Immunogold study of effects of prenatal exposure to lipopolysaccharide and/or valproic acid on the rat blood-brain barrier vessels

The involvement of blood microvessels, representing the anatomic site of the blood-brain barrier (BBB), in brain damage induced by prenatal exposure to lipopolysaccharide (LPS) and/or valproic acid (VPA) was studied in four-week-old rats. The immunogold procedure was applied for localization at the ultrastructural level of endogenous albumin and glucose transporter (GLUT-1) in three brain regions: cerebral cortex, cerebellum and hippocampus. Four groups of rats were used: (1) untreated control, (2) prenatally VPA-treated, (3) prenatally LPS-treated, and (4) prenatally LPS- and VPA-treated. The functional state of the BBB was evaluated as follows: (a) by its tightness, i.e., permeability to blood-borne albumin, and (b) by the expression of GLUT-1 in the endothelial cells (ECs). Using morphometry, the labelling density for GLUT-1 was recorded over luminal and abluminal plasma membranes of the ECs, also providing information on their functional polarity. No extensive increase of vascular permeability and/or any considerable dysfunction of the BBB in experimental groups nos. 2 and 3 were observed, although in solitary vascular profiles, increased endocytosis or even transcytosis of albumin by ECs was noted. In experimental group no. 4, some vascular profiles showed scanty leakage (microleakage), manifested by the presence of immunosignals for albumin in the perivascular area. Although some fluctuations in the expression of GLUT-1 occurred in all experimental groups, especially in group no. 3, a most pronounced and significant diminution of the labelling density, in all three regions of the brain, was observed in group no. 4. This finding suggests the synergistic action of prenatally applied LPS and VPA that affects specific transport functions of glucose in the microvascular endothelium. The diminished or disturbed supply of glucose to selected brain regions can be one of the factors leading to previously observed behavioral disturbances in similarly treated rats.

Quantitative immunogold study of glucose transporter (GLUT-1) in five brain regions of scrapie-infected mice showing obesity and reduced glucose tolerance

Distribution of glucose transporter (GLUT-1) in the microvascular endothelium of scrapie-infected SJL/J hyperglycemic mice showing clinical signs of scrapie, obesity and reduced glucose tolerance was studied in five brain regions: cerebral cortex, hippocampus, thalamus, cerebellum and olfactory bulb. Uninfected normoglycemic SJL/J mice showing normal glucose tolerance were used as a control. Ultrathin sections of brain samples embedded at low temperature in the hydrophilic resin Lowicryl K4M were exposed to anti-GLUT-1 antiserum followed by gold-labeled secondary antibodies. Labeling density was recorded over luminal and abluminal plasma membranes of microvascular endothelial cells. Ultrastructural observations revealed attenuation of the microvascular endothelial lining in numerous vascular profiles from brain samples of diabetic mice. Morphometric analysis revealed significant decreases of the labeling density for GLUT-1 in the microvasculature of the thalamus, cerebellum and, to a lesser degree, the hippocampus of diabetic mice. No significant differences between diabetic and non-diabetic, control mice were observed in the microvessels supplying cerebral cortex and olfactory bulb. These findings suggest that abnormal glucose metabolism, manifested by reduced glucose tolerance and hyperglycemia, leads to impaired transvascular glucose transport in some brain regions but not in others, presumably disturbing the function of those brain regions supplied by the affected blood microvessels.

Immunogold study of interendothelial junction-associated and glucose transporter proteins during postnatal maturation of the mouse blood-brain barrier

The distribution of glucose transporter (GLUT-1) and of interendothelial junction-associated proteins--zonula occludens protein (ZO-1), occludin, and beta-catenin--was studied using quantitative immunogold procedure. Lowicryl K4M-embedded samples of the cerebral cortex of 1-, 7-, and 14-day-, and 6-week-old (young-adult) mice were used. Ultrathin sections were exposed to specific rabbit polyclonal antibodies followed by colloidal gold-labelled secondary antibodies. We found that the density of immunosignals for GLUT-1 in both luminal and abluminal plasma membranes of the endothelial cells, and those closely related to the interendothelial junctions was low in blood microvessels from newborn mice, dropped slightly at the 7th day, and increased through the 14th day to the level of mature blood-brain barrier (BBB) observed in 6-week-old mice. The expression of ZO-1 was high in newborn mice and increased at the 7th day to the level similar to that found in 14-day- and 6-week-old mice. The expression of occludin was less intense than that of ZO-1 and increased from birth, reaching at the 14th day the level typical for mature BBB found in young-adult animals. The immunosignals for occludin were sparsely distributed inside the junctional clefts. Such a distribution indicates that the tight junctional characteristics are limited to a few short segments of the entire interendothelial cleft. The density of immunosignals for beta-catenin was lowest, and it had the tendency to a gradual, although inconsiderable, drop in the time course of BBB maturation. These findings suggest that the relatively high concentration of GLUT-1 in the interendothelial junctions results from the participation of abluminal plasma membranes of adjacent endothelial cells in the formation of the junctional complexes. The interendothelial junctions of newborn mice are equipped already with the main components of the tight junctions, and the concentration of these components (ZO-1, occludin) reaches the level of the mature BBB at the 14th day of postnatal life.

Fibrillar amyloid-beta affects neurofibrillary changes but only in neurons already involved in neurofibrillary degeneration

The aim of this study of the cerebral cortex of 8 non-demented elderly subjects and of 17 subjects in the severe stage of Alzheimer's disease (AD) (Global Deterioration Scale stage 7/Functional Assessment Staging procedure stage 7a-f) was to examine the relationships between amyloid-beta (Abeta) deposits and neurofibrillary degeneration. The study shows that neuronal processes with neurofibrillary changes are detectable in only a minority of fibrillar plaques: from 31% to 49% of fibrillar plaques within frontal, temporal, parietal, limbic, occipital, and insular cortices. The correlations observed between the numerical densities of neurons with neurofibrillary tangles (NFTs) and the densities of Thioflavin-S-positive fibrillar plaques with neurofibrillary changes (r=0.61; P<0.01) indicate that neurofibrillary pathology in neocortical plaques reflects the topography and rate of neurofibrillary changes in neocortical neurons. The accumulation of abnormally phosphorylated tau in only some plaques indicates that fibrillar Abeta enhances paired helical filament accumulation locally only in dystrophic neurites already involved in neurofibrillary degeneration. The lack of correlation between the number of neurons with neurofibrillary changes and the number of all Thioflavin-S-positive fibrillar plaques (with and without neurofibrillary changes) suggests that beta-amyloidosis does not contribute to initiation of neurofibrillary degeneration in neurons.

Effect of a single embryonic exposure to alcohol on glucose transporter (GLUT-1) distribution in brain vessels of aged mouse

Distribution of glucose transporter (GLUT-1) in brain microvascular endothelium, representing the anatomic site of the blood-brain barrier (BBB), was studied with electron microscopy in 24-month-old mice, which had been exposed prenatally (on 9th day of gestation) to a single teratogenic dose of ethanol. Offspring of mice that had received an equivalent volume of isocaloric dextrose served as controls. Sections of brain samples embedded at low temperature in hydrophilic resin Lowicryl K4M were exposed to anti-GLUT-1 antiserum followed by gold-labelled secondary antibodies. By using morphometry, the labelling density was recorded over luminal and abluminal plasma membranes of the endothelial cells of blood microvessels supplying four brain regions: cortex, hippocampus, cerebellum and olfactory bulb. We found that the density of immunosignals for GLUT-1, represented by colloidal gold particles, was unchanged in the olfactory bulb and slightly lowered in the abluminal plasmalemma of the vascular endothelium in the cerebral cortex of the ethanol-treated mice. In contrast, statistical analysis using Mann-Whitney U-test revealed that in the hippocampus and cerebellum, the density of immunolabelling of both plasma membranes of microvascular endothelial cells was significantly lowered in the ethanol-treated mice. These findings suggest that prenatally applied ethanol had a different influence on the vasculature supplying different brain regions. In effect, the inefficient supply of glucose to selected brain regions can be one of the factors leading to the previously observed deficit in long-term memory in a similar alcohol-treated group of mice.

Microglia cells are the driving force in fibrillar plaque formation, whereas astrocytes are a leading factor in plague degradation

Ultrastructural three-dimensional reconstruction of human classical plaques in different stages of development shows that microglial cells are the major factor driving plaque formation by fibrillar amyloid-beta (Abeta) deposition. The amount of fibrillar Abeta released by microglial cells and the area of direct contact between amyloid and neuron determine the extent of dystrophic changes in neuronal processes and synapses. The volume of hypertrophic astrocytic processes separating fibrillar amyloid from neuron is a measure of the protective activation of astrocytes. On the bases of the volume of amyloid star, microglial cells, dystrophic neurites, and hypertrophic astrocytic processes, and spatial relationships between plaque components, three stages in classical plaque development have been distinguished: early, mature, and late. In early plaque, the leading pathology is fibrillar Abeta deposition by microglial cells with amyloid star formation. The mature plaque is characterized by a balance between amyloid production, neuronal dystrophy, and astrocyte hypertrophy. In late classical plaque, microglial cells retract and expose neuropil on direct contact with amyloid star, enhancing both dystrophic changes in neurons and hypertrophic changes in astrocytes. In late plaques, activation of astrocytes predominates. They degrade amyloid star and peripheral amyloid wisps. The effect of these changes is classical plaque degradation to fibrillar primitive and finally to nonfibrillar, diffuse-like plaques.

Fibrillar amyloid-beta production, accumulation, and recycling in transgenic mice pancreatic acinar cells and macrophages

Amyloid-beta (A beta) production, accumulation, and recycling were examined by light and electron microscopy in the pancreas of transgenic mice (from 45 days to 22 months of age) that express the gene for the carboxy-terminal fragment of the human amyloid-beta protein precursor. Ultrastructural immunocytochemistry revealed four types of cells accumulating fibrillar A beta 1-40 in cytoplasmic vacuoles: acinar pancreatic cells, macrophages infiltrating stroma, epithelial cells of pancreatic ducts, and blood monocytes/macrophages in the lumen of pancreatic vessels. The ultrastructure of amyloid deposits suggests that each of these four types of cells produces fibrillar A beta. Three basic types of amyloid deposits were distinguished: primary vacuoles in different stages of amyloid aggregation and fibrillization, secondary vacuoles that are the product of fusion of primary vacuoles, and phagosome-like vacuoles with morphologically intact fibrillar amyloid and residues of ingested cells. Amyloid production in acinar pancreatic cells starts in mice younger than 45 days, progresses in 2- to 7-month-old mice, and plateaus in the second year of life. In macrophages, amyloid appears in 60-day-old mice, and the increase in the number of macrophages and the amount of amyloid in their cytoplasm correlates with age.

Pattern of neuronal loss in the rat hippocampus following experimental cardiac arrest-induced ischemia

The pattern of neuronal loss in the rat hippocampus following 10-min-long cardiac arrest-induced global ischemia was analyzed using the unbiased, dissector morphometric technique and hierarchical sampling. On the third day after ischemia, the pyramidal layer of sector CA1 demonstrated significant (27%) neuronal loss (P<0.05). At this time, no neuronal loss was observed in other cornu Ammonis sectors or the granular layer of the dentate gyrus. On the 14th postischemic day, further neuronal loss in the sector CA1 pyramidal layer was noticed. At this time, this sector contained 31% fewer pyramidal neurons than on the third day (P<0.05) and 58% fewer than in the control group (P<0.01). On the 14th day, neuronal loss in other hippocampal subdivisions also was observed. The pyramidal layer of sector CA3 contained 36% fewer neurons than in the control group (P<0.05), whereas the granular layer of the dentate gyrus contained 40% fewer (P<0.05). The total number of pyramidal neurons in sector CA2 remained unchanged. After the 14th day, no significant alterations in the total number of neurons were observed in any subdivision of the hippocampus until the 12th month of observation. Unbiased morphometric analysis emphasizes the exceptional susceptibility of sector CA1 pyramidal neurons to hypoxia/ischemia but also demonstrates significant neuronal loss in sector CA3 and the dentate granular layer, previously considered 'relatively resistant'. The different timing of neuronal dropout in sectors CA1 and CA3 and the dentate gyrus may implicate the existence of region-related properties, which determine earlier or later reactions to ischemia. However, the hippocampus has a unique, unidirectional system of intrinsic connections, whereby the majority of dentate granular neuron projections target the sector CA3 pyramidal neurons, which in turn project mostly to sector CA1. As a result, the early neuronal dropout in sector CA1 may result in retrograde transynaptic degeneration of neurons in other areas. The lack of neuronal loss in sector CA2 can be explained by the resistance of this sector to ischemia/hypoxia and the fact that this sector is not included in the major chain of intrahippocampal connections and hence is not affected by retrograde changes.

Neuronal loss and beta-amyloid removal in the amygdala of people with Down syndrome

The decrease in the number of neurons free of neurofibrillary changes, neurons with neurofibrillary degeneration, and the total volume of beta-amyloid (A beta) deposits in the amygdala of people with Down syndrome and in late stages of Alzheimer disease were estimated by using morphometry and regression analysis. This model predicts that the duration of neurofibrillary changes from the pretangle stage to ghost tangles is approximately 4.7 years. The correlation between the decrease in the number of neurons and the decrease in the amount of A beta indicates that amyloid deposition is associated with neurons and that loss of neurons causes decrease in A beta deposition. The presence of neurons only with neurofibrillary tangles, and the absence of the amyloid deposits predicted by regression analysis suggest that neurons with tangles are not engaged in amyloid deposition. The disappearance of amyloid by approximately 2.2 years after loss of neurons free of neurofibrillary changes indicates that A beta deposits are degradable and removable and that even in severely atrophic amygdala, there are mechanisms of amyloid resolution. This study shows that in normal aging in the amygdala, extracellular A beta appears later than neurofibrillary changes.

Cerebellar atrophy in Alzheimer's disease-clinicopathological correlations

Morphometry of the cerebellum of 11 subjects who died in the severe, final stage of Alzheimer's disease (AD) and of five age-matched subjects without dementia revealed significant atrophy in the AD group, with a decrease in the volume of the molecular layer by 24% and of the granular layer by 22% in comparison with controls. The 32% decrease in the total number of Purkinje cells that was observed correlates with the atrophy of the molecular layer, whereas the 30% reduction in the total number of granule cells correlates with the atrophy of the molecular and granular layers. A unique pattern of Alzheimer-type pathology was observed in the cerebellum: (1) there were no neurofibrillary changes in the cerebellum of either the control or the AD subjects, (2) there was almost the same extent of leptomeningeal and cortical amyloid angiopathy in the normal aged subjects and in the AD patients, and (3) the presence of plaques was noted in the AD group, but not in the control group. This pattern of pathology suggests that two factors might be considered in the etiopathogenesis of cerebellar atrophy: (1) transneuronal degeneration and neuronal loss resulting from primary pathologic changes in cerebral structures and (2) parenchymal cerebellar ss-amyloidosis. The correlation between the temporal duration of AD and both the decrease of the total number of granule cells (r=0.86, p<0.01) and the volumetric loss of the molecular (r=0.73, p<0.05) and granular (r=0.93, p<0.001) layers of the cerebellar cortex indicates that these cerebellar atrophic changes are likely to be related to the basic pathologic process of AD. Similarly, the correlation between the most complex parameter the atrophy of the cerebellar cortex and the Functional Assessment Staging (FAST) measure of the clinical severity of AD at the time of demise (r=0.63, p<0.05) as well as with the duration of AD (r=0.78, p<0.01) indicates that cerebellar pathology, when viewed holistically, evolves continuously in association with clinical changes throughout the clinically manifest course of AD.

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.

Relationship of calcium-binding protein containing neurons and projection neurons in the rat basolateral amygdala

Two-laser and two-color approaches were used to observe the colocalization of the calcium-binding proteins, calbindin D28k and parvalbumin, and the retrograde tracer, Fluoro-Gold (FG) in the basolateral amygdala of the rat. The study was performed on five adult rats into which FG was injected to the frontal association cortex. Then, the localization of the retrogradely labeled neurons in the basolateral amygdala was compared with the localization of the neurons labeled by calcium-binding proteins. The present study showed that most of the retrogradely labeled neurons in the posterior part of the basolateral amygdala are also calbindin-positive. Even though a lot of parvalbumin-positive endings were present at the surface of the retrogradely labeled cells, we did not observe the colocalization of the parvalbumin and projective neurons.

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.

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.

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.

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.

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.

Increased blood-brain barrier permeability and endothelial abnormalities induced by vascular endothelial growth factor

The early effects of intracerebrally infused vascular endothelial growth factor (VEGF) on the blood-brain barrier (BBB) to endogenous albumin were studied using a quantitative immunocytochemical procedure. In addition, transmission electron microscopy was used to observe morphological changes induced in brain vasculature. A solution of VEGF in saline (40 ng/10 microliters) was infused into the parieto-occipital cortex of mice, which were killed 10 min, 30 min, and 24 h afterwards. Untreated mice and mice that received infusion of saline only were used as controls. For immunocytochemical evaluation, ultrathin sections of immersion-fixed brain samples embedded in Lowicryl K4M were exposed to anti-albumin antiserum followed by protein A-gold. Simultaneously, other brain samples embedded in Spurr resin were used for ultrastructural examination. Morphometric and statistical analysis indicated that as soon as 10 min after infusion of VEGF, 33% of vascular profiles were leaking albumin, and this value increased at 30 min to 92%. This effect of VEGF appears to be of rather short duration because after 24 h, only 27% of vascular profiles showed signs of leakage. The results of ultrastructural observations indicate that VEGF (30 min post-infusion) induces several changes in microvascular segments located in the area of intracerebral infusion of VEGF. These changes consist of the appearance of interendothelial gaps; fragmentation of the endothelium with formation of segmental, fenestrae-like narrowings; degenerative changes of the vascular basement membrane; and the appearance of fibrin gel in the vessel lumen. At 24 h post-infusion, solitary diaphragmed fenestrae appeared in attenuated segments of the endothelium in a few microvascular profiles. These changes, which are interpreted to be preparatory steps for angiogenesis, affect the structural integrity of the vascular segments, leading to extravasation of blood plasma proteins, including albumin.

Immunocytochemical evaluation of blood-brain barrier to endogenous albumin in scrapie-infected mice

A quantitative immunocytochemical procedure was used for evaluation of the blood-brain barrier (BBB) to endogenous albumin in plaque-forming (PF) and non-plaque-forming (NPF) groups of scrapie-infected mice at the clinical stage of disease. Ultrathin sections of brain samples (cerebral cortex, hippocampus and cerebellum) embedded in resin (Lowicryl K4M) were exposed to anti-mouse albumin antiserum followed by protein A-gold. Using morphometry, the density of immunosignals (gold particles per microns2) was recorded over four compartments: vascular lumen, endothelium, subendothelial space, and brain parenchyma (neuropil). Morphometric and statistical analyses did not reveal significant differences in the barrier function of the microvasculature of the cerebral cortex and hippocampus in either group of mice, although a slight increase in the number of leaking vessels in the PF group was noted. In contrast, in the cerebellum, the permeability of the microvessels to albumin was significantly higher in the PF than in the NPF mouse group, and this was paralleled by the infiltration of the walls of numerous vascular profiles with amyloid deposits (amyloid angiopathy). These data also indicate the existence of distinct regional differences in BBB function in the brain of scrapie-infected mice. The vascular amyloid deposits and the amyloid plaques present in the cerebral cortex of PF mice were labeled with numerous immunosignals suggesting the affinity of extravasated albumin to these deposits. In conclusion, no convincing evidence was obtained indicating that impairment of the BBB, manifested by increased permeability of vascular segments, is directly related to the deposition of amyloid in the vascular wall and in plaques. Segmental impairment of the barrier function seems to be rather the result of disturbed structural integrity of the components of the vascular wall.

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.

Neurofibrillary pathology--correlation with hippocampal formation atrophy in Alzheimer disease

The three-dimensionally reconstructed hippocampal formations in three patients with very severe, immobile Alzheimer disease (AD) and three age-matched nondemented individuals were examined for a correlation between atrophy of hippocampal formation subdivisions and neurofibrillary changes, neuronal loss, and extent of amyloid deposition in plaques and vessels. In AD, a similar severe volume loss was observed in both cellular layers and layers composed of fibers. A strong correlation between the decrease in the volume of hippocampal formation subdivisions and the decrease in the total number of neurons suggests a causative role for neuronal loss in hippocampal formation volumetric loss. Strong regional correlations between the relative decreases in the total number of neurons and the relative increases in the total number of neurofibrillary tangles implicates neurofibrillary pathology as a possible etiologic proximate factor in neuronal and volumetric loss in the hippocampal formation of AD patients.

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.

Differential susceptibility to neurofibrillary pathology among patients with Down syndrome

Individual differences in the development of neurofibrillary changes were examined in eight cortical regions in the brains of 43 subjects with Down syndrome (DS; age range, 15-69 years) using sections stained with monoclonal antibodies (mAb) tau-1 and 3-39. Neurofibrillary pathology was found in 4 cases below 36 years of age and in all 20 cases above that age. In the 24 positive cases, numerical density of pretangles stained with tau-1 and 3-39, respectively, was 6.1/mm2 and 0/mm2; early tangles, 5.0/mm2 and 5.3/mm2; mature tangles, 4.0/mm2 and 5.0/mm2 (p < 0.01); and end-stage tangles, 0.04/mm2 and 2.5/mm2 (p < 0.001). Numerical density of pretangles stained with mAb tau-1 and tangles and plaques stained with mAb 3-39 correlates weakly with age (r = 0.43; p< 0.02), and together with the wide range of numerical densities suggested heterogeneity of the population examined. Cluster analysis based on two variables - i.e., numerical density of pretangles stained with mAb tau-1 and neurofibrillary tangles (NFTs) and plaques stained with mAB 3-39, distinguished three groups of subjects with severe, moderate and weak changes. The severely affected group of 5 subject (21%) had an average 54.6/mm2 of neurons and 13.9/mm/ plaques with neurofibrillary changes, whereas the moderately affected group (6 subjects; 25%) showed a significantly lower numerical density of neurons and plaques with neurofibrillary changes (25.7/mm2 and 8.1/mm2, respectively) as compared with the most affected group. Most of the subjects (13; 54%) belong to the third group with only 2.2/mm2 of neurons and 1.4/mm2 plaques with neurofibrillary pathology. Comparison of these three groups of Down syndrome subjects representing high, moderate, and low susceptibility to neurofibrillary changes with the general population suggests that the risk of Alzheimer disease is similar but the onset of pathological changes is earlier in DS.

New ways of performing in vivo flow velocity measurements in the basilar artery

The basilar artery is the only large artery in which two flows merge, and this is reflected in the flow downstream. We report quantitative flow-velocity measurements with a phase-based MR technique, i.e. the Fourier velocity encoding method, in the basilar artery of a volunteer. To our knowledge, this has not previously been performed successfully. A comparison is made with the results of flow velocity measurements in the basilar artery with transcranial Doppler ultrasonography; the techniques agreed very well. Although Doppler ultrasonography is still most widely used, no information on the flow rate and the flow velocity distribution in the basilar artery can be provided. MR flow measurement techniques appear promising when detailed information on the flow velocity distribution and flow rate is needed.

The origin of amyloid in cerebral vessels of aged dogs

Our morphometric study of 30 dogs, mongrels, from 6.5 to 26.5 years of age, shows amyloid angiopathy in cortical and leptomeningeal vessels of all dogs older than 13.2 years of age, and the increase in the numerical density of amyloid-positive vessels correlated with age. Cluster analysis distinguished the group of six dogs (25%) to be relatively less affected, a large group of 13 animals (54%) to have moderate pathology, and five dogs (21%) to have severe amyloid angiopathy. Amyloid accumulation starts in large vessels, particularly in the tunica media of large arteries. Amyloid deposition appears to be associated with smooth muscle cells. Ultrastructural studies of samples from nine dogs are in agreement with in vitro studies suggesting that smooth muscle cells are the source of soluble amyloid beta. beta-protein polymerizes in the basal lamina of the tunica media. Muscle cells in the area of amyloid-beta accumulation degenerate and die. Thioflavin-positivity of only 24% of cortical and 66% of leptomeningeal beta-protein-positive vessels suggests that thioflavin-negative deposits contain soluble, not yet fibrillized protein and/or partially degraded and depolymerized amyloid.

Atrophy of hippocampal formation subdivisions correlates with stage and duration of Alzheimer disease

The hippocampal formations of 13 subjects with severe Alzheimer disease [AD; Global Deterioration Scale (GDS) stage 7] and of 5 age-matched subjects without symptoms of dementia were reconstructed from serial sections. Functional assessment staging (FAST) was used at the time of demise to assess 9 patients at stages 7a-c (incipient averbal and nonambulatory) and 4 patients at stages 7e-f (immobile). The duration of the disease from FAST stage 5 until demise ranged from 2 to 8 years in the first of these subgroups, and from 10 to 13 years in the second. The volumes of the entire hippocampal formation and of the cornu ammonis, its sectors and layers, the dentate gyrus, the subicular complex, and the entorhinal cortex were calculated. Hippocampal formation volume decreased by 36% in the incipient averbal and nonambulatory patients and by 60% in the severely functionally impaired immobile patients, in comparison with controls. In the final substages of AD, immobile patients exhibited significant atrophy, in comparison with controls, in the cornu ammonis and all of its sectors and layers except CA4, the subicular complex and all of its parts, and the entorhinal cortex (p < 0.05). Within the AD patient group, significant correlations were noted between both the magnitude of functional severity and the duration of AD and the volumes of most hippocampal formation subdivisions studied. For the cornu ammonis, subicular complex, and entorhinal cortex, volumetric loss correlations with FAST stage 7 ordinally enumerated substages were r = -0.71, -0.79, and -0.62, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

[Homicide in affective states and the problem of responsibility]

The penal code dated April 19th 1969 allows for three privileged types of manslaughter: manslaughter under strong emotional disturbance (art. 148 sections 2), infanticide (art. 149) and euthanasia for request (art. 150). The first two types of manslaughter are the discussed the third one is neglected because only the general problems of soundness of mind, non-accountability and greatly diminished accountability (art. 25 penal code) refer to them. In the situation when strong emotional disturbance exists (so called physiologically conditioned emotional disturbance) from art. 148 sections 2 penal code and one of the mentioned states mentioned in art. 25 penal code (mental deficiency, mental disease, other mental disorders) results in greatly diminished accountability and the cumulative qualification from art. 148 sections 2 and art. 25 sections 2 penal code will be admissible. As far as infantcide is concerned, the following opinion has been expressed that physiologically proper childbirth does not cause disconnection or restriction of soundness of mind. But in the case of psychological disorders such possibility cannot be excluded. The author postulates a wide participation of experts in psychology and psychiatry in cases prosecuted under art. 148 sections 2 penal code and art. 149 penal code.

A quantitative immunocytochemical study of the osmotic opening of the blood-brain barrier to endogenous albumin

The time sequence of the blood-brain barrier opening to endogenous albumin in rat brain after intracarotid infusion of hyperosmolar L(+)arabinose was studied using quantitative immunocytochemistry. Brain samples obtained 1, 5, and 30 min after insult were immersion-fixed in formaldehyde-glutaraldehyde mixture and embedded at low temperature in Lowicryl K4M. Untreated rats or rats exposed only to Ringer's solution were used as a control. Ultrathin sections were exposed to anti-rat albumin antiserum followed by protein A-gold. The density of immunosignals (gold particles per square micrometre) was recorded over four compartments: vascular lumen, endothelium, subendothelial (perivascular) space including basement membrane, and brain parenchyma (neuropil). The labelling density of the vessel lumen, containing blood plasma, was considered to represent 100% of the circulating albumin. Morphometric and statistical analysis indicated that in control animals only 0.4-0.6% of circulating albumin appears in the subendothelial space and in the basement membrane. As soon as one minute after L(+)arabinose infusion, this value increased to 3%, followed by a further increase to 25% and 56% after 5 and 30 min, respectively. A slow increase of the labelling density in the adjacent neuropil suggests that the basement membrane represents an obstacle for escaping albumin, which apparently sticks to or is trapped by this membrane. The results indicate that the applied procedure, although based on morphometric analysis of static electron micrographs can also be used for studying dynamic processes such as transvascular passage of albumin after disruption of the brain-blood barrier.

Noninvasive determination of local wavespeed and distensibility of the femoral artery by comb-excited Fourier velocity-encoded magnetic resonance imaging: measurements on athletic and nonathletic human subjects

The local distensibility of arteries is of interest because distensibility varies from artery to artery, may be altered by disease to different extents in different arteries, and may be modified by physiological or pharmacological means. Using magnetic resonance imaging (MRI) we have measured local arterial wavespeed in the femoral artery in healthy human subjects and calculated local arterial distensibility. We acquired 2-D coronal and sagittal MR phase contrast angiograms of the femoral artery. We used a novel imaging technique, comb-excited Fourier velocity-encoded MRI, to obtain simultaneous measurements of arterial blood velocity at two stations 14 cm apart on the femoral artery. The separation of the two stations divided by the delay between the onset of forward flow at the two stations was used to calculate the wavespeed. The measurements were made on 16 healthy men (8 athletes, 8 non-athletes) in the age range 20-30 years, who were scanned with the use of ECG gating and an extremity coil in a 1.5 Tesla scanner (GE Medical Systems, Milwaukee, WI). By systematically altering the delay between the R-wave and data acquisition, a temporal resolution of 2-4 ms was achieved. The onset of forward flow at each station was determined from a least-squares fit to the data for 30% of the maximum velocity during the cardiac cycle. Average femoral artery wavespeed was 7.7 m/s +/- 1.2 in the athletes and 11.5 m/s +/- 1.1 in the non-athletes (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous detection of multiple components of motion with MRI

OBJECTIVE

Simultaneous detection of two or more components of motion using new magnetic resonance pulse sequences was investigated.

MATERIALS AND METHODS

The technique employs Fourier phase encoding to encode the first component, and phase contrast detection to encode the second. Although the technique can be generalized to any number of spatial dimensions and motional orders, applications in which one or two spatial dimensions are obtained with a single Fourier velocity or acceleration dimension are most likely to be useful. For example, Fourier-encoded velocity and phase-contrasted acceleration information can be combined into the same image.

RESULTS

Several variations of the pulse sequence were investigated in phantoms and human volunteers. The first variation acquired images having an appearance similar to that of Fourier velocity-encoded images in which signal displacement is proportional to velocity, but with pixel intensity determined by acceleration. In another variation two spatial dimensions were acquired with a third dimension that uses Fourier velocity encoding to measure axial velocity within a curved tube. Radial velocity components were determined simultaneously with a second velocity-encoding gradient pulse.

CONCLUSION

The phantom and in vivo results presented here suggest that simultaneous detection of two or more components of motion is feasible.

Neurofibrillary pathology in brains of elderly schizophrenics treated with neuroleptics

The clinical histories of 102 schizophrenics who died at 70 years of age or older were reviewed. The incidence of neurofibrillary tangles (NFTs) was two times higher in the patients who received (74%) than in those who did not receive (36%) treatment with neuroleptics. The development of NFTs started earlier in the treated group. Further studies comparing brains of nine schizophrenics (average age, 86 years) who did not receive treatment with neuroleptics and seven age-matched cases who received neuroleptics, both with neurofibrillary pathology and neuritic plaques, showed characteristic differences. The numerical density of NFTs was slightly greater in the cornu Ammonis (CA1 and CA2) and subiculum of treated patients. Significantly lower numerical density and lower percentage of pretangles (stage 0) and early and mature tangles (stages 1 and 2) and increased number of end-stage tangles (stage 3) were found in the CA, subicular complex, and cerebral cortex of the treated group. These changes suggest accelerated neurofibrillary degeneration in neurons. A significant increase in the numerical density of tau-1-positive plaques was observed in sector CA1 of the CA (from 0.15/mm2 to 17.36/mm2), subiculum (from 0/mm2 to 16.62/mm2), temporal cortex (from 0.14/mm2 to 9.46/mm2), and occipital cortex (from 0.08/mm2 to 0.39/mm2). The higher numerical density of tau-1-positive plaques, but not of 4G8-positive plaques, indicates acceleration of neurofibrillary changes in the plaques of patients treated with neuroleptics. The significant decrease (20-25%) in the numerical density of neurons in the pyramidal layer of sectors 2-4 in the CA appears to be associated with accelerated neurofibrillary changes in neurons and plaques in the treated group. This study demonstrates that chronic treatment with neuroleptics--not schizophrenia itself--significantly increases the risk of more frequent, earlier, and accelerated development of neurofibrillary pathology in the brains of elderly schizophrenics.

Dural sinus occlusion due to calvarial metastases: A CT blind spot

Dural sinus thrombosis can be a difficult diagnosis to establish because it may present with nonspecific signs of raised intracranial pressure. Diagnosis by CT is well documented but signs may be subtle. Angiography is the "gold standard" but is invasive and requires a very high index of clinical suspicion to request. Magnetic resonance offers a method of demonstrating the dural sinuses in multiple planes and, furthermore, flow within the sinuses may be depicted by MR angiography. We report on three cases where the diagnosis of superior sagittal sinus thrombosis due to calvarial metastases was missed by CT, primarily due to their site over the convexity, but was demonstrated accurately using MR with MR angiography.

The measurement of time-averaged flow by magnetic resonance imaging using continuous acquisition in the carotid arteries and its comparison with Doppler ultrasound

A continuous acquisition method was used to measure the time-averaged flow in the carotid arteries of 10 normal volunteers, using an interleaved flow-sensitive and flow-compensated field echo sequence on a 1.5 T magnetic resonance (MR) system. Validation of the sequence and technique was performed using a pulsatile rotating phantom. The measured flow rates for the common carotid arteries were compared with Doppler ultrasound values obtained immediately after the MR measurement using a Duplex scanner. The correlation (r = 0.52, P less than 0.01) was significant with data spread accounted for by the inherent errors of both techniques. The difference between time-averaged flow measured by MR and Doppler ultrasound was 1.9%. Short-term reproducibility of each technique was assessed by consecutive measurements with values of 6.8% and 6.6% respectively for MR and Doppler; measurements after a 2 - 4 week interval gave a long-term reproducibility of 11.8% and 9.8% respectively. The advantages of continuous acquisition make the method suitable for non-invasive flow measurements, particularly for vessels that are not accessible to ultrasound.