Update on Novel Targeted Therapy for Pleural Organization and Fibrosis

Pleural injury and subsequent loculation is characterized by acute injury, sustained inflammation and, when severe, pathologic tissue reorganization. While fibrin deposition is a normal part of the injury response, disordered fibrin turnover can promote pleural loculation and, when unresolved, fibrosis of the affected area. Within this review, we present a brief discussion of the current IPFT therapies, including scuPA, for the treatment of pathologic fibrin deposition and empyema. We also discuss endogenously expressed PAI-1 and how it may affect the efficacy of IPFT therapies. We further delineate the role of pleural mesothelial cells in the progression of pleural injury and subsequent pleural remodeling resulting from matrix deposition. We also describe how pleural mesothelial cells promote pleural fibrosis as myofibroblasts via mesomesenchymal transition. Finally, we discuss novel therapeutic targets which focus on blocking and/or reversing the myofibroblast differentiation of pleural mesothelial cells for the treatment of pleural fibrosis.

Different patterns of pneumothorax in patients with soft tissue tumors treated with pazopanib: A case series analysis

To investigate pneumothorax patterns in pazopanib treatment by focusing on the positional relationship between the visceral pleura and metastatic lung tumor, we examined 20 patients with advanced soft tissue tumors who developed lung metastases and underwent pazopanib treatment between 2012 and 2019. Pneumothorax was classified into two types based on the location of the metastatic lesion around the visceral pleural area before pazopanib treatment: subpleural type, within 5 mm from the pleura; and central type, >5 mm from the pleura. We investigated the rates of pneumothorax and the associated risk factors. Five patients experienced pneumothorax (three subpleural and two central types). Cavitation preceded pneumothorax in 83% of patients and led to connection of the cavitated cyst of the metastatic lesion to the chest cavity in the shorter term in patients with the subpleural type. Conversely, a more gradual increase in the cavity size and sudden cyst rupture were observed in the central type. The risk factors for pneumothorax were cavitation after initiating pazopanib and intervention before pazopanib, either ablation or surgery. The location of the metastatic lesions was not a risk factor for the occurrence of pneumothorax. In conclusion, pneumothorax is an adverse event associated with pazopanib treatment. Therefore, attention must be paid to predisposing factors such as the formation of cavitation after pazopanib initiation and previous interventions to the lungs. Moreover, because subpleural pneumothorax tends to occur earlier than the central type, a different time course can be anticipated based on the positional relationships of the metastatic lesions to the visceral pleura.

Evaluation of pleural lesions after pleurodesis with OK-432 by fluorodeoxyglucose-positron emission tomography/CT

OBJECTIVE

This study aimed to determine changes in FDG-PET/CT after pleurodesis with OK-432 and to investigate differences in the changes between non-malignant and malignant lesions.

METHODS

Study participants were 17 patients with a history of malignant chest disease who underwent FDG-PET/CT after pleurodesis using OK-432 and in whom pleural lesions were determined to be non-malignant (n = 8) or malignant (n = 9). FDG uptake (SUV_max) was counted on all pleural lesions. CT findings (CT attenuation, shape) of pleural lesions with increased FDG uptake were evaluated.

RESULTS

The number of patients with increased FDG uptake in the pleura differed significantly between the non-malignant group (3/8) and malignant group (9/9) (p < 0.01) The mean SUV_max of non-malignant lesions with increased FDG uptake was 2.3 ± 0.7 vs. 6.2 ± 2.2 in malignant lesions, for a significant difference (p < 0.01). The mean CT attenuation of lesions was 36 ± 11 HU in the non-malignant group and 34 ± 14 HU in the malignant group, a difference that was not significant (p = 0.91). There was a significant difference in nodular and linear shapes between non-malignant and malignant lesions (p < 0.01). All non-malignant lesions were linear.

CONCLUSIONS

Positive FDG uptake was shown in non-malignant pleural lesions as well as in malignant pleural lesions after pleurodesis using OK-432. Combined analysis of FDG accumulation and CT morphology is helpful to distinguish between benign and malignant lesions.

Mesothelioma: Scientific clues for prevention, diagnosis, and therapy

Mesothelioma affects mostly older individuals who have been occupationally exposed to asbestos. The global mesothelioma incidence and mortality rates are unknown, because data are not available from developing countries that continue to use large amounts of asbestos. The incidence rate of mesothelioma has decreased in Australia, the United States, and Western Europe, where the use of asbestos was banned or strictly regulated in the 1970s and 1980s, demonstrating the value of these preventive measures. However, in these same countries, the overall number of deaths from mesothelioma has not decreased as the size of the population and the percentage of old people have increased. Moreover, hotspots of mesothelioma may occur when carcinogenic fibers that are present in the environment are disturbed as rural areas are being developed. Novel immunohistochemical and molecular markers have improved the accuracy of diagnosis; however, about 14% (high-resource countries) to 50% (developing countries) of mesothelioma diagnoses are incorrect, resulting in inadequate treatment and complicating epidemiological studies. The discovery that germline BRCA1-asssociated protein 1 (BAP1) mutations cause mesothelioma and other cancers (BAP1 cancer syndrome) elucidated some of the key pathogenic mechanisms, and treatments targeting these molecular mechanisms and/or modulating the immune response are being tested. The role of surgery in pleural mesothelioma is controversial as it is difficult to predict who will benefit from aggressive management, even when local therapies are added to existing or novel systemic treatments. Treatment outcomes are improving, however, for peritoneal mesothelioma. Multidisciplinary international collaboration will be necessary to improve prevention, early detection, and treatment.

Corticosteroids for tuberculous pleurisy

BACKGROUND

Corticosteroids used in addition to antituberculous therapy have been reported to benefit people with tuberculous pleurisy. However, research findings are inconsistent and raise doubt as to whether such treatment is worthwhile. There is also concern regarding the potential adverse effects of corticosteroids, especially in HIV-positive people.

OBJECTIVES

To evaluate the effects of adding corticosteroids to drug regimens for tuberculous pleural effusion.

SEARCH METHODS

In April 2016, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (the Cochrane Library), MEDLINE, Embase, LILACS, Current Controlled Trials, and the reference lists of articles identified by the literature search.

SELECTION CRITERIA

Randomized controlled trials (RCTs) and quasi-RCTs that compared any corticosteroid with no treatment, placebo, or other active treatment (both groups should have received the same antituberculous drug regimen) in people diagnosed with tuberculous pleurisy.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results, extracted data from the included trials, and assessed trial methodological quality using the Cochrane 'Risk of bias' tool. We analysed the data using risk ratios (RR) with 95% confidence intervals (CIs). We applied the fixed-effect model in the absence of statistically significant heterogeneity.

MAIN RESULTS

Six trials with 590 participants met the inclusion criteria, which were conducted in Asia (three trials), Africa (two trials), and Europe (one trial). Two trials were in HIV-negative people, one trial was in HIV-positive people, and three trials did not report HIV status.Corticosteroids may reduce the time to resolution of pleural effusion. Risk of residual pleural effusion on chest X-ray was reduced by 45% at eight weeks (RR 0.54, 95% CI 0.37 to 0.78; 237 participants, 2 trials, low certainty evidence), and 65% at 24 weeks (RR 0.35, 95% CI 0.18 to 0.66; 237 participants, 2 trials, low certainty evidence).Compared with control, corticosteroids may reduce the risk of having pleural changes (such as pleural thickening or pleural adhesions), on chest X-ray at the end of follow-up by almost one third (RR 0.72, 95% CI 0.57 to 0.92; 393 participants, 5 trials,low certainty evidence), which translates to an absolute risk reduction of 16%.One trial reported deaths in people that were HIV-positive, with no obvious difference between the groups; the trial authors' analysis suggests that the deaths observed in this trial were related to HIV disease rather than pleural TB (RR 0.91, 95% CI 0.64 to 1.31; 197 participants, 1 trial).We found limited data on long-term functional respiratory impairment on 187 people in two trials, which reported that average percentage predicted forced vital capacity was similar in the group receiving prednisolone and in the control group (very low certainty evidence).The risk of adverse events that led to discontinuation of the trial drug was higher in people with pleural TB receiving corticosteroids (RR 2.78, 95% CI 1.11 to 6.94; 587 participants, 6 trials, low certainty evidence). The trial in HIV-positive people reported on six different HIV-related infections, with no obvious differences. However, cases of Kaposi's sarcoma were only seen in the corticosteroid group (with 6/99 cases in the steroid group compared to 0/98 in the control group) (very low certainty evidence).

AUTHORS' CONCLUSIONS

Long-term respiratory function is potentially the most important outcome for assessing the effects of adjunctive treatments for people with pleural TB. However, the information on the impact of pleural TB on long-term respiratory function is unknown and could be eclipsed by other risk factors, such as concurrent pulmonary TB, smoking, and HIV. This probably needs to be quantified to help decide whether further trials of corticosteroids for pleural TB would be worthwhile.

[PREVENTION AND CORRECTION OF PULMONARY COMPLICATIONS FOR SEVERE ACUTE PANCREATITIS]

Increased of proinflammatory cytokines levels, including interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha) on severe acute pancreatitis causes vasodilatation, increased permeability of the wall, accumulation of fluid in lung tissue and pleural sinuses. Transudate from acute parapancreatyc clusters of hot liquid and abdomen falls into the chest cavity through microscopic defects in the diaphragm due to the formation of pathological pleural-peritoneal connections or the relevant pressure gradient between the abdominal and pleural cavities. Remediation and removal of acute parapancreatyc clusters combined with the use of a multicomponent drug infusion therapy Cytoflavin provide a reduction in the frequency of pulmonary complications of acute pancreatitis from 48.3 to 31.0%. Use of the drug Cytoflavin reduces the severity of endogenous intoxication and mortality from acute lung injury from 12.9 to 6.1%.

Lubricating recovery of damaged pleural mesothelium: effect of time and of phosphatidylcholines

Effect of time and phosphatidylcholines (PCs) on lubrication of damaged mesothelium has been investigated. Marked increase in coefficient of kinetic friction (μ) of pleural specimens after mesothelial blotting and rewetting decreased by 23.4±3.5%, 41.8±3.8%, and 40.5±2.7% after 30min, 1h, and 2h. Hence, damaged mesothelium is able to partially reset lubricating molecules on its surface. Increase in μ of post-blotting Ringer 2h after addition of unsaturated PCs (3mg/ml) decreased a little more than after 2h Ringer. Effects of unsaturated and saturated PCs were similar, contrary to expectation raised by their different percentage in pleural and alveolar lavage. Effect of PCs did not increase at 6mg/ml, and was nil at 0.4mg/ml. Increase of μ after short phospholipase treatment decreased by 45.9±2.0% after 2h Ringer, and a little more after addition of unsaturated or saturated PCs. Hence, PCs, as other phospholipids, have a small effect, likely because of difficulty in resetting their relationships with main lubricating molecules.

[Chrysotile-asbestos induces cytogenetic effects in the rat's mesothelium in vitro and in vivo]

Under cultivation of rat peritoneal mesothelial cells in vitro in them there are appeared signs of the genomic instability, evidencing their transformation: increasing of the number of both binucleated cells with micronuclei and polynuclear cells and the increase of sizes and polymorphism. Asbestos greatly accelerates this process. Asbestos-induced carcinogenesis in vivo is accompanied in pleural mesothelium in the rats there also revealed with similar signs of genomic instability and cellular transformation.

Effectiveness and safety of iodopovidone in an experimental pleurodesis model

OBJECTIVES

Chemical pleurodesis is an important therapeutic tool to control recurrent malignant pleural effusion. Among the various sclerosing agents, iodopovidone is considered effective and safe. However, in a recent study, ocular changes were described after iodopovidone was used in recurrent pneumothorax. The aim of the study was to evaluate the efficacy and morbidity of iodopovidone pleurodesis in an experimental model.

METHODS

New Zealand rabbits were submitted to intrapleural injection of iodopovidone at concentrations of 2%, 4% and 10%. Biochemical (lactic dehydrogenase, proteins, triiodothyronine, free thyroxine, urea and creatinine) and immunological (Interleukin-8 [IL-8], VEGF and TGFβ) parameters were measured in the pleural fluid and blood. After 1, 3, 7, 14 and 28 days, groups of animals were euthanized, and macro- (pleura) and microscopic (pleura and retina) analyses were performed.

RESULTS

An early pleural inflammatory response with low systemic repercussion was observed without corresponding changes in thyroid or renal function. The higher concentrations (4% and 10%) correlated with greater initial exudation, and maximum pleural thickening was observed after 28 days. No changes were observed in the retinal pigment epithelium of the rabbits.

CONCLUSION

Iodopovidone is considered to be an effective and safe sclerosing agent in this animal model. However, its efficacy, tolerance and safety in humans should be further evaluated.

Decreased expression of GATA4 in the diaphragm of nitrofen-induced congenital diaphragmatic hernia

BACKGROUND

The molecular mechanisms underlying the diaphragmatic defect in congenital diaphragmatic hernia (CDH) are still poorly understood. The transcription factor GATA4 is essential for normal development of the diaphragm. Recently, mutations in the GATA4 gene have been linked to human and rodent CDH. We hypothesized that diaphragmatic GATA4 expression is downregulated in the nitrofen CDH model.

METHODS

Pregnant rats received Nitrofen or vehicle on day 9 of gestation (D9). Fetuses were sacrificed on D13, D18, or D21. Pleuroperitoneal folds (n=20) and fetal diaphragms (n=40) were (micro) dissected and divided into CDH group and controls. RNA and protein were extracted. GATA4 mRNA levels were determined by real-time PCR. Protein levels were determined by ELISA and Immunohistochemistry.

RESULTS

mRNA levels and Protein levels were significantly decreased in the CDH group compared to controls on D13 (mRNA 15.96±6.99 vs. 38.10±5.01, p<0.05), D18 (mRNA 10.45±1.84 vs. 17.68±2.11, Protein 2.59±0.06 vs. 4.58±0.35 p<0.05) and D21 (mRNA 4.31±0.83 vs. 6.87±0.88, Protein 0.16±0.08 vs. 1.26±0.49, p<0.05). Immunoreactivity of GATA4 was markedly decreased in CDH-diaphragms on D13, D18, and D21.

CONCLUSIONS

We provide evidence for the first time that diaphragmatic expression of GATA4 is downregulated in the nitrofen model, suggesting that decreased expression of GATA4 may impair diaphragmatic development in nitrofen-induced CDH.

IGF-1 alters the human parietal pleural electrochemical profile by inhibiting ion trans-cellular transportation after interaction with its receptor

OBJECTIVE

The effect of IGF-1 in the human pleural permeability and the underlying mechanisms involved were investigated.

DESIGN

Specimens from thoracic surgical patients were mounted in Ussing chambers. Solutions containing IGF-1 (1 nM-100 nM) and IGF-1 Receptor Inhibitor (1 μΜ), amiloride 10 μM (Na(+) channel blocker) and ouabain 1 mM (Na(+)-K(+) pump inhibitor) were used in order to investigate receptor and ion transporter involvement respectively. Trans-mesothelial Resistance (R(TM)) across the pleural membrane was determined as a permeability indicator. Immunohistochemistry for IGF-1 receptors was performed.

RESULTS

IGF-1 increased R(TM) when added on the interstitial surface for all concentrations (p=.008, 1 nM-100 nM) and decreased it on the mesothelial surface for higher concentrations (p=.046, 100 nM). Amiloride and ouabain inhibited this effect. The IGF-1 Receptor Inhibitor also totally inhibited this effect. Immonuhistochemistry demonstrated the presence of IGF-1 receptors in the pleura.

CONCLUSIONS

It is concluded that IGF-1 changes the electrophysiology of the human parietal pleura by hindering the normal ion transportation and therefore the pleural fluid recycling process. This event is achieved after IGF-1 interaction with its receptor which is present in the human pleura.

Clinical importance of angiogenic cytokines, fibrinolytic activity and effusion size in parapneumonic effusions

OBJECTIVE

To investigate the relationship among angiogenic cytokines, fibrinolytic activity and effusion size in parapneumonic effusion (PPE) and their clinical importance.

METHODS

From January 2008 through December 2010, 26 uncomplicated (UPPE) and 38 complicated (CPPE) PPE were studied. Based on chest ultrasonography, there were non-loculated in 30, uni-loculated in 12, and multi-loculated effusions in 22 patients. The effusion size radiological scores, and effusion vascular endothelial growth factor (VEGF), interleukin (IL)-8, plasminogen activator inhibitor type-1 (PAI-1) and tissue type plasminogen activator (tPA) were measured on admission. Treatment outcome and pleural fibrosis, defined as radiological residual pleural thickening (RPT), were assessed at 6-month follow-up.

RESULTS

The effusion size and effusion VEGF, IL-8 and PAI-1/tPA ratio were significantly higher in CPPE than in UPPE, and significantly higher in multi-loculated PPE than in non-locualted and uni-loculated PPE, respectively. VEGF (cutoff value 1975 pg/ml) and IL-8 (cutoff value 1937 pg/ml) seemed best to discriminate between UPPE and CPPE. VEGF, IL-8 and effusion size correlated positively with PAI-1/tPA ratio in both UPPE and CPPE. Moreover, the level of VEGF, but not IL-8, correlated positively with effusion size in all patients (r = 0.79, p<0.001) and in UPPE (r = 0.64, p<0.001) and CPPE (r = 0.71, p<0.001) groups. The patients with higher VEGF or greater effusion were prone to have medical treatment failure (n = 10; VEGF, odds ratio 1.01, p = 0.02; effusion size, odds ratio 1.26, p = 0.01). Additionally, ten patients with RPT had larger effusion size and higher levels of VEGF and PAI-1/tPA ratio than did those without.

CONCLUSIONS

In PPE, VEGF and IL-8 levels are valuable to identify CPPE, and higher VEGF level or larger effusion is associated with decreased fibrinolytic activity, development of pleural loculation and fibrosis, and higher risk of medical treatment failure.

[Isolation of Shewanella algae from pleural exudate of patient with pneumonia]

AIM

Clinical-microbiological description of the first case in Russia of isolation of S. algae bacteria from clinical material.

MATERIALS AND METHODS

Patient P., 23 years of age, diagnosis: right-sided distal pneumonia, severe course; parapneumonic empyema of pleura. Bacteria isolation, cultural and biochemical tests differentiating S. algae and Shewanella putrefaciens were performed according to Holt H.M. et al., 2005. Identification of bacteria, tests of sensitivity to antibiotics were carried out by automatic system Vitek 2 (bioMerieux) and additionally by disc-diffusion method.

RESULTS

S. algae in association with Serratia marcescens were isolated from pleural exudate of the patient with pneumonia. S. algae bacteria had typical taxonomical features and pathogenicity factors (lipase, gelatinase, beta-hemolysin); were resistant to benzylpenicillin, amoxicillin, cefazolin and sensitive to other beta-lactam antibiotics, aminoglycosides, fluoroquinolones, macrolides, tetracycline.

CONCLUSION

S. algae bacteria isolated from pleural exudate of the patient with pneumonia are etiologically significant in parapneumonic empyema of pleura.

Localized pleural thickening: smoking and exposure to Libby vermiculite

There is limited research on the combined effects of smoking and asbestos exposure on risk of localized pleural thickening (LPT). This analysis uses data from the Marysville cohort of workers occupationally exposed to Libby amphibole asbestos (LAA). Workers were interviewed to obtain work and health history, including ever/never smoking and chest X-rays. Cumulative exposure estimates were developed on the basis of fiber measurements from the plant and work history. Benchmark concentration (BMC) methodology was used to evaluate the exposure-response relationship for exposure to LAA and a 10% increased risk of LPT, considering potential confounders and statistical model forms. There were 12 LPT cases among 118 workers in the selected study population. The mean exposure was 0.42 (SD=0.77) fibers/cc-year, and the prevalence of smoking history was 75.0% among cases and 51.9% among non-cases. When controlling for LAA exposure, smoking history was of borderline statistical significance (P-value=0.099), and its inclusion improved model fit, as measured by Akaike's Information Criterion. A comparison of BMC estimates was made to gauge the potential effect of smoking status. The BMC was 0.36 fibers/cc-year, overall. The BMC for non-smokers was approximately three times as high (1.02 fibers/cc-year) as that for the full cohort, whereas the BMC for smokers was about 1/2 that of the full cohort (0.17 fibers/cc-year).

Histone deacetylase inhibitor m-carboxycinnamic acid bis-hydroxamide attenuates plasminogen activator inhibitor-1 expression in human pleural mesothelial cells

Plasminogen activator inhibitor-1 (PAI-1), primarily up-regulated by transforming growth factor (TGF)-β, is essential in the development of fibrosis. Histone deacetylase (HDAC) was shown to modulate gene expression and fibrogenesis in various tissues. However, the implications of HDAC in terms of PAI-1 expression and pleural fibrosis remain unclear. In this study, we examined the effects of m-carboxycinnamic acid bis-hydroxamide (CBHA), a hybrid-polar HDAC inhibitor, on the TGF-β1-induced expression of PAI-1 in a human pleural mesothelial cell line (MeT-5A). MeT-5A cells were treated with TGF-β1 in the presence or absence of CBHA. We assayed the expression and stability of PAI-1 mRNA and protein, PAI-1 promoter activity, the activation of Smad signaling, the protein-protein interactions of Smads with transcriptional cofactors Sp1 and coactivator p300, and the expression of the mRNA-stabilizing protein nucleolin. The results indicate that CBHA significantly inhibited TGF-β1-induced PAI-1 mRNA and protein expression, and attenuated PAI-1 promoter activity in MeT-5A cells. CBHA abrogated TGF-β1-induced Smad4 nuclear translocation, but not Smad2/3 activation. Furthermore, the association of Smad4 with p300, but not with Sp1, was disrupted by CBHA. Alternatively, CBHA suppressed TGF-β1-induced nucleolin expression, and thereby destabilized PAI-1 mRNA and decreased PAI-1 protein concentrations. These findings suggest that the inhibition of HDAC activity by CBHA may attenuate PAI-1 expression through the modulation of cellular signaling at multiple levels. Given the down-regulating effect of CBHA on PAI-1 expression, HDAC inhibitors should be tested further in animal models as potential therapeutic agents for pleural fibrosis.

[DNA damage in human pleural mesothelial cells induced by exposure to carbon nanotubes]

OBJECTIVES

Nanomaterials are currently used in electronics, industrial materials, cosmetics, and medicine because they have useful physicochemical properties, such as strength, conductivity, durability, and chemical stability. As these materials have become widespread, many questions have arisen regarding their effects on health and the environment. In particular, recent studies have demonstrated that carbon nanotubes (CNTs) cause significant inflammation and mesothelioma in vivo. In this study, we investigated the potential risk posed by singlewalled carbon nanotube (SWCNT) and multiwalled carbon nanotube (MWCNT) exposure in human pleural mesothelial cells.

METHODS

CNT cytotoxicity was determined by a trypan blue exclusion assay, and DNA damage was detected by an alkaline comet assay. The concentration of 8-oxodeoxyguanosine (8-OHdG) in DNA was measured by high perhormance liquid chromatography with electrochemical detection. The expression of base excision repair enzymes in the cell was estimated by immunoblot analysis.

RESULTS

We observed inhibitory effects on cell proliferation and the induction of DNA damage following exposure of cells to purified CNTs that were suspended in dispersion medium. However, accumulation of 8-OHdG in DNA was not found. In addition, the expression levels of base excision enzymes that are involved in hOGG1, hMTH1, and MYH in MeT-5A cells remained unchanged for 24 h after carbon nanotube exposure.

CONCLUSIONS

CNTs significantly inhibit cell proliferation and decrease DNA damage in human pleural mesothelial cells. Our results indicate that the mechanism of CNT-induced genotoxicity is different from that following exposure to reactive oxygen species, which causes oxidative DNA modifications and 8-OHdG production. Further investigation is required to characterize the specific DNA mutations that occur following CNT exposure.

Effect of histamine on the electrophysiology of the human parietal pleura

INTRODUCTION

Histamine is involved in the pathogenesis of numerous diseases and regulates the permeability of different tissues. The aim of this study is to investigate the effects of histamine on the electrophysiology of human parietal pleura and the underlying mechanisms involved.

MATERIALS AND METHODS

Pleural specimens were obtained from patients subjected to thoracic surgery and were mounted in Ussing chambers. Histamine solutions (1μM to 1mM) were applied in native and pretreated specimens with dimetindene maleate, cetirizine, ranitidine, amiloride and ouabain. Trans-mesothelial resistance was determined (R(TM)).

RESULTS

Histamine induced a rapid R(TM) increase on the mesothelial (p = 0.008) and a decrease on the interstitial surface (p = 0.029). This effect was dose-dependent and was totally abolished by dimetindene maleate, cetirizine and amiloride and partially by ranitidine and ouabain.

CONCLUSIONS

Histamine induces acute electrochemical changes in human pleura mainly via interaction with the H(1) and partially with the H(2) histamine receptors. It also interferes with trans-cellular permeability and therefore may participate in pleural fluid recycling.

The current data on nanoparticles and pleura

Nanoparticle is the general name given to particles with a size between 0.1 nm and 100 nm. Carbon nanotubes, which have been the focus of many studies recently, are a new type of technological crystal carbon, having specific physical and chemical properties and being used in a wide array of fields from electronics to medicine. To date, the effects of carbon nanotubes over various organs including the lungs have been investigated by many studies, while their influence on pleura has been analyzed only by a limited number of animal and in vitro studies. The current data on the effects of nanoparticles and particularly carbon nanotubes to pleura is reviewed in this article.

Pleural effects of indium phosphide in B6C3F1 mice: nonfibrous particulate induced pleural fibrosis

The mechanism(s) by which chronic inhalation of indium phosphide (InP) particles causes pleural fibrosis is not known. Few studies of InP pleural toxicity have been conducted because of the challenges in conducting particulate inhalation exposures, and because the pleural lesions developed slowly over the 2-year inhalation study. The authors investigated whether InP (1 mg/kg) administered by a single oropharyngeal aspiration would cause pleural fibrosis in male B6C3F1 mice. By 28 days after treatment, protein and lactate dehydrogenase (LDH) were significantly increased in bronchoalveolar lavage fluid (BALF), but were unchanged in pleural lavage fluid (PLF). A pronounced pleural effusion characterized by significant increases in cytokines and a 3.7-fold increase in cell number was detected 28 days after InP treatment. Aspiration of soluble InCl(3) caused a similar delayed pleural effusion; however, other soluble metals, insoluble particles, and fibers did not. The effusion caused by InP was accompanied by areas of pleural thickening and inflammation at day 28, and by pleural fibrosis at day 98. Aspiration of InP produced pleural fibrosis that was histologically similar to lesions caused by chronic inhalation exposure, and in a shorter time period. This oropharyngeal aspiration model was used to provide an initial characterization of the progression of pleural lesions caused by InP.

Inhaled carbon nanotubes reach the subpleural tissue in mice

Carbon nanotubes are shaped like fibres and can stimulate inflammation at the surface of the peritoneum when injected into the abdominal cavity of mice, raising concerns that inhaled nanotubes may cause pleural fibrosis and/or mesothelioma. Here, we show that multiwalled carbon nanotubes reach the subpleura in mice after a single inhalation exposure of 30 mg m(-3) for 6 h. Nanotubes were embedded in the subpleural wall and within subpleural macrophages. Mononuclear cell aggregates on the pleural surface increased in number and size after 1 day and nanotube-containing macrophages were observed within these foci. Subpleural fibrosis unique to this form of nanotubes increased after 2 and 6 weeks following inhalation. None of these effects was seen in mice that inhaled carbon black nanoparticles or a lower dose of nanotubes (1 mg m(-3)). This work suggests that minimizing inhalation of nanotubes during handling is prudent until further long-term assessments are conducted.

Dexamethasone decreases the transmesothelial electrical resistance of the parietal and visceral pleura

The effect of dexamethasone on the transmesothelial electrical resistance (R(TM)) of sheep pleura was investigated by Ussing chamber experiments. Our results show that dexamethasone decreases the R(TM) of sheep pleurae, in part by stimulation of glucocorticoid receptors. This finding may be of importance in regard to the faster resolution of corticosteroid-treated pleural effusions.

Alterations in gene expression in human mesothelial cells correlate with mineral pathogenicity

Human mesothelial cells (LP9/TERT-1) were exposed to low and high (15 and 75 microm(2)/cm(2) dish) equal surface area concentrations of crocidolite asbestos, nonfibrous talc, fine titanium dioxide (TiO2), or glass beads for 8 or 24 hours. RNA was then isolated for Affymetrix microarrays, GeneSifter analysis and QRT-PCR. Gene changes by asbestos were concentration- and time-dependent. At low nontoxic concentrations, asbestos caused significant changes in mRNA expression of 29 genes at 8 hours and of 205 genes at 24 hours, whereas changes in mRNA levels of 236 genes occurred in cells exposed to high concentrations of asbestos for 8 hours. Human primary pleural mesothelial cells also showed the same patterns of increased gene expression by asbestos. Nonfibrous talc at low concentrations in LP9/TERT-1 mesothelial cells caused increased expression of 1 gene Activating Transcription Factor 3 (ATF3) at 8 hours and no changes at 24 hours, whereas expression levels of 30 genes were elevated at 8 hours at high talc concentrations. Fine TiO2 or glass beads caused no changes in gene expression. In human ovarian epithelial (IOSE) cells, asbestos at high concentrations elevated expression of two genes (NR4A2, MIP2) at 8 hours and 16 genes at 24 hours that were distinct from those elevated in mesothelial cells. Since ATF3 was the most highly expressed gene by asbestos, its functional importance in cytokine production by LP9/TERT-1 cells was assessed using siRNA approaches. Results reveal that ATF3 modulates production of inflammatory cytokines (IL-1 beta, IL-13, G-CSF) and growth factors (VEGF and PDGF-BB) in human mesothelial cells.

Malignant pleural effusion and talc pleurodesis. Experimental model regarding early kinetics of talc particle dissemination in the chest after experimental talc pleurodesis

PURPOSE

Talc remains a commonly used agent for pleurodesis malignant pleural effusion. Nevertheless, it is associated with a 3-9% incidence of pulmonary reactions ranging from simple pneumonitis to acute respiratory distress syndrome (ARDS). The underlying lung pathology and the size and rate of talc particle dissemination have been implicated as the cause of these complications. There seems to be an acknowledged lack of evidence regarding detailed very early intrathoracic talc particle migration.

MATERIALS AND METHODS

Thirty white male New Zealand rabbits underwent experimental pleurodesis and were randomly assigned to 3 (A, B, C) study groups (10 in each group). Rabbits were sacrificed 6, 12 and 18 h after talc administration. Samples from both lungs, mediastinum and parietal pleura were obtained. The number of talc crystals (m) deposited was counted and averaged along all slices of the various tissue samples.

RESULTS

A high degree of early talc deposition and subsequent epithelial injury in all examined tissues was observed. Diffuse talc deposition occurred in both lungs, but in a different manner. On the side of talc administration, talc particles were deposited in a time-dependent fashion. On the contralateral side, talc was rapidly deposited during the first hours after the procedure, then the rate of deposition decreased, and increased again between 12 and 18 h after the procedure.

CONCLUSION

Large-sized talc particles are deposited on both lungs very early after pleurodesis. At the same time inflammatory pulmonary changes appear bilaterally. Despite contradicting data in the literature, these findings should always be kept in mind when performing this procedure in high risk patients.

Anti-inflammatory activity of oleanolic acid by inhibition of secretory phospholipase A2

Oleanolic acid, a triterpenoid known for its anti-inflammatory properties, is commonly present in several medicinal plants. The present study evaluated the effect of oleanolic acid on sPLA (2), a key enzyme in inflammatory reactions. Oleanolic acid inhibited sPLA (2) activities of human synovial fluid (HSF), human pleural fluid (HPF) and VIPERA RUSSELLI (VRV-PL-V) and NAJA NAJA (NN-PL-I) snake venoms in a concentration-dependent manner. The IC (50) values of sPLA (2) from these sources ranged from 3.08 to 7.78 muM. Increasing calcium (Ca (2+)) concentrations from 2.5 to 15 mM and substrate concentration up to 180 nM did not affect the level of inhibition. Oleanolic acid enhanced the relative intrinsic fluorescence intensity of sPLA (2) (VRV-PL-V). In the presence of oleanolic acid, an apparent shift in the far UV-CD spectrum of sPLA (2) was observed. These studies indicate direct interaction with the enzyme and formation of an sPLA (2)-oleanolic acid complex. The complex formed resulted in irreversible inhibition of sPLA (2). Oleanolic acid inhibited indirect hemolytic activity and mouse paw edema induced by sPLA (2). Inhibition of IN VITRO and IN VIVO sPLA (2) activity by oleanolic acid explains the observed anti-inflammatory properties of several oleanolic acid-containing medicinal plants.

Orally ingested chrysotile asbestos affects rat lungs and pleura

The authors designed this study to show the effects of orally ingested asbestos on the lungs and pleura. They designated 3 groups of rats: group A (n = 18) was given 1.5 g/L asbestos in water, group B (n = 18) was given 3 g/L asbestos in water, and group C (n = 15), as a control group, was given only water. Histopathological evaluation of lungs and pleura of the rats after 6 months revealed significant mesothelial proliferation and asbestos bodies. After 9 months, more rats exhibited mesothelial proliferation in group B than in group A (p < .05). The number of rats with asbestos bodies in their lungs was greater in group B than in group A. More rats in group B than in group A had asbestos in their spleen. The authors observed mesothelial proliferation in all group B rats at the end of 12 months. Ingested asbestos traveled from the gastrointestinal system to the lungs, likely via a lymphohematological route, leading to mesothelial proliferation, which may lead to malignancies.

[The tactic of targeting the parietal pleura for controlling malignant pleural effusion]

Based on a hypothesis that the most effective target area for controlling malignant pleural effusion is the parietal pleura, the author has selectively carried out the multimodality treatment with limited operations combined with parietal pleurectomy (PL) followed by paclitaxel administered by 24-hour intrathoracic infusion and systemic chemotherapy. Seven patients with carcinomatous pleuritis were enrolled in the study. During a median follow-up period of 22 months, malignant effusion was controlled successfully in all patients. Although the imbalance on assessment and small sample size render the results inconclusive, the interim results presented here suggest that the tactic of targeting PL warrants further study in a less-invasive manner.

Low glucose level and low pH alter the electrochemical function of human parietal pleura

The aim of the present study was to investigate whether low glucose and pH level, which are usually measured in complicated pleural effusions, alter the electrochemical function of healthy human parietal pleura. Parietal pleural pieces were stripped from 66 patients during thoracic surgery and were mounted in Ussing chambers. Krebs' solutions containing different glucose levels (0, 40 and 100 mg) and balanced at different pH levels (7.4, 7.3 and 7.2) were added to the pleural cavity surface of the pieces. Transmesothelial potential difference was measured at various time-points as an electrophysiological variable and transmesothelial resistance (R(TM)) was calculated using Ohm's law. When normal-glucose Krebs at pH 7.45 was used, R(TM) remained unchanged over time, but when low-glucose Krebs was used, R(TM) decreased. Krebs without glucose caused the greatest decrease in R(TM). Use of low-pH Krebs decreased R(TM). The lower the pH of the Krebs, the faster the decrease in R(TM) and the greater the effect. The decrease in R(TM) was greater with low-pH than with low-glucose Krebs. Low glucose and low pH caused an additive decrease in R(TM). Low glucose concentration and low pH cause alteration of the electrochemical function of human parietal pleura and could act as agents that lead to further exudate progression.

Potential role of ferritin heavy chain in oxidative stress and apoptosis in human mesothelial and mesothelioma cells: implications for asbestos-induced oncogenesis

Exposure to asbestos is a known etiological factor in malignant mesothelioma (MM). However, in vitro cell culture studies have provided paradoxical evidence that asbestos exposure to mesothelial cells causes cytotoxicity or apoptosis rather than malignant transformation. Although it has been shown that the iron associated with asbestos participates in the cell toxicity and probably MM pathogenesis via generation of reactive oxygen species (ROS), the molecular mechanisms largely remain unknown. Here, we demonstrate that ferritin heavy chain (FHC), a core subunit of iron-binding protein ferritin, works as an anti-apoptotic protein against toxic asbestos and oxidative stress in human mesothelial cells and MM cells. We found that FHC was induced in asbestos-exposed MeT-5A human mesothelial cells. The mesothelial cell line stably expressing FHC generated less amount of hydrogen peroxide (H2O2), one of the main ROS, after asbestos exposure and was more resistant to apoptosis induced by H2O2 compared with the cells transfected with the empty vector. Next, we investigated biological roles of FHC in human MM cell. We found that NCI-H2052, a human MM cell line, had a higher expression of endogenous FHC than MeT-5A and used the cell to address FHC function in MM. NCI-H2052 showed reduced H2O2 production and an apoptosis-resistant phenotype compared with MeT-5A. Suppression of the over-expressed FHC by using FHC small interfering RNA rendered the MM cells sensitive to apoptosis, suggesting the contribution of FHC to apoptosis resistance of the MM cells. Our findings highlight the potential role of FHC in the pathogenesis of asbestos-induced mesothelioma.

Local and systemic impacts of pleural oxygen exposure in thoracotomy

The pleural cavity is normally in a state of negative pressure and low oxygen tension. It is exposed to the atmosphere during thoracic surgery. However, no reports of pathophysiological investigation of the effects of pleural oxygen exposure involved in thoracotomy are available. In this study, the effects of pleural oxygen exposure on systemic and pleural inflammation were investigated. Male Wistar rats (9 weeks old) were placed on mechanical ventilation and underwent thoracotomy with lipopolysaccharide (LPS) administration, which simulates latent inflammatory condition. The pleural cavity was exposed to nitrogen (N(2) thoracotomy group), air (20% oxygen, air thoracotomy group), or 100% oxygen (O(2) thoracotomy group) under mechanical ventilation for 2 h. Animals were sacrificed 2 h or 8 h after LPS administration, and inflammatory indices (plasma tumor necrosis factor-alpha and interleukin-6, histology) were examined. For examination of inflammatory mediators, pleural effusion was added to cultured RAW264 cells, a murine macrophage cell line, and tumor necrosis factor-alpha levels in supernatant were measured. The capacity of pleural superoxide generation was investigated without LPS administration. Results showed increases in plasma interleukin-6 concentration and lung injury in the air and O(2) thoracotomy groups. Pleural oxygen exposure stimulated pleural superoxide generation, and increased pleural 4-hydroxy-2-nonenal and lung lipid peroxide concentrations. Tumor necrosis factor-alpha levels in cell culture supernatants were increased by the addition of pleural effusion from the air and O(2) thoracotomy groups. In conclusion, pleural oxygen exposure induced pleural oxidative injury and aggravated latent systemic inflammatory response.

Intrapleural activation, processing, efficacy, and duration of protection of single-chain urokinase in evolving tetracycline-induced pleural injury in rabbits

Intrapleural fibrinolysins have been used to treat pleural loculations. However, the efficacy of clinically available agents has recently been questioned, providing a rationale for investigation of new interventions. Single-chain urokinase plasminogen activator resists inhibition by serpins, and repeated, daily intrapleural administration of this agent prevents intrapleural loculation more effectively than complexes of this proenzyme with its receptor (Idell S, Mazar A, Cines D, Kuo A, Parry G, Gawlak S, Juarez J, Koenig K, Azghani A, Hadden W, McLarty J, Miller E. Am J Respir Crit Care Med 166: 920-926, 2002). Understanding of the protective mechanism and intrapleural processing remains unclear. We speculated that single-chain urokinase could induce sustained local fibrinolysis and protection by selective administration either before, during, or following loculation after pleural injury induced by tetracycline in rabbits. Enzymography, immunoassays, histology, immunohistochemistry, morphology, and morphometry were used to test the efficacy, duration of protective effect, and processing of single-chain urokinase. Intrapleural single chain urokinase prevented loculation at 72 h after injury (P < 0.01) if given either before or during adhesion formation and was converted to two-chain high-molecular-weight urokinase, which remained active for at least 24 h within pleural fluids. The effect was dose dependent, and established loculations at 72 h after tetracycline-induced injury were reversed at 96 h by single-dose treatment. Single-chain urokinase bound and saturated intrapleural plasminogen activator inhibitory (PAI)-1-like activity and urokinase-related immunoreactivity of the mesothelium was comparable in treatment or vehicle-control groups. Adhesions recurred by 2 wk after treatment with recurrence of excess local PAI activity. Single-chain urokinase induces sustained local fibrinolysis and reversibly prevents pleural loculation for up to 48 h after intrapleural administration after tetracycline-induced injury.

Store-mediated calcium entry in pleural mesothelial cells

Store-mediated Ca2+ entry is thought as the main pathway for Ca2+ influx in non-excitable cells. Although a role for the actin cytoskeleton in store-mediated Ca2+ entry has been proposed in some cell types, the role of actin cytoskeleton in store-mediated Ca2+ entry is still a controversy. To address this question, the effects of cytoskeletal modifiers on store-mediated Ca2+ entry in pleural mesothelial cells were examined. Thapsigargin (1 microM) induced a sufficient signal for the activation of store-mediated Ca2+ entry in pleural mesothelial cells. In the absence of extracellular Ca2+, thapsigargin induced only a transient elevation of [Ca2+]i. Moreover, re-addition of Ca2+ increased the elevation of [Ca2+]i. Passive elevations in [Ca2+]i without thapsigargin, which is induced from Ca2+ containing solution switch to Ca2+ free solution and re-add Ca2+ containing solution, were not observed in pleural mesothelial cells. Thapsigargin-induced Ca2+ entry was still present after nifedipine (1 microM) treatment. However, SKF96365 (1 microM) blocked thapsigargin-induced Ca2+ entry. Mycalolide B (1 microM) completely disrupts actin cytoskeleton in pleural mesothelial cells, but thapsigargin-induced store-mediated Ca2+ entry was preserved. Jasplakinolide (3 microM) prevented thapsigargin-induced store-mediated Ca2+ entry. These results suggest that store-mediated Ca2+ entry in pleural mesothelial cells may be mediated by a recently proposed secretion-like coupling model for store-mediated Ca2+ entry.

Effect of adrenaline on transmesothelial resistance of isolated sheep pleura

The effect of adrenaline on the transmesothelial resistance (RTM) of sheep's visceral and parietal pleura was studied using the Ussing chamber technique. Basal transmesothelial resistance of visceral pleura was found to be 20.71 +/- 0.31 Omega cm2, whereas that of parietal pleura was found to be 19.53 +/- 0.34 Omega cm2. Immediately after the addition of adrenaline (10(-7) M) both apically and basolaterally on the visceral and parietal pleura, these values were significantly increased (P < 0.05). Addition of the nonselective beta-receptor blocker, propranolol (10(-5) M), suppressed this effect in both visceral and parietal pleura, while addition of the nonselective alpha-receptor blocker, phentolamine (10(-5) M), partly suppressed the above-mentioned increase in the parietal pleura. In conclusion, our results show that adrenaline has a rapid effect on both pleurae. This rapid effect is mediated by the stimulation of beta-adrenergic receptors in the case of visceral pleura, while in the case of parietal pleura this effect seems to be due to a stimulation of alpha- and beta-adrenergic receptors. On the visceral pleura the effect of adrenaline vanishes after some minutes and on the parietal this effect is more permanent than the visceral's one, suggesting differences in the distribution of the adrenergic receptors between the visceral and parietal pleura.

mu-Opioid influence on transmesothelial resistance of isolated sheep pleura and parietal pericardium

The effect of morphine (mu-opioid receptor agonist) on the transmesothelial resistance (R(TM)) of sheep's pleura and parietal pericardium was studied using the Ussing chamber technique. Basal transmesothelial resistance of parietal pleura was found to be 19.57+/-0.32 Omega cm2 and of visceral pleura was found to be 19.41+/-0.31 Omega cm2, whereas that of parietal pericardium was found to be 22.83+/-0.4 Omega cm2. Immediately after the addition of morphine (10(-9) M) both apically and basolaterally on the parietal pleura and parietal pericardium, these values were significantly increased (P<0.05). On the contrary, addition of morphine (10(-9) M) resulted in a rapid increase, only when placed basolaterally on the visceral pleura (P<0.05). In conclusion, our findings suggest that morphine, probably through mu-opioid stimulation, increases in vitro the transmesothelial resistance of the parietal pleura, of the visceral pleura when added basolaterally and of the parietal pericardium.

[Effect of anti-vascular endothelial growth factor antibody on pleurodesis induced by transforming growth factor-beta or doxycycline in rabbits]

OBJECTIVE

The intrapleural injection of transforming growth factor-beta (TGF-beta) or doxycycline produces excellent pleurodesis in rabbit models. However, the intrapleural injection of these agents induces large pleural effusion which is possibly related to vascular endothelial growth factor (VEGF). This study investigated whether anti-VEGF antibody has any effect on the fluid production or the pleurodesis induced by TGF-beta or doxycycline in rabbits.

METHODS

Two groups of New Zealand white rabbits (7 each) were given TGF-beta 5.0 microg intrapleurally. The TGF-beta treatment group received anti-VEGF antibody 10 mg/kg intravenously 24 h before TGF-beta injection and the TGF-beta control group received no antibody. Another two groups of New Zealand white rabbits (7 each) were given doxycycline 10 mg/kg intrapleurally after chest tube placement. The doxycycline treatment group received 10 mg/kg anti-VEGF antibody intravenously 24 h before doxycycline injection and the doxycycline control group received no Anti-VEGF antibody. The rabbits were sacrificed at 2 weeks and the pleurodesis score was graded macroscopically on a 1-8 scale. The degree of angiogenesis in pleural tissues was assessed by immunohistochemical staining for factor VIII which was assessed by computer-assisted digital analysis.

RESULTS

The administration of anti-VEGF antibodies had no effect on pleural fluid volume or the characteristics of the fluid. The mean pleurodesis score of TGF-beta control group (7.7 +/- 0.8) was significantly (P < 0.05) higher than that of the antibody pre-treatment TGF-beta group (4.4 +/- 2.4). The mean pleurodesis score of the doxycycline control group (6.0 +/- 1.7) was significantly (P < 0.05) higher than that of the antibody pre-treatment doxycycline group (2.0 +/- 0.9). The administration of the anti-VEGF antibody also reduced the angiogenesis. The percentage of pleural tissue demonstrating angiogenesis in the TGF-beta control group (4.9 +/- 0.4)% was significantly (P < 0.05) higher than that of the antibody treatment TGF-beta group (2.9 +/- 0.7)%. The percentage of pleural angiogenesis in the doxycycline control group (6.9 +/- 2.2)% was significantly (P < 0.05) higher than the antibody pre-treatment doxycycline group (2.2 +/- 0.9)%.

CONCLUSIONS

Anti-VEGF antibody significantly inhibits the pleurodesis induced by doxycycline or TGF-beta. This observation suggests that VEGF and angiogenesis play a pivotal role in the production of pleurodesis.

Puqienine F, a Novel Veratramine Alkaloid from the Bulbs of Fritillaria puqiensis

A novel veratramine alkaloid, called puqienine F (1) and possessing a 12,16-epoxy ring, was isolated from the bulbs of Fritillaria puqiensis G. D. Yu et G. Y. Chen (Liliaceae). The structure was elucidated by extensive spectral and X-ray crystallographic analyses.

Pleurodesis is inhibited by anti-vascular endothelial growth factor antibody

STUDY OBJECTIVES

The intrapleural injection of transforming growth factor (TGF)-beta2 produces pleurodesis in rabbits associated with large pleural effusions. This study investigated whether anti-vascular endothelial growth factor (VEGF) antibody has any effect on the fluid production or the pleurodesis induced by TGF-beta2.

INTERVENTIONS AND MEASUREMENTS

Three groups of seven New Zealand white rabbits were administered TGF-beta2 5.0 microg intrapleurally. Two groups received anti-VEGF antibody (10 mg/kg and 25 mg/kg) IV 24 h before TGF-beta2 injection, and the third group received no antibody. The rabbits were killed at 2 weeks, and the macroscopic pleurodesis score was determined. The degree of pleural angiogenesis was assessed by immunohistochemical staining for factor VIII.

RESULTS

The administration of anti-VEGF antibodies had no significant effect on the pleural fluid volume or the characteristics of the fluid. The mean pleurodesis score of the seven rabbits in the control group (7.71 +/- 0.76) was significantly (p < 0.05) higher than that for seven rabbits in the low-dose treatment group (4.43 +/- 2.37) and the seven rabbits in the high-dose treatment group (4.57 +/- 2.36) [+/- ]. The percentage of pleural tissue demonstrating angiogenesis in the control group (4.87 +/- 0.43%) was significantly (p < 0.05) higher than that for the low-dose (2.94 +/- 0.68%) or high-dose (2.67 +/- 0.64%) antibody groups. When all rabbits were considered, there was a highly significant correlation between the pleural vascular density scores and the pleurodesis scores (r = 0.84, p < 0.01).

CONCLUSION

VEGF and angiogenesis appear to play a pivotal role in the production of a pleurodesis.

Penetration of clarithromycin in experimental pleural empyema model fluid

BACKGROUND

The degree of penetration of clarithromycin into the pleural fluid has not been studied.

OBJECTIVE

To determine the degree to which clarithromycin penetrates into empyemic pleural fluid using a new rabbit model of empyema.

METHODS

An empyema was created via the intrapleural injection of 1 ml turpentine followed 24 h later by instillation of 5 ml (10(10)) Escherichia coli bacteria (ATCC 35218) into the pleural space of New Zealand white rabbits. After an empyema was verified by thoracentesis and pleural fluid analysis, clarithromycin 30 mg/kg was administered intravenously. Antibiotic levels were determined on samples of pleural fluid and blood samples collected serially over 12 h. Antibiotic levels were estimated using HPLC.

RESULTS

The antibiotic penetrated well into the empyemic pleural fluid (AUC(PF)/AUC(serum) ratio of 1.57). The time to equilibration between the pleural fluid and blood antibiotic levels was 8 h. The peak pleural fluid level (Cmax(PF) of 2.88 microg/ml) occurred 1 h (Tmax(PF) of 1 h) after infusion and decreased thereafter. The Cmax(serum) was 3.53 microg/ml at 1 h after administration.

CONCLUSION

The levels of clarithromycin in the pleural fluid after intravenous administration are inhibitory for most of the usual pathogens causing empyema. The degree of penetration of clarithromycin should be considered when macrolides are selected for the treatment of patients with empyema.

Ultrastructural acute features of active remodeling after chemical pleurodesis induced by silver nitrate or talc

This study evaluated submicroscopic features of active pleural remodeling associated with chemical pleurodesis. Twenty seven rabbits received intrapleural injection of 0.5% silver nitrate (SN; N = 9) or 400 mg/kg talc slurry (N = 9) in 2 ml of saline solution; control rabbits (N = 9) received 2 ml of saline alone. The rabbits were sacrificed 15 minutes, 24 hours, or 7 days postinjection, and specimens of visceral pleura were obtained, fixed, and photographed for submicroscopic analysis. After 15 minutes of talc or SN exposure, prominent injury to the mesothelial cells and mesothelial cell-mesothelial basement membrane (MC-MBM) union was visible. There was focal remesothelialization of the denuded area through mesothelial cell migration, proliferation, and differentiation. After 24 hours, early wound healing, characterized by a superficial exudate, was evident where myofibroblasts had proliferated through a gap in the MC-MBM. After 7 days, proliferation of highly active myofibroblasts was observed; these cells produced abundant extracellular matrix components in a more organized distribution paralleling the surface. This third stage of remodeling was more evident with SN than talc-induced chemical pleurodesis. Our results suggest that ideal chemical pleurodesis results from injury to the MC-MBM union and abnormal wound healing, involving three essential steps: remesothelialization, fibroblastic proliferation, and extracellular matrix accumulation and remodeling.

Effect of diclofenac on experimental pleurodesis induced by tetracycline in rabbits

BACKGROUND AND OBJECTIVE

Pleurodesis is a frequently preferred procedure in thoracic surgery, and many factors may affect the process. We aimed to determine whether the administration of systemic diclofenac sodium diminishes the effectiveness of the pleurodesis induced by intrapleural tetracycline in rabbits.

METHODS

Twelve male New Zealand rabbits that received tetracycline 35 mg/kg intrapleurally were allocated into two groups. The first group (diclofenac group, n = 6) received 2 mg/kg diclofenac sodium intramuscularly for 10 days, and the second group (control group, n = 6) received acetaminophen 30 mg/kg orally for 10 days after the pleurodesis procedure. The rabbits were sacrificed after 28 days, and the pleural spaces were assessed grossly for evidence of pleurodesis and microscopically for evidence of fibrosis, inflammation, and collagenization.

RESULTS

The mean macroscopic pleurodesis score of the diclofenac group was 2.16 +/- 0.40 compared with 2.83 +/- 0.40 in the control group (p = .027). The mean microscopic pleurodesis score of the diclofenac group was 2. 3 +/- 1.03, whereas it was 3.5 +/- 0.54 in the control group (p = .045).

CONCLUSION

The administration of diclofenac sodium for 10 days following tetracycline pleurodesis reduces the effectiveness of pleurodesis in rabbits.

Pleuropulmonary fibrosis after long-term treatment with the dopamine agonist pergolide for Parkinson Disease

Dopamine agonists are increasingly used in the treatment of Parkinson disease, but they may cause serious adverse effects. In December 1983, symptoms of Parkinson disease developed in a 55-year-old man with no history of pulmonary disease, smoking, or asbestos exposure. He began treatment with dopamine agonists bromocriptine mesylate (in 1984) and pergolide mesylate (in 1989). In late 2000, pulmonary symptoms developed. Chest radiographs and computed tomographic findings showed a mass in the right upper lobe and effusion. A biopsy specimen showed pleural and parenchymal fibrosis. This syndrome resolved after cessation of pergolide therapy and a switch to pramipexole dihydrochloride. This case draws attention to the association of long-term ergot dopamine agonist therapy with pleuropulmonary fibrosis, which can develop as late as 11 years after the initiation of therapy. We also review evidence that the risk of this complication is substantially lower with the newer nonergot dopamine agonists.

Intrapleural Low-Dose Silver Nitrate Elicits More Pleural Inflammation and Less Systemic Inflammation Than Low-Dose Talc

STUDY OBJECTIVES

Several systemic effects have been described after talc pleurodesis. The aim of this study was to assess the systemic response induced by low, nonpleurodesis-inducing doses of talc and silver nitrate in an experimental model in rabbits.

DESIGN

Groups of six rabbits were injected intrapleurally with talc, 100 mg/kg or 400 mg/kg, and silver nitrate, 0.1% or 0.5%. After 6, 24, or 48 h, samples of blood and pleural fluid were collected and assayed for leukocytes, percentage of neutrophils, lactate dehydrogenase, interleukin-8, and vascular endothelial growth factor (VEGF) levels. Preinjection blood samples were used as normal blood controls.

MEASUREMENTS AND RESULTS

Silver nitrate 0.1% induced a more intense pleural inflammation than that produced by talc 100 mg/kg. In contrast, talc 100 mg/kg induced a more pronounced acute systemic response with higher values of WBCs and neutrophils, whereas silver nitrate 0.1% produced no significant increases in leukocytes or neutrophils. The serum interleukin-8 and VEGF levels increased in all groups, and decreased with time only in the silver nitrate 0.1% group. The highest serum VEGF levels were observed in the talc 100 mg/kg group.

CONCLUSIONS

In conclusion, 0.1% silver nitrate produced an intense pleural inflammatory response with a less evident systemic response in comparison to 0.5% silver nitrate and talc 100 mg/kg or 400 mg/kg.

Evaluating the prophylactic potential of the phtalimide derivative LASSBio 552 on allergen-evoked inflammation in rats

A previous study showed that the novel tetrazolephtalimide derivative LASSBio 552 (2-4-[3-(1H-1,2,3,4-tetraazol-5-yl)propoxy]phenethyl-1,3-isoindolinedione) prevents LTD(4)-evoked tracheal contraction. This led us to examine the putative anti-inflammatory effect of LASSBio 552 in comparison with the leukotriene CysLT(1) receptor antagonist zafirlukast using a model of allergic pleurisy in rats. Treatment with either LASSBio 552 (24-96 micromol/kg, i.p.) or zafirlukast (9-72 micromol/kg, i.p.), 1 h before challenge, inhibited eosinophil and mononuclear cell influx into the pleural cavity 24 h post-challenge, but failed to alter the increased levels of eotaxin, plasma leakage, mast cell degranulation and neutrophil infiltration noted 6 h post-challenge. CD4(+) T cell recruitment 24 h post-challenge was also sensitive to LASSBio 552. This treatment failed to alter cysteinyl leukotriene production at 6 h, but clearly inhibited the phenomenon 24 h and 48 h post-challenge. In in vitro settings LASSBio 552 inhibited allergen-evoked cysteinyl leukotriene generation from isolated mast cells, while histamine release remained unchanged. It also slightly inhibited cysteinyl leukotriene production by eosinophils and mononuclear cells triggered by Ca(+2) ionophore A23187. A leukotriene CysLT(1) receptor transfected cell-based assay revealed that LASSBio 552 did not prevent LTD(4)-evoked Ca(+2) influx, indicating that it was not a leukotriene CysLT(1) receptor antagonist. These findings indicate that LASSBio 552 is able to inhibit eosinophil influx triggered by allergen chalenge in a mechanism at least partially associated with suppression of CD4(+) T cell influx and cysteinyl leukotriene production.

Cell type-specific effects of asbestos on intracellular ROS levels, DNA oxidation and G1 cell cycle checkpoint

Exposure to asbestos fibers increases the risk of development of mesotheliomas and lung carcinomas, but not fibrosarcomas. We present data suggesting that resistance of fibroblasts to asbestos-induced carcinogenesis is likely to be connected with their lower ability to generate reactive oxygen species (ROS) in response to asbestos exposure and stricter control of proliferation of cells bearing asbestos/ROS-induced injuries. In fact, chrysotile (Mg6Si4O10(OH)8) asbestos exposure (5-10 microg/cm2) increased intracellular ROS and 8-oxo-guanine contents in rat pleural mesothelial cells, but not in lung fibroblasts. Simultaneously, moderate dosages of chrysotile and other agents increasing ROS levels (hydrogen peroxide, H2O2 and ethyl-methanesulfonate, EMS) inhibited cell cycle progression, in particular G1-to-S transition, in fibroblasts, but not in mesothelial cells. The arrested fibroblasts underwent cell death, while the majority of chrysotile-treated mesothelial cells survived. The differences in cell cycle response to asbestos/ROS-induced injuries correlated with distinct activity of p53-p21Cip1/Waf1 pathway in the two cell types. Chrysotile, H2O2 and EMS caused p53 upregulation in both cell types, but mesothelial cells, unlike fibroblasts, showed no accumulation of p21Cip1/Waf1. Of note, treatment with doxorubicin caused similar p53-dependent p21Cip1/Waf1 upregulation and cell cycle arrest in both cell types. This suggests differential response of fibroblasts and mesothelial cells specifically to asbestos/ROS exposure rather than to all DNA-damaging insults.

Increased levels of cyclic adenosine monophosphate contribute to the hyporesponsiveness of mast cells in alloxan diabetes

In this study, we investigated the influence of intracellular cyclic adenosine monophosphate (cAMP) changes on the rat mast cell hyporesponsiveness following immunological and non-immunological stimuli. Compared with mast cells from normal rats, those recovered from 21-day diabetic animals showed a significant augmentation in the intracellular levels of cAMP, in directly correlated with secretion of lower amounts of histamine after stimulation with antigen, bradykinin and compound 48/80 in vitro. Incubation of normal mast cells with selective inhibitors of phosphodiesterase type 4 (PDE 4) rolipram, NCS 613 and RP 73401, or the cell permeable analogue N6-2'-O-dibutyryladenosine 3':5'-cyclic monophosphate (db cAMP), led to a decrease of histamine secretion in vitro. However, the effectiveness of either NCS 613 or db cAMP in inhibiting antigen-induced degranulation is comparable in both normal and diabetic mast cells. We suggest that (a) there is a close correlation between higher levels of intracellular cAMP and hyporesponsiveness of diabetic mast cells, phenomena probably associated with a reduction in the expression and/or activity of PDE 4 and that (b) the mechanism of cAMP-mediated down-regulation of mast cell function is saturated in diabetic rats.