We tested the hypothesis that cells of ventilator-injured lungs are subject to reversible plasma membrane stress failure. Rat lungs were perfused with the membrane impermeable fluorescent marker propidium iodide and randomized to one of four ventilation strategies. Subpleural lung regions were imaged with confocal microscopy, and cell injury was quantified as the number of propidium iodide-positive cells per alveolus. The number of injured cells was significantly greater in lungs ventilated with large tidal volumes and zero end-expiratory pressure than in lungs ventilated with small tidal volumes and positive end-expiratory pressure (p < 0.01). Cell injury correlated with lung weight gain, change in dynamic compliance, and histologic injury scores. In a second set of experiments, lungs were mechanically ventilated for 30 minutes at high tidal volume settings, whereas propidium iodide was perfused either during or after injurious ventilation. Labeling after removal of injurious stress revealed significantly fewer injured cells (0.25 +/- 0.09 to 0.08 +/- 0.08, p < 0.01). We conclude that cells of ventilator-injured lungs are subject to reversible plasma membrane stress failure.

The objective of this study was to assess the effects of hypercapnic acidosis on lung cell injury and repair by confocal microscopy in a model of ventilator-induced lung injury. Three groups of normocapnic, hypocapnic, and hypercapnic rat lungs were perfused ex vivo, either during or after injurious ventilation, with a solution containing the membrane-impermeant label propidium iodide. In lungs labeled during injurious ventilation, propidium iodide fluorescence identifies all cells with plasma membrane wounds, both permanent and transient, whereas in lungs labeled after injurious ventilation propidium iodide fluorescence identifies only cells with permanent plasma membrane wounds. Hypercapnia minimized the adverse effects of high-volume ventilation on vascular barrier function, whereas hypocapnia had the opposite effect. Despite CO 2 -dependent differences in lung mechanics and edema the number of injured subpleural cells per alveolus was similar in the three groups (0.48 Ϯ 0.34 versus 0.51 Ϯ 0.19 versus 0.43 Ϯ 0.20 for hypocapnia, normocapnia, and hypercapnia, respectively). However, compared with normocapnia the probability of wound repair was significantly reduced in hypercapnic lungs (63 versus 38%; p Ͻ 0.02). This finding was subsequently confirmed in alveolar epithelial cell scratch models. The potential relevance of these observations for lung inflammation and remodeling after mechanical injury is discussed.Keywords: permissive hypercapnia; plasma membrane wounding and repair; ventilator-induced lung injury So-called lung protective mechanical ventilation strategies emphasize lung recruitment and the avoidance of large tidal volumes. Such strategies are often associated with hypercapnic acidosis. Many experts view "permissive hypercapnia" as a necessary evil of a low tidal ventilation strategy (1). Concern about detrimental effects of acidemia on renal and cardiovascular function have motivated attempts to enhance CO 2 removal by tracheal gas insufflation (2) and have led to unsubstantiated recommendations about the use of bicarbonate buffers in hypercapnic patients (3). More recent data suggest that hypercapnia may actually protect the lung from certain manifestations of ischemiareperfusion, endotoxin, and mechanical ventilation-related injury (4-9). Hypocapnia, in contrast, and correction of acidemia may be harmful (10-12). The specific mechanisms through which hypercapnia influences lung injury and vascular barrier function remain uncertain (13). CO 2 generates H ϩ ions, which react with titratable groups in certain amino acids and/or interacts directly (Received in original form September 3, 2003; accepted in final form January 21, 2005) Supported by grants from the National Institutes of Health (HL-63178), GlaxoSmithKline, and the Brewer Foundation. with free amine groups in proteins to form carbamate residues (14-16). CO 2 -dependent effects on the generation of reactive oxygen species and reactive nitrogen species as well as effects on ion channel conductivity have all been considered (17, 18).V...

With the use of magnetic twisting cytometry, we characterized the mechanical properties of rat type II alveolar epithelial (ATII) cells in primary culture and examined whether the cells' state of differentiation and the application of deforming stresses influence their resistance to shape change. Cells were harvested from rat lungs as previously described (Dobbs LG. Am J Physiol Lung Cell Mol Physiol 258: L134-L147, 1990) and plated at a density of 1 x 10(6) cells/cm(2) in fibronectin-coated 96 Remova wells, and their mechanical properties were measured 2-9 days later. We show 1) that ATII cells form much stronger bonds with RGD-coated beads than they do with albumin- or acetylated low-density lipoprotein-coated beads, 2) that RGD-mediated bonds seemingly "mature" during the first 60 min of bead contact, 3) that the apparent stiffness of ATII cells increases with days in culture, 4) that stiffness falls when the RGD-coated beads are intermittently oscillated at 0.3 Hz, and 5) that this fall cannot be attributed to exocytosis-related remodeling of the subcortical cytoskeleton. Although the mechanisms of force transfer between basement membrane, cytoskeleton, and plasma membrane of ATII cells remain to be resolved, such analyses undoubtedly require definition of the cell's mechanical properties. To our knowledge, the results presented here provide the first data on this topic.

No abstract

Se estudiaron 103 pacientes y 41 miembros del personal médico y paramédico de tres centros de hemodiálisis en Lima, Perú, para determinar infección por hepatitis B. El antigeno de superficie de la hepatitis B(HBsAg) fue detectado en 21.36% de los pacientes y2.4% del personal. El anticuerpo de superficie (antiHBs) en 47.57% respectivamente. Las determinaciones de hicieron por el método de ELISA. En los pacientes la presencia de ambos marcadores no se relacionó a las transfusiones sanguíneas. El HBsAg se encontró con mayor frecuencia en los que se encontraban en los dos primeros años de hemodiálisis, en aquellos con antecedente de ictericia o hepatitis, en los que tuvieron transaminasas por encima del valor normal, y en aquellos cuya enfermedad renal de fondo se desconocía. En el personal, el antiHBs se encontró más frecuentemente entre los que tenía mayor tiempo de trabajo en las unidades de hemodiálisis y ambos marcadores fueron negativos en los que negaron antecedente de inoculación accidental.

Los objetivos de este estudio fueron: 1) describir las actividades sexuales parafílicas en Puerto Rico, identificando las diferencias entre fantasías, deseos y comportamientos de parafilias específica, 2) explorar si existian relaciones entre las fantasías sexuales y la actuación (comportamiento) de estas fantasías, 3 ) explorar la satisfacción con la vida, la salud mental y las preocupaciones sobre la conducta sexual de quienes reportaron conductas parafílicas, y 4) describir los sentimientos durante y después de tener fantasías, deseos y/o conductas atípicas. Un total de 1,255 participantes completaron una encuesta en línea, que incluyó áreas sociodemográficas, fantasías sexuales, deseos y comportamientos específicos y variables psicológicas. Los participantes pudieron expresar intereses entre fantasías, deseos y comportamientos en cada actividad parafílica. La mayoría de las personas participantes tenían al menos un título universitario (78,2%), eran católicos (65%) y se identificaban como hispanos (86,3%). Los resultados mostraron que la mayoría no informaron actividades parafílicas sexuales. La actividad más reportada fue mirar pornografía, seguida por el parcialismo y el voyerismo. El análisis de correlaciones entre las fantasías sexuales y los comportamientos mostraron una correlación significativa entre el voyerismo con: exhibicionismo, froteurismo, ver a su pareja tener sexo con otra persona y ver pornografía. Estos resultados proporcionan una nueva perspectiva sobre los intereses parafílicos actuales en la población no clínica y deberían suscitar interés en estudios adicionales.