Long-term effects of sprint interval training on expression of cardiac genes involved in energy efficiency

Purpose

The real mechanisms of intensive exercise training-induced energy efficiency have not yet been well examined. Therefore, the aim of the present study was to investigate the effects of sprint interval training (SIT) on gene expression of uncoupling proteins (UCPs) and endothelial nitric oxide synthase (eNOS).

Methods

For this purpose, 16 Albino Wistar rats (250–300 g) were randomly divided into equal groups of control and sprint training. The animals run on treadmill for 10 weeks, 5 days per week at intensity corresponding to 90–95% maximal oxygen consumption. The gene expression of UCP2, UCP3 and eNOS was analyzed by RT-PCR method in hearts. The data were analyzed by independent samples T test at P?<?0.05 level.

Results

Sprint interval training significantly decreased mRNA expression of UCP2 (t₁₄?=?4.818, P?=?0.001) and UCP3 (t₁₄?=?4.620, P?=?0.001) in cardiac muscle of rats. In contrast, mRNA expression of eNOS in cardiac muscle significantly increased following sprint interval training (t₁₄?=?7.967, P?=?0.001).

Conclusion

This study elucidates that SIT through reduction in gene expression of uncoupling proteins can improve energy efficiency. But, more studies are needed to confirm this hypothesis.

     

Increase in the effectiveness of somatodendritic 5-HT-1A receptors in a rat model of tardive dyskinesia

The present study concerns responsiveness of pre- and postsynaptic 5-hydroxytryptamine (5-HT)-1A receptors in a rat model of tardive dyskinesia (TD). Vacuous chewing movements (VCMs) in rats are widely accepted as an animal model of TD. Results show that haloperidol injected at a dose of 1 mg/kg twice a day for 5 weeks elicited VCMs, which increased in a time dependent manner following the drug administration for 3-5 weeks. Tolerance was produced in motor coordination during the potentiation of VCMs. Exploratory activity in an open field and in an activity box decreased in haloperidol treated animals. The effects of 8-hydroxy-2-(di-n-propylamino)tetraline (8-OH-DPAT; 0.5 mg/kg) were monitored 48-h after withdrawal from repeated administration of haloperidol. 8-OH-DPAT-induced locomotion was greater in haloperidol treated rats. 5-HT synthesis increased in haloperidol treated animals, while 8-OH-DPAT-induced decreases of 5-HT synthesis were greater in repeated haloperidol than repeated saline injected animals. The results suggest that an increase in the effectiveness of somatodendritic 5-HT-1A receptors may decrease the inhibitory influence of 5-HT on the activity of dopaminergic neurons to precipitate VCMs. The 5-HT-1A agonist may help to alleviate neuroleptic-induced TD.     

Prognostic value of positive T wave in lead aVR in patients with non‐ST segment myocardial infarction

Background

Lead aVR provides prognostic information in various settings in patients with ischemia. We aim to investigate the role of a positive T wave in lead aVR in non‐ST segment myocardial infarction (NSTEMI).

Methods

In a prospective cohort study, we included 400 patients with NSTEMI. Presentation electrocardiogram (ECG) was investigated for presence of a positive T wave as well as ST segment elevation (STE) in aVR and study variables were compared. Predictors of primary outcome defined as hospital major adverse cardiovascular events (MACE) and secondary outcome, defined as three‐vessel coronary disease and/or left main coronary artery stenosis (3VD/LMCA) stenosis in angiography, were determined in multivariate logistic regression analysis.

Results

Patients with a positive T wave in aVR were significantly older and were more likely to be female. Left ventricular ejection fraction was significantly lower in patients of positive T group. Positive T group was more likely to have 3VD/LMCA stenosis (58.3% vs. 19.8%, p < .001). The prevalence of a positive T wave in aVR was significantly higher in MACE group (54.9 % vs. 24.8%, p < .001). However, in multivariate analysis, it was not an independent predictor of MACE (OR: 1.083 95% CI: [0.496–2.365], p: .841). Though, it was independently associated with presence of 3VD/LMCA stenosis (OR: 3.747 95% CI: [2.058–6.822], p < .001).

Conclusion

Though positive T wave in lead aVR was more common in patients with MACE; it was not an independent predictor. Additionally, a positive T wave in aVR was an independent predictor of 3VD/LMCA stenosis in NSTEMI.

     

Tribological Behavior of Aluminum Hybrid Nanocomposites Reinforced with Alumina and Graphene Oxide

Due to rapid technological advancements, the demand for lightweight materials with improved tribo-mechanical properties is continuously growing. The development of composite materials is one of the routes taken by researchers to meet these target properties. Aluminum (Al) is one of the most suitable materials used for developing composites for a wide range of applications because of its light weight, high conductivity, and high specific strength. In this study, aluminum hybrid nanocomposites with alumina (10 Vol% Al₂O₃) and varying loadings of graphene oxide (0.25, 0.5 and 1 wt% GO) were fabricated using the spark plasma sintering technique. The tribological properties of the developed hybrid composites were evaluated by conducting ball-on-disk wear tests at a normal load of 3N, with a sliding speed of 0.1 m/s, and for a sliding distance of 100 m. A 440C hardened stainless steel ball with a diameter of 6.3 mm and a hardness of 62 RC was used as a counterface. Scanning electron microscopy (SEM), elemental X-ray dispersive analysis (EDS), and optical profilometry were used to ascertain the involved wear mechanisms. The results revealed that Al-10 Vol%Vol% Al₂O₃-0.25 wt% GO hybrid nanocomposite showed an increase of 48% in the hardness, a reduction of 55% in the specific wear rate, and a reduction of 5% in COF compared with pure aluminum.