Serum Amino Acid Concentrations Research Articles

Targeted metabolomic profiles of serum amino acids are independently correlated with malnutrition in older adults.

Malnutrition is a common geriatric syndrome that is closely associated with adverse clinical outcomes and poses significant harm to older adults. Early assessment of nutritional status plays a crucial role in preventing and intervening in cases of malnutrition. However, there is currently a lack of measurable methods and biomarkers to evaluate malnutrition in older adults accurately. The aim of this study is to investigate the independent correlation between serum levels of amino acids and malnutrition in older adults, and to identify effective metabolomics biomarkers that can aid in the early detection of geriatric malnutrition. A total of 254 geriatric medical examination participants from Beijing Hospital were included in the study, consisting of 182 individuals with normal nutritional status (Normal group) and 72 patients at risk of malnutrition or already malnourished (MN group). Malnutrition was assessed using the Mini-Nutritional Assessment Short-Form (MNA-SF). Demographic data were collected, and muscle-related and lipid indexes were determined. Serum amino acid concentrations were measured using isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). The correlation between serum amino acid levels and malnutrition was analyzed using non-parametric tests, partial correlation analysis, linear regression, and logistic regression. The geriatric MN group exhibited significantly lower serum aromatic amino acid levels (P < 0.05) compared to the normal group. A positive correlation was observed between serum aromatic amino acid levels and the MNA-SF score (P = 0.002), as well as with known biomarkers of malnutrition such as body mass index (BMI) (P < 0.001) and hemoglobin (HGB) (P = 0.005). Multivariable logistic or linear regression analyses showed that aromatic amino acid levels were negatively correlated with MN and positively correlated with the MNA-SF score, after adjusting for some confounding factors, such as age, gender, BMI, smoking status, history of dyslipidemia, diabetes mellitus and frailty. Stratified analyses revealed that these trends were more pronounced in individuals without a history of frailty compared to those with a history of frailty, and there was an interaction between aromatic amino acid levels and frailty history (P = 0.004). Our study suggests that serum aromatic amino acids are independently associated with malnutrition in older adults. These results have important implications for identifying potential biomarkers to predict geriatric malnutrition or monitor its progression and severity, as malnutrition can result in poor clinical outcomes.

Using an Interpretable Amino Acid-Based Machine Learning Method to Enhance the Diagnosis of Major Depressive Disorder.

Background: Major depressive disorder (MDD) is a leading cause of disability worldwide. At present, however, there are no established biomarkers that have been validated for diagnosing and treating MDD. This study sought to assess the diagnostic and predictive potential of the differences in serum amino acid concentration levels between MDD patients and healthy controls (HCs), integrating them into interpretable machine learning models. Methods: In total, 70 MDD patients and 70 HCs matched in age, gender, and ethnicity were recruited for the study. Serum amino acid profiling was conducted by means of chromatography-mass spectrometry. A total of 21 metabolites were analysed, with 17 from a preset amino acid panel and the remaining 4 from a preset kynurenine panel. Logistic regression was applied to differentiate MDD patients from HCs. Results: The best-performing model utilised both feature selection and hyperparameter optimisation and yielded a moderate area under the receiver operating curve (AUC) classification value of 0.76 on the testing data. The top five metabolites identified as potential biomarkers for MDD were 3-hydroxy-kynurenine, valine, kynurenine, glutamic acid, and xanthurenic acid. Conclusions: Our study highlights the potential of using an interpretable machine learning analysis model based on amino acids to aid and increase the diagnostic accuracy of MDD in clinical practice.

Metabolomics profiling reveals low blood tyrosine levels as a metabolic feature of newborns from systemic lupus erythematosus pregnancies.

Pregnancy outcomes of patients with systemic lupus erythematosus (SLE) have improved over the past four decades, leading to an increased desire for pregnancy among this cohort. However, the offspring of patients with SLE still face the risks of preterm birth, low birth weight, learning disabilities, and neurological disorders, while the causes underlying these risks remain unclear. In this study, we analyzed the blood metabolic features of neonates born to 30 SLE patients and 52 healthy control mothers by employing tandem mass spectrometry with the dual aims of identifying the etiology of metabolic features specific to infants born from mothers with SLE and providing new insights into the clinical management of such infants. We found significant differences in serum metabolite levels between infants born from mothers with SLE and those born from mothers without SLE, including 15 metabolites with reduced serum levels. Further analysis revealed a disrupted tyrosine metabolism pathway in the offspring of mothers with SLE. By constructing a composite model incorporating various factors, such as serum tyrosine levels, gestational age, and birth weight, we were able to accurately differentiate between newborns of SLE and non-SLE pregnancies. Our data reveal significant differences in serum concentrations of amino acids and acylcarnitines in newborns born to mothers with SLE. We conclude that the reduction of blood L-tyrosine levels is a feature that is characteristic of adverse neurological outcomes in infants born from mothers with SLE.

Association between serum trace element, mineral, and amino acid levels with non-alcoholic fatty liver disease (NAFLD) in adult women

The objective of the present study is assessment of serum trace element and amino acid levels in non-alcoholic fatty liver disease (NAFLD) patients with subsequent evaluation of its independent associations with markers of liver injury and metabolic risk. Materials and methods140 women aged 20–90 years old with diagnosed NAFLD and 140 healthy women with a respective age range were enrolled in the current study. Analysis of serum and hair levels of trace elements and minerals was performed with inductively-coupled plasma mass-spectrometry (ICP-MS). Serum amino acid concentrations were evaluated by high-pressure liquid chromatography (HPLC) with UV-detection. In addition, routine biochemical parameters including liver damage markers, alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT), were assessed spectrophotometrically. ResultsThe findings demonstrated that patients with NAFLD were characterized by higher ALT, GGT, lactate dehydrogenase (LDH) and cholinesterase (CE) activity, as well as increased levels of total cholesterol, low-density lipoprotein cholesterol, triglycerides, and uric acid. NAFLD patients were characterized by reduced serum and hair Co, Se, and Zn levels, as well as hair Cu content and serum Mn concentrations in comparison to controls. Circulating Ala, Cit, Glu, Gly, Ile, Leu, Phe, and Tyr levels in NAFLD patients exceeded those in the control group. Multiple linear regression demonstrated that serum and hair trace element levels were significantly associated with circulating amino acid levels after adjustment for age, BMI, and metabolic parameters including liver damage markers. ConclusionIt is proposed that altered trace element handling may contribute to NAFLD pathogenesis through modulation of amino acid metabolism.

Investigation of amino acid profile alterations in maternal serum for early diagnosis of anembryonic pregnancy with high performance liquid chromatography-mass spectrometry

BackgroundAnembryonic pregnancy affects 12–15 % of clinically recognized pregnancies and a previous anembryonic pregnancy is an independent risk factor for future anembryonic pregnancy. This study aimed to investigate alternations in maternal amino acid profiles and analyze the diagnostic accuracy of amino acid biomarkers for anembryonic pregnancy in the early stage. MethodsFasting serum from anembryonic pregnancy patients (n = 103) and healthy pregnancies (n = 97) was collected, and amino acid concentrations were determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS). A receiver operating characteristic (ROC) curve was used to evaluate the diagnostic performance of each of the amino acid biomarkers and the amino acid profile index for anembryonic pregnancy screening. ResultsThe concentrations of 15 amino acids were significantly different between anembryonic pregnancy patients and healthy controls, and most of them were significantly higher at 7 weeks’ gestational age in anembryonic pregnancy subjects. The area under the curve (AUC) based on an amino acid profile index combined with alanine, citrulline, aspartic acid, threonine, serine and isoleucine was 0.90 (sensitivity 82.76 %, specificity 83.64 %) for distinguishing early anembryonic pregnancy from healthy controls. ConclusionMaternal serum amino acid concentrations were significantly elevated in anembryonic pregnancy patients. The diagnostic potential of amino aicds for anembryonic pregnancy was verified, and the diagnostic efficiency was improved in the use of the amino acid profile index. The amino acid profile is expected to be applied for the risk screening of early-stage of anembryonic pregnancy in the future.

Dietary lipoic acid alleviates autism-like behavior induced by acrylamide in adolescent mice: the potential involvement of the gut-brain axis.

Consuming fried foods has been associated with an increased susceptibility to mental health disorders. Nevertheless, the impact of alpha-lipoic acid (α-LA, LA) on fried food-induced autism-like behavior remains unclear. This study aimed to explore how LA affects autism-related behavior and cognitive deficits caused by acrylamide in mice, a representative food hazard found in fried foods. This improvement was accomplished by enhanced synaptic plasticity, increased neurotrophin expression, elevated calcium-binding protein D28k, and restored serotonin. Additionally, LA substantially influenced the abundance of bacteria linked to autism and depression, simultaneously boosted short-chain fatty acid (SCFA) levels in fecal samples, and induced changes in serum amino acid concentrations. In summary, these findings suggested that exposure to acrylamide in adolescent mice could induce the development of social disorders in adulthood. LA showed promise as a nutritional intervention strategy to tackle emotional disorders during adolescence.

Metabolomics analysis to interpret changes in physiological and metabolic responses to chronic heat stress in Pekin ducks

Heat stress (HS) is a major environmental threat that affects duck production in subtropical and tropical regions, especially in summer. This study aimed to evaluate the physiological and metabolic responses of Pekin ducks to chronic HS conditions via liquid chromatography-mass spectrometry (LC-MS) using a paired-fed (PF) experimental design. On the basis of equivalent feed intake (HS vs. PF), HS significantly reduced growth performance and the percentage of leg and breast muscles, however, markedly increased the percentage of abdominal fat and breast skin fat. Serum metabolomics results revealed that heat-stressed ducks showed enhanced glycolysis and pentose phosphate pathways, as demonstrated by higher glucose 6-phosphate and 6-phogluconic acid levels in the PF vs. HS comparison. HS decreased hepatic mRNA levels of mitochondrial fatty acid β-oxidation-related genes (MCAD and SCAD) compared to the PF group, resulting in acetylcarnitine accumulation in serum. Moreover, HS elevated the concentrations of serum amino acids and mRNA levels of ubiquitination-related genes (MuRF1 and MAFbx) in the skeletal muscle and amino acid transporter-related genes (SLC1A1 and SLC7A1) and gluconeogenesis-related genes (PCK1 and PCase) in the liver compared to the PF group. When compared to the normal control group (NC), HS further decreased growth performance, but it elevated the abdominal fat rate. However, increased mRNA levels of ubiquitination-related genes and serum amino acid accumulation were not observed in the HS group compared to the NC group, implying that reduced feed intake masked the effect of HS on skeletal muscle breakdown and is a form of protection for the organism. These results suggest that chronic HS induces protein degradation in the skeletal muscle to provide amino acids for hepatic gluconeogenesis to provide sufficient energy, as Pekin ducks under HS conditions failed to efficiently oxidise fatty acids and ketones in the mitochondria, leading to poor growth performance and slaughter characteristics.

L-Lysine supplementation affects dietary protein quality and growth and serum amino acid concentrations in rats

Single amino acid (AA) supplementations in foods are increasing, however their potential nutritional and physiological impacts are not fully understood. This study examined the effects of l-lysine (Lys) supplementation on protein quality of diets, serum AA concentrations and associations between the ratio of supplemental Lys to dietary protein (X) with body weight gain (BWG) in Sprague–Dawley male rats. Rats were fed one of 10 diets containing either 7% or 20% casein and supplemented with 0% (Control), 1.5%, 3%, 6% Lys or 6% Lys + 3% l-arginine (Arg) (8 rats/diet group) for 1 week. Lys supplementation reduced the protein quality of the casein-based diets (p < 0.01). BWG was reduced by supplemental Lys when X > 0.18. Free Lys supplementation dose-dependently increased serum Lys levels (p < 0.01), while increased protein-bound Lys (1.4% vs 0.52%) had little effect on serum Lys (p > 0.05). In the 7% casein diets, ≥ 1.5% supplemental Lys reduced serum alanine, asparagine, glycine, isoleucine, leucine, serine, tyrosine, valine, carnitine, ornithine, and increased urea. Supplementation of ≥ 3% Lys additionally reduced tryptophan and increased histidine, methionine and α-aminoadipic acid (α-AAA) compared to the Control (p < 0.05). In the 20% casein diets, addition of ≥ 1.5% Lys reduced serum asparagine and threonine, and ≥ 3% Lys reduced leucine, proline, tryptophan, valine, and ornithine, and 6% Lys reduced carnitine, and increased histidine, methionine, and α-AAA. Overall, this study showed that free Lys supplementation in a Lys-sufficient diet reduced the protein quality of the diets and modified the serum concentrations of many amino acids. Excess free Lys intake adversely affected growth and utilization of nutrients due to AA imbalance or antagonism. Overall lower protein intake increases susceptibility to the adverse effects of Lys supplementation.

Cord Blood Metabolite Profiles and Their Association with Autistic Traits in Childhood.

Autism Spectrum Disorder (ASD) is a diverse neurodevelopmental condition. Gene-environmental interactions in early stages of life might alter metabolic pathways, possibly contributing to ASD pathophysiology. Metabolomics may serve as a tool to identify underlying metabolic mechanisms contributing to ASD phenotype and could help to unravel its complex etiology. In a population-based, prospective cohort study among 783 mother-child pairs, cord blood serum concentrations of amino acids, non-esterified fatty acids, phospholipids, and carnitines were obtained using liquid chromatography coupled with tandem mass spectrometry. Autistic traits were measured at the children's ages of 6 (n = 716) and 13 (n = 648) years using the parent-reported Social Responsiveness Scale. Lower cord blood concentrations of SM.C.39.2 and NEFA16:1/16:0 were associated with higher autistic traits among 6-year-old children, adjusted for sex and age at outcome. After more stringent adjustment for confounders, no significant associations of cord blood metabolites and autistic traits at ages 6 and 13 were detected. Differences in lipid metabolism (SM and NEFA) might be involved in ASD-related pathways and are worth further investigation.

Sex-related differences in within-subject biological variation estimates for 22 essential and non-essential amino acids

BackgroundMeasurement of serum amino acid (AA) concentrations is important in particular for the diagnosis and monitoring of inborn errors of AA metabolism. To ensure optimal clinical interpretation of AAs, reliable biological variation (BV) data are essential. In the present study, we derived BV data for 22 non-essential, conditionally essential, and essential AAs and assessed differences in BV of AAs related to sex. MethodsMorning blood samples were drawn from 66 subjects (31 males and 35 females) once a week for 10 consecutive weeks. All samples were analyzed in duplicate using liquid chromatography-tandem mass-spectrometry. The data were assessed for outliers, trends, normality and variance homogeneity analysis prior to estimating within-subject (CVI) and between-subject (CVG) BV. ResultsCVI estimates ranged from 9.0 % for histidine (male) to 33.0 % for taurine (male). CVI estimates in males and females were significantly different for all AAs except for aspartic acid, citrulline and phenylalanine, in most cases higher in females than in males. Apart from for arginine, CVG estimates in males and females were similar. ConclusionsIn this highly powered BV study, we provide updated BV estimates for 22 AAs and demonstrate that for most AAs, CVI estimates differ between males and females, with implications for interpretation and use of AAs in clinical practice.

Genetic and Lifestyle-Related Factors Influencing Serum Hyper-Propionylcarnitine Concentrations and Their Association with Metabolic Syndrome and Cardiovascular Disease Risk.

The genetic and environmental determinants of serum propionylcarnitine concentrations (PC) remain largely unexplored. This study investigated the impact of genetic and environmental factors on serum propionylcarnitine levels in middle-aged and elderly participants from the Ansan/Ansung cohort of the Korean Genome and Epidemiology Study. Our goal was to understand the role of PC on the risk of metabolic syndrome (MetS) leading to cardiovascular disease, particularly concerning branched-chain amino acid (BCAA) metabolism. We analyzed participants' demographic, lifestyle, and biochemical data with and without MetS. Serum metabolite concentrations, including carnitine, acylcarnitine, and amino acid concentrations, were measured, and the components of MetS were evaluated. Genetic variants associated with low and high PC were selected using genome-wide association studies after adjusting for MetS-related parameters. Further, genetic variants and lifestyle factors that interacted with the polygenic risk score (PRS) were analyzed. Participants with MetS were older and less educated, and their alcohol intake was higher than non-MetS participants. PC was significantly associated with the MetS risk and increased the serum levels of BCAAs and other amino acids. Higher PC positively correlated with MetS components, insulin resistance, and cardiovascular risk factors. Intake of calcium, sodium, and vitamin D were inversely associated with PC, but coffee consumption was positively linked to PC. Multiple C2 And Transmembrane Domain Containing-1 (MCTP1)_rs4290997, Kinesin Family Member-7 (KIF7)_rs2350480, Coagulation Factor-II (F2)_rs2070850, Peroxisomal Biogenesis Factor-3 (PEX3)_rs223231, TBC1 Domain Family Member-22A (TBC1D22A)_rs910543, and Phospholipase A2 Group-IV-C (PLA2G4C)_rs7252136 interact with each other to have a threefold influence on PC. The PRS for the six-genetic variant model also interacted with age; the diet rich in beans, potato, and kimchi; and smoking status, influencing PC. In conclusion, elevated PC was associated with MetS and cardiovascular disease risk, suggesting their potential as disease biomarkers.

Time-resolved concentrations of serum amino acids, one-carbon metabolites and B-vitamin biomarkers during the postprandial and fasting state: the Postprandial Metabolism in Healthy Young Adults (PoMet) Study.

Metabolomics has been utilised in epidemiological studies to investigate biomarkers of nutritional status and metabolism in relation to non-communicable diseases. However, little is known about the effect of prandial status on several biomarker concentrations. Therefore, the aim of this intervention study was to investigate the effect of a standardised breakfast meal followed by food abstinence for 24 h on serum concentrations of amino acids, one-carbon metabolites and B-vitamin biomarkers. Thirty-four healthy subjects (eighteen males and sixteen females) aged 20-30 years were served a breakfast meal (∼500 kcal) after which they consumed only water for 24 h. Blood samples were drawn before and at thirteen standardised timepoints after the meal. Circulating concentrations of most amino acids and metabolites linked to one-carbon metabolism peaked within the first 3 h after the meal. The branched-chain amino acids steadily increased from 6 or 8 hours after the meal, while proline decreased in the same period. Homocysteine and cysteine concentrations immediately decreased after the meal but steadily increased from 3 and 4 hours until 24 h. FMN and riboflavin fluctuated immediately after the meal but increased from 6 h, while folate increased immediately after the meal and remained elevated during the 24 h. Our findings indicate that accurate reporting of time since last meal is crucial when investigating concentrations of certain amino acids and one-carbon metabolites. Our results suggest a need for caution when interpretating studies, which utilise such biomarkers, but do not strictly control for time since the last meal.

Amino acid profiles, disease activity, and protein intake in adult patients with Crohn's disease.

Crohn's disease (CD) is an immune-mediated inflammatory disorder of the gastrointestinal tract with a relapsing-remitting course. Amino acids (AAs) may play critical roles in the intestinal manifestations of disease, due to their involvement in many metabolic and immune functions. The present study aimed to explore serum AA concentrations in adult patients with CD, looking into their variations due to disease activity, surgery and protein content of diet. Eventually, the link between AAs and inflammatory markers was also assessed. Consecutive adult patients aged 18-65 years with diagnosis of CD were recruited. All participants underwent anthropometry and were instructed to fill in a 3-day food record to assess protein intake. Disease activity was clinically defined using the Crohn's Disease Activity Index (CDAI), while blood samples were taken to analyze serum AA profile and inflammatory markers. A total of 103 patients with CD (61 men and 42 women; age:39.9 ± 13.9 years, BMI: 23.4 ± 3.51 kg/m2) were included. Tryptophan levels were found to be remarkably decreased in most subjects, unrelated to disease activity. On the contrary, concentration of lysine, leucine, valine and glutamine decreased in active versus quiescent CD patients, while aspartic acid, glutamate and glycine increased. The latter AAs were also directly correlated with CDAI and serum interleukin (IL)- 1β concentration. Considering the total protein intake, expressed as g/kg/body weight, we observed a reduction in some essential AAs in patients with unmet protein requirements compared to patients who met the recommendation. In conclusion, specific AAs varied according to disease activity and protein intake, adjusted to body weight and disease status. Glu and Asp concentrations raised with increasing IL-1β. However, extensive research is needed to understand the mechanisms underpinning the link between variation in serum AAs, disease activity and protein intake in patients with CD.

Fermentation characteristics of different sources of dietary fiber in vitro and impacts on growth performance, nutrient digestibility and blood para-meters of piglets

This study aimed to assess the effect of various source of high-fiber ingredients on growth performance, apparent digestibility of nutrients, and blood para- meters of piglets by investigating their in vitro fermentation characteristics. A total of 300 healthy crossbred piglets were randomly allocated to one of five diets including corn-soybean meal basal diet (CON), sugar beet pulp (SBP), soybean hull (SBH), fermented distillers’ grains (FDG), and kelp powder (KP). In vitro fermentation analysis revealed that the predominant short-chain fatty acids produced were acetate and valerate. Sugar beet pulp and kelp powder exhibited rapid fermentation rates, in contrast to SBH, oat bran, and FDG. The apparent total tract digestibility of dry matter (P < 0.05), gross energy (P < 0.05), and crude protein were decreased (P < 0.001) in different fiber diets than the CON diet. The serum concentration of threonine was increased by feeding fibers diets (P < 0.05). In conclusion, a diet containing 3% SBP (with a soluble-to-insoluble dietary fiber ratio of 17.04%) showed the best effects on increasing nutrients digestibility and serum amino acid concentrations. These findings may inform future applications of SBP in piglet nutrition.

Dietary Acid Load Correlates with Serum Amino Acid Concentrations after a Four-Week Intervention with Vegan vs. Meat-Rich Diets: A Secondary Data Analysis.

Chronic low-grade metabolic acidosis is now a common phenomenon in the Western world. The high dietary intake of sulfur-containing amino acids in the form of processed meats results in an excessive release of acid in the form of protons and non-metabolizable acidic anions. The kidneys produce increasing amounts of ammonia to excrete this acid. This process requires the breakdown of the nitrogenous amino acid glutamine, which the body provides by breaking down muscle tissue. Hitherto not examined, we hypothesized that a high dietary acid load (DAL) could alter the serum concentrations of selected amino acids. Using secondary data from a 4-week dietary intervention study conducted in 2017, we examined the associations between various amino acids and DAL in n = 42 individuals who either consumed a meat-rich or vegan diet. Results from this secondary data analysis suggested that DAL (as measured by the potential renal acid load and net endogenous acid production) is positively correlated with higher serum concentrations of lysine and 1-methyl-histidine (r = 0.50 and 0.43, respectively) and negatively correlated with glutamine and glycine (r = -0.43 and -0.47, respectively). The inverse association with glycine and glutamine warrants special attention, as both play an important role in many metabolic disorders and the immune system.

Oral Administration of Animal and Plant Protein Mixture with Lactiplantibacillus plantarum IDCC 3501 Improves Protein Digestibility

A combined usage of animal and plant proteins-mixture could aid to solve environmental and social problems arising from the use of animal protein alone, while also improving the taste and texture of plant protein. Protein mixtures could be a better protein source due to the high availability of amino acids in the body compared with single proteins. Consuming proteins with probiotics can provide more beneficial health effects by helping to hydrolyze protein and absorb amino acids in the body. In this study, coadministration of an animal and plant protein mixture with a high concentration of probiotics was investigated to increase protein digestibility and amino acids absorbability in a mice model. Lactiplantibacillus plantarum IDCC 3501, which has the maximum ability to hydrolyze a protein mixture, composed of soybean protein and milk protein, was selected, and the changes in mice (C57BL/6J, male, six weeks) were investigated after the coadministration of protein mixture and 5 × 108 or 5 × 109 CFU/mL of L. plantarum for eight weeks. Normal diet, high-protein diet (HPD), and HPD supplementing L. plantarum were separately administered to mice. Food and water consumption of the mice did not differ depending on diet type. Measurements of the serum concentrations of amino acids showed that the absorption of aspartate, glutamate, isoleucine, leucine, valine, and lysine increased when high concentrations of protein and probiotics were administered. Thus, high L. plantarum concentrations could be a protein diet supplementation to improve health by promoting the absorption of amino acids.

Effect of Ornithine α-Ketoglutarate on Intestinal Microbiota and Serum Inflammatory Cytokines in Dextran Sulfate Sodium Induced Colitis.

Ornithine α-ketoglutarate (OKG), a nutritional compound, is an amino acid salt with anti-oxidative and anti-inflammatory effects on humans and animals. Ulcerative colitis (UC), as an inflammatory bowel disease (IBD), leads to chronic intestinal inflammatory dysfunction. This study evaluated the optimal dosage of OKG in healthy mice. Then, a mouse model of acute colitis was established using dextran sodium sulfate (DSS), and the preventive effect of OKG on DSS-induced colitis in mice was explored through analysis of serum inflammatory cytokines and fecal microbiota. Initially, the mice were randomly divided into a control group, a group given a low dose of OKG (LOKG: 0.5%), a group given a medium dose of OKG (MOKG: 1%), and a group given a high dose of OKG (HOKG: 1.5%); they remained in these groups for the entire 14-day experimental period. Our results demonstrated that 1% OKG supplementation increased body weight, serum growth hormone (GH), insulin (INS), alkaline phosphatase (ALP), Tyr, and His and decreased urea nitrogen (BUN), NH3L, and Ile. Then, a 2 × 2 factor design was used for a total of 40 mice, with diet (a standard diet or a 1% OKG diet) and challenge (4% DSS or not) as the main factors. During days 14 to 21, the DSS mice were administered 4% DSS to induce colitis. The results revealed that OKG alleviated weight loss and reversed the increases in colonic histological damage induced by DSS. OKG also increased serum IL-10 secretion. Moreover, OKG enhanced the abundance of Firmicutes and decreased that of Bacteriodetes at the phylum level and particularly enhanced the abundance of Alistipes and reduced that of Parabacterioides at the genus level. Our results indicated that OKG promotes growth performance and hormone secretion and regulates serum biochemical indicators and amino acid concentrations. Furthermore, 1% OKG supplementation prevents DSS-induced colitis in mice via altering microbial compositions and reducing the secretion of inflammatory cytokines in serum.

Critical illness myopathy and trajectory of recovery in acute kidney injury requiring continuous renal replacement therapy: a prospective observational trial protocol

IntroductionAcute kidney injury requiring renal replacement therapy (AKI-RRT) is common in the intensive care unit (ICU) and is associated with significant morbidity and mortality. Continuous RRT (CRRT) non-selectively removes large...

Serum concentrations of amino acids and tryptophan metabolites are affected by consumption of a light breakfast: a clinical intervention study in adults with overweight or obesity

BackgroundEpidemiological studies often investigate amino acids and their metabolites as biomarkers, but do not always consistently use fasting or non-fasting blood samples, or may lack information on the prandial status of the study participants. Since little information is available on the effects of the prandial status on many biomarkers, and since blood is typically sampled early in the day with participants in a fasting state or after having consumed a light meal in many trials, the main purpose of this study was to investigate the short-term effects of a light breakfast on serum concentrations of amino acids and related metabolites.MethodsBlood was collected from sixty-three healthy adults (36 women) in the fasting state and at set times for 120 min after intake of a light breakfast with low protein content (14 g protein, 2218 kJ). Relative changes in serum biomarker concentrations from fasting to postprandial serum concentrations were tested using T test.ResultsThe serum concentrations of 13 of the 20 measured amino acids were significantly changed 60 min following breakfast intake, with the most marked effects seen as increases in alanine (34%) and proline (45%) concentrations. The response did not reflect the amino acid composition of the breakfast. The concentrations of seven kynurenine metabolites were significantly decreased after breakfast.ConclusionConsumption of a light breakfast affected serum concentrations of several amino acids and related metabolites, underlining the importance of having information regarding the participants’ prandial state at the time of blood sampling in studies including these biomarkers.Trial registrationThis trial was registered at clinicaltrials.gov as NCT02350595 (registered January 2015).

Effect of dl-methionine supplementation above requirement on performance; intestinal morphology, antioxidant activity, and gene expression; and serum concentration of amino acids in heat stressed pigs.

The intestinal morphology and function can be compromised in pigs exposed to heat stress (HS), partly due to increased production of reactive-oxygen species. Because methionine (Met) functions as intracellular antioxidant, the requirement of Met may be increased in HS-pigs. The effect of dietary supplementation with dl-Met above requirement on performance, small intestine morphology, antioxidant enzymes activity, amino acid transporters expression, and serum concentration (SC) of free AA in HS-pigs was evaluated. A basal wheat-soybean meal diet was formulated to meet 100% Met requirement with the other indispensable AA exceeding at least 20% their requirement. Sixty individually housed pigs (23.0 ± 2.4 kg BW, 12 pigs per treatment) were randomly assigned to five treatments: TN100, thermal-neutral (22.7 °C) housed pigs fed the basal diet; HS100, HS120, HS140, HS160; HS-pigs (29.6 °C to 39.4 °C) fed the basal diet supplemented with dl-Met to contain 0%, 20%, 40%, and 60% dl-Met above the requirement, respectively. Pigs had free access to feed and water during the 21-d trial. Blood samples were collected on day 18 to analyze the absorptive AA-SC. The effect of ambient temperature (HS100 vs. TN100), as well as the linear and quadratic effects of increasing Met levels in the diets for HS-pigs were analyzed. The HS100 pigs gained less weight than TN100 and HS120 pigs (P < 0.01); gain:feed was also higher in HS120 pigs than in HS100 pigs (P ≤ 0.05). Feed intake of TN100 pigs was higher than that of HS-pigs fed the dl-Met supplemented diets (P < 0.05). Villi height reduced in pigs HS, but Met supplementation quadratically increased it (P < 0.05). Superoxide dismutase and catalase activities, reduced glutathione concentration, and relative expression of B0AT2 in ileum decreased (P < 0.05), but glutathione peroxidase activity increased in HS-pigs. dl-Met supplementation linearly affected catalase and glutathione peroxidase activities, as well as the relative expression of b0,+AT in jejunum (P < 0.05) of HS-pigs. The SC of Ile, Leu, Lys, Phe, and Val were higher in HS100 pigs than in TN100 pigs (P < 0.05). Graded levels of supplemental dl-Met in diets for HS-pigs linearly decreased SC of Ile, Leu, and Val (P < 0.05), tended to decrease His, Lys, and Thr (P < 0.10), and increased Met (P < 0.01). In conclusion, HS had negative effect on weight gain and intestinal morpho-physiology; however, it was ameliorated by adding 20% Met above the requirement in diets for growing pigs.