Genetic variability in French dog breeds assessed by pedigree data.

Pedigree data of nine French dog breeds, namely Barbet (BAR), Basset fauve de Bretagne (BAF), Beauceron (BEN), Berger des Pyrénées (BRP), Bouledogue Français (BUF), Braque Saint-Germain (BQG), Dogue de Bordeaux (DOB), Epagneul Breton (EPB) and Montagne des Pyrénées (MOP), were analysed. The effective numbers of ancestors of dogs born from 1997 to 2001 were equal to 6.7 (BAR), 40.2 (BAF), 36.5 (BEN), 16.0 (BRP), 37.0 (BUF), 13.1 (BQG), 28.9 (DOB), 33.3 (EPB) and 34.0 (MOP). The expected contributions of the major ancestors were found to be highly unbalanced in the EPB and BRP. The average coefficient of inbreeding of dogs born from 1997 to 2001 with both parents known was equal to 12.4% (BAR), 3.9% (BAF), 5.4% (BEN), 7.2% (BRP), 3.3% (BUF), 6.0% (BQG), 4.1% (DOB), 4.5% (EPB) and 4.0% (MOP). These values were found to be significantly higher than the average coefficient of kinship between the male and the female parents of these animals, except in the BAR and BQG, revealing an usual practice of mating between related animals. The results are discussed in relation with the demographic situation and the use of each breed. The method used to class an endangered breed and the ways to preserve the genetic variability, when necessary, are evoked.

Antibiotic-impregnated plaster of Paris beads. Trials with teicoplanin.

Teicoplanin-impregnated plaster of Paris beads were made and in vitro release properties were studied. Teicoplanin was released in an initial massive dose, with a rapid decline during the first three days, followed by a slowly declining prolonged release up to 30 days. The release tested by diffusion in gelose and high-performance liquid chromatography was found to be 21.4% and 28.2%, respectively, of the amount theoretically present in the beads. Plaster of Paris is a resorbable, nontoxic biomaterial that has already been used to fill dead spaces in bone and deliver antibiotics in the treatment of chronic osteomyelitis. The addition of teicoplanin, a new antistaphylococcal agent with low known bacterial resistance, is a promising alternative. Follow-up tests in vivo, simulating local conditions of the osteomyelitic bone, are necessary to prove efficacy.

[Osteogenesis induced by the addition of demineralized bone matrix to plaster pellets with antibiotics. Animal experiment]. / Ostéogénèse induite par l'addition de matrice osseuse déminéralisée à des billes de plâtre aux antibiotiques. Etude chez l'animal.

The authors have previously shown the role of antibiotic loaded plaster-of-Paris pellets in the treatment of bone loss. In the present paper, a study has been made of the effects of osteogenesis of added decalcified bone matrix in powder. The experiment was made by the implantation of pellets in the muscles of rabbits. It was shown that bone induction by pellets of bone matrix was slightly lower when Rifamycin was added and was not modified by the addition of Fucidin or Gentamycin. The exudation of antibiotics was not diminished by the addition of bone matrix to plaster-of-Paris pellets. The double action, on infection and on bone induction, of composite pellets of plaster-of-Paris with antibiotics and bone matrix may lead to their use in the treatment of septic bone cavities since the pellets are absorbable.

Thymic nurse cells and thymic repopulation after whole body sublethal irradiation in mice.

Thymic Nurse Cells (TNCs) are lymphoepithelial complexes which are thought to play a role in the early stages of the intrathymic differentiation pathway. Therefore, their repopulation kinetics were analyzed in mice after sublethal whole-body irradiation. Changes of the number of TNCs per thymus were parallel with the evolution of the whole thymocyte population. Particularly, a first wave of TNCs restoration was followed by a secondary depletion and a final recovery. This suggests that TNCs restoration is related to the proliferating progeny of intrathymic radioresistant thymocytes. When normal bone marrow cells were grafted intravenously after irradiation, no secondary depletion was found. This pattern of restoration was obviously related to thymic repopulation by cells which were derived from the inoculated bone marrow. Homing studies with FITC labelled bone marrow cells showed that inoculated bone marrow cells did not penetrate TNCs early after irradiation. Later on, when immigrant cells started to proliferate, they were found preferentially within TNCs before spreading in the whole thymus. The results indicate that interactions between immature thymocytes and epithelial cells within TNCs are critical for the first steps of intrathymic lymphopoiesis.

[Plaster of Paris pellets containing antibiotics in the treatment of bone infection. New combinations of plaster with antibiotics]. / Billes de plâtre de Paris aux antibiotiques dans le traitement de l'infection osseuse. Nouvelles associations plâtre-antibiotiques.

The author has tested the action of antibiotic-loaded plaster of Paris loaded pellets in 15 patients with success in 13. Previous studies using plaster of Paris for filling bone defects are noted, plaster being well tolerated and absorbable. Gentamycin, Fucidin and Cefazolin were tested first. In a second series, Netilmicin, Amikacin, Rifamycin and Rifampicin were also used. The preparation of the pellets is fully described. In most instances they can be sterilized by gamma rays except for Fucidin and Cefazolin. Several hundred pellets can be used simultaneously. A study of the elimination of antibiotic in the urine was made. It was concluded that the concentrations obtained by this method in the tissues were highly satisfactory.

Antibiotic loaded plaster of Paris pellets: an in vitro study of a possible method of local antibiotic therapy in bone infection.

Plaster of Paris is an effective ancillary treatment in the surgery of infected cavities in bone. It is well tolerated and spontaneously absorbed over a period of weeks to months, being replaced by bone of normal architecture. It effectively obliterates much of the dead space, leaving little room for hematoma formation. It would appear logical to treat local infection, especially involving rigid walled cavities, by a locally diffused antibiotic. When incorporated into plaster of Paris pellets, two antibiotics, Fucidin and gentamicin, are capable of prolonged local release in bacteriocidal concentrations. On the basis of in vitro observations on bacterial cultures, it is proposed that antibiotic-plaster of Paris pellets might be a simple adjuvant technique to good surgical debridement in the treatment of bone infection. Plaster of Paris has the practical advantage over acrylic cement beads containing antibiotics in that it is resorbed and would not need a subsequent operation to be moved.

[Migration of bone marrow cells to the thymus in mice after a single sublethal-dose irradiation]. / Migration des cellules de moelle hématopoïétique vers le thymus chez la souris après une irradiation unique à dose sublétale.

In sublethally irradiated mice, thymus repopulation is due first to the proliferation of surviving thymocytes followed by the multiplication of bone marrow derived prothymocytes. The migration of bone marrow cells to the thymus after a single sublethal whole-body X irradiation was studied by using fluorescein isothiocyanate as a cell marker. Irradiation increases the permissiveness of the thymus to the immigration of bone marrow cells. Furthermore, the post-Rx regenerating bone marrow cells exhibit migration capacities greater than the normal ones. The radiation induced changes in the bone marrow thymus interaction might play an important role in thymus regeneration after sublethal irradiation.

Thymic nurse cells are the first site of virus replication after inoculation of the radiation leukemia virus.

The induction of thymic lymphomas by inoculation of the Radiation Leukemia Virus (RadLV) requires interactions between RadLV, lymphoid cells and thymus microenvironment. The possible localization of this interaction within the peculiar lymphoepithelial complexes called 'thymic nurse cells' (TNCs) has been investigated. Electron microscopic studies, as well as in vitro experiments using a very sensitive infectious centre detection assay demonstrated that most of the first virus producing cells after RadLV inoculation are located within the TNCs. Most of these structures belong to the thymus subcapsular zone. They contain lymphoid cells with the phenotype of the major (cortical) thymocyte population. Data support the view that a limited subpopulation of subcapsular immature thymocyte can act as specific targets for productive infection with RadLV. Furthermore, the initiation of virus replication appears related to the interaction between the immature thymocyte and the 'nurse cells' microenvironment.