Suboptimal selenium supply--a continuing problem in Keshan disease areas in Heilongjiang province

Selenoproteins and tRNA-Sec: regulators of cancer redox homeostasis

In the past two decades significant progress has been made in uncovering the biological function of selenium. Selenium, an essential trace element, is required for the biogenesis of selenocysteine which is then incorporated into selenoproteins. These selenoproteins have emerged as central regulators of cellular antioxidant capacity and maintenance of redox homeostasis. This review provides a comprehensive examination of the multifaceted functions of selenoproteins with a particular emphasis on their contributions to cellular antioxidant capacity. Additionally, we highlight the promising potential of targeting selenoproteins and the biogenesis of selenocysteine as avenues for therapeutic intervention in cancer. By understanding the intricate relationship between selenium, selenoproteins, and reactive oxygen species (ROS), insights can be gained to develop therapies that exploit the inherent vulnerabilities of cancer cells.

Spatial Epidemiological Analysis of Keshan Disease in China

Objectives:

Few researchers have studied the national prevalence of Keshan disease (KD) in China using spatial epidemiological methods. This study aimed to provide geographically precise and visualized evidence for the strategies for KD prevention and control.

Methods:

We surveyed and analyzed 237,000 people in 280 out of 328 KD-endemic counties (85.4%) in mainland China using a design of key investigation based on case-searching in 2015–2016. ArcGIS version 9.0 was used for spatial autocorrelation analysis, spatial interpolation analysis and spatial regression analysis.

Results:

Global autocorrelation analysis showed that global clustering of latent Keshan disease (LKD) prevalence was noted (Moran’s I = 0.22, Z = 7.06, and P < 0.0001), no global clustering of chronic Keshan disease (CKD) prevalence (Moran’s I = 0.03, Z = 1.10, and P = 0.27) was observed. Spatial regression analysis showed that LKD prevalence was negatively correlated with per capita disposable income (t = –4.36, P < 0.0001). Local autocorrelation analysis at the county level effectively identified the cluster areas of LKD prevalence in the provinces of Shaanxi, Gansu, Shanxi, Inner Mongolia, and Jilin. The high-high cluster areas should be given priority for precision prevention and control of Keshan disease.

Conclusions:

This spatial epidemiological study revealed that LKD prevention and control should be strengthened in areas with high values of clustering. Our findings provided spatially, geographically precise and visualized evidence for prioritizing KD prevention and control.

Investigation Into Environmental Selenium and Arsenic Levels and Arseniasis Prevalence in an Arsenic-Affected Coal-Burning Area

This study aims to explore whether selenium (Se) concentration correlates with arseniasis in a high-arsenic coal area in the southern Shaanxi Province, China. Herein, an epidemiological investigation was conducted among 100 arsenic (As)-poisoned patients in Ziyang County, an area with high soil As and Se levels. Fifty healthy subjects were selected from areas without endemic As poisoning. The subjects in the high-As coal area were diagnosed with either normal, suspicious, mild, moderate, or severe As poisoning. Local coal, water, soil, corn, and pepper samples, as well as hair, blood, and urine samples of subjects and patients were collected and analyzed for their As and Se contents. The contents of As and Se in coal, soil, corn, pepper, and hair samples from Ziyang County were significantly higher than those in the control area. The As content of hair in Ziyang County positively correlated with As poisoning, whereas the Se content of hair and urine negatively correlated with As poisoning. The Se content in the body was negatively correlated with the degree of As poisoning, indicating that Se may accelerate the metabolism and decumulation of As and antagonize As toxicity.

A Spatial Ecological Study on Hair Selenium Level of Residents in Keshan Disease Endemic and Non-endemic Areas in Heilongjiang Province, China

This study was aimed to provide, by mapping the spatial distribution of hair selenium levels of residents, visualized evidence for assessment of KD elimination from a perspective of selenium nutrition of the residents living in the KD-endemic and non-endemic areas. Using a spatial ecological research design, 401 male permanent residents in KD-endemic and non-endemic areas participated in this study. Demographic information and hair samples were obtained through a questionnaire survey and sample collection, respectively. Hair selenium was measured using hydride generation atomic fluorescence spectrometry. Thematic maps were created, and spatial analysis was conducted using ArcGIS 9.0. The median of hair selenium of the participants was 0.30 (IQR, 0.23-0.34) mg/kg. The median hair selenium of the residents in the KD-endemic areas was significantly lower than that of the residents of the non-endemic areas. The hair selenium levels of residents were spatially clustered, with cold spots and hot spots located in northwest and southwest regions respectively. Residents living in KD-endemic areas may still have selenium deficiency. Measuring hair selenium levels of residents in KD-endemic areas as a molecular marker of selenium nutritional status as part of KD surveillance could provide visualized evidence for the evaluation of KD elimination from a perspective of selenium nutrition of the residents living in the KD endemic areas.

Association of selenium levels with the prevention and control of Keshan disease: A cross-sectional study

PURPOSE

The prevalence of Keshan disease (KD) is low and has reached controlled or eliminated levels even in counties that had a high KD prevalence in the past. Few nationwide surveys on selenium levels in KD areas have been conducted in the past 2 decades. We conducted a cross-sectional study to investigate the selenium levels and their association with KD control and prevention in areas where KD is prevalent.

METHODS

We collected 2143 human-hair, 698 soil, 701 rice, 607 flour, 521 corn, and 330 other-food samples from 49 counties with KD and 19 non-KD counties of nine KD provinces of China. The selenium content of samples was examined with hydride generation atomic fluorescence spectrometry. The difference in selenium levels between the KD and non-KD areas was analyzed. Cochran-Armitage trend tests were used to evaluate the association between selenium levels and KD control.

RESULTS

The selenium levels in human hair, soil, staple foods, and other foods in the KD areas (0.2996 mg/kg, 0.1380 mg/kg, 0.0190 mg/kg and 0.0076 mg/kg, respectively) were lower than those in the non-KD areas (0.3700 mg/kg, 0.1930 mg/kg, 0.0240 mg/kg and 0.0165 mg/kg, respectively). The Cochran-Armitage tests showed that there was a trend for the selenium standard ratio in the counties to increase in the order of KD uncontrolled, to controlled, to eliminated (Z = 2.229, P < 0.05).

CONCLUSION

The residents in the KD areas were found to be selenium-deficient. Improving the supply of staple foods containing selenium levels exceeding 0.025 mg/kg and abundant foodstuffs might contribute to KD control and prevention.

A Spatial Ecological Study on Serum Selenium and Keshan Disease in Heilongjiang Province, China

BACKGROUND

There are no reports on the spatial ecology of serum selenium and Keshan disease in Heilongjiang Province in China.

OBJECTIVE

This study aimed to conduct a spatial assessment of Keshan disease elimination at the level of the etiological molecular marker.

METHODS

An ecological study design was used. The levels of serum selenium of the 571 residents aged between 17 and 35 years and living in rural areas, townships, and cities in 63 Keshan disease endemic counties and 46 non-endemic counties in Heilongjiang Province were measured using atomic fluorescence spectrometry. A spatial analysis of serum selenium levels was conducted.

RESULTS

The median serum selenium level of the 571 participants was 1.00 μmol/L, and that of participants living in Keshan disease endemic areas was 0.97 μmol/L, which was significantly lower compared to the level of those living in non-endemic areas (1.01 μmol/L, P = 0.0037). Serum selenium levels of the participants living in rural areas, townships, and cities were significantly different (P < 0.001) at 0.95 μmol/L, 1.00 μmol/L, and 1.04 μmol/L, respectively. Spatial regression analysis showed that the distribution of serum selenium levels was positively correlated with the per capita gross domestic product.

CONCLUSION

The analysis of the spatial distribution of serum selenium levels provided precise visual evidence that selenium deficiency may still be present among residents of Keshan disease endemic counties of Tangyuan, Mulan, Lingdong, Suiling, and Dongshan. Selenium levels should therefore be included in the national surveillance of Keshan disease.

A spatial study on serum selenoprotein P and Keshan disease in Heilongjiang Province, China

BACKGROUND

Few spatial studies on serum selenoprotein P (SELENOP) and Keshan disease (KD) have been reported at the county-level in Heilongjiang province, China. This study aimed to provide visualized spatial epidemiological evidence of selenium molecular marker in residents living in endemic areas for the precise assessment of prevention, control, and elimination of KD.

METHODS

Using a spatial ecological study design, 587 subjects living in cities, townships, and rural areas of 50 KD endemic counties and 37 non-endemic counties in Heilongjiang province were investigated. The serum SELENOP levels of the participants were measured by enzyme-linked immunosorbent assay. Thematic maps were created, and spatial regression analysis was conducted using ordinary least squares.

RESULTS

The mean serum SELENOP level of the 587 subjects was 7.4 ± 3.0 μg/mL. The mean levels of serum SELENOP were higher in cities (7.4 ± 2.9 μg/mL) and townships (7.9 ± 3.2 μg/mL) than in rural areas (6.0 ± 3.0 μg/mL). The mean levels of serum SELENOP were trending towards high levels in non-endemic areas (7.4 ± 3.0 μg/mL) than in KD endemic areas (6.3 ± 3.3 μg/mL). Spatial regression analysis showed that the serum SELENOP level was positively correlated with the per capita gross domestic product.

CONCLUSION

Selenium deficiency may still exist in some KD endemic counties in Heilongjiang province, including Lingdong, Nenjiang, and Baiquan; these counties should be considered as key areas for precision prevention, control, and elimination of KD. Inclusion of selenium in the national surveillance of KD will provide more evidence for the assessment of KD elimination from a selenium nutrition perspective.

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.

Selenium distribution in the Chinese environment and its relationship with human health: A review

This paper reviewed the Se in the environment (including total Se in soil, water, plants, and food), the daily Se intake and Se content in human hair were also examined to elucidate Se distribution in the environment and its effects on human health in China. Approximately 51% of China is Se deficiency in soil, compared with 72% in the survey conducted in 1989. Low Se concentrations in soil, water, plants, human diet and thus human hair were found in most areas of China. The only significant difference was observed between Se-rich and Se-excessive areas for Se contents in water, staple cereal, vegetables, fruits, and animal-based food, no remarkable contrast was found among other areas (p>0.05). This study also demonstrated that 39-61% of Chinese residents have lower daily Se intakes according to WHO/FAO recommended value (26-34μg/day). Further studies should focus on thoroughly understanding the concentration, speciation, and distribution of Se in the environment and food chain to successfully utilize Se resources, remediate Se deficiency, and assess the Se states and eco-effects on human health.

Serum quantitative proteomic analysis of patients with keshan disease based on iTRAQ labeling technique: A first term study

Keshan disease (KD), an endemic myocardiopathy, with unknown etiology, is still threatening human health. Proteomics studies of Keshan disease is rarely known. In the current study, isobaric tags for relative and absolute quantitation (iTRAQ) labeling coupled with two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) was firstly used to screen for the differentially expressed proteins (DEPs) in serum between Keshan disease and healthy residents in endemic area. 27 differentially expressed proteins were quantified, 9 of which were significantly altered (fold change > 1.2 or < 0.8) between the two groups. Bioinformatic analysis revealed that a wide variety of biology process played roles in KD pathophysiology. These differentially expressed proteins were mainly involved in complement coagulation pathways. A significant high serum level of LGALS3BP were observed. Our first term study in KD proteomics provided new view into the molecular mechanisms of KD disease.

Micronutrients and Leptospirosis: A Review of the Current Evidence

BACKGROUND

Leptospirosis is one of the most widespread zoonoses and represents a major threat to human health. Due to the high burden of disease, limitations in diagnostics, and limited coverage and availability of effective human and veterinary vaccines, leptospirosis remains an important neglected zoonotic disease. Improved surveillance and identification of modifiable risk factors for leptospirosis are urgently needed to inform preventive interventions and reduce the risk and severity of Leptospira infection.

METHODOLOGY/PRINCIPAL FINDINGS

This review was conducted to examine the evidence that links micronutrient status and Leptospira infection. A total of 56 studies were included in this review: 28 in vitro, 17 animal, and 11 observational human studies. Findings indicated that Leptospira infection is associated with higher iron and calcium concentrations and hypomagnesemia.

CONCLUSIONS/SIGNIFICANCE

Few prospective studies and no randomized trials have been conducted to date to examine the potential role of micronutrients in Leptospira infection. The limited literature in this area constrains our ability to make specific recommendations; however, the roles of iron, calcium, and magnesium in leptospirosis represent important areas for future research. The role of micronutrients in leptospirosis risk and severity needs to be elucidated in larger prospective human studies to inform public health interventions.

Effects of selenium-chitosan on blood selenium concentration, antioxidation status, and cellular and humoral immunity in mice

One hundred and eighty Kunming mice were allotted to three groups in a randomized complete block design, including two treatments and one control. Mice in group 1 were fed a basal diet as control, while mice in groups 2 and 3 were fed the basal diet supplemented with 0.2 mg/kg selenium as sodium selenite (SS) or selenium-chitosan (SC), respectively. On day 28 of the experiment, blood selenium concentration, glutathione peroxidase (GPx) activity, plasma superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, and Con A-induced splenocyte proliferation were determined, and plasma interleukin-2 (IL-2) and interferon-γ (IFN-γ) concentrations, splenic plaque-forming cell (PFC) responses, serum hemolysis level (HC50), and delayed-type hypersensitivity (DTH) responses were determined on day 15 of the experiment. The results showed that blood selenium concentration, GPx activity, splenic PFC response, and plasma IL-2 and IFN-γ concentrations in SC group were higher than those in the control and SS groups (P < 0.01 or P < 0.05), respectively. Plasma SOD activity, Serum hemolysis level, DTH responses, and Con A-induced splenocyte proliferation in SC group were higher than those in control (P < 0.01 or P < 0.05). Plasma SOD activity, serum hemolysis level, DTH responses, and Con A-induced splenocyte proliferation in SC group were also higher than those in SS group, while there was no significant difference between SC and SS groups (P > 0.05). Plasma MDA content in SC group was lower than those in the control and SS groups (P < 0.01 or P < 0.05). It is concluded that SC supplement can increase blood selenium concentration, antioxidation status, and cellular and humoral immunity, and SC has better biological activity than SS in mice.

TLR2-ICAM1-Gadd45α axis mediates the epigenetic effect of selenium on DNA methylation and gene expression in Keshan disease

Keshan disease (KD) is a fatal dilated cardiomyopathy with unknown etiology, and selenium deficiency is considered the main cause of KD. Several observations implicate a role for altered DNA methylation in selenium deficiency-related diseases. The aim of the present study was to investigate the epigenetic effects of selenium (Se) on DNA methylation and gene expression in Keshan disease. Using methylated DNA immunoprecipitation chip (MeDIP-Chip) and quantitative RT-PCR, we identified two inflammatory-related genes (TLR2 and ICAM1) that were differentially methylated and expressed between normal individuals and KD patients. Results from DNA methylation profile between KD patients and normal individuals showed that selenium deficiency decreased methylation of CpG islands in promoter regions of TLR2 and ICAM1 and upregulated messenger RNA (mRNA) and protein levels of TLR2 and ICAM1. In rat animal model of Keshan disease, selenite treatment could increase TLR2 and ICAM1 promoter methylation, suppress these genes expression, and reduce infiltration of myocardial inflammatory cells. In cell culture model of Keshan disease, we found 5-Aza-dC (DNMT1 inhibitor) treatment in the presence of selenium-reduced mRNA and protein levels of DNMT1 regardless of TLR2 and ICAM1 promoter methylation status and expression levels of these genes. Selenite treatment suppressed the expression of the Gadd45α, TLR2, and ICAM1 in a concentration-dependent manner, while selenium deficiency increased the expression of the Gadd45α, TLR2, and ICAM1 and decreased TLR2 and ICAM1 promoter methylation level in a time-dependent manner. Our results revealed that TLR2-ICAM1-Gadd45α axis might play an important role in gene-specific active DNA demethylation during inflammatory response in myocardium.

Correlation between oxidative stress and L-type calcium channel expression in the ventricular myocardia of selenium-deficient mice

OBJECTIVE

Expression of the Cacna1c (calcium channel, voltage-dependent, L-type, α1C subunit) gene was studied to investigate the relationship between oxidative stress and L-type calcium channels in the myocardium of selenium-deficient mice.

METHODS

Selenium levels in liver and heart tissue samples from mice fed normal or selenium-deficient diets were evaluated by fluorometry. In the same mice, glutathione peroxidase (GPx) and Cacna1c gene expression were analysed, malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were measured, oxidoreductase gene expression profiles were analysed (by DNA microarray), and myocardial structural changes were studied.

RESULTS

In selenium-deficient versus control mice, GPx expression and SOD activity were decreased, and Cacna1c expression and MDA concentration were increased. Selenoprotein oxidoreductase and nonselenoprotein oxidoreductase gene expression differed significantly between selenium-deficient and control mice. In selenium-deficient mice, myocardial fibres were separated by loose collagenous tissue; electron microscopy showed shortened sarcomeres, dilated sarcoplasmic reticulum, scattered myofibril lysis and increased mitochondria with amorphous matrix densities.

CONCLUSION

L-type calcium channels were involved in selenium deficiency-induced cardiomyocyte injury, which was positively related to oxidative stress.