Multifocal electroretinographical changes in monkeys with experimental ocular hypertension: a longitudinal study

Purpose To study the time course of changes in the multifocal electroretinograms (mfERG) in monkeys with experimental ocular hypertension (OHT). Methods The mfERGs were recorded in 12 eyes out of 6 monkeys. Two baseline measurements were used to quantify the reproducibility, the inter-ocular and the inter-individual variability of the ERG signals. Thereafter, the trabeculum of one eye of each animal was laser-coagulated in one to three sessions to induce OHT. ERG measurements were repeated regularly in a period of 18months and the changes in ERG waveforms were quantified. Results All animals displayed OHT (between 20 and 50mmHg) in the laser-coagulated eyes. An ERG change was defined as the sum of differences during the first 90ms between the laser-coagulated eye and the same eye before laser coagulation and between the laser-coagulated eye and the non-treated fellow eye. Three animals displayed significant changes for nearly all retinal areas and all stimulus conditions. The three remaining animals displayed significant changes only in one comparison, indicating very mild changes. The data indicate that a high stimulus contrast is more sensitive to detect changes, probably because of a better signal-to-noise ratio. Moreover, the comparisons with the fellow eye are more sensitive to detect changes than comparisons with the measurements before laser-coagulation. Conclusions OHT does not always lead to ERG changes. Comparisons with fellow eyes using high contrast stimuli are more sensitive to detect changes related to OH

Magnetic resonance imaging and ultrasound elastography in the context of preclinical pharmacological research: significance for the 3R principles

The 3Rs principles—reduction, refinement, replacement—are at the core of preclinical research within drug discovery, which still relies to a great extent on the availability of models of disease in animals. Minimizing their distress, reducing their number as well as searching for means to replace them in experimental studies are constant objectives in this area. Due to its non-invasive character in vivo imaging supports these efforts by enabling repeated longitudinal assessments in each animal which serves as its own control, thereby enabling to reduce considerably the animal utilization in the experiments. The repetitive monitoring of pathology progression and the effects of therapy becomes feasible by assessment of quantitative biomarkers. Moreover, imaging has translational prospects by facilitating the comparison of studies performed in small rodents and humans. Also, learnings from the clinic may be potentially back-translated to preclinical settings and therefore contribute to refining animal investigations. By concentrating on activities around the application of magnetic resonance imaging (MRI) and ultrasound elastography to small rodent models of disease, we aim to illustrate how in vivo imaging contributes primarily to reduction and refinement in the context of pharmacological research

A consensus protocol for functional connectivity analysis in the rat brain

Task-free functional connectivity in animal models provides an experimental framework to examine connectivity phenomena under controlled conditions and allows for comparisons with data modalities collected under invasive or terminal procedures. Currently, animal acquisitions are performed with varying protocols and analyses that hamper result comparison and integration. Here we introduce StandardRat, a consensus rat functional magnetic resonance imaging acquisition protocol tested across 20 centers. To develop this protocol with optimized acquisition and processing parameters, we initially aggregated 65 functional imaging datasets acquired from rats across 46 centers. We developed a reproducible pipeline for analyzing rat data acquired with diverse protocols and determined experimental and processing parameters associated with the robust detection of functional connectivity across centers. We show that the standardized protocol enhances biologically plausible functional connectivity patterns relative to previous acquisitions. The protocol and processing pipeline described here is openly shared with the neuroimaging community to promote interoperability and cooperation toward tackling the most important challenges in neuroscience

The CEPA* industry working group’s approach to image analysis based cell proliferation studies using electronic images

Electronic images are increasingly used during the histopathology phase of toxicology studies, involving evaluations based on morphological changes for diagnosis, illustration, peer-review or reporting. In this paper we describe the approach of the European working group Cell Proliferation and Apoptosis (CEPA) for performing cell enumeration studies using electronic images. The Society of Toxicologic Pathology (STP) has published a position statement on handling of pathology image data in compliance with 21 CFR Parts 58 and 11. CEPA generally supports the STP position and shares the issues involved in the use of electronic images in pathology. However, considering the vast experience of members, particularly in conducting cell proliferation studies,, CEPA recommends that electronic images acquired using state-of-the-art slide imaging techniques, including whole slide scanning, need not be considered raw data, and therefore are not subject to 21 CFR Parts 58 and 11 regulations for archiving. In this paper, we detail the measures that are taken to ensure GLP-compliant execution of cell enumeration studies, including validation of imaging and image analysis systems and methods for their intended use and formulation and use of Standard Operating Procedures (SOPs)

Orally administered branaplam does not impact neurogenesis in juvenile mice, rats, and dogs

Branaplam is a therapeutic agent currently in clinical development for the treatment of infants with type 1 spinal muscular atrophy (SMA). Since preclinical studies showed that branaplam had cell-cycle arrest effects; we sought to determine whether branaplam may affect postnatal cerebellar development and brain neurogenesis. Here, we describe a novel approach for developmental neurotoxicity testing (DNT) of a central nervous system (CNS) active drug . The effects of orally administered branaplam were evaluated in the SMA neonatal mouse model (SMN∆7), and in juvenile Wistar Hanover rats and Beagle dogs. Histopathological examination and complementary immunohistochemical studies focused on areas of neurogenesis in the cerebellum (mice, rats, and dogs), and the subventricular zone of the striatum and dentate gyrus (rats and dogs) using antibodies directed against Ki67, phosphorylated histone H3, cleaved caspase-3, and glial fibrillary acidic protein. Additionally, image analysis based quantification of calbindin-D28k and Ki67 was performed in rats and dogs. The patterns of cell proliferation and apoptosis, and neural migration and innervation in the cerebellum and other brain regions of active adult neurogenesis did not differ between branaplam- and control-treated animals. Quantitative image analysis did not reveal any changes in calbindin-D28k and Ki67 expression in rats and dogs. The data show that orally administered branaplam has no impact on neurogenesis in juvenile animals. Application of selected immunohistochemical stainings in combination with quantitative image analysis on a few critical areas of postnatal CNS development offer a reliable approach to assess DNT of CNS-active drug candidates in juvenile animal toxicity studies

Chemokine-like receptor 1 plays a critical role in modulating the regenerative and contractile properties of muscle tissue.

Musculoskeletal diseases are a leading contributor to mobility disability worldwide. Since the majority of patients with musculoskeletal diseases present with associated muscle weakness, treatment approaches typically comprise an element of resistance training to restore physical strength. The health-promoting effects of resistance exercise are mediated via complex, multifarious mechanisms including modulation of systemic and local inflammation. Here we investigated whether targeted inhibition of the chemerin pathway, which largely controls inflammatory processes via chemokine-like receptor 1 (CMKLR1), can improve skeletal muscle function. Using genetically modified mice, we demonstrate that blockade of CMKLR1 transiently increases maximal strength during growth, but lastingly decreases strength endurance. In-depth analyses of the underlying long-term adaptations revealed microscopic alterations in the number of Pax7-positive satellite cells, as well as molecular changes in genes governing myogenesis and calcium handling. Taken together, these data provide evidence of a critical role for CMKLR1 in regulating skeletal muscle function by modulating the regenerative and contractile properties of muscle tissue. CMKLR1 antagonists are increasingly viewed as therapeutic modalities for a variety of diseases (e.g., psoriasis, metabolic disorders, and multiple sclerosis). Our findings thus have implications for the development of novel drug substances that aim at targeting the chemerin pathway for musculoskeletal or other diseases

Magnetization Transfer Ratio (MTR) as a Non-Invasive Biomarker in Small Rodent Peripheral Nerve Injury Models

The study of myelin density in peripheral nerve injuries and pathologies is largely limited to post-mortem analysis due to the difficulty in obtaining biopsies without affecting nerve function, as well as because of the small size of the tissue and its location. In this study, we used magnetization transfer ratio (MTR) MRI to longitudinally and non-invasively analyze two models of peripheral nerve injury in small rodents, obtained by sciatic nerve crush or lysolecithin injection. Multiple techniques (electrophysiology, gene expression and histology) have been used to validate the extensive MRI analysis and young and old animals have been included for comparison. This study underlines the power of MTR for the study of myelin density in small tissues such as the sciatic nerve of rodents and describes how age significantly affects recovery after injury

JAK1/2 and pan-deacetylase inhibitor combination therapy yields improved efficacy in preclinical mouse models of JAK2V617F-driven disease”

JAK inhibitors have demonstrated rapid and durable reductions in splenomegaly, as well as improvement in symptoms and quality of life in patients with myelofibrosis. However, the impact on the mutant allele burden and bone marrow fibrosis has been modest, indicating that combinations with other agents may further improve outcomes. Histone deacetylase inhibition has emerged as a promising combination modality based on in vitro studies using JAK2V617F mutant models that suggested a synergistic effect upon combination with a JAK2 inhibitor, and encouraging single-agent activity of the pan-deacetylase inhibitor panobinostat in phase I/II myelofibrosis trials. Here, we investigated the combination of the JAK1/2 inhibitor ruxolitinib and panobinostat in mouse models of JAK2V617F-driven disease. The combination was found to have a more profound effect on efficacy readouts as compared to either agent alone, and the analysis of pharmacodynamic readouts demonstrated that ruxolitinib and panobinostat have non-overlapping and complementary effects on biological pathways

JAK1/2 and pan-deacetylase inhibitor combination therapy yields improved efficacy in preclinical mouse models of JAK2V617F-driven disease

JAK inhibitors have demonstrated rapid and durable reductions in splenomegaly, as well as improvement in symptoms and quality of life in patients with myelofibrosis. However, the impact on the mutant allele burden and bone marrow fibrosis has been modest, indicating that combinations with other agents may further improve outcomes. Histone deacetylase inhibition has emerged as a promising combination modality based on in vitro studies using JAK2V617F mutant models that suggested a synergistic effect upon combination with a JAK2 inhibitor, and encouraging single-agent activity of the pan-deacetylase inhibitor panobinostat in phase I/II myelofibrosis trials. Here, we investigated the combination of the JAK1/2 inhibitor ruxolitinib and panobinostat in mouse models of JAK2V617F-driven disease. The combination was found to have a more profound effect on efficacy readouts as compared to either agent alone, and the analysis of pharmacodynamic readouts demonstrated that ruxolitinib and panobinostat have non-overlapping and complementary effects on biological pathways