👤 Shelby Cree

Short sleep duration, low physical activity (PA), and sedentary behavior (SB) are associated with negative health outcomes and highly prevalent in adolescents. This study examined changes in the amount and timing of PA and SB following a 1-week sleep extension manipulation in adolescents. Forty-three habitually short-sleeping (≤7 h/night on school days), habitually inactive (<3 hours of regular physical activity per week), and healthy-weight adolescents (16.0 ± 1.24 years, 69.8% female; 86% White) completed a randomized crossover procedure during the school year. Participants slept for 1 week on their typical school schedule (Typical Sleep, TS), and 1 week during which time in bed was extended by ≥1 hour each school night (Sleep Extension, EXT). Home-monitoring of sleep with wrist-worn actigraphy and activity with thigh-worn accelerometer was completed during both conditions. Relationships between sleep, SB, PA, and experimental manipulation were assessed with linear mixed models. SB and light PA (LPA) across the 24 days decreased significantly during EXT compared to TS by 72 minutes and 13.2 minutes, respectively (95% CI: -102, -42, p < .001; 95% CI: -26.4, 0.00, p = .048). SB decreased predominantly between the hours of 18:00-00:00 (-39 minute 95% CI: -54.6, -24, p < .001). There was no significant change in moderate-to-vigorous PA (MVPA) between conditions (p > .05). Increased sleep duration replaced time spent in SB primarily in the evening hours. While LPA decreased primarily in the morning hours, the amount of change was small and likely not clinically significant. Sleep extension did not impact MVPA. Show less

The glucagon-like peptide-1 receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide receptor (GIPR) are important incretin receptors that are therapeutic targets for the treatment of type 2 diabetes and obesity. This study extensively characterised the metabolic phenotype of mice with global deletion of either the GLP-1R or GIPR side by side under identical conditions. Age-matched male wild-type (WT) C57Bl6NTac, GLP-1RKO or GIPRKO mice were placed on a high-fat or chow diet for 12 weeks, and a range of in vivo (weight gain, food intake, glucose tolerance, insulin tolerance, and whole-body energy metabolism) and ex vivo (white adipocyte lipolysis, brown adipose tissue and liver mitochondrial function, adipocyte and islet size, and hepatic steatosis) parameters were measured. While both WT and GLP-1RKO mice gained weight similarly on a HFD, obese high-fat-fed GLP-1RKO mice had altered glucose and insulin tolerance, and exhibited hepatic steatosis, highlighting the physiological importance of the GLP-1R in the regulation of blood glucose and lipid homoeostasis. In contrast, GIPRKO mice were partially resistant to diet-induced obesity compared to the WT mice, which was associated with a small reduction in food intake and intact epididymal and subcutaneous white adipocyte β-adrenoceptor-mediated lipolysis. Similarly, WT mice treated with a GIPR antagonist prevented weight gain due to a reduction in food intake on a HFD. These findings provide further support that the GLP-1R is important for normal glycaemic control, whereas the GIPR may play a role in the regulation of body weight. Show less

Polycystic ovary syndrome (PCOS) is associated with increased cardiometabolic risk in young women of reproductive age. There are limited studies on atherogenic dyslipidemia, inclusive of triglycerides (TG), Apolipoprotein (apo) B-lipoproteins and remnant-cholesterol (C), atherosclerotic cardiovascular disease (ACVD), cardiac function and remodeling in young women with and without PCOS. The aim of this pilot study was to investigate the relationship of atherogenic dyslipidemia and other cardiometabolic risk factors with ACVD, cardiac function-remodeling in high-risk young overweight-obese PCOS women compared to non-PCOS and healthy-weight controls. Women with and without PCOS (non-PCOS control) aged 18 - 45 years who were overweight and obese (>25kg/m PCOS (n=48) and non-PCOS control overweight-obese age-BMI matched groups (n=19) were shown to have significantly higher fasting and non-fasting lipids including TG, remnant-C, total ApoB and ApoB48, compared to healthy-weight non-PCOS controls (n=10). PCOS and non-PCOS control overweight-obese groups had significantly higher SBP, DBP, cIMT and evidence of cardiac dysfunction and remodeling, with reduced Mitral E/A ratio, intraventricular (IV) relaxation time and increased Left ventricle (LV) end diastolic and systolic diameter, LV posterior wall thickness and IV septal thickness, compared to healthy-weight non-PCOS controls. Individuals with PCOS had significantly higher fasting plasma TG and remnant-C compared to the non-PCOS overweight-obese control group. The PCOS group tended to have 25% higher carotid plaque height, although this was not significant, compared to the non-PCOS overweight-obese control group. DBP, HOMA-IR and ApoB predicted 40% of the variability in cIMT and ApoB was shown to predict 14% of the variability in carotid plaque height, independent of age and BMI. A 1mg/ml increase in ApoB was associated with a 0.041mm increase in cIMT and a 0.75mm increase in carotid plaque height in all young women. Our pilot results supports the potential of apoB-dyslipidemia, cIMT, carotid plaque height and left ventricular diastolic dysfunction and remodeling to be used in screening for CVD risk in high-risk populations such as overweight-obese women with and without PCOS. ApoB may be useful to predict atherosclerotic vascular burden and progression of cIMT and carotid plaque, and could be used to develop a female specific algorithm for ACVD risk in high-risk young women with and without PCOS. Show less