scholarly journals No sex differences in adult telomere length across vertebrates: a meta-analysis

2020 ◽  
Vol 7 (11) ◽  
pp. 200548
Author(s):  
Florentin Remot ◽  
Victor Ronget ◽  
Hannah Froy ◽  
Benjamin Rey ◽  
Jean-Michel Gaillard ◽  
...  
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Telomere Length ◽  
Meta Analysis ◽  
Mammalian Species ◽  
Reptile Species ◽  
Negative Effect ◽  
Males And Females ◽  
Heterogametic Sex ◽  
Meta Analyses

In many mammalian species, females live on average longer than males. In humans, women have consistently longer telomeres than men, and this has led to speculation that sex differences in telomere length (TL) could play a role in sex differences in longevity. To address the generality and drivers of patterns of sex differences in TL across vertebrates, we performed meta-analyses across 51 species. We tested two main evolutionary hypotheses proposed to explain sex differences in TL, namely the heterogametic sex disadvantage and the sexual selection hypotheses. We found no support for consistent sex differences in TL between males and females among mammal, bird, fish and reptile species. This absence of sex differences in TL across different classes of vertebrates does not support the heterogametic sex disadvantage hypothesis. Likewise, the absence of any negative effect of sexual size dimorphism on male TL suggests that sexual selection is not likely to mediate the magnitude of sex differences in TL across vertebrates. Finally, the comparative analyses we conducted did not detect any association between sex differences in TL and sex differences in longevity, which does not support the idea that sex differences in TL could explain the observed sex differences in longevity.

scholarly journals Does testosterone affect lateralization of brain and behaviour? A meta-analysis in humans and other animal species

2008 ◽  
Vol 364 (1519) ◽  
pp. 929-942 ◽  
Author(s):  
Kristina A Pfannkuche ◽  
Anke Bouma ◽  
Ton G.G Groothuis
Keyword(s):  
Sex Differences ◽  
Animal Species ◽  
Meta Analysis ◽  
Mammalian Species ◽  
Experimental Studies ◽  
Fundamental Principle ◽  
Sufficient Information ◽  
Visuospatial Cognition ◽  
Organizational Effects ◽  
Meta Analyses

Lateralization of brain and behaviour has been the topic of research for many years in neuropsychology, but the factors guiding its development remain elusive. Based on sex differences in human lateralization, four hypotheses have been postulated that suggest a role for androgens, specifically testosterone. With the discovery that lateralization is a fundamental principle in the organization of brain and behaviour among vertebrates, it has now become possible to experimentally test such hypotheses in animal models. The use of different taxa, humans, other mammalian species and birds (with oestradiol and not testosterone involved in sexual differentiation in birds) facilitates to differentiate between the hypotheses. We used meta-analyses for analysing papers that provided sufficient information, and a semi-quantitative approach based on all relevant studies that we extracted from the literature. We tested the predictions of these hypotheses regarding strength and direction of lateralization for motor output, language and visuospatial cognition in these three taxa. We tested for sex differences and early organizational effects of testosterone (both correlative and experimental studies). We found sex differences in the direction of lateralization for non-human mammals (motor biases similar to humans) and in direction and strength in birds (visual cognitive tasks). However, the prediction that prenatal testosterone exposure affects the direction of lateralization was not supported for humans. In birds and non-human mammals, opposite trends were found, with the effect in non-human mammals being opposite to the expectation based on sex differences. None of the four hypotheses was sufficiently supported and more studies, testing a wider array of functions in different taxa while reporting the data more completely are needed.

scholarly journals Sex Differences in Exercise-Induced Bronchoconstriction in Athletes: A Systematic Review and Meta-Analysis

2020 ◽  
Vol 17 (19) ◽  
pp. 7270
Author(s):  
Daniel Enrique Rodriguez Bauza ◽  
Patricia Silveyra
Keyword(s):  
Sex Differences ◽  
Female Athletes ◽  
Meta Analysis ◽  
Sexually Dimorphic ◽  
Atopic Status ◽  
Management Plans ◽  
Disease Experience ◽  
Males And Females ◽  
Male Sex ◽  
Exercise Induced

Exercise-induced bronchoconstriction (EIB) is a common complication of athletes and individuals who exercise regularly. It is estimated that about 90% of patients with underlying asthma (a sexually dimorphic disease) experience EIB; however, sex differences in EIB have not been studied extensively. With the goal of better understanding the prevalence of EIB in males and females, and because atopy has been reported to occur at higher rates in athletes, in this study, we investigated sex differences in EIB and atopy in athletes. A systematic literature review identified 60 studies evaluating EIB and/or atopy in post-pubertal adult athletes (n = 7501). Collectively, these studies reported: (1) a 23% prevalence of EIB in athletes; (2) a higher prevalence of atopy in male vs. female athletes; (3) a higher prevalence of atopy in athletes with EIB; (4) a significantly higher rate of atopic EIB in male vs. female athletes. Our analysis indicates that the physiological changes that occur during exercise may differentially affect male and female athletes, and suggest an interaction between male sex, exercise, and atopic status in the course of EIB. Understanding these sex differences is important to provide personalized management plans to athletes with underlying asthma and/or atopy.

scholarly journals Biomarkers of environmental manganese exposure and associations with childhood neurodevelopment: a systematic review and meta-analysis

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Weiwei Liu ◽  
Yongjuan Xin ◽  
Qianwen Li ◽  
Yanna Shang ◽  
Zhiguang Ping ◽  
...  
Keyword(s):  
Sex Differences ◽  
Motor Skills ◽  
Meta Analysis ◽  
Fold Increase ◽  
Behavioral Performance ◽  
Cross Sectional ◽  
Manganese Exposure ◽  
Negative Effect ◽  
The Mean ◽  
Cross Sectional Studies

Abstract Background Although prior studies showed a correlation between environmental manganese (Mn) exposure and neurodevelopmental disorders in children, the results have been inconclusive. There has yet been no consistent biomarker of environmental Mn exposure. Here, we summarized studies that investigated associations between manganese in biomarkers and childhood neurodevelopment and suggest a reliable biomarker. Methods We searched PubMed and Web of Science for potentially relevant articles published until December 31th 2019 in English. We also conducted a meta-analysis to quantify the effects of manganese exposure on Intelligence Quotient (IQ) and the correlations of manganese in different indicators. Results Of 1754 citations identified, 55 studies with 13,388 subjects were included. Evidence from cohort studies found that higher manganese exposure had a negative effect on neurodevelopment, mostly influencing cognitive and motor skills in children under 6 years of age, as indicated by various metrics. Results from cross-sectional studies revealed that elevated Mn in hair (H-Mn) and drinking water (W-Mn), but not blood (B-Mn) or teeth (T-Mn), were associated with poorer cognitive and behavioral performance in children aged 6–18 years old. Of these cross-sectional studies, most papers reported that the mean of H-Mn was more than 0.55 μg/g. The meta-analysis concerning H-Mn suggested that a 10-fold increase in hair manganese was associated with a decrease of 2.51 points (95% confidence interval (CI), − 4.58, − 0.45) in Full Scale IQ, while the meta-analysis of B-Mn and W-Mn generated no such significant effects. The pooled correlation analysis revealed that H-Mn showed a more consistent correlation with W-Mn than B-Mn. Results regarding sex differences of manganese associations were inconsistent, although the preliminary meta-analysis found that higher W-Mn was associated with better Performance IQ only in boys, at a relatively low water manganese concentrations (most below 50 μg/L). Conclusions Higher manganese exposure is adversely associated with childhood neurodevelopment. Hair is the most reliable indicator of manganese exposure for children at 6–18 years of age. Analysis of the publications demonstrated sex differences in neurodevelopment upon manganese exposure, although a clear pattern has not yet been elucidated for this facet of our study.

scholarly journals Sex differences in lizard escape decisions vary with latitude, but not sexual dimorphism

2015 ◽  
Vol 282 (1805) ◽  
pp. 20150050 ◽  
Author(s):  
Diogo S. M. Samia ◽  
Anders Pape Møller ◽  
Daniel T. Blumstein ◽  
Theodore Stankowich ◽  
William E. Cooper
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Risk Taking ◽  
Reproductive Effort ◽  
Meta Analysis ◽  
Specific Behaviour ◽  
Underlying Mechanisms ◽  
Natural And Sexual Selection ◽  
Predator Behaviour ◽  
Latitudinal Effect

Sexual selection is a powerful evolutionary mechanism that has shaped the physiology, behaviour and morphology of the sexes to the extent that it can reduce viability while promoting traits that enhance reproductive success. Predation is one of the underlying mechanisms accounting for viability costs of sexual displays. Therefore, we should expect that individuals of the two sexes adjust their anti-predator behaviour in response to changes in predation risk. We conducted a meta-analysis of 28 studies (42 species) of sex differences in risk-taking behaviour in lizards and tested whether these differences could be explained by sexual dichromatism, by sexual size dimorphism or by latitude. Latitude was the best predictor of the interspecific heterogeneity in sex-specific behaviour. Males did not change their escape behaviour with latitude, whereas females had increasingly reduced wariness at higher latitudes. We hypothesize that this sex difference in risk-taking behaviour is linked to sex-specific environmental constraints that more strongly affect the reproductive effort of females than males. This novel latitudinal effect on sex-specific anti-predator behaviour has important implications for responses to climate change and for the relative roles of natural and sexual selection in different species.

scholarly journals Does sexual selection explain human sex differences in aggression?

2009 ◽  
Vol 32 (3-4) ◽  
pp. 249-266 ◽  
Author(s):  
John Archer
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Physical Aggression ◽  
Role Theory ◽  
Social Roles ◽  
Social Role ◽  
Conflicts Of Interest ◽  
Reproductive Competition ◽  
Threat Displays ◽  
Males And Females

AbstractI argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent with an alternative life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained.

Association between shortened telomere length and systemic lupus erythematosus: a meta-analysis

Lupus ◽  
2016 ◽  
Vol 26 (3) ◽  
pp. 282-288 ◽  
Author(s):  
Y H Lee ◽  
J H Jung ◽  
Y H Seo ◽  
J-H Kim ◽  
S J Choi ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Telomere Length ◽  
Lupus Erythematosus ◽  
Meta Analysis ◽  
Data Type ◽  
Assay Method ◽  
Control Group ◽  
Sample Type ◽  
Systemic Lupus ◽  
Meta Analyses

Objective We aimed to evaluate the relationship between telomere length and systemic lupus erythematosus (SLE). Methods PUBMED and EMBASE databases were searched; meta-analyses were performed comparing telomere length in SLE patients and healthy controls, and on SLE patients in subgroups based on ethnicity, sample type, assay method and data type. Results Eight studies including 472 SLE patients and 365 controls were ultimately selected which showed that telomere length was significantly shorter in the SLE group than in the control group (standardized mean difference (SMD) = −0.835, 95% confidence interval (CI) = −1.291 to −0.380, p = 3.3 × 10−4). Stratification by ethnicity showed significantly shortened telomere length in the SLE group in Caucasian, Asian and mixed populations (SMD = −0.455, 95% CI = −0.763 to −0.147, p = 0.004; SMD = −0.887, 95% CI = −1.261 to −0.513, p = 3.4 × 10−4; SMD = −0.535, 95% CI = −0.923 to −0.147, p = 0.007; respectively). Furthermore, telomere length was significantly shorter in the SLE group than in the control group in whole blood and peripheral blood mononuclear cell groups (SMD = −0.361, 95% CI = −0.553 to −0.169, p = 2.3 × 10−4; SMD = −1.546, 95% CI = −2.583 to −0.510, p = 0.003; respectively); a similar trend was observed in leukocyte groups (SMD = −0.699, 95% CI = −1.511 to −0.114, p = 0.092). Meta-analyses based on assay method or data type revealed similar associations. Conclusions Our meta-analysis demonstrated that telomere length was significantly shorter in patients with SLE, regardless of ethnicity, sample type or assay method evaluated.

scholarly journals Telomere length analysis from minimally-invasively collected samples: methods development and meta-analysis of the validity of different sampling techniques

2019 ◽  
Author(s):  
Peter H Rej ◽  
Madison Bondy ◽  
Jue Lin ◽  
Aric Prather ◽  
Brandon Kohrt ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Telomere Length ◽  
Meta Analysis ◽  
External Validation ◽  
Dried Blood Spots ◽  
Sampling Techniques ◽  
Methods Development ◽  
Meta Analyses ◽  
Length Analysis

Objectives: Telomeres are the protective caps of chromosomes. They shorten with cell replication, age, and possibly environmental stimuli (e.g., infection and stress). Short telomere length (TL) predicts subsequent worse health. Although venous whole blood (VWB) is most commonly used for TL measurement, other, more minimally-invasive, sampling techniques are becoming increasingly common due to their field-friendliness, allowing for feasible measurement in low-resource contexts. We conducted validation work for measuring TL in dried blood spots (DBS) and incorporated our results into a meta-analysis evaluating minimally-invasive sampling techniques to measure TL.Methods: We isolated DNA extracts from DBS using a modified extraction protocol and tested how they endured different shipping conditions and long-term cryostorage. We then included our in-house DBS TL validation statistics (correlation values with VWB TL and age) in a series of meta-analyses of results from 24 other studies that published similar associations for values between TL measured in DBS, saliva, and buccal cells (BC). Results: Our modified DBS extraction technique produced DNA yields that were roughly twice as large as previously recorded. Partially extracted DBS DNA was stable for seven days at room temperature, and still provided reliable TL measurements, as determined by external validation statistics. In our meta-analysis, DBS TL had the highest external validity (i.e., strongest overall association with both VWB TL and age), followed by saliva, and then BC. Conclusions: Measuring TL using DNA isolated from DBS is the best option for minimally-invasively collected samples, which can be used to expand research to diverse settings and populations.

scholarly journals Sex Differences in Presentation of Stroke: A Systematic Review and Meta-Analysis

Stroke ◽  
2021 ◽  
Author(s):  
Mariam Ali ◽  
Hendrikus J.A. van Os ◽  
Nelleke van der Weerd ◽  
Jan W. Schoones ◽  
Martijn W. Heymans ◽  
...  
Keyword(s):  
Systematic Review ◽  
Sex Differences ◽  
Acute Stroke ◽  
Transient Ischemic Attack ◽  
Controlled Trial ◽  
Meta Analysis ◽  
Neurological Symptoms ◽  
Cross Sectional ◽  
Ischemic Attack ◽  
Meta Analyses

Background and Purpose: Women have worse outcomes than men after stroke. Differences in presentation may lead to misdiagnosis and, in part, explain these disparities. We investigated whether there are sex differences in clinical presentation of acute stroke or transient ischemic attack. Methods: We conducted a systematic review and meta-analysis according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Inclusion criteria were (1) cohort, cross-sectional, case-control, or randomized controlled trial design; (2) admission for (suspicion of) ischemic or hemorrhagic stroke or transient ischemic attack; and (3) comparisons possible between sexes in ≥1 nonfocal or focal acute stroke symptom(s). A random-effects model was used for our analyses. We performed sensitivity and subanalyses to help explain heterogeneity and used the Newcastle-Ottawa Scale to assess bias. Results: We included 60 studies (n=582 844; 50% women). In women, headache (pooled odds ratio [OR], 1.24 [95% CI, 1.11–1.39]; I 2 =75.2%; 30 studies) occurred more frequently than in men with any type of stroke, as well as changes in consciousness/mental status (OR, 1.38 [95% CI, 1.19–1.61]; I 2 =95.0%; 17 studies) and coma/stupor (OR, 1.39 [95% CI, 1.25–1.55]; I 2 =27.0%; 13 studies). Aspecific or other neurological symptoms (nonrotatory dizziness and non-neurological symptoms) occurred less frequently in women (OR, 0.96 [95% CI, 0.94–0.97]; I 2 =0.1%; 5 studies). Overall, the presence of focal symptoms was not associated with sex (pooled OR, 1.03) although dysarthria (OR, 1.14 [95% CI, 1.04–1.24]; I 2 =48.6%; 11 studies) and vertigo (OR, 1.23 [95% CI, 1.13–1.34]; I 2 =44.0%; 8 studies) occurred more frequently, whereas symptoms of paresis/hemiparesis (OR, 0.73 [95% CI, 0.54–0.97]; I 2 =72.6%; 7 studies) and focal visual disturbances (OR, 0.83 [95% CI, 0.70–0.99]; I 2 =62.8%; 16 studies) occurred less frequently in women compared with men with any type of stroke. Most studies contained possible sources of bias. Conclusions: There may be substantive differences in nonfocal and focal stroke symptoms between men and women presenting with acute stroke or transient ischemic attack, but sufficiently high-quality studies are lacking. More studies are needed to address this because sex differences in presentation may lead to misdiagnosis and undertreatment.

scholarly journals Sex differences in patients with COVID-19: a retrospective cohort study and meta-analysis

2020 ◽  
Vol 8 (T1) ◽  
pp. 574-597
Author(s):  
Zhijun Li ◽  
Lina Feng ◽  
Wenyu Cui ◽  
Jian Zhang ◽  
Yingxin Huang ◽  
...  
Keyword(s):  
Sex Differences ◽  
Northeast China ◽  
Older Patients ◽  
Retrospective Cohort ◽  
Clinical Characteristics ◽  
Web Of Science ◽  
Meta Analysis ◽  
Cochrane Library ◽  
Fatality Rate ◽  
Meta Analyses

BACKGROUND: Accumulated evidence revealed that male was much more likely to higher severity and fatality by SARS-CoV-2 infection than female patients, but few studies and meta-analyses have evaluated the sex differences of the infection and progression of COVID-19 patients. AIM: We aimed to compare the sex differences of the epidemiological and clinical characteristics in COVID-19 patients; and to perform a meta-analysis evaluating the severe rate, fatality rate, and the sex differences of the infection and disease progression in COVID-19 patients. METHODS: We analyzed clinical data of patients in Changchun Infectious Hospital and Center, Changchun, Northeast China; and searched PubMed, Embase, Web of Science, and Cochrane Library without any language restrictions for published articles that reported the data of sex-disaggregated, number of severe, and death patients on the confirmed diagnosis of adult COVID-19 patients. RESULTS: The pooled severe rate and fatality rate of COVID-19 were 22.7% and 10.7%. Male incidence in the retrospective study was 58.1%, and the pooled incidence in male was 54.7%. CONCLUSION: The pooled severe rate in male and female of COVID-19 was 28.2% and 18.8%, the risky of severe and death was about 1.6folds higher in male compared with female, especially for older patients (> 50 y).

The Sexual Brain

2021 ◽  
pp. 81-108
Author(s):  
Susan D. Healy
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Brain Size ◽  
Female Mate Choice ◽  
Brain Regions ◽  
Good Evidence ◽  
The Other ◽  
Female Mate ◽  
Males And Females ◽  
Hippocampal Structure

Morphological and behavioural differences between the sexes are ubiquitous across the animal kingdom. There is also good evidence for differences in some brain regions between males and females, in humans, some rodents, and many songbirds. I look at the data for sex differences in cognition, of which there are some that show differences in spatial cognition and in hippocampal structure, at least some of which may be explained by variation in hormone levels. The thesis of The Mating Mind by Geoffrey Miller considerably increased interest in using sexual selection to explain variation in brain size. From female mate choice, male–male competition, sperm competition, mating strategy, to parental care, there are some data that appear to support selection acting on one species rather than the other in sexually a selected manner but I conclude that the data are not generally supportive of the Sexual Brain Hypothesis.

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