Análisis microbiológico a corto y largo plazo del material usado para esterilizar instrumental odontológico / Short and long-term microbiological analysis of the material for sterilize dental instruments

Introducción: el material para empaquetar el instrumental odontológico, como pueden ser bolsas de tela, papel o plástico, es usado por profesionales de la salud; sin embargo, es necesario esclarecer la efectividad de cada uno y determinar el tiempo que permanece estéril luego del procedimiento. Objetivo: identificar la eficacia de tela, plástico y papel como materiales para esterilizar instrumental a corto y largo plazo. Material y métodos: se realizaron cultivos sólidos y líquidos de instrumental esterilizado en tres materiales y con diferentes tiempos de postesterilización. Se incubaron a 36 oC por 72 horas en condiciones aerobias y anaerobias. Los resultados se analizaron usando una prueba de Kruskal-Wallis, seguida de una prueba de Dunn. Resultados: los resultados mostraron que inmediatamente después del proceso de esterilización, los tres materiales son efectivos (Kruskal-Wallis test, p = 0.2752), 24 horas (p = 0.2492), siete (p = 0.0509) y 14 días (p = 0.0006). Veinticuatro horas posterior a la esterilización la tela no es efectiva, el plástico disminuye su efectividad y el papel sigue siendo efectivo. Conclusión: en nuestros resultados, el papel es la mejor opción para esterilizar instrumental (AU)

Introduction: material such as cloth, paper or plastic bags to wrap dental instruments is used by health professionals, however, it is necessary to clarify the effectiveness of each one and determine if it remains sterile after the procedure. Objective: to determine the effectiveness of cloth, plastic and paper as materials to sterilize dental instruments in the short and long term. Material and methods: we carry out solid and liquid cultures of sterilized instruments in three materials, at different post-sterilization times, incubated at 36 oC for 72 hours under aerobic and anaerobic conditions, and the results were analyzed using a Kruskal-Wallis test, followed by from a Dunn's test. Results: our results showed that immediately after the sterilization process the three materials are effective (Kruskal-Wallis; p = 0.2752), 24 hours (p = 0.2492), 7 (p = 0.0509) and 14 (p = 0.0006) days. Twenty-four hours after the cloth is not effective, plastic decreases its effectiveness and paper remain effective. Conclusion: in our results, paper is the best option to sterilize dental instruments (AU)

Differential metabolism of brown adipose tissue in newborn rabbits in relation to position in the litter huddle.

Competition for resources can contribute importantly to the early development of individual differences in behavioral and physiological phenotypes. In newborn rabbits, littermates compete for thermally favorable positions within the litter huddle. As brown adipose tissue (BAT) is the principal site of thermogenesis in such altricial young, we investigated differences in rabbit pups' growth and morphological differences in BAT associated with position within the huddle. We formed three treatment groups (7 litters/group): GI-birth (pups killed at birth); GII-chronic thermal challenge (pups killed after exposure to a moderately cold environmental during postnatal days 1-3); GIII-acute thermal challenge (as for GII but pups killed after an additional 30min exposure to a very cold environment on postnatal day 3). Interscapular BAT was removed at death for histological analysis, and triglyceride concentrations measured in serum. Pups occupying central positions in the huddle had higher skin temperatures, obtained more milk, and were more efficient at converting this into body mass, than pups occupying peripheral positions. There was no significant difference in BAT morphology or triglyceride concentrations between pups at birth, nor between central and peripheral pups chronically exposed to moderate cold until postnatal day 3. However, during acute cold exposure at this age, peripheral pups were less able to maintain their body temperature, they depleted BAT fat reserves almost completely, and they had lower serum concentrations of triglycerides than central pups. These findings confirm the contribution of early sibling relations to individual differences in growth and metabolic processes associated with thermoregulation in newborn rabbits.

Development of behavior in the litter huddle in rat pups: within- and between-litter differences.

Early postnatal growth in mammals can be considerably influenced by litter size and often differs among littermates in relation to birth mass. In a study of Long Evans laboratory rats we asked whether within- and between-litter differences in body mass and growth are related to behavioral development during early postnatal life. For this, we analyzed the amount of general motor activity and the display of directed, seemingly goal-oriented interactions within the litter huddle in previsual pups. During the study period from postnatal days 2 to 11, we found significant changes in pup behavior, showing a nonlinear, quadratic shape. General motor activity and, more specifically, the display of behaviors apparently directed to reaching central positions in the litter huddle increased during the first postnatal days and then decreased again. However, pups from small litters that grow more rapidly than pups from large litters, showed a faster increase in both behaviors, whereas the young from large litters reached a higher maximum. We also found striking within-litter differences in the amount of directed behavior performed by light and heavy pups, with higher levels in the former group, most probably because light pups that have a less favorable body mass-to-volume ratio and more often occupy peripheral positions in the litter huddle, make a greater effort to reach thermally favorable central positions. In conclusion, our study shows there to be consistent between-litter as well as within-litter differences in behavioral patterns during early life. These differences might have important implications for an individual's long-term behavioral and physiological performance.

Why do heavy littermates grow better than lighter ones? A study in wild and domestic European rabbits.

Birth mass can vary considerably among mammalian littermates. Heavier pups often show higher growth rates than their lighter siblings, which might positively affect fitness-relevant parameters during later life. Such a correlation between birth mass and pre-weaning growth within litters was confirmed by our study of wild-type and domestic European rabbits (Oryctolagus cuniculus) living in a semi-natural environment and under laboratory housing conditions, respectively. Our study indicates that at least two main mechanisms account for this relationship in our study species: heavier pups had a higher milk intake and also showed a more efficient conversion of milk into body mass. Furthermore, our study suggests that the better milk conversion by heavy pups was driven by three synergistic mechanisms: heavier pups had comparatively more huddling partners in the nest, they did not need to perform large amounts of proactive behavior in order to reach and remain in a central position within the litter huddle, and they could maintain a comparatively higher body temperature most probably due to their more favorable surface area to volume ratio. In conclusion, our study of European rabbits provides strong evidence that both under natural conditions and in the laboratory, within-litter differences in birth mass are maintained and may even increase during pups' early postnatal development.