- Email: [email protected]
CREAM
802 of the previous description of this type of device. We made no claim to originality, however, and, further, the description in the textbook to which Dr. Hobbs refers is only very brief. We would again stress the value of this type of device in the operating-theatre, where the level and tilt of the table are frequently altered."-ED.L.
we were unaware
DEXTRAN 40
SIR,-Prompted by your annotation on the new B.P. Addendum,1 we should like to comment on the monographs on dextran with special reference to the one on dextran 40, a product which was originally developed and characterised, and the use of which was pioneered, by our company under the of ’Rheomacrodex ’. We very much regret the inclusion of dextran 40 in the 1966 Addendum based on the monograph as it now stands, because we consider the methods given for its characterisation to be insufficient, and conducive to erroneous and misleading information on the factual average molecular weight and molecular-weight distribution in a given preparation. The determination of intrinsic viscosity, which the monograph prescribes as the only procedure for characterisation of molecular size, is an indirect method, and must depend on calibrated standards relating the viscosity to molecular size determined by an absolute method such as the light-scattering
name
analysis. It is our experience, based on a vast amount of determinations of samples from various sources, that there exists no satisfactory general correlation between viscosity and molecular size for the dextran fractions in clinical use. Substantial variations in both average molecular size and size of the important tail-end fractions can exist for samples well within the viscosity limits given in the B.P. specification. Accordingly a prescribing physician cannot be sure that a preparation of dextran 40, characterised only by the monograph in the B.P., is in fact identical with one with which he has previously obtained the biological effect and the absence of side-reactions which led him to use the treatment in the first place. It should be pointed out that the light-scattering method is by no means an esoteric novelty, since it is the procedure used to secure that dextran preparations correspond to the U.S. Defence Medical Purchase Description, a set of specifications which have gradually gained acceptance as an international standard. In addition, with regard to other indices, the new B.P. monograph fails to include up-to-date, adequate, and exhaustive methods now available for the characterisation of the relatively complex, polydisperse mixtures of polymers known as dextrans. ADOLF BERGGREN Research Division, Pharmacia AB, KIRSTI GRANATH. Uppsala, Sweden.
CREAM
SIR,-Your annotation (Sept. 10, p. 580) and the report2 on fresh cream in Worcestershire are timely. Colenso et al. are to be congratulated on an interesting and valuable survey. As you rightly point out, too little attention has been paid in the past to cream and its bacteriological quality. In addition to the well-knowa West Country clotted creams, a confusing variety of different liquid creams are available, and there is a tendency to assume that because most of these are heat-treated or pasteurised, all is well. This is not borne out by our experience, which corresponds generally with that described in Worcestershire; our findings will be published when our
investigations
are
completed.
We have now examined more than 500 samples of various creams, and although we have some reservations about the phosphatase test, we consider that the methylene-blue1. 2.
Lancet, 1966, i, 867. Colenso, R., Court, G., Henderson, 25, 153.
R.
J. Mon. Bull. Min. Hlth, 1966,
reduction test together with a semiquantitative coliform test are useful. Indeed only 99 samples (22%) of clotted creams were considered to be satisfactory in that they did not decolorise methylene blue in less than 21/2 hours and were free from fxcal coli. Of over 100 samples of heat-treated fresh liquid creams examined, 44% contained fxcal coli, and most of these decolorised methylene blue in less than 30 minutes. In addition, we have isolated Brucella abortus from one cream cake, 11 samples of heat-treated liquid creams, and 4 samples of clotted creams. Contamination after heat-treatment and bulk distribution will always remain potential hazards, but our findings suggest that there is still some room for improvement in creamprocessing methods, and support the view that there should be a minimum bacteriological standard in order to give the consumer a reasonable degree of protection. Public Health Laboratory, Royal Cornwall Hospital (City), Truro, Cornwall. Health Area Office, Penzance, Cornwall.
G. I. BARROW D. C. MILLER. D. L. JOHNSON.
Yy CHROMOSOMAL CHIMÆRISM SIR,-We have read with interest the letter of Dr. Naiman and his colleagues (Sept. 10, p. 590) in which they report an apparent foetal graft arising after intrauterine bloodtransfusion for erythroblastosis foetalis. In 1962 we published1 results demonstrating the persistence of viable, mitoticallycompetent, lymphocytes in bank blood, and discussed the implications which lymphocyte grafts might have under specific clinical situations. We suggested that consideration should be given to the removal of leucocytes from blood to be administered to patients with incompetent immune mechanisms. The report of Dr. Naiman and his colleagues, in which they advance the finding of " Yy " chromosomal chimxrism as evidence for such a graft, may represent the first firm evidence for lymphocyte graft arising from blood-tranfusion. We await with interest their detailed report. Department of Epidemiology and Preventive Medicine, University of California, San Francisco Medical Center.
NICHOLAS L. PETRAKIS.
MITOGENIC ACTION OF PAPAIN SIR,-We have found (July 23, p. 232) that trypsin and chymotrypsin have a mitogenic action on in-vitro short-term cultures of peripheral lymphocytes from normal persons. Such an effect seems to be related to the damaging action of these enzymes on the cell membrane. This finding supports the hypothesis that the mitogenic action of phytohaemagglutinin (P.H.A.) on lymphocytes from almost all normal persons is also non-specific, and depends on an irritative or damaging action on the cell surface, unrelated to immunological mechanisms. We report here analogous results with papain to those we have obtained with trypsin and chymotrypsin. Cultures of lymphocytes incubated with papain showed higher incidence of blastic elements than controls. Lymphocytes from 5 normal persons were tested: at the 144th hour, in the cultures with papain, blastic elements ranged from 2 to 7% of cultured cells, while in control cultures without stimulating agents they ranged from 0-03 to 0-1%. But papain, at the concentration used (8-40 g. per 5 ml. of medium), showed a weaker mitogenic action than trypsin and chymotrypsin (2-14% of blastic elements at the 96th hour), and than all the other blastogenic substances with a non-specific action, such as P.H.A.,2 staphylococcal haemolysins,3 and anti-leucocyte sera.’ The demonstration of the mitogenic action of another proteolytic enzyme, in addition to trypsin and chymotrypsin, 1. 2. 3. 4.
Petrakis, N. L., Politis, G. New Engl. J. Med. 1962, 267, 286. Nowell, P. C. Cancer Res. 1960, 20, 462. Ling, N. R., Husband, E. M. Lancet, 1964, i, 363. Grasbeck, R., Nordman, C., de la Chapelle, A. ibid. 1963, ii,
385.
we were unaware
DEXTRAN 40
SIR,-Prompted by your annotation on the new B.P. Addendum,1 we should like to comment on the monographs on dextran with special reference to the one on dextran 40, a product which was originally developed and characterised, and the use of which was pioneered, by our company under the of ’Rheomacrodex ’. We very much regret the inclusion of dextran 40 in the 1966 Addendum based on the monograph as it now stands, because we consider the methods given for its characterisation to be insufficient, and conducive to erroneous and misleading information on the factual average molecular weight and molecular-weight distribution in a given preparation. The determination of intrinsic viscosity, which the monograph prescribes as the only procedure for characterisation of molecular size, is an indirect method, and must depend on calibrated standards relating the viscosity to molecular size determined by an absolute method such as the light-scattering
name
analysis. It is our experience, based on a vast amount of determinations of samples from various sources, that there exists no satisfactory general correlation between viscosity and molecular size for the dextran fractions in clinical use. Substantial variations in both average molecular size and size of the important tail-end fractions can exist for samples well within the viscosity limits given in the B.P. specification. Accordingly a prescribing physician cannot be sure that a preparation of dextran 40, characterised only by the monograph in the B.P., is in fact identical with one with which he has previously obtained the biological effect and the absence of side-reactions which led him to use the treatment in the first place. It should be pointed out that the light-scattering method is by no means an esoteric novelty, since it is the procedure used to secure that dextran preparations correspond to the U.S. Defence Medical Purchase Description, a set of specifications which have gradually gained acceptance as an international standard. In addition, with regard to other indices, the new B.P. monograph fails to include up-to-date, adequate, and exhaustive methods now available for the characterisation of the relatively complex, polydisperse mixtures of polymers known as dextrans. ADOLF BERGGREN Research Division, Pharmacia AB, KIRSTI GRANATH. Uppsala, Sweden.
CREAM
SIR,-Your annotation (Sept. 10, p. 580) and the report2 on fresh cream in Worcestershire are timely. Colenso et al. are to be congratulated on an interesting and valuable survey. As you rightly point out, too little attention has been paid in the past to cream and its bacteriological quality. In addition to the well-knowa West Country clotted creams, a confusing variety of different liquid creams are available, and there is a tendency to assume that because most of these are heat-treated or pasteurised, all is well. This is not borne out by our experience, which corresponds generally with that described in Worcestershire; our findings will be published when our
investigations
are
completed.
We have now examined more than 500 samples of various creams, and although we have some reservations about the phosphatase test, we consider that the methylene-blue1. 2.
Lancet, 1966, i, 867. Colenso, R., Court, G., Henderson, 25, 153.
R.
J. Mon. Bull. Min. Hlth, 1966,
reduction test together with a semiquantitative coliform test are useful. Indeed only 99 samples (22%) of clotted creams were considered to be satisfactory in that they did not decolorise methylene blue in less than 21/2 hours and were free from fxcal coli. Of over 100 samples of heat-treated fresh liquid creams examined, 44% contained fxcal coli, and most of these decolorised methylene blue in less than 30 minutes. In addition, we have isolated Brucella abortus from one cream cake, 11 samples of heat-treated liquid creams, and 4 samples of clotted creams. Contamination after heat-treatment and bulk distribution will always remain potential hazards, but our findings suggest that there is still some room for improvement in creamprocessing methods, and support the view that there should be a minimum bacteriological standard in order to give the consumer a reasonable degree of protection. Public Health Laboratory, Royal Cornwall Hospital (City), Truro, Cornwall. Health Area Office, Penzance, Cornwall.
G. I. BARROW D. C. MILLER. D. L. JOHNSON.
Yy CHROMOSOMAL CHIMÆRISM SIR,-We have read with interest the letter of Dr. Naiman and his colleagues (Sept. 10, p. 590) in which they report an apparent foetal graft arising after intrauterine bloodtransfusion for erythroblastosis foetalis. In 1962 we published1 results demonstrating the persistence of viable, mitoticallycompetent, lymphocytes in bank blood, and discussed the implications which lymphocyte grafts might have under specific clinical situations. We suggested that consideration should be given to the removal of leucocytes from blood to be administered to patients with incompetent immune mechanisms. The report of Dr. Naiman and his colleagues, in which they advance the finding of " Yy " chromosomal chimxrism as evidence for such a graft, may represent the first firm evidence for lymphocyte graft arising from blood-tranfusion. We await with interest their detailed report. Department of Epidemiology and Preventive Medicine, University of California, San Francisco Medical Center.
NICHOLAS L. PETRAKIS.
MITOGENIC ACTION OF PAPAIN SIR,-We have found (July 23, p. 232) that trypsin and chymotrypsin have a mitogenic action on in-vitro short-term cultures of peripheral lymphocytes from normal persons. Such an effect seems to be related to the damaging action of these enzymes on the cell membrane. This finding supports the hypothesis that the mitogenic action of phytohaemagglutinin (P.H.A.) on lymphocytes from almost all normal persons is also non-specific, and depends on an irritative or damaging action on the cell surface, unrelated to immunological mechanisms. We report here analogous results with papain to those we have obtained with trypsin and chymotrypsin. Cultures of lymphocytes incubated with papain showed higher incidence of blastic elements than controls. Lymphocytes from 5 normal persons were tested: at the 144th hour, in the cultures with papain, blastic elements ranged from 2 to 7% of cultured cells, while in control cultures without stimulating agents they ranged from 0-03 to 0-1%. But papain, at the concentration used (8-40 g. per 5 ml. of medium), showed a weaker mitogenic action than trypsin and chymotrypsin (2-14% of blastic elements at the 96th hour), and than all the other blastogenic substances with a non-specific action, such as P.H.A.,2 staphylococcal haemolysins,3 and anti-leucocyte sera.’ The demonstration of the mitogenic action of another proteolytic enzyme, in addition to trypsin and chymotrypsin, 1. 2. 3. 4.
Petrakis, N. L., Politis, G. New Engl. J. Med. 1962, 267, 286. Nowell, P. C. Cancer Res. 1960, 20, 462. Ling, N. R., Husband, E. M. Lancet, 1964, i, 363. Grasbeck, R., Nordman, C., de la Chapelle, A. ibid. 1963, ii,
385.