[Anatomy and basic knowledge of the spinal cord]

Basic knowledge of macroscopic anatomy is needed to understand the clinical signs and distinct syndromes resulting from the disturbed function of the tracks, segments and roots of the spinal cord. The cord is contained within the vertebral canal, continuing the medulla down to the conus medullaris. Descending tracks are motor (corticospinal and extrapyramidal), and ascending tracks are sensory (spinothalamic and lemniscal). Spinal cord involvement must be considered when a sensorimotor spinal tract and a radicular spinal syndromes are combined. Syringomyelia, Brown-Séquard syndrome and subacute combined degeneration of the spinal cord must also be familiar to clinicians, as well as how to differentiate a conus medullaris from a cauda equina syndrome.

Ocular motor consequences of damage to the abducens nucleus area in humans

A patient with a complete unilateral conjugate gaze paralysis caused by a small lesion affecting the region of the right abducens nucleus, documented by magnetic resonance imaging, is reported. Eye movements were quantitatively evaluated using electro-oculography. A gaze-evoked nystagmus to the contralateral side and impairment of smooth pursuit and vestibular ocular reflex in the contralateral hemifield of movements were found. The differential diagnosis of conjugate gaze paralysis and the additional ocular motor abnormalities are interpreted in light of clinical and experimental findings.

Anomia for proper names after left thalamic infarct

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Modulation of prion protein gene expression by growth factors in cultured mouse astrocytes and PC-12 cells

The present study was performed on primary cultures of mouse astrocytes and cultures of rat pheochromocytoma PC-12 in order to investigate the regulation of the prion protein (PrP) gene expression in relation to proliferation and differentiation. Treatment of PC-12 cells with interleukin-6 (IL-6) and beta-nerve growth factor (NGF) resulted in induction of neuronal differentiation. Northern blot analysis demonstrated a 4-fold increase of PrP mRNA in relation to cellular differentiation, after 7 days of treatment with either of the two factors. In astrocytes, PrP and glial fibrillary acidic protein (GFAP) mRNA levels were found to be regulated in a similar manner during development in vitro. A 3-fold increase of their mRNAs was observed from 5 to 14 days of culture (proliferation period). Then, their gene expressions showed a slight decrease from 14 to 28 days (maturation period). Treatment of astrocytes with IL-6, basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF) appeared to markedly down-regulate the expression of GFAP mRNAs, which might reflect cell maturation. In contrast, they had no significant effect on the expression of PrP gene. These results suggest that the PrP gene expression is differently regulated in neural cells. In neuronal cells, it is mainly associated with differentiation. On the other hand, in astrocytes, the PrP mRNA level seems to be not only related to the proliferation and differentiation stages.