This is an automated method for the kinetic measurement of the combined concentrations of acetoacetate and beta-hydroxybutyrate in a single channel of the "Multistat III" centrifugal analyzer. Acetoacetate is first reduced with high concentrations of NADH by catalysis with 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30). This reaction mixture is diluted with excess NAD+. The endogenous beta-hydro...

A number of investigators (1) have attempted to explain the decreased utilization of carbohydrate in conditions accompanying food intakes low in carbohydrate and high in fat. In the case of the formation of increased amounts of ketone bodies due to such conditions or to diabetes, Nath and Brahmachari (2) have attributed at least a part of the decreased utilization of carbohydrate to an inactiva...

1. The injection of L-alanine (50-100 mg/kg) into 35-day-old rats that had been starveed for 48 h increased blood L-alanine concentration to values observed in fed animals and lowered the blood concentration of 3-hydroxybutyrate within 2 min. 2. This hypoketon aemic action of L-alanine was specific for 3-hydroxybutyrate, since the acetoacetate concentrations did not change significantly. 3. The...

A series of experiments was performed during the induction of starvation ketosis and in the acute reversal of the ketotic state. In contrast to the predictions of two widely held theories of ketogenesis, control of acetoacetate production by the liver appeared to be unrelated to changes in fatty acid mobilization from the periphery, fatty acid oxidation, fatty acid synthesis, or the acetyl coen...

BACKGROUND Aerobic training has some benefits for delaying the onset or progression of Alzheimer's disease (AD). Little is known about the implication of the brain's two main fuels, glucose and ketones (acetoacetate), associated with thesebenefits. OBJECTIVE To determine whether aerobic exercise training modifies brain energy metabolism in mild AD. METHODS In this uncontrolled study, ten pa...

OBJECTIVE The age-related effects of fasting on lipolysis, the production of ketone bodies, and plasma insulin levels were studied in male 3-, 8-, and 32-week-old Sprague-Dawley rats. METHODS The rats were divided into fasting and control groups. The 3-, 8- and 32-week-old rats tolerated fasting for 2, 5, and 12 days, respectively. RESULTS Fasting markedly reduced the weights of perirenal a...

Acetone is activated by aerobic and nitrate-reducing bacteria via an ATP-dependent carboxylation reaction to form acetoacetate as the first reaction product. In the activation of acetone by sulfate-reducing bacteria, acetoacetate has not been found to be an intermediate. Here, we present evidence of a carbonylation reaction as the initial step in the activation of acetone by the strictly anaero...

Although it is well established that leucine gives rise to ketone bodies in the course of its metabolism in the mammalian organism, the mechanism of this transformation has not been fully elucidated. As early as 1906, Embden and his colleagues (2) presented evidence from perfusion studies that isovaleric acid is a ketogenic substance, and they proposed it as a possible intermediate in the biolo...

Eight ruminally cannulated Holstein bull calves were used in a switchback design to evaluate effects of hay on postprandial changes in ruminal pH, ammonia and VFA, blood ketones, and plasma glucose, NEFA, VFA, and urea N. Calves were fed 4.5 kd/d of calf starter with or without hay for ad libitum consumption. Blood and ruminal fluid were sampled every 2 h for 12 h on d 21 (periods 1 and 2) or d...

FAH (fumarylacetoacetate hydrolase) catalyses the final step of tyrosine catabolism to produce fumarate and acetoacetate. HT1 (hereditary tyrosinaemia type 1) results from deficiency of this enzyme. Previously, we prepared a partial mimic of the putative tetrahedral intermediate in the reaction catalysed by FAH co-crystallized with the enzyme to reveal details of the mechanism [Bateman, Bhanumo...