Molecular modeling and QSAR studies of a set of indole and benzimidazole derivatives as H<Subscript>4</Subscript> receptor antagonists

Histamine is an important biogenic amine, which acts with a group of four G-protein coupled receptors (GPCRs), namely H₁ to H₄ (H₁R – H₄R) receptors. The actions of histamine at H₄R are related to immunological and inflammatory processes, particularly in pathophysiology of asthma, and H₄R ligands having antagonistic properties could be helpful as antiinflammatory agents. In this work, molecular modeling and QSAR studies of a set of 30 compounds, indole and benzimidazole derivatives, as H₄R antagonists were performed. The QSAR models were built and optimized using a genetic algorithm function and partial least squares regression (WOLF 5.5 program). The best QSAR model constructed with training set (N = 25) presented the following statistical measures: r ² = 0.76, q ² = 0.62, LOF = 0.15, and LSE = 0.07, and was validated using the LNO and y-randomization techniques. Four of five compounds of test set were well predicted by the selected QSAR model, which presented an external prediction power of 80%. These findings can be quite useful to aid the designing of new anti-H₄ compounds with improved biological response.     

Dynamics of <Superscript>18</Superscript>O Incorporation from H <Subscript>2</Subscript><Superscript>18</Superscript>O into Soil Microbial DNA

Heavy water (H₂¹⁸O) has been used to label DNA of soil microorganisms in stable isotope probing experiments, yet no measurements have been reported for the ¹⁸O content of DNA from soil incubated with heavy water. Here we present the first measurements of atom% ¹⁸O for DNA extracted from soil incubated with the addition of H₂¹⁸O. Four experiments were conducted to test how the atom% ¹⁸O of DNA, extracted from Ponderosa Pine forest soil incubated with heavy water, was affected by the following variables: (1) time, (2) nutrients, (3) soil moisture, and (4) atom% ¹⁸O of added H₂O. In the time series experiment, the atom% ¹⁸O of DNA increased linearly (R ² = 0.994, p < 0.01) over the first 72 h of incubation. In the nutrient addition experiment, there was a positive correlation (R ² = 0.991, p = 0.006) between the log₁₀ of the amount of tryptic soy broth, a complex nutrient broth, added to soil and the log₁₀ of the atom% ¹⁸O of DNA. For the experiment where soil moisture was manipulated, the atom% ¹⁸O of DNA increased with higher soil moisture until soil moisture reached 30%, above which ¹⁸O enrichment of DNA declined as soils became more saturated. When the atom% ¹⁸O for H₂O added was varied, there was a positive linear relationship between the atom% ¹⁸O of the added water and the atom% ¹⁸O of the DNA. Results indicate that quantification of ¹⁸O incorporated into DNA from H₂¹⁸O has potential to be used as a proxy for microbial growth in soil.     

FTIR-spectral analysis of two photosynthetic H2-producing strains and their extracellular polymeric substances

The Fourier transform infrared (FTIR) spectra of the cells of two photosynthetic H₂-producing strains, Rhodoblastus acidophilus and Rhodobacter capsulatus, as well as their extracellular polymeric substances (EPS), were evaluated. The FTIR spectra of R. capsulatus and its EPS during its cultivation were also recorded. The main peaks in the spectra, including 1,080 cm⁻¹ (carbohydrates), 1,250 cm⁻¹ (nucleic acids), 2,830–2,930 cm⁻¹ (lipids), 1,660–1,535 cm⁻¹ (Amide I and II of proteins), were observed. The relative heights of these peaks in the spectra of the two strains were different, showing the difference in contents of various components in the cells or EPS. The ratios among the main components in the EPS obtained from the FTIR spectra were in good agreement with those from a conventional quantitative chemical analysis. As an easy, rapid, and direct technique, the FTIR spectroscopy could be used to characterize the components and their relative contents of EPS of photosynthetic bacteria.An erratum to this article can be found at     

Recent improvements in the development of A<Subscript>2B</Subscript> adenosine receptor agonists

Adenosine is known to exert most of its physiological functions by acting as local modulator at four receptor subtypes named A₁, A_2A, A_2B and A₃ (ARs). Principally as a result of the difficulty in identifying potent and selective agonists, the A_2B AR is the least extensively characterised of the adenosine receptors family. Despite these limitations, growing understanding of the physiological meaning of this target indicates promising therapeutic perspectives for specific ligands. As A_2B AR signalling seems to be associated with pre/postconditioning cardioprotective and anti-inflammatory mechanisms, selective agonists may represent a new therapeutic group for patients suffering from coronary artery disease. Herein we present an overview of the recent advancements in identifying potent and selective A_2B AR agonists reported in scientific and patent literature. These compounds can be classified into adenosine-like and nonadenosine ligands. Nucleoside-based agonists are the result of modifying adenosine by substitution at the N ⁶-, C²-positions of the purine heterocycle and/or at the 5′-position of the ribose moiety or combinations of these substitutions. Compounds 1-deoxy-1-{6-[N′-(furan-2-carbonyl)-hydrazino]-9H-purin-9-yl}-N-ethyl-β-D-ribofuranuronamide (19, hA₁ K _i = 1050 nM, hA_2A K _i = 1550 nM, hA_2B EC₅₀ = 82 nM, hA₃ K _i > 5 μM) and its 2-chloro analogue 23 (hA₁ K _i = 3500 nM, hA_2A K _i = 4950 nM, hA_2B EC₅₀ = 210 nM, hA₃ K _i > 5 μM) were confirmed to be potent and selective full agonists in a cyclic adenosine monophosphate (cAMP) functional assay in Chinese hamster ovary (CHO) cells expressing hA_2B AR. Nonribose ligands are represented by conveniently substituted dicarbonitrilepyridines, among which 2-[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]pyridin-2-ylsulfanyl]acetamide (BAY-60–6583, hA₁, hA_2A, hA₃ EC₅₀ > 10 μM; hA_2B EC₅₀ = 3 nM) is currently under preclinical-phase investigation for treating coronary artery disorders and atherosclerosis.     

Relationship between the extracellular polymeric substances and surface characteristics of Rhodopseudomonas acidophila

The relationship between the extracellular polymeric substances (EPS) and surface characteristics of Rhodopseudomonas acidophila in its different growth phases was established. The equilibrium constant of partition (K _par) and the Gibbs energies of partition (△G _par) between hexadecane and aqueous phases were also calculated according to the microbial adhesion to hexadecane (MATH) testing. The EPS content decreased with cultivation time at the logarithmic phase, but kept almost unchanged around 22.9 mg g⁻¹ dry cell at the stationary phase. The EPS production of R. acidophila had a significant effect on its surface characteristics. The relative hydrophobicity and the K _par values of R. acidophila before EPS extraction were both lower than those after extraction. Both EPS content and ratio of proteins to carbohydrates had a negative effect on the water contact angle of the bacterium, but had a positive influence on the bacterial surface free energy and its polar component. On the other hand, the EPS were not related with MATH% or the Gibbs energy of partition between hexadecane and aqueous phase.     

Kinetics of CO conversion into H<Subscript>2</Subscript> by <Emphasis Type="Italic">Carboxydothermus hydrogenoformans</Emphasis>

The objective of this study was to improve the biological water–gas shift reaction for producing hydrogen (H₂) by conversion of carbon monoxide (CO) using an anaerobic thermophilic pure strain, Carboxydothermus hydrogenoformans. Specific hydrogen production rates and yields were investigated at initial biomass densities varying from 5 to 20 mg volatile suspended solid (VSS) L⁻¹. Results showed that the gas–liquid mass transfer limits the CO conversion rate at high biomass concentrations. At 100-rpm agitation and at CO partial pressure of 1 atm, the optimal substrate/biomass ratio must exceed 5 mol CO g⁻¹ biomass VSS in order to avoid gas–liquid substrate transfer limitation. An average H₂ yield of 94 ± 3% and a specific hydrogen production rate of ca. 3 mol g⁻¹ VSS day⁻¹ were obtained at initial biomass densities between 5 and 8 mg VSS⁻¹. In addition, CO bioconversion kinetics was assessed at CO partial pressure from 0.16 to 2 atm, corresponding to a dissolved CO concentration at 70°C from 0.09 to 1.1 mM. Specific bioactivity was maximal at 3.5 mol CO g⁻¹ VSS day⁻¹ for a dissolved CO concentration of 0.55 mM in the culture. This optimal concentration is higher than with most other hydrogenogenic carboxydotrophic species.     

The insertion reactions of the p-complex silylenoid H<Subscript>2</Subscript>SiLiF with Si-X (X=F,Cl, Br,O, N) bonds

The insertion reactions of the silylenoid H₂SiLiF with SiH₃XH_n-1 (X = F, Cl, Br, O, N; n = 1, 1, 1, 2, 3) have been studied by DFT calculations. The results indicate that the insertions proceed in a concerted manner, forming H₃SiSiH₂XH_n-1 and LiF. The essence of H₂SiLiF insertion into Si-X bonds reactions are the donations of the electrons of X into the p orbital on the Si atom in H₂SiLiF and the σ electrons on the Si atom in H₂SiLiF to the positive SiH₃ group. The order of reactivity by H₂SiLiF insertion in vacuum indicates the reaction barriers decrease for the same-row element X from right to left and the same-family element X from up down in the periodic table. The insertion reactions in ether are similar to those in vacuum. The energy barriers in vacuum are higher than those in ether. The silylenoid insertions are thermodynamically exothermic both in vacuum and in ether.     

The emersion response of the Australian Yabby Cherax destructor to environmental hypoxia and the respiratory and metabolic responses to consequent air-breathing

The Australian Yabby Cherax destructor voluntarily emerges from water to breathe air with increased frequency as water PO₂ decreases. When the water PO₂ declined below 2.7 kPa the crayfish spent >50% of time breathing air. The respiratory gas transport, acid-base, ionic and energetic status were quantified in simulations of this emersion behaviour to determine the benefits that the crayfish may gain from switching to air-breathing. C. destructor initially showed an elevated O₂ uptake rate on emerging from hypoxic water, but after 1 h the O₂ uptake rate was not different from that of crayfish in normoxic water. During 3 h of air breathing, subsequent to 2.7 kPa aquatic hypoxia, the haemolymph PO₂ increased while oxygen content was essentially unchanged, although cardiac output increased 5-fold. The haemolymph PCO₂ increased from 0.44 to 1.21 kPa after 3 h while the CO₂ content increased from 3.47 to 8.66 mmol · l⁻¹ and the pH decreased from 7.73 to 7.57 after 1 h in air. In air C. destructor eventually achieved an O₂ uptake rate similar to that achieved in water. A general hyperglycaemia occurred without anaerobiosis. In air-breathing C. destructor, small changes in lactate appear to offset the decrease in haemocyanin-O₂ affinity caused by acid Bohr shift. During air-breathing, decreased haemocyanin-O₂ affinity assisted in maintaining O₂ diffusion into the tissues, but the ATP content of the tail muscle decreased so that after 3 h in air the energy charge was only 0.59. The data are consistent with a specific depression of the Emden-Meyerhof pathway, preventing either lactate formation or oxidative phosphorylation in the tail muscle, despite a concomitant glycogenolysis. Accepted: 26 February 1998     

Physicochemical characteristics of anaerobic H2-producing granular sludge

Granule-based biological H₂ production processes are gaining great popularity in recent years. An efficient and stable operating of such systems relies heavily on the performance of the H₂-producing granules (HPGs), which possess many unique properties compared with floc sludge and methanogenic granules. Hence, a full understanding of the sludge characteristics is essential. Especially, the physicochemical properties of HPGs may provide useful information for effective evaluation of system status. This review offers a systematical introduction of the physicochemical properties of HPGs, including size, morphology, settling velocity, permeability, rheology, surface charge, hydrophobicity and extracellular polymeric substances (EPS). We also analyze the relationships between these physicochemical factors and the system performance, and discuss the remaining challenges and future implications for sludge characterization and process monitoring. This work may facilitate a better understanding of granule-based biological H₂ production processes and offer a basis for timely process monitoring and manipulation.     

Effect of feed composition and upflow velocity on aggregate characteristics in anaerobic upflow reactors

Two upflow anaerobic hybrid reactors treated lactose and a mixture of ethanol, propionate and butyrate, respectively, at a volumetric loading rate of 3.7 kg chemical oxygen demand (COD) m⁻³day⁻¹, a hydraulic retention time of 5 days and a liquid upflow velocity of 0.01 m/h. Under steady-state conditions, the lactose-fed sludge had much higher (20%–100%) specific methanogenic conversion rates than the volatile-fatty acid␣(VFA)/ethanol-fed sludge for all substrates tested, including VFA. In both reactors, a flocculant sludge developed, although a much higher content of extracellular polysaccharide was measured in the lactose-fed sludge [1900 μg compared to 305 μg uronic acid/g volatile suspended solids (VSS)]. When the liquid upflow velocity of a third, VFA/ethanol-fed reactor was increased to 0.5 m/h, granulation of the sludge occurred, accompanied by a large increase (200%–500%) in the specific methanogenic conversion rates for the syntrophic and methanogenic substrates studied. Granulation reduced the susceptibility of the sludge to flotation. Glucose was degraded at a high rate (100 mg glucose gVSS⁻¹h⁻¹) by the sludge from the third reactor, despite not having been exposed to a sugar-containing influent for 563␣days. Received: 7 June 1996 / Received revision: 23 September 1996 / Accepted: 29 September 1996     

Ab initio studies on the decomposition kinetics of CF<Subscript>3</Subscript>OCF<Subscript>2</Subscript>O radical

The present study deals with the decomposition of CF₃OCF₂O radical formed from a hydrofluoroether, CF₃OCHF₂ (HFE-125), in the atmosphere. The study is performed using ab initio quantum mechanical methods. Two plausible pathways of decomposition of the titled species have been considered, one involving C-O bond scission and the other occurring via F atom elimination. The geometries of the reactant, products and transition states involved in the decomposition pathways are optimized and characterized at DFT (B3LYP) level of theory using 6-311G(d,p) basis set. Single point energy calculations have been performed at G2M(CC,MP2) level of theory. Out of the two prominent decomposition channels considered, the C-O bond scission is found to be dominant involving a barrier height of 15.3 kcal mol⁻¹ whereas the F-elimination path proceeds with a barrier of 26.1 kcal mol⁻¹. The thermal rate constants for the above two decomposition pathways are evaluated using canonical transition state theory (CTST) and these are found to be 1.78 × 10⁶ s⁻¹ and 2.83 × 10⁻⁷ s⁻¹ for C-O bond scission and F-elimination respectively at 298 K and 1 atm pressure. Transition states are searched on the potential energy surfaces involved during the decomposition channels and each of the transition states is characterized. The existence of transition states on the corresponding potential energy surface is ascertained by performing intrinsic reaction coordinate (IRC) calculation.     

Insights into ET<Subscript>A</Subscript> subtype selectivity of benzodiazepine endothelin receptor antagonists by 3D-QSAR approaches

ET_A subtype selective antagonists constitute a novel and potentially important class of agents for the treatment of pulmonary hypertension, heart failure, and other pathological conditions. In this paper, 60 benzodiazepine derivatives displaying potent activities against ET_A and ET_B subtypes of endothelin receptor were selected to establish the 3D-QSAR models using CoMFA and CoMSIA approaches. These models show excellent internal predictability and consistency, external validation using test-set 19 compounds yields a good predictive power for antagonistic potency. Statistical parameters of models were obtained with CoMFA-ET_A (q ² = 0.787, r ² = 0.935, r ² _pred  = 0.901), CoMFA-ET_B (q ² = 0.842, r ² = 0.984, r ² _pred  = 0.941), CoMSIA-ET_A (q ² = 0.762, r ² = 0.971, r ² _pred  = 0.958) and CoMSIA-ET_B (q ² = 0.771, r ² = 0.974, r ² _pred  = 0.953) respectively. Field contour maps (CoMFA and CoMSIA) corresponding to the ET_A and ET_B subtypes reflects the characteristic similarities and differences between these types. The results of this paper provide valuable information to facilitate structural modifications of the title compounds to increase the inhibitory potency and subtype selectivity of endothelin receptor.     

Influence of Selenium on Hepatic Mitochondrial Antioxidant Capacity in Ducklings Intoxicated with Aflatoxin B<Subscript>1</Subscript>

The aim of the study was to investigate the effect of selenium on hepatic mitochondrial antioxidant capacity in ducklings administrated with aflatoxin B₁ (AFB₁). Ninety 7-day-old ducklings were randomly divided into three groups (groups I–III). Group I was used as a blank control. Group II was administered with AFB₁ (0.1 mg/kg body weight). Group III was administered with AFB₁ (0.1 mg/kg body weight) plus selenium (sodium selenite, 1 mg/kg body weight). All treatments were given once daily for 21 days. The results showed that the activities of mitochondrial superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione reductase (GR) in group II ducklings significantly decreased when compared with group I (P < 0.01). Furthermore, the content of hepatic mitochondrial malondialdehyde (MDA) significantly increased (P < 0.01). However, the activities of hepatic mitochondrial SOD, CAT, GSH-Px, and GR in group III ducklings significantly increased when compared with group II (P < 0.05). In addition, the content of hepatic mitochondrial MDA significantly decreased (P < 0.01). These results revealed that AFB₁ significantly induced hepatic mitochondrial antioxidant dysfunction. However, sodium selenite could significantly ameliorate the negative effect induced by AFB₁.     

Kinetics and characteristics of 70 °C, VFA-grown, UASB granular sludge

We studied in batch reactors the kinetics and characterization of 70 °C, volatile fatty acids (VFAs)-grown, upflow anaerobic sludge blanket granular sludge with 55 and 35 °C sludge as reference. The half-saturation constant (K _s), the inhibition constant (K _i), the maximum specific methane production rate (μ_CH4max), and the inhibition response coefficient (n) of the 70 °C sludge were 6.15 mM, 48.2 mM, 0.132 h⁻¹, and 2.48, respectively, while no inhibition occurred at 55 and 35 °C, where the K _s was 3.67 and 3.82 mM, respectively. At 70 °C, the highest initial specific methanogenic activity (ISMA, 0.311 gCH₄-COD per gram volatile solids per day) on VFAs was about 12–15% lower than that on acetate and three to four times less than the ISMA for the 55 and 35 °C sludge. In the acetate conversion study, residual acetate (79 mg l⁻¹) at 70 °C was three to five times higher than that at 55 and 35 °C. Further, the methane produced as percentage of the acetate consumed at 70 °C (89%) was lower than that at 55 (95%) and 35 °C (97%). At 70 °C, 10% of the ISMA remained after 15 days of starvation as compared to 26% (55 °C) and 92% (35 °C) after 30 days of starvation. Thus, the kinetics of the 70 °C granular sludge seem to differ from those at 55 and 35 °C. Received: 1 February 1999 / Accepted: 20 March 1999     

Energetics of calling and metabolic substrate use during prolonged exercise in the European treefrog Hyla arborea

Rates of oxygen consumption and carbon dioxide release were measured in calling and resting European tree frogs using open-flow-through respirometry. The energetic cost of calling was high with an average of 1.076 ml O₂/(g · h) at average call rates of 8000 calls/h. The maximum factorial metabolic scopes averaged 24 with momentary peak values ranging between 5 and 41. There was a threefold difference in O₂-consumption between individual males calling at the same rate. Respiratory quotients indicated that both lipids and carbohydrates were used to fuel calling. Carbohydrates provided the major fuel (69% on average) with dependence on carbohydrates increasing with call rate. In contrast to marathon runners, there was no shift in metabolic substrate use over a calling period of 2–3 h. Accepted: 25 September 2000     

Microcalorimetric Study of <Emphasis Type="Italic">Tetrahymena</Emphasis> Growth Affected by Copper(II) Complexes

By means of microcalorimetry, the effect of four copper(II) complexes on Tetrahymena growth was investigated. The extent and duration of the inhibitory effect on the metabolism, judged by the rate constant, k, and the half inhibition concentration, IC₅₀, varied with the different complexes. The results showed that the half inhibition concentrations IC₅₀ of CuCl₂, (C₉H₆NO)₂Cu and [Cu(phen)₂]Cl₂⋅6H₂O were 9.9 × 10⁻⁴, 2.0 × 10⁻⁴, and 2.6 × 10⁻⁴ mol/L, respectively. The sequence of antibiotic activity of these three complexes was: (C₉H₆NO)₂Cu > [Cu(phen)₂]Cl₂⋅6H₂O > CuCl₂. The growth rate constants of [Cu(phen)₃]Cl₂⋅6H₂O did not change obviously with the increase of concentrations, but [Cu(phen)₃]Cl₂⋅6H₂O also can prolong the time of Tetrahymena growth.     

Insulin increases H<Subscript>2</Subscript>O<Subscript>2</Subscript>-induced pancreatic beta cell death

Insulin resistance results, in part, from impaired insulin signaling in insulin target tissues. Consequently, increased levels of insulin are necessary to control plasma glucose levels. The effects of elevated insulin levels on pancreatic beta (β) cell function, however, are unclear. In this study, we investigated the possibility that insulin may influence survival of pancreatic β cells. Studies were conducted on RINm, RINm5F and Min-6 pancreatic β-cells. Cell death was induced by treatment with H₂O₂, and was estimated by measurements of LDH levels, viability assay (Cell-Titer Blue), propidium iodide staining and FACS analysis, and mitochondrial membrane potential (JC-1). In addition, levels of cleaved caspase-3 and caspase activity were determined. Treatment with H₂O₂ increased cell death; this effect was increased by simultaneous treatment of cells with insulin. Insulin treatment alone caused a slight increase in cell death. Inhibition of caspase-3 reduced the effect of insulin to increase H₂O₂-induced cell death. Insulin increased ROS production by pancreatic β cells and increased the effect of H₂O₂. These effects were increased by inhibition of IR signaling, indicative of an effect independent of the IR cascade. We conclude that elevated levels of insulin may act to exacerbate cell death induced by H₂O₂ and, perhaps, other inducers of apoptosis.     

Effects of CO<Subscript>2</Subscript> inhalation exposure on mice vomeronasal epithelium

Nasal epitheliums are the first sites of the respiratory tract in contact with the external environment and may therefore be susceptible to damage from exposure to many toxic volatile substances (i.e., volatile organic components, vapors, and gases). In the field of inhalation toxicology, a number of studies have considered the main olfactory epithelium, but few have dealt with the epithelium of the vomeronasal organ (VNO). However, in several species such as in rodents, the VNO (an organ of pheromone detection) plays an important role in social interactions, and alterations of this organ are known to induce adaptative behavioral disturbances. Among volatile toxicants, health effects of inhaled gases have been thoroughly investigated, especially during CO₂ inhalation because of its increasing atmospheric concentration. Therefore, this work was designed to examine the effects of 3% CO₂ inhalation on VNO in two different exposure conditions (5 h/day and 12 h/day) in mice. Behavioral sensitivity tests to urine of congener and histological measurements of VNO were conducted before, during (weeks 1–4), and after (weeks 5–8) CO₂ inhalation exposures. Results showed no significant modifications of behavioral responses to urine, but there were significant changes of both cell number and thickness of the VNO epithelium. Moreover, the findings indicated a selectively dose-dependent effect of CO₂, and further research could use other gases in the same manner for comparison.     

Interaction Between Nanoparticulate Anatase TiO<Subscript>2</Subscript> and Lactate Dehydrogenase

In order to study the mechanisms underlying the effects of TiO₂ nanoparticles on lactate dehydrogenase (LDH, EC1.1.1.27), Institute of Cancer Research region mice were injected with nanoparticulate anatase TiO₂ (5 nm) of various doses into the abdominal cavity daily for 14 days. We then examined LDH activity in vivo and in vitro and direct evident for interaction between nanoparticulate anatase TiO₂ and LDH using spectral methods. The results showed that nanoparticulate anatase TiO₂ could significantly activate LDH in vivo and in vitro; the kinetics constant (Km) and Vmax were 0.006 μM and 1,149 unit mg⁻¹ protein min⁻¹, respectively, at a low concentration of nanoparticulate anatase TiO₂, and 3.45 and 0.031 μM and 221 unit mg⁻¹ protein min⁻¹, respectively, at a high concentration of nanoparticulate anatase TiO₂. By fluorescence spectral assays, the nanoparticulate anatase TiO₂ was determined to be directly bound to LDH, and the binding constants of the binding site were 1.77 × 10⁸ L mol⁻¹ and 2.15 × 10⁷ L mol⁻¹, respectively, and the binding distance between nanoparticulate anatase TiO₂ and the Trp residue of LDH was 4.18 nm, and nanoparticulate anatase TiO₂ induced the protein unfolding. It was concluded that the binding of nanoparticulate anatase TiO₂ altered LDH structure and function.     

Influence of Selenium on Body Weights and Immune Organ Indexes in Ducklings Intoxicated with Aflatoxin B<Subscript>1</Subscript>

To investigate the influence of selenium on body weights and the immune organ indexes in ducklings administrated with aflatoxin B₁ (AFB₁), 90 7-day-old ducklings were randomly divided into three groups (groups I–III). Group I was used as a blank control. Group II was administered with AFB₁ (0.1 mg/kg body weight). Group III was administered with AFB₁ (0.1 mg/kg body weight) plus sodium selenite (1 mg/kg body weight). All treatments were given once daily for 21 days. It showed that the ducklings’ bursa of fabricius, thymus indexes, and body weights in group II significantly decreased when compared with group I (P < 0.01). Furthermore, the spleen indexes significantly decreased (P < 0.01). However, the ducklings’ bursa of fabricius and thymus indexes, body weights in group III ducklings significantly increased when compared with group II (P < 0.01). In addition, the spleen indexes significantly decreased (P < 0.01). These results revealed that AFB₁ significantly affect ducklings’ growth and immune organs development. However, selenium significantly ameliorated the negative effects induced by AFB₁.