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ESSENTIAL-FATTY-ACID CONTENT OF HENS' EGGS
225
it may be equally true that the " perpetual continuity of function of any living organism " cannot be ensured, the extension of the span of life of some organisms can be achieved by the simplest of manipulations. Take for example the cabbage. The span of life of this edible biennial can be greatly prolonged when seeding is prevented by control of the environmental temperatures7 By cutting off the flower primordia of Reseda odorata the life of this annual can be extended by several years,8 although it is quite unknown why in monocarpic plants the maturing of fruits leads to death. Numerous other examples of the extension of the life of plants can be cited. More spectacular is the work of Williams 9 and Wigglesforth 10 on the juvenile hormone in insects, where application to the insect of material containing this hormone caused the adult cuticle of Rhodnius and Tenebrio to revert to larval cuticle. This is, although the analogy is not quite exact, as though application of some substance to the bearded adult chin caused the skin to revert to the juvenile beardless condition. In the case of mammals, where the built-in homaeostatic mechanisms are more elaborate, manipulations of the internal milieu are notoriously difficult; but it is only necessary to mention McCay’s 1112 successful extension of the life of the laboratory rat to about twice the maximum age reached by normal controls to show that research into the biology of ageing has not been lacking in achievement. The number of laboratory workers in this field is limited, perhaps for the reason that aged humans rarely, if ever, die from the deteriorations consequent on ageing, but rather from the attendant pathological processes the study of which is more immediately rewarding; perhaps also because among laymen and many medical men, as opposed to zoologists, there is still a feeling that such work is not only futile but lacks status. Surely the correct way to regard gerontological research is that it is an important, although embryonic, part of preventive medicine ? The long survival of McCay’s rats was accompanied by a decreased incidence of chronic disease, particularly pulmonary diseases and tumours. Moreover the retarded rat remains active and appears young and alert whatever its chronological age.’2 It is to be noted that this was not a prolongation of the period of senile decrepitude. McCay succeeded in doing in the laboratory what a currently advertised dog-food is said to do. If it is accepted to be desirable to prolong active life in dogs, it,ought to be meritorious to accomplish the same thing in humans, or at least in some humans, which should include Dr. McClure and the present writer.
It may well be therefore that time and funds devoted basic research in ageing might entrain much sooner a greater relief of suffering than the present piecemeal attack on the individual diseases which beset old people. Lastly I suggest that the next important advance in the biology of ageing will most probably be made at a time when the cytologists are still struggling to elucidate the dynamics of the microsomes, the mitochondria, and the cytoplasmic membranes. JOHN BRAY. London, N.W.1. to
THE NATURE OF ESSENTIAL HYPERTENSION SiR,-Correspondence under this title, if not conclusive, has at least been informative. Perhaps, like your Socratic
dialogues, it too might
be
reprinted. Being diffident,
but
Irish by name, I am reminded of the Irishman who, before entering into what seemed to be an altercation,
considerately inquired
whether it
was a
private
affair
or
6. Miller, J. C. Bull. Cornell agric. Exp. Sta. 1929, 488, 46. 7. Curtis, O. F., Clark, D. G. Introduction to Plant Physiology; p. 623. 8. 9. 10. 11. 12.
London, 1950. Molisch, H. The Longevity of Plants; p. 128. New York, 1938. Williams, C. M. Nature, Lond. 1956, 178, 212. Wigglesworth, V. B. J. Insect Physiol. 1958, 2, 73. McCay, C. M. in Cowdry’s Problems of Ageing (edited by A. I. Lansing). Baltimore, 1952. Comfort, A. Biology of Senescence; p. 448. London, 1956.
open to anyone. The letters of Oct. 5 prompt a
me to make
similar inquiry.
In particular, they raise the question of technique. This can be very important. How important-in another connection-is indicated by Harry Golden’s suggestion that integration would be easy in the Southern States if it were vertical, as by removing seats from buses, eating places, theatres and the like. The fact is that taking a blood-pressure may have ominous overtones; it may place in jeopardy the patient’s ability to do his job, provide for his family, or see his friends. The greater the apparent professional rank of the observer relative to that of the patient, the greater the anxiety. Hence, perhaps the most representative pressures would be those taken by the patients themselves. The next best approximation would be a pressure taken by a technician whose manner and speech correspond roughly to those of the patient. While I believe these opinions can be supported, it seems to me that the problem of technique has been well reviewed at the Princeton Conference on Methodology in Epidemiology of Cardiovascular Diseases.1 The recommendations from this group may not reveal the nature of essential hypertension instantly and to everyone’s satisfaction; but they may diminish the areas of controversy. Department of Clinical Investigation, St. Vincent Charity Hospital, A. C. CORCORAN. Cleveland, Ohio. -
ESSENTIAL-FATTY-ACID CONTENT OF HENS’ EGGS
SIR,-Dr. Coppock and his colleagues (Jan. 14) have reported nothing that causes me to withdraw the statement I made in the television interview to which they refer. This was as follows: There are good and bad chickens. I am in favour of the backyard hen, but I am not so certain about the broiler and the battery-fed hen." I said the same remarks applied to eggs of battery hens and farmyard hens. It has been known for more than twenty years that the E.F.A. content of the egg depends on that of the diet of the hen. The powerful combination of Spillers and B.O.C.M. (Unilever) has shown that battery and free-range birds eating roughly the same amounts of E.F.A. (1-24% and 1-52%) have roughly the same amounts of E.F.A. in their eggs (15-3% and 16-1%). This is what one would expect. The free-range hens I worked with ate (amongst other things) .seeds (high in linoleic acid), greenstuff (60% of the fat of which may be linolenic acid), insects (some of which contain fat of which 60% is linoleic acid), and earthworms (the phospholipids of which are very rich in arachidonic acid). How, I wonder, did Dr. Coppock collect for analysis the natural diet of the farmyard hen ? My preference, on present evidence, for eggs from farmyard rather than battery hens was based on a simple experiment I did in the summer of 1956. I allowed the eggs of each type to be fertilised, hatched the chicks, and found material staining red with Sudan IV in the aortas of the day-old chicks from eggs of battery hens and not in those of free-ranging hens. Some of the chicks of the "
former type were then reared indoors on a commercial meal, and in these when killed the fatty deposits were greater whereas there were none in the chicks of the same origin reared free-ranging. I should like to follow up this
work, given (I hope by your correspondents) a battery, some meal, and a gas-liquid chromatograph, because eggs are a very important item of our dietaries and have come under suspicion, perhaps wrongly, because of their efficiency in raising serum-cholesterol. HUGH SINCLAIR. 1. See
Amer. J. publ. Hlth, Oct. 1960.
it may be equally true that the " perpetual continuity of function of any living organism " cannot be ensured, the extension of the span of life of some organisms can be achieved by the simplest of manipulations. Take for example the cabbage. The span of life of this edible biennial can be greatly prolonged when seeding is prevented by control of the environmental temperatures7 By cutting off the flower primordia of Reseda odorata the life of this annual can be extended by several years,8 although it is quite unknown why in monocarpic plants the maturing of fruits leads to death. Numerous other examples of the extension of the life of plants can be cited. More spectacular is the work of Williams 9 and Wigglesforth 10 on the juvenile hormone in insects, where application to the insect of material containing this hormone caused the adult cuticle of Rhodnius and Tenebrio to revert to larval cuticle. This is, although the analogy is not quite exact, as though application of some substance to the bearded adult chin caused the skin to revert to the juvenile beardless condition. In the case of mammals, where the built-in homaeostatic mechanisms are more elaborate, manipulations of the internal milieu are notoriously difficult; but it is only necessary to mention McCay’s 1112 successful extension of the life of the laboratory rat to about twice the maximum age reached by normal controls to show that research into the biology of ageing has not been lacking in achievement. The number of laboratory workers in this field is limited, perhaps for the reason that aged humans rarely, if ever, die from the deteriorations consequent on ageing, but rather from the attendant pathological processes the study of which is more immediately rewarding; perhaps also because among laymen and many medical men, as opposed to zoologists, there is still a feeling that such work is not only futile but lacks status. Surely the correct way to regard gerontological research is that it is an important, although embryonic, part of preventive medicine ? The long survival of McCay’s rats was accompanied by a decreased incidence of chronic disease, particularly pulmonary diseases and tumours. Moreover the retarded rat remains active and appears young and alert whatever its chronological age.’2 It is to be noted that this was not a prolongation of the period of senile decrepitude. McCay succeeded in doing in the laboratory what a currently advertised dog-food is said to do. If it is accepted to be desirable to prolong active life in dogs, it,ought to be meritorious to accomplish the same thing in humans, or at least in some humans, which should include Dr. McClure and the present writer.
It may well be therefore that time and funds devoted basic research in ageing might entrain much sooner a greater relief of suffering than the present piecemeal attack on the individual diseases which beset old people. Lastly I suggest that the next important advance in the biology of ageing will most probably be made at a time when the cytologists are still struggling to elucidate the dynamics of the microsomes, the mitochondria, and the cytoplasmic membranes. JOHN BRAY. London, N.W.1. to
THE NATURE OF ESSENTIAL HYPERTENSION SiR,-Correspondence under this title, if not conclusive, has at least been informative. Perhaps, like your Socratic
dialogues, it too might
be
reprinted. Being diffident,
but
Irish by name, I am reminded of the Irishman who, before entering into what seemed to be an altercation,
considerately inquired
whether it
was a
private
affair
or
6. Miller, J. C. Bull. Cornell agric. Exp. Sta. 1929, 488, 46. 7. Curtis, O. F., Clark, D. G. Introduction to Plant Physiology; p. 623. 8. 9. 10. 11. 12.
London, 1950. Molisch, H. The Longevity of Plants; p. 128. New York, 1938. Williams, C. M. Nature, Lond. 1956, 178, 212. Wigglesworth, V. B. J. Insect Physiol. 1958, 2, 73. McCay, C. M. in Cowdry’s Problems of Ageing (edited by A. I. Lansing). Baltimore, 1952. Comfort, A. Biology of Senescence; p. 448. London, 1956.
open to anyone. The letters of Oct. 5 prompt a
me to make
similar inquiry.
In particular, they raise the question of technique. This can be very important. How important-in another connection-is indicated by Harry Golden’s suggestion that integration would be easy in the Southern States if it were vertical, as by removing seats from buses, eating places, theatres and the like. The fact is that taking a blood-pressure may have ominous overtones; it may place in jeopardy the patient’s ability to do his job, provide for his family, or see his friends. The greater the apparent professional rank of the observer relative to that of the patient, the greater the anxiety. Hence, perhaps the most representative pressures would be those taken by the patients themselves. The next best approximation would be a pressure taken by a technician whose manner and speech correspond roughly to those of the patient. While I believe these opinions can be supported, it seems to me that the problem of technique has been well reviewed at the Princeton Conference on Methodology in Epidemiology of Cardiovascular Diseases.1 The recommendations from this group may not reveal the nature of essential hypertension instantly and to everyone’s satisfaction; but they may diminish the areas of controversy. Department of Clinical Investigation, St. Vincent Charity Hospital, A. C. CORCORAN. Cleveland, Ohio. -
ESSENTIAL-FATTY-ACID CONTENT OF HENS’ EGGS
SIR,-Dr. Coppock and his colleagues (Jan. 14) have reported nothing that causes me to withdraw the statement I made in the television interview to which they refer. This was as follows: There are good and bad chickens. I am in favour of the backyard hen, but I am not so certain about the broiler and the battery-fed hen." I said the same remarks applied to eggs of battery hens and farmyard hens. It has been known for more than twenty years that the E.F.A. content of the egg depends on that of the diet of the hen. The powerful combination of Spillers and B.O.C.M. (Unilever) has shown that battery and free-range birds eating roughly the same amounts of E.F.A. (1-24% and 1-52%) have roughly the same amounts of E.F.A. in their eggs (15-3% and 16-1%). This is what one would expect. The free-range hens I worked with ate (amongst other things) .seeds (high in linoleic acid), greenstuff (60% of the fat of which may be linolenic acid), insects (some of which contain fat of which 60% is linoleic acid), and earthworms (the phospholipids of which are very rich in arachidonic acid). How, I wonder, did Dr. Coppock collect for analysis the natural diet of the farmyard hen ? My preference, on present evidence, for eggs from farmyard rather than battery hens was based on a simple experiment I did in the summer of 1956. I allowed the eggs of each type to be fertilised, hatched the chicks, and found material staining red with Sudan IV in the aortas of the day-old chicks from eggs of battery hens and not in those of free-ranging hens. Some of the chicks of the "
former type were then reared indoors on a commercial meal, and in these when killed the fatty deposits were greater whereas there were none in the chicks of the same origin reared free-ranging. I should like to follow up this
work, given (I hope by your correspondents) a battery, some meal, and a gas-liquid chromatograph, because eggs are a very important item of our dietaries and have come under suspicion, perhaps wrongly, because of their efficiency in raising serum-cholesterol. HUGH SINCLAIR. 1. See
Amer. J. publ. Hlth, Oct. 1960.