91 research outputs found
Airway resistance at maximum inhalation as a marker of asthma and airway hyperresponsiveness
<p>Abstract</p> <p>Background</p> <p>Asthmatics exhibit reduced airway dilation at maximal inspiration, likely due to structural differences in airway walls and/or functional differences in airway smooth muscle, factors that may also increase airway responsiveness to bronchoconstricting stimuli. The goal of this study was to test the hypothesis that the minimal airway resistance achievable during a maximal inspiration (R<sub>min</sub>) is abnormally elevated in subjects with airway hyperresponsiveness.</p> <p>Methods</p> <p>The R<sub>min </sub>was measured in 34 nonasthmatic and 35 asthmatic subjects using forced oscillations at 8 Hz. R<sub>min </sub>and spirometric indices were measured before and after bronchodilation (albuterol) and bronchoconstriction (methacholine). A preliminary study of 84 healthy subjects first established height dependence of baseline R<sub>min </sub>values.</p> <p>Results</p> <p>Asthmatics had a higher baseline R<sub>min </sub>% predicted than nonasthmatic subjects (134 ± 33 vs. 109 ± 19 % predicted, p = 0.0004). Sensitivity-specificity analysis using receiver operating characteristic curves indicated that baseline R<sub>min </sub>was able to identify subjects with airway hyperresponsiveness (PC<sub>20 </sub>< 16 mg/mL) better than most spirometric indices (Area under curve = 0.85, 0.78, and 0.87 for R<sub>min </sub>% predicted, FEV<sub>1 </sub>% predicted, and FEF<sub>25-75 </sub>% predicted, respectively). Also, 80% of the subjects with baseline R<sub>min </sub>< 100% predicted did not have airway hyperresponsiveness while 100% of subjects with R<sub>min </sub>> 145% predicted had hyperresponsive airways, regardless of clinical classification as asthmatic or nonasthmatic.</p> <p>Conclusions</p> <p>These findings suggest that baseline R<sub>min</sub>, a measurement that is easier to perform than spirometry, performs as well as or better than standard spirometric indices in distinguishing subjects with airway hyperresponsiveness from those without hyperresponsive airways. The relationship of baseline R<sub>min </sub>to asthma and airway hyperresponsiveness likely reflects a causal relation between conditions that stiffen airway walls and hyperresponsiveness. In conjunction with symptom history, R<sub>min </sub>could provide a clinically useful tool for assessing asthma and monitoring response to treatment.</p
Imbibition in Disordered Media
The physics of liquids in porous media gives rise to many interesting
phenomena, including imbibition where a viscous fluid displaces a less viscous
one. Here we discuss the theoretical and experimental progress made in recent
years in this field. The emphasis is on an interfacial description, akin to the
focus of a statistical physics approach. Coarse-grained equations of motion
have been recently presented in the literature. These contain terms that take
into account the pertinent features of imbibition: non-locality and the
quenched noise that arises from the random environment, fluctuations of the
fluid flow and capillary forces. The theoretical progress has highlighted the
presence of intrinsic length-scales that invalidate scale invariance often
assumed to be present in kinetic roughening processes such as that of a
two-phase boundary in liquid penetration. Another important fact is that the
macroscopic fluid flow, the kinetic roughening properties, and the effective
noise in the problem are all coupled. Many possible deviations from simple
scaling behaviour exist, and we outline the experimental evidence. Finally,
prospects for further work, both theoretical and experimental, are discussed.Comment: Review article, to appear in Advances in Physics, 53 pages LaTe
Compliance with herpes zoster vaccination in young and adult individuals in two regions of Italy
Background: The purpose of this work was to explore the knowledge and acceptance of Varicella Zoster Virus (VZV)-
Herpes Zoster (HZ) vaccination in the general Italian population, where the HZ vaccine has not yet been distributed,
using a prevalence study of subjects from two regions in Italy.
Methods: A group of 3,173 individuals were interviewed using a questionnaire. The youngest age group (≤ 20 year)
was composed of students interviewed at university. The middle age group (21-40 years) and the older age group (≥
41 years) were interviewed by general practitioners in their office.
Results: In both regions, the majority of subjects had been infected with varicella, and only 165 (5.2%) subjects
reported receiving the VZV vaccination. Regarding HZ, 2,749 (86.6%) individuals stated that they knew of the virus and
2,233 (70%) were willing to be vaccinated against HZ. The majority of people willing to be vaccinated were in the
middle and older age groups (36.6% and 44.7%, respectively).
Conclusion: Compliance versus vaccination results were satisfactory and probably, with the upcoming availability of
the HZ vaccine in Italy, adults will be favourably disposed towards vaccination
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