Siamak Davani

Mesenchymal Progenitor Cells Differentiate into an Endothelial Phenotype, Enhance Vascular Density, and Improve Heart Function in a Rat Cellular Cardiomyoplasty Model

Background—Cellular cardiomyoplasty is a promising approach to improve postinfarcted cardiac function. The differentiation pathways of engrafted mesenchymal progenitor cells (MPCs) and their effects on the left ventricular function in a rat myocardial infarct heart model were analyzed. Methods and Results—A ligation model of left coronary artery of Lewis rats was used. MPCs were isolated by bone marrow cell adherence. Seven days after ligation, MPCs labeled with 4′,6-diamidino-2′-phenylindole were injected into the infarcted myocardium (n=8). Culture medium was injected in the infarcted myocardium of control animals (n=8). Thirty days after implantation, immunofluorescence studies revealed some engrafted cells expressing a smooth muscle phenotype (&agr; SM actin+), as similarly observed in culture. Other engrafted cells lost their smooth muscle phenotype and acquired an endothelial phenotype (CD31+). Furthermore, vessel density was augmented in the MPC group in comparison with the control group. After 30 days, echocardiography showed an improvement on left ventricular performance in the MPCs compared with the control group. Conclusions—In vivo administration of syngenic MPCs into a rat model of myocardial infarcted heart was safety demonstrated. Some engrafted cells appeared to differentiate into endothelial cells and loss their smooth muscle phenotype. MPC engraftment might to contribute to the improvement on the cardiac function in such a setting.

Interindividual Variability of Methadone Response Impact of Genetic Polymorphism

Methadone, an opioid analgesic, is used clinically in pain therapy as well as for substitution therapy in opioid addiction. It has a large interindividual variability in response and a narrow therapeutic index. Genetic polymorphisms in genes coding for methadone-metabolizing enzymes, transporter proteins (p-glycoprotein; P-gp), and μ-opioid receptors may explain part of the observed interindividual variation in the pharmacokinetics and pharmacodynamics of methadone. Cytochrome P450 (CYP) 3A4 and 2B6 have been identified as the main CYP isoforms involved in methadone metabolism. Methadone is a P-gp substrate, and, although there are inconsistent reports, ABCB1 genetic polymorphisms also contribute slightly to the interindividual variability of methadone kinetics and influence dose requirements. Genetic polymorphism is the cause of high interindividual variability of methadone blood concentrations for a given dose; for example, in order to obtain methadone plasma concentrations of 250 ng/mL, doses of racemic methadone as low as 55 mg/day or as high as 921 mg/day can be required in a 70-kg patient without any co-medication.The clinician must be aware of the pharmacokinetic properties and pharmacological interactions of methadone in order to personalize methadone administration. In the future, pharmacogenetics, at a limited level, can also be expected to facilitate individualized methadone therapy.

Role of β1- and β2-adrenoceptor Subtypes in Preconditioning Against Myocardial Dysfunction after Ischemia and Reperfusion

Abstract:Using an isolated nonworking rat heart model, this study investigated the role of β-adrenergic preconditioning (β-PC) to attenuate myocardial dysfunction after an ischemia/reperfusion injury. After a 20-min stabilization period, the noradrenaline depleted hearts were perfused for 5 min with

Long-term prognostic value of residual pulmonary vascular obstruction at discharge in patients with intermediate- to high-risk pulmonary embolism

BACKGROUND We evaluated prognostic value at 6 months of residual pulmonary vascular obstruction (RPVO) measured before discharge in patients with intermediate- or high-risk pulmonary embolism (PE). METHODS AND RESULTS Prospective registry including 416 consecutive patients with intermediate- or high-risk PE who survived the acute phase. Patients with previous cardiopulmonary disease were excluded. Perfusion lung scans were performed within 6-8 days after the onset of treatment. Residual pulmonary vascular obstruction was graded as the proportion of the lung not perfused. Primary objective was a combined endpoint at 6 months, including death, recurrent PE, and appearance of signs of heart failure. At 6 months, 32 patients (7.7%) had at least one adverse event: 12 deaths (2.9%), 12 recurrent PE (2.9%), and 14 (3.4%) heart failure. Independent predictors of combined endpoint were: cancer [odds ratio (OR) 3.07 (1.22-7.85)]; renal insufficiency at admission [OR: 2.53 (1.17-5.8)]; persistent signs of right ventricular dysfunction at 48 h echography [OR: 3.99 (1.36-11.3)]. The severity of RPVO at discharge was significantly associated with an unfavourable outcome [OR: 2.66 (1.58-3.93)]. The incremental prognostic value of RPVO information was confirmed by significantly improved goodness-of-fit. Threshold RPVO for predicting adverse events was estimated at 35% [area under the curve = 0.76 (0.73-0.82)]. Patients with RPVO greater than threshold at discharge had a significantly higher risk of death at 6 months (P = 0.01). CONCLUSIONS Residual pulmonary vascular obstruction evaluated before hospital discharge in patients with intermediate- to high-risk PE is a powerful prognostic factor for a 6-month outcome. RPVO ≥35% is associated with an increased risk of adverse events at 6 months.

A neutropenia suggesting an interaction between valacyclovir and mycophenolate mofetil

Mycophenolate mofetil (MMF) is a drug which decreases the frequency of renal transplantation rejection. However, cytomegalovirus infections are a common feature of this treatment leading the physicians to prescribe antiviral prophylactic drugs like valacyclovir. During this association, neutropenia occur and the cause of this adverse effect is difficult to define. This report presents a case of neutropenia in a woman treated with MMF and valacyclovir. As the duration of the valacyclovir treatment exactly corresponds to the neutropenia duration, and the mycophenolate trough levels increased with the neutrophil count, the responsibility of this neutropenia was ascribed to valacyclovir. However, an examination of the literature for cases of neutropenia led to the suspicion of an interaction between MMF and valacyclovir. Mycophenolate may increase intracellular concentrations of valacyclovir up to haematotoxic levels. This mechanism may explain the interaction and further research is needed to confirm this interaction.

Presence of circulating endothelial progenitor cells and levels of stromal-derived factor-1α are associated with ascending aorta aneurysm size

OBJECTIVE Circulating endothelial progenitor cells (EPCs) are a specialized subset of stem/progenitor cells found in bone marrow. They participate in neo-vascularization of injured vessels and predict cardiovascular outcome in patient at risk. Several factors influence their migration and proliferation, among which is the widely studied stromal-derived factor-1α (SDF-1α). In cardiovascular disease, regarding thoracic aortic aneurysms (TAAs), few studies have investigated the levels of EPC and SDF-1α. As rupture, acute dissection and hematoma are acute complications of idiopathic ascending thoracic aortic aneurysm (iATAA) that increase with the size of aneurysm, we aimed to evaluate a potential relationship between circulating EPC and SDF-1α and iATAA size. METHODS The aneurysm size of 27 consecutive patients suffering from iATAA and scheduled for surgery was assessed by computed tomography scan. In all patients, we measured levels of circulating EPCs by flow cytometer, and plasma levels of SDF-1α the day before surgery. RESULTS The median aneurysm size was 54 mm (interquartile range (IQR): 50.0-58.8]. The EPC levels of CD34+/CD144+/CD14- and CD34+/VEGF-R2+/CD14- were inversely correlated to aneurysm diameter (p = 0.038, r = -0.424 and p = 0.0046, r = -0.65, respectively) before surgery. Conversely, plasma levels of SDF-1α were positively correlated to aneurysm size (p = 0.042; r = 0.47). CONCLUSIONS Our findings indicate that EPC levels may be useful for monitoring ascending aorta aneurysms and that SDF-1α could be a biomarker of iATAA expansion.

Neutrophil Gelatinase-Associated Lipocalin as Early Predictor of Acute Kidney Injury After Cardiac Surgery in Adults With Chronic Kidney Failure

BACKGROUND To assess the utility of neutrophil gelatinase-associated lipocalin (NGAL) as an early marker of acute kidney injury (AKI) occurring after cardiac surgery in patients with prior chronic kidney failure. METHODS Patients with preoperative creatinine clearance 60 mL • min(-1) • 1.73 m(-2) or less according to the Cockcroft-Gault formula and scheduled to undergo cardiac surgery were eligible for inclusion. The AKI was defined as an increase in plasma creatinine greater than 50% over preoperative values. Threshold values of NGAL predictive of AKI were determined using receiver operating characteristic curve analysis, and predictive value of NGAL for AKI was evaluated by logistic regression. RESULTS Over a 1-year inclusion period, 166 patients were included. At 6 hours post-surgery, hypertension, occurrence of at least 1 postoperative complication, and NGAL greater than 155 ng/mL were shown to be independent predictors of AKI. NGAL greater than 155 ng/mL at 6 hours was associated with an odds ratio for risk of postoperative AKI of 7.1 [2.7 to 18]. On average, diagnosis of postoperative AKI was made 20 hours earlier using NGAL at 6 hours post-surgery as compared with a diagnosis based on a 50% increase in creatinine over baseline. The threshold for NGAL of 155 ng/mL at 6 hours had a sensitivity of 79% and specificity of 58% for the diagnosis of AKI. CONCLUSIONS Earlier diagnosis of AKI post-surgery based on NGAL assessment makes it possible to initiate appropriate therapy at an earlier stage in this high-risk patient population.

Acitretin-Associated Thrombotic Stroke:

OBJECTIVE: To report a case of thrombotic stroke. The etiology was difficult to identify, but was finally ascribed to psoriatic treatment with acitretin. CASE SUMMARY: Treatment with acitretin was prescribed for a 52-year-old white woman for long-standing psoriasis. Thirty-four days later, she developed nausea, vomiting, vertigo, and headaches, followed by left lateropulsion, which impeded standing and lying. Both neurologic examination and magnetic nuclear imaging indicated a rectangular infarct in the vermis cerebelli and a small bulbar infarct. Time-of-flight magnetic resonance angiography confirmed the presence of a thrombus at the beginning of the left vertebral artery. After heparin-based treatment and physiotherapy, the evolution was favorable. DISCUSSION: Etiology identification of the stroke included cardiogenic pathology and coagulopathy, but acitretin treatment was considered the likeliest explanation. On review of the literature, this seems to be the first case of a thrombotic event associated with acitretin. CONCLUSIONS: Acitretin should be considered as a possible cause of thrombotic stroke; this possibility should be kept in mind when patients taking acitretin develop an unexplained thrombotic event.

Comparative lipidomics and proteomics analysis of platelet lipid rafts using different detergents

Abstract Lipid rafts play a pivotal role in physiological functions of platelets. Their isolation using nonionic mild detergents is considered as the gold standard method, but there is no consensual detergent for lipid raft studies. We aimed to investigate which detergent is the most suitable for lipid raft isolation from platelet membrane, based on lipidomics and proteomics analysis. Platelets were obtained from healthy donors. Twelve sucrose fractions were extracted by three different detergents, namely Brij 35, Lubrol WX, and Triton X100, at 0.05% and 1%. After lipidomics analysis and determination of fractions enriched in cholesterol (Ch) and sphingomyelin (SM), proteomics analysis was performed. Lipid rafts were mainly observed in 1–4 fractions, and non-rafts were distributed on 5–12 fractions. Considering the concentration of Ch and SM, Lubrol WX 1% and Triton X100 1% were more suitable detergents as they were able to isolate lipid raft fractions that were more enriched than non-raft fractions. By proteomics analysis, overall, 822 proteins were identified in platelet membrane. Lipid raft fractions isolated with Lubrol WX 0.05% and Triton X100 1% contained mainly plasma membrane proteins. However, only Lubrol WX 0.05 and 1% and Triton X100 1% were able to extract non-denaturing proteins with more than 10 transmembrane domains. Our results suggest that Triton X100 1% is the most suitable detergent for global lipid and protein studies on platelet plasma membrane. However, the detergent should be adapted if investigation of an association between specific proteins and lipid rafts is planned.

Effects of l-arginine administration before cardioplegic arrest on ischemia-reperfusion injury

BACKGROUND Administration of L-arginine during reperfusion or its addition to cardioplegic solution has been shown to protect myocardium against ischemia-reperfusion injury. This study aimed at evaluating the role of L-arginine in ischemia-reperfusion injury when administered intraperitoneally 24 hours before cardioplegic arrest. METHODS Two groups of Sprague-Dawley rats (control, n = 10; and L-arginine, n = 10) were studied in an isolated buffer-perfused heart model. Both groups were injected intraperitoneally 24 hours before ischemia. Before experimentation blood samples were collected for cardiac troponin I and cGMP analysis. In the coronary effluents, cardiac troponin I, adenosine, cyclic guanosine monophosphate, and nitric oxide metabolites were assayed. RESULTS Before heart excision, serum cardiac troponin I concentrations were higher in the L-arginine than in the control group (0.037 +/- 0.01 versus 0.02 +/- 0.05 microg x L(-1); p < 0.05). During reperfusion, cardiac troponin I release was lower in the L-arginine than in the control group (0.04 +/- 0.01 versus 0.19 +/- 0.03 ng x min(-1); p < 0.05). The coronary flow as well as the left ventricular developed pressure were higher in the L-arginine than in the control group before ischemia and remained so throughout the experimentation. CONCLUSIONS These results indicate that L-arginine administered intraperitoneally 24 hours before cardioplegic arrest reduced myocardial cell injury and seems to protect myocardium against ischemia-reperfusion injury.