| 4 | Glutamine-(dipeptides)-an update显示文摘A) What should be known about supplemental glutamine-(dipeptides) ?In numerous controled clinical trials it could be convincingly demonstrated that supp1emental glutamine- (di pep t ide ) nutrt ion was associated with improved nitrogen balance and mdri; increased protein synthesis and lyTnphocyte count (total and subpopulation); maintained intestinal function, intracellular muscel free glutamine Pool,gut permeability and function, reduced 3MeHis excretion, morbidity, length of hoSPital stay and sepsis frequency. A current European multi center study with ala-gln provides convincing evidence that the clinical use of glutamine dipeptide spares nitrogen and shortens length of hospital stay as compared with the controls. The infusion of the glutamine containing dipeptide soution was free of any side effects, and recovery was normal for each patient. Provision of glutamine- (dipepti de ) should be consi dered as a replacement of a de fic iency rat her t han a supplement. This implies that the beneficial effects observed are due to a correction of disadvantages preduced by an inadequacy of conventional nutrition.B)What is new in glutamine (dipeptide) research?1)It is pu^ed that tissue g1utathione synthesis is a crucial factor in causing reversal of the clinical,biochemical signs of critical illness, a condition associated with decreased glutathione status. lndeed, the decreased ratio GSH/Gase suggests oxidative stress in the tissues. In the future, glutamine containing dipeptides will certainly serve as a means to maintain and/or restore tissue glutathione con centrations.2)Modification of the endogenous inflammatory response:attenuation of the elaboration of prcrinnammatory mediators, upregulation of antiinflammatory factors, improved immune respo~. Studies are in progress showing that supplemental glutamine containing dipeptides decrease cytotoxicity and the synthesis of TNFo and IL8 while they enhance the ability to express the anti-innammatory ILlo. An encouraging persPeCtive is the novel finding that provision of alanyl-glutamine promotes the synthesis of cysteinyl-leukotrienes and that the capacity to generate cysteinylleukorienes is miated with the outcome, serving as a biomarker for survival. The question might be raisd, whether the combined deficiency of gluathione and glutamine is intrinsically related to the leukotriene synthesizing capacity of the sick cell. These factors might be mediated.through enhanced synthesis of glutathione.3) Growth factors glutamine- (dipeptide ) interactionrepresents a nwe strategy to enhance the efficacy of glutamine-(dipeptide) nutrition. Growth factors to consider: human growth hormone,insulin-like growth factor 1 and epidermal growth factor 4) A novel method enabling accurate measurements of protein-bound glutamine in protein or peptide-based enteral diets. The knowedge of glutamine content in various proteins facilitates revision of tissue/organ glutamine kinetics. C)How to use glutamine (dipeptides) in routine clinicial setting?Major questions: which patients ,when to start, how much, how long to administer, which route of administration, how to monitor efficacy?Outlook Future implicatdris of glutamine (dipeptide) therapy are full of promise. A consistent observation is that glutamine (dipeptide)enriched Parenteral feecling attenuates the stressinduced expansion of extracellular and total they water membrane function and thereby changing the cellular hydration state. ExPerimental studies suggest that glutamine availability is an essential factor during conditions aareiated with gluare intolerance, blunting insulin action on glucose preduction and enhanced iusulin-mediated g1ucose uti1ization. A further fascinating approach proopes glutamine (dipePtides) as a suitable cardioprotective and rescue agent. The mechanism through which glutamine exera its beneficial effects may involve maintenance of myoCardial glutamate and thus glutathione as well as myocardial high energy phocphates and prevention of myocardial lactate accumulation. Supplemental glutamine (dipeptide) might thus | Peter Furst, MD, PhD, (University of Hohenheim, Institute of Biological Chemistry & Nutrition, Stuttgart(德国) | 2000 | 中国临床营养杂志2000，8，1： | 0 |
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