美国德州大学加尔威史东医学分部（University of Texas Medical Branch，简称UTMB at Galveston）及Neurobiotex公司的研究人员发现，老年黄斑病变(Age-related Macular Degeneration，简称AMD)与眼部的锌含量有很大的关联性。此研究发表于三月份的Experimental Eye Research期刊。UTMB的眼科医师也是此研究的作者Erik van Kuijk表示：「这份研究除了对AMD疾病有更深入的了解外，也有助于科学家针对AMD开发更有效的治疗方法。」
AMD是一种视网膜(retina)退化病变，会导致中央视力逐渐受损。在美国大约有数百万人罹患此疾，特别是年龄超过75岁的老人，罹患率超过30%。又可分为干型老年黄斑病变(Dry AMD)及湿型老年黄斑病变(Wet AMD)。Dry AMD约占所有病例的90%，其黄斑点底部的视网膜色素上皮层细胞(retinal pigment epithelial cells, RPE) 聚积黄白色的沉积物，叫做脉络膜小疣(drusen)。这些沉积物是由感光细胞排出的废物，不知何故，RPE细胞失去了排除drusen的能力，造成细胞逐步退化。虽不会完全失去中央视觉，不过对于微细视力的作业，例如阅读、绘画等带来困难。目前尚无有效医学治疗方法。而Wet AMD病例约占10%，患者黄斑点后部会出现不正常的血管生长，血管爆裂后血液流到黄斑点，使感光细胞受损，会对中央视觉造成严重损害。病患中女性多于男性，大多与家族遗传或抽烟等生活习惯有关。
研究人员就是在脉络膜小疣中发现高量的锌，对于这项发现Kuijk一点也不意外，因为锌也负责阿兹海默症病人脑部斑点的形成，所以推测锌可能也是造成AMD的因子。Neurobiotex公司的Frederickson博士就表示：「AMD可视为眼部的阿兹海默症。因为这两种疾病都与折迭错误的amyloid蛋白有关，且锌或铜都会进入斑点中。」研究人员发现在斑点中大约含有5~10%的游离态或结合松散的锌，虽然锌对于细胞的构型很重要，但浓度过高仍会造成许多问题。因此，研究人员使用能獒合锌离子的试剂ZP-1以抓取过多的游离态锌离子，看看是否能减缓AMD的病情。
UTMB黄斑退化症研究中心的主任Michael Boulton表示：「Kuijk研究团队的发现对于AMD的了解具有卓越的贡献，若能在早期就阻止或预防过量的游离锌对眼疾造成的恶化，将能保护视网膜细胞不受到损坏，也将能改善美国超过七百万名AMD病人的生活质量。」
(资料来源 : Bio.com)
英文原文：
3/24/2007 12:15:00 PM ET Related symbols: AMD
NetIndia123.com
Zinc may be behind age-related mascular degeneration
Washington | March 23, 2007 1:24:42 PM IST
US scientists have discovered zinc's involvement in age-related macular degeneration (AMD), the leading cause of blindness in the elderly in developed countries.
Researchers at the University of Texas Medical Branch at Galveston (UTMB) and the Galveston-based spinoff Neurobiotex, Inc. found high levels of zinc in deposits in the eye, which are an indication of AMD.
UTMB ophthalmologist Erik van Kuijk, senior author of the study, says that the new findings contributed to a better understanding of AMD and may facilitate the development of effective treatments.
The researchers said that an early sign and a presumed trigger of the eye disease is the formation of microscopic plaques, called 'drusen,' in the eye. Exactly what these plaque-like drusen do and why they form is not yet fully understood, they noted. We have discovered that the drusen in the eyes of those with AMD have very high levels of zinc,' said van Kuijk, associate professor in the UTMB Department of Ophthalmology and Visual Sciences.
Since zinc had previously been shown to contribute to the formation of brain plaques in patients with Alzheimer's disease, van Kuijk said that it was logical to test whether zinc might also contribute to the formation of the plaque-like drusen in the eye. He said that they do so using a reagent called ZP-1. 'What is particularly important is that within the zinc we found a small pool - about 5 to 10 percent - of what is known as 'free' or 'loosely bound' zinc,' van Kuijk explained. 'Generally, zinc is essential to keeping a molecule's shape, but mobilised zinc can cause lots of problems. However, since it is a small proportion of the overall zinc pool, it's straightforward to target it. That's what researchers are beginning to do with Alzheimer's disease by developing methodologies and drugs that can capture this mobilised zinc and see if doing that slows down the degenerative process. This study shows that we could now potentially take a similar route for AMD treatment,' he added. The researchers looked at eyes procured by the Montana Eye Bank from deceased patients with AMD that contained several large sub-RPE deposits and compared them to post-mortem eyes from a similar age group that had no known eye disease and no deposits in the macula. They analysed these using zinc-sensing molecules like ZP-1, which glow when they bind with zinc. 'The pioneering work by Dr. van Kuijk and his colleagues is an important development in our understanding of AMD. The possibility of targeting zinc to stop or reverse drusen growth is important because doing so has the potential to arrest the progression of AMD early, before irreversible damage to the retinal cells occurs' said Dr Michael Boulton, director of the new Macular Degeneration Center at UTMB.'A treatment for AMD is desperately needed as the disease affects up to 7 million Americans. This equates to 2,000 AMD sufferers here on Galveston Island,' Boulton added. The new findings have been published in the journal Experimental Eye Research. (ANI) Researchers at the University of Texas Medical Branch at Galveston (UTMB) and the Galveston-based spinoff Neurobiotex, Inc. found high levels of zinc in deposits in the eye, which are an indication of AMD. UTMB ophthalmologist Erik van Kuijk, senior author of the study, says that the new findings contributed to a better understanding of AMD and may facilitate the development of effective treatments. The researchers said that an early sign and a presumed trigger of the eye disease is the formation of microscopic plaques, called 'drusen,' in the eye. Exactly what these plaque-like drusen do and why they form is not yet fully understood, they noted. We have discovered that the drusen in the eyes of those with AMD have very high levels of zinc,' said van Kuijk, associate professor in the UTMB Department of Ophthalmology and Visual Sciences. Since zinc had previously been shown to contribute to the formation of brain plaques in patients with Alzheimer's disease, van Kuijk said that it was logical to test whether zinc might also contribute to the formation of the plaque-like drusen in the eye. He said that they do so using a reagent called ZP-1. 'What is particularly important is that within the zinc we found a small pool - about 5 to 10 percent - of what is known as 'free' or 'loosely bound' zinc,' van Kuijk explained. 'Generally, zinc is essential to keeping a molecule's shape, but mobilised zinc can cause lots of problems. However, since it is a small proportion of the overall zinc pool, it's straightforward to target it. That's what researchers are beginning to do with Alzheimer's disease by developing methodologies and drugs that can capture this mobilised zinc and see if doing that slows down the degenerative process. This study shows that we could now potentially take a similar route for AMD treatment,' he added. The researchers looked at eyes procured by the Montana Eye Bank from deceased patients with AMD that contained several large sub-RPE deposits and compared them to post-mortem eyes from a similar age group that had no known eye disease and no deposits in the macula. They analysed these using zinc-sensing molecules like ZP-1, which glow when they bind with zinc. 'The pioneering work by Dr. van Kuijk and his colleagues is an important development in our understanding of AMD. The possibility of targeting zinc to stop or reverse drusen growth is important because doing so has the potential to arrest the progression of AMD early, before irreversible damage to the retinal cells occurs' said Dr Michael Boulton, director of the new Macular Degeneration Center at UTMB. 'A treatment for AMD is desperately needed as the disease affects up to 7 million Americans. This equates to 2,000 AMD sufferers here on Galveston Island,' Boulton added. The new findings have been published in the journal Experimental Eye Research. (ANI)
