Various Concentrations Of Glucose Research Articles

Factors Influencing Escherichia coli and Enterococcus durans Growth in Parenteral Nutrition With and Without Lipid Emulsion to Inform Maximum Duration of Infusion Policy Decisions

Recommendations effectively restrict the infusion duration of lipid-containing parenteral nutrition (PN) from a single bag, purportedly because it encourages growth of potential microbial contaminants more than lipid-free PN. Since other variables, including osmolarity, may independently affect microbial growth, this study examined variables affecting growth of Escherichia coli and Enterococcus durans in PN infusates. Growth of E coli and E durans was assessed in quadruplicate in 12 different PN infusates, with and without lipid, in varying glucose concentrations. Results are presented as mean log10 colony-forming units (cfu)/mL ± SEM at 48 hours. The log10cfu/mL of both E coli and E durans in PN increased considerably after adjustment for baseline log10cfu/mL and pH, from 1.093 to 2.241 (P < .001) and from 0.843 to 3.451 (P < .001) respectively. Growth of each microorganism was independently increased by lipid inclusion, or increasing the proportion of nonnitrogen energy from lipid, and reduced by raising the glucose concentration or energy density. Increasing the osmolarity of lipid-PN with glucose or sodium chloride reduced growth but only significantly for sodium chloride (E coli, P = .025; E durans, P = .045). Induced changes in pH affected the growth of the 2 organisms differently. The presence of lipid and an increasing proportion of energy from lipid in PN favored the growth of E coli and E durans. Osmolarity changes and the nutrient type causing these changes independently affect the growth of these microbes. Each effect needs to be considered when establishing guidelines based on the growth of potential contaminants in different types of PN.

Oxidative stress and proinflammatory role of pancreatic stellate cells in response to tobacco and alcohol

s / Pancreatolog S54 Aims: To investigate the effects of LPS and hyperglycemia on PSC activation and effects of simvastatin on LPS induced PSC activation. Materials & methods: Primary cultures of rat PSCs were exposed to various concentrations of glucose and LPS with/without simvastatin. Quantification of proliferation was performed by Brd-U assay. PSC activation was assessed by expression of a-SMA and extracellular signal-regulated kinase (ERK) using Western blot. Results: LPS induced activation and proliferation of PSC. However, glucose did not affect PSC proliferation. The proliferative effect of LPS on PSC was not affected by glucose concentration in culture media. Simvastatin inhibited LPS induced activation and proliferation of PSC. The proliferative effect of LPS was mediated by activation of Erk 1/2 pathwaywhich was effectively inhibited by simvastatin. Conclusion: This study shows that LPS is one of the activating factors toward PSC. Endotoxemia which is frequently encountered in the clinical settings of acute and chronic pancreatitis may act as a triggering factor for initiating and persisting pancreatic fibrosis. Simvastain could be a therapeutic agent for preventing pancreatic fibrosis.

Physiological Constants of the Entomopathogenic Bacterium Xenorhabdus nematophila Determined by Microbial Growth Kinetics.

Xenorhabdus nematophila, an entomopathogenic bacterium that symbiotically associates with the entomoparasitic nematode Steinernema carpocapsae, was studied to determine its physiological parameters of glucose utilization. X. nematophila was cultured in chemically defined media containing various concentrations of glucose under optimal conditions utilizing a two-liter fermentation system. Specific growth rates were obtained from each glucose batch. Specific growth rates and their associated glucose concentrations were used to determine physiological parameters. These parameters include the bacterium's substrate utilization constant (K s) and its maximum specific growth rate (μ max). The bacteria exhibited a K s value of 2.02 mg/L suggesting that X. nematophila has a high affinity for glucose. The μ max of Xenorhabdus was determined to be 1.03 h−1. Further research is needed to determine if microbial affinities to different substrates have any influence on biological relationships (symbiosis, pathogenicity, parasitism, etc.) between prokaryotes and higher organisms.

Washing-free heterogeneous immunosensor using proximity-dependent electron mediation between an enzyme label and an electrode.

Washing processes, essential in most heterogeneous labeled assays, have been a big hurdle in simplifying the detection procedure and reducing assay time. Nevertheless, less attention has been paid to washing-free heterogeneous labeled assays. We report a purely washing-free immunosensor that allows fast, sensitive, and single-step detection of prostate-specific antigen in serum with low interference. Proximity-dependent electron mediation of ferrocenemethanol (Fc) between an indium-tin oxide (ITO) electrode and a glucose-oxidase (GOx) label allows us to discriminate between a bound and an unbound label: a bound label offers faster electron mediation than an unbound one. The electrooxidation of Fc at a low applied potential (0.13 V vs Ag/AgCl) and a low electrocatalytic ITO electrode and the oxidation of l-ascorbic acid by l-ascorbate oxidase minimize the effect of the interfering species. With a high concentration of glucose (200 mM), the signal and background levels are hardly dependent on the glucose-concentration variation in the sample. The washing-free immunosensor can detect a concentration of ca. 1 pg/mL for mouse IgG in phosphate-buffered saline and a concentration of ca. 10 pg/mL for prostate-specific antigen spiked in female serum after an incubation period of 10 min. The concentrations measured with actual clinical serum samples are in good agreement with the concentrations measured with a commercial instrument, which renders the washing-free heterogeneous immunosensor appealing for practical use.

A co culture approach show that polyamine turnover is affected during inflammation in Atlantic salmon immune and liver cells and that arginine and LPS exerts opposite effects on p38MAPK signaling

This study assess which pathways and molecular processes are affected by exposing salmon head kidney cells or liver cells to arginine supplementation above the established requirements for growth support. In addition to the conventional mono cultures of liver and head kidney cells, co cultures of the two cell types were included in the experimental set up. Responses due to elevated levels of arginine were measured during inflammatory (lipopolysaccharide/LPS) and non -inflammatory conditions. LPS up regulated the genes involved in polyamine turnover; ODC (ornithine decarboxylase), SSAT (spermidine/spermine-N1-acetyltransferase) and SAMdc (S-adenosyl methionine decarboxylase) in head kidney cells when co cultured with liver cells. Regardless of treatment, liver cells in co culture up regulated ODC and down regulated SSAT when compared to liver mono cultures. This suggests that polyamines have anti-inflammatory properties and that both salmon liver cells and immune cells seem to be involved in this process. The transcription of C/EBP β/CCAAT, increased during inflammation in all cultures except for liver mono cultures. The observed up regulation of this gene may be linked to glucose transport due to the highly variable glucose concentrations found in the cell media. PPARα transcription was also increased in liver cells when receiving signals from head kidney cells. Gene transcription of Interleukin 1β (IL-1β), Interleukin-8 (IL-8), cyclooxygenase 2 (COX2) and CD83 were elevated during LPS treatment in all the head kidney cell cultures while arginine supplementation reduced IL-1β and IL-8 transcription in liver cells co cultured with head kidney cells. This is probably connected to p38MAPK signaling as arginine seem to affect p38MAPK signaling contrary to the LPS induced p38MAPK signaling, suggesting anti-inflammatory effects of arginine/arginine metabolites. This paper shows that co culturing these two cell types reveals the connection between metabolism and inflammation, suggesting different pathways and candidate biomarkers to be further explored.

1,10-Phenanthroline-5,6-dione and 9,10-phenanthrenequinone as redox mediators for amperometric glucose biosensors

In this study, two ortho-quinoidal compounds, 1,10-phenanthroline-5,6-dione (PD) and 9,10-phenanthrenequinone (PQ), were examined as electron transfer mediators suitable for amperometric glucose biosensors. The dependences of the electrochemical responses of PD- and PQ-based amperometric glucose biosensors on varied concentrations of glucose were investigated under aerobic and anaerobic conditions. The PD-modified graphite rod (GR) electrode revealed a current response seven times higher than that of the PQ-modified GR electrode. The reactivity indices of ortho-quinoidals assessed by means of B3LYP functional method applying 6-311G(D) basis set showed that the electron-accepting potency for PD was markedly higher as compared with that of PQ. Compared to PQ, considerably higher reactivity of PD has been defined in the reactions with NADP+-ferredoxin reductase (FNR, EC 1.18.1.2) as a model single-electron transfer FAD-dependent enzyme, which provided an additional evidence for PD as a more efficient mediator compared to PQ. This study illustrates that PD can be applied as a redox mediator for glucose oxidase and it could be more suitable for a reagent-less biosensor design than PQ.

Extracellular pH, lactate, and a hypothesis for NADH-associated proton dynamics in tumor cells

Event Abstract Back to Event Extracellular pH, lactate, and a hypothesis for NADH-associated proton dynamics in tumor cells Angela M. Otto1* and Cornelia Janzon2 1 Technische Universitaet Muenchen, Institute of Medical Engineering (IMETUM), Germany 2 Klinikum Leverkusen, Abteilung Onkologie/Haematologie, Germany Background and aim. The microenvironment of tumor cells is characterized by a gradual deprivation of nutrients and oxygen, an accumulation of lactate, and increased acidification. The question is how variable combinations of these components change tumor cell growth and metabolic activity in quantitative terms. The aim here is to investigate how extracellular lactate and pH affect this metabolic activity under limiting nutrient conditions. Methods. The breast cancer cell line MCF-7 was cultivated in “low growth” medium (DMEM with reduced FCS, containing tumor-relevant concentrations of glucose, glutamine as well as lactate, and set at different pH (6.6 – 7.4) for up to 4 days. Growth was determined by cell count. The WST-assay was used as a measure of plasma membrane NADH-oxidase activity (1). The activities of pyruvate kinase and lactate dehydrogenase (LDH) in cell lysates were measured by the kinetics of NADH-based changes in absorption. Lactate production was determined in cell culture supernatants using LDH activity as a read out. Results. At pH 7.4 with combinations of variable glucose concentrations and 0.1 mM glutamine, tumor cell growth was low, but the activity of NADH oxidase activity markedly increased at 2.5. mM glucose. Pyruvate kinase activity was also increased, while LDH activity remained 2-3-fold lower than that of pyruvate kinase. The inhibition of mitochondrial respiration by rotenone transiently increased NADH oxidase activity further. Lactate (25 mM) further increased NADH oxidase activity, but enhanced growth only at limiting conditions. At an acidic pH (6.6), these tumor cells become virtually independent of glucose and glutamine levels for both growth and the metabolic parameters tested. The culture medium of such cells contained only 7% of the lactic acid measured for cultures at pH 7.4, suggesting attenuated lactate release. Conclusions / Discussion. Extracellular pH has a differential effect on the replenishment of NAD+ from NADH produced by glycolysis. This is not solely accomplished by LDH, but may also involve plasma membrane NADH oxidase activity. Furthermore, lactate may be converted to pyruvate and support the TCA-cycle, thereby enhancing mitochondrial NADH levels. The resistance of NADH oxidase activity to rotenone suggests that reduction equivalents, along with the respective protons, are shuttled from the mitochondria to the cytosol. A hypothesis is proposed to explain the changes in plasma membrane NADH oxidase activity with respect to glycolysis and the tricarbonic acid cycle. Acknowledgements Part of this work was supported by the German Research Council (DFG). References (1) Berridge, M.V. and Tan, A.S. (1998) Trans-plasma membrane electron transport: A cellular assay for NADH- and NADPH-oxidase based on extracellular, superoxide-mediated reduction of the sulfonated tetrazolium salt WST-1. Protoplasma, 205:74-82. Keywords: Tumor Cells, Cultured, nutrient deprivation, Glucose, Glutamine, extracellular pH, tumor cell metabolism, Pyruvate Kinase, Lactate Dehydrogenases, extracellular lactate, NADH-oxidase, cell growth analysis Conference: 4th Annual Meeting of the International Society of Proton Dynamics in Cancer, Garching, Germany, 10 Oct - 12 Oct, 2013. Presentation Type: Abstract Topic: 4. pH and energy metabolism Citation: Otto AM and Janzon C (2014). Extracellular pH, lactate, and a hypothesis for NADH-associated proton dynamics in tumor cells. Front. Pharmacol. Conference Abstract: 4th Annual Meeting of the International Society of Proton Dynamics in Cancer. doi: 10.3389/conf.fphar.2014.61.00031 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 Dec 2013; Published Online: 07 Feb 2014. * Correspondence: Dr. Angela M Otto, Technische Universitaet Muenchen, Institute of Medical Engineering (IMETUM), Garching, 85748, Germany, otto@tum.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Angela M Otto Cornelia Janzon Google Angela M Otto Cornelia Janzon Google Scholar Angela M Otto Cornelia Janzon PubMed Angela M Otto Cornelia Janzon Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Cytotoxicity study on SH-SY5Y cells cultured at high glucose levels and treated with bupivacaine

The aim of this study was to investigate susceptibility to the neurotoxicity of local anesthetic agents in a model of gestational diabetes mellitus (GDM). SH-SY5Y cells were cultured at different concentrations of glucose and subsequently treated with 1 mmol/l bupivacaine for 6 h. Reactive oxygen species (ROS) production and apoptosis were assessed using flow cytometry in each group of cells. The MTT method was utilized to detect cell survival, and western blot analysis was used to examine changes in 78 kDa glucose‑regulated protein (GRP78) levels in neuronal cells. In all groups, levels of ROS production, cell survival and GRP78 expression were significantly different (P<0.01) following the addition of various concentrations of glucose and bupivacaine, as well as for the interaction between different concentrations of the anesthetic agents, demonstrating a statistically significant difference. In conclusion, the susceptibility of SH-SY5Y cells to the neurotoxicity of local anesthetic agents was enhanced in a model of GDM.

Noninvasive glucose measurement by fluorescence quenching of non toxic gold nanoparticles

Effects of interaction of human body compatible gold nanoparticles with glucose on fluorescence emission spectra of the nanoparticles are investigated experimentally. It is observed that nanoparticles’ fluorescence peak quenches and blue shifted because of such interaction. This procedure is sensitive even to low difference of glucose concentration. The results suggest that glucose could seriously affect the optical properties of gold nanoparticles. Furthermore, a linear range of relative shift of different fluorescence spectrum's peaks is obtained. Furthermore, comparison of fluorescence and absorption results shows that the former technique is as much as 20 times more sensitive to the variation of glucose concentration.

Differential affects of low glucose on the macroheterogeneity and microheterogeneity of glycosylation in CHO-EG2 camelid monoclonal antibodies

Background The demand for high yield recombinant protein production systems has focused industry on culture media and feed strategies that optimize productivity, yet maintain product quality attributes such as glycosylation. Minimizing media components such as glucose, reduces the production of lactate, but may also affect glycosylation. The first steps in the glycosylation pathway involve the synthesis of lipid-linked oligosaccharides (LLOs). Glycan macroheterogeneity is introduced by variation in site-specific glycosylation with the transfer of the oligosaccharide to the protein. Further modification of the oligosaccharide can occur through processing reactions, where some sugars are removed and additional sugars added. This produces microheterogeneity of the glycan pool. Both macroheterogeneity and microheterogeneity may be affected by fermentation conditions. The objective of this study has been to investigate the effect of variable concentrations of glucose on the glycosylation patterns of a camelid monoclonal antibody produced in Chinese hamster ovary (CHO) cells and to further evaluate their effect on components of the N-glycosylation pathway.

Cryopreservation of rainbow trout semen using a glucose-methanol extender

The goal of this study was to improve post-thaw quality of cryopreserved rainbow trout semen. Quality was assessed by measuring sperm motility and fertilization rates at the eyed, hatching, and swim-up larvae stages. We first tested how varying glucose concentrations in a methanol extender (0.1, 0.2, and 0.3 M, n = 9 different males per concentration) and different semen-extender ratios (1:3, 1:1, and 3:1, n = 3 males and in a separate experiment 1:3 and 1:5, n = 6) affected post-thaw motility. Sperm motility and fertilization rates of samples with 0.18 M glucose in 9% methanol as an extender, a 1:5 sperm-to-extender ratio, and a 15 min equilibration period then were measured at sperm-to-egg ratios of 100,000, 300,000, and 600,000:1. The optimal cryopreservation conditions were found to be 0.15 M glucose in the extender, a 15 min equilibration period, and a 1:5 semen-to-extender ratio. This combination resulted in high post-thaw motility (49.9%) and hatching rates (67.1 ± 18.7, 78.6 ± 17.0, and 84.4 ± 10.0% for sperm-to-egg ratios of 100,000, 300,000 and 600,000:1, respectively). To our knowledge, this is the first report to demonstrate that the post-thaw fertilization ability of rainbow trout semen can be similar to that of fresh semen at a sperm-to-egg ratio as low as 600,000:1.

A model study on effect of glucose on the basic characteristics and physical properties of natural rubber

Glucose at various concentrations was incorporated into sugar free purified natural rubber (PNR) latex to model the effect of carbohydrate on the basic characteristics and physical properties of natural rubber (NR). PNR samples treated with various concentrations of glucose were characterized for the basic properties of unvulcanized NR, i.e., gel content, molecular weight distribution and Mooney viscosity to evaluate the effect of sugar on these parameters. In addition, the effect of glucose on the physical properties of vulcanizates derived using sulfur and peroxide vulcanization was investigated. Glucose was shown to affect the viscosity of unvulcanized NR and the discoloration of vulcanized NR. Moreover, glucose was found to have a strong effect on crosslink density, as well as tensile and dynamic properties of sulfur vulcanizates, while those properties of peroxide vulcanizates was not much affected by glucose.

Elevated cell proliferation and VEGF production by high-glucose conditions in Müller cells involve XIAP.

Müller cells have important roles in the pathogenesis of diabetic retinopathy by promoting cell proliferation and inducing the production of vascular endothelial growth factor (VEGF) under hyperglycemic conditions. The objective of this study was to determine the potential mechanism of Müller cell proliferation and VEGF production due to high-glucose conditions. Primary cultured rat Müller cells were incubated with medium containing variable concentrations of glucose and/or embelin, a specific inhibitor of X-linked inhibitor of apoptosis protein (XIAP), for 72 h. The proliferation of Müller cells was assessed by the MTT assay. The expression and/or phosphorylation of 146 proteins were assessed using protein pathway array. High concentrations of glucose-induced Müller cell proliferation and altered expression and/or phosphorylation of 47 proteins that have been identified to have key roles in several important signaling pathways (XIAP, VEGF, HIF1α, NFκB, etc) and are involved in the regulation of cell survival, proliferation, or apoptosis. However, Müller cell alterations induced by high-glucose conditions were counteracted by the XIAP inhibitor embelin, and 26 proteins/phosphorylations (out of 47) were restored to their normal levels. Nine proteins, including NFκB p65, p-p38, tumor necrosis factor-α, urokinase-type plasminogen activator, CREB, IL-1β, HCAM, estrogen receptor-α, and p-Stat3, were involved in regulatory networks between XIAP and VEGF. The current study suggests that XIAP may be a potential regulator that can mediate a series of pathological changes induced by high-glucose conditions in Müller cells. Therefore, embelin could be a potential agent for the prevention and treatment of diabetic retinopathy.

Variability of Selected Biochemical Parameters in Young Stallions During the 100-day Performance Test

The aim of the study was to evaluate variations in biochemical blood parameters of stallions during a 100-day performance test. The study was carried out with 20 clinically healthy stallions aged 3-4 years. The degree of adaptation to exercise loads during a 100-day performance test was assessed three times: (I) on the first day of training, (II) on the 46th day of training, and (III) on the 97th day of training. Sample collection and basic clinical tests were performed before training (1), directly after training (2), and after a 30-minute rest (3). Venous blood samples were analyzed for the concentration of total protein, glucose (GLU), and lactate, the activity of lactate dehydrogenase (LDH), and creatine kinase (CK), and total antioxidant status (TAS). Postexercise changes in the analyzed parameters showed that the loads were of moderate intensity. As a result of the 100-day training, postexercise variation in GLU concentration and CK and LDH activity was lower than at the beginning, which indicates that the body was stimulated to adapt to performing exercise tasks. The resting level of TAS was also found to increase. The results obtained suggest that the stallions are well prepared for increasing exercise loads.

Effects of glucose availability on expression of the key genes involved in synthesis of milk fat, lactose and glucose metabolism in bovine mammary epithelial cells.

As the main precursor for lactose synthesis, large amounts of glucose are required by lactating dairy cows. Milk yield greatly depends on mammary lactose synthesis due to its osmoregulatory property for mammary uptake of water. Thus, glucose availability to the mammary gland could be a potential regulator of milk production. In the present study, the effect of glucose availability on expression of the key genes involved in synthesis of milk fat, lactose and glucose metabolism in vitro was investigated. Bovine mammary epithelial cells (BMEC) were treated for 12 h with various concentrations of glucose (2.5, 5, 10 or 20 mmol/L). The higher concentrations of glucose (10–20 mmol/L) did not affect the mRNA expression of acetyl-CoA carboxylase, diacyl glycerol acyl transferase, glycerol-3 phosphate acyl transferase and α-lactalbumin, whereas fatty acid synthase, sterol regulatory element binding protein-1 and beta-1, 4-galactosyl transferase mRNA expression increased at 10 mmol/L and then decreased at 20 mmol/L. The content of lactose synthase increased with increasing concentration of glucose, with addition of highest value at 20 mmol/L of glucose. Moreover, the increased glucose concentration stimulated the activities of pyruvate kinase and glucose-6-phosphate dehydrogenase, and elevated the energy status of the BMEC. Therefore, it was deduced that after increasing glucose availability, the extra absorbed glucose was partitioned to entering the synthesis of milk fat and lactose by the regulation of the mRNA expression of key genes, promoting glucose metabolism by glycolysis and pentose phosphate pathway as well as energy status. These results indicated that the sufficient availability of glucose in BMEC may promote glucose metabolism, and affect the synthesis of milk composition.

Isothermic determination of aqueous solution glucose concentration in low mg/dL range by CW-photoacoustic-based protocol

In order to decrease the impact of diabetes mellitus on patient quality of life, noninvasive and continuous monitoring of blood glucose level represents the ideal detection protocol for an appropriate decision-making process. The limit of detection of such a sensor should be lower than 70mg/dL for efficient detection of hypoglycemia episodes. However, a reasonable anticipation of loss of accuracy when moving from in vitro to in vivo requires demonstration of sensitivity several times lower than this value in the ideal in vitro conditions for any viable alternative to the standard finger-prick-based method. This paper then investigates the detection of aqueous glucose solutions at low concentration levels based on a measurement protocol called “frequency shift” (FS). This protocol, based on the continuous-wave photoacoustic technique, is equivalent to an acoustic velocity measurement and therefore depends on the temperature as well. A thermo-regulated bath system was then used to control the temperature with an accuracy of ±0.035°C. The sensor showed a linear glucose dependence characterized by a slope of 0.19%/g/dL, which is consistent with previously reported results, and accuracy of about ±26mg/dL was obtained. Using a differential experimental protocol, we were able to improve the temperature control accuracy down to ±0.015°C. Measurements down to a 9.6mg/dL concentration level were demonstrated with an accuracy of ±3.5mg/dL despite a bias from temperature fluctuations equivalent to a ±11mg/dL glucose concentration variation. The FS protocol then enables low milligram per deciliter glucose concentration measurements at levels several times lower than the requirements. However, temperature variations strongly limit the measurement accuracy due to the lack of FS selectivity to glucose. To take full advantage of the proposed approach, temperature should then be monitored simultaneously and its effect compensated to allow comparable sensitivity in in vivo conditions.

Glucose sensitivity of mouse olfactory bulb neurons is conveyed by a voltage‐gated potassium channel

The olfactory bulb has recently been proposed to serve as a metabolic sensor of internal chemistry, particularly that modified by metabolism. Because the voltage-dependent potassium channel Kv1.3 regulates a large proportion of the outward current in olfactory bulb neurons and gene-targeted deletion of the protein produces a phenotype of resistance to diet-induced obesity in mice, we hypothesized that this channel may play a role in translating energy availability into a metabolic signal. Here we explored the ability of extracellular glucose concentration to modify evoked excitability of the mitral neurons that principally regulate olfactory coding and processing of olfactory information. Using voltage-clamp electrophysiology of heterologously expressed Kv1.3 channels in HEK 293 cells, we found that Kv1.3 macroscopic currents responded to metabolically active (d-) rather than inactive (l-) glucose with a response profile that followed a bell-shaped curve. Olfactory bulb slices stimulated with varying glucose concentrations showed glucose-dependent mitral cell excitability as evaluated by current-clamp electrophysiology. While glucose could be either excitatory or inhibitory, the majority of the sampled neurons displayed a decreased firing frequency in response to elevated glucose concentration that was linked to increased latency to first spike and decreased action potential cluster length. Unlike modulation attributed to phosphorylation, glucose modulation of mitral cells was rapid, less than one minute, and was reversible within the time course of a patch recording. Moreover, we report that modulation targets properties of spike firing rather than action potential shape, involves synaptic activity of glutamate or GABA signalling circuits, and is dependent upon Kv1.3 expression. Given the rising incidence of metabolic disorders attributed to weight gain, changes in neuronal excitability in brain regions regulating sensory perception of food are of consequence.

High glucose induces apoptosis and suppresses proliferation of adult rat neural stem cells following in vitro ischemia

BackgroundPost-stroke hyperglycemia appears to be associated with poor outcome from stroke, greater mortality, and reduced functional recovery. Focal cerebral ischemia data support that neural stem cells (NSCs) play an important role in post-ischemic repair. Here we sought to evaluate the negative effects of hyperglycemia on the cellular biology of NSCs following anoxia, and to test whether high glucose affects NSC recovery from ischemic injury.ResultsIn this study, we used immortalized adult neural stem cells lines and we induced in vitro ischemia by 6 h oxygen and glucose deprivation (OGD) in an anaerobic incubator. Reperfusion was performed by returning cells to normoxic conditions and the cells were then incubated in experimental medium with various concentrations of glucose (17.5, 27.75, 41.75, and 83.75 mM) for 24 h. We found that high glucose (≥27.75 mM) exposure induced apoptosis of NSCs in a dose-dependent manner after exposure to OGD, using an Annexin V/PI apoptosis detection kit. The cell viability and proliferative activity of NSCs following OGD in vitro, evaluated with both a Cell Counting kit-8 (CCK-8) assay and a 5-ethynyl-2’-deoxyuridine (EdU) incorporation assay, were inhibited by high glucose exposure. Cell cycle analysis showed that high glucose exposure increased the percentage of cells in G0/G1-phase, and reduced the percentage of cells in S-phase. Furthermore, high glucose exposure was found to significantly induce the activation of c-Jun N-terminal protein kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) and suppress extracellular signal-regulated kinase 1/2 (ERK1/2) activity.ConclusionsOur results demonstrate that high glucose induces apoptosis and inhibits proliferation of NSCs following OGD in vitro, which may be associated with the activation of JNK/p38 MAPK pathways and the delay of G1-S transition in the cells.

Microcalorimetric study of growth of Lactococcus lactis IL1403 at low glucose concentration in liquids and solid agar gels

Growth of Lactococcus lactis IL1403 in liquid cultures and solid agar gels at different low glucose concentrations starting from 2gL−1 up to 10gL−1 with a stepwise increase by 1gL−1 was studied using thermal activity monitor TAM III. In parallel to calorimetric measurements the changes of glucose and lactic acid concentrations and pH of culture media were measured in order to obtain additional information for the interpretation of calorimetric power–time curves. The data obtained together with calculated heat yield coefficient YQ allowed to analyze the growth of bacteria in colonies in solid agar gels in detail. The variation of glucose concentration at low levels allows analyzing and describing growth deceleration phase and growth stopping mechanisms both in liquid cultures and in solid-state fermentations.

Optimal Formation of Genetically Modified and Functional Pancreatic Islet Spheroids by Using Hanging-Drop Strategy

BackgroundRejection and hypoxia are important factors causing islet loss at an early stage after pancreatic islet transplantation. Recently, islets have been dissociated into single cells for reaggregation into so-called islet spheroids. Herein, we used a hanging-drop strategy to form islet spheroids to achieve functional equivalence to intact islets. MethodsTo obtain single islet cells, we dissociated islets with trypsin-EDTA digestion for 10 minutes. To obtain spheroids, we dropped various numbers of single cells (125, 250, or 500 cells/30 μL drop) onto a Petri dish, that was inverted for incubation in humidified air containing 5% CO2 at 37°C for 7 days. The aggregated spheroids in the droplets were harvested for further culture. ResultsThe size of the aggregated islet spheroids depended on the number of single cells (125–500 cells/30 μL droplet). Their morphology was similar to that of intact islets without any cellular damage. When treated with various concentrations of glucose to evaluate responsiveness, their glucose-mediated stimulation index value was similar to that of intact islets, an observation that was attributed to strong cell-to-cell interactions in islet spheroids. However, islet spheroids aggregated in general culture dishes showed abnormal glucose responsiveness owing to weak cell-to-cell interactions. Cell-to-cell interactions in islet spheroids were confirmed with an anti–connexin-36 monoclonal antibody. Finally, nonviral poly(ethylene imine)–mediated interleukin-10 cytokine gene delivered beforehand into dissociated single cells before formation of islet spheroids increased the gene transfection efficacy and interleukin-10 secretion from islet spheroids >4-fold compared with intact islets. ConclusionThese results demonstrated the potential application of genetically modified, functional islet spheroids with of controlled size and morphology using an hanging-drop technique.