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.     

A rotating bottle culture method with continuous replacement of the gas phase

Summary A rotator culture method is described which provides a continuous flow of oxygenating gas to cultures in rotating bottles. The system maintains constant O₂ and CO₂ levels in the culture medium throughout the incubation period. It also provides a more stable pH than systems with sealed culture bottles.Acknowledgments. We would like to thank Mr B. Secker, Mr C. Hellon and Mr S. J. Ellis, of the Physiological Laboratory workshop, for constructing the rotator apparatus. We also thank the Medical Research Council, London, for financial support for the project.     

Microwave measurements of the absolute values of absorption by water vapour in the atmosphere

MEASUREMENT of the absolute value of absorption by water vapour at microwave frequencies is difficult because the effect is so small. Far in the wings of the absorption lines, in the so-called 'windows' of the spectrum, it is especially difficult to achieve high accuracy in the free atmosphere. But it is in these windows that the behaviour of the absorption is important from both applied and scientific points of view. Satellite communications, remote sensing of the atmosphere, and radioastronomy, are all influenced by this behaviour. Measurements on an Earth-space path are reported here; the results indicate a nonlinear relationship between absorption and water-vapour content.     

Multiplicity of monoamine oxidase in chick brain

Summary The substrate- and inhibitor-related characteristics of monoamine oxidase (MAO) were studied on chick brain mitochondria. It was found that neither 5-hydroxytryptamine nor -phenylethylamine is the specific substrate for type A and type B MAO in chick brain.     

Global inventory of natural and anthropogenic emissions of trace metals to the atmosphere

FEW (if any) recent studies on the atmospheric cycle of trace metals have considered the flux of the metals into the atmosphere on a global scale. Information on worldwide emissions is needed to assess the transboundary movement of pollutant metals and to validate models of the global atmospheric circulation patterns. The worldwide inventories of the natural and anthropogenic sources and emissions of airborne cadmium, copper, lead, nickel and zinc are presented here. The data summarised here are taken from very detailed studies published elsehwere(1-5).     

Standardization of "exchange" techniques to measure estradiol receptors in extracts exposed to biospecific adsorbants]

The measurement of the binding of steroid hormone receptors to biospecific adsorbants requires the development of "exchange" techniques. Two types of techniques based on the principle of differential dissociation were standardized: solid phase exchange with hydroxylapatite and liquid phase exchange with adsorption of the ligand to charcoal dextran. In both cases, binding of oestradiol to its receptor was measured in calf uterine cytosol extracts. Results obtained by both techniques were comparable. The half-times of the oestradiol-receptor complex dissociation determined from exchange kinetics are on the same order as those obtained by direct methods used in previous studies.     

Monoamine oxidase activity of the hypothalamus and pituitary: alterations after pinealectomy, changes in photoperiod, or additions of melatonin in vitro.

Rat pituitary MAO activity was reduced by constant darkness and by additions of melatonin in vitro and was increased by constant light and by pinealectomy. Hypothalamic MAO activity followed the same pattern but was less dramatically affected. The data suggest that MAO may be a target enzyme for melatonin.     

Early investigations on the effect of methyl mercuric chloride upon DMN-acute hepatotoxicity

Summary Acute toxicity induced by DMN was partially prevented by previously administering methyl mercuric chloride (MMC), a chemical inhibitor of the drug metabolizing enzyme system (DMES). We have studied the early changes occurring during the course of DMN-intoxication, namely disaggregation of polysomal profiles and necrosis, evaluated morphologically and by the release of S-GPT.This work was supported by Consiglio Nazionale delle Ricerche, Roma, Italy.