869

phenothiazine therapy is prolonged for years by manypsychiatrists with benefit and without significant ill-effect.

J. A. LYONS.Oakwood Hospital,

Maidstone,Kent.

SELENIUM CONTENT OF FISH FLOUR AND

KWASHIORKOR

J. C. WATERLOW.M.R.C. Tropical Metabolism

Research Unit,St. Mary’s Hospital, London, W.2.

SIR,-Professor Hadjimarkos (March 13) citesSchwarz’s trials 1 of selenium in children with kwashiorkorin Jamaica " which resulted in considerable weight gains ".This work has aroused comment, and therefore I thinkit necessary to make clear what happened.A collaborative trial was arranged with Dr. Schwarz in which

we tried to test the effect of supplementary selenium on the rateof recovery in patients with kwashiorkor. We cannot withholdmilk from these patients, and obviously the test will only havemeaning if it is made in children who are failing to respond tothe normal dietary treatment. Two such cases were studied upto the time of Dr. Schwarz’s publication. At the same time anattempt was made to measure selenium intake and output as acheck on whether there was a deficiency, but I understood fromDr. Schwarz that the analytical method for selenium gaveunreliable results, and therefore we could obtain no guidancefrom these measurements. From my experience of the variedpatterns of response to treatment in children recovering fromkwashiorkor, I do not think it is justifiable to conclude from theweight gains alone that the selenium supplement had anybeneficial effect. The publication of the results in these twocases was made without consultation with me.

M.R.C. Tropical MetabolismResearch Unit, J C WSt. Mary’s Hospital, London, W.2... WATERLOW.

* * * We regret that on the contents page of our issue ofMarch 13 Professor Hadjimarkos was incorrectly titled.- end. L.

THE SMALLER OF TWINS AND

HYPOGLYCÆMLA

SIR,-Dr. Reisner and his colleagues (March 6) showthat the smaller baby of a twin pair shows a high frequencyof early hypoglycasmia. Two conclusions in their sum-

mary demand comment:

1. That " hypoglycaemia is ... a possible xtiological factorfor the mental subnormality and slow development seen in thesmaller twin as compared with his larger sibling ". Of the 11pairs presented (in which the smaller twin had hypoglycasmia)6 pairs developed equally. The history of the other 5 pairs wasas follows: the " unaffected " twin was smaller and stillborn;the smaller twin was greatly retarded at a year while the largerhad arrested hydrocephalus; the smaller twin died from myelo-meningocele and meningitis, the other’s fate being unknown;the smaller twin was normal at 21/2 years, and the larger diedon the 2nd day of the respiratory-distress syndrome; and 1 pairwas " lost to follow-up ". In the series there are no within-pair differences which will support this first conclusion.The smaller twins were investigated for hypoglycxmia and

found to have low blood-sugar values because, as individuals,they presented with signs and symptoms ofhypoglycasmia (with29 other, single-birth babies). It would be interesting andimportant to know the blood-sugar values of the larger twins.

2. That " the smaller twin is thought to be an example ofintrauterine malnutrition with the larger twin as a naturalcontrol for their period of gestation ". 2 pairs were clearlydizygous (being of different sex). Of the remaining 9 pairsof like sex, there would have been three likely potentialtypes of placentation: dizygous twins with dichorionic diam-niotic placentae; monozygous twins with monochorionicdiamniotic placentae ; and monozygous twins with dichorionicdiamniotic placentae. We are not clear what is meant by a " natu-ral control", but we think that only if the twins were monozy-gous, and hence genetically identical, are within-pair differences

1. Schwarz, K. Fed. Proc. 1961, 20, 666.

significant when related to prenatal environment (" nutrition ").There is an interesting yet complex factor in monochorionicdiamniotic placenta: since all degrees of circulatory anastomosesoccur; and the mass of one part of the placenta supplying onetwin is very highly correlated with the birth size of that twin.1Thus it becomes important to know data on the zygosity of thetwins and their placentae.The mean birthweight of these smaller twins was 1440 g.

(range 927-2310 g.). Any subsequent development patternmay also be associated with simply being an infant of lowbirthweight. The larger twin’s mean birthweight was 2028 g.(range 910-2690 g.) including the stillbirth, and 2139 g. (range1604-2690 g.) excluding the stillbirth. Among aetiologicalfactors, multiple pregnancy is associated with infants of lowbirthweight and discrepancies of gestational age/size. Clearlythe level of birthweight in a low birthweight group is important.Without more data the use of the twin method here

appears to be unsound.

FRANK FALKNER.Department of Pediatrics,

University of Louisville School of Medicine,Louisville, Kentucky, 40202.

1. Falkner, F. Ann. N.Y. Acad. Sci. 1965 (in the press).

Public Health

Infectious Diseases in England and Wales

Diary of the Week

APRIL 18 TO 24

Monday, 19thGLASGOW POSTGRADUATE MEDICAL BOARD

11.50P.M. Grampian Television: Backache.

Tuesday, 20thASSOCIATION FOR THE STUDY OF MEDICAL EDUCATION

1.25 P.M. (B.B.C. Medicine Today): Lord Brain, Dr. Frank Cooksey:Pain in the Arm. Dr. R. P. C. Handfield-Jones: DomiciliaryObstetrics.

Wednesday, 21stOPHTHALMOLOGICAL SOCIETY OF THE UNITED KINGDOM

10 A.M. (Royal College of Physicians, 11, St. Andrews Place, London,N.W.I). Opening of 3-day meeting.

Thursday, 22ndPOSTGRADUATE MEDICAL SCHOOL OF LONDON, Ducane Road, W.12 2

4 P.M. Dr. G. R. Blagg: Dialysis in Chronic Renal Failure.ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE, 26, Portland Place,

London, W.17.30 P.M. Dr. M. Yoeli: Plasmodium berghei in Nature and under Experi-

mental Conditions.

Friday, 23rdROYAL COLLEGE OF SURGEONS OF ENGLAND, Lincoln’s Inn Fields, W.C.2

5.30 P.M. Prof. Kurt Clippers : Reflections on the Possibility of influencingthe Pathological Fixation Act. (Edridge-Green lecture.)

POSTGRADUATE MEDICAL SCHOOL OF LONDON10 A.M. Prof. C. V. Harrison: Head and Neck Malignant Disease.