Carnosine Levels Research Articles

Untargeted LC-MS metabolomics reveals the metabolic responses in olive flounder subjected to hirame rhabdovirus infection.

Hirame novirhabdovirus (HIRRV), which mainly infects the olive flounder (Paralichthys olivaceus), is considered to be one of the most serious viral pathogens threatening the global fish culture industry. However, little is known about the mechanism of host-pathogen interactions at the metabolomic level. In this study, in order to explore the metabolic response of olive flounder to HIRRV infection, liquid chromatography mass spectrometry (LC-MS) was used to detect the changes of endogenous compounds of the olive flounder after HIRRV infection. A total of 954 unique masses were obtained, including 495 metabolites and 459 lipids. Among them, 7 and 173 qualified differential metabolites were identified at 2 days and 7 days post-infection, respectively. Distinct metabolic profiles were observed along with viral infection. At the early stage of infection, only a few metabolites were perturbed. Among them, the level of inosine and carnosine were increased and the potential antiviral ability of these two metabolites was further confirmed by exogenous addition experiment. At the late stage of HIRRV infection, the metabolic profiles changed remarkably. The changes in amino acids and nucleotides especially the 7-methylguanine also accelerated the amplification of viral particles. And the down-regulation of glutathione (GSH) implied an elevated level of ROS (reactive oxygen species) that attenuated the immune system of flounders. HIRRV also induced the accumulation of purine and reduction of pyrimidine, and elevated LPC and LPE levels. The unbalanced purine/pyrimidine and altered lipid profile may be beneficial for the replication and infection of HIRRV at the late stage of infection. These findings provide new insights into the pathogenic mechanism of HIRRV infection in olive flounder.

Association of Carnosinase-1 Gene Polymorphism with Serum Carnosine and Carnosinease-1 Isoform Levels in Type 2 Diabetics with Cardiovascular Diseases in Iraq

Background: Genetic variations in the carnosinase-1 gene, which may also be associated with cardiovascular issues and result in a higher serum carnosinease-1 level, may affect the levels of carnosine and carnosine synthase in diabetes patients. Objective: To examine the impact of the Carnosineas-1 gene polymorphism SNP (rs 2887) on blood levels of carnosine and carnosine synthase-1 and their relationship to CVD in diabetes. Method: The serum concentrations of carnosine and carnosineas-1 were determined using ELISA-specific kits. The carnosineas-1 gene (CN1) was subjected to the high-resolution melt technique (HRM) with the purpose of identifying gene polymorphisms. Results: Carnosinase-1 levels were considerably raised in the T2DM with CVD group, but serum carnosine levels were significantly higher in both groups. SNPs had little impact on serum carnosine levels, whereas polymorphisms had a big impact on carnosinase-1 levels. Conclusion: By raising serum levels of carnosenease-1, which in turn increases carnosine breakdown, the SNP (rs2887) of the carnosinase-1 gene contributes indirectly to the development of CVD in T2DM.

#4598 ADMINISTRATION OF ASTRAGALUS MEMBRANACEUS IMPROVES RENAL CONDITIONS AND SERUM CARNOSINE LEVELS IN AN ACUTE KIDNEY INJURY MODEL

Abstract Background and Aims Astragalus membranaceus (AM) exhibits various pharmacological effects against many diseases, including chronic kidney disease (CKD) (see http://nccih.nih.gov/health/astragalus). Acute kidney injury (AKI) is a sudden episode of kidney failure. AKI occurs frequently but is believed to heal completely and is likely an important factor causing CKD pathogenesis or progression. Previously, we demonstrated the lethal dose in old mice is 20 mg/kg cis-diamminedichloroplatinum (CDDP), and the dosage that will cause AKI in young mice is 14 mg/kg of CDDP. Low doses of CDDP caused AKI in old mice. However, the same dosage in young mice would manifest AKI that was subsequently completely reversible. On administration of AM, old mice (50 mg/kg) showed significantly improved AKI pathology, suggesting the therapeutic effect of AM is age-dependent with regard to AKI pathogenicity. Here, we further examined the possible effect of AM in preventing AKI and delaying CKD progression. Method Female C57BL/6 mice were separated into three groups based on age: young, 10 weeks; middle-aged, 35 weeks; and old, 52 weeks. The mice received oral administered of either AM powder mixed with sterilized 0.5% methylcellulose 400 (w/v) (AM group) or 0.5% methylcellulose 400 alone in the control group (CG). Four hours after most recent dose (twice a day at 20 mg/kg AM), 0.5 mg/ml CDDP (reduced dose: 14 mg/kg or 0.9% NaCl for the CG) was injected intraperitoneally. We measured blood serum urea nitrogen (BUN) and creatinine (CRE) levels, which are biomarkers of AKI. Additionally, we assessed histochemical changes in kidney sections stained with anti-CD3 and anti-CD68 antibodies after the mice were sacrificed on day x. Thereafter, serum carnosine levels in the samples collected 4 hours after AM administration (n = 6 per group) were determined using a carnosine ELISA kit (Novus, NBP2-75013). Data were analyzed statistically with PRISM software. Significance was considered P = 0.05. Results The 14 mg/kg CDDP dose in old mice significantly increased BUN and CRE levels and caused histological damage in renal tubule epithelial cells and glomeruli. However, these pathological changes were not observed in young and middle-aged mice receiving the same CDDP dose. Histochemical analysis of the old mice showed a significant increase in the number of CD3- and CD68-positive cells following AKI induction (Fig. 1). However, the increase of these inflammatory markers was clearly ameliorated by the AM pretreatment in the experimental group. Serum carnosine levels were markedly increased in young and middle-aged mice following AM administration (Fig. 2). Moreover, the serum carnosine concentration in old mice was upregulated at levels corresponding to those in young mice with AM administration. However, serum carnosine levels showed no additional increase after AM administration in old mice and remained stable. Our findings suggest that normal renal conditions show a simple upregulation of serum carnosine level after AM administration. Furthermore, AM administration improves renal conditions in old mice with high levels of CD-3 positive cells in particular (Fig. 1, arrow). Figure 2 shows the increased and then subsequent stabilizing of the serum carnosine levels (Fig. 2, arrow). Conclusion AM administration can upregulate serum carnosine in younger mice and shows at least some effectiveness in older mice, where serum carnosine is downregulated but concentrated. Serum carnosine might not be necessary for reducing the pathogenesis of AKI in younger mice, but it becomes important to prevent AKI in old mice. This indicates the effect of AM is probably age-dependent because AKI sequelae manifested spontaneously in all mice but were specifically ameliorated when administered to old mice as opposed to younger mice who recovered completely irrespective of AM administration.

Skeletal muscle analysis of cancer patients reveals a potential role for carnosine in muscle wasting.

Muscle wasting during cancer cachexia is mediated by protein degradation via autophagy and ubiquitin-linked proteolysis. These processes are sensitive to changes in intracellular pH ([pH]i ) and reactive oxygen species, which in skeletal muscle are partly regulated by histidyl dipeptides, such as carnosine. These dipeptides, synthesized by the enzyme carnosine synthase (CARNS), remove lipid peroxidation-derived aldehydes, and buffer [pH]i . Nevertheless, their role in muscle wasting has not been studied. Histidyl dipeptides in the rectus abdominis (RA) muscle and red blood cells (RBCs) of male and female controls (n=37), weight stable (WS: n=35), and weight losing (WL; n=30) upper gastrointestinal cancer (UGIC) patients, were profiled by LC-MS/MS. Expression of enzymes and amino acid transporters, involved in carnosine homeostasis, was measured by Western blotting and RT-PCR. Skeletal muscle myotubes were treated with Lewis lung carcinoma conditioned medium (LLC CM), and β-alanine to study the effects of enhancing carnosine production on muscle wasting. Carnosine was the predominant dipeptide present in the RA muscle. In controls, carnosine levels were higher in men (7.87±1.98nmol/mg tissue) compared with women (4.73±1.26nmol/mg tissue; P=0.002). In men, carnosine was significantly reduced in both the WS (5.92±2.04nmol/mg tissue, P=0.009) and WL (6.15±1.90nmol/mg tissue; P=0.030) UGIC patients, compared with controls. In women, carnosine was decreased in the WL UGIC (3.42±1.33nmol/mg tissue; P=0.050), compared with WS UGIC patients (4.58±1.57nmol/mg tissue), and controls (P=0.025). Carnosine was significantly reduced in the combined WL UGIC patients (5.12±2.15nmol/mg tissue) compared with controls (6.21±2.24nmol/mg tissue; P=0.045). Carnosine was also significantly reduced in the RBCs of WL UGIC patients (0.32±0.24pmol/mg protein), compared with controls (0.49±0.31pmol/mg protein, P=0.037) and WS UGIC patients (0.51±0.40pmol/mg protein, P=0.042). Depletion of carnosine diminished the aldehyde-removing ability in the muscle of WL UGIC patients. Carnosine levels were positively associated with decreases in skeletal muscle index in the WL UGIC patients. CARNS expression was decreased in the muscle of WL UGIC patients and myotubes treated with LLC-CM. Treatment with β-alanine, a carnosine precursor, enhanced endogenous carnosine production and decreased ubiquitin-linked protein degradation in LLC-CM treated myotubes. Depletion of carnosine could contribute to muscle wasting in cancer patients by lowering the aldehyde quenching abilities. Synthesis of carnosine by CARNS in myotubes is particularly affected by tumour derived factors and could contribute to carnosine depletion in WL UGIC patients. Increasing carnosine in skeletal muscle may be an effective therapeutic intervention to prevent muscle wasting in cancer patients.

Effect of muscle fibre types and carnosine levels on the expression of carnosine-related genes in pig skeletal muscle

It is generally accepted that carnosine (β-alanyl-l-histidine) content is higher in glycolytic than in oxidative muscle fibres, but the underlying mechanisms responsible for this difference remain to be elucidated. A first study to better understand potential mechanisms involved was undertaken (1) to determine whether differences in the expression of carnosine-related enzymes (CARNS1, CNDP2) and transporters (SLC6A6, SLC15A3, SLC15A4, SLC36A1) exist between oxidative and glycolytic myofibres and (2) to study the effect of carnosine on myoblast proliferative growth and on carnosine-related gene expression in cultured myoblasts isolated from glycolytic and oxidative muscles. Immunohistochemistry analyses were conducted to determine the cellular localization of carnosine-related proteins. Laser-capture microdissection and qPCR analyses were performed to measure the expression of carnosine-related genes in different myofibres isolated from the longissimus dorsi muscle of ten crossbred pigs. Myogenic cells originating from glycolytic and oxidative muscles were cultured to assess the effect of carnosine (0, 10, 25 and 50 mM) on their proliferative growth and on carnosine-related gene expression. The mRNA abundance of CNDP2 and of the studied carnosine transporters was higher in oxidative than in glycolytic myofibres. Since carnosine synthase (CARNS1) mRNA abundance was not affected by either the fibre type or the addition of carnosine to myoblasts, its transcriptional regulation would not be the main process by which carnosine content differences are determined in oxidative and glycolytic muscles. The addition of carnosine to myoblasts leading to a dose-dependent increase in SLC15A3 transcripts, however, suggests a role for this transporter in carnosine uptake and/or efflux to maintain cellular homeostasis.

Effect of lupin flake supplementation on rumen fermentation and meat composition of Hanwoo steers

Lupin is considered a potentially rich source of energy and protein for various livestock breeds. However, there are no studies on rumen fermentation and meat composition of Hanwoo (Korean native) steers following supplementation with lupin flakes. In vitro and in situ experiments of lupin flake-supplemented feed were conducted using three Hanwoo cows with rumen fistulae for four weeks. The feeding experiment was conducted using 40 early-fattening Hanwoo steers randomly divided into four groups for 14 months from 16 to 30 months of age, viz., T1, T2, T3, and T4, with feed containing 0%, 3%, 6%, and 9% lupin flakes, respectively. The pH of the ruminal fluid in vitro at 24 and 48 h was higher in T3 and T4 than T1. The rumen levels of acetate, propionate, butyrate, and total volatile fatty acids after 48 h of incubation were lower in the lupin-supplemented groups than in T1. The ruminal pH in situ after 9 and 12 h was higher in T3 than in T1. The strip loin in Hanwoo steers was lighter in T3 than in the other treatment groups. The levels of carnosine, creatinine, adenosine triphosphate, and adenosine monophosphate in the strip loin were higher in T3 and T4 than in T1. The levels of oleic acid and unsaturated fatty acids and the n-6/n-3 ratio tended to be higher in T3 than in T1. Supplementation of livestock feed with 6% lupin flakes had positive effects on ruminal pH and meat lightness, carnosine, creatinine, adenosine triphosphate, and adenosine monophosphate levels in Hanwoo beef.

Integrative transcriptomic and metabolomic analysis reveals alterations in energy metabolism and mitochondrial functionality in broiler chickens with wooden breast

This integrative study of transcriptomics and metabolomics aimed to improve our understanding of Wooden Breast myopathy (WB). Breast muscle samples from 8 WB affected and 8 unaffected male broiler chickens of 47 days of age were harvested for metabolite profiling. Among these 16 samples, 5 affected and 6 unaffected also underwent gene expression profiling. The Joint Pathway Analysis was applied on 119 metabolites and 3444 genes exhibiting differential abundance or expression between WB affected and unaffected chickens. Mitochondrial dysfunctions in WB was suggested by higher levels of monoacylglycerols and down-regulated genes involved in lipid production, fatty acid beta oxidation, and oxidative phosphorylation. Lower levels of carnosine and anserine, along with down-regulated carnosine synthase 1 suggested decreased carnosine synthesis and hence impaired antioxidant capacity in WB. Additionally, Weighted Gene Co-expression Network Analysis results indicated that abundance of inosine monophosphate, significantly lower in WB muscle, was correlated with mRNA expression levels of numerous genes related to focal adhesion, extracellular matrix and intercellular signaling, implying its function in connecting and possibly regulating multiple key biological pathways. Overall, this study showed not only the consistency between transcript and metabolite profiles, but also the potential in gaining further insights from analyzing multi-omics data.

Nutrition and Equine Performance

Some aspects of energy, protein and vitamin E nutrition of the performance horse are discussed. The amount, dietary source and time of ingestion of energy before exercise can influence performance. In 1989 the National Research Council (NRC) increased their estimates of energy required by racehorses. Recent studies indicate that the increase was reasonable. Many factors, however, can influence energy requirements. Therefore, the best measure would be body weight and composition of the horse. A proper balance of soluble carbohydrate, fiber, fat and protein is essential. Some guidelines are presented. The amount and type energy source given before exercise can influence level of plasma glucose and free fatty acids during exercise, but the effects of these changes in the concentration of metabolites remains to be determined. There is no evidence that increased dietary concentrations of protein are needed and, in fact, may impair performance. Supplemental histidine (to enhance carnosine levels) or carnitine appear to be of limited value for horses fed conventional diets. Dietary concentrations of vitamin E less than the 80 IU/kg recommended by NRC seem to adequately protect against exercise-induced peroxidation. The NRC value may be justified on the basis of immune response, but further studies are needed. Vitamin E has been shown to be involved with familial equine degenerative myeloencephalopathy and may be involved with equine motor neuron disease, a condition considered to be similar to amyotrophic lateral sclerosis in humans.

Exploring the structural and dynamic differences between human carnosinase I (CN1) and II (CN2).

Human carnosinases (CNs) are dimeric dipeptidases in the metallopeptidase M20 family. Two isoforms of carnosinases (Zn2+ -containing carnosinase 1 (CN1) found in serum and Mn2+ -carnosinase 2 (CN2) in tissue) were identified. Both CNs cleave histidine-containing (Xaa-His) dipeptides such as carnosine where CN2 was found to accept a broader spectrum of substrates. A loss of CN function, resulting in a high carnosine concentration, reduces risk for diabetes and neurological disorders. Although several studies on CN activities and its Michaelis complex were conducted, all shed the light on CN1 activity where the CN2 data is limited. Also, the molecular details on CN1 and CN2 similarity and dissimilarity in structure and function remain unclear. Thus, in this work, molecular dynamics (MD) simulations were employed to study structure and dynamics of human CN1 and CN2 in comparison. The results show that the different catalytic ability of both CNs is due to their pocket size and environment. CN2 can accept a wider range of substrate due to the wider mouth of a binding pocket. The L1 loop seems to play a role in gating activity. Comparing to CN2, CN1 provides more electronegative entrance, more wettability, and higher stability of catalytic metal ion-pair in the active site which allow more efficient water-mediated catalysis. The microscopic understanding obtained here can serve as a basis for CN inhibition strategies resulting in higher carnosine levels and consequently mitigating complications associated with diseases such as diabetes and neurological disorder.

The Influence of β-Alanine Supplementation on Recovery Biomarkers in Adults: A Systematic Review and Meta-Analysis

Background: Clinical studies, investigating the effect of β-Alanine (BA) supplementation on recovery biomarkers in physically active individuals, have generated inconsistent results. This systematic review and meta-analysis study aimed to clarify the clinically relevant dietary effects of BA supplementation. Methods: A comprehensive search was done in the electronic databases of Scopus, PubMed, ISI Web of Science and Embase from inception to 2022. Meta-analysis was done using the random-effects model. Pooled effect size was evaluated using standard mean difference (SMD) and 95% confidence intervals (CI). Heterogeneity of between-study was evaluated according to Cochran’s Q test and I2 . Subgroup analysis was conducted to identify the potential sources of heterogeneity. Results: Overall, 32 studies were included in the current study. The results suggested that BA supplementation increases carnosine level significantly (SMD: 0.22mmol/L, 95%CI: -0.17, 0.61, P=0.27) but no effect was shown about lactate, fatigue, VO2 , pH and bicarbonate (HCO3 - ) (P>0.05). Subgroup analysis revealed a significant association of VO2, carnosine and fatigue with supplementation dosage, gender and duration of administration respectively. Conclusion: BA supplementation emerged its beneficial effects on enhancing carnosine level which highlights its ergogenic effects. In contrast, no significant effects had been shown in term of fatigue delay and blood levels of lactate, HCO3 - , pH, and VO2 value. These results warrant more investigation in a prospective design to clarify the exact mechanism in this way.

Serum levels of carnosine may be associated with the duration of MDD episodes

BackgroundMajor depressive disorder (MDD) is a recurrent disorder that incurs a high societal burden. However, the etiology of MDD remains unclear. The functioning of several systems associated with the etiopathogenesis of MDD, such as inflammatory and stress systems, is partially modulated by the dipeptide carnosine. MethodsThe study comprised 99 MDD patients and 253 non-depressed controls aged 20–71 years. Fasting serum samples were analyzed using ultra-performance liquid chromatography coupled to mass spectrometry to determine the serum levels of carnosine and its constituent, histidine. We compared these metabolites in three different settings: 1) MDD patients vs. non-depressed controls and 2) remitted vs. non-remitted MDD patients, as well as 3) changes in the metabolite levels during the follow-up period within a) the remitted group and b) the non-remitted group. In addition, we assessed the possible effect of medications on the measured metabolites. ResultsWe observed higher serum levels of carnosine in the MDD group compared to the control group at baseline (OR = 1.895, 95%CI = 1.223–2.937, p = 0.004). Elevated serum levels of carnosine were also associated with a longer duration of the depressive episode (Z = 0.406, p = 0.001). However, the use of any antipsychotic medication (n = 36) was associated with lowered carnosine levels (p = 0.010 for use vs. non-use). At the follow-up, remitted and non-remitted participants displayed no significant differences in their carnosine levels (Z = -0.14, p = 0.891) or histidine (Z = −1.39 p = 0.164). ConclusionsAn increase in circulating carnosine may characterize depressive episodes and may represent a protective homeostatic reaction against MDD-related oxidative stress and inflammation.

Using 2D qNMR analysis to distinguish between frozen and frozen/thawed chicken meat and evaluate freshness

We identified key metabolites reflecting microbial spoilage and differentiated unfrozen meat from frozen/thawed (FT) using 2D qNMR analysis. Unfrozen and FT chicken breasts were prepared, individually aerobically packaged, and stored for 16 days at 2 °C. Only volatile basic nitrogen (VBN) was significantly changed after 6 log CFU/g of total aerobic bacteria (p < 0.05). Extended storage resulted in an increase in organic acids, free amino acids, biogenic amines, and hypoxanthine and a decrease in N,N-dimethylglycine, inosine 5′-monophosphate, and proline. Acetic acid demonstrated the highest correlation with VBN (r = 0.97). Unfrozen and FT breast meat can be differentiated by uniform concentration of carnosine, β-alanine, and histidine levels, consistent changes in nucleotides by storage time, and changes in microbial metabolism patterns that are reflected by some free amino acids. Thus, NMR-based metabolomics can be used to evaluate chicken breast meat freshness and distinguish between unfrozen and FT meat.

Anti-Inflammatory Diet Prevents Subclinical Colonic Inflammation and Alters Metabolomic Profile of Ulcerative Colitis Patients in Clinical Remission.

A relationship between ulcerative colitis (UC) and diet has been shown in epidemiological and experimental studies. In a 6-month, open-label, randomized, placebo-controlled trial, adult UC patients in clinical remission were randomized to either an “Anti-inflammatory Diet (AID)” or “Canada’s Food Guide (CFG)”. Menu plans in the AID were designed to increase the dietary intake of dietary fiber, probiotics, antioxidants, and omega-3 fatty acids and to decrease the intake of red meat, processed meat, and added sugar. Stool was collected for fecal calprotectin (FCP) and microbial analysis. Metabolomic analysis was performed on urine, serum, and stool samples at the baseline and study endpoint. In this study, 53 patients were randomized. Five (19.2%) patients in the AID and 8 (29.6%) patients in the CFG experienced a clinical relapse. The subclinical response to the intervention (defined as FCP < 150 µg/g at the endpoint) was significantly higher in the AID group (69.2 vs. 37.0%, p = 0.02). The patients in the AID group had an increased intake of zinc, phosphorus, selenium, yogurt, and seafood versus the control group. Adherence to the AID was associated with significant changes in the metabolome, with decreased fecal acetone and xanthine levels along with increased fecal taurine and urinary carnosine and p-hydroxybenzoic acid levels. The AID subjects also had increases in fecal Bifidobacteriaceae, Lachnospiraceae, and Ruminococcaceae. In this study, we found thatdietary modifications involving the increased intake of anti-inflammatory foods combined with a decreased intake of pro-inflammatory foods were associated with metabolic and microbial changes in UC patients in clinical remission and were effective in preventing subclinical inflammation.

Assessment of chicken thigh meat quality of Ross 308 broiler of animal welfare certified farm

This study aimed to evaluate the difference in the thigh meat quality of Ross 308 broiler from conventional and welfare farms. Thigh meat samples of Ross 308 broilers (age, 35 d; carcass weight, 1.1 kg) from conventional farm (RCF, n = 60) and animal welfare farms (RAWF, n = 60) were analyzed. Proximate composition, pH, color (lightness, redness, and yellowness), water-holding capacity (WHC), shear force, total aerobic bacteria (TAB), and volatile basic nitrogen (VBN) were measured and the levels of bioactive compounds such as dipeptides (anserine and carnosine), creatine, creatinine, and their anti-oxidation activity were determined. The RCF and RAWF did not differ significantly in their proximate composition, WHC, color, and creatine and carnosine levels. The pH value was significantly lower in RAWF than in RCF on day 7. The shear force value was significantly higher in RAWF than in RCF throughout the storage duration. TAB in RCF on day 9 were significantly higher than those in RAWF. The VBN content of RAWF was significantly lower than that of RCF after 5 days of storage. Creatinine content was significantly higher in RAWF (3.50 mg/100 g) than in RCF (3.08 mg/100 g) on day 1. Along with higher carnosine and anserine contents of RAWF, it had significantly higher 2,2-diphenyl-1-picrylhydrazyl and 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) radical scavenging activities than those of RCF. These results imply that the animal welfare farming system beneficially affects the overall oxidative stability of Ross 308 thigh meat.

Multi-Omics Approaches Revealed the Associations of Host Metabolism and Gut Microbiome With Phylogeny and Environmental Adaptation in Mountain Dragons

The molecular basis enabling the adaptation of animals to spatially heterogeneous environments is a critical clue for understanding the variation, formation, and maintenance of biodiversity in the context of global climate change. Mountain dragons (Agamidae: Diploderma) thrive in the Hengduan Mountain Region, a biodiversity hotspot and a typical spatially heterogeneous environment. Here, we compare the liver and muscle metabolome and gut microbiome of 11 geographical populations from three Diploderma species (D. iadinum, D. yulongsense, and D. vela) after 7 days acclimation in the same laboratory conditions. Amino acid metabolism, particularly the products of the glutathione cycle, accounted for major interspecies variations, implying its significance in genetic differentiation among mountain dragons. Notably, the cold-dwelling D. vela and D. yulongense populations tended to have higher glycerophosphate, glycerol-3-phosphocholine, and kinetin levels in their liver, higher carnosine levels in their muscle, and higher Lachnospiraceae levels in their gut. Phylogeny, net primary productivity (NPP), and the temperature had the highest explanation rate to the variations in muscle metabolome, liver metabolome, and gut microbiome, respectively, suggesting heterogeneity of biological systems in response to climatic variations. Therefore, we suggested that the organ heterogeneity in environmental responsiveness might be substantial for mountain dragons to thrive in complicated environments.

Administration of Phosphonate Inhibitors of Dehydrogenases of 2-Oxoglutarate and 2-Oxoadipate to Rats Elicits Target-Specific Metabolic and Physiological Responses.

In vitro and in cell cultures, succinyl phosphonate (SP) and adipoyl phosphonate (AP) selectively target dehydrogenases of 2-oxoglutarate (OGDH, encoded by OGDH/OGDHL) and 2-oxoadipate (OADH, encoded by DHTKD1), respectively. To assess the selectivity in animals, the effects of SP, AP, and their membrane-penetrating triethyl esters (TESP and TEAP) on the rat brain metabolism and animal physiology are compared. Opposite effects of the OGDH and OADH inhibitors on activities of OGDH, malate dehydrogenase, glutamine synthetase, and levels of glutamate, lysine, citrulline, and carnosine are shown to result in distinct physiological responses. ECG is changed by AP/TEAP, whereas anxiety is increased by SP/TESP. The potential role of the ester moiety in the uncharged precursors of the 2-oxo acid dehydrogenase inhibitors is estimated. TMAP is shown to be less efficient than TEAP, in agreement with lower lipophilicity of TMAP vs. TEAP. Non-monotonous metabolic and physiological impacts of increasing OADH inhibition are revealed. Compared to the non-treated animals, strong inhibition of OADH decreases levels of tryptophan and beta-aminoisobutyrate and activities of malate dehydrogenase and pyruvate dehydrogenase, increasing the R–R interval of ECG. Thus, both metabolic and physiological actions of the OADH-directed inhibitors AP/TEAP are different from those of the OGDH-directed inhibitors SP/TESP, with the ethyl ester being more efficient than methyl ester.

Abstract 336: Comparing Of In-vivo Carnosine Levels In Blood, Urine, And Muscle

Background: Dietary supplementation of carnosine, an endogenously produced antioxidant, can be potentially useful in decreasing oxidative stress in the vasculature. However, a safe and accurate measurement of in-vivo Carnosine levels has not been identified. Methods: We enrolled 28 healthy male (50%) and female participants. In-vivo levels of carnosine were measured in three distinct tissues in all 28 participants - urine, blood red blood cells (RBC), and muscle via proton magnetic resonance spectroscopy (1H-MRS). Generalized Linear Model with gamma-distribution and log-link was adjusted for age, sex, race, and diet. Coefficient of variance (CoV) was calculated for 1H-MRS repeat measurements: single location with multiple measurements and multiple locations with single measurements. Results: Univariate regression analysis showed a significant positive association between RBC and urinary carnosine levels (β=0.02; 95% CI: 0.004-0.03; P=0.01). The adjusted model also showed significant positive association between RBC and urinary carnosine levels (β=0.02; 95% CI: 0.002, 0.03; P=0.03). There was no association between 1H-MRS and RBC carnosine or urinary carnosine or carnosine conjugates in urine. The median CoV for multiple readings at single location were 8% and 1% for C2 and C4 peaks respectively, however 12% and 13% for C2 and C4 peaks respectively for single reading at multiple locations. Conclusions: Even though urine, blood (RBC), and muscle represent in-vivo tissues of the human body, the levels of carnosine pools in these different compartments are not in equilibrium with each other. 1H-MRS is highly sensitive to location of measurement. In-vivo levels of carnosine in urine and blood depot are in synchrony and should be used for large scale clinical and research studies like the NEAT clinical trial (NCT03314987), which studies the use of carnosine dietary supplementation to mitigate harmful cardiovascular effects of PM2.5 air pollution.

Plasma Free Amino Acid Profile in HIV-Positive Cases.

Increasing the sensitivity and availability of liquid chromatography tandem mass spectrometry (LC-MS/MS) devices may provide advantages in terms of revealing the changes in metabolic pathways in HIV-positive patients and elucidating the physiopathology. The aim of this study was to determine the difference in amino acid levels between HIV-positive patients and healthy individuals by using LC-MS / MS and investigate its relationship with HIV infection. Concentrations of 36 different amino acids and their derivatives were measured and compared in venous plasma samples from 24 HIV-positive patients and 24 healthy individuals by using the LC-MS/MS method (Shimadzu North America, Columbia, MD, USA). HIV-positive subjects had significantly lower alanine, 1-methyl-L-histidine, valine, aspartate, cysteine, cystine, methionine, lysine, glutamine, imino acid, tyrosine, tryptophan, threonine, sarcosine, and argininosuccinic acid and significantly higher 3-methyl-L -histidine, asparagine, glutamate, and carnosine levels as compared to healthy controls. No significant differences were detected in other amino acids. The significant differences in amino acid profile between HIV-positive and healthy subjects may represent an auxiliary biomarker of cellular damage in asymptomatic HIV-positive patients that may be examined in more detail in further studies. It may also provide guidance for symptomatic cases in terms of the association between symptoms, clinical manifestations, and deficiency or excess of certain amino acids in the context of the complete metabolomics record of HIVpositive patients.

IDF21-0406 Genetic variants in the Carnosine-Carnosinase system and their impact on diabetic nephropathy

Background: The role of carnosine-carnosinase system in diabetic nephropathy has been established through various studies in animal models. It has been proven that low carnosinase secretion promotes high circulating carnosine levels which acts as a protective factor against adverse effects of hyperglycemia on renal cells. While genetic variants in the carnosinase gene (CNDP1) could influence carnosinase concentration, variants in the carnosine synthase gene (CARNS1) which synthesizes carnosine and variants in the SLC15A4 and SLC15A2 genes which are involved in the renal transport of carnosine could influence carnosine concentration thereby causing nephropathy. Aim: To study the association of genetic variants in the carnosine-carnosinase system (CARNS1, CNDP1, SLC15A4 and SLC15A2) with nephropathy and their influence on carnosinase levels in south Indian population. Method: Study Participants: 580 type 2 diabetes individuals without nephropathy (DM) and 597 type 2 diabetes individuals with nephropathy (DN) from Dr. Mohan’s Diabetes Specialities Centre, Chennai, India. Methodology: Genomic DNA was extracted from blood samples using phenol chloroform method. A total of 27 SNPs from the four genes were genotyped using MassARRAY. The levels of carnosinase in serum was measured in 116 DM and 93 DN participants using commercially available ELISA kit. Results: The D18S880 repeat polymorphism (5-8 repeats of Leucine) in CNDP1 gene and rs1626067 SNP of CARNS1 gene showed significant association with DN. The odds ratio for DN after adjusting for potential confounders such as age, sex, BMI, HbA1c, duration of diabetes and systolic blood pressure for the 6L/XL genotype of D18S880 and the GA genotype of rs1626067 as compared to their respective homozygous normal genotypes was 0.67 (95%CI: 0.48-0.94, p=0.022) and 0.68 (95% CI:0.49-0.93, p=0.016) respectively. The levels of carnosinase (mean±SE in picogram/mL) was significantly higher in DN (3.07±0.19) compared to DM group (2.48±0.13, p=0.038). Discussion: This study gains significance as the role of genetic variants in the carnosine-carnosinase system in DN remains largely unexplored. Most of the studies so far have focussed only on the CNDP1 gene. The association of D18S880 Leucine repeat with DN is significant as it is present in the signal peptide region of CNDP1 gene and may play a role in the secretion of carnosinase. The association of rs1626067 SNP in CARNS1 with DN has not been reported so far. This SNP is positioned in the 3́UTR region of CARNS1 and hence could alter the binding of transcription factors and have a regulatory effect. The significant difference in serum carnosinase levels between DM and DN groups was an interesting finding. When the groups were further stratified based on the genotypes, the sample size was less than 50 in each group and was not sufficiently powered to study the correlation of enzyme levels and genotypes. Measuring the levels and activity of carnosinase in larger number of samples will help identify whether the genetic variations influence the enzyme levels. If found, targeted dietary intervention studies giving carnosine supplements to those carrying the susceptible alleles can be undertaken to alleviate the burden of nephropathy.

Muscular carnosine is a marker for cardiorespiratory fitness and cardiometabolic risk factors in men with type 1 diabetes.

Muscle is an essential organ for glucose metabolism and can be influenced by metabolic disorders and physical activity. Elevated muscle carnosine levels have been associated with insulin resistance and cardiometabolic risk factors. Little is known about muscle carnosine in type 1 diabetes (T1D) and how it is influenced by physical activity. The aim of this study was to characterize muscle carnosine in vivo by proton magnetic resonance spectroscopy (1H MRS) and evaluate the relationship with physical activity, clinical characteristics and lipoprotein subfractions. 16 men with T1D (10 athletes/6 sedentary) and 14 controls without diabetes (9/5) were included. Body composition by DXA, cardiorespiratory capacity (VO2peak) and serum lipoprotein profile by proton nuclear magnetic resonance (1H NMR) were obtained. Muscle carnosine scaled to water (carnosineW) and to creatine (carnosineCR), creatine and intramyocellular lipids (IMCL) were quantified in vivo using 1H MRS in a 3T MR scanner in soleus muscle. Subjects with T1D presented higher carnosine CR levels compared to controls. T1D patients with a lower VO2peak presented higher carnosineCR levels compared to sedentary controls, but both T1D and control groups presented similar levels of carnosineCR at high VO2peak levels. CarnosineW followed the same trend. Integrated correlation networks in T1D demonstrated that carnosineW and carnosineCR were associated with cardiometabolic risk factors including total and abdominal fat, pro-atherogenic lipoproteins (very low-density lipoprotein subfractions), low VO2peak, and IMCL. Elevated muscle carnosine levels in persons with T1D and their effect on atherogenic lipoproteins can be modulated by physical activity.