U-Shape Relationship between Plasma Leucine Level and Mortality in the Intensive Care Unit

Patients in the intensive care unit (ICU) are at high risk of mortality which is not well predicted. Previous studies noted that leucine has prognostic value in a variety of diseases. This study investigated whether leucine concentration was a useful biomarker of metabolic and nutritional status and 6-month mortality in ICU. We recruited 454 subjects admitted to ICU (348 and 106 in the initiation and validation cohorts, respectively) with an acute physiology and chronic health evaluation (APACHE II) score ≥ 15 . We measured plasma leucine concentrations, traditional biomarkers, and calculated APACHE II and sequential organ failure assessment (SOFA) scores. Leucine levels were weakly correlated with albumin, prealbumin, and transferrin levels ( r = 0.30 , 0.12, and 0.15, p = 0.001 , 0.029, and 0.007, respectively). During follow-up, 116 (33.3%) patients died. Compared to patients with leucine levels between 109 and 174 μM, patients with leucine > 174 μ M or <109 μM had a lower cumulative survival rate. Death was also associated with age, higher APACHE II and SOFA scores, C-reactive protein, and longer stays in the ICU, but with lower albumin, prealbumin, and transferrin. Patients with leucine levels > 174 μ M had higher alanine aminotransferase levels, but no significant differences in other variables; patients with leucine levels < 109 μ M had higher APACHE II and SOFA scores, higher incidence of using inotropic agents, longer ICU and hospital stays, but lower albumin and transferrin levels. Multivariable analysis demonstrated that leucine > 174 μ M was an independent predictor of mortality, especially early mortality. However, among patients who stayed in ICU longer than two weeks, leucine < 109 μ M was an independent predictor of mortality. In addition, leucine < 109 μ M was associated with worse ventilator weaning profiles. These findings were similar in the validation cohort. Our study demonstrated a U-shape relationship between leucine levels and mortality rate in ICU.

Leucine Is More Readily Oxidized When Ingested as an Isolated Nutrient versus Incorporated in Its Whole-Food Matrix

Objectives The ingestion of free amino acids, or isolated sources of protein, results in faster postprandial release of dietary amino acids into circulation, which stimulates muscle protein synthesis rates. However, indirect evidence suggests that this rapid release of dietary amino acids after the ingestion of free amino acids is coupled with higher amino acid oxidation rates when compared to a whole-food source. Whole food protein results in a reduced peak amplitude and prolonged postprandial aminoacidemia. This study aimed to assess the effects of eating a whole food source of protein on the stimulation of whole-body leucine oxidation rates versus eating these same nutrients in isolated form in healthy young adults. Methods In a crossover design, 10 recreationally active adults (24 ± 4 y; 5 M, 5 F) performed an acute bout of resistance exercise followed by the ingestion of salmon (SAL) (20.5 g protein and 7.5 g fat) or its matched constituents as crystalline amino acids and fish oil (ISO). Participants received priming doses of NaH13CO2 and L-[1–13C]leucine before initiating a constant L-[1–13C]leucine infusion. Blood and breath samples were collected at rest and after resistance exercise at regular intervals for the measurement of whole-body leucine oxidation rates and plasma leucine profiles. Data were tested using linear fixed effects models with time and group as fixed factors with Bonferroni's post hoc test. Results Postprandial plasma leucine concentrations did not differ between the SAL and ISO conditions (P &gt; 0.05). Time to peak plasma leucine concentrations was faster in ISO (50 ± 27 min) vs. SAL (114 ± 64 min, P = 0.022) condition. Postprandial leucine oxidation rates were elevated from baseline at t = 30 min to t = 120 min in ISO and t = 60 min to t = 180 min in SAL (P &lt; 0.001), with no total differences between group (P = 0.129). Time to peak leucine oxidation occurred sooner in ISO (66 ± 22 min; 1.358 ± 0.699 nmol · kg−1 · min−1) when compared to the SAL condition (105 ± 20 min; 1.067 ± 0.3076 nmol · kg−1 · min−1; P = 0.002). Conclusions We show that the ingestion of a whole-food source of protein resulted in a delayed stimulation of leucine oxidation when compared to free amino acid ingestion, but a similar net increase in oxidation during the 5 h postprandial period in healthy young adults. Funding Sources USDA National Institute of Food and Agriculture Hatch project 1017928

Alcohol Acutely Antagonizes Refeeding-Induced Alterations in the Rag GTPase-Ragulator Complex in Skeletal Muscle

The Ragulator protein complex is critical for directing the Rag GTPase proteins and mTORC1 to the lysosome membrane mediating amino acid-stimulated protein synthesis. As there is a lack of evidence on alcohol’s effect on the Rag-Ragulator complex as a possible mechanism for the development of alcoholic skeletal muscle wasting, the aim of our study was to examine alterations in various protein–protein complexes in the Rag-Ragulator pathway produced acutely by feeding and how these are altered by alcohol under in vivo conditions. Mice (C57Bl/6; adult males) were fasted, and then provided rodent chow for 30 min (“refed”) or remained food-deprived (“fasted”). Mice subsequently received ethanol (3 g/kg ethanol) or saline intraperitoneally, and hindlimb muscles were collected 1 h thereafter for analysis. Refeeding-induced increases in myofibrillar and sarcoplasmic protein synthesis, and mTOR and S6K1 phosphorylation, were prevented by alcohol. This inhibition was not associated with a differential rise in the intracellular leucine concentration or plasma leucine or insulin levels. Alcohol increased the amount of the Sestrin1•GATOR2 complex in the fasted state and prevented the refeeding-induced decrease in Sestrin1•GATOR2 seen in control mice. Alcohol antagonized the increase in the RagA/C•Raptor complex formation seen in the refed state. Alcohol antagonized the increase in Raptor with immunoprecipitated LAMPTOR1 (part of the Ragulator complex) after refeeding and decreased the association of RagC with LAMPTOR1. Finally, alcohol increased the association of the V1 domain of v-ATPase with LAMPTOR1 and prevented the refeeding-induced decrease in v-ATPase V1 with LAMPTOR1. Overall, these data demonstrate that acute alcohol intake disrupts multiple protein–protein complexes within the Rag-Ragulator complex, which are associated with and consistent with the concomitant decline in nutrient-stimulated muscle protein synthesis under in vivo conditions.

Comparison of leucine-rich alpha-2-glycoprotein-1 (LRG-1) plasma levels between patients with and without appendicitis, a case–controlled study

Acute appendicitis (AA) is the first cause of emergency surgery. Leucine-Rich Alpha-2-Glycoprotein 1 (LRG1) has been shown to be a potential biomarker in cases of AA in children, but there are conflicting results for its use in adults. The objective of this study is to compare the median plasma values of LRG1 in patients with acute abdomen with and without appendicitis. This case–control study was conducted prospectively at the emergency room (ER) of a tertiary teaching hospital, between March 1st, 2011 and December 31st, 2012. Patients with recent abdominal pain, aged 18–70 years who attended at the ER were included in the study. Blood samples were drawn at the first presentation. Those who were submitted to surgery and had a pathology report of AA were considered as cases. Those without a need for surgery and treated for other conditions, e.g., pelvic inflammatory disease, were considered as controls. Follow-up in controls was made up to 30 days. LRG1 plasma median values were measured using an ELISA kit and compared between groups. A total of 28 participants, 14 cases with acute appendicitis and 14 controls, were included. The median (range) values of leucine-rich alpha-2-glycoprotein-1 level in the group with appendicitis and control group were 8.8 ng/ml (5.5–31) and 11 (4.6–108) ng/ml, respectively (Mann–Whitney test P = 0.26). Median plasma leucine-rich alpha-2-glycoprotein-1 levels were not useful in diagnosing Acute Appendicitis in patients with acute abdominal pain.

Plasma Amino Acid Response to Whey Protein Ingestion Following 28 Days of Probiotic (Bacillus subtilis DE111) Supplementation in Active Men and Women

We sought to determine if 28 days of probiotic supplementation influenced the plasma amino acid (AA) response to acute whey protein feeding. METHODS: Twenty-two recreationally active men (n = 11; 24.3 ± 3.2 yrs; 89.3 ± 7.2 kg) and women (n = 11; 23.0 ± 2.8 yrs; 70.2 ± 15.2 kg) participated in this double-blind, placebo-controlled, randomized study. Before (PRE) and after 28 days of supplementation (POST), participants reported to the lab following a 10-hr fast and provided a resting blood draw (0 min), then subsequently consumed 25 g of whey protein. Blood samples were collected at 15-min intervals for 2 h post-consumption (15–120 min) and later analyzed for plasma leucine, branched-chain AA (BCAA), essential AA (EAA), and total AA (TAA). Participants received a probiotic (PROB) consisting of 1 x10-9 colony forming units (CFU) Bacillus subtilis DE111 (n = 11) or a maltodextrin placebo (PL) (n = 11) for 28 days. Plasma AA response and area under the curve (AUC) values were analyzed via repeated measures analysis of variance. RESULTS: Our analysis indicated no significant (p < 0.05) differential responses for plasma leucine, BCAA, EAA, or TAA between PROB and PL from PRE to POST. AUC analysis revealed no group × time interaction for plasma leucine (p = 0.524), BCAA (p = 0.345), EAA (p = 0.512), and TAA (p = 0.712). CONCLUSION: These data indicate that 28 days of Bacillus subtilis DE111 does not affect plasma AA appearance following acute whey protein ingestion.

Very low ileal nitrogen and amino acid digestibility of zein compared to whey protein isolate in healthy volunteers

ABSTRACT Background Whey protein and zein are of nutritional interest due to their high leucine content, but little data are available on their amino acid (AA) ileal digestibility. Objective This study aimed to determine ileal digestibility of whey protein isolate (WPI) and zein in healthy volunteers by use of the naso-ileal intubation method, which allows continuous collection of postprandial ileal digesta. Methods Twenty-two healthy volunteers were intubated with a naso-ileal sampling device positioned at the terminal ileum level. They received a single meal of protein-free biscuits and a drink containing zein (n = 8), WPI (n = 7), or no protein (protein free, n = 7). Ileal effluents and plasma samples were collected over a 9-h postprandial period. Total nitrogen and AA contents were quantified in effluents. True ileal digestibility was calculated after correction for endogenous losses evaluated in the protein-free group. Results True ileal nitrogen digestibility of zein was markedly lower than WPI (60.2 ± 4.5% and 91.2 ± 2.6%, respectively, P = 0.0003). True ileal digestibility of AAs ranged from 87.4 ± 2.7% for threonine to 98.4 ± 1.0% for methionine in the WPI group, and from 59.3 ± 5.6% for methionine to 69.0 ± 5.8% for arginine in the zein group. The digestible indispensable AA (IAA) score was 1.03 (histidine) for WPI and close to 0 for zein, owing to its negligible lysine content. Plasma IAA concentration significantly increased after WPI intake (P = 0.0319), whereas no effect of zein on aminoacidemia was observed, including plasma leucine, despite its high leucine content. Conclusions Our findings provide data on ileal digestibility of WPI and zein AAs in healthy humans and, in contrast to WPI, zein is poorly digestible. This study was registered at clinicaltrials.gov as NCT03279211.

Novel Essential Amino Acid Supplements Following Resistance Exercise Induce Aminoacidemia and Enhance Anabolic Signaling Irrespective of Age: A Proof-of-Concept Trial

We investigated the effects of ingesting a leucine-enriched essential amino acid (EAA) gel alone or combined with resistance exercise (RE) versus RE alone (control) on plasma aminoacidemia and intramyocellular anabolic signaling in healthy younger (28 ± 4 years) and older (71 ± 3 years) adults. Blood samples were obtained throughout the three trials, while muscle biopsies were collected in the postabsorptive state and 2 h following RE, following the consumption of two 50 mL EAA gels (40% leucine, 15 g total EAA), and following RE with EAA (combination (COM)). Protein content and the phosphorylation status of key anabolic signaling proteins were determined via immunoblotting. Irrespective of age, during EAA and COM peak leucinemia (younger: 454 ± 32 µM and 537 ± 111 µM; older: 417 ± 99 µM and 553 ± 136 µM) occurred ~60–120 min post-ingestion (younger: 66 ± 6 min and 120 ± 60 min; older: 90 ± 13 min and 78 ± 12 min). In the pooled sample, the area under the curve for plasma leucine and the sum of branched-chain amino acids was significantly greater in EAA and COM compared with RE. For intramyocellular signaling, significant main effects were found for condition (mTOR (Ser2481), rpS6 (Ser235/236)) and age (S6K1 (Thr421/Ser424), 4E-BP1 (Thr37/46)) in age group analyses. The phosphorylation of rpS6 was of similar magnitude (~8-fold) in pooled and age group data 2 h following COM. Our findings suggest that a gel-based, leucine-enriched EAA supplement is associated with aminoacidemia and a muscle anabolic signaling response, thus representing an effective means of stimulating muscle protein anabolism in younger and older adults following EAA and COM.

P1521LRG-1 LEVEL PREDICTS 5-YEAR MORTALITY IN ESRD

Background and Aims Plasma Leucine-Rich alph-2-Glycoprotein 1(LRG1) is an new biomarker for inflammatory and angiogenetic diseases. whether levels of plasma LRG1 correlate with the co-morbidities of End stage renal disease (ESRD) patients is unknown. Method Plasma LRG-1 and high-sensitivity C-reactive protein were analyzed by ELISA in samples from 169 hemodialysis patients from the Immunity in ESRD study (iESRD study). Baseline co-morbidities were recorded through chart review of medical history. Results High level of LRG 1 showed high mortality in the ESRD. In multivariate-adjusted logistic regression models, higher LRG1 was significantly associated with 5 year mortality after adjusting for gender, hemoglobin, diabetes, hypertension, and level of C-reactive protein. Conclusion LRG1 is a possible poor prognosis marker in ESRD. Higher LRG-1 showed high prevalent CAD and PAOD in our study before. The role of LRG1 and the associated cardiovascular diseases should be analyzed the mechanism in this patient population.