High anabolic potential of essential amino acid mixtures in advanced nonsmall cell lung cancer.

BACKGROUND: Conventional nutritional supplements are not or only partly successful in inducing protein accretion in advanced cancer, suggesting an attenuated anabolic response. To prevent muscle wasting and its deleterious consequences, generating an anabolic response is crucial. Dietary essential amino acids (EAA) have anabolic properties in other wasting diseases; however, data in advanced cancer are lacking. PATIENTS AND METHODS: In 13 patients with advanced nonsmall-cell lung cancer (NSCLC) (stage III and IV) and 11 healthy age-matched subjects, we measured protein synthesis and breakdown of the whole body, and net protein anabolism (difference between protein synthesis and breakdown) after intake of 14 g of free EAA with high leucine levels (EAA/leucine) versus a balanced amino acid mixture containing both EAA and non-EAA as present in whey protein, according to a randomized, double-blind, crossover design. RESULTS: Protein synthesis and net protein anabolism were higher after intake of the EAA/leucine than the balanced amino acid mixture (P < 0.001), independent of presence of cancer. A highly significant linear relationship between net protein anabolism and the amount of EAA available in the systemic circulation (R(2): 0.85, P < 0.001) was found in both groups. The presence of muscle or recent weight loss, systemic inflammatory response, or length of survival did not influence this relationship. High leucine levels in the EAA/leucine mixture was of no anabolic benefit. CONCLUSIONS: There is no anabolic resistance or attenuated anabolic potential to intake of 14 g of EAA/leucine or balanced amino acid mixture in advanced (mainly stage III) NSCLC. The high anabolic potential of dietary EAA in cancer patients is independent of their nutritional status, systemic inflammatory response or disease trajectory, suggesting a key role of EAA in new nutritional approaches to prevent muscle loss, thereby improving outcome of patients with advanced cancer. CLINICALTRAILSGOV: NCT01172314.

Acute endotoxemia following transjugular intrahepatic stent-shunt insertion is associated with systemic and cerebral vasodilatation with increased whole body nitric oxide production in critically ill cirrhotic patients.

BACKGROUND & AIMS: Transjugular intrahepatic stent-shunt (TIPSS) insertion, in patients with uncontrolled gastro-intestinal bleeding, often results in worsening of the systemic hemodynamics which can be associated with intracranial hypertension but the underlying mechanisms are unclear. This study explored the hypothesis that TIPSS insertion results in acute endotoxemia which is associated with increased nitric oxide production resulting in systemic and cerebral vasodilatation. METHODS: Twelve patients with cirrhosis who were undergoing TIPSS for uncontrolled variceal bleeding were studied prior to and 1-h after TIPSS insertion. Changes in cardiac output (CO) and cerebral blood flow (CBF) were measured. NO production was measured using stable isotopes using l-[guanidino-(15)N(2)] arginine and l-[ureido-(13)C;5,5-(2)H(2)] citrulline infusion. The effect of pre- and post-TIPSS plasma on nitric oxide synthase (NOS) activity on human endothelial cell-line (HUVEC) was measured. RESULTS: TIPSS insertion resulted in a significant increase in CO and CBF. Endotoxin and induced neutrophil oxidative burst increased significantly without any significant changes in cytokines. Whole body NO production increased significantly and this was associated with increased iNOS activity in the HUVEC lines. The change in NO production correlated with the changes in CO and CBF. Brain flux of ammonia increased without significant changes in arterial ammonia. CONCLUSIONS: In conclusion, the insertion of TIPSS results in acute endotoxemia which is associated with increased nitric oxide production possibly through an iNOS dependent mechanism which may have important pathophysiological and therapeutic relevance to understanding the basis of circulatory failure in the critically ill cirrhotic patient.

Methods using stable isotopes to measure nitric oxide (NO) synthesis in the L-arginine/NO pathway in health and disease.

Nitric oxide (NO) is an important gaseous radical involved in many physiological processes. It is produced from the amino acid L-arginine by the action of nitric oxide synthases (NOS) in what is called the L-arginine/NO pathway. Tracking its metabolic fate in biological fluids is of particular interest as it may indicate how the human body responds in health and disease. However, due to its short life span (a few seconds) it is very difficult to accurately monitor any up- or down-regulation in body fluids in vivo. As a consequence, methods have been developed based on the measurement of the NO-derived products nitrite and nitrate or on the substrate of NO, L-arginine and its simultaneously generated product, L-citrulline. Considering only a fraction of the endogenous L-arginine pool is used for the synthesis of NO, NO-production cannot be estimated by measuring changes in the concentrations of L-arginine and/or L-citrulline alone. Instead, to estimate NO-related changes in the L-arginine and/or L-citrulline pools a form of tagging these metabolites for the NOS-mediated reaction is required. The application of stable isotopes is an elegant way to track NOS-mediated changes. The present paper is focussed on the application of various combinations of chromatography and mass spectrometry to measure isotopic enrichments resulting from the conversion of L-arginine to NO and L-citrulline in a one-to-one stoichiometry. In addition, the various aspects and principles involved in the application of stable isotopes in metabolic studies in general and the study of the activity of NOS in particular are discussed.

Application of liquid chromatography-mass spectrometry to measure the concentrations and study the synthesis of short chain fatty acids following stable isotope infusions.

A new method involving zinc sulphate deproteinization was developed to study short chain fatty acids (SCFA) production in the colon and subsequent occurrence of SCFA in blood. SCFA were baseline separated in a 30 min cycle using ion-exclusion chromatography and detected by mass spectrometry. Concentrations could be measured down to 10 microM and isotopomeric distributions could be assessed, enabling the conduction of tracer studies to study changes in SCFA synthesis. The applicability of the method was tested in an extensively characterized pig model yielding portal SCFA concentrations ranging from 70 microM (butyric acid) to 150 microM (propionic acid) to 440 microM (acetic acid) prior to butyrate tracer infusion, reaching butyric acid isotopic steady state within 2 h.

Carbohydrates and insulin resistance in clinical nutrition: Recommendations from the ESPEN expert group.

Growing evidence underscores the important role of glycemic control in health and recovery from illness. Carbohydrate ingestion in the diet or administration in nutritional support is mandatory, but carbohydrate intake can adversely affect major body organs and tissues if resulting plasma glucose becomes too high, too low, or highly variable. Plasma glucose control is especially important for patients with conditions such as diabetes or metabolic stress resulting from critical illness or surgery. These patients are particularly in need of glycemic management to help lessen glycemic variability and its negative health consequences when nutritional support is administered. Here we report on recent findings and emerging trends in the field based on an ESPEN workshop held in Venice, Italy, 8-9 November 2015. Evidence was discussed on pathophysiology, clinical impact, and nutritional recommendations for carbohydrate utilization and management in nutritional support. The main conclusions were: a) excess glucose and fructose availability may exacerbate metabolic complications in skeletal muscle, adipose tissue, and liver and can result in negative clinical impact; b) low-glycemic index and high-fiber diets, including specialty products for nutritional support, may provide metabolic and clinical benefits in individuals with obesity, insulin resistance, and diabetes; c) in acute conditions such as surgery and critical illness, insulin resistance and elevated circulating glucose levels have a negative impact on patient outcomes and should be prevented through nutritional and/or pharmacological intervention. In such acute settings, efforts should be implemented towards defining optimal plasma glucose targets, avoiding excessive plasma glucose variability, and optimizing glucose control relative to nutritional support.

ESPEN expert group recommendations for action against cancer-related malnutrition.

Patients with cancer are at particularly high risk for malnutrition because both the disease and its treatments threaten their nutritional status. Yet cancer-related nutritional risk is sometimes overlooked or under-treated by clinicians, patients, and their families. The European Society for Clinical Nutrition and Metabolism (ESPEN) recently published evidence-based guidelines for nutritional care in patients with cancer. In further support of these guidelines, an ESPEN oncology expert group met for a Cancer and Nutrition Workshop in Berlin on October 24 and 25, 2016. The group examined the causes and consequences of cancer-related malnutrition, reviewed treatment approaches currently available, and built the rationale and impetus for clinicians involved with care of patients with cancer to take actions that facilitate nutrition support in practice. The content of this position paper is based on presentations and discussions at the Berlin meeting. The expert group emphasized 3 key steps to update nutritional care for people with cancer: (1) screen all patients with cancer for nutritional risk early in the course of their care, regardless of body mass index and weight history; (2) expand nutrition-related assessment practices to include measures of anorexia, body composition, inflammatory biomarkers, resting energy expenditure, and physical function; (3) use multimodal nutritional interventions with individualized plans, including care focused on increasing nutritional intake, lessening inflammation and hypermetabolic stress, and increasing physical activity.

ESPEN Guidelines on Enteral Nutrition: Intensive care.

Enteral nutrition (EN) via tube feeding is, today, the preferred way of feeding the critically ill patient and an important means of counteracting for the catabolic state induced by severe diseases. These guidelines are intended to give evidence-based recommendations for the use of EN in patients who have a complicated course during their ICU stay, focusing particularly on those who develop a severe inflammatory response, i.e. patients who have failure of at least one organ during their ICU stay. These guidelines were developed by an interdisciplinary expert group in accordance with officially accepted standards and are based on all relevant publications since 1985. They were discussed and accepted in a consensus conference. EN should be given to all ICU patients who are not expected to be taking a full oral diet within three days. It should have begun during the first 24h using a standard high-protein formula. During the acute and initial phases of critical illness an exogenous energy supply in excess of 20-25 kcal/kg BW/day should be avoided, whereas, during recovery, the aim should be to provide values of 25-30 total kcal/kg BW/day. Supplementary parenteral nutrition remains a reserve tool and should be given only to those patients who do not reach their target nutrient intake on EN alone. There is no general indication for immune-modulating formulae in patients with severe illness or sepsis and an APACHE II Score >15. Glutamine should be supplemented in patients suffering from burns or trauma.

Keratinocyte growth factor ameliorates acute graft-versus-host disease in a novel nonmyeloablative haploidentical transplantation model.

Allogeneic stem cell transplantations (SCT) are currently being used as a therapy for hematological malignancies, some solid tumors and nonmalignant bone marrow deficiencies. Nevertheless, clinical applicability is limited due to toxicity of conditioning regimens, graft-versus-host disease (GVHD) and the scarcity of HLA-identical family donors. New concepts are based on nonmyeloablative conditioning to reduce toxicity, prevention or amelioration of GVHD and the use of haploidentical donors to increase donor availability. To combine these requirements, we have developed a nonmyeloablative conditioning regimen, consisting of low-dose total body irradiation and cyclophosphamide-based chemotherapy. In a haploidentical F1 --> F1 mouse model, this nonmyeloablative transplantation protocol resulted in stable full donor chimerism, but also in the development of severe GVHD. Administration of keratinocyte growth factor (KGF) reduced GVHD, evident as reduced weight loss and a lesser degree of dermatitis, compared to saline-treated controls. KGF preserved plasma citrulline and tumor necrosis factor-alpha levels, both indicative for reduced injury to the gastrointestinal tract. This was confirmed by histological findings. At 6 months after transplantation, survival rates were significantly higher in KGF-treated animals as compared to phosphate buffered saline-treated controls. These results indicate that KGF preserves gut integrity and might therefore contribute substantially to reduction of lethal GVHD in (nonmyeloablative) haploidentical transplantation.

Effects of a novel method of acute tryptophan depletion on plasma tryptophan and cognitive performance in healthy volunteers.

RATIONALE: Disorders associated with low levels of serotonin (5-HT) are characterized by mood and cognitive disturbances. Acute tryptophan depletion (ATD) is an established method for lowering 5-HT levels and an important tool to study the effects of reduced 5-HT on mood and cognition in human subjects. The traditional ATD method, i.e., administration of separate amino acids (AAs), has several disadvantages. The AA mixture is costly, unpalatable and associated with gastrointestinal discomfort. OBJECTIVES: The University of Maastricht developed a new and inexpensive method for ATD: a natural collagen protein (CP) mixture with low tryptophan (TRP) content. The reductions in plasma TRP after taking this CP mixture were compared with the reductions achieved taking the traditional AA mixture, and effects on memory and reversal learning were studied. METHODS: Fifteen healthy young volunteers participated in a double-blind, counterbalanced within-subject study. Reversal learning, verbal memory and pattern recognition were assessed at baseline and 3-4 h after taking the CP mixture. RESULTS: The new ATD method significantly reduced plasma TRP by 74% and the ratio between TRP and the other large AAs (TRP/LNAA) by 82%. The placebo mixture did not change these measures. Delayed recognition reaction time on the verbal learning task was increased following ATD. No other cognitive effects were found. CONCLUSIONS: The CP mixture was shown to be an efficient tool for lowering plasma TRP in humans. The validity of this method with regard to behavioral changes remains to be established in healthy, vulnerable and clinical populations.

Acute tryptophan and serotonin depletion using an optimized tryptophan-free protein-carbohydrate mixture in the adult rat.

In contrast to humans, a tryptophan (TRP)-free amino acid (AA) mixture only leads to moderate depletion in plasma TRP levels in adult rats. In this study we evaluated the effects of an acute administration of a TRP-free protein-carbohydrate nutritional mixture in adult male Wistar rats. Plasma amino acid levels were examined at 2 and 4h starting after the first administration. Furthermore, the concentrations of amino acid, serotonin (5-HT), dopamine (DA) and their metabolite (5-hydroxyindolacetic acid (5-HIAA) and 3,4-dihydroxyphenylacetic acid (DOPAC), respectively) were measured within the striatum, hippocampus and cortex. In the TRP depleted animals, the TRP/sigmaLNAA ratio (LNAA: large neutral amino acids) was substantial decreased at 2 and 4h after the first administration of the oral administration (by 71 and 78%, respectively). Four hours after treatment central TRP and 5-HT concentrations were decreased by 50%. Both peripheral and central TRP levels returned to basal values in the group treated with the nutritional mixture supplemented with TRP. Surprisingly, tyrosine levels were also reduced after oral administration of the protein-carbohydrate mixture without affecting central DA concentrations. In conclusion, the TRP-free protein-carbohydrate nutritional mixture appears to be an efficient tool to substantially reduce plasma and central TRP levels in adult rat.

Effects of long-term intravenous and intragastric L-arginine intervention on jejunal motility and visceral nitric oxide production in the hyperdynamic compensated endotoxaemic pig.

Alterations in L-arginine availability and nitric oxide (NO) synthesis in the intestinal muscularis may contribute to disturbed small intestinal motility that is observed during endotoxaemia. The aim of this study was to evaluate the effect of L-arginine infusion on visceral NO production and jejunal motility in hyperdynamic compensated endotoxaemic pigs. Fasted and saline-resuscitated pigs were intravenously infused for 24 h with endotoxin (lipopolysaccharide, 50 ng kg(-1) min(-1)) or saline (n = 6). Endotoxaemic pigs received either intravenous L-arginine (n = 6, 5.3 micromol kg(-1) min(-1)) or L-alanine (isocaloric, n = 6). After 24 h, intravenous L-arginine or L-alanine infusion was continued intragastrically for 32-h in an enteral meal. During (0-24 h) and 1 day postendotoxaemia (48-56 h), jejunal motility was recorded by manometry and analysed for migrating motor complex (MMC) characteristics. Visceral NO production was measured at 24 and 48 h by 15N2-arginine-to-15N-citrulline conversion. Visceral NO production was increased during endotoxaemia and was higher in L-arginine than in L-alanine-treated pigs. One day postendotoxaemia, visceral NO synthesis was still increased in L-arginine but not in L-alanine-treated animals. Endotoxaemia shortened the MMC cycle duration and accelerated the MMC propagation velocity. Both were restored by L-arginine. Similar motility disturbances were observed one day postendotoxaemia and were also compensated by L-arginine infusion.

Reduced arginine availability and nitric oxide production.

The precursor for nitric oxide (NO) synthesis is the amino acid arginine. Reduced arginine availability may limit NO production. Arginine availability for NO synthesis may be regulated by de novo arginine production from citrulline, arginine transport across the cell membrane, and arginine breakdown by arginase.

Differential effects of selective and non-selective NOS inhibition on renal arginine and protein metabolism during endotoxemia in rats.

BACKGROUND AND AIMS: The kidney is the main endogenous producer of circulating arginine. Renal arginine disposal is directed to protein synthesis, urea production and nitric oxide synthesis. The administration of nitric oxide synthase inhibitors during sepsis may be beneficial or detrimental depending on the specificity of the inhibitor. We aimed to measure the effects of two NOS inhibitors, with different specificity, on renal arginine and protein turnover in a rat model of sepsis. METHODS: Rats were subject to double hit endotoxemia and either L-NAME (non-specific), SMT (iNOS specific) or saline. Under anesthesia, vessels supplying and draining the kidney were catheterized. Systemic and intra-renal arginine and protein metabolism were measured using a primed continuous infusion of L-[2,3-(3)H]arginine and L-[2,6-(3)H]phenylalanine. RESULTS: Non-specific NOS reduced systemic protein and arginine turnover, whereas selective iNOS inhibition did not. In the kidney, blood flow was reduced by L-NAME, but not by SMT. In conjunction with this, non-selective NOS inhibition increased renal protein breakdown, whereas selective iNOS inhibition increased renal arginine production. CONCLUSIONS: This study shows that non-selective NOS inhibition using L-NAME is detrimental for systemic and renal protein metabolism. Selective NOS inhibition stimulates renal arginine synthesis, without changing circulating arginine levels.

Free amino-acid concentrations in the equine placenta: relationship to maternal and fetal plasma concentrations.

Free amino-acid concentrations were measured in maternal venous and fetal umbilical vein plasma, and in the allantochorion, of Thoroughbred mares at term. Concentrations in maternal and fetal plasma were similar to those reported previously in equids. The concentrations of free amino-acids in the allantochorion were higher than those in the maternal and fetal plasmas and were characterised by high levels of the nonessential amino-acids as observed in other species. Fourteen of the 20 amino-acids measured had similar allantochorion/umbilical vein concentration ratios suggesting that simple gradient diffusion might play a part in their transfer from the placenta to the fetus.

Increased whole body hydroxyproline production as assessed by a new stable isotope technique is associated with hip and spine bone mineral loss in cystic fibrosis.

BACKGROUND & AIMS: Bone mineral loss, reduced lung function and impaired nutritional status are frequently present in children with Cystic Fibrosis (CF). Blood concentrations and urinary excretion of hydroxyproline (OH-PRO) have been used as markers of bone mineral status and lung function in CF. OBJECTIVE: To examine whether whole body hydroxyproline production, as assessed by a new stable isotope methodology, is increased in pediatric patients with CF and associated with bone mineral loss, lung function decline and impaired nutritional status. DESIGN: In a cross-sectional study in 15 pediatric patients with CF and 17 healthy young control subjects, whole body hydroxyproline production (Wb OH-PRO) was assessed in the postabsorptive state by primed-constant and continuous infusion of the stable isotope 2-D-OH-PRO for 3 h. Bone mineral density (BMD) of whole body, hip and spin, and body composition (fat mass and fat-free mass) were determined by dual-energy X-ray Absorptiometry (DXA). Plasma isotopic enrichments and OH-PRO concentrations were measured by LC/MS/MS. RESULTS: Higher values for WbOH-PRO production and plasma OH-PRO concentrations were found in pediatric CF patients than in the healthy young subjects (p < 0.001). WbOH-PRO production was significantly correlated with plasma OH-PRO concentrations in the CF (r: 0.70, p = 0.007) but not in the healthy group. WbOH-PRO production in CF was associated with low BMD values in hip (r = -0.61, p = 0.02) and spine (r = -0.59, p = 0.02) but not with whole body BMD, lung function or body composition. CONCLUSION: A new stable isotope approach revealed enhanced levels of whole body hydroxyproline production rate in pediatric patients with CF, indicative of enhanced whole body collagen breakdown. Increased levels for whole body hydroxyproline production in CF were associated with severe bone mineral loss in hip and spine but not with lung function decline or impaired nutritional status. Registration ClinicalTrials.gov = NCT01172301.

New stable isotope method to measure protein digestibility and response to pancreatic enzyme intake in cystic fibrosis.

BACKGROUND & AIMS: Adequate protein intake and digestion are necessary to prevent muscle wasting in cystic fibrosis (CF). Accurate and easy-to-use methodology to quantify protein maldigestion is lacking in CF. OBJECTIVE: To measure protein digestibility and the response to pancreatic enzyme intake in CF by using a new stable isotope methodology. DESIGN: In 19 CF and 8 healthy subjects, protein digestibility was quantified during continuous (sip) feeding for 6 h by adding (15)N-labeled spirulina protein and L-[ring-(2)H5]phenylalanine (PHE) to the nutrition and measuring plasma ratio [(15)N]PHE to [(2)H5]PHE. Pancreatic enzymes were ingested after 2 h in CF and the response in protein digestibility was assessed. To exclude difference in mucosal function, postabsorptive whole-body citrulline (CIT) production rate was measured by L-[5-(13)C-5,5-(2)H2]-CIT pulse and blood samples were taken to analyze tracer-tracee ratios. RESULTS: Protein digestibility was severely reduced in the CF group (47% of healthy subjects; P < 0.001). Intake of pancreatic enzymes induced a slow increase in protein digestibility in CF until 90% of values obtained by healthy subjects. Maximal digestibility was reached at 100 min and maintained for 80 min. Stratification into CF children (n = 10) and adults showed comparable values for protein digestibility and similar kinetic responses to pancreatic enzyme intake. Whole-body citrulline production was elevated in CF indicating preserved mucosal function. CONCLUSION: Protein digestibility is severely compromised in patients with CF as measured by this novel and easy-to-use stable isotope approach. Pancreatic enzymes are able to normalize protein digestibility in CF, albeit with a severe delay. Registration ClinicalTrials.gov = NCT01494909.

Enhanced anabolic response to milk protein sip feeding in elderly subjects with COPD is associated with a reduced splanchnic extraction of multiple amino acids.

BACKGROUND & AIMS: We previously observed in elderly subjects with Chronic Obstructive Pulmonary Disease (COPD) an enhanced anabolic response to milk protein sip feeding, associated with reduced splanchnic extraction (SPE) of phenylalanine. Milk proteins are known for their high Branched-chain Amino Acids (BCAA) content, but no information is present about splanchnic extraction and metabolism of the individual BCAA in COPD. OBJECTIVE: To investigate whether BCAA metabolism and SPE of the individual BCAA are altered in COPD during milk protein sip feeding. DESIGN: In elderly subjects with COPD and in healthy age-matched elderly SPE, endogenous rate of appearance (Raendo) of the leucine (LEU), isoleucine (ILE) and valine (VAL) were measured before and during sip feeding of a Whey protein meal. To study the effect of aging, the healthy elderly were compared to a group of healthy young subjects. Stable isotopes of l-[(2)H(3)]-LEU, l-[1-(13)C]-ILE and l-[1-(13)C]-VAL were given on two separate test days orally or intravenously. Simultaneously, l-[ring-(2)H(5)]-phenylalanine (PHE) and l-[ring-(2)H(2)]-tyrosine (TYR) were given to determine the whole body protein breakdown (WbPB), synthesis (WbPS) and NetPS. RESULTS: SPE of all BCAA, TYR, and PHE (p < 0.01) were lower in the COPD group, and the increase in netPS during feeding was higher in the COPD group (P < 0.01) due to higher values for PS (P < 0.001). Raendo of all BCAA, PHE and TYR were higher in the COPD than the healthy elderly group (P < 0.05) before and during feeding (P < 0.001). Sip feeding resulted in a reduction of Raendo of PHE, ILE and VAL (P < 0.05). Postabsorptive Raendo was not different for any of the measured amino acids between the healthy elderly and young group, while sip feeding resulted in a reduction of Raendo of PHE. Only SPE of TYR was higher in the elderly (P < 0.05) and the increase in netPS during sip feeding was independent of aging. CONCLUSION: The enhanced anabolic response to milk protein sip feeding in normal-weight COPD patients is associated with a reduced splanchnic extraction of multiple amino acids including all branched-chain amino acids. Registration ClinicalTrials.gov = NCT01418469.