An outbreak of neuropathies among Berlin solvent sniffers was closely related to the denaturation by methyl-ethyl-ketone (MEK) of the mixture used. The solvent was composed of n-hexane, toluene and ethyl-acetate. Nervous system responses to chronic repeated exposure to 10,000 ppm pure n-hexane, 10,000 ppm MEK/n-hexane (ratio 1:9) and 6000 ppm pure MEK were investigated in rats. Motor neuropathy of the dying back type with giant swelling of axons in the peripheral and central nervous system developed in animals exposed to MEK/n-hexane and n-hexane. Severe potentiation of n-hexane neurotoxicity and shortened onset of morphological and clinical signs were demonstrated in animals exposed to MEK/n-hexane. MEK alone did not produce neuropathy under these conditions. The findings suggest that commercial solvent mixtures containing MEK/n-hexane should be avoided.
Serum alpha-tocopherol and retinol concentrations were followed in four heterozygous adults and one homozygous child with familial hypercholesterolemia being treated by regular low-density lipoprotein (LDL) apheresis. Approximately 50% of plasma alpha-tocopherol was eliminated during a single apheresis procedure in the heterozygous adults, while a complete elimination of this vitamin along with LDLs was observed in the homozygous child. Absolute losses of alpha-tocopherol amounted to 13.4-22.5 mg/apheresis and are equivalent to the recommended dietary intake for 1.5 to 2 days. Despite these losses, no changes were observed either in serum alpha-tocopherol levels or in the ratio of alpha-tocopherol/total serum lipids after 12 months regular apheresis treatment. Serum retinol concentrations only showed a small decrease on apheresis, there being apparently no specific elimination of this vitamin. The absolute losses ranged from 42-422 micrograms/apheresis and were, therefore, much lower than the recommended dietary intake of the equivalent of 1500 micrograms retinol/day. It is concluded that no extra supplementation of these vitamins is required during LDL-apheresis therapy, although it may be advisable to monitor vitamin E status in patients on long-term, intensive therapy.
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