Neurofilament subunit--related proteins in neuronal intranuclear inclusions

The role of neurofilament aggregation in neurodegeneration: lessons from rare inherited neurological disorders

Many neurodegenerative disorders, including Parkinson's, Alzheimer's, and amyotrophic lateral sclerosis, are well known to involve the accumulation of disease-specific proteins. Less well known are the accumulations of another set of proteins, neuronal intermediate filaments (NFs), which have been observed in these diseases for decades. NFs belong to the family of cytoskeletal intermediate filament proteins (IFs) that give cells their shape; they determine axonal caliber, which controls signal conduction; and they regulate the transport of synaptic vesicles and modulate synaptic plasticity by binding to neurotransmitter receptors. In the last two decades, a number of rare disorders caused by mutations in genes that encode NFs or regulate their metabolism have been discovered. These less prevalent disorders are providing novel insights into the role of NF aggregation in the more common neurological disorders.

Neuropathophysiology of functional gastrointestinal disorders

The investigative evidence and emerging concepts in neurogastroenterology implicate dysfunctions at the levels of the enteric and central nervous systems as underlying causes of the prominent symptoms of many of the functional gastrointestinal disorders. Neurogastroenterological research aims for improved understanding of the physiology and pathophysiology of the digestive subsystems from which the arrays of functional symptoms emerge. The key subsystems for defecation-related symptoms and visceral hyper-sensitivity are the intestinal secretory glands, the musculature and the nervous system that controls and integrates their activity. Abdominal pain and discomfort arising from these systems adds the dimension of sensory neurophysiology. This review details current concepts for the underlying pathophysiology in terms of the physiology of intestinal secretion, motility, nervous control, sensing function, immuno-neural communication and the brain-gut axis.

Human enteric neuropathies: morphology and molecular pathology

The aim of this study is to review current understanding of the molecular and morphological pathology of the enteric neuropathies affecting motor function of the human gastrointestinal tract and to evaluate the described pathological entities in the literature to assess whether a new nosology may be proposed. The authors used PUBMED and MEDLINE searches to explore the literature pertinent to the molecular events and pathology of gastrointestinal motility disorders including achalasia, gastroparesis, intestinal pseudo-obstruction, colonic inertia and megacolon in order to characterize the disorders attributable to enteric gut neuropathies. This scholarly review has shown that the pathological features are not readily associated with clinical features, making it difficult for a patient to be classified into any specific category. Individual patients may manifest more than one of the morphological and molecular abnormalities that include: aganglionosis, neuronal intranuclear inclusions and apoptosis, neural degeneration, intestinal neuronal dysplasia, neuronal hyperplasia and ganglioneuromas, mitochondrial dysfunction (syndromic and non-syndromic), inflammatory neuropathies (caused by cellular or humoral immune mechanisms), neurotransmitter diseases and interstitial cell pathology. The pathology of enteric neuropathies requires further study before an effective nosology can be proposed. Carefully studied individual cases and small series provide the basic framework for standardizing the collection and histological evaluation of tissue obtained from such patients. Combined clinical and histopathological studies may facilitate the translation of basic science to the clinical management of patients with enteric neuropathies.

Neuropathophysiology of irritable bowel syndrome

Widespread symptoms associated with the irritable bowel syndrome (IBS) are abnormal defecation and abdominal pain, both of which can be exacerbated by psychogenic stress. Disordered defecation may present as diarrhea or constipation. A subgroup of IBS patients alternate from one to the other over time. Urgency to stool often accompanies the diarrheal-state, and patients with the constipation-predominant form of IBS report straining and the feeling of incomplete evacuation. Basic scientific research aims for improved understanding of the physiology and pathophysiology of the digestive systems from which the arrays of IBS symptoms emerge. The key systems for the defecation-related symptoms are the intestinal secretory glands, the musculature, and the nervous system that controls and integrates their activity. Abdominal pain and discomfort arising from these systems adds the dimension of sensory neurophysiology. This review details current concepts of the underlying pathophysiology in terms of the physiology of intestinal secretion, motility, nervous control, sensing function, immuno-neural communication, and the brain-gut axis.

Familial neuronal intranuclear inclusion disease with ubiquitin positive inclusions

Female monozygotic twins developed upper and lower limb neurogenic weakness in their thirties, followed by cerebellar ataxia, dysarthria and death after an illness duration of about 20 years. Autopsy revealed pathological features typical of neuronal intranuclear inclusion disease (NIID) and positive ubiquitin immunostaining of the inclusions. Two adult sons of one of the twins have now developed an identical illness. This family provides strong evidence of an hereditary form of NIID.

Intranuclear inclusions of expanded polyglutamine protein in spinocerebellar ataxia type 3

The mechanism of neurodegeneration in CAG/polyglutamine repeat expansion diseases is unknown but is thought to occur at the protein level. Here, in studies of spinocerebellar ataxia type 3, also known as Machado-Joseph disease (SCA3/MJD), we show that the disease protein ataxin-3 accumulates in ubiquitinated intranuclear inclusions selectively in neurons of affected brain regions. We further provide evidence in vitro for a model of disease in which an expanded polyglutamine-containing fragment recruits full-length protein into insoluble aggregates. Together with recent findings from transgenic models, our results suggest that intranuclear aggregation of the expanded protein is a unifying feature of CAG/polyglutamine diseases and may be initiated or catalyzed by a glutamine-containing fragment of the disease protein.

Neuronal intranuclear inclusion disease: polymerase chain reaction and ultrastructural study of rectal biopsy specimen in a new case

We report the case of a boy with neuronal intranuclear inclusion disease in whom the diagnosis was made by examination of a rectal biopsy specimen. Intranuclear inclusions were observed in the Auerbach and Meissner plexuses. In an attempt to understand the physiopathology of this very rare disease, we performed polymerase chain reaction (PCR) and reverse transcriptase-PCR analysis for viral nucleic acids of human immunodeficiency virus type 1 (HIV-1), HIV-2, human cytomegalovirus and measles virus. No viral nucleic acids were detected in the biopsy specimen.

Generalised nuclear and cytoplasmic inclusion disease: a rare case investigated by microscopy and immunohistochemistry

A Caucasian female who was noted to be mildly microcephalic at birth was diagnosed as having cerebral palsy at the age of 1 year. Her development was delayed and she never walked or talked. She appeared relatively stable neurologically until the age of 17 years when she had an illness with fever thought to be due to a virus. She was noted to deteriorate from this time on until her death at the age of 19 years. Autopsy revealed intranuclear and cytoplasmic inclusions wide-spread throughout the brain and visceral organs. There was no evidence of inflammation. Immunohistochemistry revealed strong immunoreactivity for tau protein and neurofilament protein. Electron microscopy revealed the inclusions to be composed of homogeneous finely granular material. Scattered within the granular material in the cytoplasmic bodies were crystalline structures with a honeycomb appearance. The possibility of these changes representing an old viral infection or a primary metabolic disorder are discussed.

Demyelinative process associated with atypical intranuclear glial inclusions

This case study documents a demyelinating process associated with atypical glial intranuclear inclusions. The patient, a 38-year-old woman, presented with acute onset of headaches and weakness. Magnetic resonance imaging revealed two discrete intrahemispheric lesions. Light microscopic examination showed small, homogeneous, eosinophilic inclusions chiefly in astroglial nuclei. By electron microscopy these inclusions were shown to be clusters of filamentous structures. Attempts to identify the particles with an antibody to measles virus and in situ hybridization to JC virus were negative. The morphologic appearance of the inclusions in this case is similar to that described in neuronal intranuclear inclusion disease.

Paired helical filaments and the cytoplasmic-nuclear interface in Alzheimer's disease

The cytoplasmic-nuclear interface has been investigated by conventional thin sectioning electron microscopy of neurons from frontal lobe biopsies of 13 patients with Alzheimer's disease. Nine patients were in the early and intermediate stages of the disease and four patients in the advanced stage. Fascicles of paired helical filament-like strands and paired helical filaments appose the nuclear envelope, the nuclear pore complexes and the perinuclear polysomes. Paired helical filament profiles have also been identified in the nucleoplasm. These observations indicate that the cytoplasmic-nuclear interface and, consequently, the relationships between the cytoplasm and the nucleus, might be impaired in Alzheimer's disease.

Pathology of neuromuscular disorders of the small intestine and colon

A variety of pathological abnormalities of the smooth muscle and myenteric plexus result in clinical syndromes of disordered small intestinal and colonic motility. These pathological abnormalities have been noted by conventional light microscopy and by utilization of Smith's technique for visualizing the myenteric plexus with silver. We have classified the neuromuscular disorders into two major categories, i.e., those affecting the myenteric plexus and those affecting the smooth muscle. The classification is further developed based on the variety of clinicopathological features of the various disorders. Although we can now identify the underlying pathology of these motor disorders and thus understand these illnesses better than we did a decade ago, we have much more to learn. With the great strides being made to understand the normal structure, function, and development of the myenteric plexus and smooth muscle, there is hope that we will be able to learn much more about the etiology and pathogenesis of these neuromuscular disorders in the decade to come.

Neuronal intranuclear inclusion disease. Clinical ophthalmological features and ophthalmic pathology

Monozygotic twin sisters were afflicted by a chronic progressive neurological disease characterized by slurred speech, nystagmus and oculogyral spasms as well as further extrapyramidal and lower motor neuron abnormalities. At autopsy severe loss of nigral and craniospinal motor neurons was noted. In the nuclei of most nerve cell types of the central and peripheral nervous system, roundish inclusion bodies of 3 to 10 microns in diameter were found. Ocular pathology revealed the presence of identical inclusion bodies in the ganglion cells and ganglion cell loss in the posterior retina. Retinal astrocytosis and loss of myelinated axons of the optic nerve were interpreted as reactive features. No inclusions were found in the retinal pigment epithelium. Careful neuro-ophthalmological studies of the first-degree relatives revealed low b-wave of the ERG with other slight aberrations. These were assumed to represent either a carrier or a subclinical state of this presumably inherited disorder.

Clinicopathological studies of some non-Alzheimer dementing diseases

The brains of most demented patients show at autopsy the lesions of Alzheimer's disease (AD). However, the brains of other demented patients show either no morphological changes or lesions distinct from those of AD. We report clinicopathological studies on two diseases in this latter group. The study of these diseases can improve our understanding of AD. Pick's disease is characterized by dementia, lobar cerebral atrophy, and neuronal cytoplasmic inclusions. Most cases, which we have called "classical", show inclusions made up of straight fibrils that are immunologically cross-reactive with the paired helical filaments of AD. In other "generalized" cases, similar fibrils are coated by granular material and are less reactive with anticytoskeletal antibodies. In contrast to the cytoplasmic localization of the lesions in Pick's disease, it is the cell nucleus that shows abnormalities in neuronal intranuclear hyaline inclusion disease. This disease can present clinically as dementia of adult onset. Thus, either nuclear or cytoplasmic lesions can produce a pattern of neuronal dysfunction resulting in dementia.

Cytoskeletal protein abnormalities in neurodegenerative diseases

The nervous system is a rich source of filamentous proteins that assume critical roles in determining and maintaining neuronal form and function. Neurons contain three major classes of these cytoskeletal organelles: microtubules, intermediate filaments, and microfilaments. They also contain a variety of proteins that organize them and serve to connect them with each other. Such major neurodegenerative diseases as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as a variety of toxic neuropathies, are characterized pathologically by intraneuronal filamentous inclusions. Recent studies using biochemical and immunocytochemical techniques have established that these abnormalities represent disorganized states of the neuronal cytoskeleton and have determined some of the specific molecular constituents of these inclusions. This knowledge has led to new ways of thinking about their origins.

Neuronal intranuclear hyaline inclusion disease in a nine year old

Thirteen previous cases have been reported as neuronal intranuclear hyaline inclusion disease. The majority of patients have presented with movement disorders at less than 12 years of age followed by a progressive worsening of symptoms and, frequently, loss of cognitive function. Death has usually occurred by the second or third decade. Three have presented in the fifth through seventh decade with either movement disorders or dementia. These cases have been linked by the presence of eosinophilic neuronal intranuclear inclusions diffusely within the CNS and in peripheral ganglion cells. The patient in this case report also presented with a rapidly progressive movement disorder and at autopsy showed the characteristic intranuclear inclusions. Investigation of these inclusions did not reveal shared epitopes with neurofilaments or other intermediate filaments.

Neuronal intranuclear inclusion disease in identical twins

A pair of female identical twins exhibited slurred speech, nystagmus, and oculogyral spasms starting at age 11. The patients then had episodic rage, extrapyramidal and lower motor neuron abnormalities, and grand mal seizures, but retained largely normal intelligence, until death at age 21. Severe loss of nigral and craniospinal motor neurons was noted postmortem. Round, eosinophilic, autofluorescent inclusion bodies, 3 to 10 microns in diameter, were observed in the nuclei of most nerve cell types of the central and peripheral nervous systems and retina. Ultrastructurally the inclusions appeared as masses of filaments without a limiting membrane, the constituent filaments having a diameter of 8.5 to 9.5 nm. Histochemical results suggested the presence of proteins with a high content of tryptophan. Four similar cases have been reported previously under various designations. We propose the name neuronal intranuclear inclusion disease for the disorder.