- Email: [email protected]
BIRTH-RATE AND SPONTANEOUS ABORTIONS
1390 understand the role of these peptides it is essential to compare serum levels measured by both immunoassay and bioassay, and to correlate these measured levels with clinical and biological observations. the
R. F. HARVEY LYNDA DOWSETT M. HARTOG A. E. READ.
Department of Medicine, Bristol Royal Infirmary, Bristol BS2 8HW.
magnesium deficiency in the development of arrhythmias, 6-8 and in sudden cardiac deaths,3 as well as the known biological effects of magnesium,9, 10suggest that the balance of magnesium, and possibly also that of other minerals, should be included in programmes studying the aetiological factors of heart-disease. Department of Pharmacology, University of Oulu, SF-90100 Oulu 10.
H. KARPPANEN.
Department of Clinical
Pharmacology,
BIRTH-RATE AND SPONTANEOUS ABORTIONS
SiR.—The birth-rate is declining
present, and demographers are being cautious in interpreting this. It is not clear, they say, whether women are deciding to have fewer children, or whether they are just postponing them. In this context it would be useful to know whether the spontaneous abortion-rate has changed during the past decade. I would welcome any speculation, or preferably data, on this point. Galton Laboratory, Wolfson House, 4 Stephenson Way, London NW1 2HE.
Finland.
P. J. NEUVONEN.
at
WILLIAM H.
JAMES.
ISCHÆMIC HEART-DISEASE AND SOIL MAGNESIUM IN FINLAND SIR,—The high mortality from ischsemic heart-disease in Finland shows a clear-cut regional distribution. In eastern Finland the death-rates are nearly twice those in the south-western parts of the country.1 It has been reported that there is a difference in cardiovascular mortality between towns with soft and hard drinking watery Moreover, a diminished content of heart magnesium has been found after a sudden death from heartdisease.3 In addition, some beneficial effect of magnesium sulphate on arterial diseases, including coronary heartdisease, has been reported.44 The average content of exchangeable magnesium in soil, based on over 30,000 determinations by atomic absorption spectrophotometry in Finland, is over 5300 mg. per I. in the south-western parts of the country.5 The average soil content of magnesium declines gradually towards the east so that less than 100 mg. per 1. is found in the eastern areas with the very high death-rates.1,5 The contents of exchangeable calcium and potassium are also somewhat higher in south-western Finland than in the eastern areas. On the other hand, the regional distribution of soil copper or manganese 5 apparently has no correlation with the incidence of cardiovascular disease. Accordingly, in Finland there is an apparent inverse correlation between the mortality from ischxmic heart-disease and the soil content of calcium and potassium and, in particular, that of magnesium. It can be anticipated that, in the past decades in Finland, the intake of magnesium and possibly some other minerals has been related to the content of these principles in soil, since the people in rural areas have satisfied their caloric needs largely with local agricultural products. Probably the content of minerals in drinking-water is also related to their content in soil. No conclusion, of course, can be drawn about a possible causal relationship between the intake of minerals and heart mortality. However, the possible involvement of
Puska, P. Suom. Lääk. Lehti, 1972, 27, 3071. Stitt, F. W., Clayton, D. G., Crawford, M. D., Morris, J. N. Lancet, 1973, i, 122. 3. Chipperfield, B., Chipperfield, J. R. ibid. 1973, ii, 293. 4. Browne, S. E. Practitioner, 1964, 192, 791. 5. Kurki, M. Suomen peltojen viljavuudesta II. Helsinki, 1972. 1. 2.
University of Helsinki, SF-00290 Helsinki 29,
WATER HARDNESS AND MAGNESIUM IN HEART MUSCLE years ago it
was suggested by Crawford and the of basis Crawford," medicolegal necropsies after accidental death, that young men living in Glasgow, a soft-water area, had lower concentrations of magnesium in their coronary arteries than did young male residents of London, an area with relatively hard water. No such difference could be detected beyond the age of 40, but this was an age by which Glasgow men had significantly more atheroma, with consequent deposition of magnesium, as well as calcium, in the arterial surface. This difficulty in distinguishing characteristics that may reflect special susceptibility to disease from those that reflect the presence of established lesions does not arise when the tissue studied is heart muscle. Two independent studies reported in your columns (Aug. 11, p. 293; Aug. 25, p. 450) have indicated that heart-muscle concentration of magnesium tends to be lower in subjects who have died of myocardial infarction than in those who have died from other causes. The Chipperfields (Aug. 11) concluded their discussion of this finding by suggesting that residents of soft-water areas may have lower magnesium concentrations in heart muscle than do residents of hard-water areas. We are able to confirm that just such a difference has been observed in a Canadian study now nearing completion. Among the subjects in our study were 64 males who had died as the result of accidents, and are therefore of the general presumed to be more nearly representative " population than are victims of natural causes ". 20 of these were residents of 3 different hard-water areas (finished municipal supplies of 342 to 516 p.p.m. total hardness), and 44 were residents of 5 soft-water areas (53 p.p.m. or less). Mean magnesium concentrations in wet heart tissue for the hard and soft water residents were 222-3 Vg. per g. and 206’7 g. per g., respectively. The difference of 15-6 g. per g. is 2-35 times its standard error and can be considered statistically significant at the 0-01 level, since it is in the direction predicted by the prior alternative hypothesis. The subjects from hard-water areas were on average 6 years younger than those from soft-water areas but, given the sign of the weak (non-significant) relationship between age and magnesium level, this age discrepancy could only have biased the study against detection of a difference between the two classes of area. In a fuller report we shall consider the extent to which the apparent depression of magnesium level in residents of soft-water areas is specific to heart muscle (by comparison with pectoral and diaphragmatic muscles, an effect on serum levels having been previously excluded 12), and
SIR,-Some
on
Seller, R. H. Am. Heart J. 1971, 82, 551. Wacker, W. E. C., Parisi, A. F. New Engl. J. Med. 1968, 278, 772. Wüstenberg, P. W. Z. ges. inn. Med. 1972, 27, 45. Alpert, N. R., Gordon, M. S. Am. J. Physiol. 1962, 202, 940. Katz, A. M. Physiol. Rev. 1970, 50, 63. Crawford, T., Crawford, M. D. Lancet, 1967, i, 229. 12. Can. med. Ass. J. 1972, 107, 34. 6. 7. 8. 9. 10. 11.
R. F. HARVEY LYNDA DOWSETT M. HARTOG A. E. READ.
Department of Medicine, Bristol Royal Infirmary, Bristol BS2 8HW.
magnesium deficiency in the development of arrhythmias, 6-8 and in sudden cardiac deaths,3 as well as the known biological effects of magnesium,9, 10suggest that the balance of magnesium, and possibly also that of other minerals, should be included in programmes studying the aetiological factors of heart-disease. Department of Pharmacology, University of Oulu, SF-90100 Oulu 10.
H. KARPPANEN.
Department of Clinical
Pharmacology,
BIRTH-RATE AND SPONTANEOUS ABORTIONS
SiR.—The birth-rate is declining
present, and demographers are being cautious in interpreting this. It is not clear, they say, whether women are deciding to have fewer children, or whether they are just postponing them. In this context it would be useful to know whether the spontaneous abortion-rate has changed during the past decade. I would welcome any speculation, or preferably data, on this point. Galton Laboratory, Wolfson House, 4 Stephenson Way, London NW1 2HE.
Finland.
P. J. NEUVONEN.
at
WILLIAM H.
JAMES.
ISCHÆMIC HEART-DISEASE AND SOIL MAGNESIUM IN FINLAND SIR,—The high mortality from ischsemic heart-disease in Finland shows a clear-cut regional distribution. In eastern Finland the death-rates are nearly twice those in the south-western parts of the country.1 It has been reported that there is a difference in cardiovascular mortality between towns with soft and hard drinking watery Moreover, a diminished content of heart magnesium has been found after a sudden death from heartdisease.3 In addition, some beneficial effect of magnesium sulphate on arterial diseases, including coronary heartdisease, has been reported.44 The average content of exchangeable magnesium in soil, based on over 30,000 determinations by atomic absorption spectrophotometry in Finland, is over 5300 mg. per I. in the south-western parts of the country.5 The average soil content of magnesium declines gradually towards the east so that less than 100 mg. per 1. is found in the eastern areas with the very high death-rates.1,5 The contents of exchangeable calcium and potassium are also somewhat higher in south-western Finland than in the eastern areas. On the other hand, the regional distribution of soil copper or manganese 5 apparently has no correlation with the incidence of cardiovascular disease. Accordingly, in Finland there is an apparent inverse correlation between the mortality from ischxmic heart-disease and the soil content of calcium and potassium and, in particular, that of magnesium. It can be anticipated that, in the past decades in Finland, the intake of magnesium and possibly some other minerals has been related to the content of these principles in soil, since the people in rural areas have satisfied their caloric needs largely with local agricultural products. Probably the content of minerals in drinking-water is also related to their content in soil. No conclusion, of course, can be drawn about a possible causal relationship between the intake of minerals and heart mortality. However, the possible involvement of
Puska, P. Suom. Lääk. Lehti, 1972, 27, 3071. Stitt, F. W., Clayton, D. G., Crawford, M. D., Morris, J. N. Lancet, 1973, i, 122. 3. Chipperfield, B., Chipperfield, J. R. ibid. 1973, ii, 293. 4. Browne, S. E. Practitioner, 1964, 192, 791. 5. Kurki, M. Suomen peltojen viljavuudesta II. Helsinki, 1972. 1. 2.
University of Helsinki, SF-00290 Helsinki 29,
WATER HARDNESS AND MAGNESIUM IN HEART MUSCLE years ago it
was suggested by Crawford and the of basis Crawford," medicolegal necropsies after accidental death, that young men living in Glasgow, a soft-water area, had lower concentrations of magnesium in their coronary arteries than did young male residents of London, an area with relatively hard water. No such difference could be detected beyond the age of 40, but this was an age by which Glasgow men had significantly more atheroma, with consequent deposition of magnesium, as well as calcium, in the arterial surface. This difficulty in distinguishing characteristics that may reflect special susceptibility to disease from those that reflect the presence of established lesions does not arise when the tissue studied is heart muscle. Two independent studies reported in your columns (Aug. 11, p. 293; Aug. 25, p. 450) have indicated that heart-muscle concentration of magnesium tends to be lower in subjects who have died of myocardial infarction than in those who have died from other causes. The Chipperfields (Aug. 11) concluded their discussion of this finding by suggesting that residents of soft-water areas may have lower magnesium concentrations in heart muscle than do residents of hard-water areas. We are able to confirm that just such a difference has been observed in a Canadian study now nearing completion. Among the subjects in our study were 64 males who had died as the result of accidents, and are therefore of the general presumed to be more nearly representative " population than are victims of natural causes ". 20 of these were residents of 3 different hard-water areas (finished municipal supplies of 342 to 516 p.p.m. total hardness), and 44 were residents of 5 soft-water areas (53 p.p.m. or less). Mean magnesium concentrations in wet heart tissue for the hard and soft water residents were 222-3 Vg. per g. and 206’7 g. per g., respectively. The difference of 15-6 g. per g. is 2-35 times its standard error and can be considered statistically significant at the 0-01 level, since it is in the direction predicted by the prior alternative hypothesis. The subjects from hard-water areas were on average 6 years younger than those from soft-water areas but, given the sign of the weak (non-significant) relationship between age and magnesium level, this age discrepancy could only have biased the study against detection of a difference between the two classes of area. In a fuller report we shall consider the extent to which the apparent depression of magnesium level in residents of soft-water areas is specific to heart muscle (by comparison with pectoral and diaphragmatic muscles, an effect on serum levels having been previously excluded 12), and
SIR,-Some
on
Seller, R. H. Am. Heart J. 1971, 82, 551. Wacker, W. E. C., Parisi, A. F. New Engl. J. Med. 1968, 278, 772. Wüstenberg, P. W. Z. ges. inn. Med. 1972, 27, 45. Alpert, N. R., Gordon, M. S. Am. J. Physiol. 1962, 202, 940. Katz, A. M. Physiol. Rev. 1970, 50, 63. Crawford, T., Crawford, M. D. Lancet, 1967, i, 229. 12. Can. med. Ass. J. 1972, 107, 34. 6. 7. 8. 9. 10. 11.