RESUMEN
CNS neurons change their connectivity to accommodate a changing environment, form memories, or respond to injury. Plasticity in the adult mammalian retina after injury or disease was thought to be limited to restructuring resulting in abnormal retinal anatomy and function. Here we report that neurons in the mammalian retina change their connectivity and restore normal retinal anatomy and function after injury. Patches of photoreceptors in the rabbit retina were destroyed by selective laser photocoagulation, leaving retinal inner neurons (bipolar, amacrine, horizontal, ganglion cells) intact. Photoreceptors located outside of the damaged zone migrated to make new functional connections with deafferented bipolar cells located inside the lesion. The new connections restored ON and OFF responses in deafferented ganglion cells. This finding extends the previously perceived limits of restorative plasticity in the adult retina and allows for new approaches to retinal laser therapy free of current detrimental side effects such as scotomata and scarring.
Asunto(s)
Rayos Láser/efectos adversos , Fotocoagulación/métodos , Recuperación de la Función/fisiología , Retina/patología , Enfermedades de la Retina/cirugía , Animales , Modelos Animales de Enfermedad , Estimulación Eléctrica , Ácido Glutámico/metabolismo , Técnicas In Vitro , Masculino , Técnicas de Placa-Clamp , Estimulación Luminosa , Células Fotorreceptoras/patología , Células Fotorreceptoras/ultraestructura , Conejos , Retina/metabolismo , Retina/ultraestructura , Enfermedades de la Retina/etiología , Células Ganglionares de la Retina/fisiología , Sinapsis/patología , Sinapsis/ultraestructura , Factores de Tiempo , Tomografía Computarizada por Rayos X , Visión Ocular/fisiología , Vías Visuales/patología , Vías Visuales/fisiología , Ácido gamma-Aminobutírico/metabolismoRESUMEN
PURPOSE: To evaluate the effect of intravitreal triamcinolone acetonide (TA) on healing of retinal photocoagulation lesions using drug and laser dosing typically employed in clinical practice. METHODS: Laser burns with a 267-µm retinal beam size at 532-nm wavelength were applied to 40 eyes of Dutch belted rabbits. Barely visible to intense lesions were produced with pulses of 5, 10, 20, and 50 milliseconds and power of 175 mW. Eyes received intravitreal injections of either 2 mg TA/50 µL or balanced salt solution administered either 1 week before or immediately after laser treatment. Lesion grades were assessed acutely ophthalmoscopically and by a masked observer histologically at 1, 3, 7, 30, and 60 days. RESULTS: Both TA groups demonstrated significant reduction in retinal thickness throughout follow-up compared with balanced salt solution groups (P < 0.001). The width of the lesions at 1 day after injection was not significantly different between groups. However, by 7 days, the lesions in balanced salt solution groups contracted much more than in the TA groups, especially the more intense burns, and this difference persisted to 2 months. The healing rate of the barely visible burns was not significantly affected by TA compared with the balanced salt solution control eyes. CONCLUSION: Triamcinolone acetonide injection previously or concurrently with photocoagulation significantly decreases laser-induced edema but interferes with lesions healing, thereby leaving wider residual scarring, especially persistent in more intense burns.
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Glucocorticoides/uso terapéutico , Coagulación con Láser/efectos adversos , Papiledema/tratamiento farmacológico , Retina/cirugía , Triamcinolona Acetonida/uso terapéutico , Cicatrización de Heridas/efectos de los fármacos , Acetatos/uso terapéutico , Animales , Combinación de Medicamentos , Inyecciones Intravítreas , Minerales/uso terapéutico , Papiledema/etiología , Papiledema/patología , Conejos , Retina/fisiología , Cloruro de Sodio/uso terapéuticoRESUMEN
PURPOSE: To evaluate the subfoveal choroidal thickness (SCT) of the epiretinal membrane (ERM) and macular hole (MH) both before and after microincision vitrectomy surgery. SUBJECTS AND METHODS: A total of 104 eyes of 104 subjects (64 ERM, 40 MH, mean age 68.9 years) were evaluated. All subjects underwent vitrectomy with internal limiting membrane peeling. SCT was measured before vitrectomy and 1 week, 1 month and 3 months postoperatively. SCT was measured by enhanced depth imaging OCT (EDI-OCT) using a Heiderberg Spectralis. RESULTS: The SCT of ERM was 202.6 microm before vitrectomy, and 201.8 microm at 1 week, 198.8 microm at 1 month, and 196.4 microm at 3 months postoperatively. There were no significant differences between the times of measurement. MH was 182.5 microm before vitrectomy, and 186.7 microm at 1 week, 189.4 microm at 1 month, and 187.4 microm at 3 months. There were also no significant differences between any other factors. The SCT between the ERM and MH was not significantly different at any time. We examined the correlation between the changes in SCT and the changes in age, refractive error and intraocular pressure (IOP), but found no significant correlation. CONCLUSION: The SCT hat not changed either before or after microincision vitrectomy surgery, and there was no siginificant correlation between SCT and any other factor.
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Membrana Epirretinal/patología , Perforaciones de la Retina/patología , Vitrectomía/métodos , Anciano , Anciano de 80 o más Años , Membrana Epirretinal/cirugía , Ojo/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Periodo Posoperatorio , Perforaciones de la Retina/cirugía , Tomografía de Coherencia Óptica/métodos , Resultado del Tratamiento , Agudeza Visual/fisiologíaRESUMEN
The distribution of the collagen chains from α1(IV) to α6(IV) could serve as a basis for the characterization of type IV collagen. In this study, immunohistochemistry of the ocular anterior segment of adult mice was performed using specific monoclonal antibodies against each chain in the series from α1(IV) to α6(IV). The results show that the components of type IV collagen in vascular basement membranes are α1(IV) and α2(IV) with or without α5(IV) and α6(IV) chains and those in epithelium and muscle basement membranes are α1(IV), α2(IV), α5(IV), and α6(IV) chains. In corneal endothelium, pigmented epithelium of iris and ciliary body, and trabecular meshwork, α3(IV) and α4(IV) chains are also expressed in addition to α1(IV), α2(IV), α5(IV), and α6(IV) chains. Moreover, we investigated the change in molecular composition in ciliary body during postnatal development. α3(IV) and α4(IV) chains were also expressed in addition to α1(IV), α2(IV), α5(IV), and α6(IV) chains in ciliary pigmented epithelium basement membrane from 7 days after birth. This result suggests that the basement membranes gradually change their biochemical features owing to temporal regulation. Taken together, these findings suggest that the different distribution and the developmental expression of α1(IV) to α6(IV) chains are associated with the tissue-specific function of type IV collagen in basement membranes.
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Membrana Basal/metabolismo , Colágeno Tipo IV/metabolismo , Ojo/metabolismo , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales , Cuerpo Ciliar/metabolismo , Endotelio/metabolismo , Ensayo de Inmunoadsorción Enzimática , Epitelio/metabolismo , Ojo/crecimiento & desarrollo , Inmunohistoquímica , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Péptidos/genéticaRESUMEN
PURPOSE: To evaluate the safety, selectivity, and healing of retinal lesions created using a continuous line scanning laser. METHODS: A 532-nm Nd:YAG laser (PASCAL) with retinal beam diameters of 40 µm and 66 µm was applied to 60 eyes of 30 Dutch-belted rabbits. Retinal exposure duration varied from 15 µs to 60 µs. Lesions were acutely assessed by ophthalmoscopy and fluorescein angiography. Retinal pigment epithelial (RPE) flatmounts were evaluated with live-dead fluorescent assay. Histological analysis was performed at 7 time points from 1 hour to 2 months. RESULTS: The ratios of the threshold of rupture and of ophthalmoscopic visibility to fluorescein angiography visibility (measures of safety and selectivity) increased with decreasing duration and beam diameter. Fluorescein angiography and live-dead fluorescent assay yielded similar thresholds of RPE damage. Above the ophthalmoscopic visibility threshold, histology showed focal RPE damage and photoreceptor loss at 1 day, without inner retinal effects. By 1 week, photoreceptor and RPE continuity was restored. By 1 month, photoreceptors appeared normal. CONCLUSION: : Retinal therapy with a fast scanning continuous laser achieves selective targeting of the RPE and, at higher power, of the photoreceptors without permanent scarring or inner retinal damage. Continuous scanning laser can treat large retinal areas within standard eye fixation time.
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Coagulación con Láser/instrumentación , Coagulación con Láser/métodos , Láseres de Estado Sólido , Retina/cirugía , Epitelio Pigmentado de la Retina/cirugía , Animales , Angiografía con Fluoresceína , Oftalmoscopía , Conejos , Retina/patología , Epitelio Pigmentado de la Retina/patología , Cicatrización de HeridasRESUMEN
Glutamine derivative 1 with two-photon absorbing units has been synthesized and was found to show gelation ability in some solvents. Its self-assembly in the gel phase could be controlled by the solvent and speed of gelation. For example, in DMSO the organogelator self-assembled into H-aggregates with weak exciton coupling between the aromatic moieties. On the other hand, in DMSO/diphenyl ether (1:9, v/v) the molecules formed 1D aggregates, but with strong exciton coupling due to the small distance between the chromophores. Moreover, the formation of these two kinds of aggregates could be adjusted by the ratio of DMSO to diphenyl ether. In DMSO/toluene, DMSO/butanol, DMSO/butyl acetate, and DMSO/acetic acid systems similar results were observed. Therefore, conversion of the packing model occurs irrespective of the nature of the solvent. Notably, a unique sign inversion in the CD spectra could be realized by controlling the speed of gelation in the DMSO/diphenyl ether (1:9, v/v) system. It was found that a low speed of gelation induces the gelator to adopt a packing model with strong pi-pi interactions between the aromatic units. Moreover, the gels, when excited at 800 nm, emit strong green fluorescence and the quantum chemical calculations suggest that intramolecular charge transfer leads to two-photon absorption of the gelator molecule.
Asunto(s)
Geles/química , Glutamina/química , Solventes/química , Dimetilsulfóxido/química , Cinética , Espectrofotometría Ultravioleta , Estereoisomerismo , TemperaturaRESUMEN
In laser retinal photocoagulation, short (<20 ms) pulses have been found to reduce thermal damage to the inner retina, decrease treatment time, and minimize pain. However, the safe therapeutic window (defined as the ratio of power for producing a rupture to that of mild coagulation) decreases with shorter exposures. To quantify the extent of retinal heating and maximize the therapeutic window, a computational model of millisecond retinal photocoagulation and rupture was developed. Optical attenuation of 532-nm laser light in ocular tissues was measured, including retinal pigment epithelial (RPE) pigmentation and cell-size variability. Threshold powers for vaporization and RPE damage were measured with pulse durations ranging from 1 to 200 ms. A finite element model of retinal heating inferred that vaporization (rupture) takes place at 180-190 degrees C. RPE damage was accurately described by the Arrhenius model with activation energy of 340 kJ/mol. Computed photocoagulation lesion width increased logarithmically with pulse duration, in agreement with histological findings. The model will allow for the optimization of beam parameters to increase the width of the therapeutic window for short exposures.
Asunto(s)
Coagulación con Láser/métodos , Modelos Biológicos , Retina/diagnóstico por imagen , Enfermedades de la Retina/cirugía , Animales , Supervivencia Celular , Simulación por Computador , Análisis de Elementos Finitos , Calor , Coagulación con Láser/efectos adversos , Terapia por Láser , Conejos , Retina/lesiones , Epitelio Pigmentado de la Retina/lesiones , Epitelio Pigmentado de la Retina/patología , Porcinos , Termodinámica , UltrasonografíaRESUMEN
PURPOSE: To characterize the in vitro behavior of three preparations of triamcinolone acetonide (TA). METHODS: Three preparations of TA were mixed with Balanced Salt Solution Plus: commercially available TA (Kenalog 40, Bristol-Myers Squibb, Princeton, NJ), compounded preservative-free triamcinolone acetonide (PFTA, New England Compounding Center, Framingham, MA), and triamcinolone acetonide injectable suspension (TAIS, TRIESENCE, Alcon, Inc., Fort Worth, TX). We determined the mean number of crystalline aggregates per high-power deconvolution microscopy field, largest aggregate area, and spectroscopic photometric absorption. RESULTS: Preservative-free triamcinolone acetonide had larger mean number of aggregates compared with TA (time 0 P = 0.002, 10 minutes P < 0.001) and TAIS (time 0 P < 0.001, 10 minutes P = 0.003). Aggregate size varied at both 0 and 10 minutes: TAIS > TA > PFTA. Spectroscopic photometric absorption decreased in direct correlation to aggregate size over time for all three preparations. CONCLUSION: In vitro, PFTA in Balanced Salt Solution Plus had more aggregates of smaller size than either TA or TAIS. By contrast, TAIS had much larger aggregate size than both PFTA and TA, and this increased over time. These findings correlate with the clinical observations that PFTA and TA tend to disperse throughout the vitreous, whereas TAIS tends to conglomerate and gravitate toward the most dependent portion of the eye in a globular fashion.
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Glucocorticoides/química , Triamcinolona Acetonida/química , Cristalización , Procesamiento de Imagen Asistido por Computador , Técnicas In Vitro , Microscopía , Soluciones Oftálmicas/química , Conservadores Farmacéuticos , EspectrofotometríaRESUMEN
To synthesize composite solid materials of metal salt and CdSe nanocrystals by a simple one-step method has been described. These solids can form stable gel in some organic solvent, such as benzene, cyclohexane and 1-butanol, especial in n-decane even below 0.1 wt/vol.%. Furthermore, these gels appear strong fluorescence which can be easily adjusted by the gel concentration. Temperature-dependent fluorescence spectra of composite gels suggested that the CdSe NCs aggregate together in gel state which would induce the energy transfer between nanocrystals and these aggregates could be reversibly disintegrated when gel was heated to form sol. TEM observations provided the further evidence of the energy transfer and suggested that the CdSe NCs were enchased regularly not only on the surface of self assembly of metal salt, but also embedded inside of self assembly in composite gel with small size nanocrystals. In contrast, in composite organogel with large nanocrystals they were only enchased on the edge of self assembly.
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Membrana Basal/patología , Colorantes , Membrana Epirretinal/cirugía , Verde de Indocianina , Perforaciones de la Retina/cirugía , Colorantes de Rosanilina , Anciano , Anciano de 80 o más Años , Extracción de Catarata , Colorantes/efectos adversos , Membrana Epirretinal/diagnóstico , Membrana Epirretinal/fisiopatología , Femenino , Humanos , Indicadores y Reactivos , Verde de Indocianina/efectos adversos , Masculino , Persona de Mediana Edad , Pronóstico , Perforaciones de la Retina/diagnóstico , Perforaciones de la Retina/fisiopatología , Estudios Retrospectivos , Colorantes de Rosanilina/efectos adversos , Tomografía de Coherencia Óptica , Agudeza Visual/fisiología , VitrectomíaRESUMEN
PURPOSE: To evaluate the anatomic and functional outcomes of pars plana vitrectomy combined with internal limiting membrane peeling for recurrent macular edema (ME) due to branch retinal vein occlusion (BRVO) after intravitreal injections of antivascular endothelial growth factor (anti-VEGF) agents. METHODS: Twenty-four eyes of 24 patients with treatment-naive ME from BRVO were treated with intravitreal injections of anti-VEGF agents. Recurred ME was treated with pars plana vitrectomy combined with internal limiting membrane peeling. RESULTS: After the surgery, ME was significantly reduced at 1 month (P=0.031) and the reduction increased with time (P=0.007 at the final visit). With the reduction in ME, treated eyes showed a slow improvement in visual acuity (VA). At the final visit, improvement in VA was statistically significant compared with baseline (P=0.048). The initial presence of cystoid spaces, serous retinal detachment, or subretinal hemorrhage under the fovea, as well as retinal perfusion status, showed no association with VA improvement. However, the presence of epiretinal membrane showed a significant association with the visual recovery. Although eyes without epiretinal membrane showed visual improvement (-0.10±0.32 in logarithm of the minimum angle of resolution [logMAR]), eyes with epiretinal membrane showed greater visual improvement (-0.38±0.12 in logMAR, P=0.012). CONCLUSION: For recurrent ME due to BRVO after anti-VEGF treatment, particularly when accompanied by epiretinal membrane, pars plana vitrectomy combined with internal limiting membrane peeling might be a possible treatment option.
RESUMEN
BACKGROUND AND OBJECTIVE: To characterize the cellular, immunological, and inflammatory response to retinal photocoagulation of intense rupture laser lesions as a model of retinal degenerative diseases. MATERIALS AND METHODS: Seven C57BL/6 mice were irradiated using a 532-nm laser to induce 10 retinal burns per eye that ruptured Bruch's membrane. Blood was drawn from the saphenous vein before and 2 months after laser treatment. The serum was run on antigen microarrays with 85 molecular markers associated with retinal degenerative diseases. RESULTS: Rupture laser resulted in dramatic changes in the immunoglobulin reactivity of most inflammatory markers 2 months after laser injury. Approximately two-thirds increased expression and one-third decreased expression. Notable markers that were increased included complement C3, CRP, PKM2, and aldolase. CONCLUSION: Rupture laser injury causes a change in the serum inflammatory markers after 2 months similar to macular degeneration, diabetic retinopathy, and cancer-associated retinopathy. This animal model could be used as a biomarker for disease stage and activity in retinal degenerations.
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Biomarcadores/sangre , Lámina Basal de la Coroides/lesiones , Modelos Animales de Enfermedad , Coagulación con Láser/efectos adversos , Degeneración Retiniana/sangre , Animales , Proteína C-Reactiva/metabolismo , Complemento C3/metabolismo , Fructosa-Bifosfato Aldolasa/sangre , Inmunoglobulina G/sangre , Inflamación , Ratones , Ratones Endogámicos C57BL , Piruvato Quinasa/sangre , Degeneración Retiniana/etiología , Degeneración Retiniana/patología , Rotura , Vena SafenaRESUMEN
A novel oligodendrocyte (OL)-specific cDNA was isolated from brain capillary endothelial cells and characterized. The cDNA encodes a protein of 1099 amino acids that contains a signal peptide and a transmembrane domain. The protein was expressed in mature OLs in vivo and in vitro cell cultures and was thus designated as mature OL transmembrane protein (MOLT). RT-PCR analysis showed that MOLT mRNA was expressed in brain, lung, pancreas, and testis. A polyclonal antibody raised against a part of the mouse MOLT reacted specifically with multipolar OLs possessing radially oriented processes that penetrated into the gray matter. More cells were detected in the white matter, and these had longitudinally oriented processes. In a rat OL lineage culture system, oligodendrocyte precursor cells did not initially produce MOLT mRNA and protein, but when they begun to differentiate into mature OLs, they started expressing MOLT. Consequently, MOLT may function as OLs become mature and may serve as a cell-surface marker for OL differentiation.
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Proteínas de la Membrana/biosíntesis , Proteínas de la Membrana/genética , Proteínas del Tejido Nervioso/biosíntesis , Proteínas del Tejido Nervioso/genética , Oligodendroglía/metabolismo , Secuencia de Aminoácidos , Animales , Encéfalo/irrigación sanguínea , Encéfalo/metabolismo , Células COS , Diferenciación Celular/fisiología , Linaje de la Célula , Células Cultivadas , Chlorocebus aethiops , Clonación Molecular , ADN Complementario/genética , ADN Complementario/aislamiento & purificación , Endotelio Vascular/química , Endotelio Vascular/metabolismo , Humanos , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Oligodendroglía/citología , Señales de Clasificación de Proteína/fisiología , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Ratas , Homología de Secuencia de AminoácidoRESUMEN
PURPOSE: To evaluate the effects of radial optic neurotomy (RON) on retinal circulation in patients with central retinal vein occlusion (CRVO) by indocyanine green (ICG) videoangiography and a computer-assisted image analysis. DESIGN: An interventional case series. METHODS: RON was performed in 15 eyes of 15 patients with CRVO. Within 72 hours before the surgery and at 3 months after the surgery, ICG videoangiography was performed with a scanning laser ophthalmoscope, and the images were transferred to a computer. Two measurement points were selected, one on a main retinal artery close to the optic disk and the other on the corresponding retinal vein. At each point, fluorescence intensities were serially measured, and dye dilution curves were obtained. Retinal circulation times (DeltaT(50)) before and after the surgery were calculated. RESULTS: Mean preoperative DeltaT(50) was 6.46 +/- 1.36 seconds, and mean postoperative DeltaT(50) was 6.80 +/- 2.50 seconds. In 8 of 15 eyes, T(50) decreased by 6.8% to 29.6% after the surgery. In the seven eyes that developed chorioretinal anastomosis (CRA) at the site of RON, DeltaT(50) decreased after the surgery. In contrast, DeltaT(50) decreased postoperatively in only one of the eight eyes without CRA. Best-corrected visual acuity improved significantly after the surgery in the group of eyes with improvement in DeltaT(50), but not in the group of eyes without improvement in DeltaT(50). CONCLUSIONS: Some degree of retinal circulation improvement occurred in approximately half of these eyes, which appears to be correlated with the development of CRA.
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Colorantes , Angiografía con Fluoresceína/métodos , Verde de Indocianina , Nervio Óptico/cirugía , Oclusión de la Vena Retiniana/cirugía , Anciano , Circulación Sanguínea , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Persona de Mediana Edad , Disco Óptico/irrigación sanguínea , Oclusión de la Vena Retiniana/diagnóstico , Oclusión de la Vena Retiniana/fisiopatología , Vasos Retinianos/fisiopatologíaRESUMEN
We herein determined by fluorescence in situ hybridization the chromosomal localization of 2 human genes, BRAL1 and BCAN, both of which belong to the link-module superfamily, i.e. to the same band of chromosome 1q21-23. Further analysis of the genomic organization of BRAL1 and BCAN revealed that the BRAL1 gene was located 20-kb upstream of the BCAN start site. We isolated a polymorphic dinucleotide (CA) repeat sequence from a genomic clone containing the BCAN gene. High heterozygosity (0.79) makes this polymorphism a useful marker in the study of genetic disorders. Knowledge of the structure of the genes and the marker provides essential information for further analysis of the gene locus at chromosome 1q21-23.
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Cromosomas Humanos Par 1 , Proteínas del Tejido Nervioso/genética , Proteoglicanos/genética , Brevicano , Proteoglicanos Tipo Condroitín Sulfato/genética , Mapeo Cromosómico , Repeticiones de Dinucleótido , Ligamiento Genético , Humanos , Hibridación Fluorescente in Situ , Lectinas Tipo C , Familia de Multigenes/genética , Polimorfismo GenéticoRESUMEN
PURPOSE: To evaluate the stability of axis rotation, astigmatism correction, and improvement in uncorrected distance visual acuity (UDVA) up to 6 months postoperatively using an astigmatism-correcting intraocular lens (IOL) in a 25-gauge transconjunctival sutureless vitrectomy combined with cataract surgery. SETTING: Department of Ophthalmology, Kagawa University Faculty of Medicine, Kagawa, Japan. DESIGN: Prospective nonrandomized interventional study. METHOD: Eyes with a preoperative corneal cylinder of more than 0.75 diopter (D) had a triple procedure for idiopathic epiretinal membrane (ERM) using an Acrysof IQ toric IOL. Outcome measures were the amount of IOL axis rotation up to 3 months postoperatively, UDVA, corrected distance visual acuity, and corneal and refractive astigmatism up to 6 months postoperatively. A comparison was performed between patients with a target postoperative spherical refraction of emmetropia (toric emmetropic group) and patients who previously had a triple procedure for idiopathic ERM using a nontoric IOL (control group). RESULTS: The mean IOL axis rotation from the end of surgery until 3 months postoperatively was 3.67 degrees ± 3.13 (SD). Six months postoperatively, the mean corneal and refractive cylinders were 1.32 ± 0.61 D and 0.51 ± 0.31 D, respectively, showing a significant difference (P<.0001, paired t test). In addition, the mean UDVA was significantly improved 6 months postoperatively in the control and toric emmetropic group (0.57 logMAR versus 0.35 logMAR) (P=.028), although the toric group was more improved than the control group. CONCLUSION: In vitrectomy (triple procedure) for idiopathic ERM with a toric IOL, postoperative IOL axis stability was similar to that reported for cataract surgery alone. Furthermore, the UDVA was better than with implantation of a spherical IOL.
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Astigmatismo/cirugía , Membrana Epirretinal/cirugía , Lentes Intraoculares , Microcirugia/métodos , Facoemulsificación/métodos , Vitrectomía/métodos , Anciano , Anciano de 80 o más Años , Astigmatismo/fisiopatología , Catarata/fisiopatología , Membrana Epirretinal/diagnóstico , Membrana Epirretinal/fisiopatología , Femenino , Humanos , Implantación de Lentes Intraoculares , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Técnicas de Sutura , Tomografía de Coherencia Óptica , Resultado del Tratamiento , Trastornos de la Visión/fisiopatología , Agudeza Visual/fisiologíaRESUMEN
PURPOSE: Müller glia respond to retinal injury by a reactive gliosis, but only rarely do mammalian glial cells re-enter the cell cycle and generate new neurons. In the nonmammalian retina, however, Müller glia act as stem/progenitor cells. Here, we tested the function of Wnt signaling in the postinjury retina, focusing on its ability to influence mammalian Müller cell dedifferentiation, proliferation, and neurogenesis. METHODS: A 532 nm frequency doubled neodymium-doped yttrium aluminum garnet (ND:YAG) laser was used to create light burns on the retina of Axin2(LacZ/+) Wnt reporter mice. At various time points after injury, retinas were analyzed for evidence of Wnt signaling as well as glial cell response, proliferation, and apoptosis. Laser injuries also were created in Axin2(LacZ/LacZ) mice, and the effect of potentiated Wnt signaling on retinal repair was assessed. RESULTS: A subpopulation of mammalian Müller cells are Wnt responsive and, when Wnt signaling is increased, these cells showed enhanced proliferation in response to injury. In an environment of heightened Wnt signaling, caused by the loss of the Wnt negative regulator Axin2, Müller cells proliferated after injury and adopted the expression patterns of retinal progenitor cells (RPCs). The Wnt-responsive Müller cells also exhibited long-term survival and, in some cases, expressed the rod photoreceptor marker, rhodopsin. CONCLUSIONS: The Wnt pathway is activated by retinal injury, and prolonging the endogenous Wnt signal causes a subset of Müller cells to proliferate and dedifferentiate into RPCs. These data raised the possibility that transient amplification of Wnt signaling after retinal damage may unlock the latent regenerative capacity long speculated to reside in mammalian neural tissues.
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Neuroglía/metabolismo , Retina/lesiones , Proteínas Wnt/metabolismo , Animales , Apoptosis , Ciclo Celular , Diferenciación Celular , Proliferación Celular , Supervivencia Celular , Modelos Animales de Enfermedad , Quemaduras Oculares/metabolismo , Quemaduras Oculares/patología , Láseres de Estado Sólido/efectos adversos , Ratones , Ratones Endogámicos C57BL , Neuroglía/patología , Retina/metabolismo , Retina/patología , Transducción de SeñalRESUMEN
PURPOSE: Subthreshold retinal phototherapy demonstrated clinical efficacy for the treatment of diabetic macular edema without visible signs of retinal damage. To assess the range of cellular responses to sublethal hyperthermia, expression of the gene encoding a 70 kDa heat shock protein (HSP70) was evaluated after laser irradiation using a transgenic reporter mouse. METHODS: One hundred millisecond, 532 nm laser exposures with 400 µm beam diameter were applied to the retina surrounding the optic nerve in 32 mice. Transcription from the HSP70 promoter was assessed relative to the control eye using a bioluminescence assay at 7 hours after laser application. The retinal pigmented epithelium (RPE) viability threshold was determined with a fluorescence assay. A computational model was developed to estimate temperature and the extent of cell damage. RESULTS: A significant increase in HSP70 transcription was found at exposures over 20 mW, half the threshold power for RPE cell death. Computational modeling estimated peak temperature T = 49°C at HSP70 expression threshold. At RPE viability threshold, T = 57°C. Similar temperatures and damage indices were calculated for clinical subvisible retinal treatment parameters. CONCLUSIONS: Beneficial effects of laser therapy have been previously shown to extend beyond those resulting from destruction of tissue. One hundred millisecond laser exposures at approximately half the threshold power of RPE damage induced transcription of HSP70, an indication of cellular response to sublethal thermal stress. A computational model of retinal hyperthermia can guide further optimization of laser parameters for nondamaging phototherapy.
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Regulación de la Expresión Génica/fisiología , Proteínas HSP70 de Choque Térmico/genética , Coagulación con Láser/efectos adversos , Láseres de Estado Sólido/efectos adversos , Retina/lesiones , Animales , Supervivencia Celular , Simulación por Computador , Análisis de Elementos Finitos , Perfilación de la Expresión Génica , Genes Reporteros , Mediciones Luminiscentes , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Modelos Animales , Retina/metabolismo , Epitelio Pigmentado de la Retina/metabolismoRESUMEN
PURPOSE: To evaluate a new pulsed-electron avalanche knife design for creating a continuous curvilinear capsulotomy (CCC) and compare the CCC with a mechanical capsulorhexis. SETTING: Department of Ophthalmology, Stanford University, Stanford, California, USA. METHODS: In this study, CCCs were created in freshly enucleated bovine eyes and in rabbit eyes in vivo. The cutting velocity was adjusted by controlling the burst repetition rate, voltage amplitude, and burst duration. Tissue samples were fixed and processed for histology and scanning electron microscopy (SEM) immediately after surgery. RESULTS: The study included 50 bovine eyes and 10 rabbit eyes. By adjusting the electrosurgical waveforms, gas-bubble formation was minimized to permit good surgical visualization. The optimum voltage level was determined to be +/-410 V with a burst duration of 20 mus. Burst repetition rate, continuously adjustable from 20 to 200 Hz with footpedal control, allowed the surgeon to vary linear cutting velocity up to 2.0 mm/s. Histology and SEM showed that the pulsed-electron avalanche knife produced sharp-edged capsule cutting without radial nicks or tears. CONCLUSIONS: The probe of the pulsed-electron avalanche knife duplicated the surgical feel of a 25-gauge cystotome and created a histologically smooth capsule cut. It may improve precision and reproducibility of creating a CCC, as well as improve its proper sizing and centration, especially in the face of surgical risk factors, such as weak zonules or poor visibility. FINANCIAL DISCLOSURES: Drs. Palanker and Vankov hold patents to the pulsed electron avalanche knife technology, which are licensed to PEAK Surgical by Stanford University. Drs. Palanker and Chang are consultants to PEAK Surgical. Dr. Vankov is an employee of PEAK Surgical. Neither of the other authors has a financial or proprietary interest in any material or method mentioned.
Asunto(s)
Capsulorrexis/instrumentación , Electrocirugia/instrumentación , Cápsula del Cristalino/cirugía , Animales , Capsulorrexis/métodos , Bovinos , Diseño de Equipo , Cápsula del Cristalino/ultraestructura , Microscopía Electrónica de Rastreo , Conejos , PorcinosRESUMEN
PURPOSE: To investigate the pharmacokinetics of bevacizumab in rabbits for three different routes of administrations: intravitreal injection, subconjunctival injection, and eye drops. METHODS: Pigmented rabbits received bevacizumab in one eye by topical eye drops (1.25 mg/0.05 mL six times daily for the first 7 days), single subconjunctival injection (1.25 mg/0.05 mL), or single intravitreal injection (1.25 mg/0.05 mL). Bevacizumab concentrations in plasma and ocular tissues in the treated and fellow eyes were determined by sandwich enzyme-linked immunosorbent assay at 1, 2, 4, and 12 weeks after administration. RESULTS: After intravitreal injection in the treated eye, the mean maximum concentrations (C(max)) of bevacizumab in the iris/ciliary body and retina/choroid were 109,192.6, and 93,990.0 ng/g, respectively, whereas after subconjunctival injection, the C(max) was 1418.7 and 295.8 ng/g, respectively. In the fellow eyes, when the drug was administered by intravitreal injection, the C(max) was 753.6 ng/g in the iris/ciliary body and 224.2 ng/g in the retina/choroid and by subconjunctival injection was 1192.9 and 187.0 ng/g, respectively. With eye drops, only a small level of bevacizumab was detected in the iris/ciliary body and retina/choroid. Systemic exposure to bevacizumab was at the same level when administered by intravitreal or subconjunctival injection. CONCLUSIONS: Intravitreal injection of bevacizumab was the most effective route of administration for intraocular tissue. Also, bevacizumab injected subconjunctivally was transported into the intraocular tissues of the treated eyes at an effective level. Both intravitreal and subconjunctival injections of bevacizumab resulted in high plasma concentrations. Bevacizumab was distributed into the intraocular tissues in fellow eyes via the systemic circulation. This treatment may be effective for blocking vascular endothelial growth factor activity.