692
pared before drug treatment, after saliuretics for three months, and after an additional nine months of either timolol/thiazide combination (poor responders) or diuretics only (responders). Thus, there seemed to be no reason to anticipate that the additive antihypertensive effect of timolol, when added to diuretic drug therapy, would lower blood-pressure by reducing P.R.A. We, therefore, have extended the data of Chalmers et al., who applied short periods of study (twomonths), by looking at the combined effect of long-term treatment (nine months) with timolol and a diuretic drug in essential hypertension, and we can support their suggestion that the antihypertensive effect of timolol in essential hypertension is independent of changes in diuretic-stimulated P.R.A. Unit of Clinical Physiology, Minerva Institute for Medical P.O. Box 819, 00101 Helsinki 10, Finland
Research,
F. FYHRQUIST K. KURPPA M. KANNAS
COLLAPSE DURING CHANNEL SWIM
SIR,-Long-distance swimming in cold water is accompanied by heat loss,’ and by inhalation and ingestion of sea water, and often vomiting due to this and to seasickness. Although attempts at record-breaking swims are often abandoned only when the swimmer collapses (and a few swimmers have died), there is little information on the precise cause of these accidents. I was asked to examine a 27-year-old man when he collapsed at 10.15 P.M. on Aug. 5 after swimming for 27 h in water of 16°C while attempting to make the first triple crossing of the Channel. He had vomited repeatedly throughout the swim, finally developed severe chest pain, and was pulled from the water. He was examined 90 min later in the open boat that brought him ashore, in which he had been lying covered with blankets since leaving the water. He could answer simple questions but was unable to stand or carry on a conversation. Carotid pulse and auscultation of the heart showed heart-rate to be
irregular, 123/min. Peripheral pulses were not clearly palpable ; arterial pressure 85/45 mm Hg (auscultation). Although sublingual temperature was only 32. 1 °C, ear temperature with servo-control2 was 3 5-1°C rising; this was confirmed by a rectal reading of 35’4°C. Rewarming was then assisted by hot water bottles and he was taken by ambulance to the Kent and Canterbury Hospital and admitted under Dr Prosser’s care, where electrocardiography showed atrial fibrillation with irregular atrioventricular block. This did not revert spontaneously, and the patient was monitored overnight and converted to normal rhythm by D.C. shock the next day. Hypothermia combined with severe physical exercise had probably caused the arrhythmia but a small oesophageal tear due to vomiting, with irritation of the atrium, might have been the precipitating factor. A Channel swimmer probably runs little risk if he or she is prepared to abandon the swim on feeling excessively cold or ill, and if attended by the usual small boat with an experienced However, when swimmers plan to go to the limit of endurance to break records, additional precautions are highly desirable. Competition rules do not allow the swimmer to be touched, but body temperature could probably be monitored satisfactorily by radiotelemetry. A deep body temperature below 34°C and falling or severe prolonged vomiting should call for abandonment of a swim. Facilities for active rewarming are desirable on rescue; a hot bath is often impracticable but even small boats can generally provide bottles filled with water just not hot enough to cause pain to an observer’s hand, as well as blankets. Medical examination by someone familiar with the problem is desirable before the patient is moved. Despite the difficulty in examining a patient in a small boat, and crew.
1. 2.
Pugh, L. G. C., Edholm, O. G. Lancet, 1955, ii, 761. Keatinge, W. R., Sloan, R. E. G. J. appl Physiol. 1975, 38, 919.
often at night, this can detect most conditions requiring immediate transfer to hospital, particularly a fast cardiac arrhythmia such as was present in this case. London Hospital Medical London E 1 2AD
College,
W. R.
KEATINGE
AGGLUTINATION GROUPING OF STREPTOCOCCI
SiR,—The fact that streptococci
are not
grouped serologi-
often as they should be is attributable in part to the time taken to perform the usual precipitation tests and in part to the cost of the reagents. Grouping by the co-agglutination method provides an effective solution to the first of these difficulties. Kits for co-agglutination grouping of streptococci are now on the market (’Phadebact’, Pharmacia), and work well. In 1956, Rosendal’ described a method of grouping by the slide agglutination of trypsinised streptococcal suspensions, and this is still widely used in Scandinavia. The co-agglutination methodmakes use of a suspension of Staphylococcus aureus that is rich in protein A to which the group antibody is non-specifically adsorbed. When mixed with a trypsinised suspension of a streptococcus of homologous group, instant heavy flocculation appears. A separate staphylococcal suspension has to be prepared for the detection of each streptococcal group, and the shelf-life of the suspensions is limited. We have re-examined the conventional agglutination and the co-agglutination methods of grouping streptococci. Unfortunately, commercially produced grouping sera intended for use in the precipitation test give unwanted cross-reactions when used for either of the agglutination-grouping methods. These cross-reactions were easily removed by absorption of the sera with heat-killed suspensions of heterologous group, but a fairly extensive programme of testing was necessary to determine which absorbing suspensions to use for the treatment of any particular set of antisera. After the appropriate absorptions, commercially available batches of grouping sera gave good results in tests by either agglutination method. Any technician familiar with enterobacterial slide-agglutination reactions would have no difficulty in recognising a positive result in the conventional slide-agglutination method, but an occasional group-A streptococcus (less than 1%) and a few group-B streptococci gave negative results. By the co-agglutination method, positive reactions appeared immediately and were unmistakable, and no false-negative results were obtained. Agglutination grouping, by either that most commercial method, has the enormous can be even after used at high dilutions, antisera, absorption, thus giving considerable economy. In the course of the experiments, however, it became obvious that it was not necessary to use separate staphylococcal suspensions to which each of the group antibodies had been adsorbed; and antiserum and the staphylococcal suspension could be added separately (and in either order) to the trypsinised suspension of streptococci or to streptococci that had been grown in the presence of trypsin, and co-agglutination occurred instantly. It is customary to use the staphylococcal strain Cowan I (no. NCTC8530) for co-agglutination tests, but we found that 6 of 12 randomly chosen strains of Staph. aureus acted equally well. Staphylococci grown in broth or on agar and washed once in physiological saline solution were suitable. The small-scale production of antisera for agglutination grouping by clinical microbiology laboratories would be a serious burden. If, however, commercial manufacturers provided such sera, the microbiologist could choose between the conventional agglutination test (and add the staphylococcal suspension only if an unexpected negative reaction was
cally
as
adyantage
1. 2.
Rosendal, K. Acta path. microbiol. scand. 1956, 39, 127. Christensen, P., Kahlmeter, G., Jonsson, S., Kronvall, 1973,7, 881.
G.
Infect. Immun
693 inconsistent, and these studies
were abandoned, overby the description of the hepatitis B antigens and, more recently, by animal and immunoelectronmicroscopic observations pertinent to hepatitis A.
obtained) and our modified co-agglutination test for every test.
were
In neither case would he be using reagents with a short shelflife, Workers who use the co-agglutination method to detect other antigen-antibody reactions may also find that the separate addition of antiserum and staphylococcal strain saves them
shadowed
considerable labour. Cross-Infection Reference Laboratory, Ceniral Public Health Laboratory, London NW9 5HT
W. R. MAXTED ANDROULLA EFSTRATIOU M. T. PARKER
SIR,-In bronchial asthma, exercise-induced symptoms can be a disabling and socially restricting feature of the disease.I At a clinic visit a 38-year-old male patient whose main complaint was of wheezing induced by running, also volunteered that he developed similar symptoms during sexual intercourse. The asthmatic features often interfered with the satisfactory completion of coitus and were causing considerable strain on his marital relationship. After this, three further male patients aged 25-40, with exercise-induced asthma, were asked specifically about the possible onset of symptoms during intercourse. All these patients, surprisingly, admitted to considerable sexual difficulties because of the onset of their typical symptoms of wheezing and dyspnrea. None had been asked previously about this feature of their condition, nor had they wished to mention this aspect because of embarrassment. After prophylactic therapy had been started (two with disodium cromoglycate, two with a steroid aerosol), all had a general improvement in their asthma. Two indicated that while on therapy their sexually induced asthmatic symptoms were eliminated, and in the two others the difficulties were considerably modified. The mechanism of this reaction is unlikely to be different from that of asthma initiated by other forms of exercise such as running or cycling. Anxiety and emotional factors may have played a part, but in this group with exercise-induced features predominating, these factors are unlikely to be significant. It is conceivable, however, that sexual activity in bed, by disturbing the surrounding house-dust mite population may provide an allergen challenge in sensitised individuals. It is only through increased awareness and specific questioning that the frequency of angina pectoris occurring during intercourse in patients with coronary heart-disease has been demonstrated.2 "Sexercise" induced asthma may also be common but overlooked both by the family doctor and the respiratory physician. The successful outcome in this group of patients serves to demonstrate the need for a direct approach in those at risk. IAN S. SYMINGTON
JAMES W. KERR
INHIBITION OF PHYTOHÆMAGGLUTININ TRANSFORMATION BY SERUM OF PATIENTS WITH FULMINANT HEPATITIS
Sn,—Dr Dupuy and his colleagues (Sept. 11,
they
were
It may be that inhibition of P.H.A transformation is associated with hepatitis B (4/6 of Dupuy’s cases were known to be associated with hepatitis B) and that the inconsistency encountered in earlier studies was related to our inability properly to identify octiologically distinct varieties of hepatitis. Virus Laboratory, Department of Microbiology, Institute of Child Health, London WC1N 1EH
SEXERCISE-INDUCED ASTHMA
Department of Respiratory Medicine, Western Infirmary and Knightswood Hospital, Glasgow
as
p.
578)
describe the inhibition of phytohasmagglutinin transformation
oy serum of patients with fulminant viral hepatitis. This was ?1 described by Mella and myself in 1967and 1968.4 Subsequently several attempts were made by my laboratory by others to investigate this finding further. The results 1 McNeill, R S., Nairn, J. R., Millar, J. S., Nairn, C. G. Q. Jl Med. 1966,
137, 55 2 Hellerstein, H. K., Fnedman, E. H. Archs intern. Med. 1970, 125, 987. 3 Mell a. B, Lang, D. J. Science, 1967, 155, 80. 4 Mella B, Lang, D. J. Ann N.Y. Acad Sci 1968, 155, 880.
DAVID J. LANG
BREAST IS BEST FOR CORONARY PROTECTION
SiR,—Your contributor (Aug. 21, p. 412) has a hunch that "breast is best", but admits his reasons are largely related to the emotional and behavioural bonding of mother and baby. But he overlooks a wealth of circumstantial evidence which points to coronary protection being a likely benefit of breast
feeding. Non-lipid-containing histological changes in the coronary arteries of infants and young children which are almost certainly predisposing to later atherosclerosis have been described by many pathologists, 1-3 notably Osborn.4These changes have been found in children who have died from gastroenteritis, other infections, or any condition associated with dehydration and collapse, and also in those killed accidentally in whom there was no obvious preceding disease. With a variety of associations, but no proof of causation, they must be referred to as non-specific. Often no doubt, and usually in lowrisk countries in which atherosclerosis and its complications are rare, injury is followed by repair. However, given a later unfavourable nutritional environment in the form of a modern Western-type diet, it is probable that the increased permeability of the arterial wall and changes which predispose to the infiltration, retention, and accumulation of low-density lipoproteins predispose to atherosclerosis. Osborn described the pathological changes in 1500 young people aged 0-20 years. Since serial observations in an individual are impossible, conclusions had to be based on the spectrum of pathological changes from the accumulation of mucopolysaccharides to fully developed atherosclerotic plaques. In infants with no history of relevant preceding disease, causes are likely to be nutritional. He closely questioned more than 100 mothers and concluded that the lesions described were more frequent and severe in the predominantly bottlefed and uncommon or mild in those predominantly breast-fed. Clearly only a prospective study can be conclusive. It is therefore reasonable to consider the differences between human and cow’s milk and the likelihood of their being responsible for the early changes in the coronary arteries. Breast milk has evolved as a perfect and all-sufficient food for the first twelve months of life or longer while cow’s milk has evolved for very different needs. The only similarities in the two varieties lie in the water and, perhaps, the sugar. Total protein in cow’s milk is much higher and its constituent aminoacid pattern is very different. Antibodies are present in the blood of many infants and this immunological response could itself damage the arterial wall and also increase platelet adhesiveness and aggregation which can have harmful effects.6 Cow’s milk is grossly deficient in essential fatty acids. They amount to only 25% of the concentration in human milk in 1. Moon, H. D. Circulation, 1957, 16, 268. 2. Daoud, A. et al. Exp. mol. Path. 1964, 3, 475. 3. Pesonen, E. Atherosclerosis, 1974, 20, 173. 4. Osborn, G. R. Incubation Period of Coronary
Thrombosis; p. 177. London,
1963. 5. Osborne, G. R. Colloq. int. C.N.R.S. 1967, no. 169. 6. Davies, D. F. Am. Heart J. 1971, 81, 289. 7. György, P. Am. J. clin. Nutr. 1971, 24, 970.
pared before drug treatment, after saliuretics for three months, and after an additional nine months of either timolol/thiazide combination (poor responders) or diuretics only (responders). Thus, there seemed to be no reason to anticipate that the additive antihypertensive effect of timolol, when added to diuretic drug therapy, would lower blood-pressure by reducing P.R.A. We, therefore, have extended the data of Chalmers et al., who applied short periods of study (twomonths), by looking at the combined effect of long-term treatment (nine months) with timolol and a diuretic drug in essential hypertension, and we can support their suggestion that the antihypertensive effect of timolol in essential hypertension is independent of changes in diuretic-stimulated P.R.A. Unit of Clinical Physiology, Minerva Institute for Medical P.O. Box 819, 00101 Helsinki 10, Finland
Research,
F. FYHRQUIST K. KURPPA M. KANNAS
COLLAPSE DURING CHANNEL SWIM
SIR,-Long-distance swimming in cold water is accompanied by heat loss,’ and by inhalation and ingestion of sea water, and often vomiting due to this and to seasickness. Although attempts at record-breaking swims are often abandoned only when the swimmer collapses (and a few swimmers have died), there is little information on the precise cause of these accidents. I was asked to examine a 27-year-old man when he collapsed at 10.15 P.M. on Aug. 5 after swimming for 27 h in water of 16°C while attempting to make the first triple crossing of the Channel. He had vomited repeatedly throughout the swim, finally developed severe chest pain, and was pulled from the water. He was examined 90 min later in the open boat that brought him ashore, in which he had been lying covered with blankets since leaving the water. He could answer simple questions but was unable to stand or carry on a conversation. Carotid pulse and auscultation of the heart showed heart-rate to be
irregular, 123/min. Peripheral pulses were not clearly palpable ; arterial pressure 85/45 mm Hg (auscultation). Although sublingual temperature was only 32. 1 °C, ear temperature with servo-control2 was 3 5-1°C rising; this was confirmed by a rectal reading of 35’4°C. Rewarming was then assisted by hot water bottles and he was taken by ambulance to the Kent and Canterbury Hospital and admitted under Dr Prosser’s care, where electrocardiography showed atrial fibrillation with irregular atrioventricular block. This did not revert spontaneously, and the patient was monitored overnight and converted to normal rhythm by D.C. shock the next day. Hypothermia combined with severe physical exercise had probably caused the arrhythmia but a small oesophageal tear due to vomiting, with irritation of the atrium, might have been the precipitating factor. A Channel swimmer probably runs little risk if he or she is prepared to abandon the swim on feeling excessively cold or ill, and if attended by the usual small boat with an experienced However, when swimmers plan to go to the limit of endurance to break records, additional precautions are highly desirable. Competition rules do not allow the swimmer to be touched, but body temperature could probably be monitored satisfactorily by radiotelemetry. A deep body temperature below 34°C and falling or severe prolonged vomiting should call for abandonment of a swim. Facilities for active rewarming are desirable on rescue; a hot bath is often impracticable but even small boats can generally provide bottles filled with water just not hot enough to cause pain to an observer’s hand, as well as blankets. Medical examination by someone familiar with the problem is desirable before the patient is moved. Despite the difficulty in examining a patient in a small boat, and crew.
1. 2.
Pugh, L. G. C., Edholm, O. G. Lancet, 1955, ii, 761. Keatinge, W. R., Sloan, R. E. G. J. appl Physiol. 1975, 38, 919.
often at night, this can detect most conditions requiring immediate transfer to hospital, particularly a fast cardiac arrhythmia such as was present in this case. London Hospital Medical London E 1 2AD
College,
W. R.
KEATINGE
AGGLUTINATION GROUPING OF STREPTOCOCCI
SiR,—The fact that streptococci
are not
grouped serologi-
often as they should be is attributable in part to the time taken to perform the usual precipitation tests and in part to the cost of the reagents. Grouping by the co-agglutination method provides an effective solution to the first of these difficulties. Kits for co-agglutination grouping of streptococci are now on the market (’Phadebact’, Pharmacia), and work well. In 1956, Rosendal’ described a method of grouping by the slide agglutination of trypsinised streptococcal suspensions, and this is still widely used in Scandinavia. The co-agglutination methodmakes use of a suspension of Staphylococcus aureus that is rich in protein A to which the group antibody is non-specifically adsorbed. When mixed with a trypsinised suspension of a streptococcus of homologous group, instant heavy flocculation appears. A separate staphylococcal suspension has to be prepared for the detection of each streptococcal group, and the shelf-life of the suspensions is limited. We have re-examined the conventional agglutination and the co-agglutination methods of grouping streptococci. Unfortunately, commercially produced grouping sera intended for use in the precipitation test give unwanted cross-reactions when used for either of the agglutination-grouping methods. These cross-reactions were easily removed by absorption of the sera with heat-killed suspensions of heterologous group, but a fairly extensive programme of testing was necessary to determine which absorbing suspensions to use for the treatment of any particular set of antisera. After the appropriate absorptions, commercially available batches of grouping sera gave good results in tests by either agglutination method. Any technician familiar with enterobacterial slide-agglutination reactions would have no difficulty in recognising a positive result in the conventional slide-agglutination method, but an occasional group-A streptococcus (less than 1%) and a few group-B streptococci gave negative results. By the co-agglutination method, positive reactions appeared immediately and were unmistakable, and no false-negative results were obtained. Agglutination grouping, by either that most commercial method, has the enormous can be even after used at high dilutions, antisera, absorption, thus giving considerable economy. In the course of the experiments, however, it became obvious that it was not necessary to use separate staphylococcal suspensions to which each of the group antibodies had been adsorbed; and antiserum and the staphylococcal suspension could be added separately (and in either order) to the trypsinised suspension of streptococci or to streptococci that had been grown in the presence of trypsin, and co-agglutination occurred instantly. It is customary to use the staphylococcal strain Cowan I (no. NCTC8530) for co-agglutination tests, but we found that 6 of 12 randomly chosen strains of Staph. aureus acted equally well. Staphylococci grown in broth or on agar and washed once in physiological saline solution were suitable. The small-scale production of antisera for agglutination grouping by clinical microbiology laboratories would be a serious burden. If, however, commercial manufacturers provided such sera, the microbiologist could choose between the conventional agglutination test (and add the staphylococcal suspension only if an unexpected negative reaction was
cally
as
adyantage
1. 2.
Rosendal, K. Acta path. microbiol. scand. 1956, 39, 127. Christensen, P., Kahlmeter, G., Jonsson, S., Kronvall, 1973,7, 881.
G.
Infect. Immun
693 inconsistent, and these studies
were abandoned, overby the description of the hepatitis B antigens and, more recently, by animal and immunoelectronmicroscopic observations pertinent to hepatitis A.
obtained) and our modified co-agglutination test for every test.
were
In neither case would he be using reagents with a short shelflife, Workers who use the co-agglutination method to detect other antigen-antibody reactions may also find that the separate addition of antiserum and staphylococcal strain saves them
shadowed
considerable labour. Cross-Infection Reference Laboratory, Ceniral Public Health Laboratory, London NW9 5HT
W. R. MAXTED ANDROULLA EFSTRATIOU M. T. PARKER
SIR,-In bronchial asthma, exercise-induced symptoms can be a disabling and socially restricting feature of the disease.I At a clinic visit a 38-year-old male patient whose main complaint was of wheezing induced by running, also volunteered that he developed similar symptoms during sexual intercourse. The asthmatic features often interfered with the satisfactory completion of coitus and were causing considerable strain on his marital relationship. After this, three further male patients aged 25-40, with exercise-induced asthma, were asked specifically about the possible onset of symptoms during intercourse. All these patients, surprisingly, admitted to considerable sexual difficulties because of the onset of their typical symptoms of wheezing and dyspnrea. None had been asked previously about this feature of their condition, nor had they wished to mention this aspect because of embarrassment. After prophylactic therapy had been started (two with disodium cromoglycate, two with a steroid aerosol), all had a general improvement in their asthma. Two indicated that while on therapy their sexually induced asthmatic symptoms were eliminated, and in the two others the difficulties were considerably modified. The mechanism of this reaction is unlikely to be different from that of asthma initiated by other forms of exercise such as running or cycling. Anxiety and emotional factors may have played a part, but in this group with exercise-induced features predominating, these factors are unlikely to be significant. It is conceivable, however, that sexual activity in bed, by disturbing the surrounding house-dust mite population may provide an allergen challenge in sensitised individuals. It is only through increased awareness and specific questioning that the frequency of angina pectoris occurring during intercourse in patients with coronary heart-disease has been demonstrated.2 "Sexercise" induced asthma may also be common but overlooked both by the family doctor and the respiratory physician. The successful outcome in this group of patients serves to demonstrate the need for a direct approach in those at risk. IAN S. SYMINGTON
JAMES W. KERR
INHIBITION OF PHYTOHÆMAGGLUTININ TRANSFORMATION BY SERUM OF PATIENTS WITH FULMINANT HEPATITIS
Sn,—Dr Dupuy and his colleagues (Sept. 11,
they
were
It may be that inhibition of P.H.A transformation is associated with hepatitis B (4/6 of Dupuy’s cases were known to be associated with hepatitis B) and that the inconsistency encountered in earlier studies was related to our inability properly to identify octiologically distinct varieties of hepatitis. Virus Laboratory, Department of Microbiology, Institute of Child Health, London WC1N 1EH
SEXERCISE-INDUCED ASTHMA
Department of Respiratory Medicine, Western Infirmary and Knightswood Hospital, Glasgow
as
p.
578)
describe the inhibition of phytohasmagglutinin transformation
oy serum of patients with fulminant viral hepatitis. This was ?1 described by Mella and myself in 1967and 1968.4 Subsequently several attempts were made by my laboratory by others to investigate this finding further. The results 1 McNeill, R S., Nairn, J. R., Millar, J. S., Nairn, C. G. Q. Jl Med. 1966,
137, 55 2 Hellerstein, H. K., Fnedman, E. H. Archs intern. Med. 1970, 125, 987. 3 Mell a. B, Lang, D. J. Science, 1967, 155, 80. 4 Mella B, Lang, D. J. Ann N.Y. Acad Sci 1968, 155, 880.
DAVID J. LANG
BREAST IS BEST FOR CORONARY PROTECTION
SiR,—Your contributor (Aug. 21, p. 412) has a hunch that "breast is best", but admits his reasons are largely related to the emotional and behavioural bonding of mother and baby. But he overlooks a wealth of circumstantial evidence which points to coronary protection being a likely benefit of breast
feeding. Non-lipid-containing histological changes in the coronary arteries of infants and young children which are almost certainly predisposing to later atherosclerosis have been described by many pathologists, 1-3 notably Osborn.4These changes have been found in children who have died from gastroenteritis, other infections, or any condition associated with dehydration and collapse, and also in those killed accidentally in whom there was no obvious preceding disease. With a variety of associations, but no proof of causation, they must be referred to as non-specific. Often no doubt, and usually in lowrisk countries in which atherosclerosis and its complications are rare, injury is followed by repair. However, given a later unfavourable nutritional environment in the form of a modern Western-type diet, it is probable that the increased permeability of the arterial wall and changes which predispose to the infiltration, retention, and accumulation of low-density lipoproteins predispose to atherosclerosis. Osborn described the pathological changes in 1500 young people aged 0-20 years. Since serial observations in an individual are impossible, conclusions had to be based on the spectrum of pathological changes from the accumulation of mucopolysaccharides to fully developed atherosclerotic plaques. In infants with no history of relevant preceding disease, causes are likely to be nutritional. He closely questioned more than 100 mothers and concluded that the lesions described were more frequent and severe in the predominantly bottlefed and uncommon or mild in those predominantly breast-fed. Clearly only a prospective study can be conclusive. It is therefore reasonable to consider the differences between human and cow’s milk and the likelihood of their being responsible for the early changes in the coronary arteries. Breast milk has evolved as a perfect and all-sufficient food for the first twelve months of life or longer while cow’s milk has evolved for very different needs. The only similarities in the two varieties lie in the water and, perhaps, the sugar. Total protein in cow’s milk is much higher and its constituent aminoacid pattern is very different. Antibodies are present in the blood of many infants and this immunological response could itself damage the arterial wall and also increase platelet adhesiveness and aggregation which can have harmful effects.6 Cow’s milk is grossly deficient in essential fatty acids. They amount to only 25% of the concentration in human milk in 1. Moon, H. D. Circulation, 1957, 16, 268. 2. Daoud, A. et al. Exp. mol. Path. 1964, 3, 475. 3. Pesonen, E. Atherosclerosis, 1974, 20, 173. 4. Osborn, G. R. Incubation Period of Coronary
Thrombosis; p. 177. London,
1963. 5. Osborne, G. R. Colloq. int. C.N.R.S. 1967, no. 169. 6. Davies, D. F. Am. Heart J. 1971, 81, 289. 7. György, P. Am. J. clin. Nutr. 1971, 24, 970.
