Does lambswool promote growth in preterm infants?
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Animals↗
Biomedical subjects
S B Roberts
Publications and source records attributed to S B Roberts.
Comparison of the doubly labeled water (2H2(18)O) method with indirect calorimetry and a nutrient-balance study for simultaneous determination of energy expenditure, water intake, and metabolizable energy intake in preterm infants.
The doubly labeled water method was compared with indirect calorimetry and a nutrient-balance study for simultaneous determination of rates of CO2 production, energy expenditure, and water intake over 5 days in four preterm infants. Additionally, metabolizable energy (ME) intake estimated using the isotope procedure (as energy expenditure plus an estimate for energy deposition based on weight gain), was compared to ME intake measured in the balance study. Compared to values obtained by traditional methods, calculated CO2 production, energy expenditure, and water intake differed by -1.4 +/- 4.8% (SD), +0.3 +/- 2.6%, and +5.7 +/- 1.4%, respectively; the difference in water intake was significant (p less than 0.05). Calculated ME intakes were 5.3 +/- 19.3% less than measured intakes, but the difference was not significant. These findings indicate that the doubly labeled water method can provide accurate information on rates of CO2 production, energy expenditure, and water intake in preterm infants, but individual estimates of ME intake may be subject to substantial error.
Calorimetry, Indirect↗
The effects of two extremes of dietary intake on protein accretion in preterm infants.
A comparison has been made of protein accretion and growth in premature infants fed banked drip breast milk (BBM) or a preterm formula (PF). Protein accretion was calculated from the difference between dietary nitrogen intake and output in urine and stools, measured in a nutrient balance study. As expected, only the infants fed PF achieved the intrauterine growth rate. However, whilst weight gain in infants fed BBM was 71% of that in the group fed PF, the rate of protein deposition was less than 50%. As a result, the protein concentration in new tissue of infants fed BBM averaged 32% less than in those fed PF and 21% less than the lower end of the range reported to occur in utero. We speculate that infants fed BBM have an abnormally low protein concentration in their lean body mass.
Growth↗
Dietary supplementation increases milk output in the rat.
The effects of dietary supplementation on milk output and maternal body composition were investigated in the lactating rat. The supplement was a cooked homogeneous mixture of eggs and maize oil, and had the same protein-energy: total energy value as the control diet. During 2-12 d post partum rats were fed ad lib., either on the control diet alone or on the control diet plus the supplement. Measurements were made of milk output using an isotope-dilution technique, milk composition, and dam and litter body-composition changes. Compared with the dams receiving only the control diet, dams provided with the supplement consumed 19.7% more energy and protein and produced 31.2% more milk and mobilized less body fat. By 12 d of age, pups in litters of dams receiving the supplement were significantly heavier than those in litters of dams receiving the control diet only, and they contained more protein and more fat. It is concluded that dietary supplementation of lactating rats can enhance lactational performance.
Animals↗
Lactational performance in relation to energy intake in the baboon.
The relationship between energy intake and lactational performance in the baboon was investigated by determining energy intake, milk output and energy balance in animals fed ad libitum during a nonreproductive phase and during lactation, or fed 80% or 60% of ad libitum intake during lactation. No evidence was found for an increased efficiency of energy utilization during lactation when feeding was ad libitum, as judged by calculated energy used on activity and maintenance. Restricted feeding did however produce an increase in efficiency, estimated at 17-25%. This change enabled milk output and body nutrient stores to be protected when the restriction was to 80% of the ad libitum intake but at 60% of ad libitum intake, milk output was reduced and body nutrient mobilization was increased. It is proposed that low maternal food intake is associated with impairment of lactational performance when it is also severe enough to increase body nutrient mobilization.
Animals↗
Effect of ambient temperature on the energy requirements of the lactating rat.
The effect of ambient temperature on the energy requirements of the lactating rat was investigated. Ambient temperature was maintained at 13, 20 or 25 degrees C during lactation, and digestible energy (DE) intake, milk output and energy balance were measured between 4 and 12 d post partum. Ambient temperature did not significantly affect DE intake. Milk output was highest in the rats housed at 13 degrees C and lowest in those kept at 25 degrees C, although the rate of body fat mobilization was lowest in the rats kept at 20 degrees C and highest in the rats kept at 25 degrees C. Energy expenditure on activity and maintenance, determined from the difference between DE intake and body nutrient mobilization plus the energy used for milk production, was significantly higher in the rats housed at 25 degrees C than in those kept at 13 degrees C. This is an opposite trend to that which occurs in nonlactating rats. The results indicate that the gross efficiency of energy utilization during lactation is higher at 13 degrees C than it is at 25 degrees C in the rat.
Adipose Tissue↗
Measurement of urinary constituents and output using disposable napkins.
A procedure for estimating 24 hour urine output in infants using disposable nappies has been validated. In addition, it has been shown experimentally that the urinary concentrations, and hence 24 hour outputs of a range of constituents (sodium, potassium, nitrogen, creatinine, urea, amino acids, and deuterium oxide), may be measured accurately using samples of urine obtained from nappies. It is concluded that the urine collection procedure described has several major advantages over traditional urine bag methods, and has a wide application in clinical practice and research.
Humans↗
The effects of lactation on the relationship between metabolic rate and ambient temperature in the rat.
The oxygen consumption rates of virgin and lactating rats fed ad libitum were measured at temperatures ranging from 1 to 28 degrees C. The oxygen consumption rates of the virgin animals decreased progressively with increasing ambient temperature, but those of the lactating animals decreased slightly between 1 and 8 degrees C, remained approximately constant between 8 and 20 degrees C and fell rapidly above 20 degrees C. It is suggested that the fall in oxygen consumption rate above 20 degrees C in the lactating rats was due to a reduction in milk synthesis rate, and that the thermoneutral zone for normal lactation was 8-20 degrees C; this is a substantially cooler range than that of virgin rats (28-29 degrees C). The net energetic efficiency of milk production was calculated from the energy output in milk and the amount of energy used to produce milk (estimated from the oxygen consumption rates). The value obtained was 57.0%.
Animals↗
Sequence comparisons of non-allelic late histone genes and their early stage counterparts. Evidence for gene conversion within the sea urchin late stage gene family.
We have determined the nucleotide sequence of sea urchin (Lytechinus pictus) late stage H3 and H4 histone genes contained on the clone pLpH3H4 -21 and of the early stage H3 gene contained on the plasmid pLpA . Comparison of these differentially regulated histone genes with each other and with other L. pictus late and early stage histone H3 and H4 genes previously sequenced confirms that members of each histone gene family (early and late) are more homologous to each other than they are to members of other histone gene families. The spacer regions between two late H3-H4 gene pairs on the clones pLpH3H4 -19 and pLpH3H4 -21 have diverged to the point where they are no longer homologous. However, comparative analysis of the 5' flanking DNA has identified a sequence 5'C-T-C-A-T-G-T-A-T-T3' upstream of both late H4 genes and another, 5'A-G-A-T-T-C-A3', upstream of both H3 genes. Except for a short conserved sequence near the initiation codon, the transcribed 5' leaders of the late mRNAs differ in length and sequence in the two non-allelic late histone gene pairs. This divergence contrasts with the 95 to 96% conservation found between late histone gene coding sequences. The results suggest that there is intergenic exchange in the germline among members of the late histone gene family and that the unit of exchange is the individual gene rather than the heterotypic dimer which includes the common spacer DNA.
Animals↗
Lactation increases the efficiency of energy utilization in rats.
The possibility that lactation increases the efficiency of energy use was investigated by comparing energy expenditure on activity and maintenance in virgin and lactating rats fed either ad libitum or restricted amounts of food. Energy expenditure was determined, by difference, in a nutrient balance study. Lactating rats fed ad libitum expended 34.9% less energy on activity and maintenance than did control animals. Of this change, 82% was specifically associated with lactation, but the remaining 18% was associated with the negative energy balance that occurred during lactation. Lactating rats fed restricted amounts of food expended less energy on activity and maintenance than did virgin rats fed at the same level of restriction, but this change was associated with increased negative energy balance and not specifically with lactation. These results indicate that the efficiency of energy use is increased substantially during lactation in the rat, regardless of the level of energy intake, and that mechanisms associated with negative energy balance play an important role in the change.
Adipose Tissue↗
Dietary supplementation of lactating Gambian women. I. Effect on breast-milk volume and quality.
In order to test whether lactational capacity can be improved by dietary interventions, a nutritionally balanced supplement was provided under carefully controlled conditions to 130 nursing mothers in Keneba, The Gambia over 12 months. Maternal mean energy intake (+/- s.e.) increased from 1568 +/- 15 kcal/d (6.56 +/- 0.06 MJ/d) to 2291 +/- 14 kcal/d (9.59 +/- 0.06 MJ/d). Protein intake was in excess of the WHO/FAO recommended intake after supplementation and serious deficits of riboflavin, vitamin A, vitamin C and calcium were rectified. The supplement had no effect on breast-milk volume, compared with retrospective controls, at any stage of lactation or in any season of the year. There was no selective effect on women with poor milk outputs. The average milk protein concentration was slightly improved over the entire period of lactation (+ 6.6 per cent, P less than 0.01), but the total energy content was unchanged since an increase in breast-milk fat concentration (+ 7.9 per cent, n.s.) was offset by a decrease in the milk lactose concentration (- 7.6 per cent, P less than 0.01). Breast milk vitamin content was improved for those vitamins for which the supplement provided a significant proportion of the recommended dietary intake.
Adult↗
Water turnover and the measurement of milk intake.
Physiologically acceptable methods for estimating milk intake in experimental animals area based on the measurement of rates of disappearance of 3H2O from their body-water. This work discusses the problems involved in using methods of this type when steady-states (constant trace inflow and outflow rates, and constant pool-size) do not exist. Theoretically sound techniques are developed and their use justified.
Animals↗
Collum intertextum--a case report of a campanological crisis.
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Burns↗
Seasonal changes in activity, birth weight and lactational performance in rural Gambian women.
The activity of 81 pregnant, lactating and non-pregnant, non-lactating women in the rural subsistence farming village of Keneba, The Gambia, was measured for 12 months using a combination of 24-hour activity recall and activity diaries. During the course of pregnancy women became gradually less active and in the month before giving birth were 25% less active than non-pregnant, non-lactating women and lactating women when women in the month after birth were excluded. There were striking seasonal changes in activity. During the dry season, from January to April, lactating women were active 55% of the 15-hour working day. At the start of the farming season in June and July this figure increased to 92%. Similar changes were observed in the pregnant women whose activity increased from a mean 50% in April to 83% in June. The period of intense activity coincided with a general shortage of food and increased incidence of disease. The intense activity of pregnant women in the farming season coupled with the low food intakes are most probably the main factors responsible for the striking fall in birth weights observed at this time of the year. Reduced lactational performance was apparent in relation to high activity when it necessitated the mother regularly spending much of the day away from her child. FAO/WHO-recommended energy intakes during pregnancy and lactation are inappropriate for this community.
Activities of Daily Living↗
Intraoperative renal calculus imaging.
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Humans↗
Long-term energy balance in child-bearing Gambian women.
The energy intake of 143 pregnant and lactating Gambian women was measured prospectively each week for a year. Anthropometric, birth weight, and breast milk output measurements were also obtained. The average energy intakes (+/- SE) during the dry and wet seasons respectively were: pregnancy, 1483 +/- 22 and 1417 +/- 41 kcal/day; lactation (1st trimester), 1773 +/- 31 and 1474 +/- 42 kcal/day; lactation (subsequent trimesters), 1662 +/- 16 and 1413 +/- 37 kcal/day. Pregnant women gained 1.4 kg body weight per month in the dry season, but only 0.4 kg in the wet season. Lactating women gained weight in the dry season and lost weight in the wet season. Maternal nutritional status did not deteriorate with increasing parity. Mean birth weights (+/- SE) were: 2.94 +/- 0.07 and 2.78 +/- 0.11 kg in dry and wet seasons, respectively. Breast milk output and quality and early infant growth were close to values from well-nourished communities during the dry season, but deteriorated markedly during the wet season. Wet season energy intakes were clearly inadequate, but these results indicate that, despite being low by international standards, the dry season intake was compatible with a good lactational performance. Except for a somewhat low birth weight, which is partly explained by small maternal stature, progress during pregnancy was also remarkably normal during the dry season.
Birth Weight↗
Dietary supplementation of Gambian nursing mothers and lactational performance.
A dietary supplement, resulting in a mean net increase in energy intake of over 700 kcal/day, was supplied to all nursing mothers in a West African village for 12 months. The supplement produced a slight initial improvement in maternal body weight and subcutaneous fat stores but did not increase breast-milk output or fat content.
Body Weight↗
The effect of serum and multiplication stimulating activity on L6 myoblast growth: the lack of correlation with cyclic nucleotide changes.
The role of cAMP and cGMP in triggering proliferation of rat myoblasts was evaluated by: (1) measuring effects of mitogens on intracellular cyclic nucleotide levels, and (2) observing effects of agents which altered cyclic nucleotide levels on cell proliferation. Multiplication stimulating activity (MSA, 1 microgram/ml), a member of the somatomedin family, stimulated cell proliferation after 48 hr. It had little effect on cellular cyclic nucleotide levels, measured by radioimmunoassay. Horse serum (HS) and fetal bovine serum (FBS) stimulated cell proliferation approximately equally. Neither affected cAMP levels; FBS reduced cGMP to 33% of control values, but HS had no effect. Thus, there was no simple correlation between mitogenic action and cyclic nucleotide levels at any time from 5 min to 24 hr after addition of a purified mitogen or serum. Furthermore, agents which caused substantial changes in cyclic nucleotide levels had no effect on cell proliferation. Prostaglandin E1 (5 microM) elevated cAMP 440% without affecting cGMP levels or cell growth. A potent phosphodiesterase inhibitor, 1-methyl-3-isobutylxanthine (MIX, 0.1 mM), when added alone or in the presence of MSA, HS, or FBS, elevated cAMP 200% and cGMP 167%, but it had little effect on their mitogenic action. Lastly, a purified mitogen such as MSA, unlike serum, must be present for extended periods of time in order to stimulate cell proliferation. This makes it unlikely that a trigger mechanism functions in initiating cell division. We conclude that neither cAMP nor cGMP appear to be second messengers for the mitogenic action of MSA or serum on muscle cells.
Animals↗