Developing and using fast shear wave elastography to quantify physiologically-relevant tendon forces.

Direct quantification of physiologically-relevant tendon forces can be used in a wide range of clinical applications. However, tendon forces have usually been estimated either indirectly by computational models or invasively using force transducers, and direct non-invasive measurement of forces remains a big challenge. The aim of this study was to investigate the feasibility of using Shear Wave Elastography (SWE) for quantifying human tendon forces at physiological levels. An experimental protocol was developed to measure Shear Wave Speed (SWS) and tensile force in a human patellar tendon using SWE and conventional tensile testing to quantify the correlation between SWS and load. The SWE system was customised to allow imaging of fast shear waves expected in human tendons under physiological loading which is outside the normal range of the existing SWE systems. SWS increased from 10.8 m/s to 36.1 m/s with the increasing tensile load from 8 N to 935 N and a strong linear correlation between SWS and load (r = 0.99, p < 0.01) was observed. The findings in this study suggest that SWE can be used as a potential non-invasive method for direct quantification of physiologically-relevant tendon forces, as well as for validating the estimated forces from other methods such as computational models.

Trajectory-Based Skill Learning Using Generalized Cylinders.

In this article, we introduce Trajectory Learning using Generalized Cylinders (TLGC), a novel trajectory-based skill learning approach from human demonstrations. To model a demonstrated skill, TLGC uses a Generalized Cylinder-a geometric representation composed of an arbitrary space curve called the spine and a surface with smoothly varying cross-sections. Our approach is the first application of Generalized Cylinders to manipulation, and its geometric representation offers several key features: it identifies and extracts the implicit characteristics and boundaries of the skill by encoding the demonstration space, it supports for generation of multiple skill reproductions maintaining those characteristics, the constructed model can generalize the skill to unforeseen situations through trajectory editing techniques, our approach also allows for obstacle avoidance and interactive human refinement of the resulting model through kinesthetic correction. We validate our approach through a set of real-world experiments with both a Jaco 6-DOF and a Sawyer 7-DOF robotic arm.

Feasibility of using mixtures of silicone elastomers and silicone oils to model the mechanical behaviour of biological tissues.

Mixtures of silicone elastomer and silicone oil were prepared and the values of their Young's moduli, E, determined in compression. The mixtures had volume fractions, [Formula: see text], of silicone oil in the range of 0-0.73. Measurements were made, under displacement control, for strain rates, [Formula: see text], in the range of 0.04-3.85 s(-1). The behaviour of [Formula: see text] as a function of [Formula: see text] and [Formula: see text] was investigated using a response surface model. The effects of the two variables were independent for the silicones used in this investigation. As a result, the dependence of E values (measured in MPa) on [Formula: see text] and [Formula: see text] (s(-1)) could be represented by [Formula: see text]. This means that these silicones can be mixed to give materials with E values in the range of about 0.02-0.57 MPa, which includes E values for many biological tissues. Thus, the mixtures can be used for making models for training health-care professionals and may be useful in some research applications as model tissues that do not exhibit biological variability.

Anticancer activity of Sargassum oligocystum water extract against human cancer cell lines.

BACKGROUND AND OBJECTIVES: Antitumor drug resistance and side effects of antitumor compounds are the most common problems in medicine. Therefore, finding new antitumor agents with low side effects could be interesting. This study was designed to assay antitumor activity of the extract from brown alga Sargassum oligocystum, gathered from Persian Gulf seashore, against K562 and Daudi human cancer cell lines. MATERIALS AND METHODS: The research was performed as an in vitro study. The effect of the alga extract on proliferation of cell lines were measured by two methods: MTT assay and trypan blue exclusion test. RESULTS AND CONCLUSION: The most effective antitumor activity has been shown at concentrations 500 microg/ml and 400 microg/ml of the alga extract against Daudi and K562 cell lines, respectively. The results showed that the extracts of brown alga Sargassum oligocystum have remarkable antitumor activity against K562 and Daudi cell lines. It is justified to be suggested for further research such as algal extract fractionation and purification and in vivo studies in order to formulate natural compounds with antitumor activities.

Secondary hyperparathyroidism is associated with higher mortality in men with moderate to severe chronic kidney disease.

Secondary hyperparathyroidism is associated with mortality in patients undergoing maintenance dialysis treatment. We studied 515 male US veterans with chronic kidney disease, who were not yet on dialysis, to see what outcomes were associated with secondary hyperparathyroidism in this population. Relationships between intact parathyroid hormone levels and all-cause mortality along with the composite of mortality or incidence of dialysis were measured in unadjusted and adjusted Cox models for case-mix and laboratory variables. Elevated parathyroid hormone levels above the upper limit compared to the lower limit of the normal range were significantly associated with mortality after adjustments. Higher intact parathyroid hormone levels in the upper limit of normal were significantly associated with higher mortality overall and showed similar trends in subgroups of patients with stage 3 and stage 4-5 chronic kidney disease and with higher and lower serum calcium and phosphorus levels. Similar associations were found with the composite outcome of mortality or dialysis. Our study shows that secondary hyperparathyroidism is independently associated with higher mortality in patients with chronic kidney disease but not yet on dialysis.