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Biomedical subjects

B S Hetzel

Publications and source records attributed to B S Hetzel.

At least 19 recordsLinked to original sources
PubMed2000

Iodine and neuropsychological development.

The establishment of the essential link among iodine deficiency, thyroid function and brain development has emerged from a fascinating combination of clinical, epidemiologic and experimental studies. The central human phenomenon that focuses this relationship is the condition of endemic cretinism, described from the Middle Ages and characterized in its fully developed form by severe brain damage, deaf mutism and a spastic state of the hands and feet. The demonstration of the prevention of cretinism in a double-blind controlled trial with injections of iodized oil in Papua New Guinea (1966-1970) established the causal role of iodine deficiency in cretinism by an effect on the developing fetal brain. Cretinism could not be prevented unless the iodized oil was given before pregnancy. Iodine deficiency is now regarded by the WHO as the most common preventable cause of brain damage in the world today, with at least 30 million suffering from this preventable condition. Since 1986 the international NGO, the International Council for Control of Iodine Deficiency Disorders, has worked closely as an expert group with WHO and UNICEF in assisting countries with a program of universal salt iodization for the elimination of iodine deficiency as a cause of brain damage by the year 2000. In 1996, WHO reported that 56% of the population of 83 developing countries now had adequate access to iodized salt. This represents an increase of 750 million since 1990 with protection of 12 million children.

Brain↗
PubMed1996

Iodine deficiency: a global problem.

The United Nations and other international organisations, in cooperation with national governments, aim to eliminate this major cause of fetal brain damage by the year 2000.

Global Health↗
PubMed1990

Communication and health--health as an ecosystem.

The importance of communication in public health is described with reference to recent experiences in Australia where good progress has been made with certain major public health problems. There has been a 30% fall in road accident deaths and a 40% fall in deaths from coronary heart disease, and a smoke free environment has been established in public places and in the work place. These successes depended on effective communication based on appropriate data. Evaluation data have also been used to keep the public informed and to reinforce the message. The cooperation of the media has been most important in stimulating a new awareness of health and the opportunities for self help and community initiatives. In central Australia, new initiatives involving the Central Australian Aboriginal Congress have led to an improvement in the health of Aborigines, the training of Aborigines as health workers and the development of a Centre for Appropriate Technology at the Alice Springs College of Technical and Further Education. At the international level, Australia sponsored a World Health Assembly resolution in 1986 calling for the elimination of iodine deficiency disorders. With the support of the Australian International Development Assistance Bureau and the United Nations Children's Fund (UNICEF), an international expert group of scientists and public health professionals, the International Council for Control of Iodine Deficiency Disorders (ICCIDD), based in Adelaide, has been able to work with the World Health Organization (WHO) and UNICEF in the development of an international public health programme aimed at eliminating iodine deficiency disorders by the year 2000. The ICCIDD is a new model for communication and action in international health which is now being advocated for other areas.

Breath Tests↗
PubMed1989

Fall in coronary heart disease mortality in U.S.A. and Australia due to sudden death: evidence for the role of polyunsaturated fat.

Epidemiological studies have been reviewed which provide suggestive evidence of an association between the fall in coronary heart disease mortality in the U.S.A and Australia since 1967, characterized by a fall in sudden deaths, to the increase in polyunsaturate fat consumption that has occurred in both countries since 1960. This association led directly in the same institution to carefully designed experimental studies undertaken in the rat, and a non-human primate, the marmoset (Callithrix jacchus jacchus) with a heart and lipid metabolism more closely resembling that of man. In both animal species, a vegetable fat diet had a protective effect against the increase in contractility of isolated papillary muscles induced by age, the addition of animal fat, or by isoprenaline in vitro. Similar effects were observed following coronary artery ligation, where the extent of dysrhythmia was greatly reduced by supplementing the diet with a linoleic acid rich vegetable oil. It is concluded that the combination of epidemiological and experimental evidence indicates a protective effect of dietary polyunsaturates against sudden cardiac death. This work illustrates the value of the integration of epidemiological and experimental approaches to the aetiology of disease.

Animals↗
PubMed1989

A review of experimental studies of iodine deficiency during fetal development.

Iodine deficiency is now recognized as a major international public health problem. It is estimated that 800 million people may be at risk of the effects of iodine deficiency. In humans, the effects occur at all stages of development: the fetus, the neonate, the child and adult. The effects are now denoted by the term iodine deficiency disorders (IDD). They include miscarriages, stillbirths, congenital anomalies, as well as the more familiar goiter, cretinism, impaired brain function, and hypothyroidism in children and adults. In domestic animals, reproductive failure has been reported with the production of aborted, stillborn and weak calves. Experimental studies in animal models have been reviewed to provide evidence of the mechanisms involved, particularly in relation to brain development. The findings in three different species (rat, sheep, monkey) indicate that the effects are mediated by a combination of maternal and fetal hypothyroidism, the effect of maternal hypothyroidism being earlier than the onset of fetal thyroid secretion. The findings suggest that iodine deficiency has an early effect on neuroblast multiplication and, if so, this could be important in the pathogenesis of the neurological form of endemic cretinism. The assessment of the full effects of iodine deficiency on the brain requires further studies in the postnatal period to determine the duration of these effects.

Animals↗
PubMed1989

The effect of thyroxine, 3, 5-dimethyl-3'isopropyl-L-thyronine and iodized oil on fetal brain development in the iodine-deficient sheep.

Studies have been carried out to investigate the role of maternal and fetal thyroid function in the effects of iodine deficiency on fetal brain development in sheep. Iodine deficiency was established with an especially prepared low-iodine diet of maize and pea pollard. The iodine-deficient sheep were mated and the end of the second trimester of pregnancy (100 days gestation) were divided into groups which received either a sc injection of T4 or 3,5-dimethyl-3-isopropyl-L-thyromine or an injection of iodized oil. AT 140 days gestation (10 days prior to parturition) comparison of the fetuses delivered by hysterotomy revealed that the retarded fetal brain development observed in iodine deficiency was greatly improved by T4 and by iodized oil. However, T4 and iodized oil failed to correct the reduction in the number and the increase in the length of synaptic appositions which were observed in the fetal cerebral cortex after iodine deficiency. In addition, the histological appearance of the fetal thyroid gland and the levels of plasma thyroid hormones were restored to normal. The administration of 3,5-dimethyl-3'-isopropyl-L-thyronine had no effect on the retarded fetal brain and body development of the iodine-deficient fetuses. The lack of response may be due to the ability of 3,5-dimethyl-3'-isopropyl-L-thyronine to cross the ovine placenta as no reduction in the abnormally elevated fetal plasma TSH observed in spite of a fall in maternal plasma TSH and apparent restoration of maternal thyroid function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Fetal brain development in response to iodine deficiency in a primate model (Callithrix jacchus jacchus).

The common cotton-eared marmoset (Callithrix jacchus jacchus) has been used for the first time as a primate model to study the effects of dietary iodine deficiency on fetal brain development. Paired male and female marmosets were fed a low-iodine diet of maize, peas, meat meal, Torula yeast, maize oil and added vitamins, minerals and amino acids for 6 months before mating. Offspring from first and second pregnancies were compared with offspring from control marmosets fed the same diet but supplemented with iodine. Severe iodine deficiency in the fetus at birth was evident by reduced plasma thyroxine levels, increased plasma thyroid stimulating hormone levels, increased thyroid weight and reduced thyroid iodine content. Thyroid histology revealed hyperplasia, hypertrophy and absence of colloid material in the follicles. Iodine deficiency caused a reduction in the weight of the fetal brain and in particular the cerebellum. Brain cell number was reduced in the cerebellum and brainstem but cell size was reduced in the cerebral hemispheres. Histology of the brain revealed morphological changes in the cerebellum and cerebral hemispheres. In the-cerebellum there was: an increase in the thickness of the external germinal layer indicative of impaired cell acquisition; a decrease in total area; a decrease in molecular layer area; and an increase in Purkinje cell (Pc) linear density due to a reduction in the length of the Pc line. The decrease in molecular layer area and increase in Pc linear density imply diminished ascending and lateral extension of Pc dendrites. Changes in the cerebral hemispheres consisted of an increase in the density of neuronal cell bodies in the granular band and a decrease in synaptic counts in the layer between the pia mater and supragranular band of the visual cortex. Offspring from second pregnancies compared to those from first pregnancies were more severely affected and associated with lower plasma levels of maternal and fetal thyroxine. These findings indicate the importance of maternal and fetal thyroid function in relation to fetal brain development in the primate.

Animals↗