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In order to investigate the mechanisms responsible for adaptation to altered gravity, we assessed the changes in mRNA expression of glutamate receptors in vestibular ganglion cells, medial vestibular nucleus, spinal vestibular nucleus/lateral vestibular nucleus, cerebellar flocculus, and uvula/nodulus from rats exposed to hypergravity for 2 h to 1 week using real-time quantitative RT-PCR methods. The mRNA expression of GluR2 and NR1 receptors in the uvula/nodulus and NR1 receptors in the medial vestibular nucleus increased in animals exposed to 2 h of hypergravity, and it decreased gradually to the control level. The mRNA expression of GluR2 receptors in vestibular ganglion cells decreased in animals exposed to 1 week of hypergravity. Neither the metabotropic glutamate receptor 1 nor δ2 glutamate receptor in flocculus and uvula/nodulus was affected by a hypergravity load for 2 h to 1 week. It is suggested that the animals adapted to the hypergravity by enhancing the cerebellar inhibition of the vestibular nucleus neurons through activation of the NR1 and GluR2 receptors on the Purkinje cells in uvula/nodulus especially at the early phase following hypergravity. In the later phase following hypergravity, the animals adapted to the hypergravity by reducing the neurotransmission between the vestibular hair cells and the primary vestibular neurons via down-regulation of the postsynaptic GluR2 receptors in the vestibular periphery. [ABSTRACT FROM AUTHOR]

Objectives: Recently, we identified three novel mutations of the GJB2 gene in Japanese families with autosomal-recessive non-syndromic deafness.1 Seven of 11 mutated chromosomes (63.6%) contained a 233delC allele, suggesting that the 233delC mutation is the most common mutation of the GJB2 gene in the Japanese population. After it was recognized that cochlear implantation (CI) is of benefit to children with prelingual deafness, we have had a number of prelingual pediatric CI patients. Because children carrying the homozygous 233delC mutation show bilateral prelingual profound deafness, they could be enrolled in the CI program at Osaka University Graduate School of Medicine. The purposes of this study were 1) to analyze the occurrence of the GJB2 mutations in our 15 prelingual pediatric CI patients in whom the cause of non-syndromic deafness was unknown, and 2) to evaluate the auditory function and postoperative speech perception with CI of those GJB2-related deaf subjects.Study Design: Retrospective analysis.Methods: Mutation analysis of the GJB2 gene by direct sequencing was performed with genomic DNA from 15 children born profoundly deaf as a result of unknown causes and implanted with CI. Intraoperative electrically evoked auditory brainstem response (EABR) and intra-/postoperative EAP were measured. The speech perception was evaluated with Infants and Toddlers Meaningful Auditory Integration Scale (IT-MAIS).Results and Conclusions: We identified 4 CI patients (26.7%) out of 15 children carrying the homozygous 233delC mutation. Intra- and postoperative evaluation of the auditory system revealed almost intact cochlear and retrocochlear auditory function in these 4 patients. Postoperative auditory testing indicates that their speech perception had become significantly higher in comparison with that of other prelingual CI patients. These results suggest that prelingual deaf children carrying the homozygous 233delC mutation of the GJB2 gene can benefit from CI. [ABSTRACT FROM AUTHOR]

The cell nature of follicular dendritic cells (FDC), a member of dendritic cell group, was examined to see whether or not they are recirculating cells on splenic implantation study. Slices of BALB/c mouse spleen were implanted into C57BL/6 mice neonatally thymectomized and reconstructed by F1 (BALB/c × C57BL/6) thymus grafting. On H-2 class I immunohistology 6 months later, host spleens consisted of only the cells including FDC of host (C57BL/6) type. On the other hand, FDC of regenerated splenic grafts were of splenic donor (BALB/c) origin and haematogenic cells including germinal centre lymphocytes were of the host (C57BL/6) origin. The fact that the FDC in the regenerated spienic grafts reside irrespective of the replacement by host recirculating cells indicates that FDC belong primarily to stationary cell populations but not recirculating cell populations. [ABSTRACT FROM AUTHOR]