Role of beta-alanine supplementation on muscle carnosine and exercise performance

Effects of microplastics on energy accumulation in a migratory shorebird in the coastal wetlands of the Yellow Sea, China

Microplastic pollution has emerged as a significant environmental concern at the global level, potentially threatening biodiversity conservation and human wellbeing. As an important biological group with a wide global distribution, migratory shorebirds face considerable stress due to plastic and microplastic pollution. However, few studies have explored the ecotoxic impact of microplastic pollution on migratory shorebirds. To investigate the physiological effects of microplastic pollution on migratory shorebirds, this study obtained the morphological data of 79 dunlins at a key stopover site at the midpoint of the East Asian-Australasian Flyway in 2023 autumn. Meanwhile, fecal and blood samples were collected to examine the microplastic abundance accumulated in the body and metabolic levels. Microplastics were detected in 100 % of dunlins, comprising 12 distinct polymer types. The average abundance of microplastics ingested by dunlins was 134.50 items/g, which was higher than the reported abundance of environmental sediment. The present study confirmed that individuals with longer bills ingested more microplastics, resulting in significantly decreased body mass for the same shorebird. Compared to the low contamination group, metabolomic analysis also revealed that dunlins with elevated microplastic contamination exhibited the down-regulation of 10 metabolic pathways, including pyrimidine metabolism, beta-alanine metabolism, and vitamin C metabolism. The findings of this study underscore the potential threat microplastics pose to the health of migratory shorebirds. It is recommended that synergies be developed between microplastic management and biodiversity conservation at global and regional scales, with migratory birds serving as pivotal indicator species.

Fourteen weeks of β-alanine supplementation and HIIT did not improve serum BDNF concentrations and Stroop test performance

This study aimed to investigate whether 14 weeks of β-alanine supplementation and high-intensity intermittent training improves brain-derived neurotrophic factor concentrations and cognitive aspects related to executive functions assessed by the Stroop test. Thirteen healthy and active men underwent a 4-week supplementation period (β-alanine: 6.4 g/d or a placebo) followed by 10-week supplementation combined with high-intensity intermittent training, totaling 14 weeks of intervention. Participants underwent a graded exercise test, while the blood samples for brain-derived neurotrophic factor analysis and the Stroop test (cognitive task) were assessed before and after a high-intensity intermittent exercise (10 runs of 1:1 min effort and a pause ratio at 130% of respiratory compensation point). These measurements were performed three times across the study being at baseline, after 4 weeks of supplementation (POST4weeks) and at the end of the 14 weeks of study (POST14weeks). Compared to baseline values, there were no improvements in brain-derived neurotrophic factor concentrations or Stroop test performance with either β-alanine or high-intensity intermittent training. Lactate peak concentrations in a high-intensity intermittent exercise session also did not differ between groups. However, high-intensity intermittent training did improve some cardiorespiratory parameters (i.e., intensity associated with V̇O2max p=0.01 and respiratory compensation point, p=0.01). In conclusion, β-alanine supplementation alone or associated with high-intensity intermittent training did not improve the brain-derived neurotrophic factor concentrations and Stroop test performance in healthy men.

Metabolic reprogramming and macrophage expansion define ACPA-negative rheumatoid arthritis: insights from single-cell RNA sequencing

Background

Anti-citrullinated peptide antibodies (ACPA)-negative (ACPA-) rheumatoid arthritis (RA) presents significant diagnostic and therapeutic challenges due to the absence of specific biomarkers, underscoring the need to elucidate its distinctive cellular and metabolic profiles for more targeted interventions.

Methods

Single-cell RNA sequencing data from peripheral blood mononuclear cells (PBMCs) and synovial tissues of patients with ACPA- and ACPA+ RA, as well as healthy controls, were analyzed. Immune cell populations were classified based on clustering and marker gene expression, with pseudotime trajectory analysis, weighted gene co-expression network analysis (WGCNA), and transcription factor network inference providing further insights. Cell-cell communication was explored using CellChat and MEBOCOST, while scFEA enabled metabolic flux estimation. A neural network model incorporating key genes was constructed to differentiate patients with ACPA- RA from healthy controls.

Results

Patients with ACPA- RA demonstrated a pronounced increase in classical monocytes in PBMCs and C1QChigh macrophages (p < 0.001 and p < 0.05). Synovial macrophages exhibited increased heterogeneity and were enriched in distinct metabolic pathways, including complement cascades and glutathione metabolism. The neural network model achieved reliable differentiation between patients with ACPA- RA and healthy controls (AUC = 0.81). CellChat analysis identified CD45 and CCL5 as key pathways facilitating macrophage-monocyte interactions in ACPA- RA, prominently involving iron-mediated metabolite communication. Metabolic flux analysis indicated elevated beta-alanine and glutathione metabolism in ACPA- RA macrophages.

Conclusion

These findings underscore that ACPA-negative rheumatoid arthritis is marked by elevated classical monocytes in circulation and metabolic reprogramming of synovial macrophages, particularly in complement cascade and glutathione metabolism pathways. By integrating single-cell RNA sequencing with machine learning, this study established a neural network model that robustly differentiates patients with ACPA- RA from healthy controls, highlighting promising diagnostic biomarkers and therapeutic targets centered on immune cell metabolism.

Advantages of different dietary supplements for elite combat sports athletes: a systematic review and Bayesian network meta-analysis

With an increasing number of studies delving into the impact of dietary supplements on combat sports performance, researchers are actively seeking a more efficient dietary supplement for use in these sports. Nonetheless, controversies persist. Hence, we undertook a systematic review and Bayesian network meta-analysis to discern the most effective dietary supplements in combat sports by synthesizing the available evidence. We conducted a comprehensive search across PubMed, Web of Science, Cochrane, Embase, and SPORTDiscus, covering the period from their establishment to November 2, 2023. Our aim was to identify randomized controlled trials that evaluated the benefits of various dietary supplements for elite combat sports athletes. The risk of bias in these trials was assessed using the revised Cochrane Risk of Bias Tool for Randomized Trials. Subsequently, we employed Bayesian network meta-analysis through R software and Stata 15.0. During the analysis, we performed subgroup analysis based on the type of combat, distinguishing between striking and grappling disciplines. The analysis is based on 67 randomized controlled trials that meet all the inclusion criteria, involving 1026 elite combat sports athletes randomly assigned to 26 different dietary supplements or placebos. Results from the 50 trials included in the network meta-analysis indicate that compared to a placebo, sodium bicarbonate combined with caffeine (SMD: 2.3, 95% CrI: 1.5, 3.2), caffeine (SMD: 0.72, 95% CrI: 0.53, 0.93), beta-alanine (SMD: 0.58, 95% CrI: 0.079, 1.1), and sodium bicarbonate (SMD: 0.54, 95% CrI: 0.30, 0.81) was associated with a statistically significant increase in blood lactate concentrations. Compared to placebo, caffeine (SMD: 0.27, 95% CrI: 0.12, 0.41) was associated with a statistically significant increase in the final heart rate. Compared to placebo, creatine combined with sodium bicarbonate (SMD: 2.2, 95% CrI: 1.5, 3.1), creatine (SMD: 1.0, 95% CrI: 0.38, 1.6), and sodium bicarbonate (SMD: 0.42, 95% CrI: 0.18, 0.66) was associated with a statistically significant increase in mean power. Compared to placebo, creatine combined with sodium bicarbonate (SMD: 1.6, 95% CrI: 0.85, 2.3), creatine (SMD: 1.1, 95% CrI: 0.45, 1.7), and sodium bicarbonate (SMD: 0.35, 95% CrI: 0.11, 0.57) was associated with a statistically significant increase in peak power. Compared to placebo, caffeine (SMD: 1.4, 95% CrI: 0.19, 2.7) was associated with a statistically significant increase in the number of kicks. Compared to placebo, caffeine (SMD: 0.35, 95% CrI: 0.081, 0.61) was associated with a statistically significant increase in the number of throws. This study suggests that a range of dietary supplements, including caffeine, sodium bicarbonate, sodium bicarbonate combined with caffeine, creatine, creatine combined with sodium bicarbonate, and beta-alanine can improve the athletic performance of elite combat sports athletes.

The Possible Roles of β-alanine and L-carnosine in Anti-aging

β-alanine (BA), being a non-proteinogenic amino acid, is an important constituent of L-carnosine (LC), which is necessary for maintaining the muscle buffering capacity and preventing a loss of muscle mass associated with aging effects. BA is also very important for normal human metabolism due to the formation of a part of pantothenate, which is incorporated into coenzyme A. BA is synthesized in the liver, and its combination with histidine results in the formation of LC, which accumulates in the muscles and brain tissues and has a well-defined physiological role as a good buffer for the pH range of muscles that caused its rapidly increased popularity as ergogenic support to sports performance. The main antioxidant mechanisms of LC include reactive oxygen species (ROS) scavenging and chelation of metal ions. With age, the buffering capacity of muscles also declines due to reduced concentration of LC and sarcopenia. Moreover, LC acts as an antiglycation agent, ultimately reducing the development of degenerative diseases. LC has an anti-inflammatory effect in autoimmune diseases such as osteoarthritis. As histidine is always present in the human body in higher concentrations than BA, humans have to get BA from dietary sources to support the required amount of this critical constituent to supply the necessary amount of LC synthesis. Also, BA has other beneficial effects, such as preventing skin aging and intestinal damage, improving the stress-- fighting capability of the muscle cells, and managing an age-related decline in memory and learning. In this review, the results of a detailed analysis of the role and various beneficial properties of BA and LC from the anti-aging perspective are presented.

Simultaneous Analysis of Imidazole Dipeptides, Constituent Amino Acids, and Taurine in Meats Using the Highly Sensitive Labeling Reagent l-FDVDA and PBr Column

Imidazole dipeptides (IDPs) are found in the skeletal muscles and brains of various animals, and they exhibit unique functions like antioxidant and antiaging properties. Despite their importance, the metabolic mechanisms and physiological roles of IDPs remain unclear. Herein, we propose a method for the simultaneous analysis of IDPs, their constituent amino acids, and taurine, which are difficult to separate using conventional labeling reagents or columns, using liquid chromatography-single quadrupole mass spectrometry with PBr column and our highly sensitive labeling reagent, 1-fluoro-2,4-dinitrophenyl-5-l-valine-N,N-dimethylethylenediamineamide (l-FDVDA). This method successfully separated histidine and carnosine enantiomers as well as l-2-oxocarnosine with high antioxidant activity under the same conditions. Our labeling reagent was more stable than the other reagents and did not degrade and desorb from the analytes for at least 1 week at 4 °C. Furthermore, our method allows for the accurate analysis of IDPs, amino acids, and taurine in meats from various animal species, tissues, and breeds.

Single-cell transcriptomics and tissue metabolomics uncover mechanisms underlying wooden breast disease in broilers

Accompanied by the accelerated growth rate of chickens, the quality of chicken meat has deteriorated in recent years. Wooden breast (WB) is a severe myopathy affecting meat quality, and its pathophysiology depends on gene expression and intercellular interactions of various cell types, which are not yet fully understood. We have performed a comprehensive transcriptomic and metabolomic atlas of chicken WB muscle. Our data showed a significant increase in the number of immune cells, WB muscle displayed a unique cluster of macrophages (cluster 11), distinct from the M1 and M2 macrophages. Regarding the myocytes, the most significant differences were the decrease in cell number and the intensification of fatty deposits. Satellite cells were involved in muscle repair and regeneration producing more collagen. Interestingly, the interaction network in the WB group was weaker compared to that in normal breast muscle. Additionally, we found six key differential metabolites across 22 pathways. When WB occurs, myocytes and endothelial cells undergo apoptosis, macrophages are activated and exert immune functions, satellite cells participate in muscle rebuilding and repair, and the content of metabolites undergoes significant changes. This cell transcriptome profile provides an essential reference for future studies on the development and remodeling of WB.

Effect of Beta-Alanine Supplementation on Maximal Intensity Exercise in Trained Young Male Individuals: A Systematic Review and Meta-Analysis

Beta-alanine is a nonessential amino acid that is commonly used to improve exercise performance. It could influence the buffering of hydrogen ions produced during intense exercise and delay fatigue, providing a substrate for increased synthesis of intramuscular carnosine. This systematic review evaluates the effects of beta-alanine supplementation on maximal intensity exercise in trained, young, male individuals. Six databases were searched on August 10, 2023, to identify randomized, double-blinded, placebo-controlled trials investigating the effect of chronic beta-alanine supplementation in trained male individuals with an age range of 18-40 years. Studies evaluating exercise performance through maximal or supramaximal intensity efforts falling within the 0.5-10 min duration were included. A total of 18 individual studies were analyzed, employing 18 exercise test protocols and 15 outcome measures in 331 participants. A significant (p = .01) result was observed with an overall effect size of 0.39 (95% confidence interval [CI] [0.09, 0.69]), in favor of beta-alanine supplementation versus placebo. Results indicate significant effects at 4 weeks of supplementation, effect size 0.34 (95% CI [0.02, 0.67], p = .04); 4-10 min of maximal effort, effect size 0.55 (95% CI [0.07, 1.04], p = .03); and a high beta-alanine dosage of 5.6-6.4 g per day, effect size 0.35 (95% CI [0.09, 0.62], p = .009). The results provide insights into which exercise modality will benefit the most, and which dosage protocols and durations stand to provide the greatest ergogenic effects. This may be used to inform further research, and professional or recreational training design, and optimization of supplementation strategies.

Histidine-containing dipeptide supplementation improves delayed recall: a systematic review and meta-analysis

CONTEXT

Histidine-containing dipeptides (carnosine, anserine, beta-alanine and others) are found in human muscle tissue and other organs like the brain. Data in rodents and humans indicate that administration of exogenous carnosine improved cognitive performance. However, RCTs results vary.

OBJECTIVES

To perform a systematic review and meta-analysis of randomized controlled trials (RCTs) of histidine-containing dipeptide (HCD) supplementation on cognitive performance in humans to assess its utility as a cognitive stabiliser.

DATA SOURCES

OVID Medline, Medline, EBM Reviews, Embase, and Cumulative Index to Nursing and Allied Health Literature databases from 1/1/1965 to 1/6/2022 for all RCT of HCDs were searched.

DATA EXTRACTION

2653 abstracts were screened, identifying 94 full-text articles which were assessed for eligibility. Ten articles reporting the use of HCD supplementation were meta-analysed.

DATA ANALYSIS

The random effects model has been applied using the DerSimonian-Laird method. HCD treatment significantly increased performance on Wechsler Memory Scale (WMS) -2 Delayed recall (Weighted mean difference (WMD) (95% CI (CI)) = 1.5 (0.6, 2.5), P < .01). Treatment with HCDs had no effect on Alzheimer's Disease Assessment Scale-Cognitive (WMD (95% CI) = -0.2 (-1.1, 0.7), P = .65, I2 = 0%), Mini-Mental State Examination (WMD (95% CI) = 0.7 (-0.2, 1.5), P = .14, I2 = 42%), The Wechsler Adult Intelligence Scale (WAIS) Digit span Backward (WMD (95% CI) = 0.1 (-0.3, 0.5), P = .51, I2 = 0%), WAIS digit span Forward (WMD (95% CI) = 0.0 (-0.3, 0.4), P = .85, I2 = 33%) and the WMS-1 Immediate recall (WMD (95% CI) = .7 (-.2, 1.5), P = .11, I2 = 0%). The effect on delayed recall remained in subgroup meta-analysis performed on studies of patients without mild cognitive impairment (MCI), and in those without MCI where average age in the study was above 65.

CONCLUSION

HCD, supplementation improved scores on the Delayed recall examination, a neuropsychological test affected early in Alzheimer's disease. Further studies are needed in people with early cognitive impairment with longer follow-up duration and standardization of carnosine doses to delineate the true effect.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42017075354.

Nutritional contents and antimicrobial activity of the culinary-medicinal mushroom Leccinum scabrum

Leccinum scabrum (Bull.) Gray (Boletaceae) is an edible mycorrhizal species with potential application interest due to its food and medicinal properties. A field investigation carried out during summer in the Białowieża Primeval Forest, located along the border between Belarus and Poland allowed to collect samples for chemical composition analysis and antibacterial activity evaluation. Mushroom extracts were prepared with microwave-assisted as well as ultrasound-assisted extraction techniques (UAE and MAE). The analysis of a dry sample of L. scabrum showed a significant content of vitamins and minerals and also a remarkable content of carbohydrates, protein, dietary fibre, total sugars, total free amino acids, and polyunsaturated fatty acids. The antibacterial activity of L. scabrum aqueous extracts showed inhibitory activity against all tested bacteria. In general, MAE extract exhibits a higher inhibition activity against Listeria monocytogenes ATCC 19114. As regards the Minimum Inhibitory Concentration (MIC) values, the high antibacterial activity of MAE extract was detected for L. monocytogenes ATCC 19114 and Escherichia coli ATCC 25922. Regarding UAE, high antibacterial activity was detected for Salmonella enterica ATCC 13076 and L. monocytogenes ATCC 19114. Based on data hereby reported, L. scabrum is a culinary-medicinal mushroom with a promising potential use as a high-quality food and nutraceutical mycological resource.

Comparative evaluation of different modalities for measuring in vivo carnosine levels

Carnosine is an endogenous di-peptide (β-alanine -L- histidine) involved in maintaining tissue homeostasis. It is most abundant in skeletal muscle where its concentration has been determined in biopsy samples using tandem mass spectrometry (MS-MS). Carnosine levels can also be assessed in intact leg muscles by proton magnetic resonance spectroscopy (1H-MRS) or in blood and urine samples using mass spectrometry. Nevertheless, it remains uncertain how carnosine levels from these distinct compartments are correlated with each other when measured in the same individual. Furthermore, it is unclear which measurement modality might be most suitable for large-scale clinical studies. Hence, in 31 healthy volunteers, we assessed carnosine levels in skeletal muscle, via 1H-MRS, and in erythrocytes and urine by MS-MS. While muscle carnosine levels were higher in males (C2 peak, p = 0.010; C4 peak, p = 0.018), there was no sex-associated difference in urinary (p = 0.433) or erythrocyte (p = 0.858) levels. In a linear regression model adjusted for age, sex, race, and diet, there was a positive association between erythrocyte and urinary carnosine. However, no association was observed between 1H-MRS and erythrocytes or urinary measures. In the relationship between muscle versus urinary and erythrocyte measures, females had a positive association, while males did not show any association. We also found that 1H-MRS measures were highly sensitive to location of measurement. Thus, it is uncertain whether 1H-MRS can accurately and reliably predict endogenous carnosine levels. In contrast, urinary and erythrocyte carnosine measures may be stable and in greater synchrony, and given financial and logistical concerns, may be a feasible alternative for large-scale clinical studies.

Food for thought: Physiological considerations for nutritional ergogenic efficacy

Top-class athletes have optimized their athletic performance largely through adequate training, nutrition, recovery, and sleep. A key component of sports nutrition is the utilization of nutritional ergogenic aids, which may provide a small but significant increase in athletic performance. Over the last decade, there has been an exponential increase in the consumption of nutritional ergogenic aids, where over 80% of young athletes report using at least one nutritional ergogenic aid for training and/or competition. Accordingly, due to their extensive use, there is a growing need for strong scientific investigations validating or invalidating the efficacy of novel nutritional ergogenic aids. Notably, an overview of the physiological considerations that play key roles in determining ergogenic efficacy is currently lacking. Therefore, in this brief review, we discuss important physiological considerations that contribute to ergogenic efficacy for nutritional ergogenic aids that are orally ingested including (1) the impact of first pass metabolism, (2) rises in systemic concentrations, and (3) interactions with the target tissue. In addition, we explore mouth rinsing as an alternate route of ergogenic efficacy that bypasses the physiological hurdles of first pass metabolism via direct stimulation of the central nervous system. Moreover, we provide real-world examples and discuss several practical factors that can alter the efficacy of nutritional ergogenic aids including human variability, dosing protocols, training status, sex differences, and the placebo effect. Taking these physiological considerations into account will strengthen the quality and impact of the literature regarding the efficacy of potential ergogenic aids for top-class athletes.

A Comparative Biochemical Study Between L-Carnosine and β-Alanine in Amelioration of Hypobaric Hypoxia-Induced Skeletal Muscle Protein Loss

Rathor, Richa, Sukanya Srivastava, and Geetha Suryakumar. A comparative biochemical study between L-carnosine and β-alanine in amelioration of hypobaric hypoxia-induced skeletal muscle protein loss. High Alt Med Biol. 24:302-311, 2023. Background: Carnosine (CAR; β-alanyl-L-histidine), a biologically active dipeptide is known for its unique pH-buffering capacity, metal chelating activity, and antioxidant and antiglycation property. β-Alanine (ALA) is a nonessential amino acid and used to enhance performance and cognitive functions. Hypobaric hypoxia (HH)-induced muscle protein loss is regulated by multifaceted signaling pathways. The present study investigated the beneficial effects of CAR and ALA against HH-associated muscle loss. Methodology: Simulated HH exposure was performed in an animal decompression chamber. Gastric oral administration of CAR (50 mg·kg-1) and ALA (450 mg·kg-1) were given daily for 3 days and at the end of the treatment, hindlimb skeletal muscle tissue was excised for western blot and biochemical assays. Results: Cosupplementation of CAR and ALA alone was able to ameliorate the hypoxia-induced inflammation, oxidative stress (FOXO), ER stress (GRP-78), and atrophic signaling (MuRF-1) in the skeletal muscles. Creatinine phospho kinase activity and apoptosis were also decreased in CAR- and ALA-supplemented rats. However, CAR showed enhanced protection in HH-induced muscle loss as CAR supplementation was able to enhance protein concentration, body weight, and decreased the protein oxidation and ALA administration was not able to restore the same. Conclusions: Hence, the present comprehensive study supports the fact that CAR (50 mg·kg-1) is more beneficial as compared with ALA (450 mg·kg-1) in ameliorating the hypoxia-induced skeletal muscle loss.

Effects of acute beta-alanine supplementation on post-exertion rating of per-ceived exertion, heart rate, blood lactate, and physical performance on the 6-minute race test in middle-distance runners

Introduction

Background: the use of beta-alanine (BA) to increase physical performance in the heavy-intensity domain zone (HIDZ) is widely documented. However, the effect of this amino acid on the post-exertion rating of perceived exertion (RPE), heart rate (HR), and blood lactate (BL) is still uncertain. Objectives: a) to determine the effect of acute BA supplementation on post-exertion RPE, HR, and BL in middle-distance athletes; and b) to determine the effect of acute BA supplementation on physical performance on the 6-minute race test (6-MRT). Material and methods: the study included 12 male middle-distance athletes. The de-sign was quasi-experimental, intrasubject, double-blind & crossover. It had two treat-ments (low-dose BA [30 mg·kg-1] and high-dose BA [45 mg·kg-1]) and a placebo, 72 hours apart. The effect of BA was evaluated at the end of the 6-MRT and post-exertion. The variables were RPE, HR and BL, and 6-MRT (m) distance. The statistical analysis included a repeated-measures ANOVA (p < 0.05). Results: the analysis evidenced no significant differences at the end of 6-MRT for all variables (p ˃ 0.05). However, both doses of BA generated a lower post-exertion RPE. The high dose of BA caused significant increases in post-exertion BL (p ˂ 0.05). Conclusion: acute supplementation with BA generated a lower post-exertion RPE. This decrease in RPE and the post-exertion BL increase could be related to an increase in physical performance in HIDZ.

Anabolic Resistance in the Pathogenesis of Sarcopenia in the Elderly: Role of Nutrition and Exercise in Young and Old People

The development of sarcopenia in the elderly is associated with many potential factors and/or processes that impair the renovation and maintenance of skeletal muscle mass and strength as ageing progresses. Among them, a defect by skeletal muscle to respond to anabolic stimuli is to be considered. Common anabolic stimuli/signals in skeletal muscle are hormones (insulin, growth hormones, IGF-1, androgens, and β-agonists such epinephrine), substrates (amino acids such as protein precursors on top, but also glucose and fat, as source of energy), metabolites (such as β-agonists and HMB), various biochemical/intracellular mediators), physical exercise, neurogenic and immune-modulating factors, etc. Each of them may exhibit a reduced effect upon skeletal muscle in ageing. In this article, we overview the role of anabolic signals on muscle metabolism, as well as currently available evidence of resistance, at the skeletal muscle level, to anabolic factors, from both in vitro and in vivo studies. Some indications on how to augment the effects of anabolic signals on skeletal muscle are provided.

The gut microbiota from maintenance hemodialysis patients with sarcopenia influences muscle function in mice

Background

Sarcopenia is a common complication in patients undergoing maintenance hemodialysis (MHD). Growing evidence suggests a close relationship between the gut microbiota and skeletal muscle. However, research on gut microbiota in patients with sarcopenia undergoing MHD (MS) remains scarce. To bridge this knowledge gap, we aimed to evaluate the pathogenic influence of gut microbiota in the skeletal muscle of patients with MS, to clarify the causal association between gut microbiota and skeletal muscle symptoms in patients with MS and identify the potential mechanisms underlying this causal association.

Methods

Fecal samples were collected from 10 patients with MS and 10 patients without MS (MNS). Bacteria were extracted from these samples for transplantation. Mice (n=42) were randomly divided into three groups and, after antibiotic treatment, fecal microbiota transplantation (FMT) was performed once a day for 3 weeks. Skeletal muscle and fecal samples from the mice were collected for 16S rRNA gene sequencing and for histological, real-time PCR, and metabolomic analyses.

Results

Mice colonized with gut microbiota from MS patients exhibited notable decreases in muscle function and muscle mass, compared with FMT from patients with MNS. Moreover, 16S rRNA sequencing revealed that the colonization of MS gut microbiota reduced the abundance of Akkermansia in the mouse intestines. Metabolome analysis revealed that seven metabolic pathways were notably disrupted in mice transplanted with MS microbiota.

Conclusion

This study established a connection between skeletal muscle and the gut microbiota of patients with MS, implying that disruption of the gut microbiota may be a driving factor in the development of skeletal muscle disorders in patients undergoing MHD. This finding lays the foundation for understanding the pathogenesis and potential treatment methods for sarcopenia in patients undergoing MHD.

β-Alanine Supplementation in Combat Sports: Evaluation of Sports Performance, Perception, and Anthropometric Parameters and Biochemical Markers-A Systematic Review of Clinical Trials

β-alanine does not have an ergogenic effect by itself, but it does as a precursor for the synthesis of carnosine in human skeletal muscle. β-alanine and carnosine together help improve the muscles' functionality, especially in high-intensity exercises such as combat sports. Therefore, β-alanine could be considered a nutritional ergogenic aid to improve sports performance in combat athletes. We aimed to critically review clinical trial evidence on the impact of β-alanine supplementation on sports performance, perception, and anthropometric parameters, as well as circulating biochemical markers in combat athletes. This systematic review was conducted following the specific methodological guidelines of the Preferred Report Items for Systematic Reviews and Meta-Analyses guidelines (PRISMA), the PICOS question model, the Critical Review Form of McMaster, and the PEDro scale. Furthermore, the Cochrane risk-of-bias assessment tool was used. The search was carried out in the SCOPUS, Web of Science (WOS), and Medline (PubMed) databases for studies published from the beginning of the database until July 31, 2023. Of the 41 registers identified, only 7 met the established criteria and were included in this systematic review. Overall, performance parameters related to strength, power, total exercise work capacity, and combat-specific parameters were significantly improved (p < 0.05). Perception parameters increased non-significantly (p > 0.05). Regarding biochemical parameters, carnosine increased significantly (p < 0.05), pH decreased non-significantly (p > 0.05), and the results for blood bicarbonate and blood lactate were heterogeneous. Finally, there was a non-significant (p > 0.05) improvement in the anthropometric parameters of lean mass and fat mass. β-alanine supplementation appears to be safe and could be a suitable nutritional ergogenic aid for combat athletes.

Comparative Quality Traits, Flavor Compounds, and Metabolite Profile of Korean Native Black Goat Meat

Although goat meat has several health benefits than other red meats but comsumers reluctant it due to its unpleasant flavor. This study aimed to investigate the odorant of goat meat as well as compare the quality traits of meat regarding sex status. The loin meats [non-castrated male (NCM), castrated male (CM), and female (FM)] were collected and stored at 4°C in a laboratory refrigerator and analyzed on the 1^st, 5^th, and 8^th consecutive days. The moisture content was the lowest and the protein content was highest in FM (p<0.05). Fat and ash content in NCM and FM were similar while lowest in CM. The CIE L* was significantly higher in NCM, but there were no significant differences of CIE a* and CIE b* within groups at initial day. The color intensity increased on the 5^th storage day and decreased again after the 8^th storage day, except in NCM. NCM displayed the highest thiobarbituric acid reactive substances value (p<0.05), whereas CM displayed a higher pH value than other groups throughout the storage period. Indole levels were the highest in NCM (0.031 mg/kg); however, skatole levels were not significant differences across all treatments (p>0.05). No significant difference was observed in the fatty acid composition between NCM and CM (p>0.05), whereas a significant difference was observed in FM (p<0.05). Most of the water-soluble metabolites showed significant differences between sexes. Overall, sex status effects on quality properties of meat and castration can improve the overall sensory acceptance by reducing goaty flavor of Korean native black goat meat.

Neurocirculatory regulation and adaptations to exercise in chronic kidney disease

Chronic kidney disease (CKD) is characterized by pronounced exercise intolerance and exaggerated blood pressure reactivity during exercise. Classic mechanisms of exercise intolerance in CKD have been extensively described previously and include uremic myopathy, chronic inflammation, malnutrition, and anemia. We contend that these classic mechanisms only partially explain the exercise intolerance experienced in CKD and that alterations in cardiovascular and autonomic regulation also play a key contributing role. The purpose of this review is to examine the physiological factors that contribute to neurocirculatory dysregulation during exercise and discuss the adaptations that result from regular exercise training in CKD. Key neurocirculatory mechanisms contributing to exercise intolerance in CKD include augmentation of the exercise pressor reflex, aberrations in neurocirculatory control, and increased neurovascular transduction. In addition, we highlight how some contributing factors may be improved through exercise training, with a specific focus on the sympathetic nervous system. Important areas for future work include understanding how the exercise prescription may best be optimized in CKD and how the beneficial effects of exercise training may extend to the brain.

The Effect of β-Alanine Supplementation on Performance, Cognitive Function and Resiliency in Soldiers

β-alanine is a nonessential amino acid that combines with the amino acid histidine to form the intracellular dipeptide carnosine, an important intracellular buffer. Evidence has been well established on the ability of β-alanine supplementation to enhance anaerobic skeletal muscle performance. As a result, β-alanine has become one of the more popular supplements used by competitive athletes. These same benefits have also been reported in soldiers. Evidence accumulated over the last few years has suggested that β-alanine can result in carnosine elevations in the brain, which appears to have broadened the potential effects that β-alanine supplementation may have on soldier performance and health. Evidence suggests that β-alanine supplementation can increase resilience to post-traumatic stress disorder, mild traumatic brain injury and heat stress. The evidence regarding cognitive function is inconclusive but may be more of a function of the stressor that is applied during the assessment period. The potential benefits of β-alanine supplementation on soldier resiliency are interesting but require additional research using a human model. The purpose of this review is to provide an overview of the physiological role of β-alanine and why this nutrient may enhance soldier performance.

Acute Supplementation with Beta-Alanine Improves Performance in Aerobic-Anaerobic Transition Zones in Endurance Athletes

To determine the acute effect of low and high-dose BA trials on maximal aerobic speed (MAS) in endurance athletes. We hypothesized that high doses of BA have a greater effect than low doses, both compared to baseline.

Twelve male endurance athletes volunteered for the study (age = 21.8 ± 2.37 years, weight = 69.8 ± 4.36 kg, height = 174 ± 5.45 cm, maximal oxygen uptake = 59.6 ± 3.77 mLO₂·kg^-1·min^-1). The experimental design applied was randomized cross-over, double-blind. Treatment included three 6-minute run tests (6-MRT), the first as a baseline, then randomized 6-MRT with low (30 mg·kg^-1) and high (45 mg·kg^-1) dose BA trials. The 6-MRTs were separated by 72 hours. The main variable of the study was the distance (m) performed in the 6-MRT. Differences between tests were established through ANOVA and Tukey's multiple comparison tests (p < 0.05).

The analysis showed significant differences between baseline and both doses (p < 0.001). No significant differences were observed between low and high-dose BA trials (p > 0.05).

Both 30 and 45 mg·kg^-1 of BA increased physical performance at maximal aerobic speed in endurance athletes. The acute intake formats described in the present investigation may be helpful for endurance athletes training and competing in aerobic-anaerobic transition zones.

Intake of Food Supplements, Caffeine, Green Tea and Protein Products among Young Danish Men Training in Commercial Gyms for Increasing Muscle Mass

Sixty-three men (15-35 years of age) regularly training in Danish gyms and supplement users were interviewed about the use of supplemental protein and food supplements, intake of caffeine- and (-)-epigallocathechin-3-gallate (EGCG)-containing supplements and beverages and any experienced adverse effects. Protein powder (60%), fish oil (54%) and multivitamin/mineral supplements (41%) were the most popular products. The daily supplementary protein intake (mean 0.42 g/kg body weight, users only) in adult men contributed substantially to their protein intake and exceeded the recommended allowance (0.83 g/kg body weight) for six adult participants (14%). Thirty-eight percent of the adult men exceeded the daily caffeine intake presumed to be safe (400 mg) with coffee as the main contributor. Thirty percent drank green tea and among this percentage, two participants had an extreme daily intake (1.5 and 2 -L). EGCG intake could not be estimated from the food supplements due to the lack of label information. Eighteen participants (29%) reported having experienced adverse effects but seventeen did not consult a physician or report the adverse effect to the Danish food authority. The most common adverse effects were insomnia, shaking, headache and palpitations, itching of the skin and stinging. Pre-workout products accounted for 53% of the adverse effects. Three adverse effects came after intake of two brands of supplements known to have contained substances such as 1,3-dimethylamine or derivatives of phenylethylamines previously having caused serious adverse effects.

International society of sports nutrition position stand: tactical athlete nutrition

This position stand aims to provide an evidence-based summary of the energy and nutritional demands of tactical athletes to promote optimal health and performance while keeping in mind the unique challenges faced due to work schedules, job demands, and austere environments. After a critical analysis of the literature, the following nutritional guidelines represent the position of the International Society of Sports Nutrition (ISSN).

General Recommendations

Nutritional considerations should include the provision and timing of adequate calories, macronutrients, and fluid to meet daily needs as well as strategic nutritional supplementation to improve physical, cognitive, and occupational performance outcomes; reduce risk of injury, obesity, and cardiometabolic disease; reduce the potential for a fatal mistake; and promote occupational readiness.

Military Recommendations

Energy demands should be met by utilizing the Military Dietary Reference Intakes (MDRIs) established and codified in Army Regulation 40-25. Although research is somewhat limited, military personnel may also benefit from caffeine, creatine monohydrate, essential amino acids, protein, omega-3-fatty acids, beta-alanine, and L-tyrosine supplementation, especially during high-stress conditions.

First Responder Recommendations

Specific energy needs are unknown and may vary depending on occupation-specific tasks. It is likely the general caloric intake and macronutrient guidelines for recreational athletes or the Acceptable Macronutrient Distribution Ranges for the general healthy adult population may benefit first responders. Strategies such as implementing wellness policies, setting up supportive food environments, encouraging healthier food systems, and using community resources to offer evidence-based nutrition classes are inexpensive and potentially meaningful ways to improve physical activity and diet habits. The following provides a more detailed overview of the literature and recommendations for these populations.

Physiological Roles of Carnosine in Myocardial Function and Health

Carnosine is a pleiotropic histidine-containing dipeptide synthesized from β-alanine and l-histidine, with the intact dipeptide and constituent amino acids being available from the diet. The therapeutic application of carnosine in myocardial tissue is promising, with carnosine playing a potentially beneficial role in both healthy and diseased myocardial models. This narrative review discusses the role of carnosine in myocardial function and health, including an overview of the metabolic pathway of carnosine in the myocardial tissue, the roles carnosine may play in the myocardium, and a critical analysis of the literature, focusing on the effect of exogenous carnosine and its precursors on myocardial function. By so doing, we aim to identify current gaps in the literature, thereby identifying considerations for future research.

Effects of beta-alanine supplementation on body composition: a GRADE-assessed systematic review and meta-analysis

Purpose

Previous studies have suggested that beta-alanine supplementation may benefit exercise performance, but current evidence regarding its effects on body composition remains unclear. This systematic review and meta-analysis aimed to investigate the effects of beta-alanine supplementation on body composition indices.

Methods

Online databases, including PubMed/Medline, Scopus, Web of Science, and Embase, were searched up to April 2021 to retrieve randomized controlled trials (RCTs), which examined the effect of beta-alanine supplementation on body composition indices. Meta-analyses were carried out using a random-effects model. The I² index was used to assess the heterogeneity of RCTs.

Results

Among the initial 1413 studies that were identified from electronic databases search, 20 studies involving 492 participants were eligible. Pooled effect size from 20 studies indicated that beta-alanine supplementation has no effect on body mass (WMD: −0.15 kg; 95% CI: −0.78 to 0.47; p = 0.631, I² = 0.0%, p = 0.998), fat mass (FM) (WMD: −0.24 kg; 95% CI: −1.16 to 0.68; p = 0.612, I² = 0.0%, p = 0.969), body fat percentage (BFP) (WMD: −0.06%; 95% CI: −0.53 to 0.40; p = 0.782, I² = 0.0%, p = 0.936), and fat-free mass (FFM) (WMD: 0.05 kg; 95% CI: −0.71 to 0.82; p = 0.889, I² = 0.0%, p = 0.912). Subgroup analyses based on exercise type (resistance training [RT], endurance training [ET], and combined training [CT]), study duration (<8 and ≥8 weeks), and beta-alanine dosage (<6 and ≥6 g/d) demonstrated similar results. Certainty of evidence across outcomes ranged from low to moderate.

Conclusions

This meta-analysis study suggests that beta-alanine supplementation is unlikely to improve body composition indices regardless of supplementation dosage and its combination with exercise training. No studies have examined the effect of beta-alanine combined with both diet and exercise on body composition changes as the primary variable. Therefore, future studies examining the effect of the combination of beta-alanine supplementation with a hypocaloric diet and exercise programs are warranted.

Effects of Different Prenatal Nutrition Strategies on the Liver Metabolome of Bulls and Its Correlation with Body and Liver Weight

This study investigated the effect of prenatal nutrition on liver metabolome and on body (BW) and liver weight (LW) of Nellore bulls at slaughter. Three treatments were applied in 126 cows during pregnancy: NP—control (mineral supplementation); PP—protein-energy supplementation in the third trimester; and FP—protein-energy supplementation during the entire pregnancy. Offspring BW and LW were evaluated, and a targeted metabolomics analysis was performed on their livers (n = 18, 22.5 ± 1 months of age). Data were submitted to principal component analysis (PCA), analysis of variance (ANOVA), enrichment analysis, and Pearson’s correlation analysis. The phenotypes did not show differences between treatments (p > 0.05). Metabolites PCA showed an overlap of treatment clusters in the analysis. We found significant metabolites in ANOVA (p ≤ 0.05; Glycine, Hydroxytetradecadienylcarnitine, Aminoadipic acid and Carnosine). Enrichment analysis revealed some biological processes (Histidine metabolism, beta-Alanine metabolism, and Lysine degradation). Pearson’s correlation analysis showed 29 significant correlated metabolites with BW and 1 metabolite correlated with LW. In summary, prenatal nutrition did not show effects on the phenotypes evaluated, but affected some metabolites and biological pathways, mainly related to oxidative metabolism. In addition, BW seems to influence the hepatic metabolome more than LW, due to the amount and magnitude of correlations found.

Endogenous dipeptide-carnosine supplementation ameliorates hypobaric hypoxia-induced skeletal muscle loss via attenuating endoplasmic reticulum stress response and maintaining proteostasis

High altitude is an environmental stress that is accompanied with numerous adverse biological responses, including skeletal muscle weakness and muscle protein loss. Skeletal muscle wasting is an important clinical problem, progressing to critical illness, associated with increased morbidity and mortality. The present study explores the protective efficacy of endogenous dipeptide, carnosine (CAR), supplementation in ameliorating skeletal muscle protein loss under hypobaric hypoxia (HH). Male Sprague-Dawley rats (n = 5) were randomly divided into control group, HH-exposed group (3 days HH exposure equivalent to 7,620 m), and HH-exposed rats supplemented with carnosine (3 days; 150 mg/kg b.w, orally) (HH + CAR). HH-exposed rats supplemented with CAR ameliorated HH-induced oxidative protein damage, lipid peroxidation, and maintained pro-inflammatory cytokines levels. HH-associated muscle protein degradative pathways, including calpain, ubiquitination, endoplasmic reticulum stress, autophagy, and apoptosis were also regulated in carnosine-supplemented rats. Further, the muscle damage marker, the levels of serum creatine phosphokinase were also reduced in HH + CAR co-supplemented rats which proved the protective efficacy of CAR against hypobaric hypoxia-induced muscle protein loss. Altogether, CAR supplementation ameliorated HH-induced skeletal muscle protein loss via performing multifaceted ways, mainly by maintaining redox homeostasis and proteostasis in skeletal muscle.

A Multi-Ingredient Formula Ameliorates Exercise-Induced Fatigue by Changing Metabolic Pathways and Increasing Antioxidant Capacity in Mice

Multiple mechanisms are involved in exercise-induced fatigue, including energy depletion, metabolite accumulation, and oxidative stress, etc. The mechanistic findings provide a rationale for a multi-targeted approach to exercise-induced fatigue management. This study created a multi-ingredient formula mixed with valine, isoleucine, leucine, β-alanine, creatine, l-carnitine, quercetin, and betaine, based on the functional characteristics of these agents, and evaluated the preventive effect of this mechanism-based formula on exercise-induced fatigue. Results showed that the 7-d formula supplement significantly increased the running duration time of mice by 14% and the distance by 20% in an exhaustive treadmill test, indicating that the formula could delay fatigue appearance and improve exercise performance. Mechanistically, the formula enhanced fatty acid oxidation and spared liver glycogen by regulating the fat/glucose metabolism-related signaling pathways, including phospho-adenosine monophosphate-activated protein kinase α (p-AMPKα), phospho-acetyl CoA carboxylase (p-ACC), carnitine palmitoyl-transferase 1B (CPT1B), fatty acid translocase (CD36), and glucose transporter type 4 (GLUT4), and increased antioxidant capacity. The findings suggested that the formula tested in this study effectively ameliorated exercise-induced fatigue by targeting multi-signaling pathways, showing promise as a regimen to fight exercise-induced fatigue.

Effect of β-alanine and sodium bicarbonate co-supplementation on the body's buffering capacity and sports performance: A systematic review

Muscle acidification is one of the main factors causing fatigue during exercise, thus compromising performance. The sport supplements beta alanine (β-A) and sodium bicarbonate (SB) are thought to enhance the effects of the body's buffer systems by reducing H⁺ concentrations. The aim of this systematic review was to analyze the effects of β-A and SB co-supplementation on the organism's buffering capacity and sport performance. The databases PubMed, Web of Science, Medline, CINAHL and SPORTDiscus were searched until November 2021 following PRISMA guidelines. Randomized controlled trials, at least single-blind, performed in athletes of any age were considered. Nine studies including a total of 221 athletes were identified for review. Athletes were supplemented with β-A and SB while they performed exercise tests to assess physical performance and buffer capacity. Five of the nine studies indicated there was some additional improvement in buffering capacity and performance with co-supplementation, while one study concluded that the effect was comparable to the added effects of the individual supplements. According to the results of the studies reviewed, we would recommend β-A and SB co-supplementation during high intensity exercises lasting between 30 s and 10 min.

Anti-cancer actions of carnosine and the restoration of normal cellular homeostasis

Carnosine is a naturally occurring dipeptide found in meat. Alternatively it can be formed through synthesis from the amino acids, β-alanine and L-histidine. Carnosine has long been advocated for use as an anti-oxidant and anti-glycating agent to facilitate healthy ageing, and there have also been reports of it having anti-proliferative effects that have beneficial actions against the development of a number of different cancers. Carnosine is able to undertake multiple molecular processes, and it's mechanism of action therefore remains controversial - both in healthy tissues and those associated with cancer or metabolic diseases. Here we review current understanding of its mechanistic role in different physiological contexts, and how this relates to cancer. Carnosine turns over rapidly in the body due to the presence of both serum and tissue carnosinase enzymes however, so its use as a dietary supplement would require ingestion of multiple daily doses. Strategies are therefore being developed that are based upon either resistance of carnosine analogs to enzymatic turnover, or else β-alanine supplementation, and the development of these potential therapeutic agents is discussed.

Isolation of balenine from opah (Lampris megalopsis) muscle and comparison of antioxidant and iron-chelating activities with other major imidazole dipeptides

Balenine (Bal) in opah muscle was extracted using hot water and purified by ion-exchange chromatography and recrystallization to provide 41 g of over 95% pure Bal from 1 kg of opah muscle. The structure of purified Bal was identical to that of an authentic Bal standard by NMR analysis. The antioxidant (ORAC and HORAC values) and Fe(II) ion-chelating abilities of purified Bal were examined by comparison with two major imidazole dipeptides, carnosine (Car) and anserine (Ans). Opah-derived Bal showed significantly higher ORAC and HORAC values and Fe(II) ion-chelating ability at 0.3 mM. In silico molecular simulation revealed that Bal and Car formed hydrogen bonds between the hydrogen atom of the imidazole imino group and the carboxyl carbonyl oxygen, whereas Ans did not. The proposed method for extracting and purifying Bal from opah muscle suggests that opah can be utilized as a functional food or Bal resource.

Cerebellar and multi-system metabolic reprogramming associated with trauma exposure and post-traumatic stress disorder (PTSD)-like behavior in mice

Mitochondrial metabolism is increasingly implicated in psychopathologies and mood disorders, including post-traumatic stress disorder (PTSD). We recently reported that mice exposed to a novel paradigm for the induction of PTSD-like behavior displayed reduced mitochondrial electron transport chain (mtETC) complex activity as well as decreased multi-system fatty acid oxidation (FAO) flux. Based on these results, we hypothesized that stressed and PTSD-like animals would display evidence of metabolic reprogramming in both cerebellum and plasma consistent with increased energetic demand, mitochondrial metabolic reprogramming, and increased oxidative stress. We performed targeted metabolomics in both cerebellar tissue and plasma, as well as untargeted nuclear magnetic resonance (NMR) spectroscopy in the cerebellum of 6 PTSD-like and 7 resilient male mice as well as 7 trauma-naïve controls. We identified numerous differences in amino acids and tricarboxylic acid (TCA) cycle metabolite concentrations in the cerebellum and plasma consistent with altered mitochondrial energy metabolism in trauma exposed and PTSD-like animals. Pathway analysis identified metabolic pathways with significant metabolic pathway shifts associated with trauma exposure, including the tricarboxylic acid cycle, pyruvate, and branched-chain amino acid metabolism in both cerebellar tissue and plasma. Altered glutamine and glutamate metabolism, and arginine biosynthesis was evident uniquely in cerebellar tissue, while ketone body levels were modified in plasma. Importantly, we also identified several cerebellar metabolites (e.g. choline, adenosine diphosphate, beta-alanine, taurine, and myo-inositol) that were sufficient to discriminate PTSD-like from resilient animals. This multilevel analysis provides a comprehensive understanding of local and systemic metabolite fingerprints associated with PTSD-like behavior, and subsequently altered brain bioenergetics. Notably, several transformed metabolic pathways observed in the cerebellum were also reflected in plasma, connecting central and peripheral biosignatures of PTSD-like behavior. These preliminary findings could direct further mechanistic studies and offer insights into potential metabolic interventions, either pharmacological or dietary, to improve PTSD resilience.

Kinetics of Muscle Carnosine Decay after β-Alanine Supplementation: A 16-wk Washout Study

PURPOSE

This study aimed to describe the kinetics of carnosine washout in human skeletal muscle over 16 wk.

METHODS

Carnosine washout kinetics were studied in 15 young, physically active omnivorous men randomly assigned to take 6.4 g·d-1 of β-alanine (n = 11) or placebo (n = 4) for 8 wk. Muscle carnosine content (M-Carn) was determined before (PRE), immediately after (POST), and 4, 8, 12, and 16 wk after supplementation. High-intensity exercise tests were performed at these same time points. Linear and exponential models were fitted to the washout data, and the leave-one-out method was used to select the model with the best fit for M-Carn decay data. Repeated-measures correlation analysis was used to assess the association between changes in M-Carn and changes in performance.

RESULTS

M-Carn increased from PRE to POST in the β-alanine group only (+91.1% ± 29.1%; placebo, +0.04% ± 10.1%; P < 0.0001). M-Carn started to decrease after cessation of β-alanine supplementation and continued to decrease until week 16 (POST4, +59% ± 40%; POST8, +35% ± 39%; POST12, +18% ± 32%; POST16, -3% ± 24% of PRE M-Carn). From week 12 onward, M-Carn was no longer statistically different from PRE. Both linear and exponential models displayed very similar fit and could be used to describe carnosine washout, although the linear model presented a slightly better fit. The decay in M-Carn was mirrored by a similar decay in high-intensity exercise tolerance; M-Carn was moderately and significantly correlated with total mechanical work done (r = 0.505; P = 0.032) and time to exhaustion (r = 0.72; P < 0.001).

CONCLUSIONS

Carnosine washout takes 12-16 wk to complete, and it can be described either by linear or exponential curves. Changes in M-Carn seem to be mirrored by changes in high-intensity exercise tolerance. This information can be used to optimize β-alanine supplementation strategies.

Combining bioinformatics analysis and experiments to explore CARNS1 as a prognostic biomarker for breast cancer

BACKGROUND

Breast cancer is a heterogeneous malignant disease, which has variation in clinical behaviors. High-throughput technologies have added important genetic alternative and biological change information for breast cancer. CARNS1 is an important ATPases. It can catalyze the synthesis of carnosine, which has antiproliferative activity in cancer. Here, we hypothesize that CARNS1 plays an essential role in the development of breast cancer.

METHODS

The expressions of CARNS1 in breast cancer were data-mined and analyzed from TCGA (the Cancer Genome Atlas) and GEO (the Gene Expression Omnibus) databases. The correlation of CARNS1 expression with clinical characteristics and the diagnostic capability of CARNS1 were assessed. Experimental studies were conducted in two cohorts (n = 60) of breast cancer patients by qRT-PCR and immunohistochemical analysis.

RESULTS

CARNS1 was significantly downregulated in breast cancer. The expression was correlated with tumor molecular and histological types, T and M stages, and vital status. Kaplan-Meier survival analysis showed that the downregulation of CARNS1 was significantly related to poor overall survival and relapse-free survival. Moreover, these scenarios have been extended to ER, PR, and HER2 positive patients. Univariate and multivariate analysis showed that CARNS1 can be considered as an independent prognostic predictor for patients with breast cancer. Experimental data supported that the protein and mRNA levels of CARNS1 in breast cancer are indeed significantly downregulated.

CONCLUSION

Our findings have demonstrated that CARNS1 acts as a tumor suppressor gene and may be an independent prognostic indicator for breast cancer patients.

SIRT3 (Sirtuin-3) Prevents Ang II (Angiotensin II)-Induced Macrophage Metabolic Switch Improving Perivascular Adipose Tissue Function

OBJECTIVE

Infiltrated macrophages actively promote perivascular adipose tissue remodeling and represent a dominant population in the perivascular adipose tissue microenvironment of hypertensive mice. However, the role of macrophages in initiating metabolic inflammation remains uncertain. SIRT3 (sirtuin-3), a NAD-dependent deacetylase, is sensitive to metabolic status and mediates adaptation responses. In this study, we investigated the role of SIRT3-mediated metabolic shift in regulating NLRP3 (Nod-like receptor family pyrin domain-containing 3) inflammasome activation. Approach and Results: Here, we report that Ang II (angiotensin II) accelerates perivascular adipose tissue inflammation and fibrosis, accompanied by NLRP3 inflammasome activation and IL (interleukin)-1β secretion in myeloid SIRT3 knockout (SIRT3-/-) mice. This effect is associated with adipose tissue mitochondrial dysfunction. In vitro studies indicate that the deletion of SIRT3 in bone marrow-derived macrophages induces IL-1β production by shifting the metabolic phenotype from oxidative phosphorylation to glycolysis. Mechanistically, SIRT3 deacetylates and activates PDHA1 (pyruvate dehydrogenase E1 alpha) at lysine 83, and the loss of SIRT3 leads to PDH activity decrease and lactate accumulation. Knocking down LDHA (lactate dehydrogenase A) or using carnosine, a buffer against lactic acid, attenuates IL-1β secretion. Furthermore, the blockade of IL-1β from macrophages into brown adipocytes restores thermogenic markers and mitochondrial oxygen consumption. Moreover, NLRP3 knockout (NLRP3-/-) mice exhibited reduced IL-1β production while rescuing the mitochondrial function of brown adipocytes and alleviating perivascular adipose tissue fibrosis.

CONCLUSIONS

SIRT3 represents a potential therapeutic target to attenuate NLRP3-related inflammation. Pharmacological targeting of glycolytic metabolism may represent an effective therapeutic approach.

The effect of genotype and muscle type on the physico-chemical characteristics and taurine, carnosine and L-carnitine concentration in lamb meat

An experiment was conducted to determine the chosen bioactive components and physico-chemical characteristics of lamb meat of different animal genotypes and the muscle types. The 22 ram lambs of Polish Merino (PM) and 22 crossbreeds of Polish Merino × Berrichone du Cher (PMB) were fattened to achieve their slaughter weight of 40 kg. After slaughter, the carcasses were kept at 4 ∘C for 24 h. Then, the samples of longissimus lumborum (LL) and gluteus medius (GM) muscle were collected to analyse the physico-chemical traits; fatty acid profile; and concentrations of taurine, carnosine, L-carnitine. The GM muscle compared to LL had the higher value (P < 0.05) of L* and a lower value (P < 0.05) of b* and H* both in PM and PMB lambs. The value of expressed juice was lower (P < 0.05) in both LL and GM muscles of PM lambs. A higher amount (P < 0.05) of collagen was found in LL muscle compared to GM both in PM and PMB lambs. The GM muscle of PM lambs showed higher (P < 0.05) conjugated linoleic acid (CLA) content, as well as higher total polyunsaturated acids (PUFAs), PUFA n-6, and PUFA n-3 (P < 0.05). The GM muscle was characterized by a higher (P < 0.05) content of taurine, while in the LL muscle there was a higher amount (P < 0.05) of carnosine. A larger amount (P < 0.05) of L-carnitine was found in GM muscle but only within PMB lambs. The obtained results showed a greater impact of the lamb's genotype on the physical characteristics of meat than on its chemical composition and the content of bioactive components. The muscle type had an effect on meat colour; collagen content; fatty acid profile; and amount of taurine, carnosine, and L-carnitine present.

Reduced Dose of Beta-Alanine Is Sufficient to Maintain Performance in Repeated Sprints

Zandona, BA, Ramos, RA, de Oliveira, CdS, McAnulty, SR, Ferreira, LHB, Smolarek, AC, Enes, AAN, Urbinati, KMdSS, Aragon, AA, Schoenfeld, BJ, and de Souza Junior, TP. Reduced Dose of Beta-Alanine Is Sufficient to Maintain Performance in Repeated Sprints. J Strength Cond Res XX(X): 000-000, 2020-Beta-alanine (BA) supplementation has been shown to be effective in improving physical performance by increasing carnosine concentration. However, it is still necessary to know the effect of a maintenance dose on performance. Thus, this study aimed to investigate the effects of a maintenance dose of BA supplementation on performance. Forty-four anaerobically trained men with 23.9 ± 3.8 years of age, 176.0 ± 0.05 cm height, 81.2 ± 7.5 kg body mass, and 15.5 ± 2.9% of body fat performed a cycle ergometer test consisting of 4 sprints of 30 s with 4 minutes of active recovery. The study comprised 3 phases: (a) presupplementation, (b) supplementation with 6.4 g·d BA or placebo, and (c) postsupplementation with a maintenance dose of 1.2 g·d of BA or interruption of supplementation. Data were analyzed using generalized estimated equations with a priori 0.05 level of significance. The placebo group and interruption group presented a lower power (7.28 ± 0.66 and 7.71 ± 0.42 W·kg vs. 8.04 ± 0.84 and 9.25 ± 1.18 W·kg, respectively; p < 0.05) during the third sprint in postsupplementation, whereas the maintenance group maintained the required power (7.47 ± 1.03 vs. 8.74 ± 1.07 W·kg; p > 0.05). The placebo group also presented higher percentage of fatigue (44.5% ± 12.3 and 44.8% ± 7.7 vs. 37.6 ± 7.2%; p = 0.021) and higher subjective perception of exertion (8.92 ± 0.90 vs. 8.00 ± 1.60; p = 0.028). Therefore, the maintenance dose of 1.2 g·d BA was effective in maintaining performance, whereas a reduction in performance was observed after supplementation interruption.

Effects of Beta-Alanine Supplementation on Physical Performance in Aerobic-Anaerobic Transition Zones: A Systematic Review and Meta-Analysis

Beta-alanine supplementation (BA) has a positive impact on physical performance. However, evidence showing a benefit of this amino acid in aerobic-anaerobic transition zones is scarce and the results controversial. The aim of this systematic review and meta-analysis is to analyze the effects of BA supplementation on physical performance in aerobic-anaerobic transition zones. At the same time, the effect of different dosages and durations of BA supplementation were identified. The search was designed in accordance with the PRISMA^® guidelines for systematic reviews and meta-analyses and performed in Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2010 and 2020. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the Time Trial Test (TTT) and Time to Exhaustion (TTE) tests, the latter separated into the Limited Time Test (LTT) and Limited Distance Test (LDT). The analysis was carried out with a pooled standardized mean difference (SMD) through Hedges' g test (95% CI). Nineteen studies were included in the systematic review and meta-analysis, revealing a small effect for time in the TTT (SMD, -0.36; 95% CI, -0.87-0.16; I² = 59%; p = 0.010), a small effect for LTT (SMD, 0.25; 95% CI, -0.01-0.51; I² = 0%; p = 0.53), and a large effect for LDT (SMD, 4.27; 95% CI, -0.25-8.79; I² = 94%; p = 0.00001). BA supplementation showed small effects on physical performance in aerobic-anaerobic transition zones. Evidence on acute supplementation is scarce (one study); therefore, exploration of acute supplementation with different dosages and formats on physical performance in aerobic-anaerobic transition zones is needed.

Space Flight Diet-Induced Deficiency and Response to Gravity-Free Resistive Exercise

Immune system dysregulation is among the many adverse effects incurred by astronauts during space flights. Omega-3 fatty acids, β-alanine, and carnosine are among the many nutrients that contribute to immune system health. For space flight, crewmembers are prescribed a diet with a macronutrient composition of 55% carbohydrate, 30% fat, and 15% protein. To quantify omega-3 fatty acid, β-alanine and carnosine intakes from such a diet, and to examine each nutrient's impact on exercise performance, 21 participants adhered to the aforementioned macronutrient ratio for 14 days which was immediately followed by a workout performed on gravity-independent resistive exercise hardware. Results included daily omega-3 fatty acid intakes below the suggested dietary intake. Daily omega-3 fatty acid, β-alanine and carnosine intakes each correlated with non-significant amounts of variance from the workout's volume of work. Given the nutritional requirements to maintain immune system function and the demands of in-flight exercise countermeasures for missions of increasingly longer durations current results, in combination with previously published works, imply in-flight supplementation may be a prudent approach to help address the physiological and mental challenges incurred by astronauts on future space flights.

Replacing soybean meal with rapeseed meal and faba beans in a growing-finishing pig diet: Effect on growth performance, meat quality and metabolite changes

Rapeseed meal and faba beans (RSM/FB) can serve as an alternative to imported soybean meal (SBM). In this study, forty Norwegian crossbred ([Landrace x Yorkshire] x Duroc) growing-finishing pigs (108.7 ± 4.2 kg final BW) were fed a diet with either SBM or RSM/FB as protein sources. RSM/FB increased feed conversion ratio (P = .04) in the finishing period, reduced lightness (P = .04) and yellowness (P = .004) of meat, changed amounts of individual fatty acids, but not of total SFA, MUFA and PUFA. Importantly, RSM/FB reduced the glucose level (P < .05) in meat. Lower pyroglutamic acid (P = .06) in RSM/FB indicate lower oxidative stress in pre-rigor muscle cell. Increased abundance of free amino acids, sweet tasting metabolites, reduced warmed-over flavor and flavor attributes indicated desirable properties of RSM/FB meat. To conclude, RSM/FB in pig diet supported growth performance and carcass quality comparable to SBM and had a positive effect on meat quality.

Beta alanine supplementation effects on metabolic contribution and swimming performance

BACKGROUND

Investigations of β-alanine supplementation shows effects on metabolic (aerobic and anaerobic) participation and performance on swimming by a possible blood acidosis buffering. Considering this background, the objective of the present study was to analyze the effects of β-alanine supplementation on metabolic contribution and performance during 400-m swim.

METHODS

Thirteen competitive swimmers underwent a 6-week, double-blind placebo-controlled study, ingesting 4.8 g.day- 1 of β-alanine or placebo. Before and after the supplementation period, the total anaerobic contribution (TAn) and 30-s all-out tethered swimming effort (30TS) were assessed. Anaerobic alactic (AnAl) and lactic energy (AnLa) was assumed as the fast component of excess post-exercise oxygen consumption and net blood lactate accumulation during exercise (∆[La-]), respectively. Aerobic contribution (Aer) was determined by the difference between total energy demand and TAn. In addition to conventional statistical analysis (Repeated measures ANOVA; p > 0.05), a Bayesian repeated measures ANOVA was used to evidence the effect probability (BFincl).

RESULTS

No differences and effects were found between groups, indicating no supplementation effects. Repeated measures ANOVA, with confirmation of effect, was indicate reduce in ∆Lactate (p: 0.001; BFincl: 25.02); absolute AnLa (p: 0.002; BFincl: 12.61), fatigue index (p > 0.001; BFincl: 63.25) and total anaerobic participation (p: 0.008; BFincl: 4.89).

CONCLUSIONS

Thus, the results demonstrated that all changes presented were evidenced as a result of exposure to the training period and β-alanine supplementation doesn't affect metabolic contribution and performance during 400-m freestyle.

GADL1 is a multifunctional decarboxylase with tissue-specific roles in β-alanine and carnosine production

Carnosine and related β-alanine-containing peptides are believed to be important antioxidants, pH buffers, and neuromodulators. However, their biosynthetic routes and therapeutic potential are still being debated. This study describes the first animal model lacking the enzyme glutamic acid decarboxylase-like 1 (GADL1). We show that Gadl1^-/- mice are deficient in β-alanine, carnosine, and anserine, particularly in the olfactory bulb, cerebral cortex, and skeletal muscle. Gadl1^-/- mice also exhibited decreased anxiety, increased levels of oxidative stress markers, alterations in energy and lipid metabolism, and age-related changes. Examination of the GADL1 active site indicated that the enzyme may have multiple physiological substrates, including aspartate and cysteine sulfinic acid. Human genetic studies show strong associations of the GADL1 locus with plasma levels of carnosine, subjective well-being, and muscle strength. Together, this shows the multifaceted and organ-specific roles of carnosine peptides and establishes Gadl1 knockout mice as a versatile model to explore carnosine biology and its therapeutic potential.

Insulin does not stimulate β-alanine transport into human skeletal muscle

To test whether high circulating insulin concentrations influence the transport of β-alanine into skeletal muscle at either saturating or subsaturating β-alanine concentrations, we conducted two experiments whereby β-alanine and insulin concentrations were controlled. In experiment 1, 12 men received supraphysiological amounts of β-alanine intravenously (0.11 g·kg−1·min−1for 150 min), with or without insulin infusion. β-Alanine and carnosine were measured in muscle before and 30 min after infusion. Blood samples were taken throughout the infusion protocol for plasma insulin and β-alanine analyses. β-Alanine content in 24-h urine was assessed. In experiment 2, six men ingested typical doses of β-alanine (10 mg/kg) before insulin infusion or no infusion. β-Alanine was assessed in muscle before and 120 min following ingestion. In experiment 1, no differences between conditions were shown for plasma β-alanine, muscle β-alanine, muscle carnosine and urinary β-alanine concentrations (all P > 0.05). In experiment 2, no differences between conditions were shown for plasma β-alanine or muscle β-alanine concentrations (all P > 0.05). Hyperinsulinemia did not increase β-alanine uptake by skeletal muscle cells, neither when substrate concentrations exceed the Vmaxof β-alanine transporter TauT nor when it was below saturation. These results suggest that increasing insulin concentration is not necessary to maximize β-alanine transport into muscle following β-alanine intake.

Nutraceutical support in heart failure: a position paper of the International Lipid Expert Panel (ILEP)

Heart failure (HF) is a complex clinical syndrome that represents a major cause of morbidity and mortality in Western countries. Several nutraceuticals have shown interesting clinical results in HF prevention as well as in the treatment of the early stages of the disease, alone or in combination with pharmacological therapy. The aim of the present expert opinion position paper is to summarise the available clinical evidence on the role of phytochemicals in HF prevention and/or treatment that might be considered in those patients not treated optimally as well as in those with low therapy adherence. The level of evidence and the strength of recommendation of particular HF treatment options were weighed up and graded according to predefined scales. A systematic search strategy was developed to identify trials in PubMed (January 1970 to June 2019). The terms 'nutraceuticals', 'dietary supplements', 'herbal drug' and 'heart failure' or 'left verntricular dysfunction' were used in the literature search. The experts discussed and agreed on the recommendation levels. Available clinical trials reported that the intake of some nutraceuticals (hawthorn, coenzyme Q10, l-carnitine, d-ribose, carnosine, vitamin D, probiotics, n-3 PUFA and beet nitrates) might be associated with improvements in self-perceived quality of life and/or functional parameters such as left ventricular ejection fraction, stroke volume and cardiac output in HF patients, with minimal or no side effects. Those benefits tended to be greater in earlier HF stages. Available clinical evidence supports the usefulness of supplementation with some nutraceuticals to improve HF management in addition to evidence-based pharmacological therapy.

Protein Engineering of a Pyridoxal-5'-Phosphate-Dependent l-Aspartate-α-Decarboxylase from Tribolium castaneum for β-Alanine Production

In the present study, a pyridoxal-5′-phosphate (PLP)-dependent L-aspartate-α-decarboxylase from Tribolium castaneum (TcPanD) was selected for protein engineering to efficiently produce β-alanine. A mutant TcPanD-R98H/K305S with a 2.45-fold higher activity than the wide type was selected through error-prone PCR, site-saturation mutagenesis, and 96-well plate screening technologies. The characterization of purified enzyme TcPanD-R98H/K305S showed that the optimal cofactor PLP concentration, temperature, and pH were 0.04% (m/v), 50 °C, and 7.0, respectively. The 1mM of Na⁺, Ni²⁺, Co²⁺, K⁺, and Ca²⁺ stimulated the activity of TcPanD-R98H/K305S, while only 5 mM of Ni²⁺ and Na⁺ could increase its activity. The kinetic analysis indicated that TcPanD-R98H/K305S had a higher substrate affinity and enzymatic reaction rate than the wild enzyme. A total of 267 g/L substrate l-aspartic acid was consumed and 170.5 g/L of β-alanine with a molar conversion of 95.5% was obtained under the optimal condition and 5-L reactor fermentation.

The evolution of dermal shield vascularization in Testudinata and Pseudosuchia: phylogenetic constraints versus ecophysiological adaptations

Studies on living turtles have demonstrated that shells are involved in the resistance to hypoxia during apnea via bone acidosis buffering; a process which is complemented with cutaneous respiration, transpharyngeal and cloacal gas exchanges in the soft-shell turtles. Bone acidosis buffering during apnea has also been identified in crocodylian osteoderms, which are also known to employ heat transfer when basking. Although diverse, many of these functions rely on one common trait: the vascularization of the dermal shield. Here, we test whether the above ecophysiological functions played an adaptive role in the evolutionary transitions between land and aquatic environments in both Pseudosuchia and Testudinata. To do so, we measured the bone porosity as a proxy for vascular density in a set of dermal plates before performing phylogenetic comparative analyses. For both lineages, the dermal plate porosity obviously varies depending on the animal lifestyle, but these variations prove to be highly driven by phylogenetic relationships. We argue that the complexity of multi-functional roles of the post-cranial dermal skeleton in both Pseudosuchia and Testudinata probably is the reason for a lack of obvious physiological signal, and we discuss the role of the dermal shield vascularization in the evolution of these groups. This article is part of the theme issue 'Vertebrate palaeophysiology'.

Modulation of Pro-Oxidant and Pro-Inflammatory Activities of M1 Macrophages by the Natural Dipeptide Carnosine

Carnosine is a natural endogenous dipeptide widely distributed in mammalian tissues, existing at particularly high concentrations in the muscles and brain and possesses well-characterized antioxidant and anti-inflammatory activities. In an in vitro model of macrophage activation, induced by lipopolysaccharide + interferon-gamma (LPS + IFN-γ), we here report the ability of carnosine to modulate pro-oxidant and pro-inflammatory activities of macrophages, representing the primary cell type that is activated as a part of the immune response. An ample set of parameters aimed to evaluate cytotoxicity (MTT assay), energy metabolism (HPLC), gene expressions (high-throughput real-time PCR (qRT-PCR)), protein expressions (western blot) and nitric oxide production (qRT-PCR and HPLC), was used to assess the effects of carnosine on activated macrophages challenged with a non cytotoxic LPS (100 ng/mL) + IFN-γ (600 U/mL) concentration. In our experimental model, main carnosine beneficial effects were: (1) the modulation of nitric oxide production and metabolism; (2) the amelioration of the macrophage energy state; (3) the decrease of the expressions of pro-oxidant enzymes (Nox-2, Cox-2) and of the lipid peroxidation product malondialdehyde; (4) the restoration and/or increase of the expressions of antioxidant enzymes (Gpx1, SOD-2 and Cat); (5) the increase of the transforming growth factor-β1 (TGF-β1) and the down-regulation of the expressions of interleukins 1β and 6 (IL-1β and IL-6) and 6) the increase of the expressions of Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1). According to these results carnosine is worth being tested in the treatment of diseases characterized by elevated levels of oxidative stress and inflammation (atherosclerosis, cancer, depression, metabolic syndrome, and neurodegenerative diseases).