The effects of testing in shifts on a clinical in-course computerized exam

PROBLEM

Testing a large medical class over two days with a single-form computer-based test has generated questions related to test security and the influence of unequal test preparation times afforded by the testing method.

METHODS

An analysis of variance (anova) design was used to compare the scores for the two days for each of the three tests. In addition, a within-student match-paired t-test of standard score differences was used to examine the relative standing of students across tests administered on different days.

RESULTS

Both the anova and the match-paired t-test failed to detect a difference between first and second day testing.

CONCLUSION

This research suggests that using a single test form with shift-based computerised assessments, spread over as many as two days, does not seriously compromise the integrity of the results. Since creating multiple unique-item forms is often not possible, shift-based testing with a single test form appears to be a fair method of accommodating a large number of students.

Ceramide regulates lipopolysaccharide-induced phosphatidylinositol 3-kinase and Akt activity in human alveolar macrophages

The phosphatidylinositol (PI) 3-kinase pathway is an important regulator of cell survival. In human alveolar macrophages, we found that LPS activates PI 3-kinase and its downstream effector, Akt. LPS exposure of alveolar macrophages also results in the generation of ceramide. Because ceramide exposure induces apoptosis in other cell types and the PI 3-kinase pathway is known to inhibit apoptosis, we determined the relationship between LPS-induced ceramide and PI 3-kinase activation in alveolar macrophages. We found that ceramide exposure activated PI 3-kinase and Akt. When we blocked LPS-induced ceramide with the inhibitor D609, we blocked LPS-induced PI 3-kinase and Akt activation. Evaluating cell survival after ceramide or LPS exposure, we found that blocking PI 3-kinase induced a significant increase in cell death. Because these effects of PI 3-kinase inhibition were more pronounced in ceramide- vs LPS-treated alveolar macrophages, we also evaluated NF-kappaB, which has also been linked to cell survival. We found that LPS, to a greater degree than ceramide, induced NF-kappaB translocation to the nucleus. As a composite, these studies suggest that the effects of ceramide exposure in alveolar macrophages may be very different from the effects described for other cell types. We believe that LPS induction of ceramide results in PI 3-kinase activation and represents a novel effector mechanism that promotes survival of human alveolar macrophages in the setting of pulmonary sepsis.

GM-CSF increases AP-1 DNA binding and Ref-1 amounts in human alveolar macrophages

Alveolar macrophages have been implicated in the pathogenesis of a number of acute and chronic lung disorders. A characteristic feature of many of the chronic lung diseases is that the types of macrophages in the lung change, and in most instances, the cells resemble monocyte-like cells. We have previously shown that normal human alveolar macrophages have a decreased capacity to express protein kinase C (PKC)-induced DNA binding activity of the transcription factor activator protein (AP)-1 compared with monocytes. This decrease in AP-1 DNA binding appears to be due to a defect in redox regulation of AP-1 proteins via a decrease in the redox active protein Ref-1. The hypothesis for this study is that there are factors generated during the development of chronic lung disease that increase AP-1 DNA binding activity and Ref-1 production in human alveolar macrophages. We have focused specifically on granulocyte-macrophage colony-stimulating factor (GM-CSF) as a prototype mediator that can be released by alveolar macrophages and is related to the fibrotic process in the lung. We found that after a 24-h incubation with GM-CSF, AP-1 DNA binding was significantly increased in both unstimulated, interleukin (IL)-13, and phorbol myristate acetate (PMA)-stimulated alveolar macrophages and that there was a corresponding increase in Ref-1 protein by Western blot analysis in the PMA-stimulated group. This suggests that disease-related cytokines such as GM-CSF and IL-13 may modulate AP-1 DNA binding activity in alveolar macrophages.

Asthma patient education: current utilization in pulmonary training programs

The national guidelines for the diagnosis and management of asthma published in April of 1997 emphasized patient education in asthma management. It is unclear how often patient education is included in asthma management clinics. We sought to determine how often education programs are available by surveying teaching hospitals with training programs in pulmonary and critical care medicine. Using this survey, we also determined the reason programs are not offered and whether computer resources are routinely available to utilize computer-delivered patient educational materials. We sent mail questionnaires to 163 training programs in the United States. We had a response rate of 72% (117 of 163). Of the 117 programs responding, 75 (64%) reported having a formal asthma patient education program. Most (72%) were in university teaching hospitals. A majority of respondents (84%) believed that compensation for their efforts was inadequate, and those hospitals with no formal asthma education program reported that financial cost and time requirements were the primary reasons for not having such a program. Despite the fact that many programs did not have a patient education component, 96% (72 of 75) of respondents with an educational program viewed patient education as an effective patient self-management tool. Of all programs surveyed, 85% reported they would use a high-quality computer-based asthma education program if one was available. Implementation of such a program is feasible, with 69% of programs surveyed having a personal computer in their clinic and 60% having Internet access. We conclude that most training directors believe that patient asthma education is important and effective; however, cost and time issues remain barriers to its implementation. Computer-based educational programs delivered over the Internet are feasible, could address some of these limitations, and are acceptable to most programs.

Lipopolysaccharide activates Akt in human alveolar macrophages resulting in nuclear accumulation and transcriptional activity of beta-catenin

Exposure of human alveolar macrophages to bacterial LPS results in activation of a number of signal transduction pathways. An early event after the alveolar macrophage comes in contact with LPS is activation of the phosphatidylinositol 3 kinase (PI 3-kinase). This study evaluates the downstream effects of that activation. We observed that LPS exposure results in phosphorylation of Akt (serine 473). We found this using both phosphorylation-specific Abs and also by in vivo phosphorylation with (32)P-loaded cells. AKT activation resulted in the phosphorylation-dependent inactivation of glycogen synthase kinase (GSK-3) (serine 21/9). We found that both of these events were linked to PI 3-kinase because the PI 3-kinase inhibitors, wortmannin and LY294002, inhibited LPS-induced phosphorylation of both AKT and GSK-3. Inactivation of GSK-3 has been shown to reduce the ubiquitination of beta-catenin, resulting in nuclear accumulation and transcriptional activity of beta-catenin. Consistent with this, we found that LPS caused an increase in the amounts of PI 3-kinase-dependent nuclear beta-catenin in human alveolar macrophages and expression of genes that require nuclear beta-catenin for their activation. This is the first demonstration that LPS exposure activates AKT, inactivates GSK-3, and causes accumulation and transcriptional activity of beta-catenin in the nucleus of any cell, including alveolar macrophages.

Protein kinase C zeta plays a central role in activation of the p42/44 mitogen-activated protein kinase by endotoxin in alveolar macrophages

Human alveolar macrophages respond to endotoxin (LPS) by activation of a number of mitogen-activated protein kinase pathways, including the p42/44 (extracellular signal-related kinase (ERK)) kinase pathway. In this study, we evaluated the role of the atypical protein kinase C (PKC) isoform, PKC zeta, in LPS-induced activation of the ERK kinase pathway. Kinase activity assays showed that LPS activates PKC zeta, mitogen-activated protein/ERK kinase (MEK, the upstream activator of ERK), and ERK. LPS did not activate Raf-1, the classic activator of MEK. Pseudosubstrate-specific peptides with attached myristic acid are cell permeable and can be used to block the activity of specific PKC isoforms in vivo. We found that a peptide specific for PKC zeta partially blocked activation of both MEK and ERK by LPS. We also found that this peptide blocked in vivo phosphorylation of MEK after LPS treatment. In addition, we found that LPS caused PKC zeta to bind to MEK in vivo. These observations suggest that MEK is an LPS-directed target of PKC zeta. PKC zeta has been shown in other systems to be phosphorylated by phosphatidylinositol (PI) 3-kinase-dependent kinase. We found that LPS activates PI 3-kinase and causes the formation of a PKC zeta/PI 3-kinase-dependent kinase complex. These data implicate the PI 3-kinase pathway as an integral part of the LPS-induced PKC zeta activation. Taken as a whole, these studies suggest that LPS activates ERK kinase, in part, through activation of an atypical PKC isoform, PKC zeta.

Evaluation of an Internet-based decision-support system for applying the ATS/CDC guidelines for tuberculosis preventive therapy

Preventive therapy for patients infected with tuberculosis (TB) remains an important component of TB control. To guide physicians in applying preventive therapy, the American Thoracic Society and Centers for Disease Control (ATS/CDC) developed guidelines based on PPD reactivity and on pretest probability of infection. The guidelines have become complex, and many clinicians find them challenging to apply. The authors developed a computerized decision-support system to assist clinicians in applying the ATS/CDC guidelines. This tool, published on the World Wide Web using hypertext markup language, delivers patient-specific recommendations based on physician-delivered patient-specific information. Four local TB experts derived eight TB infection scenarios and validated the web-based tool, which was tested for effectiveness using general internal medicine residents, randomly divided into two groups. Group A (n = 12) used the web-based tool and group B (n = 17) used pre-existing understanding of the guidelines and/or written resources to determine the need for preventive therapy in the case scenarios. Group A correctly used therapy in 92/96 possible cases (95.8%), group B in only 77/136 (56.6%) (p < 0.001). Group A required a mean of three mouse-clicks and 1.5 minutes per scenario to reach their choices, and they rated the web-based tool both intuitive and effective. These data demonstrate that a computer-based decision-support system for applying TB treatment guidelines can be delivered over the Internet and provide an efficient and effective resource for clinicians.

Asthma guidelines: an assessment of physician understanding and practice

In 1997 the NHLBI updated guidelines for the diagnosis and management of asthma. We hypothesized that not all components of the updated guidelines are well understood by the physicians who care for asthmatics. To develop appropriate educational interventions that address areas of physician misunderstanding, it is important to identify these components. Based upon NHLBI guidelines, we developed a multiple-choice test of asthma knowledge that was distributed to physicians at the University of Iowa; 108 physicians completed the test, including 20 asthma specialists, 11 asthma specialty fellows, 11 General Medicine faculty, five Family Medicine faculty, 51 Internal Medicine residents, and five Family Medicine residents. The mean correct total score for all physicians was 60 +/- 2% (mean +/- SEM). Asthma specialists scored higher in total score and in pharmacology and prevention. However, no group performed well on estimating disease severity. We further identified deficits in the use of spirometry and anti-inflammatory agents in caring for asthmatic patients. Thus, deficits exist in physician understanding and implementation of the NHLBI guidelines for the diagnosis and management of asthma. By identifying specific areas of misunderstanding, we can design better educational interventions. Clearly, educational programs should emphasize new models for estimating chronic disease severity.

Realizing the promise: delivering pulmonary continuing medical education over the Internet

STUDY OBJECTIVES

Continuing medical education (CME) is meant to bridge the gap between new scientific observations and clinical practice. However, traditional CME has not been effective at altering the behaviors of physicians. One reason for this failure of traditional CME programs may be their inflexibility. In traditional CME, the clinician does not choose the topic, the pace of the program, or the place of learning, and the CME material cannot be easily delivered to the point of care where the clinician needs the information. Computers and computer networks have the potential to accomplish these goals. CME has begun to appear on the Internet; however, there have been few evaluations of its usefulness, acceptance, and effectiveness. Over the last 18 months, we have developed three on-line pulmonary CME programs, and we have delivered them on the Virtual Hospital, the University of Iowa's digital health sciences library on the Internet. We report our initial experience with this CME material.

DESIGN

We measured the frequency with which the Internet-delivered CME is accessed by monitoring page accessions and by using a log file analysis program (Analog 1.2.3; University of Cambridge Statistical Laboratory; Cambridge, UK). In addition, we collected all completed CME examinations and evaluation forms submitted by registered users.

MEASUREMENTS AND RESULTS

We have found that the frequency with which the Internet-delivered CME is accessed has continued to increase with time (2.3-fold increase over 18 months), that evaluations of technical and content issues are strongly favorable, and that some clinicians have been willing to pay to receive CME through the medium of the Internet.

CONCLUSIONS

We feel that with adequate peer review and quality control, physicians will use the Internet-delivered CME. However, several obstacles to wide use remain. These obstacles include issues regarding training in using the Internet for physicians, reluctance of physicians to participate in on-line commerce, and the current unavailability of CME to be delivered in small-grained quantities to the point of care. As these issues are addressed, we feel that on-line CME will represent an increasingly important CME medium for clinicians.

Asbestos-induced lung epithelial permeability: potential role of nonoxidant pathways

Asbestos fibers are an important cause of lung fibrosis; however, the biological mechanisms are incompletely understood. The lung epithelium serves an important barrier function in the lung, and disrupting the epithelial barrier can contribute to lung fibrosis. Lung epithelial permeability is increased in patients with asbestosis, and asbestos fibers increase permeability across cultured human lung epithelium. However, the mechanism of this increased permeability is not known. Many of the biological effects of asbestos are postulated to be due to its ability to generate oxidants, and oxidants are known to increase epithelial permeability. However, we previously reported that altering the iron content of asbestos (important in oxidant generation) had no effect on its ability to increase permeability. For that reason, we undertook these studies to determine whether asbestos increases epithelial permeability through nonoxidant pathways. Both extracellular (H2O2) and intracellular (menadione) oxidants increase paracellular permeability across human lung epithelial monolayers. Extracellular catalase but not superoxide dismutase prevented increased permeability after both oxidant exposures. However, catalase offered no protection from asbestos-induced permeability. We next depleted the cells of glutathione or catalase to determine whether depleting normal cellular antioxidants would increase the sensitivity to asbestos. Permeability was the same in control cells and in cells depleted of these antioxidants. In addition to generating oxidants, asbestos also activates signal transduction pathways. Blocking protein kinase C activation did not prevent asbestos-induced permeability; however, blocking tyrosine kinase with tyrophostin A25 did prevent asbestos-induced permeability, and blocking tyrosine phosphatase with sodium vanadate enhanced the effect of asbestos. These data demonstrate that asbestos may increase epithelial permeability through nonoxidant pathways that involve tyrosine kinase activation. This model offers an important system for studying pathways involved in regulating lung epithelial permeability.

CD11b/CD18 mediates the neutrophil chemotactic activity of fibrin degradation product D domain

Coagulation and fibrinolysis universally accompany tissue injury and repair. The accumulation of regionally generated fibrin degradation products (FDP) may modify the local inflammatory response. We have found FDP to be potent neutrophil chemotaxins. We separated plasmin FDP by chromatofocusing and found chemotactic activity limited to fractions containing the fibrinogen D domain (D-D dimer and D monomer). The bioactivity of the D-D dimer did not require an intact cross link site as removal of this sequence with puff adder venom or hypocalcemic plasmic digestion did not decrease chemotaxis. Peptide inhibition studies confirmed that the chemotactic region did not involve terminal gamma chain sequences or alpha chain RGD motifs. The internal gamma chain peptide KYGWTVFQKRLDGSV (P1), known to bind CD11b/CD18, exhibited concentration dependent chemotactic activity. Similarly, monoclonal antibodies directed against CD11b/CD18 blocked PMN migration to FDP without similar inhibition of chemotaxis to IL-8 or LTB4. Thus, neutrophil chemotaxis to FDP is mediated by interactions between the fibrinogen D domain and CD11b/CD18.

Human neutrophil elastase abolishes interleukin-8 chemotactic activity

A large body of literature supports the role of interleukin-8 (IL-8) in inflammatory lung disease. Numerous factors induce the local synthesis and secretion of this potent chemokine leading to the recruitment and activation of polymorphonuclear leukocytes. However, little is currently known about the fate of IL-8 secreted at sites of inflammatory injury. We have found that incubation of recombinant human IL-8 with purified human neutrophil elastase (HNE) results in the loss of IL-8 chemotactic activity in a dose- and time-dependent fashion. This loss in bioactivity is accompanied by a similar loss of IL-8 immunoreactivity. Western blot analysis revealed that IL-8 chemotactic activity is lost by proteolysis of the parent molecule into undetectable small fragments. The terminal digestion of IL-8 was specific to HNE as no loss of bioactivity was observed with equimolar concentrations of the serine proteases urokinase, plasmin, thrombin, or cathepsin G. This effect on chemotactic activity is not limited to recombinant IL-8 because HNE also digested IL-8 secreted by human monocytes. HNE-mediated proteolysis offers a novel mechanism for down-regulating the inflammatory cascade initiated by IL-8.

The role of fibrin degradation products in neutrophil recruitment to the lung

Pulmonary epithelial injury leads to increased permeability and plasma exudation. Plasma rapidly forms an insoluble fibrin clot in the distal airspace because of the potent procoagulant activity expressed there. Because these airspaces also express potent fibrinolytic activity, digestion of fibrin results in high local concentrations of fibrin degradation products (FDP), which are biologically important molecules with numerous proinflammatory actions. Inflammatory lung injury is associated with neutrophil accumulation, and other matrix proteins affect inflammatory cell traffic. In this study we examined the potential role of FDP in neutrophil recruitment to the lung. Using a chemotaxis assay, we found that FDP are potent chemotactic proteins when neutrophils are prestimulated with lipopolysaccharide (LPS) or formylmethionylleucylphenylalanine (fMLP). Although FDP are high molecular weight proteins, we found that these potent chemoattractants induce polymorphonuclear leukocyte (PMN) migration across epithelial monolayers. The magnitude of response is dependent upon the monolayers' ability to form and maintain tight junctions. Human neutrophil elastase (HNE), another fibrinolytic enzyme released from neutrophils, digests fibrin into chemotactic peptides which are more potent on a weight basis than plasmin-generated FDP. Furthermore, HNE secondarily digests plasmin FDP, producing molecules which are more potent chemoattractants than native plasmin FDP. These observations suggest a potential mechanism whereby FDP may contribute to the neutrophil accumulation which characterizes many inflammatory lung diseases.

Effect of neutrophil mediators on epithelial permeability

Inflammatory lung disease is associated with increased epithelial permeability, but it is unclear how inflammatory cells alter epithelial permeability. Neutrophils have azurophilic granules containing elastase, cathepsin G, and defensins which are released at sites of inflammation. Experiments using whole animals and cultured cells suggest that neutrophil elastase contributes to increased epithelial permeability. Using Madin-Darby canine kidney epithelial (MDCK) monolayers, a well-described epithelial model, we asked whether neutrophil elastase directly affects epithelial permeability independent of cell death or cell detachment from the substratum. We measured permeability using 3H-mannitol. We found that neutrophil elastase increased epithelial permeability in a time- and concentration-dependent fashion. Increased permeability required prolonged (> or = 6 h) exposure to elastase, but was not associated with cytolytic injury or cell detachment. These findings are potentially relevant to the lung because we found a similar time- and concentration-dependent effect when we added elastase to cultured human bronchial epithelial cells. In MDCK cells, permeability increased without alterations in cell actin at the light microscopic level. Interestingly, elastase-induced permeability was both prevented and reversed by serum, but not by serum albumin. Complete reversal occurred if serum was added up to 16 h after adding elastase. Proteolytic activity is important in HNE-induced epithelial permeability because soy bean trypsin inhibitor completely blocks the effect and alpha 1 proteinase inhibitor (alpha 1 PI) partially blocks the effect. Charge interactions also appear to be important because the polyanions heparin and sulfated dextran completely blocked increased permeability following elastase but only partially blocked elastolytic activity in isotonic solutions.(ABSTRACT TRUNCATED AT 250 WORDS)

Predicting postoperative pulmonary function in patients undergoing lung resection

OBJECTIVE

Our aim was to determine the effect of lung resection on spirometric lung function and to evaluate the accuracy of simple calculation in predicting postoperative pulmonary function in patients undergoing lung resection.

DESIGN

We reviewed preoperative and postoperative pulmonary function test results on patients who were followed in the multidisciplinary lung cancer clinic between July 1991 and March 1994 and who underwent lung resection. The predicted postoperative FEV1 and FVC were calculated based on the number of segments resected and were compared with the actual postoperative FEV1 and FVC.

SETTING

This study was conducted at a university, tertiary referral hospital.

PATIENTS

All patients were evaluated at a multidisciplinary lung cancer clinic and underwent lung resection by one surgeon (L.A.L.).

MEASUREMENTS AND MAIN RESULTS

Sixty patients undergoing 62 pulmonary resections were reviewed. The predicted postoperative FEV1 and FVC were calculated using the following formula: predicted postoperative FEV1 (or FVC) = preoperative FEV1 (or FVC) x (1-(S x 0.0526)); where S = number of segments resected. The actual postoperative FEV1 and FVC correlated well with the predicted postoperative FEV1 and FVC for patients undergoing lobectomy (r = 0.867 and r = 0.832, respectively); however, the predicted postoperative FEV1 consistently underestimated the actual postoperative FEV1 by approximately 250 mL. For patients undergoing pneumonectomy, the actual postoperative FEV1 and FVC did not correlate as well with the predicted postoperative FEV1 and FVC (r = 0.677 and r = 0.741, respectively). Although there was considerable variability, the predicted postoperative FEV1 consistently underestimated the actual postoperative FEV1 by nearly 500 mL. Of the patients undergoing lobectomy, eight also received postoperative radiation therapy. When analyzed separately, patients receiving combined therapy lost an average of 5.47% of FEV1 per segment resected. This contrasts with a 2.84% per segment reduction in FEV1 for patients who did not receive radiation therapy.

CONCLUSIONS

This simple calculation of predicted postoperative FEV1 and FVC correlates well with the actual postoperative FEV1 and FVC in patients undergoing lobectomy. The predicted postoperative FEV1 consistently underestimated the actual postoperative FEV1 by approximately 250 mL. The postoperative FEV1 and FVC for patients undergoing pneumonectomy is not accurately predicted using this equation. The predicted postoperative FEV1 for patients undergoing pneumonectomy was underestimated by an average of 500 mL and by greater than 250 mL in 12 of our 13 patients. Thus, by adding 250 mL to the above calculation of predicted postoperative FEV1, we improve our ability to we identify a minimal postoperative FEV1 for patients undergoing pneumonectomy. Finally, combined modality treatment with surgery followed by radiation therapy may result in additive lung function loss.

Thermal stress induces epithelial permeability

The mechanisms by which heat injury results in multiorgan system failure are unknown, but the presence of endotoxemia and intestinal hemorrhage suggests that changes in gut epithelial permeability may be crucial to this process. To determine whether alterations in epithelial permeability occur at physiologically relevant temperatures, heat-induced changes on epithelial barrier integrity were studied using a high-resistance clone of Madin-Darby canine kidney epithelial cells. Transepithelial electrical conductance increased when monolayers were heated above 38.3 degrees C. Early changes in conductance were completely reversible with cooling. Increased conductance was due to increased paracellular permeability because heat also induced increased mannitol permeability across the monolayers. A conditioning heat stress (42 degrees C for 90 min) altered heat-induced permeability. When cell monolayers were exposed to this conditioning stress 48 h before measurement of conductance with increasing temperatures, the conductance increase did not occur until they were heated to 39.4 degrees C compared with 38.8 degrees C in naive control cells. This conditioning treatment also conferred thermotolerance as measured by cell survival after a lethal 45.0 degrees C heat stress. There was no difference in the temperature at which conductance increased between preheated and control cells 96 h after a preconditioning heat stress. The conditioning heat stress resulted in accumulation of heat-shock protein (HSP) 70 in cells at 48 h, but HSP 70 returned to control levels at 96 h. These studies demonstrate that small temperature elevations increase epithelial permeability and that prior heat stress which induces HSP 70 shifts the threshold temperature required to disrupt the epithelium.

Asbestos exposure increases paracellular transport of fibrin degradation products across human airway epithelium

The inflammatory response to asbestos fiber inhalation suggests that the distal respiratory epithelium is an important early target of asbestos-induced injury. We have previously found that asbestos exposure increases the fibrinolytic activity and mannitol permeability of human airway epithelial cell monolayers. Because fibrin degradation products (FDP) are potent inflammatory mediators, we asked whether asbestos fiber exposure would increase the transepithelial flux of FDP into the interstitial space. To stimulate the pericellular environment following fiber deposition, asbestos-exposed epithelial monolayers grown on permeable filters were covered with human plasma containing fluorescein isothiocyanate (FITC)-labeled human fibrinogen. After 24 h, nearly twice as much FITC-FDP appeared in the abluminal chamber of asbestos-exposed monolayers compared with unexposed controls. This did not result solely from increased degradation product production because asbestos-exposed epithelium was more permeable at all apical FDP concentrations. The proteins that crossed asbestos-exposed monolayers included biologically relevant high-molecular-weight FDP, as demonstrated by streptavidin blotting of biotin-labeled FDP. We also found that FDP flux was not vectorial, was not saturable, did not involve proteolytic processing of FDP, and did not require active transport. Thus asbestos exposure increases the paracellular flux of intact FDP across human airway epithelium. This represents a novel mechanism whereby fiber-induced epithelial dysfunction may initiate and sustain inflammation in the distal airspace.

Betamethasone activation of CTP:cholinephosphate cytidylyltransferase in vivo is lipid dependent

Glucocorticoids increase surfactant phosphatidylcholine synthesis, in part, by stimulating the rate regulatory enzyme CTP:cholinephosphate cytidylyltransferase. This enzyme exists in mammalian lung cytosol as an active lipoprotein form (H-form) and an inactive apoprotein (L-form) species. We administered betamethasone to pregnant rats to examine the mechanisms for glucocorticoid stimulation of cytidylyltransferase activity in fetal lung. The hormone stimulated cytosolic activity threefold, and this effect was nearly abolished after lipid extraction. The addition of lipid extracts isolated from betamethasone-treated cytosolic preparations to L-form species increased enzyme activity to a greater extent than lipid extracts from control lungs. Further, the glucocorticoid increased the proportion of H-form activity from 34 to 55% of the total activity in the fetal lung cytosol. These changes were associated with a marked decrease in the activity of the L-form species. Analysis of the lipid composition of the H-form revealed that betamethasone increased the content of lipid activators, including phosphatidylglycerol and fatty acids. These observations provide evidence that glucocorticoid stimulation of CTP:cholinephosphate cytidylyltransferase in vivo is mediated by a conversion of the inactive form (L-form) to the active species (H-form). These studies further emphasize the critical role of lung lipids in mediating the glucocorticoid activation of this enzyme.

Asbestos directly increases lung epithelial permeability

Asbestos causes the fibrotic lung disease asbestosis, but the biologic basis for this is unknown. Lung epithelial dysfunction including increased permeability is hypothesized to contribute to lung scarring in other forms of pulmonary fibrosis. Lung epithelial permeability is increased in both animals and humans exposed to asbestos. It is not known whether the increased epithelial permeability results from direct effects of asbestos or occurs as a result of the inflammatory reaction to asbestos fibers. To address this question we used a cultured human lung epithelial model, and we measured the direct effect of asbestos on lung epithelial barrier integrity as measured by mannitol permeability. We exposed the monolayer to chryogenically ground, respirable-sized chrysotile asbestos particles. This chrysotile asbestos caused a dose- and time-dependent increase in mannitol permeability across the epithelial monolayer. Increased mannitol permeability occurred both in the presence and in the absence of serum, was not due to cytotoxicity as measured by lactate dehydrogenase release, and was not associated with altered actin cytoskeleton at the light microscopic level. Permeability to 70 kDa neutral dextran also increased after asbestos exposure; however, the absolute permeability to dextran was less than mannitol permeability. Neither latex beads nor tantalum caused any change in permeability, suggesting that our findings are not explained by nonspecific effects of particles. Increased permeability did not reverse in the continued presence of asbestos and persisted even after removing the asbestos. Finally, surface-bound iron did not appear to be necessary for this effect because neither chelating iron with deferoxamine nor iron-loading the asbestos altered the effect on mannitol permeability. These results show that asbestos has direct effects on lung epithelial permeability. Together with the recent observation that asbestos directly increases epithelial fibrinolytic activity, our results suggest a novel mechanism for asbestos-induced lung injury.

Asbestos exposure increases human bronchial epithelial cell fibrinolytic activity

Chronic exposure to asbestos fibers results in fibrotic lung disease. The distal pulmonary epithelium is an early target of asbestos-mediated injury. Local plasmin activity may be important in modulating endoluminal inflammatory responses in the lung. We studied the effects of asbestos exposure on cell-mediated plasma clot lysis as a marker of pericellular plasminogen activation. Exposing human bronchial epithelial (HBE) cells to 100 micrograms/ml of asbestos fibers for 24 h resulted in increased plasma clot lysis. Fibrinolytic activity was augmented in a dose-dependent fashion, was not due to secreted protease, and occurred only when there was direct contact between the plasma clot and the epithelial monolayer. Further analysis showed that asbestos exposure increased HBE cell-associated urokinase-type plasminogen activator (uPA) activity in a time-dependent manner. The increased cell-associated PA activity could be removed by acid washing. The increase in PA activity following asbestos exposure required new protein synthesis because it was abrogated by treatment with either cycloheximide or actinomycin D. Therefore, asbestos exposure increases epithelial-mediated fibrinolysis by augmenting expression of uPA activity at the cell surface by mechanisms that require new RNA and protein synthesis. These observations suggest a novel mechanism whereby exposure of the distal epithelium to inhaled particulates may result in a chronic inflammatory response that culminates in the development of fibrotic lung disease.

Defensins reduce the barrier integrity of a cultured epithelial monolayer without cytotoxicity

Polymorphonuclear leukocytes (PMN) contribute to epithelial injury at sites of inflammation, but their mechanisms of action are incompletely understood. PMN can injure target tissues by oxidative and nonoxidative mechanisms. Included in the nonoxidative mechanisms are defensins (DEF), small (3.5 to 4.0 kD), arginine- and cysteine-rich polypeptides. DEF are bactericidal, fungicidal, viricidal, and tumoricidal, but their ability to contribute to inflammatory injury has not been extensively evaluated. One marker of inflammatory injury is disrupted epithelial barrier integrity. Using Madin-Darby canine kidney (MDCK) epithelial monolayers, we measured the effect of both human and rabbit DEF on barrier integrity using mannitol permeability (Pmann) and transepithelial electrical resistance (Rt). Human DEF (HNP1-3, 2:2:1 molar ratio) increased Pmann in a time- and concentration-dependent manner and Rt fell progressively over a 48-h period after exposure of monolayers to HNP1-3. Rabbit DEF peptide 1 (NP-1) also increased Pmann, but rabbit peptide 5 (NP-5) had no effect on Pmann. To investigate the role of charge, HNP1-3 was added to the monolayers with the polyanions heparin or sulfated dextran. Heparin and sulfated dextran only partially inhibited the increase in Pmann. Fetal bovine serum (FBS), however, completely inhibited the effect of HNP1-3, but this protection was only partially explained by the anionic protein, albumin. The FBS protection was time dependent and was present when FBS was added up to 16 h after exposure to HNP1-3. While both HNP1-3 and NP-1 increased epithelial permeability, neither were cytolytic to MDCK cells as measured by lactate dehydrogenase release.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium-activated phosphatidylcholine-specific phospholipase C and D in MDCK epithelial cells

Calcium ionophore exposure generates diglycerides (DAG) from phosphatidylcholine (PC) hydrolysis in Madin-Darby canine kidney (MDCK) epithelial cells. This study compares calcium ionophore-activated PC hydrolysis with the previously described phorbol ester-stimulated PC hydrolysis pathway using MDCK cells labeled with [14C]-linoleic acid. Lipid species were measured using thin-layer chromatography. DAG resulted in part from PC hydrolysis because DAG increased in cells labeled with [palmitoyl-2-14C]phosphatidylcholine. Neither protein kinase C (PKC) inhibitors nor PKC depletion affected the ionomycin (IONO)-induced increase in DAG. Ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid prevented the increased DAG after IONO but not after phorbol 12,13-dibutyrate (PDBu) exposure. The EGTA effect was reversed by adding excess calcium but was not reversed by adding excess Mg2+. IONO exposure also increased phosphatidic acid (PA) production. The PA was produced by phospholipase D (PLD) because phosphatidylethanol was produced when IONO was added to the cells in the presence of ethanol. Although increasing concentrations of ethanol resulted in progressively less PA, it had no effect on increased DAG after IONO exposure at any time point tested. These data are consistent with both increased phospholipase C (PLC) and increased PLD activity following ionomycin. In contrast to IONO exposure, ethanol completely prevented the increase in DAG after PDBu exposure, consistent with DAG produced by PLD activation. These results demonstrate that calcium activates both PC-specific PLC and PLD in MDCK cells and that the calcium-activated pathway is independent of the previously described PKC activation pathways.

Protamine interaction with the epithelial cell surface

We have previously reported that exposing cultured Madin Darby canine kidney (MDCK) cells to the polycation protamine (PRO) results in increased short-circuit current and decreased barrier integrity as measured by mannitol permeability and transepithelial electrical resistance. To further investigate the interaction of PRO with the surface of epithelial cells, we labeled PRO with [14C] with use of reductive alkylation. [14C]PRO bound to the cells in a biphasic pattern. Approximately 10% of the [14C]PRO was bound to the cells in the first 5 min, followed by an additional 10% that was bound over the next 25 min. No additional [14C]PRO bound to the cells after the initial 30 min. Binding of [14C]PRO was inhibited by "cold" PRO, which suggested specificity. Binding was also inhibited by polyanions, serum, and albumin, agents previously found to protect MDCK cells from PRO-induced injury. The binding of PRO to MDCK cells was not inhibited by incubation of the MDCK cells with neuraminidase, to remove surface sialic acid residues, or with heparinase, to remove surface heparan sulfate, even though metabolic labeling experiments demonstrated that neuraminidase decreased cell sialic acid and heparinase decreased cell heparan sulfate. Neuraminidase and heparinase offered no protection from PRO injury and had no effect themselves on mannitol permeability. Incubation of the cells with trypsin, however, blunted both the binding of PRO to the cells and the increase in mannitol permeability after exposure of the cells to PRO.(ABSTRACT TRUNCATED AT 250 WORDS)

A cytosolic inhibitor of human neutrophil elastase and cathepsin G

The neutrophil serine proteinases elastase and cathepsin G produce connective tissue injury, the extent of which depends on the balance between these enzymes and their inhibitors. The most important of these inhibitors is alpha 1-proteinase inhibitor, a member of a superfamily of homologous proteins known as serpins. Neutrophil cytosol inhibited the activities of human neutrophil elastase and cathepsin G in a dose-dependent fashion. To demonstrate formation of an enzyme-inhibitor complex, we combined 125I-elastase or 125I-cathepsin G with neutrophil cytosol or alpha 1-proteinase inhibitor and analyzed the products by polyacrylamide gel electrophoresis. Unbound elastase and cathepsin G each migrated to an apparent molecular weight of 25 kDa. In the presence of cytosol from neutrophils both radiolabeled enzymes migrated with a relative size of 68 kDa, whereas in the presence of alpha 1-proteinase inhibitor the relative size was 85 kDa. Enzyme-inhibitor complexes were stable in sodium dodecyl sulfate at 100 degrees C but were dissociated by hydrolysis in ammonium hydroxide (1.5 mol/L) at 37 degrees C. Formation of each complex was prevented by pretreatment of elastase or cathepsin G with diisopropylfluorophosphate, indicating that the inhibitor binds to the active site of the enzyme. Exposure of either alpha 1-proteinase inhibitor or neutrophil cytosol to the myeloperoxidase-H2O2-halide system prevented complex formation, suggesting the presence of an oxidizable amino acid at the binding site of the inhibitor. By electrophoretic analysis, the molecular weight of the cytosolic inhibitor was 43 kDa and neutrophils contained approximately 1 attomol of inhibitor per cell. The isoelectric points of the elastase and cathepsin G inhibitor were 5.5-5.9 and inhibitors of the two proteinases coeluted using size exclusion chromatography. These data demonstrate that human neutrophil cytosol contains a single serpinlike protein that inhibits elastase and cathepsin G. The inhibitor may be important in protecting the intracellular environment from proteolytic injury during degranulation.

Outcome after cardiopulmonary resuscitation in a medical intensive care unit

Cardiopulmonary resuscitation (CPR) is often performed in modern critical care units, but its efficacy has not been evaluated in this setting. It is important to evaluate CPR in critical care units because these patients often have multisystem disorders and suffer from diseases reported to carry a poor outcome after CPR. Inappropriate resuscitation of patients in this setting results in increased cost of care (both financial and emotional), with little tangible benefit. To address the question of successful resuscitation in the medical intensive care unit (MICU), we retrospectively reviewed the records of 114 patients who underwent CPR in our MICU over a three-year period. Eighty patients (70 percent) were not successfully resuscitated, 21 patients (18 percent) were successfully resuscitated but died before discharge, and 13 patients (11 percent) survived to leave the hospital. We evaluated a number of prearrest conditions (diagnoses, age, sex, duration of hospitalization, length of ICU stay, and severity of illness as measured by APACHE 2 scores) and arrest conditions (the initial cardiac rhythm and duration of CPR) to determine if the outcome after CPR was influenced by any of these parameters. Among the prearrest conditions, only a diagnosis of hypotension or sepsis and an elevated APACHE 2 acute physiology score were independently associated with a poor outcome after CPR. The only arrest condition found to be independently associated with outcome following CPR was the duration of resuscitative effort (p less than 0.01). The patients who were successfully resuscitated but died before discharge were not different from the patients who were not successfully resuscitated in any parameter that we evaluated. These results demonstrate that CPR can be successful in the MICU and that there are prearrest and arrest parameters which are useful in identifying those patients most likely to benefit from CPR in the critical care setting.

Synergistic effects of a calcium ionophore and activators of protein kinase C on epithelial paracellular permeability

Oxidants reversibly increase the paracellular permeability of Madin Darby canine kidney (MDCK) epithelial cell monolayers, and the decrease in resistance occurs within 10 to 15 min of initiating oxidant exposure. Oxidants also initiate hydrolysis of phosphatidylinositol in MDCK cells, with resultant increases in diacylglycerol and inositol phosphates. Phorbol esters and synthetic diacylglycerols increase the paracellular permeability of MDCK monolayers with a time course similar to the oxidants. In contrast, calcium ionophores increase MDCK monolayer paracellular permeability only after 2 to 3 h of exposure. Because the products of the oxidant-initiated phospholipid hydrolysis would be likely to both activate protein kinase C and increase cell calcium, we asked if ionomycin, a calcium ionophore, and phorbol esters or diacylglycerols, activators of protein kinase C, might not act in concert to alter MDCK monolayer paracellular permeability. When ionomycin was added alone to MDCK monolayers, there was an increase in cell calcium, activation of a lumen negative current, a limited transitory decrease in transepithelial resistance, but no increase in mannitol flux across the monolayers. When phorbol dibutyrate (PDBU) or oleyl acetyl glycerol (OAG) were added to MDCK monolayers, there was no current activated, there was a progressive decrease in transepithelial resistance, and there was an increase in mannitol flux across the monolayers which was evident within 20 to 40 min of adding the agent. When 1 microM ionomycin was added to the monolayers along with PDBU or OAG, there was a synergistic increase in paracellular permeability of the monolayers when compared to addition of ionomycin, PDBU, or OAG alone.(ABSTRACT TRUNCATED AT 250 WORDS)

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A23187 increases permeability of MDCK monolayers independent of phospholipase activation

Changes in intracellular calcium influence epithelial barrier integrity, but the mechanism of action is unknown. One possibility is that calcium may work by increasing phospholipase A2 (PLA2) and/or phospholipase C (PLG) activity. Measuring the mannitol permeability (Pmann) of cultured monolayers of Madin-Darby canine kidney (MDCK) epithelium cells as a measure of barrier integrity, we found that exposure of the monolayers to 5 and 10 microM A23187 produced an increase in Pmann whereas 1 microM A23187 did not. Exposure of MDCK cells labeled with [3H]arachidonate to A23187 resulted in an increase in both PLA2 activity, as measured by an increase in free fatty acids, and in PLC activity, as measured by an increase in diacylglycerol (DAG). The increase in DAG was due to an increase in phosphatidylcholine-specific PLC activity. The relationship of phospholipolysis to Pmann was evaluated further by the use of mepacrine and dexamethasone. Mepacrine (10 microM) decreased PLA2 activity by 60% but had no effect on increased Pmann after exposure to A23187. Preexposure of the monolayers to dexamethasone (10 microM) blocked both PLA2 activity and PLC activity and also prevented the increase in Pmann after exposure to A23187. To evaluate whether this protective effect of dexamethasone was due to PLC blockade, we incubated the cells with the protein kinase C blocker H-7. Incubation with H-7 offered no protection from increased Pmann after A23187. These results demonstrate that increased intracellular calcium decreases the barrier integrity of epithelium and increases both PLA2 and phosphatidylcholine-specific PLC activity. The increase in Pmann, however, appears to occur through mechanisms other than phospholipase activation.

Silica directly increases permeability of alveolar epithelial cells

Alveolar epithelial cell injury and increased alveolar-capillary membrane permeability are important features of acute silicosis. To determine whether silica particles contribute directly to this increased permeability, we measured paracellular permeability of rat alveolar epithelium after exposure to silica, in vitro, using markers of the extracellular space. Silica (Minusil) markedly increased permeability in a dose- and time-dependent manner. This was not the result of cytolytic injury, because lactate dehydrogenase release from monolayers exposed to silica was not increased. Pretreatment of the silica with serum, charged dextrans, or aluminum sulfate blocked the increase in permeability. Scanning electron microscopy demonstrated adherence of the silica to the surface of the alveolar epithelial cells. Thus silica can directly increase permeability of alveolar epithelium.

Protamine increases the permeability of cultured epithelial monolayers

Polycations, including protamine, have been reported to decrease the barrier integrity of cultured rat pulmonary type II epithelial monolayers. In contrast, protamine has been reported to increase the transepithelial electrical resistance of gallbladder epithelium. The present study was done using Madin Darby canine kidney epithelial cells (MDCK) to determine whether the effect of protamine on type II epithelial monolayers was species or organ specific or was dependent on the presence of nonepithelial cells and to investigate the effect of protamine on the actin cytoskeleton. Exposure of MDCK monolayers to protamine resulted in decreased transepithelial electrical resistance (Rt), increased short-circuit current (Isc) across the monolayers, and increased mannitol permeability (Pmann) of the monolayers. The decrease in Rt and increase in Isc was seen only after the addition of protamine to the apical surface of the cells. The importance of charge in this action was supported by the fact that exposure of the monolayer to the polycation poly-L-lysine also resulted in increased Pmann, and both the decreased Rt and increased Pmann seen after the addition of protamine were prevented if the monolayers were exposed in the presence of the polyanions heparin or sulfated dextran. The increase in Pmann appeared to be the result of increased permeability in the paracellular pathway, because increased mannitol uptake by the cells represented only a fraction of the increase in Pmann. Subtle changes in the actin cytoskeleton were seen after exposure of the monolayers to protamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation of chest roentgenograms with pulmonary function and bronchoalveolar lavage in interstitial lung disease

We used the ILO classification for occupational lung disease to determine whether there was any correlation between the type and/or severity of pulmonary infiltration on chest roentgenograms and either pulmonary function tests or the types of inflammatory cells present in BAL fluid in patients with interstitial lung disease. Of the 62 patients evaluated (27 with sarcoidosis, 18 with IPF, and 17 with a CV disease and lung involvement), 49 had irregular linear opacities and 13 had normal chest x-rays. There were no significant correlations between the types of cells present in BAL fluid and the various categories of infiltrate or profusion of the infiltrates within each disease group. In patients with sarcoidosis, more extensive infiltration (profusion) was associated with lower FEV, (p less than 0.01). In patients with IPE, linear opacity type, profusion, and the presence or absence of honeycombing were not related to the severity of pulmonary function abnormalities. We conclude that the ILO classification for analysis of chest roentgenograms can be applied to patients with interstitial lung disease not associated with an occupational exposure and that this approach is useful, especially for communication. However, these data provide no information regarding the inflammatory process in the lung and limited information regarding abnormalities in pulmonary function.

Nodular pulmonary opacities in patients with rheumatoid arthritis. A diagnostic dilemma

Nodular opacities are a well-known pulmonary manifestation of rheumatoid arthritis (RA), occurring most often in seropositive men who smoke and have subcutaneous nodules. In the past 15 years two cases of lung carcinoma presenting as pulmonary nodules have been reported in patients with rheumatoid disease. We present seven patients with seropositive RA and subcutaneous nodules who had new pulmonary nodule(s) noted on chest roentgenograms. All but one were current smokers. Carcinoma was found in all patients at bronchoscopy or thoracotomy. Four patients had solitary nodules (one was cavitary); the remaining three patients had multiple bilateral nodules that cavitated in one case. All patients had interstitial abnormality (peribronchial/vascular thickening) with basal predominance in three, and there was evidence of pleural thickening/fluid in three patients. These results strongly suggest that histologic proof of presumed rheumatoid pulmonary nodules be obtained.

Neutrophil cathepsin G increases calcium flux and inositol polyphosphate production in cultured endothelial cells

Exposure of endothelial cells (ENDO) to human neutrophil cathepsin G (CG) increases albumin flux across the endothelial monolayer. Since calcium influences cell shape and barrier function of ENDO monolayers, the current study was designed to determine if CG acted through alterations in Ca2+ homeostasis in ENDO. The role of Ca2+ in the increased permeability of ENDO monolayers to albumin after exposure to CG was studied by using ENDO monolayers cultured on polycarbonate filters. Exposure of ENDO monolayers to CG in the presence of the Ca2+-antagonist lanthanum partially prevented the increase in albumin flux, but exposure in the presence of agents that block voltage-regulated calcium channels did not block the increase in albumin flux. To monitor the effect of CG on Ca2+-flux, ENDO were labeled with 45Ca2+ and changes in Ca2+ flux were monitored by the release of 45Ca2+. From 1 to 15 minutes after exposure of ENDO to CG, there was increased release of 45Ca2+ compared with control cells. Calcium channel blocking agents did not inhibit the increased release of 45Ca2+, but lanthanum partially blocked the increase. The increased release of Ca2+ appeared to be due, at least in part, to activation of phospholipase C because there was an increase both in inositol polyphosphate species and in diglycerides after incubation of ENDO with CG. These studies support the hypothesis that CG increases the flux of calcium in ENDO, that this increase in Ca2+ flux may result from activation of phospholipase C, and that this system may be involved in the decreased barrier properties of the ENDO after CG exposure.

Neutrophil cathepsin G increases calcium flux and inositol polyphosphate production in cultured endothelial cells

Exposure of endothelial cells (ENDO) to human neutrophil cathepsin G (CG) increases albumin flux across the endothelial monolayer. Since calcium influences cell shape and barrier function of ENDO monolayers, the current study was designed to determine if CG acted through alterations in Ca2+ homeostasis in ENDO. The role of Ca2+ in the increased permeability of ENDO monolayers to albumin after exposure to CG was studied by using ENDO monolayers cultured on polycarbonate filters. Exposure of ENDO monolayers to CG in the presence of the Ca2+-antagonist lanthanum partially prevented the increase in albumin flux, but exposure in the presence of agents that block voltage-regulated calcium channels did not block the increase in albumin flux. To monitor the effect of CG on Ca2+-flux, ENDO were labeled with 45Ca2+ and changes in Ca2+ flux were monitored by the release of 45Ca2+. From 1 to 15 minutes after exposure of ENDO to CG, there was increased release of 45Ca2+ compared with control cells. Calcium channel blocking agents did not inhibit the increased release of 45Ca2+, but lanthanum partially blocked the increase. The increased release of Ca2+ appeared to be due, at least in part, to activation of phospholipase C because there was an increase both in inositol polyphosphate species and in diglycerides after incubation of ENDO with CG. These studies support the hypothesis that CG increases the flux of calcium in ENDO, that this increase in Ca2+ flux may result from activation of phospholipase C, and that this system may be involved in the decreased barrier properties of the ENDO after CG exposure.

Neutrophil cathepsin G increases transendothelial albumin flux

Neutrophils are involved in the development of inflammatory edema in some animal models, but their mechanisms of action are not completely understood. Among injurious agents available for neutrophil-mediated injury are cationic proteins such as cathepsin G. Previous articles have reported that cationic agents decrease the barrier properties of the endothelium both in vivo and in vitro. Using an ex vitro isolated, perfused rabbit lung and a cultured porcine pulmonary artery endothelial cell monolayer (ENDO) as models, we asked whether neutrophil cathepsin G could decrease the barrier properties of the intact vasculature and cultured endothelial monolayers. After the addition of cathepsin G (10 micrograms/ml) to the perfusate of the isolated, perfused lung, there was a fourfold increase in net weight gain after a venous pressure challenge (p less than 0.01). The addition of cathepsin G to a cultured ENDO directly increased the movement of albumin across the monolayers in a dose-dependent fashion (10 micrograms/ml led to a 59% +/- 5% increase, 15 micrograms/ml to a 135% +/- 55% increase, 20 micrograms/ml to a 247% +/- 78% increase, and 30 micrograms/ml to a 381% +/- 89% increase, p less than 0.05 at all concentrations). Heat-inactivation of the enzyme only partially protected the ENDO, but exposure in the presence of either the polyanion heparin or the polyanion dextran sulfate completely protected the ENDO. Normal human serum also protected the ENDO, but serum from two patients with alpha 1-proteinase inhibitor (alpha 1-PI) deficiency was only partially protective. The protection afforded by human serum was time dependent, because addition of the serum 5 or 15 minutes after the addition of cathepsin G offered no protection. Oxidation of alpha 1-PI, as may occur at sites of inflammation, also destroyed its protective effect. Cytotoxic injury of the porcine pulmonary artery endothelial cell monolayer by cathepsin G, which was also prevented by the polyanions, only partially explained these results, because cathepsin G increased albumin transfer across the ENDO at concentrations of 10 to 20 micrograms/ml, which were minimally cytolytic to the ENDO. Additionally, cathepsin G caused cell retraction, with the development of intercellular gaps visible on light microscopy of the ENDO. This effect was also prevented by the polyanions. These results demonstrate that cathepsin G has direct effects on a cultured ENDO that may be caused by the charge or charged site(s) on cathepsin G.

Immune mediators increase adherence of T-lymphocytes to human lung fibroblasts

The purpose of the present study was to determine whether immunological mediators that are known to be released in the lungs of patients with active sarcoidosis might increase the adherence of human T-lymphocytes to human lung fibroblasts. The studies demonstrate that interleukin 1 (IL-1), tumor necrosis factor (TNF), gamma-interferon (IFN), and interleukin 2 (IL-2) increase the adherence of T-lymphocytes to fibroblasts in a dose- and time-dependent manner. An effect of IL-1, TNF, and IFN was observed at concentrations less than 1 ng/ml; an effect of IL-2 was not observed unless greater than or equal to 60 ng/ml of the mediator was used. The effect of the mediators was primarily on the fibroblasts; however, a significant increase in adherence was also observed when the T-lymphocytes were preincubated with the mediators. These observations suggest that there may be an intimate relationship between the immune response and the fibrotic response in the lungs of patients with pulmonary sarcoidosis or in other disorders where tissue fibrosis is mediated by immunological processes.

Neutrophil cathepsin G increases permeability of cultured type II pneumocytes

Neutrophils contribute to inflammatory injury in some types of acute and chronic lung disease. Among the injurious agents released by activated neutrophils are cationic proteins such as cathepsin G that may contribute to edema formation. Using cultured rat type II alveolar epithelium, we examined the effect of human neutrophil cathepsin G on permeability to mannitol and electrical resistance across the cultured epithelium. Monolayers maintained in control media alone had constant permeability to mannitol (4.5 +/- 0.3 X 10(-3) cm/h at base line and 4.4 +/- 0.3 X 10(-3) cm/h after 2 h). When monolayers were exposed to cathepsin G at concentrations of 5, 10, and 20 micrograms/ml, there was a progressive increase in mannitol permeability (120 +/- 26% increase at 5 micrograms/ml, 174 +/- 40% increase at 10 micrograms/ml and 301 + 116% increase at 20 micrograms/ml, P less than 0.001). The effect of cathepsin G on mannitol permeability was blocked by the presence of the polyanion-sulfated dextran, and the polycation protamine also increased permeability to mannitol 57 +/- 5% (P less than 0.001), suggesting a role for charge in this effect. Cathepsin G exposure also resulted in a progressive decrease in electrical resistance (67 +/- 2% base line after 15 min, 55 +/- 1% after 30 min, and 43 +/- 2% after 60 min). Cathepsin G at these concentrations was not cytolytic to the cells as measured by lactate dedrogenase release. These functional alterations were accompanied by increase in intercellular gaps in the monolayers seen on scanning electron microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

An unusual cause of massive pleural effusion in pregnancy

A 40 year old woman at 30 weeks of her eighth pregnancy presented with acute onset of dyspnoea and a large left pleural effusion after the onset of premature labour. A barium enema showed diaphragmatic rupture with intestinal contents in the thorax. Repair was accomplished through simultaneous left subcostal and thoracic incisions.