Yoshiko Furiya

Amyloid β protein 42(43) in cerebrospinal fluid of patients with Alzheimer's disease

To investigate the pathomechanism of amyloid β protein (Aβ) deposition in brains with Alzheimers disease (AD), cerebrospinal fluid (CSF) levels of Aβ species (CSF-Aβ) with different carboxy termini, i.e. AβX-40 and AβX-42(43) as well as Aβ1-40 and Aβ1-42(43), were measured in patients with AD and age-matched controls without dementia (CTR) using sandwich enzyme-linked immunosorbent assays (ELISAs). The present study revealed that both CSF-AβX-42(43) and Aβ1-42(43) levels were significantly lower in the AD patients (P<0.005) than in the CTR group, whereas neither CSF-AβX-40 nor CSF-Aβ1-40 levels showed any differences between the two groups. In addition, although there was no difference between the ratios of AβX-40 to Aβ1-40 in the AD and CTR groups, the ratios of AβX-42(43) to Aβ1-42(43) were increased in the AD group compared with those in the CTR group (P<0.05). Therefore, it can be assumed that amino the ratios of terminal truncations and/or modifications of CSF-Aβ42(43) with carboxy termini ending at residue 42(43) were more increased in the AD group than in the CTR group. Increased adsorption of Aβ42(43) to Aβ deposition in AD brains, decreased secretion of Aβ42(43) to CSF and/or increased clearance of Aβ42(43) from CSF might explain the diminished levels of Aβ42(43) in the CSF of AD patients. In addition, CSF-Aβ42(43) could reflect increased amino terminal truncations and/or modifications of Aβ42(43) in AD brains.

Tau in cerebrospinal fluids: establishment of the sandwich ELISA with antibody specific to the repeat sequence in tau

Clinical diagnosis for Alzheimers disease (AD) is provided by the criteria of DSMIV and clinical progress in addition to imaging analysis with MRI after negative screening. The final exclusive diagnosis is confirmed by the neuropathological findings of neurofibrillary tangles and senile plaques in autopsy brains. We developed a new ELISA system to measure the amount of tau in cerebrospinal fluids (CSF) using phosphorylation-independent and sequence-specific antibodies. The present ELISA was sensitive enough to detect tau in CSF of normal subjects. The amount of tau was significantly elevated in CSF of AD subjects compared with those of normal subjects and subjects with dementia of cerebrovascular disease, suggesting that tau in CSF reflects the massive and continuous neuronal cell death in the AD brain. In conclusion, we established an ELISA system which enabled us to detect tau in CSF and demonstrated that tau was significantly and specifically elevated in CSF of AD subjects. This assay system can provide us with a potent diagnostic tool for clinical AD.

Increased CSF tau protein in corticobasal degeneration

Abstract Using a sensitive sandwich enzyme-linked immunosorbent assay (ELISA) method, we measured the concentration of total tau protein in the cerebrospinal fluid (CSF) from nine patients with corticobasal degeneration (CBD) in comparison with 12 normal control subjects in order to assess its diagnostic value. The CSF concentration of tau in patients with CBD (0.69, 0.20 ng/ml: mean, SD) was higher than that in the normal controls (0.48, 0.14 ng/ml, P = 0.0076 unpaired t test). This increase in CBD patients may reflect widespread tau pathology in CBD, but should be interpreted with reserve as an aid to diagnosis.

Plasma levels of amyloid β 40 and 42 are independent from ApoE genotype and mental retardation in down syndrome

In Down syndrome (DS) brain an early, selective accumulation of amyloid beta (Abeta) peptides ending at residue 42 (Abeta42) occurs. Whether this event depends on an altered processing of amyloid beta precursor protein (APP) or on defective clearance is uncertain. To investigate this issue, we measured Abeta species 40 and 42 in plasma from 61 patients with DS, 77 age-matched normal controls, and 55 mentally retarded subjects without chromosomal abnormalities. The Abeta 40 and 42 plasma levels were then correlated with apolipoprotein E (apoE) genotypes in all groups of cases, and with I. Q. and Mini Mental Status Examination values in DS subjects. Both Abeta species were significantly elevated in DS compared to control groups, and the extent of their increase reflects that expected from APP gene overexpression. Plasma levels of Abeta 40 and 42 did not correlate with apoE genotypes in DS and control cases, and with the extent of mental retardation in DS subjects. The results indicate that accumulation and clearance of plasma and cerebral Abeta are regulated by different and independent factors.

Glial tau-positive structures lack the sequence encoded by exon 3 of the tau protein gene

Tau protein comprises six distinct isoforms defined by the presence or absence of sequences encoded by alternatively spliced exon 2, 3 and 10. We have investigated immunohistochemically the expression of exon 3-derived fragment (E-3) of tau protein in brains of patients with Alzheimers disease (AD) and other neurodegenerative diseases in which the abnormal accumulation of tau protein takes place. In AD, a subset of neurofibrillary tangles, neuropil threads and dystrophic neurites in senile plaques were stained positively with an anti-E-3 antibody. In sharp contrast, glial tau-positive structures, such as astrocytic plaques and oligodendroglial coiled bodies, were negative for E-3 in all cases examined in this study. This is the first report to discriminate tau-positive inclusions in glial cells from those in neurons at the molecular level.

Chrysamine G and its derivative reduce amyloid β-induced neurotoxicity in mice

Abstract The neurotoxicity of amyloid β (Aβ) is widely believed to play a seminal role in neurodegeneration in Alzheimers disease. We examined the effect of Chrysamine G (CG) on such neurotoxicity using the specific measurement of surviving neurons. CG was found to reduce the neurodegeneration induced by both the active short fragment of Aβ 25–35 and full-sized Aβ 1–40 . In this study, we synthesized a new chemical compound from a monovalent structure of CG (hCG), with a lower affinity for Aβ, and compared its activity with that of CG. Both CG and hCG were found to be equally efficacious in reducing Aβ-induced neuronal death at a concentration of 0.1–1 μM, indicating that the mechanism of action for CG was not due to its chelating activity, but rather due to its anti-oxidant activity.

Okadaic acid enhances abnormal phosphorylation on tau proteins

Tau proteins are one of the microtubule-associated proteins (MAPs) and show promoting activity on microtubule assembly. Tau proves to be the major constituent of Alzheimers paired helical filaments, in which tau is found to be different from normal tau in that it is abnormally phosphorylated. To examine the effect of the abnormal phosphorylation on microtubule assembly, we obtained abnormally phosphorylated tau that was made in vitro by hyperphosphorylation with ATP or with ATP and okadaic acid, a drug inhibiting phosphatase, mainly 1 and 2A. We confirmed the biochemical properties of abnormally phosphorylated tau based on its retarded gel mobility and immunoreactivity to anti-PHF. We found that abnormally phosphorylated tau was able to promote the polymerization of microtubules but showed less activity as compared with normally phosphorylated tau. This effect of ATP on abnormal phosphorylation of tau was enhanced when okadaic acid was added in the phosphorylation reaction mixture during microtubule assembly. It is of significance that phosphatase activity as well as kinase activity are involved in the formation of abnormal tau. The present evidence suggests the simultaneous occurrence of microtubule disassembly and the pathogenesis of paired helical filaments following the abnormal phosphorylation of tau.

Rivastigmine Improves Appetite by Increasing the Plasma Acyl/Des-Acyl Ghrelin Ratio and Cortisol in Alzheimer Disease

Background: Weight loss accelerates cognitive decline and increases mortality in patients with dementia. While acetylcholinesterase (AChE) inhibitors are known to cause appetite loss, we sometimes encounter patients in whom switching from donepezil (AChE inhibitor) to rivastigmine (AChE and butyrylcholinesterase [BuChE] inhibitor) improves appetite. Since BuChE inactivates ghrelin, a potent orexigenic hormone, we speculated that rivastigmine improves appetite by inhibiting BuChE-mediated ghrelin inactivation. Methods: The subjects were patients with mild to moderate Alzheimer disease treated with either rivastigmine patch (n = 11) or donepezil (n = 11) for 6 months. Before and after treatment, we evaluated appetite (0, decreased; 1, slightly decreased; 2, normal; 3, slightly increased; 4, increased), cognitive function, and blood biochemical variables, including various hormones. Results: Rivastigmine treatment significantly improved appetite (from 1.6 ± 0.5 to 2.6 ± 0.7), whereas donepezil treatment did not (from 2.0 ± 0.0 to 1.8 ± 0.4). Simultaneously, rivastigmine, but not donepezil, significantly decreased the serum cholinesterase activity (from 304.3 ± 60.5 to 246.8 ± 78.5 IU/L) and increased the cortisol level (from 11.86 ± 3.12 to 14.61 ± 3.29 μg/dL) and the acyl/des-acyl ghrelin ratio (from 4.03 ± 2.96 to 5.28 ± 2.72). The levels of leptin, insulin, total ghrelin, and cognitive function were not significantly affected by either treatment. Conclusions: Our results suggest that compared with donepezil, rivastigmine has the advantage of improving appetite by increasing the acyl/des-acyl ghrelin ratio and cortisol level, thereby preventing weight loss.

Step Numbers and Hoehn-Yahr Stage after Six Years

Background: Freezing of gait (FOG) has been linked to increased numbers of steps taken while walking. We tested the hypothesis that an increased number of steps associated with FOG might predict the exacerbation of the severity of Parkinson’s disease (PD). Methods: We prospectively studied 26 patients. Clinical assessments were performed and balance was evaluated in 30 patients with Hoehn-Yahr stage III PD 6 years previously. Gait parameters were analyzed with the use of an originally designed, suddenly narrowed path. PD-related independent variables, balance investigation-related variables, and gait-independent-related variables were analyzed by multiple logistic regression analysis. Results: The Hoehn-Yahr stage increased in 14 patients and was unchanged in 12 patients. The 36-item Short-Form Health Survey score (OR 1.079, p = 0.041, 95% CI 1.003–1.161) and the number of steps on the suddenly narrow path (OR 1.605, p = 0.047, 95% CI 1.006–2.56) were related to an increase in the Hoehn-Yahr stage. The number of steps was significantly higher on the suddenly narrowed path (11.3 ± 3.6) than on a straightly narrowed path (10.1 ± 3.2) at the time of final follow-up in the 26 patients (p < 0.001). Conclusions: An increased number of steps associated with FOG, which was elicited by the suddenly narrowed path, might be one predictor of an upgrade of stage in patients with Hoehn-Yahr stage III PD.