2 research outputs found
Radiochemical Synthesis and Evaluation of <sup>13</sup>N‑Labeled 5‑Aminolevulinic Acid for PET Imaging of Gliomas
The endogenous amino
acid, 5-aminolevulinic acid (5-ALA), has received
significant attention as an imaging agent, including ongoing clinical
trials for image-guided tumor resection due to its selective uptake
and subsequent accumulation of the fluorescent protoporphyrin IX in
tumor cells. Based on the widely reported selectivity of 5-ALA, a
new positron emission tomography imaging probe was developed by reacting
methyl 5-bromolevulinate with [<sup>13</sup>N] ammonia. The radiotracer,
[<sup>13</sup>N] 5-ALA, was produced in high radiochemical yield (65%)
in 10 min and could be purified using only solid phase cartridges. <i>In vivo</i> testing in rats bearing intracranial 9L glioblastoma
showed peak tumor uptake occurred within 10 min of radiotracer administration.
Immunohistochemical staining and fluorescent imaging was used to confirm
the tumor location and accumulation of the tracer seen from the PET
images. The quick synthesis and rapid tumor specific uptake of [<sup>13</sup>N] 5-ALA makes it a potential novel clinical applicable radiotracer
for detecting and monitoring tumors noninvasively
<i>In Vitro</i> Metabolic Stability and <i>in Vivo</i> Biodistribution of 3‑Methyl-4-furoxancarbaldehyde Using PET Imaging in Rats
Painful diabetic neuropathy (PDN)
is a type of peripheral neuropathic
pain that is currently difficult to treat using clinically available
analgesics. Recent work suggests a progressive depletion of nitric
oxide (NO) in nerve cells may be responsible for the pathobiology
of PDN. The nitric oxide donor, 3-methyl-4-furoxancarbaldehyde (PRG150),
has been shown to produce dose-dependent analgesia in a rat model
of PDN. To gain insight into the mechanism of analgesia, methods to
radiolabel PRG150 were developed to assess the <i>in vivo</i> biodistribution in rats. The furoxan ring was labeled with <sup>13</sup>N to follow any nitric oxide release and the 3-methyl substituent
was labeled with <sup>11</sup>C to track the metabolite using PET
imaging. The <i>in vitro</i> metabolic stability of PRG150
was assessed in rat liver microsomes and compared to <i>in vivo</i> metabolism of the synthesized radiotracers. PET images revealed
a higher uptake of <sup>13</sup>N over <sup>11</sup>C radioactivity
in the spinal cord. The differences in radioactive uptake could indicate
that a NO release in the spinal cord and other components of the somatosensory
nervous system may be responsible for the analgesic effects of PRG150
seen in the rat model of PDN