Search PubMed⌕ Search

Biomedical subjects

K Blennow

Publications and source records attributed to K Blennow.

At least 91 records · Page 5Linked to original sources

Growth-associated protein GAP-43 in the frontal cortex and in the hippocampus in Alzheimer's disease: an immunohistochemical and quantitative study.

We studied the growth-associated protein, GAP-43 (also called neuromodulin and B-50) in post-mortem brain tissue using immunohistochemistry and quantitative Western blotting, from patients with Alzheimer's disease (AD) and age-matched control subjects. By immunohistochemistry, we found a clear reduction of GAP-43 in the frontal cortex, while in the hippocampus, there was a marked reduction in some areas (dentate molecular layer, stratum moleculare and radiale of CA1 and CA4), while not in other areas (stratum lacunosum, pyramidale and oriens of CA1). Moreover, in the hippocampus, neuritic staining was prominent, and was often associated with senile plaques. Quantitative analysis showed that GAP-43 was significantly reduced in AD, both in the frontal cortex (70% of the control value, p < 0.01) and in the hippocampus (81% of the control value, p < 0.05). In the frontal cortex, there was a significant negative correlation between GAP-43 and duration of dementia (r = -0.58; p < 0.02) and a positive correlation between GAP-43 and the synaptic vesicle-specific protein rab3a (r = 0.62; p < 0.05), while no such correlation were found in the hippocampus. In contrast, a significant positive correlation was found between GAP-43 and the number of senile plaques in the hippocampus (r = 0.64; p < 0.05), but not in the frontal cortex. GAP-43 is known to be involved in maintenance of synapses and in neuritic regeneration. Our findings may suggest that in the frontal cortex, GAP-43 levels decline as a consequence of the synaptic degeneration, while in the hippocampus, sprouting processes, involving GAP-43, are active.

Aged↗

Putamen mitochondrial energy metabolism is highly correlated to emotional and intellectual impairment in schizophrenics.

In a recent study, we demonstrated that cytochrome-c oxidase (COX), an indicator of neuronal activity, is increased in several brain regions from chronic, medicated schizophrenics. In the present study, to address the functional significance of those findings, we have measured COX activity in a group of schizophrenics in whom antemortem geriatric measures of motor, intellectual, and emotional impairment had been assessed. COX activity in the putamen was strongly negatively correlated with emotional (r = -.76; p < .005) and intellectual impairment (r = -0.76; p < .005), but not with motor impairment (r = 0.01). No significant correlations could be found in the frontal cortex, thalamus, caudate nucleus, globus pallidus, mesencephalon, or nucleus accumbens. Dopamine D2 receptor density in the putamen, measured with [3H]raclopride, was elevated in schizophrenics as compared to controls, as were Kd values. In contrast to COX activity, D2 receptor binding was moderately, but significantly positively correlated with intellectual impairment (r = 0.64; p < .05) but not with motor impairment. Results expose a unique anomaly in the effects of neuroleptics in terms of increasing neuronal signaling in the putamen, which may underlie a reversal of cognitive deficits in schizophrenics, while at the same time, elevating D2 receptor density that seems to be detrimental.

Aged↗

Measurement of apolipoprotein E (apoE) in cerebrospinal fluid.

Apolipoprotein E (apoE) is a protein involved in transport of lipids and has been implicated to play an important role in regeneration after nerve injury. Determination of apoE in cerebrospinal fluid (CSF) thus have a potential interest when studying different forms of brain damage and as a marker of ongoing regenerative processes in the brain. However, previous studies on CSF-ApoE in Alzheimer's disease (AD) have given inconclusive results. Such inconsistent results might be related to confounding factors interfering with sample handling and/or analyses, which have not been fully elucidated. We therefore examined different potential confounding factors for analyses of apoE in CSF and also developed a new enzyme linked immunosorbent assay (ELISA). The hydrophobic character of ApoE resulted in adsorption to different types of test tubes commonly used for collection of CSF at lumbar puncture, resulting in falsely low levels. This makes CSF handling critical, especially if samples are taken in different types of tubes, or is transferred to new tubes. Taking this confounding factors in consideration and analysing patient and control CSF handled in the same way and using the new ELISA, we could confirm our previous finding of reduced levels of ApoE in AD, (3.4 +/- 1.3 mg/l) compared with controls (4.5 +/- 2.7 mg/l) (p = 0.045). Both in the AD and in the control group, higher levels of CSF-ApoE was found in individuals possessing the ApoE4 alleles. Our results support that CSF-ApoE is reduced in AD, and that handling of CSF is a critical factor, which may explain the discrepant results from previous studies. Differences in the amount of patients and controls possessing the ApoE4 allele included might also increase the variance between different studies.

Aged↗

CSF sulfatide distinguishes between normal pressure hydrocephalus and subcortical arteriosclerotic encephalopathy.

OBJECTIVES: To examine the CSF concentrations of molecules reflecting demyelination, neuronal and axonal degeneration, gliosis, monoaminergic neuronal function, and aminergic and peptidergic neurotransmission in a large series of patients with normal pressure hydrocephalus (NPH) or subcortical arteriosclerotic encephalopathy (SAE), to elucidate pathogenic, diagnostic, and prognostic features. METHODS: CSF concentrations of glycosphingolipid (sulfatide), proteins (neurofilament triplet protein (NFL), glial fibrillary acidic protein (GFAP)), neuropeptides (vasoactive intestinal peptide (VIP), 4-aminobutyric acid (GABA)), and monoamines (homovanillic acid (HVA), 5-hydroxy-indoleacetic acid (5-HIAA), 4-hydroxy-3-methoxyphenylglycol (HMPG)) were analysed in 43 patients with NPH and 19 patients with SAE. The diagnoses of NPH and SAE were based on strict criteria and patients with NPH were subsequently operated on. Twelve clinical variables, psychometric tests measuring perceptual speed, accuracy, learning, and memory and a psychiatric evaluation were performed in all patients and before and after a shunt operation in patients with NPH. RESULTS: The CSF sulfatide concentration was markedly increased in patients with SAE (mean 766, range 300-3800 nmol/l) compared with patients with NPH (mean 206, range 50-400 nmol/l) (p<0.001). 5-HIAA, GABA, and VIP in CSF were higher in patients with SAE than in patients with NPH. The patients with NPH with cerebrovascular aetiology had higher sulfatide concentrations and a poorer outcome after shunt surgery than patients with NPH with other aetiologies. CONCLUSIONS: The pathogenesis of the white matter changes in NPH and SAE is different and ischaemic white matter changes can be a part of the NPH state. The markedly increased CSF sulfatide concentrations in patients with SAE indicate ongoing demyelination as an important pathophysiological feature of SAE. The CSF sulfatide concentration distinguished between patients with SAE and those with NPH with a sensitivity of 74% and a specificity of 94%, making it an important diagnostic marker.

Adult↗

Symptoms, vascular risk factors and blood-brain barrier function in relation to CT white-matter changes in dementia.

The aim was to study the frequently found white-matter changes on computerized tomography (CT) in patients with dementia and to relate these changes to clinical regional brain symptomatology, vascular factors, albumin ratio [indicator of blood-brain barrier (BBB) function] and other CT changes. The study included 85 patients, average age 71 +/- 8, with Alzheimer's disease (n = 56) and vascular dementia (n = 29), who underwent CT (Siemens Somatome DR 1) of the brain. They were inpatients in a psychiatric department specialized in dementia investigations. The degree of CT white-matter changes (absence, mild-moderate, severe) was the basis for the division of the patients into three groups. As the patients without white-matter changes were significantly younger than those with such changes, all statistical analyses were controlled for age. Subcortical symptomatology was significantly more frequent in the group with severe white-matter changes, whereas the reverse was true for parietal symptomatology. Diabetes mellitus, hypertension, ischemic cardiac disease and lacunas were significantly more common in patients with white-matter changes, whereas the frequency of transient ischemic attack/stroke episodes did not differ significantly between the groups. The albumin ratio was significantly higher in the groups with white-matter changes and highest in the group with severe white-matter changes. The findings indicate that white-matter changes in demented patients are at least partially an age- and stroke-independent disease manifestation of the vascular system and is associated with a specific symptom pattern. BBB dysfunction may be the link between the vasculature and the tissue damage.

Aged↗

Standardization of measurement of beta-amyloid(1-42) in cerebrospinal fluid and plasma.

The standardization and clinical validation of the measurement of beta-amyloid(1-42) (Abeta42) in cerebrospinal fluid (CSF), plasma and urine is described using a commercially available sandwich-type ELISA with 21F12 and 3D6 as monoclonal antibodies. The INNOTEST beta-amyloid(1-42) allows the specific and reliable measurement of(1-42) amyloid peptides in CSF and plasma. The Abeta42 concentrations in serum and urine were below the detection limit. In plasma, no differences were found in Abeta42 levels between controls and patients with different neurodegenerative disorders (Alzheimer's disease (AD), Lewy body disease (LBD), others). In contrast, CSF-Abeta42 concentrations were lower in AD and LBD patients as compared to controls. No correlation was found in AD patients between CSF and plasma concentrations of Abeta42 or between CSF Abeta42 levels and blood-brain-barrier function. The quantitative outcome of the test is in part dependent on confounding factors such as tube type, freeze/thaw cycles, temperature of incubation, standard preparation protocol, and antibody selection. Notwithstanding these aspects, it emerged that Abeta42 is a useful biochemical marker for the diagnosis of AD patients, but there is a need for an international Abeta standard, a universally accepted protocol for CSF preparation, and a thorough evaluation of assay performance in function of the boundary conditions.

Alzheimer Disease↗

Cerebrospinal fluid markers for Alzheimer's disease evaluated after acute ischemic stroke.

Potential cerebrospinal fluid (CSF) markers for Alzheimer's disease (AD) include tau protein, the 42 amino-acid form of amyloid beta (amyloid beta(1-42)) and apolipoprotein E (apoE). To study new aspects of these protein markers, we examined consecutive CSF samples from 26 patients with acute ischemic stroke. CSF samples were taken on day 0-1, day 2-3, day 7-9, 3 weeks and 3-5 months after the stroke. CSF-tau showed a marked increase day 2-3, which peaked after 1 week and returned to normal after 3-5 months. CSF-tau also showed correlation (r=0.95; p<0.01) with the size of the infarct. In contrast, CSF-amyloid beta(1-42) and CSF-apoE showed no significant changes during the period. The marked increase in CSF-tau levels after acute ischemic stroke indicate that CSF-tau reflect the degree of neuronal damage. The reason for unchanged levels of CSF-amyloid beta(1-42) and CSF-apoE after ischemic stroke remains unclear.

Journal Article↗

Reduction of the small synaptic vesicle protein synaptophysin but not the large dense core chromogranins in the left thalamus of subjects with schizophrenia.

BACKGROUND: It has been hypothesized that a lesion in the neuronal circuits of thalamus might contribute to the symptoms in schizophrenia. It has also been suggested that impaired synaptic transmission is an important component of the pathophysiology of schizophrenia. In the present study we assess the synaptic integrity of thalamus by means of examining the protein levels of: (1) synaptophysin, a membrane bound protein of small synaptic vesicles, and (2) chromogranins, a family of soluble secretory proteins stored and released from the secretory large dense-core vesicles. METHODS: The brains of 9 patients with schizophrenia and 9 age-matched control subjects were studied. The levels of synaptophysin and chromogranins were measured by radioimmunoassays. RESULTS: The amount of synaptophysin in the left thalamus was significantly decreased (p = .036) in the schizophrenic group (2655 +/- 605 nmol synaptophysin/mg total protein) compared to the control group (3248 +/- 827 nmol synaptophysin/mg total protein). There were no differences between the groups in the levels of chromogranins, nor in the levels of synaptophysin of the right thalamus. CONCLUSIONS: These findings indicate defect synaptic function in the left thalamus of patients with schizophrenia. This may be the cause of a reduction of synaptic terminals or a defect limited to certain structures of the synapse, namely the small presynaptic vesicles.

Aged↗

Increased cerebrospinal fluid protein tau concentration in neuro-AIDS.

OBJECTIVES: Assessment of cerebrospinal fluid (CSF) levels of protein tau in human immunodeficiency virus type 1 (HIV-1) infection. MATERIAL AND METHODS: CSF tau levels were analyzed in 52 HIV-1-infected patients, 37 of whom had no neurological symptoms, eight had aquired immunodeficiency syndrome (AIDS) dementia complex (ADC), and seven had AIDS with other neurological complications. RESULTS: A significantly higher mean CSF tau concentration was found in patients with ADC (380 pg/ml) compared with patients with neuroasymptomatic HIV-1 infection (120 pg/ml, P<0.01) and HIV-negative controls (150 pg/ml, P<0.05). No difference in CSF tau levels was found between patients with ADC and patients with AIDS with other neurological complications. CONCLUSION: CSF tau might be used as a biochemical marker for axonal degeneration and might be of use to identify HIV-1-infected patients with ADC and other neurological complications, but it cannot discriminate between ADC and other neurological complications in HIV-1-infection.

AIDS Dementia Complex↗

The synaptic-vesicle-specific proteins rab3a and synaptophysin are reduced in thalamus and related cortical brain regions in schizophrenic brains.

Two synaptic-vesicle proteins, rab3a and synaptophysin, have been studied on post-mortem brain tissues of schizophrenics and healthy controls. We found significantly reduced levels of rab3a in thalamus (p<0.001); for both proteins in gyrus cinguli and hippocampus (p<0.0001); for rab3a in frontal and parietal cortex (p<0.05); and no differences in temporal cortex or cerebellum in schizophrenics compared with controls. Reduced synaptic density may be a prominent feature of the molecular neuropathology of schizophrenia.

Adult↗

Sensitivity, specificity, and stability of CSF-tau in AD in a community-based patient sample.

OBJECTIVE: To evaluate the sensitivity and specificity of CSF-tau in clinical practice as a diagnostic marker for AD compared with normal aging and depression, to study the stability of CSF-tau in longitudinal samples, and to determine whether CSF-tau levels are influenced by different covariates such as gender, age, duration or severity of disease, or possession of the APOE-epsilon4 allele. METHODS: Consecutive AD patients from a community-based sample were studied, including 407 patients with AD (274 with probable AD and 133 with possible AD), 28 patients with depression, and 65 healthy elderly control subjects. A follow-up lumbar puncture was performed in 192 AD patients after approximately 1 year. CSF-tau was determined using a sandwich ELISA, which was run as a routine clinical neurochemical analysis. RESULTS: CSF-tau was increased in probable (690+/-341 pg/mL; p < 0.0001) and possible (661+/-447 pg/mL; p < 0.0001) AD, but not in depression (231+/-110 pg/mL) compared with control subjects (227+/-101 pg/mL). Receiver operating characteristics analysis showed that a cutoff level of 302 pg/mL resulted in a sensitivity of 93% (95% CI, 90-96%) and a specificity of 86% (95% CI, 75-94%), with an area under the curve of 0.95 to discriminate AD from control subjects. Within the AD group, CSF-tau did not differ significantly between baseline and follow-up investigations, and was relatively stable between baseline and 1-year follow-up levels, with a coefficient of variation of 21.0%. High CSF-tau levels were also found in most AD patients with very short duration of dementia, and with Mini-Mental State Examination scores >23 (n = 205). In total, 193 of 205 patients (sensitivity, 94%) had a CSF-tau level higher than 302 pg/mL. CONCLUSIONS: CSF-tau has a high sensitivity and specificity to differentiate AD from normal aging and depression, as demonstrated in a large community-based series of consecutive AD patients during which analyses were run continually in a clinical neurochemical laboratory. The increase in CSF-tau is found very early in the disease process in AD, is stable over time, and has a low interindividual variation on repeated sampling. Although high CSF-tau is found in some neurologic conditions (e.g., stroke), these findings suggest that CSF-tau may be of use to help in differentiating AD from normal aging and depression, especially early in the course of the disease, when the symptoms are vague and the diagnosis is especially difficult.

Aged↗

Cerebrospinal fluid tau and Abeta42 as predictors of development of Alzheimer's disease in patients with mild cognitive impairment.

We studied CSF-tau and CSF-Abeta42 in 16 patients with mild cognitive impairment (MCI) who at follow-up investigations 6-27 months later had progressed to Alzheimer's disease (AD) with dementia. For comparison, we studied 15 age-matched healthy individuals. At baseline, 14/16 (88%) of MCI patients had high CSF-tau and/or low CSF-Abeta42 levels. These findings show that these CSF-markers are abnormal before the onset of clinical dementia and that they may help to identify MCI patients that will develop AD. This is especially important when drugs with potential effects on the progression of AD will reach the clinical phase.

Aged↗

Decreased protein level of nicotinic receptor alpha7 subunit in the frontal cortex from schizophrenic brain.

The alpha7 subunit of nicotinic receptor (nAChR) was investigated in post-mortem brain tissue from eight schizophrenics and eight age-matched controls by Western blot. Using anti-alpha7 antibodies a single band with a mol. wt of 42 kDa was detected in human post-mortem brain, which was smaller in size than the single band (52 kDa) detected in SH-SY5Y and PC12 cells. The smaller band specifically bound to [125I]alpha-bungarotoxin, confirming the specificity of the detection in the human brain samples. A significant decrease in the level of alpha7 subunit protein was observed with the same method in the frontal cortex of schizophrenics compared with controls, while no difference was found in the parietal cortex. These findings suggest that a deficit of nAChR alpha7 subunit in the frontal cortex might be involved in the pathophysiology of schizophrenia.

Adult↗

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

OBJECTIVE: To evaluate CSF levels of beta-amyloid(1-42) (Abeta42) alone and in combination with CSF tau for distinguishing AD from other conditions. METHODS: At 10 centers in Europe and the United States, 150 CSF samples from AD patients were analyzed and compared with 100 CSF samples from healthy volunteers or patients with disorders not associated with pathologic conditions of the brain (CON), 84 patients with other neurologic disorders (ND), and 79 patients with non-Alzheimer types of dementia (NAD). Sandwich ELISA techniques were used on site for measuring Abeta42 and tau. RESULTS: Median levels of Abeta42 in CSF were significantly lower in AD (487 pg/mL) than in CON (849 pg/mL; p = 0.001), ND (643 pg/mL; p = 0.001), and NAD (603 pg/mL; p = 0.001). Discrimination of AD from CON and ND was significantly improved by the combined assessment of Abeta42 and tau. At 85% sensitivity, specificity of the combined test was 86% (95% CI: 81% to 91%) compared with 55% (95% CI: 47% to 62%) for Abeta42 alone and 65% (95% CI: 58% to 72%) for tau. The combined test at 85% sensitivity was 58% (95% CI: 47% to 69%) specific for NAD. The APOE e4 gene load was negatively correlated with Abeta42 levels not only in AD but also in NAD. CONCLUSIONS: The combined measure of CSF Abeta42 and tau meets the requirements for clinical use in discriminating AD from normal aging and specific neurologic disorders.

Adult↗

Neurofilament protein levels in CSF are increased in dementia.

The neurofilament is the major cytoskeletal structure of myelinated axons. In this study, CSF levels of the light subunit of the neurofilament protein (NFL) were increased in patients with vascular dementia (VAD), AD, and frontotemporal dementia (FTD) compared with neurologically healthy individuals. Because NFL is localized mainly in myelinated axons, these results suggest that the degeneration of white matter in these disorders causes the increased CSF NFL levels.

Aged↗

Characterization of proteins from human cerebrospinal fluid by a combination of preparative two-dimensional liquid-phase electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

To purify and characterize low-abundance proteins in complex biological mixtures, we used a novel strategy that combined preparative two-dimensional liquid-phase electrophoresis (2D-LPE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Preparative 2D-LPE is based on the same isoelectric focusing and gel electrophoresis principles as the widely used analytical 2D gel electrophoresis, except that analytes remain in solution throughout separation. This novel approach shows many improvements compared to analytical 2D gel electrophoresis for the separation of proteins in biological fluids. For example, larger volumes/amounts of samples can be loaded, yielding sufficient amounts of low-abundance proteins for further characterization. Since proteins remain in liquid phase during the entire procedure, extra steps such as electroelution, extraction, or transfer to membranes from the gels prior to mass spectrometric analysis are obviated. We report the usefulness of 2D-LPE combined with MALDI-TOF MS for the purification and characterization of cystatin C and beta-2 microglobulin in human cerebrospinal fluid. This method should be applicable to a wide range of biological fluids, such as cerebrospinal fluid, serum, tissue extracts, cell media, whole cells, and bacterial lysates.

Cerebrospinal Fluid Proteins↗

Cerebrospinal fluid beta-amyloid(1-42) in Alzheimer disease: differences between early- and late-onset Alzheimer disease and stability during the course of disease.

OBJECTIVES: To study the diagnostic potential of the 42 amino acid form of beta-amyloid (beta-amyloid(1-42)) in cerebrospinal fluid (CSF) as a biochemical marker for Alzheimer disease (AD), the intra-individual biological variation of CSF-beta-amyloid(1-42) level in patients with AD, and the possible effects of differential binding between beta-amyloid and apolipoprotein E isoforms on CSF-beta-amyloid(1-42) levels. DESIGN: A 20-month prospective follow-up study. SETTING: Community population-based sample of consecutive patients with AD referred to the Piteå River Valley Hospital, Piteå, Sweden. PATIENTS: Fifty-three patients with AD (mean +/- SD age, 71.4 +/- 7.4 years) diagnosed according to the National Institute of Neurological and Communicative Disorders and Stroke and Alzheimer's Disease and Related Disorders Association criteria and 21 healthy, age-matched (mean +/- SD age, 68.8 +/- 8.0 years) control subjects. MAIN OUTCOME MEASURES: Cerebrospinal fluid beta-amyloid(1-42) level--analyzed using enzyme-linked immunosorbent assay--and severity of dementia--analyzed using the Mini-Mental State Examination. RESULTS: Mean +/- SD levels of CSF-beta-amyloid(1-42) were decreased (P<.001) in patients with AD (709 +/- 304 pg/mL) compared with controls (1678 +/- 436 pg/mL). Most patients with AD (49 [92%] of 53 patients) had reduced levels (<1130 pg/mL). A highly significant correlation (r = 0.90; P<.001) between baseline and 1-year follow-up CSF-beta-amyloid(1-42) levels was found. There were no significant correlations between CSF-beta-amyloid(1-42) level and duration (r = -0.16) or severity (r = -0.02) of dementia. Low levels were also found in patients with mild dementia (Mini-Mental State Examination score, >25). CONCLUSIONS: The sensitivity of CSF-beta-amyloid(1-42) level as a diagnostic marker for AD is high. The intra-individual biological variation in CSF-beta-amyloid(1-42) level is low. Low CSF-beta-amyloid(1-42) levels are also found in the earlier stages of dementia in patients with AD. These findings suggest that CSF-beta-amyloid(1-42) analyses may be of value in the clinical diagnosis of AD, especially in the early course of the disease, when drug therapy may have the greatest potential of being effective but clinical diagnosis is particularly difficult.

Aged↗

Removal of sodium dodecyl sulfate from protein samples prior to matrix-assisted laser desorption/ionization mass spectrometry.

Sodium dodecyl sulfate (SDS) is widely used for protein solubilization and for separation of proteins by SDS polyacrylamide gel electrophoresis (SDS-PAGE). However, SDS interferes with other techniques used for characterization of proteins, such as mass spectrometry (MS) and amino acid sequencing. In this paper, we have compared three procedures to remove SDS from proteins, including chloroform/methanol/water extraction (C/M/W), cold acetone extraction and desalting columns, in order to find a rapid and reproducible procedure that provides sufficient reduction of SDS and high recovery rates for proteins prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). A 1000-fold reduction of SDS concentration and a protein recovery at approximately 50% were obtained with the C/M/W procedure. The cold acetone procedure gave a 100-fold reduction of SDS and a protein recovery of approximately 80%. By using desalting columns, the removal of SDS was 100-fold, with a protein recovery of nearly 50%. Both the C/M/W and the cold acetone methods provided sufficient reduction of SDS, high recovery rates of protein and allowed the acquisition of MALDI spectra. The use of n-octyl-beta-D-glucopyranoside in the protein sample preparation enhanced the MALDI signal for protein samples containing more than 2 10(-4)% SDS, after the C/M/W extraction. Following the cold acetone procedure, the use of n-octylglucoside was found to be necessary in order to obtain spectra, but they were of lower quality than those obtained with the C/M/W method, probably due to higher residual amounts of SDS.

Acetone↗