Comparing teacher roles in Denmark and England

This article reports the findings of a comparative study of teaching in Denmark and England; its broader aim is to help develop an approach for comparing pedagogy. Lesson observations and interviews identified the range of goals towards which teachers in each country worked and the actions these prompted. These were clustered using the lens of Bernstein’s pedagogic discourse (1990; 1996) to construct teacher roles which provided a view of pedagogy. Through this approach we have begun to identify variations in pedagogy across two countries. All teachers in this study adopted a variety of roles; of significance was the ease with which competent English teachers moved between roles. The English teachers observed adopted roles consistent with a wider techno-rationalist discourse. There was a greater subject emphasis by Danish teachers whose work was set predominantly within a democratic humanist discourse, whilst the English teachers placed a greater emphasis on applied skills

Deposition of C-terminally truncated A beta species A beta 37 and A beta 39 in Alzheimer's disease and transgenic mouse models

In Alzheimer's disease (AD) a variety of amyloid beta-peptides (A beta) are deposited in the form of extracellular diffuse and neuritic plaques (NP), as well as within the vasculature. The generation of A beta from its precursor, the amyloid precursor protein (APP), is a highly complex procedure that involves subsequent proteolysis of APP by beta-and gamma-secretases. Brain accumulation of A beta due to impaired A beta degradation and/or altered ratios between the different A beta species produced is believed to play a pivotal role in AD pathogenesis. While the presence of A beta 40 and A beta 42 in vascular and parenchymal amyloid have been subject of extensive studies, the deposition of carboxyterminal truncated A beta peptides in AD has not received comparable attention. In the current study, we for the first time demonstrate the immunohistochemical localization of A beta 37 and A beta 39 in human sporadic AD (SAD). Our study further included the analysis of familial AD (FAD) cases carrying the APP mutations KM670/671NL, E693G and I716F, as well as a case of the PSEN1 Delta Exon9 mutation. A beta 37 and A beta 39 were found to be widely distributed within the vasculature in the brains of the majority of studied SAD and FAD cases, the latter also presenting considerable amounts of A beta 37 containing NPs. In addition, both peptides were found to be present in extracellular plaques but only scarce within the vasculature in brains of a variety of transgenic AD mouse models. Taken together, our study indicates the importance of C-terminally truncated A beta in sporadic and familial AD and raises questions about how these species are generated and regulated.Peer reviewe

Development and Technical Validation of an Immunoassay for the Detection of APP669−711 (Aβ−3−40) in Biological Samples

The ratio of amyloid precursor protein (APP)669–711 (Aβ−3–40)/Aβ1–42 in blood plasma was reported to represent a novel Alzheimer’s disease biomarker. Here, we describe the characterization of two antibodies against the N-terminus of Aβ−3–x and the development and “fit-for-purpose” technical validation of a sandwich immunoassay for the measurement of Aβ−3–40. Antibody selectivity was assessed by capillary isoelectric focusing immunoassay, Western blot analysis, and immunohistochemistry. The analytical validation addressed assay range, repeatability, specificity, between-run variability, impact of pre-analytical sample handling procedures, assay interference, and analytical spike recoveries. Blood plasma was analyzed after Aβ immunoprecipitation by a two-step immunoassay procedure. Both monoclonal antibodies detected Aβ−3–40 with no appreciable cross reactivity with Aβ1–40 or N-terminally truncated Aβ variants. However, the amyloid precursor protein was also recognized. The immunoassay showed high selectivity for Aβ−3–40 with a quantitative assay range of 22 pg/mL–7.5 ng/mL. Acceptable intermediate imprecision of the complete two-step immunoassay was reached after normalization. In a small clinical sample, the measured Aβ42/Aβ−3–40 and Aβ42/Aβ40 ratios were lower in patients with dementia of the Alzheimer’s type than in other dementias. In summary, the methodological groundwork for further optimization and future studies addressing the Aβ42/Aβ−3–40 ratio as a novel biomarker candidate for Alzheimer’s disease has been set

Automated Capillary Electrophoresis Immunoblot for the Detection of Alpha-Synuclein in Mouse Tissue

Background: Alpha-synuclein (aSyn) is a key player in neurodegenerative diseases such as Parkinson’s disease (PD), dementia with Lewy bodies, or multiple system atrophy. aSyn is expressed throughout the brain, and can also be detected in various peripheral tissues. In fact, initial symptoms of PD are non-motoric and include autonomic dysfunction, suggesting that the periphery might play an important role in early development of the disease. aSyn is expressed at relatively low levels in non-central tissues, which brings challenges for its detection and quantification in different tissues. Objective: Our goal was to assess the sensitivity of aSyn detection in central and peripheral mouse tissues through capillary electrophoresis (CE) immunoblot, considering the traditional SDS-PAGE immunoblot as the current standard. Methods: Tissues from central and non-central origin from wild type mice were extracted, and included midbrain, inner ear, and esophagus/stomach. aSyn detection was assessed through immunoblotting using Simple Western size-based CE and SDS-PAGE. Results: CE immunoblots show a consistent detection of aSyn in central and peripheral tissues. Through SDS-PAGE, immunoblots revealed a reliable signal corresponding to aSyn, particularly following membrane fixation. Conclusion: Our results suggest a reliable detection of aSyn in central and peripheral tissues using the CE Simple Western immunoblot system. These observations can serve as preliminary datasets when aiming to formally compare CE with SDS-PAGE, as well as for further characterization of aSyn using this technique

N-truncated Aβ4–x peptides in sporadic Alzheimer’s disease cases and transgenic Alzheimer mouse models

Abstract Background The deposition of neurotoxic amyloid-β (Aβ) peptides in plaques in the brain parenchyma and in cerebral blood vessels is considered to be a key event in Alzheimer’s disease (AD) pathogenesis. Although the presence and impact of full-length Aβ peptides such as Aβ1–40 and Aβ1–42 have been analyzed extensively, the deposition of N-terminally truncated Aβ peptide species has received much less attention, largely because of the lack of specific antibodies. Methods This paper describes the generation and characterization of novel antibodies selective for Aβ4–x peptides and provides immunohistochemical evidence of Aβ4–x in the human brain and its distribution in the APP/PS1KI and 5XFAD transgenic mouse models. Results The Aβ4–x staining pattern was restricted mainly to amyloid plaque cores and cerebral amyloid angiopathy in AD and Down syndrome cases and in both AD mouse models. In contrast, diffuse amyloid deposits were largely negative for Aβ4–x immunoreactivity. No overt intraneuronal staining was observed. Conclusions The findings of this study are consistent with previous reports demonstrating a high aggregation propensity of Aβ4–x peptides and suggest an important role of these N-truncated Aβ species in the process of amyloidogenesis and plaque core formation