Alina West

Regulation and function of the two-pore-domain (K2P) potassium channel Trek-1 in alveolar epithelial cells

Hyperoxia can lead to a myriad of deleterious effects in the lung including epithelial damage and diffuse inflammation. The specific mechanisms by which hyperoxia promotes these pathological changes are not completely understood. Activation of ion channels has been proposed as one of the mechanisms required for cell activation and mediator secretion. The two-pore-domain K(+) channel (K2P) Trek-1 has recently been described in lung epithelial cells, but its function remains elusive. In this study we hypothesized that hyperoxia affects expression of Trek-1 in alveolar epithelial cells and that Trek-1 is involved in regulation of cell proliferation and cytokine secretion. We found gene expression of several K2P channels in mouse alveolar epithelial cells (MLE-12), and expression of Trek-1 was significantly downregulated in cultured cells and lungs of mice exposed to hyperoxia. Similarly, proliferation cell nuclear antigen (PCNA) and Cyclin D1 expression were downregulated by exposure to hyperoxia. We developed an MLE-12 cell line deficient in Trek-1 expression using shRNA and found that Trek-1 deficiency resulted in increased cell proliferation and upregulation of PCNA but not Cyclin D1. Furthermore, IL-6 and regulated on activation normal T-expressed and presumably secreted (RANTES) secretion was decreased in Trek-1-deficient cells, whereas release of monocyte chemoattractant protein-1 was increased. Release of KC/IL-8 was not affected by Trek-1 deficiency. Overall, deficiency of Trek-1 had a more pronounced effect on mediator secretion than exposure to hyperoxia. This is the first report suggesting that the K(+) channel Trek-1 could be involved in regulation of alveolar epithelial cell proliferation and cytokine secretion, but a direct association with hyperoxia-induced changes in Trek-1 levels remains elusive.

Regulation of inflammatory biomarkers by intravenous methylprednisolone in pediatric ARDS patients: Results from a double-blind, placebo-controlled randomized pilot trial.

OBJECTIVE A double-blind, randomized controlled trial showed that low-dose glucocorticoid therapy in pediatric ARDS patients is feasible and may improve both ventilation and oxygenation indices in these patients. However, the molecular mechanisms underlying potential changes in outcomes remain unclear. Based on these clinical findings, this study was designed to examine the effects of intravenous methylprednisolone on circulating inflammatory biomarkers in pediatric ARDS patients. DESIGN Double-blind, placebo-controlled randomized trial with blood collection on study entry and day 7. SETTING Tertiary care childrens hospital. PATIENTS Children (0-18years) with ARDS undergoing mechanical ventilation. INTERVENTIONS 35 children were randomized within 72h of mechanical ventilation. The glucocorticoid group received methylprednisolone 2mg/kg loading dose followed by 1mg/kg/day continuous infusion from days 1 to 7. Both groups were ventilated following the ARDSnet recommendations. WBC and differential cell counts, plasma cytokines and CRP levels, and coagulation parameters were analyzed on days 0 and 7. RESULTS At study entry, the placebo group had higher IL-15 and basophil levels. On day 7, in comparison to study entry, the placebo group had lower IL-1α, IFN-γ and IL-10 levels. The glucocorticoid group had lower INF-α, IL-6, IL-10, MCP-1, G-CSF and GM-CSF levels, and higher IL-17α levels on day 7 in comparison to study entry. Total and differential cell counts remained unchanged within the placebo group between days 0 and 7, whereas in the glucocorticoid group total WBC and platelets counts were increased on day 7. Pearsons correlation studies within the placebo and glucocorticoid groups revealed positive and negative correlations between cytokine levels, cell counts, coagulation parameters and relevant clinical parameters of disease severity identified in our previous study. Multiple regression models identified several cytokines as predictors for alterations in clinical parameters of disease severity. CONCLUSION This pilot study shows the feasibility of simultaneously measuring multiple inflammatory cytokines, cell counts and coagulation parameters in pediatric ARDS patients. We report statistical models that may be useful for future, larger trials to predict ARDS severity and outcomes.

Clinical risk factors for central line-associated venous thrombosis in children.

Background Identifying risk factors related to central venous line (CVL) placement could potentially minimize central line-associated venous thrombosis (CLAVT). We sought to identify the clinical factors associated with CLAVT in children. Methods Over a 3-year period, 3733 CVLs were placed at a tertiary-care children’s hospital. Data were extracted from the electronic medical records of patients with clinical signs and symptoms of venous thromboembolism, diagnosed using Doppler ultrasonography and/or echocardiography. Statistical analyses examined differences in CLAVT occurrence between groups based on patient and CVL characteristics (type, brand, placement site, and hospital unit). Results Femoral CVL placement was associated with greater risk for developing CLAVT (OR 11.1, 95% CI 3.9–31.6, p < 0.0001). CVLs placed in the NICU were also associated with increased CLAVT occurrence (OR 5.3, 95% CI 2.1–13.2, p = 0.0003). CVL brand was also significantly associated with risk of CLAVT events. Conclusion Retrospective analyses identified femoral CVL placement and catheter type as independent risk factors for CLAVT, suggesting increased risks due to mechanical reasons. Placement of CVLs in the NICU also led to an increased risk of CLAVT, suggesting that small infants are at increased risk of thrombotic events. Alternative strategies for CVL placement, thromboprophylaxis, and earlier diagnosis may be important for reducing CLAVT events.

Transpyloric Feeding Tube Placement Using Electromagnetic Placement Device in Children

Background: Transpyloric feeding tubes (TPT) are often recommended in critically ill children. Blind tube placement, however, can be difficult, be time-consuming, and incur multiple radiation exposures. An electromagnetic device (EMD) is available for confirmation of successful placement of TPTs. We conducted a retrospective cohort study to evaluate the efficacy of an EMD for TPT placement in children and determine its impact on placement success, radiation exposure, confirmation time, and cost for tube placement compared with traditional blind TPT placement. Materials and Methods: Retrospective data were collected in patients receiving a TPT before (pre-EMD group) and after implementation of an EMD (EMD group). Results: Need for radiographic exposure decreased significantly in the EMD group (n = 40) compared with the pre-EMD group (n = 38) (0.6 vs 1.6 x-rays, P < .001). TPTs were placed and confirmed without abdominal x-ray in 21 of 40 patients in the EMD group. There were no serious adverse events such as misplacement into the lung or pneumothorax or perforation injury of the stomach. Successful tube confirmation took a significantly shorter time in the EMD group than in the pre-EMD group (1.45 vs 4.59 hours, P < .0001). There was an estimated cost savings of

Single Center Outcomes of Status Epilepticus at a Paediatric Intensive Care Unit.

245.10 per placement associated with decreased x-ray and fluoroscopy. Conclusion: The use of an EMD in children significantly decreased radiation exposure and confirmation time while maintaining TPT placement success. The use of an EMD can potentially offer large cost savings. Elimination of abdominal x-ray with EMD during TPT placement was achieved without any serious complications in approximately half of the children.