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Biomedical subjects

A Lucas

Publications and source records attributed to A Lucas.

At least 361 records · Page 20Linked to original sources
PubMed1980

The nipple-shield sampling system: a device for measuring the dietary intake of breast-fed infants.

We have devised a method for the determination of the composition of the milk infants obtain from the breast during suckling itself, suckled breast milk (SBM). The method involves the use of a nipple-shield sampling system, together with data on the pattern of milk flow from mother to infant derived from a cross-sectional analysis of test weighings during feeding. In this study, marked changes were demonstrated in milk fat the sixth day postpartum. From this information the total intake of fat and energy during the feed was calculated. These preliminary findings suggest that published information on the dietary intake of breast-fed infants may need some revision.

Breast Feeding↗
PubMed1980

Plasma secretin in neonates.

Plasma secretin has been measured in 96 normal 6-day-old term infants and in 158 healthy preterm infants whose mean post-partum ages were 2 1/2, 6, 13 or 24-days. At birth, plasma secretin levels in both term and preterm infants were high compared with those seen in healthy fasting adults (p less than 0.001), but subsequently declined towards adult values. In contrast, preterm infants who had not been fed for the first 6 days of life, had presistently high basal plasma secretin values. In term infants at 6 days of age and in preterm infants up to 13 days, there was no secretin response to a feed. However, by 24 days, preterm infants showed a marked postprandial secretin elevation (p less than 0.02). No correlations were found between plasma secretin concentrations and either blood glucose or plasma insulin concentrations following a feed. Significant adjustments in plasma secretin levels occur in the early weeks of life which may be influenced by enteral feeding.

Adult↗
PubMed1980

Plasma pancreatic polypeptide in the human neonate.

Plasma pancreatic polypeptide (PP) concentrations have been studied in 197 healthy term and preterm infants. At birth plasma concentrations were lower than those found in the young fasting adult (p less than 0.01), but by the sixth postnatal day in both term and preterm infants basal concentrations had risen to adult levels. In preterm infants, who were studied at two further postnatal ages, 13 and 24 days, basal plasma PP concentrations peaked at 13 days with levels that were over twice those seen in fasting adults (p less than 0.005). However, the marked PP elevations following feeding that have been reported in adults, were not seen in any of the groups of neonates studied. PP physiology thus appears to differ in neonates and adults. These findings may be relevant to adaptation to postnatal life.

Adult↗
PubMed1980

Developmental aspects of gastric inhibitory polypeptide (GIP) and its possible role in the enteroinsular axis in neonates.

Little is known on the development of the release of gastric inhibitory polypeptide (GIP) in neonates or on its potential role in the enteroinsular axis. Using cross-section data collection we studied: (a) 100 preterm neonates either at birth (cord blood), or before or after a feed on the sixth or 24th day and (b) 63 term neonates at birth or on the sixth day. Blood samples were assayed for GIP, insulin and glucose. At birth plasma GIP concentrations were low compared with fasting adults (p less than 0.01). Basal plasma levels were significantly higher at six days in fed infants, but not in a group of sick preterm infants who had never been fed orally. On the sixth day there was no GIP response to a feed, but by 24th day there was a marked postprandial elevation (p less than 0.01). In preterm infants the insulin response was 68% greater at 24 days than at six days in spite of a similar glycaemic response. We hypothesize that this increasing postnatal insulin response to enteral feeding may be due to the commencement of the postprandial release of GIP, thought to be an important effector in the enteroinsular axis.

Blood Glucose↗
PubMed1980

Prostaglandins in human milk.

Prostaglandins E and F have been shown to be present in breast milk in over 100 times the concentrations found in adult plasma. The ratio of the concentration of the principal circulating metabolite of prostaglandin F (13, 14-dihydro-15-ketoprostaglandin F) to prostaglandin F itself is low (0.3 to 0.5, compared with 15.8 in adult plasma), implying that prostaglandins may have a relatively long half-life in milk. In addition inactive metabolites of thromboxane A2 and prostacyclin are also found in significant amounts. It is speculated that milk prostaglandin play a role in modulating neonatal physiology--for example, gut motility.

Female↗
PubMed1980

Plasma motilin, gastrin, and enteroglucagon and feeding in the human newborn.

Plasma concentrations of motilin, gastrin, and enteroglucagon were measured in cord blood and during the first 24 days of life before feeding in 45 term and 63 preterm, healthy infants. Levels of these hormones rose steeply after birth, reaching concentrations that were much higher than those in fasting adults. These increases in hormone concentration were not present in a group of 10 preterm infants who had received only intravaenous dextrose from birth because of hyaline membrane disease. Our findings suggest that early enteral feeding may trigger the postnatal increase in plasma concentrations of gut hormones and that this could play an important role in the physiologaical adaptations to extrauterine nutrition.

Fetal Blood↗
PubMed1980

Development of gut hormone responses to feeding in neonates.

The development of the effects of a human milk feed on plasma concentrations of motilin, neurotensin, gastric inhibitory polypeptide, enteroglucagon, gastrin, and secretin were studied in 158 healthy preterm neonates (mean gestation 33 1/2 weeks) at mean postnatal ages of 2 1/2, 6, 13, or 24 days. Pronounced progressive changes occurred in postprandial hormone responses; these were absent or small in the first days of life and were large by age 24 days. These changes may have important consequences in the adaptation to postnatal life.

Age Factors↗
PubMed1979

Pattern of milk flow in breast-fed infants.

122 six-day-old infants were test-weighed during breast feeding. Cross-sectional data collection avoided repeated interruptions of individual feeds. Milk flow conformed to a definite pattern: a mean of 50% of the feed from each breast was taken in the first two minutes of sucking and a mean of 80-90% was taken by four minutes. The second half of a ten-minute feed from either breast was almost non-nutritive. Preliminary studies suggest that the pattern is the same after one month of lactation.

Breast Feeding↗
PubMed1979

Bacteriological quality control in human milk-banking.

The bacteriological quality of pooled human milk donated to the Oxford milk bank was analysed and the effects on bacteriology of sterilisation of the milk-collecting vessels in the home with hypochlorite solution and of Holder pasteurisation in a purpose-built human-milk pasteuriser were studied. Collecting milk in hypochlorite-sterilised vessels resulted in a significantly lower bacterial count of both pathogens and species of unlikely pathogenicity before pasteurisation and significantly increased the chance of pasteurisation giving a sterile product. Potentially pathogenic organisms grown in untreated milk were Escherichia coli, Staphylococcus aureus, and group B beta-haemolytic streptococci. Seven species of organisms of unlikely pathogenicity were also identified. Pasteurisation eliminated all potential pathogens from milk but did not reliably remove any of the species of unlikely pathogens. Banked human milk may be contaminated with bacteria which are known to be capable of producing lipases, proteases, and decarboxylases. Accurate pasteurisation, together with attention to the sterility of the collecting vessels, results in a bacteriologically safe product that retains many of the protective properties of raw milk.

Disinfection↗
PubMed1979

The effect of feeds of differing composition on entero-insular hormone secretion in the first hours of life in human neonates.

Little is known on the enteral stimuli for gastro-intestinal hormone release in newborn infants. We have compared the effect of the first feed of human breast milk (5 ml/kg) or 10% dextrose (5 ml/kg) on blood glucose and plasma gastrin, enteroglucagon, Gastric Inhibitory polypeptide (GIP), pancreatic glucagon, and insulin in 21 full-term infants at 4--6 hours of age. The first feed of human milk caused a rise in blood glucose and plasma insulin, gastrin and enteroglucagon, but no change occurred in GIP or pancreatic glucagon. The 10% dextrose feed did not stimulate enteroglucagon release, although similar changes occurred in blood glucose and plasma insulin and gastrin. We conclude that the composition of the feed influences the pattern of gastro-intestinal hormone release during the first hours of life and that the entero-insular responses to feeding differ in the neonate and the adult.

Blood Glucose↗
PubMed1979

Catecholamines in dogs during cold adaptation by repeated immersions.

Dogs were immersed in cold water 1 h/day for 30 consecutive days. During the first immersion, oxygen uptake increased approximately sevenfold and colonic temperature decreased; a large increase in plasma epinephrine and norepinephrine concentrations was found; plasma glucose, lactic acid, and free fatty acid (FFA) concentrations were also increased. An adaptative response to cold was evidenced during the 10th immersion by a further increase in oxygen uptake and a reduction in the fall of colonic temperature; plasma epinephrine, glucose, and lactic acid were diminished whereas FFA were higher. Consequently 10 h spent in cold are sufficient to induce an improved capacity for heat production. An enhanced ability to produce nonshivering thermogenesis mediated by epinephrine or norepinephrine is not obvious because after the 30th immersion no enhanced calorigenic response to epinephrine or norepinephrine infusion was found. In dogs mechanisms other than norepinephrine-enhanced sensitivity might be involved in this kind of cold adaptation.

Adaptation, Physiological↗
PubMed1979

Calorigenic effect of insulin in hypothermic dogs.

In dogs acutely immersed in cold water (8--13 degrees C), oxygen uptake increased approximately sevenfold and colonic temperature rapidly began to decrease. Fifteen minutes after the start of immersion a high level of hyperglycemia was found but no increase in immunoreactive plasma insulin level was observed. Under these conditions exogenous insulin (0.3 U.kg-1) induced a further increase in oxygen uptake and in shivering intensity whereas a decrease in the fall of colonic temperature was observed. It can be concluded that insulin may have a calorigenic effect and improve the resistance to cold of dogs exposed to an acute cold stress.

Animals↗
PubMed1979

A Doppler ultrasound technique for measuring human milk flow.

The authors describe the development of a Doppler ultrasound flow transducer used in conjunction with a zero-crossing demodulator for breast milk flow measurement. The results of the preliminary evaluation in vitro are presented in the paper. The design is at present being minaturised in order to use the transducer for in vivo measurement.

Breast Feeding↗