Neurobiology of Alzheimer's Disease

Alzheimer's disease(AD) is associated with a characteristic neuropathology. The major hallmarks of AD are senile plaques(SPs) and neurofibrillary tangles(NFTs). beta-amyloid protein(Abeta) is derived from the proteolysis of amyloid precursor protein(APP) and then converted to SPs. Mature SPs produce cytotoxicity through direct toxic effects and activation of microglia and complement. NFTs are composed of paired helical filaments(PHFs) including abnormally phosphorylated form of the microtubule-associated protein(MAP) tau and increased tau level in cerebrospinal fluid may be observed in most AD. The aggregation of Abeta and tau formation are thought to be a final common pathway of AD. Acetycholine, dopamine, serotonin, GABA and their receptors are associated with AD. Especially, decreased nicotinic acetylcholine receptors(nAChRs) in AD are reported. Genetic lesions associated with AD are mutations in the structural genes for the APP located on chromosome 21, presenilin(PSN)1 located on chromosome 14 and PSN2 located on chromosome 1. Also, trisomy 21, Apo-E gene located on chromosome 19, PMF locus, low density lipoprotein receptor-related protein and alpha-macroglobulin increase risk of AD. In this article, we will review about the neurobioloby of AD and some newly developed research areas.

Operative Treatment of Lumbar Spondylolisthesis using Steffee VSP and Cut Pedicle Screw: New Operative Technique / 대한척추외과학회지

STUDY DESIGN: The authors have investigated the clinical results for the lumbar spondylolisthesis treated operatively using the Steffee VSP and cut pedicle screw for satisfactory reduction with saving of functioning segment. OBJECTIVES: To demonstrate the effectiveness of short segment fusion using the Steffee VSP and cut pedicle screw. SUMMARY OF LITERATURE REVIEW: Spondylolisthesis has been recognized as one of the leading cause of low back pain. Most are successfully managed with conservative treatment, but operative treatment is indicated if conservative treatment fails. Operative treatments are categorized into decompression, reduction and fusion. Especially, in the methods of fusion, there are some controversies between short segment fusion for saving of functioning segment and extended fusion for more amount of reduction. MATERIALS AND METHODS: We report 29 cases of lumbar spondylolisthesis which were treated operatively using the Steffee VSP and cut pedicle screw from March 1994 to Feb. 1996. The reduction was done by cork screw pulling back mechanism and the short segment fusion was done. The each case was followed up for 1 year 6 months to 3 years 1 month. RESULTS: Satisfactory reduction was obtained from preoperative 23.3% slippage to postoperative 3.7% by Taillard method. In the functional results, 90% was above good according to the Gill`s criteria without any serious complications. CONCLUSIONS: We had satisfactory results after this operation. When compared to operative treatment with S-shaped VSP reported by same authors, this procedure had following advantages ; ease to make and decrease of complication such as laminar sclerosis due to wider contact. It is necessary that long-term follow up about pressure effect of cut pedicle screw on above facet joint and lamina, fusion rate and saving of above functioning segment after implant removal.