The main finding of this work is that providing a relatively low cell concentration is used in IonWorks HT, the potency information generated correlates well with that determined using conventional electrophysiology. The effect on potency of increasing cell concentration may relate to a reduced free concentration of test compound owing to partitioning into cell membranes. In summary, the IonWorks HT hERG assay can generate pIC50 values based on a direct assessment of channel function in a timeframe short enough to influence chemical design.

Objective -To investigate the presence of myocardial injury in dogs hospitalized for snake envenomation and to examine its relationship with systemic inflammation.Design -Prospective case-control study.Setting -University teaching hospital and small animal referral hospital.Animals -Dogs naturally envenomed by the European viper (Vipera berus) (n=24), African puff adder (Bitis arietans) (n=5), or snouted cobra (Naja annulifera) (n=9).Interventions -Blood was collected from dogs envenomed by V. berus at admission, 12-24 hours post-admission, and 5-10 days post-admission. Blood was collected from dogs envenomed by B. arietans or N. annulifera at admission, and 12, 24, and 36 hours post-admission.Measurements and Main Results -Concentrations of cardiac troponin I (cTnI), a marker of myocardial injury, and C-reactive protein (CRP), a marker of systemic inflammation, were measured in each blood sample. Evidence of myocardial injury was found in 58% of dogs envenomed by V. berus at one or more time-points. A significant correlation between cTnI and CRP concentrations was found at all time-points. Evidence of myocardial injury was found in 80% of dogs envenomed by B. arietans at one or more time-points; however, no correlation was found between cTnI and CRP concentrations. Evidence of myocardial injury was found in 67% of dogs envenomed by N. annulifera at one or more time-points. A significant correlation between cTnI and CRP concentrations was found at admission, but not at other time-points.Conclusions -Myocardial injury frequently occurred in dogs with snake envenomation. While the degree of systemic inflammation was significantly correlated with degree of myocardial injury in V. berus envenomation at all time-points, this was not the case in dogs envenomed by N. annulifera or B. arietans. This could be due to differences in the toxic substances of the snake venoms or to differences in the cytokines induced by the venom toxins.

Atrial fibrillation (AF) is the most common tachyarrhythmia in the adult population and is a major cause of morbidity and mortality. AF can be terminated and sinus rhythm restored by prolonging the action potential duration (APD) and the refractory period. Unfortunately, antiarrhythmic agents that prolong the APD and increase the refractory period via selective inhibition of the rapid delayed rectifier potassium current (IK r ), i.e. class III antiarrhythmic drugs, are associated with an increased risk of the ventricular tachycardia Torsades de Pointes. AZD7009 is an antiarrhythmic agent with predominant actions on atrial electrophysiology that shows high antiarrhythmic efficacy and low proarrhythmic potential in animals and man. The aim of the current studies was to characterize the effect of AZD7009 on cardiac ion currents and APD in order to provide a mechanistic explanation for its predominant atrial effects and low proarrhythmic potential.The human cardiac ion channels hERG (IK r ), Kv1.5 (IK ur ), Kv4.3/KChIP2.2 (I to ), KvLQT1/minK (IK s ), Kir3.1/Kir3.4 (IK ACh ) and Nav1.5 (INa) were expressed in mammalian cells. Whole-cell currents were inhibited by AZD7009 with the following IC 50 values: hERG 0.6 μM, Nav1.5 8 μM, Kv4.3/KChIP2.2 24 μM, Kv1.5 27 μM, Kir3.1/Kir3.4 166 μM and KvLQT1/minK 193 μM. Whole-cell sodium and calcium currents were recorded in isolated rabbit atrial and ventricular myocytes using amphotericin B perforated patch. The late sodium current in rabbit atrial and ventricular myocytes was inhibited by AZD7009 in a concentration dependent way, with approximately 50% inhibition at 10 μM AZD7009. The L-type Ca 2+ current (ICa L ) in rabbit ventricular myocytes was inhibited with an IC 50 of 90 μM. Transmembrane action potentials were recorded in tissue pieces from rabbit atrium, ventricle and Purkinje fibre in control, during exposure to the selective IK r blocker E-4031 and to E-4031 in combination with AZD7009. In Purkinje fibres, but not in ventricular tissue, AZD7009 attenuated the E-4031-induced APD prolongation. In contrast, in atrial cells, AZD7009 further prolonged the APD. In addition, AZD7009 was able to suppress early afterdepolarisations (EADs) induced by E-4031 in Purkinje fibre preparations.In conclusion, AZD7009 delays repolarisation and increases refractoriness in atrial tissue through synergistic inhibition of IK r , I to , IK ur and INa, a mixed ion channel blockade that may underlie its high antiarrhythmic efficacy. Inhibition of the late sodium current, counteracting excessive APD prolongation and EADs in susceptible cells (midmyocardial and Purkinje cells), may explain the low proarrhythmic potential of AZD7009.

AZD7009 inhibits both the hERG and the hNav1.5 current, and it is most likely this combined current block that underlies the prolongation of the refractoriness and the low proarrhythmic activity demonstrated in animals in vivo.

ABSTRACT. Canine serum amyloid A (SAA) is a useful diagnostic marker of systemic inflammation. A latex agglutination turbidimetric immunoassay (LAT) was validated for automated measurements. The aim of the study was to evaluate the clinical applicability of SAA measured by the LAT. SAA was measured in 7 groups of dogs with and without systemic inflammation (n=247). Overlap performance was investigated. Diagnostic performance was compared to body temperature and leukocyte markers. Clinical decision limits for SAA were estimated. In dogs with neurological, neoplastic or gastrointestinal disorders (n=143), it was investigated whether a higher proportion of SAA positive dogs could be detected in cases of complications with risk of systemic inflammation. Significantly higher concentrations of SAA were measured in dogs with (range [48.75; 5,032 mg/l]), compared to dogs without systemic inflammation [0; 56.4 mg/l]. SAA was a more sensitive and specific marker of systemic inflammation (area under the receiver-operating characteristic curve (AUC) 1.00), compared to body temperature (0.6) and segmented neutrophils (best performing leukocyte marker, 0.84). A clinical decision limit of 56.4 mg/l was established giving close to perfect discrimination between dogs with and without systemic inflammation. Higher proportions of SAApositive dogs were observed in dogs with neurological, neoplastic and gastrointestinal disorders with complications known to increase risk of systemic inflammation, compared to uncomplicated cases. The automated LAT makes SAA applicable as a relevant diagnostic marker of systemic inflammation in dogs for routine random-access real-time use in a general clinical setting. KEY WORDS: canine, inflammation, veterinary clinical pathology.doi: 10.1292/jvms.12-0404; J. Vet. Med. Sci. 75(4): 459-466, 2013 The acute phase response (APR) is an unspecific systemic reaction, which follows various stimuli such as infection or trauma, causing systemic inflammation and disrupting homeostasis [3,21]. During the APR, the concentrations of acute phase proteins (APP) are altered [21]. Serum amyloid A (SAA) is a major positive APP in dogs, and marked increases in concentrations are consequently observed during the APR [3]. Studies in several species have shown that SAA is a more sensitive marker of systemic inflammation than traditionally used parameters such as body temperature, leukocyte and neutrophil counts [12,19], and SAA can be used as a diagnostic marker of systemic inflammation in several species, including dogs [1,4,8,21]. The commercial availability of diagnostic assays has, however, been limited to resource and time consuming methods, and so far measurements of canine SAA have not been implemented in routine veterinary clinical biochemistry [3]. The initial evaluations of an automated latex agglutination turbidimetric immunoassay (LAT, EIKEN, Tokyo, Japan), based on human monoclonal antibodies, have shown acceptable analytical and overlap performance [7], making routine diagnostic measurements of canine SAA ...