[Autoradiography of experimental blood brain barrier breakdown areas in the rat using pertechnetate as radiotracer]. / Autorradiografía de las áreas de ruptura de la barrera hematoencefálica en la rata mediante el uso de pertecnetato como radiotrazador.

INTRODUCTION: Absence of lipophility and other physical and chemical characteristics make the pertechnetate (99mTcO4 ) a potential autoradiographic radiotracer for the study of the blood brain and encephalic vasculature barrier integrity. PATHIENS and METHODS: Pertechnetate (99mTcO4Na) was i.v. injected (10 15 mCi) to 20 male Sprague Dawley rats. A hypervolemic hypertension was induced in the experimental group (n= 10) by i.v. Ringer infusion (333 mL/min up to 10 mL). Control group (n= 10) received normal hydration (16,6 mL/min). Rats were killed 60 min after 99mTcO4Na by a barbituric overdose and perfused with Ringer followed by formalin 4%. Coronal encephalic slides of 500 mm were located over odontological radiographic plates, allowed to dry for 12 14 hours and processed conventionally. Autoradiographic images were analysed by digital densitometry. RESULTS: Autoradiographies from control animals did not show activity images. Hypervolemic animals presented activity images located predominantly on putamen, caudate and hippocampus. The optical density of the autoradiographic images was correlated to the radioactivity of used standards (r= 0.98; p< 0.0005). Mean two points resolution obtained was 77.29+/-5.2 mm. CONCLUSION: The results suggest the utility of 99mTcO4Na as autoradiographic radiotracer in the experimental study of the blood brain barrier and encephalic vasculature integrity, showing a better two points resolution than that reported for [14C]2 deoxiglucose used for brain regional metabolism studies.

Autorradiografía de áreas de ruptura de la barrera hematoencefálica en la rata mediante el uso de pertecnetato como radiotrazador / Autoradiography of experimental blood-brain barrier breakdown areas in the rat using pertechnetate as radiotracer

Introducción. Las características fisicoquímicas del pertecnetato (99mTcO4-) especialmente su no lipofilidad, lo convierten en un potencial radiotrazador en autorradiografías para el estudio de la integridad tanto de la barrera hematoencefálica como de la vasculatura encefálica. Material y métodos. Se administró 10-15 mCi de 99mTcO4Na iv a 20 ratas Sprague-Dawley machos; seguidamente, al grupo experimental (n= 10) se le indujo hipervolemia administrándole Ringer iv (333 ml/mn) hasta un total de 10 ml, mientras que al grupo control (n= 10) se le administró la hidratación normal (16,6 ml/mn). Transcurridos 60 mn de la administración del 99mTcO4-, los animales sacrificados con una sobredosis barbitúrica, fueron perfundidos con Ringer seguido de formalina al 4 por ciento. Se colocaron cortes coronales encefálicos de 500 mm de espesor sobre placas radiográficas odontológicas, dejadas secar 12-14 horas y reveladas convencionalmente. Las autorradiografías obtenidas se evaluaron con densitometría digital. Resultados. Las autorradiografías de los animales controles no mostraron imágenes de actividad; sin embargo, las de los hipervolémicos mostraron imágenes de actividad localizadas predominantemente en: putamen, caudado e hipocampo. La densidad óptica de las imágenes autorradiográficas se correlacionó con la radiactividad de los patrones (r= 0,98; p< 0,0005). La resolución espacial promedio fue de 77,29 ñ 5,2 mm. Conclusión. Los resultados señalan la utilidad del 99mTcO4Na como radiotrazador autorradiográfico en el estudio experimental de la integridad tanto de la barrera hematoencefálica como de la vasculatura encefálica, mostrando una resolución espacial mejor que la comunicada para la [14C]2-deoxiglucosa, utilizada en el estudio del metabolismo sanguíneo regional cerebral (AU)

Kinetics and distribution of 111Indium-labeled platelets in patients with homocystinuria.

Homocystinuria is an inborn error of metabolism involving a high incidence of thromboembolism. It sometimes improves with large doses of pyridoxine. We investigated the kinetics and distribution of 111Indoxine-labeled platelets in 11 normal volunteers and 12 patients with homocystinuria, none of whom had clinical evidence of acute thrombosis at the time of the study. Six of the patients were resistant to pyridoxine and had homocystinemia. There were no statistical differences in mean platelet-survival times between pyridoxine responders and nonresponders or between normal subjects and pyridoxine responders or nonresponders, regardless of whether a linear, exponential, or multiple-hit model was used to analyze the kinetic data. Plasma homocystine levels had no apparent effect on mean platelet-survival time. There was no abnormal accumulation of platelets in any of the patients, and the distribution of platelets in liver and spleen was similar to that in normal subjects. Our results suggest that the kinetics and distribution of platelets in patients with homocystinuria who have no clinical evidence of thromboembolism are normal. Thus, the data do not provide evidence for disordered platelet function or for an ongoing interaction of platelets with vessel walls in this condition.