Fate of selenium in soil: A case study in a maize (Zea mays L.) field under two irrigation regimes and fertilized with sodium selenite.

Selenium (Se) is a trace element necessary for both human and livestock nutrition. To increase Se human intake, soil Se fertilizations were performed but the fate of the added Se remains unclear. The present research aims to: (1) determine the influence of Se fertilization on the fractionation of Se in soil; (2) assess the influence of water availability on the distribution of soil Se chemical fractions; and (3) monitor the Se content in soil, leachates and plants. To reach these goals, 200 g Se ha-1 was applied to soil as sodium selenite in maize crops under two irrigation regimes, and the Se content in plant, soil chemical fractions and leachates were analyzed. Se application increased the total Se content of the soil, specifically it increased the Se content of the soluble, exchangeable and organic fractions with more pronounced effect in the soils with higher water availability. These differences disappeared over time likely due to the Se loss through volatilization. The hypothesis of Se volatilization is confirmed by the absence of both leachates during the maize growing season and differences among the treatments of Se content in sub-soil samples. Also, although the Se treated plants showed higher Se content than the untreated ones, overall <1% of the added Se was assimilated by plants. Hence, this study demonstrated that the addition of selenite to the soil increased the Se contents of the plants, but the Se does not accumulate in the soil because it is likely lost via volatilization. Further, leaching of Se into groundwater is avoided due to its association with both the soil organic matter and positively charged binding sites of soil, and due to its loss via volatilization. Therefore, soil Se fertilization could increase the nutritional value of plants without consequences on the environment.

Ocular blood flow evaluation in injured and healthy fellow eyes.

PURPOSE: To assess if injured eyes develop ocular blood flow disturbances that may contribute to development of traumatic glaucoma. METHODS: Twenty-five eyes of 25 patients hospitalized from January 1997 to July 1999 for blunt (15) or penetrating (10) eye injury and elevated intraocular pressure (IOP) (>23 mm Hg) were controlled at least 24 months after the trauma and underwent visual field examination, pulsatile ocular blood flow (pOBF), and color Doppler imaging (CDI) analysis of ophthalmic artery, central retinal artery, nasal and temporal short posterior ciliary arteries. Uninjured healthy eye was used as control. RESULTS: IOP was significantly higher in injured eyes (15.1+/-3.3 vs 13.0+/-2.7 mmHg; p<0.01), but only 2 eyes (8%) were under medical treatment. pOBF values were significantly lower in injured eyes: 11.25+/-6.56 microL/sec in the trauma eyes and 15.40+/-7.29 in fellow eyes (p=0.002). Resistivity index of all investigated retrobulbar vessels was very significantly higher in injured eyes than in fellow eyes (p<0.0001). There is no significant correlation between IOP and ocular blood flow disturbance. CONCLUSIONS: Long-term follow-up (mean 39+/-12 months) of injured eyes shows, besides a slight but significant increase of IOP, a very significant impairment of ocular blood supply to injured eyes compared to healthy fellow eyes with reduction of pulsatile ocular blood flow and marked increase of resistance to flow in all retrobulbar vessels. These anomalies may be considered an independent risk factor to develop traumatic glaucoma.

Simple and reliable high-performance liquid chromatography fluorimetric procedure for the determination of amphetamine-derived designer drugs.

The paper describes a HPLC-fluorimetric procedure for the determination of methylenedioxyamphetamine, methylenedioxymethamphetamine, methylenedioxyethamphetamine and N-methyl-1-(1,3-benzodioxol-5-yl)-2-butanamine in urine, serum, saliva and street samples, that features interesting advantages over other procedures previously described. The method requires a very small sample volume (100 microl) and no extraction, lacks matrix effect, and is not time consuming. Linearity was in the range 50-1000 ng/ml regardless of matrix. Sensitivity and detection limit were 50 ng/ml and 10 ng/ml, respectively, but they may reach 10 ng/ml and 2 ng/ml if a slight modification is introduced in the procedure. Intra- and inter-day precision were always within 5% and 8%, respectively. Recovery was satisfactory for all matrices. The described procedure could be successfully used for clinical, epidemiological and forensic applications.

Fat body mass and pharmacokinetics of oral 6-mercaptopurine in children with acute lymphoblastic leukemia.

To evaluate the reasons for the wide variability in bioavailability of orally administered 6-mercaptopurine in children with acute lymphoblastic leukemia, we studied several pharmacokinetic parameters of the drug in 18 affected children receiving remission maintenance therapy, and compared them with their anthropometric data and with the results of intestinal function tests. No correlation was found between estimates of small intestinal absorption (the oral lactose tolerance test and 1 h blood xylose test) and 6-mercaptopurine serum levels. Of the anthropometric measurements considered, only the weight/height percentile (an index of the fat body mass) strongly and linearly correlated with the area under the curve of 6-mercaptopurine. The dose of 75 mg of 6-mercaptopurine/m2 of body surface resulted in higher serum concentrations in children below the 75th percentile than in those with a weight/height ratio exceeding the 75th percentile. In conclusion, these data caution about the risk of underdosing 6-mercaptopurine in overweight children when administering it on the basis of body surface area.