Decontamination of bacterial infection of monolayer cultures with a specific bacteriophage

Summary A few cell lines and primary monolayer cultures were accidentally infected by bacteria. These cultures were successfully decontaminated by means of the specific bacteriophage virus after quick identification of the responsible bacteria. This method presents a practical interest for preservation of valuable cultures. This work is supported by the Institut National de la Sante et de la Recherche Medicale (France) and the Fondation pour la Recherche Medicale (France).     

Action des acides caproïque et caprylique sur les mitoses de segmentation chez Triturus helveticus Razoumowsky

Caproic (hexanoic) and caprylic (octanoic) acids 0,01 M (pH 5) are comparatively studied. After 3 hours they do not destroy spindle fibers, but produce several abnormalities classified and hierarchized as follows: 1) bipolar mitoses with inactive poles and blocked centrospheres, 2) mitoses with two dominant poles including centrospheres and secondary poles without them, 3) special pluripolar mitoses with an equatorially dissociated spindle and more or less efficient poles. Partial inhibition of polar activity results in extended hyperfibrillar diastema, which proliferates in fibrillar hollow spheres and burses, but is unable of inducing furrowing. Mechanisms of these disturbances are discussed. Asynchronism and acceleration of polar activity are determined by the absence of the first cleavage. Chromosomal alterations (thickening, deformations and clumping) are partially reversible, but result in chromosomes breakage and recombinations. Stronger activity and toxicity of caprylic acid may be related to its longer carbonic chain.     

Viability criteria of islets of Langerhans isolated and purified using Ficoll

Rejection of islet allografts is generally explained by immunologic problems, due to both cellular and antibody mechanisms. But another great problem is in the isolation of intact and viable islets of Langerhans: it is necessary to use a good method of pancreas distention, to determine the optimal concentration of collagenase for digestion, to select an effective technique for purifying the islets. This study correlates the morphology of isolated pancreatic islets of rats and dogs with secretion of insulin. The islets are incubated in a perifusion system and are tested during four periods; the glucose concentrations of the perifusion fluid are: 5.5 mM during the initial 70 min. period, 16.5 mM during the second 60 min. period, 5.5 mM during the third 60 min. period and 16.5 during the fourth 50 min. period. This "double glucose stimulation" is a good test of islet viability. The intact, viable isolated islets showed a significant increase of insulin secretion during the two 16.5 mM glucose periods. Damaged islets with some little morphologic alterations after showed a good insulin release during the first glucose stimulation, but a very poor insulin response to glucose during the second stimulation period.     

Biology of micro-vascularized cartilaginous transplantation in the growing dog

Epiphyseal bone transplantations including growth area have been extensively studied experimentally in different animals and applied in children for several decades. Results were unpredictable and the amount of growth obtained with the graft could get 50 per cent of the normal. Development of microsurgical techniques has determined new possibilities of epiphyseal transfer with the respect of the epiphyseal vascularization. Growth plate germinal cell division is directly related to the epiphyseal vascular respect. In a large multifacetted program we could successively determine the vascular patterns of the donor site areas and then utilized different grafts in some experimental situations reproducing the clinical pathology in children, like hip dysplasia or epiphyseal defects after resection for tumor or infection. Results demonstrate that the main problem, in epiphyseal transplantation, is not vascular but mechanical. Further studies have to be done in this direction.     

Arrangement of collagen fibers in the epiphyses and metaphyses of long bones in vertebrates

The arrangement of collagene fibers in bone epiphyses and mataphyses form various species of reptiles and mammals was studied with a polarized light microscope and with a scanning electron microscope. In spite of the variety of shape observed in the long bone extremities of different species, the collagenic fibers arrangement in the bone epiphyses and metaphyses appeared constant. Even in reptiles known to lack a growth plate, the metaphyseal and epiphyseal fiber patterns evoked those observed in mammals. A common fiber pattern may therefore be proposed which allows the coexistence of two apparently incompatible functions: growth, that induces an increased fragility at the epiphyseo-metaphyseal junction as opposed to mechanical support, which has to cope with load and traction forces at the same junctional site.     

Decontamination of bacterial infection of monolayer cultures with a specific bacteriophage

A few cell lines and primary monolayer cultures were accidentally infected by bacteria. These cultures were successfully decontaminated by means of the specific bacteriophage virus after quick identification of the responsible bacteria. This method presents a practical interest for preservation of valuable cultures.