Pankaj Saxena

Remote ischemic preconditioning decreases adhesion and selectively modifies functional responses of human neutrophils.

OBJECTIVES Preconditioning of cells or organs by transient sublethal ischemia-reperfusion (IR), termed ischemic preconditioning (IPC), protects the cell or organ from a subsequent prolonged ischemic insult. The mechanisms of this effect remain to be fully elucidated. We have recently reported that IPC of a forearm results in alterations in gene expression profiles of circulating polymorphonuclear leukocytes. The goal of the current study was to determine if the observed changes in gene expression lead to functional changes in neutrophils. METHODS We examined the effect of repetitive transient human forearm ischemia (three cycles of 5 min ischemia, followed by 5 min of reperfusion) on the function of circulating neutrophils. Neutrophil functions were examined before, after 1 d, and after 10 d of daily transient forearm ischemia. To modulate IR-induced inflammation the neutrophils were stimulated with N-formyl-methionyl-leucyl phenylalanine (FMLP) and lipopolysaccharide (LPS). RESULTS Neutrophil adhesion was significantly decreased on day 1 and remained low on day 10 (P = 0.0149) without significant change in CD11b expression. Phagocytosis was significantly suppressed on day 10 compared with day 0 (P < 0.0001). Extracellular cytokine levels were low in the absence of an exogenous stimulus but stimulation with LPS induced significant changes on day 10. We observed a trend in reduction of apoptosis on day 1 and day 10 that did not reach statistical significance (P < 0.08). CONCLUSION This study indicates that repetitive IPC of the forearm results in substantial alterations in neutrophil function, including reduced adhesion, exocytosis, phagocytosis, and modified cytokine secretion.

Remote Ischemic Conditioning: Evolution of the Concept, Mechanisms, and Clinical Application

Abstract  Remote ischemic conditioning is a novel concept of protection against ischemia‐reperfusion injury. Brief controlled episodes of intermittent ischemia of the arm or leg may confer a powerful systemic protection against prolonged ischemia in a distant organ. This conditioning phenomenon is clinically applicable and can be performed before—preconditioning, during—perconditioning, or after—postconditioning prolonged distant organ ischemia. The remote ischemic conditioning may have an immense impact on clinical practice in the near future. (J Card Surg 2010;25:127‐134)

Type-2 diabetes increases autophagy in the human heart through promotion of Beclin-1 mediated pathway

BACKGROUND Diabetes promotes progressive loss of cardiac cells, which are replaced by a fibrotic matrix, resulting in the loss of cardiac function. In the current study we sought to identify if excessive autophagy plays a major role in inducing this progressive loss. METHODS AND RESULTS Immunofluorescence and western blotting analysis of the right atrial appendages collected from diabetic and non-diabetic patients undergoing coronary artery bypass graft surgery showed a marked increase in the level of autophagy in the diabetic heart, as evidenced by increased expression of autophagy marker LC3B-II and its mediator Beclin-1 and decreased expression of p62, which incorporates into autophagosomes to be efficiently degraded. Moreover, a marked activation of pro-apoptotic caspase-3 was observed. Electron microscopy showed increased autophagosomes in the diabetic heart. In vivo measurement of autophagic flux by choloroquine injection resulted in further enhancement of LC3B-II in the diabetic myocardium, confirming increased autophagic activity in the type-2 diabetic heart. Importantly, in-vitro genetic depletion of beclin-1 in high glucose treated adult rat cardiomyocytes markedly inhibited the level of autophagy and subsequent apoptotic cell death. CONCLUSIONS These findings demonstrate the pathological role of autophagy in the type-2 diabetic heart, opening up a potentially novel therapeutic avenue for the treatment of diabetic heart disease.

The role of remote ischemic preconditioning in organ protection after cardiac surgery: a meta-analysis

BACKGROUND Remote ischemic preconditioning (RIPC) appears to protect distant organs from ischemia-reperfusion injury. We undertook meta-analysis of clinical studies to evaluate the effects of RIPC on organ protection and clinical outcomes in patients undergoing cardiac surgery. METHODS A review of evidence for cardiac, renal, and pulmonary protection after RIPC was performed. We also did meta-regressions on RIPC variables, such as duration of ischemia, cuff pressure, and timing of application of preconditioning. Secondary outcomes included length of hospital and intensive care unit stay, duration of mechanical ventilation, and mortality at 30 days. RESULTS Randomized control trials (n = 25) were included in the study for quantitative analysis of cardiac (n = 16), renal (n = 6), and pulmonary (n = 3) protection. RIPC provided statistically significant cardiac protection (standardized mean difference [SMD], -0.77; 95% confidence interval [CI], -1.15, -0.39; Z = 3.98; P < 0.0001) and on subgroup analysis, the protective effect remained consistent for all types of cardiac surgical procedures. However, there was no evidence of renal protection (SMD, 0.74; 95% CI, 0.53, 1.02; Z = 1.81; P = 0.07) or pulmonary protection (SMD, -0.03; 95% CI, -0.56, 0.50; Z = 0.12; P = 0.91). There was no statistical difference in the short-term clinical outcomes between the RIPC and control groups. CONCLUSIONS RIPC provides cardiac protection, but there is no evidence of renal or pulmonary protection in patients undergoing cardiac surgery using cardiopulmonary bypass. Larger multicenter trials are required to define the role of RIPC in surgical practice.

Rapid onset of cardiomyopathy in STZ-induced female diabetic mice involves the downregulation of pro-survival Pim-1

BackgroundDiabetic women are five times more likely to develop congestive heart failure compared with two fold for men. The underlying mechanism for this gender difference is not known. Here we investigate the molecular mechanisms responsible for this female disadvantage and attempt safeguarding cardiomyocytes viability and function through restoration of pro-survival Pim-1.Methods and ResultsDiabetes was induced by injection of streptozotocin in CD1 mice of both genders. Functional and dimensional parameters measurement using echocardiography revealed diastolic dysfunction in female diabetic mice within 8 weeks after STZ-induced diabetes. This was associated with significant downregulation of pro-survival Pim-1 and upregulation of pro-apoptotic Caspase-3, microRNA-1 and microRNA-208a. Male diabetic mice did not show any significant changes at this time point (P < 0.05 vs. female diabetic). Further, the onset of ventricular remodelling was quicker in female diabetic mice showing marked left ventricular dilation, reduced ejection fraction and poor contractility (P < 0.05 vs. male diabetic at 12 and 16 weeks of STZ-induced diabetes). Molecular analysis of samples from human diabetic hearts confirmed the results of pre-clinical studies, showing marked downregulation of Pim-1 in the female diabetic heart (P < 0.05 vs. male diabetic). Finally, in vitro restoration of Pim-1 reversed the female disadvantage in diabetic cardiomyocytes.ConclusionsWe provide novel insights into the molecular mechanisms behind the rapid onset of cardiomyopathy in female diabetics. These results suggest the requirement for the development of gender-specific treatments for diabetic cardiomyopathy.

Role of physiological lung exclusion in difficult lung resections for massive hemoptysis and other problems

OBJECTIVES Pulmonary tuberculosis and bronchiectasis are the major causes of massive hemoptysis in developing countries. Lung resection remains the surgical treatment of choice. This may not always be possible and may even be hazardous in some patients due to fibrosis and dense vascular adhesions between the lung and the chest wall. This leads to marked blood loss and control of hilar vessels becomes dangerous. METHODS A series of 20 cases is described here. Nineteen presented with massive hemoptysis where control of bleeding was obtained by physiological lung exclusion. One patient had traumatic left main bronchus transection not suitable for repair or resection. Physiological lung exclusion was performed by surgical interruption of the bronchus and pulmonary artery of the involved lobe or lung, keeping pulmonary veins intact. RESULTS Hemoptysis could be controlled in all these patients without any significant morbidity. There was no mortality. There was no postoperative empyema and recurrence of hemoptysis on long-term follow-up. No patient required anatomical lung resection later on. CONCLUSIONS Physiological lung exclusion is a safe and effective method for control of massive hemoptysis in cases where lung resection is technically hazardous or difficult. This should be kept as an alternative or adjunct to anatomical lung resection.

Surgical Repair of Cor Triatriatum Sinister: The Mayo Clinic 50-Year Experience

BACKGROUND Cor triatriatum is a rare congenital cardiac defect in which the atrium is divided into 2 chambers by a membrane causing obstruction to the blood flow in either the left atrium (cor triatriatum sinister) or the right atrium (cor triatriatum dexter) eventually leading to cardiac failure. We sought to review our surgical experience with cor triatriatum sinister. METHODS Twenty-five patients underwent surgical correction of cor triatriatum between May 1960 and September 2012. There were 11 males and 14 females with a mean age of 27.4 years (age range, 1 day to 73 years). RESULTS All patients underwent excision of cor triatriatum membrane using cardiopulmonary bypass. Twenty patients (80%) required concomitant cardiac surgical procedures. There was no early mortality. None of the patients had any residual atrial obstruction. Two infants who had concomitant repair of complex congenital anomalies died at 2 and 5 months postoperatively after discharge from hospital. Kaplan-Meier survival at 10 years was 83%. All patients were in New York Heart Association class I or II at a mean follow-up of 12.8 years (maximum 44 years). CONCLUSIONS Surgical repair of cor triatriatum provides satisfactory early and long-term survival with low risk for additional intervention. Cor triatriatum with complex congenital anomalies may be associated with adverse outcome.

Remote ischemic preconditioning stimulus decreases the expression of kinin receptors in human neutrophils

BACKGROUND Remote ischemic preconditioning (RIPC) has been shown to reduce ischemic-reperfusion injury and is induced by brief forearm ischemia. Kinins are known to be involved in RIPC and act via the G protein coupled B1 and B2 receptors. Interaction of the kinins with their respective receptors causes receptor internalization, thereby reducing the potential for further activation. This may be critical for the protective effect of RIPC and if so, we hypothesized, would significantly decrease the expression of kinin receptors on the surface of neutrophils. METHODS The study was performed on five healthy human volunteers. The left forearm was rendered ischemic for three 5-min periods, each separated by 5 min of reperfusion. Three venous blood samples were taken from the right arm, one before and two after RIPC. Neutrophil isolation, immunofluorescence labeling, and confocal microscopy were performed. Mean pixel intensity data were generated using a fixed circular area of interest (AOI, 40×40 μm). For every image, the AOI was placed over a cell and the mean pixel intensity was recorded. The mean intensity was expressed as pixel×10(2)/μm(2) and presented as mean±SEM. Immunofluorescence at the different time points was compared by one way analysis of variance with Bonferronis post-hoc test. A P value<0.05 was considered significant. RESULTS The mean pixel intensity for kinin B1 receptors was decreased at 24 h after RIPC compared with both baseline and 15 min after RIPC (P<0.001). Similarly, the intensity for B2 receptor labeling on neutrophils was significantly decreased 24 h after RIPC compared with the baseline value (P<0.001). CONCLUSIONS RIPC decreases expression of kinin receptors on circulating human neutrophils. Reduction in kinin surface receptors suggests internalization of receptors and is consistent with the concepts of kinin receptor activation and their role in RIPC.

Remote ischaemic preconditioning down-regulates kinin receptor expression in neutrophils of patients undergoing heart surgery

OBJECTIVES Remote ischaemic preconditioning (RIPC) may protect distant organs against ischaemia-reperfusion injury. We investigated the impact of RIPC on kinin receptor expression in neutrophils following RIPC in patients undergoing coronary artery bypass grafting (CABG). METHODS Patients undergoing elective CABG with cardiopulmonary bypass (CPB) were randomized to RIPC (n = 15) or control (n = 15) groups. The study group underwent RIPC by inflation of a blood pressure cuff on the arm. Expression of kinin receptors, plasma concentrations of IL-6, IL-8, IL-10, TNF-α and neutrophil elastase were determined at baseline (before RIPC/sham), immediately before surgery (after RIPC/sham) and 30 min and 24 h after surgery. Plasma bradykinin levels were assessed before and after RIPC/sham, and at 30 min, 6, 12 and 24 h after surgery. Serum creatine kinase (CK), troponin I, C-reactive protein (CRP) and lactate levels were measured immediately prior to surgery and 30 min, 6, 12, 24 and 48 h after surgery. RESULTS Kinin B2 receptor expression did not differ between the groups at baseline (pre-RIPC), but was significantly lower in the RIPC group than in the control group after RIPC/sham (P < 0.05). Expressions of both kinin B1 and B2 receptors were significantly down-regulated in the RIPC group, and this persisted to 24 h after surgery (P < 0.001). Neutrophil elastase levels were significantly increased after surgery. There were no differences in CK, CRP, cytokine, lactate or troponin I levels between the groups. CONCLUSIONS RIPC down-regulated the expression of kinin B1 and B2 receptors in neutrophils of patients undergoing CABG.

Extracorporeal Membrane Oxygenation Support in Postcardiotomy Elderly Patients: The Mayo Clinic Experience

BACKGROUND We conducted a retrospective study to assess whether providing extracorporeal membrane oxygenation (ECMO) support to elderly patients (aged 70 years or more) who failed separation from cardiopulmonary bypass after cardiac surgery was a viable option. METHODS From 2003 to 2013, 45 patients aged 70 years or more underwent 47 runs of ECMO postoperatively. RESULTS There were 31 men (68.9%). The mean age was 76.8 years. Five patients were in cardiogenic shock preoperatively. Forty-four patients required venoarterial ECMO support for cardiogenic shock. Mean duration of support was 103.8 ± 74.3 hours. Twenty-one patients (46.6%) died while on ECMO support. Twenty-four patients (53.3%) were weaned off ECMO initially, and 11 patients were discharged from hospital. Inhospital mortality was 75.6%. Postoperative complications included acute kidney injury in 30 patients (44.4%), pneumonia in 12 (26.7%), and sepsis in 11 (24.4%). There were 30 deaths (88.2%) attributable to cardiac causes. Preoperative atrial fibrillation, chronic kidney injury, lactic acidosis on ECMO support, and persistent coagulopathy were associated with higher mortality. CONCLUSIONS Postcardiotomy ECMO support in elderly patients is associated with high postoperative morbidity and mortality. Nevertheless, it often provides the last line of therapy for these critically ill patients and may provide positive outcomes in selected subgroups.