1,129 research outputs found

    Modeling the thermal environment in an operating room

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    Comfort is important in everybody's lives, as it is not only a health subject, but also a productive issue. As environmental conditions differ accordingly to the space use, there is a direct influence of this space on human comfort. The Heating Ventilation and Air Conditioning (HVAC) Systems are a crucial way to obtain the expected air quality levels in the interior of buildings and to achieve thermal comfort. These systems ensure air renewal, pressurization, temperature control, and air humidity, being of utmost importance in healthcare facilities. Providing thermal comfort conditions and good air quality, especially in operating rooms, is a difficult task, as the environmental conditions should be suitable for medical staff performance and for patient safety, as well. In the current study, a Computational Fluid Dynamics model was developed and coupled with a thermoregulatory model of the human body to describe the fluid flow, heat transfer and mass transfer between the ventilation air and a human manikin inside an operating room. The CFD simulation solves the heat, mass and momentum conservation equations in the computation domain using a finite volume discretization method, in the ANSYS - environment. The interaction between the body and the environment is determined by the thermoregulatory model, which includes temperature and the moisture diffusion through the cloth fabrics. The combination of the human body and space ventilation models allows evaluating the influence of the main thermal comfort variables on the calculation of comfort index, such as, the PMV

    Reactive Oxygen Species Production and Mitochondrial Dysfunction Contribute to Quercetin Induced Death in Leishmania amazonensis

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    BACKGROUND: Leishmaniasis, a parasitic disease caused by protozoa of the genus Leishmania, affects more than 12 million people worldwide. Quercetin has generated considerable interest as a pharmaceutical compound with a wide range of therapeutic activities. One such activity is exhibited against the bloodstream parasite Trypanosoma brucei and amastigotes of Leishmania donovani. However, the mechanism of protozoan action of quercetin has not been studied. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we report here the mechanism for the antileishmanial activity of quercetin against Leishmania amazonensis promastigotes. Quercetin inhibited L. amazonensis promastigote growth in a dose- and time- dependent manner beginning at 48 hours of treatment and with maximum growth inhibition observed at 96 hours. The IC(50) for quercetin at 48 hours was 31.4 µM. Quercetin increased ROS generation in a dose-dependent manner after 48 hours of treatment. The antioxidant GSH and NAC each significantly reduced quercetin-induced cell death. In addition, quercetin caused mitochondrial dysfunction due to collapse of mitochondrial membrane potential. CONCLUSIONS/SIGNIFICANCE: The effects of several drugs that interfere directly with mitochondrial physiology in parasites such as Leishmania have been described. The unique mitochondrial features of Leishmania make this organelle an ideal drug target while minimizing toxicity. Quercetin has been described as a pro-oxidant, generating ROS which are responsible for cell death in some cancer cells. Mitochondrial membrane potential loss can be brought about by ROS added directly in vitro or induced by chemical agents. Taken together, our results demonstrate that quercetin eventually exerts its antileishmanial effect on L. amazonensis promastigotes due to the generation of ROS and disrupted parasite mitochondrial function

    Effect of bilirubin on cytochrome c oxidase activity of mitochondria from mouse brain and liver

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    <p>Abstract</p> <p>Background</p> <p>The unbound, free concentration (B<sub>f</sub>) of unconjugated bilirubin (UCB), and not the total UCB level, has been shown to correlate with bilirubin cytotoxicity, but the key molecular mechanisms accounting for the toxic effects of UCB are largely unknown.</p> <p>Findings</p> <p>Mouse liver mitochondria increase unbound UCB oxidation, consequently increasing the apparent rate constant for unbound UCB oxidation by HRP (Kp), higher than in control and mouse brain mitochondria, emphasizing the importance of determining Kp in complete systems containing the organelles being studied. The <it>in vitro </it>effects of UCB on cytochrome <it>c </it>oxidase activity in mitochondria isolated from mouse brain and liver were studied at B<sub>f </sub>ranging from 22 to 150 nM. The results show that UCB at B<sub>f </sub>up to 60 nM did not alter mitochondrial cytochrome <it>c </it>oxidase activity, while the higher concentrations significantly inhibited the enzyme activity by 20% in both liver and brain mitochondria.</p> <p>Conclusions</p> <p>We conclude that it is essential to include the organelles being studied in the medium used in measuring both Kp and B<sub>f</sub>. A moderately elevated, pathophysiologically-relevant B<sub>f </sub>impaired the cytochrome <it>c </it>oxidase activity modestly in mitochondria from mouse brain and liver.</p

    Establishing Diagnostic Criteria for Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 3].

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    STUDY DESIGN: Narrative review. OBJECTIVES: To discuss the importance of establishing diagnostic criteria in Degenerative Cervical Myelopathy (DCM), including factors that must be taken into account and challenges that must be overcome in this process. METHODS: Literature review summarising current evidence of establishing diagnostic criteria for DCM. RESULTS: Degenerative Cervical Myelopathy (DCM) is characterised by a degenerative process of the cervical spine resulting in chronic spinal cord dysfunction and subsequent neurological disability. Diagnostic delays lead to progressive neurological decline with associated reduction in quality of life for patients. Surgical decompression may halt neurologic worsening and, in many cases, improves function. Therefore, making a prompt diagnosis of DCM in order to facilitate early surgical intervention is a clinical priority in DCM. CONCLUSION: There are often extensive delays in the diagnosis of DCM. Presently, no single set of diagnostic criteria exists for DCM, making it challenging for clinicians to make the diagnosis. Earlier diagnosis and subsequent specialist referral could lead to improved patient outcomes using existing treatment modalities
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