Patterns of mitochondrial DNA instability in Brassica campestris cultured cells

We previously showed that the mitochondrial DNA (mtDNA) of a Brassica campestris callus culture had undergone extensive rearrangements (i.e. large inversions and a duplication) relative to DNA of the control plant [54]. In this study we observed that after continued growth, the mtDNA of this culture continues to change, with rearranged forms amplifying and diminishing to varying proportions. Strikingly similar changes were detected in the mtDNA profiles of a variety of other long- and short-term callus and cell suspension lines. However, the proportions of parental (‘unrearranged’) and novel (‘rearranged’) forms varied in different cultured cell mtDNAs. To address the source of this heterogeneity, we compared the mtDNA organization of 28 individual plants from the parental seed stock. With the exception of one plant containing high levels of a novel plasmid-like mtDNA molecule, no significant variation was detected among individual plants and therefore source plant variation is unlikely to have contributed to the diversity of mitochondrial genomes observed in cultured cells. The source of this culture-induced heterogeneity was also investigated in 16 clones derived from single protoplasts. A mixed population of unrearranged and rearranged mtDNA molecules was apprent in each protoclone, suggesting that the observed heterogeneity in various cultures might reflect the genomic composition of each individual cell; however, the induction of an intercellular heterogeneity subsequent to the protoplast isolation was not tested and therefore cannot be ruled out. The results of this study support our earlier model that the rapid structural alteration of B. campestris mtDNA in vitro results from preferential amplification and reassortment of minor pre-existing forms of the genome rather than de novo rearrangement. Infrequent recombination between short dispersed repeated elements is proposed as the underlying mechanism for the formation of these minor mtDNA molecules.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43428/1/11103_2004_Article_BF00017914.pd

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

SIMULATION OF GROUND-WATER FLOW TO ASSESS THE EFFECTS OF PUMPING AND CANAL LINING ON THE HYDROLOGIC REGIME OF THE MESILLA BASIN: Dona Ana County, New Mexico & El Paso County, Texas

This study, which is to provide information to a settlement over the rights to water resources in the Mesilla Basin, uses a groundwater model to estimate how pumping in the basin affects the hydrologic regime.Research and development was supported in part by the Elephant Butte Irrigation District. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the Elephant Butte Irrigation District.This title from the Hydrology & Water Resources Technical Reports collection is made available by the Department of Hydrology & Atmospheric Sciences and the University Libraries, University of Arizona. If you have questions about titles in this collection, please contact [email protected]

Manipulation of corticosteroid release from a transiently supersaturated topical metered dose aerosol using a residual miscible co-solvent

Purpose. The creation of supersaturation transiently after application overcomes the issue of drug instability. However, if the solvents used to drive supersaturation evaporate too quickly, drug recrystallisation or rapid film drying can occur which will inhibit drug release. As such the effects of a residual solvent, poly(ethylene glycol) 400 (PEG), on the release, mobility and supersaturation kinetics of a transiently supersaturated formulation were studied. Materials and Methods. Metered dose aerosol (MDA) formulations consisting of hydrofluoroalkane 134a, ethanol, poly(vinyl pyrrolidone) K90, beclomethasone dipropionate (BDP), and 0%, 5% or 10% w/w PEG were prepared in canisters sealed with metered dose valves and tested for release and adhesion over time. Results. The addition of 10% PEG to the MDA formulation resulted in a significant reduction (p < 0.05) in steady state drug release rate (230.4 +/- 17.3 mu g/cm(2)/h for 0% PEG MDA, 83.6 +/- 4.9 mu g/cm(2)/h for 10% PEG MDA). The presence of PEG caused a delay in dose depletion (2 h for 0% PEG MDA versus 4 h for 10% PEG), retarded supersaturation kinetics and increased film drying time. Conclusion. Whilst equivalent amounts of BDP were released, the residual solvent altered the drug release profile to achieve more constant delivery.Peer reviewe

Brain Activations During Correct and False Recognitions of Visual Stimuli: Implications for Eyewitness Decisions on an fMRI Study Using a Film Paradigm

Kühnel S, Mertens M, Woermann FG, Markowitsch HJ. Brain Activations During Correct and False Recognitions of Visual Stimuli: Implications for Eyewitness Decisions on an fMRI Study Using a Film Paradigm. BRAIN IMAGING AND BEHAVIOR. 2008;2(3):163-176.Human behavior strongly relies on the visual storage of events. Unfortunately, the sense of sight is susceptible to numerous distortions and misidentifications. Our study investigated the possibility of applying neuroimaging methods for verification of eyewitness reports. We developed a film paradigm and investigated three related picture sets in a recognition task using functional magnetic resonance imaging (fMRI). For each picture subjects were instructed to make a known-unknown decision. Behavioral results showed false recognitions for nearly half of the presented stimuli. The fMRI results revealed distinct activations for correct and false recognitions. The orbito-frontal cortex could be distinguished as a key region for processing imagined and distorted information resulting in correct rejection of unknown material. Otherwise, false recognitions of unknown material highlighted surprising activation within the posterior cingulate gyrus indicating the subjects' strain to match unknown information to that known. The results are discussed in terms of current false memory research