Electrical Communication in Lymphangions.

Contractions of lymphangions, i.e., the segment between two one-way lymphatic valves, generate the pressure gradients that propel lymph back to the circulation. Each lymphangion is comprised of an inner sheet of lymphatic endothelial cells circumscribed by one or more layers of lymphatic muscle cells (LMCs). Each contraction is produced by an LMC action potential (AP) that propagates via gap junctions along the lymphangion. Yet, electrical coupling within and between cell layers and the impact on AP waves is poorly understood. Here, we combine studies in rat and mouse lymphatic vessels with mathematical modeling to show that initiation of AP waves depends on high input resistance (low current drain), whereas propagation depends on morphology and sufficient LMC:LMC coupling. Simulations show that 1) myoendothelial coupling is insignificant to facilitate AP generation and sustain an experimentally measured cross-junctional potential difference of 25 mV, i.e., AP waves propagate along the LMC layer only; 2) LMC:LMC resistance is estimated around 2-10 MΩ but depends on vessel structure and cell-cell coupling, e.g., some degree of LMC overlap protects AP waves against LMC decoupling; 3) the propensity of AP wave initiation is highest around the valves, where the density of LMCs is low; and 4) a single pacemaker cell embedded in the LMC layer must be able to generate very large currents to overcome the current drain from the layer. However, the required current generation to initiate an AP wave is reduced upon stimulation of multiple adjacent LMCs. With stimulation of all LMCs, AP waves can also arise from heterogeneity in the electrical activity of LMCs. The findings advance our understanding of the electrical constraints that underlie initiation of APs in the LMC layer and make testable predictions about how morphology, LMC excitability, and LMC:LMC electrical coupling interact to determine the ability to initiate and propagate AP waves in small lymphatic vessels.

Relación del aislamiento microbiano en líquido amniótico con la sepsis neonatal / Relationship of the microbial isolate in amniotic fluid with the neonatal sepsis

Muchas infecciones adquiridas por el recién nacido durante el nacimiento son el resultado de la aspiración de líquido amniótico infectado o de las secreciones vaginales de la madre Objetivo: Establecer la relación entre el aislamiento bacteriano en el líquido amniótico y el desarrollo de sepsis neonatal y vincular las roturas prematuras de membranas, el empleo de antimicrobianos maternos y el peso al nacer con la aparición de sepsis en el neonato. Método: Se realizó un estudio longitudinal prospectivo en los servicios de microbiología, perinatología y neonatología del Hospital Ginecobstétrico Provincial Docente Ana Betancourt de Mora de Camagüey, desde octubre de 2006 hasta marzo de 2007. Se recibieron un total de 65 muestras de líquido amniótico las cuales fueron procesadas en el laboratorio de Microbiología según las normas vigentes. Resultados: Los microorganismos del género Enterococo fueron aislados con mayor frecuencia 37,14 por ciento. En el 88,5 por ciento de las pacientes con rotura prematura de membranas más de 72 horas se desarrolló sepsis congénita en los niños. La mayoría de las madres con tratamiento antimicrobiano profiláctico no tuvieron hijos con sepsis congénita. Existió una estrecha relación entre el bajo peso al nacer < 2500 g y la sepsis neonatal. Conclusiones: El uso de antimicrobianos profiláctico en la rotura prematura de membranas disminuye el riesgo de sepsis neonatal(AU)

Many acquired infections by the newborn during birth are the result of the aspiration of infected amniotic fluid or of mother's vaginal secretions. Objective: To establish the relationship among the bacterial isolate in the amniotic fluid and the development of neonatal sepsis and to link the premature ruptures of membranes, the employment of maternal antimicrobial and the birthweight with sepsis apparition in the neonate. Method: A longitudinal prospective study in the microbiology, perinatology and neonatology services of the Teaching Provincial Gynecobstetric Hospital Ana Betancourt de Mora of Camagüey was conducted, from October 2006 to March 2007. A total of 65 samples of amniotic fluid were received which were processed in the laboratory of Microbiology according to the effective norms. Results: The microorganisms of the genus Enterococo was isolated with more frequency 37,14 percent. In the 88,5 percent of patients with premature rupture of membranes more than 72 hours was developed congenital sepsis in the children. The majority of mothers with prophylactic antimicrobial treatment didn't have children with congenital sepsis. A narrow relationship existed among the low birth weight < 2500 g and the neonatal sepsis. Conclusions: The use of prophylactic antimicrobial in the premature rupture of membranes diminishes the risk of neonatal sepsis(AU)

Relación del aislamiento microbiano en líquido amniótico con la sepsis neonatal / Relationship of the microbial isolate in amniotic fluid with the neonatal sepsis

Muchas infecciones adquiridas por el recién nacido durante el nacimiento son el resultado de la aspiración de líquido amniótico infectado o de las secreciones vaginales de la madre Objetivo: Establecer la relación entre el aislamiento bacteriano en el líquido amniótico y el desarrollo de sepsis neonatal y vincular las roturas prematuras de membranas, el empleo de antimicrobianos maternos y el peso al nacer con la aparición de sepsis en el neonato. Método: Se realizó un estudio longitudinal prospectivo en los servicios de microbiología, perinatología y neonatología del Hospital Ginecobstétrico Provincial Docente Ana Betancourt de Mora de Camagüey, desde octubre de 2006 hasta marzo de 2007. Se recibieron un total de 65 muestras de líquido amniótico las cuales fueron procesadas en el laboratorio de Microbiología según las normas vigentes. Resultados: Los microorganismos del género Enterococo fueron aislados con mayor frecuencia 37,14 por ciento. En el 88,5 por ciento de las pacientes con rotura prematura de membranas más de 72 horas se desarrolló sepsis congénita en los niños. La mayoría de las madres con tratamiento antimicrobiano profiláctico no tuvieron hijos con sepsis congénita. Existió una estrecha relación entre el bajo peso al nacer < 2500 g y la sepsis neonatal. Conclusiones: El uso de antimicrobianos profiláctico en la rotura prematura de membranas disminuye el riesgo de sepsis neonatal.

Many acquired infections by the newborn during birth are the result of the aspiration of infected amniotic fluid or of mother's vaginal secretions. Objective: To establish the relationship among the bacterial isolate in the amniotic fluid and the development of neonatal sepsis and to link the premature ruptures of membranes, the employment of maternal antimicrobial and the birthweight with sepsis apparition in the neonate. Method: A longitudinal prospective study in the microbiology, perinatology and neonatology services of the Teaching Provincial Gynecobstetric Hospital Ana Betancourt de Mora of Camagüey was conducted, from October 2006 to March 2007. A total of 65 samples of amniotic fluid were received which were processed in the laboratory of Microbiology according to the effective norms. Results: The microorganisms of the genus Enterococo was isolated with more frequency 37,14 percent. In the 88,5 percent of patients with premature rupture of membranes more than 72 hours was developed congenital sepsis in the children. The majority of mothers with prophylactic antimicrobial treatment didn't have children with congenital sepsis. A narrow relationship existed among the low birth weight < 2500 g and the neonatal sepsis. Conclusions: The use of prophylactic antimicrobial in the premature rupture of membranes diminishes the risk of neonatal sepsis.