Early remote ischaemic preconditioning leads to sustained improvement in allograft function after live donor kidney transplantation: long-term outcomes in the REnal Protection Against Ischaemia-Reperfusion in transplantation (REPAIR) randomised trial.

BACKGROUND: The REnal Protection Against Ischaemia-Reperfusion in transplantation (REPAIR) RCT examined whether remote ischaemic preconditioning (RIPC) improved renal function after living-donor kidney transplantation. The primary endpoint, glomerular filtration rate (GFR), quantified by iohexol at 12 months, suggested that RIPC may confer longer-term benefit. Here, we present yearly follow-up data of estimated GFR for up to 5 yr after transplantation. METHODS: In this double-blind, factorial RCT, we enrolled 406 adult live donor kidney transplant donor-recipient pairs in 15 European transplant centres. RIPC was performed before induction of anaesthesia. RIPC consisted of four 5 min inflations of a BP cuff on the upper arm to 40 mm Hg above systolic BP separated by 5 min periods of cuff deflation. For sham RIPC, cuff inflation to 40 mm Hg was undertaken. Pairs were randomised to sham RIPC, early RIPC only (immediately pre-surgery), late RIPC only (24 h pre-surgery), or dual RIPC (early and late RIPC). The pre-specified secondary outcome of estimated GFR (eGFR) was calculated from serum creatinine measurements, using the Chronic Kidney Disease Epidemiology Collaboration equation. Predefined safety outcomes were mortality and graft loss. RESULTS: There was a sustained improvement in eGFR after early RIPC, compared with control from 3 months to 5 yr (adjusted mean difference: 4.71 ml min-1 (1.73 m)-2 [95% confidence interval, CI: 1.54-7.89]; P=0.004). Mortality and graft loss were similar between groups (RIPC: 20/205 [9.8%] vs control 24/201 [11.9%]; hazard ratio: 0.79 [95% CI: 0.43-1.43]). CONCLUSIONS: RIPC safely improves long-term kidney function after living-donor renal transplantation when administered before induction of anaesthesia. CLINICAL TRIAL REGISTRATION: ISRCTN30083294.

Inhibition of phosphodiesterase 2 augments cGMP and cAMP signaling to ameliorate pulmonary hypertension.

BACKGROUND: Pulmonary hypertension (PH) is a life-threatening disorder characterized by increased pulmonary artery pressure, remodeling of the pulmonary vasculature, and right ventricular failure. Loss of endothelium-derived nitric oxide (NO) and prostacyclin contributes to PH pathogenesis, and current therapies are targeted to restore these pathways. Phosphodiesterases (PDEs) are a family of enzymes that break down cGMP and cAMP, which underpin the bioactivity of NO and prostacyclin. PDE5 inhibitors (eg, sildenafil) are licensed for PH, but a role for PDE2 in lung physiology and disease has yet to be established. Herein, we investigated whether PDE2 inhibition modulates pulmonary cyclic nucleotide signaling and ameliorates experimental PH. METHODS AND RESULTS: The selective PDE2 inhibitor BAY 60-7550 augmented atrial natriuretic peptide- and treprostinil-evoked pulmonary vascular relaxation in isolated arteries from chronically hypoxic rats. BAY 60-7550 prevented the onset of both hypoxia- and bleomycin-induced PH and produced a significantly greater reduction in disease severity when given in combination with a neutral endopeptidase inhibitor (enhances endogenous natriuretic peptides), trepostinil, inorganic nitrate (NO donor), or a PDE5 inhibitor. Proliferation of pulmonary artery smooth muscle cells from patients with pulmonary arterial hypertension was reduced by BAY 60-7550, an effect further enhanced in the presence of atrial natriuretic peptide, NO, and treprostinil. CONCLUSIONS: PDE2 inhibition elicits pulmonary dilation, prevents pulmonary vascular remodeling, and reduces the right ventricular hypertrophy characteristic of PH. This favorable pharmacodynamic profile is dependent on natriuretic peptide bioactivity and is additive with prostacyclin analogues, PDE5 inhibitor, and NO. PDE2 inhibition represents a viable, orally active therapy for PH.

Remote ischemic conditioning: from experimental observation to clinical application: report from the 8th Biennial Hatter Cardiovascular Institute Workshop.

In 1993, Przyklenk and colleagues made the intriguing experimental observation that 'brief ischemia in one vascular bed also protects remote, virgin myocardium from subsequent sustained coronary artery occlusion' and that this effect'... may be mediated by factor(s) activated, produced, or transported throughout the heart during brief ischemia/reperfusion'. This seminal study laid the foundation for the discovery of 'remote ischemic conditioning' (RIC), a phenomenon in which the heart is protected from the detrimental effects of acute ischemia/reperfusion injury (IRI), by applying cycles of brief ischemia and reperfusion to an organ or tissue remote from the heart. The concept of RIC quickly evolved to extend beyond the heart, encompassing inter-organ protection against acute IRI. The crucial discovery that the protective RIC stimulus could be applied non-invasively, by simply inflating and deflating a blood pressure cuff placed on the upper arm to induce cycles of brief ischemia and reperfusion, has facilitated the translation of RIC into the clinical setting. Despite intensive investigation over the last 20 years, the underlying mechanisms continue to elude researchers. In the 8th Biennial Hatter Cardiovascular Institute Workshop, recent developments in the field of RIC were discussed with a focus on new insights into the underlying mechanisms, the diversity of non-cardiac protection, new clinical applications, and large outcome studies. The scientific advances made in this field of research highlight the journey that RIC has made from being an intriguing experimental observation to a clinical application with patient benefit.

Clinical applications of remote ischaemic preconditioning in native and transplant acute kidney injury.

Ischaemia-reperfusion (IR) injury is a composite of the injury sustained during a period of reduced or absent blood flow to a tissue or organ and the additional insult sustained upon reperfusion that limits the amount of tissue that can be salvaged. IR injury plays a central role in both native and transplant acute kidney injury (AKI). Native AKI is associated with increased morbidity and mortality in hospital inpatients, and transplant AKI contributes to graft dysfunction, ultimately limiting graft longevity. In this review, we discuss the potential therapeutic benefits of a cost-effective and low-risk intervention, remote ischaemic preconditioning (RIPC), and its applicability in the prevention and reduction of AKI.

Dietary nitrate ameliorates pulmonary hypertension: cytoprotective role for endothelial nitric oxide synthase and xanthine oxidoreductase.

BACKGROUND: Pulmonary hypertension (PH) is a multifactorial disease characterized by increased pulmonary vascular resistance and right ventricular failure; morbidity and mortality remain unacceptably high. Loss of nitric oxide (NO) bioactivity is thought to contribute to the pathogenesis of PH, and agents that augment pulmonary NO signaling are clinically effective in the disease. Inorganic nitrate (NO(3)(-)) and nitrite (NO(2)(-)) elicit a reduction in systemic blood pressure in healthy individuals; this effect is underpinned by endogenous and sequential reduction to NO. Herein, we determined whether dietary nitrate and nitrite might be preferentially reduced to NO by the hypoxia associated with PH, and thereby offer a convenient, inexpensive method of supplementing NO functionality to reduce disease severity. METHODS AND RESULTS: Dietary nitrate reduced the right ventricular pressure and hypertrophy, and pulmonary vascular remodeling in wild-type mice exposed to 3 weeks of hypoxia; this beneficial activity was mirrored largely by dietary nitrite. The cytoprotective effects of dietary nitrate were associated with increased plasma and lung concentrations of nitrite and cGMP. The beneficial effects of dietary nitrate and nitrite were reduced in mice lacking endothelial NO synthase or treated with the xanthine oxidoreductase inhibitor allopurinol. CONCLUSIONS: These data demonstrate that dietary nitrate, and to a lesser extent dietary nitrite, elicit pulmonary dilatation, prevent pulmonary vascular remodeling, and reduce the right ventricular hypertrophy characteristic of PH. This favorable pharmacodynamic profile depends on endothelial NO synthase and xanthine oxidoreductase -catalyzed reduction of nitrite to NO. Exploitation of this mechanism (ie, dietary nitrate/nitrite supplementation) represents a viable, orally active therapy for PH.

Comparative efficacy and tolerability of anti-epileptic drugs for refractory focal epilepsy: systematic review and network meta-analysis reveals the need for long term comparator trials.

AIMS: To evaluate the comparative efficacy (50% reduction in seizure frequency) and tolerability (premature withdrawal due to adverse events) of anti-epileptic drugs (AEDs) for refractory epilepsy. METHODS: We searched Cochrane Central Register of Controlled Trials (Cochrane Library 2009, issue 2) including Epilepsy Group's specialized register, MEDLINE (1950 to March 2009), EMBASE (1980 to March 2009), and Current Contents Connect (1998 to March 2009) to conduct a systematic review of published studies, developed a treatment network and undertook a network meta-analysis. RESULTS: Forty-three eligible trials with 6346 patients and 12 interventions, including placebo, contributed to the analysis. Only three direct drug comparator trials were identified, the remaining 40 trials being placebo-controlled. Conventional random-effects meta-analysis indicated all drugs were superior in efficacy to placebo (overall odds ratio (OR] 3.78, 95% CI 3.14, 4.55) but did not permit firm distinction between drugs on the basis of the efficacy or tolerability. A Bayesian network meta-analysis prioritized oxcarbazepine, topiramate and pregabalin on the basis of short term efficacy. However, sodium valproate, levetiracetam, gabapentin and vigabatrin were prioritized on the basis of short-term efficacy and tolerability, with the caveat that vigabatrin is recognized as being associated with serious visual disturbance with chronic use. CONCLUSION: Of the wide range of AEDs licensed for the treatment of refractory epilepsy, sodium valproate, levetiracetam and gabapentin demonstrated the best balance of efficacy and tolerability. Until regulators mandate greater use of active comparator trials with longer term follow-up, network meta-analysis provides the only available means to quantify these clinically important parameters.

Vasoactive peptides and the pathogenesis of pulmonary hypertension: role and potential therapeutic application.

Pulmonary hypertension (PH) is a debilitating disease with a dismal prognosis. Recent advances in therapy (e.g. prostacyclin analogues, endothelin receptor antagonists and phosphodiesterase 5 inhibitors), whilst significantly improving survival, simply delay the inexorable progression of the disease. An array of endogenous vasoconstrictors and vasodilators coordinates to maintain pulmonary vascular homeostasis and morphological integrity, and an imbalance in the expression and function of these mediators precipitates PH and related lung diseases. The vasodilator peptides, including natriuretic peptides, vasoactive intestinal peptide, calcitonin gene-related peptide and adrenomedullin, trigger the production of cyclic nucleotides (e.g. cGMP and cAMP) in many pulmonary cell types, which in tandem exert a multifaceted protection against the pathogenesis of PH, encompassing vasodilatation, inhibition of vascular smooth muscle proliferation, anti-inflammatory and anti-fibrotic effects and salutary actions on the right ventricle. This coordinated beneficial activity underpins a contemporary perception that to advance treatment of PH it is necessary to offset multiple disease mechanisms (i.e. the pulmonary vasoconstriction, pulmonary vascular remodelling, right ventricular dysfunction). Thus, there is considerable potential for harnessing the favourable activity of peptide mediators to offer a novel, efficacious therapeutic approach in PH.

Remote ischemic preconditioning protects the brain against injury after hypothermic circulatory arrest.

BACKGROUND: Ischemic preconditioning (IPC) is a mechanism protecting tissues from injury during ischemia and reperfusion. Remote IPC (RIPC) can be elicited by applying brief periods of ischemia to tissues with ischemic tolerance, thus protecting vital organs more susceptible to ischemic damage. Using a porcine model, we determined whether RIPC of the limb is protective against brain injury caused by hypothermic circulatory arrest (HCA). METHODS AND RESULTS: Twelve piglets were randomized to control and RIPC groups. RIPC was induced in advance of cardiopulmonary bypass by 4 cycles of 5 minutes of ischemia of the hind limb. All animals underwent cardiopulmonary bypass followed by 60 minutes of HCA at 18°C. Brain metabolism and electroencephalographic activity were monitored for 8 hours after HCA. Assessment of neurological status was performed for a week postoperatively. Finally, brain tissue was harvested for histopathological analysis. Study groups were balanced for baseline and intraoperative parameters. Brain lactate concentration was significantly lower (P<0.0001, ANOVA) and recovery of electroencephalographic activity faster (P<0.05, ANOVA) in the RIPC group. RIPC had a beneficial effect on neurological function during the 7-day follow-up (behavioral score; P<0.0001 versus control, ANOVA). Histopathological analysis demonstrated a significant reduction in cerebral injury in RIPC animals (injury score; mean [interquartile range]: control 5.8 [3.8 to 7.5] versus RIPC 1.5 [0.5 to 2.5], P<0.001, t test). CONCLUSIONS: These data demonstrate that RIPC protects the brain against HCA-induced injury, resulting in accelerated recovery of neurological function. RIPC might be neuroprotective in patients undergoing surgery with HCA and improve long-term outcomes. Clinical trials to test this hypothesis are warranted.

Postconditioning protects against human endothelial ischaemia-reperfusion injury via subtype-specific KATP channel activation and is mimicked by inhibition of the mitochondrial permeability transition pore.

AIMS: Intermittent early reperfusion (ischaemic postconditioning; PostC) reduces ischaemia-reperfusion (IR) injury. Using an in vivo model of endothelial IR injury in humans, we sought to determine the role of K(ATP) channels in PostC and whether inhibition of the mitochondrial permeability transition pore (mPTP) at the onset of reperfusion protected against endothelial IR injury. METHODS AND RESULTS: Endothelial function (EF) in healthy volunteers was assessed using vascular ultrasound to measure the percentage increase in the diameter of the brachial artery in response to reactive hyperaemia [flow-mediated dilatation (FMD)]. In resistance vessels, venous occlusion plethysmography was used to measure the dilator response to acetylcholine (ACh) [area under ACh dose-response curve (ACh AUC)]. Measurements were made before and after IR injury. Ischaemic postconditioning consisted of three 10 s cycles of alternating ischaemia and reperfusion in the first minute of reperfusion. Oral glibenclamide and glimepiride were used to determine the role of K(ATP) channel subtypes in PostC. Intra-arterial cyclosporine was used to determine the role of mPTP in endothelial IR injury. Ischaemia-reperfusion reduced EF in the brachial artery (FMD 7.1 ± 0.9% pre-IR, 2.8 ± 0.4% post-IR; P < 0.001) and resistance vessels [ACh AUC (×10(4)) 2.1 ± 0.4 pre-IR, 1.5 ± 0.2 post-IR; P < 0.05]. Ischaemic postconditioning preserved EF in the brachial artery [FMD 6.8 ± 0.9% (P < 0.001 vs. post-IR)] and resistance vessels [ACh AUC (×10(4)) 1.9 ± 0.2 (P < 0.001 vs. post-IR)]. Protection by PostC was abolished by glibenclamide in the brachial artery [FMD 3.3 ± 0.2% (P < 0.001 vs. post-IR + PostC)] and in resistance vessels [ACh AUC (×10(4)) 1.1 ± 0.2 (P < 0.001 vs. post-IR + PostC)], whereas glimepiride had no effect. Cyclosporine preserved EF after IR injury in the resistance vessels [ACh AUC (×10(4)) 1.4 ± 0.2 post-IR vs. 2.2 ± 0.3 post-IR + cyclosporine; P < 0.05]. CONCLUSION: Protection by PostC against endothelial IR injury in humans depends on K(ATP) channel activation and is mimicked by inhibition of the mPTP at reperfusion.

Role of NADPH oxidase in endothelial ischemia/reperfusion injury in humans.

BACKGROUND: Reactive oxygen species have been implicated in the pathogenesis of ischemia/reperfusion (IR) injury. Recent studies suggest that NADPH oxidase may be a source of ROS during IR. Using an in vivo model of endothelial IR injury in the arm, we compared the response to IR in healthy volunteers with that in patients with chronic granulomatous disease. These patients have a molecular lesion in a subunit of NADPH oxidase that renders the enzyme inactive. METHODS AND RESULTS: Flow-mediated dilatation was used to assess endothelial function in patients with X-linked (NOX2) or autosomal (p47) chronic granulomatous disease. IR injury was induced by 20 minutes of upper limb ischemia followed by reperfusion. Flow-mediated dilatation was determined before IR and after 20 minutes of reperfusion. The response to IR in chronic granulomatous disease patients was compared with that in age- and sex-matched healthy control subjects. Flow-mediated dilatation was expressed as mean and compared statistically with mixed linear models. IR caused a significant reduction in flow-mediated dilatation in control subjects (-5.1%; 95% confidence interval, 6.3 to 3.%; P<0.001; n=11). IR had no effect on endothelial function in NOX2-chronic granulomatous disease patients (-0.9; 95% confidence interval, -2.1 to 0.3; P=0.12; n=11). Similarly, IR-induced reduction in flow-mediated dilatation was not observed in p47-chronic granulomatous disease patients (-1.5%; 95% confidence interval, -3.1 to 0.2; P=0.08; n=6) in contrast to healthy control subjects (-6.5%; 95% confidence interval, -8.2 to -4.9%; P<0.001; n=6). CONCLUSIONS: These data indicate, for the first time in humans in vivo, that reactive oxygen species produced by NADPH oxidase are determinants of endothelial function after IR injury in humans. These findings have implications for the design of strategies to limit clinical IR injury.

Inhaled tiotropium bromide and risk of stroke.

AIMS: A recent communication from the United States Food and Drug Administration highlighted a possible increased risk of stroke associated with use of the relatively new inhaled anticholinergic drug, tiotropium bromide. Using the United Kingdom General Practice Research Database, we set out to assess the risk of stroke in individuals exposed to inhaled tiotropium bromide and two other inhaled treatments for airways disease. METHODS: We used the self-controlled case-series that reduces confounding and minimizes the potential for biases in the quantification of risk estimates. RESULTS: Of 1043 people with a diagnosis of incident stroke who had had at least one prescription for tiotropium bromide, 980 satisfied inclusion criteria. The age-adjusted incidence rate ratio for all-cause stoke in individuals exposed to tiotropium bromide (n = 980), ipratropium bromide (n = 4181) and fluticasone propionate/salmeterol xinafoate (n = 1000) was 1.1 [95% confidence interval (CI) 0.9, 1.3], 0.8 (95% CI 0.7, 0.9) and 1.0 (95% CI 0.9, 1.2), respectively. CONCLUSIONS: We found no evidence of an increased risk of all-cause stroke for individuals exposed to commonly prescribed inhaled treatments for chronic obstructive pulmonary disease.

Synergy between natriuretic peptides and phosphodiesterase 5 inhibitors ameliorates pulmonary arterial hypertension.

RATIONALE: Phosphodiesterase 5 (PDE5) inhibitors (e.g., sildenafil) are selective pulmonary vasodilators in patients with pulmonary arterial hypertension. The mechanism(s) underlying this specificity remains unclear, but studies in genetically modified animals suggest it might be dependent on natriuretic peptide bioactivity. OBJECTIVES: We explored the interaction between PDE5 inhibitors and the natriuretic peptide system to elucidate the (patho)physiological relationship between these two cyclic GMP (cGMP)-regulating systems and potential of a combination therapy exploiting these cooperative pathways. METHODS: Pharmacological evaluation of vascular reactivity was conducted in rat isolated conduit and resistance vessels from the pulmonary and systemic circulation in vitro, and in anesthetized mice in vivo. Parallel studies were undertaken in an animal model of hypoxia-induced pulmonary hypertension (PH). MEASUREMENTS AND MAIN RESULTS: Sildenafil augments vasodilatation to nitric oxide (NO) in pulmonary and systemic conduit and resistance arteries, whereas identical vasorelaxant responses to atrial natriuretic peptide (ANP) are enhanced only in pulmonary vessels. This differential activity is mirrored in vivo where sildenafil increases the hypotensive actions of ANP in the pulmonary, but not systemic, vasculature. In hypoxia-induced PH, combination of sildenafil plus the neutral endopeptidase (NEP) inhibitor ecadotril (which increases endogenous natriuretic peptide levels) acts synergistically, in a cGMP-dependent manner, to reduce many indices of disease severity without significantly affecting systemic blood pressure. CONCLUSIONS: These data demonstrate that PDE5 is a key regulator of cGMP-mediated vasodilation by ANP in the pulmonary, but not systemic, vasculature, thereby explaining the pulmonary selectivity of PDE5 inhibitors. Exploitation of this mechanism (i.e., PDE5 and neutral endopeptidase inhibition) represents a novel, orally active combination therapy for pulmonary arterial hypertension.

Improving the odds of drug development success through human genomics: modelling study.

Lack of efficacy in the intended disease indication is the major cause of clinical phase drug development failure. Explanations could include the poor external validity of pre-clinical (cell, tissue, and animal) models of human disease and the high false discovery rate (FDR) in preclinical science. FDR is related to the proportion of true relationships available for discovery (γ), and the type 1 (false-positive) and type 2 (false negative) error rates of the experiments designed to uncover them. We estimated the FDR in preclinical science, its effect on drug development success rates, and improvements expected from use of human genomics rather than preclinical studies as the primary source of evidence for drug target identification. Calculations were based on a sample space defined by all human diseases - the 'disease-ome' - represented as columns; and all protein coding genes - 'the protein-coding genome'- represented as rows, producing a matrix of unique gene- (or protein-) disease pairings. We parameterised the space based on 10,000 diseases, 20,000 protein-coding genes, 100 causal genes per disease and 4000 genes encoding druggable targets, examining the effect of varying the parameters and a range of underlying assumptions, on the inferences drawn. We estimated γ, defined mathematical relationships between preclinical FDR and drug development success rates, and estimated improvements in success rates based on human genomics (rather than orthodox preclinical studies). Around one in every 200 protein-disease pairings was estimated to be causal (γ = 0.005) giving an FDR in preclinical research of 92.6%, which likely makes a major contribution to the reported drug development failure rate of 96%. Observed success rate was only slightly greater than expected for a random pick from the sample space. Values for γ back-calculated from reported preclinical and clinical drug development success rates were also close to the a priori estimates. Substituting genome wide (or druggable genome wide) association studies for preclinical studies as the major information source for drug target identification was estimated to reverse the probability of late stage failure because of the more stringent type 1 error rate employed and the ability to interrogate every potential druggable target in the same experiment. Genetic studies conducted at much larger scale, with greater resolution of disease end-points, e.g. by connecting genomics and electronic health record data within healthcare systems has the potential to produce radical improvement in drug development success rate.

Neprilysin inhibition for pulmonary arterial hypertension: a randomized, double-blind, placebo-controlled, proof-of-concept trial.

BACKGROUND AND PURPOSE: Pulmonary arterial hypertension (PAH) is an incurable, incapacitating disorder resulting from increased pulmonary vascular resistance, pulmonary arterial remodelling, and right ventricular failure. In preclinical models, the combination of a PDE5 inhibitor (PDE5i) with a neprilysin inhibitor augments natriuretic peptide bioactivity, promotes cGMP signalling, and reverses the structural and haemodynamic deficits that characterize PAH. Herein, we conducted a randomized, double-blind, placebo-controlled trial to assess the efficacy and safety of repurposing the neprilysin inhibitor, racecadotril, in PAH. EXPERIMENTAL APPROACH: Twenty-one PAH patients stable on PDE5i therapy were recruited. Acute haemodynamic and biochemical changes following a single dose of racecadotril or matching placebo were determined; this was followed by a 14-day safety and efficacy evaluation. The primary endpoint in both steps was the maximum change in circulating atrial natriuretic peptide (ANP) concentration (Δmax ), with secondary outcomes including pulmonary and systemic haemodynamics plus mechanistic biomarkers. KEY RESULTS: Acute administration of racecadotril (100 mg) resulted in a 79% increase in the plasma ANP concentration and a 106% increase in plasma cGMP levels, with a concomitant 14% fall in pulmonary vascular resistance. Racecadotril (100 mg; t.i.d.) treatment for 14 days resulted in a 19% rise in plasma ANP concentration. Neither acute nor chronic administration of racecadotril resulted in a significant drop in mean arterial BP or any serious adverse effects. CONCLUSIONS AND IMPLICATIONS: This Phase IIa evaluation provides proof-of-principle evidence that neprilysin inhibitors may have therapeutic utility in PAH and warrants a larger scale prospective trial.

Transient limb ischemia induces remote preconditioning and remote postconditioning in humans by a K(ATP)-channel dependent mechanism.

BACKGROUND: Transient limb ischemia administered before a prolonged ischemic insult has systemic protective effects against ischemia-reperfusion (IR) injury (remote ischemic preconditioning [RIPC]). It has been demonstrated that protection from IR can be achieved by brief periods of ischemia applied at a remote site during an injurious ischemic event (remote postconditioning [RPostC]). Using an in vivo model of endothelial IR injury, we sought to determine whether RPostC occurred in humans and whether it shared mechanistic similarities with RIPC. METHODS AND RESULTS: Endothelial function was assessed by flow-mediated dilation before and after IR (20 minutes of arm ischemia followed by reperfusion). RIPC was induced by conditioning cycles of 5 minutes of ischemia and reperfusion on the contralateral arm or leg before IR. For RPostC induction, conditioning cycles were administered during the ischemic phase of IR. Oral glibenclamide was used to determine the dependence of RIPC and RPostC on K(ATP) channels. IR caused a significant reduction in flow-mediated dilation in healthy volunteers (baseline, 9.3+/-1.2% versus post-IR, 3.3+/-0.7%; P<0.0001) and patients with atherosclerosis (baseline, 5.5+/-0.6% versus post-IR, 2.3+/-0.5%; P<0.01). This reduction was prevented by RIPC (post-IR+RIPC: healthy volunteers, 7.2+/-0.5% [P<0.0001 versus post-IR]; patients, 4.5+/-0.3% [P<0.01 versus post-IR]) and RPostC (post-IR+RPostC: 8.0+/-0.5%; P<0.0001 versus post-IR). The protective effects of RIPC and RPostC were blocked by glibenclamide. CONCLUSIONS: This study demonstrates for the first time in humans that RPostC can be induced by transient limb ischemia and is as effective as RIPC in preventing endothelial IR injury. RIPC and RPostC share mechanistic similarities, with protection being dependent on K(ATP) channel activation. These results suggest that remote conditioning stimuli could be protective in patients with acute ischemia about to undergo therapeutic reperfusion.

Effect of remote ischaemic preconditioning on myocardial injury in patients undergoing coronary artery bypass graft surgery: a randomised controlled trial.

BACKGROUND: Whether remote ischaemic preconditioning, an intervention in which brief ischaemia of one tissue or organ protects remote organs from a sustained episode of ischaemia, is beneficial for patients undergoing coronary artery bypass graft surgery is unknown. We did a single-blinded randomised controlled study to establish whether remote ischaemic preconditioning reduces myocardial injury in these patients. METHODS: 57 adult patients undergoing elective coronary artery bypass graft surgery were randomly assigned to either a remote ischaemic preconditioning group (n=27) or to a control group (n=30) after induction of anaesthesia. Remote ischaemic preconditioning consisted of three 5-min cycles of right upper limb ischaemia, induced by an automated cuff-inflator placed on the upper arm and inflated to 200 mm Hg, with an intervening 5 min of reperfusion during which the cuff was deflated. Serum troponin-T concentration was measured before surgery and at 6, 12, 24, 48, and 72 h after surgery. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00397163. FINDINGS: Remote ischaemic preconditioning significantly reduced overall serum troponin-T release at 6, 12, 24, and 48 h after surgery. The total area under the curve was reduced by 43%, from 36.12 microg/L (SD 26.08) in the control group to 20.58 microg/L (9.58) in the remote ischaemic preconditioning group (mean difference 15.55 [SD 5.32]; 95% CI 4.88-26.21; p=0.005). INTERPRETATION: We have shown that adult patients undergoing elective coronary artery bypass graft surgery at a single tertiary centre could benefit from remote ischaemic preconditioning, using transient upper limb ischaemia.

Post-marketing assessment of the safety of strontium ranelate; a novel case-only approach to the early detection of adverse drug reactions.

AIMS: Post licensing, the evaluation of drug safety relies heavily on the collation of sporadic, spontaneous reports on adverse effects. The aim was to assess the potential utility of a more systematic approach to the detection of adverse events that utilizes routinely collected clinical data from a large primary care population. METHODS: We used the UK General Practice Research Database to assess the risk of several recently reported adverse events linked to the use of strontium ranelate for osteoporosis in postmenopausal women. The self-controlled case-series method was used to minimize the potential for biases in the quantification of risk estimates. RESULTS: Age-adjusted rate ratios for venous thromboembolism, gastrointestinal disturbance, minor skin complaint and memory loss were 1.1 [95% confidence interval (CI) 0.2, 5.0], 3.0 (95% CI 2.3, 3.8), 2.0 (95% CI 1.3, 3.1) and 1.8 (95% CI 0.2, 14.1), respectively. No cases of osteonecrosis of the jaw, toxic-epidermal necrosis, Stevens-Johnson syndrome or drug rash with eosinophilia and systemic symptoms were found. CONCLUSIONS: Although we confirmed the association between strontium ranelate and adverse events identified in the Phase III publications, there was no evidence of an association between strontium ranelate and the aforementioned potentially life-threatening adverse events. Our study demonstrates the relative ease with which this method can assess a variety of adverse events associated with a new drug in actual clinical practice. We believe this technique could be more widely adopted to assess the safety profile of new drugs.

(6R)-5,6,7,8-tetrahydro-L-biopterin and its stereoisomer prevent ischemia reperfusion injury in human forearm.

OBJECTIVE: 6R-5,6,7,8-tetrahydro-L-biopterin (6R-BH4) is a cofactor for endothelial nitric oxide synthase but also has antioxidant properties. Its stereo-isomer 6S-5,6,7,8-tetrahydro-L-biopterin (6S-BH4) and structurally similar pterin 6R,S-5,6,7,8-tetrahydro-D-neopterin (NH4) are also antioxidants but have no cofactor function. When endothelial nitric oxide synthase is 6R-BH4-deplete, it synthesizes superoxide rather than nitric oxide. Reduced nitric oxide bioavailability by interaction with reactive oxygen species is implicated in endothelial dysfunction (ED). 6R-BH4 corrects ED in animal models of ischemia reperfusion injury (IRI) and in patients with cardiovascular risks. It is uncertain whether the effect of exogenous 6R-BH4 on ED is through its cofactor or antioxidant action. METHODS AND RESULTS: In healthy volunteers, forearm blood flow was measured by venous occlusion plethysmography during intra-arterial infusion of the endothelium-dependent vasodilator acetylcholine, or the endothelium-independent vasodilator glyceryl trinitrate, before and after IRI. IRI reduced plasma total antioxidant status (P=0.03) and impaired vasodilatation to acetylcholine (P=0.01), but not to glyceryl trinitrate (P=0.3). Intra-arterial infusion of 6R-BH4, 6S-BH4 and NH4 at approximately equimolar concentrations prevented IRI. CONCLUSION: IRI causes ED associated with increased oxidative stress that is prevented by 6R-BH4, 6S-BH4, and NH4, an effect mediated perhaps by an antioxidant rather than cofactor function. Regardless of mechanism, 6R-BH4, 6S-BH4, or NH4 may reduce tissue injury during clinical IRI syndromes.

Potent Anti-Inflammatory and Pro-Resolving Effects of Anabasum in a Human Model of Self-Resolving Acute Inflammation.

Anabasum is a synthetic analog of Δ8 -tetrahydrocannabinol (THC)-11-oic acid that in preclinical models of experimental inflammation exerts potent anti-inflammatory actions with minimal central nervous system (CNS) cannabimimetic activity. Here we used a novel model of acute inflammation driven by i.d. UV-killed E. coli in healthy humans and found that anabasum (5 mg) exerted a potent anti-inflammatory effect equivalent to that of prednisolone in terms of inhibiting neutrophil infiltration, the hallmark of acute inflammation. These effects arose from the inhibition of the neutrophil chemoattractant LTB4 , while the inhibition of antiphagocytic prostanoids (PGE2 , TxB2 , and PGF2 α) resulted in enhanced clearance of inflammatory stimulus from the injected site. Anabasum at the higher dose of 20 mg possessed the additional properties of triggering the biosynthesis of specialized pro-resolving lipid mediators including LXA4 , LXB4 , RvD1, and RvD3. Collectively, we demonstrate for the first time a striking anti-inflammatory and pro-resolution effects of a synthetic analog of THC in healthy humans.

Postconditioning protects against endothelial ischemia-reperfusion injury in the human forearm.

BACKGROUND: Hypoxic cell death follows interruption of blood supply to tissues. Although successful restoration of blood flow is mandatory for salvage of ischemic tissues, reperfusion can paradoxically place tissues at risk of further injury. Brief periods of ischemia applied at the onset of reperfusion have been shown to reduce ischemia-reperfusion (IR) injury, a phenomenon called postconditioning. The aim of this study was to determine whether postconditioning protects against endothelial IR injury in humans, in vivo. METHODS AND RESULTS: Brachial artery endothelial function was assessed by vascular ultrasound to measure flow-mediated dilation (FMD) in response to forearm reactive hyperemia. FMD was measured before and after IR (20 minutes of arm ischemia followed by 20 minutes of reperfusion) in healthy volunteers. To test the protective effects of postconditioning, 3 cycles of reperfusion followed by ischemia (each lasting 10 or 30 seconds) were applied immediately after 20 minutes of arm ischemia. To determine whether postconditioning needs to be applied at the onset of reperfusion, a 1-minute period of arm reperfusion was allowed before the application of the 10-second postconditioning stimulus. IR caused endothelial dysfunction (FMD 9.1+/-1.2% pre-IR, 3.6+/-0.7% post-IR, P<0.001; n=11), which was prevented by postconditioning applied as 10-second cycles of reperfusion/ischemia (FMD 9.9+/-1.7% pre-IR, 8.3+/-1.4% post-IR, P=NS; n=11) and 30-second cycles of reperfusion/ischemia (FMD 10.8+/-1.7% pre-IR, 9.5+/-1.5% post-IR, P=NS; n=10) immediately at the onset of reperfusion. No protection was observed when the application of the 10-second postconditioning stimulus was delayed for 1 minute after the onset of reperfusion (FMD 9.8+/-1.2% pre-IR, 4.0+/-0.9% post-IR, P<0.001; n=8). CONCLUSIONS: This study demonstrates for the first time that postconditioning can protect against endothelial IR injury in humans. Postconditioning might reduce tissue injury when applied at the onset of reperfusion by modifying the reperfusion phase of IR.