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Mesenchymal stem cells (MSCs) are well known for their regenerative potential. Despite the fact that the ability of MSCs to proliferate and differentiate has been studied extensively, there still remains much to learn about the signalling mechanisms and pathways which control proliferation and influence differentiation phenotype. In recent years, there has been growing evidence for the utility of non-neuronal cholinergic signalling systems and that acetylcholine (ACh) plays an important, ubiquitous, role in cell-to-cell communication. Indeed, cholinergic signalling is hypothesised to occur in stem cells and ACh synthesis, as well as ACh receptor (AChR) expression, has been identified in several stem cell populations; including MSCs. Furthermore, AChRs have been found to influence MSC regenerative potential. In humans, there are two major classes of AChRs, muscarinic AChRs and nicotinic AChRs, with each class possessing several subtypes or subunits. In this review, the expression and function of AChRs in different types of MSC will be summarised with the aim of highlighting how AChRs play a pivotal role in regulating MSC regenerative function.

Background Globally, attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder that affects children. In 2011, there was an ADHD diagnosis prevalence of around 8% among children (4-17 years) in the US. ADHD-affected children are more prone to physical injuries such as physical trauma, accidental poisoning, burns, etc. This study was aimed to evaluate the association of ADHD with severe injuries, the influence of age and gender on this association, and the impact of ADHD medications on the frequency of such injuries. Methodology This study was conducted in three governmental and three private settings in Aseer region. The files of children who were diagnosed with ADHD in the study settings were reviewed for a 12-month time period. Data were extracted from the medical files using a pre-structured data extraction sheet to avoid errors and inter-rater bias. The extracted data included child gender, age, duration of disease, and injury-related data. A brief questionnaire had been applied to mothers regarding mothers' attitudes towards injuries among their children, adherence to medications, as well as the reasons for non-adherence to medications and clinical visits in a non-adherent group during the clinic visit. Results One hundred and sixty-three children with a diagnosis of ADHD completed the study. The affected children were aged between two and 15 years (mean: 7.8 ± 2.9 years). An exact of 116 (71.2%) children were males. An exact of 70 (42.9%) affected children had trauma. The most-reported traumas were superficial injuries (84.3%), burns (48.6%), fractures (37.1%), deep injuries (31.4%), and broken or lost teeth (28.6%). About 52% of the children were adherent to medications and their clinical visits. Among the non-adherent group, the most reported reasons were parents’ care and attention (20.5%), followed by the COVID-19 pandemic and delay in visits times (16.7%). Regarding mothers' attitudes towards injuries among children with ADHD, 49.1% of the mothers agreed that there is an association between a child with ADHD and being traumatized while 22.7% said there was no relation. Conclusions In our cohort, the majority of the children with ADHD were boys at primary school age. Association of the history of the disease with trauma was not uncommon, and most injuries were not severe, but burns and deep injuries were reported among considered portions.

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