Ezra Mulugeta

King's College London, Londinium, England, United Kingdom

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Publications (14)75.16 Total impact

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    ABSTRACT: Damage to sub-cortical white matter is a key substrate of vascular dementia (VaD) leading to deficits in executive function and cognitive processing speed. Dynamin1 is a 100kDa protein, accounting for 0.4% of the total brain protein, and has a central role in many intracellular processes such as synaptic vesicle trafficking and recycling. In this study, we examined the status of Dynamin1 in the white matter from frontal cortex area. In order to measure the levels of Dynamin1, we isolated cortical white matter from a total of 34 post-mortem brains derived from controls (N=11), mixed Alzheimer's Disease (AD) and VaD (N=8), VaD (N=7), and Stroke no Dementia (SND, N=8) subjects. A commercial ELISA kit was then used to determine the level of Dynamin1. In comparison to controls, Dynamin 1 was elevated in patients SND (+400%) and reduced in patients with mixed VaD (-50%). Furthermore, levels of Dynamin 1 were significantly associated with preserved cognition as indicated by the MMSE and CAMCOG and upregulation of vesicular Glutamate transporter 1. This work indicates that Dynamin 1 is associated with both preserved cognition and regenerative responses in older people with cerebrovascular disease and may represent a novel treatment target.
    Neuroscience Letters 01/2014; · 2.03 Impact Factor
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    ABSTRACT: Core CSF changes in Alzheimer disease (AD) are decreased amyloid β(1-42), increased total tau, and increased phospho-tau, probably indicating amyloid plaque accumulation, axonal degeneration, and tangle pathology, respectively. These biomarkers identify AD already at the predementia stage, but their diagnostic performance might be affected by age-dependent increase of AD-type brain pathology in cognitively unaffected elderly. We investigated effects of age on the diagnostic performance of CSF biomarkers in a uniquely large multicenter study population, including a cross-sectional cohort of 529 patients with AD dementia (median age 71, range 43-89 years) and 304 controls (67, 44-91 years), and a longitudinal cohort of 750 subjects without dementia with mild cognitive impairment (69, 43-89 years) followed for at least 2 years, or until dementia diagnosis. The specificities for subjects without AD and the areas under the receiver operating characteristics curves decreased with age. However, the positive predictive value for a combination of biomarkers remained stable, while the negative predictive value decreased only slightly in old subjects, as an effect of the high AD prevalence in older ages. Although the diagnostic accuracies for AD decreased with age, the predictive values for a combination of biomarkers remained essentially stable. The findings highlight biomarker variability across ages, but support the use of CSF biomarkers for AD even in older populations.
    Neurology 02/2012; 78(7):468-76. · 8.25 Impact Factor
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    ABSTRACT: We wanted to assess whether biomarkers abeta42, tau and p-tau could differentiate between Alzheimer's disease and other dementia illnesses. Following systematic Pubmed searches, 25 articles which reported sensitivity and specificity for Alzheimer's disease and other dementias were included. Most studies showed significant differences for all three markers between Alzheimer's disease and other dementia illnesses, except abeta42 which did not differ between Alzheimer's disease and dementia with Lewy bodies. Alzheimer's disease was distinguished from vascular dementia with sensitivities and specificities 77 % - 87 % and 62-80 % (abeta42); 79-100 % and 14-100 % (tau); and 78-80 % and 63-96 % (p-tau181). Alzheimer's disease and dementia with Lewy bodies were differentiated by tau and p-tau181 with sensitivities and specificities of 72-94 % and 53-92 %, and of 68-85 % and 61-85 %. Markers separated Alzheimer's disease from frontal lobe dementia with sensitivities and specificities of 37-91 % and 59-92 % (abeta42), 58-88 % and 68-92 % (tau) and 44-91 % and 79-100 % (p-tau181). Methodological weaknesses impede the interpretation. CSF markers are not yet sufficient to differentiate between Alzheimer's disease and other forms of dementia.
    Tidsskrift for den Norske laegeforening 11/2011; 131(22):2235-8.
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    ABSTRACT: Parkinson's disease (PD) and Dementia with Lewy bodies (DLB) are neurodegenerative diseases that are characterized by intra-neuronal inclusions of Lewy bodies in distinct brain regions. These inclusions consist mainly of aggregated α-synuclein (α-syn) protein. The present study used immunoprecipitation combined with nanoflow liquid chromatography (LC) coupled to high resolution electrospray ionization Fourier transform ion cyclotron resonance tandem mass spectrometry (ESI-FTICR-MS/MS) to determine known and novel isoforms of α-syn in brain tissue homogenates. N-terminally acetylated full-length α-syn (Ac-α-syn₁₋₁₄₀) and two N-terminally acetylated C-terminally truncated forms of α-syn (Ac-α-syn₁₋₁₃₉ and Ac-α-syn₁₋₁₀₃) were found. The different forms of α-syn were further studied by Western blotting in brain tissue homogenates from the temporal cortex Brodmann area 36 (BA36) and the dorsolateral prefrontal cortex BA9 derived from controls, patients with DLB and PD with dementia (PDD). Quantification of α-syn in each brain tissue fraction was performed using a novel enzyme-linked immunosorbent assay (ELISA).
    Neurochemical Research 06/2011; 36(11):2029-42. · 2.13 Impact Factor
  • Alzheimers & Dementia - ALZHEIMERS DEMENT. 01/2011; 7(4).
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    ABSTRACT: We measured cerebrospinal fluid (CSF) levels of the soluble isoforms of amyloid precursor protein (APP; sAPPα sAPPβ) and other CSF biomarkers in 107 patients with Alzheimer's disease (AD), dementia with Lewy body dementia (DLB), Parkinson's disease dementia (PDD), and normal controls (NC) using commercial kits. DLB and PDD were combined in a Lewy body dementia group (LBD). No differences were observed in sAPPα and sAPPβ levels between the groups. Significant correlations were observed between sAPPα and sAPPβ and between sAPPβ and Mini-Mental State Examination scores in the total group analysis as well as when LBD and AD groups were analyzed separately. sAPPα and sAPPβ levels correlated with Aβ38, Aβ40, Aβ42, and Tau in the LBD group. In AD, sAPPα correlated with p-Tau and sAPPβ with Aβ40. The differential association between sAPPα and sAPPβ with Aβ and Tau species between LBD and AD groups suggests a possible relationship with the underlying pathologies in LBD and AD.
    International journal of Alzheimer's disease. 01/2011; 2011:495025.
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    ABSTRACT: The clinical distinction between Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) is sometimes difficult, particularly in mild cases. Although CSF markers such as amyloid β42 (Aβ42) and P-tau can distinguish between AD and normal controls, their ability to distinguish between AD and DLB is not adequate. This study aims to investigate whether CSF markers, in particular levels of Aβ38, can differentiate between mild AD and DLB. 85 individuals were included after standardised diagnostic procedures: 30 diagnosed as probable AD, 23 probable DLB, 20 probable Parkinson's disease dementia and 12 non-demented control subjects. CSF levels of Aβ38, Aβ40 and Aβ42 were determined using commercially available ultra-sensitive multi-array kit assay (MSD) for human Aβ peptides. Total tau (T-tau) and phosphorylated tau (P-tau) were analysed using ELISA (Innotest). In addition, combinations (Aβ42/Aβ38, Aβ42/Aβ40, Aβ42/P-tau and Aβ42/Aβ38/P-tau) were assessed. Significant between group differences were found for all CSF measures, and all except Aβ40, Aβ42 and Aβ42/P-tau differed between AD and DLB. The Aβ42/Aβ38 ratio was the measure that best discriminated between AD and DLB (AUC 0.765; p<0.005), with a sensitivity of 78% and a specificity of 67%. This study suggests that the level of Aβ38 can potentially contribute in the diagnostic distinction between AD and DLB when combined with Aβ42. Single measures had low diagnostic accuracy, suggesting that developing a panel of markers is the most promising strategy. Studies with independent and larger samples and a priori cut-offs are needed to test this hypothesis.
    Journal of neurology, neurosurgery, and psychiatry 11/2010; 82(2):160-4. · 4.87 Impact Factor
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    ABSTRACT: Alzheimer's disease (AD) pathology is found in a considerable portion of patients with Parkinson's disease (PD), particularly those with early dementia (PDD). Altered cerebrospinal fluid (CSF) levels of amyloid-β (Aβ) and tau proteins have been found in PDD, with intermediate changes for Aβ42 in non-demented PD. The authors investigated whether AD-related CSF protein levels are altered and relate to neuropsychological performance in early, untreated PD. CSF concentrations of Aβ42, Aβ40 and Aβ38 were measured by electrochemiluminiscene and levels of total tau (T-tau) and phosphorylated tau (P-tau) by ELISA in 109 newly diagnosed, unmedicated, non-demented, community-based PD patients who had undergone comprehensive neuropsychological testing, and were compared with those of 36 age-matched normal controls and 20 subjects with mild AD. PD patients displayed significant reductions in Aβ42 (19%; p=0.009), Aβ40 (15.5%; p=0.008) and Aβ38 (23%; p=0.004) but not T-tau (p=0.816) or P-tau (p=0.531) compared with controls. CSF Aβ42 reductions in PD were less marked than in AD (53%; p=0.002). Sequential regression analyses demonstrated significant associations between CSF levels of Aβ42 (β=0.205; p=0.019), Aβ40 (β=0.378; p<0.001) and Aβ38 (β=0.288; p=0.001) and memory impairment, but not executive-attentional or visuospatial dysfunction. Tau protein levels did not correlate with cognitive measures. CONCLUSIOn: CSF Aβ levels are altered in a subset of patients with early PD and relate to memory impairment. Our study suggests that alterations in Aβ protein metabolism may contribute to the heterogeneity in pattern and course of cognitive decline associated with PD. Longitudinal studies are needed to clarify the clinical significance of CSF Aβ peptides as prognostic biomarkers in PD.
    Journal of neurology, neurosurgery, and psychiatry 10/2010; 81(10):1080-6. · 4.87 Impact Factor
  • Alzheimer's and Dementia 07/2010; 6(4). · 17.47 Impact Factor
  • Biochemical Pharmacology - BIOCHEM PHARMACOL. 01/2010; 6(4).
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    ABSTRACT: Small single-center studies have shown that cerebrospinal fluid (CSF) biomarkers may be useful to identify incipient Alzheimer disease (AD) in patients with mild cognitive impairment (MCI), but large-scale multicenter studies have not been conducted. To determine the diagnostic accuracy of CSF beta-amyloid(1-42) (Abeta42), total tau protein (T-tau), and tau phosphorylated at position threonine 181 (P-tau) for predicting incipient AD in patients with MCI. The study had 2 parts: a cross-sectional study involving patients with AD and controls to identify cut points, followed by a prospective cohort study involving patients with MCI, conducted 1990-2007. A total of 750 individuals with MCI, 529 with AD, and 304 controls were recruited by 12 centers in Europe and the United States. Individuals with MCI were followed up for at least 2 years or until symptoms had progressed to clinical dementia. Sensitivity, specificity, positive and negative likelihood ratios (LRs) of CSF Abeta42, T-tau, and P-tau for identifying incipient AD. During follow-up, 271 participants with MCI were diagnosed with AD and 59 with other dementias. The Abeta42 assay in particular had considerable intersite variability. Patients who developed AD had lower median Abeta42 (356; range, 96-1075 ng/L) and higher P-tau (81; range, 15-183 ng/L) and T-tau (582; range, 83-2174 ng/L) levels than MCI patients who did not develop AD during follow-up (579; range, 121-1420 ng/L for Abeta42; 53; range, 15-163 ng/L for P-tau; and 294; range, 31-2483 ng/L for T-tau, P < .001). The area under the receiver operating characteristic curve was 0.78 (95% confidence interval [CI], 0.75-0.82) for Abeta42, 0.76 (95% CI, 0.72-0.80) for P-tau, and 0.79 (95% CI, 0.76-0.83) for T-tau. Cut-offs with sensitivity set to 85% were defined in the AD and control groups and tested in the MCI group, where the combination of Abeta42/P-tau ratio and T-tau identified incipient AD with a sensitivity of 83% (95% CI, 78%-88%), specificity 72% (95% CI, 68%-76%), positive LR, 3.0 (95% CI, 2.5-3.4), and negative LR, 0.24 (95% CI, 0.21-0.28). The positive predictive value was 62% and the negative predictive value was 88%. This multicenter study found that CSF Abeta42, T-tau, and P-tau identify incipient AD with good accuracy, but less accurately than reported from single-center studies. Intersite assay variability highlights a need for standardization of analytical techniques and clinical procedures.
    JAMA The Journal of the American Medical Association 08/2009; 302(4):385-93. · 29.98 Impact Factor
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    ABSTRACT: The aim of this study was to explore the relationship between cerebrospinal fluid biomarkers and neuropsychiatric symptoms in people with Alzheimer's disease. Psychosis, agitation, apathy and depression were assessed using standardised measures in 32 patients with mild Alzheimer's disease. The levels of the 42-amino-acid form of beta-amyloid (A beta(1-42)), tau and p-tau (phosphorylated at threonine 181) were quantified using the conventional enzyme-linked immunosorbent assay method. Our result shows that apathy is significantly correlated with tau and p-tau but not with A beta(1-42). There were no significant correlations between indices of psychosis/agitation,or depression and cerebrospinal fluid A beta(1-42), tau or p-tau concentrations. Our finding suggests that apathy is associated with the level of neurofibrillary tangles in people with mild Alzheimer's disease. In contrast, the overall levels of neurofibrillary tangles or amyloid plaques do not seem to be associated with depression or psychosis, indicating that other brain changes contribute to these symptoms.
    Dementia and Geriatric Cognitive Disorders 02/2008; 25(6):559-63. · 2.79 Impact Factor
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    ABSTRACT: Vascular dementia (VaD) accounts for about 20% of all dementias, and vascular risk is a key factor in more than 40% of people with Alzheimer's disease (AD). Little is known about inflammatory processes in the brains of these individuals. We have examined inflammatory mediators (interleukin (IL)-1beta, IL-1alpha, IL-6 and tumour necrosis factor alpha) and chemokines (macrophage inflammatory protein 1, monocyte chemo-attractant protein (MCP)-1 and granulocyte macrophage colony-stimulating factor) in brain homogenates from grey and white matter of the frontal cortex (Brodmann area 9) from patients with VaD (n = 11), those with concurrent VaD and AD (mixed dementia; n = 8) and from age-matched controls (n = 13) using ELISA assays. We found a dramatic reduction of MCP-1 levels in the grey matter in VaD and mixed dementia in comparison to controls (55 and 66%, respectively). IL-6 decreases were also observed in the grey matter of VaD and mixed dementia (72 and 71%, respectively), with a more modest decrease (30%) in the white matter of patients with VaD or mixed dementia. In the first study to examine the status of inflammatory mediators in a brain region severely affected by white-matter lesions, our findings highlight - in contrast to previous reports in AD - that patients at the later stage of VaD or mixed dementia have a significantly attenuated neuro-inflammatory response.
    Dementia and Geriatric Cognitive Disorders 02/2008; 25(3):278-86. · 2.79 Impact Factor
  • Alzheimers & Dementia - ALZHEIMERS DEMENT. 01/2008; 4(4).

Publication Stats

456 Citations
75.16 Total Impact Points

Institutions

  • 2008–2014
    • King's College London
      • Wolfson Centre for Age-Related Diseases
      Londinium, England, United Kingdom
  • 2010–2011
    • Stavanger University Hospital
      Stavenger, Rogaland, Norway
  • 2008–2011
    • University of Bergen
      • • Department of Clinical Medicine
      • • Institute of Medicine
      Bergen, Hordaland Fylke, Norway