[Prions, epidemic of Creutzfeldt-Jakob variant disease and global emergency]

We present here the current understanding of "prion" theory and global risk for epidemics of variant Creutzfeldt-Jakob disease (vCJD). Prion is the infectious agent of all transmissible spongiform encephalopaties (TSEs). It is regarded as an aggregate of a pathological conformer (PrPSc) of a normal cellular glycoprotein (PrPC) encoded by a gene, in humans on chromosome 20. The differences between PrPSc and PrPC are largely if not exclusively conformational; PrPC is mostly alpha-helical while PrPSc, beta-pleeted. Furthermore, mutations within the coding sequence (open reading frame) of PrP gene are linked with phenotypic expression of CJD, Gerstmann-Straussler-Scheinker disease (GSS) and fatal familial insomnia (FFI). VCJD is caused by transmission from cattle infected with bovine spongiform encephalopathy (BSE). PrP purified from vCJD-affected brains is characterised by the so called fourth type of glycosylation pattern. The neuropathological hallmark of vCJD is the florid plaque, an amyloid plaque surrounded by a corona of spongiform change. VCJD affects mostly young people (range: 13-74 years) and it is clinically distinguishable from sporadic CJD. The extent of epidemics is currently unknown; but its dynamic (102 cases until July 2001) may suggest "the worst" scenario.

[Clinical application of proton magnetic resonance spectroscopy for differential diagnosis of pediatric posterior fossa tumors]

We report here on a correlation between proton magnetic resonance spectroscopy (MRS) spectra obtained in children with posterior fossa tumors and tumor histology and grading. Twenty-six children (age 1-16) were investigated before surgery by using single-voxel proton MRS. All examination were performed on a 1.5 T MR scanner by using single-voxel (8 cm3) with PRESS sequence (TR 1600 ms, TE 270 ms, NEX 256). Spectra of N-acetylaspartate (NAA), choline containing compounds (Cho), creatine and phosphocreatine (Cr) and lactate (Lac) were evaluated. Absolute concentrations of the metabolites were measured and their ratios were calculated. Correlation between these and tumor histology and grading were then determined. Concentration of Cho and Lac, and Cho/NAA ratio were the major statistically significant parameters for discrimination between benign (WHO grade I and II) and malignant tumors (WHO grade III and IV), in particular between pilocytic astrocytomas and medulloblastomas. Discrimination between individual histological types within malignant and benign tumor groups was not possible. Proton MRS of pediatric posterior fossa tumors seems to be helpful in prediction of tumor grading and histology. Specific character of the examination requires establishing of the individual standards for every MR scanner.

Tropical spastic paraparesis

Human T-cell lymphotropic virus type I (HTLV-I) is the cause of endemic tropical spastic paraparesis (TSP) or HTLV-I-associated myelopathy (HAM). Because TSP/HAM is not a fatal disease, the neuropathology of this disease, albeit relatively well understood, is based on the examination of just a few incidental cases. We summarise our experience with the neuropathology of tropical spastic paraparesis/HTLV-I associated myelopathy (TSP/HAM). We studied three cases of TSP/HAM from different parts of the world. We demonstrated peculiar lamellated structures, called "multilamellar bodies" (MLB). It is tempting to suggest that MLB may represent specific ultrastructural markers of TSP/HAM. The pathology of the anteriorand posterior horns was similar and comprised axonal degeneration, accompanied by extensive astrocytic gliosis. Lymphocytic infiltration, particularly observed as "cuffs" around blood vessels, was scattered among other cellular elements. Ultrastructurally, myelin sheaths were relatively well preserved, and some demyelinated but not remyelinated fibres were observed. Moreover, axons with abnormal accumulations of neurofilaments, suggestive of axonal degeneration, were detected. Several axons contained Hirano bodies. In many samples glial processes replaced most of the remaining neuropil.

A special report I. Prion protein (PrP)--amyloid plaques in the transmissible spongiform encephalopathies, or prion diseases revisited

We present a retrospective analysis of PrP-amyloid plaques encountered in CJD and GSS. In human TSEs (kuru, CJD and GSS) several PrP-immunopositive plaques and plaque-like deposits were detected. In kuru, plaques were typical "kuru" plaques--stellate structures deposited mostly in the granular- and Purkinje-cell layer of the cerebellum. Many smaller or larger clusters were visible but, in contrast to GSS, they never merged together to form multicentric plaques. In all cases of GSS, plaques were localised in the granular- and Purkinje-cell layer and the molecular cell layer. There were many different forms of plaques: from kuru plaques (unicentric stellate plaques) to clusters of unicentric plaques, which by merging eventually formed "multicentric plaques". The latter are the hallmark of this disease. By electron microscopy, several types of amyloid plaques, which corresponded to those seen by PrP immunohistochemistry, were observed. The first type, unicentric "kuru" plaque, consisted of stellate arrangements (stars or cores) of amyloid bundles emanating from a densely interwoven centre. Amyloid stars were surrounded by astrocytic processes and invaded by microglial cells but dystrophic neurites were only rarely seen. In contrast, multicentric plaques were often surrounded by dystrophic neurites. The rarest type of plaque were neuritic plaques. In 263K- and 22C-H scrapie-infected hamster brains, by light microscopy and semi-thin (1 microm) sections, discrete PrP-immunopositive plaques were observed in the subependymal region but not in the deep brain neuroparenchyma. These plaques were not discernible by routine H & E staining. Ultrastructurally, plaques were recognised as areas of low electron density containing haphazardly-oriented fibrils and not as stellate compact structures typical of plaques in human cases of CJD and GSS. These plaques were located beneath the basal border of the ependymal cells and adjacent blood vessels. Occasional dystrophic neurites containing electron-dense inclusion bodies were seen within the plaque perimeter, which always remained PrP-negative.

A special report I. Prion protein (Prp)--amyloid plaques in the transmissible spongiform encephalopathies (TSEs) or prion disease revisited

We present a retrospective analysis of PrP-amyloid plaques encountered in CJD and GSS. In human TSEs (kuru, CJD and GSS) several PrP-immunopositive plaques and plaque-like deposits were detected. In kuru, plaques were typical "kuru" plaques--stellate structures deposited mostly in the granular and Purkinje cell layer of the cerebellum. Many smaller or larger clusters were visible but, in contrast to GSS, they never have merged together to form multicentric plaques. In all cases of GSS, plaques were located in the granular and Purkinje cell layer and in the molecular layer. There were many different forms of plaques: from kuru plaques (unicentric stellate plaques) to clusters of unicentric plaques which by merging eventually formed "multicentric plaques". The latter are the hallmark of this disease. By electron microscopy several types of amyloid plaques, which corresponded to those seen by PrP immunohistochemistry were observed. The first type, unicentric kuru plaque consisted of stellate arrangements (stars or cores) of amyloid bundles emanating from a densely interwoven center. Amyloid stars were surrounded by astrocytic processes and invaded by microglial cells but dystrophic neurites were only rarely seen. In contrast multicentric plaques were often surrounded by dystrophic neurites. The rarest type of plaque, were neuritic plaques. In 263K and 22C-H scrapie-infected hamster brains, on the light microscopy of the semi-thin (1 micron) sections, discrete PrP-immunopositive plaques were observed in the subependymal region but not in the deep brain neuroparenchyma. These plaques were not discernible by routine HE staining. Ultrastructurally, plaques were recognized as areas of low electron density containing haphazardly-oriented fibrils and not as stellate compact structures typical of plaques in human cases of CJD and GSS. These plaques were located beneath the basal border of the ependymal cells and adjacent blood vessels. Occasional dystrophic neurites containing electron-dense inclusion bodies were seen within the plaque perimeter, which always remained PrP-negative.

A new point mutation of the PRNP gene in Gerstmann-Sträussler-Scheinker case in Poland

We report here a case of Gerstmann-Sträussler-Scheinker (GSS) disease with a new mutation at the codon 232 (Met to Thr) of the PRNP gene. This case was characterized by PrP-immunopositive kuru and multicentric plaques; these plaques were also seen in the cerebral cortex, hippocampus and in the deep subcortical nuclei. Diffuse PrP depositions were also detected. In the temporal cortex, a few plaques were immunopositive for both PrP and Abeta; the latter was expressed at the periphery of the PrP-immunopositive cores. This mutation was absent from 40 healthy Polish controls and from 16 other Polish CJD cases, and we therefore believe that 232Thr is a new pathogenic mutation and not a benign polymorphism.

Ultrastructural pathology of Creutzfeldt-Jakob disease and fatal familial insomnia

In this study we examined well fixed brain biopsies of 9 sporadic CJD, 9 iatrogenic CJD cases, 2 hereditary CJD (Gly200Lys and Val203Iso), a case of vCJD and a case of fatal familial insomnia (FFI) from a new French family collected over the years at the Service de Neuropathologie, Hopital Neurologique, Lyon, France. Tubulovesicular structures (TVS) were found in every case including FFI and nvCJD. Thus, TVS, as we suggested previously are important pathologic structure which significance should be more extensively studied.

The morphometric analysis and recognition an amyloid plaque in microscope images by computer image processing

This paper presents an approach of the two-dimensional image processing application in recognition of amyloid plaque in microscope images of the brain tissues. The authors propose to create universal amyloid plaque computer pattern and special multivariate image segmentation techniques based on collected images and statistical information. This recognition image procedure is divided into 3-dimensional statistical colour and morphological shape identifications. The developed computer system will collect and store image data and exchange them by network with other collaborated systems.

Bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease: a risk analysis

There is doubt that variant Creutzfeldt-Jakob disease (vCJD) resulted from bovine spongiform encephalopathy (BSE) transmission from cattle to human. What is uncertain is the total number of vCJD cases (currently about 80). In this review I covered recent data on the vCJD and BSE epidemic, the mode of BSE spreading to humans and, finally, the data on the PRNP analogue--the doppel gene (PRND).

Ultrastructural analysis of the florid plaque in variant Creutzfeldt-Jakob disease

We report here the first description of florid plaques--the hallmark of variant Creutzfeldt-Jakob disease (vCJD). These plaques are composed of broad bundles of amyloid, are highly neuritic and exhibited astrocytes and microglial cells. Collectively, they are more similar to neuritic plaques of Alzheimer's disease than to kuru plaques of kuru--Creutzfeldt-Jakob disease--Gerstmann-Sträussler-Sheinker disease.

Clinico-pathological analysis of pilocytic astrocytomas and gangliogliomas

A pathological analysis of 58 pilocytic astrocytomas (PA) and 11 gangliogliomas (GG) was performed using immunohistochemistry. Antibodies against neuronal and glial markers (GFAP, SYN, NFP) were used. An analysis of survivors using the Kaplan Meier curve was also performed and compared with the literature reports. During the retrospective review of 58 cases recognized primarily as PA, 11 verified neoplasms demonstrated strong, immunopositive reaction for SYN or NFP or both antibodies. These cases were reclassified as gangliogliomas (GG). None of the 11 tumors recognized as GG was reclassified as PA. The overall 5-year survival was 88.89% in the PA and 70% in GG groups.

How do neurons degenerate in prion diseases or transmissible spongiform encephalopathies (TSEs): neuronal autophagy revisited

As in other neurodegenerative diseases such as Alzheimer's disease, neurons in prion diseases or transmissible spongiform encephalopathies (TSEs) die via programmed cell death of which the apoptotic process is relatively well characterized. A subcellular alteration linked to apoptosis is the formation of autophagic vacuoles, which we and others demonstrated in CJD- and scrapie-affected rodent brains. Autophagy may co-exist with apoptosis or may precede it and the process may be induced by apoptotic stimuli. Here, we extend these observations using different model of scrapie and CJD. Both scrapie models (the 263K and 22C-H) demonstrated autophagic vacuoles with the same frequency; hence, they will be described together. While the following changes had been observed simultaneously in different areas of the same sample, this description is organised as if it followed a sequence of events. First, a part of the neuronal cytoplasm was sequestrated by concentric arrays of membrane; that part of the cytoplasm closed by membranes appeared relatively normal but its density often appeared increased. Next, electron density of the central dramatically increased. Then, membranes proliferated within the cytoplasm in a labyrinth-like manner and an area sequestrated by these membranes enlarged and became more complex structure consisting of vacuoles, electron-dense area and areas of normally-looking cytoplasm connected with convoluted membranes. Finally, a large area of the cytoplasm was transformed into a collection of autophagic vacuoles of different sizes. Virtually identical alterations, albeit with much lower frequency, were seen in terminally ill CJD-affected hamsters.

Ultrastructural studies of experimental scrapie and Creutzfeldt-Jakob disease in hamsters. I. Alterations of myelinated axons

Classical and ultrastructural neuropathology of prion diseases are generally well described. Here we report that alterations of myelinated fibres in hamsters infected either with polioencephalopathic strains of scrapie or panencephalopathic strains of CJD (Echigo-1) are virtually identical and differ only quantitatively. In contrast, mice infected with the panencephalopathic Fujisaki strain of CJD exhibited much more elaborate changes of myelinated fibres.

Codon 219 in Creutzfeldt-Jakob disease in Poland

Prion diseases are a group of etiologically heterogenous diseases. In addition to familial cases linked to mutations of PRNP open reading frame they include also cases of unknown etiology. One of the susceptibility factors to sporadic as well as iatrogenic prion diseases are PRNP polymorphisms. In the present study, we analyzed sequences of the PRNP gene codon 219 of 16 Polish CJD cases and we found heterozygous GAG to GAT changes on the sense strand and only wild type sequence on an antisense strand. The RFLP technique was used to verify this divergence and only wild type sequences were revealed.

Prion diseases: a dual view of the prion hypothesis as seen from a distance

We review the historical background and principles of the prion theory in its current shape. We showed that most of data may be still interpreted dually according to the protein only hypothesis and according to the theory in which additional component is necessary to comprise the infectivity. The enormous impact of structural biological studies is also stressed.

Ultrastructural studies of experimental scrapie and Creutzfeldt-Jakob disease in hamsters. II. Astrocytic and macrophage reaction towards axonal destruction

We report here the microglial (macrophage) and astrocytic reaction in several models of transmissible spongiform encephalopathies (TSEs) or prion diseases. With the low power electron microscopy it was readily apparent that myelinated vacuoles were surrounded by cells and their processes. The latter belonged either to hyperplastic reactive astrocytes or to macrophages. Typically, reactive astrocytes exhibited cytoplasm filled with innumerable glial filaments and, occasionally, other organelles (like cilia) and abundant tortuous intercellular junctions of adhesive plaque junction type. Desmosome-like junctions connecting astrocytic elements were also seen. As described earlier, astrocytic processes were occasionally interdigitated with oligodendroglial cells and their processes. Two types of macrophages were readily described. The majority of them exhibited electron-dense cytoplasm and numerous "empty" vacuoles (digestive chambers) containing cellular debris. Occasional vacuoles were surrounded by a thin collar reminiscent of "lyre-like inclusions" of the second type of macrophages. Several mylinated fibres were clearly engulfed by the cytoplasm of a macrophage containing unusual annulate lamellae.

Deposition patterns of disease-associated prion protein in captive mule deer brains with chronic wasting disease

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) in captive and free-ranging cervids in the USA; its origin is obscure. Archival formalin-fixed and paraffin-embedded specimens of 16 captive mule deer brains with CWD were analyzed using immunocytochemistry for the disease-associated prion protein (PrP). The most prominent pattern of PrP deposition were plaque-like structures, a substantial proportion of which were florid plaques surrounded by a rim of spongiform vacuoles. The percentage of florid plaques was highly variable according to region, ranging from 0% to 52.7%. The highest percentage was observed in the medulla and basal ganglia, the lowest in the cerebral cortex. Only three brains contained no florid plaques. There were also punctate synaptic-type and perivascular deposits, particularly in areas of severe spongiform change, and subpial and subependymal plaque-like deposits, whereas cerebellar involvement was mild. Thus, CWD brain pathology prominently features florid PrP plaques, as does variant Creutzfeldt-Jakob disease (vCJD), but differs in other characteristics from vCJD.

Dysembryoplastic neuroectodermal tumor: an ultrastructural study of six cases

Dysembryoplastic neuroectodermal tumor (DNT) is a rare brain neoplasm. Although the tumor pathology is relatively well charactererized, its full clinicopathological spectrum is still discussed, and ultrastructural data on it are very limited. Here, the authors describe detailed ultrastructural pathology of 7 cases of DNT. Each tumor consisted of 3 major elements: neoplastic cells (oligodendroglial-like cells, OLC), elongated processes forming neuropil-like structure, and expanded "mucoid" extracellular space, the latter giving an impression of cellular elements floating within it. Neoplastic cells had round, oval, or elongated nuclei, no discernible nucleoli, and a relatively narrow rim of cytoplasm. Some nuclei were irregular and invaginated, and pseudoinclusions (invaginations of cytoplasm penetrated into toroid-like nuclear formations) were observed. Part of the cytoplasm sequestrated within pseudoinclusions often appeared degenerated with large blebs and electron-lucent vesicles, and some of these contained, in turn, semicircular profiles of unknown significance. Chromatin was clustered below the nuclear membrane. The cytoplasm contained a few mitochondria, round rather than elongated, a few stacks of rough endoplasmic reticulum, and scanty microtubules and clear vesicles. The second element consisted of innumerable cellular processes. Some of these were elongated and formed stacks connected by symmetric or asymetric adhesive plaque junctions. Others had shorter "neck" containing microtubules extending into bulbous extensions. Dense-cored vesicles were occasionally observed, both in the cytoplasm of neoplastic cells and within processes. In one cell, cross-sectioned annulate lamellae were found. In the cytoplasm of a few cells, unusual inclusions reminiscent of ribosome-lamellae resembled "laboratory tubes" with cone-like endings. At higher power, walls of the "tubes" resolved into layered structures composed of several laminae; between these, ribosome-like structures were visible. The authors conclude that OLC exhibit clear-cut characteristics of neuronal cells and not true oligodendocytes.

Membrane-bound paracrystalloid structures in alveolar rhabdomyosarcoma

We report here a case of an alveolar rhabdomyosarcoma in a 25-year-old woman. Ultrastructural examination revealed a few periodical membrane-bound crystalloids, similar to those regarded as specific for alveolar soft-part sarcoma. Our study provides evidence supporting a myogenic origin of those periodic structures, and simultaneously a myogenic origin of alveolar soft-part sarcoma.

Codon 129 polymorphism of the PRNP gene in normal Polish population and in Creutzfeldt-Jakob disease, and the search for new mutations in PRNP gene

Polymorphism at codon 129 of the prion protein gene (PRNP) is implicated both in susceptibility and phenotype of human prion diseases. We characterized the valine and methionine allele frequency at codon 129 in 109 individuals representing the normal Polish population and in 15 Polish CJD cases. The distribution of the genotype was 45% Met/Met, 39% Met/Val, and 16% Val/Val in the control group whereas, of the CJD cases, 73.3% were homozygous for methionine, 13.3% homozygous for valine and 13.3% were heterozygous. The novel missense mutation (ATG-->ACG) at codon 232 was identified in one of the samples with a GSS phenotype.

Apoptosis in relation to neuronal loss in experimental Creutzfeldt-Jakob disease in mice

Apoptosis constitutes a genetically determined process to eliminate superfluous or damaged cells in tissues. Deficiencies in apoptosis regulation are involved in different pathologies including prion diseases. Some experimental studies show that neuronal loss--one of the hallmarks of prion diseases may be accomplished by apoptosis. We evaluated twenty five mice infected experimentally with the Fujisaki strains of CJD and sacrified sequentially in one week intervals. Apoptotic cells in various brain regions were detected by in situ end labelling (TUNEL) and electron microscopy in comparison with neuronal cell loss. The number of labelled cells per brain was very low--from a few labelled cells 6 weeks after inoculation to a maximum of 14 in the terminal stage. The number of neurones counted in 8 selected areas were considerably lower in terminally sick animals (20 and 21 week of incubation period) than in control mice. The mean value of loss of neuronal cells was 32%. The greatest loss (55%) of neurones was noted in the septal nuclei of the paraterminal body and the least lost (16%) in the hypothalamus. Compared to the extensive neuronal loss (30-50%), the number of apoptotic cells detected by in situ end labelling seems to be very low, and the process of neuronal death become more intensive during the progression of the disease.