Biomedical subjects

Irina Alafuzoff

Publications and source records attributed to Irina Alafuzoff.

At least 19 recordsLinked to original sources

PubMed2006

Beta-amyloid aggregation in human brains with cerebrovascular lesions.

BACKGROUND AND PURPOSE: The present study assessed beta-amyloid (Abeta) protein aggregates in postmortem human brains in subjects who had experienced stroke to examine the proposed association between ischemic stress and the accumulation of Abeta reported in rodents. METHODS: A sample of 484 postmortem brains from nondemented subjects, lacking isocortical neurodegenerative pathology with verified cerebrovascular lesions, and 57 age-matched controls were assessed with respect to Abeta, Abeta40, and Abeta42 aggregates in the cortex and thalamus by immunohistochemical techniques. RESULTS: The load of Abeta aggregates did not display a significant association with cerebrovascular lesions. The load of Abeta, Abeta40, and Abeta42 aggregates increased with age, and there was a tendency toward higher odds ratios for Abeta aggregates, though not statistically significant, in subjects with acute cerebrovascular lesions. In the oldest subjects with cerebrovascular lesions and with both thalamic and cortical Abeta aggregates, the load of thalamic Abeta42 was significantly higher than the load of Abeta40. CONCLUSIONS: Our findings indicate that cerebrovascular disease does not influence the load of Abeta, whereas a shift of aggregation from the Abeta40 to the Abeta42 residue is noted in the thalamus but only in aged subjects. It is impossible, however, to state whether this result is attributable to increased Abeta production, its insufficient elimination, or other susceptibility factors.

Adult↗

PubMed2006

CSF phosphorylated tau protein correlates with neocortical neurofibrillary pathology in Alzheimer's disease.

Hyperphosphorylated tau protein (P-tau) in CSF is a core biomarker candidate of Alzheimer's disease. Hyperphosphorylation of tau is thought to lead to neurofibrillary changes, a neuropathological hallmark of this type of dementia. Currently, the question is unresolved whether CSF levels of P-tau reflect neurofibrillary changes within the brain of a patient with the illness. Twenty-six patients were included with intra-vitam CSF as well as post-mortem neuropathological data. In the CSF, P-tau phosphorylated at threonine 231 (P-tau231P) was analysed. Post-mortem, scores of neurofibrillary tangles (NFT) and neuritic plaques (NP) were assessed in frontal, temporal, parietal and hippocampal cortical areas. In the same cortical regions, load of hyperphosphorylated tau protein (HP-tau load) was determined. Concentrations of P-tau231P were measured in frontal cortex homogenates. We found significant correlations between CSF P-tau231P concentrations and scores of NFTs and HP-tau load in all neocortical regions studied. The score of NPs was correlated with CSF P-tau231P only within the frontal cortex. There was a correlation between P-tau231P in CSF and brain homogenates. These findings indicate that CSF P-tau231P may serve as an in vivo surrogate biomarker of neurofibrillary pathology in Alzheimer's disease.

Aged↗

PubMed2006

Staging of Alzheimer disease-associated neurofibrillary pathology using paraffin sections and immunocytochemistry.

Assessment of Alzheimer's disease (AD)-related neurofibrillary pathology requires a procedure that permits a sufficient differentiation between initial, intermediate, and late stages. The gradual deposition of a hyperphosphorylated tau protein within select neuronal types in specific nuclei or areas is central to the disease process. The staging of AD-related neurofibrillary pathology originally described in 1991 was performed on unconventionally thick sections (100 mum) using a modern silver technique and reflected the progress of the disease process based chiefly on the topographic expansion of the lesions. To better meet the demands of routine laboratories this procedure is revised here by adapting tissue selection and processing to the needs of paraffin-embedded sections (5-15 mum) and by introducing a robust immunoreaction (AT8) for hyperphosphorylated tau protein that can be processed on an automated basis. It is anticipated that this revised methodological protocol will enable a more uniform application of the staging procedure.

Alzheimer Disease↗

PubMed2006

Human brain tissue microarrays as a platform to investigate diseases of the nervous system.

We constructed tissue microarray (TMA) blocks containing post-mortem human brain tissue from subjects with clinically and neuropathologically verified Alzheimer's disease (AD), corticobasal degeneration (CBD), progressive supranuclear palsy, Lewy body disease, multisystem atrophy (MSA) as well as an age matched control. Fifteen donor blocks were merged into two TMA blocks containing 72, 2-mm punch core samples with representative brain regions generally affected in degenerative disorders. Hyperphosphorylated-gamma, alpha-synuclein and beta-amyloid-related pathologies were estimated. The diseases were easily recognized by evaluating the two TMA sections and the results assessing TMA sections were comparable with the assessment of the whole brain sections. The assessment of TMA sections revealed concomitant multifocal alpha-synuclein pathology in AD, mild tau-involvement in the case of MSA and a slight AD-type pathology in the case of CBD. These findings emphasize the importance of searching for a variety of pathologies in "the whole brain" rather than restricting the examination to a few vulnerable regions. Furthermore, the TMA methodology clearly reduced the number of sections needed for evaluating the whole brain, it increased the amount of research material generated and furthermore no detailed neuroanatomical knowledge was required for assessment of data.

Aged↗

PubMed2006

Assessments of the accumulation severities of amyloid beta-protein and hyperphosphorylated tau in the medial temporal cortex of control and Alzheimer's brains.

Alzheimer's disease (AD) is characterized neuropathologically by neuritic plaques (NPs), and neurofibrillary tangles (NFTs). So far, the following key issues are not yet answered to the disease: (1) the accumulation degrees of three Abeta variants, and tau phosphorylation epitopes in AD as compared to control; (2) the correlation degrees of levels of three Abeta variants with different tau phosphorylation epitopes; (3) the correlation degrees of levels of three Abeta variants and different tau phosphorylation epitopes with Braak and CERAD staging systems. To address these issues, levels of Abeta40, Abeta42, and Abeta43, and phosphorylated tau were assessed by dot blots in homogenates of the medial temporal cortex from AD and control brains in the present study. These data implied different roles of tau phosphorylation epitopes in formation of NFTs, and in this process, Abeta might play a key role. Assessments of levels of these abnormal proteins by dot blots may serve as a useful complement to the morphological evaluations in diagnosis of AD.

Aged↗

PubMed2006

Postmortem examination of vascular lesions in cognitive impairment: a survey among neuropathological services.

BACKGROUND AND PURPOSE: A full appreciation of the presence of cerebral vascular lesions in cognitively impaired patients can be ultimately reached at the neuropathological level. However, there are no detailed guidelines regarding what neuropathologists should look for at autopsy in cases of suspected vascular dementia or vascular cognitive impairment. We aimed at surveying the postmortem neuropathological procedures used in different centers in examining brain lesions of presumable or possible vascular origin in cognitively impaired patients. METHODS: Thirteen laboratories participated in the survey by filling in a semistructured questionnaire. We reviewed sampling and histology procedures in use and the neuropathological definitions of some of these lesions. Neuropathological criteria for the definition of a vascular origin of the dementing process were also surveyed. RESULTS: A large variability across centers was observed in the procedures used for the neuropathological examination and the histology techniques. Heterogeneity existed also in the definition of commonly found lesions (eg, white matter alterations, small vessel disease), interpretation of whether or not the lesions were reputed to be of vascular origin, and consequently in the interpretation of the cause of cognitive decline. CONCLUSIONS: The appreciation of the presence of neuropathologically verified vascular lesions in cognitively impaired cases may be heavily influenced by the laboratory tools used and also by the heterogeneity of the criteria applied in different centers. Harmonization of neuropathological procedures is badly needed in the field of vascular dementia and vascular cognitive impairment to better understand the association between various vascular lesions and clinical symptoms such as cognitive impairment.

Artifacts↗

PubMed2006

Collagen XVII is expressed in human CNS neurons.

Type XVII collagen (collagen XVII) is a component of hemidesmosomes, which connect epithelial cells to the underlying basement membrane. Previously, an association has been suggested between neurological disorders and the skin disease bullous pemphigoid, where autoimmunity is directed against collagen XVII. Furthermore, the lack of alpha6 integrin, a ligand of collagen XVII, has been implicated in defects of cortical organization in the mouse brain. In this study, we demonstrate for the first time the presence of collagen XVII in neurons of the human brain by in situ hybridisation, immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR). We propose that collagen XVII may be involved in the pathogenesis of various disorders affecting neuronal migration or synaptic plasticity.

Adult↗

PubMed2006

Case report: central neurocytoma with concomitant cerebral involvement by acute lymphatic leukemia.

Central neurocytomas are intraventricular tumors composed of round uniform cells. These tumors have usually favorable prognosis. Leukemic infiltrates are occasionally seen as a complication of acute lymphatic leukemia. This report describes a 7-year-old boy who was treated because of diagnosed lymphatic leukemia with central nervous system involvement and concomitant neurocytic tumor located in the fourth ventricle. These two entities might be problematic to differentiate from each other without proper histopathological examination.

Biomarkers, Tumor↗

PubMed2006

Human postmortem brain tissue and 2-mm tissue microarrays.

The authors constructed tissue microarray (TMA) blocks from human postmortem brain including numerous core samples measuring 2 mm in diameter from various anatomic regions. These TMA sections were then processed using various stainings and pretreatment techniques to evaluate their properties. The loss of core samples ranged from 2% to 100% and was significantly influenced by the type of glass slide used; it was lowest (2-8%) with SuperFrost Plus slides. The losses were not significantly altered when applying the most demanding pretreatment procedures or using human brain tissue with a long postmortem delay. A slight influence on the quality and the repeatability of some of the IHC stainings was seen by the postmortem delay, by the brain region, or by the glass slide used. One special feature of the constructed brain TMA block including many anatomic brain regions is that persons who lack skills in neuroanatomy can identify various brain structures simply by following the x-y coordinates. Thus, the applications of this brain TMA block in neurologic research by scientists with different skill bases remain to be determined.

Autopsy↗

PubMed2006

Interlaboratory comparison of assessments of Alzheimer disease-related lesions: a study of the BrainNet Europe Consortium.

This interlaboratory study evaluated the reproducibility of the assessments of neuritic plaques and neurofibrillary tangles (NFTs)--the hallmark lesions of Alzheimer disease--and compared the staining between the BrainNet Europe centers. To reduce the topography-related inconsistencies in assessments, we used a 2-mm tissue microarray (TMA) technique. The TMA block included 42 core samples taken from 21 paraffin blocks. The assessments were done on Bielschowsky and Gallyas silver stains using an immunohistochemical (IHC) method with antibodies directed to beta-amyloid (IHC/Abeta) and hyperphosphorylated tau (IHC/HPtau). The staining quality and the assessments differed between the participants, being most diverse with Bielschowsky (good/acceptable stain in 53% of centers) followed by Gallyas (good/acceptable stain in 57%) and IHC/Abeta (good/acceptable stain in 71%). The most uniform staining quality and assessment was obtained with the IHC/HPtau method (good/acceptable stain in 94% of centers). The neuropathologic diagnostic protocol (Consortium to Establish a Registry for Alzheimer Disease, Braak and Braak, and the National Institute of Aging and Reagan [NIA-Reagan] Institute) that was used significantly influenced the agreement, being highest with NIA-Reagan (54%) recommendations. This agreement was improved by visualization of NFTs using the IHC/HPtau method. Therefore, the IHC/HPtau methodology to visualize NFTs and neuropil threads should be considered as a method of choice in a future diagnostic protocol for Alzheimer disease.

Aged↗

PubMed2005

Proteomic analysis of glial fibrillary acidic protein in Alzheimer's disease and aging brain.

Chronic inflammation is known to play an important role in the heterogeneous pathogenesis of Alzheimer's disease (AD). Activated astrocytes expressing glial fibrillary acidic protein (GFAP) are closely associated with AD pathology, such as tangles, neuritic plaques and amyloid depositions. Altogether, 46 soluble isoforms of GFAP were separated and most of them quantified by two-dimensional immunoblotting in frontal cortices of AD patients and age-matched controls. A 60% increase in the amount of more acidic isoforms of GFAP was observed in AD and these isoforms were both phosphorylated and N-glycosylated, while more basic isoforms were O-glycosylated and exhibited no quantitative differences between post-mortem AD and control brains. These data highlight the importance of exploring isoform-specific levels of proteins in pathophysiological conditions since modifications of proteins determine their activity state, localization, turnover and interaction with other molecules. Mechanisms, structures and functional consequences of modification of GFAP isoforms remain to be clarified.

Aged↗

PubMed2005

Oxidative modification of proteins in the frontal cortex of Alzheimer's disease brain.

There is a large body of evidence highlighting the importance of oxidative stress in the pathogenesis of Alzheimer's disease (AD). We have previously standardised a method that can be applied to study oxidative changes in individual brain proteins by using two-dimensional oxyblots (Korolainen MA, Goldsteins G, Alafuzoff I, Koistinaho J, Pirttilä T. Proteomic analysis of protein oxidation in Alzheimer's disease brain. Electrophoresis 2002;23(19):3428-33). Here we have identified proteins that exhibited oxidative changes in AD when compared to age-matched controls and these protein changes have been further examined in relation to the neuropathological data. Indeed, several Tris-HCl soluble proteins tended to be less oxidised in AD when compared to controls. Two enzymes, mitochondrial glutamate dehydrogenase and cytosolic malate dehydrogenase, were increased in amount but showed significantly decreased degree of oxidation in AD brains when compared to controls. Furthermore, some changes related to the amounts or oxidation statuses of proteins were associated with the duration of the clinical impairment and also with the neuropathology. These results do not contradict the hypothesis of increased oxidative stress in AD but may represent co-existing compensatory changes in response to oxidative stress.

Aged↗

PubMed2005

Alpha-synuclein pathology does not predict extrapyramidal symptoms or dementia.

Intracytoplasmic aggregation of alpha-synuclein protein as Lewy bodies in the brainstem neurons is diagnostic for Parkinson's disease, whereas if this process also occurs in the cortical neurons, it is considered pathognomonic for dementia with Lewy bodies. However, the link between alpha-synuclein incorporation into inclusions, neuronal dysfunction, and clinical symptoms needs to be clarified. Another important issue of the pathogenetic puzzle is to understand where alpha-synuclein pathology begins and how it progresses in the brain. To study this, we collected all cases from autopsy material (N = 904) that had alpha-synuclein pathology in the dorsal motor nucleus of vagus, substantia nigra, and/or basal forebrain nuclei. In this way, our study has a unique design because the selection of material is entirely based on the presence of alpha-synuclein pathology regardless of clinical phenotype. Retrospective clinical assessment then showed that only 32 (30%) of 106 alpha-synuclein-positive cases were diagnosed with a neurodegenerative disorder. The distribution or load of alpha-synuclein pathology did not permit a dependable postmortem diagnosis of extrapyramidal symptoms or cognitive impairment. Some neurologically unimpaired cases had a reasonable burden of alpha-synuclein pathology in both brainstem and cortical areas, suggesting that alpha-synuclein-positive structures are not definite markers of neuronal dysfunction.

Aged↗

PubMed2005

Cystatin C expression is associated with granule cell dispersion in epilepsy.

Human temporal lobe epilepsy (TLE) is associated with cellular alterations (eg, hilar cell death, neurogenesis, and granule cell dispersion) in the dentate gyrus but their underlying molecular mechanism are not known. We previously demonstrated increased expression of cystatin C, a protease inhibitor linked to both neurodegeneration and neurogenesis, during epileptogenesis in the rat hippocampus. Here, we investigated cystatin C expression in the dentate gyrus in chronic epilepsy and its association with neuronal loss and neurogenesis. In both rats with epilepsy and human patients with TLE, cystatin C expression was increased in glial cells in the molecular layer of the dentate gyrus, being most prominent in cases with granule cell dispersion. In patients with TLE, high cystatin C expression associated with greater numbers of polysialylated neural cell adhesion molecule-positive newborn cells in the molecular layer, although the overall number was decreased, indicating that the newborn cells migrate to abnormal locations in the epileptic dentate gyrus. These data thus demonstrate that cystatin C expression is altered during the chronic phase of epilepsy and suggest that cystatin C plays a role in network reorganization in the epileptic dentate gyrus, especially in granule cell dispersion and guidance of migrating newborn granule cells.

Adolescent↗

PubMed2005

Subgroups of Alzheimer's disease based on cerebrospinal fluid molecular markers.

Alzheimer's disease, the most common cause of dementia, is multifactorial and heterogeneous; its diagnosis remains probable. We postulated that more than one disease mechanism yielded Alzheimer's histopathology, and that subgroups of the disease might be identified by the cerebrospinal fluid (CSF) levels of proteins associated with senile (neuritic) plaques and neurofibrillary tangles. We immunoassayed levels of tau, ubiquitin, and Abeta(1-42) in retrospectively collected CSF samples of 468 clinically diagnosed Alzheimer's disease patients (N = 353) or non-Alzheimer's subjects (N = 115). Latent profile analysis assigned each subject to a cluster based on the levels of these molecular markers. Alzheimer's disease was subdivided into at least five subgroups based on CSF levels of Abeta(1-42), tau, and ubiquitin; each subgroup presented a different clinical profile. These subgroups, which can be identified by CSF analysis, might benefit differently from different therapeutic drugs.

Aged↗

PubMed2005

Widespread and abundant alpha-synuclein pathology in a neurologically unimpaired subject.

The intracytoplasmic aggregation of alpha-synuclein (alphaS) protein is a common denominator for a group of neurodegenerative disorders currently known as synucleinopathies. It is generally assumed that the incorporation of alphaS protein into compact inclusions compromises the function and viability of its host cell via mechanical disruption. Herein, we report a widespread and abundant alphaS pathology in an elderly subject, whose medical history gave no indication of any neurodegenerative disease. We compared neuronal and glial components in this neurologically unimpaired subject with a patient with a clinical syndrome of dementia with Lewy bodies (DLB) by using a range of antigenic determinants and an in situ end-labeling technique. We detected no differences in vascular pathologies, in gliosis, or in apoptosis that would have explained the incompatible clinical end-points. With respect to the Alzheimer's disease-related changes, the only differences noted were the beta-amyloid aggregates in the putamen found in the DLB patient alone. Our findings suggest that there must be some currently unidentified factors rather than alphaS-positive inclusions that are responsible for the neuronal dysfunction. The alphaS-positive inclusions may well represent detoxified reserves that cells can tolerate for years, and thus prevention of their development could actually accelerate the diseases process.

Aged↗

PubMed2005

Levels of mTOR and its downstream targets 4E-BP1, eEF2, and eEF2 kinase in relationships with tau in Alzheimer's disease brain.

The pathogenesis of formation of neurofibrillary tangles (NFTs) in Alzheimer's disease (AD) brains is unknown. One of the possibilities might be that translation of tau mRNA is aberrantly regulated in AD brains. In the current study, levels of various translation control elements including total and phosphorylated (p) forms of mammalian target of rapamycin (mTOR), eukaryotic initiation factor 4E binding protein 1 (4E-BP1), eukaryotic elongation factor 2 (eEF2), and eEF2 kinase were investigated in relationship with tau in homogenates of the medial temporal cortex from 20 AD and 10 control brains. We found that levels of p-mTOR (Ser2481), and p-4E-BP1 (Thr70 and Ser65) dramatically increase in AD, and are positively significantly correlated with total tau and p-tau. Levels of p-eEF2K were significantly increased, and total eEF2 significantly decreased in AD, when compared to controls. The changes of p-mTOR (2481), p-4E-BP1, and p-eEF2 were immunohistochemically confirmed to be in neurons of AD brains. This suggested that there are obvious abnormalities of elements related with translation control in AD brain and their aberrant changes may up-regulate the translation of tau mRNA, contributing to hyperphosphorylated tau accumulation in NFT-bearing neurons.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Phosphorylated eukaryotic translation factor 4E is elevated in Alzheimer brain.

Eukaryotic translation factor 4E (eIF4E) plays a key role in regulating protein translation. It was thought that in order to maintain neuronal functions, tau protein is continuously generated to compensate those being hyperphosphorylated and compromised in its ability to promote and maintain microtubule assembly in Alzheimer's disease. If eIF4E is involved in tau mRNA translation, level of eIF4E phosphorylation should be changed. In the current study, we found a dramatic increase of phosphorylated eIF4E in Alzheimer's disease, especially in those cases with late stages of neurofibrillary changes. Level of eIF4E phosphorylation is significantly correlated with total- and Alzheimer hyperphosphorylated taus. These data suggest that the increase of eIF4E phosphorylation is involved in formation of Alzheimer neurofibrillary changes.

Aged↗