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Biomedical subjects

J Stammers

Publications and source records attributed to J Stammers.

9 recordsLinked to original sources
PubMed1998

Fatty acid balance studies in preterm infants fed formula milk containing long-chain polyunsaturated fatty acids (LCP) II.

A milk formula (Prematil-LCP) containing long-chain polyunsaturated fatty acids (LCP) and with a fatty acid profile closely resembling breast milk has recently been introduced for preterm infants. A double-blind randomized controlled trial was performed comparing fatty acid absorption from Prematil-LCP (n=10) and standard Prematil (n=10). Formula-fed preterm infants underwent 3 d fat balances (once full enteral feeds were established) along with a parallel human milk fed group (n=11). Plasma samples were taken on the last day. Median total fat excretion (absorption, %) was 2.34g kg(-1) (82.0), 2.64g kg(-1) (82.9) and 1.65g kg(-1) (87.8) with Prematil, Prematil-LCP and human milk feeding, respectively. This reflected differences in the excretion and absorption of long-chain saturated fatty acids. All groups excreted detectable LCP. LCP disappearance was higher in infants fed human milk than in those fed Prematil-LCP, particularly for n-6 LCP (p < 0.01). Nevertheless, excreted LCP equated to < 30% dietary intake, with Prematil-LCP feeding. Plasma lipid fatty acid composition reflected differences in dietary LCP intake.

Analysis of Variance↗
PubMed1998

Fatty acid balance studies in term infants fed formula milk containing long-chain polyunsaturated fatty acids.

Long-chain polyunsaturated fatty acids (LCP) are thought to be required for optimal nervous system development in the newborn. A commercial milk formula containing LCP (Aptamil-LCP) with a fatty acid profile closely resembling breast milk, has recently been introduced for term infants. The absorption of fatty acids in term infants was examined in a double-blind randomized controlled trial comparing Aptamil-LCP (n = 20) and standard Aptamil (n = 20). Formula-fed newborn infants were studied from birth for 14 d. Fat balances (3 d) were performed from d 10. A 3-d stool collection was performed from d 10 in a parallel breastfed group (n = 21). Plasma samples were taken on d 6. Median fat excretion (mg kg[-1]) was 897.1, 615.0 and 355.2 with Aptamil, Aptamil-LCP and breastfeeding, respectively. The median total fat absorption coefficient in Aptamil-LCP-fed infants was higher than in those fed standard Aptamil (p < 0.01). These findings were accounted for by differences in the excretion and absorption of long-chain saturated fatty acids (C14:0, C16:0 and C18:0). Higher fat excretion was associated with bulkier and firmer stools. Only trace amounts of LCP were detected in the stools of all groups. This accounted for less than 4% of dietary intake in Aptamil-LCP-fed infants. No differences in the utilization of LCP from Aptamil-LCP and breast milk feeding were apparent. Plasma phospholipid fatty acid composition data reflected differences in dietary LCP intake. Thus, PL LCP levels were highest in the breastfed infants and lowest in the Aptamil-fed infants, with values for the Aptamil-LCP-fed group falling in between.

Analysis of Variance↗
PubMed1995

Effect on placental transfer of exogenous lipid administered to the pregnant rabbit.

The transfer of lipids across the placenta was measured after infusion of an emulsion of triacylglycerol and phospholipid (intralipid) into 10 anesthetized rabbits. Maternal and umbilical venous and arterial samples were collected at 10-min intervals. All samples were analyzed for concentration and fatty acid composition of FFA, triacylglycerol, and phospholipid fractions. At the end of the infusion period of intralipid, there was a significant increase in the maternal concentrations of total triacylglycerol (p < 0.01) and of total phospholipid (p = 0.01) but not of total FFA (p > 0.05). Maternal plasma triacylglycerol and phospholipid altered in composition to match that of the infused Intralipid by the end of the infusion. Despite the significant rise in maternal triacylglycerol and phospholipid concentrations, the umbilical vein-artery difference for these lipid fractions remained unchanged and very low. In contrast, the umbilical vein-artery difference for FFA (p < 0.02) rose gradually throughout the experiments. There was no significant change in the fatty acid composition of the maternal FFA, but the fatty acid composition of the umbilical vein-artery difference for FFA changed to reflect the composition of Intralipid. These experiments show that exogenous triacylglycerol and phospholipid dramatically alter the lipid fractions presented to the placenta in the maternal plasma but do not cross the placenta intact. However, the composition of the FFA crossing the placenta is modulated to become more similar to that of the exogenous lipid.

Animals↗
PubMed1993

Placental transfer of free fatty acids: importance of fetal albumin concentration and acid-base status.

Free fatty acids (FFA) are the main class of naturally occurring lipids transferred across the placenta, irrespective of species. In order to study the importance of fetal plasma albumin concentration and pH on placental transfer of FFA, in situ perfusion of the rabbit placenta in late gestation was used as an experimental model. Increasing albumin concentration on the fetal side of the placenta from 1 to 6% significantly increased transfer of FFA across the placenta. However, alteration of the umbilical perfusate pH in the range 7.0-7.5 had no significant effect.

Acid-Base Equilibrium↗
PubMed1992

Two different low birth weight formulae compared.

The performance of two different, commercially available, low birth weight formulae feeds was compared in preterm infants. The aim of the study was to determine the effect of compositional differences on tolerance, stool frequency and consistency, fat balance and weight gain. Inborn infants with birth weight less than 1500 g were randomised at birth to receive Prematil or Osterprem. Thirty infants received more than 900 ml/kg per week of designated formula alone during a total of 70 weeks of study. Three day fat balance was performed on 23 infants. Osterprem contains 40% more fat than Prematil. The composition of this fat is different in that Osterprem contains no medium chain triglycerides (MCT) compared to 30% in Prematil. Clinical evaluation demonstrated that Osterprem is associated with a significantly higher mean energy intake compared to Prematil (3442 and 3127 kJ/kg per week) but mean weight gain is not significantly different (123 and 112 g/kg per week). Mean stool frequency is higher on Osterprem (20.5 and 14.5 stool/week) and the consistency of stools firmer. This is attributable to a higher mean fat output (2.3 and 0.9 g/kg per day) secondary to the higher fat content of the feed and lower mean absorption (71.6 and 83.5%). Both feeds are well tolerated. The study also confirms that absorption of unsaturated fatty acids is inversely proportional to chain length.

Dietary Fats↗
PubMed1992

Evaluation of techniques for delivery of steroids to lungs of neonates using a rabbit model.

Little is known about delivery of aerosolised steroids to neonatal patients undergoing assisted positive pressure ventilation and after extubation. A rabbit model has been established to investigate factors influencing drug delivery. Beclomethasone dipropionate, in a metered dose inhaler, was radiolabelled with technetium 99m. The mass median aerodynamic diameter of the aerosol was 3.3 (2.0) microns and the impactor measurements confirmed that the technetium distribution corresponded with that of the drug particles. The metered dose inhaler was actuated into a collapsible spacer that was used to ventilate and deliver aerosol to anaesthetised rabbits by a tracheostomy. From each actuation of the drug 2.9 (0.4)% of the aerosol deposited in the trachea and main bronchi and 1.2 (0.4)% in the lung. When the drug was delivered by a spacer device, with face-mask attachment, to rabbits breathing freely through a tracheostomy, aerosol deposition increased to 4.4 (2.1)% in the trachea and main bronchi and 1.9 (0.9)% in the lung lobes. The maximum change in systolic blood pressure after administration of aerosol by the collapsible spacer was a decrease of 13%. The methods described may prove useful for the delivery of inhaled steroids to neonatal patients likely to develop bronchopulmonary dysplasia.

Administration, Inhalation↗
PubMed1992

New aerosol delivery system for neonatal ventilator circuits.

There is mounting evidence that a variety of drugs delivered as aerosols are likely to be of benefit in neonatal units. To avoid many of the problems associated with the use of jet nebulisers in ventilator circuits, a chamber was designed to be used in conjunction with a metered dose inhaler (MDI). The dimensions (4 cm x 11 cm) were chosen in an attempt to maximise drug delivery. In vitro studies were subsequently performed in order to determine the optimum operating conditions. Sodium cromoglycate delivered via this system was collected on a filter placed between the tip of an endotracheal tube and a model lung. The dose delivered was determined by means of an ultraviolet spectrophotometric assay. Using a Draeger Babylog 8000 ventilator it was found that drug delivery as maximised by actuating the device just before the inspiratory cycle when the chamber was placed adjacent to the endotracheal tube and by using a long (one second) inspiratory time. Under these conditions 1.5-2% of the original dose was deposited upon the filter at tidal volumes of 11-22 ml. When considered in terms of body weight this is many times the equivalent dose delivered to adults from an MDI. Effective drug delivery to the filter was confirmed using a radiolabelled aerosol. Radiolabelled studies delivering aerosol to the lungs of intubated rabbits demonstrated that deposition aerosol was distributed uniformly between lobes when corrected for the weight of each lobe. In conclusion, the device appears likely to deliver significant, reproducible quantities of drug to the lower respiratory tract while being simple to use.

Aerosols↗
PubMed1987

The effects of dietary supplementation with fish oil in patients with psoriasis.

Ten patients with psoriasis resistant to conventional topical treatment were given dietary supplements of fish oil, providing approximately 12 g of eicosapentaenoic acid daily for a period of at least 6 weeks. In eight patients there was a modest improvement in their psoriasis, the principal effects being a diminution of erythema and scaling. The dietary treatment resulted in a substantial inhibition of leukotriene B4 production by the peripheral blood polymorphonuclear leukocytes in vitro. The discrepancy between the high degree of inhibition of leukotriene B4 synthesis and the modest therapeutic effect suggests that leukotriene B4 is not the only mediator involved in the development of the psoriatic lesion. Furthermore, the in vivo cutaneous levels of leukotriene B4 might not have been inhibited to the same extent as the polymorphonuclear leukocyte levels in vitro. Further studies on the use of fish oil supplements, both on their own and in conjunction with other forms of treatment in psoriasis are warranted. It will also be important to determine whether the altered profile of 5-lipoxygenase products found in the blood is also seen in the skin.

Adult↗