Biomedical subjects

J Wegiel

Publications and source records attributed to J Wegiel.

At least 37 records · Page 2Linked to original sources

PubMed1999

Entorhinal cortex of aged subjects with Down's syndrome shows severe neuronal loss caused by neurofibrillary pathology.

In Alzheimer's disease (AD), neurofibrillary degeneration of neurons starts in the transentorhinal cortex and spreads in a time-dependent manner to the entorhinal cortex, which provides a major input to the hippocampus--a key structure of the memory system. People with Down's syndrome (DS) develop neurofibrillary changes more than 30 years earlier than those with sporadic AD. To characterize AD-related pathology in the entorhinal cortex in DS, we examined seven subjects with DS of 60-74 years of age who died in the end stage of AD, and four age-matched control subjects. The volume of the entorhinal cortex in brains of subjects with DS was 42% less than that in control cases; however, the total number of neurons free of neurofibrillary changes was reduced in DS by 90%: from 9,619,000 +/- 914,000 (mean +/- standard deviation) to 932,000 +/- 504,000. The presence of 2,488,000 +/- 544,000 neurofibrillary tangles in the entorhinal cortex of people with DS, the prevalence of end-stage tangles, and the significant negative correlation between the total number of intact neurons and the percentage of neurons with neurofibrillary changes indicate that neurofibrillary degeneration is a major cause of neuronal loss in the entorhinal cortex of people with DS. The relatively low amyloid load (7 +/- 1%) and lack of correlation between the amyloid load and the volumetric or neuronal loss suggest that the contribution of beta-amyloid to neuronal loss in the entorhinal cortex is unsubstantial.

Aged↗

PubMed1998

Neuronal and volume loss in CA1 of the hippocampal formation uniquely predicts duration and severity of Alzheimer disease.

In a series of multiple regression models predicting either duration or severity of Alzheimer disease (AD) patients, significant linear correlations were found consistently for the volume of CA1, the subiculum, and the entorhinal cortex. Similarly, the total number of neurons in CA1, CA4, and the subiculum was correlated significantly with both the duration and the severity of AD. A hierarchical multiple regression model was used to examine whether any of these intercorrelated measures had any unique relationship to disease duration or severity. The results showed that only CA1 demonstrated a unique contribution to the explained variance in predicting duration or severity of AD for volume and for neuronal numbers. These results indicate that in the hippocampal formation, volume and neuronal numbers of CA1 appear to show a unique relationship with clinical measures of AD.

Alzheimer Disease↗

PubMed1998

Reduced number and altered morphology of microglial cells in colony stimulating factor-1-deficient osteopetrotic op/op mice.

The numerical density of microglial cells is reduced by 47% in the corpus callosum, by 37% in the parietal cortex and by 34% in the frontal cortex of mice mutant at the op locus which are totally devoid of colony stimulating factor-1 (CSF-1), the major growth factor for macrophages. Moreover, microglia in the frontal cortex of the op/op mice are smaller and have shorter cytoplasmic processes compared to control mice. Study suggests that CSF-1 plays a role in vivo in the formation and maturation of microglia and has little or no effect on perivascular cells.

Animals↗

PubMed1998

Region- and cell-type-specific pattern of tau phosphorylation in dog brain.

A study of brains of 16 dogs from one to 19 years of age showed a structure- and cell-type- specific pattern of tau protein phosphorylation at mAb Tau-1 site and the absence of phosphorylation at the mAb AT8 site. Strong immunolabeling with mAb Tau-1 of the mossy fibers and perikarya of neurons in sectors CA3 and CA4 of the cornu Ammonis, less intensive staining in the cytoplasm in neocortical and subcortical neurons, and selective staining of some pyramidal cells in sectors CA1 and CA2 show differences in the amount of phosphorylated tau, not only in different types of neurons, but also in different parts of the cell. The immunoreactivity of oligodendrocytes and the absence of the reaction in astrocytes reflect differences in tau phosphorylation in glial cells. Marked immunoreactivity in 13 dogs but minimal reaction in brains of three other dogs appears to reflect interindividual differences, which are associated presumably with genetic background. Shrinkage of neurons, tortuosity of mossy fibers, accumulation of phosphorylated tau in the nucleoplasm, and deformation of the nuclei of neurons and oligodendrocytes suggest that excessive phosphorylation at the mAb Tau-1 site is associated with neuronal and oligodendrocyte degeneration and, possibly, cell death.

Amyloid beta-Peptides↗

PubMed1998

Duration of neurofibrillary changes in the hippocampal pyramidal neurons.

The total number of neurons with and without neurofibrillary changes in sectors CA1 to CA4, subiculum, and dentate gyrus of 16 subjects with Alzheimer disease (AD) was estimated. The duration of neurofibrillary changes was calculated on the basis of regressions between the duration of AD and neuronal numbers. In the CA1 and subiculum, it takes 3.4 and 5.4 years, respectively, for an intact neuron affected by neurofibrillary pathology to become a ghost tangle.

Aged↗

PubMed1998

A novel Polish presenilin-1 mutation (P117L) is associated with familial Alzheimer's disease and leads to death as early as the age of 28 years.

The majority of early-onset familial Alzheimer's disease (FAD) is associated with mutations in the presenilin-1 (PS1) gene. We describe a novel Polish PS1 mutation of Pro117Leu, associated with the earliest average age of onset and death so far reported in a PS-linked, FAD kindred. Human kidney 293 and mouse neuroblastoma N2a cells were stably transfected with wild-type and PS1 P117L. There was a significant increase in the amyloid beta42/40 ratio in the N2a P117L PS1 transfected cells compared with N2a transfected with wild-type PS1. What role PS has in the pathogenesis of AD remains to be determined, however, the severity of the clinical picture associated with this PS1 mutation stresses the importance of presenilin.

Adult↗

PubMed1998

N-methyl-D-aspartate receptor-mediated, calcium-induced calcium release in rat dentate gyrus/CA4 in vivo.

Previously, by using in vivo microdialysis, we demonstrated a huge release of 45Ca2+ from prelabeled tissues to dialysate that was evoked by application of N-methyl-D-aspartate (NMDA) to the rat dentate gyrus (DG) and sector 4 of the cornu ammonis. To establish the mechanism of this phenomenon, in the present study, we characterized its NMDA receptor dependence, investigated the mechanism of 45Ca2+ removal from the cells, and evaluated the possible involvement of calcium-binding protein calbindin D28k and of ryanodine receptors. Microdialysis experiments demonstrated a dose-response relation between NMDA and 45Ca2+ release and sensitivity of this phenomenon to inhibition by 10 microM MK-801 and 5 mM 5-(N,N-dimethyl)-amiloride, thus indicating the NMDA receptor dependence and a role of Na+/Ca2+ exchanger in mediating 45Ca2+ release from cells. Immunocytochemical experiments confirmed that DG granule cells in the investigated inbred rat strain are strongly calbindin D28k-immunopositive, indicating probable involvement of this protein. However, microdialysis studies demonstrated that NMDA-evoked 45Ca2+ release was suppressed by 100 microM dantrolene and 250 microM ryanodine, whereas 50 microM ryanodine stimulated this effect. This points to a key role in the investigated phenomenon of calcium-induced calcium release (CICR) via ryanodine receptors. To our knowledge, this is the first in vivo demonstration of NMDA-evoked CICR. We postulate the usefulness of microdialysis in such studies.

Animals↗

PubMed1998

Binding of amyloid beta-protein to intracellular brain proteins in rat and human.

Amyloid beta-protein (Abeta), in its soluble form, is known to bind several circulatory proteins such as apolipoprotein (apo) E, apo J and transthyretin. However, the binding of Abeta to intracellular proteins has not been studied. We have developed an overlay assay to study Abeta binding to intracellular brain proteins. The supernatants from both rat and human brains were found to contain several proteins that bind to Abeta 1-40 and Abeta 1-42. No major difference was observed in the Abeta binding-proteins from brain supernatants of patients with Alzheimer's disease and normal age-matched controls. Binding studies using shorter amyloid beta-peptides and competitive overlay assays showed that the binding site of Abeta to brain proteins resides between 12-28 amino acid sequence of Abeta. The presence of several intracellular Abeta-binding (AbetaB) proteins suggests that these proteins may either protect Abeta from its fibrillization or alternatively promote Abeta polymerization. Identification of these proteins and their binding affinities for Abeta are needed to assess their potential role in the pathogenesis of Alzheimer's disease.

Alzheimer Disease↗

PubMed1998

Diffuse, lake-like amyloid-beta deposits in the parvopyramidal layer of the presubiculum in Alzheimer disease.

A characteristic feature of the parvopyramidal layer of the presubiculum of 6 individuals with Alzheimer disease (AD) was the presence of large, evenly distributed amyloid-beta (A beta) deposits, which in the end stage of the disease occupy 80.9 +/- 12.2% of the parvopyramidal layer. The strong reaction of A beta deposits with antibodies 4G8 (17-24 amino acids, aa), 6E10 (1-17 aa), and R165 (32-42 aa), and their weak reaction with antibody R162 (32-40 aa) indicate that potentially highly fibrillogenic A beta1-42 is a major constituent of presubicular amyloid. However, A beta deposits in the presubiculum are thioflavin-S- and Congo red-negative--and thus, nonfibrillar--even after 11 to 19 years of AD. The unique properties of presubicular amyloid appear to be related to their origin; amyloid-associated proteins such as apolipoproteins E, and AI, alpha1-antichymotrypsin, and heparan sulfate proteoglycan, which are promoters of fibrillization or stabilizers of A beta in neuritic plaques, are absent; activated astrocytes, which are the source of these proteins, are also absent. The unchanged number and distribution and the resting appearance of microglial cells revealed with RCA-I histochemistry suggest that they do not respond to diffuse A beta deposits. The source of nonfibrillar presubicular A beta is probably local neurons or neuronal projections to the parvocellular layer of the presubiculum. Neuronal, lake-like A beta deposition appears to be characteristic of AD pathology. The presubiculum is most likely the model brain structure for the study of amyloid of exclusively neuronal origin. The parvopyramidal layer of the presubiculum reveals only a small population of the neurons (2.5 +/- 2%) affected by neurofibrillary pathology.

Aged↗

PubMed1998

Cell-type-specific enhancement of amyloid-beta deposition in a novel presenilin-1 mutation (P117L).

The presenilin-1 (PS1) gene mutation (Pro117Leu), recently identified in a Polish family is characterized by the earliest reported onset (from 24-31 years) of Alzheimer disease (AD) and a very short duration of disease (4-6 years). The neuropathology of 2 subjects with this PS1 mutation (ages at death: 35 and 37 years) was compared to four Down syndrome (DS) patients (mean age at death: 62 years) and 4 sporadic AD patients (mean age at death: 79 years with a mean duration of disease of 18 years). The Polish familial AD (FAD) patients showed a marked increase in the amyloid burden of 2 6-fold in most areas of the brain. The entorhinal cortex was an exception where the amyloid burden was similar in each category of patient. Some brain regions of the Polish FAD patients showed a massive increase of amyloid, such as the molecular layer of the cerebellum where a 7- and 25-fold increase was noted, compared with DS and sporadic AD patients respectively. The cerebellar vessel amyloid burden was also greatly increased in the FAD patients, reflecting a vascular compartment specific increase of amyloid beta deposition. The presence of this PS1 mutation has an even greater effect on both vascular and parenchymal amyloid deposition, than the overexpression of the amyloid beta precursor protein present in DS patients, suggesting that PS mutations can be a critical factor determining amyloid deposition.

Adult↗

PubMed1997

Amyloid angiopathy and blood-brain barrier changes in Alzheimer's disease.

Evidence is accumulating that suggests that increased permeability of the BBB to blood-borne proteins is favorable for the development of neuropathologic changes such as amyloid angiopathy and formation of amyloid plaques in the AD brain. To study this problem, we applied a quantitative immunocytochemical procedure that enables evaluation of the barrier function of brain microvasculature to endogenous albumin. This procedure was successfully used on scrapie-infected mice, which represent a unique animal model enabling study of an interrelation between BBB function and deposition of amyloid within vascular wall and neuritic plaques. Biopsy specimens obtained during neurosurgical procedures (tumors and dementia) were also examined. Our observations indicate that (1) the vast majority of brain microvessels in scrapie-infected mice and in demented individuals show normal features of the BBB; (2) only those microvascular segments directly surrounded by amyloid plaques or representing amyloid angiopathy show increased permeability to endogenous albumin; (3) numerous immunosignals over the amyloid deposits in plaques and in the wall of angiopathic vessels suggest the affinity of extravasated albumin to the amyloid material.

Albumins↗

PubMed1997

Immunoreactivity of presenilin-1 in human, rat and mouse brain.

Monoclonal antibodies (mAbs) D3G6 and C8A5, specific for amino acid residues 160-168 of S182 protein, immunolabeled neurons, ependymal and choroid plexus cells, and myocytes in brain sections from normal subjects and people with Alzheimer disease or Down syndrome and in rats and mice. Oligodendroglia, microglia, and the majority of astrocytes were negative. S182 protein or a fragment of the protein detected with these mAbs is not a constituent of amyloid-beta deposits or tangles.

Alzheimer Disease↗

PubMed1997

Metal cations defibrillize the amyloid beta-protein fibrils.

Amyloid beta-protein (A beta) is the major constituent of amyloid fibrils composing beta-amyloid plaques and cerebrovascular amyloid in Alzheimer's disease (AD). We studied the effect of metal cations on preformed fibrils of synthetic A beta by Thioflavin T (ThT) fluorescence spectroscopy and electronmicroscopy (EM) in negative staining. The amount of cross beta-pleated sheet structure of A beta 1-40 fibrils was found to decrease by metal cations in a concentration-dependent manner as measured by ThT fluorescence spectroscopy. The order of defibrillization of A beta 1-40 fibrils by metal cations was: Ca2+ and Zn2+ (IC50 = 100 microM) > Mg3+ (IC50 = 300 microM) > Al3+ (IC50 = 1.1 mM). EM analysis in negative staining showed that A beta 1-40 fibrils in the absence of cations were organized in a fine network with a little or no amorphous material. The addition of Ca2+, Mg2+, and Zn2+ to preformed A beta 1-40 fibrils defibrillized the fibrils or converted them into short rods or to amorphous material. Al3+ was less effective, and reduced the fibril network by about 80% of that in the absence of any metal cation. Studies with A beta 1-42 showed that this peptide forms more dense network of fibrils as compared to A beta 1-40. Both ThT fluorescence spectroscopy and EM showed that similar to A beta 1-40, A beta 1-42 fibrils are also defibrillized in the presence of millimolar concentrations of Ca2+. These studies suggest that metal cations can defibrillize the fibrils of synthetic A beta.

Alzheimer Disease↗

PubMed1997

Media from rhabdomyosarcoma and neuroblastoma cell cultures stimulate in vitro aggregation and fibrillization of amyloid beta-protein.

In vitro aggregation and fibrillization of synthetic amyloid beta-protein Abeta 1-40 was assessed in the conditioned media from rhabdomyosarcoma (CRL 1598, HTB 82, HTB 153, CCL 136), adenocarcinoma (CCL 218), neuroblastoma (SY5Y), and COS cells cultured in the absence and presence of 10% heat-inactivated fetal bovine serum (FBS). The aggregation and formation of cross beta-pleated sheet structures in Abeta was quantitated by Thioflavin T (ThT) fluorescence spectroscopy, while the morphology of Abeta fibrils was examined in negative staining in the electronmicroscope (EM). In cultures supplemented with 10% FBS, the conditioned media from CRL 1598, HTB 82, CCL 218, and SY5Y cell cultures stimulated Abeta aggregation in a time-dependent manner as compared to that of control (serum-containing medium that had not been exposed to cells). The order of stimulation was SY5Y > CRL 1598 > or = HTB 82 > CCL 218, and the stimulation was higher in 2 week cultures than in 1 week cultures. Similar studies using media from HTB 153, CCL 136 and COS cell cultures showed no effect on Abeta 1-40 aggregation. In serum-free cell cultures, only media from SY5Y and CRL 1598 could promote significant aggregation of Abeta 1-40. Negative staining in EM revealed Abeta fibril formation only with conditioned media from SY5Y and CRL 1598 cultured under serum free conditions; no Abeta fibrils were noticed in media from cell cultures supplemented with 10% FBS. We propose that both the SY5Y neuroblastoma cell line and the CRL 1598 rhabdomyosarcoma cell line may serve as experimental models for in vitro studies of extracellular aggregation and fibrillization of Abeta-protein in cell cultures, while rhabdomyosarcoma HTB 82 and adenocarcinoma CCL 218 may be models for study of Abeta aggregation only.

Adenocarcinoma↗

PubMed1997

Relationships between regional neuronal loss and neurofibrillary changes in the hippocampal formation and duration and severity of Alzheimer disease.

The total numbers of neurons with and without neurofibrillary changes in the hippocampal subdivisions were estimated in 16 subjects with Alzheimer disease (AD) and in 5 normal elderly controls. On the basis of clinical symptoms, AD patients were subdivided into relatively less (AD-1. Functional Assessment Staging [FAST] stages 7a to 7c) and more severely affected (AD-2, FAST stages 7e to 7f) patient groups. In the AD-1 group relative to controls, the total number of neurons was reduced only in CA1 and in the subiculum. In the AD-2 group, neuronal losses were found in all sectors of the cornu Ammonis and in the subiculum and ranged from 53% in CA3 to 86% in CA1. The dentate gyrus was the only hippocampal subdivision without significant neuronal loss. Within the combined AD patient groups, significant correlations were noted between both clinical stage and duration of AD and both the total number of neurons and the percentage of neurons with neurofibrillary changes in CA1, CA4, and the subiculum. Regression analyses predicted neuronal losses over the maximal observed duration of 22 years of 87% in CA1, 63% in CA4, and 77% in the subiculum. Our data suggest that over the course of AD, continuous neurofibrillary tangle formation and continuous neuronal loss occur in the hippocampal subdivisions. The rate of neuronal loss appears to be similar for CA1, CA4, and the subiculum.

Aged↗

PubMed1996

Subpopulation of dogs with severe brain parenchymal beta amyloidosis distinguished with cluster analysis.

A study of the brains of 30 dogs, mongrels from 6.5 to 26.5 years of age, revealed that all dogs older than 13 years of age develop amyloid-beta-positive plaques. Cluster analysis based on the age of the dogs and the numerical density of amyloid-positive plaques stained with monoclonal antibody 4G8 (17-24aa) revealed that the population of old dogs consists of two subpopulations: one with a very low (0.8/mm2 on average) and other with a high (19.2/mm2 on average) numerical density of plaques. These two groups (19.5 and 19.1 years of age, respectively) appear to emerge from the younger group (12.2 years of age on average), with moderate (2.2/mm2 on average) numerical density of 4G8-positive plaques. These data may indicate that only a portion of the mongrel population (43%) is susceptible to amyloidosis beta or that only this severely affected subpopulation was exposed to a factor or factors inducing this pathology and developed severe cortical amyloidosis that correlates with age. Dog plaques are only of the diffuse type, with nonfibrillar, thioflavin S-, and Congo red-negative amyloid in all groups distinguished by cluster analysis. Only from 10% of 4G8-positive plaques in the mildly affected group to 29% in the severely and 37% in the moderately affected group are Bielschowsky positive. In the younger, moderately affected group, 6E10 (1-17aa)-positive plaques prevail. In the two old groups with severe and weak changes, almost all 4G8-positive plaques are also 6E10-positive. Carboxy-terminal region immunocytochemistry reveals that BC42-positive plaques are numerous, whereas BC40-positive plaques are few or absent. The differences in the silver-positivity of plaques and their immunoreactivity in both the amino- and carboxy-terminal regions may reflect differences in amyloid-beta deposition and resolution. Dog parenchymal amyloidosis beta appears to be a model for the study of diffuse plaques.

Amyloid beta-Peptides↗

PubMed1996

Promotion of synthetic amyloid beta-peptide fibrillization by cell culture media and cessation of fibrillization by serum.

Dulbecco's modified Eagle's medium promotes aggregation and fibrillization of the synthetic amyloid beta 1-40 and beta 1-42 peptides more than RPMI and OPTI media. Fibrillization in all of these media is faster than in phosphate-buffered saline and Tris buffer. Normal and heat-inactivated fetal bovine and human serum abolish amyloid fibril formation in buffers and cell culture media. Fibrillar amyloid formed during 2-day-long incubation in cell culture media and buffers is defibrillized by 1-day-long treatment with human and bovine serum. This study indicates that amyloid beta fibrillogenesis in cell culture should be studied in serum-free media or in media with a low concentration of serum.

Amyloid beta-Protein Precursor↗

PubMed1996

Overview of methodologic issues for pharmacologic trials in mild, moderate, and severe Alzheimer's disease.

To address the issue of mild, moderate, and severe Alzheimer's disease (AD), it is necessary to initially establish some agreement on terminology. In recent decades, these terms have frequently been defined using screening instrument scores with measures such as the Mini-Mental State Examination (MMSE). There are many problems with this approach, perhaps the most salient of which is that it has contributed to the total and tragic neglect of patients with severe AD. An alternative approach to the classification of AD severity is staging. This approach has advanced to the point where moderately severe and severe AD can be described in detail. Procedures for describing this previously neglected latter portion of AD have recently been extensively validated. Staging is also uniquely useful at the other end of the severity spectrum, in differentiating early aging brain/behavior changes, incipient AD, and mild AD. Temporally, with staging procedures, it is possible to track the course of AD approximately three times more accurately than with the MMSE. The net result of the advances in AD delineation is that issues such as prophylaxis, modification of course, treatment of behavioral disturbances, loss of ambulation, progressive rigidity, and the development of contractures in AD patients can now be addressed in a scientifically meaningful way that will hopefully bestow much benefit in AD patients and those who care for them.

Activities of Daily Living↗