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Nature Communications Jul 2019Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between... (Meta-Analysis)
Meta-Analysis
Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species.
Topics: Acclimatization; Animals; Birds; Climate Change; Phenotype; Selection, Genetic; Time Factors
PubMed: 31337752
DOI: 10.1038/s41467-019-10924-4 -
Journal of Sports Science & Medicine Jun 2019The aim of this meta-analysis was to evaluate the effectiveness of heat acclimatization (HA) on time trial (TT) performance, maximum oxygen uptake (VO), exercise heart... (Meta-Analysis)
Meta-Analysis
The aim of this meta-analysis was to evaluate the effectiveness of heat acclimatization (HA) on time trial (TT) performance, maximum oxygen uptake (VO), exercise heart rate (HR), time trials heart rate (HR), maximal heart rate (HR), core temperature (T), mean skin temperature (T), thermal comfort (T), plasma volume (PV), blood lactate concentration and rate of perceived exertion (RPE). Cochrane-CENTRAL, EMBASE, CINAHL and PubMed databases and reference lists of included studies were searched for randomized controlled trials that investigated the efficacy of HA in athletes. Data were then extracted from the entered studies for analyses. A total of 11 randomised controlled trials (215 participants; mean age, 26.09 years; 91% men) were included after screening of 508 titles and abstracts and 19 full-text articles. The pooled standard mean difference (SMD) between the HA and non-HA groups were 0.50 (95% CI: 0.03 to 0.97, p = 0.04) for TT performance and 1 (95% CI: 1 to 2, p = 0.007) for HR. The pooled mean difference (MD) between the HA and non-HA groups were -7 (95% CI: -13 to -1, p = 0.03) for HR. The changes in T and RPE were too small to be meaningful. There were no significant differences between the HA and non-HA groups for VO, HR, T, T, PV and blood lactate concentration (all p > 0.05). This meta-analysis implies that HA may improve tolerance to discomfort during heat exposure, but may not necessarily improve the associated physiological markers of improved performance.
Topics: Acclimatization; Athletic Performance; Body Temperature; Heart Rate; Hot Temperature; Humans; Lactic Acid; Oxygen Consumption; Plasma Volume; Randomized Controlled Trials as Topic; Skin Temperature
PubMed: 31191102
DOI: No ID Found -
Frontiers in Physiology 2019A majority of high profile international sporting events, including the coming 2020 Tokyo Olympics, are held in warm and humid conditions. When exercising in the heat,...
A majority of high profile international sporting events, including the coming 2020 Tokyo Olympics, are held in warm and humid conditions. When exercising in the heat, the rapid rise of body core temperature ( ) often results in an impairment of exercise capacity and performance. As such, heat mitigation strategies such as aerobic fitness (AF), heat acclimation/acclimatization (HA), pre-exercise cooling (PC) and fluid ingestion (FI) can be introduced to counteract the debilitating effects of heat strain. We performed a meta-analysis to evaluate the effectiveness of these mitigation strategies using magnitude-based inferences. A computer-based literature search was performed up to 24 July 2018 using the electronic databases: PubMed, SPORTDiscus and Google Scholar. After applying a set of inclusion and exclusion criteria, a total of 118 studies were selected for evaluation. Each study was assessed according to the intervention's ability to lower before exercise, attenuate the rise of during exercise, extend at the end of exercise and improve endurance. Weighted averages of Hedges' were calculated for each strategy. PC ( = 1.01) was most effective in lowering before exercise, followed by HA ( = 0.72), AF ( = 0.65), and FI ( = 0.11). FI ( = 0.70) was most effective in attenuating the rate of rise of , followed by HA ( = 0.35), AF ( = -0.03) and PC ( = -0.46). In extending at the end of exercise, AF ( = 1.11) was most influential, followed by HA ( = -0.28), PC ( = -0.29) and FI ( = -0.50). In combination, AF ( = 0.45) was most effective at favorably altering T, followed by HA ( = 0.42), PC ( = 0.11) and FI ( = 0.09). AF (1.01) was also found to be most effective in improving endurance, followed by HA (0.19), FI (-0.16) and PC (-0.20). AF was found to be the most effective in terms of a strategy's ability to favorably alter , followed by HA, PC and lastly, FI. Interestingly, a similar ranking was observed in improving endurance, with AF being the most effective, followed by HA, FI, and PC. Knowledge gained from this meta-analysis will be useful in allowing athletes, coaches and sport scientists to make informed decisions when employing heat mitigation strategies during competitions in hot environments.
PubMed: 30842739
DOI: 10.3389/fphys.2019.00071 -
PloS One 2018The cultivation of bananas and other plants is limited by environmental stresses caused by climate change. In order to recognize physiological, biochemical and molecular...
BACKGROUND
The cultivation of bananas and other plants is limited by environmental stresses caused by climate change. In order to recognize physiological, biochemical and molecular components indicated to confer tolerance to water stress in Musa spp. we present the first systematic review on the topic.
METHODS
A systematic literature review was conducted using four databases for academic research (Google Academic, Springer, CAPES Journal Portal and PubMed Central). In order to avoid publication bias, a previously established protocol and inclusion and exclusion criteria were used.
RESULTS
The drought tolerance response is genotype-dependent, therefore the most studied varieties are constituted by the "B" genome. Tolerant plants are capable of super-expressing genes related to reisistance and defense response, maintaining the osmotic equilibrium and elimination of free radicals. Furthermore, they have higher amounts of water content, chlorophyll levels, stomatic conductance and dry root matter, when compared to susceptible plants.
CONCLUSIONS
In recent years, few integrated studies on the effects of water stress on bananas have been carried out and none related to flood stress. Therefore, we highlight the need for new studies on the mechanisms of differentially expressed proteins in response to stress regulation, post-translational mechanisms and epigenetic inheritance in bananas.
Topics: Acclimatization; Chlorophyll; Droughts; Epigenesis, Genetic; Free Radicals; Gene Expression Regulation, Plant; Musa; Organism Hydration Status; Osmoregulation; Plant Proteins; Plant Stomata; Protein Processing, Post-Translational
PubMed: 30507957
DOI: 10.1371/journal.pone.0208052 -
Global Change Biology Jan 2019Rising atmospheric CO concentration is a key driver of enhanced global greening, thought to account for up to 70% of increased global vegetation in recent decades. CO... (Meta-Analysis)
Meta-Analysis
Rising atmospheric CO concentration is a key driver of enhanced global greening, thought to account for up to 70% of increased global vegetation in recent decades. CO fertilization effects have further profound implications for ecosystems, food security and biosphere-atmosphere feedbacks. However, it is also possible that current trends will not continue, due to ecosystem level constraints and as plants acclimate to future CO concentrations. Future predictions of plant response to rising [CO ] are often validated using single-generation short-term FACE (Free Air CO Enrichment) experiments but whether this accurately represents vegetation response over decades is unclear. The role of transgenerational plasticity and adaptation in the multigenerational response has yet to be elucidated. Here, we propose that naturally occurring high CO springs provide a proxy to quantify the multigenerational and long-term impacts of rising [CO ] in herbaceous and woody species respectively, such that plasticity, transgenerational effects and genetic adaptation can be quantified together in these systems. In this first meta-analysis of responses to elevated [CO ] at natural CO springs, we show that the magnitude and direction of change in eight of nine functional plant traits are consistent between spring and FACE experiments. We found increased photosynthesis (49.8% in spring experiments, comparable to 32.1% in FACE experiments) and leaf starch (58.6% spring, 84.3% FACE), decreased stomatal conductance (g , 27.2% spring, 21.1% FACE), leaf nitrogen content (6.3% spring, 13.3% FACE) and Specific Leaf Area (SLA, 9.7% spring, 6.0% FACE). These findings not only validate the use of these sites for studying multigenerational plant response to elevated [CO ], but additionally suggest that long-term positive photosynthetic response to rising [CO ] are likely to continue as predicted by single-generation exposure FACE experiments.
Topics: Acclimatization; Carbon Dioxide; Ecosystem; Environment; Natural Springs; Photosynthesis; Plant Leaves; Plants
PubMed: 30422366
DOI: 10.1111/gcb.14437 -
Sports Medicine (Auckland, N.Z.) Feb 2018Although the acquisition of heat acclimation (HA) is well-documented, less is known about HA decay (HAD) and heat re-acclimation (HRA). The available literature suggests... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Although the acquisition of heat acclimation (HA) is well-documented, less is known about HA decay (HAD) and heat re-acclimation (HRA). The available literature suggests 1 day of HA is lost following 2 days of HAD. Understanding this relationship has the potential to impact upon the manner in which athletes prepare for major competitions, as a HA regimen may be disruptive during final preparations (i.e., taper).
OBJECTIVE
The aim of this systematic review and meta-analysis was to determine the rate of HAD and HRA in three of the main physiological adaptations occurring during HA: heart rate (HR), core temperature (T ), and sweat rate (SR).
DATA SOURCES
Data for this systematic review were retrieved from Scopus and critical review of the cited references.
STUDY SELECTION
Studies were included when they met the following criteria: HA, HAD, and HRA (when available) were quantified in terms of exposure and duration. HA had to be for at least 5 days and HAD for at least 7 days for longitudinal studies. HR, T , or SR had to be monitored in human participants.
STUDY APPRAISAL
The level of bias in each study was assessed using the McMaster critical review form. Multiple linear regression techniques were used to determine the dependency of HAD in HR, T , and SR from the number of HA and HAD days, daily HA exposure duration, and intensity.
RESULTS
Twelve studies met the criteria and were systematically reviewed. HAD was quantified as a percentage change relative to HA (0% = HA, 100% = unacclimated state). Adaptations in end-exercise HR decreased by 2.3% (P < 0.001) for every day of HAD. For end-exercise T , the daily decrease was 2.6% (P < 0.01). The adaptations in T during the HA period were more sustainable when the daily heat exposure duration was increased and heat exposure intensity decreased. The decay in SR was not related to the number of decay days. However, protracted HA-regimens seem to induce longer-lasting adaptations in SR. High heat exposure intensities during HA seem to evoke more sustained adaptations in SR than lower heat stress. Only eight studies investigated HRA. HRA was 8-12 times faster than HAD at inducing adaptations in HR and T , but no differences could be established for SR.
LIMITATIONS
The available studies lacked standardization in the protocols for HA and HAD.
CONCLUSIONS
HAD and HRA differ considerably between physiological systems. Five or more HA days are sufficient to cause adaptations in HR and T ; however, extending the daily heat exposure duration enhances T adaptations. For every decay day, ~ 2.5% of the adaptations in HR and T are lost. For SR, longer HA periods are related to better adaptations. High heat exposure intensities seem beneficial for adaptations in SR, but not in T . HRA induces adaptations in HR and T at a faster rate than HA. HRA may thus provide a practical and less disruptive means of maintaining and optimizing HA prior to competition.
Topics: Acclimatization; Body Temperature Regulation; Cross-Sectional Studies; Exercise; Heart Rate; Heat Stress Disorders; Hot Temperature; Humans; Male; Oxygen Consumption; Physical Exertion
PubMed: 29129022
DOI: 10.1007/s40279-017-0808-x -
Neonatology 2015The fetal-to-neonatal transition is a complex process that includes changes in cardiac and respiratory systems. (Review)
Review
BACKGROUND
The fetal-to-neonatal transition is a complex process that includes changes in cardiac and respiratory systems.
OBJECTIVE
The aim of this study is to review the different methods of cardiocirculatory monitoring during the immediate neonatal transition period.
METHODS
A systematic search of PubMed and Ovid Embase was performed using the following terms: infant, newborn, newborn infant, neonate, neonates, heart, cardiac, blood pressure, haemodynamic, hemodynamics, blood circulation, circulation, echocardiography, ultrasonography, sonography, electrocardiography, ECG, oximetry, pulse, pulse oximetry, monitoring, measurement, acclimatization, adaptation, transition, after birth and delivery room. Additional articles were identified by manual search of cited references. Only human studies describing cardiocirculatory monitoring during the first 15 min after birth were included.
RESULTS
Thirteen studies were identified that described heart rate (HR). Additional five studies were identified that measured blood pressure. Four studies performed functional echocardiography during neonatal transition; two in addition to blood pressure monitoring and three in addition to HR monitoring.
CONCLUSION
Routine HR monitoring using electrocardiography or pulse oximetry is used to evaluate adequate hemodynamic transition, and reference ranges have been established. Measuring blood pressure noninvasively though noncontinuously might be of some value in future, considering that the normative data have been established recently. Echocardiographic monitoring during the immediate transition period will improve the knowledge about cardiac function changes, but introduction in clinical routine remains questionable.
Topics: Blood Pressure; Echocardiography; Electrocardiography; Female; Heart Function Tests; Heart Rate; Hemodynamics; Humans; Infant, Newborn; Male; Monitoring, Physiologic; Neonatology; Oximetry; Parturition
PubMed: 25412794
DOI: 10.1159/000368042