Hippocampal circuit dysfunction in the Tc1 mouse model of Down syndrome

Hippocampal pathology is likely to contribute to cognitive disability in Down syndrome, yet the neural network basis of this pathology and its contributions to different facets of cognitive impairment remain unclear. Here we report dysfunctional connectivity between dentate gyrus and CA3 networks in the transchromosomic Tc1 mouse model of Down syndrome, demonstrating that ultrastructural abnormalities and impaired short-term plasticity at dentate gyrus-CA3 excitatory synapses culminate in impaired coding of new spatial information in CA3 and CA1 and disrupted behavior in vivo. These results highlight the vulnerability of dentate gyrus-CA3 networks to aberrant human chromosome 21 gene expression and delineate hippocampal circuit abnormalities likely to contribute to distinct cognitive phenotypes in Down syndrome.

Effective design for a laboratory discard sterilizer

A modification of the direct air displacement system of processing laboratory discard material in an autoclave is described. The method overcomes many of the drawbacks encountered previously with existing laboratory sterilizers and yet provides an effective means of replacing air with steam in difficult laboratory discard loads. Plastic Petri dishes were used as the standard load and plastic boxes as the container. Thermocouple results indicate that the described method gives good steam penetration of the load and allows safe handling by the operator.

Testing a steam-formaldehyde sterilizer for gas penetration efficiency

A test piece is described for monitoring the performance of low-temperature steam-with-formaldehyde sterilizers. Comparative tests have shown it to be more difficult to penetrate than an arterial catheter when exposed to the same sterilizing conditions. It is permanent and simple to use and maintain. The growth or non-growth of bacterial spores, in the convenient form of spore strips, is used to indicate the efficacy of sterilization.