The prevalence of activated protein C (APC) resistance and factor V Leiden is significantly higher in patients with retinal vein occlusion without general risk factors. Case-control study and meta-analysis.

Several small case-control studies have investigated whether factor V Leiden (FVL) is a risk factor for retinal vein occlusion (RVO) and generated conflicting data. To clarify this question we performed a large two-centre case-control study and a meta-analysis of published studies. Two hundred seven consecutive patients with RVO and a control group of 150 subjects were screened between 1996 and 2006.

Signaling pathways involved in PDGF-evoked cellular responses in human RPE cells.

We examined whether PDGF may directly stimulate the expression of VEGF by retinal pigment epithelial (RPE) cells in vitro, and the involvement of three signal transduction pathways in the regulation of PDGF-evoked cell proliferation, migration, and production of VEGF-A was investigated. PDGF stimulated the gene and protein expression of VEGF-A by RPE cells, and increased cell proliferation and chemotaxis. PDGF activated all signaling pathways investigated, as determined by increased phosphorylation levels of ERK1/2, p38, and Akt proteins.

Glial cell-mediated spread of retinal degeneration during detachment: a hypothesis based upon studies in rabbits.

In human subjects with peripheral retinal detachments, visual deficits are not restricted to the detached retina but are also present in the non-detached tissue. Based upon studies on a rabbit model of rhegmatogenous retinal detachment, we propose a glial cell-mediated mechanism of spread of retinal degeneration into non-detached retinal areas which may also have importance for the understanding of alterations in the human retina. Both detached and attached portions of the rabbit retina display photoreceptor cell degeneration and cystic degeneration of the innermost layers.

[Factor VIII activity in patients with central retinal vein occlusion in comparison to patients with a history of pelvic and lower limb venous thrombosis and a healthy control group].

Background: High factor VIII activity levels increase the risk of venous thromboembolism. This study was carried out to investigate the association between factor VIII activity and central retinal vein occlusion (CRVO) in comparison to patients with a history of venous thrombosis and a healthy control group.

Patients And Methods: We examined the factor VIII activity in 62 patients with CRVO, 67 patients with venous thrombosis and 107 healthy individuals.

Vitreoretinal endoscope for the assessment of the peripheral retina and the ciliary body after large retinectomies in severe anterior PVR.

Purpose: We evaluated endoscopically the changes of the peripheral retina and the ciliary body after large retinectomies.

Methods: The peripheral retina and the ciliary body of 5 patients with anterior proliferative vitreoretinopathy after large retinectomies (> 180 degrees) were visualized endoscopically.

Results: The endoscope allowed a complete assessment of the peripheral retina and the ciliary body.

GABA(A) receptors in Müller glial cells of the human retina.

The present study was aimed at characterizing the GABA(A) receptor-mediated currents in acutely isolated glial (Müller) cells of the human retina and investigating their subcellular localization across the Müller cell membrane. Extracellular application of GABA evoked two current responses in human Müller cells: a fast transient GABA(A) receptor-mediated current that inactivated within 10 s and that was independent of extracellular Na(+), and a sustained current that was dependent on extracellular Na(+) and that was mediated by high-affinity GABA transporters. The receptor current was half-maximally activated at a GABA concentration of 32 microM, while the transporter current showed an affinity constant of 7.

Recovery from hepatic retinopathy after liver transplantation.

Background: In chronic liver disease the neuroglial cells may be affected by neurotoxic metabolites which, in turn, could be expected to affect neuronal functions. The aim of this study was to evaluate the electroretinograms (ERG) from patients before and after liver transplantation, in order to study possible functional changes of the retina.

Methods: Twelve patients with liver cirrhosis underwent routine ophthalmological examination and ERG before and after successful liver transplantation.

Elevated proto-oncogene and collagen mRNA expression in PVR retinas.

Purpose: Retinal detachment is often accompanied by proliferation and migration of retinal cells and by increased synthesis of structural proteins, known as proliferative vitreoretinopathy (PVR). Herein we investigate the messenger RNA (mRNA) expression of proto-oncogenes responsible for cell proliferation and of structural proteins that have a role in membrane formation.

Methods: Retinal samples were obtained from patients undergoing vitreoretinal surgery for the treatment of retinal detachment complicated by PVR.

Experimental retinal detachment causes widespread and multilayered degeneration in rabbit retina.

Retinal detachment remains one of the most frequent causes of visual impairment in humans, even after ophthalmoscopically successful retinal reattachment. This study was aimed at monitoring (ultra-) structural alterations of retinae of rabbits after experimental detachment. A surgical procedure was used to produce local retinal detachments in rabbit eyes similar to the typical lesions in human patients.

Determination of the solubility of perfluorocarbon liquids in silicone oil in vitro and in vivo.

Purpose: To investigate the solubility of perfluorocarbon liquids (PFCL) in silicone oil.

Methods: Forty-eight samples of silicone oil (1,300 mPas, n = 22; 5,000 mPas, n = 26) were analyzed for dissolved fluorocarbon molecules after surgical removal from patients who had initially undergone vitreoretinal surgery with (n = 41) and as control without (n = 7) the use of perfluorodecalin in headspace gas chromatography. In vitro, the solubility of three different PFCL-perfluorooctane (PFO), perfluorodecalin (PFD), and fluoromethylcyclohexane (FMCH)-in silicone oil of various viscosities was determined.

Upregulation of extracellular ATP-induced Müller cell responses in a dispase model of proliferative vitreoretinopathy.

Purpose: To test whether in an animal model of proliferative vitreoretinopathy (PVR) the Müller glial cells displayed an upregulation of purinergic P2 receptor-mediated responses.

Methods: PVR was induced by intravitreal injection of the proteolytic enzyme, dispase, in the eyes of adult rabbits. The developing PVR was examined ophthalmoscopically.

Arachidonic acid-induced inhibition of Ca2+ channel currents in retinal glial (Müller) cells.

Background: Arachidonic acid is a second messenger that has been implicated in several pathological conditions in nervous tissues. The present study was carried out to determine whether the second messenger arachidonic acid modulates currents through voltage-gated Ca2+ channels in freshly isolated Müller glial cells.

Methods: Whole-cell voltage-clamp recordings were made in human Muller cells to investigate Ba2+ and Na+ currents through high-voltage-activated (HVA) channels, and in rabbit Muller cells to study Na+ currents through low-voltage-activated (LVA) channels.

Retinal pigment epithelium melanin granules are phagocytozed by Müller glial cells in experimental retinal detachment.

The ability of retinal Müller glial cells to perform phagocytosis in vivo is studied in a rabbit model of experimental retinal detachment where pigment epithelial cells are occasionally detached together with the neural retina. While macrophages and/or microglial cells phagocytoze most of the cellular debris at the sclerad surface of the detached retinae, some Müller cells accumulate melanin granules. The granules are virtually intact at the ultrastructural level, and are surrounded by a membrane.

Facilitation of artificial retinal detachment for macular translocation surgery tested in rabbit.

Purpose: For macular translocation surgery, the native attached retina has to be detached either locally or completely. Although different surgical techniques are used, there is a general search for supporting procedures that facilitate and accelerate the retinal detachment.

Methods: Pars plana vitrectomies were performed in pigmented rabbits.

Electrophysiology of rabbit Müller (glial) cells in experimental retinal detachment and PVR.

Purpose: To determine the electrophysiological properties of Müller (glial) cells from experimentally detached rabbit retinas.

Methods: A stable local retinal detachment was induced by subretinal injection of a sodium hyaluronate solution. Müller cells were acutely dissociated and studied by the whole-cell voltage-clamp technique.

Upregulation of P2X(7) receptor currents in Müller glial cells during proliferative vitreoretinopathy.

Purpose: Müller glial cells from the human retina express purinergic P2X(7) receptors. Because extracellular adenosine triphosphate (ATP) is assumed to be a mediator of the induction or maintenance of gliosis, this study was undertaken to determine whether the expression of these receptors is different in human Müller cells obtained from retinas of healthy donors and of patients with choroidal melanoma and proliferative vitreoretinopathy (PVR).

Methods: Human Müller cells were enzymatically isolated from donor retinas, and whole-cell patch-clamp recordings were made to characterize the density of the P2X(7) currents and the activation of currents through Ca2+-activated K+ channels of big conductance (I:(BK)) that reflects the increase of the intracellular Ca2+ concentration.

Farnesol modulates membrane currents in human retinal glial cells.

Farnesol, a C(15) natural isoprenoid, exerts complex modulating effects on the membrane permeability of human retinal glial (Müller) cells. Several glial cationic currents were examined. At low micromolar concentrations, farnesol reduced the amplitudes of all fast and depolarization-activated membrane currents expressed by Müller cells, that is, currents through 1) transient low-voltage-activated (LVA; IC(50) = 2.

The local and systemic secretion of the pro-inflammatory cytokine interleukin-6 after transplantation of retinal pigment epithelium cells in a rabbit model.

The rejection of retinal pigment epithelium (RPE) allografts is one of the major problems for long-term success after retinal transplantation. However, the details of the immunological interactions in the subretinal space after transplantation are still unknown. The aim of our study was to investigate the role of IL-6 in the rejection process in the subretinal space and to use IL-6 monitoring for a possible early sign of rejection after transplantation of allogeneic RPE cells.

R-(+)-verapamil, S-(-)-verapamil, and racemic verapamil inhibit human retinal pigment epithelial cell contraction.

Purpose: To evaluate the effects of R-(+)-verapamil, S-(-)-verapamil, and the racemate on in vitro contraction of human retinal pigment epithelial cells.

Methods: RPE cells from human donor eyes were enzymatically dissociated and cultured on collagen gels. Transdifferentiated RPE cells (seventh and eighth passage) were used for experiments.

Age- and disease-related changes of calcium channel-mediated currents in human Müller glial cells.

Purpose: To determine whether the expression of voltage-gated Ca2+ channels in human Müller glial cells changes during normal aging and in cells from patients with proliferative vitreoretinopathy (PVR).

Methods: Müller cells were enzymatically isolated from retinas of healthy donors and from excised retinal pieces of patients with PVR, and the whole-cell, voltage-clamp technique was used to characterize the current densities of transient, low-voltage-activated calcium channels and of sustained. high-voltage-activated calcium channels, respectively.

P2X7 receptors in Müller glial cells from the human retina.

ATP has been shown to be an important extracellular signaling molecule. There are two subgroups of receptors for ATP (and other purines and pyrimidines): the ionotropic P2X and the G-protein-coupled P2Y receptors. Different subtypes of these receptors have been identified by molecular biology, but little is known about their functional properties in the nervous system.