Revised transthyretin Ile 122 allele frequency in African-Americans

The transthyretin (TTR) Ile 122 variant is associated with cardiac amyloidosis in individuals of African descent. To determine the prevalence of the allele encoding TTR Ile 122 in African-Americans, we have used PCR and restriction analysis to test DNA from African-Americans from various geographic areas, and found an allele frequency of 66/3376 (0.020), which is higher than the value we previously reported in a much smaller pilot study. Our data indicate that this TTR variant is present at equal frequency in African-Americans throughout the U.S., and suggest that this mutation may be a common, often unrecognized cause of cardiac disease in African-Americans.

Enzyme rate assay for 5-fluorocytosine

Modification of an enzyme assay for 5-fluorocytosine, from an end point to a rate analysis, has resulted in a method that can provide results within 10 minutes. The modification also rendered the assay less susceptible to interference from bilirubin and triglycerides. This obviated the need to correct 5-fluorocytosine results for icteric or moderately lipemic samples. The performance history of the enzyme rate method has shown that it is reliable, quick, cost-effective, and suitable for use in a clinical laboratory.

Enriched housing masks deficits in place navigation induced by neonatal monosodium glutamate

Monosodium-L-glutamate (MSG)-induced behavioural deficits were examined under two housing conditions. Male Wistar rat pups were cross-fostered at birth and injected with MSG on days 2 to 11 postpartum. Control pups were injected with saline (Sal) of equivalent volume. Following weaning at day 25 the rats were allocated to either "enriched" (EC) or "impoverished" (IC) housing, thus forming four treatment groups: MSG-EC, MSG-IC, Sal-EC, and Sal-IC. Thirty-five days later all rats were tested in the open field and in the place navigation task. Multivariate analysis of variance (MANOVA) revealed a significant two-way interaction of the housing x drug variables. While the MSG-IC rats were deficient in the water maze, the performance of the MSG-EC approached that of saline-injected controls. Although the Sal-IC rats developed higher body weights than the Sal-EC rats the MSG-EC and MSG-IC rats did not differ in body weight. The housing by drug treatment interaction was not apparent in the open field.

Stimulation of 5-aminolevulinic acid metabolism by uroporphyrinogen I in rat liver homogenate

The effect of excess uroporphyrinogens I and III, coproporphyrinogen III, and the corresponding porphyrins, on the rate of 4-14C-5-aminolevulinic acid (ALA) metabolism was studied. Experiments were performed with mitochondria-free rat liver homogenates prepared from normal rats. The consumption of labelled 5-aminolevulinic acid was followed by measuring its level in aliquots removed at intervals. The pattern of porphyrinogen synthesis was examined by high pressure liquid chromatography. Only uroporphyrinogen I had an effect; it increased the rate of conversion of ALA and porphobilinogen (PBG) to porphyrinogens. Chromatographic analysis revealed increased synthesis of uroporphyrinogen and heptacarboxylic porphyrinogen. It is believed that this mechanism might explain the lack of ALA and PBG accumulation in erythropoietic porphyria and porphyria cutanea tarda, and the absence of acute porphyria attacks in these conditions.

An internal standard for porphyrin analysis

The routine clinical analysis of the porphyrin precursors of heme requires an internal standard to determine the efficiency of the analytical procedure used. 2-Vinyl-4-hydroxymethyldeuteroporphyrin IX has been prepared as an internal standard. Its application to porphyrin analysis has been demonstrated using high-performance liquid chromatographic resolution of the uro- to protoporphyrins in normal and porphyric urine.