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Biomedical subjects

B S Hetzel

Publications and source records attributed to B S Hetzel.

At least 37 records · Page 2Linked to original sources
PubMed1986

The effect of maternal thyroidectomy prior to conception on foetal brain development in sheep.

Merino ewes were surgically thyroidectomized, and mated 6 weeks later when their plasma thyroxine (T4) levels were negligible. Their foetuses were delivered by hysterotomy at 52, 71, 84, 98, 125, 140 days gestation or at term (150 days). Despite the very low levels of T4 in maternal plasma, the concentrations of T4 in foetal plasma were not significantly different after 71 days gestation from those of foetuses of sham-operated (control) ewes. Foetal brain and body weights, however, were reduced from 71 days compared to those of foetuses of sham-operated ewes. The foetal brain weights but not the body weights were restored to normal from 125 days to term. In addition to the weights, cell number (DNA) and cell size (protein:DNA ratio) appeared to be normal in the neonatal brain at parturition and this was confirmed by histological examination of the brains. Thus lack of maternal thyroid hormones in early pregnancy may cause a reduction in brain and body growth in the foetus which, in the case of the brain, appears to be restored to normal after the onset of foetal thyroid function.

Animals↗
PubMed1985

Low-iodine diet for the production of severe I deficiency in marmosets (Callithrix jacchus jacchus).

A low-iodine diet consisting of maize, peas (Pisum sativum), torula yeast, meat meal, maize oil and added vitamins, minerals and amino acids was given to eight pairs of adult, common cotton-eared marmosets (Callithrix jacchus jacchus). Eight control pairs were given the same diet to which potassium iodate was added. Both groups also received low-I apple and deionized water. The diet provided adequate nutrition, as confirmed by the maintenance of body-weight and good health. In the I-deficient marmosets the concentration of plasma thyroxine was decreased from 140.1 nmol/l to 22.4 nmol/l and thyroid-stimulating hormone increased significantly from 1.8 ng/ml to 9.0 ng/ml compared with control marmosets, thereby indicating severe I deficiency. Compared with newborn offspring from control marmosets, the thyroid glands from the I-deficient offspring showed an increase in weight, a decrease in I content and, on histological examination, hyperplasia, hypertrophy and a total absence of colloid material in the follicles.

Animals↗
PubMed1984

Restoration of brain growth in fetal sheep after iodized oil administration to pregnant iodine-deficient ewes.

Iodized oil was administered as a single intramuscular injection to pregnant iodine-deficient ewes at 100 days gestation and the subsequent growth of their fetuses compared with that of fetuses of severely iodine-deficient ewes and of iodine-replete ewes, all of which were fed the same low-iodine diet. The administered iodine produced a remarkable improvement in thyroid function and physical appearance of the fetuses, accompanied by an increase in brain growth and to a lesser extent in body growth, which at 140 days was only slightly (but significantly) less than that of the controls. There was restoration of the number of cells (DNA) and myelination (cholesterol/DNA) in the cerebellum and cerebral hemispheres which suggests a catch-up of neuroblast development during pregnancy. Histological examination, however, revealed that counts of synapses (density) in the cerebral cortex after iodized oil were still less than those of the control fetal brains. The relevance of these findings to the effects of iodine deficiency on human brain development is discussed.

Animals↗
PubMed1983

Iodine deficiency disorders (IDD) and their eradication.

Disorders resulting from severe iodine deficiency affect more than 400 million people in Asia alone. These disorders include stillbirths, abortions, and congenital anomalies; endemic cretinism, characterised most commonly by mental deficiency, deaf mutism, and spastic diplegia and lesser degrees of neurological defect related to fetal iodine deficiency; and impaired mental function in children and adults with goitre associated with subnormal concentrations of circulating thyroxine. Use of the term iodine deficiency disorders, instead of "goitre", would help to bridge the serious gap between knowledge and its application. Iodised salt and iodised oil (by injection or by mouth) are suitable for the correction of iodine deficiency on a mass scale. A single dose of iodised oil can correct severe iodine deficiency for 3-5 years. Iodised oil offers a satisfactory immediate measure for primary care services until an iodised salt programme can be implemented. The complete eradication of iodine deficiency is therefore feasible within 5-10 years.

Adolescent↗
PubMed1983

An investigation of the effects of daily physical activity on the health of primary school students in South Australia.

Studies of the health effects of a daily physical activity programme have been carried out in 10-year-old school children in Adelaide, South Australia. In the first phase (1978) observations on endurance fitness, four skin folds, blood pressure and blood lipids were made before and after a randomized trial over a period of 14 weeks. Comparisons were made on over 500 children drawn from classes in seven Primary schools involved in an endurance fitness programme (1 1/4 hours per day), a skill programme and the previous physical education programme (controls). The fitness group experienced significant gains in physical work capacity (PWC) and showed significant decreases in body fat compared to the other two groups. No significant differences were observed in plasma cholesterol, triglycerides and HDL cholesterol. Subsequently in the second phase (1980) observations were made on a group of 216 10-year-old children who had already experienced two years of the physical activity programme adopted after phase one. Comparison with the observations in the 10-year-old children in 1978 made prior to the intervention revealed significantly smaller skin folds and greater PWC, with lower blood pressure reaching statistical significance for diastolic pressure in boys. The findings suggest beneficial effects on health of daily physical activity programmes within existing primary school curricula. There was no evidence of any loss of academic performance as measured by arithmetic and reading tests in spite of 45-60 minutes' loss of formal teaching time each day.

Australia↗
PubMed1981

Iodine deficiency and brain development in the rat.

An assessment was made of the influence of low-iodine diet on somatic and brain development at birth (day 0) and 21 days postnatally in the rat. The rat mothers were proven to be iodine-deficient by assay of plasma thyroxine and thyroid stimulating hormone prior to mating, an at 21 days postnatally, when maternal thyroids were removed, weighed and stored for subsequent iodine analysis, along with those of the offspring. There were no significant differences in body weight or brain weight of the offspring at birth, or in the content of DNA or protein. However, at 21 days there was a significant reduction in body weight (21.7%) and whole brain weight (7.9%, P less than 0.2) which was associated with a significant fall n cholesterol content (12.4%, P less than 0.05) and protein level (9.6 %, P less than 0.01), while DNA was not significantly affected (6%). The greatest reduction in weight was seen in the cerebellum. The thyroids in these rats were double normal size, showed follicular cell hypertrophy and absence of colloid histologically, and contained 8% of the iodine content of controls. It is concluded that iodine deficiency retards both somatic and brain development, the change in the latter case being expressed as a reduction in cell size in the cerebral hemispheres and cerebellum, along with reduced myelination throughout the brain.

Animals↗
PubMed1981

The effect of ethanol and acetaldehyde on DNA synthesis in growing cells and on fetal development in the rat.

Incorporation of 3H-thymidine into DNA was significantly diminished by treatment with ethanol and acetaldehyde in regenerating rat liver, rat cells in culture, and rat fetal tissues. Reduced incorporation was especially marked in the fetal central nervous system and was observed with both compounds at levels similar to those reported to occur in human alcoholics. The reduced incorporation of 3H-thymidine into fetal DNA, together with the increased fetal mortality observed in dams treated specifically with acetaldehyde during pregnancy, suggests that acetaldehyde is implicated in the mechanism of teratogenesis associated with the fetal alcohol syndrome.

Acetaldehyde↗
PubMed1980

Experimental production of growth retardation in the sheep fetus after exposure to alcohol.

The effect of excessive alcohol consumption during pregnancy on fetal development has been studied in sheep. Fetuses of ewes which had consumed 10% ethanol in water before, and during, pregnancy were delivered by hysterotomy 10 days before parturition and found to be shorter (P < 0.01), lighter (P < 0.01), and to have significantly lighter brains (P < 0.05) than normal fetuses of comparable gestational age. Heart, liver, spleen, kidneys and adrenal glands all weighed less than those of fetuses from ewes which drank water instead of alcohol. The findings provide experimental evidence for growth retardation after exposure of the sheep fetus to alcohol, and are consistent with clinical reports on the human fetal alcohol syndrome.

Animals↗
PubMed1980

Low-iodine diet for producing iodine deficiency in rats.

A low-iodine diet has been prepared for rats, using locally available low-iodine ingredients. On analysis it has been shown to consistently contain 15-20 ng iodine/g. When fed to growing female rats, this diet produced severe iodine deficiency while not significantly affecting growth or reproduction. The deficiency was manifested by a fall in daily urinary iodine excretion (to less than 1 microgram/day) and a seven-fold increase in thyroid uptake (131I) observable within 3 months. Levels of plasma thyroxine (T4) and thyroid stimulating hormone (TSH) continued to change for 4-5 months, T4 falling from 69.9 to 7.5 nmol/l and TSH increasing seven-fold from a control value of 364 to 2406 ng/ml. Goitre was present in all iodine-deficient rats and iodine content in the thyroid was 10% of the control value.

Animal Feed↗
PubMed1980

A comparison of trends of coronary heart disease mortality in Australia, USA and England and Wales with reference to three major risk factors-hypertension, cigarette smoking and diet.

A comparison has been made of the recent changes in coronary heart disease mortality in Australia, the USA, and in the United Kingdom (England and Wales). Sharp declines in mortality dating from 1966 in Australia and from 1968 in the USA in both sexes contrast with a persistent increase in men in England and Wales until 1972 (after which a sight fall occurred) and a consistent slight fall in women since 1950. An investigation has been made of changes in 3 major risk factors-hypertension, cigarette smoking and diet in the 3 countries in an attempt to determine to what extent such changes might correlate with the different patterns of mortality. There has been a progressive and similar fall in mortality due to hypertension in both sexes in all 3 countries since 1950. There was a rise in cigarette smoking in all 3 countries from 1947 followed by a fall in the USA from 1963 and a more recent fall in men in Australia. There has been a levelling off of smoking in the United Kingdom in middle-aged and older men but not in women where smoking rates have increased from 1950 since when there has been a progressive slight fall in overall coronary heart disease mortality (although there is evidence of a recent rise in younger women.) Changes in dietary constituents (meat, eggs, milk and cheese, butter or margarine) have been examined by reference to aggregate consumption data. In Australia and the USA increases in vegetable fat consumption have occurred since 1950 with a reduction in animal fat in Australia but not in the USA. In the United Kingdom increases in vegetable fat have not been observed while there has been some increase in animal fat. It is concluded that the different patterns of coronary heart disease mortality in the 3 countries do correlate to some extent with changes in diet and cigarette smoking.

Adult↗
PubMed1980

Production of severe iodine deficiency in sheep using a prepared low-iodine diet.

Extensive tests on dietary materials suitable for ingestion by sheep have led to the preparation of an appropriate diet which, when fed to the sheep, caused severe iodine deficiency. The deficiency was manifested by daily urinary excretion values which fell to levels of less than 20 micrograms iodine and by thyroxine (T4) and triiodothyronine (T3) concentrations in blood plasma which were reduced from more than 90 and 1.80 nmol/l to the low levels of less than 2.58 and 0.31 nmol/l respectively. The values were attained 5 months after feeding the low-iodine diet. Goitre was present in most of the animals and the reductions in T4 and T3 values were accompanied by increased concentrations of plasma thyroid stimulating hormone (TSH) from less than 8.6 to more than 68 ng/ml. Samples of wool removed from selected areas of the sheep showed that the iodine-deficient diet also caused a reduction in the growth of wool.

Animals↗
PubMed1979

Fetal iodine deficiency and motor performance during childhood.

Motor performance of children born to mothers living in an iodine-deficient region was assessed. The mothers were participants in a controlled trial of intramuscular iodised oil in the prevention of endemic cretinism carried out in the Western Highlands of Papua New Guinea. Mothers received either iodised oil or placebo saline. Children born to mothers given iodine were significantly faster and more accurate in tests of manual function than children from control mothers. The findings indicate that iodine deficiency may lead to a spectrum of subclinical deficits which place the children at a developmental disadvantage.

Child↗