We determine the decay rate constants of zero-, double- and single-quantum coherence for 13C spin pairs in magic-angle-spinning solid-state NMR. The double-quantum coherence is excited by a C7 pulse sequence and converted into zero-quantum coherence by a frequency-selective pair of pi/2 pulses. The zero-quantum coherence is reconverted into observable magnetization by a second pair of pi/2 puls...

AIM To examine the gastrointestinal handling and metabolic disposal of emulsified [1-13C]palmitic acid esterified into a triglyceride in nine healthy children and seven patients with cystic fibrosis on enzyme replacement treatment. METHODS After an overnight fast, each child was given 10 mg/kg body weight [1,1,1-13C]tripalmitin with a standardised test meal of low natural 13C abundance. The t...

The time courses of incorporation of 13C from 13C-labelled glucose or acetate into cerebral amino acids (glutamate, glutamine and 4-aminobutyrate) and lactate were monitored by using 13C-n.m.r. spectroscopy. When [1-13C]glucose was used as precursor the C-2 of 4-aminobutyrate was more highly labelled than the analogous C-4 of glutamate, whereas no label was observed in glutamine. A similar patt...

Ingestion of pure fructose stimulates de novo lipogenesis and gluconeogenesis. This may however not be relevant to typical nutritional situations, where fructose is invariably ingested with glucose. We therefore assessed the metabolic fate of fructose incorporated in a mixed meal without or with glucose in eight healthy volunteers. Each participant was studied over six hours after the ingestion...

The generation of 13C-labelled lactate by colon carcinoma cells of the Caco-2 line incubated for 120 min in the presence of [2-13C]propionate (10 mM) was assessed by 13C NMR. About 10% of the total amount of 13C-labelled lactate was recovered in the cell pellet and displayed a [2-13C]lactate/[3-13C]lactate isotopomer ratio of 1.18 +/- 0.01. An even higher isotopomer ratio of 1.53 +/- 0.14 was o...

Incorporation of 13C label from either [1-13C]glucose to glutamate C-4 and lactate C-3 or from [2-13C]acetate to glutamate C-4 was monitored in situ in a superfused brain slice preparation by using 1H-detected/13C-edited (1H/13C) n.m.r. spectroscopy. The fractional enrichments of both metabolites were determined by this means in both brain slices and acid extracts of the preparations in order t...

Sodium nitroprusside is a valuable vasodilator, but its use has been curtailed because of numerous reports that, in the presence of blood, nitroprusside decomposes with release of toxic cyanide. We have examined the release of cyanide in terms of the known chemistry of nitroprusside and suggest that photochemical decomposition of nitroprusside and (or) its metabolism in vivo invalidates the ana...