Treatment of impetigo with sulfonamide-urea powder

Sulfonamides can be used in the treatment of impetigo with vastly increased safety and with more effectiveness in powder rather than ointment form when combined with urea powder in a ratio of approximately three parts of sulfonamide to one of urea. Of 701 patients treated with such a mixture, 95.6 per cent were cured within a week. The only complication was local dermatitis which occurred in 0.57 per cent of patients. This compares favorably with results obtained with newer and expensive drugs which usually have the disadvantage of being used in a greasy vehicle. The low incidence of sensitivity reaction to the sulfonamide-urea powder is perhaps ascribable in part to the avoidance of a greasy vehicle.     

Quantitation of the O(2)-Dependent, CO(2)-Reversible Component of the Postillumination CO(2) Exchange Transient in Tobacco and Maize Leaves

The postillumination transient of CO₂ exchange and its relation to photorespiration has been examined in leaf discs from tobacco (Nicotiana tabacum) and maize (Zea mays). Studies of the transients observed by infrared gas analysis at 1, 21, and 43% O₂ in an open system were extended using the nonsteady state model described previously (Peterson and Ferrandino 1984 Plant Physiol 76: 976-978). Cumulative CO₂ exchange equivalents (i.e. nanomoles CO₂) versus time were derived from the analyzer responses of individual transients. In tobacco (C₃), subtraction of the time course of cumulative CO₂ exchange under photorespiratory conditions (21 or 43% O₂) from that obtained under nonphotorespiratory conditions (1% O₂) revealed the presence of an O₂-dependent and CO₂-reversible component within the first 60 seconds following darkening. This component was absent in maize (C₄) and at low external O₂:CO₂ ratios (i.e. <100) in tobacco. The size of the component in tobacco increased with net photosynthesis as irradiance was increased and was positively associated with inhibition of net photosynthesis by O₂. This relatively simple and rapid method of analysis of the transient is introduced to eliminate some uncertainties associated with estimation of photorespiration based on the maximal rate of postillumination CO₂ evolution. This method also provides a useful and complementary tool for detecting variation in photorespiration.     

Effects of CO(2) and O(2) on Photosynthesis and Growth of Autotrophic Tobacco Callus

Gas exchange measurements were made on plants from two natural populations differing in salt tolerance of Andropogon glomeratus, a C₄ nonhalophyte, to examine the effect of salinity on components responsible for differences in photosynthetic capacity. Net CO₂ uptake and stomatal conductance decreased with increasing salinity in both populations, but to a greater extent in the inland (nontolerant) population. The intercellular CO₂ concentrations increased with increasing salinity in the inland population, but decreased in the marsh (tolerant) population. Water use efficiency decreased as salinity increased in the inland population, and remained unchanged in the marsh population. Carboxylation efficiency decreased and CO₂ compensation points increased with increasing salinity in both populations, but to a lesser extent in the marsh population. Carboxylation efficiencies were higher with 2% relative to 21% atmospheric O₂ in salt stressed plants, suggesting that a decrease in the carboxylation:oxygenation ratio of ribulose 1,5-bisphosphate carboxylase/oxygenase was partly responsible for the decrease in photosynthetic capacity. Populational differences in photosynthetic capacity were the result of greater salinity-induced changes in carboxylation efficiency in the inland population, and not due to differences in the stomatal limitation to CO₂ diffusion.     

Partitioning of Noncyclic Photosynthetic Electron Transport to O(2)-Dependent Dissipative Processes as Probed by Fluorescence and CO(2) Exchange

The partitioning of noncyclic photosynthetic electron transport between net fixation of CO₂ and collective O₂-dependent, dissipative processes such as photorespiration has been examined in intact leaf tissue from Nicotiana tabacum. The method involves simultaneous application of CO₂ exchange and pulse modulated fluorescence measurements. As either irradiance or CO₂ concentration is varied at 1% O₂ (i.e. absence of significant O₂-dependent electron flow), the quantum efficiency of PSII electron transport (_se) with CO₂ as the terminal acceptor is a linear function of the ratio of photochemical:nonphotochemical fluorescence quenching coefficients (i.e. q_Q:q_NP). When the ambient O₂ concentration is raised to 20.5% or 42% the q_Q:q_NP is assumed to predict the quantum efficiency of total noncyclic electron transport (′_se). A factor which represents the proportion of electron flow diverted to the aforementioned dissipative processes is calculated as (′_se − _se)/′_se where _se is now the observed quantum efficiency of electron transport in support of net fixation of CO₂. Examination of changes in electron allocation with CO₂ and O₂ concentration and irradiance at 25°C provides a test of the applicability of the Rubisco model to photosynthesis in vivo.     

Characterization of a meta-Fluorotyrosine-Tolerant Cell Culture of Eschscholtzia californica Cham

A cell line of Eschscholtzia californica selected for meta-fluorotyrosine (MFT) tolerance was found to have 10-fold increased levels of phenylalanine and tyrosine compared to the parent line, while most other amino acids were only increased 2-fold. Tracer experiments with shikimic acid in the presence of MFT showed that the biosynthesis of the aromatic amino acids was not impaired in the tolerant line. Feeding experiments with phenylalanine, tyrosine, or shikimic acid also revealed a reduced turnover of the pools of the aromatic amino acids in the variant. Thus undisturbed de novo biosynthesis of the aromatic amino acids and dilution of toxic effects of MFT by the enlarged pool sizes seemed to be the main reason for the acquired tolerance. Despite the enlarged availability of the precursor tyrosine, formation of the benzophenanthridine alkaloids was enhanced neither in the growth nor in the production medium.