Daily melatonin administration improves osseointegration in pinealectomized rats

Abstract The hypothesis of this study was that the peri-implant bone healing of the group of pinealectomized rats would differ from the control group. The samples were subjected to immunohistochemical, microtomographic (total porosity and connectivity density), and fluorochrome (mineralized surface) analyses. Objectives The goal of this study was to investigate the cellular changes and bone remodeling dynamics along the bone/implant interface in pinealectomized rats. Material and Methods The total of 18 adult male rats (Rattus norvegicus albinus, Wistar) was divided into three groups (n=6): control (CO), pinealectomized without melatonin (PNX) and pinealectomized with melatonin (PNXm). All animals were submitted to the first surgery (pinealectomy), except the CO group. Thirty days after the pinealectomy without melatonin, the second surgery was conducted, in which all animals received an implant in each tibia (36 titanium implants with surface treatment were installed - Implalife® São Paulo, SP, Brazil). By gavage, the rats of the PNX group received the vehicle solution, and the procedure. Results Immunohistochemical analysis for runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteopontin (OP) and osteocalcin (OC) showed that the bone repair process in the PNXm group was similar to that of the CO group, whereas the PNX group showed a delay. The microtomographic parameters of total porosity [Po(tot)] and bone surface (BS) showed no statistically significant differences, whereas for the connective density (Conn.Dn) a statistical difference was found between the CO and PNXm groups. Fluorochrome analysis of the active mineralized surface showed statistically significant difference between the CO and PNX and between the CO and PNXm groups. Conclusion The absence of the pineal gland impaired the bone repair process during osseointegration, however the daily melatonin replacement was able to restore this response.

Ritmo circadiano em óbitos hospitalares: comparação entre unidade de tratamento intensivo e unidade de tratamento não intensivo / Circadian rhythm of hospital deaths: comparison between intensive care unit and non-intensive care unit

OBJETIVO: A demonstração de que a mortalidade cardiovascular segue um ritmo circadiano fez com que fosse verificado se pacientes que falecem em unidade de tratamento intensivo (UTI) e unidade clínica (UC) obedecem a este ritmo. MÉTODOS: Foram analisados todos os óbitos hospitalares ocorridos entre 1º de janeiro de 2006 e 31 de julho de 2010. O padrão circadiano dos óbitos foi analisado dividindo-se as 24 horas do dia em períodos de 2 horas. Utilizou-se o teste do qui-quadrado para comparação de variáveis categóricas e o teste t de Student ou a análise da variância fator único para comparação de variáveis contínuas. Um valor de p < 0,05 foi considerado estatisticamente significante. RESULTADOS: No período estudado, foram registrados 700 óbitos, 211 (30,1 por cento) na UTI e 88 (12,6 por cento) na UC. Houve mais óbitos nas primeiras horas do dia, entre 6 e 12 h, na UC, em comparação à UTI (38 por cento vs. 21 por cento; p = 0,004). Na UTI, 21 por cento dos óbitos ocorreram entre 6 e 12 h, 30 por cento entre 12 e 18 h, 26 por cento entre 18 e 24 h e 24 por cento entre 24 e 6 h (p = 0,13). Enquanto, na UC, 38 por cento ocorreram entre 6 e 12 h, 18 por cento entre 12 e 18h, 19 por cento entre 18 e 24 h e 25 por cento entre 24 e 6 h (p = 0,005). CONCLUSÃO: Na UC, os óbitos ocorrem com maior frequência no período da manhã e seguem um padrão circadiano, enquanto na UTI esse fenômeno não ocorre.

OBJECTIVE: The demonstration that cardiovascular mortality follows a circadian rhythm led us to verify whether patients dying at the intensive unit care (ICU) and at the non-intensive unit care (non-ICU) follow that rhythm. METHODS: All hospital's deaths occurring between January 1, 2006 and July 31, 2010 were analyzed. The circadian pattern of the time of death was analyzed in twelve 2 hour intervals. The Chi-square test was used to compare proportions, and Student's t test or ANOVA single factor to compare continuous variables. A p-value < 0.05 was considered statistically significant. RESULTS: During the study period 700 deaths occurred in the hospital, 211 (30.1 percent) at the ICU and 88 (12.6 percent) at the non-ICU. There were more deaths in the first hours of the day, between 6 am and 12 am, at the non-ICU in comparison to the ICU (38 percent vs. 21 percent; p = 0.004). In the ICU, we observed that 21 percent of the deaths occurred between 6 am and 12 pm, 30 percent between 12 pm and 6 pm, 26 percent between 6 pm and 12 am and 24 percent between 12 am and 6 am (p = 0.13), whereas, at the non-ICU, 38 percent of the deaths occurred between 6 am and 12 pm, 18 percent between 12 pm and 6 pm, 19 percent between 6 pm and 12 am and 25 percent between 12 am and 6 am (p = 0.005). CONCLUSION: At the non-ICU, deaths occur more often in the morning period and follow a circadian rhythm, which does not occur at the ICU.