Attenuation of Adverse Postinfarction Left Ventricular Remodeling with Empagliflozin Enhances Mitochondria-Linked Cellular Energetics and Mitochondrial Biogenesis

Sodium-glucose cotransporter 2 (SGLT2) inhibitors such as empagliflozin are known to reduce the risk of hospitalizations related to heart failure irrespective of diabetic state. Meanwhile, adverse cardiac remodeling remains the leading cause of heart failure and death in the USA. Thus, understanding the mechanisms that are responsible for the beneficial effects of SGLT2 inhibitors is of the utmost relevance and importance. Our previous work illustrated a connection between adverse cardiac remodeling and the regulation of mitochondrial turnover and cellular energetics using a short-acting glucagon-like peptide-1 receptor agonist (GLP1Ra). Here, we sought to determine if the mechanism of the SGLT2 inhibitor empagliflozin (EMPA) in ameliorating adverse remodeling was similar and/or to identify what differences exist, if any. To this end, we administered permanent coronary artery ligation to induce adverse remodeling in wild-type and Parkin knockout mice and examined the progression of adverse cardiac remodeling with or without EMPA treatment over time. Like GLP1Ra, we found that EMPA affords a robust attenuation of PCAL-induced adverse remodeling. Interestingly, unlike the GLP1Ra, EMPA does not require Parkin to improve/maintain mitochondria-related cellular energetics and afford its benefits against developing adverse remodeling. These findings suggests that further investigation of EMPA is warranted as a potential path for developing therapy against adverse cardiac remodeling for patients that may have Parkin and/or mitophagy-related deficiencies.

Intermittent Use of a Short-Course Glucagon-like Peptide-1 Receptor Agonist Therapy Limits Adverse Cardiac Remodeling via Parkin-dependent Mitochondrial Turnover

Given that adverse remodeling is the leading cause of heart failure and death in the USA, there is an urgent unmet need to develop new methods in dealing with this devastating disease. Here we evaluated the efficacy of a short-course glucagon-like peptide-1 receptor agonist therapy-specifically 2-quinoxalinamine, 6,7-dichloro-N-(1,1-dimethylethyl)-3-(methylsulfonyl)-,6,7-dichloro-2-methylsulfonyl-3-N-tert-butylaminoquinoxaline (DMB; aka Compound 2) - in attenuating adverse LV remodeling. We also examined the role, if any, of mitochondrial turnover in this process. Wild-type, Parkin knockout and MitoTimer-expressing mice were subjected to permanent coronary artery ligation, then treated briefly with DMB. LV remodeling and cardiac function were assessed by histology and echocardiography. Autophagy and mitophagy markers were examined by western blot and mitochondrial biogenesis was inferred from MitoTimer protein fluorescence and qPCR. We found that DMB given post-infarction significantly reduced adverse LV remodeling and the decline of cardiac function. This paralleled an increase in autophagy, mitophagy and mitochondrial biogenesis. The salutary effects of the drug were lost in Parkin knockout mice, implicating Parkin-mediated mitophagy as part of its mechanism of action. Our findings suggest that enhancing Parkin-associated mitophagy and mitochondrial biogenesis after infarction is a viable target for therapeutic mitigation of adverse remodeling.

Abstract 395: Pioglitazone and Glucagon-like Peptide 1 Receptor Agonist Mitigate Adverse Postinfarction Left Ventricular Remodeling in Lean Mice When Administered After the Infarct Independent of Changes in Infarct Size

Pioglitazone (PIO) and GLP-1R receptor agonist (GLP1Ra) have been shown to be cardioprotective against ischemic cardiac injury. Much less is known about the effects of these agents on adverse post-MI LV remodeling. Based on our earlier findings that PIO and a GLP1Ra stimulate mitochondrial turnover, we evaluated the effects of these agents on post-MI remodeling. Lean mice underwent permanent coronary artery ligation (PCAL) to ensure that remodeling would be independent of changes in infarct size. Vehicle, PIO and GLP1Ra (Sigma) were administered i.p. 2h after the infarct and then every other day for a total of 6 doses. Echo and histology (Masson’s trichrome) were used to assess LV remodeling 30 days post-MI (late phase); immune cell infiltration was assessed 7 days after PCAL (early phase) via hematoxylin and eosin (H&E) staining. Both PIO and GLP1Ra were associated with significant improvements in ejection fraction and fractional shortening (A); however, at the dose used, neither drug restored function to that of the sham-operated mice (EF 60% and FS 30%, data not shown). GLP1Ra-treated mice exhibited a marked reduction in immune cell infiltration at 7d after PCAL (B), and fibrosis at 30d (C) compared to vehicle or PIO. While PIO had no effect on immune-cell infiltration and fibrosis, it was effective in attenuating post-MI remodeling. While sharing a common endpoint of attenuating adverse remodeling, the finding that PIO stimulates mitochondrial biogenesis and GLP1Ra induces mitophagy may help explain their disparate findings with respect to early phase remodeling.

Abstract 398: GLP-1 Receptor Agonist Administered After the Infarct Suppresses miR-33 Expression in Lean Mice Subjected to Permanent Coronary Artery Occlusion

MicroRNAs (miRs) regulate post-transcriptional gene expression and protein translation. There is now increasing evidence that miRs regulate mitochondrial turnover. miR-33 regulates cholesterol metabolism and mitochondrial function in cardiac fibroblasts and macrophages and has been implicated in promoting fibrosis. Excessive fibrosis contributes to the development of adverse LV remodeling. Given our recent findings that a glucagon-like peptide-1 receptor agonist (GLP1Ra) [Sigma] induces mitophagy and mitigates post-MI LV remodeling, the purpose of this study was to determine its effects on miR-33 expression after MI. We analyzed miR-33 expression in the viable regions of hearts in lean mice after permanent coronary arterial ligation (PCAL) and subsequent treatment with GLP1Ra administered 2h and 48h after the infarction (total of 2 doses). PCAL was associated with a marked increase in miR-33 that peaked at day 3 (data not shown). In the presence of GLP1Ra, miR-33 expression was suppressed 3 days post-PCAL ( A ). Polysome profiling revealed that miR-33 was decreased in the translating fractions of GLP1Ra-treated mice and increased in the non-translating fraction (80S free ribosomes) compared to vehicle ( B and C ). Decreased association of miR-33 with polysomes in GLP1Ra-treated mice would allow for increased target translation. Given that suppression of miR-33 is implicated in promoting fibrosis, a suppression of this miR by acute GLP1Ra treatment could explain the beneficial effects of this drug in limiting adverse cardiac remodeling.

Abstract 523: Pioglitazone and Glucagon-like Peptide 1 Receptor Agonist Stimulate Mitochondrial Turnover in the Heart When Administered After the Infarct in Obese Mice

Randomized clinical trials have demonstrated that pioglitazone (PIO), a thiazolidinedione, and liraglutide and semaglutide, glucagon-like peptide-1 receptor agonists (GLP1Ra), are effective in treating Type 2 diabetes mellitus. Of considerable interest is the additional observation that they may also be effective in reducing the incidence of major adverse cardiovascular events (MACE) independent of glycemic control. The mechanism underlying this protection is unknown. To test the hypothesis that enhanced mitochondrial turnover (mitophagy and mitochondrial biogenesis) might play a role, obese mice with insulin resistance were subjected to permanent coronary artery ligation (PCAL). Two hours later they were administered an i.p. bolus of vehicle (50μL DMSO), PIO (10mg/kg), or a GLP1Ra (10nmoles/25g) (Sigma). This was repeated every other day for 2 weeks. Hearts were probed by western blot for markers of mitochondrial biogenesis and mitophagy. As shown, PIO was a strong inducer of mitochondrial biogenesis evidenced by increased mitochondrial markers in the whole lysate (mitochondrial biogenesis) whereas GLP1Ra stimulated mitophagy, indicated by Parkin, p62 and optineurin translocation to the mitochondrial fraction. These findings suggest that enhanced mitochondrial biogenesis and mitophagy may be important therapeutic targets for the prevention of adverse cardiovascular outcomes. If confirmed, enhanced mitochondrial turnover may be one of the mechanisms underlying the reduced incidence of MACE that was observed in the PROactive (PIO) and the LEADER and SUSTAIN-6 (GLP1Ra) clinical trials.

Abstract 529: Asporin - Extracellular Matrix Protein Mitigates Pathological Remodeling

The cardiac extracellular matrix is a complex network of proteins and plays a key role in cardiac remodeling after myocardial infarction. One of the extracellular matrix proteins, asporin, is a member of the SLRP family and inhibits TGFβ signaling. However, very little is known about the function and regulation of asporin in cardiac remodeling. Using bioinformatics approach, microarray data analysis from publicly available datasets identified asporin as a top candidate showing an increase in left ventricle tissue with ischemic cardiomyopathy as compared to control donor hearts. To confirm, we detected an increase in asporin expression in paired heart biopsies taken before and after cardiopulmonary bypass surgery by western blot analysis. Our group showed that glucagon like receptor 1 agonist (GLP-1Ra) is beneficial for cardiac remodeling and prevents fibrosis. In a permanent coronary artery ligation model, we found increased extracellular asporin expression after 30 days in border zone and scar area with GLP-1Ra treatment compared to vehicle-treatment. To further elucidate the mechanism of asporin secretion, we used H9c2 cells as well as left ventricle tissue from mice and found that asporin was predominantly present in the heavy membrane enriched fraction (8,000xg pellet from postnuclear supernatant). Sequence analysis of asporin protein using SecretomeP 2.0 server predicted asporin might use the non-conventional form of secretion (secretory autophagy). Differentiation of H9c2 cells is accompanied by autophagy and mitochondrial biogenesis, and we found that the abundance of asporin in total lysate and heavy membrane fraction decreased suggesting it could be released via secretory autophagy. Using recombinant human asporin, we demonstrated that asporin stimulates an increase in LC3 and p62 in parallel to a decrease in COX IV and SMAD2 phosphorylation, indicating mitophagy induction and a decrease in TGFβ signaling. Based on our preliminary data and sequence comparison to a previously reported human peptide, we developed a rodent asporin peptide which is predicted to induce mitophagy while decreasing TGFβ signaling to prevent fibrosis. Studies are ongoing to establish the clinical relevance of asporin in animal models of ischemic injury.

Autophagosome formation is required for cardioprotection by chloramphenicol

AIMS

Chloramphenicol (CAP), a broad spectrum antibiotic, was shown to protect the heart against ischemia/reperfusion (I/R) injury. CAP also induces autophagy, however, it is not known whether CAP-induced cardioprotection is mediated by autophagy. Therefore, here we aimed to assess whether activation of autophagy is required for the infarct size limiting effect of CAP and to identify which component of CAP-induced autophagy contributes to cardioprotection against I/R injury.

MAIN METHODS

Hearts of Sprague-Dawley rats were perfused in Langendorff mode with Krebs-Henseleit solution containing either vehicle (CON), 300μM CAP (CAP), CAP and an inhibitor of autophagosome-lysosome fusion chloroquine (CAP+CQ), or an inhibitor of autophagosome formation, the functional null mutant TAT-HA-Atg5^K130R protein (CAP+K130R), and K130R or CQ alone, respectively. After 35min of aerobic perfusion, hearts were subjected to 30min global ischemia and 2h reperfusion. Autophagy was determined by immunoblot against LC3 from left atrial tissue. Infarct size was measured by TTC staining, coronary flow was measured, and the release of creatine kinase (CK) was assessed from the coronary effluent.

KEY FINDINGS

CAP treatment induced autophagy, increased phosphorylation of Erk1/2 in the myocardium and significantly reduced infarct size and CK release. Autophagy inhibitor TAT-HA-Atg5^K130R abolished cardioprotection by CAP, while in CAP+CQ hearts infarct size and CK release were reduced similarly to as seen in the CAP-treated group.

CONCLUSION

This is the first demonstration that autophagosome formation but not autophagosomal clearance is required for CAP-induced cardioprotection.

SIGNIFICANCE

Inducing autophagy sequestration might yield novel therapeutic options against acute ischemia/reperfusion injury.

Mitophagy and mitochondrial biogenesis in atrial tissue of patients undergoing heart surgery with cardiopulmonary bypass

Mitophagy occurs during ischemia/reperfusion (I/R) and limits oxidative stress and injury. Mitochondrial turnover was assessed in patients undergoing cardiac surgery involving cardiopulmonary bypass (CPB). Paired biopsies of right atrial appendage before initiation and after weaning from CPB were processed for protein analysis, mitochondrial DNA/nuclear DNA ratio (mtDNA:nucDNA ratio), mtDNA damage, mRNA, and polysome profiling. Mitophagy in the post-CPB samples was evidenced by decreased levels of mitophagy adapters NDP52 and optineurin in whole tissue lysate, decreased Opa1 long form, and translocation of Parkin to the mitochondrial fraction. PCR analysis of mtDNA comparing amplification of short vs. long segments of mtDNA revealed increased damage following cardiac surgery. Surprisingly, a marked increase in several mitochondria-specific protein markers and mtDNA:nucDNA ratio was observed, consistent with increased mitochondrial biogenesis. mRNA analysis suggested that mitochondrial biogenesis was traniscription independent and likely driven by increased translation of existing mRNAs. These findings demonstrate in humans that both mitophagy and mitochondrial biogenesis occur during cardiac surgery involving CPB. We suggest that mitophagy is balanced by mitochondrial biogenesis during I/R stress experienced during surgery. Mitigating mtDNA damage and elucidating mechanisms regulating mitochondrial turnover will lead to interventions to improve outcome after I/R in the setting of heart disease.

Myocardial Protection in Heart Surgery

One of the unmet clinical needs in heart surgery is the prevention of myocardial stunning and necrosis that occurs as a result of ischemia-reperfusion. Myocardial stunning, a frequent consequence after heart surgery, is characterized by a requirement for postoperative inotropic support despite a technically satisfactory heart operation. In high-risk patients with marginal cardiac reserve, stunning is a major cause of prolonged critical care and may be associated with as much as a 5-fold increase in mortality. In contrast, the frequency of myocardial necrosis (myocardial infarction [MI]) after cardiac surgery is less appreciated and its consequences are much more subtle. The consequences may not be apparent for months to years. While we now have a much better understanding of the molecular mechanisms underlying myocardial stunning and MI, we still have no effective way to prevent these complications, nor a consistently effective means to engage the well-studied endogenous mechanisms of cardioprotection. The failure to develop clinically effective interventions is multifactorial and can be attributed to reliance on findings obtained from subcellular and cellular studies, to drawing conclusions from preclinical large animal studies that have been conducted in a disease-free state, and to accepting less than robust surrogate markers of injury in phase II clinical trials. These factors also explain the disappointing failure to identify effective adjuvant therapy in the setting of percutaneous coronary revascularization for acute MI (AMI) and reperfusion injury. These issues have contributed to the disappointing outcomes of large and costly phase III trials, resulting in a lack of enthusiasm on the part of the pharmaceutical industry to engage in further drug development for this indication. The purpose of this review is to (1) define the scope of the clinical problem; (2) summarize the outcomes of selected phases II and III clinical trials; and (3) identify the gap that needs to be closed in order to address the unmet clinical need.

Celiac Artery Compression Syndrome: Report of a Case and Review of Current Opinion

The celiac artery compression syndrome (or median arcuate ligament syn drome) is characterized by postprandial abdominal pain, an epigastric bruit, and arteriographic evidence of significant extrinsic compression of the celiac artery. Although the concept of extrinsic compression of vessels is well estab lished in vascular surgery, the existence of the celiac artery compression syn drome has been a matter of controversy. A patient relieved of celiac artery compression and postprandial pain is presented. A review of the controversy and an approach to evaluating patients suspected of having this type of com pression is outlined.

Discordant signaling and autophagy response to fasting in hearts of obese mice: Implications for ischemia tolerance

Autophagy is regulated by nutrient and energy status and plays an adaptive role during nutrient deprivation and ischemic stress. Metabolic syndrome (MetS) is a hypernutritive state characterized by obesity, dyslipidemia, elevated fasting blood glucose levels, and insulin resistance. It has also been associated with impaired autophagic flux and larger-sized infarcts. We hypothesized that diet-induced obesity (DIO) affects nutrient sensing, explaining the observed cardiac impaired autophagy. We subjected male friend virus B NIH (FVBN) mice to a high-fat diet, which resulted in increased weight gain, fat deposition, hyperglycemia, insulin resistance, and larger infarcts after myocardial ischemia-reperfusion. Autophagic flux was impaired after 4 wk on a high-fat diet. To interrogate nutrient-sensing pathways, DIO mice were subjected to overnight fasting, and hearts were processed for biochemical and proteomic analysis. Obese mice failed to upregulate LC3-II or to clear p62/SQSTM1 after fasting, although mRNA for LC3B and p62/SQSTM1 were appropriately upregulated in both groups, demonstrating an intact transcriptional response to fasting. Energy- and nutrient-sensing signal transduction pathways [AMPK and mammalian target of rapamycin (mTOR)] also responded appropriately to fasting, although mTOR was more profoundly suppressed in obese mice. Proteomic quantitative analysis of the hearts under fed and fasted conditions revealed broad changes in protein networks involved in oxidative phosphorylation, autophagy, oxidative stress, protein homeostasis, and contractile machinery. In many instances, the fasting response was quite discordant between lean and DIO mice. Network analysis implicated the peroxisome proliferator-activated receptor and mTOR regulatory nodes. Hearts of obese mice exhibited impaired autophagy, altered proteome, and discordant response to nutrient deprivation.

Abstract 110: Activation of the Homeostatic Intracellular Response Leads to Increased Myocardial Mitochondrial Turnover in Patients Undergoing Cardiac Surgery

Background: Previously we showed that the homeostatic intracellular repair response (HIR2) is activated in the hearts of patients undergoing cardiac surgery. Autophagy is a principal component of this beneficial response that clears fragile mitochondria and protein aggregates. Moreover, we have previously shown that mitochondrial elimination through autophagy (mitophagy) is a key element in ischemic preconditioning. Thus, an important mechanism of cardioprotection appears to involve the upregulation of autophagy which facilitates the clearance of vulnerable mitochondria to limit I/R injury. We hypothesized that this protective action leads to turnover of the existing mitochondrial population in the heart during the resolution of I/R injury. The purpose of this study was to examine if the mechanism of HIR2 extends to remodeling the existing mitochondrial population of the heart.

Study Design: Autophagy and mitochondrial turnover were assessed in 10 patients undergoing coronary artery bypass or valve surgery requiring cardiopulmonary bypass. Biopsies of the right atrial appendage obtained before initiation and after weaning from cardiopulmonary bypass were processed to yield whole tissue lysates and mitochondria-enriched heavy membrane fractions. Samples were analyzed for autophagy by immunoblotting for LC3, Beclin-1, ATG5-12, and p62. Mitochondrial turnover was assessed by monitoring Tom70, Cox4, Drp1, p62 and Parkin in tissue lysates and heavy membrane fractions.

Results: Heart surgery was associated with a robust increase in autophagy indicated by depletion of LC3, Beclin-1, ATG5-12 and p62, as well as the mitophagy and fission regulator Drp1. Parkin increased in the mitochondrial fraction after bypass. Surprisingly, post-bypass tissue lysates showed a marked increase in mitochondrial markers Tom70 and Cox4, suggesting mitochondrial biogenesis.

Conclusions: These findings provide evidence for the first time in humans that coordinated mitophagy and biogenesis are part of the homeostatic response to I/R, pointing to the importance of studying this aspect of HIR2. Strategies designed to amplify HIR2 during cardiac stress may represent an entirely new approach to myocardial protection in patients undergoing heart surgery.

This old heart: Cardiac aging and autophagy

Autophagy, a cellular housekeeping process, is essential to maintain tissue homeostasis, particularly in long-lived cells such as cardiomyocytes. Autophagic activity declines with age and may explain many features of age-related cardiac dysfunction. In this review we summarize the current state of knowledge regarding age-related changes in autophagy in the heart. Recent findings from studies in human hearts are presented, including evidence that the autophagic response is intact in the aged human heart. Impaired autophagic clearance of protein aggregates or deteriorating mitochondria will have multiple consequences including increased arrhythmia risk, decreased contractile function, reduced tolerance to ischemic stress, and increased inflammation; thus autophagy represents a potentially important therapeutic target to mitigate the cardiac consequences of aging. This article is part of a Special Issue entitled CV Aging.

Abstract 219: Cardiac Autophagy in Response to Fasting is Impaired in Mice with Metabolic Syndrome

Introduction: Macroautophagy (autophagy) is highly responsive to nutrient/energy status and cellular stress. It plays an adaptive role in limiting ischemia/reperfusion (I/R) injury in the heart. Nutrient depletion is a potent inducer of autophagy and is mediated by reciprocal regulation of AMPK and mTOR pathways which in turn regulate autophagy initiation via ULK1/Atg1. Autophagy is reduced in the setting of obesity, dyslipidemia, and insulin resistance associated with metabolic syndrome (MetS). The purpose of this study was determine whether impaired autophagy in MetS is due to altered upstream signaling or a disruption in the autophagic pathway.

Methods: Mice were ad-lib fed a chow (Lean) or a high fat diet (HFD) (D12492, 60% fat) for 18 weeks. In both groups, half of the mice were freely fed with the other half fasted for 24 hours prior to cardiac harvest. Protein levels were determined with Western blotting and gene expression with quantitative PCR.

Results: Consistent with previous data, HFD animals exhibited obesity and insulin resistance as reflected by increased body weight, and elevated serum insulin/HOMA compared to Lean animals. Fasting resulted in a marked reduction in serum insulin in both Lean (p=0.013) and HFD (p =0.002) animals. This was accompanied by marked increases in cardiac AMPK activation as reflected by increased phosphorylation in both Lean (p =0.002) and HFD (p=0.002) groups with parallel reciprocal suppression of mTOR activity as reflected by decreased pS6K and pS6. As expected, the Lean group exhibited a fasting-induced increase in LC3-II (p=0.020) indicating an increase in autophagy. This did not occur in the HFD group despite a similar induction in LC3B and p62 gene expression. This lack of autophagy stimulation with fasting in HFD animals was not explained by differences in autophagy initiation as the phosphorylation status of ULK1 decreased similarly with fasting in both groups.

Conclusions: These data indicate that the impairment of cardiac autophagy in the presence of MetS is not attributable to abnormal upstream nutrient sensing pathways. The findings suggest a MetS-associated defect in the autophagy/lysosomal fusion pathway. This could explain the increased vulnerability of the heart to I/R injury in the setting of MetS.

Cell-permeable protein therapy for complex I dysfunction

Complex I deficiency is difficult to treat because of the size and complexity of the multi-subunit enzyme complex. Mutations or deletions in the mitochondrial genome are not amenable to gene therapy. However, animal studies have shown that yeast-derived internal NADH quinone oxidoreductase (Ndi1) can be delivered as a cell-permeable recombinant protein (Tat-Ndi1) that can functionally replace complex I damaged by ischemia/reperfusion. Current and future treatment of disorders affecting complex I are discussed, including the use of Tat-Ndi1.

Autophagy: an affair of the heart

Whether an element of routine housekeeping or in the setting of imminent disaster, it is a good idea to get one’s affairs in order. Autophagy, the process of recycling organelles and protein aggregates, is a basal homeostatic process and an evolutionarily conserved response to starvation and other forms of metabolic stress. Our understanding of the role of autophagy in the heart is changing rapidly as new information becomes available. This review examines the role of autophagy in the heart in the setting of cardioprotection, hypertrophy, and heart failure. Contradictory findings are reconciled in light of recent developments. The preponderance of evidence favors a beneficial role for autophagy in the heart under most conditions.

Reduction of infarct size by the therapeutic protein TAT-Ndi1 in vivo

Lethal myocardial ischemia-reperfusion (I/R) injury has been attributed in part to mitochondrial respiratory dysfunction (including damage to complex I) and the resultant excessive production of reactive oxygen species. Recent evidence has shown that reduced nicotinamide adenine dinucleotide-quinone internal oxidoreductase (Ndi1; the single-subunit protein that in yeast serves the analogous function as complex I), transduced by addition of the TAT-conjugated protein to culture media and perfusion buffer, can preserve mitochondrial function and attenuate I/R injury in neonatal rat cardiomyocytes and Langendorff-perfused rat hearts. However, this novel metabolic strategy to salvage ischemic-reperfused myocardium has not been tested in vivo. In this study, TAT-conjugated Ndi1 and placebo-control protein were synthesized using a cell-free system. Mitochondrial uptake and functionality of TAT-Ndi1 were demonstrated in mitochondrial preparations from rat hearts after intraperitoneal administration of the protein. Rats were randomized to receive either TAT-Ndi1 or placebo protein, and 2 hours later all animals underwent 45-minute coronary artery occlusion followed by 2 hours of reperfusion. Infarct size was delineated by tetrazolium staining and normalized to the volume of at-risk myocardium, with all analysis conducted in a blinded manner. Risk region was comparable in the 2 cohorts. Preischemic administration of TAT-Ndi1 was profoundly cardioprotective. These results demonstrate that it is possible to target therapeutic proteins to the mitochondrial matrix and that yeast Ndi1 can substitute for complex I to ameliorate I/R injury in the heart. Moreover, these data suggest that cell-permeable delivery of mitochondrial proteins may provide a novel molecular strategy to treat mitochondrial dysfunction in patients.

Abstract 032: Impaired Cardiac Autophagy In Metabolic Syndrome Despite Intact AMPK And mTOR Signaling

Objective: We previously reported that basal cardiac autophagy is lower in the setting of metabolic syndrome (MetS) (obesity, dyslipidemia, insulin resistance) and is associated with attenuation of cardioprotection after ischemic preconditioning. To understand the underlying mechanisms and exclude effects of the extracellular milieu, we investigated the roles of two major cellular energy sensing pathways, adenosine monophosphate-activated protein kinase (AMPK), and mammalian target of rapamycin (mTOR), using adult rat ventricular cardiomyocytes (ARVM) isolated from Sprague Dawley (SD) and Zucker obese (ZO) rats.

Methods: ARVM were cultured overnight and subjected to nutrient deprivation (1 hr), or treated with 1µM phenformin (Ph), an AMPK activator, or 5µM rapamycin (Rap), an mTOR inhibitor. Immunoblotting was used to measure phosphorylation of AMPK, p70S6 kinase (a downstream target of mTOR), LC3-I, -II, and p62 (autophagic clearance).

Results: In ARVM from SD rats, starvation or Ph increased p-AMPK and decreased p-p70S6K, accompanied by increased LC3-II and 50% reduction in p62. Rapamycin decreased phosphorylation of p70S6K, increased LC3-II and decreased p62. In ZO ARVM, Ph and Rap also activated AMPK and inhibited mTOR; however, LC3-II was unchanged (Fig.) and p62 clearance was blunted.

Conclusions: Despite appropriate activation of AMPK and inhibition of mTOR, autophagy is impaired in ARVM from ZO rats. These cells retain the MetS phenotype, facilitating efforts to delineate the molecular basis of impaired autophagy and vulnerability to ischemia/reperfusion injury in MetS. This could lead to new approaches to myocardial protection in at-risk patients.

Activation of the homeostatic intracellular repair response during cardiac surgery

BACKGROUND

The homeostatic intracellular repair response (HIR2) is an endogenous beneficial pathway that eliminates damaged mitochondria and dysfunctional proteins in response to stress. The underlying mechanism is adaptive autophagy. The purpose of this study was to determine whether the HIR2 response is activated in the heart in patients undergoing cardiac surgery and to assess whether it is associated with the duration of ischemic arrest and predicted surgical outcomes.

STUDY DESIGN

Autophagy was assessed in 19 patients undergoing coronary artery bypass or valve surgery requiring cardiopulmonary bypass. Biopsies of the right atrial appendage obtained before initiation of cardiopulmonary bypass and after weaning from cardiopulmonary bypass were analyzed for autophagy by immunoblotting for LC3, Beclin-1, autophagy 5-12, and p62. Changes in p62, a marker of autophagic flux, were correlated with duration of ischemia and with the mortality/morbidity risk scores obtained from the Society of Thoracic Surgeons Adult Cardiac Surgery Database (version 2.73).

RESULTS

Heart surgery was associated with a robust increase in autophagic flux indicated by depletion of LC3-I, LC3-II, Beclin-1, and autophagy 5-12; the magnitude of change for each of these factors correlated significantly with changes in the flux marker p62. In addition, changes in p62 correlated directly with cross-clamp time and inversely with the mortality and morbidity risk scores.

CONCLUSIONS

These findings are consistent with preclinical studies indicating that HIR2 is cardioprotective and reveal that it is activated in patients in response to myocardial ischemic stress. Strategies designed to amplify HIR2 during conditions of cardiac stress might have a therapeutic use and represent an entirely new approach to myocardial protection in patients undergoing heart surgery.

Under-prescribing and non-adherence to medications after coronary bypass surgery in older adults: strategies to improve adherence

The focus for this clinical review is under-prescribing and non-adherence to medication guidelines in older adults after coronary artery bypass grafting (CABG) surgery. Non-adherence occurs in all age groups, but older adults have a unique set of challenges including difficulty hearing, comprehending, and remembering instructions; acquiring and managing multiple medications; and tolerating drug-drug and drug-disease interactions. Still, non-adherence leads to increased morbidity, mortality, and costs to the healthcare system. Factors contributing to non-adherence include failure to initiate therapy before hospital discharge; poor education about the importance of each medication by hospital staff; poor education about medication side effects; polypharmacy; multiple daily dosing; excessive cost; and the physician's lack of knowledge of clinical indicators for use of medications. To improve adherence, healthcare systems must ensure that (i) all patients are prescribed the appropriate medications at discharge; (ii) patients fill and take these medications post-operatively; and (iii) patients continue long-term use of these medications. Interventions must target central administrative policies within healthcare institutions, the difficulties facing providers, as well as the concerns of patients. Corrective efforts need to be started early during the hospitalization and involve practitioners who can follow patients after the date on which surgical care is no longer needed. A solid, ongoing relationship between patients and their primary-care physicians and cardiologists is essential. This review summarizes the post-operative medication guidelines for CABG surgery, describes barriers that limit the adherence to these guidelines, and suggests possible avenues to improve medication adherence in older cardiac surgery patients.

Impaired mitophagy at the heart of injury

Recent publications link mitophagy mediated by PINK1 and Parkin with cardioprotection and attenuation of inflammation and cell death. The field is in need of methods to monitor mitochondrial turnover in vivo to support the development of new therapies targeting mitochondrial turnover.

Abstract P066: Imaging Autophagy in Living Mice

Autophagy is a homeostatic response to cellular stress. It has been shown to be potently upregulated in the heart in response to a variety of interventions. However, to date, it has not been possible to monitor autophagy without sacrificing the animal. Here we report the use of the Caliper Life Sciences Spectrum In Vivo Imaging System (IVIS) to image autophagy in homozygous transgenic mice expressing mCherryLC3 under control of the alpha myosin heavy chain promoter. Autophagy was stimulated by the administration of rapamycin (2mg/kg), and autophagosomal flux was blocked by administration of chloroquine (10mg/kg) ip. Mice were imaged at baseline and four hours later, using a protocol of 3 acquisitions of 15 seconds each. Total flux was 3.19±0.72 before drug administration and 3.93+1.10 after 4 hr, p<;0.01, n=14. These results show for the first time imaging of autophagy in hearts of live mice.

Acute induction of autophagy as a novel strategy for cardioprotection: getting to the heart of the matter

There is no question that necrosis and apoptosis contribute to cardiomyocyte death in the setting of myocardial ischemia-reperfusion. Indeed, considerable effort and resources have been invested in the development of novel therapies aimed at attenuating necrotic and apoptotic cell death, with the ultimate goal of applying these strategies to reduce infarct size and improve outcome in patients suffering acute myocardial infarction (MI) or 'heart attack'. However, an issue that remains controversial is the role of autophagy in determining the fate of ischemic-reperfused cardiomyocytes: i.e., is induction of autophagy detrimental or protective? Recent data from our group obtained in the clinically relevant, in vivo swine model of acute MI provides novel evidence of a positive association between pharmacological upregulation of autophagy (achieved by administration of chloramphenicol succinate (CAPS)) and increased resistance to myocardial ischemia-reperfusion injury.

Cardioprotection through autophagy: ready for clinical trial?

Interventions that reduce infarct size in animal models have largely failed to improve outcome in patients suffering acute myocardial infarction (MI), or 'heart attack'. Our group recently reported a reduction of infarct size by chloramphenicol treatment in a porcine in vivo model of acute MI, through a mechanism involving the induction of autophagy. Since 2005 several studies have implicated autophagy as a target for cardioprotection.

Profound cardioprotection with chloramphenicol succinate in the swine model of myocardial ischemia-reperfusion injury

BACKGROUND

Emerging evidence suggests that "adaptive" induction of autophagy (the cellular process responsible for the degradation and recycling of proteins and organelles) may confer a cardioprotective phenotype and represent a novel strategy to limit ischemia-reperfusion injury. Our aim was to test this paradigm in a clinically relevant, large animal model of acute myocardial infarction.

METHODS AND RESULTS

Anesthetized pigs underwent 45 minutes of coronary artery occlusion and 3 hours of reperfusion. In the first component of the study, pigs received chloramphenicol succinate (CAPS) (an agent that purportedly upregulates autophagy; 20 mg/kg) or saline at 10 minutes before ischemia. Infarct size was delineated by tetrazolium staining and expressed as a % of the at-risk myocardium. In separate animals, myocardial samples were harvested at baseline and 10 minutes following CAPS treatment and assayed (by immunoblotting) for 2 proteins involved in autophagosome formation: Beclin-1 and microtubule-associated protein light chain 3-II. To investigate whether the efficacy of CAPS was maintained with "delayed" treatment, additional pigs received CAPS (20 mg/kg) at 30 minutes after occlusion. Expression of Beclin-1 and microtubule-associated protein light chain 3-II, as well as infarct size, were assessed at end-reperfusion. CAPS was cardioprotective: infarct size was 25±5 and 41±4%, respectively, in the CAPS-pretreated and CAPS-delayed treatment groups versus 56±5% in saline controls (P<0.01 and P<0.05 versus control). Moreover, administration of CAPS was associated with increased expression of both proteins.

CONCLUSIONS

Our results demonstrate attenuation of ischemia-reperfusion injury with CAPS and are consistent with the concept that induction of autophagy may provide a novel strategy to confer cardioprotection.

Autophagy induced by ischemic preconditioning is essential for cardioprotection

Based on growing evidence linking autophagy to preconditioning, we tested the hypothesis that autophagy is necessary for cardioprotection conferred by ischemic preconditioning (IPC). We induced IPC with three cycles of 5 min regional ischemia alternating with 5 min reperfusion and assessed the induction of autophagy in mCherry-LC3 transgenic mice by imaging of fluorescent autophagosomes in cryosections. We found a rapid and significant increase in the number of autophagosomes in the risk zone of the preconditioned hearts. In Langendorff-perfused hearts subjected to an IPC protocol of 3 x 5 min ischemia, we also observed an increase in autophagy within 10 min, as assessed by Western blotting for p62 and cadaverine dye binding. To establish the role of autophagy in IPC cardioprotection, we inhibited autophagy with Tat-ATG5(K130R), a dominant negative mutation of the autophagy protein Atg5. Cardioprotection by IPC was reduced in rat hearts perfused with recombinant Tat-ATG5(K130R). To extend the potential significance of autophagy in cardioprotection, we also assessed three structurally unrelated cardioprotective agents--UTP, diazoxide, and ranolazine--for their ability to induce autophagy in HL-1 cells. We found that all three agents induced autophagy; inhibition of autophagy abolished their protective effect. Taken together, these findings establish autophagy as an end-effector in ischemic and pharmacologic preconditioning.

Autophagy: definition, molecular machinery, and potential role in myocardial ischemia-reperfusion injury

Autophagy is the endogenous, tightly regulated cellular "housekeeping" process responsible for the degradation of damaged and dysfunctional cellular organelles and protein aggregates. There is a growing consensus that autophagy is upregulated in the setting of myocardial ischemia-reperfusion. Moreover, emerging data suggest that autophagy may serve as an adaptive process and confer increased resistance to ischemia-reperfusion injury. Our aims in this review are to (1) provide a brief synopsis of process of autophagy (including an overview of the key molecular mediators of this catabolic process and its relationship with other cardiac signaling pathways) and (2) most importantly, summarize the current evidence for versus against the intriguing concept of autophagy-mediated cardioprotection.

Autophagy during cardiac stress: joys and frustrations of autophagy

The study of autophagy has been transformed by the cloning of most genes in the pathway and the introduction of GFP-LC3 as a reporter to allow visual assessment of autophagy. The field of cardiac biology is not alone in attempting to understand the implications of autophagy. The purpose of this review is to address some of the controversies and conundrums associated with the evolving studies of autophagy in the heart. Autophagy is a cellular process involving a complex orchestration of regulatory gene products as well as machinery for assembly, selective targeting, and degradation of autophagosomes and their contents. Our understanding of the role of autophagy in human disease is rapidly evolving as investigators examine the process in different tissues and different pathophysiological contexts. In the field of heart disease, autophagy has been examined in the settings of ischemia and reperfusion, preconditioning, cardiac hypertrophy, and heart failure. This review addresses the role of autophagy in cardioprotection, the balance of catabolism and anabolism, the concept of mitochondrial quality control, and the implications of impaired autophagic flux or frustrated autophagy.

Autophagy and protein kinase C are required for cardioprotection by sulfaphenazole

Previously, we showed that sulfaphenazole (SUL), an antimicrobial agent that is a potent inhibitor of cytochrome P4502C9, is protective against ischemia-reperfusion (I/R) injury (Ref. 15). The mechanism, however, underlying this cardioprotection, is largely unknown. With evidence that activation of autophagy is protective against simulated I/R in HL-1 cells, and evidence that autophagy is upregulated in preconditioned hearts, we hypothesized that SUL-mediated cardioprotection might resemble ischemic preconditioning with respect to activation of protein kinase C and autophagy. We used the Langendorff model of global ischemia to assess the role of autophagy and protein kinase C in myocardial protection by SUL during I/R. We show that SUL enhanced recovery of function, reduced creatine kinase release, decreased infarct size, and induced autophagy. SUL also triggered PKC translocation, whereas inhibition of PKC with chelerythrine blocked the activation of autophagy in adult rat cardiomyocytes. In the Langendorff model, chelerythrine suppressed autophagy and abolished the protection mediated by SUL. SUL increased autophagy in adult rat cardiomyocytes infected with GFP-LC3 adenovirus, in isolated perfused rat hearts, and in mCherry-LC3 transgenic mice. To establish the role of autophagy in cardioprotection, we used the cell-permeable dominant-negative inhibitor of autophagy, Tat-Atg5(K130R). Autophagy and cardioprotection were abolished in rat hearts perfused with recombinant Tat-Atg5(K130R). Taken together, these studies indicate that cardioprotection mediated by SUL involves a PKC-dependent induction of autophagy. The findings suggest that autophagy may be a fundamental process that enhances the heart's tolerance to ischemia.

Autophagy is required for preconditioning by the adenosine A1 receptor-selective agonist CCPA

We have shown that the cellular process of macroautophagy plays a protective role in HL-1 cardiomyocytes subjected to simulated ischemia/reperfusion (sI/R) (Hamacher-Brady et al. in J Biol Chem 281(40):29776-29787). Since the nucleoside adenosine has been shown to mimic both early and late phase ischemic preconditioning, a potent cardioprotective phenomenon, the purpose of this study was to determine the effect of adenosine on autophagosome formation. Autophagy is a highly regulated intracellular degradation process by which cells remove cytosolic long-lived proteins and damaged organelles, and can be monitored by imaging the incorporation of microtubule-associated light chain 3 (LC3) fused to a fluorescent protein (GFP or mCherry) into nascent autophagosomes. We investigated the effect of adenosine receptor agonists on autophagy and cell survival following sI/R in GFP-LC3 infected HL-1 cells and neonatal rat cardiomyocytes. The A(1) adenosine receptor agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA) (100 nM) caused an increase in the number of autophagosomes within 10 min of treatment; the effect persisted for at least 300 min. A significant inhibition of autophagy and loss of protection against sI/R measured by release of lactate dehydrogenase (LDH), was demonstrated in CCPA-pretreated cells treated with an A(1) receptor antagonist, a phospholipase C inhibitor, or an intracellular Ca(+2) chelator. To determine whether autophagy was required for the protective effect of CCPA, autophagy was blocked with a dominant negative inhibitor (Atg5(K130R)) delivered by transient transfection (in HL-1 cells) or protein transduction (in adult rat cardiomyocytes). CCPA attenuated LDH release after sI/R, but protection was lost when autophagy was blocked. To assess autophagy in vivo, transgenic mice expressing the red fluorescent autophagy marker mCherry-LC3 under the control of the alpha myosin heavy chain promoter were treated with CCPA 1 mg/kg i.p. Fluorescence microscopy of cryosections taken from the left ventricle 30 min after CCPA injection revealed a large increase in the number of mCherry-LC3-labeled structures, indicating the induction of autophagy by CCPA in vivo. Taken together, these results indicate that autophagy plays an important role in mediating the cardioprotective effects conferred by adenosine pretreatment.

Sodium-hydrogen exchange inhibition by cariporide to reduce the risk of ischemic cardiac events in patients undergoing coronary artery bypass grafting: results of the EXPEDITION study

BACKGROUND

The EXPEDITION study addressed the efficacy and safety of inhibiting the sodium hydrogen exchanger isoform-1 (NHE-1) by cariporide in the prevention of death or myocardial infarction (MI) in patients undergoing coronary artery bypass graft surgery. The premise was that inhibition of NHE-1 limits intracellcular Na accumulation and thereby limits Na/Ca-exchanger-mediated calcium overload to reduce infarct size.

METHODS

High-risk coronary artery bypass graft surgery patients (n = 5,761) were randomly allocated to receive either intravenous cariporide (180 mg in a 1-hour preoperative loading dose, then 40 mg per hour over 24 hours and 20 mg per hour over the subsequent 24 hours) or placebo. The primary composite endpoint of death or MI was assessed at 5 days, and patients were followed for as long as 6 months.

RESULTS

At 5 days, the incidence of death or MI was reduced from 20.3% in the placebo group to 16.6% in the treatment group (p = 0.0002). Paradoxically, MI alone declined from 18.9% in the placebo group to 14.4% in the treatment group (p = 0.000005), while mortality alone increased from 1.5% in the placebo group to 2.2% with cariporide (p = 0.02). The increase in mortality was associated with an increase in cerebrovascular events. Unlike the salutary effects that were maintained at 6 months, the difference in mortality at 6 months was not significant.

CONCLUSIONS

The EXPEDITION study is the first phase III myocardial protection trial in which the primary endpoint was achieved and proof of concept demonstrated. As a result of increased mortality associated with an increase in cerebrovascular events, it is unlikely that cariporide will be used clinically. The findings suggest that sodium hydrogen exchanger isoform-1 inhibition holds promise for a new class of drugs that could significantly reduce myocardial injury associated with ischemia-reperfusion injury.

Oxidative stress and adenosine A1 receptor activation differentially modulate subcellular cardiomyocyte MAPKs

The mechanism by which distinct stimuli activate the same mitogen-activated protein kinases (MAPKs) is unclear. We examined compartmentalized MAPK signaling and altered redox state as possible mechanisms. Adult rat cardiomyocytes were exposed to the adenosine A1 receptor agonist 2-chloro- N6-cyclopentyladenosine (CCPA; 500 nM) or H2O2 (100 μM) for 15 min. Nuclear/myofilament, cytosolic, Triton-soluble membrane, and Triton-insoluble membrane fractions were generated. CCPA and H2O2 activated p38 MAPK and p44/p42 ERKs in cytosolic fractions. In Triton-soluble membrane fractions, H2O2 activated p38 MAPK and p42 ERK, whereas CCPA had no effect on MAPK activation in this fraction. The greatest difference between H2O2 and CCPA was in the Triton-insoluble membrane fraction, where H2O2 increased p38 and p42 activation and CCPA reduced MAPK activation. CCPA also increased protein phosphatase 2A activity in the Triton-insoluble membrane fraction, suggesting that the activation of this phosphatase may mediate CCPA effects in this fraction. The Triton-insoluble membrane fraction was enriched in the caveolae marker caveolin-3, and >85% of p38 MAPK and p42 ERK was bound to this scaffolding protein in these membranes, suggesting that caveolae may play a role in the divergence of MAPK signals from different stimuli. The antioxidant N-2-mercaptopropionyl glycine (300 μM) reduced H2O2-mediated MAPK activation but failed to attenuate CCPA-induced MAPK activation. H2O2 but not CCPA increased reactive oxygen species (ROS). Thus the adenosine A1 receptor and oxidative stress differentially modulate subcellular MAPKs, with the main site of divergence being the Triton-insoluble membrane fraction. However, the adenosine A1 receptor-mediated MAPK activation does not involve ROS formation.

The Patient Safety in Surgery Study: Background, Study Design, and Patient Populations

BACKGROUND

The purpose of this article is to describe the background, design, and patient populations of the Patient Safety in Surgery Study, as a preliminary to the articles in this journal that will report the results of the Study.

STUDY DESIGN

The Patient Safety in Surgery Study was a prospective cohort study. Trained nurses collected preoperative risk factors, operative variables, and 30-day postoperative mortality and morbidity outcomes in patients undergoing major general and vascular operations at 128 Veterans Affairs (VA) medical centers and 14 selected university medical centers between October 1, 2001 and September 30, 2004. An Internet-based data collection system was used to input data from the different private medical centers. Semiannual feedback of observed to expected mortality and morbidity ratios was provided to the participating medical centers.

RESULTS

During the 3-year study, total accrual in general surgery was 145,618 patients, including 68.5% from the VA and 31.5% from the private sector. Accrual in vascular surgery totaled 39,225 patients, including 77.8% from the VA and 22.2% from the private sector. VA patients were older and included a larger proportion of male patients and African Americans and Hispanics. The VA population included more inguinal, umbilical, and ventral hernia repairs, although the private-sector population included more thyroid and parathyroid, appendectomy, and operations for breast cancer. Preoperative comorbidities were similar in the two populations, but the rates of comorbidities were higher in the VA. American Society of Anesthesiologists classification tended to be higher in the VA.

CONCLUSIONS

The National Surgical Quality Improvement Program methodology was successfully implemented in the 14 university medical centers. The data from the study provided the basis for the articles in this issue of the Journal of the American College of Surgeons.

Multivariable Predictors of Postoperative Cardiac Adverse Events after General and Vascular Surgery: Results from the Patient Safety in Surgery Study

BACKGROUND

Cardiac adverse events (CAEs) are relatively infrequent, but highly lethal, after noncardiac operations. The value of available risk scoring systems is uncertain and these systems can be outdated. We used the Patient Safety in Surgery Study database to develop and test a model to predict patient risk for CAEs after general and vascular surgical operations.

STUDY DESIGN

As part of the Patient Safety in Surgery Study, following the National Surgical Quality Improvement Program's protocol, multiple demographic, preoperative, perioperative, and outcomes variables were measured during a 3-year period. Data from 128 Veterans Affairs medical center hospitals and from 14 academic medical centers on 183,069 patients were used in a logistic regression analysis to model multivariable predictors of serious CAEs (cardiac arrest or acute myocardial infarction within 30 days of operation).

RESULTS

CAEs occurred in 2,362 patients (1.29%) and of these, 59.44% expired. Multivariable stepwise logistic regression identified 20 independent predictors of CAEs, which excluded most cardiac-specific risk factors. The most important multivariable predictors of CAE were American Society of Anesthesiologists physical status classification, work relative value units of the most complex procedure, age, and type of operation. A risk prediction scoring system using the logistic regression odds ratios proved to be a useful prediction tool when tested using a random sample from the database.

CONCLUSIONS

CAEs after noncardiac operations are relatively infrequent but highly lethal. Operation type and urgency and American Society of Anesthesiologists physical status assessment are important independent predictors of cardiac morbidity, but angina, recent MI, and earlier cardiac operation are not. A prediction scoring system based on the Patient Safety in Surgery Study multivariable odds ratios is likely to be predictive of future events in a similar population requiring noncardiac procedures. This risk model can also serve as a tool to measure quality and effectiveness of care by providers who perform noncardiac operations.

Effects of perioperative nesiritide in patients with left ventricular dysfunction undergoing cardiac surgery:the NAPA Trial

OBJECTIVES

The purpose of this study was to determine the role nesiritide might play in patients with left ventricular dysfunction undergoing coronary artery bypass grafting (CABG) using cardiopulmonary bypass (CPB).

BACKGROUND

Given the hemodynamic, neurohormonal, and renal effects of natriuretic peptides, nesiritide might be useful in the management of patients undergoing cardiac surgery.

METHODS

This prospective, double-blind, exploratory evaluation randomly assigned patients with ejection fraction </=40% who were undergoing CABG with anticipated use of CPB to receive either nesiritide or placebo, in addition to usual care, for 24 to 96 h after induction of anesthesia. Postoperative renal function, hemodynamics, and drug use (primary end points) were assessed in patients who underwent CABG using CPB; mortality and safety (secondary end points) were assessed in all patients who received the study drug.

RESULTS

Of 303 randomized patients, 279 received the study drug and 272 underwent CABG using CPB. Compared with placebo, nesiritide was associated with a significantly attenuated peak increase in serum creatinine (0.15 +/- 0.29 mg/dl vs. 0.34 +/- 0.48 mg/dl; p < 0.001) and a smaller fall in glomerular filtration rate (-10.8 +/- 19.3 ml/min/1.73 m(2) vs. -17.2 +/- 21.9 ml/min/1.73 m(2); p = 0.001) during hospital stay or by study day 14, and a greater urine output (2,926 +/- 1,179 ml vs. 2,350 +/- 1,066 ml; p < 0.001) during the initial 24 h after surgery. In addition, nesiritide-treated patients had a shorter hospital stay (p = 0.043) and lower 180-day mortality (p = 0.046).

CONCLUSIONS

Nesiritide in the setting of CABG with CPB is associated with improved postoperative renal function and possibly enhanced survival. (The NAPA Trial; ; ).

Successful management of recalcitrant groin lymphorrhoea with the combination of intraoperative lymphatic mapping and muscle flap

Recalcitrant groin lymphorrhoea in high-risk patients remains a problem. In this report, a cardiac transplant patient with recalcitrant groin lymphorrhoea was successfully treated with a combination of intraoperative lymphatic mapping and sartorius muscle flap. We believe that the combined use of these two treatment options offers a more effective approach for surgical treatment of recalcitrant groin lymphorrhoea and should be considered when managing this difficult clinical problem, especially in high-risk patients.

The A2a/A2b receptor antagonist ZM-241385 blocks the cardioprotective effect of adenosine agonist pretreatment in in vivo rat myocardium

There is increasing evidence for interactions among adenosine receptor subtypes in the brain and heart. The purpose of this study was to determine whether the adenosine A(2a) receptor modulates the infarct size-reducing effect of preischemic administration of adenosine receptor agonists in intact rat myocardium. Adult male rats were submitted to in vivo regional myocardial ischemia (25 min) and 2 h reperfusion. Vehicle-treated rats were compared with rats pretreated with the A(1) agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA, 10 mug/kg), the nonselective agonist 5'-N-ethylcarboxamidoadenosine (NECA, 10 mug/kg), or the A(2a) agonist 2-[4-(2-carboxyethyl)phenethylamino]-5'-N-methylcarboxamidoadenosine (CGS-21680, 20 mug/kg). Additional CCPA- and NECA-treated rats were pretreated with the A(1) antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 100 mug/kg), the A(2a)/A(2b) antagonist 4-(-2-[7-amino-2-{2-furyl}{1,2,4}triazolo{2,3-a} {1,3,5}triazin-5-yl-amino]ethyl)phenol (ZM-241385, 1.5 mg/kg) or the A(3) antagonist 3-propyl-6-ethyl-5[(ethylthio)carbonyl]-2-phenyl-4-propyl-3-pyridine carboxylate (MRS-1523, 2 mg/kg). CCPA and NECA reduced myocardial infarct size by 50% and 35%, respectively, versus vehicle, but CGS-21680 had no effect. DPCPX blunted the bradycardia associated with CCPA and NECA, whereas ZM-241385 attenuated their hypotensive effects. Both DPCPX and ZM-241385 blocked the protective effects of CCPA and NECA. The A(3) antagonist did not alter the hemodynamic effects of CCPA or NECA, nor did it alter adenosine agonist cardioprotection. None of the antagonists alone altered myocardial infarct size. These findings suggest that although preischemic administration of an A(2a) receptor agonist does not induce cardioprotection, antagonism of the A(2a) and/or the A(2b) receptor blocks the cardioprotection associated with adenosine agonist pretreatment.

National Surgical Quality Improvement Program (NSQIP) risk factors can be used to validate American Society of Anesthesiologists Physical Status Classification (ASA PS) levels

OBJECTIVE

The purpose of this study was to determine the relationship between the American Society of Anesthesiologists' Physical Status (ASA PS) classifications and the other National Surgical Quality Improvement Program (NSQIP) preoperative risk factors.

BACKGROUND

The ASA PS has been shown to predict morbidity and mortality in surgical patients but is inconsistently applied and clinically imprecise. It is desirable to have a method for validating ASA PS classification levels.

METHODS

The NSQIP preoperative risk factors, including ASA PS, were recorded from a random sample of 5878 surgical patients on 6 services between October 1, 2001 and September 30, 2003 at the University of Kentucky Medical Center. Mortality, morbidity, costs, and length of stay were obtained and compared across ASA PS levels. The ability of 1) ASA PS alone, 2) the other NSQIP risk factors, and, 3) all factors combined to predict outcomes was analyzed. A model using the other NSQIP risk factors was developed to predict ASA PS.

RESULTS

ASA PS alone was a strong predictor of outcomes (P < 0.01). However, the other NSQIP risk factors were better predictors as a group. There was significant interdependence between the ASA PS and the other NSQIP risk factors. Predictions of ASA PS using the other factors showed strong agreement with the anesthesiologists' assignments.

CONCLUSIONS

The NSQIP risk factors other than ASA PS can and should be used to validate ASA PS classifications.

Mycophenolate mofetil reduces intimal thickness by intravascular ultrasound after heart transplant: reanalysis of the multicenter trial

The mycophenolate mofetil (MMF) trial involved 650 heart transplant patients from 28 centers who received MMF or azathioprine (AZA), both in combination with cyclosporine and corticosteroids. Baseline and 1-year intravascular ultrasound (IVUS) were performed in 196 patients (102 MMF and 94 AZA) with no differences between groups in IVUS results analyzed by morphometric analysis (average of 10 evenly spaced sites, without matching sites between studies). Baseline to first-year IVUS data can also be analyzed by site-to-site analysis (matching sites between studies), which has been reported to be more clinically relevant. Therefore, we used site-to-site analysis to reanalyze the multicenter MMF IVUS data.

RESULTS

IVUS images were reviewed and interpretable in 190 patients (99 MMF and 91 AZA) from the multicenter randomized trial. The AZA group compared to the MMF group had a larger number of patients with first-year maximal intimal thickness (MIT)>or=0.3 mm (43% vs. 23%, p=0.005), a greater decrease in the mean lumen area (p=0.02) and a decrease in the mean vessel area (the area actually increased in the MMF group, p=0.03).

CONCLUSION

MMF-treated heart transplant patients compared to AZA-treated patients, both concurrently on cyclosporine and corticosteroids, in this study have significantly less progression of first-year intimal thickening.

What do faculty observe of medical students' clinical performance?

BACKGROUND

An earlier study of our faculty's evaluation of junior medical students indicated that performance ratings were unreliable and reflected 1 underlying dimension. Other researchers have obtained similar results.

PURPOSE

The purpose of this study was to identify which aspects of students' clinical performance faculty actually observe.

METHODS

We analyzed the responses of 9 faculty members to an open-ended questionnaire concerning which aspects of clinical performance attending faculty observe. We also reviewed and summarized the written comments of 331 faculty evaluations of third-year medical students.

RESULTS

Analysis of the questionnaires and evaluations indicated that faculty members gauge medical knowledge, professionalism, and clinical reasoning skills from direct interaction with students. History-taking and physical examination skills are inferred from the quality of verbal presentations. Faculty have little basis for evaluating other important aspects of clinical performance.

CONCLUSIONS

Faculty primarily observe medical students' cognitive skills and professionalism. Faculty have little basis for evaluating most other features of clinical performance.

Preoperative risk factors and surgical complexity are more predictive of costs than postoperative complications: a case study using the National Surgical Quality Improvement Program (NSQIP) database

OBJECTIVE

This single-center study tested the hypothesis that preoperative risk factors and surgical complexity predict more variation in hospital costs than complications.

BACKGROUND

Complications after surgical operations have been shown to significantly increase hospital cost. The impact on complication-related costs of preoperative risk factors is less well known.

METHODS

The National Surgical Quality Improvement Program (NSQIP) preoperative risk factors, surgical complexity, and outcomes, along with hospital costs, were analyzed for a random sample of 5875 patients on 6 surgical services. Operation complexity was assessed by work RVUs (Centers for Medicare and Medicaid Services Resource Based Relative Value Scale). The difference in mean hospital costs associated with all variables was analyzed. Multiple linear regression was used to determine the cost variation associated with all variables separately and combined.

RESULTS

Fifty-one of 60 preoperative risk factors, work RVUs, and 22 of 29 postoperative complications were associated with higher variable direct costs (P < 0.05). Linear regressions showed that risk factors predicted 33% (P < 0.001) of cost variation, work RVUs predicted 23% (P < 0.001), and complications predicted 20% (P < 0.001). Risk factors and work RVUs together predicted 49% of cost variation (P < 0.001) or 16% more than risk factors alone. Adding complications to this combined model modestly increased prediction of costs by 4% for a total of 53% (P < 0.001).

CONCLUSION

Preoperative risk factors and surgical complexity are more effective predictors of hospital costs than complications. Preoperative intervention to reduce risk could lead to significant cost savings. Payers and regulatory agencies should risk-adjust hospital cost assessments using clinical information that integrates costs, preoperative risk, complexity of operation, and outcomes.

Aged Rat Myocardium Exhibits Normal Adenosine Receptor-Mediated Bradycardia and Coronary Vasodilation But Increased Adenosine Agonist-Mediated Cardioprotection

The purpose of this study was to determine whether aged myocardium exhibits decreased responsiveness to adenosine A1 and A(2a) receptor activation. Studies were conducted in adult (4-6 months) and aged (24-26 months) Fischer 344 x Brown Norway hybrid (F344 x BN) rats. Effects of the adenosine A1/A(2a) agonist AMP579 were measured in isolated hearts and in rats submitted to in vivo regional myocardial ischemia. Aged isolated hearts exhibited lower spontaneous heart rates and higher coronary resistance, as well as normal A1- and A(2a)-mediated responses. There was no difference in control infarct size between adult and aged rats; however, AMP579 treatment resulted in a 50% greater infarct size reduction in aged rats (18 +/- 4% of risk area) compared to adult rats (37 +/- 3%). These findings suggest that adenosine A1 and A(2a) receptor-mediated effects are not diminished in normal aged myocardium, and that aged hearts exhibit increased adenosine agonist-induced infarct reduction.