1365 TETRAPLOID FIBROBLASTS AND FAMILIAL POLYPOSIS COLI
SIR,-Autosomal dominant familial polyposis coli (FPC) is characterised by multiple adenomatous colonic polyps which become malignant. Patients with the Gardner’s syndrome variant of FPC show benign extracolonic growths in addition to colonic polyps. Shannon Danes’ et al. claimed’ that tetraploidy in cultured skin fibroblasts is increased in Gardner’s syndrome but not familial polyposis without extracolonic lesions. Subsequently this group did observe variation in the percentage of tetraploid skin fibroblasts in both familial polyposis and Gardner’s syndrome and suggested that this was due to genetic heterogeneity.2 We would like to make a preliminary report of our findings in thirteen polyposis patients, twelve of whom are on the register of St Mark’s Hospital. Fibroblasts were cultured by standard methods from skin samples, 3 mm square, normally taken from the inner surface of the forearm. Several primary cultures were set up, with human or fetal calf serum as medium supplement, but sometimes only one culture produced a viable line of fibroblasts. Chromosome preparations were usually made at second or third passage after 5-7 weeks’ culture. The polyposis patients ranged in age from 13 to 66 years; the controls were ten normal people aged between 11 and 56 years. Clinical information (see footnote) and percentage of tetraploidy in cultured fibroblasts are given in the table. TETRAPLOID FIBROBLASTS IN FPC PATIENTS AND CONTROLS
that a population of tetraploid cells may have been present in vivo. Patients FPC 7 and 9 are brothers, the sons of FPC 12; none of them express increased tetraploidy in cultured fibroblasts. Patients FPC 2 and FPC 11 are also brothers, and are the two patients closest to having the Gardner syndrome phenotype. However, the levels of tetraploidy in their cultured skin fibroblasts are widely different. So far therefore there is no evidence that the observed variation in expression of raised tetraploidy levels in either FPC or Gardner’s syndrome patients is a result of genetic heterogeneity, as opposed to skin sampling or culturing effects. This work is
supported by the
Laboratory, Department of Genetics and Biometry, University College London,
JOY D. A. DELHANTY
London NW1 2HE
MARY B. PRITCHARD
St Mark’s Hospital,
H. J. R. BUSSEY
B. C. MORSON
LOW TAR CIGARETTE SMOKING
SIR,-In the survey of over 18 000 male Civil Servants, Dr
Higenbottam and his colleagues (Feb. 23, p. 409) conclude that the tar yield of cigarettes smoked influences phlegm production but not the degree of airflow obstruction. Closer examination of the data, kindly provided by Prof. G. A. Rose (see table), demonstrates not only that decreased tar yield is associated with an increase in forced expiratory volume but also that this association is similar in magnitude to that between decreased tar yield and decreased phlegm prevalence. MEAN FEV
(ADJUSTED FOR AGE AND HEIGHT) AND % PHLEGM (ADJUSTED FOR AGE) BY NUMBER OF CIGARETTES SMOKED AND TAR LEVEL
*Primary cultures initiated in medium with human serum. Tetraploidy expressed as % of 200 dividing cells per chromosome harvest. In FPC patient 2 only 90 cells were available. All FPC patients had adenomas with cancer (cases 1, 2, 4), epidermoid cysts (cases 10, 11, ? 2), osteoma (case 2), ?fibroma (case 5), and congenital retinal pigmentation (case 8). All except patients 1 and 13 have a family history of polyposis coli. There was considerable variation in levels of tetraploidy in independently established lines from the same patient or control. The higher percentages for each person usually correlate with initiation of the culture in medium supplemented with human serum. Since one control value was as high as 11-3% we would consider that only FPC lines 2, 3, and 4 show increased tetraploidy. Shannon Danes has claimed that the presence of epithelial cells is necessary to demonstrate increased tetraploidy in fibroblasts.2 However, two out of these three cultures (FPC 2 and 4) which showed high tetraploidy had no epithelial outgrowth in the primary culture, hence increased tetraploidy need not be related to the presence of cultured epithelial cells. Our experience to date with sampling cultures at later passage (ten or more), indicates that tetraploidy does increase with passage level in skin fibroblasts from affected controls. The fact that the cell line with the highest tetraploidy (FPC 3) exhibited this as early as passage two suggests not or
1. Shannon Danes B, Krush AJ, Gardner EJ. Is Gardner syndrome a distinct genetic disorder? Lancet 1977; ii: 925. 2. Shannon Danes B, Alm T. In vitro studies on adenomatosis of the colon and rectum. J Med Genet 1979; 16: 417-22.
n=number of men observed, SE=standard error. * Assumed approximate midpoints of 5, 15 and 30 cigarettes per day used in regression analysis. t Assumed approximate midpoints of 20, 25, 30, and 35 mg used in
My conclusions were suggested by the observation that, for both the forced expiratory volume (FEV) and phlegm data, responses in the highest tar group for 1-9 cigarettes a day smokers were similar to those in the lowest tar group for 10-19 a day smokers and that those in the highest tar group for 10-19 a day smokers were similar to those in the lowest tar group for smokers of 20 or more cigarettes a day. This suggested that reducing tar yield by about half (from 33+ mg to 18-23 mg) had a similar effect to reducing daily cigarette consumption by about half (from >20 to 10-19 a day or from 10-19 to 1-9 a day) both for FEV and phlegm. Relative changes in response to smoking were less marked for FEV than for phlegm, but even for FEV weighted
multiple regression analysis produced clusion. The equation obtained
FEV (in litres)=3.463-0.0085C-0.0079T, where C is the number of cigarettes smoked per day and T is their tar yield in mg. The regression coefficients for cigarettes and tar yield were similar in magnitude and both independently highly significant their 95% confidence limits being respectively (p<0001), - 0 0104to-0.0066and-0.0113to-0.0049. While my revised conclusions do not necessarily demonstrate an effect of tar per se on FEV levels, since some other component of cigarette smoke that is correlated with tar may be involved instead, they do not provide any a priori evidence supporting Higenbottam and colleagues’ suggestion that it is the gaseous phase of tobacco smoke rather than the tar that may contain the irritant agents leading to airways obstruction. The beneficial effects of FEV levels seen in this study relate to tar reductions occurring during the 1960s. It will be of interest to study the relationship between FEV and smoke component yields in current cigarette smokers, now that many smokers smoke cigarettes with a substantially lowef tar yield than those smoked at the time the survey was carried out. 25 Cedar Road, Sutton SM2 5DG
P. N. LEE
PREVALENCE OF MITRAL VALVE PROLAPSE IN AN AUSTRALIAN POPULATION
SIR,-Mrs Bonella and her co-workers (April 19, p. 880) describe an increase in crosslinked procollagen in floppy mitral valves removed at surgery and 39% of single-chain procollagen in these valves with none detectable in normal valves. Mitral valve prolapse is common in the general population and these findings raise the question of the significance of this diagnosis. We have assessed 200 volunteers (100 men and 100 women) for mitral valve prolapse by M-mode echocardiography using rigid and accepted criteria for the diagnosis’ with additional criteria to exclude false positives. The volunteers responded to an advertisement in the hospital magazine stating that we wished to establish normal values for our echocardiography laboratory. This yielded a group with a wider age spectrum (mean age ±SD, 38.8±12.1 years; range 18-79) than that reported in previous studies. There were eight subjects with unequivocal late systolic mitral valve prolapse, 4 men and 4 women, giving a prevalence of 4%. In 5 of these 8, systolic clicks and/or late systolic murmurs were present on auscultation or on the phonocardiogram, but in the other 3 mitral-valve prolapse could not be detected clinically or by phonocardiography. There were electrocardiographic abnormalities in 2-T-wave changes in 1 and left axis deviation in the other. 1 had atypical chest pain and 1 breathlessness for which no reason could be identified. None complained of palpitations. A volunteer group may not be representative of the whole population. However, the prevalence we found was remarkably similar to that reported in two of the three major American studies, one in young women2 and the other in young men.3The one other study4 reported a much higher frequency in young women and the possible reasons for this will be discussed elsewhere. In a series of 294 routine necropsies Hill et Brown OR, Silverman JF, Harrison DC. Echocardiographic abnormalities in the mitral valve prolapse syndrome. Circulation 1974; 49: 428-33. 2. Prococci PM, Savran SV, Schreiter SL, Bryson AL. Prevalence of clinical mitral valve prolaspe in 1169 young women. N Engl J Med 1976; 294: 1086-88. 3. Darsee JR, Nickolic JR, Nicoloff NB, Lesser LE. Prevalence of mitral valve prolapse in presumably healthy young men. Circulation 1979; 59: 1.
619-22. 4. Markiewicz lapse in
W, Stoner J, London E, Hunt SA, Popp RL. Mitral valve one
1976; 53: 464-73.
proyoung females. Circulation
al.5 found floppy valves in 5%. Clearly mitral valve prolapse is common in the general population and the frequency is approximately the same in men and women. The complications of mitral valve prolapse, the most common being severe mitral regurgitation, are uncommon, however. For example, only 11% of all single mitral-valve replaceover the past two years in this ments undertaken unit were for floppy mitral valves, and a cardiopulmonary similar incidence has been reported from the U.S.6 and the U.K.’ The disparity between these numbers and a prevalence rate of 4% in the general population is striking. There are two immediate questions. How can individuals with mitral-valve prolapse and a high risk of complications be defined? Barlow and Pocock8 suggest that of people with mitral-valve prolapse those with a Marfan habitus may represent a group at risk of having severe mitral regurgitaion. But there are as yet no data to support this. The other question is whether the myxomatous transformation found in patients with floppy mitral valves and severe mitral regurgitation is a non-specific reaction in a congenitally malformed valve or whether it is an expression of a specific mesodermal abnormality with the mitral valve being the main target organ. The interesting observation of accumulation of procollagen in floppy mitral valves removed at surgery for severe mitral regurgitation reported by Bonella et al. support this possibility but clearly does not settle the matter. of Medicine, Prince Henry Hospital, Little Bay, New South Wales 2036, Australia
ANDREW J. HICKEY DAVID E. L. WILCKEN
AMNION FOR LEG ULCERS
SIR,-Iwas delighted to read the papers by Professor Page Faulk and colleagues (May 31) on the use of human amnion in the treatment of chronic ulceration of the legs. Twenty years ago, whilst a student nurse at Grey’s Hospital, Pietermaritzburg, South Africa, a Guy’s trained physician, the late Dr R. R. McKenzie, used fresh amnion for the treatment of his patients with leg ulceration. It was one of my daily tasks to fetch fresh amnion suspended in saline from the maternity ward. As my training progressed I was permitted to do the dressings. We were instructed to use the amnion as soon as it arrived on the ward. It was applied directly to the wound (which had been cleaned with normal saline), and covered by a non-adherent dressing. The limb was firmly bandaged with crepe bandages and elevated. This was standard practice for all Dr McKenzie’s patients with chronic ulceration of the legs. We never expected the treatment to fail or the supply of amnion to dwindle. In 1967, as a staff nurse on a gynaecological ward at a London teaching hospital, I suggested the same treatment for a patient with a chronic varicose ulcer. My suggestion was greeted with scorn but an adventurous registrar allowed me one chance to prove the efficacy of amnion, provided the consultant was not informed. Within two weeks (to my great relief) the wound granulated well and autografting was not thought necessary. A delighted patient was discharged cured of both her gynaecological and varicose problems. However, I was unable to live down the reputation of rattling bones and having consorted with African witch-doctors. Recently, having returned to nursing after a gap of some 5. Hill
DG, Davies MJ, Braimbridge MV. The natural history and surgical management of the redundant cusp syndrome (floppy mitral valve). J Thoracic Cardiovasc Surg 1974; 67: 519-25. 6. Cooley DA, Gerami S, Hallman GL, Wukarsch DC, Hall RJ. Mitral insufficiency due to myxomatous transformation: "Floppy valve syndrome". 1972; 13: 346-49. 7. McKay R, Yacoub MH. Clinical and pathological findings in patients with "Floppy" valves treated surgically. Circulation 1973; 47/48: suppl. III: 63-73. 8. Barlow JB, Pocock WA. Mitral valve prolapse, the specific billowing mitral leaflet syndrome, or an insignificant non-ejection click. Am Heart J 1979; 97: 277-85.