Activation of the unfolded protein response in Parkinson’s disease

Parkinson's disease (PD) is, at the neuropathological level, characterized by the accumulation of misfolded proteins. The presence of misfolded proteins can trigger a cellular stress response in the endoplasmic reticulum (ER) called the Unfolded Protein Response (UPR). The UPR has been shown to be involved in cellular models for PD. In this study, we investigated UPR activation in the substantia nigra of control and PD patients. Immunoreactivity for the UPR activation markers phosphorylated pancreatic ER kinase (pPERK) and phosphorylated eukaryotic initiation factor 2alpha (peIF2alpha) is detected in neuromelanin containing dopaminergic neurons in the substantia nigra of PD cases but not in control cases. In addition, pPERK immunoreactivity is colocalized with increased alpha-synuclein immunoreactivity in dopaminergic neurons. These data show that the UPR is activated in PD and that UPR activation is closely associated with the accumulation and aggregation of alpha-synuclein.

Molecular misreading: the occurrence of frameshift proteins in different diseases

Neuronal homoeostasis requires a constant balance between biosynthetic and catabolic processes. Eukaryotic cells primarily use two distinct mechanisms for degradation: the proteasome and autophagy of aggregates by the lysosomes. We focused on the UPS (ubiquitin-proteasome system). As a result of molecular misreading, misframed UBB (ubiquitin B) (UBB+1) is generated. UBB+1 accumulates in the neuritic plaques and neurofibrillary tangles in all patients with AD (Alzheimer's disease) and in the neuronal and glial hallmarks of other tauopathies and in polyglutamine diseases such as Huntington's disease. UBB+1 is not present in synucleinopathies such as Parkinson's disease. We showed that UBB+1 causes UPS dysfunction, aggregation and apoptotic cell death. UBB+1 is also present in non-neurological cells, hepatocytes of the diseased liver and in muscles during inclusion body myositis. Other frequently occurring (age-related) diseases such as Type 2 (non-insulin-dependent) diabetes mellitus are currently under investigation. These findings point to the importance of the UPS in diseases and open new avenues for target identification of the main players of the UPS. Treatment of these diseases with tools (e.g. viral RNA interference constructs) to intervene with specific targets is the next step.

Degeneration of ingestion-related brainstem nuclei in spinocerebellar ataxia type 2, 3, 6 and 7

Dysphagia, which can lead to nutritional deficiencies, weight loss and dehydration, represents a risk factor for aspiration pneumonia. Although clinical studies have reported the occurrence of dysphagia in patients with spinocerebellar ataxia type 2 (SCA2), type 3 (SCA3), type 6 (SCA6) and type 7 (SCA7), there are neither detailed clinical records concerning the kind of ingestive malfunctions which contribute to dysphagia nor systematic pathoanatomical studies of brainstem regions involved in the ingestive process. In the present study we performed a systematic post mortem study on thick serial tissue sections through the ingestion-related brainstem nuclei of 12 dysphagic patients who suffered from clinically diagnosed and genetically confirmed spinocerebellar ataxias assigned to the CAG-repeat or polyglutamine diseases (two SCA2, seven SCA3, one SCA6 and two SCA7 patients) and evaluated their medical records. Upon pathoanatomical examination in all of the SCA2, SCA3, SCA6 and SCA7 patients, a widespread neurodegeneration of the brainstem nuclei involved in the ingestive process was found. The clinical records revealed that all of the SCA patients were diagnosed with progressive dysphagia and showed dysfunctions detrimental to the preparatory phase of the ingestive process, as well as the lingual, pharyngeal and oesophageal phases of swallowing. The vast majority of the SCA patients suffered from aspiration pneumonia, which was the most frequent cause of death in our sample. The findings of the present study suggest (i) that dysphagia in SCA2, SCA3, SCA6 and SCA7 patients may be associated with widespread neurodegeneration of ingestion-related brainstem nuclei; (ii) that dysphagic SCA2, SCA3, SCA6 and SCA7 patients may suffer from dysfunctions detrimental to all phases of the ingestive process; and (iii) that rehabilitative swallow therapy which takes specific functional consequences of the underlying brainstem lesions into account might be helpful in preventing aspiration pneumonia, weight loss and dehydration in SCA2, SCA3, SCA6 and SCA7 patients.

Neuronal intranuclear inclusions, dysregulation of cytokine expression and cell death in spinocerebellar ataxia type 3

OBJECTIVE

We analyzed the expression of the inflammatory mediators IL-1beta, IL-1ra, IL-6 and the transcription factors IRF-1 and C/EBPdelta (previously identified in a transgenic model of spinocerebellar ataxia type 3 (SCA3) by gene expression profiling) in the central nervous system of SCA3 patients in relation to neuronal cell loss and ataxin-3-positive neuronal intranuclear inclusions (NI), to identify a putative upregulation of cytokines or microglia in SCA3 brains and to investigate whether enhanced cytokine expression was a generalized event mediating neuronal dysfunction in SCA3.

MATERIALS AND METHODS

Light- and electronmicroscopic immunohistochemistry was performed on SCA3 tissues derived from five patients from unrelated families with genetically confirmed diagnosis, and six individuals without a history of neurological or inflammatory disease.

RESULTS

NI were found almost exclusively in brain regions that also showed neuronal cell loss, i.e. in pons and dentate nucleus neurons, rarely in putamen and thalamus, but not in cerebral or cerebellar cortex. NI displayed an irregular surface and were mostly attached to the nucleoli. Quantitative analysis of NI in the pons revealed an inverse relation of NI and cell loss, i.e. patients with more severe neuronal cell loss had a smaller proportion of neurons with NI. Thus, formation of NI is not necessarily an indicator of cell death but could exert a protective effect. We found increased expression of IL-1beta, IL-1ra, IL-6 and C/EBPdelta only in pons and dentate nucleus neurons and both in neurons with and without NI, suggesting that NI are not a prerequisite for transcriptional changes.

CONCLUSIONS

Our data suggest that the selectively affected neuronal populations in SCA3 undergo a complex alteration of gene expression independent from the formation of NI.

Frameshift proteins in autosomal dominant forms of Alzheimer disease and other tauopathies

Frameshift (+1) proteins such as APP(+1) and UBB(+1) accumulate in sporadic cases of Alzheimer disease (AD) and in older subjects with Down syndrome (DS). We investigated whether these proteins also accumulate at an early stage of neuropathogenesis in young DS individuals without neuropathology and in early-onset familial forms of AD (FAD), as well as in other tauopathies, such as Pick disease (PiD) or progressive supranuclear palsy (PSP). APP(+1) is present in many neurons and beaded neurites in very young cases of DS, which suggests that it is axonally transported. In older DS patients (>37 years), a mixed pattern of APP(+1) immunoreactivity was observed in healthy looking neurons and neurites, dystrophic neurites, in association with neuritic plaques, as well as neurofibrillary tangles. UBB(+1) immunoreactivity was exclusively present in AD type of neuropathology. A similar pattern of APP(+1) and UBB(+1) immunoreactivity was also observed for FAD and much less explicit in nondemented controls after the age of 51 years. Furthermore, we observed accumulation of +1 proteins in other types of tauopathies, such as PiD, frontotemporal dementia, PSP and argyrophylic grain disease. These data suggest that accumulation of +1 proteins contributes to the early stages of dementia and plays a pathogenic role in a number of diseases that involve the accumulation of tau.

Spinocerebellar ataxia type 7 (SCA7): first report of a systematic neuropathological study of the brain of a patient with a very short expanded CAG-repeat

Spinocerebellar ataxia type 7 (SCA7) represents a very rare and severe autosomal dominantly inherited cerebellar ataxia (ADCA). It belongs to the group of CAG-repeat or polyglutamine diseases with its underlying molecular genetical defect on chromosome 3p12-p21.1. Here, we performed a systematic study of the neuropathology on unconventional thick serial sections of the first available brain tissue of a genetically confirmed late-onset SCA7 patient with a very short CAG-repeat expansion. Along with myelin pallor of a variety of central nervous fiber tracts, we observed i) neurodegeneration in select areas of the cerebral cortex, and ii) widespread nerve cell loss in the cerebellum, thalamus, nuclei of the basal ganglia, and brainstem. In addition, upon immunocytochemical analysis using the anti-polyglutamine antibody 1C2, immunopositive neuronal intranuclear inclusions bodies (NI) were observed in all cerebellar regions, in all parts of the cerebral cortex, and in telencephalic and brainstem nuclei, irrespective of whether they underwent neurodegeneration. These novel findings provide explanations for a variety of clinical symptoms and paraclinical findings of both our and other SCA7 patients. Finally, our immunocytochemical analysis confirms previous studies which described the presence of NI in obviously degenerated brain and retinal regions as well as in apparently well-preserved brain regions and retina of SCA7 patients.

Pathology associated with sporadic Parkinson's disease--where does it end?

Parkinson's disease (PD) is a multisystem disorder in which predisposed neuronal types in specific regions of the human peripheral, enteric, and central nervous systems become progressively involved. A staging procedure for the PD-related inclusion body pathology (i.e., Lewy neurites and Lewy bodies) in the brain proposes that the pathological process begins at two sites and progresses in a topographically predictable sequence in 6 stages. During stages 1-2, the inclusion body pathology remains confined to the medulla oblongata, pontine tegmentum, and anterior olfactory structures. In stages 3-4, the basal mid- and forebrain become the focus of the pathology and the illness reaches its symptomatic phase. In the final stages 5-6, the pathological process is seen in the association areas and primary fields of the neocortex. To date, we have staged a total of 301 autopsy cases, including 106 cases with incidental pathology and 176 clinically diagnosed PD cases. In addition, 163 age-matched controls were examined. 19 of the 301 cases with PD-related pathology displayed a pathological distribution pattern of Lewy neurites and Lewy bodies that diverged from the staging scheme described above. In these cases, olfactory structures and the amygdala were predominantly involved in the virtual absence of brain stem pathology. Most of the divergent cases (17/19) had advanced concomitant Alzheimer's disease-related neurofibrillary changes (stages IV-VI).

Spinocerebellar ataxia type 4 (SCA4): Initial pathoanatomical study reveals widespread cerebellar and brainstem degeneration

Spinocerebellar ataxia type 4 (SCA4), also known as 'hereditary ataxia with sensory neuropathy', represents a very rare, progressive and untreatable form of an autosomal dominant inherited cerebellar ataxia (ADCA). Due to a lack of autopsy cases, no neuropathological or clinicopathological studies had yet been performed in SCA4. In the present study, the first available cerebellar and brainstem tissue of a clinically diagnosed and genetically-confirmed German SCA4 patient was pathoanatomically studied using serial thick sections. During this systematic postmortem investigation, along with an obvious demyelinization of cerebellar and brainstem fiber tracts we observed widespread cerebellar and brainstem neurodegeneration with marked neuronal loss in the substantia nigra and ventral tegmental area, central raphe and pontine nuclei, all auditory brainstem nuclei, in the abducens, principal trigeminal, spinal trigeminal, facial, superior vestibular, medial vestibular, interstitial vestibular, dorsal motor vagal, hypoglossal, and prepositus hypoglossal nuclei, as well as in the nucleus raphe interpositus, all dorsal column nuclei, and in the principal and medial subnuclei of the inferior olive. Severe neuronal loss was seen in the Purkinje cell layer of the cerebellum, in the cerebellar fastigial nucleus, in the red, trochlear, lateral vestibular, and lateral reticular nuclei, the reticulotegmental nucleus of the pons, and the nucleus of Roller. In addition, immunocytochemical analysis using the anti-polyglutamine antibody 1C2 failed to detect any polyglutamine-related immunoreactivity in the central nervous regions of this SCA4 patient studied. In view of the known functional role of affected nuclei and related fiber tracts, the present findings not only offer explanations for the well-known disease symptoms of SCA4 patients (i.e. ataxic symptoms, dysarthria and somatosensory deficits), but for the first time help to explain why diplopia, gaze-evoked nystagmus, auditory impairments and pathologically altered brainstem auditory evoked potentials, saccadic smooth pursuits, impaired somatosensory functions in the face, and dysphagia may occur during the course of SCA4. Finally, the results of our immunocytochemical studies support the concept that SCA4 is not a member of the CAG-repeat or polyglutamine diseases.

Involvement of the cranial nerves and their nuclei in spinocerebellar ataxia type 2 (SCA2)

Although the cranial nerves, their nuclei and related fiber tracts are crucial for a variety of oculomotor, somatomotor, somatosensory, auditory, vestibular-related, autonomic and ingestion-related functions, knowledge regarding the extent of their involvement in spinocerebellar ataxia type 2 (SCA2) patients is incomplete. Accordingly, we performed a pathoanatomical analysis of these structures in six clinically diagnosed SCA2 patients. Unconventionally thick serial sections through the brainstem stained for lipofuscin pigment (aldehyde-fuchsin) and Nissl material (Darrow red) showed that all oculomotor, somatomotor, somatosensory, auditory, vestibular and autonomic cranial nerve nuclei may undergo neurodegeneration during SCA2. Similarly, examination of myelin-stained thick serial sections revealed that nearly all cranial nerves and associated fiber tracts may sustain atrophy and myelin loss in SCA2 patients. In view of the known functional role of the affected cranial nerves, their nuclei and associated fiber tracts, the present findings provide appropriate pathoanatomical explanations for some of the disease-related and unexplained symptoms seen in SCA2 patients: double vision, gaze palsy, slowing of saccades, ptosis, ingestion-related malfunctions, impairments of the optokinetic nystagmus and the vestibulo-ocular reaction, facial and tongue fasciculation-like movements, impaired centripetal transmission of temperature-related information from the face, dystonic posture of the neck, as well as abnormalities of the brainstem auditory evoked potentials.

'Spontaneous' cholesterol embolisation syndrome after successful prehospital thrombolysis for acute myocardial infarction

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Cognitive status correlates with neuropathologic stage in Parkinson disease

OBJECTIVE

To study the association of cognitive status with the stages of a published neuropathologic staging procedure for sporadic Parkinson disease (PD) in a cohort of 88 patients with PD from a single neurologic unit. None had received the clinical diagnosis of dementia with Lewy bodies (DLB).

METHODS

The authors assessed Lewy neurites/bodies (LNs/LBs) immunoreactive for alpha-synuclein semiquantitatively in sections from 18 brain regions. In silver-stained sections and sections immunostained for tau and beta-amyloid protein, the authors semiquantitatively evaluated comorbidities potentially contributing to cognitive decline, e.g., Alzheimer disease (AD), argyrophilic grain disease (AGD), and cerebral vascular disease. The authors analyzed four Mini-Mental State Examination (MMSE) subgroups ranging from marginally impaired cognition to severe dementia using nonparametric tests.

RESULTS

It was possible to assign all patients to one of the PD stages. MMSE scores correlated with neuropathologic stages (p < 0.005) and this association showed a linear trend (p < 0.025). Median MMSE test scores for women were lower than those for men. Cognitively impaired individuals displayed higher stages of AD-related neurofibrillary pathology (p < 0.05) and beta-amyloid deposition (p < 0.05) than cognitively unimpaired persons. MMSE scores did not correlate significantly with AGD, disease duration, age at disease onset, or age at death. Hoehn and Yahr scores, however, correlated with PD stages (p < 0.0005) and MMSE scores (p < 0.0005).

CONCLUSIONS

The decrease in median Mini-Mental State Examination scores between PD stages 3 to 6 indicates that the risk of developing dementia increases with disease progression. In some individuals, however, cognitive decline can develop in the presence of mild Parkinson disease-related cortical pathology and, conversely, widespread cortical lesions do not necessarily lead to cognitive decline.

Spinocerebellar ataxias types 2 and 3: degeneration of the pre-cerebellar nuclei isolates the three phylogenetically defined regions of the cerebellum

The pre-cerebellar nuclei act as a gate for the entire neocortical, brainstem and spinal cord afferent input destined for the cerebellum. Since no pathoanatomical studies of these nuclei had yet been performed in spinocerebellar ataxia type 2 (SCA2) or type 3 (SCA3), we carried out a detailed postmortem study of the pre-cerebellar nuclei in six SCA2 and seven SCA3 patients in order to further characterize the extent of brainstem degeneration in these ataxic disorders. By means of unconventionally thick serial sections through the brainstem stained for lipofuscin pigment and Nissl material, we could show that all of the pre-cerebellar nuclei (red, pontine, arcuate, prepositus hypoglossal, superior vestibular, lateral vestibular, medial vestibular, interstitial vestibular, spinal vestibular, vermiform, lateral reticular, external cuneate, subventricular, paramedian reticular, intercalate, interfascicular hypoglossal, and conterminal nuclei, pontobulbar body, reticulotegmental nucleus of the pons, inferior olive, and nucleus of Roller) are among the targets of both of the degenerative processes underlying SCA2 and SCA3. These novel findings are in contrast to the current neuropathological literature, which assumes that only a subset of pre-cerebellar nuclei in SCA2 and SCA3 may undergo neurodegeneration. Widespread damage to the pre-cerebellar nuclei separates all three phylogenetically and functionally defined regions of the cerebellum, impairs their physiological functions and thus explains the occurrence of gait, stance, limb and truncal ataxia, dysarthria, truncal and postural instability with disequilibrium, impairments of the vestibulo-ocular reaction and optokinetic nystagmus, slowed and saccadic smooth pursuits, dysmetrical horizontal saccades, and gaze-evoked nystagmus during SCA2 and SCA3.

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.

Expression of NAD(P)H:quinone oxidoreductase in the normal and Parkinsonian substantia nigra

Dopamine (DA) autooxidation, and consequent formation of neurotoxic DA-derived quinones and reactive oxygen species, has been implicated in dopaminergic cell death and, hence, in the pathogenesis of Parkinson's disease (PD). Stimulation of pathways involved in the detoxication of DA-quinones in the brain is hypothesized to be an effective means to limit oxidative stress and to confer neuroprotection in PD. In this respect, the inducible flavoprotein NAD(P)H:quinone oxidoreductase (NQO1) is of particular interest as it is directly implicated in the detoxication of DA-quinones and, in addition, has broad spectrum anti-oxidant properties. To study the potential pathophysiological role of NQO1 in PD, the cellular expression of NQO1 was examined in the mesencephalon of PD patients and age-matched controls. In the substantia nigra pars compacta (SNpc), NQO1 was found to be expressed in astroglial and endothelial cells and, albeit less frequently, also in dopaminergic neurons. Moreover, while overt NQO1 immunoreactivity was absent in the surrounding nervous tissue, in the Parkinsonian SNpc a marked increase in the astroglial and neuronal expression of NQO1 was consistently observed.

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.

Anatomically based guidelines for systematic investigation of the central somatosensory system and their application to a spinocerebellar ataxia type 2 (SCA2) patient

Dysfunctions of the somatosensory system are among the clinical signs that characterize a variety of polyglutamine or CAG-repeat diseases. Deficits within this system may hinder the perception of potential threats, be detrimental to somatomotor functions, and result in uncoordinated movements, ataxia, and falls. Despite the considerable clinical relevance of such deficits, however, no systematic pathoanatomical studies of the central somatosensory system in polyglutamine diseases are currently available. The present paper has two goals: (1) recommendation of an economical tissue sampling method and optimized histological processing of this tissue to allow rapid and reliable evaluation of the structural integrity of all known relay stations and interconnecting fibre tracts within this complex system, and (2) the proposal of guidelines for a rapid and detailed pathoanatomical investigative procedure of the human central somatosensory system. In so doing, we draw on the current state of neuroanatomic research and apply the methods and guidelines proposed here to a 25-year-old female patient with spinocerebellar ataxia type 2 (SCA2). The use of 100 microm serial sections through the SCA2 patient's central somatosensory components showed that obvious neuronal loss occurred in nearly all of the relay stations of this system (Clarke's column; cuneate, external cuneate and gracile nuclei; spinal, principal and mesencephalic trigeminal nuclei; ventral posterior lateral and ventral posterior medial nuclei of the thalamus), whereas the majority of interconnecting fibre tracts (dorsal spinocerebellar tract; cuneate and gracile fascicles; medial lemniscus; spinal trigeminal tract, trigeminal nerve and mesencephalic trigeminal tract) displayed signs of atrophy accompanied by demyelinization. These pathological findings suffice to explain the patient's impaired senses of vibration, position and temperature. Moreover, together with the lesions seen in the motor cerebellothalamocortical feedback loop (pontine nuclei, deep cerebellar nuclei and cerebellar cortex, ventral lateral nucleus of the thalamus), they also account for the somatomotor deficits that were observed in the young woman (gait, stance, and limb ataxia, falls, and impaired writing). In proposing these new guidelines, we hope to enable others to study the hitherto unknown morphological counterparts of somatosensory dysfunctions in additional CAG-repeat disease patients.

Thalamic involvement in a spinocerebellar ataxia type 2 (SCA2) and a spinocerebellar ataxia type 3 (SCA3) patient, and its clinical relevance

In spite of the considerable progress in clinical and molecular research, knowledge regarding brain damage in spinocerebellar ataxia type 2 (SCA2) and type 3 (SCA3) still is limited and the extent to which the thalamus is involved in both diseases is uncertain. Accordingly, we performed a pathoanatomical analysis on serial thick sections stained for lipofuscin granules and Nissl substance through the thalami of two genetically confirmed cases: one an SCA2 patient, the other an SCA3 patient. During this systematic study, we detected severe destruction of the reticular (RT), fasciculosus (FA), ventral anterior (VA), ventral lateral (VL), ventral posterior lateral (VPL), ventral posterior medial (VPM), cucullar (CU) and mediodorsal thalamic nuclei (MD), the lateral geniculate body (LGB) and inferior nucleus of the pulvinar (PU i) in the SCA2 case, and a severe neuronal loss in the RT, FA, VA and PU i of the SCA3 case. In the SCA2 patient, additional obvious neuronal loss was observed in all nuclei of the anterior and rostral intra laminar groups, in the lateral posterior nucleus (LP), the lateral (PU l) and the medial subnuclei of the pulvinar (PU m), whereas in the SCA3 patient only two of the nuclei that belong to the anterior thalamic group, the VL, VPL, VPM, LP, LGB, PU l and PU m, displayed marked neurodegeneration. These novel findings indicate that thalamic involvement in SCA2 and SCA3 patients has been underestimated in the past. In view of what is known about the functions of the affected thalamic nuclei, the present findings provide an appropriate pathoanatomical explanation for some of the disease-related symptoms seen in both of our and other SCA2 and SCA3 patients: gait, stance, truncal and limb ataxia, dysarthria or anarthria, falls, dysdiadochokinesia and bradykinesia, problems with writing, somatosensory deficits, saccadic dysfunctions, executive dysfunctions and abnormalities of visual evoked potentials.

The nucleus raphe interpositus in spinocerebellar ataxia type 3 (Machado-Joseph disease)

The nucleus raphe interpositus (RIP) plays an important role in the premotor network for saccades. Its omnipause neurons gate the activity of the burst neurons for vertical saccades lying within the rostral interstitial nucleus of the medial longitudinal fascicle and that for horizontal saccades residing in the caudal subnucleus of the pontine reticular formation. In the present study we investigated the RIP in five patients with clinically diagnosed and genetically confirmed spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease. Polyethylene glycol-embedded 100 microm serial sections stained for lipofuscin pigment and Nissl material as well as paraffin-embedded Nissl stained thin sections revealed the hitherto overlooked involvement of this pontine nucleus in the degenerative process underlying SCA3, whereby in four of our SCA3 patients the RIP underwent a conspicuous loss of presumed omnipause neurons. As observed in other affected brain structures, the RIP of all our SCA3 patients displayed reactive astrocytes and activated microglial cells, while some of the few of its surviving neurons harbored an ataxin-3-immunopositive intranuclear inclusion body. The findings of the present pathoanatomical study suggest that (1) neurodegeneration in the brain stem of terminal SCA3 patients is more widespread than previously thought and is not confined to cranial nerve nuclei involved in the generation of saccades but likewise involves the premotor network for saccades and (2) damage to the RIP may contribute to slowing of horizontal saccades in SCA3 patients but is not associated with saccadic oscillations as occasionally speculated.

Guidelines for the pathoanatomical examination of the lower brain stem in ingestive and swallowing disorders and its application to a dysphagic spinocerebellar ataxia type 3 patient

Despite the fact that considerable progress has been made in the last 20 years regarding the three-phase process of ingestion and the lower brain stem nuclei involved in it, no comprehensive descriptions of the ingestion-related lower brain stem nuclei are available for neuropathologists confronted with ingestive malfunctions. Here, we propose guidelines for the pathoanatomical investigation of these nuclei based on current knowledge with respect to ingestion and the nuclei responsible for this process. The application of these guidelines is described by drawing upon the example of the lower brain stem of a male patient with spinocerebellar ataxia type 3, also known as Machado-Joseph disease, who displayed malfunctions during the preparatory phase of ingestion, as well as lingual and pharyngeal phases of swallowing. By way of the representative application of the recommended investigation procedure to 100 microm serial sections through the patient's brain stem stained for lipofuscin pigment and Nissl material, we observed neuronal loss together with astrogliosis in nearly all of the ingestion-related lower brain stem nuclei (motor, principal and spinal trigeminal nuclei; facial nucleus; parvocellular reticular nucleus; ambiguous nucleus, motor nucleus of the dorsal glossopharyngeal and vagal area; gelatinous, medial, parvocellular and pigmented solitary nuclei; hypoglossal nucleus). In view of their known functional role in the three-phase process of ingestion, damage to these nuclei not only offers an explanation of the patient's malfunctions related to the preparatory phase of ingestion and lingual and pharyngeal phases of swallowing, but also suggests that the patient may have suffered from additional esophageal phase swallowing malfunctions not mentioned in his medical records.

Degeneration of the external cuneate nucleus in spinocerebellar ataxia type 3 (Machado-Joseph disease)

Owing to its anatomical connections, the external cuneate nucleus (ECU) plays a crucial role in processing proprioceptive input from the upper trunk and upper limbs. Here, we studied this dorsal column nucleus post-mortem in five individuals with clinically diagnosed and genetically confirmed spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease, who had manifested upper trunk and upper limb ataxia. Polyethylene glycol-embedded 100-microm sections stained for lipofuscin pigment and Nissl material, as well as paraffin-embedded Nissl-stained thin sections, revealed serious neuronal loss in the ECU of all five SCA3 patients. As observed in other affected central nervous system structures, the ECU of these individuals displayed an astrogliosis, and some of the few surviving neurons harbored one or even two ataxin-3-immunopositive intranuclear inclusion bodies. The findings of the present study suggest that (1) the ECU is among the consistent targets of the degenerative process underlying SCA3 and (2) interruption of the proprioceptive pathway at the level of the ECU contributes significantly to upper limb and trunk ataxia in SCA3 patients.

Spinocerebellar ataxia type 3 (Machado-Joseph disease): severe destruction of the lateral reticular nucleus

The lateral reticular nucleus (LRT) of the medulla oblongata is a precerebellar nucleus involved in proprioception and somatomotor automatisms. We investigated this nucleus in five individuals with clinically diagnosed and genetically confirmed spinocerebellar ataxia type 3 (SCA3, Machado-Joseph disease). Polyethylene glycol-embedded 100 micro m thick sections stained for lipofuscin granules and Nissl material as well as Nissl-stained paraffin-embedded sections revealed severe destruction of the LRT in all SCA3 brains examined. Some of the few surviving neurones contained ataxin-3-immunopositive intranuclear inclusion bodies, as noted in other affected brain regions in SCA3. Along with the severe neuronal depletion, obvious astrogliosis was seen in the LRT of all SCA3 patients. The findings suggest that the LRT is a consistent target of the pathological process underlying SCA3. In view of its afferent and efferent connections, destruction of the LRT probably contributes to gait ataxia in individuals suffering from SCA3.

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.

Progressive supranuclear palsy: neuronal and glial cytoskeletal pathology in the higher order processing autonomic nuclei of the lower brainstem

The medial and lateral parabrachial nuclei (MPB, LPB), the gigantocellular reticular nucleus (GI), the raphes magnus (RMG) and raphes obscurus nuclei (ROB), as well as the intermediate reticular zone (IRZ) represent pivotal subordinate brainstem centres, all of which control autonomic functions. In this study, we investigated the occurrence and severity of the neuronal and glial cytoskeletal pathology in these six brainstem nuclei from 17 individuals with clinically diagnosed and neuropathologically confirmed progressive supranuclear palsy (PSP). The association between the severity of the pathology and the duration of the disease was investigated by means of correlation analysis. The brainstem nuclei in all of the PSP cases were affected by the neuronal cytoskeletal pathology, with the IRZ and GI regularly showing severe involvement, the MPB, RMG, and ROB marked involvement, and the LPB mild involvement. In the six nuclear greys studied, glial cells undergo alterations of their cytoskeleton on an irregular basis, whereby diseased oligodendrocytes predominantly presented as coiled bodies and affected astrocytes as thorn-shaped astrocytes. In all six nuclei, the severity of the neuronal or glial cytoskeletal pathology showed no correlation with the duration of PSP. In view of their functional role, the neuronal pathology in the nuclei studied offers a possible explanation for the autonomic dysfunctions that eventually develop in the course of PSP.