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THE SIZE OF INFLUENZA A VIRUS
526 been removed. If we concede that small fragments may have been overlooked, we should still expect considerable temporary improvement, as in thyrotoxicosis after inadequate thyroidectomy. I suggest that improvement might well be due not to thymectomy, but to the accidental removal of parathyroids in some patients. This would set up a state of latent tetany, counteracting the myasthenia. The favourable action of large doses of guanidine shows that tetany corrects the myoneural disorder of myasthenia. The well-known anatomical aberrations of the parathyroids, which may be found in the thymus and at other sites in the mediastinum and at the base of the neck, exposes them to injury or removal in some patients
during thymectomy. If this suggestion is correct, the serum calcium should be low in the patients who improve, and within the normal range when the operation fails. As I am unlikely to have an adequate number of patients to test this hypothesis, I bring it to the notice of those who’ have suitable opportunities. If investigation confirms my suggestion deliberate parathyroidectomy should obviously supersede thymectomy in the treatment of myasthenia gravis. -
-
L. P. E. LAURENT.
Basingstoke. RELIGIO
MEDICI
SiR,—In Dr. Douglas Guthrie’sexcellent and informative tercentenary tribute (in your issue of Oct. 9) to the author of the first " Religio Medici " there are two points on which I would like to comment. Firstly, Dr. Guthrie states that the book was translated into several languages including Italian. It is true that in a letter to the antiquary, John Aubrey, dated 14 March, 1672-3, Sir Thomas Browne stated that he 44 write- Religio Medici in English, which was since translated into Latin, French, Italian, High and Low Dutch." But up to the present time no contemporary edition in Italian has ever been seen, and it seems that Browne was himself under a misapprehension about this. The statement did not, in fact, become true until the’ appearance of Professor Piccoli’s translation in 1931. Secondly, Dr. Guthrie states that " of the closing years of Browne’s life we have little information." This appears to me to be the very opposite of the truth. The later years of Browne’s life are much more fully documented than any other period by the voluminous and interesting correspondence which has survived. Most of the letters are addressed to his son, Dr. Edward Browne, FRS, and they provide a detailed picture of Browne pursuing his medical practice and scientific interests in Norwich.
London, N.W.3. THE
SIZE
GEOFFREY KEYNES. OF INFLUENZA A
the infective property. Moreover the of the particles from infected lung extracts are similar to those of the normal lung particles and differ only in the superimposition of the antigenic structure of the virus as it occurs in chick allantoic fluid. 4. Extra-embryonic fluid of chicks infected with the virus of influenza A contained the virus in high concentration, but the virus frequently could not be sedimented from such fluid by speeds which would remove all virus activity from mouselung filtrates. These authors spun a mixture of tobaccomosaic virus and influenza virus from allantoic fluid and found that while the tobacco-mosaic virus was almost completely sedimented under their conditions, about, half the influenza virus actively remained in the supernatant. Tobacco-mosaic virus sediments with about the same velocity as a spherical particle of 50 mft of the same density as most viruses. 5. Ultrasonic vibrations increased the infectivity of lungtissue sediments by 10-30 fold, thus suggesting that aggre. gates were being broken up by this means. 6. The infectivity of some of Chambers and Henle’s pre. parations was such that if the infective units were 100 m in diameter, infection could be obtained with considerably less than one particle. 7. Electron micrographs of the isolated virus protein indicate that the pradominating unit is roughly spherical in shape and has a particle diameter of about 11 met.
It seems to me that this evidence is at least as good as much of that which supports the estimates of other virus sizes accepted as established facts. Plant Virus Research Station,
Cambridge.
"
rash " my acceptance as " an established fact ’’ of the American estimate of 15 mft as the diameter of the influenza virus particle, against the English estimate of 100 lift. May I, as briefly as possible, attempt to justify my apparent rashness ? The’two most recent American papers on the size of the influenza virus particle are those by Chambers and Henle (J. exp. Med. 1943, 77, 251) and Chambers, Henle, Lauffer and Anderson (Ibid, p. 265) and I quote freely from them. It would, I think, be agreed that the presence of cell components in a virus preparation casts doubt on all measurements of virus particle size unless the possibility of adsorption of virus on- the larger particles is eliminated. Now the English work on the size of influenza virus was carried out on mouse-lung tissue and the American work on mouse-lung tissue and the extra-embryonic fluids of chicks. The following are the relevant facts : 1. Both infected and normal mouse lung tissue contain of 100 mlt. 2. The infectious unit from tissue suspensions is about 100 mit in diameter and is of the same chemical composition as particles of the same size and abundance separated from normal tissue by an identical procedure. 3. Particles 100 my in diameter separated from normal lung tissue can adsorb the virus completely from the egg fluid
KENNETH M. SMITH.
TREATMENT OF BURNS AT FIRST-AID POSTS SiB,—Would it not be wise to insist on the masking of all dressers who treat. burns at first-aid posts ? In your issue of May 29 Leonard Colebrook describes a case from whose burn haemolytic streptococci were cultivated four hours after it was sustained. Masking of all attendants on this case might well have prevented the infection and resultant delay in healing. Recently I had the chance of hearing of a community of 120 who had nose and throat swabs taken. No less than 70 of these were carriers ; all were feeling healthy and carrying out their routine duties A burn case attended by one of these 70 would probably have been infected. The masking of all nurses attending confinements is no longer an innovation. It is a routine standard to ensure a satisfactory puerperium.’ No-one need suggest the old bogy of frightening the patient; it just does not exist. In my opinion all first-aiders and all dressers and nurses in the hospital casualty departments should automatically mask before attending to burns. C. KIRBY. Smethwick.
VIRUS
SiR,-In the kindly notice of my Pelican book Beyond the Microscope, in your issue of Oct. 2, you stigmatise as
particles
thereby acquire antigenic properties
and
CHILLED
KAOLIN
POULTICE
SIR,-From time to time methods of treatment
are
described which involve the local application of low temperatures.1 I would suggest that some attention should be paid to the value of the local application of chilled kaolin poultices, as this preparation will maintain a low temperature over a long period in the same way that it will maintain a high temperature. The details of the method are as follows : Kaolin poultice is spread on lint to an even thickness of a quarter of an inch. The exposed surface is covered with a layer of gauze to obviate sticking. Three such " cold poulI
tices " are prepared and cut to shape. They are packed in large envelopes or flat X-ray film tins and are chilled in a domestic refrigerator. The poultices are applied one at a time, and are held in place by bandage over a thick layer of cotton-wool. Each is left on until it no longer feels cold ; it is then replaced by a newly chilled one and the discarded one is repacked in its tin or envelope and returned to the refrigerator for re-chilling.
This method is described with some diffidence as use is limited to certain definite indications. But I have used " cold kaolin " since 1938 and am convinced of its value as a simple and easily available means of obtaining a local application of low temperature over a
its
1UU tdIUtl.
W. S. PARKER. 1.
Ungley, C. C. Lancet, 1943, i, 681 ; Allen, F. M. Ibid,
p. 723.
I
during thymectomy. If this suggestion is correct, the serum calcium should be low in the patients who improve, and within the normal range when the operation fails. As I am unlikely to have an adequate number of patients to test this hypothesis, I bring it to the notice of those who’ have suitable opportunities. If investigation confirms my suggestion deliberate parathyroidectomy should obviously supersede thymectomy in the treatment of myasthenia gravis. -
-
L. P. E. LAURENT.
Basingstoke. RELIGIO
MEDICI
SiR,—In Dr. Douglas Guthrie’sexcellent and informative tercentenary tribute (in your issue of Oct. 9) to the author of the first " Religio Medici " there are two points on which I would like to comment. Firstly, Dr. Guthrie states that the book was translated into several languages including Italian. It is true that in a letter to the antiquary, John Aubrey, dated 14 March, 1672-3, Sir Thomas Browne stated that he 44 write- Religio Medici in English, which was since translated into Latin, French, Italian, High and Low Dutch." But up to the present time no contemporary edition in Italian has ever been seen, and it seems that Browne was himself under a misapprehension about this. The statement did not, in fact, become true until the’ appearance of Professor Piccoli’s translation in 1931. Secondly, Dr. Guthrie states that " of the closing years of Browne’s life we have little information." This appears to me to be the very opposite of the truth. The later years of Browne’s life are much more fully documented than any other period by the voluminous and interesting correspondence which has survived. Most of the letters are addressed to his son, Dr. Edward Browne, FRS, and they provide a detailed picture of Browne pursuing his medical practice and scientific interests in Norwich.
London, N.W.3. THE
SIZE
GEOFFREY KEYNES. OF INFLUENZA A
the infective property. Moreover the of the particles from infected lung extracts are similar to those of the normal lung particles and differ only in the superimposition of the antigenic structure of the virus as it occurs in chick allantoic fluid. 4. Extra-embryonic fluid of chicks infected with the virus of influenza A contained the virus in high concentration, but the virus frequently could not be sedimented from such fluid by speeds which would remove all virus activity from mouselung filtrates. These authors spun a mixture of tobaccomosaic virus and influenza virus from allantoic fluid and found that while the tobacco-mosaic virus was almost completely sedimented under their conditions, about, half the influenza virus actively remained in the supernatant. Tobacco-mosaic virus sediments with about the same velocity as a spherical particle of 50 mft of the same density as most viruses. 5. Ultrasonic vibrations increased the infectivity of lungtissue sediments by 10-30 fold, thus suggesting that aggre. gates were being broken up by this means. 6. The infectivity of some of Chambers and Henle’s pre. parations was such that if the infective units were 100 m in diameter, infection could be obtained with considerably less than one particle. 7. Electron micrographs of the isolated virus protein indicate that the pradominating unit is roughly spherical in shape and has a particle diameter of about 11 met.
It seems to me that this evidence is at least as good as much of that which supports the estimates of other virus sizes accepted as established facts. Plant Virus Research Station,
Cambridge.
"
rash " my acceptance as " an established fact ’’ of the American estimate of 15 mft as the diameter of the influenza virus particle, against the English estimate of 100 lift. May I, as briefly as possible, attempt to justify my apparent rashness ? The’two most recent American papers on the size of the influenza virus particle are those by Chambers and Henle (J. exp. Med. 1943, 77, 251) and Chambers, Henle, Lauffer and Anderson (Ibid, p. 265) and I quote freely from them. It would, I think, be agreed that the presence of cell components in a virus preparation casts doubt on all measurements of virus particle size unless the possibility of adsorption of virus on- the larger particles is eliminated. Now the English work on the size of influenza virus was carried out on mouse-lung tissue and the American work on mouse-lung tissue and the extra-embryonic fluids of chicks. The following are the relevant facts : 1. Both infected and normal mouse lung tissue contain of 100 mlt. 2. The infectious unit from tissue suspensions is about 100 mit in diameter and is of the same chemical composition as particles of the same size and abundance separated from normal tissue by an identical procedure. 3. Particles 100 my in diameter separated from normal lung tissue can adsorb the virus completely from the egg fluid
KENNETH M. SMITH.
TREATMENT OF BURNS AT FIRST-AID POSTS SiB,—Would it not be wise to insist on the masking of all dressers who treat. burns at first-aid posts ? In your issue of May 29 Leonard Colebrook describes a case from whose burn haemolytic streptococci were cultivated four hours after it was sustained. Masking of all attendants on this case might well have prevented the infection and resultant delay in healing. Recently I had the chance of hearing of a community of 120 who had nose and throat swabs taken. No less than 70 of these were carriers ; all were feeling healthy and carrying out their routine duties A burn case attended by one of these 70 would probably have been infected. The masking of all nurses attending confinements is no longer an innovation. It is a routine standard to ensure a satisfactory puerperium.’ No-one need suggest the old bogy of frightening the patient; it just does not exist. In my opinion all first-aiders and all dressers and nurses in the hospital casualty departments should automatically mask before attending to burns. C. KIRBY. Smethwick.
VIRUS
SiR,-In the kindly notice of my Pelican book Beyond the Microscope, in your issue of Oct. 2, you stigmatise as
particles
thereby acquire antigenic properties
and
CHILLED
KAOLIN
POULTICE
SIR,-From time to time methods of treatment
are
described which involve the local application of low temperatures.1 I would suggest that some attention should be paid to the value of the local application of chilled kaolin poultices, as this preparation will maintain a low temperature over a long period in the same way that it will maintain a high temperature. The details of the method are as follows : Kaolin poultice is spread on lint to an even thickness of a quarter of an inch. The exposed surface is covered with a layer of gauze to obviate sticking. Three such " cold poulI
tices " are prepared and cut to shape. They are packed in large envelopes or flat X-ray film tins and are chilled in a domestic refrigerator. The poultices are applied one at a time, and are held in place by bandage over a thick layer of cotton-wool. Each is left on until it no longer feels cold ; it is then replaced by a newly chilled one and the discarded one is repacked in its tin or envelope and returned to the refrigerator for re-chilling.
This method is described with some diffidence as use is limited to certain definite indications. But I have used " cold kaolin " since 1938 and am convinced of its value as a simple and easily available means of obtaining a local application of low temperature over a
its
1UU tdIUtl.
W. S. PARKER. 1.
Ungley, C. C. Lancet, 1943, i, 681 ; Allen, F. M. Ibid,
p. 723.
I