ABSTRACT
Parkinson's disease (PD) is a neurodegenerative disorder involving several neuronal systems. Impaired olfactory function may constitute one of the earliest symptoms of PD. However, it is still unclear to what degree changes of the olfactory epithelium may contribute to dysosmia and if these changes are different from those of other hyposmic or anosmic patients. This study aimed to investigate the hypothesis that olfactory loss in PD is a consequence of specific PD-related damage of olfactory epithelium. Biopsies of 7 patients diagnosed with PD were taken. Six patients with PD were hyposmic, one anosmic. As non-PD controls served 9 patients with hyposmia, 9 with anosmia, and 7 normosmic individuals. Further, nasal mucosa of 4 postmortem individuals was investigated. Immunohistochemical examinations were performed with antibodies against olfactory marker protein (OMP), protein gene product 9.5 (PGP 9.5), beta-tubulin, (BT), proliferation-associated antigen (Ki 67), the stem cell marker nestin, cytokeratin, p75NGFr, and alpha-synuclein. Most of the biopsy specimens exhibited irregular areas of olfactory-like, dysplastic epithelium positive for either PGP 9.5 or BT, but negative for OMP. No major histochemical differences in either the expression or distribution of these proteins were observed in the olfactory epithelium of patients with PD compared with controls. Reverse transcription PCR (RT-PCR) data indicated mRNA for OMP in almost all subjects, independently of their olfactory performance. These data support the idea that olfactory loss in Parkinson's disease is not a consequence of damage to the olfactory epithelium but rather results from distinct central-nervous abnormalities.
Subject(s)
Olfactory Mucosa/pathology , Parkinson Disease/pathology , Adult , Age Factors , Aged , Biopsy/methods , Female , Forkhead Transcription Factors/metabolism , Humans , Ki-67 Antigen/metabolism , Male , Middle Aged , Nerve Tissue Proteins/metabolism , Olfaction Disorders/etiology , Olfaction Disorders/metabolism , Olfaction Disorders/pathology , Olfactory Marker Protein/genetics , Olfactory Marker Protein/metabolism , Olfactory Mucosa/metabolism , Parkinson Disease/complications , Receptors, Nerve Growth Factor/metabolism , Ubiquitin Thiolesterase/metabolism , Young AdultABSTRACT
BACKGROUND: The ambystomatid salamander, Ambystoma mexicanum (axolotl), is an important model organism in evolutionary and regeneration research but relatively little sequence information has so far been available. This is a major limitation for molecular studies on caudate development, regeneration and evolution. To address this lack of sequence information we have generated an expressed sequence tag (EST) database for A. mexicanum. RESULTS: Two cDNA libraries, one made from stage 18-22 embryos and the other from day-6 regenerating tail blastemas, generated 17,352 sequences. From the sequenced ESTs, 6,377 contigs were assembled that probably represent 25% of the expressed genes in this organism. Sequence comparison revealed significant homology to entries in the NCBI non-redundant database. Further examination of this gene set revealed the presence of genes involved in important cell and developmental processes, including cell proliferation, cell differentiation and cell-cell communication. On the basis of these data, we have performed phylogenetic analysis of key cell-cycle regulators. Interestingly, while cell-cycle proteins such as the cyclin B family display expected evolutionary relationships, the cyclin-dependent kinase inhibitor 1 gene family shows an unusual evolutionary behavior among the amphibians. CONCLUSIONS: Our analysis reveals the importance of a comprehensive sequence set from a representative of the Caudata and illustrates that the EST sequence database is a rich source of molecular, developmental and regeneration studies. To aid in data mining, the ESTs have been organized into an easily searchable database that is freely available online.
