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Purpose: Inorganic catalytic nanoceria or cerium oxide nanoparticles (CeNPs) are bona fide antioxidants that possess regenerative radical scavenging activities in vitro. Previously, we demonstrated that CeNPs had neuroprotective and anti-angiogenic properties in rodent retinal degeneration and neovascularization models. However, the cellular mechanisms and duration of the catalytic activity of CeNPs in preventing photoreceptor cell loss are still unknown. In this study, we sought to answer these questions using the P23H-1 rat, an autosomal dominant retinitis pigmentosa (adRP) model. Methods: A single dose of either saline or CeNPs was delivered intravitreally into the eyes of P23H-1 rats at 2–3 weeks of age. Retinal functions were examined at 3 to 7 weeks post injection. We quantified retinal proteins by Western blot analyses and counted the number of apoptotic (TUNEL+) profiles in the outer nuclear layer (ONL) of retinal sections. We measured free 8-isoprostanes to quantify lipid peroxidation in retinal tissues. Results: We observed increased rod and cone cell functions up to three weeks post injection. Apoptotic cells were reduced by 46%, 56%, 21%, and 24% at 3, 7, 14, 21 days, respectively, after CeNPs injection compared to saline. Additionally, reduction of lipid peroxidation in the retinas of CeNPs-treated vs saline-treated animals was detected 14 days post injection. Conclusions: We validated that CeNPs were effective in delaying loss of photoreceptor cell function in an adRP rat model. This represents the fourth rodent retinal disease model that shows delay in disease progression after a single application of CeNPs. We further demonstrated that CeNPs slowed the rate of photoreceptor cell death. We deduced that the catalytic activity of CeNPs in vivo in this rat model to be undiminished for at least 7 days and then declined over the next 14 days after CeNPs administration. [ABSTRACT FROM AUTHOR]

Cerium oxide nanoparticles (nanoceria) possess catalytic and regenerative radical scavenging activities. The ability of nanoceria to maintain cellular redox balance makes them ideal candidates for treatment of retinal diseases whose development is tightly associated with oxidative damage. We have demonstrated that our stable water-dispersed nanoceria delay photoreceptor cell degeneration in rodent models and prevent pathological retinal neovascularization in vldlr mutant mice. The objectives of the current study were to determine the temporal and spatial distributions of nanoceria after a single intravitreal injection, and to determine if nanoceria had any toxic effects in healthy rat retinas. Using inductively-coupled plasma mass spectrometry (ICP-MS), we discovered that nanoceria were rapidly taken up by the retina and were preferentially retained in this tissue even after 120 days. We also did not observe any acute or long-term negative effects of nanoceria on retinal function or cytoarchitecture even after this long-term exposure. Because nanoceria are effective at low dosages, nontoxic and are retained in the retina for extended periods, we conclude that nanoceria are promising ophthalmic therapeutics for treating retinal diseases known to involve oxidative stress in their pathogeneses. [ABSTRACT FROM AUTHOR]

Many neurodegenerative diseases are known to occur and progress because of oxidative stress, the presence of reactive oxygen species (ROS) in excess of the cellular defensive capabilities. Age related macular degeneration (AMD), diabetic retinopathy (DR) and inherited retinal degeneration share oxidative stress as a common node upstream of the blinding effects of these diseases. Knockout of the Vldlr gene results in a mouse that develops intraretinal and subretinal neovascular lesions within the first month of age and is an excellent model for a form of AMD called retinal angiomatous proliferation (RAP). Cerium oxide nanoparticles (nanoceria) catalytically scavenge ROS by mimicking the activities of superoxide dismutase and catalase. A single intravitreal injection of nanoceria into the Vldlr-/- eye was shown to inhibit: the rise in ROS in the Vldlr-/- retina, increases in vascular endothelial growth factor (VEGF) in the photoreceptor layer, and the formation of intraretinal and subretinal neovascular lesions. Of more therapeutic interest, injection of nanoceria into older mice (postnatal day 28) resulted in the regression of existing vascular lesions indicating that the pathologic neovessels require the continual production of excessive ROS. Our data demonstrate the unique ability of nanoceria to prevent downstream effects of oxidative stress in vivo and support their therapeutic potential for treatment of neurodegenerative diseases such as AMD and DR. [ABSTRACT FROM AUTHOR]

The mesencephalic and metencephalic region (MMR) of the vertebrate central nervous system develops in response to signals produced by the isthmic organizer (IsO). We have previously reported that the LIM homeobox transcription factor Lmx1b is expressed within the chick IsO, where it is sufficient to maintain expression of the secreted factor wnt1. In this paper, we show that zebrafish express two Lmx1b orthologs, lmx1b.1 and lmx1b.2, in the rostral IsO, and demonstrate that these genes are necessary for key aspects of MMR development. Simultaneous knockdown of Lmx1b.1 and Lmx1b.2 using morpholino antisense oligos results in a loss of wnt1, wnt3a, wnt10b, pax8 and fgf8 expression at the IsO, leading ultimately to programmed cell death and the loss of the isthmic constriction and cerebellum. Single morpholino knockdown of either Lmx1b.1 or Lmx1b.2 has no discernible effect on MMR development. Maintenance of lmx1b.1 and lmx1b.2 expression at the isthmus requires the function of no isthmus/pax2.1, as well as Fgf signaling. Transient misexpression of Lmx1b.1 or Lmx1b.2 during early MMR development induces ectopic wnt1 and fgf8 expression in the MMR, as well as throughout much of the embryo. We propose that Lmx1b.1- and Lmx1b.2-mediated regulation of wnt1, wnt3a, wnt10b, pax8 and fgf8 maintains cell survival in the isthmocerebellar region. [ABSTRACT FROM AUTHOR]

Extrinsic cues and intrinsic competence act in concert for cell fate determination in the developing vertebrate retina. However, what controls competence and how precise is the control are largely unknown. We studied the regulation of competence by examining the order in which individual retinal progenitor cells (RPCs) generate daughters. Experiments were performed in Xenopus laevis, whose full complement of retinal cells is formed in 2 days. We lineage-labeled RPCs at the optic vesicle stage. Subsequently we administered a cell cycle marker, 5-bromodeoxyuridine (BrdU) at early, middle or late periods of retinogenesis. Under these conditions, and in this animal, BrdU is not cleared by the time of analysis, allowing cumulative labeling. All retinal cell types were generated throughout nearly the entire retinogenesis period. When we examined the order that individual RPCs generated daughters, we discovered a regular and consistent sequence according to phenotype: RGC, Ho, CPr, RPr, Am, BP, MG. The precision of the order between the clones supports a model in which RPCs proceed through stepwise changes in competence to make each cell type, and do so unidirectionally. Because every cell type can be generated simultaneously within the same retinal environment, the change in RPC competence is likely to be autonomous. [ABSTRACT FROM AUTHOR]

Abstract: Cerium oxide nanoparticles, nanoceria, are inorganic antioxidants that have catalytic activities which mimic those of the neuroprotective enzymes superoxide dismutase and catalase. We have previously shown that nanoceria preserve retinal morphology and prevent loss of retinal function in a rat light damage model. In this study, the homozygous tubby mutant mouse, which exhibits inherited early progressive cochlear and retinal degeneration, was used as a model to test the ability of nanoceria to slow the progression of retinal degeneration. Tubby mice were injected systemically, intracardially, with 20μl of 1mM nanoceria in saline, at postnatal day 10 and subsequently at P20 and P30 whereas saline injected and uninjected wild type (or heterozygous tubby) served as injected and uninjected controls, respectively. Assays for retinal function, morphology and signaling pathway gene expression were performed on P34 mice. Our data demonstrate that nanoceria protect the retina by decreasing Reactive Oxygen Species (ROS), up-regulating the expression of neuroprotection-associated genes; down-regulating apoptosis signaling pathways and/or up-regulating survival signaling pathways to slow photoreceptor degeneration. These data suggest that nanoceria have significant potential as global agents for therapeutic treatment of inherited retinal degeneration and most types of ocular diseases. [Copyright &y& Elsevier]

Intravitreal (IVT) injection of ophthalmic therapeutics is the most widely used drug delivery route to the posterior segment of the eye. We employed this method to deliver our inorganic, catalytic antioxidant, cerium oxide nanoparticles (CeNPs), to rodent models of retinal degeneration. A single IVT of CeNPs delays disease progression. Even though we have shown that our synthesized CeNPs are retained in the retina for over a year, we still do not know which cell types in the retina preferentially take up these nanoparticles. In this study, we examined the temporal and spatial distribution of fluorescently labeled CeNPs in retinal sections after IVT. We detected elevated fluorescent signals in all the layers where retinal neurons and glia reside and retinal pigment epithelium (RPE) up to 90 days post injection. Additionally, we found that free fluorochrome accumulated in retinal vasculature instead of retinal cells. These data suggested that CeNP-conjugation mediated the targeting of the fluorochrome to retinal cells. We propose that CeNPs can be deployed as ophthalmic carriers to the retina.

Cerium oxide (CeO2) nanoparticles, CeNPs or nanoceria are inorganic and possess catalytic antioxidant activity. They scavenge reactive oxygen species and act as an oxygen buffer. Their application in industry is well-established. However, their usage as bona fide antioxidants in biological systems has been recent and is quite revolutionary. Other reviews have documented nanoceria's protective effect in reducing oxidative stress in cell culture and in animal disease models that are associated with oxidative stress. We specifically have targeted CeNPs as ophthalmic therapeutics to slow the progression of retinal degeneration and as anti-angiogenic agents in rodent models. The radical scavenging activity of CeNPs is mainly due to the dramatic increase of surface area to volume ratio in these nanocrystalline structures. The parameters for CeNPs usage in industrial settings are decidedly not suitable for biological applications. In this short review, we report the pharmacokinetics, biodistribution, and toxicity evaluation of CeNPs when applied as ophthalmic therapeutic agents in an in vivo system. We highlight studies that examine how CeNPs behave in biological environments and how they interact with bio-macromolecules. We also discuss studies that examine the dynamic changes of the surface chemistry of CeNPs in physiological buffers. Finally, we raise a list of questions that we think ought to be answered for CeNPs to be considered the antioxidants of choice in medicine, specifically in the treatment of ocular diseases.

Many neurodegenerative diseases are known to occur and progress because of oxidative stress, the presence of reactive oxygen species (ROS) in excess of the cellular defensive capabilities. Age related macular degeneration (AMD), diabetic retinopathy (DR) and inherited retinal degeneration share oxidative stress as a common node upstream of the blinding effects of these diseases. Knockout of the Vldlr gene results in a mouse that develops intraretinal and subretinal neovascular lesions within the first month of age and is an excellent model for a form of AMD called retinal angiomatous proliferation (RAP). Cerium oxide nanoparticles (nanoceria) catalytically scavenge ROS by mimicking the activities of superoxide dismutase and catalase. A single intravitreal injection of nanoceria into the Vldlr-/- eye was shown to inhibit: the rise in ROS in the Vldlr-/- retina, increases in vascular endothelial growth factor (VEGF) in the photoreceptor layer, and the formation of intraretinal and subretinal neovascular lesions. Of more therapeutic interest, injection of nanoceria into older mice (postnatal day 28) resulted in the regression of existing vascular lesions indicating that the pathologic neovessels require the continual production of excessive ROS. Our data demonstrate the unique ability of nanoceria to prevent downstream effects of oxidative stress in vivo and support their therapeutic potential for treatment of neurodegenerative diseases such as AMD and DR.

The objective of this study is to examine the glycemic response to common Chinese foods in patients with type 2 diabetes. Twenty-four Chinese adults with type 2 diabetes participated. Subjects were allocated to eat a pair of test meals in random order. Test meals included plain porridge with lean pork (meal 1A), plain porridge and Shrimp Shao Mai (Doll Brand, Winner Food Products Limited, Hong Kong) (meal 1B), boiled rice with boiled egg white (meal 2A), fried rice with whole egg (meal 2B), plain noodles in clear soup (meal 3A), and Pickled Vegetable and Pork-flavored Instant Bowl Noodles (Doll Brand, Winner Food Products Limited) (meal 3B). Nutritional content of the meals was calculated from the nutritional label on the food package and the food composition table. Plasma glucose was checked before the meal and in 30-minute intervals for up to 4 hours after the meal. Significant differences in the area under the curve of glucose up to 2 hours after the meal were detected between meal 1A and 2A ( P =.044), 1A and 3A ( P =.001), and 3A and 3B ( P =.017). The results suggest that fat alone does not alter the glycemic response to rice or porridge. Porridge produces a higher glycemic response than rice and noodles despite similar carbohydrate contents, and different noodles lead to differences in glycemic excursion, suggesting that the glycemic index of common Chinese foods is affected by cooking methods and food processing.

To understand the mechanisms of cell fate determination in the vertebrate retina, the time course of the generation of the major cell types needs to be established. This will help define and interpret patterns of gene expression, waves of differentiation, timing and extent of competence, and many of the other developmental processes involved in fate acquisition. A thorough retinal cell "birthdating" study has not been performed for the laboratory rat, even though it is the species of choice for many contemporary developmental studies of the vertebrate retina. We investigated the timing and spatial pattern of cell genesis using 3H-thymidine (3H-TdR). A single injection of 3H-TdR was administered to pregnant rats or rat pups between embryonic day (E) 8 and postnatal day (P) 13. The offspring of prenatally injected rats were delivered and all animals survived to maturity. Labeled cells were visualized by autoradiography of retinal sections. Rat retinal cell genesis commenced around E10, 50% of cells were born by approximately P1, and retinogenesis was complete near P12. The first postmitotic cells were found in the retinal ganglion cell layer and were 9-15 microm in diameter. This range includes small to medium diameter retinal ganglion cells and large displaced amacrine cells. The sequence of cell genesis was established by determining the age at which 5, 50, and 95% of the total population of cells of each phenotype became postmitotic. With few exceptions, the cell types reached these developmental landmarks in the following order: retinal ganglion cells, horizontal cells, cones, amacrine cells, rods, bipolar cells, and Müller glia. For each type, the first cells generated were located in the central retina and the last cells in the peripheral retina. Within the sequence of cell genesis, two or three phases could be detected based on differences in timing, kinetics, and topographic gradients of cell production. Our results show that retinal cells in the rat are generated in a sequence similar to that of the primate retina, in which retinogenesis spans more than 100 days. To the extent that sequences reflect underlying mechanisms of cell fate determination, they appear to be conserved., (Copyright 2004 Wiley-Liss, Inc.)