Oxidative stress and antioxidant defense in relation to the severity of diabetic polyneuropathy and cardiovascular autonomic neuropathy

Altered oxidant and antioxidant levels are associated with vascular stiffness and diabetic kidney disease in type 1 diabetes after exposure to acute and chronic hyperglycemia

BACKGROUND

Hyperglycemia-induced oxidative stress is a well-established pathological mediator of vascular complications in diabetes. We assessed plasma oxidant and antioxidant levels in response to acute and chronic hyperglycemia in relation to vascular stiffness and varying degrees of kidney disease in type 1 diabetes individuals.

METHODS

The acute hyperglycemia study included 22 type 1 diabetic individuals with normal albumin excretion rate (AER) and 13 non-diabetic controls. These individuals received an acute glucose challenge during a 120-minute hyperglycemic clamp. The chronic hyperglycemia study included 118 type 1 diabetic individuals with chronically low (n = 60) or high (n = 58) HbA1c concentrations and varying degrees of diabetic kidney disease (DKD) classified as normal, moderate, or severe albuminuria (AER). Levels of malondialdehyde (MDA), reactive oxygen metabolites (ROMs), total antioxidant capacity (TAC), biological antioxidant potential (BAP) and superoxide dismutase (SOD) were measured from plasma or serum samples in the FinnDiane study.

RESULTS

Levels of MDA (p < 0.01) and ROMs (p < 0.01) were elevated in type 1 diabetes individuals compared to non-diabetic controls at baseline. Acute hyperglycemia further increased MDA levels (p < 0.05) and sustained the elevation of ROMs in type 1 diabetes individuals. Acute hyperglycemic challenge impaired TAC in both non-diabetic (p < 0.05) and type 1 diabetes (p < 0.01) individuals compared to baseline whereas BAP was increased (p < 0.05) with no difference observed in non-diabetic controls. There was a positive association between high circulating MDA and AIx (r2 = 0.611, p = 0.05), and between delta ROMs and delta AIx (r2 = 0.955, p = 0.014) in combined analysis of individuals with type 1 diabetes and non-diabetic controls. Type 1 diabetes individuals with varying status of DKD, showed elevated levels of ROMs in those with high HbA1c compared to their counterpart with low HbA1c (p < 0.05). Individuals with severe albuminuria showed elevated ROM levels (p < 0.01) and depressed antioxidant capacity (p < 0.01) compared to those with normal AER of comparable HbA1c concentrations.

CONCLUSIONS

Biomarkers of oxidative stress are associated with vascular stiffness and DKD following acute and chronic hyperglycemic exposure and may provide added value to HbA1c in understanding disease pathology, predicting risk and assessing the status of secondary complications of type 1 diabetes.

Deoxy-sphingolipids, oxidative stress, and vitamin C correlate with qualitative and quantitative patterns of small fiber dysfunction and degeneration

ABSTRACT

Defined by dysfunction or degeneration of Aδ and C fibers, small fiber neuropathies (SFNs) entail a relevant health burden. In 50% of cases, the underlying cause cannot be identified or treated. In 100 individuals (70% female individuals; mean age: 44.8 years) with an idiopathic, skin biopsy-confirmed SFN, we characterized the symptomatic spectrum and measured markers of oxidative stress (vitamin C, selenium, and glutathione) and inflammation (transforming growth factor beta, tumor necrosis factor alpha), as well as neurotoxic 1-deoxy-sphingolipids. Neuropathic pain was the most abundant symptom (95%) and cause of daily life impairment (72%). Despite the common use of pain killers (64%), the painDETECT questionnaire revealed scores above 13 points in 80% of patients. In the quantitative sensory testing (QST), a dysfunction of Aδ fibers was observed in 70% and of C fibers in 44%, affecting the face, hands, or feet. Despite normal nerve conduction studies, QST revealed Aβ fiber involvement in 46% of patients' test areas. Despite absence of diabetes mellitus or mutations in SPTLC1 or SPTLC2 , plasma 1-deoxy-sphingolipids were significantly higher in the sensory loss patient cluster when compared with those in patients with thermal hyperalgesia ( P < 0.01) or those in the healthy category ( P < 0.1), correlating inversely with the intraepidermal nerve fiber density (1-deoxy-SA: P < 0.05, 1-deoxy-SO: P < 0.01). Patients with arterial hypertension, overweight (body mass index > 25 kg/m 2 ), or hyperlipidemia showed significantly lower L-serine (arterial hypertension: P < 0.01) and higher 1-deoxy-sphingolipid levels (arterial hypertension: P < 0.001, overweight: P < 0.001, hyperlipidemia: P < 0.01). Lower vitamin C levels correlated with functional Aβ involvement ( P < 0.05). Reduced glutathione was lower in patients with Aδ dysfunction ( P < 0.05). Idiopathic SFNs are heterogeneous. As a new pathomechanism, plasma 1-deoxy-sphingolipids might link the metabolic syndrome with small fiber degeneration.

Inflammation, oxidative stress and altered heat shock response in type 2 diabetes: the basis for new pharmacological and non-pharmacological interventions

Type 2 diabetes mellitus (DM2) is a chronic disease characterised by variable degrees of insulin resistance and impaired insulin secretion. Besides, several pieces of evidence have shown that chronic inflammation, oxidative stress, and 70 kDa heat shock proteins (HSP70) are strongly involved in DM2 and its complications, and various pharmacological and non-pharmacological treatment alternatives act in these processes/molecules to modulate them and ameliorate the disease. Besides, uncontrolled hyperglycaemia is related to several complications as diabetic retinopathy, neuropathy and hepatic, renal and cardiac complications. In this review, we address discuss the involvement of different inflammatory and pro-oxidant pathways related to DM2, and we described molecular targets modulated by therapeutics currently available to treat DM2.

Dietary Omega-3 Polyunsaturated Fatty-Acid Supplementation Upregulates Protective Cellular Pathways in Patients with Type 2 Diabetes Exhibiting Improvement in Painful Diabetic Neuropathy

Background: Omega-3 polyunsaturated fatty acids (PUFAs) have been proposed to improve chronic neuroinflammatory diseases in peripheral and central nervous systems. For instance, docosahexaenoic acid (DHA) protects nerve cells from noxious stimuli in vitro and in vivo. Recent reports link PUFA supplementation to improving painful diabetic neuropathy (pDN) symptoms, but cellular mechanisms responsible for this therapeutic effect are not well understood. The objective of this study is to identify distinct cellular pathways elicited by dietary omega-3 PUFA supplementation in patients with type 2 diabetes mellitus (T2DM) affected by pDN. Methods: Forty volunteers diagnosed with type 2 diabetes were enrolled in the “En Balance-PLUS” diabetes education study. The volunteers participated in weekly lifestyle/nutrition education and daily supplementation with 1000 mg DHA and 200 mg eicosapentaenoic acid. The Short-Form McGill Pain Questionnaire validated clinical determination of baseline and post-intervention pain complaints. Laboratory and untargeted metabolomics analyses were conducted using blood plasma collected at baseline and after three months of participation in the dietary regimen. The metabolomics data were analyzed using random forest, hierarchical clustering, ingenuity pathway analysis, and metabolic pathway mapping. Results: The data show that metabolites involved in oxidative stress and glutathione production shifted significantly to a more anti-inflammatory state post supplementation. Example of these metabolites include cystathionine (+90%), S-methylmethionine (+9%), glycine cysteine-glutathione disulfide (+157%) cysteinylglycine (+19%), glutamate (−11%), glycine (+11%), and arginine (+13.4%). In addition, the levels of phospholipids associated with improved membrane fluidity such as linoleoyl-docosahexaenoyl-glycerol (18:2/22:6) (+253%) were significantly increased. Ingenuity pathway analysis suggested several key bio functions associated with omega-3 PUFA supplementation such as formation of reactive oxygen species (p = 4.38 × 10−4, z-score = −1.96), peroxidation of lipids (p = 2.24 × 10−5, z-score = −1.944), Ca2+ transport (p = 1.55 × 10−4, z-score = −1.969), excitation of neurons (p = 1.07 ×10−4, z-score = −1.091), and concentration of glutathione (p = 3.06 × 10−4, z-score = 1.974). Conclusion: The reduction of pro-inflammatory and oxidative stress pathways following dietary omega-3 PUFA supplementation is consistent with the promising role of these fatty acids in reducing adverse symptoms associated with neuroinflammatory diseases and painful neuropathy.

Treatment for Diabetic Peripheral Neuropathy: What have we Learned from Animal Models?

INTRODUCTION

Animal models have been widely used to investigate the etiology and potential treatments for diabetic peripheral neuropathy. What we have learned from these studies and the extent to which this information has been adapted for the human condition will be the subject of this review article.

METHODS

A comprehensive search of the PubMed database was performed, and relevant articles on the topic were included in this review.

RESULTS

Extensive study of diabetic animal models has shown that the etiology of diabetic peripheral neuropathy is complex, with multiple mechanisms affecting neurons, Schwann cells, and the microvasculature, which contribute to the phenotypic nature of this most common complication of diabetes. Moreover, animal studies have demonstrated that the mechanisms related to peripheral neuropathy occurring in type 1 and type 2 diabetes are likely different, with hyperglycemia being the primary factor for neuropathology in type 1 diabetes, which contributes to a lesser extent in type 2 diabetes, whereas insulin resistance, hyperlipidemia, and other factors may have a greater role. Two of the earliest mechanisms described from animal studies as a cause for diabetic peripheral neuropathy were the activation of the aldose reductase pathway and increased non-enzymatic glycation. However, continuing research has identified numerous other potential factors that may contribute to diabetic peripheral neuropathy, including oxidative and inflammatory stress, dysregulation of protein kinase C and hexosamine pathways, and decreased neurotrophic support. In addition, recent studies have demonstrated that peripheral neuropathy-like symptoms are present in animal models, representing pre-diabetes in the absence of hyperglycemia.

CONCLUSION

This complexity complicates the successful treatment of diabetic peripheral neuropathy, and results in the poor outcome of translating successful treatments from animal studies to human clinical trials.

Exercise as Treatment for Neuropathy in the Setting of Diabetes and Prediabetic Metabolic Syndrome: A Review of Animal Models and Human Trials

BACKGROUND

Peripheral neuropathy is among the most common complications of diabetes, but a phenotypically identical distal sensory predominant, painful axonopathy afflicts patients with prediabetic metabolic syndrome, exemplifying a spectrum of risk and continuity of pathogenesis. No pharmacological treatment convincingly improves neuropathy in the setting of metabolic syndrome, but evolving data suggest that exercise may be a promising alternative.

OBJECTIVE

The aim of the study was to review in depth the current literature regarding exercise treatment of metabolic syndrome neuropathy in humans and animal models, highlight the diverse mechanisms by which exercise exerts beneficial effects, and examine adherence limitations, safety aspects, modes and dose of exercise.

RESULTS

Rodent models that recapitulate the organismal milieu of prediabetic metabolic syndrome and the phenotype of its neuropathy provide a strong platform to dissect exercise effects on neuropathy pathogenesis. In these models, exercise reverses hyperglycemia and consequent oxidative and nitrosative stress, improves microvascular vasoreactivity, enhances axonal transport, ameliorates the lipotoxicity and inflammatory effects of hyperlipidemia and obesity, supports neuronal survival and regeneration following injury, and enhances mitochondrial bioenergetics at the distal axon. Prospective human studies are limited in scale but suggest exercise to improve cutaneous nerve regenerative capacity, neuropathic pain, and task-specific functional performance measures of gait and balance. Like other heath behavioral interventions, the benefits of exercise are limited by patient adherence.

CONCLUSION

Exercise is an integrative therapy that potently reduces cellular inflammatory state and improves distal axonal oxidative metabolism to ameliorate features of neuropathy in metabolic syndrome. The intensity of exercise need not improve cardinal features of metabolic syndrome, including weight, glucose control, to exert beneficial effects.

Cardiovagal modulation and oxidative stress in hypothyroidism on maintenance therapy

AIM

To analyze the autonomic control of heart rate variability (HRV) in subjects with peripheral hypothroidism undergoing hormone replacement therapy with L-thyroxine (L-T4) for 5-10 years.

METHODS

Thyroid profile, lipid profile, lipid-risk factors, parameters of oxidative stress [malondialdehyde (MDA)], inflammation [high-sensitive C-reactive protein (CRP)] and Heart rate variability (HRV) was analyzed in thirty-eight hypothyroid patients on treatment for more than five years and compared with healthy euthyroid volunteers of similar age, gender, and body composition. The link of oxidative stress with HRV parameters was assessed by Spearman-Rho correlation and regression analyses.

RESULTS

Hypothyroid patients on L-T4 treatment, had higher TSH (p<0.01), lipid profile (p<0.05) and lipid risk factors (p<0.05), high-sensitive C-reactive-protein (hsCRP) (3.31 versus 4.95 mg/L; p<0.05) and MDA (2.66 versus 6.87 μm/L; p <0.001) in serum. There was gross reduction in HRV parameters [reduced standard deviation of NN interval (SDNN), root mean square of successive differences between normal heartbeats (RMSSD), total power (TP) and elevated ratio of low to high frequency power (LF/HF ratio)] in patients. Elevated MDA was correlated with vagal withdrawal (decreased SDNN, RMSSD and TP) and TSH. In multiple regression analysis TSH and TP contributed to the rise in MDA.

CONCLUSION

Hormone replacement therapy with L-T4 for hypothyroidism alone does not resolve persistent hyperlipidemia, oxidative stress and inflammation in primary hypothyroid patients even after five years of treatment. Association of oxidative stress with reduced cardiovagal modulation in these patients suggests persistence of cardiovascular risk despite standard treatment which warrants further investigation.

Association of Oxidative Stress with Neurological Disorders

BACKGORUND

Oxidative stress is one of the main contributing factors involved in cerebral biochemical impairment. The higher susceptibility of the central nervous system to reactive oxygen species mediated damage could be attributed to several factors. For example, neurons use a greater quantity of oxygen, many parts of the brain have higher concentraton of iron, and neuronal mitochondria produce huge content of hydrogen peroxide. In addition, neuronal membranes have polyunsaturated fatty acids, which are predominantly vulnerable to oxidative stress (OS). OS is the imbalance between reactive oxygen species generation and cellular antioxidant potential. This may lead to various pathological conditions and diseases, especially neurodegenerative diseases such as, Parkinson's, Alzheimer's, and Huntington's diseases.

OBJECTIVES

In this study, we explored the involvement of OS in neurodegenerative diseases.

METHODS

We used different search terms like "oxidative stress and neurological disorders" "free radicals and neurodegenerative disorders" "oxidative stress, free radicals, and neurological disorders" and "association of oxidative stress with the name of disorders taken from the list of neurological disorders. We tried to summarize the source, biological effects, and physiologic functions of ROS.

RESULTS

Finally, it was noted that more than 190 neurological disorders are associated with oxidative stress.

CONCLUSION

More elaborated studies in the future will certainly help in understanding the exact mechanism involved in neurological diseases and provide insight into revelation of therapeutic targets.

Bilirubin is inversely related to diabetic peripheral neuropathy assessed by sural nerve conduction study

AIMS/INTRODUCTION

Diagnosis of diabetic peripheral neuropathy (DPN) depends on subjective findings, certain investigations for DPN risks have not been performed enough. Bilirubin protects against vascular complications by reducing oxidative stress in diabetes, but is not fully tested for DPN. This study aimed to evaluate sural nerve conduction impairments (SNCI) as an objective DPN marker and the contribution of bilirubin to SNCI.

MATERIALS AND METHODS

Using DPN-Check® , SNCI was defined as a decline of amplitude potential or conduction velocity below the normal limit in 150 inpatients with diabetes. The correlations between SNCI and conventional DPN diagnosis criteria, the incidence of diabetic retinopathy/nephropathy, biomarkers for atherosclerosis, cardiac function by ultrasonic cardiogram, and bilirubin were statistically tested, followed by the comparison of logistic regression models for SNCI to find confounders with bilirubin.

RESULTS

The incidence of SNCI was 72.0%. The sensitivity and specificity of SNCI for DPN prediagnosis by simplified criteria were 54.6 and 90.5%, respectively, and similarly corresponded with diabetic retinopathy and nephropathy (sensitivity 57.4 and 50.0%, respectively). SNCI significantly related to diabetes duration, declined estimated glomerular filtration rate, albuminuria and total bilirubin. SNCI incidence was attenuated in the higher bilirubin tertiles (89.8/65.3/54.8%, P < 0.001). Bilirubin was an independent inverse risk factor for SNCI, even after adjustment by known risk factors for DPN and markers for microvascular complications.

CONCLUSIONS

SNCI is a comprehensive marker for diabetic complications. We first showed the independent inverse relationship between bilirubin and SNCI through the independent pathway with other complications, provably reducing oxidative stress, as previously reported.

The role of biofactors in the prevention and treatment of age-related diseases

The present demographic changes toward an aging society caused a rise in the number of senior citizens and the incidence and burden of age-related diseases (such as cardiovascular diseases [CVD], cancer, nonalcoholic fatty liver disease [NAFLD], diabetes mellitus, and dementia), of which nearly half is attributable to the population ≥60 years of age. Deficiencies in individual nutrients have been associated with increased risks for age-related diseases and high intakes and/or blood concentrations with risk reduction. Nutrition in general and the dietary intake of essential and nonessential biofactors is a major determinant of human health, the risk to develop age-related diseases, and ultimately of mortality in the older population. These biofactors can be a cost-effective strategy to prevent or, in some cases, even treat age-related diseases. Examples reviewed herein include omega-3 fatty acids and dietary fiber for the prevention of CVD, α-tocopherol (vitamin E) for the treatment of biopsy-proven nonalcoholic steatohepatitis, vitamin D for the prevention of neurodegenerative diseases, thiamine and α-lipoic acid for the treatment of diabetic neuropathy, and the role of folate in cancer epigenetics. This list of potentially helpful biofactors in the prevention and treatment of age-related diseases, however, is not exhaustive and many more examples exist. Furthermore, since there is currently no generally accepted definition of the term biofactors, we here propose a definition that, when adopted by scientists, will enable a harmonization and consistent use of the term in the scientific literature.

QM/MM analysis, synthesis and biological evaluation of epalrestat based mutual-prodrugs for diabetic neuropathy and nephropathy

Herein, a quantum mechanics/molecular mechanics (QM/MM) based biotransformation study was performed on synthetically feasible mutual-prodrugs of epalrestat which have been identified from an in-house database developed by us. These prodrugs were submitted to quantum polarized ligand docking (QPLD) with the CES1 enzyme followed by MM-GBSA calculation. Electronic aspects of transition state of these prodrugs were also considered to study the catalytic process through density functional theory (DFT). ADMET analysis of prodrugs was then carried out to assess the drug-likeness. On the basis of in-silico results, the best five prodrugs were synthesized and further evaluated for their neuroprotective and nephroprotective potential in high-fat diet-streptozotocin (HFD-STZ) induced diabetes in rat model. Clinically relevant molecular manifestations of diabetic complications (DC) including aldose reductase (ALR2) activity and oxidative stress markers such as reduced glutathione (GSH), catalase (CAT), and thiobarbituric acid reactive substances (TBARS) were determined in blood plasma as well as tissues of the brain and kidneys. The histopathological examination of these organs was also carried out to see the improvement in structural deformities caused due to neuropathy and nephropathy. Finally, in-vivo pharmacokinetic study was performed for the best two prodrugs to assess the improvement in biopharmaceutical attributes of parent drugs. Overall, EP-G-MFA and EP-MFA have significantly reduced the hyperglycemia-induced ALR2 activity, levels of oxidative stress markers, and manifested about a two-fold increase in the biological half-life (T_1/2) of parent drugs. The overall findings of this study suggest that methyl ferulate conjugated prodrugs of epalrestat may be considered as potential protective agents in diabetic neuropathy and nephropathy.

Increased Oxidative Stress Underlies Abnormal Pain Threshold in a Normoglycemic Japanese Population

Normal-high HbA1c levels are a risk factor for attenuated pain sensation in normoglycemic subjects. It is unclear, however, what mechanisms underlie the pathogenesis of attenuated pain sensation in such a population. We, therefore, explored the relationship between oxidative stress (OS) and pain sensation in a rural Japanese population. A population-based study of 894 individuals (average age 53.8 ± 0.5 years) and 55 subjects with impaired fasting glucose (IFG) were enrolled in this study. Individuals with diabetes were excluded. Relationships between pain threshold induced by intraepidermal electrical stimulation (PINT) and clinico-hematological parameters associated with OS were evaluated. Univariate linear regression analyses revealed age, BMI, HbA1c, the OS biomarker urine 8-hydroxy-2'-deoxyguanosine (8-OHdG), systolic blood pressure, and decreased Achilles tendon reflex on the PINT scores. Adjustments for age, gender, and multiple clinical measures confirmed a positive correlation between PINT scores and urine 8-OHdG (β = 0.09, p < 0.01). Urine 8-OHdG correlated positively with higher HbA1c levels and age in the normoglycemic population. Unlike in the normoglycemic population, both inflammation and OS were correlated with elevated PINT scores in IFG subjects. OS may be a major contributing factor to elevated PINT scores in a healthy Japanese population.

Role of Oxidative Stress in Hepatic and Extrahepatic Dysfunctions during Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is a pathology that contains a broad liver dysfunctions spectrum. These alterations span from noninflammatory isolated steatosis until nonalcoholic steatohepatitis (NASH), a more aggressive form of the disease characterized by steatosis, inflammatory status, and varying liver degrees fibrosis. NAFLD is the most prevalent chronic liver disease worldwide. The causes of NAFLD are diverse and include genetic and environmental factors. The presence of NASH is strongly associated with cirrhosis development and hepatocellular carcinoma, two conditions that require liver transplantation. The liver alterations during NAFLD are well described. Interestingly, this pathological condition also affects other critical tissues and organs, such as skeletal muscle and even the cardiovascular, renal, and nervous systems. Oxidative stress (OS) is a harmful state present in several chronic diseases, such as NAFLD. The purpose of this review is to describe hepatic and extrahepatic dysfunctions in NAFLD. We will also review the influence of OS on the physiopathological events that affect the critical function of the liver and peripheral tissues.

Lipopolysaccharide-binding protein is a distinctive biomarker of abnormal pain threshold in the general Japanese population

INTRODUCTION

Small fiber neuropathy (SFN) is an early manifestation in diabetic polyneuropathy (DPN); however, the mechanisms are not fully understood. In diabetes, SFN is presumed to be common in individuals with overt DPN, enhancing activation of polyol pathway, oxidative stress, advanced glycation end products (AGEs), and inflammation. We explored the relationship between clinicohematological factors related to DPN and pain sensation in the Japanese population.

RESEARCH DESIGN AND METHODS

We conducted a population-based study, recruiting 1030 individuals (average age 54.4±0.5 years), in 2017, to participate in our Iwaki project. After initial screening by fasting blood glucose and glycohemoglobin A1c (HbA1c) measurements, the subjects were categorized into control (n=894), type 2 diabetes (n=81), and impaired fasting glucose (n=55) groups. Clinical data were gathered, and relationships between pain threshold from intraepidermal electrical stimulation (PINT) and DPN were examined by analysis of variance, post hoc test, and χ² tests to study correlations among and between groups of the clinical data and DPN.

RESULTS

Univariate linear regression analyses showed significant correlations between PINT and serum lipopolysaccharide-binding protein (LBP) level (ß=0.1025, p=0.001). Adjustments for the clinical measurements confirmed a positive correlation (ß=0.070, p=0.034). Logistic regression analysis revealed high LBP value (>6.7 mg/dL) as a significant risk factor toward abnormal PINT (≥0.35 mA). LBP significantly correlated with the high-sensitivity C reactive protein, inflammation marker, elevated similarly in both pre-diabetic and overt-diabetic groups, compared with controls, but it did not correlate with a decreased Achilles tendon reflex. In contrast, urine 8-hydroxy-2'-deoxyguanosine, oxidative stress marker, and pentosidine, AGEs, markedly increased in individuals with type 2 diabetes with high HbA1c.

CONCLUSIONS

Individuals with high LBP exhibited an elevated PINT in the Japanese population. Low level of inflammation evoked by metabolic endotoxemia is possibly implicated in the pathophysiology of SFN from pre-diabetic stage.

γ-Linolenic Acid versus α-Lipoic Acid for Treating Painful Diabetic Neuropathy in Adults: A 12-Week, Double-Placebo, Randomized, Noninferiority Trial

BACKGROUND

This study was a multicenter, parallel-group, double-blind, double-dummy, randomized, noninferiority trial to evaluate the efficacy and safety of γ-linolenic acid (GLA) relative to α-lipoic acid (ALA) over a 12-week treatment period in type 2 diabetes mellitus (T2DM) patients with painful diabetic peripheral neuropathy (DPN).

METHODS

This study included 100 T2DM patients between 20 and 75 years of age who had painful DPN and received either GLA (320 mg/day) and placebo or ALA (600 mg/day) and placebo for 12 weeks. The primary outcome measures were mean changes in pain intensities as measured by the visual analogue scale (VAS) and the total symptom scores (TSS).

RESULTS

Of the 100 subjects who initially participated in the study, 73 completed the 12-week treatment period. Per-protocol analyses revealed significant decreases in the mean VAS and TSS scores compared to baseline in both groups, but there were no significant differences between the groups. The treatment difference for the VAS (95% confidence interval [CI]) between the two groups was -0.65 (-1.526 to 0.213) and the upper bound of the 95% CI did not exceed the predefined noninferiority margin (δ₁=0.51). For the TSS, the treatment difference was -0.05 (-1.211 to 1.101) but the upper bound of the 95% CI crossed the noninferiority margin (δ₂=0.054). There were no serious adverse events associated with the treatments.

CONCLUSION

GLA treatment in patients with painful DPN was noninferior to ALA in terms of reducing pain intensity measured by the VAS over 12 weeks.

The Protective Effect and Mechanism of Dexmedetomidine on Diabetic Peripheral Neuropathy in Rats

Objective

To investigate the role of dexmedetomidine (DEX) in the inhibition of diabetic peripheral neuropathy (DPN) and the protection in the nerve damage.

Methods

Eighty male Sprague-Dawley (SD) rats were randomly allocated to four groups: the control group (C group), DPN model group (DPN group), DEX-treated group (DEX group), and the yohimbine treated group (YOH group). DPN was induced by intraperitoneal administration of streptozocin (STZ) (35 mg/kg). The body weights, blood glucose level, mechanical withdrawal threshold (MWT), thermal withdrawal latency (TWL), the motor, and sensory nerve conduction velocities (MNCV and SNCV) of sciatic nerve were measured. Then the sciatic nerve was isolated for H&E staining and immunohistochemical staining. The oxidative stress makers such as malondialdehyde (MDA), superoxide-dismutase (SOD), and glutathione peroxidase (GSH-Px) and apoptosis related cytokines such as Bax, Bcl-2, and caspase-3 were estimated.

Results

There was no significant difference of the blood glucose and body weight among the DPN group, DEX group, and YOH group. H&E staining showed that DEX treatment can ameliorate the damage of sciatic nerve cells. In the DPN group, MWT, TWL, MNCV, and SNCV were significantly reduced compared with the C group (P < 0.05). In DEX group rats, MWT, TWL, MNCV, and SNCV were increased significantly (P < 0.05) compared with the DPN group and YOH group rats. Lower SOD and GSH-Px, and higher MDA were found in the DPN group compared with the C group (P < 0.01), and DEX treatment restored SOD, GSH-px, and MDA activity significantly (P < 0.01). The expression levels of Bax and caspase-3 were increased, while that of Bcl-2 was decreased significantly in the DPN group compared with the C group (P < 0.05). In the DEX group, the expression levels of Bax and caspase-3 were decreased significantly (P < 0.05), while that of Bcl-2 was increased significantly (P < 0.05) compared with the DPN group and the YOH group.

Conclusion

The results of this study demonstrated that DEX has the inhibitory and protective effects on DPN of rats. This may be associated with its antioxidative and anti-apoptosis responses.

Vitamin C ameliorated cardiac autonomic neuropathy in type 2 diabetic rats

BACKGROUND

Vitamin C (VC) is a common antioxidant with cell protection potentials. However, its possible protective effect on cardiac autonomic nerves from diabetic induced insults is yet to be explored.

AIM

To investigate the effects of VC on diabetic cardiac autonomic neuropathy.

METHODS

Thirty male Wistar rats were equally grouped into control, diabetic and diabetic + VC. Type 2 diabetes was induced with fructose diet and alloxan. VC (1 g/kg) was administered for 4 wk via oral canula. Blood pressure and heart rate were measured non-invasively using tail flick blood pressure monitor. Spectral analysis of heart rate variability (HRV) was used to assess cardiac autonomic neuropathy. Blood was collected from the ocular sinus for biochemical analysis. Urethane (1 g/kg-ip) was used for anaesthesia prior to HRV and cervical dislocation to harvest hearts. Intracardiac autonomic nerve was assessed using tyrosine hydroxylase immunohistochemistry on fixed heart sections.

RESULTS

Results were analysed using ANOVA at α_0.05. Unlike VC and control groups, diabetic rats showed significantly (P < 0.0001) reduced HRV, increased heart-rate and blood pressure, initial increase in cardiac tyrosine hydroxylase activities at week-2 and sparse activity at week-4 of diabetes. Furthermore, apolipoprotein B, Oxidative stress and inflammatory markers were significantly (P < 0.01) reduced in VC treated rats.

CONCLUSION

VC possesses cardio-autonomic nerve protective potential and ameliorates the symptoms of cardiac autonomic neuropathy in type 2 diabetes. The possible mechanisms via which VC exert these effects may be via downregulation of oxidative stress, inflammation and apolipoprotein B.

The Role of Oxidative Stress in Peripheral Neuropathy

Peripheral neuropathy (PN) is a common disease affecting about 5% of the general population after the age of 50. Causes of PN are numerous and include genetic, diabetes, alcohol, vitamin deficiencies, and gluten sensitivity among others. This systematic review aimed to study the association between oxidative stress and PN in an attempt to better understand PN pathogenesis. A computer-based, systematic search was conducted on the PubMed database, and ensuing data from included articles was analyzed and discussed in this review. Sixty-nine papers were eligible and were used for this review. Peripheral neuropathy is associated with an increase of reactive oxygen species and a decrease in endogenous antioxidants. Genetic predisposition to oxidative damage may be a factor. Antioxidant treatment is promising regarding treatment. Though further research is necessary to better understand the underlying mechanism, it is evident that oxidative stress is implicated in the pathogenesis of - or is at least systematically present in - PN.

Thiol/disulfide homeostasis and ischemia modified albumin levels in autoimmune gastritis and their relations with gastric emptying

Background/aim

Autoimmune gastritis is an autoimmune and inflammatory disorder. The aim of this study is to examine dynamic thiol/disulfide homeostasis and ischemia modified albumin levels, and to analyze the association between thiol/disulfide homeostasis and gastric emptying time in autoimmune gastritis.

Materials and methods

Thiol/disulfide homeostasis tests and ischemia modified albumin levels were determined in 50 autoimmune gastritis patients and 53 healthy subjects. Patients with delayed and normal gastric emptying were compared by thiol/disulfide homeostasis tests.

Results

The results showed that native thiol (μmol/L), total thiol (μmol/L), and native thiol/total thiol ratio (%) of the patients with autoimmune gastritis decreased compared to the control group (177.7 ± 34.18 vs. 245.25 ± 33.83, P = 0.001, 227.25 ± 36.78 vs. 284.20 ± 27.19, P = 0.03, and 8.84 ± 1.1 vs. 7.74% ± 1.3%, P = 0.001). In addition, native thiol (μmol/L), total thiol (μmol/L), and native thiol/ total thiol ratio (%) were found to be lower in patients with delayed gastric emptying (198.65 ± 24.27 vs. 167.12 ± 20.51, 241.81 ± 27.14 vs. 213.92 ± 26.35, 8.34 ± 1.29 vs. 7.20 ± 1.83, P = 0.001). Disulfide level, disulfide/native thiol, disulfide/total thiol (P = 0.001) ratios, and ischemia modified albumin levels (ABSU, 0.71 ± 0.08 vs. 0.83 ± 0.07) were found to be higher in autoimmune gastritis patients with delayed gastric emptying (P = 0.001).

Conclusion

The results showed that thiol/disulfide homeostasis in patients with autoimmune gastritis caused an increase in ischemia modified albumin and disulfide whereas a decrease in thiols. An altered thiol/disulfide balance was also observed in patients with delayed gastric emptying. These results suggest that the oxidative process is involved in patients with autoimmune gastritis.

Association between Disturbances in Polyunsaturated Fatty Acid Metabolism and Development of Oxidative Stress during Experimental Diabetes Mellitus

We studied the effect of streptozotocin-induced diabetes mellitus on the level of glycemia and some other indices of lipid metabolism, including fatty acid metabolism and LPO intensity, during the development of diabetes mellitus in rats. Even at the early terms of diabetes development, hypertriglyceridemia and hypercholesterolemia were accompanied by changes in the blood content of fatty acid (at the expense of ω3 and ω6 fatty acids) that persisted throughout the observation period. Intensification of LPO against the background of suppressed activity of antioxidant enzymes and reduced level of ω3 fatty acids attested to the development of oxidative stress. These data attest to antioxidant property of ω3 fatty acids, which is seen from positive correlations between these fatty acids and activity of antioxidant enzymes.

HbA1C Variability Is Strongly Associated With the Severity of Peripheral Neuropathy in Patients With Type 2 Diabetes

Variability in HbA1c is associated with a higher risk of cardiovascular disease and microvascular complications in patients with type 2 diabetes. The present study evaluated the severity of somatic nerve dysfunction at different stages of chronic glycemic impairment, and its correlation with different cardio-metabolic parameters. The study was conducted on 223 patients with type 2 diabetes. We calculated the intrapersonal mean, standard deviation (SD), and coefficient of variation of HbA1c for each patient using all measurements obtained for 3 years prior to the study. Patients were divided into quartiles according to the SD of HbA1c, and we constructed composite scores of nerve conduction as the severity of peripheral neuropathy. Linear regression analysis was performed to evaluate the influence of independent variables on mean composite scores. Those with higher SD-HbA1c had a higher body mass index, mean and index HbA1c, triglyceride and uric acid level, urinary albumin excretion and albumin-creatinine ratio, proportion of insulin therapy, and prevalence of hypertension as the underlying diseases, but lower estimate glomerular filtration rate (eGFR). In addition, those with higher SD-HbA1c showed lower amplitudes and reduced motor nerve conduction velocity in tested nerves, and lower sensory nerve conduction velocity in the sural nerve. Furthermore, those with higher SD-HbA1c had higher composite scores of low extremities. Multiple linear regression analysis revealed that diabetes duration, SD-HbA1c, and eGFR were independently associated with mean composite scores. Based on our results, HbA1c variability plus chronic glycemic impairment is strongly associated with the severity of peripheral neuropathy in patients with type 2 diabetes. Aggressively control blood glucose to an acceptable range and avoid blood glucose fluctuations by individualized treatment to prevent further nerve damage.

Emerging Biomarkers, Tools, and Treatments for Diabetic Polyneuropathy

Diabetic neuropathy, with its major clinical sequels, notably neuropathic pain, foot ulcers, and autonomic dysfunction, is associated with substantial morbidity, increased risk of mortality, and reduced quality of life. Despite its major clinical impact, diabetic neuropathy remains underdiagnosed and undertreated. Moreover, the evidence supporting a benefit for causal treatment is weak at least in patients with type 2 diabetes, and current pharmacotherapy is largely limited to symptomatic treatment options. Thus, a better understanding of the underlying pathophysiology is mandatory for translation into new diagnostic and treatment approaches. Improved knowledge about pathogenic pathways implicated in the development of diabetic neuropathy could lead to novel diagnostic techniques that have the potential of improving the early detection of neuropathy in diabetes and prediabetes to eventually embark on new treatment strategies. In this review, we first provide an overview on the current clinical aspects and illustrate the pathogenetic concepts of (pre)diabetic neuropathy. We then describe the biomarkers emerging from these concepts and novel diagnostic tools and appraise their utility in the early detection and prediction of predominantly distal sensorimotor polyneuropathy. Finally, we discuss the evidence for and limitations of the current and novel therapy options with particular emphasis on lifestyle modification and pathogenesis-derived treatment approaches. Altogether, recent years have brought forth a multitude of emerging biomarkers reflecting different pathogenic pathways such as oxidative stress and inflammation and diagnostic tools for an early detection and prediction of (pre)diabetic neuropathy. Ultimately, these insights should culminate in improving our therapeutic armamentarium against this common and debilitating or even life-threatening condition.

Myeloperoxidase, superoxide dismutase-3, cardiometabolic risk factors, and distal sensorimotor polyneuropathy: The KORA F4/FF4 study

BACKGROUND

Oxidative stress has been proposed as important pathomechanism of cardiometabolic diseases and distal sensorimotor polyneuropathy (DSPN). However, the relevance of biomarkers of oxidative stress has not been investigated in this context. Therefore, this study aimed to assess the association of the prooxidant myeloperoxidase (MPO) and the antioxidant extracellular superoxide dismutase (SOD3) with cardiometabolic risk factors and with prevalence and incidence of DSPN.

METHODS

Cross-sectional analyses comprised 1069 participants (40.3% with prediabetes and 20.5% with type 2 diabetes) of the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4 study (2006-2008), 181 of whom had DSPN at baseline. Prospective analyses included 524 individuals without DSPN at baseline who also participated in the KORA FF4 study (2013-2014), 132 of whom developed DSPN during the 6.5-year follow-up. Serum MPO and SOD3 were measured by ELISA, and their association with cardiometabolic risk factors and DSPN were estimated by using linear and logistic regression analyses.

RESULTS

Higher MPO and SOD levels showed multiple positive associations with cardiometabolic risk factors including age, indices of obesity, insulin resistance, serum lipids, renal dysfunction, and biomarkers of inflammation. Higher MPO levels were associated with prevalent DSPN (fully adjusted OR 1.38 [95% CI 1.10; 1.72] per doubling of MPO). Higher baseline SOD3 levels were related to incident DSPN (age and sex-adjusted OR 2.14 [1.02; 4.48] per doubling of SOD3), which was partially explained by cardiometabolic risk factors.

CONCLUSIONS

Systemic levels of both pro- and antioxidant enzymes appear involved in cardiometabolic risk and development of DSPN.

Metabolic Syndrome and Neuroprotection

Introduction: Over the years the prevalence of metabolic syndrome (MetS) has drastically increased in developing countries as a major byproduct of industrialization. Many factors, such as the consumption of high-calorie diets and a sedentary lifestyle, bolster the spread of this disorder. Undoubtedly, the massive and still increasing incidence of MetS places this epidemic as an important public health issue. Hereon we revisit another outlook of MetS beyond its classical association with cardiovascular disease (CVD) and Diabetes Mellitus Type 2 (DM2), for MetS also poses a risk factor for the nervous tissue and threatens neuronal function. First, we revise a few essential concepts of MetS pathophysiology. Second, we explore some neuroprotective approaches in MetS pertaining brain hypoxia. The articles chosen for this review range from the years 1989 until 2017; the selection criteria was based on those providing data and exploratory information on MetS as well as those that studied innovative therapeutic approaches.

Pathophysiology: The characteristically impaired metabolic pathways of MetS lead to hyperglycemia, insulin resistance (IR), inflammation, and hypoxia, all closely associated with an overall pro-oxidative status. Oxidative stress is well-known to cause the wreckage of cellular structures and tissue architecture. Alteration of the redox homeostasis and oxidative stress alter the macromolecular array of DNA, lipids, and proteins, in turn disrupting the biochemical pathways necessary for normal cell function.

Neuroprotection: Different neuroprotective strategies are discussed involving lifestyle changes, medication aimed to mitigate MetS cardinal symptoms, and treatments targeted toward reducing oxidative stress. It is well-known that the routine practice of physical exercise, aerobic activity in particular, and a complete and well-balanced nutrition are key factors to prevent MetS. Nevertheless, pharmacological control of MetS as a whole and pertaining hypertension, dyslipidemia, and endothelial injury contribute to neuronal health improvement.

Conclusion: The development of MetS has risen as a risk factor for neurological disorders. The therapeutic strategies include multidisciplinary approaches directed to address different pathological pathways all in concert.

Insights on Localized and Systemic Delivery of Redox-Based Therapeutics

Reactive oxygen and nitrogen species are indispensable in cellular physiology and signaling. Overproduction of these reactive species or failure to maintain their levels within the physiological range results in cellular redox dysfunction, often termed cellular oxidative stress. Redox dysfunction in turn is at the molecular basis of disease etiology and progression. Accordingly, antioxidant intervention to restore redox homeostasis has been pursued as a therapeutic strategy for cardiovascular disease, cancer, and neurodegenerative disorders among many others. Despite preliminary success in cellular and animal models, redox-based interventions have virtually been ineffective in clinical trials. We propose the fundamental reason for their failure is a flawed delivery approach. Namely, systemic delivery for a geographically local disease limits the effectiveness of the antioxidant. We take a critical look at the literature and evaluate successful and unsuccessful approaches to translation of redox intervention to the clinical arena, including dose, patient selection, and delivery approach. We argue that when interpreting a failed antioxidant-based clinical trial, it is crucial to take into account these variables and importantly, whether the drug had an effect on the redox status. Finally, we propose that local and targeted delivery hold promise to translate redox-based therapies from the bench to the bedside.

Lower serum extracellular superoxide dismutase levels are associated with polyneuropathy in recent-onset diabetes

Increased oxidative stress is implicated in the pathogenesis of experimental diabetic neuropathy, but translational evidence in recent-onset diabetes is scarce. We aimed to determine whether markers of systemic oxidative stress are associated with diabetic sensorimotor polyneuropathy (DSPN) in recent-onset diabetes. In this cross-sectional study, we measured serum concentrations of extracellular superoxide dismutase (SOD3), thiobarbituric acid reactive substances (TBARS), and reduced glutathione (GSH) in 107 type 1 and 215 type 2 diabetes patients from the German Diabetes Study baseline cohort and 37 glucose-tolerant individuals (controls). DSPN was defined by electrophysiological and clinical criteria (Toronto Consensus, 2011). SOD3 and GSH concentrations were lower in individuals with type 1 and type 2 diabetes compared with concentrations in controls (P<0.0001). In contrast, the TBARS concentration was higher in participants with type 1 diabetes and type 2 diabetes compared with levels in controls (P<0.0001). In addition, the SOD3 concentration was higher in participants with type 1 diabetes compared to concentrations in those with type 2 diabetes (P<0.0001). A low SOD3 concentration was associated with DSPN in individuals with type 1 diabetes (β=-0.306, P=0.002), type 2 diabetes (β=-0.164, P=0.017), and in both groups combined (β=-0.206, P=0.0003). Lower SOD3 concentrations were associated with decreased motor nerve conduction velocity (NCV) in men and, to a lesser degree, with reduced sensory NCV in women with diabetes. In conclusion, several biomarkers of oxidative stress are altered in recent-onset diabetes, with only a lower SOD3 concentration being linked to the presence of DSPN, suggesting a role for reduced extracellular antioxidative defense against superoxide in the early development of DSPN.

Inflammation and oxidative stress in corneal tissue in experimental keratitis due to Fusarium solani: Amelioration following topical therapy with voriconazole and epigallocatechin gallate

Combined antifungal and antioxidant therapy may help to reduce oxidative stress in fungal keratitis. Experimental Fusarium solani keratitis was induced by application of F. solani conidia to scarified cornea (right eye) of 16 rabbits (another four rabbits were negative controls [Group I]). Five days later, F. solani-infected animals began receiving hourly topical saline alone (Group II), voriconazole (10 mg/mL) alone (Group III), epigallocatechin gallate (EGCG, 10 mg/mL) alone (Group IV) or voriconazole and EGCG (Group V). Twenty days post-inoculation, corneal lesions were graded. After animal sacrifice, excised corneas underwent histopathological and microbiological investigations. Corneal tissue levels/activities of interleukin 1 beta (IL-1β) and tumour necrosis factor alpha (TNF-α) gene mRNA transcripts, matrix metalloproteinase (MMP) 2 and 9 proteins, malondialdehyde (MDA) and reduced glutathione (GSH), and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), were also measured. Clinical and histopathological scores (severity of corneal lesions; [P < .05]) and mean levels (P < .05) of IL-1β and TNF-α mRNA transcripts, MMP 2, MMP 9 and MDA were Group II > Groups IV and III > Groups V and I. Mean SOD, CAT, GPx and GSH levels (P < .05) were Group II < Groups IV and III < Groups V and I. Topical voriconazole with EGCG apparently reduces inflammation in experimental F. solani keratitis, as manifested by improved clinical, histological, microbiological and molecular parameters.

Pre-Clinical Study for the Antidiabetic Potential of Selenium Nanoparticles

This research was delineated to explore the efficacy of selenium nanoparticles delivered in liposomes (L-Se) in the mitigation of type-2 diabetes mellitus. Adult female Wistar rats were assigned into four groups: group I, the normal control group in which the rats received normal saline solution orally; group II, the diabetic control group in which the rats were injected intraperitoneally with a single dose of streptozotocin (STZ) for induction of diabetes; group III, the metformin (Met)-treated group in which the diabetic rats were treated orally with Met; and group IV, the L-Se-treated group in which the diabetic rats were treated orally with L-Se. All treatments were delivered for 21 days. Blood and pancreas tissue samples were obtained for biochemical analysis, immunohistochemical examinations, and histopathological investigation. The L-Se-treated group showed significant drop in serum glucose and pancreatic malondialdehyde (MDA), nitric oxide (NO), tumor necrosis factor-α (TNF-α), and prostaglandin F2α (PGF2α) levels associated with significant rise in serum insulin and pancreatic glutathione, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) values, in addition to significant improvement in the immunohistochemical indices (insulin and glucagon). Aforementioned results are appreciated by the histopathological findings of pancreatic tissue. In conclusion, our data have brought about compelling evidence favoring the antidiabetic potency of elemental selenium nanoparticles delivered in liposomes through preservation of pancreatic β cell integrity with consequent increment of insulin secretion and in turn glucose depletion, repression of oxidative stress, potentiation of the antioxidant defense system, and inhibition of pancreatic inflammation.

Plasma Markers of Oxidative Stress in Patients with Gestational Diabetes Mellitus in the Second and Third Trimester

Objective. To determine plasma markers of oxidative stress during the second and third trimester of pregnancy in patients with gestational diabetes mellitus (GDM). Study Design. We conducted a prospective nested case-control study involving 400 pregnant women, 22 of whom developed GDM. As control group, 30 normal pregnant women were chosen randomly. Plasma samples were analyzed for 8-iso-prostaglandin F2α (8-iso-PGF2α), advanced oxidative protein products (AOPPs), protein carbonyl (PCO), glutathione peroxidase-3 (GPX-3), and paraoxonase-1 (PON1) at 16–20 weeks, 24–28 weeks, and 32–36 weeks of gestation. Results. Compared to control subjects, the plasma levels of PCO, AOPPs, and 8-iso-PGF2α were elevated at 16–20 weeks' and 32–36 weeks' gestation in GDM. There was no significant difference in PCO and 8-iso-PGF2α at 24–28 weeks in GDM. GPX-3 was statistically significantly increased at 16–20 weeks and 32–36 weeks in GDM. PON1 reduced in patients with GDM. No significant differences were found at 24–28 and 32–36 weeks between the GDM and control groups. In GDM, PCO, AOPPs, and 8-iso-PGF2α levels were higher and GPX-3 and PON1 levels were lower in the second than the third trimester. Conclusion. Oxidation status increased in GDM, especially protein oxidation, which may contribute to the pathogenesis of GDM.

Photobiomodulation (Laser and LED) on Sternotomy Healing in Hyperglycemic and Normoglycemic Patients Who Underwent Coronary Bypass Surgery with Internal Mammary Artery Grafts: A Randomized, Double-Blind Study with Follow-Up

BACKGROUND AND OBJECTIVE

This study aimed at analyzing the healing effects of low-level laser therapy (LLLT) (λ620 nm, 6 J/cm²) and light-emitting diode (LED) therapy (λ640 nm, 6 J/cm²) on the longitudinal sternotomy incisions of hyperglycemic and normoglycemic patients who underwent coronary artery bypass grafting (CABG).

MATERIALS AND METHODS

120 volunteers were electively submitted to CABG and were randomly allocated into four different groups of equal size (n = 30): control, placebo, laser (λ of 640 nm and spatial average energy fluency [SAEF] of 1.06 J/cm²), and LED (λ of 660 ± 20 nm and SAEF of 0.24 J/cm²). Laser and LED groups were irradiated from the second to eighth day postsurgery, and sternotomy incision was photographically registered. Then, participants were also separated into hyperglycemic and normoglycemic groups, according to their fasting blood glucose test before surgery. Three researchers blindly analyzed the incision photographs to determine hyperemia and wound closure at the first day of hospital discharge (eighth postoperative day).

RESULTS

LLLT and LED groups had similarly less hyperemia and less incision bleeding or dehiscence (p ≤ 0.005) and the outcomes were also analogous between hyperglycemic and normoglycemic patients, which indicates no difference observed in an intragroup analysis (p ≥ 0.05).

CONCLUSIONS

With the present therapy parameters, it may be assumed that both coherent light (laser) and non-coherent light (LED) are effective in promoting sternotomy and healing acceleration, which are evident on the eighth day postsurgery.

Bioactive Compounds and Their Neuroprotective Effects in Diabetic Complications

Hyperglycemia, hyperlipidemia and impaired insulin signaling during the development of diabetes can cause diabetic complications, such as diabetic neuropathy, resulting in significant morbidity and mortality. Although various therapeutics are available for the treatment of diabetic neuropathy, no absolute cure exists, and additional research is necessary to comprehensively understand the underlying pathophysiological pathways. A number of studies have demonstrated the potential health benefits of bioactive compounds, i.e., flavonoids and vitamins, which may be effective as supplementary treatments for diabetes and its complications. In this review, we highlight the most recent reports about the mechanisms of action of bioactive compounds (flavonoids and vitamins) possessing potential neuroprotective properties in diabetic conditions. Additional clinical studies are required to determine the appropriate dose and duration of bioactive compound supplementation for neuroprotection in diabetic patients.

Oxidative stress is associated with decreased heart rate variability in patients with chronic kidney disease

OBJECTIVES

Elevated oxidative stress and reduced heart rate variability (HRV) is prevalent in patients with chronic kidney disease (CKD) and is associated with increased morbidity and mortality. Previous studies have identified a positive association between elevated oxidative stress and autonomic dysfunction, however this relationship has not yet been investigated in the CKD population.

METHODS

Plasma was collected from 78 patients with stage 3-4 CKD (estimated glomerular filtration rate 25-60 ml/min/1.73 m²) for the assessment of oxidative stress, including plasma total F2-isoprostanes, glutathione peroxidase activity and total antioxidant capacity. Time and frequency HRV parameters were measured from a three lead electrocardiogram.

RESULTS

Participants with elevated F2-isoprostanes had reduced HRV compared to patients with normal levels of F2-isoprostanes. A number of HRV parameters were found to be inversely correlated with F2-isoprostanes in all CKD patients, including SDNN (r = -0.337; P < 0.01), VLF (r = -0.281, P = 0.01), LF (r = -0.315, P < 0.01) and total power (r = -0.288, P = 0.01). Multiple linear regression found F2-isoprostanes to be an independent predictor of SDNN (r² = 0.287, β = -0.272, P = 0.01).

DISCUSSION

Oxidative stress is significantly and independently associated with HRV in patients with CKD. Identifying oxidative stress in the pathogenesis of autonomic dysfunction may help target therapeutic strategies.

Low-Level Laser and Light-Emitting Diode Therapy for Pain Control in Hyperglycemic and Normoglycemic Patients Who Underwent Coronary Bypass Surgery with Internal Mammary Artery Grafts: A Randomized, Double-Blind Study with Follow-Up

OBJECTIVE

This study aimed to evaluate the efficacy of low-level laser therapy (LLLT) and light-emitting diodes (LEDs) for reducing pain in hyperglycemic and normoglycemic patients who underwent coronary artery bypass surgery with internal mammary artery grafts.

METHODS

This study was conducted on 120 volunteers who underwent elective coronary artery bypass graft (CABG) surgery. The volunteers were randomly allocated to four different groups of equal size (n = 30): control, placebo, LLLT [λ = 640 nm and spatial average energy fluence (SAEF) = 1.06 J/cm(2)], and LED (λ = 660 ± 20 nm and SAEF = 0.24 J/cm(2)). Participants were also divided into hyperglycemic and normoglycemic subgroups, according to their fasting blood glucose test result before surgery. The outcome assessed was pain during coughing by a visual analog scale (VAS) and the McGill Pain Questionnaire.

RESULTS

The patients were followed for 1 month after the surgery. The LLLT and LED groups showed a greater decrease in pain, with similar results, as indicated by both the VAS and the McGill questionnaire (p ≤ 0.05), on the 6th and 8th postoperative day compared with the placebo and control groups. The outcomes were also similar between hyperglycemic and normoglycemic patients. One month after the surgery, almost no individual reported pain during coughing.

CONCLUSIONS

LLLT and LED had similar analgesic effects in hyperglycemic and normoglycemic patients, better than placebo and control groups.

Motor nerve conduction velocity is affected in segmental vitiligo lesional limbs

To evaluate the effects of segmental vitiligo (SV) on nerve conduction velocity (NCV) in different nerves, we compared the patient's lesional side of their body to the contralateral normal side. The 106 participants were selected from outpatients visiting the dermatological clinics of Huashan Hospital, Fudan University, from November 2011 to March 2014. NCVs were measured on the limbs and the face, including both motor and sensory nerves. The parameters for NCVs included motor nerve conduction velocity (MCV) and its distal conduction latency, sensory nerve conduction velocity, sensory nerve action potentials amplitude, and compound muscle action potential amplitude. MCV on the limbs was compromised by SV state, which was significantly slower on the lesional side of the body compared with the normal contralateral side (P = 0.006). Furthermore, SV at the stable stage significantly impaired MCV compared with the SV at progressive stage. There was no significant difference in the other parameters of NCV between lesional and normal sides of the body. Compound muscle action potentials in the face did not differ between lesional and healthy sides. Motor nerves in the limbs were compromised by SV, particularly when the disease was at the stable stage.

Diabetic Polyneuropathy in Type 2 Diabetes Mellitus: Inflammation, Oxidative Stress, and Mitochondrial Function

Diabetic polyneuropathy (DPN) is defined as peripheral nerve dysfunction. There are three main alterations involved in the pathologic changes of DPN: inflammation, oxidative stress, and mitochondrial dysfunction. Inflammation induces activation of nuclear factor kappa B, activator protein 1, and mitogen-activated protein kinases. Oxidative stress induced by hyperglycemia is mediated by several identified pathways: polyol, hexosamine, protein kinase C, advanced glycosylation end-products, and glycolysis. In addition, mitochondrial dysfunction accounts for most of the production of reactive oxygen and nitrosative species. These free radicals cause lipid peroxidation, protein modification, and nucleic acid damage, to finally induce axonal degeneration and segmental demyelination. The prevalence of DPN ranges from 2.4% to 78.8% worldwide, depending on the diagnostic method and the population assessed (hospital-based or outpatients). Risk factors include age, male gender, duration of diabetes, uncontrolled glycaemia, height, overweight and obesity, and insulin treatment. Several diagnostic methods have been developed, and composite scores combined with nerve conduction studies are the most reliable to identify early DPN. Treatment should be directed to improve etiologic factors besides reducing symptoms; several approaches have been evaluated to reduce neuropathic impairments and improve nerve conduction, such as oral antidiabetics, statins, and antioxidants (alpha-lipoic acid, ubiquinone, and flavonoids).

The lung endothelin system: a potent therapeutic target with bosentan for the amelioration of lung alterations in a rat model of diabetes mellitus

PURPOSE

The aim of this study is to show the effect of a new mechanism on endothelin (ET) receptors in the physiopathology of diabetes-related pulmonary injury. We tested the hypothesis that dual ET-1 receptor antagonism via bosentan can reverse diabetes-induced lung injury.

METHODS

The rats (24 male) were separated into four groups: group 1 (HEALTHY): Control group; group 2 (DM): Streptozotocin 60 mg/kg (i.p.); group 3 (DM + BOS-1): Diabetes + bosentan 50 mg/kg per-os; group 4 (DM + BOS-2): Diabetes + bosentan 100 mg/kg per-os. The bosentan treatment was initiated immediately after the onset of STZ-induced diabetes and continued for 6 weeks.

RESULTS

In the treatment group, SOD activity was significantly increased, although GSH and MDA levels and TNF-α and TGF-β gene expression were decreased. Bosentan 50 mg/kg and bosentan 100 mg/kg showed a significantly down-regulatory effect on ET-1, ET-A, and ET-B mRNA expression.

CONCLUSIONS

In conclusion, increased endothelin levels in the lung associated with diabetes may be one cause of endothelial dysfunction, cytokine increase, and oxidant/antioxidant imbalance in the pathogenesis of complications that may develop during diabetes. With its multiple effects, bosentan therapy may be an effective option against complications that may develop in association with diabetes.

Significance of functional GRP78 polymorphisms in predicting the onset of type 2 diabetic peripheral neuropathy in Chinese population

OBJECTIVE

The objective of this study is to investigate the significance of functional GRP78 polymorphisms in predicting the risk of type 2 diabetic peripheral neuropathy in Chinese population.

METHODS

Between the years of 2006 and 2010, a total of 295 definitely diagnosed type 2 diabetes mellitus (T2DM) patients were included into our study cohort and followed for 3 years. At baseline and annual re-examinations, the patients underwent physical examinations, laboratory tests and evaluation of Michigan diabetic neuropathy score (MDNS). Age, gender, disease course, waist-hip circumference ratio (WHR), body mass index (BMI), triglycerine (TG), total cholesterol (Tch), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), glycosylated haemoglobin (HbA1c), uric acid elimination rate (UAER) and uric acid (UA) were recorded and GRP78 polymorphisms were tested by direct sequencing. The prognostic significance of GRP78 polymorphisms were analysed using monovariate and multivariate logistic regression.

RESULTS

Three years after baseline, 32.9% (97/295) of the T2DM patients had suffered the development of diabetic peripheral neuropathy and GRP78 rs391957 promoter polymorphism is a significant risk factor for the onset of type 2 diabetic peripheral neuropathy. In monovariate regression model, the OR values of GRP78 rs391957 promoter polymorphism were 2.233 (C/T) and 2.734 (T/T). As for the model calibrated with demographic and laboratory indexes, the OR values were, respectively, 2.124 (C/T) and 2.423 (T/T).

CONCLUSION

Our study suggested that the GRP78 rs391957 promoter polymorphism is a potential risk factor for type 2 diabetic peripheral neuropathy.

Antioxidant strategies in the management of diabetic neuropathy

Chronic hyperglycaemia (an abnormally high glucose concentration in the blood) resulting from defects in insulin secretion/action, or both, is the major hallmark of diabetes in which it is known to be involved in the progression of the condition to different complications that include diabetic neuropathy. Diabetic neuropathy (diabetes-induced nerve damage) is the most common diabetic complication and can be devastating because it can lead to disability. There is an increasing body of evidence associating diabetic neuropathy with oxidative stress. Oxidative stress results from the production of oxygen free radicals in the body in excess of its ability to eliminate them by antioxidant activity. Antioxidants have different mechanisms and sites of actions by which they exert their biochemical effects and ameliorate nerve dysfunction in diabetes by acting directly against oxidative damage. This review will examine different strategies for managing diabetic neuropathy which rely on exogenous antioxidants.

Oxidative stress predicts progression of peripheral and cardiac autonomic nerve dysfunction over 6 years in diabetic patients

Oxidative stress is implicated in the pathogenesis of experimental diabetic neuropathy, but prospective studies in diabetic patients are lacking. We aimed to evaluate whether the plasma levels of various biomarkers of oxidative stress predict the progression of diabetic neuropathy and mortality over 6 years. We followed 89 diabetic patients aged 54 ± 14 years (59 % with polyneuropathy), 72 of whom underwent nerve function reassessment after 6.2 ± 0.8 years, whereas 17 died after 4.2 ± 1.0 years. Plasma markers of oxidative stress at baseline included superoxide anion, hypochlorous acid, peroxynitrite, 8-iso-prostaglandin F2α, vitamin E/lipid ratio, and vitamin C. Neuropathy was assessed by symptoms and deficits, motor and sensory nerve conduction velocity (MNCV, SNCV), vibration perception thresholds (VPT), thermal detection thresholds, and heart rate variability (HRV). Despite a reduction in HbA1c by 1.4 ± 1.6 % (p < 0.001), median SNCV, sural SNCV, peroneal MNCV, malleolar VPT, and warm TDT deteriorated after 6 years (all p < 0.05). In multivariate models, increased superoxide generation was associated with a decline in median SNCV (β = -0.997; p = 0.036) and deterioration in HRV at rest (OR 1.63 [95 % CI 1.09-2.44]; p = 0.017) over 6 years. Low vitamin E/lipid ratio tended to predict a decrease in peroneal MNCV (β = 0.781; p = 0.057) and an increase in malleolar VPT (β = -0.725; p = 0.077). Plasma superoxide generation was associated with an increased risk of mortality (HR 23.2 [95 % CI 1.05-513]; p = 0.047). In conclusion, increased plasma superoxide generation predicted the decline in sensory and cardiac autonomic nerve function and mortality over 6 years in diabetic patients, but larger studies are required for confirmation.