Skeletal muscle disorders associated with selenium deficiency in humans

Research progress on the biological regulatory mechanisms of selenium on skeletal muscle in broilers

As one of the indispensable trace elements for both humans and animals, selenium widely participates in multiple physiological processes and facilitates strong anti-inflammatory, antioxidant, and immune enhancing abilities. The biological functions of selenium are primarily driven by its presence in selenoproteins as a form of selenocysteine. Broilers are highly sensitive to selenium intake. Recent reports have demonstrated that selenium deficiency can adversely affect the quality of skeletal muscles and the economic value of broilers; the regulatory roles of several key selenoproteins (e.g., GPX1, GPX4, TXNRD1, TXNRD3, SelK, SelT, and SelW) have been identified. Starting from the selenium metabolism and its biological utilization in the skeletal muscle, the effect of the selenium antioxidant function on broiler meat quality is discussed in detail. The progress of research into the prevention of skeletal muscle injury by selenium and selenoproteins is also summarized. The findings emphasize the necessity of in vivo and in vitro research, and certain mechanism problems are identified, which aids their further examination. This mini-review will be helpful to provide a theoretical basis for the further study of regulatory mechanisms of selenium nutrition in edible poultry.

Possible relationship between the gut leaky syndrome and musculoskeletal injuries: the important role of gut microbiota as indirect modulator

This article aims to examine the evidence on the relationship between gut microbiota (GM), leaky gut syndrome and musculoskeletal injuries. Musculoskeletal injuries can significantly impair athletic performance, overall health, and quality of life. Emerging evidence suggests that the state of the gut microbiota and the functional intestinal permeability may contribute to injury recovery. Since 2007, a growing field of research has supported the idea that GM exerts an essential role maintaining intestinal homeostasis and organic and systemic health. Leaky gut syndrome is an acquired condition where the intestinal permeability is impaired, and different bacteria and/or toxins enter in the bloodstream, thereby promoting systemic endotoxemia and chronic low-grade inflammation. This systemic condition could indirectly contribute to increased local musculoskeletal inflammation and chronificate injuries and pain, thereby reducing recovery-time and limiting sport performance. Different strategies, including a healthy diet and the intake of pre/probiotics, may contribute to improving and/or restoring gut health, thereby modulating both systemically as local inflammation and pain. Here, we sought to identify critical factors and potential strategies that could positively improve gut microbiota and intestinal health, and reduce the risk of musculoskeletal injuries and its recovery-time and pain. In conclusion, recent evidences indicate that improving gut health has indirect consequences on the musculoskeletal tissue homeostasis and recovery through the direct modulation of systemic inflammation, the immune response and the nociceptive pain.

Shear wave imaging the active constitutive parameters of living muscles

Shear wave elastography (SWE) of human skeletal muscles allows for measurement of muscle elastic properties in vivo and has important applications in sports medicine and for the diagnosis and treatment of muscle-related diseases. Existing methods of SWE for skeletal muscles rely on the passive constitutive theory and have so far been unable to provide constitutive parameters describing muscle active behavior. In the present paper, we overcome this limitation by proposing a SWE method for quantitative inference of active constitutive parameters of skeletal muscles in vivo. To this end, we investigate the wave motion in a skeletal muscle described by a constitutive model in which muscle active behavior has been defined by an active parameter. An analytical solution relating shear wave velocities to both passive and active material parameters of muscles is derived, based upon which an inverse approach has been developed to evaluate these parameters. To demonstrate the usefulness of the reported method, in vivo experiments were carried out on 10 volunteers to obtain constitutive parameters, particularly those describing active deformation behaviors of living muscles. The results reveal that the active material parameter of skeletal muscles varies with warm-up, fatigue and rest. STATEMENT OF SIGNIFICANCE: Existing shear wave elastography methods are limited to imaging the passive parameters of muscles. This limitation is addressed in the present paper by developing a method to image the active constitutive parameter of living muscles using shear waves. We derived an analytical solution demonstrating the relationship between constitutive parameters of living muscles and shear waves. Relying on the analytical solution, we proposed an inverse method to infer active parameter of skeletal muscles. We performed in vivo experiments to demonstrate the usefulness of the theory and method; the quantitative variation of the active parameter with muscle states such as warm-up, fatigue and rest has been reported for the first time.

Advances in nutritional supplementation for sarcopenia management

Sarcopenia is a syndrome characterized by a decline in muscular mass, strength, and function with advancing age. The risk of falls, fragility, hospitalization, and death is considerably increased in the senior population due to sarcopenia. Although there is no conclusive evidence for drug treatment, resistance training has been unanimously recognized as a first-line treatment for managing sarcopenia, and numerous studies have also pointed to the combination of nutritional supplementation and resistance training as a more effective intervention to improve quality of life for people with sarcopenia. People with both malnutrition and sarcopenia have a higher mortality rate, so identifying people at risk of malnutrition and intervening early is extremely important to avoid sarcopenia and its associated problems. This article provides important information for dietary interventions in sarcopenia by summarizing the discoveries and developments of nutritional supplements such as protein, leucine, β-hydroxy-β-methylbutyric acid, vitamin D, vitamin C, vitamin E, omega-3 fatty acids, creatine, inorganic nitrate, probiotics, minerals, collagen peptides, and polyphenols in the management of sarcopenia.

Minerals and Sarcopenia in Older Adults: An Updated Systematic Review

OBJECTIVE

This systematic review aims to reevaluate the role of minerals on muscle mass, muscle strength, physical performance, and the prevalence of sarcopenia in community-dwelling and institutionalized older adults.

DESIGN

Systematic review.

SETTING AND PARTICIPANTS

In March 2022, a systematic search was performed in PubMed, Scopus, and Web of Sciences using predefined search terms. Original studies on dietary mineral intake or mineral serum blood concentrations on muscle mass, muscle strength, and physical performance or the prevalence of sarcopenia in older adults (average age ≥65 years) were included.

METHODS

Eligibility screening and data extraction was performed by 2 independent reviewers. Quality assessment was performed with the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies. Risk of bias was evaluated using the Risk Of Bias In Non-randomized Studies-of Exposure (ROBINS-E) tool.

RESULTS

From the 15,622 identified articles, a total of 45 studies were included in the review, mainly being cross-sectional and observational studies. Moderate quality of evidence showed that selenium (n = 8) and magnesium (n = 7) were significantly associated with muscle mass, strength, and physical performance as well as the prevalence of sarcopenia. For calcium and zinc, no association could be found. For potassium, iron, sodium, and phosphorus, the association with sarcopenic outcomes remains unclear as not enough studies could be included or were nonconclusive (low quality of evidence).

CONCLUSIONS AND IMPLICATIONS

This systematic review shows a potential role for selenium and magnesium on the prevention and treatment of sarcopenia in older adults. More randomized controlled trials are warranted to determine the impact of minerals on sarcopenia in older adults.

Serine Administration Improves Selenium Status, Oxidative Stress, and Mitochondrial Function in Longissimus Dorsi Muscle of Piglets with Intrauterine Growth Retardation

Intrauterine growth retardation (IUGR) causes oxidative stress in the skeletal muscle. Serine and selenoproteins are involved in anti-oxidative processes; however, whether IUGR affects selenium status and whether serine has beneficial effects remain elusive. Here, we investigated the effects of serine administration on selenium nutritional status and oxidative stress in the longissimus dorsi muscle of piglets with IUGR. Six newborn Min piglets having normal birth weight were administered saline, and 12 IUGR piglets were either administered saline or 0.8% serine. The results showed a lower selenium content in skeletal muscle in IUGR piglets, which was restored after serine administration. IUGR piglets showed a disturbed expression of genes encoding selenoproteins, with decreased expression of GPX2, GPX4, TXNRD1, and TXNRD3 and increased expression of DIO1, DIO2, SELF, SELM, SELP, and SELW. Notably, serine administration restored the expression levels of these genes. In accordance with the changes in gene expression, the activity of GPX, TXNRD, and DIO and the content of GSH and SELP were also altered, whereas serine administration restored their contents and activities. Moreover, we observed severe oxidative stress in the skeletal muscle of IUGR piglets, as indicated by decreased GSH content and increased MDA and PC content, whereas serine administration alleviated these changes. In conclusion, our results indicate that IUGR piglets showed a disturbed expression of genes encoding selenoproteins, accompanied by severe oxidative stress. Serine administration can improve selenium status, oxidative stress, and mitochondrial function in the longissimus dorsi muscle of piglets with IUGR. These results suggest that serine could potentially be used in the treatment of IUGR in piglets.

Selenium Content in Freshwater and Marine Fish from Southern Brazil Coastal Plain: a Comparative Analysis on Environmental and Dietary Aspects

The coastal plain of Rio Grande do Sul is considered to be a Se-deficient region in terms of its population dietary habit, making it the focus of this study. Selenium dietary deficiency is a concern when we consider its potential critical health effects on the local population. Therefore, this study contributes new information on the levels of Se in several species of marine and freshwater fish in the region of the Patos-Mirim Lagoon system, coupled with a comparative analysis of the metalloid contents between both fish groups. The Se contents in the fish species ranged from 88 ± 13 to 688 ± 19 μg.kg^-1. The average Se concentration in the muscle tissue of the freshwater species (251 ± 96 μg kg^-1) was significantly lower than that of the marine species (412 ± 143 μg kg^-1). Likewise, no evidence of Se biomagnification was found among the fish from both the marine and freshwater environments, suggesting the absence of trophic transfer of Se. We note that to ensure that the RDA (Recommended Daily Allowance, 55 μg day^-1) of Se dietary intake for adults is met, at least 134 g of freshwater or 82 g of marine fish fillet could be incorporated into the diet of the population of Rio Grande do Sul. According to target hazard quotients (THQ) and the permissible safety limits, consumption of the fish species analyzed is safe for human health.

MiR-129-3p regulates ferroptosis in the liver of Selenium-deficient broilers by targeting SLC7A11

Selenium (Se) has been proven to be an essential trace element for organism. Se deficiency in poultry can cause widespread damage, such as exudative diathesis. The liver is not only the main organ of metabolism, but also one of the organs with high Se content in organism. Recent studies have shown that solute carrier family 7 member 11 (SLC7A11) plays a key role in the negative regulation of ferroptosis. In order to explore the mechanism of Se deficiency induces liver ferroptosis in broilers, and the role of microRNAs (miRNAs) in this process, we divided broilers into 2 groups: control group (0.2 mg/kg Se) and Se deficiency group (0.03 mg/kg Se). Hematoxylin-Eosin staining detected liver tissue damage in broilers. Predicted and verified the targeting relationship between miR-129-3p and SLC7A11 through miRDB and dual luciferase report experiments. The genes related to ferroptosis were detected by qRT-PCR and Western Blot. The results showed that the expression level of miR-129-3p mRNA in Se-deficient liver was significantly increased. To understand whether the miR-129-3p/SLC7A11 axis could involve in the process of ferroptosis, our further research showed that overexpression of miR-129-3p could reduce the expression of SLC7A11 and its downstream GCL, GSS, and GPX4, thereby inducing ferroptosis. These data indicates that miR-129-3p affected ferroptosis under Se deficiency conditions through the SLC7A11 pathway. Our research provides a new perspective for the mechanism of Se deficiency on the liver damage.

Effects of Omega-3 and Antioxidant Cocktail Supplement on Prolonged Bed Rest: Results from Serum Proteome and Sphingolipids Analysis

Physical inactivity or prolonged bed rest (BR) induces muscle deconditioning in old and young subjects and can increase the cardiovascular disease risk (CVD) with dysregulation of the lipemic profile. Nutritional interventions, combining molecules such as polyphenols, vitamins and essential fatty acids, can influence some metabolic features associated with physical inactivity and decrease the reactive oxidative and nitrosative stress (RONS). The aim of this study was to detect circulating molecules correlated with BR in serum of healthy male subjects enrolled in a 60-day BR protocol to evaluate a nutritional intervention with an antioxidant cocktail as a disuse countermeasure (Toulouse COCKTAIL study). The serum proteome, sphingolipidome and nitrosoproteome were analyzed adopting different mass spectrometry-based approaches. Results in placebo-treated BR subjects indicated a marked decrease of proteins associated with high-density lipoproteins (HDL) involved in lipemic homeostasis not found in the cocktail-treated BR group. Moreover, long-chain ceramides decreased while sphingomyelin increased in the BR cocktail-treated group. In placebo, the ratio of S-nitrosylated/total protein increased for apolipoprotein D and several proteins were over-nitrosylated. In cocktail-treated BR subjects, the majority of protein showed a pattern of under-nitrosylation, except for ceruloplasmin and hemopexin, which were over-nitrosylated. Collectively, data indicate a positive effect of the cocktail in preserving lipemic and RONS homeostasis in extended disuse conditions.

Regulation of A-to-I RNA editing and stop codon recoding to control selenoprotein expression during skeletal myogenesis

Selenoprotein N (SELENON), a selenocysteine (Sec)-containing protein with high reductive activity, maintains redox homeostasis, thereby contributing to skeletal muscle differentiation and function. Loss-of-function mutations in SELENON cause severe neuromuscular disorders. In the early-to-middle stage of myoblast differentiation, SELENON maintains redox homeostasis and modulates endoplasmic reticulum (ER) Ca2+ concentration, resulting in a gradual reduction from the middle-to-late stages due to unknown mechanisms. The present study describes post-transcriptional mechanisms that regulate SELENON expression during myoblast differentiation. Part of an Alu element in the second intron of SELENON pre-mRNA is frequently exonized during splicing, resulting in an aberrant mRNA that is degraded by nonsense-mediated mRNA decay (NMD). In the middle stage of myoblast differentiation, ADAR1-mediated A-to-I RNA editing occurs in the U1 snRNA binding site at 5' splice site, preventing Alu exonization and producing mature mRNA. In the middle-to-late stage of myoblast differentiation, the level of Sec-charged tRNASec decreases due to downregulation of essential recoding factors for Sec insertion, thereby generating a premature termination codon in SELENON mRNA, which is targeted by NMD.

From the Bench to the Bedside: Branched Amino Acid and Micronutrient Strategies to Improve Mitochondrial Dysfunction Leading to Sarcopenia

With extended life expectancy, the older population is constantly increasing, and consequently, so too is the prevalence of age-related disorders. Sarcopenia, the pathological age-related loss of muscle mass and function; and malnutrition, the imbalance in nutrient intake and resultant energy production, are both commonly occurring conditions in old adults. Altered nutrition plays a crucial role in the onset of sarcopenia, and both these disorders are associated with detrimental consequences for patients (e.g., frailty, morbidity, and mortality) and society (e.g., healthcare costs). Importantly, sarcopenia and malnutrition also share critical molecular alterations, such as mitochondrial dysfunction, increased oxidative stress, and a chronic state of low grade and sterile inflammation, defined as inflammageing. Given the connection between malnutrition and sarcopenia, nutritional interventions capable of affecting mitochondrial health and correcting inflammageing are emerging as possible strategies to target sarcopenia. Here, we discuss mitochondrial dysfunction, oxidative stress, and inflammageing as key features leading to sarcopenia. Moreover, we examine the effects of some branched amino acids, omega-3 PUFA, and selected micronutrients on these pathways, and their potential role in modulating sarcopenia, warranting further clinical investigation.

The Relevance of Plant-Derived Se Compounds to Human Health in the SARS-CoV-2 (COVID-19) Pandemic Era

Dietary selenium (Se)-compounds accumulated in plants are essential for human metabolism and normal physiological processes. Inorganic and organic Se species can be readily absorbed by the human body, but are metabolized differently and thus exhibit distinct mechanisms of action. They can act as antioxidants or serve as a source of Se for the synthesis of selenoproteins. Selenocysteine, in particular, is incorporated at the catalytic center of these proteins through a specific insertion mechanism and, due to its electronic features, enhances their catalytic activity against biological oxidants. Selenite and other Se-organic compounds may also act as direct antioxidants in cells due to their strong nucleophilic properties. In addition, Se-amino acids are more easily subjected to oxidation than the corresponding thiols/thioethers and can bind redox-active metal ions. Adequate Se intake aids in preventing several metabolic disorders and affords protection against viral infections. At present, an epidemic caused by a novel coronavirus (SARS-CoV-2) threatens human health across several countries and impacts the global economy. Therefore, Se-supplementation could be a complementary treatment to vaccines and pharmacological drugs to reduce the viral load, mutation frequency, and enhance the immune system of populations with low Se intake in the diet.

Nutraceuticals in the Prevention and Treatment of the Muscle Atrophy

Imbalance of protein homeostasis, with excessive protein degradation compared with protein synthesis, leads to the development of muscle atrophy resulting in a decrease in muscle mass and consequent muscle weakness and disability. Potential triggers of muscle atrophy include inflammation, malnutrition, aging, cancer, and an unhealthy lifestyle such as sedentariness and high fat diet. Nutraceuticals with preventive and therapeutic effects against muscle atrophy have recently received increasing attention since they are potentially more suitable for long-term use. The implementation of nutraceutical intervention might aid in the development and design of precision medicine strategies to reduce the burden of muscle atrophy. In this review, we will summarize the current knowledge on the importance of nutraceuticals in the prevention of skeletal muscle mass loss and recovery of muscle function. We also highlight the cellular and molecular mechanisms of these nutraceuticals and their possible pharmacological use, which is of great importance for the prevention and treatment of muscle atrophy.

The lack of association between dietary antioxidant quality score with handgrip strength and handgrip endurance amongst Tehranian adults: A cross-sectional study from a Middle East country

OBJECTIVE

The association between dietary antioxidant quality score (DAQS) and handgrip strength (HS) and handgrip endurance (HE) is still unclear. We aimed to investigate whether adherence to dietary antioxidant quality score (DAQS) is associated with handgrip strength (HS) and handgrip endurance (HE) amongst adults in Tehran.

METHODS

This cross-sectional study was conducted on 270 (43.7% males, mean age 37 years and 56.3% females, mean age 35 years) apparently healthy adult subjects (53.2% were married) selected from different parts of Tehran, Iran. Dietary intake was assessed using a 168-item validated food frequency questionnaire. DAQS was calculated using antioxidant-nutrient intake. Body composition was measured using a body composition analyser. Handgrip strength and endurance were measured by a digital handgrip dynamometer. Relative muscle strength was expressed as the ratio of handgrip strength by body mass index (BMI).

RESULTS

The results showed that DAQs had no significant association with HS (P = .67, adjusted R²  = .60) and HE (P = .19, adjusted R²  = .08) after adjusting for potential confounders. However, a significant positive association was found between selenium intake and HE even after adjusting for potential confounders (P = .01, adjusted R²  = .10). After controlling for potential confounders no differences in the mean of HS (P = .29) and also HE (P = .61) amongst tertiles of DAQS was found. Positive linear association was found between vitamin C (P = .02, adjusted R²  = .53) and vitamin E (P = .03, adjusted R²  = .55) intake with relative muscle strength.

CONCLUSION

Our results revealed that no significant association between DAQS and HE and HS. It was found that more intake of selenium was positively linked to HE. Dietary intake of vitamin C and vitamin E are associated with higher relative muscle strength. It is evident that more prospective studies are needed to confirm the veracity of our results.

Nitrosative Redox Homeostasis and Antioxidant Response Defense in Disused Vastus lateralis Muscle in Long-Term Bedrest (Toulouse Cocktail Study)

Increased oxidative stress by reactive oxygen species (ROS) and reactive nitrogen species (RNS) is a major determinant of disuse-induced muscle atrophy. Muscle biopsies (thigh vastus lateralis, VL) obtained from healthy male subjects enrolled in the Toulouse Cocktail bedrest (BR) study were used to assess efficacy of an antioxidant cocktail (polyphenols, omega-3, vitamin E, and selenium) to counteract the increased redox homeostasis and enhance the antioxidant defense response by using label-free LC–MS/MS and NITRO-DIGE (nitrosated proteins), qPCR, and laser confocal microscopy. Label-free LC–MS/MS indicated that treatment prevented the redox homeostasis dysregulation and promoted structural remodeling (TPM3, MYH7, MYBPC, MYH1, MYL1, HRC, and LUM), increment of RyR1, myogenesis (CSRP3), and skeletal muscle development (MUSTN1, LMNA, AHNAK). These changes were absent in the Placebo group. Glycolysis, tricarboxylic acid cycle (TCA), oxidative phosphorylation, fatty acid beta-oxidation, and mitochondrial transmembrane transport were normalized in treated subjects. Proteins involved in protein folding were also normalized, whereas protein entailed in ion homeostasis decreased. NITRO-DIGE analysis showed significant protein nitrosylation changes for CAT, CA3, SDHA, and VDAC2 in Treatment vs. Placebo. Similarly, the nuclear factor erythroid 2-related factor 2 (Nrf-2) antioxidant response element (Nrf-2 ARE) signaling pathway showed an enhanced response in the Treatment group. Increased nitrosative redox homeostasis and decreased antioxidant defense response were found in post-BR control (Placebo, n = 10) vs. the antioxidant cocktail treated group (Treatment, n = 10). Taken together, increased nitrosative redox homeostasis and muscle deterioration during BR-driven physical inactivity were prevented, whereas decreased antioxidant nitrosative stress defense response was attenuated by Treatment suggesting positive effects of the nutritional intervention protocol in bedrest.

Dietary Selenium Intakes and Musculoskeletal Function in Very Old Adults: Analysis of the Newcastle 85+ Study

Background: Selenium is a trace element essential for health. Severe selenium deficiencies are associated with poor musculoskeletal (MSK) function. However, the effects of moderate deficiency on MSK function, especially in older adults, is unclear. Objectives: To determine the associations between selenium intake and MSK function in very old adults. Methods: Selenium intake at baseline and, hand-grip strength (HGS) and timed-up-and-go (TUG) at four phases over 5 years, were available in 791 participants in the Newcastle 85+ Study, a community-based, longitudinal cohort of ≥85 year old individuals. We investigated relationships between selenium intake and HGS and TUG in cross-sectional analyses at baseline using multivariate analyses and, prospectively using linear mixed models to explore HGS and TUG changes over 5 years in association with baseline selenium intake. Results: At baseline, 53% of participants had selenium intakes that were classified as low. These individuals had 2.80 kg lower HGS and were 2.30 s slower performing the TUG, cross-sectionally. In multivariate, baseline analyses, selenium intake had no significant impact on HGS or TUG. Selenium intake had no significant effect on MSK function, prospectively. Conclusion: Low selenium intake is common among very old adults and, in cross-sectional analyses, is associated with poorer MSK function.

Improved Calcium Homeostasis and Force by Selenium Treatment and Training in Aged Mouse Skeletal Muscle

During aging reduction in muscle mass (sarcopenia) and decrease in physical activity lead to partial loss of muscle force and increased fatigability. Deficiency in the essential trace element selenium might augment these symptoms as it can cause muscle pain, fatigue, and proximal weakness. Average voluntary daily running, maximal twitch and tetanic force, and calcium release from the sarcoplasmic reticulum (SR) decreased while reactive oxygen species (ROS) production associated with tetanic contractions increased in aged – 22-month-old – as compared to young – 4-month-old – mice. These changes were accompanied by a decline in the ryanodine receptor type 1 (RyR1) and Selenoprotein N content and the increased amount of a degraded RyR1. Both lifelong training and selenium supplementation, but not the presence of an increased muscle mass at young age, were able to compensate for the reduction in muscle force and SR calcium release with age. Selenium supplementation was also able to significantly enhance the Selenoprotein N levels in aged mice. Our results describe, for the first time, the beneficial effects of selenium supplementation on calcium release from the SR and muscle force in old age while point out that increased muscle mass does not improve physical performance with aging.

Effects of Dietary Selenium Deficiency or Excess on Selenoprotein Gene Expression in the Spleen Tissue of Pigs

To evaluate the effects of dietary Se deficiency and excess on the mRNA levels of selenoproteins in pig spleen tissues, 20 healthy uncastrated boars (Duroc × Landrace × Yorkshire, 10 ± 0.72 kg) were randomly divided into four groups (5 pigs per group). The pigs were fed a Se deficient corn-soybean basal feed (Se content <0.03 mg/kg) or basal feed with added sodium selenite at 0.3, 1.0, or 3.0 mg Se/kg diet, respectively. The experiment lasted 16 weeks. The spleen tissue was collected to examine the mRNA expression levels of 24 selenoprotein genes at the end of the study. Compared with pigs in other groups, those fed with the 1.0 mg Se/kg diet had higher mRNA levels of glutathione peroxidase 1 (Gpx1), glutathione peroxidase 2 (Gpx2), deiodinase type II (Dio2), thioredoxin reductase 3 (Txnrd3), selenoprotein H (Selh), selenoprotein N, 1 (Sepn1), selenoprotein P1 (Sepp1), and selenoprotein V (Selv) in the spleen (p < 0.05). Dietary Se deficiency resulted in lower mRNA levels of Gpx1, Gpx2, glutathione peroxidase 3 (Gpx3), Dio2, thioredoxin reductase 2 (Txnrd2), Txnrd3, Selh, selenoprotein I (Seli), selenoprotein K (Selk), selenoprotein M (Selm), Sepn1, Sepp1, and Selv in the spleen than the other three groups. Dietary Se levels did not affect the mRNA levels of glutathione peroxidase 4 (Gpx4), deiodinase type I (Dio1), deiodinase type III (Dio3), selenophosphate synthetase 2 (Sephs2), thioredoxin reductase 1 (Txnrd1), selenoprotein O (Selo), selenoprotein S (Sels), selenoprotein W (Selw), selenoprotein X (Selx), and selenoprotein 15 (Sel15) in the spleen (p > 0.05). Dietary Se levels can affect the transcription levels of 14 selenoprotein genes in the spleen of pigs.

Role of Selenoproteins in Bacterial Pathogenesis

The trace element selenium is an essential micronutrient that plays an important role in maintaining homeostasis of several tissues including the immune system of mammals. The vast majority of the biological functions of selenium are mediated via selenoproteins, proteins which incorporate the selenium-containing amino acid selenocysteine. Several bacterial infections of humans and animals are associated with decreased levels of selenium in the blood and an adjunct therapy with selenium often leads to favorable outcomes. Many pathogenic bacteria are also capable of synthesizing selenocysteine suggesting that selenoproteins may have a role in bacterial physiology. Interestingly, the composition of host microbiota is also regulated by dietary selenium levels. Therefore, bacterial pathogens, microbiome, and host immune cells may be competing for a limited supply of selenium. Elucidating how selenium, in particular selenoproteins, may regulate pathogen virulence, microbiome diversity, and host immune response during a bacterial infection is critical for clinical management of infectious diseases.

Insights on Nutrients as Analgesics in Chronic Pain

Many serious inflammatory disorders and nutrient deficiencies induce chronic pain, and anti-inflammatory diets have been applied successfully to modify the inflammatory symptoms causing chronic pain. Numerous scientific data and clinical investigations have demonstrated that long-term inflammation could lead to an inappropriate or exaggerated sensibility to pain. In addition, some Non-steroidal Anti-inflammatory Drugs (NSAID), which directly act on the many enzymes involved in pain and inflammation, including cyclooxygenases, are used to dampen the algesic signal to the central nervous system, reducing the responses of soft C-fibers to pain stimuli. On the other hand, there are a few reports from both health authorities and physicians, reporting that decreased transmission of pain signals can be achieved and improved, depending on the patient's dietary habit. Many nutrients, as well as a suitable level of exercise (resistance training), are the best methods for improving the total mitochondrial capacity in muscle cells, which can lead to a reduction in sensitivity to pain, particularly by lowering the inflammatory signaling to C-fibers. According to the current literature, it could be proposed that chronic pain results from the changed ratio of neuropeptides, hormones, and poor nutritional status, often related to an underlying inflammatory disorder. The current review also evaluates the effective role of nutrition-related interventions on the severity of chronic pain. This review pointed out that nutritional interventions can have a positive effect on pain experience through the indirect inhibitory effect on prostaglandin E2 and attenuation of mitochondrial dysfunction caused by ischemia/reperfusion in skeletal muscle, improving the intracellular antioxidant defense system. These data highlight the need for more nutrition studies where chronic pain is the primary outcome, using accurate interventions. To date, no nutritional recommendation for chronic pain has been officially proposed. Therefore, the goal of this article is to explore pain management and pain modulation, searching for a mode of nutrition efficient in reducing pain.

Detection of Se, Vit. E, Vit. A, MDA, 8-OHdG, and CoQ10 Levels and Histopathological Changes in Heart Tissue in Sheep with White Muscle Disease

This study was carried out to determine vit. E, Se, vit. A, malondialdehyde (MDA), 8-hydroxy-2-deoxyguanosine (8-OHdG), and ubiquinone-10 (CoQ10) levels and histopathological changes in sheep with white muscle disease (WMD). A total of 30 sheep were used; 20 sheep with WMD were brought to our clinic for diagnosis and treatment at various times, and 10 healthy sheep were in the control group. The Se, vit. E, vit. A, MDA, 8-OHdG, and CoQ10 values of the healthy and WMD sheep were as follows: 0.917 ± 0.037, 0.790 ± 0.067; 1.190 ± 0.011, 1.090 ± 0.021; 5.400 ± 0.275, 5.200 ± 0.173; 1.602 ± 0.264, 2.636 ± 0.576; 0.656 ± 0.197, 1.485 ± 0.271; and 0.280 ± 0.044, 1.753 ± 0.551 respectively (p < 0.05). According to histopathological and immunohistochemical findings in the WMD group, hyaline degeneration, Zenker's necrosis, and dystrophic calcification were observed in the muscle fibers. Immunohistochemically, 8-OHdG staining of the heart tissue determined a severe 8-OHdG expression in the WMD group. The findings of this study suggest that MDA, 8-OHdG, and CoQ10 values could be used as diagnostic and prognostic biomarkers in sheep affected with WMD.

Regulation and function of avian selenogenome

BACKGROUND

Selenium (Se) is an essential micronutrient required by avian species. Dietary Se/vitamin E deficiency induces three classical diseases in chicks: exudative diathesis, nutritional pancreatic atrophy, and nutritional muscular dystrophy.

SCOPE OF REVIEW

This review is to summarize and analyze the evolution, regulation, and function of avian selenogenome and selenoproteome and their relationship with the three classical Se/vitamin E deficiency diseases.

MAJOR CONCLUSIONS

There are 24 selenoproteins confirmed in chicks, with two avian-specific members (SELENOU and SELENOP2) and two missing mammalian members (GPX6 and SELENOV). There are two forms of SELENOP containing 1 or 13 selenocysteine residues. In addition, a Gallus gallus gene was conjectured to be the counterpart of the human SEPHS2. Expression of selenoprotein genes in the liver, pancreas, and muscle of chicks seemed to be highly responsive to dietary Se changes. Pathogeneses of the Se/vitamin E deficient diseases in the chicks were likely produced by missing functions of selected selenoproteins in regulating cellular and tissue redox balance and inhibiting oxidative/reductive stress-induced cell death.

GENERAL SIGNIFICANCE

Gene knockout models, similar to those of rodents, will help characterize the precise functions of avian selenoproteins and their comparisons with those of mammalian species.

Selenium deficiency in subtropical littoral pampas: environmental and dietary aspects

Se deficiency has a critical effect on human health. The littoral near Patos Lagoon in the south of Brazil is composed of Quaternary sandy deposits and nutrient-deficient soils, which contribute to Se deficiency in the surrounding environment. The average concentration of Se in littoral soils is six times lower than the metalloid deficiency threshold of 0.5 mg kg^-1 and is close to that in countries where Keshan disease is registered. The sediments in the Patos Estuary are also notably lower in Se than near-shore marine sediments. Foodstuffs produced in the littoral pampas are characterised by extremely low Se concentrations compared with the same alimentary products reported worldwide. The total daily dietary intake of Se in the region is 24 μg day^-1, which is half the Estimated Average Requirement for adults. Black beans in the local diet provide over 40% of daily Se intake. Prescriptive addition of Se to prevalent products seems the most effective solution to the problem of metalloid dietary deficiency in the region. Similar environmental conditions and significant concentration of the population in the littoral zone suggest that the problem of Se deficiency probably affects a large proportion of the population along the Atlantic coast of Brazil.

Pancreatic atrophy caused by dietary selenium deficiency induces hypoinsulinemic hyperglycemia via global down-regulation of selenoprotein encoding genes in broilers

This study was envisaged to comprehensively profile genes in selected tissues along with a few biochemical indicators and integrate resulting information with dietary selenium (Se) deficiency symptoms in broilers. A total of 120 one-day-old Cobb male broilers were equally divided into two groups and fed a Se deficient corn-soybean-based basal diet supplemented with 0.3 mg/kg sodium selenite (Control, Se adequate) or without selenite (Se deficiency) for five weeks. Effects of Se deficiency on mRNA abundance of twenty-three selenoprotein encoding genes and seventeen insulin signaling related genes were studied at day 35 in pancreas, liver and muscle along with plasma biochemical constituents and enzyme activities. Compared to healthy birds in control diet, Se deficient diet induced deficiency symptoms in 90% birds and classic nutritional pancreatic atrophy, depressed growth performance of broilers, and decreased (P < 0.01 to P < 0.05) total antioxidant capacity and activities of superoxide dismutase and glutathione peroxidase in plasma and three other tissues. Se deficiency resulted in 58% higher mortality than control birds. Dietary Se deficiency down-regulated (P < 0.01-0.05) eighteen selenoprotein encoding genes in pancreas, fourteen genes in muscle and nine genes in liver, and up-regulated (P < 0.05) Txnrd1 and Selx in liver. Meanwhile, six, thirteen and five insulin signaling related genes were down-regulated (P < 0.01-0.05) in pancreas, muscle and liver, respectively, and three genes were up-regulated (P < 0.01) in liver. The decrease (P < 0.05) in levels of plasma insulin, total triglyceride and total cholesterol, and concurrent elevated (P < 0.05) levels of plasma glucose and inflammatory cytokines accompanied the global down-regulation of selenoprotein encoding- and insulin signaling related- genes in Se deficient birds. It was concluded that dietary Se deficiency induces nutritional pancreatic atrophy and metabolic disorder of glucose and lipid in broilers via down-regulation of selenoprotein encoding- and insulin signaling related- genes, indicating potential roles of these genes in metabolic regulation.

Severe Selenium Deficiency Secondary to Chylous Loss

Selenium deficiency is observed in patients with poor intake. We report the first case of a child with lymphangiomatosis who presented a myopathy associated with severe cardiomyopathy secondary to selenium deficiency due to selenium loss in chylous fluid.

Dietary selenium augments sarcoplasmic calcium release and mechanical performance in mice

Background

As an essential trace element selenium plays a significant role in many physiological functions of the organs. It is found within muscles as selenocystein in selenoprotein N, which is involved in redox-modulated calcium homeostasis and in protection against oxidative stress.

Methods

The effects of two different selenium compounds (selenate and NanoSe in 0.5 and 5 ppm concentration for two weeks) on muscle properties of mice were examined by measuring in vivo muscle performance, in vitro force in soleus (SOL) and extensor digitorum longus (EDL) muscles and changes in intracellular Ca²⁺ concentration in single fibers from flexor digitorum brevis (FDB) muscle.. Western-blot analysis on muscle lysates of EDL and SOL were used to measure the selenoprotein N expression. Control mice received 0.3 ppm Se.

Results

While the grip force did not change, 5 ppm selenium diets significantly increased the speed of voluntary running and the daily distance covered. Both forms of selenium increased significantly the amplitude of single twitches in EDL and SOL muscle in a concentration dependent manner. Selenate increased fatigue resistance in SOL. The amplitude of the calcium transients evoked by KCl depolarization increased significantly from the control of 343 ± 44 nM to 671 ± 51 nM in the presence of 0.5 ppm selenate in FDB fibers. In parallel, the rate of calcium release during short depolarizations increased significantly from 28.4 ± 2.2 to 45.5 ± 3.8 and 52.1 ± 1.9 μM/ms in the presence of 0.5 ppm NanoSe and selenate, respectively. In 0.5 ppm concentration both selenium compounds increased significantly the selenoprotein N expression only in EDL muscle.

Conclusions

Selenium supplementation augments calcium release from the sarcoplasmic reticulum thus improves skeletal muscle performance. These effects are accompanied by the increased selenoprotein N expression in the muscles which could result in increased oxidative stress tolerance in case of long lasting contraction.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0134-6) contains supplementary material, which is available to authorized users.

Effect of Different Selenium Supplementation Levels on Oxidative Stress, Cytokines, and Immunotoxicity in Chicken Thymus

This study assessed the effects of different selenium (Se) supplementation levels on oxidative stress, cytokines, and immunotoxicity in chicken thymus. A total of 180 laying hens (1 day old; Mianyang, China) were randomly divided into 4 groups (n = 45). The chickens were maintained either on a basic diet (control group) containing 0.2 mg/kg Se, a low-supplemented diet containing 5 mg/kg Se, a medium-supplemented diet containing 10 mg/kg Se, or a high-supplemented diet containing 15 mg/kg Se for 15, 30, and 45 days, respectively. Over the entire experimental period, serum and thymus samples were collected and used for the detection of the experimental index. The results indicated that the antioxidative enzyme activities and messenger RNA (mRNA) levels of antioxidative enzymes, IFN-γ and IL-2 in the thymus, and the content of IFN-γ and IL-2 in the serum of excessive-Se-treated chickens at all time points (except for the 5 mg/kg Se supplement group at 15 days) were significantly decreased (P < 0.05) compared to the corresponding control groups. Interestingly, a significantly increase (P < 0.05) in the content of IFN-γ was observed in the serum and thymus in the 5 mg/kg Se supplement group at 15 and 30 days compared to the corresponding control groups. In histopathological examination, the thymus tissue from excessive-Se-treated chickens revealed different degrees of cortex drop, incrassation of the medulla, and degeneration of the reticular cells. These results suggested that the excessive Se could result in a decrease in immunity, an increase in oxidative damage, and a series of clinical pathology changes, such as cortex drop, incrassation of the medulla, and degeneration of the reticular cells.

Effects of Dietary Selenium Against Lead Toxicity on mRNA Levels of 25 Selenoprotein Genes in the Cartilage Tissue of Broiler Chicken

The interactions between the essential element selenium (Se) and the toxic element lead (Pb) have been reported extensively; however, little is known about the effect of Se on Pb toxicity and the expression pattern of selenoproteins in the cartilage of chicken. To investigate the effects of Se on Pb toxicity and the messenger RNA (mRNA) expressions of selenoproteins in cartilage tissue, an in vitro study was performed on 1-day-old broiler chickens (randomly allocated into four groups) with diet of different concentration of Se and Pb. After 90 days, the meniscus cartilage and sword cartilage tissue were examined for the mRNA levels of 25 selenoprotein genes. The results showed that Se and Pb influenced the expression of selenoprotein genes in the chicken cartilage tissue. In detail, Se could alleviate the downtrend of the expression of Gpx1, Gpx2, Gpx4, Txnrd2, Txnrd3, Dio1, Dio2, Seli, Selu, Sepx1, Selk, Selw, Selo, Selm, Sep15, Sepnn1, Sels, and Selt induced by Pb exposure in the meniscus cartilage. In the sword cartilage, Se alleviated the downtrend of the expression of Gpx2, Gpx3, Gpx4, Txnrd1, Txnrd2, Dio2, Dio3, Seli, Selh, SPS2, Sepx1, Selk, Selw, Selo, Selm, Sep15, Selpb, Sepn1, and Selt induced by Pb exposure. The present study provided some compensated data about the roles of Se against Pb toxicity in the regulation of selenoprotein expression.

Effect of Dietary Selenium Deficiency on the Cell Apoptosis and the Level of Thyroid Hormones in Chicken

This study assessed the effect of dietary selenium (Se) deficiency on male reproductive function in chicken. A total of 180 Hy-line laying cocks (1 day old; Weiwei) were randomly divided into 2 groups (n = 90) of Se-deficient chickens and control chickens. The control group was fed a basic diet (containing 0.15 mg of Se/kg). The Se-deficient group was fed a Se-deficient corn-soy basal diet (containing 0.033 mg of Se/kg). Fifteen chickens were killed in each group on days 30, 60, and 90, respectively. Then, serum and testes were collected and used in the detection of experimental index. Results indicated that GSH-Px activity and Bcl-2 mRNA level in the testes and thyroidal triiodothyronine (T3) and free triiodothyronine (FT3) levels in serum by dietary Se deficiency were significantly decreased compared to the corresponding control groups. Se deficiency-treated group showed a significant increase in MDA concent, TUNEL-positive cells, and mRNA level of Bax, Caspase3, and p53 in the testes and thyroidal thyroxine (T4), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) levels in serum. Histopathologically, Se deficiency caused impairments in the testes. These results suggested that dietary Se deficiency exerts significant harmful effects on male reproductive organ and that the intrinsic and extrinsic pathways and the upstream regulators such as p53, Bax, and Bcl-2 were all involved in Se deficiency-induced testicular apoptosis.

Selenoprotein W was Correlated with the Protective Effect of Selenium on Chicken Myocardial Cells from Oxidative Damage

Selenium (Se) mainly performs its function through Se-containing proteins. Selenoprotein W (SelW), one member of the selenoprotein family, plays important roles in the normal function of the heart. To investigate the possible relationship between Se and SelW for the regulation of oxidative damage in chicken embryo myocardial cells, we treated myocardial cells with Se and H2O2. Then, the levels of lactate dehydrogenase (LDH) and 3,4-methylenedioxyamphetamine in the culture media, levels of SelW, inflammatory genes NF-κB, tumor necrosis factor (TNF)-α, p53, and the cell cycle were analyzed. Furthermore, the correlation between SelW and the levels of these factors was determined. The results indicated that Se treatment increased the expression of SelW (P < 0.05) and caused a downregulation of p53, NF-κB, and TNF-α (P < 0.05). In contrast, H2O2 increased the expression of p53, NF-κB, TNF-α, and LDH (P < 0.05) and induced early cell apoptosis, which was alleviated by treatment with Se. In addition, SelW had a positive correlation with the levels of inflammatory genes investigated. Taken together, our findings suggested that SelW is sensitive to Se levels and oxidative stress, and may play a role in the protective function of Se against oxidative damage and inflammation in chicken myocardial cells.

Dietary Selenium Status Regulates the Transcriptions of Selenoproteome and Activities of Selenoenzymes in Chicken Kidney at Low or Super-nutritional Levels

To determine dietary selenium (Se) status regulates the transcriptions of selenoproteome and activities of selenoenzymes in chicken kidney, 1-day-old chickens received low Se (0.028 mg Se per kg of diet) or super-nutritional Se (3.0 or 5.0 mg Se per kg of diet) in their diets for 8 weeks. It was observed that dietary low or super-nutritional Se did not make renal appearance pathological changes in chicken. Low Se significantly reduced total antioxidant capability (T-AOC), glutathione (GSH) content, but malondialdehyde (MDA) content in the kidney increased and decreased glutathione peroxidase (Gpx) and thioredoxin reductase (TrxR) activity with changes in their mRNA levels. Super-nutritional Se (3.0 mg/kg) increased T-AOC and GSH contents then made them reduce, but it reduced MDA content significantly, elevated then reduced Gpx activity, and decreased TrxR activity with changes in their mRNA levels. Dietary low Se downregulated the mRNA expressions of Gpx1-4, Txnrd3, Sepn1, Selw, Sepx1, Selh, and SEPSECS. At super-nutritional Se, most selenoproteins were upregulated in chicken kidney, but Sepp2 and Sep15 was only upregulated in Se excess (5.0 mg/kg) bird. These results indicated that dietary Se status stabilizes normal renal physiology function via regulation of the selenoprotemic transcriptions and selenoenzyme activities in avian.

The Antagonistic Effect of Selenium on Lead Toxicity Is Related to the Ion Profile in Chicken Liver

The interactions between the essential element selenium (Se) and the toxic element lead (Pb) have been reported extensively; however, limited data are available regarding the effects of Se on Pb and the ion profile in chicken liver. Whether the change in the ion profile was involved in the protective process of Se and the toxic effect of Pb is unknown. In the present study, we detected 26 ion profiles (including those of Na, Mg, K, Ca, B, Si, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Mo, Sb, Ba, Tl, Li, Al, As, Cd, Sn, Hg, and Pb) in chicken liver following treatment with Se or Pb and with the compound treatment of Se and Pb. The results showed that Se supplementation decreased the content of B and Cr and increased that of Zn and Ba (P < 0.05); however, Pb exposure decreased Cr, Mn, Cu, Se, Mo, and Hg and increased V, Fe, Cd, and Sn (P < 0.05). The results showed that Se and Pb primarily influenced essential microelements and toxic microelements in the chicken liver. In this process, Se alleviated the increased Cd and Pb induced by Pb exposure but aggravated the decreased Cu and Mn. The results also indicated that there existed both synergistic and antagonistic interactions between different ions, further verifying the principal component analysis. Thus, the results showed that prolonged exposure to Se and Pb influences the ion profiles in chicken liver. The protective role of Se and toxic effect of Pb may be related to these changing ion profiles in chicken liver.

Possible correlation of selenoprotein W with inflammation factors in chicken skeletal muscles

The aim of the present study was to investigate the possible correlation of selenoprotein W (SelW) with inflammatory injury induced by dietary selenium (Se) deficiency in chicken. One-day-old male chickens were fed either a commercial diet or a Se-deficient diet for 55 days. Then, the expression levels of SelW messenger RNA (mRNA) and inflammation-related genes (NF-κB, TNF-α, iNOS, COX-2, and PTGES) in chicken skeletal muscles (wing muscle, pectoral muscle, and thigh muscle) were determined at 15, 25, 35, 45, and 55 days old, respectively. In addition, the correlation between SelW mRNA expression and inflammation-related genes were assessed. The results showed that dietary Se deficiency reduced the mRNA expression of SelW in chicken wing, pectorals, and thigh muscles. In contrast, Se deficiency increased the mRNA expression levels of inflammation-related genes in chicken skeletal muscle tissues at different time points. The Pearson's correlation coefficients showed that the mRNA expression levels of inflammation-related genes were significantly negative related to SelW (p < 0.05). These data showed that Se deficiency induced the inflammatory response in chicken skeletal muscle. As one important selenoprotein gene in skeletal muscles, SelW may play a role in the regulation of inflammation reaction in Se-deficiency myopathy.

Neurologic aspects of multiple organ transplantation

Complex multiorgan failure may require simultaneous transplantation of several organs, including heart-lung, kidney-pancreas, or multivisceral transplantation. Solid organ transplantation can also be combined with hematopoietic stem cell transplantation to modulate immunologic response to a solid organ allograft. Combined multiorgan transplantation may offer a lower rate of allograft rejection and lower immunosuppression needs. In recent years, intestinal and multivisceral transplantations became viable as a rescue treatment for patients with irreversible intestinal failure who can no longer tolerate total parenteral nutrition with 70% survival after 5 years which is comparable to other types of solid organ allografts. Post-transplant neurologic complications were reported in up to 86% of allograft recipients and greatly overlap in intestinal and multivisceral allograft recipients, without a significant effect on the outcome of transplantation. Other common organ combinations in multiorgan transplantation include kidney-pancreas, which is mostly used for patients with renal failure and uncontrolled diabetes, and heart-lung for patients with congenital heart disease and idiopathic pulmonary arterial hypertension. Kidney-pancreas transplantation frequently results in an improvement of diabetic complications, including diabetic neuropathy. Heart-lung allograft recipients have very similar clinical course and spectrum of neurologic complications to lung transplant recipients. At this time there are no reports of an increased risk of graft-versus-host disease with combined transplantation of solid organ allograft and hematopoietic stem cells. Chronic immunosuppression and complex toxic-metabolic disturbances after multiorgan transplantation create a permissive environment for development of a wide spectrum of neurologic complications which largely resemble complications after transplantations of individual components of complex multiorgan allografts.

Dietary selenium influences calcium release and activation of MLCK in uterine smooth muscle of rats

We sought to elucidate the effects of different concentrations of dietary selenium on calcium ion release, MLCK levels, and muscle contraction in the uterine smooth muscle of rats. The selenium (Se) content of blood and of uterine smooth muscle tissues was detected by fluorescence spectrophotometry. Ca(2+) content was measured by atomic absorption spectroscopy. Calmodulin (CaM) and MLCK RNA and protein levels were analyzed by quantitative real-time polymerase chain reaction and Western blot, respectively. Dietary Se intake increased the Se levels in the blood and in uterine smooth muscle tissues and increased the Ca(2+) concentration in uterine smooth muscle tissues. The addition of Se also promoted CaM expression and enhanced MLCK activation in uterine smooth muscle tissues. In conclusion, Ca(2+), CaM, and MLCK were regulated by Se in uterine smooth muscle; Se plays a major role in regulating smooth muscle contraction in the uterus.

Possible correlation between selenoprotein W and myogenic regulatory factors in chicken embryonic myoblasts

The biological function of selenium (Se) is mainly elicited through Se-containing proteins. Selenoprotein W (SelW), one member of the selenoprotein family, is essential for the normal function of the skeletal muscle system. To investigate the possible relationship of Se in the process of differentiation in chicken myoblasts and the expression of SelW, the cultured chicken embryonic myoblasts were incubated with sodium selenite at different concentrations for 72 h, and then the mRNA levels of SelW and myogenic regulatory factors (MRFs) in myoblasts were determined at 12, 24, 48, and 72 h, respectively. Furthermore, the correlation between SelW mRNA expression and MRF mRNA expression was assessed. The results showed that the sodium selenite medium enhanced the mRNA expression of SelW, Myf-5, MRF4, and myogenin in chicken myoblasts. The mRNA expression levels of MRFs were significantly correlated with those of SelW at 24, 48, and 72 h. These data demonstrate that Se is involved in the differentiation of chicken embryonic myoblasts, and SelW showed correlation with MRFs.

Parenteral trace elements in children: clinical aspects and dosage recommendations

PURPOSE OF REVIEW

Since the 1970s, it has been known that the supplementation of trace elements with parenteral nutrition is required in order to avoid the clinical manifestations of their deficiencies. However, the correct level of requirements of these trace elements, particularly in paediatrics, has provided some debate. The recent developments might help revise some of the current recommendations, particularly in short-term parenteral nutrition provision.

RECENT FINDINGS

Parenterally fed preterm neonates require routine addition of zinc. Provision of chromium and manganese in parenteral nutrition should be limited, particularly for short-term patients. Newer parenteral iron preparations provide the opportunity for a safer and larger dose of administration.

SUMMARY

Clinicians should prescribe according to the individual requirements and revise the routine practice of providing 'all in one' parenteral trace elements preparations, as these products do not reflect or allow tailored provision in paediatrics and may increase the risk of toxicity.

The expression of chicken selenoprotein W, selenocysteine-synthase (SecS), and selenophosphate synthetase-1 (SPS-1) in CHO-K1 cells

Selenoprotein W (SelW) has been found to be ubiquitously expressed in tissues in vivo and was purified more than 18 years ago. However, little in vitro research has been performed on SelW from birds. To detect the mRNA levels of chicken SelW in cultured cell lines, chicken SelW cDNA was cloned into an expression vector. The chicken SelW expression construct was then transfected into CHO-K1 cells. Using RT-PCR and real-time quantitative reverse transcription PCR, we detected the expression of the chicken SelW mRNA. Moreover, the selenocysteine-synthase (SecS) and selenophosphate synthetase-1 (SPS-1) mRNA levels were analyzed. The expression of SelW was detected in SelW-transfected cells; no expression was observed in control cells. Significant increases in the SelW mRNA levels were obtained in chicken SelW-transfected cells relative to control cells. SecS mRNA levels were significantly increased in chicken SelW transfected cells. No significant difference in the SPS-1 level was observed. Our findings show that chicken SelW could be studied in vitro and that SecS and SPS-1 may have potential roles in SelW biosynthesis.

Effects of chicken selenoprotein W on H2O2-induced apoptosis in CHO-K1 cells

Selenoprotein W (SelW) is expressed in various tissues of many animals and acts as an oxidoreductase in mammals. However, little is known about the role of the SelW in birds. To investigate the role of the chicken SelW on H(2)O(2)-induced apoptosis in CHO-K1 cells, overexpression of a chicken SelW cell lines (CHO-K1/SelW) were constructed. Using acridine orange/ethidium bromide (AO/EB) double staining and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assays, as well as WST-1 cell viability assay, we monitored the extent of the H(2)O(2)-induced apoptosis and detected the abundance of the caspase-3, caspase-8, and fas mRNA by real-time quantitative reverse transcription PCR (qPCR). We here found that overexpression of SelW cells, compared with the wild-type cells, resulted in a markedly decrease in sensitivity to H(2)O(2)-induced oxidative stress and had a lower apoptotic cell death in AO/EB and TUNEL assays. Cell viability revealed that overexpression of SelW cells had higher cell viability than wild-type cells. qPCR results found that overexpression of SelW cells had a lower levels of caspase-3, caspase-8, and fas mRNA than wild-type cells. Taken together, our findings suggested that SelW could reduce the oxidative damage induced by H(2)O(2) and had an important protective function in against oxidative damage.

Selenium regulates gene expression of selenoprotein W in chicken gastrointestinal tract

Selenoprotein W (SelW) is an existing form of selenium (Se). Se influences the levels of SelW in mammals. However, little is known about the pattern of SelW expression in the gastrointestinal tract tissue of bird. The present paper describes the effects of different dietary levels of Se on the SelW mRNA expression in the gastrointestinal tract tissue of chicken. The expression levels of SelW mRNA and the Se contents in the gastrointestinal tract tissues (glandular stomach, gizzard, duodenum, small intestine, and rectum) were determined on days 15, 25, 35, 45, and 55, respectively. The results showed that the Se contents and the SelW mRNA expression were significantly higher (p < 0.05) in the high-Se group, and the Se contents and SelW mRNA expression in the low-Se group were significantly lower (p < 0.05) than in the controls. The Se contents were the highest in the duodenum and the lowest in the rectum, while the SelW mRNA expression was the highest in the gizzard and the lowest in the rectum. In addition, the SelW mRNA levels in the gastrointestinal tract tissue were found to increase in a time-dependent manner with increasing feeding time. Furthermore, the expression of the SelW mRNA in the gastrointestinal tract tissues of chickens was found to correlate with the dietary Se concentrations, but not with the tissue Se contents.