Small-Angle Neutron Scattering Studies of Hemoglobin Confined Inside Silica Tubes of Varying Sizes

In addition to the chemical nature of the surface, the dimensions of the confining host exert a significant influence on confined protein structures; this results in immense biological implications, especially those concerning the enzymatic activities of the protein. This study probes the structure of hemoglobin (Hb), a model protein, confined inside silica tubes with pore diameters that vary by one order of magnitude (approximate to 20-200 nm). The effect of confinement on the protein structure is probed by comparison with the structure of the protein in solution. Small-angle neutron scattering (SANS), which provides information on protein tertiary and quaternary structures, is employed to study the influence of the tube pore diameter on the structure and configuration of the confined protein in detail. Confinement significantly influences the structural stability of Hb and the structure depends on the Si-tube pore diameter. The high radius of gyration (R-g) and polydispersity of Hb in the 20 nm diameter Si-tube indicates that Hb undergoes a significant amount of aggregation. However, for Si-tube diameters greater or equal to 100 nm, the R-g of Hb is found to be in very close proximity to that obtained from the protein data bank (PDB) reported structure (R-g of native Hb=23.8 angstrom). This strongly indicates that the protein has a preference for the more native-like non-aggregated state if confined inside tubes of diameter greater or equal to 100 nm. Further insight into the Hb structure is obtained from the distance distribution function, p(r), and ab initio models calculated from the SANS patterns. These also suggest that the Si-tube size is a key parameter for protein stability and structure.

黄土丘陵沟壑区不同恢复方式下植物群落的土壤水分和养分特征

现存不同植物群落的土壤水分和养分特征对有效干预和调控植被恢复有着非常重要的参考价值。在黄土高原丘陵沟壑区的吴旗,对不同恢复方式(封禁下的自然恢复、无管理下的自然恢复、人工造林、人工种草)下的植被样方进行调查与采样,采用典范变量分析,研究了不同植物群落的土壤水分和养分变化特征。结果表明,封禁自然恢复植物群落的土壤水分、有机质、全氮、有效氮、全磷和速效钾含量相对较高;近20年龄及以上的人工林地群落与人工草地群落下的土壤水分和速效磷含量很低;无管理下的自然恢复植物群落、4年龄的沙棘林地群落和农田的土壤水分含量和速效磷含量较高,而土壤有机质、全氮、有效氮、全磷和速效钾含量较低。这些植被群落下的土壤水分含量变化在凋萎湿度和50%田间持水量之间,均处于严重亏缺状态,土壤养分也处于较低的水平。相比之下,人工植被消耗大量的深层土壤水分,特别是20年龄以上的人工林地及人工草地,其200~500cm土层的土壤含水量几乎接近凋萎湿度。综合分析表明,封禁自然恢复是黄土高原丘陵沟壑区植被恢复的有效措施。

中国近海浮游细菌生物量与生产力的生态分布特点

本论文研究了胶洲湾、东海和渤海的蓝细菌（Synechococcus）、生物量、异养细菌生物量和生产力的生态学特点。并在汇泉湾、渤海和东海用分极增减法对海洋蓝细菌在微型食物环（the microbial loop）中的作用进行了初步研究。在以上海区调查研究的时间如下：胶州湾：1993年2月、5月、9月11月，1996年5月、1999年3月、5月和12月。汇泉湾：1996年4月至1998年4月。东海：1997年2-3月，1998年7月。渤海1998年9-10月，1999年4-5月。研究结果如下：胶州湾：蓝细菌生物量的变化范围是11.4-0.03 mgC/m~3，季节变化是夏季>秋季和春季>冬季。其水平分布是除夏季蓝细菌生物量是沿岸浅水区向湾外递减外，其它三季（春、秋和冬季）是由湾外向湾内至沿岸浅水区递减。蓝细菌生物量与海水温度周年变化正相关，与季节海水温度的关系是秋、冬季分布变化一致，春、夏季分布变化相反。海水温度是影响胶州湾蓝细菌生物量分布变化的主要原因。异养细菌生物量和生产力的变化范围分别是29.8-1.62 mgC/m~3; 129.12-1.92 mgC/m~3.d。季节变化都是夏季>秋季、春季>冬季。夏季的异养细菌生物量和生产力水平分布趋势与蓝细菌生物量的分布变化相同。海水温度对异养细菌生产力的影响较对异养细菌生物量的影响大。异养细菌生产力相比（BP:PP）的变化在0.58-0.02之间，季节分布变化是夏季>秋季、春季>冬季。夏季表层的BP:PP由沿岸浅水区向湾心、湾口和湾外递减。东海：蓝细菌生物量的变化范围是46.72-0.011 mgC/m~3，夏季高平均是23.59 mgC/m~3，冬季低平均是3.61 mgC/m~3。冬季蓝细菌生物量的水平分布明显受黑潮的影响，在表面和20米层是由东南向西北方向递减。其垂直分布是冬季表层和20米层>底层，夏季是20米层>表层>底层；在连续站冬111站和410站变化都是中层>底层>表层。异养细菌生物量和生产力的变化范围分别是17.2-4.4 mgC/m~3（1997.2）；376.8-7.2 mgC/m~3.d。异养细菌生产力夏季高平均是35.1 mgC/m~3.d。异养细菌生物量的水平分布是由沿岸向外海递增（1997.2），异养细菌生产力的水平分布是冬季异养细菌生产力在32度断面有由沿岸向外递减趋势，PN断面的变化与冬季相似。垂直分布，冬季和夏季的异养细菌生产力的垂直变化在2断面是底层大于表面，PN断面则是表层大于底层，32度断面大多断站是底层大于表层。在连续站冬季111站异养细菌生产力的变化是底层>中层>表层，409站的变化是中层>底层>表层，夏季111站和410站都是中>底层>表层。异养细菌生物量（1997.2）表层分布变化与海水温度分布变化相似，底层变化相反。异养细菌生产力与初级生产力相比（BP:PP），冬季在0.04-0.30之间，平均为0.17；夏季在0.20-0.43之间平均0.32。冬季在长江口附近BP：PP有一个高值区是0.30，夏季在111站附近有一个高值区是0.43。从连续站111站和409’站观测发现底层的BP：PP明显高于表层。渤海：蓝细菌生物量秋季（16.6-0.37 mgC/m~3）比春季（0.44-0.015 mgC/m~3）高。其秋季的水平分布与海水盐度水平分布相同，与海水温度水平分布相反。异养细菌生产力秋季（189-62.2 mgC/m~3.d）与春季（193.2-49.8 mgC/m~3.d）相当。但秋季捕层BP普遍小于底层，而春季是表层普遍大于底层。根据颗粒分级培养实验结果，海洋蓝图细菌在微型食物环中的作用如下：在汇泉湾的春季和秋季蓝细菌可能主要被小型浮游动物（microzooplankton 20-200 μm）捕食。在渤海的春季和秋季也是同样结果。但在东海夏季的111站和410站附近（东海大陆架中部）微型浮游动物（nanozooplankton 2-20 μm）对蓝细菌的捕食压力明显。

微型浮游动物及其对浮游植物的摄食压力

本论文研究了渤海，胶州湾和东海20-200 μm微型浮游动物（桡足类幼虫、纤毛虫）的数量和生物量（1% Lugol's 试剂固定1000ml，Utermohl法150倍显微镜检查），在渤海和东海用稀释法（Landry and Hassett, 1982; Burkill et al., 1990）估计了微型浮游动物（<200 μm）对浮游植物的摄食压力。对上述海区调查的时间如下：渤海：1997年6，1998年6月（莱州湾），1998年10月；胶州湾1997年8、11月，1998年2、4、8、11月，1999年2月；东海：1998年7月。结果如下：渤海：1997年6月，只发现一种砂壳纤毛虫，数量为0-980个/L。1998年6月（莱州湾），微型浮游动物数量为30-2390个/L，生物量为1.5-25 μg C/L，水体中生物量为0.1-53.2 mgC m~(-2)。共有13种砂壳纤毛虫和一种无壳纤毛虫。纤毛虫的数量为0-2380个/L，生物量为0-24.52 μg C/L。纤毛虫优势种有无壳纤毛虫、Tintinnopsis pallida、T. amoyensis和T. chinglanensis。微型浮游动物的各个类群呈斑块分布。1998年10月，微型浮游动物的数量为0-770个/L，生物量为0-12.3 μg C/L，水体中生物量为0-136 mgC m~(-2)。在两次大面调查间隔的6天内，发生大风。两次大面站调查海区的温盐分布格局没有很大变化，但微型浮游动物的变化却十分显著，这也反映了恶劣天气对海洋生物的影响。在几个连续站对微型浮游动物的连续监测表明，微型浮游动物的分布与水团有很大关系。胶州湾：桡足类幼虫在8月数量最大（850个/L）。共记录两种无壳纤毛虫和7种砂壳纤毛虫。微型浮游动物数量弯化很大，从10-22600个/L。微型浮游动物的分布格局可能是湾内和湾外海水混合的结果：1997年11月，无壳纤毛虫No.12从湾外涌入，其他航次无壳纤毛虫No.11在湾内发生，向湾外扩散。东海：微型浮游动物数量较少，最大数量为1970个/L，绝大多数站位低于300个/L，生物量为0.08-45 μg C/L，水体50m积分生物量为5-283mgC m~(-2)。微型浮游动物有明显的斑块分布，连续监测没有发现明显的变化。根据稀释培养的结果，微型浮游动物对浮游植物摄食压力如下所述：渤海三个航次的微型浮游动物对浮游植物摄食率为0.13-1.01d~(-1)，每天摄食浮游植物生物量（现存量）的12-49%，初级生产力的34-267%。东海稀释培养的结果为微型浮游动物地浮游植物的摄食率为0.2-1.2d~(-1)，每天摄食浮游动物生物量的20-71%，摄食初级生产力的54-98%。由于稀释培养实验的设计和操作有许多争议之外，本文只将结果列出，对方法不作讨论。

中国若干典型海域作用于浮游植物上、下行效应的研究

在胶州湾内、东海与南海通过现场实验(营养盐添加实验与稀释实验)的方法，对N(N0_3~--N、NH_4~+-N)、P、Fe、Si营养盐以及小型浮游动物对浮游植物生长的调控机制进行了初步研究。同时还在胶州湾内开展了上、下行效应的比较研究，主要结果如下：1 在胶州湾内共进行了25次富营养现场实验与12次稀释实验，网采浮游植物(20-200μm)与微型浮游植物(2-20μm)是叶绿素a生物量的主要组成部分，比较而言，在周年的水平上，微型浮游植物比网采浮游植物更多的支配着浮游植物群落的叶绿素a生物量。在营养盐添加实验中，培养后期浮游植物群落也都是网采浮游植物与微型浮游植物占叶绿素a生物量的优势地位。胶州湾是营养盐含量较高，且营养盐变化不规律的海区，但胶州湾各季节的DIN／P基本都大于16:1的Redfield比值。营养盐添加实验的结果显示，在湾内，似乎在秋季无营养盐限制浮游植物生长的情况发生；而在冬、春季发生Si限制的可能性很大；除Fe外，在夏季似乎N(NO_3~--N、NH_4~+-N)、P、Si营养盐限制都有可能发生，但无明显的规律性。在周年的水平上，Si似乎是最主要的限制性营养盐，而P与N都可能产生次级营养盐限制。营养盐添加实验中分级叶绿素的结果显示，网采浮游植物与微型浮游植物在冬、春季一般会经历较显著的Si限制作用，在夏季N似乎对网采浮游植物与微型浮游植物的生长有更重要的调控作用。超微型浮游植物的生长似乎主要受到P的调控。在胶州湾内，网采浮游植物的生长似主要受到上行效应的调控，而下行效应似是控制超微型浮游植物生长的主要机制。从整个浮游植物群落(<200μm)的周年变化情况来看，在控制浮游植物的生物量上，似乎下行效应比上行效应更有效。 2在东海，除402站(122°33'E、30°45'N)位于长江口，受到显著的陆源输入影响外(特别是该站有相当高的SiO_3~(2-)-Si含量)，418站(127°30'E、27°55'N)、Y136站(128°、30°27')与E064(125°14'E、25°48'N)站都位于开放海区，营养盐含量都很低。1999年的航次，表层的硝酸盐与铵盐含量都比1998年的航次高，但另外三种常量营养盐含量都低。402站有较高比例的网采浮游植物与微型浮游植物叶绿素a生物量，相应的超微型浮游植物占总叶绿素a生物量的比例则显著低于其它三站。位于陆架区的Y136站，其微型浮游植物叶绿素a生物量则显著低于沿岸海区，但超微型浮游植物叶绿素a生物量则显著增加，占总叶绿素a的50％以上。处于开放海区的418站与E064站，网采浮游植物叶绿素a生物量所占的比例已经很低，而无一例外的是超微型浮游植物叶绿素a生物量贡献了总叶绿素a生物量的大部分。但在培养后期，各组处理中网采浮游植物占总叶绿素a生物量的比例都高于初始值。营养盐添加实验的结果显示，沿岸海水中，从比例上看，浮游植物的生长似乎更需要N而不是P，但是太高的N／P添加对浮游植物生长的促进作用反不如适中的N／P的添加；在418站，各种营养盐的添加对浮游植物的生长都有促进作用(Fe除外)，但P的作用更显著一些，在添加的两种N源中，NH_4~+-N的作用比NO_3~--N的作用更显著；在E064站，培养中各实验组的总叶绿素a生物量都有不同程度的增加，但NH_4~+-N与NO_3~--N的作用更显著；Y136站的实验结果与E064站相似，也是NH_4~+-N与NO_3~--N的作用更显著，而且该站Si的作用还比较显著(强于P)。在开放海区，1998年夏季，似乎是P限制着浮游植物群落的生长，但在1999年春季则可能是N限制着浮游植物的生物量。稀释实验的结果显示，在长江口附近的402站与开放海区的E064站浮游植物的生长率都显著高于大陆架的Y136站。小型浮游动物的摄食率则无明显的空间变化趋势，除开放海区的E064站显著高外，其它三站摄食率接近。这一结果与浮游物的群落组成，浮游植物的群落组成以及光照、温度等条件有关。营养盐添加实验与稀释实验的结果都证实，更可能是营养盐通过上行效应，而不是小型浮游动物实施下行效应控制着网采浮游植物的的生长；在东海的实验区域似乎是上行效应控制着微型浮游植物的种群数量变动，从营养盐添加实验的结果看，由于时间的不同，似乎有春季N限制与夏季P限制的季节交替；超微型浮游植物的生长也主要受到营养盐的控制，似乎也有春季N限制与夏季P限制的季节交替；摄食对微型浮游植物的生长有一定的调控作用，但这一调控机制并不是十分有效。3　在南海的航次中，表层硝酸盐的平均浓度较低，经常检测不出，但表层磷酸盐、铵盐与硅酸盐的浓度要比东热带太平洋等贫营养海区高。4 断面沿经度横跨大洋，其表层各种营养盐的平均浓度均低于2断面与5断面，（硝酸盐一般都在检测限之下，铵盐与磷酸盐的平均值分别为0.20与0.12 μM)，属于营养盐较低的海区；2断面表层各种营养盐的平均浓度最高(硝酸盐、铵盐与磷酸盐分别为0.29、1.17与O.19μM)；5断面表层平均的营养盐含量介于2断面与4断面之间，但硝酸盐含量经常在检测限之下。K206与K508站在培养实验的初始时刻都是超微型浮游植物占总叶绿素a生物量的大部分，但K409站网采浮游植物、微型浮游植物与超微型浮游植物的叶绿素a生物量分别占总叶绿素a生物量的30％左右。培养中，各组处理中网采浮游植物叶绿素a生物量占总叶绿素a生物量的比例都增加。K409站位于南海中央，该站浮游植物对各种营养盐的添加都有显著的响应效果；K206站位于2断面中部巴士海峡处，本站除P的添加效果较明显外，另外几种营养盐的富营养效果都不显著；K508站磷酸盐与硝酸盐的添加效果较明显。总的来说，各种营养盐的添加对浮游植物的生长都有促进作用，但磷酸盐的作用似乎更显著一些。实验结果可能更反应了N、P、Fe这几种营养盐的共同限制作用。Si限制不如其它几种营养盐显著。南海Fe的限制情况也不严重。各站浮游植物摄食率(g)与生长率(u)的空间变化都不显著。各站的g／u都在0.4左右，说明在南海小型浮游动物的摄食压力比较一致。K409站与K508站浮游植物的生长率显著高于K206站。小型浮游动物的摄食率与浮游植物生长率的变化趋势一致，都是中部的K409站与南边的K508站高于北边的K206站。这可能是各采样站点浮游动物种类组成不同的结果。网采浮游植物似乎主要受到各种营养盐的限制，其中P的作用最显著，N也较显著，随地域不同，间或有Fe的限制作用发生。在南海的中部，可能存在N、P、Fe营养盐对微型浮游植物的共同限制作用，但在北部，可能有微弱的P限制作用，而在大洋的南部，几乎无营养盐限制微型浮游植物的生长，摄食在控制微型浮游植物的生物量上并不是十分有效。超微型浮游植物的生长似乎同时受到营养盐与小型浮游动物摄食的控制，营养盐添加实验的结果显示可能P对超微型浮游植物的生长促进作用最大，同时进行的稀释实验证实，小型浮游动物的摄食活动在调节超微型浮游植物的生长上也相当有效。

SIZE STRUCTURES OF MICROPLANKTON BIOMASS AND PRODUCTION IN JIAOZHOU BAY, CHINA

Seasonal investigations of size-fractionated biomass and production were carried out from February 1992 to May 1993 in Jiaozhou Bay, China. Microplankton assemblages were separated into three fractions: pico-(0.7-2 mu m), nano- (2-20 mu m) and netplankton (20-200 mu m). The biomass was measured as chlorophyll a (Chl a), particulate organic carbon (POC) and particulate organic nitrogen (PON). The production was determined by C-14 and N-15 tracer techniques. The seasonal patterns in biomass, though variable, were characterized by higher values in spring and lower values in autumn and summer (for Chl a only). The seasonal patterns in production, on the other hand, were more clear with higher values occurring in summer and spring, and lower values occurring in autumn and winter. Averaged over the whole study period, the respective proportions of total biomass accounted for by net-, nano- and picoplankton were 26, 45 and 29% for Chl a, 32, 33 and 35% for POC, and 26, 32 and 42% for PON. The contributions to total primary production by net-, nano- and picoplankton were 31, 35 and 34%, respectively. The respective proportions of total NH4+-N uptake accounted for by net-, nano- and picoplankton were 28, 33 and 39% in the daytime, and 10, 29 and 61% at night. The respective contributions to total NO3--N uptake by net-, nano- and picoplankton were 37, 40 and 23% in the daytime, and 13, 23 and 64% at night. Some comprehensive ratios, including C/N biomass ratio, Chl a/C ratio, C uptake/Chl a ratio, C:N uptake ratio and the f-ratio, were also calculated size separately, and their biological and ecological meanings are discussed.

Characterization of a high-density, direct-current reflex discharge plasma source operating in Ar and N-2

The characterization of a direct current, low-pressure, and high-density reflex discharge plasma source operating in argon and in nitrogen, over a range of pressures 1.0-10(-2) mbar, discharge currents 20-200 mA, and magnetic fields 0-120 G, and its parametric characterization is presented. Both external parameters, such as the breakdown potential and the discharge voltage-current characteristic, and internal parameters, like the charge carrier's temperature and density, plasma potential, floating potential, and electron energy distribution function, were measured. The electron energy distribution functions are bi-Maxwellian, but some structure is observed in these functions in nitrogen plasmas. There is experimental evidence for the existence of three groups of electrons within this reflex discharge plasma. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the density of the cold group of electrons is as high as 10(18) m(-3), and the temperature is as low as a few tenths of an electron volt. The bulk plasma density scales with the dissipated power. Another important feature of this reflex plasma source is its high degree of uniformity, while the discharge bulk region is free of electric field. (C) 2002 American Institute of Physics.

High-density and low electron temperature direct current reflex plasma source

A new type of direct current, high-density, and low electron temperature reflex plasma source, obtained as a hybrid between a modified hollow-cathode discharge and a Penning ionization gauge discharge is presented. The plasma source was tested in argon, nitrogen, and oxygen over a range pressure of 1.0-10(-3) mbar, discharge currents 20-200 mA, and magnetic field 0-120 Gauss. Both external parameters, such as breakdown potential and the discharge voltage-current characteristic, and its internal parameters, like the electron energy distribution function, electron and ion densities, and electron temperature, were measured. Due to the enhanced hollow-cathode effect by the magnetic trapping of electrons, the density of the bulk plasma is as high as 10(18) m(-3), and the electron temperature is as low as a few tenths of electron volts. The plasma density scales with the dissipated power. Another important feature of this reflex plasma source is its high degree of uniformity, while the discharge bulk region is free of an electric field. (C) 2004 American Institute of Physics.

Long-term graft survival in patients with flexible open-loop anterior chamber intraocular lenses

Purpose. To evaluate the long-term graft survival in patients with flexible open-loop anterior chamber intraocular lenses (AC IOL). Methods. We retrospectively reviewed the records of patients with aphakic/pseudophakic bullous keratopathy who underwent penetrating keratoplasty and flexible open-loop AC IOL implantation in our institution from 1983 to 1988. Results. 79 eyes from 77 patients were included in the study. Mean follow-up was 50 months (range 1 to 123 months). At last follow-up 61 eyes (77.2%) had clear grafts. Among them, the visual acuity was = 20/40 in 14 eyes (23.0%), 20/50-20/100 in 22 eyes (36.1%), 20/200-20/400 in 9 eyes (14.8%) and = CF in 16 (26.2%). Increment of glaucoma medications and/or glaucoma surgery was the most frequent complication (37 eyes, 46,8%). Cystoid macular edema was newly diagnosed in 10 eyes (12.7%). Conclusions. Flexible, open-loop anterior chamber lens are a viable option in the treatment of patients with aphakic or pseudophakic bullous keratopathy undergoing penetrating keratoplasty.

Visual outcomes in the subfoveal radiotherapy study:A randomized controlled trial of teletherapy for age-related macular degeneration

Objective: To determine whether teletherapy with 6-mV photons can reduce visual loss in patients with subfoveal choroidal neovascularization in age-related macular degeneration. Design: A multicenter, single-masked, randomized controlled trial of 12 Gy of external beam radiation therapy delivered to the macula of an affected eye vs observation only. Setting: Three United Kingdom-based hospital units. Participants: Patients with age-related macular degeneration, aged 60 years and older, who had subfoveal choroidal neovascularization and a visual acuity of 20/200 (logMAR 1.0) or better. Methods: Two hundred three patients were randomly assigned to radiotherapy or observation. Treatment was undertaken at designated radiotherapy centers, and patients assigned to the treatment group received a total dosage of 12 Gy of 6-mV photons in 6 fractions. Follow-up was scheduled at 3, 6, 12, and 24 months. After excluding protocol violators, the data from 199 patients were analyzed. Main Outcome Measures: The primary outcome measure was mean loss of distance visual acuity in the study eye at 12 and 24 months. Other outcome variables analyzed were near visual acuity and contrast sensitivity. The proportions of patients losing 3 or more or 6 or more lines of distance and near acuity and 0.3 or more or 0.6 or more log units of contrast sensitivity at each follow-up were also analyzed. Results: At all time points, mean distance visual acuity was better in the radiotherapy-treated group than in the control group, but the differences did not reach statistical significance. At 24 months, analysis of the proportions of patients with loss of 3 or more (moderate) (P=.08) or 6 or more (severe) (P=.29) lines of distance vision showed that fewer treated patients had severe losses, but there was no statistically significant difference between groups. For near visual acuity, although there was no evidence of treatment benefit at 12 and 24 months, a significant difference in favor of treatment was present at 6 months (P=.048). When analyzed by the proportions of patients losing 3 lines of contrast sensitivity, there was a significant difference in favor of treatment at 24 months (P=.02). No adverse retinal effects were observed during the study, but transient disturbance of the precorneal tear film was noted in treated patients. Conclusion: The results of the present trial do not support the routine clinical use of external beam radiation therapy in subjects with subfoveal choroidal neovascularization in age-related macular degeneration.

Causes and five-year incidence of blindness and visual impairment in urban southern China:The Liwan Eye Study

PURPOSE. We determined the causes and five-year incidence of blindness and visual impairment (VI) in an adult, urban Chinese population. METHODS. Participants underwent a comprehensive eye examination at baseline in 2003 and then five years later. The World Health Organization (WHO) and United States (US) definitions were used to define incident blindness (WHO visual acuity [VA] < 20/400 in the better-seeing eye, US VA ≤ 20/200) and incident VI (WHO VA < 20/60-20/400, US VA < 20/40->20/200). RESULTS. Among 1405 baseline participants, 924 (75%) of 1232 survivors (87.7%) participated in the 5-year follow-up. The incidences of VI and blindness were 5.38% (95% confidence interval [CI] 3.99% ~ 7.07%) and 0.33% (95% CI 0.07% ~ 0.95%), respectively, based on the WHO definition, and 9.85% (95% CI 7.96% ~ 12.0%) and 1.42% (95% CI 0.76% ~ 2.41%), respectively, based on the US definition. Incidence of blindness and VI (WHO definition) increased significantly with older age (P < 0.001) and poorer baseline presenting VA in the worse-seeing eye (P < 0.001). The leading cause of best-corrected VI (WHO definition) was cataract (64.6%), whereas the main causes of presenting VI were refractive error (40.4%) and cataract (38.4%). CONCLUSIONS. The incidence of VI in urban Southern China is high. The major causes are unoperated cataract and undercorrected refractive error, reflecting the need for better surgical and refractive care, even in this urban setting. © 2013 The Association for Research in Vision and Ophthalmology, Inc.

Causes and prevalence of visual impairment among adults in the United States.

OBJECTIVES: To estimate the cause-specific prevalence and distribution of blindness and low vision in the United States by age, race/ethnicity, and gender, and to estimate the change in these prevalence figures over the next 20 years. METHODS: Summary prevalence estimates of blindness (both according to the US definition of < or =6/60 [< or =20/200] best-corrected visual acuity in the better-seeing eye and the World Health Organization standard of < 6/120 [< 20/400]) and low vision (< 6/12 [< 20/40] best-corrected vision in the better-seeing eye) were prepared separately for black, Hispanic, and white persons in 5-year age intervals starting at 40 years. The estimated prevalences were based on recent population-based studies in the United States, Australia, and Europe. These estimates were applied to 2000 US Census data, and to projected US population figures for 2020, to estimate the number of Americans with visual impairment. Cause-specific prevalences of blindness and low vision were also estimated for the different racial/ethnic groups. RESULTS: Based on demographics from the 2000 US Census, an estimated 937 000 (0.78%) Americans older than 40 years were blind (US definition). An additional 2.4 million Americans (1.98%) had low vision. The leading cause of blindness among white persons was age-related macular degeneration (54.4% of the cases), while among black persons, cataract and glaucoma accounted for more than 60% of blindness. Cataract was the leading cause of low vision, responsible for approximately 50% of bilateral vision worse than 6/12 (20/40) among white, black, and Hispanic persons. The number of blind persons in the US is projected to increase by 70% to 1.6 million by 2020, with a similar rise projected for low vision. CONCLUSIONS: Blindness or low vision affects approximately 1 in 28 Americans older than 40 years. The specific causes of visual impairment, and especially blindness, vary greatly by race/ethnicity. The prevalence of visual disabilities will increase markedly during the next 20 years, owing largely to the aging of the US population.

Endothelial cell loss and surgically induced astigmatism after sutureless large-incision manual cataract extraction (SLIMCE).

OBJECTIVES:

To describe a modified manual cataract extraction technique, sutureless large-incision manual cataract extraction (SLIMCE), and to report its clinical outcomes.

METHODS:

Case notes of 50 consecutive patients with cataract surgery performed using the SLIMCE technique were retrospectively reviewed. Clinical outcomes 3 months after surgery were analyzed, including postoperative uncorrected visual acuity, best-corrected visual acuity, intraoperative and postoperative complications, endothelial cell loss, and surgically induced astigmatism using the vector analysis method.

RESULTS:

At the 3-month follow-up, all 50 patients had postoperative best-corrected visual acuity of at least 20/60, and 37 patients (74%) had visual acuity of at least 20/30. Uncorrected visual acuity was at least 20/68 in 28 patients (56%) and was between 20/80 and 20/200 in 22 patients (44%). No significant intraoperative complications were encountered, and sutureless wounds were achieved in all but 2 patients. At the 3-month follow-up, endothelial cell loss was 3.9%, and the mean surgically induced astigmatism was 0.69 diopter.

CONCLUSIONS:

SLIMCE is a safe and effective manual cataract extraction technique with low rates of surgically induced astigmatism and endothelial cell loss. In view of its low cost, SLIMCE may have a potential role in reducing cataract blindness in developing countries.

Autofluorescence Findings Of A Novel Maculopathy In Patient With Spinocerebellar Ataxia Type 1 And Of A Cone - Rod Type Retinal Dysfunction In Three Generation Family With Spinocerebellar Ataxia Type 7

Purpose: To report a novel maculopathy in a patient with SCA1. To describe autofluorescence findings in family with SCA7 and associated cone-rod retinal dysfunction.Methods: 4 affected patients from two families were assessed to investigate a progressive loss of visual acuity (VA). Examinations included fundus photography, autofluorescence (AF) fundus fluorescein angiogragraphy (FFA) and optical coherence tomography. Electroretinogram (full-field) was performed in 2 affected patients. All patients had color vision testing using Ishihara pseudoisochromatic plates. Molecular analysis was performed in family 2.Results: The patient with known diagnosis of SCA1 had a visual acuity of 20/200 bilaterally and dyschromatopsia. He had saccadic pursuit. Fundus examination showed mild retinal pigment epithelium (RPE) changes at the macula. OCT showed bilateral macular serous detachment, which was not obvious at the FFA and explained his VA. AF imaging showed a central hyperfluorescence. The 45 year old proband from family 2 had a visual acuity of 200/20 and dyschromatopsia. ERG testing showed cone type dysfunction of photoreceptors. Her daughter affected at a younger age had the same ERGs findings. Fundus examination showed mild RPE changes in proband, normal findings in her daughter. AF imaging of both patients showed a ring of high density AF around the fovea. The ring was also obvious on near infrared AF. Later onset of gait imbalance led to the diagnosis of SCA7Conclusions: Within the group of spinocerebellar ataxias, only the type 7 is associated with retinal dysfunction. We present the first report of maculopathy associated with SCA1 causing severe vision loss. The ring of high density AF in SCA7 confirmed an early retinal photoreceptor dysfunction in patient with normal fundus.

Análisis del desempeño en materia de Apropiación (Declaración de París, 2005) del gobierno colombiano frente al proyecto de cooperación internacional “Apoyo al Programa de Red de Protección Social contra la Pobreza Extrema (REDEP)” y su alcance frente al cumplimiento de la primera meta de los ODM. Periodo 2006-2010

El presente estudio de caso, pretende a partir de un análisis del principio de Apropiación contenido en la Declaración de París, determinar el desempeño del gobierno colombiano entre los años 2006-2010, frente al proyecto de cooperación internacional "Apoyo al Programa de Red de Protección Social contra la Pobreza Extrema (REDEP)" y su impacto frente al cumplimiento de la primera meta de los Objetivos del Milenio