Modification of morphological characters and cuticular compounds in worker ants Leptothorax nylanderi induced by endoparasites Anomotaenia brevis.

Anomotaenia brevis (Cestoda, Cyclophyllidea) induces major changes in the morphological characters of the host ant, Leptothorax nylanderi (Hymenoptera, Formicidae): alteration of pigmentation, lowering of adult mean size, reduction of legs, eyes and head, enlargement of petiole. The presence of parasites in adult ants also modifies the quantity of cuticular compounds but not their quality. The parasite induces some changes in the synthesis/release of 13 cuticular hydrocarbons. The higher the number of parasites within a worker, the larger the quantitative changes in four cuticular hydrocarbons in comparison with normal ants. Such modifications (morphology, chemistry, behaviour) may explain the partial intolerance exerted by normal workers against the parasitized ants.

Chemical modification of titanium surfaces for covalent attachment of biological molecules.

The surface of implantable biomaterials is in direct contact with the host tissue and plays a critical role in determining biocompatibility. In order to improve the integration of implants, it is desirable to control interfacial reactions such that nonspecific adsorption of proteins is minimized and tissue-healing phenomena can be controlled. In this regard, our goal has been do develop a method to functionalize oxidized titanium surfaces by the covalent immobilization of bioactive organic molecules. Titanium first was chemically treated with a mixture of sulfuric acid and hydrogen peroxide to eliminate surface contaminants and to produce a consistent and reproducible titanium oxide surface layer. An intermediary aminoalkylsilane spacer molecule was then covalently linked to the oxide layer, followed by the covalent binding of either alkaline phosphatase or albumin to the free terminal NH2 groups using glutaraldehyde as a coupling agent. Surface analyses following coating procedures consisted of X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Enzymatic activity of coupled alkaline phosphatase was assayed colorimetrically, and surface coverage by bound albumin was evaluated by SEM visualization of colloidal gold immunolabeling. Our results indicate that the linkage of the aminoalkylsilane to the oxidized surface is stable and that bound proteins such alkaline phosphatase and albumin retain their enzymatic activity and antigenicity, respectively. The density of immunolabeling for albumin suggests that the binding and surface coverage obtained is in excess of what would be expected for inducing biological activity. In conclusion, this method offers the possibility of covalently linking selected molecules with known biological activity to oxidized titanium surfaces in order to guide and promote the tissue healing that occurs during implant integration in bone and soft tissues.

Pelvic pseudotumoral calcium pyrophosphate dihydrate deposition: an ultrastructural study.

We analyzed large periarticular calcifications of the hips and pubis in a woman with diffuse primary chondrocalcinosis, symptomatic in the knees. Serial articular and periarticular biopsies were obtained during surgery for osteoporotic hip fracture. Histologic examination showed diffuse nonbirefringent clumps in red alizarin stained cartilage, capsula and tendon. Scanning electron microscopy with microanalysis indicated a calcium/phosphorus atomic ratio of about 1. Transmission electron microscopy, electron diffraction and Raman spectroscopy assessed calcium pyrophosphate dihydrate (CPPD) in cartilage, synovia, capsula, tendon and muscle. The cause of these hard to observe, bulky CPPD periarticular deposits, which resembled basic calcium phosphate on radiography, is still unclear.

[Air pouch model in the rat for evaluating articular phlogogenic capacity of ceramics]. / Le modèle de poche à air du rat pour l'évaluation du pouvoir phlogogène articulaire de céramiques.

We used the joint air pouch model in rats to study the inflammation induced by three types of calcium phosphate biomaterial: 10 mg of synthetic hydroxyapatite (HA), a sintered ceramic made of hydrooxyapatite and phosphate tricalcium (BCP), and calcium phosphate in the form of a fibre extracted from a vitro-ceramic material (VPC). Histological examination was made after 48 hours. The most intense inflammatory reaction was observed with BCP: the thickness of the superficial stratified layer of synoviocyte-like cells doubled, interstitial fibrosis occurred and neovascularization with polymorphous inflammatory infiltration was seen. HA led to the same, though less intense, type of reaction. Discrete, variable, localized inflammation was seen with VPC and was limited to the areas where the calcium phosphate fibres rolled. Despite good bone tissue tolerance, intraarticularly, these biomaterials can lead to synovial inflammation. This phlogogenic action varies greatly depending on the microcrystals injected. The factors which might affect the joint inflammatory reaction, including the size and surface of the microcrystals, the crystallinity, pH and physical treatments (heat, compaction) should be further evaluated with precision.

Synthetic calcium phosphates: models for biological crystals?

Characterization of the mineral phases of calcified tissues or ectopic calcifications has demonstrated the complexity of biological calcium phosphate salts. Chemists and numerous biologists involved in calcified tissue research have generally described bone and teeth crystallites as hydroxyapatite rather than biological apatites. All biological calcium phosphates have a non-stoichiometric formula, and numerous and variable substitutions. Moreover, in vivo transformations/maturations occur. There is no particular representative synthetic calcium phosphate crystal either for the normal mineral phases of calcified tissues or for the pathological phases. However, they constitute efficient models for the understanding of biological mineralization, and are good approaches to in vitro studies of biomaterials.

Geranyllinalool (Diterpene Alcohol) : An insecticidal component of pine wood and termites (Isoptera: Rhinotermitidae) in four European ecosystems.

Geranyllinalool is an insecticidal component of pine wood and of the defensive secretion ofReticulitermes species. Lethal doses (LD50) were calculated for termites and various ant species. Termite workers were very resistant (10,000 ppm). Ant resistance varies among species according to their trophic strategy and attack mode. The geranyllinalool acts as a natural insecticide against some ant predators (LD50=6 ppm), which use raid or chemical crypsis to invade termite nests. In contrast, predators laying the venom on the cuticle of their termite prey were very resistant (10,000 ppm). Generally, ants acting as space competitors could detoxify the quantity emitted by one termite soldier (18 ppm).