Mechanisms of glucocorticosteroid action in bronchial asthma

New Ideas in Allergen-Specific Immunotherapy

Immunotherapy represents the only allergen-specific treatment of allergic diseases. The clinical efficacy has been documented in a number of studies involving both rhinitis and asthma patients, although because of the multifactorial pathophysiology including hyperresponsiveness, asthma may not respond as satisfactorily as rhinitis. Owing to the capacity to reduce the release of allergic mediators and thereby the allergic inflammation, immunotherapy has advantages over the nonspecific drug treatment primarily interfering at the target level of mediators. The clinical efficacy may be improved and the risk of side effects reduced by the use of modified allergens or by immunological manipulation in parallel with allergen administration.

Allergic bronchopulmonary aspergillosis in patients with cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a pulmonary disorder that often occurs in patients with asthma or cystic fibrosis (CF) and is characterized by a hypersensitivity response to the allergens of the fungus Aspergillus fumigatus. In patients with CF, growth of A. fumigatus hyphae within the bronchial lumen triggers an immunoglobulin E (IgE)-mediated hypersensitivity response that results in airway inflammation, bronchospasm, and bronchiectasis. In most published studies, the prevalence of ABPA is about 8.9% in patients with CF. Since the clinical features of this condition overlap significantly with that of CF, ABPA is challenging to diagnose and remains underdiagnosed in many patients. Diagnosis of ABPA in CF patients should be sought in those with evidence of clinical and radiologic deterioration that is not attributable to another etiology, a markedly elevated total serum IgE level (while off steroid therapy) and evidence of A. fumigatus sensitization. Management of ABPA involves the use of systemic steroids to reduce inflammation and modulate the immune response. In patients who do not respond to steroids or cannot tolerate them, antifungal agents should be used to reduce the burden of A. fumigatus allergens. Recent studies suggest that omalizumab may be an effective option to reduce the frequency of ABPA exacerbations in patients with CF. Further randomized controlled trials are needed to better establish the efficacy of omalizumab in managing patients with CF and ABPA.

Exploration of the Hypothalamic-Pituitary-Adrenal Axis to Improve Animal Welfare by Means of Genetic Selection: Lessons from the South African Merino

It is a difficult task to improve animal production by means of genetic selection, if the environment does not allow full expression of the animal's genetic potential. This concept may well be the future for animal welfare, because it highlights the need to incorporate traits related to production and robustness, simultaneously, to reach sustainable breeding goals. This review explores the identification of potential genetic markers for robustness within the hypothalamic-pituitary-adrenal axis (HPAA), since this axis plays a vital role in the stress response. If genetic selection for superior HPAA responses to stress is possible, then it ought to be possible to breed robust and easily managed genotypes that might be able to adapt to a wide range of environmental conditions whilst expressing a high production potential. This approach is explored in this review by means of lessons learnt from research on Merino sheep, which were divergently selected for their multiple rearing ability. These two selection lines have shown marked differences in reproduction, production and welfare, which makes this breeding programme ideal to investigate potential genetic markers of robustness. The HPAA function is explored in detail to elucidate where such genetic markers are likely to be found.

Leukotriene modifier vs inhaled corticosteroid in mild-to-moderate asthma: clinical and anti-inflammatory effects

STUDY OBJECTIVE

Evidence for the anti-inflammatory activity of leukotriene receptor antagonists in humans is somewhat limited. There are also no data comparing the anti-inflammatory effects of leukotriene receptor antagonists with those of inhaled corticosteroids. This study was designed to assess the clinical efficacy and anti-inflammatory effects of leukotriene receptor antagonist plus low-dose inhaled corticosteroids compared to those of a high-dose inhaled corticosteroid in patients with mild-to-moderate asthma.

METHODS

Forty-nine patients with newly diagnosed asthma were recruited. They were randomly assigned to groups that received, for a 6-week period, either (1) budesonide, 600 microg bid (1,200 microg/d) or (2) budesonide, 200 microg (400 microg/d), and zafirlukast, 20 mg bid. The variables of asthma control were recorded daily. Sputum induction and methacholine provocation tests were performed.

RESULTS

The results indicated that the administration of a low-dose inhaled corticosteroid plus zafirlukast was as effective as that of a high-dose inhaled corticosteroid regarding clinical improvement and anti-inflammatory effects (ie, eosinophil percentage, and eosinophilic cationic protein [ECP] and cysteinyl leukotriene C4 levels in induced sputum). Nineteen (group 1, 8 patients; group 2, 11 patients) of 49 patients (38.8%) had returned to normal airway responsiveness after treatment. Among these patients, 16 patients (84.2%) had normal ECP levels and 10 patients (52.6%) had normal percentages of eosinophils. ECP level, but not the eosinophil percentage, was significantly associated with symptom scores. The peak expiratory flow rate (PEFR) showed a significant correlation with the provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) instead of with symptom scores.

CONCLUSIONS

The addition of a leukotriene modifier to treatment with low-dose inhaled corticosteroids is equivalent to treatment with high-dose inhaled corticosteroids in patients with newly diagnosed mild-to-moderate asthma. In addition to symptoms and PEFR, the monitoring of ECP and PC20 may be of great value in achieving optimal control of asthma.

Control of chronic nasal symptoms. Directing treatment at the underlying cause

In most patients with rhinitis, careful history taking and physical examination elicit the correct diagnosis. A combination of appropriate environmental and pharmacologic measures is usually effective. Treatment directed at the underlying cause relieves symptoms and improves quality of life. For patients who are unresponsive to treatment, referral to an allergist should be considered. More extensive evaluation and diagnostic testing may reveal previously unrecognized causes of rhinitis.

Glucocorticoid effects on the beta-adrenergic receptor-adenylyl cyclase system of human airway epithelium

BACKGROUND

Activation of the beta(2)-adrenergic receptor (beta(2)AR) system expressed by human airway epithelial cells elicits a variety of cyclic adenosine monophosphate (cAMP)-dependent processes that help determine airway caliber and the intensity of airway inflammation in asthma. Glucocorticoids, mainstays in the treatment of asthma, profoundly affect the expression and function of the beta(2)-adrenergic receptor-adenylyl cyclase (beta(2)AR-AC) system in a variety of cell types. However, the effects of glucocorticoids on the beta(2)AR-AC system expressed by human airway epithelial cells are unstudied.

OBJECTIVE

We examined the effects of dexamethasone (DEX) on beta(2)AR gene expression and the function of the beta(2)AR-AC system in cultured human airway epithelial cells.

METHODS

Studies were performed in normal airway epithelial cells and BEAS-2B cells. Beta(2)AR gene expression was assessed from measurements of beta-adrenergic receptor density, beta(2)AR mRNA, and the activity of a full-length beta(2)AR promoter-luciferase reporter construct. The function of the beta(2)AR-AC system was assessed from cAMP production in response to the beta(2)-agonist isoproterenol and the expression of the stimulatory G protein G(alpha)s.

RESULTS

DEX had no effect on beta-adrenergic receptor density or on the beta(1)/beta(2) ratio over a wide range of concentrations and exposure times. However, DEX significantly but transiently enhanced beta(2)AR mRNA levels (approximately 1.5-fold) and beta(2)AR promoter activity (approximately 1.5-fold), indicating increased beta(2)AR gene transcription. DEX also dose-dependently enhanced cAMP responses to isoproterenol but not to forskolin, a direct activator of adenylyl cyclase. DEX-induced changes in cAMP production were associated with small (approximately 15%) increases in G(alpha)s expression.

CONCLUSIONS

These data indicate that glucocorticoids only transiently enhance beta(2)AR gene transcription and fail to increase steady-state levels of beta(2)AR protein in human airway epithelial cells. Nonetheless, glucocorticoid-induced effects on the beta(2)AR-AC system of human airway epithelial cells contribute to the beneficial effects of corticosteroids in asthma by enhancing the functional response to beta(2)-agonists.

Drug therapy approaches in the treatment of acute severe asthma in hospitalised children

Acute severe paediatric asthma remains a serious and debilitating disease throughout the world. The incidence and mortality from asthma continue to increase. Early, effective and aggressive outpatient therapy is essential in reducing symptoms and preventing life-threatening progression. When complications occur or when the disease progresses to incipient respiratory failure, these children need to be managed in a continuous care facility where aggressive and potentially dangerous interventions can be safely instituted to reverse persistent bronchospasm. The primary drugs for acute severe asthma include oxygen, corticosteroids, salbutamol (albuterol) and anticholinergics. Second-line drugs include heliox, magnesium sulfate, ketamine and inhalational anaesthetics. Future therapies may include furosemide, leukotriene modifiers, antihistamines and phosphodiesterase inhibitors. This review attempts to explore the multitude of medications available with emphasis on pharmacology and pathophysiology.

Analysis of induced sputum to examine the effects of inhaled corticosteroid on airway inflammation in children with asthma

BACKGROUND

Analysis of induced sputum can be performed safely in children with asthma and is useful for both cellular and biochemical markers of inflammation. Glucocorticosteroid inhalation has become the first line therapy for chronic asthma by suppressing airway inflammation, which produces the decrease of bronchial hyperreactivity and reduces the number of eosinophil in bronchial submucosa.

OBJECTIVE

To determine the characteristics of the inflammatory cells and their markers in sputum and to examine the pharmacokinetic effects of glucocorticoid within 3 hours after inhalation therapy on FEV1 and sputum inflammatory indices in children with clinically defined chronic asthma.

METHODS

Thirty subjects with asthma included 14 current symptomatic asthmatics and 14 normal controls inhaled 4.5% hypertonic saline for 10 minutes by nebulizer. The expectorated sputum were collected from all asthmatics before and 3 hours after corticosteroid inhalation for children with asthma and were reduced by dithiotreitol. Total cell counts and differentials were determined. ECP was measured by CAP system. Interleukin-5, GM-CSF and albumin were measured by double sandwich ELISA.

RESULTS

The mean eosinophil percentage and ECP in induced sputum of asthmatics were significantly higher than that of controls. The induced sputum samples obtained after glucocorticoid inhalation showed a significant reduction in mean eosinophil percentage, but FEV1, IL-5, GM-CSF, albumin, and ECP values were not significantly decreased.

CONCLUSION

The present results in induced sputum may be interpreted to reflect direct steroid action on airways and lack of effect on bone marrow effectors at 3 hours after glucocorticoid inhalation.

Inhaled corticosteroid improves bronchial reactivity and decreases symptoms in patients with mitral stenosis

STUDY OBJECTIVE

To determine if treatment with inhaled budesonide forte can diminish increased bronchial hyperreactivity and improve symptoms in patients with mitral valve stenosis.

DESIGN

The study was randomized, double blind, and placebo controlled.

SETTING

Outpatient/university hospital.

PATIENTS

Twelve subjects, 8 female and 4 male, who qualified for mitral valve replacement. All subjects presented with increased bronchial reactivity to histamine at the time of the study.

INTERVENTIONS

Patients received placebo or budesonide forte twice a day (1,200 mg/d) for 6 weeks. During the study, patients were treated with the same doses of diuretics and other medications that could affect bronchial reactivity.

MEASUREMENTS

Spirometry, provocative concentration of histamine causing a 20% fall in the FEV1 (PC20H), symptom scores.

RESULTS

In the treated group, the initial PC20H was 0.82+/-0.72 mg/mL; in the placebo group 1.39+/-1.3 mg/mL. After 6 weeks of treatment, PC20H was significantly higher (3.07+/-2.28 mg/mL; p > 0.01) in the budesonide-treated group and remained unchanged in the placebo group (1.49+/-0.91). Symptom scores were significantly lower after administration of budesonide forte (mean change, 4.0+/-2.6).

CONCLUSIONS

Six weeks of treatment with budesonide forte significantly decreased bronchial reactivity to histamine and improved symptoms in patients with mitral valve stenosis.

Enhanced ocular hypotensive response to epinephrine in rabbits with prior dexamethasone treatment

The purpose of this study was to determine glucocorticoid modulation of ocular pressure to epinephrine applied topically to rabbit eyes that were pretreated with dexamethasone. Rabbit eyes were pretreated with five applications of topical 0.07% dexamethasone (0.1% dexamethasone phosphate) or saline drops, administered at ten minute intervals. The eyes were then treated with epinephrine bitartrate drops at concentrations of free base epinephrine of 1.1%, 0.27%, 0.05%, 0.027%, 0.005% or 0.0005%. An additional group of rabbits received dexamethasone pretreatment only. Intraocular pressure (IOP) was measured for the next four hours. Enhanced lowering of intraocular pressure was observed with dexamethasone pretreatment. Rabbits receiving the smaller dose of epinephrine with dexamethasone had the largest decrease in IOP at 135 minutes after instillation of the epinephrine drops (0.005% epinephrine, mean difference +/- standard error of mean = 5.4 +/- 1.1 mmHg). Similarly, the duration of significant decrease of the IOP was prolonged in the groups receiving the lower concentrations of epinephrine (0.005% epinephrine, 255 minutes after administration of epinephrine). The synergism between glucocorticoids and adrenergic agonists in lowering IOP may be potentially useful in the therapy of ocular hypertension and glaucoma.

Fluticasone propionate aqueous nasal spray treatment for perennial allergic rhinitis in children

BACKGROUND

Topical corticosteroid is now accepted as safe and most effective in controlling all symptoms of both allergic and nonallergic rhinitis. Fluticasone propionate aqueous nasal spray is a new once daily topical corticosteroid preparation.

OBJECTIVE

To evaluate the efficacy and safety of fluticasone propionate in children 5 to 11 years of age with perennial allergic rhinitis.

METHOD

A double-blind, placebo-controlled, parallel group of 127 recruited patients of whom 106 were evaluated. Treatment with once daily fluticasone propionate 100 micrograms or placebo for 4 weeks followed by a 2-week followup period. Fifty-three patients of each group were treated with fluticasone propionate or placebo by randomized assignment.

RESULTS

There was no statistical significance of the sex, mean age, weight, and height of the two groups. Patients treated with fluticasone propionate showed a significant decrease in total symptom scores rated by physicians at 2 weeks and 4 weeks, respectively (P < .01, P < .05). The rhinitis symptom scores in treatment group rated by patients (nasal blockage, sneezing, rhinorrhea) were significantly decreased at 2 weeks (P < .05, P < .01). Nasal symptoms as assessed by doctors (turbinate swelling, color of nasal mucosa, secretion, and postnasal drip) also decreased at 2 and 4 weeks, but were not statistically significant, except for the secretion at 2 weeks and postnasal drip at 4 weeks (P < .05). There was no evidence of effects on adrenal function by morning plasma cortisol concentration between the two groups.

CONCLUSION

Fluticasone propionate was safe and effective in children aged 5 to 11 years with perennial allergic rhinitis.

Regulation of the beta 2-adrenergic receptor and its mRNA in the rat lung by dexamethasone

Glucocorticoids increase beta 2-adrenergic responsiveness and receptor density in the lung, but the underlying mechanisms have not been clearly elucidated. To determine whether changes in beta 2-adrenergic receptor gene expression are involved in vivo, we measured beta 2-adrenergic receptor mRNA levels and beta 2-adrenergic receptor density in lungs from Sprague-Dawley rats treated with a daily injection of dexamethasone (1 mg/kg subcutaneously) for 1, 3, or 7 days. Animals were sacrificed either 2 or 24 h after receiving the last injection. beta 2-Adrenergic receptor mRNA levels were significantly (p < .05) elevated compared to saline-treated controls in the lungs of animals sacrificed 2 h after dexamethasone injection for 1 day (174 +/- 12%), 3 days (236 +/- 18%), and 7 days (220 +/- 11%). Receptor mRNA levels measured 24 h after dexamethasone injection did not differ significantly from the control group. Induction of beta 2-adrenergic receptor mRNA by dexamethasone was transient, since no significant cumulative or sustained increase in receptor mRNA levels was observed during the study period. Treatment with dexamethasone increased beta 2-adrenergic receptor density as expected, but no significant increase in receptor density was detected until 24 h after the third daily injection of dexamethasone, when levels reached 2045 +/- 150 fmol/mg protein compared to 1292 +/- 34 fmol/mg protein in the control group. Receptor density then remained at this elevated level through 7 days of treatment. These results show that dexamethasone up-regulates both the beta 2-adrenergic receptor and its mRNA in vivo in the lung. The induction of beta 2-adrenergic receptor mRNA levels indicates that glucocorticoids may regulate receptor density in the lung through modulation of gene expression. However, the difference between the time course of induction for the beta 2-adrenergic receptor and its mRNA suggests that additional translational or post-translational mechanisms may also be involved.

Preoperative evaluation of children

Preoperative evaluation and preparation are directed toward minimizing the intrinsic risks of anesthesia and surgery by having the child in the healthiest possible condition prior to surgery. The pediatrician can contribute to this goal by understanding the effects of general anesthesia on the physiology of children. This knowledge allows an appreciation of the anesthesiologists' concerns regarding underlying diseases, which may seem "stable" (and, therefore, of little present concern to the pediatrician) but which may have grave consequences during anesthesia. The preoperative evaluation is designed to ensure that the child's preoperative needs may be met by providing the anesthesiologist both qualitative and quantitative information regarding the child's state of health and disease. The relationship between the child, parents, and pediatrician places the pediatrician in an ideal position to prepare families for their children's surgical experience.

Relaxation by dexamethasone of isolated guinea-pig airways precontracted with endothelin-1

Dexamethasone (1-100 microM) produced concentration-dependent relaxations of isolated guinea-pig tracheal and bronchial strips precontracted with endothelin-1 (100 nM), which were not affected by the removal of the epithelium. Dexamethasone neither induced relaxation of tissues precontracted with carbachol (0.1 microM) or KCl (25 mM) nor inhibition of endothelin-1 (1-100 nM)-induced peak contractions after 10-min preincubation of the tissues with dexamethasone. These findings indicate that acute corticosteroid treatment can reverse the bronchoconstrictor action of endothelin-1.

Recovery time course of airway hyperresponsiveness to acetylcholine after ovalbumin challenge in guinea pigs

Sequential changes in airway and adrenergic responsiveness after ovalbumin (OA) challenge were studied in guinea pigs. Airway responsiveness, alpha 1- and beta-adrenoceptor numbers and adenylate cyclase activity was determined after increasing doses of acetylcholine aerosol were administered before, 0, 3, 7, and 14 days after exposure to 2 percent OA or physiologic saline solution for 10 consecutive days. The antiasthmatic agent, azelastine (1 mg/kg/day, intraperitoneal), was administered for 14 days after the tenth exposure to OA in some animals. Airway responsiveness increased significantly after OA exposure, beta-adrenoceptor numbers decreased by 35 percent, and adenylate cyclase activity decreased by 54 percent (p less than 0.01). Values remained significantly different than control animals for 7 days and required 14 days to normalize completely. Azelastine decreased the recovery period to seven days. Azelastine may affect airway responsiveness, at least in part, by increasing beta-adrenergic responsiveness.

Filtration coefficient in isolated preserved and reperfused canine lung

The filtration coefficient (Kf) in Starling's equation for fluid exchange was estimated in isolated reperfused canine lobes to evaluate the effect of ischemia-reperfusion injury on alveolar-capillary permeability quantitatively and to determine the inhibitory effects of a high dose of methylprednisolone (MPS) or dimethylthiourea (DMTU), a potent hydroxyl radical scavenger, on this injury. We reperfused isolated canine left lower lobes (LLLs) with blood at a constant flow after 3 hr of warm (38 degrees C) or cold (4 degrees C) ischemia and measured Kf after 1 hr of reperfusion. The mean value of Kf (+/- 1 SD) in the cold ischemic lobes (COLD, n = 7), 0.13 +/- 0.04 g.min-1.cmH2O-1.100 g-1, was not different from that in the control nonischemic lobes (CONT, n = 6), 0.10 +/- 0.04 g.min-1.cmH2O-1.100 g-1. In contrast, the mean value of the Kf in the warm ischemic lobes (WARM, n = 7), 0.38 +/- 0.17 g.min-1.cmH2O-1.100 g-1, was significantly (P less than 0.001) higher than in CONT.MPS (30 mg/Kg) or DMTU (0.75 g/kg) administered before isolation of LLL and before reperfusion reduced the increase in Kf in warm ischemic lobes to 0.19 +/- 0.09 and 0.19 +/- 0.05 g.min-1.cmH2O-1.100 g-1, respectively (P less than 0.005 WARM vs MPS, and P less than 0.01 WARM vs DMTU). MPS and DMTU also attenuated the impairment of gas exchange. We conclude that (1) reperfusion after 3 hr of warm ischemia increases Kf but after cold ischemia does not, and (2) MPS and DMTU prevent the increase in Kf.(ABSTRACT TRUNCATED AT 250 WORDS)

1,25-Dihydroxyvitamin D3 potentiates the decreased response of lymphocytes from atopic subjects to agents that increase intracellular cyclic adenosine monophosphate

The inhibitory effect of prostaglandin E2, histamine, isobutylmethylxanthine, and 1,25-dihydroxyvitamin D3 (1,25-[OH]2D3) on the mitogenic stimulation of peripheral blood lymphocytes from normal and atopic subjects was studied. We found that lymphocytes from atopic patients were less susceptible to inhibition by the three agents that elevate intracellular cyclic adenosine monophosphate (cAMP) concentrations and by the active metabolite of vitamin D (inhibition of 27%, 14%, 12%, and 36% for the atopic patients as compared with 40%, 20%, 22%, and 46% for the normal donors, by the four agents, respectively; p less than 0.02). The inhibitory effect of the cAMP-elevating agents was potentiated by the addition of 1,25-(OH)2D3 to the lymphocyte cultures. The potentiation was more pronounced on lymphocytes from the atopic donors, increasing their responsiveness to levels comparable to levels of lymphocytes from normal donors. The synthetic corticosteroid, dexamethasone, had a similar potentiating effect on the inhibitory action of prostaglandin E2. In view of the beneficial action of beta-agonists, phosphodiesterase inhibitors, and corticosteroids in the treatment of allergy, the potentiating effect of 1,25-(OH)2D3 on the action of cAMP-elevating agents may be of therapeutic interest.

Comparison of the effects of inhaled corticosteroids on the airway response to histamine, methacholine, hyperventilation, and sulfur dioxide in subjects with asthma

To investigate whether inhaled steroids modulate the airway response to different bronchoconstrictive stimuli, we studied 25 subjects with mild asthma with a double-blind, noncrossover design to compare the effect of a 3-week treatment with salbutamol (0.2 mg, four times a day [q.i.d.]) and placebo (N = 11) to the effect of salbutamol (0.2 mg q.i.d.) and inhaled beclomethasone dipropionate (BDP, 0.5 mg q.i.d.) (N = 14). Airway response to histamine and methacholine was assessed as the provocative concentration (in milligrams per milliliter) necessary to increase the specific airway resistance (SRaw) (in centimeters of H2O times second) by 100% (PC100 SRaw). Airway response to hyperventilation of air and to hyperventilation of 0.75 ppm of sulfur dioxide (SO2) was determined as the provocative ventilation (in liters per minute) necessary to increase SRaw by 75% (PV75 SRaw). Challenges were performed on separate days before and after treatment, and salbutamol inhalation was withheld at least 6 hours before each challenge. Salbutamol and placebo did not change perchallenge baseline SRaw nor did they have any significant effect on the airway response to the stimuli. Salbutamol and BDP decreased the mean prechallenge baseline SRaw (SEM) from 7.7 (0.37) to 5.9 (0.28) (p less than 0.01) and significantly (p less than 0.01) increased geometric mean (SEM) PC100 SRaw for histamine from 0.5 (1.42) to 0.9 (1.53) mg/ml; for methacholine, from 0.2 (1.47) to 0.5 (1.51) mg/ml; and mean (SEM) PV75 SRaw for hyperventilation of air from 51.8 (2.32) to 58.4 (1.86) L/min. In contrast, the change of PV75 SRaw during hyperventilation of SO2 from 26.2 (2.29) to 31.4 (3.30) L/min was not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Rationale and use of corticosteroids in chronic obstructive pulmonary disease

Several studies of corticosteroid efficacy in patients with COPD performed in the last decade have had stronger study designs and larger patient populations than most of the previously reported investigations. These studies have provided evidence of the objective benefit of corticosteroid therapy on pulmonary function in clinically stable COPD patients. These positive results are due to a relatively marked beneficial effect of corticosteroids in a minority of the subjects studied rather than a modest effect in the majority of subjects. A controlled randomized trial of intravenous corticosteroid administration in patients with COPD and acute respiratory failure admitted to the hospital showed improvement in pulmonary function from 12 hours following initial administration through the remainder of the 3 days of the study in the treatment group as compared to the control group. A greater percentage of patients showed a beneficial response to corticosteroids in this study of patients with acute exacerbations as compared to most of the studies of clinically stable COPD patients with beneficial effects. This suggests the possibility that some patients may show a beneficial response to corticosteroids during an acute exacerbation although they have not shown a response when clinically stable. The response to inhaled corticosteroids in patients with COPD has not been studied as extensively as the response to oral corticosteroids. However, some studies have shown a beneficial response to inhaled corticosteroids, primarily but not exclusively, in individuals who have also shown a positive response to oral agents. Generally, the response in terms of improved pulmonary function has been less striking with the inhaled agent as compared to the oral drug, although higher relative doses of the oral drugs usually were studied. Several limitations of the currently available studies are evident. Most of the studies deal with the effects in clinically stable outpatients with COPD and no studies have dealt with maintenance therapy in patients who have responded to a 1 to 2 week course of 30 mg of prednisone or greater. Data on the efficacy of inhaled corticosteroids in COPD patients are limited. No studies have investigated the role of corticosteroids in acute exacerbations in outpatients with COPD. Recommendations are given regarding use of corticosteroids in patients with COPD. A trial of corticosteroids is recommended at some point during a patient's course, while clinically stable. If a beneficial response is obtained in terms of improvement in airflow obstruction, then clinical judgment must be used regarding whether maintenance therapy is continued and, if so, at what dose and by what route.(ABSTRACT TRUNCATED AT 400 WORDS)

Alternative approaches to asthma

On the basis of studies of the pathophysiology of asthma, we now know that agents to control chronic asthma must do more than reverse bronchoconstriction caused by a hyperreactive airway. They must also control the inflammatory response engendered by the triggers of asthma. Three types of antiinflammatory agents are now used for this purpose: corticosteroids, cromolyn sodium, and a new anticholinergic drug, ipratropium bromide. These drugs are discussed in terms of their mechanisms of action, clinical uses, and side effects reported in studies of children with asthma.

The effect of leukotriene antagonists, lipoxygenase inhibitors and selected standards on leukotriene-mediated allergic bronchospasm in guinea pigs

Leukotrienes (LT) C4, D4, and E4 are major contributors to the pathobiology of human bronchial asthma. Therefore, it is likely that compounds that antagonize the action or inhibit the formation of LTs will be useful therapeutic agents. We have studied the effects of LT antagonists, 5-lipoxygenase inhibitors and selected standards in a model of LT-mediated allergic bronchospasm in guinea pigs. Sensitized animals were pretreated with mepyramine, indomethacin and propranolol to eliminate the influence of histamine, prostaglandins, thromboxanes and circulating catecholamines. In these animals, inhalation of antigen resulted in a bronchospasm consistent with a LT-mediated response that was slow in onset, of long duration and was inhibited by the selective LTD4, antagonists FPL-55712, LY-171,883 and ICI-198,615. ICI-198,615 was approximately 50-times more potent than FPL-55712 by the intravenous and intratracheal routes. However, of thirteen compounds known to inhibit 5-lipoxygenase and LT biosynthesis in vitro only phenidone, piriprost and AA-861 were active in this in vivo model. The allergic bronchospasm was inhibited by bronchodilators (e.g. PGE2, aminophylline and forskolin) and by some mast cell stabilizers, but was otherwise insensitive to other pharmacological classes of compounds including calcium channel blockers and antagonists of serotonin, acetylcholine and platelet-activating factor. This model seems useful and reasonably selective for the evaluation of new antianaphylactic compounds that are LT antagonists. The inactivity of many 5-lipoxygenase inhibitors in this model suggests they do not inhibit LT formation in vivo.

Dexamethasone attenuates microvascular ischemia-reperfusion injury in the rat cremaster muscle

We examined the effect of dexamethasone (DXM) pretreatment on microvascular transport of macromolecules in ischemia-reperfusion injury. The rat cremaster muscle was splayed, placed in a Lucite intravital chamber, and suffused with bicarbonate buffer. The clearance of fluorescein isothiocyanate-dextran 150 (FITC-Dx 150) was measured as an index of microvascular transport. After determination of baseline data, the muscle was made ischemic for 2 hr by clamping its vascular pedicle, and subsequently reperfused for 2 hr. Ischemia-reperfusion produced a marked increase in clearance of FITC-Dx 150. After an initial peak of 13 times baseline value clearance fell to approximately 4 times baseline level 30 min into the reperfusion period. Clearance increased slowly throughout the remainder of the experiment, reaching 6 times baseline after 2 hr of reperfusion. The treated animals received DXM 3 hr prior to and immediately preceding the pedicle clamping. DXM reduced macromolecular clearance significantly after the first 30 min of reperfusion, and prevented the increase in clearance over time. After an initial peak, clearance values fell to near twice baseline in DXM-treated animals, and remained at this level for the 2 hr of reperfusion. Our data demonstrate that DXM attenuates the alternations in microvascular macromolecular transport produced by ischemia-reperfusion injury.

Effect of azelastine, an antiasthmatic drug, on bronchial responsiveness in patients with bronchial asthma

This study was designed to clarify whether azelastine, an antiasthmatic drug, could favorably alter bronchial responsiveness in patients with bronchial asthma. To estimate bronchial responsiveness, methacholine challenge was performed in 21 patients with bronchial asthma. After the first examination, all patients were treated for eight weeks with azelastine, 2 mg twice daily. After four and eight weeks' treatment, methacholine challenge was repeated. After eight weeks' treatment, Dmin, an index of bronchial sensitivity, was increased significantly, and after four weeks an insignificant increase was observed. The RrsC, SGrs/GrsC, indices of respiratory resistance and bronchial reactivity, respectively, did not change significantly during eight weeks' treatment. Recently various chemical transmitters, especially leukotrienes, were shown to be closely related to the genesis of bronchial asthma. Accordingly, the effect of azelastine observed here might be ascribed to its antagonizing action on leukotriene. Since bronchial hyperresponsiveness is a critical etiologic factor in bronchial asthma, long-term administration of azelastine might help to modify the disease's basic pathophysiologic conditions.

Management of bee-sting anaphylaxis

A retrospective case analysis of 101 adverse reactions to bee-stings and a prospective questionnaire analysis of the proposed management by local medical practitioners and resident hospital staff members of three hypothetical bee-sting reactions has revealed that understanding of the use of adrenaline in patients with reactions to bee envenomation is confused with regard to the indications for its use, dosage and route; that corticosteroid agents are used or are recommended too frequently, sometimes as the sole therapeutic agent; and that there is a lack of awareness of the need for volume replacement in hypotensive shocked patients. These conclusions highlight the urgent need for a greater understanding of the optimal forms of management for patients with acute anaphylactic reactions to bee envenomation.

The wheezing infant

In summary, wheezing is a common manifestation of viral respiratory tract disease in infancy. The precise pathogenetic mechanisms of virus-induced wheezing and its sequelae are not clear, although recent reports about participation of the cellular and humoral immune systems are promising. Although therapies like those used to treat asthma are employed in the treatment of virus-induced wheezing in infancy, their efficacy remains controversial in bronchiolitis. Recently developed agents with antiviral properties are promising and the choice of any of these agents in a therapeutic regimen should be individualized. Antiviral agents during acute infections may modify the long-term sequelae. Clearly, much work needs to be done to elucidate pathogenetic mechanisms, and to develop new, safe, and effective anti-inflammatory agents for the therapy of these disorders.

Evaluation of the combination inhaler of salbutamol and beclomethasone dipropionate in the management of asthma

An open parallel study lasting 24 weeks was performed in 39 asthmatics to evaluate patient compliance and the clinical effects of regular inhalations of beclomethasone dipropionate and salbutamol used simultaneously from a combination inhaler with regular inhalations of salbutamol and beclomethasone dipropionate used sequentially from separate inhalers. Total daily doses in the two groups were 800 micrograms salbutamol and 400 micrograms beclomethasone dipropionate. There were no differences between the two treatment groups with respect to clinic pulmonary function tests (FEV1, FVC), daily PEF measurements, symptom scores, use of symptomatic bronchodilator therapy, requirements for extra medication and patients' and physician's assessment of treatment. At 12 weeks, the physician assessed significantly more patients to have better symptom control on the combination inhaler than on separate inhalers. Patient compliance was high in both treatment groups which may have been due to the close supervision of the clinical study.

Binding of dexamethasone and its effect on histamine release from rat mast cells

Purified rat peritoneal mast cells were incubated for 20 h with or without dexamethasone (4 x 10(-6) M) and then passively sensitized with serum from Trichinella spiralis-infected rats. The release of histamine using various secretagogues (concanavalin A, crude antigen of T. spiralis and polymyxin B) was determined. Dexamethasone treatment markedly inhibited IgE-dependent release of histamine (from 33.9 +/- 5.0% to 12.4 +/- 5.1% and from 39.8 +/- 7.9% to 14.2 +/- 6.5% of total cellular histamine content, respectively) whereas histamine release stimulated by the nonimmunological stimulus, polymyxin B was unaffected by this steroid. This suggests that the effects of dexamethasone cannot be exclusively explained by inhibition of phospholipases. Specific binding of 3H-dexamethasone to purified mast cells displayed sigmoidal dependence on concentration which may be the result of either negative cooperativity or the presence of a different class of binding sites. Two saturation plateaux at 20-30 x 10(-9) M and 70-90 x 10(-9) M were observed. The equilibrium dissociation constant for the higher affinity binding sites was Kd1 = 1.9 x 10(-8) M and represented 25,290 sites/cell, whereas the apparent Kd2 for lower affinity sites amounted to 5.5 x 10(-8) M and represented about 120,000 sites/cell.

Pretreatment with corticosteroids to alleviate reactions to intravenous contrast material

The x-ray contrast mediums used over the past three decades have been salts of iodinated acids administered in highly hypertonic concentrations. We conducted a multiinstitutional randomized study of the protective effects of pretreatment with corticosteroids against reactions to intravenous contrast material. We gave 6763 patients two doses of oral corticosteroids (methylprednisolone, 32 mg) approximately 12 hours and 2 hours before challenge with contrast material, one dose of oral prednisolone approximately 2 hours before challenge, or placebo in the same dosages. The two-dose corticosteroid regimen, but not the one-dose regimen, significantly reduced the incidence of reactions of all types (P less than 0.05) except a category of reactions dominated by hives, for which the reduction approached significance (P = 0.055). In recent years, several relatively expensive monomeric nonionic iodinated compounds having approximately half the osmolality of the corresponding ionic compounds and a lower reaction rate have become available. With our two-dose corticosteroid regimen, the incidence of reactions necessitating therapy in patients receiving the ionic medium approximated that reported in an unblinded nonrandomized study of patients receiving a newer intravenous nonionic medium without corticosteroid pretreatment. We conclude that the much less expensive ionic medium, if administered with corticosteroid pretreatment, may serve as a reasonable alternative to intravenous nonionic medium, without loss of safety.

Aerosol corticosteroids for the treatment of asthma

In an effort to maximize the efficacy of corticosteroid treatment in asthma and minimize the adverse reactions, steroid therapy has evolved to the inhalation route of administration with aerosol compounds having potent topical antiinflammatory activity and minimal systemic effects. Corticosteroids exhibiting these properties that are available in the U.S. include beclomethasone dipropionate, triamcinolone acetonide, and flunisolide. The success or failure of patient response to orally inhaled corticosteroids is often a function of adequate drug delivery rather than the efficacy of the drug itself. Patients who cannot use the inhaler accurately may benefit from the use of a spacer or reservoir device. The three aerosolized corticosteroids have specific pharmacologic differences; however, none of these differences has translated into a clinically significant advantage or disadvantage of one product over the others. These agents should be considered for adjunctive therapy in patients whose asthma is not adequately controlled by beta-agonist bronchodilators, theophylline, or cromolyn sodium.

The inflammatory theory of asthma

In summary, these observations suggest a model for asthma which is summarized in Table III. Initially, mast cells and possibly other bronchial cells, e.g., alveolar macrophages, are activated either in an IgE-dependent or, in intrinsic asthma, in an IgE-independent fashion. These cells release two sets of mediators which may be either preformed or newly synthesized. One set of mediators is responsible for the immediate bronchospastic response. This bronchospasm is transient, readily reversible, and not associated with either airway inflammation or bronchial hyperreactivity. The second set of mediators, however, promote chemotaxis and activation of neutrophils and eosinophils. The subsequent bronchial inflammation causes damage and desquamation of the respiratory epithelium. The increased exposure of irritant receptors results in hyperreactive airways. In addition, these inflammatory cells induce mast cell degranulation and recurrent bronchospasm. Thus, after the initial exposure to allergen, a vicious cycle of inflammation, hyperreactivity and recurrent mast cell degranulation develops, ultimately leading to the pathological picture of chronic asthma.

Effects of nebulized fenoterol, associated with ipratropium or steroids, on the heart rate of infants under one year of age with acute wheezing

The main objective of this study was to evaluate the effect of fenoterol alone or associated with ipratropium bromide or steroid on the heart rate in young children. Ninety-four infants less than 1 year of age were randomly allocated to receive nebulized fenoterol alone, fenoterol plus ipratropium bromide, fenoterol plus corticosteroids, or normal saline solution. An increase in heart rate was observed in all four groups. The increases were statistically significant (P less than 0.001) in all three treatment groups, and no difference between them was observed (F = 0.65, NS). However, the heart rate remained within clinically acceptance limits. We conclude that nebulized fenoterol alone or combined with ipratropium or steroids can be safely used in the treatment of wheezy infants.

Supraventricular tachycardia in patients with cystic fibrosis

Reports on arrhythmias in cystic fibrosis (CF) patients are limited. Four CF patients treated at our center had recurrent supraventricular tachycardia (SVT). Three had cor pulmonale, as evidenced by echocardiogram, and all had baseline tachycardia. Twenty-four hour Holter monitoring in three patients showed ectopic atrial pacing and premature atrial and ventricular contractions in one patient, rare PVCs in another, and SVT in all three. All patients had significant bronchospasm requiring the use of theophylline, prednisone, and frequent daily doses of beta-2 adrenergic agonists; two also used nebulized atropine. Average theophylline level for the group was 13.4 micrograms/ml during SVT. There was no correlation between pulmonary obstruction and the frequency of SVT. Factors such as cor pulmonale, ectopy, hypoxia, infection, intensive combination bronchodilator therapy, and corticosteroids probably interacted to precipitate SVT. Altered autonomic responses and a myocardial infiltrative process noted in some patients with CF may also play a role in causing arrhythmias.