Although both transfusion programs were well tolerated, our finding of more frequent major adverse neurologic events in the restrictive RBC-transfusion group suggests that the practice of restrictive transfusions may be harmful to preterm infants.

BACKGROUND-Safe, accurate methods permitting simultaneous and/or repeated measurement of red blood cell (RBC) survival (RCS) are important to investigate pathophysiology and therapy of anemia. Methods using chromium 51 ( 51 Cr) -labeled RBCs are unacceptable for infants, children, and pregnant women. We report RCS measured in vivo using RBCs labeled with several densities of biotin (BioRBCs).

Red cell survival can be measured accurately in humans using enumeration of biotinylated red cells. The method is practical and does not expose the patient to radiation.

Progressive multiple sclerosis (MS) is a severely disabling neurological condition, and an effective treatment is urgently needed. Recently, high-dose biotin has emerged as a promising therapy for affected individuals. Initial clinical data have shown that daily doses of biotin of up to 300 mg can improve objective measures of MS-related disability. In this article, we review the biology of biotin and explore the properties of this ubiquitous coenzyme that may explain the encouraging responses seen in patients with progressive MS. The gradual worsening of neurological disability in patients with progressive MS is caused by progressive axonal loss or damage. The triggers for axonal loss in MS likely include both inflammatory demyelination of the myelin sheath and primary neurodegeneration caused by a state of virtual hypoxia within the neuron. Accordingly, targeting both these pathological processes could be effective in the treatment of progressive MS. Biotin is an essential co-factor for five carboxylases involved in fatty acid synthesis and energy production. We hypothesize that high-dose biotin is exerting a therapeutic effect in patients with progressive MS through two different and complementary mechanisms: by promoting axonal remyelination by enhancing myelin production and by reducing axonal hypoxia through enhanced energy production. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.

Circulating red cell volume measured by the use of biotin with either 125I-streptavidin or flow cytometry agrees with that measured by 51Cr. Each system provides a method of performing these studies without exposing the subject to radiation.

To assess the utility of various indicators of biotin status, marginal biotin deficiency was induced experimentally in normal adults. Ten subjects consumed a diet that contained enough avidin to bind seven times more biotin than that in the diet. Blood and 24-h urine samples were collected before the diet began and twice weekly thereafter for 20 d. The urinary excretion and serum concentration of biotin and its two principal inactive metabolites bisnorbiotin and biotin sulfoxide were determined after HPLC separation with an avidin-binding assay. The urinary concentration of 3-hydroxyisovaleric acid, an indicator of reduced activity of a biotin-dependent enzyme, was quantitated by gas chromatography-mass spectrometry. The urinary excretion of 3-hydroxyisovaleric acid increased significantly (P < 0.0001). For all subjects, the urinary excretion of both biotin and bisnorbiotin decreased significantly (P < 0.0001 for each). In contrast, the mean serum concentration of biotin did not decrease significantly (P = 0.06). These data provide evidence that the urinary excretion of 3-hydroxyisovaleric acid and the urinary excretion of biotin are early and sensitive indicators of biotin deficiency and that the serum concentration of biotin is not.

No abstract

Background-Most neonates less than 1.0 kg birth weight need red blood cell (RBC) transfusions. Delayed clamping of the umbilical cord 1 minute after delivery transfuses the neonate with autologous placental blood to expand blood volume and provide 60 percent more RBCs than after immediate clamping. This study compared hematologic and clinical effects of delayed versus immediate cord clamping.