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Pit membranes in bordered pits between neighbouring vessels play a major role in the entry of air-water menisci from an embolised vessel into a water-filled vessel (i.e., air-seeding). Here, we investigate intervessel pit membrane thickness (TPM) and embolism resistance (P50, i.e., the water potential corresponding to 50% loss of hydraulic conductivity) across a broad range of woody angiosperm species. Data on TPM and double intervessel wall thickness (TVW) were compiled based on electron and light microscopy. Fresh material that was directly fixated for transmission electron microscopy (TEM) was investigated for 71 species, while non-fresh samples were frozen, stored in alcohol, or air dried prior to TEM preparation for an additional 60 species. TPM and P50 were based on novel observations and literature. A strong correlation between TPM and P50 was found for measurements based on freshly fixated material (r = 0.78, P <0.01, n = 37), and between TPM and TVW (r = 0.79, P <0.01, n = 59), while a slightly weaker relationship occurred between TVW and P50 (r = 0.40, P <0.01, n = 34). However, non-fresh samples showed no correlation between TPM and P50, and between TPM and TVW. Intervessel pit membranes in non-fresh samples were c.28% thinner and more electron dense than fresh samples. Our findings demonstrate that TPM measured on freshly fixated material provides one of the strongest wood anatomical correlates of droughtinduced embolism resistance in angiosperms. Assuming that cellulose microfibrils show an equal spatial density, TPM is suggested to affect the length and the shape of intervessel pit membrane pores, but not the actual pore size. Moreover, the shrinking effect observed for TPM after dehydration and frost is associated with an increase in microfibril density and porosity, which may provide a functional explanation for embolism fatigue. [ABSTRACT FROM AUTHOR]

Background: Intermittent asthma in children is often treated only with short-action β-agonists; however, most cases do not control totally the disease. Objective: To assess the effect of salbutamol, as rescue drug, associated with other drugs for controlling asthma. Patients and methods: Fifty children, from 1 to 14 years old, with intermittent asthma, who were assisted at Out-Patient Consultation of Pediatric Allergy, Children Hospital Eva Samano de Lopez Mateos, from January to October, 2004, were selected. Treatment consisted of the following regimens: 1) salbutamol, 2) salbutamol and budesonide, 3) salbutamol and montelukast and 4) salbutamol, budesonide and montelukast. After three months of treatment asthma control degree was measured by disappearing of symptoms (total control) or decrease of symptoms in more than 70% a week (partial control). Results: A better control was observed in patients receiving budesonide (inhaled steroid) and salbutamol (p < 0.05), compared to those who were not treated with inhaled steroid. This regimen achieved in 44% the disappearing of symptoms (total control) and in 56% reduced the symptoms in more than 70% (partial control). Group receiving salbutamol, budesonide and montelukast reached a total and partial control in 47.1% and 52.9%, respectively. Conclusions: Inhaled steroids are a choice to better control and avoid the progression of intermittent asthma. The use of new progression markers of asthma should be evaluated, in order to determine which children may receive early inhaled steroids and how long. [ABSTRACT FROM AUTHOR]

Background: Intermittent asthma in children is often treated only with short-action beta-agonists; however, most cases do not control totally the disease., Objective: To assess the effect of salbutamol, as rescue drug, associated with other drugs for controlling asthma., Patients and Methods: Fifty children, from 1 to 14 years old, with intermittent asthma, who were assisted at Out-Patient Consultation of Pediatric Allergy, Children Hospital Eva Samano de Lopez Mateos, from January to October, 2004, were selected. Treatment consisted of the following regimens: (1) salbutamol, (2) salbutamol and budesonide, (3) salbutamol and montelukast and (4) salbutamol, budesonide and montelukast. After three months of treatment asthma control degree was measured by disappearing of symptoms (total control) or decrease of symptoms in more than 70% a week (partial control)., Results: A better control was observed in patients receiving budesonide (inhaled steroid) and salbutamol (p < 0.05), compared to those who were not treated with inhaled steroid. This regimen achieved in 44% the disappearing of symptoms (total control) and in 56% reduced the symptoms in more than 70% (partial control). Group receiving salbutamol, budesonide and montelukast reached a total and partial control in 47.1% and 52.9%, respectively., Conclusions: Inhaled steroids are a choice to better control and avoid the progression of intermittent asthma. The use of new progression markers of asthma should be evaluated, in order to determine which children may receive early inhaled steroids and how long.