Selenium and iodine supplementation of rural Tibetan children affected by Kashin-Beck osteoarthropathy

Review on the health-promoting effect of adequate selenium status

Selenium is an essential microelement involved in various biological processes. Selenium deficiency increases the risk of human immunodeficiency virus infection, cancer, cardiovascular disease, and inflammatory bowel disease. Selenium possesses anti-oxidant, anti-cancer, immunomodulatory, hypoglycemic, and intestinal microbiota-regulating properties. The non-linear dose-response relationship between selenium status and health effects is U-shaped; individuals with low baseline selenium levels may benefit from supplementation, whereas those with acceptable or high selenium levels may face possible health hazards. Selenium supplementation is beneficial in various populations and conditions; however, given its small safety window, the safety of selenium supplementation is still a subject of debate. This review summarizes the current understanding of the health-promoting effects of selenium on the human body, the dietary reference intake, and evidence of the association between selenium deficiency and disease.

Progress of Selenium Deficiency in the Pathogenesis of Arthropathies and Selenium Supplement for Their Treatment

Selenium, an essential trace element for human health, exerts an indispensable effect in maintaining physiological homeostasis and functions in the body. Selenium deficiency is associated with arthropathies, such as Kashin-Beck disease, rheumatoid arthritis, osteoarthritis, and osteoporosis. Selenium deficiency mainly affects the normal physiological state of bone and cartilage through oxidative stress reaction and immune reaction. This review aims to explore the role of selenium deficiency and its mechanisms existed in the pathogenesis of arthropathies. Meanwhile, this review also summarized various experiments to highlight the crucial functions of selenium in maintaining the homeostasis of bone and cartilage.

Selenium, TGF-Beta and Infectious Endemic Cardiopathy: Lessons from Benchwork to Clinical Application in Chagas Disease

For over 60 years, selenium (Se) has been known as an essential microelement to many biological functions, including cardiovascular homeostasis. This review presents a compilation of studies conducted in the past 20 years related to chronic Chagas disease cardiomyopathy (CCC), caused by Trypanosoma cruzi infection, a neglected disease that represents a global burden, especially in Latin America. Experimental and clinical data indicate that Se may be used as a complementary therapy to prevent heart failure and improve heart function. Starting from the main questions “Is Se deficiency related to heart inflammation and arrhythmogenesis in CCC?” and “Could Se be recommended as a therapeutic strategy for CCC?”, we show evidence implicating the complex and multidetermined CCC physiopathology, discussing its possible interplays with the multifunctional cytokine TGF-β as regulators of immune response and fibrosis. We present two new proposals to face this global public health challenge in vulnerable populations affected by this parasitic disease: fibrosis modulation mediated by TGF-β pathways and the possible use of selenoproteins as antioxidants regulating the increased reactive oxygen stress present in CCC inflammatory environments. We assess the opportunity to consider the beneficial effects of Se in preventing heart failure as a concept to be applied for CCC patients.

Inherited Disorders of Thyroid Hormone Metabolism Defect Caused by the Dysregulation of Selenoprotein Expression

Consistent activation and functioning of thyroid hormones are essential to the human body as a whole, especially in controlling the metabolic rate of all organs and systems. Impaired sensitivity to thyroid hormones describes any process that interferes with the effectiveness of thyroid hormones. The genetic origin of inherited thyroid hormone defects and the investigation of genetic defects upon the processing of thyroid hormones are of utmost importance. Impaired sensitivity to thyroid hormone can be categorized into three conditions: thyroid hormone cell membrane transport defect (THCMTD), thyroid hormone metabolism defect (THMD), and thyroid hormone action defect (THAD). THMD is caused by defects in the synthesis and processing of deiodinases that convert the prohormone thyroxine (T4) to the active hormone triiodothyronine (T3). Deiodinase, a selenoprotein, requires unique translation machinery that is collectively composed of the selenocysteine (Sec) insertion sequence (SECIS) elements, Sec-insertion sequence-binding protein 2 (SECISBP2), Sec-specific eukaryotic elongation factor (EEFSEC), and Sec-specific tRNA (TRU-TCA1-1), which leads to the recognition of the UGA codon as a Sec codon for translation into the growing polypeptide. In addition, THMD could be expanded to the defects of enzymes that are involved in thyroid hormone conjugation, such as glucuronidation and sulphation. Paucity of inherited disorders in this category leaves them beyond the scope of this review. This review attempts to specifically explore the genomic causes and effects that result in a significant deficiency of T3 hormones due to inadequate function of deiodinases. Moreover, along with SECISBP2, TRU-TCA1-1, and deiodinase type-1 (DIO1) mutations, this review describes the variants in DIO2 single nucleotide polymorphism (SNP) and thyroid stimulating hormone receptor (TSHR) that result in the reduced activity of DIO2 and subsequent abnormal conversion of T3 from T4. Finally, this review provides additional insight into the general functionality of selenium supplementation and T3/T4 combination treatment in patients with hypothyroidism, suggesting the steps that need to be taken in the future.

The Effects of Selenium on Bone Health: From Element to Therapeutics

Osteoporosis, characterized by low bone mass and a disruption of bone microarchitecture, is traditionally treated using drugs or lifestyle modifications. Recently, several preclinical and clinical studies have investigated the effects of selenium on bone health, although the results are controversial. Selenium, an important trace element, is required for selenoprotein synthesis and acts crucially for proper growth and skeletal development. However, the intake of an optimum amount of selenium is critical, as both selenium deficiency and toxicity are hazardous for health. In this review, we have systematically analyzed the existing literature in this field to determine whether dietary or serum selenium concentrations are associated with bone health. In addition, the mode of administration of selenium as a supplement for treating bone disease is important. We have also highlighted the importance of using green-synthesized selenium nanoparticles as therapeutics for bone disease. Novel nanobiotechnology will be a bridgehead for clinical applications of trace elements and natural products.

Effect of Low Nutrition and T-2 Toxin on C28/I2 Chondrocytes Cell Line and Chondroitin Sulfate-Modifying Sulfotransferases

OBJECTIVE

To investigate the effects of low nutrition and trichothecenes-2 toxin (T-2) on human chondrocytes cell line C28/I2 and the gene expression levels of some chondroitin sulfate (CS)-modifying sulfotransferases.

METHODS

The chondrocytes were divided into 4 intervention groups: (a) control group (Dulbecco's modified Eagle's medium/Nutrient Mixture F-12 [DMEM/F-12] with fetal bovine serum [FBS]), (b) low-nutrition group (DMEM/F-12 without FBS), (c) T-2 group (DMEM/F-12 with FBS plus 20 ng/mL T-2), and (d) combined group (DMEM/F-12 without FBS plus 20 ng/mL T-2). Twenty-four hours postintervention, ultrastructural changes in the chondrocytes were observed by transmission electron microscopy (TEM). Live cell staining and methyl thiazolyl tetrazolium (MTT) assay were performed to observe cell viability. The expression of CS-modifying sulfotransferases, including carbohydrate sulfotransferase 3, 12, 13, 15 (CHST-3, CHST-12, CHST-13, and CHST-15, respectively), and uronyl 2-O-sulfotransferase (UST) were examined by quantitative real-time polymerase chain reaction (RT-qPCR) analysis.

RESULTS

The cells in the T-2 group and combined group had significantly lower live cell counts and relative survival rates than the control group. TEM pictures revealed decreased electron density of mitochondria in the low-nutrition group. The T-2 group and combined group both caused mitochondrial swelling, damage, and reduction in mitochondrial number. RT-qPCR showed a trend of altered expression of CHST and increased expression of UST genes under low-nutrition, T-2 toxin and combined interventions.

CONCLUSIONS

These results show early-stage Kashin-Beck disease chondrocyte pathophysiology, consisting of chondrocyte cell damage and compensatory upregulation of CHST and UST genes.

The Effect and Potential Mechanism of Maternal Micronutrient Intake on Offspring Glucose Metabolism: An Emerging Field

Diabetes has become the most common metabolic disease around the world. In addition to genetic and environmental factors in adulthood, the early life environment is critical to the progression of diabetes in adults, especially the environment during the fetal period; this concept is called “fetal programming.” Substantial evidence has illustrated the key role of early life macronutrient in programming metabolic diseases. Recently, the effect of maternal micronutrient intake on offspring glucose metabolism during later life has become an emerging field. This review focuses on updated human and animal evidence about the effect of maternal micronutrient status on offspring glucose metabolism and the underlying mechanism.

Prevalence of pediatric Kashin-Beck disease in Tibet

INTRODUCTION

To estimate the prevalence of Kashin-Beck disease (KBD) among children in 2017 in Changdu of Tibet.

METHODS

We adopted a four-step recruitment to include children aged 7-12 years from seven identified historically endemic counties in Changdu. Posterior-anterior radiographs of right hand and wrist were taken and were graded at four sites (metaphysis, epiphysis, and bony end of phalanges and metacarpal and carpal bones). Two trained researchers independently read the films. Inter-rater reliability was assessed using weighted Kappa and percentage agreement. We fitted logistic regression model to examine the association of age, sex, and altitude of residential village with prevalence of KBD. We examined association between site involvement and severity of KBD using chi-square test.

RESULTS

We recruited 13,573 children (mean age = 9.3 years, 48.40% girls) with a response rate of 95.81%. The overall prevalence of radiographic KBD was 0.26%. Luolong County had the highest prevalence (0.69%), followed by Bianba (0.26%), Basu (0.24%), Mangkang (0.14%), Zuogong (0.14%), Dingqing (0.07%), and Chaya (0.00%). A higher risk of radiographic KBD was associated with older age (P for trend <0.001) and girls (OR=1.86, 95% CI: 0.94, 3.70), but not the altitude of residential village (P for trend=0.957). Metaphysis was involved in all cases of KBD while lesions in epiphysis and bony end of phalanges and metacarpals were only observed in severe cases.

CONCLUSIONS

The prevalence of radiographic KBD among children aged 7-12 years was low in Changdu compared with previous census data, suggesting the effectiveness of preventative measures. Key Points • In this study, 13,573 Tibetan children were taken X-ray films of their hands and wrists. • The prevalence of radiographic KBD among children aged 7-12 years was low in Changdu of Tibet. • The preventative measures against KBD launched by Chinese government were effective in decreasing new onsets of KBD among Tibetan children.

Comprehensive analysis of lncRNA and mRNA based on expression microarray profiling reveals different characteristics of osteoarthritis between Tibetan and Han patients

Background

Osteoarthritis (OA) is thought to be the most prevalent chronic joint disease, especially in Tibet of China. Here, we aimed to explore the integrative lncRNA and mRNA landscape between the OA patients of Tibet and Han.

Methods

The lncRNA and mRNA expression microarray profiling was performed by SurePrint G3 Human Gene Expression 8x60K v2 Microarray in articular cartilage samples from OA patients of Han nationality and Tibetans, followed by GO, KEGG, and trans-regulation and cis-regulation analysis of lncRNA and mRNA.

Results

We found a total of 117 lncRNAs and 297 mRNAs differently expressed in the cartilage tissues of Tibetans (n = 5) comparing with those of Chinese Han (n = 3), in which 49 lncRNAs and 158 mRNAs were upregulated, and 68 lncRNAs and 139 mRNAs were downregulated. GO and KEGG analysis showed that several unreported biological processes and signaling pathways were particularly identified. LncRNA-mRNA co-expression analysis revealed a remarkable lncRNA-mRNA relationship, in which OTOA may play a critical role in the different mechanisms of the OA progression between Tibetans and Chinese Han.

Conclusion

This study identified different lncRNA/mRNA expression profiling between OA patients of Tibetans and Han, which were involved in many characteristic biological processes and signaling pathways.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02213-y.

T-2 Toxin Induces Epiphyseal Plate Lesions via Decreased SECISBP2-Mediated Selenoprotein Expression in DA Rats, Exacerbated by Selenium Deficiency

OBJECTIVE

Both selenium (Se) deficiency and mycotoxin T2 lead to epiphyseal plate lesions, similar to Kashin-Beck disease (KBD). However, regulation of selenoproteins synthesis mediated by SECISBP2, in response to these 2 environmental factors, remained unclear. The present study proposed to explore the mechanism behind the cartilage degradation resulting from Se deficiency and mycotoxin T2 exposure.

DESIGN

Deep chondrocyte necrosis and epiphyseal plate lesions were replicated in Dark Agouti (DA) rats by feeding them T2 toxin/Se deficiency artificial synthetic diet for 2 months.

RESULTS

Se deficiency led to decreased expression of COL2α1, while T2 treatment reduced the heparan sulfate 6-O-sulfotransferase 2 (HS6ST2) expression, both of which affected the cartilage extracellular matrix metabolism in the rat models. The expression of Col2α1, Acan, Hs6st2, Secisbp2, Gpx1, and Gpx4 were all significantly decreased in cartilage tissues from DA rats, fed a Se-deficient diet or exposed to T2 toxin, contrary to Adamts4, whose expression was increased in both conditions. In addition, T2 treatment led to the decreased expression of SBP2, GPX1, GPX4, and total GPXs activity in C28/I2 cells.

CONCLUSION

DA rats exposed to T2 toxin and/or Se-deficient conditions serve as the perfect model of KBD. The 2 environmental risk factors of KBD, which serve as a "double whammy," can intensify the extracellular matrix metabolic imbalance and the antioxidant activity of chondrocytes, leading to articular cartilage degradation and epiphyseal plate abnormalities similar to those observed in KBD.

Endemic Kashin-Beck disease: A food-sourced osteoarthropathy

OBJECTIVE

Kashin-Beck disease (KBD) is an endemic osteoarthropathy, which causes disability and heavy socioeconomic burdens. The preventive measures have been taken in the past few decades. However, recent KBD-epidemiological trend and comprehensive effect of its preventive measures need to be evaluated.

METHODS

By employing typical survey, cross-sectional survey, case-control study, intervention trial, and national surveillance, the present study summarizes comprehensive role of KBD-preventive measures.

RESULTS

The endemic KBD is distributed in a long and narrow area of the world. The latest epidemic began in the late 1950s and lasted until the end of 1980s. Epidemiology of the KBD was characterized by early-onset, gender equality, agricultural area, regional discrepancy, family aggregation, annual fluctuation, etc. Multivariate regression analysis suggested that etiology of the KBD was food-related factors such as fungal contamination of grains, selenium deficiency, imbalance of protein intake, etc. A series of intervention measures for KBD control had been implemented since 1990s, and involved more than 300 million residents. National incidences were 22.1% in 1990, 16.0% in 1995, 12.3% in 2000, 5.5% in 2005, 0.38% in 2010, and 0.18 in 2015, respectively. Although new patients were annually decreased, it still affected 22,567,600 inhabitants and there were 574,925 patients in 2016.

CONCLUSIONS

Etiology of the KBD is food-sourced. Its decreased incidence may attribute to an effective implementation of preventive measures. It is possible to eradicate KBD from the earth in the near future.

Maintenance of SOX9 stability and ECM homeostasis by selenium-sensitive PRMT5 in cartilage

OBJECTIVES

Selenium (Se) plays pivotal roles in maintaining optimal health. Nevertheless, how Se influences the metabolism of extracellular matrix (ECM) in cartilage remains unclear. The aim of the present study was to observe protein dimethylation by certain Se-sensitive PRMT and to elucidate its effects on the key transcriptional factor in cartilage.

METHODS

We observed the expression of selenoproteins and markers of ECM metabolism in chondrocytes and articular cartilage of the rats under Se-deficiency by RT-qPCR, immunoblotting and immunohistochemistry. Then, we analyzed the expression of total dimethylated protein by using specific antibody under different Se statuses. After Se sensitive PRMT was identified, we used siRNA or PRMT inhibitor or stably overexpressing vector to intervene in the PRMT expression and identified the key transcriptional factor. Co-immunoprecipitation was applied to verify the interaction between PRMT and the key transcriptional factor. Finally, we measured the half-life time of the key transcriptional factor by immunoblotting after cycloheximide treatment.

RESULTS

In chondrocytes and cartilage of the rats with Se deficiency, we found an aberrant metabolism manifesting decreased expression of Col2a1 and increased expression of Mmp-3. Then, we identified that PRMT5 was the unique type II PRMT, sensitive to Se status. PRMT5 upregulation led to the increased COL2A1 expression but decreased MMP-3 expression in chondrocytes. Furthermore, we revealed that PRMT5 improved SOX9 stability by dimethylating the protein, which contributed to maintain the matrix metabolic homeostasis of the chondrocytes.

CONCLUSIONS

Se-sensitive PRMT5 increases the half-life of SOX9 protein via PTM and helps to maintain ECM homeostasis of the articular cartilage.

Ageing and Osteoarthritis

The increase in global lifespan has in turn increased the prevalence of osteoarthritis which is now the most common type of arthritis. Cartilage tissue located on articular joints erodes during osteoarthritis which causes pain and may lead to a crippling loss of function in patients. The pathophysiology of osteoarthritis has been understudied and currently no disease modifying treatments exist. The only current end-point treatment remains joint replacement surgery. The primary risk factor for osteoarthritis is age. Clinical and basic research is now focused on understanding the ageing process of cartilage and its role in osteoarthritis. This chapter will outline the physiology of cartilage tissue, the clinical presentation and treatment options for the disease and the cellular ageing processes which are involved in the pathophysiology of the disease.

Selenium inadequacy hampers thyroid response of young children after iodine repletion

Selenium (Se) is an integral component of iodothyronine deiodinase, glutathione peroxidase and thioredoxin reductase enzymes and thus is important for normal thyroid function. This study investigated the influence of Se inadequacy on thyroid response of iodine-replete young children. Serum thyroxine (T₄), triiodothyronine (T₃), thyroglobulin (Tg), thyroid stimulating hormone (TSH), and Se were analyzed in 54-60 mo old children (n = 628) from the Amhara region of Ethiopia before salt iodization was commenced; analyses were repeated (n = 555) 15 mo after iodized salt became available. Iodized salt coverage increased from 12.2% to 91.6% of households. Median urinary iodine concentration (UIC) among children increased from 9 μg/l to 167 μg/l (p < 0.001). In addition, all thyroid indices except T₃ showed significant improvement (p < 0.05). Nearly, half of the study children (49.1%) had Se inadequacy (serum Se < 70 μg/l). Serum Se was significantly correlated with T₃ (r = 0.38, p < 0.001), T₄ (r = 0.15, p < 0.001), TSH (r=-0.205, p < 0.001) and Tg (r= -0.11, p < 0.01) concentrations 15 mo after iodine repletion; baseline serum Se and T₄(r= -0.22, p < 0.01) were inversely correlated. Despite adequate iodine status, children with low serum Se had lower serum T₄ (p = 0.003) and T₃(p < 0.001) but higher TSH concentration (p = 0.003). In the partial least square regression model, Se was among the latent variables significantly explaining T₄ and T₃. Results of the present study suggest that Se inadequacy negatively affects the thyroid metabolism of iodine-replete children and may present a substantial public health concern thus emphasize the need to consider correction of Se status for normal thyroid function as well as for benefits from its diverse biological roles.

Selenium-sensitive miRNA-181a-5p targeting SBP2 regulates selenoproteins expression in cartilage

Selenium (Se) deficiency brings about defects in the biosynthesis of several selenoproteins and has been associated with aberrant chondrogenesis. Selenocysteine (Sec) Insertion Sequence (SECIS) and SECIS binding protein 2 (SBP2) interaction is a very critical node for the metabolic balance between Se and selenoproteins. The Gpx1, Gpx4 and SelS have different binding affinities with SBP2 in cells. According to our results, both miR‐181a‐5p and SBP2 appeared to be selenium‐sensitive and regulated the expression of selenoproteins in C28/I2 cells under Se sufficient environment. However, they showed significantly opposite expression trend in Se deficiency rats cartilage and SeD C28/I2 cells. The SBP2 is a direct target gene of miR‐181a‐5p in C28/I2 cells as determined by reporter gene and off‐target experiments. And the miR‐181a‐5p could regulate SBP2 and the selenoproteins in C28/I2 cells. Depending upon the Se supply levels, C28/I2 cells were divided into three groups, that is normal Se, SeD and SeS, which underwent through a 7‐day Se deprivation process, then SBP2 was knocked‐down and overexpressed in all the groups. Moreover, the selected selenoproteins were down‐regulated in second‐generation low Se diet rat cartilage. The selenoproteins expression was decreased by Se deficiency which depended on the Selenium‐sensitive miR‐181a‐5p to participate and regulate SBP2 at post‐transcriptional level. It involves a series of antioxidant and ECM (extracellular matrix) genes, to overcome the ROS‐related stress for the protection of essential physiological functions and to maintain the balance between anabolism and catabolism of the cartilage.

Associations Between Selenium Content in Hair and Kashin-Beck Disease/Keshan Disease in Children in Northwestern China: a Prospective Cohort Study

The objective of this study was to investigate the relationship between selenium content in hair and the incidence of Kashin-Beck disease (KBD) and Keshan disease (KD) in China. A prospective cohort study was conducted among children aged 5-12 years with different levels of low-selenium (group 1, Se ≤ 110 ng/g; group 2, 110 < Se ≤ 150 ng/g; and group 3, 150 < Se ≤ 200 ng/g) or selenium-supplemented (group 4, Se > 200 ng/g) exposure. A person-years approach was used to calculate the incidence and rate of positive clinical signs. Relative risk (RR), attributable risk, and etiologic fraction were used to determine the strength of association between selenium and disease incidence. Seven new KBD cases were diagnosed during 3-year follow-up. Positive clinical signs of KBD were found in 17.78 (95% confidence interval [CI] 14.27-21.29) cases per 100 person-years in group 1, 13.28 (9.82-16.74) in group 2, 12.95 (9.34-16.56) in group 3, and 8.18 (5.50-10.85) in group 4. Compared with group 4, the RR (95% CI) of groups 1, 2, and 3 were 2.17 (1.48-3.19), 1.62 (1.07-2.47), and 1.58 (1.03-2.43), respectively. Positive clinical signs of KD were 25.90 (18.62-33.18) cases per 100 person-years in group 1, 5.66 (1.26-10.06) in group 2, 4.60 (0.20-9.00) in group 3, and 14.62 (8.54-20.69) in group 4. Compared with group 4, the RR (95% CI) were 1.77 (1.07-2.93), 0.39 (0.16-0.93), and 0.31 (0.11-0.89), respectively. In children, the onset of KBD was negatively correlated with selenium content within a certain range. However, there may be a U-shaped association between selenium content and KD in children.

Study of rs1137101 polymorphism of leptin receptor gene with serum levels of selenium and copper in the patients of non-ST-segment elevation myocardial infarction (NSTEMI) in an Iranian population

OBJECTIVE

NSTEMI is a type of myocardial infarction (MI) causing partial but progressive occlusion of cardiac coronary vessels. The aim of this study was to investigate rs1137101 polymorphism of soluble leptin receptor (sLEPR) as well as circulatory selenium and copper levels in NSTEMI patients and their usefulness in analyzing susceptibility to NSTEMI.

METHODS

We collected sera and whole blood of 80 NSTEMI patients and 80 healthy individuals using cTnI levels plus electrocardiography as the "gold standard". Polymorphism analysis was done after DNA extraction by high-resolution melt PCR, selenium and copper levels by atomic absorption spectrophotometry, and sLEPR by ELISA.

RESULTS AND DISCUTION

There was Hardy-Weinberg (HWE) equilibrium for both patient and control loci (χ2 = 0.368434509 and 0.341447368, respectively). The frequencies of A/A, A/G, and G/G genotypes were 18 (22%), 37 (46%), and 25 (31%) for patients, and 30 (38%), 36 (45%), and 14 (18%) for healthy controls, respectively. The frequencies of A and G alleles were 73 (46%) and 87 (54%) for patients and 96 (60%) and 64 (40%) for control groups. There was correlation between allele G and sLEPR level and Body Mass Index (BMI). Selenium levels were lower in patient group than control group (66.307 ± 11.013 against 87.488 ± 11.839 μg/L; p < 0.001) but copper concentrations were higher (1.8105 ± 0.358 against 1.366 ± 0.454 mg/L; p < 0.001). sLEPR levels were also higher in patient than control group (30.568 ± 3.290 against 23.740 ± 5.457 ng/dL; p < .001). Low selenium and high copper concentration had positive diagnostic value for disease.

CONCLUSION

We find for the first time that there is a significant association between rs1137101 polymorphism and susceptibility to NSTEMI. There is also statistically meaningful association between decrease in serum selenium and increase in serum copper levels with susceptibility to NSTEMI.

Dietary Selenium Intake and Subclinical Hypothyroidism: A Cross-Sectional Analysis of the ELSA-Brasil Study

Selenium (Se) participates in several enzymatic reactions necessary for regulating the homeostasis of thyroid hormones. We aimed to analyze the association between dietary Se intake and subclinical hypothyroidism. Baseline data from the Longitudinal Study of Adult Health (Estudo Longitudinal de Saúde do Adulto-ELSA-Brasil) in Brazil were analyzed, with a final sample size of 14,283 employees of both sexes aged 35⁻74 years. Dietary data was collected using a previously validated food frequency questionnaire. Subclinical hypothyroidism was categorized as thyroid-stimulating hormone levels of >4.0 IU/mL and free prohormone thyroxine levels within normal limits, without administering drugs for thyroid disease. A multiple logistic regression model was used to assess the relationship between the presence of subclinical hypothyroidism and tertiles of Se consumption. The prevalence of subclinical hypothyroidism in the study sample was 5.4% (95% confidence interval [CI], 3.8⁻7.0%). Compared with the first tertile of Se intake, the second (odds ratio [OR], 0.79; 95% CI, 0.65⁻0.96%) and third (OR, 0.72; 95% CI, 0.58⁻0.90%) tertiles were inversely associated with subclinical hypothyroidism, however further research is needed to confirm the involvement of Se in subclinical hypothyroidism using more accurate methodologies of dietary assessment and nutritional status to evaluate this relationship.

Effects of five types of selenium supplementation for treatment of Kashin-Beck disease in children: a systematic review and network meta-analysis

OBJECTIVE

To compare the effectiveness of five kinds of selenium supplementation for the treatment of patients with Kashin-Beck disease, and rank these selenium supplementations based on their performance.

DESIGN

We searched for all publications between 1 January 1966 and 31 March 2017 using seven electronic databases. GRADE system to network meta-analyses (NMAs) was applied to rate the quality of the evidence. We conducted a random effects model NMA in STATA 12.1 to determine comparative effectiveness of each intervention. Rankings were obtained by using the surface under the cumulative ranking curve (SUCRA) values and mean ranks.

RESULTS

A total of 15 randomised controlled trials involving 2931 patients were included. After assessment of the overall quality of the evidence, we downgraded our primary outcomes from high to low or very low quality. NMAs showed that all five kinds of selenium supplementation had higher metaphysis X-ray improvement which were superior to placebo. Ranking on efficacy indicated that selenium salt was ranked the highest, followed by sodium selenite + vitamin E, selenium enriched yeast, sodium selenite and then sodium selenite + vitamin C.

CONCLUSIONS

Based on the results of NMA, all five types of selenium supplements are more effective than placebo and so that selenium supplementation is of help in repairing metaphyseal lesions. Since the overall quality of the evidence was low or very low, the SUCRA values may be misleading and should be considered jointly with the The Grading of Recommendations Assessment, Development and Evaluation (GRADE) confidence in the estimates for each comparison. The quality of the evidence is insufficient to draw a conclusion about what method of selenium supplementation is most effective.

PROSPERO REGISTRATION NUMBER

CRD42016051874.

Effects of biological factors and health condition on mercury and selenium concentrations in the cartilage, meniscus and anterior cruciate ligament

Due the long-term nature of joint tissue remodeling processes, knee structures including meniscus and anterior cruciate ligament (ACL) can be a model for studying the bioaccumulation of mercury (Hg) and selenium (Se). The accumulation and retention of Hg in human tissues can have a negative effect on the proper functioning of homeostasis-affecting organisms. A factor of chronic poisoning with Hg forms is probably the Se:Hg ratio in tissues. Se:Hg molar ratios below one may increase Hg toxicity potentials, while molar ratios that approach or exceed one effectively may protect against Hg toxicity. Therefore, the aim of the study was to determine total mercury (THg), Se, and Se:THg molar ratios in the cartilage, meniscus and ACL of patients with osteoarthritis (OA) from northwestern Poland. In all studied samples (n=95), we observed higher Se than THg concentration. Taking into consideration the biological factors, we found significantly higher THg levels in the cartilage of women, patients under 65 years of age, patients without hypertension and in the ACL of patients with spinal degenerative disease. We found higher Se levels in the meniscus in women than in men. In all studied parts of the knee joint, we found the Se:THg molar ratio higher than one, which suggests that the joint forming structures are not much exposed to THg. Moreover the results reported here may provide a basis for establishing reference values for the meniscus and ACL in patients with OA who had undergone knee replacement surgery.

Minerals and Trace Elements Intakes and Food Consumption Patterns of Young Children Living in Rural Areas of Tibet Autonomous Region, P.R. China: A Cross-Sectional Survey

BACKGROUND AND OBJECTIVES

Several studies revealed clinical signs of stunting and rickets among rural populations of Tibet Autonomous Region (T.A.R.), and especially amid children. Further, these populations are affected by a bone disease named Kashin-Beck disease (KBD). However, little is known about the dietary status of this population. This survey aimed to assess the usual intakes of young Tibetan children living in rural areas around Lhasa for energy, water, and ten minerals and trace elements (Na, K, Ca, P, Mg, Fe, Zn, Cu, Mn, and Se) involved in bone metabolism.

DESIGN

A cross-sectional survey was designed. Totally, 250 pre-school children aged 3-5 years living in rural areas were enrolled. The 24-h food recall method was used to collect the intakes for two days, during two different seasons (September 2012 and April 2013). Because Tibetan foods are mainly derived from local agriculture and artisanal production, a combination of food composition tables was compiled, including specific and local food composition data.

RESULTS

The Chinese dietary recommended intakes are not met for most of the elements investigated. Intake of sodium is much too high, while usual intakes are too low for K, Ca, Zn, Cu, and Se. Bioavailability of Ca, Fe, and Zn may be of concern due to the high phytic acid content in the diet.

CONCLUSION

These nutrient imbalances may impact growth and bone metabolism of young Tibetan children. The advantages of the implementation of food diversification programs are discussed as well as the relevance of supplements distribution.

Integrative Multivariate Logistic Regression Analysis of Risk Factors for Kashin-Beck disease

To determine the current evidence on risk factors for Kashin-Beck disease (KBD) using an integrative meta-analysis. We searched five English and three Chinese databases from inception to September 2015, to identify case-control studies that examined risk factors for KBD using multivariate logistic analysis. DerSimonian and Laird effective models are applied in processing data using pooled odds ratios (ORs) and 95 % confidence intervals (CI). Seven studies were identified with 3087 cases and 6402 controls. The main risk factors found to be significantly associated with the onset of KBD were age (OR 1.19, 95 % CI 1.10-1.28), parents prevalence (OR 5.16, 2.51-7.80), family hygiene (OR 1.68, 1.42-1.93), food source (OR 3.29, 2.38-4.19), wheat (OR 1.12, 1.08-1.16), wheat germ necrosis rate (OR 6.03, 1.87-12.92), total volatile basic nitrogen (OR 6.85, 1.01-28.67), low selenium in hair (OR 2.29, 1.08-3.50) were found to be significant risks factors. The pooled ORs (95 % CI) of protein intake and rice were 0.79 (0.66-0.93) and 0.90 (0.86-0.95), respectively, indicating that the two factors may be protective for KBD. We found that the combination of low protein intake, polluted grain, and selenium deficiency may contribute to be onset of KBD together.

Association between household unavailability of iodized salt and child growth: evidence from 89 demographic and health surveys

BACKGROUND

Although a strong biological basis exists for a role of iodine in somatic growth failure in childhood, this relation has not been previously studied on a large scale to our knowledge.

OBJECTIVE

We investigated if a general association exists between the household unavailability of iodized salt and child growth across countries.

DESIGN

We used 89 nationally representative, repeated, cross-sectional and mutually comparable demographic and health surveys that were conducted between 1994 and 2012 across 46 low- and middle-income countries. We analyzed the data for the outcome variables of stunting (low height-for-age), underweight (low weight-for-age), wasting (low weight-for-height), and low birth weight in children aged between 0 and 59 mo at the time of the interview with the use of logistic regression models. Our samples consisted of 390,328 children for the stunting analysis, 397,080 children for the underweight analysis, 384,163 children for the wasting analysis, and 187,744 children for the low-birth-weight analysis. Models were adjusted for individual, maternal, and household covariates and fixed effects on the level of the primary sampling unit.

RESULTS

In the fully adjusted models, the unavailability of iodized salt was associated with 3% higher odds of being stunted (95% CI of ORs: 1.00, 1.06; P = 0.04), 5% higher odds of being underweight (95% CI: 1.02, 1.09; P < 0.01), and 9% higher odds of low birth weight (95% CI: 1.02, 1.17; P = 0.01). When India was excluded from the sample, the association was only statistically significant (P = 0.05) for low birth weight.

CONCLUSION

Although we did not establish causality in our analysis, the findings might indicate that the causal effect of iodized salt on child growth, if it exists, is most profound in utero and is not universally effective across all countries with respect to longer-run child-growth outcomes such as stunting and underweight.

The Synergistic Effect of Serine with Selenocompounds on the Expression of SelP and GPx in HepG2 Cells

We explored the synergistic effect of serine combined with several selenocompounds or used alone on the expression of selenoprotein P (SelP) and glutathione peroxidase (GPx) in this study. We first compared the SelP and GPx expression difference between HepG2 and Hela cells treated with serine and finally chose HepG2 as experimental cell. In the serine-used-alone experiment, three kinds of selenium nutritional models (low-, adequate-, and high-selenium) were established and serine was 10 times gradient diluted (0.01 to 100 μmol/L). In the combined experiment, the selenocompound doses were set as 0.01, 0.1, and 1 μmol Se/L and serine was set according to its molar ratio with the selenocompounds. We found that SelP and GPx concentrations in the low-, adequate-, and high-selenium models increased following with serine dose. When the concentration of sodium selenite and SeMet was 1 μmol Se/L while MeSeCys was 0.1 and 1 μmol Se/L, SelP concentrations for serine combined with selenocompounds groups were significantly higher than that of selenocompounds used alone. When the concentration of sodium selenite was 0.1 μmol Se/L, SeMet was 0.1 and 1 μmol Se/L while MeSeCys was 0.01 and 1 μmol Se/L, GPx concentrations for serine combined with selenocompounds groups were significantly higher than that of selenocompounds used alone. Our preliminary result indicated the beneficial effect of serine on the expression of SelP and GPx, which suggested that it might be a candidate for combined selenium supplement.

Positive correlation of thyroid hormones and serum copper in children with congenital hypothyroidism

Thyroid hormones are of central relevance for growth and development. However, the underlying molecular mechanisms are still not fully understood. Recent studies in humans and mice have demonstrated that serum levels of selenium (Se) and copper (Cu) are positively affected by thyroid hormones. Given the importance of these trace elements for many biochemical processes, we tested whether this interaction is found in children at risk for hypothyroidism, potentially providing a novel factor contributing to the disturbed development observed in congenital hypothyroidism (CH). We conducted a cross-sectional analysis of 84 children diagnosed with CH displaying a wide range of thyroid hormone concentrations. Serum Se and Cu concentrations were measured by total reflection X-ray fluorescence. Data for thyrotropin (TSH) were available in all, thyroxine (T4) and free thyroxine (fT4) in the majority and triiodothyronine (T3) in 29 of the children. Spearman rank analyzes were performed. Cu and thyroid hormones showed a strong positive correlation (Cu/T4, rho=0.5241, P=0.0003; Cu/T3, rho=0.6003, P=0.0006). Unlike in adults, no associations were found between Se and any of the thyroid hormones. Our data highlight that serum Cu and thyroid hormones are strongly associated already in early postnatal life. Severely hypothyroid children are thus at risk of developing a Cu deficiency if not adequately nourished or supplemented. This finding needs to be verified in larger groups of children in order not to miss an easily-avoidable risk factor for poor development.

Selenoproteins and oxidative stress-induced inflammatory tumorigenesis in the gut

Selenium is an essential micronutrient that is incorporated into at least 25 selenoproteins encoded by the human genome, many of which serve antioxidant functions. Because patients with inflammatory bowel disease (IBD) demonstrate nutritional deficiencies and are at increased risk for colon cancer due to heightened inflammation and oxidative stress, selenoprotein dysfunction may contribute to disease progression. Over the years, numerous studies have analyzed the effects of selenoprotein loss and shown that they are important mediators of intestinal inflammation and carcinogenesis. In particular, recent work has focused on the role of selenoprotein P (SEPP1), a major selenium transport protein which also has endogenous antioxidant function. These experiments determined SEPP1 loss altered immune and epithelial cellular function in a murine model of colitis-associated carcinoma. Here, we discuss the current knowledge of SEPP1 and selenoprotein function in the setting of IBD, colitis, and inflammatory tumorigenesis.

The roles of selenium, insulin-like growth factor binding protein 2 and suppressor of cytokine signaling 3 in the pathogenesis of Kashin-Beck disease

We aimed to verify the levels of IGFBP2 and SOCS3 in cartilage and chondrocytes of Kashin-Beck disease (KBD) patients and the effects of different selenium concentrations on the protein expression levels. Chondrocytes were cultured with sodium selenite in vitro. Immunohistochemistry and western blotting were used to verify the protein expressions. IGFBP2 and SOCS3 were up-regulated in KBD chondrocytes and decreased with increasing selenium concentrations. IGFBP2 expressed highest in the middle zone of KBD cartilage, SOCS3 expressed higher in the middle and deep zone. IGFBP2 and SOCS3 may be the biomarkers for KBD diagnosis and evaluating the effect of selenium supplement.

Selenium and Iodine Levels in Subjects with Kashin-Beck Disease: a Meta-analysis

Kashin-Beck disease (KBD) is an endemic, degenerative osteoarthropathy, and particularly seen in China. A deficiency of selenium and iodine is implicated as the main etiological factor for KBD. This meta-analysis aimed to evaluate the differences in the selenium and iodine levels between patients with KBD and healthy individuals. Eligible articles published before March 6, 2015 were searched from four electronic databases. Data extraction and quality assessment of included studies were performed by two independent reviewers. Results were summarized as standardized mean difference (SMD) with 95 % confidence intervals (CIs). Cohen's d test was used to estimate the difference of the effect size between patients with KBD and healthy controls. A total of 26 cross-sectional studies were included in the meta-analysis. The pooled SMD showed that the whole blood selenium (Cohen's d = 4.39, P < 0.001), serum selenium (Cohen's d = 2.42, P = 0.015), hair selenium (Cohen's d = 5.46, P < 0.001), and urinary selenium (Cohen's d = 4.16, P < 0.001) levels were significantly lower in patients with KBD than that in healthy controls. There was no significant difference of plasma selenium (Cohen's d = 0.08, P = 0.936) and urinary iodine (Cohen's d = 0.33, P = 0.744) levels between subjects with KBD and healthy controls. In conclusion, the levels of selenium, but not iodine were significantly lower in subjects with KBD than that in healthy controls. Selenium deficiency might be associated with the risk of KBD.

The Roles of the Interaction of BCL2-Antagonist/Killer 1, Apoptotic Peptidase Activating Factor 1 and Selenium in the Pathogenesis of Kashin-Beck Disease

BCL2-antagonist/killer 1 (BAK1) and apoptotic peptidase activating factor 1 (APAF1) are significant genes in apoptosis signalling pathway of Kashin-Beck disease (KBD). We aimed to verify the protein expression levels of BAK1 and APAF1 in the cartilage and chondrocytes of patients with KBD. Additionally, we explored the relationship between the levels of these proteins and selenium concentration. Chondrocytes was cultured and treated with sodium selenite in vitro. Immunohistochemistry and Western blotting were used to verify the expression levels of BAK1 and APAF1. Compared with the control samples, APAF1 was upregulated and BAK1 was downregulated in the cartilage and chondrocytes of KBD patients. APAF1 expression was higher in the middle and deep zone in the KBD cartilage. APAF1 levels decreased gradually with the increasing selenium concentration (0.05, 0.10 and 0.25 mg/L). BAK1 expression in the 0.25 mg/L selenium group was lower than that of the control group. Different selenium concentrations had varying effects on BAK1 and APAF1 levels. APAF1 may play an important role in the pathogenesis of KBD. APAF1-related apoptosis was more pronounced in the middle and deep zones of the KBD cartilage. APAF may represent a potentially novel molecular target, which may be a biomarker of the role of selenium on the prevention and treatment of KBD. The role of BAK1 in the pathogenesis of KBD requires further study.

Hair Selenium Levels of School Children in Kashin-Beck Disease Endemic Areas in Tibet, China

Previous studies have shown that the selenium (Se) deficiency is an important factor for the etiology of Kashin-Beck disease (KBD). Although KBD is presently controlled in most regions of China, it is still active in the Tibetan Plateau. The present study aimed to assess the nutritional status of selenium in school children by using the Se level in hair as a biomarker in KBD endemic areas of Lhasa in Tibet, China. Hair samples of 155 school children aged 6-15 years were collected in both KBD areas and non-KBD areas of Lhasa in 2013. The Se level in the hair samples was determined by inductive coupled plasma mass spectrometry (ICP-MS). The average concentration of Se in children's hair was 0.232 μg/g in KBD areas of Lhasa, which was significantly higher than the data reported decades ago. A significant difference in hair Se was observed between the boys (0.255 μg/g) and the girls (0.222 μg/g) in the studied KBD areas (P < 0.01, Mann-Whitney U test), but hair Se did not vary by age or region. School children in KBD endemic areas in Lhasa likely have improved Se status as a result of high Se content staple food substitution with the enforcement of Free Education Policy and Nutrition Improvement Plan in Tibet. Nevertheless, there were still 20.3 % of students with low Se status (hair Se <0.20 μg/g), which showed that Se status of school children was also partly affected by low Se environment in KBD endemic areas of Lhasa.

Effects of thirty elements on bone metabolism

The human skeleton, made of 206 bones, plays vital roles including supporting the body, protecting organs, enabling movement, and storing minerals. Bones are made of organic structures, intimately connected with an inorganic matrix produced by bone cells. Many elements are ubiquitous in our environment, and many impact bone metabolism. Most elements have antagonistic actions depending on concentration. Indeed, some elements are essential, others are deleterious, and many can be both. Several pathways mediate effects of element deficiencies or excesses on bone metabolism. This paper aims to identify all elements that impact bone health and explore the mechanisms by which they act. To date, this is the first time that the effects of thirty minerals on bone metabolism have been summarized.

Seasonal variation in the input of atmospheric selenium to northwestern Greenland snow

Oxygen isotope ratio (δ(18)O) and concentrations of Al, Na(+), methanesulfonic acid (MSA), SO4(2-), and selenium (Se) in a continuous series of 70 snow samples from a 3.2-m snow pit at a site in northwestern Greenland were determined using ultraclean procedures. Well-defined depth profiles of δ(18)O, Al, and sea-salt-Na(+) allowed the determination of chronology of the snow pit that spanned approximately 6 years from spring 2003 to summer 2009. Se concentrations were at a low pg/g level, ranging from 7.2 to 45 pg/g, and exhibited high variability with generally higher values during winter and spring and lower values during summer and fall. Very high crustal enrichment factors (EFc) of Se averaging approximately 26,600 for the entire time period indicate a small contribution from crust dust. High Se/MSA ratios are generally observed in the winter and spring snow layers, in which the Se concentrations were relatively high (>20 pg/g). This suggests that a significant component of the Se present in the snow layers is of anthropogenic origin. During the summer season, however, high EFc values are accompanied with low Se/MSA, indicating an increased contribution of marine biogenic sources. Significant correlations between Se, Al, and non-sea-salt SO4(2-) highlight that significant inputs of Se to the snow are likely controlled by the seasonality in the transport efficiency of anthropogenic Se from the source regions to the site. Based on the seasonal changes in Se concentrations, Se/MSA, and Se/S ratios observed in the samples, the input of anthropogenic Se to the site appears to be governed by the long-range transportation of Se emitted from coal combustion in East Asian countries, especially in China.

Effects of the consumption of rice from non-KBD areas and selenium supplementation on the prevention and treatment of paediatric Kaschin-Beck disease: an epidemiological intervention trial in the Qinghai Province

OBJECTIVE

Based on the aetiological hypothesis of Kaschin-Beck disease (KBD), different interventions were adopted, and the preventive and therapeutic effects of interventions was observed and evaluated in this trial.

DESIGN

A total of 358 children from seven villages of Qinghai Province in China were examined, and 280 children aged 6-11 years old were eligible for the trial. The children were divided into three groups that received either no intervention (n = 64), 150 kg/person of rice from non-KBD areas (n = 103) or 7 kg/family of selenium-iodine salt (n = 113) for 12 months. Data were collected and used to calculate the proportion of patients with X-ray lesions, the proportion of new patients and the metaphyseal repair rate. All indicators were analysed with Pearson chi-square or Fisher's exact tests. The registration number of this trial is ChiCTR-PNRC-12002309 (http://www.chictr.org).

RESULTS

After interventions, the proportion of patients with X-ray lesions increased dramatically in the control group and decreased significantly in two intervention groups; significant differences were seen between the control group and two intervention groups (P < 0.05). Moreover, significant differences were observed in the proportions of new patients and the metaphyseal repair rates between the control group and two intervention groups (P < 0.05). Additionally, the proportion of new patients was lowest and the metaphyseal repair rate was highest in group B.

CONCLUSIONS

The effects of eating rice from non-KBD areas and selenium supplementation on the prevention and treatment of paediatric KBD were notable, the consumption of rice might be the most effective and safest intervention and should be encouraged.

Recent advances in the research of an endemic osteochondropathy in China: Kashin-Beck disease

Kashin-Beck disease (KBD) is an endemic chronic osteochondral disease, which has a high prevalence and morbidity in the Eastern Siberia of Russia, and in the broad diagonal, northern-east to southern-west belt in China and North Korea. In 1990's, it was estimated that in China 1-3 million people had some degree of symptoms of the disease, although even higher estimates have been presented. In China, the extensive prevalence peaked in the late 1950's, but since then, in contrast to the global trend of the osteoarthritis (OA), the number of cases has been dramatically falling. Up to 2013, there are 0.64 millions patients with the KBD and 1.16 millions at risk in 377 counties of 13 provinces or autonomous regions. This is obviously thanks to the preventive efforts carried out, which include providing millions of people with dietary supplements and clean water, as well as relocation of whole villages in China. However, relatively little is known about the molecular mechanisms behind the cartilage damage, the genetic and the environmental risk factors, and the rationale of the preventive effects. During the last decade, new data on a cellular and molecular level has begun to accumulate, which hopefully will uncover the grounds of the disease.

The phenomenon of micronutrient deficiency among children in China: a systematic review of the literature

OBJECTIVE

The present study aimed to review the literature on micronutrient deficiency and other factors influencing a deficiency status among children living in China.

DESIGN

A systematic review was performed to analyse the literature.

SETTING

Studies were identified through a search of PubMed and secondary references.

SUBJECTS

Children living in China aged less than 18 years.

RESULTS

Sixty-one articles were included. The prevalence of vitamin A deficiency decreased to approximately 10 % in 1995-2009. It increased with age but no significant difference was found between genders. The prevalence of thiamin and vitamin B12 deficiency was 10·5 % in Yunnan and 4·5 % in Chongqing provinces, respectively. Higher vitamin D deficiency rates were seen in spring and winter. The incidence of bleeding due to vitamin K deficiency was 3·3 % in 1998-2001 and more prevalent in rural areas. Both iodine deficiency and excess iodine intake were observed. Goitre rates were reported in Tibet, Jiangxi, Gansu and Hong Kong (3·5-46 %). Anaemia rates ranged from 20 % to 40 % in 2007-2011. High Se deficiency rates were found in Tibet, Shaanxi and Jiangsu. High Zn deficiency rates were also found (50-70 %) in 1995-2006. Few studies reported Ca deficiency rates (19·6-34·3 %). The degrees of deficiency for vitamin A, vitamin B12, Fe and Zn were more substantial in rural areas compared with urban areas.

CONCLUSIONS

The prevalence of micronutrient deficiency rates varied. Socio-economic status, environmental factors and the Chinese diet may influence micronutrient deficiency. Public health policies should consider implementing programmes of supplementation, food fortification and nutrition education to address these deficiencies among Chinese children.

SodiUm SeleniTe Adminstration IN Cardiac Surgery (SUSTAIN CSX-trial): study design of an international multicenter randomized double-blinded controlled trial of high dose sodium-selenite administration in high-risk cardiac surgical patients

Background

Cardiac surgery has been shown to result in a significant decrease of the antioxidant selenium, which is associated with the development of multiorgan dysfunction and increased mortality. Thus, a large-scale study is needed to investigate the effect of perioperative selenium supplementation on the occurrence of postoperative organ dysfunction.

Methods/Design

We plan a prospective, randomized double-blind, multicenter controlled trial, which will be conducted in North and South America and in Europe. In this trial we will include 1,400 high-risk patients, who are most likely to benefit from selenium supplementation. This includes patients scheduled for non-emergent combined and/or complex procedures, or with a predicted operative mortality of ≥5% according to the EuroSCORE II. Eligible patients will be randomly assigned to either the treatment group (bolus infusion of 2,000 μg sodium selenite immediately prior to surgery, followed by an additional dosage of 2,000 μg at ICU admission, and a further daily supplementation of 1,000 μg up to 10 days or ICU discharge) or to the control group (placebo administration at the same time points).

The primary endpoint of this study is a composite of 'persistent organ dysfunction’ (POD) and/or death within 30 days from surgery (POD + death). POD is defined as any need for life-sustaining therapies (mechanical ventilation, vasopressor therapy, mechanical circulatory support, continuous renal replacement therapy, or new intermittent hemodialysis) at any time within 30 days from surgery.

Discussion

The SUSTAIN-CSX™ study is a multicenter trial to investigate the effect of a perioperative high dosage sodium selenite supplementation in high-risk cardiac surgical patients.

Trial registration

This trial was registered at Clinicaltrials.gov (identifier: NCT02002247) on 28 November 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-339) contains supplementary material, which is available to authorized users.

Selenoproteins and selenium status in bone physiology and pathology

BACKGROUND

Emerging evidence supports the view that selenoproteins are essential for maintaining bone health.

SCOPE OF REVIEW

The current state of knowledge concerning selenoproteins and Se status in bone physiology and pathology is summarized.

MAJOR CONCLUSIONS

Antioxidant selenoproteins including glutathione peroxidase (GPx) and thioredoxin reductase (TrxR), as a whole, play a pivotal role in maintaining bone homeostasis and protecting against bone loss. GPx1, a major antioxidant enzyme in osteoclasts, is up-regulated by estrogen, an endogenous inhibitor of osteoclastogenesis. TrxR1 is an immediate early gene in response to 1α,25-dihydroxyvitamin D3, an osteoblastic differentiation agent. The combination of 1α,25-dihydroxyvitamin D3 and Se generates a synergistic elevation of TrxR activity in Se-deficient osteoblasts. Of particular concern, pleiotropic TrxR1 is implicated in promoting NFκB activation. Coincidentally, TrxR inhibitors such as curcumin and gold compounds exhibit potent osteoclastogenesis inhibitory activity. Studies in patients with the mutations of selenocysteine insertion sequence-binding protein 2, a key trans-acting factor for the co-translational insertion of selenocysteine into selenoproteins have clearly established a causal link of selenoproteins in bone development. Se transport to bone relies on selenoprotein P. Plasma selenoprotein P concentrations have been found to be positively correlated with bone mineral density in elderly women.

GENERAL SIGNIFICANCE

A full understanding of the role and function of selenoproteins and Se status on bone physiology and pathology may lead to effectively prevent against or modify bone diseases by using Se.

Association study of polymorphisms in selenoprotein genes and Kashin-Beck disease and serum selenium/iodine concentration in a Tibetan population

BACKGROUND

Kashin-Beck disease is a kind of degenerative osteoarthropathy. Genetic factors may play an important role in the pathogenesis of KBD.

OBJECTIVE

To investigate the association of the selenoprotein genes GPX1 (rs1050450, rs1800668, and rs3811699), TrxR2 (rs5748469), and DIO2 (rs225014) with Kashin-Beck disease (KBD) in a Tibetan population and to investigate the association of these SNPs with the serum iodine/selenium concentration in the Tibetan population.

DESIGN

Five SNPs including rs1050450, rs1800668, and rs3811699 in the GPX1 gene, rs5748469 in the TrxR2 gene, and rs225014 in the DIO2 gene were analyzed in Tibetan KBD patients and controls using the SNaPshot method. P trend values of the SNPs were calculated using an additive model.

RESULTS

None of the five SNPs in the three genes showed a significant association with KBD. Haplotypes TCC, TTC and TTT of rs1050450, rs1800668 and rs3811699 in GPX1 showed a significant association with KBD and controls with P value of 0.0421, 5.0E-4 and 0.0066, respectively. The GPX1 gene (rs1050450) showed a potential significant association with the iodine concentration in the Tibetan study population (P = 0.02726). However, no such association was detected with the selenium concentration (P = 0.2849).

CONCLUSIONS

In this study, we showed that single SNPs in the genes GPX1 (rs1050450, rs1800668 and rs3811699), TrxR2 (rs5748469), and DIO2 (rs225014) may not be significantly associated with KBD in a Tibetan population. However, haplotype analysis of SNPs rs1050450, rs1800668 and rs3811699 in GPX1 gene showed a significant association with KBD. The results suggested that GPX1 gene play a protective role in the susceptivity of KBD in Tibetans. Furthermore, the GPX1 gene (rs1050450) may be significantly associated with the serum iodine concentration in Tibetans.

Selenium: a protective factor for Kaschin-Beck disease in Qing-Tibet Plateau

There is a close relationship between selenium deficiency and Kaschin-Beck disease (KBD). Although the etiology of KBD is not known and selenium deficiency is not its actual cause, it is an important environmental risk factor. In particular, in the Qing-Tibet Plateau, a selenium-deficient region, the prevalence of KBD is serious and still increasing and continues to damage public health. By providing selenium to the population in appropriate amounts, and especially to children, KBD can be effectively controlled and prevented.

Effects of dietary factors on selenium levels of children to prevent Kashin-Beck disease during a high-prevalence period in an endemic area: a cohort study

Selenium (Se) supplements have been used to control Kashin-Beck disease (KBD) for decades, but the effect of diet without Se supplements is unclear because the prevalence of KBD has decreased. This matched cohort study was undertaken to determine dietary factors affecting selenium nutrition status of children living in KBD areas and the effects of Se supplements in preventing KBD. A total of 593 children aged 5-12 years were randomly selected during the high prevalence period of KBD from 1992 to 1995. Children in one village received Se supplemented (Se+) salt and were matched with three children in 16 other villages who did not receive Se supplemented (Se-) salt. A questionnaire and determinations of occipital hair Se to reflect body Se status were obtained at baseline (April 1992), at 6 months (October 1992), and yearly each April through 1995. Hair Se content in the Se+ group was significantly higher than in the Se- group (P < 0.001) at all time-points and was significantly related to the incidence of suspected KBD symptoms (P = 0.018). Four dietary factors significantly affected hair Se contents. Se levels were increased by consumption of Se+ salt (P < 0.001) and eating meat/egg often (P = 0.019) or occasionally (P = 0.001). Se levels were decreased by consumption of grain mildewed at harvest or in storage (P < 0.001 for each) and drinking ditch, river, or cellar water (P < 0.001; P = 0.002; P < 0.001, respectively). These results show that Se+ salt had a significant effect in maintaining the Se nutrition status of children in this cohort study but that dietary factors in those without Se supplements contributed as well.

Genetic variants in the HLA-DRB1 gene are associated with Kashin-Beck disease in the Tibetan population

OBJECTIVE

To investigate the association between variants in the HLA-DRB1 gene and Kashin-Beck disease (KBD), as well as associations of selenium and iodine deficiencies with KBD in a Tibetan population.

METHODS

Fourteen single-nucleotide polymorphisms (SNPs) were genotyped around the HLA-DRB1 gene, and HLA-DRB1 allele genotyping was performed in a discovery cohort, composed of 605 patients with KBD and 393 control subjects, and/or a replication cohort, composed of 290 patients with KBD and 295 controls. Plasma concentrations of selenium and iodine were measured and compared by t-test in 299 patients with KBD and 280 controls from the same villages.

RESULTS

Four SNPs (rs6457617, rs6457620, rs9275295, and rs7745040) in the HLA-DRB1 gene locus were significantly associated with KBD in both the discovery cohort and replication cohort (combined cohort odds ratios [ORs] 1.307-1.402, P = 0.0039-0.0006). The protective haplotype GTCC and the risk haplotype ACGT, each generated by the 4 SNPs, showed a significant association with KBD (for GTCC, OR 0.77, P = 0.0031; for ACGT, OR 1.40, P = 0.0014). HLA-DRB1 allele genotyping revealed that the frequencies of HLA-DRB1*08 and *11 were significantly different between patients with KBD and controls (for HLA-DRB1*08, OR 0.731, P = 0.00564; for HLA-DRB1*11, OR 0.489, P = 0.000395). Moreover, plasma concentrations of selenium and iodine were significantly different between patients with KBD and controls from the same villages (P = 0.0013 and P = 1.84 × 10(-12) , respectively).

CONCLUSION

These findings, obtained in plasma samples from Tibetan patients with KBD and healthy control subjects from the same regions, confirm the role of selenium and iodine deficiencies in the development of KBD. Moreover, genetic variants in the HLA-DRB1 gene significantly increase the susceptibility to KBD in this population.

Selenium. Role of the essential metalloid in health

Selenium is an essential micronutrient in mammals, but is also recognized as toxic in excess. It is a non-metal with properties that are intermediate between the chalcogen elements sulfur and tellurium. Selenium exerts its biological functions through selenoproteins. Selenoproteins contain selenium in the form of the 21st amino acid, selenocysteine (Sec), which is an analog of cysteine with the sulfur-containing side chain replaced by a Se-containing side chain. Sec is encoded by the codon UGA, which is one of three termination codons for mRNA translation in non-selenoprotein genes. Recognition of the UGA codon as a Sec insertion site instead of stop requires a Sec insertion sequence (SECIS) element in selenoprotein mRNAs and a unique selenocysteyl-tRNA, both of which are recognized by specialized protein factors. Unlike the 20 standard amino acids, Sec is biosynthesized from serine on its tRNA. Twenty-five selenoproteins are encoded in the human genome. Most of the selenoprotein genes were discovered by bioinformatics approaches, searching for SECIS elements downstream of in-frame UGA codons. Sec has been described as having stronger nucleophilic and electrophilic properties than cysteine, and Sec is present in the catalytic site of all selenoenzymes. Most selenoproteins, whose functions are known, are involved in redox systems and signaling pathways. However, several selenoproteins are not well characterized in terms of their function. The selenium field has grown dramatically in the last few decades, and research on selenium biology is providing extensive new information regarding its importance for human health.

Clinical features of Kashin-Beck disease in adults younger than 50 years of age during a low incidence period: severe elbow and knee lesions

More than one million people are affected by Kashin-Beck disease (KBD) in a limited endemic area. However, few studies focused on the clinical features of adult KBD patients. The aim of this study was to investigate the clinical features of adult KBD patients who were younger than 50 years of age during a low incidence period. A special questionnaire was designed that surveyed general data, clinical symptoms, and signs and included the Visual Analogue Scale (VAS). Anthropometrics, the joint VAS, the range of joint motion (ROM), and joint function were measured. The VAS and joint dysfunction were compared among the different joints of extremities, and the relationship among the VAS, ROM, age, course of KBD, and number of enlarged knee and elbow joints elbow was analyzed. Two hundred forty-nine adult Tibetan KBD patients, matched with 249 healthy control subjects, have been surveyed. The VAS results show that the knee is the joint associated with the most pain, followed by the elbow. The elbow shows a higher percentage of limited ROM (47.0 %). The number of enlarged joints has a significant correlation with the VAS or elbow and knee ROM compared with the age or course of disease (P < 0.05). Severe elbow and knee lesions are important clinical features of KBD in adults younger than 50 years of age during a low incidence period. The number of enlarged joints can partially predict the VAS or ROM of elbow and knee and may be used for evaluating the patient's condition and function.

Altered Aggrecan Synthesis and Collagen Expression Profiles in Chondrocytes from Patients with Kashin—Beck Disease and Osteoarthritis

OBJECTIVES: To investigate cell morphology, aggrecan expression, and type I, II, III and X collagen expression in chondrocytes from adults with Kashin—Beck disease or osteoarthritis (OA). METHODS: Samples of knee articular cartilage were taken during surgery; cartilage samples obtained from fresh cadavers without arthritic disease were used as controls. Samples were digested with collagenase; isolated chondrocytes were cultured in monolayers. Aggrecan was detected by toluidine blue staining; collagen and aggrecan protein levels were evaluated by immuno cytochemistry and immunofluorescence staining. RESULTS: Samples were obtained from six participants per group. Aggrecan and type II collagen levels in chondrocytes from patients were significantly lower than those from controls, but levels of type I, III and X collagen were enhanced in patients compared with controls. Production of type III and X collagen was higher in chondrocytes from patients with Kashin—Beck disease than in those from OA patients. CONCLUSIONS: Biochemical and morphological mechanisms underlying Kashin—Beck disease and OA include enhanced dedifferentiation and hypertrophy of chondrocytes, increased type I, III and X collagen levels, and suppressed type II collagen and aggrecan production compared with control samples.