Cat LCA-CRX model, homozygous for an antimorphic mutation has a unique phenotype

PURPOSE: Mutations in the CRX transcription factor are associated with dominant retinopathies often with more severe macular changes. The CRX-mutant cat (Rdy-A182d2) is the only animal model with the equivalent of the critical retinal region for high-acuity vision, the macula. Heterozygous cats (CRXRdy/+) have a severe phenotype modeling Leber congenital amaurosis. This study reports the distinct ocular phenotype of homozygous cats (CRXRdy/Rdy). METHODS: Gene expression changes were assessed at both mRNA and protein levels. Changes in globe morphology and retinal structure were analyzed. RESULTS: CRXRdy/Rdy cats had high levels of mutant CRX mRNA and protein. The expression of photoreceptor target genes was severely impaired although there were variable effects on the expression of other transcription factors. The photoreceptor cells remained immature and failed to elaborate outer segments consistent with the lack of retinal function. The retinal layers displayed a progressive remodeling with cell loss but maintained overall retinal thickness due to gliosis. Rapid photoreceptor loss largely occurred in the macula-equivalent retinal region. The homozygous cats developed markedly increased ocular globe length. CONCLUSIONS: The phenotype of CRXRdy/Rdy cats was more severe compared to CRXRdy/+ cats by several metrics. TRANSLATIONAL RELEVANCE: The CRX-mutant cat is the only model for CRX-retinopathies with a macula-equivalent region. A prominent feature of the CRXRdy/Rdy cat phenotype not detectable in homozygous mouse models was the rapid degeneration of the macula-equivalent retinal region highlighting the value of this large animal model and its future importance in the testing of translational therapies aiming to restore vision

Development of a protocol for maintaining viability while shipping organoid-derived retinal tissue.

Retinal organoid technology enables generation of an inexhaustible supply of three-dimensional retinal tissue from human pluripotent stem cells (hPSCs) for regenerative medicine applications. The high similarity of organoid-derived retinal tissue and transplantable human fetal retina provides an opportunity for evaluating and modeling retinal tissue replacement strategies in relevant animal models in the effort to develop a functional retinal patch to restore vision in patients with profound blindness caused by retinal degeneration. Because of the complexity of this very promising approach requiring specialized stem cell and grafting techniques, the tasks of retinal tissue derivation and transplantation are frequently split between geographically distant teams. Delivery of delicate and perishable neural tissue such as retina to the surgical sites requires a reliable shipping protocol and also controlled temperature conditions with damage-reporting mechanisms in place to prevent transplantation of tissue damaged in transit into expensive animal models. We have developed a robust overnight tissue shipping protocol providing reliable temperature control, live monitoring of the shipment conditions and physical location of the package, and damage reporting at the time of delivery. This allows for shipping of viable (transplantation-competent) hPSC-derived retinal tissue over large distances, thus enabling stem cell and surgical teams from different parts of the country to work together and maximize successful engraftment of organoid-derived retinal tissue. Although this protocol was developed for preclinical in vivo studies in animal models, it is potentially translatable for clinical transplantation in the future and will contribute to developing clinical protocols for restoring vision in patients with retinal degeneration

Sudden acquired retinal degeneration syndrome (SARDS) â a review and proposed strategies toward a better understanding of pathogenesis, early diagnosis, and therapy

Sudden acquired retinal degeneration syndrome (SARDS) is one of the leading causes of currently incurable canine vision loss diagnosed by veterinary ophthalmologists. The disease is characterized by acute onset of blindness due to loss of photoreceptor function, extinguished electroretinogram with an initially normal appearing ocular fundus, and mydriatic pupils which are slowly responsive to bright white light, unresponsive to red, but responsive to blue light stimulation. In addition to blindness, the majority of affected dogs also show systemic abnormalities suggestive of hyperadrenocorticism, such as polyphagia with resulting obesity, polyuria, polydipsia, and a subclinical hepatopathy. The pathogenesis of SARDS is unknown, but neuroendocrine and autoimmune mechanisms have been suggested. Therapies that target these disease pathways have been proposed to reverse or prevent further vision loss in SARDSâ affected dogs, but these treatments are controversial. In November 2014, the American College of Veterinary Ophthalmologists' Vision for Animals Foundation organized and funded a Think Tank to review the current knowledge and recently proposed ideas about disease mechanisms and treatment of SARDS. These panel discussions resulted in recommendations for future research strategies toward a better understanding of pathogenesis, early diagnosis, and potential therapy for this condition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122446/1/vop12291.pd

Patients and animal models of CNGβ1-deficient retinitis pigmentosa support gene augmentation approach.

Retinitis pigmentosa (RP) is a major cause of blindness that affects 1.5 million people worldwide. Mutations in cyclic nucleotide-gated channel β 1 (CNGB1) cause approximately 4% of autosomal recessive RP. Gene augmentation therapy shows promise for treating inherited retinal degenerations; however, relevant animal models and biomarkers of progression in patients with RP are needed to assess therapeutic outcomes. Here, we evaluated RP patients with CNGB1 mutations for potential biomarkers of progression and compared human phenotypes with those of mouse and dog models of the disease. Additionally, we used gene augmentation therapy in a CNGβ1-deficient dog model to evaluate potential translation to patients. CNGB1-deficient RP patients and mouse and dog models had a similar phenotype characterized by early loss of rod function and slow rod photoreceptor loss with a secondary decline in cone function. Advanced imaging showed promise for evaluating RP progression in human patients, and gene augmentation using adeno-associated virus vectors robustly sustained the rescue of rod function and preserved retinal structure in the dog model. Together, our results reveal an early loss of rod function in CNGB1-deficient patients and a wide window for therapeutic intervention. Moreover, the identification of potential biomarkers of outcome measures, availability of relevant animal models, and robust functional rescue from gene augmentation therapy support future work to move CNGB1-RP therapies toward clinical trials

Detailed histopathologic characterization of the retinopathy, globe enlarged (rge) chick phenotype

PURPOSE: The purpose of this study was to characterize the morphological abnormalities in the retinas of chicks (Gallus gallus) suffering from the autosomal recessive disease, retinopathy, globe enlarged (rge/rge). METHODS: rge/rge affected and age matched control retinas were examined from hatch up to 730 days of age. Thickness of retinal layers at six retinal regions was measured from plastic embedded sections. Morphological features were examined on semi-thin sections by light microscopy and on ultra-thin sections by transmission electron microscopy. Immunohistochemistry was performed using a panel of several different antibodies. Additionally, comparative counting of rod outer segments, rows of cells in the inner nuclear layer, and ganglion cells per unit length was performed. RESULTS: The earliest changes observed in rge/rge retinas were disorganization of the outer plexiform layer and abnormal location of the endoplasmic reticulum of the photoreceptors. In rge/rge retinas, cone pedicles were larger, irregular in shape, and usually contained multivesicular bodies. In addition, synaptic ribbons of the cone pedicles and rod spherules in rge/rge retinas were less numerous compared to controls. Large glycogen deposits progressively accumulated in the perinuclear cytoplasm associated with the abnormally located endoplasmic reticuli in accessory cones and rods. Total retinal thickness progressively decreased with age in rge/rge birds. This was accompanied by a decrease in the number of cells in the inner nuclear layer and a decrease in the number of rod outer segments (OSs). Several changes were detected in the rge/rge retinas using immunohistochemistry, including mislocalized opsin immunoreactivity of rod photoreceptors, a decrease in number and disorganization of opsin positive rod OSs (especially in the peripheral regions), a decrease in number of tyrosine hydroxylase positive neurites in the distal inner plexiform layer, and activation of macroglial and microglial cells. CONCLUSIONS: As we previously reported, the rge/rge chick has vision loss that is not the result of photoreceptor loss and is unusual in that electroretinographic responses, although abnormal, are maintained until well after vision loss has developed. The phenotype is associated with a developmental disruption of both rod and cone photoreceptor synaptic terminals that progresses with age. It is possible that these changes may be indicative of abnormal circuitry within the outer plexiform layer, and that they underlie the progressive loss of vision in rge/rge birds. Other early changes suggesting photoreceptor abnormality are dilation of photoreceptor cell bodies, abnormal positioning of endoplasmic reticulum in the perinuclear region that is associated with abnormal glycogen deposition, and mislocalization of opsin immunoreactivity in rods. The rge/rge birds develop globe enlargement after the morphological and electroretinographic abnormalities. Globe enlargement in chicks can be induced by a number of different environmental factors. It is possible that abnormal signaling of photoreceptors to inner retinal cells could induce excessive ocular growth in the rge/rge birds. Many of the morphological changes such as retinal thinning seen in older rge/rge birds may be partly the result of the considerable globe enlargement that occurs later in the disease process. Molecular genetic studies to identify the causal gene mutation should help explain the morphological features of the rge/rge phenotype and clarify their association with vision loss and electroretinographic abnormalities

Patients and animal models of CNG beta 1-deficient retinitis pigmentosa support gene augmentation approach

Retinitis pigmentosa (RP) is a major cause of blindness that affects 1.5 million people worldwide. Mutations in cyclic nucleotide-gated channel beta 1 (CNGB1) cause approximately 4% of autosomal recessive RP. Gene augmentation therapy shows promise for treating inherited retinal degenerations;however, relevant animal models and biomarkers of progression in patients with RP are needed to assess therapeutic outcomes. Here, we evaluated RP patients with CNGB1 mutations for potential biomarkers of progression and compared human phenotypes with those of mouse and dog models of the disease. Additionally, we used gene augmentation therapy in a CNG beta 1-deficient dog model to evaluate potential translation to patients. CNGB1-deficient RP patients and mouse and dog models had a similar phenotype characterized by early loss of rod function and slow rod photoreceptor loss with a secondary decline in cone function. Advanced imaging showed promise for evaluating RP progression in human patients, and gene augmentation using adeno-associated virus vectors robustly sustained the rescue of rod function and preserved retinal structure in the dog model. Together, our results reveal an early loss of rod function in CNGB1-deficient patients and a wide window for therapeutic intervention. Moreover, the identification of potential biomarkers of outcome measures, availability of relevant animal models, and robust functional rescue from gene augmentation therapy support future work to move CNGB1-RP therapies toward clinical trials

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector

Results of a search for H → τ τ decays are presented, based on the full set of proton-proton collision data recorded by the ATLAS experiment at the LHC during 2011 and 2012. The data correspond to integrated luminosities of 4.5 fb−1 and 20.3 fb−1 at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV respectively. All combinations of leptonic (τ → `νν¯ with ` = e, µ) and hadronic (τ → hadrons ν) tau decays are considered. An excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.5 (3.4) standard deviations. This excess provides evidence for the direct coupling of the recently discovered Higgs boson to fermions. The measured signal strength, normalised to the Standard Model expectation, of µ = 1.43 +0.43 −0.37 is consistent with the predicted Yukawa coupling strength in the Standard Model