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ZINC DEFICIENCY
1317 as controls, these occupations lose their apparent advantage and, if those with the lowest mortality are reviewed, one finds that all of them are heavy jobs:
used
ZINC DEFICIENCY zinc deficiency (Feb. 10, p. 299) SIR,—Your raised important questions about the biological role of zinc. Subsequently, Andresen and his colleagues (April 14, p. 839) drew attention to a syndrome in calves which is characterised by symptoms similar to those of zinc deficiency and a severe hypoplasia of the lymphoid system. Most interestingly, the immune system of these animals can be restored by treatment with zinc oxide.l This suggests a possible role of Zn++ in the development of the immune system. The regulation of lymphocyte proliferation can be studied in vitro by culturing them with a variety of substances such as phytomitogens, antigens, antisera, and allogeneic cells. Under these conditions, otherwise resting lymphocytes will be induced to synthesise D.N.A. and divide. We have reported that human peripheral lymphocytes can be stimulated in a similar fashion by Zn++.3,44 Among the various substances that induce lymphocyte stimulation in vitro, zinc is the only one that occurs naturally in the human body. This observation strengthens the hypothesis that zinc plays a major role in regulating lymphocyte proliferation at various times during prenatal and postnatal life. We also want to suggest the use of zinc in clinical trials with immunodeficiency patients, since adverse side-effects have not been observed after oral zinc
editorial
on
Groups with lowest men/wives S.M.R. quotient -
-
-
-
same principle at the opposite end of the emotional stress emerges even more strongly as spectrum, a factor in the causation of ischaemic heart-disease, with airline pilots taking the lead:
Applying the
Groups with highest
men/wiv!!.s _s..._R-
quotient -.
-
-
medtrannr) National Cancer Institute, Bethesda, Maryland 20014, U.S.A. Klinikum Steglitz der Freien Universität Berlin.
H. KIRCHNER. H. RÜHL.
CARDIOVASCULAR FITNESS OF PILOTS
SIR,-Dr A. M. Adelstein, of the Office of Population Censuses and Surveys, has rightly pointed out an error in the article (May 12, p. 1048) on the cardiovascular fitness of pilots. This concerned the standardised mortality ratio (S.M.R.) of occupational group 192, which includes pilots, recorded in the 1961 Decennial Occupational Mortality tables. The
statement
should have read that this group has the
highest incidence of ischxmic heart-disease when the wives of the men in that group are used as controls to eliminate non-occupational factors. The simple s.M.R. of an occupation is not only influenced by the specific factors of that occupation but also by all the social and environmental factors that go with it. The wives share these nonoccupational influences, the only difference from their husbands being the occupation and their sex. The fact that there is a recognised sex-difference in mortality from ischsemic heart-disease does not invalidate using the wives as controls, for the s.M.R. is not concerned with net differences but the ratio of observed to expected deaths. Thus, it is suggested that a more useful means of comparison between occupational groups is not the S.M.R. but the quotient of the S.M.R. of the men to that of their
wives. The value of this technique may be demonstrated by its to the jobs which seem to confer some protection from ischsemic heart-disease. Physical inactivity is recognised as an aaiological factor, and thus one might expect not to find sedentary occupations with very low S.M.R. ; however, typists (group 220), paper-products makers (131), university teachers (286), and managers in building (273) all have low S.M.R.S. When the wives are
application
1. 2. 3. 4.
Brummerstedt, E., Flagstad, T., Basse, A., Andresen, E. Acta path. microbiol. scand. 1971, sect. A, 79, 686. Oppenheim, J. J. Fedn Proc. 1968, 27, 21. Kirchner, H., Rühl, H. Expl Cell Res. 1970, 61, 229. Rühl, H., Kirchner, H., Bochert, G. Proc. Soc. exp. Biol. Med. 1971, 137, 1089.
The numbers involved are small, the figures considerably of date, and the comparison of ratios liable to create stress among statisticians. We hope, however, that those more numerically adept than ourselves will improve on this attempt to sharpen the focus on mortality in relation to occupation. Department of Chemical Pathology, St. Mary’s Hospital Medical School, M. E. CARRUTHERS St. Mary’s Hospital, R. C. HOLMES. London W2. out
BASEMENT-MEMBRANE THICKNESS OF RECTAL CAPILLARIES IN DIABETES
SIR,-Dr Farid and others (April 14,
p. 837) have basement-membrane thickness of the rectal capillaries in diabetic and non-diabetic subjects. In 1968 we reported 1 a simple microscopic method with polarised light to demonstrate thickening of the basement membrane of rectal capillaries in diabetes: the birefringence of basement membrane is in a direct proportion to rectalcapillary basement-membrane thickening. Capillaries in the rectal wall are particularly suitable for measurements with polarised light. We observed in all of 25 patients with diabetes mellitus (known for at least a year) a significantly greater thickening of basement membrane (0-02> P > 0-01) than in 22 normal controls. Also in 5 out of 8 patients with newly recognised diabetes mellitus, thickening of the basement membrane in rectal capillaries was detectable.2 Our data confirm the studies of Siperstein et al.but are at variance with the observations of Farid et al. Because no thickening of basement membrane is to be found in a woman with hyperglycaemia after pancreatectomy
studied
Missmahl, H.-P., Riemann, J. Klin. Wschr. 1968, 46, 374. Meyer, H.-W., Missmahl, H.-P. Med. Welt, 1972, 23, 683. 3. Siperstein, M., Unger, R. H., Madison, L. L. J. clin. Invest. 1968, 47, 1973. 1. 2.
used
ZINC DEFICIENCY zinc deficiency (Feb. 10, p. 299) SIR,—Your raised important questions about the biological role of zinc. Subsequently, Andresen and his colleagues (April 14, p. 839) drew attention to a syndrome in calves which is characterised by symptoms similar to those of zinc deficiency and a severe hypoplasia of the lymphoid system. Most interestingly, the immune system of these animals can be restored by treatment with zinc oxide.l This suggests a possible role of Zn++ in the development of the immune system. The regulation of lymphocyte proliferation can be studied in vitro by culturing them with a variety of substances such as phytomitogens, antigens, antisera, and allogeneic cells. Under these conditions, otherwise resting lymphocytes will be induced to synthesise D.N.A. and divide. We have reported that human peripheral lymphocytes can be stimulated in a similar fashion by Zn++.3,44 Among the various substances that induce lymphocyte stimulation in vitro, zinc is the only one that occurs naturally in the human body. This observation strengthens the hypothesis that zinc plays a major role in regulating lymphocyte proliferation at various times during prenatal and postnatal life. We also want to suggest the use of zinc in clinical trials with immunodeficiency patients, since adverse side-effects have not been observed after oral zinc
editorial
on
Groups with lowest men/wives S.M.R. quotient -
-
-
-
same principle at the opposite end of the emotional stress emerges even more strongly as spectrum, a factor in the causation of ischaemic heart-disease, with airline pilots taking the lead:
Applying the
Groups with highest
men/wiv!!.s _s..._R-
quotient -.
-
-
medtrannr) National Cancer Institute, Bethesda, Maryland 20014, U.S.A. Klinikum Steglitz der Freien Universität Berlin.
H. KIRCHNER. H. RÜHL.
CARDIOVASCULAR FITNESS OF PILOTS
SIR,-Dr A. M. Adelstein, of the Office of Population Censuses and Surveys, has rightly pointed out an error in the article (May 12, p. 1048) on the cardiovascular fitness of pilots. This concerned the standardised mortality ratio (S.M.R.) of occupational group 192, which includes pilots, recorded in the 1961 Decennial Occupational Mortality tables. The
statement
should have read that this group has the
highest incidence of ischxmic heart-disease when the wives of the men in that group are used as controls to eliminate non-occupational factors. The simple s.M.R. of an occupation is not only influenced by the specific factors of that occupation but also by all the social and environmental factors that go with it. The wives share these nonoccupational influences, the only difference from their husbands being the occupation and their sex. The fact that there is a recognised sex-difference in mortality from ischsemic heart-disease does not invalidate using the wives as controls, for the s.M.R. is not concerned with net differences but the ratio of observed to expected deaths. Thus, it is suggested that a more useful means of comparison between occupational groups is not the S.M.R. but the quotient of the S.M.R. of the men to that of their
wives. The value of this technique may be demonstrated by its to the jobs which seem to confer some protection from ischsemic heart-disease. Physical inactivity is recognised as an aaiological factor, and thus one might expect not to find sedentary occupations with very low S.M.R. ; however, typists (group 220), paper-products makers (131), university teachers (286), and managers in building (273) all have low S.M.R.S. When the wives are
application
1. 2. 3. 4.
Brummerstedt, E., Flagstad, T., Basse, A., Andresen, E. Acta path. microbiol. scand. 1971, sect. A, 79, 686. Oppenheim, J. J. Fedn Proc. 1968, 27, 21. Kirchner, H., Rühl, H. Expl Cell Res. 1970, 61, 229. Rühl, H., Kirchner, H., Bochert, G. Proc. Soc. exp. Biol. Med. 1971, 137, 1089.
The numbers involved are small, the figures considerably of date, and the comparison of ratios liable to create stress among statisticians. We hope, however, that those more numerically adept than ourselves will improve on this attempt to sharpen the focus on mortality in relation to occupation. Department of Chemical Pathology, St. Mary’s Hospital Medical School, M. E. CARRUTHERS St. Mary’s Hospital, R. C. HOLMES. London W2. out
BASEMENT-MEMBRANE THICKNESS OF RECTAL CAPILLARIES IN DIABETES
SIR,-Dr Farid and others (April 14,
p. 837) have basement-membrane thickness of the rectal capillaries in diabetic and non-diabetic subjects. In 1968 we reported 1 a simple microscopic method with polarised light to demonstrate thickening of the basement membrane of rectal capillaries in diabetes: the birefringence of basement membrane is in a direct proportion to rectalcapillary basement-membrane thickening. Capillaries in the rectal wall are particularly suitable for measurements with polarised light. We observed in all of 25 patients with diabetes mellitus (known for at least a year) a significantly greater thickening of basement membrane (0-02> P > 0-01) than in 22 normal controls. Also in 5 out of 8 patients with newly recognised diabetes mellitus, thickening of the basement membrane in rectal capillaries was detectable.2 Our data confirm the studies of Siperstein et al.but are at variance with the observations of Farid et al. Because no thickening of basement membrane is to be found in a woman with hyperglycaemia after pancreatectomy
studied
Missmahl, H.-P., Riemann, J. Klin. Wschr. 1968, 46, 374. Meyer, H.-W., Missmahl, H.-P. Med. Welt, 1972, 23, 683. 3. Siperstein, M., Unger, R. H., Madison, L. L. J. clin. Invest. 1968, 47, 1973. 1. 2.