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J Roemer

Publications and source records attributed to J Roemer.

9 recordsLinked to original sources
PubMed1996

18F-desmethoxyfallypride: a fluorine-18 labeled radiotracer with properties similar to carbon-11 raclopride for PET imaging studies of dopamine D2 receptors.

We have developed (S)-N-[(1-allyl-2-pyrrolidinyl)methyl]-5-(3-18F-fluoropropyl)-2- methoxybenzamide (18F-desmethoxyfallypride) as a fluorine-18 radiotracer with properties analogous to that of 11C-raclopride. In vitro experiments in rat brain homogenates showed an association rate constant of 2.16 x 10(8) M(-1)min(-1) and a dissociation rate constant of 0.073 min(-1). High striatal uptake (up to 0.08% injected dose/cc) of 18F-desmethoxyfallypride in rhesus monkeys was observed in PET experiments. The radiotracer cleared from the striata with a dissociation rate of 1.80 x 10(-2) min(-1). Striatum to cerebellum ratios peaked at 3.0 in 30 min after which they decreased steadily. Intravenously administered haloperidol displaced specifically bound 18F-desmethoxyfallypride with a koff of 0.058 min(-1). Synaptic dopamine released by the treatment of the monkeys with d-amphetamine increased the dissociation rate of 18F-desmethoxyfallypride to 0.83 min(-1) thus reducing specifically bound 18F-desmethoxyfallypride by 56% over a period of 42 mins compared to a reduction of only 20% in controls during this time period. The sensitivity of 18F-desmethoxyfallypride towards competition with dopamine should make this radiotracer useful in PET studies to evaluate in vivo pharmacological effects of various agents that alter levels of endogenous dopamine.

Animals↗
PubMed1989

An overview of the food intake patterns of the Cayo Santiago rhesus monkeys (Macaca mulatta): report of a pilot study.

The food ingestion patterns of the rhesus monkeys (Macaca mulatta) of Group L on Cayo Santiago were quantitatively recorded during two months which coincided with the annual breeding season. Three methods of sampling were used concurrently: interval scan sampling, group location mapping and focal animal observation. These data generated time budgets and specifics about foods selected by six age/sex classes of animals. Overall the animals spent 10.8% of their time engaged in eating. This eating time was distributed as 50.2% on commercial diet/other non-naturally occurring food items and 49.8% on natural vegetation of known or unknown plant part. Distinct diurnal rhythms were observed in overall behaviors and food selection patterns. Soil was part of the daily food intake of all animals. Age/sex class differences in volume of food intake and eating bout interruptions indicated that juveniles may adaptively focus on vegetative food sources during times of social stress. The changing environmental conditions on Cayo Santiago are viewed as presenting the opportunity for future studies of perceptual learning and adaptation by groups and the entire population.

Academies and Institutes↗