77

9. Holt, S. J , Epstein, M. A. Brit. J. exp. Path. 1958, 39, 472.10. Kidd, J. G. Bull. Johns Hopk. Hosp. 1948, 82, 583.

treatment of pellets obtained from uninfected chor-ioallantois failed to disclose D,X..B, The authors

conclude that the D.N.A. of infected gels is directlyconnected with cell infection by viruses. Thus inorder to study D.N.A. contained by viruses themselvesthe contaminating D.N.A. of host origin must be

excluded, and they suggest how this might be doneselectively leaving behind the virus nucleic acid 9.These structurally and chemically characterised

particles have also to be sought in cells of Roustumours as they occur in the fowl. They requireas well to be distinguished from, or identified with.other virus tumour particles that have been des-cribed -particularly those in association with mousemammary tumours. An extensive area of investi-

gation has been opened by the discovery of severalseparable agents obtainable under specific conditionsfrom certain mouse leukaemias and causing a varietyof tumours having conveniently short latent periods.The wealth of materials, methods, and tools now tohand may enable us to decide whether, like otherchemical or physical carcinogens, tumour viruses

merely initiate the malignant change, and thereafter,as suggested by KIDD 10, become passengers ratherthan the continuing cause of malignant proliferation.

Annotations

AN ELASTIC SHOESTRING

1. Report of the Medical Research Council for the Year 1957-58. Cmd. 792. H.M. Stationery Office, 1959. Pp. 288. 13s.The section on trends in medical research is to be publishedseparately on Aug. 17 under the title Current Medical Re-

search (3s. 6d).

’’DEPEND upon it, Sir, when a man knows he isto be hanged in a fortnight, it concentrates his mindwonderfully.’ Samuel Johnson’s words may partlyfit the Medical Research Council, which concentratesits mind wonderfully to fulfll its manifold tasks ona budget of some £3 million a year. But the M.R.C.shows no signs of impending dissolution. Far fromit: for, besides concentrating, it expands. The reportfor 1957-58, lately published’, tells how in that yearit set up a Population Genetics Research Unit (atOxford), a Microbial Genetics Research Unit (illLondon), and a group for Research on the ChemicalPathology of Steroids (at Sheffield).The use of the Council’s resources is determined in

two main ways: first by requests from Governmentaland other bodies for help on specifie issttes (thereport refers, for instance, to studies undertaken, atthe wish of the National Coal Board, on toleranceto heat in mines); and secondly by the Council’s owninitiative, wdiich accounts for by far the greater partof its work. Furthermore, through the Public HealthLaboratory Service, it engages in routine, as well asresearch, activities. Wisely the Council does notallow home needs ot prevent it from looking out-wards : it has units in Jamaica, Uganda, and theGambia ; and it is participating in important workon tuberculosis in the Tropics.

In the year covered by the report the net costof the National Health Service in Britain was £545million. The M.R.C. (which is financed not throughthe N.H.S. but mainly by Parliamentary grants—in—aid) is by no means the only body in this countrydedicated to medical research ; but the amount itreceived in that year, representing only 0,5 % of thecost of the Health Service, seems hardly a reasonable- and ultimately perhaps not even an economical-allotment.

SYSTOLIC MURMURS

1. Mainzer, W., Pincovici, R., Heymann, G. Arch. Dis. Child1959, 34, 131.

2. Lessof. M., Brigden, W. Lancet, 1957, ii, 673.3. Szabo, M., Ross, L. Dapim Refuum 1957, 16, 134.4 Messeloff, C.R. Amer. J. med. Sci. 1949, 217, 71.5. New York Heart Association, 1955, Nomenclature and Criteria

for Diagnosis of Diseases of the Heart and Blood Vessels,6. Wells, B. Brit. Heart. J. 1957, 19, 129.7. Leatham, A. Lancet, 1958, ii, 757.

SYSTOLIC murmurs may indicate organic heart-disease or may be the result of abnormal circul-atory states, as in anæmia and thyrotoxicosis; andmany are found in otherwise healthy persons. Inchildren it is usually a question of whether a, syst-olic murmur means heart-disease or not. Mainzeret al. 1 have recently examined 2035 children inIsrael, and found systolic murmurs in 240 (11.8%),which differs greatly from the 90 % found by Lessofand Brigden 2 in a smaller group in this country,but is not out of line with an earlier series 3 fromIsrael in which the incidence was only 9 9 cl’ C . Infact systolic murmurs seem relatively uncommonamong children in Israel for no very obvious reason.Mainxer and his colleagues were able to regard almosttwo-thirds of murmurs as innocent; in the remainingthird a positive diagnosis of organic heart-diseasewas made in only 8 cases, and in the others a heartlesion was either suspected or considered probablebecause of associated electrocardiographic or radio-graphic abnormalities. An interesting observation isthe frequent occurrence of murmurs in more thanone member of the same family, amounting to 40 oof the total, and a familial anatomical variation inone or other ventricular outflow tract may accountfor this. The main conclusion, however, is that thereis no characteristic of a systolie murmur itself whichguarantees innocence; site, intensity, and constancyor inconstancy all failed to distinguish betweenorganic and innocent murmurs. This finding con-firms previous opinions 4-5, and emphasises what’Yells has said: "The decision that a systolic mur-mur is innocent depends not only on the characterof the murmur itself, hut also on the absence ofany evidence of organic disease".

Disappointing though this may seem it is hardlysurprising when one considers the configurationof murmurs revealed by the phonocardiogram.Leatham 7 has shown that all systolic murmurs fallinto one of two groups, pansystolic murmurs andmidsystolic ejcetion murmurs. Those in the firstcategory begin at the first heart-sound and continuethroughout systole : they are regurgitant murmursdue to the bac1d1ow of blood either through incom-petent atrioventricular valves or through an abnor-mal communication as in ventricular sehtal defect.Murmurs of the second variety arc characterised bytheir short duration in midsystole and are caused bvforward flow through the aortic or pulmonary valves.Careful auscultation will usually distinguish the twotypes, but while pansystolic murmurs probablyalways indicate heart-disease, midsystolic murmursmay be the result of aortic or pulmonary stenosis,high-output states, or may be quite innocent. Thusthe recognition of a short midsystolic murmur mereryraises the possibility of its innocence, and the finaldecision depends upon a careful appraisal of othersigns. which include palpation of the heart, auscul-tation of the heart-sounds themselves, particularlythe second sound, and the electrocardiographic andradiographic appearances. Most important of all,no restriction should be placed upon any patient’sactivities unless the diagnosis of heart-disease isassured: in these circumstances it is probably betternot to err on the side of caution.