Synthesis of highly luminescent mercaptosuccinic acid‐coated CdSe nanocrystals under atmospheric conditions

Here we report a facile one‐pot method for the preparation of high‐quality CdSe nanocrystals (NCs) in aqueous solution under an air atmosphere. Compared with the traditional use of NaHSe or H₂Se, the more stable sodium selenite is utilized as the Se source for preparing highly luminescent CdSe nanocrystals. By using mercaptosuccinic acid (MSA) as the capping agent and borate–citrate acid as the buffering solution, CdSe nanocrystals with high quantum yield (up to 70%) have been synthesized conveniently. The influence of different experimental parameters, such as the pH of the precursor solution, the molar ratio of Cd²⁺ to Na₂SeO₃ and Cd²⁺ to MSA on the CdSe nanocrystals, has been systematically investigated. The prepared CdSe NCs were spherical with a size of ~ 5 nm. Copyright © 2014 John Wiley & Sons, Ltd.     

Difference in Selenite Absorption Between High- and Low-Selenium Rice Cultivars and its Mechanism

Two rice cultivars, Xiushui 48 and S. Andrea, with significant difference in selenium (Se) concentrations in brown rice grains, were chosen to study the Se absorption and its mechanism in excised roots. The results showed that the high-selenium cultivar Xiushui 48 absorbed higher amounts of Na₂SeO₃ than low-selenium S. Andrea at different Se levels and treatment periods. It was found that Na₂SO₃ markedly inhibited Na₂SeO₃ absorption by the excised roots of both cultivars. This inhibition might be due to the competition for uptake on the fact that Na₂SO₃ might share a common uptake pathway with Na₂SeO₃. Treatment with ZnCl₂ significantly decreased Na₂SeO₃ absorption of both cultivars possibly by inhibiting the activity of cysteine synthase. It was therefore postulated that the difference in cysteine synthase activity might be one of the reasons which resulted in difference in selenite absorption possibly between the two cultivars. Both HgCl₂ and AgNO₃ treatments can inhibit selenite absorption by rice roots greatly. We propose that selenite enters rice roots through aquaporins as the form of H₂SeO₃.     

Accumulation and volatilization of different chemical species of selenium by plants

Selenium (Se) removal from polluted waters and soils is especially complicated and highly expensive. Phytoremediation has been suggested as a low-cost, efficient technology for Se removal. Plants remove Se by uptake and accumulation in their tissues, and by volatilization into the atmosphere as a harmless gas. Unraveling the mechanisms of Se uptake and volatilization in plants may lead to ways of increasing the efficiency of the phytoremediation process. The objectives of this study were: (i) to determine the effect of different Se forms in the root substrate on the capacity of some plant species to take up and volatilize Se; (ii) to determine the chemical species of Se in different plant parts after the plants were supplied with various forms of Se; and (iii) to determine the influence of increasing sulfate levels on plant uptake, translocation, and volatilization of different Se species. Plants of broccoli (Brassica oleracea var. botrytis L.), Indian mustard (Brassica juncea L.), sugarbeet (Beta vulgaris L.) and rice (Oryza sativa L.) were grown hydroponically in growth chambers and treated for 1 week with 20 μM Se as Na₂SeO₄, Na₂SeO₃ or L-selenomethionine (SeMeth) and increasing sulfate levels. The data show that shoots of SeO₄-supplied plants accumulated the greatest amount of Se, followed by those supplied with SeMeth then SeO₃. In roots, the highest Se concentrations were attained when SeMeth was supplied, followed by SeO₃, then SeO₄. The rate of Se volatilization by plants followed the same pattern as that of Se accumulation in roots, but the differences were greater. Speciation analysis (X-ray absorption spectroscopy) showed that most of the Se taken up by SeO₄-supplied plants remained unchanged, whereas plants supplied with SeO₃ or SeMeth contained only SeMeth-like species. Increasing the sulfate level from 0.25 mM to 10 mM inhibited SeO₃ and SeMeth uptake by 33% and 15–25%, respectively, as compared to an inhibition of 90% of SeO₄ uptake. Similar results were observed with regard to sulfate effects on volatilization. We conclude that reduction from SeO₄ to SeO₃ appears to be a rate-limiting step in the production of volatile Se compounds by plants. Inhibitory effects of sulfate on the uptake and volatilization of Se may be reduced substantially if Se is supplied as, or converted to, SeO₃ and/or SeMeth rather than SeO₄. Received: 27 February 1998 / Accepted: 30 March 1998     

Elements of margin of safety,toxicity and action of sodium selenite in a lipopolysaccharide rat model

ProjectBoth septic shock and sodium selenite (Na₂SeO₃) lead to multiple organ failure through oxidation. Na₂SeO₃ has direct oxidant effects above the nutritional level and indirect anti-oxidant properties.In a lipopolysaccharide (LPS) rat model we assessed margin of safety, toxicity and beneficial effect of pentahydrate Na₂SeO₃ (5H₂O·Na₂SeO₃) at oxidant doses.ProcedureIn a three-step study on 204 rats we: (i) observed toxic effects of Na₂SeO₃ injected intraperitoneously (IP) and determined its Minimum Dose Without Toxic effect (MDWT) 0.25–0.35 mg/kg selenium (Se) content; (ii) injected IP LPS at 70% lethal dose (LD) followed, or not, one hour later by IP Na₂SeO₃ at MDWT and (iii) by doses > MDWT. At 48 h, in survivors, we measured plasma creatinine, lactate, aspartate and alanine aminotransferase (AST, ALT), nitric oxide (NO) and Se concentrations.Results(i) Na₂SeO₃ alone did not increase NO and lactate. Encephalopathy appeared at 1 mg Se/kg. Creatinine increased at 1–1.75 mg Se/kg, AST, ALT at 3–4.5 mg Se/kg, and the minimum LD was 3 mg Se/kg. (ii) Mortality after LPS was 37/50 (74%, [62–86%]) vs. 20/30 (67%, [50–84%]) when followed by Na₂SeO₃ at MDWT (p = 0.483) with a decreased in NO (−31%, p = 0.038) a trend for lactate decrease (−19%, p = 0.068) and an increased Se in plasma of survivals. (iii) All rats died at doses ≥0.6 mg/kg (p < 0.001).ConclusionMechanisms of LPS and Na₂SeO₃ toxicity differ (i.e. NO, lactate). In septic shock 5H₂O·Na₂SeO₃ toxicity increased, margin of safety decrease, but IP administration of dose considered as oxidant of 5H₂O·Na₂SeO₃ showed beneficial effects.     

Formate Dehydrogenase of Clostridium thermoaceticum: Incorporation of Selenium-75, and the Effects of Selenite, Molybdate, and Tungstate on the Enzyme

The formation of the nicotinamide adenine dinucleotide phosphate-dependent formate dehydrogenase in Clostridium thermoaceticum is stimulated by the presence of molybdate and selenite in the growth medium. The highest formate dehydrogenase activity was obtained with 2.5 × 10⁻⁴ M Na₂MoO₄ and 5 × 10⁻⁵ Na₂SeO₃. Tungstate but not vanadate could replace molybdate and stimulate the formation of formate dehydrogenase. Tungstate stimulated activity more than molybdate, and in combination with molybdate the stimulation of formation of formate dehydrogenase was additive. Formate dehydrogenase was isolated from cells grown in the presence of Na₂⁷⁵SeO₂, and a correlation was observed between bound ⁷⁵Se and enzyme activity.     

Effects of Selenium Source and Level on Growth Performance, Tissue Selenium Concentrations, Antioxidation, and Immune Functions of Heat-Stressed Broilers

An experiment is conducted to investigate the effects of selenium (Se) source and level on growth performance, tissue Se concentrations, antioxidation, and immune functions of heat-stressed broilers from 22 to 42?days of age. A total of 210 22-day-old Arbor Acres commercial male chicks were assigned by body weight to one of seven treatments with six replicates of five birds each in a completely randomized design involving a 3?×?2 factorial arrangement plus one Se-unsupplemented basal diet control (containing 0.027?mg of Se/kg). The three Se sources were sodium selenite (Na₂SeO₃), Se yeast, and AMMS Se (Se protein), and the two supplemental Se levels were 0.15 or 0.30?mg Se/kg. All birds were reared under heat-stressed condition (33?±?1?°C during 0900?C1700?hours and 27?±?1?°C during 1900?C0700?hours with a relative humidity of 60?C80?%). The results showed that heat-stressed chicks fed Se-supplemented diets had higher (P?<?0.10) average daily feed intake, Se concentrations in liver and breast muscle, liver glutathione peroxidase (GSH-Px) activity, serum antibody titers against H5N1(Re-4 strain), H5N1(Re-5 strain) and lower (P?<?0.01) mortality compared with the control. Chicks fed the diets supplemented with 0.30?mg/kg of Se had higher (P?<?0.05) Se concentrations in liver and breast muscle, liver GSH-Px activity, and serum antibody titer against H5N1 (Re-4 strain) than those fed the diets supplemented with 0.15?mg/kg of Se. Broilers fed the diets supplemented with Se yeast had higher (P?<?0.001) Se concentrations in liver and breast muscle than those fed the diets supplemented with Na₂SeO₃ or AMMS Se. However, broilers fed the diets supplemented with AMMS Se had higher (P?<?0.05) serum antibody titers against H5N1 (Re-4 strain) and H5N1 (Re-5 strain) than those fed the diets supplemented with Na₂SeO₃. These results indicated that Se yeast was more effective than Na₂SeO₃ or AMMS Se in increasing tissue Se retention; however, AMMS Se was more effective than Na₂SeO₃ or Se yeast in improving immune functions of heat-stressed broilers.     

Metabolic Depression in Cunner (Tautogolabrus adspersus) Is Influenced by Ontogeny,and Enhances Thermal Tolerance

To examine the effect of ontogeny on metabolic depression in the cunner (Tautogolabrus adspersus), and to understand how ontogeny and the ability to metabolically depress influence this species'' upper thermal tolerance: 1) the metabolic rate of 9°C-acclimated cunner of three size classes [0.2–0.5 g, young of the year (YOY); 3–6 g, small; and 80–120 g, large (adult)] was measured during a 2°C per day decrease in temperature; and 2) the metabolic response of the same three size classes of cunner to an acute thermal challenge [2°C h⁻¹ from 10°C until Critical Thermal Maximum, CT_Max] was examined, and compared to that of the Atlantic cod (Gadus morhua). The onset-temperature for metabolic depression in cunner increased with body size, i.e. from 5°C in YOY cunner to 7°C in adults. In contrast, the extent of metabolic depression was ∼80% (Q₁₀ = ∼15) for YOY fish, ∼65% (Q₁₀ = ∼8) for small fish and ∼55% (Q₁₀ = ∼5) for adults, and this resulted in the metabolic scaling exponent (b) gradually increasing from 0.84 to 0.92 between 9°C to 1°C. All size classes of cunner had significantly (approximately 60%) lower routine metabolic rates at 10°C than Atlantic cod. However, there was no species'' difference in the temperature-induced maximum metabolic rate, and this resulted in factorial metabolic scope values that were more than two-fold greater for cunner, and CT_Max values that were 6–9°C higher (∼21 vs. 28°C). These results: 1) show that ontogeny influences the temperature of initiation and the extent of metabolic depression in cunner, but not O₂ consumption when in a hypometabolic state; and 2) suggest that the evolution of cold-induced metabolic depression in this northern wrasse species has not resulted in a trade-off with upper thermal tolerance, but instead, an enhancement of this species'' metabolic plasticity.     

Selective Irreversible Inhibition of Neuronal and Inducible Nitric-oxide Synthase in the Combined Presence of Hydrogen Sulfide and Nitric Oxide

Citrulline formation by both human neuronal nitric-oxide synthase (nNOS) and mouse macrophage inducible NOS was inhibited by the hydrogen sulfide (H₂S) donor Na₂S with IC₅₀ values of ∼2.4·10⁻⁵ and ∼7.9·10⁻⁵ m, respectively, whereas human endothelial NOS was hardly affected at all. Inhibition of nNOS was not affected by the concentrations of l-arginine (Arg), NADPH, FAD, FMN, tetrahydrobiopterin (BH4), and calmodulin, indicating that H₂S does not interfere with substrate or cofactor binding. The IC₅₀ decreased to ∼1.5·10⁻⁵ m at pH 6.0 and increased to ∼8.3·10⁻⁵ m at pH 8.0. Preincubation of concentrated nNOS with H₂S under turnover conditions decreased activity after dilution by ∼70%, suggesting irreversible inhibition. However, when calmodulin was omitted during preincubation, activity was not affected, suggesting that irreversible inhibition requires both H₂S and NO. Likewise, NADPH oxidation was inhibited with an IC₅₀ of ∼1.9·10⁻⁵ m in the presence of Arg and BH4 but exhibited much higher IC₅₀ values (∼1.0–6.1·10⁻⁴ m) when Arg and/or BH4 was omitted. Moreover, the relatively weak inhibition of nNOS by Na₂S in the absence of Arg and/or BH4 was markedly potentiated by the NO donor 1-(hydroxy-NNO-azoxy)-l-proline, disodium salt (IC₅₀ ∼ 1.3–2.0·10⁻⁵ m). These results suggest that nNOS and inducible NOS but not endothelial NOS are irreversibly inhibited by H₂S/NO at modest concentrations of H₂S in a reaction that may allow feedback inhibition of NO production under conditions of excessive NO/H₂S formation.     

Synthesis,Crystal Structure and Thermal Decomposition of the New Cadmium Selenite Chloride,Cd4(SeO3)2OCl2

A synthetic study in the Cd-Se-O-Cl system led to formation of the new oxochloride compound Cd₄(SeO₃)₂OCl₂ via solid state reactions. The compound crystallizes in the orthorhombic space group Fmmm with cell parameters a = 7.3610(3) Å, b = 15.4936(2) Å, c = 17.5603(3) Å, Z = 8, S = 0.969, F(000) = 2800, R = 0.0185, R_w = 0.0384. Single crystal X-ray data were collected at 293 K. The crystal structure can be considered as layered and the building units are distorted [Cd(1)O₆] octahedra, distorted [Cd(2)O₈] cubes, irregular [Cd(3)O₄Cl₂] polyhedra and SeO₃E trigonal pyramids. There are two crystallographically unique Cl atoms that both are half occupied. Thermogravimetric studies show that the compound starts to decompose at 500°C. The crystal structure of the new compound is closely related to the previously described compound Cd₄(SeO₃)₂Cl₄(H₂O).     

Long-Term Prognostic Value of Restitution Slope in Patients with Ischemic and Dilated Cardiomyopathies

Background

An action potential duration (APD) restitution curve with a steep slope ≥1 has been associated with increased susceptibility for malignant ventricular arrhythmias. We aimed to evaluate the “restitution hypothesis” and tested ventricular APD restitution slope as well as effective refractory period (ERP)/APD ratio for long-term prognostic value in patients with ischemic (ICM) or dilated cardiomyopathy (DCM).

Methodology/Principal Findings

Monophasic action potentials were recorded in patients with ICM (n = 32) and DCM (n = 42) undergoing routine programmed ventricular stimulation (PVS). Left ventricular ejection fraction was 32±7% and 28±9%, respectively. APD and ERP were measured at baseline stimulation (S₁) and upon introduction of one to three extrastimuli (S₂–S₄). ERP/APD ratios and the APD restitution curve were calculated and the maximum restitution slope was determined. After a mean follow-up of 6.1±3.0 years, the combined end-point of mortality and and/or implantable cardioverter-defibrillator shock was not predicted by restitution slope or ERP/APD ratios. Comparing S₂ vs. S₃ vs. S₄ extrastimuli for restitution slope (1.5±0.6 vs. 1.4±0.4 vs. 1.3±0.5; p = NS), additional extrastimuli did not lead to a steepening restitution slope. ERP/APD ratio decreased with additional extrastimuli (0.98±0.09 [S₁] vs. 0.97±0.10 [S₂] vs. 0.93±0.11 [S₃]; p = 0.03 S₁ vs. S₃). Positive PVS was strongly predictive of outcome (p = 0.006).

Conclusions/Significance

Neither ventricular APD restitution slope nor ERP/APD ratios predict outcome in patients with ICM or DCM.     

Apamin Does Not Inhibit Human Cardiac Na+ Current,L-type Ca2+ Current or Other Major K+ Currents

Background

Apamin is commonly used as a small-conductance Ca²⁺-activated K⁺ (SK) current inhibitor. However, the specificity of apamin in cardiac tissues remains unclear.

Objective

To test the hypothesis that apamin does not inhibit any major cardiac ion currents.

Methods

We studied human embryonic kidney (HEK) 293 cells that expressed human voltage-gated Na⁺, K⁺ and Ca²⁺ currents and isolated rabbit ventricular myocytes. Whole-cell patch clamp techniques were used to determine ionic current densities before and after apamin administration.

Results

Ca²⁺ currents (CACNA1c+CACNB2b) were not affected by apamin (500 nM) (data are presented as median [25^th percentile;75^th percentile] (from –16 [–20;–10] to –17 [–19;–13] pA/pF, P = NS), but were reduced by nifedipine to –1.6 [–3.2;–1.3] pA/pF (p = 0.008). Na⁺ currents (SCN5A) were not affected by apamin (from –261 [–282;–145] to –268 [–379;–132] pA/pF, P = NS), but were reduced by flecainide to –57 [–70;–47] pA/pF (p = 0.018). None of the major K⁺ currents (I _Ks, I _Kr, I _K1 and I _to) were inhibited by 500 nM of apamin (KCNQ1+KCNE1, from 28 [20]; [37] to 23 [18]; [32] pA/pF; KCNH2+KCNE2, from 28 [24]; [30] to 27 [24]; [29] pA/pF; KCNJ2, from –46 [–48;–40] to –46 [–51;–35] pA/pF; KCND3, from 608 [505;748] to 606 [454;684]). Apamin did not inhibit the I _Na or I _CaL in isolated rabbit ventricular myocytes (I _Na, from –67 [–75;–59] to –68 [–71;–59] pA/pF; I _CaL, from –16 [–17;–14] to –14 [–15;–13] pA/pF, P = NS for both).

Conclusions

Apamin does not inhibit human cardiac Na⁺ currents, L-type Ca²⁺ currents or other major K⁺ currents. These findings indicate that apamin is a specific SK current inhibitor in hearts as well as in other organs.     

The Effect of Selenite Ions on Growth and Selenium Accumulation in Spirulina platensis

Selenium accumulation and the growth of cyanobacterium Spirulina platensis (Nordst.) Geitl. were studied in a culture with sodium selenite-supplemented nutritional medium. Selenite concentrations below 20 mg/l did not inhibit the growth of S. platensis. The addition of 30 mg/l of this salt somewhat decreased the growth rate during the linear growth phase, induced the earlier suspension transition to the steady-state phase, and substantially lowered the highest optical density of the suspension. However, even at 170 mg/l Na₂SeO₃, the culture still demonstrated a capacity for growth. The content of selenium in the cells depended directly on its concentration in the medium, up to the lethal level. At high selenium concentrations (100–170 mg/l), S. platensis reduced Se(IV) up to Se(0). The latter was secreted onto the cell surface and into the cultural medium. The high concentrations of Na₂SeO₃ acidified the cytoplasmic pH as was measured by ³¹P-NMR spectroscopy. At the same time, the content of protein on a dry weight basis decreased and that of carbohydrates and lipids somewhat increased, just as was observed in S. platensis cells under other stress factors. In the presence of 20 mg/l Na₂SeO₃, the selenium content in the biomass increased by 20000 times as compared to that in the control cells, whereas the biochemical composition of biomass did not change. In this case, the selenium was incorporated almost completely in the protein fraction. The selenium concentration in this fraction increased more significantly when the sulfur content was lowered in the medium.     

Accuracy of Specific BIVA for the Assessment of Body Composition in the United States Population

Background

Bioelectrical impedance vector analysis (BIVA) is a technique for the assessment of hydration and nutritional status, used in the clinical practice. Specific BIVA is an analytical variant, recently proposed for the Italian elderly population, that adjusts bioelectrical values for body geometry.

Objective

Evaluating the accuracy of specific BIVA in the adult U.S. population, compared to the ‘classic’ BIVA procedure, using DXA as the reference technique, in order to obtain an interpretative model of body composition.

Design

A cross-sectional sample of 1590 adult individuals (836 men and 754 women, 21–49 years old) derived from the NHANES 2003–2004 was considered. Classic and specific BIVA were applied. The sensitivity and specificity in recognizing individuals below the 5^th and above the 95^th percentiles of percent fat (FM_DXA%) and extracellular/intracellular water (ECW/ICW) ratio were evaluated by receiver operating characteristic (ROC) curves. Classic and specific BIVA results were compared by a probit multiple-regression.

Results

Specific BIVA was significantly more accurate than classic BIVA in evaluating FM_DXA% (ROC areas: 0.84–0.92 and 0.49–0.61 respectively; p = 0.002). The evaluation of ECW/ICW was accurate (ROC areas between 0.83 and 0.96) and similarly performed by the two procedures (p = 0.829). The accuracy of specific BIVA was similar in the two sexes (p = 0.144) and in FM_DXA% and ECW/ICW (p = 0.869).

Conclusions

Specific BIVA showed to be an accurate technique. The tolerance ellipses of specific BIVA can be used for evaluating FM% and ECW/ICW in the U.S. adult population.     

Brain MRI CO2 Stress Testing: A Pilot Study in Patients with Concussion

Background

There is a real need for quantifiable neuro-imaging biomarkers in concussion. Here we outline a brain BOLD-MRI CO₂ stress test to assess the condition.

Methods

This study was approved by the REB at the University of Manitoba. A group of volunteers without prior concussion were compared to post-concussion syndrome (PCS) patients – both symptomatic and recovered asymptomatic. Five 3-minute periods of BOLD imaging at 3.0 T were studied – baseline 1 (BL1– at basal CO₂ tension), hypocapnia (CO₂ decreased ∼5 mmHg), BL2, hypercapnia (CO₂ increased ∼10 mmHg) and BL3. Data were processed using statistical parametric mapping (SPM) for 1^st level analysis to compare each subject’s response to the CO₂ stress at the p = 0.001 level. A 2^nd level analysis compared each PCS patient’s response to the mean response of the control subjects at the p = 0.05 level.

Results

We report on 5 control subjects, 8 symptomatic and 4 asymptomatic PCS patients. Both increased and decreased response to CO₂ was seen in all PCS patients in the 2^nd level analysis. The responses were quantified as reactive voxel counts: whole brain voxel counts (2.0±1.6%, p = 0.012 for symptomatic patients for CO₂ response < controls and 3.0±5.1%, p = 0.139 for CO₂ response > controls: 0.49±0.31%, p = 0.053 for asymptomatic patients for CO₂ response < controls and 4.4±6.8%, p = 0.281 for CO₂ response > controls).

Conclusions

Quantifiable alterations in regional cerebrovascular responsiveness are present in concussion patients during provocative CO₂ challenge and BOLD MRI and not in healthy controls. Future longitudinal studies must aim to clarify the relationship between CO₂ responsiveness and individual patient symptoms and outcomes.     

定向驯化对异养蛋白核小球藻硒的耐受性及富集能力的影响

硒(Se)是生物体必不可少的微量元素,硒缺乏会导致人产生克山病、大骨节病等疾病,缺硒也会给畜牧业带来巨大损失。目前的补硒产品存在硒含量和生物利用度低、安全性差等问题,而通过小球藻培养可获得生物利用度高、安全性好的有机硒,因此是非常有应用前景的补硒产品。首先,为了获得对硒的耐受性和富集能力更强的藻种,研究通过定向驯化的方式逐步提高培养基中Na₂SeO₃浓度来驯化蛋白核小球藻,并对驯化时间和驯化过程中Na₂SeO₃的浓度梯度进行了优化。结果表明,驯化后的藻种对硒的耐受性和富集能力明显提高。在5L发酵罐中,驯化后的藻株可以耐受40mg/L的Na₂SeO₃,胞内有机硒合成速率提高了175.6%。之后,在5L发酵罐中进一步优化了硒的补加方式,在异养培养过程中分批补料添加40mg/LNa₂SeO₃时,最终获得的蛋白核小球藻细胞干重达106.4g/L,有机硒含量为1227mg/kg,有机硒合成速率为1.36mg/(L·h)。研究结果与已有蛋白核小球藻异养富硒文献报道的最高细胞密度75g/L和最高有机硒含量560mg/kg相比分别提高了41.9%和119.1%。上述结果表明,通过定向驯化的方法,可大大提高蛋白核小球藻对硒的耐受性和富集能力。     

Effects of Sodium Selenite and Germination on the Sprouting of Chickpeas (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) and Its Content of Selenium,Formononetin and Biochanin A in the Sprouts

To improve the nutritional value of chickpea food, selenium (Se)-rich chickpea sprouts were produced by germination of chickpea seeds for 6 days at 28 centigrade in the presence of various concentrations of Na₂SeO₃ in germination solution. High concentrations of selenite were found to inhibit the growth of chickpea sprout and the biosynthesis of isoflavones formononetin and biochanin A. However, chickpea sprouts could tolerate up to ∼50 mg/L of Na₂SeO₃, under which condition the product chickpea sprouts contained a high Se content (2.14 μg/g dry weight) and a moderate high content of isoflavones (601.56 μg biochanin A/g dry weight and 578.11 μg formononetin/g dry weight). Se was incorporated in chickpea sprout in the form of selenomethionine. Thus, Se-enriched chickpea sprouts may serve as a convenient dietary source of Se and of isoflavones, including formononetin and biochanin A.     

Regulation of cellular glutathione peroxidase by different forms and concentrations of selenium in primary cultured bovine hepatocytes

The expression and activity of cellular glutathione peroxidase (GPx1) are regulated by selenium (Se). Generally speaking, organic forms of Se have less toxicity and greater bioavailability compared with inorganic forms. In this study, the effects of different forms and concentrations of Se on the regulation of mRNA level and activity of GPx1 in bovine hepatocytes were evaluated, and the optimal doses of different forms of Se that supported the full expression of GPx1 were determined. Primary cultured bovine hepatocyte monolayers derived from neonatal male Holstein calves (aged 1–2 days) were incubated for 24 h with 0 (control), 0.5, 1, 1.5, 2, 3, 4 or 5 μmol/L of Se from dl-selenomethionine (Se-Met), sodium selenite (Na₂SeO₃) or Kappa-selenocarrageenan (Se-Car). Compared with controls, a significantly lower level of release of lactic dehydrogenase (LDH) was observed at 0.5–5 μmol/L of Se-Met, 0.5–1 μmol/L of Na₂SeO₃ and 0.5 μmol/L of Se-Car, but significantly higher LDH release was observed at 2–5 μmol/L of Na₂SeO₃ and 3–5 μmol/L of Se-Car, and the response occurred in a dose-dependent manner. The intracellular content of reduced glutathione in all hepatocytes treated with Se was significantly lower than that of controls. Significant increases in GPx1 mRNA were obtained in all hepatocytes treated with Se, with maximal effects at 3 μmol/L of Se-Met, 1.5 μmol/L of Na₂SeO₃ and 2 μmol/L of Se-Car, respectively. Furthermore, 3 μmol/L of Se from Se-Met resulted in peak levels of GPx1 mRNA. After reaching a maximal level, higher Se supplementation led to a reduction of GPx1 mRNA. The activity of GPx1 showed similar patterns but of lower magnitude. We conclude that (a) the regulation of mRNA level and activity of GPx1 in primary cultured bovine hepatocytes by different forms of Se varies and (b) the optimal doses of Se to support the full expression of GPx1 in bovine hepatocytes when supplied as Se-Met, Na₂SeO₃ and Se-Car are 3, 1.5 and 2 μmol/L, respectively.     

Effect of selenium compounds on the damage induced by oxysterol on rat arterial walls

Wistar rats were fed Se-deficient (0.017±0.002 mg Se/kg) and Seadequate (0.32±0.045 Se mg/kg) diets for 12 mo and then were given 5 mg/kg of cholestane-3β,tα,6β-triol (3-triol), intravenously. Se compounds (Na₂SeO₃ and ebselen) were supplemented in different doses and times to the Se-deficient rats. Twenty-four hours after 3-triol infusion, the changes in ultrastructures of rat aorta were examined by scanning electron micrography (SEM) and transmission electron micrography (TEM). SEM examinations showed that 3-triol induced diffused injuries on arterial endothelial urfaces of long-term Se-deficient rat, and a large number of holes or craterlike defects were observed. TEM examinations further showed that 3-triol induced swelling, necrosis, and shedding of endothelial cells, which resulted in the destruction of endothelial integrity. Mean-while, smooth muscle cells proliferated and migrated toward intimae; the breakage of internal elastic lamina benefited the migration of smooth muscle cells. Supplemented with Na₂SeO₃ (40 μg/kg, 10 d per continuum) and ebselen (20 mg/kg), respectively, exhibited significant protection from damages induced by 3-triol. It seems that protecting mechanisms were different between Na₂SeO₃ and ebselen. The present investigation gave visual evidence that both injuries induced by cholesterol oxides and the Se nutritional status contributed to the development of atherosclerosis.     

Selenium-induced protection of photosynthesis activity in rape (<Emphasis Type="Italic">Brassica napus</Emphasis>) seedlings subjected to cadmium stress. Fluorescence and EPR measurements

Fluorescence and electron paramagnetic resonance measurements were used to study selenium influence on photosystem activity in rape seedlings affected by Cd stress. Water cultures containing Hoagland nutrients were supplemented with 400 μM of CdCl₂, 2 μM of Na₂SeO₄ and a mixture of both CdCl₂ and Na₂SeO₄. The seedlings were cultured till the first leaf reached about 1 cm in length. Cadmium-induced changes in the activity of both photosystems were partly diminished by Se presence in the nutrient medium. Electron microscopy photographs confirmed less degradation in chloroplasts of plants cultured on media containing Se. It is suggested that sucrose groups of starch, which is deposited in greater amounts in Cd-stressed plants, may act as traps for free radicals produced under those conditions.