Disyunción maxilar rápida asistida con microtornillos en pacientes en crecimiento con deficiencia maxilar transversal / Miniscrew assisted rapid maxillary expansion in growing patients with transverse maxillary deficiency

RESUMEN: Introducción: La disyunción maxilar rápida tradicional (RME) ha sido el tratamiento de elección para corregir la maloclusión secundaria a la deficiencia maxilar transversal. Debido a las complicaciones que pueden presentar los pacientes, se han desarrollado técnicas de disyunción maxilar asistida por microtornillos (MARPE). Sin embargo, aún no hay consenso respecto a los reales beneficios de la disyunción maxilar rápida asistida por microtornillos por sobre la disyunción tradicional en pacientes jóvenes y en crecimiento. Métodos: Realizamos una búsqueda en Epistemonikos, la mayor base de datos de revisiones sistemáticas en salud, la cual es mantenida mediante el cribado de múltiples fuentes de información, incluyendo MEDLINE, EMBASE, Cochrane, entre otras. Extrajimos los datos desde las revisiones identificadas, analizamos los datos de los estudios primarios, realizamos un metanálisis y preparamos una tabla de resumen de los resultados utilizando el método GRADE. Resultados y conclusiones: Identificamos siete revisiones sistemáticas que en conjunto incluyeron seis estudios primarios, de los cuales todos corresponden a ensayos aleatorizados. Concluimos que: la disyunción maxilar rápida asistida por microtornillos (MARPE) probablemente disminuye la pérdida de hueso alveolar bucal y la resistencia de la vía aérea nasal en comparación a la disyunción maxilar rápida tradicional (RME) (certeza evidencia moderada). MARPE podría disminuir la inclinación dentaria y resultar en poca o nula diferencia en la percepción de dolor en comparación con RME (certeza de la evidencia baja). No es posible establecer con claridad si MARPE aumenta la expansión maxilar en comparación con RME, debido a que la certeza de la evidencia ha sido evaluada como muy baja.

ABSTRACT: Introduction: Traditional rapid maxillary expansion (RME) has been the gold-standard treatment to correct malocclusion secondary to transverse maxillary deficiency. Due to related complications, mini screw assisted maxillary expansion (MARPE) techniques have been developed. However, there is no consensus regarding the benefits of mini screw assisted maxillary expansion over traditional expansion in young and growing patients. Methods: We searched in Epistemonikos, the largest database of systematic reviews in health, which is maintained by screening multiple information sources, including MEDLINE, EMBASE, Cochrane, among others. We extracted data from the systematic reviews, reanalyzed data of primary studies, conducted a meta-analysis and generated a summary of findings table using the GRADE approach. Results and conclusions: We identified seven systematic reviews including six studies overall, all of which were randomized trials. We concluded that mini screw maxillary expansion (MARPE) probably reduces buccal alveolar bone and nasal airway resistance compared to traditional rapid maxillary expansion (RME). MARPE may reduce dental inclination and result in little or no difference in pain perception compared to RME. We are uncertain whether MARPE improves maxillary expansion compared to RME, as the certainty of the evidence has been assessed as very low.

Iron and glutathione at the crossroad of redox metabolism in neurons

Neurons, as non-dividing cells, encounter a myriad of stressful conditions throughout their lifespan. In particular, there is increasing evidence that iron progressively accumulates in the brain with age and that iron-induced oxidative stress is the cause of several forms of neurodegeneration. Here, we review recent evidence that gives support to the following notions: 1) neuronal iron accumulation leads to oxidative stress and cell death; 2) neuronal survival to iron accumulation associates with decreased expression of the iron import transporter DMT1 and increased expression of the efflux transporter IREG1; and 3) the adaptive process of neurons towards iron-induced oxidative stress includes a marked increase in both the expression of the catalytic subunit of gamma glutamate-cysteine ligase and glutathione. These findings may help to understand aging-related neurodegeneration hallmarks: oxidative damage, functional impairment and cell death.

Redox regulation of calcium release in skeletal and cardiac muscle

In skeletal and cardiac muscle cells, specific isoforms of the Ryanodine receptor channels mediate Ca2+ release from the sarcoplasmic reticulum. These channels are highly susceptible to redox modifications, which regulate channel activity. In this work, we studied the effects of Ca2+ (endogenous agonist) and Mg2+ (endogenous inhibitor) on the kinetics of Ca2+ release from sarcoplasmic reticulum vesicles isolated from skeletal or cardiac mammalian muscle. Native skeletal vesicles exhibited maximal stimulation of release kinetics by 10-20 microM [Ca2+], whereas in native cardiac vesicles, maximal stimulation of release required only 1 microM [Ca2+]. In 10 microM [Ca2+], free [Mg2+] < 0.1 mM produced marked inhibition of release from skeletal vesicles but free [Mg2+] < or = 0.8 mM did not affect release from cardiac vesicles. Incubation of skeletal or cardiac vesicles with the oxidant thimerosal increased their susceptibility to stimulation by Ca2+ and decreased the inhibitory effect of Mg2+ in skeletal vesicles. Sulfhydryl-reducing agents fully reversed the effects of thimerosal. The endogenous redox species, glutathione disulfide and S-nitrosoglutathione, also stimulated release from skeletal sarcoplasmic reticulum vesicles. In 10 microM [Ca2+], 35S-nitrosoglutathione labeled a protein fraction enriched in release channels through S-glutathiolation. Free [Mg2+] 1 mM or decreasing free [Ca2+] to the nM range prevented this reaction. Possible physiological and pathological consequences of redox modification of release channels on Ca2+ signaling in heart and muscle cells are discusse