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PARA-AMINOSALICYLIC ACID IN THE TREATMENT OF TUBERCULOSIS
15 EFFECT OF 1-6 MG. SODIUM SALICYLATE ON THE OXYGEN UPTAKE OF DIFFERENT PATHOGENIC AND NONPATHOGENIC HUMAN AND BOVINE STRAINS OF THE TUBERCLE BACILLUS .
decreased
the activity considerably. If the group was placed in position 3 instead of 2 the effect was diminished. If the carboxy group was replaced by a sulphonic acid group the activity was abolished. Substitutions in the carboxy group (methyl, ethyl, and furfuranylanhydride) changed the activity only slightly. Double molecules of 4-aminosalicylic acid linked together at position 3 were as effective as 4-aminosalicylic acid but highly toxic to animals. Animal experiments showed that 4-aminosalicylic acid was not toxic to rats when given for 1-2 months in a concentration of 5% in a synthetic food. A blood concentration of 3-7 mg. of free aminosalicylic acid per 100 c.cm. was found when analysed by Ehrlich’s group
hydroxy
reagent. Guineapigs dimethylaminobenzaldehyde decrease in appetite sensitive they showed were
more
and in
globin pigs. *
as
a
No changes in the blood-cells or hmmoobserved either in the rats or in the guineaThe substance could be administered by mouth,
growth.
were
Within the limits of about ± 5%.
It cannot as yet be decided whether benzoates and salicylates act as catalysers or as metabolites. If the latter is the case it must be assumed that the pathogenic strains can open the benzene ring in these compounds. The differences found seem to open up new pathways for studying the biochemistry of the pathogenicity of the
tubercle bacillus. On the basis of the stimulative effect of benzoates and salicylates more than 50 derivatives of these substances were investigated for their inhibitory effect on the growth of tubercle bacilli (competitive enzyme inhibition). Preliminary results of these experimentsbacteriological as well as clinical-are present,ed in an accompanying paper (Lehmann 1946) with special regard to p-aminoaalicylic acid as the most effective inhibitor. REFERENCES
Bernheim, F. (1941) J. Bact. 41, 387.
Dieckmann, H., Mohr, H. (1933), Zbl. Bakt. 129, 185. Lehmann, J. (1946) Lancet, i, 15. Loebel, R. O., Shorr, E., Richardson, H. B. (1933) J. Bact. 26, 167. Nakamura, T. (1938) Tohuku J. exp. Med. 34, 231.
Preliminary
Communication
PARA-AMINOSALICYLIC ACID IN THE TREATMENT OF TUBERCULOSIS IN 1940 Bernheimshowed that salicylic (2-hydroxybenzoic) acid and benzoic acid increase the oxygen consumption and carbon-dioxide production of the tubercle bacillus, whereas the homologues 3- and 4hydroxybenzoic acid were inactive. It was concluded that salicylic and benzoic acids were oxidised as metabolites and that similar chemical configurations possibly play a part in the metabolism of the bacillus. On the basis of these experiments I have investigated more than 50 derivatives of benzoic acid with the purpose of finding a substance possessing bacteriostatic properties against the tubercle bacillus. The substances were synthesised by K. G. Rosdahl, of Ferrosan Co., Malmo. An attenuated bovine strain (B.C.G.) grown on Souton’s medium was used for the experiments. The substances investigated were added to the medium in concentrations from 10-2 to 10-6 mol. The area, or the dry weight, of the bacilli was determined when the surface of the control flasks (100 ml. medium in 250 ml. flasks) was covered with a somewhat packed film of the bacillii.e., after 12-20 days. The most active substance found was 4-aminosalicylic acid (p-aminosalicylic acid) producing an inhibition of 50-75% in a concentration of 10-" mol. (1 in 650,000 or 0-15 mg. per 100 c.cm.). The bacteriostatic effect was completely abolished if the amino group was placed in position 3 or 5, or if its place was taken by N0. Substitutions in the 4-amino group (by C]EI, or stearic acid) reduced the bacteriostatic effect only slightly or not at all. If the hydroxy group in the 2- position was replaced by CH, activity was retained, but not if it was replaced by NH2 or Cl. Substitutions in the hydroxy
1.
Bernheim, F. Science, 1940, 92, 204.
Fig. I-Chart in
case
1, showing effect of third aminosalicylic acid.
course
of para-
subcutaneously, intramuscularly, or intravenously. The treatment of experimental tuberculosis in guineapigs and rats is in progress. Clinical trial.-The treatment of tuberculosis in man started parallel with the animal experiments. was Tuberculous abscesses after thoracoplasty up to 50-60 ml. in volume have been treated daily with a neutral 10% solution of p-aminosalicylic acid and showed healing after some months even when they had remained unchanged for 3-6 months before treatment. It has been given by mouth to 20 patients since March, 1944, at the Renstroemska Sanatorium in Gothenburg (Superintendent Dr. G. Vallentin). A blood concentration of 2-7 mg. per 100 c.cm. was achieved by giving 10-15 g. a day. Periods of 8 days’ treatment were followed by free intervals of 8 days. It is too early to follow up the results. In many cases, however, a prompt fall in temperature-temporary or permanent--coincided with the periods of treatment and was accompanied by
-
Fig. 2-Chart in
case
2.
improvement in the patient’s general condition as indicated by a gain in appetite and weight, an increase in the red cells and haemoglobin and a decrease in the erythrocyte sedimentation-rate. Two illustrative cases follow. CASE 1.-A woman, aged 24. Onset of tuberculosis in May-June, 1944. X-ray examination on July 3, 1944, showed an acute general dissemination of cloudy processes in both lungs. Remittent fever 975°-1015° F from July 3 to Nov. 26, when treatment with p-aminosalicylic acid (P.A.S.) was given in three periods with concomitant falls in temperature ; the last period is illustrated in fig. 1. Normal
temperature has been maintained up
to the
present since this
‘
16 treatment.
1945,
on
Artificial pneumothorax instituted on March 7, the right side for an apical cavity 1-1 in. in
diameter. CASE 2.-A man, aged 35. Bilateral pleural effusion; onset June, 1944. Guineapig test positive on the exudate from both sides. No manifest tuberculosis in the lungs. r.A.S. treatment started Feb. 16, 1945, followed by general improvement (fig. 2). Gain in weight 15t lb. in two months. None of the usual effects of salicylates (sweats, ear symptoms) were observed even with a high dosage The fall in of p-aminosalicylic acid (15 g. daily). temperature was therefore thought not to be due to a
salicylate
effect.
The work here recorded was done at the Sahlgrenska Hospital, at the Research Laboratories of the Ferrosan Co. at Maimo, and at the Renstroemska Sanatorium, Gothenburg. JÖRGEN LEHMANN, Sahlgrenska Hospital, Gothenburg, Sweden.
Medical Societies ROYAL AT
a
SOCIETY OF TROPICAL MEDICINE AND HYGIENE meeting of the society on Dec. 13 with Dr. C. M.
WENYON, F.R.S., the president, in the chair, on
the
Teaching
of
Tropical
a
discussion
Medicine Dr. L. E. NAPIER, who said that in the United States of America a serious attempt is being made both to improve the teaching of the subject to the undergraduate and also to develop its postgraduate teaching. In Great Britain, however, tropical medicine appears to have been relegated to the place of a specialty about which the general practitioner need know nothing and with which the ordinary student need not be burdened. These shortcomings require remedying urgently. To avoid overloading the undergraduate curriculum the student should be introduced in his premedical years to selected parasites of man, and the essential clinical diagnostic methods used in tropical medicine should be included in the teaching of clinical pathology. This would leave the pathology, symptomatology, and therapeutics of important tropical diseases to be taught in the systematic lectures on medicine and in the clinical departments as the occasion arose. At this stage it seems entirely wrong to segregate tropical medicine as it has been segregated in the past and to teach the student virtually nothing of the pathology, symptomatology, and therapeutics of tropical diseases. Tropical diseases furthermore could provide excellent examples for teaching the general principles of preventive medicine. Scarcity of clinical material must not be used as an excuse for avoiding clinical teaching ; the student of general medicine fails to see examples of many diseases which he will be expected to diagnose and treat later in his practice. Much can be done by the use of lantern slides and cinema films. The future will also bring an increasing number of tropical diseases among those whom the war has taken to the tropics, while rapid air transport may allow cases of tropical disease to enter the country unsuspected during the incubation period. Interest in tropical medicine must be fostered by all means. Shortterm exchanges of personnel, research-workers, and teachers between this country and the tropics should be encouraged. As an artificial way of maintaining interest in tropical diseases examining bodies should demand a sound knowledge of the commoner tropical diseases. Turning to postgraduate teaching Dr. Napier said there are few if any places in the world where one can see a better selection of tropical diseases than in London, but owing to the war there is at present no suitable hospital where the available clinical material can be collected ; a crying need today is for a "tropical medical centre." Special provision should be made for those who are proposing to specialise in tropical hygiene. Dr. Napier ended by emphasising the necessity for making the undergraduate and his teachers conscious of the existence of tropical diseases, and for the early establishment of a hospital in London that would act as a centre for teaching and research in tropical medicine ; meanwhile the society should prepare a memorandum on the teaching of tropical medicine and try to obtain representation on all committees considering the matter. was
opened by
Sir PHILIP MANSON-BAHR thought that the medical student’s burdens should be not increased, but agreed that more emphasis should be laid in the premedical studies on the parasites associated with disease in man. He disagreed wiqh the statement that tropical medicine is entirely neglected in the present undergraduate curriculum, pointing out that in practically every medical school in London lectures on tropical diseases are already given to the undergraduate, and that in the examinations of the last few years questions on the more important diseases have always been included. In the postgraduate courses it is also necessary to avoid overloading the curriculum. The best days of teaching tropical medicine were those when the tropical school was a compact selfcontained unit, with the laboratory and clinical work closely linked ; a plethora of visiting lecturers, however specialised their knowledge, leads to overlapping and overloading of the curriculum. In teaching tropical medicine differential diagnosis is most important, and the practical value of microscopy cannot be overstressed. Any difficulty of obtaining clinical material would largely be overcome if the general hospitals were more willing to transfer tropical cases to a tropical’ hospital for
teaching
purposes.
,
Prof. R. M. GORDON also agreed that the course in zoology should include the simpler parasitology of man, and that the teaching of tropical medicine should be extended, especially in the undergraduate’s final year. The graduate student would then require an amplification of his general knowledge, and such teaching would be well covered by the present D.T.M. &H. course, which does not make a specialist but only a good practitioner for the tropics. He did not believe that the situation in which tropical medicine finds itself in London now that the war is over necessarily means that the subject is in danger throughout the country ; the Liverpool School flourished during the war and is confident of its own future. The dearth of living material in this country for the teaching of parasitology and entomology necessitates the artificial maintenance of strains. This involves much labour, and loss of a strain is a disaster unless it is maintained in more than one place ; some institution, such as the Wellcome Laboratories of Tropical Medicine, should interest itself in this matter. The Colonial Office and all firms operating in the tropics should insist on a diploma in tropical medicine for their medical officers. Dr. G. MACDONALD supported broadening the undergraduate curriculum to include more instruction in tropical medicine. He did not admit that the teaching of tropical medicine in London is in a parlous state, but he urged the restoration of facilities lost directly owing to the war and deplored that, outside the special group of those intimately concerned with tropical medicine, interest in the subject has been lost, even the writers of the Goodenough report failing to consider the matter seriously. There must be a centre of clinical research in London to replace that lost in the war, but on a better and more fully equipped scale, and it should cooperate with the existing School of Tropical Medicine as now constituted. Postgraduate teaching in tropical medicine should round off a general medical education and fit the student to practise medicine in the tropics, rather than create a specialist ; the specialist requires, in addition to
special knowledge of tropical diseases; a high qualification in general clinical medicine. Similarly those specialising in tropical hygiene should hold a D.P.H. as a basis, supplemented by a D.T.M. & H. and experience overseas before taking up independent work in tropical hygiene. The society should form a policy committee to examine and foster the development, teaching, and standards required in tropical medicine and hygiene. Lieut.-Colonel VERE HODGE, while agreeing that the establishment of an Imperial centre for tropical medicine should be the ultimate object, thought that immediate steps are required to deal with the large numbers of repatriates who may be returning with latent tropical infections ; after a long absence from home these persons will not want to be sequestrated in special centres, and this will necessitate a number of tropical units throughout the country. The limitations of teaching tropical medicine in this country will make it necessary to have subsidiary centres abroad, but even short courses in this country would give practitioners going abroad an advantage. Three types of teaching in tropical medicine are
decreased
the activity considerably. If the group was placed in position 3 instead of 2 the effect was diminished. If the carboxy group was replaced by a sulphonic acid group the activity was abolished. Substitutions in the carboxy group (methyl, ethyl, and furfuranylanhydride) changed the activity only slightly. Double molecules of 4-aminosalicylic acid linked together at position 3 were as effective as 4-aminosalicylic acid but highly toxic to animals. Animal experiments showed that 4-aminosalicylic acid was not toxic to rats when given for 1-2 months in a concentration of 5% in a synthetic food. A blood concentration of 3-7 mg. of free aminosalicylic acid per 100 c.cm. was found when analysed by Ehrlich’s group
hydroxy
reagent. Guineapigs dimethylaminobenzaldehyde decrease in appetite sensitive they showed were
more
and in
globin pigs. *
as
a
No changes in the blood-cells or hmmoobserved either in the rats or in the guineaThe substance could be administered by mouth,
growth.
were
Within the limits of about ± 5%.
It cannot as yet be decided whether benzoates and salicylates act as catalysers or as metabolites. If the latter is the case it must be assumed that the pathogenic strains can open the benzene ring in these compounds. The differences found seem to open up new pathways for studying the biochemistry of the pathogenicity of the
tubercle bacillus. On the basis of the stimulative effect of benzoates and salicylates more than 50 derivatives of these substances were investigated for their inhibitory effect on the growth of tubercle bacilli (competitive enzyme inhibition). Preliminary results of these experimentsbacteriological as well as clinical-are present,ed in an accompanying paper (Lehmann 1946) with special regard to p-aminoaalicylic acid as the most effective inhibitor. REFERENCES
Bernheim, F. (1941) J. Bact. 41, 387.
Dieckmann, H., Mohr, H. (1933), Zbl. Bakt. 129, 185. Lehmann, J. (1946) Lancet, i, 15. Loebel, R. O., Shorr, E., Richardson, H. B. (1933) J. Bact. 26, 167. Nakamura, T. (1938) Tohuku J. exp. Med. 34, 231.
Preliminary
Communication
PARA-AMINOSALICYLIC ACID IN THE TREATMENT OF TUBERCULOSIS IN 1940 Bernheimshowed that salicylic (2-hydroxybenzoic) acid and benzoic acid increase the oxygen consumption and carbon-dioxide production of the tubercle bacillus, whereas the homologues 3- and 4hydroxybenzoic acid were inactive. It was concluded that salicylic and benzoic acids were oxidised as metabolites and that similar chemical configurations possibly play a part in the metabolism of the bacillus. On the basis of these experiments I have investigated more than 50 derivatives of benzoic acid with the purpose of finding a substance possessing bacteriostatic properties against the tubercle bacillus. The substances were synthesised by K. G. Rosdahl, of Ferrosan Co., Malmo. An attenuated bovine strain (B.C.G.) grown on Souton’s medium was used for the experiments. The substances investigated were added to the medium in concentrations from 10-2 to 10-6 mol. The area, or the dry weight, of the bacilli was determined when the surface of the control flasks (100 ml. medium in 250 ml. flasks) was covered with a somewhat packed film of the bacillii.e., after 12-20 days. The most active substance found was 4-aminosalicylic acid (p-aminosalicylic acid) producing an inhibition of 50-75% in a concentration of 10-" mol. (1 in 650,000 or 0-15 mg. per 100 c.cm.). The bacteriostatic effect was completely abolished if the amino group was placed in position 3 or 5, or if its place was taken by N0. Substitutions in the 4-amino group (by C]EI, or stearic acid) reduced the bacteriostatic effect only slightly or not at all. If the hydroxy group in the 2- position was replaced by CH, activity was retained, but not if it was replaced by NH2 or Cl. Substitutions in the hydroxy
1.
Bernheim, F. Science, 1940, 92, 204.
Fig. I-Chart in
case
1, showing effect of third aminosalicylic acid.
course
of para-
subcutaneously, intramuscularly, or intravenously. The treatment of experimental tuberculosis in guineapigs and rats is in progress. Clinical trial.-The treatment of tuberculosis in man started parallel with the animal experiments. was Tuberculous abscesses after thoracoplasty up to 50-60 ml. in volume have been treated daily with a neutral 10% solution of p-aminosalicylic acid and showed healing after some months even when they had remained unchanged for 3-6 months before treatment. It has been given by mouth to 20 patients since March, 1944, at the Renstroemska Sanatorium in Gothenburg (Superintendent Dr. G. Vallentin). A blood concentration of 2-7 mg. per 100 c.cm. was achieved by giving 10-15 g. a day. Periods of 8 days’ treatment were followed by free intervals of 8 days. It is too early to follow up the results. In many cases, however, a prompt fall in temperature-temporary or permanent--coincided with the periods of treatment and was accompanied by
-
Fig. 2-Chart in
case
2.
improvement in the patient’s general condition as indicated by a gain in appetite and weight, an increase in the red cells and haemoglobin and a decrease in the erythrocyte sedimentation-rate. Two illustrative cases follow. CASE 1.-A woman, aged 24. Onset of tuberculosis in May-June, 1944. X-ray examination on July 3, 1944, showed an acute general dissemination of cloudy processes in both lungs. Remittent fever 975°-1015° F from July 3 to Nov. 26, when treatment with p-aminosalicylic acid (P.A.S.) was given in three periods with concomitant falls in temperature ; the last period is illustrated in fig. 1. Normal
temperature has been maintained up
to the
present since this
‘
16 treatment.
1945,
on
Artificial pneumothorax instituted on March 7, the right side for an apical cavity 1-1 in. in
diameter. CASE 2.-A man, aged 35. Bilateral pleural effusion; onset June, 1944. Guineapig test positive on the exudate from both sides. No manifest tuberculosis in the lungs. r.A.S. treatment started Feb. 16, 1945, followed by general improvement (fig. 2). Gain in weight 15t lb. in two months. None of the usual effects of salicylates (sweats, ear symptoms) were observed even with a high dosage The fall in of p-aminosalicylic acid (15 g. daily). temperature was therefore thought not to be due to a
salicylate
effect.
The work here recorded was done at the Sahlgrenska Hospital, at the Research Laboratories of the Ferrosan Co. at Maimo, and at the Renstroemska Sanatorium, Gothenburg. JÖRGEN LEHMANN, Sahlgrenska Hospital, Gothenburg, Sweden.
Medical Societies ROYAL AT
a
SOCIETY OF TROPICAL MEDICINE AND HYGIENE meeting of the society on Dec. 13 with Dr. C. M.
WENYON, F.R.S., the president, in the chair, on
the
Teaching
of
Tropical
a
discussion
Medicine Dr. L. E. NAPIER, who said that in the United States of America a serious attempt is being made both to improve the teaching of the subject to the undergraduate and also to develop its postgraduate teaching. In Great Britain, however, tropical medicine appears to have been relegated to the place of a specialty about which the general practitioner need know nothing and with which the ordinary student need not be burdened. These shortcomings require remedying urgently. To avoid overloading the undergraduate curriculum the student should be introduced in his premedical years to selected parasites of man, and the essential clinical diagnostic methods used in tropical medicine should be included in the teaching of clinical pathology. This would leave the pathology, symptomatology, and therapeutics of important tropical diseases to be taught in the systematic lectures on medicine and in the clinical departments as the occasion arose. At this stage it seems entirely wrong to segregate tropical medicine as it has been segregated in the past and to teach the student virtually nothing of the pathology, symptomatology, and therapeutics of tropical diseases. Tropical diseases furthermore could provide excellent examples for teaching the general principles of preventive medicine. Scarcity of clinical material must not be used as an excuse for avoiding clinical teaching ; the student of general medicine fails to see examples of many diseases which he will be expected to diagnose and treat later in his practice. Much can be done by the use of lantern slides and cinema films. The future will also bring an increasing number of tropical diseases among those whom the war has taken to the tropics, while rapid air transport may allow cases of tropical disease to enter the country unsuspected during the incubation period. Interest in tropical medicine must be fostered by all means. Shortterm exchanges of personnel, research-workers, and teachers between this country and the tropics should be encouraged. As an artificial way of maintaining interest in tropical diseases examining bodies should demand a sound knowledge of the commoner tropical diseases. Turning to postgraduate teaching Dr. Napier said there are few if any places in the world where one can see a better selection of tropical diseases than in London, but owing to the war there is at present no suitable hospital where the available clinical material can be collected ; a crying need today is for a "tropical medical centre." Special provision should be made for those who are proposing to specialise in tropical hygiene. Dr. Napier ended by emphasising the necessity for making the undergraduate and his teachers conscious of the existence of tropical diseases, and for the early establishment of a hospital in London that would act as a centre for teaching and research in tropical medicine ; meanwhile the society should prepare a memorandum on the teaching of tropical medicine and try to obtain representation on all committees considering the matter. was
opened by
Sir PHILIP MANSON-BAHR thought that the medical student’s burdens should be not increased, but agreed that more emphasis should be laid in the premedical studies on the parasites associated with disease in man. He disagreed wiqh the statement that tropical medicine is entirely neglected in the present undergraduate curriculum, pointing out that in practically every medical school in London lectures on tropical diseases are already given to the undergraduate, and that in the examinations of the last few years questions on the more important diseases have always been included. In the postgraduate courses it is also necessary to avoid overloading the curriculum. The best days of teaching tropical medicine were those when the tropical school was a compact selfcontained unit, with the laboratory and clinical work closely linked ; a plethora of visiting lecturers, however specialised their knowledge, leads to overlapping and overloading of the curriculum. In teaching tropical medicine differential diagnosis is most important, and the practical value of microscopy cannot be overstressed. Any difficulty of obtaining clinical material would largely be overcome if the general hospitals were more willing to transfer tropical cases to a tropical’ hospital for
teaching
purposes.
,
Prof. R. M. GORDON also agreed that the course in zoology should include the simpler parasitology of man, and that the teaching of tropical medicine should be extended, especially in the undergraduate’s final year. The graduate student would then require an amplification of his general knowledge, and such teaching would be well covered by the present D.T.M. &H. course, which does not make a specialist but only a good practitioner for the tropics. He did not believe that the situation in which tropical medicine finds itself in London now that the war is over necessarily means that the subject is in danger throughout the country ; the Liverpool School flourished during the war and is confident of its own future. The dearth of living material in this country for the teaching of parasitology and entomology necessitates the artificial maintenance of strains. This involves much labour, and loss of a strain is a disaster unless it is maintained in more than one place ; some institution, such as the Wellcome Laboratories of Tropical Medicine, should interest itself in this matter. The Colonial Office and all firms operating in the tropics should insist on a diploma in tropical medicine for their medical officers. Dr. G. MACDONALD supported broadening the undergraduate curriculum to include more instruction in tropical medicine. He did not admit that the teaching of tropical medicine in London is in a parlous state, but he urged the restoration of facilities lost directly owing to the war and deplored that, outside the special group of those intimately concerned with tropical medicine, interest in the subject has been lost, even the writers of the Goodenough report failing to consider the matter seriously. There must be a centre of clinical research in London to replace that lost in the war, but on a better and more fully equipped scale, and it should cooperate with the existing School of Tropical Medicine as now constituted. Postgraduate teaching in tropical medicine should round off a general medical education and fit the student to practise medicine in the tropics, rather than create a specialist ; the specialist requires, in addition to
special knowledge of tropical diseases; a high qualification in general clinical medicine. Similarly those specialising in tropical hygiene should hold a D.P.H. as a basis, supplemented by a D.T.M. & H. and experience overseas before taking up independent work in tropical hygiene. The society should form a policy committee to examine and foster the development, teaching, and standards required in tropical medicine and hygiene. Lieut.-Colonel VERE HODGE, while agreeing that the establishment of an Imperial centre for tropical medicine should be the ultimate object, thought that immediate steps are required to deal with the large numbers of repatriates who may be returning with latent tropical infections ; after a long absence from home these persons will not want to be sequestrated in special centres, and this will necessitate a number of tropical units throughout the country. The limitations of teaching tropical medicine in this country will make it necessary to have subsidiary centres abroad, but even short courses in this country would give practitioners going abroad an advantage. Three types of teaching in tropical medicine are