David H. Ingbar

Repopulation of a human alveolar matrix by adult rat type II pneumocytes in vitro: A novel system for type II pneumocyte culture

This paper describes the preparation of lung acellular alveolar matrix fragments and culture of rat type II pneumocytes directly on the alveolar epithelial basement membrane, thereby permitting study of the effect of lung basement membrane on the morphology and function of type II cells. Collagen types I, III, IV and V, laminin and fibronectin were located by immunofluorescence in the lung matrix with the same patterns as those described for the normal human lung. Transmission electron microscopy (TEM) of the fragments revealed intact epithelial and endothelial basement membranes. The matrix maintained the normal three-dimensional alveolar architecture. Glycosaminoglycans were still present by Alcian Blue staining. Isolated adult rat type II pneumocytes cultured on 150 micron thick fragments of acellular human alveolar extracellular matrix undergo gradual cytoplasmic flattening, with loss of lamellar bodies, mitochondria, and surface microvilli. These changes are similar to the in vivo differentiation of type II pneumocytes into type I pneumocytes. The type II pneumocyte behaviour on the lung epithelial basement membrane contrasted sharply with that of the same cell type cultured on a human amnionic basement membrane. On the latter surface the cells retained their cuboidal shape, lamellar bodies and surface microvilli for up to 8 days. These observations suggest that the basement membranes from different organ systems exert differing influences on the morphology and function of type II pneumocytes and that the alveolar and amnionic basement membranes may have differing three-dimensional organizations. The technique of direct culture of type II cells on the lung basement membrane provides a useful tool for studying the modulating effect of the basement membrane on alveolar epithelial cells.

Polarized distribution of Na+,K+-ATPase in giant cells elicited in vivo and in vitro.

Giant cell formation was analyzed to determine whether it results in the high level of Na+,K+-ATPase expression that characterizes multinucleated cells such as osteoclasts. Giant cells and fusing alveolar macrophages were subjected to morphological, immunological, and biochemical studies. Both subunits of the Na+,K+-ATPase were found to be present on the plasma membrane of giant cells. Their localization was restricted to the non-adherent domain of the cell surface. Dynamic studies of giant cell differentiation demonstrated that on culture and/or multinucleation, an increase in sodium pump alpha-subunit synthesis occurred and led to a high level of expression of Na pumps. Conversely, the adherent plasma membrane of giant cells was enriched in a lysosomal membrane antigen. This study demonstrates that culture and/or multinucleation induces a significant increase in the expression of sodium pumps. The polarized distribution of these pumps and of a lysosomal component suggests that fusing macrophages undergo biochemical and morphological alterations which prepare them for a new and specialized function in chronic inflammatory reactions. Giant cells may offer a suitable model system to study the differentiation of other related multinucleated cells, such as osteoclasts.

Massive Hemoptysis: Pathogenesis and Management

Massive hemoptysis is a life-threatening complication of many pulmonary disorders, and it occurs most com monly in association with longstanding inactive tuber culosis, bronchiectasis, lung abscess, bronchogenic car cinoma, and fungal disease. It is generally a neovascular change or local erosive effect of chronic pulmonary dis ease and may originate from either bronchial or pulmo nary circulation. Recurrent bleeding is unpredictable; therefore, diagnostic and therapeutic intervention must be undertaken with urgency. The immediate priorities must be protection of the airway to the nonbleeding lung and localization of the site of hemorrhage prefera bly by bronchoscopy, which has a high yield when per formed during active hemorrhage. Immediate control of bleeding may be obtained by local tamponade with a balloon-tipped Fogarty catheter, use of a double-lumen endotracheal tube, or angiographically guided emboliza tion. Surgical resection is the preferred definitive treat ment for those who meet operative criteria; those who lack adequate pulmonary reserve are candidates for em bolization of sites with persistent bleeding. The high mortality of conservatively treated massive hemoptysis and the current inability to predict which patients will have fatal hemorrhage mandate rapid assessment and intervention.

A universal precautions monitoring system adaptable to any health care department

The Occupational Safety and Health Administration has proposed monitoring employee compliance with universal precautions, as recommended by the Centers for Disease Control. Our respiratory care department, following a four-step system development plan, has developed and implemented a universal precautions monitoring system that is easy to adapt to any health care department. The results from monitoring can be used for educational planning, quality assurance purposes, and employee performance reviews.

Fatal infective endocarditis in a young adult with persistent truncus arteriosus and a bicuspid truncal valve

Abstract Persistent truncus arteriosus (TA) is usually fatal in infancy or early childhood. Almost all survivors beyond early childhood have severe elevation in pulmonary vascular resistance or have undergone a corrective surgical procedure.1 Although infective endocarditis is associated with a variety of congenital cardiac abnormalities, it has rarely been reported with TA and has not been reported as a cause of death in any such patient.2 Herein, we report a patient with TA who survived to age 19 years and died from infective endocarditis on a bicuspid truncal valve.