Examining the Evidence for Chytridiomycosis in Threatened Amphibian Species

Extinction risks are increasing for amphibians due to rising threats and minimal conservation efforts. Nearly one quarter of all threatened/extinct amphibians in the IUCN Red List is purportedly at risk from the disease chytridiomycosis. However, a closer look at the data reveals that Batrachochytrium dendrobatidis (the causal agent) has been identified and confirmed to cause clinical disease in only 14% of these species. Primary literature surveys confirm these findings; ruling out major discrepancies between Red List assessments and real-time science. Despite widespread interest in chytridiomycosis, little progress has been made between assessment years to acquire evidence for the role of chytridiomycosis in species-specific amphibian declines. Instead, assessment teams invoke the precautionary principle when listing chytridiomycosis as a threat. Precaution is valuable when dealing with the world's most threatened taxa, however scientific research is needed to distinguish between real and predicted threats in order to better prioritize conservation efforts. Fast paced, cost effective, in situ research to confirm or rule out chytridiomycosis in species currently hypothesized to be threatened by the disease would be a step in the right direction. Ultimately, determining the manner in which amphibian conservation resources are utilized is a conversation for the greater conservation community that we hope to stimulate here

Copy number variation in Williams-Beuren syndrome: suitable diagnostic strategy for developing countries

<p>Abstract</p> <p>Background</p> <p>Williams-Beuren syndrome (WBS; OMIM 194050) is caused by a hemizygous contiguous gene microdeletion at 7q11.23. Supravalvular aortic stenosis (SVAS), mental retardation, and overfriendliness comprise typical symptoms of WBS. Although fluorescence in situ hybridization (FISH) is considered the gold standard technique, the microsatellite DNA markers and multiplex ligation-dependent probe amplification (MLPA) could be used for to confirm the diagnosis of WBS.</p> <p>Results</p> <p>We have evaluated a total cohort of 88 patients with a suspicion clinical diagnosis of WBS using a collection of five markers (D7S1870, D7S489, D7S613, D7S2476, and D7S489_A) and a commercial MLPA kit (P029). The microdeletion was present in 64 (72.7%) patients and absent in 24 (27.3%) patients. The parental origin of deletion was maternal in 36 of 64 patients (56.3%) paternal in 28 of 64 patients (43.7%). The deletion size was 1.55 Mb in 57 of 64 patients (89.1%) and 1.84 Mb in 7 of 64 patients (10.9%). The results were concordant using both techniques, except for four patients whose microsatellite markers were uninformative. There were no clinical differences in relation to either the size or parental origin of the deletion.</p> <p>Conclusion</p> <p>MLPA was considered a faster and more economical method in a single assay, whereas the microsatellite markers could determine both the size and parental origin of the deletion in WBS. The microsatellite marker and MLPA techniques are effective in deletion detection in WBS, and both methods provide a useful diagnostic strategy mainly for developing countries.</p

Métabolisme énergétique des personnes âgées [Energy metabolism in the elderly].

The energy metabolism in elderly subjects is discussed on the basis of previous analyses of the influence of age on the three components of energy expenditure in man: basal metabolic rate, thermogenesis and physical activity. All three components are diminished in elderly people. We conclude that the modifications of body composition, in particular the age-related loss of lean body mass, result in decreased basal metabolic rate and probably also a blunted diet-induced thermogenesis. Moreover we emphasize that the decrease in physical activity observed in elderly people is the most likely causal factor

Simulations of a Therapeutic Proton Beam with FLUKA Monte Carlo Code and Varian Eclipse Proton Planning Software

The sharp dose deposition from protons in a medium has some clear advantageous aspects for use in cancer treatment. When charged particles, for instance protons, traverse matter, most of their energy are deposited at the end of their range, causing a sharp peak, the Bragg peak, at a depth determined by the proton range in the medium. This range is a function of the initial proton energy and of the characteristics of the traversed medium. The purpose of this project has been to apply Monte Carlo software to simulate a proton beam resembling a therapeutic beam, and to study the interactions of this beam in phantoms of various design. The simulations were produced with FLUKA Monte Carlo code version 2011 2b. Further the purpose has been to apply Varian Eclipse proton planning (version 11) software to create treatment plans on similar phantoms, in order to study the differences between a time-effective, clinically optimized tool and an accurate, yet time consuming, Monte Carlo simulation tool. A fundamental criteria for a therapeutic beam is that the beam must have the ability to deliver a homogeneous dose to an extended volume. To meet this criteria, the energy of the applied protons must be spread out in order to create a plateau of dose covering the target volume, which is the tumour with some specified margins. This implies that an otherwise monoenergetic beam needs to be energy modulated in order to produce a weighted energy spectrum, resulting in a spread-out Bragg peak (SOBP). In this project, two different approaches were followed in order to obtain a dose deposition with a flat dose plateau at the desired depth. By (1) passively modulating the beam range by inserting material into the simulated beamline, which is the equivalent of the use of a range modifier positioned in the beamline, and by (2) actively modulating the proton energy from the beam source. The resulting dose distributions from these two approaches showed that the dose falloff at the distal part of the target volume was sharper with the active energy modulation approach than when passively using material to modulate the beam energy. The final goal of this project was obtained by the use of a commercial treatment planning system to produce simple treatment plans, and further; to compare the dose profiles to similar treatment plans created with a Monte Carlo simulated beam and geometry. The overall agreement between the two calculation methods were adequate, especially with respect to dose coverage within the defined target volume. However, when introducing different materials such as bone, air and aluminium into the geometry, the differences between the two methods became apparent and it illustrates the tentative limitations of a fast, clinical optimized, dose planning tool compared with a more accurate and detailed, hence tentatively slower, Monte Carlo simulation tool