PET-Based Human Dosimetry of the Dimeric αvß3 Integrin Ligand 68Ga-DOTA-E-[c(RGDfK)]2, a Potential Tracer for Imaging Tumor Angiogenesis.

UNLABELLED: Peptides containing the Arg-Gly-Asp (RGD) sequence have high affinity for αvß3 integrin receptors overexpressed in tumor cells. The objective of this research was to determine the biodistribution and estimate the radiation dose from (68)Ga-DOTA-E-[c(RGDfK)]2 using whole-body PET scans in humans. METHODS: Five healthy volunteers (2 women, 3 men; mean age ± SD, 37.2 ± 15.6 y; range, 28-65 y; mean weight, 79.2 ± 21.0 kg; range, 64-115 kg) were included. After intravenous injection of the tracer (198.3 ± 3.3 MBq), 3 successive whole-body (vertex to mid thigh) PET/CT scans at 3 time points (30, 60, and 120 min) were obtained on a 16-slice PET/CT scanner. The subjects did not void the bladder until the entire series of images was completed. Low-dose CT without contrast agent was used for anatomic localization and attenuation correction. OLINDA/EXM software was applied to calculate human radiation doses using the reference adult model. RESULTS: The highest uptake was in the urinary bladder, followed by the liver, kidneys, and spleen, in descending order. The critical organ was the urinary bladder wall. The mean effective doses (all subjects, men and women) were 34.1 ± 4.9, 31.0 ± 2.4, and 20.9 ± 5.2 µSv/MBq for the no-voiding, 2.5-h-voiding, and 1-h-voiding models, respectively. CONCLUSION: Of particular interest in this research was the visualization of the choroid plexus and ventricular system, which seems to be a characteristic of RGD-dimeric peptides. Measured absorbed doses and effective doses are comparable to other previously reported RGD-based radiopharmaceuticals labeled with (68)Ga and (18)F. Therefore, (68)Ga-DOTA-E-[c(RGDfK)]2 can safely be used for imaging integrin αVß3 expression.

Asfixia e hiperamonemia en el recién nacido / Asphyxia and hiperammanemia in the newborn infant

Con el propósito de evaluar la incidencia de hiperamonemia en el recién nacido asfixiado, se estudiaron 93 neonatos, que fueron divididos en cuatro grupos: A) 25 niños a término normales; B) 25 niños a término asfixiados; C) 23 niños pretérmino normales y D) 20 niños pretérmino asfixiados. Los niños de los grupos A y C tuvieron niveles de amonio en sangre normal; los niños asfixiados (grupos B y D) cursaron con hiperamonemia. Al comparar los grupos A y B y los grupos C y D se encontró una diferencia significativa respecto al indice de Apgar y el nivel de amonio en sangre. La incidencia de hiperamonemia fue de 95% para los niños asfixiados. Se concluye que la determinación de amonio en sangre es necesaria en todo niño que presenta asfixia al nacer