Flow cytometric analysis of glyoxalase-1 expression in human leukocytes

The protection conferred against ischemia-reperfusion injury in the diabetic brain by N-acetylcysteine is associated with decreased dicarbonyl stress

Diabetes, a risk factor for stroke, leads to elevated blood methylglyoxal (MG) levels. This is due to increased MG generation from the high glucose levels, and because diabetes impairs the glutathione (GSH)-glyoxalase system for MG elimination. MG glycates proteins and causes dicarbonyl stress. We investigated the contribution of MG and GSH to stroke outcome. Cerebral ischemia/reperfusion was performed in chemical-induced (streptozotocin) and genetic Akita mouse models of Type 1 diabetes. Brain infarction and functions of the GSH-dependent MG elimination pathway were determined. Diabetes increased post-ischemia-reperfusion cerebral infarct area in association with elevated MG and diminished GSH levels. Infarct size correlated with brain MG-to-GSH ratio. Expression of glutamate-cysteine ligase catalytic subunit (GCLc) was increased in diabetic brain. GCL activity was unchanged. MG-adducts were elevated in the diabetic brain and, using immunoprecipitation, we identified one of the bands as glycated occludin. This was accompanied by increased blood-brain barrier permeability. Total protein carbonyls were elevated, indicative of oxidative/carbonyl stress. N-acetylcysteine (NAC) corrected MG-to-GSH ratio, and reduced diabetic brain infarct area, occludin glycation and permeability. In addition, protein carbonyls were decreased by NAC. We showed that the diabetic brain exhibited a lower GSH-dependent potential for MG elimination, which contributed to increased protein glycation, and oxidative/carbonyl stress. The consequence of these changes was aggravated post-stroke brain injury. NAC administration protected against the exacerbated brain damage via restored GSH generation and normalization of the MG-to-GSH ratio and possibly by attenuating oxidative/carbonyl stress. This treatment could contribute to the successful management of stroke risk/outcome in diabetes.

Detection and Identification of Hematologic Malignancies and Solid Tumors by an Electrochemical Technique

Purpose

Develop and evaluate an electrochemical method to identify healthy individuals, malignant hematopathic patients and solid tumor patients by detecting the leukocytes in whole-blood.

Methods

A total of 114 individual blood samples obtained from our affiliated hospital in China (June 2015- August 2015) were divided into three groups: healthy individuals (n = 35), hematologic malignancies (n = 41) and solid tumors (n = 38). An electrochemical workstation system was used to measure differential pulse voltammetry due to the different electrochemical behaviors of leukocytes in blood samples. Then, one-way analysis of variance (ANOVA) was applied to analyze the scanning curves and to compare the peak potential and peak current.

Results

The scanning curve demonstrated the specific electrochemical behaviors of the blank potassium ferricyanide solution and that mixed with blood samples in different groups. Significant differences in mean peak potentials of mixture and shifts (ΔEp (mV)) were observed of the three groups (P< = 0.001). 106.00±9.00 and 3.14±7.48 for Group healthy individuals, 120.90±11.18 and 18.10±8.81 for Group hematologic malignancies, 136.84±11.53 and 32.89±10.50 for Group solid tumors, respectively. In contrast, there were no significant differences in the peak currents and shifts.

Conclusions

The newly developed method to apply the electrochemical workstation system to identify hematologic malignancies and solid tumors with good sensitivity and specificity might be effective, suggesting a potential utility in clinical application.

Association of reduced glyoxalase 1 activity and painful peripheral diabetic neuropathy in type 1 and 2 diabetes mellitus patients

AIMS

The present study was undertaken to investigate the relationship between glyoxalase 1 (Glo1) enzyme activity and painful diabetic neuropathy (DN) in patients with diabetes mellitus.

METHODS

Glo1 activity and biochemical markers were determined in blood samples from 108 patients with type 1 diabetes, 109 patients with type 2 diabetes, and 132 individuals without diabetes as a control. Painful and painless peripheral DN was assessed and multivariate regression analysis was used to determine independent association of Glo1 activity with occurrence of painful DN.

RESULTS

In patients with type 1 and type 2 diabetes mellitus and painful DN compared to patients with painless DN, Glo1 activity was significantly reduced by 12 and 14%, respectively. The increase in Glo1 activity was significantly associated with reduced occurrence of painful DN after adjusting for confounders by multivariate analysis.

CONCLUSIONS

Our results demonstrate for the first time that Glo1 activity is lower in patients with both types of diabetes mellitus who were diagnosed with painful DN. These data support the hypothesis that Glo1 activity modulates the phenotype of DN and warrant further investigation into the role of Glo1 in DN.

Identification of glyoxalase 1 polymorphisms associated with enzyme activity

The glyoxalase system and its main enzyme, glyoxalase 1 (GLO1), protect cells from advanced glycation end products (AGEs), such as methylglyoxal (MG) and other reactive dicarbonyls, the formation of which is increased in diabetes patients as a result of excessive glycolysis. MG is partly responsible for harmful protein alterations in living cells, notably in neurons, leading to their dysfunction, and recent studies have shown a negative correlation between GLO1 expression and tissue damage. Neuronal dysfunction is a common diabetes complication due to elevated blood sugar levels, leading to high levels of AGEs. The aim of our study was to determine whether single nucleotide polymorphisms (SNPs) in the GLO1 gene influence activity of the enzyme. In total, 125 healthy controls, 101 type 1 diabetes, and 100 type 2 diabetes patients were genotyped for three common SNPs, rs2736654 (A111E), rs1130534 (G124G), and rs1049346 (5'-UTR), in GLO1. GLO1 activity was determined in whole blood lysates for all participants of the study. Our results showed a significant association between the minor alleles rs1130534 and rs1049346 and decreased enzyme activity (P=0.001 and P=2.61×10(-5), respectively). Increased allelic counts of the risk alleles were strongly associated with decreased GLO1 activity (standardised β=-0.24, P=2.15×10(-5)), indicating independent actions of these variants on GLO1 activity, as supported by the haplotype analysis. We showed for the first time an association between genetic variants with GLO1 enzyme activity in humans. SNPs in GLO1 can be used to predict enzyme activity and detoxifying capabilities, but further studies are needed to link these SNPs with common complications in diabetes.

Glyoxalase 1 and glyoxalase 2 activities in blood and neuronal tissue samples from experimental animal models of obesity and type 2 diabetes mellitus

The glyoxalase enzymes catalyse the conversion of reactive glucose metabolites into non-toxic products as a part of the cellular defence system against glycation. This study investigated changes in glyoxalase 1 and glyoxalase 2 activities and the development of diabetic complications in experimental animal models of obesity (Zucker fa/fa rats) and type 2 diabetes mellitus (Goto-Kakizaki rats). In contrast to Zucker rats, in Goto-Kakizaki rats the glyoxalase 1 activities in brain, spinal cord and sciatic nerve tissues were significantly reduced by 10, 32 and 36 %, respectively. Lower glyoxalase 1 activity in the neuronal tissues was associated with a higher blood glucose concentration and impaired endothelium-dependent relaxation to acetylcholine in aortic rings in Goto-Kakizaki rats. This study provides evidence for disturbed neuronal glyoxalase 1 activity under conditions of hyperglycaemia in the presence of impaired endothelium-dependent relaxation and cognitive function.

Late-onset running biphasically improves redox balance, energy- and methylglyoxal-related status, as well as SIRT1 expression in mouse hippocampus

Despite the active research in this field, molecular mechanisms underlying exercise-induced beneficial effects on brain physiology and functions are still matter of debate, especially with regard to biological processes activated by regular exercise affecting the onset and progression of hippocampal aging in individuals unfamiliar with habitual physical activity. Since such responses seem to be mediated by changes in antioxidative, antiglycative and metabolic status, a possible exercise-induced coordinated response involving redox, methylglyoxal- and sirtuin-related molecular networks may be hypothesized. In this study, hippocampi of CD1 mice undergoing the transition from mature to middle age were analyzed for redox-related profile, oxidative and methylglyoxal-dependent damage patterns, energy metabolism, sirtuin1 and glyoxalase1 expression after a 2- or 4-mo treadmill running program. Our findings suggested that the 4-mo regular running lowered the chance of dicarbonyl and oxidative stress, activated mitochondrial catabolism and preserved sirtuin1-related neuroprotection. Surprisingly, the same cellular pathways were negatively affected by the first 2 months of exercise, thus showing an interesting biphasic response. In conclusion, the duration of exercise caused a profound shift in the response to regular running within the rodent hippocampus in a time-dependent fashion. This research revealed important details of the interaction between exercise and mammal hippocampus during the transition from mature to middle age, and this might help to develop non-pharmacological approaches aimed at retarding brain senescence, even in individuals unfamiliar with habitual exercise.