No abstract is provided for this article.
The bronchial epithelium has a number of mechanical functions including mucociliary clearance and protection against noxious agents. However, there is increasing evidence that it is a metabolically active tissue that may modulate the function of the underlying smooth muscle by metabolism and regulation of mediators and the production of relaxant, constrictor, or chemotactic factors. It is therefore possible that the epithelial abnormalities observed in asthmatics may lead, via several different mechanisms, to increased bronchial hyperresponsiveness (figure 2), which is a fundamental feature of asthma. However, it may not be necessary to invoke structural damage to explain derangement of epithelial function. It is possible that functional biochemical abnormalities may be present in epithelial cells, thereby producing bronchial hyperresponsiveness in the absence of histologic abnormalities. Further studies with bronchial epithelium, similar to those with vascular endothelium, are needed to clarify its role in the pathogenesis of asthma.
Many of the principal concepts that underpin current metallic structural design codes were developed on the basis of bilinear (elastic, perfectly-plastic) material behaviour; such material behaviour lends itself to the concept of section classification. The continuous strength method represents an alternative treatment to cross-section classification, which is based on a continuous relationship between slenderness and (inelastic) local buckling and a rational exploitation of strain hardening. The development and application of the continuous strength method to structural steel design is described herein. Materials that exhibit a high degree of nonlinearity and strain hardening, such as aluminium, stainless steel and some high-strength steels, fit less appropriately into the framework of cross-section classification, and generally benefit to a greater extent from the continuous strength method. The method provides better agreement with test results in comparison to existing design codes, and offers increases in member resistance and a reduction in scatter of the prediction. An additional benefit of the proposed approach is that cross-section deformation capacity is explicitly determined in the calculations, thus enabling a more sophisticated and informed assessment of ductility supply and demand. Further developments to the method are under way.
Purpose: To assess, by a European registry trial, the clinical event rate in patients with discrete stenotic lesions of coronary arteries (de novo or restenotic) in single or multiple vessels (native or bypass grafts) treated with β-radiation. Methods and materials: Between April 1999 and September 2000, 1098 consecutive patients treated in 46 centers in Europe and the Middle East with the Novoste Beta-Cath System were included in Registry Novoste (RENO). Results: Six-month follow-up data were obtained for 1085 patients. Of 1174 target lesions, 94.1% were located in native vessels and 5.9% in a bypass graft; 17.7% were de novo lesions, 4.1% were restenotic, and 77.7% were in-stent restenotic lesions. Intravascular brachytherapy was technically successful in 95.9% of lesions. Multisegmental irradiation, using a manual pullback stepping maneuver to treat longer lesions, was used in 16.3% of the procedures. The in-hospital rate of major adverse cardiac events was 1.8%. At 6 months, the rate was 18.7%. Angiographic follow-up was available for 70.4% of the patients. Nonocclusive restenosis was seen in 18.8% and total occlusion in 5.7% of patients. A combined end point for late (30–180 days) definitive or suspected target vessel closure was reached in 5.4%, but with only 2% of clinical events. Multivariate analysis was performed for major adverse cardiac events and late thrombosis. Conclusion: Data obtained from the multicenter RENO registry study, derived from a large cohort of unselected consecutive patients, suggest that the good results of recent randomized controlled clinical trials can be replicated in routine clinical practice.
No abstract is provided for this article.