Two-hundred and forty healthy sheep and 32 cases of natural scrapie in Norway were analysed for disease-linked polymorphisms in the prion protein (PrP) gene. Scrapie was strongly associated with the presence of a valine polymorphism at codon 136 (V 136 ), as 68n8 % of the cases were homozygous (VV 136 ) and 15n6 % were valine/alanine heterozygous (VA 136 ). All cases were homozygous arginine/arginine at codon 154 (RR 154 ), except two which were homozygous histidine/histidine (HH 154 ). All cases except two were homozygous glutamine/glutamine at codon 171 (QQ 171 ), the two exceptions being heterozygous glutamine/arginine (QR 171 ). More than 80 % of all scrapie cases in Norway have occurred in a Cheviot-related crossbred type of sheep called Rygja. This type of sheep, which is largely restricted to the south-western coast, carries the V 136 allele at a higher frequency than do other breeds of Norwegian sheep. Polymorphisms at codons 138 and 151 are also described.

Polyamine induced aggregation of various DNAs has been studied under conditions usually employed in many enzymatic assays where DNA is one of the substrates. Spermine was by far the most efficient polyamine in causing aggregation followed by spermidine and cadaverine. All double-stranded and naturally occurring single-stranded DNAs were found to aggregate. No aggregation of single-stranded homodeoxypolymers could be detected under the same conditions. The concentration of polyamine at which the aggregation commenced was found to be a linear function of the DNA concentration. The slope of the curves depended on the nature of the polyamine, DNA the concentration of Mg++ and the ionic strength.

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Plasma total homocysteine response was compared in four groups of healthy individuals given orally divided doses of vitamin supplementations for a duration of 5 weeks. The vitamin supplements; A, 0.3 mg folic acid; B, 120 mg vitamin B6; C, combination of 0.3 mg folic acid and 120 mg vitamin B6 or D, 0.6 mg folic acid reduced the concentrations of plasma total homocysteine 20, 17, 32 and 24%, respectively. However, the intergroup comparisons did not show a significant difference in the effects of vitamin supplements. Multivariate analysis with correction for differences in pre-supplement values indicated a significant effect of vitamin B6 supplementation on plasma total homocysteine and serum folate. Our data show that plasma total homocysteine concentrations are reduced with low to medium divided doses of folic acid alone or in combination with vitamin B6.

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