Role of the gut–brain axis in energy and glucose metabolism

The gastrointestinal tract plays a role in the development and treatment of metabolic diseases. During a meal, the gut provides crucial information to the brain regarding incoming nutrients to allow proper maintenance of energy and glucose homeostasis. This gut–brain communication is regulated by various peptides or hormones that are secreted from the gut in response to nutrients; these signaling molecules can enter the circulation and act directly on the brain, or they can act indirectly via paracrine action on local vagal and spinal afferent neurons that innervate the gut. In addition, the enteric nervous system can act as a relay from the gut to the brain. The current review will outline the different gut–brain signaling mechanisms that contribute to metabolic homeostasis, highlighting the recent advances in understanding these complex hormonal and neural pathways. Furthermore, the impact of the gut microbiota on various components of the gut–brain axis that regulates energy and glucose homeostasis will be discussed. A better understanding of the gut–brain axis and its complex relationship with the gut microbiome is crucial for the development of successful pharmacological therapies to combat obesity and diabetes.Subject terms: Obesity, Type 2 diabetes, Obesity     

Growth rate determination of heterogeneous microbial population in swine manure

The effect of manure concentration on the growth of the heterogeneous microbial population under batch condition was studied. Four manure concentrations were used in the study. The dehydrogenase activity was used as a measure of the active biomass in the manure. The chemical oxygen demand test was used to measure the change in organic material caused by biological activities. The growth curve of the heterogeneous microbial population in swine manure was essentially similar to that of a pure culture grown batchwise in that it had the four principle phases: lag, exponential growth, stationary, and death. The exponential growth phase followed a diauxic growth pattern. High concentration of manure had an inhibitory effect on the microbial growth. Manure diluted less than 1:3 (manure:water) depressed the specific growth rate of the microbial population.     

Unique rate expression for glucose production in C(4) plants

A physicochemical interpretation of a recently formulated temperature-dependent, steady-state rate expression for the production of glucose equivalent in C(4) plants is given here. We show that the rate equation is applicable to a wide range of C(4) plants.     

Effect of Polyglycol Ethers on the Frictional Properties of a Hemispherical Yarn

Russian Journal of General Chemistry - The effect of polyglycol ethers on the frictional properties of a 22 tex 35%wool/65% polyester fiber blend yarn was examined. During external friction the...     

Association between angiotensin-1 converting enzyme gene polymorphism and the metabolic syndrome in a Mexican population

Metabolic Syndrome (MS) is recognized as a cluster of cardiovascular risk factors. All components of MS have a genetic base. Genes of the renin angiotensin system are potential candidate genes for MS. We investigated whether angiotensin converting enzyme (ACE) gene polymorphism increases susceptibility to MS as an entity in a Mexican population. In a cross-sectional study, 514 individuals were studied including 245 patients with MS and 269 subjects without MS criteria. ACE gene polymorphism was detected using PCR. MS was defined according to The National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) criteria, except that the raised fasting plasma glucose 相似文献   

Effect of air change rate on rubber accelerated ageing tests in hot air. Part 1. Preliminary study

Using a multi-cell ageing oven an NR compound was aged for 168 h at 70 °C in air with 3, 8, 10 and 15 air changes per hour. Ageing was evaluated by values of stress at 300% elongation (M 300), tensile strength (TS), elongation at break (EB) and hardness (IRHD). Simultaneously, a similar ageing treatment but in a normal oven at much lower air change rate was carried out. The statistical analysis of results showed that there are significant differences in M300 and TS after ageing among the various air-flows and also in M300 and EB between the results obtained in the normal oven and in the block oven at 3 air changes per hour. There were no significant differences among the cells in the oven nor (except in hardness test prices) in the material subjected to ageing, although it was prepared in several curing operations.     

Binding equilibrium isotope effects for glucose at the catalytic domain of human brain hexokinase

We have utilized tritium isotope effects to probe the in vitro binding equilibrium between glucose and human brain hexokinase (E.C.2.7.1.1). Replacing a backbone hydrogen atom in glucose with tritium can significantly increase or decrease the equilibrium association constant. Specifically, the equilibrium tritium isotope effects are 1.027 +/- 0.002, 0.927 +/- 0.0003, 1.027 +/- 0.004, 1.051 +/- 0.001, 0.988 +/- 0.001, and 1.065 +/- 0.003 for [1-t]-, [2-t]-, [3-t]-, [4-t]-, [5-t]-, and [6,6-t(2)]glucose, respectively. We have shown that the existence of prebinding equilibrium isotope effects can contribute to binding isotope effect studies but that this effect is insignificant for glucose binding to hexokinase. The binding isotope effects are interpreted in the context of structural studies of hexokinase-glucose complexes. Ab initio calculations on 2-propanol with or without a hydrogen bonding partner, in steric collision with formaldehyde or methane, and on ethanol, cyclohexanol and 1-hydroxymethyl-tetrahydropyran are presented to clarify the magnitude of isotope effects possible in such interactions and the accompanying changes in free energy. Position-specific binding isotope effects provide direct evidence of the partial deprotonation and activation of O6 by Asp657, of other hydrogen bonding interactions with ionic residues, and of the steric compression of CH2 by the backbone carbonyl of Ser603.     

Coupling of heart rate with metabolic depression in fish: a radiotelemetric and calorimetric study

This study of the goldfish (Carassius auratus L.) combines two techniques: heat measurements via direct calorimetry and radio telemetry, using small implantable telemetry transmitters (3 g). These record overall metabolic rate, and electrocardiogram (ECG) and heart rate frequency (fHR), respectively. The metabolic rate decreased at hypoxia levels of 40, 20, 10, and 3% air-saturation (AS) almost linearly to 94, 84, 69, and 55% of the standard metabolic rate (SMR), respectively. This implies that metabolic depression is flexible, depending on the supply of oxygen. From the deconvoluted heat-flow signal it can be concluded that the metabolic depression per hypoxia level takes place within 20 min. At 3% AS anaerobic metabolism was strongly activated. The fHR of 34 beats per minute (bpm) at normoxia fell at hypoxia levels of 40, 20, 10, and 3% AS to 26, 22, 14, and 9 bpm, respectively. A correlation coefficient of 0.97 was calculated between the level of metabolic depression and decrease of fHR suggesting a relationship between level of metabolic depression and the HR. These results support the hypothesis that blood flow reduction is the proximate cause for the observed metabolic depression.     

Effect of air change rate on rubber accelerated ageing tests in hot air. Part 2. Ageing of different compounds

Seven different compounds based on NR, SBR, NBR and EPDM were aged at 100 and 125°C, and 3, 6.5 and 10 changes of air per hour, and in a normal oven at much lower air change rate at 100 °C. Ageing was evaluated by tensile strength, elongation at break, stress at intermediate elongation and changes of IRHD after ageing. The statistical analysis of results shows that air change rate has a significant effect on ageing results.     

Model-guided metabolic gene knockout of gnd for enhanced succinate production in Escherichia coli from glucose and glycerol substrates

The metabolic role of 6-phosphogluconate dehydrogenase (gnd) under anaerobic conditions with respect to succinate production in Escherichia coli remained largely unspecified. Herein we report what are to our knowledge the first metabolic gene knockout of gnd to have increased succinic acid production using both glucose and glycerol substrates in E. coli. Guided by a genome scale metabolic model, we engineered the E. coli host metabolism to enhance anaerobic production of succinic acid by deleting the gnd gene, considering its location in the boundary of oxidative and non-oxidative pentose phosphate pathway. This strategy induced either the activation of malic enzyme, causing up-regulation of phosphoenolpyruvate carboxylase (ppc) and down regulation of phosphoenolpyruvate carboxykinase (ppck) and/or prevents the decarboxylation of 6 phosphogluconate to increase the pool of glyceraldehyde-3-phosphate (GAP) that is required for the formation of phosphoenolpyruvate (PEP). This approach produced a mutant strain BMS2 with succinic acid production titers of 0.35 g l⁻¹ and 1.40 g l⁻¹ from glucose and glycerol substrates respectively. This work further clearly elucidates and informs other studies that the gnd gene, is a novel deletion target for increasing succinate production in E. coli under anaerobic condition using glucose and glycerol carbon sources. The knowledge gained in this study would help in E. coli and other microbial strains development for increasing succinate production and/or other industrial chemicals.     

Integrated rate expression for the production of glucose equivalent in C4 green plant and the effect of temperature

A temperature-dependent integrated kinetics for the overall process of photosynthesis in green plants is discussed. The C₄ plants are chosen and in these plants, the rate of photosynthesis does not depend on the partial pressure of O₂. Using some basic concepts like chemical equilibrium or steady state approximation, a simplified scheme is developed for both light and dark reactions. The light reaction rate per reaction center (R′ ₁) in thylakoid membrane is related to the rate of exciton transfer between chlorophyll neighbours and an expression is formulated for the light reaction rate R′ ₁. A relation between R′ ₁ and the NADPH formation rate is established. The relation takes care of the survival probability of the membrane. The CO₂ saturation probability in bundle sheath is also taken into consideration. The photochemical efficiency (ϕ) is expressed in terms of these probabilities. The rate of glucose production is given by R _glucose = (8/3)(R′ ₁ v _L )ϕ(T) _g (T) ([G3P]/[P _i]² _leaf)_SS Q _{G3P→glucose} where g is the activity quotient of the involved enzymes, and G3P represent glycealdehyde-3-phosphate in steady state. A Gaussian distribution for temperature-dependence and a sigmoid function for de-activation are incorporated through the quotient g. In general, the probabilities are given by sigmoid curves. The corresponding parameters can be easily determined. The theoretically determined temperature-dependence of photochemical efficiency and glucose production rate agree well with the experimental ones, thereby validating the formalism.     

Thermobiochemical evidence for the rapid metabolic rate in hybridoma cells genetically engineered to overexpress the anti-apoptotic protein bcl-2 in batch culture

A serious problem in the culture of animal cells to produce therapeutic proteins is apoptosis (programmed cell death) because it restricts the ability of the cell culture to yield the heterologous material. One means to delay apoptosis is genetically to engineer the anti-apoptotic gene bcl-2 into the genome. This had been adopted elsewhere to give TB/C3 hybridoma cells that overexpressed bcl-2 (pEF bcl-2-MC1neopA plasmid) and a control, pEF, which contained a nonsense sequence (pEF-MC1neopA). In the spinner cultures used in the present investigation, bcl-2 cells grew for 60 h to give greater cell density at a faster specific rate and with prolonged better viability than the controls in which, after 36 h, the membrane integrity and the apoptotic index of the cells declined rapidly leading to death. Prior to 36 h, production of the monoclonal antibody was only slightly higher in the pEF control giving little evidence for the metabolic burden of its production on antibody synthesis. Bcl-2 synthesis, however, was associated with 125% increase in heat flow rate (HFR) measured in the chemically (triacetin) calibrated batch microcalorimeter. HFR is a function of the metabolic rate and it is suggested that its greater level in the bcl-2 cells than the control was caused by the increased protein production due to the bcl-2 gene expression. The bcl-2 cells had an increased lactate flux compared with the control. The calorimetric-respirometric (CR) ratio confirmed the likelihood that glycolysis rather than glutaminolysis was the primary reason for this increase. It may be due to the limitation in mitochondrial capacity and/or the paucity of biosynthetic precursors leading to production of them from glucose.The stationary liquid phase balance (SLPB) was shown to be the appropriate on-line method to measure the oxygen uptake rate (OUR) in the dilute cell suspensions grown in the tank bioreactor. The metabolic rate expressed as HFR was measured in a customised flow microcalorimeter, which had been calibrated using the enthalpy of hydrolysis produced by the new test reaction using methyl paraben. Both HFR and OUR declined before the decrease in cell density in batch culture, indicating that they were sensitive indicators of deteriorating environmental conditions. However, neither proved to be an early detector of the onset of apoptosis.     

Simulation of the glass transition and physical ageing

A kinetic model simulating the glass transition and enthalpic relaxation in poly(3-hydroxybutyrate) is introduced. The model is based on the concept that enthalpic relaxation or physical ageing is a continuation of the glass forming process and uses the KWW function to describe the glass formation process and the subsequent ageing of the glass. Non-linearity is introduced by incorporating a dependence of the relaxation time on the fictive temperature. The effects of non-linearity on the distribution of relaxation times and the physical ageing process are investigated together with the development of the endothermic ageing peak at the glass transition with increasing extents of ageing.     

Studies on the thermal ageing of organic coatings

The ageing of organic protective coatings depends on environmental impacts and is associated with a variety of ichemical and physical processes. The results of former thermal ageing studies indicate that evaporation and polymer degradation are the decisive processes for changes in coating properties. For the verification of these assumptions the impact of - the thermal exposure temperature T_L and - the length of the exposure time t_L on properties of clear lacquer coatings was determined by further studies. The gradation of T_L was aimed at creating conditions where on the one hand only evaporation processes occur, while on the other hand evaporation and polymer degradation reactions occur in parallel. The objective was to find the time t_L and the temperature T_L at which degradation starts to prevail.     

Study of the copper effect in iron-gall inks after artificial ageing

Iron-gall inks consist of a mixture of vitriols (sulphates of certain metals), gall nut extracts and arabic gum. The association of the iron(II) sulphate present in vitriols, and the gallic acids present in the gall nut extracts induces, after exposure to oxygen, the formation of dark coloured compounds of ink. In addition to iron, this kind of inks contains other metals, such as copper, zinc, and nickel. Among them, copper could be considered the most important because, owing to its catalytic ability, it can be involved in the processes concerning formation and stability of iron complexes, which are responsible for the ink dark colour. For this purpose, four different iron-gall inks containing increasing amounts of copper sulphate were prepared according to a traditional receipt and applied on paper supports. The ink-stained paper specimens were subjected to an intense analytical program to investigate their chemical and physical modifications after artificial ageing (both temperature/humidity and ultraviolet light ageing). The role of copper in the iron-gall inks was evaluated using optical microscopy, colorimetric measurements, X-ray fluorescence (XRF), X-ray diffraction analysis (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX) and Fourier transform infrared spectroscopy (FTIR). For the evaluation of the oxidation state of iron and copper, X-ray absorption spectroscopy (XANES) was used. All results indicate that the presence of copper in iron-gall ink causes colour variation, affects the migratory behaviour of iron in the paper, increases the formation of secondary products particularly when ageing process based on temperature/humidity variations is considered.     

Chemical polymerization of m-phenylenediamine, in the presence of glucose oxidase, produces an enzyme-retaining electrooxidisable polymer used to produce a biosensor for amperometric detection of glucose from brain dialysate

A new procedure involving chemical polymerization of a monomer of m-phenylenediamine (m-ppd) containing glucose oxidase (GOx) and subsequent electro-synthesis of the functional GOx containing polymer onto platinum needle electrodes (PTNE) was used for the amperometric analysis of glucose concentration in brain dialysates. Monomer solutions of o-phenylenediamine (o-ppd) and m-ppd were polymerized by low concentrations of glutaraldehyde (GA) and precipitated from solution. The 1,3 position of the amines on the benzene was amenable to stable polymerization by GA but polymerization of o-ppd (1,2 position) by GA was unstable and degraded. Polymerization of m-ppd appears to proceed by dehydration synthesis. GA induced polymerization of m-ppd polymer in the presence of GOx produced a polymer with strongly bound, functional GOx. This GOx-m-ppd polymer formed a stable matrix that was effectively employed in flow injection analysis (FIA) of glucose. If maintained under O(2) free atmosphere after chemical polymerization, the GOx-m-ppd polymer retained the ability to be electropolymerized. PTNE coated with GOx-m-ppd polymer by repeated dip/amperometry produced stable, sensitive amperometric glucose sensors with good interference exclusion properties and long shelf life. Scanning EM demonstrated that amperometry modified the structure of the GOx-m-ppd on the PTNE surface. GOx-m-ppd PTNE glucose sensors and bare PTNE were placed in a radial flow cell and FIA was employed for the simultaneous measurement of glucose and ascorbic acid, respectively, from dialysates of brain tissue.     

基于液相色谱与质谱联用的代谢组学及磷脂轮廓分析在糖代谢异常研究中的应用

糖代谢异常由于其发病率的升高和影响人类的生活质量而日益受到科学研究者的关注。实验中利用液相色谱与质谱(LC-MS)联用技术对糖代谢异常分别进行了代谢组学和磷脂轮廓分析,研究了糖代谢异常中的两个阶段——空腹血糖受损(IFG)和初诊糖尿病(NDD)的代谢差异情况。首先从LC-MS采集到血浆中代谢组学分析及磷脂轮廓分析的原始谱图,通过软件的峰匹配等步骤得到峰表,之后利用多种统计分析方法进行数据分析,通过正交校正的偏最小二乘法(OSC-PLS)对样品进行分型,根据模型的变量重要因子(VIP)、显著性差异检验结果等筛选出差异性代谢物。结果显示: NDD组比IFG组与对照组(N组)比较存在更明显的代谢差异,发生变化的化合物主要为游离脂肪酸、溶血磷脂酰胆碱、磷脂酰乙醇胺、鞘磷脂和磷脂酰胆碱等。     

Gravimetric studies of ageing in microporous zirconia gels

The work reported in this paper demonstrates the use of the gravimetric techniques to characterize the irreversible textural changes in a hydrous oxide system. A series of microporous zirconia gels were prepared under strictly controlled conditions in the aqueous medium. The porosities of the gels have been characterized by the studies of the nitrogen and water adsorption isotherms. The water sorption isotherms indicated an ageing phenomenon demostrated by the negative low pressure hysteresis.Further, the hydrous gels which were initially outgassed at 298K (at 10⁻⁴ torr for 48 h) showed, on subsequent exposure to water vapour, an enhanced desorption ( >30% in excess of the total amount sorbed.The mechanism of this ageing process is not obvious, but it is suggested that the loss in weight induced by almost saturated water vapour arises from the withdrawal of the molecular water present within the elementary particles of the hydrous oxide gels. The removal of the sorbed water results in the closure of micropores.     

Investigation of the uniformity and ageing of integrating spheres

A diode laser device was used to investigate the uniformity and ageing of typical integrating spheres. The device could be rotated about two axes enabling the input laser beam to be positioned sequentially at any point inside the sphere. For each point the resulting reflected beam flux was collected by a photodiode at a fixed position. The measurements were repeated at an interval of several months to determine if the degree of uniformity had changed. Three spheres, each incorporating a different internal white reflecting surface, were investigated. The results of sphere uniformity and temporal stability are discussed.