Marjorie Dunlop

Hypertension in childhood obesity.

Blood pressure has been measured in 209 children on first consultation when referred to the Obesity Research Clinic. Blood pressure correlated with estimates of obesity made by subscapular‐skinfold thickness, and calculations of per cent body weight as fat. Neither age nor duration of the obesity showed significant correlation with the blood pressure.

Effects of Maternal Caffeine Ingestion on Neonatal Growth in Rats

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.

The Growth and Development of Fat Cells in Infancy

Summary: 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 μm 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.Speculation: Previously unrecognized cells in fetal and infant fat tissue may represent the precursors of mature adipose cells. Establishment of adipose tissue occurs with the development of such cells and the gradual accumulation of fat within the cell until the age of 6–12 months postnatally.

Lipogenesis in developing human adipose tissue.

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.

Endogenous ionophoretic activity in the neonatal rat pancreatic islet

Recent studies have focused attention on the ability of the pancreatic P cell to regulate the transposition of Ca2+ during stimulus recognition and the coupling of this to insulin release [1,2]. Some exogenous agents with an insulinotrophic effect may alter the ionophoresis of Ca2+ through processes involving native, endogenous ionophores 131, possibly derived from membrane phospholipids [4-71. and liposomes. The multilayered membranes formed in phospholipid-impregnated Millipore filters have been used extensively to investigate the structural, physio-chemical and electrical properties of phospholipid bilayers [13-161. As ionophoresis could be expected through these membranes, the procedure was adapted to investigate the ability of pancreatic extracts to translocate Ca2+ across an intact lipid layer between 2 aqueous compartments.

Fasting plasma glucose in children

Fasting plasma glucose levels were measured in samples taken preoperatively in 116 patients, it was found that mean plasma glucose levels increased with age and that there was no relationship between the period of fasting and plasma glucose concentrations. Fewer children had levels below 3 mmols/l than in other reported series.

Plasma lipid values and lipoprotein patterns during adolescence in boys

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.

Methylxanthine effects on cyclic adenosine 3′:5′ monophosphate phosphodiesterase activity in preparations of neonatal rat cerebellum: Modification by trifluoperazine

Abstract Paradoxically, caffeine was found to stimulate the activity of 3′:5′-cyclic AMP phosphodiesterase at substrate concentrations of 14μM, in cerebellar tissue from 10-day-old rats. Pretreatment with trifluoperazine, an inhibitor of calmodulin-dependent enzyme activation, converted the stimulatory effect of caffeine to the expected inhibitory action. Trifluoperazine pretreatment also increased the inhibitory action of theophylline on the cerebellar phosphodiesterase, but had no effect on the inhibitory action of 3-isobutyl-1-methylxanthine. It is suggested that caffeine and to a lesser extent theophylline in addition to their intrinsic phosphodiesterase inhibitory activity can also cause calmodulin dependent effects on cerebellar phosphodiesterase due to calcium mobilisation.

Growth and Development of Fat in Adolescent School Children in Victoria Part 1. Normal Growth Values and Prevalence of Obesity

Court, J. M., Dunlop, Marjorie, Reynolds, M., Russell, J. and Griffiths, Leonie (1976). Aust. paediat. J., 12, 296–304. Growth and development of fat in adolescent school children in Victoria. Part I. Normal growth values and prevalence of obesity.

Identification of small cells in fetal and infant adipose tissue.

Summary: In developing adipose tissue, cells of size less than 25 μm 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 μm. Their modal cell size was remarkably constant in fetuses and in 2-month-old and 22-month-oId 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.Speculation: Developing adipose tissue in the fetus and young infant contains small cells that may represent differentiated fat cells. The recognition of these cells may be important in any study of adipose tissue development during periods of cell replication.