Biology of the neonate
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Biology of the neonate · Jan 1991
REM sleep determined using in utero penile tumescence in the human fetus at term.
To assess how REM/NREM periods can be linked to the determination of the REM/NREM sleep and/or awake state, we have investigated the relationship between the REM/NREM periods and penile tumescence in the human fetus. This study was made on 11 male fetuses from 36 to 41 weeks of gestation. Eye movement and penile tumescence were simultaneously examined with an observation window of 60 min, using two separate real-time ultrasound systems. ⋯ In all cases, the total duration of penile tumescence during the REM period against REM duration was greater than the duration of tumescence during the NREM period against NREM duration with statistical significance. This indicates that the fetal penile tumescence is strongly associated with REM period and the REM period containing penile tumescence in the human fetus can be considered equivalent to REM sleep in utero. In addition, the finding that there exists a part of the REM period lacking penile tumescence suggests the possible origin of the awake state, brought about by advances in fetal development at this stage of gestation.
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Biology of the neonate · Jan 1989
Pulsed Doppler measurement of left ventricular output as early predictor of symptomatic patent ductus arteriosus in very preterm infants.
High left ventricular output (LVO) values are associated with symptomatic left-to-right ductal shunting in preterm infants. However, LVO data prior to the occurrence of symptomatic patent ductus arteriosus (SPDA) are lacking. To determine whether serial measurements could predict a SPDA, we measured LVO from day 1 until day 10 with pulsed Doppler echocardiography in 25 preterm infants with birth weights of less than 1,250 g and hematocrits of more than 0.40. ⋯ From day 1 until day 5 their mean LVO values were significantly higher compared to the group without left-to-right ductal shunt and this increase was secondary to higher stroke volume values. An increase in LVO of more than 60 ml/min/kg consistently preceded SPDA by at least 24 h. Serial measurements of LVO using a single-pulsed Doppler approach can be used for early prediction of SPDA.
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Biology of the neonate · Jan 1979
Malonyldialdehyde formation, oxygen consumption, fatty acid composition in newborn platelets stimulated by thrombin.
The release reaction, the formation of malonyldialdehyde (MDA), the pattern of oxygen consumption, and the variation in fatty acid composition after addition of thrombin (1.67 U/ml) have been investigated in newborn platelets, comparing the obtained data with analogous values showed by adult platelets assumed as normal controls. Newborn platelets showed a release reaction 20% lower than that of controls. ⋯ The study of fatty acid composition demonstrated that in newborn platelets at rest, arachidonic acid is significantly in a higher concentration than in controls and that it decreases after stimulation with thrombin. It is concluded that the pathway of prostaglandins is normally stimulated by thrombin in newborn platelets.
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Biology of the neonate · Jan 1978
Comparative StudyPositive end expiratory pressure: effects on lung mechanics of premature lambs.
Pulmonary mechanics were determined at 0, 3, 6, and 10 cm H2O positive and expiratory pressure (PEEP) in premature lambs at a mean gestational age of 134 days. Functional residual capacity increased (p less than 0.005) by 7% (1.6 ml/kg) per cm H2O PEEP. ⋯ The data suggest that PEEP in excess of 3 cm H2O produces undesirable effects on lung mechanics in premature lambs. These results may be important in predicting contraindications and potential complications of positive pressure breathing in the newborn.
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Using the immunoperoxidase method, major changes in the distribution of lysozyme (LZM) were found to occur during fetal development. At 10 weeks of gestation LZM was detected for the first time in the proximal tubules of the kidney. This generally coincides with the reported appearance of LZM in fetal blood and amniotic fluid. ⋯ At about 18--20 weeks, LZM-positive mononuclear cells were detected in other tissues tested, such as liver, spleen and thymus. Paneth cells were found to be specifically stained at about 20 weeks of gestation. The timing of the appearance of LZM in the various tissues is discussed in relation to the functional maturation of each organ and the ontogeny of this enzyme in other species.