Hyperosmolarity of the airway surface liquid (ASL) has been proposed as the stimulus for hyperpnoea-induced asthma. We found previously that mucociliary clearance (MCC) was increased after isocapnic hyperventilation (ISH) with dry air, and we proposed that the increase related to transient hyperosmolarity of the ASL. We investigated the effect of increasing the osmolarity of the ASL on MCC, by administering an aerosol of concentrated salt solution.MCC was measured using 99m Tc-sulphur colloid, gamma camera and computer analysis in 12 asthmatic and 10 healthy subjects on three separate days, involving administration of each of the following: 1) ultrasonically nebulized 14.4% saline; 2) ultrasonically nebulized 0.9% saline; and 3) no aerosol intervention (control).The (mean±SD) volume of nebulized 14.4% saline was 2.2±1.2 mL for asthmatics and 3.2±0.7 mL for healthy subjects. This volume was delivered over a period of 5.4±1.3 and 6.4±0.7 min for asthmatic and healthy subjects, respectively. The airway response to 14.4% saline was assessed on a separate visit and the fall in forced expiratory volume in one second (FEV1) was 22±4% in the asthmatic and 3±2% in the healthy subjects. Compared to the MCC with the 0.9% saline and control, the hypertonic aerosol increased MCC in both groups. In asthmatic subjects, MCC of the whole right lung in 1 h was 68±10% with 14.4% saline vs 44±14% with 0.9% saline and 39±13% with control. In healthy subjects, MCC of the whole right lung in 1 h was 53±12% with 14.4% saline vs 41±15% with 0.9% saline and 36±13% with control.We conclude that an increase in osmolarity of the airway surface liquid increases mucociliary clearance both in asthmatic and healthy subjects. These findings are in keeping with our previous suggestion that the increase in mucociliary clearance after isotonic hyperventilation with dry air is due to a transient hyperosmolarity of the airway surface liquid. Eur Respir J., 1996, 9, 725- We have previously found that mucociliary clearance (MCC) increases immediately after hyperventilation with dry air both in asthmatic and healthy subjects [1] at the time that asthmatic subjects develop airway narrowing. Although the mechanism for this increase is unknown, we postulated that the increase in MCC after hyperventilation with dry air is due to a transient hyperosmolarity of the airway surface liquid [1]. It is possible that the increase in MCC and the bronchoconstriction that follows hyperventilation with dry air share a common mechanism.Inhalation of hypertonic saline aerosol (7%) has been shown to increase mucociliary clearance in patients with bronchitis [2] and cystic fibrosis [3] who have impaired baseline mucociliary clearance. Although, these studies suggest that hypertonic saline stimulates the mucociliary system, there are no reported studies of the effect of hypertonic saline on the MCC in asthmatic and healthy subjects with normal baseline mucociliary clearance.The aim of the present study was to investigate the effect of a hyperosmolar stimulus on MC...

Using human peripheral blood mononuclear cells as osteoclast precursors, we showed that dexamethasone stimulated osteoclast generation at a pharmacological concentration but did not affect the life span of human osteoclasts. Dexamethasone also dose-dependently increased signals for osteoclastogenesis.Introduction: Glucocorticoid-induced osteoporosis is a common and serious disease. Glucocorticoids predominantly affect osteoblast proliferation and life span. Much of the bone loss is caused by reduced bone formation, but there is also an element of increased bone resorption. Materials and Methods: Human peripheral blood mononuclear cells were cultured on whale dentine and induced to differentiate to osteoclasts by RANKL and human macrophage-colony stimulating factor (M-CSF). Osteoclast activity was quantified by pit area. RANKL and osteoprotegerin (OPG) expression in osteoblasts were measured by real-time RT-PCR. Results: In the early phase of osteoclast generation (0-16 days), cultures from two different donors showed that dexamethasone at 10 −8 M increased pit area by 2.5-fold, whereas lower concentrations had no effect. At the highest dexamethasone concentration (10 −7 M), pit area was reduced. In 21-day cultures from three other donors, a similar increase was seen with dexamethasone at 10 −8 M. There was, however, no evidence of increased life span of osteoclasts with dexamethasone. In human primary osteoblasts, dexamethasone dosedependently reduced OPG and increased RANKL expression as measured by quantitative real time RT-PCR. Conclusion: These data provide some explanation at a cellular and molecular level for the observed increase in bone resorption seen in patients treated with glucocorticoids and indicate that there are clear direct effects of glucocorticoids on bone resorption in human cell systems that may differ from other species.

The mechanisms of insulin resistance in the obese Zucker rat have not been clearly established but increased diacylglycerol-protein kinase C (DAG-PKC) signalling has been associated with decreased glucose utilisation in states of insulin resistance and non-insulin-dependent diabetes mellitus. The purpose of this study was to characterise tissue-and isoform-selective differences in DAG-PKC signalling in insulin-sensitive tissues from obese Zucker rats, and to assess the effects of feeding on DAG-PKC pathways. Groups of male obese (fa/fa, n=24) and lean (fa/-, n=24) Zucker rats were studied after baseline measurements of fasting serum glucose, triglycerides, insulin and oral glucose tolerance tests. Liver, epididymal fat and soleus muscle samples were obtained from fed and overnight-fasted rats for measurements of DAG, PKC activity and individual PKC isoforms in cytosol and membrane fractions. Obese rats were heavier (488 7 vs 315 9 g) with fasting hyperglycaemia (10·5 0·8 vs 7·7 0·1 mM) and hyperinsulinaemia (7167 363 vs 251 62 pM) relative to lean controls. In fasted rats, PKC activity in the membrane fraction of liver was significantly higher in the obese group (174 16 vs 108 12 pmol/ min/mg protein, P<0·05) but there were no differences in muscle and fat. The fed state was associated with increased DAG levels and threefold higher PKC activity in muscle tissue of obese rats, and increased expression of the major muscle isoforms, PKC-and PKC-: e.g. PKC activity in the membrane fraction of muscle from obese animals was 283 42 (fed) vs 107 20 pmol/min/mg protein (fasting) compared with 197 27 (fed) and 154 21 pmol/ min/mg protein (fasting) in lean rats. In conclusion, hepatic PKC activity is higher in obese rats under basal fasting conditions and feeding-induced activation of DAG-PKC signalling occurs selectively in muscle of obese (fa/fa) rats due to increased DAG-mediated activation and/or synthesis of PKC-and PKC-. These changes in PKC are likely to exacerbate the hyperglycaemia and hypertriglyceridaemia associated with obesity-induced diabetes.

Mannitol inhalation increases urinary excretion of 9alpha,11beta-prostaglandin F2 (a metabolite of prostaglandin D2 and marker of mast cell activation) and leukotriene E4. The present study tested the hypothesis that beta2-adrenoreceptor agonists and disodium cromoglycate (SCG) protect against mannitol-induced bronchoconstriction by inhibition of mast cell mediator release. Fourteen asthmatic subjects inhaled mannitol (mean dose 252+/-213 mg) in order to induce a fall in forced expiratory volume in one second (FEV1) of > or = 25%. The same dose was given 15 min after inhalation of formoterol fumarate (24 microg), SCG (40 mg) or placebo. Pre- and post-challenge urine samples were analysed by enzyme immunoassay for 9alpha,11beta-prostaglandin F2 and leukotriene E4. The maximum fall in FEV1 of 32+/-10% on placebo was reduced by 95% following formoterol and 63% following SCG. Following placebo, there was an increase in median urinary 9alpha,11beta-prostaglandin F2 concentration from 61 to 92 ng.mmol creatinine(-1), but no significant increase in 9alpha,11beta-prostaglandin F2 concentration in the presence of either formoterol (69 versus 67 ng.mmol creatinine(-1)) or SCG (66 versus 60 ng.mmol creatinine(-1)). The increase in urinary leukotriene E4 following placebo (from 19 to 31 ng.mmol creatinine(-1)) was unaffected by the drugs. These results support the hypothesis that the drug effect on airway response to mannitol is due to inhibition of mast cell prostaglandin D2 release.

We studied, separately, the effects of the histamine antagonist, fexofenadine hydrochloride, and the leukotriene antagonist, montelukast sodium, and their placebos on airway sensitivity to and recovery from inhaled mannitol in subjects with asthma. Two 180-mg doses of fexofenadine were taken over 14 h, and three 10-mg doses of montelukast over 36 h, with the last dose 5 h before challenge. Fexofenadine reduced sensitivity to mannitol and the PD(15) was (mean [95% confidence interval] 138 [95, 201]) mg versus placebo (51 [25, 106] mg) (p < 0.001). The final percent reduction in FEV(1) with fexofenadine was 20.8 +/- 5.4% and not different from placebo (20.1 +/- 5.3%) (p = 0.7); however, recovery was slower with fexofenadine compared with placebo (p < 0.001). By contrast, montelukast had no effect on sensitivity to mannitol and the PD(15) was 71 [36, 144] mg versus placebo (87 [51, 148] mg (p = 0.35). The total dose of mannitol delivered and the final percent reduction in FEV(1) with montelukast were 171 +/- 142 mg and 21 +/- 4% and for placebo were 182 +/- 144 mg and 20 +/- 5% (p = 0.35, p = 0.59, respectively). However, recovery of FEV(1) to baseline was faster with montelukast, with the area under the percent reduction FEV(1)-versus-time curve reduced (220 +/- 121% change.min) compared with placebo (513 +/- 182% change.min) (p < 0.001). We conclude that whereas histamine is important for the initial airway response, leukotrienes are important in sustaining the airway response to inhaled mannitol.