Hexokinase 1 cellular localization regulates the metabolic fate of glucose.

The product of hexokinase (HK) enzymes, glucose-6-phosphate, can be metabolized through glycolysis or directed to alternative metabolic routes, such as the pentose phosphate pathway (PPP) to generate anabolic intermediates. HK1 contains an N-terminal mitochondrial binding domain (MBD), but its physiologic significance remains unclear. To elucidate the effect of HK1 mitochondrial dissociation on cellular metabolism, we generated mice lacking the HK1 MBD (ΔE1HK1). These mice produced a hyper-inflammatory response when challenged with lipopolysaccharide. Additionally, there was decreased glucose flux below the level of GAPDH and increased upstream flux through the PPP. The glycolytic block below GAPDH is mediated by the binding of cytosolic HK1 with S100A8/A9, resulting in GAPDH nitrosylation through iNOS. Additionally, human and mouse macrophages from conditions of low-grade inflammation, such as aging and diabetes, displayed increased cytosolic HK1 and reduced GAPDH activity. Our data indicate that HK1 mitochondrial binding alters glucose metabolism through regulation of GAPDH.

In vivo clonal analysis reveals self-renewing and multipotent adult neural stem cell characteristics.

Neurogenesis and gliogenesis continue in discrete regions of the adult mammalian brain. A fundamental question remains whether cell genesis occurs from distinct lineage-restricted progenitors or from self-renewing and multipotent neural stem cells in the adult brain. Here, we developed a genetic marking strategy for lineage tracing of individual, quiescent, and nestin-expressing radial glia-like (RGL) precursors in the adult mouse dentate gyrus. Clonal analysis identified multiple modes of RGL activation, including asymmetric and symmetric self-renewal. Long-term lineage tracing in vivo revealed a significant percentage of clones that contained RGL(s), neurons, and astrocytes, indicating capacity of individual RGLs for both self-renewal and multilineage differentiation. Furthermore, conditional Pten deletion in RGLs initially promotes their activation and symmetric self-renewal but ultimately leads to terminal astrocytic differentiation and RGL depletion in the adult hippocampus. Our study identifies RGLs as self-renewing and multipotent neural stem cells and provides novel insights into in vivo properties of adult neural stem cells.

DNA Damage and Nuclear Morphological Changes in Cardiac Hypertrophy Are Mediated by SNRK Through Actin Depolymerization.

BACKGROUND: Proper nuclear organization is critical for cardiomyocyte function, because global structural remodeling of nuclear morphology and chromatin structure underpins the development and progression of cardiovascular disease. Previous reports have implicated a role for DNA damage in cardiac hypertrophy; however, the mechanism for this process is not well delineated. AMPK (AMP-activated protein kinase) family of proteins regulates metabolism and DNA damage response (DDR). Here, we examine whether a member of this family, SNRK (SNF1-related kinase), which plays a role in cardiac metabolism, is also involved in hypertrophic remodeling through changes in DDR and structural properties of the nucleus. METHODS: We subjected cardiac-specific Snrk-/- mice to transaortic banding to assess the effect on cardiac function and DDR. In parallel, we modulated SNRK in vitro and assessed its effects on DDR and nuclear parameters. We also used phosphoproteomics to identify novel proteins that are phosphorylated by SNRK. Last, coimmunoprecipitation was used to verify Destrin (DSTN) as the binding partner of SNRK that modulates its effects on the nucleus and DDR. RESULTS: Cardiac-specific Snrk-/- mice display worse cardiac function and cardiac hypertrophy in response to transaortic banding, and an increase in DDR marker pH2AX (phospho-histone 2AX) in their hearts. In addition, in vitro Snrk knockdown results in increased DNA damage and chromatin compaction, along with alterations in nuclear flatness and 3-dimensional volume. Phosphoproteomic studies identified a novel SNRK target, DSTN, a member of F-actin depolymerizing factor proteins that directly bind to and depolymerize F-actin. SNRK binds to DSTN, and DSTN downregulation reverses excess DNA damage and changes in nuclear parameters, in addition to cellular hypertrophy, with SNRK knockdown. We also demonstrate that SNRK knockdown promotes excessive actin depolymerization, measured by the increased ratio of G-actin to F-actin. Last, jasplakinolide, a pharmacological stabilizer of F-actin, rescues the increased DNA damage and aberrant nuclear morphology in SNRK-downregulated cells. CONCLUSIONS: These results indicate that SNRK is a key player in cardiac hypertrophy and DNA damage through its interaction with DSTN. This interaction fine-tunes actin polymerization to reduce DDR and maintain proper cardiomyocyte nuclear shape and morphology.

mRNA-binding protein tristetraprolin is essential for cardiac response to iron deficiency by regulating mitochondrial function.

Cells respond to iron deficiency by activating iron-regulatory proteins to increase cellular iron uptake and availability. However, it is not clear how cells adapt to conditions when cellular iron uptake does not fully match iron demand. Here, we show that the mRNA-binding protein tristetraprolin (TTP) is induced by iron deficiency and degrades mRNAs of mitochondrial Fe/S-cluster-containing proteins, specifically Ndufs1 in complex I and Uqcrfs1 in complex III, to match the decrease in Fe/S-cluster availability. In the absence of TTP, Uqcrfs1 levels are not decreased in iron deficiency, resulting in nonfunctional complex III, electron leakage, and oxidative damage. Mice with deletion of Ttp display cardiac dysfunction with iron deficiency, demonstrating that TTP is necessary for maintaining cardiac function in the setting of low cellular iron. Altogether, our results describe a pathway that is activated in iron deficiency to regulate mitochondrial function to match the availability of Fe/S clusters.

Expanding Health Information Exchange Improves Identification of Frequent Emergency Department Users.

STUDY OBJECTIVE: Frequent emergency department (ED) users are of interest to policymakers and hospitals. The objective of this study is to examine the effect of health information exchange size on the identification of frequent ED users. METHODS: We retrospectively analyzed data from Healthix, a health information exchange in New York that previously included 10 hospitals and then grew to 31 hospitals. We divided patients into 3 cohorts: high-frequency ED users with 4 or more visits in any 30-day period, medium-frequency ED users with 4 or more visits in any year, and infrequent ED users with fewer than 4 visits in any year. For both the smaller (10-hospital) and larger (31-hospital) health information exchanges, we compared the identification rate of frequent ED users that was based on hospital-specific data with the corresponding rates that were based on health information exchange data. RESULTS: The smaller health information exchange (n=1,696,279 unique ED patients) identified 11.4% more high-frequency users (33,467 versus 30,057) and 9.5% more medium-frequency users (109,497 versus 100,014) than the hospital-specific data. The larger health information exchange (n=3,684,999) identified 19.6% more high-frequency patients (52,727 versus 44,079) and 18.2% more medium-frequency patients (222,574 versus 192,541) than the hospital-specific data. Expanding from the smaller health information exchange to the larger one, we found an absolute increase of 8.2% and 8.7% identified high- and medium-frequency users, respectively. CONCLUSION: Increasing health information exchange size more accurately reflects how patients access EDs and ultimately improves not only the total number of identified frequent ED users but also their identification rate.

Bouncing Back Elsewhere: Multilevel Analysis of Return Visits to the Same or a Different Hospital After Initial Emergency Department Presentation.

STUDY OBJECTIVE: Analyses of 72-hour emergency department (ED) return visits are frequently used for quality assurance purposes and have been proposed as a means of measuring provider performance. These analyses have traditionally examined only patients returning to the same hospital as the initial visit. We use a health information exchange network to describe differences between ED visits resulting in 72-hour revisits to the same hospital and those resulting in revisits to a different site. METHODS: We examined data from a 31-hospital health information exchange of all ED visits during a 5-year period to identify 72-hour return visits and collected available encounter, patient, and hospital variables. Next, we used multilevel analysis of encounter-level, patient-level, and hospital-level data to describe differences between initial ED visits resulting in different-site and same-site return visits. RESULTS: We identified 12,621,159 patient visits to the 31 study EDs, including 841,259 same-site and 107,713 different-site return visits within 72 hours of initial ED presentation. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for the initial-visit characteristics' predictive relationship that any return visit would be at a different site: daytime visit (OR 1.10; 95% CI 1.07 to 1.12), patient-hospital county concordance (OR 1.40; 95% CI 1.36 to 1.44), male sex (OR 1.27; 95% CI 1.24 to 1.30), aged 65 years or older (OR 0.55; 95% CI 0.53 to 0.57), sites with an ED residency (OR 0.41; 95% CI 0.40 to 0.43), sites at an academic hospital (OR 1.12; 95% CI 1.08 to 1.15), sites with high density of surrounding EDs (OR 1.73; 95% CI 1.68 to 1.77), and sites with a high frequency of same-site return visits (OR 0.10; 95% CI 0.10 to 0.11). CONCLUSION: This analysis describes how ED encounters with early revisits to the same hospital differ from those with revisits to a second hospital. These findings challenge the use of single-site return-visit frequency as a quality measure, and, more constructively, describe how hospitals can use health information exchange to more accurately identify early ED return visits and to support programs related to these revisits.

Health Information Exchange in Emergency Medicine.

Emergency physicians often must make critical, time-sensitive decisions with a paucity of information with the realization that additional unavailable health information may exist. Health information exchange enables clinician access to patient health information from multiple sources across the spectrum of care. This can provide a more complete longitudinal record, which more accurately reflects the way most patients obtain care: across multiple providers and provider organizations. This information article explores various aspects of health information exchange that are relevant to emergency medicine and offers guidance to emergency physicians and to organized medicine for the use and promotion of this emerging technology. This article makes 5 primary emergency medicine-focused recommendations, as well as 7 additional secondary generalized recommendations, to health information exchanges, policymakers, and professional groups, which are crafted to facilitate health information exchange's purpose and demonstrate its value.

Hospital crossover increases utilization for people with epilepsy: a retrospective cohort study.

OBJECTIVES: "Hospital crossover" occurs when people visit multiple hospitals for care, which may cause gaps in electronic health records. Although crossover is common among people with epilepsy, the effect on subsequent use of health services is unknown. Understanding this effect will help prioritize health care delivery innovations targeted for this population. METHODS: We collected de-identified information from a health information exchange network describing 7,836 people with epilepsy who visited any of seven hospitals in New York, NY from 2009-2012. Data included demographics, comorbidities, and 2 years of visit information from ambulatory, inpatient, emergency department (ED), and radiology settings. We performed two complementary retrospective cohort analyses, in order to (1) illustrate the effect on a carefully selected subgroup, and (2) confirm the effect across the study population. First, we performed a matched cohort analysis on 410 pairs of individuals with and without hospital crossover in the baseline year. Second, we performed a propensity score odds weighted ordinal logistic regression analysis to estimate the effect across all 7,836 individuals. The outcomes were the use of six health services in the follow-up year. RESULTS: In the matched pair analysis, baseline hospital crossover increased the odds of more visits in the ED (odds ratio 1.42, 95% confidence interval [CI] 1.05-1.95) and radiology settings (1.7, 1.22-2.38). The regression analysis confirmed the ED and radiology findings, and also suggested that crossover led to more inpatient admissions (1.35, 1.11-1.63), head CTs (1.44, 1.04-2), and brain MRIs (2.32, 1.59-3.37). SIGNIFICANCE: Baseline hospital crossover is an independent marker for subsequent increased health service use in multiple settings among people with epilepsy. Health care delivery innovations targeted for people with epilepsy who engage in hospital crossover should prioritize (1) sharing radiology images and reports (to reduce unnecessary radiology use, particularly head CTs), and (2) improving coordination of care (to reduce unnecessary ED and inpatient use).

A conceptual framework for improved analyses of 72-hour return cases.

For more than 25 years, emergency medicine researchers have examined 72-hour return visits as a marker for high-risk patient visits and as a surrogate measure for quality of care. Individual emergency departments frequently use 72-hour returns as a screening tool to identify deficits in care, although comprehensive departmental reviews of this nature may consume considerable resources. We discuss the lack of published data supporting the use of 72-hour return frequency as an overall performance measure and examine why this is not a valid use, describe a conceptual framework for reviewing 72-hour return cases as a screening tool, and call for future studies to test various models for conducting such quality assurance reviews of patients who return to the emergency department within 72 hours.

People with epilepsy who use multiple hospitals; prevalence and associated factors assessed via a health information exchange.

OBJECTIVE: Hospital crossover occurs when people seek care at multiple hospitals, creating information gaps for physicians at the time of care. Health information exchange (HIE) is technology that fills these gaps, by allowing otherwise unaffiliated physicians to share electronic medical information. However, the potential value of HIE is understudied, particularly for chronic neurologic conditions like epilepsy. We describe the prevalence and associated factors of hospital crossover among people with epilepsy, in order to understand the epidemiology of who may benefit from HIE. METHODS: We used a cross-sectional study design to examine the bivariate and multivariable association of demographics, comorbidity, and health service utilization variables with hospital crossover, among people with epilepsy. We identified 8,074 people with epilepsy from the International Classification of Diseases, Ninth Revision (ICD-9) codes, obtained from an HIE that linked seven hospitals in Manhattan, New York. We defined hospital crossover as care from more than one hospital in any setting (inpatient, outpatient, emergency, or radiology) over 2 years. RESULTS: Of 8,074 people with epilepsy, 1,770 (22%) engaged in hospital crossover over 2 years. Crossover was associated with younger age (children compared with adults, adjusted odds ratio [OR] 1.4, 95% confidence interval [CI] 1.2-1.7), living near the hospitals (Manhattan vs. other boroughs of New York City, adjusted OR 1.6, 95% CI 1.4-1.8), more visits in the emergency, radiology, inpatient, and outpatient settings (p < 0.001 for each), and more head computerized tomography (CT) scans (p < 0.01). The diagnosis of "encephalopathy" was consistently associated with crossover in bivariate and multivariable analyses (adjusted OR 2.66, 95% CI 2.14-3.29), whereas the relationship between other comorbidities and crossover was less clear. SIGNIFICANCE: Hospital crossover is common among people with epilepsy, particularly among children, frequent users of medical services, and people living near the study hospitals. HIE should focus on these populations. Further research should investigate why hospital crossover occurs, how it affects care, and how HIE can most effectively mitigate the resultant fragmentation of medical records.

Quality and safety implications of emergency department information systems.

The Health Information Technology for Economic and Clinical Health Act of 2009 and the Centers for Medicare & Medicaid Services "meaningful use" incentive programs, in tandem with the boundless additional requirements for detailed reporting of quality metrics, have galvanized hospital efforts to implement hospital-based electronic health records. As such, emergency department information systems (EDISs) are an important and unique component of most hospitals' electronic health records. System functionality varies greatly and affects physician decisionmaking, clinician workflow, communication, and, ultimately, the overall quality of care and patient safety. This article is a joint effort by members of the Quality Improvement and Patient Safety Section and the Informatics Section of the American College of Emergency Physicians. The aim of this effort is to examine the benefits and potential threats to quality and patient safety that could result from the choice of a particular EDIS, its implementation and optimization, and the hospital's or physician group's approach to continuous improvement of the EDIS. Specifically, we explored the following areas of potential EDIS safety concerns: communication failure, wrong order-wrong patient errors, poor data display, and alert fatigue. Case studies are presented that illustrate the potential harm that could befall patients from an inferior EDIS product or suboptimal execution of such a product in the clinical environment. The authors have developed 7 recommendations to improve patient safety with respect to the deployment of EDISs. These include ensuring that emergency providers actively participate in selection of the EDIS product, in the design of processes related to EDIS implementation and optimization, and in the monitoring of the system's ongoing success or failure. Our recommendations apply to emergency departments using any type of EDIS: custom-developed systems, best-of-breed vendor systems, or enterprise systems.

[WITHDRAWN] Hexokinase-1 mitochondrial dissociation and protein O-GlcNAcylation drive heart failure with preserved ejection fraction.

The authors have requested that this preprint be removed from Research Square.

DNA damage and nuclear morphological changes in cardiac hypertrophy are mediated by SNRK through actin depolymerization.

BACKGROUND: Proper nuclear organization is critical for cardiomyocyte (CM) function, as global structural remodeling of nuclear morphology and chromatin structure underpins the development and progression of cardiovascular disease. Previous reports have implicated a role for DNA damage in cardiac hypertrophy, however, the mechanism for this process is not well delineated. AMPK family of proteins regulate metabolism and DNA damage response (DDR). Here, we examine whether a member of this family, SNF1-related kinase (SNRK), which plays a role in cardiac metabolism, is also involved in hypertrophic remodeling through changes in DDR and structural properties of the nucleus. METHODS: We subjected cardiac specific (cs)- Snrk -/- mice to trans-aortic banding (TAC) to assess the effect on cardiac function and DDR. In parallel, we modulated SNRK in vitro and assessed its effects on DDR and nuclear parameters. We also used phospho-proteomics to identify novel proteins that are phosphorylated by SNRK. Finally, co-immunoprecipitation (co-IP) was used to verify Destrin (DSTN) as the binding partner of SNRK that modulates its effects on the nucleus and DDR. RESULTS: cs- Snrk -/- mice display worse cardiac function and cardiac hypertrophy in response to TAC, and an increase in DDR marker pH2AX in their hearts. Additionally, in vitro Snrk knockdown results in increased DNA damage and chromatin compaction, along with alterations in nuclear flatness and 3D volume. Phospho-proteomic studies identified a novel SNRK target, DSTN, a member of F-actin depolymerizing factor (ADF) proteins that directly binds to and depolymerize F-actin. SNRK binds to DSTN, and DSTN downregulation reverses excess DNA damage and changes in nuclear parameters, in addition to cellular hypertrophy, with SNRK knockdown. We also demonstrate that SNRK knockdown promotes excessive actin depolymerization, measured by the increased ratio of globular (G-) actin to F-actin. Finally, Jasplakinolide, a pharmacological stabilizer of F-actin, rescues the increased DNA damage and aberrant nuclear morphology in SNRK downregulated cells. CONCLUSIONS: These results indicate that SNRK is a key player in cardiac hypertrophy and DNA damage through its interaction with DSTN. This interaction fine-tunes actin polymerization to reduce DDR and maintain proper CM nuclear shape and morphology. Clinical Perspective: What is new? Animal hearts subjected to pressure overload display increased SNF1-related kinase (SNRK) protein expression levels and cardiomyocyte specific SNRK deletion leads to aggravated myocardial hypertrophy and heart failure.We have found that downregulation of SNRK impairs DSTN-mediated actin polymerization, leading to maladaptive changes in nuclear morphology, higher DNA damage response (DDR) and increased hypertrophy. What are the clinical implications? Our results suggest that disruption of DDR through genetic loss of SNRK results in an exaggerated pressure overload-induced cardiomyocyte hypertrophy.Targeting DDR, actin polymerization or SNRK/DSTN interaction represent promising therapeutic targets in pressure overload cardiac hypertrophy.

Iron drives anabolic metabolism through active histone demethylation and mTORC1.

All eukaryotic cells require a minimal iron threshold to sustain anabolic metabolism. However, the mechanisms by which cells sense iron to regulate anabolic processes are unclear. Here we report a previously undescribed eukaryotic pathway for iron sensing in which molecular iron is required to sustain active histone demethylation and maintain the expression of critical components of the pro-anabolic mTORC1 pathway. Specifically, we identify the iron-binding histone-demethylase KDM3B as an intrinsic iron sensor that regulates mTORC1 activity by demethylating H3K9me2 at enhancers of a high-affinity leucine transporter, LAT3, and RPTOR. By directly suppressing leucine availability and RAPTOR levels, iron deficiency supersedes other nutrient inputs into mTORC1. This process occurs in vivo and is not an indirect effect by canonical iron-utilizing pathways. Because ancestral eukaryotes share homologues of KDMs and mTORC1 core components, this pathway probably pre-dated the emergence of the other kingdom-specific nutrient sensors for mTORC1.

Notifications of hospital events to outpatient clinicians using health information exchange: a post-implementation survey.

BACKGROUND: The trend towards hospitalist medicine can lead to disjointed patient care. Outpatient clinicians may be unaware of patients' encounters with a disparate healthcare system. Electronic notifications to outpatient clinicians of patients' emergency department (ED) visits and inpatient admissions and discharges using health information exchange can inform outpatient clinicians of patients' hospital-based events. OBJECTIVE: Assess outpatient clinicians' impressions of a new, secure messaging-based, patient event notification system. METHODS: Twenty outpatient clinicians receiving notifications of hospital-based events were recruited and 14 agreed to participate. Using a semi-structured interview, clinicians were asked about their use of notifications and the impact on their practices. RESULTS: Nine of 14 interviewed clinicians (64%) thought that without notifications, they would have heard about fewer than 10% of ED visits before the patient's next visit. Nine clinicians (64%) thought that without notifications, they would have heard about fewer than 25% of inpatient admissions and discharges before the patient's next visit. Six clinicians (43%) reported that they call the inpatient team more often because of notifications. Eight users (57%) thought that notifications improved patient safety by increasing their awareness of the patients' clinical events and their medication changes. Key themes identified were the importance of workflow integration and a desire for more clinical information in notifications. CONCLUSIONS: The notification system is perceived by clinicians to be of value. These findings should instigate further message-oriented use of health information exchange and point to refinements that can lead to even greater benefits.

Perceptions of health information exchange in home healthcare.

The aim of this study was to understand home healthcare nurses' current experiences in obtaining outside clinical information at the point of care and the type of clinical information they most desire in their patients' health information exchange profile. A Web-based survey was deployed to home health workers in New York to learn about their experiences retrieving outside clinical data prior to having access to health information exchange, preferred data elements and sources in their patients' health information exchange profiles, and how availability of outside clinical data may affect emergency department referrals. Of the 2383 participants, 566 responded for a 23.8% overall response rate, and 469 of these respondents were RNs. Most RNs, 96.7%, agreed that easier and quicker access to outside information would benefit delivery of care, and 72.6% said the number of emergency department referrals would decrease. When asked about pre-health information exchange access to patient data, 96.3% said it was problematic. Inpatient discharge summaries were chosen most often by the RNs as a top five desired data element 81.5% of the time. Obtaining outside clinical information has been a challenge without health information exchange, but improved access to this information may lead to improved care. Further study is required to assess experiences with the use of health information exchange.

ZFP36L2 suppresses mTORc1 through a P53-dependent pathway to prevent peripartum cardiomyopathy in mice.

Pregnancy is associated with substantial physiological changes of the heart, and disruptions in these processes can lead to peripartum cardiomyopathy (PPCM). The molecular processes that cause physiological and pathological changes in the heart during pregnancy are not well characterized. Here, we show that mTORc1 was activated in pregnancy to facilitate cardiac enlargement that was reversed after delivery in mice. mTORc1 activation in pregnancy was negatively regulated by the mRNA-destabilizing protein ZFP36L2 through its degradation of Mdm2 mRNA and P53 stabilization, leading to increased SESN2 and REDD1 expression. This pathway impeded uncontrolled cardiomyocyte hypertrophy during pregnancy, and mice with cardiac-specific Zfp36l2 deletion developed rapid cardiac dysfunction after delivery, while prenatal treatment of these mice with rapamycin improved postpartum cardiac function. Collectively, these data provide what we believe to be a novel pathway for the regulation of mTORc1 through mRNA stabilization of a P53 ubiquitin ligase. This pathway was critical for normal cardiac growth during pregnancy, and its reduction led to PPCM-like adverse remodeling in mice.

Using health information exchange to improve public health.

Public health relies on data reported by health care partners, and information technology makes such reporting easier than ever. However, data are often structured according to a variety of different terminologies and formats, making data interfaces complex and costly. As one strategy to address these challenges, health information organizations (HIOs) have been established to allow secure, integrated sharing of clinical information among numerous stakeholders, including clinical partners and public health, through health information exchange (HIE). We give detailed descriptions of 11 typical cases in which HIOs can be used for public health purposes. We believe that HIOs, and HIE in general, can improve the efficiency and quality of public health reporting, facilitate public health investigation, improve emergency response, and enable public health to communicate information to the clinical community.

Ironing out mechanisms of iron homeostasis and disorders of iron deficiency.

Iron plays an important role in mammalian physiological processes. It is a critical component for the function of many proteins, including enzymes that require heme and iron-sulfur clusters. However, excess iron is also detrimental because of its ability to catalyze the formation of reactive oxygen species. As a result, cellular and systemic iron levels are tightly regulated to prevent oxidative damage. Iron deficiency can lead to a number of pathological conditions, the most prominent being anemia. Iron deficiency should be corrected to improve adult patients' symptoms and to facilitate normal growth during fetal development and childhood. However, inappropriate use of intravenous iron in chronic conditions, such as cancer and heart failure, in the absence of clear iron deficiency can lead to unwanted side effects. Thus, this form of therapy should be reserved for certain patients who cannot tolerate oral iron and need rapid iron replenishment. Here, we will review cellular and systemic iron homeostasis and will discuss complications of iron deficiency.