Oxidative DNA damage is associated with inflammatory response, insulin resistance and microvascular complications in type 2 diabetes.

Urinary markers of nucleic acid oxidation may be useful biomarkers in diabetes. It has been demonstrated that T2DM patients have an increased level of oxidative DNA damage; however, it is unclear whether increased DNA damage may be related to a greater degree of inflammation and insulin resistance. Thus, the aim of this present study was to investigate the relation of the impact of oxidative DNA damage, assessed by urinary 8-OHdG, on the levels of inflammatory cytokines, as well as insulin resistance. In addition, we also investigated the diagnostic ability of urinary 8-OHdG in the identification of microvascular complications in T2DM.A case-control study, enrolling 22 healthy controls and 54 subjects with T2DM, was performed to evaluate the relation between oxidative DNA damage and interleukin-6 (IL-6), IL-1,tumor necrosis factor-alpha (TNF-α), IL-10, and Homeostasis Model Assessment (HOMA-IR) index. T2DM patients presented higher urinary 8-OHdG, IL-6, IL-1, TNF-α levels and HOMA-IR, and lower IL-10 levels than control subjects. Moreover, urinary 8-OHdG levels were significantly higher in the group T2DM with microvascular complications when compared to the without complications. The areas under the curve for urinary 8-OHdG and urinary albumin were, respectively, 0.836 (P<0.001) and 0.786 (P=0.002). Thus, urinary 8-OHdG has a slightly higher ability to discriminate microvascular complications in T2DM compared with urinary albumin. It was also demonstrated that T2DM patients with higher median of urinary 8-OHdG had significantly elevated levels of IL-6, TNF-α and HOMA-IR, and decreased IL-10 levels. Our findings showed that T2DM patients with higher urinary 8-OHdG levels showed a greater inflammatory degree and higher insulin resistance. It is possible to speculate that T2DM patients present a cascade of events as increasing metabolic abnormalities such as insulin resistance and inflammatory activation, as well as increased ROS generation factors that may contribute directly to greater oxidative DNA damage.

Oxidative stress in dogs with multicentric lymphoma: Effect of chemotherapy on oxidative and antioxidant biomarkers.

INTRODUCTION: Lymphoma is one of the most common types of cancer in dogs, characterized by the proliferation of lymphoid cells. The treatment of this type of cancer is usually based on drugs with high toxicity, which can cause severe side effects. OBJECTIVES: Therefore, the aim of this study was to measure the levels of advanced oxidation protein products (AOPP), thiobarbituric acid reactive substances (TBARS), and ferric reducing antioxidant power (FRAP) in dogs with multicentric lymphoma before and after chemotherapy. METHODS: For this purpose, serum samples of 25 dogs diagnosed with multicentric lymphoma and 15 healthy dogs were used. The animals were exposed to CHOP chemotherapy (cyclophosphamide, vincristine, doxorubicin, and prednisone) and serum samples were collected 5 weeks after treatment. RESULTS: High levels of TBARS, AOPP, and FRAP were observed in sera of dogs with multicentric lymphoma when compared to healthy dogs (P < 0.01), and even higher levels (TBARS and AOPP) were found after chemotherapy i.e. treatment exacerbated the oxidative stress levels. On the other hand, FRAP levels did not differ statistically between animals with lymphoma before and after treatment (P > 0.05). Exacerbated oxidative stress was observed in dogs with multicentric lymphoma Group II (Stage IV-V: involvement of lymph nodes and organs) compared to those in Group I (Stage I-III: only affected lymph nodes) of the disease, as well as the dogs with clinical signs and T immunophenotype. Another important result was observed after chemotherapy, where FRAP levels were higher in dogs that showed complete disease remission compared to animals with progressive disease. CONCLUSIONS: Therefore, dogs with lymphoma showed protein oxidation and lipid peroxidation, as well as increased total antioxidants before and after chemotherapy compared to the control group.

Oxidative stress and inflammatory response biomarkers in dogs with mammary carcinoma.

Mammary carcinoma is the most common cancer that affects dogs, and in many cases it leads to death. Thus, given the importance of this disease, to clarify its pathogenesis is an important measure. In this sense, the aim of this study was to investigate the levels of cytokines and nitric oxide (NO), oxidative and antioxidant status, as well as the activity of adenosine deaminase (ADA) and butyrylcholinesterase (BChE) in dogs diagnosed with mammary carcinoma. With this purpose, thirty-three (33) serum samples from female dogs with histopathological diagnosis of mammary carcinoma, without evidence of metastasis, were used (group B). The material was classified based on the degree of malignancy, as follows: subgroup B1 (low-grade malignancy; n=26) and subgroup B2 (high grade of malignancy; n=7). Serum samples from healthy females (group A; n=10) were used as negative control. Our results showed that levels of cytokines (TNF-α, INF-γ, IL-1, and IL-6), NOx (nitrite/nitrate), AOPP (protein oxidation), and FRAP (antioxidant power) were significantly (P<0.05) increased in dogs with mammary carcinoma (group B), when compared with group A. On the other hand, ADA activity was significantly decreased (P<0.05) in both subgroups B1 and B2, when compared with group A. BChE activity, however, was reduced (P<0.05) only in subgroup B2 when compared with group A and subgroup B1. Unlike other variables, NO, AOPP, and IFN-γ were influenced by the degree of tumor malignancy, i.e., their levels were even higher in subgroup B2. Therefore, based on these results, we can conclude that all variables investigated are related to the pathogenesis of this disease, since they were altered in dogs with mammary tumor. Additionally, we suggest that ADA activity had an anti-inflammatory effect on these tumor samples, probably in order to modulate the inflammatory response.

Association between DNA strand breakage and oxidative, inflammatory and endothelial biomarkers in type 2 diabetes.

Evidence has been presented recently that type 2 diabetes patients have an increased level of DNA damage. This DNA damage could be associated with oxidative, inflammatory, and endothelial biomarkers and could represent a possible indication of injury in the endothelium and induction of inflammation in type 2 diabetes. To confirm this possible association, DNA strand breakage was evaluated by use of the comet assay and its association with oxidative, inflammatory, and endothelial biomarkers in type 2 diabetes patients. A case-control study (30 healthy controls and 32 subjects with type 2 diabetes) was performed to evaluate the association between DNA damage and NOx (nitrate/nitrite), interleukin-6 (IL-6), urinary albumin, fasting glucose, and glycated hemoglobin (HbA(1c)) levels. Type 2 diabetes patients presented higher DNA damage than control subjects, higher levels of IL-6 and urinary albumin, and lower NOx. Significant correlations between DNA damage and NOx (r=-0.303, p=0.016), IL-6 (r=0.845, p<0.001), urinary albumin (r=0.496, p<0.001), fasting glucose (r=0.449, p<0.001), and HbA(1c) (r=0.575, p<0.001) were reported. Our findings showed an increase of DNA damage in type 2 diabetes especially in those patients with poor glycemic control and associations among NOx, IL-6 and urinary albumin levels with DNA damage.