Prevalence and etiology of false normal aEEG recordings in neonatal hypoxic-ischaemic encephalopathy.

BACKGROUND: Amplitude-integrated electroencephalography (aEEG) is a useful tool to determine the severity of neonatal hypoxic-ischemic encephalopathy (HIE). Our aim was to assess the prevalence and study the origin of false normal aEEG recordings based on 85 aEEG recordings registered before six hours of age. METHODS: Raw EEG recordings were reevaluated retrospectively with Fourier analysis to identify and describe the frequency patterns of the raw EEG signal, in cases with inconsistent aEEG recordings and clinical symptoms. Power spectral density curves, power (P) and median frequency (MF) were determined using the raw EEG. In 7 patients non-depolarizing muscle relaxant (NDMR) exposure was found. The EEG sections were analyzed and compared before and after NDMR administration. RESULTS: The reevaluation found that the aEEG was truly normal in 4 neonates. In 3 neonates, high voltage electrocardiographic (ECG) artifacts were found with flat trace on raw EEG. High frequency component (HFC) was found as a cause of normal appearing aEEG in 10 neonates. HFC disappeared while P and MF decreased significantly upon NDMR administration in each observed case. CONCLUSION: Occurrence of false normal aEEG background pattern is relatively high in neonates with HIE and hypothermia. High frequency EEG artifacts suggestive of shivering were found to be the most common cause of false normal aEEG in hypothermic neonates while high voltage ECG artifacts are less common

Growth and body composition of preterm infants: a longitudinal study from birth to 1 year of age

International audienc

Importance of metallothioneins in the cadmium detoxification process in Daphnia magna

International audienceGood knowledge of the relationship between toxic metals and biological systems, particularly the sub-cellular fraction, could be a suitable early indicator of toxic effects. These effects and the sub-cellular behaviour of cadmium were studied with a widely used species in freshwater toxicity bioassays, Daphnia magna. In spite of this very commonplace usage in ecotoxicological studies, very few data are available on its toxicant metabolism and in particular metal homeostasis. Combining multi-tools analysis, a soluble protein was found: it is heat-stable, rich in sulfhydryl groups (differential pulse polarography), characterised by a molecular mass of approximately 6.5 kDa, with a G-75 chromatographic profile corresponding to the rabbit metallothioneins monomer, with few if any aromatic-containing amino acids, it binds metals (e.g. Cd, Cu), and its concentration increases with Cd exposure. This evidence led us to hypothesise that metallothioneins (MTs) are present in D. magna. Up to 75% of the Cd body burden with Cd exposure is bound to the MTs fraction. The increase in the Cd concentration in the surrounding medium and concomitantly in daphnids induces sub-cellular reorganisation of essential metals such as Cu and Zn. The rate of metals in the soluble cellular fraction and associated with MTs increases with the Cd body burden. Monitoring sub-cellular distribution of metals after exposure in the natural environment could be very useful for ecotoxicological assessment

Neonatal thermoregulation

The human being is a homeotherm. Homeothermy is a result of thermoregulation which includes many physiological processes. Thermoregulation maintains an equilibrium between heat production (thermogenesis) and heat loss (thermolysis). There are three principal modes of heat production: 1. Voluntary muscle activity. 2. Involuntary tonic or rhythmic muscle activity known as "shivering". 3. Non-shivering thermogenesis (NST) essential for newborns. Heat loss occurs in two stages: 1. The flow of heat from the center of the body to its surface. 2. The flow of heat from the body surface to the environment by conduction, convection, radiation or water evaporation. Even in the very small premature baby, we find that metabolic and vasomotor control responses are developed. To protect the newborn from stress resulting from hypo or hyperthermia, one should take into consideration the concept of the neutral temperature range which is also called the "Thermoneutral Zone" in (TNZ) or "Thermal Neutrality". Curves, proposed in 1971 by Hey are essential for keeping newborns in the TNZ