Study on the performance enhancing effect of rare earth elements in growing and fattening pigs

Associations of maternal urinary rare earth elements individually and in mixtures with neonatal size at birth

Prenatal rare earth elements (REEs) exposure is linked to unfavorable health consequences. Epidemiologic research on repeated measurements of REEs during gestation correlated with fetal growth is exiguous. Until now, few studies have characterized exposure characteristics of REEs in pregnant women. We aimed to ascertain the characteristics and predictors of REEs exposure over three trimesters among pregnant women and examine the possible effects of prenatal REEs exposure on size at birth. Urinary REEs concentrations exhibited considerable within-subject variation with intraclass correlation coefficients ranging from 0.16 to 0.58. Maternal age, household income, gestational weight gain, passive smoking during pregnancy, parity, and neonatal gender were associated with maternal urinary REEs concentrations. Elevated maternal urinary holmium and thulium concentrations in the 3rd trimester were significantly related to reductions in birth weight. Weighted quantile sum (WQS) regression model identified that urinary REEs mixture in the 3rd trimester were negatively related to birth weight (WQSREEs β = -26.22; 95% confidence interval [CI]: -47.62, -4.82), with holmium (40%) and thulium (24%) receiving the highest weights. Male infants received the most weight (>50%) related to decreased birth weight. This study revealed a significant association between individual and mixture REE exposure in late pregnancy with a reduction in birth weight.

Rare Earths-The Answer to Everything

Rare earths, scandium, yttrium, and the fifteen lanthanoids from lanthanum to lutetium, are classified as critical metals because of their ubiquity in daily life. They are present in magnets in cars, especially electric cars; green electricity generating systems and computers; in steel manufacturing; in glass and light emission materials especially for safety lighting and lasers; in exhaust emission catalysts and supports; catalysts in artificial rubber production; in agriculture and animal husbandry; in health and especially cancer diagnosis and treatment; and in a variety of materials and electronic products essential to modern living. They have the potential to replace toxic chromates for corrosion inhibition, in magnetic refrigeration, a variety of new materials, and their role in agriculture may expand. This review examines their role in sustainability, the environment, recycling, corrosion inhibition, crop production, animal feedstocks, catalysis, health, and materials, as well as considering future uses.

Mechanical properties, corrosion and degradation behaviors, and in vitro cytocompatibility of a biodegradable Zn-5La alloy for bone-implant applications

Zinc (Zn) and its alloys are used in bone-fixation devices as biodegradable bone-implant materials due to their good biosafety, biological function, biodegradability, and formability. Unfortunately, the clinical application of pure Zn is hindered by its insufficient mechanical properties and slow degradation rate. In this study, a Zn-5 wt.% lanthanum (Zn-5La) alloy with enhanced mechanical properties, suitable degradation rate, and cytocompatibility was developed through La alloying and hot extrusion. The hot-extruded (HE) Zn-5La alloy showed ultimate tensile strength of 286.3 MPa, tensile yield strength of 139.7 MPa, elongation of 35.7%, compressive yield strength of 262.7 MPa, and microhardness of 109.7 HV. The corrosion resistance of the HE Zn-5La in Hanks' and Dulbecco's modified Eagle medium (DMEM) solutions gradually increased with prolonged immersion time. Further, the HE Zn-5La exhibited an electrochemical corrosion rate of 36.7 μm/y in Hanks' solution and 11.4 μm/y in DMEM solution, and a degradation rate of 49.5 μm/y in Hanks' solution and 30.3 μm/y in DMEM solution, after 30 d of immersion. The corrosion resistance of both HE Zn and Zn-5La in DMEM solution was higher than in Hanks' solution. The 25% concentration extract of the HE Zn-5La showed a cell viability of 106.5%, indicating no cytotoxicity toward MG-63 cells. We recommend the HE Zn-5La alloy as a promising candidate material for biodegradable bone-implant applications. STATEMENT OF SIGNIFICANCE: This work reports the mechanical properties, corrosion and degradation behaviors, in vitro cytocompatibility and antibacterial ability of biodegradable Zn-5La alloy for bone-implant applications. Our findings demonstrate that the hot-extruded (HE) Zn-5La alloy showed an ultimate tensile strength of 286.3 MPa, a yield strength of 139.7 MPa, an elongation of 35.7%, compressive yield strength of 262.7 MPa, and microhardness of 109.7 HV. HE Zn-5La exhibited appropriate degradation rates in Hanks' and DMEM solutions. Furthermore, the HE Zn-5La alloy showed good cytocompatibility toward MG-63 and MC3T3-E1 cells and greater antibacterial ability against S. aureus.

Evaluation of Rare Earth Element-Associated Hormetic Effects in Candidate Fertilizers and Livestock Feed Additives

Rare earth elements (REEs) are recognized as emerging contaminants with implications in human and environmental health. Apart from their adverse effects, REEs have been reported as having positive effects when amended to fertilizers and livestock feed additives, thus suggesting a hormetic trend, implying a concentration-related shift from stimulation to inhibition and toxicity, with analogous trends that have been assessed for a number of xenobiotics. In view of optimizing the success of REE mixtures in stimulating crop yield and/or livestock growth or egg production, one should foresee the comparative concentration-related effects of individual REEs (e.g., Ce and La) vs. their mixtures, which may display distinct trends. The results might prompt further explorations on the use of REE mixtures vs. single REEs aimed at optimizing the preparation of fertilizers and feed additives, in view of the potential recognition of their use in agronomy and zootechny.

The reproductive toxicity of yttrium nitrate in a two-generation study in Sprague-Dawley rats

OBJECTIVE

To evaluate the effects of yttrium nitrate on the development of the parent, offspring and third generation of Sprague-Dawley (SD) rats by using a two-generation reproductive toxicity test.

METHODS

The SD rats were randomly divided into 0 mg/kg group, 10.0 mg/kg group, 30.0 mg/kg group and 90.0 mg/kg group according to the different doses of yttrium nitrate administration. The reproductive toxicity of parent, offspring and third generation SD rats were compared.

RESULTS

The weight gains of F1a female rats and F2a female rats in the low-dose groups were significantly lower than those of the control groups (p < 0.05), the weight gains of F1a male rats in the medium-dose and high-dose groups were significantly lower than those of the control groups (p < 0.05), and the weight gains of F2a male rats in the low-dose, medium-dose and high-dose groups were significantly lower than those of the control groups (p < 0.05). In F0 male rats, the absolute weight and relative weight of the liver in the low-dose, middle-dose, and high-dose groups were significantly lower than those of the control group (p < 0.05). In F1b male rats, the absolute and relative weights of the liver in the medium-dose and high-dose groups were significantly lower than those of the control group (p < 0.05). In F2b male rats, the absolute and relative weights of the liver and spleen of the medium-dose and high-dose groups were significantly lower than those of the control group (p < 0.05). In F2a female rats, the absolute weight and relative weight of oviduct in the high-dose group were significantly lower than those in the control group (p < 0.05). The absolute and relative weights of lung, spleen, brain and uterus of F2b female rats in the high-dose group were higher than those of the control group (p < 0.05). But the pathological test results showed no hepatotoxicity. There was no statistically significant difference in sperm count and sperm motility between male rats in the yttrium nitrate administration groups and the control group (p > 0.05). There was no significant correlation between F0, F1a, F1b, F2a, F2b SD rats' reproductive organ lesions and the dose of yttrium nitrate.

CONCLUSION

Yttrium nitrate at a dose of 90 mg/kg has no reproductive toxicity to two generations of SD rats, but 30.0 mg/kg dose of yttrium nitrate is toxic to the liver weight of male two generations of SD rats, but no hepatotoxicity.

Effects of Dietary Lanthanum Chloride on Growth Performance, Hematology and Serum Biochemistry of Juvenile Clarias gariepinus Catfish Fed Diets Amended with Mixtures of Aflatoxin B1 and Fumonisin B1

This study aimed to determine the effects of dietary lanthanum chloride on the growth and health performance of juvenile Clarias gariepinus when fed diets experimentally contaminated with mixtures of aflatoxin B1 and fumonisin B1. A control diet, (mycotoxin free, diet A), mycotoxin contaminated (diet B), and two mycotoxin-contaminated diets amended with lanthanum chloride (200 mg/kg, diet C; and 400 mg/kg, diet D), were fed to 450 fish divided equally into five groups (each with three replicates) for 56 days. The fish were randomly sampled at the time points: day 7, 28 and day 56 for the zootechnical, hematological and serum biochemical evaluations. The fish fed the diets amended with lanthanum chloride exhibited significantly (p < 0.05) better performance indices compared with the fish fed only the mycotoxin-contaminated diet. Lanthanum chloride elicited significant (p < 0.05) increases in erythrocytes and leucocytes count and significant (p < 0.05) reduction in serum transaminase, alkaline phosphatase, lactate dehydrogenase activities, urea and uric acid concentrations in the fish fed the diets contaminated with mixtures of aflatoxin B1 and fumonisin B1. The study indicates that juvenile Clarias gariepinus may be beneficially cultured with mycotoxin-contaminated grains amended with 200 to 400 mg/kg lanthanum chloride.

Genome-Wide Mutant Screening in Yeast Reveals that the Cell Wall is a First Shield to Discriminate Light From Heavy Lanthanides

The rapidly expanding utilization of lanthanides (Ln) for the development of new technologies, green energies, and agriculture has raised concerns regarding their impacts on the environment and human health. The absence of characterization of the underlying cellular and molecular mechanisms regarding their toxicity is a caveat in the apprehension of their environmental impacts. We performed genomic phenotyping and molecular physiology analyses of Saccharomyces cerevisiae mutants exposed to La and Yb to uncover genes and pathways affecting Ln resistance and toxicity. Ln responses strongly differed from well-known transition metal and from common responses mediated by oxidative compounds. Shared response pathways to La and Yb exposure were associated to lipid metabolism, ion homeostasis, vesicular trafficking, and endocytosis, which represents a putative way of entry for Ln. Cell wall organization and related signaling pathways allowed for the discrimination of light and heavy Ln. Mutants in cell wall integrity-related proteins (e.g., Kre1p, Kre6p) or in the activation of secretory pathway and cell wall proteins (e.g., Kex2p, Kex1p) were resistant to Yb but sensitive to La. Exposure of WT yeast to the serine protease inhibitor tosyl phenylalanyl chloromethyl ketone mimicked the phenotype of kex2∆ under Ln, strengthening these results. Our data also suggest that the relative proportions of chitin and phosphomannan could modulate the proportion of functional groups (phosphates and carboxylates) to which La and Yb could differentially bind. Moreover, we showed that kex2∆, kex1∆, kre1∆, and kre6∆ strains were all sensitive to light Ln (La to Eu), while being increasingly resistant to heavier Ln. Finally, shotgun proteomic analyses identified modulated proteins in kex2∆ exposed to Ln, among which several plasmalemma ion transporters that were less abundant and that could play a role in Yb uptake. By combining these different approaches, we unraveled that cell wall components not only act in Ln adsorption but are also active signal effectors allowing cells to differentiate light and heavy Ln. This work paves the way for future investigations to the better understanding of Ln toxicity in higher eukaryotes.

Combined omics approaches reveal distinct responses between light and heavy rare earth elements in Saccharomyces cerevisiae

The rapid development of green energy sources and new medical technologies contributes to the increased exploitation of rare earth elements (REEs). They can be subdivided into light (LREEs) and heavy (HREEs) REEs. Mining, industrial processing, and end-use practices of REEs has led to elevated environmental concentrations and raises concerns about their toxicity to organisms and their impact on ecosystems. REE toxicity has been reported, but its precise underlying molecular effects have not been well described. Here, transcriptomic and proteomic approaches were combined to decipher the molecular responses of the model organism Saccharomyces cerevisiae to La (LREE) and Yb (HREE). Differences were observed between the early and late responses to La and Yb. Several crucial pathways were modulated in response to both REEs, such as oxidative-reduction processes, DNA replication, and carbohydrate metabolism. REE-specific responses involving the cell wall and pheromone signalling pathways were identified, and these responses have not been reported for other metals. REE exposure also modified the expression and abundance of several ion transport systems, with strong discrepancies between La and Yb. These findings are valuable for prioritizing key genes and proteins involved in La and Yb detoxification mechanisms that deserve further characterization to better understand REE environmental and human health toxicity.

Review of Rare Earth Elements as Fertilizers and Feed Additives: A Knowledge Gap Analysis

Rare earth elements (REEs) are key constituents of modern technology and play important roles in various chemical and industrial applications. They also are increasingly used in agricultural and zootechnical applications, such as fertilizers and feed additives. Early applications of REEs in agriculture have originated in China over the past several decades with the objective of increasing crop productivity and improving livestock yield (e.g., egg production or piglet growth). Outside China, REE agricultural or zootechnical uses are not currently practiced. A number of peer-reviewed manuscripts have evaluated the adverse and the positive effects of some light REEs (lanthanum and cerium salts) or REE mixtures both in plant growth and in livestock yield. This information was never systematically evaluated from the growing body of scientific literature. The present review was designed to evaluate the available evidence for adverse and/or positive effects of REE exposures in plant and animal biota and the cellular/molecular evidence for the REE-associated effects. The overall information points to shifts from toxic to favorable effects in plant systems at lower REE concentrations (possibly suggesting hormesis). The available evidence for REE use as feed additives may suggest positive outcomes at certain doses but requires further investigations before extending this use for zootechnical purposes.

Rare earth elements exposure and the alteration of the hormones in the hypothalamic-pituitary-thyroid (HPT) axis of the residents in an e-waste site: A cross-sectional study

Rare earth elements (REEs) are widely used in electronic products. But the contaminations of REEs in the e-waste sites and the related health effects were barely investigated. In the present study, we analyzed the concentrations of REEs and the hormones of the HPT axis in plasma of subjects recruited from an e-waste area and a reference area in Taizhou, China. The results showed that the concentrations of several REEs like La, Ce were much higher in the exposed group than in the control group (all p < 0.001). The thyroid hormones, FT3 and FT4, and TRH showed no significant difference between the two groups, while the concentration of TSH was significantly higher in the exposed group when compared to the control group (p = 0.002). Separate regression analysis indicated that elevated La and Ce levels were associated with higher TSH concentrations. MDA and 8-iso, the biomarkers of oxidative stress, were also significantly higher in the exposed group than that of the control group (p = 0.002 and p = 0.003, respectively). The increased oxidative stress might be the mechanism underlying the disruptive effects of REEs on TSH. Our results indicated that the quantities of internal exposure of REEs in the subjects in the e-waste area were considerable and the compositional profile of the REEs in the exposed group was different from the control group due to the e-waste dismantling. The expression of TSH were also affected by high La and Ce exposure which showed an endocrine disruption effects of REEs on HPT axis.

Rare earth elements in poplar leaves as indicators of geological environment and technogenesis

Background and anomalous rare earth element (RЕЕ) concentrations in poplar (Populus spp.) leaves in urban areas of Siberia, Russian Far East, and Kazakhstan were determined. Regions with the highest RЕЕ levels were identified. Ratios of light to middle RЕЕs are geochemical indicators of the impacts of oil refining and mining. Airborne dust transport by prevailing winds from ash and slag dumps of power plants and industrial sites, and alluvial terraces control the REE distribution in cities.

Prenatal exposure of rare earth elements cerium and ytterbium and neonatal thyroid stimulating hormone levels: Findings from a birth cohort study

BACKGROUND

Prior studies have suggested exposure to heavy metals and endocrine disrupting chemicals could disturb the homeostasis of thyroid stimulating hormone (TSH), but no epidemiology study concerning the influence of rare earth elements (REE) exposure during pregnancy on neonatal TSH levels. The present study aimed to investigate the relationships between prenatal REE exposure and neonatal TSH levels.

METHODS

A total of 7367 pregnant women were recruited from Wuhan Children's Hospital between September 2012 and October 2014 in Wuhan, China. Urinary concentrations of cerium (Ce), and ytterbium (Yb) were measured by inductively coupled plasma mass spectrometry (ICP-MS). Immunofluorescence assay was used to detect neonatal TSH levels. The associations between REE exposure and neonatal TSH levels were evaluated using multivariate linear regression models.

RESULTS

The geometric means of maternal urinary Ce and Yb concentrations were 0.060 μg/g creatinine and 0.025 μg/g creatinine, respectively. The results showed that per doubling of maternal urinary Ce and Yb were associated with 4.07% (95% CI: -5.80%, -2.31%), 5.13% (95% CI: -6.93%, -3.30%) decreased neonatal TSH levels respectively in the adjusted model. Sex stratified analysis demonstrated that the decreased neonatal TSH levels were observed both in male infants and female infants, and the decrease was greater in male infants in urinary Ce. There were no significant interactions between maternal urinary Ce, Yb and infant sex (Ce: P for interaction = 0.173, Yb: P for interaction = 0.967).

CONCLUSIONS

Our findings demonstrated that increased maternal urinary Ce and Yb were associated with decreased neonatal TSH levels. Further researches from different populations are warranted to verify the association and to explore the mechanisms.

Effects of Maternal Supplementation with Rare Earth Elements during Late Gestation and Lactation on Performances, Health, and Fecal Microbiota of the Sows and Their Offspring

Simple Summary

The immunological and metabolic status of breeding sows directly affect the overall productivity of porcine operations. Especially, maternal health status during the transition from gestation to lactation are important in maintaining health and growth of the suckling piglets. Rare earth elements (REEs) have been considered as a promising natural feed additive and been reported to exert their activity locally within the gastrointestinal tract, including effects on the bacterial microflora and on nutrient utilization. The present study was conducted to explore the effects of dietary maternal REE supplementation during late gestation and lactation on sows and their offspring. After the experiment, we found that maternal REE addition enhanced antioxidant activity and immunity of sows and their suckling piglets. At the same time, REE supplementation during perinatal period improved the reproductivity of the sows as well as the growth of their offspring. Besides, maternal REEs supply altered the intestinal microbiota community and composition of sows as well as their offspring, and Spearman correlation analysis shows that fecal bacteria are associated with the antioxidase, inflammatory factors of the sows and offspring as well as average daily gain of the suckling piglets. In addition, our results suggested that REE supplementation during both gestation and lactation are more beneficial to sows and their offspring than supplementation during only late gestation. This paper holds promise in providing efficient feeding strategies in swine production.

Abstract

The study was conducted to investigate the effects of maternal supplementation with rare earth elements (REEs) on sows and their offspring. During late gestation, 120 multiparous sows were divided randomly into the control group (Basal diet) and REE-G group (Basal diet supplemented with 200 mg REE/kg). After delivery, REE-G group was further divided into two groups: REE-L- (Change to basal diet during lactation) and REE-L+ group (REE diet all the time). Our results showed that maternal REE supplementation improved the antioxidant and immunity of sows and piglets. Additionally, REE supply during late gestation significantly decreased the coefficient of within-litter variation (CV) in birth weight and increased the weaning weights and the average daily gain (ADG) of piglets. During lactation, the insulin-like growth factor-1 (IGF-1) levels in piglets of REE-L+ group were higher, while no difference between REE-L- and the control group. More beneficial bacteria (Christensenellaceae and Ruminococcaceae) were found in the REE-L+ group while some opportunistic pathogens (Proteobacteria and Campylobacter) were relatively suppressed. Fecal microbiota showed correlation with antioxidase, inflammatory factors, and average daily gain (ADG). Collectively, our findings indicated that REEs added in both gestation and lactation was more conducive to establish a healthier status for sows and their offspring.

Perspectives for rare earth elements as feed additive in livestock - A review

There is a need for newer feed additives due to legal prohibition on inclusion of growth promoting antibiotics in livestock diets in several countries due to antimicrobial resistance. In this context, rare earth elements (REE) have gained attention among animal nutritionists as potential growth promoters. Currently, several studies have reported better weight gain, milk production, egg laying capacity and feed conversion efficiency among different breeds of farm animals following supplementation with REE, with however largely inconsistent results. Furthermore, REE supplementation has also shown to improve ruminal fibrolytic and proteolytic activities as well as flavor of meat with negligible residues in edible tissue, however the mechanism behind this action is still unclear. According to existing research, due to their poor absorption and similarity with calcium REE might exert their action locally on gut microbial populations within the gastrointestinal tract (GIT). Moreover, REE have also shown anti-inflammatory, anti-oxidative as well as immune stimulating effects. The present review aims to broaden the knowledge about use of REE as feed additives for livestock and sum up efficacy of REE supplementation on performance and health of animals by comparing the findings. Till date, researches with REE have shown properties that make them a promising, new and safe alternative feed additive but further exploration is recommended to optimize effects and clarify discrepancy of various results before practical proposals can be drafted.

Impacts of rare earth elements on animal health and production: Highlights of cerium and lanthanum

Because the use of antibiotics as growth promoters was banned due to global health concerns, researchers are focusing on exploring alternative safe and effective feed additives. Rare earth elements (REEs) are located in group III of the periodic table, which includes cerium (Ce), lanthanum (La), and other elements. Recently, REEs have been involved in many medical, industrial, zootechnical, and agricultural applications. They play a pivotal role in functional and structural molecules in the biological system. Currently, in veterinary practice, REEs have been introduced as new feed additives to improve animal health and production. Based on the previous literature, REEs reportedly enhance milk, egg, and meat production. However, the controversy between adverse (e.g., toxicological and ecotoxicological) and favourable REE-associated effects has not been fully discussed. This review summarizes the relevant literature on the impacts of REEs on animal production and health; specifically, this review emphasizes the application of REEs as alternative safe feed additives used to promote animal growth and performance.

Human exposures to rare earth elements: Present knowledge and research prospects

The extensive use of rare earth elements (REEs) in a number of technologies is expected to impact on human health, including occupational and environmental REE exposures. A body of experimental evidence on REE-associated toxicity has been accumulated in recent decades, thus providing extensive background information on the adverse effects of REE exposures. Unlike experimental studies, the consequences of REE exposures to human health have been subjected to relatively fewer investigations. Geographical studies have been conducted on residents in REE mining districts, reporting on REE bioaccumulation, and associations between REE residential exposures and adverse health effects. A recent line of studies has associated tobacco smoking and indoor smoke with increased levels of some REEs in exposed residents. A body of literature has been focused on occupational REE exposures, with the observation of respiratory tract damage. The occupations related to REE mining and processing have shown REE bioaccumulation in scalp hair, excess REE urine levels, and defective gene expression. As for other REE occupational exposures, mention should be made of: a) jobs exposing to REE aerosol, such as movie operator; b) e-waste processing and, c) diesel engine repair and maintenance, with exposures to exhaust microparticulate (containing nanoCeO₂ as a catalytic additive). Diesel exhaust microparticulate has been studied in animal models, leading to evidence of several pathological effects in animals exposed by respiratory or systemic routes. A working hypothesis for REE occupational exposures is raised on REE-based supermagnet production and manufacture, by reviewing experimental studies that suggest several pathological effects of static magnetic fields, and warrant further investigations.

Sources, behaviour, and environmental and human health risks of high-technology rare earth elements as emerging contaminants

Recent studies show that high-technology rare earth elements (REEs) of anthropogenic origin occur in the environment including in aquatic systems, suggesting REEs are contaminants of emerging concern. However, compared to organic contaminants, there is a lack of comprehensive reviews on the anthropogenic sources, environmental behaviour, and public and ecological health risks of REEs. The current review aims to: (1) identify anthropogenic sources, transfer mechanisms, and environmental behaviour of REEs; (2) highlight the human and ecological health risks of REEs and propose mitigation measures; and (3) identify knowledge gaps and future research directions. Out of the 17 REEs, La, Gd, Ce and Eu are the most studied. The main sources of anthropogenic REE include; medical facilities, petroleum refining, mining and technology industries, fertilizers, livestock feeds, and electronic wastes and recycling plants. REEs are mobilized and transported in the environment by hydrological and wind-driven processes. Ecotoxicological effects include reduced plant growth, function and nutritional quality, genotoxicity and neurotoxicity in animals, trophic bioaccumulation, chronic and acute toxicities in soil organisms. Human exposure to REEs occurs via ingestion of contaminated water and food, inhalation, and direct intake during medical administration. REEs have been detected in human hair, nails, and biofluids. In humans, REEs cause nephrogenic systemic fibrosis and severe damage to nephrological systems associated with Gd-based contrast agents, dysfunctional neurological disorder, fibrotic tissue injury, oxidative stress, pneumoconiosis, cytotoxicity, anti-testicular effects, and male sterility. Barring REEs in medical devices, epidemiological evidence directly linking REEs in the environment to human health conditions remains weak. To minimize health risks, a conceptual framework and possible mitigation measures are highlighted. Future research is needed to better understand sources, environmental behaviour, ecotoxicology, and human epidemiology. Moreover, research on REEs in developing regions, including Africa, is needed given prevailing conditions predisposing humans to health risks (e.g., untreated drinking water).

Impact of rare earth element-enriched yeast on growth performance, nutrient digestibility, blood profile, and fecal microflora in finishing pigs

This study was conducted to evaluate effects of rare earth element-enriched yeast (RY) on growth performance, nutrient digestibility, blood profile, and fecal microbial flora in finishing pigs. A total of 100 finishing pigs [(Landrace × Yorkshire) × Duroc] were used in a two-phase feeding trial. Pigs were randomly assigned to five treatments according to their initial body weight (five pens per treatment, two gilts and two barrows per pen). Treatments were basal diets, free of antibiotics [negative control (NC)]; NC + 500, 1000, and 1500 mg kg−1, respectively, of RY; antibiotics diets, NC + 500 mg kg−1 of tiamulin [positive control (PC)]. Overall, average daily gain (ADG) and gain to feed ratio (G:F) increased linearly with increasing level of RY in diets. At the end of the experiment, blood lymphocyte concentration and apparent total tract digestibility of dry matter and gross energy increased linearly in pigs fed the increasing level of RY in diets. The better ADG, G:F, and fecal Lactobacillus counts were observed in both RY and PC groups compared with the NC group. In conclusion, diets with RY improved growth performance, digestibility, blood lymphocyte counts, and fecal Lactobacillus counts in finishing pigs, and RY may be considered as an alternative to antibiotics.

Behavioral deficits and neural damage of Caenorhabditis elegans induced by three rare earth elements

Rare earth elements (REEs) are widely used in industry, agriculture, medicine and daily life in recent years. However, environmental and health risks of REEs are still poorly understood. In this study, neurotoxicity of trichloride neodymium, praseodymium and scandium were evaluated using nematode Caenorhabditis elegans as the assay system. Median lethal concentrations (48 h) were 99.9, 157.2 and 106.4 mg/L for NdCl₃, PrCl₃ and ScCl₃, respectively. Sublethal dose (10-30 mg/L) of these trichloride salts significantly inhibited body length of nematodes. Three REEs resulted in significant declines in locomotor frequency of body bending, head thrashing and pharyngeal pumping. In addition, mean speed and wavelength of crawling movement were significantly reduced after chronic exposure. Using transgenic nematodes, we found NdCl₃, PrCl₃ and ScCl₃ resulted in loss of dendrite and soma of neurons, and induced down-expression of dat-1::GFP and unc-47::GFP. It indicates that REEs can lead to damage of dopaminergic and GABAergic neurons. Our data suggest that exposure to REEs may cause neurotoxicity of inducing behavioral deficits and neural damage. These findings provide useful information for understanding health risk of REE materials.

Nanoparticles and Cell Longevity

The field of engineering has made substantial strides in nanotechnology, in the realm of materials science and construction of nanoscale devices. Nanomedicine encompasses application of cutting edge engineered nanostructures to biological systems and development of novel strategies for disease intervention. In the current review, we discuss the pharmacological application of nanoparticles as free radical scavengers and the capacity of nanoparticles to promote cell and organismal longevity.

Rare earth elements in human and animal health: State of art and research priorities

BACKGROUND

A number of applications have been developed using rare earth elements (REE), implying several human exposures and raising unsolved questions as to REE-associated health effects.

METHODS

A MedLine survey was retrieved from early reports (1980s) up to June 2015, focused on human and animal exposures to REE. Literature from animal models was selected focusing on REE-associated health effects.

RESULTS

Some REE occupational exposures, in jobs such as glass polishers, photoengravers and movie projectionists showed a few case reports on health effects affecting the respiratory system. No case-control or cohort studies of occupational REE exposures were retrieved. Environmental exposures have been biomonitored in populations residing in REE mining areas, showing REE accumulation. The case for a iatrogenic REE exposure was raised by the use of gadolinium-based contrast agents for nuclear magnetic resonance. Animal toxicity studies have shown REE toxicity, affecting a number of endpoints in liver, lungs and blood. On the other hand, the use of REE as feed additives in livestock is referred as a safe and promising device in zootechnical activities, possibly suggesting a hormetic effect both known for REE and for other xenobiotics. Thus, investigations on long-term exposures and observations are warranted.

CONCLUSION

The state of art provides a limited definition of the health effects in occupationally or environmentally REE-exposed human populations. Research priorities should be addressed to case-control or cohort studies of REE-exposed humans and to life-long animal experiments.

Molecular mechanisms of silk gland damage caused by phoxim exposure and protection of phoxim-induced damage by cerium chloride in Bombyx mori

It is known that exposure to organophosphorus pesticides (OP) including phoxim can produce oxidative stress, neurotoxicity, and greatly attenuate cocooning rate in the silkworm, Bombyx mori. Cerium treatment has been demonstrated to relieve phoxim-induced toxicity in B. mori; however, very little is known about the molecular mechanisms of silk gland injury due to OP exposure and protection of gland damage due to cerium pretreatment. The aim of this study was to evaluate silk gland damage and its molecular mechanisms in phoxim-induced silkworm toxicity and the protective mechanisms of cerium following exposure to phoxim. The results showed that phoxim exposure resulted in severe gland damage, reductions in protein synthesis and the cocooning rate of silkworms. Cerium (Ce) attenuated gland damage caused by phoxim, promoted protein synthesis, increased the antioxidant capacity of the gland and increased the cocooning rate of B. mori. Furthermore, digital gene expression data suggested that phoxim exposure led to significant up-regulation of 714 genes and down-regulation of 120 genes. Of these genes, 122 were related to protein metabolism, specifically, the down-regulated Ser2, Ser3, Fib-L, P25, and CYP450. Ce pretreatment resulted in up-regulation of 162 genes, and down-regulation of 141 genes, importantly, Ser2, Ser3, Fib-L, P25, and CYP333B8 were up-regulated. Treatment with CeCl3 + phoxim resulted in higher levels of Fib-L, P25, Ser2, Ser3, CAT, TPx, and CYP333B8 expression in the silk gland of silkworms. These findings indicated that Ce increased cocooning rate via the promotion of silk protein synthesis-related gene expression in the gland under phoxim-induced toxicity. These findings may expand the application of rare earths in sericulture.

Mechanisms of larval midgut damage following exposure to phoxim and repair of phoxim-induced damage by cerium in Bombyx mori

Bombyx mori is an important economic animal for silk production. However, it is liable to be infected by organophosphorus pesticide that can contaminate its food and growing environment. It has been known that organophosphorus pesticide including phoxim exposure may damage the digestive systems, produce oxidative stress and neurotoxicity in silkworm B. mori, whereas cerium treatment has been demonstrated to relieve phoxim-induced toxicity in B. mori. However, very little is known about the molecular mechanisms of midgut injury due to phoxim exposure and B. mori protection after cerium pretreatment. The aim of this study was to evaluate the midgut damage and its molecular mechanisms, and the protective role of cerium in B. mori following exposure to phoxim. The results showed that phoxim exposure led to severe midgut damages and oxidative stress; whereas cerium relieved midgut damage and oxidative stress caused by phoxim in B. mori. Furthermore, digital gene expression suggested that phoxim exposure led to significant up-regulation of 94 genes and down-regulation of 52 genes. Of these genes, 52 genes were related with digestion and absorption, specifically, the significant alterations of esterase, lysozyme, amylase 48, and lipase expressions. Cerium pretreatment resulted in up-regulation of 116 genes, and down-regulation of 29 genes, importantly, esterase 48, lipase, lysozyme, and α-amylase were up-regulated. Treatment with Phoxim + CeCl3 resulted in 66 genes up-regulation and 39 genes down-regulation; specifically, levels of esterase 48, lipase, lysozyme, and α-amylase expression in the midgut of silkworms were significantly increased. Therefore, esterase 48, lipase, lysozyme, and α-amylase may be potential biomarkers of midgut toxicity caused by phoxim exposure. These findings may expand the application of rare earths in sericulture.

Effects of supplementing rare earth element cerium on rumen fermentation, nutrient digestibility, nitrogen balance and plasma biochemical parameters in beef cattle

The objectives of the trial were to investigate the effects of supplementing rare earth element (REE) cerium (Ce) on rumen fermentation, nutrient digestibility, methane (CH4 ) production, nitrogen (N) balance and plasma biochemical parameters in beef cattle. Four Simmental male cattle, aged at 14 months, with initial liveweight of 355 ± 8 kg and fitted with permanent rumen cannulas, were used as experimental animals. The cattle were fed with a total mixed ration (TMR) composed of concentrate mixture and corn silage. Four levels of cerium chloride (CeCl3 ·7H2 O, purity 99.9%), that is 0, 80, 160 and 240 mg CeCl3 /kg DM, were added to basal ration in a 4 × 4 Latin square design. Each experimental period lasted 15 days, of which the first 12 days were for pre-treatment and the last 3 days were for sampling. The results showed that supplementing CeCl3 at 160 or 240 mg/kg DM increased neutral detergent fibre (NDF) digestibility (p < 0.05) and tended to increased acid detergent fibre (ADF) digestibility (p = 0.083). Supplementing CeCl3 at 80, 160 or 240 mg/kg DM decreased the molar ratio of rumen acetate to propionate linearly (p < 0.05). Supplementing CeCl3 at 160 or 240 mg/kg DM decreased total N excretion, urinary N excretion and increased N retention (p < 0.05), increased excretion of total urinary purine derivatives (PD) (p < 0.05) and decreased CH4 /kg DMI (p < 0.05). In conclusion, supplementing CeCl3 at 160 or 240 mg/kg DM in the ration of beef cattle increased the digestibility of NDF, decreased the molar ratio of rumen acetate to propionate, increased N retention and microbial N flow and decreased CH4 /kg DMI.

Kidney injury and alterations of inflammatory cytokine expressions in mice following long-term exposure to cerium chloride

It has been demonstrated that the organic damages of animals can be caused by exposure to lanthanide oxides or compounds. However, the molecular mechanism of CeCl3 -induced kidney injury remains unclear. In this study, the mechanism of nephric damage in mice induced by an intragastric administration of CeCl3 was investigated. The results showed that Ce(3+) was accumulated in the kidney, which in turn led to oxidative stress, severe nephric inflammation, and dysfunction in mice. Furthermore, CeCl3 activated nucleic factor κB, which in turn increased the expression levels of tumor necrosis factor α, macrophage migration inhibitory factor, interleukin-2, interleukin-4, interleukin-6, interleukin-8, interleukin-10, interleukin-18, interleukin-1β, cross-reaction protein, transforming growth factor-β, interferon-γ, and CYP1A1, while suppressed heat shock protein 70 expression. These findings implied that Ce(3+) -induced kidney injury of mice might be associated with oxidative stress, alteration of inflammatory cytokine expression, and reduction of detoxification of CeCl3 .

Environmental fate and ecotoxicity of lanthanides: are they a uniform group beyond chemistry?

Lanthanides are a chemically uniform group of metals (La-Lu) that, together with yttrium (Y) and scandium (Sc), form the group of rare earth elements (REEs). Because of their many applications (e.g., agriculture, medicine, motor industry), their global production has increased exponentially in the last decades and their biogeochemical cycles are being disrupted by human uses (e.g., gadolinium anomalies in freshwater and tap water, REEs enrichment of soils as a consequence of agricultural practices). However, ecotoxicological effects and mechanism of action of these elements are still poorly understood. In particular, there is no consensus as to lanthanides showing a coherent and predictable pattern of (eco)toxicity in the same way as their atomic properties. For aquatic organisms, contradictory conclusions on this issue can be found in the bibliography. This review shows that the variable composition of culture media used in ecotoxicology, and the associated differences in lanthanide's speciation, are the most likely cause for such discrepancies. In particular, the formation of insoluble species in some highly complexing media likely leads to changes in the soluble concentration of lanthanide during some tests; with the potential for a generalized underestimation of their toxicity at the present state of knowledge. For terrestrial organisms, suitable studies to establish trends in lanthanides' toxicity are practically nonexistent; with most research focusing on the effects of REE mixtures. Molecular level studies to elucidate the mechanisms of action of lanthanides are essentially limited to La, pointing to the need for further research to identify common mechanisms of action or modes of action across lanthanides. Overall, agreement on the correct procedures to follow to obtain reliable and comparable data for individual lanthanide is the first action to take in order to arrive at a reliable risk assessment for this group of elements in both aquatic and terrestrial systems.

Gene expression profile in chronic mouse liver injury caused by long-term exposure to CeCl3

Numerous studies have demonstrated lanthanide (Ln) accumulation in the liver, and the corresponding damage; however, very little work has been done to evaluate the relationship between Ln-induced liver injury and its gene expression profile in mice. In this study, liver injury and gene-expressed profiles in male mice induced by oral administration of CeCl3 (2 mg/kg) via gavage for 90 consecutive days were investigated. The results showed that cerium accumulation, liver inflammation, and hepatocyte necrosis were observed. CeCl3 exposure significantly decreased the counts of white blood cells, lymphocyte, and platelet, the reticulocyte count (Ret) and neutrophilic granulocyte percentages as well as A/G ratio, whereas markedly increased the activities of alkaline phosphatase, lactate dehydrogenase, and cholinesterase, and the concentrations of triglycerides and total cholesterol. Furthermore, microarray results of liver showed that the differential expression of 675 known function genes involved in immune/inflammation response, apoptosis, metabolic process, cell cycle, cell proliferation, cytoskeleton, oxidative stress, signal transduction, transcription, translation, and transportation in CeCl3 exposed livers, respectively. Specifically, the significant downregulation of Nt5e led to inflammation, overexpressed Cyp4a12a and great suppression of Cdkn1a resulted in hepatocyte apoptosis, marked elevation of Cel, and Cyp7b1 expression caused the metabolic disorders in mouse liver after long-term CeCl3 exposure. Therefore, these genes may be in great relation to liver damages induced by exposure to CeCl3 .

Activating the expression of bacterial cryptic genes by rpoB mutations in RNA polymerase or by rare earth elements

Since bacteria were found to contain genes encoding enzymes that synthesize a plethora of potential secondary metabolites, interest has grown in the activation of these cryptic pathways. Homologous and heterologous expression of these cryptic secondary metabolite-biosynthetic genes, often “silent” under ordinary laboratory fermentation conditions, may lead to the discovery of novel secondary metabolites. We review current progress on this topic, describing concepts for activating silent genes. We especially focus on genetic manipulation of transcription and translation, as well as the utilization of rare earth elements as a novel method to activate the silent genes. The possible roles of silent genes in bacterial physiology are also discussed.

Rare-earth-incorporated polymeric vector for enhanced gene delivery

Cationic polymer PEI-CyD is doped with Nd by plasma technology to produce the gene vector: Nd@PEI-CyD. Luciferase expression and EGFP transfection experiments performed in vitro reveal that Nd@PEI-CyD has significantly higher transfection efficiency than lipofectamine 2000 and PEI-CyD and the mechanism is studied and proposed. The rare-earth element, Nd, stimulates the energy metabolism of cells, enhances cell uptake of complexes/pDNA, and regulates the cellular pathways. These special features suggest a new strategy involving metal-incorporated non-viral gene vectors.

Alternatives to antibiotics as growth promoters for use in swine production: a review

In the past two decades, an intensive amount of research has been focused on the development of alternatives to antibiotics to maintain swine health and performance. The most widely researched alternatives include probiotics, prebiotics, acidifiers, plant extracts and neutraceuticals such as copper and zinc. Since these additives have been more than adequately covered in previous reviews, the focus of this review will be on less traditional alternatives. The potential of antimicrobial peptides, clay minerals, egg yolk antibodies, essential oils, eucalyptus oil-medium chain fatty acids, rare earth elements and recombinant enzymes are discussed. Based on a thorough review of the literature, it is evident that a long and growing list of compounds exist which have been tested for their ability to replace antibiotics as feed additives in diets fed to swine. Unfortunately, the vast majority of these compounds produce inconsistent results and rarely equal antibiotics in their effectiveness. Therefore, it would appear that research is still needed in this area and that the perfect alternative to antibiotics does not yet exist.

Integrin-mediated signaling contributes to gadolinium-containing-particle-promoted cell survival and G₁ to S phase cell cycle transition by enhancing focal adhesion formation

We previously reported that Gd-containing particles formed under physiological conditions act as active entities to enhance cell survival and promote S phase entry via activation of both mitogen-activated protein kinase/extracellular-signal-regulated protein kinase (ERK) and phosphatidylinositol 3-kinase/Akt signaling pathways. However, how they transduce the extracellular signal inside the cell remains unclear. The present study demonstrates that Gd-containing particles can alleviate serum-deprivation-induced cell death and promote G₁ to S phase cell cycle progression by enhancing cell adhesion to the extracellular matrix. As an indicator of adhesion, the vinculin distribution was detected by confocal laser scanning microscopy. The control cells exhibited fewer and less typical focal adhesions. After treatment with Gd-containing particles, a large number of vinculin-containing focal adhesions were maintained. In the presence of integrin antagonists, the percentage of S phase entry induced by Gd-containing particles was decreased and the enhancement of cell viability was also attenuated, along with a decrease in both cyclin D expression and ERK phosphorylation. In summary, the present results suggest that the integrin-mediated signaling pathway plays an important role in cell survival and G₁ to S phase transition promoted by Gd-containing particles by enhancing focal adhesion formation. The results presented here provide novel evidence to advance knowledge leading to further understanding of the mechanisms of both cell proliferation and cell survival promoted by Gd and may be helpful for developing effective measures to prevent or treat nephrogenic systemic fibrosis.

Effect of rare earth elements on beef cattle growth performance, blood clinical chemical parameters and mitogen stimulated proliferation of bovine peripheral blood mononuclear cells in vitro and ex vivo

Rare earth elements (REE) are possible performance enhancers in animal production, but little is known about their effects on ruminants. Therefore a feeding trial was conducted with 40 fattening bulls who received 0, 100, 200 or 300mg REE-citrate/kg dry matter (DM), containing 34.30% La, 58.09% Ce and 7.61% other REE. DM intake was measured daily and live weight weekly. Ex vivo ConcanavalinA (ConA)-stimulated cell proliferation of peripheral blood mononuclear cells (PBMC) was tested by MTT and alamar blue (AB) assay. Serum was analysed for clinical chemical parameters, ion (Mg, Ca and P) and REE concentrations. The effects of LaCl(3), CeCl(3), NdCl(3) and YCl(3) on ConA-stimulated proliferation of PBMC were tested in vitro, using MTT and AB assay. REE-citrate supplementation did affect DM intake, but not live weight gain, clinical chemical parameters, and ion concentrations significantly. In REE-300 group ex vivo proliferation of PBMC was significantly increased. In vitro ConA-stimulated proliferation decreased with rising REE-chloride concentrations. At least at the highest tested concentration (approximately 290μM) the inhibition reached significance. Proliferation of non-stimulated PBMC was not affected dose-dependently. REE affect the proliferation of PBMC, thus an effect on the bovine immune system is possible. However, the great differences in effective doses in vitro and ex vivo (serum REE concentrations) might explain the different results from the experiments.

Effects of lanthanum, cerium, and neodymium on the nuclei and mitochondria of hepatocytes: accumulation and oxidative damage

The aim of this study was to investigate the contents of lanthanum (La), cerium (Ce), and neodymium (Nd) that accumulate in nuclei and mitochondria isolated from the liver and their corresponding potential oxidative damage effects on nuclei and mitochondria. Five-week-old male imprinting control region (ICR) mice were exposed to chlorides of La, Ce, or Nd by oral gavage with one of three doses: 10, 20, or 40 mg/kgBW/day for 6 weeks. The concentrations of administered elements in hepatocyte nuclei and mitochondria were determined with inductively coupled plasma-mass (ICP-MS) spectrometry. The accumulation of La, Ce, and Nd in hepatocyte nuclei and mitochondria gradually increased in a dose-dependent manner with exposure to the elements, although the concentrations of La, Ce, and Nd in hepatocyte mitochondria were lower than those in their counterpart nuclei. In hepatocyte nuclei, superoxide dismutase (SOD) and catalase (CAT) activities decreased, whereas glutathione peroxidase (GPx) activity, glutathione (GSH) and malondialdehyde (MDA) levels increased. In hepatocyte mitochondria, SOD, CAT, and GPx activities and GSH levels were significantly decreased, and MDA levels were significantly increased. These results suggest that La, Ce, and Nd presumably enter hepatocytes and mainly accumulate in the nuclei and induce oxidative damage in hepatic nuclei and mitochondria.

Responses of antioxidant systems after exposition to rare earths and their role in chilling stress in common duckweed (Lemna minor L.): a defensive weapon or a boomerang?

Extensive agriculture application of rare earth elements (REEs) in Far East countries might cause spreading of these metals in aquatic and terrestrial ecosystems, thus inducing a growing concern about their environmental impact. In this work the effects of a mix of different REE nitrate (RE) and of lanthanum nitrate (LA) on catalase and antioxidant systems involved in the ascorbate-glutathione cycle were investigated in common duckweed Lemna minor L. The results indicated that L. minor shows an overall good tolerance to the presence of REEs in the media. Treatments at concentrations up to 5 mM RE and 5 mM LA did not cause either visible symptoms on plants or significant effects on reactive oxygen species (ROS) production, chlorophyll content, and lipid peroxidation. Toxic effects were observed after 5 days of exposition to 10 mM RE and 10 mM LA. A remarkable increase in glutathione content as well as in enzymatic antioxidants was observed before the appearance of the stress symptoms in treated plants. Duckweed plants pretreated with RE and LA were also exposed to chilling stress to verify whether antioxidants variations induced by RE and LA improve plant resistance to the chilling stress. In pretreated plants, a decrease in ascorbate and glutathione redox state and in chlorophyll content and an increase in lipid peroxidation and ROS production levels were observed. The use of antioxidant levels as a stress marker for monitoring REE toxicity in aquatic ecosystems by means of common duckweed is discussed.

Isotopic tracer studies of chemical behavior of rare earth elements in environmental and biological sciences

Rare earth elements (REE), a group of elements with atomic numbers from 57 to 71, have been widely applied in recent years not only in industry but also in agriculture, forestry, animal husbandry and medicine. Numerous anthropogenic activities make REE to easily enter the environment and finally the human body via the food chain. Therefore, detailed studies on chemical behavior of these metals in environmental and biological systems are imperative. Isotopic tracer method is especially suited to such studies and has played an important role in assessing the environmental effects of REE. In this paper, some recent progress in the study of chemical behavior of REE in environmental and biological sciences made by the isotopic tracer method is outlined.

Effect of some light rare earth elements on seed germination, seedling growth and antioxidant metabolism in Triticum durum

Rare earth elements (REEs) enriched fertilizers have been commonly used in China since the 1980s, thus inducing a growing concern about their environmental impact in agriculture. In this work, the effect of some light REEs nitrate mixture and La(3+) nitrate on seed germination, seedling growth and antioxidant metabolism in Triticum durum was investigated with the aim of clarifying the potential benefits or damages of REEs on plants. Seed pre-soaking for 8 h with La(3+) and REEs nitrate inhibited seed germination at low concentrations (0.01 mM and 0.1 mM), while pre-soaking for 2 and 4 h already inhibited seed germination when higher concentrations (1 mM and 10 mM) of La(3+) and REEs nitrate were used. La(3+) and REEs nitrate treatment also affected seedling growth. Root growth was enhanced and inhibited at low and high concentrations, respectively. Shoot growth was inhibited by La(3+) and REEs nitrate at all tested concentrations after 12 d of treatments. Enzymatic and non enzymatic antioxidants were differently affected by La(3+) and REEs nitrate and their behaviour changed also depending on the plant organ. In roots La(3+) and REEs nitrate treatments induced an increase in ascorbate (ASC) and glutathione (GSH) contents. In shoots only La(3+) nitrate induced an increase in the ASC content whereas GSH decreased following both La(3+) and REEs nitrate treatments. An increase in ASC peroxidase activity was observed in shoots and roots, while catalase did not change in roots and slightly decreased in shoots. The possible role of the increase in some antioxidants as indicators of stress caused by lanthanide treatments is discussed.