A well supported mechanism for succinyl-CoA:3-ketoacid coenzyme A transferase (EC 2.8.3.5) involving an enzymeCoA intermediate requires the participation of an oxygen atom of the enzyme or of the CoA moiety. Measurements of loss of 180 from acetoacetate show that CoA oxygens do not participate. An oxygen-containing group on the enzyme is reversibly labeled from succinateJ*O in the presence of a...

This study compared the fat metabolism between "a single bout of prolonged exercise" and "repeated bouts of exercise" of equivalent exercise intensity and total exercise duration. Seven men performed three trials: 1) a single bout of 60-min exercise (Single); 2) two bouts of 30-min exercise, separated by a 20-min rest between exercise bouts (Repeated); and 3) rest. Each exercise was performed w...

We report an analytical reversed-phase liquid-chromatographic procedure for quantifying nicotine and cotinine in urine, taking into account the presence of interfering caffeine frequently encountered in such specimens. These analytes are extracted from the alkalinized urine with chloroform. After evaporation of the chloroform, the residue is dissolved in methanol and injected into a chromatogra...

The nitrate-reducing bacterial strain BunN is able to grow with acetone and nitrate under anoxic conditions. Dialyzed crude cell-free extracts of acetone-plus-nitrate-grown cells of strain BunN catalyzed the exchange of 14CO2 into acetoacetate in an ADP-dependent reaction. The rates of exchange catalyzed by extracts of acetate-grown or 3-hydroxybutyrate-grown cells were only 13% of that catalyz...

Catheterization of cerebral vessels in three obese patients undergoing 5-6 wk of starvation demonstrated that beta-hydroxybutyrate and acetoacetate replaced glucose as the predominant fuel for brain metabolism. A strikingly low respiratory quotient was also observed, suggesting a carboxylation mechanism as a means of disposing of some of the carbon of the consumed substrates.

In the course of a study of the properties of the homogentisic acid oxidase of rat liver the activity of other animal tissues has been briefly examined. The enzyme has been reported to occur in beef and hog (I), guinea pig (2), and rabbit (3) livers and in a strain of Pseudomonas (4). The experiments reported here show that the enzyme is also present in pigeon liver and in guinea pig, rabbit, p...

There is now no doubt that ketone bodies (acetoacetate and D-3-hydroxybutyrate) are important oxidizable substrates for peripheral tissues, especially the brain. Although oxidation is the major fate of ketone bodies, more recent evidence suggests that ketone bodies can act as lipogenic substrates in certain tissues, notably the developing brain and the lactating mammary gland. Apart from their ...

1. An improved perfusion system for the isolated rat heart is described. It is based on the isolated working heart of Neely, Liebermeister, Battersby & Morgan (1967) (Am. J. Physiol. 212, 804-814) and allows the measurement of metabolic rates and cardiac performance at a near-physiological workload. The main improvements concern better oxygenation of the perfusion medium and greater versatility...

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OBJECTIVES To evaluate performance characteristics of the newly available handheld combined glucose and ketone meter for beta-hydroxybutyrate measurement. DESIGN Laboratory method evaluation. MAIN OUTCOME MEASURES Accuracy of beta-hydroxybutyrate measurement and effect of acetoacetate interference at clinically important beta-hydroxybutyrate levels. RESULTS Deming regression analysis of b...