- Email: [email protected]
EFFECT OF PHOTOTHERAPY ON SISTER CHROMATID EXCHANGE IN PREMATURE INFANTS
157
responsiveness scalean improved, less cumbersome, and more practical instrument for coma measurement than others. All patients were grade 3, 4, or 5 on the scale. They ranged in age from 4 to 80 years (mean 22). Coma was secondary to head injury in ten patients, hypoxia in four, and brain tumour, with prolonged postoperative unconsciousness, in two. All coma or
diagnoses were supported by angiography and/or computerised tomographic scanning. Patients with traumatic, acute epidural, subdural, or intracerebral hxmorrhage were excluded from the series. The first neurological examinations were done within 6 h of onset of coma and repeated daily. I.A.H.P. environmental enrichment programmes were started 12-24 h after admission to hospital, except in the two postoperative brain-tumour patients whose programmes started 10 and 14 days after surgery. Follow-up has ranged from several days to 10 months. There have been no deaths. All sixteen patients have fully recovered -from coma. Of twelve patients who have regained functional independence and are home, eight have reaquired their premorbid condition and have no detectable deficit. The other four, although still displaying some focal physical deficit or adaptive behaviour disorder, are recovering progressively. One patient, more recently admitted, is still in hospital. Two others, though alert, are in other institutions because of severe physical handicaps and lack of family to care for them. Of a comparable group of fourteen consecutive patients, also in severe coma (all grade 3-5 on the Glasgow scale), admitted to hospital during the previous 12-month period and followed up by one of us (M.D.D.), but not given programmes of environmental enrichment, eleven died (79%). The improved outcome in the I.A.H.P.-managed warrants continuation of this study.
EFFECT OF PHOTOTHERAPY ON SISTER CHROMATID EXCHANGE IN PREMATURE INFANTS first described in 1958,1 is now the method for reducing serum-bilirubin levels in jaundiced infants. Few clinically adverse side-effects directly due to phototherapy have been reported.2,3However, photosensitised damage of nucleic acids and proteins has been described in a number of biological systems.4 While no mutagenic effects of phototherapy have been detected on conventional chromosome analysis,5 Goyanes-Villaescusa et a1.6 concluded that phototherapy does increase the frequency of sister chromatid exchange (S.C.E.) in human lymphocyte chromosomes. s.c.E. induction, simply detected by bromodeoxyuridine-dye techniques,’8 is, in turn, considered to be a sensitive index of mutagen-carcinogeti exposure.8-1O However, s.c.E. analyses in our laboratory do not support the contention that phototherapy or in-vitro exposure of cells to bilirubin plus
SIR,-Phototherapy,
most common
light significantly
increase
lymphocyte
frequencies."
s.c.E.
TABLE I-EFFECT OF PHOTOTHERAPY ON S.C.E. LYMPHOCYTES FROM PREMATURE INFANTS
FREQUENCIES
IN
(S.C.E./CELL)
This letter condenses two papers-The Child in Coma (E.B.L.) and Coma recovery (M.D.D.)-presented to the llth annual meeting of the World Organisation for Human Potential, cosponsored by the National Aeronautics and Space Administration/Ames Research Center and the Institutes for the Achievement of Human Potential, at Moffett Field, California, on May 18,1978. Institutes for the Achievement
of Human Potential,
Philadelphia, Pennsylvania 19118,
U.S.A.
Neurological Surgery and Neurology, Freeport, N.Y.
EDWARD B. LEWINN
MIHAI D.
DIMANCESCU
* 29-35weeks of gestation. t Mean+ s.E.M. (and no. of cells). t Mean+ s.E. of the individual sample means. § Post-treatment values.
PROSTAGLANDIN-SYNTHESIS INHIBITORS IN PROPHYLAXIS OF FOOD INTOLERANCE
SiR,—I have had total lactose intolerance for the past twenty years. After reading the article by Dr Buisseret and his colleagues,’ I took 975 mg aspirin followed, twenty minutes later, by a heavy dairy meal consisting of a pint of ice cream, two glasses of milk, half a pound of Swiss cheese, and two ounces of butter. There were none of the customary immediate or delayed symptoms of malabsorption (borborygmi, cramps,
diarrhoea, tenesmus). The next test again followed 975 mg aspirin, and consisted of two large slices of chocolate cheese cake. Again I was free of retaliatory symptoms. I have subsequently conducted over twenty challenges, all with favourable results. My experience supports the success of Buisseret et al. with, among others, a lactose malabsorber in whom aspirin prevented symptoms after ingestion of 100 ml of cream. Department of Psychiatry, School of Medicine, Yale University, New
Haven, Connecticut 06510, U.S.A.
6. Jennett, B., Teasdale, G. Lancet, 1977, i, 878. 1. Buisseret, P. D., Youlten, L. J. F., Heinzelmann, D. I.,
1978, i, 906.
JULIAN LIEB Lessof,
F. H. Lancet,
Fifteen infants 880-1950 g, less than 58 h old, with bilirubin levels of 3-10 mg/dl, and not critically ill-were selected at random on admission to the neonatal intensive-care unit at the Boston Hospital for Women. 1 ml peripheral blood was obtained before and after 24-48 h of continuous phototherapy in a ’Narco Isolette’ phototherapy unit (Narco Medical Co.,
Warminister, Pennsylvania) containing
8
new
’Sylvania Day-
light’ bulbs (F20T12-D) set 24 cm above the infant. The incidental light energy from this apparatus, measured by chemical actinometry12 was approximately 600 W;cm2, calculated for a wavelength of 490 nm. Two blood-samples 24-48 h apart were obtained from control infants (not undergoing phototherCremer, R. J., Perryman, P. W., Richards, D. H., Lancet, 1958, i, 1094. Behrman, R. E., and others, J. Pediat. 1974, 84. 135. Wu, P. Y. K. in Phototherapy in the Newborn (edited by Odell and others); p.150. National Academy of Science, Washington, D.C., 1974. 4. Foote, C. S. ibid, p. 21. 5. Sandor, G. Lancet, 1973, 1, 1384. 6. Goyanes-Villaescusa, V. J., Ugarte, M., Vazues, A. ibid. 1977, ii, 1084. 7. Latt, S. A. Proc. Nat, Acad. Sci. U.S.A. 1973, 70, 3395. 8. Perry, P., Wolff, S. Nature, 1974, 251, 156. 9. Latt, S. A. Proc. nat, Acad. Sci. U.S.A. 1974, 71, 4162. 10. Perry, P., Evans, H. J. Nature, 1975, 258, 121. 11. Carrano, A. B., and others, ibid. 1978, 271, 551. 12. Hatchard, C. G., Parker, C. A. Proc. R. Soc. A. 1956, 235, 518. 1. 2. 3.
158 TABLE II-EFFECT OF BILIRUBIN PLUS LIGHT ON S.C.E.
FREQUENCIES
IN ADULT HUMAN LYMPHOCYTES: IN-VITRO
STUDIES
TOTAL LYMPHOCYTE-COUNTS IN BREAST CANCER
SIR,-Mr Bainbridge and his colleagues’ claim
to
have
reduced absolute active-T-lymphocyte count in the peripheral blood in patients with stage-2 breast cancer. However, this difference may be more apparent than real, since they arrived at this conclusion by carrying out t-tests on all the possible pairs of eight columns. This type of analysis is inappropriate2 since it increases the odds of accepting a result as being significant when in fact it is due to chance. The odds in this case are increased 28 (gC2) times. One-way analysis of variance of the entire data shows that there is no significant difference between any of the categories (Fs , 59=1.27).
found
a
Department of Oto-Rhino-Laryngology, University of Liverpool, Ear Nose and Throat Infirmary, Liverpool L7 7DF *
P. M. STELL
Range of the mean s.c.E. frequency in the three subjects.
apy). Peripheral lymphocytes were cultured for 3 days in the presence of 0.1 mmol/1 5-bromodeoxyuridine, 0.4 umol/1 5-fluorodeoxyuridine, 6 µmol/1 uridine, and 0.1mmol/1 deoxycytidine, harvested by standard procedures, ’stained with 33258 Hoechst and Giemsa, and photographed.7,s Typically, 15-25 cells from each sample were scored for s.c.E. formation. All samples were processed in a double-blind fashion through s.c.E. analysis and scoring. In five samples obtained from untreated infants, the average s.c.E. frequencies per cell were 10.60 ± 0.56 and 9-00 ± 0.86 for the first and second samples respectively (table i). In the ten on phototherapy the values were 9.0 5 + 0.53 before and 9.01 ± 0.39 after treatment (table i). Chromosome breakage was negligible in both treated and untreated groups. Phototherapy caused no significant increase in s.c.E.s either in paired samples from treated individuals or when the two groups of infants are compared. Peripheral lymphocytes from three healthy adult volunteers were exposed to dimethylsulphoxide (D.M.S.o.) (final concentration 1%), bilirubin (20 mg/dl), and light (1.4 or 17 J/cm2) from the same source as used for phototherapy. s.c.E. frequencies of adult cells were somewhat greater than those in the infants studied (table n). However, no significant increase in s.c.E.s could be attributed to the bilirubin or white fluorescent light, separately or in combination. Inter-individual differences in s.c.E. frequencies were within typical limits. This discrepancy between our findings and the earlier report6 may in part reflect methodological differences (e.g., gestational age, duration of phototherapy). Goyanes-Villaescusa et al. did not use internal controls to monitor intra-individual variations in s.c.E. frequencies. Our data on in-vivo exposure (table i) are also supported by s.c.E. measurements on adult lymphocytes treated in vitro (table u), in which the illumination dose reaching cells probably exceeded that received in vivo. Thus, while our observations cannot exclude completely the possibility that phototherapy causes some adverse genetic effects, they do rule against the suggestion that phototherapy induces sister chromatid exchanges in circulat-
ing lymphocytes. Supported in part by research grants from the American Cancer Society (VC-144B) and the National Foundation March of Dimes (1-353); S.L. is the recipient of a Research Career Development Award (GM 00122) from the National Institutes of Health. We thank the staff of the Special Care Nursery, Boston Hospital for Women, for their cooperation. Department for Medicine, Children’s Hospital Medical Center;
Lying-in-Division; Boston Hospital for Women, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, U.S.A.
ALAN L. SCHWARTZ F. SESSIONS COLE FREDERICK FIEDOREK DEBORAH MATTHEWS INDER PAIKA IVAN D. FRANTZ SAMUEL A. LATT
*.* This letter has been shown to Mr leagues, whose reply follows.-ED.L.
Bainbridge and his col-
have found a reduced absolute but to have found a reduced total T-lymphocyte lymphocyte-count in patients with stage-II breast cancer. We are aware of the relevance of Mr Stell’s comments, but for 6 groups, not 8 as he states. The hypothesis that stage-II breastcancer patients have lower lymphocyte-counts than controls was suggested by the results of Teasdale et al. These workers apparently used the same statistical methods as we did, but a one-way analysis of variance applied to their data gives a highly significant result (Fs ta=595, P<0.001). In view of this we feel there is in looking at the stage II v. controls comparison individually, and when this was done in our study the difference was significant in Student’s t test, as stated. Our results for stage-II patients compared with controls are consistent with those of Teasdale et al. and together these results constitute sufficiently strong evidence to merit further
SIR,-We do
active
not
claim
to
count
justification
investigation. Surgical Immunology Unit, Clinical Research Block, Queen Elizabeth Hospital, Queen Elizabeth Medical Centre, Birmingham B15 2TH
E. T. BAINBRIDGE
C. H. J. FORD C. E. NEWMAN J. R. SHELTON
PLASMA-CALCITONIN IN WOMEN
SiR,-We were interested to have the comments of Professor Holló4 and Dr HeathS on our paper on plasma-calcitonin. Hollo’s suggestions certainly deserve further investigation. Heath agrees with our conclusions, but he takes our strictures on earlier analytical methods too personally, although we still retain some reservations about his findings. His assay is less sensitive than ours (detection limits 256 v. 8 pg/ml). Further, the effect of a 4 h infusion of calcium adduced in support of the validity of his findings is not convincing: diurnal variation produces the same changes. One further small point: there is no discrepancy between our two papers 7.8 because the women in our earlier paper were 1. Bainbridge, E. T., Ford, C. H. J., Newman, C. E. Lancet, 1978, i, 1203. 2. Pollard, J. H. Numerical and Statistical Techniques; p. 175. London, 1977. 3. Teasdale, C., Thatcher, J., Whitehead, R. H. Chare, M. J. B., Hughes, L.E. Lancet, 1977, i, 543. 4. Holló, I. Lancet, 1978, i, 1362. 5. Heath, H. III ibid. 6. Heath, H. III, Sizemore, G. W. J. clin. Invest. 1977, 60, 1135. 7 Hillyard, C J., Cooke, T. J. C., Coombes, R. C., Evans, I. M. A., Maclntyre, I. Clin. Endocr. 1977, 6, 291. 8. Hillyard, C. J., Stevenson, J. C. MacIntyre, I. Lancet, 1978, i, 961.
responsiveness scalean improved, less cumbersome, and more practical instrument for coma measurement than others. All patients were grade 3, 4, or 5 on the scale. They ranged in age from 4 to 80 years (mean 22). Coma was secondary to head injury in ten patients, hypoxia in four, and brain tumour, with prolonged postoperative unconsciousness, in two. All coma or
diagnoses were supported by angiography and/or computerised tomographic scanning. Patients with traumatic, acute epidural, subdural, or intracerebral hxmorrhage were excluded from the series. The first neurological examinations were done within 6 h of onset of coma and repeated daily. I.A.H.P. environmental enrichment programmes were started 12-24 h after admission to hospital, except in the two postoperative brain-tumour patients whose programmes started 10 and 14 days after surgery. Follow-up has ranged from several days to 10 months. There have been no deaths. All sixteen patients have fully recovered -from coma. Of twelve patients who have regained functional independence and are home, eight have reaquired their premorbid condition and have no detectable deficit. The other four, although still displaying some focal physical deficit or adaptive behaviour disorder, are recovering progressively. One patient, more recently admitted, is still in hospital. Two others, though alert, are in other institutions because of severe physical handicaps and lack of family to care for them. Of a comparable group of fourteen consecutive patients, also in severe coma (all grade 3-5 on the Glasgow scale), admitted to hospital during the previous 12-month period and followed up by one of us (M.D.D.), but not given programmes of environmental enrichment, eleven died (79%). The improved outcome in the I.A.H.P.-managed warrants continuation of this study.
EFFECT OF PHOTOTHERAPY ON SISTER CHROMATID EXCHANGE IN PREMATURE INFANTS first described in 1958,1 is now the method for reducing serum-bilirubin levels in jaundiced infants. Few clinically adverse side-effects directly due to phototherapy have been reported.2,3However, photosensitised damage of nucleic acids and proteins has been described in a number of biological systems.4 While no mutagenic effects of phototherapy have been detected on conventional chromosome analysis,5 Goyanes-Villaescusa et a1.6 concluded that phototherapy does increase the frequency of sister chromatid exchange (S.C.E.) in human lymphocyte chromosomes. s.c.E. induction, simply detected by bromodeoxyuridine-dye techniques,’8 is, in turn, considered to be a sensitive index of mutagen-carcinogeti exposure.8-1O However, s.c.E. analyses in our laboratory do not support the contention that phototherapy or in-vitro exposure of cells to bilirubin plus
SIR,-Phototherapy,
most common
light significantly
increase
lymphocyte
frequencies."
s.c.E.
TABLE I-EFFECT OF PHOTOTHERAPY ON S.C.E. LYMPHOCYTES FROM PREMATURE INFANTS
FREQUENCIES
IN
(S.C.E./CELL)
This letter condenses two papers-The Child in Coma (E.B.L.) and Coma recovery (M.D.D.)-presented to the llth annual meeting of the World Organisation for Human Potential, cosponsored by the National Aeronautics and Space Administration/Ames Research Center and the Institutes for the Achievement of Human Potential, at Moffett Field, California, on May 18,1978. Institutes for the Achievement
of Human Potential,
Philadelphia, Pennsylvania 19118,
U.S.A.
Neurological Surgery and Neurology, Freeport, N.Y.
EDWARD B. LEWINN
MIHAI D.
DIMANCESCU
* 29-35weeks of gestation. t Mean+ s.E.M. (and no. of cells). t Mean+ s.E. of the individual sample means. § Post-treatment values.
PROSTAGLANDIN-SYNTHESIS INHIBITORS IN PROPHYLAXIS OF FOOD INTOLERANCE
SiR,—I have had total lactose intolerance for the past twenty years. After reading the article by Dr Buisseret and his colleagues,’ I took 975 mg aspirin followed, twenty minutes later, by a heavy dairy meal consisting of a pint of ice cream, two glasses of milk, half a pound of Swiss cheese, and two ounces of butter. There were none of the customary immediate or delayed symptoms of malabsorption (borborygmi, cramps,
diarrhoea, tenesmus). The next test again followed 975 mg aspirin, and consisted of two large slices of chocolate cheese cake. Again I was free of retaliatory symptoms. I have subsequently conducted over twenty challenges, all with favourable results. My experience supports the success of Buisseret et al. with, among others, a lactose malabsorber in whom aspirin prevented symptoms after ingestion of 100 ml of cream. Department of Psychiatry, School of Medicine, Yale University, New
Haven, Connecticut 06510, U.S.A.
6. Jennett, B., Teasdale, G. Lancet, 1977, i, 878. 1. Buisseret, P. D., Youlten, L. J. F., Heinzelmann, D. I.,
1978, i, 906.
JULIAN LIEB Lessof,
F. H. Lancet,
Fifteen infants 880-1950 g, less than 58 h old, with bilirubin levels of 3-10 mg/dl, and not critically ill-were selected at random on admission to the neonatal intensive-care unit at the Boston Hospital for Women. 1 ml peripheral blood was obtained before and after 24-48 h of continuous phototherapy in a ’Narco Isolette’ phototherapy unit (Narco Medical Co.,
Warminister, Pennsylvania) containing
8
new
’Sylvania Day-
light’ bulbs (F20T12-D) set 24 cm above the infant. The incidental light energy from this apparatus, measured by chemical actinometry12 was approximately 600 W;cm2, calculated for a wavelength of 490 nm. Two blood-samples 24-48 h apart were obtained from control infants (not undergoing phototherCremer, R. J., Perryman, P. W., Richards, D. H., Lancet, 1958, i, 1094. Behrman, R. E., and others, J. Pediat. 1974, 84. 135. Wu, P. Y. K. in Phototherapy in the Newborn (edited by Odell and others); p.150. National Academy of Science, Washington, D.C., 1974. 4. Foote, C. S. ibid, p. 21. 5. Sandor, G. Lancet, 1973, 1, 1384. 6. Goyanes-Villaescusa, V. J., Ugarte, M., Vazues, A. ibid. 1977, ii, 1084. 7. Latt, S. A. Proc. Nat, Acad. Sci. U.S.A. 1973, 70, 3395. 8. Perry, P., Wolff, S. Nature, 1974, 251, 156. 9. Latt, S. A. Proc. nat, Acad. Sci. U.S.A. 1974, 71, 4162. 10. Perry, P., Evans, H. J. Nature, 1975, 258, 121. 11. Carrano, A. B., and others, ibid. 1978, 271, 551. 12. Hatchard, C. G., Parker, C. A. Proc. R. Soc. A. 1956, 235, 518. 1. 2. 3.
158 TABLE II-EFFECT OF BILIRUBIN PLUS LIGHT ON S.C.E.
FREQUENCIES
IN ADULT HUMAN LYMPHOCYTES: IN-VITRO
STUDIES
TOTAL LYMPHOCYTE-COUNTS IN BREAST CANCER
SIR,-Mr Bainbridge and his colleagues’ claim
to
have
reduced absolute active-T-lymphocyte count in the peripheral blood in patients with stage-2 breast cancer. However, this difference may be more apparent than real, since they arrived at this conclusion by carrying out t-tests on all the possible pairs of eight columns. This type of analysis is inappropriate2 since it increases the odds of accepting a result as being significant when in fact it is due to chance. The odds in this case are increased 28 (gC2) times. One-way analysis of variance of the entire data shows that there is no significant difference between any of the categories (Fs , 59=1.27).
found
a
Department of Oto-Rhino-Laryngology, University of Liverpool, Ear Nose and Throat Infirmary, Liverpool L7 7DF *
P. M. STELL
Range of the mean s.c.E. frequency in the three subjects.
apy). Peripheral lymphocytes were cultured for 3 days in the presence of 0.1 mmol/1 5-bromodeoxyuridine, 0.4 umol/1 5-fluorodeoxyuridine, 6 µmol/1 uridine, and 0.1mmol/1 deoxycytidine, harvested by standard procedures, ’stained with 33258 Hoechst and Giemsa, and photographed.7,s Typically, 15-25 cells from each sample were scored for s.c.E. formation. All samples were processed in a double-blind fashion through s.c.E. analysis and scoring. In five samples obtained from untreated infants, the average s.c.E. frequencies per cell were 10.60 ± 0.56 and 9-00 ± 0.86 for the first and second samples respectively (table i). In the ten on phototherapy the values were 9.0 5 + 0.53 before and 9.01 ± 0.39 after treatment (table i). Chromosome breakage was negligible in both treated and untreated groups. Phototherapy caused no significant increase in s.c.E.s either in paired samples from treated individuals or when the two groups of infants are compared. Peripheral lymphocytes from three healthy adult volunteers were exposed to dimethylsulphoxide (D.M.S.o.) (final concentration 1%), bilirubin (20 mg/dl), and light (1.4 or 17 J/cm2) from the same source as used for phototherapy. s.c.E. frequencies of adult cells were somewhat greater than those in the infants studied (table n). However, no significant increase in s.c.E.s could be attributed to the bilirubin or white fluorescent light, separately or in combination. Inter-individual differences in s.c.E. frequencies were within typical limits. This discrepancy between our findings and the earlier report6 may in part reflect methodological differences (e.g., gestational age, duration of phototherapy). Goyanes-Villaescusa et al. did not use internal controls to monitor intra-individual variations in s.c.E. frequencies. Our data on in-vivo exposure (table i) are also supported by s.c.E. measurements on adult lymphocytes treated in vitro (table u), in which the illumination dose reaching cells probably exceeded that received in vivo. Thus, while our observations cannot exclude completely the possibility that phototherapy causes some adverse genetic effects, they do rule against the suggestion that phototherapy induces sister chromatid exchanges in circulat-
ing lymphocytes. Supported in part by research grants from the American Cancer Society (VC-144B) and the National Foundation March of Dimes (1-353); S.L. is the recipient of a Research Career Development Award (GM 00122) from the National Institutes of Health. We thank the staff of the Special Care Nursery, Boston Hospital for Women, for their cooperation. Department for Medicine, Children’s Hospital Medical Center;
Lying-in-Division; Boston Hospital for Women, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, U.S.A.
ALAN L. SCHWARTZ F. SESSIONS COLE FREDERICK FIEDOREK DEBORAH MATTHEWS INDER PAIKA IVAN D. FRANTZ SAMUEL A. LATT
*.* This letter has been shown to Mr leagues, whose reply follows.-ED.L.
Bainbridge and his col-
have found a reduced absolute but to have found a reduced total T-lymphocyte lymphocyte-count in patients with stage-II breast cancer. We are aware of the relevance of Mr Stell’s comments, but for 6 groups, not 8 as he states. The hypothesis that stage-II breastcancer patients have lower lymphocyte-counts than controls was suggested by the results of Teasdale et al. These workers apparently used the same statistical methods as we did, but a one-way analysis of variance applied to their data gives a highly significant result (Fs ta=595, P<0.001). In view of this we feel there is in looking at the stage II v. controls comparison individually, and when this was done in our study the difference was significant in Student’s t test, as stated. Our results for stage-II patients compared with controls are consistent with those of Teasdale et al. and together these results constitute sufficiently strong evidence to merit further
SIR,-We do
active
not
claim
to
count
justification
investigation. Surgical Immunology Unit, Clinical Research Block, Queen Elizabeth Hospital, Queen Elizabeth Medical Centre, Birmingham B15 2TH
E. T. BAINBRIDGE
C. H. J. FORD C. E. NEWMAN J. R. SHELTON
PLASMA-CALCITONIN IN WOMEN
SiR,-We were interested to have the comments of Professor Holló4 and Dr HeathS on our paper on plasma-calcitonin. Hollo’s suggestions certainly deserve further investigation. Heath agrees with our conclusions, but he takes our strictures on earlier analytical methods too personally, although we still retain some reservations about his findings. His assay is less sensitive than ours (detection limits 256 v. 8 pg/ml). Further, the effect of a 4 h infusion of calcium adduced in support of the validity of his findings is not convincing: diurnal variation produces the same changes. One further small point: there is no discrepancy between our two papers 7.8 because the women in our earlier paper were 1. Bainbridge, E. T., Ford, C. H. J., Newman, C. E. Lancet, 1978, i, 1203. 2. Pollard, J. H. Numerical and Statistical Techniques; p. 175. London, 1977. 3. Teasdale, C., Thatcher, J., Whitehead, R. H. Chare, M. J. B., Hughes, L.E. Lancet, 1977, i, 543. 4. Holló, I. Lancet, 1978, i, 1362. 5. Heath, H. III ibid. 6. Heath, H. III, Sizemore, G. W. J. clin. Invest. 1977, 60, 1135. 7 Hillyard, C J., Cooke, T. J. C., Coombes, R. C., Evans, I. M. A., Maclntyre, I. Clin. Endocr. 1977, 6, 291. 8. Hillyard, C. J., Stevenson, J. C. MacIntyre, I. Lancet, 1978, i, 961.