Glucose Consumption Rate Research Articles

Metformin enhances antitumor action ofsodiumdichloroacetate against glioma C6.

To investigate the anti-glioma activity of sodium dichloroacetate (DCA) and metformin (MTF) used in combination in vitro and in vivo. Cell survival, cell cycle, apoptosis, mitochondrial membrane potential (Δψm), ATP level, the glucose consumption rate, and lactate production rate were determined in vitro in cultured glioma C6cells. The antitumor action of agents in vivo was evaluated routinely by the prolongation of the life span of rats with transplanted intracerebral glioma C6and was confirmed by histological examination of tumor tissue. The half maximal inhibitory concentration (IC50) for DCA and MTF used separately was 79.2±2.1mM and 78.4±4.0mM, respectively, whereas IC50for DCA used in combination with 7.8mM MTF was 3.3fold lower (24.0±1.2mM, p < 0.05). The 1-day incubation of cells with DCA at a concentration close to IC50 (25mM), in combination with MTF at a concentration by order lower than IC50 (7.8mM), in contrast to their separate use, resulted in a decrease in the number of viable cells by 40% (p < 0.05); redistribution of the cells by the cell cycle phases toward decreased proportion of cells in the S-phase by 46% (p < 0.05) and an increased percentage of cells in the G0/G1phase by 24% (p < 0.05) compared to similar indices in the control. High proapoptotic activity of DCA in combination with MTF was supported by a significantly higher percentage of apoptotic cells in vitro than in the control (18.9±4.4% vs 5.7±1.3%, p < 0.05) and a high number of tumor cells with signs of apoptosis revealed during the histological examination of tumor pathomorphosis. The combined effect of DCA and MTF resulted in almost 4-fold decrease of the glucose consumption rate by glioma C6cells (0.23±0.05μmol/106cells/h vs 0.91 ± 0.12μmol/106cells/h, p < 0.05) compared to the corresponding parameters in the control, and 2-fold increased rate of lactate production (1.06 ± 0.03μmol/106cells/h vs 0.53 ± 0.03μmol/106cells/h, p < 0.05). At the same time, both Δψm and the level of intracellular ATP in the glioma C6cells treated with DCA and MTF, both separately and in combination, did not differ significantly from those indices in the control. In in vivo studies, the average life span of rats with intracranial transplanted glioma C6, treated with DCA in combination with MTF in a total dose of 1.1and 2.6g/kg body weight, respectively, was 50% higher (p < 0.001) than in the control group. In contrast, in the case of single-use (at a dose of 2.6g/kg), MTF increased the life span of tumor-bearing animals just by 19% (p < 0.01), whereas DCA alone (at a dose of 1.1g/kg) did not significantly change the survival time of rats. The obtained data indicate synergism of anti-glioma action of DCA and MTF in a case of their combined use both in vitro and in vivo and may be considered a starting point for the development of effective treatment regimens for malignant brain tumors based on the combined use of DCA and MTF.

Effect on growth, sugar consumption, and aerobic ethanol fermentation of homologous expression of the sugar transporter gene Pshxt1 in the white rot fungus Phanerochaete sordida YK-624

Major facilitator superfamily (MFS) transporters are found in all organisms. Although numerous studies have examined the functions of yeast and mold MFS transporters in terms of sugar affinity and metabolic regulation, no functional analyses of MFS sugar transporters in white rot fungi have been reported. This study identified an MFS sugar transporter gene (Pshxt1) of the white rot fungus Phanerochaete sordida YK-624 expressed in liquid culture containing low concentrations of nitrogen source. Homologous expression of Pshxt1 dramatically increased the rates of glucose, fructose, mannose, and xylose consumption. Galactose consumption increased slightly but significantly. These data suggest that Pshxt1 has broad affinity for monosaccharides. In contrast, a transformant homologously expressing Pshxt1 consumed glucose in preference to xylose in wood enzymatic-digestion liquor and liquid culture. Additionally, homologous expression of Pshxt1 improved mycelial growth, aerobic ethanol production, and simultaneous aerobic saccharification and fermentation efficiency, whereas secretion of the ligninolytic enzyme manganese peroxidase was clearly decreased in the presence of glucose by Pshxt1 expression. These results suggest that Pshxt1 is involved in the repression of ligninolytic enzyme activity via carbon catabolite repression at sufficiently high glucose concentrations for activation of primary metabolism.

Investigating how biomass hydrolysis derivatives inhibit H2 production by an isolated Clostridium beijerinckii

This study evaluates how fermentation inhibitors derived from biomass, namely 5-hydroxymethylfurfural (HMF), levulinic acid (LA), and formic acid (FA), affect H2 production by a Clostridium beijerinckii strain. The specific fermentative H2 production rate (μH2), bacterial cell growth rate (μ), and substrate (glucose) consumption rate (μS) during fermentation helped to estimate which HMF, LA, and FA concentrations inhibited 50% of the rates (IC50). IC50 for μ was 2.4, 2.7, and 1.4 g/L for HMF, LA, and FA, respectively. HMF inhibited H2 production the most potently and favored the lactate and ethanol pathways. Butyric acid was the only metabolite to be detected in the presence of LA or FA, which attested that these inhibitors completely inhibited the acetate pathway. The glucose consumption rate was the least affected by the inhibitors, and FA was more potent than HMF and LA. This information should be useful for more appropriate biomass feedstock application in fermentative H2 production.

The Cytotoxic Properties of Baeckea frutescens Branches Extracts in Eliminating Breast Cancer Cells

Breast cancer is the leading cause of cancer death in women in over 100 countries worldwide and accounts for almost 1 in 4 cancer cases among women. Baeckea frutescens of the family Myrtaceae has been used in traditional medicine and is known to possess antibacterial, antipyretic, and cytoprotective properties. In this study, we investigated the role of Baeckea frutescens branches extracts against human breast cancer cells. Baeckea frutescens branches extracts were prepared using Soxhlet apparatus with solvents of different polarity. The selective cytotoxic activity and the glucose consumption rate of Baeckea frutescens branches extracts of various concentrations (20 to 160 ug/ml) at 24-, 48-, and 72-hour time points were studied using MTT and glucose uptake assay. The IC50 values in human breast cancer (MCF-7 and MDA-MB-231) and mammary breast (MCF10A) cell lines were determined. Apoptotic study using AO/PI double staining was performed using fluorescent microscopy. The glucose uptake was measured using 2-NBDG, a fluorescent glucose analogue. The phytochemical screening of major secondary metabolites in plants was performed. This study reports that Baeckea frutescens branches extracts showed potent selective cytotoxic activity against MCF-7 cells compared to MDA-MB-231 cells after 72 hours of treatment. Evidence of early apoptosis which includes membrane blebbing and chromatin condensation was observed after 72 hours of treatment with Baeckea frutescens branches extracts. Interestingly, for the glucose uptake assay, the inhibition was observed as early as 24 hours upon treatment. All Baeckea frutescens extracts showed the presence of major secondary metabolites such as tannin, triterpenoid, flavonoid, and phenol. However, alkaloid level was unable to be determined. The identification of Baeckea frutescens and its possible role in selectively inhibiting glucose consumption in breast cancer cells defines a new role of natural product that can be utilised as an effective agent that regulates metabolic reprogramming in breast cancer.

Valorization of organic waste with simultaneous biogas upgrading for the production of succinic acid

Increased awareness on environmental drawbacks of petroleum-based industries are promoting transition from fossil-based succinic acid to its bio-based alternative. However, due to low price of oil the economic feasibility of the bio-succinic acid production is still challenged. The current study focuses on valorization of organic fraction of household kitchen waste pretreated by enzymatic hydrolysis to produce succinic acid with process CO2 supply from biogas. The total sugar content of 119.3 ± 1.7 g/L with 15% xylose and 85% glucose was obtained by enzymatic hydrolysis. Moreover, based on substrate inhibition tests with glucose, lower glucose concentration was more efficient in terms of succinic acid yield and production rate. Through fermentation of hydrolysate (17 g/L sugar) with Basfia succiniciproducens succinic acid was produced in 0.46 ± 0.0 and 0.25 ± 0.0 gSA/gglucose, using magnesium carbonate and raw biogas, respectively. Batch fermentation in the bioreactor with raw biogas resulted in glucose consumption rate of 2.22 ± 0.25 gGlu/gDCW.h, and 8.0% (v/v) of CO2 decrease compared to raw biogas. This study shows a proof of concept of organic waste valorization and raw biogas application in succinic acid production.

Effects of Oxygen Concentration and Culture Time on Porcine Nucleus Pulposus Cell Metabolism: An in vitro Study.

Low back pain is a common ailment that affects millions of individuals each year and is linked to degeneration of the intervertebral discs in the spine. Intervertebral disc degeneration is known to result from an imbalance in anabolic and catabolic activity by disc cells. Due to the avascular nature of the intervertebral disc, oxygen deficiency may occur in the central nucleus pulposus (NP). The resulting hypoxia affects matrix regulation and energy metabolism of disc cells, although the mechanisms are not fully understood. This study investigates in vitro glucose consumption and gene expression by NP cells over time under varying oxygen tensions. Notochordal porcine NP cells were cultured in agarose discs at 21, 5, or 1% oxygen tension for 1, 5, or 10 days. The expression of 10 key matrix genes, as well as Brachyury (T), by NP cells was analyzed using RT-PCR. Glucose consumption was measured using a two-point method. Results show that culture time and oxygen tension significantly affect glucose consumption rates by porcine NP cells. There were also significant changes in T expression based on oxygen level and culture time. The 1% oxygen tension had a significantly higher T expression on day 10 than the other two groups, which may indicate a better maintenance of the notochordal phenotype. MMP 1 and 13 expression increased over time for all groups, while only the 5% group showed an increase over time for MMP 3. TIMP expression followed the direction of MMPs but to a lesser magnitude. Five percent and twenty-one percent oxygen tensions led to decreases in anabolic gene expression while 1% led to increases. Oxygen concentration and culture time significantly impacted glucose consumption rate and the gene expression of matrix regulatory genes with hypoxic conditions most accurately maintaining the proper NP phenotype. This information is valuable not only for understanding disc pathophysiology, but also for harnessing the potential of notochordal NP cells in therapeutic applications.

B7-H3 promotes aerobic glycolysis and chemoresistance in colorectal cancer cells by regulating HK2

Accumulating evidence suggests that aerobic glycolysis is important for colorectal cancer (CRC) development. However, the underlying mechanisms have yet to be elucidated. B7-H3, an immunoregulatory protein, is broadly overexpressed by multiple tumor types and plays a vital role in tumor progression. In this study, we found that overexpression of B7-H3 effectively increased the rate of glucose consumption and lactate production, whereas knockdown of B7-H3 had the opposite effect. Furthermore, we showed that B7-H3 increased glucose consumption and lactate production by promoting hexokinase 2 (HK2) expression in CRC cells, and we also found that HK2 was a key mediator of B7-H3-induced CRC chemoresistance. Depletion of HK2 expression or treating cells with HK2 inhibitors could reverse the B7-H3-induced increase in aerobic glycolysis and B7-H3-endowed chemoresistance of cancer cells. Moreover, we verified a positive correlation between the expression of B7-H3 and HK2 in tumor tissues of CRC patients. Collectively, our findings suggest that B7-H3 may be a novel regulator of glucose metabolism and chemoresistance via controlling HK2 expression in CRC cells, a result that could help develop B7-H3 as a promising therapeutic target for CRC treatment.

Interobserver variability of image-derived arterial blood SUV in whole-body FDG PET

BackgroundToday, the standardized uptake value (SUV) is essentially the only means for quantitative evaluation of static [18F-]fluorodeoxyglucose (FDG) positron emission tomography (PET) investigations. However, the SUV approach has several well-known shortcomings which adversely affect the reliability of the SUV as a surrogate of the metabolic rate of glucose consumption. The standard uptake ratio (SUR), i.e., the uptake time-corrected ratio of tumor SUV to image-derived arterial blood SUV, has been shown in the first clinical studies to overcome most of these shortcomings, to decrease test-retest variability, and to increase the prognostic value in comparison to SUV. However, it is unclear, to what extent the SUR approach is vulnerable to observer variability of the additionally required blood SUV (BSUV) determination. The goal of the present work was the investigation of the interobserver variability of image-derived BSUV.MethodsFDG PET/CT scans from 83 patients (72 male, 11 female) with non-small cell lung cancer (N = 46) or head and neck cancer (N = 37) were included. BSUV was determined by 8 individuals, each applying a dedicated delineation tool for the BSUV determination in the aorta. Two of the observers applied two further tools. Altogether, five different delineation tools were used. With each used tool, delineation was performed for the whole patient group, resulting in 12 distinct observations per patient. Intersubject variability of BSUV determination was assessed using the fractional deviations for the individual patients from the patient group average and was quantified as standard deviation (SD is), 95% confidence interval, and range.Interobserver variability of BSUV determination was assessed using the fractional deviations of the individual observers from the observer-average for the considered patient and quantified as standard deviations (SD p, SD d) or root mean square (RMS), 95% confidence interval, and range in each patient, each observer, and the pooled data respectively.ResultsInterobserver variability in the pooled data amounts to RMS = 2.8% and is much smaller than the intersubject variability of BSUV (SD is= 16%). Averaged over the whole patient group, deviations of individual observers from the observer average are very small and fall in the range [ − 0.96, 1.05]%. However, interobserver variability partly differs distinctly for different patients, covering a range of [0.7, 7.4]% in the investigated patient group.ConclusionThe present investigation demonstrates that the image-based manual determination of BSUV in the aorta is sufficiently reproducible across different observers and delineation tools which is a prerequisite for accurate SUR determination. This finding is in line with the already demonstrated superior prognostic value of SUR in comparison to SUV in the first clinical studies.

Enhanced ethanol production from industrial lignocellulose hydrolysates by a hydrolysate-cofermenting Saccharomyces cerevisiae strain.

Industrial production of lignocellulosic ethanol requires a microorganism utilizing both hexose and pentose, and tolerating inhibitors. In this study, a hydrolysate-cofermenting Saccharomyces cerevisiae strain was obtained through one step in vivo DNA assembly of pentose-metabolizing pathway genes, followed by consecutive adaptive evolution in pentose media containing acetic acid, and direct screening in biomass hydrolysate media. The strain was able to coferment glucose and xylose in synthetic media with the respective maximal specific rates of glucose and xylose consumption, and ethanol production of 3.47, 0.38 and 1.62g/gDW/h, with an ethanol titre of 41.07g/L and yield of 0.42g/g. Industrial wheat straw hydrolysate fermentation resulted in maximal specific rates of glucose and xylose consumption, and ethanol production of 2.61, 0.54 and 1.38g/g DW/h, respectively, with an ethanol titre of 54.11g/L and yield of 0.44g/g. These are among the best for wheat straw hydrolysate fermentation through separate hydrolysis and cofermentation.

Growth-dependent recombinant product formation kinetics can be reproduced through engineering of glucose transport and is prone to phenotypic heterogeneity

BackgroundEscherichia coli W3110 and a group of six isogenic derivatives, each displaying distinct specific rates of glucose consumption were characterized to determine levels of GFP production and population heterogeneity. These strains have single or combinatory deletions in genes encoding phosphoenolpyruvate:sugar phosphotransferase system (PTS) permeases as PtsG and ManX, as well as common components EI, Hpr protein and EIIA, also the non-PTS Mgl galactose/glucose ABC transporter. They have been transformed for expressing GFP based on a lac-based expression vector, which is subject to bistability.ResultsThese strains displayed specific glucose consumption and growth rates ranging from 1.75 to 0.45 g/g h and 0.54 to 0.16 h−1, respectively. The rate of acetate production was strongly reduced in all mutant strains when compared with W3110/pV21. In bioreactor cultures, wild type W3110/pV21 produced 50.51 mg/L GFP, whereas strains WG/pV21 with inactive PTS IICBGlc and WGM/pV21 with the additional inactivation of PTS IIABMan showed the highest titers of GFP, corresponding to 342 and 438 mg/L, respectively. Moreover, we showed experimentally that bistable expression systems, as lac-based ones, induce strong phenotypic segregation among microbial populations.ConclusionsWe have demonstrated that reduction on glucose consumption rate in E. coli leads to an improvement of GFP production. Furthermore, from the perspective of phenotypic heterogeneity, we observed in this case that heterogeneous systems are also the ones leading to the highest performance. This observation suggests reconsidering the generally accepted proposition stating that phenotypic heterogeneity is generally unwanted in bioprocess applications.

Engineering of Corynebacterium glutamicum as a prototrophic pyruvate-producing strain: Characterization of a ramA-deficient mutant and its application for metabolic engineering.

To construct a prototrophic Corynebacterium glutamicum strain that efficiently produces pyruvate from glucose, the effects of inactivating RamA, a global regulator responsible for activating the oxidative tricarboxylic acid (TCA) cycle, on glucose metabolism were investigated. ΔramA showed an increased specific glucose consumption rate, decreased growth, comparable pyruvate production, higher formation of lactate and acetate, and lower accumulation of succinate and 2-oxoglutarate compared to the wild type. A significant decrease in pyruvate dehydrogenase complex activity was observed for ΔramA, indicating reduced carbon flow to the TCA cycle in ΔramA. To create an efficient pyruvate producer, the ramA gene was deleted in a strain lacking the genes involved in all known lactate- and acetate-producing pathways. The resulting mutant produced 161mM pyruvate from 222mM glucose, which was significantly higher than that of the parent (89.3mM; 1.80-fold).

Hyper-Osmotic Stress Elicits Membrane Depolarization and Decreased Permeability in Halotolerant Marine Debaryomyces hansenii Strains and in Saccharomyces cerevisiae.

The use of seawater and marine microorganisms can represent a sustainable alternative to avoid large consumption of freshwater performing industrial bioprocesses. Debaryomyces hansenii, which is a known halotolerant yeast, possess metabolic traits appealing for developing such processes. For this purpose, we studied salt stress exposure of two D. hansenii strains isolated from marine fauna. We found that the presence of sea salts during the cultivation results in a slight decrease of biomass yields. Nevertheless, higher concentration of NaCl (2 M) negatively affects other growth parameters, like growth rate and glucose consumption rate. To maintain an isosmotic condition, the cells accumulate glycerol as compatible solute. Flow cytometry analysis revealed that the osmotic adaptation causes a reduced cellular permeability to cell-permeant dye SYBR Green I. We demonstrate that this fast and reversible phenomenon is correlated to the induction of membrane depolarization, and occurred even in presence of high concentration of sorbitol. The decrease of membrane permeability induced by osmotic stress confers to D. hansenii resistance to cationic drugs like Hygromycin B. In addition, we describe that also in Saccharomyces cerevisiae the exposure to hyper-osmotic conditions induced membrane depolarization and reduced the membrane permeability. These aspects are very relevant for the optimization of industrial bioprocesses, as in the case of fermentations and bioconversions carried out by using media/buffers containing high nutrients/salts concentrations. Indeed, an efficient transport of molecules (nutrients, substrates, and products) is the prerequisite for an efficient cellular performance, and ultimately for the efficiency of the industrial process.

Three new phenylacetamide glycosides from Dracocephalum tanguticum Maxim and their anti-hyperglycemic activity

Three new phenylacetamide glycosides (1–3) together with one known phenylacetamide glycoside (4) and two known flavonoid glycosides (5–6) were isolated from whole plants of Dracocephalum tanguticum. The structure of all compounds were elucidated based on spectroscopic data analysis and comparison with data reported in related literature. Compounds (1–3) were evaluated for their anti-hyperglycemic and anti-fungal (Candida albicans) activities, the results revealed that all of them showed moderate activity with 3T3-L1 adipocytes glucose consumption rate of 20.80 ± 1.47%, 21.48 ± 2.44%, and 21.57 ± 1.35%, respectively at the final concentration of 25 μM. However, none of them showed obvious Candida albicans inhibitory activity.

AMPK Inhibition Suppresses the Malignant Phenotype of Pancreatic Cancer Cells in Part by Attenuating Aerobic Glycolysis.

Pancreatic cancer is a highly aggressive tumor characterized by enhanced aerobic glycolysis. AMP-activated protein kinase (AMPK), which is identified as a well-known regulator of glycolysis, plays an essential role in tumorigenesis. In the present study, we aim to explore the function of AMPK in pancreatic cancer cells and attempt to clarify the possible underlying mechanism. The Cancer Genome Atlas (TCGA) data showed that elevated AMPK expression highly correlated with lower median survival time. In an in vitro study, inhibition of AMPK blocked the proliferation, migration, and invasion ability of four cell lines under normoxia and hypoxia. Additionally, AMPK suppression led to cell cycle arrest and remarkably induced apoptosis. Furthermore, the lactic acid content, ATP content, and the glucose consumption rate were significantly reduced in all four cell lines under different conditions, accompanied by down-regulation of glycolytic biomarkers including phosphorylated mammalian target of rapamycin (p-mTOR)/total mTOR (t-mTOR), Pyruvate kinase M2 (Pkm2), and Hexokinase 2 (Hk2). Collectively, our data showed that AMPK activation is highly involved in pancreatic cancer progression and exerts its pro-tumorigenic functions partly by sustaining glycolytic activity. Hence, AMPK is expected to be a potential therapeutic target for pancreatic cancer.

Comparison of different quantification methods for 18F-fluorodeoxyglucose-positron emission tomography studies in rat brains

OBJECTIVES:This study aimed to evaluate several methods to estimate glucose consumption in the male Wister rat brain as measured by PET.METHODS:Fourteen male Wistar normoglycemic rats were studied. The input function consisted of seventeen blood samples drawn manually from the femoral artery. Glucose uptake values were calculated using the input function resulting from the arterial blood samples and the tissue time-activity curve derived from the PET images. The estimated glucose consumption rate (Ki) based on the 2-tissue compartment model (2TCM) served as the standard for comparisons with the values calculated by the Patlak analysis and with the fractional uptake rate (FUR), standardized uptake value (SUV) and glucose corrected SUV (SUVglu).RESULTS:No significant difference between the standard Ki and the Patlak Ki was observed. The standard Ki was also found to have strong correlations and concordance with the Ki value estimated by the Patlak analysis. The FUR method presented an excellent correlation with the Ki value obtained by the 2TCM/Patlak analyses, in contrast to the SUV or SUVglu.CONCLUSIONS:From a methodological point of view, the present findings confirm the theoretical limitations of the cerebral SUV and SUVglu as a substitute for Ki in the estimation of glucose consumption in the brain. Our data suggest that the FUR is the surrogate to Ki.

Spatial control of neuronal metabolism through glucose-mediated mitochondrial transport regulation.

Eukaryotic cells modulate their metabolism by organizing metabolic components in response to varying nutrient availability and energy demands. In rat axons, mitochondria respond to glucose levels by halting active transport in high glucose regions. We employ quantitative modeling to explore physical limits on spatial organization of mitochondria and localized metabolic enhancement through regulated stopping of processive motion. We delineate the role of key parameters, including cellular glucose uptake and consumption rates, that are expected to modulate mitochondrial distribution and metabolic response in spatially varying glucose conditions. Our estimates indicate that physiological brain glucose levels fall within the limited range necessary for metabolic enhancement. Hence mitochondrial localization is shown to be a plausible regulatory mechanism for neuronal metabolic flexibility in the presence of spatially heterogeneous glucose, as may occur in long processes of projection neurons. These findings provide a framework for the control of cellular bioenergetics through organelle trafficking.

Glucose biofuel cells using the two-step reduction reaction of bienzyme structure as cathodic catalyst

Glucose oxidase (GOx) and horseradish peroxidase (HRP) based bienzymes are entrapped in a polyethylenimine (PEI) matrix and then immobilized onto a substrate consisting of carbon nanotube (CNT) and pyrene boronic acid (PBA) (CNT/PBA/[HRP/PEI/GOx]). This structure is considered as the cathodic catalyst for the glucose biofuel cell (GBFC). According to the performance evaluations of the catalyst, the catalytic activity for the oxygen reduction reaction (ORR) is improved because of the bienzyme entrapped well in PEI, and also, because the CNT/PBA substrate promotes electron transfer by the formation of π–π stacking and the reduction of the electron transfer pathway distance. The high ORR reaction rate (38.7μAcm−2 in the injection of 5mM glucose) is clear evidence of an excellent catalyst. In addition, when the catalyst is adopted for the operation of a membrane GBFC, a high-power density (77.9±2.3μWcm−2) is achieved, as well as good storage stability (81% of its initial activity even after 4 weeks) and a high glucose consumption rate (8.7±0.2% from its initial concentration during 7 operating hours). Alternatively, when the catalyst is used for the membraneless GBFC operation, a relatively high-power density of 18μWcm−2 is also obtained.

In vivo X-Nuclear MRS Imaging Methods for Quantitative Assessment of Neuroenergetic Biomarkers in Studying Brain Function and Aging.

Brain relies on glucose and oxygen metabolisms to generate biochemical energy in the form of adenosine triphosphate (ATP) for supporting electrophysiological activities and neural signaling under resting or working state. Aging is associated with declined mitochondrial functionality and decreased cerebral energy metabolism, and thus, is a major risk factor in developing neurodegenerative diseases including Alzheimer’s disease (AD). However, there is an unmet need in the development of novel neuroimaging tools and sensitive biomarkers for detecting abnormal energy metabolism and impaired mitochondrial function, especially in an early stage of the neurodegenerative diseases. Recent advancements in developing multimodal high-field in vivo X-nuclear (e.g., 2H, 17O and 31P) MRS imaging techniques have shown promise for quantitative and noninvasive measurement of fundamental cerebral metabolic rates of glucose and oxygen consumption, ATP production as well as nicotinamide adenine dinucleotide (NAD) redox state in preclinical animal and human brains. These metabolic neuroimaging measurements could provide new insights and quantitative bioenergetic markers associated with aging processing and neurodegeneration and can therefore be employed to monitor disease progression and/or determine effectiveness of therapeutic intervention.

Dynamic suspension culture improves ex vivo expansion of cytokine-induced killer cells by upregulating cell activation and glucose consumption rate

Ex vivo expansion is an effective strategy to acquire cytokine-induced killer (CIK) cells needed for clinical trials. In this work, the effects of dynamic suspension culture, which was carried out by shake flasks on a shaker, on CIK cells were investigated by the analysis of expansion characteristics and physiological functions, with the objective to optimize the culture conditions for ex vivo expansion of CIK cells. The results showed that the expansion folds of total cells in dynamic cultures reached 69.36 ± 30.36 folds on day 14, which were significantly higher than those in static cultures (9.24 ± 1.12 folds, P < 0.05), however, the proportions of CD3+ cells and CD3+CD56+ cells in both cultures were similar, leading to much higher expansion of CD3+ cells and CD3+CD56+ cells in dynamic cultures. Additionally, expanded CIK cells in two cultures possessed comparable physiological functions. Notably, significantly higher percentages of CD25+ cells and CD69+ cells were found in dynamic cultures (P < 0.05). Besides, much higher glucose consumption rate of cells (P < 0.05) but similar YLac/gluc were observed in dynamic cultures. Further, cells in dynamic cultures had better glucose utilization efficiency. Together, these results suggested that dynamic cultures improved cell activation, then accelerated glucose consumption rate, which enhanced cell expansion and promoted glucose utilization efficiency of cells.

Assimilation of formic acid and CO2 by engineered Escherichia coli equipped with reconstructed one-carbon assimilation pathways

Gaseous one-carbon (C1) compounds or formic acid (FA) converted from CO2 can be an attractive raw material for bio-based chemicals. Here, we report the development of Escherichia coli strains assimilating FA and CO2 through the reconstructed tetrahydrofolate (THF) cycle and reverse glycine cleavage (gcv) pathway. The Methylobacterium extorquens formate-THF ligase, methenyl-THF cyclohydrolase, and methylene-THF dehydrogenase genes were expressed to allow FA assimilation. The gcv reaction was reversed by knocking out the repressor gene (gcvR) and overexpressing the gcvTHP genes. This engineered strain synthesized 96% and 86% of proteinogenic glycine and serine, respectively, from FA and CO2 in a glucose-containing medium. Native serine deaminase converted serine to pyruvate, showing 4.5% of pyruvate-forming flux comes from FA and CO2 The pyruvate-forming flux from FA and CO2 could be increased to 14.9% by knocking out gcvR, pflB, and serA, chromosomally expressing gcvTHP under trc, and overexpressing the reconstructed THF cycle, gcvTHP, and lpd genes in one vector. To reduce glucose usage required for energy and redox generation, the Candida boidinii formate dehydrogenase (Fdh) gene was expressed. The resulting strain showed specific glucose, FA, and CO2 consumption rates of 370.2, 145.6, and 14.9 mg⋅g dry cell weight (DCW)-1⋅h-1, respectively. The C1 assimilation pathway consumed 21.3 wt% of FA. Furthermore, cells sustained slight growth using only FA and CO2 after glucose depletion, suggesting that combined use of the C1 assimilation pathway and C. boidinii Fdh will be useful for eventually developing a strain capable of utilizing FA and CO2 without an additional carbon source such as glucose.