Parent Attendance in a Family-Based Preventive Intervention Delivered in Latin America and the United States.

In Latin America, there is an increasing interest in the implementation and dissemination of evidence-based, family-centered interventions to prevent youth behavioral problems. While families' participation in interventions is integral to achieving the interventions' desired impact, little is known about what predicts Latin American families' attendance. The current study provides a unique opportunity to explore the participation of families living in the United States, Ecuador, and Chile in an evidence-based intervention, Familias Unidas. We tested for differences in attendance rates, family functioning variables, and adolescent behavioral problem variables, then applied a hierarchical multiple regression to (a) identify which variables significantly predicted program attendance and (b) assess whether the country in which the intervention was implemented in moderated the relationship between predictors and program attendance. On average, Chilean and Ecuadorian parents were more engaged and attended more sessions than parents living in the United States. Across samples, there was significant differences in family functioning and adolescent behavioral problem variables. However, effective parent-adolescent communication was the only significant predictor of lower program attendance. A significant interaction effect revealed that even though Chilean parents had high parent-adolescent communication, they were more likely to attend sessions, compared to parents living in the United States. We highlight the promise of engaging and retaining families, across U.S. and Latin American samples, into a culturally syntonic, family-based intervention, and discuss potential explanations for success in Chile and Ecuador. Researchers interested in implementing interventions in Latin America could utilize these findings to better target participants and intervention efforts.

Effect of land use and soil properties in the feasibility of two sequential extraction procedures for metals fractionation.

Several sequential extraction procedures are widely applied for metals chemical fractionation in the literature. However, their limitations to be used in different soils and metals have not been discussed in detail. This study compares two of the most commonly used extraction methods for metals chemical fractionation: Tessier and BCR. The objectives were to i) assess the differences between concentrations of metals extracted in each fraction by both Tessier and BCR procedures; ii) elucidate if soil properties affected the extraction ability of each fraction from both procedures; and iii) evaluate how land use contributes to different chemical metal distribution. Results indicated that both methods provide similar results when were applied to the same soil, since non-significant differences were found in metal concentrations between both methods at each fraction. Conversely, when we compared among land uses, significant differences were found in the metal concentration between both methods, especially between agricultural/urban/industrial against forest soil. Redundancy analysis showed that in carbonate-rich soils, BCR extraction method could cover up the real concentration of exchangeable metals with those bound to the carbonate phase, being the Tessier method the most suitable one for this kind of soils. Therefore, although sequential extraction is a useful tool to understand the distribution of metals in soil, the method used must be selected according to the land use and specific soil characteristics, taking into account at least, soil carbonate content.

Prevalence of Peri-implant Disease According to Periodontal Probing Depth and Bleeding on Probing: A Systematic Review and Meta-Analysis.

PURPOSE: To compare changes in the prevalence of peri-implantitis when the unit of analysis is the subject and when the unit of analysis is the implant, by means of meta-analysis with subgroup and sensitivity analyses, according to the case definition and cutoffs. Periodontal probing depth (PPD) and bleeding on probing (BOP) were considered the primary variables. MATERIALS AND METHODS: Electronic and manual searches of observational studies of implants with loading of more than 6 months were conducted. The quality of the studies was evaluated, and finally, a description (qualitative analysis) and a meta-analysis (quantitative analysis) of the available studies were performed. RESULTS: Fifty-five studies were included in this systematic review, 32 of which met the criteria for evaluation of disease based on PPD and BOP. A total of 2,734 subjects and 7,849 implants were evaluated. The prevalence of peri-implantitis, defined by PPD and BOP, was 17% when the unit of analysis was the subject, and 11% when it was the implant. If the clinical criterion was PPD ≥ 4 mm, the prevalence by subject was 34% and by implant 11%. If PPD was ≥ 5 mm, the prevalence by subject was 12% and by implant 10%. Finally, if the clinical criterion was PPD ≥ 6 mm, the prevalence by subject was 18% and by implant 10%. CONCLUSION: The prevalence of peri-implantitis is influenced by the criteria used for the case definition, and the true prevalence may currently be incorrectly estimated.

Terapia de resincronización cardíaca con o sin cardiodesfibrilador versus terapia con desfibrilador automático, Pereira (Colombia): un estudio de cohorte / Terapia de ressincronização cardíaca com ou sem cardiodesfibrilador versus terapia desfibrilador automático, Pereira (Colômbia): Um estudo de coorte / Cardiac resyncronization therapy with or without cardioverter-defibrillator versus defibrillator therapy alone, Pereira (Colombia): a cohort study

Comparar la supervivencia de pacientes con resincronizador cardíaco con o sin desfibrilador con la de pacientes con cardiodesfibrilador. Materiales y métodos: cohorte retrospectiva cuyo desenlace primario fue la mortalidad de origen cardíaco; la exposición fueron las terapias electrofisiológicas y la información se obtuvo de las historias clínicas y de otros registros médicos. Resultados: se estudiaron 70 pacientes de edad avanzada con dispositivos funcionales. El 82 % recibieron tratamiento farmacológico optimizado. No se encontró asociación significativa entre la probabilidad de supervivencia y la terapia de resincronización cardíaca con o sin cardiodesfibrilador versus la terapia con cardiodesfibrilador (log rank test p = 0,54), pero sí un mayor tiempo de supervivencia en los primeros (ANOVA p = 0,0012). La tasa de peligro fue 0,017 para el día 371 y del 0,15 para el día 2169. Durante el período de observación se presentaron 14 muertes, tres de ellas atribuibles a etiología no cardíaca. Conclusión: se observó que la terapia con resincronizador cardíaco se asoció de forma significativa con un mayor tiempo supervivencia...

To evaluate survival in patients with cardiac resynchronization with or without cardioverterdefibrillatorversus patients with implantable cardioverter-defibrillator alone. Materials and methods: Retrospective cohort, the primary end point was death from cardiac causes, the exposure was electrophysiological therapies, and the information sources were medical files and other records. Results: 70 elderly patients with functional devices; 82 % of them received optimized medical therapy. Nosignificant association was found between survival of patients with cardiac resynchronization therapy withor without defibrillator and cardioverter-defibrillator therapy alone (log rank test, p = 0.54), but the formerhad a longer survival time (ANOVA p = 0.0012). The hazard ratio was 0.017 for day 371 and 0.15 for day 169. Fourteen deaths occurred during the observation period, three of them from non-cardiac causes. Conclusion: Cardiac resynchronization therapy was associated with significantly longer survival time...

Comparar a sobrevivência de pacientes com ressincronizador cardíaco com ou sem desfibrilador em pacientes com desfibriladores. Materiais e métodos: corte retrospectivo de cujo principal resultado primário foi a mortalidade de origem cardíaca; a exposição foram as terapias e eletrofisiológicos e a informação foi obtida a partir da história clínica e outros registros médicos. Resultados: Foram estudados 70 pacientes idosos com dispositivos funcionais. 82 % receberam tratamento farmacológico otimizado. Não foi encontrado associação significativa entre a probabilidade de sobrevivencia e terapia de ressincronização cardíaca com ou sem cardiodesfibrilador versus a terapia cardiodesfibrilador (log rank test, p = 0,54 ), mas há um maior tempo de sobrevivência no primeiro (ANOVA, p = 0,0012 ). A taxa de risco foi 0,017 para o dia 371 e 0,15 para o dia 2169. Durante o período de observação, apresentaram 14 mortes, três deles atribuíveis a etiologia não cardíaca. Conclusão: constatou-se que a terapia com ressincronizador cardíaco foi significativamente asociado com um maior tempo de sobrevivência...

Simultaneous and successive inoculations of yeasts and lactic acid bacteria on the fermentation of an unsulfited Tannat grape must.

Interactions between yeasts and lactic acid bacteria are strain specific, and their outcome is expected to change in simultaneous alcoholic--malolactic fermentations from the pattern observed in successive fermentations. One Oenococcus oeni strain Lalvin VP41™ was inoculated with two Saccharomyces cerevisiae strains either simultaneously, three days after the yeast inoculation, or when alcoholic fermentation was close to finish. Early bacterial inoculations with each yeast strain allowed for the growth of the bacterial populations, and the length of malolactic fermentation was reduced to six days. Alcoholic fermentation by Lalvin ICV D80® yeast strain left the highest residual sugar, suggesting a negative effect of the bacterial growth and malolactic activity on its performance. In sequential inoculations the bacterial populations did not show actual growth with either yeast strain. In this strategy, both yeast strains finished the alcoholic fermentations, and malolactic fermentations took longer to finish. Lalvin ICV D80® allowed for higher viability and activity of the bacterial strain than Fermicru UY4® under the three inoculation strategies. This was beneficial for the sequential completion of both fermentations, but negatively affected the completion of alcoholic fermentation by Lalvin ICV D80® in the early bacteria additions. Conversely, Fermicru UY4®, which was rather inhibitory towards the bacteria, favored the timely completion of both fermentations simultaneously. As bacteria in early inoculations with low or no SO2 addition can be expected to multiply and interact with fermenting yeasts, not only are the yeast-bacterium strains combination and time point of the inoculation to be considered, but also the amount of bacteria inoculated.

Falla cardíaca avanzada en pacientestratados con dispositivos electrofisiológicos en una unidad de electrofisología, Pereira (Colombia) / Patients with advanced heart failure treated with electrophysiological devices in an electrophysiology center, Pereira(Colombia)

Resumen: la falla cardíaca avanzada es una enfermedad prevalente, con una tasaalta de mortalidad y hospitalización con relación a su estadio y perfil clínico, quecuesta en Norteamérica hasta el 20 por ciento de los recursos destinados para el manejo de la enfermedad cardiovascular. Se realizó un análisis transversal a una cohorte de 70 pacientes en tratamiento farmacológico y cardioresincronizador con o sin cardiodesfibirlador, o solo cardiodesfibrilador automático (ICD) implantado entre los años 2010 y 2012.Métodos: el presente es un estudio transversal. Resultados: 71 por ciento presentaron hipertensión arterial HTA; 65,75 por ciento cardiopatía isquémica, siendo el 58.3 por ciento portadores de resincronizador con o sin cardiodesfibrilador. El 90 por ciento de los pacientes tiene 2 o más medicamentos, 77 por ciento betabloqueador, 90 por ciento iECA o ARA II, 85.7 por ciento algún diurético.Conclusión: se caracterizaron los pacientes que recibieron terapia electrofisiológica para manejo avanzado de falla cardíaca.

Simultaneous and successive inoculations of yeasts and lactic acid bacteria on the fermentation of an unsulfited Tannat grape must

Interactions between yeasts and lactic acid bacteria are strain specific, and their outcome is expected to change in simultaneous alcoholic -malolactic fermentations from the pattern observed in successive fermentations. One Oenococcus oeni strain Lalvin VP41TM was inoculated with two Saccharomyces cerevisiae strains either simultaneously, three days after the yeast inoculation, or when alcoholic fermentation was close to finish. Early bacterial inoculations with each yeast strain allowed for the growth of the bacterial populations, and the length of malolactic fermentation was reduced to six days. Alcoholic fermentation by Lalvin ICV D80® yeast strain left the highest residual sugar, suggesting a negative effect of the bacterial growth and malolactic activity on its performance. In sequential inoculations the bacterial populations did not show actual growth with either yeast strain. In this strategy, both yeast strains finished the alcoholic fermentations, and malolactic fermentations took longer to finish. Lalvin ICV D80® allowed for higher viability and activity of the bacterial strain than Fermicru UY4® under the three inoculation strategies. This was beneficial for the sequential completion of both fermentations, but negatively affected the completion of alcoholic fermentation by Lalvin ICV D80® in the early bacteria additions. Conversely, Fermicru UY4®, which was rather inhibitory towards the bacteria, favored the timely completion of both fermentations simultaneously. As bacteria in early inoculations with low or no SO2 addition can be expected to multiply and interact with fermenting yeasts, not only are the yeast-bacterium strains combination and time point of the inoculation to be considered, but also the amount of bacteria inoculated.

Análisis macroscópico de los tejidos dentales y periodontales de cerdo (Sus domesticus) sometidos a altas temperaturas / Macroscopic analysis of dental and periodontal tissues of pig (Sus domesticus) exposed to high temperatures

Objetivo: Describir los cambios físicos macros-estructurales de los tejidos dentales (esmalte, dentina y cemento) y periodonta - les (mucosa oral, hueso compacto alveolar y hueso esponjoso alveolar) de cerdo doméstico sometidos a altas temperaturas. Materiales y métodos: Se realizó un estudio observacional descriptivo de naturaleza pseudo-experimental in Vitro para observar los cambios físicos macro-estructurales de los tejidos dentales y periodontales en 25 dientes de cerdo doméstico sometidos a altas temperaturas (200ºC, 400ºC, 600ºC, 800ºC, 1000ºC). Resultados: Los tejidos dentales y pe - riodontales estudiados presentan gran resistencia al someterse a altas tempe - raturas sin variar considerablemente su macro-estructura. A 200°C hay cambios de color y aparecen fisuras en esmalte. A 400°C aumentan las fisuras y hay sepa - ración entre los tejidos duros, iniciando la carbonización. A 600°C las fracturas en los tejidos dentales y hueso son más evidentes. A 800°C inicia incineración de los tejidos. A 1000°C no hay evidencia de tejidos blandos, hay estallido de la corona y fragmentación del tejido óseo. Conclusiones: El análisis macroscópico de los dientes de cerdo doméstico articulados en sus respectivas unidades alveolo-den- tarias se constituye en un modelo experi - mental que simula de manera fehaciente el comportamiento de los tejidos dentales y periodontales al ser sometidos a altas temperaturas, sin embargo, se recomienda realizar un estudio en dientes humanos ar - ticulados en su respectiva unidad alveolar, para determinar si dichos cambios se repi- ten y son extrapolables, para ser empleados en procesos de identificación odontológica y documentación de la necropsia médico- legal en el caso de cadáveres o restos huma - nos quemados, carbonizados o incinerados...(Au)

Objective: To describe the physical chan- gesof macro-structural dental tissues (ena- mel, dentin and cement) and periodontal (oral mucous membrane, alveolar compact bone and cancellous alveolar bone) of domestic pig (Sus domesticus) expose to high temperatures. Materials and methods: This descriptive study observed the physical changes in ma - cro-structural dental tissues and periodontal in 25 teeth of domestic pigs subjected to high temperatures (200°C, 400°C, 600°C, 800°C and 1000°C). Results: Dental and periodontal tissues stu - died show great resistance when subjected to high temperatures without changing sig - nificantly their macro-structure. At 200°C no color changes and cracks appear in the enamel. At 400°C there was an increase of the fissure and no separation between the hard tissues, initiating carbonization. At 600°C fractures in the dental tissues and bone are most apparent. At 800°C burning of the tissues initiated. At 1000°C there was no evidence of soft tissue. Conclusions: Macroscopic analysis of the teeth articulated in their alveolar-dental units constitutes a experimental model that ssimulates the changes of dental and perio - dontal tissues expose to high temperature. It is recommended to conduct astudy on human teeth in their respective unit arti- culated alveolar to determine whether the macro-structural physical changes descri- bed are repeated and can be extrapolated, and which can eventually be used during the process of dental identification and documentation of the medical legal autopsy used in the case of bodies or human remains burned, charred and burned...(Au)

Morbimortalidad de los pacientes con cetoacidosis diabética que ingresaron a la unidad de cuidados intensivos pediátricos del Hospital Infantil Universitario de la Cruz Roja, Rafael Henao Toro, de la Ciudad de Manizales (Colombia), 2004-2010 / Morbidity and mortality of patients with diabetic ketoacidosis admitted to the pediatric intensive care unit of the Hospital Infantil Universitario de la Cruz Roja Rafael Henao Toro in Manizales (Colombia), 2004-2010

Objetivo: Estudiar la morbimortalidad de los pacientes admitidos a la Unidad de Cuidados Intensivos Pediátricos del Hospital Infantil Universitario de la Ciudad de Manizales (Colombia) ingresados por cetoacidosis diabética en el período comprendido entre los años 2004 y 2010 (años completos). Materiales y Métodos: Se efectuó un estudio de corte transversal en el cual se analizaron las historias de 72 pacientes de 1 mes a 17 años. Se tomaron variables demográficas y propias de la patología, antecedentes y el tratamiento efectuado. Resultados: El 42,9% presentó acidosis severa, el promedio de edad fue de 10,83 años, 51,4% del género masculino, 46,2% de los pacientes pertenecían a estratos socioeconómicos I y II, 47,2% ingresaron en estado de somnolencia, el 42% con deficiencia en grado leve de bicarbonato y promedio de glicemia de 406 mg/dl. El promedio de días de hospitalización fue de 2,75, el 97,2% de los pacientes no tuvieron complicaciones, en el 29,2% de los casos el factor desencadenante fue infección. Conclusiones: Se puede concluir que con el seguimiento del protocolo para manejo de CAD existente en el Hospital Infantil Universitario de Manizales las complicaciones son poco comunes y la hospitalización en UCIP es corta. Con la instauración de un tratamiento oportuno y precoz el pronóstico de la CAD es bueno. Garantizar la entrega oportuna de medicamentos y planes educativos para los pacientes puede disminuir la incidencia de la CAD...

Supervivencia de implantes realizados en la Clínica CES Sabaneta 2000-2007 / Implant survival in a clinical teaching setting, CES Sabaneta 2000-2007

Introducción y Objetivo: El éxito se define comúnmente como Supervivencia los factores significativos que la influencian.estan relacionados con el paciente, con el implante o con la restauración. El propósito del este estudio fue evaluar la supervivencia de los implantes colocados en la clínica CES Sabaneta entre el 2000 y el2007. Materiales y Métodos: Se tomaron datos de las historias clínicas, se reclutaron el mayor número de pacientes y se evaluaron clínica y radiográficamente Resultados: Entre 2000 y el 2007 se colocaron en la institución 144 implantes en 81 pacientes el (63,9%) fueron mujeres tres casas comerciales principalmente, Nobel Biocare (38,9%), 3i (32,6%) y Lifecore (22,9%). Dado que hubo un alto número de pacientes que no pudieron ser contactados, se asumió el tiempo hasta la fecha de última revisión del implante, como tiempo de supervivencia del mismo y se estableció la diferencia en tiempo de uperviviencia de los implantes en estos pacientes con respecto a la supervivencia de los implantes en los pacientes contactados, no se encontraron diferencias estadísticamente significativas en el promedio del tiempo de supervivencia de los implantes. El promedio en el tiempo desde la colocación de los implantes hasta el análisis fue de 5 años aproximadamente, el éxito fue del 89,6%, es decir de los 144 implantes colocados se presentaron 15 fracasos. Conclusión: La supervivencia de los implantes colocados en la Clínica CES Sabaneta, está de acuerdo a los reportes en la literatura tanto de instituciones educativas como privadas.

Introduction and Objetive: The success of dental implants is commonly defined as survival and there are significant factors that influence it. Some of these are related to the patient, others with the implant and finally with the restoration. Materials and Methods: The purpose of this study was to evaluate the survival of implants placed in the CES University Dental Clinics between 2000 and 2007. Results: Data was collected from the medical records of as many patients possible and found that during this period 144 implants in 81 patients were placed. Most patients were female (63,9%), Implants placed corresponded to Nobel Biocare (38,9%), 3i (32,6%) and Lifecore (22,9%), and the remaining percentage from other commercial brands. Conclusions: Average time from implant placement until the analysis was approximately 5 years with a success rate of 89,6%, which means that out of 144 implants presented 15 were missing. It can be concluded that the survival of implants placed at CES University Dental Clinics coincides with reports in the literature as well as private educational institutions.

Electrotonic myofibroblast-to-myocyte coupling increases propensity to reentrant arrhythmias in two-dimensional cardiac monolayers.

In pathological conditions such as ischemic cardiomyopathy and heart failure, differentiation of fibroblasts into myofibroblasts may result in myocyte-fibroblast electrical coupling via gap junctions. We hypothesized that myofibroblast proliferation and increased heterocellular coupling significantly alter two-dimensional cardiac wave propagation and reentry dynamics. Co-cultures of myocytes and myofibroblasts from neonatal rat ventricles were optically mapped using a voltage-sensitive dye during pacing and sustained reentry. The myofibroblast/myocyte ratio was changed systematically, and junctional coupling of the myofibroblasts was reduced or increased using silencing RNAi or adenoviral overexpression of Cx43, respectively. Numerical simulations in two-dimensional models were used to quantify the effects of heterocellular coupling on conduction velocity (CV) and reentry dynamics. In both simulations and experiments, reentry frequency and CV diminished with larger myofibroblast/myocyte area ratios; complexity of propagation increased, resulting in wave fractionation and reentry multiplication. The relationship between CV and coupling was biphasic: an initial decrease in CV was followed by an increase as heterocellular coupling increased. Low heterocellular coupling resulted in fragmented and wavy wavefronts; at high coupling wavefronts became smoother. Heterocellular coupling alters conduction velocity, reentry stability, and complexity of wave propagation. The results provide novel insight into the mechanisms whereby electrical myocyte-myofibroblast interactions modify wave propagation and the propensity to reentrant arrhythmias.

Adenoviral expression of IKs contributes to wavebreak and fibrillatory conduction in neonatal rat ventricular cardiomyocyte monolayers.

Previous studies have shown that the gating kinetics of the slow component of the delayed rectifier K(+) current (I(Ks)) contribute to postrepolarization refractoriness in isolated cardiomyocytes. However, the impact of such kinetics on arrhythmogenesis remains unknown. We surmised that expression of I(Ks) in rat cardiomyocyte monolayers contributes to wavebreak formation and facilitates fibrillatory conduction by promoting postrepolarization refractoriness. Optical mapping was performed in 44 rat ventricular myocyte monolayers infected with an adenovirus carrying the genomic sequences of KvLQT1 and minK (molecular correlates of I(Ks)) and 41 littermate controls infected with a GFP adenovirus. Repetitive bipolar stimulation was applied at increasing frequencies, starting at 1 Hz until loss of 1:1 capture or initiation of reentry. Action potential duration (APD) was significantly shorter in I(Ks)-infected monolayers than in controls at 1 to 3 Hz (P<0.05), whereas differences at higher pacing frequencies did not reach statistical significance. Stable rotors occurred in both groups, with significantly higher rotation frequencies, lower conduction velocities, and shorter action potentials in the I(Ks) group. Wavelengths in the latter were significantly shorter than in controls at all rotation frequencies. Wavebreaks leading to fibrillatory conduction occurred in 45% of the I(Ks) reentry episodes but in none of the controls. Moreover, the density of wavebreaks increased with time as long as a stable source sustained the fibrillatory activity. These results provide the first demonstration that I(Ks)-mediated postrepolarization refractoriness can promote wavebreak formation and fibrillatory conduction during pacing and sustained reentry and may have important implications in tachyarrhythmias.

Kir2.3 isoform confers pH sensitivity to heteromeric Kir2.1/Kir2.3 channels in HEK293 cells.

BACKGROUND: Data on pH regulation of the cardiac potassium current I(K1) suggest species-dependent differences in the molecular composition of the underlying Kir2 channel proteins. OBJECTIVE: The purpose of this study was to test the hypothesis that the presence of the Kir2.3 isoform in heterotetrameric channels modifies channel sensitivity to pH. METHODS: Voltage clamp was performed on HEK293 cells stably expressing guinea pig Kir2.1 and/or Kir2.3 isoforms and on sheep cardiac ventricular myocytes at varying extracellular pH (pH(o)) and in the presence of CO(2) to determine the sensitivity of macroscopic currents to pH. Single-channel activity was recorded from the HEK293 stables to determine the mechanisms of the changes in whole cell current. RESULTS: Biophysical characteristics of whole-cell and single-channel currents in Kir2.1/Kir2.3 double stables displayed properties attributable to isoform heteromerization. Whole-cell Kir2.1/Kir2.3 currents rectified in a manner reminiscent of Kir2.1 but were significantly inhibited by extracellular acidification in the physiologic range (pK(a) approximately 7.4). Whole-cell currents were more sensitive to a combined extracellular and intracellular acidification produced by CO(2). At pH(o) = 6.0, unitary conductances of heteromeric channels were reduced. Ovine cardiac ventricular cell I(K1) was pH(o) and CO(2) sensitive, consistent with the expression of Kir2.1 and Kir2.3 in this species. CONCLUSION: Kir2.1 and Kir2.3 isoforms form heteromeric channels in HEK293. The presence of Kir2.3 subunit(s) in heteromeric channels confers pH sensitivity to the channels. The single and double stable cells presented in this study are useful models for studying physiologic regulation of heteromeric Kir2 channels in mammalian cells.

Efectos del peróxido de carbamida al 10 por ciento en el órgano dentino pulpar de premolares sanos utilizado por un periodo de 8 y 15 días / Efects of carbamide peroxide to 10% in the dentine pulpar organ used in healthy premolars for a period of 8 and 15 days

Se han realizado numerosos estudios sobre la sensibilidad causada por las técnicas de blanqueamiento vital debido a la respuesta pulpar generada por la difusión de iones de bajo peso molecular del peróxido de carbamida y la urea a través del esmalte, pocos estudios han evaluado el efecto que dicha técnica puede generar sobre las estructuras del órgano dentino pulpar, por lo tanto el objetivo de este estudio fue evaluar el efecto in vivo del peróxido de carbamida al 10 por ciento sobre el órgano dentino pulpar en pacientes sometidos a tratamiento de blanqueamiento durante periodos de 8 y 15 días. Se utilizaron 30 premolares sanos con extracción indicada por motivos ortodónticos. Los dientes fueron elegidos al azar para ser tratados como grupo control o como grupo de estudio en periodos de 8 o 15 días. Las muestras se dividieron en 3 grupos: grupo de control (con flúor neutro), grupo de 8 días y grupo de 15 días (con peroxido de carbamida al 10 por ciento). Posteriormente, una vez realizada la exodoncia fueron sometidos a manejo histológico y tinción con hematoxilina -eosina, y tricrómico de Masson conel fin de evaluar cambios estructurales. No se encontraron diferencias significativas en cuanto a los efectos que se podrían esperar por el blanqueamiento y el tiempo de exposición al material blanqueador, así como no se encontraron diferencias entre los hallazgos en los cortes del grupo de control y los grupos experimentales sometidos al peróxido de carbamida al 10 por ciento (NuproGold ® Dentsply)...

From mouse to whale: a universal scaling relation for the PR Interval of the electrocardiogram of mammals.

BACKGROUND: On the ECG, the PR interval measures the time taken by an electrical impulse generated in the sinoatrial node to propagate from atria to ventricles. From mouse to whale, the PR interval increases approximately 10(1), whereas body mass (BM) augments approximately 10(6). Scaling of many biological processes (eg, metabolic rate, life span, aortic diameter) is described by the allometric equation Y=Y(0) x BM(b), where Y is the biological process and b is the scaling exponent that is an integer multiple of 1/4. Hierarchical branching networks have been proposed to be the underlying mechanism for the 1/4 power allometric law. METHODS AND RESULTS: We first derived analytically the allometric equation for the PR interval. We assumed that the heart behaves as a set of "fractal-like" networks that tend to minimize propagation time across the conducting system while ensuring a hemodynamically optimal atrioventricular activation sequence. Our derivation yielded the relationship PR proportional, variant BM1/4. We subsequently obtained previously published values of PR interval, heart rate, and BM of 541 mammals representing 33 species. Double-logarithmic analysis demonstrates that PR interval increases as heart rate decreases, and both variables relate to BM following the 1/4 power law. Most important, the best fit for PR versus BM is described by the equation PR=53 x BM0.24. Hence, the empirically determined exponent (0.24) is close to 1/4, as predicted. CONCLUSIONS: We have demonstrated that the PR interval of mammals scales as the 1/4 power of the BM, following the universal law for allometric scaling to ensure an optimal atrioventricular activation sequence.