Plasma Amino Acid Concentrations Research Articles

Risk of gestational diabetes mellitus in relation to plasma concentrations of amino acids and acylcarnitines: A nested case-control study

AimsGestational diabetes mellitus (GDM) affects between 5 and 10% of all pregnancies in Canada and can lead to adverse health outcomes in both the mother and fetus. Amino acids (AA) and acylcarnitines (AC) have been identified as early biomarkers of type 2 diabetes but their usefulness in screening for GDM has yet to be demonstrated. MethodsWe conducted a nested case-control study involving 50 controls and 50 GDM cases diagnosed between the 24th and 28th week of gestation. Heparinized plasma samples were obtained during the first and early second trimester of pregnancy. Case and controls were matched according to date of recruitment, maternal age, gestational age at blood sampling as well as pre-pregnancy body mass index. Eight AA and eight AC were quantified using an ultra-high pressure liquid-chromatography quadrupole time-of-flight mass spectrometry platform. Conditional regression analyses adjusted for matching factors and smoking habits during pregnancy were performed to identify plasma metabolites associated with GDM risk. ResultsOdds ratio (OR) and 95% confidence interval (CI) for the prediction of GDM per one standard deviation increase of AA or AC in plasma levels were 0.25 (0.08–0.79) for butyrylcarnitine, 0.31 (0.12–0.79) for glutamic acid, 2.5 (1.2–5.3) for acetylcarnitine, 2.9 (1.3–6.8) for isobutyrylcarnitine and 5.3 (1.7–17.0) for leucine. These five metabolites were selected by stepwise conditional logistic regression to create a predictive model with an OR of 2.7 (1.5–4.9). ConclusionWhether the identified metabolites can predict the risk of developing GDM requires additional studies in a larger sample of pregnant women.

Exercise Training in Standardbred Horses Alters the Skeletal Muscle Metabolome and Plasma Amino Acid Profile: Implications for the “Athlete's Paradox”

To date equine skeletal muscle metabolism has centered on a limited number of candidate metabolites. As such, there is a dearth of information regarding global changes in skeletal muscle metabolism following exercise training. Thus, the purpose of this study was to determine the effects of exercise training on skeletal muscle metabolism through changes in the skeletal muscle metabolome in healthy, untrained Standardbred horses. In addition, we aimed to determine the extent to which protein metabolism is also altered through changes in the concentrations of plasma amino acids (AA). We hypothesized that training would significantly alter the skeletal muscle metabolome, as well as protein metabolism, as reflected in changes in the plasma AA profile. Eight untrained, Standardbred horses (n=4 mares, n=4 geldings; 3–9 yrs; 485 ± 13 kg, mean ± S.E.) underwent a 12‐week training program that significantly increased VO2 and exercise capacity (p<0.05). Percutaneous needle biopsies were obtained from the M. gluteus medius in the untrained state (UT) and again following training (TR). Frozen muscle samples were submitted to Metabolon, Inc. for global metabolite profiling via UHPLC‐MS/MS. Blood obtained via jugular venipuncture was placed into EDTA tubes for the measurement of plasma AA concentrations via HPLC. For metabolomics analysis, differences between UT and TR samples were evaluated by two way‐ANOVA and Welch's t‐test for paired comparisons and considered significant at p<0.05. For plasma AAs, differences were analyzed via Student's t‐test and considered significant at p<0.05. Training resulted in significant alterations in lipid, branched‐chain amino acid (BCAA), and nucleotide metabolite classes in skeletal muscle. Of note, analysis revealed significant increases in the relative abundance of almost every identified FFA and complex lipid species in TR compared to UT muscle (p<0.05), particularly the long‐chain (LC)‐acylcarnitines and diacylglycerides (DAGs) (1.5 to 2.3‐fold increases). Further, TR muscle exhibited increased fold‐changes (1.2 to 4.2‐fold) of C4 and several C5 BCAA‐derived acylcarnitines compared to UT (p<0.05). In plasma, training caused a significant 36% increase in the concentration of total essential AAs (p<0.05), of which and interestingly there was a significant increase in total BCAAs (42%, p<0.05) and phenylalanine (27%, p<0.05). In conclusion, exercise training significantly increased blood concentrations of total EAAs and BCAAs alongside significant increases in the relative abundances of certain skeletal muscle metabolites (i.e. LC‐acylcarnitines, BCAA‐derived acylcarnitines, and DAGs) that have been shown to be elevated during obesity and are proposed to play a role in the development of insulin resistance. These data underscore the complex nature of static metabolic signatures and the role that certain metabolites play in mediating health and disease. Future research should aim to utilize other sophisticated techniques that can address issues of metabolite flux and tissue utilization.Support or Funding InformationThis research was supported by: the New Jersey Institute for Food, Nutrition and Health (IFNH), USDA NIFA (NC 1184), the Rutgers University Equine Science Center (ESC), and the New Jersey Agriculture Experiment Station (NJAES).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Regulation of Amino Acids in Muscle and Blood from Patients with Pancreatic Cancer‐ Induced Cachexia

Cachexia, or weight loss, is a profound side effect of cancer. Patients that suffer from cachexia have poor treatment tolerance, poor post‐surgical outcomes, poor survival, and poor quality of life. Despite decades of research, we lack a pharmacological intervention to treat cachexia, as mechanisms driving cachexia remain incompletely understood. Further, while the significance of cancer cachexia is clear, this syndrome remains poorly recognized, and a biomarker of cancer cachexia would be a valuable tool to improve the recognition of this syndrome. Because cachexia is ultimately a metabolic syndrome, we hypothesized that a metabolomics approach could identify new potential mechanisms of cachexia while also identifying potential biomarkers. Using a targeted mass spectrometry approach, we sought to distinguish cachectic pancreatic cancer patients from those without cancer or weight stable pancreatic cancer patients. Surprisingly, amino acid content of muscle from both cachectic and weight stable cancer patients was pronouncedly decreased compared to control patients. Similarly, plasma amino acid content was also generally decreased in both weight stable and cachectic cancer patients. Only differential levels of gamma‐amino‐N‐butryic acid (GABA) distinguished cachectic cancer patients from weight stable cancer patients and controls. In summary, the majority of changes we detected were specific to pancreatic cancer rather than cachexia, emphasizing the need to include cancer patients with and without cachexia in the study design.Support or Funding InformationSupport was provided through a Pilot and Feasibility Grant from the Mayo Clinic Metabolomics Resource Core through grant number U24DK100469 from the National Institute of Diabetes and Digestive and Kidney Diseases. Additional funding was provided by NIH R01CA180057 (DCG) and American Cancer Society Postdoctoral Fellowship PF‐15‐156‐01‐CSM (EET).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Plasma Amino Acid Profile in Severely Frail Elderly Patients in Japan

Summary Background Severe frailty, which is the highest level of frailty, leads to multiple health impairments that may individually affect the plasma-free amino acid (PFAA) profile. However, the PFAA profile of severely frail patients has not been clarified. The aim of this study was to describe the PFAA profile of severely frail elderly patients. Methods Elderly patients (aged ≥65 years) who were admitted to the Nukada Institute for Medical and Biological Research (Chiba, Japan) were included. Severe frailty was defined using the Canadian Study of Health and Aging Clinical Frailty Scale. Subjects were divided into non-frail and severely frail groups. The PFAA profile and clinical characteristics of the subjects were analyzed. Results Compared to the non-frail group (n = 31), the severely frail group (n = 28) had lower body mass index (BMI), serum albumin, serum prealbumin, hemoglobin, and blood pressure and higher C-reactive protein. Seventy-nine percent of severely frail patients had cognitive impairment. Severely frail patients had significantly lower essential amino acid (EAA) plasma concentrations than non-frail patients. Multiple linear regression analysis identified that valine (p = 0.005) was strongly associated with BMI. Valine (p = 0.004), leucine (p = 0.004), tryptophan (p = 0.006), lysine (p Conclusion Severely frail patients had multiple health impairments. BMI and nutritional status were most significantly associated with low EAA levels.

Improved uterine immune mediators in Holstein cows supplemented with rumen-protected methionine and discovery of neutrophil extracellular traps (NET)

During the transition from prepartum to early lactation, dairy cows often experience negative energy balance (NEB) that may result in reproductive stress and decreased fertility. The objective of this study was to observe the effects of rumen-protected methionine (RPM) on plasma amino acid concentrations, uterine cytology, immunohistochemistry (IHC) of glutathione peroxidase 1 (GPX) and superoxide dismutase 1 (SOD), and to confirm neutrophil extracellular trap (NET) formation. Multiparous Holstein cows (n = 20) were randomly assigned to two treatments starting at 21 d before calving until 73 days in milk (DIM). Treatments were: CON (n = 9, no supplementation, TMR with a Lys:Met = 3.5:1) and MET (n = 11, TMR + Smartamine® M with a Lys:Met = 2.8:1). Uterine endometrial biopsies, uterine cytology, and blood samples from the coccygeal artery or vein were collected at 15, 30, and 73 DIM. Blood plasma samples were analyzed for amino acids and metabolites. Uterine biopsies were analyzed for NET formation, neutrophil numbers, as well as GPX and SOD by IHC. Additionally, uterine cytology was analyzed for polymorphonuclear neutrophil (PMN) to epithelial cell percentage. Cows in CON had lower methionine plasma concentrations (18.05 ± 2.0 μM) than cows in MET (30.39 ± 1.6 μM). Cows in CON had greater cystine plasma concentrations (3.62 ± 0.3 μM) than cows in MET (2.8 ± 0.3 μM). No treatment differences were observed for SOD or GPX in the endometrium. Cows in CON tended to have a high score for positively immunolabeled GPX cells at 15 DIM than cows in MET. No treatment differences were observed for the percentage of PMN in uterine cytology, number of neutrophils, or extent of NET formation in the endometrium. A treatment by time interaction was observed for PMN percentage and the number of neutrophils: cows in MET tended to have greater PMN percentages than cows in CON at 15 DIM which decreased for subsequent days and cows in MET had greater neutrophil numbers in the endometrium at 30 DIM than cows in CON. In conclusion, dietary supplementation of RPM altered plasma amino acid concentrations and increased neutrophil infiltration in the postpartum period, suggesting improved uterine immunity.

Effects of grain species, genotype and starch quantity on the postprandial plasma amino acid response in horses

Postprandial alterations of plasma amino acid (PAA) levels partly reflect a temporal contribution of the feed. How cereal grains affect PAA levels is not known. We hypothesized that a meal of cereal grains causes a temporal increase of PAA, affected by grain species, grain genotype and meal size. Six mares were used in three consecutive trials, receiving four oats, barley and maize genotypes, respectively. Individual grain genotypes were provided as 3 meal sizes corresponding to 1.0, 1.5 or 2.0 g starch/kg body weight. Meadow hay (1.5 kg/100 kg body weight) was offered daily. At the test days, 1 kg hay was fed 60 min prior to the grain meal. Blood samples were taken before grain feeding (0 min) and 30, 60, 90, 120, 180, 240 and 300 min thereafter. Subsequently, the remaining hay was offered. The genotype × starch quantity (i.e., meal size) interaction had a major effect on postprandial PAA concentrations (P < 0.05). Availability of amino acids (AA), ingested from different grain genotypes, apparently differed at both the digestive and post-digestive level. Thus, AA supply from grain feeding can better be assessed on the genotype level. The concentrations of most PAA increased rapidly with a postprandial maximum at around 30 min. Hay feeding might have an underrated capability for AA provision because increases of PAA levels were initialized already by ingestion of a 1 kg hay. It remains unclear which portion of the PAA kinetics response originates from hay feeding and which one from the cereal grain meal.

Reference Interval for Plasma Free Amino Acids in Iranian Children Using Reverse Phase High Performance Liquid Chromatography

Background: Brain damage and mental retardation in children can be caused by either excess or depletion of certain amino acids. Up to now there is no reliable reference interval for free plasma amino acid in Iranian children. Objectives: The aim of this study was to provide the reference intervals of free plasma amino acid in healthy Iranian children using high performance liquid chromatography (HPLC) as an accurate method. Methods: 133 children referred to Children’s Medical Center, Tehran, Iran for the annual checkup entered the study after filling out the informed consent form. Demographic data and blood samples after overnight fasting were collected. Plasma amino acid concentrations were determined by reverse phase HPLC (RP-HPLC) equipped with a fluorescence detector after precolumn derivatization of amino acids with o-phthalaldehyde (OPA). Results: Female children exhibited significantly higher plasma concentrations of taurine and lysine than male children. Other 20 amino acid values were not significantly different between two gender groups. Positive correlation was obsereved between age and taurine, leucine and lysine. Conclusions: Our data provided reference intervals of free plasma amino acids in healthy Iranian children. We believe our data can be used as a guideline for pediatricians to identify the significantly deviated amino acid values in children with medical issues such as genetic disorders and some acquired illnesses. Our data is also applicable for further investigations in the field of family medicine.

Plasma Amino Acid Concentrations Are Associated with Muscle Function in Older Japanese Women.

Although several previous studies have found benefits for amino acid supplementation in terms of muscle function, the role of plasma amino acid concentrations on sarcopenia are not well addressed yet. The aim of this study was to compare the amino acid concentrations at each stage of sarcopenia (normal, pre-sarcopenia, dynapenia, and sarcopenia) in community-dwelling older Japanese adults. Community-dwelling older Japanese women (n=232, 79.4±7.0 years) participated in this study. We measured plasma amino acid concentrations, 5-m walking speed, grip strength, and skeletal muscle mass using a bioelectrical impedance data acquisition system and compared them among participants at each stage of sarcopenia. The proportions of normal, pre-sarcopenia, dynapenia, and sarcopenia patients were 40.5% (n=94), 12.1% (n=28), 26.3% (n=61), and 21.1% (n=49), respectively. Significant differences were observed for concentrations of leucine, branched-chain amino acid (BCAAs), and essential amino acid (EAAs) among the four groups (p<0.05), and the dynapenia and sarcopenia groups showed significantly lower concentrations of leucine than the normal group (p<0.05). This study indicated a positive relationship between plasma leucine, BCAA and EAA concentrations and muscle function. A longitudinal study is needed to determine the causal relationship between leucine/BCAA concentrations and muscle function.

Impacts of increasing levels of canola meal in diets of high producing Holstein cows on their productive performance

Ingredient substitution studies are common in the animal science literature. However such studies often confound changes of ingredient and nutrient levels, thereby begging the question as to whether responses measured among diets represent known differences among diets in measured nutrient levels, or to changes in unknown dietary factors/nutrients. Our objective was to determine if formulating diets to contain the same levels of nutrients, concomitant with increasing the dietary canola meal (CM) level from 50 to 170 g/kg of diet dry matter (DM), while mainly reducing levels of distillers dried grains (DDG), would result in dissimilar performance by lactating dairy cattle – thereby suggesting nutritional factors/nutrients of CM and/or DDG exist which are not known and so not included in diet formulation. This differs from Swanepoel et al. (2014; Anim. Feed Sci. Technol. 189, 41–53) wherein increasing levels of CM were confounded with modest changes in dietary levels of some proximate nutrients. The experiment was a 4 × 4 Latin square using 4 pens of about 315 early lactation multiparous cows/pen with four 21 day periods. The DM intake was not affected (30.0 ± 0.09 kg/d) by increased dietary levels of CM, but milk, milk lactose and milk energy outputs all declined (P < 0.01) linearly, as did milk somatic cell counts. Change in body condition score (BCS) declined linearly (P < 0.01), with a quadratic component (P < 0.01), suggesting maximum BCS gain at about 80 g/kg CM inclusion. Plasma concentrations of most essential amino acids increased linearly (P < 0.01) with higher dietary levels of CM – exceptions being Met and Phe (unaffected) and Leu (declined). As a result of lower milk energy output and lower accretion of energy in BCS gain, as well as similar DM intake, estimated net energy for lactation (NEl) of the diet declined linearly as inclusion of CM increased. While our objective of creating diets with no changes in dietary nutrient levels and biological measures was mainly met, there was an unexpected linear (P < 0.01) decrease of 6.3 g/kg DM in the crude fat level of the diets concomitant with the increase in CM inclusion. However the calculated decrease of diet NEl as a direct result of this difference in diet crude fat only accounted for about 40% of the decline in the estimated NEl density of the diet (i.e., 0.08 MJ/kg DM of NElversus the actual decline of 0.21 MJ/kg DM of NEl). This suggests that if the diets had achieved equal fat levels, as well as other nutrients, concomitant with increasing levels of CM, that NEl output of the cows would have still declined. Thus diets formulated with 170 g/kg of CM in diet DM (from 50 g/kg DM of CM) in substitution for primarily corn based DDG, but with equal levels of primary nutrients, resulted in a small reduction in performance of lactating dairy cows for reasons which are unknown, but may relate to lower conversion of digestible to metabolizable energy of the soluble carbohydrate fraction of CM versus DDG.

Plasma Amino Acid Concentration in the Hepatic Vein Compared to Peripheral Blood

Introduction Patients with liver disease show abnormalities in the plasma amino acid profile In order to investigate and further advance in the study of protein and amino acid metabolism in liver cirrhosis we studied the amino acid differences between hepatic vein and peripheral blood Methods We studied male adult patients with biopsy proven liver cirrhosis and endoscopic evidence of portal hypertension Patients were fasted for at least hours before the study Hepatic vein samples were obtained from a catheter placed in the hepatic vein and peripheral blood samples were obtained from the femoral vein Results We observed that in most cases there was a lower concentration of the individual amino acids in the hepatic vein compared to those in the peripheral vein but they were not significant except in the case of alanine Conclusion We confirmed the characteristic pattern of increased concentration of the aromatic amino acids AAA and decreased concentration of branched chain amino acids BCAA The general trend towards lesser concentration of amino acids in the hepatic vein compared to peripheral vein observed in this study probably reflects the combined effect of amino acid exchange across the whole splanchnic bed The higher alanine concentration in peripheral blood in this case representing blood coming from muscles seems to be the result of the glucose alanine cycle

An attenuated rate of leg muscle protein depletion and leg free amino acid efflux over time is seen in ICU long-stayers

BackgroundThere is extensive documentation on skeletal muscle protein depletion during the initial phase of critical illness. However, for intensive care unit (ICU) long-stayers, objective data are very limited. In this study, we examined skeletal muscle protein and amino acid turnover in patients with a prolonged ICU stay.MethodsPatients (n = 20) were studied serially every 8–12 days between days 10 and 40 of their ICU stay as long as patients stayed in the ICU. Leg muscle protein turnover was assessed by measurements of phenylalanine kinetics, for which we employed a stable isotope-labeled phenylalanine together with two-pool and three-pool models for calculations, and results were expressed per 100 ml of leg volume. In addition, leg muscle amino acid flux was studied.ResultsThe negative leg muscle protein net balance seen on days 10–20 of the ICU stay disappeared by days 30–40 (p = 0.012). This was attributable mainly to an increase in the de novo protein synthesis rate (p = 0.007). It was accompanied by an attenuated efflux of free amino acids from the leg. Leg muscle protein breakdown rates stayed unaltered (p = 0.48), as did the efflux of 3-methylhistidine. The arterial plasma concentrations of free amino acids did not change over the course of the study.ConclusionsIn critically ill patients with sustained organ failure and in need of a prolonged ICU stay, the initial high rate of skeletal muscle protein depletion was attenuated over time. The distinction between the acute phase and a more prolonged and more stable phase concerning skeletal muscle protein turnover must be considered in study protocols as well as in clinical practice.Trial registrationAustralian New Zealand Trial Registry, ACTRN12616001012460. Retrospectively registered on 1 August 2016.

Association between plasma concentrations of branched-chain amino acids and adipokines in Japanese adults without diabetes

Previous studies have consistently reported an association between circulating levels of branched-chain amino acids (BCAAs) or adipokines and insulin resistance; however, the association between BCAA and adipokine levels remains to be clarified. In this cross-sectional study involving 678 participants (435 men) without diabetes, plasma BCAA (valine, leucine, and isoleucine), adipokine (total and high molecular weight [HMW] adiponectin, leptin, and tumor necrosis factor-α [TNF-α]) concentrations, and an updated homeostasis model assessment of insulin resistance (HOMA2-IR) were measured. The association between the concentrations of total BCAAs and adipokines was adjusted for confounding factors, including body mass index. For the lowest and highest BCAA quartiles, the adjusted geometric mean levels of HMW adiponectin were, respectively, 1.51 and 0.91 μg/mL, in men (P for trend < 0.0001); 3.61 and 2.29 μg/mL, in women (P = 0.0005). The corresponding geometric mean levels for leptin were 1681 and 2620 pg/mL, in men (P = 0.003), and 4270 and 6510 pg/mL, in women (P = 0.003). Those for HOMA2-IR were 0.89 and 1.11, in men (P < 0.0001), and 0.79 and 0.96, in women (P < 0.0001); no significant association was found with TNF-α. These results suggest significant associations between BCAA concentrations and those for adiponectin, leptin and HOMA2-IR in individuals without diabetes.

Amino acid profiles of young adults differ by sex, body mass index and insulin resistance

Background and aimsAn increase in plasma branched-chain amino acids is associated with a higher risk of developing type 2 diabetes and cardiovascular diseases. However, little is known about the basal plasma amino acid concentrations in young adults. Our aim was to determine the plasma amino acid profiles of young adults and to evaluate how these profiles were modified by sex, body mass index (BMI) and insulin resistance (IR). Methods and resultsWe performed a transversal study with 608 Mexican young adults aged 19.9 ± 2.4 years who were applicants to the Universidad Autónoma de San Luis Potosí. The subjects underwent a physical examination and provided a clinical history and a blood sample for biochemical, hormonal and amino acid analyses. The women had higher levels of arginine, aspartate and serine and lower levels of α-aminoadipic acid, cysteine, isoleucine, leucine, methionine, proline, tryptophan, tyrosine, urea and valine than the men. The obese subjects had higher levels of alanine, aspartate, cysteine, ornithine, phenylalanine, proline and tyrosine and lower levels of glycine, ornithine and serine than the normal weight subjects. Subjects with IR (defined as HOMA > 2.5) had higher levels of arginine, alanine, aspartate, isoleucine, leucine, phenylalanine, proline, tyrosine, taurine and valine than the subjects without IR. Furthermore, we identified two main groups in the subjects with obesity and/or IR; one group was composed of amino acids that positively correlated with the clinical, biochemical and hormonal parameters, whereas the second group exhibited negative correlations. ConclusionThis study demonstrates that young adults with obesity or IR have altered amino acid profiles characterized by an increase in alanine, aspartate, proline and tyrosine and a decrease in glycine.

Evidence of a liver-alpha cell axis in humans: hepatic insulin resistance attenuates relationship between fasting plasma glucagon and glucagonotropic amino acids.

The secretion of glucagon is controlled by blood glucose and inappropriate secretion of glucagon contributes to hyperglycaemia in diabetes. Besides its role in glucose regulation, glucagon regulates amino acid metabolism in hepatocytes by increasing ureagenesis. Disruption of this mechanism causes hyperaminoacidaemia, which in turn increases glucagon secretion. We hypothesised that hepatic insulin resistance (secondary to hepatic steatosis) via defective glucagon signalling/glucagon resistance would lead to impaired ureagenesis and, hence, increased plasma concentrations of glucagonotropic amino acids and, subsequently, glucagon. To examine the association between glucagon and amino acids, and to explore whether this relationship was modified by hepatic insulin resistance, we studied a well-characterised cohort of 1408 individuals with normal and impaired glucose regulation. In this cohort, we have previously reported insulin resistance to be accompanied by increased plasma concentrations of glucagon. We now measure plasma levels of amino acids in the same cohort. HOMA-IR was calculated as a marker of hepatic insulin resistance. Fasting levels of glucagonotropic amino acids and glucagon were significantly and inversely associated in linear regression models (persisting after adjustment for age, sex and BMI). Increasing levels of hepatic, but not peripheral insulin resistance (p > 0.166) attenuated the association between glucagon and circulating levels of alanine, glutamine and tyrosine, and was significantly associated with hyperaminoacidaemia and hyperglucagonaemia. A doubling of the calculated glucagon-alanine index was significantly associated with a 30% increase in hepatic insulin resistance, a 7% increase in plasma alanine aminotransferase levels, and a 14% increase in plasma γ-glutamyltransferase levels. This cross-sectional study supports the existence of a liver-alpha cell axis in humans: glucagon regulates plasma levels of amino acids, which in turn feedback to regulate the secretion of glucagon. With hepatic insulin resistance, reflecting hepatic steatosis, the feedback cycle is disrupted, leading to hyperaminoacidaemia and hyperglucagonaemia. The glucagon-alanine index is suggested as a relevant marker for hepatic glucagon signalling.

Dietary starch influences growth performance, nutrient utilisation and digestive dynamics of protein and amino acids in broiler chickens offered low-protein diets

A total of 288 day-old, male Ross 308 chicks were offered six dietary treatments from 7 to 28 days post-hatch. A standard maize-soy diet was compared with five low protein diets containing high inclusions of maize starch and various combinations of supplemental amino acids. The assessed parameters included growth performance, nutrient utilisation, digestibility coefficients and disappearance rates of starch, protein and amino acids in four small intestinal segments. Also, the effects of three dietary treatments on free plasma amino acid concentrations in the anterior mesenteric vein or portal circulation were determined. The transition from standard to low protein diets elevated feed intakes and compromised FCR. Overall, tangible differences in responses were not observed in birds offered the five low protein diets which effectively precluded meaningful comparisons between the various combinations of crystalline amino acids. Maize starch inclusions in low protein diets enhanced starch digestibility coefficients and disappearance rates and parameters of nutrient utilisation. However, maize starch also depressed protein digestibility coefficients and disappearance rates. Moreover, amino acid digestibility coefficients were depressed in the three posterior segments of the small intestine. Instructively, proximal ileal starch digestibility coefficients were negatively correlated with digestibility coefficients of twelve amino acids in the proximal ileum to significant extents. Significant differences in concentrations of free amino acids in plasma from the anterior mesenteric vein were observed for histidine, lysine, methionine, threonine and valine in birds offered the standard and two low protein diets. The possibility that glucose and amino acids were effectively competing for intestinal uptakes, especially from the ileum, is discussed. Also, it appears that the metabolic fates of amino acids in enterocytes of the gut mucosa can be manipulated by dietary strategies and that crystalline amino acids may be less prone to undergo catabolism in the gut mucosa.

Innate immunity and metabolomic responses in dairy cows challenged intramammarily with lipopolysaccharide after subacute ruminal acidosis

Subacute ruminal acidosis (SARA) is a prevalent metabolic disorder in dairy cows known to elicit local and systemic immune responses. We recently showed that cows experiencing SARA and challenged intramammarily with lipopolysaccharide (LPS) experienced stronger metabolic disturbances compared with cows without SARA. Therefore, we hypothesized that cows experiencing SARA have a modulated innate immune response and impaired plasma metabolome compared with healthy cows when experiencing an acute mastitis challenge. A total of 18 Simmental cows were subjected either to a Control (CON, n=6) or SARA (n=12) feeding regimen, receiving either 40% or 60% concentrates for 30 days. Thereafter, six SARA (SARA-LPS) and the CON (CON-LPS) cows were intramammarily challenged with 50 µg LPS from Escherichia coli (O26 : B6), while the remaining six SARA cows (SARA-PLA) received a placebo. Blood and milk samples were analyzed for acute phase proteins and a targeted ESI-LC-MS/MS-based metabolomics approach was performed in blood samples 24 h after the LPS challenge. The LPS infusion caused a strong increase in immune response variables, with a higher concentration of milk amyloid A 48 h after the LPS challenge in SARA-LPS compared with CON-LPS cows. Cows receiving the LPS infusion had a lower plasma concentration of several amino acids and lysophosphatidylcholines but without differences in SARA cows and healthy cows. In conclusion, our results revealed that an intramammary LPS infusion increased acute phase proteins and modulated the blood metabolome. While no systemic differences between SARA and healthy cows were observed, cows experiencing SARA showed a higher concentration of an acute phase protein at the local level of the mammary gland. Further research is required to elucidate the underlying mechanisms and to evaluate its clinical significance for udder health.

Homeostatic regulation of plasma amino acid concentrations.

One major goal of nutrition is to maximize the rate of muscle protein gain via provision of amino acids (AAs) through blood plasma. Comparing the plasma AA concentrations with the growth performance data can help to elucidate the metabolic mechanisms regulating plasma AA homeostasis, nutrient utilization, and intracellular protein turnover. Knowledge about the homeostatic regulation of plasma AA profile can aid in predicting dietary AA availabilities, the order of limiting AAs, and the whole body protein metabolism. Lysine, for example, is typically the first limiting AA in practical swine diets; however, our current knowledge is insufficient to draw a clear conclusion about the complex relationship between dietary lysine supply and plasma AA profiles. Thorough understanding of the effect of dietary AA supply on plasma AA profiles can help nutritionists to develop novel nutritional strategies to guide and improve dietary AA supplies. Further research is needed to study how different levels of dietary AAs, individually or in concert, affect the plasma concentrations of all AAs and related metabolites.

Estimation of dietary threonine requirement using plasma amino acid concentrations in mature thoroughbreds.

The experiment was conducted to estimate dietary threonine (Thr) requirement using plasma amino acid concentrations as a criterion in mature thoroughbreds. Four adult thoroughbreds were used, and a 4×4 Latin square design was used for four dietary Thr levels. Plasma Thr concentration was constant until 0.41%, and then increased rapidly with increasing dietary Thr levels. The Thr requirement was estimated to be 67% of lysine with plasma Thr concentration at four Thr levels.

A 48-Hour Vegan Diet Challenge in Healthy Women and Men Induces a BRANCH-Chain Amino Acid Related, Health Associated, Metabolic Signature.

Research is limited on diet challenges to improve health. A short-term, vegan protein diet regimen nutritionally balanced in macronutrient composition compared to an omnivorous diet is hypothesized to improve metabolic measurements of blood sugar regulation, blood lipids, and amino acid metabolism. This randomized, cross-over, controlled vegan versus animal diet challenge is conducted on 21 (11 female,10 male) healthy participants. Fasting plasma is measured during a 3d diet intervention for clinical biochemistry and metabonomics. Intervention diet plans meet individual caloric needs. Meals are provided and supervised. Diet compliance is monitored. The vegan diet lowers triglycerides, insulin and homeostatic model assessment (HOMA-IR), bile acids, elevated magnesium levels, and changed branched-chain amino acids (BCAAs) metabolism (p<0.05), potentiating insulin and blood sugar control after 48 h. Cholesterol control improves significantly in the vegan versus omnivorous diets. Plasma amino acid and magnesium concentrations positively correlate with dietary amino acids. Polyunsaturated fatty acids and dietary fiber inversely correlate with insulin, HOMA-IR, and triglycerides. Nutritional biochemistries, BCAAs, insulin, and HOMA-IR are impacted by sexual dimorphism. A health-promoting, BCAA-associated metabolic signature is produced from a short-term, healthy, controlled, vegan diet challenge when compared with a healthy, controlled, omnivorous diet.

Decreased plasma amino acid concentrations in cats with chronic gastrointestinal diseases and their possible contribution in the inflammatory response

In humans, plasma amino acids (AAs) levels are used as dynamic nutritional markers. Moreover, some AAs are associated with chronic inflammation. In this study, we analyzed plasma AA profiles in cats with chronic gastrointestinal (GI) diseases. Eight healthy controls (HCs) and 12 client-owned cats with chronic GI diseases including chronic enteritis (n=8) and neoplasms (n=4) were recruited. Plasma albumin, total protein, and 22 AAs (11 essential and 11 non-essential AAs) levels were estimated. There was no significant difference in plasma albumin and total protein concentrations between the cats with chronic GI diseases and HCs. The plasma concentrations of 7 essential AAs (arginine, histidine, lysine, methionine, phenylalanine, taurine, and tryptophan) and 7 non-essential AAs (asparagine, aspartic acid, glutamic acid, glycine, hydroxyproline, proline, and serine) were significantly decreased in the cats with chronic GI diseases (P<0.05). Moreover, plasma histidine and tryptophan levels were inversely correlated with severity of symptoms (histidine: rs=−0.7781, P<0.005; tryptophan: rs=−0.6040, P<0.05). To examine the contribution of altered AAs levels in the inflammatory response, feline macrophages were stimulated by lipopolysaccharides (LPS) with or without histidine, and the expression of interleukin-8 (IL-8) mRNA was quantified. The expression of IL-8 mRNA was significantly increased in the LPS-stimulated feline macrophages (P<0.05). Histidine almost suppressed the LPS-induced IL-8 expression in the feline macrophages (P<0.05). Our findings suggest that plasma AAs levels are more sensitive nutritional markers than albumin and total protein levels in cats with chronic GI diseases. There is a possibility that the decrease of histidine levels in cats with GI diseases is associated with chronic inflammation.