Early effects of X-irradiation on central nerve fibres

Although there have been a number of morphological studies of the late effects of radiation on the brain and spinal cord, early changes in central nerve fibres have not been adequately evaluated. The occurrence of delayed necrosis of the cord months or years after therapeutic doses of radiation is well-recognized (Boden, 1948; Jellinger and Sturm, 1971) and has been attributed to the induction of somatic mutations in interstitial cells (Zeman, 1966). Since transient neurological symptoms consisting of “electrical” paraesthesiae on neck flexion may occur soon after irradiation in man (Jones, 1964), we decided to look for morphological changes in the nerve fibres in the cord in the early stages after experimental irradiation using the particularly sensitive technique of isolation of single nerve fibres (McDonald and Ohlrich, 1971), together with light and electron microscopic examination of cord sections

Nodal changes during the early stages of Wallerian degeneration of central nerve fibres

The nodal changes in central nerve fibres undergoing Wallerian degeneration have been studied during the first 48 hr after section of the dorsal columns of the rat by single fibre teasing and by conventional light and electron microscopic techniques. The earliest changes found at 24 hr consisted of an accumulation of mitochondria, other organelles and lamellar bodies in the nodal axoplasm. Attenuation of the myelin sheath on one side of the node due to detachment of terminal myelin loops and slipping of the outer myelin lamellae was found in some fibres, and varying degrees of nodal widening in others at 24 hr. The functional significance of these early changes in the nodal region is uncertain

Effects of X-Radiation on the spinal cord: An experimental study of the morphological changes in central nerve fibres

Although the mature central nervous system (CNS) is relatively radioresistant in comparison to other tissues (Warren, 1943), under certain circumstances exposure of the CNS to radiation may result in structural damage which may be severe and irreversible..

MRI studies relevant to the pathology and pathogenesis of MS

No abstract availabl

Spasmodic torticollis due to a midbrain lesion in a case of multiple sclerosis

A case of multiple sclerosis is described in which spasmodic torticollis occurred abruplty and abated after 1 year. Magnetic resonance imaging (MRI) demonstrated a lesion in the mesencephalon. Other symptoms and physical signs that developed at the same time as the spasmodic torticollis were compatible with the lesion that had not been present on MRI 18 months previously. There are very few reports of spasmodic torticollis due to an identified focal lesion; there is evidence form experimental work on animals that midbrain lesions may cause spasmodic torticollis but there has been no previous human example

Magnetic crosstalk compensation for an optical current transducer

In this paper we analyse the errors associated with magnetic cross-talk within point type, or unlinked, Optical Current Transducers (OCTs) working in the three-phase electric current transmission systems. It is shown that, for most practical conductor arrangements, the magnetic cross-talk is sufficient to introduce errors unacceptable for the accuracy requirements demanded front the OCT. A solution to this problem is devised around a unique compensation method which solves, in real time, a set of linear equations, each representing the instantaneous output signal from one phase current sensor. The equations are created using calibration factors which can be evaluated for the particular conductors arrangement using experimental or analytical methods. The solution of the above set of equations may be implemented using Digital Signal Processing (DSP), which provides the number of sought instantaneous values of currents in the considered conductors arrangement

Harmonic analysis of current waveforms using optical current sensor

This work reports on the research and development of an optical current sensor for harmonic analysis within the electricity supply network. The device has a measurement capability, limited by the sampling frequency of the A/D converter, to around 20 kHz. We report on experimental verification of these measurements up to the 80th harmonic (4 kHz)