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| 2. |
- Ahuja, Sat pal, et al.
(författare)
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Serum-free retinal explant culture system and comparative rescue effects of LEDGF, GST, CNTF, BDNF, NGF, bFGF and antioxidants in the rd1 mouse model of retinitis pigmentosa
- 2009
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Ingår i: Retinal Degeneration: Causes, Diagnosis and Treatment. - 9781607410072 ; , s. 263-299
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Bokkapitel (refereegranskat)abstract
- Retinitis pigmentosa is a group of inherited retinal degenerative diseases characterized by the loss of photoreceptors and vision for which no effective treatment is available. Several animal models of retinitis pigmentosa are used to elucidate its pathogenesis and to devise therapies. The retinal degeneration (rd1) mouse is one such animal model in which rod-specific phosphodiesterase (PDE) is inactive due to a mutation in the β-subunit of the Pde gene (Pde6brd1). This mutation leads to increased levels of retinal cyclic guanosine monophosphate (cGMP) and Ca2+ ions and eventually retinal degeneration by increased oxidative stress, activation of poly-(ADP-ribose)-polymerase-1 and proteinases including calpains and caspases. However, diverse overlapping mechanism(s) of cell death have been described. An in vitro retinal explant culture system was developed, as results of studies involving isolated retinal cells and the in vivo models are difficult to interpret. Neonatal and postnatal retinas of wild type (wt) and rd1 mice were cultured successfully in a serum-free medium containing bovine serum albumin. The cultured wt and rd1 retinas respectively developed and degenerated in ways similar to the age-matched in vivo retinas of the two genotypes. This was confirmed from the similar retinal lamination pattern, expression and immunohistochemical localization of opsin, rhodopsin, arrestin, interphotoreceptor retinol-binding protein and calcium-binding protein markers, namely, calbindin, parvalbumin and calretinin in age-matched in vivo and cultured retinas of both genotypes. Horizontal cell fibers and Mueller cells of in vivo retina showed the presence of α-and μ-glutathione-S-transferases (GST). In rd1 mouse retina, GST and glutathione peroxidase (GPx) levels were lower than those in wt and suggested an oxidative stress. The photoreceptor rescue effects of lens epithelium-derived growth factor (LEDGF), α-GST, and μ-GST; and ciliary neurotrophic factor (CNTF), brain-derived growth factor (BDNF), nerve growth factor (NGF), basic fibroblast growth factor (bFGF); and antioxidants (lutein, zeaxanthin, glutathione and α-lipoic acid) were compared after supplementation in a serum-free retina organ culture system. The above combination of antioxidants rescued the rd1 photoreceptors both under in vitro and in vivo conditions. The maximum photoreceptors rescue was by CNTF + BDNF, whereas that by NGF + bFGF was intermediate. CNTF, BDNF, NGF, and bFGF individually rescued the photoreceptors, but their effect was less than those of their combinations. LEDGF and GST supplementation in vitro delayed rod photoreceptor degeneration in postnatal day-2 (PN2) and PN7 rd1 explants cultured in vitro for 26 and 21 days, respectively, possibly by reversing the oxidative stress. The latter was confirmed from the lower levels of GPx and from the rescue of rd1 photoreceptors by in vitro and in vivo supplementation with LEDGF or the combination of antioxidants. Individual antioxidants were ineffective in rescuing the photoreceptors under in vivo and in vitro conditions.
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| 3. |
- Azadi, Seifollah, et al.
(författare)
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CNTF plus BDNF treatment and neuroprotective pathways in the rd1 mouse retina
- 2007
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Ingår i: Brain Research. - : Elsevier BV. - 1872-6240 .- 0006-8993. ; 1129:1, s. 116-129
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Tidskriftsartikel (refereegranskat)abstract
- The rd1 mouse is a relevant model for studying the mechanisms of photoreceptor degeneration in retinitis pigmentosa. Treatment with ciliary neurotrophic factor (CNTF) in combination with brain derived neurotrophic factor (BDNF) is known to rescue photoreceptors in cultured rd1 retinal explants. To shed light on the underlying mechanisms, we studied the effects of 9 days (starting at postnatal day 2) in vitro CNTF+BDNF treatment on the endogenous production of CNTF, BDNF, fibroblast growth factor 2 (FGF2), or the activation of extracellular signal-regulated kinase (ERK), Akt and CAMP-response-element-binding protein (CREB) in retinal explants. In rd1 explants, CNTF+BDNF decreased the number of TUNEL-positive photoreceptors. The treatment also increased endogenous rd1 levels of CNTF and BDNF, but lowered the level of FGF2 expression in rd1 explants. When wild-type explants were treated, endogenous CNTF was similarly increased, while BDNF and FGF2 levels remained unaffected. In addition, treatment of rd1 retinas strongly increased the phosphorylation of ERK, Akt and CREB. In treated wild-type explants, the same parameters were either unchanged (ERK) or decreased (Akt and CREB). The results suggest a role for Akt, ERK and CREB in conveying the neuroprotective effect of CNTF+BDNF treatment in rd1 retinal explants. (c) 2006 Elsevier B.V. All rights reserved.
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| 5. |
- Békassy, Zivile, et al.
(författare)
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Intestinal damage in enterohemorrhagic Escherichia coli infection.
- 2011
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Ingår i: Pediatric Nephrology. - : Springer Science and Business Media LLC. - 1432-198X .- 0931-041X. ; oct, s. 2059-2071
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Tidskriftsartikel (refereegranskat)abstract
- Enterohemorrhagic Escherichia coli (EHEC) infection leads to marked intestinal injury. Sigmoid colon obtained from two children during EHEC infection exhibited abundant TUNEL-positive cells. To define which bacterial virulence factors contribute to intestinal injury the presence of Shiga toxin-2 (Stx2), intimin and the type III secretion system were correlated with symptoms and intestinal damage. C3H/HeN mice were inoculated with Stx2-producing (86-24) and non-producing (87-23) E. coli O157:H7 strains and 86-24 mutants lacking eae, encoding intimin (strain UMD619) or escN regulating the expression of type III secretion effectors (strain CVD451). Severe symptoms developed in mice inoculated with 86-24 and 87-23. Few mice inoculated with the mutant strains developed severe symptoms. Strain 86-24 exhibited higher fecal bacterial counts, followed by 87-23, whereas strains UMD619 and CVD451 showed minimal fecal counts. More TUNEL-positive cells were found in proximal and distal colons of mice inoculated with strain 86-24 compared with strains 87-23 and CVD451 (p
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| 6. |
- Gesslein, Bodil, et al.
(författare)
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Mitogen-activated protein kinases in the porcine retinal arteries and neuroretina following retinal ischemia-reperfusion.
- 2010
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Ingår i: Molecular Vision. - 1090-0535. ; 16, s. 392-407
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of the present study was to examine changes in the expression of intracellular signal-transduction pathways, specifically mitogen-activated protein kinases, following retinal ischemia-reperfusion. METHODS: Retinal ischemia was induced by elevating the intraocular pressure in porcine eyes, followed by 5, 12, or 20 h of reperfusion. The results were compared to those of the sham- operated fellow eye. The retinal arteries and neuroretina were isolated separately and examined. Tissue morphology and DNA fragmentation were studied using histology. Extracellular signal-regulated kinase 1 and 2 (ERK1/2), p38, c-junNH(2)-terminal kinases (JNK), and c-jun protein and mRNA expression were examined using immunofluorescence staining, western blot, and real-time PCR techniques. RESULTS: Pyknotic cell nuclei, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells, and glial fibrillary acidic protein mRNA expression were increased in ischemia, suggesting injury. Phosphorylated ERK1/2 protein levels were increased in the neuroretina following ischemia, while mRNA levels were unaltered. p38 protein and mRNA levels were not affected by ischemia. Immunofluorescence staining for phosphorylated p38 was especially intense in the retinal blood vessels, while only weak in the neuroretina. Phosphorylated JNK protein and mRNA were slightly decreased in ischemia. Phosphorylated c-jun protein and mRNA levels were higher in the neuroretina after ischemia-reperfusion. CONCLUSIONS: Retinal ischemia-reperfusion alters expression of mitogen-activated protein kinases, particularly ERK1/2, in the neuroretina and retinal arteries. The development of pharmacological treatment targeting these intracellular transduction pathways may prevent injury to the eye following retinal circulatory failure.
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| 7. |
- Gruter, O, et al.
(författare)
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Lentiviral vector-mediated gene transfer in adult mouse photoreceptors is impaired by the presence of a physical barrier
- 2005
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Ingår i: Gene Therapy. - : Springer Science and Business Media LLC. - 0969-7128 .- 1476-5462. ; 12:11, s. 942-947
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Tidskriftsartikel (refereegranskat)abstract
- Gene transfer offers a substantial promise for the therapy of degenerative ocular diseases. Lentiviral vectors have the ability to efficiently transduce murine photoreceptors during the first days of life, but they are poorly effective on photoreceptors during adulthood. Here, we studied whether a physical barrier was responsible for this impairment. Previous studies have described the capacity of enzymes, such as chondroitinase ABC and neuraminidase X, to modify the structure of the interphotoreceptor matrix (IPM) when subretinally injected. Considering the IPM as a physical barrier that may decrease photoreceptor transduction, we injected different enzymes into the subretinal space of the adult mouse simultaneously with the lentiviral vector preparation, to increase viral transduction by fragilizing the IPM. Subretinal injection of neuraminidase X and chondroitinase ABC induces modifications in the IPM by, respectively, revealing or decreasing peanut agglutinin sites on photoreceptors. The simultaneous subretinal injection of neuraminidase X with a lentiviral vector driving the expression of a reporter gene in the photoreceptors increases the number of transduced cells significantly ( around five-fold). After the enzyme treatment, the diffusion of the vector between the pigmented epithelium and the photoreceptors appears to facilitate the lentiviral vector transduction. Such approach targeting the IPM may help to design new strategies to improve gene delivery into the adult photoreceptors.
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| 8. |
- Johnson, Leif E., et al.
(författare)
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Retinal Adaptation to Changing Glycemic Levels in a Rat Model of Type 2 Diabetes
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Glucose concentrations are elevated in retinal cells in undiagnosed and in undertreated diabetes. Studies of diabetic patients suggest that retinal function adapts, to some extent, to this increased supply of glucose. The aim of the present study was to examine such adaptation in a model of type 2 diabetes and assess how the retina responds to the subsequent institution of glycemic control. Methods: Electroretinography (ERG) was conducted on untreated Zucker diabetic fatty (ZDF) rats and congenic controls from 8-22 weeks of age and on ZDFs treated with daily insulin from 16-22 weeks of age. Retinal sections from various ages were prepared and compared histologically and by immunocytochemistry. Principal Findings/Conclusions: Acute hyperglycemia did not have an effect on control rats while chronic hyperglycemia in the ZDF was associated with scotopic ERG amplitudes which were up to 20% higher than those of age-matched controls. This change followed the onset of hyperglycemia with a delay of over one month, supporting that habituation to hyperglycemia is a slow process. When glycemia was lowered, an immediate decrease in ZDF photoreceptoral activity was induced as seen by a reduction in a-wave amplitudes and maximum slopes of about 30%. A direct effect of insulin on the ERG was unlikely since the expression of phosphorylated Akt kinase was not affected by treatment. The electrophysiological differences between untreated ZDFs and controls preceded an activation of Muller cells in the ZDFs (up-regulation of glial fibrillary acidic protein), which was attenuated by insulin treatment. There were otherwise no signs of cell death or morphological alterations in any of the experimental groups. These data show that under chronic hyperglycemia, the ZDF retina became abnormally sensitive to variations in substrate supply. In diabetes, a similar inability to cope with intensive glucose lowering could render the retina susceptible to damage.
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| 9. |
- Moslehi, Saba, et al.
(författare)
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Comparison of fractal and grid electrodes for studying the effects of spatial confinement on dissociated retinal neuronal and glial behavior
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the impact of the geometry and material composition of electrodes on the survival and behavior of retinal cells is of importance for both fundamental cell studies and neuromodulation applications. We investigate how dissociated retinal cells from C57BL/6J mice interact with electrodes made of vertically-aligned carbon nanotubes grown on silicon dioxide substrates. We compare electrodes with different degrees of spatial confinement, specifically fractal and grid electrodes featuring connected and disconnected gaps between the electrodes, respectively. For both electrodes, we find that neuron processes predominantly accumulate on the electrode rather than the gap surfaces and that this behavior is strongest for the grid electrodes. However, the ‘closed’ character of the grid electrode gaps inhibits glia from covering the gap surfaces. This lack of glial coverage for the grids is expected to have long-term detrimental effects on neuronal survival and electrical activity. In contrast, the interconnected gaps within the fractal electrodes promote glial coverage. We describe the differing cell responses to the two electrodes and hypothesize that there is an optimal geometry that maximizes the positive response of both neurons and glia when interacting with electrodes.
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| 10. |
- Moslehi, Saba, et al.
(författare)
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Controlled assembly of retinal cells on fractal and Euclidean electrodes
- 2022
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 17:4
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Tidskriftsartikel (refereegranskat)abstract
- Controlled assembly of retinal cells on artificial surfaces is important for fundamental cell research and medical applications. We investigate fractal electrodes with branches of vertically- aligned carbon nanotubes and silicon dioxide gaps between the branches that form repeating patterns spanning from micro- to milli-meters, along with single-scaled Euclidean electrodes. Fluorescence and electron microscopy show neurons adhere in large numbers to branches while glial cells cover the gaps. This ensures neurons will be close to the electrodes' stimulating electric fields in applications. Furthermore, glia won't hinder neuronbranch interactions but will be sufficiently close for neurons to benefit from the glia's life-supporting functions. This cell 'herding' is adjusted using the fractal electrode's dimension and number of repeating levels. We explain how this tuning facilitates substantial glial coverage in the gaps which fuels neural networks with small-world structural characteristics. The large branch-gap interface then allows these networks to connect to the neuron-rich branches.
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