Plasma Amino Acid Concentrations Research Articles

Low feed intake at weaning reduces intestinal glutathione levels and promotes cysteine oxidation to taurine in pigs

Abstract Weaning stress in pigs is associated with low feed intake and poor nutrient utilization. Cysteine is a sulfur amino acid with key roles in pig production, but how cysteine metabolism and requirements are affected by weaning stress should be better defined. The objective of this study was to determine the collective impact of weaning and feed restriction on tissue cysteine metabolism. Pigs were weaned at 21-d age without access to feed (W; 6.90 ± 0.81 kg; n = 9; reflecting acute nutritional stress) or were not weaned and remained with the sow (NW; 6.81 ± 0.65 kg; n = 8). At euthanasia (23-d age), blood, bile, and liver, jejunum, and ileum tissues were collected. Plasma, bile, and tissue amino acid and amino thiol concentrations were analyzed by HPLC. Activity of glutamate cysteine ligase (GCL) and glutathione synthetase (GSS), enzymes needed for glutathione (GSH) production, and cysteine dioxygenase 1 (CDO1) were determined with activity assays followed by HPLC analysis of reaction products. Plasma (271 versus 192 ± 19 µmol/L; P < 0.001) and liver (417 versus 298 ± 33 nmol/g; P < 0.05) Cys concentrations were increased in W compared to NW pigs. Despite greater plasma Cys, jejunum and ileum Cys content were not affected by weaning (P > 0.10), whereas γ-glutamylcysteine (γ-GlyCys), the immediate precursor of GSH, declined in both jejunum (14.3 versus 9.7 ± 1.4 nmol/g; P < 0.01) and ileum (11.2 versus 6.4 ± 0.8 nmol/g; P < 0.001) in W pigs. Glutathione content was lower in the jejunum (1379 versus 1720 ± 70 nmol/g; P < 0.05) and ileum (1497 versus 1740 ± 74 nmol/g; P < 0.05) in W pigs. In the jejunum, GCL activity tended to be greater (0.56 versus 0.39 ± 0.07 nmol γ-GluCys • mg-1 • min-1; P < 0.10), whereas GSS activity tended to be lower (1.11 versus 1.38 ± 0.10 nmol GSH • mg-1 • min-1; P < 0.10) in W compared to NW pigs. In the ileum, the activities of GCL and GSS were not affected by weaning (P > 0.10). Although liver CDO1 activity was not different between groups (P < 0.10), liver taurine was greater in W compared to NW pigs (5115 versus 2336 ± 912 nmol/g; P = 0.001). Bile concentrations of Cys (1203 versus 279 ± 103 µmol/L; P < 0.001) and cysteinylglycine (203 versus 117 ± 33 µmol/L; P < 0.10), the direct product of GSH degradation, were greater in W compared to NW pigs. Collectively, these results suggest that systemic Cys is not effectively utilized for gut GSH production in newly weaned pigs and is instead oxidized to taurine and eliminated in bile.

Nutritional quality of proteins from two beef co-products as determined in the growing pig.

The increasing demand for food and especially proteins leads to the search for alternative protein sources. Meat co-products, which are available but little used in human food, provide a potential solution to this challenge. The present study aimed to evaluate the nutritional quality of two beef protein ingredients (greasy greaves recovered proteins (GGRP) and water recovered proteins (WRP)), both co-products of the fat rendering process. Their true ileal digestibility (TID), digestible indispensable amino acid score (DIAAS) and kinetics of plasma amino acids (AA) were measured in ten growing pigs, each fed the two co-products and a protein-free diet. Titanium dioxide was used as an indigestible marker. Digesta samples were collected for 9 h after meal ingestion, and blood samples were collected at ten time points during the same period. Total nitrogen (N) and AA contents were determined. Data were statistically analysed using linear mixed models. The TID of total N was not different between WRP and GGRP (81-84 %, P > 0·05). The first-limiting AA was Trp for both ingredients, with a DIAAS much higher for GGRP than for WRP (74 and 10 % for adults, respectively; P < 0·001). Postprandial plasma AA concentration peaked earlier for WRP (3 h) than for GGRP (5 h). Plasma concentrations of total and essential AA were higher (P < 0·001) with GGRP diet than WRP diet. Overall, GGRP has a nutritional quality suitable to meet the needs of adults for AA, while WRP needs to be supplemented with other protein sources to fulfil the dietary requirements.

Beneficial Role of Heat-Treated Lactobacillus sakei HS-1 on Growth Performance, Nutritional Status and Gut Microbiota in Weaned Piglets.

In the swine industry, there is a strong need to replace an antibiotic growth promoter (AGP) used as feed additives in weaned piglets to enhance nutrient utilization in their diets and improve growth performance. Lactobacillus sakei HS-1 strain is a microbial preparation isolated from pickles. The study aim is to investigate the effectiveness of heat-treated L. sakei HS-1 strain (HT-LS) as a growth promoter in weaned piglets compared to colistin (CS), a widely used AGP. Eighteen crossbred weaned piglets (Landrace × Yorkshire × Duroc) of 21 days (average body weight [BW]: 7.06 ± 0.59 kg) were divided into three groups: fed the control diet (CT group), fed a diet supplemented with 30 ppm colistin sulphate (CS group), fed a diet supplemented with HT-LS at a concentration of 2.0 × 105 cells/g (LS group) until 49 days. The results indicated that LS group exhibited significantly higher average daily gain (p < 0.05) and higher BW (p < 0.1) compared with CT group, even higher than CS group. CS group showed higher growth performance compared to CT group but the differences were not statistically significant. In addition, LS group had higher (p < 0.05) or tended to higher (p < 0.1) concentrations of several plasma amino acids than the other two groups at 35 and 49 days. Faecal acetate concentration was higher (p < 0.1) in LS group than in CT group at 35 days. Blood immunoglobulin G concentration in LS group was significantly lower (p < 0.05) than in CT group at 35 and 49 days, and blood immunoglobulin A tended to be lower (p < 0.1) at 35 days than in CT group. LS group showed an increased abundance of g_Prevotella 7, g_Streptococcus and g_Lactobacillus (linear discriminant analysis [LDA] score ≥ 2.0). Predictive metagenomic analysis revealed an enrichment of the mixed acid fermentation pathway (LDA score ≥ 2.0). Furthermore, several gut microbes exhibited correlations with plasma amino acids (p < 0.01) and short-chain fatty acids in faeces (p < 0.01). These findings demonstrate that HT-LS improves the growth performance of weaned piglets by enhancing the efficient utilization of nutrients through gut microbiota modification.

Plasma amino acid concentrations in humans after nutralys® S85 PLUS PEA protein versus whey protein intake: Effect on protein anabolism in C2C12 myotubes.

Plasma amino acid concentrations in humans after nutralys® S85 PLUS PEA protein versus whey protein intake: Effect on protein anabolism in C2C12 myotubes.

Dietary early addition enzyme-treated soybean improves amino acid absorption and protein digestibility by promoting digestive enzyme activity in broilers

Early nutritional regulation has become a research hotspot. The present study was undertaken to assess dietary early addition enzyme-treated soybean meal (ESBM) on nutrients digestibility, amino acid absorption, and intestinal development of broilers. Four hundred and fifty 1-day-old broilers were divided into three groups with 10 replicates of 15 broilers and fed with a basic diet, 2.5 or 5% ESBM during 1-10 days. Then all groups were fed the same basic diets until 42 d. The obtained results indicated that supplementation of ESBM in early stage resulted in heavier BW and a better feed conversion ratio during the experimental periods compared with the control group. Supplementing the broiler’s diet with 5% ESBM led to enhance digestibility of dry matter, crude protein and decrease abdominal fat yield (P < 0.05). Meanwhile, 5% ESBM in the early diet increased villus height (P < 0.05, d 21) and reduced the crypt depth in jejunum and ileum (P < 0.05, d 42). Dietary 5% ESBM supplementation improved enzyme activity and upregulated nutrient transporters expression in jejunum, increased plasma amino acid (AA) concentrations (P < 0.05, d 10). In conclusion, our data demonstrated that supplementation ESBM promote intestinal development, upregulate AAs and peptide transporters gene expression for physiological absorption of AAs, and improve protein digestibility caused by intestinal enzyme activity, thereby improving growth performance.

Changes in Plasma Concentration of Free Proteinogenic and Non-Proteinogenic Amino Acids in High-Performance Sprinters over a 6-Month Training Cycle.

Background/Objectives: Free amino acids substantially contribute to energy metabolism. Also, their profile may identify (over)training status and effectiveness. The long-term effects of speed-power training on plasma free amino acid (PFAA) profiles are not known. We aimed to observe variations in PFAA levels in high-performance sprinters in a six-month training cycle. Methods: Ten male athletes (24.6 ± 3.3 years) were examined during four training phases: transition (1 month), general preparation (2 months), specific preparation (1 month), and pre-competition/competition (2 months). Venous blood was collected at rest, after exhaustive exercise, and recovery. Forty-two PFAAs were analyzed by the LC-ESI-MS/MS method. Results: Significant decreases in resting concentrations were observed between the transition and competition phases for glutamine (762 ± 117 vs. 623 ± 53 μmol∙L-1; p < 0.001, η2 = 0.47) and histidine (89 ± 15 vs. 75 ± 10 μmol∙L-1; p = 0.010, η2 = 0.27), whereas β-alanine (30 ± 7 vs. 41 ± 9 μmol∙L-1; p = 0.024, η2 = 016) and sarcosine (3.6 ± 0.4 vs. 4.8 ± 0.6 μmol∙L-1; p = 0.006, η2 = 0.188) levels increased. Between the specific and competition phases, significant decreases in the resting levels of 1-methylhistidine (22.1 ± 19.4 vs. 9.6 ± 8.8 μmol∙L-1; p = 0.14, η2 = 0.19), 3-methylhistidine (7.1 ± 1.5 vs. 6.5 ± 1.6 μmol∙L-1; p = 0.009, η2 = 0.18), citrulline (40 ± 10 vs. 29 ± 4 μmol∙L-1; p = 0.05, η2 = 0.29), and ornithine (74 ± 15 vs. 56 ± 10 μmol∙L-1; p = 0.015, η2 = 185) were noticed. Also, for β-alanine and sarcosine, the pattern of response to exercise strongly changed between the training phases. Blood ammonia levels at exhaustion decreased between the transition and competition phases (32 ± 4 vs. 23 ± 5 μmol∙L-1; p < 0.001, η2 = 0.67), while lactate, the phenylalanine-tyrosine ratio, the glutamine-glutamate ratio, hematological parameters, and cardiorespiratory indices remained at similar levels. Conclusions: Speed-power training seems to affect PFAAs involved in skeletal muscle metabolic pathways responsible for neutralizing toxic ammonia (glutamine, arginine, citrulline, ornithine), attenuating the deleterious effects of H+ ions (histidine, β-alanine), and reducing exercise-induced protein breakdown (1- and 3-methylhistidine). Our findings suggest that sprint-oriented training supports metabolic pathways that are responsible for the removal of harmful metabolites produced during exercise.

Circulating Amino Acid Concentration after the Consumption of Pea or Whey Proteins in Young and Older Adults Affects Protein Synthesis in C2C12 Myotubes.

As older adults tend to reduce their intake of animal-source proteins, plant-source proteins may offer valuable resources for better protein intake. The aim of this study was to assess whether the pea proteins can be used to achieve blood amino acid levels that stimulate muscle protein synthesis. We measured variations in plasma amino acid concentrations in young and older adults given pea (NUTRALYS® S85 Plus) or whey proteins either alone or in a standardized meal. The effect of amino acid concentrations on protein synthesis in C2C12 myotubes was determined. In terms of results, plasma amino acid concentrations reflected the difference between the amino acid contents of whey and pea proteins. Blood leucine showed a greater increase of 91 to 130% with whey protein compared to pea protein, while the opposite was observed for arginine (A greater increase of 147 to 210% with pea compared to whey). Culture media prepared with plasmas from the human study induced age-dependent but not protein-type-dependent changes in myotube protein synthesis. In conclusion, pea and whey proteins have the same qualities in terms of their properties to maintain muscle protein synthesis. Pea proteins can be recommended for older people who do not consume enough animal-source proteins.

Leucine requirement determined in healthy young adult males using the indicator amino acid oxidation method

BackgroundPrevious studies proposed varying leucine requirements for adults ranging from 25 to 40 mg⋅kg−1⋅d−1, but often these studies did not test intakes exceeding 40 mg⋅kg−1⋅d−1. Data using the indicator amino acid oxidation (IAAO) method suggest a higher requirement of 55 mg⋅kg−1⋅d−1 on the basis of the total branched-chain amino acids requirement, but not leucine independently. ObjectivesThe IAAO method was used to determine the leucine requirement in healthy young adult males. MethodsTen healthy adult males (26.9 ± 1.87 y, mean ± SEM) were studied at 7 leucine intakes; each studied over a 3-d period. Following 2-d of preadaptation to adequate protein intake (1.0 g⋅kg−1⋅d−1), subjects received experimental diets containing the randomly assigned test leucine intake (10, 20, 30, 40, 50, 65, and 75 mg⋅kg−1⋅d−1) for 8 h. The rate of the release of 13CO2 from the oxidation of L-[1-13C]phenylalanine (F13CO2) was measured on the third day, and the leucine requirement was determined using mixed-effect change-point regression and the F13CO2 data in R. The 95% confidence interval was calculated using parametric bootstrap. The effect of leucine intake on the concentration of plasma amino acids, insulin, and glucose were assessed using repeated measures analysis of variance and linear mixed effects. ResultsThe mean leucine requirement was 33.6 mg⋅kg−1⋅d−1 with a lower and upper 95% confidence of 26.16, 41.04 mg⋅kg−1⋅d−1. Higher leucine intakes were associated with increased plasma leucine, and decreased valine, isoleucine, and serine concentrations. ConclusionsThe leucine requirement of young adult males is ∼34 mg⋅kg−1⋅d−1, which aligns with previously published tracer balance experiments.This trial was registered at http://clinicaltrials.gov (https://clinicaltrials.gov/study/NCT05394155?term=leucine%20young%20adult&rank=1) as NCT05394155.

Infant growth and tolerance with a formula based on novel native demineralized whey: A randomized double-blind pilot study.

The aim of the study was to evaluate the effects on infant growth and tolerance of a Test infant formula based on a novel whey extraction and demineralization process, compared to a Standard formula and a breastfed reference arm. Healthy term infants (n = 61) aged up to 21 days were randomized to Test or Control formula. A breastfed group (n = 39) served as a reference. Growth, tolerance, adverse events, and sleep were evaluated every month until 6 months of age. Plasma amino-acid concentrations at 3 months of age were measured in a subgroup population. Growth curves of all infants globally agreed with World Health Organization standards across the 6-month period study. Regarding tolerance, no difference between the formula-fed groups was observed on daily number of crying episodes, intensity or time to onset of regurgitations, and stool frequency or consistency, except at 5 months with infants in the Control group having more watery stools. Plasma concentration of some amino acids differed between the groups, especially tryptophan concentration which was higher in infants fed with the Test formula. In parallel, total sleep duration was longer in these infants at 2, 3, and 5 months of age, corresponding to an increase in daytime sleep. Test formula supported an adequate infant growth from birth to 6 months of age and was well-tolerated by all infants. An increase in total sleep at several months was also observed with the Test formula.

Timing of feeding a protein supplement on nitrogen balance and plasma amino acids during exercise recovery in horses.

Eight geldings weighing 544 ± 16 kg were used to evaluate feeding a postexercise protein meal on plasma amino acids during recovery. Horses were fed sweet feed, corn, grass hay and equal amounts of a protein pellet (32% CP) with meals (MP group) or postexercise (EP group). Horses exercised 1-2 h/day, 5 days/week, for 12 weeks. A pre and poststudy 4 days total urine and feces collection was conducted. Urine and fecal samples were analyzed for nitrogen (N) to calculate N balance. Blood samples were drawn immediately after and at 1 and 3 hpostexercise at the start and end of the study for plasma amino acid concentrations. Absorbed N and N retention were greater for the MP group compared to the EP group (p = 0.038, 0.033 respectively). An interaction revealed an increase in fecal N (p = 0.01) and decreased N digestibility for the MP group compared to the EP group at the end of the study. Plasma concentrations for 8 out of 14 amino acids were less for the EP group immediately after exercise compared to the MP group (p < 0.02). Plasma concentrations of lysine and arginine were greater for the EP group compared to the MP group at 1 and 3 hafter exercise (p < 0.05 and 0.04 respectively). Changes were different for 8 out of the 14 amino acids immediately post exercise, 7 out of 14 amino acids at 1 hpostexercise and 10 out of 14 amino acids at 3 hpostexercise with positive changes for the EP group and negative changes for the MP group. The EP group had improved supply of plasma amino acids in the recovery period that sustained for 3 hpostexercise and are indicative of better amino acid supply supporting muscle development.

Coingestion of Collagen With Whey Protein Prevents Postexercise Decline in Plasma Glycine Availability in Recreationally Active Men.

Whey protein ingestion during recovery from exercise increases myofibrillar but not muscle connective protein synthesis rates. It has been speculated that whey protein does not provide sufficient glycine to maximize postexercise muscle connective protein synthesis rates. In the present study, we assessed the impact of coingesting different amounts of collagen with whey protein as a nutritional strategy to increase plasma glycine availability during recovery from exercise. In a randomized, double-blind, crossover design, 14 recreationally active men (age: 26 ± 5years; body mass index: 23.8 ± 2.1kg·m-2) ingested in total 30g protein, provided as whey protein with 0g (WHEY), 5g (WC05); 10g (WC10), and 15g (WC15) of collagen protein immediately after a single bout of resistance exercise. Blood samples were collected frequently over 6hr of postexercise recovery to assess postprandial plasma amino acid kinetics and availability. Protein ingestion strongly increased plasma amino acid concentrations (p < .001) with no differences in plasma total amino acid availability between treatments (p > .05). The postprandial rise in plasma leucine and essential amino acid availability was greater in WHEY compared with the WC10 and WC15 treatments (p < .05). Plasma glycine and nonessential amino acid concentrations declined following whey protein ingestion but increased following collagen coingestion (p < .05). Postprandial plasma glycine availability averaged -8.9 ± 5.8, 9.2 ± 3.7, 23.1 ± 6.5, and 39.8 ± 11.0mmol·360min/L in WHEY, WC05, WC10, and WC15, respectively (incremental area under curve values, p < .05). Coingestion of a small amount of collagen (5g) with whey protein (25g) is sufficient to prevent the decline in plasma glycine availability during recovery from lower body resistance-type exercise in recreationally active men.

Association between Childhood Overweight and Altered Concentrations of Circulating Amino Acids.

(1) Background: Dysregulated serum amino acids (AA) are known to be associated with obesity and risk of Type 2 Diabetes (T2D) in adults, and recent studies support the same notion in the pubertal age. It is, however, unknown whether childhood overweight may already display alterations of circulating AA. (2) Methods: We used liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)-targeted metabolomics to determine plasma concentrations of AA and AA-related molecules in 36 children aged 7-12 years with normal weight or overweight. Clinical and anthropometric parameters were measured. (3) Results: Overweight in children is associated with an altered AA profile, with increased branched-chain amino acids (BCAA) and decreased glycine levels, with no clinically manifested metabolic conditions. Moreover, z-BMI was positively and negatively correlated with BCAA and glycine levels, respectively, even after adjustment for age and gender. We also found a correlation between the AA profile and clinical parameters such as lipids profile and glycemia. (4) Conclusions: A pattern of low glycine, and increased BCAA is correlated to z-BMI, total cholesterol, and triglycerides in overweight but otherwise healthy children. Our data suggest that, in childhood overweight, AA disturbances may precede other clinical parameters, thus providing an early indicator for the later development of metabolic disease.

Protein Ingredient Quality within Infant Formulas Impacts Plasma Amino Acid Concentrations in Neonatal Minipiglets

BackgroundInfant formulas (IFs), the only adequate substitute to human milk, are complex matrices that require numerous ingredients and processing steps that may impact protein digestion and subsequent amino acid (AA) absorption. ObjectivesThe objective was to understand the impact of the protein ingredient quality within IFs on postprandial plasma AA profiles. MethodsFour isonitrogenous and isocaloric IFs were produced at a semi-industrial scale using whey proteins from different origins (cheese compared with ideal whey) and denaturation levels (IF-A, -B, -C), and caseins with different supramolecular organizations (IF-C, -D). Ten Yucatan minipiglets (12- to 27-d-old) were used as a human infant model and received each IF for 3 d according to a Williams Latin square followed by a 2-d wash-out period. Jugular plasma was regularly sampled from 10 min preprandial to 4 h postprandial on the third day to measure free AAs, urea, insulin, and glucose concentrations. Data were statistically analyzed using a mixed linear model with diet (IFs), time, and sex as fixed factors and piglet as random factor. ResultsIFs made with cheese whey (IF-A and -B) elicited significantly higher plasma total and essential AA concentrations than IFs made with ideal whey (IF-C and -D), regardless of the pre- and postprandial times. Most of the differences observed postprandially were explained by AA homeostasis modifications. IFs based on cheese whey induced an increased plasma concentration of Thr due to both a higher Thr content in these IFs and a Thr-limiting degrading capability in piglets. The use of a nonmicellar casein ingredient led to reduced plasma content of AA catabolism markers (IF-D compared with IF-C). ConclusionsOverall, our results highlight the importance of the protein ingredient quality (composition and structure) within IFs on neonatal plasma AA profiles, which may further impact infant protein metabolism.

High-Moisture Extrusion of a Dietary Protein Blend Impairs In Vitro Digestion and Delays In Vivo Postprandial Plasma Amino Acid Availability in Humans

BackgroundIndustrial processing can alter the structural complexity of dietary proteins and, potentially, their digestion and absorption upon ingestion. High-moisture extrusion (HME), a common processing method used to produce meat alternative products, affects in vitro digestion, but human data are lacking. We hypothesized that HME of a mycoprotein/pea protein blend would impair in vitro digestion and in vivo postprandial plasma amino acid availability. MethodsIn Study A, 9 healthy volunteers completed 2 experimental trials in a randomized, double-blind, crossover design. Participants consumed a beverage containing 25 g protein from a “dry” blend (CON) of mycoprotein/pea protein (39%/61%) or an HME content-matched blend (EXT). Arterialized venous blood samples were collected in the postabsorptive state and regularly over a 5-h postprandial period to assess plasma amino acid concentrations. In Study B, in vitro digestibility of the 2 beverages were assessed using bicinchoninic acid assay and optical fluorescence microscopy at baseline and during and following gastric and intestinal digestion using the INFOGEST model of digestion. ResultsProtein ingestion increased plasma total, essential (EAA), and branched-chain amino acid (BCAA) concentrations (time effect, P < 0.0001) but more rapidly and to a greater magnitude in the CON compared with the EXT condition (condition × time interaction, P < 0.0001). This resulted in greater plasma availability of EAA and BCAA concentrations during the early postprandial period (0–150 min). These data were corroborated by the in vitro approach, which showed greater protein availability in the CON (2150 ± 129 mg/mL) compared with the EXT (590 ± 41 mg/mL) condition during the gastric phase. Fluorescence microscopy revealed clear structural differences between the 2 conditions. ConclusionsThese data demonstrate that HME delays in vivo plasma amino acid availability following ingestion of a mycoprotein/pea protein blend. This is likely due to impaired gastric phase digestion as a result of HME-induced aggregate formation in the pea protein.This trial was registered at clinicaltrials.gov as NCT05584358.

Increased hepatic glucagon sensitivity in totally pancreatectomised patients.

The metabolic phenotype of totally pancreatectomised patients includes hyperaminoacidaemia and predisposition to hypoglycaemia and hepatic lipid accumulation. We aimed to investigate whether the loss of pancreatic glucagon may be responsible for these changes. Nine middle-aged, normal-weight totally pancreatectomised patients, nine patients with type 1 diabetes (C-peptide negative), and nine matched controls underwent two separate experimental days, each involving a 150-min intravenous infusion of glucagon (4 ng/kg/min) or placebo (saline) under fasting conditions while any basal insulin treatment was continued. Glucagon infusion increased plasma glucagon to similar high physiological levels in all groups. The infusion increased hepatic glucose production and decreased plasma concentration of most amino acids in all groups, with more pronounced effects in the totally pancreatectomised patients compared with the other groups. Glucagon infusion diminished fatty acid re-esterification and tended to decrease plasma concentrations of fatty acids in the totally pancreatectomised patients but not in the type 1 diabetes patients. Totally pancreatectomised patients were characterised by increased sensitivity to exogenous glucagon at the level of hepatic glucose, amino acid, and lipid metabolism, suggesting that the metabolic disturbances characterising these patients may be rooted in perturbed hepatic processes normally controlled by pancreatic glucagon.

A panel of four plasma amino acids is a promising biomarker for newly diagnosed bladder cancer

BackgroundMetastasis and recurrence are the main causes of death in post-operative bladder cancer (BC), emphasizing the importance of exploring early-stage diagnostic markers. Serum biomarkers constitute a promising diagnostic approach for asymptomatic stage cancer as they are non-invasive, have high accuracy and low cost. AimsTo correlate concentrations of plasma amino acids with BC progression to assess their utility as an early-stage diagnostic. MethodsNewly diagnosed BC patients (n=95) and normal controls (n=96) were recruited during the period from 1 December 2018 to 30 December 2020. General and food frequency questionnaires established their basic information and dietary intake data. Venous blood samples were collected from fasting subjects and used to detect levels of plasma amino acids by liquid chromatography-mass spectrometry. Verification was performed on the GSE13507 transcriptome gene expression matrix of BC from Gene Expression Omnibus (GEO) database. ResultsEleven amino acids have been identified as altered in the plasma of newly diagnosed BC patients compared to controls (P < 0.05). Adjusted by gender, education, smoking and other factors, plasma ornithine level (OR = 0.256, 95% CI: 0.104 ∼ 0.630) is a protective factor for BC, plasma levels of methionine (OR = 3.460, 95% CI: 1.384 ∼ 8.651), arginine (OR = 3.851, 95% CI: 1.542 ∼ 9.616), and glutamate (OR = 3.813, 95% CI: 1.543 ∼ 9.419) are all risk factors for BC. ROC analysis demonstrated that the combination of plasma ornithine, methionine, arginine and glutamate could accurately diagnose BC (AUC = 0.84, 95% CI: 0.747 ∼ 0.833). In addition, the mRNA level of arginase 1 was decreased (P < 0.05), while the inducible nitric oxide synthase was increased significantly, which may be linked with the disturbance of arginine metabolism in BC patients. Further analysis of GEO database confirmed the role of arginine metabolism. ConclusionA biomarker panel containing four amino acids may provide a feasible strategy for the early diagnosis of BC. However, further validation is required through prospective studies.

Dietary CP and digestion kinetics influence BW loss, litter weight gain, and reproduction by affecting postprandial amino acid metabolism in lactating sows

To avoid a high body protein mobilization in modern lean sows during lactation, an adequate dietary amino acid (AA) supply and an efficient AA utilization are crucial. This study evaluated the effects of dietary CP and in vitro protein digestion kinetics on changes in sow body condition, litter weight gain, milk composition, blood metabolites, protein utilization efficiency and subsequent reproductive performance. We hypothesized that a slower digestion of dietary protein would improve AA availability and utilization. In total, 110 multiparous sows were fed one of four lactation diets in a 2 × 2 factorial design, with two CP concentrations: 140 g/kg vs 180 g/kg, and two protein digestion kinetics, expressed as a percentage of slow protein (in vitro degradation between 30 and 240 min): 8 vs 16% of total protein. Feeding sows the high CP diets reduced sow weight loss (Δ = 7.6 kg, P < 0.01), estimated body fat loss (Δ = 2.6 kg, P = 0.02), and estimated body protein loss (Δ = 1.0 kg, P = 0.08), but only at a high percentage of slow protein. A higher percentage of slow protein increased litter weight gain throughout lactation (Δ = 2.6 kg, P = 0.04) regardless of CP concentrations, whereas a higher CP only increased litter weight gain during week 3 of lactation (Δ = 1.2 kg, P = 0.01). On Day 15 postfarrowing, serial blood samples were taken from a subsample of sows fed with the high CP diets. In these sows, a high percentage of slow protein resulted in higher plasma AA concentrations at 150 and 180 min after feeding (Δ = 0.89, P = 0.02, Δ = 0.78, P = 0.03, mmol/L, respectively) and lower increases in urea at 90 and 120 min after feeding (Δ = 0.67, P = 0.04, Δ = 0.70, P = 0.03, mmol/L, respectively). The higher dietary CP concentration increased total nitrogen loss to the environment (Δ = 604 g, P < 0.01) with a reduction of protein efficiency (Δ = 14.8%, P < 0.01). In the next farrowing, a higher percentage of slow protein increased subsequent liveborn litter size (Δ = 0.7, P < 0.05). In conclusion, feeding sows with a high dietary CP concentration alleviated maternal weight loss during lactation when the dietary protein digestion rate was slower, but lowered protein efficiency. A slower protein digestion improved litter weight gain, possibly by reducing AA oxidation and improving plasma AA availability, thus, improving protein efficiency.

EFFECT OF SPERMS FREEZABILITY ON SOME SEMEN ATTRIBUTES AND AMINO ACID CONCENTRATIONS IN SEMINAL PLASMA OF HOLSTEIN BULLS

This study investigated the effect of different sperm freezability on some semen characteristics and amino acid concentrations in the seminal plasma of Holstein bulls cryopreserved for two years. The semen straws (0.25 ml) that cryopreserved for two years were divided into three equal groups (7 bulls per group) according to the sperm’s freezability: medium (73.02%; F1), good (83.76%; F2), and high (91.20%; F3). The F1 bulls were superior (P≤ 0.05) in sperm’s cell individual motility (SCIM) for fresh semen as compared with F2 and F3 bulls. The F2 and F3 groups were superior (P≤ 0.01) to the F1 group in live sperm percentage at cryopreservation. The sperm’s DNA damage percentage was lesser (P≤ 0.05) in the F1 and F3 groups as compared with the F2 group. The differences among groups in normal sperm percentage, sperm’s plasma membrane and acrosome integrity percentage, malondialdehyde, and total antioxidant concentrations lacked significance. The essential and non-essential amino acid concentrations in seminal plasma did not differ among groups. In conclusion, sperm freezability influenced some semen attributes but did not affect amino acid concentrations in the seminal plasma of Holstein bulls.

Dietary crude protein and protein solubility manipulation enhances intestinal nitrogen absorption and mitigates reactive nitrogen emissions through gut microbiota and metabolome reprogramming in sheep

Dietary nutrient manipulation (e.g. protein fractions) could lower the environmental footprints of ruminants, especially reactive nitrogen (N). This study investigated the impacts of dietary soluble protein (SP) levels with decreased crude protein (CP) on intestinal N absorption, hindgut N metabolism, fecal microbiota and metabolites, and their linkage with N metabolism phenotype. Thirty-two male Hu sheep, with an age of six months and an initial BW of 40.37 ± 1.18 kg, were randomly assigned to four dietary groups. The control diet (CON), aligning with NRC standards, maintained a CP content of 16.7% on a dry matter basis. Conversely, the experimental diets (LPA, LPB, and LPC) featured a 10% reduction in CP compared with CON, accompanied by SP adjustments to 21.2%, 25.9%, and 29.4% of CP, respectively. Our results showed that low-protein diets led to significant reductions in the concentrations of plasma creatinine, ammonia, urea N, and fecal total short-chain fatty acids (SCFA) (P < 0.05). Notably, LPB and LPC exhibited increased total SCFA and propionate concentrations compared with LPA (P < 0.05). The enrichment of the Prevotella genus in fecal microbiota associated with energy metabolism and amino acid (AA) biosynthesis pathways was evident with SP levels in low-protein diets of approximately 25% to 30%. Moreover, LPB and LPC diets demonstrated a decrease in fecal NH4+–N and NO2−–N contents as well as urease activity, compared with CON (P < 0.05). Concomitantly, reductions in fecal glutamic acid dehydrogenase gene (gdh), nitrite reductase gene (nirS), and nitric oxide reductase gene (norB) abundances were observed (P < 0.05), pointing towards a potential reduction in reactive N production at the source. Of significance, the up-regulation of mRNA abundance of AA and peptide transporters in the small intestine (duodenum, jejunum, and ileum) and the elevated concentration of plasma AA (e.g. arginine, methionine, aspartate, glutamate, etc.) underscored the enhancement of N absorption and N efficiency. In summary, a 10% reduction in CP, coupled with an SP level of approximately 25% to 30%, demonstrated the potential to curtail reactive N emissions through fecal Prevotella enrichment and improve intestinal energy and N utilization efficiency.

Plant Protein Blend Ingestion Stimulates Postexercise Myofibrillar Protein Synthesis Rates Equivalently to Whey in Resistance-Trained Adults.

Whey protein ingestion is typically considered an optimal dietary strategy to maximize myofibrillar protein synthesis (MyoPS) after resistance exercise. Although single-source plant protein ingestion is typically less effective, at least partly, due to less favorable amino acid profiles, this could theoretically be overcome by blending plant-based proteins with complementary amino acid profiles. We compared the postexercise MyoPS response after the ingestion of a novel plant-derived protein blend with an isonitrogenous bolus of whey protein. Ten healthy, resistance-trained, young adults (male/female: 8/2; age: 26 ± 6 yr; BMI: 24 ± 3 kg·m -2 ) received a primed continuous infusion of L-[ ring - 2 H 5 ]-phenylalanine and completed a bout of bilateral leg resistance exercise before ingesting 32 g protein from whey (WHEY) or a plant protein blend (BLEND; 39.5% pea, 39.5% brown rice, 21.0% canola) in a randomized, double-blind crossover fashion. Blood and muscle samples were collected at rest, and 2 and 4 h after exercise and protein ingestion, to assess plasma amino acid concentrations, and postabsorptive and postexercise MyoPS rates. Plasma essential amino acid availability over the 4 h postprandial postexercise period was ~44% higher in WHEY compared with BLEND ( P = 0.04). From equivalent postabsorptive values (WHEY, 0.042 ± 0.020%·h -1 ; BLEND, 0.043 ± 0.015%·h -1 ) MyoPS rates increased after exercise and protein ingestion (time effect; P < 0.001) over a 0- to 2-h period (WHEY, 0.085 ± 0.037%·h -1 ; BLEND, 0.080 ± 0.037%·h -1 ) and 2- to 4-h period (WHEY, 0.085 ± 0.036%·h -1 ; BLEND, 0.086 ± 0.034%·h -1 ), with no differences between conditions during either period or throughout the entire (0-4 h) postprandial period (time-condition interactions; all P > 0.05). Ingestion of a novel plant-based protein blend stimulates postexercise MyoPS to an equivalent extent as whey protein, demonstrating the utility of plant protein blends to optimize postexercise skeletal muscle reconditioning.