1025

ALUMINIUM CONTENT OF INFANT FORMULAE

The Al content seemed to be lowest in breast milk and highest insoy-based formula. Interestingly, however, the concentration was3-100 times higher in conventionally prepared formulae than whenthe aluminium-free method was used (table). The mode ofpreparation should therefore be borne in mind when Al levels insuch formulae are being studied.

Department of Paediatrics,and Laboratory of Internal Medicine,

St Radboud University Hospital,6500 HB Nijmegen, Netherlands

B. A. SEMMEKROTL. A. H. MONNENSH. BAADENHUYSEN

SCANDAL IN SOUTHWARK

SiR,—Your April 15 note (p 856) is about unethical experimentson dying patients in a private London hospital. Whilst I do notapprove of the so-called research and consider it to be unethical, Iam concerned about the statement that "Non-NHS hospitals arenot legally bound to have an ethics committee". Are NHS hospitalsso bound? Despite more than 15 years of writing and lecturing onthis subject, I have not come across legal requirements that any UKhospital must have an ethics committee or that a doctor must submita research protocol to such a committee. There may be, of course,other methods of ensuring these requirements, but none fall withinthe remit of UK civil or criminal law. Perhaps now is the time topress for such a law.

100 Denham Lane,Chalfont St Perer, Bucks SL9 OQJ B. T. MARSH

ADOPTIVE IMMUNOTHERAPY

SiR,—The use of adoptive immunotherapy, as a valid medicalresearch treatment in a variety of disorders, has been widelypublished.l.2 Indeed, a Lancet editorial said, in the context of cancer,"the outlook is bright". Your note entitled Scandal in Southwark(April 15, p 856) seems to overlook this.While it has been unusual for new investigational work to be done

in the private sector in the UK this situation, in view of presenttrends, is unlikely to persist. There is now every precedent foroffering experimental treatment to private patients, under the usualcircumstances of cost recovery.

Ethical approval for the treatment with adoptive immunotherapyof patients with leukaemia was provided by King’s College Hospitalin 1984. London Bridge Hospital’s medical advisory committeemonitored my programme in 1987 and 1988 and concluded in thesummer of 1988 that further monitoring was unnecessary. Anotherprivate London hospital, in the summer of 1988, gave me ethicalapproval for the continued use of this treatment.We have used autologous and allogeneic activated cells without

systemic lymphokines as our form of adoptive immunotherapy.The results indicate that, of the malignancies, haemopathies may beespecially responsive.4 The role of adoptive immunotherapy in HIVinfection requires further evaluation.5 No major toxicity has beenencountered.

Every patient entering the programme was interviewed by meand informed of the experimental nature of the treatment. The use

of immunomanipulative techniques in biomedical research andclinical practice is likely to become more common.2,3,6 Your articleshould be viewed in the light of this trend rather than investigativereporting in a weekly magazine. Ethical committee approval,informed consent, and compassionate clinical care must continue toprovide the framework upon which therapeutic advances are made,whether in the private or public sector.

139 Grove Lane,London SE5 8BG JAMES SHARP

1. Rosenberg SA, Lotze MT, Muul LM, et al. Observations on the systemicadministration of autologous lymphokine activated killer cells and recombinantinterleukin 2 to patients with metastatic cancer. N Engl J Med 1985; 313: 1485-92.

2. Editorial. Immunological treatment for multiple sclerosis. Lancet 1989; i: 699-701.3. Editorial. Interleukin 2 sunrise for immunotherapy? Lancet 1989; i: 308.4. Sharp JC. Activated cell treatment in malignant disease. Cancer Detect Prev 1989; 14:

126.

5. Sharp JC Activated cell treatment in HIV infections. Cancer Detect Prev 1989; 14:118.

6. Sharp JC. Activated allogeneic and autologous cells in the treatment of malignantdisease: the implications of cytotoxic and tolerance effects. Biomed Pharmacother (inpress)

WHEN DID I BEGIN?

SIR,-When did I Begin? is the question posed by the bookreviewed by Dr Chambers (March 11, p 526). R. V. Short, FRS,professor of reproductive biology, Monash University, Australia,discussing the diversity of mechanisms of reproduction in mammalsstates: "The only common factor is that, somewhere along the line, aspermatozoon meets an egg and so a new individual is formed".l

79 St Mary’s Road,Liverpool L36 5SR

PEGGY NORRIS,Hon secretary, Medical Education Trust

1 Austin CR, Short RV, eds. Reproduction in mammals vol IV, 2nd ed Cambridge:Cambridge University Press, 1984: 24

IN-VITRO FERTILISATION AND SEX RATIO

SIR,-In 100 consecutive live births after in-vitro fertilisation(IVF) at Yale University there was a preponderance of male infants,the sex ratio being 1 ’83 as opposed to the expected 1-06 (p < 0-01).

Since 1982 we have been using essentially the same protocol forfollicular augmentation, sperm separation, and culture, and

throughout this period the live birth rate and the sex ratio haveshown little variation. The ovarian stimulation protocol used in 95of 100 cycles that resulted in a pregnancy consisted of 225 IU ofhuman menopausal gonadotropin (hMG) from cycle day 3 for 5-7days. This is a more aggressive regimen than that used by manyother centres and may result in higher oestradiol levels and/orearlier human chorionic gonadotropin (hCG) injections. Severalstudies have shown that sex ratio is altered with higherconcentrations of sex steroids after clomiphene or hMG-but,when found, this alteration is usually in favour of increased femalebirths.’ Other studies have shown no association with clomiphene2or gonadotropin stimulation.34 With our protocol there is rapidfollicle growth, such that hCG is injected several days in advance ofthe luteinising hormone surge in natural cycles and earlier than inprotocols with less vigorous stimulation (table). Alterations in sexratio have also been linked to variation in day and type ofinsemination.’

Y-bearing sperm have been reported to cross cervical mucusmore quickly than X-bearing sperm. This motility characteristicmay be reflected in oocyte penetration too. Alternatively, alterationsin the oocyte-cumulus complex may mean that there is selectivefertilisation by Y-bearing sperm.Our laboratory staff changed several times over the study period,

but the technique of sperm preparation and culture remained thesame. We use a wash and swim-up incubation technique that selectsthe most motile sperm for insemination. This procedure involvessemen collection on the premises with the first sperm wash

beginning within an hour of collection. The swim-up technique isdone twice in Ham’s medium, after which insemination is done at aconcentration of 50 000 sperm in 0 1 ml per oocyte. Protocols thathave isolated Y-chromosome bearing sperm gradients have beenreported.8 A tremendous effort has been applied to preselection of

1026

CHARACTERISTICS OF IVF CYCLES BY SEX OF OFFSPRING

Y-bearing sperm, perhaps we have done this inadvertently. Rawlinset al9 identified a rich Y-bearing lower fraction after a spermseparation technique very similar to that in our protocol.Age has been associated with a higher chance for a female child

and this might be expected to happen in clinics where the averagematernal age is in the 30-35 year range, yet the opposite result wasfound (table). Nor was there any difference in parity or sex ofprevious births. Although the primary sex ratio of conceptions is notknown, it appears that considerably more males are conceived thanfemales since the sex ratios of abortuses is 1 6. IVF may bypass somenatural regulatory mechanism allowing a closer approximation tothe primary sex ratio. If this were so, sex ratios would be altered inall IVF centres, but no general alteration in sex ratio at birth hasbeen reported. 10-12

Division of Reproductive Endocrinology,Department of Obstetrics and Gynecology,Yale University School of Medicine,New Haven, Connecticut, USA

SAMUEL S. THATCHER*UMBERTO RESTREPOGAD LAVYALAN H. DECHERNEY

*Present address: Department of Obstetrics of Gynecology, East Tennessee State

University College of Medicine, PO Box 19570A, Johnson City, Tennessee 37614, USA.

1. James WH The sex ratio of infants born after hormonal induction of ovulation. Br JObstet Gynaecol 1985; 92: 299-301.

2. Sampson JH, Alexander NJ, Fulgham DL, Burry KA. Gender after artificial

induction of ovulation and artificial insemination. Fertil Steril 1983; 40: 481-84.3. Ben-Rafael Z, Matalon A, Blankstein J, Serr DM, Lunenfeld B, Mashiach S. Male to

female ratio after gonadotropin-induced ovulation. Fertil Steril 1986; 45: 36-40.4. Cholst I, Jewelewicz R, Dyrenfurth T, Vande Wiele L. Gonadotropins and the human

sex ratio. Br Med J 1981; 283: 1264.5. Guerrero R. Association of the type and time of insemination within the menstrual

cycle with the human sex ratio at birth N Engl J Med 1974; 291: 1056-59.6. Harlap S Gender of infants conceived on different days of the menstrual cycle N Engl

J Med 1979; 300: 1445-48.7. France JT, Graham FM, Gosling L, Hair PI. A prospective study of the preselection

of the sex of offspring by timing intercourse relative to ovulation. Fertil Steril 1984;41: 894-900.

8. Iizuka R, Kaneko S, Aoki R, Kobayashi T. Sexing human sperm by discontinuousPercoll density gradient and its clinical application. Hum Reprod 1987; 2: 573-75.

9. Rawlins RG, Sachdeva S, Radwanska E, Binor Z, Rana N, Dmowski WP Human sexpreselection and in vitro fertilization (IVF): fraction separation of sperm enhancesprobability of conceiving male offspring. 35th annual meeting of the Society ofGynecologic Investigation (Baltimore, March 17-20, 1988).

10. Edwards RG, Fishel SB, Cohen J, et al. Factors influencing the success of in vitrofertilisation for alleviating human infertility. J In Vitro Fertil Embryo Transfer 1984;1: 3-23.

11. Garcia J, Jones GS, Acosta AA, et al. In vitro fertilization in Norfolk, Virginia,1980-1983. J In Vitro Fertil Embryo Transfer 1984; 1: 24-28.

12. Trounson A, Wood C. In vitro fertilisation results, 1979-1982, at Monash University,Queen Victoria, and Epworth Medical Centres. J In Vitro Fertil Embryo Transfer1984; 1: 242-47.

INFLUENCE OF ZIDOVUDINE ON PROGRESSION TOAIDS IN COHORT STUDIES

SiR,&mdash;A critical question about HIV is how many of thoseinfected will progress to AIDS and how quickly. The question is thesubject of several prospective studies,l-4 and modelss’ have beengenerated to describe the natural history of HIV infection. Theanswer has implications not only for individual patient managementbut also for epidemiological forecasting. A recent slowdown in therise in numbers of new AID S cases in our prospective study8 causedus to wonder whether we (and others) in our studies of the natural

Progression to AIDS, predicted and actual.

- =predicted progression to AIDS derived from first 60 months offollow-up on Weibull model in which cumulative rate at t months is given asl-exp[-(O’OO9 t)275].

- - - = actual Kaplan-Meier progression curve through 88 months.

history of HIV infection might now be observing the unnaturalhistory of this disease.A cohort of over 700 homosexual men recruited from six primary

care practices in central Vancouver between November, 1982, andFebruary, 1984, contains 351 who are seropositive (233 at

enrolment [seroprevalent] and 118 seroconverters during follow-up[seroincident]). Because date of infection is unknown in the

seroprevalent cases, we first estimated a median of 18 months ofinfection before enrolment, on the basis of progression of laboratoryindices. Time zero was therefore taken to be the midpoint betweenthe last negative and positive result for seroincident cases and 18months before the first positive result for seroprevalent cases.Follow-up for the development of AIDS was achieved throughannual visits and by record linkage with the national registry at theCanadian Federal Centre for AIDS. Following other investigators5-7we fitted a Weibull model to the first 60 months of follow-up andextended it to 88 months to obtain the predicted AIDS progression.The progression curve to 88 was obtained by the Kaplan-Meiermethod, AIDS-free men being right censored at Dec 31, 1988.By Dec 31, 1988, there were 69 cases of AIDS in this cohort (59

seroprevalent; 10 seroincident). The Weibull model (figure)predicts a cumulative progression to 41 % by 88 months, in keepingwith published studies.2,6 However, the AIDS progression curveobserved diverged from this curve after 70 months for a cumulativeAIDS progression to only 28% at 88 months (95% confidenceinterval 21 % to 34%). Even when the analysis was repeated with amore conservative assumption of only 12 months of lead timeinfection for seroprevalent cases significant divergence was still

present.In July, 1987, the criteria for zidovudine therapy in Canada were

expanded to include Centers for Disease Control groups IV-C1 andIV-C2 besides infected people considered to be at grave risk ofdeveloping an opportunistic infection as suggested by depressedCD4 counts (generally below 300/il). Our hospital pharmacy is theonly source of zidovudine in British Columbia, through linkagewith the pharmacy records and chart review we identified 61 men inthe cohort who began therapy between January, 1987, andDecember, 1988. 27 began therapy after the diagnosis of AIDS,which would not affect progression. Of the other 34 men only 2 haveprogressed to AIDS. The mean time to initiation of therapy in these34 was 63-4 (SD 19-0) months. This coincides with the time periodin which the deflection of the curve becomes apparent.

In summary, our cohort has followed classic AIDS progressionin the first 60 months offollow-up.2-4.6 There appears, however, tohave been a deviation away from this progression pattern due to arecent shortfall in new AIDS cases. We speculate that the mostlikely cause is the postponement of AIDS in men with advancedHIV infection who have received or are receiving zidovudine, an