Tantalum oxide/carbon nanotubes composite coatings on titanium, and their functionalization with organophosphonic molecular films:A high quality scaffold for hydroxyapatite growth

peer reviewedNowadays, titanium is a very commonly used biomaterial for the preparation of orthopedic and dental implants. Its excellent mechanical and biochemical bulk properties are nevertheless counterbalanced by its propensity to long term degradation in physiological conditions and its weak osseointegrative capacities. In this context, surface modifications can significantly hinder titanium weaknesses. The approach considered in this work relies on the preparation of thin composite coatings based on tantalum oxide and carbon nanotubes by sol–gel process. Tantalum is particularly interesting for its high biocompatibility and bioactivity, as well as its strong resistance to bio-corrosion. Carbon nanotubes are exploited to reinforce the compactness and homogeneity of the coatings, and can act as a favorable factor to strengthen the interaction with bone components by biomimicry. The composite layers are further modified with specific organophosphonic acid molecular films, able to chemically bind the tantalum oxide surface and improve the hydroxyapatite formation process. The characteristics and the qualities of these hybrid inorganic/organic coatings are evaluated by XPS, SEM, TEM, peeling tests, contact angle measurements, and electrochemical characterizations (free potential, polarization curves)

Late Holocene palaeohydrology of lake Afourgagh (Middle-Atlas, Morocco) from deposit geometry and facies

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Ergotism with acute limb ischemia, provoked by HIV protease inhibitors interaction with ergotamine, rescued by multisite transluminal balloon angioplasty

International audienceAcute limb ischemia induced by arterial vasospasm remains an exceptional situation, favoured by the use of arterial vasoconstrictors. The risk of these substances is largely underestimated in the general population, especially with the co-administration of strong cytochrome inhibitors like human immunodeficiency virus (HIV) protease inhibitors. A 33-year-old woman, who used to take dihydroergotamine for orthostatic hypotension, was prescribed a post-exposure HIV prophylaxis including lopinavir and ritonavir. One day later, she presented an acute bilateral limb ischemia with a sudden pain in both calves, initially while walking and then at rest with bilateral ischemic toes. Angiography confirmed diffuse arterial vasospasm of the lower limb arteries. A first-line therapy with isosorbide dinitrate and amlodipine was ineffective, with rapid clinical worsening. A combination of intra-arterial injections and intra-venous infusions of vasodilators, transluminal balloon angioplasty and bilateral 4-Compartment fasciotomies permitted rapid improvement and finally resulted in both lower limbs rescue. This case and literature review illustrate ergotism due to ergotamine overdose after taking HIV protease inhibitors. It also demonstrates the benefit of an interventional procedure besides medical therapy with vasodilators in severe arterial vasospasm. All along the lower limb arterial tree, transluminal balloon angioplasty restored the blood flow, without vasospasm recurrence. CONCLUSION: In case of ergotism with acute lower limbs ischemia, combining medical vasodilator therapy with interventional procedure can restore the arterial blood flow, thus allowing to save lower limbs