497 research outputs found
Cephalexin: In Vitro and in Vivo Studies
Cephalexin, a derivative of cephalosporin C, produces high serum and urine concentrations after oral administration. In addition, it shows good activity in vitro against most gram-positive and some gram-negative organisms. This study reports the in vitro susceptibility to cephalexin of a series of clinical isolates, the serum levels and urine concentrations in human volunteers and the results of its use in infections due to susceptible organisms. Results of in vitro susceptibility testing reveal that cephalexin was effective against most strains of the gram-positive organisms tested — group A streptococci, pneumococci, and staphylococci — although the MIC\u27s are higher than those found for cephaloridine and ampicillin, with the one exception being penicillinase producing staphylococcus against which ampicillin is ineffective. Cephalexin is effective against most strains of indole-negative proteus, Klebsiella and E. coli, but all strains of enterobacter show resistance. Forty-seven patients with a variety of clinical illnesses were treated with cephalexin. Five of 14 patients with urinary tract infections were cured and nine had a remission followed by a bacteriologic relapse. All patients with soft tissue infection were cured as were nine of 12 patients with pneumonia. Of the three patients with pneumonia who were not cured, one improved, while two were classified as treatment failures. Similarly, 11 of 12 patients with streptococcal pharyngitis had a clinical remission, although in three, the organism was isolated after therapy. One patient with an associated coagulase-positive staphylococci cultured from the pharynx failed to respond to treatment
Use of Lysolecithin-Permeabilized Infected-Cell Extracts to Investigate thein VitroBiochemical Phenotypes of Poxvirus ts Mutations Altered in Viral Transcription Activity
AbstractLysolecithin permeabilization of vaccinia virus-infected cells was employed to prepare extracts that support faithful transcription initiationin vitroon plasmids possessing early, intermediate, and late viral gene promoters. Conditions which optimize transcription from each promoter were defined. Thein vitrosystem was used to investigate the multifunctional viral mRNA capping enzyme, which also functions as the viral early gene transcription termination factor (VTF) and a viral intermediate gene transcription initiation factor. A low level of signal-dependent termination of early gene transcription was observedin vitrowhich could be elevated by the addition of pure mRNA capping enzyme. VTF-dependent transcription termination was found to be restricted to templates that possessed an early promoter. This restriction mimics that observedin vivoand demonstrates that transcription termination is limited to RNA polymerase molecules that recognize early rather than intermediate or late gene promoters. Extracts prepared from cells infected at the nonpermissive temperature with a virus containing a ts mutation in gene D12L, which encodes the small subunit of VTF, are incapable of supporting both early gene transcription termination and intermediate gene transcription initiation. Both activities are restored upon addition of the purified wild-type mRNA capping enzyme
Modeling Kepler transit light curves as false positives: Rejection of blend scenarios for Kepler-9, and validation of Kepler-9d, a super-Earth-size planet in a multiple system
Light curves from the Kepler Mission contain valuable information on the
nature of the phenomena producing the transit-like signals. To assist in
exploring the possibility that they are due to an astrophysical false positive,
we describe a procedure (BLENDER) to model the photometry in terms of a "blend"
rather than a planet orbiting a star. A blend may consist of a background or
foreground eclipsing binary (or star-planet pair) whose eclipses are attenuated
by the light of the candidate and possibly other stars within the photometric
aperture. We apply BLENDER to the case of Kepler-9, a target harboring two
previously confirmed Saturn-size planets (Kepler-9b and Kepler-9c) showing
transit timing variations, and an additional shallower signal with a 1.59-day
period suggesting the presence of a super-Earth-size planet. Using BLENDER
together with constraints from other follow-up observations we are able to rule
out all blends for the two deeper signals, and provide independent validation
of their planetary nature. For the shallower signal we rule out a large
fraction of the false positives that might mimic the transits. The false alarm
rate for remaining blends depends in part (and inversely) on the unknown
frequency of small-size planets. Based on several realistic estimates of this
frequency we conclude with very high confidence that this small signal is due
to a super-Earth-size planet (Kepler-9d) in a multiple system, rather than a
false positive. The radius is determined to be 1.64 (+0.19/-0.14) R(Earth), and
current spectroscopic observations are as yet insufficient to establish its
mass.Comment: 20 pages in emulateapj format, including 8 tables and 16 figures. To
appear in ApJ, 1 January 2010. Accepted versio
A First Comparison of Kepler Planet Candidates in Single and Multiple Systems
In this letter we present an overview of the rich population of systems with
multiple candidate transiting planets found in the first four months of Kepler
data. The census of multiples includes 115 targets that show 2 candidate
planets, 45 with 3, 8 with 4, and 1 each with 5 and 6, for a total of 170
systems with 408 candidates. When compared to the 827 systems with only one
candidate, the multiples account for 17 percent of the total number of systems,
and a third of all the planet candidates. We compare the characteristics of
candidates found in multiples with those found in singles. False positives due
to eclipsing binaries are much less common for the multiples, as expected.
Singles and multiples are both dominated by planets smaller than Neptune; 69
+2/-3 percent for singles and 86 +2/-5 percent for multiples. This result, that
systems with multiple transiting planets are less likely to include a
transiting giant planet, suggests that close-in giant planets tend to disrupt
the orbital inclinations of small planets in flat systems, or maybe even to
prevent the formation of such systems in the first place.Comment: 13 pages, 13 figures, submitted to ApJ Letter
Inhibition of microbial biofuel production in drought-stressed switchgrass hydrolysate
Additional file 2. Maps of significant gene ontology terms for chemical genomics data. Untreated biomass composition. Detailed hydrolysate composition
Multiple Environmental Stressors Induce Complex Transcriptomic Responses Indicative of Phenotypic Outcomes in Western Fence Lizard
Background
The health and resilience of species in natural environments is increasingly challenged by complex anthropogenic stressor combinations including climate change, habitat encroachment, and chemical contamination. To better understand impacts of these stressors we examined the individual- and combined-stressor impacts of malaria infection, food limitation, and 2,4,6-trinitrotoluene (TNT) exposures on gene expression in livers of Western fence lizards (WFL, Sceloporus occidentalis) using custom WFL transcriptome-based microarrays.
Results
Computational analysis including annotation enrichment and correlation analysis identified putative functional mechanisms linking transcript expression and toxicological phenotypes. TNT exposure increased transcript expression for genes involved in erythropoiesis, potentially in response to TNT-induced anemia and/or methemoglobinemia and caused dose-specific effects on genes involved in lipid and overall energy metabolism consistent with a hormesis response of growth stimulation at low doses and adverse decreases in lizard growth at high doses. Functional enrichment results were indicative of inhibited potential for lipid mobilization and catabolism in TNT exposures which corresponded with increased inguinal fat weights and was suggestive of a decreased overall energy budget. Malaria infection elicited enriched expression of multiple immune-related functions likely corresponding to increased white blood cell (WBC) counts. Food limitation alone enriched functions related to cellular energy production and decreased expression of immune responses consistent with a decrease in WBC levels.
Conclusions
Despite these findings, the lizards demonstrated immune resilience to malaria infection under food limitation with transcriptional results indicating a fully competent immune response to malaria, even under bio-energetic constraints. Interestingly, both TNT and malaria individually increased transcriptional expression of immune-related genes and increased overall WBC concentrations in blood; responses that were retained in the TNT x malaria combined exposure. The results demonstrate complex and sometimes unexpected responses to multiple stressors where the lizards displayed remarkable resiliency to the stressor combinations investigated
TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844
Data from the newly-commissioned \textit{Transiting Exoplanet Survey
Satellite} (TESS) has revealed a "hot Earth" around LHS 3844, an M dwarf
located 15 pc away. The planet has a radius of and
orbits the star every 11 hours. Although the existence of an atmosphere around
such a strongly irradiated planet is questionable, the star is bright enough
(, ) for this possibility to be investigated with transit and
occultation spectroscopy. The star's brightness and the planet's short period
will also facilitate the measurement of the planet's mass through Doppler
spectroscopy.Comment: 10 pages, 4 figures. Submitted to ApJ Letters. This letter makes use
of the TESS Alert data, which is currently in a beta test phase, using data
from the pipelines at the TESS Science Office and at the TESS Science
Processing Operations Cente
TESS Discovery of a Transiting Super-Earth in the Mensae System
We report the detection of a transiting planet around Mensae (HD
39091), using data from the Transiting Exoplanet Survey Satellite (TESS). The
solar-type host star is unusually bright (V=5.7) and was already known to host
a Jovian planet on a highly eccentric, 5.7-year orbit. The newly discovered
planet has a size of and an orbital period of 6.27
days. Radial-velocity data from the HARPS and AAT/UCLES archives also displays
a 6.27-day periodicity, confirming the existence of the planet and leading to a
mass determination of . The star's proximity and
brightness will facilitate further investigations, such as atmospheric
spectroscopy, asteroseismology, the Rossiter--McLaughlin effect, astrometry,
and direct imaging.Comment: Accepted for publication ApJ Letters. This letter makes use of the
TESS Alert data, which is currently in a beta test phase. The discovery light
curve is included in a table inside the arxiv submissio
Knowledge translation of the American College of Emergency Physicians’ clinical policy on syncope using computerized clinical decision support
Accurate and reliable quantification of total microalgal fuel potential as fatty acid methyl esters by in situ transesterification
In the context of algal biofuels, lipids, or better aliphatic chains of the fatty acids, are perhaps the most important constituents of algal biomass. Accurate quantification of lipids and their respective fuel yield is crucial for comparison of algal strains and growth conditions and for process monitoring. As an alternative to traditional solvent-based lipid extraction procedures, we have developed a robust whole-biomass in situ transesterification procedure for quantification of algal lipids (as fatty acid methyl esters, FAMEs) that (a) can be carried out on a small scale (using 4–7 mg of biomass), (b) is applicable to a range of different species, (c) consists of a single-step reaction, (d) is robust over a range of different temperature and time combinations, and (e) tolerant to at least 50% water in the biomass. Unlike gravimetric lipid quantification, which can over- or underestimate the lipid content, whole biomass transesterification reflects the true potential fuel yield of algal biomass. We report here on the comparison of the yield of FAMEs by using different catalysts and catalyst combinations, with the acid catalyst HCl providing a consistently high level of conversion of fatty acids with a precision of 1.9% relative standard deviation. We investigate the influence of reaction time, temperature, and biomass water content on the measured FAME content and profile for 4 different samples of algae (replete and deplete Chlorella vulgaris, replete Phaeodactylum tricornutum, and replete Nannochloropsis sp.). We conclude by demonstrating a full mass balance closure of all fatty acids around a traditional lipid extraction process
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