The influence of LLLT applied on applied on calvarial defect in rats under effect of cigarette smoke

Abstract Objective Considering the global public health problem of smoking, which can negatively influence bone tissue repair, the aim of this study is to analyze the influence of photobiomodulation therapy (PBM) on calvaria defects created surgically in specimens under the effect of cigarette smoke and analyzed with use of histomorphometric and immunohistochemistry techniques. Methodology Calvaria defects 4.1 mm in diameter were surgically created in the calvaria of 90-day-old rats (n=60) that were randomly divided into 4 experimental groups containing 15 animals each: control group (C), smoking group (S), laser group (L), and smoke associated with laser group (S+L). The animals were subjected to surgery for calvaria defects and underwent PBM, being evaluated at 21, 45, and 60 days post-surgery. The specimens were then processed for histomorphometric and immunohistochemistry analyses. The area of bone neoformation (ABN), percentage of bone neoformation (PBNF), and the remaining distance between the edges of the defects (D) were analyzed histometrically. Quantitative analysis of the TRAP immunolabeled cells was also performed. The data were subjected to analysis of variance (ANOVA) in conjunction with Tukey's test to verify the statistical differences between groups (p<0.05). Results The smoking group showed less ABN compared to the other experimental groups in all periods, and it also showed more D at 21 days compared to the remaining groups and at 45 days compared to the laser group. The smoking group showed a lower PNBF compared to the laser group in all experimental periods and compared to smoking combined with LLLT group at 21 days. Conclusions PBM acted on bone biomodulation, thus stimulating new bone formation and compensating for the negative factor of smoking, which can be used as a supportive therapy during bone repair processes.

The effects of cigarette smoking on ventricular repolarization in adolescents / O tabagismo altera a repolarização ventricular em adolescentes

ABSTRACT Objective To assess the association between cigarette smoking and ventricular arrhythmias in adolescents. Novel electrocardiographic parameters -Tp-e interval, as well as Tpe/QT and Tpe/QTc ratios - were used to make this assessment. Methods The study population consisted of 87 subjects aged between 16-19 years. Fifty-one adolescent smokers with no risk of arrhythmia comprised the Smoker Group, and 36 adolescents who had never smoked cigarettes comprised the Control Group. Smokers were defined as patients smoking more than three cigarettes per day, for at least 1 year. Body mass index, systolic, diastolic and mean blood pressures were measured, and electrocardiograms were performed on all subjects. Heart rate, PR and Tp-e intervals, and Tpe/QT, Tpe/QTc ratio were digitally measured. Results Adolescents in Smoker Group had smoked cigarettes for 2.9±1.4 years (range 1 to 6 years). The mean age at starting smoking was 13.8±1.4 years. There were no differences between smokers and Control Group as to baseline clinical variables (p>0.05). The PR, QT and QTc intervals were similar in all groups. Tp-e interval (98.4±12.7ms and 78.3±6.9 ms; p<0.001), Tpe/QT (0.28±0.04 and 22±0.03; p<0.01), Tpe/QTc (0.24±0.03 and 0.19±0.01; p<0.001) ratios were significantly higher in Smoker Group. There were no correlations between years of smoking, number of cigarettes per day, Tpe interval, Tpe/QT or Tpe/QTc ratios. Conclusion Cigarette smoking is associated with risk of ventricular arrhytmogenesis with prolonged Tp-e interval and increased Tpe/QT and Tpe/QTc ratios in adolescents.

RESUMO Objetivo Avaliar a associação entre tabagismo e arritmias ventriculares em adolescentes usando novos parâmetros eletrocardiográficos: intervalo Tp-e, e relações Tpe/QT e Tpe/QTc. Métodos A população do estudo incluiu 87 indivíduos de 16 a 19 anos de idade. Cinquenta e um adolescentes fumantes, sem risco de arritmia, formaram o Grupo Fumantes, e 36 adolescentes, que nunca tinham fumado cigarros, formaram o Grupo Controle. Os fumantes foram definidos como pacientes que fumavam mais de três cigarros por dia, há pelo menos 1 ano. O índice de massa corporal, e a pressão arterial sistólica, diastólica e média foram medidos, e foram realizados eletrocardiogramas em todos os participantes. Frequência cardíaca, intervalos PR e Tp-e, e as relações Tpe/QT e Tpe/QTc foram medidas por instrumentos digitais. Resultados Os adolescentes do Grupo Fumante fumavam há 2,9±1,4 anos (variação 1 a 6 anos). A média de idade ao começar a fumar foi 13,8±1,4 anos. Não houve diferença nas variáveis clínicas iniciais entre os Grupos Fumante e controle (p>0,05). Os intervalos PR, QT e QTc foram semelhantes em todos os grupos. O intervalo Tp-e (98,4±12,7ms e 78,3±6,9ms; p<0,001), e as relações Tpe/QT (0,28±0,04 e 22±0,03; p<0,01) e Tpe/QTc (0,24±0,03 e 0,19±0,01; p<0,001) foram significativamente maiores no Grupo Fumantes. Não houve correlação entre anos de tabagismo, número de cigarros por dia, intervalo Tpe e relações Tpe/QT e Tpe/QTc. Conclusão O hábito de fumar está associado ao risco de arritmogênese ventricular, com interval Tp-e prolongado e aumento nas relações Tpe/QT e Tpe/QTc em adolescentes.