Mitochondrial MsrB2 serves as a switch and transducer for mitophagy.

Mitophagy can selectively remove damaged toxic mitochondria, protecting a cell from apoptosis. The molecular spatial-temporal mechanisms governing autophagosomal selection of reactive oxygen species (ROS)-damaged mitochondria, particularly in a platelet (no genomic DNA for transcriptional regulation), remain unclear. We now report that the mitochondrial matrix protein MsrB2 plays an important role in switching on mitophagy by reducing Parkin methionine oxidation (MetO), and transducing mitophagy through ubiquitination by Parkin and interacting with LC3. This biochemical signaling only occurs at damaged mitochondria where MsrB2 is released from the mitochondrial matrix. MsrB2 platelet-specific knockout and in vivo peptide inhibition of the MsrB2/LC3 interaction lead to reduced mitophagy and increased platelet apoptosis. Pathophysiological importance is highlighted in human subjects, where increased MsrB2 expression in diabetes mellitus leads to increased platelet mitophagy, and in platelets from Parkinson's disease patients, where reduced MsrB2 expression is associated with reduced mitophagy. Moreover, Parkin mutations at Met192 are associated with Parkinson's disease, highlighting the structural sensitivity at the Met192 position. Release of the enzyme MsrB2 from damaged mitochondria, initiating autophagosome formation, represents a novel regulatory mechanism for oxidative stress-induced mitophagy.

Antiplatelet therapy for tibial balloon angioplasty: A clinical perspective.

Percutaneous transluminal tibial balloon angioplasty has an important role in the therapeutic approach of critical limb ischaemia. Despite a growing number of patients with critical limb ischaemia, there are no trials to guide the pharmacologic approach post intervention. Guidelines pertaining to the antiplatelet therapy post percutaneous transluminal tibial balloon angioplasty have not been developed. In addition, critical limb ischaemia patients have multiple comorbidities and a higher risk of bleeding. To examine the shortest duration of antiplatelet therapy post percutaneous transluminal tibial balloon angioplasty, we reviewed the preclinical data used to develop the standards for the current angioplasty technique.

Age associated non-linear regulation of redox homeostasis in the anucleate platelet: Implications for CVD risk patients.

BACKGROUND: Aging is a complex physiological phenomenon, intricately associated with cardiovascular pathologies, where platelets play a central pathophysiological role. Although antiplatelets are commonly employed to prevent and treat major adverse cardiovascular events, aging associated intraplatelet changes remain largely unexplored. METHODS: Platelets were studied in high cardiovascular risk patients (aged 40-100 years) comparing them to younger healthy subjects. This was followed by cross sectional and longitudinal mice studies. Flow cytometry, biochemical and molecular assays were used to study platelets comprehensively. FINDINGS: CVD Patients were categorized in the age groups 40-59, 60-79, and 80-100 years. Progressive decline in platelet health was observed in the 40-79 years age cohort, marked by increase in oxidative stress, hyperactivation and apoptotic markers. Paradoxically, this was reversed in patients aged above 79 years and the improved platelet phenotype was associated with lower oxidative damage. The platelets from the very old (80-100 year) group were found to be preloaded with increased antioxidants, which also contributed to higher resistance against induced redox insults. Cross sectional mouse studies excluded the effect of comorbidities and medications. Longitudinal mouse studies implicate an adaptive increase in antioxidant levels as the mechanism. INTERPRETATION: We report a novel age associated, non-linear redox regulation in platelets in both humans and mice. In advanced age, there occurs an adaptive increase in platelet antioxidants, reducing the intracellular ROS and leading to a healthier platelet phenotype. Clinically, our results advocate the use of less aggressive antiplatelet therapies for CVD in the elderly population. FUND: Study funded by NIH-NHLBI, RO1-HL122815 and RO1-HL115247.

Review of the Current Basic Science Strategies to Treat Critical Limb Ischemia.

Critical limb ischemia (CLI) is a highly morbid disease with many patients considered poor surgical candidates. The lack of treatment options for CLI has driven interest in developing molecular therapies within recent years. Through these translational medicine studies in CLI, much has been learned about the pathophysiology of the disease. Here, we present an overview of the macrovascular and microvascular changes that lead to the development of CLI, including impairment of angiogenesis, vasculogenesis, and arteriogenesis. We summarize the randomized clinical controlled trials that have used molecular therapies in CLI, and discuss the novel imaging modalities being developed to assess the efficacy of these therapies.

Comorbidities frequency in Takotsubo syndrome: an international collaborative systematic review including 1109 patients.

BACKGROUND: To identify predisposing factors that can result in the onset of takotsubo syndrome, we performed an international, collaborative systematic review focusing on clinical characteristics and comorbidities of patients with takotsubo syndrome. METHODS: We searched and reviewed cited references up to August 2013 to identify relevant studies. Corresponding authors of selected studies were contacted and asked to provide additional quantitative details. Data from each study were extracted by 2 independent reviewers. The cumulative prevalence of presenting features and comorbidities was assessed. Nineteen studies whose authors sent the requested information were included in the systematic review, with a total of 1109 patients (951 women; mean age, 59-76 years). Evaluation of risk factors showed that obesity was present in 17% of patients (range, 2%-48%), hypertension in 54% (range, 27%-83%), dyslipidemia in 32% (range, 7%-59%), diabetes in 17% (range, 4%-34%), and smoking in 22% (range, 6%-49%). Emotional stressors preceded takotsubo syndrome in 39% of patients and physical stressors in 35%. The most common comorbidities were psychological disorders (24%; range, 0-49%), pulmonary diseases (15%; range, 0-22%), and malignancies (10%; range, 4%-29%). Other common associated disorders were neurologic diseases (7%; range, 0-22%), chronic kidney disease (7%; range, 2%-27%), and thyroid diseases (6%; range, 0-37%). CONCLUSIONS: Patients with takotsubo syndrome have a relevant prevalence of cardiovascular risk factors and associated comorbidities. Such of associations needs to be evaluated in further studies.

Prospective chest pain evaluation in the emergency department with use of high-sensitivity C-reactive protein (PROCEED-CRP study).

We evaluated the clinical value of a single measurement of high-sensitivity C-reactive protein (hs- CRP) in patients presenting to the emergency department with chest pain. We screened 408 consecutive patients of whom 292 comprised the final cohort for this study. Hs-CRP measured in the emergency department (ED) in patients presenting with chest pain and admitted for evaluation of acute myocardial infarction was neither sensitive nor specific in predicting acute myocardial infarction, myocardial ischemia on SPECT imaging, need for coronary revascularization, or cardiovascular or all-cause rehospitalization at 30 days. In addition, use of a specific CRP cut off >1 was not associated with an increase in all-cause rehospitalization at 30 days.

Treatment and outcomes of nonagenarians with ST-elevation myocardial infarction.

There is no age limit for reperfusion therapy in the current guidelines for the treatment of patients with ST-elevation myocardial infarction (STEMI). Reperfusion therapy, although associated with better outcomes, is not always offered to the oldest patients. A retrospective analysis at our institution of all patients ≥ 90 years of age with a diagnosis of acute coronary syndrome at discharge from 2004 to 2008 identified 24 patients with STEMI. The majority of patients were Caucasian, females, hypertensive, with a low incidence of dementia and diabetes. Only 29% of patients presented to the hospital in less than 6 hours. Thirteen patients were treated with percutaneous coronary intervention (PCI) and 11 patients were treated medically. The in-hospital mortality was 23% in the PCI group and 36% in the medical therapy group. Kaplan-Meier analysis demonstrated a survival benefit favoring PCI, which disappeared when only patients presenting after 6 hours to the hospital were analyzed. PCI-treated patients had no procedure-associated complications and had a good prognosis if they survived to hospital discharge. PCI should be offered to nonagenarians presenting with STEMI.

Long-term outcome of Tako-tsubo cardiomyopathy.

BACKGROUND: Current data suggest an excellent outcome for patients with Tako-tsubo cardiomyopathy (TC). The objectives of this study were to evaluate the long-term outcome and the prognostic implication of thrombolysis in myocardial infarction myocardial perfusion grade (TMPG) in patients with TC. METHODS: Retrospective analysis of all patients diagnosed with TC at our hospital between 2003 and 2008. RESULTS: During the five-year period, we identified 27 patients with TC out of 1374 cases of emergent left heart catheterisation (2%). Mean follow-up was 27 ± 16 months. The majority were Caucasian (81%) female (96%), postmenopausal (96%), with a mean age of 68 ± 14 years. A precipitating stressor event was found in 74% of the patients, 30% being gastrointestinal triggers. Fourteen patients (52%) reached a combined end point of all cause death, cardiogenic shock, sudden cardiac death and rehospitalisation for cardiac reasons. TMPG was abnormal in 37% cases with no correlation with the outcome. CONCLUSIONS: The long-term outcome of patients with TC is worse than previously reported. TMPG does not correlate with the outcome in TC.

A rare cause of systolic murmur: unruptured right sinus of Valsalva aneurysm with right ventricular outflow tract obstruction and supracristal ventricular septal defect.

Dyspnea and heart murmur are common reasons for referrals in cardiology and both are associated with a broad differential diagnosis. Sinus of Valsalva aneurysms are rare abnormalities of the aortic root that should be considered in the differential diagnosis in young and middle aged patients. Sinus of Valsalva aneurysms are often associated with supracristal ventricular septal defects and can be identified on transthoracic echocardiography. Diagnosis of a SVA should trigger a careful search for ventricular septal defect, which may necessitate transesophageal echocardiography.

Cardiac assessment of patients with Becker's muscular dystrophy.

Becker's muscular dystrophy (BMD) is one of the most common muscular dystrophy syndromes. The heart is always affected by myocardial fibrosis with early involvement of the right side. Traditionally, ECG, echocardiography and stress testing have been used to evaluate these patients. Cardiac MRI, offering superior assessment of the right side and visualization of the myocardial fibrosis could become the preferred imaging modality for evaluating patients with BMD.

ECG findings in acute left main coronary artery thrombosis: a case report and review of the literature.

Acute coronary syndrome due to left main coronary artery (LMCA) thrombosis is a catastrophic event associated with poor prognosis and high in-hospital mortality. Early recognition and emergent revascularization is vital for survival. Unfortunately, the electrocardiographic manifestations of LMCA thrombosis are nonspecific. This report describes the electrocardiogram (ECG) findings in a patient with LMCA thrombosis. A new right bundle branch block (RBBB) pattern, especially when associated with ST elevation in aVR and V1, should raise suspicion of this diagnosis.

The yeast rRNA biosynthesis factor Ebp2p is also required for efficient nuclear division.

Molecular genetic analysis of the yeast Ebp2 protein has revealed that it is an essential, nucleolar protein that functions in the rRNA biosynthesis pathway. Temperature-sensitive ebp2-1 mutants are defective in the processing of the 27 SA precursor rRNA, and the point substitutions that disrupt this activity cluster towards the central, more highly conserved region of the Ebp2 protein. We report here that other ebp2 mutants exhibit deficiencies associated with defects in chromosome segregation. Yeast cells bearing a 50 amino acid C-terminal truncation allele (ebp2 delta C50) display a slow-growth phenotype and exhibit an increased percentage of cells with the nucleus positioned at the bud neck. The ebp2-1 and ebp2 delta C50 alleles genetically complement each other, and ebp2 delta C50 mutants exhibit nuclear division defects that are distinct from the rRNA biosynthesis-related phenotypes of ebp2-1 mutants. Cytological and FACS analysis of the ebp2 delta C50 deletion mutants indicate that the chromosome segregation related activities of the Ebp2 protein are monitored by Mad2p, a mitotic checkpoint protein. The finding that yeast Ebp2p functions in nuclear division is consistent with the growing body of evidence that supports the role that human EBP2 plays in chromosome segregation.

Monomeric yeast PCNA mutants are defective in interacting with and stimulating the ATPase activity of RFC.

Yeast PCNA is a homo-trimeric, ring-shaped DNA polymerase accessory protein that can encircle duplex DNA. The integrity of this multimeric sliding DNA clamp is maintained through the protein-protein interactions at the interfaces of adjacent subunits. To investigate the importance of trimer stability for PCNA function, we introduced single amino acid substitutions at residues (A112T, S135F) that map to opposite ends of the monomeric protein. Recombinant wild-type and mutant PCNAs were purified from E. coli, and they were tested for their properties in vitro. Unlike the stable wild-type PCNA trimers, the mutant PCNA proteins behaved as monomers when diluted to low nanomolar concentrations. In contrast to what has been reported for a monomeric form of the beta clamp in E. coli, the monomeric PCNAs were compromised in their ability to interact with their associated clamp loader, replication factor C (RFC). Similarly, monomeric PCNAs were not effective in stimulating the ATPase activity of RFC. The mutant PCNAs were able to form mixed trimers with wild-type subunits, although these mixed trimers were unstable when loaded onto DNA. They were able to function as weak DNA polymerase delta processivity factors in vitro, and when the monomeric PCNA-41 (A112T, S135F double mutant) allele was introduced as the sole source of PCNA in vivo, the cells were viable and healthy. These pol30-41 mutants were, however, sensitive to UV irradiation and to the DNA damaging agent methylmethane sulfonate, implying that DNA repair pathways have a distinct requirement for stable DNA clamps.