Toxicity of some insecticides for crowded and isolated nymphs ofGryllodes sigillatus Wlk. (Orthoptera: Gryllidae)

Summary 6 insecticides; chlordane, malathion, fenitrothion, pyrethrum, rotenone and sevin, were screened againstGryllodes sigillatus Wlk. reared under crowded and isolated conditions. Chlordane was found to be most toxic, followed by malation, fenitrothion, pyrethrum, rotenone and sevin. Insects reared under crowded conditions were more susceptible to insecticides than insects reared under isolated conditions.Acknowledgments. The authors are grateful to Dr S. C. Saxena for providing all facilities.     

A simple procedure for removal of intra- and extra-tumoral macrophages from primary tumor cultures

Summary Improved growth of tumor cells in primary cell suspensions isolated from solid tumors can be achieved by addition of an antifungal agent, mycostatin, to the culture medium. Mycostatin inhibits the cytotoxicity of macrophages and also quickly detaches phagocytes without any apparent retardation of the growth of tumor cells. This method is particularly useful for obtaining cultures of lung tumor cells or cells from lung metastases of other tumors.This research was supported in part by grants CA-22839 and CA-28482 awarded by the National Cancer Institute, DHEW, USA. This is publication No. 406 from the Department of Basic and Clinical Immunology and Microbiology, Medical University of South Carolina.We thank Charles L. Smith for editorial assistance. Address correspondence to Y. Y., Department of Basic and Clinical Immunology and Microbiology, Medical University of South Carolina, 171 Ashley Avenue, Charleston, SC 29403, USA.     

Immunopetentiators and the protection they give against carbon tetrachloride hepatotoxicity

Summary Immunopotentiators such as BCG, levamisole, PS-K and OK-432 prevent carbon tetrachloride (CCl₄) hepatotoxicity, and in spite of exposure to CCl₄ the liver tissue levels of thiobarbituric acid (TBA) reactive substances were not increased in rats pretreated with such immunopotentiators.     

The phorbol ester TPA induces metamorphosis in Red Sea coral planulae (Cnidaria: Anthozoa)

Controlled experiments on the metamorphosis of marine invertebrate larvae require artificial inducers. These inducers can be used for studying the involvement of known signal transduction pathways in settlement and metamorphosis. The ability of the tumor-promoting phorbol ester TPA (12-O-tetradecanoylphorbol-13-acetate) to induce metamorphosis in planulae of the Red Sea soft coral speciesHeteroxenia fuscescens, Xenia umbellata, Dendronephthya hemprichii, Litophyton arboreum andParerythropodium fulvum fulvum, and the stony coralStylophora pistillata, was examined by using various concentrations of TPA. The chemical induced metamorphosis in all six species. The effect was unspecific and concentration-related. For all the corals except forX. umbellata the highest mean percentages of metamorphosis were obtained with 8.1×10^–7–10^–9 M TPA. ForX. umbellata, the percentage of metamorphosis was lower, and was obtained within a wider TPA concentration range. The present results, along with previous studies on Hydrozoa and Scyphozoa, demonstrate that TPA is the first common artificial inducer for these classes of Cnidaria. TPA is known to activate the enzyme protein kinase C (PKC) and therefore plays an important role in studying the phosphatidylinositol signal transduction system. Evidence for the involvement of this pathway in triggering metamorphosis has already been reported for Hydrozoa and Scyphozoa. Our results suggest that PKC is also involved in initiating metamorphosis in Anthozoa.     

Central nicotinic receptor blockade inhibits emotionally conditioned pressor responses in rats

A conditioned stimulus previously paired with electric footshock produced an increase in blood pressure in conscious, freely moving rats. The conditioned pressor response was reproducible. Intracerebroventricular injection of the nicotinic receptor antagonists hexamethonium (1–10 g) or pentolinium (10 g) but not the muscarinic receptor antagonist methylatropine (3 g) produced an inhibition of the conditioned pressor response, whereas intraarterial injection of hexamethonium (10 g) did not affect the response. Intraventricular injection of the cholinesterase inhibitor physostigmine (3–10 g) produced an enhancement of the conditioned pressor response. These results are consistent with the possibility that central nicotinic receptors play a role in the expression of the emotionally conditioned pressor response in rats.     

Further studies on polyacrylamide gel electrophoresis of water-soluble proteolipid-protein from bovine brain white matter

Zusammenfassung Wasserlösliche, proteolipide Proteine wurden von der weissen Hirnsubstanz durch Isolierungsmethoden vonTenenbaum undFolch ² gewonnen. Ohne Lyophilisation ergab die Disk-Elektrophorese bei pH 8.3 zwei Banden.

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The authors express their appreciation to Dr.K. Ueki, Dr.Y. Takahashi, Dr.Y. Takemoto and Dr.T. Kotoku.     

A new one-step synthesis of hexahydrocannabinoid analogs

Summary A one-step synthesis of hexahydrocannabinoid analogs (HHC) is described making use of the condensation of phenolic ketones and aldehydes with citronellal in the presence of pyridine.Grateful thanks are accorded to Drs L. Chopard and S. Selvavinayakam for spectral measurements and Dr I. Fleming for useful discussion.R. Mechoulam and Y. Gaoni, Recent advances in the chemistry of Hashish, in: Progress in the Chemistry of Organic natural products, vol. 25, p. 175. Ed. L. Zechmeister. Springer Verlag, Wien 1967; R. Mechoulam, Marijuana Chemistry and Pharmacology, metabolism and clinical effects. Academic Press, New York 1973; R. Mechoulam, N. K. McCallum and S. Burstein, Chem. Rev.76, 75 (1976).