Biomedical subjects

C E Blanco

Publications and source records attributed to C E Blanco.

At least 55 records · Page 3Linked to original sources

PubMed1999

Hyperoxia and local organ blood flow in the developing chick embryo.

1. Hyperoxia can cause local vasoconstriction in adult animal organs as a protective mechanism against hyperoxia-induced toxicity. It is not known at what time during development this vasoconstrictor capacity is present. Therefore, we measured the cardiac output (CO) distribution in different organs during a period of acute hyperoxia (100 % O2) in the developing chick embryo. 2. Fertile eggs were divided into five incubation time groups (10 and 11, 12 and 13, 14 and 15, 16 and 17, and 18 and 19 days of a normal incubation time of 21 days). Eggs were opened at the air cell and a catheter was inserted into a branch of the chorioallantoic vein for injections of 15 microm fluorescent microspheres during normoxia and at the end of 5 min (test group 1; n = 39) or 20 min (test group 2; n = 21) of hyperoxia exposure (100 % O2). The fraction of CO to an organ was calculated as the fluorescence of the organ sample divided by the sum of the fluorescence of all organs. 3. Only in 18- and 19-day-old embryos did hyperoxia cause a decrease in the fractions of CO to the heart and carcass, and an increase in those to the yolk-sac and chorioallantoic membrane. This response was more pronounced after 20 min (test group 2) than after 5 min (test group 1) of hyperoxia with an additional decrease in the fractions of CO to the brain, intestine and liver (test group 2). 4. These data indicate that local mechanisms for hyperoxia-induced vasoconstriction in the heart, brain, liver, intestine and carcass develop late, during the final 15 % of the incubation period, in the developing chick embryo.

Animals↗

PubMed1999

Relationship between mixed venous oxygen saturation and markers of tissue oxygenation in progressive hypoxic hypoxia and in isovolemic anemic hypoxia in 8- to 12-day-old piglets.

OBJECTIVE: To examine the hypothesis that mixed venous oxygen saturation (SvO2) values, which reflect the residual oxygen after tissue oxygen extraction, would be similar during hypoxic and anemic hypoxia. DESIGN: SvO2 values, oxygen delivery, arterial oxygen content, and fractional oxygen extraction were compared, and critical values were determined based on lactate, the lactate/pyruvate ratio, and oxygen consumption during hypoxic and anemic hypoxia. SETTING: Laboratory of physiology at a university hospital. SUBJECTS: Two groups of eight piglets, 8 to 12 days old. INTERVENTIONS: Piglets were anesthetized, tracheotomized, intubated, and ventilated. A thoracotomy was performed and a fiberoptic catheter was placed in the pulmonary artery to monitor SvO2. A transit time ultrasound flow probe was positioned around the ascending aorta to measure aorta flow. Progressive hypoxic hypoxia was induced by decreasing FI(O2) from baseline (0.30-0.75) to 0.21, 0.15, and 0.10. Progressive anemic hypoxia was induced by a repeated isovolemic exchange transfusion with 50 mL of pasteurized plasma. MEASUREMENTS AND MAIN RESULTS: Fifteen or 30 mins after each intervention, samples were taken from the carotid artery for blood gases, hemoglobin, lactate, and pyruvate and from the pulmonary artery for blood gases and hemoglobin. Hemodynamic, arterial oxygen saturation, and SvO2 measurements were made. The calculated oxygen delivery and oxygen consumption decreased in both hypoxic and anemic hypoxia. At the lowest oxygen delivery level of anemic hypoxia, the decrease in SvO2 was less than that in hypoxic hypoxia (-26% vs. -55%). The range of critical values for SvO2 calculated for each individual piglet below which lactate, the lactate/pyruvate ratio, and oxygen consumption rapidly changed from baseline value was significantly lower in hypoxic hypoxia (11% to 24%) than in anemic hypoxia (26% to 48%). Fractional oxygen extraction increased significantly but not with a change as high as in hypoxic hypoxia 0.31 (range, 0.20-0.41) vs. 0.49 (range, 0.41-0.54). CONCLUSIONS: In comparison with hypoxic hypoxia, critical values of SvO2 are higher in anemic hypoxia, indicating that oxygen unloading from blood to tissues is impaired in anemic hypoxia. These characteristics in oxygen transport and capillary hemodynamics should be taken into consideration when SvO2 is used in clinical critical care.

Anemia↗

PubMed1999

Erythrocyte glutathione S transferase as a marker of oxidative stress at birth.

AIMS: To determine the level of oxidative stress and cell damage as a result of exposure to O(2) at birth. METHODS: Using glutathione S transferase (GST) as an indicator of oxidative stress, GST activity in cord blood was compared with that in samples taken three hours after birth. Twenty four prematurely born infants and eight full term infants were studied. To test whether stronger effects occur under less favourable conditions, the neonates were divided in three groups: healthy premature; sick premature; and healthy full term infants. RESULTS: GST activity three hours after birth was significantly decreased compared with that at birth in all three groups tested. There were no significant differences in the magnitude of this effect among the three groups. CONCLUSIONS: These results indicate that a sudden increase in oxygenation exposes the neonate to oxidative stress. Measurement of GST activity might be useful for the evaluation of protective treatment in trials considering antioxidant strategies.

Biomarkers↗

PubMed1999

High-frequency oscillatory ventilation, partial liquid ventilation, or conventional mechanical ventilation in newborn piglets with saline lavage-induced acute lung injury. A comparison of gas-exchange efficacy and lung histomorphology.

It has been reported that, in diseased lungs, either partial liquid ventilation (PLV) or high-frequency oscillatory ventilation (HFOV) can improve oxygenation better and with less lung injury than conventional mechanical ventilation (CMV). This study was intended as a preclinical comparison between the effects of HFOV, PLV and CMV on gas exchange, lung mechanics and histology. Fifteen anesthetized newborn piglets, with respiratory insufficiency due to repeated saline lung lavage, were allocated to either a PLV, HFOV or CMV (n = 5 each) strategy, and treated for 4 h. Within 30 min of commencing therapy, PLV, HFOV, and CMV improved arterial PO2 (Pa,O2), alveoloarterial oxygen gradient (P(A-a),O2), oxygenation index (OI), venous admixture (va), and arterial PCO2 (Pa,CO2). After 4 h, oxygenation parameters (Pa,O2, P(A-a),O2, OI and venous admixture) were significantly better in the HFOV group than in the PLV group; the CMV group showed a higher Pa,O2 and lower OI than the PLV group. Gas exchange at the end of the experiment was not different from baseline in the HFOV and CMV groups. Lung histology and morphometry were performed after perfusion-fixation at endotracheal deflation pressure corresponding to mean airway pressure at the end of the experiment. Lung injury score and mean linear intercept were not different between the three treatment groups. We conclude that in this model, gas exchange improved significantly in all three ventilation strategies. Indices of oxygenation improved less during PLV. The saline lavage-induced acute lung injury model used as in this study, is less stable than previously thought. The final lung injury is not influenced by the ventilation strategy. We speculate that the impaired gas exchange during PLV is an expression of diffusion limitation and ventilation-perfusion mismatch in a recovering lung.

Animals↗

PubMed1998

Induction of antioxidant enzyme activity by hyperoxia (60 % O2) in the developing chick embryo.

1. At premature birth, man and animals are exposed to relatively high oxygen levels, compared with intra-uterine conditions, at a time when their antioxidant enzyme (AOE) system is still immature. Using the chick embryo as a study model, we investigated changes in the AOE system in response to hyperoxia applied at different time points during the incubation period. Relations between hyperoxia and AOE activity were studied in selected organs (brain, heart, liver, intestine and lungs) of developing chick embryos (during the second half of the incubation period). 2. Incubated White Leghorn eggs were divided into four groups: control (n = 100) and three test groups exposed for 48 h to 60 % O2 on day 10 (test group 1, n = 80), day 14 (test group 2, n = 60) and day 18 (test group 3, n = 30). Superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) enzyme activities were measured in homogenates of the brain, heart, liver, intestine and lungs. 3. Exposure to hyperoxia at different time points during incubation resulted in a 2- to 10-fold increase in SOD activity in all organs except the brain. Catalase and GPx enzyme activities were only induced in test group 1, 48 h after initiation of hyperoxia. 4. In the developing chick embryo, hyperoxia can produce a temporary induction of AOE activity, which is dependent on the AOE, organ, incubation time and time point of exposure.

Animals↗

PubMed1998

Hypothermia during or after severe perinatal asphyxia prevents increase in cyclic GMP-related nitric oxide levels in the newborn rat striatum.

The striatum is rich in nitric oxide synthase (NOS). It is present in a dense fiber network and in a few medium-sized non-spiny interneurons. Previous work showed chronic overexpression of NOS in the rat striatum after a severe perinatal asphyctic (SPA) insult. This was prevented by hypothermia. We investigated whether the overexpression of NOS was accompanied by increased NOS activity. As nitric oxide (NO) is a potent activator of the soluble isoform of guanylyl cyclase, we measured striatal 3',5'-cyclic monophosphate (cyclic GMP) synthesis in 10-day-old (P10) rat pups that were subjected to SPA during normothermia or hypothermia during or after the insult. Cyclic GMP levels in striatal tissue from control pups were approximately 25.8 pmol/mg protein and in the SPA group approximately 38.1 pmol/mg protein (p<0.01). Hypothermia, during as well as after insult, prevented this increase of cyclic GMP. Nomega-nitro-L-arginine (L-NAME) (0.1 mM) decreased cyclic GMP levels in control, SPA and hypothermia treated pups to similar low levels (approximately 8% of level without L-NAME). Sodium nitroprusside (SNP) stimulated cyclic GMP showed no differences between the four groups. This indicates that high cyclic GMP levels in the striatum of rats subjected to SPA are caused by increased NOS activity. Hypothermia after an asphyctic insult could be a promising treatment.

Animals↗

PubMed1998

Cardiac output distribution in response to hypoxia in the chick embryo in the second half of the incubation time.

1. The fetus develops cardiovascular adaptations to protect vital organs in situations such as hypoxia and asphyxia. These include bradycardia, increased systemic blood pressure and redistribution of the cardiac output. The extent to which they involve maternal or placenta influences is not known. The objective of the present work was to study the cardiac output distribution in response to hypoxia in the chick embryo, which is independent of the mother. 2. Fertilized eggs were studied at three incubation times (10-13 days, 14-16 days and 17-19 days of a normal incubation time of 21 days). Eggs were placed in a Plexiglass box in which the oxygen concentration could be changed. Eggs were opened at the air cell and a chorioallantoic vein was catheterized. Cardiac output distribution was measured with 15 micron fluorescent microspheres injected during normoxia, during the last minute of a 5 min period of hypoxia and after 5 min of subsequent reoxygenation. 3. Hypoxia caused a redistribution of the cardiac output in favour of heart (+17 to +160 % of baseline) and brain (+21 to +57 % of baseline) at the expense of liver (-3 to -65 % of baseline), yolk-sac (-46 to -77 % of baseline) and carcass (-6 to -33 % of baseline). 4. The magnitude of the changes in cardiac output distribution to the heart, brain, liver and carcass in response to hypoxia increased with advancing incubation time. 5. The data demonstrate the development of a protective redistribution of the cardiac output in response to hypoxia in the chick embryo from day 10 of incubation.

Animals↗

PubMed1998

Click-evoked oto-acoustic emission measurement in preterm infants.

UNLABELLED: Click-evoked oto-acoustic emissions (CEOAE) are acoustic responses produced by the inner ear, reflecting functional auditory integrity. We studied both the success rate of the CEOAE method and the CEOAE presence in preterm infants during their stay at the Neonatal Intensive Care Unit (NICU), by analysis of the results of longitudinal CEOAE measurements in 19 preterm infants. The CEOAE method proved to be feasible in the majority of the population under study; the CEOAE measurement failed in 8% of the total of 226 attempts. Within the range of 30-40 weeks post-conceptional age (PCA) the CEOAE presence increased from about 50% to 80%. These results show the possible clinical application of CEOAE in a NICU for the monitoring of cochlear function during treatment of preterm infants. CONCLUSION: Bedside CEOAE measurement in preterm infants in a NICU is feasible at a PCA as low as 30 weeks.

Feasibility Studies↗

PubMed1998

The effect of hyperoxia on embryonic and organ mass in the developing chick embryo.

It is known that hyperoxia stimulates growth late in incubation when the chick embryo outgrows the O2 diffusion capacity. We wondered whether hyperoxia could have an effect in the early period prior to the stage where metabolism exceeds the oxygen diffusion capacity of the eggshell. For this we studied four groups of chicken eggs: control group (CG; n = 100) and three test groups (TGs) exposed during 48 h to 60% O2 on days 10, 14, and 18. In the CG, embryonic and organ mass (brain, heart, lungs, liver and intestine) were measured from day 10 until day 21 of incubation. In the TGs embryonic and organ mass were obtained from 24 h after the start of hyperoxia exposure until the end of incubation. In all TGs the most striking growth rate acceleration was observed in the liver and intestine, maximum growth rate accelerations were respectively, 19 and 42% in TG1, 43 and 173% in TG2 and 39% and 84 in TG3. In contrast, the brain was little affected by the hyperoxia exposure, the maximum growth rate acceleration was 14% in TG2. The results suggest that also in the middle of the incubation period O2 availability can be a limiting factor for growth, before metabolism exceeds the oxygen diffusion capacity of the eggshell.

Animals↗

PubMed1998

Nasal high frequency ventilation in neonates with moderate respiratory insufficiency.

AIM: To investigate the efficacy of nasal high frequency ventilation (nHFV) in newborn infants with moderate respiratory insufficiency. METHOD: Twenty one preterm and term neonates were treated with nHFV for respiratory insufficiency. Criteria for starting nHFV were: deterioration on nasal CPAP expressed by a median pH of 7.24 and pCO2 of 8.3 kPa, or increasing FIO2. nHFV was delivered using the Infant Star ventilator. Ventilator setting amplitude was 35 cm H2O; mean airway pressure 7 cm H2O; and frequency 10 Hz. RESULTS: pCO2 decreased significantly from 8.3 kPa to 7.2 kPa after nHFV was started. In five patients nHFV was discontinued after a median period of 6 1/2 hours due to CO2 retention and high oxygen need, and endotracheal mechanical ventilation was started. CONCLUSIONS: nHFV can reduce pCO2 in neonates with moderate respiratory insufficiency and, therefore, could be used to decrease the need for endotracheal mechanical ventilation.

Carbon Dioxide↗

PubMed1998

Use of teicoplanin in preterm neonates with staphylococcal late-onset neonatal sepsis.

OBJECTIVE: To study the clinical pharmacology of teicoplanin in babies admitted to a newborn intensive care unit, by monitoring serum levels, efficacy and potential side effects. METHODS: An open, nonrandomized descriptive study was performed in the neonatal intensive and high care unit of the University Hospital Maastricht, The Netherlands. Twenty-three preterm neonates, gestational age ranging from 26 to 32 weeks (median 28.4 weeks), postnatal age from 5 to 47 days, and birth weight from 570 to 1,740 g, presenting with (suspected) late onset septicemia, were studied. Of 21 culture-proven septicemias, 20 were caused by staphylococci. The teicoplanin loading dose was 15 mg/kg i.v., followed by a maintenance dose of 8 mg/kg every 24 h. Intravenous gentamicin was also administered pending blood culture. Serum teicoplanin concentrations were measured by fluorescence polarization immunoassay. Clinical and microbiological cure/failure rates were determined and possible side effects were monitored. RESULTS: The study of individual pharmacokinetics during multiple-dose intravenous infusions was rendered impossible by apparently inaccurate dosing. Peak (30 min after end of the infusion) and trough teicoplanin levels were stable throughout the study and averaged 27.8 (interquartile range 23.7-32.9) and 12.3 (interquartile range 9.1-16.8) mg/l, respectively. The microbiological and clinical cure rates were 90% in gram-positive septicemia. There was no apparent toxicity. CONCLUSIONS: Inaccurate drug administration was a problem in this study, making a multidose pharmacokinetic study impossible. It is possible that inaccurate drug administration and not current dosage guidelines yielded trough levels below 10 mg/l in 57 (32%) of 176 instances. This pharmaceutical aspect clearly warrants further study. However, microbiological and clinical cure rates were high in gram-positive septicemias. No side effects attributable to teicoplanin therapy were encountered.

Anti-Bacterial Agents↗

PubMed1998

The incidence of retinopathy of prematurity and steroid therapy for broncho-pulmonary dysplasia.

To determine whether prolonged dexamethasone therapy, used in the treatment of bronchopulmonary dysplasia (BPD), affects the incidence of retinopathy of prematurity (ROP), premature born infants (Gestational age < 33 weeks) treated or not with dexamethasone for BPD were retrospectively studied over a 5 year period. Although the dexamethasone treated group had a significant lower gestational age and a longer period of total ventilatory support there was no significant difference in incidence of ROP between the groups.

Antioxidants↗

PubMed1997

Carotid blood flow changes with behavioral states in the late gestation llama fetus in utero.

This study tested the hypothesis that in the llama fetus changes in cerebral blood flow are closely associated with changes in cerebral oxidative metabolism such as occur during transitions between electrocortical states. For the first time reported in any species, instantaneous changes in common carotid blood flow, employed as a continuous index of cerebrovascular perfusion, were related to instantaneous changes in electrocortical activity. Three late gestation fetal llamas were surgically prepared under general anesthesia with vascular catheters, a tracheal and amniotic catheter, and with electrodes implanted to monitor the fetal electrocorticogram (ECoG). In addition, Transonic flow probes were placed around a common carotid artery and a femoral artery. At least 4 days after surgery fetal arterial blood, amniotic and tracheal pressures, carotid and femoral blood flows and the fetal ECoG were recorded continuously. Our results suggest a close association between increases in common carotid blood flow and low voltage ECoG in the llama fetus. Close coupling between instantaneous changes in carotid blood flow and electrocortical states together with the lack of an increase in brain blood flow without increased cerebral oxygen extraction during hypoxemia in the llama fetus supports a fall in cerebral oxidative metabolism in this species during hypoxemic episodes.

Animals↗

PubMed1997

Absence of neuronal damage after umbilical cord occlusion of 10, 15, and 20 minutes in midgestation fetal sheep.

OBJECTIVES: Our purpose was to determine whether neuronal damage results after total umbilical cord occlusion of increasing duration in midgestation fetal sheep. STUDY DESIGN: We performed total umbilical cord occlusion during 10 (n = 11), 15 (n = 8), or 20 (n = 4) minutes in chronically instrumented midgestation fetal sheep. Nine fetuses served as sham controls. During the experiment fetal blood pressure (mean arterial pressure) and heart rate were continuously recorded. Fetal blood gas analyses were performed at regular intervals before, during, and after the occlusion. Three days after the occlusion neuronal damage was evaluated histologically in three regions of the fetal brain. RESULTS: Total umbilical cord occlusion resulted in hypotension, bradycardia, severe mixed acidemia, hypoxia, and hypercapnia. All fetuses survived the occlusion. No neuronal damage nor macroscopic intraventricular or germinal matrix hemorrhages were observed in either group. CONCLUSION: Prolonging the duration of total umbilical cord occlusion in midgestation fetal sheep resulted in a progressive increase in the severity of asphyxia, not in neuronal damage.

Animals↗

PubMed1997

Cardiac output distribution in the chick embryo from stage 36 to 45.

OBJECTIVE: The distribution of cardiac output to different organs is well described in the mammalian fetus. Chick embryos are not often used in perinatal cardiovascular research and therefore it is not known whether they can serve as an animal model for this purpose. In this study we documented cardiac output distribution in chick embryos at increasing incubation time. METHODS: Fertilized eggs from day 10 to 19 with an incubation time of 21 days were studied in 3 increasing incubation time groups (10-13, 14-16 and 17-19 days). For the experiment, the egg was placed in a holder in an incubator. The egg was opened at the air cell and a small vein of the chorioallantoic membrane was catheterized. Twenty thousand fluorescent 15 microns microspheres in 0.2 ml were injected. After 5 min, the embryo was sacrificed and the different organs were dissected and digested for microsphere isolation and subsequent fluorescence analysis. RESULTS: The chorioallantoic membrane, which is the placenta equivalent of the chick embryo, received a relatively large fraction of the combined cardiac output: 52.08% (interquartile range [IQR] 12.67%) on days 10-13 and 40.95% (IQR 27.24%) on days 17-19. Relatively small fractions were distributed: to the heart 2.03% (IQR 1.58) on days 10-13 and 3.18% (IQR 1.95) on days 17-19, and to the brain 3.20% (IQR 1.80) on days 10-13 and 5.02% (IQR 3.39) on days 17-19. As incubation time advanced, the fraction of the combined cardiac output to the chorioallantoic membrane and yolk-sac decreased significantly in favor of the heart and brain. CONCLUSION: This distribution shows great similarity to the one found in the mammalian fetus. The chick embryo is an attractive model for perinatal cardiovascular research.

Allantois↗

PubMed1997

alpha-CGRP mRNA levels in motoneurons innervating specific rat muscles.

Along with acetylcholine, motoneurons express several neuromodulatory peptides. The most extensively studied of these peptides is calcitonin gene-related peptide (CGRP). CGRP modulates the biochemical, physiological and metabolic properties of skeletal muscle primarily through activation of membrane receptors. Virtually all motor pool contain motoneurons that are immunoreactive for CGRP. The purpose of this study was to determine the proportions of motoneurons that express alpha-CGRP in motor pools innervating muscles with different motor unit compositions. These include the soleus, extensor digitorum longus, tensor fascia latae and the diaphragm muscles as well as the spinal nucleus of the bulbocavernosus. The spinal nucleus of the bulbocavernosus provides innervation to the bulbocavernosus/levator ani muscle complex and the external anal sphincter muscle. The spinal nucleus of the bulbocavernosus contained the greatest proportion of alpha-CGRP mRNA-positive motoneurons, followed in descending rank order by the tensor fascia latae, the extensor digitorum longus, the soleus and the diaphragm motor pools. In addition, significant differences between motor pools were observed in the mean relative alpha-CGRP mRNA level among those motoneurons expressing alpha-CGRP. The highest mean relative alpha-CGRP mRNA level was observed in soleus and the extensor digitorum longus motor pools; followed in descending rank order by the tensor fascia latae, the diaphragm and the spinal nucleus of the bulbocavernosus. We have previously shown that muscle contractile inactivity increases the number of motoneurons that express alpha-CGRP and in the relative mRNA levels. The results of the present study suggest that the proportion of motoneurons within a motor pool that express alpha-CGRP may be closely related to the contractile activity (i.e. activation history) of the target muscle.

Analysis of Variance↗

PubMed1997

Anabolic-androgenic steroid induced alterations in choline acetyltransferase messenger RNA levels of spinal cord motoneurons in the male rat.

The effect of chronic supraphysiological doses of anabolic-androgenic steroids, such as those illegally used by recreational, amateur and professional athletes to increase muscle mass and strength, on motoneurons has not been established. The choline acetyltransferase activity levels of perineal muscles in the male rat are modulated by plasma testosterone levels. These muscles are innervated by the sexually dimorphic motoneurons of the spinal nucleus of the bulbocavernosus. Since the primary source of choline acetyltransferase in muscle is motoneuronal, testosterone may modulate perineal muscle choline acetyltransferase activity by regulating choline acetyltransferase messenger RNA levels in motoneurons. The purpose of this study was to determine if choline acetyltransferase messenger RNA levels in cervical and lumbar spinal motoneurons are affected by chronic (four weeks) changes of plasma testosterone levels in the adult male rat. Using in situ hybridization, choline acetyltransferase messenger RNA levels were analysed in four motor columns: the spinal nucleus of the bulbocavernosus, the retrodorsal lateral nucleus of the lumbar spinal cord, and the lateral motor columns of the cervical and lumbar spinal cords. Chronic exposure to supraphysiological levels of testosterone (five- to ten-times physiologic levels) significantly increased choline acetyltransferase messenger RNA in all four motor columns. Subsequent to castration, choline acetyltransferase messenger RNA levels decreased in motoneurons of the spinal nucleus of the bulbocavernosus and the retrodorsal lateral nucleus. This observation suggests that the decrease in choline acetyltransferase activity levels of muscles innervated by spinal nucleus of the bulbocavernosus motoneurons may be due to changes in choline acetyltransferase protein levels. Indeed, testosterone replacement therapy of castrated males prevented the decline of choline acetyltransferase messenger RNA levels in motoneurons. The results of this study demonstrate that anabolic-androgenic steroids can affect the levels of specific messenger RNAs in motoneuron populations throughout the spinal cord suggesting that motoneuronal characteristics are modulated by circulating anabolic-androgenic steroid levels regardless of the purported "androgen sensitivity" of the specific neuromuscular system.

Anabolic Agents↗

PubMed1997

The influence of head position and head position change on spontaneous body posture and motility in full-term AGA and SGA newborn infants.

No consensus exists concerning the influence of head position and head position change on body posture and motility. Especially the existence of an asymmetric tonic neck reflex (ATNR) in full-term newborns is an issue of discussion. Three-hour video recordings were made of 15 full-term appropriate for gestational age (AGA) and 15 full-term small for gestational age (SGA) infants between the third and eight postnatal day. During a playback of the video recording head position, head position change and several movement patterns of the four limbs were fed into a computer using an event-detecting program. Furthermore, spontaneous head turnings were selected and body posture just before, immediately at and 1 min after the head turning were sketched. The data were analyzed concerning: (1) influence of head position on symmetry of movement of the four limbs; (2) the existence of an ATNR and ATNR-related patterns. In both AGA and SGA infants all movement patterns except hand-face and hand-mouth contact showed a symmetrical distribution, independent of head position. Furthermore, the occurrence of an ATNR following a spontaneous head turning in both AGA and SGA infants was rare. From our results it may be concluded that the ATNR is rare in full-term AGA and SGA newborns. Furthermore, this study demonstrates that head position is not a major factor influencing quantitative aspects of spontaneous motor behaviour. The results are of clinical importance as they imply that in the examination of the neurological condition of the full-term newborn infant by means of observation of spontaneous posture and motility, head position is not of major importance.

Functional Laterality↗