Suppression of airway hyperresponsiveness induced by ovalbumin sensitisation and RSV infection with Y-27632, a Rho kinase inhibitor.

BACKGROUND: Smooth muscle contraction is one of the hallmarks of asthma. A recently developed pyridine derivative, Y-27632, a selective Rho kinase inhibitor, has been reported to inhibit the smooth muscle contraction of human and animal trachea in ex vivo systems but its effect in animal models of airway hyperresponsiveness (AHR) has not been examined. The purpose of this study was to evaluate the effect of Y-27632 in a murine model of allergic and virally induced AHR. METHODS: Baseline lung resistance and methacholine induced AHR were measured in mice sensitised to ovalbumin (OVA) and also in mice infected with respiratory syncytial virus (RSV) following ovalbumin sensitisation (OVA/RSV). RESULTS: Time course and dose ranging experiments indicated that 30 mg/kg Y-27632 given by gavage 2 hours before methacholine challenge significantly reduced baseline lung resistance and prevented AHR in OVA sensitised mice. Y-27632 also suppressed AHR induced by the bronchospastic agent serotonin in OVA sensitised mice and prevented methacholine induced AHR in OVA/RSV mice. CONCLUSIONS: These results suggest that the signalling pathway mediated through Rho kinase may have an important role in bronchial smooth muscle tone in allergen induced and virus induced AHR and should be considered as a novel target for asthma treatment.

Assessment of oxidant stress in allergic asthma by measurement of the major urinary metabolite of F2-isoprostane, 15-F2t-IsoP (8-iso-PGF2alpha).

Asthma is a chronic inflammatory disease of the airways which may involve an oxidant injury to the lung. Assessment of oxidant stress is difficult in vivo, but measurement of F2-isoprostanes (F2-IsoPs), free radical-catalysed products of arachidonic acid, appears to offer a reliable approach for quantitative measurement of oxidative stress status in vivo. We have recently developed a mass spectrometric assay for 2,3-dinor-5,6-dihydro-15-F2t-IsoP (15-F2t-IsoP-M), the major urinary metabolite of the F2-IsoP, 15-F2t-IsoP (8-iso-PGF2a). Measurement of the urinary excretion of this metabolite offers a reliable index of oxidative stress status in vivo that has advantages over measuring unmetabolized F2-IsoPs in urine and plasma. To assess the occurrence of oxidative stress in patients with atopic asthma following allergen exposure in vivo by measuring the urinary excretion of 15-F2t-IsoP-M. Analysis of 15-F2t-IsoP-M by GC-NICI-MS in nine mild atopic asthmatics following inhaled allergen provocation and four asthmatic subjects after inhaled challenge with methacholine. Urinary excretion of 15-F2t-IsoP-M increased at 2 h after allergen challenge and remained significantly elevated in all urine collections during the subsequent 8-h period of the study compared to the baseline value (ANOVA, and Student-Newman-Keuls multiple comparisons test). No increase in the urinary excretion of 15-F2t-IsoP-M occurred after inhalation of methacholine. Allergen challenge causes an oxidant injury in human atopic asthmatics. 15-F2t-IsoP-M is a valuable marker of oxidant stress in vivo.

Dietary antioxidants and adult asthma.

The triggers and causes of asthma have long been topics of investigation by epidemiologists. The current concept of asthma and atopy is that the onset of the disease and its clinical course are determined by gene environment interactions; that is, those individuals who develop asthma are both genetically susceptible and receive appropriate environmental stimuli. One potential environmental factor that may relate to disease etiology is diet. This article will review the published evidence for the effects of dietary antioxidants on asthma incidence and disease control.

Prostaglandin E(2) decreases allergen-stimulated release of prostaglandin D(2) in airways of subjects with asthma.

Prostaglandin E(2) (PGE(2)) inhibits the early and late bronchoconstrictor response to inhaled allergen. The mechanisms of action, however, are not understood. We investigated the effect of inhaled PGE(2) on the release of prostaglandin D(2) (PGD(2)), preformed mast cell mediators, and other products of arachidonic acid metabolism. We compared inhaled PGE(2) (100 microgram) to placebo in a randomized double-blind crossover study. Ten atopic asthmatics underwent bronchoscopy immediately after inhalation of PGE(2) or placebo. Bronchoalveolar lavage (BAL) was performed at baseline, and in a separate segment 4 min after allergen instillation. Nebulized PGE(2) was well tolerated. PGE(2) concentrations in baseline lavage fluid were significantly greater after PGE(2) inhalation than after placebo. PGD(2) concentrations after allergen challenge were significantly reduced in those subjects receiving nebulized PGE(2) compared with control subjects. We conclude that PGE(2) can be safely delivered by inhalation. Nebulized PGE(2) administered before to segmental allergen challenge reduced PGD(2) in BAL fluid (BALF). PGE(2) also decreased the production of other mediators of the arachidonic acid pathway, although not significantly. The reduction of PGD(2) may be part of the mechanism by which PGE(2) blocks the early asthmatic response.

Underutilization of controller and rescue medications among older adults with asthma requiring hospital care.

BACKGROUND: Asthma causes serious morbidity in older people, but pharmacologic therapy in older people with asthma has never been studied, at least in part because of the difficulty of defining asthma in this population. OBJECTIVE: To determine if older persons enrolled in Medicaid and hospitalized with an exacerbation of asthma receive appropriate outpatient asthma care. DESIGN: Descriptive pharmacoepidemiology of a group of older adults with asthma. SETTING: The Tennessee Medicaid Program. PARTICIPANTS: Persons aged 65 and older, enrolled in the Tennessee Medicaid program, identified through Medicaid's computerized database as having a hospital care visit for asthma in 1992 and who had their diagnosis confirmed by chart review. MEASUREMENT: Medication utilization. RESULTS: The source population included 93,686 persons aged 65 or older enrolled in the Tennessee Medicaid program. The group meeting study criteria included 512 patients with chronic asthma who had a hospital care visit for an asthma exacerbation. Eighty-one percent of these 512 persons with an asthma hospitalization confirmed by chart review were classified as having moderate to severe or potentially fatal asthma. These patients had had a median of 15 outpatient visits in the previous year, and more than half of them had an outpatient visit in the 14 days before their hospitalization. However, among those with moderate to severe or near fatal asthma only 25% filled prescriptions for inhaled corticosteroids, whereas 52% were taking theophylline, the most commonly prescribed asthma medication in this group. There was also high use of antibiotics (29%) and low use of rescue corticosteroids (5%) before the hospital care visit, despite frequent medical encounters. CONCLUSIONS: Despite widespread promulgation of the National Asthma Education Prevention Program guidelines, our study suggests that providers caring for indigent older subjects with moderate to severe or potentially fatal asthma were not following these guidelines. There was significant underutilization of inhaled anti-inflammatory agents, beta-agonists, and rescue corticosteroids in this population despite frequent outpatient medical care visits.

Epidemiology of asthma: the year in review.

Asthma is a worldwide problem, with more than 17 million persons in the United States estimated to have asthma, and there is evidence that the prevalence is increasing. This article reviews the latest epidemiologic evidence for an increase in asthma prevalence and morbidity, and the evidence that environment plays a significant role in this disease. This review focuses on five specific areas: prevalence, incidence, natural history, environmental factors, and morbidity and mortality.

Respiratory viruses and asthma.

Viral infections have become increasingly recognized as a significant cause of asthma exacerbations, mainly because of improved viral detection techniques. Unfortunately, the ability to specifically treat viral infections and to limit the asthma morbidity associated with these agents has not kept pace with diagnostic technology. This article focuses on current concepts of the epidemiology of viruses in asthma exacerbations, investigations studying the physiologic and immunologic consequences of viral infection, and potential therapies to minimize virally-induced airway hyperresponsiveness. To impact this significant health problem, researchers must definitively ascertain the mechanisms by which viruses induce airway reactivity and must develop rational, safe approaches to prevent the consequences of viral infection in the patient with asthma.

Use of pulse oximetry to recognize severity of airflow obstruction in obstructive airway disease: correlation with pulsus paradoxus.

STUDY OBJECTIVES: The purpose of this cross-sectional study was to confirm the observation that pulse oximetry tracing correlates with pulsus paradoxus, and is therefore a measure of the severity of air trapping in obstructive airway disease. DESIGN: Cross-sectional survey. SETTING: The ICU in a tertiary care academic hospital. PATIENTS: Twenty-six patients consecutively admitted to the ICU with obstructive airway disease, either asthma or COPD. MEASUREMENTS AND RESULTS: Forty-six percent of the study patients required mechanical ventilation, and 69% had an elevated pulsus paradoxus. We defined the altered pulse oximetry baseline tracing as the respiratory waveform variation (RWV). The RWV was measured in numerical form as the change in millimeters from the baseline. Pulsus paradoxus was significantly correlated with the RWV of the pulse oximetry tracing (p < 0.0001). An analysis of the respiratory variations in the pulse oximetry waveforms in obstructive lung disease patients reflects the presence and degree of auto-positive end-expiratory pressure (auto-PEEP; p < 0.0001). CONCLUSIONS: We describe the characteristic alterations in the pulse oximetry tracings that occur in the presence of pulsus paradoxus and auto-PEEP. Since pulse oximetry is available universally in ICUs and emergency departments, it may be a useful noninvasive means of continually assessing pulsus paradoxus and air trapping severity in obstructive airway disease patients.

Viral infections in asthma.

This article summarizes recent findings regarding the impact of viruses on reactive airway disease. Technical breakthroughs are improving our ability to diagnosis viral infections. However, the real breakthrough will come when pharmacologic interventions can specifically prevent the symptoms of virally induced asthma.

In vivo diagnostic procedures: skin testing, nasal provocation, and bronchial provocation.

In vivo challenge procedures can be very useful in the analysis of allergic symptoms. Skin testing has a high degree of sensitivity and specificity for determining antigens that cause allergic disease. However, positive skin tests do not necessarily indicate that a specific allergen causes symptoms specific for a certain organ. Nasal and whole lung provocation testing can help define relevant allergens that cause rhinitis or asthma symptoms. These tests are safe when performed properly under close medical supervision and have predictive values that make them useful diagnostic tools.

Oral antibiotic treatment of right-sided staphylococcal endocarditis in injection drug users: prospective randomized comparison with parenteral therapy.

PURPOSE: To compare the efficacy and safety of inpatient oral antibiotic treatment (oral) versus standard parenteral antibiotic treatment (intravenous) for right-sided staphylococcal endocarditis in injection drug users. PATIENTS AND METHODS: In a prospective, randomized, non-blinded trial, febrile injection drug users were assigned to begin oral or intravenous (IV) treatment on admission, before blood culture results were available. Oral therapy consisted of ciprofloxacin and rifampin. Parenteral therapy was oxacillin or vancomycin, plus gentamicin for the first 5 days. Antibiotic dosing was adjusted for renal dysfunction. Administration of other antibacterial drugs was not permitted during the treatment or follow-up periods. Bacteremic subjects having right-sided staphylococcal endocarditis received 28 days of inpatient therapy with the assigned antibiotics. Test-of-cure blood cultures were obtained during inpatient observation 6 and 7 days after the completion of antibiotic therapy, and again at outpatient follow-up 1 month later. Criteria for treatment failure and for drug toxicity were prospectively defined. RESULTS: Of 573 injection drug users who were hospitalized because of a febrile illness and suspected right-sided staphylococcal endocarditis, 93 subjects (16.2%) had two or more sets of blood cultures positive for staphylococci; 85 of these bacteremic subjects (14.8%) satisfied diagnostic criteria for at least possible right-sided staphylococcal endocarditis (no other source of bacteremia was apparent) and entered the trial. Forty-four (oral, 19; IV, 25) of these 85 subjects completed inpatient treatment and evaluation including test-of-cure blood cultures. There were four treatment failures (oral, 1 [5.2%]; IV, 3 [12.0%]; not significant, Fisher's exact test). Drug toxicity was significantly more common in the parenterally treated group (oral, 3%; IV, 62%; P < 0.0001), consisting largely of oxacillin-associated increases in liver enzymes. CONCLUSIONS: For selected patients with right-sided staphylococcal endocarditis, oral ciprofloxacin plus rifampin is effective and is associated with less drug toxicity than is intravenous therapy.

Inadequate outpatient medical therapy for patients with asthma admitted to two urban hospitals.

PURPOSE: To determine the patterns of chronic outpatient management in urban patients with moderate and severe asthma, and to assess medical practice adherence to the Guidelines for the Diagnosis and Management of Asthma from the National Asthma Education Program (NAEP). PATIENTS AND METHODS: This is a cross-sectional survey of adult patients with asthma admitted to the general medical services at the Johns Hopkins Medical Institutes (Johns Hopkins Hospital and Johns Hopkins Bayview Medical Center) Baltimore, Maryland. Subjects were 101 adults admitted with an asthma exacerbation from February 1992 through January 1993. Using a validated questionnaire, these subjects were surveyed within 48 hours of admission concerning their chronic outpatient medical management and the measures patients or their physicians took to alleviate symptoms during the asthma exacerbation leading to hospitalization. RESULTS: The average asthma admission rate in the past year for this group of patients was 2.5, indicative of moderate to severe disease. Less than half of these patients had been prescribed inhaled anti-inflammatory therapy. Of the patients who had previously been shown the metered dose inhaler technique by a health care professional, 11% could perform all components of this technique correctly. Only 28% of patients had been given an action plan by their physician in the event of an acute exacerbation. Sixty percent of patients who contacted their physician during the exacerbation that preceded admission had no changes made in their treatment regimen. In those whose exacerbation lasted at least 24 hours, the average beta-agonist metered dose inhaler use during the 24 hour prior to admission was 44.8 +/- 7.8 puffs (mean +/- standard error of the mean). Older age, (current smoking, and race (black) were the most significant correlates of inhaled beta-agonist use during this period. CONCLUSIONS: This is the first documentation of multiple problems in conforming with the standards of care delineated by the NAEP as they relate to the outpatient management of inner-city patients with moderate to severe asthma in the United States. In this population of patients with asthma, management was characterized by underutilization of anti-inflammatory therapy, inability to use inhalation devices properly, inadequate communication between patient and physician of an action plan to be utilized in the event of an acute exacerbation and inadequate physician intervention during the acute stages of the exacerbation. There was also overutilization of inhaled beta-agonists during exacerbations. It is imperative that these aspects of management, for which the NAEP has set standards of care, are addressed as part of the effort to reduce asthma morbidity in the urban United States.