Dietary effects on breast cancer

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disease patient; our experience with apomorhine in disease has taught us that separation between the sedative effect and a primary action on movement disorders is difficult but not impossible.8

Huntington’s Huntington’s

Bernard B Brodie Department of Neurosciences, University of Cagliari,

09124 Cagliari, Italy

GIAN LUIGI GESSA ANTONIO CANU MARIA DEL ZOMPO CATERINA BURRAI GINO SERRA

Tamminga CA, Schaffer MH, Smith RC, Davis JM. Schizophrenic symptoms improve with apomorphine. Science 1978; 200: 567-68. 2. Vasavan Nair NP, Bloom DM, Nestoros JN. Cholecystokinin appears to have antipsychotic properties. Prog Neuro-Psychopharmacol Biol Psychiatry 1982; 6: 1.

509-12.

Moroji T, Watanabe N. Aoki N, Itoh S. Antipsychotic effects of ceruletide (caerulein) on chronic schizophrenia. Arch Gen Psychiatry 1982; 39: 485. 4. Neborsky R, Janowsky D, Munson E, Depry D. Rapid treatment of acute psychotic symptoms with high and low-dose haloperidol. Arch Gen Psychiatry 1981; 38: 3.

195-99. 5. Iorio LC, Barnett

A, Leitz FH, Houser VP, Korduba CA. SCH 23390, a potential benzazepine antipsychotic with unique interactions on dopaminergic systems. J Pharmacol Exp Ther 1983; 226: 462-68. 6. Farde L, Halldin C, Stone-Elander S, Sedvall G. PET analysis of human dopamine receptor subtypes using 11C-SCH 23390 and 11C-raclopride Psychopharmacology 1987; 92: 278-84. 7. Morelli M, Di Chiara G. Catalepsy induced by SCH 23390 in rats. Eur J Pharmacol 1985; 117: 179-85. 8. Corsini GU, Onali PL, Masala C, Cianchetti C, Mangoni A, Gessa GL. Apomorphine hydrochloride-induced improvement in Huntington’s chorea. Arch Neurol 1978; 35: 27-30.

antibodies can accumulate at the site of infection and are detected by scintigraphy. Accumulation of labelled antibodies at the site of infection did not seem to be prevented by interference from normal circulating immunoglobulin molecules. The common denominator of these studies is that immunoglobulins that show a beneficial effect or accumulate at the site of infection differ from venous immunoglobulins. The former antibodies had undergone an isolation procedure whereas the latter had not. The isolation procedure might have modified the immunoglobulin in such a way that it was able to accumulate at the site of infection. Native-not isolated-immunoglobulins lacked this property to a large extent. The fact that multivalent IgM behaves better than IgG indicates that it reacts with bacteria having multiple identical epitopes. Ziegler et aP showed that monoclonal antibody was effective only in patients with a gram-negative infection. This indicated that not only changes in the non-Fab part of the antibody endow it with its beneficial effect, since the antibody was effective only in patients in whom gram-negative bacteria are implicated. The beneficial effect of human monoclonal antibody in the treatment of gram-negative infection seems to result from binding of the Fab part of the antibody molecule to bacteria together with a subtle change in the non-Fab region caused by the isolation procedure. Blauwkapelseweg 61, 3572 KC Utrecht, Netherlands

Couwenhoven 50-12,

AD FLUIT

Zeist

1.

Mechanism for monoclonal antibody mediated treatment of gram-negative shock

RUURD TORENSMA

Ziegler EJ, Fisher CJ Jr, Sprung CL, et al. Treatment of gram-negative bacteremia and septic shock with HA-1A human monoclonal antibody against endotoxin: a randomized, double-blind, placebo-controlled trial. N Engl J Med 1991, 324: 429-36.

Ziegler EJ. Protective antibody to endotoxin core

the emperor’s new clothes? J Infect 1988; 158: 286-90. 3. Fomsgaard A, Baek L, Fomsgaard JS, Engquist A. Preliminary study on treatment of septic shock patients with antilipolysaccharide IgG from blood donors. ScandJ Infect Dis 1989; 21: 697-708. 4. Van Deventer SJH, Buller HR, Ten Cate JW, Sturk A, Pauw W. Endotoxaemia an early predictor of septicaemia in febnle patients. Lancet 1988; ii: 605-09. 5. Calandra T, Glauser MP, Schellekens J, Verhoef J, Swiss-Dutch J5 Immunoglobulin Study Group. Treatment of Gram-negative septic shock with human IgG antibody to Escherichia coli J5: a prospective, double-blind, randomized trial. J Infect Dis 1988; 158: 312-19. 6. Mattsby-Baltzer I, Alving CR. Antibodies to lipid A: occurrence in humans. Rev Infect Dis 1984; 6: 553-57. 7. Stoll BJ, Pollack M, Hooper JA. Antibodies to endotoxin core determinants m normal subjects and in immune globulins for intravenous use. Serodiag Immunother Infect Dis 1987; 1: 21-31. 8. Blok D, van Ogtrop M, Arndt JW, et al. Detection of inflammatory lesions with radiolabelled immunoglobulins. Eur JNucl Med 1990; 16: 303-05. 9. Buscombe JR, Lui D, Ensing G, de Jong R, Ell PJ. 99mTc-human immunoglobulin (HIG)—first results of a new agent for the localization of infection and inflammation Eur J Nucl Med 1990; 16: 649-55. 2.

Dis

SiR,—The use of an IgM human monoclonal antibody has lately been described1 for the treatment of gram-negative shock. In your March 9 editorial you state that this antibody binds to endotoxin. As has been pointed out neutralisation of endotoxin by antibodies is hypotheticalNot all patients having a gram-negative infection have benefited from this treatment. Dr Lehner and Dr Cohen (April 27, p 1036) suggest that failure of monoclonal therapy could result from lack of endotoxaemia. However, we are still faced with difficulties. From earlier studies we know that during gramnegative shock endotoxin concentrations are about 100 pg/ml.3,4 On the assumption of a molecular weight of 10 000 Da for endotoxin this would result in a molar concentration of 10’"mol/1, from which we deduce that endotoxin is probably in a monomeric form. The antibodies given to septic-shock patients can reach at the most a concentration of about 2 x 10-’mol/1, on the basis of a single dose of 100 mg, a distribution volume of 5 1, and a molecular weight of 90 000 Da for one binding site. IgM molecules-as is the human monoclonal antibody used for the treatment of septic shock-are not known for their high affinity. If the antibody had to bind most of the endotoxin it would have an unreal high affinity on the basis of the postulated molar concentrations. Therefore, only a small amount of endotoxin would be bound by the antibody. During septic shock both substances were detected in blood in a free form at the same time,3 indicating that immune complex formation is far from complete. The beneficial effect of this monoclonal antibody is therefore probably not based on the formation of endotoxinantibody complex but could be the result of another mechanism. Another feature of the use of antibody-mediated treatment in gram-negative shock is that only IgM shows a beneficial effect.1,s This finding would not be expected if the antibody had to neutralise monomeric endotoxin; on the contrary, IgG (believed to have higher affinities than IgM) would be the better choice to neutralise such low concentrations of endotoxin. Antibodies to lipid A of both IgM and IgG class are seen in healthy subjects and patients with septic shock.6,7 Their concentration is of the same magnitude3as the concentration of the administered antibody. Even after immunisation with mutant bacteria the immune response was not protective.s Why does immunoglobulin not protect the patient but monoclonal antibody does? A clue comes from studies in which polyclonal immunoglobulins were tagged with 9"Tc. Such labelled

Dietary effects on breast cancer SIR,-Professor Lee and colleagues (May 18, p 1197) show a significant effect of dietary red meat intake, no effect of fat, and a protective effect of soya protein on risk of breast cancer in young women in Singapore. They do not ascribe the red-meat effect to fat in the meat, and offer no alternative explanation. Red meat contains the most readily absorbed form of dietary iron,l and there is evidence that increased body iron stores raise cancer riskperhaps by one or both of two possible mechanisms: (1) boosting the availability of an essential nutrient for cancer cells,3and (2) increasing the production of oxygen radicals.4 In addition, there is some evidence from studies in animals for a role for iron in mammary-tumour induction. Thompson et als administered 1methyl-1-nitrosourea to groups of rats receiving normal rat chow, a low-iron diet, or an iron-supplemented diet. The group receiving dietary iron supplementation had the greatest mammary-tumour burden, whereas that receiving an iron-restricted diet had fewer tumours than the group on the normal diet (although this latter effect may have resulted merely from reduced body weight in the rats on an iron-restricted diet). The protective effect of soya protein seen by Lee et al may also be related to iron metabolism. Soy beans are a source of phytate, a constituent of most cereals, nuts, and legumes, that avidly binds iron in such a way that it is incapable of catalysing the production of oxygen radicals.6 The protective effect

187

of soya protein may be shared by increased intakes of other plant products that are high in phytate but either not consumed in quantity in Singapore or not assessed in the questionnaire Lee et al administer. Supported by the

US Department of Energy under contract DE-AC06-76RLO

1830

Pacific Northwest Laboratory, Richland, WA 99352, USA

RICHARD G. STEVENS

1. Cook JD. Adaptation in iron metabolism Am J Clin Nutr 1990; 51: 301-08. 2. Stevens RG, Jones DY, Micozzi MS, Taylor PR. Body iron stores and the nsk of cancer. N Engl J Med 1988; 319: 1047-52. 3. Weinberg ED. Iron withholding: a defense against infection and neoplasia. Physiol Rev 1984; 64: 65-102. 4 Halliwell B, Gutteridge JMC. Oxygen free radicals and iron in relation to biology and medicine: some problems and concepts. Arch Biochem Biophys 1986; 246: 501-14. 5. Thompson HJ, Kennedy K, Witt M, Juzefyk J. Effect of dietary iron deficiency or excess on the induction of mammary carcinogenesis by 1-methyl-1-nitrosourea. Carcinogenesis 1991; 12: 111-14. 6. Graf E, Eaton JW. Antioxidant functions of phytic acid. Free Radicals Biol Med 1990; 8: 61-69.

How good is HIV envelope glycoprotein vaccine as a T-lymphocyte stimulant? SIR,-Dr Cooney and colleagues’ results (March 9, p 567) show several important gaps that conceal a difficulty with the assessment of T-cell responses to vaccinated antigens. Although they identify a proliferative response post vaccination (table m), they do not present results of the assay with recombinant peptide on their patients’ lymphocytes before vaccination. Our experience with HIV protein and peptides,l and that of others with malarial antigen,2 is that healthy unprimed individuals frequently respond to many proteins or peptides in proliferative assays. Such responses are thought to be crossreactive responses by T cells primed to other antigens ("memory" cells), and are observed only in a small number of cells in any individualCooney et al do not describe the frequency of T cells responding to the peptide post vaccination, or the titration of the responses observed. These three measures should represent important considerations in the estimation of the efficacy of T-cell stimulation by a gp 160 vaccinia construct vaccine. ICRF Human Tumour

Immunology Group,

University College and Middlesex Schools of Medicine, London W1P 8BT, UK

C. MICHIE A. VYAKARNAM P. C. L. BEVERLEY

Matear P, Michie C, Beverley PCL. The proliferative response to HIV-1 gag p24 peptides is not strictly disease related. Int Immunol (in press). 2. Jones KR, Hickling JK, Targett GA, Playfair JH. Polyclonal in vitro proliferative responses from nonimmune donors to plasmodium falciparum malaria antigens require UCHL1 + (memory) T cells. Eur J Immunol 1990; 20: 307-15. 3. Michie C, Vyakarnam A, Beverley PCL. T cell responses to HIV-1 gag p24 peptides. (British Society for Immunology, Epitope Workshop, Charing Cross Hospital, 1.

Vyakarnam A,

April, 1991.)

*** This letter has been shown to Prof Corey and Dr Cooney, whose reply follows.-ED. L. SiR,—Dr Michie and colleagues are rightly concerned that the lymphoproliferative responses to gp160 that we observed post vaccination might represent non-specific proliferation to baculovirus proteins or other non-HIV antigens retained in the envelope preparation after protein purification. Although responses to this antigen were not assessed before vaccination several factors support the specificity of the responses seen post vaccination for HIV epitopes. First, 4 of the 5 individuals who responded to the baculovirus gp160 preparation (table in) also responded after vaccination to one or more additional HIV immunogens. One of the antigens, live LAV, has not elicited any non-specific responses in over a dozen

evaluations of responses sequentially, only recombinant virus recipients showed a response to psoraten/UV-inactivated virus on more than one occasion. These findings, together with the striking anamnestic responses to HIV seen after subsequent boosting of these recombinant vaccine recipients with soluble envelope protein given one year later,’ support the immunogenicity of this vaccinia gpl60 recombinant in vaccinia-primed as well as naive hosts. Division of Virology, University of Washington,

1.

Cooney EL, Corey L, Hu SL, et al. Enhanced immunogenicity in humans of an HIV subunit vaccine regimen employing priming with a vaccinia gp160 recombinant virus (vac/env) by boosting with recombinant HIV envelope glycoprotein (rgp160). (Presented at the Third Annual Meeting of the National Cooperative Vaccine Development Group for AIDS, San Francisco, October 1-5, 1990.)

Bleeding time SIR,-A rigorous scientific reappraisal of the bleeding-time test (June 15 editorial) is long overdue. The general belief that an aspirin a day keeps the doctor away and the more rational use of aspirin in obstetric’"* and cardiological practice presents not only the surgeon and haematologist but also the anaesthetist3 with a dilemma. Extradural anaesthesia is an effective method of pain relief during labour and is commonly used in the intrapartum management of the patient with pre-eclampsia. However, a bleeding diathesis is a contraindication to epidural anaesthesia so the anaesthetist has to do a risk-benefit analysis before offering an epidural anaesthetic to a patient with pre-eclampsia. For that he needs a specific, sensitive, cheap, and rapid bedside test to indicate whether the patient is at increased risk of an epidural haematoma. The bleeding-time test is the only one in current use but, as Rodgers and Levin point out,’ it is a poor predictor of clinically significant bleeding. Values ranging from 105 to 156minutes have been suggested as a cutoff in deciding whether an epidural anaesthetic would be safe but they have not been based on prospective clinical trials. Platelet aggregation studies take several hours, are expensive, and are only available in larger centres-and if aggregation is abnormal does this mean that the risk of bleeding is increased? Thromboelastography has not been evaluated as a predictor of bleeding in the patient taking regular aspirin. The time is right not only for a second look at the bleeding time test, but also for a concerted effort to fmd an adequate test of platelet function, so that obstetric anaesthetists can continue to offer epidural anaesthesia to patients with pre-eclampsia and still sleep soundly at night. M. H. CROSS

Department of Anaesthetics, Edgware General Hospital,

E. J. HAXBY

Middlesex HAS OAD, UK

P. N. ROBINSON

1. Uzal S, Beaufils M, Breert G, Bazm B, Capitant C, Paris J. Prevention of fetal growth retardation with low-dose aspirin: findings of the EPREDA trial. Lancet 1991; 337: 1427-31 2. Schiff E, Peleg E, Goldenberg M, Rosenthal T, Ruppin E. The use of aspirin to prevent pregnancy induced hypertension and lower the ratio of thromboxane A2 to prostacyclin in relatively high risk pregnancies. N Engl J Med 1989; 321: 351-56. 3. Editorial. Aspirin and extradural blocks. Br J Anaesthesia 1991; 66: 1-3. 4. Rodgers RPC, Levin J. A critical review of the bleeding time. Semin Thromb Hemostas

1990; 16: 1-20. 5. Laros K.

Coagulation disorders and haemoglobinopathies in the obstetric and surgical

In: Schnider SM, Levinson G, eds. Anaesthesia for obstetrics, 2nd ed. Baltimore: Williams & Wilkins, 1987: 263-73. 6. O’Sullivan G. Regional anaesthesia and aspirin. Anesthesiology 1990; 73: 359.

patient.

Stopping hiccoughs

uninfected individuals whom we have evaluated so far.

The other antigen preparation, psoraIen/UV-inactivated LAV, was available for use in assays throughout the study period and only 1 (6%) of 18 recombinant virus recipients responded to this immunogen before vaccination. Additionally, of 139 assays run on the 17 vaccinia controls in only 9 (6 % ) was a response to this antigen seen. In each instance the response was low, with a mean stimulation index of 6, compared with 20 among recombinant virus recipients who had a response to this immunogen. Moreover, in

LAWRENCE COREY ELIZABETH COONEY

Seattle, WA 98144, USA

SiR,-During a long period of retirement from clinical practice, I have made an observation which may be of interest. In the absence of patients my family and friends have been the subjects of experiment. An attack of hiccoughs may be socially embarrassing, and in a severely ill patient persistent hiccoughs can sometimes be distressing. The repeated spasms can be brought to a halt by pressing a finger firmly into each external auditory meatus for