- Email: [email protected]
Falling sperm counts
irrespective of high rainfall. By contrast A culicifacies in Barmer is largely dependent on the rainwater. In the IGNP command area a malaria epidemic can occur even without heavy rain (as in 1992-93) whereas in the non-IGNP area heavy rains would predictably be followed by an outbreak. An impact from ENSO is thus demonstrable in only a part of the Thar desert. *B K
Tyagi, R C Chaudhary, S P Yadav
Desert Medicine Research Centre, PO Box 122,
Jodhpur 342005, India
therapeutic use of oestrogens in both males and females. It is important to keep in mind that the relation between falling male sperm counts and environmental oestrogens is a hypothesis with little or no scientific bias. Despite the perturbations of the endocrine system by various chemicals and physical agents, the reproductive system has remarkable reslience to insult, with most insults being of
to the
only a transitory nature. John A Thomas University
1 Bouma MJ, van der Kaay HJ. Epidemic malaria in India and the El Niño Southern Oscillation. Lancet 1994; 344: 1638. 2 Tyagi BK. Distribution of arthropod vector-borne communicable diseases and control of their vectors in India. Indian Rev Life Sci 1994; 14: 223-43. 3 Tyagi BK, Verma KVS. Anopheline mosquitoes of Shri Ganganagar district (Rajasthan) transmitting malaria parasite. J Appl Zool Res 1991; 2: 85-91.
Falling sperm counts SIR-It is with a great deal of professional interest that I have followed the continuing debate about falling male sperm and geographical counts, environmental oestrogens, increases in testicular cancers (see April 15, p 933). Indeed, this topic has stirred discussion, certainly in the lay press. The purported linkage between reduced male sperm counts and environmental oestrogens is both dubious and tenuous. Sperm counts are notoriously variable and subject to many physiological factors (eg, age, frequency of ejaculation, seasonal changes, &c), concurrent illness, and even in It differences collection techniques. is highly doubtful that so-called environmental oestrogens have an important role in the search for candidates that might cause insult to the male reproductive system. The exposure levels of environmental pollutants that might have weak oestrogenic properties show little relevance to those doses or actions arising from female sex hormones, whether from physiological sources or therapeutic indications. With respect to the purported linkage between so-called environmental oestrogens and the increasing frequency of testicular cancers, one is reminded that one of the richest sources of potent endogenous oestrogens is the male gonad. Testicular cancers, although increasing in certain countries, remain very rare. The association between in-utero stilboestrol (DES) exposure and testicular cancer as well as semen quality (eg, Eliasson Score) is controversial. A paradox is also shown by the cancer-protecting properties of the phyto-oestrogens, as shown by the reduced occurrence of prostate gland
neoplasms. Contrary to your editorial, far more is known about male reproductive toxicants than female reproductive toxicants. The male reproductive system is simpler to study and subject to fewer physiological changes than the female Of course, the system. occupational hazard of dibromochloropropane (DBCP) well documented as a male sterilant. Aside from neurotoxic agents (eg, organophosphates) and the adverse effects that may accompany certain cardiovascular drugs causing impotence (sometimes referred to as the Devonshire droop), the environmental pollutants deemed more toxic to the mammalian gonad are in fact heavy metals (eg, lead, mercury, cadmium, and cobalt). Ironically, platinum is perhaps one of the more selective male gonadal toxins whose therapeutic usefulness resides in the treatment of testicular cancers.
Endocrine
ranging from
disruptions can be seen in many conditions, natural goitrogens and nutritional deficiencies
of Texas Health Science
Centre, San Antonio, TX 78284, USA
Micronutrition SIR-The publication of not one but two research papers on micronutrient deficiencies is cause for great rejoicing by those who have struggled to overcome the block usually encountered to this subject with medical colleagues. The reports to which I refer are those by Pee and colleagues (July 8, p 75) and Naurath and co-workers (July 8, p 85). The Pee study proves the point that in multiparous Javanese women an apparently adequate dietary intake of a vitamin or provitamin-vitamin A and beta-carotene in this case-may not be sufficient to achieve normality, and more bioavailable supplements may be required. In Naurath’s report the point is well made that the presence of accepted normal serum concentrations of the vitamins studied does not ensure their optimum function in elderly people. This principle certainly applies, in any age group, to magnesium (technically, not a micronutrient) for which white cell concentrations are a more reliable guide to tissue concentrations than are those in plasma. A third paper by van de Wielen and colleagues (July 22, p 207) on serum vitamin D concentrations among elderly people in Europe shows that inadequate levels of vitamin D can occur during the winter in this age group, irrespective of latitude. This will
surprise to many people. A fundamental point not made in these three reports is that micronutrient substances given alone may be inappropriate, multiple deficiencies usually being the rule. The proper use of one micronutrient may depend on the presence of others in correct amounts. Some examples are well known, but others remain to be proven. There is much understandable resistance to these ideas but, now that the subject of micronutrition has come of age in orthodox medicine, we can look forward to real progress. Anyone who has witnessed the astonishing benefits of appropriate micronutrient supplementation will know how important research in this subject is both for ourselves and the less developed world.
come as a
R J Walden 5 Bron Court,
Brondesbury Road,
London NW6 5AU, UK
Treatment of Pott’s disease in countries
developing
SiR-In his July 29 commentary (p 264), Miller draws attention to Pott’s paraplegia. In industrialised countries, with the re-emergence of tuberculosis due to the spread of HIV, drug abuse, and population migration, spinal tuberculosis (the most common form of skeletal seems on its way to becoming a public health tuberculosis’) problem. However, developing countries have to combat spinal tuberculosis all the time. The enormous cost of surgery and long chemotherapy for a country whose resources are inadequate is another difficulty in providing effective management of the disease. Thus, although one has 635
Tyagi, R C Chaudhary, S P Yadav
Desert Medicine Research Centre, PO Box 122,
Jodhpur 342005, India
therapeutic use of oestrogens in both males and females. It is important to keep in mind that the relation between falling male sperm counts and environmental oestrogens is a hypothesis with little or no scientific bias. Despite the perturbations of the endocrine system by various chemicals and physical agents, the reproductive system has remarkable reslience to insult, with most insults being of
to the
only a transitory nature. John A Thomas University
1 Bouma MJ, van der Kaay HJ. Epidemic malaria in India and the El Niño Southern Oscillation. Lancet 1994; 344: 1638. 2 Tyagi BK. Distribution of arthropod vector-borne communicable diseases and control of their vectors in India. Indian Rev Life Sci 1994; 14: 223-43. 3 Tyagi BK, Verma KVS. Anopheline mosquitoes of Shri Ganganagar district (Rajasthan) transmitting malaria parasite. J Appl Zool Res 1991; 2: 85-91.
Falling sperm counts SIR-It is with a great deal of professional interest that I have followed the continuing debate about falling male sperm and geographical counts, environmental oestrogens, increases in testicular cancers (see April 15, p 933). Indeed, this topic has stirred discussion, certainly in the lay press. The purported linkage between reduced male sperm counts and environmental oestrogens is both dubious and tenuous. Sperm counts are notoriously variable and subject to many physiological factors (eg, age, frequency of ejaculation, seasonal changes, &c), concurrent illness, and even in It differences collection techniques. is highly doubtful that so-called environmental oestrogens have an important role in the search for candidates that might cause insult to the male reproductive system. The exposure levels of environmental pollutants that might have weak oestrogenic properties show little relevance to those doses or actions arising from female sex hormones, whether from physiological sources or therapeutic indications. With respect to the purported linkage between so-called environmental oestrogens and the increasing frequency of testicular cancers, one is reminded that one of the richest sources of potent endogenous oestrogens is the male gonad. Testicular cancers, although increasing in certain countries, remain very rare. The association between in-utero stilboestrol (DES) exposure and testicular cancer as well as semen quality (eg, Eliasson Score) is controversial. A paradox is also shown by the cancer-protecting properties of the phyto-oestrogens, as shown by the reduced occurrence of prostate gland
neoplasms. Contrary to your editorial, far more is known about male reproductive toxicants than female reproductive toxicants. The male reproductive system is simpler to study and subject to fewer physiological changes than the female Of course, the system. occupational hazard of dibromochloropropane (DBCP) well documented as a male sterilant. Aside from neurotoxic agents (eg, organophosphates) and the adverse effects that may accompany certain cardiovascular drugs causing impotence (sometimes referred to as the Devonshire droop), the environmental pollutants deemed more toxic to the mammalian gonad are in fact heavy metals (eg, lead, mercury, cadmium, and cobalt). Ironically, platinum is perhaps one of the more selective male gonadal toxins whose therapeutic usefulness resides in the treatment of testicular cancers.
Endocrine
ranging from
disruptions can be seen in many conditions, natural goitrogens and nutritional deficiencies
of Texas Health Science
Centre, San Antonio, TX 78284, USA
Micronutrition SIR-The publication of not one but two research papers on micronutrient deficiencies is cause for great rejoicing by those who have struggled to overcome the block usually encountered to this subject with medical colleagues. The reports to which I refer are those by Pee and colleagues (July 8, p 75) and Naurath and co-workers (July 8, p 85). The Pee study proves the point that in multiparous Javanese women an apparently adequate dietary intake of a vitamin or provitamin-vitamin A and beta-carotene in this case-may not be sufficient to achieve normality, and more bioavailable supplements may be required. In Naurath’s report the point is well made that the presence of accepted normal serum concentrations of the vitamins studied does not ensure their optimum function in elderly people. This principle certainly applies, in any age group, to magnesium (technically, not a micronutrient) for which white cell concentrations are a more reliable guide to tissue concentrations than are those in plasma. A third paper by van de Wielen and colleagues (July 22, p 207) on serum vitamin D concentrations among elderly people in Europe shows that inadequate levels of vitamin D can occur during the winter in this age group, irrespective of latitude. This will
surprise to many people. A fundamental point not made in these three reports is that micronutrient substances given alone may be inappropriate, multiple deficiencies usually being the rule. The proper use of one micronutrient may depend on the presence of others in correct amounts. Some examples are well known, but others remain to be proven. There is much understandable resistance to these ideas but, now that the subject of micronutrition has come of age in orthodox medicine, we can look forward to real progress. Anyone who has witnessed the astonishing benefits of appropriate micronutrient supplementation will know how important research in this subject is both for ourselves and the less developed world.
come as a
R J Walden 5 Bron Court,
Brondesbury Road,
London NW6 5AU, UK
Treatment of Pott’s disease in countries
developing
SiR-In his July 29 commentary (p 264), Miller draws attention to Pott’s paraplegia. In industrialised countries, with the re-emergence of tuberculosis due to the spread of HIV, drug abuse, and population migration, spinal tuberculosis (the most common form of skeletal seems on its way to becoming a public health tuberculosis’) problem. However, developing countries have to combat spinal tuberculosis all the time. The enormous cost of surgery and long chemotherapy for a country whose resources are inadequate is another difficulty in providing effective management of the disease. Thus, although one has 635