腺病毒介导睫状神经营养因子在大鼠视网膜中的表达定位

目的观察携带睫状神经营养因子(ciliary neurotrophic factor,CNTF)基因的腺病毒(adenovirus,Ad)载体在正常大鼠视网膜中的表达定位。方法正常成年大鼠40只,随机分为处理组(PBS组、Ad-LacZ组、Ad-CNTF组)及正常对照组,向处理组大鼠眼内分别注射相应溶液,各处理组均分为注射后7d、14d、28d共3个时相点。在相应时相点取大鼠眼球,行冰冻切片,进行免疫组织化学染色。结果Ad-CNTF组各时相点视网膜与其他对照组相比,CNTF阳性染色明显增强,分布更广泛,并且可一直持续到注射后28d。结论Ad-CNTF在正常大鼠眼内注射后,CNTF在视网膜的表达明显增加,且表达时限可达28d。     

急性高眼压大鼠视网膜睫状神经营养因子的表达

目的 :探讨大鼠急性高眼压前后睫状神经营养因子 (CNTF)mRNA在视网膜组织中的表达变化及意义。方法 :利用前房高眼压灌注法 ,使大鼠右眼维持在 110mmHg高眼压 30min ,然后恢复视网膜血供 ,并分别于灌注后 1d、3d处死大鼠 ,用半定量RT PCR方法检测大鼠视网膜组织中CNTFmRNA的表达情况。结果 :在正常大鼠视网膜组织中 ,CNTFmRNA有微量表达 ,急性高眼压后 ,其表达明显增高 ,第 1天、第 3天分别比对照组增加 37.0 9%和 2 2 7.4 2 %。结论 :大鼠急性高眼压损伤后 ,可通过内源性CNTF表达增加来应答视网膜神经节细胞 (RGCs)及其他细胞的损伤 ,保护视网膜及视神经 ,为外源性营养因子的应用提供理论依据。     

Optical fiber properties of individual human cones

The tuning properties of the ensemble of cone photoreceptors is due to the tuning properties of individual cones convolved with the disarray in pointing direction between the cones. We used direct imaging with the Rochester adaptive optics ophthalmoscope to directly image these properties in individual cones in living human eyes. We found that cone disarray is very small, accounting for less than 1% of the breadth of the tuning function of an ensemble of cones. The implication is that the optical fiber properties of an ensemble of cones mimic the tuning properties of a single cone.     

睫状神经营养因子和生长相关蛋白-43在兔眶内慢性视神经损伤中的表达

目的建立眶内视神经慢性受压损伤动物模型,并观察睫状神经营养因子（CNTF）和生长相关蛋白-43（GAP-43）在视神经中的表达。设计实验研究。研究对象新西兰大白兔36只。方法将动物分为6组,即A组（无压迫组）：只放置球囊而不充盈造影剂;B组（2w）：逐量注入造影剂压迫2周;C组（2w＋2w）：压迫2周后解除压迫2周;D组（4w）：注入造影剂压迫4周;E组（4w＋4w）：压迫4周解除压迫4周;F组（8W）：压迫8周。用眼眶内植入气囊并定时注入造影剂的方法,模拟眼眶肿瘤缓慢生长对眶内视神经慢性压迫,建立视神经慢性损伤动物模型;用RT—PCR方法检测在眶内视神经慢性损伤后不同阶段（造模后2、4、8周）CNTF和GAP-43的基因表达。主要指标CNTF和GAP．43的表达。结果眼底像和组织病理检查显示,随着压迫时间的延长,眼底、视网膜和视神经都出现病理改变并逐渐加重。空白及无压迫组低表达CNTF和GAP－43,压迫2周后即可见表达上调（P〈0．01）,随着压迫时间延长,两种基因均见表达逐渐增高（P〈0．01）。结论成功建立兔眶内视神经慢性损伤动物模型,并观察到随着压迫时间的延长,CNTF和GAP-43在视神经中的表达量逐渐增多,提示神经细胞被外来损伤诱导,开始进行自身修复。（眼科,2010．19：135—138）     

Spectral properties and retinal distribution of ferret cones

The spectral mechanisms of the ferret (Mustela putorious furo) were studied with electroretinogram (ERG) flicker photometry. Variations in adaptation state and flicker rate were used to define corneally based spectral sensitivities for the three classes of receptor present in the retina of this mustelid-rods (lambdamax = 505 nm), S cones (430 nm), and L cones (558 nm). The retinal distributions of the two classes of cone were determined using opsin antibody labeling. Ferret retinas contain a total of about 1.3 million cones with L cones outnumbering S cones in a ratio of approximately 14:1. ERGs were also recorded using 18.75-Hz flickering stimuli that were designed to isolate signals from individual cone classes. The contrast/response functions for signals originating from both S and L cones were linear over low-to-moderate levels of contrast, but with greatly different slopes for the two cone types. The L:S contrast gain ratio derived from a comparison of these slopes, as well as inferences drawn from another experiment in which responses to various combinations of L- and S-cone activation were analyzed, suggest that contributions of these two cone types to the flicker ERG have a relative weighting of about 4:1 to 5:1 (L/S).     

大鼠视神经损伤后视网膜CNTF及CNTFRα mRNA的表达

目的研究视神经损伤后睫状神经营养因子及其受体在大鼠视网膜中的表达变化。方法采用钳夹法制作大鼠视神经损伤模型。分别于伤后1、3、7、14、28d取眼球,以正常大鼠视网膜为对照,提取视网膜组织RNA,运用RT-PCR检测视神经损伤后CNTF和CNTFRαmRNA的表达变化。结果在正常视网膜中存在CNTF和CNTFRαmRNA的表达,视神经损伤后CNTF和CNTFRαmRNA表达量逐渐增加,第7d达到最高,第14d下降,具有统计学意义(P<0.01)。28dCNTF表达仍高于正常组(P<0.01)。结论视神经损伤刺激了视网膜细胞表达CNTF和CNTFRα增加,可能是视网膜神经元自我保护的一种反应。     

内源性睫状神经营养因子对青光眼鼠视网膜的保护作用

目的 探讨睫状神经营养因子(CNTF)蛋白在慢性高眼压性青光眼大鼠视网膜中的定位及表达情况.方法采用水下电凝巩膜静脉建立大鼠慢性高眼压性青光眼模型,在1、3、7、14、28 d分别摘取眼球,运用免疫组织化学和Western blot法检测大鼠视网膜CNTF蛋白的定位及表达变化.结果对照组大鼠视网膜神经节细胞(RGCs)层有少量CNTF蛋白表达,青光眼大鼠视网膜CNTF蛋白的表达显著增加,建立模型后第7～14 d表达量达到高峰,此时除了神经节细胞层外,内外核层亦发现有CNTF蛋白的表达,之后表达减少.结论青光眼大鼠视网膜内源性CNTF表达增加,可能与促进损伤的RGCs的存活和轴突再生密切相关.     

NGF在鸡巩膜中的表达及其与形觉剥夺性近视眼形成的关系

目的探讨神经生长因子(NGF)在鸡形觉剥夺性近视形成中巩膜中的表达和变化情况。方法鸡雏30只,随机分为3组,每组10只,于出生后第2 d将右眼以半透明眼罩遮盖作为遮盖眼,左眼开放作为对照眼。分别遮盖3、7、14d。运用免疫组织化学和原位杂交技术探测NGF蛋白及其mRNA在鸡巩膜软骨细胞中的表达。结果NGF蛋白及其mRNA均表达于巩膜的软骨细胞中尤其在双核细胞中;两者在各时间段遮盖眼巩膜中阳性细胞数均明显高于对照组(P<0.05);免疫组织化学(FDG=20.556P<0.01)和原位杂交(FDG=25.520P<0.01)在对照组(或遮盖组)各组间阳性细胞的表达数目随时间变化明显下降。结论NGF对鸡巩膜软骨层的发育和形觉剥夺性近视的形成密切相关。     

NGF在小鸡FDM眼视网膜中表达变化的研究

目的通过研究小鸡形觉剥夺性近视眼视网膜中神经生长因子(nerve growth factor,NGF)表达的变化,以探讨神经生长因子在近视眼形成中的可能作用。方法运用免疫组织化学SP法和原位杂交技术探测神经生长因子及其mRNA在小鸡形觉剥夺性近视(form deprivation myopia,FDM)眼视网膜中的表达。结果正常小鸡眼神经节细胞层、内丛状层和内核层均有NGF蛋白质、mRNA表达,而在FDM眼,内丛状层和内核层变薄,NGF蛋白质、mRNA表达显著上调,与对照组比较,统计学差异均非常显著(P<0.01)。结论NGF极可能作为重要的视网膜信号调控因子参与小鸡FDM的形成。     

Spectral properties of short-wavelength (blue) cones in the turtle retina.

Long- and medium-wavelength cones in the turtle retina participate in complex neural interactions. They are coupled via excitatory pathways to other cones and receive negative feedback inputs from luminosity-type horizontal cells. Little information has been collected on the S- (short-wavelength or blue) cones because they are scarce in the turtle retina and of smaller dimensions compared to the other cone types. In this paper, flash sensitivity action spectra and photoresponses of seven turtle S-cones were measured in the dark-adapted state and during chromatic background illuminations. The desensitizing action of monochromatic background lights was not uniform across the visible spectrum. A red background was most effective in desensitizing the S-cones to long-wavelength stimuli while a blue background light produced its strongest action on the photoresponses elicited by short-wavelength stimuli. The effects of chromatic adaptation on the S-cone action spectrum and on the kinetics of the small-amplitude photoresponses suggested that the S-cones in the turtle retina were involved in complex neural interactions. These included excitatory inputs probably originating in neighboring L-cones and inhibitory long-wavelength inputs probably mediated by L-type horizontal cells.     

Similar properties of cGMP-activated channels between cones and rods in the carp retina.

Using patch-clamp techniques, properties of cGMP-activated channel were studied at a single-channel level in order to examine (1) whether any differences are recognized between the cGMP-activated channels of rods and cones in the same animal species, and (2) whether the channel properties of the same photoreceptor class differ in different animal species. Experiments were performed on inside-out membrane patches excised from outer segments of rods and morphological subtypes of cones in the carp retina. Single-channel activities could be recorded when the patches were perfused with low concentrations of cGMP (less than 10 microM). Throughout five morphological subtypes of cones and rod, single-channel currents showed no significant rectification at membrane hyperpolarization in a low divalent cation solution, and single-channel conductances were almost the same: 13.8 +/- 0.2 pS (mean +/- S.E.M., n = 23) in cones and 12.7 +/- 0.8 pS (n = 3) in rods. These values were significantly smaller than that reported in catfish cones (about 50 pS), and that in rods of the toad and the tiger salamander (about 25 pS). In rods and all subtypes of cones of the carp, open durations of cGMP-activated channels were brief. In addition, kinetic parameters of channel openings and closings showed no differences throughout all subtypes of cones and rod.     

Small-angle light scattering and birefringence properties of chick cornea

PURPOSE: Techniques employing polarized light propagation and scattering are useful in examining the cornea's lamellar structure. Recent advances in theoretical methods have significantly increased the ability to relate features of lamellar arrangements to measurements of transmitted polarized light. The chick cornea, because of its hypothesized structure of a gradual helical rotation of lamellar pairs, presents an interesting model for further development of this methodology. METHODS: Small-angle light scattering (SALS) and polarized transmission measurements were made on 7-week-old chick corneas under conditions that closely approximate the physiological state. Birefringence properties were determined from the transmission measurements and compared to the results of model calculations of polarized light propagating through lamellae organized according to the hypothesized structure for chick cornea. RESULTS: The I+ small-angle light scattering pattern had 4 cloverleaf lobes aligned with the crossed polarizer and analyzer axes. The lobes disappeared when the transcorneal pressure was increased from zero to 18 mmHg. Retardation measured at 18 mmHg was very small (approximately 0.01 microm). CONCLUSION: The disappearance of the I+ small-angle light scattering pattern when IOP is increased suggests that the lamellae undulate in their relaxed state and the undulations straighten when IOP is increased. Measured birefringence properties are consistent with the hypothesized lamellar structure.     

Ionochromic properties of long-wave-sensitive cones in the goldfish retina: an electrophysiological and microspectrophotometric study

Long-wave-sensitive (LWS) cone visual pigments are sensitive to the concentration of chloride ions and show a spectral shift to shorter wavelengths when exposed to low chloride levels. We have used the aspartate-isolated mass receptor potential of the electroretinogram (ERG) to establish whether the spectrally shifted cone pigment is functional. In the goldfish, Carassius auratus, the lambda(max) of the LWS porphyropsin is displaced from about 622 nm to around 606 nm when chloride is replaced by gluconate. The electrical response of the LWS cones (but not MWS cones and rods) is selectively and reversibly abolished by the removal of chloride ions. The effect is concentration dependent and a decrease to half the normal chloride ion concentration is sufficient to cause a decrease in the response.     

The ratio of L cones to M cones in the human parafoveal retina.

We present psychophysically-based estimates of the relative numbers of long-wavelength-sensitive (L) and middle-wavelength-sensitive (M) cones in the parafovea of three color-normal trichromats. Using methods previously applied to the fovea centralis, we obtained estimates of the relative numbers of L and M cones at retinal eccentricities of 1.0, 1.5, 2.0, 3.0, and 4.0 deg along the horizontal meridian of the temporal retina. Results for three observers indicate that the L to M cone ratio remains approximately invariant from the fovea to 4.0 deg eccentricity, with a mean ratio near 2:1.