Optimisation and validation of a medium-throughput electrophysiology-based hERG assay using IonWorks™ HT

INTRODUCTION

Regulatory and competitive pressure to reduce the QT interval prolongation risk of potential new drugs has led to focus on methods to test for inhibition of the human ether-a-go-go-related gene (hERG)-encoded K+ channel, the primary molecular target underlying this safety issue. Here we describe the validation of a method that combines medium-throughput with direct assessment of channel function.

METHODS

The electrophysiological and pharmacological properties of hERG were compared using two methods: conventional, low-throughput electrophysiology and planar-array-based, medium-throughput electrophysiology (IonWorks HT). A pharmacological comparison was also made between IonWorks HT and an indirect assay (Rb+ efflux).

RESULTS

Basic electrophysiological properties of hERG were similar whether recorded conventionally (HEK cells) or using IonWorks HT (CHO cells): for example, tail current V1/2 -12.1+/-5.0 mV (32) for conventional and -9.5+/-6.0 mV (46) for IonWorks HT (mean+/-S.D. (n)). A key finding was that as the number of cells per well was increased in IonWorks HT, the potency reported for a given compound decreased. Using the lowest possible cell concentration (250,000 cells/ml) and 89 compounds spanning a broad potency range, the pIC50 values from IonWorks HT (CHO-hERG) were found to correlate well with those obtained using conventional methodology (HEK-hERG)(r=0.90; p<0.001). Further validation using CHO-hERG cells with both methods confirmed the correlation (r=0.94; p<0.001). In contrast, a comparison of IonWorks HT and Rb+ efflux data with 649 compounds using CHO-hERG cells showed that the indirect assay consistently reported compounds as being, on average, 6-fold less potent, though the differences varied depending on chemical series.

DISCUSSION

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.

Use of reconstructed computed tomography for the assessment of joint spaces in the canine elbow

OBJECTIVES

To assess the accuracy of reconstructed computed tomography for imaging canine elbow joint spaces.

METHODS

Computed tomography scans of eight cadaveric elbows were obtained and reconstructed computed tomography images were formatted in the dorsal and sagittal planes. Humeroradial and humeroulnar joint space measurements were obtained from these images. Intra-observer and inter-observer variations in joint space measurements were assessed, as was the effect of specimen positioning (inter-image variation). After freezing, four elbows were sectioned in the dorsal plane and four in the sagittal plane. In addition to visual comparison of the frozen sections with reconstructed computed tomography images, joint space measurements were obtained from frozen sections and compared with those from reconstructed computed tomography images. Variation was assessed using statistical calculations and graphical techniques.

RESULTS

Both inter-image and intra-observer analyses revealed good agreement and low variation between data sets. Inter-observer correlation was only moderate, though variation was low. Visually, the reconstructed computed tomography images accurately reflected the frozen section anatomy. Agreement between frozen section and reconstructed computed tomography joint space measurements was good, with minimal variation.

CLINICAL SIGNIFICANCE

These results indicate that reconstructed computed tomography is capable of accurately imaging elbow joint spaces and precise joint space measurements can be obtained. Reconstructed computed tomography may be useful for determining joint space measurements and detecting elbow incongruencies in dogs with elbow dysplasia.

Thoracic high-resolution computed tomographic findings in dogs with canine idiopathic pulmonary fibrosis

OBJECTIVES

To identify features of canine idiopathic pulmonary fibrosis (CIPF) using high-resolution computed tomography (HRCT), and to correlate these features with clinical stages of the disease.

METHODS

Ten dogs with signalment, history and clinical signs highly suggestive of CIPF were investigated. Thoracic radiography, haematology and biochemistry profiles, bronchoscopy and bronchoalveolar lavage and HRCT were performed in each case. The dogs were classified as having mild, moderate or severe stages of the disease based on their clinical presentation and radiographic signs. Features identified by HRCT were correlated with these disease stages.

RESULTS

HRCT showed a spectrum of pulmonary changes and it was possible to match some of these to the stage of CIPF.

CLINICAL SIGNIFICANCE

HRCT is used extensively in humans in the diagnosis and treatment planning of idiopathic pulmonary fibrosis. This preliminary study identifies the high-resolution computed tomographic features of CIPF in a small group of dogs. With further work it may be possible to use HRCT as a non-invasive tool for diagnosing, staging and therapeutically monitoring CIPF.

Histomorphometric characterisation of shared and non-shared cotyledonary villus territories of monochorionic placentae in relation to pregnancy complications

OBJECTIVE

Theoretical estimates and physiological inferences suggest that the structure of a shared cotyledon differs from a non-shared cotyledon. The aim of this study was to characterise the histomorphometry of terminal villi in shared and non-shared cotyledons in monochorionic placentae, both from uncomplicated twins and from those with twin-twin transfusion syndrome (TTTS) or discordant growth restriction (DeltaIUGR).

METHODS

Forty-one monochorionic placentae from Caucasian non-smokers were obtained at caesarean section. Their vascular anatomy and placental territories were ascertained by dye injection. After fixation, full thickness histological blocks were obtained by systematic random sampling from each twin's territory and the shared cotyledons. Fifty randomly selected terminal villi were assessed for: (i) median villus diameter (ii) median villus capillary diameter (iii) median fetomaternal diffusion distance (iv) median no. of capillaries/villus (v) degree of vascularization (median percentage cross-sectional area of terminal villi occupied by capillaries) using a stage micrometer and image analysis programme. The histomorphometric findings were then correlated with birthweight discordance, placental territory discordance and DeltaAVAs (no. of AVAs from smaller twin (donor) to larger twin (recipient) minus no. of AVAs from larger to smaller twin).

RESULTS

Histomorphometric variables were similar in shared and non-shared cotyledons of uncomplicated MCDA twins. However, the median diameter of terminal villi in shared cotyledons in DeltaIUGR and TTTS placentae was significantly smaller [51.2 microm (48.2-58.3), p<0.001 and 52.6 microm (53.1-50.4), p<0.001], and had a similar number of smaller capillaries, larger fetomaternal diffusion distance and reduced vascularization compared to non-shared IUGR and TTTS placentae. However, Deltadiameter (defined as the difference between median diameters of terminal villi in large minus small twins' territories) rose with increasing birthweight discordance (Pearson correlation coefficient=0.82, p<0.001). Multiple linear regression analysis revealed that Deltadiameter was influenced by placental territory discordance (p<0.001) and birthweight discordance (p<0.01): log10 Deltadiameter=1.38+(0.01 x birthweight discordance)+(0.56 x log10 placental territory discordance) (R2=0.82, p<0.001), but there was no significant relationship with DeltaAVA and AAA. In the TTTS group, Deltadiameter correlated significantly with DeltaAVA only: log10Deltadiameter=1.44+(0.02 x DeltaAVA) (R2=0.3, p<0.001).

CONCLUSIONS

This is the first study to characterise the histomorphometry of shared and non-shared cotyledons in MC twins. The findings suggest that abnormal placentation, rather than placental vascular anatomy may be responsible for DeltaIUGR in MC twins, whereas TTTS arises from imbalance in interfetal transfusion with resultant differing terminal villus histomorphometric features in donor, recipient and shared cotyledons.

A comparative controlled study of personality in severe obesity: a 2-y follow-up after intervention

OBJECTIVE

The primary purpose was to examine 2-y effects of weight change on personality traits in severely obese subjects treated conventionally or surgically. We also assessed differences between the severely obese patients and a primarily normal-weight reference group.

METHOD

Personality traits were assessed using 7 of 15 scales from the Karolinska Scales of Personality (KSP): Somatic Anxiety, Muscular Tension, Psychasthenia, Psychic Anxiety, Monotony Avoidance, Impulsiveness, and Irritability. A total of 1380 surgical candidates, 1241 conventionally treated patients and 1135 subjects from the SOS (Swedish Obese Subjects) reference study, representing the general population, completed the KSP. Data presented in this study were gathered twice from the patients (prior to treatment and after 2 y) and once from the reference subjects. Significance tests and effect sizes (ES) were calculated.

RESULTS

At baseline, the obese were characterised as more anxiety prone, impulsive, irritable and less monotony avoiding than the reference group; surgery patients more so than the conventionally treated. At follow-up, it was found that anxiety proneness decreased and Monotony Avoidance increased with increasing weight loss. The conventionally treated were, on average, weight stable and, hence, only a small decrease was noted regarding Somatic Anxiety. The surgery group lost on average 28 kg, and differences between surgically treated and the reference group decreased on all scales except Impulsiveness, which remained unchanged. The largest improvement was in relation to Psychasthenia.

CONCLUSIONS

Weight reduction maintained for 2 y was associated with changes on practically all personality traits in proportion to the magnitude of weight loss. In particular, Psychasthenia seemed to be alleviated, while Impulsiveness was unaffected.

Measurement-efficient optical wavemeters

We describe a method for efficiently determining the wavelength of a monochromatic source and provide an experimental proof-of-concept. The photomeasurement efficiency for a wavemeter can be written as eta(N,q) = (1 + logqN)/m, where N is the number of spectral channels, q is the number of distinguishable output levels per photodetector, and m is the actual number of photomeasurements made. An implementation is developed that achieves a theoretical efficiency of eta(N,q) = 1. The proof-of-concept experiment achieves efficiencies eta = O(1), where the deviation from theory is attributable to well-known optical effects and should be correctable in future versions.

Bone scintigraphy in the investigation of occult lameness in the dog

99mTechnetium methylene diphosphonate (99mTc-MDP) scintigraphy was performed in 14 dogs of different breeds after clinical lameness examination, radiography and synovial fluid analysis failed to localise lameness to a specific area of pain. The scintigraphic protocol included an intravenous injection of 17 MBq 99mTc-MDP/kg bodyweight and vascular, soft tissue and bone phase scans in standardised positions with a low-energy all-purpose collimator. Confirmation of diagnosis was achieved in nine dogs by arthroscopy, repeated lesion-orientated radiography, computed tomography and response to treatment. In seven cases, bone phase scans showed single elbow uptakes, in two cases unilateral limb uptake, and in one case each a single shoulder and tibia uptake; in three cases there was no increased uptake. Vascular and soft tissue phase images did not reveal additional information. Diagnosis of humeral condyle fissures, a fragmented medial coronoid process, panosteitis and arthropathy was possible in nine cases. Skeletal pathology was ruled out in three normal scintigrams. In two dogs with unilateral uptake of multiple joints, no diagnostic benefit was gained from scintigraphy. The highly sensitive and relatively specific uptake allowed localisation and characterisation or exclusion of skeletal lesions in most dogs.

Thoracic high-resolution computed tomography in the diagnosis of metastatic carcinoma

Three dogs were presented for investigation of recurrent pyrexia of unknown origin, chronic vomiting and respiratory distress, respectively. One dog was markedly underweight and the other two were cachexic. Physical examination and initial diagnostic tests failed to establish the underlying cause of the presenting signs. Thoracic radiographs were within normal limits for the age of the dog. In each case there was a high index of suspicion for an occult neoplastic process in view of the profound unexplained weight loss present. High-resolution computed tomography (HRCT) of the thorax was performed. The lung fields were divided into three zones for analysis and a novel classification scheme was used to describe the HRCT findings in each zone. Postmortem examination and histopathology confirmed the presence of an infiltrating metastatic carcinoma in all three cases. The HRCT changes correlated closely with the pathological findings. The authors conclude that HRCT of the lung should be considered for pulmonary metastatic screening in the dog and introduce a classification system for HRCT findings, based on terminology used in human medicine.

Unkonventionelle Therapien bei Krebserkrankungen im Kindesalter: Richtlinien zur Abgrenzung unbedenklicher von schädlichen Behandlungsmethoden: Ein Bericht der SIOP-Arbeitsgruppe für Psychosoziale Fragen in der Pädiatrischen Onkologie

This is the 11th official document of the SIOP Working Committee on Psychosocial Issues in Pediatric Oncology, instituted in 1991. There is a tendency for some physicians to make blanket statements against the use of non-proven, nonconventional therapies, even when these therapies are not harmful. There is an equal and opposite tendency on the part of many parents to do all that they possibly can for their children, including using any non-conventional therapy they feel might do some good. The health care team must open a healthy dialogue with parents that will lead to a clear distinction between those complementary therapies that are harmful and those that are not, indeed, might even be helpful psychologically if not therapeutically.

Predictors of treatment outcome in intermittent claudication

OBJECTIVE

To derive formulae to predict the likely 12-month health-related quality of life outcome following different treatments for intermittent claudication (IC).

DESIGN

A prospective, randomized, controlled study.

MATERIALS

One hundred and seventy-one unselected patients with stable IC were sequentially randomized to invasive therapy, supervised physical training or observation. Hierarchical analysis was used to identify significant predictors of outcome.

RESULTS

The strongest outcome predictors were baseline values of the respective outcome variables in all groups. No more than two significant secondary predictors were identified for each outcome variable and no outcome variable was a predictor of any other outcome variable. Resulting prediction equations achieved between 61 and 90% concordance with improvement (75% considered adequate), with best prediction for invasive therapy and poorest for observation. Suggested cutpoints for the various endpoints in the three groups had sensitivities ranging between 65 and 100% and false positive rates between 5 and 50%.

CONCLUSIONS

The derived equations adequately predicted improvement on the various outcome variables in invasive therapy and supervised physical training, and may serve as aids in selecting patients likely to benefit most from a particular treatment strategy. The uniqueness of the outcome variables underscores the importance of implementing a comprehensive set of endpoints relevant to the impacts of the condition.

Adefovir dipivoxil alone or in combination with lamivudine in patients with lamivudine-resistant chronic hepatitis B

BACKGROUND AND AIMS

Adefovir dipivoxil possesses potent in vitro and in vivo antiviral activity in wild-type hepatitis B. This study assessed the safety and efficacy of adefovir dipivoxil alone and in combination with lamivudine compared with ongoing lamivudine therapy in patients with chronic hepatitis B with compensated liver disease and lamivudine-resistant hepatitis B virus (HBV).

METHODS

Fifty-nine hepatitis B e antigen (HBeAg)-positive patients with genotypic evidence of lamivudine-resistant HBV, serum alanine aminotransferase (ALT) level > or =1.2 times the upper limit of normal, and serum HBV DNA level > or =6 log(10) copies/mL despite ongoing treatment with lamivudine were randomized to adefovir dipivoxil 10 mg, lamivudine 100 mg, or addition of adefovir dipivoxil to ongoing lamivudine daily. The primary end point was the time-weighted average change from baseline in serum HBV DNA level (DAVG) up to week 16.

RESULTS

Rapid reductions in serum HBV DNA level were seen by 4 weeks in all recipients of adefovir dipivoxil; DAVG(16) was -0.07 in the lamivudine group compared with -2.45 and -2.46 log(10) copies/mL in the adefovir dipivoxil/lamivudine and adefovir dipivoxil monotherapy groups, respectively (P < 0.001). Median change from baseline in serum HBV DNA level at week 48 was 0.0, -3.59, and -4.04 log(10) copies/mL in the lamivudine, adefovir dipivoxil/lamivudine, and adefovir dipivoxil groups, respectively. ALT level normalized in 10 of 19 (53%) and 9 of 18 (47%) recipients of adefovir dipivoxil/lamivudine and adefovir dipivoxil, respectively, compared with 1 of 19 (5%) recipients of lamivudine. Three patients receiving adefovir dipivoxil or adefovir dipivoxil/lamivudine and none receiving lamivudine monotherapy were HBeAg negative at week 48 and one became hepatitis B surface antigen negative.

CONCLUSIONS

These data, limited to patients with compensated liver disease, indicate that adefovir dipivoxil alone or in combination with ongoing lamivudine therapy provides effective antiviral therapy in patients with lamivudine-resistant HBV.

Comparison of ultrasonography, radiography and a single computed tomography slice for the identification of fluid within the canine tympanic bulla

Fluid accumulation within the tympanic bulla (TB) is an important diagnostic indicator in clinical cases of canine otitis media although its identification can be a challenge using currently available imaging techniques. The aim of this study was to compare ultrasound with radiography and a single computed tomography (CT) slice for the identification of fluid within the TB of canine cadavers. A random number of TB in 66 cadavers were filled with ultrasound gel. Rostrocaudal open mouth (RCdoM) radiographs and CT images were interpreted by 2 blinded radiologists and ultrasound examinations were performed by 2 blinded sonographers. The heads were then frozen and sectioned to confirm the contents of each TB. Although CT remained the most accurate method, comparable results were obtained by one of the sonographers and even the inexperienced sonographer produced results superior to radiography. Ultrasound has several advantages over the other imaging techniques and this study suggests that it may have an application in the investigation of canine otitis media although further work in live animals would be required to confirm this.

Severe obesity and personality: a comparative controlled study of personality traits

OBJECTIVE

The primary purpose was to assess personality trait differences between the severely obese seeking treatment and a mainly non-obese reference group. We also investigated gender differences and differences between obese patients and obese not seeking treatment.

METHOD

Personality traits were assessed using 7 of 15 scales from the Karolinska Scales of Personality (KSP): Somatic Anxiety, Muscular Tension, Psychastenia, Psychic Anxiety, Monotony Avoidance, Impulsiveness, and Irritability. Patients from the Swedish Obese Subjects (SOS) intervention study (n=3270, ages 37-57, 71% women) and the SOS reference study (n=1135, 54% women) completed the survey. Data presented in this study were gathered prior to treatment. Significance tests and effects sizes were calculated.

RESULTS

Although statistically significant differences were found between obese patients and reference subjects on nearly all personality traits, effect sizes were at most moderate. Of the three scales with moderate effects sizes, differences on Somatic Anxiety and Psychastenia could be traced to items tapping condition-specific symptoms, e.g., problems with sweating and breathing as indicators of Somatic Anxiety. Moderate differences on the Impulsiveness scale (men alone) could not be explained by item composition. Further, the obese patients differed from obese in the reference group, and both obese and reference women reported significantly higher levels on Somatic Anxiety, Muscular Tension and Psychic Anxiety compared to men (effect size: small).

CONCLUSIONS

Our results provided no evidence of a general obese personality profile, instead considerable heterogeneity in personality traits was observed across our obese samples (treatment seekers vs non-seekers, men vs women) and generally only small differences were noted compared to a reference study population. Further research is needed to investigate if the somewhat elevated levels of Impulsiveness, particularly among male obese patients, is affected by weight loss. When assessing personality traits in diseased groups consideration should be given to possible confounding from, e.g., somatic symptoms.

Ultrasound imaging of the canine tympanic bulla

A procedure for imaging the canine tympanic bulla, external ear canal and adjacent structures using currently available ultrasound equipment was established. Lateral and ventral transducer positions were identified for this purpose and a 6.5 MHz curvilinear transducer was considered to be optimal. The sonographic appearance of these structures in cadavers and live dogs unaffected by ear disease is documented. Fluid was introduced into the tympanic bullae of the cadavers and its presence could be identified through the bony wall of the bulla. The ability of ultrasound to differentiate between gas and fluid within the bulla has important clinical implications as this is a common occurrence in dogs with middle ear disease. Ultrasound has several advantages over other imaging modalities and the examination procedure was well tolerated by unsedated dogs.