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P Cras

Publications and source records attributed to P Cras.

At least 37 records · Page 2Linked to original sources
PubMed2001

Endocytic disturbances distinguish among subtypes of Alzheimer's disease and related disorders.

The endocytic pathway is important in amyloid precursor protein (APP) processing and beta-amyloid formation. Our studies have shown that endocytic pathway activation is a prominent and early feature of neurons in vulnerable regions of the brain in sporadic Alzheimer's disease. We report that endocytic pathway abnormalities are present not only in neurons, but in cerebral endothelia in Alzheimer's disease caused by certain APP mutations. The presence or absence of endocytic abnormalities distinguish subtypes of familial Alzheimer's disease linked to APP mutations from presenilin mutations, supporting the notion that different cellular pathways are involved in the altered processing of APP leading to increased beta-amyloid generation in certain of these different Alzheimer's disease subtypes.

Alzheimer Disease↗
PubMed2000

Mapping of serotonin 5-HT(4) receptor mRNA and ligand binding sites in the post-mortem human brain.

The anatomical localization of 5-HT(4) receptor mRNA and 5-HT(4) receptor protein was examined in sections of post-mortem human brain by in situ hybridization histochemistry and radioligand receptor autoradiography. In the in situ hybridization study, the highest levels of 5-HT(4) receptor mRNA were found in caudate nucleus, putamen, nucleus accumbens, and in the hippocampal formation. No 5-HT(4) receptor mRNA was detected in globus pallidus and substantia nigra. For receptor autoradiography, two new and highly selective radioligands were compared: [(3)H]prucalopride, which preferentially labels the G-protein coupled fraction of receptors, and [(3)H]R116712, which labels the entire receptor population at subnanomolar concentrations. [(3)H]Prucalopride and [(3)H]R116712 binding was performed on human brain hemisphere sections. The highest densities for both radioligands were found in the basal ganglia (caudate nucleus, putamen, nucleus accumbens, globus pallidus, substantia nigra). Moderate to low densities were detected in the hippocampal formation and in the cortical mantle. Mismatches between 5-HT(4) receptor mRNA and binding sites in the globus pallidus and the substantia nigra suggested that the binding sites may be localized on axonal projections originating from the striatum. To compare densities of binding sites, concentration binding curves with [(3)H]prucalopride, [(3)H]R116712 and [(3)H]GR113808 were performed on membranes from homogenates of several human brain regions. Comparison of B(max)-values obtained with [(3)H]prucalopride and [(3)H]R116712 indicated that the G-protein coupled fraction of 5-HT(4) receptors in the substantia nigra was exceptionally high (54%) in comparison with percentages (16-27%) found in the frontal cortex, the striatum and the hippocampus. Such a high percentage (40%) of [(3)H]prucalopride vs. [(3)H]R116712 binding was also observed in the substantia nigra in the receptor autoradiography experiments. The [(3)H]prucalopride binding was GppNHp-sensitive, whereas [(3)H]R116712 and [(3)H]GR113808 was not. These data indicate that in the substantia nigra 5-HT(4) receptors are more strongly coupled to their signal transduction pathway than in other brain regions.

Aged↗
PubMed2000

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.

Aggression↗
PubMed2000

Retrospective study of Creutzfeldt-Jakob disease in Belgium: neuropathological findings.

Creutzfeldt-Jakob disease (CJD) is a spongiform encephalopathy that affects about 1 in 10(6) inhabitants in most countries. Recently, a new variant of CJD has been linked to the epidemic of bovine spongiform encephalopathy. Therefore, vigilance concerning the disease's incidence has been increased. We conducted a comprehensive, nation-wide and retrospective study. In 79 Belgian autopsies, we found the characteristic triad of spongiosis, neuronal loss and reactive gliosis. The occipital cortex was most affected, while the cerebellum was mostly spared. Immunohistochemistry was performed using hydrated autoclave pretreatment and several monoclonal antibodies directed against the prion protein. We identified prion-immunoreactive patterns and locations reflecting the important heterogeneity, independently of the antibody that was used. Granular prion immunoreactivity was observed in astrocytes. We studied the regional intensity of the prion immunostaining and determined that the frontal cortex with 95% positive immunoreactivity was best suited for a biopsy. We studied the disease duration in sporadic CJD patients who showed neuropathological lesions of other neurodegenerative disorders (such as Alzheimer's disease). The study shapes the framework in which a prospective neuropathological registry will be able to function.

Amyloid beta-Peptides↗
PubMed2000

Familial Creutzfeldt-Jakob disease in a patient carrying both a presenilin 1 missense substitution and a prion protein gene insertion.

We describe a patient who was clinically diagnosed with familial early-onset Alzheimer disease (AD) carrying both the E318G substitution in presenilin 1 (PSEN1) and an insertion of 7 octapeptide coding repeats in the prion protein gene (PRNP). Neuropathological examination revealed elongated cerebellar prion protein deposits in the absence of AD pathology. Further analysis of other family members showed that the Creutzfeldt-Jakob disease phenotype in this family was caused solely by the PRNP insertion. This observation is consistent with our previous finding that PSEN1 E318G is not causally related to AD.

Adult↗
PubMed1999

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.

Alzheimer Disease↗
PubMed1999

[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.

Creutzfeldt-Jakob Syndrome↗
PubMed1999

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.

Adult↗
PubMed1999

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.

Adult↗
PubMed1999

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.

Adult↗
PubMed1999

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.

Adult↗
PubMed1999

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.

Animals↗
PubMed1999

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)

Brain↗
PubMed1999

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.

Animals↗
PubMed1998

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.

Aged↗
PubMed1998

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.

Alzheimer Disease↗
PubMed1998

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.

Alzheimer Disease↗