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Growth characteristics surrounding halophilic archaeal organisms are extremely limited in the scientific literature, with studies tending toward observing changes in cellular generation times under growth conditions limited to changes in temperature and sodium chloride concentrations. Currently, knowledge of the ionic stress experienced by haloarchaeal species through an excess or depletion of other required ions is lacking at best. The halophilic archaeon, Haloarcula marismortui, was analyzed under extreme ionic stress conditions with a specific focus on induced potassium ion stress using growth curves and analysis of the intracellular ion concentrations. Generation times were determined under potassium chloride concentrations ranging from 8 to 720 mM, and also in the presence of the alternative monovalent cations of lithium, rubidium, and cesium under limiting potassium conditions. Intracellular ion concentrations, as determined by inductively coupled mass spectrometry (ICP-MS), indicate a minimum intracellular total ion requirement of 1.13 M while tolerating up to 2.43 M intracellular concentrations. The presence of intracellular rubidium and cesium indicates that monovalent ion transport is important for energy production. Comparison of eight archaeal genomes indicates an increased diversity of potassium transport complex subunits in the halophilic organisms. Analysis of the generation times, intracellular concentrations and genome survey shows Har. marismortui exhibits an ability to cope with monovalent cation concentration changes in its native environment and provides insight into the organisms ion transport capability and specificity.

Inhaled adenosine 5'-monophosphate (AMP) has an "indirect" bronchoconstrictive effect through mast cell degranulation and mediator release, whereas inhaled histamine has a "direct" effect on smooth muscle. Prolonged treatment with inhaled glucocorticosteroids attenuates airway responsiveness (AR) to AMP and histamine. We investigated the early effects of inhaled fluticasone propionate (FP) therapy on AR in 3 consecutive double-blind, randomized, placebo-controlled crossover studies in steroid-naive subjects with mild asthma. In one study, each of 12 subjects received FP 1000 microg or matched placebo for 7 inhalations at 12 hourly intervals; AR to AMP and FEV(1) were measured 2 hours after the 3rd and 7th inhalations. In a second study, each of 12 subjects received FP 100, 250, or 1000 microg or matched placebo for 3 inhalations at 12 hourly intervals; AR to AMP and FEV(1) were measured 2 hours after the 1st and 3rd inhalations. In a third study, each of 8 subjects received a single inhalation of FP 1000 microg or matched placebo; AR to histamine was measured 2 hours later. In the first study, FP 1000 microg significantly attenuated AR to AMP by 2.7 and 2.5 doubling doses after 3 and 7 inhalations, respectively (P < or =.0001). In the second study, FP 100, 250, and 1000 microg significantly attenuated AR to AMP by 1.9, 2.2, and 2.7 doubling doses, respectively, after 1 inhalation and by 2.4, 2.2, and 3.2 doubling doses, respectively, after 3 inhalations (P < or =.0001); a small but significant increase in FEV(1) (>0.15 L) was observed after 3 inhalations but not after 1 inhalation of FP irrespective of dose (P < or =.05). In the third study, a single inhalation of FP 1000 microg had no effect on AR to histamine. We have demonstrated a reduction in AR to AMP but not AR to histamine within 2 hours of a single inhalation of FP. This reflects a rapid, topical anti-inflammatory action of inhaled FP by a mechanism of action that remains unknown.

Background: Cysteinyl leukotrienes (cysteinyl-LTs) have been implicated in the pathogenesis of allergen induced airway responses. Airway responsiveness (AR) to inhaled cysteinyl-LTs is dramatically increased following allergen challenge in animal studies. The effect in man has not been evaluated., Methods: Ten mild steroid-naïve asthmatic subjects with an isolated early asthmatic response (EAR) and 21 with an additional late asthmatic response (LAR) took part in a randomised controlled crossover study to assess AR to inhaled methacholine (MCh) and cysteinyl-LT D(4) (LTD(4)) 22 and 24 hours, respectively, after allergen challenge. Eight subjects had two further LTD(4) challenges separated by a 2 week washout period to assess the reproducibility of inhaled LTD(4) challenge., Results: In subjects with an isolated EAR, non-significant mean (SE) increases in AR of 0.4 (0.4) doubling doses (DD) for MCh and 0.4 (0.5) DD for LTD(4) followed allergen challenge compared with control. A significant correlation between AR to MCh and LTD(4) followed both control (r=0.91, 95% CI 0.67 to 0.98; p=0.0002) and allergen challenge (r=0.79, 95% CI 0.32 to 0.95; p=0.0063). In subjects with an additional LAR there was a significant increase in AR to MCh (1.2 (0.3) DD, p=0.0005) following allergen challenge but no overall effect on AR to LTD(4) (0.69 (0.4) DD, p=0.11). A significant correlation between AR to MCh and LTD(4) was again observed (r=0.70; 95% CI 0.38 to 0.87; p=0.0004) following control, although it was reduced following allergen challenge (r=0.48; 95% CI 0.063 to 0.76; p=0.027). LTD(4) challenge was highly reproducible with a mean difference of 0.2 (0.3) DD between challenges., Conclusions: Allergen challenge significantly increases AR to inhaled MCh but not to LTD(4) in subjects with LAR. The lack of a comparable increase in AR to LTD(4) is surprising. Endogenous cysteinyl-LTs are produced in abundance following allergen challenge and may enhance AR to MCh or induce a degree of tachyphylaxis to LTD(4).

Inhaled short-acting beta2-agonists provide greater protection against airway responsiveness (AR) to the mast-cell stimulus, adenosine 5'-monophosphate (AMP), than to histamine, a direct spasmogen. Both terbutaline and albuterol exhibit this mast-cell stabilizing property in a dose-dependent manner. A single dose of the long-acting beta2-agonist formoterol has also been reported to have a mast cell-stabilizing effect, whereas salmeterol has not. To explore the dose-related actions of the long-acting beta2-agonist formoterol on AR, the authors compared the acute effects of three doses of formoterol and terbutaline on AR to AMP and histamine. In a double-blind, randomized, placebo-controlled, cross-over study, 25 mild, steroid naive, asthmatic subjects attended on 10 occasions. At each visit, subjects inhaled either a single dose of terbutaline (500 microg), formoterol (6, 12 or 24 microg) or a matched placebo, administered via Turbuhaler, 30 min prior to challenge with both AMP and histamine. Each dose of beta2-agonist reduced AR to AMP and histamine. The bronchoprotective effects of formoterol (6 microg) and terbutaline (500 microg) were similar in magnitude in reducing AR to histamine (mean +/- SD: 3.6 +/- 0.3 and 3.1 +/- 0.3 doubling doses (DD)) and AR to AMP (3.5 +/- 0.5 and 3.3 +/- 0.4 DD, respectively). Overall, formoterol reduced AR to both spasmogens in a dose-dependent manner. In addition, formoterol (12 and 24 microg) provided a significantly greater protective effect against AMP than against histamine challenge. It decreased AR by 5.7 +/- 0.6 and 6.3 +/- 0.7 DD against AMP and 4.3 +/- 0.4 and 4.8 +/- 0.43 DD against histamine, respectively. The results of this study indirectly demonstrated an in vivo dose-dependent mast-cell stabilizing effect of formoterol, in addition to functional antagonism on airway smooth muscle. This property of beta2-agonists may have clinical benefits in asthma management.

Background: Interferon beta treatment is only partially effective in multiple sclerosis (MS) suggesting a potential role for adjunctive therapies. Retinoids can augment the clinical efficacy of type 1 interferons in patients with cancer. We reasoned that the same might hold in MS. Interferon beta-1b added to peripheral blood mononuclear cells in vitro partially reverses the CD8 suppressor cell defect of patients with MS. All-trans retinoic acid added to peripheral blood mononuclear cells from untreated patients with MS or from controls potentiates this ability of interferon beta-1b to augment CD8 suppressor cell function in vitro., Objective: To determine whether retinoid administration to patients with MS who are being treated with interferon beta-1b augments their CD8 suppressor cell function., Setting: A university hospital MS clinic., Participants: Patients with MS who were being treated with interferon beta-1b, 14 patients with secondary progressive MS and 3 patients with relapsing remitting MS., Results: Seventeen patients with MS received etretinate treatment for up to 6 months. Planned dosing was 10 mg 3 times daily for the first month, 25 mg twice daily for the second and third months, and 10 mg twice daily thereafter. The 25-mg twice daily dose was not well tolerated and of the 14 patients who remained in the phase 1 clinical trial through month 3 dose reduction to 10 mg thrice daily was required in 1 patient and to 10 mg twice daily in 4 patients. Eleven patients completed the trial. Etretinate treatment significantly augmented suppressor function over baseline values at 1, 3, and 6 months. No meaningful change was noted in disability or quality of life over the course of the phase 1 clinical trial. Neuropsychological testing of completers suggested improvement on selected aspects of verbal memory at 6 months compared with baseline values., Conclusions: Etretinate treatment at a dose of 10 mg twice or three times daily augments suppressor cell function in patients with MS receiving interferon beta-1b. Higher dose etretinate treatment (25 mg twice daily) is poorly tolerated by patients with MS. Even at 10 mg twice daily adverse experiences involving the mucous membranes and the skin become troublesome for some, but not all, patients. Whether pulse therapy or administration of retinoid restricted to the day of interferon beta dosing will also augment suppressor function, while being better tolerated, remains to be determined.

1. The aim of the present study was to investigate the role of adenosine A2b receptors in the anti-proliferative action of theophylline in human peripheral blood mononuclear cells (HPBMC) from healthy and asthmatic subjects. 2. Theophylline significantly inhibited PHA-induced proliferation of HPBMC from both healthy and asthmatic donors but only at relatively high concentrations at 1 mM (P<0.05). Enprophylline, a drug which also acts as a non-selective phosphodiesterase (PDE) inhibitor and is a selective A2b receptor antagonist, had no significant effect on proliferation of cells from either group at concentrations up to 10 microM (P>0.05; n=6). 3. Adenosine deaminase (2 u ml(-1)), which metabolizes adenosine, had no significant effect on PHA-induced HPBMC proliferation over a range of concentrations (0 - 8 microg ml(-1)) in cells from either healthy or asthmatic subjects. 4. The adenosine receptor agonists N(6)-cyclopentyladenosine (CPA, A1-selective) and 5'-N-ethylcarboxamidoadenosine (NECA, A1/A2) produced a small but significant inhibition of PHA-induced proliferation of HPBMC from healthy and asthmatic subjects (10 microM, P<0.05; n=6). In contrast, 5'-N-ethylcarboxamido-2-[4-(2-]carboxyethyl)phenethyl]adenosine (CGS21680, A2a-selective) was without significant effect (P>0.05; n=6). 5. The adenosine receptor antagonist alloxazine (A2b-selective) had no significant effect, while 8(3-chlorostyryl)caffeine,(CSC, A2a-selective) significantly inhibited PHA-induced proliferation of HPBMC from both groups (P<0.05; n=6). 6. Our results suggest that endogenous or exogenous adenosine has little effect on the proliferation of HPBMC obtained from healthy or asthmatic subjects. Thus it would appear that the effect of high concentrations of theophylline is not related to adenosine receptor antagonism.

Inhaled corticosteroids decrease airway responsiveness in asthma partly through suppression of airway inflammation. We have previously demonstrated that inhaled budesonide reduced airway responsiveness to the mast cell stimulus adenosine-5'-monophosphate (AMP) to a threefold greater extent than to methacholine and sodium metabisulfite, suggesting that AMP responsiveness may be a more sensitive marker of airway inflammation and steroid action in order to assess a dose-response relationship. To investigate this, we studied the effects of three doses of the novel corticosteroid ciclesonide (50 micrograms, 200 micrograms, and 800 micrograms) inhaled as a dry powder twice daily on airway responsiveness to AMP and inflammatory parameters in induced sputum. In a three-parallel-dose group, double-blind, placebo-controlled, randomized, crossover study, with a washout period of 3 to 8 wk, a total of 29 patients with mild to moderate allergic asthma underwent AMP challenge and sputum induction before and after 14 d of treatment with ciclesonide or matched placebo. Compared with placebo, ciclesonide 100 micrograms, 400 micrograms, and 1,600 micrograms daily reduced airway responsiveness to AMP by 1.6 (95% confidence interval [CI], -0.1 to 3.4, not significant [NS]), 2.0 (95% CI, 0.4 to 3.6, p < 0.05), and 3.4 (95% CI, 2.3 to 4. 4, p < 0.05) doubling doses, respectively, and this reduction in airway responsiveness was dose-dependent (p = 0.039). A significant reduction in the percentage of eosinophils in induced sputum was observed after 400 micrograms and 1,600 micrograms daily ciclesonide (p < 0. 05), but this was not dose-dependent. Sputum eosinophil cationic protein (ECP) was significantly reduced after 400 micrograms daily ciclesonide only (p < 0.05). Thus, in patients with mild to moderate asthma, assessment of airway responsiveness to AMP, rather than inflammatory parameters in induced sputum, represents a sensitive method to evaluate a dose-response relationship of an inhaled corticosteroid and may have applications in evaluating other novel inhaled corticosteroids.

Short-acting beta(2)-agonists provide greater protection to bronchoconstriction induced by adenosine-5'-monophosphate (AMP) than does methacholine. Because AMP produces bronchoconstriction through release of mediators from mast cells, and methacholine directly constricts airway smooth muscle, this suggests that beta(2)-agonists stabilize mast cells in vivo. This in vivo property has not been demonstrated with long-acting beta(2)-agonists. We undertook two double-blind, randomized, crossover, placebo-controlled studies to investigate the effects of salmeterol and albuterol on airway responsiveness (AR) to AMP and histamine in patients with mild asthma. In the first study, 19 patients attended on four occasions to inhale salmeterol 50 micrograms or placebo 2 h before challenge with AMP or histamine. In the second study 16 patients (13 of whom had participated in the first study) were studied in a similar fashion but inhaled albuterol 400 micrograms or placebo 30 min prior to challenge. Salmeterol reduced AR to AMP and histamine by 3.4 +/- 0.3 and 3.9 +/- 0.3 doubling doses, respectively (NS). In contrast, albuterol demonstrated a greater protective effect on AMP than on histamine, reducing AR by 5.1 +/- 0.3 and 3.8 +/- 0.2 doubling doses, respectively (p < 0.005). Thus, in contrast to albuterol, salmeterol did not demonstrate mast-cell stabilizing properties in vivo at a time corresponding to maximal bronchodilatation. These findings might be explained by the unique pharmacologic profile of salmeterol in combination with the differential beta(2)-adrenoceptor pharmacology of bronchial mast cells and bronchial smooth muscle.