Objective To observe the pathological and functional changes of retinal photochemical damages exposed to green flurescent light. Methods The Sprague Dawley rats were continually exposed to green fluorescent light with an illuminancem level of (1 900plusmn;106.9) Lx for 24 hours.The changes of retinal morphology and morphometrics and flash electroretinogram were studied before light exposure and at the 6th hour,6th day and 14th day after light exposure. Results At the 6th hours after light exposure,the outer nuclear layer(ONL)of retina becoma thinner compared with that bfore light exposure.The thickness of ONL decreased by 23.91% and the inner and outer segments appeared disorderly arranged.At the 6th day after light exposure the thickness of ONL is thinner than that at the6th hour,i.e.decreased by 46.6%. At the 14th day after light exposure the thickness of ONL decreased by 42.40%.Flash electroretinogram showed that the amplitudes of a and b wave decreased continuously at the 6th hour and 6th day and unrecovered at the 14th day after light exposure. Conclusion This model might be an ideal one for research on retinal photochemical damage. (Chin J Ocul Fundus Dis,1998,14:101-103)
Objective To study the response of the retinal neuronal adaptive system to changes of background illumination (BG) by measuring the oscillatory potentials (OPs) and the a- and b-waves of the electroretinogram (ERG) in different BG illuminations. Methods The a- and b-wave and the digitally filtered OPs were simultaneously recorded from Wistar Fu rats aged from 25 to 29 days during dark adaptation (DA) and during 6~8 minutes of BG illuminations at four levels increased successively by steps of two log units, i.e., ldquo;low scotopicrdquo; level of 1.43times;10-6cd/m2, ldquo;high scotopicrdquo; of 1.43times;10-4cd/m2 , ldquo;low mesopicrdquo; of 1.43times;10-2cd/m2 and ldquo;high mesopicrdquo; of 1.43times;10-2cd/m2. Full field stimulus flashes of 75 msec duration and 1.43times;10-2cd/m2intensity was delivered at an interval of 1 minute. Results Five OP wavelets were recorded in DA and during scotopic BG illuminations. The number of wavelets was reduced to three as the eyes were exposed to mesopic BG levels. However, the sum of OPs amplitudes (SOPs) increased as the BG was intensified, except at ldquo;high mesopicrdquo; level, by which a significant decrease of SOPs occurred. The amplitudes of the a-and b-waves remained unchanged at the two scotopic BG and decreased as the BG intensity increased to mesopic levels. Conclusion The response of retinal neural adaptive system of the Albino rat to changes of BG light is more sensitive and robust than the slow components of the ERG. The enhancement of the oscillatory responses at ldquo;low mesopicrdquo; illumination level suggests that using proper BG light may be conducive to reducing the variation of OPs. (Chin J Ocul Fundus Dis, 2001,17:286-288)
Objective To observe the effect of visible light on apoptosis of cultured human retinal pigment epithelium (RPE) cells. Methods Being the light source,500lx,(2 000±500)lx and (3 400±200)lx cold white light were used. The duration of exposure was 0,6,12 and 24 hours respectively. Apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labelling, Annexin V-flunorescein isothiocyanate/Propidium iodium labelling and flow cytometry. Results Apoptosis and necrosis were found in cultured human RPE cells which were exposed to visible light.(1)A significant increase in apoptotic and necrotic percentages was consistent with a higher light intensity.(2)Apoptosis was the main response to shorter (6 h and 12 h) exposure duration,while necrosis was more pronounced correlated to the prolongation of post-exposure culture (P＜0.05),and the longer the post-exposure period was, the more apoptotic necrosis were seen.Thirty-six hours after exposure the necrotic percentages were more pronounced (P＜0.01). Conclusions Visible light (＞500 lx) increases the proportion of apoptosis and necrosis of human RPE cells in vitro.The extent is related to exposure intensity and duration. It demonstrates that the lower intensity and the shorter duration of exposure to light are, the more pronounced apoptotic percentages are observed,otherwise necrosis. (Chin J Ocul Fundus Dis, 2002, 18: 227-230)
Photosensitive occipital lobe epilepsy (POLE) is a rare idiopathic reflex focal epilepsy that can occur in all age groups. It is characterized by occipital lobe seizures induced by flashing stimuli (flashing sunlight, video games, TV commercials and programs, etc.). Photoparoxysmal response on EEG is induced by intermittent photic stimulation; Ictal EEG shows rapid spike rhythms are originated from the occipital region. There are no obvious abnormalities in brain image. POLE responds well to anti-seizure medications and has a good prognosis. This article reviews the research progress on POLE in order to improve the clinician’s understanding and reduce the rates of missed diagnosis and misdiagnosis.
In order to solve the problems that the injury, hemorrhage, infection and edema of the brain tissue caused by brain electrodes implantation for aquatic animal robots, a light stimulation device and an optical control experiment method for carp robots are proposed in this paper. According to the shape of the carp skull, the device is a structure of Chinese character " 王” cut by a printed circuit board which can provide three groups of A, B and C bridge platforms for the light stimulation source. The two ends of a bridge in every group are welded with a jumper board, and the light emitting diodes (LED) are inserted into the jumper boards as the light stimulation source, and all negative poles of the jumper boards are connected to the console by the wire. A LED light can be replaced by another LED light according to the need of the wavelength of the LED light, and various combinations of the light stimulation modes can be also selected. This device was mounted on the carp robot’s head, the carp robot was placed in a water maze, and the optical control experiment method was observed to control the forward movement and steering movement of the carp robots (n = 10) under the dark light condition. The results showed that the success rates of the three groups of red light control experiments were 53%–87%, and the success rates of the three groups of blue light control experiments were 50%–80%. This study shows that the apparatus and the method are feasible.
ObjectiveTo observe the influence of down-regulation of HtrA1 expression by small interfering RNA on light-injured human retinal pigment epithelium (RPE) cells. MethodsCultured human RPE cells(8th-12th generations)were exposed to the blue light at the intensity of (2000±500) Lux for 6 hours to establish the light injured model. Light injured cells were divided into HtrA1 siRNA group, negative control group and blank control group. HtrA1 siRNA group and negative control group were transfected with HtrA1 siRNA and control siRNA respectively. The proliferation of cells was assayed by CCK-8 method. Transwell test was used to detect the invasion ability of these three groups. Flow cytometry was used to detect the cell cycle and apoptosis. The expression of HtrA1 and vascular endothelial growth factor (VEGF)-A was detected by real time-polymerase chain reaction and Western blot respectively. ResultsThe mRNA and protein level of HtrA1 in the light injured cells increased significantly compared to that in normal RPE cells (t=17.62, 15.09; P<0.05). Compared with negative control group and blank control group, the knockdown of HtrA1 in HtrA1 siRNA group was associated with reduced cellular proliferation (t=6.37, 4.52), migration (t=9.56, 12.13), apoptosis (t=23.37, 29.08) and decreased mRNA (t=17.36, 11.32, 7.29, 4.05) and protein levels (t=12.02, 15.28, 4.98, 6.24) of HtrA1 and VEGF-A. Cells of HtrA1 siRNA group mainly remained in G0/G1 phase, the difference was statistically significant (t=6.24, 4.93; P<0.05). ConclusionKnockdown of HtrA1 gene may reduce the proliferation, migration capability and apoptosis of light-injured RPE cells, and decrease the expression of VEGF-A.
Objective To investigate the effect of blue light on mRNA expression of L-type calcium channel subtypes of human retinal pigment epithelial (RPE) cells in vitro. Methods The fourth-generation of human RPE cells were randomly divided into four groups including control group (no light group), light group, light + nifedipine group, and light + (-) BayK8644 group. The cells were exposed to blue light (2000plusmn;500) lux for 6 hours, and then cultured for another 24 hours. Reverse transcription polymerase chain reaction real time (RT-PCR) and fluorescence quantitative PCR technologies were used to analyze mRNA expression of L-type calcium channel subunit of cardiac subtype ( 1C or CaV1.2), neuroendocrine subtype ( 1D or CaV1.3) and retinal subtypes ( 1F or CaV1.4) in each group. Results The length of PCR product of 1C, 1D, 1F subunit and actin was 68, 157, 125 and 186 base pairs respectively. (1) 1C mRNA expression in light, light + nifedipine and light + (-) BayK8644 group was higher than that in control group, the difference was statistically significant (P＜0.05). 1C mRNA expression in light +nifedipine group and light + (-) BayK8644 group was higher than in light group (P＜0.05). 1C mRNA expression in light + (-) BayK8644 group was higher than that in light + nifedipine group (P＜0.05). (2) Comparing with control group, 1D mRNA expression was higher in light, light +nifedipine and light + (-) BayK8644 group, the difference was statistically significant (P＜0.05). Light + (-) BayK8644 group was higher than light group and light + nifedipine group (P＜0.05), light group and the light + nifedipine group was not statistically significant (P＞0.05). (3) 1F mRNA expression in light, light + nifedipine and light + (-) BayK8644 group was higher than those in control group, there was statistically significant (P＜0.05), light +nifedipine group and light + (-) BayK8644 group was higher than light group (P＜0.05), light + nifedipine group and the light + (-) BayK8644 group was not statistically significant (P＞0.05). Conclusions The human RPE cells mRNA expression of L-type calcium channel 1C, 1D and 1F subunit was increased after exposing to blue light. Application of the 1times;10-5 mmol/L (-) BayK8644 can increase mRNA expression of 1C, 1D and 1F subunit.
Objective To further investigate pathologic mechanism of retinal phototrauma. Methods Twenty Wistar rats were divided into control and experimental groups.Their eyes were extracted in 12，24 and 36 hours after light exposure.HE stained retina samples were examined and TDT-mediated dUTP nick end labelling(TUNEL)method was employed to distinguish apoptotic cells. Results After 12-hour light exposure,slight vesiculation was observed in the rod outer segment of the retinas.After 24-hour light exposure,the outer nuclear layer showed predominant fractured and condensed nuclei and fragmented DNA.After 36-hour light exposure,the rod outer and inner segments were lysed and most of the nuclei in the outer nuclear layer were disappeared. Conclusions Apoptosis of photoreceptor cell is one of the important mechanisms which cause experimental retinal photoinjury of rats. (Chin J Ocul Fundus Dis, 1999, 15: 167-169)
ObjectiveTo investigate the effects of FTY720 on retinal photoreceptor cells and microglial following light-induced degeneration in rat retina. Methods120 Sprague-Dawley rats were randomly divided into four groups including FTY720 group, solvent control group, model group and normal group. The rats of normal group were not intervened. The FTY720 group, solvent control group and model group establish retinal light injury mode. FTY720 was injected into abdominal cavity of the rats in FTY720 group 0.5 hours before light exposure. 50% dimethylsulfoxide was injected into abdominal cavity of the rats in solvent control group. The expressions of microglial cells in rat retinal were quantified using flow cytometry, the expressions of interleukin (IL)-1βwere examined by enzyme-linked immuno sorbent assay at 6 hours, 1 day, 3 days, 7 days after light exposure. The apoptosis of retinal photoreceptor cells were measured by terminal-deoxynucleoitidyl transferase mediated nick end labeling at 1 day after light exposure. The morphological change of retinal were viewed by haematoxylin and eosin staining at 7 days after light exposure. ResultsThe expressions of microgilal and IL-1βbegan to rise at 1 day after light exposure, reached at peak at 3 days and decreased at 7 days. The expressions of IL-1βand microglial in FTY720 group were significantly lower than solvent control group and model group, but higher than normal group (P < 0.05).One day after exposure to light, the apoptosis cell ratio in normal group, model group, solvent control group and FTY720 group were 0, (87.66±2.50)%, (86.00±2.44)%, (49.66±2.80)%. The apoptosis cell in FTY720 group were higher than normal group, lower than solvent control group and model group (P < 0.05). Seven days after exposure to light, the retinal in normal group was structured and the cell was arranged well, the cell in solvent control group and model group was irregular arrangement and the outer nuclear layer (ONL) was thin after light exposure. The thickness of the ONL in FTY720 group was significantly higher than solvent control group and model group, below normal group. ConclusionFTY720 can prevents retinal photoreceptor cells from apoptosis and inhibits activation of microglial.