Exploring US internal medicine resident career preferences: a Q-methodology study.

Career selection in medicine is a complex and underexplored process. Most medical career studies performed in the U.S. focused on the effect of demographic variables and medical education debt on career choice. Considering ongoing U.S. physician workforce shortages and the trilateral adaptive model of career decision making, a robust assessment of professional attitudes and work-life preferences is necessary. The objective of this study was to explore and define the dominant viewpoints related to career choice selection in a cohort of U.S. IM residents. We administered an electronic Q-sort in which 218 IM residents sorted 50 statements reflecting the spectrum of opinions that influence postgraduate career choice decisions. Participants provided comments that explained the reasoning behind their individual responses. In the final year of residency training, we ascertained participating residents' chosen career. Factor analysis grouped similar sorts and revealed four distinct viewpoints. We characterized the viewpoints as "Fellowship-Bound-Academic," "Altruistic-Longitudinal-Generalist," "Inpatient-Burnout-Aware," and "Lifestyle-Focused-Consultant." There is concordance between residents who loaded significantly onto a viewpoint and their ultimate career choice. Four dominant career choice viewpoints were found among contemporary U.S. IM residents. These viewpoints reflect the intersection of competing priorities, personal interests, professional identity, socio-economic factors, and work/life satisfaction. Better appreciation of determinants of IM residents' career choices may help address workforce shortages and enhance professional satisfaction.

Peer observation to develop resident teaching.

BACKGROUND: Developing teaching skills is a fundamental part of physician postgraduate training. Although resident-as-teacher curricula are proliferating, there is no clear consensus on how best to train resident physicians as clinical teachers. Peer observation has been shown to be effective in other settings, including faculty development, and could be adopted for resident teaching skill development. METHODS: The authors developed a 5-day resident-as-teacher training programme, founded on three principles: (i) focused seminars; (ii) authentic teaching experiences; and (iii) peer observation. To provide genuine teaching experiences, course participants taught regularly scheduled curricular sessions. Residents were partnered with a peer; each delivered two teaching sessions and provided two peer observations. RESULTS: Evaluations revealed the course had a 'major impact' on participants' teaching. Significant improvements were observed in self-reported comfort and confidence with teaching and in providing feedback. Peer observation was cited as the most effective component of the course. Nearly all residents were both comfortable receiving and providing peer-observed feedback. A majority of residents reported that they were more likely to seek feedback as a result of the course. The faculty member time required was limited to 1-2 hours per individual. DISCUSSION: Peer observation can be used effectively to engage residents and advance clinical teaching skills. Residents were generally comfortable giving and receiving feedback in peer-observer dyads. Employing peer observation also reduced the amount of faculty member time needed to deliver resident-as-teacher programming, thereby facilitating the scalability of the programme. Allowing participants to teach during regular conference time allowed for smooth integration into the pre-existing schedule for the training programme.

Objective Evidence of Reflux Control After Magnetic Sphincter Augmentation: One Year Results From a Post Approval Study.

OBJECTIVE: To report 1-year results from a 5-year mandated study. SUMMARY BACKGROUND DATA: In 2012, the United States Food and Drug Administration approved magnetic sphincter augmentation (MSA) with the LINX Reflux Management System (Torax Medical, Shoreview, MN), a novel device for the surgical treatment of gastroesophageal reflux disease (GERD). Continued assessment of safety and effectiveness has been monitored in a Post Approval Study. METHODS: Multicenter, prospective study of patients with pathologic acid reflux confirmed by esophageal pH testing undergoing MSA. Predefined clinical outcomes were assessed at the annual visit including a validated, disease-specific questionnaire, esophagogastricduodenoscopy and esophageal pH monitoring, and use of proton pump inhibitors. RESULTS: A total of 200 patients (102 males, 98 females) with a mean age of 48.5 years (range 19.7-71.6) were treated with MSA between March 2013 and August 2015. At 1 year, the mean total acid exposure time decreased from 10.0% at baseline to 3.6%, and 74.4% of patients had normal esophageal acid exposure time (% time pH<4 ≤5.3%). GERD Health-Related Quality of Life scores improved from a median score of 26.0 at baseline to 4.0 at 1 year, with 84% of patients meeting the predefined success criteria of at least a 50% reduction in total GERD Health-Related Quality of Life score compared with baseline. The device removal rate at 1 year was 2.5%. One erosion and no serious adverse events were reported. CONCLUSIONS: Safety and effectiveness of magnetic sphincter augmentation has been demonstrated outside of an investigational setting to further confirm MSA as treatment for GERD.

Evaluating Nonoperative Treatments for Adhesive Capsulitis.

Patients commonly present with shoulder complaints to the primary care and orthopaedic setting. The differential includes rotator cuff tears, subacromial impingement, osteoarthritis, and adhesive capsulitis, also known as frozen shoulder. Despite the prevalence of adhesive capsulitis, it is commonly misdiagnosed and management remains unclear. This article reviews the presentation of adhesive capsulitis, presents an overview of the pathophysiology of this poorly understood disease, and evaluates nonoperative treatment options for adhesive capsulitis. (Journal of Surgical Orthopaedic Advances 26(4):193-199, 2017).

Long-term Outcomes of Patients Receiving a Magnetic Sphincter Augmentation Device for Gastroesophageal Reflux.

BACKGROUND & AIMS: Based on results from year 2 of a 5-year trial, in 2012 the US Food and Drug Administration approved the use of a magnetic device to augment lower esophageal sphincter function in patients with gastroesophageal reflux disease (GERD). We report the final results of 5 years of follow-up evaluation of patients who received this device. METHODS: We performed a prospective study of the safety and efficacy of a magnetic device in 100 adults with GERD for 6 months or more, who were partially responsive to daily proton pump inhibitors (PPIs) and had evidence of pathologic esophageal acid exposure, at 14 centers in the United States and The Netherlands. The magnetic device was placed using standard laparoscopic tools and techniques. Eighty-five subjects were followed up for 5 years to evaluate quality of life, reflux control, use of PPIs, and side effects. The GERD-health-related quality of life (GERD-HRQL) questionnaire was administered at baseline to patients on and off PPIs, and after placement of the device; patients served as their own controls. A partial response to PPIs was defined as a GERD-HRQL score of 10 or less on PPIs and a score of 15 or higher off PPIs, or a 6-point or more improvement when scores on vs off PPI were compared. RESULTS: Over the follow-up period, no device erosions, migrations, or malfunctions occurred. At baseline, the median GERD-HRQL scores were 27 in patients not taking PPIs and 11 in patients on PPIs; 5 years after device placement this score decreased to 4. All patients used PPIs at baseline; this value decreased to 15.3% at 5 years. Moderate or severe regurgitation occurred in 57% of subjects at baseline, but only 1.2% at 5 years. All patients reported the ability to belch and vomit if needed. Bothersome dysphagia was present in 5% at baseline and in 6% at 5 years. Bothersome gas-bloat was present in 52% at baseline and decreased to 8.3% at 5 years. CONCLUSIONS: Augmentation of the lower esophageal sphincter with a magnetic device provides significant and sustained control of reflux, with minimal side effects or complications. No new safety risks emerged over a 5-year follow-up period. These findings validate the long-term safety and efficacy of the magnetic sphincter augmentation device for patients with GERD. ClinicalTrials.gov no: NCT00776997.

Improving the performance of high-laser-damage-threshold, multilayer dielectric pulse-compression gratings through low-temperature chemical cleaning.

A low-temperature chemical cleaning approach has been developed to improve the performance of multilayer dielectric pulse-compressor gratings for use in the OMEGA EP laser system. X-ray photoelectron spectroscopy results guided the selection of targeted cleaning steps to strip specific families of manufacturing residues without damaging the grating's fragile 3D profile. Grating coupons that were cleaned using the optimized method consistently met OMEGA EP requirements on diffraction efficiency and 1054 nm laser-damage resistance at 10 ps. The disappearance of laser-conditioning effects for the highest-damage-threshold samples suggests a transition from a contamination-driven laser-damage mechanism to defect-driven damage for well-cleaned components.

Esophageal sphincter device for gastroesophageal reflux disease.

BACKGROUND: Patients with gastroesophageal reflux disease who have a partial response to proton-pump inhibitors often seek alternative therapy. We evaluated the safety and effectiveness of a new magnetic device to augment the lower esophageal sphincter. METHODS: We prospectively assessed 100 patients with gastroesophageal reflux disease before and after sphincter augmentation. The study did not include a concurrent control group. The primary outcome measure was normalization of esophageal acid exposure or a 50% or greater reduction in exposure at 1 year. Secondary outcomes were 50% or greater improvement in quality of life related to gastroesophageal reflux disease and a 50% or greater reduction in the use of proton-pump inhibitors at 1 year. For each outcome, the prespecified definition of successful treatment was achievement of the outcome in at least 60% of the patients. The 3-year results of a 5-year study are reported. RESULTS: The primary outcome was achieved in 64% of patients (95% confidence interval [CI], 54 to 73). For the secondary outcomes, a reduction of 50% or more in the use of proton-pump inhibitors occurred in 93% of patients, and there was improvement of 50% or more in quality-of-life scores in 92%, as compared with scores for patients assessed at baseline while they were not taking proton-pump inhibitors. The most frequent adverse event was dysphagia (in 68% of patients postoperatively, in 11% at 1 year, and in 4% at 3 years). Serious adverse events occurred in six patients, and in six patients the device was removed. CONCLUSIONS: In this single-group evaluation of 100 patients before and after sphincter augmentation with a magnetic device, exposure to esophageal acid decreased, reflux symptoms improved, and use of proton-pump inhibitors decreased. Follow-up studies are needed to assess long-term safety. (Funded by Torax Medical; ClinicalTrials.gov number, NCT00776997.).

Necroptosis, necrostatins and tissue injury.

Cell death is an integral part of the life of an organism being necessary for the maintenance of organs and tissues. If, however, cell death is allowed to proceed unrestricted, tissue damage and degenerative disease may ensue. Until recently, three morphologically distinct types of cell death were recognized, apoptosis (type I), autophagy (type II) and necrosis (type III). Apoptosis is a highly regulated, genetically determined mechanism designed to dismantle cells systematically (e.g. cells that are no longer functionally viable), via protease (caspase) action, and maintain homeostasis. Autophagy is responsible for the degradation of cytoplasmic material, e.g. proteins and organelles, through autophagosome formation and subsequent proteolytic degradation by lysosomes, and is normally considered in the context of survival although it is sometimes associated with cell death. Necrosis was formerly considered to be an accidental, unregulated form of cell death resulting from excessive stress, although it has been suggested that this is an over-simplistic view as necrosis may under certain circumstances involve the mobilization of specific transduction mechanisms. Indeed, recently, an alternative death pathway, termed necroptosis, was delineated and proposed as a form of 'programmed necrosis'. Identified with the aid of specific inhibitors called necrostatins, necroptosis shares characteristics with both necrosis and apoptosis. Necroptosis involves Fas/tumour necrosis factor-α death domain receptor activation and inhibition of receptor-interacting protein I kinase, and it has been suggested that it may contribute to the development of neurological and myocardial diseases. Significantly, necrostatin-like drugs have been mooted as possible future therapeutic agents for the treatment of degenerative conditions.

Adipocytokines, cardiovascular pathophysiology and myocardial protection.

Reducing myocardial damage resulting from ischaemia-reperfusion (I/R) is vital in ensuring patient recovery and survival. It relies upon the activation of the so-called Reperfusion Injury Salvage Kinase (RISK) pathway. Experimentally various treatments, both mechanical and chemical, have been shown to protect the myocardium against I/R injury. Chemical facilitators of myocardial preservation include endogenous factors such as insulin, erythropoietin and glucagon-like peptide 1. The adipocytokines, products of white adipose tissue, are important peptide hormones with respect to metabolic control and satiety, and were formerly considered in the context of obesity and metabolic disease. More recently, however, evidence has been presented indicating that the adipocytokines play significant roles in cardiac function and, as we have suggested, in myocardial protection. To date leptin, adiponectin, apelin and visfatin have all been shown to protect against I/R injury. Significantly, the protection afforded by these peptides involves the activation of kinases which are key elements of the mechanisms underlying tissue preservation, including the RISK pathway components PI3K-Akt and p44/42, and inhibition of the mitochondrial permeability transition pore (MPTP). In this article we examine the roles played by the adipocytokines in cardiovascular function and disease. In particular, we focus on the evidence that these peptides promote myocardial survival, much of it having been obtained in this laboratory. To conclude, we discuss some future directions in the field, including the prospects for some of the adipocytokines finding application as therapeutic agents in myocardial infarction.

Failure of the adipocytokine, resistin, to protect the heart from ischemia-reperfusion injury.

Experimental studies have linked the adipocytokines with acute cardioprotection. Whether the adipocytokine, resistin, confers protection is, however, debatable. In the current study, the actions of resistin, administered at reperfusion, were investigated in in vivo and in vitro rodent and in vitro human models of myocardial ischemia-reperfusion (I/R) injury. Resistin did not reduce infarct size in Langendorff-perfused rat hearts or murine hearts perfused in vivo. Resistin also did not protect human atrial muscle subjected to hypoxia-reoxygenation. Although cyclosporin A delayed mitochondrial permeability transition pore (MPTP) opening in murine cardiomyocytes, resistin was ineffective. Western blot analysis revealed that resistin treatment was associated with enhanced phosphorylation of Akt, at both the serine-473 (+ 51.9%, P = .01) and threonine-308 (+107%, P < .01) phosphorylation sites, although not to the extent seen with ischemic preconditioning (+132.5%, P = .002 and +389.1%, P < .01, respectively). We conclude that resistin administered at reperfusion at concentrations/doses equivalent to normal (upper end) and pathological serum levels does not protect against I/R injury or inhibit MPTP opening.

Leptin-induced cardioprotection involves JAK/STAT signaling that may be linked to the mitochondrial permeability transition pore.

Leptin-induced protection against myocardial ischemia-reperfusion (I/R) injury involves the activation of the reperfusion injury salvage kinase pathway, incorporating phosphatidylinositol 3-kinase-Akt/protein kinase B and p44/42 MAPK, and the inhibition of the mitochondrial permeability transition pore (MPTP). Recently published data indicate that the JAK/STAT signaling pathway, which mediates the metabolic actions of leptin, also plays a pivotal role in cardioprotection. Consequently, in the present study we considered the possibility that JAK/STAT signaling linked to the MPTP may be involved in modulating the cardioprotective actions of leptin. Employing rat in vitro models (Langendorff-perfused hearts and cardiomyocytes) of I/R injury, we investigated the actions of leptin (10 nM), administered at reperfusion, in the presence or absence of the JAK2 inhibitor, AG-490 (5 µM). Leptin reduced infarct size significantly (control, 60.05 ± 7.41% vs. leptin treated, 29.9 ± 3.24%, P < 0.05), protection being abolished by AG-490. Time course studies revealed that leptin caused a 171% (P < 0.001) increase in STAT3/tyrosine-705 phosphorylation at 2.5 min reperfusion; however, increases were not seen at 5, 10, 15, or 30 min reperfusion. Contrasting with STAT3, Akt/serine-473 phosphorylation was not significantly increased until 15 min into the reperfusion phase (140%, P < 0.05). AG-490 blocked the leptin-induced rise in STAT3 phosphorylation seen at 2.5 min reperfusion but did not influence Akt/serine-473 phosphorylation at 15 min. Leptin reduced the MPTP opening (P < 0.001), which was blocked by AG-490. This is the first study to yield evidence that JAK/STAT signaling linked to the MPTP plays a role in leptin-induced cardioprotection. Under the experimental conditions employed, STAT3 phosphorylation appears to have occurred earlier during reperfusion than that of Akt. Further research into the interactions between these two signaling pathways in the setting of I/R injury is, however, required.

The cannabinoid CB1 receptor antagonist, rimonabant, protects against acute myocardial infarction.

CB1 antagonism is associated with reduced doxorubicin-induced cardiotoxicity and decreased cerebrocortical infarction. Rimonabant, a selective CB1 receptor antagonist, was, before it was withdrawn, proposed as a treatment for obesity and reported to reduce cardiovascular risk by improving glucose and lipid profiles and raising adiponectin levels. The cardioprotective actions of rimonabant in 6-week-old C57BL/6J mice fed either high-fat (HFD) or standard diets (STD) for 8 weeks were investigated. At 14 weeks, mice received rimonabant (10 mg/kg/day, i.p.) or vehicle for 1 week and were then subjected to an in vivo acute myocardial infarction. The influence of rimonabant on infarct size (IS) in CB1 knockout (CB1-/-) and wild-type (CB1+/+) mice was also examined. C57BL/6J mice that had been maintained on STD or HFD exhibited 4.3 and 21.4% reductions in body weight following 7 days rimonabant treatment. Rimonabant reduced IS in both STD (29.6 +/- 3.5% vs. 49.8 +/- 6.9% in control, P < 0.05) and HFD (26.9 +/- 1.5% vs. 48.7 +/- 7% in control, P < 0.05) mice. In CB1-/- mice rimonabant failed to reduce body weight or IS (51.0 +/- 5.3% vs. 49.7 +/- 4.7% in control, P > 0.05), although significant reductions were seen in CB1+/+ mice (IS, 48.9 +/- 4.6% control vs. 30.5 +/- 3.1% rimonabant, P < 0.05). To exclude the possibility that weight loss alone induced cardioprotection, HFD mice were switched to STD for 7 days (HFD-STD), resulting in an 11.3 +/- 1.0% decrease in body weight compared to control (+2.1 +/- 1.1% in HFD). This, however, was not associated with IS reduction (39.1 +/- 3.9% HFD-STD vs. 40.0 +/- 5.3% HFD, P > 0.05). Serum and cardiac adiponectin levels were unaltered by rimonabant treatment. HL-1 cell death was not prevented by 1 or 7 days treatment with rimonabant. We conclude that rimonabant-induced infarct limitation may involve the CB1 receptor, although not necessarily cardiac CB1 receptors, and is unrelated to weight loss or altered adiponectin synthesis.

The cardioprotective actions of leptin are lost in the Zucker obese (fa/fa) rat.

Protection against myocardial ischemia-reperfusion injury, including that induced by leptin, involves activation of the reperfusion injury salvage kinase pathway and inhibition of the mitochondrial permeability transition pore. In the current study, we explored the mechanisms underlying leptin-induced cardioprotection further with reference to the leptin receptor (OB-R) and obesity. We examined hearts from Wistar and Zucker lean rats that express functional OB-R and Zucker obese (fa/fa) rats with nonfunctional OB-R. In Langendorff experiments, leptin (10 nM) caused significant reductions in infarct size in hearts from Wistar (leptin treated, 32.4% +/- 3.9% vs. control, 53.2% +/- 3.2%, P < 0.01) and Zucker lean animals (leptin treated, 25.2% +/- 3.7% vs. control, 53.9% +/- 11.3%, P < 0.01). By contrast, hearts from (fa/fa) did not exhibit significant decreases in infarct size. Leptin increased p44 and p42 phosphorylation in Wistar rat hearts by 103.9% (P < 0.05) and 157.3% (P < 0.001), respectively, and by 97.0% (P < 0.05) and 158.1% (P < 0.05) in hearts from Zucker lean rats. Akt/serine-473 phosphorylation was increased in Wistar hearts by 96.7% (P < 0.05), whereas Akt/threonine-308 phosphorylation was elevated by 43.9% (P < 0.05) in Zucker lean rat hearts. Leptin did not influence Akt or p44/42 phosphorylation in (fa/fa) animals. On leptin treatment, mitochondrial permeability transition pore opening was delayed by 43% (P < 0.01) and 30.9% (P < 0.01), respectively, in cardiomyocytes from Wistar and Zucker lean rat hearts but not in cardiomyocytes from (fa/fa). This study provides the first evidence that myocardial sensitivity to the tissue preserving actions of leptin is influenced by adiposity and OB-R status.

Platelet alpha- and beta-secretase activities: A preliminary study in normal human subjects.

beta-amyloid (Abeta) arises from an amyloid precursor protein (APP) via beta- and gamma-secretase proteolysis. Platelets are the primary depot of APP in the circulation and may be a source of cerebral Abeta. We measured the platelet activities of alpha- and beta-secretases in normal individuals. Platelet alpha- and beta-secretase activities were linear with respect to incubation time and quantity of platelet extract included in the assays. beta-secretase activity, calculated relative to platelet count (PC) and platelet protein (PP), varied between individuals 3.5-fold and 4.6-fold, respectively. Meanwhile, alpha-secretase varied 3.75-fold and 5.8-fold. beta-secretase/alpha-secretase ratios varied 4.1-fold (PC) or 10.5-fold (PP). beta-secretase correlated with age (r = 0.779, p < 0.02, PP) and mean platelet volume (MPV) (r = 0.702, p < 0.05, PC). alpha-secretase correlated negatively with high-density lipoprotein (HDL) (-0.76, p < 0.01, PP). beta-secretase/alpha-secretase ratios correlated with MPV (r = 0.67, p < 0.05, PC) and HDL (r = 0.77, p < 0.02, PP). These data could indicate that platelet secretase activity is related to aging, platelet size and plasma lipoprotein levels. Clearly, however, this is a preliminary study involving a limited number of individuals and further, more detailed, investigations are required to establish that such relationships are valid.

The novel adipocytokine visfatin exerts direct cardioprotective effects.

Visfatin is an adipocytokine capable of mimicking the glucose-lowering effects of insulin and activating the pro-survival kinases phosphatidylinositol-3-OH kinase (PI3K)-protein kinase B (Akt) and mitogen-activated protein kinase kinase 1 and 2 (MEK1/2)-extracellular signal-regulated kinase 1 and 2 (Erk 1/2). Experimental studies have demonstrated that the activation of these kinases confers cardioprotection through the inhibition of the mitochondrial permeability transition pore (mPTP). Whether visfatin is capable of exerting direct cardioprotective effects through these mechanisms is unknown and is the subject of the current study. Anaesthetized C57BL/6 male mice were subjected to in situ 30 min. of regional myocardial ischaemia and 120 min. of reperfusion. The administration of an intravenous bolus of visfatin (5 x 10(-6) micromol) at the time of myocardial reperfusion reduced the myocardial infarct size from 46.1+/-4.1% in control hearts to 27.3+/-4.0% (n>or= 6/group, P<0.05), an effect that was blocked by the PI3K inhibitor, wortmannin, and the MEK1/2 inhibitor, U0126 (48.8+/-5.5% and 45.9+/-8.4%, respectively, versus 27.3+/-4.0% with visfatin; n>or= 6/group, P<0.05). In murine ventricular cardiomyocytes subjected to 30 min. of hypoxia followed by 30 min. of reoxygenation, visfatin (100 ng/ml), administered at the time of reoxygenation, reduced the cell death from 65.2+/-4.6% in control to 49.2+/-3.7%(n>200 cells/group, P<0.05), an effect that was abrogated by wortmannin and U0126 (68.1+/-5.2% and 59.7+/-6.2%, respectively; n>200 cells/group, P>0.05). Finally, the treatment of murine ventricular cardiomyocytes with visfatin (100 ng/ml) delayed the opening of the mPTP induced by oxidative stress from 81.2+/-4 sec. in control to 120+/-7 sec. (n>20 cells/group, P<0.05) in a PI3K- and MEK1/2-dependent manner. We report that the adipocytokine, visfatin, is capable of reducing myocardial injury when administered at the time of myocardial reperfusion in both the in situ murine heart and the isolated murine cardiomyocytes. The mechanism appears to involve the PI3K and MEK1/2 pathways and the mPTP.

Temporal changes in myocardial salvage kinases during reperfusion following ischemia: studies involving the cardioprotective adipocytokine apelin.

INTRODUCTION: Activation of the Reperfusion Injury Salvage Kinase (RISK) pathway, which incorporates phosphatidylinositol-3-OH kinase (PI3K)-Akt/protein kinase B (PKB) and p44/42 mitogen-activated protein kinase (MAPK), underlies protection against ischemia-reperfusion (I/R) injury. The temporal nature of the activation of these RISK pathway components during reperfusion is, however, uncertain. We examined Akt and p44/42 phosphorylation in hearts subjected to ischemia and varying periods of reperfusion in the absence or presence of the putative cardioprotectant, apelin-13. Akt activity was also measured. MATERIALS AND METHODS: Langendorff perfused C57Bl/6J mouse hearts were subjected to 35 min global ischemia followed by 0, 2.5, 5 or 10 min reperfusion with or without 1 microM apelin-13. Basal and apelin-induced phosphorylation of Akt (at both the threonine 308 and serine 473 phosphorylation sites) and p44/42 during the reperfusion phase was determined by Western blotting and Akt activity measured using an Enzyme-Linked ImmunoSorbent Assay (ELISA). RESULTS: Basal phosphorylation of both Akt and p44/42 increased progressively with time of reperfusion. Apelin enhanced Akt and p44/42 phosphorylation at all reperfusion time points. Akt activity did not change under basal conditions but was increased by apelin at 5 min (NS) and 10 min (p<0.05) reperfusion. DISCUSSION: We conclude that under basal conditions Akt and p44/42 phosphorylation increases with time of reperfusion but that this is not accompanied by increased kinase (Akt) activity. On application of a cardioprotectant, however, kinase phosphorylation and activity are enhanced suggesting that it is the combination of these two mechanisms that may underly the tissue preserving actions of such agents.

Necrostatin: a potentially novel cardioprotective agent?

BACKGROUND: Necrostatin-1 (Nec-1), a small tryptophan-based molecule, was recently reported to protect the cerebral cortex against ischemia-reperfusion (I/R) injury. We investigated the actions of Nec-1 and its so-called inactive analog, Nec-1i, in the setting of myocardial I/R injury. MATERIALS AND METHODS: The actions of Nec-1 and Nec-1i were examined in cultured C2C12 and H9c2 myocytes, cardiomyocytes isolated from male Sprague-Dawley rats, Langendorff isolated perfused C57Bl/6J mouse hearts and an in vivo open-chest C57Bl/6J mouse heart model. RESULTS: Nec-1 at 30 microM and 100 microM (but not 100 microM Nec-1i) reduced peroxide-induced cell death in C2C12 cells from 51.2 +/- 1.1% (control) to 26.3 +/- 2.9% (p < 0.01 vs control) and 17.8 +/- 0.9% (p < 0.001), respectively. With H9c2 cells cell death was also reduced from 73.0 +/- 0.4% (control) to 56.7 +/- 0% (30 microM Nec-1, p < 0.05) and 45.4 +/- 3.3% (100 microM Nec-1, p < 0.01). In the isolated perfused heart Nec-1 (30 microM) reduced infarct size (calculated as a percentage of the risk area) from 48.0 +/- 2.0% (control) to 32.1 +/- 5.4% (p < 0.05). Nec-1i (30 microM) also reduced infarct size (32.9 +/- 5.1%, p < 0.05). In anesthetized C57Bl/6J mice Nec-1 (1.65 mg/kg), given intraperitoneally to coincide with reperfusion following left anterior descending artery ligation (30 min), also reduced infarct size from 45.3 +/- 5.1% (control) to 26.6 +/- 4.0% (p < 0.05), whilst Nec-1i (1.74 mg/kg) was ineffective (37.8 +/- 6.0%). Stimulus-induced opening of the mitochondrial permeability transition pore (MPTP) in rat cardiomyocytes, as reflected by the time until mitochondrial depolarisation, was unaffected by Nec-1 or Nec-1i at 30 muM but increased at 100 muM i.e. 91% (p < 0.05 vs control) and 152% (p < 0.001) for Nec-1 and Nec-1i, respectively. CONCLUSION: This is the first study to demonstrate that necrostatins inhibit myocardial cell death and reduce infarct size, possibly via a mechanism independent of the MPTP.

Apelin-13 and apelin-36 exhibit direct cardioprotective activity against ischemia-reperfusion injury.

Protection against myocardial ischemia-reperfusion (I/R) injury involves activation of phosphatidylinositol-3-OH kinase (PI3K)- Akt/protein kinase B and p44/42 mitogen-activated protein kinase (MAPK), components of the reperfusion injury salvage kinase (RISK) pathway. The adipocytokine, apelin, activates PI3K-Akt and p44/42 in various tissues and we, therefore, hypothesised that it might demonstrate cardioprotective activity. Employing both in vivo (open-chest) and in vitro (Langendorff and cardiomyocytes) rodent (mouse and rat) models ofmyocardial I/R injury we investigated if apelin administered at reperfusion at concentrations akin to pharmacological doses possesses cardioprotective activity. Apelin-13 and the physiologically less potent peptide, apelin-36, decreased infarct size in vitro by 39.6% (p<0.01) and 26.1% (p<0.05) respectively. In vivo apelin-13 and apelin-36 reduced infarct size by 43.1% (p<0.01) and 32.7% (p<0.05). LY294002 and UO126, inhibitors of PI3K-Akt and p44/42 phosphorylation respectively, abolished the protective effects of apelin-13 in vitro.Western blot analysis provided further evidence for the involvement of PI3K-Akt and p44/42 in the cardioprotective actions of apelin. In addition,mitochondrial permeability transition pore (MPTP) opening was delayed by both apelin- 13 (127%, p<0.01) and apelin-36 (93%, p<0.01) which, in the case of apelin-13, was inhibited by LY294002 and mitogen-activated protein kinase kinase (MEK) inhibitor 1. This is the first study to yield evidence that the adipocytokine, apelin, produces direct cardioprotective actions involving the RISK pathway and the MPTP.

Native and oxidized low-density lipoproteins modulate the vasoactive actions of soluble beta-amyloid peptides in rat aorta.

Cerebrovascular accumulation of Abeta (beta-amyloid) occurs in aging and AD (Alzheimer's disease). Hypercholesterolaemia, which is associated with raised plasma LDL (low-density lipoprotein), may predispose to AD. Soluble Abeta is found in the circulation and enhances vasoconstriction. Under conditions that may favour the formation of short Abeta oligomers, as opposed to more severe polymerization leading to Abeta fibrillogenesis, we investigated the influence of LDLs on the vasoactive actions of soluble Abeta. Thus the actions of Abeta40 and Abeta42 in combination with native or oxidized LDL on vasoconstriction to NA (noradrenaline) and vasodilatation to ACh (acetylcholine) were examined in rat aortic rings. LDL, particularly when oxidized, potentiated NA-induced constriction when combined with soluble Abeta40 and, especially, Abeta42. Soluble Abeta40 reduced relaxation induced by ACh, but Abeta42 was ineffective. Native and oxidized LDL also attenuated relaxation. Synergism occurred between oxidized LDL and Abeta with respect to ACh-induced relaxation, but not between native LDL and Abeta. We have shown for the first time that, under conditions that may result in Abeta oligomer formation, LDL, particularly when oxidized, modulates the vascular actions of soluble Abeta to extents greater than those reported previously for fibrillar Abeta preparations. Mechanisms whereby a treatable condition, namely hypercholesterolaemia, might contribute to the development of the cerebrovascular component of AD are indicated.

Exaggerated polymerisation of beta-amyloid 40 stimulated by plasma lipoproteins results in fibrillar Abeta preparations that are ineffective in promoting ADP-induced platelet aggregation.

The cytotoxic beta-amyloid peptide (Abeta) of Alzheimer's disease (AD) occurs in both plasma and platelets and may modulate platelet function. Its biological activity may relate to its fibril content and factors that promote Abeta fibrillogenesis, e.g., plasma lipoproteins could, therefore, have implications for Abeta action. We undertook a study in which structure-activity relationships were considered with respect to the actions of Abeta(1-40) on platelet function. Thus, the influence of soluble Abeta and various fibrillar Abeta preparations (0.1-10 microM) on platelet aggregation and endogenous 5-hydroxytryptamine (5-HT) efflux was investigated. Soluble Abeta(1-40) only enhanced platelet aggregation (+30%, P<0.05) and 5-HT release (+28%) stimulated by ADP (1 microM) at the highest concentration tested (10 microM). By contrast, fibrillar Abeta(1-40) at 1, 5 and 10 microM potentiated aggregation by 17.4%, 68.8% (P<0.05) and 99.5% (P<0.0001), respectively, and 5-HT efflux by 17.4%, 65% and 208% (P<0.001). Abeta(1-40) fibrils generated in the presence of native and oxidised very low-density lipoprotein (VLDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) yielded platelet responses that did not differ from those seen with the lipoproteins alone. These responses were markedly lower than those obtained with homogeneous Abeta fibrils. Our data indicate that homogeneous Abeta(1-40) fibrils are more potent than soluble Abeta(1-40) in promoting platelet reactivity and that interactions with plasma lipoproteins result in the formation of Abeta fibrils that are ineffective. We suggest that lipoproteins may interfere with the recognition of Abeta by appropriate platelet receptors and/or cause Abeta to assume an "overaggregated" biologically inert state.