Impact of lifelong exercise training on endothelial ischemia-reperfusion and ischemic preconditioning in humans.

Reperfusion is essential for ischemic tissue survival, but causes additional damage to the endothelium (i.e. ischemia-reperfusion [IR] injury). Ischemic preconditioning (IPC) refers to short repetitive episodes of ischemia that can protect against IR. However, IPC efficacy attenuates with older age. Whether physical inactivity contributes to the attenuated efficacy of IPC to protect against IR injury in older humans is unclear. We tested the hypotheses that lifelong exercise training relates to 1) attenuated endothelial IR and 2) maintained IPC efficacy that protects veteran athletes against endothelial IR. In 18 sedentary male individuals (SED, 20 years, 63±7 years) and 20 veteran male athletes (ATH, >5 exercise hours/week for >20 years, 63±6 years), we measured brachial artery endothelial function with flow-mediated dilation (FMD) before and after IR. We induced IR by 20-minutes of ischemia followed by 20-minutes of reperfusion. Randomized over 2 days, participants underwent either 35-minute rest or IPC (3 cycles of 5-minutes cuff inflation to 220 mmHg with 5-minutes of rest) before IR. In SED, FMD decreased after IR (median [interquartile range]): (3.0% [2.0-4.7] to 2.1% [1.5-3.9], P=0.046) and IPC did not prevent this decline (4.1% [2.6-5.2] to 2.8% [2.2-3.6],P=0.012). In ATH, FMD was preserved after IR (3.0% [1.7-5.4] to 3.0% [1.9-4.1], P=0.82) and when IPC preceded IR (3.2% [1.9-4.2] to 2.8% [1.4-4.6],P=0.18). These findings indicate that lifelong exercise training is associated with increased tolerance against endothelial IR. These protective, preconditioning effects of lifelong exercise against endothelial ischemia-reperfusion may contribute to the cardio-protective effects of exercise training

Interaction between left ventricular twist mechanics and arterial haemodynamics during localised, non-metabolic hyperaemia with and without blood flow restriction

NEW FINDINGS: What is the central question of this study? Left ventricular (LV) twist is reduced when afterload is increased, but the meaning of this specific heart muscle response and its impact on cardiac output are not well understood. What is the main finding and its importance? This study shows that LV twist responds even when arterial haemodynamics are altered only locally, and without apparent change in metabolic (i.e. heat-induced) demand. The concurrent decline in cardiac output and LV twist during partial arterial occlusion despite the increased peripheral demand caused by heat stress suggests that LV twist may be involved in the protective sensing of heart muscle stress that can override the provision of the required cardiac output. Whether left ventricular (LV) twist and untwisting rate (LV twist mechanics) respond to localised, peripheral, non-metabolic changes in arterial haemodynamics within an individual's normal afterload range is presently unknown. Furthermore, previous studies indicate that LV twist mechanics may override the provision of cardiac output, but this hypothesis has not been examined purposefully. Therefore, we acutely altered local peripheral arterial haemodynamics in 11 healthy humans (women/men n = 3/8; age 26 ± 5 years) by bilateral arm heating (BAH). Ultrasonography was used to examine arterial haemodynamics, LV twist mechanics and the twist-to-shortening ratio (TSR). To determine the arterial function-dependent contribution of LV twist mechanics to cardiac output, partial blood flow restriction to the arms was applied during BAH (BAHBFR ). Bilateral arm heating increased arm skin temperatures [change (Δ) +6.4 ± 0.9°C, P 0.05), concomitant to increases in brachial artery blood flow (Δ 212 ± 77 ml, P 0.05). Subsequently, BAHBFR reduced all parameters to preheating levels, except for TSR and heart rate, which remained at BAH levels. In conclusion, LV twist mechanics responded to local peripheral arterial haemodynamics within the normal afterload range, in part independent of TSR and heart rate. The findings suggest that LV twist mechanics may be more closely associated with intrinsic sensing of excessive pressure stress rather than being associated with the delivery of adequate cardiac output

Qualitative observation instrument to measure the quality of parent-child interactions in young children with type 1 diabetes mellitus

Background In young children with type 1 diabetes mellitus (T1DM), parents have complete responsibility for the diabetes-management. In toddlers and (pre)schoolers, the tasks needed to achieve optimal blood glucose control may interfere with normal developmental processes and could negatively affect the quality of parent–child interaction. Several observational instruments are available to measure the quality of the parent–child interaction. However, no observational instrument for diabetes-specific situations is available. Therefore, the aim of the present study was to develop a qualitative observation instrument, to be able to assess parent–child interaction during diabetes-specific situations. Methods First, in a pilot study (n = 15), the observation instrument was developed in four steps: (a) defining relevant diabetes-specific situations; (b) videotaping these situations; (c) describing all behaviors in a qualitative observation instrument; (d) evaluating usability and reliability. Next, we examined preliminary validity (total n = 77) by testing hypotheses about correlations between the observation instrument for diabetes-specific situations, a generic observation instrument and a behavioral questionnaire. Results The observation instrument to assess parent–child interaction during diabetes-specific situations, which consists of ten domains: “emotional involvement”, “limit setting”, “respect for autonomy”, “quality of instruction”, “negative behavior”, “avoidance”, “cooperative behavior”, “child’s response to injection”, “emphasis on diabetes”, and “mealtime structure”, was developed for use during a mealtime situation (including glucose monitoring and insulin administration). Conclusions The present study showed encouraging indications for the usability and inter-rater reliability (weighted kappa was 0.73) of the qualitative observation instrument. Furthermore, promising indications for the preliminary validity of the observation instrument for diabetes-specific situations were found (r ranged between |.24| and |.45| for significant correlations and between |.10| and |.23| for non-significant trends). This observation instrument could be used in future research to (a) test whether parent–child interactions are associated with outcomes (like HbA1c levels and psychosocial functioning), and (b) evaluate interventions, aimed at optimizing the quality of parent–child interactions in families with a young child with T1DM. Keywords: Type 1 diabetes mellitus, Parent–child interaction, Behavior, Children, Parents, Mealtime, Rating scal