Differential effects of basolateral and apical iron supply on iron transport in Caco-2 cells.

Iron homeostasis in the human body is maintained primarily through regulation of iron absorption in the duodenum. The liver peptide hepcidin plays a central role in this regulation. Additionally, expression and functional control of certain components of the cellular iron transport machinery can be influenced directly by the iron status of enterocytes. The significance of this modulation, relative to the effects of hepcidin, and the comparative effects of iron obtained directly from the diet and/or via the bloodstream are not clear. The studies described here were performed using Caco-2 cell monolayers as a model of intestinal epithelium, to compare the effects of iron supplied in physiologically relevant forms to either the apical or basolateral surfaces of the cells. Both sources of iron provoked increased cellular ferritin content, indicating iron uptake from both sides of the cells. Supply of basolateral transferrin-bound iron did not affect subsequent iron transport across the apical surface, but reduced iron transport across the basolateral membrane. In contrast, the apical iron supply led to subsequent reduction in iron transport across the apical cell membrane without altering iron export across the basolateral membrane. The apical and basolateral iron supplies also elicited distinct effects on the expression and subcellular distribution of iron transporters. These data suggest that, in addition to the effects of cellular iron status on the expression of iron transporter genes, different modes and direction of iron supply to enterocytes can elicit distinct functional effects on iron transport.

Congenital cervical spinal muscular atrophy: a non-familial, non progressive condition of the upper limbs.

Two patients with congenital cervical spinal muscular atrophy had symmetrical severe muscle weakness and wasting confined to the upper limbs, areflexia and congenital contractures. The shoulders were internally rotated, elbows extended and wrists flexed. There were no sensory or bulbar symptoms, scoliosis, long tract signs or lower limb involvement. This condition should be regarded as a neurogenic type of arthrogryposis, limited to the upper limbs.

Is there involvement of the central nervous system in hereditary sensory radicular neuropathy?

There is pathological evidence that hereditary sensory radicular neuropathy (HSN type I) is a disorder related to multi-system atrophy with marked cell loss in the cerebral cortex, thalamus, brain stem and cerebellum. We report here a clinical study of a case of HSN-I including audiometric testing, autonomic functions, electromyography, transcranial magnetic stimulation and magnetic resonance imaging of the brain. There were no signs of central nervous system involvement. It is stated that HSN-I remains a disorder of dorsal root ganglia and sensory nerves, leading to painless perforating ulceration and mutilation, within the course of the disease peripheral motor nerve involvement, but without involvement of central motor pathways.