A proliferative burst during preadolescence establishes the final cardiomyocyte number.

It is widely believed that perinatal cardiomyocyte terminal differentiation blocks cytokinesis, thereby causing binucleation and limiting regenerative repair after injury. This suggests that heart growth should occur entirely by cardiomyocyte hypertrophy during preadolescence when, in mice, cardiac mass increases many-fold over a few weeks. Here, we show that a thyroid hormone surge activates the IGF-1/IGF-1-R/Akt pathway on postnatal day 15 and initiates a brief but intense proliferative burst of predominantly binuclear cardiomyocytes. This proliferation increases cardiomyocyte numbers by ~40%, causing a major disparity between heart and cardiomyocyte growth. Also, the response to cardiac injury at postnatal day 15 is intermediate between that observed at postnatal days 2 and 21, further suggesting persistence of cardiomyocyte proliferative capacity beyond the perinatal period. If replicated in humans, this may allow novel regenerative therapies for heart diseases.

The test developer's dilemma: Evaluating the balance of feasibility and empiric performance of test development techniques for repeated written assessments.

PURPOSE: Written assessments face challenges when administered repeatedly, including resource-intensive item development and the potential for performance improvement secondary to item recall as opposed to understanding. This study examines the efficacy of three-item development techniques in addressing these challenges. METHODS: Learners at five training programs completed two 60-item repeated assessments. Items from the first test were randomized to one of three treatments for the second assessment: (1) Verbatim repetition, (2) Isomorphic changes, or (3) Total revisions. Primary outcomes were the stability of item psychometrics across test versions and evidence of item recall influencing performance as measured by the rate of items answered correctly and then incorrectly (correct-to-incorrect rate), which suggests guessing. RESULTS: Forty-six learners completed both tests. Item psychometrics were comparable across test versions. Correct-to-incorrect rates differed significantly between groups with the highest guessing rate (lowest recall effect) in the Total Revision group (0.15) and the lowest guessing rate (highest recall effect) in the Verbatim group (0.05), p = 0.01. CONCLUSIONS: Isomorphic and total revisions demonstrated superior performance in mitigating the effect of recall on repeated assessments. Given the high costs of total item revisions, there is promise in exploring isomorphic items as an efficient and effective approach to repeated written assessments.[Box: see text].

Sleep and asthma management in youth with poorly-controlled asthma and their caregivers: a qualitative approach.

OBJECTIVE: Youth with poorly-controlled asthma are at increased risk for sleep disturbances caused by nocturnal symptoms like coughing. Asthma-related sleep disturbances can have downstream consequences for youth with asthma and their families. This study aims to describe (1) sleep disturbances in adolescents with poorly-controlled asthma and their caregivers and (2) the relationship between sleep and asthma management. METHODS: Adolescents with poorly-controlled asthma and their caregivers completed the Family Asthma Management System Scale (FAMSS), a semi-structured interview that assesses youth asthma management within the family context. Interviews were audio-recorded and transcribed. Two authors coded each transcript for sleep-related data in NVivo using descriptive content analysis. RESULTS: Thirty-three adolescents ages 12-15 years old (M = 13.2, SD = 1.2) with poorly-controlled asthma and their caregivers participated in this study. Four main themes emerged: sleep difficulties, sleep environment, sleep and self-management, and fatigue and self-management. 42% of youth and caregivers reported worse nocturnal asthma symptoms (e.g. coughing) that caused frequent nighttime awakening. Approximately 27% of caregivers expressed distress over their child's nocturnal asthma and described their management strategies (e.g. co-sleeping, nighttime symptom monitoring). Adolescents described sleepiness as a barrier to asthma self-management tasks (e.g. medication adherence, response to exacerbation). CONCLUSION: Interview responses demonstrated the considerable interrelationship of sleep and asthma management in adolescents with poorly-controlled asthma. Asthma providers should consider discussing sleep difficulties with their adolescent patients and their families. Addressing these difficulties may help adolescents improve their asthma self-management and help caregivers better cope with their child's disease.

Pharmacists improve diabetes outcomes: a randomized controlled trial.

BACKGROUND: There is a growing shortage of primary care physicians. Pharmacists can fill the gap, and interdisciplinary teams are being evaluated as part of health care reform. OBJECTIVE: This study aimed to determine whether adding a pharmacist to an interprofessional health team will improve diabetes outcomes. METHODS: In this 2-phase pilot study, Medicaid-eligible patients with diabetes were randomized to receive standard of care (control arm) or standard of care plus the care of a pharmacist (intervention arm) for 12 months (phase 1). The primary outcome was change in glycated hemoglobin (A1C) from baseline. Secondary outcomes included identifying and correcting medication therapy problems (MTPs) for comorbid conditions, adherence to preventive care visits, health care utilization, self-rated health, and satisfaction surveys. After phase 1, patients in the control arm who did not achieve an A1C of < 8% were eligible to enroll into phase 2 where they received treatment with a pharmacist for 6 months. RESULTS: Of the 239 patients enrolled, 122 completed phase 1. At 12 months, intervention patients' mean A1C was 1.85 percentage point (pp) below baseline versus 0.94 pp for control (between-group difference 0.91 pp; P = 0.0218). Most control patients (79%) who completed phase 1 and enrolled into phase 2 improved their A1C by more than 1 pp (P < 0.01). The pharmacists completed 806 patient visits and identified 2638 MTPs. Intervention patients were more adherent to preventive care visits with nutrition (P = 0.043), ophthalmology (P = 0.002), and dentistry (P = 0.007). For intervention patients, 78% rated their experience with the pharmacist as excellent whereas, for control patients, 37% rated their experience with their provider as excellent. CONCLUSION: Pharmacist comanagement of patients with diabetes can significantly improve glucose control and patient satisfaction. Creative payment models were used to include pharmacists in the interprofessional patient care team.

Integrating Behavioral Health into Primary Care: The Role of Psychiatric Nursing in the Development of the Interprofessional Team.

BACKGROUND: Integrated behavioral health in a primary care setting is a paradigm shift that requires academic reconfiguration on how health care professionals are educated and trained in the clinical arena. METHOD: An academic university was able to create interprofessional didactic and clinical learning experiences for students within the Schools of Nursing, Social Work, Health Professions-Rehabilitation Counseling Department and Pharmacy resulting in improved models for patient care delivery. RESULTS: Interdisciplinary faculty developed the didactic, clinical and evaluative areas based on the HRSA grant work plan. Deliverables included 18 modules, case studies focused on population health, and team-focused standardized patient experiences to test their behavioral health and psychiatric skills in a primary care setting. CONCLUSIONS: Faculty from the different disciplines were able to collaborate on the deliverables, take the opportunities to engage students and collaborate on scholarly presentations at a national, state and local professional organizations. Academic course for interprofessional practice has been developed and implemented as an outcome of this grant.

Sickle Mice Are Sensitive to Hypoxia/Ischemia-Induced Stroke but Respond to Tissue-Type Plasminogen Activator Treatment.

BACKGROUND AND PURPOSE: The effects of lytic stroke therapy in patients with sickle cell anemia are unknown, although a recent study suggested that coexistent sickle cell anemia does not increase the risk of cerebral hemorrhage. This finding calls for systemic analysis of the effects of thrombolytic stroke therapy, first in humanized sickle mice, and then in patients. There is also a need for additional predictive markers of sickle cell anemia-associated vasculopathy. METHODS: We used Doppler ultrasound to examine the carotid artery of Townes sickle mice tested their responses to repetitive mild hypoxia-ischemia- and transient hypoxia-ischemia-induced stroke at 3 or 6 months of age, respectively. We also examined the effects of tPA (tissue-type plasminogen activator) treatment in transient hypoxia-ischemia-injured sickle mice. RESULTS: Three-month-old sickle cell (SS) mice showed elevated resistive index in the carotid artery and higher sensitivity to repetitive mild hypoxia-ischemia-induced cerebral infarct. Six-month-old SS mice showed greater resistive index and increased flow velocity without obstructive vasculopathy in the carotid artery. Instead, the cerebral vascular wall in SS mice showed ectopic expression of PAI-1 (plasminogen activator inhibitor-1) and P-selectin, suggesting a proadhesive and prothrombotic propensity. Indeed, SS mice showed enhanced leukocyte and platelet adherence to the cerebral vascular wall, broader fibrin deposition, and higher mortality after transient hypoxia-ischemia. Yet, post-transient hypoxia-ischemia treatment with tPA reduced thrombosis and mortality in SS mice. CONCLUSIONS: Sickle mice are sensitive to hypoxia/ischemia-induced cerebral infarct but benefit from thrombolytic treatment. An increased resistive index in carotid arteries may be an early marker of sickle cell vasculopathy.

Protein kinase C promotes cardiac fibrosis and heart failure by modulating galectin-3 expression.

Protein kinase C (PKC) and galectin-3 are two important mediators that play a key pathogenic role in cardiac hypertrophy and heart failure (HF). However, the molecular mechanisms and signaling pathways are not fully understood. In this study, we explored the relationship between and roles of PKC-α and galectin-3 in the development of HF. We found that activation of PKC by phorbol dibutyrate (PDB) increased galectin-3 expression by ~180%, as well as collagen I and fibronection accumulation in cultured HL-1 cardiomyocytes. Over-expression of galectin-3 in HL-1 cells increased collagen I protein production. Inhibition of galectin-3 by ß-lactose blocked PDB-induced galectin-3 and collagen production, indicating that galectin-3 mediates PKC-induced cardiac fibrosis. In rats subjected to pulmonary artery banding (PAB) to induce right ventricular HF, galectin-3 was increased by ~140% in the right ventricle and also by ~240% in left ventricle compared to control. The elevated galectin-3 is consistent with an increase of total and activated (phosphorylated) PKC-α, α-SMA and collagen I. Finally, we extended our findings to examine the role of angiotensin II (Ang II), which activates the PKC pathway and contributes to cardiac fibrosis and the development of HF. We found that Ang II activated the PKC-α pathway and increased galectin-3 expression and collagen production. This study provides a new insight into the molecular mechanisms of HF mediated by PKC-α and galectin-3. PKC-α promotes cardiac fibrosis and HF by stimulation of galectin-3 expression.

Topiramate-Related Hyperammonemia.

Objective: To report a case of hyperammonemia associated with the interaction between topiramate and valproic acid. Case Summary: We present a patient case with topiramate-related hyperammonemia. The patient was on topiramate prior to admission and presented with an elevated ammonia level following 2 doses of valproic acid. The increased dosing frequency of valproic acid further exacerbated the hyperammonemia. On discontinuation of topiramate and the tapering of the dose of valproic acid the patient's ammonia level returned to normal. Discussion: Valproic acid-induced hyperammonemic encephalopathy is well documented and there are several proposed mechanisms. The interaction between valproic acid and topiramate causing drug-induced hyperammonemia encephalopathy is documented in several case reports. The interaction is associated with the addition of topiramate to a patient's medication regimen that previously included valproic acid. Topiramate also has several proposed mechanisms for predisposing patients for hyperammonemia. There are limited data on topiramate monotherapy or long-term use of topiramate use causing hyperammonemia-associated encephalopathy or enhancing hyperammonemia with the addition of valproic acid. Conclusions: This case supports topiramate-related hyperammonemia and the pharmacodynamic interaction with the co-administration of valproic acid.

Survey of risk factors for osteoporosis and osteoprotective behaviors among patients with epilepsy.

The prevalence of risk factors for osteoporosis in persons with epilepsy, patients' awareness of their risk, and their engagement in osteoprotective behaviors were assessed in this study. Two hundred and sixty patients with epilepsy (F=51.5%, average age=42) completed a survey tool. Of 106 patients with a dual energy X-ray absorptiometry (DXA) result, 52% had low bone mineral density, and 11% had osteoporosis. The results suggest that the majority of patients with epilepsy do not engage in bone-protective behaviors. Those who have undergone a DXA scan may be more likely to take calcium and vitamin D supplementation compared with those who did not undergo a DXA scan, but they do not engage in other osteoprotective behaviors. Many patients did not accurately report their DXA results, indicating that better patient education is warranted.

Not another boring lecture: engaging learners with active learning techniques.

BACKGROUND: Core content in Emergency Medicine Residency Programs is traditionally covered in didactic sessions, despite evidence suggesting that learners do not retain a significant portion of what is taught during lectures. DISCUSSION: We describe techniques that medical educators can use when leading teaching sessions to foster engagement and encourage self-directed learning, based on current literature and evidence about learning. CONCLUSIONS: When these techniques are incorporated, sessions can be effective in delivering core knowledge, contextualizing content, and explaining difficult concepts, leading to increased learning.

Purification of cardiomyocytes from differentiating pluripotent stem cells using molecular beacons that target cardiomyocyte-specific mRNA.

BACKGROUND: Although methods for generating cardiomyocytes from pluripotent stem cells have been reported, current methods produce heterogeneous mixtures of cardiomyocytes and noncardiomyocyte cells. Here, we report an entirely novel system in which pluripotent stem cell-derived cardiomyocytes are purified by cardiomyocyte-specific molecular beacons (MBs). MBs are nanoscale probes that emit a fluorescence signal when hybridized to target mRNAs. METHOD AND RESULTS: Five MBs targeting mRNAs of either cardiac troponin T or myosin heavy chain 6/7 were generated. Among 5 MBs, an MB that targeted myosin heavy chain 6/7 mRNA (MHC1-MB) identified up to 99% of HL-1 cardiomyocytes, a mouse cardiomyocyte cell line, but <3% of 4 noncardiomyocyte cell types in flow cytometry analysis, which indicates that MHC1-MB is specific for identifying cardiomyocytes. We delivered MHC1-MB into cardiomyogenically differentiated pluripotent stem cells through nucleofection. The detection rate of cardiomyocytes was similar to the percentages of cardiac troponin T- or cardiac troponin I-positive cardiomyocytes, which supports the specificity of MBs. Finally, MHC1-MB-positive cells were sorted by fluorescence-activated cell sorter from mouse and human pluripotent stem cell differentiating cultures, and ≈97% cells expressed cardiac troponin T or cardiac troponin I as determined by flow cytometry. These MB-based sorted cells maintained their cardiomyocyte characteristics, which was verified by spontaneous beating, electrophysiological studies, and expression of cardiac proteins. When transplanted in a myocardial infarction model, MB-based purified cardiomyocytes improved cardiac function and demonstrated significant engraftment for 4 weeks without forming tumors. CONCLUSIONS: We developed a novel cardiomyocyte selection system that allows production of highly purified cardiomyocytes. These purified cardiomyocytes and this system can be valuable for cell therapy and drug discovery.

Special Education Services Received by Students with Autism Spectrum Disorders from Preschool through High School.

Little is known about how special education services received by students with Autism Spectrum Disorders (ASDs) differ by age, disability severity, and demographic characteristics. Using three national datasets, the Pre-Elementary Education Longitudinal Study (PEELS), the Special Education Elementary Longitudinal Study (SEELS), and the National Longitudinal Transition Study-2 (NLTS2), this study examined the age trends in special education services received by students with ASDs from preschool through high school. Elementary-school students with ASDs had higher odds of receiving adaptive physical education, specialized computer software or hardware, and special transportation, but lower odds of receiving learning strategies/study skills support than their preschool peers. Secondary-school students had lower odds of receiving speech/language or occupational therapy and of having a behavior management program, but higher odds of receiving mental health or social work services than their elementary-school peers. Both disability severity and demographic characteristics were associated with differences in special education service receipt rates.

Mitochondrial calcium and reactive oxygen species regulate agonist-initiated platelet phosphatidylserine exposure.

OBJECTIVE: To study the interactions of cytoplasmic calcium elevation, mitochondrial permeability transition pore (mPTP) formation, and reactive oxygen species formation in the regulation of phosphatidylserine (PS) exposure in platelets. METHODS AND RESULTS: mPTP formation, but not the degree of cytoplasmic calcium elevation, was associated with PS exposure in wild-type, cyclophilin D-null, ionomycin-treated, and reactive oxygen species-treated platelets. In the absence of the mPTP regulator cyclophilin D, agonist-initiated mPTP formation and high-level PS exposure were markedly blunted, but cytoplasmic calcium transients were unchanged. Mitochondrial calcium (Ca(2+)(mit)) transients and reactive oxygen species, key regulators of mPTP formation, were examined in strongly stimulated platelets. Increased reactive oxygen species production occurred in strongly stimulated platelets and was dependent on extracellular calcium entry, but not the presence of cyclophilin D. Ca(2+)(mit) increased significantly in strongly stimulated platelets. Abrogation of Ca(2+)(mit) entry, either by inhibition of the Ca(2+)(mit) uniporter or mitochondrial depolarization, prevented mPTP formation and exposure but not platelet aggregation or granule release. CONCLUSIONS: Sustained cytoplasmic calcium levels are necessary, but not sufficient, for high-level PS exposure in response to agonists. Increased Ca(2+)(mit) levels are a key signal initiating mPTP formation and PS exposure. Blockade of Ca(2+)(mit) entry allows the specific inhibition of platelet procoagulant activity.

Teriflunomide for the treatment of relapsing multiple sclerosis: a review of clinical data.

OBJECTIVE: To review the pharmacology and clinical data for teriflunomide in relapsing multiple sclerosis (MS). DATA SOURCES: A literature search from 1966 to May 2013 using PubMed/MEDLINE, Web of Science, International Pharmaceutical Abstracts, Academic Search Premiere, Science Citation Index, and the national clinical trials registry was performed using the terms teriflunomide, HMR1726, and A771726. All articles containing human clinical trial data and relevant pharmacologic information were reviewed. STUDY SELECTION/DATA EXTRACTION: Phase 2 and phase 3 clinical trials for teriflunomide were evaluated. All peer-reviewed articles with clinically relevant information were reviewed. Priority for inclusion was placed on randomized controlled trials. DATA SYNTHESIS: Three phase 2 and three phase 3 clinical trials have evaluated teriflunomide as monotherapy or as adjunctive therapy in approximately 3000 patients with relapsing forms of MS. The phase 3 studies used annualized relapse rate, magnetic resonance imaging changes, and Expanded Disability Status Scale scores as outcome measures. One additional Phase 3 clinical study is ongoing. The annualized relapse rates and magnetic resonance imaging findings were improved compared to those with placebo and similar to or improved compared with those with subcutaneously administered interferon-ß-1a 44 µg thrice weekly. Durability of response is supported by open-label extension studies. Common adverse events include increased liver function enzymes, alopecia, diarrhea, influenza, nausea, and paresthesias. Treatment discontinuation was not common and occurred in approximately 10% of patients in phase 3 studies. CONCLUSIONS: Teriflunomide is an effective and safe oral treatment option for relapsing MS. It can be used as monotherapy or added to an interferon or glatiramer acetate. It reduces the rate of relapse and may slow disease progression. The advantages of this drug are the convenience of oral administration and good tolerability. The disadvantage is the lack of long-term safety data and data about the benefit of combination therapy.

Educator's blueprint: A how-to guide for developing high-quality multiple-choice questions.

Multiple-choice questions are commonly used for assessing learners' knowledge, as part of educational programs and scholarly endeavors. To ensure that questions accurately assess the learners and provide meaningful data, it is important to understand best practices in multiple-choice question design. This Educator's Blueprint paper provides 10 strategies for developing high-quality multiple-choice questions. These strategies include determining the purpose, objectives, and scope of the question; assembling a writing team; writing succinctly; asking questions that assess knowledge and comprehension rather than test-taking ability; ensuring consistent and independent answer choices; using plausible foils; avoiding grouped options; selecting the ideal response number and order; writing high-quality explanations; and gathering validity evidence before and evaluating the questions after use.

Post hoc depression analysis from a pharmacist-led diabetes trial.

Introduction: Diabetes and depression may present concurrently, and clinical pharmacists are well equipped to manage these conditions. Clinical pharmacists were grant funded to implement a diabetes-focused randomized controlled trial in a Federally Qualified Health Center. The objective of this analysis is to evaluate if glycemic control and depressive symptoms improve for patients with diabetes and depression with additional management from clinical pharmacists compared with those receiving the standard of care. Methods: This is a post hoc subgroup analysis of a diabetes-focused randomized controlled trial. Pharmacists enrolled patients with type 2 diabetes mellitus (T2DM) and a glycated hemoglobin (A1C) greater than 8% and randomly assigned them to 1 of 2 cohorts, one managed by the primary care provider alone and one with additional care from the pharmacist. Pharmacists completed encounters with patients who have T2DM with or without depression to comprehensively optimize pharmacotherapy while tracking glycemic and depressive outcomes throughout the study. Results: A1C improved from baseline to 6 months in patients with depressive symptoms who received additional care from pharmacists by -2.4 percentage points (SD, 2.41) compared with a -0.1 percentage point (SD, 1.78) reduction in the control arm (P .0081), and there was no change in depressive symptoms. Discussion: Patients with T2DM and depressive symptoms experienced better diabetes outcomes with additional pharmacist management compared with a similar cohort of patients with depressive symptoms, managed independently by primary care providers. These patients with diabetes and comorbid depression received a higher level of engagement and care from the pharmacists, which led to more therapeutic interventions.

Resident Physician Interactions and Engagement With Written Assessments of Performance.

BACKGROUND AND OBJECTIVES: Despite the requirements of the Accreditation Council for Graduate Medical Education (ACGME) to provide feedback, assessments are often not meeting the needs of resident learners. The objective of this study was to explore residents' approach to reviewing, interpreting, and incorporating the feedback provided in written faculty assessments. METHODS: We conducted semistructured interviews with 14 family medicine residents. We used line-by-line iterative coding of the transcripts through the constant comparative method to identify themes and reach a consensus. RESULTS: The study revealed the following themes: (1) residents value the narrative portion of assessments over numerical ratings, (2) performance reflection and reaction are part of the feedback process, (3) residents had difficulty incorporating formal assessments as many did not provide actionable feedback. CONCLUSIONS: Residents reported that narrative feedback gives more insight to performance and leads to actionable changes in behaviors. Programs should consider education for both faculty and residents on the usefulness, importance, and purpose of the ACGME Milestones in order to accurately determine resident competency and provide a summative assessment. Until the purpose of the ACGME Milestones is realized and utilized, it should be noted that the comment portion of evaluations will likely be the focus of the resident's interaction with their assessments.

Polysomnography findings in children with spinal muscular atrophy after onasemnogene-abeparvovec.

BACKGROUND: Sleep disordered breathing (SDB) is common in patients with neuromuscular diseases, including spinal muscular atrophy (SMA). While polysomnography (PSG) findings have been described in natural history studies of patients with SMA, reports regarding PSG in treated children are limited to nusinersen. We aim to describe the sleep characteristics in a cohort of children treated with Onasemnogene-abeparvovec. METHODS: We conducted a cross-sectional cohort study of children with SMA followed at the University of Florida Center for neuromuscular and rare diseases and had a diagnostic or split night PSG after SMA treatment. RESULTS: Eight children were included in the cohort (four female), aged 5-250 days at diagnosis. Five children had two survival motor neuron 2 (SMN2) copies, two had three SMN2 copies and one subject had four SMN2 copies. Median age at the time of treatment was 46.5 days (range 20-257). All children received onasemnogene-abeparvovec (OA) before their PSG; in addition to OA, one received nusinersen and one received risdiplam. Apnea hypopnea index (AHI) ranged from 3.6 to 24.1/h. REM AHI was higher than NREM AHI. Median Children's Hospital of Philadelphia Infant test of neuromuscular disorders (CHOP-Intend) score at the time of PSG was 55 (range 33-64). There was no correlation between age at treatment, CHOP-Intend score and AHI. CONCLUSION: SDB is common in treated children with SMA, regardless of age at diagnosis, treatment and neuromotor scores. While AHI may not be the only indicator of SDB in this population, indications, timing of PSG in this cohort remain unknown.

Insulin ameliorates miR-1-induced injury in H9c2 cells under oxidative stress via Akt activation.

Growing evidence indicates that aberrant upregulation of microRNA-1 (miR-1) occurs in ischemic myocardium. In addition, insulin elicits metabolism-independent cardioprotection against cardiovascular diseases. The aim of this study is to determine whether insulin ameliorates miR-1-induced injury in H9c2 cells under oxidative stress and to investigate the underlying mechanisms. By quantitative real-time RT-PCR (qRT-PCR), we show that miR-1 is upregulated in H9c2 cells after treatment with hydrogen peroxide (H(2)O(2)), and this effect is both dose- and time dependent. Furthermore, expression of miR-1 decreased significantly after insulin treatment (4.5 ± 0.1 vs. 3.0 ± 0.2, p < 0.05). To determine the potential role of miR-1 in cellular injury and gene regulation, adenovirus-mediated overexpression of miR-1 was used. Overexpression of miR-1 decreased cell viability by 28 ± 2 % (n = 6, p < 0.05) and damaged Akt activation with or without H(2)O(2) treatment. To further investigate the effect of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in miR-1-induced injury, H9c2 cells were pretreated with LY294002 (10 µM LY, a specific inhibitor of PI3K) with or without insulin (100 nM) and subjected to H(2)O(2) treatment. LY pretreatment-inhibited Akt activation, lead to increased reactive oxygen species (ROS), and further decreased cell viability induced by miR-1 (n = 6, p < 0.05, n = 9-10 cells/group, p < 0.05 and n = 6, p < 0.05) under oxidative stress. This effect was abolished by insulin. In summary, our findings suggest that miR-1 expression is sensitive to H(2)O(2) stimulation. In addition, insulin decreases miR-1 expression and induces a marked protective effect on miR-1-induced injury under oxidative stress, which may be mediated by the Akt-mediated pathway. These results provide an important, novel clue as to the mechanism of the cardiovascular action of insulin.

Age- and chamber-specific differences in oxidative stress after ischemic injury.

Each year, tens of thousands of children undergo cardiopulmonary bypass (CPB) to correct congenital heart defects. Although necessary for surgery, CPB involves stopping the heart and exposing it to ischemic conditions. On reoxygenation, the heart can experience effects similar to that of acute myocardial infarction. Although much is known about adult injury, little is known about the effects of global ischemia on newborn ventricles. We studied newborn (2 to 4 days old) and adult (>8 weeks old) rabbit hearts subjected to ischemia-reperfusion (30 min of ischemia and 60 min of reperfusion). Our data demonstrated chamber- and age-specific changes in oxidative stress. During ischemia, hydrogen peroxide (H(2)O(2)) increased in both right-ventricular (RV) and left-ventricular (LV) myocytes of the newborn, although only the RV change was significant. In contrast, there was no significant increase in H(2)O(2) in either RV or LV myocytes of adults. There was a fivefold increase in H(2)O(2) formation in newborn RV myocytes compared with adults (P = 0.006). In whole-heart tissue, superoxide dismutase activity increased from sham versus ischemia in the left ventricle of both adult and newborn hearts, but it was increased only in the right ventricle of the newborn heart. Catalase activity was significantly increased after ischemia in both adult ventricles, whereas no increase was seen in newborn compared with sham hearts. In addition, catalase levels in newborns were significantly lower, indicating less scavenging potential. Nanoparticle-encapsulated ebselen, given as an intracardiac injection into the right or left ventricle of newborn hearts, significantly increased functional recovery of developed pressure only in the right ventricle, indicating the potential for localized antioxidant therapy during and after pediatric surgical procedures.