Paracrine signalling by pancreatic δ cells determines the glycaemic set point in mice.

While pancreatic ß and α cells are considered the main drivers of blood glucose homeostasis through insulin and glucagon secretion, the contribution of δ cells and somatostatin (SST) secretion to glucose homeostasis remains unresolved. Here we provide a quantitative assessment of the physiological contribution of δ cells to the glycaemic set point in mice. Employing three orthogonal mouse models to remove SST signalling within the pancreas or transplanted islets, we demonstrate that ablating δ cells or SST leads to a sustained decrease in the glycaemic set point. This reduction coincides with a decreased glucose threshold for insulin response from ß cells, leading to increased insulin secretion to the same glucose challenge. Our data demonstrate that ß cells are sufficient to maintain stable glycaemia and reveal that the physiological role of δ cells is to provide tonic feedback inhibition that reduces the ß cell glucose threshold and consequently lowers the glycaemic set point in vivo.

Obesity and hyperinsulinemia drive adipocytes to activate a cell cycle program and senesce.

Obesity is considered an important factor for many chronic diseases, including diabetes, cardiovascular disease and cancer. The expansion of adipose tissue in obesity is due to an increase in both adipocyte progenitor differentiation and mature adipocyte cell size. Adipocytes, however, are thought to be unable to divide or enter the cell cycle. We demonstrate that mature human adipocytes unexpectedly display a gene and protein signature indicative of an active cell cycle program. Adipocyte cell cycle progression associates with obesity and hyperinsulinemia, with a concomitant increase in cell size, nuclear size and nuclear DNA content. Chronic hyperinsulinemia in vitro or in humans, however, is associated with subsequent cell cycle exit, leading to a premature senescent transcriptomic and secretory profile in adipocytes. Premature senescence is rapidly becoming recognized as an important mediator of stress-induced tissue dysfunction. By demonstrating that adipocytes can activate a cell cycle program, we define a mechanism whereby mature human adipocytes senesce. We further show that by targeting the adipocyte cell cycle program using metformin, it is possible to influence adipocyte senescence and obesity-associated adipose tissue inflammation.

Role of parents in fatigue of children with a chronic disease: a cross-sectional study.

Objective: As parents majorly impact their child's well-being, and as fatigue is a highly prevalent threat to the well-being of children with a chronic disease, we aimed to explore the association between parental factors and fatigue in children with a chronic disease. Design: Cross-sectional study. Setting: Two Dutch children's hospitals. Population: Children 2-18 years of age with either an autoimmune disease, cystic fibrosis or post-cancer treatment, and one of their parents. Main outcome measures: Paediatric fatigue was measured using the PedsQL Multidimensional Fatigue Scale. Parental factors included parental pain, fatigue and physical symptoms, parental distress, catastrophising thoughts about their child's pain and family empowerment. Multiple linear regressions were used to study associations with paediatric fatigue. A multivariable regression model was used to assess the effect of the different parental factors on paediatric fatigue. All analyses were adjusted for the age and sex of the child. Results: 204 families participated (mean age 11.0±4.3 and 43.5±6.3 years for children and parents, respectively; 69% participation rate). More parental pain, fatigue and physical symptoms, and more parental distress and pain catastrophising were associated with more paediatric fatigue. More parental empowerment was associated with less paediatric fatigue on both subscales. In the multivariable model, only paediatric age remained significantly associated with fatigue. In a separate multivariable model for children 8-18 years old, more parental distress (ß=-1.9, 95% CI -3.7 to -0.1) was also significantly associated with more paediatric fatigue. Conclusions: In a population of children with a chronic disease, parental factors, both physical and psychosocial, were associated with paediatric fatigue. Our study provides evidence that more family empowerment is associated with less paediatric fatigue. This exploratory study adds to our knowledge of associated factors with fatigue in paediatric chronic disease, providing starting points for targeted interventions.

Diagnostic accuracy of audio-based seizure detection in patients with severe epilepsy and an intellectual disability.

UNLABELLED: We evaluated the performance of audio-based detection of major seizures (tonic-clonic and long generalized tonic) in adult patients with intellectual disability living in an institute for residential care. METHODS: First, we checked in a random sample (n=17, 102 major seizures) how many patients have recognizable sounds during these seizures. In the second part of this trial, we followed 10 patients (who had major seizures with recognizable sounds) during four weeks with an acoustic monitoring system developed by CLB ('CLB-monitor') and video camera. In week 1, we adapted the sound detection threshold until, per night, a maximum of 20 sounds was found. During weeks 2-4, we selected the epilepsy-related sounds and performed independent video verification and labeling ('snoring', 'laryngeal contraction') of the seizures. The video images were also fully screened for false negatives. In the third part, algorithms in the CLB-monitor detected one specific sound (sleep-related snoring) to illustrate the value of automatic sound recognition. RESULTS: Part 1: recognizable sounds (louder than whispering) occurred in 23 (51%) of the 45 major seizures, 20 seizures (45%) were below this threshold, and 2 (4%) were without any sound. Part 2: in the follow-up group (n=10, 112 major seizures; mean: 11.2, range: 1-30), we found a mean sensitivity of 0.81 (range: 0.33-1.00) and a mean positive predictive value of 0.40 (range: 0.06-1.00). All false positive alarms (mean value: 1.29 per night) were due to minor seizures. We missed 4 seizures (3%) because of lack of sound and 10 (9%) because of sounds below the system threshold. Part 3: the machine-learning algorithms in the CLB-monitor resulted in an overall accuracy for 'snoring' of 98.3%. CONCLUSIONS: Audio detection of major seizures is possible in half of the patients. Lower sound detection thresholds may increase the proportion of suitable candidates. Human selection of seizure-related sounds has a high sensitivity and moderate positive predictive value because of minor seizures which do not need intervention. Algorithms in the CLB-monitor detect seizure-related sounds and may be used alone or in multimodal systems.

Integrated analysis of cardiac tissue structure and function for improved identification of reversible myocardial dysfunction.

BACKGROUND: Myocardial deformation imaging and contrast-enhanced cardiac magnetic resonance imaging (ceMRI) have been used to define myocardial viability in ischemic left ventricular dysfunction. This study evaluated the incremental predictive value of an integrated analysis of function and tissue structure for functional improvement after revascularization therapy. METHODS: In 59 patients with ischemic left ventricular dysfunction, myocardial viability was defined by pixel-tracking-derived myocardial deformation imaging and ceMRI to predict recovery of function at 9+/-2 months follow-up after revascularization. For each left ventricular segment in a 16-segment model, peak systolic radial strain was determined from parasternal two-dimensional echocardiographic views using an automatic frame-by-frame tracking system of natural acoustic echocardiographic markers, and extent of hyperenhancement using ceMRI. Five categories were generated for each parameter, allowing subsequent combination. The predictive power for segmental improvement in function was determined for each of the modalities as well as the combination of both. RESULTS: From 512 dysfunctional segments at baseline, 251 segments (49%) demonstrated functional recovery. The accuracy to predict functional recovery was area under curve (AUC)=0.846 for peak systolic radial strain and AUC=0.834 for extent of hyperenhancement. A combination of both parameters improved the predictive accuracy compared with hyperenhancement alone, AUC=0.861, P value of less than 0.001. In sequential Cox models, the predictive power for segmental functional recovery of extent of hyperenhancement alone (chi model 171.0, P<0.001), or peak systolic radial strain alone (chi model 205.9, P<0.001), was strengthened by a combination of both parameters (chi model 248.5, P<0.001). The advantage of image integration was particularly strong in those segments with intermediate degree of late enhancement (DeltaAUC=0.065, P<0.001). CONCLUSION: Integration of advanced information on myocardial function using deformation imaging and findings on myocardial tissue structure increases the accuracy to identify reversible myocardial dysfunction.