Immunoreactivity of the monoclonal antibody F89/160.1.5 for the human prion protein

Monoclonal antibodies (Mab) to the prion protein (PrP) have been critical to the neuropathological characterisation of PrP-related diseases in human and animals. Although PrP is highly evolutionary conserved, there is some sequence divergence among species. We have analysed the F89/160.1.5 Mab raised against the bovine prion protein for immunoreactivity with the human prion protein. The antibody recognised the IHFG epitope of the prion protein. An analysis of the Swiss Prot database confirmed conservation of the epitope in humans. Further immunohistochemical (IHC) analysis showed a highly sensitive (final concentration 55 ng/ml) and specific antibody for prion detection in humans. The observed immunoreactivity of the prion protein did not differ from that observed after staining with the well-known 3F4 (Senetek) monoclonal antibody.

Behavioral disturbances without amyloid deposits in mice overexpressing human amyloid precursor protein with Flemish (A692G) or Dutch (E693Q) mutation

The contribution of mutations in the amyloid precursor protein (APP) gene known as Flemish (APP/A692G) and Dutch (APP/E693Q) to the pathogenesis of Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis of the Dutch type, respectively, was studied in transgenic mice that overexpress the mutant APP in brain. These transgenic mice showed the same early behavioral disturbances and defects and increased premature death as the APP/London (APP V717I), APP/Swedish (K670N, M671L), and other APP transgenic mice described previously. Pathological changes included intense glial reaction, extensive microspongiosis in the white matter, and apoptotic neurons in select areas of the brain, while amyloid deposits were absent, even in mice over 18 months of age. This contrasts with extensive amyloid deposition in APP/London transgenic mice and less pronounced amyloid deposition in APP/Swedish transgenic mice generated identically. It demonstrated, however, that the behavioral deficiencies and the pathological changes in brain resulting from an impaired neuronal function are caused directly by APP or its proteolytic derivative(s). These accelerate or impinge on the normal process of aging and amyloid deposits per se are not essential for this phenotype.

Decreased Levels of Amyloid-beta 1-42 in Cerebrospinal Fluid of Creutzfeldt-Jakob Disease Patients

Creutzfeldt–Jakob disease (CJD) is a rare neurodegenerative disease caused by the prion protein. In the search for biochemical markers for CJD, cerebrospinal fluid (CSF) of 101 patients was analysed for 14-3-3 protein, hTau-protein and amyloid-beta 1-42 (Abeta_1-42). The 14-3-3 test had a specificity of 91.5% and a sensitivity of 84%. The hTau test resulted in 95% specificity and 74% sensitivity, when a cut-off of 1530 pg/ml was used. Abeta_1-42 detection in CSF of 29 probable or definite CJD patients revealed significantly decreased values (p=0.01) compared to a group of 22 neurological controls. In the CJD patients a mean of 319+/-102 pg/ml was found. In the neurological control group a mean of 553+/-268 pg/ml was observed. In patients with a false positive 14-3-3 test (n=5) a mean of 716+/-441 pg/ml was found. We conclude that determination of Abeta_1-42 levels in CSF can be useful for identifying false positive 14-3-3 results in suspected CJD patients. We also compared the presence of senile plaques and the Abeta_1-42 levels in CSF of CJD patients. No clear correlation between them was found in this series. This signifies that the deceased Abeta_1-42 levels in CSF are not just due to plaque retention but that other mechanisms must also play a role.

Antigen retrieval in prion protein immunohistochemistry

Transmissible spongiform encephalopathies are a group of neurodegenerative diseases occurring in both humans and animals and are most likely caused by prions. Neuropathological confirmation of the clinical diagnosis has been a problem because of the difficulty in epitope retrieval from formalin-fixed, paraffin-embedded brain specimens. Many different protocols for the detection of prions in brain tissue have been used. Thus far, picric and/or formic acid, steam autoclaving at 121C of sections, microwave treatment, and 4 M guanidine thiocyanate treatment have been suggested. The objective of our experiment was to obtain the standard pretreatment(s) resulting in optimal immunostaining. In the experiment, successive tissue slides of brain specimens of several Creutzfeldt-Jakob disease and control patients were stained using different combinations of pretreatments. Using densitometric analysis, several well-defined locations per section were examined and prion immunostaining was quantified. The results showed that autoclaving is necessary for antigen retrieval and cannot be substituted by microwave treatment. The best results were obtained when the following combination was used in the specified order: 15 min saturated picric acid, 10 min steam autoclaving at 121C, 5 min 88% formic acid, and 2 hr 4 M guanidine thiocyanate at 4C. (J Histochem Cytochem 47:1465-1470, 1999)

Proteolytic processing of presenilin-1 in human lymphoblasts is not affected by the presence of the I143T and G384A mutations

Presenilin-1 (PSEN1) mutations I143T and G384A give rise to severe early onset Alzheimers's disease in two extensively studied Belgian families, AD/A and AD/B. In this study we investigated the influence of the I143T and G384A mutations on PSEN1 proteolytic processing. Hereto we analyzed PSEN1 processing in lymphoblasts by immunodetection with PSEN1-specific antibodies and densitometric analysis of the immunoreactive banding pattern. No differences were observed between presymptomatic mutation carriers, patients or escapees, demonstrating that the PSEN1 mutations I143T and G384A do not alter PSEN1 proteolytic processing in lymphoblasts.

Evidence that Abeta42 plasma levels in presenilin-1 mutation carriers do not allow for prediction of their clinical phenotype

Mutations in the presenilin 1 (PSEN1) gene are an important cause of autosomal dominant Alzheimer's disease (AD). Both in vitro and in vivo experiments showed that PSEN1 mutations increase secretion of amyloid beta42 (Abeta42), the longer and more fibrillogenic isoform of Abeta. We measured secreted Abeta42 in plasma of patients, presymptomatic mutation carriers, and escapees of two extended Belgian early-onset AD families, AD/A and AD/B, with a similar severe phenotype in terms of onset age (mean 35 years), duration of the disease (mean 6.5 years), and pathology. Both families segregate a different missense mutation in PSEN1 located in different parts of the protein: I143T in family AD/A and G384A in family AD/B. A significant increase in Abeta42 concentrations was observed in plasma of mutation carriers in family AD/B, but not in family AD/A. A differential effect of the two PSEN1 mutations on Abeta42 secretion was also detected in conditioned medium of stably transfected HEK293 cells. Both mutations increased Abeta42 secretion significantly; however, the increase was highest for G384A (5.5-fold over wild-type PSEN1), the largest effect observed for missense PSEN1 mutations to date. Although the Abeta42 concentrations measured in vivo and in vitro did not correlate with onset age, a positive correlation was obtained with age in the presymptomatic mutation carriers and a negative correlation with duration of disease in the patients. Our data obtained for PSEN1 mutation carriers suggest that measuring Abeta42 concentrations in plasma will be informative as a diagnostic marker in a limited number of cases.

[Safety measures for handling laboratory specimen and patients with Creutzfeldt-Jakob disease]

Creutzfeldt-Jakob disease (CJD) is a transmissible subacute spongiform encephalopathy that invariably leads to death. The presumed causative agent, the prion protein, is highly resistant to inactivation and has a long incubation period. Physical contact with CJD patients (as in clinical care) entails no risk of transmission. During procedures such as lumbar puncture where contact with infected material is possible, precautions are necessary. Precautions are: the use of gloves, maximal protection of people who come in contact with contaminated tissue (e.g. pathologist and histological laboratory worker) and transportation of samples in a closed and labelled container. For laboratory research the tissue must be submerged in 92-98% formic acid for 1 hour. All used materials and instruments must be decontaminated properly, using for instance NaOH, NaClO, guanidine thiocyanate or steam autoclaving. If adequate precautions are taken contact with contaminated materials can be safe.

Humanization of mouse 5-hydroxytryptamine1B receptor gene by homologous recombination: in vitro and in vivo characterization

We replaced the coding region of the murine 5-hydroxytryptamine (5-HT)1B receptor by the human 5-HT1B receptor using homologous recombination in embryonic stem cells and generated and characterized homozygous transgenic mice that express only the human (h) 5-HT1B receptor. The distribution patterns of h5-HT1B and murine (m) 5-HT1B receptor mRNA and binding sites in brain sections of transgenic and wild-type mice were identical as measured by in situ hybridization histochemistry and radioligand receptor autoradiography. When measured in parallel under identical conditions, the h5-HT1B receptor expressed in mouse brain had the same pharmacological characteristics as that in human brain. Stimulation by 5-HT1B agonists of [35S]guanosine-5'-O-(3-thio)triphosphate binding in brain sections demonstrated the functional coupling of the h5-HT1B receptor to G proteins in mouse brain. In tissue slices from various brain regions, electrically stimulated [3H]5-HT release was not modified by 5-HT1B agonists in tissue from either transgenic and wild-type mice; a 5-HT1B antagonist enhanced electrically stimulated [3H]5-HT release in wild-type mouse brain, but was ineffective in the transgenics. The centrally active 5-HT1A/5-HT1B agonist RU24969 induced hypothermia but did not increase locomotor activity in the transgenic mice. The ineffectiveness of RU24969 in the transgenic mice could be due to the lower affinity of the compound for the h5-HT1B receptor compared with the m5-HT1B receptor. The present study demonstrates a complete replacement of the mouse receptor by its human receptor homolog and a functional coupling to G proteins. However, modulation of [3H]5-HT release could not be shown. Furthermore, behavioral effects were not clearly observed, which may be due to a lack of appropriate tools.

A retrospective study of Creutzfeldt-Jakob disease in Belgium

Using data from Belgian neuropathological archives, completed with the results of a comprehensive study of available medical records, we found 100 patients who fulfilled diagnostic criteria for probable or definite Creutzfeldt-Jakob d1551isease (CJD). Mean age at death was 63 years. The median disease duration was 9 months. Progressive mental deterioration was present in all cases, whereas signs of cerebellar dysfunction and myoclonus were found in approximately 80% of the patients. In 50% of the population, the EEG revealed characteristic abnormalities. Ninety-six patients suffered from the sporadic type of CJD, while 4 suffered from a hereditary form. In our series, we could find no evidence for the new variant, neither for an iatrogenic cause.

Postmortem examination of two fragile X brothers with an FMR1 full mutation

Large expansions of the CGG repeat in the 5' untranslated region of the FMR1 gene are found in patients with the fragile X syndrome. Amplified CGG repeats in FMR1 are unstable and show intergenerational increase from mother to offspring. The exact timing of repeat amplification, however, is unknown. We have compared the extent of CGG expansion in various tissues of this deceased fragile X patient, and found only limited variation in repeat expansion. The repeat was fully methylated in all tissues examined. Therefore, no evidence for extensive mitotic expansion of the CGG repeat during fetal or postnatal life of a fragile X patient was found, in contrast to dynamic mutations caused by CAG/CTG repeat expansion. Extensive pathological examination of this patient and his affected brother revealed no evidence for specific abnormalities relevant to fragile X syndrome; cerebellar hypoplasia, which has been reported in this disorder, was not evident in either patient.

Improved discrimination of AD patients using beta-amyloid(1-42) and tau levels in CSF

OBJECTIVE

To evaluate CSF levels of beta-amyloid(1-42) (Abeta42) alone and in combination with CSF tau for distinguishing AD from other conditions.

METHODS

At 10 centers in Europe and the United States, 150 CSF samples from AD patients were analyzed and compared with 100 CSF samples from healthy volunteers or patients with disorders not associated with pathologic conditions of the brain (CON), 84 patients with other neurologic disorders (ND), and 79 patients with non-Alzheimer types of dementia (NAD). Sandwich ELISA techniques were used on site for measuring Abeta42 and tau.

RESULTS

Median levels of Abeta42 in CSF were significantly lower in AD (487 pg/mL) than in CON (849 pg/mL; p = 0.001), ND (643 pg/mL; p = 0.001), and NAD (603 pg/mL; p = 0.001). Discrimination of AD from CON and ND was significantly improved by the combined assessment of Abeta42 and tau. At 85% sensitivity, specificity of the combined test was 86% (95% CI: 81% to 91%) compared with 55% (95% CI: 47% to 62%) for Abeta42 alone and 65% (95% CI: 58% to 72%) for tau. The combined test at 85% sensitivity was 58% (95% CI: 47% to 69%) specific for NAD. The APOE e4 gene load was negatively correlated with Abeta42 levels not only in AD but also in NAD.

CONCLUSIONS

The combined measure of CSF Abeta42 and tau meets the requirements for clinical use in discriminating AD from normal aging and specific neurologic disorders.

Determination of growth fraction and cell density to evaluate the potential growth of human oligodendroglial and astrocytic tumours

The object of this work was

PURPOSE

to develop a methodology that enables net tumour growth, a balance between actual tumour growth and tumour cell loss, to be approximately evaluated.

METHODS

The methodology proposed relies on detecting the growth fraction immunohistochemically by means of MIB-1 antibody labelling combined with cell density determination, carried out on 5-microm-thick Feulgen-stained histological sections with computer-assisted microscopy. The series investigated included 25 oligodendrogliomas (OLG-II), 9 anaplastic oligodendrogliomas (OLG-III). 13 astrocytomas (AST), 14 anaplastic astrocytomas (ANA) and 8 mixed oligoastrocytomas (OLG-AST).

RESULTS

The results show that the biological characteristics of some cases were in total accordance with their histopathological diagnoses. This was the case for the "weakly proliferating weakly dense" OLG-II and AST-II tumours, and for the "highly proliferating highly dense" OLG-III and AST-III ones. In contrast, the biological characteristics of some cases seemed to contradict the histopathological case labels. This was the case for the "highly proliferating highly dense" OLG-II and AST-II tumours, the biological aggressiveness of which would be undervalued on the basis of the morphology-based grading system alone, and also for the "weakly proliferating weakly dense" OLG-III and AST-III tumours, the aggressiveness of which would be overvalued.

CONCLUSIONS

Combining the determinations of the MIB-1 and the cell density variables appears to be satisfactory in terms of the cell kinetic characterization of glial tumours as a complement to the prognostic information given by a morphology-based grading system alone.

Creutzfeldt-Jakob disease and blood transfusion

Experimental data suggest that blood components from patients with CJD may carry infectivity. However, most of the studies have been made on the classic form of CJD. Further studies are needed to discern whether infectivity levels in blood from patients with the nvCJD differ from those with the classic form. Possibility of transmission of CJD by blood or blood products can not be excluded and therefore adequate surveillance should be implemented. People who have been exposed to contaminated blood should be followed, while recommendations are being adapted according to new scientific data on infectivity.

Cervical myelopathy due to rheumatoid arthritis. Case report and review of the literature

We present the case report of a 62 year-old female suffering from destructive rheumatoid arthritis (RA) for more than 20 years. She had complaints of progressive gait impairment and numbness in hands and feet. Neurological examination showed an unstable gait and pyramidal tract signs. Anterior atlantoaxial subluxation with pannus formation and cervical myelopathy were demonstrated using conventional X-ray studies and MRI. She was conservatively treated with a soft collar. Treatment with methotrexate and an intensive gait revalidation program were started. RA commonly involves the cervical spine, usually in advanced systemic disease after a mean delay of 16 years. Subluxations of the cervical spine are found in 43 to 86%, 50% of these patients are asymptomatic. The reported rate of neurological impairment due to cervical instability ranges from 7 to 58%. The three most common lesions resulting from cervical RA are atlantoaxial subluxation (50 to 70%), subaxial subluxation (15 to 25%) and cranial settling (20%). It is important to differentiate between cranial settling and atlantoaxial instability, as the latter may have a more benign history with less than 20% showing progressive instability. Cranial settling progresses in 35 to 50% of patients. The commonest presenting features of rheumatoid cervical myelopathy are isolated sensory symptoms. Most patients were found to have multiple neurological deficits once the myelopathy was diagnosed. A mean delay of 31 weeks between the first symptom and the diagnosis of the myelopathy is reported. The sensory symptoms are often misinterpreted as being due to entrapment neuropathy or rheumatoid peripheral neuropathy. Radiographic analysis indicates that the posterior atlantoodontoid interval (< or = 14 mm) is an important parameter that shows excellent correlation with the severity of paralysis.

Presenile Alzheimer dementia characterized by amyloid angiopathy and large amyloid core type senile plaques in the APP 692Ala-->Gly mutation

Mutations at codons 717 and 670/671 in the amyloid precursor protein (APP) are rare genetic causes of familial Alzheimer's disease (AD). A mutation at codon 693 of APP has also been described as the genetic defect in hereditary cerebral hemorrhage with amyloidosis of the Dutch type (HCHWA-D). We have reported a APP692Ala-->Gly (Flemish) mutation as a cause of intracerebral hemorrhage and presenile dementia diagnosed as probable AD in a Dutch family. We now describe the post-mortem examination of two demented patients with the APP692 mutation. The neuropathological findings support the diagnosis of AD. Leptomeningial and parenchymal vessels showed extensive deposition of Abeta amyloid protein. Numerous senile plaques consisted of large Abeta amyloid cores, often measuring more than 30 microm in diameter and were surrounded by a fine meshwork of dystrophic neurites. In addition, there were a large number of paired helical filaments in pyramidal neurons and dystrophic neurites. Our findings show that the APP692 mutation leads to morphological abnormalities that are similar to AD, but the morphology of senile plaques is clearly distinct from that described in sporadic and chromosome 14-linked AD patients, in patients with APP717 mutations causing familial, presenile AD and in patients with the APP693 mutation causing HCHWA-D.

Characterization of astroglial versus oligodendroglial phenotypes in glioblastomas by means of quantitative morphonuclear variables generated by computer-assisted microscopy

The current WHO classification places glioblastomas in the astrocytoma category. However, whether or not glioblastomas also show oligodendroglial differentiation remains a matter of controversy. This study investigates, at the morphonuclear level, the hypothesis that some glioblastomas (GBMs) may also represent the ultimate level of malignancy in the oligodendroglial lineage. Using a series of 164 GBMs, we sought to ascertain whether any of these GBMs exhibited phenotypical characteristics that were more closely related to oligodendroglial lineages than astrocytic lineages. Phenotypical features were quantitatively determined by means of the computer-assisted microscope analysis of Feulgen-stained nuclei, a process that made it possible to quantitatively describe the patterns of the cell nuclei (and, more specifically, of their chromatin) through 16 variables, and the distribution of the nuclear DNA content (DNA ploidy) through 8 variables. The phenotypical characteristics typical of astrocytic and oligodendroglial tumors were analyzed by means of Discriminant Analysis, a statistical multivariate analysis, performed on a series of 65 astrocytic and oligodendroglial tumors. This series consisted of 14 WHO grade II and 19 grade III astrocytomas and 24 WHO grade II and 8 grade III oligodendrogliomas. This multivariate analysis enabled an accurate model to be produced that distinguished between astrocytomas and oligodendrogliomas on the basis of 5 cytometry-generated variables. This model was used to characterize the phenotype of each of the 164 glioblastomas. The results show that of these 164 glioblastomas, 6 (about 3.5%) displayed phenotypes that were very similar to oligodendrogliomas, and 141 displayed phenotypes that were very similar to astrocytomas. The phenotypes of the 17 remaining GBMs were too ambiguous to be categorized as having a pure astrocytic or oligodendroglial lineage.

Autoradiographic mapping of 5-HT1B- and 5-HT1D receptors in human brain using [3H]alniditan, a new radioligand

[3H]alniditan, a new potent non-indole serotonin 5-HT1B/1D agonist, was used as a radioligand to characterize 5-HT1B and 5-HT1D receptor (previously termed 5-HT1D beta and 5-HT1D alpha) in various regions of the human brain. Quantitative receptor autoradiography was applied for high anatomical resolution and sensitivity. Highest densities of 5-HT1B/1D receptors were found in the substantia nigra and in the globus pallidus. High to moderate densities were measured in the caudate nucleus, putamen, nucleus accumbens, central gray and hippocampal formation. Very low densities were detected in various cortical regions. In the cerebellum no [3H]alniditan binding was detected. Selective 5-HT1B receptor labeling was achieved using [3H]alniditan in the presence of 300 nM of ketanserin (sufficient to block 5-HT1D receptor labeling). The identity of the 5-HT1B binding sites under these conditions was corroborated by the pIC50 of sumatriptan, which corresponded to its affinity for cloned human 5-HT1B receptors expressed in cells. Surprisingly, the distribution of selective 5-HT1B receptor labeling was completely identical to the distribution of labeling of 5-HT1B + 5-HT1D receptors. The present data indicate that [3H]alniditan is a suitable radioligand for measuring 5-HT1B/1D receptor in the human brain and that the 5-HT1B binding sites are predominant in the presently investigated regions of the human brain.

Differential diagnosis in dementia

Dementia is characterised by progressive memory loss, associated with agnosia, aphasia, dyscalculia, apraxia, and deficits in executive functioning. Alzheimer disease is the most frequent cause of dementia, with vascular dementia, diffuse Lewy body disease, and other etiologies being important differential diagnoses. A strategy and diagnostic hierarchy for diagnosis in dementia is proposed. Diagnostic criteria for Alzheimer disease, diffuse Lewy body disease, and vascular dementia are discussed.

Perfusion and thallium single photon emission computed tomography in herpes simplex encephalitis

This is the first report on 201thallium-single photon emission computed tomography (201Tl-SPECT) brain scan of a patient with herpes simplex encephalitis (HSE). The presented 201Tl-SPECT observations are correlated with 99mtechnetium hexamethylpropylene amine oxime (99mTc-HMPAO) perfusion SPECT and magnetic resonance imaging (MRI) findings. Brain 99mTc-HMPAO perfusion SPECT reveals a hyperperfusion in the right temporal lobe with extension to the parietal lobe and a hypoperfusion in the ipsilateral occipital lobe. 201Tl-SPECT shows a fixation in the right temporal lobe coinciding with the gadolinium enhancement on MRI. The right occipital lesion shown by gadolinium captation on MRI and hypoperfusion on 99mTc-HMPAO perfusion SPECT was not evident on the 201Tl SPECT. These findings could illustrate that the lesions might be different pathophysiologically.

Drug-induced spongiform leucoencephalopathy, a case report with review of the literature

A nineteen year-old girl developed rhabdomyolysis and central pyrexia after the ingestion of multiple drugs: amphetamines, benzodiazepines, methadone, ethanol, and cocaine. On admission, the patient was deeply comatose and during the hospitalisation asymmetrical spastic quadriparesis was noted. Brain biopsy was diagnostic of spongiform leucoencephalopathy. A review of the literature concerning drug-induced spongiform encephalopathy revealed a large amount of heroin-induced cases. The role of cocaine, however, is less well described. After prolonged hospitalisation, our patient improved clinically and radiologically and could be transferred to a rehabilitation center.

Immunoreactivity of presenilin-1 and tau in Alzheimer's disease brain

Mutations in the presenilin-1 gene (PS-1) on chromosome 14 are causative for early-onset familial Alzheimer's disease (AD). In order to study the localization of PS-1 in human brain, a polyclonal antibody, SB63, against a N-terminal epitope of PS-1 (25VRSQNDNRERQEHND40), was raised in rabbits and characterized. Immunolabeling with SB63 of formalin-fixed sections of hippocampus from cases of PS-1-linked AD (PS-1 I143T (AD/A), G384A (AD/B)), sporadic AD, and controls showed a predominant neuronal staining pattern with a stronger immunoreactivity in pyramidal neurons. Staining was mainly granular and localized in the neuronal cell body as well as in neuronal processes. In AD some dystrophic neurites surrounding the amyloid plaques were stained, but no immunoreactivity was observed in the amyloid core. Although PS-1 was present in tangle bearing neurons, colocalization of PS-1 and tau could not be detected using immunofluorescence double labeling. Our data indicate that the pattern of PS-1 immunoreactivity in the hippocampus does not substantially differ between PS-1-linked AD, sporadic AD, and controls.

MR of the brain in Sjögren-Larsson syndrome

Cerebral MR was performed in three patients with Sjögren-Larsson syndrome. In each case, a 1.5-T system was used, and the patient was under general anesthesia. The MR findings included confluent hyperintense white matter lesions in the periventricular and deep white matter of the centrum semiovale, with sparing of the subcortical U fibers. The topography of the white matter abnormalities correlated well with the clinical signs and symptoms.