Effects of inosine on reperfusion injury after cardiopulmonary bypass

Objective: Inosine, a break-down product of adenosine has been recently shown to exert inodilatory and anti-inflammatory properties. Furthermore inosine might be a key substrate of pharmacological post-conditioning. In the present pre-clinical study, we investigated the effects of inosine on cardiac function during reperfusion in an experimental model of cardioplegic arrest and extracorporal circulation. Methods: Twelve anesthetized dogs underwent hypothermic cardiopulmonary bypass. After 60 minutes of hypothermic cardiac arrest, reperfusion was started after application of either saline vehicle (control, n = 6), or inosine (100 mg/kg, n = 6). Left ventricular end-systolic pressure volume relationship (ESPVR) was measured by a combined pressure-volume-conductance catheter at baseline and after 60 minutes of reperfusion. Left anterior descendent coronary blood flow (CBF), endothelium-dependent vasodilatation to acetylcholine (ACh) and endothelium-independent vasodilatation to sodium nitroprusside (SNP) were also determined. Results: The administration of inosine led to a significantly better recovery (given as percent of baseline) of ESPVR 90 ± 9% vs. 46 ± 6%, p &lt; 0.05. CBF and was also significantly higher in the inosine group (56 ± 8 vs. 23 ± 4, ml/min, p < 0.05). While the vasodilatatory response to SNP was similar in both groups, ACh resulted in a significantly higher increase in CBF (58 ± 6% vs. 25 ± 5%, p < 0.05) in the inosine group. Conclusions: Application of inosine improves myocardial and endothelial function after cardiopulmonary bypass with hypothermic cardiac arrest

Identification of Pharmacological Modulators of HMGB1-Induced Inflammatory Response by Cell-Based Screening

High mobility group box 1 (HMGB1), a highly conserved, ubiquitous protein, is released into the circulation during sterile inflammation (e.g. arthritis, trauma) and circulatory shock. It participates in the pathogenesis of delayed inflammatory responses and organ dysfunction. While several molecules have been identified that modulate the release of HMGB1, less attention has been paid to identify pharmacological inhibitors of the downstream inflammatory processes elicited by HMGB1 (C23-C45 disulfide C106 thiol form). In the current study, a cell-based medium-throughput screening of a 5000+ compound focused library of clinical drugs and drug-like compounds was performed in murine RAW264.7 macrophages, in order to identify modulators of HMGB1-induced tumor-necrosis factor alpha (TNFα) production. Clinically used drugs that suppressed HMGB1-induced TNFα production included glucocorticoids, beta agonists, and the anti-HIV compound indinavir. A re-screen of the NIH clinical compound library identified beta-agonists and various intracellular cAMP enhancers as compounds that potentiate the inhibitory effect of glucocorticoids on HMGB1-induced TNFα production. The molecular pathways involved in this synergistic anti-inflammatory effect are related, at least in part, to inhibition of TNFα mRNA synthesis via a synergistic suppression of ERK/IκB activation. Inhibition of TNFα production by prednisolone+salbutamol pretreatment was also confirmed in vivo in mice subjected to HMGB1 injection; this effect was more pronounced than the effect of either of the agents administered separately. The current study unveils several drug-like modulators of HMGB1-mediated inflammatory responses and offers pharmacological directions for the therapeutic suppression of inflammatory responses in HMGB1-dependent diseases. © 2013 Gerö et al

H2S biosynthesis and catabolism: new insights from molecular studies

Hydrogen sulfide (H2S) has profound biological effects within living organisms and is now increasingly being considered alongside other gaseous signalling molecules, such as nitric oxide (NO) and carbon monoxide (CO). Conventional use of pharmacological and molecular approaches has spawned a rapidly growing research field that has identified H2S as playing a functional role in cell-signalling and post-translational modifications. Recently, a number of laboratories have reported the use of siRNA methodologies and genetic mouse models to mimic the loss of function of genes involved in the biosynthesis and degradation of H2S within tissues. Studies utilising these systems are revealing new insights into the biology of H2S within the cardiovascular system, inflammatory disease, and in cell signalling. In light of this work, the current review will describe recent advances in H2S research made possible by the use of molecular approaches and genetic mouse models with perturbed capacities to generate or detoxify physiological levels of H2S gas within tissue

Cell proliferation and apoptosis in stromal corneal dystrophies

The aim of our study was to evaluate corneal cell proliferation and apoptosis in cases of granular, macular and lattice dystrophy, and to provide evidence which may help to clarify whether apoptosis is a pathogenic factor in any of these dystrophies. The study group comprised 39 eyes (from 33 patients) which had undergone penetrating keratoplasty (PK) for stromal dystrophies: these comprised 12 eyes (from 9 patients, 55.5% males) with granular dystrophy, 13 eyes (12 patients, 33.3% males) with macular dystrophy, and 14 eyes (13 patients, 61.5% males) with lattice type I dystrophy. A further 4 corneal buttons from enucleated eyes of 4 patients with choroideal melanoma served as controls. Immunocytochemical analysis of Ki67 (DNAcon Kit, DakoCytomation A/S, Glostrup, Denmark) was used for evaluation of cell proliferation. Apoptosis was detected by use of the TUNEL (terminal deoxyribonucleotidyl transferase-mediated dUTPdigoxigenin nick-end labelling) assay method (Apoptag reagent, Q-Biogene, Strasbourg, France). Statistical comparisons were made using the Mann-Whitney test. No Ki67-positive cells were detected in the studygroup or control corneas. In control corneas no apoptotic activity was found. In the study group the mean (normalised) apoptotic keratocyte number was 1.1±1.7 in granular dystrophy and 0.5±1.1 in lattice type I The aim of our study was to evaluate corneal cell proliferation and apoptosis in cases of granular, macular and lattice dystrophy, and to provide evidence which may help to clarify whether apoptosis is a pathogenic factor in any of these dystrophies. The study group comprised 39 eyes (from 33 patients) which had undergone penetrating keratoplasty (PK) for stromal dystrophies: these comprised 12 eyes (from 9 patients, 55.5% males) with granular dystrophy, 13 eyes (12 patients, 33.3% males) with macular dystrophy, and 14 eyes (13 patients, 61.5% males) with lattice type I dystrophy. A further 4 corneal buttons from enucleated eyes of 4 patients with choroideal melanoma served as controls. Immunocytochemical analysis of Ki67 (DNAcon Kit, DakoCytomation A/S, Glostrup, Denmark) was used for evaluation of cell proliferation. Apoptosis was detected by use of the TUNEL (terminal deoxyribonucleotidyl transferase-mediated dUTPdigoxigenin nick-end labelling) assay method (Apoptag reagent, Q-Biogene, Strasbourg, France). Statistical comparisons were made using the Mann-Whitney test. No Ki67-positive cells were detected in the studygroup or control corneas. In control corneas no apoptotic activity was found. In the study group the mean (normalised) apoptotic keratocyte number was 1.1±1.7 in granular dystrophy and 0.5±1.1 in lattice type I controls, the difference was statistically significant only for macular dystrophy (1.6±1.2; p = 0.01). Keratocyte apoptosis seems to be a concomitant or pathogenic factor in macular dystrophy. However, the pathways that are triggered to result in increased apoptotic cell death remain to be clarified