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Biermann J.,Albert Ludwigs University of Freiburg | Grieshaber P.,Albert Ludwigs University of Freiburg | Goebel U.,University Hospital Freiburg | Martin G.,Albert Ludwigs University of Freiburg | And 3 more authors.
Investigative Ophthalmology and Visual Science | Year: 2010

PURPOSE. Valproic acid (VPA) has been demonstrated to have neuroprotective effects in neurodegenerative conditions. VPA inhibits histone-deacetylases (HDAC) and delays apoptosis in degenerating neurons. The authors investigated whether VPA delays retinal ganglion cell (RGC) death and enhances axonal regeneration after optic nerve crush (ONC). Furthermore, potential molecular targets involved in VPA-mediated protection were analyzed. METHODS. ONC was performed on the left eye of rats, which received VPA or Ringer's solution subcutaneously (SC; 300 mg/kg twice daily) or intravitreally (single postlesional injection). Densities of fluorogold-labeled RGC were analyzed in retinal flatmounts after 5 or 8 days. Retinal tissue was also harvested and processed to quantify axon growth in retinal explants; evaluate caspase-3 activity; analyze transcription factor cAMP response element binding protein (CREB); and determine acetylated histone 3 and 4, as well as phosphorylated extracellular signal-regulated kinase (pERK) 1/2. RESULTS. Five and 8 days after ONC, 93% and 58% RGC survived after subcutaneous VPA treatment in comparison to Ringer's solution (62% and 37% viable RGC), respectively (P < 0.001). Likewise, a single intravitreal injection of VPA immediately after injury significantly delayed apoptosis in RGC (P = 0.0016). Injured RGC treated with VPA showed better regeneration of their axons in culture (196 axons/explant) than the crushed controls receiving Ringer (115 axons/explant). RGC axons of the right control eyes regenerated more after VPA treatment. VPA-mediated neuroprotection and neuroregeneration were accompanied by decreased caspase-3 activity, CREB induction, pERK1/2 activation, but not by altered histoneacetylation. CONCLUSIONS. VPA provided neuroprotection and axonal regrowth after ONC. Alterations were observed in several pathways; however, the precise mechanism of VPA-mediated protection is not yet fully understood. © Association for Research in Vision and Ophthalmology.

Prokosch V.,University Eye Hospital Muenster | Chiwitt C.,University Eye Hospital Muenster | Rose K.,University Eye Hospital Muenster | Thanos S.,University Eye Hospital Muenster
Expert Review of Proteomics | Year: 2010

Neurons of the mammalian CNS, including retinal ganglion cells, lack, in contrast to the PNS, the ability to regenerate axons spontaneously after injury. Regeneration of the CNS is extremely complex and involves various molecular factors and cells. Therewith the regenerative process remains an enormous scientific and clinical challenge. This article provides an overview of proteins that play a crucial role in axon regeneration of retinal ganglion cells and their underlying signaling pathways. In this context, we elucidate the role of 2D gel electrophoresis and highlight some additional proteins, altered upon regeneration by using this highly sensitive method. © 2010 Expert Reviews Ltd.

Prokosch V.,University Eye Hospital Muenster | Prokosch V.,University of Munster | Prokosch J.-E.,University Eye Hospital Muenster | Promesberger J.,University Eye Hospital Muenster | And 4 more authors.
Current Eye Research | Year: 2014

Purpose: (1) To determine the current bacteriological spectrum in connatal and acquired lacrimal duct obstruction (cLDO and aLDO, respectively) and (2) to analyze the antimicrobial susceptibility patterns of the recovered isolates. Materials and Methods: In a prospective study, 463 samples (30% bilateral LDO) were obtained from the lacrimal ducts of 132 infants and 192 adult patients with symptomatic LDO between 2007 and 2012 at a tertiary eye-care center. The samples were cultured for aerobic and anaerobic bacteria, which were subsequently identified using standard microbiological techniques. Antimicrobial susceptibility testing was performed for each isolate using the disk diffusion method. Data were analyzed using SPSS and chi-square test for significance testing. Results: (1) Among 463 samples investigated, 333 samples were positive, i.e. at least one bacterial isolate was recovered. A total of 72% were recovered (97% of samples from children and 56% of samples from adults), yielding a total of 654 bacterial isolates. Co-colonization with up to five different bacterial species was observed in a large proportion of the samples from children (87%), but in only 20% of those from adults and with a maximum of three different bacteria. Gram-positive bacteria were identified in 72% of the positive samples in both aLDO and cLDO. The most common Gram-positive species in cLDO was Streptococcus pneumoniae (29%), while that in cLDO was Staphylococcus aureus (60%). The most prevalent Gram-negative species were Moraxella catarrhalis (8%) and Haemophilus influenzae (9%) in cLDO and Pseudomonas aeruginosa in aLDO (12%). (2) Susceptibility testing revealed chloramphenicol to be the most active antibiotic with resistance rates of 3% in cLDO and 6% in aLDO, followed by ciprofloxacin (1% and 6%). Erythromycin and gentamicin were the least active of all, with resistances of 41% and 22%, respectively, in cLDO, and 23% and 11% in aLDO. Conclusions: Bacterial colonization occurs regularly in LDO, with Gram-positive bacteria being found in 97% of cLDO samples and 56% of aLDO samples. A remarkable number of different species were found to co-colonize in cLDO. The most common bacteria in LDO are highly susceptible in vitro to chloramphenicol and ciprofloxacin. © 2014 Informa Healthcare USA, Inc. All rights reserved.

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