Ms. Motta is a Registered Veterinary Technician and Registered Lab Animal Technician at the School of Veterinary Medicine, University of California, Davis. Her research interests include corneal wound healing, myopia and Keratoconjunctivitis Sicca. She has additional training in industry and grant project development and design, high resolution imaging and acquisition and clinical trial design and execution. Other research interests include ERG/VEP, ultrasound and tear film analysis.
Additional evidence supports GRM6 p.Thr178Met as a cause of congenital stationary night blindness in three horse breeds
Vet Ophthalmol. 2023 Oct 10. doi: 10.1111/vop.13151. Online ahead of print.
Congenital stationary night blindness (CSNB) is an ocular disorder characterized by nyctalopia. An autosomal recessive missense mutation in glutamate metabotropic receptor 6 (GRM6 c.533C>T, p.(Thr178Met)), called CSNB2, was previously identified in one Tennessee Walking Horse and predicted to reduce binding affinity of the neurotransmitter glutamate, impacting the retinal rod ON-bipolar cell signaling pathway. Thus, the first aim was to identify the allele frequency (AF) of CSNB2 in breeds with reported cases of CSNB and breeds closely related to the Tennessee Walking Horse. The second aim was to perform ocular examinations in multiple breeds to confirm the link between genotype and CSNB phenotype. In evaluating 3518 horses from 14 breeds, the CSNB2 allele was identified in nine previously unreported breeds. The estimated AF was highest in pacing Standardbreds (0.17) and lowest in American Quarter Horses (0.0010). Complete ophthalmic examinations and electroretinograms (ERG) were performed on 19 horses from three breeds, including one CSNB2 homozygote from each breed. All three CSNB2/CSNB2 horses had an electronegative ERG waveform under scotopic light conditions consistent with CSNB. The remaining 16 horses (seven CSNB2/N and nine N/N) had normal scotopic ERG results. All horses had normal photopic ERGs. This study provides additional evidence that GRM6 c.533C>T homozygosity is likely causal to CSNB in Tennessee Walking Horses, Standardbreds, and Missouri Fox Trotting Horses. Genetic testing is recommended for breeds with the CSNB2 allele to limit the production of affected horses. This study represents the largest across-breed identification of CSNB in the horse and suggests that this disorder is likely underdiagnosed.
Normal Corneal Thickness and Endothelial Cell Density in Rhesus Macaques (Macaca mulatta)
Transl Vis Sci Technol. 2022 Sep 1;11(9):23. doi: 10.1167/tvst.11.9.23.
PURPOSE: To define the normal range of central corneal thickness (CCT) and corneal endothelial cell density (ECD) in rhesus macaques (Macaca mulatta) and the effects of age, body weight, sex, and intraocular pressure (IOP) on these parameters.
METHODS: Ophthalmic examinations were performed on 144 rhesus macaques without anterior segment pathology. The CCT was measured via ultrasound pachymetry (USP) and specular microscopy, and the ECD was semiautomatically and manually counted using specular microscopy. Rebound tonometry was used to measure IOP. Linear regression and mixed-effects linear regression models were used to evaluate the effects of age, body weight, sex, and IOP on CCT and ECD.
RESULTS: We included 98 females and 46 males with an age range of 0.2 to 29.4 years. The mean CCT by USP and specular microscopy were 483 ± 39 and 463 ± 33 µm, respectively, and were statistically different (P < 0.001). The ECDs were 2717 ± 423 and 2747 ± 438 cells/mm2 by semiautomated and manual analysis, respectively. Corneal endothelial degeneration was identified in one aged rhesus macaque.
CONCLUSIONS: The mean USP and specular microscopy CCT values differed significantly, whereas the semiautomatic and manual ECD did not. The CCT was associated with the IOP and sex, whereas the ECD was associated with body weight and age (P < 0.05). As in humans, corneal disease in rhesus macaques is uncommon.
TRANSLATIONAL RELEVANCE: Establishing reference values is fundamental to use rhesus macaques as a model for corneal disease or to identify toxicity in studies of ocular drugs or devices.
In Vivo Imaging of Retinal and Choroidal Morphology and Vascular Plexuses of Vertebrates Using Swept-Source Optical Coherence Tomography
Transl Vis Sci Technol. 2022 Aug 1;11(8):11. doi: 10.1167/tvst.11.8.11.
PURPOSE: To perform in vivo evaluation of the structural morphology and vascular plexuses of the neurosensory retina and choroid across vertebrate species using swept-source optical coherence tomography (SS-OCT) and SS-OCT angiography (SS-OCTA) imaging.
METHODS: A custom-built SS-OCT system with an incorporated flexible imaging arm was used to acquire the three-dimensional (3D) retinal OCT and vascular OCTA data of five different vertebrates: a mouse (C57BL/6J), a rat (Long Evans), a gray short-tailed opossum (Monodelphis domestica), a white sturgeon (Acipenser transmontanus), and a great horned owl (Bubo virginianus).
RESULTS: In vivo structural morphology of the retina and choroid, as well as en face OCTA images of retinal and choroidal vasculature of all species were generated. The retinal morphology and vascular plexuses were similar between rat and mouse, whereas distinct choroidal and paired superficial vessels were observed in the opossum retina. The retinal and vascular structure of the sturgeon, as well as the pecten oculi and overlying the avascular and choroidal vasculature in the owl retina are reported in vivo.
CONCLUSIONS: A high-quality two-dimensional and 3D in vivo visualization of the retinal structures and en face visualization of the retina and choroidal vascular plexus of vertebrates was possible. Our studies affirm that SS-OCT and SS-OCTA are viable methods for evaluating the in vivo retinal and choroidal structure across terrestrial, aquatic, and aerial vertebrates.
TRANSLATIONAL RELEVANCE: In vivo characterization of retinal morphology and vasculature plexus of multiple species using SS-OCT and SS-OCTA imaging can increase the pool of species available as models of human retinal diseases.
Changing the Wound: Covalent Immobilization of the Epidermal Growth Factor
ACS Biomater Sci Eng. 2021 Jun 14;7(6):2649-2660. doi: 10.1021/acsbiomaterials.1c00192. Epub 2021 May 21.
Re-epithelialization of wounds is a critical element of wound closure. Growth factors have been used in combination with conventional wound management to promote closure, but the method of delivery has been limited to the topical application of ointment formulations. Cytoactive factors delivered in this way have short resident times in wounds and have met with limited success. Here, we demonstrate that methods used to covalently immobilize proteins on synthetic materials can be extended to immobilize cytoactive factors such as the epidermal growth factor (EGF) onto the wound beds of genetically diabetic mice that exhibit impaired healing. Full-thickness splinted excisional wounds were created in diabetic (db/db) mice with a well-defined silicone splint to limit wound contracture. Wound surfaces were treated with a reducing agent to expose sulfhydryl groups and subsequently treated with EGF modified with a heterobifunctional crosslinker. This allowed for the covalent immobilization of the EGF to the wound surface. The conjugation chemistry was validated in vitro and in vivo. In a separate group of mice, wounds were topically treated twice daily with soluble EGF. The mice were evaluated over 11 days for wound closure. This covalent immobilization strategy resulted in EGF being retained on the wound surface for 2 days and significantly increased epithelial wound closure by 20% compared to wounds treated with topical EGF or topical vehicle. Covalent immobilization was not only therapeutically effective but also delivered a markedly reduced load of growth factor to the wound surface compared to topical application (when only 180 ng of EGF was immobilized onto the wound surface in comparison with 7200 ng of topically applied EGF over a period of 11 days). No adverse effects were observed in treated wounds. Results obtained provide proof of concept for the effectiveness of covalent immobilization in the treatment of dysregulated wounds. The covalent immobilization of cytoactive factors represents a potentially transformative approach to the management of difficult chronic wounds.
Clinical findings and normative ocular data for free-living Anna's (Calypte anna) and Black-chinned (Archilochus alexandri) Hummingbirds
Vet Ophthalmol. 2019 Jan;22(1):13-23. doi: 10.1111/vop.12560. Epub 2018 Feb 20.
OBJECTIVE: To estimate the prevalence of ocular disease and obtain normative ocular data for free-living hummingbirds.
ANIMALS STUDIED: Two hundred and sixty-three free-living, adult Hummingbirds from coastal and inland central California were studied, including Anna's (Calypte anna, n = 186) and Black-chinned (Archilochus alexandri; n = 77) hummingbirds.
PROCEDURES: Slit lamp biomicroscopy and indirect ophthalmoscopy were performed on all individuals. Rebound tonometry, measurement of horizontal palpebral fissure length, and streak retinoscopy were performed on select individuals. Five conscious Anna's Hummingbirds underwent ocular imaging including fundus photography, digital slit lamp photography, and anterior segment and retinal optical coherence tomography.
RESULTS: The prevalence of ocular disease in this population was 2.28%. Ocular imaging revealed a thin cornea, shallow anterior chamber, large lens, and a single central, deep convexiclivate fovea. Mean ± SD intraocular pressure was 11.21 ± 2.23 mm Hg. Mean ± SD eyelid length was 2.59 ± 0.19 mm. All eyes were emmetropic or mildly hyperopic with a mean (range) ± SD refractive error of +0.32 (-0.25 to +1) ± 0.33 diopters.
CONCLUSIONS: Consistent with previous reports, these data suggest that hummingbirds have visual characteristics found in predatory and prey species, as well as a low prevalence of spontaneous ocular disease. This work provides a set of reference values and clinical findings that can be used in the future research on hummingbird vision and ocular disease. It also provides representative diagnostic images of normal birds and demonstrates that advanced ocular imaging can be performed on manually restrained hummingbirds without pharmacologic dilation.
Snake spectacle vessel permeability to sodium fluorescein
Vet Ophthalmol. 2018 Mar;21(2):119-124. doi: 10.1111/vop.12483. Epub 2017 Jun 20.
OBJECTIVE: Assess vascular permeability of the snake spectacle to sodium fluorescein during resting and shedding phases of the ecdysis cycle.
ANIMAL STUDIED: Ball python (Python regius).
PROCEDURES: The snake was anesthetized, and spectral domain optic coherence tomography was performed prior to angiographic procedures. An electronically controlled digital single-lens reflex camera with a dual-head flash equipped with filters suitable for fluorescein angiography was used to make images. Sodium fluorescein (10%) solution was administered by intracardiac injection. Angiographic images were made as fluorescein traversed the vasculature of the iris and spectacle. Individually acquired photographic frames were assessed and sequenced into pseudovideo image streams for further evaluation CONCLUSIONS: Fluorescein angiograms of the snake spectacle were readily obtained. Vascular permeability varied with the phase of ecdysis. Copious leakage of fluorescein occurred during the shedding phase. This angiographic method may provide diverse opportunities to investigate vascular aspects of snake spectacle ecdysis, dysecdysis, and the integument in general.
Intravitreal Administration of Human Bone Marrow CD34+ Stem Cells in a Murine Model of Retinal Degeneration
Invest Ophthalmol Vis Sci. 2016 Aug 1;57(10):4125-35. doi: 10.1167/iovs.16-19252.
PURPOSE: Intravitreal murine lineage-negative bone marrow (BM) hematopoietic cells slow down retinal degeneration. Because human BM CD34+ hematopoietic cells are not precisely comparable to murine cells, this study examined the effect of intravitreal human BM CD34+ cells on the degenerating retina using a murine model.
METHODS: C3H/HeJrd1/rd1 mice, immunosuppressed systemically with tacrolimus and rapamycin, were injected intravitreally with PBS (n = 16) or CD34+ cells (n = 16) isolated from human BM using a magnetic cell sorter and labeled with enhanced green fluorescent protein (EGFP). After 1 and 4 weeks, the injected eyes were imaged with scanning laser ophthalmoscopy (SLO)/optical coherence tomography (OCT) and tested with electroretinography (ERG). Eyes were harvested after euthanasia for immunohistochemical and microarray analysis of the retina.
RESULTS: In vivo SLO fundus imaging visualized EGFP-labeled cells within the eyes following intravitreal injection. Simultaneous OCT analysis localized the EGFP-labeled cells on the retinal surface resulting in a saw-toothed appearance. Immunohistochemical analysis of the retina identified EGFP-labeled cells on the retinal surface and adjacent to ganglion cells. Electroretinography testing showed a flat signal both at 1 and 4 weeks following injection in all eyes. Microarray analysis of the retina following cell injection showed altered expression of more than 300 mouse genes, predominantly those regulating photoreceptor function and maintenance and apoptosis.
CONCLUSIONS: Intravitreal human BM CD34+ cells rapidly home to the degenerating retinal surface. Although a functional benefit of this cell therapy was not seen on ERG in this rapidly progressive retinal degeneration model, molecular changes in the retina associated with CD34+ cell therapy suggest potential trophic regenerative effects that warrant further exploration.
Importance of defining experimental conditions in a mouse excisional wound model
Wound Repair Regen. 2015 Mar-Apr;23(2):251-61. doi: 10.1111/wrr.12272.
The murine dorsum dermal excisional wound model has been widely utilized with or without splint application. However, variations in experimental methods create challenges for direct comparison of results provided in the literature and for design of new wound healing studies. Here, we investigated the effects of wound location and size, number of wounds, type of adhesive used for splint fixation on wound healing using splinted or unsplinted dorsum excisional full thickness wound models. One or two 6- or 8-mm full thickness wounds were made with or without splinting in genetically diabetic but heterozygous mice (Dock7(m) + / + Lepr(db) ). Two different adhesives: tissue adhesive and an over the counter cyanoacrylate adhesive (OTCA) "Krazy glue" were used to fix splints. Wound contraction, wound closure, and histopathological parameters including reepithelialization, collagen deposition and inflammation were compared between groups. No significant effect of wound number (1 vs. 2), side (left vs. right and cranial vs. caudal) or size on wound healing was observed. The OTCA group had a significantly higher splint success compared to the tissue adhesive group that resulted in significantly higher reepithelialization and collagen deposition in the OTCA group. Understanding the outcomes and effects of the variables will help investigators choose appropriate experimental conditions for the study purpose and interpret data.
The effect of needle gauge, needle type, and needle orientation on the volume of a drop
Vet Ophthalmol. 2016 Jan;19(1):38-42. doi: 10.1111/vop.12253. Epub 2015 Jan 27.
OBJECTIVE: The purpose of this study was to determine impact of needle gauge, type, and orientation on average volume of drop dispensed.
PROCEDURE: Five needle gauges (22G, 23G, 25G, 27G, and 30G) were examined. For each gauge, volume of drop delivered was determined for standard sharp beveled tip, blunt tip, and after breaking off of the sharp needle from the hub. Vertical and horizontal orientation of the needle was tested for effect on drop volume for 22-G and 30-G sharp beveled needles.
RESULTS: Mean drop volume was affected by needle gauge, needle orientation, and whether the needle had been broken off from its hub. Mean drop volume scaled directly with needle diameter with drop volumes of 25.0 μL (±20.2) and 83.9 μL (±16.5) being found for 30-gauge and 22-gauge needles, respectively. Intermediate gauges (27, 25, 23G) yielded intermediate drop volumes. Blunt needles tended to produce larger drop volumes compared to sharp beveled needles, but these differences did not reach statistical significance. Breaking off of the needle from the hub produced substantially larger drop volumes with little difference being found between needle gauges. Average volumes of 1 drop from a 22-G vertical, 22-G horizontal, 30-G vertical, and 30-G horizontal sharp beveled needle were 20.2, 9.1, 10.1, and 3.3 μL, respectively.
CONCLUSIONS: These findings have relevance for controlled delivery of topical ophthalmic medications to patients.
PDGF-BB does not accelerate healing in diabetic mice with splinted skin wounds
PLoS One. 2014 Aug 14;9(8):e104447. doi: 10.1371/journal.pone.0104447. eCollection 2014.
Topical application of platelet-derived growth factor-BB (PDGF-BB) is considered to accelerate tissue repair of impaired chronic wounds. However, the vast literature is plagued with conflicting reports of its efficacy in animal models and this is often influenced by a wide array of experimental variables making it difficult to compare the results across the studies. To mitigate the confounding variables that influence the efficacy of topically applied PDGF-BB, we used a controlled full thickness splinted excisional wound model in db/db mice (type 2 diabetic mouse model) for our investigations. A carefully-defined silicone-splinted wound model, with reduced wound contraction, controlled splint and bandage maintenance, allowing for healing primarily by reepithelialization was employed. Two splinted 8 mm dorsal full thickness wounds were made in db/db mice. Wounds were topically treated once daily with either 3 µg PDGF-BB in 30 µl of 5% PEG-PBS vehicle or an equal volume of vehicle for 10 days. Body weights, wound contraction, wound closure, reepithelialization, collagen content, and wound bed inflammation were evaluated clinically and histopathologically. The bioactivity of PDGF-BB was confirmed by in vitro proliferation assay. PDGF-BB, although bioactive in vitro, failed to accelerate wound healing in vivo in the db/db mice using the splinted wound model. Considering that the predominant mechanism of wound healing in humans is by re-epithelialization, the most appropriate model for evaluating therapeutics is one that uses splints to prevent excessive wound contraction. Here, we report that PDGF-BB does not promote wound closure by re-epithelialization in a murine splinted wound model. Our results highlight that the effects of cytoactive factors reported in vivo ought to be carefully interpreted with critical consideration of the wound model used.
Effect of optical defocus on performance of dogs involved in field trial competition
Am J Vet Res. 2012 Apr;73(4):546-50. doi: 10.2460/ajvr.73.4.546.
OBJECTIVE: To measure the effect of induced myopia on field trial performance in dogs.
ANIMALS: 7 Labrador Retrievers and 1 Chesapeake Bay Retriever trained in field trial competition.
PROCEDURES: Dogs were commanded to retrieve targets at 137.2 m (150 yards). Each dog participated in 3 trials while their eyes were fitted with 0- (plano), +1.50-, or +3.00-diopter (D) contact lenses, applied in random order. Retrieval times were measured objectively, and dog performances were evaluated subjectively by masked judges.
RESULTS: Retrieval times were significantly faster with plano lenses than with +1.50- or +3.00-D lenses, but there were no significant differences in times between +1.50- and +3.00-D lenses. Masked judges assigned the best performance scores to dogs with plano lenses and the lowest scores to dogs fitted with +3.00-D lenses.
CONCLUSIONS AND CLINICAL RELEVANCE: Even mild myopic defocusing had a significant negative impact on both the subjective and objective assessments of dogs' performances. Dogs with demanding visual tasks or signs of visual deterioration should be evaluated retinoscopically to determine the refractive state because they may have ametropia.
Genetic analysis of Anisakis typica (Nematoda: Anisakidae) from cetaceans of the northeast coast of Brazil: new data on its definitive hosts
Vet Parasitol. 2011 Jun 10;178(3-4):293-9. doi: 10.1016/j.vetpar.2011.01.001. Epub 2011 Jan 18.
Anisakids from 5 different species of cetacean, Kogia breviceps, Peponocephala electra, Stenella clymene, Stenella longirostris and Steno bredanensis, were submitted to genetic analysis. Adults and larvae fixed in ethanol-formalin-acetic acid or in 70% ethanol for periods ranging from 10 months to 10 years were isolated from 9 cetaceans stranded on Ceará coast, Northeast Brazil. The 18S rDNA gene, ITS1, and specific Anisakis typica ITS regions were amplified by PCR. 18S rDNA and ITS1 region confirmed Anisakis sp. morphological identification but also detected the presence of Aspergillus sp. in longer preserved samples. All samples were identified as A. typica by ITS species-specific PCR. The study report three new definitive hosts of A. typica from the Brazilian Atlantic coast by genetic analysis: P. electra, K. breviceps, and S. clymene.
Participation of women in clinical trials for new drugs approved by the food and drug administration in 2000-2002
J Womens Health (Larchmt). 2009 Mar;18(3):303-10. doi: 10.1089/jwh.2008.0971.
OBJECTIVE: This study aimed to track the inclusion of women in clinical trials for new drugs approved by the Food and Drug Administration (FDA) between 2000 and 2002 and to evaluate the extent of analyses by sex.
METHODS: Data were extracted from FDA reviewers' reports, summaries of clinical trials in New Drug Applications (NDAs), and product labeling and organized into a Microsoft Access database. The information collected includes subject enrollment by sex per clinical phase and sex differences in pharmacokinetics, safety, and efficacy as determined by either sponsors or reviewers.
RESULTS: There were 67 New Molecular Entities (NMEs) approved by the FDA between 2000 and 2002. A total of 397,825 subjects were enrolled in 2,323 clinical trials. If 9 sex-specific NMEs are excluded, 297,697 subjects were enrolled in 1,974 clinical trials. Forty-seven percent of participants were male, 49% were female, and 4% of subjects were not specified. Of the 58 sex-nonspecific products in the study, 71% (41 of 58) of sex analyses were performed either by the sponsor or FDA reviewers. Twenty-five NMEs were found to have sex differences in pharmacokinetics, efficacy or adverse events. However, no recommendation was made to adjust dosage based on sex differences.
CONCLUSIONS: The percentages of women and men participating in clinical trials varied by year, phase, and product type. However, the overall participation by women and men was comparable, suggesting an improvement in including more women in clinical trials when compared with the previous FDA study evaluating women's participation from 1995 through 1999. As with the previous study, however, a significant underrepresentation of women in early phase trials and in certain areas, such as cardiovascular products, was observed and continues to be an issue of concern. Lack of appropriate analyses by sex should also be noted as an issue of concern.