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CHROMOSOME ANALYSIS OF HUMAN AMNIOTIC-FLUID CELLS
1210 in the whole animal. Thus under basal conditions and after cortisol induction, allopurinol does not exert any effect in vivo, and this would lead to the conclusion that the drug given alone may not be effective (as an antidcpressant) particularly in those patients with high circulating corticostcroids and a raised tryptophan pyrrolasc activity. We suggestedthat allopurinol should be given together with tryptophan for two reasons. Firstly, the tryptophan activation of the pyrrolase (as measured in vitro) is prevented by pretreatment of rats with allopurinol/ a finding which is consistent with, and supported by, that dcmonstrating a further increase in brain tryptophan caused by allopurinol in rats treated with the aminoacid.’ Secondly, since tryptophan acts on the pyrrolase in vivo by activating the pre-existing apoenzymeallopurinol blocks this by preventing the conjugation of the apoenzyme. Thus allopurinol given in combination with the aminoacid could exert the desired effect on tryptophan pyrrolase activity and on brain tryptophan and serotonin. In discussing the role of nicotinamidc, it must be pointed out that it actually enhances (rather than inhibits) tryptophan pyrrolase activity in the intact rat.The doses used are 50 mg. per kg. for the in-vivo and 500 mg. per kg. for the in-vitro assay. The latter dose (which is equivalent to 35 g. given to a 70 kg. patient) causes inhibition only in hypophysectomised (and also adrenalectomised) rats which were presumably used to avoid the non-specific induction observed in the normal intact animal. Hypophysectomised rats have a higher basal pyrrolase activity " which is not even decreased by nicotinamide to values of intact animals. Another point of doubt (in the context of the present discussion) is that hypophysectomised rats (showing pyrrolase inhibition by nicotinamide) are maintained on 5"., glucose, a treatment known to inhibit the pyrrolase activity.’’ The suppression (measured in vitro) of the tryptophan activation of the enzyme by nicotinamidc, 1 to which Young and Sourkes refer, is achieved in adrenalectomised rats by a dose of at least 200 mg. of nicotinamide per kg. body-weight (or 14 g. per adult man), and is suggested to be due to inhibition of tryptophan pyrrolase synthesis at the translation step, yet another inhibitor of translation, cycloheximide, prevents the tryptophan activation of the " enzyme which does not involve increased synthesis. The value of nicotinamide in partially preventing the excessive urinary excretion ’of hepatic tryptophan metabolites 12may be linked to its ability to activate certain N.A.D.I -dependent enzymes along the pathway rather than by inhibiting tryptophan pyrrolase activity. The possibility that nicotinamide may inhibit the pyrrolase by being converted into N.A.D.n. and/or N.A.D.P.H., both of which are allosteric inhibitors,’3 is also not clearly understood. It is not known how much of the N.A.D. and N.A.D.P.-’ formed from nicotinamide are converted into their reduced forms which are the effective pyrrolase inhibitors, but studies with administered tryptophan " show the following: (1) liver N.A.D. and the sum of N.A.D. 1 1 N.A.D.H. increase in proportion to the dietary dose of tryptophan, (2) evening N.A.D.11. (inhibitor) is lower than morning values, (3) the ratio of N.A.D. /I N.A.D.H. increases (rather than decreases) in proportion to the dose of tryptophan, and evening ratios are even higher than morning ones. In other studies it was found that tryptophan increases the liver N.A.D.H. much less than 7. 8. 9. 10. 11. 12. 13. 14. 15.
Schimke, R. T. Curr. Top. Cell. Regul. 1969, 1, 77. Yamaguchi, K., Shimoyama, M., Gholson, R. K. Brochum. biophys. Acta. 1967, 146, 102. Yuwiler, A., Wetterberg, L., Geller, E. ibid. 1970, 208, 428. Cho-Chung, Y. S., Pitot, H. C. Eur. J. Biochem. 1968, 3, 401. Badawy, A. A.-B., Smith, M. J. H. Biochem. J. 1971, 123, 171. Muggeo, M., De Antoni, A., Allegri, G., Costa, C., Crepaldi, G. Clin. chim. Acta, 1970, 30, 779. Cho-Chung, Y. S., Pitot, H. C.J. biol. Chem. 1967, 242, 1192. Powanda, M. C., Wannemacher, R. W., Jr. J. Nutr. 1970, 100, 1471. Powanda, M C., Wannemacher, R. W., Jr. Brochum. biophys. Acta, 1971, 252, 239.
N.A.D.
concentration,
increases the N.A.D.’!N.A,D.11. rdt:.j
and docs not alter the N.A.D.p.’/N.A.D.P.n. ratio. Decrease in the ratios of these redox couples have been shown to bê associated with inhibited tryptophan pyrrolase activity in livers of rats chronically treated with ethanol, phenobarbitone or morphine.16 In this context (particularly with cthanol), it should be borne in mind that a disturbance in these ratios (either way) could disturb a number oi physiological functions in the liver, and possibly in other tissues. It appears therefore that allopurinol may be useful in the treatment of depression when combined with tryptophan, but the role of nicotinamidc is lcss clear. However, whichever drug is used with tryptophan, it must be remembered that excessive production of serotonin may occur. Thts may very well relieve the depression, and we favour thh method of treatment in principle, but it may also cause unknown and possibly unwelcome effects. The clinician should therefore approach this method of treatment with caution. If combined with allopurinol (or any other pyrrolasc inhibitor), tryptophan should be given in smaller doses under careful clinical supervision and the patientB condition watched closely. Addiction Unit Research Laboratory, Whitchurch Hospital, Whitchurch, Cardiff CF47XB.
A. A.-B. BADAWY M. EVANS.
CHROMOSOME ANALYSIS OF HUMAN AMNIOTIC-FLUID CELLS
SIR,—Contrary to the assertion of Dr Laurence (Oct. 19, p. 939), H. P. Klinger was not the first to culture and karyotypc fctal amniotic-fluid cells; and W. Roy Breg and I most certainly were not merely Klinger’s Boswell.1 The facts are these. Dr Breg and I, working together, successfully cultured and karyotyped fetal amniotic-fluid cells between about November, 1964, through August, 1965; and we reported these results in November, 1965, in a paper presented to the Fourth Conference on Mammalian Cytology and Somatic Cell Genetics in Williamsburg, Virginia. In the discussion following our presentation, Dr Klinger brought forth his own data; and that was the first we knew of his efforts in this area. Since Klinger’s work confirmed ours, we referred to it in our formal publication in 7he Lancet of Feb. 19, 1966. To my knowledge, Klinger never did publish his own work on this. By 1965 chromosome analysis of human amniotic-fluid cells " was an idea whose time had come. That Klinger on the one hand and Breg and I on the other independently achieved this first was simply serendipity. Department of Pediatrics, Children’s Hospital of Pittsburgh, 125 DeSoto
Street,
Pittsburgh, Pennsylvania 15213, U.S.A.
MARK W. STEELE.
DOWN WITH PARAMETERS
SIR,—I agree with Dr Cooke (Nov. 2, p. 1090) that th word " parameter " is misused with irritating frequency. It is a word that I eschew as much as possible, and would claim that my lectures and papers have been completed without it. A simpler definition than those given by Dr Cooke would be that it is a measurement which change with another measurement: all the examples that he gives comply with this. Because of the imperfect state of medical measurement. therefore, this word still has a use. For example, we have no measure of cerebral blood-flow, but the results yielded 16. 17.
Badawy, A. A.-B., Evans, M. Advanc. exp. Med Biol. in the Steele, M. W., Breg, W. R., Jr. Lancet, 1966, 1, 383.
p
Schimke, R. T. Curr. Top. Cell. Regul. 1969, 1, 77. Yamaguchi, K., Shimoyama, M., Gholson, R. K. Brochum. biophys. Acta. 1967, 146, 102. Yuwiler, A., Wetterberg, L., Geller, E. ibid. 1970, 208, 428. Cho-Chung, Y. S., Pitot, H. C. Eur. J. Biochem. 1968, 3, 401. Badawy, A. A.-B., Smith, M. J. H. Biochem. J. 1971, 123, 171. Muggeo, M., De Antoni, A., Allegri, G., Costa, C., Crepaldi, G. Clin. chim. Acta, 1970, 30, 779. Cho-Chung, Y. S., Pitot, H. C.J. biol. Chem. 1967, 242, 1192. Powanda, M. C., Wannemacher, R. W., Jr. J. Nutr. 1970, 100, 1471. Powanda, M C., Wannemacher, R. W., Jr. Brochum. biophys. Acta, 1971, 252, 239.
N.A.D.
concentration,
increases the N.A.D.’!N.A,D.11. rdt:.j
and docs not alter the N.A.D.p.’/N.A.D.P.n. ratio. Decrease in the ratios of these redox couples have been shown to bê associated with inhibited tryptophan pyrrolase activity in livers of rats chronically treated with ethanol, phenobarbitone or morphine.16 In this context (particularly with cthanol), it should be borne in mind that a disturbance in these ratios (either way) could disturb a number oi physiological functions in the liver, and possibly in other tissues. It appears therefore that allopurinol may be useful in the treatment of depression when combined with tryptophan, but the role of nicotinamidc is lcss clear. However, whichever drug is used with tryptophan, it must be remembered that excessive production of serotonin may occur. Thts may very well relieve the depression, and we favour thh method of treatment in principle, but it may also cause unknown and possibly unwelcome effects. The clinician should therefore approach this method of treatment with caution. If combined with allopurinol (or any other pyrrolasc inhibitor), tryptophan should be given in smaller doses under careful clinical supervision and the patientB condition watched closely. Addiction Unit Research Laboratory, Whitchurch Hospital, Whitchurch, Cardiff CF47XB.
A. A.-B. BADAWY M. EVANS.
CHROMOSOME ANALYSIS OF HUMAN AMNIOTIC-FLUID CELLS
SIR,—Contrary to the assertion of Dr Laurence (Oct. 19, p. 939), H. P. Klinger was not the first to culture and karyotypc fctal amniotic-fluid cells; and W. Roy Breg and I most certainly were not merely Klinger’s Boswell.1 The facts are these. Dr Breg and I, working together, successfully cultured and karyotyped fetal amniotic-fluid cells between about November, 1964, through August, 1965; and we reported these results in November, 1965, in a paper presented to the Fourth Conference on Mammalian Cytology and Somatic Cell Genetics in Williamsburg, Virginia. In the discussion following our presentation, Dr Klinger brought forth his own data; and that was the first we knew of his efforts in this area. Since Klinger’s work confirmed ours, we referred to it in our formal publication in 7he Lancet of Feb. 19, 1966. To my knowledge, Klinger never did publish his own work on this. By 1965 chromosome analysis of human amniotic-fluid cells " was an idea whose time had come. That Klinger on the one hand and Breg and I on the other independently achieved this first was simply serendipity. Department of Pediatrics, Children’s Hospital of Pittsburgh, 125 DeSoto
Street,
Pittsburgh, Pennsylvania 15213, U.S.A.
MARK W. STEELE.
DOWN WITH PARAMETERS
SIR,—I agree with Dr Cooke (Nov. 2, p. 1090) that th word " parameter " is misused with irritating frequency. It is a word that I eschew as much as possible, and would claim that my lectures and papers have been completed without it. A simpler definition than those given by Dr Cooke would be that it is a measurement which change with another measurement: all the examples that he gives comply with this. Because of the imperfect state of medical measurement. therefore, this word still has a use. For example, we have no measure of cerebral blood-flow, but the results yielded 16. 17.
Badawy, A. A.-B., Evans, M. Advanc. exp. Med Biol. in the Steele, M. W., Breg, W. R., Jr. Lancet, 1966, 1, 383.
p