RESUMO
Photosynthetic parameters were investigated in relation to light intensity (PAR and UV-B) in two Chilean Prosopis sp., Prosopis chilensis and Prosopis tamarugo in their natural habitats. The objective of this work was to compare the photosynthetic responses and to determine the degree of adaptation of both species to visible- and UV-radiation stress. One of the study sites was Refresco in the Atacama Desert, where P. tamarugo is an endemic plant and P. chilensis was introduced, and the other was Peldehue in the valley of Central Chile where only P. chilensis is present. Due to latitude, light intensity (UV-B and PAR) is higher in Refresco than in Peldehue. The parameters investigated in both species were photosystem II fluorescence, CO(2) assimilation, stomatal conductance, photosynthetic pigment composition, flavonoid absorption patterns and composition of chlorophyll-protein complexes. Fluorescence studies, CO(2) assimilation and stomatal conductance studies demonstrated that photosynthetic activity is more efficient and stable throughout the day in P. tamarugo than in P. chilensis in Refresco. Chlorophyll-protein complexes also seemed to be more stable in P. tamarugo than in P. chilensis. Photosynthetic pigment analyses indicated possible photodamage in P. chilensis trees in Refresco, but not in Peldehue. Such photodamage was absent in P. tamarugo. There was a considerable change in the flavonoid pattern between noon and afternoon hours in both species at both study sites. The physiological implications of these changes indicate that P. tamarugo is more adapted to high solar radiation than P. chilensis.
Assuntos
Clima Desértico , Fotossíntese/fisiologia , Prosopis/metabolismo , Chile , Ritmo Circadiano , Flavonoides/metabolismo , Especificidade da Espécie , Temperatura , Árvores/metabolismoRESUMO
The use of inhaled beta adrenergic agonists has assumed a greater role in the treatment of pediatric asthma as medications with a longer duration of action and more specificity for the beta 2 receptor have become available. Because of their effectiveness and safety, they are being selected as the drug of choice for maintenance therapy in children with asthma. The following study assessed compliance in asthmatic children using metaproterenol administered via a metered-dose inhaler (MDI) on a daily basis. Compliance was determined in 17 asthmatic children (aged 5 to 13 years) by measurement of cannister weight before and after a 2-week treatment period. Five children were studied for one 2-week period, while 12 children were studied for two consecutive 2-week periods. Two of five children (40%) completing 2 weeks were compliant, while only one of 12 children (8%) completing 4 weeks of the study was determined to be compliant as judged by changes in cannister weight during the treatment period. We conclude that despite the efficacy and safety of beta 2 adrenergic agonists administered via a MDI, poor compliance could potentially detract from their value as a maintenance medication in some asthmatic children.