I Davies AH,Clark JDA, Dalton KJ, Edwards OM. Insulin requirements of diabetic women who breast feed. Br Med 7. 1989;298: 1357-8. (20 May.) 2 Illingworth PJ ...
hydrate depletion on insulin requirements are therefore small and would be offset by the increased fat intake seen during lactation. Thus the increased insulin sensitivity associated with lactation seems to arise despite the prevailing metabolic conditions. Further, evidence from other species suggests that this has a specific physiological role in maintaining successful lactation.' The lower circulating insulin concentration seen during normal lactation leads to a reduction in lipoprotein uptake and increased mobilisation of lipid stores from peripheral adipose tissue. In contrast, the lactating mammary gland shows an increase in insulin receptors and hence an increase in lipoprotein uptake and utilisation.4 The net result of these processes is an increased availability of lipid substrates for use by the lactating mammary gland. In addition to these effects, the lower insulin concentrations may have a role in reducing non-lactational energy expenditure seen in women breast feeding.2 The increase in insulin sensitivity observed during lactation, which is reversible on weaning, thus seems to be a physiological adaptation of vital importance for maintaining milk production. PETER ILLINGWORTH
Department of Obstetrics and Gynaecology, University of Edinburgh, Edinburgh EH3 9EW PETER W HOWIE
Department of Obstetrics and Gynaecology, University of Dundee, Dundee DD 1 9SY R T JUNG
Ninewells Hospital, Dundee DDI 9SY I Davies AH, Clark JDA, Dalton KJ, Edwards OM. Insulin requirements of diabetic women who breast feed. Br Med 7
widely and change suddenly within much smaller geographical boundaries. There is even some evidence that adaptation to long term unemployment may be more successful in communities in which unemployment is less exceptional.6 Aside from these criticisms of method and interpretation, the findings of Mr Yuen and Dr Balarajan are consistent with other evidence now available. They reinforce our view that the increased workload in general practice that is directly attributable to unemployment should be measured more certainly. This does not now remain an academic nicety if family doctors are to be allocated financial budgets since, as the authors stated, "prevention is not in the hands of the practitioners themselves." Once again the need for a purpose designed, prospective study of morbidity associated with unemployment is self evident. The precedent for primary care, multipractice research is well established in Britain and its value in different contexts unsurpassed. A suitable research project on redundancy and health should include the following features as a minimum: (a) a longitudinal design on identified subjects; (b) collection of prospective data on employees, immediate relatives, and family units recruited through general practitioners; (c) comparison of sequential phases of secure employment, insecure employment, unemployment, and re-employment; and (d) use of primary and secondary health care services as the initial outcome measure with extension to a classification of morbidity. How disappointing that after a decade of high unemployment we remain at the stage of debating research protocols when we might be better informed and therefore more able to manage the consequences. NORMAN BEALE SUSAN NETHERCOTT
1989;298: 1357-8. (20 May.) 2 Illingworth PJ, lung RT, Howie PW, Leslie P, Isles TE. Diminution in energy expenditure during lactation. Br MedJ3
1986;292:437-41. 3 Williamson DH. Integration of metabolism in tissues of the lactating rat. FEBS Lett 1980;117:K93-105. 4 Flint DJ. Role of insulin receptors in nutrient partitioning between mammary gland and adipose tissue. Biochem Soc Trans 1985;13:828-9.
Unemployment and patterns of consultation with the general practitioner SIR,-The findings reported by Mr P Yuen and Dr R Balarajan,' as has so often been the case in this subject, arise from opportunistic use of data collected for other purposes. Mr Yuen and Dr Balarajan are restricted by the obvious limitations of their large database, and their findings may, therefore, be flawed. The research we performed in Calne2 was certainly parochial but not observational; it was a controlled, longitudinal family study, which showed repeatedly the importance of the threat of job loss on the use of health services.2 Although Mr Yuen and Dr Balarajan seem to be aware of this, they were forced to overlook this possible influence; they were obliged to assume that the employed responders to the general household surveys are a homogeneous group with respect to job security, and the difference in morbidity between employed and unemployed men is likely to be underestimated as a result. The nature of the respondents' unemployment is not known sufficiently precisely: the consequences of enforced redundancy are likely to be more traumatic than those of voluntary resignation or of dismissal on the grounds of poor job performance or criminal action, and lack of information may have resulted in further underestimation. Trying to differentiate the degree of effect by using aggregated regional unemployment rates may also be invalid. The immediate job prospects in local "travel to work" areas are probably more relevant. These may vary
1644
Caine, Wiltshire SN 11 8NQ
I Yuen P, Balarajan R. Unemployment and patterns of consultation with the general practitioner. Br MedJ7 1989;298:1212-4. (6 May.) 2 Beale N, Nethercott S. Job-loss and family morbidity: a study of a factory closure..7 R Coll Gen Pract 1985;35:510-4. 3 Beale N, Nethercott S. Job-loss and health-the influence of age and previous morbidity.J R Coll Gen Pract 1986;36:261-4. 4 Beale N, Nethercott S. Job-loss and morbidity: the influence of job-tenure and previous work history. J R Coll Gen Pract
ficing their careers. Denial of this problem results in a profligate waste of investment, more stress related problems among doctors, and declining morale. As a female lecturer who takes a great interest in research, I am distressed that such anachronistic views still hold weight at consultant committees and have been endorsed through publication by the BMJ. L M LOVETT
University Department of Psychiatry, Royal Liverpool Hospital, Liverpool L69 3BX 1 Petch MC. How to appoint a colleague. Br Med J7 1989;298: 1365-7. (20 May.)
Availability of computed tomography SIR,-The paper by Dr R Langton Hewer and Ms V A Wood on the availability of computed tomography in the United Kingdom presents data that were collected two years ago and does not reflect the current provision of these services in the Oxford region.' Only two of our districts do not yet possess computed tomography facilities of their own, and there are now a total of seven installations in the region, five of which have been funded from charitable sources. If there were no other changes in the data presented the Oxford region would now appear third in the list rather than second from the bottom. We agree that there is an overriding case for providing facilities for computed tomography in every large district general hospital. This case may not best be served, however, if it is based on out of date information. S I GOLDING A J MOLYNEUX
Radcliffe Infirmary, Oxford OX2 6HE 1 Hewer RL, Wood VA. Availability of computed tomography of the brain in the United Kingdom. BrMedJ 1989;298:1219-20.
(6 May.)
1986;36:560-3. 5 Beale N, Nethercott S. The nature of unemployment morbidity. 2. Description. J R Coll Gen Pract 1988;38:200-2. 6 Jackson 1', Warr P. Mental health of unemployed men in different parts of England and Wales. BrMedj 1987;295:525.
How to appoint a coileague SIR,-Dr M C Petch seems to take the view that going "home at 6 00 pm to help put the children to bed instead of pursuing laboratory research" is a reason for not appointing a candidate to a consultant post.' He takes care, I note, not to identify the gender of this "helper" candidate. Whether the candidate be a man or woman, the statement reveals a disapprobation for the kind of doctor who believes in a life outside his or her profession. I would suggest that such a person is more likely to be a balanced individual who understands the problems of his or her patients and takes a more holistic professional view. For these reasons he or she may be better able to communicate effectively with patients and influence students and younger doctors to consider wider issues other than research. I am also disturbed by the implication that caring for your own family does not fit in with an ambitious career life. As half of the medical school intake is women, such views must change. It is about time that the medical profession changed its career structure to a more flexible one in which men as well as women can have a reasonable domestic life without grave concerns about sacri-
Mitochondrial myopathies SIR,-Mitochondrial myopathy is excellently described by Dr A H V Schapira in your recent editorial,' and this will do much to raise the index of suspicion for detection of this constellation of diseases. Not mentioned, however, is the fact that diagnosis and treatment have been accelerated by the application of the non-invasive technique of nuclear magnetic resonance with phosphorus-31.2 For the examination the patient lies on a couch within the bore of the magnet with a radioantenna applied to the skin overlying the muscles of the forearm or calf and undertakes light exercise. This method cannot replace the more extensive biochemical and genetic analysis outlined by Dr Schapira, but it may confirm an existing diagnosis,3 avoid duplication of detailed analysis in an affected sibling,4 and permit the early assessment of a response to treatment.5 Although the examination with "P nuclear magnetic resonance is not universally available to neurologists, at least six centres in the United Kingdom-in Oxford, Liverpool, and Cambridge and at Guy's Hospital, the Hospital for Sick Children, and Royal Marsden Hospital in London -have the expensive high field nuclear magnetic resonance equipment required for successful noninvasive diagnosis and monitoring ofmitochondrial diseases, including myopathies. Together, these resources should be more than sufficient to make "P magnetic resonance spectroscopy an attractive and practical addition to
BMJ VOLUME 298
17 JUNE 1989
