Impaired glucose tolerance and metabolic syndrome in idiopathic polyneuropathy: the role of pain and depression.

Chronic idiopathic axonal polyneuropathy (CIAP) is referred to as axonal neuropathy after an adequate workup fails to determine a cause. A subgroup of patients with CIAP has impaired glucose tolerance (IGT). These patients have been considered by some investigators to have a neuropathy as a result of IGT and/or metabolic syndrome (MetS). Patients with CIAP usually suffer from chronic pain and associated depression, both of which have been proposed to cause insulin resistance (IR) by such mechanisms as a sustained increase in the corticosteroids and catecholamines, and chronic low grade inflammation. In a pilot study of 14 patients with CIAP+IGT and eight normal controls, we found a correlation between the number of features of the MetS with scores of pain and depression. There was no increase in the frequency of retinopathy and nephropathy in these patients, contrary to what would have been expected if chronic hyperglycemia was the cause of the neuropathy. We hypothesize that neuropathy has an unclear cause in the majority of patients with CIAP+IGT/MetS--and IGT/MetS are a result of comorbidities of CIAP, including chronic pain and depression.

AcrySof Natural filter decreases blue light-induced apoptosis in human retinal pigment epithelium.

PURPOSE: The effect of AcrySof filter (UV light-filtering chromophore; Alcon) and AcrySof Natural filter (UV- and blue light-filtering chromophores) on blue light-induced apoptosis in human retinal pigment epithelial (RPE) cells was evaluated. DESIGN: Laboratory investigation CLINICAL RELEVANCE: Acrysof Natural filter reduces the blue-light toxicity in RPE cells and may have a positive impact on age-related macular degeneration (AMD). METHODS: RPE cells were exposed to blue light (430-450 nm) in the presence of either the AcrySof (UV only) filter or Acrysof Natural (UV and blue light) filter for 10 days. The rate of apoptosis was analyzed. RESULTS: Blue light induced significant apoptosis in RPE cells. AcrySof Natural filter significantly reduced the blue light-induced apoptosis when compared to AcrySof filter. The amount of blue-light energy reaching the cells with the AcrySof filter was 4.25 mW/cm(2) and with the AcrySof Natural filter was 2.5 mW/cm(2). CONCLUSIONS: AcrySof Natural filter significantly reduced blue light-induced apoptosis. This was most likely due to its filtering effect on blue wavelength light, which reduces the energy that reaches the cells. In patients with cataract who are at a high risk for AMD, the implantation of a blue light-filtering intraocular lens may be considered.

Time-resolved detection of melanin free radicals quenching reactive oxygen species.

Melanin, a ubiquitous, heterogeneous biological polymer composed of many different monomers, contains a population of stationary, intrinsic semiquinone-like radicals. Additional extrinsic semiquinone-like radicals are reversibly photogenerated with visible or UV irradiation. The free radical chemistry of melanin is complex and not well characterized, especially the photochemistry of melanin in the presence of oxygen. To determine directly how melanin reacts in the presence of oxygen, time-resolved electron paramagnetic resonance (TREPR) spectroscopy was used to examine melanin free radical chemistry in human retinal pigment epithelium (RPE) cells under aerobic and anaerobic conditions. A TREPR difference spectrum was used to explore the nature of melanin chemistry in the presence of oxygen. The position and symmetrical line shape of the TREPR three-dimensional difference spectrum shows that when reactive oxygen species (ROS) are scavenged, only one of the two or more chemically different melanin free radical species participates in ROS scavenging. This protective melanin radical species exists in both the extrinsic and intrinsic populations of melanin free radicals, allowing melanin to protect the RPE from toxic species in both the light and dark.

Melanin photoprotection in the human retinal pigment epithelium and its correlation with light-induced cell apoptosis.

Time-resolved electron paramagnetic resonance (TREPR) spectroscopy was used to study melanin free radicals in human retinal pigment epithelium (RPE) cells and tyrosine-derived synthetic melanin. TREPR signal traces from RPE cells reveal in vivo light-induced melanin free radical photochemistry in more detail than previously known. Electron spin polarization reflecting a non-Boltzmann population within the energy levels of the spin system is observed in RPE cells as the result of the triplet state photoproduction and subsequent disappearance of free radicals in the melanin polymer. In a set of RPE cells cultured from individual sources, differences in optical absorption, continuous wave EPR spectra, and TREPR signals were correlated with apoptosis assays performed by flow cytometry. Continuous wave EPR spectra of RPE cells and TREPR of acidified synthetic melanin suggest that increased melanin aggregation provides an increase in photoprotection in the RPE cells that are relatively less susceptible to blue light-induced apoptosis.

Near confluent laser photocoagulation for the treatment of threshold retinopathy of prematurity.

OBJECTIVE: To evaluate the effect of a near confluent pattern of indirect laser photocoagulation in reducing the rate of progression and re-treatment of threshold retinopathy of prematurity. METHODS: This study examined a noncomparative interventional case series. We performed a retrospective review of the medical records of patients who underwent peripheral laser ablation by 1 surgeon for threshold retinopathy of prematurity from 1997 to 2002. A total of 58 eyes from 31 patients were treated, and 44 eyes of 23 patients were included in the study. Ten eyes of 5 infants had zone 1 disease, and 34 eyes of 18 infants had zone 2 disease. Laser spots were placed in a near confluent pattern in the peripheral avascular retina between the ridge of extraretinal proliferation and the ora serrata. The mean +/- SD number of laser spots was 2534 +/- 455 for zone 1 (range, 2100-3378) and 1850 +/- 487 for zone 2 (range, 1030-2689). RESULTS: In 7 eyes of 4 infants with zone 1 disease, the retinopathy regressed and did not require any further treatment. Three eyes of 2 infants, however, progressed after laser treatment and required vitrectomy surgery. Progression was defined as the development of stage 4 or 5 disease. None of the patients with zone 2 disease had progression of retinopathy, and none of them needed more than 1 treatment. Patients tolerated the procedure well, and there were no complications at the time of the procedure or at follow-up visits. CONCLUSIONS: A near confluent pattern of laser photocoagulation may reduce the rate of progression of threshold retinopathy of prematurity in zone 2 (0%). The near confluent pattern of treatment may also reduce the re-treatment rate of the disease (0%). Larger studies are needed to confirm our findings.

Optical coherence tomographic findings in pregnancy-associated central serous chorioretinopathy.

PURPOSE: To report the presence and disappearance of subretinal fibrinous exudate in pregnancy-induced central serous chorioretinopathy studied with optical coherence tomography (OCT). METHODS: Case report. A 32-year-old woman was referred for ophthalmoscopic evaluation in her 32nd week of pregnancy, complaining of reduced vision in her right eye. RESULTS: The funduscopic examination revealed a serous detachment of the macula with subretinal exudative deposits in the right eye and a peripapillary serous detachment in the left eye. OCT sections through the right macula demonstrated serous elevation of the retina and the presence of highly reflective material in the subretinal space. Two weeks after delivery, OCT showed resolution of subretinal fluid and the disappearance of submacular exudate in the right eye. CONCLUSION: During pregnancy and immediately after delivery, OCT may provide information reflecting the relationship between the retina, subretinal space, and retinal pigment epithelium without any known adverse effects to the infant. In a patient with pregnancy-associated central serous chorioretinopathy, a highly reflective material, presumably fibrin, was detected spanning the subretinal space that was subsequently shown to disappear. This information may help us better understand the pathological retinal changes that may occur during pregnancy.

Trypan blue induces apoptosis in human retinal pigment epithelial cells.

PURPOSE: To examine whether trypan blue dye induces apoptosis in human retinal pigment epithelium cells. DESIGN: Laboratory investigation. METHODS: Pure cultures of human retinal pigment epithelium cells were isolated. The cells were incubated with different concentrations of trypan blue (0.5%, 0.10%, and 0.05%) for either 5 or 30 minutes. The rate of retinal pigment epithelium cell apoptosis was assessed with Annexin V-PE staining and flow cytometry. RESULTS: Trypan blue induced a statistically significant amount of apoptosis in retinal pigment epithelium cells at all the concentrations (0.5%, 0.10%, and 0.05%) (P <.05). The increase in incubation time (from 5 to 30 minutes) led to an increase in the number of apoptotic retinal pigment epithelium cells. CONCLUSION: The incubation of retinal pigment epithelium cells with trypan blue increased the number of apoptotic retinal pigment epithelium cells in vitro. Our results suggest that decisions regarding the intravitreal application of trypan blue dye need to be made with caution.

Indocyanine green induces apoptosis in human retinal pigment epithelial cells.

PURPOSE: To examine whether indocyanine green (ICG) dye induces apoptosis in human retinal pigment epithelial (RPE) cells. DESIGN: Laboratory investigation. METHODS: Pure cultures of human RPE cells were isolated. Retinal pigment epithelial cells were incubated with different concentrations of ICG dye (1 mg/ml, 5 mg/ml, or 20 mg/ml) for 30 minutes. The rate of RPE cell apoptosis was assessed with Annexin V-FITC staining and propidium iodide (PI) by flow cytometry. RESULTS: Retinal pigment epithelial cells maintained their monolayer morphology after incubation with ICG dye. However, ICG induced a statistically significant amount of apoptosis in RPE cells at all the concentrations (1 mg/ml, 5 mg/ml, and 20 mg/ml) after 30 minutes of incubation (P <.05). The solvent solution alone (without the ICG dye) did not induce any significant apoptosis in RPE cells, when compared with culture medium. CONCLUSIONS: The incubation of RPE cells with ICG dye increased the number of apoptotic RPE cells in vitro. Our findings indicate that the decision over the intravitreal application of ICG dye needs to be made with caution.

Derivation and comparative assessment of retinal pigment epithelium from human embryonic stem cells using transcriptomics.

Human stem-cell derivatives are likely to play an important role in the future of regenerative medicine. Evaluation and comparison to their in vivo counterparts is critical for assessment of their therapeutic potential. Transcriptomics was used to compare a new differentiation derivative of human embryonic stem (hES) cells--retinal pigment epithelium (RPE)--to human fetal RPE. Several hES cell lines were differentiated into putative RPE, which expressed RPEspecific molecular markers and was capable of phagocytosis, an important RPE function. Isolated hES cell-derived RPE was able to transdifferentiate into cells of neuronal lineage and redifferentiate into RPE-like cells through multiple passages (>30 Population doublings). Gene expression profiling demonstrated their higher similarity to primary RPE tissue than of existing human RPE cell lines D407 and ARPE-19, which has been shown to attenuate loss of visual function in animals. This is the first report of the isolation and characterization of putative RPE cells from hES cells, as well as the first application of transcriptomics to assess embryonic stem-cell derivatives and their in vivo counterparts--a "differentiomics" outlook. We describe for the first time, a differentiation system that does not require coculture with animal cells or factors, thus allowing the production of zoonoses-free RPE cells suitable for subretinal transplantation in patients with retinal degenerative diseases. With the further development of therapeutic cloning, or the creation of the banks of homozygous human leucocyte antigen (HLA) hES cells using parthenogenesis, RPE lines could be generated to overcome the problem of immune rejection and could be one of the nearest term applications of stem-cell technology.

The effect of type I and II interferons on human fetal retinal pigment epithelium-induced apoptosis in Jurkat T cells.

PURPOSE: To examine the regulatory effects of interferon (IFN)-alpha, IFN-gamma, transforming growth factor (TGF)-beta, and tumor necrosis factor (TNF)-alpha on human fetal retinal pigment epithelial (HFRPE) cell-induced apoptosis of human Jurkat T (Jkt) cells. METHODS: Pure cultures of HFRPE cells were isolated. The cells were precultured with medium alone or with addition of IFN-alpha, IFN-gamma, TNF-alpha, or TGF-beta for 72 hours. Thereafter, HFRPE cells were extensively washed before they were cocultured jointly with Jkt cells (standard) or cultured alone for another 48 hours to accumulate conditioned medium that is collected and added as cell-free conditioned medium to Jkt cell cultures (supernatant). Jkt cells were cocultured under the two culture conditions for 48, 72, and 96 hours. The rate of apoptosis in Jkt T cells was determined with annexin V staining and flow cytometry. RESULTS: Both IFN-alpha and -gamma upregulated HFRPE-induced apoptosis in Jkt T cells. However, the apoptosis induced by IFN-alpha-activated HFRPE cells was significant only in the absence of cell-cell contact (supernatant). The supernatant induced a higher rate of apoptosis in Jkt T cells when compared to the direct coculture of the cells. TGF-beta and TNF-alpha did not upregulate HFRPE-induced apoptosis in Jkt T cells. CONCLUSIONS: These results indicate that type I and type II IFNs can upregulated HFRPE-induced apoptosis in Jkt T cells, IFN-gamma being the more effective cytokine. Neither, TGF-beta nor TNF-alpha upregulated the HFRPE-induced apoptosis in Jkt T cells. Although HFRPE-induced apoptosis was mediated in a cell-cell-contact-independent pathway, HFRPE cells may also express membrane-bound antiapoptotic molecules. These findings may help us to understand better the modulatory effects of pro- and anti-inflammatory cytokines on immune suppressive characteristics of RPE cells.

Human fetal retinal pigment epithelium induces apoptosis in human T-cell line Jurkat which is independent from its expression of TRAIL.

PURPOSE: To evaluate whether human fetal retinal pigment epithelial (HFRPE) cells express TRAIL (tumor necrosis factor related apoptosis inducing ligand). The role of TRAIL in HFRPE induced apoptosis was evaluated. METHODS: Pure cultures of HFRPE cells were isolated. The expression of TRAIL protein and mRNA in non-activated and IFN-gamma activated HFRPE cells was evaluated with RT-PCR. The role of TRAIL in HFRPE induced apoptosis was assessed by incubating HFRPE cells with human T-cell leukemia line Jurkat (Jkt) in the presence or absence of neutralizing TRAIL antibodies. Cultures were pulsed with [(3)H]-thymidine to measure Jkt cell proliferation. The role of TRAIL was further examined by western blott evaluating the cleavage of caspases 8 and 10 in Jkt cells after their incubation with HFRPE cells. RESULTS: HFRPE cells expressed TRAIL mRNA. The expression of TRAIL mRNA and protein was up-regulated by IFN-gamma activation. However, anti-TRAIL antibodies were not able to prevent the HFRPE induced suppression of Jkt cell proliferation. The caspases 8 and 10 were also not cleaved in Jkt cells after their incubation with IFN-gamma activated HFRPE cells. CONCLUSIONS: Although HFRPE cells express TRAIL and its expression is upregulated by IFN-gamma activation, TRAIL is not involved in HFRPE induced apoptosis in Jkt cells. Currently the role of TRAIL in HFRPE cells is under investigation.

Rheumatoid hyperviscosity syndrome: reversibility of microvascular abnormalities after treatment.

PURPOSE: To report a case of rheumatoid hyperviscosity syndrome involving both retinal and choroidal circulation that resolved after treatment. DESIGN: Interventional case report. METHODS: A 58-year-old woman with clinical and serologic evidence of an inflammatory connective tissue disease without any visual complaints was referred for a funduscopic evaluation. RESULTS: Funduscopic examination revealed marked dilation and beading of the venous system, microaneurysms, and telangiectatic capillary beds in the posterior pole. Fluorescein angiography disclosed delayed choroidal filling, prolonged arteriovenous transit time, and areas of capillary nonperfusion. These findings were accompanied by a severe polyclonal hypergammaglobulinemia and a 10-fold increase in serum viscosity. The ocular findings were reversible after plasmapheresis and steroid treatment. CONCLUSION: Rheumatoid hyperviscosity syndrome can involve both retinal and choroidal circulation. The prominent microvasculopathy is reversible after appropriate treatment.