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Biomedical subjects

Elizabeth M McNally

Publications and source records attributed to Elizabeth M McNally.

At least 19 recordsLinked to original sources
PubMed2026

Additive value of polygenic risk and family history for coronary heart disease risk stratification in two diverse US cohorts.

Whether polygenic risk, monogenic familial hypercholesterolemia (FH), and family history (FamHx) are additively informative for coronary heart disease (CHD) risk prediction across self-identified race/ethnicity (SIRE) groups has not been established. In two diverse cohorts-Electronic Medical Records and Genomics (eMERGE) phase IV (eIV; n = 19,348) and All of Us (AoU; n = 239,645)-we quantified the associations of a polygenic risk score (PRSCHD), pathogenic/likely pathogenic variants in genes associated with FH, and FamHx with CHD and evaluated their incremental value when added to the pooled cohort equations (PCEs). CHD was defined as myocardial infarction, unstable angina, or coronary revascularization. We modeled associations with multivariable logistic regression (prevalent CHD in eIV) and Cox proportional hazards (incident CHD in AoU) and characterized predictive performance with the c-statistic and reclassification and decision-curve net benefits across actionable 10-year risk thresholds. The effects of PRSCHD and FamHx were independent and additive in both cohorts and consistent across White, Black, and Latino SIRE groups. In eIV, adding PRSCHD and FamHx to the PCE increased the c-statistic for prevalent CHD from 0.719 to 0.753 (p-diff = 9.1 × 10-3) and reclassified 18.8% of participants at the 7.5% 10-year threshold, yielding approximately 4 additional true-positive CHD identifications per 1,000 screened. Net benefit gains were observed between the 7.5% and 10% thresholds across all three SIRE groups. In conclusion, PRSCHD and FamHx were independently and additively associated with CHD across major SIRE groups in two diverse cohorts in the United States (US), motivating the addition of these factors to clinical risk algorithms.

Humans↗
PubMed2025

Covering medical care costs for participants in the eMERGE Network: Challenges for equity and implementation.

PURPOSE: To investigate the complexities of covering study-recommended medical care costs for individuals (in order to prevent lack of adherence due to financial reasons), which have received little attention. METHODS: We explored the deliberations, decisions, and challenges faced by the Electronic Medical Records and Genomics (eMERGE) Network during the implementation of a genomic research project recommending clinical care based on high-risk results defined largely by polygenic risk scores. Two surveys were disseminated to eMERGE sites: to identify preferences about payment for specific care recommendations (survey 1) and to understand the operational processes of covering medical care costs (survey 2). RESULTS: Paying for a subset of care recommendations for the funded study duration was identified as the most feasible approach for covering medical care costs for participants who received high-risk genomic results. Each eMERGE site, by necessity, used diverse approaches to pay for medical care costs. CONCLUSION: eMERGE researchers balanced competing concerns about bias, equity, study design, regulatory compliance, and cost in designing a unified approach to cover some of the recommended medical care costs in the study. Many implementation challenges were encountered. Findings can inform researchers and regulatory bodies about the implications and complications of covering medical care costs in translational research studies focused on prevention.

Humans↗
PubMed2007

New approaches in the therapy of cardiomyopathy in muscular dystrophy.

Cardiomyopathy is a frequent occurrence in muscular dystrophy, and heart disease in muscular dystrophy can contribute to both morbidity and mortality. A number of novel therapies are being developed for muscular dystrophy, and the efficacy of these therapies for heart disease is unknown. The most common X-linked recessive disease is Duchenne muscular dystrophy (DMD), which arises from defects in the dystrophin gene. Therapy specifically aimed at DMD is reviewed in the context of its projected effect on cardiomyopathy associated with DMD. Additionally, novel therapies are being pursued to treat specifically the cardiomyopathy of DMD. There is substantial genetic heterogeneity underlying the muscular dystrophies, and not all muscular dystrophy patients develop cardiomyopathy. A subset of muscular dystrophies may place patients at significantly greater risk of developing cardiomyopathy and cardiac rhythm disturbances. These disorders are discussed, highlighting recent studies and recommendations for therapy.

Cardiomyopathies↗
PubMed2006

Nuclear sequestration of delta-sarcoglycan disrupts the nuclear localization of lamin A/C and emerin in cardiomyocytes.

Sarcoglycan is a membrane-associated protein complex found at the plasma membrane of cardiomyocytes and skeletal myofibers. Recessive mutations of delta-sarcoglycan that eliminate expression, and therefore function, lead to cardiomyopathy and muscular dystrophy by producing instability of the plasma membrane. A dominant missense mutation in the gene encoding delta-sarcoglycan was previously shown to associate with dilated cardiomyopathy in humans. To investigate the mechanism of dominantly inherited cardiomyopathy, we generated transgenic mice that express the S151A delta-sarcoglycan mutation in the heart using the alpha-myosin heavy-chain gene promoter. Similar to the human delta-sarcoglycan gene mutation, S151A delta-sarcoglycan transgenic mice developed dilated cardiomyopathy at a young age with enhanced lethality. Instead of placement at the plasma membrane, delta-sarcoglycan was found in the nucleus of S151A delta-sarcoglycan cardiomyocytes. Retention of delta-sarcoglycan in the nucleus was accompanied by partial nuclear sequestration of beta- and gamma-sarcoglycan. Additionally, the nuclear-membrane-associated proteins, lamin A/C and emerin, were mislocalized throughout the nucleoplasm. Therefore, the S151A delta-sarcoglycan gene mutation acts in a dominant negative manner to produce trafficking defects that disrupt nuclear localization of lamin A/C and emerin, thus linking together two common mechanisms of inherited cardiomyopathy.

Animals↗
PubMed2006

Phospholamban R14 deletion results in late-onset, mild, hereditary dilated cardiomyopathy.

OBJECTIVES: The purpose of this research was to determine the phenotypic spectrum associated with phospholamban gene (PLN) mutations. BACKGROUND: Inheritance contributes to the development of dilated cardiomyopathy. Mutations in the gene encoding PLN have been associated with dilated cardiomyopathy characterized by early onset and the presence of lethal ventricular arrhythmias. METHODS: We screened a cohort of 260 unrelated dilated cardiomyopathy patients from a tertiary care referral center for mutations in the PLN gene. RESULTS: Family history of cardiomyopathy was present in approximately one-half the individuals in this cohort. We identified 1 family with a deletion of arginine 14 in the PLN. Interestingly, unlike other individuals reported with the identical PLN mutation, these individuals were not diagnosed with dilated cardiomyopathy until their seventh decade when they were only mildly symptomatic with congestive heart failure. CONCLUSIONS: The identical PLN mutation can be associated with both mild and severe forms of dilated cardiomyopathy. Additionally, PLN mutations should be considered in late onset cardiomyopathy. (Genetics of Cardiovascular and Neuromuscular Disease; http://www.clinicaltrials.gov/ct/show/NCT00138931?order=1; NCT00138931)

Age of Onset↗
PubMed2006

Genetic modifiers of muscular dystrophy: implications for therapy.

The genetic understanding of the muscular dystrophies has advanced considerably in the last two decades. Over 25 different individual genes are now known to produce muscular dystrophy, and many different "private" mutations have been described for each individual muscular dystrophy gene. For the more common forms of muscular dystrophy, phenotypic variability can be explained by precise mutations. However, for many genetic mutations, the presence of the identical mutation is associated with marked phenotypic range that affects muscle function as well as cardiac function. The explanation for phenotype variability in the muscular dystrophies is only now being explored. The availability of genetically engineered animal models has allowed the generation of single mutations on the background of highly inbred strain. Phenotypic variation that is altered by genetic background argues for the presence of genetic modifier loci that can ameliorate or enhance aspects of the dystrophic phenotype. A number of individual genes have been implicated as modifiers of muscular dystrophy by studies in genetically engineered mouse models of muscular dystrophy. The value of these genes and products is that the pathways identified through these experiments may be exploited for therapy.

Animals↗
PubMed2006

Spontaneous coronary vasospasm in KATP mutant mice arises from a smooth muscle-extrinsic process.

In the vasculature, ATP-sensitive potassium channels (KATP) channels regulate vascular tone. Mice with targeted gene disruptions of KATP subunits expressed in vascular smooth muscle develop spontaneous coronary vascular spasm and sudden death. From these models, it was hypothesized that the loss of KATP channel activity in arterial vascular smooth muscle was responsible for coronary artery spasm. We now tested this hypothesis using a transgenic strategy where the full-length sulfonylurea receptor containing exon 40 was expressed under the control of a smooth muscle-specific SM22alpha promoter. Two transgenic founder lines were generated and independently bred to sulfonylurea receptor 2 (SUR2) null mice to generate mice that restored expression of KATP channels in vascular smooth muscle. Transgenic expression of the sulfonylurea receptor in vascular smooth muscle cells was confirmed by detecting mRNA and protein from the transgene. Functional restoration was determined by recording pinacidil-based KATP current by whole cell voltage clamping of isolated aortic vascular smooth muscle cells isolated from the transgenic restored mice. Despite successful restoration of KATP channels in vascular smooth muscle, transgene-restored SUR2 null mice continued to display frequent episodes of spontaneous ST segment elevation, identical to the phenotype seen in SUR2 null mice. As in SUR2 null mice, ST segment elevation was frequently followed by atrioventricular heart block. ST segment elevation and coronary perfusion pressure in the restored mice did not differ significantly between transgene-negative and transgene-positive SUR2 null mice. We conclude that spontaneous coronary vasospasm and sudden death in SUR2 null mice arises from a coronary artery vascular smooth muscle-extrinsic process.

ATP-Binding Cassette Transporters↗
PubMed2006

Age-dependent effect of myostatin blockade on disease severity in a murine model of limb-girdle muscular dystrophy.

Myostatin (MSTN) is a muscle-specific secreted peptide that functions to limit muscle growth through an autocrine regulatory feedback loop. Loss of MSTN activity in cattle, mice, and humans leads to a profound phenotype of muscle overgrowth, associated with more and larger fibers and enhanced regenerative capacity. Deletion of MSTN in the mdx mouse model of Duchenne muscular dystrophy enhances muscle mass and reduces disease severity. In contrast, loss of MSTN activity in the dyW/dyW mouse model of laminin-deficient congenital muscular dystrophy, a much more severe and lethal disease model, does not improve all aspects of muscle pathology. Here we examined disease severity associated with myostatin (mstn-/-) deletion in mice nullizygous for delta-sarcoglycan (scgd-/-), a model of limb-girdle muscular dystrophy. Early loss of MSTN activity achieved either by monoclonal antibody administration or by gene deletion each improved muscle mass, regeneration, and reduced fibrosis in scgd-/- mice. However, antibody-mediated inhibition of MSTN in late-stage dystrophic scgd-/- mice did not improve disease. These findings suggest that MSTN inhibition may benefit muscular dystrophy when instituted early or if disease is relatively mild but that MSTN inhibition in severely affected or late-stage disease may be ineffective.

Aging↗
PubMed2005

Normal myoblast fusion requires myoferlin.

Muscle growth occurs during embryonic development and continues in adult life as regeneration. During embryonic muscle growth and regeneration in mature muscle, singly nucleated myoblasts fuse to each other to form myotubes. In muscle growth, singly nucleated myoblasts can also fuse to existing large, syncytial myofibers as a mechanism of increasing muscle mass without increasing myofiber number. Myoblast fusion requires the alignment and fusion of two apposed lipid bilayers. The repair of muscle plasma membrane disruptions also relies on the fusion of two apposed lipid bilayers. The protein dysferlin, the product of the Limb Girdle Muscular Dystrophy type 2 locus, has been shown to be necessary for efficient, calcium-sensitive, membrane resealing. We now show that the related protein myoferlin is highly expressed in myoblasts undergoing fusion, and is expressed at the site of myoblasts fusing to myotubes. Like dysferlin, we found that myoferlin binds phospholipids in a calcium-sensitive manner that requires the first C2A domain. We generated mice with a null allele of myoferlin. Myoferlin null myoblasts undergo initial fusion events, but they form large myotubes less efficiently in vitro, consistent with a defect in a later stage of myogenesis. In vivo, myoferlin null mice have smaller muscles than controls do, and myoferlin null muscle lacks large diameter myofibers. Additionally, myoferlin null muscle does not regenerate as well as wild-type muscle does, and instead displays a dystrophic phenotype. These data support a role for myoferlin in the maturation of myotubes and the formation of large myotubes that arise from the fusion of myoblasts to multinucleate myotubes.

Animals↗
PubMed2005

Nesprin-1alpha contributes to the targeting of mAKAP to the cardiac myocyte nuclear envelope.

Muscle A-kinase anchoring protein (mAKAP) is a scaffold protein found principally at the nuclear envelope of striated myocytes. mAKAP maintains a complex consisting of multiple signal transduction molecules including the cAMP-dependent protein kinase A, the ryanodine receptor calcium release channel, phosphodiesterase type 4D3, and protein phosphatase 2A. By an unknown mechanism, a domain containing spectrin repeats is responsible for targeting mAKAP to the nuclear envelope. We now demonstrate that the integral membrane protein nesprin-1alpha serves as a receptor for mAKAP on the nuclear envelope in cardiac myocytes. Nesprin-1alpha is inserted into the nuclear envelope by a conserved, C-terminal, klarsicht-related transmembrane domain and forms homodimers by the binding of an amino-terminal spectrin repeat domain. Through the direct binding of the nesprin-1alpha amino-terminal dimerization domain to the third mAKAP spectrin repeat, nesprin-1alpha targets mAKAP to the nuclear envelope. In turn, overexpression of these spectrin repeat domains in myocytes can displace mAKAP from nesprin-1alpha.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2005

The interaction of coronary tone and cardiac fibrosis.

Regulation of coronary vascular tone is critical for proper perfusion and function of the myocardium. Many disease processes result in compromised regulation of coronary vascular tone and impaired myocardial perfusion. A common result of coronary vascular dysfunction is the development of areas of replacement fibrosis within the myocardium and surrounding the vasculature. Both intravascular processes, such as coronary atherosclerosis and endothelial dysfunction, and extravascular processes, including compromised myocardial metabolism, hormone excesses, and altered local signaling, may result in coronary vascular dysregulation. Coronary occlusion events, in turn, lead to myocardial damage and the activation of inflammatory cells and fibroblasts. The role of fibroblasts in regulating myocardial fibrosis and the contribution of myofibroblasts, cells that have limited contractile potential while retaining many of the extracellular matrix regulating processes of the fibroblast, may also contribute to the development of myocardial disease. In this review we examine the recent literature on myocardial fibrosis and myofibroblast activity, highlighting the effects of several classes of cardiovascular agents on the remodeling process.

Animals↗
PubMed2005

Genetic background influences muscular dystrophy.

Mutations in the genes encoding dystrophin and its associated proteins, the sarcoglycans, lead to muscular dystrophy in humans and in mouse models. In the presence of identical gene mutations, the muscular dystrophy phenotype can be highly variable. Using a mouse model of limb girdle muscular dystrophy engineered with a null allele of gamma-sarcoglycan, we bred the identical gamma-sarcoglycan mutation into four different genetic backgrounds. We found that the gamma-sarcoglycan mutation is least severe in the129SV/J (129) strain and most severe on the DBA 2J JAX (DBA) strain using quantitative measures of Evan's blue dye uptake, as a marker of membrane permeability defects, and hydroxyproline content, as a marker of fibrosis. In addition we show that the DBA mice are most severely affected regardless of gender and age. The enhanced phenotype observed in the DBA strain was not caused by exercise as the DBA mice scored the lowest in a voluntary activity test. The milder phenotype seen in the 129SV/J and C57B6/J strains suggests that these backgrounds contain modifier loci that partially suppress the muscular dystrophy phenotype. Identification of these modifier genes and the associated pathways may lead to novel therapeutic strategies.

Animals↗
PubMed2005

Bacillus anthracis edema toxin causes extensive tissue lesions and rapid lethality in mice.

Bacillus anthracis edema toxin (ET), an adenylyl cyclase, is an important virulence factor that contributes to anthrax disease. The role of ET in anthrax pathogenesis is, however, poorly understood. Previous studies using crude toxin preparations associated ET with subcutaneous edema, and ET-deficient strains of B. anthracis showed a reduction in virulence. We report the first comprehensive study of ET-induced pathology in an animal model. Highly purified ET caused death in BALB/cJ mice at lower doses and more rapidly than previously seen with the other major B. anthracis virulence factor, lethal toxin. Observations of gross pathology showed intestinal intralumenal fluid accumulation followed by focal hemorrhaging of the ileum and adrenal glands. Histopathological analyses of timed tissue harvests revealed lesions in several tissues including adrenal glands, lymphoid organs, bone, bone marrow, gastrointestinal mucosa, heart, and kidneys. Concomitant blood chemistry analyses supported the induction of tissue damage. Several cytokines increased after ET administration, including granulocyte colony-stimulating factor, eotaxin, keratinocyte-derived cytokine, MCP-1/JE, interleukin-6, interleukin-10, and interleukin-1beta. Physiological measurements also revealed a concurrent hypotension and bradycardia. These studies detail the extensive pathological lesions caused by ET and suggest that it causes death due to multiorgan failure.

Adenylyl Cyclases↗
PubMed2005

Therapy insight: cardiovascular complications associated with muscular dystrophies.

The muscular dystrophies are commonly associated with cardiovascular complications, including cardiomyopathy and cardiac arrhythmias. These complications are caused by intrinsic defects in cardiomyocyte and cardiac conduction system function, and by the presence of severe skeletal muscle disease, which also contributes to cardiac dysfunction. Unlike the skeletal muscle degenerative process, for which treatment options are currently limited, therapy is available for the cardiovascular complications that accompany muscular dystrophy. New therapies for skeletal muscle degeneration are moving into clinical trials and, ultimately, into clinical practice. These therapies are expected to also improve the cardiac function, longevity and wellbeing of muscular dystrophy patients.

Cardiovascular Diseases↗
PubMed2004

Genetic compensation for sarcoglycan loss by integrin alpha7beta1 in muscle.

Disruption of the sarcoglycan complex leads to muscle membrane instability and muscular dystrophy in humans and mice. Through the dystrophin glycoprotein complex, sarcoglycan participates in connecting the internal cytoskeleton to the membrane and the extracellular matrix. Integrin alpha7beta1 is also a transmembrane protein of skeletal and cardiac muscle that similarly links the cytoskeleton to the extracellular matrix. Mice lacking integrin alpha7 develop mild muscle degeneration, while sarcoglycan mutant mice display overt muscle degeneration and muscular dystrophy. In sarcoglycan-deficient muscle, integrin alpha7 protein was upregulated at the plasma membrane. To ascertain whether integrin alpha7 upregulation compensates for the loss of the transmembrane sarcoglycan linkage in sarcoglycan-deficient muscle, we generated mice lacking both integrin alpha7 and gamma-sarcoglycan (gxi). These double-mutant gxi mice exhibit profound, rapid muscle degeneration leading to death before one month of age consistent with a weakened cellular attachment to the extracellular matrix. The regenerative capacity of gxi muscle was intact with increased embryonic myosin heavy chain expression, myofiber central nucleation and normal in vivo myoblast differentiation. Therefore, upregulation of integrin alpha7beta1 compensates as a transmembrane muscle cell attachment for sarcoglycan consistent with overlapping roles for sarcoglycan and integrins in mediating cytoskeletal-membrane-extracellular matrix interaction.

Animals↗