Documents Page

As part of a larger experiment investigating serotonergic regulation of female marmoset sexual behavior, this study was designed to (1) advance methods for PET imaging of common marmoset monkey brain, (2) measure normalized FDG uptake as an index of local cerebral metabolic rates for glucose, and (3) study changes induced in this index of cerebral glucose metabolism by chronic treatment of female marmosets with a serotonin 1A receptor (5-HT1A) agonist. We hypothesized that chronic treatment with the 5-HT1A agonist 8-OH-DPAT would alter the glucose metabolism index in dorsal raphe (DR), medial prefrontal cortex (mPFC),
medial preoptic area of hypothalamus (mPOA), ventromedial nucleus of hypothalamus (VMH), and field CA1 of hippocampus.
Eight adult ovariectomized female common marmosets (Callithrix jacchus) were studied with and without estradiol replacement. In a crossover design, each subject was treated daily with 8-OH-DPAT (0.1 mg/kg SC daily) or saline. After 42–49 days of treatment, the glucose metabolism radiotracer FDG was administered to each female immediately prior to 30 min of interaction with her male pairmate, after which the subject was anesthetized and imaged by PET. Whole brain normalized PET images were analyzed with anatomically defined regions of interest (ROI). Whole brain voxelwisemappingwas also used to explore treatment effects and correlations between alterations in the glucose metabolism index and pairmate interactions.
The rank order of normalized FDG uptake was VMH/mPOA>DR>mPFC/CA1 in both conditions. 8-OH-DPAT did not induce alterations in the glucose metabolism index in ROIs. Voxelwise mapping showed a significant reduction in normalized FDG uptake in response to 8-OH-DPAT in a cluster in medial occipital cortex as well as a significant correlation between increased rejection of mount attempts and reduced normalized FDG uptake in an overlapping cluster.
In conclusion, PET imaging has been used to measure FDG uptake relative to whole brain in marmoset monkeys. Voxelwise mapping shows that 8-OH-DPAT reduces this index of glucose metabolism in medial occipital cortex, consistent with alterations in female sexual behavior.

Hong et al.
Purpose High tumor microvessel density correlates with a poor prognosis in multiple solid tumor types. The clinical gold standard for assessing microvessel density is CD105 immunohistochemistry on paraffin-embedded tumor specimens. The goal of this study was to develop an 89Zr-based PET tracer for noninvasive imaging of CD105 expression.
Methods TRC105, a chimeric anti-CD105 monoclonal antibody, was conjugated to p-isothiocyanatobenzyldesferrioxamine (Df-Bz-NCS) and labeled with 89Zr. FACS analysis and microscopy studies were performed to compare the CD105 binding affinity of TRC105 and Df-TRC105. PET imaging, biodistribution, blocking, and ex-vivo histology studies were performed on 4T1 murine breast tumor-bearing mice to evaluate the pharmacokinetics and tumor-targeting of 89Zr-Df-TRC105. Another chimeric antibody, cetuximab, was used as an isotype-matched control. Results FACS analysis of HUVECs revealed no difference in CD105 binding affinity between TRC105 and Df-TRC105, which was further validated by fluorescence microscopy. 89Zr labeling was achieved with high yield and specific activity. Serial PET imaging revealed that the
4T1 tumor uptake of 89Zr-Df-TRC105 was 6.1±1.2, 14.3±1.2, 12.4±1.5, 7.1±0.9, and 5.2±0.3 %ID/g at 5, 24, 48, 72, and 96 h after injection, respectively (n=4), higher than all organs starting from 24 h after injection, which provided excellent tumor contrast. Biodistribution data as measured by gamma counting were consistent with the PET findings. Blocking experiments, control studies with 89Zr-Df-cetuximab, and ex-vivo histology all confirmed the in vivo target specificity of 89Zr-Df-TRC105.
Conclusion We report here the first successful PET imaging of CD105 expression with 89Zr as the radiolabel. Rapid, persistent, CD105-specific uptake of 89Zr-Df-TRC105 in the 4T1 tumor was observed.