Effect of high-dose sodium selenite in cardiac surgery patients: A randomized controlled bi-center trial

The effect of high-dose selenium on mortality and postoperative organ dysfunction in post-cardiotomy cardiogenic shock patients supported with mechanical circulatory support - A post-hoc analysis of the SUSTAIN CSX trial

PURPOSE

Cardiac surgery, post-cardiotomy cardiogenic shock (PCCS), and temporary mechanical circulatory support (tMCS) provoke substantial inflammation. We therefore investigated whether a selenium-based, anti-inflammatory strategy would benefit PCCS patients treated with tMCS in a post-hoc analysis of the sustain CSX trial.

METHODS

Post-hoc analysis of patients receiving tMCS for PCCS in the Sustain CSX trial, which investigated the effects of high-dose selenium on postoperative organ dysfunction in cardiac surgery patients.

PRIMARY OUTCOME

duration of tMCS therapy.

SECONDARY OUTCOMES

postoperative organ dysfunction and 30-day mortality.

RESULTS

Thirty-nine patients were treated with tMCS for PCCS. There was no difference in the median duration of tMCS between the selenium and the placebo group (3 days [IQR: 1-6] vs. 2 days [IQR: 1-7], p = 0.52). Median dialysis duration was longer in the selenium group (1.5 days [0-21.8] vs. 0 days [0-1.8], p = 0.048). There was no difference in 30-day mortality (53% vs. 41%, OR 1.44, 95% CI 0.32-6.47, p = 0.62).

CONCLUSION

In this explorative study, a perioperative high-dose selenium-supplementation did not show beneficial effects on organ dysfunctions and mortality rates in patients with PCCS receiving tMCS.

A wide scope, pan-comparative, systematic meta-analysis of the efficacy of prophylactic strategies for cardiac surgery-associated acute kidney injury

Acute kidney injury (AKI) is the most common complication of cardiac surgery. Cardiac surgery-associated AKI (CSA-AKI) is caused by systemic and renal hemodynamic impairment and parenchymal injury. Prophylaxis of CSA-AKI remains an unmet priority, for which preventive strategies based on drug therapies, hydration procedures, and remote ischemic preconditioning (RIPC) have been tested in pre-clinical and clinical studies, with variable success. Contradicting reports and scarce or insufficiently pondered information have blurred conclusions. Therefore, with an aim to contribute to consolidating the available information, we carried out a wide scope, pan-comparative meta-analysis including the accessible information about the most relevant nephroprotective approaches assayed. After a thorough examination of 1892 documents retrieved from PubMed and Web of Science, 150 studies were used for the meta-analysis. Individual odds ratios of efficacy at reducing AKI incidence, need for dialysis, and plasma creatinine elevation were obtained for each alleged protectant. Also, the combined class effect of drug families and protective strategies was also meta-analyzed. Our results show that no drug family or procedure affords substantial protection against CSA-AKI. Only, a mild but significant reduction in the incidence of CSA-AKI by preemptive treatment with dopaminergic and adrenergic drugs, vasodilators, and the RIPC technique. The integrated analysis suggests that single-drug approaches are unlikely to cope with the variety of individual pathophysiological scenarios potentially underlying CSA-AKI. Accordingly, a theragnostic approach involving the etiopathological diagnosis of kidney frailty is necessary to guide research towards the development of pharmacological combinations concomitantly and effectively addressing the key mechanisms of CSA-AKI.

Selenium as a Modulator of Redox Reactions in the Prevention and Treatment of Cardiovascular Diseases

Cardiovascular diseases stand as the predominant global cause of mortality, exerting a profound impact on both life expectancy and its quality. Given their immense public health burden, extensive efforts have been dedicated to comprehending the underlying mechanisms and developing strategies for prevention and treatment. Selenium, a crucial participant in redox reactions, emerges as a notable factor in maintaining myocardial cell homeostasis and influencing the progression of cardiovascular disorders. Some disorders, such as Keshan disease, are directly linked with its environmental deficiency. Nevertheless, the precise extent of its impact on the cardiovascular system remains unclear, marked by contradictory findings in the existing literature. High selenium levels have been associated with an increased risk of developing hypertension, while lower concentrations have been linked to heart failure and atrial fibrillation. Although some trials have shown its potential effectiveness in specific groups of patients, large cohort supplementation attempts have generally yielded unsatisfactory outcomes. Consequently, there persists a significant need for further research aimed at delineating specific patient cohorts and groups of diseases that would benefit from selenium supplementation.

Selenite selectively kills lung fibroblasts to treat bleomycin-induced pulmonary fibrosis

BACKGROUND

Interstitial lung disease (ILD) treatment is a critical unmet need. Selenium is an essential trace element for human life and an antioxidant that activates glutathione, but the gap between its necessity and its toxicity is small and requires special attention. Whether selenium can be used in the treatment of ILD remains unclear.

METHODS

We investigated the prophylactic and therapeutic effects of selenite, a selenium derivative, in ILD using a murine model of bleomycin-induced idiopathic pulmonary fibrosis (IPF). We further elucidated the underlying mechanism using in vitro cell models and examined their relevance in human tissue specimens. The therapeutic effect of selenite in bleomycin-administered mice was assessed by respiratory function and histochemical changes. Selenite-induced apoptosis and reactive oxygen species (ROS) production in murine lung fibroblasts were measured.

RESULTS

Selenite, administered 1 day (inflammation phase) or 8 days (fibrotic phase) after bleomycin, prevented and treated deterioration of lung function and pulmonary fibrosis in mice. Mechanistically, selenite inhibited the proliferation and induced apoptosis of murine lung fibroblasts after bleomycin treatment both in vitro and in vivo. In addition, selenite upregulated glutathione reductase (GR) and thioredoxin reductase (TrxR) in murine lung fibroblasts, but not in lung epithelial cells, upon bleomycin treatment. GR and TrxR inhibition eliminates the therapeutic effects of selenite. Furthermore, we found that GR and TrxR were upregulated in the human lung fibroblasts of IPF patient samples.

CONCLUSIONS

Selenite induces ROS production and apoptosis in murine lung fibroblasts through GR and TrxR upregulation, thereby providing a therapeutic effect in bleomycin-induced IPF.

LLL 44-4 : Micronutrients in acute disease and critical illness

Micronutrients (MN), i.e. trace elements and vitamins, are essential components of the diet in relatively small amounts in any form of nutrition, with special needs in critically ill patients. Critical illness is characterised by the presence of inflammation and oxidative stress. MNs are tightly involved in antioxidant and immune defences. In addition, some conditions, and treatments result in large losses of biological fluids containing MNs: therefore, acute renal injury requiring renal replacement therapy, acute intestinal failure, and major burns and trauma are at high risk of acute depletion of body stores, and of deficiency. MN requirements are increased above standard DRI. Blood level interpretation is complicated by inflammation: some biomarkers assist the status determination. Due to the acute challenges of critical illness, it of utmost importance to cover the needs to maintain the organism's endogenous immune and antioxidant defences, and capacity to repair tissues. Practical strategies are proposed.

Procalcitonin for the diagnosis of postoperative bacterial infection after adult cardiac surgery: a systematic review and meta-analysis

BACKGROUND AND AIMS

Patients undergoing cardiac surgery are subject to infectious complications that adversely affect outcomes. Rapid identification is essential for adequate treatment. Procalcitonin (PCT) is a noninvasive blood test that could serve this purpose, however its validity in the cardiac surgery population is still debated. We therefore performed a systematic review and meta-analysis to estimate the accuracy of PCT for the diagnosis of postoperative bacterial infection after cardiac surgery.

METHODS

We included studies on adult cardiac surgery patients, providing estimates of test accuracy. Search was performed on PubMed, EmBase and WebOfScience on April 12th, 2023 and rerun on September 15th, 2023, limited to the last 10 years. Study quality was assessed with the QUADAS-2 tool. The pooled measures of performance and diagnostic accuracy, and corresponding 95% Confidence Intervals (CI), were calculated using a bivariate regression model. Due to the variation in reported thresholds, we used a multiple-thresholds within a study random effects model for meta-analysis (diagmeta R-package).

RESULTS

Eleven studies were included in the systematic review, and 10 (2984 patients) in the meta-analysis. All studies were single-center with observational design, five of which with retrospective data collection. Quality assessment highlighted various issues, mainly concerning lack of prespecified thresholds for the index test in all studies. Results of bivariate model analysis using multiple thresholds within a study identified the optimal threshold at 3 ng/mL, with a mean sensitivity of 0.67 (0.47-0.82), mean specificity of 0.73 (95% CI 0.65-0.79), and AUC of 0.75 (IC95% 0.29-0.95). Given its importance for practice, we also evaluated PCT's predictive capability. We found that positive predictive value is at most close to 50%, also with a high prevalence (30%), and the negative predictive value was always > 90% when prevalence was < 20%.

CONCLUSIONS

These results suggest that PCT may be used to help rule out infection after cardiac surgery. The optimal threshold of 3 ng/mL identified in this work should be confirmed with large, well-designed randomized trials that evaluate the test's impact on health outcomes and on the use of antibiotic therapy. PROSPERO Registration number CRD42023415773. Registered 22 April 2023.

Dynamic changes of serum trace elements following cardiac surgery: A systematic review and meta-analysis

BACKGROUND

Cardiac surgeries are known to induce an inflammatory response. Besides, dietary factors such as trace elements contribute to promoting cardiovascular health by maintaining oxidative balance. Here we systematically review the literature about alterations in serum concentrations of zinc (Zn), copper (Cu), and selenium (Se) in response to cardiac surgeries.

METHODS

A systematic search was performed on databases until the end of December 2022. Studies assessing the changes of mentioned elements in adult patients undergoing cardiac surgery were included. Changes in the means and standard deviations of the elements before and after the cardiac surgery were utilized as desired effect sizes.

RESULTS

Among 1252 records found in the primary search, 23 and 21 articles were included in the systematic review and meta-analysis respectively. Seventeen studies evaluated the changes in serum Zn and Cu levels, and fifteen studies assessed Se levels. According to the results of quantitative analysis, Zn, Cu, and Se concentrations, one day after the surgery were significantly lower than preoperative values (WMD for Zn: 4.64 µmol/L [3.57-5.72], WMD for Cu: 1.62 µmol/L [0.52-2.72], and WMD for Se: 0.1 µmol/L [0.03-0.16]). The concentration of trace elements recovered gradually during the first-week post-operation and reached preoperative levels or even higher.

CONCLUSION

Serum trace elements dropped significantly soon after the cardiac surgery, but they reached their baseline levels mostly during the first week after the surgery. Future studies are warranted to elucidate the impact of alterations in serum concentration of trace elements on the outcomes and complications of open-heart surgeries.

Efficacy and safety of selenium or vitamin E administration alone or in combination in ICU patients: A systematic review and meta-analysis

BACKGROUND

Micronutrient administration that contributes to antioxidant defense has been extensively studied in critically ill patients, but consensus remains elusive. Selenium and vitamin E are two important micronutrients that have synergistic antioxidant effects. This meta-analysis aimed to assess the effect of selenium or vitamin E administration alone and the combination of both on clinical outcomes in patients hospitalized in the ICU.

METHODS

After electronic searches on PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), SinoMed, VIP database and Wanfang data, initially 1767 papers were found, and 30 interventional studies were included in this analysis. We assessed the risk-difference between treatment and control (standard treatment) groups by pooling available data on length of stay (ICU length of stay and hospital length of stay), mortality (ICU mortality, hospital mortality, 28-day mortality, 6-month mortality and all-cause mortality), duration of mechanical ventilation, adverse events and new infections.

RESULTS

By analyzing the included studies, we found no significant effect of selenium administration alone on mortality, mechanical ventilation duration, or adverse events in ICU patients. However, after excluding studies with high heterogeneity, the meta-analysis showed that selenium alone reduced the length of hospital stay (MD: -1.38; 95% CI: -2.52, -0.23; I-square: 0%). Vitamin E administration alone had no significant effect on mortality, duration of mechanical ventilation, or adverse events in ICU patients. However, after excluding studies with high heterogeneity, the meta-analysis showed that vitamin E alone could reduce the length of ICU stay (MD: -1.27; 95% CI: -1.86, -0.67; I-square: 16%). Combined administration of selenium and vitamin E had no significant effect on primary outcomes in ICU patients.

CONCLUSIONS

Selenium administration alone may shorten the length of hospital stay, while vitamin E alone may reduce the length of ICU stay. The putative synergistic beneficial effect of combined administration of selenium and vitamin E in ICU patients has not been observed, but more clinical studies are pending to confirm it further.

Perioperative selenium administration in cardiac surgery patients, a way out to reduce post surgical adversities? A meta analysis

Introduction

The oxidative damage suffered in cardiac surgery is associated with declining trace elements which lead to the development of multi organ dysfunction (MOD), acute kidney injury (AKI), or increased length of hospital stay (LOS). Recent evidence shows the cardioprotective role of the trace element selenium as it mitigates worsening outcomes post cardiac surgery. Hence, this meta analysis aims to investigate the role of selenium in lowering cardiac surgery related adverse outcomes.

Methods

Literature search of five electronic databases was performed from the inception of the paper till 29th July, 2023. Eligibility criteria included; (a) randomized clinical trials with Adult patients (≥18 years) undergoing cardiac surgery (b) intervention with selenium pre or/and postoperatively; (c) a control group of a placebo, normal saline, or no selenium. Outcomes of interest include postoperative mortality, LOS in the hospital and Intensive Care Unit (ICU), AKI, troponin I, and Creatinine Kinase-MB (CK-MB). The Cochrane bias assessment tool was used to evaluate the risk of bias. Outcomes were pooled with the Mantel-Haenszel Random-effects model using Review Manager.

Results

Seven RCTs with 2,521 patients and 65% of males were included in this paper. No noticable differences were observed between selenium and control groups in terms of postoperative AKI, mortality, LOS in hospital and ICU, troponin I, and CK-MB levels. All studies had a low risk of bias on quality assessment.

Discussion

Our meta analysis demonstrated no discernible effects of selenium infusion on post operative complications among patients undergoing cardiac surgery. Further large scale multi centered studies comparing the protective role of selenium with combined therapy of other bioactive agents are needed to provide convincing explanations.

Systematic Review Registration

PROSPERO Identifier: 424920.

Effect of High-Dose Selenium on Postoperative Organ Dysfunction and Mortality in Cardiac Surgery Patients: The SUSTAIN CSX Randomized Clinical Trial

Importance

Selenium contributes to antioxidative, anti-inflammatory, and immunomodulatory pathways, which may improve outcomes in patients at high risk of organ dysfunctions after cardiac surgery.

Objective

To assess the ability of high-dose intravenous sodium selenite treatment to reduce postoperative organ dysfunction and mortality in cardiac surgery patients.

Design, Setting, and Participants

This multicenter, randomized, double-blind, placebo-controlled trial took place at 23 sites in Germany and Canada from January 2015 to January 2021. Adult cardiac surgery patients with a European System for Cardiac Operative Risk Evaluation II score-predicted mortality of 5% or more or planned combined surgical procedures were randomized.

Interventions

Patients were randomly assigned (1:1) by a web-based system to receive either perioperative intravenous high-dose selenium supplementation of 2000 μg/L of sodium selenite prior to cardiopulmonary bypass, 2000 μg/L immediately postoperatively, and 1000 μg/L each day in intensive care for a maximum of 10 days or placebo.

Main Outcomes and Measures

The primary end point was a composite of the numbers of days alive and free from organ dysfunction during the first 30 days following cardiac surgery.

Results

A total of 1416 adult cardiac surgery patients were analyzed (mean [SD] age, 68.2 [10.4] years; 1043 [74.8%] male). The median (IQR) predicted 30-day mortality by European System for Cardiac Operative Risk Evaluation II score was 8.7% (5.6%-14.9%), and most patients had combined coronary revascularization and valvular procedures. Selenium did not increase the number of persistent organ dysfunction-free and alive days over the first 30 postoperative days (median [IQR], 29 [28-30] vs 29 [28-30]; P = .45). The 30-day mortality rates were 4.2% in the selenium and 5.0% in the placebo group (odds ratio, 0.82; 95% CI, 0.50-1.36; P = .44). Safety outcomes did not differ between the groups.

Conclusions and Relevance

In high-risk cardiac surgery patients, perioperative administration of high-dose intravenous sodium selenite did not reduce morbidity or mortality. The present data do not support the routine perioperative use of selenium for patients undergoing cardiac surgery.

Trial Registration

ClinicalTrials.gov Identifier: NCT02002247.

The effect of selenium therapy in critically ill patients: an umbrella review of systematic reviews and meta-analysis of randomized controlled trials

BACKGROUND

Selenium is an essential nutrient with antioxidant, anti-inflammatory, and immuno-regulatory properties. Studies have displayed that in critically ill patients, selenium supplementation may be a potentially promising adjunctive therapy.

OBJECTIVE

We aimed to present an overview of the effects of selenium supplementation in adult critically ill patients based on published systematic reviews and meta-analyses (SRMAs) of randomized controlled trials (RCTs).

METHODS

A literature search in three electronic databases, PubMed, Scopus, and Web of Science, was performed to find eligible SRMAs until July 2022. For each outcome, the risk ratios (RRs) or mean differences (MDs) and 95% confidence intervals (CIs) were recalculated using either random or fixed effect models. The methodological quality and quality of evidence of the SRMAs were assessed by applying "A Measurement Tool to Assess Systematic Reviews" (AMSTAR2) and Grading of Recommendations Assessment, Development, and Evaluation(GRADE) tools, respectively.

RESULTS

We included 17 meta-analyses containing 24 RCTs based on inclusion criteria. Selenium supplementation can reduce the incidence of mortality (RR: 0.83, 95% CI 0.71, 0.98, P = 0.024) and incidence of acute renal failure (RR: 0.67, 95% CI 0.46, 0.98, P: 0.038) significantly; however, the certainty of evidence was low. Moreover, with moderate to very low certainty of evidence, no significant effects were found for risk of infection (RR: 0.92, 95% CI 0.80, 1.05, P: 0.207), pneumonia (RR: 1.11, 95% CI 0.72, 1.72, P: 0.675), as well as the length of ICU (MD: 0.15, 95% CI - 1.75, 2.05, P: 0.876) and hospital stay (MD: - 0.51, 95% CI - 3.74, 2.72, P: 0.757) and days on ventilation (MD: - 0.98, 95% CI - 2.93, 0.98, P: 0.329).

CONCLUSIONS

With low quality of evidence, the use of selenium supplementation could improve the risk of mortality and acute renal failure, but not other outcomes in critically ill patients.

Peri-operative nutrition in cardiovascular surgery: current pitfalls and future directions

In the field of cardiovascular surgery, many areas are frequently evaluated to improve patient outcomes. Even though cardiac surgery has advanced significantly, peri-operative nutrition remains an area needing special attention and is under-considered in patient results. The three portions of cardiac surgical nutrition optimization are pre-operative, intra-operative and post-operative. All these, merit important clinical intervention which when done properly can significantly improve patient recovery and reduce morbidity and mortality. Here we provide a narrative review and recommendations for peri-operative nutritional optimization in cardiac surgery.

High dose supplementation of selenium in left ventricular assist device implant surgery - a double-blinded, randomized controlled, pilot trial

BACKGROUND

Systemic inflammation and oxidative stress remain the main cause of complications in heart failure patients receiving a left ventricular assist device (LVAD). Selenoproteins are a cornerstone of antioxidant defense mechanisms for improving inflammatory conditions.

METHODS

We conducted a monocentric double-blinded, randomized pilot trial. Patients scheduled for LVAD implantation were randomized to receive 300μg of selenium the evening before surgery orally, followed by high-dose intravenous selenium supplementation (3000μg after anesthesia induction, 1000 μg upon intensive care unit (ICU) admission, and 1000μg daily at ICU for a maximum of 14 days), or placebo. The main outcomes of this pilot study were feasibility and effectiveness in restoring serum selenium concentrations.

RESULTS

20 out of 21 randomized patients were included in the analysis. The average recruitment rate was 1.5 patients/month (0-3). The average duration of study intervention was 12.6 days (7-14) with a 97.7% dose compliance. No patient received open-label selenium. The supplementation strategy was effective in compensating low serum selenium concentration (before surgery: control: 63.5±11.9μg/L vs. intervention: 65.8±16.5μg/L, ICU admission: control: 49.0±9.8μg/L vs. intervention: 144.2±45.4μg/L). Comparing to the control group, the serum selenium concentrations in the intervention group were significantly higher during the observation period (baseline: mean of placebo (MoP):63.1 vs. mean of selenium (MoS):64.0; ICU admission: MoP:49.0 vs. MoS:144.6; day 1:MoP:44.9 vs. MoS: 102.4; day 3: MoP:43.6 vs. MoS:100.4; day 5: MoP:48.5 vs. MoS:114.7; day 7: MoP:44.4 vs.MoS:118.3; day 13:MoP:48.0 vs. MoS:131.0).

CONCLUSIONS

Selenium supplementation in patients receiving LVAD-implantation is feasible and effective to compensate a selenium deficiency. This article is protected by copyright. All rights reserved.

Clinical Significance of Micronutrient Supplementation in Critically Ill COVID-19 Patients with Severe ARDS

The interplay between inflammation and oxidative stress is a vicious circle, potentially resulting in organ damage. Essential micronutrients such as selenium (Se) and zinc (Zn) support anti-oxidative defense systems and are commonly depleted in severe disease. This single-center retrospective study investigated micronutrient levels under Se and Zn supplementation in critically ill patients with COVID-19 induced acute respiratory distress syndrome (ARDS) and explored potential relationships with immunological and clinical parameters. According to intensive care unit (ICU) standard operating procedures, patients received 1.0 mg of intravenous Se daily on top of artificial nutrition, which contained various amounts of Se and Zn. Micronutrients, inflammatory cytokines, lymphocyte subsets and clinical data were extracted from the patient data management system on admission and after 10 to 14 days of treatment. Forty-six patients were screened for eligibility and 22 patients were included in the study. Twenty-one patients (95%) suffered from severe ARDS and 14 patients (64%) survived to ICU discharge. On admission, the majority of patients had low Se status biomarkers and Zn levels, along with elevated inflammatory parameters. Se supplementation significantly elevated Se (p = 0.027) and selenoprotein P levels (SELENOP; p = 0.016) to normal range. Accordingly, glutathione peroxidase 3 (GPx3) activity increased over time (p = 0.021). Se biomarkers, most notably SELENOP, were inversely correlated with CRP (r_s = −0.495), PCT (r_s = −0.413), IL-6 (r_s = −0.429), IL-1β (r_s = −0.440) and IL-10 (r_s = −0.461). Positive associations were found for CD8⁺ T cells (r_s = 0.636), NK cells (r_s = 0.772), total IgG (r_s = 0.493) and PaO₂/FiO₂ ratios (r_s = 0.504). In addition, survivors tended to have higher Se levels after 10 to 14 days compared to non-survivors (p = 0.075). Sufficient Se and Zn levels may potentially be of clinical significance for an adequate immune response in critically ill patients with severe COVID-19 ARDS.

Micronutrients early in critical illness, selective or generous, enteral or intravenous?

PURPOSE OF REVIEW

Micronutrients have essential antioxidant and immune functions, while low blood concentrations are frequently observed in critically ill patients. This has led to the concepts of complementation, repletion, or even pharmacological supplementation. Over the last three decades, many clinical studies have tested the latter strategy, with controversial or negative results. Therefore, this review aims at evaluating micronutrient-related interventions that are mandatory or need to be assessed in future trials or clinical registries in all or specific critically ill patients.

RECENT FINDINGS

In the critically ill, low plasma/serum micronutrient levels not always reflect a true deficiency in the absence of demonstrable losses. Current practices of micronutrient provision and monitoring in critical care, vary substantially across the world. Also, recent clinical trials testing high dose as monotherapy (selenium, thiamine, vitamin C, vitamin D) or in combination have failed to demonstrate clinical benefits in sepsis. However, these studies have not applied a physiological integrative approach of micronutrient action.

SUMMARY

Micronutrients are essential in nutrition but their administration and monitoring are difficult. So far, different well designed RCTs on intravenous and oral high dose micronutrient supplementation have been conducted. Nevertheless, very high-dose single micronutrients cannot be advocated at this stage in sepsis, or any other critical condition. By contrast, studies using combination of moderate doses of micronutrients in specific diseases, such as burns and trauma have been associated with improved outcomes. Intravenous administration seems to be the most efficient route. Future clinical trials need to integrate the physiology underlying the interconnected micronutrient activity, and choose more specific primary and secondary endpoints.

Daily parenteral selenium therapy in critically ill patients: An updated systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Patients hospitalized at the intensive care unit (ICU) are more prone to oxidative stress. Antioxidants such as selenium (Se) may have beneficial effects on outcomes in these patients. Studies and systematic reviews in this field have inconclusive results.

METHODS

An updated systematic search was done to find clinical trials published in PubMed, Cochrane's library, ISI web of Science, Scopus, and Ovid databases from January 1980 up to April 2020, to assess the effects of daily Se supplementation on patient's survival, hospital and ICU stay, duration of mechanical ventilation, infection, acute renal failure (ARF) occurrence and serum creatinine levels.

RESULTS

From 1394 papers found in the first step of the search, after deleting duplicate findings, 24 studies were included in this meta-analysis. Results of the pooled random-effect size analysis of 24 trials showed no remarkable effect of daily parenteral Se administration on patient's hospital and ICU stay, duration of mechanical ventilation, infectious complications, ARF, survival and serum creatinine levels (p > 0.05). The subgroup analysis showed that daily parenteral Se administration (in doses higher than 1000 μg/d) increased the length of ICU stay by 4.48-folds (95%CI: -0.5, 9.46, p = 0.07). Parenteral Se supplementation at the first and following dose of ≤1000 μg reduced the number of ARF at the hospitalized patients by 76% and 45%, respectively (p = 0.02, and p = 0.05).

CONCLUSIONS

High doses of Se increases days of ICU stay, but low doses decreases the number of ARF occurrence in ICU patients. More trials are needed to assess its effect on ARF occurrence.

Transferrin improved the generation of cardiomyocyte from human pluripotent stem cells for myocardial infarction repair

Human pluripotent stem cell (hPSC)-derived cardiomyocytes (CMs) hold great promise for the repair of the injured heart, but optimal cell production in a fully chemically defined and cost-effective system is essential for the efficacy and safety of cell transplantation therapies. In this study, we provided a simple and efficient strategy for cardiac differentiation from hPSCs and performed functional evaluation in a rat model of myocardial infarction. Using a chemically defined medium including four components, recombinant human albumin, ascorbic acid, human transferrin, and RPMI 1640, we developed a manageable and cost-effective protocol for robust generation of CMs from hPSCs. Interestingly, the addition of transferrin helped hPSCs to transit from TeSR-E8 medium to the simple cardiac differentiation medium and successfully initiated mesoderm differentiation without significant cell death. The CM generation efficiency was up to 85% based on cTnT expression. We performed transcriptome profiling from differentiation day 0 to 35, and characterized interesting dynamic change of cardiac genes. CMs derived from transferrin-supplemented simple medium have similar transcriptome and the maturation level compared to those generated in B27 minus insulin medium as well as their in vivo counterparts. Importantly, after transplantation, hPSC-derived CMs survived in the infarcted rat heart, significantly improved the physiological function and reduced fibrosis. Our study offers an easy-to-use and cost-effective method for cardiac differentiation and facilitates the translational application of hPSC-derived CMs for heart repair.

Selenium and hydrogen selenide: essential micronutrient and the fourth gasotransmitter?

Selenium (Se) is an essential micronutrient required by organisms of diverse lineage. Dietary Se is converted to hydrogen selenide either enzymatically or by endogenous antioxidant proteins. This convergent biochemical step crucially underlies the subsequent biological activity of Se and argues for inclusion of hydrogen selenide as the fourth endogenous gasotransmitter alongside nitric oxide, carbon monoxide and hydrogen sulfide.Endogenously generated hydrogen selenide is incorporated into numerous 'selenoprotein' oxidoreductase enzymes, essential for maintaining redox-status homeostasis in health and disease. Direct effects of endogenous hydrogen selenide on cellular and molecular targets are currently unknown. Given exogenously, hydrogen selenide acts as a modulator of metabolism via transient inhibition of mitochondrial cytochrome C oxidase. Here we provide an overview of Se biology, its impact on several physiological systems (immune, endocrine, cardiovascular and metabolic) and its utility as a supplement in acute and critical illness states. We further explore the evidence base supporting its role as the fourth gasotransmitter and propose a strategic case towards generation of novel selenomimetic therapeutics.

Pharmacokinetics of Selenium in Healthy Piglets After Different Routes of Administration: Application of Pharmacokinetic Data to the Risk Assessment of Selenium

Selenium (Se) is a trace element in the environment. Although it is a necessary trace element for human and animal health, excessive Se can also pollute the environment and show toxic effects on humans and animals. Since the safe dose range of Se is narrow, it is important to study the pharmacokinetics of Se in order to make better use of the biological effects of Se. In the present study, we investigated the pharmacokinetic process of sodium selenate in healthy piglet plasma after either intramuscular injection or oral administrations, and examined dynamic changes of antioxidant system in healthy piglets after Se supplementation. The results showed that the Se reached the peak concentration of (0.2451 ± 0.0123) μg mL^-1 at (0.4237 ± 0.0185) h following intramuscular injection administration and (0.1781 ± 0.0142) μg mL^-1 at (2.1517 ± 0.1806) h following oral administration in the plasma. The average AUC of sodium selenite following intramuscular injection and oral administrations was (31.7260 ± 1.3574) and (75.1460 ± 3.4127) mg L^-1 h^-1, respectively. Total antioxidant capacity (T-AOC), glutathione peroxidase (GPx), and superoxide dismutase (SOD) generally show an upward trend and malondialdehyde (MDA) shows a downward trend, regardless of intramuscular injection or oral sodium selenite. An increased concentration of Se was observed in the serum of healthy piglets after intramuscular injection and oral sodium selenite. Our results indicated that the pharmacokinetic process of sodium selenate in healthy piglet blood conforms to the two-chamber open model. Its pharmacokinetic properties are rapid absorption and slow excretion. Antioxidant systems in healthy piglets vary with Se levels, but there is a significant lag period compared with the latter. Our current findings will provide a more complete understanding of clinical rational Se supplementation and avoid contamination of the environment by overdose.

Selenium in Cardiac Surgery

Selenium (Se) is an essential trace element that plays a pivotal role in many of the body's regulatory and metabolic functions, especially during times of stress. After uptake, Se is incorporated into several Se-dependent proteins, which have potent anti-inflammatory and antioxidant capacities. Several observational clinical studies have demonstrated that Se deficiency can cause chronic cardiovascular diseases and aggravate organ dysfunction after cardiac surgery and that low levels of Se may be independently associated with the development of organ dysfunction after cardiac surgery. Based on these findings, several studies have investigated the effects of a perioperative Se supplementation strategy. Therefore, the present review describes in depth the pathophysiology and harmful stimuli during cardiac surgery, how Se may counteract these injuries, the different types of Se supplementation strategies that have been evaluated, and current evidence of its clinical significance.

Current Evidence about Nutrition Support in Cardiac Surgery Patients-What Do We Know?

Nutrition support is increasingly recognized as a clinically relevant aspect of the intensive care treatment of cardiac surgery patients. However, evidence from adequate large-scale studies evaluating its clinical significance for patients&rsquo; mid- to long-term outcome remains sparse. Considering nutrition support as a key component in the perioperative treatment of these critically ill patients led us to review and discuss our understanding of the metabolic response to the inflammatory burst induced by cardiac surgery. In addition, we discuss how to identify patients who may benefit from nutrition therapy, when to start nutritional interventions, present evidence about the use of enteral and parenteral nutrition and the potential role of pharmaconutrition in cardiac surgery patients. Although the clinical setting of cardiac surgery provides advantages due to its scheduled insult and predictable inflammatory response, researchers and clinicians face lack of evidence and several limitations in the clinical routine, which are critically considered and discussed in this paper.