Correlations of Enzyme Levels at Birth in Stressed Neonates with Short-Term Outcomes.

INTRODUCTION: Multi-organ injury causes leakage of several intracellular enzymes into the circulation. We evaluated the correlation between the serum-leaked intracellular enzyme levels at the beginning of treatment and the outcome in perinatally stressed neonates. MATERIALS AND METHODS: We retrospectively studied neonates whose 1 minute Apgar score was < 7. We collected initial venous blood sample data, including aspartate transaminase (AST), alanine transaminase (ALT), lactate dehydrogenase (LDH), and creatine kinase (CK) levels, and correlated these with patient short-term outcomes. RESULTS: Of 60 neonates, nine patients were treated with therapeutic hypothermia, and 32 needed mechanical ventilation. The therapeutic hypothermia group showed significantly larger base deficit, and higher lactate, AST, ALT, LDH, and CK (all p < 0.01). The duration of mechanical ventilation significantly correlated with AST, ALT, LDH, and CK levels (all p < 0.01). CONCLUSION: Initial enzyme levels are useful for predicting the duration of mechanical ventilation in stressed neonates.

Mitochondrial impairment in the developing brain after hypoxia-ischemia.

The pattern of cell death in the immature brain differs from that seen in the adult CNS. During normal development, more than half of the neurons are removed through apoptosis, and mediators like caspase-3 are highly upregulated. The contribution of apoptotic mechanisms in cell death appears also to be substantial in the developing brain, with a marked activation of downstream caspases and signs of DNA fragmentation. Mitochondria are important regulators of cell death through their role in energy metabolism and calcium homeostasis, and their ability to release apoptogenic proteins and to produce reactive oxygen species. We find that secondary brain injury is preceded by impairment of mitochondrial respiration, signs of membrane permeability transition, intramitochondrial accumulation of calcium, changes in the Bcl-2 family proteins, release of proapoptotic proteins (cytochrome C, apoptosis inducing factor) and downstream activation of caspase-9 and caspase-3 after hypoxia-ischemia. These data support the involvement of mitochondria-related mechanisms in perinatal brain injury.

The Scottish perinatal neuropathology study: clinicopathological correlation in early neonatal deaths.

BACKGROUND: A proportion of neonatal deaths from asphyxia have been shown to be associated with pre-existing brain injury. OBJECTIVES: (a) To compare the epidemiology of infants displaying signs of birth asphyxia with those not showing signs; (b) to examine the neuropathology and determine if possible the timing of brain insult comparing asphyxiated with non-asphyxiated infants; (c) to compare the clinical features of those born with birth asphyxia with and without pre-labour damage. METHODS: Over a two year period, all 22 Scottish delivery units collected clinical details on early neonatal deaths. Requests for post mortem included separate requests for detailed neuropathological examination of the brain. Infants were classified into two groups: birth asphyxia and non-birth asphyxia. Clinicopathological correlation was used to attempt to define the time of brain insult. RESULTS: Detailed clinical data were available on 137 of 174 early neonatal deaths that met the inclusion criteria. Seventy of 88 parents who had agreed to post mortem examination consented to a detailed examination of additional samples from the brain; in 53 of these cases the infant was born in an asphyxiated condition. All asphyxiated and encephalopathic infants, 38% of mature and 52% of preterm infants with features of birth asphyxia but without encephalopathy, and only one of 12 infants without any signs of birth asphyxia showed damage consistent with onset before the start of labour. CONCLUSIONS: In a large proportion of neonatal deaths, brain injury predates the onset of labour. This is more common in infants born in an asphyxiated condition.

Pathophysiology of perinatal brain damage.

Perinatal brain damage in the mature fetus is usually brought about by severe intrauterine asphyxia following an acute reduction of the uterine or umbilical circulation. The areas most heavily affected are the parasagittal region of the cerebral cortex and the basal ganglia. The fetus reacts to a severe lack of oxygen with activation of the sympathetic-adrenergic nervous system and a redistribution of cardiac output in favour of the central organs (brain, heart and adrenals). If the asphyxic insult persists, the fetus is unable to maintain circulatory centralisation, and the cardiac output and extent of cerebral perfusion fall. Owing to the acute reduction in oxygen supply, oxidative phosphorylation in the brain comes to a standstill. The Na(+)/K(+) pump at the cell membrane has no more energy to maintain the ionic gradients. In the absence of a membrane potential, large amounts of calcium ions flow through the voltage-dependent ion channel, down an extreme extra-/intracellular concentration gradient, into the cell. Current research suggests that the excessive increase in levels of intracellular calcium, so-called calcium overload, leads to cell damage through the activation of proteases, lipases and endonucleases. During ischemia, besides the influx of calcium ions into the cells via voltage-dependent calcium channels, more calcium enters the cells through glutamate-regulated ion channels. Glutamate, an excitatory neurotransmitter, is released from presynaptic vesicles during ischemia following anoxic cell depolarisation. The acute lack of cellular energy arising during ischemia induces almost complete inhibition of cerebral protein biosynthesis. Once the ischemic period is over, protein biosynthesis returns to pre-ischemic levels in non-vulnerable regions of the brain, while in more vulnerable areas it remains inhibited. The inhibition of protein synthesis, therefore, appears to be an early indicator of subsequent neuronal cell death. A second wave of neuronal cell damage occurs during the reperfusion phase. This cell damage is thought to be caused by the post-ischemic release of oxygen radicals, synthesis of nitric oxide (NO), inflammatory reactions and an imbalance between the excitatory and inhibitory neurotransmitter systems. Part of the secondary neuronal cell damage may be caused by induction of a kind of cellular suicide programme known as apoptosis. Knowledge of these pathophysiological mechanisms has enabled scientists to develop new therapeutic strategies with successful results in animal experiments. The potential of such therapies is discussed here, particularly the promising effects of i.v. administration of magnesium or post-ischemic induction of cerebral hypothermia.

Role of asphyxia and slow intrauterine growth in morbidity among breech delivered infants.

The outcome of breech delivery was evaluated by a neonatal neurological score and a follow-up examination at 18 months of age. The subjects were 132 children identified by ultrasound to be in breech presentation in the 33rd gestational week. 62 were born in breech presentation, while 70 turned to vertex presentation. During the early neonatal period, a neurological score was obtained based on the results of 29 items concerning posture, muscle tone, reflexes and reactions. Although there was no difference, in neurological score or in general development when the entire breech and vertex groups were compared, the SGA (small-for-gestational age) infants and the infants with low Apgar scores of the breech group had the poorest neurological scores. The contribution of certain maternal and fetal factors to postnatal condition was evaluated by a multiple linear regression analysis. Within the breech group, relationships were found between the neurological score and the variables intrauterine growth, fetal sex, and low Apgar score. A major part (66%) of the variation in neurological score was explained by the combination of these variables. These factors should therefore be taken into consideration when deciding on the mode of delivery in breech presentation.