The impact of argyrophilic grain disease on the development of dementia and its relationship to concurrent Alzheimer's disease-related pathology.

Argyrophilic grain disease (AGD) constitutes a neurodegenerative disorder that occurs in the brains of the elderly and affects 5% of all patients with dementia. Tau protein-containing lesions known as argyrophilic grains and located predominantly in limbic regions of the brain characterize this disease. Dementia is encountered in only a subset of cases that display the morphological pattern of AGD. The aim of this study is to determine the role of concurrent Alzheimer's disease (AD)-related pathology for the development of dementia in AGD patients. A total of 204 post-mortem brains from 30 demented and 49 nondemented AGD patients, 39 AD patients, and from 86 nondemented controls without AGD were staged for AD-related neurofibrillary tangles (NFTs) as well as amyloid beta-protein (Abeta) deposition. To identify differences in AD-related pathology between demented and nondemented AGD cases, and to differentiate the pattern of AD-related changes in demented and nondemented AGD cases from that seen in AD and nondemented controls, we statistically compared the stages of Abeta and NFT distribution among these groups. Using a logistic regression model, we showed that AGD has a significant effect on the development of dementia beyond that attributable to AD-related pathology (P < 0.005). Demented AGD cases showed lower stages of AD-related pathology than did pure AD cases but higher stages than nondemented AGD patients. AGD associated dementia was seen in the presence of NFT (Braak)-stages II-IV and Abeta-phases 2-3, whereas those stages were not associated with dementia in the absence of AGD. In conclusion, AGD is a clinically relevant neurodegenerative entity that significantly contributes to the development of dementia by lowering the threshold for cognitive deficits in the presence of moderate amounts of AD-related pathology.

Extended pathoanatomical studies point to a consistent affection of the thalamus in spinocerebellar ataxia type 2.

The involvement of the thalamus during the course of the currently known polyglutamine diseases is still a matter of debate. While it is well-known that this diencephalic nuclear complex undergoes neurodegeneration in some polyglutamine diseases such as Huntington's disease (HD), it has remained unclear whether and to what extent the thalamus is also involved in spinocerebellar ataxia type 2 (SCA2) patients. Encouraged by our recent post-mortem findings in one German SCA2 patient and the results of a recent nuclear magnetic resonance (NMR) study, we extended our pathoanatomical analysis to serial thick sections stained for lipofuscin granules and Nissl substance through the thalami of four additional German and Cuban SCA2 patients. According to this analysis the thalamus is consistently affected by the destructive process of SCA2. In particular, during our study we observed a consistent involvement of the lateral geniculate body, the lateral posterior, ventral anterior, ventral lateral, ventral posterior lateral, and ventral posterior medial thalamic nuclei as well as the extraterritorial reticular nucleus. In four of the SCA2 cases studied additional damage was seen in the inferior and lateral nuclei of the pulvinar, whereas in the minority of the patients a subset of the limbic nuclei of the thalamus (i.e. anterodorsal, anteroprincipal, laterodorsal, fasciculosus, mediodorsal, central lateral, central medial, cucullar, and paracentral nuclei, medial nucleus of the pulvinar) underwent neurodegeneration. These interindividual differences in the distribution pattern of thalamic neurodegeneration indicate that the thalamic nuclei differ in their proclivities to degenerate in SCA2 and may suggest that they become involved at different phases in the evolution of the underlying degenerative process.

Damage to the reticulotegmental nucleus of the pons in spinocerebellar ataxia type 1, 2, and 3.

BACKGROUND: The reticulotegmental nucleus of the pons (RTTG) is among the precerebellar nuclei of the human brainstem. Although it represents an important component of the oculomotor circuits crucial for the accuracy of horizontal saccades and the generation of horizontal smooth pursuits, the RTTG has never been considered in CAG repeat or polyglutamine diseases. METHODS: Thick serial sections through the RTTG of 10 patients with spinocerebellar ataxias (SCAs) assigned to the CAG repeat or polyglutamine diseases (2 SCA-1 patients, 4 SCA-2 patients, and 4 SCA-3 patients) were stained for neuronal lipofuscin pigment and Nissl material. RESULTS: The unconventionally thick tissue sections revealed the hitherto overlooked involvement of the RTTG in the degenerative processes underlying SCA-1, SCA-2, and SCA-3, whereby in one of the SCA-1 patients, in two of the SCA-2 patients, and in all of the SCA-3 patients, the RTTG underwent a conspicuous loss of its nerve cells. CONCLUSIONS: Neurodegeneration may not only affect the cranial nerve nuclei (i.e., oculomotor and abducens nuclei) of SCA-1, SCA-2 and SCA-3 patients integrated into the circuits, subserving accuracy of horizontal saccades and the generation of horizontal smooth pursuits, but likewise involves the premotor networks of these circuits. This may explain why the SCA-1, SCA-2, and SCA-3 patients in this study with a heavily damaged reticulotegmental nucleus of the pons developed dysmetric horizontal saccades and impaired smooth pursuits during the course of the disease.

Degeneration of the central vestibular system in spinocerebellar ataxia type 3 (SCA3) patients and its possible clinical significance.

Although the vestibular complex represents an important component of the neural circuits crucial for the maintenance of truncal and postural stability, and it is integrated into specialized oculomotor circuits, knowledge regarding the extent of the involvement of its nuclei and associated fibre tracts in cases with spinocerebellar ataxia type 3 (SCA3) is incomplete. Accordingly, we performed a pathoanatomical analysis of the vestibular complex and its associated fibre tracts in four clinically diagnosed and genetically confirmed SCA3 patients with the aim of providing more exact information as to the involvement of the vestibular system in this disorder. By means of unconventionally thick serial sections through the vestibular nuclei stained for lipofuscin pigment and Nissl material, we could show that all five nuclei of this complex (interstitial, lateral, medial, spinal, and superior vestibular nuclei) are subject to neurodegenerative processes in SCA3, whereby examination of thick serial sections stained for myelin revealed that all associated fibre tracts (ascending tract of Deiters, juxtarestiform body, lateral and medial vestibulospinal tracts, medial longitudinal fascicle, vestibular portion of the eighth cranial nerve) underwent atrophy and demyelinization in all four of the patients studied. The reported lesions can help to explain the truncal and postural instability as well as the impaired optokinetic nystagmus, vestibulo-ocular reaction, and horizontal gaze-holding present in SCA3 cases.

Genetic association of argyrophilic grain disease with polymorphisms in alpha-2 macroglobulin and low-density lipoprotein receptor-related protein genes.

Argyrophilic grain disease (AGD) is a neurodegenerative disorder of the aged human brain associated with the formation of abnormal tau protein in specific neurones and macroglial cells. Previously, we reported the association between AGD and the epsilon2 allele of apolipoprotein E (ApoE). Here, the polymorphisms of the alpha-2 macroglobulin gene (A2M) and those of the low-density lipoprotein receptor-related protein gene (LRP) were assessed in 115 AGD cases and compared with 170 controls. The results reveal an association between AGD and the C766T polymorphism of LRP (P=0.001). In addition, the present study shows that the valine to isoleucine (Val1000Ile) polymorphism of A2M is linked with AGD (P=0.03). By comparison, no relationship between AGD and the intronic 5-bp deletion/insertion polymorphism of A2M is demonstrable (P=0.8). Finally, this report corroborates and extends our earlier finding in that the frequency of the epsilon2 allele of ApoE is higher in AGD cases than in controls (17.4% vs. 8.5%, P=0.003), whereas the epsilon4 allele frequency approximates that in control cases (13.9% vs. 13.2%, P=0.93). This association, however, is only apparent in the presence of the LRP CC genotype. In conclusion, the present study shows that AGD is associated with the LRP, A2M and ApoE genes.

UV light-induced autofluorescence of full-length Abeta-protein deposits in the human brain.

The formation of amyloid plaques is a hallmark of Alzheimer's disease (AD). Amyloid plaques and vascular amyloid deposits in cerebral amyloid angiopathy (CAA) consist of the beta-amyloid protein (Abeta) in association with other proteins. These Abeta-deposits can be visualized by thioflavin S, Congo red staining, silver staining methods and immunohistochemistry. Senile plaques also have been shown to exhibit blue autofluorescence. Here we report that UV light-induced autofluorescence is restricted to full-length Abeta-containing amyloid plaques and is also seen in blood vessels affected by CAA. Different types of samples from AD and control cortices were examined: native samples, formalin-fixed paraffin and polyethylene glycol-embedded tissue sections. These samples were viewed with a fluorescence microscope under UV light excitation (360 - 370 nm). By emitting blue fluorescence (>420 nm), amyloid plaques and blood vessels affected by CAA were detected in AD and CAA samples. Combination with immunofluorescence against anti-Abeta1-42, anti-Abeta17-24, and anti-Abeta8-17 demonstrated co-localization of the autofluorescent deposits with full-length Abeta containing Abeta-deposits. N-terminal truncated Abeta-deposits, such as the fleecy amyloid, do not exhibit autofluorescence. In doing so, Abeta-autofluorescence is a suitable method for screening native tissue samples for full-length Abeta-deposits. In contradistinction to conventional and immunohistochemical procedures, detection of plaques and CAA by autofluorescence enables the recognition of full-length Abeta-deposits in the human brain without any chemical interaction whatsoever on the part of Abeta.

Parkinson's disease: the thalamic components of the limbic loop are severely impaired by alpha-synuclein immunopositive inclusion body pathology.

The Parkinson's disease (PD)-related inclusion body pathology comprises Lewy bodies (LBs) as well as Lewy neurites (LNs). The distribution and severity of this pathology were investigated in the thalamus of 12 autopsy cases with clinically diagnosed and neuropathologically confirmed PD. The LBs and LNs were visualized by immunoreactions against the protein alpha-synuclein. In the human thalamus during PD, a specific and highly stereotypical distribution pattern of LBs and LNs evolves. As in cortical and other subcortical regions, the components of human thalamus assigned to the limbic loop bear the brunt of the PD-related pathology. In contrast, the thalamic components integrated into the striatal and cerebellar loops as well as the primary sensory nuclei of the thalamus show at best a mildly developed pathology. Damage to the thalamic components of the limbic loop nuclei may contribute not only to the cognitive, emotional, and autonomic symptoms of PD but to the somatomotor and oculomotor dysfunctions as well.

Gender and age modify the association between APOE and AD-related neuropathology.

OBJECTIVE: To assess the impact of apolipoprotein E (APOE) polymorphism on AD-related neurofibrillary tangle (NFT) formation and senile plaques (SP). METHODS: A sample of 729 routine autopsy brains (359 men, 370 women; age range, 60 to 99 years) was investigated. All brains were classified neuropathologically according to a procedure permitting differentiation of six NFT stages and three SP stages. APOE genotyping was performed on all cases. RESULTS: The epsilon4 allele of APOE was associated not only with SP (p < 0.0001) but also with NFT formation (p < 0.0001). The effect of the epsilon4 allele on NFT formation was noted at ages > or =80 years (p < 0.0001) but not between ages 60 and 79 years (p = 0.12). An association between the epsilon4 allele and SP for women was found at ages 60 to 79 years (p < 0.0001) but not at > or =80 years of age (p = 0.063). By comparison, men showed an association in both age categories (p = 0.001 and p = 0.001). CONCLUSION: The results confirm the association between the epsilon4 allele and both types of AD-related lesions and show that this association is differentially modified by age and gender.

Sequence of Abeta-protein deposition in the human medial temporal lobe.

The deposition of Abeta protein (Abeta) and the development of neurofibrillary changes are important histopathological hallmarks of Alzheimer disease (AD). In this study, the medial temporal lobe serves as a model for the changes in the anatomical distribution pattern of different types of Abeta-deposits occurring in the course of AD, as well as for the relationship between the development of Abeta-deposition and that of neurofibrillary pathology. In the first of 4 phases of beta-amyloidosis, diffuse non-neuritic plaques are deposited in the basal temporal neocortex. The same plaque type appears in the second phase within the external entorhinal layers pre-beta and pre-gamma, and fleecy amyloid deposits occur in the internal entorhinal layers pri-alpha, pri-beta, pri-gamma, and in CA1. In the third phase, Abeta-deposits emerge in the molecular layer of the fascia dentata, and band-like Abeta-deposits occur in the subpial portion of the molecular layer of both the entorhinal region and the temporal neocortex. In addition, confluent lake-like Abeta-deposits appear in the parvopyramidal layer of the presubicular region. The fourth phase is characterized by diffuse and core-only plaques in CA4. Diffuse plaques evolve sporadically in the external entorhinal layer pre-alpha. Parallel to the evolution of beta-amyloidosis as represented by the 4 phases, neuritic plaques gradually make their appearance in the temporal neocortex, entorhinal region, CA1, the molecular layer of the fascia dentata, and CA4. A prerequisite for their development is the presence of Abeta and the presence of neurofibrillary tangles in neurons targeting the regions where neuritic plaques evolve. Each of the different types of Abeta-deposits, including neuritic plaques, plays a specific role in the distinct developmental sequence as represented by the 4 phases so that the medial temporal lobe inexorably becomes involved to an ever greater extent. The step-for-step involvement of connected anatomical subfields highlights the importance of the entorhino-hippocampal pathways for the expansion of beta-amyloidosis. The 4 phases in the evolution of beta-amyloidosis correlate significantly with the stages of the neurofibrillary pathology proposed by Braak and Braak.

[Clinical aspects of "argyrophilic grain disease"]. / Klinische Aspekte der "argyrophilic grain disease".

Argyrophilic grain disease (AGD) is a frequently occurring degenerative illness of the aging human brain. It is accompanied by progressive pathological alterations of the cytsokeleton which are traceable to an abnormal phosphorylation of the microtubule associated tau protein. Histologically, it is possible with the help of suitable staining techniques to identify pathognomonic spindle-shaped cellular inclusions (argyrophilic grains). These cellular inclusions display a typical cortical as well as subcortical distribution pattern. The goal of the present study is the retrospective evaluation of the clinical findings from 53 individuals with neuropathologically demonstrable AGD-related changes of the brain. Nearly one-half of the cases (49%) was classifiable as demented in accordance with DSM IV-criteria. Moreover, the frequency of the dementia increased significantly in relation to the growing severity of the AGD-associated pathological cytoskeletal degeneration. These results confirm the assumption that AGD can cause degenerative changes ranging from cognitive impairment all the way to dementia. They also underscore the necessity of further prospective studies pertaining to the clinical aspects of this still enigmatic disease.

Sex-dependent cytoskeletal changes of the human hypothalamus develop independently of Alzheimer's disease.

This study examines a sex-dependent variant of neurofibrillary pathology recently identified in the hypothalamus of elderly human males. Here we focus upon the relationship between the sex-dependent hypothalamic changes and Alzheimer's disease (AD)-related neurofibrillary pathology. To this end, autopsy brains of 31 males (mean age 84.1 years) and 26 age-matched females (mean age 86.7 years) were examined. Both the male and the female subjects exhibited either particularly mild (stage I) or fully developed (stage V) AD-related neurofibrillary brain pathology. Serial 100-micron hypothalamic sections were cut in the frontal plane and stained for hyperphosphorylated tau protein using the monoclonal antibody AT8. Argyrophilic neurofibrillary pathology was demonstrated using a modified Gallyas silver-iodide technique. A conspicuous pathology, characterized by neurofibrillary tangles, a network of dystrophic neurites, and terminal-like vessel-associated processes, was identified in the infundibular nucleus which is located in the mediobasal tuber cinereum. This pathology was noted in 20 males (64.5%), but did not occur in the female group. No statistically significant correlation was noted between the degree of sex-dependent pathology and the presence of AD-related cortical pathology. In particular, the expression of the sex-dependent changes did not differ between males with AD stage I and males with AD stage V. In summary, the existence of a sex-dependent variant of neurofibrillary pathology was confirmed. In addition, our findings strongly suggest that the sex-dependent changes develop independently of the neurofibrillary changes associated with senile dementia of the Alzheimer type. Instead, the sex-dependent hypothalamic pathology probably corresponds to a distinct neurodegenerative entity preferentially affecting elderly males.

Argyrophilic grain disease is associated with apolipoprotein E epsilon 2 allele.

Argyrophilic grain disease (AGD) is a distinct degenerative disorder of the human brain associated with the formation of abnormally phosphorylated tau protein. AGD-related cytoskeletal changes are known to affect specific subsets of nerve cells and oligodendrocytes. Here we demonstrate a remarkable association between the apolipoprotein E (ApoE) epsilon2 allele and AGD. Individuals afflicted with AGD (n = 48) reveal a significantly higher frequency of the epsilon2 allele compared with controls (n = 43) (22% versus 4%, P < 0.0002). The association between AGD and epsilon2 allele of ApoE suggests that AGD can be distinguished from other neurodegenerative disorders not only neuropathologically, but also genetically.

High frequency of apolipoprotein E epsilon4 allele in young individuals with very mild Alzheimer's disease-related neurofibrillary changes.

The pathological process of initial neurofibrillary (NF) changes underlying Alzheimer's disease (AD) represents the early preclinical phase of the disease. In a small percentage of individuals, these initial NF changes (Braaks' stage I of six stages) may develop at a surprisingly young age. The aim of this study was to determine the impact of apolipoprotein E (ApoE) on the development of such initial NF changes in young individuals. To this end, the ApoE genotypes were determined using a seminested polymerase chain reaction assay followed by restriction isotyping in young individuals (n = 44; mean age of 38 years) with initial NF changes (stage I). The results were compared with ApoE genotypes of age-matched controls (n = 70) devoid of such changes (stage 0). Stage I cases exhibited a significantly higher epsilon4 allele frequency compared to controls (0.18 vs 0.09, P = 0.039). Thus, the present study reveals an association of epsilon4 allele with the early onset of AD-related NF changes in young individuals. This finding underlines the relevance of the asymptomatic phase in the course of AD.

Improved method facilitates reliable APOE genotyping of genomic DNA extracted from formaldehyde-fixed pathology specimens.

Apolipoprotein E (APOE) genotyping of genomic DNA extracted from formaldehyde-fixed specimens is cumbersome: there is not only a low yield or failure of PCR amplification (presumably due to degradation of DNA in the formaldehyde-fixed and paraffin-embedded tissue), but the standard method also involves the separation of DNA fragments as small as 48, 72, 81 and 91 bp requiring high-yield PCR products. Here we report about a semi-nested PCR method suitable for providing specific high-yield PCR products from DNA that has been extracted from formaldehyde-fixed specimens which initially generate low-quality templates. This method facilitates reliable APOE genotyping of DNA from difficult templates.

Neurofibrillary pathology in the human paraventricular and supraoptic nuclei.

Severe neurofibrillary changes were identified in the paraventricular and supraoptic nuclei of elderly individuals using markers for Alzheimer's disease-related intraneuronal pathology. This neurofibrillary pathology is remarkable in that the magnocellular paraventricular and supraoptic nuclei are particularly resistant to Alzheimer's disease. Moreover, the changes were observed even in non-demented controls, indicating that they develop independently of Alzheimer's disease. The alterations in the paraventricular and supraoptic nuclei were consistently accompanied by neurofibrillary changes in the mediobasal hypothalamus.

Optimization of restriction fragment length polymorphism and single strand conformation polymorphism analysis for the detection of point mutations of ras oncogenes in paraffin-embedded tissues.

69 samples of formalin-fixed and paraffin-embedded tumor tissues (colon carcinomas n = 15, colon adenomas n = 15, transitional cell carcinomas of the urinary bladder n = 17, transitional cell papillomas of the urinary bladder n = 22) were investigated for point mutations of ras oncogenes using polymerase chain reaction (PCR) and nested-PCR followed by restriction fragment length polymorphism (RFLP) and single strand conformation polymorphism (SSCP), respectively. Results were proved by sequence analysis. Nested-PCR combined with SSCP analysis revealed five mutations of the Ki-ras oncogenes in five colon tumors. RFLP analysis revealed one point mutation in one sample of invasive transitional cell carcinomas. Using optimized PCR protocols, the methods described are applicable to paraffin- embedded tissues and offer a tool for mutation analysis in retrospective and prospective studies.