Ultrastructural changes in the optic nerves of rodents with experimental Creutzfeldt-Jakob Disease (CJD), Gerstmann-Sträussler-Scheinker disease (GSS) or scrapie.

This report describes the ultrastructural changes in the optic nerves of (1) hamsters infected with the Echigo-1 strain of Creutzfeldt-Jakob disease (CJD), (2) hamsters infected with the 263K or 22C-H strain of scrapie, and (3) mice infected with the Fujisaki strain of Gerstmann-Sträussler-Scheinker disease (GSS). Vacuolation of myelinated fibres was present in the myelin sheaths, with splitting of myelin lamellae. These vacuoles contained typical secondary vacuoles and curled membrane fragments. Myelinated fibre vacuolation was also accompanied by an exuberant cellular reaction consisting of macrophages containing numerous mitochondria, abundant rough endoplasmic reticulum, and secondary lysosomes filled with digested myelin debris and other electron-dense material. Within macrophages, myelin fragments undergoing active digestion, lyre-like bodies and paracrystalline inclusions were frequently noted. Astrocytes and their processes were prominent; glial filaments and many mitochondria were readily detected. Proliferation of inner mesaxons was observed. Cross-sectional profiles of innumerable myelinated fibres contained membranous organelles continuous with the inner lamellae of the oligodendroglial cells. The proliferations of inner mesaxons formed whorls and loops, and intrusion of the membranous tongue of the inner mesaxon into the axoplasm was occasionally observed; dystrophic neurites were relatively numerous. In mice infected with the Fujisaki strain of GSS, fibres had undergone demyelination with stripping of the myelin lamellae, while others showed vesicular myelin degeneration.

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.

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.

[Prions, epidemic of Creutzfeldt-Jakob variant disease and global emergency]. / Priony, epidemia wariantu choroby Creutzfeldta-Jakoba i zagrozenie globalne.

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.

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.

Protective role of beta-chemokines associated with HIV-specific Th responses against perinatal HIV transmission.

To examine the protective role of cellular immunity in the vertical transmission of HIV, we analyzed HIV-specific IL-2 and CTL responses, as well as beta-chemokine expression in HIV-infected and uninfected infants of HIV+ mothers. Our results showed that HIV envelope (env) peptide-specific IL-2 responses associated with beta-chemokine production were detectable at birth in the majority of uninfected infants of HIV+ mothers. The responses falling to background before the infants were 1 yr old were rarely associated with HIV-specific CTL activity. Conversely, HIV-specific Th and CTL cellular responses were absent at birth in HIV-infected infants. Infants with AIDS-related symptoms exhibited undetectable or very low levels of HIV-specific cellular immunity during the first year of life, whereas those with a slowly progressive disease showed evidence of such immunity between their second and ninth month. The latter group of infected infants tested negative for plasma HIV RNA levels shortly after birth, suggesting lack of intrauterine exposure to HIV. The presence of HIV-specific Th responses at birth in uninfected newborns of HIV+ mothers, but absence of such activities in HIV-infected infants without evidence of intrauterine HIV infection, suggests that in utero development of HIV-specific Th responses associated with beta-chemokines could mediate nonlytic inhibition of infection during vertical transmission of HIV.

Molecular analysis of PRNP gene in Polish population and in Creutzfeldt-Jakob disease.

In our study we have examined allelic variation of codon 129 among the Polish population as well as Polish and Dutch CJD cases. The open reading frame of the PrP gene was amplified using the polymerase chain reaction (PCR). PCR product was digested with Nsp I and Mae II endonucleases and separated by 2% agarose gel electrophoresis and, finally, sequenced by the Sanger dideoxy-mediated chain-termination method. To obtain population data we have screened 109 unrelated Polish adults. There were 45% of methionine homozygotes, 16% of valine homozygotes and 3% of heterozygotes. Among Polish CJD cases, 75% were methionine homozygous, 12.5% were valine homozygous and 12.5% were heterozygous, whereas among Dutch CJD cases it was 29% of Met/Met and 71% of Met/Val genotypes.

A case of sporadic Creutzfeldt-Jakob disease with a Gerstmann-Sträussler-Scheinker phenotype but no alterations in the PRNP gene.

We report here an unusual sporadic case of Creutzfeldt-Jakob disease (CJD) characterized by an abundance of prion protein (PrP)-immunopositive kuru and multicentric but not florid plaques. Molecular genetic analysis of the PRNP open reading frame region spanning codons 8-221 was performed. Neither deletion nor insertion mutations were detected in the repeat area of the PRNP. No pathogenic mutation was found in the sequenced region between codon 108-221. Restriction analysis of the amplified fragment using restriction endonucleases DdeI, PvuII and AluI did not show any of the previously described pathogenic mutations at codon 102, 105, and 117 associated with Gerstmann-Sträussler-Scheinker (GSS). The patient was heterozygous for the methionine/valine coding triplet at polymorphic codon 129 of the PRNP gene by sequence, restriction endonuclease analysis and hybridization with allele-specific nucleotides. Furthermore, hybridization with 32P-labeled allele-specific oligonucleotides confirmed the absence of pathogenic mutations at codons 102, 200 and 178. Such a case may present a missing "link" between sporadic CJD and familial GSS.

Progressive multifocal leukoencephalopathy (PML) and cerebral toxoplasmosis in an adult patient, with no symptoms of underlying immunosuppressing illness.

We present a case of the coincidence of progressive multifocal leukoencephalopathy (PML) and central nervous system (CNS) toxoplasmosis in an adult patient, without a detectable cause of cell-mediated immunity impairment. The proper diagnosis was made postmortem on the basis of histological changes typical of both pathological processes. PML was characterized by the presence of subcortical focal demyelination, containing enlarged, densely basophilic oligodendrocyte nuclei, often with intranuclear inclusion, and bizarre astrocytes, mimicking neoplastic cells. PML was confirmed by detecting numerous papova virus particles in oligo- and astroglial nuclei by thin-section electron microscopy. Cerebral toxoplasmosis was characterized by the presence of multiple well-circumscribed necrotizing abscesses. Numerous Toxoplasma gondii (T. gondii) cysts and free, non-encysted protozoan parasites were found among the inflammatory infiltrates. The diagnosis of cerebral toxoplasmosis was further confirmed by immunocytochemistry. In order to detect putative immunosuppressive background underlying both pathological processes, HIV infection was taken into consideration, however, no histopathological changes indicative of AIDS either in the CNS or in the peripheral organs were eventually found. Moreover no HIV provirus genome was identified in the formalin-fixed, paraffin embedded brain tissue by the polymerase chain reaction (PCR). Current view on the selected aspects of the pathogenesis of both disorders were discussed.

The effect of epitope variation on the profile of cytotoxic T lymphocyte responses to the HIV envelope glycoprotein.

To address the relationship between viral and host factors during HIV infection, we analyzed the effect of viral mutations on T cell responses in seropositive, asymptomatic HLA-A2+ individuals using four envelope (env)-specific peptides with the HLA-A*0201 binding motif. We showed that the natural sequence variation was frequent within epitopes located in the C-terminal region of the env glycoprotein and was largely responsible for a lower env-specific cytotoxic T lymphocyte (CTL) activity in the peptide-stimulated cultures. The highest CTL responses in vitro were induced with conserved epitopes D1 and 4.3 that mapped to the N-terminal region of the env glycoprotein. These peptides exhibited high binding affinity for HLA-A*0201 molecules and stimulated CD8+ T cells of relatively limited TCR Vbeta chain repertoire. Decreased CTL activities to the D1 epitope were observed in the absence of any detectable viral mutation, and were associated with lower proliferative responses and expression of the CD28 antigen. Results of this study demonstrate that the degree of sequence variation within a stimulatory epitope of the viral quasispecies, as well as proliferative potential of the effector cells, are among the factors underlying decreased CTL activity in HIV-infected patients. These experiments also provide evidence that the D1 peptide might be useful for the development of vaccines and immune-based therapy.

Parvovirus particles in a fetal-heart with myocarditis: ultrastructural and immunohistochemical study.

We report on the occurrence of parvovirus particles and VP1 (84 kDa) and VP2 (58 kDa) viral antigens in the heart of a case of fatal myocarditis in a fetus of a 26 year old women. Numerous cells containing intranuclear inclusions were identified within the blood vessels of the heart in a close apposition to muscle fibers. These cells were characterized by plentiful mitochondria and were consistent with erythroblasts. Typically, inclusions consisted of electrondense marginated chromatin and granular and amorphous "cores". At higher magnification, parvovirus particles, approximately 23 nm in diameter, were visualized either as relatively small clusters or forming large paracrystalline arrays. Virus buds were never observed. In addition, unusual membrane proliferation was seen. These findings support a notion that parvovirus may invade the fetal heart.

Microwave treatment enhances the immunostaining of amyloid deposits in both the transmissible and non-transmissible brain amyloidoses.

The immunolocalization of amyloid deposits containing either protease-resistant prion protein (PrP) or amyloid beta protein (A beta) in the brains of patients with transmissible or non-transmissible cerebral amyloidoses has been greatly facilitated by the pretreatment of tissue sections with concentrated formic acid. We have investigated whether microwave processing of formalin-fixed tissue sections would obviate the need for formic acid pretreatment. Exposure of brain sections to microwaves, even for periods as brief as 1 sec, greatly enhanced the immunostaining of PrP and A beta amyloid deposits in both the transmissible and non-transmissible brain amyloidoses. Microwaving for 1 min yielded staining intensities similar to that following pretreatment with concentrated formic acid for 10 min. Moreover, the combination of formic acid pretreatment and microwave processing resulted in an even more intense staining of amyloid deposits. Microwave processing, which is easy to perform and comparatively inexpensive, makes exposure to the potentially toxic fumes of formic acid unnecessary.

Diagnosis of Alzheimer's disease with commercially available anti-beta peptide (beta A4) antibodies following microwave oven pretreatment.

Alzheimer's disease (AD), the most common presenile dementia is underdiagnosed in Poland, thus every attempt to make the frequency of this diagnosis approaching standards of Western countries should be recommended. Deposits of beta A4 amyloid in a form of amyloid (senile) plaques, diffuse amyloid deposits and congophilic angiopathy is central to the pathogenesis of AD. These amyloid deposits are virtually invisible in routine pathological stainings like HE but may be visualized with Bielschowsky silver impregnation, other metallic impregnations, and following Thioflavine S or Congo red stainings. We report here that amyloid deposits are as easily immunolabeled with commercially available antibodies against beta A4 (DAKO) and such a staining was greatly enhanced by microwave oven pretreatment. In all cases of AD, the diagnosis could be easily made using either 4GM or commercial DAKO anti-beta A4 antibodies following pretreatment with formic acid or processing in microwave oven. Pretreatment in microwave oven even for only one second was already sufficient to visualize beta A4-immunopositive plaques while after 5 second the intensity of staining approached that obtained after formic acid pretreatment.

Expression of p53-protein, epidermal growth factor receptor (EGFR) and proliferating cell antigens in human gliomas.

Paraffin-embedded surgical specimens from 56 human astrocytomas (8 pilocytic [I degree] astrocytomas, 9 low grade [II degrees] fibrillary astrocytomas, 9 high grade [III degrees] astrocytomas and 30 glioblastomas) were immunostained with the anti-PCNA, anti-p53, anti-Ki-67 and anti EGFR antibodies. Approximately 41% of all cases were p53 protein-positive while 23% were EGFR positive. Five cases (8.9%) were positive for both p53 protein and EGFR. Low grade gliomas showed low PCNA LI while high PCNA LI was observed in high grade gliomas. The same trend was observed with anti-Ki-67 antibodies but the proportion of Ki-67 immunolabelled cells was always much lower. In conclusion, we found two populations of astrocytic tumors with EGFR and with p53 protein overexpression but no dependence between p53 immunoreactivity and PCNA or Ki-67 LI.