An investigation of the suitability of white rats for sub-orbital studies of behavior in a gravity field

Suitability of white rats for suborbital studies of behavior in gravity field

Microscopical methods for the localization of Na + , K + -ATPase

Na + , K + -ATPase plays a central role in the ionic and osmotic homeostasis of cells and in the movements of electrolytes and water across epithelial boundaries. Microscopic localization of the enzyme is, therefore, of crucial importance in establishing the subcellular routes of electrolyte flow across structurally complex and functionally polarized epithelia. Recently developed approaches to the localization of Na + , K + -ATPase are reviewed. These methods rely on different properties of the enzyme and encompass cytochemical localization of the K + -dependent nitrophenylphosphatase component of the enzyme, autoradiographic localization of tritiated ouabain binding sites, and immunocytochemical localization of the holoenzyme and of its catalytic subunit. The rationales for each of these techniques are outlined as are the critieria that have been established to validate each method. The observed localization of Na + , K + -ATPase in various tissues is discussed, particularly as it relates to putative and hypothetical mechanisms that are currently thought to mediate reabsorptive and secretory electrolyte transport.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42850/1/10735_2005_Article_BF01005056.pd

ANIMAL MODELS FOR THE STUDY OF LEISHMANIASIS IMMUNOLOGY

Leishmaniasis remains a major public health problem worldwide and is classified as Category I by the TDR/WHO, mainly due to the absence of control. Many experimental models like rodents, dogs and monkeys have been developed, each with specific features, in order to characterize the immune response to Leishmania species, but none reproduces the pathology observed in human disease. Conflicting data may arise in part because different parasite strains or species are being examined, different tissue targets (mice footpad, ear, or base of tail) are being infected, and different numbers (“low” 1×102 and “high” 1×106) of metacyclic promastigotes have been inoculated. Recently, new approaches have been proposed to provide more meaningful data regarding the host response and pathogenesis that parallels human disease. The use of sand fly saliva and low numbers of parasites in experimental infections has led to mimic natural transmission and find new molecules and immune mechanisms which should be considered when designing vaccines and control strategies. Moreover, the use of wild rodents as experimental models has been proposed as a good alternative for studying the host-pathogen relationships and for testing candidate vaccines. To date, using natural reservoirs to study Leishmania infection has been challenging because immunologic reagents for use in wild rodents are lacking. This review discusses the principal immunological findings against Leishmania infection in different animal models highlighting the importance of using experimental conditions similar to natural transmission and reservoir species as experimental models to study the immunopathology of the disease

Power Constrained Design of Multiprocessor Interconnection Networks

[6] W. J. Dally, “Performance Analysis of k-ary n-cube interconnection networks, ” IEEE Transaction

Local microstructures of Si in GaN studied by x-ray absorption spectroscopy

Si K-edge x-ray absorption spectroscopy (XAFS) has been used to study the local structure of Si dopant in GaN crystalline material. Doping concentrations NSi from 8.0 \ufffd 1016 to 4.4 \ufffd 1019 cm \ufffd 3 were investigated. It is observed that the near-edge spectra vary significantly as a function of NSi. At low concentrations the Si K-edge spectra exhibit features similar to that obtained from N K-edge measurement, while at high concentrations the near-edge spectra shape is similar to that recorded from Si3N4. We interpret the results as an indication that Si is not randomly distributed. The changes of the near-edge spectra as a function of doping level is explained as due to changes in the magnitude of Si local lattice contraction caused by the formation of various types of Si clusters. The interpretation is further supported by extended XAFS spectra analysis. A Si-induced strain-field near the surface is proposed as the main force for the cluster formation during epitaxial growth.NRC publication: Ye