To discern whether stage-specific resistance of Schistosoma mansoni to praziquantel occurs in vitro, we determined minimal effective concentrations (MECs) of drug needed to increase motor activity, produce contraction and/or paralysis, and cause tegumental vesiculation of developmental stages from day 0 to day 42 of S. mansoni. Recovery of these stages from exposure to praziquantel in vitro was also evaluated. MECs of praziquantel inducing increased motor activity and muscular contraction or paralysis or both were 0.005-0.01 micrograms/ml, irrespective of the stage examined. However, day-3 lung forms were more resistant than other stages when either drug-induced tegumental vesiculation (MEC, 1 microgram/ml) or recovery from drug exposure was tested. Three-day infections with S. mansoni in CF1 mice were also less responsive to praziquantel treatment than were infections of shorter or longer duration. The concentrations of praziquantel and periods of drug exposure causing gross tegumental damage to S. mansoni in vitro correlated with the peak serum levels and time course of unchanged praziquantel associated with reduction of worm burden in vivo. Thus, stage-specific resistance of S. mansoni to praziquantel does occur in vitro and correlates better with the tegumental than the muscular action of the drug.
Abstract. The strongest observed solar magnetic fields are found in sunspot umbrae and associated light bridges. We investigate systematic measurements of approximately 32 000 sunspot groups observed from 1917 through 2004 using data from Mt. Wilson, Potsdam, Rome and Crimea observatories. Isolated observations from other observatories are also included. Corrections to Mt. Wilson measurements are required and applied. We found 55 groups (0.2%) with at least one sunspot with one magnetic field measurement of at least 4000 G including five measurements of at least 5000 G and one spot with a record field of 6100 G. Although typical strong-field spots are large and show complex structure in white light, others are simple in form. Sometimes the strongest fields are in light bridges that separate opposite polarity umbras. The distribution of strongest measured fields above 3 kG appears to be continuous, following a steep power law with exponent about −9.5. The observed upper limit of 5 -6 kG is consistent with the idea that an umbral field has a more or less coherent structure down to some depth and then fragments. We find that odd-numbered sunspot cycles usually contain about 30% more total sunspot groups but 60% fewer >3 kG spots than preceding even-numbered cycles.
This paper describes a thorough reevaluation of the procedures for reducing the data acquired at the Mt. Wilson Observatory synoptic program of solar observations at the 150-foot tower. We also describe a new program of acquiring as many scans per day as possible of the solar magnetic and velocity fields. We give a new fitting formula which removes the background velocity field from each scan. An important new feature of our reduction algorithm is our treatment of the limb shift which permits time variation in this function. We identify the difference between the limb shift along the north-south axis and the east-west axis as potentially being a result of meridional circulation. Our analysis interprets the time variation in the east-west limb shift as being the result of changes in a vertical component of the meridional circulation.The performance of the system improved in 1982 as a result of the installation of a new exit slit assembly. The amplitude of the limb shift variations found prior to 1982 is larger than is easily explained with simple ideas of meridional circulation. However, we have not been able to firmly identify instrumental causes for the variations although small changes in the band-pass of the exit slit assembly could have contributed.We have established a correlation between the observed stray light in the system and a component of the velocity field which is antisymmetric with respect to the solar central meridian. We remove this stray light effect by adding an additional term to the fitting function.Finally, we show that the inclusion of the above improvements allows us to study the torsional oscillations at high latitude using a procedure which can retain the longitude dependent information about the velocity pattern.
Previous studies from this laboratory have shown that certain factors regulating the resistance of mice to naturally induced Bacillus enteritidis infection are inborn (1). The new data to be presented show that, under the experimental conditions, resistance to B. enteritidis and resistance to St. Louis encephalitis virus" are inherited in a similar and relatively definite manner but independently. Materials and TechniqueThe general technique employed in this work has been described (1). It was pointed out that following early experiments on small numbers of mice from the Rockefeller Institute breeding stock, a special breeding colony was started in 1929 with 600 of these animals which were tested and proved free of infection. The diet was changed from a bread and milk ration, producing mortalities following injection of mouse typhoid bacilli generally high (70 per cent), but fluctuating with season, to one producing low and more stable mortalities (37 ± 1.6 per cent).Finally, B. enteritidis rather than B. aertrycke was used as the test agent. These different experimental conditions, reflected in the different levels of mortality of the two control groups, permit early and later data to be compared'qualitatively (1) but not ~luantitatively (Hill, 2).The breeding stock was established and has remained free of the infections under investigation and others as determined by continued testing. At the outset it would have been preferable in selecting for possible resistant strains to proceed as with the susceptibles and choose for breeding, unexposed siblings of tested litters rather than the survivors themselves. This error was committed on but a single occasion, at the commencement of the experiment, however, and the rigid measures employed for detecting infected animals were known to be effective. Only the uninfected survivors were mated and the resulting litters tested, found to be uninfected, and then placed in the breeding room. Subsequently, no survivors have been used for breeding.The mouse colony is subjected to continued search for infectious agents. The occasional sickly mouse is sacrificed and tested for the presence of pathogenic 261
This study based on longitudinal Zeeman effect magnetograms and spectral line scans investigates the dependence of solar surface magnetic fields on the spectral line used and the way the line is sampled in order to estimate the magnetic flux emerging above the solar atmosphere and penetrating to the corona from magnetograms of the Mt. Wilson 150-foot tower synoptic program (MWO). We have compared the synoptic program \lambda5250\AA line of Fe I to the line of Fe I at \lambda5233\AA since this latter line has a broad shape with a profile that is nearly linear over a large portion of its wings. The present study uses five pairs of sampling points on the $\lambda5233$\AA line. We recommend adoption of the field determined with a line bisector method with a sampling point as close as possible to the line core as the best estimate of the emergent photospheric flux. The combination of the line profile measurements and the cross-correlation of fields measured simultaneously with \lambda5250\AA and \lambda5233\AA yields a formula for the scale factor 1/\delta that multiplies the MWO synoptic magnetic fields. The new calibration shows that magnetic fields measured by the MDI system on the SOHO spacecraft are equal to 0.619+/-0.018 times the true value at a center-to-limb position 30 deg. Berger and Lites (2003) found this factor to be 0.64+/-0.013 based on a comparison the the Advanced Stokes Polarimeter.Comment: Accepted by Solar Physic
We publish here rotation results from Doppler velocity measurements made at Mount Wilson over a period of more than 14 years. Altogether data from 188 rotations are presented. These results are displayed in various tables and figures. Measurements of scattered light along with its effect on the measured rotation rate are shown.
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