703

MATERNAL SMOKING AND CANCER RISK TOOFFSPRING

SIR,-Dr Everson (July 19, p. 123) suggests that persons exposedtransplacentally to tobacco carcinogens may be at increased cancerrisk. This prompted us to examine our data on women smokers andcancer rates of children and young adults among the several ethnic

groups living in Hawaii. The data on smoking were obtained bypersonal interviews of over 5000 women, selected as a represent-ative population sample of the State during 1975-76. The cancerincidence rates were obtained using data from the State-widepopulation-based Hawaii Tumor Registry, in operation since1960. In the table, we present the ethnic-specific age and sexadjusted cancer incidence rates for all sites combined for persons age0-24 during 1973-77. Also presented are the ethnic-specific, age-adjusted percentages of women smokers, age 18-64 during1975-76. This age-range was chosen to include all women whowould be likely to have offspring age 0-24 during 1973-77.

AVERAGE ANNUAL AGE AND SEX ADJUSTED CANCER INCIDENCERATES FOR PERSONS 0-24 YEARS OF AGE IN 1973-77 AND AGE-

ADJUSTED PERCENTAGES OF WOMEN SMOKERS 18-64 YEARS OF AGEIN 1975-76 AMONG FIVE ETHNIC GROUPS IN HAWAII *

* World Standard Population used for age-adjustment.t Includes current and ex-smokers.

With the exception of the Chinese ethnic group (where thenumber of cancer cases was only 10 and the rate therefore unstable),we found good correlation between the percentage of womensmokers and the total cancer incidence rates among persons likely tobe the offspring of these women. Although these data offer onlyindirect support for Everson’s hypothesis, they do suggest the needfor further examination of the question of increased cancer riskamong offspring of smoking mothers.

Epidemiology Program,Cancer Center of Hawaii,University of Hawaii,Honolulu, Hawaii 96813, U.S.A.

M. WARD HINDSLAURENCE N. KOLONEL

SALT RESTRICTION IN HYPERTENSION

SIR,-For more than thirty years Belgian students of dietetics andmedicine have been taught the importance of salt restriction in thetreatment of hypertension and for general health. I was therefore alittle astonished by your view (Aug. 30, p. 459) that moderate saltrestriction, to 1000 mg a day, disturbs the patient. It is only a ques-tion of training. After a fortnight the patient usually has no furtherdifficulties. In fact, when our patients go to a cafeteria or hotel, theydislike the foods served and prepared in the ordinary way. When ahypertensive patient enters hospital our practice is to put him on a400 mg sodium diet; when he leaves the allowance is increased to1000 mg.You say that hypertension does not always respond beneficially.

This has less to do with the efficacy of salt restriction than with theway a patient adheres to the diet. In our experience, patientsinstructed by a dietician do better than those instructed by a physi-cian. It is a pity so many doctors ignore the beneficial effects of saltrestriction in hypertension-especially in view of the side-effects ofdiuretics and antihypertensive drugs.Dienst voor Inwendige Ziekten,9000 Gent,Belgium G. VERDONK

LYSINURIC PROTEIN INTOLERANCE

SIR,-Rajantie et al.l reported on a basolateral membrane

transport defect for lysine in lysinuric protein intolerance (LPI).They stated that, unlike other defects of intestinal and renalaminoacid transport, such as cystinuria and Hartnup disease, LPI isassociated with malnutrition and diarrhoea. They suggested thatthis disorder is due to a more severe or, perhaps, fundamentallydifferent defect. Increased renal clearance of affected aminoacidshas been shown in all three diseases.l,2 However, fasting plasmalevels of affected aminoacids in Hartnup disease and cystinuria havenot been appreciably lower than in controls, B4 contrasting withlowered fasting plasma levels of lysine in LPI. After dipeptide loadsin patients with cystinuria and Hartnup disease, plasma incrementsof affected aminoacids approximated to those of controls, 4,5suggesting that an oligopeptide pathway was available to maintainnutrition. Oral intake of dipeptide did not result in undue

discomfort,4,5 whereas patients with LPI had diarrhoea.Oral loads of lysylglycine showed much smaller increments in

plasma lysine in LPI, and increments were not larger after dipeptidethan after corresponding aminoacids. Plasma glycine incrementswere, however, as large in patients as in controls. The normaltransport of glycine from the dipeptide glycylglycine in these

patients, together with increased lysine accumulation in thesepatients, together with increased lysine accumulation in vitro inintestinal mucosal samples from patients, was taken to support adefective transport at the basolateral membrane in this disease,resulting in nutritional impairment.’ This is an important finding,and is added evidence of nutritional availability of peptides inHartnup disease where six essential aminoacids and in cystinuriawhere one essential aminoacid is defectively absorbed.’ Addedevidence that the defect is limited to the basolateral membrane maybe obtained by demonstrating normal tissue uptake of lysyllysine.Since peptide uptake appears to be shared by the same carriermechanism, lysyllysine uptake would be expected to be normal. If,however, uptake of lysyllysine is defective, uptake of glycine fromlysylglycine may have occurred via the glycine moiety, and in vitrotissue uptake of lysine may need to be confirmed.

Division of Gastroenterology,University of Arkansas forMedical Sciences,

Little Rock, Arkansas 72205, U S. A. FARHAD NAVAB

CLUMPING IN FAECAL VIRUS SPECIMENS

SiR,-Miss Roberts and her colleagues (July 19, p. 151) misin-terpret our findings (May 31, p. 1192). We did not claim that smallround viruses sediment effectively at low g forces unless

clumped-which frequently they are. However, viruses in therotavirus/adenovirus size range do to the extent that supernatantfrom spun tubes is virtually virus free. In work to be publishedelsewhere we show that clumping in fxcal specimens is due to localantibody secretion.

Public Health Laboratory,Institute of Pathology,General Hospital,Newcastle upon Tyne NE4 6BE

H. K. NARANGA. A. CODD

1. Rajantie J, Simmel O, Perheentupa J. Basolateral-membrane transport defect for lysinein lysinuric protein intolerance. Lancet 1980, i 1219-21

2. Milne MD, Asatoor AM. Peptide absorption in disorders of ammo acid transport.Peptide transport in protein nutrition. Amsterdam: Associated Scientific

Publishers, 1975: 167-823. Navab F, Asatoor AM. Studies on intestinal absorption of amino acids and a dipeptide

in a case of Hartnup disease. Gut 1970, 11: 373-794. Asatoor AM, Crouchman MR, Harrison AR, Light FW, Loughride LW, Milne MD,

Richards AJ. Intestinal absorption of oligopeptides in cystinuna. Clin Sci 1971; 41:23-33

5. Asatoor AM, Cheng B, Edwards KDG, Lant AF, Matthews DM, Milne MD, Navab F,Richards AJ. Intestinal absorption of two dipeptides in Hartnup disease. Gut 1970,11: 380-87.

6. Matthews DM. Intestinal absorption of peptides. Physiol Rev 1975; 55: 537-608