Hippocampal pathology in progressive supranuclear palsy (PSP): a quantitative study of 8 cases.

OBJECTIVE: To quantify the neuronal and glial cell pathology in the hippocampus and the parahippocampal gyrus (PHG) of 8 cases of progressive supranuclear palsy (PSP). MATERIAL: tau-immunolabeled sections of the temporal lobe of 8 diagnosed cases of PSP. METHOD: The densities of lesions were measured in the PHG, CA sectors of the hippocampus and the dentate gyrus (DG) and studied using spatial pattern analysis. RESULTS: Neurofibrillary tangles (NFT) and abnormally enlarged neurons (EN) were most frequent in the PHG and in sector CA1 of the hippocampus, oligodendroglial inclusions ("coiled bodies") (GI) in the PHG, subiculum, sectors CA1 and CA2, and neuritic plaques (NP) in sectors CA2 and CA4. The DG was the least affected region. Vacuolation and GI were observed in the alveus. No tufted astrocytes (TA) were observed. Pathological changes exhibited clustering, the lesions often exhibiting a regular distribution of the clusters parallel to the tissue boundary. There was a positive correlation between the degree of vacuolation in the alveus and the densities of NFT in CA1 and GI in CA1 and CA2. CONCLUSION: The pathology most significantly affected the output pathways of the hippocampus, lesions were topographically distributed, and hippocampal pathology may be one factor contributing to cognitive decline in PSP.

A quantitative study of the pathological changes in the cerebellum in 15 cases of variant Creutzfeldt-Jakob disease (vCJD).

AIMS: To determine in the cerebellum in variant Creutzfeldt-Jakob disease (vCJD): (i) whether the pathology affected all laminae; (ii) the spatial topography of the pathology along the folia; (iii) spatial correlations between the pathological changes; and (iv) whether the pathology was similar to that of the common methionine/methionine Type 1 subtype of sporadic CJD. METHODS: Sequential cerebellar sections of 15 cases of vCJD were stained with haematoxylin and eosin, or immunolabelled with monoclonal antibody 12F10 against prion protein (PrP) and studied using spatial pattern analysis. RESULTS: Loss of Purkinje cells was evident compared with control cases. Densities of the vacuolation and the protease-resistant form of prion protein (PrP(Sc)) (diffuse and florid plaques) were greater in the granule cell layer (GL) than the molecular layer (ML). In the ML, vacuoles and PrP(Sc) plaques occurred in clusters regularly distributed along the folia with larger clusters of vacuoles and diffuse plaques in the GL. There was a negative spatial correlation between the vacuoles and the surviving Purkinje cells in the ML. There was a positive spatial correlation between the vacuoles and diffuse PrP(Sc) plaques in the ML and GL. CONCLUSIONS: (i) all laminae were affected by the pathology, the GL more severely than the ML; (ii) the pathology was topographically distributed along the folia especially in the Purkinje cell layer and ML; (iii) pathological spread may occur in relation to the loop of anatomical connections involving the cerebellum, thalamus, cerebral cortex and pons; and (iv) there were pathological differences compared with methionine/methionine Type 1 sporadic CJD.

Erythrocyte invasion profiles are associated with a common invasion ligand polymorphism in Senegalese isolates of Plasmodium falciparum.

Plasmodium falciparum parasites use multiple ligand-receptor interactions to invade human erythrocytes. Variant expression levels of members of the PfRh and PfEBA ligand families are associated with the use of different erythrocyte receptors, defining invasion pathways. Here we analyse a major polymorphism, a large sequence deletion in the PfRh2b ligand, and erythrocyte invasion profiles in uncultured Senegalese isolates. Parasites vary considerably in their use of sialic acid-containing and protease-sensitive erythrocyte receptors for invasion. The erythrocyte selectivity index was not related to invasion pathway usage, while parasite multiplication rate was associated with enhanced use of a trypsin-resistant invasion pathway. PfRh2b protein was expressed in all parasite isolates, although the PfRh2b deletion was present in a subset (approximately 68%). Parasites with the PfRh2b deletion were found to preferentially utilize protease-resistant pathways for erythrocyte invasion. Sialic acid-independent invasion is reduced in parasites with the PfRh2b deletion, but only in isolates derived from blood group O patients. Our results suggest a significant role for PfRh2b sequence polymorphism in discriminating between alternative erythrocyte receptors for invasion and as a possible determinant of virulence.

Validation of modelling the radiation exposure due to solar particle events at aircraft altitudes.

Dose assessment procedures for cosmic radiation exposure of aircraft crew have been introduced in most European countries in accordance with the corresponding European directive and national regulations. However, the radiation exposure due to solar particle events is still a matter of scientific research. Here we describe the European research project CONRAD, WP6, Subgroup-B, about the current status of available solar storm measurements and existing models for dose estimation at flight altitudes during solar particle events leading to ground level enhancement (GLE). Three models for the numerical dose estimation during GLEs are discussed. Some of the models agree with limited experimental data reasonably well. Analysis of GLEs during geomagnetically disturbed conditions is still complex and time consuming. Currently available solar particle event models can disagree with each other by an order of magnitude. Further research and verification by on-board measurements is still needed.

An operational approach for aircraft crew dosimetry: the SIEVERT system.

The study of naturally occurring radiation and its associated risk is one of the preoccupations of bodies responsible for radiation protection. Cosmic particle flux is significantly higher on-board the aircraft that at ground level. Furthermore, its intensity depends on solar activity and eruptions. Due to their professional activity, flight crews and frequent flyers may receive an annual dose of some millisieverts. This is why the European directive adopted in 1996 requires the aircraft operators to assess the dose and to inform their flight crews about the risk. The effective dose is to be estimated using various experimental and calculation means. In France, the computerised system for flight assessment of exposure to cosmic radiation in air transport (SIEVERT) is delivered to airlines for assisting them in the application of the European directive. This professional service is available on an Internet server accessible to companies with a public section. The system provides doses that consider the routes flown by aircraft. Various results obtained are presented.

Progressive supranuclear palsy (PSP): a quantitative study of the pathological changes in cortical and subcortical regions of eight cases.

In eight cases of progressive supranuclear palsy (PSP), neurofibrillary tangles (NFT) were numerous in the substantia nigra (SN), red nucleus (RN), locus caeruleus (LC), pontine nuclei (PN), and inferior olivary nucleus (ION) and abnormally enlarged neurons (EN) in the ION, LC and PN. Loss of Purkinje cells was evident in the cerebellum. Tufted astrocytes (TA) were abundant in the striatum, SN and RN and glial inclusions ('coiled bodies') (GI) in the midbrain (SN, RN) and pons (LC). Neuritic plaques were frequent in one case. NFT, GI, and TA densities were uncorrelated in most areas. NFT and EN densities were positively correlated in the midbrain and surviving neurons and disease duration in several areas. These results suggest: 1) predominantly subcortical pathology in PSP with widespread NFT while TA and GI have a more localized distribution, 2) little correlation between neuronal and glial pathologies, and 3) shorter duration cases may be more likely to develop cortical pathology.

Familial prion disease in a Hungarian family with a novel 144-base pair insertion in the prion protein gene.

About 15% of human prion diseases are inherited, and are associated with point or insertional mutations of the prion protein gene (PRNP). Four families with six octapeptide repeat insertions (OPRI) in the PRNP gene have been described in the literature so far. Here we report two cases in a Hungarian family with a new six OPRI (R1R2R2R3R2R3gR3R2R2R3R4) in the PRNP gene. The clinical features (progressive ataxia, dementia and anosmia), the age of onset and the duration of disease were almost identical. In addition to the cerebellar and parahippocampal pathological changes already described, we also found deposits of pathological prion protein in the olfactory system.

Multiple system atrophy (MSA): topographic distribution of the alpha-synuclein-associated pathological changes.

To study the topographic distribution of the pathology in multiple system atrophy (MSA). Pattern analysis was carried out using alpha-synuclein immunohistochemistry in 10 MSA cases. The glial cytoplasmic inclusions (GCI) were distributed randomly or in large clusters. The neuronal inclusions (NI) and abnormal neurons were distributed in regular clusters. Clusters of the NI and abnormal neurons were spatially correlated whereas the GCI were not spatially correlated with either the NI or the abnormal neurons. The data suggest that the GCI represent the primary change in MSA and the neuronal pathology develops secondary to the glial pathology.

Radiation doses potentially received on-board aeroplanes during recent solar particle events.

Because the doses received on-board aeroplanes are now monitored to fulfil legal requirements in some countries, including the European Community, the models to calculate doses received during solar events have left their purely academic status to become a part of operational systems as well. The present work considers parameters of importance to determine the doses received during solar events: spectral characteristics of the solar particles and anisotropy of primary particles and their variations in the course of the Ground Level Enhancement (GLE). Precise determination of both, using all the information available from the worldwide neutron monitor network, being a long process, simpler methods are proposed to calculate rigidity spectrum exponent and to correct the models for anisotropy. A recent GLE of large intensity, having occurred on 20 January 2005, is used both as an example of an important event and because the necessary data were collected within a few days, showing that the above methods, in addition to their own interest, have also an operational potential.

Multiple system atrophy: laminar distribution of the pathological changes in frontal and temporal neocortex--a study in ten patients.

OBJECTIVE: To determine the distribution of the pathological changes in the neocortex in multiple-system atrophy (MSA). METHOD: The vertical distribution of the abnormal neurons (neurons with enlarged or atrophic perikarya), surviving neurons, glial cytoplasmic inclusions (GCI) and neuronal cytoplasmic inclusions (NI) were studied in alpha-synuclein-stained material of frontal and temporal cortex in ten cases of MSA. RESULTS: Abnormal neurons exhibited two common patterns of distribution, viz., density was either maximal in the upper cortex or a bimodal distribution was present with a density peak in the upper and lower cortex. The NI were either located in the lower cortex or were more uniformly distributed down the cortical profile. The distribution of the GCI varied considerably between gyri and cases. The density of the glial cell nuclei was maximal in the lower cortex in the majority of gyri. In a number of gyri, there was a positive correlation between the vertical densities of the abnormal neurons, the total number of surviving neurons, and the glial cell nuclei. The vertical densities of the GCI were not correlated with those of the surviving neurons or glial cells but the GCI and NI were positively correlated in a small number of gyri. CONCLUSION: The data suggest that there is significant degeneration of the frontal and temporal lobes in MSA, the lower laminae being affected more significantly than the upper laminae. Cortical degeneration in MSA is likely to be secondary to pathological changes occurring within subcortical areas.

Forbush decrease effects on radiation dose received on-board aeroplanes.

Doses received on-board aeroplanes during deep Forbush decreases (FDs) have been recently measured and published. Using an operational model of dose calculation, the effects on aviation dose of the FDs observed from 1981 to 2003 using neutron monitors are studied and a simplified method to estimate dose variations from galactic cosmic ray variations during FDs is derived.

Quantitative analysis of tau isoform transcripts in sporadic tauopathies.

A number of neurodegenerative diseases, including Alzheimer's disease (AD), are characterized by intraneuronal accumulation of the tau protein. Some forms of FTDP-17 are caused by mutations in the tau gene affecting exon 10 splicing. Therefore, dysregulation of tau pre-mRNA splicing may be a contributing factor to sporadic tauopathies. To address this question, we devised a real-time RT-PCR strategy based on the use of a single fluorogenic probe to evaluate the ratio between tau isoforms containing or lacking exon 10 (4R/3R ratio) in post-mortem brain samples. We found a two- to six-fold increase in the 4R/3R ratio in cases of FTDP-17 linked to a splice site mutation, hence confirming the validity of the strategy. The difference in the 4R/3R ratio in the superior temporal and superior frontal gyri between AD and control brains was not statistically significant. Similarly, there was no significant difference in the 4R/3R ratio between Pick's disease cases and controls, indicating that the predominance of tau3R protein in PiD reflects post-translational modifications of specific isoforms. This study indicates that post-translational events are likely to be the main factors controlling tau isoform composition in sporadic tauopathies and highlights the benefit of quantitative RT-PCR in the assessment of splicing abnormalities in tauopathies.

Size frequency distribution of prion protein (PrP) aggregates in variant Creutzfeldt-Jakob disease (vCJD).

The frequency distribution of aggregate size of the diffuse and florid-type prion protein (PrP) plaques was studied in various brain regions in cases of variant Creutzfeldt-Jakob disease (vCJD). The size distributions were unimodal and positively skewed and resembled those of beta-amyloid (A beta) deposits in Alzheimer's disease (AD) and Down's syndrome (DS). The frequency distributions of the PrP aggregates were log-normal in shape, but there were deviations from the expected number of plaques in specific size classes. More diffuse plaques were observed in the modal size class and fewer in the larger size classes than expected and more florid plaques were present in the larger size classes compared with the log-normal model. It was concluded that the growth of the PrP aggregates in vCJD does not strictly follow a log-normal model, diffuse plaques growing to within a more restricted size range and florid plaques to larger sizes than predicted.

A quantitative study of the pathological changes in ten patients with multiple system atrophy (MSA).

The densities of the glial cytoplasmic inclusions (GCI), neuronal inclusions (NI), and abnormal neurons were studied in the frontal cortex, hippocampus, cerebellum, basal ganglia and areas of the pons and medulla in 10 cases of multiple system atrophy (MSA). GCI density was greater in the substantia nigra and globus pallidus compared with the frontal cortex and hippocampus. Abnormal neurons were most abundant in the frontal cortex, substantia nigra, and inferior olivary nucleus. NI and abnormal neuron densities were positively correlated in the globus pallidus but negatively correlated in the hippocampus. The NI and GCI were only positively correlated in the pons. GCI in the pons and inferior olivary nucleus, NI in the substantia nigra, and abnormal neurons in the frontal cortex varied significantly between cases. The MSA cases did not cluster according to disease subtype. The data suggest that: 1) the greatest densities of pathological changes occur in the substantia nigra and globus pallidus, 2) density of the GCI is unrelated to that of the NI, and 3) there is overlapping pathology between the various subtypes of MSA.

Spatial correlation between the vacuolation, prion protein, deposition and surviving neurons in patients with Creutzfeldt-Jakob disease (vCJD).

The histological features of cases of variant Creutzfeldt-Jakob disease (vCJD) are often distributed in the brain in clusters. This study investigated the spatial associations between the clusters of the vacuoles, surviving neurons, and prion protein (PrP) deposits in various brain areas in 11 cases of vCJD. Clusters of vacuoles and surviving neurons were positively correlated in the cerebral cortex but negatively correlated in dentate gyrus. Clusters of the florid and diffuse type of PrP deposit were not positively correlated with those of either the vacuoles or the surviving neurons although a negative correlation was observed between the florid plaques and surviving neurons in some cortical areas. Clusters of florid and diffuse deposits were either negatively correlated or uncorrelated. These data suggest: 10 that clusters of vacuoles in the cerebral cortex are associated with the presence of surviving neuronal cell bodies, 2) that clusters of vacuoles are not spatially related to those of the PrP deposits, and 3) different factors are involved in the pathogenesis of the florid and diffuse PrP deposits.

History of the solar particle event radiation doses on-board aeroplanes using a semi-empirical model and Concorde measurements.

Measurements during solar particle events with dosemeters flying permanently on-board Concorde are used to develop a semi-empirical model, called SiGLE. The model is intended to calculate, for a given flight plan, the dose equivalent received during a solar particle event observed with ground-based neutron monitors. It is successfully in operation in the SIEVERT computerised system intended to improve monitoring of radiation dose received by aircrews, in application to a European Directive. The semi-empirical model is applied to evaluate, for most exposed routes, the radiation doses corresponding to the GLEs observed since 1942 with ion chambers or neutron monitors. The results for the largest GLEs observed in the past are discussed in terms of radiation risk, and guidelines are suggested concerning possible alerts to the aeroplanes in case of events of exceptional magnitude.

Differences in the density and spatial distribution of florid and diffuse plaques in variant Creutzfeldt-Jakob disease (vCJD).

OBJECTIVE: To determine whether in cases of variant Creutzfeldt-Jakob disease (vCJD), the florid-type plaques are derived from the diffuse plaques or whether the 2 plaque types develop independently. MATERIAL: Blocks of frontal, parietal, occipital and temporal neocortex and cerebellar cortex from 11 cases of vCJD. METHOD: The density, distribution and spatial pattern of the florid and diffuse plaques were determined in each brain region using spatial pattern analysis. RESULTS: The density of the diffuse plaques was significantly greater than that of the florid plaques in most areas. The ratio of the diffuse to florid plaques varied between brain regions and was maximal in the molecular layer of the cerebellum. The densities of the florid and diffuse plaques were positively correlated in the parietal cortex, occipital cortex, the inferior temporal gyrus and the dentate gyrus. Plaque densities were not related to disease duration. In the cerebral cortex, the diffuse plaques were more commonly evenly distributed or occurred in large clusters along the cortex parallel to the pia mater compared with the florid plaques which occurred more frequently in regularly distributed clusters. CONCLUSION: The florid plaques may not be derived from the diffuse plaques, the 2 plaque types appearing to develop independently with unique factors involved in their pathogenesis.

Does the neuropathology of human patients with variant Creutzfeldt-Jakob disease reflect haematogenous spread of the disease?

To test the hypothesis that the distribution of the pathology in variant Creutzfeldt-Jakob disease (vCJD) represents haematogenous spread of the disease, we studied the spatial correlation between the vacuolation, prion protein (PrP) deposits, and the blood vessel profiles in the cerebral cortex, hippocampus, dentate gyrus, and cerebellum of 11 cases of the disease. In the majority of areas, there were no significant spatial correlations between either the vacuolation or the diffuse type of PrP deposit and the blood vessels. By contrast, a consistent pattern of spatial correlation was observed between the florid PrP deposits and blood vessels mainly in the cerebral cortex. The frequency of positive spatial correlations was similar in different anatomical areas of the cerebral cortex and in the upper compared with the lower laminae. Hence, with the exception of the florid deposits, the data do not demonstrate a spatial relationship between the pathological features of vCJD and blood vessels. The spatial correlation of the florid deposits and blood vessels may be attributable to factors associated with the blood vessels that promote the aggregation of PrP to form a condensed core rather than reflecting the haematogenous spread of the disease.

Neuronal loss in familial frontotemporal dementia with ubiquitin-positive, tau-negative inclusions.

The neuronal density in the frontal, temporal, and parietal lobes was determined in nine cases of familial frontotemporal dementia with ubiquitin-positive, tau-negative inclusions (FTDU). The mean age at onset was 56.9 +/- 2.2 years and the duration of disease was 6.7 +/- 0.5 years. The mean age at death was 63.6 +/- 2.2 years. There was substantial loss (34%) of brain weight (877 +/- 73 g) in the familial cases in comparison with 10 normal aged controls (1326 +/- 50 g, P < 0.001). All of the familial FTDU cases showed atrophy of the frontal, temporal, and parietal lobes; neuronal loss; vacuolation in superficial laminae; reactive astrocytosis; and ubiquitin-positive, tau-negative intracytoplasmic and intranuclear inclusions and dystrophic neurites in varying sites and numbers. Neuronal loss was estimated in nine cases of familial FTDU and in 10 aged controls using a stereological probe, the optical "disector," and a computerized stereology system (CAST-Grid, Olympus, Denmark). There was a significant reduction in neuronal density in the frontal lobe (22.3 +/- 3.8 x 10(3)/mm(3)) of familial FTDU in comparison to aged controls (33.1 +/- 1.7 x 10(3) per mm(3), P < 0.05). An estimate of the relative numbers of neurons was calculated by multiplying the numerical density by the cortical thickness, which showed a striking loss of neurons of 56% in the frontal lobe, 52% loss in the temporal lobe, and a 49% loss in the parietal lobe of familial FTDU when compared to controls. This study shows that familial FTDU has profound focal neuronal loss in multiple association areas that relate to the clinical symptoms characteristic of the disease.