Pathophysiology of congenital diaphragmatic hernia. III: Exogenous surfactant therapy for the high-risk neonate with CDH.

Exogenous surfactant therapy (EST) in surfactant-deficient premature infants has been shown to improve lung compliance, decrease morbidity, and improve survival. Reports have demonstrated that newborns with congenital diaphragmatic hernia (CDH) have lung compliance, pressure-volume curves, and hyaline membrane formation resembling those changes seen in surfactant deficient premature newborns. We hypothesize that EST may also benefit infants with CDH.

Interstitial pulmonary macrophages produce platelet-derived growth factor that stimulates rat lung fibroblast proliferation in vitro.

Alveolar macrophages from humans and several animal species produce factors in vitro that modulate fibroblast growth and have been proposed as mediators of interstitial pulmonary fibrosis. Pulmonary interstitial macrophages (IMs) have not been studied previously in this regard. Pulmonary IMs were isolated from prelavaged rat lungs by enzymatic digestion of tissue and subsequent differential adherence of cells to culture dishes.

Deposition, clearance, and translocation of chrysotile asbestos from peripheral and central regions of the rat lung.

We investigated the pulmonary deposition, clearance, and translocation of chrysotile asbestos in the context of our previously developed model of asbestosis in the rat. Adult male rats were exposed for 3 hr to an aerosol of chrysotile asbestos. Subgroups were sacrificed up to 29 days postexposure and the lungs of the animals fixed.

Studies on the incorporation of lanthanides in dental hard tissues.

Rare earth elements (lanthanides)--known from chrystal-chemistry for the rehardening effect on apatites--have been tested previously for the possibility of their incorporation in dental enamel. From the non-toxic lanthanides cerium was incorporated under in vitro conditions in human dental enamel. In the present study, the incorporation of lanthanum (La), europium (Eu), samarium (Sa), ytterbium (Yb) and neodymium (Nd) in human permanent enamel, dentine and deciduous enamel has been investigated by neutron activation analysis.

Rotational remodeling of malrotated femoral fractures: a model in the rabbit.

It is estimated that 20-40% of femoral fractures in children heal in malrotation, yet few patients later complain. To determine if malrotation corrects spontaneously, midshaft osteotomies were made in femurs of 16 rabbits aged 8 weeks and the distal fragments were internally rotated 45 degrees, where they were held with external fixators. The animals were killed between week 0 and week 17.

Markers for occult liver injury in cases of physical abuse in children.

Children suffering physical abuse are at risk for abdominal trauma. When the abdominal trauma is not evident clinically and remains occult, the child's condition can rapidly deteriorate before the diagnosis is made, and delay may occur in the activation of child protective services. The use of markers for abdominal trauma in the evaluation of cases of child physical abuse was examined.

Needle aspiration of neck abscesses in children.

Needle aspiration of neck abscesses with CT-scan guidance was studied in 17 children with 18 abscesses from 1986 to 1991. Clinical and radiologic findings were analyzed according to treatment outcome. A majority of abscesses (55.

Isolated intrathoracic spleen presenting as an enlarging chest mass. CT and MRI findings.

We present the first reported case of an isolated intrathoracic spleen. This presented as an enlarging chest mass in a 6-month-old infant. The lack of symptoms and absence of herniated bowel caused an interesting diagnostic problem which was elegantly solved by a combination of imaging modalities.

Differential proliferation of rat lung fibroblasts induced by the platelet-derived growth factor-AA, -AB, and -BB isoforms secreted by rat alveolar macrophages.

Platelet-derived growth factor (PDGF)-like molecules secreted by alveolar macrophages have been postulated to be mediators of lung fibrogenesis since these cytokines stimulate the proliferation and chemotaxis of lung fibroblasts. We are studying the biology and biochemistry of rat macrophage-derived PDGF and have identified for the first time the specific isoforms of PDGF (-AA, -AB, and -BB) that these macrophages secreted in vitro following activation with either chrysotile asbestos or carbonyl iron spheres. Subsequently, the proliferative response of rat lung fibroblasts (RLF) to the different PDGF isoforms was established.

First-pass entry of nonionic contrast agent into the myocardial extravascular space. Effects on radiographic estimates of transit time and blood volume.

Background: Almost all x-ray-based techniques intended to assess regional myocardial perfusion from myocardial concentration-time curves following the administration of soluble contrast agents assume that these agents behave as intravascular indicators and can therefore provide measurements of intravascular transit time and intramyocardial blood volume.

Methods And Results: We tested this assumption by comparing a conventional nonionic contrast agent (ioversol) to a particulate emulsion (ethiodol) that remained in the vascular space in closed-chest dogs during pharmacological vasodilation. Using fast computed tomography (CT), pairs of myocardial CT intensity-time curves were obtained following sequential bolus aortic administration of the two contrast agents.

Inorganic particles induce secretion of a macrophage homologue of platelet-derived growth factor in a density-and time-dependent manner in vitro.

The inhalation of inorganic dust can lead to the development of interstitial pulmonary fibrosis, characterized by the accumulation of fibroblasts and connective tissue matrix in the lung interstitium. The fibrosis causes alterations in the architecture of the lung parenchyma, resulting in abnormal gas exchange and hypoxemia. In a rat model of asbestos exposure, inhaled fibers are deposited on alveolar duct bifurcations, followed by an accumulation of alveolar macrophages at the sites of dust deposition.

Lung cell toxicity experimentally induced by a mixed dust from Mexicali, Baja California, Mexico.

Lung disease caused by nonoccupational exposures to inorganic particles from the soil has been reported in several areas of the world. We tested the toxic potential of dust samples from a Mexican city (Mexicali) that is frequently affected by dust storms and is geographically related to the area of San Diego, CA, where constituents of the soil have been reported to be fibrogenic. We found that samples of Mexicali dust are a mixture of approximately 75% potassium aluminum silicates (illite) and approximately 20% silica.

John Caffey Award paper. Avascular necrosis: early MR imaging and histologic findings in a canine model.

To examine the early MR and histologic changes of avascular necrosis, we surgically devascularized the distal femur of adult beagle dogs and performed short TR/short TE MR imaging and histologic examinations. MR showed increasing areas of low signal, and histologic examination showed changes of fat necrosis, inflammatory infiltrate, and fibrocytic and bony repair. These processes were divided into four stages.

New perspectives in CT and MR imaging.

Neuroimaging is a rapidly changing part of the care of children with central nervous system neoplasms. MR scanning, now a routine part of patient care, continues to advance, with new capabilities continuously developing. CT scanning, although often eclipsed by MRI, remains an essential imaging modality.

Receptors for transforming growth factor-beta (TGF-beta) on rat lung fibroblasts have higher affinity for TGF-beta 1 than for TGF-beta 2.

Most cell types have receptors for transforming growth factor-beta (TGF-beta) and respond similarly to TGF-beta 1 and TGF-beta 2. We have demonstrated the presence of a single class of high-affinity receptors (approximately 10,000 sites/cell) for TGF-beta 1 (Kd = 23 pM) and TGF-beta 2 (Kd = 41 pM) on early-passage rat lung fibroblasts (RLF). Incubation with unlabeled TGF-beta 1 and TGF-beta 2 resulted in concentration-dependent inhibition of binding of 15 pM [125I]TGF-beta 1 (ED50, 20 and 28 pM, respectively) and [125I]TGF-beta 2 (ED50, 36 and 56 pM, respectively).

Cellular and molecular basis of the asbestos-related diseases.

Asbestosis is an inflammatory and fibrotic process of the alveolar structures mediated, at least in part, by cytokines released by "activated" alveolar macrophages. The process of phagocytosis and "activation" of alveolar macrophages is poorly understood. Are all macrophages activated or only subpopulations? Which cytokines are up-regulated? How does the local milieu modulate profibrotic and antifibrotic mediators? Is protein release accompanied by up-regulation of gene transcription? Is there an ordered sequence of cytokine activity? What roles do neutrophils and lymphocytes play? How can disease progression best be quantified absent further exposure? Answers to these questions are important to direct rational strategies at interdicting the fibrotic process.

Airway evaluation in children with use of ultrafast CT: pitfalls and recommendations.

Ultrafast computed tomographic (CT) evaluation of the airway can be performed with either 50-msec low-resolution images (cine CT) or 100-msec high-resolution images (high-resolution CT). To determine the best imaging strategy for ultrafast CT of the pediatric airway, the authors prospectively compared ultrafast CT and endoscopy in 20 children. Both studies were performed in 11 patients; cine CT alone was performed in six and high-resolution CT alone in three.

Changes in lipid ordering of model phospholipid membranes treated with chrysotile and crocidolite asbestos.

A variety of inorganic particles bind to cell membranes and cause alterations in phagocytosis, migration, and metabolism leading to eventual cell death. The mechanism which mediate these events at the complex membrane level are not known. In attempting to define the mechanisms of asbestos-induced membrane changes, we have prepared small unilamellar vesicles (SUV) of dipalmitoyl phosphatidylcholine as a simplified model of the cell membrane.

Co-culture of primary pulmonary cells to model alveolar injury and translocation of proteins.

Primary rat alveolar type II cells and early passage rat lung fibroblasts were co-cultured on opposite sides of a collagen-coated polycarbonate filter. This is an approach to "model", in part, an alveolar wall to study mechanisms of cytotoxicity and translocation of bioactive materials from the alveolar space to the lung interstitium. Type II cells were recovered from adult rat (Fischer 344) lungs by enzyme digestion and "panning".

Rat alveolar macrophage-derived platelet-derived growth factor is chemotactic for rat lung fibroblasts.

Alveolar macrophages and their products are thought to be important mediators of the inflammatory lesions and consequent interstitial fibrosis caused by inhalation of inorganic particles. Identification of a homolog of platelet-derived growth factor (PDGF) produced by rat alveolar macrophages that were stimulated with carbonyl iron particles and asbestos fibers motivated our studies on the biologic activity of this potent cytokine. Macrophage-derived PDGF (MD-PDGF) competes for specific membrane receptors on rat lung fibroblasts, initiating DNA synthesis and cell replication.