Neonatal society abstracts — Summer 2005, Bristol

Early Human Development (2006) 82, 609 — 622

available at www.sciencedirect.com

www.elsevier.com/locate/earlhumdev

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Neonatal society abstracts — Summer 2005, Bristol Thursday 30th June 12:00

Registration and Lunch

Chairman: Professor Andrew Wilkinson, President of the Neonatal Society 12:55

Welcome

13:00

Young Investigator Prize Lecture: Human Mesenchymal Stem Cells as Agents of Brain Repair Dr Nigel Kennea Wellcome Training Fellow Hammersmith Hospital Imperial College London

13:45

Dr U Sothinathan, Kings College Hospital Are we missing something? Detection of infants at risk of congenital syphilis their treatment and follow-up

14:00

Dr Edile Murdoch, Addenbrookes Hospital Neonatal necrotizing enterocolitis is associated with high resistance flow in the superior mesenteric artery on day 1 of life in preterm infants

14:15

Dr Rose-Marie Mackay, University of Oxford A recombinant fragment of human SP-D promotes phagocytosis of Haemophilus influenzae strains whose in vivo pathogenicity is inversely related to SP-D binding

14:30

Keynote Lecture: What has the Human Genome Project done for Neonatology? Professor Mark Gardiner Professor of Paediatrics and Child Health University College London

15:30—16:00

Tea

Chairman: Dr Nikki Robertson, Meetings Secretary of the Neonatal Society 16:00

Dr Bazarragchaa Tsogt, University of Bristol The development of thermoregulation in a harsh environment: A prospective controlled study of the effects of swaddling on infants’ thermal balance in a Mongolian winter

doi:10.1016/j.earlhumdev.2006.05.002

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16:15

Ms Sara Arkell, University of Bristol The effects of sleeping on surfaces with different thermal insulation on thermal balance and metabolic rate in term infants in the first month after birth.

16:30

Dr James Ferguson, University of Bristol Selective head cooling is safe, cooling by 10 8C only mildly prolongs coagulation time in the newborn pig

16:45

Dr Giles Kendall, University College London The sensitising effects of inflammation on hypoxic—ischaemic brain injury

Chairman: Professor Andrew Wilkinson, President of the Neonatal Society 17:00

The Tizard Lecture: Hypothermia: from Anecdote to Brain Protection Professor Marianne Thoresen Professor of Neonatal Neuroscience Department of Child Health University of Bristol

18:00

Drinks followed by Dinner at Bristol Zoo

Friday 1st July 2005 Chairman: Dr Anoo Jain 9:00

Dr Zainab Kassim, Kings College London Oxygen saturation and lung volume-effect of sleeping position and postmenstrual age (PMA) in oxygen and non-oxygen dependent prematurely born infants

9:15

Dr Atul Sharma, Kings College London Variations in volume guarantee

9:30

Dr Caroline May, Kings College London Prediction of chronic oxygen dependency

9:45

Dr Robert Carr, Guy’s and St. Thomas’ Hospital Gamma—Delta T-lymphocyte function in newborn infants

10:00

Keynote lecture: Advances in non-invasive fetal medicine Professor Peter Soothill Professor of Fetal Medicine Department of Obstetrics and Gynaecology University of Bristol

11:00

Coffee

Chairman: Dr Andy Lyon, General Secretary of the Neonatal Society 11:30

Dr Peter McEwan, Imperial College London Are ethnic differences in body composition present at birth?

11:45

Dr Tarita Murray-Thomas, Imperial College London Health status at two years in infants born below 29 weeks of gestation-initial experience in developing a pragmatic schedule for longitudinal population based data capture

12:00

Dr Jilly Lloyd, University College London The influence of birthweight for gestational age on neurodevelopmental outcome at 1 year of age in premature infants weighing b 1000 g

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Chairman: Professor Andrew Wilkinson, President of the Neonatal Society 12:15

Keynote lecture: Psychological development of extremely preterm (< 26 weeks) and not so preterm (27—35 weeks) children — The big picture Professor Dieter Wolke University of Bristol (UK) and Jacobs Foundation, Zurich (CH)

13:15

Close of meeting and Lunch

The effects of sleeping on surfaces with different thermal insulation on thermal balance and metabolic rate in term infants in the first month after birth Sara Arkell, Pete Blair, John Henderson, Peter Fleming Institute of Child Life and Health, University of Bristol, BS2 8AE (correspondence to: [email protected]) Background: Exposure to house dust mite antigens in the first year is important in the development of atopic disease. Heavy wrapping is a major risk factor for SIDS, especially for infants over 3 months of age. A new mattress construction [bPurFlokQ] has extremely low thermal resistance, and when used with a washable infant sleeping bag potentially minimises exposure to house dust mite antigen. This bedding arrangement, by reducing the thermal insulation from the mattress, reduces the potential risk of overwrapping in later infancy, though requires careful evaluation of thermal balance in younger infants, who may be at risk of cold stress (1). Objectives: To investigate the thermal balance and metabolic rate in normal term infants, under conditions of thermal neutrality and mild cold stress, whilst sleeping in infant sleeping bags, on the PurFlok mattress and a conventional mattress. Methods: Approval was granted by the Local Research Ethics Committee. Each baby was studied twice (once on each mattress), usually on the same day, at ages 3 weeks, 3 months and 5 months. Full polysomnograms (PSG) were recorded [Alice IV] and infant temperatures (core and peripheral) and environmental temperatures and humidity were recorded every 60 s using digital dataloggers (1). The infants were clothed (vest + babygro), and slept in an infant sleeping bag of 2.5 tog, in an environmental temperature (19—228) calculated to be thermoneutral for infants of 1 month on a conventional mattress (1). Oxygen consumption (VO2) and Carbon dioxide production (VCO2) were recorded every 60 s (Deltatrac) (2). After one sleep cycle the room temperature was lowered to 15—16 8C, and the recording continued until the infant awoke. Sections of recording in Rapid Eye Movement (REM) sleep and in Quiet Sleep (QS) were identified from the PSG, in thermoneutral and cool conditions, and mean values obtained for each temperature, and for VO2 and VCO2. Paired comparisons were made using the Wilcoxon test. We present the results of the 24 paired studies completed on 25 normal term infants at 3 weeks of age.

Results: In thermoneutral conditions, in REM, core and peripheral temperatures and metabolic rates were no different between mattress types, but the core temperature on the PurFlok mattress was slightly higher in QS (36.758 vs 36.598 p = 0.038). When cooled, there was a marked proportional increase in REM sleep. In REM when cooled the core temperature was higher (36.88 vs 36.68 p = 0.001) and the core to peripheral temperature gradient was greater for the PurFlok than for the conventional mattress (4.38 vs 3.58 p = 0.004), despite no difference in metabolic rate. Discussion: In thermoneutral conditions the PurFlok mattress did not significantly affect thermal balance or metabolic rate. Under cool conditions infants preferentially switched into REM sleep, in which thermoregulation is more effective (3), on both mattress types. In cool conditions, the larger core-peripheral temperature gradient on the PurFlok confirms increased heat loss and peripheral vasoconstriction compared with the conventional mattress. The unexpectedly higher core temperature on the PurFlok despite no difference in metabolic rate between mattresses demonstrates the remarkable effectiveness of vasoconstriction to conserve heat in infants of this age. References [1] Wigfield RE, Fleming PJ, Azaz Y, et al. Arch Dis Child 1993;69:181—16. [2] Fleming PJ, Howell T, Clements M, Lucas J. Arch. Dis. Child. 1994;70:187—91. [3] Azaz Y, Fleming PJ, Levine M, et al. Pediat. Res. 1992;32:417—23. Gamma—Delta T-lymphocyte function in newborn infants K. Hamilton1, D.L. Gibbons2, M. Elliott3, A.C. Hayday2, R. Carr1 Departments of Haematology1 Immunobiology2 and Neonatal Paediatrics3, Guy’s and St. Thomas’ Hospital, King’s College London, U.K. ([email protected]) Background: Innate immunity in the newborn is immature, as demonstrated by the inability of neonates to resolve bacteraemia caused by organisms of even low pathogenicity. However, most newborns do not develop bacteraemia during normal colonisation of the gut, which suggests that the newborn gut wall is an effective immunological barrier. Recent evidence from mice suggests that, in the newborn, gamma—delta T-lymphocytes (gy cells), which comprise a

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major component (up to 30%) of gut wall intra-epithelial lymphocytes (IELs), are functionally more mature than alpha—beta T-lymphocytes (ah cells)1. Alpha—beta cells are the predominant (N 95%) T-lymphocyte population in peripheral blood (PB) and lymph nodes, and provide the major component of systemic cell mediated immunity. The functional maturity and role of gy T-cells in human neonates are unknown. The purpose of this study was to compare the functional maturity of PB ah and gy T-cells from preterm neonates, term neonates and adults. Methods: Blood was drawn from 10 preterm neonates (GA 26—31 weeks) within 72 h of birth and again at 4 weeks postnatal age. Cord blood was also obtained from 5 normal term infants, and 8 healthy adults. Whole blood was incubated with PMA and ionomycin to stimulate cytokine production, together with the Golgi channel blockers monensin and brefeldin A to inhibit cytokine

Mean F sd

Adult (n = 8) Preterm: birth (n = 9) Preterm: 4 weeks (n = 8) Term: birth (n = 5)

secretion. Cells were harvested after 16 h, stained for CD3 and TCR-gy t identify lymphocyte subsets, permeabilised and stained for accumulated intracellular IFNg, IL2 and TNFa. The proportion of cells synthesising each cytokine was counted on a MoFlo 6 colour flow cytometer. The study was approved by the Guy’s Hospital Research Ethics Committee. Results: Preterm and term neonates show an almost complete absence of IFNg producing ah T-cells ( p b 0.001, neonate groups v adults), with no functional maturation by 1 month postnatal age. In contrast, the proportion of preterm neonate gy cells producing IFNg was 20 times that of their ah cells ( p = 0.001). Neonate gy cells also actively secrete IL-2 (NS, neonate groups v adults), whereas significantly fewer newborn ah cells secrete IL-2 than in adults ( p b 0.001). The same maturity was not seen for TNFa, which had equally poor production by newborn gy and ah cells.

% Cells IFNg positive

% Cells IL-2 positive

% Cells TNFa positive

ah

gy

ah

gy

ah

gy

20 F 6.9 0.8 F 0.3 1.4 F 0.8 0.9 F 0.7

65 F 21 20 F 11 27 F 19 6.5 F 1.4

31 F 17 6.5 F 4.2 17 F 6.9 6.0 F 5.4

8.3 F 7.6 8.0 F 5.5 12.4 F 7.1 4.6 F 2.4

51 F 9.8 15 F 7.5 29 F 6 15 F 11

45 F 15 8.9 F 6.4 27 F 11 6.5 F 2.9

Discussion: These data demonstrate that, in newborn human infants, peripheral blood gy T-cells have more mature production of the protective TH1 cytokines IFNg and IL-2 than ah T-cells. In newborn mice gy IELs provide protection against intestinal infection before maturation of ah T-cell function.1 We therefore hypothesise that in the newborn human infant gy intra-epithelial lymphocytes may similarly provide the mechanism which prevents bacterial translocation across the gut wall during normal gut colonisation. Reference [1] Ramsburg E, Tigelaar R, Craft J, Hayday A. J Exp Med 2003;198:1403—14. Psychological development of extremely preterm (<26 weeks) and not so preterm (27—35 weeks) children — The big picture Dieter Wolke University of Bristol (UK) and Jacobs Foundation, Zurich (CH) Survival rates of premature births have been increasing with strongest gains made for those babies born at the limits of survival (b 26 weeks gestation). Developmental outcome studies initiated in the 1970s and early 1980s have recently reported outcomes of extremely low birth birthweight (ELBW) or very premature birth into adolescence and early adulthood. Those ELBW who had problems in early childhood are unlikely to outgrow them. Cognitive and academic problems persist into adulthood as do attention, peer and possibly emotional problems and job prospects are somewhat poorer. On the other hand, ELBW are less likely to

engage in antisocial behaviours such as drug abuse, early sex or contact with the police. The lower risk taking behaviour may be because they have less peers to engage in such behaviour. Although they have more handicaps, ELBW do not necessarily view their quality of life as poorer than controls. The new generation of extremely preterm children (EPC, b 26 weeks gestation) who benefited from surfactant and antenatal steroid treatment are currently studied in the EPICure study (1) and the findings at 6 years of age are worrying with only 20% free of some disability and 41% suffering significant learning difficulty. The trends are thus clear: more extremely early gestation survivors are joining the group of preterm births with little indication of improved developmental outcome. EPC boys are highly disadvantaged compared to EPC girls, both regarding mortality, morbidity and developmental outcome. The question is how to improve this situation: a) reduction of premature birth, b) improved neonatal care; or c) improved secondary prevention after discharge? Large randomised intervention studies are mostly lacking so far for all three. The findings from our EPICure study and with larger preterm children so far (e.g. 2,3) let me speculate that different interventions and different timings of interventions are indicated for different gestation groups. It appears that avoiding extremely preterm birth and optimal neonatal care that reduces secondary damage may be the key intervention for those threatening or are born extremely premature. In contrast, post-discharge educational/family interventions in addition may benefit mostly those born slightly preterm or of low birthweight. While the EPC children may have the most severe developmental problems and are the bsexiestQ treatment population for neonatologists, they are also a very small group (well below

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1% of births). In contrast, early educational interventions for the often bforgottenQ 5—6% of larger premature infants with rarer, smaller but often lingering deficits may be an additional interesting and valuable target to improve developmental outcome for all preterm children.

4—12 h for each pig. Each blood sample was taken into citrate, centrifuged and frozen at 80 8C until analysis. Activated Partial Thromboplastin Time (APTT) was measured on each sample, at 39 8C and 29 8C using thermostaticallycontrolled waterbaths.

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Results: APTT was significantly longer when measured at 29 8C (mean (SD) 26.7 (10.6)) than at 39 8C 20.8 (8.3) s ( p b 0.01). Median difference was 5 s, almost 25% of normal APTT.

[1] Marlow N, Wolke D, Bracewell MA, Samara M. Neurologic and developmental disability at 6 years of age after extremely preterm birth. New England Journal of Medicine, 2005;352(1), 9—19. [2] Saigal S, denOuden L, Wolke D, Hoult L, Paneth N, Streiner DL, et al. School-age outcomes in children who were extremely low birth weight from four international population-based cohorts. Pediatrics, 2003;112(4), 943—50. [3] Wolke D, Meyer, R. Cognitive status, language attainment and prereading skills of 6-year-old very preterm children and their peers: the Bavarian Longitudinal Study. Developmental Medicine and Child Neurology, 1999;41(2), 94—109.

Conclusion: With a temperature difference of 10 8C which is the maximum one could expect between brain cortex and core temperature with selective head cooling, there was only a 25% prolongation of coagulation time. This prolongation is not expected to greatly increase the risk of intracranial bleeding. With whole body cooling, the effect would be less. We have not observed brain haemorrhages in studies using SHC for 24 h in piglets (3). The major risks for intracranial bleeding in the term infant remain traumatic delivery and liver damage. References

Selective head cooling is safe, cooling by 10 8C only mildly prolongs coagulation time in the newborn pig James Ferguson1, Frank Britton2, Martin Simmonds1, Andrew Whitelaw1, Marianne Thoresen1 1 Department of Clinical Science, University of Bristol, and 2 Department of Haematology, Southmead Hospital, Bristol The coagulation cascade is a series of enzymatic reactions which are temperature dependent. Several decades ago, severe accidental hypothermia in infants was not uncommon and reports described pulmonary and intracranial haemorrhages (1). Hypothermia is now being evaluated as cerebral protection in infants with hypoxic—ischaemic encephalopathy and 2 studies have shown improved outcome in the cooled group at 18 months follow up. Cooling is either applied as mild total body cooling down to 33.5 8C or as total body cooling to 34.5 8C combined with selective head cooling (SHC) using a cooling cap around the head. There is a possibility that therapeutic hypothermia might increase the risk of intracranial haemorrhage in such infants, particularly if hypoxia has already deranged coagulation. In theory this risk might be further increased if selective head cooling is used as cortical temperatures of 28—29 8C have been documented experimentally (2). Standard clotting assays are performed in routine hospital laboratories at 37 8C. The object of this study was to assess the effect of temperatures likely to occur in cerebral tissue during SHC on coagulation in an experimental model of hypoxic—ischemic encephalopathy. Methods: The study was carried out according to UK Home Office license regulations. 8 newborn pigs less than 24 h old were anaesthetized with 0.8% halothane and were maintained at normothermia (39 8C which is normal for pigs). A median of 4 blood samples was then taken over a period of

[1] Chadd MA, Gray OP. Arch Dis Child 1972;41:819—21. [2] Thoresen M, Simmonds M, Satas S, Tooley J, Silver I. Ped Res 2001;49:594—9. [3] Tooley JR, Satas S, Porter H, Silver IA, Thoresen M. Annal Neurol 2003;53:65—72. Correspondence to: Professor Marianne Thoresen, Child Health, St Michael’s Hospital, Bristol BS2 8EG, UK. Marianne. [email protected]. dWhat has the Human Genome Project done for neonatology?T Professor Mark Gardiner Department of Paediatrics and Child Health, University College London When the Neonatal Society met in Bristol for the first time in the summer of 1965 the era of classical molecular biology was just drawing to a close. Recombinant DNA (1972), DNA sequencing (1977), transgenic mice (1982), the polymerase chain reaction (1983), positional cloning (1986) and The Human Genome Project (1990—2003) all lay in the future. Two years into the post-genomic era the impact of these extraordinary advances on neonatology is negligible and an expert group has just rejected genetic profiling of newborn babies as a public health service. It might however be premature to conclude that genomics has nothing to offer neonatology beyond a deeper understanding of those rare genetic diseases which present in the newborn period. Completion of the 3 billion sequence of the human genome in April 2003 (1) marked the start point of the genomic era in biology and medicine (2). Since then major progress has been made in cataloguing human genetic variation by construction of the HapMap (3), an immensely powerful tool for analysing dcomplexT

614 traits. In parallel sequencing of a range of model organisms is underway or completed including fruit fly, rat, dog, honeybee and chimp. Comparative genomics is providing a detailed molecular understanding in mammals of complex behaviours first investigated in model organisms such as the fly. These advances, together with the advent of technology for high-throughput genotyping will allow the dissection of the influence of nature and nurture on behaviour in the human newborn. Newborn infants are often justifiably accused of a rather limited repertoire of behaviour restricted to sleeping, breathing, feeding and evacuation of bowel and bladder. Sleepless, apnoeic, vomiting and constipated infants constantly remind us of the problems arising when these behaviours go awry. New understanding of their relation to circadian rhythms represents a paradigm for how the molecular and neurochemical control of complex behaviours are being explored. All organisms have evolved under the influence of the earth’s rotation most obviously manifested by the light— dark cycle. In those with a lifespan longer than the solar day this has led to the establishment of endogenous timing systems which synchronise biological functions to the environment by oscillating with a period of approximately (circa-) one day (diem). In mammals, 20,000 neurones in the suprachiasmatic nuclei (SCN) function as the master clock the machinery of which comprises interacting feedback loops orchestrated by a family of genes first identified in the fruit fly. This master oscillator is entrained to the light—dark cycle by specialised retinal photoreceptors. Rare mutations in clock genes (PER2 and CKI7) illustrate the powerful influence of this system on the human sleep—wake cycle (4,5), and studies of chronotypes in adolescence demonstrate the developmental changes which can occur. Most recently the minisleep mutation in fruit flies has revealed an unexpected influence of K+ channels on sleep duration (6) and an unexpected connection between the circadian clock gene network and mammalian energy balance has emerged with the documentation of obesity and metabolic syndrome in clock mutant mice (7). The genetic basis of biological variations in newborn behaviour patterns awaits exploration. In an essay on dThe future of biologyT published in 1927, JBS Haldane predicted that linkage markers could be used on a baby at birth to predict inheritance of characters such as musical ability, mathematical powers, obesity and bad temper. The Human Genome Project has not yet made this prediction a reality. When the society meets in 2045 such developments may still lie in the future, but it may at least be possible to predict which parents can look forward to a good night’s sleep and for which infants sleep truly is the kinsman of death. References [1] http://www.ncbi.nlm.nih.gov/genome/guide/human/. [2] Collins FS, Green ED, Guttmacher AE, Guyer MS. A vision for the future of genomics research. Nature 2003; 422:1—13.

ABSTRACTS [3] http://www.hapmap.org/. [4] Toh KL, et al. An hPer2 phosphorylation site mutation in familial advanced sleep phase syndrome. Science 2001;291:1040—43. [5] Xu Y, et al. Functional consequences of a CKI7 mutation causing familial advanced sleep phase syndrome. Nature 2005;434:640—4. [6] Cirelli C, et al. Reduced sleep in Drosphila Shaker mutants. Nature 2005;434:1087—92. [7] Turek FW, et al. Obesity and metabolic syndrome in circadian Clock mutant mice. Science 2005;308:1043—45. Oxygen saturation and lung volume-effect of sleeping position and postmenstrual age (PMA) in oxygen and non-oxygen dependent prematurely born infants Zainab Kassim, Babita Khetriwal, Harish Rao, Karl Sylvester, Gerrard F. Rafferty, Simon Hannam, Anne Greenough Division of Asthma, Allergy and Lung Biology, Guy’s, King’s and St Thomas’ School of Medicine, King’s College London, Denmark Hill, SE5 9RS, UK Background: Supine sleeping is frequently only started close to NICU discharge in prematurely born infants [1]. Yet, we have shown that at 36 weeks PMA, sleeping position only affects the respiratory status of oxygen dependent infants [2]. Demonstration that the supine position is safe in younger non-oxygen dependent infants might further reassure staff and parents to promote supine sleeping and reduce prone sleeping following discharge. Aim: To test the hypothesis that prone versus supine positioning is associated with superior oxygenation and lung volumes from 32 weeks PMA only in oxygen dependent and not in non-oxygen dependent infants. Patients: Infants born prior to 32 weeks of gestational age. Methods: Infants were studied both supine and prone: each posture maintained for at least one hour. Oxygen saturation (SaO2) was monitored continuously and at the end of each period lung volume was assessed by measurement of functional residual capacity (FRC). This study was approved by the Research Ethics Committee of the King’s Healthcare NHS Trust. Results: Overall, the median SaO2 and FRC were significantly higher in the prone position at 32 (n = 15) and 34 weeks PMA (n = 20). Analysis of the data according to oxygen dependency status, however, demonstrated that the higher lung volumes in the prone position only reached statistical significance at 38 weeks PMA and only in the oxygen dependent group. The median SaO2 levels in the non-oxygen dependent group were similar at 32 and 34 weeks PMA, but tended to be higher in the prone position at 34, 36 and 38 weeks PMA in the oxygen dependent group. Conclusion: These results suggest supine sleeping could be safely instituted at 32 weeks PMA in non-oxygen dependent infants.

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evident when LPS was given within a window of 4—12 h before the onset of HI. No significant sensitisation was observed when LPS was given immediately or 24 h prior to the onset of HI (Fig 1,2).

[1] Bhat RY, Leipala JA, Rafferty GF, Hannam S, Greenough A. Eur J Pediatr 2003;162(6):426—7. [2] Bhat RY, Leipala JA, Singh NR, Rafferty GF, Hannam S, Greenough A. Pediatrics 2003;112:29—32. Corresponding author’s e-mail address: anne.greenough@ kcl. ac.uk The sensitising effects of inflammation on hypoxic—ischaemic brain injury G. Kendall, A. Clements, H. Varley, D. Peebles, G. Raivich Centre for Perinatal Brain Protection and Repair, Department of Obstetrics and Gynaecology, University College London, London WC1E 6HX, Introduction: The fetal brain is protected from the effects of hypoxia—ischaemia (HI) by haemodynamic and metabolic compensatory mechanisms, so that pure HI is a relatively unusual cause of perinatal brain injury. A growing body of epidemiological and experimental animal data suggests that infection may sensitise the developing brain to mild HI,1 reducing the threshold at which HI leads to brain injury. The aims of this study were to investigate the interaction between a bacterial product (endotoxin) mediated inflammation, and hypoxia—ischaemia on neuronal cell death and glial activation in a mouse model of neonatal HI. Methods: Animal procedures were approved by the Home Office, and were carried out according to the UK Animals (Scientific Procedures) Act 1986. Experiments were performed on C57/Bl6 mice at postnatal day 7. An inflammatory reaction was provoked by i.p. injection of 0.3 Ag/g endotoxin (LPS) from E. coli, 055:B5. Mild HI was induced by left-sided carotid occlusion under isoflurane anaesthesia followed by exposure to 8% oxygen for 30 min. These insults were performed independently and in combination. Histological brain injury after HI was assessed at 48 h by measuring infarct volume (expressed as a percentage of the contralateral hemisphere). The effect of LPS was assessed after 12 and 48 h using histology, TUNEL and immunohistochemistry for microglial (aMh2-integrin) and astrocyte (GFAP) activation. Results: Mild HI resulted in minimal histological brain jury with neuronal loss confined to the cortex and hippocampus. LPS alone (0.3 Ag/g) without subsequent HI did not result in any cell death (Nissl, TUNEL). LPS alone did, however, activate microglia in all areas of the forebrain at 12 h following injection ( F 1,25 = 65.6 p b 0.01); this activation was still present at 48 h. LPS alone did not result in astrocyte activation (GFAP) over controls at 12 h, but there was increased GFAP immunoreactivity by 48 h. LPS given 4h before HI resulted in an overall increase in brain injury compared with animals exposed to HI alone ( F 3,19 = 6.37, p b 0.01 n = 10). This sensitising effect was

Discussion: These data support the hypothesis that inflammation sensitises the brain to subsequent HI; further, the magnitude of this interaction depends on the time interval between exposure to LPS and HI. Interestingly, endotoxin alone already resulted in microglial activation within the critical 12 hour period. Activation of the innate immune system by LPS may therefore be an important mediating factor in the synergistic interaction between LPS and HI.2 In comparison, astrocyte activation only occurs relatively late and may be secondary to microglial activation, following infectious and/or hypoxic stimuli. References [1] Peebles DM, Wyatt JS. Synergy between antenatal exposure to infection and intrapartum events in causation of perinatal brain injury at term. BJOG. 2002(Jul); 109(7):737—9.

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[2] Lehnardt S, et al. Activation of innate immunity in the CNS triggers neurodegeneration through a Toll-like receptor 4-dependent pathway. Proc Natl Acad Sci. 2003(Jul 8);100(14):8514—9.

Lloyd J1, Riley K2, Wyatt J2, Peebles D1 1 Department of O and G, 86—96 Chenies Mews, UCL, London, WC1E 6HX, 2Dept of Paediatrics, UCL, London. Email: [email protected]

Young Investigator Prize Lecture

Background: Premature infants are at increased risk of developing cerebral palsy and other neurological problems, such as cognitive and behavioural problems (1). Maternofetal infection/inflammation has been implicated, both as a cause of preterm labour, and perinatal brain injury (2). By contrast, the role of fetal growth restriction in impairing brain development remains unclear, with a poor long-term neurodevelopmental outcome reported in some studies (3) but not in others (4).

Dr Nigel Kennea Wellcome Training Fellow, Hammersmith Hospital, Imperial College, London I have recently completed approaching five years as a research fellow in neonatology with Professor David Edward’s research group at Imperial College. I am currently preparing my PhD thesis for submission. The first eighteen months of research experience were spent working with the group investigating the relationship between intra-uterine infection and inflammation in preterm infants born with brain injury. I gained expertise in generic research methods as well as specific knowledge in magnetic resonance imaging analysis of the newborn brain. At the same time, I began to gain laboratory experience with analysis of total blood for pro-inflammatory cytokines and analysis of fetal membranes for bacteria using a novel in situ hybridization approach. The results revealed an extremely high rate of brain abnormality in extremely preterm infants for which there is no current therapy. This observation led to my successful Wellcome Trust Clinical Training Fellowship application. I proposed to explore the factors affecting neural cell differentiation, and the possibility of autologous cell replacement for newborn brain injury using a novel stem cell approach. My research demonstrated for the first time a method of deriving neurons and oligodendrocytes in vitro from bloodderived (mesenchymal) stem cells in human fetal blood, and the integration and differentiation of such stem cells in the developing murine brain. Not only is this an important first step towards potential autologous stem cell therapy for brain injury, but it also provides a model system which can to used to study the oligodendrocyte development and injury in vitro. This has been presented at international meetings and has been given awards at University, National and International meetings. This work is currently being reviewed for publication in Nature Neuroscience. As a secondary area of research, knowing that the success of stem cells therapy in animal models has been limited by transplant death. I chose to focus on apoptotic pathways in the fetal mesenchymal stem cells. The signalling pathways leading to stem cell death following engraftment are poorly understood. Knowledge of death pathways is necessary in order to prevent graft loss. I established for the first time that human fetal blood stem cells have intact and efficient apoptotic pathways and are sensitive to a variety of cell stresses including growth factor withdrawal and ligation of death receptors. This work has been presented at international meetings and has accepted for publication in Cell Death and Differentiation. The influence of birthweight for gestational age on neurodevelopmental outcome at 1 year of age in premature infants weighing <1000 g

Aims: To investigate the association between intrauterine growth restriction, as well as other known risk factors, and neurodevelopmental outcome in a cohort of premature infants at a single tertiary centre. Methods: 220 premature infants with a birthweight V 1000 g cared for at University College Hospital London from 1995 to 2001, were prospectively followed up at a corrected age of 1 year using a validated neurodevelopmental assessment tool, the Griffiths Mental Development Scales. Birthweight was classified as b2nd, 2nd to 9th and z 10th centile and zscores calculated (the number of standard deviations from the mean birthweight for gestational age) using neonatal birthweight charts derived from a similar population. Histological evidence of placental infarction or chorioamnionitis and ultrasound evidence of brain lesions (cystic periventricular leucomalacia [PVL] or ventricular dilatation N 2SD) were also recorded. A multivariate analysis of risk factors was performed, adjusting for z-score and gestational age. Ethical approval was obtained from joint UCL/UCH ethics committee. Results: 55 of the initial cohort of 291 babies died within the first year; of the remaining 236, 220 had a Griffiths developmental quotient (GQ) recorded (93.2% follow up). On univariate analysis, babies with a birthweight b 2nd centile had a lower mean GQ score than those with a birthweight z 10th centile(82.78 + 18.85 versus 95.31 + 16.54, p b 0.001). The presence of cystic PVL or ventricular dilatation was associated with a lower mean GQ score of 72.50 + 23.13 versus 97.20 + 14.98 ( p b 0.001) and 86.54 + 20.44 versus 98.09 + 14.84 ( p b 0.001) respectively. There was no association between histological chorioamnionitis and GQ score. These findings were confirmed by multivariate analysis with a significant association between lower zscore, gestational age, male gender, the presence of cystic PVL or ventricular dilatation and lower GQ score. In the multivariate model an increase in z-score of 1.0 was associated with an increase in GQ score of 5.6 + 1.48 points; similarly, an increase of 1 week in gestational age increased GQ by 2.1 + 0.71 points. Conclusions: Growth restriction, extreme prematurity and major cranial ultrasound abnormalities have a significant negative association with neurodevelopmental outcome in premature infants at 1 year of corrected age.

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References

was cleared more efficiently from the lungs of wild type mice than the parent wild-type strain Eagan. (n = 4—6, p b 0.05). Surprisingly it was found that SP-D knock-out mice were more efficient than wild-type mice in clearing both Eagan and Eagan 4AHaemophilus strains from mouse lungs, despite the lack of endogenous SP-D (n = 6 p b 0.01). However there was a more pronounced inflammatory reaction in SP-D knock-out mice compared to wild-type mice even after infection with the non-pathogenic Eagan 4A strain at 2.5 h (n = 6 p b 0.01) and 6 h. The recombinant fragment of SP-D promoted phagocytosis of both wild-type and mutant Haemophilus strains.

[1] Hagberg B, Hagberg G, Beckung E, Uvebrant P. Acta Paediatr 2001;90(3):271—7. [2] Dammann O, Leviton A. Pediatr Res 1997;42(1):1—8. [3] Sung IK, Vohr B, Oh W. J Pediatr 1993;123(4):618—24. [4] Gortner L, van Husen M, Thyen U, Gembruch U, Friedrich HJ, Landmann E. Eur J Obstet Gynecol Reprod Biol 2003;110(Suppl 1):S93—7. A recombinant fragment of human SP-D promotes phagocytosis of Haemophilus influenzae strains whose in vivo pathogenicity is inversely related to SP-D binding Rose-Marie Mackay, Mary Deadman ER Moxon and Howard Clark MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, UK OX1 3QU Premature infants have been shown to have low levels of innate immune collectins which could leave them susceptible to infectious disease. Native SP-D binds to LPS on the surface of gram negative bacteria and promotes their phagocytosis and killing. The aims of this study were to test the ability of a recombinant fragment to promote phagocytosis of a model gram negative pathogen, Haemophilus influenzae Eagan and by using mutant strains with well characterised surface LPS structures, characterise SPD—LPS interaction in vitro and assess the relevance of this interaction in vivo. Methods: Wild-type Haemophilus Eagan and mutant Eagan strains with truncated LPS structure were generated by deletion of genes governing LPS biosynthesis in the laboratory of Professor ER Moxon. The binding of human surfactant protein D to purified LPS from wild-type (Eagan) and mutant strains (Eagan 4A, Eagan CA7) with truncated LPS structure and variable exposed core oligosaccharides was compared by ELISA. Binding to the whole wild-type and mutant bacteria was demonstrated by FACS analysis. Wild-type Eagan and strain Eagan 4A with the greatest differences in SP-D binding were evaluated for their pathogenicity in wild type (c57BL/6) and SP-D knock-out mice. Clearance of the organism from the lungs was compared in WT and SP-D knock-out mice, 2.5 h, 6 h and 12 h after intranasal challenge with 107 organisms in 50 Al of PBS by schedule 1 sacrifice and counting colony forming units from plated lung homogenates. Cytokines (MIP-2 and TNF alpha) were assayed in BAL and lung homogenates by ELISA at the same time points. Differential counts of alveolar macrophage and neutrophils after challenge were assessed on cytospins of BAL cells, stained with DiffQuick. Results: There was a direct inverse correlation between SPD binding and the number of branch chain heptoses in the LPS from wild type and mutants strains. In line with our expectations, wild-type Eagan was more pathogenic than the mutant strain with a truncated LPS-Eagan 4A. Eagan 4A

Conclusions: The results confirm that the in vitro interaction between SP-D and LPS on gram negative bacteria correlates with pathogenicity in vivo and that a recombinant fragment of SP-D without the collagenous tail is effective at promoting phagocytosis of this model gram negative organism. Prediction of chronic oxygen dependency Caroline May, Valia Kavvadia, Gabriel Dimitriou and Anne Greenough. Division of Asthma, Allergy and Lung Biology King’s College London Background: Chronic oxygen dependency (COD), bronchopulmonary dysplasia, is a common and important adverse outcome of very premature birth. Affected patients frequently require readmission to hospital and suffer troublesome respiratory symptoms requiring treatment throughout the preschool years. It is therefore essential that safe and effective preventative strategies are identified. Key to optimum use of such strategies is the development of an accurate and simple predictor of high risk infants. Objective: To determine whether a simplified pulmonary score is able to predict COD. Methods: Many bpredictiveQ scores exist, but are complex. As a consequence an existing pulmonary score [1] was simplified such that the score was calculated from the FiO2 multiplied by the level of respiratory support (ventilation 2.5; CPAP 1.5; nasal cannula oxygen 1.0). Infants were scored on days 2 and 7. Patients: 168 VLBW infants entered into a randomised fluid trial [2]. The study was approved by the Research Ethics Committee of King’s College Hospital and parents gave informed written consent. Results: Infants who were oxygen dependent at 28 days had higher scores on days 2 ( p = 0.0007) and day 7 ( p b 0.0001) than the non-oxygen dependent infants. Similarly the day 2 ( p b 0.0001) and day 7 ( p b 0.0001) scores of the infants who had COD at 36 weeks postmenstrual age were higher than the non-COD infants. Construction of ROC curves demonstrated an area under the curve of 0.851 for the score on day 7 in predicting COD.

618

ABSTRACTS

Conclusion: This simplified pulmonary sore may be useful in identifying infants at high risk for developing chronic oxygen dependency. References [1] Madan A, et al. A pulmonary score for assessing the severity of neonatal chronic lung disease. Pediatrics, 2005;115(4):e450—7. [2] Kavvadia V, et al, Randomised trial of fluid restriction in ventilated very low birthweight infants. Arch Dis Child Fetal Neonatal Ed, 2000;83(2):F91—6. Are ethnic differences in body composition present at birth? Peter McEwan1, Sabita Uthaya1, Louise Thomas2, Jimmy Bell2, Neena Modi1 1 Faculty of Medicine, Chelsea and Westminster Campus, Imperial College London, 2 Robert Steiner MR Unit, MRC Clinical Sciences Centre ([email protected]) Introduction and aim: Differences in the distribution of adipose tissue are known to exist between different ethnic groups (1). These contribute to altered susceptibility to several diseases of adult life. We aimed to determine if these differences exist in newborn babies. We utilised data from a larger, ongoing study of body composition in infancy. Methods: This is an observational study. Subjects were full term, appropriate for gestational age, and to date include 20 white European (E) and four black Afro-Caribbean (AC) infants. The study had approval from the local research ethics committee, and parental consent was obtained. Ethnic group was self reported by parents and confirmed by the investigator. Subjects were weighed and measured. Whole body adipose tissue imaging was performed using procedures described at previous meetings of the Neonatal Society (2,3). Babies were scanned in natural sleep within the first week after birth. Images were analysed on commercially available software. Total adipose tissue mass is presented as a percentage of body weight; intraabdominal and subcutaneous adipose tissue is presented as a percentage of total adipose tissue. Data are presented at mean (sd). Comparisons were made using Students t-test (equal variances not assumed). Results: The two study groups were similar in respect of gestational age (E: 39.9(1.4); AC: 39.7(1.6) weeks), scan weight (E: 3.31(0.21); AC 3.08 (0.42) g), head circumference (E: 35.6 (0.9); AC: 34.2 (1.9) cm), and length (E: 51.9 (1.3); AC: 52.3 (1.0) cm). There were significant differences between the two groups in total and intra-abdominal adiposity but not subcutaneous adiposity (table).

Discussion: These data are in keeping with observations in children that show Afro-Caribbeans to have reduced intraabdominal adiposity (4). Differences present at birth suggest that these are not determined by later life-style or diet. We intend to continue this work to see if these preliminary observations are confirmed. References [1] Aloia, et al. Journal of Laboratory and Clinical Medicine American 1996; 64:833—9. [2] Uthaya, et al. Pediatric Research 2005; 57:211—15. [3] Uthaya, et al. Hormone Research 2004; 62:1143—8. [4] Yanovski, et al. American Journal of Clinical Nutrition 1996;64:833—9. Neonatal necrotizing enterocolitis is associated with high resistance flow in the superior mesenteric artery on day 1 of life in preterm infants EM Murdoch1 GCS Smith2 A K Sinha3 ST Shanmugalingam4 ST Kempley3 1 Neonatal Unit, Addenbrookes Hospital, Cambridge, 2 Dept of Obst and Gynec Cambridge University, 3 Neonatal Unit, Royal London Hospital, Whitechapel, London, 4 Neonatal Unit, UCLH NHS Trust Background: Necrotising enterocolitis (NEC) is the most severe gastrointestinal complication associated with preterm birth and has a 25—40% mortality (1). Mucosal injury is thought to be the initiating event that ultimately leads to the development of NEC. Intestinal ischemia may be a key factor in determining such injury. Hypothesis: We hypothesized that infants who subsequently developed NEC would have evidence of increased mesenteric arterial resistance in early neonatal life. Objective: To relate Doppler indices of mesenteric arterial resistance to the risk of developing NEC. Study design and methods Prospective cohort study: Ethical approval was gained and parental consent taken prior to the study. We studied 64 infants admitted for neonatal intensive care. We analyzed the Doppler waveform of the superior mesenteric artery on day 1 of life. Clinical management and diagnosis of NEC were performed blind to the Doppler results. Results were analysed using multivariate logistic regression relating Doppler SMA indices with risk of NEC. Results: When adjusted for gestational age at birth, the following Doppler parameters (expressed as adjusted odds

Mean (standard deviation)

White European (n = 20)

Black Afro-Caribbean (n = 4)

p

% adipose tissue mass % intra-abdominal adipose tissue % subcutaneous adipose tissue

17.7 (2.5) 3.07 (0.5) 91.9 (1.1)

19.7 (1.0) 2.44 (0.4) 92.8 (0.7)

0.02 0.03 0.07

ABSTRACTS ratio [95% CI] of NEC) were significantly predictive of the risk of NEC: diastolic flow (OR for a 1 cm/s change: 0.77, 0.63—0.94, P = 0.009), mean velocity (OR for a 1 cm/s change: 0.89, 0.80—0.99, P = 0.04) and pulsatility index (OR for a 1 unit change 4.03, 1.27—12.8, P = 0.02). The association between NEC and Doppler waveforms indicative of high vascular resistance was independent of a range of other factors and co-morbidities (race, mode of delivery, umbilical arterial catheter, growth restriction, patent ductus arteriosus, respiratory distress syndrome, mechanical ventilation and hypotension). Discussion: This is the first demonstration, to our knowledge, that babies with high resistance patterns of blood flow velocity in the superior mesenteric artery on day 1 of life are at increased risk of developing NEC. This suggests that impaired perfusion of the mesenteric circulation in early neonatal life has a role in the pathophysiology of NEC. We speculate that failure of perfusion may reflect underdevelopment of the vascular tree in fetal life or vaso-constriction in the early neonatal period. References [1] Chandler Semin. Pediatr. Surg. 2000;9:63—72. [2] Bisquera JA. Pediatrics 2002;109:423—8. Address for correspondence: Dr. Edile Murdoch, Dept of Neonatology edile.murdoch@adden brookes.nhs.uk. Box 226 Addenbrookes Foundation Trust and University Hospital, Hills Road, CB2 2QQ. Tel.: 01223 216240. Non-invasive prenatal diagnosis Peter Soothill The era of invasive fetal medicine has achieved massive improvements to patient care. Recently less or non-invasive technologies have been developed and become available. Examples include ultrasound chromosomal risk assessment (reducing the number of diagnostic procedures, Doppler prediction of anaemia, in utero MRI and free fetal DNA in the maternal circulation giving non-invasive access to fetal genetic material. The later is already widely used in the management of red cell iso-immunisation for fetal blood grouping from maternal blood. This technology is also now available for sex associated diseases such as X-linked disease or 21-hydroxylase deficiency. There is also new evidence that the amount of fetal DNA is related to placental damage and so of value in assessing obstetric complications. Finally fetal RNA is also present in maternal blood and that holds the hope of non-invasively assessing transcription. The implications of these recent findings are going to be very considerable. Are we missing something? Detection of infants at risk of congenital syphilis, their treatment and follow-up U Sothinathan1, I. Reeves2, M. Tenant-Flowers2, A. Fowler3, M. Zuckerman3, S. Hannam1

619 1

Department of Child Health, Department of Sexual Health and 3 Department of Virology, King’s College Hospital, London, UK 2

Background: National guidelines state that infants born to mothers with evidence of previous or current treponemal infection at routine antenatal screening should be tested at birth. If treponemal IgM is negative, evidence of declining treponemal IgG titres at three, six and twelve months should be obtained before discharge. Aims: Following two cases of congenital syphilis in this institution we decided to; estimate the seroprevalence of treponemal infection in women booking in the antenatal clinic, assess the adequacy of the antibiotic therapy of pregnant women with suspected syphilis and check the follow-up of their infants. Methods: There is no specific test for syphilis. Treponemal serological assays detect antibody to syphilis, bejel, yaws or pinta. We use an ELISA that detects total treponemal antibody (IgG and IgM). If positive, rapid plasma reagin (RPR) and Treponema Pallidum Particle Agglutination (TPPA) are carried out. All maternal booking bloods from March 2000 to February 2002 were reviewed for positive treponemal serology. Cases of maternal syphilis were then identified by reviewing case notes and adequacy of treatment to prevent vertical transmission of syphilis assessed according to published guidelines.1 All women with positive treponemal serology, detected for the first time on antenatal screening should be treated. Women with primary, secondary or early latent syphilis were defined as being at high risk of vertically transmitting syphilis. All samples obtained from infants born in the study period at this hospital, where dsyphilis serologyT had been requested, were assessed. Those with positive serology had their case notes reviewed. Results: 8517 women were screened. Seventy had positive treponemal serology (seroprevalence = 0.8%, 95% confidence interval 0.7 to 1.1), 43 of whom were diagnosed for the first time during pregnancy as a result of the screening programme. Of these, 23 received inadequate treatment to prevent vertical transmission. A further 5 women, where syphilis had been diagnosed previously, had received inadequate treatment. Five women probably had yaws and 4 were coinfected with HIV. Four women had early latent syphilis, of whom one had been inadequately treated and went on to have the pregnancy terminated. Of the 63 infants born at this institution, 29/63 (46%) were screened at birth, 9/63 (14%) at 3 months, 5/63 (8%) at 6 months and 1/63 (1.5%) at one year. Seven of the 27 infants at low risk of vertical transmission, whose mothers had received suboptimal therapy, were treated at birth. Conclusion: To prevent an increase in the incidence of congenital syphilis, the problem of inadequate screening at birth and incomplete follow-up of at risk infants need to be addressed. Treatment of infants who are at low risk of vertical transmission should also be considered if maternal therapy has been inadequate.

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UK national guidelines on the management of early syphilis. www.bashh.org.

Hypothermia from anecdote to neuroprotective treatment Marianne Thoresen ([email protected]) Professor of Neonatal Neuroscience and Consultant Neonatologist. Clinical Sciences@South Bristol, Child Health, University of Bristol, UK Cooling the body to treat diseases has been described in a variety of situations for 2000 years like after limb trauma, burns, seizures and infection. In our time, intraoperative deep hypothermia (HT) was pioneered in the 1960-ties and allowed cardiac surgery without subsequent brain damage to develop. At the same time, in the newborn, HT after asphyxia was applied by immersing the unresponsive baby in cold water (Dr Westin 1962) or using a cap around the head circulated with cold water (Russia 1982). Also in the 60-ties Bill Silverman reported that premature infants had increased mortality while kept cold in incubators hence cooling was unfortunately abandoned also for term asphyxiated infants. During the 1980—1990-ties significant work was carried out on adult rats showing the protective effect of HT. In particular studies of changing temperature during the hypoxic—ischemic insult showed that mild hypothermia (32—34 8C) was neuroprotective (Ginsburg M 1992). To examine whether hypothermia is neuroprotective starting after the insult, it be brain trauma, stroke, cardiac arrest or neonatal asphyxia is the most interesting clinical question. Furthermore, how cold, for how long and with what time delay can you start cooling and still have a longlasting neuroprotective effect? Also, will hypothermia if effective in rat models work in babies? It was discouraging what happened in experimental stroke research where ~ 300 studies on adult rats showed neuroprotection from different drugs or interventions; 50 of these studies have been tried in humans however only one drug intervention (TPA) has shown to be effective in humans after cerebral stroke if applied within 3 h. No large trial of HT after stroke has been carried out, however mild HT to 35 8C for 9 h in unanaesthetised patients is currently aiming at recruiting 1000 patients (Nordic Stroke HT trial). Hypothermia to 33 8C lasting 48 h after closed brain trauma was only effective in a subgroup of patients (Clifton G 2001), however hypothermia lasting 12 or 24 h after cardiac arrest improved survival and neurological outcome (Berner S and HT group trial NEJM 2002). A recent study applying mild hypothermia after aneurism neurosurgery in patients with subarachnoid haemorrhage showed no benefit of HT (NEJM 2005). From the early nineties research groups in Oslo, London and Auckland investigated the effect of posthypoxic hypothermia in neonatal models, i.e. the 7 day old rat, the near term fetal sheep and the newborn pig. Using these models we were able to show that in the P7 rat 5 h of hypothermia to 32 8C starting immediately after the insult offered both short (Thoresen M 1996) and long term global neuroprotection (Bona E 1998). However in the piglet 3 h of HT (4 8C temperature reduction) only protected mild

ABSTRACTS insults, 24 h of HT however was very neuroprotective (Tooley J 2003) but only if applied during full anesthesia (Thoresen M 2001). It seemed like the stress of being awake and cold counteracted the neuroprotection. Also HT reduced the occurrence of seizures by more than 50% which is not surprising given the membrane stabilizing effect of low temperature. In a piglet study at University College London we found that HT ameliorated secondary energy failure (Thoresen M, Wyatt J 1995) and reduced apoptosis (Edwards D et al. 1995). Crucial in the development of the clinical cooling protocol is the work by Alistair Gunn from Auckland (1997, 1998, 1999) using selective head cooling in fetal sheep. They found that if the start of cooling was delayed after the insult, 50% of the neuroprotection was still present as late as after 6 h. We and others have investigated the mechanism by which HT is neuroprotective and found that HT reduces the release of excitatory amino acids and NO (Thoresen M 1997) as well as Glutamate receptor density (unpublished). Two modes of cooling have been investigated in newborn animal models, total body cooling or a combination of selective head cooling and mild total body cooling. What is intriguing is that in the piglet head cooling study there was a large temperature gradient within the brain, the deep brain temperature was 5 8C lower than core and cortex 8—10 8C colder than core temperature. Despite this, selective head cooling did not offer better cortical protection than total body cooling in this model. In other words we did not find that the very cold cortex was protected more than areas of the brain that were cooled less. A recent study assessing MRI of infants who were body or head cooled (Rutherford M in press Pediatrics 2005) indicates however better cortical protection in the head cooled group. Clinical trials of HT after neonatal encephalopathy have been ongoing since 1999 after the completion of pilot trials to show that it was safe to cool an infant to 33—34 8C for 72 h (Gunn 98, Thoresen 2000, Azzopardi 2001, Shankaran 2001). The first trial to reach completion was that of combined SHC and total body cooling to 34.5 8C which was published in 2005 (Gluckman) by the Cool Cap Study Group. This trial entered severely affected children with a 70% chance of death or severe disability and the results after 18 months follow up showed improved motor outcome excluding the most severely damaged. A published reanalysis revealed a significant overall effect of hypothermia on the primary outcome of death or disability at 18 months (odds ratio 0.52, 95% CI 0.28—0.70, p = 0.04) in the full study population (n = 218) (Gunn 2005). Although not yet published but presented, an American study of whole body cooling to 33.5 8C showed overall improved outcome in the cooled group (Shankaran S 2005). The recent clinical studies are reviewed in Thoresen 2005. In the UK we have recruited 70% of patients in a WBC trial using the same entry criteria as the Cool Cap Trial. With the trial results already published or presented and those soon completed we will be able to conclude whether HT should be introduced as clinical practice after neonatal encephalopathy. Also the prospect of improving the outcome by changing the clinical protocols based on the results from animal data

ABSTRACTS is promising. Experimentally, when cooling was started immediately after the insult hence before the onset of seizures even severe insults were protected. Also the duration of cooling and hence the potential adverse effects may well be shortened if one can start shortly after the insult. Animal experiments have shown that rewarming is stressful, particular for the heart, hence slow rewarming may be beneficial not only for the brain. The issue of timing the insult is of course easy in animal models but often unknown in babies. Also the delay after which HT therapy is not effective may well be different in different species. We know that in the fetal sheep HT still has some effect when started after a 6 hour delay, however in the piglet minimal protection remains with a 3 hour delay. This finding may be explained by the fact that the fetal sheep were cooled for 76 h however the piglets only 24 h. Therefore the dose—duration—delay is a combined entity that only careful clinical studies can sort out. To develop the full potential benefit for HT as neuroprotection this intervention should only be applied using specific protocols where the outcome is monitored. It is fortunate that not only are the key investigators in the experimental trials among those running the big clinical trials but they also collaborate across continents with the common aim of protecting the newborn brain. Acknowledgements: The experimental work was supported by The Wellcome Trust, The Norwegian Research Council, SPARKS and other charities. The cool cap equipment was a loan from Olympic Medical. Sincere thanks to all collaborators on experimental as well as clinical hypothermia projects over the last 13 years. The development of thermoregulation in a harsh environment: a prospective controlled study of the effects of swaddling on infants’ thermal balance in a Mongolian winter Bazarragchaa Tsogt1, Semira Maniseki-Holland2, Jon Pollock1, Pete Blair3 and *Peter Fleming3 University of the West of England1 London School of Hygiene and Tropical Medicine2 Institute of Child Life and Health, University of Bristol BS2 8AE3 (*correspondence to [email protected]). Background: Traditional infant care in Mongolia includes tight swaddling in multiple layers, including partial head covering with hats, during both day and night, throughout the winter. Infants usually sleep under adult bedding, in the same bed as mothers, and swaddling is usually continued until around 7 months of age. Many families live in traditional circular tents called bgerQ, with a single room, and no heating overnight, when outdoor temperatures commonly fall below 40 8C. The high incidence of respiratory infections in infants has been attributed to tight swaddling with restricted chest movements, though the role of thermal stress is not known. Objective: To investigate thermal balance at home of infants in a Mongolian winter, and to compare the effects of swaddling with the effects of an infant sleeping bag of equal thermal resistance.

621 Methods: 1274 healthy term infants were randomly allocated to swaddled or non-swaddled groups (using sleeping bags of equivalent thermal resistance), within 48 h of birth. Digital recordings of infants’ core, peripheral and environmental temperatures at 30 second intervals were made from 40 swaddled and 40 non-swaddled infants over 24 hour periods, at 1 month and 3 months of age, between December and March. Mothers recorded detailed logs of infant activity and wrapping. Results: Temperature recordings suitable for analysis were obtained from 79 infants at both 1 and 3 months. Most infants bedshared with parents and slept under heavy adult bedding as well as the swaddling or sleeping bag. Indoor environmental temperatures during the night commonly fell below 0 8C, and temperatures in the late afternoon (during cooking) commonly rose to above 25 8C, but no episodes of hyper- or hypo-thermia were recorded. Median indoor environmental temperatures were no different for the studies at 1 month and those at 3 months. No differences were identified at either age between environmental, peripheral or core temperatures during either day or night, awake or asleep, for swaddled vs nonswaddled infants. For swaddled and non-swaddled infants during sleep at night at 1 month, median core temperatures (37.0, 36.6) and peripheral temperatures (35.5, 35.2) were significantly higher than those at 3 months (36.2, 36.0 and 29.2, 29.8 respectively) (all p b 0.0001, [Wilcoxon]). Similar differences were noted during daytime sleep periods. Discussion: Despite the harsh environmental conditions, heavy wrapping, bedsharing and head covering, all infants showed effective thermoregulation whether swaddled or in infant sleeping bags. Swaddling offered no thermal advantages over the sleeping bag. The lower core and peripheral temperatures in the older infants reflect the development of the normal fall in body temperature during sleep, particularly at night. These results shed important light on the ability of normal infants to effectively thermoregulate, and to safely achieve normal diurnal falls in core temperature during sleep, despite extreme environmental temperature changes, very high levels of extrinsic insulation, and bedsharing with parents and/or siblings. Variations in volume guarantee Atul Sharma, Anthony D. Milner, Anne Greenough Division of Asthma, Allergy and Lung Biology, Guy’s, King’s and St Thomas’ School of Medicine, King’s College London, Denmark Hill, SE5 9RS, UK Background: During volume guarantee (VG), the inspiratory pressure is automatically modified to achieve the set tidal volume. Preliminary evidence suggests VG may have advantages compared to bconventionalQ ventilation; these include maintenance of blood gases despite use of lower peak pressures and less episodes of desaturation. Preliminary evidence, however, suggests that the method of VG delivery is crucial to its efficacy.

622 Aim: To test the hypothesis that VG delivery would differ according to ventilator type. Methods: An in vitro study was performed and three ventilators (Draeger Babylog 800 SLE 5000, and Stephanie paediatric ventilator) were assessed. Each ventilator was attached to a lung model, which had variable resistance and compliance. Between the lung model and ventilator a pneumotachograph was sited. Flow (integrated to volume) was measured from the pneumotachograph and peak (PIP) and mean airway pressure (MAP) was measured from a side aim on the pneumotachograph. The airway pressure waveform was also recorded. The ventilators were studied in SIPPV mode and a syringe was used to simulate patient breaths.

ABSTRACTS Results: At VG of both 5 and 10 ml, the peak pressure delivered by the ventilators differed significantly (Draegor vs Stephanie p = 0.04; Stephanie vs SLE p = 0.01), the MAP differed (Draeger vs Stephanie p = 0.001); Stephanie vs SLE p = 0.04) and the inspiratory time also differed (Stephanie vs SLE p = 0.01; Draeger vs SLE p = 0.01). These differences resulted from markedly different airway pressure waveforms delivered by the different ventilator types. Conclusion: Before embarking on randomised studies to assess the long term outcome of VG, it is essential to determine which VG mode is most efficacious. Corresponding author’s e-mail address: anne.greenough@ kcl.ac.uk.