Biomedical subjects
Publications and source records attributed to H Daniels.
134 preterm infants were investigated in their ability to coordinate sucking and breathing. Of those infants who did not coordinate, 79% showed immature cardiorespiratory control whereas of those who suck and breathe simultaneously only 12% had poor cardiorespiratory control. This finding suggests that in infants with poor coordination of sucking and breathing an investigation of cardiorespiratory control might be indicated.
Previous Doppler ultrasound studies assessing cerebral blood flow velocities in the anterior cerebral artery (ACA) among healthy term and preterm infants, showed a widespread range for the calculated flow indices. However, only one of these studies accounted for the infant's behavioural state. In the present study a stable pattern of the cerebral blood flow velocity tracings and of the Pulsatility Index (PI) was observed during state 1, whereas marked fluctuations in cerebral blood flow velocity and PI were found during state 4 or active wakefulness. During state 2, minor variations of cerebral blood flow velocity and PI occurred though tended to be less pronounced than during active wakefulness. Thus at the time of Doppler assessment the cerebral blood flow velocity pattern and its variability will be better understood by taking into account the behavioural state of the infant.
In normal twins the brainstem auditory evoked potential (BAEP) was recorded. The inter-individual variation of the I-V peak latency-interval within the twins appears to be of the same order of magnitude as the variation of the I-V peak latencies generally observed in infants. Consequently we conclude that in low-risk twins the inter-individual variation of the I-V peak latencies of the BAEP is maximally 0.4 msec and cannot be ascribed to a difference in postmenstrual age.
To investigate whether disordered immune function, as shown by abnormalities in lymphokine production, is present in alcoholic liver disease, interleukin-1 and interleukin-2 activity were assayed in a group of patients with acute alcoholic hepatitis in the absence of underlying cirrhosis, and a group of patients with inactive alcoholic cirrhosis. Activities of both IL-1 and IL-2 in alcoholic hepatitis were similar to those of normal individuals, although in abstinent patients with alcoholic cirrhosis, IL-1 activity was increased and IL-2 activity decreased. Lymphocyte transformation in response to PHA in patients with alcoholic hepatitis was significantly impaired when compared with normal controls, and addition of exogenous IL-2 did not correct this impaired response over a wide range of concentrations of both PHA and IL-2. These observations suggest the underlying defects in cell mediated immunity in acute alcoholic hepatitis, as assessed by blast transformation, could be fundamentally different from those of alcoholic cirrhosis and could be secondary to the metabolic effects of acetaldehyde or altered redox potentials on the behaviour of proliferating cells.
The supine posture of 15 low-risk preterm infants was studied to establish whether they have a preferred posture and, if so, whether it changes with age. No over-all preferred posture was found. Almost always one posture was adopted most frequently, but often a great variety of other postures were adopted almost as frequently. There was no correlation between postmenstrual age and preferred posture, the number of different postures, or the duration of longest uninterrupted posture.
Nine 5-year-old infant school children, nine children with moderate learning difficulties, and nine children attending a school for the aphasic were selected on the basis of a counting test to judge relative number under three conditions: counting, guidelines, and control. The displays used consisted of two rows of dots and varied in numerosity and configuration. Length consistent displays were judged right by all children in all conditions on all numerosities. Many errors were made in judging length conflict displays. All groups judged better when they were told to count and when guidelines were added to the displays than in the control condition. Counting did not help more than guidelines. Small number displays were judged best in all conditions.
The aim of the present study was to examine whether immaturity of cardiorespiratory control corresponds to a less mature behavioural state pattern and/or to less efficient feeding behaviour. Fifty-four infants were observed and data polygraphically recorded for 6 hours; a feeding session was included. It was found that infants with immature cardiorespiratory control spent more time in REM-sleep, less time in the active awake state, and were more likely to be inefficient feeders. In addition, 100 infants were observed for risk signs of sudden infant death syndrome and their parents were asked to answer a questionnaire on the sleeping and feeding behaviour of their infants. The majority of the infants with immature cardiorespiratory control were described as bad feeders but good sleepers. We conclude that gathering information about sleeping and feeding behaviour is useful when screening for immaturity of cardiorespiratory control.
In a group of 46 fullterm infants, with a history of paroxysmal cardiorespiratory attacks, the anamnestic characteristics of the attacks were found to be heterogeneous. A 48 hours polygraphic recording was carried out in order to detect signs of immature cardiorespiratory control. Thirty seven percent of these infants were classified as having an immature cardiorespiratory control defined as abnormally long apneic episodes of 15 seconds or more, bradycardia or a high percentage (more than 10% of the time) of periodic breathing. In a group of normal control infants, those signs of immature cardiorespiratory control were significantly less frequently observed (8%). From this it is concluded that those symptoms might be considered as indicators of an increased risk for sudden infant death.
Parental telephone calls and visits are analysed during the entire stay of the premature infant in the neonatal special care unit in Leuven, Belgium. It is concluded that the summation of parental visits and telephone calls is a better measure of parental contact than parental visits or parental telephone calls separately. This measure is significantly related to parental profession. It is not significantly related to the distance between the family home and the hospital, to the presence of a car or a telephone at home or to the presence of siblings. Parental contacts remain stable during the entire stay of the baby in the neonatal special care unit.
In 100 bottle-fed preterm infants feeding efficiency was studied by quantifying the volume of milk intake per minute and the number of teat insertions per 10 ml of milk intake. These variables were related to gestational age and to number of weeks of feeding experience. Feeding efficiency was greater in infants above 34 weeks gestational age than in those below this age. There was a significant correlation between feeding efficiency and the duration of feeding experience at most gestational ages between 32 and 37 weeks. A characteristic adducted and flexed arm posture was observed during feeding: it changed along with feeding experience. A neonatal feeding score was devised that allowed the quantification of the early oral feeding behavior. The feeding score correlated well with some aspects of perinatal assessment, with some aspects of the neonatal neurological evaluation and with developmental assessment at 7 months of age. These findings are a stimulus to continue our study into the relationships between feeding behaviour and other aspects of early development, especially of neurological development.
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We derive a simple but surprising connection between the "deterministic epidemic with recovery" and the spatial birth-and-death process, and discuss its implications for the use of nonlinear differential equation models for the spatial spread of epidemics. This paper consists of a manuscript dating back to 1977, which has been widely referred to in the literature but not previously published, and its more recent extension to include recovery/death in the processes considered, with some additional comments. To aid reference, we retain the original title.
Chick embryos were given daily injections of ethanol (approximately 30 mg/day) either chronically from embryonic days 4 to 15 (E4-E15) or E18, or acutely from E15 to E18. Untreated and saline-injected embryos served as controls. Although morphological indicators of developmental age were not different among groups, chronic ethanol reduced weights of several brain regions. Similar to rodent models of prenatal ethanol exposure, chronic ethanol treatment reduced cerebellar Purkinje cell numbers compared to controls. Chronic but not acute ethanol exposure resulted in a significant reduction in choline acetyltransferase activity in the optic tectum (OT) and forebrain (FB) compared with controls. This study demonstrates that the chick embryo is a viable model to investigate the effects of ethanol exposure on CNS development. Unlike the mammalian fetus, the avian embryo is isolated from maternal interactions and may prove more useful in investigating the mechanisms by which ethanol directly influences brain development.