Hypertrophic cardiomyopathy R403Q mutation in rabbit ß-myosin reduces contractile function at the molecular and myofibrillar levels.

In 1990, the Seidmans showed that a single point mutation, R403Q, in the human ß-myosin heavy chain (MHC) of heart muscle caused a particularly malignant form of familial hypertrophic cardiomyopathy (HCM) [Geisterfer-Lowrance AA, et al. (1990) Cell 62:999-1006.]. Since then, more than 300 mutations in the ß-MHC have been reported, and yet there remains a poor understanding of how a single missense mutation in the MYH7 gene can lead to heart disease. Previous studies with a transgenic mouse model showed that the myosin phenotype depended on whether the mutation was in an α- or ß-MHC backbone. This led to the generation of a transgenic rabbit model with the R403Q mutation in a ß-MHC backbone. We find that the in vitro motility of heterodimeric R403Q myosin is markedly reduced, whereas the actin-activated ATPase activity of R403Q subfragment-1 is about the same as myosin from a nontransgenic littermate. Single myofibrils isolated from the ventricles of R403Q transgenic rabbits and analyzed by atomic force microscopy showed reduced rates of force development and relaxation, and achieved a significantly lower steady-state level of isometric force compared with nontransgenic myofibrils. Myofibrils isolated from the soleus gave similar results. The force-velocity relationship determined for R403Q ventricular myofibrils showed a decrease in the velocity of shortening under load, resulting in a diminished power output. We conclude that independent of whether experiments are performed with isolated molecules or with ordered molecules in the native thick filament of a myofibril, there is a loss-of-function induced by the R403Q mutation in ß-cardiac myosin.

Fission yeast myosin Myo2 is down-regulated in actin affinity by light chain phosphorylation.

Studies in fission yeast Schizosaccharomyces pombe have provided the basis for the most advanced models of the dynamics of the cytokinetic contractile ring. Myo2, a class-II myosin, is the major source of tension in the contractile ring, but how Myo2 is anchored and regulated to produce force is poorly understood. To enable more detailed biochemical/biophysical studies, Myo2 was expressed in the baculovirus/Sf9 insect cell system with its two native light chains, Rlc1 and Cdc4. Milligram yields of soluble, unphosphorylated Myo2 were obtained that exhibited high actin-activated ATPase activity and in vitro actin filament motility. The fission yeast specific chaperone Rng3 was thus not required for expression or activity. In contrast to nonmuscle myosins from animal cells that require phosphorylation of the regulatory light chain for activation, phosphorylation of Rlc1 markedly reduced the affinity of Myo2 for actin. Another unusual feature of Myo2 was that, unlike class-II myosins, which generally form bipolar filamentous structures, Myo2 showed no inclination to self-assemble at approximately physiological salt concentrations, as analyzed by sedimentation velocity ultracentrifugation. This lack of assembly supports the hypothesis that clusters of Myo2 depend on interactions at the cell cortex in structural units called nodes for force production during cytokinesis.

What Will My Life Be Like at Age 70? Perspectives of Undergraduate Students in an Aging Course.

The affective domain of learning is an essential component in the professional development of nursing students. Teaching strategies stimulating an emotional response can impact students' attitudes, values, and beliefs. This qualitative study examined the use of a reflective journaling assignment in eliciting perspectives from 142 students about aging. Most students identified the assignment to be a real "eye opener" and perceived older adults in a different light. Students consulted with a grandparent or another older adult while writing the essay, which led to a mutually satisfying connection. Students were most fearful about loss of functional status, being too ill to enjoy activities, and the deaths of loved ones. Students often lack the ability to see patients beyond their current health status because educational programs largely focus on the cognitive domain. Using strategies targeting the affective domain can help students reconsider their values and beliefs toward the older population. [Journal of Gerontological Nursing, 46(4), 48-52.].

Palliative Care in the Management of Patients with Advanced Heart Failure.

Globally, there are 18-million individuals living with heart failure, a disease that is responsible for 12-15 million office visits and 6.5 million inpatient hospitalizations each year. As HF becomes advanced or end-stage, patients often live in a cycle of frequent transitions between care settings, and with unmet needs, including distress from inadequately managed symptoms. Prognostication in patients with heart failure can be challenging due to the unpredictable exacerbating-remitting illness trajectory that is associated with this progressive disease. Recurrent hospitalizations, worsening functional status and refractory symptoms, despite optimal therapies, are among the most salient predictors indicating that patients with advanced heart failure are nearing the end of life. Palliative care is a specialized form of medical care that has been shown to help improve severity of symptoms, facilitate discussions regarding medical decision making/advance care planning, and provide support for patients and their families. Palliative care can be used alongside curative treatments and has been shown to improve patient satisfaction and quality of life. Anorexia-cachexia syndrome, dyspnea, fatigue, pain and depression are among the most common symptoms experienced by patients suffering from advanced heart failure. Palliative care can help alleviate these symptoms and also facilitate conversations about decision making surrounding resuscitation status and use or deactivation of medical devices, such as an implantable-cardioverter-defibrillator (ICD). Clinical practice guidelines from the American College of Cardiology and American Heart Association report that aggressive life-sustaining treatments and therapies should not be utilized in patients with advanced heart failure who have refractory symptoms that are not responding to medical therapy. The focus of care should switch to controlling symptoms, reducing hospital admissions and improving health-related quality of life, which can be supported by the incorporation of palliative care into the treatment plan.

The structure of the actin-smooth muscle myosin motor domain complex in the rigor state.

Myosin-based motility utilizes catalysis of ATP to drive the relative sliding of F-actin and myosin. The earliest detailed model based on cryo-electron microscopy (cryoEM) and X-ray crystallography postulated that higher actin affinity and lever arm movement were coupled to closure of a feature of the myosin head dubbed the actin-binding cleft. Several studies since then using crystallography of myosin-V and cryoEM structures of F-actin bound myosin-I, -II and -V have provided details of this model. The smooth muscle myosin II interaction with F-actin may differ from those for striated and non-muscle myosin II due in part to different lengths of important surface loops. Here we report a ∼6 Šresolution reconstruction of F-actin decorated with the nucleotide-free recombinant smooth muscle myosin-II motor domain (MD) from images recorded using a direct electron detector. Resolution is highest for F-actin and the actin-myosin interface (3.5-4 Å) and lowest (∼6-7 Å) for those parts of the MD at the highest radius. Atomic models built into the F-actin density are quite comparable to those previously reported for rabbit muscle actin and show density from the bound ADP. The atomic model of the MD, is quite similar to a recently published structure of vertebrate non-muscle myosin II bound to F-actin and a crystal structure of nucleotide free myosin-V. Larger differences are observed when compared to the cryoEM structure of F-actin decorated with rabbit skeletal muscle myosin subfragment 1. The differences suggest less closure of the 50 kDa domain in the actin bound skeletal muscle myosin structure.

Opening the door to your nursing potential.

It was only when I started teaching an undergraduate community health course that I became aware of the general lack in knowledge about nursing career options.

Role of the essential light chain in the activation of smooth muscle myosin by regulatory light chain phosphorylation.

The activity of smooth and non-muscle myosin II is regulated by phosphorylation of the regulatory light chain (RLC) at serine 19. The dephosphorylated state of full-length monomeric myosin is characterized by an asymmetric intramolecular head-head interaction that completely inhibits the ATPase activity, accompanied by a hairpin fold of the tail, which prevents filament assembly. Phosphorylation of serine 19 disrupts these head-head interactions by an unknown mechanism. Computational modeling (Tama et al., 2005. J. Mol. Biol. 345, 837-854) suggested that formation of the inhibited state is characterized by both torsional and bending motions about the myosin heavy chain (HC) at a location between the RLC and the essential light chain (ELC). Therefore, altering relative motions between the ELC and the RLC at this locus might disrupt the inhibited state. Based on this hypothesis we have derived an atomic model for the phosphorylated state of the smooth muscle myosin light chain domain (LCD). This model predicts a set of specific interactions between the N-terminal residues of the RLC with both the myosin HC and the ELC. Site directed mutagenesis was used to show that interactions between the phosphorylated N-terminus of the RLC and helix-A of the ELC are required for phosphorylation to activate smooth muscle myosin.

Transgenic mouse α- and ß-cardiac myosins containing the R403Q mutation show isoform-dependent transient kinetic differences.

Familial hypertrophic cardiomyopathy (FHC) is a major cause of sudden cardiac death in young athletes. The discovery in 1990 that a point mutation at residue 403 (R403Q) in the ß-myosin heavy chain (MHC) caused a severe form of FHC was the first of many demonstrations linking FHC to mutations in muscle proteins. A mouse model for FHC has been widely used to study the mechanochemical properties of mutated cardiac myosin, but mouse hearts express α-MHC, whereas the ventricles of larger mammals express predominantly ß-MHC. To address the role of the isoform backbone on function, we generated a transgenic mouse in which the endogenous α-MHC was partially replaced with transgenically encoded ß-MHC or α-MHC. A His6 tag was cloned at the N terminus, along with R403Q, to facilitate isolation of myosin subfragment 1 (S1). Stopped flow kinetics were used to measure the equilibrium constants and rates of nucleotide binding and release for the mouse S1 isoforms bound to actin. For the wild-type isoforms, we found that the affinity of MgADP for α-S1 (100 µM) is ~ 4-fold weaker than for ß-S1 (25 µM). Correspondingly, the MgADP release rate for α-S1 (350 s(-1)) is ~3-fold greater than for ß-S1 (120 s(-1)). Introducing the R403Q mutation caused only a minor reduction in kinetics for ß-S1, but R403Q in α-S1 caused the ADP release rate to increase by 20% (430 s(-1)). These transient kinetic studies on mouse cardiac myosins provide strong evidence that the functional impact of an FHC mutation on myosin depends on the isoform backbone.

Living with advanced heart failure or COPD: experiences and goals of individuals nearing the end of life.

The last phase of life of patients with end-stage heart failure (HF) or chronic obstructive pulmonary disease (COPD) is marked by high symptom burden and uncertainty about the future. Few enroll in hospice, and their preferences for care remain unknown. The purpose of this qualitative study was to describe the experiences and goals for care of patients with end-stage HF and COPD who were recently discharged from the hospital. Forty semi-structured interviews were completed with 20 participants. Despite conditions considered life-threatening by clinicians, participants believed they still had time. They hoped that their illnesses would remain stable, although specific experiences made them think they might be worsening. All expected that their doctors would tell them when their illnesses became life-threatening.

Short of breath and dying: state of the science on opioid agents for the palliation of refractory dyspnea in older adults.

The purpose of this narrative literature review was to describe the state of the science on the effectiveness of opioid medications to palliate dyspnea in older adults with advanced disease. A three-stage critical appraisal process was used to evaluate articles published between 2000-2011 that were retrieved from the CINAHL, Ovid MEDLINE, and PsycINFO databases. Low-dose opioid medication use was associated with statistically significant reductions in dyspnea intensity scores in the majority of studies included in the analysis. Many recent articles on this topic shed light on the importance but underuse of opioid agents to palliate dyspnea, particularly in older adults with advanced chronic illnesses, such as heart failure and chronic obstructive pulmonary disease. ADRA (Assess, Document, Re-assess, Advocate) is a proposed framework that gerontological nurses can use to ensure patients receive adequate symptom management for refractory dyspnea.

Common structural motifs for the regulation of divergent class II myosins.

This minireview focuses on structural studies that have provided insights into our current understanding of thick filament regulation in muscle. We describe how different domains in the myosin molecule interact to produce an inactive "off" state; included are head-head and head-rod interactions, the role of the regulatory light chain, and the significance of the alpha-helical coiled-coil rod in regulation. Several of these interactions have now been visualized in a wide variety of native myosin filaments, testifying to the generality of these structural motifs across the phylogenetic tree.

Withholding Medical Interventions and Ageism During a Pandemic: A Model for Resource Allocation Decision Making.

Decisions surrounding withholding and withdrawing medical interventions are common within the palliative and hospice care community. The unexpected effects of the recent pandemic ignited conversations about scarcity of resources and withholding medical interventions, based on age, among providers with limited expertise in palliative care. Using a case study and literature review, the aim of this article was to examine the best ethical considerations for resource allocation decision making that minimizes the effects of ageism. Public health ethics differs from clinical ethics by giving priority to promoting the greatest good over the protection of individual autonomy. This divide in ethics sheds light on the dangers associated with ageism. Age is often a component within clinical instruments that guide clinicians with allocation decisions. Basing decisions solely on age without evaluating health and functional status is dangerous and further propagates the discriminatory practices that fuel ageism. Previous research identified using ethical principles to guide resource allocation decisions but that may not be enough to protect the rights of older adults. A new model to guide these decisions should include advance directives and goals of care, medical indicators instead of demographics, functionality, transparent medical team, and impact of social determinants of health.

Impact of a Simulation Workshop on Nursing Students' Attitudes Toward Poverty.

BACKGROUND: Poverty is a global issue that negatively affects health outcomes and quality of life. Incorporating simulation in nursing education programs can help students develop a better understanding about poverty. METHOD: A cross-sectional mixed-methods pre- and posttest survey design was used with two cohorts of undergraduate nursing students who participated in a poverty simulation. RESULTS: A convenience sample of 132 students participated in this study. Most of the students reported they had learned something new that would impact the way they will interact with patients affected by poverty. CONCLUSION: To ensure a competent nursing workforce in an ever-changing global health care environment, all nursing students must have a basic understanding about the implications of poverty on health. Nursing education can enhance a 1-day poverty simulation by partnering with local community groups and agencies so that students can actively participate in improving the lives of disadvantaged individuals who are affected by poverty. [J Nurs Educ. 2021;60(8):462-465.].

An Examination and Comparison of Stethoscope Hygiene in Nursing Education Programs.

BACKGROUND: Improper stethoscope hygiene has been found to contribute to the development of health care associated infections, which affects approximately one in every 30 hospitalized patients. Various pathogens have been found on the stethoscopes of health care workers. METHOD: A correlational descriptive design was used to compare stethoscopes from 117 nursing students. Sterile swab samples were obtained from four separate areas of each stethoscope. Samples were plated and incubated for 24 to 48 hours. RESULTS: Bacteria were found on all parts of the stethoscopes from both undergraduate and graduate nursing students, with the earpiece having the highest percentage of contamination. Staphylococcus was the most prevalent microbe found on all four swab sites. CONCLUSION: Educating students about stethoscope hygiene and consistently reinforcing it in practice are essential to reduce the transmission of pathogens in the health care environment. Nurses can model best practice with students and other disciplines to increase the likelihood of adherence. [J Nurs Educ. 2021;60(5):277-280.].

Management of Severe Pain in Terminally Ill Patients at Home: An Evidence-Based Strategy.

The purpose of this article is to describe current evidence-based strategies to manage severe pain in patients living with terminal illnesses. A comprehensive pain assessment is a critical step in the initial development of a pain management plan and for ongoing evaluation of patients' pain. Although we have many effective clinical tools available for pain assessment, they are not always used consistently, which can negatively affect the pain management plan. Home care and hospice nurses need to be consistent in using the tools and documenting the patient's pain level and response to the pain management plan. Patients and caregivers have concerns and fears surrounding medication use, particularly with narcotic analgesics. It is vital that nurses provide thorough patient-centered teaching about medications to help address these concerns. Research has found that nurses who also provided validation to patients and families regarding their concerns, followed by education, were the most effective.

The carboxyl-terminal isoforms of smooth muscle myosin heavy chain determine thick filament assembly properties.

The alternatively spliced SM1 and SM2 smooth muscle myosin heavy chains differ at their respective carboxyl termini by 43 versus 9 unique amino acids. To determine whether these tailpieces affect filament assembly, SM1 and SM2 myosins, the rod region of these myosin isoforms, and a rod with no tailpiece (tailless), were expressed in Sf 9 cells. Paracrystals formed from SM1 and SM2 rod fragments showed different modes of molecular packing, indicating that the tailpieces can influence filament structure. The SM2 rod was less able to assemble into stable filaments than either SM1 or the tailless rods. Expressed full-length SM1 and SM2 myosins showed solubility differences comparable to the rods, establishing the validity of the latter as a model for filament assembly. Formation of homodimers of SM1 and SM2 rods was favored over the heterodimer in cells coinfected with both viruses, compared with mixtures of the two heavy chains renatured in vitro. These results demonstrate for the first time that the smooth muscle myosin tailpieces differentially affect filament assembly, and suggest that homogeneous thick filaments containing SM1 or SM2 myosin could serve distinct functions within smooth muscle cells.

Evidence for an interaction between the SH3 domain and the N-terminal extension of the essential light chain in class II myosins.

The function of the src-homology 3 (SH3) domain in class II myosins, a distinct beta-barrel structure, remains unknown. Here, we provide evidence, using electron cryomicroscopy, in conjunction with light-scattering, fluorescence and kinetic analyses, that the SH3 domain facilitates the binding of the N-terminal extension of the essential light chain isoform (ELC-1) to actin. The 41 residue extension contains four conserved lysine residues followed by a repeating sequence of seven Pro/Ala residues. It is widely believed that the highly charged region interacts with actin, while the Pro/Ala-rich sequence forms a rigid tether that bridges the approximately 9 nm distance between the myosin lever arm and the thin filament. In order to localize the N terminus of ELC in the actomyosin complex, an engineered Cys was reacted with undecagold-maleimide, and the labeled ELC was exchanged into myosin subfragment-1 (S1). Electron cryomicroscopy of S1-bound actin filaments, together with computer-based docking of the skeletal S1 crystal structure into 3D reconstructions, showed a well-defined peak for the gold cluster near the SH3 domain. Given that SH3 domains are known to bind proline-rich ligands, we suggest that the N-terminal extension of ELC interacts with actin and modulates myosin kinetics by binding to the SH3 domain during the ATPase cycle.

Letting go before a death: a concept analysis.

AIM: This paper is a report of a concept analysis of letting go within the context of family caregivers and end-of-life care. BACKGROUND: The term 'letting go' has been used in an informal manner by nurses and other clinicians working with patients and families with terminal illnesses to depict a lack of acceptance of a loved one's impending death. DATA SOURCES: The CINAHL, Ovid Medline and PsychInfo databases were searched for the period of 1995-2007 for literature published in English in peer-reviewed journals from a variety of disciplines, using the specific keywords letting go or to let go. METHODS: The Walker and Avant method of concept analysis was used, and the study was guided by Zerwekh's family caregiving model of core competencies for hospice nurses. RESULTS: Letting go before the death of a loved one involves a shift in thinking in which there is acknowledgement of impending loss without impeding its natural progression. An emotional attachment and recognition that everything has been carried out usually precede the concept, followed by a peaceful death and acknowledgement of change. CONCLUSION: The concept of letting go has been explored in many contexts but the core essence of the awareness and work towards the acceptance of an impending loss appears to be a universal domain. Research is needed to further explore and identify patterns of this phenomenon in family caregivers in the context of death of a loved one.

Students' Knowledge of and Interest in Older Adults: Impact of a Geriatrics Course.

BACKGROUND: The number of older adults living with chronic conditions is steadily increasing, so nurses must be prepared to care for the needs of this population. However, only one third of nursing education programs include a stand-alone geriatrics course. METHOD: A cross-sectional mixed-methods design was used to compare two cohorts of 46 nursing students. Knowledge, attitude, and interest in older adults were examined using an online survey. The control cohort did not complete the geriatric course. RESULTS: No demographic differences were found between groups. Completing the geriatric course was not correlated with having greater aging-related knowledge. Decreased interest in working with the older adult population was found. CONCLUSION: Findings from this cross-sectional pilot study suggest that previous experience with an aging relative was associated with better aging-related knowledge. Further research exploring students' perceptions is needed to understand the relationship between the geriatric course and attitudes toward aging. [J Nurs Educ. 2018;57(2):106-109.].