Various Concentrations Of Glucose Research Articles

One-pot HTST synthesis of responsive fluorescent ZnO@apo-enzyme composite microgels for intracellular glucometry.

Responsive fluorescent microgels, that can selectively, reversibly, and rapidly convert the fluctuation in intracellular glucose level into fluorescence signal, have the potential use for intracellular glucometry to promote the understanding of physiology. Herein, we report one-pot synthesis of such a responsive fluorescent composite microgels, which is made of a representative apo-enzyme, apo-glucose oxidase (apo-GOx), interpenetrated in a composite gel network that is comprised of ZnO quantum dots covalently bonded onto crosslinked poly(ethylene glycol) dimethacrylate. The key of this one-pot synthesis is applying a high-temperature short-time heating (HTST) method, so that the naturally dynamic profile of apo-GOx can be maintained and harnessed on the composite microgels to allow the highly selective response to glucose over a glucose concentration range of 0–20 mM. While the composite microgels can undergo volume phase transitions and convert both an increase and a decrease in glucose concentration into fluorescence signal shortly (<1 s), the changes in average hydrodynamic diameter and fluorescence of the composite microgels can be fully reversible even after twenty cycles of adding/removing glucose, indicating a reversible and rapid time response to the glucose concentration variations. With the composite microgels as biosensors, the fluorescence of the composite microgels embedded in the model cancer cells B16F10 can be modulated in response to intracellular glucose level variations, which are derived from a change in glucose concentration in the culture medium by an external supply, or that can be triggered by biochemical reactions (with the β-galactosidase catalysed hydrolysis of lactose as a model reaction for achieving increased glucose levels, and the GOx catalysed oxidation of glucose for achieving decreased glucose levels).

Hypoxia and hyperglycaemia determine why some endometrial tumours fail to respond to metformin

BackgroundHigh expression of Ki67, a proliferation marker, is associated with reduced endometrial cancer-specific survival. Pre-surgical metformin reduces tumour Ki-67 expression in some women with endometrial cancer. Metformin’s anti-cancer activity may relate to effects on cellular energy metabolism. Since tumour hypoxia and glucose availability are major cellular redox determinants, we evaluated their role in endometrial cancer response to metformin.MethodsEndometrial cancer biopsies from women treated with pre-surgical metformin were tested for the hypoxia markers, HIF-1α and CA-9. Endometrial cancer cell lines were treated with metformin in variable glucose concentrations in normoxia or hypoxia and cell viability, mitochondrial biogenesis, function and energy metabolism were assessed.ResultsIn women treated with metformin (n = 28), Ki-67 response was lower in hypoxic tumours. Metformin showed minimal cytostatic effects towards Ishikawa and HEC1A cells in conventional medium (25 mM glucose). In low glucose (5.5 mM), a dose-dependent cytostatic effect was observed in normoxia but attenuated in hypoxia. Tumours treated with metformin showed increased mitochondrial mass (n = 25), while in cultured cells metformin decreased mitochondrial function. Metformin targets mitochondrial respiration, however, in hypoxic, high glucose conditions, there was a switch to glycolytic metabolism and decreased metformin response.ConclusionsUnderstanding the metabolic adaptations of endometrial tumours may identify patients likely to derive clinical benefit from metformin.

A Minimally Invasive Implantable Sensor for Continuous Wireless Glucose Monitoring Based on a Passive Resonator

An implantable biosensor for the long-range continuous glucose monitoring is proposed in this letter. A fully passive, miniaturized circuit composed of an LC (inductor–capacitor) tank resonator with a volume of 16 mm $^3$ is developed. This passive circuit can be implanted under the human skin, where the interstitial dermal fluid surrounds the LC tank resonator. Variations in glucose concentration result in variations in the permittivity of the fluid. In turn, this variation changes the capacitance of the LC tank resonator and, thus, its resonant frequency. The change in the resonant frequency is observed by the inductively coupled reader antenna located outside the tissue. Measurements are performed for various glucose concentrations in deionized water and human serum albumin, to check the validity of the proposed method in the presence of skin and fat phantom tissues. The results indicate a linear variation of the sensor's resonant frequency with respect to the glucose concentration within the range 0–500 mg/dL and a sensitivity of about 150 kHz/(mg/dL). Measurement results are reliable up to a distance of 10 mm between the reader and the sensor.

Simultaneous Adsorption and Biodegradation of Reactive Dyes using Jatropha Deoiled Cakes

Endemic pollution problems due to discharge of wastewaters are affecting all the aspects of human life. The poor quality effluents coming from industries is destroying the fragile ecosystem, leading to various apprehensions amongst researchers and scientific communities. Treatment of wastewaters have become an urgent need of the society, which cannot be ignored. Incineration, absorption on solid matrices and biological treatment are some of the effluent treatment methods available. These methods, however, have their own disadvantages. This work explores the application of jatropha deoiled cakes on the concurrent adsorption and biological degradation of reactive dyes. Reactive blue, reactive yellow, reactive red were used for the experiments. The combined experiments were tested for effect of glucose concentrations as well as initial concentrations. Glucose concentrations of 1 g/l, 2 g/l and 3 g/l were taken. All the dyes were varied from 100 ppm to 600 ppm. It was observed that combined degradation yielded higher degradation compared to biological degradation alone. The degradation rate varied with the variation of glucose concentration and it also varied with the initial concentration.

High Glucose Affects the Cytotoxic Potential of Rapamycin, Metformin and Hydrogen Peroxide in Cultured Human Mesenchymal Stem Cells.

Oxidative stress and chronic hyperglycemia are two major side effects of type 2 diabetes affecting all cell types including mesenchymal stem cells (MSCs). As a cell therapy choice, understanding the behavior of MSCs will provide crucial information for efficient treatment. Placental mesenchymal stem cells were treated with various concentrations of glucose, metformin, rapamycin, and hydrogen peroxide to monitor their viability and cell cycle distribution. Cellular viability was examined via the MTT assay. Cell cycle distribution was studied by propidium iodide staining and apoptosis was determined using Annexin Vpropidium iodide staining and flow cytometry. Involvement of potential signaling pathways was evaluated by Western blotting for activation of Akt, P70S6K, and AMPK. The results indicated that high glucose augmented cell viability and reduced metformin toxic potential. However, the hydrogen peroxide and rapamycin toxicities were exacerbated. Our findings suggest that high glucose concentration has a major effect on placental mesenchymal stem cell viability in the presence of rapamycin, metformin and hydrogen peroxide in culture.

Controlling the AP Controller: Controller Performance Assessment and Modification.

Despite recent advances in closed-loop control of blood glucose concentration (BGC) in people with type 1 diabetes (T1D), online performance assessment and modification of artificial pancreas (AP) control systems remain a challenge as the metabolic characteristics of users change over time. A controller performance assessment and modification system (CPAMS) analyzes the glucose concentration variations and controller behavior, and modifies the parameters of the control system used in the multivariable AP system. Various indices are defined to quantitatively evaluate the controller performance in real time. Controller performance assessment and modification system also incorporates online learning from historical data to anticipate impending disturbances and proactively counteract their effects. Using a multivariable simulation platform for T1D, the CPAMS is used to enhance the BGC regulation in people with T1D by means of automated insulin delivery with an adaptive learning predictive controller. Controller performance assessment and modification system increases the percentage of time in the target range (70-180) mg/dL by 52.3% without causing any hypoglycemia and hyperglycemia events. The results demonstrate a significant improvement in the multivariable AP controller performance by using CPAMS.

Regulation of proteoglycan production by varying glucose concentrations controls fiber formation in tissue engineered menisci

Fibrillar collagens are highly prevalent in the extracellular matrix of all connective tissues and therefore commonly used as a biomaterial in tissue engineering applications. In the native environment, collagen fibers are arranged in a complex hierarchical structure that is often difficult to recreate in a tissue engineered construct. Small leucine rich proteoglycans as well as hyaluronan binding proteoglycans, aggrecan and versican, have been implicated in regulating fiber formation. In this study, we modified proteoglycan production in vitro by altering culture medium glucose concentrations (4500, 1000, 500, 250, and 125 mg/L), and evaluated its effect on the formation of collagen fibers inside tissue engineered meniscal constructs. Reduction of extracellular glucose resulted in a dose dependent decrease in total sulfated glycosaminoglycan (GAG) production, but minimal decreases of decorin and biglycan. However, fibromodulin doubled in production between 125 and 4500 mg/L glucose concentration. A peak in fiber formation was observed at 500 mg/L glucose concentration and corresponded with reductions in total GAG production. Fiber formation reduction at 125 and 250 mg/L glucose concentrations are likely due to changes in metabolic activity associated with a limited supply of glucose. These results point to proteoglycan production as a means to manipulate fiber architecture in tissue engineered constructs. Statement of significanceFibrillar collagens are highly prevalent in the extracellular matrix of all connective tissues; however achieving appropriate assembly and organization of collagen fibers in engineered connective tissues is a persistent challenge. Proteoglycans have been implicated in regulating collagen fiber organization both in vivo and in vitro, however little is known about methods to control proteoglycan production and the subsequent fiber organization in tissue engineered menisci. Here, we show that media glucose content can be optimized to control proteoglycan production and collagen fiber assembly, with optimal collagen fiber assembly occurring at sub-physiologic levels of glucose.

SNF1 controls the glycolytic flux and mitochondrial respiration.

The switch between mitochondrial respiration and fermentation as the main ATP production pathway through an increase glycolytic flux is known as the Crabtree effect. The elucidation of the molecular mechanism of the Crabtree effect may have important applications in ethanol production and lay the groundwork for the Warburg effect, which is essential in the molecular etiology of cancer. A key piece in this mechanism could be Snf1p, which is a protein that participates in the nutritional response including glucose metabolism. Thus, this work aimed to recognize the role of the SNF1 gene on the glycolytic flux and mitochondrial respiration through the glucose concentration variation to gain insights about its relationship with the Crabtree effect. Herein, we found that SNF1 deletion in Saccharomyces cerevisiae cells grown at 1% glucose, decreased glycolytic flux, increased NAD(P)H concentration, enhanced HXK2 gene transcription, and decreased mitochondrial respiration. Meanwhile, the same deletion increased the mitochondrial respiration of cells grown at 10% glucose. Altogether, these findings indicate that SNF1 is important to respond to glucose concentration variation and is involved in the switch between mitochondrial respiration and fermentation.

Tricore photonic crystal fibre based refractive index sensor for glucose detection

An enhanced compact sensitivity of glucose sensor in the presence of human blood using tricore photonic crystal fibre is numerically proposed where one hollow channel filled by analyte acts as liquid core and remain two cores considering the silica substrate. The uniqueness of this structure is single material substrate and capable of tuning its sensitivity with minimum variation of glucose concentration (g/l) to detect the low level presence of glucose in the human blood. The transmission spectrum shows the maximum wavelength shift for x -polarisation at 470 nm, and 440 nm for y -polarisation to the response of refractive index of glucose resulting enhanced average sensitivity of 23,267.33 nm/RIU achieved at 470 nm of wavelength shift. The entire analysis and its mechanism of the proposed structure are applied with help of finite-element method.

Noninvasive Glucose Sensor Based on Parity-Time Symmetry

In recent years, parity-time ($P\phantom{\rule{0}{0ex}}T$) symmetry has been explored in several areas of physics, including quantum mechanics, optics, and acoustics. Now medicine can reap the benefits: Utilizing anisotropic transmission resonances supported by a $P\phantom{\rule{0}{0ex}}T$-symmetric structure, this study develops a noninvasive glucose sensor operating in the microwave band. Analytical results and full-wave simulations indicate that the resonance shift can be made fairly linear with respect to variations in glucose concentration, overcoming traditional limitations of passive-sensing schemes. Notably, this detection mechanism offers the possibility of precise sensors for other applications as well.

Electrochemical Glucose Quantification as a Strategy for Ethanolic Fermentation Monitoring

The possibility of using an electrochemical biosensor, using screen-printed electrodes modified with a carbonaceous material and a commercial kit for the determination of glucose, to monitor an ethanolic fermentation was analyzed. The determination is based on the electrochemical oxidation reaction of NADH that occurs at a potential where the components of the kit do not generate a current signal, even in the presence of the fermentation medium. The electrochemical system was used to analyze the variation of glucose concentration during a laboratory-scale fermentation. The results were contrasted with the variation of standard characterization parameters such as pH, total soluble solids (TSS), the viability of the yeast, and concentration of ethanol produced. Of these values, the total soluble solids should be related to the concentration of glucose obtained by the electrochemical sensor, however, this last measure is more specific for sugar since the TSS refers to all soluble solids. The obtained results allow us to verify the usefulness of the electrochemical method for real-time monitoring of a fermentation.

The impact of exenatide (a GLP-1 agonist) on markers of inflammation and oxidative stress in normal human astrocytes subjected to various glycemic conditions.

GLP-1 agonists such as exenatide and liraglutide are novel drugs for the treatment of diabetes and obesity. While improvements in glycemic control can rely on an incretin effect, the mechanisms behind the loss of weight following therapy have yet to be completely elucidated, and seem to be associated with alterations in eating habits, resulting from changes in cytokines e.g. interleukin 1β (IL-1β) and oxidative signaling in the central nervous system (CNS). Increased levels of IL-1β and reactive oxygen species have been demonstrated to exert anorexigenic properties, and astrocytes appear to actively participate in maintaining the integrity of the CNS, which includes the paracrine secretion of inflammatory cytokines and involvement in the redox status. Therefore, the present study decided to explore the influence of exenatide [a glucagon-like peptide 1 (GLP-1 agonist)] on inflammatory and oxidative stress markers in cultured human astrocytes as a potential target for weight reduction therapies. In an experimental setting, normal human astrocytes were subjected to various glycemic conditions, including 40 mg/dl-hypoglycemic, 100 mg/dl-normoglycemic and 400 mg/dl-hyperglycemic, and exenatide, which is a GLP-1 agonist. The involvement of intracellular signaling by a protein kinase A (PKA) in the action of exenatide was estimated using a specific PKA inhibitor-PKI (14-22). The expression levels of IL-1β, nuclear factor kappa κB (NFκB), glial-fibrillary acidic protein (GFAP), p22 NADPH oxidase, glutathione peroxidase, catalase, superoxide dismutase 1, and reactive oxidative species were measured. The present study demonstrated that varying glucose concentrations in the culture media did not affect the protein expression or the level of reactive oxygen species. Conversely, exenatide led to an increase in IL-1β in normoglycemic culture conditions, which was accompanied by the increased expression of p22, glutathione peroxidase and the reduced expression of GFAP. Changes in the expression of IL-1β and p22 were dependent on the activation of PKA. The present study concluded that exenatide predominantly affected astrocytes in normoglycemic conditions, and hypothesize that this impact demonstrated one of novel mechanisms associated with astrocyte signaling that may contribute to weight loss.

Effects of Glucose Concentration on Ethanol Fermentation of White-Rot Fungus Phanerochaete sordida YK-624 Under Aerobic Conditions.

White-rot fungi are microorganisms capable of ethanol fermentation; however, the specific conditions activating ethanol fermentation are unclear in contrast to fermentation by yeasts. In this study, we investigated the conditions favoring ethanol fermentation by the white-rot fungus Phanerochaete sordida YK-624, which is able to produce ethanol from woody material. In aerobic stationary cultivation with various concentrations of glucose (0.8-33g/l), the fungus produced ethanol in media containing an initial glucose concentration of 2.8g/l or higher. The amount of glucose consumption, mycelial weight, and ethanol production on the second day of culture increased in a concentration-dependent manner at low glucose concentrations; however, these were saturated at high concentrations. Biomass yields (growth/glucose consumption) were decreased until the initial glucose concentration increased to 6.0g/l, after which the biomass yields showed constant values at higher concentrations (12-33g/l). On the other hand, ethanol yields increased with decreasing biomass yields. In short shaking cultivation using mycelial suspension, trace amounts of instantaneous aerobic ethanol production were observed with 1.1 and 2.1g/l glucose, but the relative gene expression levels of key enzymes at the pyruvate branch point showed no significant differences between ethanol production and non-production conditions. From these experimental results, it appears that the white-rot fungus P. sordida YK-624 produces ethanol due to overflow in sugar metabolism under aerobic conditions, although P. sordida YK-624 prioritizes glucose utilization for respiratory growth.

Glucose Sensing Using Slot Waveguide-Based SOI Ring Resonator

An optical ring resonator based sensor is proposed for bio-sensing applications. It is applied to glucose level monitoring in blood samples in the range 10 to 200 mg/dl using minimal invasive technique. Two configurations of ring resonator are proposed that are based on ridge and slot waveguide. The average sensitivity of slot ring resonator is observed to be 360 nm/RIU, which is six times higher (60 nm/RIU) than that of ridge ring resonator. Both the sensor configurations are adept to respond to slight variation in glucose concentration, which affects the refractive index and ultimately the spectral shift of the resonator.

Reversible modulation of plasmonic chiral signals of achiral gold nanorods using a chiral supramolecular template.

We report here the fabrication of a multiple stimuli-responsive chiral plasmonic system based on the reversible self-assembly of phenylboronic acid-capped gold nanorods (PBA-Au NRs) guided by a supramolecular glycopeptide mimetic template. The plasmonic chiral signals of PBA-Au NRs can be reversibly switched on and off by temperature, light, pH and glucose concentration variations.

The Effect of Zeitgeber (Fasting and Exercise) on Phase Advance Blood Glucose Circadian Rhythms in Endurance Athletes

Objectives: Fasting is usually associated with changes in the metabolic, psychological and physiological responses of athletes; advancing and/or delaying their biological clock and therefore, affecting their sport performance. The aim of this study was to assess the effect of Ramadan fasting on blood glucose level, mean arterial pressure (MAP), heart rate (HR) and skin temperature in 11 experienced endurance athletes. Methods: The study was conducted during the third and fourth weeks of Ramadan (26 May - 24 June 2017). Eleven northwest African male endurance runners volunteered to participate in this study (mean ± SD: Age 32 ± 8 years, mass 64 ± 5 kg, and height 1.72 ± 0.05 cm). All participants regularly trained between 18:00 - 19:00; aiming to complete their training close to the time of breaking of fast to allow for rapid rehydration and avoiding any health complications. Blood finger-pricking, blood pressure (BP), HR and skin temperature samples were taken every 2 hours over a 24-hour period during the 3rd or 4th weeks of Ramadan. Data were analysed using a two-way repeated measures ANOVA with Bonferroni-adjusted post hoc tests. Results: A clear within-day variation was revealed in blood glucose concentrations and HR (P &lt; 0.05). Blood glucose concentration variation was directly associated with exercise and food intake but significant peaks were also observed prior to breaking fast. These peaks corresponded to the start of athlete’s usual daily routine and suggest the athletes were able to phase advance blood glucose circadian rhythms. Conclusions: The data presented demonstrates the combination of exercise and fasting phase shifted and adjusted the blood glucose concentration to start rising prior to training session.

Effect of dietary supplementation with apple cider vinegar and propionic acid on hemolymph chemistry, intestinal microbiota and histological structure of hepatopancreas in white shrimp, Litopenaeus vannamei

This experiment was conducted to evaluate the effects of dietary supplementation of Apple cider vinegar (ACV) and propionic acid (PA) on biochemical parameters of hemolymph, intestinal microbiota and histology of hepatopancreas in white shrimp (Litopenaeus vannamei). Five experimental diets were evaluated in this study including diets supplemented with 1.0, 2.0 and 4.0% of ACV, 0.5% propionic acid, and a control diet with no supplements. Shrimps (initial weight of 10.2 ± 0.04 g) in triplicate groups with the density of 25 shrimps per tank were fed the diets for 60 days. At the end of the feeding trial, shrimps fed with ACV and PA supplemented diets had significantly higher total protein level than those fed the control diet (P < 0.05). The number of Vibrio spp., R-cells (lipid storage cells) of hepatopancreas and cholesterol level in shrimps fed the diets containing ACV and PA were lower compared to the control group (P < 0.05). However, there was no remarkable variations in glucose concentration, B-cell number and tubule diameter among the experimental diets (P > 0.05). In addition, shrimps fed the ACV diets had significantly lower total heterotrophic marine bacteria compared to the control or PA groups, and the lowest bacterial number was observed in shrimp fed 4% ACV supplemented diet (P < 0.05). Supplementation of 2 and 4% ACV as well as 0.5% PA in the diet led to a significantly higher calcium concentration than the control treatment (P < 0.05). The lowest triglyceride concentration was observed in the shrimps fed diets containing 2.0 and 4.0% ACV, which resulted in 15 and 20% reduction, respectively (P < 0.05). Overall, the findings indicates that ACV and PA possess antimicrobial activity and demonstrate beneficial effects on health status, so they can be potentially used as feed additive in the feeding of L. vannamei.

In vitro analysis of a microwave sensor for noninvasive glucose monitoring

AbstractIn this article, we present in vitro analysis for a microwave sensor proposed for noninvasive glucose monitoring. The sensor is a microstrip‐fed rectangular slot with a dielectric resonator having an elliptical shape resembling a human thumb. It has been demonstrated experimentally and by simulations that the microwave sensor is capable of detecting variations in glucose concentrations (40‐400 mg/dL) by observing shifts in the sensor's resonant frequencies. A Debye model is first developed to predict permittivity and loss tangent values of given glucose concentrations. Knowledge of such values is essential to facilitate simulation of glucose sensor. The simulations and measuremental results show similar behaviors with respect to resonances in the frequency band of interest, which makes the proposed microwave sensor a potential and convenient choice for noninvasive glucose monitoring.

"Guide Star" Assisted Noninvasive Photoacoustic Measurement of Glucose.

A novel "guide star" assisted photoacoustic (GSPA) method for noninvasive glucose measurement has been proposed. Instead of receiving PA signals that are directly generated by tissue, a virtual photodiode is employed to amplify the PA signal difference regarding amplitude and peak arrival time caused by glucose concentration variations in an indirect way. Being different from traditional PA spectroscopy, this method can improve sensitivity and accuracy by optimizing optical path lengths (or tissue thickness). On the other hand, being superior to near-infrared (NIR) spectroscopy, it utilizes both optical absorption and acoustic propagation velocity information confered by PA signals. Theoretical analysis and simulation have been done to illustrate how the concentration change affects the PA waveform. In vitro experiments on aqueous glucose solution were conducted with concentrations varying in human physiological range (50-350 mg/dL). Performance of quartz cuvettes with 1 mm and 2 mm optical path lengths were compared in terms of correlation quality ( R2), degree of agreement (Bland-Altman plot), and clinical accuracy (Clarke's Error Grid analysis) to demonstrate the scalability of sensitivity provided by the indirect method. Longer optical length shows better sensitivity and accuracy in this case. Moreover, detection was also done on human blood serum to further prove the potential of the proposed method for clinical application. Our proposed method provides a solution to enhance sensitivity, facilitating development of portable and low-cost PA sensors with low power laser diodes for noninvasive glucose monitoring and other applications.

The Effect of Zeitgeber (Fasting and Exercise) on Phase Advance Blood Glucose Circadian Rhythms in Endurance Athletes

ObjectivesFasting is usually associated with changes in the metabolic, psychological and physiological responses of athletes; advancing and/or delaying their biological clock and therefore, affecting their sport performance. The aim of this study was to assess the effect of Ramadan fasting on blood glucose level, mean arterial pressure (MAP), heart rate (HR) and skin temperature in 11 experienced endurance athletes.MethodsThe study was conducted during the third and fourth weeks of Ramadan (26 May - 24 June 2017). Eleven northwest African male endurance runners volunteered to participate in this study (mean ± SD: Age 32 ± 8 years, mass 64 ± 5 kg, and height 1.72 ± 0.05 cm). All participants regularly trained between 18:00 - 19:00; aiming to complete their training close to the time of breaking of fast to allow for rapid rehydration and avoiding any health complications. Blood finger-pricking, blood pressure (BP), HR and skin temperature samples were taken every 2 hours over a 24-hour period during the 3rd or 4th weeks of Ramadan. Data were analysed using a two-way repeated measures ANOVA with Bonferroni-adjusted post hoc tests.ResultsA clear within-day variation was revealed in blood glucose concentrations and HR (P < 0.05). Blood glucose concentration variation was directly associated with exercise and food intake but significant peaks were also observed prior to breaking fast. These peaks corresponded to the start of athlete’s usual daily routine and suggest the athletes were able to phase advance blood glucose circadian rhythms.ConclusionsThe data presented demonstrates the combination of exercise and fasting phase shifted and adjusted the blood glucose concentration to start rising prior to training session.