Nonlinear Finite Element Analysis of Nanoindentation of Viral Capsids

Recent Atomic Force Microscope (AFM) nanoindentation experiments measuring mechanical response of the protein shells of viruses have provided a quantitative description of their strength and elasticity. To better understand and interpret these measurements, and to elucidate the underlying mechanisms, this paper adopts a course-grained modeling approach within the framework of three-dimensional nonlinear continuum elasticity. Homogeneous, isotropic, elastic, thick shell models are proposed for two capsids: the spherical Cowpea Chlorotic Mottle Virus (CCMV), and the ellipsocylindrical bacteriophage $\phi 29$. As analyzed by the finite element method, these models enable parametric characterization of the effects of AFM tip geometry, capsid dimensions, and capsid constitutive descriptions. The generally nonlinear force response of capsids to indentation is shown to be insensitive to constitutive details, and greatly influenced by geometry. Nonlinear stiffening and softening of the force response is dependent on the AFM tip dimensions and shell thickness. Fits of the models capture the roughly linear behavior observed in experimental measurements and result in estimates of Young's moduli of $\approx$280--360 MPa for CCMV and $\approx$4.5 GPa for $\phi 29$.Comment: 24 pages, 10 figures, submitted to Biophysical Journa

Pulmonary-function in panic disorder – evidence against the dyspnea-fear theory

De samenhang tussen somatische en psychische (dys)functie

Effects of flutter and PEP mask physiotherapy on symptoms and lung function in children with cystic fibrosis

Recently, the flutter was introduced as a new device to improve sputum expectoration. Preliminary data suggested a significant improvement in expectoration and lung function during flutter treatment in patients with cystic fibrosis (CF). The aim of the present study was to compare the effects of the flutter and the positive expiratory pressure (PEP) mask on symptoms and lung function in children with CF. In a crossover randomized study 22 patients with CF (mean age 12 yrs, range 7-17 yrs) performed physiotherapy using either the flutter or the PEP mask twice a day during two treatment periods of 2 weeks, separated by a one week wash-out period, in a random sequence. Lung function parameters (peak expiratory flow, forced vital capacity (FVC), forced expiratory volume in one second, maximal midexpiratory flow, maximal expiratory flow at 25% of FVC, thoracic gas volume, total lung capacity, residual volume/total lung capacity, airway resistance and specific airway conductance) and changes in transcutaneous oxygen haemoglobin saturation were assessed before and after the first supervised session and at the end of each treatment period. Throughout the study peak flow was measured and symptoms were scored daily. No significant changes in any lung function parameter occurred after a single session or after 2 weeks of physiotherapy with either method. There was no difference in acceptability and subjective efficacy. In conclusion, any superiority of the flutter over the positive expiratory pressure mask technique for expectoration could not be confirmed during 2 weeks of daily treatment in children with cystic fibrosis. Both methods are well accepted by children and do not change lung function. Long-term comparison of both methods, including expectoration measurements, seems to be required for further evaluation of the potential success of physiotherapy in cystic fibrosis

Educating a global workforce?

In the public rhetoric, at least, education is the answer to most, if not all, the questions raised by the global knowledge-based economy. In this chapter we begin an examination of what education promises the global workforce, and what the global workforce, and the knowledgebased economy, might reasonably ask of education. Different perspectives on the knowledgebased economy imply different constructions of ‘knowledge’. Workers are characterised within these frameworks as ‘knowledge workers’ (an elite), or, perhaps, ‘knowledgeable workers’ (the non-elite majority) and questions arise around what they are required to learn, to know, and to be able to do. The global knowledge-based economy produces profound challenges to workrelated education at every level. While these challenges manifest themselves in uniquely local ways at specific local sites, they are produced, and must be addressed, in contexts that are uncompromisingly global. If work-related education is to contribute to positive outcomes for people and for local communities we (workers, corporations, educators, researchers, policy makers, politicians and international organisations) must find new ways to pay attention to the ways in which a workforce in the knowledge-based economy can be understood to be ‘global’ as well as ‘local’, and what workers need to be able to know and be able to do to move across and within these spatial and temporal domains

The influence of smoking status on exhaled breath profiles in asthma and COPD patients

Breath analysis using eNose technology can be used to discriminate between asthma and COPD patients, but it remains unclear whether results are influenced by smoking status. We aim to study whether eNose can discriminate between ever- vs. never-smokers and smoking <24 vs. >24 h before the exhaled breath, and if smoking can be considered a confounder that influences eNose results. We performed a cross-sectional analysis in adults with asthma or chronic obstructive pulmonary disease (COPD), and healthy controls. Ever-smokers were defined as patients with current or past smoking habits. eNose measurements were performed by using the SpiroNose. The principal component (PC) described the eNose signals, and linear discriminant analysis determined if PCs classified ever-smokers vs. never-smokers and smoking <24 vs. >24 h. The area under the receiver-operator characteristic curve (AUC) assessed the accuracy of the models. We selected 593 ever-smokers (167 smoked <24 h before measurement) and 303 never-smokers and measured the exhaled breath profiles of discriminated ever- and never-smokers (AUC: 0.74; 95% CI: 0.66-0.81), and no cigarette consumption <24h (AUC 0.54, 95% CI: 0.43-0.65). In healthy controls, the eNose did not discriminate between ever or never-smokers (AUC 0.54; 95% CI: 0.49-0.60) and recent cigarette consumption (AUC 0.60; 95% CI: 0.50-0.69). The eNose could distinguish between ever and neversmokers in asthma and COPD patients, but not recent smokers. Recent smoking is not a confounding factor of eNose breath profiles

Cost-Effectiveness of Internet-Based Self-Management Compared with Usual Care in Asthma

BACKGROUND: Effectiveness of Internet-based self-management in patients with asthma has been shown, but its cost-effectiveness is unknown. We conducted a cost-effectiveness analysis of Internet-based asthma self-management compared with usual care. METHODOLOGY AND PRINCIPAL FINDINGS: Cost-effectiveness analysis alongside a randomized controlled trial, with 12 months follow-up. Patients were aged 18 to 50 year and had physician diagnosed asthma. The Internet-based self-management program involved weekly on-line monitoring of asthma control with self-treatment advice, remote Web communications, and Internet-based information. We determined quality adjusted life years (QALYs) as measured by the EuroQol-5D and costs for health care use and absenteeism. We performed a detailed cost price analysis for the primary intervention. QALYs did not statistically significantly differ between the Internet group and usual care: difference 0.024 (95% CI, -0.016 to 0.065). Costs of the Internet-based intervention were $254 (95$243 to $265) during the period of 1 year. From a societal perspective, the cost difference was$641 (95% CI, $-1957 to$3240). From a health care perspective, the cost difference was $37 (95$-874 to $950). At a willingness-to-pay of$50,000 per QALY, the probability that Internet-based self-management was cost-effective compared to usual care was 62% and 82% from a societal and health care perspective, respectively. CONCLUSIONS: Internet-based self-management of asthma can be as effective as current asthma care and costs are similar. TRIAL REGISTRATION: Current Controlled Trials ISRCTN79864465

Enhanced expression of fibroblast growth factors and receptor FGFR-1 during vascular remodeling in chronic obstructive pulmonary disease

Important characteristics of chronic obstructive pulmonary disease (COPD) include airway and vascular remodeling, the molecular mechanisms of which are poorly understood. We assessed the role of fibroblast growth factors (FGF) in pulmonary vascular remodeling by examining the expression pattern of FGF-1, FGF-2, and the FGF receptor (FGFR-1) in peripheral area of lung tissues from patients with COPD (FEV(1) < or = 75%; n = 15) and without COPD (FEV(1) > or = 85%; n = 13). Immunohistochemical staining results were evaluated by digital video image analysis as well as by manual scoring. FGF-1 and FGFR-1 were detected in vascular smooth muscle (VSM), airway smooth muscle, and airway epithelial cells. FGF-2 was localized in the cytoplasm of airway epithelium and in the nuclei of airway smooth muscle, VSM, and endothelial cells. In COPD cases, an unequivocal increase in FGF-2 expression was observed in VSM (3-fold, P = 0.001) and endothelium (2-fold, P = 0.007) of small pulmonary vessels with a luminal diameter under 200 micro m. In addition, FGFR-1 levels were elevated in the intima (1.5-fold, P = 0.05). VSM cells of large (> 200 micro m) pulmonary vessels showed increased staining for FGF-1 (1.6-fold, P < 0.03) and FGFR-1 (1.4-fold, P < 0.04) in COPD. Pulmonary vascular remodeling, assessed as the ratio of alpha-smooth muscle actin staining and vascular wall area with the lumen diameter, was increased in large vessels of patients with COPD (P = 0.007) and was inversely correlated with FEV(1) values (P < 0.007). Our results suggest an autocrine role of the FGF-FGFR-1 system in the pathogenesis of COPD-associated vascular remodeling