Natural Fatty Acid Guards against Brain Endothelial Cell Death and Microvascular Pathology following Ischemic Insult in the Presence of Acute Hyperglycemia

Ischemic stroke is worsened by the presence of sudden high blood sugar levels, even in individuals without pre-existing diabetes. This elevated glucose concentration hampers the ability of energy-starved brain cells to efficiently use it as a source of energy. Consequently, this leads to the production of abundant amounts of toxic glucose metabolites, which trigger oxidative stress in the brain milieu, particularly in the microvasculature of the brain. A prominent feature of this oxidative stress is the demise of endothelial cells, causing detrimental changes in blood vessels, including a reduction in their vascular diameter, a decreased efficiency of vessel proliferation, and the impaired integrity of tight junctions. These vascular pathologies contributed to an increase in the volume of damaged tissues (infarct), an exacerbation of brain swelling (edema), and a decline in cognitive and motor functions. In a mouse model of ischemic stroke with induced acute hyperglycemia, a naturally occurring saturated fatty acid provides protective cover to the microvasculature by preventing damage related to oxidative stress. Our current research revealed that lauric acid (LA) attenuated infarct volume and reduced brain edema by reducing endothelial cell death, enhancing vessels' diameter, promoting vascular angiogenesis, and stabilizing barrier functions. Animals administered with this natural compound showed a significant reduction in 4-HNE-positive vessels. In conclusion, natural saturated fatty acids help to preserve brain microvascular functions following ischemic insults in the presence of acute hyperglycemia.

Lipidomic Analysis to Assess the Correlation between Ceramides, Stress Hyperglycemia, and HbA1c in Acute Myocardial Infarction

Ceramides have been associated with cardiometabolic disease (e.g., acute myocardial infarction (AMI) and type 2 diabetes (T2D)) and adverse outcomes. Acute admission hyperglycemia (AH) is a transient glucose alteration in response to stress. As glycated hemoglobin (HbA1c) reflects the glycemia over a longer period of time, its use may be helpful in distinguishing between the AH and hyperglycemia associated with T2D in the AMI setting. The aim was to assess the correlation of ceramides with both AH (defined as an admission glucose level ≥140 mg/dL in the absence of T2D) and HbA1c-T2D and other demographic, clinical, and inflammatory-related biomarkers in AMI. High-performance liquid chromatography-tandem mass spectrometry was used to identify nine ceramide species, and their three ratios, in 140 AMI patients (FTGM coronary unit, Massa, Italy). The ceramides did not correlate with stress hyperglycemia, but specific species were elevated in T2D-AMI. Moreover, some ceramides were associated with other cardiometabolic risk factors. Ceramides assessment may be helpful in better understanding the pathogenic molecular mechanisms underlying myocardial acute events and cardiometabolic risk, as a basis for the future evaluation of their role as prognostic predictors and therapeutic targets in T2D-AMI patients.

Lack of Neuroprotective Effects of High-Density Lipoprotein Therapy in Stroke under Acute Hyperglycemic Conditions

Introduction: The pleiotropic protective effects of high-density lipoproteins (HDLs) on cerebral ischemia have never been tested under acute hyperglycemic conditions. The aim of this study is to evaluate the potential neuroprotective effect of HDL intracarotid injection in a mouse model of middle cerebral artery occlusion (MCAO) under hyperglycemic conditions. Methods: Forty-two mice were randomized to receive either an intracarotid injection of HDLs or saline. Acute hyperglycemia was induced by an intraperitoneal injection of glucose (2.2 g/kg) 20 min before MCAO. Infarct size (2,3,5-triphenyltetrazolium chloride (TTC)-staining), blood–brain barrier leakage (IgG infiltration), and hemorrhagic changes (hemoglobin assay by ELISA and hemorrhagic transformation score) were analyzed 24 h post-stroke. Brain tissue inflammation (IL-6 by ELISA, neutrophil infiltration and myeloperoxidase by immunohisto-fluorescence) and apoptosis (caspase 3 activation) were also assessed. Results: Intraperitoneal D-glucose injection allowed HDL- and saline-treated groups to reach a blood glucose level of 300 mg/dl in the acute phase of cerebral ischemia. HDL injection did not significantly reduce mortality (19% versus 29% in the saline-injected group) or cerebral infarct size (p = 0.25). Hemorrhagic transformations and inflammation parameters were not different between the two groups. In addition, HDL did not inhibit apoptosis under acute hyperglycemic conditions. Conclusion: We observed a nonsignificant decrease in cerebral infarct size in the HDL group. The deleterious consequences of reperfusion such as hemorrhagic transformation or inflammation were not improved by HDL infusion. In acute hyperglycemia, HDLs are not potent enough to counteract the adverse effects of hyperglycemia. The addition of antioxidants to therapeutic HDLs could improve their neuroprotective capacity.

Blood glucose concentration is unchanged during exposure to acute normobaric hypoxia in healthy humans

Normal blood [glucose] regulation is critical to support metabolism, particularly in contexts of metabolic stressors (e.g., exercise, high altitude hypoxia). Data regarding blood [glucose] regulation in hypoxia are inconclusive. We aimed to characterize blood [glucose] over 80 min following glucose ingestion during both normoxia and acute normobaric hypoxia. In a randomized cross-over design, on two separate days, 28 healthy participants (16 females; 21.8 ± 1.6 years; BMI 22.8 ± 2.5 kg/m2 ) were randomly exposed to either NX (room air; fraction of inspired [FI ]O2 ~0.21) or HX (FI O2 ~0.148) in a normobaric hypoxia chamber. Measured FI O2 and peripheral oxygen saturation were both lower at baseline in hypoxia (p < 0.001), which was maintained over 80 min, confirming the hypoxic intervention. Following a 10-min baseline (BL) under both conditions, participants consumed a standardized glucose beverage (75 g, 296 ml) and blood [glucose] and physiological variables were measured at BL intermittently over 80 min. Blood [glucose] was measured from finger capillary samples via glucometer. Initial fasted blood [glucose] was not different between trials (NX:4.8 ± 0.4 vs. HX:4.9 ± 0.4 mmol/L; p = 0.47). Blood [glucose] was sampled every 10 min (absolute, delta, and percent change) following glucose ingestion over 80 min, and was not different between conditions (p > 0.77). In addition, mean, peak, and time-to-peak responses during the 80 min were not different between conditions (p > 0.14). There were also no sex differences in these blood [glucose] responses in hypoxia. We conclude that glucose regulation is unchanged in young, healthy participants with exposure to acute steady-state normobaric hypoxia, likely due to counterbalancing mechanisms underlying blood [glucose] regulation in hypoxia.

The Role of Acute Hyperglycemia on the Risk of Malignant Arrhythmia in Acute Myocardial Infarction Patients: A Study of Myocardial Damage, Ion Channel Changes and Inflammatory Factors

BACKGROUND

acute myocardial infarction (AMI) is often followed by hyperglycemia. To date, there is no study that examine the role of myocardial damage, ion channel changes and increased inflammatory response as a pathomechanism of malignant arrhythmias due to hyperglycemia in AMI patients. The aim of this study is to determine the effect of acute hyperglycemia on the occurence of malignant arrhythmias, troponin I, VLP, echocardiographic strain, ion channel changes (CaMKII) and hsCRP. This study also aims to assess the effect of troponin I, VLP, GLS, CaMKII and hsCRP on the occurence of malignant arrhythmias in AMI patients with acute hyperglycemia.

METHODS

a cross-sectional study followed by a cohort study was conducted on AMI patients treated at ICCU Cipto Mangunkusumo Hospital Jakarta during November 2018 to May 2019 period. Patients with severe infections and who had experienced malignant arrhythmias at admission were excluded from the study. The occurence of malignant arrhythmias as the main outcome of this study and CaMKII level were assessed on the fifth day of treatment. Patients who died before the fifth day of treatment due to causes other than malignant arrhythmias were excluded from analysis. The association between acute hyperglycemia with VLP and the occurence of malignant arrhythmias was analyzed through a chi-square test, whereas the differences between troponin I, GLS, CaMKII and hsCRP, based on the hyperglycemia status of the patient, were analyzed by Mann-Whitney U test.

RESULTS

a total of 110 patients were included in the study. Two patients died on the third day of observation due to malignant arrhythmias. No significant relationship was found between acute hyperglycemia in AMI and malignant arrhythmias (RR = 1,38, 95%CI 0.50-3.77). There were differences of CaMKII level on day-1 and day-5 between those who were experienced malignant arrhytmia and those who were not (p-value for differences are 0,03 and 0,01, respectively. In the acute hyperglycemia group, there was difference of CaMKII day-5 levels between positive and negative VLP (p = 0.03).

CONCLUSION

it was concluded that the inititial stage of AMI causes more dominant myocardial damage, as compared to metabolic factors. In the next stage of AMI, acute hyperglycemia increases ROS and the activation of ion channel changes described by CaMKII. This change results in electrophysiological remodeling of the heart, as seen in the VLP image on SA-ECG.

Acute Hyperglycemia May Induce Renal Tubular Injury Through Mitophagy Inhibition

AIM

Acute hyperglycemia is closely related to kidney injury. Oxidative stress activation and notable mitochondria damages were found under acute hyperglycemia treatment in our previous work. In the present study, we explored the dose-effect relationship and the pivotal role of mitophagy in acute hyperglycemia induced tubular injuries.

METHODS

Forty non-diabetic SD rats were randomly divided and treated with different concentrations of hyperglycemia respectively during the 6-h clamp experiment. Renal morphological and functional alterations were detected. Rat renal tubular epithelial cells were treated with different concentrations of glucose for 6 h. Markers and the regulation pathway of mitophagy were analyzed.

RESULTS

Significant tubular injuries but not glomeruli were observed under both light and electron microscope after acute hyperglycemia treatment, which manifested as enlargement of tubular epithelial cells, disarrangement of epithelial cell labyrinths and swelling of mitochondria. Urinary microalbumin, β2-MG, CysC, NAG, GAL, and NGAL were increased significantly with the increase of blood glucose (P < 0.05). ROS was activated, mitochondrial membrane potential and LC3-II/LC3-I ratio were decreased but P62 and BNIP3L/Nix were increased in hyperglycemia groups (P < 0.05), which were reversed by AMPK activation or mTOR inhibition.

CONCLUSION

Acute hyperglycemia causes obvious tubular morphological and functional injuries in a dose-dependent manner. Acute hyperglycemia could inhibit mitophagy through AMPK/mTOR pathway, which would aggravate mitochondria damage and renal tubular impairment.

The clinical significance of hyperglycemia in nondiabetic critically ill multiple trauma patients

BACKGROUND

Information is inconsistent regarding the clinical role of acute elevations of blood glucose level secondary to hospital-acquired infections in nondiabetic critically ill patients during an intensive care unit stay. In this study we investigated the clinical significance of hyperglycemia related to new episodes of ventilator-associated pneumonia in nondiabetic critically ill multiple trauma intensive care unit patients.

MATERIALS AND METHODS

We analyzed the clinical data of 202 critically ill multiple trauma patients with no history of previous diabetes who developed a new ventilator-associated pneumonia episode during their intensive care unit stay. We used a time-from-event analysis method to assess whether acute changes in blood glucose levels that occurred prior to the onset of ventilator-associated pneumonia episodes had a different prognostic significance from those that occurred during such episodes. Glucose levels and other laboratory data were recorded for up to 5 days before ventilator-associated pneumonia events and for 5 days following these events.

RESULTS

Patients who required insulin therapy for persistent hyperglycemia related to a new ventilator-associated pneumonia event had a longer period of intensive care unit stay and a higher intensive care unit mortality rate than patients who did not require insulin for blood glucose control (p < 0.008 and <0.001 respectively). In addition, older age, administration of parenteral nutrition, and elevated mean blood glucose level parameters on the day following the day of diagnosis of a new ventilator-associated pneumonia episode were found to be independent risk factors for intensive care unit mortality.

CONCLUSION

Our study suggests that persistent hyperglycemia in nondiabetic critically ill patients, even treated by early insulin therapy, is an adverse prognostic factor of considerable clinical significance.

Acute Kidney Injury in Diabetic Patients With Acute Myocardial Infarction: Role of Acute and Chronic Glycemia

Background

In acute myocardial infarction, acute hyperglycemia is a predictor of acute kidney injury (AKI), particularly in patients without diabetes mellitus. This emphasizes the importance of an acute glycemic rise rather than glycemia level at admission. We investigated whether, in diabetic patients with acute myocardial infarction, the combined evaluation of acute and chronic glycemic levels may have better prognostic value for AKI than admission glycemia.

Methods and Results

At admission, we prospectively measured glycemia and estimated average chronic glucose levels (mg/dL) using glycosylated hemoglobin (HbA_1c), according to the following formula: 28.7×HbA_1c (%)−46.7. We evaluated the association with AKI of the acute/chronic glycemic ratio and of the difference between acute and chronic glycemia (Δ_A−C). We enrolled 474 diabetic patients with acute myocardial infarction. Of them, 77 (16%) experienced AKI. The incidence of AKI increased in parallel with the acute/chronic glycemic ratio (12%, 14%, 22%; P=0.02 for trend) and Δ_A−C (13%, 13%, 23%; P=0.01) but not with admission glycemic tertiles (P=0.22). At receiver operating characteristic analysis, the acute/chronic glycemic ratio (area under the curve: 0.62 [95% confidence interval, 0.55–0.69]; P=0.001) and Δ_A−C (area under the curve: 0.62 [95% confidence interval, 0.54–0.69]; P=0.002) accurately predicted AKI, without difference in the area under the curve between them (P=0.53). At reclassification analysis, the addition of the acute/chronic glycemic ratio and Δ_A−C to acute glycemia allowed proper AKI risk prediction in 16% of patients.

Conclusions

In diabetic patients with acute myocardial infarction, AKI is better predicted by the combined evaluation of acute and chronic glycemic values than by assessment of admission glycemia alone.

A hemorrhagic transformation model of mechanical stroke therapy with acute hyperglycemia in mice

Clinical benefit for mechanical thrombectomy (MT) in stroke was recently demonstrated in multiple large prospective studies. Acute hyperglycemia (HG) is an important risk factor of poor outcome in stroke patients, including those that underwent MT. The aim of this therapy is to achieve a complete reperfusion in a short time, given that reperfusion damage is dependent on the duration of ischemia. Here, we investigated the effects of acute HG in a mouse model of ischemic stroke induced by middle cerebral artery occlusion (MCAO). Hyperglycemic (intraperitoneal [ip] injection of glucose) and control (ip saline injection) 10-week male C57BL6 mice were subjected to MCAO (30, 90, and 180 min) followed by reperfusion obtained by withdrawal of the monofilament. Infarct volume, hemorrhagic transformation (HT), neutrophil infiltration, and neurological scores were assessed at 24 hr by performing vital staining, ELISA immunofluorescence, and behavioral test, respectively. Glucose injection led to transient HG (blood glucose = 250-390 mg/dL) that significantly increased infarct volume, HT, and worsened neurological outcome. In addition, we report that HG promoted blood-brain barrier disruption as shown by hemoglobin accumulation in the brain parenchyma and tended to increase neutrophil extravasation within the infarcted area. Acute HG increased neurovascular damage for all MCAO durations tested. HTs were observed as early as 90 min after ischemia under hyperglycemic conditions. This model mimics MT ischemia/reperfusion and allows the exploration of brain injury in hyperglycemic conditions.

Are there any effects of Sevoflurane and Desflurane anaesthesia on blood glucose levels in acute hyperglycemic diabetic rats?

AIM

The aim of this study was to investigate blood glucose level of desflurane and sevoflurane on blood glucose in diabetic rats undergoing acute hyperglycemia.

MATERIALS AND METHODS

In this study, 30 male Wistar albino rats were included. Diabetes was induced by a single IP injection of streptozotocin. After the effects of chronic diabetes encountered, diabetic rats were randomly assigned into diabetic control (group DC), diabetic hyperglycemia group (group DH), diabetic hyperglycemia group with desflurane (group DH-D), and diabetic hyperglycemia group with sevoflurane (group DH-S) groups. The normoglycemic groups received an IP injection of the same amount of saline. Hyperglycemic diabetic rats were anaesthetized by desflurane 6 % or sevoflurane 2 % at a dose, by which minimal alveolar concentration (MAC) for rats would be one. The drugs were given for 4 hours within 100 % oxygen at a rate of 6 L.min-1. One hour after cessation of inhalation anesthesia, blood glucose levels were determined at 1st, 4th and 24th hours. 24 hours after the anaesthesia.

RESULTS

Serum glucose was detected to be significantly lower in Group C, when compared to Groups DC, DH, DH-D and DH-S (p = 0.002, p = 0.001, p = 0.002, p = 0.003, respectively). Blood glucose levels in the diabetic groups were similar at the end of 6 weeks period, after hyperglycemia and anaesthesia induction.

CONCLUSION

We found out that sevoflurane and desflurane administrations in hyperglycemic rats were both related with insignificant blood glucose level increase at early post anaesthesia period and at post anaesthesia 24th hours. We still think that patients undergoing anaesthesia protocols with acute hyperglycemia need relatively longer follow up periods (Tab. 1, Ref. 28).

Inhibition of Toll-like receptor 4 signaling ameliorates lung ischemia-reperfusion injury in acute hyperglycemic conditions

BACKGROUND

Recent lung transplantation studies have shown that peri-operative hyperglycemia is an important factor affecting recipient survival; however, its underlying mechanisms are not well understood. We hypothesized that acute hyperglycemia exacerbates lung ischemia-reperfusion injury (IRI) through up-regulation of Toll-like receptor 4 (TLR4) signaling pathways.

METHODS

C57BL/6Ncr mice were divided into 3 treatment groups: sham; IRI; and IRI under acute hyperglycemic conditions (IRI+HG). Mice in the IRI and IRI+HG groups were exposed to IRI via clamping the left hilum for 1 hour, followed by reperfusion for 2 hours. Acute hyperglycemia was established by glucose injection. The severity of lung injury and TLR4 signaling pathway activity were assessed. Further, we performed a pharmacologic blockade of TLR4 signaling to determine the effect of TLR4 signaling inhibition on lung injury.

RESULTS

Compared with normoglycemic mice, hyperglycemic mice had 2-fold higher blood glucose levels (p < 0.001). Pulmonary compliance was significantly lower, and airway resistance was significantly higher, in the IRI+HG group than in the IRI group (p < 0.05). Levels of inflammatory cytokines in bronchoalveolar lavage fluid were significantly higher in the IRI+HG group than in the IRI group. Correspondingly, TLR4 signaling pathways were up-regulated in the IRI+HG group. Moreover, pharmacologic inhibition of TLR4 signaling significantly decreased lung injury markers under hyperglycemic conditions.

CONCLUSIONS

Acute hyperglycemia exacerbated lung IRI and was associated with up-regulation of TLR4 signaling pathways. Pharmacologic inhibition of TLR4 signaling ameliorated lung IRI with acute hyperglycemia. Targeting TLR4 appears to be a promising approach to managing coexisting pathologies in lung transplant recipients.

Fuzzy linguistic prediction model for sinoatrial node field potential analysis in acute hyperglycemia environment

The objective of this study is to build a fuzzy linguistic prediction model (FLPM) for analyzing the actuation duration of acute hyperglycemia to sinoatrial node field potential. The field potential was recorded using microelectrode arrays (MEA). The experimental data were analyzed using partial least squares (PLS), support vector machine (SVM), back propagation neural network (BPNN) and the proposed method. The experimental results showed that the fuzzy linguistic prediction model could be adopted for predicting the actuation duration of high glucose to the sinoatrial node field potential. Compared with the other aforementioned models, the proposed model had higher prediction accuracy.

The protective effect of the Mediterranean diet on endothelial resistance to GLP-1 in type 2 diabetes: a preliminary report

BACKGROUND

In type 2 diabetes, acute hyperglycemia worsens endothelial function and inflammation,while resistance to GLP-1 action occurs. All these phenomena seem to be related to the generation of oxidative stress. A Mediterranean diet, supplemented with olive oil, increases plasma antioxidant capacity, suggesting that its implementation can have a favorable effect on the aforementioned phenomena. In the present study, we test the hypothesis that a Mediterranean diet using olive oil can counteract the effects of acute hyperglycemia and can improve the resistance of the endothelium to GLP-1 action.

METHODS

Two groups of type 2 diabetic patients, each consisting of twelve subjects, participated in a randomized trial for three months, following a Mediterranean diet using olive oil or a control low-fat diet. Plasma antioxidant capacity, endothelial function, nitrotyrosine, 8-iso-PGF2a, IL-6 and ICAM-1 levels were evaluated at baseline and at the end of the study. The effect of GLP-1 during a hyperglycemic clamp, was also studied at baseline and at the end of the study.

RESULTS

Compared to the control diet, the Mediterranean diet increased plasma antioxidant capacity and improved basal endothelial function, nitrotyrosine, 8-iso-PGF2a, IL-6 and ICAM-1 levels. The Mediterranean diet also reduced the negative effects of acute hyperglycemia, induced by a hyperglycemic clamp, on endothelial function, nitrotyrosine, 8-iso-PGF2a, IL-6 and ICAM-1 levels. Furthermore, the Mediterranean diet improved the protective action of GLP-1 on endothelial function, nitrotyrosine, 8-iso-PGF2a, IL-6 and ICAM-1 levels, also increasing GLP-1-induced insulin secretion.

CONCLUSIONS

These data suggest that the Mediterranean diet, using olive oil, prevents the acute hyperglycemia effect on endothelial function, inflammation and oxidative stress, and improves the action of GLP-1, which may have a favorable effect on the management of type 2 diabetes, particularly for the prevention of cardiovascular disease.

Age-dependent differences in diabetes and acute hyperglycemia between men and women with ST-elevation myocardial infarction: a cohort study

BACKGROUND

Both acute hyperglycemia as diabetes results in an impaired prognosis in ST-elevation myocardial infarction (STEMI) patients. It is unknown whether there is a different prevalence of diabetes and acute hyperglycemia in men and women within age-groups.

METHODS

Between 2004 and 2010, 4640 consecutive patients (28% women) with STEMI, were referred for primary PCI. Patients were stratified into two age groups, < 65 years (2447 patients) and ≥65 years (2193 patients). Separate analyses were performed in 3901 patients without diabetes. Diabetes was defined as known diabetes or HbA1c ≥6.5 mmol/l at admission.

RESULTS

The prevalence of diabetes was comparable between women and men in the younger age group (14% vs 12%, p = 0.52), whereas in the older age group diabetes was more prevalent in women (25% vs 17% p < 0.001). In patients without diabetes, admission glucose was comparable between both genders in younger patients (8.1 ± 2.0 mmol/l vs 8.0 ± 2.2 mmol/l p = 0.36), but in older patients admission glucose was higher in women than in men (8.7 ± 2.1 mmol/l vs 8.4 ± 2.1 mmol/l p = 0.028). After multivariable analyses, the occurrence of increased admission glucose was comparable between men and women in the younger age group (OR 1.1, 95%CI 0.9-1.5), but increased in women in the older age group (OR 1.3, 95% CI 1.1-1.7). Both diabetes and hyperglycemia were associated with a higher one-year mortality in both men and women.

CONCLUSIONS

The differences between men and women in hyperglycemia and diabetes in patients with STEMI are age dependent and can only be observed in older patients. This may have implications for medical treatment and should be investigated further.