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Research takes off into space

How human beings, who are (normally)terrestrial creatures, are able to adapt withapparent ease to the weightlessness of spaceis being addressed by the second US spaceshuttle mission on life-sciences research.

During the 14-day voyage taking place 176miles above the earth’s surface, ex-

periments will be done on the 7 crew

members and 48 rats to investigate thephysiological responses to microgravity-the decrease in exercise capacity of theheart; muscle atrophy; fluid shift to thehead; bone demineralisation; reduction inerythropoiesis; and space sickness. :

Cardiovascular deconditioning in spaceleads to orthostatic hypotension on returnto earth. Redistribution of body fluids tothe head during weightlessness induces aninappropriate fluid loss, together with a60% increase in stroke volume. Ex-

periments will be undertaken at rest andduring bicycle exercise to measure theearliest changes to peripheral resistance.Central venous pressure will also be

measured, and echocardiographic (leftventricular end-diastolic volume increasesin space) and blood flow data will becollected.

Weightlessness might be expected to

distribute air and blood evenly in the lungs.Why, as found in the June, 1991, mission,these effects are only half of what one wouldexpect is to be investigated further. :

Space flight anaemia is a consistentfinding among astronauts. During thisflight, rats will be infused with erythro-poietin and the effect on blood, bonemarrow, thymus, and spleen will be exam-ined. Red-cell kinetics will be studied increw and rats. :Changes in fluid balance will be investi-

gated by measuring glomerular filtrationrate, plasma volume, and extracellular fluidvolume. Crew members will drink 180- :

labelled water so that total body watercontent can be measured. :Calcium metabolism will be studied in

rats through assessment of their osteoblastfunction and their excretion of labelledcalcium. Crew members will have theirintestinal calcium absorption and boneturnover estimated from blood and urineconcentrations of vitamin D metabolitesand calciotropic hormones after admin-istration of two stable calcium isotopes. :Most of the muscle atrophy occurring

during spaceflight is from posturalmuscles. Whole-body protein metabolism

will be assessed by measuring 15N-glycinein blood and urine specimens of crew

members. Results from the 1991 life-

sciences mission suggested that a substan-tial stress response may contribute to this

process. The effects of weightlessness onmuscle will be studied by electron micro-scopy, histological staining, proteasemeasurements, and metabolic experimentson rat hindlimb muscls.

Nausea, vomiting, and loss of balance arecommon complaints of those who undergospace travel. Structural changes over timeto the otolith organs of the inner ear will be

sought in rats by means of electron micro-scopy and computer reconstruction of theeffects of microgravity. Crew members willhave their nystagmus responses checked ina manually rotating chair. Neck-muscle

activity, the degree of head rotation, andeye movements will all be recorded. To

help study eye rotation, every subject willwear a marked contact lens. Spinal reflexes,positional sense, and susceptibility to

motion sickness will also be investigated.In addition to the 2 pilots and 4 scientists,

a vet has been included in the crew-thefirst in any space mission. The shuttle is

expected to land at Edwards airforce base inCalifornia on Nov 1.

Richard Horton

Cluster of Sellafield

reports

"The relationship with radiation in thenon-Seascale part of the study population isat best weak, and arguably non-existent",says the UK Government’s Health andSafety Executive in a case-control study’ ofleukaemia and other cancers in the childrenof men who had worked at Sellafield, thenuclear plant in West Cumbria. For familyresidence in the village of Seascale only, theHSE affirmed a statistical link between

fathers’ preconception dose and leukaemiaor non-Hodgkin lymphoma (NHL) in off-spring. The ratio of observed (6 cases) toexpected cases was about 14 times nationalincidence, with a 95% CI of around 2 to 25on the odds ratio. :

On Oct 8, a judge dismissed two claimsthat radiation from the site had causedcancer in offspring (see Lancet Oct 16,p 981). In the following week, LouiseParker and colleagues (two of whom workfor British Nuclear Fuels)2 reported: "The[geographic] distribution of the paternalpreconceptional radiation dose is statis-

tically incompatible with this exposureproviding a causal explanation for thecluster of childhood leukaemia in Sea-scale".The HSE investigation was prompted by

the 1990 report by the late Prof Martin ’,Gardner, who suggested the paternal pre-

conceptional link. From the same HSE

report, British Nuclear Fuels concludedthat the Gardner association "doesnot work", while Friends of the Earthsaid that "Sellafield remains the mostconvincing explanation for the leukaemiaexcess". :The day after the HSE report, a meeting

was held in London in honour of Gardner.Stephen Evans, professor of medical statis-tics at London Hospital Medical Collegeand an expert witness in the hearing, wasscathing about the judge’s criticisms. Theassociation was based on a small number of

cases, he agreed, but this was of little publichealth importance. Prior knowledge of theSeascale cluster was irrelevant in a case-control study. A change in the Gardnercriteria to include cases born and diagnosedin West Cumbria was not made with

knowledge of doses; investigation of thoseborn in the region was the first of anintended series of studies. Bias caused bythe inclusion of the so-called Bristol caseand the effect of multiple hypothesis testingwere matters for dispute. Evans refuted thejudge’s suggestion that untraced fatherswere included by Gardner. Peter Smith,London School of Hygiene and TropicalMedicine, looked at other explanations. Asdid the HSE report, he discussed thealternative hypothesis on population-mixing. :

: The Sellafield findings are historic, be-cause the effect is associated with startingwork there before 1965, and present allow-

able exposures are much reduced. The

HSE concluded that no extra measures are

required to protect employees.

David McNamee

1 HSE investigation of leukaemia and othercancers in the children of male workers atSellafield. Available from HSE Books,PO Box 1999, Sudbury, Suffolk CO10 6FS,UK. ISBN 0717606597. £20.00.

2 Parker L, Craft AW, Smith J, et al.Geographical distribution ofpreconceptional radiation doses to fathersemployed at the Sellafielld nuclearinstallation, West Cumbria. BMJ 1993; 307:966-71.

Pinocchio syndrome

In Collodi’s fairy tale, Pinocchio’s nosegrew longer each time he told a lie. A reportfrom Strasbourg, France, describes a 51-year-old man with an unusual reflex epi-lepsy : he had seizures when he told lies.’The lies were, the authors note, told for"business reasons" (the patient was a nego-tiator with the European Community). Hisseizures ceased after removal of a right-sided cavernous sinus meningioma.

John Bignall

1 Sellal F, Chevalier Y, Collard M."Pinocchio syndrome": a peculiar form ofreflex epilepsy. J Neurol NeurosurgPsychiatry 1993; 56: 936.