The signal transduction events that follow the binding of lipopolysaccharide (LPS) to the macrophage cell surface are not well defined. In the current studies LPS was found to induce alterations in phosphorylation of monocyte proteins on tyrosine. Herbimycin A and genistein, inhibitors of tyrosine kinases, markedly attenuated LPS-induced tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) protein and mRNA production. Reciprocally, the tyrosine phosphatase inhibitor sodium orthovanadate enhanced LPS-induced production of TNF-alpha. LPS induced a concentration-dependent increase in tyrosine phosphorylation of several proteins, which paralleled and preceded the onset of LPS-induced TNF-alpha production. LPS stimulation had different but reproducible effects on three members of the src family of tyrosine kinases. Both Hck and Lyn kinase activity increased before the onset of TNF-alpha production, consistent with their participation in the observed LPS-induced tyrosine phosphoprotein accumulation. In contrast, Yes kinase activity was not affected. These observations were made at concentrations of LPS that required serum rich in LPS-binding protein and the monocyte surface antigen CD14 for TNF-alpha production. These data indicate that tyrosine kinases and phosphatases are involved in the signal transduction cascade by which LPS induces production of TNF-alpha and IL-6 by human monocytes, and suggest that Lyn and Hck are candidate participants in this process.

TWAR, the only known serovar of Chlamydia pneumoniae, is a newly described bacterium that has been identified as a cause of both epidemics and endemic cases of pneumonia. The role of TWAR infection in patients with chronic obstructive pulmonary disease (COPD) is not known. We conducted a prospective study to establish whether TWAR infection is a common cause of acute exacerbations of COPD. We studied two groups of patients: 44 patients admitted to the hospital with acute exacerbations of COPD, and 65 stable clinic patients with COPD. We found that evidence of acute TWAR infection was infrequent in patients with exacerbations (5%). In contrast, the majority of patients from both groups had serologic evidence of previous TWAR infection (77%). This was not significantly greater than the prevalence found in a small group of patients of similar age and sex without lung disease from the same institution (73%). TWAR was not isolated from the oropharyngeal specimens obtained from 97 subjects, suggesting that it does not colonize the respiratory tract of patients with COPD. This study shows that at the time of low incidence in the community, acute TWAR infection is uncommon in patients with acute exacerbations of COPD. The majority of patients with COPD have, however, been infected with TWAR in the past. The clinical manifestations of these infections are not known and should be the focus of further studies.

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Extracorporeal membrane oxygenation (ECMO) is used for cardiopulmonary dysfunction. Hepatopulmonary syndrome (HPS) occurs in the setting of liver failure and may cause hypoxemia. Previous reports have described the use of ECMO for HPS after liver transplant. Our patient is a 19-month-old female with biliary atresia, an interrupted inferior vena cava, and HPS on 8 liters per minute of high-flow oxygen. Following liver transplantation, her postoperative course was complicated by severe hypoxemia requiring ECMO. Due to her interrupted inferior vena cava, our standard bi-caval cannula could not be used. Hence, a 16-French double lumen venovenous right internal jugular to right atrial cannula was used to provide extracorporeal life support. She was decannulated after 17 days, remained intubated for 2 days, and weaned to room air over the next 3 weeks. This is the third pediatric liver transplant patient supported with ECMO identified in the literature, and the youngest and smallest of those reported. This approach to cannulation is unique because of the use of a double lumen venovenous cannula for HPS in a child, selected due to complex anatomy. Posttransplant ECMO may provide pediatric patients with HPS and posttransplant hypoxemia a period of support for their pulmonary remodeling and recovery from HPS.