Secretions from placenta, after hypoxia/reoxygenation, can damage developing neurones of brain under experimental conditions.

Some psychiatric diseases in children and young adults are thought to originate from adverse exposures during foetal life, including hypoxia and hypoxia/reoxygenation. The mechanism is not understood. Several authors have emphasised that the placenta is likely to play an important role as the key interface between mother and foetus. Here we have explored whether a first trimester human placenta or model barrier of primary human cytotrophoblasts might secrete factors, in response to hypoxia or hypoxia/reoxygenation, that could damage neurones. We find that the secretions in conditioned media caused an increase of [Ca(2+)]i and mitochondrial free radicals and a decrease of dendritic lengths, branching complexity, spine density and synaptic activity in dissociated neurones from embryonic rat cerebral cortex. There was altered staining of glutamate and GABA receptors. We identify glutamate as an active factor within the conditioned media and demonstrate a specific release of glutamate from the placenta/cytotrophoblast barriers invitro after hypoxia or hypoxia/reoxygenation. Injection of conditioned media into developing brains of P4 rats reduced the numerical density of parvalbumin-containing neurones in cortex, hippocampus and reticular nucleus, reduced immunostaining of glutamate receptors and altered cellular turnover. These results show that the placenta is able to release factors, in response to altered oxygen, that can damage developing neurones under experimental conditions.

The use of trypsin to confirm the presence of macrocreatine kinase on isoenzyme electrophoresis.

BACKGROUND: Macrocreatine kinase (MCK) type 1 is a high molecular weight form of CK that is non-pathological. Identification of MCK is beneficial in preventing unnecessary investigations that may follow a persistently elevated CK of unknown origin. Currently, gel filtration chromatography can be used as a confirmatory technique, but it is laborious, time-consuming and expensive. The aim of this work, carried out as part of a larger investigation into the prevalence of MCK, was to determine whether trypsin can be used as an alternative to confirm the presence of MCK on isoenzyme electrophoresis. METHODS: Five samples found to have bands running in the MCK region on isoenzyme electrophoresis were treated with trypsin. Electrophoresis was carried out using the Helena Biosciences Sas-1 Plus system. These samples were also analysed by the confirmatory technique of gel filtration chromatography. RESULTS: Of the five samples treated with trypsin, three were found to be MCK-positive and two MCK-negative. These results correlated with those obtained by the reference method of gel filtration chromatography. CONCLUSIONS: There appears to be a potential use of trypsin in confirming the presence of MCK following isoenzyme electrophoresis. If these findings were verified, this would provide a less labour-intensive, less time-consuming and more cost-effective confirmatory technique. Further study is required, which needs to be expanded to include a larger number of patients, before this method can be adopted routinely.

Cholinesterase: phenotyping and genotyping.

The plasma enzyme butyrylcholinesterase (BChE) is of clinical interest because of the occurrence of genetic variants with decreased ability to hydrolyse, and therefore inactivate, muscle-relaxant drugs such as suxamethonium. Analysis of BChE involves the determination of both enzyme activity and biochemical phenotypes which are used to determine the risk of so-called 'scoline apnoea'. Problems in analysis arise from both the lack of a universally accepted reference method and the variety of substrates and conditions employed for the determination of activity and phenotypes. Phenotype is determined by the use of specific enzyme inhibitors that produce phenotype-specific patterns of 'inhibitor numbers'. DNA analysis is now possible, and true genotypes can be obtained. The nomenclature in use for cholinesterase studies can cause problems in interpretation and reporting as there is poor understanding of the difference between phenotype and genotype, and terms are often, inappropriately, transposed. Techniques for both biochemical and molecular analysis of the enzyme are discussed.