The Journal of nutrition
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The Journal of nutrition · Sep 2001
Calcium fractional absorption and metabolism assessed using stable isotopes differ between postpartum and never pregnant women.
Determining the fractional absorption (FA) of calcium using the incorporation into urine of stable isotopes given intravenously (IV) and orally has become a routine procedure. We investigated the FA of calcium in two groups of (2-3 mo) postpartum women lactating (LACT) (n = 6) and nonlactating (PPNL) (n = 6), and in never pregnant (NP) women (n = 7). The women consumed a controlled diet containing 30-33 mmol/d calcium (Ca) for 21 d. ⋯ The postpartum LACT and PPNL women had a reduced urinary excretion of calcium (P < 0.01) compared with the NP women. There was a significantly greater incorporation (P < 0.001) by LACT women of the oral isotope dose into milk than into urine. Calcium FA can be determined from incorporation of stable isotopes into breast milk and serum as well as urine.
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The Journal of nutrition · Sep 2001
Review Comparative StudyGlutamine alimentation in catabolic state.
Glutamine should be reclassified as a conditionally essential amino acid in the catabolic state because the body's glutamine expenditures exceed synthesis and low glutamine levels in plasma are associated with poor clinical outcome. After severe stress, several amino acids are mobilized from muscle tissue to supply energy and substrate to the host. Glutamine is one of the most important amino acids that provide this function. ⋯ Several excellent clinical trials have been performed to prove efficacy and feasibility of the use of glutamine supplementation in parenteral and enteral nutrition. The increased intake of glutamine has resulted in lower septic morbidity in certain critically ill patient populations. This review will focus on the efficacy and the importance of glutamine supplementation in diverse catabolic states.
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The Journal of nutrition · Sep 2001
ReviewGlutamine supplementation in cancer patients receiving bone marrow transplantation and high dose chemotherapy.
Glutamine supplementation of enteral and parenteral nutrition support has received increased attention in the research community over the past decade. Glutamine may become a conditionally essential nutrient during certain catabolic states, including after bone marrow transplantation (BMT). The administration of enteral or parenteral glutamine seems safe and also potentially efficacious in some patient groups undergoing intensive treatment for cancer. ⋯ Although not all studies demonstrate benefit, there are sufficient positive data to suggest that this nutrient should be considered in the metabolic support of many individuals undergoing the catabolic process of marrow transplantation. Given the available data, randomized, double-blind, controlled clinical trials of glutamine-enriched nutrition in patients receiving BMT and high dose chemotherapy protocols are indicated to further define the utility of this amino acid as adjunctive therapy. Studies of glutamine nutrition combined with current combinations of cytoreductive agents and hematopoietic growth factors in BMT will be particularly pertinent.
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Severe infection causes marked derangements in the flow of glutamine among organs, and these changes are accompanied by significant alterations in regional cell membrane transport and intracellular glutamine metabolism. Skeletal muscle, the major repository of glutamine, exhibits a twofold increase in glutamine release during infection, which is associated with a significant increase in endogenous glutamine biosynthesis. Despite an increase in glutamine synthetase activity in skeletal muscle, the intracellular glutamine pool becomes depleted, indicating that release rates exceed rates of synthesis. ⋯ Recent studies suggest that IGF-1 has a direct effect on stimulating glutamine transport across the gut lumen and thus may represent a therapeutic avenue for improving gut nutrition during severe infection. The cells of the immune system (lymphocytes, macrophages) are also major glutamine consumers during inflammatory states in which cell proliferation is increased. Under these conditions, glutamine availability can become rate limiting for key cell functions, such as phagocytosis and antibody production.