Resuscitation of asphyxiated newborn infants with room air or oxygen: an international controlled trial: the Resair 2 study

OBJECTIVE

Birth asphyxia represents a serious problem worldwide, resulting in approximately 1 million deaths and an equal number of serious sequelae annually. It is therefore important to develop new and better ways to treat asphyxia. Resuscitation after birth asphyxia traditionally has been carried out with 100% oxygen, and most guidelines and textbooks recommend this; however, the scientific background for this has never been established. On the contrary, theoretic considerations indicate that resuscitation with high oxygen concentrations could have detrimental effects. We have performed a series of animal studies as well as one pilot study indicating that resuscitation can be performed with room air just as efficiently as with 100% oxygen. To test this more thoroughly, we organized a multicenter study and hypothesized that room air is superior to 100% oxygen when asphyxiated newborn infants are resuscitated.

METHODOLOGY

In a prospective, international, controlled multicenter study including 11 centers from six countries, asphyxiated newborn infants with birth weight >999 g were allocated to resuscitation with either room air or 100% oxygen. The study was not blinded, and the patients were allocated to one of the two treatment groups according to date of birth. Those born on even dates were resuscitated with room air and those born on odd dates with 100% oxygen. Informed consent was not obtained until after the initial resuscitation, an arrangement in agreement with the new proposal of the US Food and Drug Administration's rules governing investigational drugs and medical devices to permit clinical research on emergency care without the consent of subjects. The protocol was approved by the ethical committees at each participating center. Entry criterion was apnea or gasping with heart rate <80 beats per minute at birth necessitating resuscitation. Exclusion criteria were birth weight <1000 g, lethal anomalies, hydrops, cyanotic congenital heart defects, and stillbirths. Primary outcome measures were death within 1 week and/or presence of hypoxic-ischemic encephalopathy, grade II or III, according to a modification of Sarnat and Sarnat. Secondary outcome measures were Apgar score at 5 minutes, heart rate at 90 seconds, time to first breath, time to first cry, duration of resuscitation, arterial blood gases and acid base status at 10 and 30 minutes of age, and abnormal neurologic examination at 4 weeks. The existing routines for resuscitation in each participating unit were followed, and the ventilation techniques described by the American Heart Association were used as guidelines aiming at a frequency of manual ventilation of 40 to 60 breaths per minute.

RESULTS

Forms for 703 enrolled infants from 11 centers were received by the steering committee. All 94 patients from one of the centers were excluded because of violation of the inclusion criteria in 86 of these. Therefore, the final number of infants enrolled in the study was 609 (from 10 centers), with 288 in the room air group and 321 in the oxygen group. Median (5 to 95 percentile) gestational ages were 38 (32.0 to 42.0) and 38 (31.1 to 41.5) weeks (NS), and birth weights were 2600 (1320 to 4078) g and 2560 (1303 to 3900) g (NS) in the room air and oxygen groups, respectively. There were 46% girls in the room air and 41% in the oxygen group (NS). Mortality in the first 7 days of life was 12.2% and 15.0% in the room air and oxygen groups, respectively; adjusted odds ratio (OR) = 0.82 with 95% confidence intervals (CI) = 0.50-1.35. Neonatal mortality was 13.9% and 19.0%; adjusted OR = 0. 72 with 95% CI = 0.45-1.15. Death within 7 days of life and/or moderate or severe hypoxic-ischemic encephalopathy (primary outcome measure) was seen in 21.2% in the room air group and in 23.7% in the oxygen group; OR = 0.94 with 95% CI = 0.63-1.40. (ABSTRACT TRUNCATED)

Similar effects on infants of n-3 and n-6 fatty acids supplementation to pregnant and lactating women

OBJECTIVE

There have been indications that high intake of n-3 long-chain polyunsaturated fatty acids (PUFAs) during pregnancy may increase birth weight and gestational length. In addition, n-3 long-chain PUFAs may be important for the neurobiological development of the infants. High levels of docosahexaenoic acid (DHA, 22:6 n-3) are found in the gray matter of the cerebral cortex and in the retina, and it seems as if the availability of long-chain PUFAs may be limiting cerebral development. The fetus and the newborn are dependent on a high supply from their mothers, either via the placenta or via breast milk. We supplemented pregnant and lactating women with n-3 or n-6 long-chain PUFAs to evaluate the effect on birth weight, gestational length, and infant development.

DESIGN

We performed a double-blind, randomized study recruiting 590 pregnant, healthy, nulli- or primiparous women (19-35 years old) in weeks 17 to 19 of pregnancy. The women were provided 10 mL of either cod liver oil or corn oil daily until 3 months after delivery.

MAIN OUTCOME MEASURES

Primary outcomes were gestational length and birth weight. Electroencephalography (EEG) was done on the second day of life and at 3 months of age. Novelty preference (Fagan test) was used as an indicator of cognitive function at 6 and 9 months of age. The fatty acid pattern in umbilical plasma phospholipids and in breast milk was measured, and dietary assessments were performed, both on the mothers during pregnancy and on the infants at 3 months of age. The growth of the infants was followed up to 1 year of age.

RESULTS

Three hundred forty-one mothers took part in the study until delivery. There were no significant differences in maternal body mass index before pregnancy and at birth, or parity between the 2 groups. Smoking habits and parental education were also similar in the 2 groups. The mean age of the mothers receiving cod liver oil was, by chance, 1 year higher than the age of the mothers receiving corn oil (28.6 [3.4] vs 27.6 [3.2] years). The maternal dietary intake in the 2 groups receiving cod liver oil or corn oil was similar, except for the supplementation. There were no differences in gestational length or birth weight between the cod liver oil group and the corn oil group (279.6 [9.2] vs 279.2 [9.3] days; 3609 [493] vs 3618 [527] g, respectively). Birth length, head circumference, and placental weight were also similar in the 2 groups. The concentrations of the n-3 fatty acids eicosapentaenoic acid (20:5 n-3), docosapentaenoic acid (22:5 n-3), and DHA in umbilical plasma phospholipids were higher in the cod liver oil group compared with the corn oil group (10.8 [7.6] vs 2.5 [1.8] microg/mL, 5.0 [2.6] vs 2.9 [1.3] microg/mL, 55.8 [20.6] vs 45.3 [12.8] microg/mL, respectively). Neonates with high concentration of DHA in umbilical plasma phospholipids (upper quartile) had longer gestational length than neonates with low concentration (lower quartile; 282.5 [8.5] vs 275.4 [9.3] days). No differences in EEG scores or Fagan scores were found, but neonates with mature EEG (N = 70) had a higher concentration of DHA in umbilical plasma phospholipids than neonates with immature EEG (N = 51) on the second day of life. Dietary information from 251 infants at 3 months of age was collected and 85% of these infants were exclusively breastfed, in addition to 12% who were partly breastfed. The breast milk of mothers supplemented with cod liver oil contained more n-3 long-chain PUFAs and less n-6 long-chain PUFAs than breast milk of mothers supplemented with corn oil. There were no significant differences in infant growth during the first year of life between the 2 groups.

CONCLUSIONS

This study shows neither harmful nor beneficial effects of maternal supplementation of long-chain n-3 PUFAs regarding pregnancy outcome, cognitive development, or growth, as compared with supplementation with n-6 fatty acids. However, it confirms that DHA concentration may be related to gestational length and cerebral maturation of the newborn.

International Guidelines for Neonatal Resuscitation: An excerpt from the Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: International Consensus on Science. Contributors and Reviewers for the Neonatal Resuscitation Guidelines

The International Guidelines 2000 Conference on Cardiopulmonary Resuscitation (CPR) and Emergency Cardiac Care (ECC) formulated new evidenced-based recommendations for neonatal resuscitation. These guidelines comprehensively update the last recommendations, published in 1992 after the Fifth National Conference on CPR and ECC. As a result of the evidence evaluation process, significant changes occurred in the recommended management routines for: * Meconium-stained amniotic fluid: If the newly born infant has absent or depressed respirations, heart rate <100 beats per minute (bpm), or poor muscle tone, direct tracheal suctioning should be performed to remove meconium from the airway. * Preventing heat loss: Hyperthermia should be avoided. * Oxygenation and ventilation: 100% oxygen is recommended for assisted ventilation; however, if supplemental oxygen is unavailable, positive-pressure ventilation should be initiated with room air. The laryngeal mask airway may serve as an effective alternative for establishing an airway if bag-mask ventilation is ineffective or attempts at intubation have failed. Exhaled CO(2) detection can be useful in the secondary confirmation of endotracheal intubation. * Chest compressions: Compressions should be administered if the heart rate is absent or remains <60 bpm despite adequate assisted ventilation for 30 seconds. The 2-thumb, encircling-hands method of chest compression is preferred, with a depth of compression one third the anterior-posterior diameter of the chest and sufficient to generate a palpable pulse. * Medications, volume expansion, and vascular access: Epinephrine in a dose of 0.01-0.03 mg/kg (0.1-0.3 mL/kg of 1:10,000 solution) should be administered if the heart rate remains <60 bpm after a minimum of 30 seconds of adequate ventilation and chest compressions. Emergency volume expansion may be accomplished with an isotonic crystalloid solution or O-negative red blood cells; albumin-containing solutions are no longer the fluid of choice for initial volume expansion. Intraosseous access can serve as an alternative route for medications/volume expansion if umbilical or other direct venous access is not readily available. * Noninitiation and discontinuation of resuscitation: There are circumstances (relating to gestational age, birth weight, known underlying condition, lack of response to interventions) in which noninitiation or discontinuation of resuscitation in the delivery room may be appropriate.

Risk factors for sudden intrauterine unexplained death: epidemiologic characteristics of singleton cases in Oslo, Norway, 1986-1995

OBJECTIVE

The epidemiologic characteristics of unexplained stillbirths are largely unknown or unreliable. We define sudden intrauterine unexplained death as a death that occurs antepartum and results in a stillbirth for which there is no explanation despite postmortem examinations, and we present risk factors for this type of stillbirth in singleton gestations.

STUDY DESIGN

Singleton antepartum stillbirths (n = 291) and live births (n = 582) in Oslo were included and compared with national data (n = 2025 and n = 575,572, respectively). Explained stillbirths (n = 165) and live births in Oslo served as controls for the cases of sudden intrauterine unexplained death (n = 76) in multiple logistic regression analyses.

RESULTS

One fourth of stillbirths remain unexplained. The risk of sudden intrauterine unexplained death (1/1000) increased with gestational age, high maternal age, high cigarette use, low education, and overweight or obesity. Primiparity and previous stillbirths or spontaneous abortions were not associated with sudden intrauterine unexplained death.

CONCLUSIONS

Risk factors for sudden intrauterine unexplained death are identifiable by basic antenatal care. Adding unexplored stillbirths to the unexplained ones conceals several risk factors and underlines the necessity of a definition that includes thorough postmortem examinations.

Resuscitation of asphyxic newborn infants with room air or 100% oxygen

To test the hypothesis that room air is superior to 100% oxygen when asphyxiated newborns are resuscitated, 84 neonates (birth weight > 999 g) with heart rate < 80 and/or apnea at birth were allocated to be resuscitated with either room air (n = 42) or 100% oxygen (n = 42). Serial, unblinded observations of heart rates at 1, 3, 5, and 10 min and Apgar scores at 1 min revealed no significant differences between the two groups. At 5 min, median (25th and 75th percentile) Apgar scores were higher in the room air than in the oxygen group [8 (7-9) versus 7 (6-8), p = 0.03]. After the initial resuscitation, arterial partial pressure of oxygen, pH, and base excess were comparable in the two groups. Assisted ventilation was necessary for 2.4 (1.5-3.4) min in the room air group and 3.0 (2.0-4.0) min in the oxygen group (p = 0.14). The median time to first breath was 1.5 (1.0-2.0) min in both the room air and oxygen groups (p = 0.59), and the time to first cry was 3.0 (2.0-4.0) min and 3.5 (2.5-5.5) min in the room air and oxygen groups, respectively (p = 0.19). Three neonates in the room air group and four in the oxygen group died in the neonatal period. At 28 d, 72 of the 77 surviving neonates were available for follow-up (36 in each group), and none had any neurologic sequelae.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of tissue injury by oxygen radicals: implications for neonatal disease

A role of the oxygen radical generating system hypoxanthine-xanthine oxidase in hypoxia-reoxygenation injury was proposed 15 years ago. In recent years, however, new understanding of hypoxia-reoxygenation injury has been achieved and the significance of other oxygen radical generating systems has been acknowledged too. The hypothesis that an oxygen radical disease exists in preterm infants has recently been strengthened; an important observation is that preterm infants have lower activities of erythrocyte Cu/Zn superoxide dismutase compared to term babies. New actions of oxygen radicals have also been emphasized, and recently it has been demonstrated that the degree of protein oxidation of the lung of newborn infants is associated with chronic lung injury. The new insight into the interaction of oxygen radicals with other systems as excitatory amino acids and the NO system also increases the possibility to understand and hence prevent oxygen radical injury in the preterm infant as well as in adults exposed to an increased load of oxygen radicals.

Oxygen toxicity in the neonatal period

Oxygen is toxic because it produces oxygen radicals. One important oxygen radical generating system is hypoxanthine-xanthine oxidase. Hypoxic newborn babies who have elevated concentrations of hypoxanthine in tissues and body fluids and simultaneously are treated with supplementary oxygen, may therefore produce oxygen radicals in excess overwhelming the body's natural defence systems against free radicals. Further, the capacity of many of these defence systems are probably reduced in the preterm baby. A series of conditions in neonates may, at least partly, be caused by oxygen radicals, e.g. bronchopulmonary dysplasia, retinopathy of prematurity, necrotising enterocolitis and patent ductus arteriosus. These conditions may be different facets of one disease; the "Oxygen radical disease in neonatology". It is speculated that oxygen radicals play a role in regulating the perinatal circulation. This new insight concerning the role of oxygen radicals may have fundamental consequences for treatment and handling of sick newborn babies.

Hypoxanthine as a measurement of hypoxia

The hypoxanthine concentration in plasma was found to be a sensitive parameter of hypoxia of the fetus and the newborn infant. The plasma level of hypoxanthine in the umbilical cord in 29 newborn infants with normal delivery varied between 0 and 11.0 mumol/liter with a mean of 5.8 mumol/liter, SD 3.0 mumol/liter. Compared with this reference group the hypoxanthine concentration in plasma of the umbilical cord in 10 newborn infants with clinical signs of intrauterine hypoxia during labor was found to be significantly higher, with a range of 11.0-61.5 mumol/liter, with a mean of 25.0 mumol/liter, SD 18.0 mumol/liter. The plasma level of hypoxanthine in two premature babies developing an idiopathic respiratory distress syndrome was monitored. The metabolite was found to be considerably increased, in one of them more than 24 hr after a period of hypoxia necessitating artificial ventilation. The hypoxanthine level in plasma of umbilical arterial blood was followed about 2 hr postpartum in three newborn infants with clinical signs of intrauterine hypoxia. The decrease of the plasma concentration of the metabolite seemed to be with a constant velocity, as it was about 10 mumol/liter/hr in these cases. A new method was used for the determination of hypoxanthine in plasma, based on the principle that PO2 decreased when hypoxanthine is oxidized to uric acid.

Update on oxygen radical disease in neonatology

An increasing number of articles related to free radicals in the newborn period is published. The hypothesis that there exists a socalled 'Oxygen radical disease of neonatology' has not been proven but an increasing body of evidence seems to indicate that free radicals are involved in several disease processes leading to conditions such as chronic lung disease, retinopathy of prematurity, necrotizing enterocolitis and periventricular leukomalacia. There are also accumulating data implying the involvement of reactive oxygen species and oxidative stress in signal transduction and they therefore perhaps affect growth and development. In the last year there have been no new breakthroughs in antioxidant therapy.

SIDS cases have increased levels of interleukin-6 in cerebrospinal fluid

Cerebrospinal fluid (CSF) from 20 infants who died of sudden infant death syndrome (SIDS), 7 cases of infectious death and 5 cases of violent death were examined with respect to concentrations of interleukin-6 (IL-6). The measurements were performed by ELISA. IL-6 levels in SIDS were significantly lower than in infectious death (p < 0.02), but significantly higher than in violent death (p < 0.02). Since IL-6 plays an important role in immune responses and may induce fever, the findings may suggest that immune activation plays a role in SIDS. The presence of cytokines in the central nervous system (CNS) may cause respiratory depression, especially in vulnerable infants.

Hypoxemia and reoxygenation with 21% or 100% oxygen in newborn pigs: changes in blood pressure, base deficit, and hypoxanthine and brain morphology

To study whether room air is as effective as 100% O2 in resuscitation after hypoxia, hypoxemia (PaO2 2.3-4.3 kPa) was induced in newborn pigs (2-5 d old) by ventilation with 8% O2 in nitrogen. When systolic blood pressure had fallen to 20 mm Hg, animals were randomly reoxygenated with either 21% O2 (group 1, n = 9) or 100% O2 (group 2, n = 11) for 20 min followed by 21% O2 in both groups. Controls (group 3, n = 5) were ventilated with 21% O2 throughout the experiment. Base deficit peaked at 31 +/- 5 mmol/L (mean +/- SD) for both hypoxic groups at 5 min of reoxygenation and then normalized over the following 3 h. There were no statistically significant differences between the two groups during reoxygenation concerning blood pressure, heart rate, base deficit, or plasma hypoxanthine. Hypoxanthine peaked at 165 +/- 40 and 143 +/- 42 mumol/L in group 1 and 2 (NS), respectively, and was eliminated monoexponentially in both groups with an initial half-life for excess hypoxanthine of 48 +/- 21 and 51 +/- 27 min (NS), respectively. Blinded pathologic examination of cerebral cortex, cerebellum, and hippocampus after 4 d showed no statistically significant differences with regard to brain damage. We conclude that 21% O2 is as effective as 100% O2 for normalizing blood pressure, heart rate, base deficit, and plasma hypoxanthine after severe neonatal hypoxemia in piglets and that the extent of the hypoxic brain damage is similar in the two groups.

Bronchopulmonary dysplasia and oxidative stress: are we closer to an understanding of the pathogenesis of BPD?

In recent years a body of data has accumulated, linking the development of bronchopulmonary dysplasia (BPD) to increased oxidative stress in the first few days after birth, since high concentrations of metabolites reflecting increased peroxidation products such as pentane, ethane, protein carbonyl, o-tyrosine, allantoin and F2-isoprostanes, as well as low levels of glutathione and sulfhydryl/total protein ratio, also reflecting increased oxidative load, have been found in the premature infants at risk of or developing BPD. Oxidative stress seems to increase lung antioxidants in some experimental models of BPD and hyperoxia affects foetal lung growth. There are similarities between inflammation and hypoxia/reoxygenation, since both activate a number of inflammatory mediators such as cytokines and adhesion molecules, some of which are found in high concentrations in tracheal aspirate fluid of infants developing BPD. Surfactant production and function are also altered by both hyperoxia and reactive oxygen species per se, making the lungs more vulnerable to injury. This new knowledge may result in new and more efficient therapeutic approaches, hopefully leading to the eradication of BPD in the near future.

Plasma hypoxanthine concentrations in pigs. A prognostic aid in hypoxia

Hypoxemia was induced in pigs by artificial ventilation with 7% oxygen. Death occurred after 21--99 min (mean 48 min). The plasma hypoxanthine and base deficit concentrations increased linearly during hypoxemia and were significantly elevated after 5 min compared to initial values. The correlation between hypoxanthine and base deficit was good (p < 0.001, r = 0.68). The rate of increase of plasma hypoxanthine concentration was correlated with survival time and a significant correlation was found between the negative slope of hypoxanthine increased and survival. Death occurred in all animals when the hypoxanthine concentrations exceeded about 125 mumol/l. These findings indicate that the plasma concentration and the rate of increase of hypoxanthine specifically and sensitively reflect tissue hypoxia.

Leptin levels in pregnant women and newborn infants: gender differences and reduction during the neonatal period

OBJECTIVE

Leptin is a highly hydrophilic protein that circulates in plasma as a 16-kDa protein. It is produced in adipose tissue and also recently described to be synthesized by placental tissue. Plasma concentration of leptin is positively correlated to body fat mass, and administration of recombinant leptin to mice indicates that leptin participates in the regulation of food intake and energy expenditure. Leptin may have a role during initiation of human pubertal development. Gender differences have been reported among adults as well as among children, even after correction for body fat content. Little is known about variation in leptin levels during pregnancy or the level or function of leptin in the growing fetus and infants. The aim of the present study was to examine plasma concentration of leptin in pregnant women and their newborn infants during the first 3 months of life, and to relate plasma leptin concentration to body weight and gender during this period.

MATERIALS AND METHODS

Among 609 women recruited to study the effect of very long-chain n-3 fatty acids during pregnancy, 180 women were selected to study leptin as well. The women were all healthy and nulli- or primiparas, and 16% were smokers. The study was randomized and double-blinded, and the participants received either 10 mL of cod liver oil (Peter Moller, avd.av Orkla ASA, Oslo, Norway) daily or the same amount of corn oil. Blood samples were taken from the mothers during pregnancy in weeks 18 and 35, and from the umbilical cord and from 4- and 14-week-old infants. The mothers' body mass index (BMI) at 18 and 35 weeks of pregnancy was calculated by using body weight recorded within 1 week or, if this was missing, by using means from weights at the closest time points before and after the sampling. The infants were weighed and measured at local health care centers. Plasma leptin concentration was measured by radio immunoassay (Linco Research, St Charles, MO) using recombinant 125I-leptin as tracer.

RESULTS

We found no differences between the group receiving cod liver oil and the group receiving corn oil in any of the measured variables; thus, the groups are treated statistically as one. Leptin concentration in maternal plasma increased during pregnancy from 15.5 +/- 9.0 microg/L (n = 175) in week 18 to 17.7 +/- 10.7 microg/L (n = 166) in week 35. Mothers, pregnant with female fetuses (n = 77), had a significant increase in plasma leptin concentration, from 15.5 +/- 8.8 microg/L (n = 83) at 18 weeks to 18.5 +/- 10.9 microg/L (n = 80) at 35 weeks of pregnancy, whereas in mothers pregnant with male fetuses, the increase was insignificant (15.4 +/- 9.3 microg/L (n = 92) to 17.0 +/- 10.5 microg/L (n = 86). BMI increased during the same time period, from 24.2 +/- 3.3 kg/m to 27.8 +/- 3.8 kg/m (n = 174). There was a significant correlation between BMI and plasma leptin concentration at 18 weeks (r = 0.54, n = 169) and at 35 weeks (r = 0.45, n = 160), but we found no change in the relative leptin concentration (plasma leptin concentration/BMI) from week 18 to week 35. We found no significant difference between smokers and nonsmokers in plasma leptin concentration, neither at 18 nor 35 weeks of pregnancy. Gender differences in plasma leptin concentration was present already at birth in umbilical cord plasma (10.8 +/- 9.2 microg/L for girls [n = 65] vs 7.6 +/- 6.6 microg/L for boys [n = 74]). We also observed gender differences in plasma leptin concentration at 4 weeks (3.9 +/- 1.8 microg/L, n = 68 vs 3.2 +/- 1.8 microg/L, n = 71) and 14 weeks of age (4.9 +/- 2.1 microg/L, n = 61 vs 4.1 +/- 3.1 microg/L, n = 73). Plasma leptin levels at 4 and 14 weeks were lower than the level in umbilical cord plasma (n = 101). An increase in plasma leptin concentration was observed from 4 to 14 weeks of age, both for girls (n = 48) and for boys (n = 60). Leptin concentration in umbilical cord plasma correlated with birth weight (r = 0.44, n = 139), and there was significant corre

Presence of ochratoxin A in human milk in relation to dietary intake

Individual and geographical variations in ochratoxin A (OA) levels in human blood and milk samples may be due to differences in dietary habits. The purpose of this study was to examine the relationship between OA contamination of human milk and dietary intake. Human milk samples were collected from 80 Norwegian women. The usual food intake during the last year was recorded using a quantitative food frequency questionnaire. The concentration of OA in the human milk was determined by HPLC (detection limit 10 ng/l). Seventeen (21%) out of 80 human milk samples contained OA in the range 10-182 ng/l. The women with a high dietary intake of liver paste (liverwurst, liver pâté) and cakes (cookies, fruitcakes, chocolate cakes, etc.) were more likely to have OA-contaminated milk. The risk of OA contamination was also increased by the intake of juice (all kinds). In addition, the results indicate that breakfast cereals, processed meat products, and cheese could be important contributors to dietary OA intake. OA contamination of the milk was unrelated to smoking, age, parity, and anthropometric data other than body weight.

Goal directed reaching and postural control in supine position in healthy infants

The present study focussed on the development and interaction of reaching and posture in supine position in young infants. The kinematics of goal directed reaches and the concurrent ground reaction forces of the total body centre of pressure (COP) in cranial-caudal and medial-lateral direction were recorded in twelve healthy fullterm infants at 4 and 6 months of age. From eight infants, data were available at both ages. The results indicated that between 4 and 6 months, postural stability during reaching in supine position increased, as the oscillatory COP displacement in the medial-lateral direction decreased significantly with increasing age. Concurrently, reaching performance improved, which was reflected by a decrease in the number of movement units (MU), the length of the displacement-path of the hand and an increase of the length and duration of the first MU. The kinematic data of the reaching movements and the COP data were correlated at both ages, but the nature of the relation changed. At 4 months of age, the number of MU was related to the number of COP oscillations in the cranial-caudal direction, whereas at 6 months the maximum velocity of the hand movement was related to the maximum velocity of COP displacement in cranial-caudal and medial-lateral direction. This change might point to the development of a more subtle control of postural adjustments during reaching movements in supine position.

Effect of barbiturates on hydroxyl radicals, lipid peroxidation, and hypoxic cell death in human NT2-N neurons

BACKGROUND

Barbiturates have been shown to be neuroprotective in several animal models, but the underlying mechanisms are unknown. In this study, the authors investigated the effect of barbiturates on free radical scavenging and attempted to correlate this with their neuroprotective effects in a model of hypoxic cell death in human NT2-N neurons.

METHODS

Hydroxyl radicals were generated by ascorbic acid and iron and were measured by conversion of salicylate to 2,3-dihydroxybenzoic acid. The effect of barbiturates on lipid peroxidation measured as malondialdehyde and 4-hydroxynon-2-enal was also investigated. Hypoxia studies were then performed on human NT2-N neurons. The cells were exposed to 10 h of hypoxia or combined oxygen and glucose deprivation for 3 or 5 h in the presence of thiopental (50-600 microM), methohexital (50-400 microM), phenobarbital (10-400 microM), or pentobarbital (10-400 microM), and cell death was evaluated after 24 h by lactate dehydrogenase release.

RESULTS

Pentobarbital, phenobarbital, methohexital, and thiopental dose-dependently inhibited formation of 2,3-dihydroxybenzoic acid and iron-stimulated lipid peroxidation. There were significant but moderate differences in antioxidant action between the barbiturates. While phenobarbital (10-400 microM) and pentobarbital (10-50 microM) increased lactate dehydrogenase release after combined oxygen and glucose deprivation, thiopental and methohexital protected the neurons at all tested concentrations. At a higher concentration (400 microM), pentobarbital also significantly protected the neurons. At both 50 and 400 microM, thiopental and methohexital protected the NT2-N neurons significantly better than phenobarbital and pentobarbital.

CONCLUSIONS

Barbiturates differ markedly in their neuroprotective effects against combined oxygen and glucose deprivation in human NT2-N neurons. The variation in neuroprotective effects could only partly be explained by differences in antioxidant action.

Sudden infant death syndrome victims show local immunoglobulin M response in tracheal wall and immunoglobulin A response in duodenal mucosa

Twenty-two sudden infant death syndrome (SIDS) cases and 22 controls were examined immunohistochemically with regard to IgA, IgM, and IgG plasma cells in tracheal wall and duodenal mucosa. Furthermore, the presence of secretory component in tracheal surface and gland epithelium as well as in duodenal crypt and villus epithelium were evaluated. The examined specimens were obtained at autopsies. The control groups consisted of 11 infants who died of noninfectious causes and 11 who died of infections. In the tracheal wall, the SIDS group had higher IgM cell numbers than the control group that died of noninfectious causes (p less than 0.01), whereas the SIDS victims had lower IgA and IgM cell numbers than the infectious control group (p less than 0.01). In the duodenal mucosa, the SIDS group had significantly higher IgA cell numbers than the noninfectious control group (p less than 0.02) but lower IgA cell numbers than the infection group (p less than 0.01). Secretory component was present in the epithelium from all SIDS cases and controls, both in the tracheal wall glands and in the duodenal crypt mucosa. These findings indicate that the mucosal immune system is stimulated in SIDS.

Erythropoietin, protein, and iron supplementation and the prevention of anaemia of prematurity

The effectiveness of recombinant human erythropoietin (r-HuEpo) in raising haemoglobin concentrations in very low birthweight infants was examined in a randomised multicentre study. Twenty nine 'healthy' appropriate for gestational age infants with birth weights 900-1400 g entered the study at 3 weeks of age. All infants received breast milk supplemented with 9 g/l human breast milk protein from 3 to 8 weeks of age. Eighteen mg iron was given daily from week 3 and was doubled if serum iron concentration fell below 16.0 mumol/l. Fourteen infants were randomised to receive 100 U/kg r-HuEpo subcutaneously three times a week from week 3 to week 7; 15 infants served as controls. After one week reticulocyte and haemoglobin concentrations were significantly higher in the r-HuEpo treated group and the haemoglobin values remained significantly higher throughout r-HuEpo treatment and at the concentrations observed in full term infants. No adverse effects were associated with the treatment. In stable very low birthweight infants with optimal iron and protein intakes, moderate dose r-HuEpo can produce significant gains in red cell production that may be clinically useful.

Diving seals, ischemia-reperfusion and oxygen radicals

The cardiovascular adaptations of seals that contribute to their ability to tolerate long periods of diving asphyxial hypoxia result in episodic regional ischemia during diving and abrupt reperfusion upon termination of the dive. These conditions might be expected to result in production of oxygen-derived free radicals and other forms of highly reactive oxygen species. Seal organs vary during dives with respect to the degree and persistence of ischemia. Myocardial perfusion is reduced and intermittent; kidney circulation is vigorously vasoconstricted. Heart and kidney tissues from ringed seals (Phoca hispida) and domestic pigs (Sus scrofa) were compared in reactions to experimental ischemia. Resulting production of hypoxanthine, indicative of ATP degradation, was higher in pig than in seal tissues. Activity of superoxide dismutase (SOD), an oxygen radical scavenger, was higher in seal heart. We suggest that these results indicate enhanced protective cellular mechanisms in seals against the potential hazard of highly reactive oxygen forms. SOD activity was unexpectedly higher in pig kidney.

Adverse effects of nicotine and interleukin-1beta on autoresuscitation after apnea in piglets: implications for sudden infant death syndrome

OBJECTIVES

Maternal cigarette smoking is established as a major dose-dependent risk factor for sudden infant death syndrome (SIDS). Both prenatal and postnatal exposures to constituents of tobacco smoke are associated with SIDS, but no mechanism of death attributable to nicotine has been found. Breastfeeding gives a substantial increase in absorbed nicotine compared with only environmental tobacco smoke when the mother smokes, because the milk:plasma concentration ratio of nicotine is 2.9 in smoking mothers. Furthermore, many SIDS victims have a slight infection and a triggered immune system before their death, thus experiencing a release of cytokines like interleukin-1beta (IL-1beta) that may depress respiration. Because apneas in infancy are associated with SIDS, we have tested the hypothesis that postnatal exposure to tobacco constituents and infections might adversely affect an infant's ability to cope with an apneic episode. This is performed by investigating the acute effects of nicotine and IL-1beta on apnea by laryngeal reflex stimulation and on the subsequent autoresuscitation.

DESIGN

Thirty 1-week-old piglets (+/-1 day) were sedated with azaperone. A tracheal and an arterial catheter were inserted during a short halothane anesthesia. The piglets were allowed a 30-minute stabilization period before baseline values were recorded and they were randomized to 4 pretreatment groups (avoiding siblings in the same group): 1) immediate infusion of 10 pmol IL-1beta intravenously/kg (IL-1beta group; n = 8); 2) slow infusion of 5 microg nicotine intravenously/kg 5 minutes later (NIC group; n = 8); 3) both IL-1beta and NIC combined (NIC + IL-1beta group; n = 6); or 4) placebo by infusion of 1 ml .9% NaCl (CTR group; n = 8). Fifteen minutes later, apnea was induced by insufflation of .1 ml of acidified saline (pH = 2) in the subglottic space 5 times with 5-minute intervals, and variables of respiration, heart rate, blood pressure, and blood gases were recorded.

RESULTS

Stimulation of the laryngeal chemoreflex by insufflation of acidified saline in the subglottic space produced apneas, primarily of central origin. This was followed by a decrease in heart rate, a fall in blood pressure, swallowing, occasional coughs, and finally autoresuscitation with gasping followed by rapid increase in heart rate, rise in blood pressure, and (in the CTR group) an increase of respiratory rate. Piglets pretreated with nicotine had more spontaneous apneas, and repeated spontaneous apneas caused an inability to perform a compensatory increase of the respiratory rate after induced apnea. This resulted in a lower SaO(2) than did CTR at 2 minutes after apnea (data shown as median [interquartile range]: 91% [91-94] vs 97% [94-98]). The pretreatment with IL-1beta caused prolonged apneas in piglets and an inability to hyperventilate causing a postapneic respiratory rate similar to the NIC. When nicotine and IL-1beta were combined, additive adverse effects on respiratory control and autoresuscitation compared with CTR were observed: NIC + IL-1beta had significantly more spontaneous apneas the last 5 minutes before induction of apnea (2 [.3-3] vs 0 [0-0]). Apneas were prolonged (46 seconds [39-51] vs 26 seconds [22-31]) and followed by far more spontaneous apneas the following 5 minutes (6.6 [4.0-7.9] vs.5 [.2- .9]). Instead of normal hyperventilation after apnea, a dramatic decrease in respiratory rate was seen (at 20 seconds: -45% [-28 to -53] vs +29% [+24-+50], and at 60 seconds: -27% [-23 to -32] vs +3% [-2-+6), leading to SaO(2) below 90% 3 minutes after end of apnea: 89% (87-93) versus 97% (95-98). These prolonged adverse effects on ventilation were reflected in lowered PaO(2), elevated PaCO(2) and lowered pH 2 minutes, and even 5 minutes, after induction of apnea.

CONCLUSIONS

Nicotine interferes with normal autoresuscitation after apnea when given in doses within the range of what the child of a smoking mother could receive through environmental t

A new biochemical method for estimation of postmortem time

Hypoxanthine (Hx) is formed by hypoxic degradation of adenosine monophosphate (AMP) and might be elevated due to antemortem hypoxia. However, it also increases after cessation of the life processes. Until now measurements of potassium in corpus vitreous humor have been used by forensic pathologists to determine postmortem time. In this study the influence of postmortem time and temperature on vitreous humor Hx and potassium levels were compared. Repeated sampling of vitreous humor was performed in 87 subjects with known time of death and diagnosis. The bodies were kept at either 5 degrees C, 10 degrees C, 15 degrees C or 23 degrees C. Hx was measured by means of HPLC and potassium by flame photometry. In 19 subjects from whom samples were obtained within 1.5 h after death, the normal level of Hx could be estimated to be 7.6 mumol/l and that of potassium to be 5.8 mmol/l. The spread of the potassium levels measured shortly after death was much greater than for the corresponding Hx levels. In the four temperature groups the Hx level increased 4.2, 5.1, 6.2 and 8.8 mumol/l per h, respectively, whereas the corresponding figures for potassium were 0.17, 0.20, 0.25 and 0.30 mmol/l per h. The vitreous humor concentration of both Hx and potassium increases fairly linearly after death. The slopes are steeper with increasing temperature. Since the scatter of the levels is greater for potassium than for Hx, the latter parameter seems to be better suited for the determination of time of death in cases without antemortem hypoxia, especially during the first 24 h.