ATP Utilization Research Articles

Bioenergetic stress potentiates antimicrobial resistance and persistence.

Antimicrobial resistance (AMR) is a global health crisis and there is an urgent need to better understand AMR mechanisms. Antibiotic treatment alters several aspects of bacterial physiology, including increased ATP utilization, carbon metabolism, and reactive oxygen species (ROS) formation. However, how the "bioenergetic stress" induced by increased ATP utilization affects treatment outcomes is unknown. Here we utilized a synthetic biology approach to study the direct effects of bioenergetic stress on antibiotic efficacy. We engineered a genetic system that constitutively hydrolyzes ATP or NADH in Escherichia coli. We found that bioenergetic stress potentiates AMR evolution via enhanced ROS production, mutagenic break repair, and transcription-coupled repair. We also find that bioenergetic stress potentiates antimicrobial persistence via potentiated stringent response activation. We propose a unifying model that antibiotic-induced antimicrobial resistance and persistence is caused by antibiotic-induced. This has important implications for preventing or curbing the spread of AMR infections.

NSD2 drives t(4;14) myeloma cell dependence on adenylate kinase 2 by diverting one-carbon metabolism to the epigenome

AbstractChromosomal translocation (4;14), an adverse prognostic factor in multiple myeloma (MM), drives overexpression of the histone methyltransferase nuclear receptor binding SET domain protein 2 (NSD2). A genome-wide CRISPR screen in MM cells identified adenylate kinase 2 (AK2), an enzyme critical for high-energy phosphate transfer from the mitochondria, as an NSD2-driven vulnerability. AK2 suppression in t(4;14) MM cells decreased nicotinamide adenine dinucleotide phosphate (NADP[H]) critical for conversion of ribonucleotides to deoxyribonucleosides, leading to replication stress, DNA damage, and apoptosis. Driving a large genome-wide increase in chromatin methylation, NSD2 overexpression depletes S-adenosylmethionine, compromising the synthesis of creatine from its precursor, guanidinoacetate. Creatine supplementation restored NADP(H) levels, reduced DNA damage, and rescued AK2-deficient t(4;14) MM cells. As the creatine phosphate shuttle constitutes an alternative means for mitochondrial high-energy phosphate transport, these results indicate that NSD2-driven creatine depletion underlies the hypersensitivity of t(4;14) MM cells to AK2 loss. Furthermore, AK2 depletion in t(4;14) cells impaired protein folding in the endoplasmic reticulum, consistent with impaired use of mitochondrial adenosine triphosphate (ATP). Accordingly, AK2 suppression increased the sensitivity of MM cells to proteasome inhibition. These findings delineate a novel mechanism in which aberrant transfer of carbon to the epigenome creates a metabolic vulnerability, with direct therapeutic implications for t(4;14) MM.

Evidence of an intracellular creatine-sensing mechanism that modulates creatine biosynthesis via AGAT expression in human HAP1 cells

Cellular homeostasis of creatine (CT), integral part of the energy buffering and transducing system connecting intracellular sites of ATP production and utilization, comprises of mechanisms that increase CT, i.e., biosynthesis and cellular uptake, and CT-lowering processes, such as export and non-enzymatic conversion to creatinine. The biosynthesis of CT is controlled by negative feedback loop via suppression of the rate-limiting enzyme arginine:glycine amidinotransferase (AGAT). Although the regulatory mechanism involved is not well understood, AGAT suppression is successfully used in patients with guanidinoacetate methyltransferase (GAMT) deficiency to reduce the neurotoxic accumulation of the AGAT-mediated guanidinoacetate production by supplementing patients with CT. Utilizing the CT-dependent feedback loop for the upregulation of AGAT expression may well represent a therapeutic target for an additional CT deficiency syndrome, the CT transporter (CrT) defect, for which no effective treatment option is available so far. We have used CRISPR to tag the C-terminus of AGAT with a nanoluc luciferase (NLuc) reporter in HAP1 cells. A biphasic decay of AGAT-NLuc in response to increasing extracellular CT was observed, whereas the decrease in AGAT-NLuc expression was directly proportional to the rise in intracellular CT levels with an approximate IC50 of 1–2 mM. CRISPR generated HAP1 CrT null cells and HAP1 CrT null cells stably expressing a CrT-GFP fusion protein further demonstrated that the biphasic response to extracellular CT is mediated by a high-affinity (Km 9–10 µM) CrT dependent, saturable mechanism and a CrT independent, unsaturable uptake process. The direct response to intracellular CT suggests the existence of an intracellular CT sensing system enabling a dynamic cell response to changing CT concentration that is relevant for cellular CT homeostasis.

The potential mechanism of response to light intensity in energy metabolism mediated by miRNA in Isatis indigotica

Light is the main source of energy for plant growth. Studies have shown that I. indigotica is a light-demanding plant and its yield and various active components are positively correlated with light intensity, but no studies of light intensity affecting energy metabolism in I. indigotica have been reported. Mitochondria are the main site of energy metabolism, and miRNAs are important factors in regulating gene expression, this experiment attempts to study the effects of different light intensities on energy metabolism from the perspective of mitochondria and miRNAs. The results show that the biomass、mitochondrial structural integrity and energy metabolism in I. indigotica were found to be positively correlated with light intensity. Small RNA and transcriptome sequencing identified 241 miRNAs and 36,372 mRNAs, and degradomic technology identified 72 miRNAs targeting 106 mRNAs, among which 12 pairs of miRNA-mRNAs were annotated on mitochondria. Combined with RT-qPCR validation, it was concluded that miR167a-5p positively regulates LETM1 and affects mitochondrial structure, miR400-5p and mIR169m-p3_1ss15CT negatively regulate GRXS15 and CMC4, respectively, affecting SDH and CCO activities, and miR395a-APS4 may affect the utilization of ATP and sulfate assimilation. In summary, the results of this study complement and enrich knowledge of light effects on mitochondria from the perspective of miRNA, while providing guidance for the cultivation of I. indigotica.

Fabrication and characterisation of human gut microbiome derived exopolysaccharide mediated silver nanoparticles – An in-vitro and in-vivo approach of Bio-Pm-AgNPs targeting Vibrio cholerae

Utilising bacteria to produce silver nanoparticles was highly favoured due to its ability to minimise costs and mitigate any potential negative environmental impact. Exopolysaccharides (EPS) extracted from the human gut microbe have demonstrated remarkable efficacy in combating various bacterial infections. Exopolysaccharide (EPS), a naturally occurring biomolecule found in the human gut isolate Proteus mirabilis DMTMMR-11, was characterised using analytical techniques such as Fourier transform infrared spectroscopy (FTIR), 1H-nuclear magnetic resonance, 13C-nuclear magnetic resonance (NMR), and chemical composition analysis, which confirms the presence of carbohydrates (81.03 ± 0.23), proteins (4.22 ± 1.2), uronic acid (12.1 ± 0.12), and nucleic acid content (2.44 ± 0.15) in exopolysaccharide. The one factor at a time (OFAT) and response surface methodology (RSM) – central composite design (CCD) approaches were used to optimise the production of Bio-Pm-AgNPs, leading to an increase in yield of up to 1.86 g/l. The Bio-Pm-AgNPs were then subjected to Fourier transform infrared spectroscopy (FTIR) which determines the functional groups, X-ray diffractometer confers that Bio-Pm-AgNPs are crystalline in nature, field emission-scanning electron microscopy (FE-SEM) reveals the morphology of Bio-Pm-AgNPs, energy dispersive X-ray spectroscopy (EDX) confirms the presence of elements like Ag, C and O, high-resolution transmission electron microscopy (HR-TEM) determines that the Bio-Pm-AgNPs are sphere-shaped at 75 nm. Dynamic light scattering (DLS) and zeta potential analysis were also carried out to reveal the physiological nature of Bio-Pm-AgNPs. Bio-Pm-AgNPs have a promising effect on the inhibitory mechanism of Vibrio cholerae cells at a MIC concentration of 20 μg/ml which significantly affects cellular respiration and energy metabolism through glycolysis and TCA cycles by deteriorating the enzyme responsible for ATP and NADH utilisation. The action of Bio-Pm-AgNPs reduces the purity and concentration of nucleic acids, which leads to higher DNA damage. In-vivo analysis reveals that the treatment of Bio-Pm-AgNPs decreased the colonisation of V. cholerae and improved the survival rates in C. elegans.

Calculation of ATP production rates using the Seahorse XF Analyzer.

Oxidative phosphorylation and glycolysis are the dominant ATP-generating pathways in mammalian metabolism. The balance between these two pathways is often shifted to execute cell-specific functions in response to stimuli that promote activation, proliferation, or differentiation. However, measurement of these metabolic switches has remained mostly qualitative, making it difficult to discriminate between healthy, physiological changes in energy transduction or compensatory responses due to metabolic dysfunction. We therefore present a broadly applicable method to calculate ATP production rates from oxidative phosphorylation and glycolysis using Seahorse XF Analyzer data and empirical conversion factors. We quantify the bioenergetic changes observed during macrophage polarization as well as cancer cell adaptation to in vitro culture conditions. Additionally, we detect substantive changes in ATP utilization upon neuronal depolarization and T cell receptor activation that are not evident from steady-state ATP measurements. This method generates a single readout that allows the direct comparison of ATP produced from oxidative phosphorylation and glycolysis in live cells. Additionally, the manuscript provides a framework for tailoring the calculations to specific cell systems or experimental conditions.

The Novel Role of Mitochondrial Citrate Synthase and Citrate in the Pathophysiology of Alzheimer's Disease.

Citrate synthase is a key mitochondrial enzyme that utilizes acetyl-CoA and oxaloacetate to form citrate in the mitochondrial membrane, which participates in energy production in the TCA cycle and linked to the electron transport chain. Citrate transports through a citrate malate pump and synthesizes acetyl-CoA and acetylcholine (ACh) in neuronal cytoplasm. In a mature brain, acetyl-CoA is mainly utilized for ACh synthesis and is responsible for memory and cognition. Studies have shown low citrate synthase in different regions of brain in Alzheimer's disease (AD) patients, which reduces mitochondrial citrate, cellular bioenergetics, neurocytoplasmic citrate, acetyl-CoA, and ACh synthesis. Reduced citrate mediated low energy favors amyloid-β (Aβ) aggregation. Citrate inhibits Aβ25-35 and Aβ1-40 aggregation in vitro. Hence, citrate can be a better therapeutic option for AD by improving cellular energy and ACh synthesis, and inhibiting Aβ aggregation, which prevents tau hyperphosphorylation and glycogen synthase kinase-3 beta. Therefore, we need clinical studies if citrate reverses Aβ deposition by balancing mitochondrial energy pathway and neurocytoplasmic ACh production. Furthermore, in AD's silent phase pathophysiology, when neuronal cells are highly active, they shift ATP utilization from oxidative phosphorylation to glycolysis and prevent excessive generation of hydrogen peroxide and reactive oxygen species (oxidative stress) as neuroprotective action, which upregulates glucose transporter-3 (GLUT3) and pyruvate dehydrogenase kinase-3 (PDK3). PDK3 inhibits pyruvate dehydrogenase, which decreases mitochondrial-acetyl-CoA, citrate, and cellular bioenergetics, and decreases neurocytoplasmic citrate, acetyl-CoA, and ACh formation, thus initiating AD pathophysiology. Therefore, GLUT3 and PDK3 can be biomarkers for silent phase of AD.

Divalent metal cofactors differentially modulate RadA-mediated strand invasion and exchange in Saccharolobus solfataricus.

Central to the universal process of recombination, RecA family proteins form nucleoprotein filaments to catalyze production of heteroduplex DNA between substrate ssDNAs and template dsDNAs. ATP binding assists the filament in assuming the necessary conformation for forming heteroduplex DNA, but hydrolysis is not required. ATP hydrolysis has two identified roles which are not universally conserved: promotion of filament dissociation and enhancing flexibility of the filament. In this work, we examine ATP utilization of the RecA family recombinase SsoRadA from Saccharolobus solfataricus to determine its function in recombinase-mediated heteroduplex DNA formation. Wild-type SsoRadA protein and two ATPase mutant proteins were evaluated for the effects of three divalent metal cofactors. We found that unlike other archaeal RadA proteins, SsoRadA-mediated strand exchange is not enhanced by Ca2+. Instead, the S. solfataricus recombinase can utilize Mn2+ to stimulate strand invasion and reduce ADP-binding stability. Additionally, reduction of SsoRadA ATPase activity by Walker Box mutation or cofactor alteration resulted in a loss of large, complete strand exchange products. Depletion of ADP was found to improve initial strand invasion but also led to a similar loss of large strand exchange events. Our results indicate that overall, SsoRadA is distinct in its use of divalent cofactors but its activity with Mn2+ shows similarity to human RAD51 protein with Ca2+.

Elucidating the mechanism of Danicamtiv on force, kinetics, and myosin structure and function.

Myosin modulators are a novel class of small molecules that alter cardiac contractility. Omecamtiv mecarbil, the first identified myosin activator, showed only modest clinical benefits in systolic heart failure patients. Thus, there is an urgency to develop alternative myosin activators. Danicamtiv (Dani) has emerged as a potential candidate; however, a detailed mechanism is not known. Here, we aim to elucidate the mechanism of Dani on contractile function in pig cardiac muscle. Demembranated ventricular tissues show a significant 0.1 pCa unit increase in calcium sensitivity and 10% increase in maximal force after incubation in 1 µM Dani. The most potent effects occur in submaximal calcium concentrations, leading to a flattening of the force-calcium relationship, suggesting decreased cooperativity. Maximal rates of tension redevelopment are decreased by approximately 60% with Dani. Isolated cardiac myofibrils provide details about contractile kinetics. Experiments with 1 µM Dani show a 49% decrease in fast-phase relaxation kinetics. Slow-phase isometric relaxation exhibits 47% slower crossbridge detachment rate and 34% longer thin filament deactivation. Next, we assess ATP utilization in the crossbridge cycle. Filament sliding velocity slows 55% on addition of 0.5 µM Dani, similar to the effect of ADP on velocity. The effects of Dani and ADP are not additive suggesting a similar mode of action. ATP binding is unaltered up to 10 µM Dani using stopped flow spectroscopy. Results of X-ray diffraction studies of porcine myocardium at rest show an increase in equatorial intensity ratio (I1,1/I1,0) in response to 50 µM Dani, reflecting an increased proximity of myosin heads to the thin filament. In conclusion, we hypothesize that Dani primes the thick filament for activation and alters relaxation through inhibited ATP hydrolysis product release. Future studies will test these hypotheses.

Putative metabolism of Ca. Accumulibacter via the utilization of glucose

Ca. Accumulibacter was the predominant microorganism (relative FISH bio-abundance of 67 ± 5%) in a lab-scale sequential batch reactor that accomplished enhanced biological phosphorus removal (EBPR) while using glucose and acetate as the carbon sources (1:1 COD-based ratio). Both organic compounds were completely anaerobically consumed. The reactor's performance in terms of P/C ratio, phosphorous release and uptake, and overall kinetic and stoichiometric parameters were on the high end of the reported spectrum for EBPR systems (100:9.3 net mg phosphate removal per mg COD consumed when using glucose and acetate in a 1:1 ratio). The batch tests showed that, to the best of our knowledge, this is the first time a reactor enriched with Ca. Accumulibacter can putatively utilize glucose as the sole carbon source to biologically remove phosphate (COD:P (mg/mg) removal ratio of 100:6.3 when using only glucose). Thus, this research proposes that Ca. Accumulibacter directly anaerobically stored the fed glucose primarily as glycogen by utilizing the ATP provided via the hydrolysis of poly-P and secondarily as PHA by balancing its ATP utilization (glycogen generation) and formation (PHA storage). Alternative hypotheses are also discussed. The reported findings could challenge the conventional theories of glucose assimilation by Ca. Accumulibacter, and can be of significance for the biological removal of phosphorus from wastewaters with high contents of fermentable compounds or low VFAs.

Gene Editing and Multi-Omics Reveal Novel Metabolic Vulnerabilities in t(4;14)-Associated Multiple Myeloma

Background: Chromosomal translocation t(4;14) is a recurrent genetic lesion in multiple myeloma (MM) which drives aberrant overexpression of the histone methyltransferase NSD2 and is associated with a more guarded prognosis. Despite its oncogenic outcomes, NSD2 overexpression in MM cells could simultaneously confer cellular vulnerabilities that can be therapeutically exploited. Aim: To define potential therapeutic susceptibilities driven by NSD2 overexpression in t(4;14) MM. Methods: We performed genome-wide knockout screening in isogenic NSD2 high and low KMS11 cells using the Brunello CRISPR library, followed by validation of key target genes in several different t(4;14) MM cell lines. Results: These screens revealed increased reliance of NSD2-overexpressing cells on multiple cellular processes including mitochondrial respiration, transcriptional elongation and proteasomal degradation. One of the top preferential dependencies in NSD2-high MM cells is the mitochondrial adenine nucleotide regulator adenylate kinase 2 (AK2). AK2 catalyzes the reversible interconversion of ADP to ATP and AMP. Cancer Dependency Map (depmap) analysis indicated that AK2 loss is detrimental to most MM cell lines but it is not a dependency in most solid tumor cells. Reliance on AK2 was modest in t(4;14) MM cells engineered to express low levels of NSD2 but the detrimental effect of AK2 depletion by shRNA or CRISPR was exacerbated upon enforced overexpression of NSD2. Gene expression studies showed that AK2 suppression leads to induction of genes involved in oxidative stress response. Metabolomic profiling of NSD2 high and low isogenic MM cells demonstrated striking reduction of NAD+ and elevation of nicotinamide (NAM) levels in NSD2 overexpressing cells, which correlates with a 10-fold induction of expression of the NAD+ consuming enzyme CD38 by NSD2. NAD+ and its metabolite NADP+ are essential co-factors of multiple antioxidant enzymes and its depletion can exacerbate oxidative damage. Therefore, NAD+ depletion likely accounts for the increased susceptibility of NSD2 high MM cells to AK2 loss. In vitro cell proliferation/viability assays demonstrated increased sensitivity of NSD2 high MM cells to PI exposure suggesting that NSD2 overexpression drives a higher load of unfolded proteins, correlating with loss of NAD+ and redox system activity. AK2 suppression in MM cells also impairs activation of the adaptive unfolded protein response through the IRE1a-XBP1 axis leading to decreased protein folding capacity. The combination of high unfolded protein load and poor ATP shuttling to the endoplasmic reticulum (ER) secondary to AK2 loss may represent an additional mechanism of selective lethality. Furthermore, AK2 deficient MM cells displayed increased sensitivity to PIs. Transcriptomic analyses in NSD2 high and low MM cells revealed that NSD2 overexpression, besides driving an oncogenic transcriptional program, alters the expression of several genes involved in nucleotide metabolism. Perturbed nucleotide metabolism was further documented by untargeted metabolite profiling which showed a notable depletion of several pyrimidine metabolites when NSD2 is overexpressed. Intriguingly, induced reduction of pyrimidine synthesis by treatment with DHODH inhibitors appeared to be more detrimental in NSD2 overexpressing MM cells. Conclusions: NSD2 overexpression in MM cells alters cellular metabolism and confers higher susceptibility to oxidative stress and unfolded protein loads. By inducing the expression of NAD+ consuming enzymes, NSD2 overexpression results in NAD+ depletion which likely underlies the described vulnerabilities. Loss of the mitochondrial adenine nucleotide regulator AK2 is more detrimental to NSD2 overexpressing MM cells as it diminishes efficient ATP utilization in the ER perturbing the ability of MM cells to handle high loads of unfolded immunoglobulins and mitigate oxidative stress. Furthermore, integrated analyses of the different omics datasets highlighted other NSD2-driven liabilities, including mitochondrial respiration, transcriptional elongation and nucleotide metabolism, that can be targeted to improve prognosis of MM.

Mechanisms and Drug Intervention for Doxorubicin-Induced Cardiotoxicity Based on Mitochondrial Bioenergetics.

Doxorubicin (DOX) is an anthracycline chemotherapy drug, which is indispensable in antitumor therapy. However, its subsequent induction of cardiovascular disease (CVD) has become the primary cause of mortality in cancer survivors. Accumulating evidence has demonstrated that cardiac mitochondrial bioenergetics changes have become a significant marker for doxorubicin-induced cardiotoxicity (DIC). Here, we mainly summarize the related mechanisms of DOX-induced cardiac mitochondrial bioenergetics disorders reported in recent years, including mitochondrial substrate metabolism, the mitochondrial respiratory chain, myocardial ATP storage and utilization, and other mechanisms affecting mitochondrial bioenergetics. In addition, intervention for DOX-induced cardiac mitochondrial bioenergetics disorders using chemical drugs and traditional herbal medicine is also summarized, which will provide a comprehensive process to study and develop more appropriate therapeutic strategies for DIC.

Near-infrared Spectroscopy Estimation Of Combined Muscle Oxidative Capacity And Oxygen Diffusion Capacity In Humans

PURPOSE: Muscle oxygen uptake (mV̇O2) depends on both O2 supply (convective and diffusive O2 delivery) and O2 demand (ATP utilization rate and mitochondrial function). The mV̇O2 recovery rate constant (k) measured by near-infrared spectroscopy (NIRS), in the presence of non-limiting O2 availability, is associated with muscle oxidative capacity in vivo. However, when O2 availability is limiting, k may be limited by muscle O2 diffusing capacity (DmO2). We aimed to determine associations of: i) k obtained in different O2 availability conditions with ex vivo mitochondrial function and ii) the difference in k (∆k) between conditions of non-limiting and limiting O2 availability with capillary-to-fiber ratio (C:F). METHODS: 12 healthy participants volunteered (28 ± 5 yrs; V̇O2peak 37.1 ± 8.0 ml*kg-1*min-1). On visits 1 and 2, k of the vastus lateralis (VL) was measured by NIRS during 10-15 intermittent arterial occlusions performed immediately after moderate intensity constant work-rate exercise. The duration and timing of occlusions were manipulated to maintain TSI in a 10% range change either below (LOW) or above (HIGH) the mid-point of the functional range from a prolonged occlusion. ∆k is the difference between LOW and HIGH k measurements. On visit 3, the VL was biopsied to measure C:F and maximal O2 flux using saturating substrates for complexes I + II by high-resolution respirometry (HRR). RESULTS: O2 flux was 37.7 ± 10.6 and 56.8 ± 19.8 pmol*s-1*mg-1 wet weight in maximal ADP-stimulated phosphorylating state and maximal noncoupled state, respectively. C:F ratio ranged 2.15 to 2.49. k was greater in HIGH (3.15 ± 0.45 min-1) than in LOW (1.56 ± 0.79 min-1, p < 0.0001). k was significantly correlated with both HRR measurements in HIGH (r = 0.72 - 0.69), but not in LOW (r = -0.24 - -0.28). ∆k ranged -0.19 to -3.19 min-1, and was inversely correlated with C:F ratio (r = -0.68, p = 0.01). CONCLUSION: These data show that mV̇O2 recovery rate constant (k) reflected muscle oxidative capacity only under conditions of non-limiting O2 availability. Moreover, ∆k, obtained under different O2 availability conditions, was associated with C:F ratio, a mediator of DmO2. Thus, assessment of muscle k and ∆k using NIRS under HIGH and LOW TSI conditions provides a non-invasive window on both muscle oxidative capacity and muscle O2 diffusive capacity.

Specific ATPases drive compartmentalized glycogen utilization in rat skeletal muscle.

Glycogen is a key energy substrate in excitable tissue, including in skeletal muscle fibers where it also contributes to local energy production. Transmission electron microscopy imaging has revealed the existence of a heterogenic subcellular distribution of three distinct glycogen pools in skeletal muscle, which are thought to reflect the requirements for local energy stores at the subcellular level. Here, we show that the three main energy-consuming ATPases in skeletal muscles (Ca2+, Na+,K+, and myosin ATPases) utilize different local pools of glycogen. These results clearly demonstrate compartmentalized glycogen metabolism and emphasize that spatially distinct pools of glycogen particles act as energy substrate for separated energy requiring processes, suggesting a new model for understanding glycogen metabolism in working muscles, muscle fatigue, and metabolic disorders. These observations suggest that the distinct glycogen pools can regulate the functional state of mammalian muscle cells and have important implications for the understanding of how the balance between ATP utilization and ATP production is regulated at the cellular level in general and in skeletal muscle fibers in particular.

Unplanned Thirty-Day Readmission after Surgical Myectomy for Hypertrophic Obstructive Cardiomyopathy: Using the Nationwide Readmission Database

Hypertrophic Obstructive Cardiomyopathy (HOCM) often masquerades as coronary artery disease. Symptoms which persisted after a 30-day readmission following surgical myectomy included; angina-like chest pain owing to myocardial ischemia, shortness of breath/dyspnea, atrial fibrillation and diastolic dysfunction. HOCM is the most common inherited cardiac disorder. Our study honed-in on the predictability of readmission’s surging healthcare resources; for example, the cost and length of stay utilization after surgical myectomy. Recent theories about the cause of hypertrophy in HOCM patients have been linked to inefficient utilization of ATP. The purpose of this study is to access the incidence, predictors, as well as the causes for readmission in HOCM patients who undergo surgical myectomy. We wanted to investigate the incidence so as to better predict the causes for symptoms after a thirty-day readmission rate following surgical myectomy. Readmission nationwide rates from January 2010 to September 2015’s database was investigated to find out about the 30-day unplanned readmission after surgical myectomy. International Classification of Disease; ninth Revision, and Clinical Modification were used. Patients who were readmitted consisted of those with similar ages as well as sex as well as burdened with higher comorbidities

Comparative transcriptomic analysis unveils a network of energy reallocation in Litopenaeus vannamei responsive to heat-stress

Temperature serves as an important environmental factor in ecosystems. Understanding the cooperation of various tissues of animals in response to heat stress is the basis for clarifying the regulation mechanism of different species under heat stress. Herein, a comparative transcriptomic analysis was conducted on three tissues (hepatopancreas, gill and muscle) of the Pacific white shrimp Litopenaeus vannamei under heat stress. Three tissues displayed distinct gene expression patterns, suggesting a cooperation based on division of labor might have occurred among them. In hepatopancreas and gill, genes related to ATP generation and utilization were down-regulated, and energetically expensive protein turnover was almost shut down. While in muscle, genes related to ATP generation and utilization, and those involved in several energy-consuming processes were up-regulated. In consistent, significant accumulation of ATP and decrease of total protein concentration were detected in hepatopancreas and gill, while it was opposite in muscle. Therefore, we suggest that different tissues may cooperate with each other simultaneously via energy reallocation in response to heat stress. Less energy was channeled into protein turnover in gill and hepatopancreas, and more energy was required for muscle. This study not only provides a comprehensive understanding of the molecular mechanism of L. vannamei in response to high temperature, but also lays the foundation of mining thermotolerance genes and proposing effective strategies to cope with the high temperature environment.

Metabolic Reprogramming, Gut Dysbiosis, and Nutrition Intervention in Canine Heart Disease.

This review provides a state-of-the-art overview on recent advances in systems biology in canine cardiac disease, with a focus on our current understanding of bioenergetics and amino acid metabolism in myxomatous mitral valve disease (MMVD). Cross-species comparison is drawn to highlight the similarities between human and canine heart diseases. The adult mammalian heart exhibits a remarkable metabolic flexibility and shifts its energy substrate preference according to different physiological and pathological conditions. The failing heart suffers up to 40% ATP deficit and is compared to an engine running out of fuel. Bioenergetics and metabolic readaptations are among the major research topics in cardiac research today. Myocardial energy metabolism consists of three interconnected components: substrate utilization, oxidative phosphorylation, and ATP transport and utilization. Any disruption or uncoupling of these processes can result in deranged energy metabolism leading to heart failure (HF). The review describes the changes occurring in each of the three components of energy metabolism in MMVD and HF. It also provides an overview on the changes in circulating and myocardial glutathione, taurine, carnitines, branched-chain amino acid catabolism and tryptophan metabolic pathways. In addition, the review summarizes the potential role of the gut microbiome in MMVD and HF. As our knowledge and understanding in these molecular and metabolic processes increase, it becomes possible to use nutrition to address these changes and to slow the progression of the common heart diseases in dogs.

A mechanistic modeling framework reveals the key principles underlying tumor metabolism.

While aerobic glycolysis, or the Warburg effect, has for a long time been considered a hallmark of tumor metabolism, recent studies have revealed a far more complex picture. Tumor cells exhibit widespread metabolic heterogeneity, not only in their presentation of the Warburg effect but also in the nutrients and the metabolic pathways they are dependent on. Moreover, tumor cells can switch between different metabolic phenotypes in response to environmental cues and therapeutic interventions. A framework to analyze the observed metabolic heterogeneity and plasticity is, however, lacking. Using a mechanistic model that includes the key metabolic pathways active in tumor cells, we show that the inhibition of phosphofructokinase by excess ATP in the cytoplasm can drive a preference for aerobic glycolysis in fast-proliferating tumor cells. The differing rates of ATP utilization by tumor cells can therefore drive heterogeneity with respect to the presentation of the Warburg effect. Building upon this idea, we couple the metabolic phenotype of tumor cells to their migratory phenotype, and show that our model predictions are in agreement with previous experiments. Next, we report that the reliance of proliferating cells on different anaplerotic pathways depends on the relative availability of glucose and glutamine, and can further drive metabolic heterogeneity. Finally, using treatment of melanoma cells with a BRAF inhibitor as an example, we show that our model can be used to predict the metabolic and gene expression changes in cancer cells in response to drug treatment. By making predictions that are far more generalizable and interpretable as compared to previous tumor metabolism modeling approaches, our framework identifies key principles that govern tumor cell metabolism, and the reported heterogeneity and plasticity. These principles could be key to targeting the metabolic vulnerabilities of cancer.

Increased energy demand from anabolic-catabolic processes drives β-lactam antibiotic lethality

β-Lactam antibiotics disrupt the assembly of peptidoglycan (PG) within the bacterial cell wall by inhibiting the enzymatic activity of penicillin-binding proteins (PBPs). It was recently shown that β-lactam treatment initializes a futile cycle of PG synthesis and degradation, highlighting major gaps in our understanding of the lethal effects of PBP inhibition by β-lactam antibiotics. Here, we assess the downstream metabolic consequences of treatment of Escherichia coli with the β-lactam mecillinam and show that lethality from PBP2 inhibition is a specific consequence of toxic metabolic shifts induced by energy demand from multiple catabolic and anabolic processes, including accelerated protein synthesis downstream of PG futile cycling. Resource allocation into these processes is coincident with alterations in ATP synthesis and utilization, as well as a broadly dysregulated cellular redox environment. These results indicate that the disruption of normal anabolic-catabolic homeostasis by PBP inhibition is an essential factor for β-lactam antibiotic lethality.

788 Reverse McConnell’s sign in biventricular Takotsubo cardiomyopathy: how echo can guide the diagnosis

Abstract An 89-years-old woman presented at Emergency Department with a 10-h history of vertigo, headache, nausea, fatigue, and general discomfort. No chest pain or shortness of breath were reported. She had a history of hypertension, chronic kidney disease, paroxysmal atrial fibrillation (AF), osteoporosis, and hypoacusia. The patient suffered of chronic anxiety and the caregiver referred for a recent and acute emotional distress. At the admission, the patient didn’t show clinical signs of peripheral hypoperfusion. Fine crackles at lungs bases were objectivable with coherent ultra-sound lung comets and mild bilateral pleural effusion. Her usual therapy included nebivolol, apixaban, torsemide, candesartan, and D-vitamin. The EKG showed AF with a heart rate of about 110 b.p.m., no ST-segment deviation and normal QTc. The echo findings showed a slight increase in left ventricle volume with a severe reduction of the ejection fraction due to the akinesia of all apical segments with the typical aspect of the ‘apical ballooning’ and concomitant hyperkinesia of the basal segments. Despite normal dimensions, also the right ventricle showed a peculiar contractile pattern, with hyperkinetic basal movement and akinesia of the apex with the hinge point located in the free wall portion in continuity with the LV septal wall. No significant valvular disease was documented except for moderate tricuspid regurgitation. High-sensitive I troponin peaked up to 1500 pg/ml. The clinical appearance was very suggestive of TTS but INTERTAK score of 61 was not diagnostic and, according to the most recent consensus document, a coronary angiography was performed, without documentation of coronary artery disease. During the hospitalization serial electrocardiographic monitoring showed significant and transient QTc prolongation and dynamic T wave changes resulting in progressive INTERTAK score increase. No ventricular arrhythmic events occurred. The patient was treated with careful fluid support and with beta-blockers for AF rate control. Multiple echocardiographic evaluations documented a progressive recovery of systolic function up to complete normalization of biventricular global and regional systolic function. Clinical data, instrumental evidences and dynamic evolution oriented the diagnosis towards TTS with unusual and uneven impairment of right and left ventricular function. The described case focuses the attention on the reverse McConnell’s sign, an echocardiographic finding not often described in the literature, consisting of akinetic right ventricle apical segment and hyperkinetic basal and mid free wall. This discordant motion is exactly opposite to the classic echocardiographic RV aspect detected in acute significative pulmonary embolism described as McConnell’s sign, hence the name. It has been suggested that this functional variation might be a self-protection system of the heart through a mechanism of hibernation that is similar to that occurring during chronic hypoxia, consisting in a decrease in the ATP utilization and O2 consumption, as suggested by the activation of intracellular β2-induced signalling patterns documented in TTS. Recognizing this finding it’s important not only because it has been associated with a higher risk of developing haemodynamic instability but also to orient working diagnosis of TTS when initial clinical assessment through the INTERTAK score is inconclusive.