Evaluation of the ESMO-Magnitude of Clinical Benefit Scale version 1.1 (ESMO-MCBS v1.1) for adjuvant radiotherapy in breast cancer.

BACKGROUND: The European Society of Medical Oncology (ESMO) has suggested using the ESMO-Magnitude of Clinical Benefit Scale (MCBS) to grade the magnitude of clinical benefit of cancer therapies. This approach has not been applied to radiation therapy (RT) yet. We applied the ESMO-MCBS to experiences describing the use of RT to assess (1) the 'scoreability' of the data, (2) evaluate the reasonableness of the grades for clinical benefit and (3) identify potential shortcomings in the current version of the ESMO-MCBS in its applicability to RT. MATERIALS AND METHODS: We applied the ESMO-MCBS v1.1 to a selection of studies in radiotherapy that had been identified as references in the development of American Society for Radiation Oncology (ASTRO) evidence-based guidelines on whole breast radiation. Of the 112 cited references, we identified a subset of 16 studies that are amenable to grading using the ESMO-MCBS. RESULTS: Of the 16 studies reviewed, 3/16 were scoreable with the ESMO tool. Six of 16 studies could not be scored because of shortcomings in the ESMO-MCBS v1.1: (1) in 'non-inferiority studies', there is no credit for improved patient convenience, reduced patient burden or improved cosmesis; (2) in 'superiority studies' evaluating local control as a primary endpoint, there is no credit for the clinical benefit such as reduced need for further interventions. In 7/16 studies, methodological deficiencies in the conduct and reporting were identified. CONCLUSIONS: This study represents a first step in determining the utility of the ESMO-MCBS in the evaluation of clinical benefit in radiotherapy. Important shortcomings were identified that would need to be addressed in developing a version of the ESMO-MCBS that can be robustly applied to radiotherapy treatments. Optimization of the ESMO-MCBS instrument will proceed to enable assessment of value in radiotherapy.

Correlation between human ether-a-go-go-related gene channel inhibition and action potential prolongation.

BACKGROUND AND PURPOSE: Human ether-a-go-go-related gene (hERG; Kv 11.1) channel inhibition is a widely accepted predictor of cardiac arrhythmia. hERG channel inhibition alone is often insufficient to predict pro-arrhythmic drug effects. This study used a library of dofetilide derivatives to investigate the relationship between standard measures of hERG current block in an expression system and changes in action potential duration (APD) in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The interference from accompanying block of Cav 1.2 and Nav 1.5 channels was investigated along with an in silico AP model. EXPERIMENTAL APPROACH: Drug-induced changes in APD were assessed in hiPSC-CMs using voltage-sensitive dyes. The IC50 values for dofetilide and 13 derivatives on hERG current were estimated in an HEK293 expression system. The relative potency of each drug on APD was estimated by calculating the dose (D150 ) required to prolong the APD at 90% (APD90 ) repolarization by 50%. KEY RESULTS: The D150 in hiPSC-CMs was linearly correlated with IC50 of hERG current. In silico simulations supported this finding. Three derivatives inhibited hERG without prolonging APD, and these compounds also inhibited Cav 1.2 and/or Nav 1.5 in a channel state-dependent manner. Adding Cav 1.2 and Nav 1.2 block to the in silico model recapitulated the direction but not the extent of the APD change. CONCLUSIONS AND IMPLICATIONS: Potency of hERG current inhibition correlates linearly with an index of APD in hiPSC-CMs. The compounds that do not correlate have additional effects including concomitant block of Cav 1.2 and/or Nav 1.5 channels. In silico simulations of hiPSC-CMs APs confirm the principle of the multiple ion channel effects.

Association between body energy content in the dry period and post-calving production disease status in dairy cattle.

The transition from gestation to lactation is marked by significant physiological changes for the individual cow such that disease incidence is highest in early lactation. Around the time of calving, cows rely on mobilisation of body energy reserves to fill the energy deficit created by an increase in nutrient demands at a time of restricted feed intake. It is well established that monitoring of body energy reserves in lactation is an important component of herd health management. However, despite their influence on future health and productivity, monitoring of body energy reserves in the dry period is often sparse. Further, there is increasing concern that current dry off management is inappropriate for modern cattle and may influence future disease risk. This study aimed to identify candidate indicators of early lactation production disease from body energy data collected in the dry period and production data recorded at the time of dry off. Retrospective analysis was performed on 482 cow-lactations collected from a long-term Holstein-Friesian genetic and management systems project, the Langhill herd in Scotland. Cow-lactations were assigned to one of four health groups based on health status in the first 30 days of lactation. These four groups were as follows: healthy, reproductive tract disorders (retained placenta and metritis), subclinical mastitis and metabolic disorders (ketosis, hypocalcaemia, hypomagnesaemia and left displaced abomasum). ANOVA, employing a GLM was used to determine effects for the candidate indicator traits. Cows which were diagnosed with a reproductive tract disorder in the first 30 days of lactation experienced a significantly greater loss in body energy content, body condition score and weight in the preceding dry period than healthy cows. The rate of change in body energy content during the first 15 days of the dry period was -18.26 MJ/day for cows which developed reproductive tract disorder compared with +0.63 MJ/day for healthy cows. Cows diagnosed with subclinical mastitis in the first 30 days of lactation had significantly greater milk yield at dry off in the previous lactation than cows that developed a reproductive tract disorder or metabolic disease in addition to a significantly higher yield to body energy content ratio at dry off than healthy cows. Physiological and production traits recorded in the lactation and dry period preceding a disease event differed between cows which developed different diseases post-calving. Differences in these traits allow the development of new disease indicators for use in models for the prediction of disease risk in the transition period.

Infliximab vs. adalimumab in Crohn's disease: results from 327 patients in an Australian and New Zealand observational cohort study.

BACKGROUND: Maintenance anti-tumour necrosis factor-α (anti-TNFα) treatment for Crohn's disease is the standard of care for patients with an inadequate response to corticosteroids and immunomodulators. AIM: To compare the efficacy and safety of infliximab and adalimumab in clinical practice and assess the value of concomitant immunomodulator therapy. METHODS: We performed an observational cohort study in consecutive patients with Crohn's disease qualifying for anti-TNFα treatment in Australia and New Zealand between 2007 and 2011. Demographic and clinical data were prospectively recorded to identify independent factors associated with induction and maintenance of response to infliximab or adalimumab, or to either anti-TNFα therapy. RESULTS: Three hundred and twenty-seven patients (183 infliximab, 144 adalimumab) successfully applied for treatment. Eighty-nine percent responded in all groups and median maintenance of response was similar for the two agents. Concomitant immunomodulator with infliximab, but not adalimumab, demonstrated a significantly longer response overall (P = 0.002), and significantly fewer disease and treatment-related complications (P = 0.017). Corticosteroids at baseline, and/or in the preceding 12 months, were associated with a 9-13 times greater risk of disease flare during maintenance treatment as compared to no corticosteroids (P < 0.0001). Maintenance of response was similar in the anti-TNF naïve and anti-TNF experienced subgroups. CONCLUSIONS: In this large, real-life study, we demonstrate infliximab and adalimumab to have similar response characteristics. However, infliximab requires concomitant immunomodulator to achieve optimal maintenance of response comparable to adalimumab monotherapy. The results of this study will assist clinicians in further optimising patient care in their day-to-day clinical practice.

The Use of Ratiometric Fluorescence Measurements of the Voltage Sensitive Dye Di-4-ANEPPS to Examine Action Potential Characteristics and Drug Effects on Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) and higher throughput platforms have emerged as potential tools to advance cardiac drug safety screening. This study evaluated the use of high bandwidth photometry applied to voltage-sensitive fluorescent dyes (VSDs) to assess drug-induced changes in action potential characteristics of spontaneously active hiPSC-CM. Human iPSC-CM from 2 commercial sources (Cor.4U and iCell Cardiomyocytes) were stained with the VSD di-4-ANEPPS and placed in a specialized photometry system that simultaneously monitors 2 wavebands of emitted fluorescence, allowing ratiometric measurement of membrane voltage. Signals were acquired at 10 kHz and analyzed using custom software. Action potential duration (APD) values were normally distributed in cardiomyocytes (CMC) from both sources though the mean and variance differed significantly (APD90: 229 ± 15 ms vs 427 ± 49 ms [mean ± SD, P < 0.01]; average spontaneous cycle length: 0.99 ± 0.02 s vs 1.47 ± 0.35 s [mean ± SD, P < 0.01], Cor.4U vs iCell CMC, respectively). The 10-90% rise time of the AP (Trise) was ∼6 ms and was normally distributed when expressed as 1/[Formula: see text] in both cell preparations. Both cell types showed a rate dependence analogous to that of adult human cardiac cells. Furthermore, nifedipine, ranolazine, and E4031 had similar effects on cardiomyocyte electrophysiology in both cell types. However, ranolazine and E4031 induced early after depolarization-like events and high intrinsic firing rates at lower concentrations in iCell CMC. These data show that VSDs provide a minimally invasive, quantitative, and accurate method to assess hiPSC-CM electrophysiology and detect subtle drug-induced effects for drug safety screening while highlighting a need to standardize experimental protocols across preparations.

Severe hepatic dysfunction is associated with venous thromboembolic events in phase 1 clinical trials.

INTRODUCTION: Venous thromboembolic events (VTEs) are a significant cause of death in patients with cancer. The incidence of VTE is not well characterized in early phase clinical trials of novel antineoplastic agents, or in hepatic dysfunction studies designed for patients with varying degrees of liver test abnormalities. We compared the incidences of VTE in phase 1 clinical trials (P1CTs) and hepatic dysfunction trials (HDCTs) sponsored by the Cancer Therapy Evaluation Program of the National Cancer Institute (NCI) of the United States. MATERIALS & METHODS: We reviewed individual patient records of 1841 subjects for symptomatic VTE diagnosed while on study: 1328 subjects on 42 P1CTs, and 513 subjects on 9 HDCTs. The NCI's Organ Dysfunction Working Group definitions were used to categorize patients. The incidences of VTEs between patients were compared by the Chi square test. Confounders were evaluated with the Cochran-Mantel-Haenszel method. RESULTS & CONCLUSIONS: There were 43 VTEs identified among all subjects (2.3%). There were significantly more VTE observed in the subjects on P1CTs (n=38, 2.9%) than in the subjects on HDCTs (n=5, 1.0%; RR 0.341, 95% 0.13-0.86, p=0.015). For patients on HDCTs, those with severe dysfunction had a high incidence of VTE (RR 10.5 (1.12-93.6), p=0.021) that remained significant in a multivariate model. VTEs were observed less frequently in patients who were enrolled in HDCT than those who were enrolled in P1CT; however, patients with severe hepatic dysfunction were more likely to experience VTE. Severe liver test abnormalities may not be protective against VTE in patients with malignancies receiving chemotherapy.

Glucocorticoids promote structural and functional maturation of foetal cardiomyocytes: a role for PGC-1α.

Glucocorticoid levels rise dramatically in late gestation to mature foetal organs in readiness for postnatal life. Immature heart function may compromise survival. Cardiomyocyte glucocorticoid receptor (GR) is required for the structural and functional maturation of the foetal heart in vivo, yet the molecular mechanisms are largely unknown. Here we asked if GR activation in foetal cardiomyocytes in vitro elicits similar maturational changes. We show that physiologically relevant glucocorticoid levels improve contractility of primary-mouse-foetal cardiomyocytes, promote Z-disc assembly and the appearance of mature myofibrils, and increase mitochondrial activity. Genes induced in vitro mimic those induced in vivo and include PGC-1α, a critical regulator of cardiac mitochondrial capacity. SiRNA-mediated abrogation of the glucocorticoid induction of PGC-1α in vitro abolished the effect of glucocorticoid on myofibril structure and mitochondrial oxygen consumption. Using RNA sequencing we identified a number of transcriptional regulators, including PGC-1α, induced as primary targets of GR in foetal cardiomyocytes. These data demonstrate that PGC-1α is a key mediator of glucocorticoid-induced maturation of foetal cardiomyocyte structure and identify other candidate transcriptional regulators that may play critical roles in the transition of the foetal to neonatal heart.

The role of age on dose-limiting toxicities in phase I dose-escalation trials.

PURPOSE: Elderly oncology patients are not enrolled in early-phase trials in proportion to the numbers of geriatric patients with cancer. There may be concern that elderly patients will not tolerate investigational agents as well as younger patients, resulting in a disproportionate number of dose-limiting toxicities (DLT). Recent single-institution studies provide conflicting data on the relationship between age and DLT. EXPERIMENTAL DESIGN: We retrospectively reviewed data about patients treated on single-agent, dose-escalation, phase I clinical trials sponsored by the Cancer Therapy Evaluation Program (CTEP) of the National Cancer Institute. Patients' dose levels were described as a percentage of maximum tolerated dose, the highest dose level at which <33% of patients had a DLT, or recommended phase II dose (RP2D). Mixed-effect logistic regression models were used to analyze relationships between the probability of a DLT and age and other explanatory variables. RESULTS: Increasing dose, increasing age, and worsening performance status (PS) were significantly related to an increased probability of a DLT in this model (P < 0.05). There was no association between dose level administered and age (P = 0.57). CONCLUSIONS: This analysis of phase I dose-escalation trials, involving more than 500 patients older than 70 years of age, is the largest reported. As age and dose level increased and PS worsened, the probability of a DLT increased. Although increasing age was associated with occurrence of DLT, this risk remained within accepted thresholds of risk for phase I trials. There was no evidence of age bias on enrollment of patients on low or high dose levels.

Reduced aerobic capacity causes leaky ryanodine receptors that trigger arrhythmia in a rat strain artificially selected and bred for low aerobic running capacity.

AIM: Rats selectively bred for inborn low capacity of running (LCR) display a series of poor health indices, whereas rats selected for high capacity of running (HCR) display a healthy profile. We hypothesized that selection of low aerobic capacity over generations leads to a phenotype with increased diastolic Ca(2+) leak that trigger arrhythmia. METHODS: We used rats selected for HCR (N = 10) or LCR (N = 10) to determine the effect of inborn aerobic capacity on Ca(2+) leak and susceptibility of ventricular arrhythmia. We studied isolated Fura-2/AM-loaded cardiomyocytes to detect Ca(2+) handling and function on an inverted epifluorescence microscope. To determine arrhythmogenicity, we did a final experiment with electrical burst pacing in Langendorff-perfused hearts. RESULTS: Ca(2+) handling was impaired by reduced Ca(2+) amplitude, prolonged time to 50% Ca(2+) decay and reduced sarcoplasmic reticulum (SR) Ca(2+) content. Impaired Ca(2+) removal was influenced by reduced SR Ca(2+) ATP-ase 2a (SERCA2a) function and increased sodium/Ca(2+) exchanger (NCX) in LCR rats. Diastolic Ca(2) leak was 87% higher in LCR rats. The leak was reduced by CaMKII inhibition. Expression levels of phosphorylated threonine 286 CaMKII levels and increased RyR2 phosphorylation at the serine 2814 site mechanistically support our findings of increased leak in LCR. LCR rats had significantly higher incidence of ventricular fibrillation. CONCLUSION: Selection of inborn low aerobic capacity over generations leads to a phenotype with increased risk of ventricular fibrillation. Increased phosphorylation of CaMKII at serine 2814 at the cardiac ryanodine receptor appears as an important mechanism of impaired Ca(2+) handling and diastolic Ca(2+) leak that results in increased susceptibility to ventricular fibrillation.

High inborn aerobic capacity does not protect the heart following myocardial infarction.

Maximal oxygen uptake (Vo2max) is a strong prognostic marker for morbidity and mortality, but the cardio-protective effect of high inborn Vo2max remains unresolved. We aimed to investigate whether rats with high inborn Vo2max yield cardio-protection after myocardial infarction (MI) compared with rats with low inborn Vo2max. Rats breed for high capacity of running (HCR) or low capacity of running (LCR) were randomized into HCR-SH (sham), HCR-MI, LCR-SH, and LCR-MI. Vo2max was lower in HCR-MI and LCR-MI compared with respective sham (P < 0.01), supported by a loss in global cardiac function, assessed by echocardiography. Fura 2-AM loaded cardiomyocyte experiments revealed that HCR-MI and LCR-MI decreased cardiomyocyte shortening (39%, and 34% reduction, respectively, both P < 0.01), lowered Ca(2+) transient amplitude (37%, P < 0.01, and 20% reduction, respectively), and reduced sarcoplasmic reticulum (SR) Ca(2+) content (both; 20%, P < 0.01) compared with respective sham. Diastolic Ca(2+) cycling was impaired in HCR-MI and LCR-MI evidenced by prolonged time to 50% Ca(2+) decay that was partly explained by the 47% (P < 0.01) and 44% (P < 0.05) decrease in SR Ca(2+)-ATPase Ca(2+) removal, respectively. SR Ca(2+) leak increased by 177% in HCR-MI (P < 0.01) and 67% in LCR-MI (P < 0.01), which was abolished by inhibition of Ca(2+)/calmodulin-dependent protein kinase II. This study demonstrates that the effect of MI in HCR rats was similar or even more pronounced on cardiac- and cardiomyocyte contractile function, as well as on Ca(2+) handling properties compared with observations in LCR. Thus our data do not support a cardio-protective effect of higher inborn aerobic capacity.

Surgical outcomes in steroid refractory acute severe ulcerative colitis: the impact of rescue therapy.

AIM: The advent of rescue medical therapy (cyclosporin or infliximab) and laparoscopic surgery has shifted the paradigm in managing steroid refractory acute severe ulcerative colitis (ASUC). We investigated prospectively the impact of rescue therapy on timing and postoperative complications of urgent colectomy and subsequent restorative surgery for steroid refractory ASUC. METHOD: All consecutive presentations of steroid refractory ASUC at the Royal Brisbane Hospital (1996-2009) were entered in the study. Data collated included demographics, clinical and laboratory parameters on admission, medical therapy and operative and postoperative details. Steroid refractory ASUC patients undergoing immediate colectomy were compared with those failing rescue therapy and requiring same admission colectomy. RESULTS: Of 108 steroid refractory ASUC presentations, 19 (18%) received intravenous steroids only and proceeded directly to colectomy. Rescue medical therapy was instituted in 89 (82%) patients with 30 (34%) failing to respond and proceeding to colectomy. There was no significant difference in the median time from admission to colectomy for rescue therapy compared with steroid-only cases (12 vs 10 days, P = 0.70) or 30-day complication rates (27%vs 47%, P = 0.22). The interval from colectomy to a subsequent restorative procedure was significantly longer for patients who failed rescue therapy (12 vs 5 months, P = 0.02). Furthermore 30-day complications following pouch surgery were significantly higher in patients who failed rescue therapy (32%vs 0%, P = 0.01). CONCLUSION: Rescue therapy in steroid refractory ASUC is not related to delay in urgent colectomy or increased post-colectomy complications.

Transient outward K+ current reduction prolongs action potentials and promotes afterdepolarisations: a dynamic-clamp study in human and rabbit cardiac atrial myocytes.

Human atrial transient outward K(+) current (I(TO)) is decreased in a variety of cardiac pathologies, but how I(TO) reduction alters action potentials (APs) and arrhythmia mechanisms is poorly understood, owing to non-selectivity of I(TO) blockers. The aim of this study was to investigate effects of selective I(TO) changes on AP shape and duration (APD), and on afterdepolarisations or abnormal automaticity with ß-adrenergic-stimulation, using the dynamic-clamp technique in atrial cells. Human and rabbit atrial cells were isolated by enzymatic dissociation, and electrical activity recorded by whole-cell-patch clamp (35-37°C). Dynamic-clamp-simulated I(TO) reduction or block slowed AP phase 1 and elevated the plateau, significantly prolonging APD, in both species. In human atrial cells, I(TO) block (100% I(TO) subtraction) increased APD(50) by 31%, APD(90) by 17%, and APD(-61 mV) (reflecting cellular effective refractory period) by 22% (P < 0.05 for each). Interrupting I(TO) block at various time points during repolarisation revealed that the APD(90) increase resulted mainly from plateau-elevation, rather than from phase 1-slowing or any residual I(TO). In rabbit atrial cells, partial I(TO) block (∼40% I(TO) subtraction) reversibly increased the incidence of cellular arrhythmic depolarisations (CADs; afterdepolarisations and/or abnormal automaticity) in the presence of the ß-agonist isoproterenol (0.1 µm; ISO), from 0% to 64% (P < 0.05). ISO-induced CADs were significantly suppressed by dynamic-clamp increase in I(TO) (∼40% I(TO) addition). ISO+I(TO) decrease-induced CADs were abolished by ß(1)-antagonism with atenolol at therapeutic concentration (1 µm). Atrial cell action potential changes from selective I(TO) modulation, shown for the first time using dynamic-clamp, have the potential to influence reentrant and non-reentrant arrhythmia mechanisms, with implications for both the development and treatment of atrial fibrillation.

The effect of K201 on isolated working rabbit heart mechanical function during pharmacologically induced Ca2+ overload.

BACKGROUND AND PURPOSE: Reduced cardiac contractility has been associated with disrupted myocardial Ca(2+) signalling. The 1,4 benzothiazepine K201 (JTV-519) acts on several Ca(2+) handling proteins and improves cardiac contractility in vivo in a variety of animal models of myocardial dysfunction. However, it is unclear whether this improvement depends on the systemic effects of K201 or if K201 reverses the effects of Ca(2+) dysregulation, regardless of the cause. EXPERIMENTAL APPROACH: The effect of K201 on cardiac mechanical function was assessed in isolated working hearts from adult rabbits, using a ventricular pressure-volume catheter. In separate experiments, the effect of K201 was investigated in hearts following pharmacologically induced Ca(2+) overload using elevated extracellular [Ca(2+) ] ([Ca(2+) ](o) ) and ß-adrenoceptor stimulation. KEY RESULTS: K201 induced a concentration-dependent decline in systolic function (peak pressure, dP/dt(max) and preload recruitable stroke work), lusitropy (reduced dP/dt(min) and increased end diastolic pressure) and stroke volume, independent of decreased heart rate. In separate experiments, mechanical function in hearts exposed to 4.5 mmol·L(-1) [Ca(2+) ](o) and 150 nmol·L(-1) isoprenaline declined until cessation of aortic flow (in 6 out of 11 hearts). However, all hearts perfused with the addition of 1 µmol·L(-1) K201 maintained aortic flow and demonstrated significantly improved peak systolic pressures, dP/dt(max) and dP/dt(min) . CONCLUSIONS AND IMPLICATIONS: K201 significantly improved mechanical function of the heart during Ca(2+) overload. This suggests that K201 can limit the detrimental effects of elevated intracellular Ca(2+) and exert beneficial effects on cardiac contractile function, independent of systemic effects previously observed in vivo.

K201 (JTV-519) alters the spatiotemporal properties of diastolic Ca(2+) release and the associated diastolic contraction during ß-adrenergic stimulation in rat ventricular cardiomyocytes.

K201 has previously been shown to reduce diastolic contractions in vivo during ß-adrenergic stimulation and elevated extracellular calcium concentration ([Ca(2+)](o)). The present study characterised the effect of K201 on electrically stimulated and spontaneous diastolic sarcoplasmic reticulum (SR)-mediated Ca(2+) release and contractile events in isolated rat cardiomyocytes during ß-adrenergic stimulation and elevated [Ca(2+)](o). Parallel experiments using confocal microscopy examined spontaneous diastolic Ca(2+) release events at an enhanced spatiotemporal resolution. 1.0 µmol/L K201 in the presence of 150 nmol/L isoproterenol (ISO) and 4.75 mmol/L [Ca(2+)](o) significantly decreased the amplitude of diastolic contractions to ~16% of control levels. The stimulated free Ca(2+) transient amplitude was significantly reduced, but stimulated cell shortening was not significantly altered. When intracellular buffering was taken into account, K201 led to an increase in action potential-induced SR Ca(2+) release. Myofilament sensitivity to Ca(2+) was not changed by K201. Confocal microscopy revealed diastolic events composed of multiple Ca(2+) waves (2-3) originating at various points along the cardiomyocyte length during each diastolic period. 1.0 µmol/L K201 significantly reduced the (a) frequency of diastolic events and (b) initiation points/diastolic interval in the remaining diastolic events to 61% and 71% of control levels respectively. 1.0 µmol/L K201 can reduce the probability of spontaneous diastolic Ca(2+) release and their associated contractions which may limit the propensity for the contractile dysfunction observed in vivo.

Mechanisms of termination and prevention of atrial fibrillation by drug therapy.

Atrial fibrillation (AF) is a disorder of the rhythm of electrical activation of the cardiac atria. It is the most common cardiac arrhythmia, has multiple aetiologies, and increases the risk of death from stroke. Pharmacological therapy is the mainstay of treatment for AF, but currently available anti-arrhythmic drugs have limited efficacy and safety. An improved understanding of how anti-arrhythmic drugs affect the electrophysiological mechanisms of AF initiation and maintenance, in the setting of the different cardiac diseases that predispose to AF, is therefore required. A variety of animal models of AF has been developed, to represent and control the pathophysiological causes and risk factors of AF, and to permit the measurement of detailed and invasive parameters relating to the associated electrophysiological mechanisms of AF. The purpose of this review is to examine, consolidate and compare available relevant data on in-vivo electrophysiological mechanisms of AF suppression by currently approved and investigational anti-arrhythmic drugs in such models. These include the Vaughan Williams class I-IV drugs, namely Na(+) channel blockers, ß-adrenoceptor antagonists, action potential prolonging drugs, and Ca(2+) channel blockers; the "upstream therapies", e.g., angiotensin converting enzyme inhibitors, statins and fish oils; and a variety of investigational drugs such as "atrial-selective" multiple ion channel blockers, gap junction-enhancers, and intracellular Ca(2+)-handling modulators. It is hoped that this will help to clarify the main electrophysiological mechanisms of action of different and related drug types in different disease settings, and the likely clinical significance and potential future exploitation of such mechanisms.

An intestinal epithelial defect conferring ER stress results in inflammation involving both innate and adaptive immunity.

We recently characterized Winnie mice carrying a missense mutation in Muc2, leading to severe endoplasmic reticulum stress in intestinal goblet cells and spontaneous colitis. In this study, we characterized the immune responses due to this intestinal epithelial dysfunction. In Winnie, there was a fourfold increase in activated dendritic cells (DCs; CD11c(+) major histocompatibility complex (MHC) class II(hi)) in the colonic lamina propria accompanied by decreased colonic secretion of an inhibitor of DC activation, thymic stromal lymphopoietin (TSLP). Winnie also displayed a significant increase in mRNA expression of the mucosal T(H)17 signature genes Il17a, IL17f, Tgfb, and Ccr6, particularly in the distal colon. Winnie mesenteric lymph node leukocytes secreted multiple T(H)1, T(H)2, and T(H)17 cytokines on activation, with a large increase in interleukin-17A (IL-17A) progressively with age. A major source of mucosal IL-17A in Winnie was CD4(+) T lymphocytes. Loss of T and B lymphocytes in Rag1(-/-) × Winnie (RaW) crosses did not prevent spontaneous inflammation but did prevent progression with age in the colon but not the cecum. Adoptive transfer of naive T cells into RaW mice caused more rapid and severe colitis than in Rag1(-/-), indicating that the epithelial defect results in an intestinal microenvironment conducive to T-cell activation. Thus, the Winnie primary epithelial defect results in complex multicytokine-mediated colitis involving both innate and adaptive immune components with a prominent IL-23/T(H)17 response, similar to that of human ulcerative colitis.