Evaluation of a method to correct the contractility index LVdP/dtmax for changes in heart rate

Thirty years of telemetry-based data acquisition for cardiovascular drug safety evaluation: Applications and optimization

Conducting safety evaluations of new drugs using conscious animals has been a specialty of our working group for thirty years. In this article, we review the various technical challenges and solutions dealt with over the years to improve both the data quality and the well being of our animal subjects. Of particular interest for us has been the use of telemetry-based data acquisition for conducting studies on cardiovascular (CV) function. This includes the evolving technical aspects of the studies, as well as the development of new applications that take advantage of this technical approach.

The impact of environmental and biological factors on the resting heart rate of dogs as assessed using 20 years of data from safety pharmacology studies

INTRODUCTION

A safety pharmacology study detects and evaluates potential side effects of a new drug on physiological function at therapeutic levels and above and, in most cases, prior to the initiation of clinical trials. The aim of this study was to investigate the effects of environmental and biological factors on resting heart rate (HR), a representative cardiac parameter in cardiovascular safety pharmacology.

METHODS

Over twenty years, 143 dogs (Beagles, Labradors and mongrels) received implanted telemetry transmitters to measure aortic pressure (AP), left ventricular pressure (LVP), Electrocardiogram (ECG) and body temperature. Throughout the 7-h period of data collection, data were continuously recorded without drug treatment and included the range of HRs resulting from spontaneous physiological changes. Statistics and visualizations were calculated using R and Spotfire.

RESULTS

Beagles had a higher HR than the mongrels, while Labradors had a lower HR than mongrels. Labradors were found to have a sex-based difference in HR, with females having a higher HR. A higher HR was observed in young animals of all breeds when they were in contact with humans. The cage system affected the HR of Labradors and mongrels more than Beagles. Larger dogs (e.g. Labrador) have a lower HR than smaller dogs (Beagles). Animals that are younger were found to have more HR variability and have a higher HR than older animals. In addition, older animals reacted less to the application period and human interaction than younger animals. The HR response of animals inside a cage system may depend on the cage system in which they were bred. A familiar cage system typically has less impact on HR.

DISCUSSION

This retrospective data base evaluation has demonstrated the impact of environmental and biological factors on cardiovascular parameters in the context of performing safety pharmacology studies. Breed, sex, age and the type of cage system used affected, at least in some cases, the HR and its variability. They should therefore be carefully considered when designing safety pharmacology studies to have the highest possible test sensitivity.

Predictive value of heart rate in patients with acute type A aortic dissection: a retrospective cohort study

OBJECTIVE

Heart rate (HR) is a risk factor of mortality in many cardiovascular diseases but no clinical studies have focused on the association between HR and prognosis in patients with acute type A aortic dissection (ATAAD). This study aimed to evaluate the association between HR and long-term mortality and establish the criteria of HR in patients with ATAAD who underwent total aortic arch replacement combined with the frozen elephant trunk (TAR+FET).

DESIGN, SETTING AND PARTICIPANTS

Retrospective cohort study that studied all consecutive patients with ATAAD who underwent TAR+FET in the Fuwai Hospital between 2009 and 2015.

MAIN OUTCOMES AND MEASURES

30-day postoperative, and estimated long-term mortality.

RESULTS

Overall, 707 patients with ATAAD who underwent TAR+FET were followed up for a median duration of 29 months (range, 5-77 months). In multivariate logistic analysis, HR (p<0.001), age (p<0.001), renal insufficiency (p=0.033), ejection fraction (p=0.005), cardiopulmonary bypass time (p<0.001) and intraoperative blood loss (p=0.002) were significantly associated with 30-day postoperative and estimated long-term mortalities. A hinge point with a sharp increase in estimated long-term mortality was identified at 80 beats/min (bpm), and compared with HR ≤80 bpm, HR >80 bpm was associated with an almost threefold higher long-term mortality. HRs ≤60, 60-70, 70-80, 80-90, 90-100, 100-110 and >110 bpm were associated with 3.9%, 4.0%, 3.8%, 7.2%, 9.5%, 10.1% and 14.4% yearly risks of death, respectively.

CONCLUSIONS

HR is a powerful predictor of long-term mortality in patients with ATAAD undergoing TAR+FET. HR >80 bpm is independently associated with elevated long-term mortality for patients with ATAAD.

Strategies to encourage the adoption of social housing during cardiovascular telemetry recordings in non-rodents

The National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) is working with industry to promote social housing during cardiovascular telemetry recordings within non-rodent safety pharmacology and toxicology studies. Following surveys to capture current practice, benefits and concerns to adoption of this refinement (2015 and 2017), a 2018 European workshop shared experience and practical advice to address common barriers such as sensitivity of different study designs and the potential for cross-contamination with test article in socially-housed conditions. A similar number of responses were received to each survey (38 in 2015; 36 in 2017), from biopharmaceutical companies and CROs that perform or outsource non-rodent telemetry studies. Each dataset had different respondents, but 19 facilities provided answers regarding dogs and non-human primates (NHPs) for both surveys. More respondents socially-housed their non-rodents in 2017; increases were apparent for both the non-recording/acclimatisation periods and the telemetry recording periods compared with 2015. However, on recording days only 60, 75 and 89% of respondents from Europe and 25, 14 and 36% of respondents from outside of Europe socially-housed their dogs, minipigs or NHPs respectively. The potential for contamination with test article between animals housed together is considered by some facilities as justification for individual housing during recordings, however, survey data did not support this rationale. Nine organisations provided data on prevalence of vomiting during telemetry studies, showing the risk was moderate for dogs and very low for minipig and NHP. Further, if vomiting did occur, this could be managed effectively with little impact on study outcomes or validity and with careful dose selection, the risk is further diminished. A recent increase in published papers and posters on this topic would suggest many more companies are planning, or have recently implemented, this refinement. The continued willingness of the community to share practical experience and publish validation data may lead to this approach becoming the 'new standard' across the industry in the near future, representing a core component of 'best-practice' recommendations to increase animal welfare whilst maintaining quality data provision for investigational and regulatory purposes.

Dietary Flaxseed Reduces Central Aortic Blood Pressure Without Cardiac Involvement but Through Changes in Plasma Oxylipins

In the year-long FlaxPAD clinical trial (Flaxseed for Peripheral Artery Disease), dietary flaxseed generated a powerful reduction in brachial systolic and diastolic blood pressure in patients with peripheral artery disease. Oxylipins were implicated as potential mechanistic mediators. However, the ability of flaxseed to impact central aortic hypertension, arterial stiffness, or cardiac performance was not investigated. Additionally, the relationship between central blood pressure (cBP) and oxylipins was not elucidated. Therefore, radial tonometry and pulse wave analysis were used to measure cBP and cardiac function in the FlaxPAD population (n=62). Plasma oxylipins were analyzed with high-performance liquid chromatography mass spectrometry. In patients with high blood pressure at baseline, the average decrease in central systolic and diastolic blood pressures versus placebo was 10 and 6 mm Hg, respectively. Flaxseed did not significantly impact augmentation index or other cardiac function indices. Alternatively, the data support several specific oxylipins as potential mediators in the antihypertensive properties of flaxseed. For example, every 1 nmol/L increase in plasma 16-hydroxyeicosatetraenoic acid increased the odds of higher central systolic and diastolic blood pressures by 12- and 9-fold, respectively. Every 1 nmol/L increase in plasma thromboxane B 2 and 5,6-dihydroxyeicosatrienoic acid increased the odds of higher cBP by 33- and 9-fold, respectively. Flaxseed induced a decrease in many oxylipins, which corresponded with a reduced risk of elevated cBP. These data extend the antihypertensive properties of flaxseed to cBP without cardiac involvement but rather through oxylipins. This study provides further support for oxylipins as therapeutic targets in hypertension.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00781950.

Social housing of non-rodents during cardiovascular recordings in safety pharmacology and toxicology studies

INTRODUCTION

The Safety Pharmacology Society (SPS) and National Centre for the Replacement, Refinement & Reduction of Animals in Research (NC3Rs) conducted a survey and workshop in 2015 to define current industry practices relating to housing of non-rodents during telemetry recordings in safety pharmacology and toxicology studies. The aim was to share experiences, canvas opinion on the study procedures/designs that could be used and explore the barriers to social housing.

METHODS

Thirty-nine sites, either running studies (Sponsors or Contract Research Organisations, CROs) and/or outsourcing work responded to the survey (51% from Europe; 41% from USA).

RESULTS

During safety pharmacology studies, 84, 67 and 100% of respondents socially house dogs, minipigs and non-human primates (NHPs) respectively on non-recording days. However, on recording days 20, 20 and 33% of respondents socially house the animals, respectively. The main barriers for social housing were limitations in the recording equipment used, study design and animal temperament/activity. During toxicology studies, 94, 100 and 100% of respondents socially house dogs, minipigs and NHPs respectively on non-recording days. However, on recording days 31, 25 and 50% of respondents socially house the animals, respectively. The main barriers for social housing were risk of damage to and limitations in the recording equipment used, food consumption recording and temperament/activity of the animals.

CONCLUSIONS

Although the majority of the industry does not yet socially house animals during telemetry recordings in safety pharmacology and toxicology studies, there is support to implement this refinement. Continued discussions, sharing of best practice and data from companies already socially housing, combined with technology improvements and investments in infrastructure are required to maintain the forward momentum of this refinement across the industry.

Evaluation of cardiac function in unrestrained dogs and monkeys using left ventricular dP/dt

INTRODUCTION

Preclinical assessment for alterations in cardiac ventricular function for drug candidates has not been a focus of ICH S7b guidelines for cardiovascular safety studies, but there is growing interest given that the cardiovascular risk is associated with positive and negative inotropes.

METHODS

From 2003 through 2013, 163 telemetry studies with left-ventricular function analyses were conducted in dogs and monkeys at Bristol Myers Squibb (BMS) in support for drug development programs. The ability of the telemetry system to detect changes in cardiac contractility was verified with positive control agents pimobendan and atenolol. Control data from a subset of studies were analyzed to determine dP/dt reference range values, and minimum detectable mean differences (control vs. treated) for statistical significance.

RESULTS

Median minimum detectable differences for dogs ranged from 14 to 21% for positive dP/dt and 11 to 21% for negative dP/dt. For monkeys, median minimum detectable differences were 25 and 14% for positive and negative dP/dt, respectively. For BMS programs, 15 drug candidates were identified that produced primary effects on contractility. Changes in contractility that were associated with, and potentially secondary to, drug-related effects on heart rate or systemic blood pressure were observed with an additional 29 drug candidates.

DISCUSSION

Changes in contractility have been observed in large animals during drug development studies at BMS over the past 10years. Model sensitivity has been demonstrated and a dP/dt beat-to-beat cloud analysis tool has been developed to help distinguish primary effects from those potentially secondary to systemic hemodynamic changes.

Rat cardiovascular telemetry: Marginal distribution applied to positive control drugs

Cardiovascular effects are considered frequent during drug safety testing. This investigation aimed to characterize the pharmacological response of the conscious telemetered rat in vivo model to known cardiovascular active agents. These effects were analyzed using statistical analysis and cloud representation with marginal distribution curves for the contractility index and heart rate as to assess the effect relationship between cardiac variables. Arterial blood pressure, left ventricular pressure, electrocardiogram and body temperature were monitored. The application of data cloud with marginal distribution curves to heart rate and contractility index provided an interesting tactic during the interpretation of drug-induced changes particularly during selective time resolution (i.e. marginal distribution curves restricted to Tmax). Taken together, the present data suggests that marginal distribution curves can be a valuable interpretation strategy when using the rat cardiovascular telemetry model to detect drug-induced cardiovascular effects. Marginal distribution curves could also be considered during the interpretation of other inter-dependent parameters in safety pharmacology studies.

Overexpression myocardial inducible nitric oxide synthase exacerbates cardiac dysfunction and beta-adrenergic desensitization in experimental hypothyroidism

BACKGROUND

Altered nitric oxide synthase (NOS) has been implicated in the pathophysiology of heart failure (HF). Recent evidence links hypothyroidism to the pathology of HF. However, the precise mechanisms are incompletely understood. The alterations and functional effects of cardiac NOS in hypothyroidism are unknown. We tested the hypothesis that hypothyroidism increases cardiomyocyte inducible NOS (iNOS) expression, which plays an important role in hypothyroidism-induced depression of cardiomyocyte contractile properties, [Ca(2+)]i transient ([Ca(2+)]iT), and β-adrenergic hyporesponsiveness.

METHODS AND RESULTS

We simultaneously evaluated LV functional performance and compared myocyte three NOS, β-adrenergic receptors (AR) and SERCA2a expressions and assessed cardiomyocyte contractile and [Ca(2+)]iT responses to β-AR stimulation with and without pretreatment of iNOS inhibitor (1400 W, 10(-5)mol/L) in 26 controls and 26 rats with hypothyroidism induced by methimazole (~30 mg/kg/day for 8 weeks in the drinking water). Compared with controls, in hypothyroidism, total serum T3 and T4 were significantly reduced followed by significantly decreased LV contractility (EES) with increased LV time constant of relaxation. These LV abnormalities were accompanied by concomitant significant decreases in myocyte contraction (dL/dtmax), relaxation (dR/dtmax), and [Ca(2+)]iT. In hypothyroidism, isoproterenol (10(-8)M) produced significantly smaller increases in dL/dtmax, dR/dtmax and [Ca(2+)]iT. These changes were associated with decreased β1-AR and SERCA2a, but significantly increased iNOS. Moreover, only in hypothyroidism, pretreatment with iNOS inhibitor significantly improved basal and isoproterenol-stimulated myocyte contraction, relaxation and [Ca(2+)]iT.

CONCLUSIONS

Hypothyroidism produces intrinsic defects of LV myocyte force-generating capacity and relaxation with β-AR desensitization. Up-regulation of cardiomyocyte iNOS may promote progressive cardiac dysfunction in hypothyroidism.

Effects of acute and chronic sunitinib treatment on cardiac function and calcium/calmodulin-dependent protein kinase II

BACKGROUND AND PURPOSE

Calcium/calmodulin-dependent protein kinase IIδ (CaMKIIδ) is an important regulator of cardiac contractile function and dysfunction and may be an unwanted secondary target for anti-cancer drugs such as sunitinib and imatinib that have been reported to alter cardiac performance. This study aimed to determine whether anti-cancer kinase inhibitors may affect CaMKII activity and expression when administered in vivo.

EXPERIMENTAL APPROACH

Cardiovascular haemodynamics in response to acute and chronic sunitinib treatment, and chronic imatinib treatment, were assessed in guinea pigs and the effects compared with those of the known positive and negative inotropes, isoprenaline and verapamil. Parallel studies from the same animals assessed CaMKIIδ expression and CaMKII activity following drug treatments.

KEY RESULTS

Acute administration of sunitinib decreased left ventricular (LV) dP/dtmax. Acute administration of isoprenaline increased LVdP/dtmax dose-dependently, while LVdP/dtmax was decreased by verapamil. CaMKII activity was decreased by acute administration of sunitinib and was increased by acute administration of isoprenaline, and decreased by acute administration of verapamil. CaMKIIδ expression following all acute treatments remained unchanged. Chronic imatinib and sunitinib treatments did not alter fractional shortening; however, both CaMKIIδ expression and CaMKII activity were significantly increased. Chronic administration of isoprenaline and verapamil decreased LV fractional shortening with parallel increases in CaMKIIδ expression and CaMKII activity.

CONCLUSIONS AND IMPLICATIONS

Chronic sunitinib and imatinib treatment increased CaMKIIδ expression and CaMKII activity. As these compounds are associated with cardiac dysfunction, increased CaMKII expression could be an early indication of cellular cardiotoxicity marking potential progression of cardiac contractile dysfunction.

The binding behavior of itraconazole with hemoglobin: studies from multi-spectroscopic techniques

The interactions between hemoglobin (Hb) and itraconazole (ITZ) are investigated in details using UV-vis spectra, circular dichroism spectroscopy, steady state fluorescence, three-dimensional fluorescence spectra, synchronous fluorescence and time-resolved fluorescence spectra at molecular level. The UV-vis studies represent that ITZ can access into heme group and lead to it explored in aqueous medium. CD spectra suggest ITZ could combine with amino acid residues in polypeptide chain and cause a partial unfolding of Hb (reducing of the α-helix content). Steady state fluorescence/synchronous fluorescence (taking into account inner filter effects) and three-dimensional fluorescence/time-resolved fluorescence spectroscopy results reveal that ITZ alters polarity and conformation around the fluorophore molecule. The interaction processes are static quenching mechanisms. The negative of ΔH(0) and ΔS(0) indicate that hydrogen bonds and van der Waals are the main force.

Methodological innovations expand the safety pharmacology horizon

Almost uniquely in pharmacology, drug safety assessment is driven by the need for elaboration and validation of methods for detecting drug actions. This is the 9th consecutive year that the Journal of Pharmacological and Toxicological Methods (JPTM) has published themed issues arising from the annual meeting of the Safety Pharmacology Society (SPS). The SPS is now past its 10th year as a distinct (from pharmacology to toxicology) discipline that integrates safety pharmacologists from industry with those in academia and the various global regulatory authorities. The themes of the 2011 meeting were (i) the bridging of safety assessment of a new chemical entity (NCE) between all the parties involved, (ii) applied technologies and (iii) translation. This issue of JPTM reflects these themes. The content is informed by the regulatory guidance documents (S7A and S7B) that apply prior to first in human (FIH) studies, which emphasize the importance of seeking model validation. The manuscripts encompass a broad spectrum of safety pharmacology topics including application of state-of-the-art techniques for study conduct and data processing and evaluation. This includes some exciting novel integrated core battery study designs, refinements in hemodynamic assessment, arrhythmia analysis algorithms, and additionally an overview of safety immunopharmacology, and a brief survey discussing similarities and differences in business models that pharmaceutical companies employ in safety pharmacology, together with SPS recommendations on 'best practice' for the conduct of a non-clinical cardiovascular assessment of a NCE.