Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds

The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects

Drilling constraints on lithospheric accretion and evolution at Atlantis Massif, Mid-Atlantic Ridge 30°N

Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): B07103, doi:10.1029/2010JB007931.Expeditions 304 and 305 of the Integrated Ocean Drilling Program cored and logged a 1.4 km section of the domal core of Atlantis Massif. Postdrilling research results summarized here constrain the structure and lithology of the Central Dome of this oceanic core complex. The dominantly gabbroic sequence recovered contrasts with predrilling predictions; application of the ground truth in subsequent geophysical processing has produced self-consistent models for the Central Dome. The presence of many thin interfingered petrologic units indicates that the intrusions forming the domal core were emplaced over a minimum of 100–220 kyr, and not as a single magma pulse. Isotopic and mineralogical alteration is intense in the upper 100 m but decreases in intensity with depth. Below 800 m, alteration is restricted to narrow zones surrounding faults, veins, igneous contacts, and to an interval of locally intense serpentinization in olivine-rich troctolite. Hydration of the lithosphere occurred over the complete range of temperature conditions from granulite to zeolite facies, but was predominantly in the amphibolite and greenschist range. Deformation of the sequence was remarkably localized, despite paleomagnetic indications that the dome has undergone at least 45° rotation, presumably during unroofing via detachment faulting. Both the deformation pattern and the lithology contrast with what is known from seafloor studies on the adjacent Southern Ridge of the massif. There, the detachment capping the domal core deformed a 100 m thick zone and serpentinized peridotite comprises ∼70% of recovered samples. We develop a working model of the evolution of Atlantis Massif over the past 2 Myr, outlining several stages that could explain the observed similarities and differences between the Central Dome and the Southern Ridge

Convergent synthesis of 13N-labelled Peptidic structures using aqueous [13N]NH3

Abstract Background Nitrogen-13 has a 10-min half-life which places time constraints on the complexity of viable synthetic methods for its incorporation into PET imaging agents. In exploring ways to overcome this limitation, we have used the Ugi reaction to develop a rapid one-pot method for radiolabelling peptidic molecules using [13N]NH3 as a synthetic precursor. Methods Carrier-added [13N]NH3 (50 μL) was added to a solution of carboxylic acid, aldehyde, and isocyanide in 2,2,2-TFE (200 μL). The mixture was heated in a microwave synthesiser at 120 °C for 10 min. Reactions were analysed by radio-HPLC and radio-LCMS. Isolation of the target 13N–labelled peptidic Ugi compound was achieved via semi-preparative radio-HPLC as demonstrated for Ugi1. Results Radio-HPLC analysis of each reaction confirmed the formation of radioactive products co-eluting with their respective reference standards with radiochemical yields of the crude products ranging from 11% to 23%. Two cyclic γ-lactam structures were also achieved via intra-molecular reactions. Additional radioactive by-products observed in the radio-chromatogram were identified as 13N–labelled di-imines formed from the reaction of [13N]NH3 with two isocyanide molecules. The desired 13N–labelled Ugi product was isolated using semi-preparative HPLC. Conclusion We have developed a one-pot method that opens up new routes to radiolabel complex, peptidic molecules with 13N using aqueous [13N]NH3 as a synthetic precursor

Do we say what we mean and mean what we say?

Over the last 7 decades the use of radionuclides in the natural andlife sciences has been crucial in enabling groundbreaking discoveriesin basic research and its application to the understanding, diagnosingand treatment of human disease. Numerous innovations in nuclearchemistry/physics, radiochemistry and instrumentation (from nuclearreactors and cyclotrons to new imaging devices) have enabled the ap-plication of radiolabeled molecules in biochemistry, physiology, phar-macology, clinical diagnosis and therapy. These developments haverelied on the continual evolution of cross-disciplinary interactions be-tween researchfields, resulting in a new generation of researchersfrom disparate scientific backgrounds working very successfullytogether.The importance of a unified language betweenfields has long beenrecognized and resulted in the establishment of SI units and IUPAC no-menclature to enableunambiguous scientific communication. However,despite this, the meaning of scientific terms has sometimes beeninterpreted in slightly different ways within different disciplines. Overrecent years in thefield of radiopharmaceutical sciences we havewitnessed an increased incidence of ambiguous scientificlanguage.Many examples of the incorrect usage of established terms and conven-tions and the appearance of new‘self-invented’terms can now be foundin theliterature and at scientific meetings.Thedeparture from the useofa common language is contributing to misunderstanding and confusionwithin our scientific community, and in our communication with otherscientificdiscipline