Non-Invasive Mouse Models of Post-Traumatic Osteoarthritis

SummaryAnimal models of osteoarthritis (OA) are essential tools for investigating the development of the disease on a more rapid timeline than human OA. Mice are particularly useful due to the plethora of genetically modified or inbred mouse strains available. The majority of available mouse models of OA use a joint injury or other acute insult to initiate joint degeneration, representing post-traumatic osteoarthritis (PTOA). However, no consensus exists on which injury methods are most translatable to human OA. Currently, surgical injury methods are most commonly used for studies of OA in mice; however, these methods may have confounding effects due to the surgical/invasive injury procedure itself, rather than the targeted joint injury. Non-invasive injury methods avoid this complication by mechanically inducing a joint injury externally, without breaking the skin or disrupting the joint. In this regard, non-invasive injury models may be crucial for investigating early adaptive processes initiated at the time of injury, and may be more representative of human OA in which injury is induced mechanically. A small number of non-invasive mouse models of PTOA have been described within the last few years, including intra-articular fracture of tibial subchondral bone, cyclic tibial compression loading of articular cartilage, and anterior cruciate ligament (ACL) rupture via tibial compression overload. This review describes the methods used to induce joint injury in each of these non-invasive models, and presents the findings of studies utilizing these models. Altogether, these non-invasive mouse models represent a unique and important spectrum of animal models for studying different aspects of PTOA

Mechanism of action of Ruscus extract

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Apport de la propolis dans les mécanismes de la cancérogenèse

TOULOUSE3-BU Santé-Centrale (315552105) / SudocTOULOUSE3-BU Santé-Allées (315552109) / SudocSudocFranceF

Progesterone augments the venoconstrictor effect of Ruscus without altering adrenergic reactivity

Chronic administration of oestrogen and/or progesterone does not affect adrenergic neurotransmission or contractions initiated by sympathomimetic amines in the cutaneous venous smooth muscle of the dog. However, contractions initiated by the venotropic Ruscus-extract are enhance following chronic exposure to progesterone, an affect that can be reversed by oestrogen. The contractions are mediated by an adrenergic and non-adrenergic component. The adrenergic component is enhanced by progesterone and decreased by oestrogen; the non-adrenergic component is most prominent when the serum-levels of the female steroid hormones are low.link_to_subscribed_fulltex

Effect of temperature on the responsiveness of cutaneous veins to the extract of Ruscus aculeatus

In canine cutaneous veins cooling augments and warming depresses the responses to sympathetic nerve stimulation. In these veins the extract of Ruscus aculeatus (Ruscus) causes contractions due to α-adrenergic activation. To determine the effects of temperature on the response to Ruscus, rings of canine saphenous veins were studied at 24°, 37° and 41°C. At 37°C, Ruscus caused an increase in isometric tension which was depressed by prazosin and rauwolscine. Cooling inhibited the response to Ruscus, while warming augmented it. Rauwolscine potentiated, and prazosin reversed the effect of cooling on contractions evoked by Ruscus. Prazosin reduced, and rauwolscine augmented the effect of warming. These experiments demonstrate that temperature affects the venoconstriction induced by Ruscus in an opposite fashion as that to sympathetic nerve activation, presumably because the α1-adrenergic component of the response to Ruscus predominates.link_to_subscribed_fulltex

Effect of Ruscus aculeatus on isolated canine cutaneous veins

The extract of the roots of Ruscus aculeatus causes contraction of isolated canine saphenous veins. These contractions are due to the combination of displacement of stored norepinephrine and direct activation of post junctional α-adrenergic receptors.link_to_subscribed_fulltex

The effect of the computational grid size on the prediction of a flammable cloud dispersion

The consequence analysis is used to define the extent and nature of effects caused by undesired events being of great help when quantifying the damage caused by such events. For the case of leaking of flammable and/or toxic materials, effects are analyzed for explosions, fires and toxicity. Specific models are used to analyze the spills or jets of gas or liquids, gas dispersions, explosions and fires. The central step in the analysis of consequences in such cases is to determine the concentration of the vapor cloud of hazardous substances released into the atmosphere, in space and time. With the computational advances, CFD tools are being used to simulate short and medium scale gas dispersion events, especially in scenarios where there is a complex geometry. However, the accuracy of the simulation strongly depends on diverse simulation parameters, being of particular importance the grid resolution. This study investigates the effects of the computational grid size on the prediction of a cloud dispersion considering both the accuracy and the computational cost. Experimental data is compared with the predicted values obtained by means of CFD simulation, exploring and discussing the influence of the grid size on cloud concentration the predicted values. This study contributes to optimize CFD simulation settings concerning grid definition when applied to analyses of consequences in environments with complex geometry