The presence of a food-entrainable oscillator (FEO) independent from the SCN is now well established, but until now its location and characterization have been elusive. Because its expression requires priming of the animal's metabolism toward a catabolic state, it is possible that metabolic rhythms may be related to FEO. The present study was designed to determine whether metabolic rhythms pers...

Type-1 diabetic patients experience hyperketonemia caused by an increase in fatty acid metabolism. Thus, the aim of this study was to measure the effect of ketone bodies as suppressors of oxidizing species produced by stimulated neutrophils. Both acetoacetate and 3-hydroxybutyrate have suppressive effect on the respiratory burst measured by luminol-enhanced chemiluminescence. Through measuremen...

Many workers have demonstrated that extrahepatic tissues utilize ketone bodies in the absence of insulin (1). However, it has been postulated that a decrease in peripheral utilization of ketone bodies is a contributory factor in diabetic ketosis (2). No careful comparison of peripheral utilization by muscle from diabetic and nondiabetic preparations has been reported using modern techniques. Th...

At extreme altitude (>5,000 - 5,500 m), sustained hypoxia threatens human function and survival, and is associated with marked involuntary weight loss (cachexia). This seems to be a coordinated response: appetite and protein synthesis are suppressed, and muscle catabolism promoted. We hypothesise that, rather than simply being pathophysiological dysregulation, this cachexia is protective. Keton...

Caloric restriction (CR) has been shown to increase the life span and health span of a broad range of species. However, CR effects on in vivo brain functions are far from explored. In this study, we used multimetric neuroimaging methods to characterize the CR-induced changes of brain metabolic and vascular functions in aging rats. We found that old rats (24 months of age) with CR diet had reduc...

1. When studied in vitro, tissue from the caecum and the proximal colon of rabbits converted butyrate into ketone bodies. The conversion was similar to that observed with liver slices. The ketogenic activity was associated with the mucosa rather than the muscle of the gut wall and, in the colon, diminished as the distance from the caecal-colonic junction increased. 2. Tissue from the wall of th...

Ketone bodies are neuroprotective in neurological disorders such as epilepsy. We randomly studied nine healthy human subjects twice-with and without continuous infusion of 3-hydroxybutyrate-to define potential underlying mechanisms, assessed regionally (parietal, occipital, temporal, cortical grey, and frontal) by PET scan. During 3-hydroxybutyrate infusions concentrations increased to 5.5±0.4 ...

A gas chromatography-mass spectrometry (GC-MS) method for determination of ketone bodies (β-hydroxybutyrate, acetone, and acetoacetate) in blood is presented. The method is based on enzymatic oxidation of D-β-hydroxybutyrate to acetoacetate, followed by decarboxylation to acetone, which was quantified by the use of headspace GC-MS using acetone-(13)C(3) as an internal standard. The developed me...

The metabolism of millimolar concentrations of R- or S-1,3-butanediol has been studied in perfused livers from fed and starved rats. Protocols were designed to measure in the same experiment (i) uptake of the diol, (ii) the contribution of the diol to ketogenesis, (iii) the contribution of the diol to total fatty acid plus sterol synthesis, and (iv) conversion of S-1,3-butanediol into S-3-hydro...

Role of the liver in glyceride metabolism In mammals, there are three major forms of circulating lipid or lipid-related fuel, free fatty acid (FFA), triglyceride (TG) and ketone bodies. The liver utilizes FFA, and releases T G and ketone bodies. Constituents of the pool of carbohydrate plus amino acids can undergo net conversion to acetyl residues and then to fatty acids (FA) (FA synthesis ‘de ...