Significance: Cancers require high amounts of glucose to grow and survive, and dogma is that uptake is facilitated by passive glucose transporters (GLUTs). We have identified a new mechanism to import glucose into pancreatic and prostate cancer cells, namely active glucose transport mediated by sodium-dependent glucose transporters (SGLTs). This means that the specific radioactive imaging probe for SGLTs, α-methyl-4-deoxy-4-[ ¹⁸ F]fluoro- d -glucopyranoside, may be used along with positron-emission tomography to diagnose and stage pancreatic and prostate cancers, tumors in which the GLUT probe 2-[ ¹⁸ F]fluoro-2-deoxy- d -glucose has questionable utility. Moreover, we suggest, based on our results in mouse models, that Food and Drug Administration-approved SGLT2 inhibitors may be used to reduce the viability of pancreatic and prostate cancer cells in patients.

4-[F-18]fluoro- N -{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}- N -(2-pyridinyl)benzamide, a selective serotonin 1A (5-HT _1A ) molecular imaging probe, was used in conjunction with positron emission tomography (PET) for quantification of 5-HT _1A receptor densities in the living brains of Alzheimer's disease patients (ADs) ( n = 8), subjects with mild cognitive impairment ( n = 6), and controls ( n = 5). ADs had receptor densities significantly decreased in both hippocampi (binding potential: controls 1.62 ± 0.07; ADs 1.18 ± 0.26) and also in raphe nuclei (controls 0.63 ± 0.09; ADs 0.37 ± 0.20). When volume losses are included, 5-HT _1A losses are even more severe (i.e., average mean decreases of 24% in mild cognitive impairment patients and 49% in ADs). A strong correlation of 5-HT _1A receptor decreases in hippocampus with worsening of clinical symptoms (Mini Mental State Exam scores) was also found. Moreover, these decreases in 5-HT _1A receptor measures correlate with decreased glucose utilization as measured with 2-deoxy-2-[F-18]fluoro- d -glucose PET in the brains of ADs (standardized uptake values; globally: controls 0.89 ± 0.04, ADs 0.72 ± 0.04; posterior cingulate gyrus: controls 1.05 ± 0.09, ADs 0.79 ± 0.11). They also inversely correlate with increased neuropathological loads measured with 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile PET in several neocortical regions in the same subjects. The in vivo observations were confirmed independently by in vitro digital autoradiography with 4-[F-18]fluoro- N -{2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl}- N -(2-pyridinyl)benzamide and 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}-ethylidene)malononitrile on brain tissue specimens from two ADs and three nondemented subjects.

Chronic traumatic encephalopathy (CTE) is an acquired primary tauopathy with a variety of cognitive, behavioral, and motor symptoms linked to cumulative brain damage sustained from single, episodic, or repetitive traumatic brain injury (TBI). No definitive clinical diagnosis for this condition exists. In this work, we used [F-18]FDDNP PET to detect brain patterns of neuropathology distribution in retired professional American football players with suspected CTE (n = 14) and compared results with those of cognitively intact controls (n = 28) and patients with Alzheimer’s dementia (AD) (n = 24), a disease that has been cognitively associated with CTE. [F-18]FDDNP PET imaging results in the retired players suggested the presence of neuropathological patterns consistent with models of concussion wherein brainstem white matter tracts undergo early axonal damage and cumulative axonal injuries along subcortical, limbic, and cortical brain circuitries supporting mood, emotions, and behavior. This deposition pattern is distinctively different from the progressive pattern of neuropathology [paired helical filament (PHF)-tau and amyloid-β] in AD, which typically begins in the medial temporal lobe progressing along the cortical default mode network, with no or minimal involvement of subcortical structures. This particular [F-18]FDDNP PET imaging pattern in cases of suspected CTE also is primarily consistent with PHF-tau distribution observed at autopsy in subjects with a history of mild TBI and autopsy-confirmed diagnosis of CTE.

Na⁺-glucose cotransporter (SGLT) mRNAs have been detected in many organs of the body, but, apart from kidney and intestine, transporter expression, localization, and functional activity, as well as physiological significance, remain elusive. Using a SGLT-specific molecular imaging probe, α-methyl-4-deoxy-4-[¹⁸F]fluoro-d-glucopyranoside (Me-4-FDG) with ex vivo autoradiography and immunohistochemistry, we mapped in vivo the regional distribution of functional SGLTs in rat brain. Since Me-4-FDG is not a substrate for GLUT1 at the blood-brain barrier (BBB), in vivo delivery of the probe into the brain was achieved after opening of the BBB by an established procedure, osmotic shock. Ex vivo autoradiography showed that Me-4-FDG accumulated in regions of the cerebellum, hippocampus, frontal cortex, caudate nucleus, putamen, amygdala, parietal cortex, and paraventricular nucleus of the hypothalamus. Little or no Me-4-FDG accumulated in the brain stem. The regional accumulation of Me-4-FDG overlapped the distribution of SGLT1 protein detected by immunohistochemistry. In summary, after the BBB is opened, the specific substrate for SGLTs, Me-4-FDG, enters the brain and accumulates in selected regions shown to express SGLT1 protein. This localization and the sensitivity of these neurons to anoxia prompt the speculation that SGLTs may play an essential role in glucose utilization under stress such as ischemia. The expression of SGLTs in the brain raises questions about the potential effects of SGLT inhibitors under development for the treatment of diabetes.

Objective: Currently [18 F]FDDNP is the only PET imaging probe with the ability to visualize hyperphosphorylated tau fibrillar aggregates in living subjects. In this work, we evaluate in vivo [18 F]FDDNP labeling of brain neuropathology, primarily ta