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The use of carbon monoxide to prevent sickle-cell formation.
971
Summary months, was admitted
to hospital, with due to vaccinia gangrenosa hypogammaglobutinaemia, 5 weeks after vaccination. He was treated by replacement therapy with postvaccinial gamma-globulin, by foetal lymphatic-tissue transplants, and by skin homografts.
A
boy, aged
7
N-methylisatin -thiosemicarbazone (compound 33/T/ 57) was given orally. His condition deteriorated steadily and he died 20 days after admission. The indications of hypogammaglobulinsemia are given, and exclusion of affected individuals from vaccination programmes is advised. The
treatment
grateful
of
our
patient is discussed.
am
to
Prof. J. R.
Squire,
of the
Preliminary
department
to
Communications
THE sickling phenomena of erythrocytes was first observed by Herrickin 1910. Reversion of the cell to normal discoidal form with increasing oxygen tension has been examined by Sherman2 and Harris et al.3 The present study was undertaken to establish whether other ligands-such as carbon monoxide and nitric oxidewould also reverse sickling, and to explore the possibility of reducing the degree of sickle-cell formation in vivo by a
N. Amer.
Hutchinson, J. (1879) Brit. med. J. ii, 960. Keidan, S. E., McCarthy, K., Haworth, J. C. (1953)
Arch. Dis. Childh.
7,
28,
110.
Kempe, Martin,
C. H. (1960) Pediatrics, 26, 176. C. M., Waite, J. B., McCullough, N. B. (1957)
J. clin. Invest. 36,
405.
Medical Research Council committee (1962) Lancet, i, 873.
0-2 g. sodium bicarbonate, and 0-24 g. calcium chloride per litre), and the 1 in 50 suspension was reduced in a similar manner but without any carbon dioxide. In this case the completely reduced cells at pH 8 remained perfectly discoidal, demonstrating the decrease of sickling with increasing pH.
potassium chloride,
THE USE OF CARBON MONOXIDE TO PREVENT SICKLE-CELL FORMATION
supplementing oxygen with
REFERENCES
Bauer, D. J., Sadler, P. W. (1960) Lancet, i, 1110. Bruton, O. C. (1952) Pediatrics, 9, 722. Good, E., Zak, S., Condie, R., Bridges, R. (1960) Pediat. Clin. 397.
of experiDr. J. F. Soothill, for help with gamma-globulin estimations; to Dr. H. W. Bunje for supplies of postvaccinial gamma-globulin; to Dr. D. J. Bauer of the Wellcome Institute for advice and supply of compound
I
mental pathology, Birmingham University, for his advice;
33/T/57; to Mr. D. C. Bodenham, of the Frenchay Hospital, Bristol, for supply of stored skin; and to Dr. G. H. Tovey and Dr. N. F. W. Brueton of the blood-transfusion centre, Southmead Hospital, Bristol, for their kindness in supplying the foetal tissue, and assessment of red-cell survival. I also thank Dr. G. Stewart-Smith of Exeter for postmortem studies, and his department (particularly Miss M. McCready) for plasmaprotein electrophoresis; and Dr. Brendan Moore for the virology studies and advice. I am particularly indebted to Dr. F. S. W. Brimblecombe of Exeter for permission to publish details of this case, and for his encouragement and advice throughout.
on the oxygen tension and in the percentage saturation of the cell-haemoglobin.23 A typical curve obtained with the patient’s blood is shown in the figure. The oxygen tension was slowly reduced by equilibrating
The
degree of sickling depends
turn on
low concentration of carbon
monoxide. THE PATIENT
The subject was a male West Indian, from Grenada, aged 29. The symptoms were ulcers on both legs, some blurring of vision in the left eye, and occasional attacks of epistaxis and dizziness. Otherwise the patient’s health was relatively good, and he worked as a dishwasher in a restaurant. There was no history of bone pain or abdominal pain, and no evidence of neurological disorders or jaundice. The spleen was not palpable and there was no evidence of enlargement on X-ray. Microscopical examination of a venous blood-sample revealed sickle cells, and complete sickling occurred on addition of isotonic on a starch hydrosulphite. Electrophoresis of the block, with barbiturate buffer, pH 8-6, showed 97-98% Hb S, 15%Hb A2 and less than 1% Hb F. This would suggest a homozygote for Hb S, though a combination of Hb S and thalassxmia cannot be completely excluded. No relatives were available for examination of this possibility. The haemoglobin level remained 9-10 g. per 100 ml., with persistent reticulocytosis of 8-25%.
haemoglobin
MEASUREMENTS IN VITRO
A
sample of blood, obtained by venepuncture, was slowly reduced in a tonometer by repeated flushing and shaking with a gas mixture of oxygen-free nitrogen and 50 mm. Hg partial pressure of carbon dioxide. Microscopical examination revealed 100% sickling. Three samples of the reduced cells were then taken and separately with oxygen, carbon monoxide, and nitric oxide, air being excluded. In all three cases the sickle cells reverted to the discoidal form. In another experiment 10 ml. of whole blood was added to 490 ml. of RingerLocke solution (composition 9 g. sodium chloride, 0-42 g.
saturated
1 Herrick, J. B. Arch. intern. Med. 1910, 6, 517. 2. Sherman, I. J. Bull. Johns Hopk. Hosp. 1940, 67, 309. 3. Harris, J. W., Brewster, H. H., Ham, T. H., Castle, W. B. Arch. intern. Med. 1956, 97, 145.
Partial pressure oF oxygen A
(mm.Hg)
showing the relation between the percentage of sickle cells and partial pressure of oxygen obtained with the patient’s blood. curve
the whole blood in a tonometer at 37°C with known mixtures of air and nitrogen while maintaining a constant partial pressure of 50 mm. Hg of carbon dioxide. Samples of the blood were taken, avoiding contact with air, and fixed in a solution of 0-85 g. of sodium chloride in 100 ml. of 10% formaldehyde. The percentage of sickle cells was then ascertained by counting, on a wet-slide preparation, under a microscope. The reversibility of sickle cells when saturated with carbon monoxide suggested that the degree of sickling would depend on the proportion of carbon-monoxide haemoglobin (COHb), in a similar manner to that of oxygen (see figure). If carbon monoxide and oxygen are used together the combined effect could be calculated by using the Haldane principles5 in the presence of a low concentration of carbon monoxide, of the order 0-0050-01%, a proportion of the haemoglobin (5-10%) is converted to COHb. Because of the slow dissociation of COHb (a half-life of 250 minutes has recently been estimated by Roughton 6), this is not significantly changed as the blood flows through regions of low oxygen tension in the venous system. The 4. 5.
Douglas, C. G., Haldane,J. S., Haldane, J. B. S. J.Physiol. 1912, 44, 275. Roughton, F. J. W. The Regulation of Human Respiration (J. S. Haldane Centenary Symposium); p. 33. Oxford, 1963.
6. Roughton, F. T. W. Brit. med. Bull. 1963, 19, 80.
972
however, behaves as if the dissociation curve had been the left, combining and dissociating freely with the haemoglobin not immobilised by carbon monoxide. If for example the venous oxygen tension fell to 30 mm. Hg pp., the corresponding degree of oxyhasmoglobin (02Hb) saturation would be 40%. If 5%COHb is present, the effective XHb (i.e., COHb and 02Hb) saturation with 30 mm. Hg pp. of
oxygen,
shifted
to
oxygen is raised to 56%. The percentage of sickle cells should thus be correspondingly reduced in the presence of COHb. To test this possibility a sample of blood was equilibrated in a tonometer at 37°C by shaking and flushing with a mixture of air, nitrogen, and carbon dioxide, corresponding approximately to a mean arterial-venous environment. An examination of the cells showed, as would be expected from the figure, an incidence of 19-5% sickle cells. The same cells were then equilibrated with the above gas mixture containing in addition 0-08 mm. pp. Hg of carbon monoxide. Upon fixing in formaldehyde solution and re-examining the cells, only 6% sickle cells were present. This is consistent with having added an equivalent partial pressure of oxygen along the abscissa of the figure. MEASUREMENTS
IN
VIVO
The next stage of the observations was to examine if the reduction of sickling after adding a low concentration of carbon monoxide could be obtained in vivo. A mask was fitted over the mouth and nose of the patient so that air was breathed from a closed-circuit Benedict spirometer. Oxygen was supplied to the bell at a rate sufficient to maintain the recorder pen at a steady level (approximately 200 ml. per minute). After allowing several minutes for the patient to settle down and for his breathing to become regular, a blood-sample was taken by venepuncture. This was quickly transferred to the formaldehyde fixing solution. Carbon monoxide was then injected slowly into the plastic tubing supplying oxygen to the bell, over a period of thirty minutes, using a 50 ml. syringe and needle. A total of 25 ml. of carbon monoxide was admitted, corresponding to an estimated 4% saturation of COHb in the red cells. The mask was removed, and the patient was allowed to breathe atmospheric air for several minutes. A second blood-sample was then taken by venepuncture and fixed in formaldehyde solution. Microscopical examination disclosed an initial concentration of 10-2% sickle cells with a standard deviation of ±2-5%, and only 3’9±1’5% sickle cells after the addition of carbon monoxide (P < 0-05). An unusual aspect of these measurements is the relatively low number of sickle cells observed initially. Sherman2 has reported sixteen tests on eleven patients with sickle-cell anaemia, with the degree of venous sickling between 30% and 60%. In the present measurements no particular precautions were taken to exclude air, since both samples would be similarly exposed, and any change to normal form takes at least two minutes,the venepuncture and transfer to the formaldehyde solution being completed well within this interval. This point would require further examination, but if a change did occur during this procedure the error would be to minimise any difference between the samples, and so the figures quoted would represent the minimum benefit a small concentration of carbon monoxide would achieve. DISCUSSION
The immediate application of these observations to clinical medicine would be to suggest the use of oxygen containing a low concentration (0005°0) of carbon monoxide during a crisis or before exposure of a sickle-cell patient to a lowered oxygen tension. In the classical picture of the crisis, any anoxia leads to sickle-cell formation, followed by an increase in blood viscosity and obstruction of blood-flow. While the oxygen tension is then dangerously reduced, the carbon monoxide attached to the haemoglobin would be unaffected. The equivalent oxygen tension would thus be increased, the degree of sickling reduced, and the obstruction due to increased blood viscosity might be alleviated. 7.
Allison,
A. C. Clin. Sci.
1956, 15,
497.
As a more general treatment it would be interesting to find out whether a low concentration of carbon monoxide could be used to reduce the anaemia. Sickle cells are more fragile mechanically than the discoidal form.3 This is thought to account for the relatively short life-span of the erythrocytes in these patients.8I If the degree of sickling is reduced, the life of the cell should be correspondingly increased. Since cigarette-smoking produces a 5% COHb concentration, this would be a simple way of maintaining the level in practice. (The patient is a non-smoker.) The danger of carbon monoxide normally is that it reduces the capacity of the erythrocyte to unload oxygen from its saturated 02Hb condition in arterial blood to the venous level. With sickle-cell haemoglobin this consideration is not so critical. Patients with Hb S disease have low arterial oxygen tensions and increased alveolar-arterial oxygen gradients. 10 The dissociation curve of Hb S is also displaced to the right.11 From an examination of ten patients Fowler et al.1o found the 02Hb arterial values varied from 80 to 92-6% of capacity, with a mean of 88-3%, compared to a normal of 96-5%. A low concentration of carbon monoxide should not therefore affect sickle-cell
patients significantly. It is obvious that
a more
detailed examination of this
approach, including a direct correlation of the proportion of COHb and degree of sickling, is necessary before any firm
be made of its value. These preliminary results were thought, however, to show sufficient promise to be of interest to others. I should like to thank Prof. P. L. Mollison for allowing me to study his patient and for the use of haematological data obtained by his unit. I
assessment can
also indebted to Dr. P. Barkhan for his assistance. Department of Physics, St. Mary’s Hospital JOHN A. SIRS Medical School, PH.D. Cantab. University of London, W.2
am
STUDIES ON NEWLY RECOGNISED STRAINS OF STAPHYLOCOCCUS AUREUS ASSOCIATED WITH HOSPITAL INFECTION RECENTLY we have attempted to determine the relation of pigment production on glycerol monoacetate 12-14 to other marker-characteristics of Staphylococcus agar aureus (coagulase-positive staphylococci). To this end, 1378 strains of the organism freshly isolated from human sources were examined. Of these, 826 were isolated, consecutively, predominantly from lesions of inpatients and outpatients at two large general hospitals in Leeds, 182 were from inpatients at a chest hospital, and 370 strains came from widely separated centres in Yorkshire. In addition, the 74, strains held by the National Collection of Type Cultures were also examined. Turner and Willis 12-14 noted that many multipleresistant staphylococci-i.e., strains that were resistant to penicillin and tetracycline at least-formed yellow, rather than orange, pigmented colonies on glycerol monoacetate agar, and they suggested that this was a potentially valuable marker characteristic. In the present study, of the 1452 strains, 670 were multiple-antibiotic-resistant, and of these 475 were the yellow variety. On the other hand, of the 782 tetra8. 9.
10. 11. 12. 13. 14.
Singer, K., Robin, S., King, J. C., Jefferson, R. N. J. Lab. clin. Med. 1948, 33, 975. Callender, S. T. E., Nickel, J. F., Moore, C. V., Powell, E. O. ibid. 1949, 34, 90. Fowler, N. O., Smith, O., Greenfield, J. C. Amer. J. med. Sci. 1957, 234, 449. Becklake, M. R., Griffiths, S. B., McGregor, M., Goldman, H. I., Schreve, J. P. J. clin. Invest. 1955, 34, 751. Willis, A. T., Turner, G. C. J. Path. Bact. 1962, 84, 337. Turner, G. C., Willis, A. T. ibid. p. 349. Willis, A. T., Turner, G. C. ibid. 1963, 85 (in the press).
Summary months, was admitted
to hospital, with due to vaccinia gangrenosa hypogammaglobutinaemia, 5 weeks after vaccination. He was treated by replacement therapy with postvaccinial gamma-globulin, by foetal lymphatic-tissue transplants, and by skin homografts.
A
boy, aged
7
N-methylisatin -thiosemicarbazone (compound 33/T/ 57) was given orally. His condition deteriorated steadily and he died 20 days after admission. The indications of hypogammaglobulinsemia are given, and exclusion of affected individuals from vaccination programmes is advised. The
treatment
grateful
of
our
patient is discussed.
am
to
Prof. J. R.
Squire,
of the
Preliminary
department
to
Communications
THE sickling phenomena of erythrocytes was first observed by Herrickin 1910. Reversion of the cell to normal discoidal form with increasing oxygen tension has been examined by Sherman2 and Harris et al.3 The present study was undertaken to establish whether other ligands-such as carbon monoxide and nitric oxidewould also reverse sickling, and to explore the possibility of reducing the degree of sickle-cell formation in vivo by a
N. Amer.
Hutchinson, J. (1879) Brit. med. J. ii, 960. Keidan, S. E., McCarthy, K., Haworth, J. C. (1953)
Arch. Dis. Childh.
7,
28,
110.
Kempe, Martin,
C. H. (1960) Pediatrics, 26, 176. C. M., Waite, J. B., McCullough, N. B. (1957)
J. clin. Invest. 36,
405.
Medical Research Council committee (1962) Lancet, i, 873.
0-2 g. sodium bicarbonate, and 0-24 g. calcium chloride per litre), and the 1 in 50 suspension was reduced in a similar manner but without any carbon dioxide. In this case the completely reduced cells at pH 8 remained perfectly discoidal, demonstrating the decrease of sickling with increasing pH.
potassium chloride,
THE USE OF CARBON MONOXIDE TO PREVENT SICKLE-CELL FORMATION
supplementing oxygen with
REFERENCES
Bauer, D. J., Sadler, P. W. (1960) Lancet, i, 1110. Bruton, O. C. (1952) Pediatrics, 9, 722. Good, E., Zak, S., Condie, R., Bridges, R. (1960) Pediat. Clin. 397.
of experiDr. J. F. Soothill, for help with gamma-globulin estimations; to Dr. H. W. Bunje for supplies of postvaccinial gamma-globulin; to Dr. D. J. Bauer of the Wellcome Institute for advice and supply of compound
I
mental pathology, Birmingham University, for his advice;
33/T/57; to Mr. D. C. Bodenham, of the Frenchay Hospital, Bristol, for supply of stored skin; and to Dr. G. H. Tovey and Dr. N. F. W. Brueton of the blood-transfusion centre, Southmead Hospital, Bristol, for their kindness in supplying the foetal tissue, and assessment of red-cell survival. I also thank Dr. G. Stewart-Smith of Exeter for postmortem studies, and his department (particularly Miss M. McCready) for plasmaprotein electrophoresis; and Dr. Brendan Moore for the virology studies and advice. I am particularly indebted to Dr. F. S. W. Brimblecombe of Exeter for permission to publish details of this case, and for his encouragement and advice throughout.
on the oxygen tension and in the percentage saturation of the cell-haemoglobin.23 A typical curve obtained with the patient’s blood is shown in the figure. The oxygen tension was slowly reduced by equilibrating
The
degree of sickling depends
turn on
low concentration of carbon
monoxide. THE PATIENT
The subject was a male West Indian, from Grenada, aged 29. The symptoms were ulcers on both legs, some blurring of vision in the left eye, and occasional attacks of epistaxis and dizziness. Otherwise the patient’s health was relatively good, and he worked as a dishwasher in a restaurant. There was no history of bone pain or abdominal pain, and no evidence of neurological disorders or jaundice. The spleen was not palpable and there was no evidence of enlargement on X-ray. Microscopical examination of a venous blood-sample revealed sickle cells, and complete sickling occurred on addition of isotonic on a starch hydrosulphite. Electrophoresis of the block, with barbiturate buffer, pH 8-6, showed 97-98% Hb S, 15%Hb A2 and less than 1% Hb F. This would suggest a homozygote for Hb S, though a combination of Hb S and thalassxmia cannot be completely excluded. No relatives were available for examination of this possibility. The haemoglobin level remained 9-10 g. per 100 ml., with persistent reticulocytosis of 8-25%.
haemoglobin
MEASUREMENTS IN VITRO
A
sample of blood, obtained by venepuncture, was slowly reduced in a tonometer by repeated flushing and shaking with a gas mixture of oxygen-free nitrogen and 50 mm. Hg partial pressure of carbon dioxide. Microscopical examination revealed 100% sickling. Three samples of the reduced cells were then taken and separately with oxygen, carbon monoxide, and nitric oxide, air being excluded. In all three cases the sickle cells reverted to the discoidal form. In another experiment 10 ml. of whole blood was added to 490 ml. of RingerLocke solution (composition 9 g. sodium chloride, 0-42 g.
saturated
1 Herrick, J. B. Arch. intern. Med. 1910, 6, 517. 2. Sherman, I. J. Bull. Johns Hopk. Hosp. 1940, 67, 309. 3. Harris, J. W., Brewster, H. H., Ham, T. H., Castle, W. B. Arch. intern. Med. 1956, 97, 145.
Partial pressure oF oxygen A
(mm.Hg)
showing the relation between the percentage of sickle cells and partial pressure of oxygen obtained with the patient’s blood. curve
the whole blood in a tonometer at 37°C with known mixtures of air and nitrogen while maintaining a constant partial pressure of 50 mm. Hg of carbon dioxide. Samples of the blood were taken, avoiding contact with air, and fixed in a solution of 0-85 g. of sodium chloride in 100 ml. of 10% formaldehyde. The percentage of sickle cells was then ascertained by counting, on a wet-slide preparation, under a microscope. The reversibility of sickle cells when saturated with carbon monoxide suggested that the degree of sickling would depend on the proportion of carbon-monoxide haemoglobin (COHb), in a similar manner to that of oxygen (see figure). If carbon monoxide and oxygen are used together the combined effect could be calculated by using the Haldane principles5 in the presence of a low concentration of carbon monoxide, of the order 0-0050-01%, a proportion of the haemoglobin (5-10%) is converted to COHb. Because of the slow dissociation of COHb (a half-life of 250 minutes has recently been estimated by Roughton 6), this is not significantly changed as the blood flows through regions of low oxygen tension in the venous system. The 4. 5.
Douglas, C. G., Haldane,J. S., Haldane, J. B. S. J.Physiol. 1912, 44, 275. Roughton, F. J. W. The Regulation of Human Respiration (J. S. Haldane Centenary Symposium); p. 33. Oxford, 1963.
6. Roughton, F. T. W. Brit. med. Bull. 1963, 19, 80.
972
however, behaves as if the dissociation curve had been the left, combining and dissociating freely with the haemoglobin not immobilised by carbon monoxide. If for example the venous oxygen tension fell to 30 mm. Hg pp., the corresponding degree of oxyhasmoglobin (02Hb) saturation would be 40%. If 5%COHb is present, the effective XHb (i.e., COHb and 02Hb) saturation with 30 mm. Hg pp. of
oxygen,
shifted
to
oxygen is raised to 56%. The percentage of sickle cells should thus be correspondingly reduced in the presence of COHb. To test this possibility a sample of blood was equilibrated in a tonometer at 37°C by shaking and flushing with a mixture of air, nitrogen, and carbon dioxide, corresponding approximately to a mean arterial-venous environment. An examination of the cells showed, as would be expected from the figure, an incidence of 19-5% sickle cells. The same cells were then equilibrated with the above gas mixture containing in addition 0-08 mm. pp. Hg of carbon monoxide. Upon fixing in formaldehyde solution and re-examining the cells, only 6% sickle cells were present. This is consistent with having added an equivalent partial pressure of oxygen along the abscissa of the figure. MEASUREMENTS
IN
VIVO
The next stage of the observations was to examine if the reduction of sickling after adding a low concentration of carbon monoxide could be obtained in vivo. A mask was fitted over the mouth and nose of the patient so that air was breathed from a closed-circuit Benedict spirometer. Oxygen was supplied to the bell at a rate sufficient to maintain the recorder pen at a steady level (approximately 200 ml. per minute). After allowing several minutes for the patient to settle down and for his breathing to become regular, a blood-sample was taken by venepuncture. This was quickly transferred to the formaldehyde fixing solution. Carbon monoxide was then injected slowly into the plastic tubing supplying oxygen to the bell, over a period of thirty minutes, using a 50 ml. syringe and needle. A total of 25 ml. of carbon monoxide was admitted, corresponding to an estimated 4% saturation of COHb in the red cells. The mask was removed, and the patient was allowed to breathe atmospheric air for several minutes. A second blood-sample was then taken by venepuncture and fixed in formaldehyde solution. Microscopical examination disclosed an initial concentration of 10-2% sickle cells with a standard deviation of ±2-5%, and only 3’9±1’5% sickle cells after the addition of carbon monoxide (P < 0-05). An unusual aspect of these measurements is the relatively low number of sickle cells observed initially. Sherman2 has reported sixteen tests on eleven patients with sickle-cell anaemia, with the degree of venous sickling between 30% and 60%. In the present measurements no particular precautions were taken to exclude air, since both samples would be similarly exposed, and any change to normal form takes at least two minutes,the venepuncture and transfer to the formaldehyde solution being completed well within this interval. This point would require further examination, but if a change did occur during this procedure the error would be to minimise any difference between the samples, and so the figures quoted would represent the minimum benefit a small concentration of carbon monoxide would achieve. DISCUSSION
The immediate application of these observations to clinical medicine would be to suggest the use of oxygen containing a low concentration (0005°0) of carbon monoxide during a crisis or before exposure of a sickle-cell patient to a lowered oxygen tension. In the classical picture of the crisis, any anoxia leads to sickle-cell formation, followed by an increase in blood viscosity and obstruction of blood-flow. While the oxygen tension is then dangerously reduced, the carbon monoxide attached to the haemoglobin would be unaffected. The equivalent oxygen tension would thus be increased, the degree of sickling reduced, and the obstruction due to increased blood viscosity might be alleviated. 7.
Allison,
A. C. Clin. Sci.
1956, 15,
497.
As a more general treatment it would be interesting to find out whether a low concentration of carbon monoxide could be used to reduce the anaemia. Sickle cells are more fragile mechanically than the discoidal form.3 This is thought to account for the relatively short life-span of the erythrocytes in these patients.8I If the degree of sickling is reduced, the life of the cell should be correspondingly increased. Since cigarette-smoking produces a 5% COHb concentration, this would be a simple way of maintaining the level in practice. (The patient is a non-smoker.) The danger of carbon monoxide normally is that it reduces the capacity of the erythrocyte to unload oxygen from its saturated 02Hb condition in arterial blood to the venous level. With sickle-cell haemoglobin this consideration is not so critical. Patients with Hb S disease have low arterial oxygen tensions and increased alveolar-arterial oxygen gradients. 10 The dissociation curve of Hb S is also displaced to the right.11 From an examination of ten patients Fowler et al.1o found the 02Hb arterial values varied from 80 to 92-6% of capacity, with a mean of 88-3%, compared to a normal of 96-5%. A low concentration of carbon monoxide should not therefore affect sickle-cell
patients significantly. It is obvious that
a more
detailed examination of this
approach, including a direct correlation of the proportion of COHb and degree of sickling, is necessary before any firm
be made of its value. These preliminary results were thought, however, to show sufficient promise to be of interest to others. I should like to thank Prof. P. L. Mollison for allowing me to study his patient and for the use of haematological data obtained by his unit. I
assessment can
also indebted to Dr. P. Barkhan for his assistance. Department of Physics, St. Mary’s Hospital JOHN A. SIRS Medical School, PH.D. Cantab. University of London, W.2
am
STUDIES ON NEWLY RECOGNISED STRAINS OF STAPHYLOCOCCUS AUREUS ASSOCIATED WITH HOSPITAL INFECTION RECENTLY we have attempted to determine the relation of pigment production on glycerol monoacetate 12-14 to other marker-characteristics of Staphylococcus agar aureus (coagulase-positive staphylococci). To this end, 1378 strains of the organism freshly isolated from human sources were examined. Of these, 826 were isolated, consecutively, predominantly from lesions of inpatients and outpatients at two large general hospitals in Leeds, 182 were from inpatients at a chest hospital, and 370 strains came from widely separated centres in Yorkshire. In addition, the 74, strains held by the National Collection of Type Cultures were also examined. Turner and Willis 12-14 noted that many multipleresistant staphylococci-i.e., strains that were resistant to penicillin and tetracycline at least-formed yellow, rather than orange, pigmented colonies on glycerol monoacetate agar, and they suggested that this was a potentially valuable marker characteristic. In the present study, of the 1452 strains, 670 were multiple-antibiotic-resistant, and of these 475 were the yellow variety. On the other hand, of the 782 tetra8. 9.
10. 11. 12. 13. 14.
Singer, K., Robin, S., King, J. C., Jefferson, R. N. J. Lab. clin. Med. 1948, 33, 975. Callender, S. T. E., Nickel, J. F., Moore, C. V., Powell, E. O. ibid. 1949, 34, 90. Fowler, N. O., Smith, O., Greenfield, J. C. Amer. J. med. Sci. 1957, 234, 449. Becklake, M. R., Griffiths, S. B., McGregor, M., Goldman, H. I., Schreve, J. P. J. clin. Invest. 1955, 34, 751. Willis, A. T., Turner, G. C. J. Path. Bact. 1962, 84, 337. Turner, G. C., Willis, A. T. ibid. p. 349. Willis, A. T., Turner, G. C. ibid. 1963, 85 (in the press).