l-Alanyl-Glutamine Preoperative Infusion in Patients with Critical Limb Ischemia Subjected to Distal Revascularization Reduces Tissue Damage and Protects from Oxidative Stress

Beetroot as a Potential Functional Food for Cancer Chemoprevention, a Narrative Review

Patients with cancer are prone to several debilitating side effects including fatigue, insomnia, depression and cognitive disturbances. Beetroot (Beta vulgaris L.) as a health promoting functional food may be potentially beneficial in cancer. As a source of polyphenols, flavonoids, dietary nitrates and other useful nutrients, beetroot supplementation may provide a holistic means to prevent cancer and manage undesired effects associated with chemotherapy. The main aim of this narrative review is to discuss beetroot's nutrient composition, current studies on its potential utility in chemoprevention and cancer-related fatigue or treatment-related side effects such as cardiotoxicity. This review aims to provide the current status of knowledge and to identify the related research gaps in this area. The flavonoids and polyphenolic components present in abundance in beetroot support its significant antioxidant and anti-inflammatory capacities. Most in vitro and in vivo studies have shown promising results; however, the molecular mechanisms underlying chemopreventive and chemoprotective effects of beetroot have not been completely elucidated. Although recent clinical trials have shown that beetroot supplementation improves human performance, translational studies on beetroot and its functional benefits in managing fatigue or other symptoms in patients with cancer are still lacking.

Glutamine pretreatment protects bovine mammary epithelial cells from inflammation and oxidative stress induced by γ-d-glutamyl-meso-diaminopimelic acid (iE-DAP)

Glutamine (GLN) has many types of biological activity in rats, including anti-inflammatory, antioxidative stress, and anti-apoptosis effects. However, little is known about the effects of GLN on bovine mammary epithelial cells (BMEC). γ-d-Glutamyl-meso-diaminopimelic acid (iE-DAP) is a cell wall peptidoglycan component of gram-negative bacteria that can be recognized by the intracellular receptor nucleotide-binding oligomerization domain-containing protein 1 (NOD1) and can cause bovine mastitis. The goal of the present study was to investigate whether GLN protects BMEC from iE-DAP-induced inflammation, oxidative stress, and apoptosis. We cultured BMEC in a GLN-free medium for 24 h and then separated them into 4 groups: cells treated with 1× PBS for 26 or 32 h (control); cells stimulated by 10 μg/mL iE-DAP for 2 or 8 h (2- or 8-h iE-DAP); cells pretreated with 8 or 4 mM GLN for 24 h followed by 2 or 8 h of 1× PBS treatment (8 or 4 mM GLN); and cells pretreated with 8 or 4 mM GLN for 24 h followed by 2 or 8 h of iE-DAP treatment (DG). In the 2-h iE-DAP group, when levels of inflammation peaked, iE-DAP treatment increased both the mRNA and protein expression of NOD1, inhibitor of nuclear factor-κB (NFKBIA, IκB), and nuclear factor-κB subunit p65 (RELA, NF-κB p65), as well as the mRNA expression of IL6 and IL8 and levels of IL-6 and tumor necrosis factor-α in cell culture supernatants. In contrast, 8 mM GLN pretreatment inhibited the mRNA and protein expression of inflammatory-related factors by suppressing the NOD1/NF-κB pathway. In the 8-h iE-DAP group, iE-DAP treatment decreased the mRNA and protein expression of extracellular regulated kinase (Erk, ERK) and nuclear factor erythroid 2-associated factor2 (NFE2L2, Nrf2), as well as the mRNA expression of superoxide dismutase 1 (SOD1), catalase (CAT), coenzyme II oxidoreductase 1 (NQO1), and heme oxygenase 1 (HMOX1, HO1). In addition, iE-DAP treatment increased the expression of malondialdehyde in BMEC when oxidative stress levels peaked. Interestingly, 4 mM GLN pretreatment induced the mRNA and protein expression of antioxidative stress-related factors and inhibited the expression of reactive oxygen species in BMEC by promoting the ERK/Nrf2 pathway. Moreover, GLN reduced apoptosis caused by inflammation and oxidative stress in BMEC. This is the first report showing that GLN protects against iE-DAP-induced inflammation and oxidative stress via the NOD1/NF-κB and ERK/Nrf2 pathways in BMEC.

Effects of dietary glutamine supplementation on immune cell polarization and muscle regeneration in diabetic mice with limb ischemia

PURPOSE

Diabetes is a chronic inflammatory disorder resulting in endothelial dysfunction which contributes to peripheral arterial disease and limb ischemia. Leukocytes play critical roles in vascular and tissue remodelling after ischemia. This study investigated the effects of dietary glutamine (GLN) supplementation on immune cell polarization in diabetic mice subjected to limb ischemia.

METHODS

Diabetes was induced by an intraperitoneal injection of streptozotocin for 5 consecutive days in C57BL/6J mice. Diabetic mice were fed the AIN-93 diet or an AIN-93 diet in which a part of the casein was replaced by GLN. After 3 weeks of the dietary intervention, mice were subjected to unilateral femoral artery ligation to induce limb ischemia.

RESULTS

GLN supplementation enhanced the proportion of anti-inflammatory monocytes and regulatory T cells in the blood. Expression of C-C motif chemokine receptor 5 by activated CD4⁺ T cells was promoted and prolonged in the GLN-supplemented group. GLN downregulated the percentage of M1 macrophages in muscle tissues which was correlated with lower levels of C-C motif chemokine ligand 2 in plasma. The muscle M1/M2 ratio was also reduced in the GLN group. Gene expression of interleukin-6 was suppressed by GLN supplementation, while expression levels of the peroxisome proliferator-activated receptor γ and myogenic differentiation 1 genes were elevated in post-ischemic muscles. Histological findings also indicated that muscle regeneration was accelerated in the GLN group.

CONCLUSIONS

GLN supplementation in diabetic mice may exert more-balanced polarization of CD4⁺ T cells, monocytes, and macrophages, thus attenuating inflammatory responses and contributing to muscle regeneration after limb ischemia.

NMR-based metabolomic analysis of the effects of alanyl-glutamine supplementation on C2C12 myoblasts injured by energy deprivation

The dipeptide alanyl-glutamine (Ala-Gln) is a well-known parenteral nutritional supplement. The Ala-Gln supplementation is a potential treatment for muscle-related diseases and injuries. However, molecular mechanisms underlying the polyphenic effects of Ala-Gln supplementation remain elusive. Here, we performed NMR-based metabolomic profiling to analyze the effects of Ala-Gln, and the free alanine (Ala) and glutamine (Gln) supplementations on the mouse myoblast cell line C2C12 injured by glucose and glutamine deprivation. All the three supplementations can promote the differentiation ability of the injured C2C12 cells, while only Ala-Gln supplementation can facilitate the proliferation of the injured cells. Ala-Gln supplementation can partially restore the metabolic profile of C2C12 myoblasts disturbed by glucose and glutamine deprivation, and exhibits more significant effects than Ala and Gln supplementations. Our results suggest that Ala-Gln supplementation can promote MyoD1 protein synthesis, upregulate the muscle ATP-storage phosphocreatine (PCr), maintain TCA cycle anaplerosis, enhance the antioxidant capacity through promoting GSH biosynthesis, and stabilize lipid membranes by suppressing glycerophospholipids metabolism. This work provides new insight into mechanistic understanding of the polyphenic effects of Ala-Gln supplementation on muscle cells injured by energy deprivation.

Glutamine protects intestinal calcium absorption against oxidative stress and apoptosis

The aim of this study was to investigate whether glutamine (GLN) could block the inhibition of the intestinal Ca²⁺ absorption caused by menadione (MEN), and elucidate the underlying mechanisms. To do this, one-month old chicks were divided in four groups: 1) controls, 2) MEN treated, 3) GLN treated and 4) GLN treated before or after MEN treatment. Intestinal Ca²⁺ absorption as well as protein expression of molecules involved in the transcellular Ca²⁺ pathway were determined. Glutathione (GSH) and superoxide anion and activity of enzymes of the antioxidant system were evaluated. Apoptosis was measured by the TUNEL technique, the expression of FAS and FASL and the caspase-3 activity. A previous dose of 0.5gGLN/kg of b.w. was necessary to show its protector effect and a dose of 1g/kg of b.w. could restore the intestinal Ca²⁺ absorption after MEN treatment. GLN alone did not modify the protein expression of calbindin D_28k and plasma membrane Ca²⁺-ATPase, but blocked the inhibitory effect of the quinone. GLN avoided changes in the intestinal redox state provoked by MEN such as a decrease in the GSH content, and increases in the superoxide anion and in the SOD and CAT activities. GLN abrogated apoptotic effects caused by MEN in intestinal mucosa, as indicated by the reduction of TUNEL (+) cells and the FAS/FASL/caspase-3 pathway. In conclusion, GLN could be an oral nutritional supplement to normalize the redox state and the proliferation/cell death ratio in the small intestine improving the intestinal Ca²⁺ absorption altered by oxidative stress.

L-Alanyl-Glutamine Attenuates Oxidative Stress in Liver Transplantation Patients

BACKGROUND

Ischemia/reperfusion injury during liver transplantation can cause severe damage to the graft. The objective of this randomized, double-blind study was to evaluate the possible protective effects of L-alanyl-glutamine on the liver graft.

METHODS

The sample included 33 patients from a liver transplantation service in Northeastern Brazil. Before cold ischemia, the patients received 50 g of L-alanyl-glutamine (treatment group) or saline (control group) through the portal vein. The graft was biopsied at the time of recovery, at the beginning of warm ischemia, and at the end of transplantation to determine malondialdehyde (MDA), heat-shock protein (Hsp)70, nuclear factor kappa-beta (NFkB), superoxide dismutase (SOD), and reduced glutathione (GSH) levels.

RESULTS

The blood parameters were similar in the two groups. In the treatment group, MDA did not increase at the beginning of cold ischemia and decreased at the end of transplantation. This phenomenon was not observed in the control group. GSH, SOD, Hsp70, and NFkB levels were similar in the two groups.

CONCLUSIONS

Our findings suggest that preconditioning with L-alanyl-glutamine attenuates the effects of ischemia/reperfusion-related oxidative stress and reduces lipid peroxidation in the grafts of liver transplantation patients.

The Influence of Manganese and Glutamine Intake on Antioxidants and Neurotransmitter Amino Acids Levels in Rats' Brain

Depending on the concentration, Mn can exert protective or toxic effect. Potential mechanism for manganese neurotoxicity is manganese-induced oxidative stress. Glutamine supplementation could reduce manganese-induced neurotoxicity and is able to influence the neurotransmission processes. The aim of this study was to investigate whether the long term administration of manganese (alone or in combination with glutamine) in dose and time dependent manner could affect the selected parameters of oxidative-antioxidative status (superoxide dismutase and glutathione peroxidase activities, concentrations of vitamin C and malonic dialdehyde) and concentrations of excitatory (Asp, Glu) and inhibitory amino acids (GABA, Gly) in the brain of rats. The experiments were carried out on 2-months-old albino male rats randomly divided into 6 group: Mn300 and Mn500—received solution of MnCl₂ to drink (dose 300 and 500 mg/L, respectively), Gln group—solution of glutamine (4 g/L), Mn300-Gln and Mn500-Gln groups—solution of Mn at 300 and 500 mg/L and Gln at 4 g/L dose. The control group (C) received deionized water. Half of the animals were euthanized after three and the other half—after 6 weeks of experiment. The exposure of rats to Mn in drinking water contributes to diminishing of the antioxidant enzymes activity and the increase in level of lipid peroxidation. Glutamine in the diet admittedly increases SOD and GPx activity, but it is unable to restore the intracellular redox balance. The most significant differences in the examined amino acids levels in comparison to both control and Gln group were observed in the group of rats receiving Mn at 500 mg/L dose alone or with Gln. It seems that Gln is amino acid which could improve antioxidant status and affect the concentrations of the neurotransmitters.

Effects of a New Metabolic Conditioning Supplement on Perioperative Metabolic Stress and Clinical Outcomes: A Randomized, Placebo-Controlled Trial

BACKGROUND

Insulin resistance is a measure of metabolic stress in the perioperative period. Before now, no clinical trial has determined the summative effects of glutamine, L-carnitine, and antioxidants as metabolic conditioning supplements in the perioperative period.

OBJECTIVES

The purpose of this study was to determine the effects of a new conditioning supplement on perioperative metabolic stress and clinical outcomes in non-diabetic patients.

PATIENTS AND METHODS

In this randomized controlled trial, 89 non-diabetic patients scheduled for coronary artery bypass grafting, with ejection fractions above 30%, were selected. Using the balanced block randomization method, the patients were allocated to one of four study arms: 1) SP (supplement/placebo): supplement seven days before and placebo 30 days after the surgery; 2) PS: placebo before and supplement after the surgery; 3) SS: supplement before and after the surgery; and 4) PP: placebo before and after the surgery. The supplement was composed of glutamine, L-carnitine, vitamin C, vitamin E, and selenium, which was manufactured for the first time by this research team. Five blood samples were drawn: seven days preoperatively, at the entrance to the operating room, while leaving the operating room, seven days postoperatively, and 30 days postoperatively. Levels of glucose, insulin, and HbA1c were measured in blood samples. Insulin resistance and sensitivity were calculated using a formula. Surgical complications were assessed 30 days postoperatively. Data analysis was done using one-way ANOVA, the Chi-square test, and a general linear model repeated-measures analysis with Bonferroni adjustment.

RESULTS

Blood glucose levels were increased postoperatively in the four groups (< 0.001), but a significantly higher increase occurred in the PP group compared to the SP (0.027), PS (0.026), and SS (0.004) groups. The superficial wound infection rate was significantly different between the four groups (0.021): 26.08% in PP, 9.09% in SP, 4.54% in PS, and 0% in SS.

CONCLUSIONS

Our new metabolic conditioning supplement, whether given pre- or postoperatively, led to better perioperative glycemic control and decreased postsurgical wound infections in non-diabetic patients.

Bradykinin Impairs and HOE 140 does not Protect Rat Hindlimb Skeletal Muscle Against Tourniquet-induced Reperfusion Injury

BACKGROUND

Bradykinin (BK) is used in different tissues. Dose-dependent studies have demonstrated that low doses protect against ischemia/reperfusion (I/R) injury while higher doses lead to adverse effects. Although the beneficial effects of BK infusion were observed in myocardium, its role on the I/R impact in skeletal muscle (SM) has not been fully clarified.

OBJECTIVE

This study was carried out to evaluate the effects of BK, administered in the hindlimbs of rats subjected to I/R.

METHODS

The study design included three experimental groups: Group 1 control (saline), Group 2 (bradykinin), and Group 3 (HOE 140, a BK2 receptor blocker). In all three groups, rats were subjected to hindlimb ischemia for a total of 2 h followed by continuous 4 h of reperfusion with pharmacological interventions. The methods include analysis of enzymes (lactate dehydrogenase-LDH and creatinine phosphokinase-CPK), cell membrane marker of injury (malondialdeyde-MDA), recruitment of neutrophils (myeloperoxidase-MPO), and apoptosis index (immunohistochemistry TUNEL in situ peroxidase dead end).

RESULTS

Except for the apoptotic index, all parameters studied were shown to be elevated in the reperfusion group intervened with BK. The blocking of BK2 receptors by HOE 140 did not affect the I/R injury.

CONCLUSION

After 2 h of total ischemia, infusion of bradykinin during 4 h of reperfusion, worsened the I/R injury in the hindlimb skeletal muscle.

Supplementation of l-Alanyl-l-Glutamine and Fish Oil Improves Body Composition and Quality of Life in Patients With Chronic Heart Failure

BACKGROUND

Skeletal muscle dysfunction and exercise intolerance are clinical hallmarks of patients with heart failure. These have been linked to a progressive catabolic state, skeletal muscle inflammation, and impaired oxidative metabolism. Previous studies suggest beneficial effects of ω-3 polyunsaturated fatty acids and glutamine on exercise performance and muscle protein balance.

METHODS AND RESULTS

In a randomized double-blind, placebo-controlled trial, 31 patients with heart failure were randomized to either l-alanyl-l-glutamine (8 g/d) and polyunsaturated fatty acid (6.5 g/d) or placebo (safflower oil and milk powder) for 3 months. Cardiopulmonary exercise testing, dual-energy x-ray absorptiometry, 6-minute walk test, hand grip strength, functional muscle testing, echocardiography, and quality of life and lateral quadriceps muscle biopsy were performed at baseline and at follow-up. Oxidative capacity and metabolic gene expression were analyzed on muscle biopsies. No differences in muscle function, echocardiography, 6-minute walk test, or hand grip strength and a nonsignificant increase in peak VO2 in the treatment group were found. Lean body mass increased and quality of life improved in the active treatment group. Molecular analysis revealed no differences in muscle fiber composition, fiber cross-sectional area, gene expression of metabolic marker genes (PGC1α, CPT1, PDK4, and GLUT4), and skeletal muscle oxidative capacity.

CONCLUSIONS

The combined supplementation of l-alanyl-l-glutamine and polyunsaturated fatty acid did not improve exercise performance or muscle function but increased lean body mass and quality of life in patients with chronic stable heart failure. These findings suggest potentially beneficial effects of high-dose nutritional polyunsaturated fatty acids and amino acid supplementations in patients with chronic stable heart failure.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01534663.

Probe-based confocal laser endomicroscopy and fluorescence-based enhanced reality for real-time assessment of intestinal microcirculation in a porcine model of sigmoid ischemia

BACKGROUND AND AIM

Surgeons currently rely on visual clues to estimate the presence of sufficient vascularity for safe anastomosis. We aimed to assess the accuracy of endoluminal confocal laser endomicroscopy (CLE) and laparoscopic fluorescence-based enhanced reality (FLER), using near-infrared imaging and fluorescence from injected Indocyanine Green, to identify the transition from ischemic to vascular areas in a porcine model of mesenteric ischemia.

METHODS

Six pigs underwent 1-h sigmoid segmental ischemia. The ischemic area was evaluated by clinical assessment and FLER to determine presumed viable margins. For each sigmoid colon, 5 regions of interest (ROIs) were identified: ischemic (ROI 1), presumed viable margins ROI 2a (distal) and 2b (proximal), and vascular areas 3a (distal) and 3b (proximal). After injection of fluorescein, CLE scanning of the mucosa from the ischemic area toward viable margins was performed. Capillary blood samples were obtained by puncturing the serosa at the ROIs, and capillary lactates were measured with the EDGE(®) analyzer.

RESULTS

Capillary lactates were significantly higher at ROI 1 (4.91 mmol/L) when compared to resection margins (2.8 mmol/L; mean difference: 2.11; p < 0.05) identified by FLER. There was no significant difference in lactates between ROI1 and resection margins identified by clinical evaluation. In 50 % of cases, ROI 2aCLINIC-2bCLINIC were considered to match (<1 cm distance) with ROI 2aFLER-2bFLER. Confocal analysis revealed specific clues to identify the transition from ischemic to viable areas corresponding to those assessed by FLER in 11/12 cases versus 7/12 for those identified by clinical evaluation.

CONCLUSIONS

In this experimental model, FLER and CLE were more accurate than clinical evaluation to delineate bowel vascularization.

Enhanced-reality video fluorescence: a real-time assessment of intestinal viability

OBJECTIVE

Our aim was to evaluate a fluorescence-based enhanced-reality system to assess intestinal viability in a laparoscopic mesenteric ischemia model.

MATERIALS AND METHODS

A small bowel loop was exposed, and 3 to 4 mesenteric vessels were clipped in 6 pigs. Indocyanine green (ICG) was administered intravenously 15 minutes later. The bowel was illuminated with an incoherent light source laparoscope (D-light-P, KarlStorz). The ICG fluorescence signal was analyzed with Ad Hoc imaging software (VR-RENDER), which provides a digital perfusion cartography that was superimposed to the intraoperative laparoscopic image [augmented reality (AR) synthesis]. Five regions of interest (ROIs) were marked under AR guidance (1, 2a-2b, 3a-3b corresponding to the ischemic, marginal, and vascularized zones, respectively). One hour later, capillary blood samples were obtained by puncturing the bowel serosa at the identified ROIs and lactates were measured using the EDGE analyzer. A surgical biopsy of each intestinal ROI was sent for mitochondrial respiratory rate assessment and for metabolites quantification.

RESULTS

Mean capillary lactate levels were 3.98 (SD = 1.91) versus 1.05 (SD = 0.46) versus 0.74 (SD = 0.34) mmol/L at ROI 1 versus 2a-2b (P = 0.0001) versus 3a-3b (P = 0.0001), respectively. Mean maximal mitochondrial respiratory rate was 104.4 (±21.58) pmolO2/second/mg at the ROI 1 versus 191.1 ± 14.48 (2b, P = 0.03) versus 180.4 ± 16.71 (3a, P = 0.02) versus 199.2 ± 25.21 (3b, P = 0.02). Alanine, choline, ethanolamine, glucose, lactate, myoinositol, phosphocholine, sylloinositol, and valine showed statistically significant different concentrations between ischemic and nonischemic segments.

CONCLUSIONS

Fluorescence-based AR may effectively detect the boundary between the ischemic and the vascularized zones in this experimental model.

FOXO4-knockdown suppresses oxidative stress-induced apoptosis of early pro-angiogenic cells and augments their neovascularization capacities in ischemic limbs

The effects of therapeutic angiogenesis by intramuscular injection of early pro-angiogenic cells (EPCs) to ischemic limbs are unsatisfactory. Oxidative stress in the ischemic limbs may accelerate apoptosis of injected EPCs, leading to less neovascularization. Forkhead transcription factor 4 (FOXO4) was reported to play a pivotal role in apoptosis signaling of EPCs in response to oxidative stress. Accordingly, we assessed whether FOXO4-knockdown EPCs (FOXO4KD-EPCs) could suppress the oxidative stress-induced apoptosis and augment the neovascularization capacity in ischemic limbs. We transfected small interfering RNA targeted against FOXO4 of human EPCs to generate FOXO4KD-EPCs and confirmed a successful knockdown. FOXO4KD-EPCs gained resistance to apoptosis in response to hydrogen peroxide in vitro. Oxidative stress stained by dihydroethidium was stronger for the immunodeficient rat ischemic limb tissue than for the rat non-ischemic one. Although the number of apoptotic EPCs injected into the rat ischemic limb was greater than that of apoptotic EPCs injected into the rat non-ischemic limb, FOXO4KD-EPCs injected into the rat ischemic limb brought less apoptosis and more neovascularization than EPCs. Taken together, the use of FOXO4KD-EPCs with resistance to oxidative stress-induced apoptosis may be a new strategy to augment the effects of therapeutic angiogenesis by intramuscular injection of EPCs.

Oxidative stress parameters in women with breast cancer undergoing neoadjuvant chemotherapy and treated with nutraceutical doses of oral glutamine

PURPOSE

To evaluate the effects of oral administration of GLN on the oxidative stress in women with breast cancer undergoing neoadjuvant FAC chemotherapy (5 fluouracil 500 mg/m²+Doxorubicin 50 mg/m²+Cyclophosphamide 500 mg/m² body surface area).

METHODS

Twenty women (mean age: 51.7 years) with breast ductal carcinomas classified as T3 or T4 were included in the study, regardless of pre or post menopause status. Sachets containing glutamine 15g ("A") or milk protein 15g ("B") were prepared by a registered pharmacist. Allocation of patients was made by software program. Patients who received sachets labeled "A" were included in G1 group. The remaining patients, treated with the preparation labeled "B", were included in group G2. Sachets contents were blended in 150 ml of drinking water, and were given daily to each patient during the entire course of neoadjuvant chemotherapy. Peripheral blood samples were collected in the first day of each of the three cycles of chemotherapy before drug infusion. Tumor and normal breast samples were collected at the end of Patey´s surgical procedure. Samples were analysed for GSH and TBARS contents.

RESULTS

TBARS and GSH values were not different in breast healthy and tumor tissues nor blood when comparing control (G-2) and glutamine-treated (G-1) patients. Also, no significant differences were found in TBARS and GSH levels comparing different timepoints within the same group.

CONCLUSION

Oral GLN (15g/kg/day) offers no protection against systemic or local oxidative stress in women with breast Ca undergoing neoadjuvant chemotherapy (FAC).

Antioxidants and micronutrient supplementation in trauma patients

PURPOSE OF REVIEW

This study reviews important nutrients responsible for oxidant-antioxidant balance in trauma patients requiring admission to the ICU and rationale for repletion of antioxidants using pharmaconutrition.

RECENT FINDINGS

Oxidative stress is an underlying cause of critical illness due to oxidant-antioxidant imbalance. Multiple nutrients important to oxidative balance have been studied, yet much variety exists among the dosing, timing, and route of administration. Conflict also exists regarding the benefits of particular single nutrients and the effects of combination therapy. Anticipated results of the Reducing Deaths due to Oxidative Stress trial hope to provide further insight to the use of antioxidants in critically ill patients.

SUMMARY

The goal of this review, though not exhaustive, serves to highlight recent significant studies regarding antioxidant use in the ICU setting while calling for sufficiently powered randomized, controlled trials to elucidate appropriate guidelines for antioxidant administration in regards to ideal dosing, route of administration, timing of administration, duration of therapy, and the role of single versus combination supplementation.

Metabolic conditioning to attenuate the adverse effects of perioperative fasting and improve patient outcomes

PURPOSE OF REVIEW

To review recent articles, published between October 2009 and September 2011, that examined the adverse metabolic consequences of perioperative fasting and interventions that may be utilized to minimize these effects.

RECENT FINDINGS

Fasting induces metabolic stress and insulin resistance consequent upon effects on cellular mitochondria, gene and protein expression. Development of perioperative insulin resistance leads to increased postoperative morbidity and mortality. Preoperative carbohydrate loading attenuates insulin resistance via effects on cellular gene and protein expression, but its effects on clinical outcomes remain unclear. Perioperative arginine-supplemented diets were shown to be associated with significant reductions in infectious complications and length of hospital stay in patients undergoing elective surgery. Perioperative metabolic conditioning using glutamine and L-carnitine may be used to modulate insulin sensitivity but further studies need to determine whether these interventions result in clinical benefit. Finally, energy and protein provision to critically ill patients remains inadequate and is hampered by a number of factors including reliance on inaccurate means of estimating energy expenditure and enteral feed tolerance, conflicting data on the effects of energy deficit on clinical outcomes, and poor methodological quality of studies of perioperative nutritional interventions.

SUMMARY

Numerous perioperative interventions are available, which if utilized should help attenuate the adverse effects of perioperative fasting and lead to improved patient outcomes.

Effects of glutamine supplementation on oxidative stress-related gene expression and antioxidant properties in rats with streptozotocin-induced type 2 diabetes

There are close links among hyperglycaemia, oxidative stress and diabetic complications. Glutamine (GLN) is an amino acid with immunomodulatory properties. The present study investigated the effect of dietary GLN on oxidative stress-relative gene expressions and tissue oxidative damage in diabetes. There were one normal control (NC) and two diabetic groups in the present study. Diabetes was induced by an intraperitoneal injection of nicotinamide followed by streptozotocin (STZ). Rats in the NC group were fed a regular chow diet. In the two diabetic groups, one group (diabetes mellitus, DM) was fed a common semi-purified diet while the other group received a diet in which part of the casein was replaced by GLN (DM-GLN). GLN provided 25% of total amino acid N. The experimental groups were fed the respective diets for 8 weeks, and then the rats were killed for further analysis. The results showed that blood thioredoxin-interacting protein (Txnip) mRNA expression in the diabetic groups was higher than that in the NC group. Compared with the DM group, the DM-GLN group had lower glutamine fructose-6-phosphate transaminase 1, a receptor of advanced glycation end products, and Txnip gene expressions in blood mononuclear cells. The total antioxidant capacity was lower and antioxidant enzyme activities were altered by the diabetic condition. GLN supplementation increased antioxidant capacity and normalised antioxidant enzyme activities. Also, the renal nitrotyrosine level and Txnip mRNA expression were lower when GLN was administered. These results suggest that dietary GLN supplementation decreases oxidative stress-related gene expression, increases the antioxidant potential and may consequently attenuate renal oxidative damage in rats with STZ-induced diabetes.

Amino acid composition in parenteral nutrition: what is the evidence?

PURPOSE OF REVIEW

Complete parenteral nutrition solutions contain mixed amino acid products providing all nine essential amino acids and a varying composition of nonessential amino acids. Relatively little rigorous comparative efficacy research on altered parenteral nutrition amino acid composition has been published in recent years.

RECENT FINDINGS

Limited data from randomized, double-blind, adequately powered clinical trials to define optimal doses of total or individual amino acids in parenteral nutrition are available. An exception is the growing number of studies on the efficacy of glutamine supplementation of parenteral nutrition or given as a single parenteral agent. Parenteral glutamine appears to confer benefit in selected patients; however, additional data to define optimal glutamine dosing and the patient subgroups who may most benefit from this amino acid are needed. Although some promising studies have been published, little data are available in the current era of nutrition support on the clinical efficacy of altered doses of arginine, branched chain amino acids, cysteine, or taurine supplementation of parenteral nutrition.

SUMMARY

Despite routine use of parenteral nutrition, surprisingly little clinical efficacy data are available to guide total or specific amino acid dosing in adult and pediatric patients requiring this therapy. This warrants increased attention by the research community and funding agencies to better define optimal amino acid administration strategies in patient subgroups requiring parenteral nutrition.