Isolated methylmalonic acidemia/aciduria is caused by complete or partial deficiency of the enzyme methylmalonyl-CoA mutase (mut(0) enzymatic subtype or mut(–) enzymatic subtype, respectively), a defect in the transport or synthesis of its cofactor, adenosyl-cobalamin (cblA, cblB, or cblD variant 2 type), or deficiency of the enzyme methylmalonyl-CoA epimerase. Onset of the manifestations of isolated methylmalonic acidemia/aciduria ranges from the neonatal period to adulthood.
The phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1-DS) is now known to be a continuum that includes the classic phenotype as well as dystonia 9, dystonia 18, atypical childhood absence epilepsy, myoclonic astatic epilepsy, and paroxysmal non-epileptic findings such as intermittent ataxia, choreoathetosis, dystonia, and alternating hemiplegia. The classic phenotype is characterized by infantile-onset seizures, delayed neurologic development, acquired microcephaly, and complex movement disorders.
Deficiency of very long-chain acyl-CoA dehydrogenase (VLCAD), which catalyzes the initial step of mitochondrial β-oxidation of long-chain fatty acids with a chain length of 14 to 20 carbons, is associated with three phenotypes. The severe early-onset cardiac and multi-organ failure form typically presents in the first months of life with hypertrophic or dilated cardiomyopathy, pericardial effusion, and arrhythmias, as well as hypotonia, hepatomegaly, and intermittent hypoglycemia.
The phenotypes of dihydrolipoamide dehydrogenase (DLD) deficiency are an overlapping continuum that ranges from early-onset neurologic manifestations to adult-onset isolated liver involvement. Early-onset DLD deficiency typically manifests as a hypotonic infant with lactic acidosis. Affected infants frequently do not survive their initial metabolic decompensation, or die within the first few years of life during a recurrent metabolic decompensation.
The present studies were performed to elucidate the mechanisms responsible for the impairment of glucose-stimulated insulin secretion observed in fasting. Rats fasted for 48 hr displayed marked impairment in their insulin secretory response to both oral and intravenous glucose. Glucose-stimulated insulin secretion was restored within 24 hr by refeeding; actinomycin D given before refeeding blocked the expected return of normal glucose-stimulated insulin secretion despite adequate food intake.
The hypothesis that clinical and biochemical essential fatty acid deficiency (EFA) might occur from the feeding of eucaloric, fat-free diets was tested in two experiments in healthy men. In Study I, eight men were given fat-free, eucaloric diets containing 80% of calories as glucose and 20% as amino acid hydrolysates by a constant drip over a 24-h period. The diets were fed in succession for periods of 2 wk each, either through a superior vena cava catheter or via a nasogastric tube.
Hepatic outputs of biliary lipids can be measured by intestinal perfusion techniques, either during constant infusion of liquid formula into the duodenum or through-out a 24-hour period during which time three meals are given along with an overnight fast. The purpose of this study was to compare these two methods for estimating secretion of biliary lipids.
The effects of training to various rhythms of intermittent total starvation (ITS) or intermittent protein starvation (IPS) on the plasma glucose and the plasma insulin levels were studied in the growing chicken. Both types of feeding improved the glucose tolerance in spite of a decrease in the insulin response. After an oral glucose load, plasma free fatty acids showed opposite variations to plasma insulin and plasma glucose. The insulin released in response to a test meal was unchanged.
1. Defined jejunal segments were perfused with solutions of bile salts and of ricinoleic acid during fasting and after feeding in two groups of conscious dogs, one with the segment in continuity, and the other with a Thirty-Vella loop. Myoelectric activity was recorded from chronically implanted electrodes on the jejunal segment and also from the proximal and distal in situ bowel.2. The results in both groups were identical.