Allele-specific differences in ryanodine receptor 1 mRNA expression levels may contribute to phenotypic variability in malignant hyperthermia

<p>Abstract</p> <p>Background</p> <p>Malignant hyperthermia (MH) is a dominantly inherited skeletal muscle disorder that can cause a fatal hypermetabolic reaction to general anaesthetics. The primary locus of MH (MHS1 locus) in humans is linked to chromosome 19q13.1, the position of the gene encoding the ryanodine receptor skeletal muscle calcium release channel (RyR1).</p> <p>Methods</p> <p>In this study, an inexpensive allele-specific PCR (AS-PCR) assay was designed that allowed the relative quantification of the two RyR1 transcripts in heterozygous samples found to be susceptible to MH (MHS). Allele-specific differences in RyR1 expression levels can provide insight into the observed variable penetrance and variations in MH phenotypes between individuals. The presence/absence of the H4833Y mutation in <it>RYR</it>1 transcripts was employed as a marker that allowed discrimination between the two alleles.</p> <p>Results</p> <p>In four skeletal muscle samples and two lymphoblastoid cell lines (LCLs) from different MHS patients, the wild type allele was found to be expressed at higher levels than the mutant RyR1 allele. For both LCLs, the ratios between the wild type and mutant <it>RYR</it>1 alleles did not change after different incubation times with actinomycin D. This suggests that there are no allele-specific differences in RyR1 mRNA stability, at least in these cells.</p> <p>Conclusion</p> <p>The data presented here revealed for the first time allele-specific differences in <it>RYR</it>1 mRNA expression levels in heterozygous MHS samples, and can at least in part contribute to the observed variable penetrance and variations in MH clinical phenotypes.</p

Storytelling as 'unorthodox' agency:negotiating the 2012 family immigration rules (United Kingdom)

This article attends to the lived experience of binational families subject to the 2012 family immigration rules (FIR). It seeks to enrich the pre-existing discussions of family migration within the European Union (EU) and the United Kingdom, focusing on the ‘micro-political’ experiences of those whose lives have been adversely affected by their introduction. It draws on the life writings of binational families, suggesting that a micro-political focus reveals an ongoing neuropolitical experience that traditional accounts of moral agency are ill-equipped to negotiate. The article suggests an unorthodox interpretation of agency premised on storytelling, while probing the tensions that emerge when this lived experience is framed in such a manner. It concludes by positing a series of questions relating to the value of a neuropolitical labelling of the subject and suggests a need to further engage with traumatic interpretations of harm at the intersection of citizenship rights and mobility rights

Calcium Homeostasis in Myogenic Differentiation Factor 1 (MyoD)-Transformed, Virally-Transduced, Skin-Derived Equine Myotubes

Dysfunctional skeletal muscle calcium homeostasis plays a central role in the pathophysiology of several human and animal skeletal muscle disorders, in particular, genetic disorders associated with ryanodine receptor 1 (RYR1) mutations, such as malignant hyperthermia, central core disease, multiminicore disease and certain centronuclear myopathies. In addition, aberrant skeletal muscle calcium handling is believed to play a pivotal role in the highly prevalent disorder of Thoroughbred racehorses, known as Recurrent Exertional Rhabdomyolysis. Traditionally, such defects were studied in human and equine subjects by examining the contractile responses of biopsied muscle strips exposed to caffeine, a potent RYR1 agonist. However, this test is not widely available and, due to its invasive nature, is potentially less suitable for valuable animals in training or in the human paediatric setting. Furthermore, increasingly, RYR1 gene polymorphisms (of unknown pathogenicity and significance) are being identified through next generation sequencing projects. Consequently, we have investigated a less invasive test that can be used to study calcium homeostasis in cultured, skin-derived fibroblasts that are converted to the muscle lineage by viral transduction with a MyoD (myogenic differentiation 1) transgene. Similar models have been utilised to examine calcium homeostasis in human patient cells, however, to date, there has been no detailed assessment of the cells’ calcium homeostasis, and in particular, the responses to agonists and antagonists of RYR1. Here we describe experiments conducted to assess calcium handling of the cells and examine responses to treatment with dantrolene, a drug commonly used for prophylaxis of recurrent exertional rhabdomyolysis in horses and malignant hyperthermia in humans

A Double Mutation of the Ryanodine Receptor Type 1 Gene in a Malignant Hyperthermia Family with Multiminicore Myopathy

Background and PurposeᄏAt least 100 Ryanodine receptor type 1 (RYR1) mutations associated with malignant hyperthermia (MH) and central core disease (CCD) have been identified, but 2 RYR1 mutations accompanying multiminicore myopathy in an MH and/or CCD family have been reported only rarely. MethodsᄏFifty-three members of a large MH family were investigated with clinical, histopathologic, RYR1 mutation, and haplotyping studies. Blood creatine kinase (CK) and myoglobin levels were also measured where possible. ResultsᄏSequencing of the entire RYR1 coding region identified a double RYR1 mutation (R2435H and A4295V) in MH/CCD regions 2 and 3. Haplotyping analysis revealed that the two missense heterozygous mutations (c.7304G>A and c.12891C>T) were always present on a common haplotype allele, and were closely cosegregated with histological multiminicores and elevated serum CK. All the subjects with the double mutation showed elevated serum CK and myoglobin, and the obtained muscle biopsy samples showed multiminicore lesions, but only two family members presented a late-onset, slowly progressive myopathy. ConclusionsᄏWe found multiminicore myopathy with clinical and histological variability in a large MH family with an unusual double RYR1 mutation, including a typical CCD-causing known mutant. These results suggest that multiminicore lesions are associated with the presence of more than two mutations in the RYR1 gene.ope

Adapting and evaluating a tree of life group for women with learning disabilities

Background: This study describes how a specific narrative therapy approach called‘the tree of life’ was adapted to run a group for women with learning disabilities. Thegroup consisted of four participants and ran for five consecutive weeks.Materials and Methods: Participants each constructed a tree to represent their livesand presented their tree to the group who responded with positive feedback andaffirming statements. This led to discussion about overcoming the storms of life anda celebration of the journey the group had been through together.Key Results: Although no change was found on quantitative measures of well-beingand self-esteem, participants reported benefitting from the peer support and socialconnectedness that the group offered, particularly in relation to themes of loss andchange in their lives.Conclusions: ‘The tree of life’ approach has potential value as an intervention forpeople with learning disabilities. The benefits and challenges of this approach within the context of working with people with learning disabilities are discussed

Multi-minicore Disease

Multi-minicore Disease (MmD) is a recessively inherited neuromuscular disorder characterized by multiple cores on muscle biopsy and clinical features of a congenital myopathy. Prevalence is unknown. Marked clinical variability corresponds to genetic heterogeneity: the most instantly recognizable classic phenotype characterized by spinal rigidity, early scoliosis and respiratory impairment is due to recessive mutations in the selenoprotein N (SEPN1) gene, whereas recessive mutations in the skeletal muscle ryanodine receptor (RYR1) gene have been associated with a wider range of clinical features comprising external ophthalmoplegia, distal weakness and wasting or predominant hip girdle involvement resembling central core disease (CCD). In the latter forms, there may also be a histopathologic continuum with CCD due to dominant RYR1 mutations, reflecting the common genetic background. Pathogenetic mechanisms of RYR1-related MmD are currently not well understood, but likely to involve altered excitability and/or changes in calcium homeoestasis; calcium-binding motifs within the selenoprotein N protein also suggest a possible role in calcium handling. The diagnosis of MmD is based on the presence of suggestive clinical features and multiple cores on muscle biopsy; muscle MRI may aid genetic testing as patterns of selective muscle involvement are distinct depending on the genetic background. Mutational analysis of the RYR1 or the SEPN1 gene may provide genetic confirmation of the diagnosis. Management is mainly supportive and has to address the risk of marked respiratory impairment in SEPN1-related MmD and the possibility of malignant hyperthermia susceptibility in RYR1-related forms. In the majority of patients, weakness is static or only slowly progressive, with the degree of respiratory impairment being the most important prognostic factor

Exploring the effectiveness of the Tree of Life in promoting the therapeutic growth of refugee women living with HIV

The current study aimed to understand the experiences of refugee women living with HIV as they participated in the Tree of Life (ToL), a group-based narrative technique. A qualitative case study methodology was used. Five African refugee women took part in the study. The ToL consisted of seven two-hourly sessions conducted on weekly basis. Further, participants completed a feedback form after each session, and they were individually interviewed on completion of the ToL. The researchers kept detailed field notes. The data indicated that participants were motivated to attend the intervention in order to overcome their psychological distress, isolation and negative thoughts associated with their situation. Participants found the intervention beneficial. In a safe and supportive setting, and through the art making process, they were able to reflect on their painful past and current issues associated with their migratory stressors and with living with HIV. They identified personal strengths and qualities that enabled them to cope and build their resilience. The art making process and the discussion of the tree empowered them to re-author their life narratives. Finally, they related to each other and they developed a sense of connectedness. The findings indicate the Tree of Life as a promising technique for use with refugees living with HIV. Implications and future directions are discussed

Malignant hyperthermia

Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle that presents as a hypermetabolic response to potent volatile anesthetic gases such as halothane, sevoflurane, desflurane and the depolarizing muscle relaxant succinylcholine, and rarely, in humans, to stresses such as vigorous exercise and heat. The incidence of MH reactions ranges from 1:5,000 to 1:50,000–100,000 anesthesias. However, the prevalence of the genetic abnormalities may be as great as one in 3,000 individuals. MH affects humans, certain pig breeds, dogs, horses, and probably other animals. The classic signs of MH include hyperthermia to marked degree, tachycardia, tachypnea, increased carbon dioxide production, increased oxygen consumption, acidosis, muscle rigidity, and rhabdomyolysis, all related to a hypermetabolic response. The syndrome is likely to be fatal if untreated. Early recognition of the signs of MH, specifically elevation of end-expired carbon dioxide, provides the clinical diagnostic clues. In humans the syndrome is inherited in autosomal dominant pattern, while in pigs in autosomal recessive. The pathophysiologic changes of MH are due to uncontrolled rise of myoplasmic calcium, which activates biochemical processes related to muscle activation. Due to ATP depletion, the muscle membrane integrity is compromised leading to hyperkalemia and rhabdomyolysis. In most cases, the syndrome is caused by a defect in the ryanodine receptor. Over 90 mutations have been identified in the RYR-1 gene located on chromosome 19q13.1, and at least 25 are causal for MH. Diagnostic testing relies on assessing the in vitro contracture response of biopsied muscle to halothane, caffeine, and other drugs. Elucidation of the genetic changes has led to the introduction, on a limited basis so far, of genetic testing for susceptibility to MH. As the sensitivity of genetic testing increases, molecular genetics will be used for identifying those at risk with greater frequency. Dantrolene sodium is a specific antagonist of the pathophysiologic changes of MH and should be available wherever general anesthesia is administered. Thanks to the dramatic progress in understanding the clinical manifestation and pathophysiology of the syndrome, the mortality from MH has dropped from over 80% thirty years ago to less than 5%

Anesthesia advanced circulatory life support

The constellation of advanced cardiac life support (ACLS) events, such as gas embolism, local anesthetic overdose, and spinal bradycardia, in the perioperative setting differs from events in the pre-hospital arena. As a result, modification of traditional ACLS protocols allows for more specific etiology-based resuscitation. Perioperative arrests are both uncommon and heterogeneous and have not been described or studied to the same extent as cardiac arrest in the community. These crises are usually witnessed, frequently anticipated, and involve a rescuer physician with knowledge of the patient's comorbidities and coexisting anesthetic or surgically related pathophysiology. When the health care provider identifies the probable cause of arrest, the practitioner has the ability to initiate medical management rapidly. Recommendations for management must be predicated on expert opinion and physiological understanding rather than on the standards currently being used in the generation of ACLS protocols in the community. Adapting ACLS algorithms and considering the differential diagnoses of these perioperative events may prevent cardiac arrest