Hemolymph volume determination in the tomato fruitworm,Heliothis zea

Summary The hemolymph volume ofHeliothis zea larvae was determined by the amaranth dye method and found to vary from 28 to 288 l. It averaged 30.6% of b.wt, a value comparable to that obtained with C¹⁴ inulin. Amaranth became evenly distributed in the hemocoele in 3–5 min.     

Down's syndrome: changes in protein fractions of blood plasma

Summary A statistically significant decrease of prealbumin and statistically significant increases of alpha₂-macroglobulin and IgA were found in blood plasma of patients with Down's syndrome using quantitative crossed immunoelectrophoresis.We are indebted to Prof. T.C. Bøg-Hansen, University of Copenhagen, for the helpful discussion of our results.     

Examination of naturally occurring polyacetylenes and α-terthienyl for their ability to induce cytogenetic damage

Summary -Terthienyl and 5 polyacetylenes were examined for chromosome damaging activity using Syrian hamster cells. None of these naturally occurring compounds induced sister chromatid exchanges and neither -terthienyl nor phenylheptatriyne induced chromosome aberrations.The authors wish to thank the National Science and Engineering Research Council for financial support of this research.     

A postsynaptic α, 2-receptor: The alpha-adrenergic receptor of hamster white fat cells

Summary The effects of selected -agonists and -antagonists on theophylline-induced lipolysis were investigate in isolated hamster white fat cells ₂-Agonists (tramazoline, clonidine) inhibited theophylline-induced lipolysis while an ₂-agonist (methoxamine) was without any effect. The inhibitory effect of ₂-agonists was suppressed by yohimbine (₂-antagonist), whereas ₂-antagonists were inefficient. This result implies that the -adrenergic receptor of hamster fat cells is of the ₂-type, although located postsynaptically.Acknowledgments. This work was supported by grants from CNRS (ERA 412) and DGRST (grant No. 787 1078). We thank M. Dauzats for excellent technical assistance. We thank Prof. H. Schmitt for tramazoline and AR-C 239 and for helpful discussion.     

Opposite effects ofβ-adrenoceptor stimulation and 8-bromo-cyclic AMP on potassium efflux in mammalian heart muscle

Summary -adrenoceptor stimulation by isoprenaline increases the potassium efflux in beating guinea-pig atria. This effect is not mimicked by 8-bromo-cyclic AMP, a cyclic AMP analogue which exerts a positive inotropic effect in this preparation.     

The effect ofβ-adrenergic stimulation and blockade on the efflux of PGE1-like material from the isolated perfused rabbit heart

Summary Prostaglandin (PG) release was measured from the isolated perfused rabbit heart. The effects of -adrenergic stimulation and blockade suggest that PG synthesis is regulated in part by adrenergic mechanisms.     

Age-related differences in the urinary excretion of prostaglandin F2α catabolites in the rat

Summary Tritium-labelled PGF₂ was administered i.v. into rats of varying ages (2, 4, 6 weeks and adult). Urine was collected and assayed for radioactive products by thin-layer-chromatography. Results showed a distinctly different urinary profile between the 2-week-old and the adult rat. While the urinary pattern from the 2-week-old rat gave a single less polar product than PGF₂, the pattern from the adult rat gave products more polar than PGF₂. Urine from the 4- and 6-week-old rats gave a mixture of these types of products. These results indicate that some prostaglandin catabolic pathway (likely the -oxidative system) is activated in vivo within the 4–6-week postnatal period in the rat.Supported by a grant (MT-4181) to C.P.-A. from the Medical Research Council of Canada.This study is in partial fulfillment of the requirements for a Ph.D. degree in the Department of Pharmacology, University of Toronto.     

Comparison of white pock (h) mutants of monkeypox virus with parental monkeypox and with variola-like viruses isolated from animals

Monkeypox mutants arising spontaneously or after serial, high multiplicity passage were characterized phenotypically and by restriction endonuclease mapping. Some resemble "whitepox" and variola viruses in several of the markers tested but all are distinguishable phenotypically from these. None resembles "whitepox" viruses in genome structure although near-terminal deletions or symmetrical, terminal rearrangements, relative to parental monkeypox, occurred. "Whitepox" viruses isolated from animals closely resemble variola in both phenotype and genome structure.     

An investigation of the interaction between isoniazid and the contraceptive steroid norethindrone in vivo

Summary Isonicotinic acid hydrazide (isoniazid) was shown to react readily with 17-ethinyl-17-hydroxyestr-4-en-3-one (norethindrone) to form the isonicotinyl hydrazone of the steroid under conditions likely to exist in the stomach. The hydrazone was detected in guinea-pig, but not rat, plasma following its oral administration. Rat liver tissue metabolized the compound more rapidly than guinea-pig liver in vitro which probably accounts for the failure to detect the hydrazone in rat plasma.     

Effect of spike disease on the 5′-and 3′-nucleotidase activities in sandal plants

Summary In the sandal plant affected by spike disease, caused by mycoplasma-like organisms, the changes occurring in the 5-and 3-nucleotidase activities were studied and their possible significance discussed.