Glucose Metabolites Research Articles

ASPROSIN: RELATION TO OXIDATIVE STRESS FOR METABOLIC SYNDROME PATIENTS IN MOSUL/IRAQ

Background: Asprosin is a protein hormone important in regulating appetite; glucose and lipid metabolites are secreted during fasting. Aims: The present study investigates the relationship between asprosin level and oxidative stress in MetS. Methods: The study included 171 participants persons aged 35–65 years who were divided into two groups: a control group, which included 75 participants, and a patient group, which included 95 participants from patients getting treatment at the Ibn Sina Educational Hospital in the Iraqi city of Mosul. Ethical approval was obtained from the Iraqi Ministry of Health - Nineveh Health. Five milliliters of venous blood were taken following a fast for an entire night. To perform oxidative and antioxidative factor tests as well as clinical evaluations. Results: Asprosin hormone levels in MetS significantly increased, but a significant decrease of antioxidative (glutathione, total antioxidant capacity, and arylesterase) also A substantial rise in malondialdehyde, lactoperoxidase, and peroxidase. It was found through the linear correlation coefficient (R) that there was a significant positive correlation between asprosin and oxidative and an inverse correlation with antioxidative variables. Discussion: These findings imply that asprosin is an indicator of metabolic disorders and is associated with MetS and oxidative stress indicators. Conclusions: Therefore, it can be considered a new indicator and a promising tool for diagnosis and treatment to initiate and develop.

Dimethyl Fumarate Reduces Methylglyoxal-derived Carbonyl Stress Through Nrf2/GSH Activation in SH-SY5Y Cells.

Carbonyl stress refers to the excessive accumulation of advanced glycation end products (AGEs) in mammalian tissues. This phenomenon plays a significant role in the pathogenesis of various diseases, including diabetes, chronic renal failure, arteriosclerosis, and central nervous system (CNS) disorders. We have previously demonstrated that an increase in glutathione concentration, dependent on the nuclear factor erythroid 2-related factor 2 (Nrf2) system, provides a potent cytoprotective effect against Methylglyoxal (MGO)-induced carbonyl stress. Meanwhile, dimethyl fumarate (DMF), known for its Nrf2-activating effects, was recently approved as a treatment for multiple sclerosis (MS), a neurodegenerative disease. DMF is a first line therapy for relapsing-remitting MS and may also be effective for other neurodegenerative conditions. However, the detailed mechanisms by which DMF mitigates neurodegenerative pathologies remain unclear. This study investigates the impact of DMF on anticarbonyl activity and its underlying mechanism focusing on the accumulation of carbonyl protein in the cell. MGO, a glucose metabolite, was used to induce carbonylation in the neuronal cell line. MGO is a typical carbonyl compound that readily reacts with arginine and lysine residues to form AGE-modified proteins. Methylglyoxal-derived hydroimidazolone 1 (MG-H1) often forms uncharged, hydrophobic residues on the protein surface, which can affect protein distribution and lead to misfolding. Our findings indicate that DMF increases levels of glutathione (GSH), glutamate cysteine ligase modifier subunit (GCLM), and nuclear Nrf2 in SH-SY5Y cells. Importantly, DMF pretreatment significantly reduced the accumulation of MG-H1-modified proteins. Furthermore, this effect of DMF was diminished when Nrf2 expression was suppressed and when GCL, a rate-limiting enzyme in GSH synthesis, was inhibited. Thus, the increase in GSH levels, leading to the activation of the Nrf2 pathway, a key factor in DMF's ability to suppress the accumulation of MG-H1-modified proteins. This study is the first to demonstrate that DMF possesses strong anticarbonyl stress activity in neuronal cells. Therefore, future research may extend the application of DMF to other CNS diseases associated with carbonyl stress, such as Alzheimer's and Parkinson's disease.

The effect of small increases in blood glucose on insulin secretion and endogenous glucose production in humans.

Small glycemic increments (≤0.5 mmol/L) can exert suppressive actions on endogenous glucose production (EGP) however it is unclear if this is an insulin dependent or independent process. Here, we performed a low-rate glucose infusion in control participants without diabetes and in people with type 1 diabetes (T1D) to better understand this phenomenon. Glucose kinetics, hormones and metabolites were measured during a 1 mg/kg/min glucose infusion (90 min) which rapidly increased glucose by ∼0.3 mmol/L in control participants. Insulin concentrations and secretion quickly increased by ∼20%, resulting in a ∼40% suppression of EGP, while glucose disposal remained unchanged. Free fatty acids (FFA) and glucagon were gradually suppressed to ∼30% below baseline at 60 min. When repeated under constant basal insulin concentrations in participants with T1D, glucose infusion caused only partial and transient EGP suppression, hence glucose increased in a near-linear manner, reaching levels ∼2 mmol/L above baseline at 90 min. FFAs and glucagon remained unchanged, while glucose disposal modestly increased. This demonstrates that small glycemic increments exert subtle stimulatory effects on insulin secretion that have potent metabolic actions on the liver and adipose tissue. It is conceivable that subtle increases in glucose could potentially serve as a signal for β-cell adaptation.

Variable glucagon metabolic actions in diverse mouse models of obesity and type 2 diabetes

ObjectiveThe study aimed to investigate the effects of glucagon on metabolic pathways in mouse models of obesity, fatty liver disease, and type 2 diabetes (T2D) to determine the extent and variability of hepatic glucagon resistance in these conditions. MethodsWe investigated glucagon's effects in mouse models of fatty liver disease, obesity, and type 2 diabetes (T2D), including male BKS-db/db, high-fat diet-fed, and western diet-fed C57Bl/6 mice. Glucagon tolerance tests were performed using the selective glucagon receptor agonist acyl-glucagon (IUB288). Blood glucose, serum and liver metabolites include lipids and amino acids were measured. Additionally, liver protein expression related to glucagon signalling and a comprehensive liver metabolomics were performed. ResultsWestern diet-fed mice displayed impaired glucagon response, with reduced blood glucose and PKA activation. In contrast, high-fat diet-fed and db/db mice maintained normal glucagon sensitivity, showing significant elevations in blood glucose and phospho-PKA motif protein expression. Acyl-glucagon treatment also lowered liver alanine and histidine levels in high-fat diet-fed mice, but not in western diet-fed mice. Additionally, some amino acids, such as methionine, were increased by acyl-glucagon only in chow diet control mice. Despite normal glucagon sensitivity in PKA signalling, db/db mice had a distinct metabolomic response, with acyl-glucagon significantly altering 90 metabolites in db/+ mice but only 42 in db/db mice, and classic glucagon-regulated metabolites, such as cyclic adenosine monophosphate (cAMP), being less responsive in db/db mice. ConclusionsThe study reveals that hepatic glucagon resistance in obesity and T2D is complex and not uniform across metabolic pathways, underscoring the complexity of glucagon action in these conditions.

Adaptations in hepatic glucose metabolism after chronic social defeat stress in mice

Chronic stress has been shown to induce hyperglycemia in both peripheral blood and the brain, yet the detailed mechanisms of glucose metabolism under stress remain unclear. Utilizing 13C6-labeled glucose to trace metabolic pathways, our study investigated the impact of stress by chronic social defeat (CSD) on glucose metabolites in the liver and brain one week post-stress. We observed a reduction in 13C6-enrichment of glucose metabolites in the liver, contrasting with unchanged levels in the brain. Notably, hepatic glycogen levels were reduced while lactate concentrations were elevated, suggesting lactate as an alternative energy source during stress. Long-term effects were also examined, revealing normalized blood glucose levels and restored glycogen stores in the liver three weeks post-CSD, despite sustained increases in food intake. This normalization is hypothesized to result from diminished glucagon levels leading to reduced glycogen phosphorylase activity. Our findings highlight a temporal shift in glucose metabolism, with hyperglycemia and glycogen depletion in the liver early after CSD, followed by a later phase of metabolic stabilization. These results underscore the liver’s critical role in adapting to CSD and provide insights into the metabolic adjustments that maintain glucose homeostasis under prolonged stress conditions.

The effect of anti‐imbalance on glycolipid metabolic homeostasis via the liver–gut axis intervened by 3′‐sialyllactose in obese mice

AbstractSialic acid could ameliorate disorders associated with glycolipid metabolism. 3′‐Sialyllactose (3′‐SL), a type of oligosaccharide, contains sialic acid. We examined the effects of 3′‐SL on glycolipid metabolism in obese mice with high fat diet and explore the underlying mechanisms. A total of 160 male C57BL/6J mice were fed with high‐fat diet for 8 weeks to construct obese mice model. Sixty successfully constructed obese mice were randomly divided three 3′‐SL dosage‐dependent groups, one free sialic acid N‐acetylneuraminic acid (Neu5Ac) group, and one blank control group. Each group of obese mice (n = 12) was continuously supplemented by 3′‐SL or Neu5Ac for 10 weeks. Ten‐week 3′‐SL supplementation and Neu5Ac supplementation both yielded remarkedly lower body weight, reduced fat content, increased energy expenditure and active daily exercises with improved glycolipid biomarkers, and attenuated proinflammation. 3′‐SL increased the colonic abundances of Akkermansia, Lactobacillus, and Solibacillus and reduced those of Enterobacter and Enterococcus. Changes were also observed in colonic and liver transcript and metabolites, which were mainly enriched in glycolipid metabolism, ameliorated immune function, and mitigated inflammatory signals, autophagy, bile acid metabolism, and insulin resistance. Akkermansia and Solibacillus were significantly associated with changes in colonic metabolites and transcriptome genes. The liver bile component and glucose metabolites were significantly correlated with transcriptional gene expression in the aforementioned differential pathways. Therefore, 3′‐SL can enhance the gut microbiota, regulate intestinal immunity and bile acid metabolism, reduce liver oxidative stress and autophagy processes, alleviate chronic inflammation levels, and improve islet function and lower blood sugar levels by acting through the gut–liver axis.

Elucidating the Antiglycation Effect of Creatine on Methylglyoxal-Induced Carbonyl Stress In Vitro.

Advanced glycation end products (AGEs) with multiple structures are formed at the sites where carbonyl groups of reducing sugars bind to free amino groups of proteins through the Maillard reaction. In recent years, it has been highlighted that the accumulation of AGEs, which are generated when carbonyl compounds produced in the process of sugar metabolism react with proteins, is involved in various diseases. Creatine is a biocomponent that is homeostatically present throughout the body and is known to react nonenzymatically with α-dicarbonyl compounds. This study evaluated the antiglycation potential of creatine against methylglyoxal (MGO), a glucose metabolite that induces carbonyl stress with formation of AGEs in vitro. Further, to elucidate the mechanism of the cytoprotective action of creatine, its effect on the accumulation of carbonyl proteins in the cells and the MGO-induced cellular damage were investigated using neuroblastoma cells. The results revealed that creatine significantly inhibits protein carbonylation by directly reacting with MGO, and creatine added to the culture medium suppressed MGO-derived carbonylation of intracellular proteins and exerted a protective effect on MGO-induced cytotoxicity. These findings suggest that endogenous and supplemented creatine may contribute to the attenuation of carbonyl stress in vivo.

Thiamine Deficiency and its Implications on Microvascular Complications of Diabetes Mellitus

Thiamine is the first vitamin discovered and belongs to Vit B family. The main effect seen with thiamine deficiency is Beri-Beri, Wernicke’s encephalopathy, Wernicke-Korsak off syndrome and are considered as a serious condition but often can be reversed. The deficient status of thiamine can also cause varied affects and can overlap with other conditions to exacerbate its potent effects. It is seen that thiamine is necessary for the metabolism of glucose in the form of cofactors, deficiency of which leads to accumulation of toxic glucose metabolites leading to formation of free radicals and oxidative stress. Glucose is not only important for the formation of energy but its improper metabolism proves to have deleterious effects in the body. In this review, an attempt is made to correlate microvascular complications of diabetes with thiamine deficiency and can be discerned that oxidative stress is one of the important factors for the progress of microvascular complications, as well as diabetic ketoacidosis, atherosclerosis and cardiovascular damage in patients with diabetes mellitus and these can be prevented or maintained by optimizing thiamine levels in the body.

Glucose metabolite methylglyoxal induces vascular endothelial cell pyroptosis via NLRP3 inflammasome activation and oxidative stress in vitro and in vivo

Methylglyoxal (MGO), a reactive dicarbonyl metabolite of glucose, plays a prominent role in the pathogenesis of diabetes and vascular complications. Our previous studies have shown that MGO is associated with increased oxidative stress, inflammatory responses and apoptotic cell death in endothelial cells (ECs). Pyroptosis is a novel form of inflammatory caspase-1-dependent programmed cell death that is closely associated with the activation of the NOD-like receptor 3 (NLRP3) inflammasome. Recent studies have shown that sulforaphane (SFN) can inhibit pyroptosis, but the effects and underlying mechanisms by which SFN affects MGO-induced pyroptosis in endothelial cells have not been determined. Here, we found that SFN prevented MGO-induced pyroptosis by suppressing oxidative stress and inflammation in vitro and in vivo. Our results revealed that SFN dose-dependently prevented MGO-induced HUVEC pyroptosis, inhibited pyroptosis-associated biochemical changes, and attenuated MGO-induced morphological alterations in mitochondria. SFN pretreatment significantly suppressed MGO-induced ROS production and the inflammatory response by inhibiting the NLRP3 inflammasome (NLRP3, ASC, and caspase-1) signaling pathway by activating Nrf2/HO-1 signaling. Similar results were obtained in vivo, and we demonstrated that SFN prevented MGO-induced oxidative damage, inflammation and pyroptosis by reversing the MGO-induced downregulation of the NLRP3 signaling pathway through the upregulation of Nrf2. Additionally, an Nrf2 inhibitor (ML385) noticeably attenuated the protective effects of SFN on MGO-induced pyroptosis and ROS generation by inhibiting the Nrf2/HO-1 signaling pathway, and a ROS scavenger (NAC) and a permeability transition pore inhibitor (CsA) completely reversed these effects. Moreover, NLRP3 inhibitor (MCC950) and caspase-1 inhibitor (VX765) further reduced pyroptosis in endothelial cells that were pretreated with SFN. Collectively, these findings broaden our understanding of the mechanism by which SFN inhibits pyroptosis induced by MGO and suggests important implications for the potential use of SFN in the treatment of vascular diseases.

Polyphenol-Rich Aronia melanocarpa Fruit Beneficially Impact Cholesterol, Glucose, and Serum and Gut Metabolites: A Randomized Clinical Trial.

Polyphenol-rich Aronia fruits have great potential as a functional food with anti-inflammatory, hypolipidemic, and hypoglycemic biologic activities. However, clinical intervention trials investigating the impact of Aronia fruit consumption on human health are limited. A randomized, controlled, double-blinded, parallel intervention trial was conducted using 14 human subjects who ingested either 0 mL or 100 mL of Aronia juice daily for 30 days. Anthropometric measurements, fasting, and postprandial measures of glucose and lipid metabolism and inflammation, 16S rRNA fecal microbial composition data, and mass spectrometry-acquired serum and fecal metabolomic data were collected before and after the intervention period. Data were analyzed using general linear models, ANOVA, and t-tests. Daily consumption of Aronia prevented a rise in cholesterol levels (β = -0.50, p = 0.03) and reduced postprandial glucose (β = -3.03, p < 0.01). No difference in microbial community composition by condition was identified at any taxonomic level, but a decrease (β = -18.2, p = 0.04) in microbial richness with Aronia was detected. Serum and fecal metabolomic profiles indicated shifts associated with central carbon and lipid metabolism and decreases in pro-inflammatory metabolites. Our study further informs the development of polyphenol-based dietary strategies to lower metabolic disease risk.

The reactive pyruvate metabolite dimethylglyoxal mediates neurological consequences of diabetes

Complications of diabetes are often attributed to glucose and reactive dicarbonyl metabolites derived from glycolysis or gluconeogenesis, such as methylglyoxal. However, in the CNS, neurons and endothelial cells use lactate as energy source in addition to glucose, which does not lead to the formation of methylglyoxal and has previously been considered a safer route of energy consumption than glycolysis. Nevertheless, neurons and endothelial cells are hotspots for the cellular pathology underlying neurological complications in diabetes, suggesting a cause that is distinct from other diabetes complications and independent of methylglyoxal. Here, we show that in clinical and experimental diabetes plasma concentrations of dimethylglyoxal are increased. In a mouse model of diabetes, ilvb acetolactate-synthase-like (ILVBL, HACL2) is the enzyme involved in formation of increased amounts of dimethylglyoxal from lactate-derived pyruvate. Dimethylglyoxal reacts with lysine residues, forms Nε−3-hydroxy-2-butanonelysine (HBL) as an adduct, induces oxidative stress more strongly than other dicarbonyls, causes blood-brain barrier disruption, and can mimic mild cognitive impairment in experimental diabetes. These data suggest dimethylglyoxal formation as a pathway leading to neurological complications in diabetes that is distinct from other complications. Importantly, dimethylglyoxal formation can be reduced using genetic, pharmacological and dietary interventions, offering new strategies for preventing CNS dysfunction in diabetes.

Glyceraldehyde metabolism in mouse brain and the entry of blood-borne glyceraldehyde into the brain.

D-Glyceraldehyde, a reactive aldehyde metabolite of fructose and glucose, is neurotoxic invitro by forming advanced glycation end products (AGEs) with neuronal proteins. In Alzheimer's disease brains, glyceraldehyde-containing AGEs have been detected intracellularly and in extracellular plaques. However, little information exists on how the brain handles D-glyceraldehyde metabolically or if glyceraldehyde crosses the blood-brain barrier from the circulation into the brain. We injected [U-13C]-D-glyceraldehyde intravenously into awake mice and analyzed extracts of serum and brain by 13C nuclear magnetic resonance spectroscopy. 13C-Labeling of brain lactate and glutamate indicated passage of D-glyceraldehyde from blood to brain and glycolytic and oxidative D-glyceraldehyde metabolism in brain cells. 13C-Labeling of serum glucose and lactate through hepatic metabolism of [U-13C]-D-glyceraldehyde could not explain the formation of 13C-labeled lactate and glutamate in the brain. Cerebral glyceraldehyde dehydrogenase and reductase activities, leading to the formation of D-glycerate and glycerol, respectively, were 0.27-0.28 nmol/mg/min; triokinase, which phosphorylates D-glyceraldehyde to D-glyceraldehyde-3-phosphate, has been demonstrated previously at low levels. Thus, D-glyceraldehyde metabolism toward glycolysis could proceed both through D-glycerate, glycerol, and D-glyceraldehyde-3-phosphate. The aldehyde group of D-glyceraldehyde was overwhelmingly hydrated into a diol in aqueous solution, but the diol dehydration rate greatly exceeded glyceraldehyde metabolism and did not restrict it. We conclude that (1) D-glyceraldehyde crosses the blood-brain barrier, and so blood-borne glyceraldehyde could contribute to AGE formation in the brain, (2) glyceraldehyde is taken up and metabolized by brain cells. Metabolism thus constitutes a detoxification mechanism for this reactive aldehyde, a mechanism that may be compromised in disease states.

Altered bile acid and correlations with gut microbiome in transition dairy cows with different glucose and lipid metabolism status

The transition from pregnancy to lactation is critical in dairy cows. Among others, dairy cows experience a metabolic stress due to a large change in glucose and lipid metabolism. Recent studies revealed that bile acids (BA), other than being involved in both the emulsification and solubilization of fats during intestinal absorption, can also affect the metabolism of glucose and lipids, both directly or indirectly by affecting the gut microbiota. Thus, we used untargeted and targeted metabolomics and 16S rRNA gene sequencing approaches to investigate the concentration of plasma metabolites and BA, the composition of the rectum microbial community, and assess their interaction in transition dairy cows. In Experiment 1, we investigated BA and other blood parameters and gut microbiota in dairy cows without clinical diseases during the transition period, which can be seen as well adapted to the challenge of changed glucose and lipid metabolism. As expected, we detected an increased plasma concentrations of BHB and nonesterified fatty acids (NEFA) but decreased concentrations of glucose, cholesterol, and triglycerides (TG). Untargeted metabolomic analysis of the plasma revealed primary BA biosynthesis was one of the affected pathways, and was consistent with the increased concentration of BA in the plasma. A correlation approach revealed a complex association between BA and microbiota with the host plasma concentration of glucose and lipid metabolites. Among BA, chenodeoxycholic acid derivates such as glycolithocholic acid, taurolithocholic acid, lithocholic acid, taurochenodeoxycholic acid, and taurodeoxycholic acid were the main hub nodes connecting microbe and blood metabolites (such as glucose, TG, and NEFA). In Experiment 2, we investigated early postpartum dairy cows with or without hyperketonemia (HPK). As expected, HPK cows had increased concentration of NEFA and decreased concentrations of glucose and triglycerides. The untargeted metabolomic analysis of the plasma revealed that primary BA biosynthesis was also one of the affected pathways. Even though the BA concentration was similar among the 2 groups, the profiles of taurine-conjugated BA changed significantly. A correlation analysis also revealed an association between BA and microbiota with the concentration in plasma of glucose and lipid metabolites (such as BHB). Among BA, cholic acid and its derivates such as taurocholic acid, tauro α-muricholic acid, and taurodeoxycholic acid were the main hub nodes connecting microbe and blood metabolites. Our results indicated an association between BA, intestinal microbe, and glucose and lipid metabolism in transition dairy cows. These findings provide new insight into the adaptation mechanisms of dairy cows during the transition period.

MODL-05. UNDERSTANDING THE METABOLIC VULNERABILITIES IN INFILTRATING GLIOMATOSIS CEREBRI CELLS

Abstract BACKGROUND Gliomatosis cerebri (GC), a rare form of high-grade glioma, is characterized by a particularly invasive phenotype within multiple lobes of the brain and a dismal prognosis. This entity was removed in 2016 of the WHO brain tumor classification because of an absence of specific GC driving molecular signature. Its diffusive aspect on MRI is defined by an absence of cohesive tumor mass, a mild contrast enhancement and a rare neoangiogenesis. Based on those observations, our objectives were to understand how these cells are adapting to their brain environment without a physiological nutritive efflux associated to a reduced oxygen concentration and determine a metabolic signature of GC. METHODS Preliminary results in a large cohort of HGGs bearing several drivers (H3.3 G34V, NMYC amplified, BCOR positive) or a more “wildtype” phenotype with new entities (pedRTK 1 and 2) were underlining glucose and glutamine as major nutrients in cell metabolic suppliance. Therefore, epigenetic assessments, bulk metabolomics, and Seahorse technology, as well as labeled glucose and glutamine metabolites study, helped us in pediatric GC-derived cell lines (BT97 and BT139, PEDIAMODECAN program) to understand the role of both nutrients and their central role in GC in hypoxic microenvironment. RESULTS Both glucose and glutamine are involved in carbon fueling biosynthesis in those cells. Glutamine is much more involved in supplying nitrogen to fuel several specific amino acids and mitochondrial metabolisms. Meanwhile, we developed drug testing using Matrigel invasion aspects. The tested drugs were able to reduce invasiveness of GC cells and modify the intratumoral metabolism. CONCLUSION All those observations seem to explain GC cell adaptation into the hypoxic microenvironment, their plasticity and resistance through metabolic reprogramming based on glutaminolysis and glycolysis.

Isolation, screening, and characterization of the newly isolated osmotolerant yeast Wickerhamomyces anomalus BKK11-4 for the coproduction of glycerol and arabitol.

This study explored the isolation and screening of an osmotolerant yeast, Wickerhamomyces anomalus BKK11-4, which is proficient in utilizing renewable feedstocks for sugar alcohol production. In batch fermentation with high initial glucose concentrations, W. anomalus BKK11-4 exhibited notable production of glycerol and arabitol. The results of the medium optimization experiments revealed that trace elements, such as H3BO3, CuSO4, FeCl3, MnSO4, KI, H4MoNa2O4, and ZnSO4, did not increase glucose consumption or sugar alcohol production but substantially increased cell biomass. Osmotic stress, which was manipulated by varying initial glucose concentrations, influenced metabolic outcomes. Elevated glucose levels promoted glycerol and arabitol production while decreasing citric acid production. Agitation rates significantly impacted the kinetics, enhancing glucose utilization and metabolite production rates, particularly for glycerol, arabitol, and citric acid. The operational pH dictated the distribution of the end metabolites, with glycerol production slightly reduced at pH 6, while arabitol production remained unaffected. Citric acid production was observed at pH 6 and 7, and acetic acid production was observed at pH 7. Metabolomic analysis using GC/MS identified 29 metabolites, emphasizing the abundance of sugar/sugar alcohols. Heatmaps were generated to depict the variations in metabolite levels under different osmotic stress conditions, highlighting the intricate metabolic dynamics occurring post-glucose uptake, affecting pathways such as the pentose phosphate pathway and glycerolipid metabolism. These insights contribute to the optimization of W. anomalus BKK11-4 as a whole-cell factory for desirable products, demonstrating its potential applicability in sustainable sugar alcohol production from renewable feedstocks.

297 Effects of plasma zinc concentration on longissimus thoracis metabolic status of beef steers

Abstract The objective of this study was to examine the role of Zn status on muscle glucose and other metabolites. Angus steers [n = 144; body weight (BW) = 525 ± 30 kg] with varying plasma Zn concentration and implant status served as the initial pool for this secondary experiment. Steers were assigned to one of two implant (IMP) treatments: no implant (NO) or Component TE-200 (TE-200; Elanco, Greenfield, IN) on d 0. Zinc was supplemented as ZnSO4 at 0 mg Zn/kg dry matter (DM; analyzed 54 mg Zn/kg DM), 30 mg Zn/kg DM, or 100 mg Zn/kg DM, starting 60 d before implant day. Steers were fed via GrowSafe bunks (GrowSafe Systems Ltd., Airdie, AB, Canada), and steer was experimental unit. Steers were fed in two blocks with a 14-d stagger for sample logistics. Blood and muscle biopsies of the longissimus thoracis were collected on d 40 after implant, a minimum of 2 h post-feed delivery. Plasma Zn was quantified via ICP-OES and 144 samples were stratified into quantiles by plasma Zn concentration. Samples (n = 12 low and 12 high from NO and TE-200 groups) were identified and designated as low plasma Zn (LOW, 1.1 mg Zn/L average) and high plasma Zn (HI, 1.6 mg Zn/L average) treatments (TRT). Muscle samples from these 48 steers were homogenized and derivatized for subsequent analysis via gas chromatography-mass spectrometry (GCMS) for non-targeted metabolomic analysis. Data were analyzed as a complete randomized design using the MIXED procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC) with fixed effects of TRT, IMP, BLOCK, and TRT×IMP. A TRT×IMP effect was observed for muscle glycine (P = 0.02) where LOW/IMP was similar to HI/NO but had greater glycine concentrations than LOW/NO and HI/IMP. There was a tendency for a TRT×IMP (P = 0.07) effect where LOW/IMP and HI/NO tended to have greater concentrations of hydroxyisovaleric acid. Given the role of glycine in protein synthesis and hydroxyisovaleric acid in leucine metabolism these data suggest differential protein responses to implants in cattle of lesser vs. greater plasma Zn concentrations. Hydroxybutyric acid, a ketone body which can be utilized for energy, tended to be greater in muscle of steers receiving an IMP (P = 0.09). Contrary to our hypothesis that greater plasma Zn would support differential muscle glucose metabolism, no effects of plasma Zn TRT or IMP were noted for glucose, lactate, and other detected metabolites. Both LOW and HI plasma Zn concentrations were still considered adequate, and future research should explore the impact of distinctly deficient and adequate plasma Zn concentration on glucose metabolism pathways in muscle.

Metabolic dysfunction in the myocardium three months after exertional heat stroke in mice

In humans, exposure to heat stroke has proven to be a risk factor for development of cardiovascular disease later in life. We hypothesized that exposure to exertional heat stroke (EHS) would result in the development of similar long-term cardiac disease in mice. In this study we followed mice for three months after EHS, using ultrasound imaging of the heart, metabolomics and histological analysis of ventricular tissue and biomarker analysis after 4 weeks of recovery. Methods: Mice were instrumented with temperature telemetry devices and were trained to run on forced running wheels using an incremental exercise protocol. EHS mice ran in an temperature elevated environmental chamber; females 37.5°C; males 34°C; whereas, matched exercise control mice (EXC) ran in 22-23°C. Running stopped when EHS mice reached symptom limitation (unconsciousness). The mice were followed for 12 wks post EHS, with two ultrasound measures at 2 and 10 wks of recovery. At the end of the study, mice were anesthetized, a blood sample drawn, and ventricular tissue collected for metabolomics. RESULTS: Male but not female EHS mice gained ~10% greater body mass compared to EXC over the course of recovery ( P&lt;0.01). Hearts from male but not female EHS mice exhibited elevations in heart mass per tibia length ( P&lt;0.01). At three months, metabolomics in male EHS hearts revealed significant elevations in glucose and glucose metabolites and significant decreases in acylcarnitines consistent with a metabolic shift toward glucose and away from lipid metabolism. In contrast, female hearts exhibited fewer abnormalities but with significant elevations in lipid and arachidonate metabolites. At two weeks post, there were no differences in male ultrasound measures between EHS and EXC mice but in females there was a reduced posterior wall velocity ( P=0.012) and a trend towards narrower posterior wall thickness ( P= 0.06) . Between 2 and 12 wks post EHS, there were significant elevations in fractional shortening in males ( P&lt;0.05) and elevations in posterior wall velocity ( P&lt;0.01). In contrast, females exhibited significant reductions posterior wall velocity. From blood samples, male EHS mice had increased HDL and females exhibited decreased HDL (p&lt;0.01 in both). LDL increased only in males P&lt;0.05. Vascular adhesion molecules sICAM ( P&lt;0.01) and Pecam1 ( P&lt;0.01) were significantly decreased in EHS males and females and e-Selectin was decreased in EHS males only ( P&lt;0.001). Total serum protein was significantly reduced in both male and females ( P&lt;0.01). Male EHS mice also exhibited significant elevations in white blood cell count and total lymphocytes ( P=0.01) suggesting ongoing activation of the immune system . CONCLUSIONS: In this controlled preclinical model of EHS, both male and female mice exhibited long-lasting cardiovascular and systemic disorders that could account for the lingering incidence of cardiovascular disease and poor overall health in heat stroke victims. Supported by US Army Med. Research and Devel. Command BA180078 and the BK and Betty Stevens Endowment. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Analysis of Lysine Metabolism in a Rat Model of Type 2 Diabetes Reveals Modulation of Endocytosis and Glucose Metabolism

Lysine is an essential amino acid that serves as a building block for proteins and plays a role in metabolic processes. While a recent study provided evidence that lysine is beneficial for hypertension-associated kidney disease, possibly through inhibiting renal tubular reabsorption and forming new lysine conjugates, knowledge about the role of lysine in diabetic nephropathy (DN) is rudimentary. Therefore, the aim of the study was to investigate the role of lysine in kidney function in the setting of DN and its underlying mechanisms. We hypothesized that lysine may impact the kidneys in the following ways: 1) by mediating protein endocytosis in proximal tubules; 2) by altering protein abundance in the kidneys and other organs; and 3) by disrupting metabolic pathways through the formation of conjugates or degradation products. We investigated the effects of lysine on proximal tubule endocytosis and other organs using proteomic approaches and studied changes in lysine conjugates and metabolic products using targeted metabolomics. The results of urinary proteomics suggested that lysine’s impact on endocytosis may be associated with the inhibition of megalin and cubilin. Furthermore, lysine affected proteins related to glucose metabolism. Subsequently, we proceeded to investigate the influence of lysine on various organs in Type 2 Diabetic Nephropathy (T2DN) rats. Gene Ontology (GO) enrichment revealed that lysine exerts tissue-specific effects on different organs, with pathways enriched in the kidney including phagocytosis and enzyme inhibitor activity. Additionally, within the kidney, the lysine-treated group showed downregulation of glycolysis-related enzymes. The metabolomics results showed that lysine leads to a decrease in glucose and an increase in fructose 1,6-bisphosphate, while also resulting in an upregulation of related metabolites in the tricarboxylic acid cycle (TCA cycle). Our findings showed changes in the protein composition involved in lysine-mediated endocytosis and the impact of lysine on glucose metabolism enzymes and metabolites. The specific molecular mechanisms are still under investigation. R01 DK135644 and I01 BX004024 (to AS). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Citrate, a TCA cycle metabolite, plays a role as a hydroxyl radical scavenger in vitro

Reactive oxygen species, such as superoxide anions, hydrogen peroxide, and hydroxyl radicals, are strongly associated with diseases and aging. Superoxide anions and hydrogen peroxide are scavenged by superoxide dismutase and catalase, respectively. These scavenging reactions are supported by enzymes. In contrast, hydroxyl radicals are scavenged by non-enzymatic compounds, such as ascorbic acid, glutathione, and phenolic compounds. Recently, metabolites of glucose and ethanol have been shown to act as hydroxyl radical scavengers. In this study, we evaluated hydroxyl radical-scavenging activity of metabolites of the TCA cycle. We found that these metabolites have a scavenging activity against hydroxyl radicals. In particular, citrate exhibited significant scavenging activity at the cellular level. Additionally, citrate protected superoxide dismutase from hydroxyl radicals. We also confirmed the protective role of citrate against hydroxyl radical-induced DNA strand breakage. The previously reported rate constants and intracellular concentrations did not rule out a protective role in mitochondria. Collectively, our results indicate that citrate acts as a hydroxyl radical scavenger.

Effects of Ganjianglingzhu Decoction on Lean Non-Alcoholic Fatty Liver Disease in Mice Based on Untargeted Metabolomics.

Non-alcoholic fatty liver disease (NAFLD) is usually associated with obesity. However, it is crucial to recognize that NAFLD can also occur in lean individuals, which is frequently overlooked. Without an approved pharmacological therapy for lean NAFLD, we aimed to investigate whether the Ganjianglingzhu (GJLZ) decoction, a representative traditional Chinese medicine (TCM), protects against lean NAFLD and explore the potential mechanism underlying these protective effects. The mouse model of lean NAFLD was established with a methionine-choline-deficient (MCD) diet in male C57BL/6 mice to be compared with the control group fed the methionine-choline-sufficient (MCS) diet. After four weeks, physiological saline, a low dose of GJLZ decoction (GL), or a high dose of GJLZ decoction (GH) was administered daily by gavage to the MCD group; the MCS group was given physiological saline by gavage. Untargeted metabolomics techniques were used to explore further the potential mechanism of the effects of GJLZ on lean NAFLD. Different doses of GJLZ decoction were able to ameliorate steatosis, inflammation, fibrosis, and oxidative stress in the liver; GL performed a better effect on lean NAFLD. In addition, 78 candidate differential metabolites were screened and identified. Combined with metabolite pathway enrichment analysis, GL was capable of regulating the glucose and lipid metabolite pathway in lean NAFLD and regulating the glycerophospholipid metabolism by altering the levels of sn-3-O-(geranylgeranyl)glycerol 1-phosphate and lysoPC(P-18:0/0:0). GJLZ may protect against the development of lean NAFLD by regulating glucose and lipid metabolism, inhibiting the levels of sn-3-O-(geranylgeranyl)glycerol 1-phosphate and lysoPC(P-18:0/0:0) in glycerophospholipid metabolism.