Experimental and Theoretical Brownian Dynamics Analysis of Ion Transport During Cellular Electroporation of E. coli Bacteria.

Escherichia coli bacterium is a rod-shaped organism composed of a complex double membrane structure. Knowledge of electric field driven ion transport through both membranes and the evolution of their induced permeabilization has important applications in biomedical engineering, delivery of genes and antibacterial agents. However, few studies have been conducted on Gram-negative bacteria in this regard considering the contribution of all ion types. To address this gap in knowledge, we have developed a deterministic and stochastic Brownian dynamics model to simulate in 3D space the motion of ions through pores formed in the plasma membranes of E. coli cells during electroporation. The diffusion coefficient, mobility, and translation time of Ca2+, Mg2+, Na+, K+, and Cl- ions within the pore region are estimated from the numerical model. Calculations of pore's conductance have been validated with experiments conducted at Gustave Roussy. From the simulations, it was found that the main driving force of ionic uptake during the pulse is the one due to the externally applied electric field. The results from this work provide a better understanding of ion transport during electroporation, aiding in the design of electrical pulses for maximizing ion throughput, primarily for application in cancer treatment.

Síndrome de Grebe: Reporte de un caso / Grebe syndrome. Case report

La condrodisplasia de Grebe es un trastorno raro autosómico recesivo que pertenece al grupo de las osteocondrodisplasias. Clínicamente se caracteriza por un severo dismorfismo con una marcada micromelia y deformidad de las extremidades inferiores y superiores. Conocer este tipo de síndrome orienta a dar mejores diagnósticos y permite el diagnóstico diferencial con patologías más comunes, como la acondroplasia. Se presenta una paciente de 35 años con diagnóstico de síndrome de Grebe desde los 10 años. El síndrome de Grebe tiene una muy baja incidencia; por este motivo, es poco conocido por el cuerpo médico en general y aun menos para los ortopedistas, quienes serán los encargados de tratar a estos pacientes. Nivel de Evidencia: IV

Grebe syndrome is a rare autosomal recessive disorder that belongs to the group of osteochondrodysplasias. Clinically, it is characterized by severe dysmorphism, marked micromelia and deformities of the lower and upper limbs. Recognition of this syndrome allows to give better diagnoses and to establish a differential diagnosis with more common pathologies, such as achondroplasia. We present a 35-year-old woman with diagnosis of Grebe syndrome at the age of 10. Grebe syndrome has a very low incidence; therefore, it is unknown by general physicians and still less by orthopedic surgeons, who will treat these patients. Level of Evidence: IV