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Biomedical subjects

T Stephenson

Publications and source records attributed to T Stephenson.

At least 73 records · Page 4Linked to original sources
PubMed2001

Sensitive LH and FSH assays for monitoring low serum levels in men undergoing steroidal contraception.

BACKGROUND AND OBJECTIVES: Current immunoassays for detecting serum FSH and LH are not sufficiently sensitive to detect the markedly reduced levels in men undergoing steroidal hormonal treatment for contraceptive purposes. The purpose of this study was to increase the sensitivity of available LH and FSH immunofluorometric (Delfia) assays in order to allow a better understanding of the importance of gonadotrophin suppression in achieving the optimal suppression of sperm count. DESIGN AND PATIENTS: Assay conditions were modified by increasing serum sample volume, the inclusion of either FSH- or LH-depleted serum to reduce the resulting matrix effects and extending incubation times. The microassays were applied to serum from 10 men administered testosterone enanthate with or without depot medroxyprogesterone acetate for 12 weeks as part of a contraceptive trial. RESULTS: The assay sensitivities were increased to 0.005 IU/l for LH and 0.010 IU/l for FSH, representing a five- to six-fold increase in sensitivity compared with existing assays. In the clinical trial, serum LH levels were suppressed to near or below the level of assay detection (mean 0.014 IU/l < 0.4% of pretreatment values) while in eight of 10 men, plasma FSH levels were detectable (0.04-0.07 IU/l, 1-5% of pretreatment values). These FSH levels would not have been detected by current assays. CONCLUSIONS: The increased sensitivities of the LH and FSH assays enabled the detection of gonadotrophins that were < 0.4% of pretreatment serum levels. Using these methods, serum LH was suppressed to nondetectable or near nondetectable levels while serum FSH was highly suppressed but still detectable in the majority of men undergoing steroidal treatment for contraceptive purposes.

Contraceptive Agents, Male↗
PubMed2001

Accounting for overlap? An application of Mezzich's kappa statistic to test interrater reliability of interview data on parental accident and emergency attendance.

STUDY RATIONALE: The number of interview studies with service users is rising because of growth in health services research. The level of agreement between multiple interview data coders requires statistical calculation to support results. Basic kappa statistics are often used but this depends on having mutually exclusive data. Researchers should be aware that this is not valid when an interview word or paragraph can be coded into more than one category. The 'proportional overlap' kappa extension by Mezzich et al. (1981, Journal of Psychiatric Research 16, 29-39) has been investigated as an original solution. OBJECTIVES: To assess the level of agreement beyond chance between several raters of interview data by applying the 'proportional overlap' kappa statistic by Mezzich et al. to verbal interview data. The clinical area investigated was child attendance at an Accident and Emergency Department, where parental attendance experiences have been under-explored. METHODS: Two researchers using a coding schedule coded a random sample of interview transcripts. These data were applied to Mezzich's procedure; coder 1 notes that a paragraph refers to category A and B but coder 2 notes A, B and C. The total agreement overlap in this case was 0.66 because two actual agreements out of three possible agreements were made. This was repeated for each paragraph and divided by the number of coding pairs. All agreement values were summed then subsequently divided by the total number of paragraphs to get Po (total number of observed agreements) and by the total number of coding pairs to get Pe (total number of agreements by chance alone). Po and Pe were used in the basic kappa formula to assess interview coding reliability. RESULTS: The overall mean Po was 0.61, the mean Pe was 0.32, with a kappa score of 0.43; a moderate level of agreement which was statistically significant (t=4.8, P < 0.001, d.f.=23). CONCLUSION: Mezzich's procedure may be applied to interview data to calculate agreement levels between several coders.

Accidents↗
PubMed2001

The role of leptin in the transition from fetus to neonate.

Leptin is a 16 kDa hormone which has been shown to have a major physiological role in the control of energy balance. Leptin is produced primarily in white adipose tissue, although there is evidence for its production in brown adipose tissue (BAT) and the placenta. BAT is critically important for the initiation of non-shivering thermogenesis in the newborn through the BAT-specific uncoupling protein (UCP), UCPI. This factor is particularly important in lambs in which levels of UCP1 peak at birth, concomitant with a rapid decline in plasma leptin levels. Our studies have examined the effect of acute and chronic administration of leptin to neonatal lambs, investigating effects on colonic temperature, UCP1 and thermogenic potential of BAT. Administration of leptin in sequential physiological doses of 10, 100 and 100 microg to neonatal lambs caused a modest increase in colonic temperature which was not observed in weight-matched vehicle-treated controls. This increase in colonic temperature was not mediated by an increase in either abundance or thermogenic potential of UCPI, as previously shown in adult rodents. UCP1 mRNA levels were 30 % lower in leptin-treated lambs, which is also contradictory to findings in adult rodents. Leptin treatment resulted in a dose-dependent rise in plasma leptin, with levels at the end of the study being almost twenty times greater in leptin-treated animals. To determine whether these findings in neonatal lambs were transient due to the complex milieu of hormones present after birth, we examined the effect of chronic leptin treatment over 6 d. Pairs of lambs were treated daily, from the second to seventh day of life with 100 microg leptin or vehicle. Colonic temperatures of leptin- and vehicle-treated animals remained similar throughout the study. UCP1 abundance was significantly lower in the leptin-treated animals, suggesting that the drop in UCP1 mRNA seen in the previous study had been translated to protein levels. In conclusion, the decline in plasma leptin levels at birth may be a signal to initiate enteral feeding. In lambs, the rapid loss of UCP1 mRNA, which occurs within the first few days of life, appears to be accelerated by leptin administration, possibly stimulating the development of white adipose tissue and generation of body heat through mechanisms other than non-shivering thermogenesis by UCP1 in BAT.

Adipose Tissue, Brown↗
PubMed2001

Organic and hydraulic shock loadings on a biological aerated filter.

The performance of a biological aerated filter (BAF) during short-term (60 min) organic and hydraulic shock loads was investigated. The BAF used for the present experiment was not capable of absorbing high peak organic shock loads when the organic loads were increased from a normal load of 1.2-1.4 kg soluble chemical oxygen demand (sCOD ) m(-3) d(-1) to shock loads between 5.1- 7.3 kg sCOD m(-3) d(-1), based on empty bed volumes. Nevertheless, the effect on the biomass was limited as normal performance resumed very quickly. Increases in the hydraulic velocity from 0.7-1.0 m h(-1) to 1.5-2.9 m h(-1) had little effect on BAF performance in terms of soluble COD removal. Yet, sCOD effluent concentrations of <55 mg l(-1) (approximately 22 mg l(-1) biochemical oxygen demand) were always achieved. The recovery of the reactor in both cases was fast, resuming normal performance within 60 min after the application of the shock load.

Biomass↗
PubMed2001

Catch-up growth in small-for-gestational-age term infants: a randomized trial.

BACKGROUND: Small-for-gestational-age (SGA) term infants are at risk of long-term growth deficits. OBJECTIVE: The objectives were to test the hypothesis that postnatal growth in SGA term infants can be altered by dietary intervention and to examine whether there is a critical window for nutritional programming of the growth trajectory during the first 9 mo postnatally. DESIGN: Healthy term (gestation > or =37 wk) infants with birth weights below the 10th centile were randomly assigned to receive standard term formula (TF; n = 147) or nutrient-enriched formula (EF; n = 152) for the first 9 mo; 175 breast-fed SGA term infants formed a reference group. The main outcome measures were weight, length, and occipitofrontal head circumference (OFC) at 9 and 18 mo. RESULTS: The infants fed the EF showed greater gains in length by 9 (1.1 cm; 95% CI: 0.38, 1.79) and 18 (1.0 cm; 0.25, 1.83) mo and in OFC by 9 (0.5 cm; 0.1, 0.9) and 18 (0.6 cm; 0.2, 1.1) mo than did infants fed the TF; the differences were larger in females. The dietary effects were independent of the pattern of growth retardation. Breast-fed infants showed greater gains in weight and OFC by 18 mo than did infants fed the TF; however, these differences disappeared after adjustment for age, parental size, and birth order. CONCLUSIONS: Linear growth and OFC gains in SGA term infants improve after nutritional intervention during the first 9 mo of life and the effects persist for > or =9 mo beyond the intervention period. Further information on whether catch-up growth is beneficial or detrimental to long-term outcomes is required before public health interventions can be recommended.

Analysis of Variance↗
PubMed2001

Effect of postnatal age and a beta(3)-adrenergic agonist (Zeneca D7114) administration on uncoupling protein-1 abundance in the lamb.

We examined the effect of time after birth and beta(3)-adrenergic agonist (Zeneca D7114) administration on uncoupling protein-1 (UCP1) abundance and thermoregulation in the lamb. Forty twin lambs, all born normally at term, were maintained at a cold ambient temperature of between 3 and 8 degrees C. At 0.5, 1.75, 5.25, 11.25 and 23.25 h after birth eight sets of twins were fed 20 ml of formula milk +/- 10 mg kg(-1) of beta(3)-adrenergic agonist, and 45 min after feeding brown adipose tissue (BAT) was sampled. Colonic temperature was measured and BAT analysed for UCP1 abundance, GDP-binding to mitochondrial protein (i.e. thermogenic activity) and catecholamine content. Colonic temperature declined between 1.25 and 6 h from 40.2 degrees C to 39.2 degrees C and then increased to 39.8 degrees C at 12 h, but increased after feeding at all ages. UCP1 abundance increased from 1.25 h after birth, to peak at 2 h after birth in controls, compared with 6 h after birth in beta(3)-adrenergic agonist-treated lambs. The level of GDP-binding to mitochondrial protein did not change significantly with age but was increased by beta(3)-adrenergic agonist treatment. The noradrenaline (norepinephrine) content of BAT increased between 1.25 and 12 h after birth, irrespective of beta(3)-adrenergic agonist administration. The total weight of perirenal BAT plus its lipid, protein and mitochondrial protein content declined over the first 6 h of life. UCP1 development continues over the first 24 h of neonatal life, and can be manipulated by beta(3)-adrenergic agonist administration. This may represent one method of improving thermoregulation in newborn lambs. Experimental Physiology (2001) 86.1, 65-70.

Adipose Tissue, Brown↗
PubMed2001

Determining the common medical presenting problems to an accident and emergency department.

All accident and emergency (A&E) attendances over a one year period were prospectively studied in order to determine common medical presenting problems. Data were collected on children (0-15 years) attending a paediatric A&E department in Nottingham between February 1997 and February 1998. A total of 38 982 children were seen. The diagnoses of 26 756 (69%) were classified as trauma or surgical, and 10 369 (27%) as medical; 1857 (4%) could not be classified. The commonest presenting problems reported for "medical" children were breathing difficulty (31%), febrile illness (20%), diarrhoea with or without vomiting (16%), abdominal pain (6%), seizure (5%), and rash (5%). The most senior doctor seeing these patients in A&E was a senior house officer (intern or junior resident) in 78% of cases, paediatric registrar (senior resident) in 19%, consultant (attending physician) in 1.4%, and "other" in 2.6%. Guidelines developed for A&E should target the commonest presenting problem categories, six of which account for 83% of all medical attendances, and be directed towards senior house officers.

Acute Disease↗
PubMed2001

An evidence and consensus based guideline for acute diarrhoea management.

OBJECTIVE: To develop an evidence and consensus based guideline for the management of the child who presents to hospital with diarrhoea (with or without vomiting), a common problem representing 16% of all paediatric medical attenders at an accident and emergency department. Clinical assessment, investigations (biochemistry and stool culture in particular), admission, and treatment are addressed. The guideline aims to aid junior doctors in recognising children who need admission for observation and treatment and those who may safely go home. EVIDENCE: A systematic review of the literature was performed. Selected articles were appraised, graded, and synthesised qualitatively. Statements on recommendation were generated. CONSENSUS: An anonymous, postal Delphi consensus process was used. A panel of 39 selected medical and nursing staff were asked to grade their agreement with the generated statements. They were sent the papers, appraisals, and literature review. On the second and third rounds they were asked to re-grade their agreement in the light of other panelists' responses. Consensus was predefined as 83% of panelists agreeing with the statement. RECOMMENDATIONS: Clinical signs useful in assessment of level of dehydration were agreed. Admission to a paediatric facility is advised for children who show signs of dehydration. For those with mild to moderate dehydration, estimated deficit is replaced over four hours with oral rehydration solution (glucose based, 200-250 mOsm/l) given "little and often". A nasogastric tube should be used if fluid is refused and normal feeds started following rehydration. Children at high risk of dehydration should be observed to ensure at least maintenance fluid is tolerated. Management of more severe dehydration is detailed. Antidiarrhoeal medication is not indicated. VALIDATION: The guideline has been successfully implemented and evaluated in a paediatric accident and emergency department.

Acute Disease↗
PubMed2001

Changes in molecular weight forms of inhibin A and pro-alpha C in maternal serum during human pregnancy.

Maternal serum pools obtained from healthy women throughout normal pregnancy were fractionated by a combined immunoaffinity chromatography, preparative PAGE, and electroelution procedure. Inhibin A and the pro-alpha C region of the inhibin alpha-subunit were determined in the eluted fractions by specific ELISAs, and the profiles of immunoactivity characterized in terms of molecular weight and percent recovery. The molecular weight patterns of inhibin A and pro-alpha C in serum during early pregnancy (<19 wk gestation) showed peaks between 25-40K and approximately 60K, consistent with the presence of known mature and larger precursor inhibin forms. However, during late pregnancy (>19 wk gestation), an increase in the proportion of smaller molecular weight forms (from 2% to approximately 25%) of inhibin A and pro-alpha C of unknown structure were observed in the less than 30K and less than 25K regions, respectively. To assess whether this change in molecular weight distribution in late pregnancy was related to the method of serum collection, serum and plasma from women during early and late pregnancy were collected and snap-frozen. Three pools [one from early pregnancy (12-15 wk), two from late pregnancy (28-39 wk)] of serum and plasma were then fractionated as described above. No differences in molecular weight patterns of inhibin A and pro-alpha C were observed between serum and plasma pools obtained in early pregnancy. However, in late pregnancy there was a reduction in the proportion of low molecular weight forms between serum (25% inhibin A, 35% pro-alpha C) and plasma (12% and 17%, respectively), but not to the low levels seen in early pregnancy. Incubation of iodinated 30K human inhibin A with serum or plasma obtained from early or late pregnancy showed no evidence of cleavage, suggesting that 30K inhibin A is not the cleavage precursor. It is speculated that the formation of small molecular weight forms of both inhibin A and pro-alpha C is attributed to proteolytic changes, in part induced in the circulation during late gestation and in part by the placenta before secretion. It is concluded that inhibin A and pro-alpha C are processed in late pregnancy by more than one mechanism to form low molecular weight circulating forms of unknown structure.

Chemical Fractionation↗
PubMed2001

Fetal endocrinology and development--manipulation and adaptation to long-term nutritional and environmental challenges.

This article reviews the fetal endocrine system in sheep, a species that has a long gestation and primarily produces a singleton fetus. Attention is focused on information that is applicable to humans. The endocrinology of metabolic homeostasis in sheep fetuses is well adapted to respond to a range of metabolic challenges, including placental restriction and maternal undernutrition. A small placenta results in hypoxaemia, hypoglycaemia, reduced abundance of anabolic hormones, and fetal growth restriction. Fetuses with restricted growth are characterized by tissue-specific reductions in hormone receptor mRNA, for example mRNA for the long form of prolactin receptor is reduced in adipose tissue. In contrast, the adipose tissue of fetuses with accelerated growth, stimulated by increasing maternal nutrition in the second half of gestation, has more protein for the long form of the prolactin receptor and more uncoupling protein 1, by which large amounts of heat are generated at birth. Maternal undernutrition in early gestation, coinciding with the period of rapid placental growth, initially restricts placental growth, but when mothers are fed to requirements, a longer fetus results with a disproportionately large placenta. This nutritional manipulation replicates, in part, epidemiological findings from the Dutch famine of 1944-1945, for which the offspring are at increased risk of adult obesity.

Animal Nutritional Physiological Phenomena↗
PubMed2001

Growth and development in preterm infants fed long-chain polyunsaturated fatty acids: a prospective, randomized controlled trial.

OBJECTIVES: A randomized, masked, controlled trial was conducted to assess effects of supplementing premature infant formulas with oils containing the long-chain polyunsaturated fatty acids, arachidonic acid (AA; 20:4 n6), and docosahexaenoic acid (DHA; 22:6 n3) on growth, visual acuity, and multiple indices of development. METHODS: Infants (N = 470) with birth weights 750 to 1800 g were assigned within 72 hours of the first enteral feeding to 1 of 3 formula groups with or without long-chain polyunsaturated fatty acids: 1) control (N = 144), 2) AA+DHA from fish/fungal oil (N = 140), and 3) AA+DHA from egg-derived triglyceride (egg-TG)/fish oil (N = 143). Infants were fed human milk and/or Similac Special Care with or without 0.42% AA and 0.26% DHA to term corrected age (CA), then fed human milk or NeoSure with or without 0.42% AA and 0.16% DHA to 12 months' CA. Infants fed exclusively human milk to term CA (EHM-T; N = 43) served as a reference. RESULTS: Visual acuity measured by acuity cards at 2, 4, and 6 months' CA was not different among groups. Visual acuity measured by swept-parameter visual-evoked potentials in a subgroup from 3 sites (45 control, 50 AA+DHA [fish/fungal]; 39 AA+DHA [egg-TG/fish]; and 23 EHM-T) was better in both the AA+DHA (fish/fungal; least square [LS] means [cycle/degree] +/- standard error [SE; octaves] 11.4 +/- 0.1) and AA+DHA (egg-TG/fish; 12.5 +/- 0.1) than control (8.4 +/- 0.1) and closer to that of the EHM-T group (16.0 +/- 0.2) at 6 months' CA. Visual acuity improved from 4 to 6 months' CA in all but the control group. Scores on the Fagan test of novelty preference were greater in AA+DHA (egg-TG/fish; LS means +/- SE, 59.4 +/- 7.7) than AA+DHA (fish/fungal; 57.0 +/- 7.5) and control (57.5 +/- 7.4) at 6 months' CA, but not at 9 months' CA. There were no differences in the Bayley Mental Development Index at 12 months' CA. However, the Bayley motor development index was higher for AA+DHA (fish/fungal; LS means +/- SE, 90.6 +/- 4.4) than control (81.8 +/- 4.3) for infants </=1250 g. When Spanish-speaking infants and twins were excluded from the analyses, the MacArthur Communicative Development Inventory revealed that control infants (LS means +/- SE, 94.1 +/- 2.9) had lower vocabulary comprehension at 14 months' CA than AA+DHA (fish/fungal) infants (100.6 +/- 2.9) or AA+DHA (egg-TG/fish) infants (102.2 +/- 2.8). There were no consistent differences in weight, length, head circumference, or anthropometric gains. CONCLUSION: These results showed a benefit of supplementing formulas for premature infants with AA and DHA from either a fish/fungal or an egg-TG/fish source from the time of first enteral feeding to 12 months' CA.

Apgar Score↗
PubMed2001

Randomized trial of nutrient-enriched formula versus standard formula for postdischarge preterm infants.

OBJECTIVES: Preterm infants are frequently discharged from the hospital growth retarded and show reduced growth throughout childhood. In a large efficacy and safety trial, we tested the hypothesis that nutritional intervention in the first 9 months postterm would reverse postdischarge growth deficits and improve neurodevelopment without adverse safety outcomes. PARTICIPANTS AND INTERVENTION: Two hundred eighty-four infants (mean gestation: 30.9 weeks) were studied; 229 were randomly assigned a protein, energy, mineral, and micronutrient-enriched postdischarge formula (PDF; N = 113) or standard term formula (TF; N = 116) from discharge (mean 36.5 weeks' postmenstrual age). A reference group (N = 65) was breastfed until at least 6 weeks' postterm. Outcome measures. Anthropometry was performed at 6 weeks and 3, 6, 9, and 18 months. Development was measured at 9 months (Knobloch, Passamanick, and Sherrard's developmental screening inventory) and 18 months (Bayley Scales of Infant Development II; primary outcome) postterm. RESULTS: At 9 months, compared with the TF group, those fed PDF were heavier (difference 370 g; 95% confidence interval [CI]: 84-660) and longer (difference 1.1 cm; 95% CI: 0.3-1.9); the difference in length persisted at 18 months (difference 0.82 cm; 95% CI: -0.04-1.7). There was no effect on head circumference. The effect of diet was greatest in males; at 9 months length deficit with TF was 1.5cm (95% CI: 0.3-2.7), and this remained at 18 months (1.5cm [95% CI: 0.3-2.7]). There was no significant difference in developmental scores at 9 or 18 months, although PDF infants had a 2.8 (-1.3-6.8) point advantage in Bayley motor score scales. At 6 weeks' postterm, exclusively breastfed infants were already 513 g (95% CI: 310-715) lighter and 1.6cm (95% CI: 0.8-2.3) shorter than the PDF group, and they remained smaller up to 9 months' postterm. CONCLUSIONS: 1) Improving postdischarge nutrition in the first 9 months may "reset" subsequent growth-at least until 18 months for body length. We intend to follow-up the children at older ages. The observed efficacy of PDF was not associated with adverse safety outcomes. 2) We cannot reject the hypothesis that postdischarge nutrition benefits motor development and this requires additional study. 3) Our data raise the possibility that breastfed postdischarge preterm infants may require nutritional supplementation, currently under investigation.

Anthropometry↗
PubMed2001

Advanced biological unit processes for domestic water recycling.

The potential of advanced biological unit operations for the recycling of grey and black waters has been evaluated. The membrane bioreactor (MBR) demonstrated the greatest efficacy towards water recycling in terms of all the quality determinants. Both the biologically aerated filter (BAF) and the MBR were able to effectively treat the organic and physical pollutants in all the types of wastewater tested. The main difference was observed in terms of the microbiological quality, measured as total coliforms. The open bed structure of the BAF enabled passage of coliforms whereas the complete barrier of the MBR produced a non detectable level in the effluent. The MBR process complied with commonly adopted water recycling quality standards for the all determinants during the grey water trials and failed only in terms of total coliform counts once black water had been introduced into the feed. The MBR was seen as a particularly suitable advanced biological process as it was very effective at stabilising out the considerable load variations encountered during the trial.

Bioreactors↗
PubMed2001

Small scale water recycling systems--risk assessment and modelling.

This paper aims to use quantitative risk analysis, risk modelling and simulation modelling tools to assess the performance of a proprietary single house grey water recycling system. A preliminary Hazard and Operability study (HAZOP) identified the main hazards, both health related and economic, associated with installing the recycling system in a domestic environment. The health related consequences of system failure were associated with the presence of increased concentrations of micro-organisms at the point of use, due to failure of the disinfection system and/or the pump. The risk model was used to assess the increase in the probability of infection for a particular genus of micro-organism, Salmonella spp, during disinfection failure. The increase in the number of cases of infection above a base rate rose from 0.001% during normal operation, to 4% for a recycling system with no disinfection. The simulation model was used to examine the possible effects of pump failure. The model indicated that the anaerobic COD release rate in the system storage tank increases over time and dissolved oxygen decreases during this failure mode. These conditions are likely to result in odour problems.

Conservation of Natural Resources↗
PubMed2001

Municipal wastewater sludge dewaterability and the presence of microbial extracellular polymer.

Dewatering of sewage sludge is an essential and costly part of the wastewater treatment process. The presence of microbial extracellular polymer (ECP) is important for sludge flocculation, but ECP has also been shown to have a detrimental effect on the dewaterability of certain sludge types. This paper investigates the relationship between sludge dewaterability and the level of ECP present in a range of sludges obtained from 8 full-scale municipal treatment works in the UK. Sludge dewaterability was determined using the capillary suction time (CST) test, and a thermal extraction process followed by solvent precipitation was used for ECP extraction. The results indicate that for each type of sludge examined there appears to be an optimum level of ECP (raw sludge 20 mg ECP/g SS; activated sludge 35 mg ECP/g SS; digested sludge 10 mg ECP/g SS) at which the sludge should exhibit maximum dewaterability. The establishment of a trend between sludge dewaterability and the quantity of ECP present opens up the possibility of manipulating the level of microbial polymer present to aid sludge dewatering, and hence reduce plant operating costs.

Flocculation↗
PubMed2001

Maternal nutritional manipulation of placental growth and glucose transporter 1 (GLUT-1) abundance in sheep.

Glucose transporter 1 (GLUT-1) is the predominant glucose transporter in the placenta but the extent to which its abundance is nutritionally regulated is unknown. This study investigated the effects of restricted maternal nutrition between day 28 and day 80 of gestation followed by re-feeding to either meet or to exceed the total energy requirements on placental size and GLUT-1 abundance at mid-gestation (that is, day 80) and near to term (that is, days 140-145 of gestation; term = 147 days). Singleton bearing ewes either consumed 8.7-9.9 MJ day(-1) of metabolizable energy (that is, well fed) or 3.2-3.8 MJ day(-1) of metabolizable energy (that is, nutrient restricted) from day 28 to day 80 of gestation, after which stage they consumed either 6.5-7.5 MJ day(-1) (that is, adequately fed) or 8.0-10.9 MJ day(-1) (that is, well fed) of metabolizable energy until near to term. In all ewes, at both sampling dates, the abundance of GLUT-1 was higher in the maternal component than in the fetal component of the placenta. Immunohistochemistry confirmed that GLUT-1 was located in the maternal uterine syncytium. At day 80 of gestation, placental mass was lower (P < 0.05) in the nutrient restricted group, but there was no difference in the abundance of GLUT-1 between the nutrient restricted group and the well fed group. At near term, placental mass was greater (P < 0.05) in ewes that were nutrient restricted during early to mid-gestation and then adequately fed up to term compared with ewes that were well fed during early to mid-gestation. This increase was associated with a higher (P < 0.05) abundance of total placental GLUT-1 and a larger fetus. There was no effect of previous nutrient restriction on placental mass, fetal weight or GLUT-1 abundance at term, when ewes were well fed in the second half of gestation. In conclusion, maternal nutrient restriction between early to mid-gestation alters placental growth but has no effect on placental GLUT-1 abundance. Increasing maternal feed intake to meet calculated energy requirements in previously nutrient restricted ewes during the second half of gestation, increases placental mass and fetal weight, and the abundance of GLUT-1, an adaptation not observed if maternal food intake is increased above requirements.

Analysis of Variance↗