67 resultados para Beneficial acclimation hypothesis

em BORIS: Bern Open Repository and Information System - Berna - Suiça


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Thermal acclimation is frequently cited as a means by which ectothermic animals improve their Darwinian fitness, i.e. the beneficial acclimation hypothesis. As the critical swimming speed (U (crit)) test is often used as a proxy measure of fitness, we acclimated Atlantic cod (Gadus morhua) to 4 and 10 degrees C and then assessed their U (crit) swimming performance at their respective acclimation temperatures and during acute temperature reversal. Because phenotypic differences exist between different populations of cod, we undertook these experiments in two different populations, North Sea cod and North East Arctic cod. Acclimation to 4 or 10 degrees C had a minimal effect on swimming performance or U (crit), however test temperature did, with all groups having a 10-17% higher U (crit) at 10 degrees C. The swimming efficiency was significantly lower in all groups at 4 degrees C arguably due to the compression of the muscle fibre recruitment order. This also led to a reduction in the duration of "kick and glide" swimming at 4 degrees C. No significant differences were seen between the two populations in any of the measured parameters, due possibly to the extended acclimation period. Our data indicate that acclimation imparts little benefit on U (crit) swimming test in Atlantic cod. Further efforts need to identify the functional consequences of the long-term thermal acclimation process.

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Despite successful intensive care a substantial portion of critically ill patients dies after discharge from the intensive care unit or hospital. Observational studies investigating long-term survival of critically ill patients reported that most deaths occur during the first months or year after discharge. Only limited data on the causes of impaired quality of life and post-intensive care unit deaths exist in the current literature. In this manuscript we hypothesize that the acute inflammatory response which characteristically accompanies critical illness is ensued by a prolonged imbalance or activation of the immune system. Such a chronic low-grade inflammatory response to critical illness may be sub-clinical and persist for a variable period of time after discharge from the intensive care unit and hospital. Chronic inflammation is a well-recognized risk factor for long-term morbidity and mortality, particularly from cardiovascular causes, and may thus partly contribute to the impaired quality of life as well as increased morbidity and mortality following intensive care unit and hospital discharge of critically ill patients. Assuming that critical illness is indeed followed by a prolonged inflammatory response, important implications for treatment would arise. An interesting and potentially beneficial therapy could be the administration of immune-modulating drugs during the time after intensive care unit or hospital discharge until chronic inflammation has subsided. Statins are well-investigated and effective drugs to attenuate chronic inflammation and could potentially also improve long-term outcome of critically ill patients after intensive care unit or hospital discharge. Future studies evaluating the course of inflammation during and after critical illness as well as its response to statin therapy are required.

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Self-Determination Theory (Deci and Ryan in Intrinsic motivation and self-determination in human behavior. Plenum Press, New York, 1985) suggests that certain experiences, such as competence, are equally beneficial to everyone’s well-being (universal hypothesis), whereas Motive Disposition Theory (McClelland in Human motivation. Scott, Foresman, Glenview, IL, 1985) predicts that some people, such as those with a high achievement motive, should benefit particularly from such experiences (matching hypothesis). Existing research on motives as moderators of the relationship between basic need satisfaction and positive outcomes supports both these seemingly inconsistent views. Focusing on the achievement motive, we sought to resolve this inconsistency by considering the specificity of the outcome variables. When predicting domain-specific well-being and flow, the achievement motive should interact with felt competence. However, when it comes to predicting general well-being and flow, felt competence should unfold its effects without being moderated by the achievement motive. Two studies confirmed these assumptions indicating that the universal and matching hypotheses are complementary rather than mutually exclusive.

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Background The goal when resuscitating trauma patients is to achieve adequate tissue perfusion. One parameter of tissue perfusion is tissue oxygen saturation (StO2), as measured by near infrared spectroscopy. Using a commercially available device, we investigated whether clinically relevant blood loss of 500 ml in healthy volunteers can be detected by changes in StO2 after a standardized ischemic event. Methods We performed occlusion of the brachial artery for 3 minutes in 20 healthy female blood donors before and after blood donation. StO2 and total oxygenated tissue hemoglobin (O2Hb) were measured continuously at the thenar eminence. 10 healthy volunteers were assessed in the same way, to examine whether repeated vascular occlusion without blood donation exhibits time dependent effects. Results Blood donation caused a substantial decrease in systolic blood pressure, but did not affect resting StO2 and O2Hb values. No changes were measured in the blood donor group in the reaction to the vascular occlusion test, but in the control group there was an increase in the O2Hb rate of recovery during the reperfusion phase. Conclusion StO2 measured at the thenar eminence seems to be insensitive to blood loss of 500 ml in this setting. Probably blood loss greater than this might lead to detectable changes guiding the treating physician. The exact cut off for detectable changes and the time effect on repeated vascular occlusion tests should be explored further. Until now no such data exist.

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Prolonged postoperative pain and delayed intestinal transit are frequent problems following extended pelvic lymph-node dissection (PLND) and cystectomy.

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Bacterial meningitis in children causes high rates of mortality and morbidity. In a recent clinical trial, oral glycerol significantly reduced severe neurological sequelae in paediatric meningitis caused by Haemophilus influenzae type b, and a tendency towards a benefit of adjunctive glycerol was seen in pneumococcal meningitis.

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This meta-analysis investigated whether the association between researcher allegiance (RA) and the relative effect of two psychotherapies can be explained through the methodological weaknesses of the treatment comparisons. Seventy-nine comparisons of psychotherapies for depression or posttraumatic stress disorder (PTSD) were included. Methodological quality (MQ) was investigated as both a moderator and a mediator of the RA-outcome association. MQ included balanced nonspecific factors, balanced specific factors, conceptual quality, patients-per-therapist ratio, randomization to conditions and outcome assessment. The RA-outcome association was stronger when the MQ was low, suggesting a buffering effect of MQ. In addition, differences in the conceptual quality of treatments mediated the effect of RA on outcome. The results support the view that RA acts as a bias in treatment comparisons.

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Primate multisensory object perception involves distributed brain regions. To investigate the network character of these regions of the human brain, we applied data-driven group spatial independent component analysis (ICA) to a functional magnetic resonance imaging (fMRI) data set acquired during a passive audio-visual (AV) experiment with common object stimuli. We labeled three group-level independent component (IC) maps as auditory (A), visual (V), and AV, based on their spatial layouts and activation time courses. The overlap between these IC maps served as definition of a distributed network of multisensory candidate regions including superior temporal, ventral occipito-temporal, posterior parietal and prefrontal regions. During an independent second fMRI experiment, we explicitly tested their involvement in AV integration. Activations in nine out of these twelve regions met the max-criterion (A < AV > V) for multisensory integration. Comparison of this approach with a general linear model-based region-of-interest definition revealed its complementary value for multisensory neuroimaging. In conclusion, we estimated functional networks of uni- and multisensory functional connectivity from one dataset and validated their functional roles in an independent dataset. These findings demonstrate the particular value of ICA for multisensory neuroimaging research and using independent datasets to test hypotheses generated from a data-driven analysis.