Glucose Concentration-dependent Manner Research Articles

GABA-mediated inhibition of human CD4+ T cell functions is enhanced by insulin but impaired by high glucose levels

γ-aminobutyric acid (GABA), known as the main inhibitory neurotransmitter in the brain, exerts immunomodulatory functions by interaction with immune cells, including T cells. Metabolic programs of T cells are closely linked to their effector functions including proliferation, differentiation, and cytokine production. The physiological molecules glucose and insulin may provide environmental cues and guidance, but whether they coordinateto regulate GABA-mediated T cell immunomodulation is still being examined. CD4+ T cells that were isolated from blood samples from healthy individuals and from patients with type 1 diabetes (T1D) were activated invitro. We carried out metabolic assays, multiple proximity extension assay (PEA), ELISA, qPCR, immunoblotting, immunofluorescence staining, flow cytometry analysis, MS-based proteomics, as well as electrophysiology and live-cell Ca2+ imaging. We demonstrate that GABA-mediated reduction of metabolic activity and the release of inflammatory proteins, including IFNγ and IL-10, were abolished in human CD4+ T cells from healthy individuals and patients with T1D when the glucose concentration was elevated above levels typically observed in healthy people. Insulin increased GABAA receptor-subunit ρ2 expression, enhanced the GABAA receptors-mediated currents and Ca2+ influx. GABA decreased, whereas insulin sustained, hexokinase activity and glycolysis in a glucose concentration-dependent manner. These findings support that metabolic factors, such as glucose and insulin, influence the GABA-mediated immunomodulation of human primary T cells effector functions. The Swedish Children's Diabetes Foundation, The Swedish Diabetes Foundation, The Swedish Research Council 2018-02952, EXODIAB, The Ernfors Foundation, The Thurings Foundation and the Science for Life Laboratory.

Verifying the Safety of Microbial Contamination in Self-Injectors of Glucagon-like peptide-1 Receptor Agonists

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) enhance insulin secretion in patients with type 2 diabetes mellitus in a glucose concentration-dependent manner. Many GLP-1RA formulations are administered in divided doses using a needle attached to the patient. Prior to use, the formulation is store in a cool place owing to stability. However, it is store at room temperature after use owing to problems with the injector. Therefore, the split-dose GLP-1RAs formulations contain phenolic antiseptics (phenol and cresol). Contamination of the formulation with microorganisms must be considered because patient self-injection is not performed under aseptic conditions. Therefore, this study verified the safety against microbial contamination during use based on Escherichia coli survival in split-dose GLP-1RA formulations. Unused liraglutide, exenatide, and lixisenatide were contaminated with E. coli stored at 25°C (room temperature) and cultured over time. E. coli gradually decreased immediately after suspension and E. coli did not survive after 60-90 min. The preservative of the split-dose GLP-1RAs formulation exhibited sufficient sterilizing power at 25°C, and it was inferred that room temperature is preferable for storage after use considering the formulation storage conditions, including injector failure and drug denaturation.

Tumor-targeted glycogen nanoparticles loaded with hemin and glucose oxidase to promote tumor synergistic therapy

Strategies which are used to address the low levels of intracellular hydrogen peroxide and the development of biocompatible catalysts still need to be fulfilled in tumor chemodynamic therapy. Therefore, a novel tumor-targeted glycogen-based nanoparticle system (GN/He/GOx/HA) was developed to co-deliver hemin (He) and GOx, which can self-supply glucose formed upon degradation of glycogen by α-glycosidase in the lysosome environment, in order to achieve synergistic antitumor therapy. Hyaluronic acid (HA) was selected as the outer shell to protect the activity of GOx, and to increase the uptake by tumor cells via CD44 receptor-mediated endocytosis. GN/He/GOx/HA NPs had a good stability in the blood circulation, but fast release of the therapeutic cargos upon intracellular uptake. Hemin had a cascade catalytic reaction with GOx. Furthermore, GN/He/GOx/HA NPs had the strongest cytotoxicity in Hela cells in a glucose concentration dependent manner. The NPs could efficiently produce reactive oxygen species in tumor cells, resulting in a decrease in the mitochondrial membrane potential and apoptosis of tumor cells. The in vivo results showed that the drug-loaded nanoparticles had good safety, biocompatibility, and efficacious antitumor effect. Therefore, the glycogen-based nanoparticle delivery system provides potential application for self-enhancing CDT, which can be used for effective antitumor therapy.

The peroxidase-like activity of papain colorimetrically detects H2O2 and glucose with high sensitivity

To date, several glucometer methods are available for patient-guided glycemic control, which diminishes the onset and severity of diabetic complications. In a dipstick urine glucose test, horseradish peroxidase (HRP) oxidizes tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) to quantitatively produce a colorimetric signal and predict glucose concentration. Papain, a sulfhydryl protease secreted by the latex of Carica papaya, displays HRP-like activity with high selectivity. However, the current papain-based glucometer method lacks sensitivity. We hypothesized that catalyzing the oxidation of papain under varying buffer conditions (e.g., papain, TMB, and acetic acid concentrations) would improve glucose detection sensitivity. To test this, we performed glucose oxidase (GOx)-mediated glucose oxidation and papain-mediated TMB oxidation under varying sample conditions in vitro and spontaneously coupled them. The aims of this study were to validate the coupling of GOx-mediated glucose oxidation and papain-mediated TMB oxidation and identify the optimized conditions that maximize catalytic activity. We confirmed that glucose oxidase quantitatively produces H2O2 (in a glucose concentration-dependent manner), the presence of which catalyzes papain-mediated production of a colorimetric signal. When two oxidation reactions were coupled, we identified that the sensitivity of papain’s glucose detection increased by ten-fold compared to previous studies with a markedly high correlation (R2 = 0.99). In particular, substituting sodium acetate-acetic acid (HAc-NaAc) buffer with acetic acid and increasing the sample incubation time and papain concentration markedly increased the sensitivity of colorimetric signals. The optimized protocols can be integrated into emerging hydrogel technology to develop a non-invasive glucometer patch predicting blood glucose from the patient’s produced sweat.

The extracellular matrix of human bone marrow adipocytes and glucose concentration differentially alter mineralization quality without impairing osteoblastogenesis

Bone marrow adipocytes (BMAds) accrue in various states of osteoporosis and interfere with bone remodeling through the secretion of various factors. However, involvement of the extracellular matrix (ECM) produced by BMAds in the impairment of bone marrow mesenchymal stromal cell (BM-MSC) osteoblastogenesis has received little attention. In type 2 diabetes (T2D), skeletal fragility is associated with several changes in bone quality that are incompletely understood, and BMAd quantity increases in relationship to poor glycemic control. Considering their altered phenotype in this pathophysiological context, we aimed to determine the contribution of the ECM of mature BMAds to osteoblastogenesis and mineralization quality in the context of chronic hyperglycemia.Human BM-MSCs were differentiated for 21 days in adipogenic medium containing either a normoglycemic (LG, 5.5 mM) or a high glucose concentration (HG, 25 mM). The ECM laid down by BMAds were devitalized through cell removal to examine their impact on the proliferation and differentiation of BM-MSCs toward osteoblastogenesis in LG and HG conditions. Compared to control plates, both adipocyte ECMs promoted cell adhesion and proliferation. As shown by the unmodified RUNX2 and osteocalcin mRNA levels, BM-MSC commitment in osteoblastogenesis was hampered by neither the hyperglycemic condition nor the adipocyte matrices. However, adipocyte ECMs or HG condition altered the mineralization phase with perturbed expression levels of type 1 collagen, MGP and osteopontin. Despite higher ALP activity, mineralization levels per cell were decreased for osteoblasts grown on adipocyte ECMs compared to controls. Raman spectrometry revealed that culturing on adipocyte matrices specifically prevents type-B carbonate substitution and favors collagen crosslinking, in contrast to exposure to HG concentration alone. Moreover, the mineral to organic ratio was disrupted according to the presence of adipocyte ECM and the glucose concentration used for adipocyte or osteoblast culture. HG concentration and adipocyte ECM lead to different defects in mineralization quality, recapitulating contradictory changes reported in T2D osteoporosis.Our study shows that ECMs from BMAds do not impair osteoblastogenesis but alter both the quantity and quality of mineralization partly in a glucose concentration-dependent manner. This finding sheds light on the involvement of BMAds, which should be considered in the compromised bone quality of T2D and osteoporosis patients more generally.

P-104 production and glucose-dependent secretion of insulin by human spermatozoa

Abstract Study question Do human spermatozoa express insulin and the enzymes responsible for the cleavage of proinsulin? Is the secretion of insulin by spermatozoa responsive to glucose stimuli? Summary answer Human spermatozoa express insulin and PC1/3 and PC2, enzymes responsible for the cleavage of proinsulin. Spermatozoa produce and release insulin in a glucose concentration-dependent manner. What is known already Spermatogenesis is dependent on a finely regulated hormonal and metabolic control. Insulin is considered one of the most important regulators in the metabolic regulation of spermatogenesis, acting directly on the differentiation of spermatogonia into primary spermatocytes or indirectly through the metabolic modulation of both Sertoli and Leydig cells. In addition, insulin is hypothesized to play a major role in human spermatozoa capacitation, although the mechanisms that regulate its production and secretion remain to be disclosed. Study design, size, duration The main objective of this study was to estimate the capacity of insulin production by human spermatozoa and if they express PC1/3 and PC2, which are enzymes responsible for the cleavage of proinsulin. In addition, we hypothesized that insulin production could respond to glucose stimuli. Seminal samples of normozoospermic men (n = 15) seeking fertility treatment were collected for these experiments. Participants/materials, setting, methods Spermatozoa were submitted to a density gradient centrifugation and two fractions were collected according to their motility (high vs low motility). The expression of insulin, PC1/3 and PC2 mRNA was evaluated by RT-qPCR. The protein expression of insulin, PC1/3 and PC2 was evaluated by immunofluorescence. High motility spermatozoa were incubated in BWW medium with increasing glucose concentrations (0, 5.5, 11, and 22 mM). After 6 h, the concentration of secreted insulin was quantified by ELISA. Main results and the role of chance We were able to identify the expression of insulin, PC1/3, and PC2 mRNA, as well as the respective proteins, in human spermatozoa. Through immunofluorescence, we observed that insulin and both enzymes are mainly expressed in the midpiece. Human spermatozoa also express insulin receptor, mainly in the midpiece and tail. The mRNA expression of insulin and PC1/3 was found to be higher in the highly motile spermatozoa. Human spermatozoa produce very small quantities of insulin (pg/mL range), which suggests an autocrine or paracrine action. The release of insulin to the medium was found to occur in a glucose concentration-dependent manner. Limitations, reasons for caution This is an in vitro study with relatively small sample size. Future studies are required to further evaluate the role of insulin and its signalling pathway on human spermatozoa capacitation and fertilization capacity. Wider implications of the findings This study shows that human spermatozoa express PC1/3 and PC2, enzymes responsible for the cleavage of proinsulin. In addition, human spermatozoa release insulin in a glucose concentration-dependent manner. The study of insulin signalling opens the path for a deeper understanding of human spermatozoa bioenergetics and the development of novel therapies. Trial registration number Not applicable

CTRP7 Is a Biomarker Related to Insulin Resistance and Oxidative Stress: Cross-Sectional and Intervention Studies In Vivo and In Vitro.

Objective CTRP7 is a cytokine that is known to be associated with obesity. However, its relationship with insulin resistance (IR) and metabolic diseases remains unknown. The aim of this study is to investigate the relationship between CTRP7 and IR under in vivo and in vitro conditions. Methods CTRP7 expression in mice and hepatocytes was determined using RT-qPCR and western blotting. Circulating CTRP7 concentrations were measured with an ELISA kit. EHC, OGTT, lipid-infusion, physical activity, and cold-stimulation experiments were performed in humans and mice. SOD, GSH, and MDA were measured by commercial kits. ROS levels were detected using dichlorofluorescein diacetate. Results The expression levels of CTRP7 protein in the liver and fat of ob/ob and db/db mice were higher than that of WT mice. Individuals with IGT, T2DM, and obesity had higher circulating CTRP7 levels. CTRP7 levels were associated with HOMA-IR, obesity, and other metabolic parameters. During OGTT, serum CTRP7 levels gradually decreased, while CTRP7 levels significantly increased during EHC in response to hyperinsulinemia in healthy individuals without IR. In addition, lipid infusion-induced IR further increased serum CTRP7 levels in healthy adults. Physical activity increased serum CTRP7 levels in healthy individuals and CTRP7 protein expression in iWAT and skeletal muscle in mice. Under in vitro conditions, the expression of the CTRP7 protein was inhibited in a glucose concentration-dependent manner but was promoted by FFAs and insulin stimulation in hepatocytes. Furthermore, CTRP7 overexpression facilitated oxidative stress and suppressed the phosphorylation of insulin signaling molecules in hepatocytes. Conclusions Our evidence shows that CTRP7 could be a useful biomarker and potential treatment target in IR and metabolic disorders.

Scopoletin stimulates the secretion of insulin via a KATP channel-dependent pathway in INS-1 pancreatic β cells.

In this study, we investigated whether scopoletin stimulated the secretion of insulin in pancreatic β cells as well as the underlying mechanism involved in this process. We incubated the INS-1 pancreatic β cells with various concentrations of glucose (1.1, 5.6 or 16.7 mM) in the presence or absence of scopoletin. We then analysed the secretion of insulin in the cells treated with insulin secretion inhibitors or secretagogues. The intracellular influx of calcium induced by scopoletin was also analysed using the Fluo-2 AM dye. We found that scopoletin (1-20 µM) markedly induced the secretion of insulin in a glucose concentration-dependent manner compared with the control. At depolarizing concentrations of potassium chloride (KCl), scopoletin markedly enhanced the insulin secretion compared with the cells which were treated only with KCl. Moreover, the treatment with diazoxide-opening K+ATP channel and verapamil blocking Ca2+ channel significantly decreased the scopoletin-induced increase in insulin secretion. After the pre-treatment of cells with a Ca2+ fluorescent dye, treatment with 20 µM scopoletin resulted in a significant increase in the influx of intracellular Ca2+, exhibiting fluorescence changes in various spectra. Scopoletin stimulates the secretion of insulin via a K+ATP channel-dependent pathway in the INS-1 pancreatic β cells.

New drug for type 2 diabetes: introduction of oral Semaglutide (Rybelsus® tablets), an oral GLP-1 receptor agonist

GLP-1 (glucagon-like peptide-1) is one of the incretin hormone secreted from L cells in the small intestine and it is known to promote insulin secretion in a glucose concentration-dependent manner and have a hypoglycemic effect. However, since endogenous GLP-1 is rapidly degraded by ubiquitously expressing DPP-4, a GLP-1 receptor agonist with a longer half-life has been required. Semaglutide is a GLP-1 analog that has 94% homology with human GLP-1 and it binds to the GLP-1 receptor in pancreatic β-cells to induce the insulin secretion in a glucose concentration-dependent manner. Semaglutide has a high affinity for the fatty acid binding site of albumin and has an extended half-life by being protected from degradation by DPP-4, due to specific modification of its amino acid sequence. A once weekly semaglutide (Ozempic® Subcutaneous Injection 2 mg) is used worldwide as a treatment for type 2 diabetes when diet and exercise therapy are inadequate. In Japan, it was approved for manufacturing and marketing in March 2018. Oral semaglutide (Rybelsus®) has been co-formulated with the absorption enhancer sodium N-(8-[2-hydroxybenzoyl]amino) caprylate (SNAC), and is the first GLP-1 receptor agonist (GLP-1RA) to be approved for oral administration. Rybelsus® have been shown to be of continuous benefit in patients with type 2 diabetes at various stages by monotherapy and combination therapy with 3, 7 and 14 mg Rybelsus in eight global clinical trials and two Japanese trials. It was suggested that oral semaglutide make patients with chronic and progressive type 2 diabetes may be able to achieve the earlier improvement in glycemic control as global diabetes association recommended.

Insulin receptor cleavage induced by estrogen impairs insulin signaling

IntroductionSoluble insulin receptor (sIR), which is the ectodomain of insulin receptor (IR), is present in human plasma. Plasma sIR levels are positively correlated with blood glucose levels and negatively correlated...

Effects of Switching from Liraglutide or Dulaglutide to Subcutaneous Semaglutide on Glucose Metabolism and Treatment Satisfaction in Patients with Type 2 Diabetes: Protocol for a Multicenter, Prospective, Randomized, Open-Label, Blinded-Endpoint, Parallel-Group Comparison Study (The SWITCH-SEMA 1 Study).

IntroductionGlucagon-like peptide (GLP)-1 receptor agonists exert potent hypoglycemic effects in patients with type 2 diabetes (T2D) in a blood glucose concentration-dependent manner. Once-weekly subcutaneous administration of the GLP-1 receptor agonist semaglutide has beneficial effects on glycemic and body weight control, but it is currently unclear if semaglutide provides superior glycemic control compared to conventional GLP-1 receptor agonists in the Japanese population. We aim to compare the effects of once-weekly subcutaneous semaglutide with those of liraglutide or dulaglutide administration in Japanese patients with T2D.MethodsThis study is a multicenter, prospective, randomized, open-label, blinded-endpoint, parallel-group trial. In total, 100 participants with T2D who have been treated with liraglutide (0.9–1.8 mg/day in plan A) or dulaglutide (0.75 mg/week in plan B) for more than 12 weeks and have a glycated hemoglobin (HbA1c) level of 6.0–9.9% and a body mass index (BMI) of ≥ 22 kg/m2 will be randomized to either continue using their existing GLP-1 receptor agonist or switch to subcutaneous semaglutide once weekly for 24 weeks. Biochemical analysis, physical assessment, and a quality-of-life questionnaire (DTSQ) will be completed at baseline and at the end of the study. The primary endpoint is the effect of semaglutide on the change in HbA1c. The secondary endpoints are the mean changes in total DTSQ score, body mass, abdominal circumference, systolic and diastolic blood pressure, pulse rate, factors associated with improvement in HbA1c and secondary endpoints, side effects, and other laboratory parameters.Planned OutcomesThe results of the study will provide useful information regarding the effects of switching to semaglutide from other GLP-1 receptor agonists on glycemic control in patients with T2D.Ethics and DisseminationThe Hokkaido University Certified Review Board (CRB no. 1180001) has approved the protocol (no. 018-005). The results will be disseminated in peer-reviewed journals and at scientific conferences.Trial RegistrationUMIN000042369 in the University Hospital Medical Information Network (UMIN); jRCT1011200008 in the Japan Registry of Clinical Trials (jRCT); pre-results.

An Aldehyde Responsive, Cleavable Linker for Glucose Responsive Insulins.

A glucose responsive insulin (GRI) that responds to changes in blood glucose concentrations has remained an elusive goal. Here we describe the development of glucose cleavable linkers based on hydrazone and thiazolidine structures. We developed linkers with low levels of spontaneous hydrolysis but increased level of hydrolysis with rising concentrations of glucose, which demonstrated their glucose responsiveness in vitro. Lipidated hydrazones and thiazolidines were conjugated to the LysB29 side-chain of HI by pH-controlled acylations providing GRIs with glucose responsiveness confirmed in vitro for thiazolidines. Clamp studies showed increased glucose infusion at hyperglycemic conditions for one GRI indicative of a true glucose response. The glucose responsive cleavable linker in these GRIs allow changes in glucose levels to drive the release of active insulin from a circulating depot. We have demonstrated an unprecedented, chemically responsive linker concept for biopharmaceuticals.

High glucose contributes to the polarization of peritoneal macrophages to the M2 phenotype invivo and invitro.

Glucose is the primary osmotic medium used in most peritoneal dialysis (PD) solutions, and long-term exposure to high glucose is a major contributor to peritoneal fibrosis. Our previous study revealed that M2 macrophages participate in the development of PD-related fibrosis in a rat model. In the present study, the effects of high glucose on peritoneal macrophage polarization in vivo and in vitro were further evaluated. Continuous ambulatory PD (CAPD) patients with an overnight dwell of 1.5 or 2.5% glucose dialysate were recruited for this study. Overnight effluent samples from patients with CAPD (2,000 ml) were centrifuged to collect cells from the peritoneal cavity. J774A.1 cells (murine macrophages from ascites) were cultured in different concentrations of glucose. Macrophage phenotype markers were detected by flow cytometry. The levels of cytokines in PD effluent and the supernatant of murine macrophages were detected by enzyme-linked immunosorbent assays. The activity of arginase was determined by quantitative colorimetric analysis. In total, 107 CAPD subjects (92 patients using 1.5% glucose dialysate and 15 patients using 2.5% glucose dialysate) were recruited. The percentage of M1 macrophages (CD14- and CCr7-positive cells) in the 1.5 and 2.5% glucose dialysate groups was 23.0±13.3 and 24.9±12.0%, respectively. The difference was not significant (P>0.05). The percentage of M2 macrophages (CD14- and CD206-positive cells) in the 1.5% glucose dialysate group (36.2±11.4%) was significantly decreased compared to the 2.5% glucose dialysate group (43.2±7.4%) (P<0.05). Murine macrophages were cultured in a high-glucose in vitro environment, and the percentage of M1 macrophages in 138.8 mmol/l glucose medium significantly increased over time. The percentage of M2 macrophages increased in a glucose concentration-dependent and time-dependent manner. Arginase 1 in murine macrophages and the level of transforming growth factor β1 in the supernatant increased in a glucose concentration-dependent manner. In conclusion, high glucose contributed to the polarization of peritoneal macrophages to the M2 phenotype, which may play an important role in the pathogenesis of PD-related fibrosis.

A genetic screen identifies Crat as a regulator of pancreatic beta-cell insulin secretion

ObjectivesGlucose-stimulated insulin secretion is a critical function in the regulation of glucose homeostasis, and its deregulation is associated with the development of type 2 diabetes. Here, we performed a genetic screen using islets isolated from the BXD panel of advanced recombinant inbred (RI) lines of mice to search for novel regulators of insulin production and secretion. MethodsPancreatic islets were isolated from 36 RI BXD lines and insulin secretion was measured following exposure to 2.8 or 16.7 mM glucose with or without exendin-4. Islets from the same RI lines were used for RNA extraction and transcript profiling. Quantitative trait loci (QTL) mapping was performed for each secretion condition and combined with transcriptome data to prioritize candidate regulatory genes within the identified QTL regions. Functional studies were performed by mRNA silencing or overexpression in MIN6B1 cells and by studying mice and islets with beta-cell-specific gene inactivation. ResultsInsulin secretion under the 16.7 mM glucose plus exendin-4 condition was mapped significantly to a chromosome 2 QTL. Within this QTL, RNA-Seq data prioritized Crat (carnitine O-acetyl transferase) as a strong candidate regulator of the insulin secretion trait. Silencing Crat expression in MIN6B1 cells reduced insulin content and insulin secretion by ∼30%. Conversely, Crat overexpression enhanced insulin content and secretion by ∼30%. When islets from mice with beta-cell-specific Crat inactivation were exposed to high glucose, they displayed a 30% reduction of insulin content as compared to control islets. We further showed that decreased Crat expression in both MIN6B1 cells and pancreatic islets reduced the oxygen consumption rate in a glucose concentration-dependent manner. ConclusionsWe identified Crat as a regulator of insulin secretion whose action is mediated by an effect on total cellular insulin content; this effect also depends on the genetic background of the RI mouse lines. These data also show that in the presence of the stimulatory conditions used the insulin secretion rate is directly related to the insulin content.

High glucose promotes annulus fibrosus cell apoptosis through activating the JNK and p38 MAPK pathways.

Diabetes mellitus (DM) is an important risk factor of intervertebral disc degeneration. A high glucose niche-mediated disc cell apoptosis is an implicate causative factor for the spine degenerative diseases related with DM. However, the effects of a high glucose niche on disc annulus fibrosus (AF) cell apoptosis and the potential signaling transduction pathway is unclear. The present study is to investigate the effects of high glucose on disc AF cell apoptosis and the role of two potential signaling pathways in this process. Rat AF cells were cultured in baseline medium or medium with different concentrations (0.1 and 0.2 M) of glucose for 3 days. Flow cytometry was used to assess the degree of apoptosis. Activity of caspase 3/9 was evaluated by chemical kit. Expression of pro-apoptotic and anti-apoptotic molecules was analyzed by real-time polymerase chain reaction and Western blot. In addition, activity of the C-Jun NH2-terminal kinases (JNK) pathway and p38 mitogen-activated protein kinase (MAPK) pathway was evaluated by Western blot. Compared with the control group, high glucose culture increased cell apoptosis ratio and caspase-3/9 activity, up-regulated expression of bax, caspase-3, cleaved caspase-3 and cleaved PARP, and down-regulated expression of bcl-2 in a glucose concentration-dependent manner. Additionally, high glucose culture increased expression of the p-JNK and p-p38 MAPK in a concentration-dependent manner. Further results showed that inhibition of the JNK or p38 MAPK pathway attenuated the effects of high glucose on AF cell apoptosis. Together, high glucose promoted disc AF cell apoptosis through regulating the JNK pathway and p38 MAPK pathway in a glucose concentration-dependent manner.

Metabolic shift of Staphylococcus aureus under sublethal dose of methicillin in the presence of glucose

Traditional strategies in developing novel drugs to treat antibiotic-resistant S. aureus have not been very successful to date, therefore, there is an urgent need for creative usage of existing agents that can treat and control S. aureus infection. This study demonstrated that a combination of glucose and a sublethal dose of antibiotic can reduce the survivability of S. aureus in a glucose concentration-dependent manner. Mass spectrometry-based targeted metabolic profiling detected massive metabolic profile shift of both methicillin-susceptible and resistant S. aureus after methicillin and glucose co-treatment. The dramatic alteration of metabolites from these metabolic pathways can be detected when 10 mg/L or higher concentration of glucose were added to methicillin treated culture. Our data also indicated that multiple biochemical metabolic pathways, including pyrimidine metabolism and valine, leucine, and isoleucine degradation showed a significant difference (p < 0.01) in comparison of control groups to glucose treatment groups. Taken together, this pilot study suggested that exogenous glucose in combination with a sublethal dose of antibiotics can disturb the metabolism of both methicillin-susceptible and resistant S. aureus, and enhance the antibiotic bactericidal effect.

The association of plasma peroxiredoxin 3 with insulin in pregnant women

Peroxiredoxin 3 (PRX3) is predominantly located in mitochondria and plays a major role in scavenging hydrogen peroxide of mitochondria. In the present study, we detected plasma PRX3 in pregnant women receiving oral glucose tolerance test at 24–28 gestational weeks. Plasma PRX3 was significantly increased about 1 h later than insulin secretion. In vitro detection of PRX3 in mouse islet cells showed up-regulation by more than 2-fold at 1 h and reached its top at 2 h of glucose stimulation, and the PRX3 level in cultured mediums was concomitantly elevated in a glucose concentration-dependent manner. In addition, both fasting plasma insulin and PRX3 were significantly higher in the subjects of term pregnancy as compared to that at 24–28 gestational weeks, and there was a positive correlation between plasma PRX3 and insulin. Our results indicate that PRX3 plays an active role in the response to insulin release. The positive association of plasma PRX3 and insulin suggest PRX3 to be a potential indicator of high insulin resistance.

Identification of differences in the formation of plasma glycated proteins between dogs and humans under diabetes-like glucose concentration conditions

Dogs have been proposed as a translational model and used for studying aging, diabetes, and diabetes-related complications in humans. However, no studies have ever compared the glycation of plasma proteins between dogs and humans under similar experimental conditions. Thus, the aim of this study was to fill this gap by comparing the plasma protein glycation patterns of dogs and humans in an ex-vivo system. Canine and human plasma samples were incubated with glucose at concentrations comparable to those observed in diabetic patients. The final glucose plasma concentration resulted in similar glucose:albumin ratios in both species. Glycated proteins were evaluated by measuring the content of fructosamine, protein carbonyls, and the formation of advanced glycation end-products (AGEs). The concentrations of fructosamine and protein carbonyls in canine and human plasma increased in a glucose concentration-dependent manner (P < 0.0001). Of note, the relative increment of fructosamine and protein carbonyl content and AGE formation was always higher in human than in dog plasma. Our results reveal that the plasma glycation processes in dogs and humans are not similar. These novel findings could contribute to improve our understating about canine and human diabetes as well as other condition associated in the glycation of proteins.

New-onset hyperglycemia immediately after liver transplantation: A national survey from China Liver Transplant Registry

BackgroundNew-onset hyperglycemia (NOH) is a common phenomenon after liver transplantation (LT), but its impact on clinical outcomes has not yet been fully assessed. We aimed to evaluate the etiology and prognosis of NOH within 1 month after LT. MethodsThe data of 3339 adult patients who underwent primary LT from donation after citizen death between January 2010 and June 2016 were extracted from China Liver Transplant Registry database and analyzed. NOH was defined as fasting blood glucose ≥7.0 mmol/L confirmed on at least two occasions within the first post-transplant month with or without hypoglycemic agent. ResultsOf 3339 liver recipients, 1416 (42.4%) developed NOH. Recipients with NOH had higher incidence of post-transplant complications such as graft and kidney failure, infection, biliary stricture, cholangitis, and tumor recurrence in a glucose concentration-dependent manner as compared to non-NOH recipients (P < 0.05). The independent risk factors of NOH were donor warm ischemic time >10 min, cold ischemic time >10 h, anhepatic time >60 min, recipient model for end-stage liver disease score >30, moderate ascites and corticosteroid usage (P < 0.05). Liver enzymes (alanine aminotransferase and gamma-glutamyltranspeptidase) on post-transplant day 7 significantly correlated with NOH (P < 0.001). ConclusionsNOH leads to increased morbidity and mortality in liver recipients. Close surveillance and tight control of blood glucose are desiderated immediately following LT particularly in those with delayed graft function and receiving corticosteroid. Strategic targeting graft ischemic injury may help maintain glucose homeostasis.

Designer fungus FAD glucose dehydrogenase capable of direct electron transfer

Fungi-derived flavin adenine dinucleotide glucose dehydrogenases (FADGDHs) are currently the most popular and advanced enzymes for self-monitoring of blood glucose sensors; however, the achievement of direct electron transfer (DET) with FADGDHs is difficult. In this study, a designer FADGDH was constructed by fusing Aspergillus flavus derived FADGDH (AfGDH) and a Phanerochaete chrisosporium CDH (PcCDH)-derived heme b-binding cytochrome domain to develop a novel FADGDH that is capable of direct electron transfer with an electrode. A structural prediction suggested that the heme in the CDH may exist in proximity to the FAD of AfGDH if the heme b-binding cytochrome domain is fused to the AfGDH N-terminal region. Spectroscopic observations of recombinantly produced designer FADGDH confirmed the intramolecular electron transfer between FAD and the heme. A decrease in pH and the presence of a divalent cation improved the intramolecular electron transfer. An enzyme electrode with the immobilized designer FADGDH showed an increase in current immediately after the addition of glucose in a glucose concentration-dependent manner, whereas those with wild-type AfGDH did not show an increase in current. Therefore, the designer FADGDH was confirmed to be a novel GDH that possesses electrode DET ability. The difference in the surface electrostatic potentials of AfGDH and the catalytic domain of PcCDH might be why their intramolecular electron transfer ability is inferior to that of CDH. These relevant and consistent findings provide us with a novel strategic approach for the improvement of the DET properties of designer FADGDH. (241 words)