The perfused rat lung as a model for studies on the formation of surfactant and the effect of Ambroxol on this process

Co-aerosolized Pulmonary Surfactant and Ambroxol for COVID-19 ARDS Intervention: What Are We Waiting for?

After more than 225 days of the first reports of the novel coronavirus from China, COVID-19 pandemic is still on surge. The search for an effective and efficient therapeutic and pharmaceutical intervention is as important and urgent now as it was on Day 1. Majority of the efforts in this direction are toward finding small molecule interventions via repurposing or redirecting the therapeutic approaches. This hypothesis proposes a physical intervention approach directed toward rescuing the complex lung pathology observed in COVID-19 related acute respiratory distress syndrome (CARDS). The loss of content as well as the synthesis and turnover of the surfactant in ARDS has been termed as a "collateral damage." A synergistic, early stage, cost-effective, pharmaceutically viable, safe, and immediately available solution is hence required. The effectiveness of exogenous surfactant treatment in ARDS has been marred with several limitations as pointed out in various clinical trials and require revised protocols related to surfactant dose and mode of delivery. This hypothesis proposes aerosolized surfactant delivery taking the optimal dosing and coating costs into account along with co-delivery of ambroxol to provide synergistic benefits. Ambroxol is reported to have anti-inflammatory, -oxidant, -viral, and -bacterial activities and has a direct impact on the production and secretion of the surfactant from the alveolar Type 2 cells. If aerosolized, atomized, or nebulized in the form of ambroxol-loaded phospholipid nanovesicles at the early stages of ARDS, depleted surfactant levels may be reinstated and surfactant turnover can be initiated and maintained. The ability to deliver both the components in aerosolized-nebulized form may have a huge impact on alleviating the healthcare burden in low resource settings where the availability of ventilators is limited. In conclusion, the surfactant-ambroxol co-aerosolized intervention approach hypothesized here has implications reaching to clinical and pharmaceutical translation worldwide.

Safety of ambroxol in the treatment of airway diseases in adult patients

INTRODUCTION

Ambroxol is a widely used secretolytic and mucoactive over-the-counter agent primarily used to treat respiratory diseases associated with viscid mucus. Following post-marketing reports of hypersensitivity reactions and severe cutaneous adverse reactions (SCARs) possibly linked to ambroxol, the European Union's Pharmacovigilance Risk Assessment Committee (PRAC) initiated in April 2014 a review of the safety of ambroxol in all its registered indications, which was finalized in 2016. Areas covered: Here, we evaluate the clinical safety of ambroxol and provide an expert opinion on the benefit-risk balance of ambroxol in the treatment of adult patients with bronchopulmonary diseases. The evidence for this review is derived from clinical trials of ambroxol that were provided to the PRAC by the marketing authorization holders of ambroxol-containing medicines. Expert opinion: Clinical experience accumulated from randomized clinical trials and observational studies suggests that ambroxol is a safe and well-tolerated treatment of bronchopulmonary diseases, with a well-balanced and favorable benefit-risk profile. All reported adverse events were mild and self-limiting, and the risk of SCARs with ambroxol is low. Further investigations could address the safety and efficacy of ambroxol in pediatric lung diseases and in additional therapeutic indications, such as biofilm-dependent airway disease and lysosomal storage disorders.

Meta-analysis of high doses of ambroxol treatment for acute lung injury/acute respiratory distress syndrome based on randomized controlled trials

This study seeks to evaluate the potential benefits of high doses of ambroxol treatment for acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) by conducting a meta-analysis based on randomized controlled trials (RCTs). We searched the Pubmed, Embase, China National Knowledge Infrastructure, and Wanfang databases through December 2013. Only RCTs evaluating high doses of ambroxol (≥15 mg/kg or 1000 mg/day) treatment for patients with ALI/ARDS were selected. We included 10 RCTs involving 508 patients. Adjuvant treatment with high doses of ambroxol increased PaO(2)/FiO(2) (weight mean differences [WMD] = 69.18, 95% confidence intervals [CI]: 41.71-96.65), PO(2) (WMD = 11.74, 95% CI: 8.50-14.99), and SaO(2) (WMD = 2.15, 95% CI: 1.60-2.71) compared with usual treatment. Treatment with high doses of ambroxol appeared to reduce serum tumor necrosis factor-α level (WMD -7.92 µg/L; 95% CI, -10.94 to -4.9) and interleukin-6 level (WMD = -20.65 µg/L, 95% CI: -24.74 to -16.55) and to increase serum superoxide dismutase level (WMD = 19.07 NU/mL, 95% CI: 6.16-31.97). The findings suggest that treatment with high doses of ambroxol appears to improve PaO(2)/FiO(2), PO(2), and SaO(2), and the benefits might be related to ambroxol's anti-oxidant and anti-inflammatory properties.

Ambroxol lozenge bioavailability : an open-label, two-way crossover study of the comparative bioavailability of ambroxol lozenges and commercial tablets in healthy thai volunteers

OBJECTIVE

To compare the bioavailability of two 15mg ambroxol lozenges with a commercial 30mg ambroxol tablet.

DESIGN

Open-label, two-way crossover study.

METHOD

Each formulation was randomly administered to 20 healthy Thai volunteers (ten male and ten female) with a 1-week washout period between formulations. After administration, serial blood samples were collected over a 24-hour period and the plasma concentration of ambroxol was subsequently measured using high performance liquid chromatography with ultraviolet detection after liquid-liquid extraction. Pharmacokinetic parameters were analysed by a noncompartmental pharmacokinetic model and compared between formulations using analysis of variance with a significance level of 0.05.

RESULTS

The point estimates (90% CI) of the area under the plasma concentration-time curve (AUC) and peak plasma concentration (C(max)) ratios between lozenge and commercial tablet were 1.07 (0.89 to 1.28) and 1.20 (1.04 to 1.40), respectively. The point estimate (90% CI) of the difference between formulations for time to C(max) was 0.40 (-0.20 to 1.00).

CONCLUSION

The two formulations under test were not bioequivalent based on the stipulated bioequivalence criteria. The bioavailability from the ambroxol lozenge might be better, since the 90% CI of the AUC(0-infinity) fell outside the bioequivalence range, and its range was narrower. The difference in rate of absorption was not conclusive because ambroxol was delivered from the lozenge by two parallel processes, namely absorption via oral and gastrointestinal mucosa. The additional oral mucosal absorption might not only contribute more absorption but also introduce variability compared with that of tablet administration. The relative importance of oral versus gastrointestinal mucosal absorption of ambroxol from the lozenge formulation, and the clinical significance of this, requires further study.

The protective effects of Ambroxol in Pseudomonas aeruginosa-induced pneumonia in rats

INTRODUCTION

To evaluate the effect of Ambroxol on the pulmonary surfactant (PS) in rat pneumonia induced by Pseudomonas aeruginosa (PA).

MATERIAL AND METHODS

The pneumonic rats were obtained by injecting ATCC27853 intratracheally. One hundred and twenty SD rats were randomized into four groups: normal saline and Ambroxol was injected intraperitoneally following PA challenge in the PA/NS and PA/AM group; the other two groups were NS/AM and NS/NS. The wet/dry weight ratio (W/D), and pathological changes were assayed. Total proteins (TP), total phospholipid (TPL), and dipalmitoylphosphatidylcholine (DPPC) in bronchial alveolar lavage fluid (BALF) were analysed. Some BALF was cultured for colony counts. Ultrastructural change of the lung was observed by electron microscopy.

RESULTS

The W/D ratio in the PA/AM group was lower than that in the PA/NS group; both were higher than that in the NS/NS group (p < 0.05). There were more neutrophils in the PA/NS group than in the PA/AM group (p < 0.05), and more in the PA/AM group than in the NS/NS group (p < 0.05). The ratio of DSPC/TPL and DSPC/TP in the BALF in PA/NS group was lower than that in the PA/AM group; DSPC/TPL and DSPC/TP ratios also increased in the NS/AM group. The PA colony numbers in the PA/AM group were lower than in the PA/NS group (p > 0.05). In the PA/NS group, vacuolation occurred in the lamellar body of alveolar type 2 cells (AT2) and the PS layer was rough and broken in some areas. In the PA/AM group, the degree of vacuolation of the lamellar body was less than in the PA/NS group.

CONCLUSIONS

Ambroxol could protect rats from pneumonia by improving the level of endogenous PS, especially DPPC.

Distribution of intracellular and secreted surfactant during postnatal rat lung development

Pulmonary surfactant prevents alveolar collapse via reduction of surface tension. In contrast to human neonates, rats are born with saccular lungs. Therefore, rat lungs serve as a model for investigation of the surfactant system during postnatal alveolar formation. We hypothesized that this process is associated with characteristic structural and biochemical surfactant alterations. We aimed to discriminate changes related to alveolarization from those being either invariable or follow continuous patterns of postnatal changes. Secreted active (mainly tubular myelin (tm)) and inactive (unilamellar vesicles (ulv)) surfactant subtypes as well as intracellular surfactant (lamellar bodies (lb)) in type II pneumocytes (PNII) were quantified before (day (d) 1), during (d 7), at the end of alveolarization (d 14), and after completion of lung maturation (d 42) using electron microscopic methods supplemented by biochemical analyses (phospholipid quantification, immunoblotting for SP-A). Immunoelectron microscopy determined the localization of surfactant protein A (SP-A). (1) At d 1 secreted surfactant was increased relative to d 7-42 and then decreased significantly. (2) Air spaces of neonatal lungs comprised lower fractions of tm and increased ulv, which correlated with low SP-A concentrations in lung lavage fluid (LLF) and increased respiratory rates, respectively. (3) Alveolarization (d 7-14) was associated with decreasing PNII size although volume and sizes of Lb continuously increased. (4) The volume fractions of Lb correlated well with the pool sizes of phospholipids in lavaged lungs. Our study emphasizes differential patterns of developmental changes of the surfactant system relative to postnatal alveolarization.

Cell-specific modulation of surfactant proteins by ambroxol treatment

Ambroxol [trans-4-(2-amino-3,5-dibromobenzylamino)-cyclohexanole hydrochloride], a mucolytic agent, was postulated to provide surfactant stimulatory properties and was previously used to prevent surfactant deficiency. Currently, the underlying mechanisms are not exactly clear. Because surfactant homeostasis is regulated by surfactant-specific proteins (SP), we analyzed protein amount and mRNA expression in whole lung tissue, isolated type II pneumocytes and bronchoalveolar lavage of Sprague-Dawley rats treated with ambroxol i.p. (75 mg/kg body weight, twice a day [every 12 h]). The methods used included competitive polymerase chain reaction (RT-PCR), Northern blotting, Western immunoblotting, and immunohistochemistry. In isolated type II pneumocytes of ambroxol-treated animals, SP-C protein and mRNA content were increased, whereas SP-A, -B and -D protein, mRNA, and immunoreactivity remained unaffected. However, ambroxol treatment resulted in a significant increase of SP-B and in a decrease of SP-D in whole lung tissue with enhanced immunostaining for SP-B in Clara Cells. SP-A and SP-D were significantly decreased in BAL fluid of ambroxol-treated animals. The data suggest that surfactant protein expression is modulated in a cell-specific manner by ambroxol, as type II pneumocytes exhibited an increase in SP-C, whereas Clara cells exhibited an increase in the immunoreactivity for SP-B accounting for the increased SP-B content of whole lung tissue. The results indicate that ambroxol may exert its positive effects, observed in the treatment of diseases related to surfactant deficiency, via modulation of surfactant protein expression.

Mass Spectrometric Analysis of Surfactant Metabolism in Human Volunteers Using Deuteriated Choline

Surfactant reduces surface tension at pulmonary air-liquid interfaces. Although its major component is dipalmitoyl-phosphatidylcholine (PC16:0/16:0), other PC species, principally palmitoylmyristoyl-PC, palmitoylpalmitoleoyl-PC, and palmitoyloleoyl-PC, are integral components of surfactant. The composition and metabolism of PC species depend on pulmonary development, respiratory rate, and pathologic alterations, which have largely been investigated in animals using radiolabeled precursors. Recent advances in mass spectrometry and availability of precursors carrying stable isotopes make metabolic experiments in human subjects ethically feasible. We introduce a technique to quantify surfactant PC synthesis in vivo using deuteriated choline coupled with electrospray ionization tandem mass spectrometry. Endogenous PC from induced sputa of healthy volunteers comprised 54.0 +/- 1.5% PC16:0/16:0, 9.7 +/- 0.7% palmitoylmyristoyl-PC, 10.0 +/- 1.0% palmitoylpalmitoleoyl-PC, and 13.1 +/- 0.3% palmitoyloleoyl-PC. Infusion of deuteriated choline chloride (3.6 mg/kg body weight) over 3 hours resulted in linear incorporation into PC over 30 hours. After a plateau of 0.61 +/- 0.04% labeled PC between 30 and 48 hours, incorporation decreased to 0.30 +/- 0.02% within 7 days. Compared with native PC, fractional label was initially lower for PC16:0/16:0 (31.9 +/- 8.3%) but was higher for palmitoyloleoyl-PC (21.0 +/- 1.2%), and equilibrium was achieved after only 48 hours. We conclude that infusion of deuteriated choline and electrospray ionization tandem mass spectrometry is useful to investigate surfactant metabolism in humans in vivo.

Effect of twelve-months therapy with oral ambroxol in preventing exacerbations in patients with COPD. Double-blind, randomized, multicenter, placebo-controlled study (the AMETHIST Trial)

The objective of this prospective, randomized, double-blind, placebo-controlled, multicenter parallel-group study was to evaluate the effect of long-term ambroxol treatment in preventing exacerbations of chronic obstructive pulmonary disease (COPD). Two hundred and forty-two outpatients with COPD defined by ATS criteria with value of FEV1 between > or =60 and 80% of predicted and history of one or more exacerbations in the previous year were recruited by 26 Respiratory Medicine Centers in Italy and treated for 1 year with one ambroxol retard capsule of 75 mg twice daily or placebo. The percentage of patients free from exacerbation at 6 months was 63% with ambroxol and 60% with placebo (p=0.366) and at 12 months 56% with ambroxol and 53% with placebo (p=0.363). In a subset of 45 patients with more severe baseline symptoms, ambroxol therapy was associated with a significant higher percentage of patients free from exacerbation compared to placebo: 63 vs. 38% (p=0.038). In conclusion, we did not find a significant difference between long-term ambroxol therapy and placebo, in preventing exacerbations in patients with COPD. In patients with more severe respiratory symptoms at baseline, however, we observed a significant difference in the cumulative exacerbation-free persistence between ambroxol and placebo, suggesting that long-term muco-regulatory therapy with ambroxol could be useful in highly symptomatic patients with COPD.

Phosphatidylcholine metabolism of rat trachea in relation to lung parenchyma and surfactant

Pulmonary surfactant prevents alveolar collapse and contributes to airway patency by reducing surface tension. Although alveolar surfactant, consisting mainly of phospholipids (PL) together with neutral lipids and surfactant-specific proteins, originates from type II pneumocytes, the contribution of airway epithelia to the PL fraction of conductive airway surfactant is still debated. We, therefore, analyzed the composition, synthesis, and release of phosphatidylcholine (PC) molecular species as the main surfactant PL of the rat trachea compared with the lung. Analyses of individual PC molecular species with HPLC and electrospray ionization mass spectrometry revealed that the rat trachea contained and synthesized much more palmitoyloleoyl-PC, palmitoyllinoleoyl-PC, and palmitoylarachidonoyl-PC, together with increased amounts of alkylacyl-PC, and less surfactant-specific species such as dipalmitoyl-PC than the lung. Organ cultures with [methyl-3H]choline as precursor of PC revealed that, in the trachea, synthesized PC was retained in the tissue, rather than secreted. [Methyl-3H]choline-labeled dipalmitoyl-PC was a negligible component in the trachea, and, in contrast to the lungs, palmitoyloleoyl-PC was enriched in tracheal secretions. We conclude that the surfactant fraction in the airways does not originate from the airways but is produced in the alveolar space and transported upward.

YM-40461, a potent surfactant secretagogue, improves mucociliary clearance in SO2-exposed guinea pigs

The effects of the new pulmonary surfactant secretagogue YM-40461, 1-(2-dimethylaminoethyl)-1-(3,4,5-trimethoxyphenyl) urea, on tracheal mucociliary transport (MCT) were assessed using guinea pigs with acute bronchitis. Acute bronchitis was induced by SO2 gas exposure (400 ppm for 3 h). MCT velocity was measured by means of the dye gelatin technique. YM-40461 at doses of 1-10 mg/kg, p.o. induced recovery of MCT function, with an ED50 value of 2.4 mg/kg. Maximal recovery (78.0+/-12.5%) was observed 2 h in the animals treated with 10 mg/kg of YM-40461. Ambroxol and bromhexine showed less effect on the MCT dysfunction than YM-40461. An artificial surfactant (Surfacten) also aided recovery. YM-40461 at a dose of 10 mg/kg, p.o. significantly improved surfactant production without affecting mucus secretion. These results show that YM-40461 ameliorates MCT dysfunction caused by SO2 exposure by activation of pulmonary surfactant secretion.

Mucolytic and antitussive effects of erdosteine

To investigate the influence of erdosteine, a new homocysteine-derived expectorant, on airway clearance we studied the effects of the drug on the viscosity of mucin, on the mucociliary transport rate in quails, on airway secretion in rats and on the cough reflex in guinea-pigs. The active metabolite of erdosteine, M1 (10 microM to 1 mM), significantly reduced the viscosity of porcine stomach mucin. Erdosteine by itself did not reduce viscosity. Erdosteine significantly promoted mucociliary transport in quails and increased airway secretion in rats. The effect was still apparent 24h after administration. Erdosteine significantly suppressed citric acid-induced cough reflexes in guinea-pigs but did not suppress mechanical stimuli-induced cough reflexes. Erdosteine suppressed the reduction of the recovery volume of bronchoalveolar lavage fluid and albumin leakage into the fluid in citric acid-exposed guinea-pigs. These results indicate that erdosteine removes sputum by reducing its viscosity, and by promoting mucociliary transport and sustained enhancement of airway secretion. It also suppressed the chemical stimulation-induced cough reflex and plasma leakage into the airway. These results suggest that erdosteine is an excellent expectorant with several modes of action.

Chalcones, myo-inositol and other novel inhibitors of pulmonary carcinogenesis

The objective of the studies reported here has been to find novel chemopreventive agents effective against carcinogenesis of the lung. In particular, identification of suppressing agents, i.e., compounds preventing the evolution of the neoplastic process, has been sought. For this purpose, inhibition of pulmonary neoplasia in female A/J mice given the test agent starting one week after the last administration of three doses of benzo[a]pyrene has been employed as the experimental model. Under these conditions, chalcone, 4'-methoxychalcone,myo-inositol, dexamethasone, and "terpeneless" orange oil added to the diet suppressed pulmonary adenoma formation. Chalcone and 4'-methoxychalcone are open chain flavonoids, neither of these compounds occurs naturally, and their mechanism of action is not known. myo-Inositol is a naturally occurring compound of particular interest because of its exceedingly low toxicity. Dexamethasone is a potent glucocorticoid. Amongst its biological properties is the capacity to induce maturation of Type 2 alveolar cells and to stimulate production of surfactant by these cells. "Terpeneless" orange oil is a fraction of orange oil consisting predominantly of compounds with carbonyl or hydroxyl groups. The constituent or constituents responsible for the inhibitory effects observed is not known. The above studies are in an early phase of development and their ramifications remain to be determined.

beta-Adrenergic priming of rats in vivo modulates the effect of beta-agonist in vitro on surfactant phospholipid metabolism of isolated lungs

To evaluate the effects of multiple beta-adrenergic stimulations on pulmonary surfactant phospholipids, perfused lungs from beta-adrenergic primed and non-primed rats were challenged with the beta-agonist terbutaline in vitro. Cell-free lung lavage, lavagable alveolar cells and lung tissue were analysed for phospholipid content and incorporation of precursors. In lung lavage, terbutaline in vitro doubled the incorporation of 14C-choline and 3H-palmitate into total phosphatidylcholine (PC) and of 3H-palmitate into phosphatidylglycerol (PG). beta-adrenergic priming in vivo prior to terbutaline in vitro lowered the increase of precursor incorporation. For lavagable cells, terbutaline in vitro increased the incorporation of 3H-palmitate into PC. Priming in vivo reduced this effect and diminished the specific 3H-choline incorporation into lavagable cell PC below control level. For lung tissue, priming increased the amounts of PC and disaturated PC (DSPC) whereas terbutaline in vitro decreased DSPC in both primed and non-primed lungs. Terbutaline in vitro slightly increased the incorporation of 14C-choline and 3H-palmitate into PC and DSPC in non-primed but not in primed lungs. beta-adrenergic blockade by ICI 118.551 prevented all effects but generally increased 3H-palmitate incorporation into the phospholipids and, in lavagable cells, the amount of PC. We conclude that long-term beta-adrenergic treatment may alter the metabolism of pulmonary surfactant phospholipids by increasing tissue PC and DSPC and by decreasing the secretion of newly-synthesized PC.

A novel pharmacological approach for paraquat poisoning in rat and A549 cell line using ambroxol, a lung surfactant synthesis inducer

Paraquat (PQ) is a widely used herbicide that causes acute adult respiratory distress syndrome (ARDS) and chronic lung damage (diffuse fibrosis). One of the earliest biochemical effects induced by PQ is damage to type II pneumocytes with consequent depletion of surfactant. With the aim of counteracting the toxic effects of PQ, a series of investigations were performed into the possible protective effect of the drug ambroxol, which induces the synthesis of surfactant in lung alveolar type II cells. The number of survivors and survival time of rats treated ip with 35 mg PQ/kg was significantly increased by 3 days of ambroxol pretreatment and by ambroxol treatment 30 min or 2 hr after PQ. Total phospholipid content in lung and bronchoalveolar lavage fluid (BALF) was significantly reduced 30 hr after treatment with PQ alone. The association of ambroxol with PQ significantly antagonized this reduction. In BALF the ratio between palmitic acid and stearic acid concentrations was significantly lower in animals treated with PQ alone but was returned to normal by the association with ambroxol. The cell line A549, exposed in vitro to PQ concentrations from 0.5 x 10(-4) to 2 x 10(-3) M, showed a significant dose-dependent loss of viability. Cells pretreated with ambroxol (10 mg/ml) were more resistant to PQ and their viability started to decrease significantly only from a PQ concentration of 0.8 x 10(-3) M. Membrane microviscosity was measured on the same cells. Cells treated with PQ alone showed a reduction of membrane microviscosity, which was significantly counteracted by ambroxol pretreatment. The curves of modification of membrane microviscosity of cells treated with PQ and with ambroxol plus PQ paralleled those of cell viability, indicating that the stimulation of surfactant synthesis in vitro may be a prerequisite for counteracting some of the early effects of PQ.

Eprazinone alters lung lavage lipid levels and transtracheal ion transport

Eprazinone therapy improves pulmonary function and arterial pO2 in patients with chronic bronchitis; however, the mechanism of action is unknown. The purpose of this study was to determine if eprazinone alters either lung surfactant levels in bronchoalveolar lavage fluid (BAL) of normal rats, or ion transport across canine tracheal epithelium mounted in Ussing chambers. In the surfactant studies, normal rats were force fed three doses (50, 100, and 200 mg/kg) of eprazinone for 4 days. Eprazinone at a dose of 200 mg/kg significantly increased total and individual (with the exception of phosphatidylinositol) phospholipid levels and decreased total neutral lipids. Lower doses of eprazinone significantly decreased neutral lipid levels without affecting the phospholipids. There was no change in BAL levels of protein or cells and no abnormal histology. In airway epithelial studies, mucosal addition of eprazinone produced a dose-dependent partially reversible decrease in short-circuit current (Isc). The decrease in Isc at lower eprazinone concentrations was accounted for entirely by a decrease in net chloride secretion while at higher concentrations both sodium and chloride transport were affected. Submucosal eprazinone had no affect on ion transport. These studies suggest that eprazinone influences both BAL lipid levels and ion transport, either of which could lead to a beneficial therapeutic effect.

Lung injury induced by paraquat, hyperoxia and cobalt chloride: effects of ambroxol

The effects of the surfactant stimulating drug ambroxol were studied in rats given paraquat (PQ, 15 mg/kg, s.c.), intratracheal cobalt chloride (CoCl2, 2.5 or 1.25 mg Co/kg) or exposed for 2 days to oxygen (greater than 95% O2). Ambroxol (50 mg/kg, i.p., twice daily) was given as a pretreatment for 4 days, or up to 7 days following pneumotoxic administration. Besides body weight evolution and lethality, various pulmonary indices were measured 2 days (O2) or 3 days (PQ and CoCl2) and 7 days after pneumotoxic treatment: wet and dry lung weight, total cell count, distribution of inflammatory cells and lactate dehydrogenase in bronchoalveolar lavage fluid, and histological damage assessed by a semiquantitative injury score. Neither form of ambroxol treatment prevented the toxicity of any of the pneumotoxic agents. The use of a combination of different indices of lung damage showed that different pneumotoxic agents may cause quite distinctive patterns of injury.

Prevention by ambroxol of bronchopulmonary complications after upper abdominal surgery: double-blind Italian multicenter clinical study versus placebo

A double-blind multicenter study was carried out to evaluate the effectiveness of ambroxol, a drug able to promote surfactant synthesis, in the prevention of postoperative bronchopulmonary complications. A total of 252 patients with chronic obstructive lung disease (COLD) undergoing upper abdominal surgery were randomly allocated to receive either 1 g/day of ambroxol intravenously for 6 consecutive days in the perioperative period or placebo. Pulmonary complications were evaluated by clinical studies, radiographic, and blood gas analysis. There was a significant difference in atelectasis between the 2 groups (10.6% ambroxol vs 23.9% placebo). In addition, analysis of variance showed that the PaO2 values of the ambroxol-treated group after surgery decreased less than those of the placebo-treated group (p less than 0.05) from the preoperative values. The treatment was well tolerated, although nausea was significantly more frequent in the ambroxol-treated group. We think that ambroxol should be considered as an alternative and new pharmacologic approach for the prevention of postoperative pulmonary complications.

New concepts in molecular biology and ultrastructural pathology of the peritoneum: their significance for peritoneal dialysis

Continuous ambulatory peritoneal dialysis (CAPD) was developed into a life-maintaining therapy using a membrane whose fundamental biological characteristics were largely unknown. Recognition of this deficiency in our knowledge spurred a belated explosion of research that began with an exploration of the fine structure of the mesothelium. The monolayer of lining cells was found to be more sophisticated than previously imagined, being profusely carpeted with microvilli and bearing motile cilia, and in contrast to endothelium, was shown to possess a cytoplasm replete with organelles in which rough endoplasmic reticulum and lipid inclusions are prominent. Because these findings indicated possible secretory function, a link was sought between these observations and the discovery in effluent dialysate of phosphatidylcholine, a lubricant surfactant. Subsequently, comparison of mesothelial ultrastructure with that of type 2 pneumocytes revealed close concordance, while specialized fixation techniques developed for the preservation of lamellar bodies (the known storage vesicles of alveolar surfactant), when applied to mesothelium, for the first time revealed similar cytoplasmic inclusions. In vitro studies have shown that mesothelium, when incubated with radiolabeled precursor, is capable of synthesizing phosphatidylcholine, the principal constituent of pulmonary surfactant, in amounts similar to those produced by lung. The demonstration that the intensively studied type 2 pneumocyte and mesothelium both secrete lamellar bodies has opened up new possibilities in exploring the physiology, pharmacology, and pathology of the peritoneum. Recent work on mesothelial cell culture has shed new light on the factors involved in healing and regeneration. Recognition of the existence of subserosal multipotential cells and their importance in maintaining the integrity of the mesothelial cell layer is dawning. From the study of peritoneal biopsies in CAPD patients, evidence is accumulating that a process of nonenzymatic glycosylation of protein, similar to that which occurs in diabetes, is responsible for changes in stromal texture and the reduplication of basement membranes. Appreciation of stromal vulnerability to dialysate-induced accelerated aging following mesothelial loss may therefore require a new approach to peritoneal dialysis during peritonitis. Now that CAPD approaches clinical maturity there is increasing recognition of the need for strategies to ensure long-term preservation of the peritoneum as a dialyzing organ. Concomitantly there is a realization that these goals can only be attained through a much deeper appreciation of the molecular biology and pathology of the peritoneum itself.

Effect of ambroxol of neutrophil chemotaxis in vitro

Ambroxol hydrochloride has been shown to protect the lung from damage by polymorphonuclear leucocyte (PMN). In view of this observation we have studied the effect of Ambroxol on PMN chemotaxis using a variety of chemoattractants. The PMN response was inhibited 50-80% by preincubating the cells with concentrations of 10(-4) M Ambroxol. There was no evidence of PMN killing by the drug at concentration of 10(-3) M. The results suggest that Ambroxol my have a role in the management of patients whose chronic lung damage is due to excess PMN recruitment.

Pool sizes of precursors for phosphatidylcholine formation in adult rat lung type II cells

The pool sizes of the choline intermediates and cofactors involved in the CDPcholine pathway were studied in alveolar type II cells from adult rat lung. The choline phosphate pool was much larger than both the choline and CDPcholine pools. Kinetic analysis of the pool sizes revealed that cholinephosphate cytidylyltransferase catalyzes a non-equilibrium reaction. These results are consistent with the idea that cholinephosphate cytidylyltransferase regulates the choline flux into phosphatidylcholine in adult rat lung type II cells.