Bronchial asthma

Asthma Patient Education

Patient education is a very important aspect of the treatment of asthma. Success of therapy is highly dependent upon patients' knowledge of asthma and the correct use of their medications. Over the last decade the morbidity and mortality rates due to asthma have increased. Education of patients is necessary to reduce these rates. Pharmacists can play a major role in the education of patients. Pharmacists are readily available and see most patients frequently for refills. Regular use of anti-inflammatory medications, use of β2-agonists for rescue therapy, and prevention of exercise induced asthma, and correct inhaler technique should be stressed. Spacer devices and peak flow meters should be routinely recommended by pharmacists. Educational aids such as handouts, pamphlets, and video tapes are available from many different organizations that can help make education more time efficient. Asthma education is a rewarding service to offer asthma patients and helps to develop loyalty as well as overall better health care for patients.

The pivotal role of airway smooth muscle in asthma pathophysiology

Asthma is characterized by the association of airway hyperresponsiveness (AHR), inflammation, and remodelling. The aim of the present article is to review the pivotal role of airway smooth muscle (ASM) in the pathophysiology of asthma. ASM is the main effector of AHR. The mechanisms of AHR in asthma may involve a larger release of contractile mediators and/or a lower release of relaxant mediators, an improved ASM cell excitation/contraction coupling, and/or an alteration in the contraction/load coupling. Beyond its contractile function, ASM is also involved in bronchial inflammation and remodelling. Whereas ASM is a target of the inflammatory process, it can also display proinflammatory and immunomodulatory functions, through its synthetic properties and the expression of a wide range of cell surface molecules. ASM remodelling represents a key feature of asthmatic bronchial remodelling. ASM also plays a role in promoting complementary airway structural alterations, in particular by its synthetic function.

Asthma prevalence associated with geographical latitude and regional insolation in the United States of America and Australia

BACKGROUND

It has been proposed that vitamin D deficiency may be responsible for an increase in the prevalence of allergic diseases and asthma worldwide. Human ability to generate physiologically required quantities of vitamin D through sun exposure is decreasing with increasing geographical latitude.

OBJECTIVES

Considering that vitamin D deficiency is usually due to lack of outdoor sun exposure, this study is designed to test the hypothesis that a higher prevalence of asthma should be expected at high relative to low geographical latitudes.

METHODS

Linear regression analyses are performed on asthma prevalence in the U.S. adult population vs. geographical latitude, insolation, air temperature, and air pollution (PM(2.5)) for 97 major metropolitan/micropolitan statistical areas of the continental United States of America and on general population asthma prevalence vs. geographical latitude in eight metropolitan areas of Australia.

RESULTS

A 10° change in geographical latitude from southern to northern regions of the Eastern Seaboard is associated with a 2% increase in adult asthma prevalence (p<0.001). Total insolation in winter months is almost as strong as latitude in its ability to explain the observed spatial variation in the prevalence of asthma (r(2) = 0.43; p<0.001). Similar results are obtained using the Australian data (r(2) = 0.73; p<0.01), suggesting a consistent association between the latitude/insolation and asthma prevalence worldwide.

CONCLUSIONS

The results of this study suggest that, as a known modulator of the immune response closely linked with the geographical latitude and erythemal UV irradiation, vitamin D may play an important role in the development/exacerbation of asthma.

Event-related potentials to inspiratory flow-resistive loads in young adults: stimulus magnitude effects

Event-related potentials were recorded to brief presentations of four levels of inspiratory flow-resistive loads in young adults. We labeled the loads according to the level of resistance they provided subjectively: sub-threshold (0.34 cmH2O/l per s), near-threshold (4.01 cmH2O/l per s), intermediate (10.4cmH2O/l per s), and near-occlusion (57.5 cmH2O/l per s). No discernible ERPs were elicited by the undetected, sub-threshold stimulus but late components of the ERP (P2, N2, and P3) were observed to each of the three larger stimuli. They were related, in part, to behavioral judgments obtained during the stimulus periods. Both the latency and amplitude of the ERP components varied systematically as a function of stimulus magnitude, in a manner comparable to that observed in ERP paradigms using auditory and visual stimuli. Thus, the data show that event-related potentials to breathing are sensitive to physiologic effects of resistive loads present at the onset of inspiration. Respiratory ERPs may be used to infer sensory and perceptual responses to increases in airflow resistance and, accordingly, may relate to the perception of airflow obstruction in patient populations.

Histamine stimulates a biphasic calcium response in the human tracheal epithelial cell line CF/T43

We have studied the cytosolic free Ca2+ concentration ([Ca2+]i) response to histamine and other inflammatory mediators in a cystic fibrosis tracheal epithelial cell line (CF/T43) using digital fluorescence imaging. Brief pulses of histamine increased [Ca2+]i in a concentration-dependent manner with threshold, half-maximal, and maximal responses at approximately 5 microM, 120 microM, and 10 mM, respectively. The calcium response to sustained histamine exposure was markedly biphasic, consisting of an early peak (to approximately 2.4 microM [Ca2+]i) followed by a smaller second peak that lasted 45-60 s. Neither peak was directly dependent on Ca2+ influx. In contrast, stimulation with bradykinin gave a single peak followed by a smooth decay back to baseline levels. Sustained perfusion with histamine did not affect the bradykinin response, which is known to be mediated by inositol 1,4,5-trisphosphate (IP3). The H1-type histamine receptor blockers mepyramine, diphenhydramine, and (+)-chlorpheniramine were potent antagonists of the histamine response. Diphenhydramine was also a weak agonist at high concentrations (> or = 1 mM) and gave a biphasic response similar to that with histamine. The H2-type receptor blocker cimetidine and the H3-type receptor blocker thioperamide had no effect. Indomethacin failed to inhibit the second phase of the histamine-stimulated [Ca2+]i response, suggesting that the second [Ca2+]i peak is not due to secondary production of prostaglandins. Neomycin, which inhibits IP3 production, completely abolished the [Ca2+]i response to bradykinin stimulation but did not affect the second phase of the histamine response. The biphasic nature of the histamine response, the insensitivity of the second [Ca2+]i peak to neomycin, and the independence of bradykinin and histamine responses suggest that histamine may modulate [Ca2+]i through multiple IP3 and non-IP3 pathways.