PPD-induced blastogenesis is auto-regulated by suppressor cells generated in vitro.

Suppressor cell induction can be demonstrated during antigen specific blastogenesis by using the same methods which have shown induction of suppressor cells by Con A. Since suppressor cells are rapidly generated during antigen specific blastogenesis, they must regulate the final level of blastogenesis induced during the seven day in vitro incubation.     

Alterations of beta-adrenoceptor-density and cAMP-synthesis in rat-erythrocytes after stress erythropoiesis.

During the maturation of red blood cells from rats after stress erythropoiesis, adenyl cyclase activity and beta-adrenoceptor density (pmoles/mg protein) decrease at distinctly different rates suggesting a different turnover of these membrane units.     

The detection of superoxide anion from the reaction of oxyhemoglobin and phenylhydrazine using EPR spectroscopy

Summary The low temperature EPR spectrum of a quickly reacted mixture of oxyhemoglobin and phenylhydrazine was studied. With the use of a computer, the spectral contribution of methemoglobin in the region of g=2 was subtracted. The remaining spectrum was that of an axial free radical (g=2.00, g=2.06) having the magnetic parameters of superoxide anion. In the presence of superoxide dismutase, this axial radical was not seen, confirming that superoxide anion is indeed generated by the reaction.The portion of this investigation carried out at the Albert Einstein College of Medicine was supported in part by US Public Health Service Research Grant HL-93399 from the Heart and Lung Institute and by National Institute Contract Nol-CP-55606 to J.P. This is communication No. 378 from the Joan and Lester Avnet Institute of Molecular Biology.Predoctoral fellow in the Medical Scientist Training Program (United States Public Health Service Grant 5-TO-5-GM 01669-12) at the New York University School of Medicine.Recipient of a grant-in-aid from the New York Heart Association.     

The structure of amoorastatone and the cytotoxic limonoid 12-hydroxyamoorastatin

Summary 2 new limonoid-type terpenes have been isolated from an aqueous extract of seeds produced by the Eastern Himalayan (India) plantAphanamixis grandifolia Bl. By interpreting principally mass spectral and nuclear magnetic resonance data, the structures of 12-hydroxyamoorastatin (2b) and amoorastatone (3) were elucidated. Unequivocal evidence for the 12-hydroxyamoorastatin structural assignment was obtained by chemical conversion to sendanin (4). Amoorastatin derivative2b was found to significantly inhibit growth of the murine P388 lymphocytic leukemia cell lines but amoorastatone in the same system was inactive. In a comparative biological study, sendanin (4) and anthothecol (7) were also found significantly to inhibit growth of the P388 cell line, while rohitukin (8) and limonin (9) were found to be inactive.Part 63 of the series Antineoplastic Agents. For the previous contribution refer to G.R. Pettit, T.S. Krupa and R.M. Reynolds, Int. J. Peptide Protein Res., in preparation. The present investigation was supported in part by Public Health Research Grant No. CA-16049-05 from the National Cancer Institute, the Fannie E. Rippel Foundation, Mrs Mary Dell Pritzlaff, the Spencer T. and Ann W. Olin Foundation, Mr John F. Schmidt, and the Phoenix Coca-Cola Bottling Company.     

In vitro inactivation of corpora allata of the bugOncopeltus fasciatus by precocene II

Summary Corpora allata fromOncopeltus fasciatus incubated in vitro in medium containing 10^–5.35 M (1 g/ml) of precocene II lose their ability to secrete juvenile hormone when reimplanted into last instar larvae.Acknowledgments. We thank Mr K. Dorn, Mrs L. Dolezal, Mrs V. Nötzli-Graf, Mr K.H. Trautmann and Mr A. Schuler for technical help, Dr W. Vogel and Dr A. Dübendorfer for valuable discussions.     

Monolayer cultures of perikarya isolated from postnatal rat cerebellum

Summary Viable cerebellar perikarya of mixed cell type obtained from 7–9-day-old rats were maintained in monolayer culture for up to 12 days. During this time extensive neurite formation and outgrowth occurred. The large majority of the cells developing in culture were tentatively identified as granule neurons. This identification was based on the large number isolated from the starting tissue, and the cells general morphological features in culture such as perikaryal and nuclear size, the bipolar nature of neurite extension, and their migratory behaviour.D.N. Currie was supported by a grant from Hoechst Pharmaceuticals, Ld, U.K.J.C. was supported by an S.R.C. Grant to S.P.R. RoseThe authors would like to thank Kathleen Tear for excellent technical assistance and members of the Brain Research Group for helpful discussions.     

0957 + 561 A, B: twin quasistellar objects or gravitational lens?

0957 + 561 A, B are two QSOs of mag 17 with 5.7 arc s separation at redshift 1.405. Their spectra leave little doubt that they are associated. Difficulties arise in describing them as two distinct objects and the possibility that they are two images of the same object formed by a gravitational lens is discussed.