Interplay Between Plasma Glycine and Branched-Chain Amino Acids Contributes to the Development of Hypertension and Coronary Heart Disease

BACKGROUND

Higher levels of plasma glycine are linked to a reduced risk, while increased levels of total branched-chain amino acids (tBCAAs) are associated with a higher risk of essential hypertension (HTN) and coronary heart disease (CHD). As these metabolic components are interconnected, analyzing the tBCAAs/glycine ratio may help to understand their interplay in the pathogenesis of cardiovascular disease.

METHODS

The Cox regression approach was combined with the development of novel genetic tools for assessments of associations between plasma metabolomic data (glycine, tBCAAs, and tBCAAs/glycine ratio) from the UK Biobank and the development of hypertension and CHD. Genome-wide association study was performed on 186 523 White UK Biobank participants to identify new independent genetic instruments for the 2-sample Mendelian randomization analyses. P-gain statistic >10 identified instruments associated with tBCAAs/glycine ratio significantly stronger compared with individual amino acids. Outcomes of genome-wide association study on hypertension and CHD were derived from the UK Biobank (nonoverlapping sample), FinnGen, and CARDIoGRAMplusC4D.

RESULTS

The tBCAAs/glycine ratio was prospectively associated with a higher risk of developing hypertension and CHD (hazard ratio quintile, Q5 versus Q1, 1.196 [95% CI, 1.109-1.289] and 1.1226 [95% CI, 1.160-1.1296], respectively). Mendelian randomization analysis demonstrated that tBCAAs/glycine ratio (P-gain >10) was a risk factor for hypertension (meta-analyzed inverse-variance weighted causal estimate 0.45 log odds ratio/SD (95% CI, 0.26-0.64) and CHD (0.48 [95% CI, 0.29-0.67]) with an absolute effect significantly larger compared with the effect of glycine (-0.06 [95% CI, -0.1 to -0.03] and -0.08 [95% CI, -0.11 to -0.05], respectively) or tBCAAs (0.22 95% CI, 0.09-0.34] and 0.12 [95% CI, 0.01-0.24], respectively).

CONCLUSIONS

The total BCAAs/glycine ratio is a key element of the metabolic signature contributing to hypertension and CHD, which may reflect biological pathways shared by glycine and tBCAAs.

Foliar application of glycine-functionalized nanopesticides for effective prevention and control of root-knot nematodes via a targeted delivery strategy

BACKGROUND

Root-knot nematodes (RKNs) are the highly damaging pests for various crops, and the prevalence of RKNs has posed serious threats to worldwide agricultural harvest, severely affecting global food security and ecosystem health. Traditional pesticide systems on controlling RKNs generally cause environmental hazards and phytotoxicity due to the excessive use of pesticides resulted from low utilization efficiency. And effective approaches with biosafe and efficient features are highly demanded to break away from the dilemma caused by RKNs.

RESULTS

In this research, a nanopesticide system with root-targeted delivery function was developed to achieve effective prevention and control of RKNs. The nanocarriers (MSN-KH560-Gly) and the obtained nanopesticides (EB@MSN-KH560-Gly) were proved to be biosafe. Also, this nanopesticide system demonstrated sustained release behavior. The grafting of glycine (Gly) significantly improved the pesticide contents translocating to cucumber roots (about 304.7%). Besides, such root-targeted delivery function resulted in no root nodule in cucumber plants after the foliar application of these nanopesticides (prevention rate of 100%). In addition, the root nodule numbers of the infected cucumber plants decreased by 71.67%.

CONCLUSION

Foliar application of these Gly-functionalized nanopesticides achieved effective prevention and control of RKNs due to the root-targeted delivery property inherent in this nanopesticide system, and such root-targeted delivery strategy opens a novel and efficient method to protect crops from RKN invasion and thus facilitates the development of sustainable agriculture. © 2023 Society of Chemical Industry.

Effects of different dietary threonine and glycine supplies in broilers fed low-protein diets

The reduction of crude protein (CP) content of broiler diets with balanced amino acid supply can increase the nitrogen (N) utilization efficiency and reduce ammonia emission, the risk of many health problems in birds. Feeding low protein (LP) diets without the impairment of performance traits needs the optimized dietary levels of threonine (Thr) and the non-essential amino acid (AA) glycine (Gly) and serine (Ser). However, the required concentrations and interactions of Thr and Gly + Ser, expressed as Gly equivalent (Glyequi), in LP diets are not fully understood. Therefore, the aim of this study was to investigate the effects of three LP (LP1-3) grower (11-24 days) and finisher (25-35 days) diets with 2% CP reduction compared to the control (C), differing in standardized ileal digestible (SID) Thr to lysine (Lys) ratio (C, LP1, LP3: 63%, LP2: 72%) and Glyequi levels (C: 15.65 g/kg, LP1: 13.74 g/kg, LP2: 13.70 g/kg, LP3: 15.77). The LP treatments did not impair the performance traits of broilers. The LP2 treatment with increased SID Thr-to-Lys ratio (+9.0%) resulted in significantly higher body weight gain and a more advantageous feed conversion ratio in the whole fattening compared to the control treatment with normal CP level (p < 0.05). The LP3 treatment containing swine meat meal with similar Glyequi levels compared to the normal CP treatment led to the most advantageous feed conversion ratio in the finisher phase and the highest nitrogen retention efficiency (p < 0.05). However, the LP3 treatment with a high starch-to-CP ratio negatively influenced the relative carcass weight and the ratio of abdominal fat of broilers (p < 0.05).

Boron Facilitates Amelioration of Hepatic Injury by the Osmolyte Glycine and Resolves Injury by Improving the Tissue Redox Homeostasis

Background: Glycine is a conditional non-essential amino acid in human and other mammals. It is abundant in the liver and is known for a wide spectrum of characteristics including the antioxidant, antiinflammatory, immunomodulatory, and cryoprotective effects. The amino acid is a naturally occurring osmolyte compatible with protein surface interactions and has been reported in literature as a potent therapeutic immuno-nutrient for liver diseases such as alcoholic liver disease. Oral glycine administration protects ethanol-induced liver injury, improves serum and tissue lipid profile, and alleviates hepatic injury in various conditions. In recent years, sodium salt of boron (borax) has been reported for its beneficial effects on cellular stress, including the effects on cell survival, immunity, and tissue redox state. Incidentally both glycine and boron prevent apoptosis and promote cell survival under stress. Objective: This study investigates the beneficial effect of borax on liver protection by glycine. Methods: Briefly, liver toxicity was induced in rats by a single intraperitoneal injection of thioacetamide (400 mg/kg b. wt.). Results: Significant changes in oxidative stress and liver function test parameters, the molybdenum Fe-S flavin hydroxylase activity, nitric oxide and tissue histopathology were observed in thioacetamide treated positive control group. The changes were ameliorated both by glycine as well as borax, but the combinatorial treatment yielded a better response indicating the impact of boron supplementation on glycine mediated protection of liver injury in experimental animal model. Conclusions: The study has clinical implications as the hepatotoxicity caused by thioacetamide mimics features of hepatitis C infection in human.

Partly Substituting Whey for Collagen Peptide Supplementation Improves Neither Indices of Muscle Damage Nor Recovery of Functional Capacity During Eccentric Exercise Training in Fit Males

Previous studies showed that collagen peptide supplementation along with resistance exercise enhance muscular recovery and function. Yet, the efficacy of collagen peptide supplementation in addition to standard nutritional practices in athletes remains unclear. Therefore, the objective of the study was to compare the effects of combined collagen peptide (20 g) and whey protein (25 g) supplementation with a similar daily protein dose (45 g) of whey protein alone on indices of muscle damage and recovery of muscular performance during eccentric exercise training. Young fit males participated in a 3-week training period involving unilateral eccentric exercises for the knee extensors. According to a double-blind, randomized, parallel-group design, before and after training, they received either whey protein (n = 11) or whey protein + collagen peptides (n = 11). Forty-eight hours after the first training session, maximal voluntary isometric and dynamic contraction of the knee extensors were transiently impaired by ∼10% (Ptime < .001) in whey protein and whey protein + collagen peptides, while creatine kinase levels were doubled in both groups (Ptime < .01). Furthermore, the training intervention improved countermovement jump performance and maximal voluntary dynamic contraction by respectively 8% and 10% (Ptime < .01) and increased serum procollagen type 1N-terminal peptide concentration by 10% (Ptime < .01). However, no differences were found for any of the outcomes between whey and whey protein + collagen peptides. In conclusion, substituting a portion of whey protein for collagen peptide, within a similar total protein dose, improved neither indices of eccentric muscle damage nor functional outcomes during eccentric training.

Alanine to glycine ratio is a novel predictive biomarker for type 2 diabetes mellitus

AIM

We aimed to evaluate the metabolite ratios that could predict the clinical incidence or remission of type 2 diabetes mellitus (T2D).

METHODS

The Cox proportional hazards regression model was used to assess 1813 individuals without T2D to test the predictive value of metabolite ratios for T2D incidence and 451 newly diagnosed T2D for remission. The receiver operating characteristic curve analysis was performed to determine the best cut-off values for the metabolite ratios. Survival analyses were performed to compare the four subgroups defined by baseline metabolite ratios and clinical status of obesity.

RESULTS

The alanine/glycine was the most significant marker for T2D incidence (hazard ratio per SD: 1.24; p < .001). On the other hand, metabolite hydroxy sphingomyelin C22:2 was most specific for T2D remission (hazard ratio per SD: 1.32; p = .029). Survival analysis of T2D incidence among the subgroups defined by the combination of alanine/glycine and obesity showed the group with a high alanine/glycine and obesity had the highest risk of T2D incidence (p < .001). The alanine/glycine as a T2D risk marker was also validated in the independent external data.

CONCLUSIONS

The combination of obesity and the alanine/glycine ratio can be used to evaluate the diabetes risk.

Interfacial Polarization Locked Flexible β-Phase Glycine/Nb2 CTx Piezoelectric Nanofibers

Biomolecular piezoelectric materials show great potential in the field of wearable and implantable biomedical devices. Here, a self-assemble approach is developed to fabricating flexible β-glycine piezoelectric nanofibers with interfacial polarization locked aligned crystal domains induced by Nb2 CTx nanosheets. Acted as an effective nucleating agent, Nb2 CTx nanosheets can induce glycine to crystallize from edges toward flat surfaces on its 2D crystal plane and form a distinctive eutectic structure within the nanoconfined space. The interfacial polarization locking formed between O atom on glycine and Nb atom on Nb2 CTx is essential to align the β-glycine crystal domains with (001) crystal plane intensity extremely improved. This β-phase glycine/Nb2 CTx nanofibers (Gly-Nb2 C-NFs) exhibit fabulous mechanical flexibility with Young's modulus of 10 MPa, and an enhanced piezoelectric coefficient of 5.0 pC N-1 or piezoelectric voltage coefficient of 129 × 10-3 Vm N-1 . The interface polarization locking greatly improves the thermostability of β-glycine before melting (≈210°C). A piezoelectric sensor based on this Gly-Nb2 C-NFs is used for micro-vibration sensing in vivo in mice and exhibits excellent sensing ability. This strategy provides an effective approach for the regular crystallization modulation for glycine crystals, opening a new avenue toward the design of piezoelectric biomolecular materials induced by 2D materials.

Antimicrobial Activity of Glycine Air Polishing: A Clinical Split- Mouth Study on Full-Arch Implant-Supported Rehabilitations

PURPOSE

To investigate the possible antimicrobial activity of glycine air polishing by comparing peri-implant microbiota before and after treatment.

MATERIALS AND METHODS

A total of 15 patients who received implant-supported full-arch fixed rehabilitations were included. After prosthesis removal (T0), Plaque Index (PI), probing depth (PD), and bleeding on probing (BOP) were recorded. In each hemiarch, the implant with the highest PD score was selected for microbiologic sample collection from the peri-implant sulcus (T0). All patients received two different hygienic protocols (randomly administered, one per each hemiarch): glycine air-polishing (G) and cleansing with cotton pellets soaked in saline (C). At 7 days (T1) and 3 months (T2) after the intervention, PI and BOP were recorded, and new microbiologic samples were taken. Traditional polymerase chain reaction (PCR) and quantitative PCR real-time were employed for microbiologic analysis to investigate how the presence of different bacterial species varied according to the hygienic treatment performed.

RESULTS

Treatment G provided a significantly higher PI score reduction around implants compared to treatment C (P = .015). No statistical difference was found in the microbial population around G and C implant sites, with Tannerella forsythia being the most commonly detected bacterial species in both G and C groups. No statistical differences were found between the antimicrobial activity of treatments C and G.

CONCLUSIONS

Glycine powder air polishing is a valid method for professional hygienic care of implants and was more effective in PI reduction compared to the control treatment. However, its antimicrobial efficacy cannot be confirmed by the outcomes of the present study.

Sustainable Soil Additives for Water and Micronutrient Supply: Swelling and Chelating Properties of Polyaspartic Acid Hydrogels Utilizing Newly Developed Crosslinkers

Drought and water shortage are serious problems in many arid and semi-arid regions. This problem is getting worse and even continues in temperate climatic regions due to climate change. To address this problem, the use of biodegradable hydrogels is increasingly important for the application as water-retaining additives in soil. Furthermore, efficient (micro-)nutrient supply can be provided by the use of tailored hydrogels. Biodegradable polyaspartic acid (PASP) hydrogels with different available (1,6-hexamethylene diamine (HMD) and L-lysine (LYS)) and newly developed crosslinkers based on diesters of glycine (GLY) and (di-)ethylene glycol (DEG and EG, respectively) were synthesized and characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) and regarding their swelling properties (kinetic, absorbency under load (AUL)) as well as biodegradability of PASP hydrogel. Copper (II) and zinc (II), respectively, were loaded as micronutrients in two different approaches: in situ with crosslinking and subsequent loading of prepared hydrogels. The results showed successful syntheses of di-glycine-ester-based crosslinkers. Hydrogels with good water-absorbing properties were formed. Moreover, the developed crosslinking agents in combination with the specific reaction conditions resulted in higher water absorbency with increased crosslinker content used in synthesis (10% vs. 20%). The prepared hydrogels are candidates for water-storing soil additives due to the biodegradability of PASP, which is shown in an exemple. The incorporation of Cu(II) and Zn(II) ions can provide these micronutrients for plant growth.

Inhibitory effect of thiol compounds on browning precursors and intermediates in sorbitol/glycine system

BACKGROUND

Sorbitol as a sweetener is often thought to be unable to participate in the Maillard reaction causing browning. However, browning of a system was found to be significant when sorbitol was mixed with glycine and heated. The thiol compounds glutathione and cysteine were added to the system, and the inhibition mechanism of the two on the browning of the system was studied by combining the changes of precursor substances, intermediate products and browning degree.

RESULTS

When the concentration of thiol compounds reached 25 mg mL-1 , both could make the browning inhibition of the system more than 80%, and the accumulated glucose concentration was reduced to <35% of the control. The production of 3-deoxyglucosone, a precursor of melanoidin, was significantly reduced.

CONCLUSION

Glutathione and cysteine directly inhibited the production of substrates in the sorbitol/glycine system, reduced glucose accumulation through competitive consumption and captured highly active intermediates through sulfhydryl groups. This has implications for the browning control of food systems containing sugar alcohols. © 2024 Society of Chemical Industry.

Wettability of Different Zirconia Implant Surfaces after Glycine and Erythritol Treatment

PURPOSE

This in-vitro study aims to investigate whether the wettability of two zirconia implant disk surfaces is affected by glycine and erythritol air-polishing, using saline, bovine serum albumin, bovine thrombin, and bovine artificial blood as the testing mediums.

MATERIALS AND METHODS

Zirconia disks were provided by two implant companies: SDS. (Swiss Dental Solutions, Plymouth, MA, USA) (n=6) and Patent. (Zircon Medical AG, Altendorf, Switzerland) (n=6). Surface parameters (Sa, Sz, Sdr, Ssk, Sku, and Spd) were measured to determine their initial surface roughness. Air-polishing was completed using glycine or erythritol powders using the AIRFLOW. PERIO device (Manufactured by Electro Medical Systems (EMS)). The wettability of the disk surfaces was evaluated by the contact angle analysis applied on treated and untreated disks using four wetting solutions, saline, bovine serum albumin (BSA), bovine thrombin, and bovine artificial blood. In total, 720 contact angle measurements were completed with n=30 per group. Statistical analysis was performed using the one-way analysis of variance and post-hoc Tukey HSD test.

RESULTS

The results indicate SDS. has a greater wettability than Patent. before and after air-polishing. The wettability of surfaces treated with glycine was hydrophobic in some cases. Erythritol increased the surface wettability of zirconia disks compared to glycine. BSA and bovine artificial blood had lower contact angles than saline and bovine thrombin for both untreated disks.

CONCLUSIONS

The initial wettability of zirconia disks differs between manufacturers, and air-polishing with erythritol powder increases the wettability of zirconia implant disks for saline, bovine serum, bovine thrombin, and bovine artificial blood.

Construction of a Lung Adenocarcinoma Prognostic Model Utilizing Serine and Glycine Metabolism-Related Genes

The objective of this study was to construct a prognostic model by utilizing serine/glycine metabolism-related genes (SGMGs), thus establishing a risk score for lung adenocarcinoma (LUAD). Based on the TCGA-LUAD and SGMG data set, two subtypes with different SGMG expression levels were identified by clustering analysis. Thirteen differential expression genes were used to construct RiskScore by Cox regression. GSE72094 data set was used for validation. The survival characteristics, immune features, and potential benefits of chemotherapy drugs were analyzed for two risk groups. RiskScore was constructed based on the genes ABCC12, RIC3, CYP4B1, SFTPB, CACNA2D2, IGF2BP1, NTSR1, DKK1, CREG2, PITX3, RGS20, FETUB, and IGFBP1. Patients in the low-risk (LR) group exhibited a superior overall survival. In addition, aDCs, iDSs, mast cells, neutrophils, HLA, and type II IFN were more abundant in the LR group with higher IPS scores and lower TIDE scores. In contrast, NK cells, APC coinhibition, and MHC-I were more common in the high-risk (HR) group, which may be more sensitive to chemotherapy drugs such as cisplatin, oxaliplatin, and nilotinib. RiskScore was a promising biomarker that can be used to distinguish LUAD prognosis, immune features, and sensitivity to chemotherapy drugs.

The Role of Glutathione and Its Precursors in Type 2 Diabetes

Type 2 diabetes (T2D) is a major worldwide health crisis affecting about 6.2% of the world's population. Alarmingly, about one in five children in the USA have prediabetes. Glutathione (GSH) and its precursors play a promising role in the prevention and management of type T2D. Oxidative stress (OxS) is a probable factor in both T2D initiation and progression. GSH is the major cytosolic water-soluble chemical antioxidant and emerging evidence supports its role in improving T2D outcomes. Dietary supplementation with N-acetyl-cysteine (NAC) and/or glycine (GLY), which are GSH precursors, has also been studied for possible beneficial effects on T2D. This review will focus on the underlying pathophysiological and molecular mechanisms linking GSH and its precursors with T2D and OxS. In addition to their traditional antioxidant roles, the in vivo effects of GSH/NAC/GLY supplements will be evaluated for their potential abilities to modulate the complex pro-oxidant pathophysiological factors (e.g., hyperglycemia) driving T2D progression. Positive feedback loops that amplify OxS over long time intervals are likely to result in irreversible T2D micro- and macro-vascular damage. Most clinical studies with GSH/NAC/GLY have focused on adults or the elderly. Future research with pediatric populations should be a high priority since early intervention is critical.

Engineering a Novel Acetyl-CoA Pathway for Efficient Biosynthesis of Acetyl-CoA-Derived Compounds

Acetyl-CoA is an essential central metabolite in living organisms and a key precursor for various value-added products as well. However, the intracellular availability of acetyl-CoA limits the efficient production of these target products due to complex and strict regulation. Here, we proposed a new acetyl-CoA pathway, relying on two enzymes, threonine aldolase and acetaldehyde dehydrogenase (acetylating), which can convert one l-threonine into one acetyl-CoA, one glycine, and generate one NADH, without carbon loss. Introducing the acetyl-CoA pathway could increase the intracellular concentration of acetyl-CoA by 8.6-fold compared with the wild-type strain. To develop a cost-competitive and genetically stable acetyl-CoA platform strain, the new acetyl-CoA pathway, driven by the constitutive strong promoter, was integrated into the chromosome of Escherichia coli. We demonstrated the practical application of this new acetyl-CoA pathway by high titer production of β-alanine, mevalonate, and N-acetylglucosamine. At the same time, this pathway achieved a high-yield production of glycine, a value-added commodity chemical for the synthesis of glyphosate and thiamphenicol. This work shows the potential of this new acetyl-CoA pathway for the industrial production of acetyl-CoA-derived compounds.

Effect of Glycine on the Wet Carbonation of Steel Slag Used as a Cementitious Material

The wet carbonation process of steel slag (SS) is envisaged to be an effective way to sequestrate CO2 and improve the properties of SS as a supplementary cementitious material. However, the carbonation process still struggles with having a low carbonation efficiency. This paper studied the effect of glycine on the accelerated carbonation of SS. The phase composition change of carbonated SS was analyzed via XRD, FT-IR, and TG-DTG. The carbonation process of SS is facilitated by the assistance of glycine, with which the carbonation degree is increased. After 60 min of carbonation, SS with glycine obtained a CO2 sequestration rate of 9.42%. Meanwhile, the carbonation reaction could decrease the content of free calcium oxide in SS. This significantly improves the soundness of SS-cement cementitious material, and the compressive strength of cementitious materials that contain carbonated SS with glycine is improved. Additionally, the cycling performance of glycine in the successive wet carbonation process of SS was investigated. Multicycle experiments via solvent recovery demonstrated that although the promotion effect of glycine was reduced after each cycle, compared with the SS-water system, the carbonation process could still be facilitated, demonstrating that successive wet carbonation via solvent recovery has considerable potential. Herein, we provide a new idea to facilitate the wet carbonation process of SS and improve the properties of SS-cement cementitious material.

Dietary glycine supplementation enhances glutathione availability in tissues of pigs with intrauterine growth restriction

This study tested the hypothesis that dietary supplementation with glycine enhances the synthesis and concentrations of glutathione (GSH, a major antioxidant) in tissues of pigs with intrauterine growth restriction (IUGR). At weaning (21 d of age), IUGR pigs and litter mates with normal birth weights (NBW) were assigned randomly to one of two groups, representing supplementation with 1% glycine or 1.19% l-alanine (isonitrogenous control) to a corn- and soybean meal-based diet. Blood and other tissues were obtained from the pigs within 1 wk after the feeding trial ended at 188 d of age to determine GSH, oxidized GSH (GSSG), and activities of GSH-metabolic enzymes. Results indicated that concentrations of GSH + GSSG or GSH in plasma, liver, and jejunum (P < 0.001) and concentrations of GSH in longissimus lumborum and gastrocnemius muscles (P < 0.05) were lower in IUGR pigs than in NBW pigs. In contrast, IUGR increased GSSG/GSH ratios (an indicator of oxidative stress) in plasma (P < 0.001), jejunum (P < 0.001), both muscles (P < 0.05), and pancreas (P = 0.001), while decreasing activities of γ-glutamylcysteine synthetase and GSH synthetase in liver (P < 0.001) and jejunum (P < 0.01); and GSH reductase in jejunum (P < 0.01), longissimus lumborum muscle (P < 0.01), gastrocnemius muscle (P < 0.05), and pancreas (P < 0.01). In addition, IUGR pigs had greater (P < 0.001) concentrations of thiobarbituric acid reactive substances (TBARS; an indicator of lipid peroxidation) in plasma, jejunum, muscles, and pancreas than NBW pigs. Compared with isonitrogenous controls, dietary glycine supplementation increased concentrations of GSH plus GSSG and GSH in plasma (P < 0.01), liver (P < 0.001), jejunum (P < 0.001), longissimus lumborum muscle (P = 0.001), and gastrocnemius muscle (P < 0.05); activities of GSH-synthetic enzymes in liver (P < 0.01) and jejunum (P < 0.05), while reducing GSSG/GSH ratios in plasma (P < 0.001), jejunum (P < 0.001), longissimus lumborum muscle (P < 0.001), gastrocnemius muscle (P = 0.01), pancreas (P < 0.05), and kidneys (P < 0.01). Concentrations of GSH plus GSSG, GSH, and GSSG/GSH ratios in kidneys were not affected (P > 0.05) by IUGR. Furthermore, glycine supplementation reduced (P < 0.001) TBARS concentrations in plasma, jejunum, muscles, and pancreas. Collectively, IUGR reduced GSH availability and induced oxidative stress in pig tissues, and these abnormalities were prevented by dietary glycine supplementation in a tissue-specific manner.

Effect of Nutraceutical Factors on Hepatic Intermediary Metabolism in Wistar Rats with Induced Tendinopathy

Tendinopathy (TP) is a complex clinical syndrome characterized by local inflammation, pain in the affected area, and loss of performance, preceded by tendon injury. The disease develops in three phases: Inflammatory phase, proliferative phase, and remodeling phase. There are currently no proven treatments for early reversal of this type of injury. However, the metabolic pathways of the transition metabolism, which are necessary for the proper functioning of the organism, are known. These metabolic pathways can be modified by a number of external factors, such as nutritional supplements. In this study, the modulatory effect of four dietary supplements, maslinic acid (MA), hydroxytyrosol (HT), glycine, and aspartate (AA), on hepatic intermediary metabolism was observed in Wistar rats with induced tendinopathy at different stages of the disease. Induced tendinopathy in rats produces alterations in the liver intermediary metabolism. Nutraceutical treatments modify the intermediary metabolism in the different phases of tendinopathy, so AA treatment produced a decrease in carbohydrate metabolism. In lipid metabolism, MA and AA caused a decrease in lipogenesis at the tendinopathy and increased fatty acid oxidation. In protein metabolism, MA treatment increased GDH and AST activity; HT decreased ALT activity; and the AA treatment does not cause any alteration. Use of nutritional supplements of diet could help to regulate the intermediary metabolism in the TP.

Serine synthesis via reversed SHMT2 activity drives glycine depletion and acetaminophen hepatotoxicity in MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects one-third of the global population. Understanding the metabolic pathways involved can provide insights into disease progression and treatment. Untargeted metabolomics of livers from mice with early-stage steatosis uncovered decreased methylated metabolites, suggesting altered one-carbon metabolism. The levels of glycine, a central component of one-carbon metabolism, were lower in mice with hepatic steatosis, consistent with clinical evidence. Stable-isotope tracing demonstrated that increased serine synthesis from glycine via reverse serine hydroxymethyltransferase (SHMT) is the underlying cause for decreased glycine in steatotic livers. Consequently, limited glycine availability in steatotic livers impaired glutathione synthesis under acetaminophen-induced oxidative stress, enhancing acute hepatotoxicity. Glycine supplementation or hepatocyte-specific ablation of the mitochondrial SHMT2 isoform in mice with hepatic steatosis mitigated acetaminophen-induced hepatotoxicity by supporting de novo glutathione synthesis. Thus, early metabolic changes in MASLD that limit glycine availability sensitize mice to xenobiotics even at the reversible stage of this disease.

Glycine homeostasis requires reverse SHMT flux

The folate-dependent enzyme serine hydroxymethyltransferase (SHMT) reversibly converts serine into glycine and a tetrahydrofolate-bound one-carbon unit. Such one-carbon unit production plays a critical role in development, the immune system, and cancer. Using rodent models, here we show that the whole-body SHMT flux acts to net consume rather than produce glycine. Pharmacological inhibition of whole-body SHMT1/2 and genetic knockout of liver SHMT2 elevated circulating glycine levels up to eight-fold. Stable-isotope tracing revealed that the liver converts glycine to serine, which is then converted by serine dehydratase into pyruvate and burned in the tricarboxylic acid cycle. In response to diets deficient in serine and glycine, de novo biosynthetic flux was unaltered, but SHMT2- and serine-dehydratase-mediated catabolic flux was lower. Thus, glucose-derived serine synthesis is largely insensitive to systemic demand. Instead, circulating serine and glycine homeostasis is maintained through variable consumption, with liver SHMT2 a major glycine-consuming enzyme.

Poly(N-acryloylglycine-acrylamide) Hydrogel Mimics the Cellular Microenvironment and Promotes Neurite Growth with Protection from Oxidative Stress

In this work, the glycine-based acryloyl monomer is polymerized to obtain a neurogenic polymeric hydrogel for regenerative applications. The synthesized poly(N-acryloylglycine-acrylamide) [poly(NAG-b-A)] nanohydrogel exhibits high swelling (∼1500%) and is mechanically very stable, biocompatible, and proliferative in nature. The poly(NAG-b-A) nanohydrogel provides a stable 3D extracellular mimetic environment and promotes healthy neurite growth for primary cortical neurons by facilitating cellular adhesion, proliferation, actin filament stabilization, and neuronal differentiation. Furthermore, the protective role of the poly(NAG-b-A) hydrogel for the neurons in oxidative stress conditions is revealed and it is found that it is a clinically relevant material for neuronal regenerative applications, such as for promoting nerve regeneration via GSK3β inhibition. This hydrogel additionally plays an important role in modulating the biological microenvironment, either as an agonist and antagonist or as an antioxidant. Furthermore, it favors the physiological responses and eases the neurite growth efficiency. Additionally, we found out that the conversion of glycine-based acryloyl monomers into their corresponding polymer modulates the mechanical performance, mimics the cellular microenvironment, and accelerates the self-healing capability due to the responsive behavior towards reactive oxygen species (ROS). Thus, the p(NAG-b-A) hydrogel could be a potential candidate to induce neuronal regeneration since it provides a physical cue and significantly boosts neurite outgrowth and also maintains the microtubule integrity in neuronal cells.

Effect of Genetic and Dietary Perturbation of Glycine Metabolism on Atherosclerosis in Humans and Mice

Objective

Epidemiological and genetic studies have reported inverse associations between circulating glycine levels and risk of coronary artery disease (CAD). However, these findings have not been consistently observed in all studies. We sought to evaluate the causal relationship between circulating glycine levels and atherosclerosis using large-scale genetic analyses in humans and dietary supplementation experiments in mice.

Methods

Serum glycine levels were evaluated for association with prevalent and incident CAD in the UK Biobank. A multi-ancestry genome-wide association study (GWAS) meta-analysis was carried out to identify genetic determinants for circulating glycine levels, which were then used to evaluate the causal relationship between glycine and risk of CAD by Mendelian randomization (MR). A glycine feeding study was carried out with atherosclerosis-prone apolipoprotein E deficient (ApoE-/-) mice to determine the effects of increased circulating glycine levels on amino acid metabolism, metabolic traits, and aortic lesion formation.

Results

Among 105,718 subjects from the UK Biobank, elevated serum glycine levels were associated with significantly reduced risk of prevalent CAD (Quintile 5 vs. Quintile 1 OR=0.76, 95% CI 0.67-0.87; P<0.0001) and incident CAD (Quintile 5 vs. Quintile 1 HR=0.70, 95% CI 0.65-0.77; P<0.0001) in models adjusted for age, sex, ethnicity, anti-hypertensive and lipid-lowering medications, blood pressure, kidney function, and diabetes. A meta-analysis of 13 GWAS datasets (total n=230,947) identified 61 loci for circulating glycine levels, of which 26 were novel. MR analyses provided modest evidence that genetically elevated glycine levels were causally associated with reduced systolic blood pressure and risk of type 2 diabetes, but did provide evidence for an association with risk of CAD. Furthermore, glycine-supplementation in ApoE-/- mice did not alter cardiometabolic traits, inflammatory biomarkers, or development of atherosclerotic lesions.

Conclusions

Circulating glycine levels were inversely associated with risk of prevalent and incident CAD in a large population-based cohort. While substantially expanding the genetic architecture of circulating glycine levels, MR analyses and in vivo feeding studies in humans and mice, respectively, did not provide evidence that the clinical association of this amino acid with CAD represents a causal relationship, despite being associated with two correlated risk factors.

Excessive Substitution of Fish Meal with Fermented Soybean Meal Induces Oxidative Stress by Impairing Glutathione Metabolism in Largemouth Bass (Micropterus salmoides)

The application of fermented soybean meal (FSBM) is an effective strategy to alleviate the shortage of fish meal (FM) in aquaculture. However, an excessive substitution ratio often reduces fish growth and induces liver oxidative stress, while the mechanism remains poorly understood. Here, an 8-week feeding trial was conducted in largemouth bass (initial weight: 6.82 ± 0.09 g) to establish an oxidative stress model by replacing 50% of FM with FSBM (fermented by Bacillus subtilis). The results showed that FSBM substitution significantly reduced the growth performance of largemouth bass, including the weight gain rate and specific growth rate. Moreover, FSBM significantly reduced the contents of essential amino acids and total free amino acids in muscle, along with the mRNA expression of amino acids and small peptide transporters. Enzyme activity detection and liver sections showed that FSBM substitution caused liver oxidative stress, indicating the successful construction of an oxidative stress model. An integrated analysis of transcriptomic and metabolomic data revealed that FSBM substitution impaired glycine, serine and threonine metabolism, as well as glutathione metabolism. In addition, the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) was decreased in the FSBM group, which may explain the mechanism of oxidative stress caused by FSBM substitution. Considering that glycine is an important component of glutathione synthesis, key genes involved in glycine metabolism (glya, gnmt and agxt) and dietary glycine supplementation should be valued to improve the availability of FSBM. This study reveals for the first time the importance of non-essential amino acids in improving the utilization of plant-based protein sources and provides original insight for the optimization of aquatic feeds.

Vitamin B and One-Carbon Metabolite Profiles Show Divergent Associations with Cardiometabolic Risk Markers but not Cognitive Function in Older New Zealand Adults: A Secondary Analysis of the REACH Study

BACKGROUND

Vitamin B inadequacies and elevated homocysteine status have been associated with impaired cognitive and cardiometabolic health with aging. There is, however, a scarcity of research investigating integrated profiles of one-carbon (1C) metabolites in this context, including metabolites of interconnected folate, methionine, choline oxidation, and transsulfuration pathways.

OBJECTIVES

The study aimed to examine associations between vitamins B and 1C metabolites with cardiometabolic health and cognitive function in healthy older adults, including the interactive effects of Apolipoprotein E-ε4 status.

METHODS

Three hundred and thirteen healthy participants (65-74 y, 65% female) were analyzed. Vitamins B were estimated according to dietary intake (4-d food records) and biochemical status (serum folate and vitamin B12). Fasting plasma 1C metabolites were quantified by liquid chromatography with tandem mass spectrometry. Measures of cardiometabolic health included biochemical (lipid panel, blood glucose) and anthropometric markers. Cognitive function was assessed by the Computerized Mental Performance Assessment System (COMPASS) and Montreal Cognitive Assessment (MoCA). Associations were analyzed using multivariate linear (COMPASS, cardiometabolic health) and Poisson (MoCA) regression modeling.

RESULTS

Over 90% of participants met dietary recommendations for riboflavin and vitamins B6 and B12, but only 78% of males and 67% of females achieved adequate folate intakes. Higher serum folate and plasma betaine and glycine concentrations were associated with favorable cardiometabolic markers, whereas higher plasma choline and homocysteine concentrations were associated with greater cardiometabolic risk based on body mass index and serum lipids concentration values (P< 0.05). Vitamins B and homocysteine were not associated with cognitive performance in this cohort, though higher glycine concentrations were associated with better global cognitive performance (P = 0.017), episodic memory (P = 0.016), and spatial memory (P = 0.027) scores. Apolipoprotein E-ε4 status did not modify the relationship between vitamins B or 1C metabolites with cognitive function in linear regression analyses.

CONCLUSIONS

Vitamin B and 1C metabolite profiles showed divergent associations with cardiometabolic risk markers and limited associations with cognitive performance in this cohort of healthy older adults.

Magnetic ferrite nanoparticles coated with bovine serum albumin and glycine polymers for controlled release of curcumin as a model

To conquer the low water solubility and bioavailability of curcumin (CUR), to corroborate its functional qualities and to broaden its applicability in the pharmaceutical sector, numerous nanoscale methods have been widely exploited for its administration. Because of its polycystic, biodegradable, biocompatibility, non-toxicity, and non-allergenic properties, bovine serum albumin (BSA) and glycine (Gly) have been actively investigated as natural biopolymers for decades. Various BSA and Gly-based nanocarriers with unique features for CUR delivery, such as magnetic ferrite nanoparticles, are being developed (MNPs). In this work, magnesium ferrite (MgFe2O4)/BSA and nickel ferrite (NiFe2O4)/Gly nanocomposites loaded with CUR (drug model) were manufactured for the first time using a chemical co-precipitation approach to create biocompatible drug nanocarriers. It was found that the synthesized MgFe2O4/BSA and NiFe2O4/Gly nanoparticles have a uniform particle distribution and their size is much less than 100 nm. Saturation magnetization in MgFe2O4 and NiFe2O4 reaches 13.07 and 33.4 emu/g the remarkable peak of magnetization decreases to 10.99 and 32.36 emu/g after the addition of polymers. These analyses also showed the presence of chemical bonds in the structure of the nanocomposite. The curcumin diffusion process in NPs were determined using a mathematical modeling. The yielding of the product for MgFe2O4/BSA and NiFe2O4/Gly in 200 h is about 72 and 63%, respectively. Also, regressed relative diffusivities (D/R2), including effective steric hindrance, were determined as 5.75 × 10-4 and 2.72 × 10-4 h-1 for MgFe2O4/BSA and NiFe2O4/Gly, respectively. It shows that there is a significant steric barrier that significantly deviates from the molecular diffusion of the liquid. As a result, the low effective release of curcumin in the particles is more noticeable. Our study demonstrated the effective relationship between the polymer architecture and the biophysical properties of the resulting nanoparticles and shed light on new approaches for the design of efficient NP-based drug carriers.

Effect of dietary glycine supplementation on productive performance, egg quality, stress response, and fatty liver incidence in laying hens raised under heat stress conditions

The current experiment aimed to investigate the effect of dietary glycine (Gly) supplementation on productive performance, egg quality, stress response, and fatty liver incidence in laying hens raised under heat stress (HS) conditions. A total of two hundred eighty 24-wk-old Lohmann Brown-Lite laying hens were randomly allotted to 1 of 4 dietary treatments with 7 replicates. The negative control (NC) diet was prepared to meet or exceed the nutrient and energy requirement for Lohmann Brown laying hens, whereas the positive control (PC) diet was formulated to increase AMEn by 100 kcal/kg compared with the NC diet. Two additional diets were prepared by supplementing 0.341% and 0.683% Gly to the NC diet. All hens were exposed to cyclic HS at 31.4 ± 1.17°C for 8 h/d and 26.7 ± 1.10°C for the remaining time for a 12-wk trial. Results indicated that increasing supplementation of Gly in diets tended (linear, P = 0.088) to decrease the FCR of laying hens. Increasing supplementation of Gly in diets increased (linear, P < 0.05) eggshell lightness and decreased (linear, P < 0.05) egg yolk color. Moreover, a tendency for a quadratic association (P < 0.10) of serum aspartate aminotransferase and alanine aminotransferase concentrations with increasing supplementation of Gly was observed. Increasing supplementation of Gly in diets decreased (linear, P < 0.05) blood heterophil:lymphocyte ratio of laying hens. Hens fed the NC diet showed higher fatty liver incidence (P < 0.05) than those fed the PC diet, but increasing supplementation of Gly decreased (linear, P < 0.05) fatty liver incidence of laying hens. In conclusion, increasing supplementation of Gly up to 0.683% in diets decreases FCR, stress response, and fatty liver incidence in laying hens raised under HS conditions.

The collagen synthesis response to an acute bout of resistance exercise is greater when ingesting 30 g versus 15 g and 0 g hydrolyzed collagen in resistance-trained young men

BACKGROUND

Resistance exercise (RE) stimulates collagen synthesis in skeletal muscle and tendon but there is limited and equivocal evidence regarding an effect of collagen supplementation and exercise on collagen synthesis. Furthermore, it is not known if a dose-response exists regarding the effect of hydrolyzed collagen (HC) ingestion and RE on collagen synthesis.

OBJECTIVE

We aimed to determine the HC dose-response effect on collagen synthesis following high-intensity RE in resistance-trained young men.

METHODS

Using a double-blind, randomized cross-over design, 10 resistance-trained men (age: 26±3 years; height: 1.77±0.04 m; mass: 79.7±7.0 kg) ingested 0g, 15g or 30g HC with 50mg vitamin C 1h prior to performing four sets' barbell back-squat RE at 10-repetition maximum load, after which they rested for six hours. Blood samples were collected throughout each of the three interventions to analyse procollagen type Ⅰ N-terminal propeptide (PⅠNP) and β-isomerized C-terminal telopeptide of type I collagen (β-CTX) concentration, and the concentration of 18 collagen amino acids.

RESULTS

The serum PⅠNP concentration×time area-under-the-curve (AUC) was greater for 30g (267±79 μg∙L-1∙h) than 15g (235±70 μg∙L-1∙h, P=0.039) and 0g HC (219±88 μg∙L-1∙h, P=0.005) but there was no difference between 0g and 15g HC (P=0.675). The AUCs of glycine and proline were greater for 30g than for 15g and 0g HC (P<0.05). Plasma β-CTX concentration decreased from -1h to +6h (P<0.05), with no differences between interventions.

CONCLUSION

The greater PINP AUC suggests 30g HC ingested prior to high-intensity RE augments whole body collagen synthesis more than 15g and 0g HC in resistance-trained young men.

Structural and Functional Development of Inhibitory Connections from the Medial Nucleus of the Trapezoid Body to the Superior Paraolivary Nucleus

The medial nucleus of the trapezoid body (MNTB) in the auditory brainstem is the principal source of synaptic inhibition to several functionally distinct auditory nuclei. Prominent projections of individual MNTB neurons comprise the major binaural nuclei that are involved in the early processing stages of sound localization as well as the superior paraolivary nucleus (SPON), which contains monaural neurons that extract rapid changes in sound intensity to detect sound gaps and rhythmic oscillations that commonly occur in animal calls and human speech. While the processes that guide the development and refinement of MNTB axon collaterals to the binaural nuclei have become increasingly understood, little is known about the development of MNTB collaterals to the monaural SPON. In this study, we investigated the development of MNTB-SPON connections in mice of both sexes from shortly after birth to three weeks of age, which encompasses the time before and after hearing onset. Individual axon reconstructions and electrophysiological analysis of MNTB-SPON connectivity demonstrate a dramatic increase in the number of MNTB axonal boutons in the SPON before hearing onset. However, this proliferation was not accompanied by changes in the strength of MNTB-SPON connections or by changes in the structural or functional topographic precision. However, following hearing onset, the spread of single-axon boutons along the tonotopic axis increased, indicating an unexpected decrease in the tonotopic precision of the MNTB-SPON pathway. These results provide new insight into the development and organization of inhibition to SPON neurons and the regulation of developmental plasticity in diverging inhibitory pathways.SIGNIFICANCE STATEMENT The superior paraolivary nucleus (SPON) is a prominent auditory brainstem nucleus involved in the early detection of sound gaps and rhythmic oscillations. The ability of SPON neurons to fire at the offset of sound depends on strong and precise synaptic inhibition provided by glycinergic neurons in the medial nucleus of the trapezoid body (MNTB). Here, we investigated the anatomic and physiological maturation of MNTB-LSO connectivity in mice before and after the onset of hearing. We observed a period of bouton proliferation without accompanying changes in topographic precision before hearing onset. This was followed by bouton elimination and an unexpected decrease in the tonotopic precision after hearing onset. These results provide new insight into the development of inhibition to the SPON.

Glycine Enhances Oxidative Stress Tolerance and Biocontrol Efficacy of Sporidiobolus pararoseus against Aspergillus niger Decay of Apples

Apples are deeply loved by people because of their rich nutritional value, but they are susceptible to rotting. The use of antagonistic yeast is a promising method for controlling postharvest fruit diseases, but biocontrol efficacy of yeast will be weakened in environmental stress. In this study, the effects of glycine (Gly) on the oxidative stress tolerance and the biocontrol efficacy of Sporidiobolus pararoseus (S. pararoseus) against Aspergillus niger (A. niger) are discussed. Under the stimulation of H2O2, the yeast cells treated with Gly (1 mM) showed lower ROS content, less mitochondrial impairment and cellular oxidative damage, and the cell survival rate was significantly higher than Gly-untreated yeast. The yeast cells exposed to Gly significantly increased the activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and the content of glutathione (GSH). Notably, Gly-treated yeast cells had better biocontrol efficacy against A. niger in postharvest apples. The lesion diameter and decay incidence were reduced by 17.67 mm and 79.63% compared to the control, respectively, when S. pararoseus was treated with 1 mM Gly. Moreover, Gly-treated yeast increased the antioxidant enzymes activities and their gene expression were up-regulated in apples. These results indicated that 1 mM Gly not only reduced the oxidative damage of yeast, but also induced resistance-related enzymes of apples under oxidative stress, which contributed to enhancing the biocontrol efficacy of S. pararoseus against A. niger in apples.

Subgingival Use of Air-Polishing Powders: Status of Knowledge: A Systematic Review

Effective subgingival biofilm removal is crucial for achieving positive and stable outcomes in periodontal therapy, forming an indispensable part of any periodontal treatment approach. The development of air-polishing tools has emerged as a promising alternative to hand and ultrasonic scalers for dental biofilm removal. The objective of this systematic review was to assess existing literature regarding the subgingival use of various types of air-polishing powders, as an effective method of subgingival biofilm control. For this, 55 articles on this subjected were sourced from searched databases and subjected to an evaluation process of their contained information, which was subsequently structured and compiled into this manuscript. The existing literature acknowledges that good subgingival biofilm control is essential for the success of periodontal therapy, including through subgingival air-polishing, as an adjunctive procedure. This approach has the potential to enhance patient comfort during and after subgingival mechanical plaque removal, thereby mitigating damage to periodontal structures. Consequently, it may lead to improved healing capabilities within the periodontal tissues and the formation of a more stable reparative gingival junctional epithelium.

Oocyte-Specific Deletion of Slc6a9 Encoding the GLYT1 Glycine Transporter Eliminates Glycine Transport in Mouse Preimplantation Embryos and Their Ability to Counter Hypertonic Stress

Early preimplantation mouse embryos are sensitive to increased osmolarity, which can block their development. To overcome this, they accumulate organic osmolytes to maintain cell volume. The main organic osmolyte used by early mouse embryos is glycine. Glycine is transported during the mature egg and 1-cell to 4-cell embryo stages by a transporter identified as GLYT1, encoded by the Slc6a9 gene. Here, we have produced an oocyte-specific knockout of Slc6a9 by crossing mice that have a segment of the gene flanked by LoxP elements with transgenic mice expressing iCre driven by the oocyte-specific Gdf9 promoter. Slc6a9 null oocytes failed to develop glycine transport activity during meiotic maturation. However, females with these oocytes were fertile. When enclosed in their cumulus-oocyte complex, Slc6a9 null oocytes could accumulate glycine via GLYT1 transport in their coupled cumulus cells, which may support female fertility in vivo. In vitro, embryos derived from Slc6a9 null oocytes displayed a clear phenotype. While glycine rescued complete preimplantation development of wild type embryos from increased osmolarity, embryos derived from null oocytes failed to develop past the 2-cell stage even with glycine. Thus, Slc6a9 is required for glycine transport and protection against increased osmolarity in mouse eggs and early embryos.

difficile promotes virulence and spore formation, and is induced by host cathelicidin

Clostridioides difficile is a leading cause of antibiotic-associated diarrheal disease. C. difficile colonization, growth, and toxin production in the intestine is strongly associated with its ability to use amino acids to generate energy, but little is known about the impact of specific amino acids on C. difficile pathogenesis. The amino acid glycine is enriched in the dysbiotic gut and is suspected to contribute to C. difficile infection. We hypothesized that the use of glycine as an energy source contributes to colonization of the intestine and pathogenesis of C. difficile. To test this hypothesis, we deleted the glycine reductase (GR) genes grdAB, rendering C. difficile unable to ferment glycine, and investigated the impact on growth and pathogenesis. Our data show that the grd pathway promotes growth, toxin production, and sporulation. Glycine fermentation also had a significant impact on toxin production and pathogenesis of C. difficile in the hamster model of disease. Furthermore, we determined that the grd locus is regulated by host cathelicidin (LL-37) and the cathelicidin-responsive regulator, ClnR, indicating that the host peptide signals to control glycine catabolism. The induction of glycine fermentation by LL-37 demonstrates a direct link between the host immune response and the bacterial reactions of toxin production and spore formation.

Effects of Glycine Supplementation in Drinking Water on the Growth Performance, Intestinal Development, and Genes Expression in the Jejunum of Chicks

Glycine, the most basic amino acid found in nature, is considered an essential amino acid for chicks. However, the precise understanding of high concentrations of glycine's significance in promoting the growth performance of chicks, as well as its impact on intestinal development, re-mains limited. Consequently, the objective of this study was to investigate the effects of glycine supplementation in drinking water on growth performance, intestine morphology, and development in newly hatched chicks. In this study, 200 newly born chicks were selected and pro-vided with a supplementation of 0.5%, 1%, and 2% glycine in their drinking water during their first week of life. The results revealed that glycine supplementation in drinking water could significantly increase the average daily gain of chicks from days 7 to 14. Furthermore, a significant difference was observed between the group supplemented with 1% glycine and the control group. Concurrently, this glycine supplementation increased the villus height and the ratio of the villus height to crypt depth in jejunum on both day 7 and day 14. Glycine supplementation in drinking water significantly affected the mRNA expression level of the ZO-1, GCLM, and rBAT genes in jejunum, which may have certain effects on the mucosal immune defense, cellular antioxidant stress capacity, and amino acid absorption. Overall, the findings of this study indicate that glycine supplementation in drinking water can enhance the growth performance of chicks and promote their intestine development.

Chlorogenic Acid Ameliorates Post-Infectious Irritable Bowel Syndrome by Regulating Extracellular Vesicles of Gut Microbes

Post-infectious irritable bowel syndrome (PI-IBS) occurs after acute infectious diarrhea, and dysbiosis can be involved in its pathogenesis. Here, the role of chlorogenic acid (CGA) is investigated, a natural compound with several pharmacological properties, in alleviating PI-IBS in rats. It is elucidated that the gut microbiota plays a key role in PI-IBS pathogenesis and that rectal administration of CGA alleviated PI-IBS by modulating the gut microbiota and its metabolites. CGA supplementation significantly increased fecal Bacteroides acidifaciens abundance and glycine levels. Glycine structurally altered B. acidifaciens extracellular vesicles (EVs) and enriched functional proteins in the EVs; glycine-induced EVs alleviated PI-IBS by reducing inflammation and hypersensitivity of the intestinal viscera and maintaining mucosal barrier function. Moreover, B. acidifaciens EVs are enriched in the brain tissue. Thus, CGA mediates the mitigation of PI-IBS through the gut microbiota and its metabolites. This study proposes a novel mechanism of signal exchange between the gut microenvironment and the host.

Multi-omics investigation of the resistance mechanisms of pomalidomide in multiple myeloma

Background

Despite significant therapeutic advances over the last decade, multiple myeloma remains an incurable disease. Pomalidomide is the third Immunomodulatory drug that is commonly used to treat patients with relapsed/refractory multiple myeloma. However, approximately half of the patients exhibit resistance to pomalidomide treatment. While previous studies have identified Cereblon as a primary target of Immunomodulatory drugs' anti-myeloma activity, it is crucial to explore additional mechanisms that are currently less understood.

Methods

To comprehensively investigate the mechanisms of drug resistance, we conducted integrated proteomic and metabonomic analyses of 12 plasma samples from multiple myeloma patients who had varying responses to pomalidomide. Differentially expressed proteins and metabolites were screened, and were further analyzed using pathway analysis and functional correlation analysis. Also, we estimated the cellular proportions based on ssGSEA algorithm. To investigate the potential role of glycine in modulating the response of MM cells to pomalidomide, cell viability and apoptosis were analyzed.

Results

Our findings revealed a consistent decrease in the levels of complement components in the pomalidomide-resistant group. Additionally, there were significant differences in the proportion of T follicular helper cell and B cells in the resistant group. Furthermore, glycine levels were significantly decreased in pomalidomide-resistant patients, and exogenous glycine administration increased the sensitivity of MM cell lines to pomalidomide.

Conclusion

These results demonstrate distinct molecular changes in the plasma of resistant patients that could be used as potential biomarkers for identifying resistance mechanisms for pomalidomide in multiple myeloma and developing immune-related therapeutic strategies.

High productivity of immunostimulatory membrane vesicles of Limosilactobacillus antri using glycine

Nanosized membrane vesicles (MVs) released by bacteria play important roles in both bacteria-bacteria and bacteria-host interactions. Some gram-positive lactic acid bacteria produce MVs exhibiting immunoregulatory activity in the host. We found that both bacterial cells and MVs of Limosilactobacillus antri JCM 15950, isolated from the human stomach mucosa, enhance immunoglobulin A production by murine Peyer's patch cells. However, the thick cell walls of gram-positive bacteria resulted in low MV production, limiting experiments and applications using MVs. In this study, we evaluated the effects of glycine, which inhibits cell wall synthesis, on the immunostimulatory MV productivity of L. antri. Glycine inhibited bacterial growth while increasing MV production, with 20 g/L glycine increasing MV production approximately 12-fold. Glycine was most effective at increasing MV production when added in the early exponential phase, which indicated that cell division in the presence of glycine increased MV production. Finally, glycine increased MV productivity approximately 16-fold. Furthermore, glycine-induced MVs promoted interleukin-6 production by macrophage-like J774.1 cells, and the immunostimulatory activity was comparable to that of spontaneously produced MVs. Our results indicate that glycine is an effective agent for improving the production of MVs with immunostimulatory activity in gram-positive lactic acid bacteria, which can be applied as mucosal adjuvants and functional foods.

Drivers of de novo Serine/Glycine synthesis in acute leukemia

Cancer cells hijack metabolic pathways in order to provide themselves with building blocks to support their proliferation and survival. Upregulation and addiction to de novo serine/glycine synthesis is an example of metabolic rewiring in cancer cells whereby serine and glycine are synthesised via a side branch of glycolysis. In this review, we focus on upregulation of endogenous serine/glycine production in acute leukemia, namely T-cell acute leukemia (T-ALL) and acute myeloid leukemia (AML). Several genetic lesions directly driving the serine/glycine addiction in acute leukemia have been established. Additionally, indirect regulation of de novo serine/glycine synthesis is observed in acute leukemia.

Synthesis of glycine from 4-hydroxyproline in tissues of neonatal pigs with intrauterine growth restriction

This study tested the hypothesis that the synthesis of glycine from 4-hydroxyproline (an abundant amino acid in milk and neonatal blood) was impaired in tissues of piglets with intrauterine growth restriction (IUGR), thereby contributing to a severe glycine deficiency in these compromised neonates. At 0, 7, 14, and 21 days of age, IUGR piglets were euthanized, and tissues (liver, small intestine, kidney, pancreas, stomach, skeletal muscle, and heart) were obtained for metabolic studies, as well as the determination of enzymatic activities, cell-specific localization, and expression of mRNAs for glycine-synthetic enzymes. The results indicated relatively low enzymatic activities for 4-hydroxyproline oxidase (OH-POX), proline oxidase, serine hydroxymethyltransferase, threonine dehydrogenase (TDH), alanine: glyoxylate transaminase, and 4-hydroxy-2-oxoglutarate aldolase in the kidneys and liver from 0- to 21-day-old IUGR pigs, in the pancreas of 7- to 21-day-old IUGR pigs, and in the small intestine and skeletal muscle (except TDH) of 21-day-old IUGR pigs. Accordingly, the rates of conversion of 4-hydroxyproline into glycine were relatively low in tissues of IUGR piglets. The expression of mRNAs for glycine-synthetic enzymes followed the patterns of enzymatic activities and was also low. Immunohistochemical analyses revealed the relatively low abundance of OH-POX protein in the liver, kidney, and small intestine of IUGR piglets, and the lack of OH-POX zonation in their livers. These novel results provide a metabolic basis to explain why the endogenous synthesis of glycine is insufficient for optimum growth of IUGR piglets and have important implications for improving the nutrition and health of other mammalian neonates including humans with IUGR.

Diagnostic value of serum neuroactive substances in the acute exacerbation of chronic obstructive pulmonary disease complicated with depression

We aimed to investigate the potential diagnostic value of five serum neuroactive substances in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) complicated with depression. A total of 103 patients with AECOPD were enrolled between August 2020 and August 2021. All patients were assessed using a self-rating depression scale and divided into AECOPD with or without depression groups. Baseline data and serum neuroactive substance levels were compared between the two groups. Logistic regression was used to identify the risk factors. The diagnostic performance of neuroactive substances was evaluated using receiver operating characteristic (ROC) curves. Patients with AECOPD complicated with depression exhibited higher partial pressure of CO2 values and higher chronic obstructive pulmonary disease assessment test (CAT) scores. An elevated proportion of patients with more than two acute exacerbations (AEs) in the previous year was observed in this patient group (all P < 0.001). The CAT score and number of AEs during the previous year were identified as independent risk factors for AECOPD complicated with depression. No significant differences were observed in the levels of aspartic acid and glutamate between the two groups (P > 0.05). Serum γ-aminobutyric acid (GABA) and glycine (Gly) levels were decreased. In contrast, serum nitric oxide (NO) levels were increased in the AECOPD complicated with the depression group (P < 0.05). Serum GABA and Gly levels exhibited a negative correlation, and NO levels positively correlated with the number of AEs in the previous year and the CAT score. The area under the ROC curve values for GABA, Gly, and NO were 0.755, 0.695, and 0.724, respectively. Serum GABA exhibited a sensitivity of 85.1% and a specificity of 58.9%, below the cut-off value of 4855.98 nmol/L. Serum GABA, Gly, and NO may represent potential biomarkers for AECOPD complicated with depression.

Sources and Sinks of Serine in Nutrition, Health, and Disease

Amino acid dysregulation has emerged as an important driver of disease progression in various contexts. l-Serine lies at a central node of metabolism, linking carbohydrate metabolism, transamination, glycine, and folate-mediated one-carbon metabolism to protein synthesis and various downstream bioenergetic and biosynthetic pathways. l-Serine is produced locally in the brain but is sourced predominantly from glycine and one-carbon metabolism in peripheral tissues via liver and kidney metabolism. Compromised regulation or activity of l-serine synthesis and disposal occurs in the context of genetic diseases as well as chronic disease states, leading to low circulating l-serine levels and pathogenesis in the nervous system, retina, heart, and aging muscle. Dietary interventions in preclinical models modulate sensory neuropathy, retinopathy, tumor growth, and muscle regeneration. A serine tolerance test may provide a quantitative readout of l-serine homeostasis that identifies patients who may be susceptible to neuropathy or responsive to therapy.

Calcium Signaling during Cortical Apical Dendrite Initiation: A Role for Cajal-Retzius Neurons

The apical dendrite of a cortical projection neuron (CPN) is generated from the leading process of the migrating neuron as the neuron completes migration. This transformation occurs in the cortical marginal zone (MZ), a layer that contains the Cajal-Retzius neurons and their axonal projections. Cajal-Retzius neurons (CRNs) are well known for their critical role in secreting Reelin, a glycoprotein that controls dendritogenesis and cell positioning in many regions of the developing brain. In this study, we examine the possibility that CRNs in the MZ may provide additional signals to arriving CPNs, that may promote the maturation of CPNs and thus shape the development of the cortex. We use whole embryonic hemisphere explants and multiphoton microscopy to confirm that CRNs display intracellular calcium transients of <1-min duration and high amplitude during early corticogenesis. In contrast, developing CPNs do not show high-amplitude calcium transients, but instead show a steady increase in intracellular calcium that begins at the time of dendritic initiation, when the leading process of the migrating CPN is encountering the MZ. The possible existence of CRN to CPN communication was revealed by the application of veratridine, a sodium channel activator, which has been shown to preferentially stimulate more mature cells in the MZ at an early developmental time. Surprisingly, veratridine application also triggers large calcium transients in CPNs, which can be partially blocked by a cocktail of antagonists that block glutamate and glycine receptor activation. These findings outline a model in which CRN spontaneous activity triggers the release of glutamate and glycine, neurotransmitters that can trigger intracellular calcium elevations in CPNs. These elevations begin as CPNs initiate dendritogenesis and continue as waves in the post-migratory cells. Moreover, we show that the pharmacological blockade of glutamatergic signaling disrupts migration, while forced expression of a bacterial voltage-gated calcium channel (CavMr) in the migrating neurons promotes dendritic growth and migration arrest. The identification of CRN to CPN signaling during early development provides insight into the observation that many autism-linked genes encode synaptic proteins that, paradoxically, are expressed in the developing cortex well before the appearance of synapses and the establishment of functional circuits.

Novel Phenylene Lipids That Are Positive Allosteric Modulators of Glycine Receptors and Inhibitors of Glycine Transporter 2

Chronic pain is a complex condition that remains resistant to current therapeutics. We previously synthesized a series of N-acyl amino acids (NAAAs) that inhibit the glycine transporter, GlyT2, some of which are also positive allosteric modulators of glycine receptors (GlyRs). In this study, we have synthesized a library of NAAAs that contain a phenylene ring within the acyl tail with the objective of improving efficacy at both GlyT2 and GlyRs and also identifying compounds that are efficacious as dual-acting modulators to enhance glycine neurotransmission. The most efficacious positive allosteric modulator of GlyRs was 2-[8-(2-octylphenyl)octanoylamino]acetic acid (8-8 OPGly) which potentiates the EC5 for glycine activation of GlyRα1 by 1500% with an EC50 of 664 nM. Phenylene-containing NAAAs with a lysine headgroup were the most potent inhibitors of GlyT2 with (2S)-6-amino-2-[8-(3-octylphenyl)octanoylamino]hexanoic acid (8-8 MPLys) inhibiting GlyT2 with an IC50 of 32 nM. The optimal modulator across both proteins was (2S)-6-amino-2-[8-(2-octylphenyl)octanoylamino]hexanoic acid (8-8 OPLys), which inhibits GlyT2 with an IC50 of 192 nM and potentiates GlyRs by up to 335% at 1 μM. When tested in a dual GlyT2/GlyRα1 expression system, 8-8 OPLys caused the greatest reductions in the EC50 for glycine. This suggests that the synergistic effects of a dual-acting modulator cause greater enhancements in glycinergic activity compared to single-target modulators and may provide an alternate approach to the development of new non-opioid analgesics for the treatment of chronic pain.

Glycine: a long-sought novel ligand for GPR158

G-protein-coupled receptors (GPCRs) are important drug targets with chemically diverse ligands and varying intracellular coupling partners. Recent work by Laboute et al. deorphanized GPR158 as a metabotropic glycine receptor (mGlyR), thereby providing evidence of a novel neuromodulatory system involving this non-canonical Class C receptor with an impact on cognition and affective states.

Metabolomics identifies disturbances in arginine, phenylalanine, and glycine metabolism as differentiating features of exacerbating atopic asthma in children

Background

Asthma exacerbations are highly prevalent in children, but only a few studies have examined the biologic mechanisms underlying exacerbations in this population.

Objective

High-resolution metabolomics analyses were performed to understand the differences in metabolites in children with exacerbating asthma who were hospitalized in a pediatric intensive care unit for status asthmaticus. We hypothesized that compared with a similar population of stable outpatients with asthma, children with exacerbating asthma would have differing metabolite abundance patterns with distinct clustering profiles.

Methods

A total of 98 children aged 6 through 17 years with exacerbating asthma (n = 69) and stable asthma (n = 29) underwent clinical characterization procedures and submitted plasma samples for metabolomic analyses. High-confidence metabolites were retained and utilized for pathway enrichment analyses to identify the most relevant metabolic pathways that discriminated between groups.

Results

In all, 118 and 131 high-confidence metabolites were identified in positive and negative ionization mode, respectively. A total of 103 unique metabolites differed significantly between children with exacerbating asthma and children with stable asthma. In all, 8 significantly enriched pathways that were largely associated with alterations in arginine, phenylalanine, and glycine metabolism were identified. However, other metabolites and pathways of interest were also identified.

Conclusion

Metabolomic analyses identified multiple perturbed metabolites and pathways that discriminated children with exacerbating asthma who were hospitalized for status asthmaticus. These results highlight the complex biology of inflammation in children with exacerbating asthma and argue for additional studies of the metabolic determinants of asthma exacerbations in children because many of the identified metabolites of interest may be amenable to targeted interventions.

Ensemble Learning for Breast Cancer Lesion Classification: A Pilot Validation Using Correlated Spectroscopic Imaging and Diffusion-Weighted Imaging

The main objective of this work was to evaluate the application of individual and ensemble machine learning models to classify malignant and benign breast masses using features from two-dimensional (2D) correlated spectroscopy spectra extracted from five-dimensional echo-planar correlated spectroscopic imaging (5D EP-COSI) and diffusion-weighted imaging (DWI). Twenty-four different metabolite and lipid ratios with respect to diagonal fat peaks (1.4 ppm, 5.4 ppm) from 2D spectra, and water and fat peaks (4.7 ppm, 1.4 ppm) from one-dimensional non-water-suppressed (NWS) spectra were used as the features. Additionally, water fraction, fat fraction and water-to-fat ratios from NWS spectra and apparent diffusion coefficients (ADC) from DWI were included. The nine most important features were identified using recursive feature elimination, sequential forward selection and correlation analysis. XGBoost (AUC: 93.0%, Accuracy: 85.7%, F1-score: 88.9%, Precision: 88.2%, Sensitivity: 90.4%, Specificity: 84.6%) and GradientBoost (AUC: 94.3%, Accuracy: 89.3%, F1-score: 90.7%, Precision: 87.9%, Sensitivity: 94.2%, Specificity: 83.4%) were the best-performing models. Conventional biomarkers like choline, myo-Inositol, and glycine were statistically significant predictors. Key features contributing to the classification were ADC, 2D diagonal peaks at 0.9 ppm, 2.1 ppm, 3.5 ppm, and 5.4 ppm, cross peaks between 1.4 and 0.9 ppm, 4.3 and 4.1 ppm, 2.3 and 1.6 ppm, and the triglyceryl-fat cross peak. The results highlight the contribution of the 2D spectral peaks to the model, and they demonstrate the potential of 5D EP-COSI for early breast cancer detection.

Glycine: The Smallest Anti-Inflammatory Micronutrient

Glycine is a non-essential amino acid with many functions and effects. Glycine can bind to specific receptors and transporters that are expressed in many types of cells throughout an organism to exert its effects. There have been many studies focused on the anti-inflammatory effects of glycine, including its abilities to decrease pro-inflammatory cytokines and the concentration of free fatty acids, to improve the insulin response, and to mediate other changes. However, the mechanism through which glycine acts is not clear. In this review, we emphasize that glycine exerts its anti-inflammatory effects throughout the modulation of the expression of nuclear factor kappa B (NF-κB) in many cells. Although glycine is a non-essential amino acid, we highlight how dietary glycine supplementation is important in avoiding the development of chronic inflammation.

Synthesis of glycine from 4-hydroxyproline in tissues of neonatal pigs

Glycine from sow's milk only meets 20% of the requirement of suckling piglets. However, how glycine is synthesized endogenously in neonates is not known. This study determined glycine synthesis from 4-hydroxyproline (an abundant amino acid in milk and neonatal blood) in tissues of sow-reared piglets with normal birth weights. Piglets were euthanized at 0, 7, 14 and 21 days of age, and their tissues were used to determine glycine synthesis from 0 to 5 mM 4-hydroxyproline, activities and mRNA expression of key glycine-synthetic enzymes, and their cell-specific localization. Activities of 4-hydroxyproline oxidase (OH-POX), proline oxidase (POX), serine hydroxymethyltransferase (SHMT), threonine dehydrogenase (TDH), alanine:glyoxylate transaminase (AGT), and 4-hydroxy-2-oxoglutarate aldolase (HOA) occurred in the kidneys and liver from all age groups of piglets, and in the pancreas of 7- to 21-day-old piglets. Activities of OH-POX and HOA were absent from the small intestine of newborn pigs but present in the small intestine of 7- to 21-day-old piglets and in the skeletal muscle of 14- to 21-day-old piglets. Between days 0 and 21 of age, the enzymatic activities of OH-POX, AGT, and HOA decreased in the liver and kidneys but increased in the pancreas and small intestine with age. The mRNA levels of these three enzymes changed in a manner similar to their enzymatic activities. In contrast to OH-POX, AGT, and HOA, the enzymatic activities of POX, SHMT, and TDH were present in the kidneys, liver, and intestine of all age groups of piglets. Glycine was synthesized from 0.1 to 5 mM 4-hydroxyproline in the liver and kidney from 0- to 21-day-old piglets, as well as the pancreas, small intestine, and skeletal muscle from 14- to 21-day-old piglets in a concentration-dependent manner. Collectively, our findings indicate that 4-hydroxyproline is used for the synthesis of glycine in tissues of piglets to compensate for the deficiency of glycine in milk.

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

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

Customizable Resveratrol Spray-dried Micro-composites for Inhalation as a Promising Contender for Treatment of Idiopathic Pulmonary Fibrosis

The past decades have witnessed tremendous expansion in utilization of plant-derived medicines as resveratrol (RES) in treating several diseases like idiopathic pulmonary fibrosis (IPF). RES can exhibit its role in treating IPF via its outstanding antioxidant and anti-inflammatory activities. The goal of this work was to formulate RES-loaded spray-dried composite microparticles (SDCMs) suitable for pulmonary delivery via dry powder inhaler (DPI). They were prepared by spray drying of a previously prepared RES-loaded bovine serum albumin nanoparticles (BSA NPs) dispersion using different carriers. RES-loaded BSA NPs, prepared by the desolvation technique, acquired suitable particle size of 177.67±0.95 nm and entrapment efficiency of 98.7±0.35% with perfectly uniform size distribution and high stability. Considering the attributes of the pulmonary route, NPs were co-spray dried with compatible carriers viz. mannitol, dextran, trehalose, leucine, glycine, aspartic acid, and glutamic acid to fabricate SDCMs. All formulations showed suitable mass median aerodynamic diameter less than 5 µm; that is suitable for deep lung deposition. However, the best aerosolization behavior was attained from using leucine with fine particle fraction (FPF) of 75.74%, followed by glycine with FPF of 54.7%. Finally, a pharmacodynamic study was conducted on bleomycin-induced mice, and it strongly revealed the role of the optimized formulations in alleviating PF through suppressing the levels of hydroxyproline, tumor necrosis factor-α and matrix metalloproteinase-9 with obvious improvements in the treated lung histopathology. These findings indicate that in addition to leucine, the glycine amino acid, which is not commonly used yet, is very promising in the formulation of DPIs.

PAK13 and Chlorella variabilis DT025

The potential of microalgae to produce valuable compounds has garnered considerable attention. However, there are various challenges that hinder their large-scale industrial utilization, such as high production costs and the complexities associated with achieving optimal growth conditions. Therefore, we investigated the effects of glycine at different concentrations on the growth and bioactive compounds production of Synechocystis sp. PAK13 and Chlorella variabilis cultivated under nitrogen availability. Glycine supplementation resulted in increased biomass and bioactive primary metabolites accumulation in both species. Sugar production, particularly glucose content, significantly improved in Synechocystis at 3.33 mM glycine (1.4 mg/g). This led to enhanced organic acid, particularly malic acid, and amino acids production. Glycine stress also influenced the concentration of indole-3-acetic acid, which was significantly higher in both species compared to the control. Furthermore, fatty acids content increased by 2.5-fold in Synechocystis and by 1.36-fold in Chlorella. Overall, the exogenous application of glycine is a cheap, safe, and effective approach to enhancing sustainable microalgal biomass and bioproducts production.