Effect of Different Selenium Supplementation Levels on Selenium Status in Camel

Twelve female camels divided into three groups received, after a 2-week adaptation period, an oral Se supplementation (0, 2, and 4 mg, respectively) under sodium selenite form for 3 months. Feed intake was assessed daily, blood samples and body weight were taken on a weekly basis, and feces and urine samples were collected every 2 weeks up to 1 month after the end of the supplementation period. The Se concentration in serum was increased significantly in supplemented groups. The maximum level was observed in the period of supplementation in the camel receiving 4 mg (492.5 ng/mL), which was fourfold higher than the value at the beginning of the trial (126 to 138.5 ng/mL according to the groups). The selenium concentration increased significantly in urine and feces but to a lesser extent. A similar trend was observed with glutathione-peroxidase (GSH-Px) values varying between 8.4 and 96.5 IU/g Hb. However, no difference occurred between the two groups receiving 2 or 4 mg Se at the supplementation period. Vitamin E (mean 1.13 +/- 0.61 microg/mL with range 0.27-3.09) did not change significantly. Significant correlations were reported between serum Se, GSH-Px, fecal, and urinary excretion or concentration.     

Effects of Selenium Supplementation on Antioxidant Defense and Glucose Homeostasis in Experimental Diabetes Mellitus

The objective of this study was to investigate the effects of different forms of Se supplementation on the antioxidant defense and glucose homeostasis in experimental diabetes. Sodium selenate (SS) or selenomethionine (SM) were administered (2 μmol Se kg⁻¹ day⁻¹) via orogastric route to streptozotocine (STZ)-induced diabetic rats in addition to basal diet for 12 weeks. Glucose levels in whole blood, glutathione peroxidase (GSH-Px) activity in erythrocytes, Se and fructosamine levels in plasma were evaluated monthly. Plasma Se levels increased significantly in all diabetic groups compared to basal measurements, being more prominent in SM group [p(SM₃/SM₀) = 0.018]. The increase in GSH-Px activities was significant at the end of the second month in SS [p(SS₂/SS₀) = 0.028], whereas at the end of the third month in SM the value was lower [p(SM₃/SM₀) = 0.018] and the unsupplemented diabetic control (DC) groups, p(DC₃/DC₀) = 0.012. Glucose increased significantly only in DC group. Fructosamine increased gradually in all diabetic groups, being significant in DC and SS groups. At the end of the third month, highest fructosamine levels were observed in SS group, which were significantly higher than the SM group [p(SM/SS) = 0.010]. In conclusion, Se augmented the antioxidant defense by increasing GSH-Px activity and this effect was more prominent when Se was supplemented as SM, which exerted positive effects also on glucose homeostasis.     

Prevention of Keshan Disease by Selenium Supplementation: a Systematic Review and Meta-analysis

The optimal content of macro-, micro-, and trace elements in tissues ensures proper systemic growth and development and optimal health status in animals and humans. However, very little is known on the elemental content in the plasma compartment in Silver fox. The aim of this study was to determine the content of selected elements in serum obtained from 8-month-old female (N?=?8) and male (N?=?7) silver foxes. Moreover, relationships of the evaluated elements with the morphological, densitometric, and mechanical parameters of the mandible were determined. Serum content of 12 different elements was measured using inductively coupled plasma-atomic emission spectrometry. The morphometric and densitometric properties of the mandible were determined using quantitative computed tomography method, while mechanical endurance was tested using a three-point bending test. Serum concentration of calcium was significantly higher by 20% in male foxes (P?=?0.01), while manganese concentration was significantly lower in males by over 17% (P?=?0.03). Positive correlations of serum concentration of calcium, phosphorus, and magnesium with the morphological traits of the mandible such as weight, length, and bone volume were stated (P?<?0.05). In the group of elements playing regulatory functions, the positive relationships between serum concentrations of selenium, chromium, manganese, copper, and cobalt were found (P?<?0.05). The elaborated experimental model may serve for further studies on foxes, especially focused on nutritional factors affecting elemental homeostasis, whole-body metabolism, and systemic growth and development. Daily diet formulation and precise delivery for farm foxes, together with relatively large animal population maintained at the same environmental conditions, regularly subjected to slaughter procedure, enable economical experimentation with various dietary and pharmacological manipulations.     

Zinc Supplementation Ameliorates Diabetic Cataract Through Modulation of Crystallin Proteins and Polyol Pathway in Experimental Rats

Biological Trace Element Research - Non-enzymatic glycation of lens proteins and elevated polyol pathway in the eye lens have been the characteristic features of a diabetic condition. We have...     

Sequential Pathology of Experimental Aflatoxicosis in Quail and the Effect of Selenium Supplementation in Modifying the Disease Process

Feeding of aflatoxin B1 @ 1 ppm to 2-week old Japanese quail for a period of 8 weeks produced gross and microscopic changes in the liver, skeletal muscles, heart and bursa of Fabricius. These included fatty changes, bile duct hyperplasia and lymphoid aggregation in liver; haemorrhages in thigh, breast muscles and myocardium; mild depletion of lymphocytes, cystic degeneration and fibrous tissue proliferation in bursa of Fabricius. More or less similar lesions were seen in quail chicks fed on aflatoxin with sodium selenite @ 5 ppm but these were of lesser intensity and appeared at later stages of the experiment thereby indicating that supplementation of selenium had some protective action against the toxic effect of aflatoxin B1 in Japanese quail.     

The Effect of Level and Source of Dietary Selenium Supplementation on Eggshell Quality

A 16-week-long experiment was performed to compare the effect of sodium selenite (SS) and selenium-enriched yeast (SY) supplementation on eggshell quality and also to evaluate breaking force correlation with other parameters of shell quality originating from hens fed with selenium supplementation. One hundred Shaver 579 hens (27 weeks old) with similar body size were randomly divided for five dietary treatments: basal diet without selenium supplementation and basal diets with two levels of selenium supplementation (0.4 or 0.8 mg/kg) via SS or SY. No adverse effect of Se inclusion in hen's feed, regardless of its source, on shell breaking force, shell deformation, shape index, shell thickness and shell percentage, were observed throughout the current study (P > 0.05). Moderate correlations were found between breaking force and nondestructive shell deformation for all diets (P < 0.05). There was no significant overall correlation between egg breaking force and shell thickness or/and percentage shell in the presence of selenium supplemention (P > 0.05). Shape index in all four selenium-supplemented groups was not related to the breaking force (P > 0.05). Selenium supplementation of up to 0.8 mg/kg, regardless of its source, in the diet of laying hens in their first phase of laying does not adversely affect eggshell quality.     

Impact of Maternal Selenium Supplementation from Late Gestation and Lactation on Piglet Immune Function

Biological Trace Element Research - The present work aimed at assessing passive, innate, and acquired immunity in piglets from sows supplemented with either organic or inorganic selenium (Se). A...     

Biochemical Modulation of NMDA Receptors: Role in Conditioned Taste Aversion

Glutamate neurotransmission plays a crucial role in a variety of functions in the central nervous system, including learning and memory. However, little is known about the mechanisms underlying this process in mammals because of the scarceness of experimental models that permit correlation of behavioral and biochemical changes occurring during the different stages of learning and the retrieval of the acquired information. One model that has been useful to study these mechanisms is conditioned taste aversion (CTA), a paradigm in which animals learn to avoid new tastes when they are associated with gastrointestinal malaise. Glutamate receptors of the N-methyl-D-aspartate (NMDA) type appear to be necessary in this process, because blockade of this receptor prevents CTA. Phosphorylation of the main subunits of the NMDA receptor is a well-established biochemical mechanism for the modulation of the receptor response. Such modulation seems to be involved in CTA, because inhibitors of protein kinase C (PKC) block CTA acquisition and because the exposure to an unfamiliar taste results in an increased phosphorylation of tyrosine and serine residues of the NR2B subunit of the receptor in the insular cortex, the cerebral region where gustatory and visceral information converge. In this work we review these mechanisms of NMDA receptor modulation in CTA.     

Effect of Organic Selenium Supplementation on Selenium Status,Oxidative Stress,and Antioxidant Status in Selenium-Adequate Dairy Cows During the Periparturient Period

The periparturient period represents a stressful time for dairy cows as they transition from late gestation to early lactation. Oxidation stress occurs during this period owing to the increased metabolic activity. Antioxidants supplementation slightly above the suggested requirements may be beneficial in relieving this kind of stress. The objective of this study was to determine whether supplementing selenium (Se) yeast to diets with adequate Se concentrations affects Se status, oxidative stress, and antioxidant status in dairy cows during the periparturient period. Twenty multiparous Holstein cows were randomly divided into two groups with ten replicates in each group. During the last 4 weeks before calving, cows were fed Se-yeast at 0 (control) or 0.3 mg Se/kg dry matter (Se-yeast supplementation), in addition to Na selenite at 0.3 mg Se/kg dry matter in their rations. The concentrations of Se, reactive oxygen species (ROS), hydrogen peroxide (H₂O₂), hydroxyl radical, malonaldehyde (MDA), α-tocopherol and glutathione (GSH), the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT), and the total antioxidant capacity (T-AOC) in plasma or erythrocyte of dairy cows were measured at 21 and 7 days prepartum, and at 7 and 21 days postpartum. Cows fed Se-yeast supplement during the last 4 weeks of gestation had higher plasma Se and lower MDA concentrations at 7 days prepartum, and at 7 and 21 days postpartum, and had higher whole blood Se and lower plasma ROS and H₂O₂ concentrations at 7 and 21 days postpartum compared with control cows. Se-yeast supplementation increased plasma and erythrocyte GSH-Px activities and erythrocyte GSH concentration at 7 days postpartum as compared to Se-adequate control cows. Compared with control cows, the enhanced SOD and CAT activities, increased α-tocopherol and GSH concentrations, and improved T-AOC in plasma at 7 and 21 days postpartum in Se-yeast-supplemented cows were also observed in this study. The results indicate that feeding Se-adequate cows a Se-yeast supplement during late gestation increases plasma Se status, improves antioxidant function, and relieves effectively oxidative stress occurred in early lactation.     

Postmortem Changes in Rat Brain: Studies on Membrane-Bound Enzymes and Receptors

The relationship between the stability of potential neurochemical markers and autolysis time was studied at 4 degrees C and 25 degrees C using postmortem brain samples from two rat strains. In general, qualitatively similar results were obtained with either N/Nih or Sprague-Dawley rats; however, quantitative differences were often observed, particularly in regard to benzodiazepine receptor changes. For every enzyme activity or binding property examined, no significant change was found when brains were kept at 4 degrees C for up to 72 h prior to freezing at -70 degrees C. Na,K-ATPase and low-affinity Ca-ATPase activities were also stable in brains kept at 25 degrees C for up to 72 h. Mg-ATPase activity was reduced in brains kept at 25 degrees C for 24 and 48 h. [3H]Guanidinoethylmercaptosuccinic acid [( 3H]GEMSA) binding to enkephalin convertase in the cytosol was not significantly changed in brains kept at 25 degrees C; however, a small increase was seen for [3H]GEMSA binding to the membrane fraction at 24, but not 48 and 72 h postmortem. [3H]Quinuclidinyl benzilate [( 3H]QNB) binding to muscarinic cholinergic receptors decreased in brains kept at 25 degrees C for 72 h. Opioid receptor binding also decreased in brains kept at 25 degrees C. Using [3H]2-D-alanine-5-D-leucine enkephalin to label delta opioid receptors, a statistically significant decrease in binding was observed as early as 6 h postmortem, and was completely abolished after 72 h at 25 degrees C. In contrast, [3H]naloxone binding was unchanged after 24 h at 25 degrees C, but was decreased after 48 and 72 h.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of Different Forms of Dietary Selenium Supplementation on Growth Performance,Meat Quality,Selenium Deposition,and Antioxidant Property in Broilers

This study was conducted to investigate the effects of different sources of dietary selenium (Se) supplementation on growth performance, meat quality, Se deposition, and antioxidant property in broilers. A total of 600 one-day-old Ross 308 broilers with an average body weight (BW) of 44.30 ± 0.49 g were randomly allotted to three treatments, each of which included five replicates of 40 birds. These three groups received the same basal diet containing 0.04 mg Se/kg, supplemented with 0.15 mg Se/kg from sodium selenite (SS) or from l-selenomethionine (l-Se-methionine (Met)) or from d-selenomethionine (d-Se-Met). The experiment lasted 42 days. Both Se source and time significantly influenced (p < 0.01) drip loss of breast muscle. Supplementation with l-Se-Met and d-Se-Met were more effective (p < 0.05) in decreasing drip loss than SS. Besides, the pH value of breast muscle was also significantly influenced (p < 0.05) by time. The SS-supplemented diet increased more (p < 0.05) liver, kidney, and pancreas glutathione peroxidase (GSH-Px) activities than the d-Se-Met-supplemented diet. In addition, l-Se-Met increased more (p < 0.01) liver and pancreas GSH-Px activities than d-Se-Met. The antioxidant status was greatly improved in broilers of l-Se-Met-treated group in comparison with the SS-treated group and was illuminated by the increased glutathione (GSH) concentration in serum, liver, and breast muscle (p < 0.05); superoxide dismutase (SOD) activity in liver (p < 0.01); total antioxidant capability (T-AOC) in kidney, pancreas, and breast muscle (p < 0.05) and decreased malondialdehyde (MDA) concentration in kidney and breast muscle (p < 0.05) of broilers. Besides, supplementation with d-Se-Met was more effective (p < 0.01) in increasing serum GSH concentration and decreasing breast muscle MDA concentration than SS. l-Selenomethionine supplementation significantly increased GSH concentration in liver and breast muscle (p < 0.05); SOD activity in liver (p < 0.01); and T-AOC in liver, pancreas, and breast muscle (p < 0.05) of broilers, compared with broilers fed d-Se-Met diet. The addition of l-Se-Met and d-Se-Met increased (p < 0.01) Se concentration in serum and different organs studied of broilers in comparision with broilers fed SS diet. Therefore, dietary l-Se-Met and d-Se-Met supplementation could improve antioxidant capability and Se deposition in serum and tissues and reduce drip loss of breast muscle in broilers compared with SS. Besides, l-Se-Met is more effective than d-Se-Met in improving antioxidant status in broilers.     

Minireview: Nicotinic Acetylcholine Receptors on Hippocampal Neurons: Distribution on the Neuronal Surface and Modulation of Receptor Activity

Abstract

The recent development of a technique that uses infrared microscopy for the visualization of well-defined areas on the surface of neurons, and a computerized system of micromanipulators led to the discovery that functional nicotinic acetylcholine receptors (nAChRs) are expressed at higher density on the dendrites than on the soma of rat hippocampal neurons. The finding that the expression of α-bungarotoxin-sensitive, α7-bearing, nAChRs and dihydro-β-erythroidine-sensitive,α4β2 nAChRs tends to increase along the dendritic length suggests that these receptors may be highly involved in the integration of synaptic functions in hippocampal neurons. The present report also discusses the finding that ligands such as the anticholinesterase galanthamine can modulate the nAChR activity by binding to a novel receptor site, and that 5-hydroxytryptamine (5-HT) may serve as an endogenous ligand for this site. The ability of 5-HT to modulate the nAChR function in vivo supports the concept that the overall CNS function is determined not only by the neuronal network established by the neuronal wiring, but also by a chemical network established by the ability of a single substance to act as the primary neurotransmitter in one system and as a co-transmitter in another system.     

Studies on the Bacteriophage 2 Receptors of Pseudomonas aeruginosa

The lysogenization of Pseudomonas aeruginosa strain BI with phage 2 resulted in the loss of the capacity to adsorb the same phage. The absence of phage 2 receptors on the surface of the lysogenized strain BI(2)(8) was confirmed by the failure of purified slime polysaccharide (SPB) or lipopolysaccharide (LPS) to inactivate phage 2. SPB and LPS from a phage 2-resistant strain also failed to inactivate phage 2 in contrast to the phage inactivation exhibited by the SPB and LPS obtained from the wild-type strain BI. Chemically, quantitative differences were apparent when the SPB and LPS of strains BI(2)(8) and BI/2S(2) were compared with those of the wild-type strain BI. The most striking difference noted was the absence of amino sugars in the SPB of strain BI/2S(2). The SPB of strain BI(2)(8) also contained a lower percentage of amino sugars compared with the SPB of the wild-type strain BI.     

The Effects of Probiotic Supplementation on Experimental Acute Pancreatitis: A Systematic Review and Meta-Analysis

Background

In February 2008, the results of the PRObiotics in PAncreatitis TRIAl (PROPATRIA) were published. This study investigated the use of probiotics in patients suffering from severe acute pancreatitis. No differences between the groups were found for any of the primary endpoints. However, mortality in the probiotics group was significantly higher than in the placebo group. This result was unexpected in light of the results of the animal studies referred to in the trial protocol. We used the methods of systematic review and meta-analysis to take a closer look at the relation between the animal studies on probiotics and pancreatitis and the PROPATRIA-trial, focussing on indications for harmful effects and efficacy.

Methods and results

Both PubMed and Embase were searched for original articles concerning the effects of probiotics in experimental acute pancreatitis, yielding thirteen studies that met the inclusion criteria. Data on mortality, bacterial translocation and histological damage to the pancreas were extracted, as well as study quality indicators. Meta-analysis of the four animal studies published before PROPATRIA showed that probiotic supplementation did not diminish mortality, reduced the overall histopathological score of the pancreas and reduced bacterial translocation to pancreas and mesenteric lymph nodes. Comparable results were found when all relevant studies published so far were taken into account.

Conclusions

A more thorough analysis of all relevant animal studies carried out before (and after) the publication of the study protocol of the PROPATRIA trial could not have predicted the harmful effects of probiotics found in the PROPATRIA-trial. Moreover, meta-analysis of the preclinical animal studies did show evidence for efficacy. It may be suggested, however, that the most appropriate animal experiments in relation to the design of the human trial have not yet been conducted, which compromises a fair comparison between the results of the animal studies and the PROPATRIA trial.     

Influence of Dietary Selenomethionine Supplementation on Performance and Selenium Status of Broiler Breeders and Their Subsequent Progeny

The study was conducted to investigate the effects of dietary maternal selenomethionine or sodium selenite supplementation on performance and selenium status of broiler breeders and their next generation. Two hundred and forty 39-week-old Lingnan yellow broiler breeders were allocated randomly into two treatments, each of which included three replicates of 40 birds. Pretreatment period was 2 weeks, and the experiment lasted 8 weeks. The groups were fed the same basal diet supplemented with 0.30 mg selenium/kg of sodium selenite or selenomethionine. After incubation, 180 chicks from the same parental treatment group were randomly divided into three replicates, with 60 birds per replicate. All the offspring were fed the same diet containing 0.04 mg selenium/kg, and the experiment also lasted 8 weeks. Birth rate was greater (p < 0.05) in hens fed with selenomethionine than that in hens fed with sodium selenite. The selenium concentration in serum, liver, kidney, and breast muscle of broiler breeders, selenium deposition in the yolk, and albumen and tissues' (liver, kidney, breast muscle) selenium concentrations of 1-day-old chicks were significantly (p < 0.01) increased by maternal selenomethionine supplementation compared with maternal sodium selenite supplementation. The antioxidant status of 1-day-old chicks was greatly improved by maternal selenomethionine intake in comparison with maternal sodium selenite intake and was evidenced by the increased glutathione peroxidase activity in breast muscle (p < 0.05), superoxide dismutase activity in breast muscle and kidney (p < 0.05), glutathione concentration in kidney (p < 0.01), total antioxidant capability in breast muscle and liver (p < 0.05), and decreased malondialdehyde concentration in liver and pancreas (p < 0.05) of 1-day-old chicks. Feed utilization was better (p < 0.05), and mortality was lower (p < 0.05) in the progeny from hens fed with selenomethionine throughout the 8-week growing period compared with those from hens fed with sodium selenite. In summary, we concluded that maternal selenomethionine supplementation increased birth rate and Se deposition in serum and tissues of broiler breeders as well as in egg yolk and egg albumen more than maternal sodium selenite supplementation. Furthermore, maternal selenomethionine intake was also superior to maternal sodium selenite intake in improving the tissues Se deposition and antioxidant status of 1-day-old chicks and increasing the performance of the progeny during 8 weeks of post-hatch life.     

Effect of Organic Selenium Supplementation on Growth, Se Uptake, and Nutrient Utilization in Guinea Pigs

Forty weaned male guinea pigs (Cavia porcellus) of 152.6?±?7.96 g mean body weight were divided into four equal groups and fed a common basal diet comprised of 25% ground cowpea (Vigna unguiculata) hay, 30% ground maize (Zea mays) grain, 22% ground gram (Cicer arietinum) grain, 9.5% deoiled rice (Oryza sativa) bran, 6% soybean (Glycine max) meal, 6% fish meal, 1.5% mineral mixture (without Se), and ascorbic acid at 200 mg/kg to meet their nutrient requirements along with 0, 0.1, 0.2, and 0.3 ppm of organic selenium (Se) in groups I, II, III, and IV, respectively. Experimental feeding lasted for a period of 10 weeks, during which, daily feed intake and weekly body weights were recorded. Intake and digestibility of dry matter, organic matter, ether extract, crude fiber, and nitrogen-free extract as well as uptake of calcium and phosphorus were similar (P?>?0.05) among the four groups. Feed:gain ratio was also similar (P?>?0.05) in the four groups. However, digestibility of crude protein was significantly (P?<?0.001) higher in group II supplemented with 0.1 ppm organic Se as compared to other three group. Intake and absorption of Se was significantly (P?<?0.001) higher in all the Se supplemented groups as compared to control group. Average daily gain (ADG) was significantly (P?<?0.05) higher in group II (3.16 g/day) and III (3.38 g/day) as compared to group I (2.88 g/day). However, ADG in group IV (supplemented 0.3 ppm organic Se) was significantly (P?<?0.05) lower (2.83 g/day) than group II and III, but comparable (P?>?0.05) to group I. Findings of the present experiment suggests that Se requirements of guinea pigs are ≥0.2 ppm, as supplementation of 0.1 ppm organic Se in the diet (having 0.1 ppm Se) not only enhanced their growth rate but also improved the protein utilization.     

NMDA Receptors in Rat Cerebellum and Forebrain: Subtle Differences in Pharmacology and Modulation

Abstract: Binding of [³H]glutamate, [³H]glycine, and the glutamate antagonist [³H]CGS-19755 to NMDA-type glutamate receptors was examined in homogenates of rat forebrain and cerebellum. Most glutamate agonists had a higher affinity at the [³H]glutamate binding site of cerebellar NMDA receptors as compared with forebrain, whereas all the glutamate antagonists examined showed the reverse relationship. The [³H]glycine binding site of forebrain and cerebellar NMDA receptors showed a similar pharmacology in both brain regions. In the cerebellum, however, [³H]glycine bound to a second site with a 10-fold lower affinity and with a pharmacology that resembled that of the glycine/strychnine chloride channel. [³H]Glutamate binding was not affected by glycine agonists or antagonists, nor was [³H]glycine binding affected by glutamate agonists in either forebrain or cerebellum. Both CGS-19755 and 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid, glutamate antagonists, reduced [³H]glycine binding in cerebellum, whereas only CGS-19755 was effective in forebrain. Glycine agonists and antagonists modulated [³H]CGS-19755 binding in forebrain and cerebellum to different extents in the two brain regions. From these studies we conclude that the cerebellar NMDA receptor has a different pattern of modulation at glutamate and glycine sites and that glycine may play a more important role in the control of NMDA function in the cerebellum as compared with forebrain.