Maturation of feedback control of thyrotropin in premature infants

Serum thyrotropin (TSH), free T4 and free T3 concentrations were measured longitudinally in 26 preterm infants for 14 weeks after birth, using highly sensitive immunoradiometric assays. Serum TSH values on days 4-5 were positively correlated with gestational age and birth weight. In the premature infants of 25 weeks mean gestation, the mean TSH concentrations increased from a very low value of 0.84 microU/ml at 5 days to a peak value of 6.1 microU/ml by 5 weeks of age, then slightly decreased and remained stable. Serum free T4 and free T3 concentrations increased in parallel and free T3 level reached the range of term infants by 6 weeks. Serum free T4/TSH and free T3/TSH ratios began to increase at the 6th week of age. The results suggest that: (i) the thyroid hormone feedback control of pituitary TSH release in the extremely premature infants begins to mature after 6 weeks of postnatal age, (ii) the maturation pattern of the hypothalamic-pituitary-thyroid system in premature infants is similar to that of the intrauterine fetus.     

Blood pressure survey in a population of newborn infants.

Systolic blood pressure in the arm was measured in infants at the ages of 4 to 6 days and 5 to 7 weeks by the Doppler ultrasound technique. At the age of 4 to 6 days the mean blood pressure (+/- SE of mean) in 469 sleeping infants was 70-7 +/- 0-3 mm Hg, rising at 5 to 7 weeks to 89-7 +/- 0-9 mm Hg (in 144 infants). In 252 infants awake at 5 to 7 weeks blood pressure was 96-8 +/- 0-6 mm Hg. In 391 infants in whom measurements were made on both occasions blood pressure at 4 to 6 days was significantly related to blood pressure at 5 to 7 weeks. Thus those infants with relatively high blood pressures at 4 to 6 days showed a weak tendency to have relatively high blood pressures at 5 to 7 weeks. In this trend continues with age it would suggest that the tendency to develop hypertension may already be demonstrable at the age of 4 to 6 days.     

Four-Month-Old Infants’ Long-Term Memory for a Stressful Social Event

Infants clearly show an early capacity for memory for inanimate emotionally neutral events. However, their memory for social stress events has received far less attention. The aim of the study was to investigate infants’ memory for a stressful social event (i.e., maternal unresponsiveness during the Still-Face paradigm) after a 15-day recall interval using changes in behavioral responses and salivary post-stress cortisol reactivity as measures of memory. Thirty-seven infants were exposed to social stress two times (experimental condition); the first time when they were 4 months of age and second exposure after a 2 week interval. Infants in the control condition (N = 37) were exposed to social stress just one time, at the age corresponding to the second exposure for infants in the experimental condition (4 months plus 2 weeks). Given individual differences in infants’ reactivity to social stress events, we categorized infants as increasers or decreasers based on their cortisol reactivity after their initial exposure to the stress of the maternal still-face. Infants in the experimental condition, both increasers and decreasers, showed a significant change in cortisol response after the second exposure to the maternal still-face, though change was different for each reactivity group. In contrast, age-matched infants with no prior exposure to the maternal still-face showed similar post-stress cortisol reactivity to the reactivity of the experimental infants at their first exposure. There were no behavioral differences between increasers and decreasers during the Still-Face paradigm and exposures to the social stress. Thus differences between the experimental and control groups’ post-stress cortisol reactivity was associated with the experimental group having previous experience with the social stress. These findings indicate long-term memory for social stress in infants as young as 4 months of age.     

Results of surgical treatment for extrahepatic biliary atresia in United Kingdom 1980-2. Survey conducted on behalf of the British Paediatric Association Gastroenterology Group and the British Association of Paediatric Surgeons.

A postal survey identified 114 infants with biliary atresia (roughly one in 21 000 live births). Biliary operations were performed on 107. Of the 105 infants who were followed up, 35 were free of jaundice at 10 months to 3 1/2 years. Good results occurred most often in those operated on by 12 weeks and were also related to the number of cases operated on in each centre. Only two of 18 infants treated in centres dealing with one case a year were free of jaundice compared with 11 of 38 at centres treating two to five cases a year and 22 of 49 in a centre treating more than five cases a year. Jaundice in an infant of more than 2 weeks associated with yellow urine or pale stools is never physiological and requires urgent investigation to identify causes for which effective treatment may be possible. Identification of suspected cases by 4 weeks of age and a greater concentration of investigative and surgical skills should improve the short term results of surgery and the long term prognosis of biliary atresia.     

Tolerance and safety evaluation in a large cohort of healthy infants fed an innovative prebiotic formula: a randomized controlled trial

Background

the addition of oligosaccharides to infant formula has been shown to mimic some of the beneficial effects of human milk. The aim of the study was to assess the tolerance and safety of a formula containing an innovative mixture of oligosaccharides in early infancy.

Methodology/Principal Findings

this study was performed as a multi-center, randomized, double-blind, placebo-controlled trial including healthy term infants. Infants were recruited before the age of 8 weeks, either having started with formula feeding or being fully breast-fed (breastfeeding group). Formula-fed infants were randomized to feeding with a regular formula containing a mixture of neutral oligosaccharides and pectin-derived acidic oligosaccharides (prebiotic formula group) or regular formula without oligosaccharides (control formula group). Growth, tolerance and adverse events were assessed at 8, 16, 24 and 52 weeks of age. The prebiotic and control groups showed similar mean weight, length and head circumference, skin fold thicknesses, arm circumference gains and stool frequency at each study point. As far as the anthropometric parameters are concerned, the prebiotic group and the control group did not attain the values shown by the breastfeeding group at any study point. The skin fold thicknesses assessed in the breastfeeding group at 8 weeks were strikingly larger than those in formula fed infants, whereas at 52 weeks were strikingly smaller. The stool consistency in the prebiotic group was softer than in the control group at 8, 16 and 24 weeks (p<0.001) and closer to that of the breastfeeding group. There was no difference in the incidence of adverse events between the two formula groups.

Conclusions

our findings demonstrate the tolerability and the long term safety of a formula containing an innovative mixture of oligosaccharides in a large cohort of healthy infants.

Trial Registration:

drks-neu.uniklinik-freiburg.de DRKS 00000201     

The laboratory diagnosis of cytomegalovirus infection in infants in the first months of life

The detection rate of IgM, specific to cytomegalovirus (CMV), in the umbilical blood was 2.0 +/- 1.8% in infants with antenatal complications in their medical history, 8.9 +/- 1.8% in hospitalized infants aged 7 days to 6 months; simultaneously, such IgM proved to be absent in healthy infants of the same age. The maximum primary detection rate of CMV-specific IgM in hospitalized infants was registered at the age of 1.5-4 months and the minimum detection rate, at the age of 6 months, as well as at the age of 1 month and younger. In sick infants aged 0-6 months CMV-specific IgM were detected, as a rule, for 2-4 weeks. 86% of infants with CMV-specific IgM detected in their blood were found to have cytomegaloviremia; in 80% of patients the virus was excreted with saliva and in 50% the virus was detected in blood plasma.     

Serum PAF acetylhydrolase increases during neonatal maturation

Acetylhydrolase is an acid-labile, 43 kd protein that catalyzes the degradation of platelet activating factor (PAF), a potent phospholipid inflammatory mediator, to its biologically inactive metabolite lysoPAF. PAF has a short half-life, thus acetylhydrolase plays an important role in its regulation. Since previous work suggests that PAF may be involved in certain neonatal diseases such as necrotizing enterocolitis, we studied the effect of age on acetylhydrolase activity. Serum acetylhydrolase activity was quantified using radio-labelled PAF and measuring reaction products. Serum samples were obtained prospectively from 70 subjects ranging in age from 4 hr to 48 yr. Acetylhydrolase activity was lower for newborns (less than 3 wk) than all other age ranges (8.2 +/- 1.4 nmole/ml/min vs 30.0 +/- 1.6 nmole/ml/min, p less than .01). Furthermore, enzyme activity increased linearly with respect to the natural logarithm of age from 0 days to 6 weeks (r = 0.65, p less than .001). By 6 weeks of life acetylhydrolase activity approached values of older children and adults. Newborn acetylhydrolase activity was similar between term and preterm infants (8.6 +/- 1.9 nmole/ml/min vs 7.2 +/- 2.4 nmole/ml/min, p = NS). We conclude that acetylhydrolase activity is low in human neonates and increases during the first 6 weeks of life. These results suggest that newborn infants may be at increased risk for pathophysiologic processes mediated by PAF.     

Plasma selenium in preterm and term infants during the first 12 months of life

The goal of the present study was to prospectively assess the plasma selenium (Se) concentrations of term and preterm infants during the first year of life in relation to gestational age and nutrition.

Blood specimens were collected from orally formula-fed preterm infants (gestational age < 32 weeks, birth weight < 1500 g): 1.) in hospital and 2.) corrected for gestational age parallel to healthy term breast and formula-fed infants at the ages of 1, 4 and 12 months. All infants were fed according to a standardized nutritional concept, solids and follow-up formula were introduced at the age of 4 months.

Plasma selenium in preterm infants in hospital was 11.7 (6.5–20.8) g/l and 11.6 (8.8–16.7) g/l at 4 weeks corrected for gestational age. At the age of 4 months plasma selenium was still significantly lower than in the other groups: Preterm infants: 17.1 (10.4–30.5) g/l; formula-fed term infants: 31.3 (24.3–47.5) g/l; breast-fed term infants: 45.6 (27.1–65.1) g/l). The levels of breast-fed infants were significantly higher than those of both formula-fed groups up until the introduction of solids.

Preterm infants had significantly low plasma selenium levels up until a postnatal age of at least 6 months. The levels were lower than those of term infants fed an identical unsupplemented infant formula during the first 4 months of life. These data support routine monitoring in hospital and selenium supplementation of preterm infants, preferably in hospital before discharge.     

Thyrotropin measured by the immunoradiometric assay in low birth weight infants

In 37 infants, the blood levels of TSH were determined by the immunoradiometric assay (IRMA) and the relation between TSH and thyroid hormone was evaluated. The ranges of gestational age (weeks) and birth weight (g) of infants were 28-42 and 982-3,650, respectively. The birth weights of 19 infants were below 2,500 g. The free T4 levels in the low birth weight (LBW) infants were lower than those of the normal infants and significantly correlated to the birth weight (r = 0.64, P less than 0.01) and gestational age (r = 0.58, P less than 0.01). In addition, free T4 levels were significantly correlated to the levels of total T4 (r = 0.66, P less than 0.01). The concentrations of TSH measured by IRMA method were significantly correlated to those of free T4 (r = 0.51, P less than 0.01). From these data, we consider that the transient hypothyroxinemia observed frequently in LBW infants might be a physiological reaction regulated by hypothalamus and that thyroid hormone treatment should be avoided.     

Transmission of experimentally-induced rat virus infection

The duration of transmission of rat virus (RV) infection was determined using Sprague-Dawley rats inoculated oronasally as juveniles (4 weeks old) or as infants (2 days old). Contact transmission from rats inoculated as juveniles was detected for 3 weeks, whereas transmission from rats inoculated as infants occurred for 10 weeks. Transmission continued for at least 7 weeks after seroconversion occurred in rats inoculated as infants. Two of three rats that had ceased to transmit infection harbored infectious virus as detected by explantation of kidney. Intrauterine transmission occurred only after pregnant dams were inoculated with large doses of virus and was more efficient when virus was inoculated intravenously than by the oronasal route. Enzyme immunoassay antibody titers to RV in offspring of previously infected dams decreased steadily during the first 13 weeks of life and 27 of 29 offspring tested by immunofluorescence assay at 12 or 13 weeks of age were seronegative. These results indicate that RV was transmitted by rats inoculated as infants for long periods after seroconversion occurred. They also suggest that the offspring of previously-infected dams were not infected. In utero transmission of RV-Y is unlikely to occur after oronasal inoculation unless rats are exposed to large doses of virus.     

不同胎龄早产儿早期凝血指标的变化及其临床意义

目的:研究不同胎龄早产儿早期凝血指标的变化及其临床意义。方法:选取2012年1月至2017年7月期间我院出生的新生儿392例为研究对象。根据新生儿胎龄的不同分为早期早产儿组(胎龄27~31周)78例、中期早产儿组(胎龄32~33周)102例、晚期早产儿组(胎龄34~36周)116例以及足月新生儿组(胎龄37~42周)96例。四组新生儿出生后2h内抽取静脉血检测凝血指标,包括凝血酶原时间(PT)、活化部分凝血酶原时间(APTT)、纤维蛋白原(FIB),并应用Pearson相关性分析分析新生儿胎龄与上述各项凝血指标水平的相关性。结果:早期早产儿组、中期早产儿组、晚期早产儿组、足月新生儿组的出生体重以及胎龄呈逐渐上升趋势,不同组别新生儿的出生体重以及胎龄差异均有统计学意义(P0.05)。早期早产儿组、中期早产儿组、晚期早产儿组、足月新生儿组PT、APTT均呈逐渐下降趋势,FIB呈逐渐上升趋势,不同组别新生儿PT、APTT、FIB差异均有统计学意义(P0.05)。Pearson相关性分析显示,新生儿胎龄与PT、APTT呈负相关(r=-0.567、-0.691,P=0.000、0.000),而新生儿胎龄与FIB水平呈正相关(r=0.623,P=0.000)。结论:不同胎龄早产儿早期凝血功能存在异常变化,新生儿胎龄与PT、APTT均呈负相关关系,与FIB呈正相关关系,临床应予以重视,及时检测其凝血指标,必要时应予以干预治疗。     

Relation between early introduction of solid food to infants and their weight and illnesses during the first two years of life.

OBJECTIVE--To assess the relations between early introduction of solid food and infant weight, gastrointestinal illness, and allergic illnesses during the first two years of life. DESIGN--Prospective observational study of infants followed up for 24 months after birth. SETTING--Community setting in Dundee. PATIENTS--671 newborn infants, of whom 455 were still available for study at 2 years of age. MAIN OUTCOME MEASURES--Infants'' diet, weight, and incidence of gastrointestinal illness, respiratory illness, napkin dermatitis, and eczema at 2 weeks and 2, 3, 4, 6, 9, 12, 15, 18, 21, and 24 months of age. RESULTS--The infants given solid food at an early age (at < 8 weeks or 8-12 weeks) were heavier than those introduced to solids later (after 12 weeks) at 4, 8, 13, and 26 weeks of age (p < 0.01) but not at 52 and 104 weeks. At their first solid feed those given solids early were heavier than infants of similar age who had not yet received solids. The incidence of gastrointestinal illness, wheeze, and nappy dermatitis was not related to early introduction of solids. There was a significant but less than twofold increase in respiratory illness at 14-26 weeks of age and persistent cough at 14-26 and 27-39 weeks of age among the infants given solids early. The incidence of eczema was increased in the infants who received solids at 8-12 weeks of age. CONCLUSION--Early introduction of solid food to infants is less harmful than was previously reported. Longer follow up is needed, but, meanwhile, a more relaxed approach to early feeding with solids should be considered.     

Serum PAF acetylhydrolase increases during neonatal maturation

Acetylhydrolase is an acid-labile, 43 kd protein that catalyzes the degradation of platelet activating factor (PAF), a potent phospholipid inflammatory mediator, to its biologically inactive metabolite lysoPAF. PAF has a short half-life, thus acetylhydrolase plays an important role in its regulation. Since previous work suggests that PAF may be involved in certain neonatal diseases such as necrotizing enterocolitis, we studied the effect of age on acetylhydrolase activity. Serum acetylhydrolase activity was quantified using radio-labelled PAF and measuring reaction products. Serum samples were obtained prospectively from 70 subjects ranging in age from 4 hr to 48 yr. Acetylhydrolase activity was lower for newborns (< 3 wk) than all other age ranges (8.2 ± 1.4 nmole/ml/min vs 30.0 ± 1.6 nmole/ml/min, p < .01). Furthermore, enzyme activity increased linearly with respect to the natural logarithm of age from 0 days to 6 weeks (r = 0.65. p < .001). By 6 weeks of life acetylhydrolase activity approached values of older children and adults. Newborn acetylhydrolase activity was similar between term and preterm infants (8.6 ± 1.9 nmole/ml/min vs 7.2 ± 2.4 nmole/ml/min, p = NS). We conclude that acetylhydrolase activity is low in human neonates and increases during the first 6 weeks of life. These results suggest that newborn infants may be at increased risk for pathophysiologic processes mediated by PAF.     

Lactobacilli in the intestinal microbiota of Swedish infants

Lactobacillus colonisation was examined in 112 Swedish infants. Faecal samples obtained at 1, 2, 4 and 8 weeks and at 6, 12 and 18 months of age were cultivated quantitatively on Rogosa agar. Lactobacilli were speciated by PCR and typed to the strain level by randomly amplified polymorphic DNA (RAPD). Lactobacilli reached a peak at 6 months when 45% of the infants were colonised. L. rhamnosus and L. gasseri were the most common species in this period. Colonisation by lactobacilli in general (P < 0.01) and L. rhamnosus in particular (P < 0.05) was more common in breast-fed than in weaned infants at 6 months of age. Lactobacillus isolation reached a nadir of 17% by 12 months (P < 0.0001), but increased to 31% by 18 months of age P < 0.05). The food-related species L. paracasei, L. plantarum, L. acidophilus and L. delbrueckii dominated in this second phase. A single strain persisted for at least 3 weeks in 17% of the infants during the first 6 months, most commonly L. rhamnosus. Lactobacillus population counts in colonised infants increased from 10(6.4) cfu/g at 1 week to 10(8.8) cfu/g at 6 months, and then dropped to 10(5.4) cfu/g faeces at 12 months of age. Lactobacillus colonisation was not significantly related to delivery mode, or to presence of siblings or pets in the household. Our results suggest that certain Lactobacillus species, especially L. rhamnosus, thrive in the intestinal flora of breast-fed infants. After weaning they are replaced by other Lactobacillus species of types found in food.     

Maturation of the pituitary-thyroid axis during the perinatal period.

To clarify the maturation process of the pituitary-thyroid axis during the perinatal period, thyrotropin (TSH) response to thyrotropin releasing hormone (TRH) and serum thyroid hormone levels were examined in 26 healthy infants of 30 to 40 weeks gestation. A TRH stimulation test was performed on 10 to 20 postnatal days. Basal concentrations of serum thyroxine (T4), free thyroxine (free T4) and triiodothyronine (T3) were positively correlated to gestational age and birth weight (p less than 0.001-0.01). Seven infants of 30 to 35 gestational weeks demonstrated an exaggerated TSH response to TRH (49.7 +/- 6.7 microU/ml versus 22.1 +/- 4.8 microU/ml, p less than 0.001), which was gradually reduced with gestational age and normalized after 37 weeks gestation. A similar decrease in TSH responsiveness to TRH was also observed longitudinally in all of 5 high responders repeatedly examined. There was a negative correlation between basal or peak TSH concentrations and postconceptional age in high responders (r = -0.59 p less than 0.05, r = -0.66 p less than 0.01), whereas in the normal responders TSH response, remained at a constant level during 31 to 43 postconceptional weeks. On the other hand, there was no correlation between basal or peak TSH levels and serum thyroid hormones. These results indicate that (1) maturation of the pituitary-thyroid axis is intrinsically controlled by gestational age rather than by serum thyroid hormone levels, (2) hypersecretion of TSH in preterm infants induces a progressive increase in serum thyroid hormones, and (3) although there is individual variation in the maturation process, the feedback regulation of the pituitary-thyroid axis matures by approximately the 37th gestational week.     

Long-Range Correlations in Rectal Temperature Fluctuations of Healthy Infants during Maturation

Background

Control of breathing, heart rate, and body temperature are interdependent in infants, where instabilities in thermoregulation can contribute to apneas or even life-threatening events. Identifying abnormalities in thermoregulation is particularly important in the first 6 months of life, where autonomic regulation undergoes critical development. Fluctuations in body temperature have been shown to be sensitive to maturational stage as well as system failure in critically ill patients. We thus aimed to investigate the existence of fractal-like long-range correlations, indicative of temperature control, in night time rectal temperature (T_rec) patterns in maturing infants.

Methodology/Principal Findings

We measured T_rec fluctuations in infants every 4 weeks from 4 to 20 weeks of age and before and after immunization. Long-range correlations in the temperature series were quantified by the correlation exponent, α using detrended fluctuation analysis. The effects of maturation, room temperature, and immunization on the strength of correlation were investigated. We found that T_rec fluctuations exhibit fractal long-range correlations with a mean (SD) α of 1.51 (0.11), indicating that T_rec is regulated in a highly correlated and hence deterministic manner. A significant increase in α with age from 1.42 (0.07) at 4 weeks to 1.58 (0.04) at 20 weeks reflects a change in long-range correlation behavior with maturation towards a smoother and more deterministic temperature regulation, potentially due to the decrease in surface area to body weight ratio in the maturing infant. α was not associated with mean room temperature or influenced by immunization

Conclusions

This study shows that the quantification of long-range correlations using α derived from detrended fluctuation analysis is an observer-independent tool which can distinguish developmental stages of night time T_rec pattern in young infants, reflective of maturation of the autonomic system. Detrended fluctuation analysis may prove useful for characterizing thermoregulation in premature and other infants at risk for life-threatening events.     

Hypoglycemia of squirrel monkey neonates: implications for infant survival

Neonatal deaths are a serious problem in breeding colonies of squirrel monkeys. Seriously ill neonates in our colony are always hypoglycemic on presentation. To determine normal glucose values for squirrel monkey infants of various ages, serum glucose determinations were done at 1, 3, 7, 10, 14 days and 1 month of age using a standard laboratory test for serum glucose. Glucose concentration increased from a low of 49 +/- 3 mg/dl (Mean +/- SEM) at 1 day (n = 21) to 109 +/- 4 mg/dl at 1 month of age (n = 17). Glucose values for 1, 3 and 7 day-old infants were significantly lower than 1 month-old infants (P less than .05). To provide a time-averaged indication of blood glucose, glycosylated hemoglobin (GHb) measurements were made at 1 day, 1 week, 2 weeks, 1 month, 2 months, 1 year of age and in adults (greater than 3 years of age). GHb values ranged from 2.6% +/- 0.1 for 1 day old infants (n = 13) to 4.0 +/- 0.2 for adults (n = 10) with a steady increase during the first 2 months of life. Animals 1 year of age and younger had significantly lower glycosylated hemoglobin than adults. These studies indicate that blood glucose concentration is significantly lower in squirrel monkey neonates than in older infants, juveniles and adults. Maternal rejection, trauma, and associated problems occur commonly in socially reared squirrel monkeys. The marginal hypoglycemic state of these infants places them at high risk for clinical hypoglycemia as a sequel to such perturbations.     

Investigation of the intestinal microbiota in preterm infants using different methods

Modifications in microbial colonization of the human gut are believed to affect intestinal homeostasis and increase the risk of gastrointestinal diseases. The present study examined different methods for investigating the dynamic characterization of the intestinal microbiota in preterm infants. Fecal samples were collected weekly from ten preterm infants during their stay in a neonatal intensive care unit. The infants had a mean gestational age of 29 weeks (range: 28–32 weeks) and a mean birth weight of 1233 g (range: 935–1450 g). Bacterial colonization was assessed using conventional culture techniques and molecular biological methods. More specifically, the recently developed denaturing high performance liquid chromatography (dHPLC) technique was compared to established methods such as temporal temperature gradient gel electrophoresis (TTGE) and rRNA gene library sequencing. Our results indicate that the gastrointestinal tract of preterm infants, born at a gestational age of less than 33 weeks, has a low biodiversity of mainly, culturable bacteria. Finally, dHPLC was evaluated in terms of speed, labor and sensitivity for its use as a tool to analyze microbial colonization in preterm infants. We found that this technique provided major improvements over gel-based fingerprinting methods, such as TTGE, that are commonly used for studying microbial ecology. As such, it may become a common analytical tool for this purpose.     

Longitudinal body composition data in exclusively breast-fed infants: a multicenter study

Reference %fat and total fat-free mass data is necessary for evaluating growth in infants. We aimed to develop longitudinal %fat and total fat-free mass data in infants from birth to 6 months of age. An observational, multicenter, prospective cohort study was conducted with assessments at birth, 1 week, 2 weeks, 1, 2, 3, 4, 5, and 6 months of age. Subjects were exclusively breast-fed and were enrolled at three centers. Whole-body composition (i.e., % fat and total fat-free mass) were assessed using air-displacement plethysmography (ADP) (PEA POD; Life Measurement, Concord, CA). Maternal prepregnancy BMI, gestational weight gain, and infant anthropometric data were collected. A total of 160 infants (boys = 84) were assessed from birth to 4 months of age. Mean birth weight was 3.46 ± 0.39 kg % fat and fat-free mass significantly increased from birth to 4 months of age (P < 0.0001). Gender-specific %fat and total fat-free mass curves for infants from birth to 4 months of age were created. This study will be beneficial to health-care professionals in evaluating normal growth and nutritional patterns in the first months of life.     

The effect of gestational age and labour on markers of lipid and protein oxidation in cord plasma

There are many potential sources of reactive oxidants around the time of birth and pre-term infants are considered to be particularly vulnerable to oxidative injury. To gain insight into these processes, we have measured biomarkers of lipid and protein oxidation in umbilical cord plasma and related concentrations to mode of delivery and gestational age. Protein carbonyls were measured by ELISA and malondialdehyde (MDA) by HPLC after reaction with thiobarbituric acid, for 54 pre-term (< or = 36 weeks gestational age) and 43 term infants. Protein carbonyls were significantly lower in pre-term (median for < 32 weeks gestational age 0.048nmol/mg protein) than in term infants (0.105 nmol/mg, p = 0.004), and were unrelated to mode of delivery. In contrast, MDA concentrations were higher in the very pre-term (<32 weeks gestation) group (2.47 compared with 1.83 microM for term infants, p < 0.0001). MDA concentrations were higher in infants who were born with labour compared with elective caesarean section. Pre-eclampsia in the mother was associated with higher cord blood MDA concentrations. The MDA results are consistent with other studies of this marker and could be interpreted as indicating increased oxidative stress associated with prematurity and labour. However, the lower protein carbonyls in pre-term infants would lead to an opposite interpretation. More information is needed on the source and fate of these and other biomarkers before drawing strong conclusions on how they reflect oxidative stress in this and other clinical situations.