using a US driving cycle (US 06). Regulated and unregulated emissions were measured.JRC.H.4-Transport and air qualit

    VA residential substance use disorder treatment program providers’ perceptions of facilitators and barriers to performance on pre-admission processes

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    Abstract Background In the U.S. Department of Veterans Affairs (VA), residential treatment programs are an important part of the continuum of care for patients with a substance use disorder (SUD). However, a limited number of program-specific measures to identify quality gaps in SUD residential programs exist. This study aimed to: (1) Develop metrics for two pre-admission processes: Wait Time and Engagement While Waiting, and (2) Interview program management and staff about program structures and processes that may contribute to performance on these metrics. The first aim sought to supplement the VA’s existing facility-level performance metrics with SUD program-level metrics in order to identify high-value targets for quality improvement. The second aim recognized that not all key processes are reflected in the administrative data, and even when they are, new insight may be gained from viewing these data in the context of day-to-day clinical practice. Methods VA administrative data from fiscal year 2012 were used to calculate pre-admission metrics for 97 programs (63 SUD Residential Rehabilitation Treatment Programs (SUD RRTPs); 34 Mental Health Residential Rehabilitation Treatment Programs (MH RRTPs) with a SUD track). Interviews were then conducted with management and front-line staff to learn what factors may have contributed to high or low performance, relative to the national average for their program type. We hypothesized that speaking directly to residential program staff may reveal innovative practices, areas for improvement, and factors that may explain system-wide variability in performance. Results Average wait time for admission was 16 days (SUD RRTPs: 17 days; MH RRTPs with a SUD track: 11 days), with 60% of Veterans waiting longer than 7 days. For these Veterans, engagement while waiting occurred in an average of 54% of the waiting weeks (range 3–100% across programs). Fifty-nine interviews representing 44 programs revealed factors perceived to potentially impact performance in these domains. Efficient screening processes, effective patient flow, and available beds were perceived to facilitate shorter wait times, while lack of beds, poor staffing levels, and lengths of stay of existing patients were thought to lengthen wait times. Accessible outpatient services, strong patient outreach, and strong encouragement of pre-admission outpatient treatment emerged as facilitators of engagement while waiting; poor staffing levels, socioeconomic barriers, and low patient motivation were viewed as barriers. Conclusions Metrics for pre-admission processes can be helpful for monitoring residential SUD treatment programs. Interviewing program management and staff about drivers of performance metrics can play a complementary role by identifying innovative and other strong practices, as well as high-value targets for quality improvement. Key facilitators of high-performing facilities may offer programs with lower performance useful strategies to improve specific pre-admission processes

    Phage Paride can kill dormant, antibiotic-tolerant cells of Pseudomonas aeruginosa by direct lytic replication

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    Bacteriophages are ubiquitous viral predators that have primarily been studied using fast-growing laboratory cultures of their bacterial hosts. However, microbial life in nature is mostly in a slow- or non-growing, dormant state. Here, we show that diverse phages can infect deep-dormant bacteria and suspend their replication until the host resuscitates ("hibernation"). However, a newly isolated Pseudomonas aeruginosa phage, named Paride, can directly replicate and induce the lysis of deep-dormant hosts. While non-growing bacteria are notoriously tolerant to antibiotic drugs, the combination with Paride enables the carbapenem meropenem to eradicate deep-dormant cultures in vitro and to reduce a resilient bacterial infection of a tissue cage implant in mice. Our work might inspire new treatments for persistent bacterial infections and, more broadly, highlights two viral strategies to infect dormant bacteria (hibernation and direct replication) that will guide future studies on phage-host interactions

    A Forward semi-Lagrangian Method for the Numerical Solution of the Vlasov Equation

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    This work deals with the numerical solution of the Vlasov equation. This equation gives a kinetic description of the evolution of a plasma, and is coupled with Poisson's equation for the computation of the self-consistent electric field. The coupled model is non linear. A new semi-Lagrangian method, based on forward integration of the characteristics, is developed. The distribution function is updated on an eulerian grid, and the pseudo-particles located on the mesh's nodes follow the characteristics of the equation forward for one time step, and are deposited on the 16 nearest nodes. This is an explicit way of solving the Vlasov equation on a grid of the phase space, which makes it easier to develop high order time schemes than the backward method

    The course of traumatic pancreatitis in a patient with pancreas divisum: a case report

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    BACKGROUND: The peculiar anatomy of pancreatic ducts in pancreas divisum (PD) may interfere with the development of acute chronic pancreatitis. In the presented case, PD influenced the evolution of lesions after pancreatic trauma. CASE PRESENTATION: A 38 years old patient refferred to our hospital with recurrent episodes of mild pancreatitis during the last two years. The first episode occurred four months after blunt abdominal trauma. Endoscopic Retrograde Cholangiopancreatography, Magnetic Resonance Imaging of upper abdomen and Magnetic Resonance Cholangiopancreatography disclosed pancreas divisum, changes consistent with chronic pancreatitis in the dorsal pancreatic duct, atrophy in the body and tail of the pancreas and a pseudocyst in the pancreatic head, that was drained endoscopically. CONCLUSION: Pancreas Divisum may interfere with the evolution of posttraumatic changes in the pancreas after blunt abdominal trauma
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