SWALLOWED COINS

1051

Although we are unable to study age-matched controls for ethical reasons, we have found no evidence of an age-related change in total propionate production in additional patients studied (n = 15). The use

of adult controls in the

study does not, therefore, in

any way

International Physicians for the Prevention of Nuclear War

compromise our conclusions. In the fed state aminoacid oxidation is approximately doubled,l the rate of propionate production from aminoacids should be increased similarly. However, even with a two-fold rise in propionate production from aminoacid catabolism a significant proportion of total propionate production would still remain unaccounted for. We chose to study patients when fasted since, in our experience, this is when they are most unstable. During this period the discrepancy between total propionate production and that derived from protein catabolism is unlikely to be due to propionate production from gut flora alone. Odd-chain fatty acids are known to accumulate in MMA,2 and instability during fasting may be due to an increase in propionate production arising from the oxidation of these fatty acids. Recent reviews describing the concepts involved in stable isotope tracer studies are available both in relation to inborn errors of metabolism’ and more generally.4 In our experience, where the intracellular pool has access to the extracellular pool, enrichment and concentration plateaux will be achieved only if these pools equilibrate. Plateaux were achieved in all the studies documented in our paper; we have also shown, in further studies on patients with MMA, the appearance of label in intracellularly derived metabolites, which confirms that the intracellular pool is miscible with plasma. The quantitative aspects of our techniques are further validated by the close agreement between in-vivo rates of propionate production (measured with stable isotopes) and disposal (oxidation + urinary excretion) in MMA subjects.’ Stable isotope techniques have been used to show that patients with a range of inborn errors of metabolism have incomplete metabolic blocks in vivo, despite virtually absent in-vitro enzyme activity.6 Patients with MMA probably oxidise some propionate through alternative pathways and/or through residual enzyme activity in tissues different to those assayed in vitro. so

Department of Child Health, Institute of Child Health, Bristol BS2 8BJ; Murdoch Institute,

Melbourne, Australia; Department of Child Health,

J. H. WALTER G. N. THOMPSON

Institute of Child Health, London; and Nutrition Research

J. V. LEONARD

Group,

D. HALLIDAY

Clinical Research Centre, Harrow

1. Rennie MJ, Edwards RHT, Halliday D, Matthews DE, Wolman SL, Millward DJ. Muscle protein synthesis measured by stable isotope techniques: the effects of feeding and fasting. Clin Sci 1982; 63: 519-23. 2 Wendel U, Diekmann E, Laryea MD. Odd-numbered long-chain fatty acid content in erythrocyte membrane phospholipids in patients with an impaired propionate utilization. J Inher Metab Dis 1988; 11: 225-28. 3. Thompson GN. In vivo substrate metabolism in inborn errors of amino acid and organic metabolism. PhD thesis, University of London, 1989. 4. Thompson GN, Pacy PJ, Ford GC, Halliday D. Practical considerations in the use of stable isotope labelled compounds as tracers in clinical studies. Biomed Environ Mass Spectrom 1989; 18: 321-27. 5. Thompson GN, Walter JH, Bresson JL, et al. Substrate disposal in metabolic disease: a comparison between the rates of in vivo propionate oxidation and urinary metabolic excretion in children with methylmalonic acidaemia. J Pediatr (in press). 6. Thompson GN, Walter JH, Leonard JV, Halliday D. In vivo enzyme activity in inborn errors of metabolism. Metabolism (in press).

SWALLOWED COINS

SiR,—Coin swallowing (the subject of your Sept 16 editorial, 659) used to be common in children attending the casualty department at the main city hospital in Kampala, Uganda. The coins were low denomination "copper" ones and often got stuck in the oesophagus. They were usually removed at oesophagoscopy within a few hours of the diagnosis. With the hyperinflation of the mid-1970s coins lost their value and quickly disappeared from circulation. For a decade, until coins were reintroduced, lodging of coins in the oesophagus of children was rare. This must be one of the p

few beneficial medical effects of inflation. 38 Park Avenue,

Orpington, Kent BR6 9EH

J. WILSON CARSWELL

NO MORE HIROSHIMAS

FIRST, they laid flowers at the cenotaph in Hiroshima, in memory of more than 200 000 people killed by the first act of

nuclear war. Immediately afterwards, Bernard Lown and Mikhail Kuzin, the American and Soviet co-Presidents of International Physicians for the Prevention of Nuclear War (IPPNW), planted in the Peace Park a tree, a symbol of life and respect for the environment, as a protest at the latest manifestation of the nuclear arms race, a Soviet underground test on Oct 4. IPPNW held its ninth World Congress from Oct 7 to 10. 2800 delegates from over seventy countries met at Hiroshima, not only to examine and re-evaluate the past but also to consider how to translate into practical action for the future the congress slogan "No More Hiroshimas". Never before can the location of a congress have been so appropriate to its theme. The conference centre was in the Peace Park, metres from the hypocentre, near the children’s monument to Sadako Sazaki (she of the paper cranes, who was exposed to the bomb at age 2 and died of leukaemia at 12) and right next to the Atomic Bomb Museum. To begin finding out about the effects of the "barbarous act" which "vapourised forever man’s sense of permanence", in Lown’s words, it was necessary only to look around. The museum alone, with its endless troupes of uniformed schoolchildren, some of them gasping and crying at the exhibits of charred clothing worn by their 1945 counterparts, contained more than enough evidence of the immediate effects of "Little Boy", the 15 kilotonne uranium bomb whose 3000°C heat near the hypocentre melted granite tombstones and blistered the stony face of a statue of Buddha. The congress also heard the testimonies of medical and nursing hibakusha, who had seen Hiroshima and Nagasaki, their destroyed and overwhelmed hospitals, their burned and radiation-sick people, with their own eyes.

Radiation Effects

Update

A scientific session was given over to the latest evidence from studies of the health effects of radiation at Hiroshima and Nagasaki (which was subjected to a plutonium bomb three days after Hiroshima)-mainly work from the Radiation Effects Research Foundation (RERF), supported jointly by the Japanese and US Governments. An important recent development is that estimates of the radiation doses experienced by inhabitants of both cities have been revised downwards. There were several reasons for this, explained by Dr Masahuru Hoshi of Hiroshima University, including the realisation that the iron casing of the Hiroshima bomb greatly reduced the amount of neutron radiation. A new dosimetry system was introduced in 1986 and is being further checked and refined. The implications of the revised dosimetry for calculating the relative risk for radiation-induced cancers were explained by Dr Yukiko Shimizu of RERF and Prof Joseph Rotblat, emeritus professor of physics, University of London. The relative risk given in the 1977 UNSCEAR report for leukaemia now has to be multiplied by 5, and that