Linguistic laws in biology.

Linguistic laws, the common statistical patterns of human language, have been investigated by quantitative linguists for nearly a century. Recently, biologists from a range of disciplines have started to explore the prevalence of these laws beyond language, finding patterns consistent with linguistic laws across multiple levels of biological organisation, from molecular (genomes, genes, and proteins) to organismal (animal behaviour) to ecological (populations and ecosystems). We propose a new conceptual framework for the study of linguistic laws in biology, comprising and integrating distinct levels of analysis, from description to prediction to theory building. Adopting this framework will provide critical new insights into the fundamental rules of organisation underpinning natural systems, unifying linguistic laws and core theory in biology.

Effects of Exercise Rehabilitation on Physical Function in Adults With Hematological Cancer Receiving Active Treatment: A Systematic Review and Meta-Analysis.

OBJECTIVE: Evaluate the efficacy of exercise rehabilitation at improving physical function during active treatment for adults diagnosed with a hematological malignancy. DATA SOURCE: Systematic review with a multilevel meta-analysis of randomized trails was conducted. Four electronic databases, MEDLINE (EBSCOhost), CINAHL, Scopus, and CENTRAL, were searched using key words and medical subject headings. Articles were screened and assessed against the predetermined eligibility criteria. Data extracted were appraised using the Cochrane risk of bias tool for randomized trials and the GRADE guidelines. A meta-analysis examined four key clinical objectives. CONCLUSION: Twelve studies representing a total of 812 participants were included. Analysis of 36 dependent effect sizes from nine studies revealed structured and prescribed exercise interventions improved physical function (SMD = 0.39; 95% CI 0.21-0.57) compared to usual care or an active control. Exercise interventions with a multimodal design consisting of both aerobic and resistance exercise had a statistically significant effect on physical function (P < .001). Exercise intensity also had a statistically significant effect on physical function when prescribed at a moderate (P = .003) and vigorous (P < .001) intensity during active treatment in patients with leukemia or lymphoma. IMPLICATIONS FOR NURSING PRACTICE: This review suggests individuals diagnosed with leukemia or lymphoma can optimize physical function during and immediately post-treatment by attending exercise rehabilitation 3-5 times per weeks performing moderate-vigorous aerobic and resistance exercise. While further research is needed to identify optimal prescription guidelines throughout the treatment continuum, this review underscores the importance for hematology nurses to support patient referrals to exercise oncology professionals to gain positive improvements in physical function.

Training and Competition Loads in Women's Rugby Sevens Athletes: Are There Implications for Cardiovascular Health?

National- and international-level rugby sevens athletes are exposed to high training and competition loads over the course of a competitive season. Research on load monitoring and body-system responses is widespread; however, the primary focus has been on optimizing performance rather than investigating or improving cardiovascular health. There is a degree of cardiovascular remodeling, as well as local and systemic inflammation, in response to excessive exercise. These responses are moderated by many factors including previous exercise exposure, current exercise intensity and duration, age, race, and gender, as well as sport-specific physiology. For these reasons, high-performing female rugby sevens athletes may have a unique cardiovascular risk profile different from males and other rugby codes. This review aimed to characterize the training and competition loads, as well as the anthropometric and physiological profiles, of female rugby sevens athletes; discuss the potential impacts these may have on the cardiovascular system; and provide recommendations on future research regarding the relationship between rugby sevens training and competition loads and cardiovascular health. Movement demands, competition formatting, and training routines could all contribute to adverse cardiovascular adaptations. Anthropometric data and physiological characteristics may also increase the risk of cardiovascular disease. Future research needs to adopt measures of cardiovascular health to obtain a greater understanding of cardiovascular profiles and risk factors in female rugby sevens athletes.

Physical Activity Levels in People with Cancer Undergoing Chemotherapy: A Systematic Review.

OBJECTIVES: Physical activity (PA) has been shown to improve chemotherapy side effects, survival rates and treatment adherence in people with cancer. This review aimed to identify whether people undergoing chemotherapy in different exercise interventions meet PA guidelines during chemotherapy. DATA SOURCES: Databases searched were CINAHL complete, PubMed, Cochrane Library, EMBASE, AMED, Joanna Briggs Institute, OVID MEDLINE, and Google Scholar. Eligibility and risk-of-bias were reviewed by two authors. PROSPERO registration: CRD42018093839. CONCLUSION: Thirty-three studies were eligible (14 randomized controlled trials, six pre-post, and 13 cross-sectional studies), which included 2,722 people with cancer undergoing chemotherapy. Studies (n = 11/13) found PA interventions successfully increased or maintained PA participation levels, whereas PA declined without intervention. This review has identified that due to limited evidence it is not possible to determine the most appropriate intervention to improve PA for people undergoing chemotherapy. Despite the well-documented benefits of PA, most people undergoing chemotherapy do not achieve the PA guidelines. Clinicians should be aware that during treatment, participants may not meet PA guidelines even if they participate in an intervention. However, interventions may prevent PA levels from declining. Further research is required to determine the most effective approaches to increase PA levels while undergoing chemotherapy. IMPLICATIONS FOR NURSING PRACTICE: Nurses are well placed to have conversations with patients undergoing chemotherapy regarding PA levels. PA should be considered as part of a treatment regimen. Tailored advice must be provided aiming to improve health outcomes. Referral to an exercise professional is best practice to improve the uptake of PA.

Testing the validation and reliability of the Caregiver-Patient Activation Measure (CG-PAM).

Objective: The objective of this study was to test the reliability and validity of the Caregiver-Patient Activation Measure (CG-PAM). Methods: Based on the psychometric testing of the original Patient Activation Measure (PAM), three assessments of reliability and validity were completed on the CG-PAM. Test-retest reliability was assessed across two weeks (n = 23). Criterion validity was assessed by interviewing participants from the test-retest cohort (n = 10), with transcripts assessed by subject matter experts (n = 3) to classify activation levels of the interviewee. Construct validity was assessed through a survey (n = 179) consisting of demographic questions, the CG-PAM and concepts hypothesised to be related to caregiver activation. Results: There was strong test-retest reliability (r = 0.893), but poor criterion validity. Assessment o;f construct validity demonstrated significant relationships found between caregiver activation and weekly hours of care provided (p < 0.001), relationship satisfaction (p < 0.001), and dyad typology (p < 0.001), but not with perceived levels of stress or social support. Conclusion: The CG-PAM was found to have strong reliability, but there were inconsistent results across the validation tests conducted. Innovation: Future research must consider the dynamic nature of caring and the importance of the relationship between the caregiver/recipient when defining activation levels within the CG-PAM.

Linguistic laws in biology.

Linguistic laws, the common statistical patterns of human language, have been investigated by quantitative linguists for nearly a century. Recently, biologists from a range of disciplines have started to explore the prevalence of these laws beyond language, finding patterns consistent with linguistic laws across multiple levels of biological organisation, from molecular (genomes, genes, and proteins) to organismal (animal behaviour) to ecological (populations and ecosystems). We propose a new conceptual framework for the study of linguistic laws in biology, comprising and integrating distinct levels of analysis, from description to prediction to theory building. Adopting this framework will provide critical new insights into the fundamental rules of organisation underpinning natural systems, unifying linguistic laws and core theory in biology.

Dominance style is a key predictor of vocal use and evolution across nonhuman primates.

Animal communication has long been thought to be subject to pressures and constraints associated with social relationships. However, our understanding of how the nature and quality of social relationships relates to the use and evolution of communication is limited by a lack of directly comparable methods across multiple levels of analysis. Here, we analysed observational data from 111 wild groups belonging to 26 non-human primate species, to test how vocal communication relates to dominance style (the strictness with which a dominance hierarchy is enforced, ranging from 'despotic' to 'tolerant'). At the individual-level, we found that dominant individuals who were more tolerant vocalized at a higher rate than their despotic counterparts. This indicates that tolerance within a relationship may place pressure on the dominant partner to communicate more during social interactions. At the species-level, however, despotic species exhibited a larger repertoire of hierarchy-related vocalizations than their tolerant counterparts. Findings suggest primate signals are used and evolve in tandem with the nature of interactions that characterize individuals' social relationships.

Heart rate variability improves in 3-5-year-old children following a 6-month physical activity-based intervention: the Active Early Learning (AEL) cluster randomised controlled trial.

Heart rate variability (HRV) measurement provides non-invasive assessment of autonomic stability and cardiometabolic disease risk. Insufficient physical activity in early childhood may contribute to negative cardiometabolic health. The Active Early Learning (AEL) study was a 6-month randomised controlled trial investigating the effects of a physical activity-based program incorporating movement within the daily curriculum of preschool children. The current study assessed the effects of the AEL intervention on HRV as a measure of cardiac vagal control. Children aged between 3-5 years and enrolled in a preschool with an attendance of ≥15 children were eligible. Physical activity was recorded using an Actigraph wGT3x accelerometer worn at the waist of participants over 3 consecutive days. A Polar H10 chest strap measured HRV with the HF-band and RMSSD representing cardiac vagal control. After 6 months of the AEL trial, linear mixed model analyses revealed a significant intervention effect for increased HF (p = 0.044). The control group did not demonstrate changes in cardiac vagal control after the intervention ceased. Independent of age, sex, physical activity and BMI, the AEL study elicited significant improvements in the cardiac vagal control of participants who received the intervention. Findings highlight the importance of investigating HRV for assessing the cardiometabolic health in young children. ANZCTR trial registration number: ACTRN12619000638134. Novelty: The AEL curriculum improved child HRV independent of age, sex, physical activity and BMI. Heart rate and RR intervals did not demonstrate changes for the intervention and control groups. Multivariate programs for developing physical competence, confidence, knowledge and motivation may improve child health.

Relationship between heart rate variability and body mass index: A cross-sectional study of preschool children.

Reduced heart rate variability (HRV) is associated with overweight and obesity in adults. However, little is known about this relationship in early childhood. We investigated the relationship between resting vagally-mediated HRV and body mass index (BMI) in Australian preschool children. Children were recruited from 13 non-government early learning centres located in Queensland and New South Wales, Australia. From this population-based sample, data from 146 healthy children (58 females) between 3 and 5 years of age (mean age 4.35 ± 0.44 years) were analysed. BMI was calculated from child body weight and height. Physical activity was recorded using an Actigraph wGT3x accelerometer worn at the waist of participants over 3 consecutive days. A Polar H10 chest strap measured seated, resting RR intervals for the calculation of HRV with the root mean square of successive differences (RMSSD) reflecting vagally-mediated activity. The relationship between HRV and BMI was analysed using a linear mixed model adjusted for age, sex and physical activity. Analysis revealed that RMSSD (ln) demonstrated a significant inverse relationship with BMI (ß = -0.06; 95% CI = -0.12 - -0.01; p = 0.032), and the model accounted for 23% of the variance in RMSSD (ln). Notably, a one unit increase in BMI resulted in a reduction in RMSDD (ln) of 0.06. This investigation demonstrated evidence for a significant inverse linear relationship between vagally-mediated HRV and BMI in 3 - 5-year-old Australian children, similar to that of adults. Furthermore, this relationship was independent of age, sex and physical activity levels. Results may indicate that the cardiometabolic health of preschool children is, in part, influenced by the relationship between vagally-mediated HRV and weight status.

Physical activity for people living with cancer: Knowledge, attitudes, and practices of general practitioners in Australia.

BACKGROUND: Healthcare professionals' (Oncologists, doctors, and nurses) physical activity (PA) recommendations impact patients living with cancer PA levels. General practitioners (GPs) monitor the overall health of patients living with cancer throughout their treatment journey. This is the first study to explore GP's knowledge, attitudes and practices of PA for patients living with cancer. METHODS: GPs who see patients living with cancer regularly (n = 111) completed a survey based on The Theory of Planned Behaviour (TPB). Participants (GP's) reported knowledge, attitudes, perceived behaviour control and subjective norms of PA within the cancer population. GP recommendation and referral rates of PA were reported. Principal component analysis was conducted to establish a set of survey items aligned to TPB constructs (attitude, subjective norms, perceived control), and multiple regression analyses characterised associations between these predictor variables and (a) recommendation; and (b) referral-of PA to cancer patients. RESULTS: GPs (n = 111) recommended PA to 41-60% of their patients and referred 1-20% to PA programs. Multiple regression models significantly predicted the percent of patients recommended PA, p < .0005 adj. R2 = 0.40 and referred PA, p < .0005, adj. R2 = 0.21. GP attitudes and perceived behavioural control and GP's own activity levels were significant predictors of whether patients were recommended and referred for PA, p<0.05. CONCLUSION: GPs reported positive attitudes and perceptions towards promoting PA for their patients living with cancer. Despite having a positive correlation between PA recommendations and referral rates, a gap was evident between GP's PA beliefs and their individual referral practices. More GP's willing to promote and refer their patients for PA, would improve the physical and mental health outcomes of the cancer population.

Health Care Professionals' Knowledge and Attitudes Toward Physical Activity in Cancer Patients: A Systematic Review.

OBJECTIVES: The purpose of this study was to, combine current available literature across health professionals to determine commonalities and differences between knowledge and attitudes of physical activity (PA) and its importance within the cancer population. It aimed to identify any gaps in the literature to inform future study directions to enhance PA participation and improve health outcomes and quality of life. DATA SOURCES: Design: systematic review. DATA SOURCES: Google Scholar, EBSCO, PubMed, Scopus, Web of Science. INCLUSION CRITERIA: survey-based studies specifically reporting PA levels for both cancer patients and survivors from the perspective of oncology health care professionals. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) was used to guide this review. The initial search highlighted 15,342 articles and returned 190 articles with relevant titles, of which 20 met the eligibility criteria; 15.8% of cancer patients reported to meeting PA guidelines during treatment and 36.5% after treatment. On average 58.1% of health care professionals self-reported discussing PA with their cancer patients, with the average referral rate to an exercise specialist or rehabilitation program being 18.3%. CONCLUSION: Only a limited number of health care professionals are initiating a discussion about PA with their cancer patients. Some health care professionals reported limited knowledge of PA guidelines for cancer patients. Their own personal PA levels do not seem to be associated with whether they discuss PA with their patients. Common barriers to providing PA advice were experienced across all health care professions such as time, limited referral pathways, and patient interest. Future research should be carried out to substantiate these barriers and discover which strategies could be implemented to improve the levels of PA discussions and referrals within clinical practice. IMPLICATIONS FOR NURSING PRACTICE: Given the position nurses hold within the health care system, it would be beneficial to upskill and improve their understanding of PA and exercise as medicine for the cancer population. This has enormous potential that could enhance PA advice and boost referrals to exercise professionals improving the health and quality of life of the cancer population.

Improved behavioral indices of welfare in continuous compared to intermittent pair-housing in adult female rhesus macaques (Macaca mulatta).

Limiting opportunities for captive nonhuman primates (NHPs) to express species-specific social behaviors may disrupt the adaptive drive for social companionship and may lead to increases in coping behaviors and inactivity. While captive NHPs show improved welfare when moving to pair-housing from single-housing, the impact of daily separation of pair-mates, as is implemented in intermittent pair-housing, is not fully understood. We compared behavioral indices of welfare exhibited by adult female rhesus macaques (Macaca mulatta) in two conditions: (1) intermittent pair-housing, involving daily overnight separation of pair-mates, and (2) continuous pair-housing, involving little separation of pair-mates. A within-subjects study design tested two groups of females experiencing both pairing conditions in an alternate order, switching either from continuous to intermittent pair-housing, or from intermittent to continuous pair-housing. Behavioral observations, recording activity state, self-directed, abnormal, and social behaviors, were conducted at midday when all females were paired, and in the afternoon when intermittent pairs were separated. Females exhibited higher levels of inactivity and self-directed behavior when separated due to intermittent pair-housing in comparison to continuous pair-housing. In addition, intermittently paired females showed higher levels of grooming and other types of affiliation when paired, than during the same time frame when they were continuously paired. These results suggest that females in the continuous presence of a social partner experience improved levels of activity and do not need to elevate levels of behavioral coping mechanisms (e.g., self-scratching, increased affiliation) as they receive the benefits associated with social companionship consistently throughout the day. Overall, this study provides the first evidence that continuous pair-housing affords better welfare than intermittent pair-housing in adult female rhesus macaques. Pair-housing options, such as continuous pairing, that reduce reliance on behavioral coping mechanisms and promote adaptive social behavior throughout the entirety of the day should be prioritized over husbandry care scheduled for convenience.

The impact of high-intensity interval training exercise on breast cancer survivors: a pilot study to explore fitness, cardiac regulation and biomarkers of the stress systems.

BACKGROUND: Cardiovascular disease (CVD) remains the largest cause of death in breast cancer survivors. The aim of this study was to explore the impact of exercise intensity on aerobic fitness and autonomic cardiac regulation (heart rate variability (HRV)) and salivary biomarkers of the stress systems (HPA-axis, cortisol; sympathetic nervous system, α-amylase) and mucosal immunity (secretory(s)-IgA), markers of increased risk of CVD in breast cancer survivors. METHODS: Participants were randomly assigned to; 1) high intensity interval training (HIIT); 2) moderate-intensity, continuous aerobic training (CMIT); or 3) a wait-list control (CON) for a 12-week (36 session) stationary cycling intervention. Cardiorespiratory fitness (VO2peak), resting HRV and salivary biomarkers were measured at baseline 2-4 d pre-intervention and 2-4 d post the last exercise session. RESULTS: Seventeen participants were included in this study (62 ± 8 years, HIIT; n = 6, CMIT; n = 5, CON; n = 6). A significant improvement (p ≤ 0.05) was observed for VO2peak in the HIIT group; 19.3% (B = 3.98, 95%CI = [1.89; 4.02]) and a non-significant increase in the CMIT group; 5.6% (B = 1.96, 95%CI = [- 0.11; 4.03]), compared with a 2.6% (B = - 0.64, 95%CI = [- 2.10; 0.82]) decrease in the CON group. Post intervention improvements in HRV markers of vagal activity (log (ln)LF/HF, LnRMSSD) and sympathetic nervous system (α-amylase waking response) occurred for individuals exhibiting outlying (> 95% CI) levels at baseline compared to general population. CONCLUSION: High intensity interval training improved cardiovascular fitness in breast cancer survivors and improved cardiac regulation, and sympathetic nervous system (stress) responses in some individuals. High-intensity interval training was safe and effective for breast cancer survivors to participate in with promising results as a time efficient intensity to improve physical health and stress, reducing CVD risk. TRIAL REGISTRATION: This pilot study was retrospectively registered through the Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12620000684921 .

Acute Physiological Responses Following a Bout of Vigorous Exercise in Military Soldiers and First Responders with PTSD: An Exploratory Pilot Study.

Post-traumatic stress disorder (PTSD) is a prevalent and debilitating condition associated with psychological conditions and chronic diseases that may be underpinned by dysfunction in the autonomic nervous system (ANS), the hypothalamic-pituitary-adrenal (HPA) axis and chronic systemic low-grade inflammation. The objective of this pilot study was to determine psychological, ANS [heart rate variability (HRV)], HPA (salivary cortisol) and inflammatory (salivary C-Reactive Protein) responses to a bout of vigorous exercise in male first responders, military veterans and active duty personnel with (n = 4) and without (n = 4) PTSD. Participants (50.1 ± 14.8 years) performed a thirteen-minute, vigorous intensity (70%-80% of heart rate max), one-on-one boxing session with a certified coach. Physiological and psychological parameters were measured before, during, immediately after to 30 min post-exercise, and then at 24 h and 48 h post. The effect sizes demonstrated large to very large reductions in HRV that lasted up to 48 h post-exercise in the PTSD group compared with unclear effects in the trauma-exposed control (TEC) group. There were unclear effects for depression, anxiety and stress as well as salivary biomarkers for both groups at all time-points. Findings may reflect stress-induced changes to the ANS for PTSD sufferers.

Heart rate variability for determining autonomic nervous system effects of lifestyle behaviors in early life: A systematic review.

BACKGROUND: An unhealthy lifestyle negatively alters autonomic nervous system (ANS) activity as reflected by decreased heart rate variability (HRV), increasing cardiovascular disease (CVD) risk. Research investigating the effect of modifiable lifestyle factors on ANS activity in young children is limited. Early identification of these risk factors is vital to improving long-term individual and public health outcomes. A systematic review was conducted to assess the effect of maternal or child modifiable lifestyle factors on child ANS activity. METHODS: Following the 2009 PRISMA guidelines, three electronic databases were searched from February 2018 - July 2019 for articles describing human trials between 1996 - 2019. Included studies examined ANS activity of children between 28 weeks gestational age - 6 years in relation to modifiable lifestyle CVD risk factors. RESULTS: Twenty-six studies fulfilled inclusion criteria. Sixteen studies reported that modifiable lifestyle factors significantly influenced the HRV of children. Increased HRV was significantly associated with higher maternal zinc and omega-3 fatty acid intake, regular maternal aerobic exercise and a non-smoking environment. Child diet and body composition demonstrated some support for an association between these modifiable lifestyle factors and child HRV. CONCLUSION: There is cross-sectional evidence supporting an association between maternal lifestyle factors and child HRV. Evidence is less supportive of a relationship between child modifiable lifestyle factors and child HRV. Monitoring the effects of lifestyle interventions on the ANS via HRV measurements of both mother and child may identify child CVD risk.

Measuring Heart Rate Variability Using Commercially Available Devices in Healthy Children: A Validity and Reliability Study.

Heart rate variability (HRV) is an accepted method for determining autonomic nervous system activity and cardiovascular risk in various populations. This study assessed the validity and reliability of a commercially available finger photoplethysmography (PPG) system for measuring pediatric HRV in a real-world setting. Sixteen healthy children (4.06 ± 0.58 years) were recruited. The PPG system was compared to the Polar H10 heart rate (HR) sensor validated against ECG (gold standard) for HRV measurement. Seated short-term resting R-R intervals were recorded simultaneously using both systems. Recordings were performed on 3 days at the participants' school. Paired t-tests, effect sizes and Bland-Altman analyses determined the validity of the PPG system. The relative and absolute reliability of both systems were calculated. No HRV parameters were valid for the PPG system. Polar H10 yielded moderate (0.50-0.75) to good (0.75-0.90) relative reliability with R-R intervals and the standard deviation of instantaneous and continuous R-R variability ratio showing the best results (ICCs = 0.84). Polar H10 displayed better absolute reliability with the root mean square of successive differences, R-R intervals and HR showing the lowest values (TEM% < 12%). The use of the Polar H10 and not the PPG system is encouraged for HRV measurement of young children in an educational real-world setting.

Lifestyle Modification for Enhancing Autonomic Cardiac Regulation in Children: The Role of Exercise.

Decreased physical activity (PA) is a global concern contributing to the rise in cardiometabolic diseases. One potential mechanism linking insufficient PA and poor health is dysregulated autonomic nervous system (ANS) activity. This relationship is established in adults and PA recommendations, with specific exercise prescription guidelines, have been proposed to overcome this societal health burden. However, research on the benefits and underlying mechanisms of exercise on ANS activity in children <18 years old is limited. This review aimed to describe the optimal exercise "dose" and potential mechanisms of action that exercise may pose on enhancing child ANS activity, represented by heart rate variability (HRV). PubMed, Web of Science and Google Scholar were searched for articles examining the influence of exercise on child HRV. Various exercise duration and frequency combinations appear to improve HRV indices, primarily those representing parasympathetic influence. Furthermore, both aerobic and resistance training benefit HRV through potentially different mechanisms with intensity proposed to be important for exercise prescription. Findings indicate that exercise is a crucial lifestyle modification with protective and therapeutic effects on cardiometabolic health associated with improvements in child ANS activity. Exercise programming must consider the various components including mode, intensity and population characteristics to optimize ANS health.

HPA axis function and diurnal cortisol in post-traumatic stress disorder: A systematic review.

BACKGROUND: There is inconsistency in the literature regarding the nature of hypothalamic-pituitary-adrenal (HPA) axis functionality in post-traumatic stress disorder (PTSD). PURPOSE: The review aimed to investigate HPA axis functionality via the diurnal profile of cortisol as it relates to PTSD. METHODS: The authors conducted a systematic review of the literature from June 2017 - March 2019 in accordance with The PRISMA Statement in the following four databases: PubMed, MEDLINE, ScienceDirect and PsycINFO with Full Text. The search strategy was limited to articles in English language, published in peer-reviewed journals within the last decade and human studies. Search terms included "post-traumatic stress disorder" OR "PTSD", AND "hypothalamic pituitary adrenal axis" OR "HPA axis" AND "diurnal cortisol" OR "cortisol". PTSD sufferers of all trauma types, genders and socioeconomic statuses were included provided there was a "healthy" control group and an inclusion of reporting on inter-group measurements of diurnal cortisol profiles as a portrayal of HPA axis functionality. RESULTS: A total of 10 studies met the criteria for inclusion in this review. The association between HPA axis functionality and PTSD was evaluated by the measurement of salivary and/or plasma cortisol concentrations. Only two studies demonstrated an association between PTSD and diurnal cortisol when compared with respective control groups while three studies found no associations. The remaining five studies found partial, mostly negative associations between PTSD and diurnal cortisol. CONCLUSION: Despite some indications of an association between PTSD and dysregulated HPA axis functionality as demonstrated by diurnal cortisol output, the current review has revealed mixed findings. As such, a complete understanding of HPA axis dysregulation as it relates to PTSD remains unestablished. Given the findings, further investigation into the relationship between PTSD trauma-exposed and non-PTSD trauma-exposed individuals and diurnal cortisol is warranted.

Cardiac autonomic function and its association with cardiometabolic disease risk factors in Black South African children.

OBJECTIVE: This study evaluated the associations between cardiac autonomic nervous system (ANS) activity and cardiometabolic disease (CMD) risk factors among black South African children. DESIGN: The participants included 34 black South African children (11.85 ±â€¯0.89 y). CMD risk factors included waist circumference (WC), hip circumference (HC), body mass index z-score (BMI z-score), blood pressure (SBP, DBP), total cholesterol (TC), high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), fasting glucose (FG), fasting insulin (FINS), and vessel stiffness index (SI). Heart rate variability was used to quantify cardiac ANS activity. RESULTS: lnRMSSD, pNN50 and lnSD1 were inversely associated with FINS (r = -0.33, p = 0.05; r = -0.36, p = 0.03; r = -0.41, p = 0.01), WC (r = -0.45, p = 0.01; r = -0.39, p = 0.02; r = -0.45, p = 0.01), and HC (r = -0.41, p = 0.01; r = -0.36, p = 0.03; r = -0.43, p = 0.01). HDL was positively associated with lnRMSSD (r = 0.37; p = 0.03) and lnSD1 (r = 0.37; p = 0.03) while, LDL was negatively associated with HF (r = -0.41; p = 0.01). Regression analysis identified WC as the primary predictor for parasympathetic modulation in time domain (lnRMSSD: r2 = 0.21, p = 0.01; pNN50: r2 = 0.18, p = 0.01) and non-linear domain (lnSD1: r2 = 0.21, p = 0.01). CONCLUSION: Elevated resting parasympathetic activity in children is associated with lower CMD risk factors and an elevation in the protective HDL.