Visualisation of primary prostate cancer, its relapse and its metastases is a clinically relevant problem despite the availability of state-of-the-art methods such as CT, MRI, transrectal ultrasound and fluorine-18 fluorodeoxyglucose positron emission tomography ((18)F-FDG PET). The aim of this study was to evaluate the efficacy of carbon-11 acetate and (18)F-FDG PET in the detection of prostate cancer and its metastases. Twenty-five patients were investigated during the follow-up of primary prostate cancer, suspected relapse or metastatic disease using (11)C-acetate PET; 15 of these patients were additionally investigated using (18)F-FDG PET. Fourteen patients were receiving anti-androgen treatment at the time of the investigation. Lesions were detected in 20/24 (83%) patients using (11)C-acetate PET and in 10/15 (75%) patients using (18)F-FDG PET. Based on the results of both PET scans, one patient was diagnosed with recurrent lung cancer. Median (18)F-FDG uptake exceeded that of (11)C-acetate in distant metastases (SUV =3.2 vs 2.3). However, in local recurrence and in regional lymph node metastases, (11)C-acetate uptake (median SUVs =2.9 and 3.8, respectively) was higher than that of (18)F-FDG (median SUVs =1.0 and 1.1, respectively). A positive correlation was observed between serum PSA level and both (11)C-acetate uptake and (18)F-FDG uptake. (11)C-acetate seems more useful than (18)F-FDG in the detection of local recurrences and regional lymph node metastases. (18)F-FDG, however, appears to be more accurate in visualising distant metastases. There may be a role for combined (11)C-acetate/(18)F-FDG PET in the follow-up of patients with prostate cancer and persisting or increasing PSA.

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Mature liver flukes, Fasciola hepatica, of different ages were isolated from the bile ducts of experimentally infected rats. Their energy metabolism was studied during aerobic incubation with [6-~4C]glucose. The results showed that the aerobic potentials of the parenchymal liver flukes are not lost immediately after arrival in the bile ducts, but in a later phase. During the development of the newly excysted juvenile into the mature adult the major part of ATP production in aerobic incubations is successively contributed by three different pathways of glucose breakdown. The Krebs cycle, which is by far the main energy-yielding pathway of the juvenile fluke, is gradually replaced by aerobic acetate formation and, finally, by the anaerobic dismutation reactions of the adult liver fluke. This observed decrease in Krebs-cycle activity per mg protein is not the result of a decrease in activity per individual fluke. The Krebs-cycle activity per fluke actually increases enormously during its whole development. This indicates that the aerobic potential of adult F. hepatica is not just a remnant of earlier aerobic stages but that classical, mammalian type mitochondria are produced during the entire development of the fluke. Calculations are presented which demonstrate that the Krebs-cycle activity of the developing F. hepatica is directly proportional to the surface area of the fluke. This supports our view that Krebs-cycle activity is limited by the diffusion of oxygen and can only occur in the outer layer of the liver fluke during its entire development in the final host.

Juvenile Fasciola hepatica at different stages of development were isolated from the liver parenchyma of experimentally infected rats. Their energy metabolism was studied by incubation with D-J6 -14 C]glucose and compared with that of juveniles isolated immediately after in vitro emergence from the metacercarial cysts. These studies confirmed that freshly excysted juveniles have an aerobic energy metabolism, but are already fully equipped for life in the absence of oxygen. A functioning Krebs cycle was a true characteristic of all parenchymal stages of F. hepatica, but its capacity slowly decreased during development. Concomitantly, acetate became the major end product. This formation of acetate was an aerobic process and it was the most important source of energy for the exponentially growing fluke after twelve days of development. It might, therefore, be an important new target for anthelmintics. The decrease in Krebs cycle activity was not caused by a lack of oxygen nor by a decreased capacity of the respiratory chain. The freshly excysted juvenile had endogenous glycogen stores which were degraded during fasting and replenished in the presence of glucose.

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