MTHFR Polymorphisms and Cardiac Parameters in Patients with Diabetic Retinopathy

BACKGROUND

Diabetes Mellitus (DM) is directly associated with cardiovascular dysfunctions and microvascular complications, such as diabetic retinopathy (DR). The association between DR and increased risks of developing cardiovascular diseases has been described. The low activity of the Methylenetetrahydrofolate reductase (MTHFR), an enzyme involved in the metabolism of homocysteine, can lead to hyperhomocysteinemia that has already been related to cardiac outcomes and resistance to insulin. The A1298C and C677T polymorphisms in the MTHFR can reduce enzyme activity.

OBJECTIVE

The study aims to analyze the association between MTHFR genotypes and cardiac parameters in patients with DR.

METHODS

DM patients diagnosed with DR (n=65) were categorized and compared according to MTHFR genotypes A1298C (AA and AC+CC groups) and C677T (CC and CT+TT) groups; biochemical, cardiological, anthropometric, genetic, lifestyle and vitamin B9 and B12 consumption variables. Fischer's exact test and Poisson regression were performed to assess the relationship between variables.

RESULTS

Comparing echocardiographic and electrocardiogram parameters within genotypic groups, we found a significant association between left atrial dilation and C677T polymorphism. Left atrium diameter was higher in the T allele carriers (CT+TT group), with a prevalence ratio of 0.912. This association was confirmed in the regression model, including confounding variables. The other cardiac structural and functional parameters studied were not significantly associated with the A1298C or C677T genotypes.

CONCLUSION

The MTHFR C677T genotype may contribute to atrial remodeling in RD patients. We found an association between the diameter of the left atrium and the T allele of the MTHFR C677T polymorphism in patients with DR.

Cardioprotection Generated by Aerobic Exercise Training is Not Related to the Proliferation of Cardiomyocytes and Angiotensin-(1-7) Levels in the Hearts of Rats with Supravalvar Aortic Stenosis

BACKGROUND/AIMS

The beneficial effect of aerobic exercise training (ET) on cardiac remodeling caused by supravalvar aortic stenosis (AS) has been demonstrated in experimental studies; however, the mechanisms responsible for improving cardiac function are not entirely understood. We evaluated whether ET-generated cardioprotection in pressure-overloaded rats is dependent on cardiomyocyte proliferation, increased angiotensin-(1-7) (Ang-1-7) levels, and its receptor in the myocardium.

METHODS

Eighteen weeks after ascending AS surgery, Wistar rats were randomly assigned to four groups: sedentary control (C-Sed), exercised control (C-Ex), sedentary aortic stenosis (AS-Sed) and exercised aortic stenosis (AS-Ex) groups. The moderate treadmill exercise protocol was performed for ten weeks. The functional capacity was assessed by treadmill exercise testing. Cardiac structure and function were evaluated by echocardiogram. Cardiomyocyte proliferation was evaluated by flow cytometry. Expression of cell cycle regulatory genes as CCND2, AURKB, CDK1, and MEIS1 was verified by RT-qPCR. Cardiac and plasma angiotensin I (Ang I), angiotensin II (Ang II), and Ang-(1-7) levels were analyzed by high-performance liquid chromatography (HPLC). The angiotensin-converting enzyme (ACE) activity was assessed by the fluorometric method and protein expression of AT1 and Mas receptors by Western blot.

RESULTS

The AS-Ex group showed reduced left ventricular wall relative thickness and improved ejection fraction; also, it showed decreased gene expression of myocyte cell cycle regulators, ACE, Ang I, Ang II and Ang II/Ang-(1-7) ratio levels compared to AS-Sed group. However, ET did not induce alterations in Ang-(1-7) and cardiac Mas receptor expression and myocyte proliferation.

CONCLUSION

Aerobic exercise training improves systolic function regardless of myocyte proliferation and Ang-(1-7)/Mas receptor levels. However, the ET negatively modulates the vasoconstrictor/hypertrophic axis (ACE/Ang II) and decreases the expression of negative regulatory genes of the cell cycle in cardiomyocytes of rats with supravalvular aortic stenosis.

Proapoptotic Effects of triazol-1,4-Naphthoquinones Involve Intracellular ROS Production and MAPK/ERK Pathway in Human Leukemia Cells

BACKGROUND

The natural products constitute an important source of antitumor and cytotoxic agents. Naphthoquinones are effectively quinones present in different plants, with demonstrated anticancer activities. A recent study conducted by our group demonstrated the antileukemic potential of two novel triazol-1,4- naphthoquinones derivatives, PTN (2-(4-Phenyl-1H-1,2,3-triazol-1-yl)-1,4-naphthoquinone) and MPTN (2-[4- (4-Methoxyphenyl)-1H-1,2,3-triazol-1-yl]-1,4-naphthoquinone). Although, the mechanisms underlying the proapoptotic effects of PTN and MPTN have not been fully elucidated so far.

OBJECTIVE

The aim of this study was to evaluate the proapoptotic mechanism of PTN and MPTN in human acute leukemia cells.

METHODS

We used fluorescence microscopy to observe acridine orange and annexin V staining cells. Flow cytometry assay has also been used for ROS quantification, BAX and cytochrome c proteins expression and apoptosis analysis. MTT assay and western blotting technique have been performed as well for MAPK pathway analysis.

RESULTS

By using the acridine orange and annexin V staining with fluorescence microscopy, we have characterized the proapoptotic effects of PTN and MPTN in HL-60 cells involving the intrinsic mitochondrial pathway, since these compounds promoted an increase in the intracellular BAX and cytochrome c protein levels (p<0.05). We further demonstrated that apoptosis induction in HL-60 cells was mediated by increasing intracellular ROS levels via ERK but not p38 MAPKs pathway.

CONCLUSION

Taken together, these results have demonstrated that PTN and MPTN are promising tools for the development of new anti-leukemic drugs.

Cardiorespiratory alterations in rodents experimentally envenomed with Hadruroides lunatus scorpion venom

Background

Hadruroides lunatus is the most abundant scorpion species in the Peruvian central coast, where most of the accidents involving humans are registered. In spite of its prevalence, there are only very few studies on H. lunatus envenomation. The aim of the present study was to analyze the cardiorespiratory alterations caused by H. lunatus envenomation in rodents.

Methods

Wistar rats injected with H. lunatus scorpion venom were submitted to electrocardiography. After euthanasia, rat lungs were collected and histopathologically analyzed. Mouse cardiomyocytes were used to perform immunofluorescence and calcium transient assays. Data were analyzed by ANOVA or Student’s t-test. The significance level was set at p < 0.05.

Results

It was observed that H. lunatus venom increased heart rate and caused arrhythmia, thereby impairing the heart functioning. Lungs of envenomed animals showed significant alterations, such as diffuse hemorrhage. In addition, immunofluorescence showed that H. lunatus venom was capable of binding to cardiomyocytes. Furthermore, mouse ventricular cardiomyocytes incubated with H. lunatus venom showed a significant decrease in calcium transient, confirming that H. lunatus venom exerts a toxic effect on heart.

Conclusion

Our results showed that H. lunatus venom is capable of inducing cardiorespiratory alterations, a typical systemic effect of scorpionism, stressing the importance of medical monitoring in envenomation cases.

Non-neuronal cholinergic machinery present in cardiomyocytes offsets hypertrophic signals

Recent work has provided compelling evidence that increased levels of acetylcholine (ACh) can be protective in heart failure, whereas reduced levels of ACh secretion can cause heart malfunction. Previous data show that cardiomyocytes themselves can actively secrete ACh, raising the question of whether this cardiomyocyte derived ACh may contribute to the protective effects of ACh in the heart. To address the functionality of this non-neuronal ACh machinery, we used cholinesterase inhibitors and a siRNA targeted to AChE (acetylcholinesterase) as a way to increase the availability of ACh secreted by cardiac cells. By using nitric oxide (NO) formation as a biological sensor for released ACh, we showed that cholinesterase inhibition increased NO levels in freshly isolated ventricular myocytes and that this effect was prevented by atropine, a muscarinic receptor antagonist, and by inhibition of ACh synthesis or vesicular storage. Functionally, cholinesterase inhibition prevented the hypertrophic effect as well as molecular changes and calcium transient alterations induced by adrenergic overstimulation in cardiomyocytes. Moreover, inhibition of ACh storage or atropine blunted the anti-hypertrophic action of cholinesterase inhibition. Altogether, our results show that cardiomyocytes possess functional cholinergic machinery that offsets deleterious effects of hyperadrenergic stimulation. In addition, we show that adrenergic stimulation upregulates expression levels of cholinergic components. We propose that this cardiomyocyte cholinergic signaling could amplify the protective effects of the parasympathetic nervous system in the heart and may counteract or partially neutralize hypertrophic adrenergic effects.