Hedgehog agonist therapy corrects structural and cognitive deficits in a Down syndrome mouse model

Down syndrome (DS) is among the most frequent genetic causes of intellectual disability, and ameliorating this deficit is a major goal in support of people with trisomy 21. The Ts65Dn mouse recapitulates some major brain structural and behavioral phenotypes of DS, including reduced size and cellularity of the cerebellum and learning deficits associated with the hippocampus. We show that a single treatment of newborn mice with the Sonic hedgehog pathway agonist SAG 1.1 (SAG) results in normal cerebellar morphology in adults. Further, SAG treatment at birth rescued phenotypes associated with hippocampal deficits that occur in untreated adult Ts65Dn mice. This treatment resulted in behavioral improvements and normalized performance in the Morris water maze task for learning and memory. SAG treatment also produced physiological effects and partially rescued both N-methyl-d-aspartate (NMDA) receptor-dependent synaptic plasticity and NMDA/AMPA receptor ratio, physiological measures associated with memory. These outcomes confirm an important role for the hedgehog pathway in cerebellar development and raise the possibility for its direct influence in hippocampal function. The positive results from this approach suggest a possible direction for therapeutic intervention to improve cognitive function for this population.

A Comparison of Consumption and Recovery Profiles According to Anaesthetic Circuit Mode using a New Multifunctional Closed-Circuit Anaesthesia System during Desflurane Anaesthesia: A Clinical Study

This clinical study compared induction time, consumed anaesthetic dose, and haemodynamic and recovery profiles when using a new type of multifunctional anaesthesia machine (Zeus®) in semi-closed or closed circuit modes. Sixty female patients undergoing gynaecological surgery were randomly assigned to three groups and received desflurane anaesthesia through a semi-closed circuit (SCC) at fresh gas flow rates of 4 l/min (SCC 4 l/min) or 2 l/min (SCC 2 l/min), or through a closed circuit (CC). Anaesthesia was maintained at the minimum alveolar concentration for blocking the adrenergic response to painful stimulus (MACBAR) (4.6% end-tidal desflurane) during each operation. The time required to reach MACBAR was significantly shorter and the dose of desflurane was significantly smaller in the CC group compared with the other groups. There were no differences in haemodynamic and recovery profiles between the groups. It is concluded that the CC mode allowed a faster and more reliable induction, lower anaesthetic consumption and stable haemodynamic and recovery profiles.

Expression of DCC in differentiating ameloblasts from developing tooth germs in rats

OBJECTIVE

This study examined the expression pattern of the Deleted-in-colorectal-carcinoma (DCC) gene in developing rat tooth germs.

METHODS

Rat pups at 4, 7 and 10 d postpartum were used in this study. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescent localization were used to determine the level of DCC expression during tooth development.

RESULTS

There was more than 2-fold higher level of DCC mRNA in the rat 2nd maxillary molar tooth germs on 10 d postpartum, which was the root stage, than in the rat 3rd maxillary molar tooth germ, which was at the cap/early bell development stage. In addition, the levels of DCC mRNA in the 2nd maxillary molar germs at 4, 7 and 10 d postpartum increased gradually according to tooth development. Interestingly, immunoreactivity against DCC was specifically detected in the differentiating ameloblasts. DCC was observed in the lateral and apical sides of the newly differentiating and secretory stage ameloblasts. Afterwards, DCC was localized only in the apical side of the maturation stage ameloblasts, not in the lateral side.

CONCLUSION

DCC is expressed in the differentiating ameloblasts, which suggests that this molecule plays a crucial role in amelogenesis.