色素上皮细胞衍生因子与脉络膜新生血管性疾病

色素上皮细胞衍生因子(pigment epithelium-derived factor,PEDF)是一种分泌蛋白,相对分子量为50000,属于丝氨酸超家族的一员。近年来大量研究发现PEDF具有多种生物学功效,包括抗新生血管、神经营养及神经保护功能。PEDF是最有效的内源性眼部新生血管抑制物。PEDF对于治疗血管增生性疾病及视网膜变性疾病具有广阔的前景,就近年来关于PEDF的研究进展及其与脉络膜新生血管性疾病的相关研究进展给以综述。     

色素上皮细胞衍生因子基因治疗视网膜及脉络膜新生血管性疾病研究进展

色素上皮细胞衍生因子（pigment epithelium—derived factor，PEDF）是一种相对分子质量为50000的分泌蛋白，属于丝氨酸超家族的一员。近年来研究发现PEDF具有多种生物学功效，包括抗新生血管，神经营养及神经保护功能。PEDF是最有效的内源性眼部新生血管抑制物。PEDF对于治疗血管增生性疾病及视网膜变性性疾病具有广阔的前景，基因转移为眼内组织治疗药物的持续传递提供了有效途径。就近年来关于PEDF基因治疗视网膜及脉络膜疾病的研究进展给以综述。     

色素上皮源性因子与眼新生血管性疾病

色素上皮源性因子(pigmentepithelium-derivedfactor,PEDF)是丝氨酸蛋白酶抑制剂超家族成员之一,在眼组织中广泛分布,是内源性新生血管抑制因子的代表。PEDF的相关研究有可能为眼部新生血管性疾病带来新的治疗前景。本文就PEDF的眼部分布、与眼新生血管性疾病及其他血管相关因子的关系、作用机制等方面作一综述。     

色素上皮衍生因子与眼部新生血管性疾病

色素上皮衍生因子 (pigmentepithelium derivedfac tor ,PEDF)主要来源于眼部的色素上皮细胞 ,具有抗血管新生和神经营养的双重功效。最早是由胎儿视网膜色素上皮细胞的培养液中分离出来的。目前研究认为PEDF是最有效的内源性眼部新生血管抑制剂 ,对新生血管的形成起着重要的调控作用。我们就PEDF的生物学特性、表达部位、调节机制、抗血管新生的作用机理以及PEDF与眼部新生血管性疾病的研究进展作一综述。     

色素上皮衍生因子(PEDF)的研究进展

糖尿病性视网膜病变、年龄相关性黄斑变性、中心性渗出性脉络膜视网膜病变等许多眼部疾病的共同特征是视网膜或视网膜下新生血管。色素上皮衍生因子（PEDF）是近年来发现的能有效抑制新生血管形成的因子，与血管内皮生长因子（VEGF）等一起控制了新生血管的发生过程。PEDF有抑制新生血管、营养神经、诱导肿瘤细胞凋亡等作用。本文主要综述其上调下调规律、其作用的研究现况及应用前景。     

色素上皮衍生因子及其在眼表疾病发病中的作用

色素上皮衍生因子(pigment epithelium-derived factor,PEDF)是一种内源性糖蛋白,属于非抑制性丝氨酸蛋白酶抑制剂超家族成员。它具有神经营养、抗新生血管、抗炎、抗氧化等生物学功能。大量研究显示,PEDF通过促进角膜神经的再生,抑制角膜新生血管,减轻炎症反应在多种眼表疾病(如角膜炎、角膜新生血管性疾病、干眼等)的发病过程中起保护作用。     

PEDF的研究进展

色素上皮衍生因子(PEDF),是丝氨酸蛋白酶超家族成员,它具有高度保守的序列和独特的分子结构,因具有神经营养,抑制新生血管,抗肿瘤等多种功能而成为研究的热点,其抗新生血管的功能尤为重要.在糖尿病视网膜病变、老年性黄斑变性、CNV、缺血缺氧引起的眼部新生血管疾病中扮演着重要的角色.现就其分子结构,功能,抗新生血管的机制方面的研究进展进行综述.     

色素上皮源性因子在眼科研究中的进展

色素上皮源性因子（PEDF）最初是在胎儿视网膜色素上皮（RPE）细胞条件培养基中发现的一种神经营养因子。PEDF属于丝氨酸蛋白酶抑制剂超家族，是具有神经保护与抑制新生血管的神经营养因子，也是维持角膜、玻璃体无血管状态的主要细胞因子。PEDF的改变与多种眼病相关，尤其是视网膜脉络膜血管性、退行性疾病，也是治疗这类疾病的靶点之一。就PEDF的结构、功能以及在眼科方面的研究作一综述。     

色素上皮衍生因子（PEDF）——一个具有临床潜力多功能因子

糖尿病视网膜病变,年龄相关性黄斑变性,新生血管性青光眼,角膜新生血管等疾病的共同特点为病理性新生血管形成,色素上皮衍生因子（PEDF）,不仅可有效、有选择性地抑制新生血管,还有营养神经、抗纤维化、抗氧化、抗肿瘤等多种作用,PEDF及其肽段衍生物的应用、PEDF的基因转染技术有望成为新生血管性和神经性疾病的治疗方法。现就PEDF表达、分布、功能、研究现状和临床应用前景做一综述。     

色素上皮源性因子在眼部的作用研究

糖尿病性视网膜病变、视网膜静脉阻塞、Eales病、早产儿视网膜病变、年龄相关性黄斑变性等眼病的共同特征为视网膜或视网膜下新生血管。近年发现新生血管形成因子与抑制因子之间的平衡失调是新生血管形成的重要机制。色素上皮源性因子 (pigmentepithelium -derivedfactor,PEDF)是一重要血管形成抑制因子 ,具有抑制新生血管形成、营养神经和促分化的作用。本文主要综述其在眼部的研究现况及治疗展望。     

Changes in Bruch's membrane in experimental hypercholesteremia in rats

PURPOSE: We investigated the effect of high cholesterol diet for the aging changes in Bruch's membrane of rats. METHODS: After feeding a 4% cholesterol diet for 15 weeks to three young rats 3 months old and four aged rats 23 months old, we observed the morphological changes of Bruch's membrane by electron microscopy, and made a comparison with rats fed an ordinary diet. RESULTS: In one young rat fed a high-cholesterol diet, the endothelial basement membrane of the choriocapillaris formed multiple folds separated from the plasma membrane of the endothelium and showed lamellar thickening and crack in some areas. The elastic fiber layer in Bruch's membrane disappeared partly and some new microfibrils appeared. In one aged rat fed a high-cholesterol diet, the endothelial basement membrane of the choriocapillaris showed more lamellar thickening with lumps in some parts. Compared with rats fed an ordinary diet, rats fed a high-cholesterol diet showed thickening of the basement membrane and the changes were more severe. CONCLUSIONS: Our data indicated that high-cholesterol diet might promote age-related changes of Bruch's membrane.     

Advances in imaging in oculoplastics

Color Doppler imaging, computed tomography (CT) and magnetic resonance (MR) imaging are the most precious imaging tools for the clinician in the field of oculoplastics. Orbital and facial vasculature, with its dynamic changes and flow velocities seen in orbital varices, carotid-cavernous fistulas, and dural cavernous arteriovenous malformations, is best detected by Color Doppler imaging. Computed tomography remains the dominant imaging modality in the evaluation of orbital trauma. Helical CT axial scanning with multiplanar reconstruction and three-dimensional CT imaging are most helpful in assessing iatrogenic, traumatogenic, and teratogenic orbital abnormalities. Despite its poor histologic specificity, MR imaging provides superior soft tissue contrast, and contrast-enhanced MR imaging has an established role regarding soft tissue tumor infiltration. The greatest value of MR studies in the evaluation of orbital and palpebral tumors is that it has the capacity to show the precise relation between lesions and adjacent structures before the clinician contemplates a surgical approach. Finally, contrast-enhanced MR imaging proved to be a valuable vascularization indicator based upon the extent of relative enhancement within porous orbital implant in anophthalmic socket.     

Follow-up studies in pattern VECP in demyelinating diseases in children

Spectral sensitivity functions and the transient decrease of sensitivity to short wavelengths after the offset of yellow light (transient tritanopia) were measured by increment threshold techniques in patients suffering from hereditary macular degenerations. Color vision defects were determined by arrangement tests and the anomaloscope. Central areolar choroidal dystrophy was found to produce a mild protan defect and to reduce foveal spectral sensitivity throughout the visible spectrum by a factor of 100; it also abolishes transient tritanopia. Electroretinogram (ERG) was normal, electrooculogram (EOG) subnormal. Stargardt's disease, despite numerous fluorescent macular spots, does not abolish transient tritanopia nor does it reduce spectral sensitivity, although scotopic matches were performed on the Nagel anomaloscope. Only in severe, advanced cases was transient tritanopia reduced and spectral sensitivity found to follow the absorption spectrum of rods. Routine ERGs and EOGs were normal. Vitelliform macular degeneration, despite the ophthalmoscopically pronounced dystrophic macula, produced only very small changes in spectral sensitivity and transient tritanopia, although a widened matching range on the Nagel anomaloscope and electrophysiological abnormalities were found. Apparently damage of the retinal circuit which connects long and short wavelength-sensitive cones, caused by hereditary conditions, is different from that caused by retinotoxic drugs.     

Refractive error in children in a rural population in India

PURPOSE: To assess the prevalence of refractive error and related visual impairment in school-aged children in the rural population of the Mahabubnagar district in the southern Indian state of Andhra Pradesh. METHODS: Random selection of village-based clusters was used to identify a sample of children 7 to 15 years of age. From April 2000 through February 2001, children in the 25 selected clusters were enumerated in a door-to-door survey and examined at a rural eye center in the district. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy and autorefraction under cycloplegia, and examination of the anterior segment, media, and fundus. Myopia was defined as spherical equivalent refractive error of at least -0.50 D and hyperopia as +2.00 D or more. Children with reduced vision and a sample of those with normal vision underwent independent replicate examinations for quality assurance in seven clusters. RESULTS: A total of 4414 children from 4876 households was enumerated, and 4074 (92.3%) were examined. The prevalence of uncorrected, baseline (presenting), and best corrected visual acuity of 20/40 or worse in the better eye was 2.7%, 2.6%, and 0.78%, respectively. Refractive error was the cause in 61% of eyes with vision impairment, amblyopia in 12%, other causes in 15%, and unexplained causes in the remaining 13%. A gradual shift toward less-positive values of refractive error occurred with increasing age in both boys and girls. Myopia in one or both eyes was present in 4.1% of the children. Myopia risk was associated with female gender and having a father with a higher level of schooling. Higher risk of myopia in children of older age was of borderline statistical significance (P = 0.069). Hyperopia in at least one eye was present in 0.8% of children, with no significant predictors. CONCLUSIONS: Refractive error was the main cause of visual impairment in children aged between 7 and 15 years in rural India. There was a benefit of spectacles in 70% of those who had visual acuity of 20/40 or worse in the better eye at baseline examination. Because visual impairment can have a significant impact on a child's life in terms of education and development, it is important that effective strategies be developed to eliminate this easily treated cause of visual impairment.     

Vitrectomy in traumatic cataracts and in the complications of surgery in congenital cataract in children

Vitrectomies were carried out in 35 children with traumatic cataracts and complications of surgery for cataracts, caused by injury to the posterior lenticular capsule and incorporation of its fragments to the vitreous. Complete removal of lenticular rudiments rapidly eliminated phacogenic iridocyclitis and improved visual acuity. Improvement of visual functions was attained in 66.6% cases; in 33.4% cases visual acuity did not change. Hemorrhages to the vitreous cavity occurred in 4 cases with pronounced iridocyclitis; therefore, a corneal approach is preferable for cases with pronounced iridocyclitis.     

Refractive error in children in an urban population in New Delhi

PURPOSE: To assess the prevalence of refractive error and related visual impairment in school-aged children in an urban population in New Delhi, India. METHODS: Random selection of geographically defined clusters was used to identify a sample of children 5 to 15 years of age. From December 2000 through March 2001, children in 22 selected clusters were enumerated through a door-to-door survey and examined at a local facility. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy and autorefraction under cycloplegia, and examination of the anterior segment, media, and fundus. Myopia was defined as spherical equivalent refractive error of at least -0.50 D and hyperopia as +2.00 D or more. Children with reduced vision and a sample of those with normal vision underwent independent replicate examinations for quality assurance in four of the clusters. RESULTS: A total of 7008 children from 3426 households were enumerated, and 6447 (92.0%) examined. The prevalence of uncorrected, baseline (presenting), and best corrected visual acuity of 20/40 or worse in the better eye was 6.4%, 4.9%, and 0.81%, respectively. Refractive error was the cause in 81.7% of eyes with vision impairment, amblyopia in 4.4%, retinal disorders in 4.7%, other causes in 3.3%, and unexplained causes in the remaining 5.9%. There was an age-related shift in refractive error from hyperopia in young children (15.6% in 5-year-olds) toward myopia in older children (10.8% in 15-year-olds). Overall, hyperopia was present in 7.7% of children and myopia in 7.4%. Hyperopia was associated with female gender. Myopia was more common in children of fathers with higher levels of education. CONCLUSIONS: Reduced vision because of uncorrected refractive error is a major public health problem in urban school-aged children in India. Cost-effective strategies are needed to eliminate this easily treated cause of vision impairment.