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plasma-ammonia concentration. Infections and con-

sequent catabolism may cause hyperammonaemia,and they should be treated rigorously. Most workershave found no great benefit from anabolic steroidsor intestinal sterilisation by the administration ofpoorly absorbed broad-spectrum antibiotics It hasbeen claimed that the administration of citric acidtended to lower blood-ammonia levels and to produceclinical improvement.9 It is hard to understand whysuch small doses as 3 g. daily should be effective, butpresumably the benefit is partly the result of acidi-fication of the urine and increase in ammonia elimina-tion. If, despite these measures, the plasma-ammonialevel becomes very high and the patient lapses intocoma, intravenous therapy is needed, and proteinintake should be stopped completely. HERRIN andMCCREDIE 10 found peritoneal dialysis useful in thereduction of very high ammonia levels in one patient.They were successful in reducing the blood-ammoniafrom 1625 to 270 g. NH3-N per 100 ml. over aperiod of thirty-six hours, but the patient did notsurvive. As with other inborn errors of metabolism,the prognosis depends on the degree of metabolicimpairment; and early suspicion, prompt diagnosis,and immediate treatment are vital.

Annotations

LIFE ON THE MOON

WHATEVER misgivings the world may feel as it con-templates the paradox of men walking on the moon andchildren starving in Biafra, the magnificence, intechnology and in valour, of the United States’achievement will stand high in the record ofman’s conquests. No one can tell where the trail inspace will lead or whether it will ever yield great profitwith which to advance the fight against suffering onearth. But the moon landing was the hour when thegloomiest doubters admitted that a remarkable feathad been accomplished, when the children stayed up,unreproached, late into the night to cheer the Ameri-cans to their goal, and when the enthusiasts spoke of anew era.

Whether or not the moon is entirely lifeless is still

anyone’s guess. It was never very likely that whenArmstrong and Aldrin stepped from the lunar modulelast Monday they would be met by a little green manor an intelligent protozoon the size of a goat. The lunarclimate is harsh and has a huge diurnal range of tem-perature ; and if life of any sort has developed there,a reasonable guess is to expect, among other things,something comparable to our terrestrial bacteria.Some of these will survive extremes of heat, cold, anddesiccation fatal to the higher plants and animals.Long experience has demonstrated the awful conse-quences which may follow the introduction of aparasite of any kind into a virgin and non-immunepopulation, and much trouble and expense has beendevoted to ensuring that the astronauts do not import10. Herrin, J. T., McCredie, D. A. Archs Dis. Childh. 1969, 44, 149.

some streptococci or rhinoviruses to the moon or bringback-who knows what ?

For some weeks before their journey the three

explorers were kept in relative isolation to prevent anynew addition to their indigenous flora. This flora wasmeanwhile recorded in detail, so that any lunarcolonists may be detected later. When they returnthey will leave behind them their tools, boots, cameras,and excreta, all neatly wrapped in plastic bags. Theythemselves will be held in strict isolation under medical

supervision for two weeks while their space-suits andcollection of geological (perhaps biological) specimenswill be examined with every sterile precaution in sterilechambers. One risk is that the methods devised for thedetection of terrestrial microorganisms may be quiteuseless when used on material from the moon, but theinvestigators must do the best they can. When theloot has been examined it will presumably be sterilised;and it is to be hoped that lunar parasites (if any) arenot more resistant to heat or chemicals than our nativeones. The disinfection of the vehicle is going to bequite a problem.Some of the earth’s flora may be left on the moon.

The astronauts have been kept free of overt infectiousdisease, and their gear will be sterile or as near sterileas can be. Their space-suits should retain their indi-genous flora rather better than the surgeon’s gown andmask, but at some time they must empty bowels andbladders. It is almost inconceivable that they will notshed some fraction of their normal flora and it is smallcomfort if these are labelled " non-pathogenic ". Thedistinction between pathogens and other organismsis no more than statistical and there are few ofthe bacteria commonly isolated by medical micro-biologists which have not, at one time or another,caused human disease. To forecast the behaviour ofany of them on the moon is rash, though it is im-

probable that any member of the human flora willsurvive for long in that environment. But one small

plot on the moon’s surface will never be the same again.

CONTINUOUS CHLORMADINONE ACETATE:IS IT AN EFFECTIVE ORAL CONTRACEPTIVE?

THE virtually 100% efficacy of combined oestrogen-progestogen oral contraceptives has set a high standardagainst which all newer methods have to be judged.Clearly they cannot improve on this performance; soclaims to superiority can be based only on freedomfrom the adverse effects which combined oral contra-ceptives produce in a minority of women, or on theirsuitability for women for whom these older formula-tions are specifically contraindicated, or on wider

acceptability. Because the oestrogen component is

generally held to be responsible for most of the un-toward actions of combined oral contraceptives, theannouncement that continuous chlormadinone acetate-free from oestrogen-in a dose of only 0-5 mg. dailyprovided an effective contraceptive regimen 1 arousedmuch interest. The new method had the simplicity ofrequiring only one tablet daily (there is no stoppingand starting courses of pills, as with older oral contra-1. Rudel, H. W., Martinez-Manautou, J., Maqueo-Topete, M.

Pert. Steril. 1965, 16, 158.