Low Glycogen Research Articles

Evaluating the impact of gadolinium contamination on the marine bivalve Donax trunculus: Implications for environmental health

Gadolinium (Gd), commonly used in contrast agents for medical imaging, has been detected in hospital wastewater and aquatic environments, raising environmental concerns. This study examined the accumulation and cellular impacts of Gd in the clam species Donax trunculus, commonly used as bioindicator of contamination. Gadolinium accumulation in clams increased with exposure and over time. Biological responses varied with Gd levels: low concentrations (10 and 50 µg/L) led to low metabolic activity and glycogen content, but high antioxidant activities and lipid peroxidation levels (LPO); high concentrations (250 and 500 µg/L) resulted in increased metabolic activity, while antioxidant enzyme activity was inhibited and LPO levels were the lowest. Metabolic activity decreased after two weeks, suggesting limited long-term metabolic resilience. The study underscores D. trunculus as an effective early warning species for Gd pollution and highlights the ecological risks of rising Gd levels, emphasizing the need for environmental monitoring and regulation.

Glucose and glycogen affects Ca2+ transient during fatigue to a greater extent in the least than in the most fatigue resistant mouse FDB fibers.

The overall objective was to determine how no extracellular glucose and/or low glycogen content affect fatigue kinetics in mouse flexor digitorum brevis (FDB) single muscle fibers. High glycogen content (Hi GLY), near normal insitu level, was obtained by incubating fibers in culture medium containing glucose and insulin while low glycogen content (Lo GLY), at about 19% of normal insitu level, was achieved by incubating fibers without glucose. Neither Lo GLY nor the absence of extracellular glucose (0GLU) affected tetanic [Ca2+]i prior to fatigue. The number of contracting unfatigued fibers versus stimulus strength relationship of Lo GLY-0GLU fibers was shifted to higher voltages compared to Hi GLY fibers exposed to 5.5 mM glucose (5GLU). The relationship for Lo GLY-0GLU fibers was shifted back toward that of Hi GLY-5GLU fibers when glucose was reintroduced, whereas the removal of glucose from Hi GLY-5GLU fibers had no effect. Fatigue was elicited with one 200 ms long tetanic contraction every s for 3 min. Both Lo GLY and 0GLU increased the rate at which intracellular tetanic concentration ([Ca2+]i) declined and unstimulated [Ca2+]i increased during fatigue in the order of the least fatigue resistant > mid fatigue resistant > the most fatigue resistant fibers.

Genome-wide identification of the PP1 and PPP1R3 gene family in oyster Crassostrea gigas: Unraveling their roles in glycogen metabolism

High glycogen in oysters contributes to their flavor, quality, and hardiness, making it a crucial target trait for breeding purposes. Until now, the upstream regulatory mechanism for glycogen synthesis has remained unclear. Protein phosphatase-1 regulatory subunit 3 (PPP1R3) is a member of a family that directs the protein phosphatase-1 (PP1) to glycogen, resulting in the activation of glycogen synthase (GS) and the inactivation of glycogen phosphorylase (GP). However, their functions in molluscan species have remained unclear until now. In our study, we verified the function of the PP1α/PPP1R3D pathways in the glycogen metabolism process in Crassostrea gigas. Initially, we conducted a phylogenetic analysis and identified two PP1 and PPP1R3 members in molluscan species, emphasizing copy number variations in eukaryotic animals. Additionally, we identified distinct substitutions of conserved motifs specific to bivalves, Cephalopoda, or Gastropods, revealing functional diversity in PP1 and PPP1R3. Our primary focus was on PP1α/PPP1R3D in the oyster C.gigas, detected in the muscle glycogen fraction of bivalve species, with mRNA expression showing a positive correlation with glycogen content. By manipulating CgPPP1R3D expression in oysters through adenovirus-mediated overexpression or siRNA-mediated downregulation, we established a direct positive correlation between CgPPP1R3D expression levels and glycogen content. Colocation analysis confirmed protein interactions between CgPP1α and CgPPP1R3D. Furthermore, to elucidate the correlation between gene expression and glycogen accumulation, we conducted an association analysis and identified a cluster of significant SNP loci upstream of CgPPP1R3D significantly related to glycogen content. The high polymorphism observed may be linked to differential expressions of CgPPP1R3D in oyster individuals with high and low glycogen levels. These findings serve as a crucial reference for enhancing glycogen traits in molluscan species.

Disrupted H2 synthesis combined with methyl viologen treatment inhibits photosynthetic electron flow to synergistically enhance glycogen accumulation in the cyanobacterium Synechocystis sp. PCC 6803.

Under nitrogen deprivation (-N), cyanobacterium Synechocystis sp. PCC 6803 exhibits growth arrest, reduced protein content, and remarkably increased glycogen accumulation. However, producing glycogen under this condition requires a two-step process with cell transfer from normal to -N medium. Metabolic engineering and chemical treatment for rapid glycogen accumulation can bypass the need for two-step cultivation. For example, recent studies indicate that individually disrupting hydrogen (H2) or poly(3-hydroxybutyrate) (PHB) synthesis, or treatment with methyl viologen (MV), effectively increases glycogen accumulation in Synechocystis. Here we explore the effects of disrupted H2 or poly(3-hydroxybutyrate) synthesis, together with MV treatment to on enhanced glycogen accumulation in Synechocystis grown in normal medium. Wild-type cells without MV treatment exhibited low glycogen content of less than 6% w/w dry weight (DW). Compared with wild type, disrupting PHB synthesis combined with MV treatment did not increase glycogen content. Disrupted H₂ production without MV treatment yielded up to 11% w/w DW glycogen content. Interestingly, when combined, disrupted H2 production with MV treatment synergistically enhanced glycogen accumulation to 51% and 59% w/w DW within 3 and 7days, respectively. Metabolomic analysis suggests that MV treatment mediated the conversion of proteins into glycogen. Metabolomic and transcriptional-expression analysis suggests that disrupted H2 synthesis under MV treatment positively influenced glycogen synthesis. Disrupted H₂ synthesis under MV treatment significantly increased NADPH levels. This increased NADPH content potentially contributed to the observed enhancements in antioxidant activity against MV-induced oxidants, O2 evolution, and metabolite substrates levels for glycogen synthesis in normal medium, ultimately leading to enhanced glycogen accumulation in Synechocystis. KEY MESSAGE: Combining disrupted hydrogen-gas synthesis and the treatment by photosynthesis electron-transport inhibitor significantly enhance glycogen production in cyanobacteria.

Effects of Short-Term Nighttime Carbohydrate Restriction Method on Exercise Performance and Fat Metabolism.

The sleep-low method has been proposed as a way to sleep in a low-glycogen state, increase the duration of low glycogen availability and sleep and temporarily restrict carbohydrates to improve exercise performance. However, long-term dietary restriction may induce mental stress in athletes. Therefore, if it can be shown that the effects of the sleep-low method can be achieved by restricting the carbohydrate intake at night (the nighttime carbohydrate restriction method), innovative methods could be developed to reduce weight in individuals with obesity and enhance athletes' performance with reduced stress and in a shorter duration when compared with those of previous studies. With this background, we conducted a study with the purpose of examining the intervention effects of a short-term intensive nighttime carbohydrate restriction method. A total of 22 participants were recruited among university students participating in sports club activities. The participants were assigned at random to groups, including a nighttime carbohydrate restriction group of 11 participants (6 males, 5 females; age 22.3 ± 1.23) who started a carbohydrate-restricted diet and a group of 11 participants (5 males, 6 females; age 21.9 ± 7.9) who continued with their usual diet. The present study had a two-group parallel design. In the first week, no dietary restrictions were imposed on either group, and the participants consumed their own habitual diets. In the second week, the total amount of calories and carbohydrate intake measured in the first week were divided by seven days, and the average values were calculated. These were used as the daily calorie and carbohydrate intakes in the second week. Only the nighttime carbohydrate restriction group was prohibited from consuming carbohydrates after 4:00 p.m. During the two-week study period, all participants ran for one hour each day before breakfast at a heart rate of 65% of their maximum heart rate. The results obtained from young adults participating in sports showed significant differences in peak oxygen consumption (V·O2peak), work rate max, respiratory quotient (RQ), body weight and lean body mass after the intervention when compared with before the intervention in the nighttime carbohydrate restriction group (p < 0.05). Our findings suggest that the nighttime carbohydrate restriction method markedly improves fat metabolism even when performed for a short period. This method can be used to reduce body weight in individuals with obesity and enhance athletes' performance. However, it is important to consider the intake of nutrition other than carbohydrates.

MiR-141/200c contributes to ethanol-mediated hepatic glycogen metabolism

ObjectiveHepatic glucose metabolism is profoundly perturbed by excessive alcohol intake. miR-141/200c expression is significantly induced by chronic ethanol feeding. This study aimed at identifying the role of miR-141/200c in glucose homeostasis during chronic ethanol exposure. MethodsWT and miR-141/200c KO mice were fed a control or an ethanol diet for 30 days, followed by a single binge of maltose dextrin or ethanol, respectively. Untargeted metabolomics analysis of hepatic primary metabolites was performed along with analyses for liver histology, gene expression, intracellular signaling pathways, and physiological relevance. Primary hepatocytes were used for mechanistic studies. ResultsmiR-141/200c deficiency rewires hepatic glucose metabolism during chronic ethanol feeding, increasing the abundance of glucose intermediates including G6P, an allosteric activator for GS. miR-141/200c deficiency replenished glycogen depletion during chronic ethanol feeding accompanied by reduced GS phosphorylation in parallel with increased expression of PP1 glycogen targeting subunits. Moreover, miR-141/200c deficiency prevented ethanol-mediated increases in AMPK and CaMKK2 activity. Ethanol treatment reduced glycogen content in WT-hepatocytes, which was reversed by dorsomorphin, a selective AMPK inhibitor, while KO-hepatocytes displayed higher glycogen content than WT-hepatocytes in response to ethanol treatment. Furthermore, treatment of hepatocytes with A23187, a calcium ionophore activating CaMKK2, lowered glycogen content in WT-hepatocytes. Notably, the suppressive effect of A23187 on glycogen deposition was reversed by dorsomorphin, demonstrating that the glycogen depletion by A23187 is mediated by AMPK. KO-hepatocytes exhibited higher glycogen content than WT-hepatocytes in response to A23187. Finally, miR-141/200c deficiency led to improved glucose tolerance and insulin sensitivity during chronic ethanol feeding. ConclusionsmiR-141/200c deficiency replenishes ethanol-mediated hepatic glycogen depletion through the regulation of GS activity and calcium signaling coupled with the AMPK pathway, improving glucose homeostasis and insulin sensitivity. These results underscore miR-141/200c as a potential therapeutic target for the management of alcohol intoxication.

Effects of Seasonal Variation in Plumpness, Biochemical Composition from Scallop (Mizuhopecten yessoensis) on Vitality Changes During Dry Storage

ABSTRACT Vitality is a crucial element in the quality control of live scallops. Nevertheless, the effect of energy fluctuations resulting from the reproductive development of scallops on vitality during storage remains unclear. Changes in the biochemical composition of scallops throughout the year were analyzed, and live scallops with high and low glycogen were selected for dry storage. The results showed that glycogen content fluctuations ranged almost 20-fold between the highest and lowest levels. However, the other proximate composition did not change significantly. Notably, scallops with high glycogen exhibited high levels of ATP and maintained more stable vitality during dry storage.

A novel genetic model provides a unique perspective on the relationship between postexercise glycogen concentration and increases in the abundance of key metabolic proteins after acute exercise.

Some acute exercise effects are influenced by postexercise (PEX) diet, and these diet-effects are attributed to differential glycogen resynthesis. However, this idea is challenging to test rigorously. Therefore, we devised a novel genetic model to modify muscle glycogen synthase 1 (GS1) expression in rat skeletal muscle with an adeno-associated virus (AAV) short hairpin RNA knockdown vector targeting GS1 (shRNA-GS1). Contralateral muscles were injected with scrambled shRNA (shRNA-Scr). Muscles from exercised (2-hour-swim) and time-matched sedentary (Sed) rats were collected immediately postexercise (IPEX), 5-hours-PEX (5hPEX), or 9-hours-PEX (9hPEX). Rats in 5hPEX and 9hPEX experiments were refed (RF) or not-refed (NRF) chow. Muscles were analyzed for glycogen, abundance of metabolic proteins (pyruvate dehydrogenase kinase 4, PDK4; peroxisome proliferator-activated receptor γ coactivator-1α, PGC1α; hexokinase II, HKII; glucose transporter 4, GLUT4), AMP-activated protein kinase phosphorylation (pAMPK), and glycogen metabolism-related enzymes (glycogen phosphorylase, PYGM; glycogen debranching enzyme, AGL; glycogen branching enzyme, GBE1). shRNA-GS1 versus paired shRNA-Scr muscles had markedly lower GS1 abundance. IPEX versus Sed rats had lower glycogen and greater pAMPK, and neither of these IPEX-values differed for shRNA-GS1 versus paired shRNA-Scr muscles. IPEX versus Sed groups did not differ for abundance of metabolic proteins, regardless of GS1 knockdown. Glycogen in RF-rats was lower for shRNA-GS1 versus paired shRNA-Scr muscles at both 5hPEX and 9hPEX. HKII protein abundance was greater for 5hPEX versus Sed groups, regardless of GS1 knockdown or diet, and despite differing glycogen levels. At 9hPEX, shRNA-GS1 versus paired shRNA-Scr muscles had greater PDK4 and PGC1α abundance within each diet group. However, the magnitude of PDK4 or PGC1α changes was similar in each diet group regardless of GS1 knockdown although glycogen differed between paired muscles only in RF-rats. In summary, we established a novel genetic approach to investigate the relationship between muscle glycogen and other exercise effects. Our results suggest that exercise-effects on abundance of several metabolic proteins did not uniformly correspond to differences in postexercise glycogen.

The regulation of triglyceride and glycogen storage by Glucose transporter 1 ( Glut1 ) in Drosophila fat tissue.

Obesity reflects an imbalance in nutrient storage resulting in excess fat accumulation. The molecules that tissues use to regulate nutrient storage are not well understood. A previously published genetic screen using Drosophila melanogaster larvae identified Glut1 , a transmembrane glucose transporter, as a potential obesity gene. To identify the adipose-specific functions of this gene, Glut1 levels were decreased using RNAi targeted to fly fat tissue. Adult Glut1 RNAi flies have lower glycogen and triglyceride levels, as well as decreased FASN1 RNA expression. This suggests that Glut1 functions to promote glycogen and triglyceride storage and fatty acid synthesis in Drosophila adipose tissue.

MicroRNA-92b in the skeletal muscle regulates exercise capacity via modulation of glucose metabolism.

Exercise mimetics is a proposed class of therapeutics that specifically mimics or enhances the therapeutic effects of exercise. Muscle glycogen and lactate extrusion are critical for physical performance. The mechanism by which glycogen and lactate metabolism are manipulated during exercise remains unclear. This study aimed to assess the effect of miR-92b on the upregulation of exercise training-induced physical performance. Adeno-associated virus (AAV)-mediated skeletal muscle miR-92b overexpression in C57BLKS/J mice, and global knockout of miR-92b mice were used to explore the function of miR-92b in glycogen and lactate metabolism in skeletal muscle. AAV-mediated UGP2 or MCT4 knockdown in WT or miR-92 knockout mice was used to confirm whether miR-92b regulates glycogen and lactate metabolism in skeletal muscle through UGP2 and MCT4. Body weight, muscle weight, grip strength, running time and distance to exhaustion, and muscle histology were assessed. The expression levels of muscle mass-related and function-related proteins were analysed by immunoblotting or immunostaining. Global knockout of miR-92b resulted in normal body weight and insulin sensitivity, but higher glycogen content before exercise exhaustion (0.8538±0.0417 vs. 1.043±0.040, **P=0.0087), lower lactate levels after exercise exhaustion (4.133±0.2589 vs. 3.207±0.2511, *P=0.0279), and better exercise capacity (running distance to exhaustion, 3616±86.71 vs. 4231±90.29, ***P=0.0006; running time to exhaustion, 186.8±8.027 vs. 220.8±3.156, **P=0.0028), as compared with those observed in the control mice. Mice skeletal muscle overexpressing miR-92b (both miR-92b-3p and miR-92b-5p) displayed lower glycogen content before exercise exhaustion (0.6318±0.0231 vs. 0.535±0.0194, **P=0.0094), and higher lactate accumulation after exercise exhaustion (4.5±0.2394 vs. 5.467±0.1892, *P=0.01), and poorer exercise capacity (running distance to exhaustion, 4005±81.65 vs. 3228±149.8, ***P<0.0001; running time to exhaustion, 225.5±7.689 vs. 163±6.476, **P=0.001). Mechanistic analysis revealed that miR-92b-3p targets UDP-glucose pyrophosphorylase 2 (UGP2) expression to inhibit glycogen synthesis, while miR-92b-5p represses lactate extrusion by directly target monocarboxylate transporter 4 (MCT4). Knockdown of UGP2 and MCT4 reversed the effects observed in the absence of miR-92b in vivo. This study revealed regulatory pathways, including miR-92b-3p/UGP2/glycogen synthesis and miR-92b-5p/MCT4/lactate extrusion, which could be targeted to control exercise capacity.

The potassium-glycogen interaction on force and excitability in mouse skeletal muscle: implications for fatigue.

A reduced muscle glycogen content and potassium (K+ ) disturbances across muscle membranes occur concomitantly during repeated intense exercise and together may contribute to skeletal muscle fatigue. Therefore, we examined whether raised extracellular K+ concentration ([K+ ]o ) (4 to 11 mM) interacts with lowered glycogen to reduce force production. Isometric contractions were evoked in isolated mouse soleus muscles (37°C) using direct supramaximal field stimulation. (1) Glycogen declined markedly in non-fatigued muscle with >2h exposure in glucose-free physiological saline compared with control solutions (11 mM glucose), i.e. to <45% control. (2) Severe glycogen depletion was associated with increased 5'-AMP-activated protein kinase activity, indicative of metabolic stress. (3) The decline of peak tetanic force at 11mM [K+ ]o was exacerbated from 67% initial at normal glycogen to 22% initial at lowered glycogen. This was due to a higher percentage of inexcitable fibres (71% vs. 43%), yet without greater sarcolemmal depolarisation or smaller amplitude action potentials. (4) Returning glucose while at 11mM [K+ ]o increased both glycogen and force. (5) Exposure to 4mM [K+ ]o glucose-free solutions (15 min) did not increase fatiguability during repeated tetani; however, after recovery there was a greater force decline at 11mM [K+ ]o at lower than normal glycogen. (6) An important exponential relationship was established between relative peak tetanic force at 11mM [K+ ]o and muscle glycogen content. These findings provide direct evidence of a synergistic interaction between raised [K+ ]o and lowered muscle glycogen as the latter shifts the peak tetanic force-resting EM relationship towards more negative resting EM due to lowered sarcolemmal excitability, which hence may contribute to muscle fatigue. KEY POINTS: Diminished muscle glycogen levels and raised extracellular potassium concentrations ([K+ ]o ) occur simultaneously during intense exercise and together may contribute to muscle fatigue. Prolonged exposure of isolated non-fatigued soleus muscles of mice to glucose-free physiological saline solutions markedly lowered muscle glycogen levels, as does fatigue then recovery in glucose-free solutions. For both approaches, the subsequent decline of maximal force at 11mM[K+ ]o , which mimics interstitial [K+ ] levels during intense exercise, was exacerbated at lowered compared with normal glycogen. This was mainly due to many more muscle fibres becoming inexcitable. We established an important relationship that provides evidence of a synergistic interaction between raised [K+ ]o and lowered glycogen content to reduce force production. This paper indicates that partially lowered muscle glycogen (and/or metabolic stress) together with elevated interstitial [K+ ] interactively lowers muscle force, and hence may diminish performance especially during repeated high-intensity exercise.

SAT159 A Unique Case Of IGF-2 Induced Hypoglycemia As First Manifestation Of Hepatocellular Carcinoma

Abstract Disclosure: I. Ali: None. M. Alnaher: None. A. Arida: None. Introduction: Hypoglycemia is one of the manifestations of non-islet cell tumor-induced hypoglycemia (NICTH). In hepatocellular carcinoma (HCC), it has been reported in 4-27% of patients, and it is associated with poor prognosis. Case: Patient is a 70-years-old Female with past medical history of prediabetes and untreated Hepatitis C infection who presented with sever weakness and was found to have blood glucose of 37. She was started on Dextrose 10% with improvement of her symptoms. During hospital course she had recurrent episodes of symptomatic hypoglycemia. Patient denied any family history of diabetes with no access to diabetes medication. Blood work showed elevated AST, ALT with low albumin, low prealbumin and AM cortisol 13, Sulfonylureas screen is Negative. Result of 72 hours hypoglycemia protocol while blood glucose level was 48 mg/dl as follow: Proinsulin, Intact 1.6 mmol/L (Ref: less than 8.0), insulin like growth factor -1 (IGF-1): 10 ng/ml (26-226), IGF-2: 69 ng/ml (180-580) so IGF-2/IGF-1 ratio of 6.9Insulin: 0.2 uIU/ml (1.9-23), C-Peptide 0.1 ng/ml (0.5-3.3) and Beta hydroxybutyrate: 0.1 mmol/L. CT abdomen: 7.0 x 7.2 x 10.5 cm right hepatic lobe mass with extension to right portal vein that is most consistent with hepatocellular carcinoma with background liver cirrhosis with portal hypertension without ascites. Right hepatic artery tumor biopsy showed moderately differentiated HCC. Patient was started on steroid therapy then octreotide. Multidisciplinary meeting discussed in details treatment options and prognosis including treatment of her cancer with surgery vs chemoradiation therapy, but patient and her family opted for DNR/DNI, and patient passed away during that admission. Discussion: Even though HCC-related hypoglycemia is a known phenomenon, knowledge about prevention and treatment is lacking. The suggested mechanism of hypoglycemia in NICTH include increased consumption of glucose by tumor in malnourished patients with low glycogen deposits and defective gluconeogenesis or may be caused by IGF-2 overproduction that crosses capillary membranes and stimulates insulin receptor. Hypoglycemia work up reveals low levels of insulin, pro-insulin, C-peptide, and β-hydroxybutyrate. Levels of GH and IGF-1 will also be low due to the suppressive effect of IGF-2. Total IGF-2 may be elevated or normal but the ratio of IGF-2/IGF-1 is usually elevated 3:1. Management of an IGF-2 producing tumor with surgical resection, radiation, and/or chemotherapy can potentially resolve hypoglycemia. Medical therapy with glucocorticoids has been utilized by promoting hepatic gluconeogenesis and lipolysis and reducing peripheral glucose uptake. Glucocorticoids also help to decrease the levels of IGF-2 either by decreased tumor production or increased clearance. Case reports have documented the use of glucagon, growth hormone, and octreotide, however, effects are limited. Presentation: Saturday, June 17, 2023

THU373 Refractory Hypoglycemia In A Patient With Metastatic Cholangiocarcinoma: Abstract

Abstract Disclosure: M.G. Fernandez: None. D.J. Selen: None. Background: Nonislet cell tumor hypoglycemia is an uncommon but severe complication of cancer. It results from tumoral overproduction of insulin-like growth factor 2 (IGF-2), which inhibits hepatic glycogenolysis and the release of glucagon and growth hormone (GH). These three mechanisms can result in severe and refractory hypoglycemia. Clinical Case: We present a case of a 57-year-old female newly diagnosed with metastatic cholangiocarcinoma who was admitted to the hospital after an episode of syncope at home in the setting of hypoglycemia with a serum blood glucose of 17 mg/dL (N &amp;gt;60 mg/dL). During the hospital admission, evaluation of hypoglycemia included a normal TSH of 1.170 (reference range [RR] 0.3-5.5 mIU/ml), fasting morning cortisol of 23.3 (RR &amp;gt;14-15 μg/dL), and a negative sulfonylurea screen. In addition, the patient had an undetectable level of Insulin &amp;lt;3.0 (RR 3-25 mU/L), Beta-hydroxybutyrate &amp;lt;0.10 (RR 0.02-0.27 mMol/L), C-peptide &amp;lt;0.1 (RR 0.5-3.3 ng/ml), and Pro-insulin &amp;lt;1.6 (RR 3-20 pmol/L). CT of the abdomen revealed disease progression with innumerable bilateral enhanced hypoattenuating masses in the liver. Management for refractory hypoglycemia required nutrition optimization, nausea control, close glucose monitoring, IV dextrose infusion, and intermittent intravenous glucagon for episodes of severe hypoglycemia (&amp;lt;40 mg/dL). During the hospitalization, the patient received the first cycle of chemotherapy with gemcitabine, cisplatin, and dexamethasone. On day 10 of admission, the IGF-2 resulted at 120 ng/ml (RR 180-580ng/ml) and IGF-1&amp;lt;10 (RR 50-317 ng/ml) with an IGF-2/IGF-1 ratio greater than 100 (cut off&amp;gt;10), diagnostic of a large nonislet cell tumor as the most likely cause of her severe hypoglycemia. Artificial nutrition did not align with this patient’s goals of care, so she was discharged from the hospital with a FreeStyle Libre 2 for continuous glucose monitoring. However, two weeks later, she returned to the emergency department with hypoglycemia (&amp;lt;40 mg/dL), ultimately choosing to pursue hospice. Conclusion: Patients with large liver tumor burden can experience hypoglycemia due to low glycogen content in the liver. In addition, these patients can have decreased oral intake and weight loss, which confounds the clinical scenario and can delay diagnostic workup. Patients with refractory hypoglycemia and nonislet cell tumors require further evaluation for IGF-2 production, and alternative temporary nutritional options should be discussed with the patient immediately. Therapeutic options depend on the ability to treat underlying cancer. Palliative chemotherapy, surgery, or radiation can be considered to control the tumor and improve hypoglycemia for quality of life when the cancer is otherwise untreatable. Presentation: Thursday, June 15, 2023

Metagenomics, metatranscriptomics, and proteomics reveal the metabolic mechanism of biofilm sequencing batch reactor with higher phosphate enrichment capacity under low phosphorus load

The biofilm sequencing batch reactor (BSBR) process has higher phosphate recovery efficiency and enrichment multiple when the phosphorus load is lower, but the mechanism of phosphate enrichment at low phosphorus load remains unclear. In this study, we operated two BSBR operating under low and high phosphorus load (0.012 and 0.032 kg/(m3·d)) respectively, and used metagenomic, metatranscriptomic, and proteomics methods to analyze the community structure of the phosphorus accumulating organisms (PAOs) in the biofilm, the transcription and protein expression of key functional genes and enzymes, and the metabolism of intracellular polymers. Compared with at high phosphorus load, the BSBR at low phosphorus load have different PAOs and fewer types of PAOs, but in both cases the PAOs must have the PHA, PPX, Pst, and acs genes to become dominant. Some key differences in the metabolism of PAOs from the BSBR with different phosphorus load can be identified as follows. When the phosphorus load is low, the adenosine triphosphoric acid (ATP) and NAD(P)H in the anaerobic stage come from the TCA cycle and the second half of the EMP pathway. The key genes that are upregulated include GAPDH, PGK, ENO, ppdk in the EMP pathway, actP in acetate metabolism, phnB in polyhydroxybutyrate (PHB) synthesis, and aceA, mdh, sdhA, and IDH1 in the TCA cycle. In the meantime, the ccr gene in the PHV pathway is inhibited. As a result, the metabolism of the PAOs features low glycogen with high PHB, Pupt, Prel, and low PHV. That is, more ATP and NAD(P)H flow to phosphorus enrichment metabolism, thus allowing the highly efficient enrichment of phosphorus from low concentration phosphate thanks to the higher abundance of PAOs. The current results provide theoretical support and a new technical option for the enrichment and recovery of low concentrations of phosphate from wastewater by the BSBR process.

Morphologic characteristic of rat myocardium in comorbid pathology

Diabetic cardiomyopathy is a serious complication of diabetes mellitus (DM). Aim. Therefore, we aimed to study myocardial changes in adult rats with streptozotocin (STZ)-induced DM exposed to chronic immobilization stress (CIS). Materials and methods. A total of 26 adult albino male rats weighing 180–200 g were examined. All the animals were divided into three groups: Group I included 10 rats with STZ-induced DM exposed to CIS; Group II comprised 10 rats with STZ-induced DM; Group III included 6 intact animals. The samples were collected on the 14th and 56th days of the experiment. Histological, histochemical, electron microscopy, and biochemical methods were used. Results. On the 14th day of the experiment, in Group I and Group II, increased blood flow was observed in the capillaries, venules, and veins, while an arteriolar spasm in the microcirculation was found. In addition, cardiomyocyte surface area in different myocardial regions reduced due to low glycogen content as confirmed by histochemical and ultrastructural studies. On the 56th day of the experiment, in Group I and Group II, hyperemia occurred due to red blood cell aggregation and microthrombi. The surface area of all microcirculatory vessels increased as compared to that of intact animals, as evidenced by an increase in their wall surface area leading to an increase in their wall-to-lumen ratio. Such morphometric changes in the microcirculatory vessels were indicative of decreased vascular permeability and impaired myocardial blood flow. At the histological level, in Group I and Group II, focal cardiomyocyte lysis, moderate to diffuse stromal edema, lymphohistiocytic infiltration were seen. Such changes pointed to sterile inflammation, probably due to myocardial infraction secondary to diabetic microangiopathy. In cardiomyocytes, karyolysis, vacuolar degeneration, apical ballooning, subsarcolemmic edema, fibrosis and lysis of myofibrils, colliquative necrosis were observed. Conclusions. STZ-induced DM and stress resulted in pronounced destructive changes in the myocardium of rats, including interstitial edema, focal cardiosclerosis, myolysis. Such changes occurred on the background developing diabetic microangiopathy. The most pronounced myocardial changes were recorded in animals with a comorbidity.

Correlation study of SNP of glycogen degradation metabolism related genes and glycogen content in Haliotis discus hannai

Glycogen is an essential nutritional component of the Pacific abalone (Haliotis discus hannai), and its content is a crucial factor in selecting and breeding high-quality abalone. Glycogen catabolism is facilitated by two key enzymes: glycogen debranching enzyme (GDE) and glycogen phosphorylase (GP). This study aimed to explore the relationship between GDE and GP gene polymorphisms and glycogen content in abalone. To this end, four and two SNP loci located in the exonic regions of these two genes, respectively, were screened and identified in 264 abalone using direct sequencing. The results of genetic polymorphism and correlation analysis revealed a negative correlation between the expression of GDE and GP and glycogen content. Moreover, the study found that the GA haplotype of GDE gene SNP1/3 was significantly associated with high glycogen content, while the TT genotype of GP gene SNP2 was significantly associated with low glycogen content. These results provide molecular markers that could be utilized for selecting and breeding glycogen traits in abalone, indicating the potential influence of GDE and GP polymorphisms on glycogen content.

Impact of the carbon flux regulator protein pirC on ethanol production in engineered cyanobacteria.

Future sustainable energy production can be achieved using mass cultures of photoautotrophic microorganisms such as cyanobacteria, which are engineered to synthesize valuable products directly from CO2 and sunlight. For example, strains of the model organism Synechocystis sp. PCC 6803 have been generated to produce ethanol. Here, we performed a study to prove the hypothesis that carbon flux in the direction of pyruvate is one bottleneck to achieve high ethanol titers in cyanobacteria. Ethanol-producing strains of the cyanobacterium Synechocystis sp. PCC 6803 were generated that bear mutation in the gene pirC aiming to increase carbon flux towards pyruvate. The strains were cultivated at different nitrogen or carbon conditions and the ethanol production was analysed. Generally, a clear correlation between growth rate and ethanol production was found. The mutation of pirC, however, had only a positive impact on ethanol titers under nitrogen depletion. The increase in ethanol was accompanied by elevated pyruvate and lowered glycogen levels indicating that the absence of pirC indeed increased carbon partitioning towards lower glycolysis. Metabolome analysis revealed that this change in carbon flow had also a marked impact on the overall primary metabolism in Synechocystis sp. PCC 6803. Deletion of pirC improved ethanol production under specific conditions supporting the notion that a better understanding of regulatory mechanisms involved in cyanobacterial carbon partitioning is needed to engineer more productive cyanobacterial strains.

Combining albumin deficiency and acute exercise reduces hepatic lipid droplet size in mice

Hepatic lipid droplets (LDs) are implicated in ectopic lipid accumulation. The core of LDs, triacylglycerol (TAG), is synthesized from the esterification of fatty acids to a glycerol-3-phosphate (G-3-P) backbone. Albumin transports plasma free fatty acids, and previously albumin knockout (Alb−/−) mice were shown to exhibit lower hepatic TAG levels than wildtype (WT). Exercise is a beneficial strategy to alter hepatic metabolism, but its impacts on reducing hepatic lipids are far from satisfactory. The aim of this study was to investigate the combined effect of albumin deficiency and acute exercise on hepatic LDs. Eight-week-old male Alb−/− and WT mice were divided into sedentary and exercise groups. Exercised mice performed a 30-min high-intensity exercise bout. Results showed that sedentary Alb−/− mice had smaller hepatic LDs (P < 0.0001), associated with mitochondria, while WT mice exhibited larger LDs, surrounded by glycogen granules. Following acute exercise, hepatic LDs in Alb−/− mice reduced by 40% in size, while in WT increased by 14% (P < 0.0001). The maintenance of WT hepatic LDs was associated with elevated G-3-P level (P < 0.05), potentially derived from glycogen (R = -0.32, %change in glycogen versus LD content, P < 0.05). The reduction in Alb−/− mice LDs after exercise was possibly due to their low glycogen level. In conclusion, Alb−/− mice exhibited an enhanced capacity for reducing hepatic LD size and content in response to exercise. These findings suggest that modulating albumin’s functions combined with exercise could be a potential strategy to reduce ectopic lipid deposition in the liver.

1556-P: Hepatic AMP-Activated Protein Kinase Governs Adaptations in Liver Glucose Fluxes and Lipid Homeostasis in Response to Exercise Training in Mice

During acute exercise the liver increases glycogenolysis and the energetically costly process of gluconeogenesis to supply glucose to the working muscle. In response to exercise training, the liver undergoes adaptations in glucose and lipid metabolic pathways to more effectively meet the ATP demand of the next exercise bout. We tested the hypothesis that the energy sensor and master regulator of ATP provision, AMP-activated protein kinase (AMPK), is necessary for liver glucose and lipid adaptations to exercise training. This was accomplished by studying mice with liver-specific deletion of AMPK α1 and α2 subunits (KO) and wild type (WT) littermates undergoing sedentary and exercise training protocols. In vivo isotope infusions combined with 2H/13C metabolic flux analysis quantified liver nutrient fluxes at rest and during treadmill running. Liver metabolite concentrations and the expression of molecular regulators of liver nutrient metabolism were evaluated. The results of this study showed that liver glycogen deposition in response to exercise training was impaired in KO compared to WT mice and that this lower glycogen availability resulted in diminished glycogenolysis, glucose production, and circulating glucose during acute exercise. Exercise training decreased liver diacylglycerides (DAGs) in both genotypes, however, the response was less pronounced in KO mice. Moreover, exercise training led to higher liver triacylglycerides (TAGs) in KO mice. A lack of AMPK action prevented exercise training from promoting the desaturation of DAG fatty acyl chains as evidenced by higher 16:1/16:0 and 18:1/18:0 ratios in KO mice. Unexpectedly, the differences in DAG fatty acyl chain composition between genotypes were not observed in TAGs. Together, these results suggest that AMPK is a critical regulator of the liver glycogen and lipid availability and selectively remodels DAG fatty acyl chain composition in response to exercise training. Disclosure C.C.Hughey: None. D.Bracy: None. L.Lantier: None. M.Foretz: None. B.Viollet: None. D.Wasserman: None. Funding National Institutes of Health (DK050277, DK054902, DK059637, DK020593)

1580-P: Role of Hepatic Glycogen on Nocturnal Gluconeogenesis in Type 2 Diabetes

Higher gluconeogenesis (GNG) during the latter part of the night contributes to higher endogenous glucose production (EGP) in type 2 diabetes (T2D). We have shown that glycogen synthesis is reduced in T2D due to a functional defect in the rate-limiting hepatic glucokinase activity. Studies using MRIs have confirmed lower net hepatic glycogen content in T2D than subjects without diabetes (ND) before and after dinner. We hypothesize that increasing post dinner hepatic glycogen content might restore overnight EGP in T2D by reducing GNG. 14 T2D and 15 anthropometrically matched ND were randomly assigned to glycogen loading (GL; 60% carb) vs. non glycogen loading (NGL; 40% carb) meals for 3 days. [6,6-2H2] Glucose was infused to measure EGP. GNG was estimated with deuterium labeled water and glycogen content measured via C13 NMR in fed and fasted state. Results are shown in Figure1. Liver glycogen content was higher with GL vs NGL in both cohorts. EGP was higher (p&amp;lt;0.05) in GL vs NGL throughout night in both cohorts. The percent contribution of GNG and glycogenolysis (GGL) to EGP averaged ~ 50% in ND throughout the night in both GL and NGL. In contrast, the percent contribution of GNG to EGP in T2D with GL was lower vs. NGL overnight (average ~48% vs. 60%) and matched the pattern observed in ND with GL. The results indicate that lower glycogen content in the liver contributes to increased nocturnal rates of GNG in T2D. Disclosure U.Unni: None. Y.Yadav: None. J.P.Mugler, iii: None. R.Carter: None. A.Basu: None. R.Basu: Consultant; Sparrow Pharmaceuticals Inc, Research Support; Abbott Diabetes, AstraZeneca. Funding National Institute for Health and Care Research (R01DK029953)