The Infarct-Limiting Effect of Remote Ischemic Conditioning in Rats Is Not Affected by Aspirin.

PURPOSE: Remote ischemic conditioning (RIC) has been shown to be a powerful cardioprotective therapy in animal models. However, a protective effect in patients presenting with acute myocardial infarction has failed to be confirmed. A recent pre-clinical study reported that aspirin which is routinely given to patients undergoing reperfusion therapy blocked the infarct-limiting effect of ischemic postconditioning. The present study was designed to test whether aspirin could also be blocking the infarct-limiting effect of RIC. METHODS: This was investigated in vivo using male Sprague Dawley rats (n = 5 to 6 per group) subjected to either 30 min of regional myocardial ischemia, followed by 120-min reperfusion, or additionally to a RIC protocol initiated after 20-min myocardial ischemia. The RIC protocol included four cycles of 5-min hind limb ischemia interspersed with 5-min reperfusion. Intravenous aspirin (30 mg/kg) or vehicle (saline) was administered after 15-min myocardial ischemia. RESULTS: RIC significantly reduced infarct size (IS) normalized to the area at risk, by 47%. Aspirin administration did not affect IS nor did it attenuate the infarct-limiting effect of RIC. CONCLUSION: Aspirin administration in the setting of myocardial infarction is not likely to interfere with the cardioprotective effect of RIC.

Remote ischaemic conditioning: defining critical criteria for success-report from the 11th Hatter Cardiovascular Workshop.

The Hatter Cardiovascular Institute biennial workshop, originally scheduled for April 2020 but postponed for 2 years due to the Covid pandemic, was organised to debate and discuss the future of Remote Ischaemic Conditioning (RIC). This evolved from the large multicentre CONDI-2-ERIC-PPCI outcome study which demonstrated no additional benefit when using RIC in the setting of ST-elevation myocardial infarction (STEMI). The workshop discussed how conditioning has led to a significant and fundamental understanding of the mechanisms preventing cell death following ischaemia and reperfusion, and the key target cyto-protective pathways recruited by protective interventions, such as RIC. However, the obvious need to translate this protection to the clinical setting has not materialised largely due to the disconnect between preclinical and clinical studies. Discussion points included how to adapt preclinical animal studies to mirror the patient presenting with an acute myocardial infarction, as well as how to refine patient selection in clinical studies to account for co-morbidities and ongoing therapy. These latter scenarios can modify cytoprotective signalling and need to be taken into account to allow for a more robust outcome when powered appropriately. The workshop also discussed the potential for RIC in other disease settings including ischaemic stroke, cardio-oncology and COVID-19. The workshop, therefore, put forward specific classifications which could help identify so-called responders vs. non-responders in both the preclinical and clinical settings.

Targeting myocardial ischaemic injury in the absence of reperfusion.

Sudden myocardial ischaemia causes an acute coronary syndrome. In the case of ST-elevation myocardial infarction (STEMI), this is usually caused by the acute rupture of atherosclerotic plaque and obstruction of a coronary artery. Timely restoration of blood flow can reduce infarct size, but ischaemic regions of myocardium remain in up to two-thirds of patients due to microvascular obstruction (MVO). Experimentally, cardioprotective strategies can limit infarct size, but these are primarily intended to target reperfusion injury. Here, we address the question of whether it is possible to specifically prevent ischaemic injury, for example in models of chronic coronary artery occlusion. Two main types of intervention are identified: those that preserve ATP levels by reducing myocardial oxygen consumption, (e.g. hypothermia; cardiac unloading; a reduction in heart rate or contractility; or ischaemic preconditioning), and those that increase myocardial oxygen/blood supply (e.g. collateral vessel dilation). An important consideration in these studies is the method used to assess infarct size, which is not straightforward in the absence of reperfusion. After several hours, most of the ischaemic area is likely to become infarcted, unless it is supplied by pre-formed collateral vessels. Therefore, therapies that stimulate the formation of new collaterals can potentially limit injury during subsequent exposure to ischaemia. After a prolonged period of ischaemia, the heart undergoes a remodelling process. Interventions, such as those targeting inflammation, may prevent adverse remodelling. Finally, harnessing of the endogenous process of myocardial regeneration has the potential to restore cardiomyocytes lost during infarction.

Intrinsic cardiac ganglia and acetylcholine are important in the mechanism of ischaemic preconditioning.

This study aimed to investigate the role of the intrinsic cardiac nervous system in the mechanism of classical myocardial ischaemic preconditioning (IPC). Isolated perfused rat hearts were subjected to 35-min regional ischaemia and 60-min reperfusion. IPC was induced as three cycles of 5-min global ischaemia-reperfusion, and provided significant reduction in infarct size (IS/AAR = 14 ± 2% vs control IS/AAR = 48 ± 3%, p < 0.05). Treatment with the ganglionic antagonist, hexamethonium (50 µM), blocked IPC protection (IS/AAR = 37 ± 7%, p < 0.05 vs IPC). Moreover, the muscarinic antagonist, atropine (100 nM), also abrogated IPC-mediated protection (IS/AAR = 40 ± 3%, p < 0.05 vs IPC). This indicates that intrinsic cardiac ganglia remain intact in the Langendorff preparation and are important in the mechanism of IPC. In a second group of experiments, coronary effluent collected following IPC, from ex vivo perfused rat hearts, provided significant cardioprotection when perfused through a naïve isolated rat heart prior to induction of regional ischaemia-reperfusion injury (IRI) (IS/ARR = 19 ± 2, p < 0.05 vs control effluent). This protection was also abrogated by treating the naïve heart with hexamethonium, indicating the humoral trigger of IPC induces protection via an intrinsic neuronal mechanism (IS/AAR = 46 ± 5%, p < 0.05 vs IPC effluent). In addition, a large release in ACh was observed in coronary effluent was observed following IPC (IPCeff = 0.36 ± 0.03 µM vs C eff = 0.04 ± 0.04 µM, n = 4, p < 0.001). Interestingly, however, IPC effluent was not able to significantly protect isolated cardiomyocytes from simulated ischaemia-reperfusion injury (cell death = 45 ± 6%, p = 0.09 vs control effluent). In conclusion, IPC involves activation of the intrinsic cardiac nervous system, leading to release of ACh in the ventricles and induction of protection via activation of muscarinic receptors.

9th Hatter Biannual Meeting: position document on ischaemia/reperfusion injury, conditioning and the ten commandments of cardioprotection.

In the 30 years since the original description of ischaemic preconditioning, understanding of the pathophysiology of ischaemia/reperfusion injury and concepts of cardioprotection have been revolutionised. In the same period of time, management of patients with coronary artery disease has also been transformed: coronary artery and valve surgery are now deemed routine with generally excellent outcomes, and the management of acute coronary syndromes has seen decade on decade reductions in cardiovascular mortality. Nonetheless, despite these improvements, cardiovascular disease and ischaemic heart disease in particular, remain the leading cause of death and a significant cause of long-term morbidity (with a concomitant increase in the incidence of heart failure) worldwide. The need for effective cardioprotective strategies has never been so pressing. However, despite unequivocal evidence of the existence of ischaemia/reperfusion in animal models providing a robust rationale for study in man, recent phase 3 clinical trials studying a variety of cardioprotective strategies in cardiac surgery and acute ST-elevation myocardial infarction have provided mixed results. The investigators meeting at the Hatter Cardiovascular Institute workshop describe the challenge of translating strong pre-clinical data into effective clinical intervention strategies in patients in whom effective medical therapy is already altering the pathophysiology of ischaemia/reperfusion injury-and lay out a clearly defined framework for future basic and clinical research to improve the chances of successful translation of strong pre-clinical interventions in man.

The Saccharomyces SUN gene, UTH1, is involved in cell wall biogenesis.

Deletion of the Saccharomyces gene, UTH1, a founding member of the SUN family of fungal genes, has pleiotropic effects. Several phenotypes of Deltauth1 cells including their decreased levels of mitochondrial proteins, their impaired autophagic degradation of mitochondria, and their increased viability in the presence of mammalian BAX, a proapoptotic regulator localized to the mitochondria, have prompted others to propose that the Uth1p functions primarily at the mitochondria. In this report, we show that cells lacking UTH1 have more robust cell walls with higher levels of beta-d-glucan that allows them to grow in the presence of calcofluor white or sodium dodecyl sulfate, two reagents known to perturb the yeast cell wall. Moreover, these Deltauth1 cells are also significantly more resistant to spheroplast formation induced by zymolyase treatment than their wild-type counterparts. Surprisingly, our data suggest that several of the enhanced growth phenotypes of Deltauth1 cells, including their resistance to BAX-mediated toxicity, arise from a strengthened cell wall. Therefore, we propose that Uth1p's role at the cell wall and not at the mitochondria may better explain many of its effects on yeast physiology and programmed cell death.

Cigarette-smoking characteristics and interest in cessation in patients with head-and-neck cancer.

Purpose: Many patients diagnosed with head-and-neck cancer are current or former smokers. Despite the well-known adverse effects of smoking, continuation of smoking during cancer treatment is associated with reduced efficacy of that treatment and with cancer recurrence. In the present study, we examined smoking characteristics in patients with head-and-neck cancer near the time of cancer treatment. Methods: A prospective cohort of patients with head-and-neck cancer who attended a dental oncology clinic before receiving cancer treatment at a regional cancer centre were invited to participate in a study that involved completing an interviewer-administered questionnaire to assess smoking characteristics, intention to quit, motivation to quit, and strategies perceived to potentially aid in successful cessation. Results: The study enrolled 493 ever-smokers, with a response rate of 96.1% and a self-reported current smoker rate of 37.1% (n = 183). Most of the current smokers reported high nicotine dependence, with 84.7% (n = 155) indicating a time to first cigarette of 30 minutes or less. Most had previously attempted to quit smoking (77.0%), and many had prior unsuccessful quit attempts before resuming smoking again. Most were interested in quitting smoking (85.8%), and many (70.5%) were seriously considering quitting smoking within the subsequent 30 days. Conclusions: Patients with head-and-neck cancer reported high nicotine dependence and high interest in cessation opportunities near the time of treatment for cancer. Those results might provide support for provision of smoking cessation opportunities.

How can we better help cancer patients quit smoking? The London Regional Cancer Program experience with smoking cessation.

Background: Because continued cigarette smoking after a cancer diagnosis is associated with detrimental outcomes, supporting cancer patients with smoking cessation is imperative. We evaluated the effect of the Smoking Cessation Program at the London Regional Cancer Program (lrcp) over a 2-year period. Methods: The Smoking Cessation Program at the lrcp began in March 2014. New patients are screened for tobacco use. Tobacco users are counselled about the benefits of cessation and are offered referral to the program. If a patient accepts, a smoking cessation champion offers additional counselling. Follow-up is provided by interactive voice response (ivr) telephone system. Accrual data were collected monthly from January 2015 to December 2016 and were evaluated. Results: During 2015-2016, 10,341 patients were screened for tobacco use, and 18% identified themselves as current or recent tobacco users. In 2015, 84% of tobacco users were offered referral, but only 13% accepted, and 3% enrolled in ivr follow-up. At the lrcp in 2016, 77% of tobacco users were offered referral to the program, but only 9% of smokers accepted, and only 2% enrolled in ivr follow-up. Conclusions: The Smoking Cessation Program at the lrcp has had modest success, because multiple factors influence a patient's success with cessation. Limitations of the program include challenges in referral and counselling, limited access to nicotine replacement therapy (nrt), and minimal follow-up. To mitigate some of those challenges, a pilot project was launched in January 2017 in which patients receive free nrt and referral to the local health unit.

Leptin, the obesity-associated hormone, exhibits direct cardioprotective effects.

BACKGROUND AND PURPOSE: Protection against ischaemia-reperfusion (I/R) injury involves PI3K-Akt and p44/42 MAPK activation. Leptin which regulates appetite and energy balance also promotes myocyte proliferation via PI3K-Akt and p44/42 MAPK activation. We, therefore, hypothesized that leptin may also exhibit cardioprotective activity. EXPERIMENTAL APPROACH: The influence of leptin on I/R injury was examined in perfused hearts from C57Bl/6 J mice that underwent 35 min global ischaemia and 35 min reperfusion, infarct size being assessed by triphenyltetrazolium chloride staining. The concomitant activation of cell-signalling pathways was investigated by Western blotting. The effect of leptin on mitochondrial permeability transition pore (MPTP) opening was studied in rat cardiomyocytes. KEY RESULTS: Leptin (10 nM) administered during reperfusion reduced infarct size significantly. Protection was blocked by either LY294002 or UO126, inhibitors of Akt and p44/42 MAPK, respectively. Western blotting confirmed that leptin stimulated p44/42 MAPK phosphorylation significantly. Akt phosphorylation was also enhanced but did not achieve statistical significance. Additionally, leptin treatment was associated with a significant increase in p38 phosphorylation. By contrast, leptin caused downregulation of phosphorylated and non-phosphorylated STAT3, and of total AMP-activated kinase. Cardiomyocytes responded to leptin with delayed opening of the MPTP and delayed time until contracture. CONCLUSIONS AND IMPLICATIONS: Our data indicate for the first time that the adipocytokine, leptin, has direct cardioprotective properties which may involve the PI3-Akt and p44/42 MAPK pathways.

Association and release of prostaglandin E1 from liposomes.

PGE1-lipid interactions were studied in several liposome systems. Data from both circular dichroic (CD) measurements and differential scanning calorimetry (DSC) indicated that PGE1 in the protonated form seeks the less polar environment of the lipid bilayer. CD measurements made on PGE1 in solution showed that the wavelength of maximum absorbance red shifted approximately 8 nm with decreasing solvent polarity. The CD spectrum of liposomal PGE1 prepared in pH 4.5 but not pH 7.2 buffer was also red shifted. There was no red shift in the CD spectrum of PGE1 detected at pH 4.5 in the absence of phospholipid. DSC measurements on DSPC bilayers prepared with 5 mol% PGE1 at pH 4.5 but not pH 7.2 revealed an almost complete loss of the pre-transition as well as broadening of the main phase transition. The amount of 3H-PGE1 initially associated with EPC, POPC or DSPC liposomes was determined using size exclusion filters and centrifugation. This amount was found to be dependent on the pH of the buffer (pH 4.5 >> pH 7.2) and fluidity of the bilayer (EPC = POPC > DSPC), but independent of the lamellarity of the liposome. In all cases, addition of cholesterol reduced the amount of PGE1 associated with the liposome. The time-dependent release of PGE1 from the liposomes was determined by rapidly diluting the sample 100-fold into pH 7.2 buffer. Lipid saturation was a key factor influencing this release. Gel-phase liposomes of DSPC showed a rapid initial release (t(1/2) < 2 min) of PGE1, corresponding to the amount in the outer monolayer, followed by a very slow, almost negligible release of the remaining PGE1. A rapid initial release also occurred in fluid-phase membranes, followed by a more gradual release of the remaining PGE1 over several hours. This release rate could be slowed by increasing the lamellarity of these liposomes, or adding cholesterol to decrease the fluidity of the membrane.

Hypertension continuation adherence: natural history and role as an indicator condition.

We analyzed a random sample of general medicine clinic patients to determine the natural history of newly treated hypertensive (NH) patients: discontinuation patterns, critical intervention periods, and hypertension's (HBP) utility as an indicator condition. The NH patients exhibited a 48% dropout rate in the first year and better continuation adherence than new nonhypertensive (NNH) patients. Patients with HBP and other chronic diseases had better continuation adherence than those with HBP alone, although no predictive patterns emerged. New patients displayed rapid early discontinuation, with further linear decline by four months for NNH and by eight months for NH patients. All patients showed similar subsequent falloff: linear annual decline at 13% to 36%. We conclude that discontinuation rates are unacceptably high, that interventions must be continued throughout treatment, and that HBP has limited utility as an indicator chronic disease.

Full and limited medicaid participation among pediatricians.

Participation in Medicaid by pediatricians is an important element in the access of low income children to health care. Factors that influence whether participating pediatricians choose to participate fully in the program or to limit their acceptance of Medicaid patients are identified and analyzed. Data were derived from interviews conducted with 814 pediatricians in 13 states. A multivariate analysis examining physician, practice, service area, and Medicaid policy characteristics indicates that policy factors are most influential in the physician's decision whether to participate fully in medicaid programs. Factors found to foster the willingness of pediatricians to participate fully in state Medicaid programs included more competitive levels of reimbursement, minimal delays in reimbursement, and eligibility and benefit policies that minimize interference with the exercise of medical judgment.

Prepayment with office-based physicians in publicly funded programs: results from the Children's Medicaid Program.

This paper is a report of the results of a demonstration designed to provide empirical evidence regarding the effects of alternative approaches to paying physicians for serving children in the Medicaid program: (1) visit fees set at twice regular Medicaid fees in return for physician agreement to manage utilization and (2) capitation and financial risk-sharing along with the same physician agreement to manage utilization. Participating physicians were assigned randomly to either of the two payment groups. Comparisons of utilization and expenditures were made between these two plans and the regular Medicaid program (fee-for-service, low fees). Results showed no adverse effect of capitation payments on primary care visits to office-based physicians. Capitation physician referrals to specialists decreased relative to all other groups studied, consistent with the theory that the financial incentives in capitation will lead primary care physicians to reduce referrals to specialists.

The extent of physician participation in Medicaid: a comparison of physician estimates and aggregated patient records.

This article compares two measures of the extent of physician participation in Medicaid programs. The first, which has been used in most research to date on the subject, is based on physician estimates of the proportion of their patients who are Medicaid patients. The second derives from encounter forms for a sample of visits to the interviewed physicians. The comparison shows that physicians in the sample tended to overestimate by 40 percent the extent of their Medicaid participation. Because the two measures are highly correlated, the analysis of the determinants of Medicaid participation was not affected by the measure used. However, since physicians tended to overstate the proportion of Medicaid patients in their practices, interview data should not be used to measure the amount of physician participation or to calculate elasticities for the effects of policy changes on the extent of participation.

The Medical Care Advisory Committee for state Medicaid programs: current status and trends.

Each State Medicaid program is required by Federal Regulations to have a Medical Care Advisory Committee ( MCAC ) which includes provider, consumer, and government representatives and which participates in policy development and program administration. Data are presented about the composition of these committees, their structure, the administrative and financial support they receive, and the nature of their activities. It is argued that they can play an important role in policy formulation and implementation, but that they need to be reformed in order to exploit that potential.

Mitochondrial pharmacology: energy, injury and beyond.

While the mitochondrion has long fascinated biologists and the sheer diversity of druggable targets has made it attractive for potential drug development, there has been little success translatable to the clinic. Given the diversity of inborn errors of metabolism and mitochondrial diseases, mitochondrially mediated oxidative stress (myopathies, reperfusion injury, Parkinson's disease, ageing) and the consequences of disturbed energetics (circulatory shock, diabetes, cancer), the potential for meaningful gain with novel drugs targeting mitochondrial mechanisms is huge both in terms of patient quality of life and health care costs. In this themed issue of the British Journal of Pharmacology, we highlight the key directions of the contemporary advances in the field of mitochondrial biology, emerging drug targets and new molecules which are close to clinical application. Authors' contributions are diverse both in terms of species and organs in which the mitochondrially related studies are performed, and from the perspectives of mechanisms under study. Defined roles of mitochondria in disease are updated and previously unknown contributions to disease are described in terms of the interface between basic science and pathological relevance.

DJ-1 protects against cell death following acute cardiac ischemia-reperfusion injury.

Novel therapeutic targets are required to protect the heart against cell death from acute ischemia-reperfusion injury (IRI). Mutations in the DJ-1 (PARK7) gene in dopaminergic neurons induce mitochondrial dysfunction and a genetic form of Parkinson's disease. Genetic ablation of DJ-1 renders the brain more susceptible to cell death following ischemia-reperfusion in a model of stroke. Although DJ-1 is present in the heart, its role there is currently unclear. We sought to investigate whether mitochondrial DJ-1 may protect the heart against cell death from acute IRI by preventing mitochondrial dysfunction. Overexpression of DJ-1 in HL-1 cardiac cells conferred the following beneficial effects: reduced cell death following simulated IRI (30.4±4.7% with DJ-1 versus 52.9±4.7% in control; n=5, P<0.05); delayed mitochondrial permeability transition pore (MPTP) opening (a critical mediator of cell death) (260±33 s with DJ-1 versus 121±12 s in control; n=6, P<0.05); and induction of mitochondrial elongation (81.3±2.5% with DJ-1 versus 62.0±2.8% in control; n=6 cells, P<0.05). These beneficial effects of DJ-1 were absent in cells expressing the non-functional DJ-1(L166P) and DJ-1(Cys106A) mutants. Adult mice devoid of DJ-1 (KO) were found to be more susceptible to cell death from in vivo IRI with larger myocardial infarct sizes (50.9±3.5% DJ-1 KO versus 41.1±2.5% in DJ-1 WT; n≥7, P<0.05) and resistant to cardioprotection by ischemic preconditioning. DJ-1 KO hearts showed increased mitochondrial fragmentation on electron microscopy, although there were no differences in calcium-induced MPTP opening, mitochondrial respiratory function or myocardial ATP levels. We demonstrate that loss of DJ-1 protects the heart from acute IRI cell death by preventing mitochondrial dysfunction. We propose that DJ-1 may represent a novel therapeutic target for cardioprotection.