Early human development
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Early human development · May 1998
Free amino acid distribution inside the first trimester human gestational sac.
The trophoblast functions of nutrient transport and protein synthesis generate high concentrations of amino acids in the placenta and in fetal blood during the second half of pregnancy, but little is known about these metabolic processes in embryonic and early fetal periods. The aim of this study is to compare the distribution of amino acids inside the first trimester gestational sac. Free amino acid concentrations were measured in homogenates of placental villi, in samples of coelomic and amniotic fluid, and in the maternal serum from 17 normal pregnancies between 7 and 11 weeks of gestation. ⋯ The amniotic fluid contained lower mean concentration of all amino acids than coelomic fluid and maternal serum. The concentration distribution of individual amino acids in coelomic and amniotic fluid were related indicating a passive transfer through the amniotic membrane. A coelomic-maternal gradient was observed in 19 out of 24 amino acids measured and positive correlations were found between maternal serum and coelomic fluid for concentrations of alpha-aminobutyric acid, tyrosine and histidine, suggesting that these amino acids are only partially retained and/or transferred more rapidly by the early placenta.
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Early human development · Feb 1998
Developmental patterns of heart rate and variability in infants with persistent apnea of infancy.
During periods of regular breathing, heart rate is slower and more variable in healthy (no history of respiratory distress syndrome) prematurely born infants with persistent apnea, relative to full-term control infants of comparable post-conceptional ages. We tested the hypothesis that the cardiovascular differences may be linked to the persistent apnea, rather than premature birth, by assessing heart rate and variability in full-term infants with persistent apnea. ⋯ Healthy prematurely born infants with persistent apnea showed cardiovascular alterations similar to those of full-term infants with apnea; these alterations differed from those observed in very premature infants with histories of respiratory distress. The postnatal development of cardiovascular aberrations in infants with persistent apnea suggests that mechanisms accompanying apneic events may contribute to long-term alterations in autonomic control.
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Early human development · Apr 1997
Assessment of acute pain in preterm infants by evaluation of facial expression and frequency domain analysis of heart rate variability.
In ten preterm infants (postconceptional age 27-35 weeks) facial expression and heart rate variability (HRV) were investigated during three situations: (a) the infant at rest in its crib or incubator, (b) provocation of the withdrawal flexor reflex by application of von Frey's hairs, and (c) lancing and squeezing for blood sampling. Video recordings of facial expressions, mixed at random, were categorised as the baby being either undisturbed, disturbed or in pain and a detailed scoring for each situation was performed. Mean heart rate (HR) was calculated and power spectral analysis was assessed on data from segments of 45-s duration from the three procedures. ⋯ The lancing and squeezing of the heel evoked a facial expression of pain in all infants. The HR increased and a reduction in both total HRV and power in the low frequency band of the HRV spectrum was seen during blood sampling. The differentiation between painful and non-painful procedures was more apparent when principal component analysis of HRV was applied.
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Early human development · Feb 1997
Hemodynamic effects of intravenous morphine infusion in ventilated preterm babies.
the importance of sedation and analgesia of newborn babies in intensive care is only now receiving recognition in many neonatal units. ⋯ a loading dose of morphine over 2 h did not have any significant effect on MABP or cerebral and cardiac hemodynamics. No adverse effects were noted that could be attributed to morphine therapy.
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Early human development · Apr 1994
Comparative StudyIs a low cerebrospinal fluid blood glucose ratio indicative of infection in patients with post haemorrhagic hydrocephalus?
Cerebrospinal fluid glucose and cerebrospinal fluid:blood glucose ratios were compared in seven patients with post haemorrhagic hydrocephalus having lumbar puncture/ventricular tap as a therapeutic measure. A control group of 10 babies was used, without intraventricular haemorrhage, and having lumbar puncture as part of a septic screen. Of 50 separate taps in the patient group, 38% had blood glucose measured and 76% had CSF glucose measured. ⋯ The median cerebrospinal fluid:blood glucose ratio in the patient group was 0.235 (range, 0.07-0.53) and in the control group was 0.709 (range, 0.6-1.4). Hypoglycorrhachia appears to be a normal finding in patients with post haemorrhagic hydrocephalus and does not indicate infection in these infants. Measurement of cerebrospinal fluid:blood glucose ratio is not warranted when cerebrospinal fluid is drained purely as a therapeutic measure in these patients.