BACKGROUND: Aging is a progressive process characterized by weakness in brain function. Although metabolomics studies on the brain related with aging have been conducted, it is not yet fully understood. A systematic metabolomics study was performed to search for biomarkers and monitor altered metabolism in various brain tissues of the cortex, cerebellum, hypothalamus, and hippocampus of young (8 months old) and old rats (22 months old).
METHODS: Simultaneous profiling analysis of amino acids (AAs), organic acids (OAs), and fatty acids (FAs) in the brain tissues of young and old rats were performed by gas chromatography-tandem mass spectrometry.
RESULTS: Under optimal conditions, AA, OA, and FA profiling methods showed good linearity (r ≥0.995) with limit of detection of ≤30 and 73.2 ng and limit of quantification of ≤90.1 and 219.5 ng, respectively. Repeatability varied from 0.4 to 10.4 and 0.8 to 14.8% relative standard deviation and accuracy varied from -11.3 to 10.3 and -12.8 to 14.1% relative error, respectively. In the profiling analysis, total 32, 43, 45, and 30 metabolites were determined in cortex, cerebellum, hypothalamus, and hippocampus, respectively. In statistical analysis, eight AAs (alanine, valine, leucine, isoleucine, threonine, serine, proline, and phenylalanine) in the cortex and four metabolites (alanine, phenylalanine, 3-hydoxypropionic acid, and eicosadienoic acid) in the cerebellum were significantly evaluated (Q-value <0.05, variable importance in projection scores ≥1.0). In all brain tissues, the score plots of orthogonal partial least square discriminant analysis were clearly separated between the young and old groups.
CONCLUSIONS: Metabolomics results indicate that mechanistic targets of rapamycin complex 1, branched chain-amino acid, and energy metabolism are related to inflammation and mitochondrial dysfunction in the brain during aging. Thus, these results may explain the characteristic metabolism of brain aging.

UNASSIGNED: d-alanine administration prevented kidney damage in a murine acute kidney injury model. Further data are needed on the influence of d-alanine on kidney function in humans.
UNASSIGNED: This study investigated the effects of d-alanine intake on amino acid metabolism and kidney function in healthy volunteers.
UNASSIGNED: This multicenter pilot study randomly assigned individuals from the general Japanese population to receive 3 g or 6 g of d-alanine intake per day for 7 d in a 1:1 ratio. The primary endpoint was the mean change in plasma and urine d-alanine levels from baseline to 7 d after intake. The secondary endpoints were mean changes in kidney function and other clinical factors. Safety was assessed by evaluating adverse events and clinical parameters.
UNASSIGNED: We randomly assigned 24 participants to the 3-g (n = 12) and 6-g d-alanine (n = 12) groups. The mean baseline estimated glomerular filtration rate (eGFR) was 73 mL/min/1.73 m2. The mean plasma d-alanine concentration increased from baseline by 77.5 ± 34.3 and 192.1 ± 80.9 nmol/mL in the 3-g and 6-g d-alanine groups (both p < 0.0001), respectively, in a dose-dependent manner (between-group difference: 114.6 nmol/mL; 95% CI: 62.1-167.2; P = 0.0002). A similar increase was observed for the urine d-alanine to creatinine ratio. The mean eGFR was elevated by 5.7 ± 8.8 mL/min/1.73 m2 in the 6-g d-alanine group (P = 0.045) but did not significantly change in the 3-g d-alanine group. Nonserious adverse events were reported in 11 participants.
UNASSIGNED: d-alanine intake increased plasma and urine d-alanine levels and was well tolerated in participants with normal kidney function. These results will be useful in future trials investigating the effects of d-alanine intake on kidney disease progression in patients with chronic kidney disease.This trial was registered at the UMIN Clinical Trials Registry as UMIN000051466.

BACKGROUND: In humans, intraduodenal infusion of L-tryptophan (Trp) increases plasma concentrations of gastrointestinal hormones and stimulates pyloric pressures, both key determinants of gastric emptying and associated with potent suppression of energy intake. The stimulation of gastrointestinal hormones by Trp has been shown, in preclinical studies, to be enhanced by extracellular calcium and mediated in part by the calcium-sensing receptor.
OBJECTIVE: This study aim was to determine whether intraduodenal calcium can enhance the effects of Trp to stimulate gastrointestinal hormones and pyloric pressures and, if so, whether it is associated with greater suppression of energy intake, in healthy males.
METHODS: Fifteen males with normal weight (mean ± standard deviation; age: 26 ± 7 years; body mass index: 22 ± 2 kg/m2), received on 3 separate occasions, 150-min intraduodenal infusions of 0, 500, or 1000 mg calcium (Ca), each combined with Trp (load: 0.1 kcal/min, with submaximal energy intake-suppressant effects) from t = 75-150 min, in a randomized, double-blind, crossover study. Plasma concentrations of GI hormones [gastrin, cholecystokinin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide (GLP)-1, and peptide tyrosine-tyrosine (PYY)], and Trp and antropyloroduodenal pressures were measured throughout. Immediately postinfusions (t = 150-180 min), energy intake at a standardized buffet-style meal was quantified.
RESULTS: In response to calcium alone, both 500- and 1000-mg doses stimulated PYY, while only the 1000-mg dose stimulated GLP-1 and pyloric pressures (all P < 0.05). The 1000-mg dose also enhanced the effects of Trp to stimulate cholecystokinin and GLP-1, and both doses stimulated PYY but, surprisingly, reduced the stimulation of GIP (all P < 0.05). Both doses substantially and dose dependently enhanced the effects of Trp to suppress energy intake (Ca-0+Trp: 1108 ± 70 kcal; Ca-500+Trp: 961 ± 90 kcal; and Ca-1000+Trp: 922 ± 96 kcal; P < 0.05).
CONCLUSIONS: Intraduodenal administration of calcium enhances the effect of Trp to stimulate plasma cholecystokinin, GLP-1, and PYY and suppress energy intake in healthy males. These findings have potential implications for novel nutrient-based approaches to energy intake regulation in obesity. The trial was registered at the Australian New Zealand Clinical Trial Registry (www.anzctr.org.au) as ACTRN12620001294943).

Glioblastoma is a highly malignant brain tumor consisting of a heterogeneous cellular population. The transformed metabolism of glioblastoma cells supports their growth and division on the background of their milieu. One might hypothesize that the transformed metabolism of a primary glioblastoma could be well adapted to limitations in the variety and number of substrates imported into the brain parenchyma and present it their microenvironment. Additionally, the phenotypic heterogeneity of cancer cells could promote the variations among their metabolic capabilities regarding the utilization of available substrates and release of metabolic intermediates. With the aim to identify the putative metabolic footprint of different types of glioblastoma cells, we exploited the possibility for separation of polar and ionic molecules present in culture media or cell lysates by hydrophilic interaction liquid chromatography (HILIC). The mass spectrometry (MS) was then used to identify and quantify the eluted compounds. The introduced method allows the detection and quantification of more than 150 polar and ionic metabolites in a single run, which may be present either in culture media or cell lysates and provide data for polaromic studies within metabolomics. The method was applied to analyze the culture media and cell lysates derived from two types of glioblastoma cells, T98G and U118. The analysis revealed that even both types of glioblastoma cells share several common metabolic aspects, and they also exhibit differences in their metabolic capability. This finding agrees with the hypothesis about metabolic heterogeneity of glioblastoma cells. Furthermore, the combination of both analytical methods, HILIC-MS, provides a valuable tool for metabolomic studies based on the simultaneous identification and quantification of a wide range of polar and ionic metabolites-polaromics.

BACKGROUND: Various techniques have been employed in aesthetic medicine to combat skin aging, in particular that of the facial region. Hyaluronic acid is utilized to enhance moisture levels and extracellular matrix molecules. This study aims to histologically assess the effects of low molecular weight hyaluronic acid fragments combined with amino acids (HAAM) on facial skin rejuvenation through intradermal microinjections.
METHODS: A total of twenty women, with an average age of 45 and ranging from 35 to 64 years old, participated in the study, including 8 in menopause and 12 in the childbearing age group. Mesotherapy was used to administer HAAM to the patients. Prior to and three months after the treatment, each patient underwent small circular punch biopsies. Ultrasound examinations were conducted using B-mode, capturing 2D images in longitudinal or transverse orientations with frequencies ranging from 5 to 13 Mega-hertz (MY LAB X8, ESAOTE, Genova, Italy). A total of 60 ultrasound examinations were taken, with 30 collected before treatment and 30 after treatment.
RESULTS: The histological analysis demonstrates an increase in fibroblast activity resulting in the production of Type III reticular collagen, as well as an increased number of blood vessels and epidermal thickness. However, the analysis of ultrasound data before and after treatment showed no statistical difference in skin thickness in malar area, chin and mandibular angle.
CONCLUSIONS: Histological assessments indicate that subcutaneous infiltration of HAAM has a substantial impact on the dermis of facial skin.

In this study, changes in bioactive compound contents and the in vitro biological activity of mixed grains, including oats, sorghum, finger millet, adzuki bean, and proso millet, with eight different blending ratios were investigated. The total phenolic compounds and flavonoid contents ranged from 14.43-16.53 mg gallic acid equivalent/g extract and 1.22-5.37 mg catechin equivalent/g extract, respectively, depending on the blending ratio. The DI-8 blend (30% oats, 30% sorghum, 15% finger millet, 15% adzuki bean, and 10% proso millet) exhibited relatively higher antioxidant and anti-diabetic effects than other blending samples. The levels of twelve amino acids and eight organic acids in the grain mixes were measured. Among the twenty metabolites, malonic acid, asparagine, oxalic acid, tartaric acid, and proline were identified as key metabolites across the blending samples. Moreover, the levels of lactic acid, oxalic acid, and malonic acid, which are positively correlated with α-glucosidase inhibition activity, were considerably higher in the DI-blending samples. The results of this study suggest that the DI-8 blend could be used as a functional ingredient as it has several bioactive compounds and biological activities, including anti-diabetic activity.

Asthma is a chronic respiratory disease with one of the largest numbers of cases in the world; thus, constant investigation and technical development are needed to unravel the underlying biochemical mechanisms. In this study, we aimed to develop a nano-DESI MS method for the in vivo characterization of the cellular metabolome. Using air-liquid interface (ALI) cell layers, we studied the role of Interleukin-13 (IL-13) on differentiated lung epithelial cells acting as a lung tissue model. We demonstrate the feasibility of nano-DESI MS for the in vivo monitoring of basal-apical molecular transport, and the subsequent endogenous metabolic response, for the first time. Conserving the integrity of the ALI lung-cell layer enabled us to perform temporally resolved metabolomic characterization followed by \"bottom-up\" proteomics on the same population of cells. Metabolic remodeling was observed upon histamine and corticosteroid treatment of the IL-13-exposed lung cell monolayers, in correlation with alterations in the proteomic profile. This proof of principle study demonstrates the utility of in vivo nano-DESI MS for characterizing ALI tissue layers, and the new markers identified in our study provide a good starting point for future, larger-scale studies.

BACKGROUND: The (un)targeted analysis of endogenous compounds has gained interest in the field of forensic postmortem investigations. The blood metabolome is influenced by many factors, and postmortem specimens are considered particularly challenging due to unpredictable decomposition processes.
OBJECTIVE: This study aimed to systematically investigate the influence of the time since death on endogenous compounds and its relevance in designing postmortem metabolome studies.
METHODS: Femoral blood samples of 427 authentic postmortem cases, were collected at two time points after death (854 samples in total; t1: admission to the institute, 1.3-290 h; t2: autopsy, 11-478 h; median ∆t = 71 h). All samples were analyzed using an untargeted metabolome approach, and peak areas were determined for 38 compounds (acylcarnitines, amino acids, phospholipids, and others). Differences between t2 and t1 were assessed by Wilcoxon signed-ranked test (p < 0.05). Moreover, all samples (n = 854) were binned into time groups (6 h, 12 h, or 24 h intervals) and compared by Kruskal-Wallis/Dunn\'s multiple comparison tests (p < 0.05 each) to investigate the effect of the estimated time since death.
RESULTS: Except for serine, threonine, and PC 34:1, all tested analytes revealed statistically significant changes between t1 and t2 (highest median increase 166%). Unpaired analysis of all 854 blood samples in-between groups indicated similar results. Significant differences were typically observed between blood samples collected within the first and later than 48 h after death, respectively.
CONCLUSIONS: To improve the consistency of comprehensive data evaluation in postmortem metabolome studies, it seems advisable to only include specimens collected within the first 2 days after death.

BACKGROUND: Hypertension (HTN) is a significant global health concern associated with morbidity and mortality. Recent research has explored the potential relationship between dietary protein intake and the development of HTN. This study aims to investigate the association between dietary amino acids and the incidence of HTN.
METHODS: This nested case-control study utilized data from the Ravansar Non-Communicable Disease (RaNCD) Cohort Study. The study included 491 new HTN cases identified over a 6-year follow-up period. For each case, four controls were randomly selected through density sampling. A food frequency questionnaire (FFQ) consisting of 125 food items was used to calculate dietary amino acid intake. HTN was determined based on systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg and/or current use of antihypertensive medication in subjects without pre-existing HTN at the start of the cohort study. Conditional logistic regression was used to estimate crude and adjusted odds ratios for HTN risk.
RESULTS: The median intake of all amino acids was lower in patients with HTN compared to the control group. After adjusting for various variables in different models, the risk of developing HTN tended to increase with higher dietary amino acid intake (excluding tryptophan and acidic amino acids). Specifically, individuals in the third tertile had a higher risk of developing new HTN than those individuals in the lowest tertile, although this difference was not statistically significant (P > 0.05).
CONCLUSIONS: The findings suggest that there may be an association between increased dietary amino acid intake and the risk of developing HTN, although this association was not statistically significant in this study. Further investigations in diverse populations are needed to explore the relationship between amino acids and HTN, as well as to determine the potential positive and negative effects of specific amino acid patterns on hypertension.

BACKGROUND: Primary liver cancer (PLC) ranks third in terms of fatality rate among all malignant tumors worldwide. Proteomics and metabolomics have become widely utilized in identifying causes and diagnostic indicators of PLC. Nevertheless, in studies aiming to identify proteins/metabolites that experienced significant changes before PLC, the potential impact of reverse causation and confounding variables still needs to be fully addressed.
METHODS: This study thoroughly investigated the causal relationship between 4719 blood proteins, 21 amino acids, and the risk of PLC using the Mendelian randomization (MR) method. In addition, through a comprehensive analysis of the TCGA-LIHC cohort and GEO databases, we evaluated the differentially expressed genes (DEGs) related to serine metabolism in diagnosing and predicting the prognosis of patients with PLC.
RESULTS: A total of 63 proteins have been identified as connected to the risk of PLC. Additionally, there has been confirmation of a positive cause-effect between PLC and the concentration of serine. The integration of findings from both MR analyses determined that the protein associated with PLC risk exhibited a significant correlation with serine metabolism. Upon careful analysis of the TCGA-LIHC cohort, it was found that eight DEGs are linked to serine metabolism. After thoroughly validating the GEO database, two DEGs, TDO2 and MICB, emerged as potential biomarkers for diagnosing PLC.
CONCLUSIONS: Two proteins involved in serine metabolism, MICB and TDO2, are causally linked to the risk of PLC and could potentially be used as diagnostic indicators.