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Thiamine is an essential component of glucose metabolism and energy production. The disulfide derivative, thiamine tetrahydrofurfuryl disulfide (TTFD), is better absorbed than readily-available water-soluble thiamine salts because it does not require the rate-limiting transport system required for thiamine absorption. However, the detailed pharmacokinetics of thiamine and TTFD under normal and pathological conditions have not yet been clarified. C-11-labeled thiamine and TTFD were recently synthesized by our group. In this study, to clarify the differences in pharmacokinetics and metabolism of these probes, a quantitative PET imaging study and radiometabolite analysis of C-11-labeled thiamine and TTFD were performed in the rat heart. Positron emission tomography (PET) imaging with [11C]thiamine and [11C]TTFD was performed in normal rats to determine the pharmacokinetics of these probes, and the radiometabolites of both probes from the blood and heart tissue were analyzed by thin-layer chromatography. Accumulation of [11C]TTFD was significantly higher than that of [11C]thiamine in the rat heart. Moreover, as a result of the radiometabolite analysis of heart tissue at 15 min after the injection of [11C]TTFD, thiamine pyrophosphate, which serves as a cofactor for the enzymes involved in glucose metabolism, was found as the major radiometabolite and at a significantly higher level than in the [11C]thiamine-injected group. PET imaging techniques for visualizing the kinetics and metabolism of thiamine using [11C]thiamine and [11C]TTFD were developed in this study. Consequently, noninvasive PET imaging for the pathophysiology of thiamine-related cardiac function may provide novel information about heart failure and related disorders.

In vivo detection of pathological insults during the early stages of rheumatoid synovitis is essential to allow early anti-inflammatory treatment for prevention of joint destruction. Whether rheumatoid synovitis pathology and the efficacy of therapies can be visualized by positron emission tomography (PET) tracers specific to the inflammatory process was investigated. Using a collagen-induced experimental rat model of rheumatoid arthritis, in vivo imaging using the PET tracers [11C]PK11195, which binds to the translocator protein mainly expressed on myeloid cells, and [11C]ketoprofen, for cyclooxygenase imaging, was performed. To evaluate therapeutic efficacy, model animals were administered the tumour necrosis factor alpha blocker etanercept subcutaneously. [11C]PK11195 and [11C]ketoprofen uptakes were significantly higher in inflamed paws of collagen-induced arthritis rats than in normal rats. The data showed a correlation between tracer uptake values and paw swelling. After treatment with etanercept, [11C]ketoprofen uptake was significantly lower in treated animals than in untreated ones, whereas [11C]PK11195 uptake in the inflamed regions was comparable to that in the untreated group. With [11C]PK11195 and [11C]ketoprofen tracers, non-invasive in vivo PET imaging for rheumatoid synovitis can provide diagnostic evidence of early synovitis and allow monitoring inflammatory cell activity during treatment.

Thiamine is an essential component of glucose metabolism and energy production. The disulfide derivative, thiamine tetrahydrofurfuryl disulfide (TTFD), is better absorbed than readily-available water-soluble thiamine salts because it does not require the rate-limiting transport system required for thiamine absorption. However, the detailed pharmacokinetics of thiamine and TTFD under normal and pathological conditions have not yet been clarified. C-11-labeled thiamine and TTFD were recently synthesized by our group. In this study, to clarify the differences in pharmacokinetics and metabolism of these probes, a quantitative PET imaging study and radiometabolite analysis of C-11-labeled thiamine and TTFD were performed in the rat heart.Positron emission tomography (PET) imaging with [Accumulation of [PET imaging techniques for visualizing the kinetics and metabolism of thiamine using [

In vivo detection of pathological insults during the early stages of rheumatoid synovitis is essential to allow early anti-inflammatory treatment for prevention of joint destruction. Whether rheumatoid synovitis pathology and the efficacy of therapies can be visualized by positron emission tomography (PET) tracers specific to the inflammatory process was investigated.Using a collagen-induced experimental rat model of rheumatoid arthritis, in vivo imaging using the PET tracers [[With [