Biomedical subjects

Adiel Barak

Publications and source records attributed to Adiel Barak.

9 recordsLinked to original sources

PubMed2006

Electrophysiologic and retinal penetration studies following intravitreal injection of bevacizumab (Avastin).

PURPOSE: Intravitreal bevacizumab (Avastin; Genentech Inc., San Francisco, CA) is a new treatment for age-related macular degeneration. The aim of this study was to evaluate retinal penetration and toxicity of bevacizumab. METHODS: Ten albino rabbits were injected intravitreally with 0.1 mL (2.5 mg) of Avastin into one eye and 0.1 mL saline into the fellow eye. The electroretinogram (ERG) was recorded after 3 hours, 3 days, and 1, 2, and 4 weeks. The visual evoked potential (VEP) was recorded after 4 weeks. Confocal immunohistochemistry was used to assess retinal penetration. RESULTS: The ERG responses of the control and experimental eyes were similar in amplitude and pattern throughout the follow-up period. The flash VEP responses of the experimental eyes were of normal pattern and amplitude and did not differ from those recorded by stimulation of the control eye alone. Full thickness retinal penetration was present at 24 hours and was essentially absent at 4 weeks. CONCLUSIONS: Bevacizumab was found to be nontoxic to the retina of rabbits based on electrophysiologic studies. Full thickness retinal penetration may explain observed clinical effects of intravitreal bevacizumab. Although it is difficult to directly extrapolate to humans, our study supports the safe use of intravitreal bevacizumab injection.

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PubMed2006

Intravitreal triamcinolone injection for diffuse diabetic macular edema with foveal cystoid changes.

BACKGROUND: Diabetic macular edema causes visual loss in almost one-third of diabetic patients. There is currently no treatment for the accompanying cystoid foveal changes. OBJECTIVES: To assess the clinical outcome, i.e., change in visual acuity, in patients treated with steroids for long-standing diabetic macular edema with foveal cystoid changes. METHODS: In the ophthalmology department of a tertiary care university-affiliated medical center and the ophthalmology service of a health management organization, 46 diabetic subjects (56 eyes) who had diabetic macular edema with cystoid foveal changes received one intravitreal injection of 4 mg triamcinolone acetonide. RESULTS: The mean baseline (pre-injection) visual acuity of 0.21 increased to 0.31 and 0.48 at 1 and 3 months, respectively, after which it decreased to 0.33 at 6 months. The mean intraocular pressure was 15.07 mmHg at baseline, 15.83 at day 1, gradually rising to 17.16, 18.38 and 18.57 mmHg at 1, 3 and 6 months respectively. Three patients suffered immediate visual decline after the injection. CONCLUSIONS: Intravitreal triamcinolone acetonide may be a therapeutic option for long-standing diabetic macular edema with foveal cystoid changes.

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PubMed2005

Endogenous Phialemonium curvatum endophthalmitis.

PURPOSE: To report a case of bilateral endogenous Phialemonium curvatum endophthalmitis, secondary to intrapenile injections for erectile dysfunction. DESIGN: Observational case report. METHODS: A 71-year-old man with P. curvatum endocarditis and bilateral decreased vision was diagnosed as having bilateral endogenous endophthalmitis. P. curvatum was identified in cultures that were performed on samples of the vitreous. Treatment consisted of bilateral vitrectomy and intraocular and systemic antifungals. RESULTS: Despite resolution of the systemic infection, the patient's postoperative visual acuity remained limited to hand movement, and the ophthalmic clinical picture remained unchanged. CONCLUSIONS: P. curvatum is a pathogen that can be readily isolated from the vitreous. The authors are unaware of previous reported cases of ocular infection that was caused by P. curvatum.

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PubMed2005

Laser induces apoptosis and ceramide production in human retinal pigment epithelial cells.

PURPOSE: To investigate the cellular mechanisms involved in the cell death of human retinal pigment epithelial (hRPE) cells after their exposure to laser injury. METHODS: Cultured human hRPE cells were irradiated for different lengths of time and at different levels of energy using diode laser photocoagulation coupled with an intraocular laser probe. Apoptosis was determined by TUNEL staining and annexin-V labeling of phosphatidylserine exposure. Ceramide levels were quantified by the diacylglycerol kinase assay using thin-layer chromatography. RESULTS: Laser irradiation caused areas of apoptosis in the hRPE cells. These areas were detected around the ablated and necrotic laser scar and developed several hours after the laser irradiation. Laser irradiation concomitantly induced an increase in the intracellular production of ceramide, a lipid second messenger. CONCLUSIONS: The results demonstrate that laser irradiation induces apoptosis in hRPE cells and suggest that the underlying signaling mechanism involves ceramide generation.

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PubMed2005

Nonproteinuric diabetes-associated nephropathy in the Cohen rat model of type 2 diabetes.

The Cohen diabetic rat is an experimental model reminiscent of human type 2 diabetes. The aim of this study was to characterize the development of end-organ damage in this model. Cohen diabetic sensitive (CDs) and Cohen diabetic resistant (CDr) rats were fed regular diet or a diabetogenic diet. Glucose tolerance, renal function, and renal and retinal histology were studied at set intervals. CDs fed diabetogenic diet were the only strain that expressed the diabetic metabolic phenotype. In this strain, urinary protein excretion did not increase with the development of diabetes, but plasma urea and creatinine levels increased and creatinine clearance decreased. Light microscopy revealed in CDs enlarged glomeruli with increased mesangial matrix and thickening of the glomerular capillary wall; electron microscopy demonstrated thickened basement membrane and mesangial abundance. There was increased staining for type IV collagen in glomeruli and interstitium of CDs. The retinas of diabetic CDs demonstrated pathology consistent with nonproliferative diabetic retinopathy. The histological findings in the kidneys, the absence of proteinuria, the impairment in glomerular filtration, and the development of retinopathy in CDs are consistent with diabetes-associated nephropathy that is similar to a nonalbuminuric type of nephropathy associated with type 2 diabetes in humans.

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PubMed2004

Co-existence of intraocular and orbital lymphoma.

BACKGROUND: The concomitant occurrence of both intraocular and periocular lymphomas is extremely rare. Periocular involvement by lymphoproliferative disease ranges from benign lymphoid hyperplasia to malignant lymphoma. Intraocular lymphomas usually appear in conjunction with primary central nervous system lymphoma. CASE REPORTS: We describe clinical characteristics, standardized A- and B-scan ultrasonography, colour Doppler, computerized tomographic and magnetic resonance imaging, and immunohistological findings in three cases of concurrent choroidal and periocular involvement of lymphoma. DISCUSSION: The clinical presentation of diffuse choroidal tumours may be variable, making diagnosis of intraocular lymphoma troublesome on clinical grounds alone. The high accuracy of colour Doppler imaging is known to be effective in differentiating the benign from the malignant and adds valuable information in the differential diagnosis of a low reflective lesion. We suggest the use of auxiliary examinations such as ultrasonography and colour Doppler imaging to help in the differential diagnosis of choroidal and orbital tumours.

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PubMed2003

Replacing the Amsler grid: a new method for monitoring patients with age-related macular degeneration.

PURPOSE: To investigate a method that uses hyperacuity, the Macular Computerized Psychophysical Test (MCPT), to evaluate the central macular visual field in patients with age-related macular degeneration (AMD). DESIGN: Prospective case-control study of a diagnostic test. PARTICIPANTS AND CONTROLS: One hundred eight eyes of 108 Patients with AMD and 51 eyes of 51 age-matched patients with no retinal disease. Patients with AMD included 32 (30%) patients with choroidal neovascularization (CNV), 23 (21%) with geographic atrophy (GA), 35 (32%) with AMD with high-risk characteristics (HRC), and 18 (17%) with early AMD with non-HRC. TESTING: Each subject underwent the MCPT, in which a virtual line composed of dots (white dots on a black background, maximal contrast) is flashed across different macular loci to a perifoveal radius of 7 degrees. Patients' responses were recorded and automatically analyzed using a specific algorithm developed before the onset of the study. All patients also underwent a supervised Amsler grid examination on the encounter before or after the MCPT in random order. MAIN OUTCOME MEASURES: Distortion, scotoma, or blurring perceived by the patient after a swift change of fixation was considered positive on the MCPT. Any perception of distortion, scotoma, or blurring was considered positive on the Amsler grid. RESULTS: Of the 32 patients with CNV, 30 (94%) were found positive on the MCPT and 11 (34%) were found positive on the Amsler grid. Of the 23 GA patients, 21 (91%) were found positive on the MCPT and 7 (30%) were found positive on the Amsler grid. Of the 35 HRC patients, 28 (80%) were found positive on the MCPT and 3 (9%) were found positive on the Amsler grid, and of the 18 early AMD with non-HRC patients, 8 (44%) were found positive on the MCPT and 3 (17%) were found positive on the Amsler grid. Of the 51 controls, 3 (6%) were positive on the MCPT and 1 (2%) was positive on the Amsler grid. CONCLUSIONS: The MCPT was superior to the Amsler grid in detecting AMD-related lesions in this cohort. Studies are underway to determine whether the MCPT is feasible for home monitoring to provide early detection of progression to CNV.

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PubMedDate not supplied

Results of a multicenter clinical trial to evaluate the preferential hyperacuity perimeter for detection of age-related macular degeneration.

PURPOSE: To compare the preferential hyperacuity perimeter (PHP) with an Amsler grid in detection of age-related macular degeneration (AMD). METHODS: Patients underwent refraction, visual acuity examination, PHP, Amsler grid examination, and macular photography. RESULTS: One hundred fifty patients participated in the trial. Of 19 eyes with neovascular AMD, 19 (100%) were positive on the PHP, and 10 (53%), on the Amsler grid. Of 27 eyes with geographic atrophy, 26 (96%) were positive on the PHP, and 12 (44%), on the Amsler grid. Of 20 eyes with intermediate AMD, 14 (70%) were positive on the PHP, and 4 (20%), on the Amsler grid. Of 51 eyes with early AMD, 21 (41%) were positive on the PHP, and 4 (8%), on the Amsler grid. Of 33 eyes with no AMD, 6 (18%) were positive on the PHP, and none, on the Amsler grid. Thus, 80 (68%) of 117 patients with AMD had a positive PHP, while 30 (26%) had positive results of Amsler grid examination (P < 0.001, McNemar test). CONCLUSION: The PHP had greater sensitivity, although with a relatively high rate of false-positive results for healthy individuals, than the Amsler grid in detecting AMD-related lesions.

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PubMedDate not supplied

Visual field defects after radial optic neurotomy for central retinal vein occlusion.

PURPOSE: Surgical decompression of the vein in central retinal vein occlusion (CRVO) by radial optic neurotomy (RON) was recently proposed as being surgically feasible, safe, and beneficial. The effect of RON on the visual field has not been systematically reported, although possible visual field defects are expected due to iatrogenic cutting of the optic nerve fibers. The authors report the results of visual field testing in patients who underwent RON at the Tel Aviv Medical Center. METHODS: Twelve consecutive patients (8 men, mean age of all patients 68 years) with nonperfused or indeterminate CRVO whose initial visual acuity (VA) was < or =20/400 underwent RON. Nine of these patients were able to perform visual field tests at 6 months post-RON and their visual field results are presented. RESULTS: : VA improved by > or =3 lines in 5 patients (42%). Three (25%) patients had a final VA of > or =20/200 and another had a final VA > or =20/50. Fundus and VA improvement were relatively slow. Two patients had clearing of the intraretinal blood, resolution of the venous dilation, and improved VA at the 2-month follow-up visit. Temporal visual field defects consisting of temporal ones that could be correlated to the site of the RON incision were detected in five out of the nine patients who were able to perform visual field tests. No temporal visual field defects were found in the remaining four patients, and three other patients were unable to perform visual field tests due to inability to identify the largest target size. CONCLUSION: VA improvement in 5 of 12 patients with ischemic or indeterminate CRVO following RON may be better than the natural history of CRVO. The risk of visual field defects may, however, be heightened by possibly cutting off blood supply to the optic nerve head and possible damage to nerve fibers in the optic nerve head, both inherent to the surgical procedure and both likely to produce visual loss.

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