Manipulations of the metabolic response for management of patients with severe surgical illness: review

Cytokine removal with high cut-off membrane: review of literature

During the last decade, blood purification therapies have been proposed as an effective therapy to control the cytokines dysregulation in systemic inflammatory syndromes. Among them, the treatment with high cut-off membranes is characterized by larger pore size and more effective clearance for middle molecular weight molecules (cytokines). In this paper, we performed a thoughtful review of the literature on HCO being used for blood purification indications in all systemic inflammation syndromes. Clinical and experimental studies show that the use of high effluent flows in a pure diffusive treatment effectively removes serum cytokines with a safe profile in albumin clearance. In clinical studies, the removal of these inflammatory mediators is associated with a significant improvement in hemodynamic condition, oxygenation indices, and organ dysfunction.

Fluids and gastrointestinal function

PURPOSE OF REVIEW

To highlight recent developments relating perioperative fluid therapy to gastrointestinal function by reviewing clinically pertinent English language articles mainly from January 2010 to March 2011.

RECENT FINDINGS

The control of fluid and electrolyte balance involves multiple processes in which the gastrointestinal tract plays an integral role. Diseases affecting the gastrointestinal tract commonly cause fluid and electrolyte disturbance. Similarly, intravenous fluid therapy in the perioperative period can affect gastrointestinal function and have a bearing on postoperative outcome. Striking a balance, in terms of both fluid composition and volume, is likely to reduce the morbidity associated with interstitial edema, a frequently observed occurrence with contemporary perioperative fluid regimens. This balance may be best achieved using individualized and goal-directed approaches to fluid therapy, in order to provide fluid when it is needed and in the correct quantities.

SUMMARY

In planning strategies of fluid therapy, the possibility of adverse effects on the gastrointestinal tract should be considered, as this is likely to have an impact on fluid and electrolyte balance and postoperative outcome.

Na+-dependent neutral amino acid transporter ASCT2 is downregulated in seriously traumatized human intestinal epithelial cells

OBJECTIVE

Serious trauma to the body often is associated with changes in protein metabolism in multiple organs and tissues. Clinically, the catabolic response results in a generalized negative nitrogen balance. Nutrition support has been an important component of the care of seriously traumatized patients. However, during states of severe trauma, enterocyte transport function remains unclear. This study aims to quantitate the Na+-dependent neutral amino acid transport and expression of its transporter in traumatically injured Caco-2 cell lines.

MATERIALS AND METHODS

Transport and transporter of Na+-dependent neutral amino acid in Caco-2 cell lines were characterized. Then the cell lines were cultured under hypoxic, nutrient-deprived, and ischemic conditions for 1, 2, 4, and 6 hours. After severe trauma was performed, we investigated the transport of Na+-dependent neutral amino acids and the expression of transporter protein and mRNA in apical membrane vesicles.

RESULTS

Among the neutral amino acid transporters, only ASCT2 mRNA was amplified successfully. Under nutrient-deprived and ischemic conditions, transport of L-alanine and L-glutamine decreased significantly compared with control (P < 0.01), whereas hypoxia had no significant effect. The changes were associated with a decrease in maximum transport velocity without an influence on transport affinity. Expression of relative transporter proteins and mRNA decreased significantly compared with control (P < 0.01).

CONCLUSIONS

Na+-dependent neutral amino acid transport and its key transporter are differently regulated during state of traumatic injury. It may be of use to provide some strategies targeting the special nutrient requirements and transport capabilities of seriously traumatized patients.

Glutamine 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. Glutamine acts as the preferred respiratory fuel for lymphocytes, hepatocytes and intestinal mucosal cells and is metabolized in the gut to citrulline, ammonium and other amino acids. Low concentrations of glutamine in plasma reflect reduced stores in muscle and this reduced availability of glutamine in the catabolic state seems to correlate with increased morbidity and mortality. Adding glutamine to the nutrition of clinical patients, enterally or parenterally, may reduce morbidity. 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.