Bioavailability Comparison of Nine Bioselenocompounds In Vitro and In Vivo

Selenium (Se) shows biologically ambivalent characteristics in animals. It is an essential element but becomes severely toxic when the amount ingested exceeds the adequate intake level. Its biological, nutritional, and toxicological effects are strongly dependent on its chemical form. In this study, we evaluated the toxicity and bioavailability of nine naturally occurring Se compounds, or the so-called bioselenocompounds, in vivo and in vitro. Selenite and selenocystine showed higher toxicity than the other bioselenocompounds in vitro. In an in vitro membrane permeability study using Caco-2 cells, selenomethionine and Se-methylselenocysteine were more efficiently transported than the other bioselenocompounds. The effect of bioselenocompounds on nutritional availability was quantitatively determined from the recovery of serum selenoproteins in Se-deficient rats by speciation analysis. In contrast to the in vitro study, there were no significant differences in the assimilation of Se into serum selenoproteins among the bioselenocompounds, including selenoamino acids, selenosugar, and inorganic Se species, such as selenite, selenate, and selenocyanate, except trimethylselenonium ion. These results indicate that animals can equally assimilate both inorganic and organic naturally occurring selenocompounds except trimethylselenonium ion, which is the urinary metabolite of excess Se. We confirmed that the bioselenocompounds except trimethylselenonium ion had equivalent nutritional availabilities.

Screening of the GPX3 gene identifies the "T" allele of the SNP -861A/T as a risk for ischemic stroke in young Asian Indians

BACKGROUND

Deficiency of plasma glutathione peroxidase (GPx-3) has been associated with platelet-dependent thrombosis. Single-nucleotide polymorphisms (SNPs) in the promoter region of GPX3 gene have been found associated with the risk for ischemic stroke in Caucasian populations. The aim of our present study was to evaluate the impact of genetic variations in the GPX3 gene and plasma GPx-3 antigen levels on ischemic stroke in young Asian Indians.

METHODS

One hundred patients with ischemic stroke and 200 age- and sex-matched controls were studied. Genetic analysis for the study population was done by a combination of variant screening using single-stranded conformation polymorphism and final genotyping by polymerase chain reaction-restriction fragment length polymorphism and allele-specific polymerase chain reactions. Plasma GPx-3 antigen levels were evaluated using commercial kits. Data were analyzed using genetic analysis software and statistical tools.

RESULTS

Significantly higher GPx-3 levels were observed in controls compared with patients (controls 26.37 ± 3.66 μg/mL and patients 22.83 ± 4.57 μg/mL, P < .001). Only the SNP -861A/T was found associated with stroke phenotype (P < .0001). The SNP -568T/C was observed to significantly influence plasma GPx-3 levels (P < .05). The haplotype carrying the risk "T" allele of SNP -861A/T was significantly over-represented in patients with stroke (P < .0001).

CONCLUSIONS

The T allele of -861A/T is a risk allele for the ischemic stroke phenotype. The -861A/T and -568T/C SNPs may show a statistically significant association with both plasma GPx-3 antigen levels and the stroke phenotype in a larger sample size.