Struktur-Wirkungsbeziehungen beim menschlichen Calcitonin. III. Die biologische Aktivität verkürzter oder an den Kettenenden modifizierter,synthetischer analoger

Summary Assays of 8 synthetic analogues of human calcitonin in rats showed that their hypocalcaemic activity was drastically reduced by deletion of the C-terminal amide group, chain-shortening or opening of the disulphide ring, but unaffected or enhanced by modification of the N-terminal amino group.

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II. vgl.R. Maier, B. Kamber, B. Riniker andW. Rittel, Hormon. Metab. Res.7, 511 (1975).

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Die hier verwendete, abgekürzte Schreibweise für Peptide folgt den Empfehlungen der IUPAC-IUB Kommission für Biochemische Nomenklatur, J.B.C.247, 977 (1972). Weitere Abkürzungen: HCT, Human-Calcitonin; PCT, Schweinecalcitonin; Bmp, -Mercaptopropionsäure (Desaminocystein); NMet, Normethionin (S-Methylcystein); -OMe, Methylester.     

Differential effects of ethanol on prostaglandin responses of arterial and venous smooth muscle

Summary The present results, using isolated rat aortic strips and portal vein segments, demonstrate that ethanol, depending upon concentration, can either enhance or attenuate the contractile actions of PGF₂ on at least 2 different types of vascular smooth muscle. At the very least, the present findings question the use of ethanol as a solvent when investigating the contractile actions of PG molecules on smooth muscles.Supported by NIH grant No. HL-18015 and NIMH grant No. MH-26236. The authors are indebted to Dr.John E. Pike and Dr.John Babcock of the Upjohn Company for generously providing us with the PGF₂ used in this study.     

The effect of D-6-methyl-8-[β-isopropylaminoethyl] ergoline-I on the lactation in nursing rats

D-6-Methyl-8-[-isopropylaminoethyl] ergoline-I [VÚFB-10726], beginning from the dose of 0.05 mg/kg p.o., suppresses lactation through the inhibition of prolactin secretion in nursing rats.     

Ecdysone 20-hydroxylase from the midgut of the tobacco hornworm (Manduca sexta L.)

Summary An ecdysone 20-hydroxylase enzyme system that converts -ecdysone to 20-hydroxyecdysone was prepared from the midgut of the tobacco hornworm prepupa. This partially purified enzyme is NADPH dependent and is localized in the mitochondrial fraction of the midgut tissue.     

Effect of air ionization on blood serotonin in vitro

Summary The effect of negative and positive air ionisation on siliconized blood serotonin was studied in vitro. The experiments showed that within 10 min positive ionisation increased serotonin levels in total blood (+40%), plasma (+90%), erythrocytes (+50%) and thrombocytes (+200%). On the other hand, negative ionization (10 min) lowered the serotonin content of total blood (–30%), plasma (–42.5%), erythrocytes (–41.7%) and thrombocytes (–72.3%), thus confirming the Krueger Effect in vitro.This research was generously supported by a grant from the Joint Research Fund of the Hebrew University and Hadassah, and Dr. and Mrs.Leonard Appleby of Palmbeach, Florida.Acknowledgment: Our thanks are due to Mr.B. Shalita, Mrs.Zippora Adar and Mrs.Olga Fradkin for devoted technical assistance.     

Effect of 723-1723-1723-1on ethanol withdrawal in mice

Summary ⁹ (10 mg/kg, i.p.) administered to mice immediately after withdrawal from a 3-day exposure to ethanol vapor was found to intensify withdrawal reactions. No effect was seen when ⁹ was administered chronically during the exposure to ethanol.     

RNA synthesis in α-amanitin-poisoned rats: Prevention of recovery by inhibition of protein synthesis

Summary The treatment with cycloheximide of rats previously poisoned with -amanitin hinders the recovery of RNA synthesis observed in the liver of rats treated with -amanitin alone. The recovery of RNA synthesis can be ascribed to the capability of poisoned rats to synthesize new RNA-polymerase II.Acknowledgments: We thank ProfessorT. Wieland for the generous gift of -amanitin. This work was supported by grants from C.N.R., Rome, and by Pallotti's legacy for Cancer Research.     

Effect of hydrogen peroxide on the binding of Merocyanine 540 to human erythrocytes

The fluorescent dye Merocyanine 540 (MC540) is often used as a probe to monitor the molecular packing of phospholipids in the outer leaflet of biomembranes. In a previous study we showed that the increased staining of erythrocytes with a perturbed membrane structure was mainly due to an increase in the fluorescence yield of cell-bound MC540, rather than to an increase of the number of bound molecules. Erythrocytes and ghosts exposed to continuous fluxes of H₂O₂ exhibited pronounced lipid peroxidation. Further, red blood cells subjected to this form of oxidative stress also showed increased staining with MC540. It appeared that this was caused by a strong increase in binding of MC540, together with a slight red shift of the fluorescence emission maximum and a small increase in the fluorescence yield of bound MC540. The changed MC540 binding characteristics were not observed when lipid peroxidation was suppressed by the presence of the antioxidant BHT in the incubation medium. However, open ghosts exposed to H₂O₂ showed no increase of MC540 binding, excluding a direct involvement of lipid peroxidation. Measurement of fluorescence emission spectra and gel filtration studies showed that MC540 can bind to H₂O₂-exposed hemoglobin. Experiments with erythrocytes lysed in hypotonic medium after exposure to H₂O₂ revealed that peroxidation of lipids with H₂O₂ induced a non-specific permeabilization of the plasma membrane to MC540, thereby allowing MC540 to bind to the oxidatively denatured, more hydrophobic hemoglobin. These results indicate that conclusions about packing of phospholipids in the outer leaflet of the membrane based on increased MC540-staining should be drawn with care. Received 27 September 1996; received after revision 5 November 1996; accepted 27 November 1996