- Email: [email protected]
PLACENTAL TRANSMISSION AND FETAL DISTRIBUTION OF CLIOQUINOL
938 There
deaths and no cases of severe haemorrhage, although 5% required a blood-transfusion. 24% had minor postoperative infections, of which half were wound infections. 1 patient had a paralytic ileus and required a further laparotomy and division of adhesions. In 1-2% a deep-vein thrombosis developed; and there was 1 pulwere no
monary embolus. All these cases coagulants. 2 patients (0-8%)
were
treated with anti-
required dilatation and
curettage for retained products six weeks after operation. 4 (1-6%) developed endometriosis nodules in the abdominal These were excised scar several months after operation. and have not recurred. Stay in hospital was kept to a minimum. 56%were dis-
charged on the sixth day, and by the eighth day over 90% had been discharged. There have been 13 further pregnancies in unsterilised patients and there were no problems relating to the uterine scar. Oxytocic drugs were given in labour without complications. The second stage of labour was kept short. There have been no cases of involuntary infertility so far. In pregnancies beyond 12 weeks this method has the advantages of direct vision, easy control of haemorrhage, little risk of intrauterine infection, and (almost always) complete removal of all placental tissue. This, combined with the acceptably short stay in hospital, compares very favourably with vaginal termination, whether by curettage, vacuum aspiration, or prostaglandin induction, even if sterilisation is not performed. Wythenshawe Maternity Hospital, Manchester 23.
J. HIGGINBOTTOM.
HL-A AND MALIGNANT MELANOMA
by a modification of Terasaki’s two-step lymphocytotoxicity microtechnique.1 Our findings do not support those of R. Vanwijk and C. Bouillenne, of Liege, reported on March 5-6, 1973, in Lyons at the Third International Symposium of Malignant Melanoma. They typed for 19 HL-A specificities by the Kissmeyer-Nielsen lymphocytotoxic microtechnique. In 31 patients, compared with 840 healthy unrelated individuals, HL-A 9 appeared to have an increased frequency. The frequency of HL-A 11 in 31 patients was insignificantly different from the controls, although their first 25 patients showed almost a complete absence of this antigen. We appreciate that difficulties may arise when the laboratories, the populations tested, the methods employed, and the typing sera all differ, as in this case. Moreover, when analysing data from a survey with a small sample size, great caution must be exercised. This last factor, in particular, may explain why the two sets of conclusions cities
in agreement. Tissue Typing Laboratory, Blood Transfusion Unit,
are not
ANNE L. CORDON.
Westminster Hospital.
PLACENTAL TRANSMISSION AND FETAL DISTRIBUTION OF CLIOQUINOL
small
amount of intravenously injected transferred from the blood to the central nervous system.2 We have administered radioactive clioquinol to pregnant mice and have examined its distribution in maternal and fetal tissues to determine whether there is placental transfer of clioquinol from the mother to
SIR,-In mice,
a
[C]-clioquinol
was
DISTRIBUTION
[14C]-CLIOQUINOL
OF
TISSUES
(ng.
per
IN
MATERNAL
AND
FETAL
g.)
SIR,-A preliminary survey of 54 patients with malignant shows frequencies when individuals of the melanoma
no significant difference in HL-A compared with 107 healthy, unrelated same ethnic background living in the
*
Ratio of chloroform
or
water-soluble fraction to liver.
to
total fraction.
t Ratio of concentration of cerebrum
HL-A
frequencies
in
patients with malignant melanoma
and in
controls.
Even though W18 is an infrequent, weakly expressed antigen, this antigen appeared with an almost significantly greater frequency (x2= 8); W18 may prove interesting when more patients are studied. Both the controls and the patients were typed for 23 HL-A specifisame area.
the fetus. On the 16th day of gestation four pregnant inbred A-strain mice were injected intramuscularly with 50 mg./kg. of [2,3,4,-C]-clioquinol emulsified with carboxymethyl cellulose (specific activity 1 -52 mCi per mmole [Daiich Isotope. Co.]). Two hours after injection, mice were killed by exsanguination. Fetuses were removed through a midline abdominal incision. The fetal livers and brains were removed, suspended in Ringer’s solution, and homogenised in aTeflon’ homogeniser. The remainder of the fetus was similarly treated. Radioactivity was measured as previously described.2 Radioactivity was widely distributed in all fetal tissues, and it was less than the activity of maternal liver and was similar to the activity of the maternal brain. The ratio of radioactivity in the chloroform-soluble fractions (which 1. 2.
Terasaki, P., McClelland, J. D. Nature, 1964, 206, 998. Ogata, M., Watanabe, S., Tateishi, J., Kuroda, S., Tomokuni, K., Otsuki, S. Acta Med. Okoyama, 1971, 25, 199.
939 contained non-conjugated clioquinol) to that in the total fraction of the fetus ranged from 20% to 72%, indicating that non-conjugated clioquinol was present in fetal tissue. In the fetus, the ratio of total clioquinol in the brain to that in the liver was 1-07/1-00, and in the mother this ratio was 0-20/1-00, suggesting that the transfer of clioquinol from the blood to the brain is facilitated in the fetus. Although there must be differences in placental transfer of clioquinol in man and mice, our experiment suggests that placental transfer in man is a possibility. Departments of Public Health and Neuropsychiatry, Okayama University Medical School, Shikata-cho, Okayama City, Japan.
MASANA OGATA SHOSUKE WATANABE
JUN TATEISHI SHIGETOSHI KURODA SHOHEI KIRA SABURO OTSUKI.
SMOKING AND CANCER
SIR,-Dr Mehrishi (March 24, p. 666) pleads for intensified research on the mechanisms whereby smoking causes cancer. In particular, he urges investigation of the idea that free radicals in the products of tobacco combustion induce mutations and cancer. I have used epidemiological evidence to test this and other causal hypotheses of the association between cigarette smoking and lung cancer. Secular increases in incidence arising from increased rates of somatic mutation should be associated with earlier onset: statistics from countries with a high incidence of lung cancer should reveal a relatively early onset.
Fig. 1 shows a vertical analysis of recorded age-specific death(cLP/dt) from lung cancer in men, England and Wales, by 5-year periods, 1951-70. Fig. 2 shows a similar analysis for Finland, 1960-61, another country which records very high rates, and Portugal, 1960-61, which records very low rates. Despite large differences in absolute rates, we see, unexpectedly, All a remarkable similarity in the form of the age patterns. rates
death-rates from cancer of lung, and trachea in men, in relation to estimated age at for Finland and Portugal. t
Fig. 2-Age-specific
bronchus, initiation,
the data, above an initiation age t of about 35 years, are fitted by eye to the stochastic function 1: dP/dt=10k S{t4 exp( -kt5)}{1-exp( -kt5)} This equation is based on the biological model 1,2that " lateonset " lung cancer in males is initiated by 5 random somatic gene mutations in each of 2 independent growth-control stem cells. The mutant stem cells propagate " forbidden clones " of descendant cells: interactions between the products of these cells and target epithelial cells promote the neoplastic transformation. Parameter S, as calculated from mortality statistics, represents the proportion of the male population that appears to be at genetic risk with respect to recorded death from lung cancer;k is a kinetic constant proportional to the fifth power of the average rate of somatic gene mutation. I.2assume that an average latent period of about 2-5 years elapses between the end of initiation and death. (Strictly, the equation requires that mortality from lung cancer is insufficient to distort appreciably the structure of the general population. The error involved in this assumption can be eliminated by dividing by (1-Pt), but other errors, including those of diagnosis, are likely to be much
larger.)
Fig. 1-Registrar General’s statistics for age-specific deathrates (dP/dt) from lung cancer (7th I.C.D. 162 and 163), males, England and Wales, in relation to estimated age (t) at initiation. Data for 5-year periods, 1951-70. Paradoxically, increases in death-rates are highest in the age-groups (60+ yr.) in which the percentage of ex-smokers is highest.* The curves are based on a theoretical model (see text). Calculated values of S are as follows: 1951-55, 0-080; 1956-60, 0-115; 1961-65, 0-144, and
1966-70, 0-187. G. F. Statistics of Smoking in the United Research Council, London, 1972.
* Todd,
Kingdom. Tobacco
From fig. 1 we see that death-rates in the higher age-groups increased greatly over the period 1951-70, but not because the rate of somatic mutation increased. On the contrary, if the data are interpreted at their face value, the value of k declined over this period from about 8 x 10-10 yr.-5 to 6 x 10-10 yr.-5. Vertical analysis of the Registrar General’s statistics from 1901 to 1955 indicates, however, that the apparent value ofk remained effectively constant over that period, while S, on the other hand, increased enormously,3 by a factor of over 50. It is difficult to k actually diminished after 1960. The most plausible accept that M. Cancer Mortality for Selected Sites in 24 Countries, no. 4, 1962-63. Sendai, Japan, 1966. 1. Burch, P. R. J. J. theor. Biol. 1966, 12, 397. 2. Burch, P. R. J. Nature, 1970, 325, 512. 3. Burch, P. R. J. Lancet, 1972, ii, 132.
t Segi, M., Kurihara,
deaths and no cases of severe haemorrhage, although 5% required a blood-transfusion. 24% had minor postoperative infections, of which half were wound infections. 1 patient had a paralytic ileus and required a further laparotomy and division of adhesions. In 1-2% a deep-vein thrombosis developed; and there was 1 pulwere no
monary embolus. All these cases coagulants. 2 patients (0-8%)
were
treated with anti-
required dilatation and
curettage for retained products six weeks after operation. 4 (1-6%) developed endometriosis nodules in the abdominal These were excised scar several months after operation. and have not recurred. Stay in hospital was kept to a minimum. 56%were dis-
charged on the sixth day, and by the eighth day over 90% had been discharged. There have been 13 further pregnancies in unsterilised patients and there were no problems relating to the uterine scar. Oxytocic drugs were given in labour without complications. The second stage of labour was kept short. There have been no cases of involuntary infertility so far. In pregnancies beyond 12 weeks this method has the advantages of direct vision, easy control of haemorrhage, little risk of intrauterine infection, and (almost always) complete removal of all placental tissue. This, combined with the acceptably short stay in hospital, compares very favourably with vaginal termination, whether by curettage, vacuum aspiration, or prostaglandin induction, even if sterilisation is not performed. Wythenshawe Maternity Hospital, Manchester 23.
J. HIGGINBOTTOM.
HL-A AND MALIGNANT MELANOMA
by a modification of Terasaki’s two-step lymphocytotoxicity microtechnique.1 Our findings do not support those of R. Vanwijk and C. Bouillenne, of Liege, reported on March 5-6, 1973, in Lyons at the Third International Symposium of Malignant Melanoma. They typed for 19 HL-A specificities by the Kissmeyer-Nielsen lymphocytotoxic microtechnique. In 31 patients, compared with 840 healthy unrelated individuals, HL-A 9 appeared to have an increased frequency. The frequency of HL-A 11 in 31 patients was insignificantly different from the controls, although their first 25 patients showed almost a complete absence of this antigen. We appreciate that difficulties may arise when the laboratories, the populations tested, the methods employed, and the typing sera all differ, as in this case. Moreover, when analysing data from a survey with a small sample size, great caution must be exercised. This last factor, in particular, may explain why the two sets of conclusions cities
in agreement. Tissue Typing Laboratory, Blood Transfusion Unit,
are not
ANNE L. CORDON.
Westminster Hospital.
PLACENTAL TRANSMISSION AND FETAL DISTRIBUTION OF CLIOQUINOL
small
amount of intravenously injected transferred from the blood to the central nervous system.2 We have administered radioactive clioquinol to pregnant mice and have examined its distribution in maternal and fetal tissues to determine whether there is placental transfer of clioquinol from the mother to
SIR,-In mice,
a
[C]-clioquinol
was
DISTRIBUTION
[14C]-CLIOQUINOL
OF
TISSUES
(ng.
per
IN
MATERNAL
AND
FETAL
g.)
SIR,-A preliminary survey of 54 patients with malignant shows frequencies when individuals of the melanoma
no significant difference in HL-A compared with 107 healthy, unrelated same ethnic background living in the
*
Ratio of chloroform
or
water-soluble fraction to liver.
to
total fraction.
t Ratio of concentration of cerebrum
HL-A
frequencies
in
patients with malignant melanoma
and in
controls.
Even though W18 is an infrequent, weakly expressed antigen, this antigen appeared with an almost significantly greater frequency (x2= 8); W18 may prove interesting when more patients are studied. Both the controls and the patients were typed for 23 HL-A specifisame area.
the fetus. On the 16th day of gestation four pregnant inbred A-strain mice were injected intramuscularly with 50 mg./kg. of [2,3,4,-C]-clioquinol emulsified with carboxymethyl cellulose (specific activity 1 -52 mCi per mmole [Daiich Isotope. Co.]). Two hours after injection, mice were killed by exsanguination. Fetuses were removed through a midline abdominal incision. The fetal livers and brains were removed, suspended in Ringer’s solution, and homogenised in aTeflon’ homogeniser. The remainder of the fetus was similarly treated. Radioactivity was measured as previously described.2 Radioactivity was widely distributed in all fetal tissues, and it was less than the activity of maternal liver and was similar to the activity of the maternal brain. The ratio of radioactivity in the chloroform-soluble fractions (which 1. 2.
Terasaki, P., McClelland, J. D. Nature, 1964, 206, 998. Ogata, M., Watanabe, S., Tateishi, J., Kuroda, S., Tomokuni, K., Otsuki, S. Acta Med. Okoyama, 1971, 25, 199.
939 contained non-conjugated clioquinol) to that in the total fraction of the fetus ranged from 20% to 72%, indicating that non-conjugated clioquinol was present in fetal tissue. In the fetus, the ratio of total clioquinol in the brain to that in the liver was 1-07/1-00, and in the mother this ratio was 0-20/1-00, suggesting that the transfer of clioquinol from the blood to the brain is facilitated in the fetus. Although there must be differences in placental transfer of clioquinol in man and mice, our experiment suggests that placental transfer in man is a possibility. Departments of Public Health and Neuropsychiatry, Okayama University Medical School, Shikata-cho, Okayama City, Japan.
MASANA OGATA SHOSUKE WATANABE
JUN TATEISHI SHIGETOSHI KURODA SHOHEI KIRA SABURO OTSUKI.
SMOKING AND CANCER
SIR,-Dr Mehrishi (March 24, p. 666) pleads for intensified research on the mechanisms whereby smoking causes cancer. In particular, he urges investigation of the idea that free radicals in the products of tobacco combustion induce mutations and cancer. I have used epidemiological evidence to test this and other causal hypotheses of the association between cigarette smoking and lung cancer. Secular increases in incidence arising from increased rates of somatic mutation should be associated with earlier onset: statistics from countries with a high incidence of lung cancer should reveal a relatively early onset.
Fig. 1 shows a vertical analysis of recorded age-specific death(cLP/dt) from lung cancer in men, England and Wales, by 5-year periods, 1951-70. Fig. 2 shows a similar analysis for Finland, 1960-61, another country which records very high rates, and Portugal, 1960-61, which records very low rates. Despite large differences in absolute rates, we see, unexpectedly, All a remarkable similarity in the form of the age patterns. rates
death-rates from cancer of lung, and trachea in men, in relation to estimated age at for Finland and Portugal. t
Fig. 2-Age-specific
bronchus, initiation,
the data, above an initiation age t of about 35 years, are fitted by eye to the stochastic function 1: dP/dt=10k S{t4 exp( -kt5)}{1-exp( -kt5)} This equation is based on the biological model 1,2that " lateonset " lung cancer in males is initiated by 5 random somatic gene mutations in each of 2 independent growth-control stem cells. The mutant stem cells propagate " forbidden clones " of descendant cells: interactions between the products of these cells and target epithelial cells promote the neoplastic transformation. Parameter S, as calculated from mortality statistics, represents the proportion of the male population that appears to be at genetic risk with respect to recorded death from lung cancer;k is a kinetic constant proportional to the fifth power of the average rate of somatic gene mutation. I.2assume that an average latent period of about 2-5 years elapses between the end of initiation and death. (Strictly, the equation requires that mortality from lung cancer is insufficient to distort appreciably the structure of the general population. The error involved in this assumption can be eliminated by dividing by (1-Pt), but other errors, including those of diagnosis, are likely to be much
larger.)
Fig. 1-Registrar General’s statistics for age-specific deathrates (dP/dt) from lung cancer (7th I.C.D. 162 and 163), males, England and Wales, in relation to estimated age (t) at initiation. Data for 5-year periods, 1951-70. Paradoxically, increases in death-rates are highest in the age-groups (60+ yr.) in which the percentage of ex-smokers is highest.* The curves are based on a theoretical model (see text). Calculated values of S are as follows: 1951-55, 0-080; 1956-60, 0-115; 1961-65, 0-144, and
1966-70, 0-187. G. F. Statistics of Smoking in the United Research Council, London, 1972.
* Todd,
Kingdom. Tobacco
From fig. 1 we see that death-rates in the higher age-groups increased greatly over the period 1951-70, but not because the rate of somatic mutation increased. On the contrary, if the data are interpreted at their face value, the value of k declined over this period from about 8 x 10-10 yr.-5 to 6 x 10-10 yr.-5. Vertical analysis of the Registrar General’s statistics from 1901 to 1955 indicates, however, that the apparent value ofk remained effectively constant over that period, while S, on the other hand, increased enormously,3 by a factor of over 50. It is difficult to k actually diminished after 1960. The most plausible accept that M. Cancer Mortality for Selected Sites in 24 Countries, no. 4, 1962-63. Sendai, Japan, 1966. 1. Burch, P. R. J. J. theor. Biol. 1966, 12, 397. 2. Burch, P. R. J. Nature, 1970, 325, 512. 3. Burch, P. R. J. Lancet, 1972, ii, 132.
t Segi, M., Kurihara,