Conduction Block Due To Demyelination At The Ventral Root Exit Zone In Experimental Allergic Encephalomyelitis

Histological and electrophysiological studies were performed in Lewis rats with experimental allergic encephalomyelitis (EAE) to determine the cause of the neurological signs. The ventral root exit zone of the spinal cord was shown to be a major site of demyelination and conduction block. It is concluded that demyelination-induced conduction block in this region is an important cause of hind-limb weakness and paralysis in Lewis rats with EAE

A call to action for conducting research with people with profound and multiple learning disabilities

People with PMLD are marginalised in society. This marginalisation extends to research, and people with PMLD are often the ‘subjects’ of university studies. This means that research is often done ‘on’ people with PMLD rather than ‘with’ them and with those involved in their care. In this article we describe our vision for a new research agenda. We are developing a research network run by disabled people, for disabled people. We want to explore how people with PMLD and their families/carers/allies can be involved in conducting research that matters to them

Two-Component Scaling near the Metal-Insulator Bifurcation in Two-Dimensions

We consider a two-component scaling picture for the resistivity of two-dimensional (2D) weakly disordered interacting electron systems at low temperature with the aim of describing both the vicinity of the bifurcation and the low resistance metallic regime in the same framework. We contrast the essential features of one-component and two-component scaling theories. We discuss why the conventional lowest order renormalization group equations do not show a bifurcation in 2D, and a semi-empirical extension is proposed which does lead to bifurcation. Parameters, including the product $z\nu$, are determined by least squares fitting to experimental data. An excellent description is obtained for the temperature and density dependence of the resistance of silicon close to the separatrix. Implications of this two-component scaling picture for a quantum critical point are discussed.Comment: 7 pages, 1 figur

Involvement of the Dorsal Root Ganglion in Acute Experimental Allergic Encephalomyelitis in the Lewis Rat - A Histological and Electrophysiological Study

Histological and electrophysiological studies were performed in Lewis rats with acute experimental allergic encephalomyelitis (EAE) in order to determine the extent of dorsal root ganglion (DRG) involvement. Histological studies showed inflammation and demyelination in both the central nervous system (CNS) and peripheral nervous system (PNS). The DRG was the most affected region of the PNS and its involvement increased caudally. Nerve conduction abnormalities were demonstrated in the regions of the lumbar, sacral or coccygeal DRGs in some of the rats with EAE. However, the overall DRG involvement was much less severe, both histologically and functionally, than what we recently found in rabbits with EAE. Conduction through the lumbar dorsal root entry zone was normal. We conclude that lesions of the afferent pathway to the spinal cord do not contribute significantly to the disturbances of hindlimb motor function in Lewis rats with EAE

Ascending Impairment of Nociception in Rats with Experimental Allergic Encephalomyelitis

An ascending impairment of tail nociception is a previously undescribed clinical sign of acute experimental allergic encephalomyelitis (EAE) in the rat. It occurs in EAE induced by inoculation with purified central nervous system (CNS) myelin basic protein (MBP) as well as with whole spinal cord. It is invariably present and consists of an absence of the vocalization response to noxious mechanical stimulation of the tail. This impairment of nociception evolves over 1-3 days, simultaneously with the development of tail weakness, and resolves more rapidly than the tail weakness. Light-microscopic, electron-microscopic and electrophysiological studies indicate that it is due to demyelination-induced conduction block in the small diameter myelinated afferent (A delta) fibres in the sacral and coccygeal dorsal root ganglia, dorsal roots and dorsal root entry zones. Unmyelinated fibres appear to be largely spared

Pedagogies for the 'dis‐engaged': diverse experiences of the young people’s Arts Award programme

Art education is often praised for its engaging programmes and inclusive pedagogies, with many initiatives created with the intention of widening access for those who are deemed to be lacking. This article investigates one such programme – the young people’s Arts Award, which is a nationally recognised qualification for young people aged 11–25. I call upon a range of pedagogies in order to critique the Arts Award within the context of informal and alternative education settings in the United Kingdom. Drawing on a 12‐month ethnographic study, the research was conducted across five diverse programmes which included youth work projects and alternative provision. I present two cases – ‘learning to be an artist’ and ‘learning to behave’ – which demonstrate a hierarchy of pedagogy in the application of this programme across these particular contexts. Artists’ Signature Pedagogies are used as an analytical framework to explore the affordances of working with artists through the programme. Further, I engage with the Pedagogy of Poverty to demonstrate that young people who were classified as ‘dis‐engaged’ were more likely to receive lower quality programmes, low‐level work and over‐regulated teaching. I argue that despite changes to the ways that young people access art education, there continues to be unequal opportunities. This finding is significant for not only creative practitioners and youth arts workers, but also arts education policy makers and programmers

Demyelination and Neurological Signs in Experimental Allergic Encephalomyelitis

Because of the reported absence of demyelination in some animals with neurological signs of experimental allergic encephalomyelitis (EAE), it has been suggested that these signs are not due to demyelination. The present study demonstrates that there is ample demyelination in the central nervous system (CNS) and peripheral nervous system (PNS) to account for the neurological signs in rats with myelin basic protein (MBP)-induced acute EAE as well as in rats and rabbits with whole-spinal-cord-induced acute EAE. The main reasons for failure to detect demyelination in animals with neurological signs of EAE appear to be inadequate histological techniques and incomplete examination of the nervous system, particularly the PNS and the lumbar, sacral and coccygeal segments of the spinal cord

The relative importance of electron-electron interactions compared to disorder in the two-dimensional "metallic" state

The effect of substrate bias and surface gate voltage on the low temperature resistivity of a Si-MOSFET is studied for electron concentrations where the resistivity increases with increasing temperature. This technique offers two degrees of freedom for controlling the electron concentration and the device mobility, thereby providing a means to evaluate the relative importance of electron-electron interactions and disorder in this so-called ``metallic'' regime. For temperatures well below the Fermi temperature, the data obey a scaling law where the disorder parameter ($k_{\rm{F}}l$), and not the concentration, appears explicitly. This suggests that interactions, although present, do not alter the Fermi-liquid properties of the system fundamentally. Furthermore, this experimental observation is reproduced in results of calculations based on temperature-dependent screening, in the context of Drude-Boltzmann theory.Comment: 5 pages, 6 figure

Metallicity and its low temperature behavior in dilute 2D carrier systems

We theoretically consider the temperature and density dependent transport properties of semiconductor-based 2D carrier systems within the RPA-Boltzmann transport theory, taking into account realistic screened charged impurity scattering in the semiconductor. We derive a leading behavior in the transport property, which is exact in the strict 2D approximation and provides a zeroth order explanation for the strength of metallicity in various 2D carrier systems. By carefully comparing the calculated full nonlinear temperature dependence of electronic resistivity at low temperatures with the corresponding asymptotic analytic form obtained in the $T/T_F \to 0$ limit, both within the RPA screened charged impurity scattering theory, we critically discuss the applicability of the linear temperature dependent correction to the low temperature resistivity in 2D semiconductor structures. We find quite generally that for charged ionized impurity scattering screened by the electronic dielectric function (within RPA or its suitable generalizations including local field corrections), the resistivity obeys the asymptotic linear form only in the extreme low temperature limit of $T/T_F \le 0.05$. We point out the experimental implications of our findings and discuss in the context of the screening theory the relative strengths of metallicity in different 2D systems.Comment: We have substantially revised this paper by adding new materials and figures including a detailed comparison to a recent experimen

Acquisition and retention of Clostridium difficile by Musca domestica larvae and pupae during metamorphosis

Background: Transfer of Clostridium difficile by Musca domestica has been demonstrated, revealing their potential for disseminating infection in the hospital environment. Aim: To determine the ability of M. domestica larvae to acquire and retain C. difficile throughout their metamorphosis into adult flies. Methods: Larvae were exposed to spores of C. difficile in a faecal emulsion and examined externally and internally to determine carriage and internalisation of spores through their development to adults. Findings: Larvae harboured C. difficile externally, with means of 21.56 +/- 5.76 CFUs at day zero, 22.44 +/- 9.90 after two days, decreasing to 0.56 +/- 0.34 at day four, with no C. difficile isolated thereafter. The same larvae harboured C. difficile internally, with means of 587.33 +/- 238.29 CFUs at day zero, decreasing to 297.44 +/- 155.21 after two days, decreasing further to 73.67 +/- 46.74 after four days, with no C. difficile isolated thereafter. The zero recovery of C. difficile coincided with the development of M. domestica larvae into pupae. From day six onwards, all larvae had developed into the pupal stage and no C. difficile was recoverable from any pupae. No C. difficile was recovered from adult flies (emerged on day twelve), or empty puparia. Conclusion: Although C. difficile spores are readily acquired and internalised by larvae during feeding, they are not retained through development to adults. Adult flies therefore acquire C. difficile contamination as adults. The potential antimicrobial action of M. domestica larvae and their extracts against C. difficile spores warrants further investigation