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Biomedical subjects

A Lucas

Publications and source records attributed to A Lucas.

At least 271 records · Page 15Linked to original sources
PubMed1988

Increased energy expenditure in young children with cystic fibrosis.

To investigate the role of energy expenditure in the altered energy balance in cystic fibrosis (CF), total energy expenditure (TEE) was measured by the doubly-labelled water method in 9 clinically well CF infants (body weight 7.3-10.9 kg) without chronic lung disease. CF infants had 25% higher rates of energy expenditure when compared with data derived from measurements of TEE obtained by the same method in 16 healthy infants, matched for age and body weight. Mean TEE (SEM) for CF was 950 (38) kcal, vs 876 (72) kcal for controls matched for age and 758 (46) kcal for controls matched for weight. Although subclinical disease activity cannot be excluded as a determinant of the excess TEE, the possibility of an energy-requiring basic defect is suggested, because further analysis indicated that factors other than body weight, degree of underweight, presence of pancreatic insufficiency, or presence of lung disease were important. Increased TEE may contribute to undernutrition in CF, even in the absence of chronic lung disease.

Body Water↗
PubMed1988

Maternal fatness and viability of preterm infants.

To investigate the effect of maternal fatness on the mortality of infants born preterm up to the corrected age of 18 months 795 mother-infant pairs were studied. Maternal fatness was defined by Quetelet's index (weight/(height] and all infants weighed less than 1850 g at birth. In 771 mother-infant pairs maternal age, complications of pregnancy, mode of delivery, parity, social class, and the baby's sex and gestation were analysed by a logistic regression model for associations with infant mortality (but deaths from severe congenital abnormalities and those occurring during the first 48 hours after birth were excluded). In a subgroup of 284 mother-infant pairs all infant deaths except those from severe congenital abnormalities were analysed in association with the infant's birth weight and gestation and the mother's height and weight; this second analysis included another 24 infants who had died within 48 hours after birth. In the first analysis mortality overall was 7% (55/771), rising from 4% (71/173) in thin mothers (Quetelet's index less than 20) to 15% (6/40) in mothers with grades II and III obesity (Quetelet's index greater than 30). After adjusting for major demographic and antenatal factors, including serious complications of pregnancy, maternal fatness was second in importance only to length of gestation in predicting death of infants born preterm. In the second analysis mortality overall was 15% (44/284), rising from 9% (5/53) in thin mothers to 47% (8/17) in mothers with grades II and III obesity. In both analyses the relative risk of death by 18 months post-term was nearly four times greater in infants born to obese mothers than in those born to thin mothers. In addition, maternal fatness was associated with reduced birth weight, whereas it is associated with macrosomia in term infants. These data differ fundamentally from those reported in full term babies of obese mothers. It is speculated that the altered metabolic milieu in obesity may reduce the ability of the fetus to adapt to extrauterine life if it is born preterm.

Adult↗
PubMed1988

Energy expenditure and intake in infants born to lean and overweight mothers.

We investigated the contributions of low energy expenditure and high energy intake to excessive weight gain in infants born to overweight mothers. The subjects were infants of 6 lean and 12 overweight mothers, recruited soon after birth. Total energy expenditure and metabolizable energy intake were measured with a new doubly labeled water method over a period of seven days when the infants were 3 months of age, and the postprandial metabolic rate was measured by indirect calorimetry when the infants were 0.1 and 3 months of age. The results were related to weight gain in the first year of life. No significant difference was observed between infants who became overweight by the age of one year (50 percent of infants born to overweight mothers) and those who did not, with respect to weight, length, skinfold thicknesses, metabolic rate at 0.1 and 3 months of age, and metabolizable energy intake at 3 months. However, total energy expenditure at three months of age was 20.7 percent lower in the infants who became overweight than in the other infants (means +/- SE, 256 +/- 27 and 323 +/- 12 kJ per kilogram of body weight per day; P less than 0.05). This difference could account for the mean difference in weight gain. These data suggest that reduced energy expenditure, particularly on physical activity, was an important factor in the rapid weight gain during the first year of life in infants born to overweight mothers.

Body Weight↗
PubMed1988

Factors associated with maternal choice to provide breast milk for low birthweight infants.

Factors associated with maternal choice to provide milk for premature infants were investigated in 925 mother/infant pairs in five hospitals. A well educated, married, primiparous mother aged 20 or over who delivered a baby boy by caesarean section was nearly 1000 times more likely to choose to express her milk than a mother who was poorly educated, single, multiparous, and aged under 20, delivering a female infant vaginally. Evidence from the five centres suggested that hospital staff have little influence on a mother's choice of feeding method. The major differences between the populations of babies whose mothers do or do not choose to provide milk, raise important issues concerning the interpretation of data from non-randomised clinical trials of feeding premature infants.

Birth Order↗
PubMed1988

Plasma testosterone in preterm infants with cryptorchidism.

Cryptorchidism is common in infants born preterm, yet the mechanism for its occurrence is still debated. In a study of 21 premature babies with cryptorchidism at 18 months post-term and 21 case matched controls, cryptorchid preterm infants failed to show the normal rise in plasma testosterone in the first postnatal week. This rise is thought to relate to residual maternal human chorionic gonadotrophin in the neonatal circulation. Infants with cryptorchidism also failed to show the later testosterone surge in the second month which has been related to endogenous gonadotrophin release. We speculate that inadequate stimulation of testosterone release by human chorionic gonadotrophin in the fetus might contribute to the pathogenesis of cryptorchidism in preterm infants. Our findings have implications for the medical treatment or possible prophylaxis of undescended testes in premature babies.

Age Factors↗
PubMed1988

Low plasma triiodothyronine concentrations and outcome in preterm infants.

A major association has been found between low plasma triiodothyronine concentrations in preterm neonates and their later developmental outcome. Plasma triiodothyronine concentration was measured longitudinally in 280 preterm infants below 1850 g birth weight. Babies whose lowest recorded concentration was less than 0.3 nmol/l had, at 18 months' corrected age, 8.3 and 7.4 point disadvantages in Bayley mental and motor scales and a 8.6 point disadvantage on the academic scale of Developmental Profile II, even after adjusting for a range of antenatal and neonatal factors known to influence later development. Low concentrations of triiodothyronine were strongly associated with infant mortality, but not after adjusting for the presence of respiratory illness. There was no association between plasma triiodothyronine concentrations and somatic growth up to 18 months, and no association with necrotising enterocolitis or later cerebral palsy. Data on postnatal changes in plasma triiodothyronine concentrations are presented for reference purposes. While cited reference ranges for plasma triiodothyronine concentration appear suitable for well infants above 1500 g birth weight, smaller or ill babies often have very low values for many weeks. Our data are relevant to the debate on endocrine 'replacement' treatment in premature babies.

Age Factors↗
PubMed1988

Mother's choice to provide breast milk and developmental outcome.

The association between a mother's choice to provide breast milk and her baby's developmental status at 18 months post term was investigated in 771 low birthweight infants from five centres. Babies whose mothers chose to provide milk had an 8 point advantage in mean Bayley mental developmental index over infants of mothers choosing not to do so. A 4.3 point advantage remained after adjusting for demographic and perinatal factors. A similar finding was derived using a fundamentally different and questionnaire based test (academic scale of Developmental Profile II). Whether this significant residual developmental advantage relates to parental factors or to a beneficial effect of human milk itself on brain development has important implications for the nutritional management of premature babies.

Breast Feeding↗
PubMed1988

Early sodium intake and later blood pressure in preterm infants.

The relation between early salt intake and later hypertension is debated. As part of a larger feeding study, 347 preterm infants were randomly assigned to receive early diets differing grossly in sodium content. Feeding a high sodium preterm formula in the neonatal period did not influence arterial blood pressure at 18 months (corrected) age.

Blood Pressure↗
PubMed1988

Effect of weaning on accuracy of doubly labeled water method in infants.

Variations in background 2H and 18O abundances in body water influence the accuracy and precision of the 2H218O method for determination of energy expenditure. To investigate the effect of weaning during infancy on background 2H and 18O abundances, urine samples from 44 breast- or formula-fed infants aged 5-16 wk were analyzed. 2H and 18O abundances were significantly higher (P less than 0.001) in breast- than in formula-fed infants. The relationship between 2H and 18O abundances was linear and independent of diet [slope, 4.16 +/- 0.43 (SE)]. By use of this information, the effect of weaning on the accuracy of the 2H218O method was evaluated, taking into account the effect of 2H-18O abundances in the isotope loading dose. In infants weaned completely from breast milk to formula during the measurement, energy expenditure can be overestimated by 18.0%, even if 2H-18O abundances in the isotope dose equal the ratio of naturally occurring background changes. However, this error can be reduced to less than 3.0% by manipulating the study duration and isotope dose. During gradual weaning, the overestimation of energy expenditure is only 0.3-2.0%.

Aging↗
PubMed1987

How much energy does the breast fed infant consume and expend?

Energy intake in breast fed infants is uncertain. The doubly labelled water method was used to measure, simultaneously and non-invasively, energy expenditure, energy intake, milk volume intake, energy deposition, and the energy content of breast milk in 12 "free living" breast fed babies at 5 and 11 weeks of age. The validity of this new approach was assessed in a parallel study in 12 formula fed infants. The babies who were exclusively breast fed expended 1.28 and 1.68 MJ/day at five and 11 weeks and had intakes of 1.81 and 2.22 MJ/day; these intakes were associated with normal growth but were well below those recommended previously. At five and 11 weeks the calculated energy content of breast milk was 0.24 and 0.25 MJ/100 ml, which is substantially lower than that commonly reported in milk obtained unphysiologically by expression of the breast. These data cast doubt on the widely used published standards for infant feeding.

Breast Feeding↗
PubMed1987

A comparison of structure-activity relationships within alpha-MSH on melanophores of Anolis carolinensis and Rana pipiens.

We have compared the structure-function relationship of the tridecapeptide alpha-melanocyte stimulating hormone (alpha-MSH) on the melanophores of the lizard Anolis carolinensis and the frog Rana pipiens by determining the melanosome-dispersing potency of 15 shorter peptide sequences and 8 substituted alpha-MSH analogues. Major differences were found between the lizard and the frog in their response to alpha-MSH peptide fragments and analogues. In Anolis, the sequence Ser-Tyr-Ser- is not as important for the pigmentary response as in Rana since alpha-MSH-(4-13) was nearly as potent (89%) as alpha-MSH-(1-13) (100%), whereas in Rana alpha-MSH-(4-13) potency was reduced to 7.5%. In addition, loss of potency due to removal of residues Pro and Val was more marked in Rana (alpha-MSH-(1-11) = 0.1%) than in Anolis (alpha-MSH-(1-11) = 1%), suggesting that this C-terminal sequence is necessary for pigmentary activity in the frog melanophore. These results together with those of other peptide fragments and analogues have led us to define the minimal pigmentary sequence of alpha-MSH as alpha-MSH-(4-12) in Anolis in contrast to alpha-MSH-(1-13) in Rana. This suggests that Anolis and Rana alpha-MSH receptors recognise different message amino acids of the alpha-MSH peptide sequence even though the final response (melanosome dispersion) is the same.

Amino Acid Sequence↗