Biomedical subjects
Publications and source records attributed to M Dunlop.
Explore the source record for details and available documents.
The aim of this study is to evaluate the short term effect of naturally occurring dietary fibre (mainly cellulose and hemicelluloses) in the Western diet on carbohydrate absorption. Two equicaloric test meals were designed, each containing the same amount and types of absorbable carbohydrate and similar proportions of fat and protein. One meal was composed of salad vegetables and apple and the other of simple sugars and starch added to a gelatine and cream cheese base. Thirteen normals and 12 maturity onset diabetics consumed both test meals and neither group showed any reduction in the post-prandial blood glucose levels or immunoreactive insulin concentrations on the fibre containing meal. Thus naturally occurring dietary fibre in unrefined foods commonly consumed in Australia does not attenuate carbohydrate absorption in short term studies.
When caffeine (1,3,7-trimethylxanthine) was introduced into the diet of rats throughout pregnancy and lactation at levels of consumption of 10 mg/kg/day, offspring of successive pregnancies showed growth reductions. This finding was not accompanied by teratogenic effects. However, following four pregnancies severely reduced offspring growth and neonatal mortality was demonstrated. The birthweights of these offspring were 72.5% of control. This study mimicked the mode of intake and quantities of caffeine consumed in many societies.
Reduced offspring growth was found following introduction of caffeine into the normal diet of rats during pregnancy and lactation. When maternal caffeine (10 mg/kg/day) was consumed together with supplementary sucrose (7 g/kg/day) the expected offspring growth reduction attributed to caffeine did not occur. It is concluded that maternal nutritional status may determine the outcome of caffeine exposure at low concentrations which mimic human usage.
De novo lipid synthesis can be demonstrated in human fetal subcutaneous tissue cells which are in the initial stages of liquid accumulation. Lipogenic capacity measured as ability to incorporate acetate into neutral lipid was shown to increase with gestational age. This lipogenic capacity was accompanied by an increased activity of acetyl co-enzyme A carboxylase. Insulin, which is known to activate this enzyme in mature adipose tissue, increased neutral lipid synthesis in fetal subcutaneous tissue. When tissue insulin levels were determined, insulin was found from 16 wk gestation. At this time triglyceride content of the tissue was also increasing. Thus de novo fatty acid synthesis is a means by which the developing adipose cell initiates lipid accumulation.
Explore the source record for details and available documents.
In developing adipose tissue, cells of size less than 25 micron may make a major contribution to adipose tissue cell populations. This study reports the separation, identification, and sizing of infant and foetal adipose tissue small cells. Subcutaneous adipose tissue was taken from the anterior abdominal wall of children aged 2 months and 22 months. Subcutaneous tissue was also obtained from a paraumbilical site in 4 fetuses of gestational age 16 weeks. Tissue samples were fixed in buffered osmium tetroxide solution containing collidine. Aliquots of cell preparations suspended in saline on microscope slides were viewed and separated using a dissecting microscope. A diameter distribution of particle size was obtained using at least 200 cells for each preparation. There was a substantial number of cells that were smaller than 20 micron. Their modal cell size was remarkably constant in fetuses and in 2-month-old and 22-month-old infants. Ultrastructural studies show that the tissue is composed of a relatively uniform population of cells within sparsely collagenous connective tissue. Although some of the cells show no intracytoplasmic aggregates of lipid material, others show variable amounts of lipid material which can occupy a very large part of the cell volume.
Studies on the development of adipose tissue in infancy would seem essential to test the hypothesis that adult fat stores relate to the numbers of fat cells developed during early childhood. Thirty infants aged from 1-28 months and 13 fetuses of approximately 11-16 weeks of gestation obtained at therapeutic abortion and two preterm infants of 28 weeks of gestation were studied. The cells of both fetal and infant adipose tissue were separated from connective tissue and fixed by treatment with osmium tetroxide in buffered collidine using a method modified from Hirsch and Gallian (J. Lipid Res.,9:100(1968) for estimation of cell size and number. In fetal and early infancy there are two populations of cells in adipose tissue. Small cells found in tissue before birth and the first months of postnatal life do not contain fat. The larger cells, which are fat containing, represent maturing fat cells. They are cells which include fat cells recognized by previous workers but up to 24.6% were found to be less than 25 micron in diameter. Small cells in the early stages of fat accumulation may make an important contribution to the cell population of fat mass. It is apparent that increasing fat accumulation in the first 6-12 months of life, as demonstrated by increased skinfold thickness measurements, is associated with increasing fat cell size and that this association bears a linear relationship.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In order to provide a comprehensive account of pituitary-testicular function in man, 466 subjects, ranging in age from 2 to 101 years, were studied to examine blood levels of the pituitary gonadotrophins (LH and FSH), the sex steroids testosterone and oestradiol, the binding capacity of the sex hormone binding globulin (SHBG), the free testosterone and oestradiol fractions, and the transfer constant for the peripheral conversion of testosterone to oestradiol. The results were compared with clinical indices of testicular size, sexual function and secondary sex hair distribution. Serum LH and FSH were low before puberty, increased in pubertal adolescents to levels somewhat above those of adults and subsequently increased progressively over the age of 40 years. Testosterone levels fell slowly after the age of 40, while there was a slight rise in plasma oestradiol with increasing age. FSH and testosterone showed small seasonal variations in young adult men, the lowest values being seen in winter. SHBG binding capacity was high in two prepubertal boys, fell in adult men, but increased in old age. Free testosterone and oestradiol levels fell in old age. The metabolic clearance rates (MCR) of testosterone and oestradiol also fell in old age, while the conversion of testosterone to oestradiol was increased. Many correlations were observed between various hormonal and clincial measurements. The evidence is consistent with a primary decrease in testicular function over the age of 40 years.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Lipid studies were performed on fasting plasma samples in 214 healthy adolescent boys, 11-19 years of age. Ranges of normal values for plasma cholesterol and triglyceride concentrations, and normal lipoprotein patterns were established for this age group. The boys were grouped according to puberty rating. A significant increase in triglyceride values was obtained with adolescent maturity. Plasma cholesterol values did not change with age or puberty rating. One boy had hypercholesterolemia and a lipoprotein pattern consistent with Type II hyperlipoproteinemia (Fredrickson). Seventeen boys, all of whom had reached adolescent maturity, had elevated triglyceride values and a marked increase in pre-beta-lipoprotein. It appears from this study that increased concentrations of triglyceride and Type IV hyperlipoproteinemia of Fredrickson may be detected as boys reach maturity at adolescence.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.