RESUMEN
Chloroquine is quinolone derivative known to exert dose-related retinal toxicity, albeit in a variable manner. It is thought that variability in the presentation of chloroquine retinopathy may be the result of perturbations in drug bioavailability subsequent to oral ingestion. In order to better understand the ramifications of bioavailability on the development of retinal injury subsequent to chloroquine use, this study investigated the relationship between retinal injury and chloroquine administration via intraperitoneal rather than oral administration. Four-week-old C57/6J mice underwent daily intraperitoneal injection of 10 mg kg(-1) chloroquine hydrochloride for a total of 62 days. Following treatment, tissue was fixed in preparation for analysis by light and transmission electron microscopy. Treated animals demonstrated marked abnormality of the outer retinal layers described as complete loss of the outer plexiform layer as well as photoreceptors and photoreceptor nuclei. The retinal pigmented epithelium demonstrated focal atrophy, loss of nuclei and pigment irregularity. Findings in the inner retina were notable for the loss of Müller cells and the presence of membranous cytoplasmic bodies. Retinae of control animals were entirely normal. In contrast to previous studies in the murine model examining chloroquine retinopathy subsequent to oral administration, this study suggests that intraperitoneal chloroquine administration facilitates retinal toxicity, presumably due to heightened drug absorption and bioavailability. It is posited that an increased rate of drug accumulation within the retina leads to an enhanced lysosomotrophic drug effect due to inability of the lysosome to compensate for chloroquine-induced elevation in pH through re-acidification of the intra-lysosomal content.
Asunto(s)
Antimaláricos/toxicidad , Cloroquina/toxicidad , Retina/efectos de los fármacos , Enfermedades de la Retina/inducido químicamente , Animales , Coroides/efectos de los fármacos , Coroides/patología , Modelos Animales de Enfermedad , Inyecciones Intraperitoneales , Ratones , Nervio Óptico/efectos de los fármacos , Nervio Óptico/patología , Epitelio Pigmentado Ocular/efectos de los fármacos , Epitelio Pigmentado Ocular/ultraestructura , Retina/patología , Retina/ultraestructura , Enfermedades de la Retina/patologíaRESUMEN
PURPOSE: Respiratory motion can be a complicating factor during image-guided interventions. The ability to reproduce breath-holds may facilitate safer needle-based procedures. The purpose of this study was to evaluate if respiratory biofeedback decreased variability among breath-holds and if the signals from the respiratory bellows belt can be used to measure target motion. MATERIALS AND METHODS: In phase 1 of the study, a respiratory bellows belt was applied to patients before image-guided interventional procedures. Belt stretch from respiratory motion was converted into voltage readings and displayed on a monitor as biofeedback. Patients were asked to perform inspiratory, expiratory, and midcycle breath-holds with and without the biofeedback. The variability in voltage readings between breath-holds with and without biofeedback was compared. In phase 2, the respiratory bellows belt was used during computed tomography (CT)-guided procedures with the patients blinded to the biofeedback. Voltage readings and CT series numbers were recorded as patients were asked to hold their breath during scans. The variability of CT z-axis targets was compared with the variability of voltage readings. RESULTS: A significant decrease in variability was found during expiratory breath-holds (P = .0083) with trends toward significance with midcycle and inspiratory breath-holds. A positive correlation (Kendall tau = 0.5; P = .024) was shown between CT z-axis and belt stretch variability in subjects who received smaller doses of moderate sedation compared with those who received larger doses or general anesthesia. CONCLUSIONS: Biofeedback may help the patient to have a more consistent breath-hold. The belt could decrease the error and unpredictability from craniocaudal motion of targets during image-guided interventions.
Asunto(s)
Artefactos , Neoplasias/diagnóstico por imagen , Radiografía Intervencional/instrumentación , Mecánica Respiratoria , Procesamiento de Señales Asistido por Computador/instrumentación , Tomografía Computarizada por Rayos X , Adulto , Anciano , Estudios Cruzados , Diseño de Equipo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias/fisiopatología , Radiografía Intervencional/métodos , Reproducibilidad de los ResultadosRESUMEN
A 45-year-old male with renal cell carcinoma secondary to von-Hippel Lindau (VHL) disease presented for radiofrequency ablation (RFA) of kidney tumors. Due to his prior history of several partial nephrectomies and limited renal reserve, RFA was chosen because of its relatively nephron-sparing nature. A laser guidance device was used to help guide probe placement in an attempt to reduce procedure time and improve targeting accuracy. The device was successful at guiding needle placement, as both tumors were located with a single pass. Follow-up CT scan confirmed accurate needle placement, showing an area of coagulation necrosis covering the previously seen tumor.