The biosynthesis of ribose and deoxyribose in Escherichia coli involves both the oxidative pathway through 6-phosphogluconate and the nonoxidative pathway through the transketolase and transaldolase sequence (Lanning and Cohen, 1954; Bernstein, 1956; Bagatell, Wright, and Sable, 1959). The proportions of the oxidative and nonoxidative pathways depend on the nature of the principal carbon source...

Onset of intracellular acidosis during muscular exercise has been generally attributed to activation or hyperactivation of nonoxidative ATP production but has not been analyzed quantitatively in terms of H(+) balance, i.e., production and removal mechanisms. To address this issue, we have analyzed the relation of intracellular acidosis to H(+) balance during exercise bouts in seven healthy subj...

Lipid infusions may affect glucose tolerance by effects on glucose production or utilization. We performed double-labeled oral glucose tolerance tests with and without a lipid infusion in eight normal subjects. During the lipid infusion, plasma glucose and insulin levels were higher, showing some insulin resistance. The increased glucose level was due to a higher total glucose appearance rate, ...

The effects of fasting on the pathways of insulin-stimulated glucose disposal were explored in three groups of seven normal subjects. Group 1 was submitted to a euglycemic hyperinsulinemic clamp (∼100 μU/ml) after both a 12-h and a 4-day fast. The combined use of [3-3H]- and [U-14C]glucose allowed us to demonstrate that fasting inhibits, by ∼50%, glucose disposal, glycolysis, glucose oxidation,...

Obesity-related diseases now threaten to reach epidemic proportions in the United States. Here we review in a rodent model of genetic obesity, the fa/fa Zucker diabetic fatty (ZDF) rat, the mechanisms involved in the most common complications of diet-induced human obesity, i.e., noninsulin-dependent diabetes mellitus, and myocardial dysfunction. In ZDF rats, hyperphagia leads to hyperinsulinemi...

An important early step in atherosclerosis is binding of apolipoprotein B-100 (apoB-100)– containing lipoproteins (VLDL, IDL, and LDL) to the proteoglycan component of the extracellular matrix of the arterial intima.1,2 When oxidative agents or enzymes attack the proteoglycan-bound lipoproteins, they become oxidatively modified, and when various intimal proteases or lipases hydrolyze them, they...

The effects of mild stress on nonoxidative glucose metabolism were studied in the brain of the freely moving rat. Extracellular lactate levels in the hippocampus and striatum were monitored at 2.5-min intervals with microdialysis coupled with an enzyme-based flow injection analysis system. Ten minutes of restraint stress led to a 235% increase in extracellular lactate levels in the striatum. A ...