Glucose Breakdown Research Articles

Energy Dynamics in the Brain: Contributions of Astrocytes to Metabolism and pH Homeostasis.

Regulation of metabolism is complex and involves enzymes and membrane transporters, which form networks to support energy dynamics. Lactate, as a metabolic intermediate from glucose or glycogen breakdown, appears to play a major role as additional energetic substrate, which is shuttled between glycolytic and oxidative cells, both under hypoxic and normoxic conditions. Transport of lactate across the cell membrane is mediated by monocarboxylate transporters (MCTs) in cotransport with H+, which is a substrate, a signal and a modulator of metabolic processes. MCTs form a “transport metabolon” with carbonic anhydrases (CAs), which not only provide a rapid equilibrium between CO2, HCO3– and H+, but, in addition, enhances lactate transport, as found in Xenopus oocytes, employed as heterologous expression system, as well as in astrocytes and cancer cells. Functional interactions between different CA isoforms and MCTs have been found to be isoform-specific, independent of the enzyme’s catalytic activity, and they require physical interaction between the proteins. CAs mediate between different states of metabolic acidosis, induced by glycolysis and oxidative phosphorylation, and play a relay function in coupling pH regulation and metabolism. In the brain, metabolic processes in astrocytes appear to be linked to bicarbonate transport and to neuronal activity. Here, we focus on physiological processes of energy dynamics in astrocytes as well as on the transfer of energetic substrates to neurons.

Increased hexokinase interactions with mitochondria protect against cell damage

Deaths due to cancer and ischemic heart disease are the most common; dysfunction of mitochondrial energy (ATP) metabolism is key in these pathologies. Therefore, therapeutic strategies, which remain elusive, have focused on energetic metabolism. Cells use glucose and oxygen in glycolysis and oxidative phosphorylation to generate ATP. The cytosolic protein hexokinase (HK) plays a crucial role in glycolysis by catalyzing the breakdown of glucose to produce most of the ATP generated from mitochondria. For efficient glycolysis, HK must access the mitochondrial ATP, which flows out via the voltage dependent anion channel (VDAC), a 30‐kDa protein in the outer mitochondrial membrane (OMM). Cancer cells grow and proliferate by increasing access to ATP via increased HK‐VDAC associations. This strategy has potential implications for protection against cardiac ischemic injury. Ischemia promotes dissociation of HK from VDAC leading to cardiac damage, but cardio‐protective interventions can increase HK‐VDAC association, preserving function. The overall objective is to determine the biophysical and biochemical features that lead to HK‐VDAC association or dissociation. HK, a 100‐KDa dimeric protein, has 918 amino acids in two domains: an N‐terminus and C‐terminus joined by a linker a‐helix. HK interactions with mitochondria are not well known but, HK, with its non‐polar sequence of 15 amino acids on the N‐terminus, may insert in the OMM close to VDAC. Glucose and glucose‐6‐phospate have distinct binding sites on HK. Glucose binds at K173, D209, and E260 in the N‐terminus and at K621, D657, and E708 in the C‐terminus. The Brown Deer High School SMART Team designed a model of HK using 3‐D printing technology to investigate structure‐function relationships. Understanding HK‐VDAC binding mechanisms could provide better targeted approaches to manage pathologies, including cancer, cardiac and neurodegenerative diseases.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effect of liver fatty acid binding protein (L-FABP) gene ablation on lipid metabolism in high glucose diet (HGD) pair-fed mice

Liver fatty acid binding protein (L-FABP) is the major fatty acid binding/”chaperone” protein in hepatic cytosol. Although fatty acids can be derived from the breakdown of dietary fat and glucose, relatively little is known regarding the impact of L-FABP on phenotype in the context of high dietary glucose. Potential impact was examined in wild-type (WT) and Lfabp gene ablated (LKO) female mice fed either a control or pair-fed high glucose diet (HGD). WT mice fed HGD alone exhibited decreased whole body weight gain and weight gain/kcal food consumed—both as reduced lean tissue mass (LTM) and fat tissue mass (FTM). Conversely, LKO alone increased weight gain, lean tissue mass, and fat tissue mass while decreasing serum β-hydroxybutyrate (indicative of hepatic fatty acid oxidation)—regardless of diet. Both LKO alone and HGD alone significantly altered the serum lipoprotein profile and increased triacylglycerol (TG), but in HGD mice the LKO did not further exacerbate serum TG content. HGD had little effect on hepatic lipid composition in WT mice, but prevented the LKO-induced selective increase in hepatic phospholipid, free-cholesterol and cholesteryl-ester. Taken together, these findings suggest that high glucose diet diminished the effects of LKO on the whole body and lipid phenotype of these mice.

Metabolic alterations and the potential for targeting metabolic pathways in the treatment of multiple myeloma.

Metabolism is defined as the collection of complex biochemical processes that living cells use to generate energy and maintain their growth and survival. Metabolism encompasses the synthesis and breakdown of glucose, fatty acids, and amino acids; the generation of energy (ATP); and oxidative phosphorylation. In cancer cells, metabolism can be commandeered to promote tumor growth and cellular proliferation. These alterations in metabolism have emerged as an additional hallmark of various cancers. In this review we focus on metabolic alterations in multiple myeloma (MM) - a malignancy of plasma cells - including derangements in glycolysis, gluconeogenesis, the tricarboxylic acid cycle, oxidative phosphorylation, and fatty acid/amino acid synthesis and degradation. Particular focus is given to metabolic alterations that contribute to myeloma cell growth, proliferation and drug resistance. Finally, novel approaches that target metabolic pathways for the treatment of MM are discussed.

α-1 acid glycoprotein inhibits insulin responses by glucose oxidation, protein synthesis and protein breakdown in mouse C2C12 myotubes

Increased plasma α-1 acid glycoprotein (AGP) is correlated with reduced growth rates in neonatal swine. The specific physiological mechanisms contributing to this relationship are unknown. This study was performed to determine if AGP can modify muscle metabolism by examining glucose oxidation and protein synthesis in the C2C12 muscle cell line. Cells were used for experiments 4 days post-fusion as myotubes. Myotubes were exposed to AGP for 24 h, with the last 4 h used to monitor 14C-glucose oxidation or to measure protein synthesis by incorporation of 3H-tyrosine. Treatment of C2C12 myotubes with mouse AGP (100 µg/ml) reduced glucose oxidation (P<0.01, n=3 trials), whereas bovine insulin (1 µM) stimulated glucose oxidation (P<0.05, n=3 trials). Treatment with AGP in combination with insulin reduced 14C-glucose oxidation (P<0.05, n=3 trials), similar to the effect of AGP alone. Glucose transport, as measured by 3H-deoxyglucose uptake, was increased by 38% with 1 µM insulin (P<0.05, n=3 trials), whereas AGP alone increased glucose uptake by 36% (P<0.05, n=3 trials). The combination of insulin and AGP in the medium resulted in an 88% increase in glucose uptake (P<0.01, n=3 trials). Protein synthesis was measured by 3H-tyrosine incorporation into C2C12 myotubes. Insulin stimulated a 18% increase in 3H-tyrosine incorporation (P<0.05, n=6 trials). The incorporation of 3H-tyrosine into myotubes was reduced by 20% with AGP incubation (P<0.01, n=6 trials), like the 20% decrease in 3H-tyrosine incorporation in response to the combination of AGP and insulin (P<0.01, n=6 trials). Protein breakdown, as measured by the release of 3H-tyrosine from C2C12 myotubes, was reduced 27% by insulin (P<0.01, n=6 trials). Treatment with AGP had no effect on protein breakdown (P>0.05, n=6 trials), whereas incubation with both AGP and insulin reduced 3H-tyrosine release by 15% (P<0.01, n=6 trials). First, these data indicate that the acute phase protein AGP can interact with the skeletal muscle to reduce glucose oxidation, but this is not the result of an effect on glucose transport. Second, AGP can specifically reduce protein synthesis. Lastly, AGP can inhibit insulin-stimulated glucose oxidation, protein synthesis and breakdown.

Glycogen metabolism and glycogen storage disorders.

Glucose is the main energy fuel for the human brain. Maintenance of glucose homeostasis is therefore, crucial to meet cellular energy demands in both - normal physiological states and during stress or increased demands. Glucose is stored as glycogen primarily in the liver and skeletal muscle with a small amount stored in the brain. Liver glycogen primarily maintains blood glucose levels, while skeletal muscle glycogen is utilized during high-intensity exertion, and brain glycogen is an emergency cerebral energy source. Glycogen and glucose transform into one another through glycogen synthesis and degradation pathways. Thus, enzymatic defects along these pathways are associated with altered glucose metabolism and breakdown leading to hypoglycemia ± hepatomegaly and or liver disease in hepatic forms of glycogen storage disorder (GSD) and skeletal ± cardiac myopathy, depending on the site of the enzyme defects. Overall, defects in glycogen metabolism mainly present as GSDs and are a heterogenous group of inborn errors of carbohydrate metabolism. In this article we review the genetics, epidemiology, clinical and metabolic findings of various types of GSD, and glycolysis defects emphasizing current treatment and implications for future directions.

Glucose metabolism controls disease-specific signatures of macrophage effector functions.

In inflammatory blood vessel diseases, macrophages represent a key component of the vascular infiltrates and are responsible for tissue injury and wall remodeling. To examine whether inflammatory macrophages in the vessel wall display a single distinctive effector program, we compared functional profiles in patients with either coronary artery disease (CAD) or giant cell arteritis (GCA). Unexpectedly, monocyte-derived macrophages from the 2 patient cohorts displayed disease-specific signatures and differed fundamentally in metabolic fitness. Macrophages from CAD patients were high producers for T cell chemoattractants (CXCL9, CXCL10), the cytokines IL-1β and IL-6, and the immunoinhibitory ligand PD-L1. In contrast, macrophages from GCA patients upregulated production of T cell chemoattractants (CXCL9, CXCL10) but not IL-1β and IL-6, and were distinctly low for PD-L1 expression. Notably, disease-specific effector profiles were already identifiable in circulating monocytes. The chemokinehicytokinehiPD-L1hi signature in CAD macrophages was sustained by excess uptake and breakdown of glucose, placing metabolic control upstream of inflammatory function. We conclude that monocytes and macrophages contribute to vascular inflammation in a disease-specific and discernible pattern, have choices to commit to different functional trajectories, are dependent on glucose availability in their immediate microenvironment, and possess memory in their lineage commitment. Supported by the NIH (R01 AR042527, R01 HL117913, R01 AI108906, P01 HL129941, R01 AI108891, R01 AG045779 U19 AI057266, R01 AI129191), I01 BX001669, and the Cahill Discovery Fund.

Mitochondrial Glycolysis in a Major Lineage of Eukaryotes.

The establishment of the mitochondrion is seen as a transformational step in the origin of eukaryotes. With the mitochondrion came bioenergetic freedom to explore novel evolutionary space leading to the eukaryotic radiation known today. The tight integration of the bacterial endosymbiont with its archaeal host was accompanied by a massive endosymbiotic gene transfer resulting in a small mitochondrial genome which is just a ghost of the original incoming bacterial genome. This endosymbiotic gene transfer resulted in the loss of many genes, both from the bacterial symbiont as well the archaeal host. Loss of genes encoding redundant functions resulted in a replacement of the bulk of the host’s metabolism for those originating from the endosymbiont. Glycolysis is one such metabolic pathway in which the original archaeal enzymes have been replaced by bacterial enzymes from the endosymbiont. Glycolysis is a major catabolic pathway that provides cellular energy from the breakdown of glucose. The glycolytic pathway of eukaryotes appears to be bacterial in origin, and in well-studied model eukaryotes it takes place in the cytosol. In contrast, here we demonstrate that the latter stages of glycolysis take place in the mitochondria of stramenopiles, a diverse and ecologically important lineage of eukaryotes. Although our work is based on a limited sample of stramenopiles, it leaves open the possibility that the mitochondrial targeting of glycolytic enzymes in stramenopiles might represent the ancestral state for eukaryotes.

Glycogen metabolism and glycogen storage disorders

Glucose is the main energy fuel for the human brain. Maintenance of glucose homeostasis is therefore, crucial to meet cellular energy demands in both - normal physiological states and during stress or increased demands. Glucose is stored as glycogen primarily in the liver and skeletal muscle with a small amount stored in the brain. Liver glycogen primarily maintains blood glucose levels, while skeletal muscle glycogen is utilized during high-intensity exertion, and brain glycogen is an emergency cerebral energy source. Glycogen and glucose transform into one another through glycogen synthesis and degradation pathways. Thus, enzymatic defects along these pathways are associated with altered glucose metabolism and breakdown leading to hypoglycemia ± hepatomegaly and or liver disease in hepatic forms of glycogen storage disorder (GSD) and skeletal ± cardiac myopathy, depending on the site of the enzyme defects. Overall, defects in glycogen metabolism mainly present as GSDs and are a heterogenous group of inborn errors of carbohydrate metabolism. In this article we review the genetics, epidemiology, clinical and metabolic findings of various types of GSD, and glycolysis defects emphasizing current treatment and implications for future directions.

Evaluation of Cycloferin Supplement on Health Parameters in Experimentally Induced Diabetic Rats with and Without Exogenous Insulin

ABSTRACTCycloferin is an extract of the chemicals from the Cyclopia species, which grows only in small areas in the southwest and southeast of South Africa and has been consumed traditionally as a nourishing tea to treat numerous health issues and illnesses. Previous studies report that some of the active compounds in Cycloferin, such as pinitol (a modified sugar) and mangiferin (a glucoside), may reduce blood sugar levels and therefore may be used as a treatment for diabetes. Mangiferin, in particular, has been shown to stimulate carbohydrate oxidation and alleviate some effects of insulin resistance and hyperglycemia. Other active components of Cycloferin include flavones, isoflavones, coumestans, luteolin, 4-hydroxycinnamic acid, polyphenols, and xanthones. These active compounds are antioxidants, which can enhance glucose breakdown, lower blood lipids, and reduce the number of highly reactive compounds known as free radicals, which can alter cellular structure and function when present in large amounts. In this study, we explored the ameliorative effects of Cycloferin by treating streptozotocin- (STZ) injected rats with Cycloferin and evaluating its long-term and short-term effect on blood glucose levels and kidney and liver conditions of the diabetic-rendered rats. Our results demonstrated the ability of Cycloferin to both lower the blood glucose levels and reduce evidence of damage in kidney and liver in diabetic rats with and without exogenous insulin treatment for partial control of diabetic state.

Consequences of postnatal myo‐inositol supplementation on respiratory control and nucleus tractus solitarius (nTS) neurons

Myo‐inositol is a naturally occurring sugar derivative formed endogenously from the breakdown of glucose; it is also found in a variety of foods including breast milk and is commercially available as a nutritional supplement. Serum levels of myo‐inositol in infants decrease naturally over the first few postnatal weeks; prior studies in preterm infants have demonstrated improved pulmonary function, reduced incidence of respiratory distress, and increased survival rates following myo‐inositol supplementation. In support of a potential beneficial effect of myo‐inositol supplementation on respiratory control, we have shown previously that myo‐inositol treatment over the first 2 postnatal weeks enhances the acute hypoxic ventilatory response (HVR). In the present study, we tested the hypothesis that the enhanced HVR following myo‐inositol treatment would be associated with increased excitability of neurons within the area of brainstem chemoafferent integration, the nucleus tractus solitarius (nTS). Mouse pups received subcutaneous injections of myo‐inositol (80 mg/kg/day) for the first two postnatal weeks. Whole cell patch clamp recordings were then used to examine the excitatory properties of nTS neurons monosynaptically connected to the solitary tract. Compared to saline treated mice, myo‐inositol exposure increased the rheobase and the failure rate of nTS neurons, and decreased the paired pulse ratio following 20 Hz stimulation. Spontaneous activity (EPSC frequency, area, rise time, decay time), and basic neuronal properties (membrane resistance, capacitance, resting membrane potential) did not differ between groups. In conclusion, and contrary to our hypothesis, the enhanced HVR following postnatal myo‐inositol treatment was associated with decreased excitability of nTS neurons. We speculate the reduced nTS neuron excitability may be a compensatory response to increased chemoafferent (presumably the carotid body) inputs during hypoxia. These data may be important to our understanding of how myo‐inositol supplementation could influence development and function of brainstem respiratory neural control regions and may have implications for the pathophysiology of various respiratory morbidities in preterm infants.Support or Funding InformationThe Gerber FoundationThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Synbiotic Microencapsulation from Slow Digestible Colored Rice and Its Effect on Yoghurt Quality

Lactobacillus plantarum was encapsulated by slowly digestible hydrolyzed heat-moisture-treated (hydrolyzed-HMT) black waxy rice and applied in yoghurt. Incorporating these microcapsules in yoghurt resulted in higher viability of Lactobacillus bulgaricus C49 and Streptococcus thermophilus C44, especially in prolonged storage. The viability of L. bulgaricus and S. thermophilus (7.98 and 8.28 Log CFU/g) in synbiotic yoghurt was higher than in the control (7.81 and 7.96 Log CFU/g). Thirty-two aromatic compounds were detected and classified into 4 groups: alcohols, carbonyls, organic acids, and sulfur. Synbiotic yoghurt produced higher carbonyl compounds, particularly acetaldehyde and diacetyl. On the other hand, higher organic acid especially hexanoic, dodecanoic, acetic, butanoic, and pentanoic acids was observed at the end of fermentation but did not differ from control after storage. Ethanol was also higher in the synbiotic yoghurt due to the breakdown of glucose from starch and acetaldehyde by lactic acid bacteria. Weak correlation was found concerning sulfur compounds. Rice starch granules were aggregated and still retained its hexagonal shape, indicating high resistance to acid fermentation during 28 days of storage. The resistant starch coating from rice could provide a good prebiotic ingredient and allow the design of synbiotic yoghurt with enhanced aroma.

Myo-inositol Effects on the Developing Respiratory Neural Control System.

Myo-inositol is a highly abundant stereoisomer of the inositol family of sugar alcohols and forms the structural basis for a variety of polyphosphate derivatives including second messengers and membrane phospholipids. These derivatives regulate numerous cell processes including gene transcription, membrane excitability, vesicular trafficking, intracellular calcium signaling, and neuronal growth and development. Myo-inositol can be formed endogenously from the breakdown of glucose, is found in a variety of foods including breastmilk and is commercially available as a nutritional supplement. Abnormal myo-inositol metabolism has been shown to underlie the pathophysiology of a variety of clinical conditions including Down Syndrome, traumatic brain injury, bronchopulmonary dysplasia (BPD), and respiratory distress syndrome (RDS). Several animal studies have shown that myo-inositol may play a critical role in development of both the central and peripheral respiratory neural control system; a notable example is the neonatal apnea and respiratory insufficiency that manifests in a mouse model of myo-inositol depletion, an effect that is also postnatally lethal. This review focuses on myo-inositol (and some of its derivatives) and how it may play a role in respiratory neural control; we also discuss clinical evidence demonstrating a link between serum myo-inositol levels and the incidence of intermittent hypoxemia (IH) events (a surrogate measure of apnea of prematurity (AOP)) in preterm infants. Further, there are both animal and human infant studies that have demonstrated respiratory benefits following supplementation with myo-inositol, which highlights the prospects that nutritional requirements are important for appropriate development and maturation of the respiratory system.

The immunoinhibitory PD-1/PD-L1 pathway in inflammatory blood vessel disease.

Because of their vital function, the wall structures of medium and large arteries are immunoprivileged and protected from inflammatory attack. That vascular immunoprivilege is broken in atherosclerosis and in vasculitis, when wall-invading T cells and macrophages (Mϕ) promote tissue injury and maladaptive repair. Historically, tissue-residing T cells were studied for their antigen specificity, but recent progress has refocused attention to antigen-nonspecific regulation, which determines tissue access, persistence, and functional differentiation of T cells. The coinhibitory receptor PD-1, expressed on T cells, delivers negative signals when engaged by its ligand PD-L1, expressed on dendritic cells, Mϕ, and endothelial cells to attenuate T cell activation, effector functions, and survival. Through mitigating signals, the PD-1 immune checkpoint maintains tissue tolerance. In line with this concept, dendritic cells and Mϕs from patients with the vasculitic syndrome giant cell arteritis (GCA) are PD-L1lo ; including vessel-wall-embedded DCs that guard the vascular immunoprivilege. GCA infiltrates in the arterial walls are filled with PD-1+ T cells that secrete IFN-γ, IL-17, and IL-21; drive inflammation-associated angiogenesis; and facilitate intimal hyperplasia. Conversely, chronic tissue inflammation in the atherosclerotic plaque is associated with an overreactive PD-1 checkpoint. Plaque-residing Mϕs are PD-L1hi , a defect induced by their addiction to glucose and glycolytic breakdown. PD-L1hi Mϕs render patients with coronary artery disease immunocompromised and suppress antiviral immunity, including protective anti-varicella zoster virus T cells. Thus, immunoinhibitory signals affect several domains of vascular inflammation; failing PD-L1 in vasculitis enables unopposed immunostimulation and opens the flood gates for polyfunctional inflammatory T cells, and excess PD-L1 in the atherosclerotic plaque disables tissue-protective T cell immunity.

The gluconate shunt is an alternative route for directing glucose into the pentose phosphate pathway in fission yeast

Glycolysis and the pentose phosphate pathway both play a central role in the degradation of glucose in all domains of life. Another metabolic route that can facilitate glucose breakdown is the gluconate shunt. In this shunt glucose dehydrogenase and gluconate kinase catalyze the two-step conversion of glucose into the pentose phosphate pathway intermediate 6-phosphogluconate. Despite the presence of these enzymes in many organisms, their only established role is in the production of 6-phosphogluconate for the Entner-Doudoroff pathway. In this report we performed metabolic profiling on a strain of Schizosaccharomyces pombe lacking the zinc-responsive transcriptional repressor Loz1 with the goal of identifying metabolic pathways that were altered by cellular zinc status. This profiling revealed that loz1Δ cells accumulate higher levels of gluconate. We show that the altered gluconate levels in loz1Δ cells result from increased expression of gcd1 By analyzing the activity of recombinant Gcd1 in vitro and by measuring gluconate levels in strains lacking enzymes of the gluconate shunt we demonstrate that Gcd1 encodes a novel NADP+-dependent glucose dehydrogenase that acts in a pathway with the Idn1 gluconate kinase. We also find that cells lacking gcd1 and zwf1, which encode the first enzyme in the pentose phosphate pathway, have a more severe growth phenotype than cells lacking zwf1 We propose that in S. pombe Gcd1 and Idn1 act together to shunt glucose into the pentose phosphate pathway, creating an alternative route for directing glucose into the pentose phosphate pathway that bypasses hexokinase and the rate-limiting enzyme glucose-6-phosphate dehydrogenase.

The Potential Cardiovascular Benefits of Low-Glucose Degradation Product, Biocompatible Peritoneal Dialysis Fluids: A Review of the Literature.

Cardiovascular mortality in the end-stage renal disease (ESRD) population remains the leading cause of death. Targeting traditional cardiovascular risk factors has proven unsuccessful in this patient population, and therefore attention has turned to risk factors related to chronic kidney disease (CKD). The toxicity of high-glucose peritoneal dialysis (PD) solutions has been well documented. The breakdown of glucose into glucose degradation products (GDP) and advanced glycation end-products (AGE) has the ability to alter cell viability and cause premature apoptosis and is strongly correlated with interstitial fibrosis and microvascular sclerosis. Biocompatible solutions have been introduced to combat the hostile milieu to which PD patients are exposed.Given the considerable cardiovascular burden for PD patients, little is known about the cardiovascular impact the new biocompatible solutions may have. This review analyzes the existing literature regarding the mechanisms through which low-GDP solutions may modulate cardiovascular risk. Interventions using low-GDP solutions have provided encouraging changes in structural cardiovascular measures such as left ventricular mass (LVM), although metabolic changes from reduced GDP and AGE exposure yield inconclusive results on vascular remodelling. It is thought that the local effects of reduced glucose exposure may improve membrane integrity and therefore fluid status. Further research in the form of a robust randomized controlled trial should be carried out to assess the true extent of the cardiovascular benefits these biocompatible solutions may hold.

Thiamine Prescribing Practices for Adult Patients Admitted to an Internal Medicine Service.

Thiamine (vitamin B1) is an essential cofactor responsible for the breakdown of glucose, and its deficiency is associated with Wernicke encephalopathy (WE). There is a lack of evidence from systematic studies on the optimal dosing of thiamine for WE. Objectives: The primary objective was to describe the prescribing patterns for IV thiamine in adult patients admitted to a large teaching hospital. The secondary objective was to evaluate the clinical resolution of WE symptoms (confusion, ataxia, and/or ocular motor abnormalities) in relation to the dose of IV thiamine prescribed. A retrospective design was used to review data for adult patients admitted to an internal medicine service from June 1, 2014, to June 30, 2015. All patients included in the study received IV thiamine: low-dose therapy was defined as 100 mg IV daily and high-dose therapy was defined as dosage greater than 100 mg IV daily. A total of 141 patients were included; low-dose thiamine was prescribed for 115 (81.6%) and high-dose thiamine for 26 (18.4%). Patients for whom high-dose thiamine was prescribed were more likely to be those in whom a diagnosis of WE was being considered (12/26 [46.2%] versus 5/115 [4.3%], p < 0.001). Of the total 219 IV thiamine doses ordered, 180 (82.2%) were for 100 mg, and 143 (65.3%) were prescribed for once-daily administration. There was no statistically significant difference in the time to resolution of WE symptoms for patients receiving high-dose versus low-dose thiamine. A wide variety of thiamine prescribing patterns were noted. This study did not show a difference in time to resolution of WE symptoms in relation to the dose of IV thiamine. Additional large-scale studies are required to determine the optimal dosing of thiamine for WE.

A synthetic biochemistry platform for cell free production of monoterpenes from glucose

Cell-free systems designed to perform complex chemical conversions of biomass to biofuels or commodity chemicals are emerging as promising alternatives to the metabolic engineering of living cells. Here we design a system comprises 27 enzymes for the conversion of glucose into monoterpenes that generates both NAD(P)H and ATP in a modified glucose breakdown module and utilizes both cofactors for building terpenes. Different monoterpenes are produced in our system by changing the terpene synthase enzyme. The system is stable for the production of limonene, pinene and sabinene, and can operate continuously for at least 5 days from a single addition of glucose. We obtain conversion yields >95% and titres >15 g l−1. The titres are an order of magnitude over cellular toxicity limits and thus difficult to achieve using cell-based systems. Overall, these results highlight the potential of synthetic biochemistry approaches for producing bio-based chemicals.

Technical and clinical validation of the Greiner FC-Mix glycaemia tube.

Measurement of adequate glucose concentrations is complicated by in vitro breakdown of glucose due to glycolysis. Unlike the commonly used NaF-EDTA and NaF-oxalate phlebotomy tubes, citrated NaF-EDTA tubes are reported to directly and thereby completely inhibit glycolysis. Recently, Greiner introduced the Vacuette® FC-Mix NaF-EDTA-citrate tube, currently the only NaF-citrate tube without volume-disturbing liquid additions available on the European market. Here we present its potential as alternative for the laborious and therefore unfeasible conditions for glucose sampling as recommended by the World Health Organization (WHO). The FC-Mix tube was tested against the WHO recommended method of optimal laboratory conditions, both in healthy volunteers and pregnant woman undergoing oral glucose tolerance test (oGTT) for screening of gestational diabetes mellitus (GDM). Glucose concentrations were measured after different incubation times (0-48 h) and temperatures (room temperature, 37 °C), both in uncentrifuged whole blood and centrifuged material. Deming regression analysis shows that glucose concentrations measured in the FC-Mix tube correlate to the WHO recommended method. Stability is maintained at room temperature for 48 h and at least 24 h at 37 °C. The use of the FC-Mix tube was also validated in screening for GDM and proved comparable to the WHO recommended method in diagnostic outcome. The new Greiner FC-Mix tube combines the easy handling of a routine tube with dry additive with the ability to immediately inhibit glycolysis as in the WHO method for optimal pre-analytical and analytical conditions and performs equally to those conditions when screening for GDM.

Oncometabolic Tracks in the Heart.

The term cancer and the heart is readily associated with the cardiotoxicity of antineoplastic agents, such as anthracyclines or receptor tyrosine kinase inhibitors. This Viewpoint offers a different perspective, drawing attention to the consequences of metabolic dysregulation in cancers for energy substrate metabolism and contractile function of the heart and to common cellular strategies present in cancers and in the failing heart. On the basis of his observations in proliferating ascites tumor cells, Otto Warburg1 proposed that cancer cells derive their energy from the glycolytic breakdown of glucose even in oxygen-rich conditions. Warburg postulated that this metabolic shift, or oncometabolism, arose from dysfunctional mitochondria, and the inability of cancer cells to carry out oxidative phosphorylation. The term oncometabolism refers to an ensemble of metabolic rearrangements that accompany oncogenesis and tumor progression. Recent advances in cancer cell metabolism research have amended Warburg’s seminal findings by showing, for example, that mitochondrial metabolism in cancer cells is not defective. Today’s system-oriented view is that the metabolism of cancer cells is reprogrammed to optimize the flux of glucose and amino acids into biosynthetic pathways supporting proliferation and cell division.2,3 In the context of cancer, metabolic rearrangements are required to enable tumor growth. Similar to cancer cells, cardiac metabolism is remodeled in response to stress, which allows fluxes of intermediary substrates to meet the challenges of energy demand and macromolecule synthesis. There are several lines of evidence for this hypothesis. First, the failing human heart reverts to the metabolic gene program of the fetal heart,4 which causes a shift from predominately utilization of fatty acids to glucose. Second, when stressed by pressure overload, the heart responds with an increase in glucose metabolism, as shown both ex vivo and in vivo.5 In other words, the metabolic remodeling …