Summary:Positron emission tomography studies with the opiate antagonist [18F]cyclofoxy ([18F]CF) were per formed in baboons. Bolus injection studies demonstrated initial uptake dependent on blood flow. The late uptake showed highest binding in caudate nuclei, amygdala, thal amus, and brainstem and the least accumulation in cere bellum. By 60 min postinjection, regional brain radioac tivity cleared at the same rate as metabolite-corrected plasma, i.e., transient equilibrium was achieved. Com partmental modeling methods were applied to time activity curves from brain and metabolite-corrected plasma. Individual rate constants were estimated with poor precision. The model estimate of the total volume of distribution (VT), representing the ratio of tissue radioac tivity to metabolite-corrected plasma at equilibrium, was reliably determined. The apparent volume of distribution Va significantly overestimated V T and produced artifi cially high image contrast. These differences were pre dicted by compartment model theory and were caused by a plasma clearance rate that was close to the slowest tissue clearance rate. To develop a simple method to mea sure V T' an infusion protocol consisting of bolus plus continuous infusion (B/I) of CF was designed and applied in a separate set of studies. The Va values from the B/I studies agreed with the V T values from both B/I and bolus studies. This infusion approach can produce accurate re ceptor measurements and has the potential to shorten scan time and simplify the acquisition and processing of scan and blood data.

Nine adults who had been reared by mothers diagnosed with psychosis reported on their childhood experiences. Analysis of the retrospective data revealed the five common themes of abuse and neglect, isolation, guilt and loyalty, grievances about mental health services, and social supports. The resilience and coping strategies of the participants are examined, and implications for therapeutic interventions with such families are discussed.

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6-[18F]Fluorodopamine produces negligible hemodynamic effects and acceptable radiation exposure at doses that visualize the left ventricular myocardium. Sympathetic nerves take up 6-[18F]fluorodopamine, which is translocated from the axoplasm into storage vesicles, where is it beta-hydroxylated to the fluorinated analogue of the sympathetic neurotransmitter norepinephrine. Therefore, the basis for visualization of myocardium after 6-[18F]fluorodopamine injection in humans is radiolabeling by 6-[18F]fluorodopamine and 6-[18F]fluoronorepinephrine of vesicles in sympathetic terminals. 6-[18F]Fluorodopamine PET scanning provides a novel means for assessing sympathetic innervation and function noninvasively in the human heart.

In the present study we synthesize 18F-labeled insulin of high specific radioactivity. A new prosthetic group methodology, in which [18F]fluoride displaces a bromide group of 4-(bromomethyl)-benzoylamine intermediates, was used. The 4-(fluoromethyl)benzoyl product was chemically stable. 18F-Labeled insulin retains the essential biological properties of native insulin, as measured in vitro by binding to insulin receptors on human cells and stimulation of glucose metabolism in rat adipocytes. The overall process can be carried out speedily to yield a product of sufficient purity to permit in vivo studies. The method appears to be applicable to a wide variety of peptides.