Neurons require glucose uptake and glycolysis in vivo

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In Vivo Evidence for Serine Biosynthesis-Defined Sensitivity of Lung Metastasis,but Not of Primary Breast Tumors,to mTORC1 Inhibition

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Metabolic imaging using hyperpolarized 13C‐pyruvate to assess sensitivity to the B‐Raf inhibitor vemurafenib in melanoma cells and xenografts

Nearly all melanoma patients with a BRAF‐activating mutation will develop resistance after an initial clinical benefit from BRAF inhibition (BRAFi). The aim of this work is to evaluate whether metabolic imaging using hyperpolarized (HP) ¹³C pyruvate can serve as a metabolic marker of early response to BRAFi in melanoma, by exploiting the metabolic effects of BRAFi. Mice bearing human melanoma xenografts were treated with the BRAFi vemurafenib or vehicle. In vivo HP ¹³C magnetic resonance spectroscopy was performed at baseline and 24 hours after treatment to evaluate changes in pyruvate‐to‐lactate conversion. Oxygen partial pressure was measured via electron paramagnetic resonance oximetry. Ex vivo qRT‐PCR, immunohistochemistry and WB analysis were performed on tumour samples collected at the same time‐points selected for in vivo experiments. Similar approaches were applied to evaluate the effect of BRAFi on sensitive and resistant melanoma cells in vitro, excluding the role of tumour microenvironment. BRAF inhibition induced a significant increase in the HP pyruvate‐to‐lactate conversion in vivo, followed by a reduction of hypoxia. Conversely, the conversion was inhibited in vitro, which was consistent with BRAFi‐mediated impairment of glycolysis. The paradoxical increase of pyruvate‐to‐lactate conversion in vivo suggests that such conversion is highly influenced by the tumour microenvironment.     

Combining mechanistic and data‐driven approaches to gain process knowledge on the control of the metabolic shift to lactate uptake in a fed‐batch CHO process

A growing body of knowledge is available on the cellular regulation of overflow metabolism in mammalian hosts of recombinant protein production. However, to develop strategies to control the regulation of overflow metabolism in cell culture processes, the effect of process parameters on metabolism has to be well understood. In this study, we investigated the effect of pH and temperature shift timing on lactate metabolism in a fed‐batch Chinese hamster ovary (CHO) process by using a Design of Experiments (DoE) approach. The metabolic switch to lactate consumption was controlled in a broad range by the proper timing of pH and temperature shifts. To extract process knowledge from the large experimental dataset, we proposed a novel methodological concept and demonstrated its usefulness with the analysis of lactate metabolism. Time‐resolved metabolic flux analysis and PLS‐R VIP were combined to assess the correlation of lactate metabolism and the activity of the major intracellular pathways. Whereas the switch to lactate uptake was mainly triggered by the decrease in the glycolytic flux, lactate uptake was correlated to TCA activity in the last days of the cultivation. These metabolic interactions were visualized on simple mechanistic plots to facilitate the interpretation of the results. Taken together, the combination of knowledge‐based mechanistic modeling and data‐driven multivariate analysis delivered valuable insights into the metabolic control of lactate production and has proven to be a powerful tool for the analysis of large metabolic datasets. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1657–1668, 2015     

Metabolic Imaging Reveals a Unique Preference of Symmetric Cell Division and Homing of Leukemia-Initiating Cells in an Endosteal Niche

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Changes in lactate content in the gills of the mudskippers Periophthalmus chrysospilos and Boleophthalmus boddaerti in response to environmental hypoxia

The gills of Periophthalmus chrysospilos exhibited significantly greater pyruvate kinase and lactate dehydrogenase activities than those of Boleophthalmus boddaerti ( P <0.01). Under the control normoxic condition, the branchial lactate content of the former mudskipper was also significantly greater ( P < 0.01) than that of the latter. After hypoxic exposure, lactate and alanine accumulated in the gills of P. chrysospilos but not B. boddaerti . Succinate and propionate were not detected in the gills of these two mudskippers under the control and hypoxic conditions.     

Metabolic flux maps comparing the effect of temperature on protein and oil biosynthesis in developing soybean cotyledons

Metabolic flux maps developed from ¹³C metabolic flux analysis (¹³C MFA) are effective tools for assessing the response of biological systems to genetic or environmental perturbations, and for identifying possible metabolic engineering targets. Experimental treatments were designed to distinguish between temperature effects prior to, and during incubation in vitro , on primary metabolism in developing soybeans. Biomass accumulation increased with temperature as did carbon partitioning into lipids. The flux through the plastidic oxidative pentose phosphate pathway (pgl^P) relative to sucrose intake remained fairly constant [∼56% (±24%)] when cotyledons were transferred from an optimum growth temperature to varying temperatures in in vitro culture, signifying a rigid node under these conditions. However, pgl^P flux ranged from 57 to 77% of sucrose intake when growth temperature in planta varied and were cultured in vitro at the same temperature (as the plant), indicating a flexible node for this case. The carbon flux through the anaplerotic reactions catalysed by plastidic malic enzyme (me^P), cytosolic phosphoenolpyruvate (PEP) carboxylase and the malate (Mal) transporter from the cytosol to mitochondrion varied dramatically with temperature and had a direct influence on the carbon partitioning into protein and oil from the plastidic pyruvate (Pyr) pool. These results of the in vitro culture indicate that temperature during early stages of development has a dominant effect on establishing capacity for flux through certain components of central carbon metabolism.     

影像学在肾癌靶向治疗中的临床应用价值-现状与展望

肾癌为最常见的肾脏恶性肿瘤,其易复发及易出现远隔转移,靶向治疗已逐渐成为肾癌治疗中不可或缺的治疗手段。由于RECIST标准评价实体瘤疗效具有明显的局限性,临床实践中常使用电子计算机断层扫描(CT)、磁共振成像(MRI)评价疗效。随着技术的不断发展,很多新颖的影像学手段如动态增强超声(DCE-US)、正电子发射断层显像(PET-CT)等可以更准确更早期地评价及预测靶向治疗的疗效。本文对肾癌靶向治疗的影像学现状及展望进行综述。     

Excess exogenous pyruvate inhibits lactate dehydrogenase activity in live cells in an MCT1-dependent manner

Cellular pyruvate is an essential metabolite at the crossroads of glycolysis and oxidative phosphorylation, capable of supporting fermentative glycolysis by reduction to lactate mediated by lactate dehydrogenase (LDH) among other functions. Several inherited diseases of mitochondrial metabolism impact extracellular (plasma) pyruvate concentrations, and [1-¹³C]pyruvate infusion is used in isotope-labeled metabolic tracing studies, including hyperpolarized magnetic resonance spectroscopic imaging. However, how these extracellular pyruvate sources impact intracellular metabolism is not clear. Herein, we examined the effects of excess exogenous pyruvate on intracellular LDH activity, extracellular acidification rates (ECARs) as a measure of lactate production, and hyperpolarized [1-¹³C]pyruvate-to-[1-¹³C]lactate conversion rates across a panel of tumor and normal cells. Combined LDH activity and LDHB/LDHA expression analysis intimated various heterotetrameric isoforms comprising LDHA and LDHB in tumor cells, not only canonical LDHA. Millimolar concentrations of exogenous pyruvate induced substrate inhibition of LDH activity in both enzymatic assays ex vivo and in live cells, abrogated glycolytic ECAR, and inhibited hyperpolarized [1-¹³C]pyruvate-to-[1-¹³C]lactate conversion rates in cellulo. Of importance, the extent of exogenous pyruvate-induced inhibition of LDH and glycolytic ECAR in live cells was highly dependent on pyruvate influx, functionally mediated by monocarboxylate transporter-1 localized to the plasma membrane. These data provided evidence that highly concentrated bolus injections of pyruvate in vivo may transiently inhibit LDH activity in a tissue type- and monocarboxylate transporter-1–dependent manner. Maintaining plasma pyruvate at submillimolar concentrations could potentially minimize transient metabolic perturbations, improve pyruvate therapy, and enhance quantification of metabolic studies, including hyperpolarized [1-¹³C]pyruvate magnetic resonance spectroscopic imaging and stable isotope tracer experiments.     

磁共振动态对比增强联合血清TSGF、ICTP、ALP对骨肿瘤良恶性鉴别和骨恶性肿瘤治疗后的疗效评估价值

摘要 目的：探讨磁共振动态对比增强（DCE-MRI）联合血清肿瘤相关物质（TSGF）、I型胶原羧基吡啶末端肽（ICTP）、碱性磷酸酶（ALP）对骨肿瘤良恶性鉴别和骨恶性肿瘤治疗后的疗效评估价值。方法：选择2020年12月至2022年4月本院收治的骨肿瘤患者163例为研究对象,根据骨肿瘤良恶性分为良性组（74例）和恶性组（89例）,恶性组治疗后根据实体肿瘤疗效评价标准分为疗效良好组和疗效不良组,比较良性组与恶性组、疗效良好组与疗效不良组容量运转常数（Ktrans）、速率常数（Kep）、血管外细胞外间隙容积分数（Ve）及1分钟内初始曲线下面积（iAUC）、TSGF、ICTP、ALP,分析Ktrans、Kep、Ve、iAUC与血清TSGF、ICTP、ALP的相关性,采用受试者工作特征（ROC）曲线分析各指标对骨肿瘤良恶性的预测价值。结果：不同组间Ktrans、Kep、iAUC、TSGF、ICTP、ALP比较,良性组低于恶性组（P＜0.05）,疗效良好组低于疗效不良组（P＜0.05）;DCE-MRI定量参数中的Ktrans、Kep、iAUC与血清TSGF、ICTP、ALP呈正相关（P＜0.05）;Ktrans、Kep、iAUC、TSGF、ICTP、ALP及联合预测骨肿瘤良恶性的曲线下面积（AUC）分别为0.794、0.804、0.744、0.747、0.773、0.828和0.986,各项指标联合预测骨肿瘤良恶性的AUC大于各指标单独预测。结论：DCE-MRI定量参数Ktrans、Kep、iAUC联合血清TSGF、ICTP、ALP对骨肿瘤良恶性具有较高的鉴别价值,此外Ktrans、Kep、iAUC、TSGF、ICTP、ALP越高,恶性骨肿瘤患者治疗后的临床疗效越差。     

Q-Flux: A method to assess hepatic mitochondrial succinate dehydrogenase,methylmalonyl-CoA mutase,and glutaminase fluxes in vivo

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动态增强磁共振成像参数联合CEA、NLR、PLR对宫颈癌患者新辅助化疗疗效的预测价值

摘要 目的：研究动态增强磁共振成像（DCE-MRI）参数联合癌胚抗原（CEA）、中性粒细胞与淋巴细胞比值（NLR）、血小板与淋巴细胞比值（PLR）对宫颈癌患者新辅助化疗疗效的预测价值。方法：选取110例2020年5月到2023年5月在张家口市第一医院接受宫颈癌根治术治疗的宫颈癌患者,根据治疗效果分为有效组和无效组。对比有效组及无效组两组的一般资料、DCE-MRI参数、血清CEA及外周血NLR、PLR。受试者工作特征（ROC）曲线分析DCE-MRI参数联合血清CEA、外周血NLR、PLR对新辅助化疗疗效的预测价值。结果：选取的110例患者中,有效组78例,无效组32例,有效组对比增强率（CER）及转运常数（Ktrans）水平较无效组更低（P＜0.05）,两组的其他DCE-MRI参数速率常数（Kep）、对比剂浓度时间的曲线下面积（IAUGC）、血管外细胞间隙体积百分数（Ve）及最大斜率（Maxslope）比较,差异不显著（P＞0.05）。有效组的血清CEA及外周血NLR、PLR较无效组明显更低（P＜0.05）。CER、Ktrans联合血清CEA及外周血NLR、PLR对新辅助化疗疗效的预测价值最佳,其AUC为0.896,敏感度为0.915,特异度为0.802,均高于各项指标单独检测。结论：DCE-MRI参数联合CEA、NLR、PLR有助于提升对宫颈癌患者新辅助化疗疗效的预测价值。     

动态对比增强磁共振成像联合PLR、NLR预测急性脑梗死短期预后的回顾性研究

摘要 目的：探讨动态对比增强磁共振成像（DCE-MRI）联合血小板与淋巴细胞比值（PLR）、中性粒细胞与淋巴细胞比值（NLR）预测急性脑梗死短期预后的价值。方法：回顾性分析我院从2015年1月～2019年12月收治的80例急性脑梗死患者的临床资料。将所有患者根据改良Rankin量表（mRS）评分差异分作预后良好组（mRS评分≤2分）50例和预后不良组（mRS评分＞2分）30例。比较两组DCE-MRI相关参数[容量转移常数相对值（rKtrans）、速率常数相对值（rKep）、血管外细胞外间隙容积分数相对值（rVe）]、入院时PLR、NLR以及基线资料,采用多因素Logistic回归分析急性脑梗死患者短期预后不良的影响因素。此外,采用受试者工作特征（ROC）曲线分析DCE-MRI、PLR、NLR单独及联合预测急性脑梗死短期预后的效能。结果：预后良好组各项DCE-MRI参数均明显高于预后不良组（P＜0.05）。预后良好组PLR、NLR、年龄以及入院时美国国立卫生研究院脑卒中量表（NIHSS）评分均低于预后不良组（P＜0.05）。经多因素Logistic回归分析可得：PLR、NLR、年龄以及入院时NIHSS评分均是急性脑梗死患者短期预后不良的危险因素（OR＞1,P＜0.05）。DCE-MRI联合PLR、NLR预测急性脑梗死短期预后不良的曲线下面积、敏感度、特异度以及约登指数均高于上述单项预测。结论：DCE-MRI联合PLR、NLR预测急性脑梗死短期预后不良的效能较高,具有一定应用价值。     

The metabolic flux phenotype of heterotrophic Arabidopsis cells reveals a flexible balance between the cytosolic and plastidic contributions to carbohydrate oxidation in response to phosphate limitation

Understanding the mechanisms that allow plants to respond to variable and reduced availability of inorganic phosphate is of increasing agricultural importance because of the continuing depletion of the rock phosphate reserves that are used to combat inadequate phosphate levels in the soil. Changes in gene expression, protein levels, enzyme activities and metabolite levels all point to a reconfiguration of the central metabolic network in response to reduced availability of inorganic phosphate, but the metabolic significance of these changes can only be assessed in terms of the fluxes supported by the network. Steady‐state metabolic flux analysis was used to define the metabolic phenotype of a heterotrophic Arabidopsis thaliana cell culture grown on a Murashige and Skoog medium containing 0, 1.25 or 5 mm inorganic phosphate. Fluxes through the central metabolic network were deduced from the redistribution of ¹³C into metabolic intermediates and end products when cells were labelled with [1‐¹³C], [2‐¹³C], or [¹³C₆]glucose, in combination with ¹⁴C measurements of the rates of biomass accumulation. Analysis of the flux maps showed that reduced levels of phosphate in the growth medium stimulated flux through phosphoenolpyruvate carboxylase and malic enzyme, altered the balance between cytosolic and plastidic carbohydrate oxidation in favour of the plastid, and increased cell maintenance costs. We argue that plant cells respond to phosphate deprivation by reconfiguring the flux distribution through the pathways of carbohydrate oxidation to take advantage of better phosphate homeostasis in the plastid.     

Functional Magnetic Resonance Imaging Investigation of the Effects of Neurofeedback Training on the Neural Bases of Selective Attention and Response Inhibition in Children with Attention-Deficit/Hyperactivity Disorder

Two functional magnetic resonance imaging (fMRI) experiments were undertaken to measure the effect of neurofeedback training (NFT), in AD/HD children, on the neural substrates of selective attention and response inhibition. Twenty unmedicated AD/HD children participated to these experiments. Fifteen children were randomly assigned to the Experimental (EXP) group whereas the other five children were randomly assigned to the Control (CON) group. Only subjects in the EXP group underwent NFT. EXP subjects were trained to enhance the amplitude of the SMR (12–15 Hz) and beta 1 activity (15–18 Hz), and decrease the amplitude of theta activity (4–7 Hz). Subjects from both groups were scanned one week before the beginning of NFT (Time 1) and 1 week after the end of NFT (Time 2), while they performed a “Counting Stroop” task (Experiment 1) and a Go/No-Go task (Experiment 2). At Time 1, in both groups, the Counting Stroop task was associated with significant activation in the left superior parietal lobule. For the Go/No-Go task, no significant activity was detected in the EXP and CON groups. At Time 2, in both groups, the Counting Stroop task was associated with significant activation of the left superior parietal lobule. This time, however, there were significant loci of activation, in the EXP group, in the right ACC, left caudate nucleus, and left substantia nigra. No such activation loci were seen in CON subjects. For the Go/No-Go task, significant loci of activation were noted, in the EXP group, in the right ventrolateral prefrontal cortex, right ACcd, left thalamus, left caudate nucleus, and left substantia nigra. No significant activation of these brain regions was measured in CON subjects. These results suggest that NFT has the capacity to functionally normalize the brain systems mediating selective attention and response inhibition in AD/HD children.     

记忆训练联合电针疗法对全脑放疗患者认知功能、健康相关生命质量和颅脑磁共振灌注成像参数的影响

摘要 目的：探讨记忆训练联合电针疗法对全脑放疗患者认知功能、健康相关生命质量和颅脑磁共振灌注成像参数的影响。方法：选择江南大学附属医院2020年3月～2022年1月期间收治的全脑放疗患者94例,根据随机数字表法分为研究组（常规干预、记忆训练联合电针疗法）和对照组（常规干预）,各为47例。对比两组认知功能、健康相关生命质量和颅脑磁共振灌注成像参数的变化。结果：治疗1周、2周、3周、4周后,两组蒙特利尔认知功能检查量表（MoCA）和简易精神状态量表（MMSE）评分均较治疗前逐渐下降,但研究组各时间点MoCA、MMSE评分高于对照组（P<0.05）。治疗4周后,两组健康相关生命质量量表（HRQoL）各维度评分及总分均较治疗前升高,且研究组上述评分均高于对照组（P<0.05）。治疗4周后,两组颅脑平均脑血容量（CBV）值和平均脑血流量（CBF）值均较治疗前下降,但研究组上述值高于对照组（P<0.05）。结论：记忆训练联合电针疗法可减缓全脑放疗后导致的认知功能损害,并提升患者的健康相关生命质量,可能与调节脑血容量、脑血流量有关。     

MRS glucose mapping and PET joining forces: re‐evaluation of the lumped constant in the rat brain under isoflurane anaesthesia

Although numerous positron emission tomography (PET) studies with ¹⁸F‐fluoro‐deoxyglucose (FDG) have reported quantitative results on cerebral glucose kinetics and consumption, there is a large variation between the absolute values found in the literature. One of the underlying causes is the inconsistent use of the lumped constants (LCs), the derivation of which is often based on multiple assumptions that render absolute numbers imprecise and errors hard to quantify. We combined a kinetic FDG‐PET study with magnetic resonance spectroscopic imaging (MRSI) of glucose dynamics in Sprague–Dawley rats to obtain a more comprehensive view of brain glucose kinetics and determine a reliable value for the LC under isoflurane anaesthesia. Maps of T_max/CMR_glc derived from MRSI data and T_max determined from PET kinetic modelling allowed to obtain an LC‐independent CMR_glc. The LC was estimated to range from 0.33 ± 0.07 in retrosplenial cortex to 0.44 ± 0.05 in hippocampus, yielding CMR_glc between 62 ± 14 and 54 ± 11 μmol/min/100 g, respectively. These newly determined LCs for four distinct areas in the rat brain under isoflurane anaesthesia provide means of comparing the growing amount of FDG‐PET data available from translational studies.