Ala Moshiri

Identification of genetic elements in metabolism by high-throughput mouse phenotyping.

Metabolic diseases are a worldwide problem but the underlying genetic factors and their relevance to metabolic disease remain incompletely understood. Genome-wide research is needed to characterize so-far unannotated mammalian metabolic genes. Here, we generate and analyze metabolic phenotypic data of 2016 knockout mouse strains under the aegis of the International Mouse Phenotyping Consortium (IMPC) and find 974 gene knockouts with strong metabolic phenotypes. 429 of those had no previous link to metabolism and 51 genes remain functionally completely unannotated. We compared human orthologues of these uncharacterized genes in five GWAS consortia and indeed 23 candidate genes are associated with metabolic disease. We further identify common regulatory elements in promoters of candidate genes. As each regulatory element is composed of several transcription factor binding sites, our data reveal an extensive metabolic phenotype-associated network of co-regulated genes. Our systematic mouse phenotype analysis thus paves the way for full functional annotation of the genome.The genetic basis of metabolic diseases is incompletely understood. Here, by high-throughput phenotyping of 2,016 knockout mouse strains, Rozman and colleagues identify candidate metabolic genes, many of which are associated with unexplored regulatory gene networks and metabolic traits in human GWAS.

Morphogenetic Model for Radial Streaking in the Fundus of the Carrier State of X-Linked Albinism

A 60 year-old woman was referred for evaluation of non-specific visual complaints and abnormal fundus pigmentation. She was thought to have a possible retinal dystrophy. The patient’s complaints were limited to difficulty seeing clearly while driving at night, and difficulty seeing clearly at near. Both eyes were affected equally, and the symptoms had been present for several months. Past medical history was unremarkable for any chronic medical conditions, and she took no oral medications. The patient had no significant past ocular history. Family history was significant for a father and a son with ocular albinism. She, therefore, was an obligate carrier of this disease. Her distance and near vision were correctable to 20/20 in both eyes. Pupillary reactions were normal, as were intraocular pressures, extraocular movements, confrontational visual fields, and ocular alignment. Slit lamp examination was remarkable only for moderate nuclear sclerosis in each eye. No iris transillumination was noted on careful examination. Dilated examination revealed clear media in each eye, pink optic nerves with normally small cups, flat maculae and normal retinal vessels bilaterally. The posterior pole appeared to have a splotchy pattern of pigmentation, as seen on fundus autofluorescence (Figure 1). The peripheral fundus had alternating radial streaks of hyperpigmentation and hypopigmentation (Figure 2a) at the level of the retinal pigmented epithelium (RPE) typical of the X-linked ocular albinism carrier state. Fluorescein angiography showed normal retinal vasculature with areas of blocking and window defects corresponding to hyperpigmented and hypopigmented regions, respectively (Figure 2b). OCT scanning of the macula and full-field ERG testing were normal in both eyes. Her visual complaints were consistent with presbyopia and cataract. Figure 1 Fundus autofluorescence of the posterior pole of the right eye of the X-linked ocular albinism obligate carrier, demonstrating the typical mud-splattered appearance of the retinal pigmented epithelium (RPE). Hypoautofluorescent areas correspond to hyperpigmented ... Figure 2 Color fundus photograph (A) on a wide-angle instrument of the right eye of the X-linked ocular albinism obligate carrier, demonstrating the typical mud-splattered appearance of the posterior pole and the characteristic alternating hyperpigmented and hypopigmented ... Ocular albinism is an X-linked disease characterized in affected males by poor vision, nystagmus, iris transillumination, hypopigmented fundus, foveal hypoplasia, and an increased proportion of crossed ganglion cell fibers at the optic chiasm. Mutation of the OA1 (GPR143) gene on the X-chromosome is responsible for this condition. The skin and hair pigmentation appears clinically normal, but skin histology reveals macromelanosomes in melanocytes [1]. Carriers of the condition are rarely symptomatic, but often have signs of their carrier status. Female carriers have macromelanosomes in the skin, though they are fewer in number than in affected males. The eyes of carriers often show iris transillumination (80%) and a mud-splattered appearance of the posterior pole with typical pigmentary streaks in the peripheral fundus (92%) [2]. The pathogenesis of these streaks has not been understood. Recent studies using four-dimensional imaging with custom cell-tracking software and photoactivatable fluorophore labeling to determine the cellular dynamics underlying optic cup morphogenesis in the zebrafish shed light onto the fundus pattern in the above patient. Kwan and colleagues [3] identified two major RPE cell movements during eye development: pinwheeling and spreading. An initial pinwheel-like movement of RPE cells during the optic vesicle elongation phase gives rise to a discrete RPE domain that can be further subdivided within posterior, central and anterior subdomains (corresponding to temporal, central and nasal in humans). Immediately afterward, during optic vesicle invagination, RPE cells corresponding to the temporal and nasal domains undergo a posterior-to-anterior radial migration (spreading), while RPE cells located in the central domain maintain their relative central position. The authors replicated these studies on chick embryos, finding similar movements, thereby suggesting that optic cup morphogenesis may be evolutionarily conserved across vertebrate species. Time-lapse photography ([3]; also available online at http://www.youtube.com/watch?v=VyJ4M_1HEzY) demonstrates these dramatic movements and migration of RPE precursor cells. Bodenstein and Sidman [4] studied RPE development in mice using pigmented-albino mouse chimeras and X-inactivation mosaics. They found that posterior RPE precursors (corresponding to the central domain in zebrafish) become post-mitotic sooner than in peripheral RPE precursors. Therefore, these posterior RPE precursors stay relatively localized, allowing more “cell mixing.” Conversely, peripheral RPE precursors divide more, since they stay mitotically active longer, and add cells in an “edge-biased” fashion, producing less cell-mixing and accounting for groups of clones in the peripheral fundus. We propose that these morphogenetic movements of RPE precursors during eye development may constitute the basis of the characteristic radial streaking phenotype observed in carriers of X-linked ocular albinism. This model is based on the premise that female carriers have a mixed population of both pigmented and non-pigmented RPE precursor cells due to lyonization of the X-chromosome. During the early stages of optic vesicle development, this mixed population of RPE precursors will undergo pinwheel movements and give rise to temporal, central and nasal RPE subdomains characterized by a pigmented/non-pigmented mosaic pattern. As development proceeds, the mud-splattered pattern of the posterior pole would originate from the central RPE subdomain through the generation of localized pigmented versus non-pigmented clones by relatively fewer cell divisions and less migratory activity. On the other hand, the radial streaks seen in the periphery would originate from the posterior-to-anterior migration of RPE cells from the temporal and nasal RPE subdomains, and the “edge-biased” pattern and relatively increased mitotic activity of the peripheral clonal cell populations (Figure 3). A computer animation of the proposed model is presented in Movie 1. Further molecular histopathology in human samples and experiments in knockout mice may lend further evidence in support of this model in mammalian species. Figure 3 Schematic model of clonal populations of retinal pigmented epithelial (RPE) precursor cells proliferating and migrating in the peripheral fundus to produce the typical pattern of alternating hyperpigmented and hypopigmented streaks at the level of the ...

Venous Neovascularization in a Recipient of a Pediatric Kidney Transplant

achieve hemostasis. Intravenous heparin was restarted 1 hour after the procedure. A repeat echocardiogram obtained 24 hours later revealed improvement in right ventricular function compared with before the procedure (tricuspid annular plane systolic excursion of 2.2 cm). The patient was discharged home the following day with enoxaparin bridging to warfarin as an outpatient. Figure 6 shows the total amount of thrombus material aspirated from the patient. Percutaneous embolectomy with the FlowTriever Retrieval/Aspiration System provided rapid endovascular treatment of acute submassive PE in this higher risk patient. Acute thrombus removal may lead to more rapid hemodynamic improvement compared with catheter-directed therapy, which often takes 12–24 hours. However, the Flow Triever Retrieval/Aspiration System requires a more complex skill set and familiarity with the pulmonary anatomy as well as management of large-bore venous access and closure.

Inherited Retinal Diseases

The successful sequencing of the human genome and invention of new molecular tools such as gene modification technologies and virus-mediated gene delivery systems have changed our understanding and treatment approaches toward inherited retinal disorders. This chapter includes the most recent advances that showed potential benefits in clinical trials and brought hope for patients with visually debilitating inherited diseases.

A population study of common ocular abnormalities in C57BL/6N rd8 mice

Purpose The purpose of this study was to quantify the frequency and severity of ocular abnormalities affecting wild-type C57BL/6N mice, the most common strain used worldwide for the creation of single-gene knockouts. Methods A total of 2773 animals (5546 eyes) were examined at one colony at UC Davis and in three more colonies at the Institut Clinique de la Souris in Strasbourg, France. Mice were examined at 15 to 16 weeks postnatal age by performing anterior segment biomicroscopy, posterior segment examination by indirect ophthalmoscopy, intraocular pressure measurement, and optical coherence tomography of anterior and posterior segment structures. Results Common ocular findings in the C57BL/6N strain included corneal deposits (3%), increased optical density of the anterior lens capsule (67%), punctate nuclear cataracts (98%), vitreous crystalline deposits (61%), hyaloid vascular remnant (6%), and retinal dysplasia attributed to the rd8 mutation (58%). Interestingly, retinal dysplasia was more common in male mice in all four breeding colonies evaluated in this study. The thickness of ocular tissues and compartments were measured by spectral-domain optical coherence tomography, including the central cornea, anterior chamber, vitreous, and retinal layers. Intraocular pressure was measured by rebound tonometry. Conclusions Ocular abnormalities are common in anterior and posterior segments of the C57BL/6N mouse, the most common background on which single-gene knockout mice have been made. It is important that vision scientists understand the extent and variability of ocular findings associated with this particular genetic background of mice.

Acute Retinal Necrosis Presenting in Developmentally-delayed Patients with Neonatal Encephalitis: A Case Series and Literature Review

ABSTRACT We report three cases of patients with developmental-delay from neonatal herpetic encephalitis and/or meningitis who presented years later with acute retinal necrosis due to herpes simplex virus. The diagnosis was delayed in all cases due to the patients’ inability to verbalize their ocular complaints and cooperate with eye examinations. This case series documents the clinical course, pathophysiologic mechanism, and treatment of acute retinal necrosis in this patient population. Clinicians should understand the importance of prudent consideration of acute retinal necrosis in patients with a history of neonatal herpetic encephalitis and/or meningitis presenting with a red eye.

Senescent changes and topography of the dark-adapted multifocal electroretinogram

Purpose To investigate the topographic changes of the dark-adapted multifocal electroretinogram (mfERG) across adulthood in the central retina and compare the topography between macular versus extramacular, nasal versus temporal, and inferior versus superior retinal areas. Methods Sixty-five subjects (18–88 years) received a comprehensive dilated eye examination to ensure the health of their retina and were tested with a dark-adapted mfERG protocol using a 61-hexagon pattern. The lens absorption of each subject was also estimated using a heterochromatic flicker photometry (HFP) paradigm. Results The response amplitude and latency of the dark-adapted mfERG showed a significant change with age, which was best described with a linear model. All the retinal areas examined demonstrated similar aging effects. The extramacular and temporal retina showed higher response amplitude and faster response latency when compared with the macular and nasal retinae, respectively. No difference was found in response amplitude and latency between the inferior and superior retina. The HFP results also showed a significant correlation with age, consistent with senescent increases in short wavelength absorption by the crystalline lens. However, the change in lens absorption did not exceed the magnitude of the change in response amplitude and latency. Discussion Our results indicate that there is a decline in dark-adapted retinal activity as measured with the mfERG. These aging processes affect rods and rod-bipolar cells. Their decrease in response can be attributed to both optical and neural factors.

Arap1 deficiency causes photoreceptor degeneration in mice

Purpose Small guanosine triphosphatase (GTPase) ADP-ribosylation factors (Arfs) regulate membrane traffic and actin reorganization under the control of GTPase-activating proteins (GAPs). Arap1 is an Arf-directed GAP that inhibits the trafficking of epidermal growth factor receptor (EGFR) to the early endosome, but the diversity of its functions is incompletely understood. The aim of this study was to determine the role of Arap1 in the mammalian retina. Methods Genetically engineered Arap1 knockout mice were screened for ocular abnormalities in the National Institutes of Health Knockout Mouse Production and Phenotyping (KOMP2) Project. Arap1 knockout and wild-type eyes were imaged using optical coherence tomography and fundus photography, and analyzed by immunohistochemistry. Results Arap1−/− mice develop a normal appearing retina, but undergo photoreceptor degeneration starting at 4 weeks postnatal age. The fundus appearance of mutants is notable for pigmentary changes, optic nerve pallor, vascular attenuation, and outer retinal thinning, reminiscent of retinitis pigmentosa in humans. Immunohistochemical studies suggest the cell death is predominantly in the outer nuclear layer. Functional evaluation of the retina by electroretinography reveals amplitudes are reduced. Arap1 is detected most notably in Müller glia, and not in photoreceptors, implicating a role for Müller glia in photoreceptor survival. Conclusions Arap1 is necessary for normal photoreceptor survival in mice, and may be a novel gene relevant to human retinal degenerative processes, although its mechanism is unknown. Further studies in this mouse model of retinal degeneration will give insights into the cellular functions and signaling pathways in which Arap1 participates.