Structural and functional analysis of the human Rad50 and Mre11 DNA repair complex : reaching out for flexible solutions

DNA, the genetic material, contains essential information for the proper function of cells. lt is therefore of great importance that the integrity of the genome is carefully maintained during metabolic processes. Special challenges for genome maintenance pathways are DNA ends that arise in cells due to different causes. DNA ends, in the form of telomeres, naturally occur at the termini of the linear eukaryotic chromosomes. Random DNA double-strand breaks (DSBs) can be induced by various exogenous and endogenous DNA darnaging agents. In contrast, the cell can intentionally induce sitespecific DSBs in specialized processes to create genetic diversity during immune system development and meiosis. Impraper processing of these DNA ends imposes a high risk for genetic rearrangements that can lead to cell death, cell maltunetion or carcinogenesis. Therefore, it is of great importance that the DNA ends are processed and/or repaired accurately. For this purpose several mechanisms exist that depend on specific specialized protein machineries. The DSB repair pathway used depends on the circumstances under which the break occurs. One protein complex that is involved in multiple genome maintenance pathways that deal with DNA ends consists of three proteins: Rad50, Mre11 and Nbs1. The aim of this thesis is to ga in insights in the role of this Rad50 protein complex in DNA end metabolis

Perceptions, experiences, barriers and facilitators regarding nutritional intake of patients with chronic limb threatening ischemia:a qualitative study

Objective: Patients with chronic limb threatening ischemia (CLTI) are at high risk for amputation and other cardiovascular adverse events. Nutrition-related symptoms and malnutrition are common in the CLTI population, and lead to worse clinical outcomes. Understanding of the factors influencing nutritional intake is required to determine whether optimization of nutritional intake in this population requires interventions. Therefore, this study aimed to describe perceptions and experiences on nutrition of patients with CLTI, and to identify perceived barriers and facilitators influencing their nutritional intake.Methods: In this phenomenological qualitative study, individual semi-structured, face-to-face interviews were conducted with patients with CLTI who lived independently. Interviews were transcribed verbatim, and reflexive thematic analysis was performed.Results: Twelve participants were interviewed. Five themes were generated: (1) lack of nutritional risk perception, (2) role of nutrition for health, functioning and surviving, (3) multiple factors influencing nutritional intake, (4) limited nutritional advice, and (5) no intention to change current nutritional intake.Conclusion: Patients with CLTI perceive nutritional intake as a necessity to survive and function. Patients express limited risk perception regarding adequate nutritional intake and undernutrition. Nutritional intake is mainly based on non-health related factors, as habits and taste, and multiple barriers hinder nutritional intake. Patients received no or only limited nutritional advice. Together this leads to an expressed lack of intention to change nutritional intake. Findings of this study stress the urgency for patient-centered nutritional support, to increase nutrition-related knowledge and motivation, to prevent or treat undernutrition, and may improve clinical outcomes in patients with CLTI

Expectations and Experiences of Participating in a Supervised and Home-Based Physical Exercise Intervention in Patients with Head and Neck Cancer during Chemoradiotherapy: A Qualitative Study

(1) Background: Chemoradiotherapy (CRT) for head and neck cancer (HNC) is associated with severe toxicity resulting in fatigue and weight loss, including loss of skeletal muscle mass. Exercise interventions might positively affect physical fitness and quality of life. Sufficient adherence and compliance rates are necessary for optimal effects. This study aimed to gain insight into expectations and experiences and factors influencing adherence, retention and compliance of HNC patients participating in exercise intervention during CRT. (2) Methods: Consecutive participants were invited for semi-structured interviews, conducted pre- and post-intervention. A deductive approach was used to identify themes and factors influencing adherence, retention and compliance. (3) Results: Thematic saturation was reached after interviewing 14 patients pre-intervention. Five themes were identified: planning and time management, treatment toxicity, motivation to exercise, exercise intervention and supervision by a physiotherapist. The intensity of the treatment schedule and treatment toxicity were important barriers. Facilitators mentioned were physical and emotional benefits, social support as well as the simplicity and home-based setting of the intervention. (4) Conclusions: A personalised approach, considering the individual facilitators and barriers of HNC patients, is important to increase adherence, retention and compliance to exercise intervention and to reap the optimal effects of the program

Genomic Alterations Associated with Estrogen Receptor Pathway Activity in Metastatic Breast Cancer Have a Differential Impact on Downstream ER Signaling

Mutations in the estrogen receptor gene ( ESR1), its transcriptional regulators, and the mitogen-activated protein kinase (MAPK) pathway are enriched in patients with endocrine-resistant metastatic breast cancer (MBC). Here, we integrated whole genome sequencing with RNA sequencing data from the same samples of 101 ER-positive/HER2-negative MBC patients who underwent a tumor biopsy prior to the start of a new line of treatment for MBC (CPCT-02 study, NCT01855477) to analyze the downstream effects of DNA alterations previously linked to endocrine resistance, thereby gaining a better understanding of the associated mechanisms. Hierarchical clustering was performed using expression of ESR1 target genes. Genomic alterations at the DNA level, gene expression levels, and last administered therapy were compared between the identified clusters. Hierarchical clustering revealed two distinct clusters, one of which was characterized by increased expression of ESR1 and its target genes. Samples in this cluster were significantly enriched for mutations in ESR1 and amplifications in FGFR1 and TSPYL. Patients in the other cluster showed relatively lower expression levels of ESR1 and its target genes, comparable to ER-negative samples, and more often received endocrine therapy as their last treatment before biopsy. Genes in the MAPK-pathway, including NF1, and ESR1 transcriptional regulators were evenly distributed. In conclusion, RNA sequencing identified a subgroup of patients with clear expression of ESR1 and its downstream targets, probably still benefiting from ER-targeting agents. The lower ER expression in the other subgroup might be partially explained by ER activity still being blocked by recently administered endocrine treatment, indicating that biopsy timing relative to endocrine treatment needs to be considered when interpreting transcriptomic data

Neutral Effects of Combined Treatment With GLP-1R Agonist Exenatide and MR Antagonist Potassium Canrenoate on Cardiac Function in Porcine and Murine Chronic Heart Failure Models

Background: Ischemia-reperfusion and cardiac remodeling is associated with cardiomyocyte death, excessive fibrosis formation, and functional decline, eventually resulting in heart failure (HF). Glucagon-like peptide (GLP)-1 agonists are reported to reduce apoptosis and myocardial infarct size after ischemia-reperfusion. Moreover, mineralocorticoid receptor antagonists (MRAs) have been described to reduce reactive fibrosis and improve cardiac function. Here, we investigated whether combined treatment with GLP-1R agonist exenatide and MRA potassium canrenoate could minimize cardiac injury and limit HF progression in animal models of chronic HF. Methods and Results: Forty female Topigs Norsvin pigs were subjected to 150 min balloon occlusion of the left anterior descending artery (LAD). Prior to reperfusion, pigs were randomly assigned to placebo or combination therapy (either low dose or high dose). Treatment was applied for two consecutive days or for 8 weeks with a continued high dose via a tunneled intravenous catheter. Using 2,3,5-Triphenyltetrazolium chloride (TTC) staining we observed that combination therapy did not affect the scar size after 8 weeks. In line, left ventricular volume and function assessed by three-dimensional (3D) echocardiography (baseline, 7 days and 8 weeks), and cardiac magnetic resonance imaging (CMR, 8 weeks) did not differ between experimental groups. In addition, 36 C57Bl/6JRj mice underwent permanent LAD-occlusion and were treated with either placebo or combination therapy prior to reperfusion, for two consecutive days via intravenous injection, followed by continued treatment via placement of osmotic mini-pumps for 28 days. Global cardiac function, assessed by 3D echocardiography performed at baseline, 7, 14, and 28 days, did not differ between treatment groups. Also, no differences were observed in cardiac hypertrophy, assessed by heart weight/bodyweight and heart weight/tibia length ratio. Conclusion: In the current study, combined treatment with GLP-1R agonist exenatide and MR antagonist potassium canrenoate did not show beneficial effects on cardiac remodeling nor resulted in functional improvement in a small and large animal chronic HF model

Involvement of the endocannabinoid system in reward processing in the human brain

Rationale Disturbed reward processing in humans has been associated with a number of disorders, such as depression, addiction, and attention-deficit hyperactivity disorder. The endocannabinoid (eCB) system has been implicated in reward processing in animals, but in humans, the relation between eCB functioning and reward is less clear. Objectives The current study uses functional magnetic resonance imaging (fMRI) to investigate the role of the eCB system in reward processing in humans by examining the effect of the eCB agonist Δ9-tetrahydrocannabinol (THC) on reward-related brain activity. Methods Eleven healthy males participated in a randomized placebo-controlled pharmacological fMRI study with administration of THC to challenge the eCB system. We compared anticipatory and feedback-related brain activity after placebo and THC, using a monetary incentive delay task. In this task, subjects are notified before each trial whether a correct response is rewarded (“reward trial”) or not (“neutral trial”). Results Subjects showed faster reaction times during reward trials compared to neutral trials, and this effect was not altered by THC. THC induced a widespread attenuation of the brain response to feedback in reward trials but not in neutral trials. Anticipatory brain activity was not affected. Conclusions These results suggest a role for the eCB system in the appreciation of rewards. The involvement of the eCB system in feedback processing may be relevant for disorders in which appreciation of natural rewards may be affected such as addiction

Genome-wide meta-analysis of muscle weakness identifies 15 susceptibility loci in older men and women.

Low muscle strength is an important heritable indicator of poor health linked to morbidity and mortality in older people. In a genome-wide association study meta-analysis of 256,523 Europeans aged 60 years and over from 22 cohorts we identify 15 loci associated with muscle weakness (European Working Group on Sarcopenia in Older People definition: n = 48,596 cases, 18.9% of total), including 12 loci not implicated in previous analyses of continuous measures of grip strength. Loci include genes reportedly involved in autoimmune disease (HLA-DQA1 p = 4 × 10-17), arthritis (GDF5 p = 4 × 10-13), cell cycle control and cancer protection, regulation of transcription, and others involved in the development and maintenance of the musculoskeletal system. Using Mendelian randomization we report possible overlapping causal pathways, including diabetes susceptibility, haematological parameters, and the immune system. We conclude that muscle weakness in older adults has distinct mechanisms from continuous strength, including several pathways considered to be hallmarks of ageing

Analysis of shared heritability in common disorders of the brain

ience, this issue p. eaap8757 Structured Abstract INTRODUCTION Brain disorders may exhibit shared symptoms and substantial epidemiological comorbidity, inciting debate about their etiologic overlap. However, detailed study of phenotypes with different ages of onset, severity, and presentation poses a considerable challenge. Recently developed heritability methods allow us to accurately measure correlation of genome-wide common variant risk between two phenotypes from pools of different individuals and assess how connected they, or at least their genetic risks, are on the genomic level. We used genome-wide association data for 265,218 patients and 784,643 control participants, as well as 17 phenotypes from a total of 1,191,588 individuals, to quantify the degree of overlap for genetic risk factors of 25 common brain disorders. RATIONALE Over the past century, the classification of brain disorders has evolved to reflect the medical and scientific communities' assessments of the presumed root causes of clinical phenomena such as behavioral change, loss of motor function, or alterations of consciousness. Directly observable phenomena (such as the presence of emboli, protein tangles, or unusual electrical activity patterns) generally define and separate neurological disorders from psychiatric disorders. Understanding the genetic underpinnings and categorical distinctions for brain disorders and related phenotypes may inform the search for their biological mechanisms. RESULTS Common variant risk for psychiatric disorders was shown to correlate significantly, especially among attention deficit hyperactivity disorder (ADHD), bipolar disorder, major depressive disorder (MDD), and schizophrenia. By contrast, neurological disorders appear more distinct from one another and from the psychiatric disorders, except for migraine, which was significantly correlated to ADHD, MDD, and Tourette syndrome. We demonstrate that, in the general population, the personality trait neuroticism is significantly correlated with almost every psychiatric disorder and migraine. We also identify significant genetic sharing between disorders and early life cognitive measures (e.g., years of education and college attainment) in the general population, demonstrating positive correlation with several psychiatric disorders (e.g., anorexia nervosa and bipolar disorder) and negative correlation with several neurological phenotypes (e.g., Alzheimer's disease and ischemic stroke), even though the latter are considered to result from specific processes that occur later in life. Extensive simulations were also performed to inform how statistical power, diagnostic misclassification, and phenotypic heterogeneity influence genetic correlations. CONCLUSION The high degree of genetic correlation among many of the psychiatric disorders adds further evidence that their current clinical boundaries do not reflect distinct underlying pathogenic processes, at least on the genetic level. This suggests a deeply interconnected nature for psychiatric disorders, in contrast to neurological disorders, and underscores the need to refine psychiatric diagnostics. Genetically informed analyses may provide important "scaffolding" to support such restructuring of psychiatric nosology, which likely requires incorporating many levels of information. By contrast, we find limited evidence for widespread common genetic risk sharing among neurological disorders or across neurological and psychiatric disorders. We show that both psychiatric and neurological disorders have robust correlations with cognitive and personality measures. Further study is needed to evaluate whether overlapping genetic contributions to psychiatric pathology may influence treatment choices. Ultimately, such developments may pave the way toward reduced heterogeneity and improved diagnosis and treatment of psychiatric disorders