Brazilian Journal of Medical and Biological Research
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Open Access journal
ISSN (Print) 0100-879X - ISSN (Online) 1414-431X
Published by SciELO [717 journals]
- Decreased platelet responsiveness to clopidogrel correlates with CYP2C19
and PON1 polymorphisms in atherosclerotic patients
Abstract: Clopidogrel and aspirin are the most commonly used medications worldwide for dual antiplatelet therapy after percutaneous coronary intervention. However, clopidogrel hyporesponsiveness related to gene polymorphisms is a concern. Populations with higher degrees of genetic admixture may have increased prevalence of clopidogrel hyporesponsiveness. To assess this, we genotyped CYP2C19, ABCB1, and PON1 in 187 patients who underwent percutaneous coronary intervention. Race was self-defined by patients. We also performed light transmission aggregometry with adenosine diphosphate (ADP) and arachidonic acid during dual antiplatelet therapy. We found a significant difference for presence of the CYP2C19*2 polymorphism between white and non-white patients. Although 7% of patients had platelet resistance to clopidogrel, this did not correlate with any of the tested genetic polymorphisms. We did not find platelet resistance to aspirin in this cohort. Multivariate analysis showed that patients with PON1 and CYP2C19 polymorphisms had higher light transmission after ADP aggregometry than patients with native alleles. There was no preponderance of any race in patients with higher light transmission aggregometry. In brief, PON1 and CYP2C19 polymorphisms were associated with lower clopidogrel responsiveness in this sample. Despite differences in CYP2C19 polymorphisms across white and non-white patients, genetic admixture by itself was not able to identify clopidogrel hyporesponsiveness.
- Time course of changes in heart rate and blood pressure variability in
rats with myocardial infarction
Abstract: Our aim was to determine the time course of changes in autonomic balance in the acute (1 and 3 days), sub-acute (7 days) and chronic (28 days) phases of myocardial infarction (MI) in rats. Autonomic balance was assessed by temporal and spectral analyses of blood pressure variability (BPV) and heart rate variability (HRV). Pulsatile blood pressure (BP) recordings (30 min) were obtained in awake and unrestrained male Wistar rats (N = 77; 8-10 weeks old) with MI (coronary ligature) or sham operation (SO). Data are reported as means±SE. The high frequency (HF) component (n.u.) of HRV was significantly lower in MI-1- (P<0.01) and MI-3-day rats (P<0.05) than in their time-control groups (SO-1=68±4 vs MI-1=35.3±4.3; SO-3=71±5.8 vs MI-3=45.2±3.8), without differences thereafter (SO-7=69.2±4.8 vs MI-7=56±5.8; SO-28=73±4 vs MI-28=66±6.6). A sharp reduction (P<0.05) of BPV (mmHg2) was observed in the first week after MI (SO-1=8.55±0.80; SO-3=9.11±1.08; SO-7=7.92±1.10 vs MI-1=5.63±0.73; MI-3=5.93±0.30; MI-7=5.30±0.25). Normal BPV, however, was observed 4 weeks after MI (SO-28=8.60±0.66 vs MI-28=8.43±0.56 mmHg2; P>0.05). This reduction was mainly due to attenuation of the low frequency (LF) band of BPV in absolute and normalized units (SO-1=39.3±7%; SO-3=55±4.5%; SO-7=46.8±4.5%; SO-28=45.7±5%; MI-1=13±3.5%; MI-3=35±4.7%; MI-7=25±2.8%; MI-28=21.4±2.8%). The results suggest that the reduction in HRV was associated with decrease of the HF component of HRV suggesting recovery of the vagal control of heartbeats along the post-infarction healing period. The depression of BPV was more dependent on the attenuation of the LF component, which is linked to the baroreflex modulation of the autonomic balance.
- Survival benefits of interferon-based therapy in patients with recurrent
hepatitis C after orthotopic liver transplantation
Abstract: Recurrent hepatitis C after orthotopic liver transplantation (OLT) is universal and can lead to graft failure and, consequently, reduced survival. Hepatitis C treatment can be used to prevent these detrimental outcomes. The aim of this study was to describe rates of hepatitis C recurrence and sustained virological response (SVR) to interferon-based treatment after OLT and its relationship to survival and progression of liver disease through retrospective analysis of medical records of 127 patients who underwent OLT due to cirrhosis or hepatocellular carcinoma secondary to chronic hepatitis C between January 2002 and December 2013. Fifty-six patients were diagnosed with recurrent disease, 42 started interferon-based therapy and 37 completed treatment. Demographic, treatment- and outcome-related variables were compared between SVR and non-responders (non-SVR). There was an overall 54.1% SVR rate with interferon-based therapies. SVR was associated with longer follow-up after treatment (median 66.5 vs 37 months for non-SVR, P=0.03) and after OLT (median 105 vs 72 months, P=0.074), and lower rates of disease progression (15 vs 64.7%, P=0.0028) and death (5 vs 35.3%, P=0.033). Regardless of the result of therapy (SVR or non-SVR), there was a significant difference between treated and untreated patients regarding the occurrence of death (P<0.001) and months of survival (P<0.001). Even with suboptimal interferon-based therapies (compared to the new direct-acting antivirals) there is a 54.1% SVR rate to treatment. SVR is associated with improved survival and reduced risks of clinical decompensation, loss of the liver graft and death.
- Angiotensin-(1-7) relieved renal injury induced by chronic intermittent
hypoxia in rats by reducing inflammation, oxidative stress and fibrosis
Abstract: We aimed to study the renal injury and hypertension induced by chronic intermittent hypoxia (CIH) and the protective effects mediated by angiotensin 1-7 [Ang(1-7)]. We randomly assigned 32 male Sprague-Dawley rats (body weight 180-200 g) to normoxia control, CIH, Ang(1-7)-treated normoxia, and Ang(1-7)-treated CIH groups. Systolic blood pressure (SBP) was monitored at the start and end of each week. Renal sympathetic nerve activity (RSNA) was recorded. CTGF and TGF-β were detected by immunohistochemistry and western blotting. Tissue parameters of oxidative stress were also determined. In addition, renal levels of interleukin-6, tumor necrosis factor-α, nitrotyrosine, and hypoxia-inducible factor-1α were determined by immunohistochemistry, immunoblotting, and ELISA. TUNEL assay results and cleaved caspase 3 and 12 were also determined. Ang(1-7) induced a reduction in SBP together with a restoration of RSNA in the rat model of CIH. Ang(1-7) treatment also suppressed the production of reactive oxygen species, reduced renal tissue inflammation, ameliorated mesangial expansion, and decreased renal fibrosis. Thus, Ang(1-7) treatment exerted renoprotective effects on CIH-induced renal injury and was associated with a reduction of oxidative stress, inflammation and fibrosis. Ang(1-7) might therefore represent a promising therapy for obstructive sleep apnea-related hypertension and renal injury.
- A broad pH range and processive chitinase from a metagenome library
Abstract: Chitinases are hydrolases that degrade chitin, a polymer of N-acetylglucosamine linked β(1-4) present in the exoskeleton of crustaceans, insects, nematodes and fungal cell walls. A metagenome fosmid library from a wastewater-contaminated soil was functionally screened for chitinase activity leading to the isolation and identification of a chitinase gene named metachi18A. The metachi18A gene was subcloned and overexpressed in Escherichia coli BL21 and the MetaChi18A chitinase was purified by affinity chromatography as a 6xHis-tagged fusion protein. The MetaChi18A enzyme is a 92-kDa protein with a conserved active site domain of glycosyl hydrolases family 18. It hydrolyses colloidal chitin with an optimum pH of 5 and temperature of 50°C. Moreover, the enzyme retained at least 80% of its activity in the pH range from 4 to 9 and 98% at 600 mM NaCl. Thin layer chromatography analyses identified chitobiose as the main product of MetaChi18A on chitin polymers as substrate. Kinetic analysis showed inhibition of MetaChi18A activity at high concentrations of colloidal chitin and 4-methylumbelliferyl N,N′-diacetylchitobiose and sigmoid kinetics at low concentrations of colloidal chitin, indicating a possible conformational change to lead the chitin chain from the chitin-binding to the catalytic domain. The observed stability and activity of MetaChi18A over a wide range of conditions suggest that this chitinase, now characterized, may be suitable for application in the industrial processing of chitin.
- Ferulic acid lowers body weight and visceral fat accumulation via
modulation of enzymatic, hormonal and inflammatory changes in a mouse
model of high-fat diet-induced obesity
Abstract: Previous studies have reported on the glucose and lipid-lowering effects of ferulic acid (FA) but its anti-obesity potential has not yet been firmly established. This study investigated the possible anti-obesitogenic effects of FA in mice fed a high-fat diet (HFD) for 15 weeks. To assess the antiobesity potential of FA, 32 male Swiss mice, weighing 20–25 g (n=6–8 per group) were fed a normal diet (ND) or HFD, treated orally or not with either FA (10 mg/kg) or sibutramine (10 mg/kg) for 15 weeks and at the end of this period, the body weights of animals, visceral fat accumulation, plasma levels of glucose and insulin hormone, amylase and lipase activities, the satiety hormones ghrelin and leptin, and tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCH-1) were analyzed. Results revealed that FA could effectively suppress the HFD-associated increase in visceral fat accumulation, adipocyte size and body weight gain, similar to sibutramine, the positive control. FA also significantly (P<0.05) decreased the HFD-induced elevations in serum lipid profiles, amylase and lipase activities, and the levels of blood glucose and insulin hormone. The markedly elevated leptin and decreased ghrelin levels seen in HFD-fed control mice were significantly (P<0.05) reversed by FA treatment, almost reaching the values seen in ND-fed mice. Furthermore, FA demonstrated significant (P<0.05) inhibition of serum levels of inflammatory mediators TNF-α, and MCH-1. These results suggest that FA could be beneficial in lowering the risk of HFD-induced obesity via modulation of enzymatic, hormonal and inflammatory responses.
- Propofol inhibits lung cancer cell viability and induces cell apoptosis by
upregulating microRNA-486 expression
Abstract: Propofol is a frequently used intravenous anesthetic agent. Recent studies show that propofol exerts a number of non-anesthetic effects. The present study aimed to investigate the effects of propofol on lung cancer cell lines H1299 and H1792 and functional role of microRNA (miR)-486 in these effects. H1299 and/or H1792 cells were treated with or without propofol and transfected or not with miR-486 inhibitor, and then cell viability and apoptosis were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry. The expression of miR-486 was determined by quantitative real-time polymerase chain reaction (qRT-PCR) with or without propofol treatment. Western blot was performed to analyze the protein expression of Forkhead box, class O (FOXO) 1 and 3, Bcl-2 interacting mediator of cell death (Bim), and pro- and activated caspases-3. Results showed that propofol significantly increased the miR-486 levels in both H1299 and H1792 cells compared to untreated cells in a dose-dependent manner (P<0.05 or P<0.01). Propofol statistically decreased cell viability but increased the percentages of apoptotic cells and protein expressions of FOXO1, FOXO3, Bim, and pro- and activated caspases-3; however, miR-486 inhibitor reversed the effects of propofol on cell viability, apoptosis, and protein expression (P<0.05 or P<0.01). In conclusion, propofol might be an ideal anesthetic for lung cancer surgery by effectively inhibiting lung cancer cell viability and inducing cell apoptosis. Modulation of miR-486 might contribute to the anti-tumor activity of propofol.