Comparative effectiveness and healthcare utilization for ambulatory cardiac monitoring strategies in Medicare beneficiaries.

BACKGROUND: Objective data comparing the diagnostic performance of different ambulatory cardiac monitors (ACMs) are lacking. OBJECTIVES: To assess variation in monitoring strategy, clinical outcomes and healthcare utilization in patients undergoing ambulatory monitoring without a pre-existing arrhythmia diagnosis. METHODS: Using the full sample (100%) of Medicare claims data, we performed a retrospective cohort study of diagnostic-naïve patients who received first-time ACM in 2017 to 2018 and evaluated arrhythmia encounter diagnosis at 3-months, repeat ACM testing at 6 months, all-cause 90-day emergency department (ED) and inpatient utilization, and cost of different strategies: Holter; long-term continuous monitor (LTCM); non-continuous, event-based external ambulatory event monitor (AEM); and mobile cardiac telemetry (MCT). We secondarily performed a device-specific analysis by manufacturer, identified from unique claim modifier codes. RESULTS: ACMs were used in 287,789 patients (AEM = 10.3%; Holter = 53.8%; LTCM = 13.3%; MCT = 22.5%). Device-specific analysis showed that compared to Holter, AEM, MCT, or other LTCM manufacturers, a specific LTCM (ZioⓇ XT 14-day patch, iRhythm Technologies, San Francisco, CA) had the highest adjusted odds of diagnosis and lowest adjusted odds of ACM retesting. Findings were consistent for specific arrhythmia diagnoses of ventricular tachycardia, atrioventricular block, and paroxysmal atrial fibrillation. As a category, LTCM was associated with the lowest 1-year incremental health care expenditures (mean Δ$10,159), followed by Holter ($10,755), AEM ($11,462), and MCT ($12,532). CONCLUSIONS: There was large variation in diagnostic monitoring strategy. A specific LTCM was associated with the highest adjusted odds of a new arrhythmia diagnosis and lowest adjusted odds of repeat ACM testing. LTCM as a category had the lowest incremental acute care utilization. Different monitoring strategies may produce different results with respect to diagnosis and care.

A human IgM signals axon outgrowth: coupling lipid raft to microtubules.

Mouse and human IgMs support neurite extension from primary cerebellar granule neurons. In this study using primary hippocampal and cortical neurons, we demonstrate that a recombinant human IgM, rHIgM12, promotes axon outgrowth by coupling membrane domains (lipid rafts) to microtubules. rHIgM12 binds to the surface of neuron and induces clustering of cholesterol and ganglioside GM1. After cell binding and membrane fractionation, rHIgM12 gets segregated into two pools, one associated with lipid raft fractions and the other with the detergent-insoluble cytoskeleton-containing pellet. Membrane-bound rHIgM12 co-localized with microtubules and co-immuno precipitated with ß3-tubulin. rHIgM12-membrane interaction also enhanced the tyrosination of α-tubulin indicating a stabilization of new neurites. When presented as a substrate, rHIgM12 induced axon outgrowth from primary neurons. We now demonstrate that a recombinant human mAb can induce signals in neurons that regulate membrane lipids and microtubule dynamics required for axon extension. We propose that the pentameric structure of the IgM is critical to cross-link membrane lipids and proteins resulting in signaling cascades.

Dissemination of computer-assisted cognitive-behavior therapy for depression in primary care.

Computer-assisted cognitive-behavior therapy (CCBT) for depression in primary care will be evaluated in a trial with 240 patients randomly assigned to CCBT or treatment as usual (TAU). The study will disseminate a therapy method found to be effective in psychiatric settings into primary care - a setting in which there have been significant problems in the delivery of adequate, evidence-based treatment for depression. The study will include a high percentage of disadvantaged (low-income) patients - a population that has been largely ignored in previous research in CCBT. There have been no previous studies of CCBT for depression in primary care that have enrolled large numbers of disadvantaged patients. The form of CCBT used in this study is designed to increase access to effective therapy, provide a cost-effective method, and be a sustainable model for wide-spread use in primary care. In order to deliver therapy in a practical manner that can be replicated in other primary care practices, patients with significant symptoms of depression will receive treatment with an empirically supported computer program that builds cognitive-behavior therapy skills. Support for CCBT will be provided by telephone and/or e-mail contact with a care coordinator (CC) instead of face-to-face treatment with a cognitive-behavior therapist. Outcome will be assessed by measuring CCBT completion rate, comprehension of CBT concepts, and satisfaction with treatment, in addition to ratings of depressive symptoms, negative thoughts, and quality of life. The cost-effectiveness analysis and exploration of possible predictors of outcome should help clinicians, health care organizations, and others plan further dissemination of CCBT in primary care.

Nkx6.1-mediated insulin secretion and ß-cell proliferation is dependent on upregulation of c-Fos.

Understanding the molecular pathways that enhance ß-cell proliferation, survival, and insulin secretion may be useful to improve treatments for diabetes. Nkx6.1 induces proliferation through the Nr4a nuclear receptors, and improves insulin secretion and survival through the peptide hormone VGF. Here we demonstrate that Nkx6.1-mediated upregulation of Nr4a1, Nr4a3, and VGF is dependent on c-Fos expression. c-Fos overexpression results in activation of Nkx6.1 responsive genes and increases ß-cell proliferation, insulin secretion, and cellular survival. c-Fos knockdown impedes Nkx6.1-mediated ß-cell proliferation and insulin secretion. These data demonstrate that c-Fos is critical for Nkx6.1-mediated expansion of functional ß-cell mass.

Remyelination induced by a DNA aptamer in a mouse model of multiple sclerosis.

Multiple sclerosis (MS) is a debilitating inflammatory disease of the central nervous system (CNS) characterized by local destruction of the insulating myelin surrounding neuronal axons. With more than 200 million MS patients worldwide, the absence of treatments that prevent progression or induce repair poses a major challenge. Anti-inflammatory therapies have met with limited success only in preventing relapses. Previous screening of human serum samples revealed natural IgM antibodies that bind oligodendrocytes and promote both cell signaling and remyelination of CNS lesions in an MS model involving chronic infection of susceptible mice by Theiler's encephalomyelitis virus and in the lysolecithin model of focal demyelination. This intriguing result raises the possibility that molecules with binding specificity for oligodendrocytes or myelin components may promote therapeutic remyelination in MS. Because of the size and complexity of IgM antibodies, it is of interest to identify smaller myelin-specific molecules with the ability to promote remyelination in vivo. Here we show that a 40-nucleotide single-stranded DNA aptamer selected for affinity to murine myelin shows this property. This aptamer binds multiple myelin components in vitro. Peritoneal injection of this aptamer results in distribution to CNS tissues and promotes remyelination of CNS lesions in mice infected by Theiler's virus. Interestingly, the selected DNA aptamer contains guanosine-rich sequences predicted to induce folding involving guanosine quartet structures. Relative to monoclonal antibodies, DNA aptamers are small, stable, and non-immunogenic, suggesting new possibilities for MS treatment.

Cellular mechanisms of central nervous system repair by natural autoreactive monoclonal antibodies.

Natural autoreactive monoclonal IgM antibodies have demonstrated potential as therapeutic agents for central nervous system (CNS) disease. These antibodies bind surface antigens on specific CNS cells, activating intracellular repair-promoting signals. IgM antibodies that bind to surface antigens on oligodendrocytes enhanced remyelination in animal models of multiple sclerosis. IgM antibodies that bind to neurons stimulate neurite outgrowth and prevent neuron apoptosis. The neuron-binding IgM antibodies may have utility in CNS axon- or neuron-damaging diseases, such as amyotrophic lateral sclerosis, stroke, spinal cord injury, or secondary progressive multiple sclerosis. Recombinant remyelination-promoting IgM antibodies have been generated for formal toxicology studies and, after Food and Drug Administration approval, a phase 1 clinical trial. Natural autoreactive monoclonal antibodies directed against CNS cells represent novel therapeutic molecules to induce repair of the nervous system.