Szilard Kiss

Dehydroascorbic acid, a blood–brain barrier transportable form of vitamin C, mediates potent cerebroprotection in experimental stroke

Neuronal injury in ischemic stroke is partly mediated by cytotoxic reactive oxygen species. Although the antioxidant ascorbic acid (AA) or vitamin C does not penetrate the blood–brain barrier (BBB), its oxidized form, dehydroascorbic acid (DHA), enters the brain by means of facilitative transport. We hypothesized that i.v. DHA would improve outcome after stroke because of its ability to cross the BBB and augment brain antioxidant levels. Reversible or permanent focal cerebral ischemia was created by intraluminal middle cerebral artery occlusion in mice treated with vehicle, AA, or DHA (40, 250, or 500 mg/kg), either before or after ischemia. Given before ischemia, DHA caused dose-dependent increases in postreperfusion cerebral blood flow, with reductions in neurological deficit and mortality. In reperfused cerebral ischemia, mean infarct volume was reduced from 53% and 59% in vehicle- and AA-treated animals, respectively, to 15% in 250 mg/kg DHA-treated animals (P < 0.05). Similar significant reductions occurred in nonreperfused cerebral ischemia. Delayed postischemic DHA administration after 15 min or 3 h also mediated improved outcomes. DHA (250 mg/kg or 500 mg/kg) administered at 3 h postischemia reduced infarct volume by 6- to 9-fold, to only 5% with the highest DHA dose (P < 0.05). In contrast, AA had no effect on infarct volumes, mortality, or neurological deficits. No differences in the incidence of intracerebral hemorrhage occurred. Unlike exogenous AA, DHA confers in vivo, dose-dependent neuroprotection in reperfused and nonreperfused cerebral ischemia at clinically relevant times. As a naturally occurring interconvertible form of AA with BBB permeability, DHA represents a promising pharmacological therapy for stroke based on its effects in this model of cerebral ischemia.

Ultra-wide-field angiography improves the detection and classification of diabetic retinopathy.

Purpose: To evaluate patients with diabetic retinopathy using ultra–wide-field fluorescein angiography and to compare the visualized retinal pathology with that seen on an overly of conventional 7 standard field (7SF) imaging. Methods: Two hundred and eighteen eyes of 118 diabetic patients who underwent diagnostic fluorescein angiography using the Optos Optomap Panoramic 200A imaging system were included. The visualized area of the retina, retinal nonperfusion, retinal neovascularization, and panretinal photocoagulation were quantified by two independent masked graders. The respective areas identified on the ultra–wide-field fluorescein angiography image were compared with an overly of a modified 7SF image as outlined in the Early Treatment Diabetic Retinopathy Study. Results: Ultra–wide-field fluorescein angiograms imaging, on average, demonstrated 3.2 times more total retinal surface area than 7SF. When compared with 7SF, ultra–wide-field fluorescein angiography showed 3.9 times more nonperfusion (P < 0.001), 1.9 times more neovascularization (P = 0.036), and 3.8 times more panretinal photocoagulation (P < 0.001). In 22 eyes (10%), ultra–wide-field fluorescein angiography demonstrated retinal pathology (including nonperfusion and neovascularization) not evident in an 7SF overly. Conclusion: Compared with conventional 7SF imaging, ultra–wide-field fluorescein angiography reveals significantly more retinal vascular pathology in patients with diabetic retinopathy. Improved retinal visualization may alter the classification of diabetic retinopathy and may therefore influence follow-up and treatment of these patients.

Ocular Manifestations and Treatment of Syphilis

Syphilis is a sexually transmitted, chronic, systemic infection caused by the spirochete Treponema pallidum. If left untreated, the disease progresses through four stages, with the potential to cause significant morbidity to any major organ of the body. Frequent syphilitic ocular manifestations, which can occur at any stage of the disease, include interstitial keratitis, anterior, intermediate, and posterior uveitis, chorioretinitis, retinitis, retinal vasculitis and cranial nerve and optic neuropathies. Diagnosis is centered around a high level of clinical suspicion and includes treponemal specific and non-treponemal serologic tests. All patients with newly diagnosed syphilis should be tested for co-infection with human immunodeficiency virus, as the risk factors are similar for both diseases. Additionally, all patients with ocular syphilis should be tested for neurosyphilis. The preferred treatment for all stages of syphilis remains parenteral penicillin G. With proper diagnosis and prompt antibiotic treatment, the majority of cases of syphilis can result in a cure.

Postischemic cerebrovascular E-selectin expression mediates tissue injury in murine stroke.

Background and Purpose Although the deleterious role of several proinflammatory mediators, including P-selectin, in reperfused stroke is well established, the role of E-selectin has not been fully characterized. Methods E-selectin mRNA expression was studied at 4, 10, and 24 hours after reperfusion with reverse transcription and polymerase chain reaction in mice (n=18) subjected to transient intraluminal middle cerebral artery occlusion (MCAO). Mice received intravenous injection with anti–E-selectin monoclonal antibody (10, 35, or 50 &mgr;g), nonimmune IgG, or vehicle immediately before MCAO and 90 minutes later (n=85). Others received anti–E-selectin antibody 3 or 6 hours after MCAO (n=32). Myeloperoxidase activity was measured in sham-operated mice and after 10 hours of reperfusion in saline-, nonimmune IgG–, or anti–E-selectin IgG–treated cohorts (n=17). Serial cerebral blood flow was measured with laser-Doppler flowmetry, and outcomes were assessed by neurological deficits and infarct volumes with the use of planimetric analysis of triphenyltetrazolium chloride–stained sections. Results Upregulated E-selectin expression occurred in the ischemic cerebral vasculature within 4 hours of reperfusion and persisted for 24 hours. Anti–E-selectin antibody increased ischemic cortical cerebral blood flow up to 2.6-fold (P <0.05). In addition to dose-dependent reductions in neurological deficits (P <0.05), mortality, and infarct volumes (P <0.01 for 35 and 50 &mgr;g), anti–E-selectin treatment reduced cerebral neutrophil accumulation (P <0.05) and was neuroprotective even if delayed until 3 hours after ischemia (P <0.05). Conclusions These findings establish a functional role for E-selectin in the pathogenesis of tissue injury after cerebral ischemia and reperfusion and suggest that E-selectin blockade may be clinically useful in the treatment of reperfused stroke.

Vogt-Koyanagi-Harada Disease

Vogt-Koyanagi-Harada disease (VKH) is a multisystem autoimmune disorder principally affecting pigmented tissues in the ocular, auditory, integumentary and central nervous systems. Patients are typically 20 to 50 years old and have no history of either surgical or accidental ocular trauma. Pigmented races are more commonly affected. Depending on revised diagnostic criteria, the disease is classified as complete, incomplete or probable based on the presence of extraocular findings (neurological, auditory and integumentary). The clinical course of VKH is divided into four phases: prodromal (mimics a viral infection), uveitic (bilateral diffuse uveitis with papillitis and exudative retinal detachment), convalescent (tissue depigmentation), and chronic recurrent (recurrent uveitis and ocular complications). The pathogenesis of VKH is thought to be related to an aberrant T cell-mediated immune response directed against self-antigens found on melanocytes. VKH has been linked to human leukocyte antigen DR4 (HLA-DR4) and HLA-Dw53, with strongest associated risk for HLA-DRB1*0405 haplotype. The diagnosis of VKH is clinical, and differential includes sympathetic ophthalmia, sarcoidosis, primary intraocular B-cell lymphoma, posterior scleritis, and uveal effusion syndrome. Treatment is typically initiated with high-dose oral corticosteroids, but other immunomondulatory agents (most oftentimes cyclosporine) may be needed for non-responsive patients or when corticosteroid side-effects are not tolerated. Visual prognosis is generally good with prompt diagnosis and aggressive immunomodulatory treatment.

Detection of retinal changes in Parkinson's disease with spectral-domain optical coherence tomography

Purpose This pilot study investigated whether high-resolution spectral-domain optical coherence tomography (SD-OCT) could detect differences in inner retinal layer (IRL), peripapillary retinal nerve fiber layer (RNFL), and macular thickness between patients with Parkinson’s disease (PD) and controls. Methods Both eyes of patients with PD and age-matched controls were imaged with the Heidelberg Spectralis® HRA + OCT. RNFL, IRL, and macular thickness were measured for each eye using Heidelberg software. These measurements were compared with validated, published normal values for macular and RNFL thickness, and compared with matched controls for IRL thickness. Results Eighteen eyes from nine subjects with PD and 19 eyes of 16 control subjects were evaluated using SD-OCT. The average age of PD patients was 64 years with a range of 52–75 years. The average age of controls was 67 years with a range of 50–81 years. No significant reduction in IRL thickness was detected between PD patients and age-matched controls at 13 points along a 6 mm horizontal section through the fovea. No significant difference in RNFL thickness was detected between PD patients and published normal values. Overall average RNFL thickness was 97 μm for PD patients, which exactly matched the normative database value. However, significant differences in macular thickness were detected in three of nine subfields between PD subjects and published normal values. In PD subjects, the outer superior subfield was 2.8% thinner (P = 0.026), while the outer nasal and inner inferior subfields were 2.8% (P = 0.016) and 2.7% (P = 0.001) thicker compared to published normal values. Conclusion In this pilot study, significant differences in macular thickness were detected in three of nine subfields by SD-OCT. However, SD-OCT did not detect significant reductions in peripapillary RNFL and IRL thickness between PD patients and controls. This suggests that macular thickness measurements by SD-OCT may potentially be used as an objective, noninvasive, and easily quantifiable in vivo biomarker in PD. Larger, longitudinal studies are needed to explore these relationships further.

Inhibition of choroidal neovascularization in a nonhuman primate model by intravitreal administration of an AAV2 vector expressing a novel anti-VEGF molecule.

Inhibition of vascular endothelial growth factor (VEGF) for the management of the pathological ocular neovascularization associated with diseases such as neovascular age-related macular degeneration is a proven paradigm; however, monthly intravitreal injections are required for optimal treatment. We have previously shown that a novel, secreted anti-VEGF molecule sFLT01 delivered by intravitreal injection of an AAV2 vector (AAV2-sFLT01) gives persistent expression and is efficacious in a murine model of retinal neovascularization. In the present study, we investigate transduction and efficacy of an intravitreally administered AAV2-sFLT01 in a nonhuman primate (NHP) model of choroidal neovascularization (CNV). A dose-dependent and persistent expression of sFLT01 was observed by collecting samples of aqueous humor at different time points over 5 months. The location of transduction as elucidated by in situ hybridization was in the transitional epithelial cells of the pars plana and in retinal ganglion cells. AAV2-sFLT01 was able to effectively inhibit laser-induced CNV in a dose-dependent manner as determined by comparing the number of leaking CNV lesions in the treated versus control eyes using fluorescein angiography. Our data suggest that intravitreal delivery of AAV2-sFLT01 may be an effective long-term treatment for diseases caused by ocular neovascularization.

Wide-field Imaging of the Retina

The retinal periphery is the site of pathology in several eye diseases. Imaging of the peripheral retina offers a way to diagnose, monitor, and evaluate responses to the treatment of these conditions. Traditional fundus cameras have offered a 30- to 50-degree field of view. Recent technology has advanced to provide up to a 200-degree field of view. The utility of this technology in clinical practice continues to be investigated; wide-field color photography, autofluorescence imaging, and fluorescein angiography have been used for imaging peripheral retinal disease. Due to the limitations of this imaging technology and the lack of normative data, however, the clinical role of wide-field imaging remains controversial.

Neuroprotection in cerebral ischemia by neutralization of 3-aminopropanal

Cerebral ischemia stimulates increased activity of polyamine oxidase, a ubiquitous enzyme that catabolizes polyamines to produce 3-aminopropanal. 3-Aminopropanal is a reactive aldehyde that mediates progressive neuronal necrosis and glial apoptosis. Here we report that increased levels of 3-aminopropanal-modified protein levels in humans after aneurysmal subarachnoid hemorrhage correlate with the degree of cerebral injury as measured by admission Hunt/Hess grade. In vitro screening of clinically approved drugs reveals that N-2-mercaptopropionyl glycine (N-2-MPG), an agent clinically approved for prevention of renal stones in patients with cysteinuria, significantly inhibits the cytotoxicity of 3-aminopropanal. N-2-MPG reacts with 3-aminopropanal to yield a nontoxic thioacetal adduct, as confirmed by electrospray ionization mass spectroscopy. Administration of N-2-MPG in clinically relevant doses to rats significantly reduces cerebral 3-aminopropanal-modified protein immunoreactivity and infarct volume in a standardized model of middle cerebral artery occlusion, even when the agent is administered after the onset of ischemia. These results implicate 3-aminopropanal as a therapeutic target for cerebral ischemia.

Comparison of ultra-widefield fluorescein angiography with the Heidelberg Spectralis® noncontact ultra-widefield module versus the Optos® Optomap®

Purpose To compare ultra-widefield fluorescein angiography imaging using the Optos® Optomap® and the Heidelberg Spectralis® noncontact ultra-widefield module. Methods Five patients (ten eyes) underwent ultra-widefield fluorescein angiography using the Optos® panoramic P200Tx imaging system and the noncontact ultra-widefield module in the Heidelberg Spectralis® HRA+OCT system. The images were obtained as a single, nonsteered shot centered on the macula. The area of imaged retina was outlined and quantified using Adobe® Photoshop® C5 software. The total area and area within each of four visualized quadrants was calculated and compared between the two imaging modalities. Three masked reviewers also evaluated each quadrant per eye (40 total quadrants) to determine which modality imaged the retinal vasculature most peripherally. Results Optos® imaging captured a total retinal area averaging 151,362 pixels, ranging from 116,998 to 205,833 pixels, while the area captured using the Heidelberg Spectralis® was 101,786 pixels, ranging from 73,424 to 116,319 (P = 0.0002). The average area per individual quadrant imaged by Optos® versus the Heidelberg Spectralis® superiorly was 32,373 vs 32,789 pixels, respectively (P = 0.91), inferiorly was 24,665 vs 26,117 pixels, respectively (P = 0.71), temporally was 47,948 vs 20,645 pixels, respectively (P = 0.0001), and nasally was 46,374 vs 22,234 pixels, respectively (P = 0.0001). The Heidelberg Spectralis® was able to image the superior and inferior retinal vasculature to a more distal point than was the Optos®, in nine of ten eyes (18 of 20 quadrants). The Optos® was able to image the nasal and temporal retinal vasculature to a more distal point than was the Heidelberg Spectralis®, in ten of ten eyes (20 of 20 quadrants). Conclusion The ultra-widefield fluorescein angiography obtained with the Optos® and Heidelberg Spectralis® ultra-widefield imaging systems are both excellent modalities that provide views of the peripheral retina. On a single nonsteered image, the Optos® Optomap® covered a significantly larger total retinal surface area, with greater image variability, than did the Heidelberg Spectralis® ultra-widefield module. The Optos® captured an appreciably wider view of the retina temporally and nasally, albeit with peripheral distortion, while the ultra-widefield Heidelberg Spectralis® module was able to image the superior and inferior retinal vasculature more peripherally. The clinical significance of these findings as well as the area imaged on steered montaged images remains to be determined.