Plasma Amino Acid Concentrations Research Articles

Plasma Amino Acid Appearance and Status of Appetite Following a Single Meal of Red Meat or a Plant-Based Meat Analog: A Randomized Crossover Clinical Trial

ABSTRACTBackgroundRed meat is a nutrient-dense food and a dietary staple. A new generation of plant-based meat analogs (PBMAs) have been designed to mimic the experience of eating meat, but there is limited evidence about their digestive efficacy and nutritional quality.ObjectivesWe compared the postprandial digestive response of a single meal containing meat commercially raised in New Zealand, including lamb, on-farm pasture-raised beef (Pasture), or grain-finished beef (Grain) with a PBMA (Beyond Burger; Beyond Meat) sold through consumer retail. The primary outcome was the appearance of amino acids in plasma. Secondary outcomes included glucose and insulin, appetite assessment, and anthropometry.MethodsThirty healthy men (20–34 y) participated in a double-blinded randomized crossover trial. Each consumed 1 of the 4 test meals on 4 occasions separated by a washout period of at least 1 wk, following an overnight fast. The meal was a burrito-style wrap containing meat or PBMAs, vegetables, salsa, and seasonings in a flour tortilla. The amount of Pasture, Grain, Lamb, or BB was 220 g raw (∼160 g cooked). Venous blood samples were collected over 4 h. Appetite and hunger status was scored with visual analog scales.ResultsPre-meal amino acid concentrations in plasma did not differ by group (P > 0.9), although several nonessential amino acids differed strongly according to participant BMI. Postprandial amino acids peaked at 2–3 h in all groups. The BB meal produced significantly lower plasma concentrations of total, essential, branched-chain, and non-proteogenic amino acids than the Lamb, Pasture, or Grain meals, based on AUC. There were no significant differences between meal groups in scores for hunger, fullness, or cravings.ConclusionsRed meat meals exhibited greater bioavailability of amino acids compared with the PBMA (BB). Pasture versus Grain origins of the beef had little influence on participants’ responses. This trial was registered at ClinicalTrials.gov as NCT04545398.

The importance of plasma amino acid profiling in the diagnosis of inborn errors of metabolism: analytical – prospective study

Introduction. Inborn errors of metabolism (IEM) make up a large group of disorders caused by an inherited defect of proteins that have enzymatic, carrier, receptor or structural roles. The cumulative prevalence of IEM in different populations is around 1:500 – 800 newborns, despite the fact that some of these disorders are extremely rare when taken individually. Early recognition and intervention are essential to avoiding disastrous consequences associated with IEM. The phenotype of IEM patients is very heterogeneous and only in combination with specialized metabolic test it can lead to a correct diagnosis. The aim of the study was defined as evaluation of importance of plasma amino acid profile in the diagnosis of IEM. Material and methods. Plasma amino acids quantification have been performed by high performance liquid chromatography on Shimadzu LC-20 with post column derivatization with OPA in 15 patients aged from 0 to 13 years old, selected through medical genetic counseling, based on inclusion and exclusion criteria. Inform consent has been signed by parents after receiving all necessary information regarding the study. Additionally, liquid chromatography-tandem mass spectrometry (LC-MS/MS) on dried blood spots and Nuclear Magnetic Resonance Spectroscopy (H1-NMR) on urine has been done as complementary tests. Results. The first line investigations showed acid-base imbalance (33,3%), hypoglycemia (46,6%), high lactate level (46,6%) and high ammonia level (20%). Plasma amino acid concentrations were abnormal in 4 patients (27%). Increased glycine (544 μmol/L, reference values 70,72 – 256,36 μmol/L), along with elevated glycine in cerebrospinal fluid (CSF) / plasma ratio (0,147, normal < 0.02) was detected in a patient with seizures, coma, and respiratory arrest indicating non-ketotic hyperglycinemia. High level of phenylalanine (Phe 1568µmol/L, reference values 26.52 – 221 µmol/L) has been identified in a patient suspected for Phenylketonuria after neonatal screening results (Phe > 3mg/dL). Also the ratio Phe / Tyr around 17 was specifically appreciated as for classical form of PKU. High alanine concentration (> 450 µmol/L) has been observed in two patients presenting severe metabolic acidosis and high lactate level, suggesting for a metabolic error with mitochondrial involvement. The results from extended newborn screening and NMR spectroscopy narrowed the spectrum of suspected diseases, facilitating the diagnosis. Molecular genetic tests are required for the confirmation of disease in all cases. Conclusions. Quantitative amino acids analysis is an important tool for the diagnosis of “intoxication type” of IEMs and nutritional monitoring of individuals with already established diagnosis.

Essential Amino Acid Regulation of Protein Turnover to Support Skeletal Muscle Health with Age

Skeletal muscle (SM) is vital for both long term health and quality of life. Recent research suggests an increase in catabolic signals with age triggers pathologic conditions, such as sarcopenia. Although results from in vitro studies model how essential amino acids (EAA) can regulate muscle protein synthesis (MPS), the relevance of these models to muscle protein breakdown (MPB), and the presence of physiological plasma amino acid concentrations (PAA) remain to be established. Therefore, the objective of this study was to determine the effects of EAA with (0.2, 1.0, and 3.0 x PAA) in a young (passages 2‐10) and aging (passages 16‐24) C2C12 murine muscle cell model. We hypothesized that increased levels of EAA will increase MPS in aging cells and suppress MPB via the mTORC1 pathway when compared to young cells. Myoblasts were seeded (1x105) into 6‐well plates and differentiated into myotubes when they reached 80% confluency. Myotubes were serum and AA starved for 24 hours before receiving one of the following treatments: control (CON), 0.2 x PAA, 1.0 x PAA, 3.0 x PAA with or without rapamycin (100 nm; RAP) for 1, 6, and 24 hours. All treatments were performed in triplicate and then each experiment was repeated three times, yielding nine wells per treatment. Proteins related to sensing of AA and protein synthesis and degradation were assessed using Western Blot. Rapamycin inhibited phosphorylation of p70 S6 kinase 1 (p70S6K1) and 4E binding protein 1 (4E‐BP1), downstream targets of mTORC1, in both CON and AA‐treated young and aged cells. Phosphorylation of 4EBP1 and p70S6K1 was significantly increased (p<0.05) in both young and aged cells following all PAA treatments. However, there was no significance after 24 hours of AA supplementation in aged cells. Particularly, after 6 hours of treatment all doses significantly increased (p<0.0001) phosphorylation of p70S6K1 in both young and aged cells. 0.2 x PAA and 3.0 x PAA elicited a significantly greater response in 4EBP1 phosphorylation in young cells compared to the CON after 6 hours of treatment, whereas a dose of 3.0 x PAA induced a similar response in aged cells. In conclusion, in a C2C12 myotube model, increasing EAA concentrations downregulates the expression of translation initiation factors in young and aging cells. Specifically, it takes a 3.0 x PAA to elicit a response in aging cells, whereas young cells respond to lower physiological concentrations of 0.2 x PAA and 1.0 x PAA. Therefore, it can be proposed increasing EAA may be effective for adjusting the rate of MPS and MPB via the mTORC1 pathway in both young and aging muscle cells.

Circulatory amino acid responses to milk consumption in dairy and lactose intolerant individuals

Background/objectivesSelf-reported digestive intolerance to dairy foods is common. As dairy can be an important source of dietary protein, this study aimed to identify whether milk protein digestion is compromised in individuals with digestive intolerance.Subjects/methodsAdult women (n = 40) were enroled in this double-blinded, randomised cross-over trial, with digestive symptoms characterised using a lactose challenge and self-reported digestive symptom questionnaire. Participants were classified as either lactose intolerant (LI, n = 10), non-lactose dairy intolerant (NLDI, n = 20) or dairy tolerant (DT, n = 10). In a randomised sequence, participants consumed three different kinds of milk (750 ml); conventional milk (CON), a2 Milk™ (A2M), and lactose-free conventional milk (LF-CON). Circulatory plasma amino acid (AA) concentrations were measured at baseline and every 30 min until 3 h post-ingestion.ResultsIn all participants across all milk types, plasma AA concentrations (AUC0-180) increased after milk ingestion with no significant differences in responses observed between milk types or participants (P > 0.05), with the exception of the suppressed lysine response in the DT group following A2M ingestion, relative to the other two groups and milk types (P < 0.05).ConclusionMilk protein digestion, as determined by circulatory AAs, is largely unaffected by dairy- and lactose- intolerances.

Amino Acid Metabolism and Protein Turnover in Lean and Obese Humans During Exercise-Effect of IL-6 Receptor Blockade.

Interleukin-6 (IL-6) is implicated in skeletal muscle wasting and in regulating skeletal muscle hypertrophy in the healthy state. This work aimed to determine the role of IL-6 in regulating systemic protein and amino acid metabolism during rest, exercise, and recovery in lean and obese humans. In a nonrandomized, single-blind design, 12 lean and 9 obese individuals were infused first with 0.9% saline (Saline), secondly with the IL-6 receptor antibody tocilizumab (Acute IL-6R ab), and 21 days later with saline while still under tocilizumab influence (Chronic IL-6R ab). Outcome measures were determined before, during, and after 90 minutes of exercise at 40% Wattmax by isotope dilution technique, using primed continuous infusion of L-[ring-D5]phenylalanine and L-[D2]tyrosine. Main outcomes measures included systemic protein turnover and plasma amino acid concentrations. We saw no effect of acute or chronic IL-6 receptor blockade on protein turnover. In lean individuals, chronic IL-6 receptor blockade increased plasma concentrations of total amino acids (rest Δ + 186 μmol/L; 95% CI, 40-332; recovery Δ + 201 μmol/L; 95% CI, 55-347) and essential amino acids (rest Δ + 43 μmol/L; 95% CI, 12-76; recovery Δ + 45 μmol/L; 95% CI, 13-77) independently of exercise but had no such effect in obese individuals (total amino acids rest Δ + 63 μmol/L; 95% CI, -170 to 295, recovery Δ - 23 μmol/L, 95% CI, -256 to 210; essential amino acids rest Δ + 26 μmol/L; 95% CI, -21 to 73, recovery Δ + 11 μmol/L; 95% CI, -36 to 58). IL-6 receptor blockade has no effect on protein turnover in fasting lean and obese humans during rest, exercise, and recovery. Chronic IL-6 receptor blockade increases total and essential amino acid concentrations only in lean individuals.

Neither Incretin or Amino Acid Responses, nor Casein Content, Account for the Equal Insulin Response Following Iso-Lactose Loads of Natural Human and Cow Milk in Healthy Young Adults.

Human milk contains <50% less protein (casein) than cow milk, but is equally effective in insulin secretion despite lower postingestion hyperaminoacidemia. Such potency of human milk might be modulated either by incretins (glucagon-like polypeptide-1,GLP-1); glucose-inhibitory-polypeptide, GIP), and/or by milk casein content. Healthy volunteers of both sexes were fed iso-lactose loads of two low-protein milks, i.e., human [Hum] (n = 8) and casein-deprived cow milk (Cow [↓Cas]) (n = 10), as well as loads of two high-protein milks, i.e., cow (n = 7), and casein-added human-milk (Hum [↑Cas]) (n = 7). Plasma glucose, insulin, C-peptide, incretins and amino acid concentrations were measured for 240′. All milks induced the same transient hyperglycemia. The early [20′–30′] insulin and C-peptide responses were comparable among all milk types apart from the low-protein (Cow [↓Cas]) milk, where they were reduced by <50% (p < 0.05 vs. others). When comparing the two high-protein milks, GLP-1 and GIP [5’–20’] responses with the (Hum [↑Cas]) milk were lower (by ≈2–3 fold, p < 0.007 and p < 0.03 respectively) than those with cow milk, whereas incretin secretion was substantially similar. Plasma amino acid increments largely reflected the milk protein content. Thus, neither casein milk content, nor incretin or amino acid concentrations, can account for the specific potency of human milk on insulin secretion, which remains as yet unresolved.

Cheese Ingestion Increases Muscle Protein Synthesis Rates Both at Rest and During Recovery from Exercise in Healthy, Young Males: A Randomized Parallel-Group Trial

ABSTRACTBackgroundProtein ingestion increases muscle protein synthesis rates. The food matrix in which protein is provided can strongly modulate the postprandial muscle protein synthetic response. So far, the muscle protein synthetic response to the ingestion of whole foods remains largely unexplored.ObjectivesTo compare the impact of ingesting 30 g protein provided as milk protein or cheese on postprandial plasma amino acid concentrations and muscle protein synthesis rates at rest and during recovery from exercise in vivo in young males.MethodsIn this randomized, parallel-group intervention trial, 20 healthy males aged 18–35 y ingested 30 g protein provided as cheese or milk protein concentrate following a single-legged resistance-type exercise session consisting of 12 sets of leg press and leg extension exercises. Primed, continuous intravenous L-[ring-13C6]-phenylalanine infusions were combined with the collection of blood and muscle tissue samples to assess postabsorptive and 4-h postprandial muscle protein synthesis rates at rest and during recovery from exercise. Data were analyzed using repeated measures Time × Group (× Leg) ANOVA.ResultsPlasma total amino acid concentrations increased after protein ingestion (Time: P < 0.001), with 38% higher peak concentrations following milk protein than cheese ingestion (Time × Group: P < 0.001). Muscle protein synthesis rates increased following both cheese and milk protein ingestion from 0.037 ± 0.014 to 0.055 ± 0.018%·h–1 and 0.034 ± 0.008 to 0.056 ± 0.010%·h–1 at rest and even more following exercise from 0.031 ± 0.010 to 0.067 ± 0.013%·h–1 and 0.030 ± 0.008 to 0.063 ± 0.010%·h–1, respectively (Time: all P < 0.05; Time × Leg: P = 0.002), with no differences between cheese and milk protein ingestion (Time × Group: both P > 0.05).ConclusionCheese ingestion increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial muscle protein synthetic response to the ingestion of cheese or milk protein does not differ when 30 g protein is ingested at rest or during recovery from exercise in healthy, young males.

Oxidative stress biomarkers and free amino acid concentrations in the blood plasma of moderately exercised horses indicate adaptive response to prolonged exercise training.

Oxidative stress caused by routine physical stressors may negatively impact the performance of equine athletes; thus, the present study identifies oxidative biomarkers in the blood plasma of exercising horses. Stock-type horses were subject to a standardized moderate-intensity exercise protocol 3 times per week for 8wk. Exercise protocol followed NRC guidelines consisting of 30% walk, 55% trot, and 15% canter, with a target heart rate (HR) of 90 BPM. Blood plasma was collected in wk 1, 2, 7, and 8 immediately before and 0, 30, 60, and 90min after exercise and analyzed for total antioxidant capacity (TAC), thiobarbituric acid reactive substance (TBARS), glutathione peroxidase activity (GPx), and superoxide dismutase activity (SOD). Data were analyzed as repeated measures with wk, d, time, and their interactions as fixed effects. The TAC on day 2 (0.40mM Trolox) was 7.5% greater than on day 3 (P = 0.013). There were wk × d × time interactions for SOD, TBARS, and GPx (P < 0.001). The TBARS remained at pre-exercise baseline (d-1 wk-1; 2.7 µM malondialdehyde) for most collection times within weeks 1, 7, and 8 (P ≥ 0.058); however, TBARS increased by 0.24 to 0.41 µM on day 2 of week 2 post-exercise (P < 0.001) and remained similarly elevated on day 3 pre- and immediately post-exercise (P < 0.001). The GPx similarly remained at baseline (172.6 µM/min; P ≥ 0.621) but increased by 48.18 to 83.4 µM/min at most collection times on days 1 and 2 of week 2 (P ≤ 0.023). The SOD remained at baseline (167.2 U/ mL; P ≥ 0.055) until increasing by 11.28 to 15.61 U/mL at 30min post-exercise on day 1, week 1 and at most collection times on day 3, week 8 (P ≤ 0.043). Amino acids with antioxidant properties such as Met, Tyr, and Trp drastically decreased from weeks 2 to 8 (P < 0.001). Met and Tyr also decreased from -60 to 90min (P < 0.047), whereas there was no time effect on Trp concentration (P = 0.841). The current study indicates the time-dependent nature of oxidative stress concerning persistent stressors such as exercise.

The effects of maternal supplementation of rumen-protected lysine during the close-up dry period on newborn metabolism and growth in Holstein calves.

This study aimed to evaluate the effects of rumen-protected lysine (RPL) supplementation during the close-up period on blood metabolites and calf growth. Forty multiparous Holstein dams were selected based on parity, body condition score, and expected calving date, and randomly assigned to a group: with RPL (n = 22) or without (control [CON], n = 18). RPL dams were supplied daily with 80 g of RPL from Day 21 before the expected calving date to parturition. Blood samples were obtained from the dams before the start of supplementation, 1 week before calving, and immediately after calving, and from calves immediately after birth and weekly until 8 weeks of age. Body weight measurements were performed immediately after birth in all calves and at weekly intervals until 8 weeks of age in female calves. No significant difference was observed in serum metabolite levels and plasma amino acid concentrations between the RPL and CON dams before supplementation, whereas plasma lysine concentrations tended to be higher in RPL dams immediately after calving (p = 0.07). Serum total protein levels (p < 0.05) were higher, whereas plasma total amino acid, total essential amino acid, total non-essential amino acid, and other amino acid concentrations were lower in the calves of RPL dams than those of CON dams (p < 0.05). There were no significant differences in calf birth weight between the two groups, although female calves of RPL dams (n = 7) had higher serum total protein (p < 0.05) and tended to have greater body weight (p = 0.09) from 1 to 8 weeks of age than those of CON dams (n = 11). Overall, RPL supplementation during the close-up period may increase placenta-mediated amino acid transfer to the foetus and enhance protein synthesis in the calf, leading to improved weight gain during the suckling period.

An evaluation of elevated branched-chain amino acid inclusions on the performance of broiler chickens offered reduced-crude protein, wheat-based diets from 7 to 28 days post-hatch

The physiological functions of essential branched chain amino acids (BCAA) are important in broiler nutrition, but antagonistic BCAA interactions may become evident. Given the increased implementation of reduced-crude protein (CP) diets, this study aimed to investigate whether elevated leucine inclusions in reduced-CP diets would advantage broiler growth performance, provided concomitant elevations in isoleucine and valine were employed. A total of 378 off-sex male Ross 308 broilers were allocated to 9 dietary treatments, each with 7 replicate cages and 6 birds in each. All diets were wheat-based with 190 g/kg CP. The dietary treatments comprised 3 leucine inclusions (12.71, 15.02, 17.33 g/kg) and 3 isoleucine plus valine inclusions (17.21, 20.32, 23.45 g/kg) in a 3 × 3 factorial array. The assessed parameters included growth performance, relative abdominal fat-pad weights, nutrient utilisation, apparent jejunal and ileal digestibility coefficients and disappearance rates of starch, protein (N), amino acids and free amino acid concentrations in systemic plasma. Elevated BCAA inclusions did not enhance growth performance; indeed, elevating isoleucine plus valine from 17.21 to 20.32 g/kg in the 15.02 g/kg leucine diet significantly compromised weight gain by 6.82% (1325 versus 1422 g/bird). However, elevating isoleucine plus valine inclusions from 17.21 to 20.32 g/kg decreased relative fat-pad weights by 8.49% (9.05 versus 9.89 g/kg; P = 0.046). Elevating leucine levels significantly depressed energy utilisation, AME and AMEn, by 0.39 MJ in both instances. Dietary enrichment with leucine had diverse impacts on amino acid digestibility coefficients coupled with free amino acid plasma concentrations. Increasing dietary leucine concentrations improved ileal digestibility of leucine by 4.74% (0.906 versus 0.865) but also significantly increased ileal digestibility coefficients of another 10 amino acids by an average of 3.37% ranging from 1.60% (methionine) to 4.96% (threonine). Overall, elevations of BCAA in wheat-based, reduced-CP diets did not advantage broiler growth performance. The likelihood is that several factors are responsible for this lack of response and consideration is given to these possibilities in this paper.

Metabolic changes induced by dapagliflozin, an SGLT2 inhibitor, in Japanese patients with type 2 diabetes treated by oral anti-diabetic agents: A randomized, clinical trial

AimWe aimed to determine whether SGLT2 inhibitor dapagliflozin treatment affects body composition and amino acid (AA) metabolism. MethodsFifty-two overweight patients treated by oral antidiabetic agents were randomly assigned to dapagliflozin (Dapa) or a standard treatment (Con) and followed for 24 weeks. The primary outcome was the change in body mass (BM) between baseline and week 24. Body composition, intrahepatic triglyceride (IHTG) content, and plasma AA concentrations were examined as secondary outcomes. ResultsThe change in BM was significantly larger in the Dapa than in the Con group, with a difference in the mean change of −1.72 kg (95 %CI: −2.85, −0.59; P = 0.004) between the groups. Total fat mass was reduced by dapagliflozin treatment, but fat-free mass was maintained. IHTG content was significantly reduced in the Dapa than in the Con (P = 0.033). Changes in AAs showed small differences between the groups, but only serine concentrations were significantly reduced in the Dapa. Intra-group analysis showed that positive associations were observed between changes in branched chain AA concentrations and body composition only in the Dapa. ConclusionsDapagliflozin treatment causes a reduction in BM mainly by reducing fat mass. AA metabolism shows subtle changes with dapagliflozin treatment.

Effects of increased doses of lysine in a rumen-protected form on plasma amino acid concentration and lactational performance of dairy cows fed a lysine-deficient diet

The objective of these studies was to determine the effects of feeding a novel rumen-protected Lys (RP-Lys) product on plasma AA, lactational performance, and Lys bioavailability. To evaluate RP-Lys on lactation performance a corn-based diet (42.5% of corn silage and 21.9% of corn and corn by-products, on DM basis) was formulated to be Lys deficient but adequate in Met, energy, and metabolizable protein. Thirty-six lactating Holstein cows were fed either a Lys-deficient control diet (CON) with no added RP-Lys, or diets containing 0.3% of RP-Lys (0.3RP-Lys) or 0.6% of RP-Lys (0.6RP-Lys) for 8 wk. There were no effects on dry matter intake (mean ± SD; 26.1 ± 0.58 kg/d), milk yield (37.9 ± 0.72 kg/d), or milk composition to the RP-Lys supplementation. No effect was observed on plasma AA concentrations except for His. Plasma His was linearly reduced by Lys feeding (42.6, 41.2, 30.0 ± 4.09 μM, for CON, 0.3RP-Lys, and 0.6RP-Lys, respectively). Calculated efficiency of Lys utilization decreased linearly with RP-Lys supplementation. In the companion study, 3 rumen-cannulated lactating dairy cows were used in a 3 × 3 Latin square design to assess the bioavailability of the RP-Lys. Free Lys (HCl-Lys), RP-Lys, and water were administered separately by postruminal bolus dosing. The Lys bioavailability was assessed by the ratio of area under the curve of Lys plasma concentration for RP-Lys compared with HCl-Lys and discounted for the area under the curve for water bolus dose. The estimated bioavailability of the RP-Lys was 24.4% ± 4.61. In summary, increased supplemental doses of Lys had no effect on Lys plasma concentration and lactational performance when fed to dairy cows on a corn-based diet, although altered Lys as % of essential AA was observed. However, the lack of effects should be considered in light of the lower-than-expected bioavailability of the RP-Lys.

Milk performance and oxidative status responses to rumen protected methionine supplementation in genotyped α-S1 casein lactating dairy goats fed two levels of metabolizable protein diets

In dairy goats, responses to rumen-protected Methionine (RPM) supplementation on milk performance and milk protein synthesis were inconsistent. The objective of the study was to evaluate the effects of supplemental RPM in diets differing in CP content on milk performance, milk composition, plasma concentration of amino-acids (AA) and parameters of oxidative status in goats genotyped for their genetic variant for alpha-S1 casein (CNS1). Sixteen goats (Body weight = 66.6 ± 8.5 kg, days in milk = 89 ± 5) were grouped into 2 blocks (High vs Low) according to their secretion of CNS1 in milk, and within each CNS1 block, goats were selected to make blocks comparable for milk yield, milk protein content, body weight and days in milk. Goats within CNS1 blocks were allotted to 2 periods cross-over (4 wks for each period with one washout week) nested in 2 × 2 factorial design with dietary CP (LP vs HP, 14 vs 16 % CP in TMR fed ad libitum) and RPM supplementation (CTL vs RPM, 0 vs 4 g/d). Dry matter intake and milk yield were individually recorded daily, whereas milk samples for milk composition determination, and blood samples were obtained individually twice weekly, and once weekly, respectively. Blood was sampled for glucose, NEFA, BHB, urea, insulin, total or oxidized glutathion, superoxide dismutase, catalase, malondialdehyde, and protein carbonyl. At the end of each period, blood was sampled during two consecutive wks to determine plasma AA profile. Goats fed HP diet had higher CP, PDIE, and LysDi (lysine digestible in intestine) intake than those fed LP diet, whereas goats supplemented with RPM had higher MetDi (methionine digestible in intestine) intake (P < 0.001) than those fed the CTL diet. Goats fed HP diet had similar milk performance, milk composition and yields, and similar feed, energy and PDI efficiencies, but higher milk urea concentration than those fed LP diet. Goats supplemented with RPM had higher milk yield only when fed the LP diet (RPM x dietary CP: P < 0.02). Compared to goats fed CTL diet, those supplemented with RPM had higher milk protein content, but this was observed only in those fed HP diet (RPM x dietary CP: P < 0.008), especially for Low CNS1 goats (RPM x CNS1: P < 0.05; RPM x dietary CP x CNS1: P < 0.11). Efficiencies of PDI, feed and energy were not altered by RPM supplementation, but CNS1 x dietary CP x RPM interaction was significant for these efficiencies. Goats supplemented with RPM tended to have higher plasma MDA (P < 0.07) and total glutathione concentrations (P < 0.09). In conclusion, increasing dietary CP failed to improve DMI, milk performance, milk protein content and protein yield, which suggest that Net Energy for lactation was a limiting factor of our experimental diets. With RPM supplementation, increase in milk production in the low CP group, and increase in milk protein content in the high CP group suggests that changes in metabolic partition of nutrients between milk secretion vs milk protein synthesis occurs according to the level of limitation of methionine in diet, which may affect the methionine requirement for goat milk production.

A phase I dose-escalation study of eryaspase in combination with modified FOLFIRINOX in locally advanced and metastatic pancreatic ductal adenocarcinoma: Interim update.

581 Background: The prognosis for advanced metastatic pancreatic adenocarcinoma remains dismal with median survival of 12-15 months in most recent trials, highlighting the urgent need for novel therapeutic agents. mFOLFIRINOX remains the standard of care for the first line treatment of advanced disease, with historical objective response rate (ORR) of ̃31%. Eryaspase, L-asparaginase (ASPNase) encapsulated in red blood cells (RBCs), is an investigational product under development. Following infusion, asparagine is actively transported in RBCs where it is hydrolyzed by encapsulated ASPNase. The reduction in plasma concentration of this essential amino acid leads to cancer cell death. A second line pivotal randomized phase III trial (Trybeca-1), which compares chemotherapy (Gemcitabine + Nab-Paclitaxel or 5-Fluorouracil + Irinotecan) with or without Eryaspase, has completed enrollment with results pending (NCT03665441). Methods: Patients with locally advanced or metastatic biopsy-proven pancreatic adenocarcinoma were treated with the combination of mFOLFIRINOX plus Eryaspase. The design was a standard 3 +3 dose escalation. mFOLFIRINOX was given as 5-Fluorouracil 2400 mg/m2 over 46 hours, Oxaliplatin 85 mg/m2, Irinotecan 150 mg/m2 plus Eryaspase 75 units/kg at dose level 0 or 100 units/kg at dose level 1. Key eligibility criteria include performance status of 0 or 1, locally advanced or metastatic disease, and adequate organ function. The primary objectives were to determine the maximum tolerated dose (MTD) and to determine the safety of this combination. Results: To date, nine patients have been enrolled with a mean age of 70. Four patients had locally advanced disease and five had metastatic disease. Three patients were enrolled at dose level 0 and six at dose level 1, with no dose limiting toxicities (DLT). Eight patients have had imaging to evaluate response: the ORR was 50% with four partial responses (PRs); 50% (N = 4) had stable disease (SD); disease control rate (PR + SD) was 100%. There were no grade 4 adverse events (AEs). The most common grade 3 AEs were hypokalemia (33%), fatigue (11%), and hypotension (11%); but they were beyond the DLT period of 28 days. The most common grade 1/2 AEs were neuropathy (78%), elevated liver enzymes (78%), nausea (78%), anemia (66%), fatigue (66%), diarrhea (66%), and mucositis (44%). Conclusions: The novel combination of mFOLFIRINOX plus Eryaspase was well tolerated with no DLT and has encouraging signs of clinical activity. The MTD has been declared with 5-FU 2400 mg/2, Oxaliplatin 85 mg/2, Irinotecan 150 mg/m2, and Eryaspase 100 units/kg. We plan to expand enrollment to further look at efficacy and are in the process of designing a larger randomized study in the first line setting pending results from the Trybeca-1 trial. Clinical trial information: NCT04292743.

Amino acid intake and plasma concentrations and their interplay with gut microbiota in vegans and omnivores in Germany

PurposeIt has been estimated that most vegans meet the total protein requirements, but whether this is also true for individual essential amino acids (AAs) is unclear. Furthermore, a shift in protein intake is suggested to alter microbiota composition, but this association is unknown in terms of veganism or individual AAs. This cross-sectional study compared vegans and omnivores regarding dietary intake and plasma concentration of AAs. The prevalence of insufficient intake of essential AAs among vegans was determined using estimated average requirements (EAR) of WHO. Moreover, correlations between AAs intake and gut microbiota were investigated.MethodsData of 36 vegans and 36 omnivores (30–60 years) were analysed. AA intake, AA plasma concentrations and gut microbiota were ascertained by three-day weighed food protocols, gas/liquid chromatography-tandem mass spectrometry and 16S rRNA sequencing, respectively.ResultsAt almost the same energy intake, the intake of 9 AAs in vegans was significantly lower than in omnivores, with median differences of − 27.0% to − 51.9%. However, only one female vegan showed total protein and lysine intake below the EAR. Vegans showed lower lysine (− 25.0%), but higher glycine (+ 25.4%) and glutamate (+ 13.1%) plasma concentrations than omnivores. Correlation patterns between AA intake and bacterial microbiota differed between vegans and omnivores. In vegans 19 species and in omnivores 5 species showed correlations with AA intake.ConclusionVegans consumed apparently sufficient but lower AAs than omnivores. In addition, the different AAs intake seems to influence the microbiota composition. The use of short-term dietary data without considering usual intake limits these findings.

Plasma Amino Acids May Improve Prediction Accuracy of Cerebral Vasospasm after Aneurysmal Subarachnoid Haemorrhage.

Aneurysmal subarachnoid haemorrhages (aSAH) account for 5% of strokes and continues to place a great burden on patients and their families. Cerebral vasospasm (CVS) is one of the main causes of death after aSAH, and is usually diagnosed between day 3 and 14 after bleeding. Its pathogenesis remains poorly understood. To verify whether plasma concentration of amino acids have prognostic value in predicting CVS, we analysed data from 35 patients after aSAH (median age 55 years, IQR 39–62; 20 females, 57.1%), and 37 healthy volunteers (median age 50 years, IQR 38–56; 19 females, 51.4%). Fasting peripheral blood samples were collected on postoperative day one and seven. High performance liquid chromatography-mass spectrometry (HPLC-MS) analysis was performed. The results showed that plasma from patients after aSAH featured a distinctive amino acids concentration which was presented in both principal component analysis and direct comparison. No significant differences were noted between postoperative day one and seven. A total of 18 patients from the study group (51.4%) developed CVS. Hydroxyproline (AUC = 0.7042, 95%CI 0.5259–0.8826, p = 0.0248) and phenylalanine (AUC = 0.6944, 95%CI 0.5119–0.877, p = 0.0368) presented significant CVS prediction potential. Combining the Hunt-Hess Scale and plasma levels of hydroxyproline and phenylalanine provided the model with the best predictive performance and the lowest leave-one-out cross-validation of performance error. Our results suggest that plasma amino acids may improve sensitivity and specificity of Hunt-Hess scale in predicting CVS.

The comparison of nucleotide metabolites and amino acids patterns in patients with eating disorders, with and without symptoms of depression

Purines, pyrimidines, and amino acid level have gained attention recently as potential determinants of mental disorders. However, eating disorders patients (ED) have not been yet appropriately studied, especially subjects with coexisting mood disorders. This paper examines the serum level of nucleotide catabolites and plasma amino acids in eating disorders with hyperphagia, with and without Major Depressive Disorder (MDD). Samples were taken from adult persons suffering from eating disorders (two forms: simple obesity and binge eating disorder) with MDD (n = 20) and without (n = 17). Serum nucleotides and plasma amino acids concentrations were analyzed with high-performance liquid chromatography-mass spectrometry. The nucleotides metabolite in MDD patients had a significantly (p < 0.05) lower uridine. Among MDD patients with ED significantly (p < 0.05) higher levels of asparagine, glutamine, proline, and arginine were found as compared to the control group. This study demonstrated differences in nucleotide metabolite and amino acid pattern in depression patients with eating disorders. This may be relevant to the mechanisms and may help identify biomarkers.

Effect of ensiled total mixed rations containing sake lees on digestion, nitrogen use, and plasma metabolite concentrations in sheep.

Sake lees are a byproduct of Japanese rice wine and used as ruminant feed with high protein and ethanol contents. This study aimed to explore the effects of ensiled total mixed ration (TMR) containing sake lees on rumen fermentation, digestion, nitrogen (N) use, and plasma metabolites in sheep. Four mature wethers were assigned to a 4 × 4 Latin square design with a factorial arrangement of ensiling treatment (non-ensiled or ensiled TMR) and types of sake lees (traditional or liquefied). Although dietary ethanol consumption was higher in sheep fed ensiled TMR, ruminal and plasma concentrations of methanol and ethanol increased after feeding in all dietary treatments, which was accompanied by the increased plasma concentrations of formate. The intake and digestion of dry matter and N were lower in sheep fed ensiled TMR than in those fed non-ensiled TMR. The plasma concentrations of most amino acids decreased in sheep fed ensiled TMR. Although plasma methionine, serine, and glycine concentrations were not altered by diet, homocysteine concentration was the highest in sheep fed ensiled TMR containing traditional sake lees. The negative impacts of ensiling treatment on N digestion and amino acid utilization should be considered for formulating ensiled TMR containing sake lees.

Eff ects of Supplementation with Rumen-Protected Methionine on Milk Performance, Plasma Biochemical Indices and Amino Acid Concentration in Dairy Goats Subject to Heat Stress

Eff ects of Supplementation with Rumen-Protected Methionine on Milk Performance, Plasma Biochemical Indices and Amino Acid Concentration in Dairy Goats Subject to Heat Stress

Amino Acid Homeostasis in Mammalian Cells with a Focus on Amino Acid Transport

Amino acid homeostasis is maintained by import, export, oxidation, and synthesis of nonessential amino acids, and by the synthesis and breakdown of protein. These processes work in conjunction with regulatory elements that sense amino acids or their metabolites. During and after nutrient intake, amino acid homeostasis is dominated by autoregulatory processes such as transport and oxidation of excess amino acids. Amino acid deprivation triggers processes such as autophagy and the execution of broader transcriptional programs to maintain plasma amino acid concentrations. Amino acid transport plays a crucial role in the absorption of amino acids in the intestine, the distribution of amino acids across cells and organs, the recycling of amino acids in the kidney, and the recycling of amino acids after protein breakdown.