(123)I-labeled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)nortropane ((123)I-FP-CIT) was approved for clinical use in 2011 by the Food and Drug Administration. (123)I-FP-CIT is a radioligand for brain dopamine transporter (DAT) imaging that is useful for the differential diagnosis of Parkinson disease (PD) and other diseases that mimic PD. The sensitivity and specificity of (123)I-FP-C...

In 1939 Schoenheimer, Ratner, and Rittenberg (1) employed nn-tyrosine labeled with heavy nitrogen (N15) to study the metabolism of this amino acid and the fate of its amino nitrogen in rats. The present investigation deals with the metabolism in rats of radioactive nn-tyrosine (tyrosine”), labeled in the /3 position with the long lived Cl* isotope of carbon (2).l The labeling of the carbon skel...

Geboes, Karen P., Vicky De Preter, Anja Luypaerts, Bert Bammens, Pieter Evenepoel, Yvo Ghoos, Paul Rutgeerts, and Kristin Verbeke. Validation of lactose[N,N]ureide as a tool to study colonic nitrogen metabolism. Am J Physiol Gastrointest Liver Physiol 288: G994–G999, 2005. First published December 30, 2004; doi:10.1152/ajpgi.00408.2004.—In vitro experiments have shown that fermentation of carbo...

Regulation of organic N metabolism by inorganic N availability was investigated in short-term laboratory incubations of soil. A C-, N-labeled organic N substrate was produced by growing Pseudomonas stutzeri in labeled media and isolating a cytoplasmic fraction. This was added to soils that had been preincubated with glucose or glucose plus NHJ to induce conditions of N deficiency or sufficiency...

Dietary nitrogen was traced in rats adapted to a 50% protein diet and given a meal containing 1.50 g (15)N-labeled protein (HP-50 group). This group was compared with rats usually consuming a 14% protein diet and fed a meal containing either 0.42 g (AP-14 group) or 1.50 g (AP-50 group) of (15)N-labeled protein. In the HP group, the muscle nonprotein nitrogen pool was doubled when compared with ...

An earlier report (1) dealing with the distribution of isotopic nitrogen in cells of Axotobacter vinelandii fixing molecular nitrogen provided evidence that ammonia might be the initial stable form of nitrogen in the fixation process. This conclusion was based on the observation that the N’s supplied this organism accumulated in the glutamic acid fraction, as had been already observed in higher...

This experiment was done to investigate microbial contamination and in situ disappearance rates of dry matter (DM), N and 15N of fresh labeled ryegrass. Perennial ryegrass (Lolium perenne) were labeled with 15N during growth in a glasshouse, harvested at 4th leaves stage and were incubated up to 34 h in situ in the rumen of 3 individually housed sheep. The animals were fed 800 g/d chopped alfal...

Abstract Solid-state NMR spectroscopy represents a powerful method for the investigation of diatom biosilica but detailed studies regarding its chemical composition and structural organization can be prohibited by insufficient spectroscopic sensitivity. Here, we used two-dimensional (2D) Dynamic Nuclear Polarization (DNP)-supported solid-state experiments to obtain information about molecular s...