Prion Strain Discrimination Based on Rapid In Vivo Amplification and Analysis by the Cell Panel Assay

Prion strain identification has been hitherto achieved using time-consuming incubation time determinations in one or more mouse lines and elaborate neuropathological assessment. In the present work, we make a detailed study of the properties of PrP-overproducing Tga20 mice. We show that in these mice the four prion strains examined are rapidly and faithfully amplified and can subsequently be discriminated by a cell-based procedure, the Cell Panel Assay.     

Effect of hyperthermia on the radioprotective action of cysteamine and isoproterenol

Heating of mouse bone marrow cells up to 42 degrees C was shown to increase their radiosensitivity (DMF = 0.80 +/- 0.12). At this temperature, the radioprotective efficiency of cysteamine was lost completely (DMF = 0.78 +/- 0.09), and radioprotective activity of d,l-isoproterenol significantly decreased (DMF declined from 2.41 +/- 0.23 to 1.67 +/- 0.16). It is assumed that the radioprotective effect of cysteamine on mammalian cells is associated with the processes of the postirradiation DNA repair for just these processes are inhibited by heating. The mechanism of action of a beta-agonist of isoproterenol is perhaps only partially associated with DNA repair.     

The effect of nonspecific immune stimulation with Corynebacterium parvum and polidin on the Ehrlich ascites tumor growth

Investigations were performed: a) to compare the effect of two nonspecific immunostimulants, Polidin and Corynebacterium parvum, on the development of Ehrlich ascites carcinoma in mice; b) to determine whether the effects are dependent on the tumor cell dose inoculated into the animals. C. parvum and Polidin administered prior to Ehrlich ascites tumor inoculation have a protective effect evidenced by a delay in tumor development, a retardation in tumor growth and a prolonged survival of the tumor host. The effect of immunostimulants was highly dependent on the tumor cell dose inoculated into mice and was more marked with C. parvum.     

Chemical protection of golden hamsters against ionizing radiation

It was shown on Golden hamsters, which are characterized by high radioresistance of the intestine, that S-2-(omega-aminopropylaminoethyl) thiophosphorous acid (gammaphos) exerts a protective action against both X- and neutron-radiation although in the latter case the protection is less pronounced. In conditions of hibernation, the protective effect of gammaphos against X-radiation was not statistically reliable. Hibernation during exposure and at the postirradiation period increases considerably the radioresistance of animals. The influence of hibernation depends upon its duration.     

Differential influence of Pomphorhynchus laevis (Acanthocephala) on the behaviour of native and invader gammarid species

Although various species of acanthocephalan parasites can increase the vulnerability of their amphipod intermediate hosts to predation, particularly by altering their photophobic behaviour, their influence on the structure of amphipod communities and the success of invader species has so far received little attention. We compared the prevalence and behavioural influence of a fish acanthocephalan parasite, Pomphorhynchus laevis, in two species of amphipods, Gammarus pulex and Gammarus roeseli in sympatry in the river Ouche (Burgundy, eastern France). There, G. pulex is a resident species, whereas G. roeseli is a recent coloniser. Both uninfected G. pulex and G. roeseli were strongly photophobic, although less so in the invading species. However, there was no significant difference in reaction to light between infected and uninfected G. roeseli, whereas infected G. pulex were strongly photophilic. We discuss our results in relation to the parasite's ability to manipulate invading host species, the possibility that resistant individuals have been selected during the invasion process, and the role that acanthocephalan parasites can play in shaping the structure of amphipod communities.     

Inherent behavioral activity of rats administered different fractions of brain-specific S-100 proteins

The intraventricular injection of brain specific S-100 proteins leads to the prolonged heterochronous changes of the inherent rat behaviour forms during the period of water and food needs restitution. The effects of various doses of S-100 proteins fractions on the behavioural activity differs in the degree of expression and in time of their onset. The specific influence of some S-100 proteins fractions on duration of the different inherent forms of rat behaviour can be explained by plurality of molecular mechanisms of their effects.     

Placebo-controlled study of effects of epimestrol on the pituitary-testicular axis in normal men

Twenty healthy male volunteers were randomly allocated to the treatment with either 15 mg/day of epimestrol or placebo for 10 days. The plasma levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), oestradiol (E2) and prolactin (PRL) were measured before, during and 4 days after the medication by radioimmunoassays. Data were statistically evaluated by means of an analysis of covariance. Circulating LH and FSH, and also T and E2 significantly increased in the epimestrol treated subjects. In the placebo treated subjects no significant changes in the plasma hormone levels were observed. There were no significant changes in the plasma levels of PRL in either group.     

Spruce versus Arabidopsis: different strategies of photosynthetic acclimation to light intensity change

Photosynthesis Research - The acclimation of higher plants to different light intensities is associated with a reorganization of the photosynthetic apparatus. These modifications, namely, changes...