Biological responses of ligament and tendon graft-derived fibroblasts to clinical levels of cyclic strain

Anterior Cruciate Ligament (ACL) is one of the major ligaments in the knee. ACL injury is the partial or complete tear of the ACL usually as a consequence of a traumatic sports related injury. ACL injury commonly affects athletes in the late adolescence and are usually more common in females than males. Factors such as metabolic response, cellular crosstalk among tissues and sex differences are not fully understood. Therefore, an increased comprehension of the biology of ACL injury and healing is required. Management of ACL injuries is typically achieved by surgical stabilization of the knee. For this, arthroscopic ACL reconstruction with different tendon autografts is the gold standard technique. Additionally, ligament repair by suturing the torn ends of the ACL is an alternative procedure. Although current surgical treatment, is generally successful, ACL graft and repair healing biology needs to be further explored to decrease failure rates. Moreover, whether a specific activity level would in turn affect the healing process is still not known. Several in vitro and in vivo preclinical models have been developed to explore current ACL injury and healing biology. Among these, large animals offer the advantage to be similar to the human. The preferred model is the spontaneous onset of ACL injury, commonly found in dogs. In both species, extracellular matrix (ECM) remodeling driven by cellular responses to load can influence disease, as well as response to treatment. However, most in vitro models do not include the multiple cell types in the joint or the mechanical environment that modulates their responses. Consequently, we aimed to evaluate the metabolic responses of fibroblasts obtained from canine intraarticular tissues potentially involved in ACL injury as well as tendon grafts commonly used for ACL reconstruction subjected to varying levels of mechanical stress in a monolayer culture. We hypothesized that fibroblasts from these tissues would produce significantly different levels of inflammatory and remodeling biomarkers in response to a spectrum of cyclic strains in vitro. We were able to demonstrate that ACL surrounding tissues are an important source of inflammatory and degradative biomarkers, and that metabolic responses of tendon graft fibroblasts are strain and tissue dependent. Moreover, male canine tendon fibroblasts seem to increase degradative responses while females tend to increase inflammatory responses when stimulated with different strain magnitudes. Also, synoviocytes are an important source of inflammation and human intraarticular tissue fibroblasts and tendon graft-derived fibroblasts have variable responses to stress but is not differentially affected by sex. Consequently, further studies are required to elucidate complex regulation mechanisms in both canines and humans.Includes bibliographical reference

Engaging with linguistic justice through objectives-based learning and independent research

How can we foster the learner investment required for difficult, reflexive discussions about linguistic justice? We address this question through our efforts as instructors in a general education course on language in the US. To help students reflect on their own positionality within systems of oppression, we nurtured student-instructor relationships where students felt respected, valued, and capable of success using objectives-based assessment strategies and structured independent research projects. Students’ positive feedback and focus on LEARNING over simply earning a grade demonstrate the efficacy of our approach

Role of histamine in the inhibitory effects of phycocyanin in experimental models of allergic inflammatory response.

It has recently been reported that phycocyanin, a biliprotein found in the blue-green microalgae Spirulina, exerts anti-inflammatory effects in some animal models of inflammation. Taking into account these findings, we decided to elucidate whether phycocyanin might exert also inhibitory effects in the induced allergic inflammatory response and on histamine release from isolated rat mast cells. In in vivo experiments, phycocyanin (100, 200 and 300mg/kg post-orally (p.o.)) was administered 1 h before the challenge with 1 microg of ovalbumin (OA) in the ear of mice previously sensitized with OA. One hour later, myeloperoxidase activity and ear edema were assessed. Phycocyanin significantly reduced both parameters. In separate experiments, phycocyanin (100 and 200 mg/kg p.o.) also reduced the blue spot area induced by intradermal injections of histamine, and the histamine releaser compound 48/80 in rat skin. In concordance with the former results, phycocyanin also significantly reduced histamine release induced by compound 48/80 from isolated peritoneal rat mast cells. The inhibitory effects of phycocyanin were dose dependent. Taken together, our results suggest that inhibition of allergic inflammatory response by phycocyanin is mediated, at least in part, by inhibition of histamine release from mast cells

Field-Tuning of the electron and hole populations in the ruthenate Bi_3Ru_3O_11

Experiments on the Hall coefficient R_H and heat capactity C reveal an unusual, compensated electronic ground state in the ruthenate Bi_3Ru_3O_11. At low temperature T, R_H decreases linearly with magnetic field |H| for fields larger than the field scale set by the Zeeman energy. The results suggest that the electron and hole populations are tuned by H in opposite directions via coupling of the spins to the field. As T is decreased below 5 K, the curve C(T)/T vs. T^2 shows an anomalous flattening consistent with a rapidly growing Sommerfeld parameter \gamma(T). We discuss shifts of the electron and hole chemical potentials by H to interpret the observed behavior of R_H.Comment: 5 pages, 6 figures, reference adde

New pycnodontiform fishes (Actinopterygii, Neopterygii) from the Early Cretaceous of the Argentinian Patagonia

Here we describe new pycnodontiform fish material recovered from the marine Agrio Formation (lower Valanginian–lower Hauterivian) of the Neuquén Province in the south-western of Patagonia, Argentina. The new material include an incomplete skull and an incomplete prearticular dentition. The incomplete skull consists of some dermal and endochondral elements as well as dental remains and represents a new large-sized gyrodontid that is referred to a new species, Gyrodus huiliches. Gyrodus huiliches sp. nov. is characterized by a unique combination of tooth crown ornamentations and tooth shape separating it easily from all known Gyrodus species. The incomplete prearticular dentition shows a tooth arrangement and sculpture that resembles that of “Macromesodon” agrioensis –the previously only known pycnodontiform in the area. This allows revising this species, which was based on an isolated vomerine dentition and which we refer to a new genus, Tranawuen. The new Patagonian fishes reported here expand the knowledge of South American pycnodontiforms. We hypothesize that meanwhile the new Patagonian genus – Tranawuen– diverged from Gyrodus after it migrated into the eastern Pacific through the Hispanic Corridor during the Late Jurassic, the new species –Gyrodus huiliches– most likely diverged from a Central or South American species of Gyrodus. Both represent the youngest gyrodontid records and simultaneously the southernmost Early Cretaceous occurrences of pycnodontiform fishes.Fil: Gouiric Cavalli, Soledad. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; ArgentinaFil: Remirez, Mariano Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Kriwet, Jürgen. University of Vienna; Austri

Active variable geometry suspension for cars

This thesis investigates the characteristics and performance of a new type of active suspension for cars through modelling, simulation, control design and experimental testing. The Series Active Variable Geometry Suspension (SAVGS) concept is first put in context by reviewing the history and current trends in automotive suspensions. Its potential is then critically evaluated and work is carried out to maximise its performance for various suspension functions. A multi-model multi-software modelling and simulation approach is followed throughout the thesis in order to cross-check and substantiate simulation results in the absence of experimental data. The simpler linear models are used to inform the selection of suitable parameter sets for the case studies, to synthesise control systems and to qualitatively validate the more complex, nonlinear multi-body models. The latter are developed as a platform to virtually test the system and its control algorithms. When possible, these tests are based on standard open-loop test manoeuvres and on standardised external disturbances. The SAVGS-retrofitted suspension displays a very nonlinear behaviour, which is at the same time a liability and an opportunity from the point of view of control. Nevertheless, different linear control techniques are effectively applied to improve various suspension functions: PIDs are applied to the lower frequency suspension functions such as mitigation of chassis attitude motions, and the H∞ framework is applied to the higher frequency suspension functions such as comfort and road holding enhancement. In all cases, a cascade control approach is employed, and mechanisms are implemented to ensure that physical and design actuator constraints are always respected. This thesis also covers the design and construction of a quarter-car experimental test rig facility. Step-by-step recommendations for its refinement as well as a testing plan are also outlined.Open Acces

Vertical changes in shoreline morphology at intra-parasequence scale

It is commonly assumed in the high-resolution sequence stratigraphic analysis ofshallow-marine deposits (e.g., deltaic and shoreface settings) that the depositionalconditions of the system remain relatively constant during the transit of a shorelinethat would eventually produce a single parasequence. However, based on thedetailed sedimentary and architectural analysis of upper-shoreface and foreshorestrata of two Early Cretaceous shoreface-shelf parasequences (Neuquén Basin,Argentina), it was possible to document a vertical change through the stratigraphyfrom deposits representing wave-dominated barred shorelines to depositsinterpreted as representing a non-barred morphology. The presence of a welldefinedlimit between trough cross-bedded sandstones in the upper shoreface andplanar laminated sandstones in the foreshore (and the presence of a surf diastem)characterize the development of barred shoreline conditions. Instead, planarlamination is ubiquitous within non-barred deposits, where trough cross-beddingis restricted to the bottomsets of the large-scale inclined beds that characterize thisarchitectural style. Thickness, sediment composition and reconstructed shorelinetrajectory also seemingly change vertically within the investigated parasequences.Collectively, these pieces of evidence suggest that the vertical transition frombarred to non-barred deposits at this intra-parasequence scale could be relatedto wave-climate variations and the sequence-stratigraphic context. Specifically,changes in the prevailing wave behavior from dissipative to reflective conditionscould be a feasible explanation for the morphological transformation of coastalsystems through tens of thousands to hundreds of thousands years.Fil: Isla, Manuel Fermín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Remirez, Mariano Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Schwarz, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Veiga, Gonzalo Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentin

Teleoperation and Contact Detection of a Waterjet-Actuated Soft Continuum Manipulator for Low-Cost Gastroscopy

Gastric cancer is the third leading cause of cancer deaths worldwide, with most new cases occurring in low and middle income countries, where access to screening programs is hindered by the high cost of conventional endoscopy. The waterjet-actuated HydroJet endoscopic platform was developed as a low-cost, disposable alternative for inspection of the gastric cavity in low-resource settings. In this work, we present a teleoperation scheme and contact detection algorithm that work together to enable intuitive teleoperation of the HydroJet within the confined space of the stomach. Using a geometrically accurate stomach model and realistic anatomical inspection targets, we demonstrate that, using these methods, a novice user can complete a gastroscopy in approximately the same amount of time with the HydroJet as with a conventional endoscope

Online Disturbance Estimation for Improving Kinematic Accuracy in Continuum Manipulators

Continuum manipulators are flexible robots which undergo continuous deformation as they are actuated. To describe the elastic deformation of such robots, kinematic models have been developed and successfully applied to a large variety of designs and to various levels of constitutive stiffness. Independent of the design, kinematic models need to be calibrated to best describe the deformation of the manipulator. However, even after calibration, unmodeled effects such as friction, nonlinear elastic and/or spatially varying material properties as well as manufacturing imprecision reduce the accuracy of these models. In this letter, we present a method for improving the accuracy of kinematic models of continuum manipulators through the incorporation of orientation sensor feedback. We achieve this through the use of a “disturbance wrench,” which is used to compensate for these unmodeled effects, and is continuously estimated based on orientation sensor feedback as the robot moves through its workspace. The presented method is applied to the HydroJet, a waterjet-actuated soft continuum manipulator, and shows an average of 40% reduction in root mean square position and orientation error in the two most common types of kinematic models for continuum manipulators, a Cosserat rod model and a pseudo-rigid body model