Acute effects of hyperglycemia and hyperinsulinemia on hepatic oxidative stress and the systemic inflammatory response in rats

Machine learning-based prediction of risk factors for abnormal glycemic control in diabetic cancer patients receiving nutrition support: a case-control study

PURPOSE

To date, risk factors affecting abnormal glycemic control have not been investigated. This study aimed to analyze risk factors for hypoglycemia or hyperglycemia in diabetic cancer patients receiving nutritional support by using machine learning methods.

METHODS

This retrospective two-center study was performed using medical records. Odds ratios and adjusted odds ratios were estimated from univariate and multivariate analyses, respectively. Machine learning algorithms, including five-fold cross-validated multivariate logistic regression, elastic net, and random forest, were developed to predict risk factors for hypoglycemia and hyperglycemia.

RESULTS

Data from 127 patients were analyzed. The use of sulfonylurea (SU) and blood urea nitrogen (BUN) level > 20 mg/dL increased hypoglycemia by 6.3-fold (95% CI 1.30-30.47) and 5.0-fold (95% CI 1.06-23.46), respectively. In contrast, patients who received an actual energy intake/total energy expenditure (TEE) ≥ 120% and used dipeptidyl peptidase-4 (DPP-4) inhibitors had a higher risk of hyperglycemia by 19.3- (95% CI 1.46-254.78) and 3.3-fold (95% CI 1.23-8.61), respectively. An initial blood glucose level ≥ 182.5 mg/dL also increased the risk of hyperglycemia by 15.3-fold. AUROC values for all machine learning methods indicated acceptable and excellent performance for hypoglycemia and hyperglycemia.

CONCLUSION

The use of SU and BUN level > 20 mg/dL increased the risk of hypoglycemia, whereas an initial blood glucose level ≥ 182.5 mg/dL, a supplied actual energy intake/ TEE ≥ 120%, and the use of DPP-4 inhibitors increased the risk of hyperglycemia.

Redox Potential Correlates with Changes in Metabolite Concentrations Attributable to Pathways Active in Oxidative Stress Response in Swine Traumatic Shock

INTRODUCTION

Oxidation-reduction (redox) reactions, and the redox potential (RP) that must be maintained for proper cell function, lie at the heart of physiologic processes in critical illness. Imbalance in RP reflects systemic oxidative stress, and whole blood RP measures have been shown to correlate with oxygen debt level over time in swine traumatic shock. We hypothesize that RP measures reflect changing concentrations of metabolites involved in oxidative stress. To test this hypothesis, we compared blood and urine RP with concentrations of multiple metabolites in a swine traumatic shock model to identify meaningful RP-metabolite relationships.

METHODS

Seven swine were subjected to traumatic shock. Mixed venous (MV) RP, urine RP, and concurrent MV and urine metabolite concentrations were assessed at baseline, max O 2 Debt (80 mL/kg), end resuscitation, and 2 h post-resuscitation. RP was measured at collection via open circuit potential using nanoporous gold electrodes with Ag/AgCl reference and a ParstatMC potentiostat. Metabolite concentrations were measured by quantitative 1 H-NMR spectroscopy. MV and urine RP were compared with time-matched metabolites across all swine. LASSO regression with leave-one-out cross validation was used to determine meaningful RP/metabolite relationships. Metabolites had to maintain magnitude and direction of coefficients across 6 or more swine to be considered as having a meaningful relationship. KEGG IDs of these metabolites were uploaded into Metscape for pathway identification and evaluation for physiologic function.

RESULTS

Meaningful metabolite relationships (and mean coefficients across cross-validation folds) with MV RP included: choline (-6.27), ATP (-4.39), glycine (5.93), ADP (1.84), glucose (15.96), formate (-13.09), pyruvate (6.18), and taurine (-7.18). Relationships with urine RP were: betaine (4.81), urea (4.14), glycine (-2.97), taurine (10.32), 3-hydroxyisobutyrate (-7.67), N-phenylacetylglycine, PAG (-14.52), hippurate (12.89), and formate (-5.89). These meaningful metabolites were found to scavenge extracellular peroxide (pyruvate), inhibit ROS and activate cellular antioxidant defense (taurine), act as indicators of antioxidant mobilization against oxidative stress (glycine + PAG), and reflect renal hydroxyl radical trapping (hippurate), among other activities.

CONCLUSIONS

Real-time RP measures demonstrate significant relationships with metabolites attributable to metabolic pathways involved in systemic responses to oxidative stress, as well as those involved in these processes. These data support RP measures as a feasible, biologically relevant marker of oxidative stress. As a direct measure of redox state, RP may be a useful biomarker and clinical tool in guiding diagnosis and therapy in states of increased oxidative stress and may offer value as a marker for organ injury in these states as well.

Supplementation of Rumen-Protected Glucose Increased the Risk of Disturbance of Hepatic Metabolism in Early Postpartum Holstein Cows

The dual stress of reduced feed intake and increased milk yield in dairy cows early postpartum results in a negative energy balance. Rumen-protected glucose (RPG) has been reported to replenish energy, increase milk yield, and improve gut health. However, early postpartum cows often develop an insulin resistance, implying that RPG may not be well utilized and increased milk production may increase the liver’s fat oxidization burden. This study aimed to investigate the effects of RPG on the hepatic oxidative/antioxidative status and protein profile. Starting 7 d before expected calving, six pairs of cows were supplemented with rumen-protected glucose (RPG, n = 6) or with an equal amount of rumen-protecting coating fat (CON, n = 6). Liver samples were obtained from 10 cows 14 d after calving (d 14). Concentration of malondialdehyde and activity of glutathione peroxidase were increased and the activities of catalase and superoxide dismutase tended to increase in the livers of the RPG cows compared to the CON cows. The revised quantitative insulin sensitivity check index (RQUICKI) was decreased by RPG, but triacylglycerol concentration in liver was increased by RPG supplementation. The overall profiles of hepatic proteins were similar between CON and RPG. A partial least square regression was conducted to identify the proteins associated with liver lipidosis, oxidative stress, and antioxidative capacity. The top twenty proteins, according to their variable importance value, were selected for metabolic pathway enrichment analysis. Eighteen enriched KEGG pathways were identified, including metabolism, the citrate cycle, propanoate metabolism, the peroxisome, and type II diabetes mellitus. Our study showed that RPG supplementation reduced insulin sensitivity but increased the liver triglyceride concentration and the oxidative stress in early postpartum cows. Liver proteins related to lipidosis, oxidative stress, and antioxidative capacity, were positively associated with the glutamine metabolism, citric acid cycle, peroxisome, and type II diabetes pathways, which may indicate an increased risk of liver metabolic disorders caused by RPG supplementation in early postpartum cows.

The mechanism underlying extrapulmonary complications of the coronavirus disease 2019 and its therapeutic implication

The coronavirus disease 2019 (COVID-19) is a highly transmissible disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that poses a major threat to global public health. Although COVID-19 primarily affects the respiratory system, causing severe pneumonia and acute respiratory distress syndrome in severe cases, it can also result in multiple extrapulmonary complications. The pathogenesis of extrapulmonary damage in patients with COVID-19 is probably multifactorial, involving both the direct effects of SARS-CoV-2 and the indirect mechanisms associated with the host inflammatory response. Recognition of features and pathogenesis of extrapulmonary complications has clinical implications for identifying disease progression and designing therapeutic strategies. This review provides an overview of the extrapulmonary complications of COVID-19 from immunological and pathophysiologic perspectives and focuses on the pathogenesis and potential therapeutic targets for the management of COVID-19.

Systemic RNA oxidation can be used as a biomarker of infection in challenged with Vibrio parahaemolyticus

More and more evidence support the concept that RNA oxidation plays a substantial role in the progress of multiple diseases; however, only a few studies have reported RNA oxidation caused by microbial pathogens. Urinary 8-oxo-7,8-dihydroguanosine (8-oxo-Gsn) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGsn), which are broadly used as indicators of oxidative damage of RNA and DNA, were analyzed in this study to determine which can be used as a biomarker of infection in challenged with Vibrio parahaemolyticus (V. parahaemolyticus). In this work, 24 specific-pathogen-free (SPF) male SD rats were randomly divided into two groups: an infection group and a phosphate-buffered saline (PBS) control group. Our results proved that 8-oxo-Gsn rather than 8-oxo-dGsn was significantly increased after challenged with V. parahaemolyticus in urine and tissue samples of SD rats compared with the PBS control group. Simultaneously, white blood cells (WBCs) counts, intestinal inflammation and inflammatory factors (including CRP, IL-6, IL-1β, TNF-α, IL-10, and IL-17A) were also increased sharply. Which has more clinical value is that the trend of urinary 8-oxo-Gsn was consistent with WBCs, intestinal inflammation and all kinds of inflammatory factors. More importantly is that urinary 8-oxo-Gsn of infection group was positively correlated with WBCs and various inflammatory cytokines. In a word, our results demonstrated that as a systemic RNA oxidation biomarker, we hope 8-oxo-Gsn can be used as a biomarker of the severity of microbial pathogens infection, rather than a specific biomarker of microbial pathogens infection.

Hypothesized mechanisms explaining poor prognosis in type 2 diabetes patients with COVID-19: a review

PURPOSE

Epidemiological data suggest that comorbid patients, mostly those with type 2 diabetes (T2D), are predisposed to poor prognosis in Coronavirus disease 2019 (COVID-19), leading to serious healthcare concerns. The aim of the present manuscript is to review the main relevant mechanisms possibly contributing to worsen the clinical course of COVID-19 in T2D.

RESULTS

Poor glucose control, high glycaemic variability and diabetes-related comorbidities at baseline, particularly cardiovascular diseases and obesity, contribute in worsening the prognosis in the above-mentioned cluster of patients. Moreover, both a lower efficient innate immune system response and cytokine dysregulation predispose patients with T2D to impaired viral clearance and more serious pulmonary and systemic inflammation once the SARS-CoV-2 infection occurred. Inconclusive data are currently available for specifically indicate or contraindicate concurrent medications for managing T2D and its comorbidities in infected patients.

CONCLUSIONS

T2D individuals should be considered as more vulnerable to COVID-19 than general population, and thus require adequate advices about hygienic tips to protect themselves during the pandemic. A careful management of glucose levels and diabetes-related comorbidities remains essential for avoiding further complications, and patient monitoring during the pandemic should be performed also at distance by means of telemedicine. Further studies are needed to clarify whether medications normally used for managing T2D and its associated comorbidities could have a protective or detrimental effect on COVID-19 clinical course.

Toll-Like Receptor 4 and Inflammatory Micro-Environment of Pancreatic Islets in Type-2 Diabetes Mellitus: A Therapeutic Perspective

Patients with type-2 diabetes mellitus (T2DM) display chronic low-grade inflammation induced by activation of the innate immune system. Toll-like receptor (TLR)4 is a pattern recognition receptor that plays a vital part in activation of the innate immune system. Results from animal and computer-simulation studies have demonstrated that targeting TLR4 to block the TLR4-nuclear factor-kappa B (NF-κB) pathway reduces the inflammatory response and complications associated with T2DM. Therefore, TLR4-targeted therapy has broad prospects. Here, we reviewed the role of TLR4 in inflammation during chronic hyperglycemia in T2DM and its therapeutic prospects.

Gestational diabetes exacerbates maternal immune activation effects in the developing brain

Maternal inflammation and diabetes increase the risk for psychiatric disorders in offspring. We hypothesized that these co-occurring risk factors may potentiate each other. To test this, we maternally exposed developing mice in utero to gestational diabetes mellitus (GDM) and/or maternal immune activation (MIA). Fetal mouse brains were exposed to either vehicle, GDM, MIA or GDM+MIA. At gestational day (GD) 12.5, GDM produced a hyperglycemic, hyperleptinemic maternal state, whereas MIA produced significant increases in proinflammatory cytokines and chemokines. Each condition alone resulted in an altered, inflammatory and neurodevelopmental transcriptome profile. In addition, GDM+MIA heightened the maternal inflammatory state and gave rise to a new, specific transcriptional response. This exacerbated response was associated with pathways implicated in psychiatric disorders, including dopamine neuron differentiation and innate immune response. Based on these data, we hypothesize that children born to GDM mothers and exposed to midgestation infections have an increased vulnerability to psychiatric disorder later in life, and this should be tested in follow-up epidemiological studies.

Overfeeding-associated hyperglycemia and injury-response homeostasis in critically ill neonates

BACKGROUND

Injury severity induces a proportionate acute metabolic stress response, associated with increased risk of hyperglycemia. We hypothesized that excess caloric delivery (overfeeding) during high stress states would increase hyperglycemia and disrupt response homeostasis.

METHODS

Gestational age, daily weight, total daily caloric intake, serum C-reactive protein (CRP), prealbumin, and blood glucose concentrations in all acutely-injured premature NICU infants requiring TPN over the past 3years were reviewed. Injury severity was based on CRP and patients were divided into high (CRP ≥50mg/L) versus low (CRP <50mg/L) stress groups. Glycemic variability was used to measure disruption of homeostasis.

RESULTS

Overall sample included N=563 patient days (37 patients; 42 episodes). High stress group pre-albumin levels negatively correlated with CRP levels (R=-0.62, p<0.005). A test of equal variance demonstrated significantly increased high stress glycemic variability (Ha:ratio>1, Pr(F>f)=0.0353). When high stress patients were separated into high caloric intake (≥70kg/kcal/day) versus low caloric intake (<70kg/kcal/day), maximum serum glucose levels were significantly higher with overfeeding (230.33±55.81 vs. 135.71±37.97mg/dL, p<0.004).

CONCLUSION

Higher injury severity induces increased disruption of response homeostasis in critically ill neonates. TPN-associated overfeeding worsens injury-related hyperglycemia in more severely injured infants.

TYPE OF STUDY

Retrospective study.

LEVEL OF EVIDENCE

Level II.

Diabetes mellitus and risk of ovarian cancer. A systematic review and meta-analysis of 15 cohort studies

AIM

Diabetes mellitus (DM) is hypothesized to be associated with an increased risk of ovarian cancer (OC), but current evidences are inconsistent. We aimed to further study this association.

METHODS

PubMed, EMBASE, Web of Science, and Scopus were searched for eligible articles. After descriptive summary of the data, a random-effects model was applied in quantitative synthesis. Subgroup analysis was performed by study locales and settings, and sensitivity analysis was conducted based on restrictive selection criteria. Funnel plots and the Egger's test were used to assess publication bias. Statistical heterogeneity in meta-analysis was assessed by the P value derived from the Cochrane Q statistic and I-squared value.

RESULTS

Fourteen articles involving data of 15 cohort studies were included for our research. Overall, 17 risk ratios (RRs) were synthesized and yielded a pooled RR of 1.32 (95%CI: 1.14-1.52, P_Cochrane<0.001, I²=79.8%). Thirteen RRs were synthesized for type 2DM, and the pooled RR was 1.24 (95%CI: 1.06-1.44, P_Cochrane<0.001, I²=81.8%). Four RRs were synthesized for type 1DM, and the result was significant (RR: 1.83, 95%CI: 1.21-2.78, P_Cochrane=0.080, I²=55.7%). Results of sensitivity analysis suggested the robustness of a positive association between DM and OC risk, and subgroup analysis demonstrated that the association between DM and OC was much more substantial among Asia population. No publication bias was identified in meta-analysis.

CONCLUSION

Our study suggests there is a moderate relative increase in the risk of OC among DM patients. Future studies should investigate the effect of duration of DM and anti-diabetes intervention to OC risk.

l-Arginine supplementation improves rats' antioxidant system and exercise performance

Reactive species have great importance in sports performance, once they can directly regulate energy production, muscular contraction, inflammation, and fatigue. Therefore, the redox control is essential for athletes' performance. Studies demonstrated that l-arginine has an important role in the synthesis of urea, cell growth and production of nitric oxide, moreover, there are indications that it is also able to induce benefits to muscle antioxidant system through the upregulation of some antioxidant enzymes, and by inhibiting some pathways of reactive species production. Therefore, the aim of this study was to evaluate the effects of l-arginine supplementation on performance and oxidative stress of male rats (trained or not), submitted to a single session of high intensity exercise. Forty male Wistar rats were divided into four groups, control (C), control+l-arginine (C + A), trained (T), and trained+l-arginine (T + A). The aerobic training was conducted for 8 weeks. Data of maximum speed and time from tests were used as indicators of performance. Variables related to oxidative stress and antioxidant system were also evaluated. Aerobic training was capable to induce enhancements on animals' exercise performance and on their redox state. Additionally, supplementation improved rats' physical performance on both groups, control and trained. Different improvements between groups on the antioxidant capacity were observed. Nevertheless, considering the ergogenic effect of l-arginine and the lack of all positive adaptations promoted by the exercise training, untrained animals may be more exposed to oxidative damages after the practice of intense exercises.

Inhibition of TLR4 protects rat islets against lipopolysaccharide-induced dysfunction

Oxidative stress leads to dysfunction in pancreatic cells, causing a reduction in insulin secretion following exposure to glucose. Toll-like receptor 4 (TLR4) may be activated by exposure to lipopolysaccharide (LPS) stress. TLR4 may mediate the initiation of inflammatory and immune defense responses; however, the importance of the LPS/TLR4 interaction in apoptosis induced by oxidative stress in pancreatic β cells remains to be elucidated. The present study aimed to investigate the importance of TLR4 during LPS‑induced oxidative stress, apoptosis and dysfunction of insulin secretion in isolated islets of rats. LPS‑induced stimulation of TLR4 increased the production of reactive oxygen species and promoted apoptosis by upregulating the expression levels of caspase‑3, poly ADP ribose polymerase and altering the expression ratio of B‑cell lymphoma‑2 (Bcl‑2)/Bcl‑2 associated X protein. Additionally, the insulin secretion of islets cells was reduced. Anti‑TLR4 antibody and a knockdown of TLR4 by TLR4‑short hairpin RNA were used to inhibit TLR4 activity, which may reverse LPS‑induced events. The present study determined that in islets exposed to LPS oxidative stress, dysfunction may be partly mediated via the TLR4 pathway. Inhibition of TLR4 may prevent dysfunction of rat islets due to oxidative stress. The present study revealed that targeting the LPS/TLR4 signaling pathway and antioxidant therapy may be a novel treatment for the severely septic patients with hyperglycemia stress.

Modifying Risk Factors: Strategies That Work Diabetes Mellitus

An estimated 29.1 million Americans are currently diagnosed with diabetes, and this number is expected to increase to 48.3 million Americans by 2050. Correspondingly, the present burden of diabetes among patients undergoing total joint arthroplasty is significant and rising. Diabetes as a chronic condition is a well-established risk factor for complication after total joint arthroplasty. A growing body of evidence also indicates that hyperglycemia in the perioperative period, and not the diagnosis of diabetes alone, is similarly associated with increased complication risk. As a result, a coordinated approach to preoperative screening and optimization, combined with judicious perioperative glycemic control, may present an opportunity to improve outcomes, reduce complications, and avoid complication-related costs for patients undergoing total joint arthroplasty.

Pulsatile Hyperglycaemia Induces Vascular Oxidative Stress and GLUT 1 Expression More Potently than Sustained Hyperglycaemia in Rats on High Fat Diet

INTRODUCTION

Pulsatile hyperglycaemia resulting in oxidative stress may play an important role in the development of macrovascular complications. We investigated the effects of sustained vs. pulsatile hyperglycaemia in insulin resistant rats on markers of oxidative stress, enzyme expression and glucose metabolism in liver and aorta. We hypothesized that liver's ability to regulate the glucose homeostasis under varying states of hyperglycaemia may indirectly affect oxidative stress status in aorta despite the amount of glucose challenged with.

METHODS

Animals were infused with sustained high (SHG), low (SLG), pulsatile (PLG) glucose or saline (VEH) for 96 h. Oxidative stress status and key regulators of glucose metabolism in liver and aorta were investigated.

RESULTS

Similar response in plasma lipid oxidation was observed in PLG as in SHG. Likewise, in aorta, PLG and SHG displayed increased expression of glucose transporter 1 (GLUT1), gp-91PHOX and super oxide dismutase (SOD), while only the PLG group showed increased accumulation of oxidative stress and oxidised low density lipoprotein (oxLDL) in aorta.

CONCLUSION

Pulsatile hyperglycaemia induced relatively higher levels of oxidative stress systemically and in aorta in particular than overt sustained hyperglycaemia thus supporting the clinical observations that pulsatile hyperglycaemia is an independent risk factor for diabetes related macrovascular complications.

Impact of the Type of Continuous Insulin Administration on Metabolism in a Diabetic Rat Model

Exogenous insulin is the only treatment available for type 1 diabetic patients and is mostly administered by subcutaneous (SC) injection in a basal and bolus scheme using insulin pens (injection) or pumps (preimplanted SC catheter). Some divergence exists between these two modes of administration, since pumps provide better glycaemic control compared to injections in humans. The aim of this study was to compare the impacts of two modes of insulin administration (single injections of long-acting insulin or pump delivery of rapid-acting insulin) at the same dosage (4 IU/200 g/day) on rat metabolism and tissues. The rat weight and blood glucose levels were measured periodically after treatment. Immunostaining for signs of oxidative stress and for macrophages was performed on the liver and omental tissues. The continuous insulin delivery by pumps restored normoglycaemia, which induced the reduction of both reactive oxygen species and macrophage infiltration into the liver and omentum. Injections controlled the glucose levels for only a short period of time and therefore tissue stress and inflammation were elevated. In conclusion, the insulin administration mode has a crucial impact on rat metabolic parameters, which has to be taken into account when studies are designed.

The Negative Impact of Insulin Therapy for Acute Hyperglycemia Secondary to Glucose Load on Plasma Amino Acid Profiles in a Rat Model of Sepsis

Background: In critical illnesses, insulin therapy under overfed conditions with an excessive glucose infusion may cause metabolic disturbances in skeletal muscle mainly through muscle cell glucose uptake and the inhibition of physiological protein breakdown. The aim of this study was to examine the potential negative aspects of insulin therapy in a rat model of sepsis. Materials and Methods: Male Sprague-Dawley rats underwent cecal ligation and puncture (CLP) or sham surgery. A pre-established continuous intravenous glucose infusion was initiated immediately after surgery. Rats with sepsis were divided into four groups (n = 7 in each group) based on target blood glucose (BG) levels: a no glucose (NG) group (100-150 mg/dl), moderate glucose (MG) group (200-300 mg/dl), high glucose (HG) group (>300 mg/dl), and the hyperinsulinemia (HI) group, which received the same glucose infusion as the HG group with the insulin infusion (200-300 mg/dl). The sham group underwent sham surgery and received the same glucose infusion as the HG group. All rats were sacrificed 9 h after surgery, and blood samples were collected to measure plasma amino acid (AA) profiles. To examine survival rates in the 48 h following CLP, the HG, MG, and HI groups were newly prepared according to the aforementioned experimental design. Results: Plasma levels of the branched-chain AAs, glutamine, arginine, citrulline, and alanine among the septic groups slightly and inversely decreased with the amount of glucose infused, and HI had significantly lower values (p < 0.01). A strong correlation was observed among the AAs. Plasma 3-methylhistidine concentrations were the highest in the HI group. The survival rate of the HI group was greater than that of the HG, but did not reach the level of the MG group. Conclusion: In critical illnesses, insulin therapy under overfed conditions may impair the physiological supply of AAs and conditionally essential AA starvation, such as glutamine and arginine, and may have an adverse impact on the prognosis of patients.

The manner of the inflammation-boosting effect caused by acute hyperglycemia secondary to overfeeding and the effects of insulin therapy in a rat model of sepsis

BACKGROUND

The aim of the study was to investigate both the inflammation-boosting effect and the metabolic stress induced by acute hyperglycemia secondary to overfeeding with excessive glucose infusion and the effects of insulin therapy on those events in a rat model of sepsis.

MATERIALS AND METHODS

Sprague-Dawley rats underwent cecal ligation and puncture (CLP) or sham operation. Preestablished continuous intravenous glucose infusion was initiated immediately after surgery. First, rats with CLP-inducing sepsis were divided into three groups on the basis of the target blood glucose (BG) levels: high glucose (HG) group (overfed, >300 mg/dL), moderate glucose group (moderate hyperglycemia, 200-300 mg/dL), and no glucose group (100-150 mg/dL). The sham group received the same glucose infusion as that of the HG group. BG and plasma interleukin (IL) 6 levels were monitored over time. All rats were sacrificed 9 h after surgery to evaluate lung histology and measure hepatic total glutathione and malondialdehyde contents. Based on the results, the high glucose and insulin (HI) group was added to septic groups as a model of insulin therapy, in which insulin with the same HG dose as that in the HG group was administered to maintain moderate hyperglycemia.

RESULTS

BG level in all groups remained in the preestablished target range throughout the experiment. Plasma IL-6 level in all septic groups increased in a time-dependent manner, whereas that in the sham group with moderate hyperglycemia hardly increased. Nine hours after CLP, plasma IL-6 level in the HG group rose to 7407.5 ± 1987.3 pg/mL, which was three times higher than that in the other septic groups. There was no significant difference among moderate glucose, no glucose, and HI groups, in which BG level remained constant at <300 mg/dL. The HG group showed the worst consequences of lung injury and oxidative stress in the liver, which were completely stable in HI group.

CONCLUSIONS

Acute severe hyperglycemia in critical illness might excessively boost the existing systemic inflammatory response in a threshold-based manner. Insulin therapy under overfeeding could strongly inhibit such a boosting effect and oxidative stress in the liver.

Long-term exposure to nonylphenol affects insulin signaling in the liver of adult male rats

In the present study, we sought to investigate the long-term effects of nonylphenol (NP) on insulin signaling and glucose metabolism in liver. Furthermore, reactive oxygen species (ROS) in liver was evaluated as it is known to induce insulin resistance. Rats were administered NP by oral gavage at the doses of 15, 150 and 1500 μg/ kg body weight per day for 45 days. Hydrogen peroxide (H(2)O(2)) generation and lipid peroxidation were increased, and the activities of antioxidant enzymes were decreased in the liver of NP-treated rats. NP increased the plasma glucose and insulin levels and altered the enzymes of carbohydrate metabolism. Decrease in the protein levels of insulin signaling molecules insulin receptor (IR), IR substrate (IRS)-1, IRS-2 and phosphatidylinositol-3-kinase were observed with parallel increase in H(2)O(2) levels in the liver of NP-treated rats. These results suggest that NP downregulates insulin signaling in liver, which could be due to ROS production and oxidative damage.

Cytochrome P450 2E1 and hyperglycemia-induced liver injury

Cytochrome P450 2E1 (CYP2E1), a microsomal enzyme involved in xenobiotic metabolism and generation of oxidative stress, has been implicated in promoting liver injury. The review deals with the changes in various cellular pathways in liver linked with the changes in regulation of CYP2E1 under hyperglycemic conditions. Some of the hepatic abnormalities associated with hyperglycemia-mediated induction of CYP2E1 include increased oxidative stress, changes in mitochondrial structure and function, apoptosis, nitrosative stress, and increased ketone body accumulation. Thus, changes in regulation of CYP2E1 are associated with the injurious effects of hyperglycemia in liver.

The role of dysregulated glucose metabolism in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecologic cancer and also one of the most poorly understood. Other health issues that are affecting women with increasing frequency are obesity and diabetes, which are associated with dysglycemia and increased blood glucose. The Warburg Effect describes the ability of fast-growing cancer cells to preferentially metabolize glucose via anaerobic glycolysis rather than oxidative phosphorylation. Recent epidemiological studies have suggested a role for hyperglycemia in the pathogenesis of a number of cancers. If hyperglycemia contributes to tumour growth and progression, then it is intuitive that antihyperglycemic drugs may also have an important antitumour role. Preliminary reports suggest that these drugs not only reduce available plasma glucose, but also have direct effects on cancer cell viability through modification of molecular energy-sensing pathways. This review investigates the effect that hyperglycemia may have on EOC and the potential of antihyperglycemic drugs as therapeutic adjuncts.

Comparison of the effects of food versus protein restriction on selected nutritional and inflammatory markers in rats

We previously demonstrated that feeding a 2% protein AIN-76 diet ad libitum for 14 days resulted in substantial clinical and biochemical changes including weight loss, hypoglycemia, hypoalbuminemia, higher levels of plasma cytokines, oxidative stress in the liver, and activation of inflammatory signaling to interleukin (IL)-6, as compared with a 20% protein diet. In the present study, 54 rats were randomly given a standard rat chow diet ad libitum, or a 25% or 50% reduction of this intake for 14 days. The results showed that weight gain was less in the 25% food-restricted group and halted in the 50% group as compared with the control group. Unlike protein restriction, neither level of food restriction altered plasma levels of albumin and glucose, the hepatic protein abundance of signal transducers and activators of transcriptions and of mitogen-activated protein kinases, or the hepatic contents of total glutathione and malondialdehyde. The intracellular signaling in response to IL-6 stimulation was also well maintained. However, both levels of food restriction elevated IL-1 and corticosterone in plasma, did not alter ghrelin, and decreased plasma levels of free fatty acids. Because these latter 3 markers were not examined previously, 20 rats were fed an AIN-76 diet, either with 20% or 2% protein, ad libitum for 14 days. The 2% protein diet significantly decreased plasma levels of free fatty acids and increased ghrelin and corticosterone as compared with the 20% protein diet. Thus, food restriction, where all essential nutrients are reduced in proportion, is a physiologic stress that, while limiting growth, does not activate or impair the systemic inflammatory response, whereas a very low protein diet with little change in energy intake has a substantial impact on systemic inflammation, body composition, and growth.

Insulin inhibits tumor necrosis factor-alpha induction in myocardial ischemia/reperfusion: role of Akt and endothelial nitric oxide synthase phosphorylation

OBJECTIVES

Intensive insulin therapy with tight glucose control is known to result in reduced morbidity and mortality in inflammation-related critical illness. Tumor necrosis factor (TNF)-alpha induction in myocardial infarction may trigger inflammation and have detrimental effects on cardiomyocytes. This study was designed to investigate whether insulin attenuates TNF-alpha induction in acute myocardial ischemia/reperfusion (MI/R) and the underlying signaling mechanisms.

DESIGN

Randomized experimental study.

SETTING

Research laboratory.

SUBJECTS

Sprague-Dawley rats.

INTERVENTIONS

Anesthetized rats were subjected to MI/R (30 mins/3 hrs) and were treated with saline, glucose-insulin-potassium, or glucose-potassium infusion (4 mL/kg/hr intravenously). In vitro study was performed on cultured cardiomyocytes subjected to simulated ischemia/reperfusion (SI/R).

MEASUREMENTS AND MAIN RESULTS

In vivo treatment with glucose-insulin-potassium, but not glucose-potassium, significantly attenuated inflammatory response as evidenced by decreased TNF-alpha induction and myocardial myeloperoxidase activity, with concurrent reduction in creatine kinase activity and myocardial infarction compared with those in control rats. In cultured cardiomyocytes subjected to SI/R, insulin reduced TNF-alpha induction and increased Akt and endothelial nitric oxide synthase (eNOS) phosphorylation and subsequent nitric oxide (NO) production. Inhibition of insulin-stimulated NO production using either the PI3K inhibitor wortmannin or the NOS inhibitor L-NAME blocked TNF-alpha reduction afforded by insulin. Furthermore, the suppression on TNF-alpha by either insulin or TNF-alpha neutralizing antibody improved viability and reduced apoptosis of cardiomyocytes subjected to SI/R.

CONCLUSIONS

Our data showed that insulin inhibits ischemia/reperfusion-induced TNF-alpha production through the Akt-activated and eNOS-NO-dependent pathway in cardiomyocytes. The anti-inflammatory property elicited by insulin may contribute to its cardioprotective and prosurvival effects in the critically ill.

Glutathione metabolism in sepsis

Sepsis is characterized by severe redox imbalance. Glutathione plays a major role in cellular defenses against oxidative and nitrosative stress. There is limited information on the response of glutathione synthesis in human sepsis. This review proposes a critical analysis of available data on potential factors affecting glutathione synthesis in sepsis. Glutathione is synthesized from its constituent amino acids--glutamate, cysteine, and glycine. Cysteine availability and the activity of the enzyme glutamate cysteine ligase are rate-limiting for glutathione synthesis. Glutathione synthetic capacity is increased in liver and other tissues during the acute phase of experimental sepsis. Potential mechanisms for glutamate cysteine ligase activation in sepsis involve a decreased ratio of reduced/oxidized glutathione as well as the effects of reactive oxygen species, nitric oxide species, proinflammatory cytokines, heat shock proteins, and physical inactivity. Glutathione synthesis can be impaired by cysteine depletion, protein-energy malnutrition, hyperglycemia, glucocorticoid at pharmacologic doses, and decreased secretion of anterior pituitary hormones (growth hormones, thyrotropin, gonadotropins), as often observed in prolonged critical illness.