Effects of concurrent training and N-acetylcysteine supplementation on cardiac remodeling and oxidative stress in middle-aged spontaneously hypertensive rats.

BACKGROUND: This study evaluated the effects of concurrent isolated training (T) or training combined with the antioxidant N-acetylcysteine (NAC) on cardiac remodeling and oxidative stress in spontaneously hypertensive rats (SHR). METHODS: Six-month-old male SHR were divided into sedentary (S, n = 12), concurrent training (T, n = 13), sedentary supplemented with NAC (SNAC, n = 13), and concurrent training with NAC supplementation (TNAC, n = 14) groups. T and TNAC rats were trained three times a week on a treadmill and ladder; NAC supplemented groups received 120 mg/kg/day NAC in rat chow for eight weeks. Myocardial antioxidant enzyme activity and lipid hydroperoxide concentration were assessed by spectrophotometry. Gene expression of NADPH oxidase subunits Nox2, Nox4, p22 phox, and p47 phox was evaluated by real time RT-PCR. Statistical analysis was performed using ANOVA and Bonferroni or Kruskal-Wallis and Dunn. RESULTS: Echocardiogram showed concentric remodeling in TNAC, characterized by increased relative wall thickness (S 0.40 ± 0.04; T 0.39 ± 0.03; SNAC 0.40 ± 0.04; TNAC 0.43 ± 0.04 *; * p < 0.05 vs T and SNAC) and diastolic posterior wall thickness (S 1.50 ± 0.12; T 1.52 ± 0.10; SNAC 1.56 ± 0.12; TNAC 1.62 ± 0.14 * mm; * p < 0.05 vs T), with improved contractile function (posterior wall shortening velocity: S 39.4 ± 5.01; T 36.4 ± 2.96; SNAC 39.7 ± 3.44; TNAC 41.6 ± 3.57 * mm/s; * p < 0.05 vs T). Myocardial lipid hydroperoxide concentration was lower in NAC treated groups (S 210 ± 48; T 182 ± 43; SNAC 159 ± 33 *; TNAC 110 ± 23 *# nmol/g tissue; * p < 0.05 vs S, # p < 0.05 vs T and SNAC). Nox 2 and p22 phox expression was higher and p47 phox lower in T than S [S 1.37 (0.66-1.66); T 0.78 (0.61-1.04) *; SNAC 1.07 (1.01-1.38); TNAC 1.06 (1.01-1.15) arbitrary units; * p < 0.05 vs S]. NADPH oxidase subunits did not differ between TNAC, SNAC, and S groups. CONCLUSION: N-acetylcysteine supplementation alone reduces oxidative stress in untreated spontaneously hypertensive rats. The combination of N-acetylcysteine and concurrent exercise further decreases oxidative stress. However, the lower oxidative stress does not translate into improved cardiac remodeling and function in untreated spontaneously hypertensive rats.

Involvement of phospholipase A2 in the neuromuscular blockade caused by coralsnake (Micrurus spp.) venoms in mouse phrenic nerve-diaphragm preparations in vitro.

In this work, we examined the neuromuscular blockade caused by venoms from four South-American coralsnakes (Micrurus altirostris - MA, M. corallinus - MC, M. spixii - MS, and M. dumerilii carinicauda - MDC) and the ability of varespladib (VPL), a phospholipase A2 (PLA2) inhibitor, to attenuate this blockade. PLA2 activity was determined using a colorimetric assay and a fixed amount of venom (10 µg). Neurotoxicity was assayed using a single concentration of venom (10 µg/ml) in mouse phrenic nerve-diaphragm (PND) preparations mounted for myographic recordings and then subjected to histological analysis. All venoms showed PLA2 activity, with MS and MA venoms having the highest (15.53 ± 1.9 A425 nm/min) and lowest (0.23 ± 0.14 A425 nm/min) activities, respectively. VPL (292 and 438 µM) inhibited the PLA2 activity of all venoms, although that of MA venom was least affected. All venoms caused neuromuscular blockade, with MS and MDC venoms causing the fastest and slowest 100% blockade [in 40 ± 3 min and 120 ± 6 min (n = 4), respectively]; MA and MC produced complete blockade within 90-100 min. Preincubation of venoms with 292 µM VPL attenuated the blockade to varying degrees: the greatest inhibition was seen with MDC venom and blockade by MS venom was unaffected by this inhibitor. These results indicate that PLA2 has a variable contribution to coralsnake venom-induced neuromuscular blockade in vitro, with the insensitivity of MS venom to VPL suggesting that blockade by this venom is mediated predominantly by post-synaptically-active α-neurotoxins.

Cardiac Effects of Micrurus corallinus and Micrurus dumerilii carinicauda (Elapidae) Venoms and Neutralization by Brazilian Coralsnake Antivenom and Varespladib.

In this work, we examined the action of two South American coralsnake (Micrurus corallinus and Micrurus dumerilii carinicauda) venoms on rat heart function in the absence and presence of treatment with Brazilian coralsnake antivenom (CAV) and varespladib (VPL), a potent phospholipase A2 inhibitor. Anesthetized male Wistar rats were injected with saline (control) or a single dose of venom (1.5 mg/kg, i.m.) and monitored for alterations in echocardiographic parameters, serum CK-MB levels and cardiac histomorphology, the latter using a combination of fractal dimension and histopathological methods. Neither of the venoms caused cardiac functional alterations 2 h after venom injection; however, M. corallinus venom caused tachycardia 2 h after venom injection, with CAV (given i.p. at an antivenom:venom ratio of 1:1.5, v/w), VPL (0.5 mg/kg, i.p.) and CAV + VPL preventing this increase. Both venoms increased the cardiac lesional score and serum CK-MB levels compared to saline-treated rats, but only the combination of CAV + VPL prevented these alterations, although VPL alone was able to attenuate the increase in CK-MB caused by M. corallinus venom. Micrurus corallinus venom increased the heart fractal dimension measurement, but none of the treatments prevented this alteration. In conclusion, M. corallinus and M. d. carinicauda venoms caused no major cardiac functional alterations at the dose tested, although M. corallinus venom caused transient tachycardia. Both venoms caused some cardiac morphological damage, as indicated by histomorphological analyses and the increase in circulating CK-MB levels. These alterations were consistently attenuated by a combination of CAV and VPL.

Consumption, nicotine dependence and motivation for smoke cessation during early stages of COVID-19 pandemic in Brazil: A cross-sectional study.

INTRODUCTION: The COVID-19 pandemic may have changed smoking habits. For the smoking population, information regarding smoking habits and the pandemic could potentially aid COVID-19 prevention and control measures. Our study aimed to analyze the effects of the COVID-19 pandemic on tobacco consumption, nicotine dependence levels, and motivation for smoking cessation. We also collected information from smokers regarding their awareness of the consequences of tobacco use and the increased risks smokers have for severe complications from COVID-19. METHODS: In the survey for this observational cross-sectional study, 122 smokers responded to an online form. The participants provided general data about their smoking history, their smoking habits in the months of April and May 2020, and the effect of the pandemic on their smoking habits. They also completed a Fagerström test and were measured by the Wisconsin Smoking Withdrawal Scale. RESULTS: When compared to pre-pandemic levels, the majority of smokers reported increased tobacco consumption of between 1 and 10 cigarettes per day (37.7%). Their motivation to quit smoking (59.8%) and desire to smoke (53.2%) were unchanged by the pandemic. Most participants demonstrated an awareness of the increased risks smokers have for severe COVID-19-related complications (p<0.001). We identified the following correlations: cigarettes/day before pandemic and motivation for smoking cessation (r=0.19; p=0.030), cigarettes/day and nicotine dependence level (r=0.61; p<0.001), and load consumption and nicotine dependence level (r=0.69; p<0.001). No significant correlations were observed between load consumption and motivation to quit (r=0.13; p=0.120). CONCLUSIONS: Most smokers are well aware of their increased risks for severe COVID-19-related complications. In the early stages of the COVID-19 pandemic in Brazil, most smokers reported increased cigarette consumption. In addition, motivation to quit and desire to smoke were unchanged for the majority of smokers.

Effects of training volume on lower-body muscle strength in untrained young men: a contralateral control study

The purpose of this study was to examine the effects of training volume (1 vs. 3 sets) on lower-body muscle strength in untrained young men. Methodsː Eighteen untrained young men were recruited and their legs were trained with 1 or 3 sets (in a contralateral design) for 6 weeks, using a knee extension machine. Isokinetic peak torque and one repetition maximum (1RM) were assessed at pre- and post-training. Resultsː There was a similar improvement in the 1RM strength (1SET: +14.8% vs. 3SET: 16.3%, P > 0.05) and peak torque (1SET: +8.1% vs. 3SET: 9.3%, P > 0.05) for both conditions from pre- to post-training. The effect size (ES) for the change in 1RM was moderate for both conditions (1SET: 1.39 vs. 3SET: 1.41), and peak torque was trivial and small for 1SET (0.47) and 3SET (0.55), respectively. Additionally, there were no significant (P > 0.05) differences in the dietary intakes from pre- to post-training. Conclusionsː Our results indicate that 1 set is as effective as 3 sets for increasing lower-body muscle strength after a short-term RT period (6 weeks) in untrained young men.(AU)

Dynamics of heart rate variability analysed through nonlinear and linear dynamics is already impaired in young type 1 diabetic subjects.

BACKGROUND: Autonomic diabetic neuropathy is one of the most common complications of type 1 diabetes mellitus, and studies using heart rate variability to investigate these individuals have shown inconclusive results regarding autonomic nervous system activation. Aims To investigate the dynamics of heart rate in young subjects with type 1 diabetes mellitus through nonlinear and linear methods of heart rate variability. METHODS: We evaluated 20 subjects with type 1 diabetes mellitus and 23 healthy control subjects. We obtained the following nonlinear indices from the recurrence plot: recurrence rate (REC), determinism (DET), and Shanon entropy (ES), and we analysed indices in the frequency (LF and HF in ms2 and normalised units - nu - and LF/HF ratio) and time domains (SDNN and RMSSD), through analysis of 1000 R-R intervals, captured by a heart rate monitor. RESULTS: There were reduced values (p<0.05) for individuals with type 1 diabetes mellitus compared with healthy subjects in the following indices: DET, REC, ES, RMSSD, SDNN, LF (ms2), and HF (ms2). In relation to the recurrence plot, subjects with type 1 diabetes mellitus demonstrated lower recurrence and greater variation in their plot, inter-group and intra-group, respectively. CONCLUSION: Young subjects with type 1 diabetes mellitus have autonomic nervous system behaviour that tends to randomness compared with healthy young subjects. Moreover, this behaviour is related to reduced sympathetic and parasympathetic activity of the autonomic nervous system.

Comparação dos efeitos da ventilação mecânica não invasiva contínua e intermitente sobre parâmetros cardiorrespiratórios e modulação autonômica de indivíduos saudáveis / Comparison of the effects of continuous and intermittent non invasive mechanical ventilation on cardiorespiratory parameters and autonomic modulation of healthy individuals

Modelo do estudo: Estudo transversal. Objetivo: Avaliar a influência da Ventilação Mecânica não Invasiva (VMNI) de forma contínua e intermitente sobre a modulação autonômica cardíaca e parâmetros cardiorrespiratórios em mulheres saudáveis. Métodos: Vinte voluntárias realizaram duas modalidades de VMNI: contínua por meio do CPAP e intermitente por meio do Reanimador de Muller. Inicialmente permaneceram em repouso em respiração espontânea por 20 minutos. Em seguida foram submetidas a 20 minutos de aplicação de VMNI com a técnica selecionada e por fim permaneceram 20 minutos em repouso em respiração espontânea. Os parâmetros cardiorrespiratórios e variabilidade da frequência cardíaca (VFC) foram mensurados em todos estes momentos. Resultados: Não houve diferenças significantes quando comparadas as duas técnicas. Observaram-se diferenças nos parâmetros cardiorrespiratórios e VFC quando analisadas individualmente. Menores valores de frequência cardíaca e frequência respiratória foram observados na modalidade contínua quando comparado os valores durante a ventilação com respiração espontânea (p<0,005). Em ambas técnicas observaram-se aumentos significantes de SpO2 durante a ventilação em comparação a respiração espontânea. Observou-se aumento da modulação parassimpática (RMSSD, HF ms2 e SD1) e da variabilidade global (SDNN, RR triangular e SD2) em ambas as técnicas quando comparado ventilação e respiração espontânea (p<0,005). Conclusão: Não houve diferença quando comparadas as duas modalidades de VMNI. Contudo, quando analisadas individualmente observam-se comportamento diferentes dos parâmetros cardiorrespiratórios e na modulação autonômica.

Study design: Cross-sectional study. Objective: To evaluate the influence of continuous and intermittent non invasive mechanical ventilation (NIV) on cardiac autonomic modulation and cardiorespiratory parameters in healthy women. Methods: Twenty subjects performed two types of NIV: continuous through CPAP and intermittent through Müller Reanimator. Initially they remained at rest for 20 minutes in spontaneous breathing. Then volunteers were subjected to 20 minutes of NIV application with the selected technique and finally remained at rest for 20 minutes in spontaneous breathing. Cardiorespiratory parameters and heart rate variability (HRV) were measured in all these moments. Results: Therewere no significant differences when comparing the two techniques. Differences were observed in HRVand cardiorespiratory parameters when analyzed individually. Lower values of heart rate and respiratory rate were observed in continuous ventilation when compared to values during ventilation with spontaneous breathing (p <0.005). In both techniques we observed significant increases in SpO2 during ventilation compared to spontaneous breathing. We observed an increase in parasympathetic modulation (RMSSD, HF ms2 and SD1) and overall variability (SDNN, RR triangular and SD2) in both techniques when compared ventilation to spontaneous breathing (p <0.005). Conclusion: There was no difference comparing the two types of NIV. However, when analyzed individually we observe different behavior of cardiorespiratory parameters and autonomic modulation.

Influence of Time and Frequency of Passive Smoking Exposure on Mucociliary Clearance and the Autonomic Nervous System.

BACKGROUND: There are still gaps in the knowledge regarding the damage to mucociliary and autonomous systems from passive exposure to cigarette smoke. Also, the influence of the frequency and duration of exposure on these systems is still unclear. The objective of this work was to verify the effects of passive smoking on mucociliary clearance and adult autonomic nervous systems and investigate the influence of frequency and time of passive exposure on these systems. METHODS: 44 smokers (smoking group), 38 passive smokers (passive smoking group), and 38 healthy individuals (control group) were evaluated. Evaluation of lung function was performed. To analyze the autonomic nervous system, heart rate variability data were collected. Hemodynamic parameters were collected. Mucociliary clearance was evaluated using the saccharin transit time test. RESULTS: The passive smoking group presented reduced lung function (P = .02). Systolic blood pressure was significantly greater in the passive smoking group when compared with the smoking group (P = .02). The passive smoking group presented significantly slower transportability time than the control group. No differences were observed between the groups for the heart rate variability data. There was a significant correlation (P < .05) between the frequency of exposure and diastolic blood pressure, oxygen saturation, and FEF(25-75%). Correlation analyses also demonstrated a reduction of global autonomic activity according to exposure load, in addition to a reduction in vagal activity and an increase in sympathetic activity according to exposure frequency. CONCLUSIONS: Passive smokers presented worse mucociliary clearance, and there was a correlation between passive exposure load and damage to the hemodynamic response, pulmonary function and autonomic nervous system.