A decamer duplication in the 3' region of the BRI gene originates an amyloid peptide that is associated with dementia in a Danish kindred

Anesthetic considerations in patients with Alzheimer's disease

Alzheimer's disease is a form of dementia that is estimated to affect approximately 3 to 4 million Americans. Given the substantial number of people affected with this disease, it is likely that anesthesiologists will encounter many patients with Alzheimer's disease. Questions as to potential problems including informed consent, drug interactions, and preoperative progression of the disease may arise. This review describes anesthetic considerations, including pharmacologic and physiologic issues, in this growing population.

Complement activation in chromosome 13 dementias. Similarities with Alzheimer's disease

Chromosome 13 dementias, familial British dementia (FBD) and familial Danish dementia (FDD), are associated with neurodegeneration and cerebrovascular amyloidosis, with striking neuropathological similarities to Alzheimer's disease (AD). Despite the structural differences among the amyloid subunits (ABri in FBD, ADan in FDD, and Abeta in AD), these disorders are all characterized by the presence of neurofibrillary tangles and parenchymal and vascular amyloid deposits co-localizing with markers of glial activation, suggestive of local inflammation. Proteins of the complement system and their pro-inflammatory activation products are among the inflammation markers associated with AD lesions. Immunohistochemistry of FBD and FDD brain sections demonstrated the presence of complement activation components of the classical and alternative pathways as well as the neo-epitope of the membrane attack complex. Hemolytic experiments and enzyme-linked immunosorbent assays specific for the activation products iC3b, C4d, Bb, and C5b-9 indicated that ABri and ADan are able to fully activate the complement cascade at levels comparable to those generated by Abeta1-42. ABri and ADan specifically bound C1q with high affinity and formed stable complexes in physiological conditions. Activation proceeds approximately 70-75% through the classical pathway while only approximately 25-30% seems to occur through the alternative pathway. The data suggest that the chronic inflammatory response generated by the amyloid peptides in vivo might be a contributing factor for the pathogenesis of FBD and FDD and, in more general terms, to other neurodegenerative conditions.

Amyloidosis and Alzheimer's disease

Alzheimer's disease (AD) is the most frequent type of amyloidosis in humans and the commonest form of dementia. Extracellular Abeta amyloid deposits in the form of amyloid plaques and cerebral amyloid angiopathy as well as intraneuronal neurofibrillary tangles co-exist in the brain parenchyma of AD patients, the cognitive areas being the most severely affected. This review focuses on the potential role of amyloid in the development of neurodegeneration and presents studies of AD and other unrelated inherited dementia syndromes associated with neuronal loss and amyloid deposition in the brain.

Rat blood-brain barrier genomics. II

The tissue-specific gene expression at the brain microvasculature, which forms the blood-brain barrier (BBB) can be elucidated with a brain vascular genomics program, which starts with the isolation of gene products derived from purified brain microvessels. Genes commonly expressed in peripheral organs are subtracted with the suppression subtractive hybridization method using driver cDNA produced from a pool of rat liver/kidney-derived poly A+RNA. From a screen of 480 clones in the subtracted tester cDNA library, 156 clones were sequenced. The clones fell into 3 groups: known genes (51%), rat expressed sequence tags (31%), and novel rat genes not found in databases (18%). The known genes could be categorized into families of common function including vascular remodeling, signal transduction, transcription factors, biologic transport, vascular amyloid, hemostasis, myelin, lipids, secretion, cytoskeleton, and junctional complexes. Brain vascular genomics, or BBB genomics, allows for an accelerated discovery of the gene families that are differentially expressed at the microvasculature in brain.

Paradigm shifts in Alzheimer's disease and other neurodegenerative disorders: the emerging role of oligomeric assemblies

Alzheimer's disease (AD) is a progressive, neurodegenerative disorder characterized by amyloid deposition in the cerebral neuropil and vasculature. These amyloid deposits comprise predominantly fragments and full-length (40 or 42 residue) forms of the amyloid beta-protein (Abeta) organized into fibrillar assemblies. Compelling evidence indicates that factors that increase overall Abeta production or the ratio of longer to shorter forms, or which facilitate deposition or inhibit elimination of amyloid deposits, cause AD or are risk factors for the disease. In vitro studies have demonstrated that fibrillar Abeta has potent neurotoxic effects on cultured neurons. In vivo experiments in non-human primates have demonstrated that Abeta fibrils directly cause pathologic changes, including tau hyperphosphorylation. In concert with histologic studies revealing a lack of tissue injury in areas of the neuropil in which non-fibrillar deposits were found, these data suggested that fibril assembly was a prerequisite for Abeta-mediated neurotoxicity in vivo. Recently, however, both in vitro and in vivo studies have revealed that soluble, oligomeric forms of Abeta also have potent neurotoxic activities, and in fact, may be the proximate effectors of the neuronal injury and death occurring in AD. A paradigm shift is thus emerging that necessitates the reevaluation of the relative importance of polymeric (fibrillar) vs. oligomeric assemblies in the pathobiology of AD. In addition to AD, an increasing number of neurodegenerative disorders, including Parkinson's disease, familial British dementia, familial amyloid polyneuropathy, amyotrophic lateral sclerosis, and prion diseases, are associated with abnormal protein assembly processes. The archetypal features of the assembly-dependent neuropathogenetic effects of Abeta may thus be of relevance not only to AD but to these other disorders as well.

Inherited dementias

Dementia, defined as progressive cognitive decline, is a feature of a wide variety of genetic disorders. For example, a search of "dementia" in the Online Mendelian Inheritance in Man (www.ncbi.nlm.nih.gov/Omim) reveals 162 entries. Therefore this article cannot be encyclopedic and will be necessarily restricted to more prevalent or illustrative etiologies of familial dementia in adults. These disorders also have in common an initial and primarily dementing clinical presentation. Thus, this article is limited to: familial Alzheimer's disease (AD) and related amyloid angiopathies, frontotemporal dementias (FTD) and related tauopathies, familial prion diseases, British and Danish familial dementias, and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

BRICHOS: a conserved domain in proteins associated with dementia, respiratory distress and cancer

A novel domain (the BRICHOS domain) of approximately 100 amino acids has been identified in several previously unrelated proteins that are linked to major diseases. These include BRI(2), which is related to familial British and Danish dementia (FBD and FDD); Chondromodulin-I (ChM-I), related to chondrosarcoma; CA11, related to stomach cancer; and surfactant protein C (SP-C), related to respiratory distress syndrome (RDS). In several of these, the conserved BRICHOS domain is located in the propeptide region that is removed after proteolytic processing. Experimental data suggest that the role of this domain could be related to the complex post-translational processing of these proteins.

Transmissibility of systemic amyloidosis by a prion-like mechanism

The generation of amyloid fibrils from an amyloidogenic polypeptide occurs by a nucleation-dependent process initiated in vitro by seeding the protein solution with preformed fibrils. This phenomenon is evidenced in vivo by the fact that amyloid protein A (AA) amyloidosis in mice is markedly accelerated when the animals are given, in addition to an inflammatory stimulus, an i.v. injection of protein extracted from AA amyloid-laden mouse tissue. Heretofore, the chemical nature of this "amyloid enhancing factor" (AEF) has not been definitively identified. Here we report that the active principle of AEF extracted from the spleen of mice with silver nitrate-induced AA amyloidosis was identified unequivocally as the AA fibril itself. Further, we demonstrated that this material was extremely potent, being active in doses <1 ng, and that it retained its biologic activity over a considerable length of time. Notably, the AEF was also effective when administered orally. Our studies have provided evidence that AA and perhaps other forms of amyloidosis are transmissible diseases, akin to the prion-associated disorders.

Familial Danish dementia: a novel form of cerebral amyloidosis associated with deposition of both amyloid-Dan and amyloid-beta

Familial Danish dementia (FDD) is pathologically characterized by widespread cerebral amyloid angiopathy (CAA), parenchymal protein deposits, and neurofibrillary degeneration. FDD is associated with a mutation of the BRI2 gene located on chromosome 13. In FDD there is a decamer duplication, which abolishes the normal stop codon, resulting in an extended precursor protein and the release of an amyloidogenic fragment, ADan. The aim of this study was to describe the major neuropathological changes in FDD and to assess the distribution of ADan lesions, neurofibrillary pathology, glial, and microglial response using conventional techniques, immunohistochemistry, confocal microscopy, and immunoelectron microscopy. We showed that ADan is widely distributed in the central nervous system (CNS) in the leptomeninges, blood vessels, and parenchyma. A predominance of parenchymal pre-amyloid (non-fibrillary) lesions was found. Abeta was also present in a proportion of both vascular and parenchymal lesions. There was severe neurofibrillary pathology, and tau immunoblotting revealed a triplet electrophoretic migration pattern comparable with PHF-tau. FDD is a novel form of CNS amyloidosis with extensive neurofibrillary degeneration occurring with parenchymal, predominantly pre-amyloid rather than amyloid, deposition. These findings support the notion that parenchymal amyloid fibril formation is not a prerequisite for the development of neurofibrillary tangles. The significance of concurrent ADan and Abeta deposition in FDD is under further investigation.

Proteolytic processing of familial British dementia-associated BRI variants: evidence for enhanced intracellular accumulation of amyloidogenic peptides

Different mutations in the BRI(2) gene cause rare neurodegenerative conditions, termed familial British dementia (FBD) and familial Danish dementia (FDD). The mutant genes encode BRI-L and BRI-D, the precursors of fibrillogenic ABri and ADan peptides, respectively. We previously reported that furin processes both BRI-L and its wild type counterpart, BRI, resulting in the secretion of C-terminal peptides; elevated levels of peptides were generated from BRI-L. In the present study, we show that inducible expression of alpha1-antitrypsin Portland, a furin inhibitor, inhibits the endoproteolysis of BRI and BRI-L in a dose-dependent manner. Moreover, comparison of the activities of several proprotein convertases reveals that furin is most efficient in endoproteolysis of BRI and BRI-L; PACE4, PC6A, PC6B, and LPC show much lower activities. Interestingly, LPC also exhibits enhanced cleavage of BRI-L compared with BRI. Finally, we demonstrate that BRI-D is also processed by furin and, like BRI-L, the cleavage of BRI-D is more efficient than that of BRI. Interestingly, while the ABri peptide is detected both intracellularly and in the medium, the ADan peptide accumulates predominantly in intracellular compartments. We propose that intracellular accumulation of amyloidogenic ADan or ABri peptides results in the neuronal damage leading to FDD and FBD, respectively.

Chromosome 13 dementia syndromes as models of neurodegeneration

Two hereditary conditions, familial British dementia (FBD) and familial Danish dementia (FDD), are associated with amyloid deposition in the central nervous system and neurodegeneration. The two amyloid proteins, ABri and ADan, are degradation products of the same precursor molecule BriPP bearing different genetic defects, namely a Stop-to-Arg mutation in FBD and a ten-nucleotide duplication-insertion immediately before the stop codon in FDD. Both de novo created amyloid peptides have the same length (34 amino acids) and the same post-translational modification (pyroglutamate) at their N-terminus. Neurofibrillary tangles containing the classical paired helical filaments as well as neuritic components in many instances co-localize with the amyloid deposits. In both disorders, the pattern of hyperphosphorylated tau immunoreactivity is almost indistinguishable from that seen in Alzheimer's disease. These issues argue for the primary importance of the amyloid deposits in the mechanism(s) of neuronal cell loss. We propose FBD and FDD, the chromosome 13 dementia syndromes, as models to study the molecular basis of neurofibrillary degeneration, cell death and amyloid formation in the brain.

Systemic amyloid deposits in familial British dementia

Familial British dementia (FBD) is an early onset inherited disorder that, like familial Alzheimer's disease (FAD), is characterized by progressive dementia, amyloid deposition in the brain, and neurofibrillary degeneration of limbic neurons. The primary structure of the amyloid subunit (ABri) extracted from FBD brain tissues (Vidal, R., Frangione, B., Rostagno, A., Mead, S., Revesz, T., Plant, G., and Ghiso, J. (1999) Nature 399, 776-781) is entirely different and unrelated to any previously known amyloid protein. Patients with FBD have a single nucleotide substitution at codon 267 in the BRI2 gene, resulting in an arginine replacing the stop codon and a longer open reading frame of 277 amino acids instead of 266. The ABri peptide comprises the 34 C-terminal residues of the mutated precursor ABriPP-277 and is generated via furin-like proteolytic processing. Here we report that carriers of the Stop-to-Arg mutation have a soluble form of the amyloid peptide (sABri) in the circulation with an estimated concentration in the range of 20 ng/ml, several fold higher than that of soluble Abeta. In addition, ABri species identical to those identified in the brain were also found as fibrillar components of amyloid deposits predominantly in the blood vessels of several peripheral tissues, including pancreas and myocardium. We hypothesize that the high concentration of the soluble de novo created amyloidogenic peptide and/or the insufficient tissue clearance are the main causative factors for the formation of amyloid deposits outside the brain. Thus, FBD constitutes the first documented cerebral amyloidosis associated with neurodegeneration and dementia in which the amyloid deposition is also systemic.

Renal amyloidosis caused by a novel stop-codon mutation in the apolipoprotein A-II gene

BACKGROUND

Although apolipoprotein A-II (apoA-II) associated amyloidosis has been described in the senescent accelerated mouse (SAM) model of aging, so far there has been no report of human apoA-II amyloidosis except for a recent report of renal amyloidosis resulting from a stop-codon to glycine mutation of apoA-II. The mechanisms of amyloid formation in human apoA-II amyloidosis are not clear.

METHODS

A 46-year-old Caucasian male with proteinuria noted at 42 years of age was studied. Renal biopsy revealed amyloid deposition in glomeruli. DNA analysis of genes known to be associated with hereditary renal amyloidosis revealed no abnormalities. To elucidate the type of his amyloidosis, apoA-II gene and plasma apoA-II were examined.

RESULTS

DNA analysis revealed heterozygosity for a G to C transversion at the second position of the stop-codon of apoA-II gene, suggesting a stop to serine substitution at codon 78. Western blot analysis and amino acid sequence analysis of the patient's plasma apoA-II showed both normal apoA-II and variant apoA-II with a 21-amino acid residue extension at the C-terminus.

CONCLUSIONS

These results indicate that the patient's amyloid fibrils were derived from apoA-II and the amyloidogenesis is likely to be closely linked to the peptide extension at the C-terminus of variant apoA-II. The pathogenesis of human apoA-II amyloidosis is different from that of SAM.

Gene identification in Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia in the elderly population. Three genes have been identified that cause the less common early-onset, familial cases of the disease: the amyloid precursor (APP) protein gene on chromosome 21, the presenilin 1 (PSEN1) gene on chromosome 14 and the presenilin 2 (PSEN2) gene on chromosome 1. Mutations in these genes account for << 2% of the total number of AD cases. More than 50% of the cases are late-onset and related to the apolipoprotein E (APOE) gene on chromosome 19. The apolipoprotein E locus is a susceptibility gene, with polymorphisms affecting both risk and age-of-onset of the disease. Intense efforts are underway to identify additional susceptibility genes and promising regions on chromosomes 6, 9, 10 and 12 have been identified through whole genome scans. In addition, the genetic basis of several other non-AD inherited dementias has been unravelled. Discovery of the genetically relevant genes will aid in the elucidation of the pathogenesis of AD. The high-throughput tools of pharmacogenomics for gene-to-function-to-target studies can provide a quicker means of monitoring how mutations and polymorphisms affect model systems' adaptations to the altered genes, possibly identifying signal transduction or biochemical pathways. This relevant information can then be used for drug target selection and pharmacogenetics.

Advances in molecular genetics and pathology of cerebrovascular disorders

Progress in molecular genetics has enabled the dissection of several autosomal dominantly inherited forms of cerebrovascular disorders. Mutations in diverse genes might induce pathological changes in intracranial vessels, resulting in cerebral haemorrhages and ischaemic strokes. Such pathologies, however, might also result from systemic vascular disease caused by mutations or polymorphisms in genes that regulate cardiovascular physiology, blood coagulation, lipid metabolism and metabolic functions. Interestingly, several mutations that directly affect CNS vasculature involve genes that control inter- or intracellular signalling functions. Although highly variable phenotypes make it difficult to pinpoint the genotypes, genetic characterization of cerebrovascular disorders is valuable for understanding the pathogenesis and management of sporadic disease.

Non-fibrillar oligomeric species of the amyloid ABri peptide, implicated in familial British dementia, are more potent at inducing apoptotic cell death than protofibrils or mature fibrils

Familial British dementia (FBD) is an autosomal dominant neurodegenerative disorder, with biochemical and pathological similarities to Alzheimer's disease. FBD is associated with a point mutation in the stop codon of the BRI gene. The mutation extends the length of the wild-type protein by 11 amino acids, and following proteolytic cleavage, results in the production of a cyclic peptide (ABri) 11 amino acids longer than the wild-type (WT) peptide produced from the normal gene BRI. ABri was found to be the main component of amyloid deposits in FBD brains. However, pathological examination of FBD brains has shown the presence of ABri as non-fibrillar deposits as well as amyloid fibrils. Taken together, the genetic, pathological and biochemical data support the hypothesis that ABri deposits play a central role in the pathogenesis of FBD. Here we report that ABri, but not WT peptide, can oligomerise and form amyloid-like fibrils. We show for the first time that ABri induces apoptotic cell death, whereas WT is not toxic to cells. Moreover, we report the novel findings that non-fibrillar oligomeric species of ABri are more toxic than protofibrils and mature fibrils. These findings provide evidence that non-fibrillar oligomeric species are likely to play a critical role in the pathogenesis of FBD and suggest that a similar process may also operate in other neurodegenerative diseases.

Spontaneous hemorrhagic stroke in a mouse model of cerebral amyloid angiopathy

A high risk factor for spontaneous and often fatal lobar hemorrhage is cerebral amyloid angiopathy (CAA). We now report that CAA in an amyloid precursor protein transgenic mouse model (APP23 mice) leads to a loss of vascular smooth muscle cells, aneurysmal vasodilatation, and in rare cases, vessel obliteration and severe vasculitis. This weakening of the vessel wall is followed by rupture and bleedings that range from multiple, recurrent microhemorrhages to large hematomas. Our results demonstrate that, in APP transgenic mice, the extracellular deposition of neuron-derived beta-amyloid in the vessel wall is the cause of vessel wall disruption, which eventually leads to parenchymal hemorrhage. This first mouse model of CAA-associated hemorrhagic stroke will now allow development of diagnostic and therapeutic strategies.

Sequence, genomic structure and tissue expression of Human BRI3, a member of the BRI gene family

The BRI3 gene is a member of the BRI gene family, made up of at least three different genes (BRI1-3). Previous studies established the cDNA sequence and structure of the human and mouse BRI1 and BRI2 genes and we recently reported that mutations in the BRI2 isoform, located on chromosome 13, are associated with dementia in humans. In the present work, we determine the complete cDNA sequence and genomic organization of the human BRI3 gene. BRI3 codes for a polypeptide of 267 amino acids, with a Mr of 30 KDa and a pI of 8.47. The amino acid sequence is 43.7% identical to the sequence of the human BRI2, and 38.3% identical to that of human BRI1, with the highest percentage of amino acid identity being concentrated on the C-terminal half of the molecules. In Northern blots, BRI3 cDNA hybridizes only one message of approximately 2.1 kilobases, which is predominantly present in the human brain. The BRI3 gene is localized on chromosome 2 and consists of six exons spanning more than 20 kb. Homology search of EST data banks retrieved a Caenorhabditis briggsae homolog of BRI, indicating that the BRI gene belongs to a strongly conserved gene family. These studies, aimed at characterizing the members of the BRI gene family, may provide valuable clues to the understanding of their normal function and how mutations in BRI2 can cause neurodegeneration and dementia similar to Alzheimer's disease.

A new human hereditary amyloidosis: the result of a stop-codon mutation in the apolipoprotein AII gene

Hereditary systemic amyloidosis may be caused by mutations in a number of plasma proteins including transthyretin, apolipoprotein AI, fibrinogen Aalpha-chain, lysozyme, and gelsolin. Each type of amyloidosis is inherited as an autosomal dominant disease and is associated with a structurally altered protein that aggregates to form amyloid fibrils. Here we report that the amyloid protein in a family with previously uncharacterized hereditary renal amyloidosis is apolipoprotein AII (apoAII) with a 21-residue peptide extension on the carboxyl terminus. Sequence analysis of the apoAII gene of affected individuals showed heterozygosity for a single base substitution in the apoAII stop codon. The mutation results in extension of translation to the next in-frame stop codon 60 nucleotides downstream and is predicted to give a 21-residue C-terminal extension of the apoAII protein identical to that found in the amyloid. This mutation produces a novel BstNI restriction site that can be used to identify individuals with this gene by restriction fragment length polymorphism analysis. This is the first report of apoAII amyloid in humans and the first mutation identified in apoAII protein. Amyloid fibril formation from apoAII suggests that this lipoprotein, which is predicted to have an amphipathic helical structure, must undergo a transition to a beta-pleated sheet by a mechanism shared by other lipoproteins that form amyloid.

A pathogenic presenilin-1 deletion causes abberrant Abeta 42 production in the absence of congophilic amyloid plaques

Familial Alzheimer's disease (FAD) is frequently associated with mutations in the presenilin-1 (PS1) gene. Almost all PS1-associated FAD mutations reported so far are exchanges of single conserved amino acids and cause the increased production of the highly amyloidogenic 42-residue amyloid beta-peptide Abeta42. Here we report the identification and pathological function of an unusual FAD-associated PS1 deletion (PS1 DeltaI83/DeltaM84). This FAD mutation is associated with spastic paraparesis clinically and causes accumulation of noncongophilic Abeta-positive "cotton wool" plaques in brain parenchyma. Cerebral amyloid angiopathy due to Abeta deposition was widespread as were neurofibrillary tangles and neuropil threads, although tau-positive neurites were sparse. Although significant deposition of Abeta42 was observed, no neuritic pathology was associated with these unusual lesions. Overexpressing PS1 DeltaI83/DeltaM84 in cultured cells results in a significantly elevated level of the highly amyloidogenic 42-amino acid amyloid beta-peptide Abeta42. Moreover, functional analysis in Caenorhabditis elegans reveals reduced activity of PS1 DeltaI83/DeltaM84 in Notch signaling. Our data therefore demonstrate that a small deletion of PS proteins can pathologically affect PS function in endoproteolysis of beta-amyloid precursor protein and in Notch signaling. Therefore, the PS1 DeltaI83/DeltaM84 deletion shows a very similar biochemical/functional phenotype like all other FAD-associated PS1 or PS2 point mutations. Since increased Abeta42 production is not associated with classical senile plaque formation, these data demonstrate that amyloid plaque formation is not a prerequisite for dementia and neurodegeneration.

Spontaneous hemorrhagic stroke in a mouse model of cerebral amyloid angiopathy

A high risk factor for spontaneous and often fatal lobar hemorrhage is cerebral amyloid angiopathy (CAA). We now report that CAA in an amyloid precursor protein transgenic mouse model (APP23 mice) leads to a loss of vascular smooth muscle cells, aneurysmal vasodilatation, and in rare cases, vessel obliteration and severe vasculitis. This weakening of the vessel wall is followed by rupture and bleedings that range from multiple, recurrent microhemorrhages to large hematomas. Our results demonstrate that, in APP transgenic mice, the extracellular deposition of neuron-derived beta-amyloid in the vessel wall is the cause of vessel wall disruption, which eventually leads to parenchymal hemorrhage. This first mouse model of CAA-associated hemorrhagic stroke will now allow development of diagnostic and therapeutic strategies.

Regional distribution of amyloid-Bri deposition and its association with neurofibrillary degeneration in familial British dementia

Familial British dementia (FBD), pathologically characterized by cerebral amyloid angiopathy (CAA), amyloid plaques, and neurofibrillary degeneration, is associated with a stop codon mutation in the BRI gene resulting in the production of an amyloidogenic fragment, amyloid-Bri (ABri). The aim of this study was to assess the distribution of ABri fibrillar and nonfibrillar lesions and their relationship to neurofibrillary pathology, astroglial and microglial response using immunohistochemistry, confocal microscopy, and immunoelectron microscopy in five cases of FBD. Abnormal tau was studied with immunoblotting. We present evidence that ABri is deposited throughout the central nervous system in blood vessels and parenchyma where both amyloid (fibrillar) and pre-amyloid (nonfibrillar) lesions are formed. Ultrastructurally amyloid lesions appear as bundles of fibrils recognized by an antibody raised against ABri, whereas Thioflavin S-negative diffuse deposits consist of amorphous electron-dense material with sparse, dispersed fibrils. In contrast to nonfibrillar lesions, fibrillar ABri is associated with a marked astrocytic and microglial response. Neurofibrillary tangles and neuropil threads occurring mainly in limbic structures, are found in areas affected by all types of ABri lesions whereas abnormal neurites are present around amyloid lesions. Immunoblotting for tau revealed a triplet electrophoretic migration pattern. Our observations confirm a close link between ABri deposition and neurodegeneration in FBD.

Ocular changes in heredo-oto-ophthalmo-encephalopathy

BACKGROUND

Heredo-oto-ophthalmo-encephalopathy (HOOE) is a dominantly inherited disease characterised by gradual loss of vision from the age of 20, progressive hearing loss from the late 20s, cerebellar ataxia in the 30s, and death in dementia in the fourth or fifth decade. Currently, no detailed description has been given of the ocular changes seen in HOOE. Therefore, the ocular changes of HOOE were described on the basis of clinical and histological data from six affected family members.

METHODS

Three members of the family affected by HOOE were subjected to a full ophthalmological re-examination, and postmortem examination was done on three eyes from two affected family members.

RESULTS

Visual loss in HOOE was caused by posterior subcapsular cataract and retinal neovascularizations leading to vitreous haemorrhages and neovascular glaucoma. In the retina there was extensive accumulation of an amyloid material, both diffusely and in the walls of the retinal vessels. The retinal glial cells showed extensive pathological changes and retinal Müller cells were seen to occlude the lumen of retinal vessels.

CONCLUSION

Heredo-oto-ophthalmo-encephalopathy is a familial amyloidosis of the central nervous system which is different from previously reported cases of amyloidosis by including cataract and retinal neovascularizations. The disease is accompanied by extensive changes in retinal glial cells that may play a part in the pathophysiology of the ocular complications of the disease.

Familial British dementia with amyloid angiopathy: early clinical, neuropsychological and imaging findings

Familial British dementia with amyloid angiopathy (FBD) is an autosomal dominant condition characterized by a dementia, progressive spastic tetraparesis and cerebellar ataxia with onset in the sixth decade. A point mutation in the BRI gene has been shown to be the genetic abnormality. Genealogical work with the large family originally reported by Worster-Drought and updated by Plant has identified nine generations dating back to the late eighteenth century. The pedigree now includes six living affected patients, 35 historical cases, and 52 descendants at risk of having inherited the disease. A common ancestor has been identified between the large pedigree and a case report of 'familial cerebellar ataxia with amyloid angiopathy'. An autopsy case from a separate family with an identical condition is described but no common ancestor with the large pedigree has been found. Case histories have been researched and updated in each pedigree. Eleven individuals at risk of FBD, aged between 44 and 56 years, agreed to undergo a clinical and neuropsychological assessment along with MRI brain imaging in order to clarify early diagnostic features. Five of the eleven were thought to show early clinical signs of the disease. Neurological examination was abnormal in three, with limb and gait ataxia and mild spastic paraparesis. Three had impaired recognition and recall memory and another had mild impairment of delayed visual recall. All affected individuals had an abnormal MRI of the brain, consisting of deep white-matter hyperintensity (T(2)-weighted scans) and lacunar infarcts, but no intracerebral haemorrhage. The corpus callosum was affected particularly, and in one patient it was severely atrophic.

The cerebral proteopathies: neurodegenerative disorders of protein conformation and assembly

The abnormal assembly and deposition of specific proteins in the brain is the probable cause of most neurodegenerative disease afflicting the elderly. These "cerebral proteopathies" include Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), prion diseases, and a variety of other disorders. Evidence is accumulating that the anomalous aggregation of the proteins, and not a loss of protein function, is central to the pathogenesis of these diseases. Thus, therapeutic strategies that reduce the production, accumulation, or polymerization of pathogenic proteins might be applicable to a wide range of some of the most devastating diseases of old age.