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Biomedical subjects

K Blennow

Publications and source records attributed to K Blennow.

At least 181 records · Page 10Linked to original sources
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Calpain and calpastatin in normal and Alzheimer-degenerated human brain tissue.

The Ca2(+)-dependent neutral proteases calpain I and II as well as their specific inhibitor, calpastatin, were isolated from normal and Alzheimer-degenerated frozen human brain tissue. In the Alzheimer group calpain I activity was higher in cortex than in mesencephalon. The calpastatin activity was lower in cortex in both groups. This may implicate a higher Ca2(+)-dependent proteolysis in cortex compared to mesencephalon. In the Alzheimer group the cortical calpain II level decreased with an increasing degree of neuropathological changes. In the control group, the level of calpastatin decreased as the number of plaques and tangles increased. Evidence was obtained for a correlation of net calpain activity and the extent of neuropathological changes in cortex.

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Significance of decreased lumbar CSF levels of HVA and 5-HIAA in Alzheimer's disease.

The monoamine metabolites homovanillic acid (HVA), 5-hydroxy-indoleacetic acid (5-HIAA) and 4-hydroxy-3-methoxy-phenylglycol (HMPG) were determined in lumbar cerebrospinal fluid (CSF) of 123 patients with Alzheimer's disease (AD) and 57 healthy controls. Despite CSF sampling under strictly standardized conditions, a wide variability in values among both patients and controls was found, as well as fluctuations in repeated samples from individual patients. This suggests that several unknown factors influence the lumbar CSF levels of monoamine metabolites. The AD group showed significantly lower mean levels of HVA (p less than 0.0001) and 5-HIAA (p less than 0.0001) than the control group. A relation between severity of disease and HVA was also found. The widespread neurotransmitter disturbance in AD, together with the nonspecificity of reduced lumbar HVA and 5-HIAA levels, suggests that the changes are nonspecific, secondary to the cerebral degeneration in AD.

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Increased proteolytic activity in lymphocytes from patients with early onset Alzheimer's disease.

The levels of calpains (m-calpain and mu-calpain) in peripheral blood lymphocytes from patients with Alzheimer's disease were determined via Western blotting. The Ca-dependent proteolytic activity and the calpastatin activity were estimated using incubation with exogenous substrate. Evidence was obtained for an increased Ca-dependent proteolytic activity in lymphocytes from patients with early onset Alzheimer's disease. There was also an increased level of membrane-bound mu-calpain in this group of patients. The observed changes may be caused by a general dysregulation of Ca homeostasis in peripheral cells of early onset Alzheimer victims.

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Decreased monoamine metabolites in frontotemporal dementia and Alzheimer's disease.

The concentrations of the monoamine metabolites homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylglycol (HMPG) in the cerebrospinal fluid (CSF) of patients with clinical frontotemporal dementia (FTD; n = 30), early onset Alzheimer's disease (EAD; n = 33), late onset Alzheimer's disease (LAD, n = 27) and normal controls (n = 31) were determined using HPLC. ANCOVA showed no significant effect of neuroleptic medication, extrapyramidal signs, myoclonia or gender on the CSF levels of the monoamine metabolites. Homovanillic acid was significantly reduced in all diagnostic groups (FTD, p = 0.0002; EAD, p = 0.016; LAD, p = 0.013). 5-Hydroxyindoleacetic acid was significantly reduced in EAD (p = 0.013) and in LAD (p = 0.0014), and HMPG was reduced in LAD only (p = 0.020). HMPG was significantly higher in FTD compared to EAD (p = 0.0005) and LAD (p = 0.0003). CSF-5-HIAA was significantly reduced in patients with antidepressant medication (p = 0.006). ANCOVA within the FTD group showed no significant effect of neuroleptic or antidepressant medication, extrapyramidal signs, myoclonia, gender or FTD subtype on the CSF levels of the monoamine metabolites. The results suggest that CSF-HMPG might differentiate FTD from EAD and LAD, but not from normals.

Adult↗
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Alcoholics with the dopamine receptor DRD2 A1 allele have lower platelet monoamine oxidase-B activity than those with the A2 allele: a preliminary study.

Low platelet monoamine oxidase B (MAO-B) activity and the presence of the Taq1 A1 allele of the dopamine D2 receptor (DRD2) gene have independently been proposed as 'biological/genetic' markers for alcoholism. In the present study, the relationship between these two markers was investigated in a group of socially stable Caucasian middle-aged men with a mean (+/-SD) daily ethanol consumption of 85 +/- 57 g. The platelet MAO-B activity was significantly lower in individuals with the DRD2 A1 allele (n = 8), compared to those without it (n = 29). This relationship remained unchanged when including only subjects who fulfilled DSM-IV criteria for alcohol dependence (n = 27). The finding suggests that alcoholics who are carriers of the DRD2 A1 allele may have lower platelet MAO-B activity.

Adult↗
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The role of the polymorphic genes apolipoprotein E and methylene- tetrahydrofolate reductase in the development of dementia of the Alzheimer type.

The gene for apolipoprotein E (APOE) is polymorphic, and its variant APOE4 is a major risk factor for the development of Alzheimer-type dementia (AD). Another risk factor for AD appears to be negative cobalamin balance, which is very common in elderly people. Cobalamin and folate are interdependent and essential components of the one-carbon metabolism. Another important component is methylenetetrahydrofolate reductase (MTHFR), the gene for which is also polymorphic. Thermolabile MTHFR (tMTHFR), a gene variant that reduces the activity of its enzyme, is common in the general population. In the present study, 75% of 140 AD patients had at least one APOE4 allele. The numbers of APOE4 and tMTHFR alleles correlated significantly with the serum folate levels, however, in opposite directions. The significance of this was augmented by an inverse correlation between APOE4 and tMTHFR. Thus, not only MTHFR but also APOE appears to be related to the one-carbon metabolism, suggesting that APOE4 and insufficient one-carbon metabolism may be synergistic risk factors for AD.

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A quantitative and immunohistochemical study on apolipoprotein E in brain tissue in Alzheimer's disease.

Apoliprotein E (ApoE) has been implicated in the pathogenesis of Alzheimer's disease (AD). Antibodies to ApoE label senile plaques (SP), and an interaction between ApoE and beta-amyloid has been found in in vitro studies. Further, an increased frequency of the ApoE epsilon4 allele in AD has been reported in numerous papers. However, the pathogenetic mechanism of ApoE in AD is not known. We studied ApoE in brain tissue (hippocampus, cerebellum, frontal and temporal cortex) from patients with AD and age-matched control subjects, using both quantitative Western blotting and immunohistochemistry. In AD, a reduction of ApoE was found in the hippocampus (50% of the control value) and in the frontal cortex (52% of the control value), while no significant changes in ApoE levels were found in the temporal cortex or in the cerebellum. Also by immunohistochemistry, ApoE staining was generally decreased in AD brains, both in the neuropil and in the neuronal cellular compartments. Within the AD group, there was no significant correlation between the ApoE level and SP or neurofibrillary tangle (NFT) counts, either in the hippocampus (r = -0.14 and r = 0.55, respectively), or in the frontal cortex (r = -0.03 and r = 0.01, respectively). There were no significant differences in duration, severity of dementia, SP or NFT counts, or ApoE levels between AD patients with different numbers of ApoE epsilon4 alleles. After experimental brain damage in animals, marked increases in ApoE are found, probably as part of lipid recycling in neuronal and synaptic remodelling and regeneration. One may speculate whether the decrease in ApoE may suggest a disturbance in the ApoE system in AD that is unrelated to ApoE isoforms, beta-amyloid deposition and NFT formation. Copyrightz1999S.KargerAG,Basel

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Intrathecal release of nitric oxide in Alzheimer's disease and vascular dementia.

A growing body of evidence points out the potential role of inflammatory mechanisms in the pathophysiology of brain damage in dementia. We have recently demonstrated that patients with Alzheimer's disease (AD) and vascular dementia (VaD) display an intrathecal production of proinflammatory cytokines. TNF-alpha, one of these cytokines, leads to the production of nitric oxide (NO), a potent inflammatory mediator, by induction of inducible NO synthase. The aim of the present study was to investigate the intrathecal levels of nitrate, one of the main metabolites of NO, and to relate its levels to the degree of intellectual impairment, in patients with AD and VaD. Twenty patients with early AD and 26 patients with VaD were analyzed with respect to cerebrospinal fluid levels of nitrate by gas chromatography/mass spectrometry. Interestingly, in patients with AD but not VaD, the intrathecal levels of nitrate were significantly and inversely correlated (r = -0.68, p = 0.002) to the degree of intellectual impairment. Our study demonstrates an inverse correlation between the intrathecal levels of nitrate and the degree of cognitive impairment in patients with AD, suggesting a neuroprotective effect of NO in AD.

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Reduced expression of amyloid precursor protein, presenilin-1 and rab3a in cortical brain regions in Alzheimer's disease.

To study the role of amyloid precursor protein (APP) in the pathogenesis of Alzheimer's disease (AD), the level of APP was analysed by quantitative immunoblotting in 6 AD patients and 6 age-matched controls in 9 brain regions. These were associative cortices (orbital frontal cortex, inferior temporal cortex, inferior parietal cortex), primary cortex (occipital cortex), limbic structures (anterior cingulate gyrus, hippocampus), subcortical structures (putamen, thalamus) and cerebellum. To assess a potential relationship between APP and presenilin-1 (PS-1) and/or synaptic proteins, the levels of PS-1 and rab3a, a specific synaptic vesicle protein, were also determined in the same tissue samples. The level of APP was almost the same in the association cortical regions, primary cortex, and limbic structures and in the subcortical structures, while the lowest level was found in the cerebellum. There were more marked differences in the level of PS-1 and rab3a between different brain regions. The highest levels of PS-1 and rab3a were found in the association cortical areas, while intermediate levels were found in primary cortex, limbic structures and subcortical structures. As for APP, the lowest level was found in cerebellum. We found significantly reduced levels of all three proteins in the association cortices and in hippocampus in AD. Our data show that the protein levels are reduced in specific areas, restricted to neuronal populations that are known to degenerate in AD. Due to the similarity of the expression of APP, PS-1 and rab3a, it is tempting to speculate whether there is a functional relationship between these proteins.

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The cerebrospinal fluid levels of tau, growth-associated protein-43 and soluble amyloid precursor protein correlate in Alzheimer's disease, reflecting a common pathophysiological process.

Cerebrospinal fluid (CSF) levels of tau (total tau), growth-associated protein-43 (GAP-43), soluble amyloid precursor protein (sAPP; i.e. total sAPP), and beta-amyloid(42) (Abeta(42)) were studied in patients with frontotemporal dementia (FTD; n = 14), Alzheimer's disease (AD; n = 47) and vascular dementia (VAD; n = 16), and in age-matched controls (n = 12). CSF-tau was increased in AD compared to controls and FTD (p < 0.001 for both). CSF-GAP-43 was increased in AD compared to controls (p < 0.05), and both CSF-GAP-43 and CSF-sAPP were increased in AD compared to FTD (p < 0.01). Positive and highly significant correlations were found between CSF-tau and CSF-GAP-43 in all groups and between CSF-tau, CSF-GAP-43 and CSF-sAPP in AD. The correlations found may reflect a common pathophysiologic process such as axonal degeneration.

Aged↗
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Decreased levels of intrathecal interleukin 1 receptor antagonist in Alzheimer's disease.

A growing body of evidence points out the potential role of inflammatory mechanisms in the pathophysiology of brain damage in dementia. In previous studies, we have demonstrated intrathecal production of the proinflammatory cytokine tumor necrosis factor (TNF)alpha in patients with Alzheimer's disease (AD). The aim of the present study was to investigate the downstream products of TNF-alpha expression including interleukin (IL)1beta and its naturally occurring antagonist IL-1 receptor agonist (ra) in patients with AD. The cytokine levels were related to neuronal damage, as measured by intrathecal tau and beta-amyloid concentration and certain clinical features of the disease. Fifty-two patients with AD and 25 healthy controls were analyzed with respect to cerebrospinal fluid (CSF) levels of IL-1beta and IL-1ra. CSF IL-1beta was neither detectable in CSF of AD nor in control CSF. In contrast, a significantly lower (p < 0.01) number of patients (24 of 49) than of controls (20 of 24) showed detectable levels of IL-1ra in the CSF. The intrathecal levels of IL-1ra were significantly lower in patients with AD than in the controls. Our study demonstrates a decreased production of the anti-inflammatory compound IL-1ra, suggesting a propensity towards inflammation in patients with AD.

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Treatment of Alzheimer's disease with clioquinol.

As heavy metal ions may be implicated in the formation of senile plaques in Alzheimer-afflicted brains, treatment with clioquinol was tested in 20 patients with Alzheimer's disease. Clioquinol is a chelator that crosses the blood-brain barrier and has greater affinity for zinc and copper ions than for calcium and magnesium ions. Treatment was given for 21 days at doses of 20 mg/day to 10 patients and 80 mg/day to another 10 patients. The study was blind to the dosages but included no controls. Cerebrospinal fluid (CSF) investigations revealed a significant increase at day 7 and a decrease at day 21 in Tau protein and growth-associated protein (GAP43). These proteins are increased in Alzheimer's disease and considered as rather stable markers. The initial increase may indicate a temporary cytotoxicity to the brain and/or an increased release into the CSF from stores in the tissue, possibly from senile plaques where the proteins are accumulated. The levels of CSF-Tau protein correlated positively and significantly with the serum levels of copper and also with the serum copper/zinc ratio. Clinical ratings showed slight improvement after 3 weeks treatment with clioquinol in this open study.

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Intracerebroventricular administration of GM1 ganglioside to presenile Alzheimer patients.

We have conducted a preliminary study of the optimum conditions for a therapeutic effect of ganglioside GM1 in Alzheimer's disease. Five patients with the early onset form of Alzheimer's disease (AD type I) received the ganglioside by intracerebroventricular administration for 12 months. Bilateral stereotactic punction of the frontal horns of the ventricular system was performed, and shunt catheters were implanted and connected to a programmable pump. The optimum GM1 dose varied between 20 and 30 mg/24 h. Neurological neuropsychological, psychiatric and neurochemical examinations were performed 7 days before surgery and on days 30, 90, 180 and 360. No patient found the surgery difficult and no patient or relative regretted that they participated in the study. The patients became more active and safer in relation to others and to performance of various activities from day 90. The cerebrospinal fluid level of the monoamine metabolites homovanillic acid and 5-hydroxyindoleacetic acid and the neuropeptide somatostatin increased.

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Gangliosides and sulfatide in cerebrospinal fluid in leukoaraiosis.

The aim of the study was to evaluate gangliosides and sulfatide in cerebrospinal fluid (CSF) as markers for neuronal degeneration, gliosis, and demyelination in leukoaraiosis (LA). Lumbar CSF samples were taken from 37 elderly subjects with LA on computed tomography (CT). Patients with other pathology than LA or infarction on CT were excluded. In addition, CSF samples were collected from 16 elderly reference subjects without any neurological disease. Gangliosides GM1, GD1a, GD1b, GT1b, GD3, and sulfatide were determined. This concentration of the individual gangliosides and sulfatide showed no correlation with age. Gangliosides GD1b, GT1b, and GD3 were elevated in patients with mild LA compared to controls and patients with moderate or severe LA. GD1a was elevated in patients with mild LA compared to those with moderate LA. The concentration of sulfatide did not differ between the groups. When the patients were grouped in accordance to whether they had had cerebral infarction or not, differences between the groups were not found in the concentrations of any gangliosides and sulfatide. In conclusion, the analysis of CSF markers suggests that neuronal degeneration and gliosis predominate in the early stage of LA.

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The neurochemistry of vascular dementia.

Vascular dementia (VAD) is cognitive impairment caused by changes in the blood circulation of the brain. It is not synonymous with multi-infarct dementia. The latter is a subgroup of VAD. Neurochemical investigations of noninfarcted brain tissue from patients with VAD show general changes in VAD brains. The serotonin metabolism is severely reduced and so is the activity of choline acetyltransferase. Monamine oxidase B is significantly increased in the white matter. A severe decrease in myelin components indicates white matter disturbances of such a degree that they must be considered to be of pathogenetic importance. The levels of some neuropeptides in the hypothalamus are increased. This is a finding which is in agreement with clinical findings of a high activity in the hypothalamic-pituitary-adrenal axis in patients with VAD. This high activity is possibly due to a loss of serotonergic inhibitory tone on the hypothalamus in VAD brains.

Brain↗
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The clinical diagnosis of vascular dementia.

The question was addressed whether the three vascular dementia (VAD) subtypes, multi-infarct dementia (MID), strategic-infarct dementia (SID), and subcortical white matter dementia (SWMD) fulfil the basic criteria for a disease: does a distinct pattern of clinical features match a distinct pathological picture for the various VAD subtypes? No obvious correspondence between structural pathological changes and symptoms or signs was found in the MID and SID subtypes. Therefore, the disease status of these VAD subtypes can be questioned. The VAD subtype SWMD, however, appeared to fulfil the basic criteria for a disease, as the subcortical white matter changes corresponded to the subcortical symptom pattern, with mental slowness, extrapyramidal and bilateral pyramidal deficits.

Brain↗
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Relationship between mental impairment and HPA axis activity in dementia disorders.

In 40 patients with Alzheimer's disease (AD, < 65 years), 56 patients with senile dementia of the Alzheimer type (SDAT, > or = 65 years) and 45 patients with vascular dementia (VAD), basal cortisol levels were estimated and the dexamethasone test (DST) was performed. The degree of dementia was assessed according to DSM-III-R and the GBS scale was used for quantitative measures of functional impairment. There were no significant differences in basal cortisol levels. Especially in the VAD group, scores on functional impairment correlated significantly with post-DST cortisol levels. The results indicate hypothalamic overactivity in demented patients which can be correlated to the degree of dementia. In VAD, and to a certain extent also in SDAT, there appears to be a disconnection between cortical areas, including the hippocampus and the hypothalamus.

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