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Acquired drug resistance is a major challenge in the management of cancer, which underscores the need for discovery and development of novel therapeutic strategies. We report here the mechanism of the anti-cancer activity of a small coordinate complex composed of the rare earth metal praseodymium (Pr) and mercaptopyridine oxide (MPO; pyrithione). Exposure of cancer cells to relatively low concentrations of the conjugate Pr-MPO (5 µM) significantly impairs cell survival in a p53-independent manner and irrespective of the drug resistant phenotype. Mechanistically, Pr-MPO-induced cell death is caspase-independent, not inhibitable by necrostatin, but associated with the appearance of autophagy markers. However, further analysis revealed incomplete autophagic flux, thus suggesting altered integrity of lysosomal machinery. Supporting the lysosomal targeting activity are data demonstrating increased lysosomal Ca2+ accumulation and alkalinization, which coincides with cytosolic acidification (drop in pHc from 7.75 to 7.00). In parallel, an increase in lysosomal activity of glycosidase alpha acid (GAA), involved in passive glycogen breakdown, correlates with rapid depletion of glucose stores upon Pr-MPO treatment. This is associated with swift cataplerosis of TCA cycle intermediates, loss of NAD+/NADH and increase in pyruvate dehydrogenase (PDH) activity to compensate for pyruvate loss. Addition of exogenous pyruvate rescued cell survival. Notably, lysosomal impairment and metabolic catastrophe triggered by Pr-MPO are suggestive of Zn2+-mediated cytotoxicity, which is confirmed by the ability of Zn2+ chelator TPEN to block Pr-MPO-mediated anti-tumor activity. Together, these results highlight the ability of the small molecule lanthanide conjugate to target the cells' waste clearing machinery as well as mitochondrial metabolism for Zn2+-mediated execution of cancer cells, which could have therapeutic potential against cancers with high metabolic activity. [ABSTRACT FROM AUTHOR]

Cataracts are a disease that reduces vision due to opacity formation of the lens. Diabetic cataracts occur at young age and progress relatively quickly, so the development of effective treatment has been awaited. Several studies have shown that pyruvate inhibits oxidative stress and glycation of lens proteins, which contribute to onset of diabetic cataracts. However, detailed molecular mechanisms have not been revealed. In this study, we attempted to reduce galactose‐induced opacity by pyruvate with rat ex vivo model. Rat lenses were extracted and cultured in galactose‐containing medium to induce lens opacity. After opacity had developed, continued culturing with pyruvate in the medium resulted in a reduction of lens opacity. Subsequently, we conducted microarray analysis to investigate the genes that contribute to the therapeutic effect. We performed quantitative expression measurements using RT‐qPCR for extracted genes that were upregulated in cataract‐induced lenses and downregulated in pyruvate‐treated lenses, resulting in the identification of 34 candidate genes. Functional analysis using the STRING database suggests that metallothionein‐related factors (Mt1a, Mt1m, and Mt2A) and epithelial‐mesenchymal transition‐related factors (Acta2, Anxa1, Cd81, Mki67, Timp1, and Tyms) contribute to the therapeutic effect of cataracts. [ABSTRACT FROM AUTHOR]

Background: The lactate/pyruvate (LP) ratio has been studied as an alternative to serum lactate to determine clinical prognosis. Despite its clinical utility, there is a paucity of evidence evaluating the role of the L/P ratio in patients with sepsis. Methods: We assessed the clinical utility of the L/P ratio in patients with sepsis. The L/P ratio was measured at baseline, 4 and 8 h after admission. Our primary outcome was to determine the prognostic utility of the L/P ratio on the 15-day mortality risk. Our secondary outcomes were to compare the L/P ratio across time and its prognostic utility against standard risk calculators such as APACHE-II and SOFA scores. Results: We had a total of 80 patients, with 18 (22.5%) survivors and 62 (77.5%) non-survivors. While we found that patients having higher L/P ratios at 8 h had an increased 30-mortality risk (OR 1.08, 95% CI 1.02–1.18), the model's performance showed no difference when compared to other measurements of the L/P ratio that showed no association with mortality (p-value: 0.45). For our secondary outcome, we found that the APACHE-II and SOFA scores have better performance and predictability than the L/P ratio (AUC 0.83 and AUC 0.80, respectively), but showed no association with mortality (OR 1.07, 95% CI 1.01–1.17 and OR 1.08, 95% CI 1.02–1.18). Conclusions: Based on our findings, the L/P ratio appears to function more effectively as an early predictor of mortality when used as an adjuvant biomarker with other clinical parameters. [ABSTRACT FROM AUTHOR]

Xanthan gum is a microbial polysaccharide produced by Xanthomonas and widely used in various industries. To produce xanthan gum, the native Xanthomonas citri- 386 was used in a cheese-whey-based culture medium. The culture conditions were investigated in batch experiments based on the response surface methodology to increase xanthan production and viscosity. Three independent variables in this study included feeding times of acetate, pyruvate, and citrate. The maximum xanthan gum production and viscosity within 120 h by X. citri -386 using Box–Behnken design were 25.7 g/l and 65   500 cP, respectively, with a 151% and 394% increase as compared to the control sample. Overall, the findings of this study recommend the use of X. citri -386 in the cheese-whey-based medium as an economical medium with optimal amounts of acetate, pyruvate, and citrate for commercial production of xanthan gum on an industrial scale. The adjustment of the pyruvate and acetate concentrations optimized xanthan gum production in the environment. [ABSTRACT FROM AUTHOR]

The present study aimed to identify the metabolites associated with the physiological activity of kimchi‐derived lactic acid bacteria (LAB). A clear difference was observed between the 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) radical scavenging rates when the pyruvate content was high (273.5 ng/µL; radical removal speed 6.50% per min) and the rates when the pyruvate content had decreased (131.9 ng/µL; radical removal speed 3.63% per min). Additionally, the characteristics of LAB antioxidant activity (increase in ABTS radical scavenging activity with reaction time, low level of 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity) were similar to those of pyruvate‐derived activity. Hydrogen peroxide content (WiKim0124, 2.08 → 0.26; WiKim0121, 0.99 → 0.47; WiKim39, 1.93 → 0.24) and lactate dehydrogenase activity (WiKim0124, 1.53 → 0.00; WiKim0121, 0.73 → 0.01; WiKim39, 1.72 → 0.02) decreased more in heat‐killed LAB than in non‐heat‐killed LAB. Accordingly, this resulted in increased pyruvate content and the inhibitory activity of lipid peroxide production increased by 2–3 times. Our findings indicate that pyruvate is one of the major metabolites regulating LAB physiological activity. Practical Application: The safety of utilizing live probiotics remains a topic of debate. To mitigate associated risks, there is a growing interest in non‐viable microorganisms or microbial cell extracts for use as probiotics. Various methods can be employed for probiotic inactivation. Heat treatment typically emerges as the preferred choice for inactivating probiotic strains in many instances. The present study shows the distinctions between inactivating lactic acid bacteria (LAB) through heat treatment and non‐heat treatment. It may serve as a valuable reference for selecting an appropriate inactivation method for LAB in industrial processes. [ABSTRACT FROM AUTHOR]

The addition of antioxidants to cryopreservation media reportedly improves sperm post‐thaw quality and reproductive performance after artificial insemination. Therefore, the objectives of this study were to evaluate if the addition of L‐carnitine and pyruvate to freezing media, or their addition to samples after thawing, improves the post‐thaw quality of equine spermatozoa. Thus, in Experiment 1, stallion semen samples were cryopreserved in: (1) EDTA–glucose–based extender with 20% egg yolk and 5% dimethylformamide (EDTA control); (2) skim milk–based extender with 20% egg yolk and 5% dimethylformamide (milk control); (3) Extender 1 supplemented with 50 mM L‐carnitine and 10 mM pyruvate (EDTA‐carnitine‐pyruvate); and (4) Extender 2 supplemented with 50 mM L‐carnitine and 10 mM pyruvate (milk‐carnitine‐pyruvate). In Experiment 2, 50 mM L‐carnitine and 10 mM pyruvate were added post‐thaw to samples cryopreserved with extenders 1 and 2 (EDTA control and milk control). Sperm kinematic parameters, DNA fragmentation, membrane lipid peroxidation, acrosome status and viability were evaluated after thawing. No significant differences (p > 0.05) were observed for most of the kinematic parameters, DNA fragmentation, membrane lipid peroxidation, acrosome status and viability of spermatozoa, between the samples frozen in the presence or absence of L‐carnitine and pyruvate, nor between the samples after the post‐thaw addition of these components. A higher (p < 0.05) mean velocity and higher (p < 0.05) amplitude of lateral head displacement were observed in the samples frozen in the milk‐based extender with the addition of L‐carnitine and pyruvate after thawing. The addition of 50 mM L‐carnitine and 10 mM pyruvate, either to the freezing extenders or after thawing, was not deleterious for sperm; however, it did not improve equine sperm motility, viability, acrosome and DNA integrity, nor decrease membrane lipid peroxidation after thawing. [ABSTRACT FROM AUTHOR]

2-Keto-3-deoxy-galactonate (KDGal) serves as a pivotal metabolic intermediate within both the fungal d-galacturonate pathway, which is integral to pectin catabolism, and the bacterial DeLey-Doudoroff pathway for d-galactose catabolism. The presence of KDGal enantiomers, l-KDGal and d-KDGal, varies across these pathways. Fungal pathways generate l-KDGal through the reduction and dehydration of d-galacturonate, whereas bacterial pathways produce d-KDGal through the oxidation and dehydration of d-galactose. Two distinct catabolic routes further metabolize KDGal: a nonphosphorolytic pathway that employs aldolase and a phosphorolytic pathway involving kinase and aldolase. Recent findings have revealed that l-KDGal, identified in the bacterial catabolism of 3,6-anhydro-l-galactose, a major component of red seaweeds, is also catabolized by Escherichia coli, which is traditionally known to be catabolized by specific fungal species, such as Trichoderma reesei. Furthermore, the potential industrial applications of KDGal and its derivatives, such as pyruvate and d- and l-glyceraldehyde, are underscored by their significant biological functions. This review comprehensively outlines the catabolism of l-KDGal and d-KDGal across different biological systems, highlights stereospecific methods for discriminating between enantiomers, and explores industrial application prospects for producing KDGal enantiomers. Key points: • KDGal is a metabolic intermediate in fungal and bacterial pathways • Stereospecific enzymes can be used to identify the enantiomeric nature of KDGal • KDGal can be used to induce pectin catabolism or produce functional materials [ABSTRACT FROM AUTHOR]

Background: Most commerce of equine seminal doses is carried out using commercial extenders under refrigeration at 5°C. Objectives: To determine if 10 mm pyruvate in a 67 mm glucose extender and storage at 22°C could be the basis of an alternative storage method to cooling to 5°C. Material and methods: Stallion ejaculates were extendedin: INRA96 (67 mm glucose, non‐pyruvate control), modified Tyrode's (67 mm glucose–10 mm pyruvate), supplemented with 0, 10, 50, and 100 μM itaconate. As itaconate was vehiculated in DMSO, a control vehicle was also included. Sperm motility, viability, mitochondrial membrane potential, and production of reactive oxygen species were measured after collection and again after 48 and 96 h of storage at 22°C. To disclose molecular metabolic changes, spermatozoa were incubated up to 3 h in modified Tyrode's 67 mm glucose–10 mm pyruvate and modified Tyrode's 67 mm glucose, and metabolic analysis conducted. Results: After 96 h of storage aliquots stored in the control, INRA96 had a very poor total motility of 5.6% ± 2.3%, while in the 67 mm glucose–10 mm pyruvate/10 μm itaconate extender, total motility was 34.7% ± 3.8% (p = 0.0066). After 96 h, viability was better in most pyruvate‐based media, and the mitochondrial membrane potential in spermatozoa extended in INRA96 was relatively lower (p < 0.0001). Metabolomics revealed that in the spermatozoa incubated in the high pyruvate media, there was an increase in the relative amounts of NAD+, pyruvate, lactate, and ATP. Discussion and conclusions: Aliquots stored in a 67 mm glucose–10 mm pyruvate‐based medium supplemented with 10 μM itaconate, maintained a 35% total motility after 96 h of storage at 22°C, which is considered the minimum acceptable motility for commercialization. Improvements may be related to the conversion of pyruvate to lactate and regeneration of NAD+. [ABSTRACT FROM AUTHOR]

Supplemental Digital Content is Available in the Text. Impairment of mitochondrial pyruvate oxidation in dorsal root ganglia is sufficient to induce long-lasting allodynia and widespread transcriptomic alterations. Metabolism is inextricably linked to every aspect of cellular function. In addition to energy production and biosynthesis, metabolism plays a crucial role in regulating signal transduction and gene expression. Altered metabolic states have been shown to maintain aberrant signaling and transcription, contributing to diseases like cancer, cardiovascular disease, and neurodegeneration. Metabolic gene polymorphisms and defects are also associated with chronic pain conditions, as are increased levels of nerve growth factor (NGF). However, the mechanisms by which NGF may modulate sensory neuron metabolism remain unclear. This study demonstrated that intraplantar NGF injection reprograms sensory neuron metabolism. Nerve growth factor suppressed mitochondrial pyruvate oxidation and enhanced lactate extrusion, requiring 24 hours to increase lactate dehydrogenase A and pyruvate dehydrogenase kinase 1 (PDHK1) expression. Inhibiting these metabolic enzymes reversed NGF-mediated effects. Remarkably, directly disrupting mitochondrial pyruvate oxidation induced severe, persistent allodynia, implicating this metabolic dysfunction in chronic pain. Nanopore long-read sequencing of poly(A) mRNA uncovered extensive transcriptomic changes upon metabolic disruption, including altered gene expression, splicing, and poly(A) tail lengths. By linking metabolic disturbance of dorsal root ganglia to transcriptome reprogramming, this study enhances our understanding of the mechanisms underlying persistent nociceptive sensitization. These findings imply that impaired mitochondrial pyruvate oxidation may drive chronic pain, possibly by impacting transcriptomic regulation. Exploring these metabolite-driven mechanisms further might reveal novel therapeutic targets for intractable pain. [ABSTRACT FROM AUTHOR]

Simple Summary: In cancer cells, gross changes in gene expression help to enhance the uptake of glucose—the blood sugar—for the increased formation of building blocks for the cancer cells' unlimited growth. An issue related to the rewired cancer cell metabolism is that even under sufficient oxygen supply, cancer cells metabolize a large fraction of the glucose to lactic acid (or "lactate"). In non-cancerous cells, lactate would be formed only during oxygen deprivation in order to re-oxidize the cytosolic electron carrier NADH, which forms during the glycolytic glucose breakdown. This phenomenon of lactate secretion from cancer cells under aerobic conditions was named the "Warburg Effect", but the actual reasons for that are often regarded as not yet understood. However, when we acknowledge that the reprogramming of the different metabolic pathways of cancer cells is not neatly fine-tuned, it becomes plausible that lactate formation just serves to dispose of cytosolic electrons that exceed the capacity of the mitochondrial electron transport chain to accept cytosolic electrons. Interestingly, the kinetic properties of the enzymes that metabolize the glycolysis end product pyruvate are sufficient to explain the priorities for metabolite flux at the pyruvate junction in cancer cells: 1. mitochondrial oxidative phosphorylation for efficient ATP production, 2. cytosolic electrons that exceed oxidative phosphorylation capacity need to be disposed of and secreted as lactate, and 3. biosynthesis reactions for cancer cell growth. In other words, a number of cytosolic electrons just take the "emergency exit" from the cell by lactate secretion to maintain the cytosolic redox balance. Cancer cells metabolize a large fraction of glucose to lactate, even under a sufficient oxygen supply. This phenomenon—the "Warburg Effect"—is often regarded as not yet understood. Cancer cells change gene expression to increase the uptake and utilization of glucose for biosynthesis pathways and glycolysis, but they do not adequately up-regulate the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS). Thereby, an increased glycolytic flux causes an increased production of cytosolic NADH. However, since the corresponding gene expression changes are not neatly fine-tuned in the cancer cells, cytosolic NAD+ must often be regenerated by loading excess electrons onto pyruvate and secreting the resulting lactate, even under sufficient oxygen supply. Interestingly, the Michaelis constants (KM values) of the enzymes at the pyruvate junction are sufficient to explain the priorities for pyruvate utilization in cancer cells: 1. mitochondrial OXPHOS for efficient ATP production, 2. electrons that exceed OXPHOS capacity need to be disposed of and secreted as lactate, and 3. biosynthesis reactions for cancer cell growth. In other words, a number of cytosolic electrons need to take the "emergency exit" from the cell by lactate secretion to maintain the cytosolic redox balance. [ABSTRACT FROM AUTHOR]

Mitochondrial alternative oxidase (AOX) is an important protein that can help in regulating reactive oxygen species and nitric oxide in plants. The role of AOX in regulation of nitro-oxidative stress in chickpea is not known. Using germinating chickpea as a model system, we investigated the role of AOX in nitro-oxidative stress tolerance. NaCl treatment was used as an inducer of nitro-oxidative stress. Treatment of germinating seeds with 150 mM NaCl led to reduced germination and radicle growth. The AOX inhibitor SHAM caused further inhibition of germination, and the AOX inducer pyruvate improved growth of the radicle under NaCl stress. Isolated mitochondria from germinated seeds under salt stress not only increased AOX capacity but also enhanced AOX protein expression. Measurement of superoxide levels revealed that AOX inhibition by SHAM can enhance superoxide levels, whereas the AOX inducer pyruvate reduced superoxide levels. Measurement of NO by gas phase chemiluminescence revealed enhanced NO generation in response to NaCl treatment. Upon NaCl treatment there was enhanced tyrosine nitration, which is an indicator of nitrosative stress response. Taken together, our results revealed that AOX induced under salinity stress in germinating chickpea can help in mitigating nitro-oxidative stress, thereby improving germination. [ABSTRACT FROM AUTHOR]

Cardiovascular disease shows, or may even be caused by, changes in metabolism. Hyperpolarized magnetic resonance spectroscopy and imaging is a technique that could assess the role of different aspects of metabolism in heart disease, allowing real-time metabolic flux assessment in vivo. In this review, we introduce the main hyperpolarization techniques. Then, we summarize the use of dedicated radiofrequency 13C coils, and report a state of the art of 13C data acquisition. Finally, this review provides an overview of the pre-clinical and clinical studies on cardiac metabolism in the healthy and diseased heart. We furthermore show what advances have been made to translate this technique into the clinic in the near future and what technical challenges still remain, such as exploring other metabolic substrates. [ABSTRACT FROM AUTHOR]

Astrocyte-derived pyruvate is considered to have neuroprotective functions. In order to investigate the processes that are involved in astrocytic pyruvate release, we used primary rat astrocyte cultures as model system. Depending on the incubation conditions and medium composition, astrocyte cultures established extracellular steady state pyruvate concentrations in the range between 150 µM and 300 µM. During incubations for up to 2 weeks in DMEM culture medium, the extracellular pyruvate concentration remained almost constant for days, while the extracellular lactate concentration increased continuously during the incubation into the millimolar concentration range as long as glucose was present. In an amino acid-free incubation buffer, glucose-fed astrocytes released pyruvate with an initial rate of around 60 nmol/(h × mg) and after around 5 h an almost constant extracellular pyruvate concentration was established that was maintained for several hours. Extracellular pyruvate accumulation was also observed, if glucose had been replaced by mannose, fructose, lactate or alanine. Glucose-fed astrocyte cultures established similar extracellular steady state concentrations of pyruvate by releasing pyruvate into pyruvate-free media or by consuming excess of extracellular pyruvate. Inhibition of the monocarboxylate transporter MCT1 by AR-C155858 lowered extracellular pyruvate accumulation, while inhibition of mitochondrial pyruvate uptake by UK5099 increased the extracellular pyruvate concentration. Finally, the presence of the uncoupler BAM15 or of the respiratory chain inhibitor antimycin A almost completely abolished extracellular pyruvate accumulation. The data presented demonstrate that cultured astrocytes establish a transient extracellular steady state concentration of pyruvate which is strongly affected by modulation of the mitochondrial pyruvate metabolism. [ABSTRACT FROM AUTHOR]

Lung branching morphogenesis relies on intricate epithelial–mesenchymal interactions and signaling networks. Still, the interplay between signaling and energy metabolism in shaping embryonic lung development remains unexplored. Retinoic acid (RA) signaling influences lung proximal–distal patterning and branching morphogenesis, but its role as a metabolic modulator is unknown. Hence, this study investigates how RA signaling affects the metabolic profile of lung branching. We performed ex vivo lung explant culture of embryonic chicken lungs treated with DMSO, 1 µM RA, or 10 µM BMS493. Extracellular metabolite consumption/production was evaluated by using 1H-NMR spectroscopy. Mitochondrial respiration and biogenesis were also analyzed. Proliferation was assessed using an EdU-based assay. The expression of crucial metabolic/signaling components was examined through Western blot, qPCR, and in situ hybridization. RA signaling stimulation redirects glucose towards pyruvate and succinate production rather than to alanine or lactate. Inhibition of RA signaling reduces lung branching, resulting in a cystic-like phenotype while promoting mitochondrial function. Here, RA signaling emerges as a regulator of tissue proliferation and lactate dehydrogenase expression. Furthermore, RA governs fatty acid metabolism through an AMPK-dependent mechanism. These findings underscore RA's pivotal role in shaping lung metabolism during branching morphogenesis, contributing to our understanding of lung development and cystic-related lung disorders. [ABSTRACT FROM AUTHOR]

Despite the significant role of pyruvic acid in biotransformations, the utilization of pyruvates in the field of catalytic asymmetric synthesis has been unexpectedly limited. This statement also applies to enamine catalysis, in which pyruvates seem to be challenging substrates. Recently, the first illustration of the asymmetric addition of pyruvic acid to β‐nitrostyrenes, catalyzed by a NahE enzyme using the enamine mechanism, has appeared in the literature. Now, we demonstrate pyrrolidine‐based catalyst can mimick enamine mechanism used by this enzyme to activate pyruvates in the asymmetric addition to structurally diverse nitroalkenes to produce highly enantioenriched Michael adducts without the limitations in substrate structures associated with biocatalysts. In addition to confirming that optically pure pyrrolidines can serve as ultimately small organic catalysts in pyruvate activation, we present an exceedingly simple and versatile method for the synthesis of optically pure γ‐nitro acids, which are precursors for well‐known active pharmaceutical ingredients namely GABA derivatives [ABSTRACT FROM AUTHOR]

If a mechanism of more efficient glycolysis depending on pyruvate is present in stallion spermatozoa, detrimental effects of higher glucose concentrations that are common in current commercial extenders could be counteracted. To test this hypothesis, spermatozoa were incubated in a 67 mM Glucose modified Tyrode's media in the presence of 1- or 10-mM pyruvate and in the Tyrode's basal media which contains 5 mM glucose. Spermatozoa incubated for 3 h at 37 °C in 67 mM Tyrode's media with 10 mM pyruvate showed increased motility in comparison with aliquots incubated in Tyrode's 5 mM glucose and Tyrode's 67 mM glucose (57.1 ± 3.5 and 58.1 ± 1.9 to 73.0 ± 1.1 %; P < 0.01). Spermatozoa incubated in Tyrode's with 67 mM glucose 10 mM pyruvate maintained the viability along the incubation (64.03 ± 15.4 vs 61.3 ± 10.2), while spermatozoa incubated in 67 mM Glucose-Tyrode's showed a decrease in viability (38.01 ± 11.2, P < 0.01). 40 mM oxamate, an inhibitor of the lactate dehydrogenase LDH, reduced sperm viability (P < 0.05, from 76 ± 5 in 67 mM Glucose/10 mM pyruvate to 68.0 ± 4.3 %, P < 0.05). Apoptotic markers increased in the presence of oxamate. (P < 0.01). UHPLC/MS/MS showed that 10 mM pyruvate increased pyruvate, lactate, ATP and NAD+ while phosphoenolpyruvate decreased. The mechanisms that explain the improvement of in presence of 10 mM pyruvate involve the conversion of lactate to pyruvate and increased NAD+ enhancing the efficiency of the glycolysis. • 10 mM pyruvate in a 67 mM Glucose-Tyrode's media maintains sperm functionality in comparison with a 67 mM glucose- Tyrode's. • Motility, linear motility, velocities membrane integrity, mitochondrial membrane potential and glutathione content were higher in the 10 mM pyruvate, 67 mM glucose media. • LACTATE and NAD+ content were higher in the spermatozoa incubated in the 10 mM pyruvate in a 67 mM Glucose-Tyrode's media. • The mechanism explaining the improvements may involve conversion of pyruvate to lactate and regeneration of NAD+. • The stallion spermatozoa may produce significant amounts of lactate under high Oxygen (Warburg effect). [ABSTRACT FROM AUTHOR]

The division of glycolysis into two separate pathways, aerobic and anaerobic, depending on the presence or absence of oxygen, respectively, was formulated over eight decades ago. The former ends with pyruvate, while the latter ends with lactate. Today, this division is confusing and misleading as research over the past 35 years clearly has demonstrated that glycolysis ends with lactate not only in cancerous cells but also in healthy tissues and cells. The present essay offers a review of the history of said division and the more recent knowledge that has been gained about glycolysis and its end-product, lactate. Then, it presents arguments in an attempt to explain why separating glycolysis into aerobic and anaerobic pathways persists among scientists, clinicians and teachers alike, despite convincing evidence that such division is not only wrong scientifically but also hinders progress in the field of energy metabolism. [ABSTRACT FROM AUTHOR]

d‐Serine plays vital physiological roles in the functional regulation of the mammalian brain, where it is produced from l‐serine by serine racemase and degraded by d‐amino acid oxidase. In the present study, we identified a new d‐serine metabolizing activity of serine hydroxymethyltransferase (SHMT) in bacteria as well as mammals. SHMT is known to catalyze the conversion of l‐serine and tetrahydrofolate (THF) to glycine and 5,10‐methylenetetrahydrofolate, respectively. In addition, we found that human and Escherichia coli SHMTs have d‐serine dehydratase activity, which degrades d‐serine to pyruvate and ammonia. We characterized this enzymatic activity along with canonical SHMT activity. Intriguingly, SHMT required THF to catalyze d‐serine dehydration and did not exhibit dehydratase activity toward l‐serine. Furthermore, SHMT did not use d‐serine as a substrate in the canonical hydroxymethyltransferase reaction. The d‐serine dehydratase activities of two isozymes of human SHMT were inhibited in the presence of a high concentration of THF, whereas that of E. coli SHMT was increased. The pH and temperature profiles of d‐serine dehydratase and serine hydroxymethyltransferase activities of these three SHMTs were partially distinct. The catalytic efficiency (kcat/Km) of dehydratase activity was lower than that of hydroxymethyltransferase activity. Nevertheless, the d‐serine dehydratase activity of SHMT was physiologically important because d‐serine inhibited the growth of an SHMT deletion mutant of E. coli, ∆glyA, more than that of the wild‐type strain. Collectively, these results suggest that SHMT is involved not only in l‐ but also in d‐serine metabolism through the degradation of d‐serine. [ABSTRACT FROM AUTHOR]

In the present study, cryo‐electron tomography was used to investigate the localization of 2‐oxoacid dehydrogenase complexes (OADCs) in cardiac mitochondria and mitochondrial inner membrane samples. Two classes of ordered OADC inner cores with different symmetries were distinguished and their quaternary structures modeled. One class corresponds to pyruvate dehydrogenase complexes and the other to dehydrogenase complexes of α‐ketoglutarate and branched‐chain α‐ketoacids. OADCs were shown to be localized in close proximity to membrane‐embedded respirasomes, as observed both in densely packed lamellar cristae of cardiac mitochondria and in ruptured mitochondrial samples where the dense packing is absent. This suggests the specificity of the OADC–respirasome interaction, which allows localized NADH/NAD+ exchange between OADCs and complex I of the respiratory chain. The importance of this local coupling is based on OADCs being the link between respiration, glycolysis and amino acid metabolism. The coupling of these basic metabolic processes can vary in different tissues and conditions and may be involved in the development of various pathologies. The present study shows that this important and previously missing parameter of mitochondrial complex coupling can be successfully assessed using cryo‐electron tomography. [ABSTRACT FROM AUTHOR]

Embryo quality evaluation during in vitro development is a crucial factor for the success of assisted reproductive technologies (ARTs). However, the subjectivity inherent in the morphological evaluation by embryologists can introduce inconsistencies that impact the optimal embryo choice for transfer. To provide a more comprehensive evaluation of embryo quality, we undertook the integration of embryo metabolomics alongside standardized morphokinetic classification. The culture medium of 55 embryos (derived from 21 couples undergoing ICSI) was collected at two timepoints (days 3 and 5). Samples were split into Good (n = 29), Lagging (n = 19), and Bad (n = 10) according to embryo morphokinetic evaluation. Embryo metabolic performance was assessed by monitoring the variation in specific metabolites (pyruvate, lactate, alanine, glutamine, acetate, formate) using 1H-NMR. Adjusted metabolite differentials were observed during the first 3 days of culture and found to be discriminative of embryo quality at the end of day 5. Pyruvate, alanine, glutamine, and acetate were major contributors to this discrimination. Good and Lagging embryos were found to export and accumulate pyruvate and glutamine in the first 3 days of culture, while Bad embryos consumed them. This suggests that Bad embryos have less active metabolic activity than Good and Lagging embryos, and these two metabolites are putative biomarkers for embryo quality. This study provides a more comprehensive evaluation of embryo quality and can lead to improvements in ARTs by enabling the selection of the best embryos. By combining morphological assessment and metabolomics, the selection of high-quality embryos with the potential to result in successful pregnancies may become more accurate and consistent. [ABSTRACT FROM AUTHOR]

3-hydroxypropionic acid (3-HP) is a valuable platform chemical with high demand in the global market. Owing to its sustainability and environmental affability, the biosynthesis of 3-HP has gained a great deal of attention. The major challenges in biological production of 3-HP is by-product accumulation which significantly affects the titre and yield of 3-HP. In this work, efforts have been made to investigate the metabolic engineering of Escherichia coli to circumvent these constraints. From the mRNA expression studies, it was found that yqhD, poxB, and pta-ackA were the primary targets. The deletion of genes showed significant changes in the synthesis of 3-HP and other major metabolites such as propanediol and acetate. The deletion of yqhD significantly decreased the synthesis of propanediol and diverted the carbon flux towards 3-HP. Furthermore, the combined deletion of poxB and pta-ackA significantly showed the reduction of acetate concentration. The enhancement of 3-HP production has been attained by the combinatorial deletion of yqhD, poxB, and pta-ackA resulted the titre (440 mM vs. 556 mM) and yield (0.31 vs. 0.40). The present work could be an effective tool for the enhanced production of 3-HP with the reduced level of by-product accumulation. [ABSTRACT FROM AUTHOR]

Enhancing magnetic resonance signal via hyperpolarization techniques enables the real‐time detection of metabolic transformations even in vivo. The use of para‐hydrogen to enhance 13C‐enriched metabolites has opened a rapid pathway for the production of hyperpolarized metabolites, which usually requires specialized equipment. Metabolite precursors that can be hyperpolarized and converted into metabolites at any given field would open up opportunities for many labs to make use of this technology because already existing hardware could be used. We report here on the complete synthesis and hyperpolarization of suitable precursor molecules of the side‐arm hydrogenation approach. The better accessibility to such side‐arms promises that the para‐hydrogen approach can be implemented in every lab with existing two channel NMR spectrometers for 1H and 13C independent of the magnetic field. [ABSTRACT FROM AUTHOR]

Introduction: Even in present-day times, cancer is one of the most fatal diseases. People are overwhelmed by pricey chemotherapy, immunotherapy, and other costly cancer therapies in poor and middle-income countries. Cancer cells grow under anaerobic and hypoxic conditions. Pyruvate is the final product of the anaerobic glycolysis pathway, and many cancer cells utilize pyruvate for their growth and development. The anaerobic microbiome produces many anti-cancer substances that can act as anti-tumor agents and are both feasible and of low cost. There are different mechanisms of action of the anaerobic microbiome, such as the production of short-chain fatty acids (SCFAs), and competition for the anaerobic environment includes the metabolic product pyruvate to form lactic acid for energy. Key findings: In this review, we have summarized the role of the metabolic approach of the anaerobic human microbiome in cancer prevention and treatment by interfering with cancer metabolite pyruvate. SCFAs possess decisive outcomes in condoning almost all the hallmarks of cancer and helping the spread of cancer to other body parts. Studies have demonstrated the impact and significance of using SCFA, which results from anaerobic bacteria, as an anti-cancer agent. Anaerobic bacteria-based cancer therapy has become a promising approach to treat cancer using obligate and facultative anaerobic bacteria because of their ability to penetrate and increase in an acidic hypoxic environment. Significance: This review attempts to provide the interconnection of cancer metabolism and anaerobic microbiome metabolism with a focus on pyruvate metabolism to understand and design unique anaerobic microbiota-based therapy for cancer patients. [ABSTRACT FROM AUTHOR]

To observe the therapeutic effect of intragastric administration of sodium pyruvate solution on deep Ⅱ° scald in diabetic rats and to analyze the possible mechanism. Methods Fifty male SD rats were randomly divided into the control group, model group and experimental groups 1, 2 and 3, with 10 rats in each group. The diabetic rat models were established by intraperitoneal injection of streptozotocin. After successful modeling, a deep partial thickness scald with diameter of 4 cm was inflicted on the back of each rat in the model group and the experimental groups. Rats in the experimental groups 1, 2 and 3 were given 2. 5%, 7. 5% and 10% sodium pyruvate solution by gavage, respectively, once a day, and rats in the control group and the model group were given the same amount of normal saline by gavage. On day 1, 3, 7, 14, and 21 of drug administration, the wound healing rate was observed and calculated, and the body weight and blood glucose of rats were detected. Nicotinamide adenine dinucleotide (NAD+/NADH), malondialdehyde (MDA), superoxide dismutase (SOD), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the wound tissues were detected by ELISA. Results The wound healing rates of the model group on day 14 and 21 of administration were lower than those of the control group, and the wound healing rate of each experimental group on day 14 and 21 of administration was higher than that of control group, and the wound healing rate of the experimental group 3 was higher than those of the experimental groups 1 and 2 (all P<0. 05). The blood glucose of the model group was higher than that of the control group at each time point of administration, and the blood glucose of each experimental group was lower than that of the model group, and that of experimental group 3 was lower than those of experimental groups 1 and 2 (all P<0. 05). The body weight of the model group was lower than that of the control group from day 3 to 21 of administration, and the body weight of each experimental group was higher than that of the model group, and the body weight of the experimental group 3 was higher than that of the experimental groups 1 and 2 from day 7 to 21 of administration (all P<0. 05). The levels of NAD+/ NADH and SOD in the wound tissues after administration in the model group were lower than those in the control group, and those in each experimental group were higher than those in the model group, and those in experimental group 3 were higher than those in experimental groups 1 and 2 (all P<0. 05). The levels of MDA, IL-6, and TNF-α in wound tissue after administration in the model group were higher than those in the control group, and those in each experimental group were lower than those in the model group, and those in experimental group 3 were lower than those in experimental groups 1 and 2 (all P<0. 05). Conclusion Intragastric administration of sodium pyruvate solution can promote wound healing, reduce blood glucose, and maintain normal body weight in diabetic rats with deep II° scald, and the mechanism may be related to inhibiting inflammatory response and peroxidation damage of wound and improving energy metabolism. [ABSTRACT FROM AUTHOR]

Parahydrogen‐induced polarization (PHIP) followed by polarization transfer to 13C is a rapidly developing technique for the generation of 13C‐hyperpolarized substrates. Chirality plays an essential role in living systems and differential metabolism of enantiomeric pairs of metabolic substrates is well documented. Inspired by asymmetric hydrogenation, here we report stereoPHIP, which involves the addition of parahydrogen to a prochiral substrate with a chiral catalyst followed by polarization transfer to 13C spins. We demonstrate that parahydrogen could be rapidly added to the prochiral precursor to both enantiomers of lactic acid (D and L), with both the (R,R) and (S,S) enantiomers of a chiral rhodium(I) catalyst to afford highly 13C‐hyperpolarized (over 20 %) L‐ and D‐lactate ester derivatives, respectively, with excellent stereoselectivity. We also show that the hyperpolarized 1H signal decays obtained with the (R,R) and (S,S) catalysts were markedly different. StereoPHIP expands the scope of conventional PHIP to the production of 13C hyperpolarized chiral substrates with high stereoselectivity. [ABSTRACT FROM AUTHOR]

Parahydrogen‐induced polarization (PHIP) followed by polarization transfer to 13C is a rapidly developing technique for the generation of 13C‐hyperpolarized substrates. Chirality plays an essential role in living systems and differential metabolism of enantiomeric pairs of metabolic substrates is well documented. Inspired by asymmetric hydrogenation, here we report stereoPHIP, which involves the addition of parahydrogen to a prochiral substrate with a chiral catalyst followed by polarization transfer to 13C spins. We demonstrate that parahydrogen could be rapidly added to the prochiral precursor to both enantiomers of lactic acid (D and L), with both the (R,R) and (S,S) enantiomers of a chiral rhodium(I) catalyst to afford highly 13C‐hyperpolarized (over 20 %) L‐ and D‐lactate ester derivatives, respectively, with excellent stereoselectivity. We also show that the hyperpolarized 1H signal decays obtained with the (R,R) and (S,S) catalysts were markedly different. StereoPHIP expands the scope of conventional PHIP to the production of 13C hyperpolarized chiral substrates with high stereoselectivity. [ABSTRACT FROM AUTHOR]

Hyperpolarization techniques increase nuclear spin polarization by more than four orders of magnitude, enabling metabolic MRI. Even though hyperpolarization has shown clear value in clinical studies, the complexity, cost and slowness of current equipment limits its widespread use. Here, a polarization procedure of [1‐13C]pyruvate based on parahydrogen‐induced polarization by side‐arm hydrogenation (PHIP‐SAH) in an automated polarizer is demonstrated. It is benchmarked in a study with 48 animals against a commercial dissolution dynamic nuclear polarization (d‐DNP) device. Purified, concentrated (≈70–160 mM) and highly hyperpolarized (≈18%) solutions of pyruvate are obtained at physiological pH for volumes up to 2 mL within 85 s in an automated process. The safety profile, image quality, as well as the quantitative perfusion and lactate‐to‐pyruvate ratios, are equivalent for PHIP and d‐DNP, rendering PHIP a viable alternative to established hyperpolarization techniques. [ABSTRACT FROM AUTHOR]

Background: With concerns about depletion of fossil fuel and environmental pollution, synthesis of biofuels such as isobutanol from low-cost substrate by microbial cell factories has attracted more and more attention. As one of the most promising carbon sources instead of food resources, acetate can be utilized by versatile microbes and converted into numerous valuable chemicals. Results: An isobutanol synthetic pathway using acetate as sole carbon source was constructed in E. coli. Pyruvate was designed to be generated via acetyl-CoA by pyruvate-ferredoxin oxidoreductase YdbK or anaplerotic pathway. Overexpression of transhydrogenase and NAD kinase increased the isobutanol titer of recombinant E. coli from 121.21 mg/L to 131.5 mg/L under batch cultivation. Further optimization of acetate supplement concentration achieved 157.05 mg/L isobutanol accumulation in WY002, representing the highest isobutanol titer by using acetate as sole carbon source. Conclusions: The utilization of acetate as carbon source for microbial production of valuable chemicals such as isobutanol could reduce the consumption of food-based substrates and save production cost. Engineering strategies applied in this study will provide a useful reference for microbial production of pyruvate derived chemical compounds from acetate. [ABSTRACT FROM AUTHOR]

Metabolic magnetic resonance imaging (MRI) using hyperpolarized (HP) pyruvate is becoming a non‐invasive technique for diagnosing, staging, and monitoring response to treatment in cancer and other diseases. The clinically established method for producing HP pyruvate, dissolution dynamic nuclear polarization, however, is rather complex and slow. Signal Amplification By Reversible Exchange (SABRE) is an ultra‐fast and low‐cost method based on fast chemical exchange. Here, for the first time, we demonstrate not only in vivo utility, but also metabolic MRI with SABRE. We present a novel routine to produce aqueous HP [1‐13C]pyruvate‐d3 for injection in 6 minutes. The injected solution was sterile, non‐toxic, pH neutral and contained ≈30 mM [1‐13C]pyruvate‐d3 polarized to ≈11 % (residual 250 mM methanol and 20 μM catalyst). It was obtained by rapid solvent evaporation and metal filtering, which we detail in this manuscript. This achievement makes HP pyruvate MRI available to a wide biomedical community for fast metabolic imaging of living organisms. [ABSTRACT FROM AUTHOR]

The exposure to UVA (320–400 nm) irradiation is a major threat to human skin concerning photoaging and carcinogenesis. It has been shown that UVA irradiation can induce reactive oxygen species (ROS) and DNA mutations, such as 8-hydroxydeoxyguanosine. Furthermore, UVA induces the expression of photoaging-associated matrix metalloproteases (MMPs), especially of matrix metalloprotease 1 (MMP 1) and matrix metalloprotease 3 (MMP 3). In addition to this, it was recently shown that UVA-induced ROS also increase glucose metabolism of melanoma cells, however, the influence of UVA on the glucose metabolism of non-malignant cells of the human skin has, so far, not been investigated in detail. Here, we investigated the UVA-induced changes in glucose metabolism and the functional relevance of these changes in primary fibroblasts—normal non-malignant cells of the skin. These cells showed an UVA-induced enhanced glucose consumption and lactate production and changes in pyruvate production. As it has been proposed that pyruvate could have antioxidant properties we tested the functional relevance of pyruvate as protective agent against UVA-induced ROS. Our initial experiments support earlier publications, demonstrating that pyruvate treated with H2O2 is non-enzymatically transformed to acetate. Furthermore, we show that this decarboxylation of pyruvate to acetate also occurs upon UVA irradiation. In addition to this, we could show that in fibroblasts pyruvate has antioxidant properties as enhanced levels of pyruvate protect cells from UVA-induced ROS and partially from a DNA mutation by the modified base 8-hydroxydeoxyguanosine. Furthermore, we describe for the first time, that the interaction of UVA with pyruvate is relevant for the regulation of photoaging-associated MMP 1 and MMP 3 expression. [ABSTRACT FROM AUTHOR]

Recently, we reported a circular cell culture (CCC) system using microalgae and animal muscle cells for sustainable culture food production. However, lactate accumulation excreted by animal cells in the system characterized by medium reuse was a huge problem. To solve the problem, as an advanced CCC, we used a lactate-assimilating cyanobacterium Synechococcus sp. PCC 7002, using gene-recombination technology that synthesises pyruvate from lactate. We found that the cyanobacteria and animal cells mutually exchanged substances via their waste media: (i) cyanobacteria used lactate and ammonia excreted by animal muscle cells, and (ii) the animal cells used pyruvate and some amino acids excreted by the cyanobacteria. Because of this, animal muscle C2C12 cells were amplified efficiently without animal serum in cyanobacterial culture waste medium in two cycles (first cycle: 3.6-fold; second cycle: 3.9-fold/three days-cultivation) using the same reuse medium. We believe that this advanced CCC system will solve the problem of lactate accumulation in cell culture and lead to efficient cultured food production. [ABSTRACT FROM AUTHOR]

Lichenysin, a cyclic lipopeptide biosurfactant produced by Bacillus licheniformis, is composed of aspartate, glutamine, valine, leucine, isoleucine, and branched chain fatty acids. The synthesis of these amino acids and fatty acids requires pyruvate and NADPH as the primary precursor and cofactor. Therefore, a sufficient supply of pyruvate and NADPH is crucial for lichenysin production. This study aimed to increase lichenysin production by constructing a synthetic ED pathway in B. licheniformis WX02 through introducing phosphogluconate dehydratase (encoded by gene edd) and 2-keto-3-deoxygluconate 6-phosphate aldolase (encoded by gene eda) from Escherichia coli. Additionally, the NADP+-dependent glucose-6-phosphate dehydrogenase (encoded by gene zwf) was overexpressed, resulting in an engineered strain WX02/pHY-edda(Ec)-zwf. Analysis of the fermentation process revealed that the concentrations of pyruvate, aspartate, glutamine, valine, leucine, branched-chain fatty acids (iC15:0, aC15:0, iC16:0, iC17:0), and NADPH in WX02/pHY-edda(Ec)-zwf were increased by 77.21%, 80.41%, 85.31%, 141.64%, 44.94%, 35.08%, 38.08%, 19.33%, 21.16%, and 425%, respectively, compared to the control strain WX02/pHY300, which resulted in a 45.43% increase of lichenysin titer. This work took advantage of the ED pathway to increase lichenysin production for the first time, and provides a promising strategy for boosting the productivity of biochemicals that require pyruvate and NADPH as precursor and cofactor. [ABSTRACT FROM AUTHOR]

Epimedium sagittatum (Sieb. et Zucc.) Maxim., a traditional medicinal plant in Asia, is widely used in clinical settings but its safety in vivo is unclear. This study investigated the sub-chronic toxicity of E. sagittatum aqueous extract to rats with a 13-week daily intragastric administration of 7.5, 15, or 30 g/kg. Nine constituents of the aqueous extract were identified by ultra-performance liquid chromatography (UPLC). Organ weights, organ coefficients, serum biochemistry parameters, histopathology, and metabolomic analysis were performed. In female rats, treatment increased the liver, thymus, and adrenal gland coefficients (p < 0.05). Liver, pancreas, and adrenal gland injury were observed. The levels of six metabolites were altered by the treatment (p < 0.05). In male rats, treatment altered liver, heart, and thymus coefficients (p < 0.05) and liver, adrenal gland, and heart injury were observed. The levels of 11 metabolites were altered (p < 0.05). The no-observed-adverse-effect level was not determined but would be below 7.5 g/kg in rats treated for 13 weeks. In female rats, E. sagittatum may injure the liver and pancreas and dysregulate the biosynthesis of phenylalanine, tyrosine, tryptophan, valine, leucine, and isoleucine and the metabolism of phenylalanine. In male rats, the extract may injure the liver and adrenal gland and dysregulate the biosynthesis of valine, leucine, and isoleucine and the metabolism of pyruvate. [ABSTRACT FROM AUTHOR]

Cancer cells strongly upregulate glucose uptake and glycolysis to produce vital biomolecules for cancer cell survival, proliferation, and metastasis as ATP, lipids, proteins, nucleotides, and lactate. The Warburg effect is tumours' unique glucose oxidation to give lactate (not pyruvate) even in the presence of oxygen. Nicotinamide adenine dinucleotide (NAD/NADH.H) is used in glycolysis via glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase (LDH). Both catalyse reversible biochemical reactions to produce 1,3-diphosphoglycerate and lactate, respectively. In this expert opinion and based on published evidence, the author suggests that: "In transformed cells and hyperglycolytic cancer cells, the Warburg effect (permanent conversion of pyruvate to lactate) occurs secondary to a vicious cycle and a closed circuit between GAPDH and LDH (reaction of carcinogenesis) causing increased endogenous oxidative stress and subsequent carcinogenesis. Mitochondrial defects in cancer cells cause hyperglycolysis resulting in NADH.H accumulation (produced during GAPDH step) that obligatorily drives LDH to become an irreversible reaction in the direction of lactate formation (Warburg effect) but not pyruvate formation. Likewise, LDH oxidizes NADH.H producing excessive NAD+ that secondarily drives GAPDH reaction to be irreversible to produce NADH.H and so on. Pyruvate is an antioxidant while lactate is pro-oxidant, causing increased endogenous oxidative stress in cancer cells, tumour's hypoxia and obligatory hyperglycolysis with NADH.H overproduction (GAPDH step) to be consumed in the LDH step for lactate production and NAD+ generation (utilized by GAPDH) and so on". This confirms Warburg's origin of cancer cells. Best anticancer applications based on this hypothesis are: breaking this closed vicious circle using siRNA to target GAPDH and LDH, avoiding strong oxidants (as many cancer chemotherapeutics), and using strong antioxidants for causing antioxidant–oxidant antagonism or antioxidant–lactate antagonism to inhibit the Warburg effect. Strong natural antioxidants of prophetic medicine (related to Prophet Muhammad peace be upon him) such as Zamzam water, Nigella sativa, costus, Ajwa date fruit, olive oil, Al-hijamah and natural honey are strongly recommended to prevent and antagonize the Warburg effect. [ABSTRACT FROM AUTHOR]

Pyruvate sits at an important metabolic crossroads of intermediary metabolism. As a product of glycolysis in the cytosol, it must be transported into the mitochondrial matrix for the energy stored in this nutrient to be fully harnessed to generate ATP or to become the building block of new biomolecules. Given the requirement for mitochondrial import, it is not surprising that the mitochondrial pyruvate carrier (MPC) has emerged as a target for therapeutic intervention in a variety of diseases characterized by altered mitochondrial and intermediary metabolism. In this review, we focus on the role of the MPC and related metabolic pathways in the liver in regulating hepatic and systemic energy metabolism and summarize the current state of targeting this pathway to treat diseases of the liver. Available evidence suggests that inhibiting the MPC in hepatocytes and other cells of the liver produces a variety of beneficial effects for treating type 2 diabetes and nonalcoholic steatohepatitis. We also highlight areas where our understanding is incomplete regarding the pleiotropic effects of MPC inhibition. [ABSTRACT FROM AUTHOR]

Pyruvate is a hub of various endogenous metabolic pathways, including glycolysis, TCA cycle, amino acid, and fatty acid biosynthesis. It has also been used as a precursor for pyruvate-derived compounds such as acetoin, 2,3-butanediol (2,3-BD), butanol, butyrate, and L-alanine biosynthesis. Pyruvate and derivatives are widely utilized in food, pharmaceuticals, pesticides, feed additives, and bioenergy industries. However, compounds such as pyruvate, acetoin, and butanol are often chemically synthesized from fossil feedstocks, resulting in declining fossil fuels and increasing environmental pollution. Metabolic engineering is a powerful tool for producing eco-friendly chemicals from renewable biomass resources through microbial fermentation. Here, we review and systematically summarize recent advances in the biosynthesis pathways, regulatory mechanisms, and metabolic engineering strategies for pyruvate and derivatives. Furthermore, the establishment of sustainable industrial synthesis platforms based on alternative substrates and new tools to produce these compounds is elaborated. Finally, we discuss the potential difficulties in the current metabolic engineering of pyruvate and derivatives and promising strategies for constructing efficient producers. [ABSTRACT FROM AUTHOR]

Obesity is associated with complex adipose tissue energy metabolism remodeling. Whether AT metabolic reprogramming differs according to body mass index (BMI) and across different obesity classes is unknown. This study's purpose was to evaluate and compare bioenergetics and energy substrate preference of visceral adipose tissue (VAT) pertaining to individuals with obesity class 2 and class 3. VAT obtained from patients with obesity (n = 15) class 2 (n = 7; BMI 37.53 ± 0.58 kg/m2) or class 3 (n = 8; BMI 47.79 ± 1.52 kg/m2) was used to assess oxygen consumption rate (OCR) bioenergetics and mitochondrial substrate preferences. VAT of patients with obesity class 3 presented significantly higher non-mitochondrial oxygen consumption (p < 0.05). In VAT of patients with obesity class 2, inhibition of pyruvate and glutamine metabolism significantly decreased maximal respiration and spare respiratory capacity (p < 0.05), while pyruvate and fatty acid metabolism inhibition, which renders glutamine the only available substrate, increased the proton leak with a protective role against oxidative stress (p < 0.05). In conclusion, VAT bioenergetics of patients with obesity class 2 depicts a greater dependence on glucose/pyruvate and glutamine metabolism, suggesting that patients within this BMI range are more likely to be responsive to interventions based on energetic substrate modulation for obesity treatment. [ABSTRACT FROM AUTHOR]

Pseudomonas putida KT2440 is an attractive bacterial host for biotechnological production of valuable chemicals from renewable lignocellulosic feedstocks as it can valorize lignin-derived aromatics or glucose obtainable from cellulose. P. putida EM42, a genome-reduced variant of strain KT2440 endowed with advantageous physiological properties, was recently engineered for growth on cellobiose, a major cellooligosaccharide product of enzymatic cellulose hydrolysis. Co-utilization of cellobiose and glucose was achieved in a mutant lacking periplasmic glucose dehydrogenase Gcd (PP_1444). However, the cause of the co-utilization phenotype remained to be understood and the Δ gcd strain had a significant growth defect. In this study, we investigated the basis of the simultaneous uptake of the two sugars and accelerated the growth of P. putida EM42 Δ gcd mutant for the bioproduction of valuable compounds from glucose and cellobiose. We show that the gcd deletion lifted the inhibition of the exogenous β-glucosidase BglC from Thermobifida fusca exerted by the intermediates of the periplasmic glucose oxidation pathway. The additional deletion of hexR gene, which encodes a repressor of the upper glycolysis genes, failed to restore rapid growth on glucose. The reduced growth rate of the Δ gcd mutant was partially compensated by the implantation of heterologous glucose and cellobiose transporters (Glf from Zymomonas mobilis and LacY from Escherichia coli , respectively). Remarkably, this intervention resulted in the accumulation of pyruvate in aerobic P. putida cultures. We demonstrated that the excess of this key metabolic intermediate can be redirected to the enhanced biosynthesis of ethanol and lactate. The pyruvate overproduction phenotype was then unveiled by an upgraded genome-scale metabolic model constrained with proteomic and kinetic data. The model pointed to the saturation of glucose catabolism enzymes due to unregulated substrate uptake and it predicted improved bioproduction of pyruvate-derived chemicals by the engineered strain. This work sheds light on the co-metabolism of cellulosic sugars in an attractive biotechnological host and introduces a novel strategy for pyruvate overproduction in bacterial cultures under aerobic conditions. • Co-utilization of glucose and cellobiose by a Δ gcd mutant of P. putida EM42. • Growth defect of the mutant compensated by implanting exogenous sugar transporters. • Enhanced carbon influx caused aerobic overproduction of pyruvate and acetate. • Carbon from excess pyruvate streamed into ethanol or L-lactate. • Pyruvate overproduction unveiled by a mathematical model of P. putida metabolism. [ABSTRACT FROM AUTHOR]

This article proposes an evolutionary trajectory for the development of biological energy producing systems. Six main stages of energy producing system evolution are described, from early evolutionary pyrite-pulled mechanism through the Last Universal Common Ancestor (LUCA) to contemporary systems. We define the Last Pure Chemical Entity (LPCE) as the last completely non-enzymatic entity. LPCE could have had some life-like properties, but lacked genetic information carriers, thus showed greater instability and environmental dependence than LUCA. A double bubble model is proposed for compartmentalization and cellularization as a prerequisite to both highly efficient protein synthesis and transmembrane ion-gradient. The article finds that although LUCA predominantly functioned anaerobically, it was a non-exclusive anaerobe, and sulfur dominated metabolism preceded phosphate dominated one. • Fe-S motifs are essential through the evolution of bioenergetics. • Imidazole is important factor in deprotonation at the origin of metabolic pathways. • Last Pure Chemical Entity fully operating without enzymes had to exist. • Last Universal Common Ancestor must have been a facultative aerobe. • In the course of evolution of bioenergetics the efficacy increased. [ABSTRACT FROM AUTHOR]

Parahydrogen‐induced polarization is a hyperpolarization method that exploits the spin order of hydrogen enriched in the para‐isomer, by means of a chemical reaction. Recently, its field of application has been extended significantly, through the introduction of non‐hydrogenative PHIP (i. e. SABRE) and of innovative h‐PHIP strategies that allowed to increase the intensity of the MR signals in molecules relevant for biological applications. This Concept article aims to show the potentialities of this hyperpolarization method in the field of diagnostics, through the discussion of some of the reported applications of parahydrogen polarized substrates. A section is also dedicated to the methods that have been introduced for the purification of parahydrogen polarized products, in order to make them suitable for biological studies. [ABSTRACT FROM AUTHOR]

Cachexia is a systemic disease associated with several pathologies, including cancer, that leads to excessive weight loss due to enhanced protein degradation. Previously, we showed that cachectic features in myotubes are provoked by a metabolic shift toward lactic fermentation. Our previous results led us to hyphotesise that increasing pyruvate concentration could impede the metabolic modifications responsible for induction of cachexia in myotubes. Here, we demonstrated that the addition of sodium pyruvate in conditioned media from CT26 colon cancer cells (CM CT26) prevents the onset of either phenotypic and metabolic cachectic features. Myotubes treated with CM CT26 containing sodium pyruvate show a phenotype similar to the healthy counterpart and display lactate production, oxygen consumption, and pyruvate dehydrogenase activity as control myotubes. The use of the Mitochondrial Pyruvate Carrier inhibitor UK5099, highlights the importance of mitochondrial pyruvate amount in the prevention of cachexia. Indeed, UK5099‐treated myotubes show cachectic features as those observed in myotubes treated with CM CT26. Finally, we found that sodium pyruvate is able to decrease STAT3 phosphorylation level, a signaling pathway involved in the induction of cachexia in myotubes. Collectively, our results show that cachexia in myotubes could be prevented by the utilization of sodium pyruvate which impedes the metabolic modifications responsible for the acquisition of the cachectic features. [ABSTRACT FROM AUTHOR]

In dairy cows, metabolic disorders are mainly found in the last weeks of the dry period and the first weeks after calving (transit period). Therefore, the purpose of this study was to investigate the hormonal regulation of the concentration of glucose and its derivatives in the blood of dairy cows during the transit period. The study was conducted on cows of 2-4 lactations, with a capacity of 7.8-8.2 thousand kg of milk for previous lactation. Blood for research was taken from cows 7-10 days before calving and Days 2-4, Days 10-14, and Days 30-40 after calving. The concentration of glucose in blood plasma was determined by the glucose oxidase method, pyruvate - by the modified Umbright method, lactate -- by reaction with paraoxydyphenyl, and hormone content -- by enzyme-linked immunosorbent assay. It was established that high-performance dairy cows during the transit period experience substantial changes in carbohydrate metabolism and the functional state of organs and systems, which are aimed at ensuring high productivity. Thus, hypoglycaemia is found in cows within two weeks after calving. At the same time, with a decrease in the concentration of glucose in the blood plasma of cows, the content of pyruvate and lactate increases, as well as the lactate/pyruvate ratio, which indicates an increase in gluconeogenesis. Negative energy balance and increased gluconeogenesis lead to a decrease in the synthesis of insulin and insulin-like growth factor. Compared to the final dry period, on Days 2-4 of lactation, the concentration of leptin in the blood plasma of cows decreased threefold and stayed at a low level until Day 40 of lactation. Plasma cortisol levels were highest on Days 2-4 and 10-14 of lactation. Intensive cortisol synthesis during the period of energy deficiency increases gluconeogenesis, which is possible due to lipolysis and proteolysis. In the first days after calving, the content of thyroxine and triiodothyronine in the blood plasma of cows decreased. Inhibition of thyroid hormone production is a consequence of the physiological regulatory features of this period. Thus, in highly productive cows during the transit period, attention should be paid to maintaining vital body functions and their well-coordinated endocrine regulation, which will ensure a physiologically balanced metabolic rate, successful calving, high milk productivity, and animal health [ABSTRACT FROM AUTHOR]

Pyruvate is an important energy substance during early embryonic development of mammals. However, the underlying mechanisms of pyruvate during early embryonic development in pigs and its role in zygotic genome activation (ZGA) are not fully understood. Here, based on a previous RNA-seq dataset of porcine early embryos, we found that pyruvate metabolism-related genes started to be expressed at the 4-cell stage and that pyruvate metabolism-related genes were correlated with porcine ZGA marker genes. To determine the function of pyruvate in porcine embryos, in vitro fertilization (IVF) embryos were cultured in PZM-3 medium (control group); modified PZM-3 medium that only contains pyruvate and lactate plus salts (+P group); or modified PZM-3 medium lacking pyruvate (-P group). The 4-cell arrest rate at 72 h was significantly increased in the -P group compared to the +P group (P < 0.05). In addition, we observed that the reactive oxygen species (ROS) level was significantly increased and that the adenosine triphosphate (ATP) level was significantly (P < 0.05) decreased in the -P group compared to the +P group. Moreover, the expression of ZGA marker genes and SIRT1 protein in embryos was significantly decreased in the -P group compared to the +P group (P < 0.05). Furthermore, the acetylation level of H3K9 was significantly decreased (P < 0.05) and the methylation level of H3K9 was significantly increased (P < 0.05) in the -P group compared to the +P group. In summary, our findings demonstrate that pyruvate affects early embryonic development in pigs by promoting ZGA and reducing oxidative stress levels. • Genes related to pyruvate metabolism were correlated with porcine zygotic genome activation marker genes. • Pyruvate can reduce 4-cell arrest and oxidative stress levels in porcine embryos. • Pyruvate can promote ZGA by affecting H3K9 modification levels in porcine embryos. [ABSTRACT FROM AUTHOR]

Enantioselective catalytic formation of polyfunctional molecules, such as non‐natural amino acids, is important for the efficient production of many chiral compounds. To this end, we present here the synthesis and evaluation of the catalytic activity of bifunctional peptide–thiourea organocatalysts. These hybrid organocatalysts consist of Pro‐Pro dipeptide and thiourea moiety connected via a 1,2‐diaminocyclohexane unit. These catalysts promoted challenging Mannich reaction between α‐imino esters and pyruvates, providing orthogonally protected oxo‐glutamate derivatives. The N‐tosyl‐protected imino ester, as the most active imine, was required to compensate for the poor reactivity of pyruvates. DFT calculations, NMR, and CD spectroscopy help elucidate the mode of action of these catalysts. Configuration of the dipeptide Pro‐Pro moiety is responsible for the sense of the stereoinduction of the Mannich reaction. [ABSTRACT FROM AUTHOR]

Hyperpolarization methods in magnetic resonance enhance the signals by several orders of magnitude, opening new windows for real‐time investigations of dynamic processes in vitro and in vivo. Here, we propose a field‐independent para‐hydrogen‐based pulsed method to produce rapidly hyperpolarized 13C‐labeled substrates. We demonstrate the method by polarizing the carboxylic carbon of the pyruvate moiety in a purposely designed precursor to 24 % at ≈22 mT. Following a fast purification procedure, we measure 8 % polarization on free [1‐13C]pyruvate in clean water solutions at physiological conditions at 7 T. The enhanced signals allow real‐time monitoring of the pyruvate‐lactate conversion in cancer cells, demonstrating the potential of the method for biomedical applications in combination with existing or developing magnetic resonance technologies. [ABSTRACT FROM AUTHOR]

Hyperpolarization methods in magnetic resonance enhance the signals by several orders of magnitude, opening new windows for real‐time investigations of dynamic processes in vitro and in vivo. Here, we propose a field‐independent para‐hydrogen‐based pulsed method to produce rapidly hyperpolarized 13C‐labeled substrates. We demonstrate the method by polarizing the carboxylic carbon of the pyruvate moiety in a purposely designed precursor to 24 % at ≈22 mT. Following a fast purification procedure, we measure 8 % polarization on free [1‐13C]pyruvate in clean water solutions at physiological conditions at 7 T. The enhanced signals allow real‐time monitoring of the pyruvate‐lactate conversion in cancer cells, demonstrating the potential of the method for biomedical applications in combination with existing or developing magnetic resonance technologies. [ABSTRACT FROM AUTHOR]

Myoglobin (Mb), besides its roles as an oxygen (O2) carrier/storage protein and nitric oxide NO scavenger/producer, may participate in lipid trafficking and metabolite binding. Our recent findings have shown that O2 is released from oxy-Mb upon interaction with lactate (LAC, anerobic glycolysis end-product). Since pyruvate (PYR) is structurally similar and metabolically related to LAC, we investigated the effects of PYR (aerobic glycolysis end-product) on Mb using isothermal titration calorimetry, circular dichroism, and O2-kinetic studies to evaluate PYR affinity toward Mb and to compare the effects of PYR and LAC on O2 release kinetics of oxy-Mb. Similar to LAC, PYR interacts with both oxy- and deoxy-Mb with a 1:1 stoichiometry. Time-resolved circular dichroism spectra revealed that there are no major conformational changes in the secondary structures of oxy- or deoxy-Mb during interactions with PYR or LAC. However, we found contrasting results with respect to binding affinities and substrate preference, where PYR has higher affinity toward deoxy-Mb when compared with LAC (which prefers oxy-Mb). Furthermore, PYR interaction with oxy-Mb releases a significantly lower amount of O2 than LAC. Taken together, our findings support the hypothesis that glycolytic end-products play a distinctive role in the Mb-rich tissues by serving as novel regulators of O2 availability, and/or by impacting other activities related to oxy-/deoxy-Mb toggling in resting vs. exercised or metabolically activated conditions. [ABSTRACT FROM AUTHOR]

ParaHydrogen Induced Polarization-Side Arm Hydrogenation (PHIP-SAH) is an inexpensive tool to obtain hyperpolarized pyruvate (and other metabolites) that can be applied to in vivo diagnostics, for the investigation of metabolic processes. This method is based on hydrogenation, using hydrogen enriched in the para-isomer, of unsaturated substrates, catalyzed, usually, by a homogeneous rhodium(I) complex. In this work, the effect of the solvent on the hydrogenation efficiency and the hyperpolarization level were investigated. Coordinating solvents, such as acetone and methanol, can increase significantly either the efficiency or the hyperpolarization level, but they are not compatible with the intended metabolic applications. The phase extraction of the hyperpolarized product (sodium pyruvate) in an aqueous solution was obtained carrying out the hydrogenation reaction in chloroform and toluene. The traces of the organic solvents in the water phase were removed, by means of filtration through a lipophilic resin, thus improving the biocompatibility of the aqueous solution of the hyperpolarized product. [Display omitted] • Hydrogenation in acetone or methanol can be quite efficient or give high polarization. • Chloroform and toluene were used to extract pyruvate in an aqueous solvent. • Traces of solvents are removed from the aqueous solution using a lipophilic resin. [ABSTRACT FROM AUTHOR]

Pyruvate dehydrogenase (PDH), a key enzyme on the mitochondrial outer membrane, has been found to decrease activity notably in early brain injury (EBI) after subarachnoid hemorrhage (SAH). It has been demonstrated that PDH is associated with the production of reactive oxygen species (ROS) and apoptosis. Hence, in this study, we aimed to determine the cause of the decreased PDH activity and explore the potential role of PDH in EBI. We investigated the expression changes of PDH and pyruvate dehydrogenase kinase (PDK) in vivo and in vitro. Then, we explored the possible effects of PDH and ROS after SAH. The results showed that early overexpression of PDK4 promoted the phosphorylation of PDH, inhibited PDH activity, and may play a protective role after SAH in vivo and in vitro. Finally, we investigated the levels of PDK4 and pyruvate, which accumulated due to decreased PDH activity, in the cerebrospinal fluid (CSF) of 34 patients with SAH. Statistical analysis revealed that PDK4 and pyruvate expression was elevated in the CSF of SAH patients compared with that of controls, and this high expression correlated with the degree of neurological impairment and long-term outcome. Taken together, the results show that PDK4 has the potential to serve as a new therapeutic target and biomarker for assisting in the diagnosis of SAH severity and prediction of recovery. [ABSTRACT FROM AUTHOR]

A novel electrochemical immunosensor for lactate dehydrogenase (LDH) detection was proposed based on analyte‐driven catalytic reaction by attaching LDH antibodies on multi‐walled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) modified glassy carbon electrodes (GCE). As LDH was captured by the antibodies on electrode surface, it catalyzed the formation of pyruvate and the reduced form of nicotinamide adenine dinucleotide (NADH), thus a sensitive electrochemical signal obtained from the above redox reaction was recorded by differential pulse voltammetry (DPV). Under optimum conditions, the developed immunosensor exhibits high sensitivity for LDH quantification ranging from 0.001 μg/mL to 0.5 μg/mL with a low detection limit at 0.39 ng/mL. This developed immunosensor reveals ideal accuracy and feasibility for LDH detection in Streptococcus uberis (S. uberis) induced bovine mammary epithelial cells (MECs) samples by comparison with conventional commercial kit, which shows remarkably application potential in diseases diagnosis. [ABSTRACT FROM AUTHOR]