Quinolinic acid (pyridine-cr , /3-dicarboxylic acid) has been isolated from rat urine after administration of tryptophan to rats (1). It has been suggested that quinolinic acid is formed via 3-hydroxyanthranilic acid by oxidative cleavage of the benzene ring in the 3-4 position, followed by closure incorporating the amino nitrogen in a pyridine ring (1). In this paper are reported the results o...

Nanodiamonds (NDs) containing silicon vacancy (SiV) defects were evaluated as a potential biomarker for the labeling and fluorescent imaging of neural precursor cells (NPCs). SiV-containing NDs were synthesized using chemical vapor deposition and silicon ion implantation. Spectrally, SiV-containing NDs exhibited extremely stable fluorescence and narrow bandwidth emission with an excellent signa...

When it was discovered in this laboratory that sarcosine and dimethylglycine are oxidized to formaldehyde by riboflavin phosphate and riboflavin in the absence of protein,1 this observation was pursued, not only because of our interest in the enzymatic oxidation of these substrates, but also because of its implications regarding the origin of biochemical reactions. Subsequent studies to be desc...

A nitrosamine photooxidation reaction is shown to generate a peroxy intermediate by experimental physical-organic methods. The irradiation of phenyl and methyl-substituted nitrosamines in the presence of isotopically labeled 18-oxygen revealed that an O atom was trapped from a peroxy intermediate to trimethylphosphite or triphenylphosphine, or by nitrosamine itself, forming two moles of nitrami...

References .......................................................................... 27 Abstract The vast majority of PET radiopharmaceuticals today are cyclotron produced. Carbon-11 (C), Nitrogen-13 (N), Oxygen-15 (O) products are created for in-house use only due to their short half-lives. The longer half-life of Fluorine-18 means that F-labeled PET radiotracers can be widely distributed. Pr...

I N 1959, ATHENS AND MAUER and their respective collaborators’2 described methods for labeling polymorphonuclear leukocytes with P 52 tagged diisopropylfluorophosphate ( DFP32 ) and subsequently isolating those cells from whole blood. Using that method, they have contributed most of what is known about the intravascular survival and distribution of neutrophils in normal persons. However, that m...

The vasculature of the dorsal suture of cowpea (Vigna unguiculata [L.] Walp) fruits bled a sugar-rich exudate when punctured with a fine needle previously cooled in liquid N(2). Bleeding continued for many days at rates equivalent to 10% of the estimated current sugar intake of the fruit. A phloem origin for the exudate was suggested from its high levels (0.4-0.8 millimoles per milliliter) of s...

Recent studies have documented transfer of labeled nitrogen from [2-(15)N]glutamine to citrulline and arginine in fasting human adults. Conversely, in neonates and piglets we have shown no synthesis of arginine from [2-(15)N]glutamate, and others have shown in mice that glutamine is a nitrogen, but not a carbon donor, for arginine synthesis. Therefore, we performed a multitracer study to determ...

Lambir Hills National Park in Malaysian Borneo is composed of dipterocarp tree species which specialize on different soil types. Although the mechanisms contributing to this distribution of tree species are unknown, one hypothesis is that tree species at Lambir differ in their preferences for different nitrogen forms. In this study we investigated (1) whether clay soil and sandy loam soil types...