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a little beyond them, and this will take time to form. Acareer structure needs an academic structure, and alsoa financial structure: the college might tackle the former,but the latter requires the help and blessing of the

Ministry. None the less the college is right to state what,in its view, is the best training for the general practi-tioner of the future, regardless of whether or not the idealcan yet be achieved. For, if future practitioners were toreceive a proper graduate training, " there is no doubt ",as Sir Robert Platt says, "that the whole status of generalpractice would improve, and the public would have directaccess to a higher quality of medical care ".

VARIETIES OF GLUCOSE-6-PHOSPHATE

DEHYDROGENASE

THE discovery that people who are prone to haemolysisafter taking primaquine and certain other drugs have lowlevels of glucose-6-phosphate dehydrogenase (G.-6-P.D.)in their red cells 2 opened up an important area of investi-gation. It soon became apparent that the type of enzymedeficiency found in Africans is distinct from that inMediterraneans. In haemolysates of drug-sensitive personsof African origin, G.-6-P.D. activity is about 10-20% ofnormal, whereas in those of Mediterranean descentactivities are usually less than 5%.3 4 Normal and sensi-tive Africans do not differ in the enzyme activities of their

leucocytes, liver-cells, and skin-cells,5 6 although suchdifferences have been found in the lens of the eye. In

subjects of Mediterranean origin G.-6-P.D. deficiency hasbeen demonstrated in leucocytes, blood-platelets, saliva,liver-cells, and cultured skin-cells .6 a

It has also been found that the African type of deficient

enzyme has a relatively high electrophoretic mobility atalkaline pH, similar to that of the A type of enzyme whichis present in about 20% of normal African subjects.9 9 10The Mediterranean type of deficient enzyme has a lowerelectrophoretic mobility, similar to the B type of enzymefound in nearly all Caucasians, and in about 80% ofAfricans.On p. 932 Dr. Stamatoyannopoulos and his colleagues

report another type of enzyme deficiency in Mediter-raneans. The deficiency is milder than the classicalMediterranean type, activities of G.-6-P.D. ranging fromthe very low level of 5% of the mean to 75%, which isclose to the lower limit of normal. About 15% of allenzyme-deficient male Greeks manifest the mild type,which is commoner in some parts of Greece than others.From this fact, and the mode of inheritance, it seems thatthe mild type of Mediterranean deficiency represents adistinct mutation. The electrophoretic mobility of themildly deficient enzyme is of the normal B type.

In addition to these varieties of enzyme deficiency,which are relatively common in certain populations, anumber of rare variants of G.-6-P.D. have been found.These are not necessarily associated with low enzymeactivity: the Baltimore, Ibadan, and Sardinian types ofenzyme, which have characteristic low electrophoretic1. Doctor and Patient; p. 50. London, 1963.2. Carson, P. E., Flanagan, C. L., Ickes, C. E., Alving, A. S. Science, 1956,

124, 484.3. Marks, P., Gross, R. T. J. clin. Invest. 1959, 38, 2253.4. Choremis, C., Kattamis, C., Zannos-Mariolea, L., Paraschopolou-

Prevedouraki, P. Brit. med. J. 1963, ii, 1240.5. Marks, P. A., Gross, R. T., Hurwitz, R. T. Nature, Lond. 1959, 183, 1266.6. Gartler, S. M., Gandini, E., Ceppellini, R. ibid. 1962, 193, 602.7. Zinkham, W. H. Bull. Johns Hopk. Hosp. 1961, 109, 206.8. Ramot, B., Fisher, S., Szeinberg, A., Adam, A., Sbeba, C., Gafni, D.

J. clin. Invest. 1961, 38, 1659.9. Boyer, S. H., Porter, I. H., Weilbacher, R. C. Proc. nat. Acad. Sci.,

Wash. 1962, 48, 1868.10. Kirkman, H. N. Amer. J. Dis. Child. 1962, 104, 566.

mobilities, show G.-6-P.D. activities in the normal range."However, analysis of enzyme-deficient Caucasian subjectsnot of Mediterranean origin, many with associated con-genital nonspherocytic hasmolytic anaemia, has revealed aheterogeneous group of conditions. The Oklahoma typeof deficient enzyme is thermolabile, with normal electro-phoretic mobility, high Michaelis constants for G.-6-p.and nicotinamide adenine dinucleotide phosphate (N .A.D.P.),and narrow pH-activity curve. 12 The Chicago type ofdeficient enzyme is extremely thermolabile but otherwiselike the normal enzyme.12 The Eyssen type of enzyme 9 11is thermolabile, with an electrophoretic mobility inter-mediate between the A and B types. The Barbieri type 13is associated with mild enzyme deficiency and no anaemiain subjects of Italian origin; the enzyme has a high electro-phoretic mobility. The Seattle type of enzyme deficiency 12was found in a non-anxmic person; the electrophoreticmobility is much lower than normal.

It is thus clear that many varieties of G.-6-P.D. deficiencyexist, some common in certain populations and others rare.The situation is reminiscent of the abnormal haemoglobins,and the considerable amount of work now being done willdoubtless reveal much more variation.

STRONTIUM-90 IN BONE

FIGURES 14 for the second half of 1963 show a furtherincrease in the level of strontium-90 in bone samplesassayed at Woolwich and Glasgow. The collection of

samples was again arranged to include a high proportionof bones from individuals who had lived in areas of heavyrainfall. Between July and December, 1963, the stron-tium-90 concentration in bone increased in all age-groups.In newborn and stillborn infants the mean level (of 97samples) was 2-98 pC per g. Ca, compared with 1.36

(from 74 samples) in the corresponding months of 1962.In children from the age of 14 days to 1 year the mean

figure (from 60 samples) was 6-25 pC per g., against 2-41(from 70 samples) in July-December, 1962 (the agestructure of this second group may vary considerablybetween one six months and another).These findings are in general accord with the predic-

tion of possible future levels by the M.R.C. committeelast February. 15 The " maximum permissible levels "have been set at 200 pC per g. for individuals and 67 pCper g. for the average over the whole population. Thecommittee said the available evidence then suggestedthat bone levels in 1964 " may be of the same order asin 1963, but should decrease thereafter ".

MORE ABOUT SHEEPSKINS

IN 1961 Ewing and his colleagues in Melbournedescribed 16 the use of sheepskins as a nursing aid. Theyemphasised the comfort for the patient and the preventionof pressure sores. We are informed that a number of

geriatric departments in this country have confirmed thatthe sheepskin contributes usefully to the patient’s com-fort, but no clear evidence has been forthcoming that it

prevents pressure sores. Moreover, the sheepskins used11. Porter, I. H., Boyer, S. H., Watson-Williams, E. J., Adam, A.,

Szeinberg, A., Siniscalco, M. Lancet, 1964, i, 895.12. Kirkman, H. N., Brinson, G. A., Pickard, B. M. Proceedings of 9th

Congress of European Society of Haematology, Lisbon, 1963; sectionVII. Basle, 1963.

13. Marks, P. A., Banks, J., Gross, R. T. Nature, Lond. 1962, 194, 454.14. Assay of Strontium-90 in Human Bone in the United Kingdom Results

for 1963, part II. Medical Research Council Monitoring Report Seriesno. 9. H.M. Stationery Office. Pp. 17. 2s.

15. See Lancet, 1964, i, 420.16. Ewing, M. R., Garrow, C., McHugh, N. Lancet, 1961, ii, 1447.