Sur l'inhibition sélective des acétylcholinestérasesin vivo chez le chien

Summary 3318 CT [bis(piperidinométhylcoumaranyl-5) cetone diméthiodide] a compound recently synthesized byA. Funke andK. von Däniken, is shown to be a potent and selective inhibitor, bothin vitro andin vivo, of the blood acetyl-cholinesterase (AcChE) of the dog. It produces acetylcholinomimetic symptoms in the animal and sensitizes different responses to acetylcholine and to stimulation of cholinergic nerves without inhibiting the blood non-specific cholinesterase (XChE). However, the action of 3318 CT appears to be limited, both in nature and in intensity, when compared to that of prostigmine, although the latter substance is a less potent inhibitor of AcChEin vitro than is 3318 CT. This difference is probably related to many factors, one of which may be the fact that prostigmine inhibits not only AcChE but also XChE; and it is not yet ascertained that XChE plays no role at all in the limitation of the effect of the stimulations of cholinergic nerves.     

Actions de la néostigmine,du D.F.P. et du 3318 CT sur la sensibilité du rectus de grenouille aux esters acétique,propionique et butyrique de la choline

Summary The potentiating effects of Neostigmine, D.F.P. and 3318 CT (a selective true cholinesterase inhibitor) on acetylcholine (ACh), propionylcholine (PrCh), butyrylcholine (BuCh) and amyltrimethylammonium (AmT), have been studied using the frog's rectus abdominis. Neostigmine increases the actions of the three esters much more than that of AmT. Low concentrations of D.F.P. potentiate maximally BuCh but have practically no effect on ACh, PrCh, and AmT. 3318 CT potentiates AcCh and PrCh but inhibits BuCh and AmT.These results indicate the specificity of the hydrolysis of pharmacologically active doses of BuCh, on the one hand, of AcCh and PrCh, on the other hand, by different enzymes or the frog's rectus.Results obtained with high concentrations of D.F.P. and with association of the different anticholinesterases indicate that a maximal or nearly maximal potentiation of one of these esters is already obtained with the specific inhibitor concerned; the supplementary inhibition of the non-specific enzymes thus appears to have no or only a poor effect.     

Action d'un inhibiteur de la carboanhydrase,l'acétazolamide,sur l'excitabilité du cortex,du thalamus et du rhinencéphale

Summary The electrical activity induced by stimulation of the cortex, diencephalon and rhinencephalon was studied in the rabbit under the influence of a carbonic anhydrase inhibitor, acetazolamide or Diamox. A significant decrease of the excitability was found in the diencephalon.The rapidity and the electivity of this action, as well as the blood pH variations simultaneously registered, suggest a specific inhibition of cerebral carbonic anhydrase by Diamox, although a participation of the metabolic acidosis cannot be fully excluded.     

Recherches sur la pseudo-cholinestérase du sérum et la cholinestérase vraie des globules rouges

Summary By means of a technic published in this journal (2, 66 [1946]), it has been observed that the activity of the pseudo-choline esterase of the serum is highest in presence of high concentrations of acetylcholine.The true choline esterase of the red corpuscules has her optimal activity at concentrations of 200 mg % acetylcholine. This high activity of these choline esterase is only going on during 3 to 5 minutes; after this period an inhibition occurs. At lower substrate concentrations (50 mg % acetylcholine) the difference in activity in the first and second phase is becoming less pronounced and the curve of the choline esterase activity becomes a straight line. At the small substrate concentration (4 mg % acetylcholine) again a primary higher choline esterase activity has been observed.Choline inhibitsin vitro the activity of the choline esterase. Prostigmine inhibits alsoin vivo andin vitro, the choline esterase of serum and globules.     

Recherches sur le mécanisme de la rétraction du caillot et de la métamorphose visqueuse des plaquettes

Summary The concept, that viscous metamorphosis of platelets and clot retraction is initiated by thrombin and a dialyzable factor was confirmed. Under certain circumstances glucose acts as dialyzable factor. Clot retraction seems to depend upon the catabolism of glucose.     

Inhibition sélective des «vraies» et «pseudo»-cholinestérases du rectus de grenouille

Summary The hydrolysis of acetylcholine chloride (0.01M) by frog's rectus extracts, is inhibited by low concentrations of 3318 CT (CI-50 3.2×10^–7) and high concentrations of D.F.P. (CI-50 1.3×10^–5). Inversely, the hydrolysis of butyrylcholine perchlorate is inhibited by low concentrations of D.F.P. (CI-50 3×10^–9) and high concentrations of 3318 CT (CI-50 3×10^–4). Both are inhibited by similar concentrations of neostigmine (CI-50 1.1×10^–7 and 1.5×10^–7). Frog's rectus thus contains true and pseudo-cholinesterases. The inhibitions produced by D.F.P. added to the muscle itself (and not the extract) correlates well with the potentiation of the corresponding ester. Sensitization to AcCh and to BuCh appears to be specifically related to the inhibition of Ac ChE for the former ester, of XChE for the second one.     

Effet du fluoroacétate et des rayons X sur la teneur en acide citrique du foie de la souris

Summary In contrast to rats, male mice injected with sodium fluoroacetate accumulate citrate in their livers, whereas females do not. Whole-body irradiation reduces the level of accumulated citrate in the liver as well as in other tissues of the mouse.     

Influences des modifications simultanées de la concentration en ions K et Ca du liquide céphalorachidien sur le système vasomoteur

Summary In dogs anæsthetized with morphine-chloralosane, the cerebral ventricles are perfused with artificial solutions. After having been warmed up to body temperature, these solutions are allowed to flow into a lateral ventricle by a needle inserted laterally through the skull, the outflow taking place through a second needle placed suboccipitally in the cisterna. An excess of potassium in the cerebral ventricles increases the vasomotor tonus and the vasomotor responses produced by faradization of the central end of the vagus in the neck and by changing the pressure in the isolated carotid sinuses. An excess of calcium depresses the tonus of the vasomotor center and its reflex responses. An excess of calcium may be neutralized by an excess of potassium. Perfusion with a solution containing no calcium increases the tonus and the responses of the vasomotor center, while the absence of potassium does not seem to have any influence on the vasomotor system. A solution without potassium and calcium produces an increase of the tonus and the responses of the vasomotor center, these effects being due to the absence of calcium.     

Sur l'influence de l'aneurine sur la formation des nodosités bactériennes nitrogènes

Summary In certain cases, the production of bacterial nodules on legumes can be influenced by aneurin. The preliminary trials should be continued in order to establish the most favourable conditions of aneurin action.     

Action de l'orientation et de la qualité de la lumière sur le développement des protonémas de Bryales

Summary The radiations coming from Blanc Brillant de Luxe' fluorescent stimulate the growth and ramification of protonema ofCeratodon purpureus (Hedw.) Brid. This stimulation is caused by red light (660 nm). Multidirectional lightening is more favorable than unidirectional exposition.     

Etude de l'hydrolyse et des propriétés toxiques vis-à-vis des mitochondries de maïs Texas,d'un insecticide,le méthomyl ou S-méthyl-N [(méthylcarbamoy)oxyl] thioacétimidate

Summary Methomyl, or S-methyl-N [(methylcarbamoyl)oxy] thioacetimidate, a common insecticide, has been found to be a specific poison of mitochondria of corn with Texas cytoplasm. Its hydrolysis under very mild acidic conditions affords thiomethyl methylthiosulphonate, which strongly inhibits the activity of CmST and N mitochondria of corn.     

Influence de laβ-mercaptoéthylamine sur la réponse de l'intestin grêle du rat à une irradiation rœntgénienne localisée

Summary Intra-peritoneal injections of 15 mg of B-mercaptoethylamine in rats, with an average weight of 200 g, protect the small intestine against a local irradiation of 500 r on the antero-upper portion of the abdomen.This protection is proved mainly, as compared with the control, by a smaller decrease of cells still in mitosis after 12 and 24 hours and of the migrant cells in resting stage, by a greater precocity and higher quantitative value of the post-radiation normal and subnormal mitotic processes, and by variations in the mitotic formula (namely, in protected animals, a relatively high increase in the amount of metaphases).These experiments seem to prove a certain local and immediate action of the radio-protector, whose effects are not solely limited to the preparation of the generating system of the intestine for the later complete repair of the digestive epithelium.

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(Travail du Centre anticancéreux de l'Université de Liège et du Centre national belge pour l'étude de la croissance normale et pathologique).     

Propriétés antiacétylcholinestérasiques du diiodométhylate debis-(diméthylamino-3-phénoxy)-1-3 propane,de ses dérivés phénoliques et des esters carbamiques correspondants

Summary Thein vitro anti-acetylcholinesterase properties ofbis-(dimethylamino-3-phenoxy)-1-3 propane dimethiodide (2842 CT) of two phenolics derivatives (3443 CT and 3116 CT) and of the two corresponding carbamic esters (3152 CT et 3113 CT) have been compared using human red blood corpuscles as enzyme source; under specified conditions, the Cl-50 are respectively 8 × 10^–7 M for 2842 CT, 3.5 × 10^–9 for the two phenolic compounds, and 1.5 × 10^–9 for the carbamic esters. The potencies of these phenols are very close to those of the carbamates, being a bit higher or lower depending on the concentration of the inhibitor and on the time of the readingThe two phenolic compounds, like 2842 CT, react readily with the enzyme contrarily to the carbamic esters which combine slowly. On the other hand the inhibition by the phenolic derivatives is as stable against washing as that by the carbamates. The carbamates, but not the phenols, show the slow displacement phenomenon.Some of these characteristics are compatible with the hypothesis that carbamic compounds could act through liberated phenolic functions but others indicate that carbamic groups have a role of their own.     

Action d'une irradiation générale sur les échanges d'eau entre le sang et la cavité gastrique pendant l'absorption du glucose

Summary A sublethal dose of X-rays, delivered to guinea-pigs 14 days before a glucose absorption test, alters the pattern of water exchange between the blood and the gastric cavity. The normal dilution, which proves to be a main factor in the regulation of the intestinal absorption of sugar, is no longer achieved.     

L'effet de la basse température sur l'incorporation de précurseurs des acides nucléiques et des protéines dans les cellules du méristème radiculaire deVicia faba

Summary The uptake of labelled RNA and protein precursors inVicia faba root meristems into nuclei at 4°C is less depressed than in the cytoplasm. Reversion of the normal pattern of incorporation would seem to indicate an inhibition of the RNA transfer from nucleus to cytoplasm.     

Effets de la réserpine sur le développement d'Oedipoda coerulescens L. (Acridien,Orthoptère)

Summary Inhibitory effects of reserpine on ecdysis and chromatic adaptation inOedipoda appear to be linked with changes observed in both neural and neuro-endocrine regulating systems.