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.     

Effects of Selenium Supplementation on Expression of Endothelin-1 and Its Receptors in Pulmonary Microvascular Endothelial Cells from Chick Embryos

The objective of this study was to evaluate the effects of supplemental selenium (Se) on expression of endothelin-1 (ET-1) and its receptors in cultured chick embryos pulmonary microvascular endothelial cells (PMVECs). To accomplish this, PMVECs were treated in Se-deficient or Se-supplement (12, 24, 50, 100?ng/ml) culture medium for 48?h. Low Se medium was achieved by reducing serum concentrations and the essential growth factors were added. After the incubation, the effects of supplemental Se on ET-1 and its receptors gene expression were assessed by quantitative real-time PCR (qRT-PCR). Compared with the control group, our results showed that among the different concentrations of Se supplement, the levels of ET-1 gene expression treated with both the moderate Se doses (24, 50?ng/ml, P?<?0.01, P?<?0.01, respectively) and the high doses (100?ng/ml, P?<?0.05) were noticeably decreased, the low-dose group (12?ng/ml), which showed no changes. Meanwhile, Se supplement (24, 50, 100?ng/ml) was found to be effective in reducing the expression levels of ETA (P?<?0.01, P?<?0.05, P?<?0.05, respectively) in cultured PMVECs grown in low Se medium. However, there were no significant changes (P?>?0.05) in ETB mRNA levels during the cell proliferation. These observations indicated that Se may play both direct and indirect role in the regulation of ET-1 and its receptors gene expression and their production in avian PMVECs. Se supplement decreases in ET-1 and ETA production in Se-deficient PMVECs may partly explain the mechanism of the protective effects of the Se on the cardiovascular system.     

孤啡肽受体对痛觉调控作用的研究进展

孤啡肽受体是继经典的mu阿片受体、kappa阿片受体和delta阿片受体之后发现的又一类新型阿片受体,不仅在结构上具有同上述阿片受体相类似的特征,而且可介导相同或相似的细胞内生物学反应.孤啡肽受体对痛觉反应具有独特的调控模式.一方面,在背根神经节以及脊髓水平,孤啡肽受体主要介导镇痛效应,并且在脊髓水平还与其他阿片受体有协同效应以增强镇痛效果.另一方面,在脊髓上水平,孤啡肽受体往往产生痛敏而拮抗了其他阿片受体的镇痛效应.此外孤啡肽受体对痛觉的调控在不同物种间也表现一定的差异性.这为进一步阐明内源性阿片系统的痛觉调控作用提供一定的理论依据.     

Effect of Selenium Yeast Supplementation on Naturally Acquired Parasitic Infection in Ewes

Gastrointestinal parasites cause substantial economic losses in pasture-based sheep production systems. Supranutritional organic selenium (Se) supplementation may be beneficial because it improves immune responses to pathogens. To evaluate the effect of Se-yeast supplementation on gastrointestinal parasite load, 30 ewes per treatment group were drenched weekly with no Se, 4.9 mg Se/week as Se yeast (maximum FDA-allowed concentration), or supranutritional concentrations of Se yeast (14.7 and 24.5 mg Se/week) starting early fall for 85 weeks. Fecal samples were collected at weeks 63, 66, 78, and 84 and counted for total trichostrongyle-type eggs and Haemonchus contortus eggs (in samples with ≥200 trichostrongyle eggs/g feces). During breeding season (fall), ewes were kept on pasture; ewes receiving 24.5 mg Se/week had lower fecal trichostrongyle egg counts (93?±?40 eggs/g feces) compared with ewes receiving no Se (537?±?257 eggs/g feces; P?=?0.007) or ewes receiving 4.9 mg Se/week as Se yeast (398?±?208 eggs/g feces; P?=?0.03). In winter, fecal trichostrongyle egg counts decreased, and group differences were not apparent. During lambing season (spring), ewes were kept in the barn and fecal trichostrongyle egg counts increased, although no group differences were observed. However, none of the ewes receiving supranutritional Se yeast, and with trichostrongyle egg counts ≥200 eggs/g of feces, but four of the ewes receiving lower Se dosages had H. contortus egg counts ≥1,000 eggs/g feces (P?=?0.04). Our results suggest that supranutritional Se-yeast supplementation may enhance resistance to naturally occurring H. contortus gastrointestinal parasitism in sheep.     

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...     

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.     

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.     

用酵母双杂交系统研究载脂蛋白AI(apoAI)和清道夫受体BI(SR-BI)间的相互作用

目的:利用酵母双杂交系统验证在胆固醇逆转运过程中起关键作用的大鼠载脂蛋白AI(apoAI)和清道夫受体BI-(SR-BI)间存在着相互作用,为初步筛选具有降脂活性组分提供1对新的靶点。方法:首先分别克隆了Wistar大鼠的apoAI和SR-BI基因的cDNA,并构建了酵母表达载体,利用共转化技术观察到apoAI和SR-BI间存在着相互作用,并在酵母交配实验中证实了这个结果。结果:经共转化后的实验组与阳性对照组可在SD/-Leu/-Trp/-His/-Ade/X-α-Gal平板上生长且菌斑呈蓝色,经测定α、β半乳糖苷酶活力可知酶活分别为8～12U和10～40U。酵母交配后的二倍体实验组、阳性对照组可在SD/-Leu/-Trp/-His/-Ade/X-α-Gal平板上生长且菌斑呈蓝色。结论:apoAI和SRBI间的确存在相互作用。     

Subcellular Compartmentation of Opioid Receptors: Modulation by Enkephalin and Alkaloids

Abstract: A subclone of NG108–15 neuroblastoma-glioma hybrid cells was used to study the intracellular distribution of opioid receptors. Subcellular organelles were separated on self-generating Percoll-sucrose gradients and the enzymes β-glucuronidase, galactosyltransferase, 5′-nucleotidase, and glucose-6-phosphatase were used as markers to localize the various structures. Analysis of the receptor distribution from untreated cells shows that the plasma membranes contained the highest receptor density, but a significant portion of the opioid binding sites was unevenly distributed between the lysosomes, microsomes, and Golgi elements. The enzyme markers indicated that appearance of opioid receptors in these intracellular structures does not result merely from contamination with plasma membranes. About 11% of the receptors appeared in a fraction lighter than plasma membranes. The antilysosomal agent chloroquine altered the intracellular compartmentation of the receptors, possibly by blocking their translocation in the cells. Leu-enkephalin induced time-dependent loss of receptors from all four intracellular compartments examined, but a kinetic analysis showed that the rate of receptor loss in these fractions was not identical. Thus, the percent of receptors appearing in the lysosomal fraction that could still bind [³H]-D-Ala²D-Leu⁵-enkephalin in vitro was increased on treatment with Leu-enkephalin. As an additional approach to follow the intracellular fate of the receptors, cells were labeled with [³H]diprenorphine, chased with various unlabeled opiates, and the distribution of ³H-ligand-receptors in the cells was monitored. Leu-enkephalin and etorphine altered the distribution of receptor-bound [³H]diprenorphine between the plasma membranes, lysosomes, and Golgi elements, whereas morphine had no such effect. The study sheds light on the role of intracellular structures in the metabolism of opioid receptors in untreated and opioid-treated cells.     

肉毒神经毒素受体的研究进展

肉毒神经毒素(botulinumneurotoxin)是世界已知毒性最强的生物毒素,它通过酶切在递质释放过程中起关键作用的SNARE蛋白,抑制神经递质释放,阻断突触传递.综述了有关肉毒受体研究的进展.这些研究表明,肉毒的结合位点有低亲和力的和高亲和力的两种.肉毒的结合过程分两步,它首先与细胞表面的神经节苷脂结合,形成低亲和力的聚合体,然后再与高亲和力的蛋白受体——synaptotagmin结合,形成牢固的三聚体结构,并由内吞进入细胞.这种解释肉毒结合过程的双受体学说得到了越来越多的支持,文中列举和评述了支持该学说的实验资料.     

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.     

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...     

Modulation of Receptors for Thyrotropin-Releasing Hormone by Benzodiazepines: Brain Regional Differences

The benzodiazepines (BZDs) chlordiazepoxide (CDE), diazepam (DZM), and flurazepam (FLM) inhibited receptor binding for thyrotropin-releasing hormone (TRH) with low micromolar potency. In contrast, numerous other categories of drugs were previously shown to be inactive. Scatchard analysis of competition data suggested that the BZDs reduced TRH receptor affinity, consistent with competitive inhibition. Receptors from amygdala, retina, and pituitary appeared more sensitive to inhibition by BZDs than those from hypothalamus, hippocampus, spinal cord, or cerebellum. The latter four regions also gave shallower inhibition curves. CDE revealed an apparently biphasic dissociation of [3-Me-His2]TRH([3H]MeTRH) from amygdala membranes at 4 degrees C, with kinetics similar to those with TRH. These results suggest that TRH receptors in the brain are heterogeneous and that certain BZDs in high therapeutic concentrations may exert central effects through actions at TRH receptors or coupled proteins.     

脱落酸（ABA） 受体的研究进展

植物激素脱落酸(ABA)在植物对逆境适应及种子发育过程中具有重要的生理功能。尽管ABA作用的分子机制还不清楚,ABA受体还未得到鉴定,但近年来对ABA结合蛋白的研究取得了可喜的进展,已在多种植物中证明存在与ABA有高亲和力的结合蛋白。ABA的识别到底发生在胞外还是胞内,近几年随着微注射技术的应用,也得到不少实验证据。ABA信号的转导途径,特别是位于下游区域参与信号传递的物质的研究取得重大进展,其中以ABA调节气孔保卫细胞开关的信号传递成为研究这一领域的模式体系。     

水分胁迫下自由基清除剂对番木瓜的生理保护效应

用维他命C(Vc)、维他命E(VE)和苯甲酸钠等作为外源自由基清除剂在水分胁迫前1d预处理番木瓜幼苗,研究其对番木瓜的生理保护效应。结果表明,3种外源自由基清除剂预处理有效地降低了水分胁迫下番木瓜叶片细胞质膜透性、POD活性、MDA和H2O2含量的上升程度,并能延缓叶片叶绿素和可溶性蛋白质含量和SOD活性的降低。外源自由基清除剂通过有效清除H2O2降低膜脂过氧化程度,从而减轻水分胁迫对番木瓜引起的自由基伤害和提高番木瓜的抗旱能力。不同自由基清除剂预处理对番木瓜的抗旱保护效果存在差异,其中以Vc预处理的保护效果最好。     

Effect of Dietary Selenium Supplementation on Growth and Reproduction of Silkworm Bombyx mori L.

Biological Trace Element Research - The effects of selenium (Se) on the growth and reproduction of the Lepidoptera insect, the silkworm, Bombyx mori L were investigated. Initially, the silkworms...     

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)