Reappraising the theme of breeding systems in Echinococcus: is outcrossing a rare phenomenon?

Selfing has been considered the most common mode of reproduction in Echinococcus flatworms. However, population genetic studies on the asexual larval stage involving nuclear co-dominant markers have not always revealed significant heterozygote deficiencies - the expected outcome of a regularly and highly inbred population. In this study, we analysed the genetic structure of Echinococcus granulosus sensu lato populations from Southern Brazil during their adult (sexual) stage using 1 mitochondrial and 1 nuclear marker (cox 1 and mdh, respectively). We show that parasite genetic differentiation is largest among definitive hosts (domestic dogs) from different farms, suggesting that transmission is mostly maintained within a farm. Moreover, we show that heterozygote deficiencies are not significant, and we suggest that outbreeding is the most common mode of reproduction of the parasite in that regio

Theoretical Directional and Modulated Rates for Direct SUSY Dark Matter Detection

Exotic dark matter together with the vacuum energy (cosmological constant) seem to dominate in the flat Universe. Thus direct dark matter detection is central to particle physics and cosmology. Supersymmetry provides a natural dark matter candidate, the lightest supersymmetric particle (LSP). Furthermore from the knowledge of the density and velocity distribution of the LSP, the quark substructure of the nucleon and the nuclear structure (form factor and/or spin response function), one is able to evaluate the event rate for LSP-nucleus elastic scattering. The thus obtained event rates are, however, very low. So it is imperative to exploit the two signatures of the reaction, namely the modulation effect, i.e. the dependence of the event rate on the Earth's motion, and the directional asymmetry, i.e. the dependence of the rate on the the relative angle between the direction of the recoiling nucleus and the sun's velocity. These two signatures are studied in this paper employing various velocity distributions and a supersymmetric model with universal boundary conditions at large tan(beta).Comment: 11 LATEX pages, 1 table and 4 ps figures included. Paper presented in DARK2002, Fourth Heidelberg International Conference on Dark Matter in Astro- and Particle Physics, Cape Town, South Africa, 4-9 February, 2002, to appear in the proceedings (to be published by Springer Verlag

Femoral revision knee Arthroplasty with Metaphyseal sleeves: the use of a stem is not mandatory of a structural point of view

Purpose Metaphyseal sleeves are an option for patients with severe metaphyseal bony defects requiring TKA revision. Although sleeves are usually used with stems, little is known about the exact contribution/need of the stem for the initial sleeve-bone interface stability, particularly in the femur, if the intramedullary canal is deformed or bowed. It is hypothesised that diaphyseal-stem addition increases the sleeve-femur interface stability and the strain-shielding effect on the metaphyseal femur relatively to the stemless condition. Material and methods Synthetic-femur was used to measure cortex strain behaviour and implant cortex micromotions for three techniques: only femoral-component, stemless-sleeve and stemmed-sleeve. Paired t-tests were performed to evaluate the statistical significance of the difference between mean principal strains and implant-cortex micromotions. Finite-element models were developed to assess the cancellous-bone strain behaviour and sleeve-bone interface micromotions; these models were validated against the measurements. Results Cortex strains are reduced significantly (p<0.05) in 83% of strain gauges on stemmed-sleeve, which compares with 33% in stemless condition. Both techniques presented a cancellous bone strain reduction of 50% at the distal region and an increase of nearly four times at the sleeve proximal region relative to the model only with the femoral component. Both techniques presented sleeve-bone micromotions amplitude below 50-150μm, suitable for bone ingrowth. Conclusions The use of a supplemental diaphyseal-stem potentiates the risk of cortex bone resorption compared with the stemless-sleeve condition; however, the stem is not vital for increasing the initial sleeve-bone stability and has a minor effect on the cancellous-bone strain behaviour. Of a purely structural point view, appears that the use of a diaphyseal-femoral-stem with the metaphyseal sleeve is not mandatory in the revision TKA which is particularly relevant in cases where the use of stems is impracticable.publishe

The cross on rings performed by an Olympic champion

The cross is a key skill in Male Artistic Gymnastics rings routines. However, few researches were found about this skill. There is knowledge about the forces needed to perform the cross, or about muscles activation, separately. The aim of this paper was to accomplish a comprehensive research about the biomechanics of cross on rings, in order to obtain a descriptive model about this skill. Therefore, the currently Olympic champion on rings event volunteered in this research. He performed three crosses with the usual apparatus in his training gym. The measurement methods were combined: One digital video camera, one strain gauge in each cable and surface electromyography of nine right shoulder muscles were used. Statistical analyses were performed by parametric and non parametric tests and descriptive statistics. Symmetry values were calculated for shoulder angles and cables of right and left side. Coefficient of variation of muscle activation and co contraction were verified. Within gymnast variability was calculated using biological coefficient of variation (BCV), discretely for kinematic measures. Low variability values of shoulder angles and cable forces were verified and low values of asymmetry as well. Muscle activation varied according to muscle function, while co-contraction values were different among trials. These results pointed out the characteristics of the cross performed by an elite gymnast. Knowledge about the characteristics of cross can inform coaches, practitioners and clinicians how a successful skill should be presented

Study protocol subacromial impingement syndrome: the identification of pathophysiologic mechanisms (SISTIM)

<p>Abstract</p> <p>Background</p> <p>The Subacromial Impingement Syndrome (SIS) is the most common diagnosed disorder of the shoulder in primary health care, but its aetiology is unclear. Conservative treatment regimes focus at reduction of subacromial inflammatory reactions or pathologic scapulohumeral motion patterns (<it>intrinsic </it>aetiology). Long-lasting symptoms are often treated with surgery, which is focused at enlarging the subacromial space by resection of the anterior part of the acromion (based on <it>extrinsic </it>aetiology). Despite that acromionplasty is in the top-10 of orthopaedic surgical procedures, there is no consensus on its indications and reported results are variable (successful in 48-90%). We hypothesize that the aetiology of SIS, i.e. an increase in subacromial pressure or decrease of subacromial space, is multi-factorial. SIS can be the consequence of pathologic scapulohumeral motion patterns leading to humerus cranialisation, anatomical variations of the scapula and the humerus (e.g. hooked acromion), a subacromial inflammatory reaction (e.g. due to overuse or micro-trauma), or adjoining pathology (e.g. osteoarthritis in the acromion-clavicular-joint with subacromial osteophytes).</p> <p>We believe patients should be treated according to their predominant etiological mechanism(s). Therefore, the objective of our study is to identify and discriminate etiological mechanisms occurring in SIS patients, in order to develop tailored diagnostic and therapeutic strategies.</p> <p>Methods</p> <p>In this cross-sectional descriptive study, applied clinical and experimental methods to identify intrinsic and extrinsic etiologic mechanisms comprise: MRI-arthrography (eligibility criteria, cuff status, 3D-segmented bony contours); 3D-motion tracking (scapulohumeral rhythm, arm range of motion, dynamic subacromial volume assessment by combining the 3D bony contours and 3D-kinematics); EMG (adductor co-activation) and dynamometry instrumented shoulder radiographs during arm tasks (force and muscle activation controlled acromiohumeral translation assessments); Clinical phenotyping (Constant Score, DASH, WORC, and SF-36 scores).</p> <p>Discussion</p> <p>By relating anatomic properties, kinematics and muscle dynamics to subacromial volume, we expect to identify one or more predominant pathophysiological mechanisms in every SIS patient. These differences in underlying mechanisms are a reflection of the variations in symptoms, clinical scores and outcomes reported in literature. More insight in these mechanisms is necessary in order to optimize future diagnostic and treatment strategies for patients with SIS symptoms.</p> <p>Trial registration</p> <p>Dutch Trial Registry (Nederlands Trial Register) <a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2283">NTR2283</a>.</p

Present state and future perspectives of using pluripotent stem cells in toxicology research

The use of novel drugs and chemicals requires reliable data on their potential toxic effects on humans. Current test systems are mainly based on animals or in vitro–cultured animal-derived cells and do not or not sufficiently mirror the situation in humans. Therefore, in vitro models based on human pluripotent stem cells (hPSCs) have become an attractive alternative. The article summarizes the characteristics of pluripotent stem cells, including embryonic carcinoma and embryonic germ cells, and discusses the potential of pluripotent stem cells for safety pharmacology and toxicology. Special attention is directed to the potential application of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) for the assessment of developmental toxicology as well as cardio- and hepatotoxicology. With respect to embryotoxicology, recent achievements of the embryonic stem cell test (EST) are described and current limitations as well as prospects of embryotoxicity studies using pluripotent stem cells are discussed. Furthermore, recent efforts to establish hPSC-based cell models for testing cardio- and hepatotoxicity are presented. In this context, methods for differentiation and selection of cardiac and hepatic cells from hPSCs are summarized, requirements and implications with respect to the use of these cells in safety pharmacology and toxicology are presented, and future challenges and perspectives of using hPSCs are discussed