PubMed Health⌕ Search

Biomedical subjects

M C Elphick

Publications and source records attributed to M C Elphick.

At least 19 recordsLinked to original sources
PubMed1984

Transfer of fatty acid across the cat placenta.

The transfer of fatty acids across the placenta was investigated in six anaesthetised pregnant cats at 60 days gestation (term 64-66 days). 1-14C palmitic acid bound to albumin was infused for 20 min and blood samples taken from a maternal artery and the umbilical vessels of the fetuses as they were delivered serially by Caesarean section either during and immediately after the infusion. Fetal blood and organs were analysed with respect to fatty acid content and presence of labelled fatty acid. The maternal and fetal plasma free fatty acid concentrations were 0.32 +/- 0.02 and 0.18 +/- 0.02 mmol/L (mean +/- SE) respectively. There was no significant umbilical v-a difference and no correlation between maternal and fetal concentrations. The specific activity of labelled palmitic acid in the fetal circulation was less than 1% of that in the maternal circulation but there was a very small but significant umbilical v-a difference during the infusion. The percentage composition of arachidonic acid in maternal plasma free fatty acid was 4.0%; in fetal plasma free fatty acid 5.8%; in fetal plasma triacylglycerol 1.9%; in fetal adipose tissue triacylglycerol 0.6%, and in fetal brain total fatty acids 12.9%. It is concluded that in the cat fatty acids do not pass freely from the maternal free fatty acid to the fetal free fatty acid compartment. It is suggested that as arachidonic acid forms a higher fraction of fetal than of maternal plasma free fatty acid and as the cat tissues are unable to convert linoleic to arachidonic acid, the possibility that fetal arachidonic acid is derived from maternal plasma phospholipids must be considered.

Adipose Tissue, Brown↗
PubMed1983

Nebulised therapy in acute severe bronchiolitis in infancy.

We have measured total work of breathing before and after the inhalation of water, salbutamol, and ipratropium bromide, given as nebulised solutions, in 39 studies on 25 infants with acute, severe bronchiolitis. Twenty minutes after nebulised water, mean work of breathing per minute was increased by 4% and work per litre by 10% with 2 infants having significant improvement and 2 others showing deterioration. After salbutamol, mean work of breathing per minute showed a 22% increase and work per litre a 0.5% rise. The condition of only one child improved by greater than 25% after this drug. Ipratropium bromide led to significant improvement in 6 out of 15 studies and no corresponding deterioration. The group results showed a fall in work of breathing, 18% in work per minute and 16% in work per litre.

Acute Disease↗
PubMed1983

Effect of maternal diet during late pregnancy on fetal lipid stores in rabbits.

Pregnant rabbits were fed on a standard laboratory diet enriched with either 5-6% coconut oil or 6-7% corn oil for the last three or last six days of pregnancy. Control rabbits were maintained on the standard laboratory diet. Maternal and newborn plasma concentrations of free fatty acid, triacylglycerol and phospholipid and the profile of their fatty acids were measured. The fatty acid composition of newborn brown adipose tissue, white adipose tissue and liver was analysed. Raised levels of lauric and myristic acids in does on the coconut oil enriched diet and of linoleic acid in does on the corn oil enriched diet were found in maternal and newborn plasma free fatty acids and triacylglycerols when compared to control rabbits. The proportion of lauric and myristic acids found in the tissues of newborn from does on the coconut oil enriched diet and the proportion of linoleic acid found in the tissues of newborn from does on the corn oil enriched diet were substantially increased when compared to control newborn. Newborn adipose stores reflected the change in maternal dietary fatty acid composition when the doe had been fed an oil enriched diet for only three days favouring the view that maternal triacylglycerol could be a major source of fetal lipids.

Adipose Tissue↗
PubMed1982

Onset of thermogenesis in response to cold in newborn mice.

The onset of thermogenesis in response to cold exposure in individual mice was studied using a sensitive close circuit system for measuring their rate of oxygen consumption. On the day of birth, exposure to a cool environment did not stimulate an increase in oxygen consumption, but 48 h later the majority of mice respond by doubling their metabolic rate in response to a fall from 36 to 31 degrees C in ambient temperature. When 5 mice huddled together an ambient temperature drop from 36 to 23 degrees C was required to provoke the same response. Brown adipose tissue is present at birth but the cells are relatively small and contain little fat. By the second day they are three times larger and contain far more fat. The onset of thermogenesis appears to await the development of brown adipose tissue.

Adipose Tissue, Brown↗
PubMed1982

Lipoprotein lipase activity in human and guinea-pig placenta.

Human and guinea-pig placental activity was measured in tissue extracts and in medium in which tissue fragments have been incubated. Lipase activity was estimated from measured rates of release of 3H-labelled fatty acids from a 3H-labelled triacylglycerol substrate. Whole tissue lipase activity was 1.6 +/- 0.3 units/g (mean +/- SEM, mumol of unesterified fatty acid release/min) in the human, and 87.1 +/- 7.3 units/g in guinea-pig placental tissue. 70% of the human and 56% of the guinea-pig placental activity was lost on treating the tissues with cold acetone. Sodium chloride (0.75 M) decreased activity by 50% in extracts from both species. Lipase activity was released into media when placental fragments were incubated. The addition of heparin increased the release of lipase from human placenta but not significantly from that of the guniea-pig. Insulin had no effect on placental lipase activity from either species. It is concluded that the placentas of both species contain at least two lipases. One of these, which constituted a large of the total, had the characteristics of lipoprotein lipase.

Animals↗
PubMed1981

The effects of starvation and surgical injury on the plasma levels of glucose, free fatty acids, and neutral lipids in newborn babies suffering from various congenital anomalies.

Blood glucose, plasma free fatty acids (FFA), cholesterol, phospholipids, and triglycerides were measured in blood obtained by heel prick from 32 neonatal surgical patients suffering from various cogenital malformations which prevented and adequate intake of milk. The result of almost complete starvation for up to 7 days was investigated and the effects of a surgical operation were studied in 12 of the babies. All the babies weighed more than 2 kg at birth. A surgical operation caused a rise in blood glucose concentration but a variable change in plasma concentration of FFA. Blood glucose returned to normal within 8 to 12 hr. The plasma concentrations of cholesterol and phospholipids did not change except in two babies in whom the concentration of both fell. Four to 24 hr after operation the plasma triglyceride level fell by an average of 25% but later rose. During starvation for 7 days the blood glucose concentration was maintained within normal limits. Plasma FFA concentration normally rose during the first 2 days of life and was very high between days 3 and 5. Plasma triglyceride, cholesterol, phospholipids, and total esterified fatty acids also increased after birth. The results suggest that during starvation in the neonate there is rapid mobilisation of fat from adipose tissue stores and a reduction in the peripheral utilisation of glucose. There was no evidence to suggest any impairment of fat mobilisation or metabolism even after starvation for 7 days. After surgical injury, these changes were accentuated because the rate of utilisation of fat was greater than that of mobilisation.

Blood Glucose↗
PubMed1981

Investigation of [14C] linoleic acid conversion into [14C] arachidonic acid and placental transfer of linoleic and palmitic acids across the perfused human placenta.

In five separate experiments in which single placental lobes were perfused, [14C] antipyrine, [3H] dextran and a fatty acid mixture containing [14C] linoleic and [3H] palmitic acids were added to the maternal circuit. Samples of fetal and maternal perfusate, taken at intervals, were analysed for radioactivity and fatty acid content. The relative placental transport rates of antipyrine, linoleic and palmitic acids and the changes in maternal and fetal circuit content of linoleic, palmitic and arachidonic acids were measured. Mean transfer rates of 150, 0.023 and 0.034 mumol min-1 were obtained for [14C] antipyrine, [3H] palmitic and [14C] linoleic acids, respectively. The transfer of [3H] dextran was negligible. The transfer rates of linoleic and palmitic acids did not differ significantly from one another. The maternal circuit content of palmitic and arachidonic acids increased, whereas linoleic acid content decreased. The fetal content of all three acid increased but in the case of arachidonic and palmitic acids the increase was not as great as that seen in the maternal circuit. In no experiment was radioactivity detected in maternal or fetal perfusate arachidonic acid. It is concluded that linoleic and palmitic acids cross the placenta from the maternal to the fetal side. This transfer appears to be non-selective. The large amounts of arachidonic acid that are released into the perfusate probably originate from placental lipids other than free linoleic acid.

Antipyrine↗
PubMed1981

The development of cold-induced thermogenesis in hamsters.

The onset of the thermogenic response to cold exposure in hamsters was studied in relation to the development of brown adipose tissue. The daily weight increment of hamsters reared in animal house conditions was first determined. Organ weights in animals with body weights within +/- 1 SD of mean were obtained at intervals between 0 and 20 days of age. Adipose tissue increased rapidly in weight between days 10 and 15, but the fat content of cervical adipose tissue fell. Electronmicroscopic studies reveal that there had been a dramatic increase in the number and size of the mitochondria. Serial measurement of the rate of oxygen consumption showed an initial increase in minimal rate over the first 4 days of life followed by a larger increment from 8 to 16 days of age. On day 12 most hamsters shivered vigorously but had a poor and variable thermogenic response to cold. By day 16 all showed an impressive increase in heat production in the cold. It would appear that thermogenesis in response to cold exposure awaits the development of brown adipose tissue.

Adipose Tissue↗
PubMed1980

Plasma free fatty acid umbilical venous-arterial concentration differences and placental transfer of [14C]palmitic acid in pigs.

The passage of plasma free fatty acids across the pig placenta was investigated in four anaesthetized sows with a total of 41 fetal piglets. The plasma free fatty acid concentrations in fetal piglets were very low and appeared independent of maternal concentrations. In each piglet there was a small positive umbilical venous-arterial concentration difference. There were large differences between the composition of maternal and fetal plasma free fatty acid. The fetal free fatty acid contained relatively large amounts of arachidonic and docosahexaenoic acids. [14C]palmitic acid given intravenously to the sows appeared rapidly in fetal plasma free fatty acids but the amount of radioactivity was low. Analysis of the specific activity of palmitic acid in fetal and maternal blood indicated that little more than 10% of fatty acids coming from the placenta were derived directly from maternal plasma free fatty acids. It is concluded that, in the anaesthetized pig at Caesarean section, fatty acids enter the fetal circulation from the placenta and are taken up by the fetus at rates exceeding the requirements for structure and storage, but the major part of these free fatty acids are not derived directly from maternal free fatty acids.

Animals↗
PubMed1979

The transfer of fatty acids across the sheep placenta.

Maternal and fetal plasma concentrations of free fatty acids, triacylglycerols and phospholipids and the profile of their fatty acids were measured in three catheterized and unanaesthetized sheep. Fetal concentrations of all three lipid fractions were low and did not correlate with maternal concentrations. There were no measurable umbilical venous-arterial differences. Linoleic acid concentrations were low in both mother and fetus. The fatty acid composition of fetal adipose tissue, liver, lung and cerebellum of five animals was analysed. Again linoleic acid levels were very low, but phospholipids contained 2-8% arachidonic acid. [14C] linoleic acid and [3H] palmitic acid were infused intravenously into three ewes. Only trace amounts of labelled fatty acids were found in fetal plasma and these were confined to the free fatty acids. 14C-label was incorporated into fetal tissue lipids, but most of this probably was due to fetal lipid synthesis from [14C] acetate or other water-soluble products of maternal [14C] linoleic acid catabolism. It is concluded that only trace amounts of fatty acids cross the sheep placenta. They are derived mainly from the maternal plasma free fatty acids and might just be sufficient to be the source of the small amounts of essential fatty acids found in the lamb fetus, but are insignificant in terms of energy supply or lipid storage.

Adipose Tissue↗
PubMed1978

Cord blood hypertriglyceridaemia as an index of fetal stress: use of a simple screening test and results of further biochemical analysis.

In this preliminary study, 120 cord blood samples were subjected to a simple on-the-ward triglyceride screening procedure and 15 were designated as being high and another 15 randomly selected as controls. All the samples were then subjected to detailed biochemical analysis for fatty acid profiles and/or concentrations of free fatty acids, triglycerides (TG), phospholipids, cholesterol esters and glycerol. Eleven of the samples designated 'high' were associated with one or more of the following clinical conditions: family history of ischaemic heart disease, maternal starvation, fetal distress, light-for-dates babies and excessive weight gain during pregnancy. There was an association between high TG levels and high glycerol levels. The fatty acid pattern of the TG was altered when at abnormally high concentration, in particular oleic acid was increased relative to the others, and this was associated with an increase in cholesterol ester oleic acid. The possible mechanisms resulting in cord hypertriglyceridaemia are discussed.

Cholesterol Esters↗
PubMed1978

The passage of fat emulsion across the human placenta.

Six patients near term were given an intravenous infusion of a fat emulsion (Intralipid) a few hours before normal delivery or Caesarean section. Six other non-infused patients were studied as controls. Maternal venous and umbilical venous and arterial blood samples were taken at delivery and analyzed for individual fatty acid concentrations in triglyceride, free fatty acid (FFA) and phospholipid fractions. The emulsion, being rich in oleic and linoleic acids, affected the composition of the maternal triglycerides. The fetal lipids were also altered and the infusions resulted in large positive umbilical venous-arterial (v-a) differences in FFA and triglyceride fatty acid concentrations, but this was not the case for phospholipid concentrations. The fatty acids with the largest v-a differences were those prominent in the emulsion.

Adult↗
PubMed1978

Source of fetal-stored lipids during maternal starvation in rabbits.

The effect of 48 h maternal starvation on the composition of fetal rabbit brown and white adipose tissue was examined. Compared with fed control rabbits, adipose tissue triglyceride fatty acids took on a composition more like that of maternal plasma free fatty acids (FFA), whose concentration more than doubled after 48 h starvation. It is concluded that maternal FFA contribution to the fetal lipids increases during starvation and certain fetal acids, in particular linoleic acid, may in the fed state be derived from maternal lipids other than the FFA.

Adipose Tissue↗
PubMed1978

Effect of maternal glucose infusions on fatty acid transport across the placenta in rabbits.

Glucose infusions given intravenously to 28-day-pregnant rabbits increased maternal and fetal plasma immunoreactive insulin levels and decreased maternal concentrations of circulating free fatty acid (FFA). Fetal plasma FFA were only slightly depressed and umbilical venous-arterial concentration differences were unchanged both for total FFA and for individual fatty acids in the FFA fraction. The mean umbilical venous concentration was twice that of maternal levels in the infused group, but about the same concentration in untreated rabbits. It is concluded that the infused glucose, or the high insulin levels provoked by it, or both, caused an increased flow of FFA to the fetus, probably from sources other than the maternal plasma FFA.

Animals↗
PubMed1977

Diurnal plasma free fatty acid profiles in normal and diabetic pregnancies.

Diurnal plasma free fatty acid (FFA) and glucose concentrations were measured in 23 normal women, 13 chemical diabetics, and 11 insulin-dependent diabetics in late pregnancy. The mean diurnal FFA value was lowest in the insulin-requiring diabetics and highest in the chemical diabetics. Although no association was found between percentile birthweight and maternal mean fasting or diurnal FFA, there was a positive correlation between percentile birthweight and both mean maternal fasting plasma glucose and mean diurnal glucose in normal and chemical diabetic women. These observations support the view that glucose is the major substrate used by the fetus, but birthweight may be influenced more by the total substrate crossing the placenta than by maternal levels of either glucose or FFA alone.

Adult↗