Evaluation of the in vitro interference of bilirubin and lipids in the measurement of the plasma glutathione reductase activity.

BACKGROUND: The pre-analytical phase is the most vulnerable to errors, and some of the most common interferents in laboratory routine are bilirubin and lipemia. Therefore, the aim of this study was to evaluate the in vitro interference of bilirubin and lipids in the measurement of the activity of glutathione reductase (GR) in plasma samples. METHODS: The evaluation of the in vitro interference of bilirubin was performed by addition of bilirubin to a plasma pool at the following final concentrations: 0.9, 1.9, 3.8, 7.5, 15, and 30 mg/dL. The turbidity of lipemia was simulated by the addition of Intralipid to the plasma pool at the following final concentrations: 0.67, 1.25, 2.5, 5, and 10 mg/dL. GR activity was measured on a Cobas MIRA automated analyzer. RESULTS: Plasma GR activity was significantly affected by bilirubin and lipids. At the concentrations of 0.9 to 30 mg/dL of bilirubin added, the decrease of GR activity ranged between 22.9 to 45.4%. At the concentrations of 0.67 to 10 mg/dL of Intralipid added, the decrease of GR activity ranged between 22.4 to 36.5%. CONCLUSIONS: The addition of bilirubin and lipids in plasma samples interferes negatively in the measurement of GR activity, since GR values are reduced in the presence of these in vitro interferents.

Analysis of oral mucosa of users of crack through micronucleus technique.

BACKGROUND: The high consumption of crack has become a serious public health problem. The properties of this drug as well as the effects caused in the body have been approached in different research studies. However, there is no knowledge about the carcinogen level this substance can cause to the user. The presence of micronuclei as biomarkers of genotoxic action reflects the degree of cellular exposure to carcinogens. Considering this fact, the following research aimed to assess the frequency of micronuclei in the oral mucosa of those chemically dependent on crack. METHODS: The sample consisted of buccal mucosa cells from 10 controls, non-smokers, and non-users of drugs and 10 individuals chemically dependent on crack admitted to a hospital. For cell staining, Feulgen technique was applied. RESULTS: Of the 1000 cells analyzed for each sample, the exposed group had an average of 4.3 micronuclei, presenting significant difference (p < 0.01) when compared with the control group, which averaged 0.1 micronuclei. Regarding pictotic cells, the exposed group is also significantly different from the control group (p < 0.01). The karyorrhexis is the nuclear change with the greatest difference between the two groups. It has an average of 347.9 cells undergoing apoptosis for the exposed group, while the control group presented 34.4 cells, obtaining a significant difference, p < 0.001. CONCLUSIONS: The results assessed by micronucleus technique suggested that crack together with other factors associated with the drug might be linked to an increased incidence of micronuclei.

Plasma malondialdehyde levels and risk factors for the development of chronic complications in type 2 diabetic patients on insulin therapy.

BACKGROUND: We assessed plasma malondialdehyde (MDA) levels as a biomarker of lipid peroxidation in type 2 diabetic patients on insulin therapy. Associations among MDA levels and some risk factors for the development of chronic complications of diabetes were also evaluated. METHODS: MDA, fasting glucose, fructosamine, urinary albumin, total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, creatinine, uric acid, serum albumin, lactate, high sensitive C reactive protein (hsCRP), and vitamin E were measured in 53 type 2 diabetic patients and 26 healthy subjects. RESULTS: MDA levels were higher in type 2 diabetes insulin users (12.8 +/- 3.0 micromol/L) and type 2 diabetes no insulin users (10.3 +/- 2.1 micromol/L) compared to control subjects (8.2 +/- 2.1 micromol/L). Fasting glucose, fructosamine, urinary albumin, and hsCRP were higher in all type 2 diabetic patients compared to controls. Significant correlations were observed between MDA and fasting glucose (r = 0.685, p < 0.001), fructosamine (r = 0.526, p < 0.001), urinary albumin (r = 0.516, p < 0.001), and the duration of type 2 diabetes (r = 0.401, p = 0.005). CONCLUSIONS: MDA levels increased in type 2 diabetes, especially in patients on insulin therapy. Chronic hyperglycemia and other biomarkers, such as urinary albumin, were correlated with MDA levels, suggesting the involvement of lipid peroxidation in the pathogenesis of diabetes complications.

Relationship between oxidative stress and pathological findings in abomasum of infected lambs by Haemonchus contortus.

The aim of this study was to evaluate the nitric oxide (NO) levels, and oxidative and antioxidant markers of lambs experimentally and naturally infected by Haemonchus contortus, and its relation to lesions in the abomasum. For experimental study, a total of 14 healthy lambs were divided into two groups with seven animals each. Group A represented the uninfected animals (control), and Group B was formed by infected animals with 15,000 larvae of H. contortus. Blood was collected on days 15, 45, and 75 post-infection (PI) to obtain serum for biochemical analysis: lactate dehydrogenase (LDH), nitrite/nitrate (NOx), advanced oxidation protein products (AOPP), and ferric reducing ability of plasma (FRAP). Parasitological stool examination (eggs per gram of feces--EPG) was performed on days 15, 45, and 75 PI to verify the evolution of the infection. On day 15 PI EPG was negative, but on days 45 and 75 PI the EPG was positive for animals from Group B. In the three periods evaluated it was observed an increase of LDH levels in serum of lambs infected with gastrointestinal nematodes, but on the other hand NOx levels were reduced on the same periods in infected animals. The AOPP and FRAP levels did not differ between groups on days 15 and 45 PI, but increased significantly on day 75 PI in infected lambs. The same variables were studied in 10 lambs naturally infected with helminths, where more than 97% corresponded to H. contortus (hematocrit and EPG values were 18.8 ± 2.5% and 7120 ± 2940, respectively). Similar to the experimental study, the levels of NOx reduced, and the levels of LDH, FRAP, and AOPP increased in serum of this animal associated inflammatory infiltrate in the mucosa of the abomasum. Therefore, during the infection by H. contortus it was observed alterations in oxidative markers, indicators of cell lesion confirmed by histological examination of the abomasum, and consequently there were changes in antioxidant levels, with the purpose of cell protection. We also conclude that helminth infection interferes with the nitric oxide metabolism.

Increase nitric oxide and oxidative stress in dogs experimentally infected by Ehrlichia canis: effect on the pathogenesis of the disease.

The aim of this study was to evaluate nitric oxide levels, lipid peroxidation, protein oxidation and glutathione reductase activity in serum of dogs experimentally infected by Ehrlichia canis. Banked serum samples of dogs divided into two groups were used: negative control (n=5) and infected by E. canis (n=5). The concentration of nitrite/nitrate (NOx), lipid peroxidation (TBARS), advanced oxidation protein products (AOPP), and glutathione reductase (GR) activity in sera were evaluated. Samples were collected on days 0, 3, 6, 18 and 30 post-infection (PI). NOx and TBARS levels were significantly (P<0.05) higher in the infected group at 18 and 30 days PI, as well as AOPP levels at 30 days PI when compared to samples from control group. The GR activity was significant (P<0.05) increased in serum of dogs infected by E. canis on days 18 and 30 PI. Based on the increased levels of NOx, TBARS, AOPP and GR activity we concluded that dogs experimentally infected by E. canis develop a state of redox imbalance and that these changes might be involved in the pathophysiology of the disease.