Transthoracic cardiac ultrasonic stimulation induces a negative chronotropic effect.

The objective of this study is to investigate cardiac bioeffects resulting from ultrasonic stimulation using a specific set of acoustical parameters. Ten Sprague-Dawley rats were anesthetized and exposed to 1-MHz ultrasound pulses of 3-MPa peak rarefactional pressure and approximately 1% duty factor. The pulse repetition frequency started slightly above the heart rate and was decreased by 1 Hz every 10 s, for a total exposure duration of 30 s. The control group was composed of five rats. Two-way analysis of variance for repeated measures and Bonferroni post hoc tests were used to compare heart rate and ejection fraction, which was used as an index of myocardial contractility. It was demonstrated for the first time that transthoracic ultrasound has the potential to decrease the heart rate by ~20%. The negative chronotropic effect lasted for at least 15 min after ultrasound exposure and there was no apparent gross damage to the cardiac tissue.

Experience of a pediatric HIV clinic in Guatemala City.

OBJECTIVES: To describe the clinical experience of a Guatemalan pediatric HIV clinic and referral center, and fill the gap in literature available on pediatric HIV in Guatemala, a country facing a growing HIV epidemic. METHODS: Analyses were performed on data available from the clinical databases maintained by the Clínica Familiar Luis Angel García within the Hospital General San Juan de Dios in Guatemala City, Guatemala. RESULTS: From January 1997-June 2006, a total of 536 children (individuals under 13 years of age) were registered at the clinic, 54% of them female. At the initial visit, 241 were known to be HIV infected, while 295 were known to have been exposed to HIV, but were of undetermined infection status. Of the 295 with undetermined status, serostatus was determined in 173, and 57 (33%) were HIV positive. The patients came from all 24 departments of Guatemala, but the majority (64%) was from Guatemala City. Most had perinatal exposure; three patients had been sexually exposed to HIV (all male); and the mode of infection could not be determined for six children. In the cohort of children whose infection status was initially undetermined, the provision of antiretroviral (ARV) medication (both pre- and neonatal), in addition to Cesarean section, was associated with an odds ratio of 0.06 for HIV infection (P < 0.001) when compared to children who had no interventions. Highly active antiretroviral therapy (HAART) was administered to 167 HIV-infected children. There were 44 known deaths in this cohort; no deaths occurred among the children who were not infected. CONCLUSIONS: Pediatric HIV/AIDS is present in all parts of Guatemala. Programs to prevent mother to child transmission and to provide appropriate treatment to families living with HIV/AIDS must be a public health priority.

Experience of a pediatric HIV clinic in Guatemala City / Experiencia de una clínica pediátrica para el VIH en la Ciudad de Guatemala

OBJECTIVES: To describe the clinical experience of a Guatemalan pediatric HIV clinic and referral center, and fill the gap in literature available on pediatric HIV in Guatemala, a country facing a growing HIV epidemic. METHODS: Analyses were performed on data available from the clinical databases maintained by the Clínica Familiar Luis ángel García within the Hospital General San Juan de Dios in Guatemala City, Guatemala. RESULTS: From January 1997-June 2006, a total of 536 children (individuals under 13 years of age) were registered at the clinic, 54 percent of them female. At the initial visit, 241 were known to be HIV infected, while 295 were known to have been exposed to HIV, but were of undetermined infection status. Of the 295 with undetermined status, serostatus was determined in 173, and 57 (33 percent) were HIV positive. The patients came from all 24 departments of Guate mala, but the majority (64 percent) was from Guatemala City. Most had perinatal exposure; three patients had been sexually exposed to HIV (all male); and the mode of infection could not be determined for six children. In the cohort of children whose infection status was initially undetermined, the provision of antiretroviral (ARV) medication (both pre- and neonatal), in addition to Cesarean section, was associated with an odds ratio of 0.06 for HIV infection (P < 0.001) when compared to children who had no interventions. Highly active antiretroviral therapy (HAART) was administered to 167 HIV-infected children. There were 44 known deaths in this cohort; no deaths occurred among the children who were not infected. CONCLUSIONS: Pediatric HIV/AIDS is present in all parts of Guatemala. Programs to prevent mother to child transmission and to provide appropriate treatment to families living with HIV/AIDS must be a public health priority.

OBJETIVOS: Describir la experiencia de una clínica y centro de referencia pediátrico para el VIH en Guatemala y llenar el vacío existente en la literatura científica sobre la infección pediátrica por el VIH en ese país, donde se enfrenta una creciente epidemia por el VIH. MÉTODOS: SE analizaron los datos disponibles en la base de datos clínicos de la Clínica Familiar Luis Ángel García del Hospital General San Juan de Dios, Ciudad de Guatemala, Guatemala. RESULTADOS: Entre enero de 1997 y junio de 2006 en la clínica se registraron 536 menores de 13 años; 54 por ciento de los cuales eran niñas. En la visita inicial se sabía que 241 estaban infectados por el VIH y que 295 habían estado expuestos a ese virus aunque su diagnóstico era indeterminado. De estos, se determinó el estatus serológico de 173, de los cuales 57 (33 por ciento) resultaron positivos al VIH. Los pacientes procedían de los 24 departamentos de Guatemala, pero la mayoría (64 por ciento) era de la Ciudad de Guatemala. La mayoría de los pacientes había estado expuestos al VIH por la vía perinatal; tres pacientes (todos varones), por la vía sexual y no se pudo determinar la vía de infección de seis niños. En la cohorte de niños con diagnóstico inicial indeterminado, el tratamiento antirretroviral (tanto pre como posnatal) junto con el nacimiento por cesárea se asociaron con una razón de posibilidades (odds ratio) de tener la infección por el VIH de 0,06 (P < 0,001) en comparación con los niños sin estas intervenciones. El tratamiento antirretroviral de gran actividad (HAART) se administró a 167 niños infectados por el VIH. Se registraron 44 muertes en esta cohorte, ninguna en los niños sin infección. CONCLUSIONES: La infección pediátrica por VIH/sida está presente en todos los departamentos de Guatemala. Los programas para evitar la transmisión de madre a hijo y brindar el tratamiento adecuado a las familias que viven con VIH/sida son una prioridad de salud pública.

Materiales dentales y su selección

Naturaleza y manipulación de los materiales. Uniones atómicas. Propiedades físicas y mecánicas. Color y aspecto. Fenómenos de superficie y adhesión. Materiales derivados del yeso. Introducción a los polímeros. Polímeros de acrílico y BIs-GMA. Materiales para protectores bucales. Acondicionadores de tejidos y materiales para rebasado de prótesis. Materiales para impresión. Barnices y recubrimientos cavitarios. Cementos dentales. Cementos de silicato. Porcelanas dentales. Estructura de metales y aleaciones. Amalgama. Toxicidad del mercurio. Orificaciones. Aleaciones para colados sobre la base de materiales preciosos. Ceras. Revestimientos para el colado de incrustaciones. Colados de oro. Aleaciones metálicas para bases de prótesis. Revestimiento para altas temperaturas. Alambres para ortodoncia. Soldaduras. Abrasión y pulido. Materiales sintéticos para implantes. Selección de los materiales dentales. Aplicación de los materiales dentales. Respuestas biológicas. Comportamiento clínico. Solución de problemas. Valores tabulados de propiedades físicas y mecánicas. Guía de productos y materiales dentales. Longevidad de las restauraciones usuadas comúnmente en odontología. Tabla periódica de los elementos. Unidades y factores de conversión