Exploring the relationship between sleep and aggression in adolescents: A cross sectional study using the UK Millennium cohort study

This study aimed to establish if a significant relationship exists between sleep and aggression in a large representative adolescent cohort and explores the impact of potential confounders. This cross-sectional secondary data analysis included 10,866 males and females aged 13-15 years, from the UK-based 2015 Millenium Cohort Study (sixth sweep). Independent variables included self-report measures of sleep duration and quality. The parent reported 'Strengths and Difficulties Questionnaire' conduct score measured aggression. Binary logistic regression examined independent associations between each sleep variable and aggression. Multiple regression models then adjusted for potential confounders: age, sex, socioeconomic status, arousal, and affect. Under 8 hours of sleep on average was significantly associated with aggression when age, sex and income were controlled (p = .008). This became insignificant following adjustment for both affect and arousal. Sleep quality remained significantly associated with aggression when all confounders were controlled: 'sleep onset latency >30 minutes' and 'wakening at least a good bit of the time' increased the odds of aggression by around 27.9% (p < .001) and 43.5% respectively (p < .001). A significant association exists between poor subjective sleep quality and heightened aggression in this cohort, when all our confounders are controlled, identifying sleep quality as a potential target in treating adolescent aggression.

Effect of yeast cell wall supplementation on intestinal integrity, digestive enzyme activity and immune traits of broilers

1. The protective layer formed by intestinal epithelial cells acts as a barrier preventing the adhesion of pathogenic bacteria, aids digestion and passage of nutrients and reduces damage caused from toxins on the gastrointestinal tract. This study was conducted to investigate the effects of a yeast cell wall-based product (YCW), on broiler intestinal integrity, digestive enzyme capacity and immune function.2. A 35-d trial involving 246, one-d-of-hatch male broiler chickens was carried out at a trial facility at Agri-Food Biosciences Institute (AFBI, Belfast, UK). Birds were randomly allocated into 6 pens at day of hatch (41 birds/pen; 123 birds/group). Pens were divided into two groups: (1) basal diet and (2) basal diet that incorporated YCW at the manufacturers' recommended inclusion levels (Alltech Inc., Lexington, Kentucky, USA).3. In this study, YCW supplementation affected broiler intestinal morphology resulting in greater crypt depth, villus height and surface area, goblet cell density and mucus layer thickness and lower muscularis mucosae thickness. The digestive enzymes, maltase, sucrase and alkaline phosphatase, were significantly higher in the YCW supplemented group compared to the control. The expression levels of pro-inflammatory cytokines, IL-1β, IL-12 and IL-18, were significantly lower as was necroptotic cell death in YCW supplemented birds.4. In conclusion, under the conditions of this study, YCW supplementation positively affected intestinal health parameters in broilers following 35-d supplementation.

Mitochondrial DNA quantification as a tool for embryo viability assessment: retrospective analysis of data from single euploid blastocyst transfers

STUDY QUESTION

Does the amount of mitochondrial DNA (mtDNA) in blastocyst biopsy specimens have the potential to serve as a biomarker of euploid embryo implantation ability, independent of morphology?

SUMMARY ANSWER

The results of this study strongly suggest that elevated mtDNA levels, above a previously defined threshold, are strongly associated with blastocyst implantation failure and represent an independent biomarker of embryo viability.

WHAT IS KNOWN ALREADY

Improved methods of embryo selection are highly desirable in order to increase the efficiency of IVF treatment. At present, even the transfer of chromosomally normal embryos of high morphological grade cannot guarantee that a pregnancy will follow. Recently, it has been proposed that the quantity of mtDNA in embryonic cells may be an indicator of developmental potential, with higher levels of mtDNA associated with reduced implantation. However, thus far reported data sets have been relatively small and in some cases have lacked appropriate validation.

STUDY DESIGN, SIZE, DURATION

This large, blinded, retrospective study involved the analysis of relative mtDNA levels in 1505 euploid blastocysts obtained from 490 couples undergoing preimplantation genetic testing for aneuploidy. Implantation outcomes were compared to mtDNA levels in order to determine the capacity of the method to predict viability and to assess the validity of previously established thresholds.

PARTICIPANTS/MATERIALS, SETTING, METHODS

DNA from blastocyst biopsy samples was amplified and then subjected to aneuploidy analysis using next generation sequencing or array comparative genomic hybridization. Only those embryos classified as chromosomally normal had their mtDNA levels assessed. This analysis was undertaken retrospectively using quantitative real-time PCR, without knowledge of the outcome of embryo transfer. Predictions of implantation failure, based upon mtDNA levels were subsequently compared to the observed clinical results. All cycles involved the transfer of a single embryo.

MAIN RESULTS AND THE ROLE OF CHANCE

Of all blastocysts analyzed, 9.2% (139/1505) contained mtDNA levels above a previously established viability threshold and were therefore predicted to have reduced chances of implantation. To the date of analysis, 282 euploid blastocysts had been transferred with an overall implantation rate of 65.6% (185/282). Of the transferred embryos, 249 contained levels of mtDNA in the normal range, 185 of which produced a pregnancy, giving an implantation rate of 74.3% for euploid embryos with 'normal' quantities of mtDNA. However, 33 of the transferred embryos were determined to have elevated mtDNA quantities. None of these led to a pregnancy. Therefore, the negative predictive value of mtDNA assessment in this cohort was 100% (33/33). The difference between the implantation rates for embryos with normal and elevated mtDNA levels was highly significant (P < 0.0001). The mtDNA thresholds, used for classification of embryos, were unaffected by female age or the clinic in which the IVF was undertaken. The probability of an embryo having elevated levels of mtDNA was not influenced by variation in embryo morphology.

LIMITATIONS, REASONS FOR CAUTION

This study provides strong evidence that mtDNA quantification can serve as a valuable tool to assist the evaluation of blastocyst viability. However, to determine the true extent of any clinical benefits, other types of investigations, such as non-selection studies and randomized controlled trials, will also be necessary.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this study suggest that mtDNA quantity can serve as an independent biomarker for the prediction of euploid blastocyst implantation potential. Prospective studies should now be undertaken to confirm these results. Additionally, investigations into the underlying biological cause(s) of elevated mtDNA levels and an enhanced understanding of how they relate to diminished implantation potential would be invaluable.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by funding provided by Reprogenetics. None of the authors have any competing interests.