Z. M. Bacq

L'action indirecte du rayonnement X et ultra-violet

Recent literature and the authors experiments favour strongly the general idea that the action of ultraviolet and X-rays on enzymes, cells, and organisms is not entirely adirect one, that chemical substances (peroxides in the case of U.V. rays, oxidizing short lived free radicals in the case of X-rays) resulting mainly from the action of rays on water molecules, are really the responsible agents. The greatest part of the action of U. V. or X-rays isindirect. It is possible, by injection of cyanide, azide, cysteine, glutathione, thiourea, etc. to decrease very significantly the death rate of rats or mice irradiated with X-rays, but only if the substance is injected before irradiation; so far, the biochemical lesion of X-rays irradiation has been found irreversible.

Action du rayonnement X sur la croissance de la plantule d'orge

We have reproduced inHordeum the phenomenon described bySchwartz: absence of proportionality at certain dosages, between the dose of roentgen rays and the biological effect when one irradiates dry seeds and measures the growth of the coleoptile. Cytological analysis shows an enlargement of the epidermic cells of the coleoptiles up to 500.000 r and a decrease of the number of mitosis up to 200.000 r dose at which the mitotic inhibition is nearly complete. The phenomenon described bySchwartz disappears progressively if one waits 3 to 20 days between irradiation and sowing.

Examen histopathologique de souris irradiées après injection de cystéamine

The injection ofβ-mercaptoethylamine to C 57 black mice before irradiation (700 r) effects a partial protection of liver and spleen. It has a strong accelerating action on regeneration in spleen, intestine and probably thymus. The experiments suggest that this action is related to a protection of glucidic metabolism.

Sur la spécificité des principes extraits de la région neuro-glandulaire de l'ascidieCiona intestinalis

Despite controversial evidence, the authors still believe in the presence of specific substances (ocytocic and dilator of frogs melanophores) in the neuroglandular region of the ascidianCiona intestinalis.

A system in the mammalian skin sensitive to X irradiation and insensitive to the oxygen effect

La chute de pression sous linfluence des rayons X dans une poche de solution saline injectée dans la peau du rat (phénomène décrit parBrinkman etLamberts) se produit aussi en labsence doxygène. Laction de certains radioprotecteurs, mise en évidence par cette technique, est donc également indépendante de loxygène.

Causes de la stérilité des souris femelles irradiéesin toto et protégées par la cystinamine

The cystinamine (1591) Labaz which efficiently protects the life of mice irradiated with a lethal dose of 900 r, fatal for unprotected animals, and allows the complete recuperation of the lymphoïd tissues of these animals, is however unable to prevent ovarian atresia. This is probably due to the fact that this amount of 900 r greatly exceeds the sterilizing dose.

Cardiac glucosides and Lundsgaard contracture

De nombreux arguments dordre pharmacologique, en accord avec quelques expériences biochimiques et des observations cliniques, montrent que la contracture cardiaque provoquée par les corps digitaliques peut-être assimilée à la contracture de Lundsgaard du muscle strié. Une hypothèse de travail est proposée, selon laquelle laction des glucosides digitaliques sur le cœur est la conséquence dune inhibition partielle du métabolisme des hydrates de carbone.

Disparition de la 5-hydroxytryptamine dans les granulations des glandes de la peau deDiscoglossus pictus et deRana temporaria après injection de réserpine

30 min after an intraperitoneal injection of reserpine (5 or 10 mg/kg) in the frog (Rana temporaria) and in the toad (Discoglossus pictus), a substance which has the properties of 5-hydroxytryptamine (argentaffine reaction, azoreaction, indoreaction and fluorescence in U.V. after formaldehyde) disappears from the skin glands; the histochemical reactions are more positive again 1 1/2 to 2 h after the injection of reserpine.