Comportamento delle fosfatasi alcaline all'azione di alcuni veleni carioclasici

Summary The effect of an aqueous solution (6 · 10^–3 M) of mustard oil on phosphatases was tested in cymotoid oocytes by treatment either of fixed and sectioned ovaries or of fresh gonads. Nuclear and cytoplasmic mono- and diphosphatases are destroyed; nucleolar phosphatases on the contrary are unaltered or only slightly damaged.The authors put forward the hypothesis that nucleolar phosphatases have a different kind of enzymatic active groups which might have a low competition factor in regard to mustard oil. Possibly the caryoclasic action of this substance is due, at least in part, to the destruction of alkaline phosphatases which are necessary to mitotic processes.     

Activation concomitante par l'hétéroauxine de la résorption du corps paranucléaire ribonucléique et de la germination des zygotes chezAllomyces

Summary Heteroauxin (optimal concentration 10^–5) activates the germination of the zygotes and the dissolution of their RNA nuclear cap inAllomyces javanicus.Alkaline phosphatase has been located cytochemically in the cytoplasm surrounding the RNA nuclear cap.These new observations lead the author to postulate a relationship between the stimulating action of heteroauxin, activation of the phosphatases and awakening of the RNA-protein synthesis dynamic system during the germination of the zygotes inAllomyces.     

Die Serumphosphatasen der Ratte in verschiedenen Lebensaltern

Summary The serum alkaline and acid phosphatases were examined in male rats between the ages of 20 and 300 days, using the method ofHuggins andTalalay ⁴. The activities of acid and alkaline phosphatases increase significantly to the age of 45 days, followed by a highly significant decrease up to 120th day for alkaline and to 75th day for acid phosphatase. After castration, highly significant increases in the acid, but no changes in the alkaline serum phosphatase were observed.     

Dissociation-constants of metal-ion-complexes with alkaline phosphatase from pig kidney

Summary Using metal-ion buffers it was possible to remove Zn²⁺, Mg²⁺ and Mn²⁺ ions of pig kidney alkaline phosphatase reversibly. The dissociation constants obtained are K_EMg:4·10^–7 M, K_EMn:4·10^–8 M and K_EZn:8·10^–13 M (22°C, pH:9.6, :0.07).Acknowledgement: The authors thank Dr.H. U. Wolf for helpful suggestions and valuable discussion and MissH. Köth for technical assistance.     

The effect of proctolin on the adenylate and guanylate cyclases in theLocusta brain at various developmental stages

Summary Proctolin at concentrations 10^–8–10^–7 M elevated by 40% brain adenylate cyclase activity of adultLocusta migratoria migratorioides R.F. In moulting individuals, proctolin caused a decrease in brain adenylate cyclase activity, and it proved to be ineffective in the larvae. Proctolin caused only a slight decrease on guanylate cyclase activity of the brain at every developmental stage.     

The inhibitory effect of paraquat on histamine and isoproterenol induced changes of cyclic nucleotides in rat lung slices

Summary The incubation of rat lung slices with paraquat ion (10^–4 M) had no effect on cAMP and cGMP levels of the rat lung slices. The preincubation with the same concentration of paraquat inhibited the cAMP elevating effect of histamine (10^–5 M) and isoproterenol (10^–5 M) and reduced the cGMP level to approximately 50% of the level obtained without preincubation with paraquat.This work was supported by the Research Grant No. 5 R01 HL 19720-03 from NHLI Department of Health, Education and Welfare, Washington, D.C.     

Die Wirkung von Theophyllin auf den cellulären Ca-Stoffwechsel des Warmblüterherzens

Summary In isolated, electrically driven, left guineapig atria, theophylline (5×10^–4 g/ml) increased the rate of⁴⁵Ca uptake and release without affecting the total myocardial Ca content and the amount of exchangeable cellular Ca. In sheep and calf heart preparations, theophylline (10^–4–10^–3 g/ml) increased Ca inward current during excitation (as examined indirectly by Ca dependent changes of membrane potential in TTX-containing solutions) as well as tension development. It is concluded that the positive inotropic effect of theophylline in mammalian hearts is due to an increase in Ca influx during the excitation process.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Effects of the adenylate cyclase activator forskolin and its inactive derivative 1,9-dideoxyforskolin on insect cytochrome P-450 dependent steroid hydroxylase activity

The adenylate cyclase activator forskolin and its pharmacologically inactive derivative 1,9-dideoxyforskolin were found to inhibit in a dose-dependent fashion the ecdysone 20-monooxygenase activity associated with wandering stage larvae ofDrosophila melanogaster and fat body and midgut from last instar larvae of the tobacco hornworm,Manduca sexta. The concentrations of these labdane diterpenes required to elicit a 50% inhibition of the cytochrome P-450 dependent steroid hydroxylase activity in the insect tissues ranged from approximately 5×10^–6 to 5×10^–4 M.     

Effects of hydralazine on the elasticity of collagen

Summary The elasticity module of collagen fibres from the tail tendon of the rat was reduced after incubation with hydralazine (10^–4 to 10^–1 mM/ml). It was also diminished by two metabolites of hydralazine.These investigations were supported by the Deutsche Forschungsgemeinschaft, No. 102/9.Acknowledgment. The authors thank R. Jonack and Dr H. Riedl for technical assistance and helpful discussions.     

Fatty acid modulation of antiestrogen action and antiestrogen-binding protein in cultured lymphoid cells

Summary Nonsteroidal antiestrogens reversibly and specifically inhibited the proliferation of two estrogen receptornegative lymphoid cell lines (EL4 and Raji) in a dose-dependent manner. [³H]Thymidine incorporation of concanavalin A-stimulated primary splenocytes was also inhibited by 10^–6 M clomiphene (1-[4-(2-diethylaminoethoxy)phenyl]-1,2-diphenyl-2-chloroethylene). The antiproliferative effect could be prevented by the simultaneous presence in the growth medium of 10^–5 M linoleic acid or 10^–5 M arachidonic acid but not by 10^–6 M estradiol. Both lymphoid cell lines had high affinity antiestrogen-binding sites whose affinity could be altered by conditions of growth. Growth of EL4 cells in RPMI 1640 medium supplemented with charcoal-pretreated 5% fetal calf serum (charcoal-stripped medium) resulted in significantly higher affinity (K_d 0.54 nM±0.11 nM; n=6) than growth in medium supplemented with untreated serum (complete medium) (K_d=1.68 nM±0.48 nM; n=6) (p<0.001). This change in affinity was partly due to removal of fatty acids from the growth medium by charcoal pretreatment, since addition of 10^–5 M linoleic acid or 10^–5 M gamma-linolenic to charcoal-stripped medium decreased the affinity of the antiestrogen-binding protein. In contrast, growth in 10^–5 M stearic acid or 10^–5 M oleic acid did not significantly alter the affinity of the antiestrogen-binding protein, whereas 10^–5 M palmitic acid significantly increased its affinity. The same fatty acids were also tested for their intrinsic effects on EL4 cell proliferation. Oleic, linoleic and gamma-linolenic acids were growth stimulatory while stearic and palmitic acids were not. Thus linoleic and gamma-linolenic acids whose presence in the growth medium was associated with decreased affinity of [³H]tamoxifen (1-[4-(2-dimethylaminoethoxy)phenyl]-1,2-diphenylbut-1(Z)-ene) binding to the intracellular antiestrogen-binding protein were also growth stimulatory. Unsaturated fatty acids have previously been shown to inhibit binding of [³H]tamoxifen to the antiestrogen-binding protein in a cell-free system. The present observations demonstrate that unsaturated fatty acids also modify the affinity of the antiestrogen-binding protein in intact cells.     

The growth-retarding effect of Alden in Spirodela oligorrhiza

Summary Alden® (10^–5 M) retarded growth and increased chlorophyll and protein contents in Spirodela, the effects being reduced by gibberellin and benzyladenine. Alden nearly doubled activity of soluble phosphatase and increased activity of RNase.Acknowledgments. Original inoculum of S. oligorrhiza was kindly supplied by Prof. E. G. Bollard and Dr. A. R. Ferguson of the Plant Diseases Division, D. S. I. R., Auckland, New Zealand. Alden® was kindly supplied by Dr. W. H. De Silva of Dr R. Maag Ltd., Chemical Works, Dielsdorf, Switzerland.     

Interaction of polyamines or their precursors with the calcium-controlled secretion of peroxidase by sugarbeet cells

Summary Three polyamines tested (cadaverine, spermidine and spermine) and their 2 precursors (the amino acids arginine and ornithine) inhibit the Ca²⁺-mediated secretion of peroxidases by sugarbeet cells in suspension culture at concentrations ranging from 10^–15 to 10^–5M. In the absence of exogenous Ca²⁺, spermine added at higher concentrations mimics the activatory effect of Ca²⁺, the other polyamines being without effect.Supported by the Belgian FRFC (grant No. 2.9009.75 to T.G.) and the Swiss National Foundation for Scientific Research (grant No. 3.140-0.81 to C.P. and H.G.).     

Picrotoxin-diazepam interaction in a behavioural schedule of differential reinforcement of low rates

Summary In rats working in a behavioural schedule of differential reinforcement of low rates (6 or 10 sec), picrotoxin (1 mg kg^–1) decreased the number of premature responses and increased (in DRL 10 sec only) the number of rewarded responses. The effect of picrotoxin was antagonized by diazepam (2 mg kg^–1). In contrast to picrotoxin, strychnine (1.5 mg kg^–1) increased the number of premature responses.This work was supported by a grant of I.N.S.E.R.M. (ATP 39-76-71).     

Zur Wirkungsweise einiger Katalase-Inhibitoren

Summary The mechanism of catalase inhibition by CN^–, N ₃ ^– , and SH^– has been investigated by a polarographic method. CN^– has been found to inhibit reversibly by a coordinating mechanism, whereas N ₃ ^– and SH^– inhibits catalase irreversibly.     

Microbial degradation of bitumen

Summary A blown bitumen Mexphalte R 90/40 with a high content of saturated hydrocarbons was degraded by several microorganisms to the same extent. In batch cultures ofSaccharomycopsis lipolytica, maximal biodegradation was estimated to be about 9% w/w, 3.2·10^–3 g/cm² and 3.1·10^–3 cm of degraded bitumen. The Mexphalte R 90/40 degradation rate was closely coupled to biofilm formation. The microbial activity concerned predominantly the oxidation of saturated hydrocarbons. A direct distillation bitumen 80/100 with a low content of saturated hydrocarbons and a high content of aromatic hydrocarbons and resins was more resistant to biodegradation.     

Effects of ouabain and furosemide on saliva secretion induced by sympathomimetic agents in isolated,perfused rat submandibular glands

Summary The presence of 10^–3 M ouabain or furosemide in the perfusate inhibited saliva secretion induced by either isoproterenol (10^–5 M) or phenylephrine (10^–5 M) from isolated rat submandibular glands and caused characteristic alterations in the electrolyte composition of saliva.     

Effect of the calmodulin inhibitor R24571 (calmidazolium) on rat embryos cultured in vitro

Summary The possible effects of inhibition of the calcium-binding protein, calmodulin, on mammalian morphogenesis have been investigated by culturing rat embryos in vitro from 9 1/2 to 11 1/2 days of development in the presence of R24571 (calmidazolium), a specific inhibitor of calmoldulin. Embryos cultured in 10^–2 mM R24571 for 48 h show inhibited development and exhibit a range of morphogenetic abnormalities including assymetry and neural tube defects. Embryos exposed to R24571 for the first 24 h of a 48 h culture are more severely affected than embryos exposed to R24571 for the last 24 h.Acknowledgments. We wish to thank Mr C. Veltkamp and Mr B. lewis for their expert help with the scanning electron microscopy and photography.     

Interaction of diltiazem with propranolol on atrioventricular conduction and refractoriness in the dog

Summary Propranolol pretreatment (0.1 mg·kg^–1) significantly increased the lengthening induced by diltiazem (0.15 mg·kg^–1+0.01 mg·kg^–1·min^–1, 20 min) of the A-H interval of His bundle potential recordings in the dog. In the presence of propranolol, diltiazem also significantly increased the atrioventricular effective refractory period. The results suggest the possible occurrence of AV blocks as a result of the use of a diltiazem-beta blocker combination in clinical practice.Acknowledgments. Financial support from the U.E.R. Biologie Humaine is gratefully acknowledged.     

Effect of enkephalins in the presence of the antibiotic bacitracin in the longitudinal muscle strip preparation from guinea-pig ileum

Summary The antibiotic bacitracin (5×10^–5–4×10^–4 M) increases the inhibition of the contractile response caused by both enkephalin release and direct application of Met-enkephalin 5×10^–7 M in the longitudinal muscle strip preparation from guinea-pig ileum. This effect is attributed to an inhibition of enkephalin degrading peptidases by bacitracin.