Antioxidant and antigenotoxic potential of Morinda tinctoria Roxb. leaf extract succeeding cadmium exposure in Asian catfish, Pangasius sutchi

The present study investigated the protective effect of methanolic leaf extract of Morinda tinctoria. Roxb (MEMT) (200 mg/kg) via feed in supplementation with standard compound silymarin (400 mg/kg). M. tinctoria (Roxb.) belonging to Rubiaceae, is an evergreen shrub indigenous to unfarmed lands of tropical countries. It is considered as an essential traditional medicine attributing for the potential antioxidant and anti-inflammatory properties. The enhancements of antioxidant and antigenotoxic status in different tissues of cadmium (Cd) intoxicated Pangasius sutchi were evaluated by using various antioxidant assays (superoxide dismutase (SOD) and catalase (CAT) and lipid peroxidation) in addition to micronuclei (MN), binuclei (BN) and comet assay. The cadmium toxicated fish showed a significant (p < 0.001) increase in lipid peroxidation (LPO) activities in liver, gills, muscle and kidney whereas significant (p < 0.001) decline were observed in superoxide dismutase (SOD) and catalase (CAT) contents in all fish tissues. The results also revealed that, Cd exposure induced the formation of genotoxic endpoints like MN, BN, notched nuclei, kidney shaped nuclei and DNA damage in the fish erythrocytes. Maximum of 26.8% MN frequencies and maximum of 66.74% tail DNA damage were observed on the 7th day of Cd exposure. A time-dependent significant increase (p < 0.001) in the frequencies of MN, BN and tail DNA damage were observed in all treated groups against the control which started to decline from 14th day onwards. There was a decline in the LPO content, frequencies of MN, BN and percentage of tail DNA in contrast to significant elevation in SOD and CAT content in all tissues due to the combined treatment of M. tinctoria feed and water borne Cd exposure. It can be concluded from our observations that, supplementation of M. tinctoria leaf extract through feed alone produced enhanced antioxidant and antigenotoxic status in cadmium treated fish by diminishing oxidative stress and genotoxicity effects in a time dependent manner.

Evaluation of the hair cell regeneration and claudin b and phoenix gene expression during exposure to low concentrations of cadmium and zinc in early developing zebrafish larvae

Zebrafish possess hair cells on the body surface similar to that of mammals inner hear, in particular in the neuromasts, and due to its ability in regenerating damaged hair cells, is regularly used as a powerful animal model to study in vivo cytotoxicity. Among the factors leading to hair cell disruption, metal ions are of particular concern since they are important environmental pollutants. To date, several studies on zebrafish hair cell regeneration after metal exposure exist, while no data on regeneration during continuous metal exposure are available. In the present study, neuromast hair cell disruption and regeneration were assessed in zebrafish larvae for the first time during zinc (Zn) and cadmium (Cd) continuous exposure and a visual and molecular approach was adopted. Fluorescent vital dye DASPEI was used to assess hair cell regeneration and the gene expression of claudin b (cldnb) and phoenix (pho), was analyzed. Metallotionein-2 (mt2) gene expression was used as standard molecular marker of metal toxicity and confirmed the higher toxicity of Cd compared to Zn. In addition, Cd caused a delay in hair cell regeneration compared to Zn. Molecular analysis showed cldnb gene expression increased in relation to the metal concentrations used, confirming the involvement of this gene in hair cell regeneration. On the contrary, a dramatic decrease of pho gene expression was observed in Cd exposed groups, suggesting a negative impact of Cd on pho expression, thus negatively interfering with hair cell regeneration in zebrafish larvae exposed to this metal.

A requirement for autophagy in HMGA2-induced metabolic reprogramming to support Cd-induced migration

High mobility group A2 (HMGA2) is closely related to the occurrence, development and prognosis of tumors. But the mechanism is unclear. Metabolic reprogramming is a dominant way to meet anabolic and energy requirements of tumor cells for their survival, growth and proliferation. Here, we investigated the role of metabolic reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis mediated by HMGA2/autophagy axis in cadmium (Cd, CdCl₂)-induced migration. First, we found that Cd induced glycolysis and reduced OXPHOS in vivo (0.5 and 1 mg/kg, i.p. or 0.8 and 1.6 μM, i.t.) and in vitro (2 μM in A549 cells and 0.05 μM in HELF cells). Then, genetic knockdown of HMGA2 restored Cd-reduced mitochondrial mass and OXPHOS and inhibited Cd-increased glycolysis, indicating that HMGA2 was involved in Cd-induced metabolic reprogramming. 2-Deoxy-d-glucose (2DG, 5 mM), the inhibitor of glycolysis decreased Cd/HMGA2-induced cell migration and restored Cd/HMGA2-decreased OXPHOS and mitochondrial mass. Inhibition of autophagy by 3-Methyladenine (3MA, 3 mM) elucidated an essential role of autophagy in HMGA2-induced glycolysis, migration, and HMGA2-reduced OXPHOS. Overall, our study demonstrated that autophagy was required for HMGA2-mediated metabolic reprogramming, which was critical for Cd-induced migration. Targeting HMGA2 and autophagy-dependent reprogrammed metabolism may be an effective way to inhibit Cd-induced cell migration.

Role of hepcidin in oxidative stress and cell death of cultured mouse renal collecting duct cells: protection against iron and sensitization to cadmium

The liver hormone hepcidin regulates systemic iron homeostasis. Hepcidin is also expressed by the kidney, but exclusively in distal nephron segments. Several studies suggest hepcidin protects against kidney damage involving Fe2+ overload. The nephrotoxic non-essential metal ion Cd2+ can displace Fe2+ from cellular biomolecules, causing oxidative stress and cell death. The role of hepcidin in Fe2+ and Cd2+ toxicity was assessed in mouse renal cortical [mCCD(cl.1)] and inner medullary [mIMCD3] collecting duct cell lines. Cells were exposed to equipotent Cd2+ (0.5-5 μmol/l) and/or Fe2+ (50-100 μmol/l) for 4-24 h. Hepcidin (Hamp1) was transiently silenced by RNAi or overexpressed by plasmid transfection. Hepcidin or catalase expression were evaluated by RT-PCR, qPCR, immunoblotting or immunofluorescence microscopy, and cell fate by MTT, apoptosis and necrosis assays. Reactive oxygen species (ROS) were detected using CellROX™ Green and catalase activity by fluorometry. Hepcidin upregulation protected against Fe2+-induced mIMCD3 cell death by increasing catalase activity and reducing ROS, but exacerbated Cd2+-induced catalase dysfunction, increasing ROS and cell death. Opposite effects were observed with Hamp1 siRNA. Similar to Hamp1 silencing, increased intracellular Fe2+ prevented Cd2+ damage, ROS formation and catalase disruption whereas chelation of intracellular Fe2+ with desferrioxamine augmented Cd2+ damage, corresponding to hepcidin upregulation. Comparable effects were observed in mCCD(cl.1) cells, indicating equivalent functions of renal hepcidin in different collecting duct segments. In conclusion, hepcidin likely binds Fe2+, but not Cd2+. Because Fe2+ and Cd2+ compete for functional binding sites in proteins, hepcidin affects their free metal ion pools and differentially impacts downstream processes and cell fate.

Analyzing dose dependency of antioxidant defense system in the cyanobacterium Nostoc muscorum Meg 1 chronically exposed to Cd2

The aim of the present study was to analyze the dose dependency of oxidant-antioxidant homeostasis in Cd²⁺ exposed Nostoc muscorum Meg 1 cells. Quantification of percent DNA loss, protein oxidation and lipid peroxidation was carried out to assess Cd²⁺ induced ROS mediated damages to the organism. The countermeasures adopted by the cyanobacterium were also evaluated by computing various components of both enzymatic and non-enzymatic antioxidants. Exposure to different Cd²⁺ (0.1, 0.2, 0.3, 0.5, 1, 1.5, 2, 2.5, 3 ppm) doses showed substantial increase in ROS content in the ranges of 20-181% and 116-323% at the end of first and seventh day. The DNA damage, protein oxidation and lipid peroxidation were increased by 11-62%, 7-143% and 13-183% with increasing Cd²⁺ concentrations at the end of seven days. TEM images clearly showed damages to the cell wall, cell membrane and thylakoid organization at higher Cd²⁺ (0.5-3 ppm) concentrations. Cd²⁺ exposure up to 0.5 ppm registered increase in contents of antioxidative enzymes (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR)) and in non-enzymatic antioxidants (glutathione, total thiol, phytochelatin and proline) indicating stimulation of ROS mitigating machinery. However, toxicity of Cd²⁺ was evident as at higher concentrations the cellular morphology and ultra-structures were negatively affected and the capacities of the cells to generate various antioxidant measures were highly compromised. The organism registered 96-98% sorption ability from a solution supplemented with 0.3 ppm Cd²⁺ and thus show realistic potential as Cd²⁺ bioremediator in wastewater treatment.

Adverse cardiovascular effects of exposure to cadmium and mercury alone and in combination on the cardiac tissue and aorta of Sprague-Dawley rats

The aim of this study was to identify cardiovascular effects of relevant concentrations of Cd and Hg alone and in combination as a mixture in water. This was achieved by administering to male Sprague-Dawley rats via gavage 0.62 mg/kg Cd or 1.23 mg/kg Hg, or a combination of 0.62 mg/kg Cd and 1.23 mg/kg Hg in the co-exposure group for 28 days. Concentrations were the rat equivalence dosages of 1,000 times the World Health Organization's limits of 0.003 mg/L and 0.006 mg/L for Cd and Hg, respectively, for water. With termination, blood levels of the metals were increased. For all metal exposed groups, histological evaluation and transmission electron microscopy of the myocardium revealed myofibrillar necrosis, increased fibrosis, vacuole formation and mitochondrial damage. Cd caused the most mitochondrial damage while Hg to a greater degree induced fibrosis. In the aorta, both Cd and Hg also increased collagen deposition adversely altering the morphology of the fenestrated elastic fibers in the tunica media. Co-exposure resulted in increased cardiotoxicity with increased mitochondrial damage, fibrosis and distortion of the aortic wall as a result of increased collagen deposition, as well as altered elastin deposition, fragmentation and interlink formation. These are typical features of oxidative damage that correlates with a phenotype of premature ageing of the CVS that potentially can lead to hypertension and premature cardiac failure.

Do Only Calcium and Vitamin D Matter? Micronutrients in the Diet of Inflammatory Bowel Diseases Patients and the Risk of Osteoporosis

Osteoporosis is one of the most common extraintestinal complications among patients suffering from inflammatory bowel diseases. The role of vitamin D and calcium in the prevention of a decreased bone mineral density is well known, although other nutrients, including micronutrients, are also of extreme importance. Despite the fact that zinc, copper, selenium, iron, cadmium, silicon and fluorine have not been frequently discussed with regard to the prevention of osteoporosis, it is possible that a deficiency or excess of the abovementioned elements may affect bone mineralization. Additionally, the risk of malnutrition, which is common in patients with ulcerative colitis or Crohn's disease, as well as the composition of gut microbiota, may be associated with micronutrients status.

Enhanced Zinc Intake Protects against Oxidative Stress and Its Consequences in the Brain: A Study in an In Vivo Rat Model of Cadmium Exposure

We examined, in a rat model of moderate environmental human exposure to cadmium (Cd), whether the enhanced intake of zinc (Zn) may protect against Cd-caused destroying the oxidative/antioxidative balance and its consequences in the brain. The intoxication with Cd (5 mg/L, 6 months) weakened the enzymatic (superoxide dismutase, glutathione peroxidase, catalase) and non-enzymatic (total thiol groups, reduced glutathione) antioxidative barrier decreasing the total antioxidative status and increased the concentrations of pro-oxidants (hydrogen peroxide, myeloperoxidase) in this organ and its total oxidative status. These resulted in the development of oxidative stress and oxidative modifications of lipids and proteins. The co-administration of Zn (30 and 60 mg/L enhancing this element intake by 79% and 151%, respectively) importantly protected against Cd accumulation in the brain tissue and this xenobiotic-induced development of oxidative stress and oxidative damage to lipids and proteins. Moreover, this bioelement also prevented Cd-mediated oxidative stress evaluated in the serum. The favorable effect of Zn was caused by its independent action and interaction with Cd. Concluding, the enhancement of Zn intake under oral exposure to Cd may prevent the oxidative/antioxidative imbalance and oxidative stress in the brain and thus protect against injury of cellular macromolecules in the nervous system.

Sodium metavanadate treatment improves glycogen levels in multiple tissues in a model of metabolic syndrome caused by chronic cadmium exposure in Wistar rats

Cadmium, one of the more hazardous environmental contaminants, has been proposed as a metabolic disruptor. Vanadium has emerged as a possible treatment for metabolic diseases. Both metals are important in public health. We aimed to investigate whether vanadium treatment is effective against metabolic disturbances caused by chronic exposure to the lowest-observable adverse effect level of cadmium. Male Wistar rats were exposed to cadmium (32.5 ppm) in drinking water for 3 months. Metabolic complications such as overweight, visceral adipose gain, hyperglycemia, impaired glucose tolerance, and dyslipidemia were detected, and low glycogen levels and steatosis were observed in the tissues. Then, the control and treated animals were subdivided and treated with a solution of 5 μM NaVO₃/kg/twice a week for 2 months. The control-NaVO₃ group did not show zoometric or metabolic changes. A strong interaction of NaVO₃ treatment over cadmium metabolic disruption was observed. The vanadium accumulation diminished cadmium concentration in tissues. Also, vanadium interaction improved glucose homeostasis. The major effect was observed on glycogen synthesis, which was fully recovered in all tissues analyzed. Additionally, vanadium treatment prevented overweight and visceral fat accumulation, improving BMI and the percentage of fat. However, NaVO₃ treatment did not have an effect on dyslipidemia or steatosis. In conclusion, this work shows that vanadium administration has a strong effect against metabolic disturbances caused by chronic cadmium exposure, observing powerful interaction on glucose homeostasis.

Fluorescence determination of trace level of cadmium with pyrene modified nanocrystalline cellulose in food and soil samples

Cadmium is one of the most toxic metal that accumulates in the human body via food chain, industrial/agricultural activites. It also has negative effects in organs such as the brain, liver and central nervous system. Therefore, International Agency for Research on Cancer is classified cadmium as "carcinogenic to humans" (group 1). In this work, novel pyrene modified nanocrystalline cellulose (NP-1) was designed as a fluorescence sensor for selective determination of Cd²⁺ in food and soil samples. FTIR, UV-Vis, SEM, TEM and TGA were used for structural, morphological characterizations and thermal properties of NP-1. The experimental conditions such as selectivity, pH, sensor concentration, photostability, time and interaction mechanism were examined and optimized. The LOD was determined as 0.09 μM (10.70 μg/L) which was lower than WHO's permissible limit of cadmium in plant with 0.10-60.00 μM linear working range. Validation of the present method was performed by spike/recovery test and ICP-MS, then fluorescence determination of Cd²⁺ in food and soil samples was succesfully applied. The results indicated that the proposed method based on "turn-on" fluorescence of NP-1 was a simple, sensitive and reliable for rapid determination of Cd²⁺ in real samples with high applicability and stability.

Cadmium-Induced Cell Homeostasis Impairment is Suppressed by the Tor1 Deficiency in Fission Yeast

Cadmium has no known physiological function in the body; however, its adverse effects are associated with cancer and many types of organ system damage. Although much has been shown about Cd toxicity, the underlying mechanisms of its responses to the organism remain unclear. In this study, the role of Tor1, a catalytic subunit of the target of rapamycin complex 2 (TORC2), in Cd-mediated effects on cell proliferation, the antioxidant system, morphology, and ionome balance was investigated in the eukaryotic model organism Schizosaccharomyces pombe. Surprisingly, spectrophotometric and biochemical analyses revealed that the growth rate conditions and antioxidant defense mechanisms are considerably better in cells lacking the Tor1 signaling. The malondialdehyde (MDA) content of Tor1-deficient cells upon Cd treatment represents approximately half of the wild-type content. The microscopic determination of the cell morphological parameters indicates the role for Tor1 in cell shape maintenance. The ion content, determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), showed that the Cd uptake potency was markedly lower in Tor1-depleted compared to wild-type cells. Conclusively, we show that the cadmium-mediated cell impairments in the fission yeast significantly depend on the Tor1 signaling. Additionally, the data presented here suggest the yet-undefined role of Tor1 in the transport of ions.

Micro-RNAs: Crossroads between the Exposure to Environmental Particulate Pollution and the Obstructive Pulmonary Disease

Environmental pollution has reached a global echo and represents a serious problem for human health. Air pollution encompasses a set of hazardous substances, such as particulate matter and heavy metals (e.g., cadmium, lead, and arsenic), and has a strong impact on the environment by affecting groundwater, soil, and air. An adaptive response to environmental cues is essential for human survival, which is associated with the induction of adaptive phenotypes. The epigenetic mechanisms regulating the expression patterns of several genes are promising candidates to provide mechanistic and prognostic insights into this. Micro-RNAs (miRNAs) fulfil these features given their ability to respond to environmental factors and their critical role in determining phenotypes. These molecules are present in extracellular fluids, and their expression patterns are organ-, tissue-, or cell-specific. Moreover, the experimental settings for their quantitative and qualitative analysis are robust, standardized, and inexpensive. In this review, we provide an update on the role of miRNAs as suitable tools for understanding the mechanisms behind the physiopathological response to toxicants and the prognostic value of their expression pattern associable with specific exposures. We look at the mechanistic evidence associable to the role of miRNAs in the processes leading to environmental-induced pulmonary disease (i.e., chronic obstructive pulmonary disease).

The Impact of a Polyphenol-Rich Extract from the Berries of Aronia melanocarpa L. on Collagen Metabolism in the Liver: A Study in an In Vivo Model of Human Environmental Exposure to Cadmium

This study examined whether a polyphenol-rich extract from the berries of Aronia melanocarpa L. (AE; chokeberries) may protect from the impact of cadmium (Cd) on the metabolism of collagen in the liver. The study was conducted in an experimental model (rats that were fed a diet containing 1 or 5 mg Cd/kg for 3-24 months) of human exposure to this xenobiotic during a lifetime. The concentration of total collagen and the expression of collagen types I and III at the mRNA and protein levels, as well as the concentrations of matrix metalloproteinases (MMP-1 and MMP-2) and their tissue inhibitors (TIMP-1 and TIMP-2), were assayed. The administration of Cd and/or AE had only a slight and temporary impact on the concentration of total collagen in the liver. The supplementation with AE significantly prevented Cd-mediated changes in the expression of collagen types I and III at the mRNA and protein levels and their ratio (collagen III/collagen I), as well as a rise in the concentrations of MMPs and TIMPs in this organ. The results allow the conclusion that the intake of chokeberry products in the case of Cd intoxication may be effective in prevention from this xenobiotic-induced disturbance in collagen homeostasis in the liver.

Effect of the Interaction Between Cadmium Exposure and CLOCK Gene Polymorphisms on Thyroid Cancer: a Case-Control Study in China

The exposure to endocrine disruptors and the disruption of the circadian rhythms can both affect thyroid hormones, with results that are most likely carcinogenic in humans. The effects of cadmium (Cd) level and circadian-related single-nucleotide polymorphisms (SNPs) on thyroid cancer (TC) risk have rarely been reported. In this study, the associations of urine Cd, CLOCK gene polymorphisms, and TC risk were evaluated, in addition to the effect of the gene-environment interaction on TC risk. In this case-control study, 218 TC cases and 218 controls were enrolled. Cd in urinary samples was determined by atomic absorption spectrometry. Three SNPs (rs3805151, rs3805154, and rs78929565) were genotyped with an improved multiplex ligation detection reaction technique. The individuals with a high Cd level were 1.72-fold more likely to have TC (OR = 1.72, 95%CI 1.04-2.85), and a high Cd level was associated with higher tumor T stage and N stage (OR = 2.42, 95%CI 1.28-4.58; OR = 3.26, 95%CI 1.67-6.33, respectively). Individuals with TT genotype of rs78929565 had a 107 % increase in TC risk (OR = 2.07, 95%CI 1.00-4.29). Cases with CT genotype tended to have a higher AJCC stage (OR = 2.79, 95% CI 1.01-7.78). A significant interaction was detected between the rs78929565 variant and Cd exposure (p interaction = 0.04). The TT genotype carriers of rs78929565 with a high Cd level were more susceptible to thyroid cancer than the major homozygotes carriers who were exposed to a low cadmium level (OR = 2.66, 95%CI 1.07-6.59). These findings suggested that Cd exposure and the CLOCK variant genotypes were associated with TC risk and tumor severity. Individuals with minor allele of rs78929565 and higher Cd exposure had increased susceptibility to TC. Further studies are required to confirm these findings.

Maternal Exposure to Cadmium and Fetal Growth: a Systematic Review and Meta-Analysis

This study aims to review the epidemiological studies on the association between cadmium (Cd) exposure during pregnancy and neonatal anthropometric measures. Electronic search of PubMed, Scopus, Web of Science, and Cochrane Collaboration was conducted till end of 2018. Pooled estimates were performed using a fixed-effects model or random-effects model. A total of 22 studies included in the meta-analyses. Subgroup analyses on sample type (maternal urine, maternal blood, cord blood, and placenta), meta-regression, and sensitivity analysis were performed to seek the sources of heterogeneity. In the random-effects meta-analysis of included studies, the pooled correlation coefficient between maternal exposure to Cd with birth weight was - 0.04 [95% CI (- 0.07, - 0.01), with birth length and head circumference as - 0.01 [95% CI (- 0.04, 0.02)] and - 0.02 [95% CI (- 0.06, 0.02)]. Our findings showed significant relationship between Cd exposure of pregnant women with low birth weight, but not with birth length and head circumference.

Zinc protects against cadmium-induced toxicity in neonatal murine engineered cardiac tissues via metallothionein-dependent and independent mechanisms

Cadmium (Cd) is a nonessential heavy metal and a prevalent environmental toxin that has been shown to induce significant cardiomyocyte apoptosis in neonatal murine engineered cardiac tissues (ECTs). In contrast, zinc (Zn) is a potent metallothionein (MT) inducer, which plays an important role in protection against Cd toxicity. In this study, we investigated the protective effects of Zn against Cd toxicity in ECTs and explore the underlying mechanisms. ECTs were constructed from neonatal ventricular cells of wild-type (WT) mice and mice with global MT gene deletion (MT-KO). In WT-ECTs, Cd (5-20 μM) caused a dose-dependent toxicity that was detected within 8 h evidenced by suppressed beating, apoptosis, and LDH release; Zn (50-200 μM) dose-dependently induced MT expression in ECTs without causing ECT toxicity; co-treatment of ECT with Zn (50 µM) prevented Cd-induced toxicity. In MT-KO ECTs, Cd toxicity was enhanced; but unexpectedly, cotreatment with Zn provided partial protection against Cd toxicity. Furthermore, Cd, but not Zn, significantly activated Nrf2 and its downstream targets, including HO-1; inhibition of HO-1 by a specific HO-1 inhibitor, ZnPP (10 µM), significantly increased Cd-induced toxicity, but did not inhibit Zn protection against Cd injury, suggesting that Nrf2-mediated HO-1 activation was not required for Zn protective effect. Finally, the ability of Zn to reduce Cd uptake provided an additional MT-independent mechanism for reducing Cd toxicity. Thus, Zn exerts protective effects against Cd toxicity for murine ECTs that are partially MT-mediated. Further studies are required to translate these findings towards clinical trials.

Morpho-functional alterations in lymphocytes and erythrocytes of Japanese quail due to prolonged in vivo exposure to heavy metal complexes

BACKGROUND

Lead and cadmium are significant environmental pollutants that cause pathophysiological responses in many organs. Heavy metal absorption into many tissues is very fast due to a pronounced affinity for metallothioneins.

METHOD

Japanese quail were exposed to different concentrations of metals (cadmium 0.20 mg/L and lead 0.25 and 0.50 mg/L) for 20 days. Erythrocytes (normal and hemolyzed) and lymphocytes (normal and altered) were monitored in this study. The analysis observed the percentage of normal and altered cells, as well as erythrocyte surface area. Cell counts were analyzed using light microscopy, while surface area and cytological changes in cells and nuclei were analyzed using licensed software.

RESULTS

Different concentrations of metals have caused erythrocyte hemolysis as well as structural and morphological alterations in lymphocytes. Destruction of cell and nucleus membrane, changes in cell size, erythrocyte denucleation and reduced erythrocyte surface area were observed. Cadmium has caused erythrocyte hemolysis (29.30 %) and lymphocyte damage (92.10 %). Higher doses of lead resulted in greater damage to lymphocytes (63 %). Also, treatment with higher dose of lead produced a higher percentage of hemolyzed erythrocytes (19.20 %) in comparison to lower dose (9.90 %).

CONCLUSION

The toxicity of heavy metals leads to reduced maturation of the blast, which causes the appearance of immature cells in peripheral circulation and severe destruction of blood cell membranes. Erythrocyte hemolysis can lead to anemia, while lymphocyte damage can lead to lymphocytopenia.

Influence of silica nanoparticles on cadmium-induced cytotoxicity, oxidative stress, and apoptosis in human liver HepG2 cells

Extensive application of amorphous silica nanoparticles (Si NPs) and ubiquitous cadmium (Cd) may increase their chances of coexposure to humans. Studies on combined effects of Si NPs and Cd in human cells are very limited. We investigated the potential mechanism of toxicity caused by coexposure of amorphous Si NPs and Cd in human liver (HepG2) cells. Results showed that Si NPs were not toxic to HepG2. However, Cd induced significant toxicity in HepG2 cells. Interestingly, we observed that a noncytotoxic concentration of Si NPs potentiated the cytotoxicity of Cd in HepG2 cells. We further noticed that coexposure of Si NPs and Cd augmented oxidative stress evidenced by the generation of oxidants (reactive oxygen species, hydrogen peroxide, and lipid peroxidation) and depletion of antioxidants (glutathione level and antioxidant enzyme activity). Coexposure of Si NPs and Cd also augmented mitochondria-mediated apoptosis in HepG2 cells indicated by altered regulation of apoptotic genes (p53, bax, bcl-2, caspase-3, and caspase-9) along with reduced mitochondrial membrane potential. Interaction data indicated that Si NPs facilitate the cellular uptake of Cd due to its strong adsorption on the surface of Si NPs. Hence, Si NPs increased the bioaccumulation and toxicity of Cd in HepG2 cells. This study warrants further research to explore the potential mechanisms of combined toxicity of Si NPs and Cd in animal models.

Cadmium versus Lanthanum Effects on Spontaneous Electrical Activity and Expression of Connexin Isoforms Cx26, Cx36, and Cx45 in the Human Fetal Cortex

Electrical activity is important for brain development. In brain slices, human subplate neurons exhibit spontaneous electrical activity that is highly sensitive to lanthanum. Based on the results of pharmacological experiments in human fetal tissue, we hypothesized that hemichannel-forming connexin (Cx) isoforms 26, 36, and 45 would be expressed on neurons in the subplate (SP) zone. RNA sequencing of dissected human cortical mantles at ages of 17-23 gestational weeks revealed that Cx45 has the highest expression, followed by Cx36 and Cx26. The levels of Cx and pannexin expression between male and female fetal cortices were not significantly different. Immunohistochemical analysis detected Cx45- and Cx26-expressing neurons in the upper segment of the SP zone. Cx45 was present on the cell bodies of human SP neurons, while Cx26 was found on both cell bodies and dendrites. Cx45, Cx36, and Cx26 were strongly expressed in the cortical plate, where newborn migrating neurons line up to form cortical layers. New information about the expression of 3 "neuronal" Cx isoforms in each cortical layer/zone (e.g., SP, cortical plate) and pharmacological data with cadmium and lanthanum may improve our understanding of the cellular mechanisms underlying neuronal development in human fetuses and potential vulnerabilities.

Cadmium-Induced Testicular Toxicity in Mice: Subacute and Subchronic Route-Dependent Effects

This study aimed to compare Cd exposure by intraperitoneal (i.p.) and oral routes, evaluating the testicular subacute and subchronic effects. Adult male mice were separated into three groups subdivided according to the experimental period (7 and 42 days after Cd exposure: subacute and subchronic effects, respectively): one group received water and two groups received CdCl₂ (1.2 mg/kg i.p. and 24 mg/kg oral). The testicular concentration of essential minerals and Cd, activity of antioxidant enzymes and markers of oxidative stress, histology, and testicular histomorphometry were evaluated. The subacute effect of oral Cd showed reduced Fe concentration, while Ca and Cu increased in this route. The subchronic effect promoted decreasing in Mg in i.p. and oral routes, whereas Zn decreased only in the oral, and the Fe concentration did not change. SOD activity decreased in the oral subacute evaluation and in both pathways, i.p. and oral routes, in the subchronic evaluation, while GST activity increased, and MDA concentration decreased. Labeling of apoptotic cells was increased in the subacute and subchronic evaluation. Seminiferous epithelium degeneration, death of germ cells, and Leydig cell damages occurred in i.p. and oral routes. However, these damages were more intense in the oral route, mainly evaluating the subchronic effects. The results confirm that the severity of Cd-induced testicular injury depends on the pathway, as well as the duration of exposure.

The Protection of Selenium Against Cadmium-Induced Mitochondrial Damage via the Cytochrome P450 in the Livers of Chicken

Cadmium (Cd) is a heavy metal in natural environment and has extreme toxicity. Selenium (Se) has protective effect against heavy metal-induced injury or oxidative stress. Cytochrome P450 (CYP450) enzymes are a family of hemoproteins primarily responsible for detoxification functions. In order to investigate whether CYP450 is related to the damage of livers caused by Cd exposure, we chose forty-eight 28-day-old healthy Hailan cocks for four groups: control group, Se group, Cd group, and Se + Cd group. After 90-day treatment, euthanized for experiment. Based on an established subchronic Cd poisoning model in chicken, this experiment was designed to detect mitochondrial structure, malondialdehyde (MDA), glutathione (GSH), DNA and protein crosslink (DPC) and protein carbonyl (PCO) content, the CYP450 and b₅ contents, the aminopyrine-N-demethylase (AND), erythromycin N-demethylase (ERND), aniline 4-hydroxylase (AH) and NADPH-cytochrome C reducatase (CR) activities, and mRNA expression level in the livers. The present results indicated that the MDA content, PCO content, and DPC index in Cd group were higher than those observed in other three groups. Most of the mitochondrial structure is incomplete in Cd group. The contents of CYP450 and b₅ were decreased in Cd group. The activities of AND, ERND, AH, and CR got reduced after Cd exposure, as observed in CYP450 gene expression. Our results showed that CYP450 system was involved in the entire process of injury and protection. This research provides a comprehensive evaluation of the oxidative stress effects of Cd related to CYP450 in chicken.

Single and combined exposures of waterborne Cu and Cd induced oxidative stress responses and tissue injury in female rare minnow (Gobiocypris rarus)

Copper (Cu) and cadmium (Cd) are two kinds of abundant toxic metals in aquatic ecosystem. The present study evaluated the effects of waterborne Cu and Cd on oxidative stress responses and histological alterations in female rare minnow (Gobiocypris rarus). Fish were exposed for 7 days to: (i) control (no added Cu or Cd), (ii) waterborne Cu (39.2 μg L^-1), (iii) waterborne Cd (299.6 μg L^-1), and (iv) Cu and Cd in mixture (19.6 and 149.8 μg L^-1, respectively). Antioxidant enzyme activities and gene mRNA abundance in fish tissues (gills, liver, and ovaries) were induced by Cu and Cd exposures, both individually and in mixture, at day 1, but an asynchronous response was observed between most enzyme activities and gene mRNA abundance following 7 days exposure. Biochemical analysis and histological observation indicated that exposure to Cu and Cd, alone and in combination, caused evident damage to lipids and tissue structure in gills, liver and ovaries. Comparing with single Cu or Cd exposure, Cu and Cd co-exposure induced greater increase in the mRNA expression of most antioxidant genes and caused more severe lesions in fish tissues, which suggested that exposure to waterborne Cu and Cd in mixture might increase their individual toxicity. Furthermore, positive relationships between nuclear factor erythroid 2-related factor (Nrf2) expression and expression of manganese superoxide dismutase (Mn-SOD) and catalase (CAT) were also observed in the present study, which suggested that Cu or/and Cd induced expression of these antioxidant genes were might through activation of Nrf2.

Effects of chronic lead and cadmium exposure on the oriental river prawn (Macrobrachium nipponense) in laboratory conditions

During the past decade, the total population and overall reproductive performance of the oriental river prawn (Macrobrachium nipponense) in the Anzali international wetland and its basin rivers has been severely reduced. This seems to be caused by an increase in heavy metal pollution from industrial wastewaters. We investigated the effects of chronic levels of lead (Pb) and cadmium (Cd) on reproductive success, hemato-immunology, crustacean hyperglycemic hormone (cHH), Pb/Cd bioaccumulation and histopathology of hepatopancreas of oriental river prawn. The present study was separately carried out using four chronic treatments for Pb (0 (control), 0.024, 0.072 and 0.12 μM/l) and Cd (0 (control), 0.026, 0.053 and 0.08 μM/l) in experimental tanks during 60 days. The broodstock were fed by commercial shrimp diet, ad libitum, twice a day. The results revealed that reproductive activities ceased when Pb levels were 0.072 and 0.12 μM/l and also when Cd levels reached 0.08 μM/l. At 0.024 μM/l Pb, 0.026 and 0.053 μM/l Cd, the prawns showed initial reproductive activity but after spawning, the egg-clutches were found detached from the pleopods of the brood females. Hemato-immunology results showed that by increasing the Pb and Cd concentrations, large granular hemocyte (LGH) and cHH values also increased. However, small granular hemocyte (SGH) count was inversely affected. A significant increase in mortality (P < 0.05) was observed as both Pb and Cd concentrations increased. Histological observations are indicative of increased necrosis, lumen size, melanization, vacuolation and abnormal lumen shape, as the heavy metals concentrations increased. In conclusion, obtained results can help to elucidate effects of Pb and Cd on freshwater decapod crustaceans reproductive performance and related physiological parameters.

Subchronic Oral Cadmium Exposure Exerts both Stimulatory and Suppressive Effects on Pulmonary Inflammation/Immune Reactivity in Rats

OBJECTIVE

The aim of this study is to investigate the effects of oral cadmium (Cd) ingestion on the pulmonary immune response.

METHODS

Determination of Cd content in lungs and histopathological evaluation of the tissue was performed in rats following 30-day oral Cd administration (5 and 50 mg/L). Antioxidant enzyme defense (superoxide dismutase and catalase), cell infiltration, and production of tumor necrosis factor (TNF) and interferon (IFN)-γ, as well as the activity of myeloperoxidase (MPO), nitric oxide (NO), and various cytokines [interleukin (IL)-1β, IL-6, IL-10, and IL-17] were investigated.

RESULTS

Cd caused tissue damage and cell infiltration in the lungs, and this damage was more pronounced at higher doses. Cd deposition resulted in lung inflammation characterized by a dose-dependent IL-1β increase in lung homogenates, increased TNF levels at both doses, and IL-6 stimulation at low doses with inhibition observed at higher doses. Cd exerted differential effects on lung leukocytes isolated by enzyme digestion, and these effects were characterized by a lack of change in the production of reactive oxygen and nitrogen species, an inhibition of IL-1β and TNF, and stimulation of MPO and IFN-γ. The higher capacity of Cd-exposed lung cells to respond to the opportunistic pathogen Staphylococcus epidermidis was demonstrated in vitro.

CONCLUSION

The potential of ingested Cd to exert both proinflammatory and immunosuppressive effects on pulmonary tissue inflammation and immune reactivity highlights the complex immunomodulatory actions of this metal.

Sub-lethal effects of dimethoate alone and in combination with cadmium on biochemical parameters in freshwater snail, Galba truncatula

The objective of the present study was to evaluate the influence of the organophosphorus pesticide dimethoate and cadmium on biochemical parameters of a freshwater snail, Galba truncatula, in laboratory conditions. In 14 days, snails were exposed to 0, 100, 200, and 400 μg L^-1 of dimethoate and 0.0 and 1000 μg L^-1 of cadmium chloride. The results evidenced that dimethoate induces oxidative stress and alters biochemical parameters in freshwater snails. Cadmium also induced significant changes in biochemical parameters. The combination of the dimethoate and cadmium markedly increased the effects on G. truncatula. Dimethoate and cadmium mixture caused a decrease in Acetylcholinesterase (AChE), and Glucose-6-phosphate dehydrogenase (G6PDH) activities, glycogen, and total antioxidant capacity (TAN) levels, and increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), glutathione peroxidase (GPx), and catalase (CAT) activities, and malondialdehyde (MDA) level in exposed snails. The increased toxicity and bioaccumulation of cadmium after the exposure to the highest concentration of dimethoate indicates a synergistic effect leading to a reduced performance of the detoxification system in the snail. Dimethoate contributed to the bioconcentration of cadmium in snails and increased its toxic effects evidenced in biomarkers of oxidative stress and cell damage.

Soil properties and cultivars determine heavy metal accumulation in rice grain and cultivars respond differently to Cd stress

Field and pot experiments were conducted to evaluate the factors affecting heavy metal (HM) accumulation in rice grain and subsequently to explore their cultivar difference when exposed to Cd. Forty-seven paired soil and rice cultivar samples were collected from Jiangxi province, China. The contents of Cd, Cu, Zn, Pb, Cr, and Ni in soils and grains were determined. It showed that among these metals, Cr and Cd were the dominant contaminants in samples from the test areas, with 100.0% and 59.6% of all grain samples exceeding the maximum permissible concentration. Random forest analysis showed that soil pH, soil organic matter (SOM), Fe fraction and cultivar were four most important factors affecting HMs accumulation in grain. Based on bioconcentration factors, two cultivars with high Cd (HCd) accumulation ability and two cultivars with low Cd (LCd) accumulation ability in rice grain were chosen to explore their physiological and growth responses when exposed to 0, 50, 100 and 1000 μmol L^-1 Cd. The results showed that the Cd phytotoxicity is Cd level- and cultivar-dependent. The height and weight decreased, while Cd accumulation increased in shoot and root for the four rice cultivars with the increasing of Cd content. The HCd cultivars showed less membrane damage, higher superoxide dismutase (SOD) activity and higher Cd accumulation than that of LCd cultivars. In conclusion, heavy metal accumulation in rice grain is soil property- and cultivar-dependent. And different rice cultivars respond differently to Cd stress.

Limited oxidative stress in common carp (Cyprinus carpio, L., 1758) exposed to a sublethal tertiary (Cu, Cd and Zn) metal mixture

Analyzing effects of metal mixtures is important to obtain a realistic understanding of the impact of mixed stress in natural ecosystems. The impact of a one-week exposure to a sublethal metal mixture containing copper (4.8 μg/L), cadmium (2.9 μg/L) and zinc (206.8 μg/L) was evaluated in the common carp (Cyprinus carpio). To explore whether this exposure induced oxidative stress or whether defense mechanisms were sufficiently fitting to prevent oxidative stress, indicators of apoptosis (expression of caspase 9 [CASP] gene) and of oxidative stress (malondialdehyde [MDA] level and xanthine oxidase [XO] activity) were measured in liver and gills, as well as activities and gene expression of enzymes involved in antioxidant defense (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GPx], glutathione reductase [GR] and glutathione-S-transferase [GST]). The total antioxidative capacity (T-AOC) was also quantified. No proof of oxidative stress was found in either tissue but there was indication of apoptosis in the liver. CAT, GPx, GR and GST total activities were reduced after 7 days, suggesting a potential decrease of glutathione levels and risk of increased free radicals if the exposure would have lasted longer. There were no major changes in the total activities of antioxidant enzymes in the gills, but the relative expression of the genes coding for CAT and GR were triggered, suggesting a response at the transcription level. These results indicate that C. carpio is well equipped to handle these levels of metal pollution, at least during short term exposure.

A soybean-based diet modulates cadmium-induced vascular apoptosis

Cadmium (Cd) exposure has been associated with an increased risk of cardiovascular diseases. The diet is a modifiable source of protecting or damaging factors that may affect this risk. Herein we tested the hypothesis that a soybean-based diet (SBD) protects the vascular wall of the aorta against Cd-induced pro-inflammatory and pro-apoptotic effects. To test this hypothesis, we fed male Wistar rats for 60 days with a casein-based diet (CBD) or an SBD. These animals were also exposed to tap-water without (CBD-Co/SBD-Co) or with 15(CBD-15Cd/SBD-15Cd) or 100 (CBD-100Cd/SBD-100Cd) ppm of Cd. Inflammatory parameters (mRNAs and/or proteins) were measured in thoracic aorta tissue. These included inducible and endothelial nitric oxide synthases, cyclooxygenase-2, intracellular-adhesion molecule-1, and vascular cell-adhesion molecule-1. As pro-apoptotic parameters, we measured Bax and Bcl-2 mRNA/protein, as well as TUNEL positive cells in the aorta tissue. Compared to CBD-Co, inflammatory and apoptosis markers increased in the aorta with the concentration of Cd in the drinking water. These effects were not observed in either SBD-15Cd or SBD-100Cd, which were similar to CBD-Co. Cd content in serum and in aortas from animals fed CBD-Co/SBD-15Cd or CBD-Co/SBD-100Cd were similar suggesting that, if any, the effect of SBD is not due to changes in Cd bioaccumulation, but due to secondary effects linked to the composition of the dietary soybean flour. Our findings are consistent with a protective effect of an SBD against Cd-induced inflammation and apoptosis in the thoracic aorta in a rat model.

Protective effects of Ganoderma triterpenoids on cadmium-induced oxidative stress and inflammatory injury in chicken livers

Several studies have been conducted on liver damage caused by cadmium, but few on the protective effects of Ganoderma triterpenoids against liver damage due to cadmium. This experiment was designed to evaluate the protective effects of Ganoderma triterpenoids on the liver damage induced by cadmium in chickens. Eighty healthy seven-day-old Hyline male egg-laying chickens were randomly divided into four groups with 20 chickens in each group. All the experiments were carried out in triplicate. The control group (K group) was fed a basal diet, the Cadmium group (Cd group) was fed a basal diet with 140 mg/kg of CdCl₂, the Ganoderma triterpenoids treatment group (Cd + GT group) was fed with a full-fodder diet containing 140 mg/kg of CdCl₂ and 0.5 mL of Ganoderma triterpenoids solution (20 mg/mL), and the Ganoderma triterpenoids group (GT group) was fed a basal diet and 0.5 mL of Ganoderma triterpenoids solution (20 mg/mL). At the 20^th, 40^th, and 60^th days, fifteen chickens were randomly selected for euthanasia in each group. Livers were quickly removed and stored on ice. Some indicators, such as the cadmium content in the liver, antioxidant enzymes (superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px)) activities, malondialdehyde (MDA) content, and inflammatory factors(Tumor necrosis factor alpha (TNF-α), interleukin (IL-1β and IL-6)), heat shock protein (HSP27, 40, 60, 70, and 90) mRNA levels, and protein levels of heat shock proteins (HSP60, 70, and 90) were detected, and chicken liver pathology was taken for each group every 60 days. The results showed that cadmium exposure caused accumulation of cadmium in liver tissue, inhibited antioxidant enzyme activity, and increased MDA content, inflammatory cytokines (TNF-α IL-1β and IL-6), and heat shock protein (HSP27, 40, 60, 70, and 90) mRNA levels, and heat shock protein (HSP60, 70, and 90) levels, with severe tissue damage and inflammatory infiltrates. Ganoderma triterpenoids not only reduced the accumulation of cadmium in the chicken liver, but also significantly increased the activities of antioxidant enzymes which is inhibited by cadmium, reduced the content of MDA, mRNA expressions of inflammatory cytokines (TNF-α IL-1β and IL-6), and heat shock proteins (HSP27, 40, 60, 70, and 90), and protein levels of heat shock proteins (HSP60, 70, and 90). Simultaneously, pathological tissue sections showed that the pathological damage of the liver tissue was significantly reduced. The results showed that Ganoderma triterpenoids can significantly reduce the accumulation of cadmium in the liver of chicken, thereby reducing oxidative stress and inflammation.

Modulation of luminal L-alanine transport in proximal tubular cells of frog kidney induced by low micromolar Cd2+ concentration

The kidneys are recognized as a major target of cadmium-induced toxicity. However, all mechanisms that are involved in the early stages of cadmium nephrotoxicity, particularly considering low micromolar concentrations of cadmium ions (Cd²⁺) are still unknown. Therefore, the aim of this study was to investigate the effects of peritubular acute exposure to micromolar Cd²⁺ concentration (2.3 μmol/L) on the rapid depolarization and the rate of slow repolarization of peritubular membrane potential difference (PD), induced by luminal application of L-alanine in proximal tubular cells of frog kidney. The results showed that the luminal application of L-alanine rapidly depolarized the peritubular membrane PD of -42.00 ± 11.68 mV by 23.89 ± 4.15 mV with an average rate of slow repolarization of 5.64 ± 0.81 mV/min. Additionally, peritubular acute exposure to Cd²⁺ induced change in rapid depolarization of peritubular membrane PD of -53.33 ± 13.01 mV by 18.78 ± 3.31 mV (P < 0.01) after luminal application of L-alanine. Also, peritubular acute exposure to Cd²⁺ led to statistically significant decrease in the rate of slow repolarization of peritubular membrane PD (3.53 ± 0.35 mV/min; P < 0.05). In conclusion, these results suggest that peritubular acute exposure to low micromolar Cd²⁺ concentration decreased the rapid depolarization and the rate of slow repolarization of peritubular membrane PD induced by luminal application of L-alanine. This is followed by reduced luminal sodium-coupled transport of L-alanine and this change may be one of the possible mechanisms involved in the early stages of Cd²⁺-induced nephrotoxicity.

Chronic Cadmium Exposure Accelerates the Development of Atherosclerosis and Induces Vascular Dysfunction in the Aorta of ApoE-/- Mice

Cadmium exposure is related to cardiovascular diseases, including hypertension, atherosclerosis, increased oxidative stress, endothelial dysfunction, and specific biochemical changes induced by this metal. Thus, we aimed to investigate whether cadmium exposure induces endothelial dysfunction, accelerates atherosclerotic plaque formation in the aorta, and enhances oxidative stress in apolipoprotein E knockout (ApoE^-/-) mice. Experiments were performed in 14-week-old male wild-type and ApoE^-/- mice. ApoE^-/- mice received cadmium (CdCl₂ 100 mg/L in drinking water for 28 days) or vehicle (distilled water). After treatment, vascular reactivity to phenylephrine, acetylcholine, and sodium nitroprusside was analyzed using isolated aorta. Bone marrow cells were isolated to assess the production of nitric oxide and reactive oxygen and nitrogen species. ApoE^-/- cadmium-treated mice had higher cholesterol levels than non-exposed mice. Cadmium exposure decreased the vasodilatation response to acetylcholine in aortic ring of ApoE^-/- mice, though no changes in phenylephrine or sodium nitroprusside responses were observed. L-NAME reduced vasodilator responses to acetylcholine; this effect was lower in ApoE^-/- cadmium-treated mice, suggesting reduction in nitric oxide (NO) bioavailability. Moreover, in bone marrow cells, cadmium decreased cytoplasmic levels of NO and increased superoxide anions, hydrogen peroxide, and peroxynitrite in ApoE^-/- mice. Morphological analysis showed that cadmium exposure increased plaque deposition in the aorta by approximately 3-fold. Our results suggest that cadmium exposure induces endothelial dysfunction in ApoE^-/- mice. Moreover, cadmium increased total cholesterol levels, which may promote the early development of atherosclerosis in the aorta of ApoE^-/- mice. Our findings support the hypothesis that cadmium exposure might increase the risk of atherosclerosis.

Extract from Aronia melanocarpa L. Berries Prevents Cadmium-Induced Oxidative Stress in the Liver: A Study in A Rat Model of Low-Level and Moderate Lifetime Human Exposure to this Toxic Metal

The study investigated, in a rat model of low-level and moderate environmental exposure to cadmium (Cd; 1 or 5 mg Cd/kg diet, respectively, for 3 to 24 months), whether the co-administration of 0.1% extract from Aronia melanocarpa L. berries (AE) may protect against oxidative stress in the liver and in this way mediate this organ status. The intoxication with Cd, dose- and duration-dependently, weakened the enzymatic antioxidative barrier, decreased the concentrations of reduced glutathione and total thiol groups, and increased the concentrations of oxidized glutathione, hydrogen peroxide, xanthine oxidase, and myeloperoxidase in this organ. These resulted in a decrease in the total antioxidative status, increase in the total oxidative status and development of oxidative stress (increased oxidative stress index and malondialdehyde concentration) and histopathological changes in the liver. The administration of AE at both levels of Cd treatment significantly improved the enzymatic and nonenzymatic antioxidative barrier, decreased pro-oxidant concentration, and protected from the development of oxidative stress in the liver and changes in its morphology, as well as normalized the serum activities of liver enzymes markers. In conclusion, consumption of aronia products may prevent Cd-induced destroying the oxidative/antioxidative balance and development of oxidative stress in the liver protecting against this organ damage.

Dietary Cadmium Intake and Sources in the US

Cadmium (Cd) is a toxic heavy metal that can contribute to numerous diseases as well as increased mortality. Diet is the primary source of Cd exposure for most individuals, yet little is known about the foods and food groups that contribute most substantially to dietary Cd intake in the US. Therefore, the objective of this study was to estimate dietary Cd intake and identify major food sources of Cd in the US population and among subgroups of the population. Individuals aged 2 years and older from the National Health and Nutrition Examination Survey (NHANES) 2007⁻2012 were included in this study (n = 12,523). Cd intakes were estimated from two days of 24-h dietary recalls by matching intake data with the Cd database of the Food and Drug Administration (FDA)'s Total Diet Study 2006 through 2013. The average dietary Cd consumption in the population was 4.63 μg/day, or 0.54 μg/kg body weight/week, which is 22% of the tolerable weekly intake (TWI) of 2.5 μg/kg body weight/week. Greater daily Cd intakes were observed in older adults, males, those with higher income, higher education, or higher body mass index. The highest Cd intakes on a body weight basis were observed in children 10 years and younger (38% of TWI), underweight individuals (38% of TWI), and alcohol non-consumers (24% of TWI). The food groups that contributed most to Cd intake were cereals and bread (34%), leafy vegetables (20%), potatoes (11%), legumes and nuts (7%), and stem/root vegetables (6%). The foods that contributed most to total Cd intake were lettuce (14%), spaghetti (8%), bread (7%), and potatoes (6%). Lettuce was the major Cd source for Caucasians and Blacks, whereas tortillas were the top source for Hispanics, and rice was the top contributor among other ethnic subgroups including Asians. This study provides important information on the dietary Cd exposure of Americans, and identifies the groups with the greatest dietary Cd exposure as well as the major sources of dietary Cd among sociodemographic subgroups.

Estimation of dietary intake of cadmium from cadmium in blood or urine in East Asia

BACKGROUND AND AIM

Cadmium (Cd) is an ubiquitous environmental toxic pollutant. As daily foods are an almost exclusive source of exposure for general populations, it is of public health importance to know the level of dietary intake of cadmium (Cd-D). The purpose of this study is to examine whether Cd in blood (Cd-B) or urine (Cd-U) correlates with Cd-D in East Asia, and in case it is, whether it is possible to estimate Cd-D from Cd-B or Cd-U. It should be added that the measurement of Cd-D is quite hand-consuming in practice.

MATERIALS AND METHODS

Literature was retrieved for publication on Cd-B and Cd-U in combination with Cd-D. Twenty three data sets thus obtained for East Asia were subjected to regression analysis to investigate the possibility to estimate Cd-D from Cd-B or Cd-U.

RESULTS

In Japan and Korea, large correlation coefficients (p > 0.7) were observed between Cd-B and Cd-D, as well as between Cd-U and Cd-D. In China, the coefficient was >0.7 between Cd-B and Cd-D. Furthermore, correlation was significant for Cd-B and Cd-D, as well as Cd-U and Cd-D, when 19 sets for Japan, Korea and China were combined for analysis.

DISCUSSION

Major reasons for successful analysis may be predominant use of women-based data. Women have been less smoking than men in East Asia, and possible confounding effects of smoking on Cd exposure might be minimized.

CONCLUSION

Based on significant correlations, Cd-D can be estimated from Cd-B or Cd-U in East Asia.

Oral cadmium exposure affects skin immune reactivity in rats

Skin can acquire cadmium (Cd) by oral route, but there is paucity of data concerning cutaneous effects of this metal. Cd acquired by oral route can affect skin wound healing, but the effect of Cd on other activities involved in skin homeostasis, including skin immunity, are not explored. Using the rat model of 30-day oral administration of Cd (5 ppm and 50 ppm) in drinking water, basic aspects of immune-relevant activity of epidermal cells were examined. Dose-dependent Cd deposition in the the skin was observed (0.035 ± 0.02 µg/g and 0.127 ± 0.04 µg/g at 5 ppm and 50 ppm, respectively, compared to 0.012 ± 0.009 µg/g at 0 ppm of Cd). This resulted in skin inflammation (oxidative stress at both Cd doses and dose-dependent structural changes in the skin and the presence/activation of innate immunity cells). At low Cd dose inflammatory response (nitric oxide and IL-1β) was observed. Other inflammatory cytokines (IL-6 and TNF) response occurred at 50 ppm, which was increased further following skin sensitization with contact allergen dinitro-chlorobenzene (DNCB). Epidermal cells exposed to both Cd doses enhanced concanavalin A (ConA)-stimulated lymphocyte production of IL-17. This study showed for the first time the effect of the metal which gained access to the skin via gut on immune reactivity of epidermal cells. Presented data might be relevant for the link between dietary Cd and the risk of skin pathologies.

Association between dietary cadmium intake and early gastric cancer risk in a Korean population: a case-control study

PURPOSE

Foods such as grains and vegetables are the dominant sources of exposure to cadmium, which has been classified as a carcinogen by various public health agencies. Cadmium exposure is a growing concern due to its associations with numerous harmful health effects, including gastric cancer risk. The objective of this study was to investigate the association of dietary cadmium intake and the consumption of cadmium-contributing foods with early gastric cancer risk.

METHODS

A case-control study including 1245 subjects (cases, 415; controls, 830) was conducted in Korea. The dietary cadmium intake and the consumption of cadmium-contributing foods were assessed using a semi-quantitative food frequency questionnaire.

RESULTS

After adjustment for covariates, the gastric cancer risk was increased for participants in the highest tertile of cadmium intake [odds ratios (ORs) 1.33, 95% confidence intervals (95% CIs) 0.94-1.88], but there was no significance. Both female (ORs 2.71, 95% CIs 1.37-5.36) and male (ORs 1.63, 95% CIs 1.07-2.50) participants in the highest tertile of rice consumption had a higher gastric cancer risk than did those in the lowest tertile. Men in the highest tertile of crab consumption had a gastric cancer risk 2.23 times greater than that of men in the lowest tertile (ORs 2.23, 95% CIs 1.21-4.13), but a difference was not seen in women.

CONCLUSIONS

Future studies examining the causal effects of dietary cadmium intake and the consumption of cadmium-contributing foods on early gastric cancer risk in large-scale prospective cohorts are recommended.

Ameliorative Effects of Selenium on Cadmium-Induced Injury in the Chicken Ovary: Mechanisms of Oxidative Stress and Endoplasmic Reticulum Stress in Cadmium-Induced Apoptosis

Despite the well-established toxicity of cadmium (Cd) to animals and the ameliorative effects of selenium (Se), some specific mechanisms in the chicken ovary are not yet clarified. To explore the mechanism by which the toxicity effect of Cd is induced and explore the effect of supranutritional Se on Cd toxicity in female bird reproduction, forty-eight 50-day-old Isa Brown female chickens were divided randomly into four groups. Group I (control group) was fed the basic diet containing 0.2 mg/kg Se. Group II (Se-treated group) was fed the basic diet supplemented with sodium selenite (Na₂SeO₃), and the total Se content was 2 mg/kg. Group III (Se + Cd-treated group) was fed the basic diet supplemented with Na₂SeO₃; the total Se content was 2 mg/kg, and it was supplemented with 150 mg/kg cadmium chloride (CdCl₂). Group IV (Cd-treated group) was with the basic diet supplemented with 150 mg/kg CdCl₂. The Cd, estradiol (E2), and progestogen (P4) contents changed after subchronic Cd exposure in chicken ovarian tissue; subsequently, oxidative stress occurred and activated the endoplasmic reticulum (ER) pathway to induce apoptosis. Further, Se decreased the accumulation of Cd in ovarian tissue, increased the E2 and P4 contents, alleviated oxidative stress, and reduced apoptosis via the ER stress pathway. The present results demonstrated that Cd could induce apoptosis via the ER stress pathway in chicken ovarian tissue and that Se had a significant antagonistic effect. These results are potentially valuable for finding a strategy to prevent Cd poisoning.

Early-Life Exposure to Cadmium Triggers Distinct Zn-Dependent Protein Expression Patterns and Impairs Brain Development

The objective of this study was to determine if the brain development impairment induced by early-life exposure to cadmium (Cd) could result from changes in the expression pattern of distinct zinc (Zn)-dependent proteins. For this purpose, adult female rats receiving either tap water, Cd, Zn, or Cd + Zn in their drinking water during gestation and lactation periods were used. After birth, the male offspring were screened for locomotors and sensorial defects. At postnatal day 21 (PND 21), the male pups were sacrificed and their brains, liver, and plasma were taken for chemical, biochemical, and molecular analyses. Our results show that exposure to Cd significantly increased the metal accumulation and decreased Zn concentrations in the brain of male pups from Cd-treated mothers. Besides, Cd exposure reduced significantly the locomotor activity of the offspring in open-field test, the body weight, and the cranio-caudal length at PND21. Insulin-like growth factor-I (IGF-1) levels in the plasma and liver were also decreased in male pups from Cd-treated mothers. Cd-induced brain development disruption was accompanied by a significant increase of the superoxide dismutase (SOD) activity, induction of the metallothionein (MT) synthesis, and, at the molecular level, by an upregulation of Zrt-,Irt-related protein 6 (ZIP6) gene and a significant downregulation of the expression of the Zn transporter 3 (ZnT3) and brain-derived neurotrophic factor (BDNF) genes in the brain. No significant changes on the expression of genes encoding other Zn-dependent proteins and factors such as ZnT1, ZIP12, NF-κB, and Zif268. Interestingly, Zn supplementation provided a total or partial correction of the changes induced by the Cd exposure. These data indicated that changes in expression of ZnT3 and ZIP6 as well as alteration of other transcription factors, such as BDNF, or Zn-dependent proteins, such as SOD and MTs, in response to Cd exposure might be an underlying mechanism of Cd-induced brain development impairment.

Effects of dietary Pb and Cd and their combination on lysosomal and tissue-level biomarkers and histopathology in digestive gland of the land snail, Cantareus apertus (Born, 1778)

The present study was aimed at determining cell and tissue-level biomarkers and histopathological alterations in the green garden snail, Cantareus apertus (Born, 1778), exposed to different nominal dietary concentrations of Pb (25, 100 and 2500 mg Pb/kg), Cd (5, 10 and 100 mg Cd/kg) and their combination (25 mg Pb + 5 mg Cd/Kg, 100 mg Pb + 10 mg Cd/kg and 2500 mg Pb + 100 mg Cd/ kg) for 1 and 8 weeks. Lead and Cd exerted histopathological effects on the digestive gland in a dose-dependent manner and related to lysosomal and tissue-level biomarkers. The biological responses observed included digestive cell vacuolisation and numerical atrophy, calcium cell hydropic degeneration, excretory cell hypertrophy, inflammatory responses, blood vessel congestion, and disruption of the blood vessel wall and the interstitial connective tissue. Lysosomal enlargement and transient intracellular accumulation of neutral lipids and lipofuscins were also observed, together with alterations in the cell type composition and thinning of the digestive gland epithelium and with diverticular distortion. This response profile fits well with the biological effects reported after metal exposure in gastropods from other regions, as well as with data obtained in parallel studies dealing with metal bioaccumulation and intralysosomal accumulation, mortality, feeding, growth, oxidative stress and neurotoxicity exerted elicited by Pb, Cd and their mixture in green garden snails under the present experimental conditions. Consequently, C. apertus seems to be a suitable model species for the biomarker-based assessment of the biological effects of Pb and Cd, alone or in combinations, thus providing a challenging opportunity to advance in identifying suitable sentinel species for metal pollution biomonitoring and ecosystem health assessment in soil ecosystems in Northern Africa.

Oral administration of cadmium depletes intratesticular and epididymal iron levels and inhibits lipid peroxidation in the testis and epididymis of adult rats

Cadmium (Cd)-induced tissue injury depends on the accumulated Cd which differentially affects endogenous iron (Fe). To investigate this, adult rats were treated by oral gavage with Cd (50 mg/kg body wt.) once a week for 15, 30 and 60 days and sacrificed a day after last administration. After the 15th and 30th day of treatment, Cd had no effect on thiobarbituric acid reactive substances (TBARS) and endogenous Fe levels but exhibited anti-androgenic effects (p < 0.05) and caused histological damages. At day 60, Cd was accumulated by 156.30% and 364.77% above control values at concentrations that decreased endogenous Fe levels by 46.41% and 50.31% in the testis and epididymis respectively. The histological damages were characterized by decreased tubular diameter, damage to the epithelium leading to loss of tubular germ cells and absent of spermatozoa in the epididymal lumen. Although myeloperoxidase activities were increased, TBARS levels were found to decrease significantly at day 60 in the serum, testis and epididymis suggesting that the histological damages were not caused by lipid peroxidation. Furthermore, TBARS correlated negatively with Cd in the testis (r = -0.251, p < 0.05) and epididymis (r = -0.286, p < 0.05); Fe correlated positively with TBARS in the testis (r = +0.217, p < 0.05) and Cd correlated negatively with Fe in the testis (r = -0.461, p < 0.05) and epididymis (r = -0.109, p < 0.05). The antioxidant enzymes, superoxide dismutase and glutathione peroxidase were also decreased in the gonads after 60 days Cd treatment. Overall, anti-androgenic effects and histo-pathological changes are early indicators of direct effects of Cd and occur before decrease in TBARS which is secondarily related to the modifying of Fe contents.

The Antagonistic Effect of Selenium on Cadmium-Induced Damage and mRNA Levels of Selenoprotein Genes and Inflammatory Factors in Chicken Kidney Tissue

Selenium (Se) is a necessary trace mineral in the diet of humans and animals. Cadmium (Cd) is a toxic heavy metal that can damage animal organs, especially the kidneys. Antagonistic interactions between Se and Cd have been reported in previous studies. However, little is known about the effects of Se against Cd toxicity and on the mRNA levels of 25 selenoprotein genes and inflammatory factors in chicken kidneys. In the current study, we fed chickens with a Se-treated, Cd-treated, or Se/Cd treated diet for 90 days. We then analyzed the mRNA expression of inflammatory factors (including prostaglandin E synthase (PTGES), nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2)) and 25 selenoprotein genes (Gpx1, Gpx2, Gpx3, Gpx4, Txnrd1, Txnrd2, Txnrd3, Dio1, Dio2, Dio3, SPS2, Sepp1, SelPb, Sep15, Selh, Seli, Selm, Selo, Sels, Sepx1, Selu, Selk, Selw, Seln, Selt). The results demonstrated that Cd exposure increased the Cd content in the chicken kidneys, renal tubular epithelial cells underwent denaturation and necrosis, and the tubules became narrow or disappeared. However, Se supplementation reduced the Cd content in chicken kidneys and induced normal development of renal tubular epithelial cells. In addition, we also observed that Se alleviated the Cd-induced increase in the mRNA levels of inflammatory factors and ameliorated the Cd-induced downtrend in the mRNA levels of 25 selenoprotein genes in chicken kidneys.

Impact of oral cadmium intoxication on levels of different essential trace elements and oxidative stress measures in mice: a response to dose

The study evaluated the effect of oral intoxication of cadmium and the possible causes of oxidative stress and its preferential accumulation in different organs as well as sub-sequential effects in mice. Twenty-four Swiss albino male mice were divided into three groups viz., normal control group without cadmium chloride (CdCl₂), whereas a daily dose of 0.5 and 1.2 mg of CdCl₂ was orally administered for a period of a week to dose group 1 (DG-1) and dose group 2 (DG-2), respectively. A significant increase in the severity of cadmium toxicity was observed in animals as evidenced by aggravation in liver enzymes viz., serum alanine aminotransferase and aspartate transaminase, whereas lower levels of antioxidative stress markers in liver and kidney tissues of treated mice were observed as compared to normal control group. A significant depletion of calcium levels in liver tissues of DG-1 (217.36 ± 1.73 μg/g of wet tissues) and DG-2 (186.41 ± 1.56 μg/g of wet tissues) groups, along with Cd accumulation, was observed. To summarize, the current study would increase our understanding with respect to dose-dependent absorption of Cd and its toxicity led to mortality as well as adverse health effects in the body of mice. Graphical abstract ᅟ.

Dose-Dependent Differential Effects of In Vivo Exposure of Cadmium on Myometrial Activity in Rats: Involvement of VDCC and Ca2+-Mimicking Pathways

Present study was undertaken to study the effect of 28-days exposure of female adult rats to cadmium (Cd) in drinking water @ 3, 10 and 30 parts per million (ppm) on myometrial responsiveness to different spasmogens and unravel the possible mechanism of alterations in myometrial activity. Cadmium and Ca²⁺ levels in blood and uterus were measured by atomic absorption spectroscopy while isometric tension in myometrial strips was measured using data acquisition system-based physiograph. Dose-dependent increase in levels of cadmium was observed in both blood and uterus while calcium was increased only in the uterus as compared to those in control. Significant increase in absolute tension and mean integral tension along with non-significant increase in frequency of myometrial contraction was observed in rats of Cd-treated groups. As compared to the control, cadmium decreased and increased the effects of calcium chloride, 80 mM KCl, histamine (0.1 μM) and oxytocin (10^-2 IU/ml) in lower-dose (3 ppm) and higher-dose groups (10 and 30 ppm), respectively. Cadmium potentiated and inhibited the relaxant response to phenylephrine in myometrium of rats at lower-dose (3 ppm) and highest-dose (30 ppm) Cd-treated groups, respectively. Results of our study revealed that Cd accumulates in the myometrium of rats and alters its responsiveness to oxytocin, histamine, 80 mM KCl, calcium chloride and phenylephrine, and these effects are differentially mediated depending on levels of exposure possibly through voltage-dependent calcium channel (VDCC) and Ca²⁺-mimicking pathways.

Dietary Intake of Cadmium, Lead and Mercury and Its Association with Bone Health in Healthy Premenopausal Women

The bone is one of the relevant target organs of heavy metals, and heavy metal toxicity is associated with several degenerative processes, such osteoporosis and bone mineral alterations, that could lead to fractures. We aimed to study a presumed relationship between bone density, evaluated by quantitative bone ultrasound (QUS), dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) and the dietary intake of cadmium, lead and mercury in healthy premenopausal women. A total of 158 healthy, non-smoking, premenopausal women were incorporated into the study. A validated food frequency questionnaire (FFQ) was administered to assess intake during the preceding seven days. The median predicted dietary cadmium intake among the 158 women studied was 25.29 μg/day (18.62–35.00) and 2.74 μg/kg body weight/week (b.w./w) (1.92–3.83). Dietary lead intake was 43.85 μg/day (35.09–51.45) and 4.82 μg/kg b.w./w (3.67–6.13). The observed dietary mercury intake was 9.55 μg/day (7.18–13.57) and 1.02 μg/kg b.w./w (0.71–1.48). Comparisons, in terms of heavy metal intake, showed no significant results after further adjusting for energy intake. No statistically significant correlations between heavy metal intake and the QUS, DXA and pQCT parameters were observed. Levels of dietary exposure of cadmium, lead and mercury were mostly within the recommendations. We did not find associations between the QUS, DXA and pQCT parameters and the dietary intake of the studied heavy metals in healthy premenopausal women.

Involvement of Zn Depletion in Cd-Induced Toxicity on Prenatal Bone Formation in Rat

This study explored the potential toxicity of Cd on the Zn bone depletion in prenatal bone formation. Female rats received either tap water, Cd, Zn, or Cd + Zn in their drinking water during gestation, and some markers of bone formation were studied in their fetuses removed at the 20th day of pregnancy (GD20). Cd exposure induced maternal hypozincemia and Zn depletion in the femur of the fetuses. A striking inhibition of bone formation in fetuses, expressed by decreases in femur length, width, and area, by the shortening of diaphysis, and by a decrease in length and area of distal and proximal proliferative zones, was observed in fetuses from Cd-exposed mothers. At the molecular level, Cd caused upregulation of MT-1 and ZIP2 genes and significantly depressed the expression of the ZnT5, colα1, osteocalcin, and ALP genes in the femur. Interestingly, Zn treatment ameliorated the Cd-induced maternal hypozincemia and femoral changes and partially restored the normal histomorphometry of the femur. These results suggest that the observed toxic effects of Cd are, at least in part, mediated by the disruption of maternal Zn metabolism during pregnancy leading to Zn depletion and thus to perturbation of prenatal bone formation.

Physiological and transcriptome response to cadmium in cosmos (Cosmos bipinnatus Cav.) seedlings

To date, several species of Asteraceae have been considered as Cd-accumulators. However, little information on the Cd tolerance and associated mechanisms of Asteraceae species Cosmos bipinnatus, is known. Presently, several physiological indexes and transcriptome profiling under Cd stress were investigated. C. bipinnatus exhibited strong Cd tolerance and recommended as a Cd-accumulator, although the biomasses were reduced by Cd. Meanwhile, Cd stresses reduced Zn and Ca uptake, but increased Fe uptake. Subcellular distribution indicated that the vacuole sequestration in root mainly detoxified Cd under lower Cd stress. Whilst, cell wall binding and vacuole sequestration in root co-detoxified Cd under high Cd exposure. Meanwhile, 66,407 unigenes were assembled and 41,674 (62.75%) unigenes were annotated in at least one database. 2,658 DEGs including 1,292 up-regulated unigenes and 1,366 down-regulated unigenes were identified under 40 μmol/L Cd stress. Among of these DEGs, ZIPs, HMAs, NRAMPs and ABC transporters might participate in Cd uptake, translocation and accumulation. Many DEGs participating in several processes such as cell wall biosynthesis, GSH metabolism, TCA cycle and antioxidant system probably play critical roles in cell wall binding, vacuole sequestration and detoxification. These results provided a novel insight into the physiological and transcriptome response to Cd in C. bipinnatus seedlings.

Initial autophagic protection switches to disruption of autophagic flux by lysosomal instability during cadmium stress accrual in renal NRK-52E cells

The renal proximal tubule (PT) is the major target of cadmium (Cd2+) toxicity where Cd2+ causes stress and apoptosis. Autophagy is induced by cell stress, e.g., endoplasmic reticulum (ER) stress, and may contribute to cell survival or death. The role of autophagy in Cd2+-induced nephrotoxicity remains unsettled due to contradictory results and lack of evidence for autophagic machinery damage by Cd2+. Cd2+-induced autophagy in rat kidney PT cell line NRK-52E and its role in cell death was investigated. Increased LC3-II and decreased p62 as autophagy markers indicate rapid induction of autophagic flux by Cd2+ (5-10 µM) after 1 h, accompanied by ER stress (increased p-PERK, p-eIF2α, CHOP). Cd2+ exposure exceeding 3 h results in p62/LC3-II accumulation, but diminished effect of lysosomal inhibitors (bafilomycin A1, pepstatin A +E-64d) on p62/LC3-II levels, indicating decreased autophagic flux and cargo degradation. At 24 h exposure, Cd2+ (5-25 µM) activates intrinsic apoptotic pathways (Bax/Bcl-2, PARP-1), which is not evident earlier (≤6 h) although cell viability by MTT assay is decreased. Autophagy inducer rapamycin (100 nM) does not overcome autophagy inhibition or Cd2+-induced cell viability loss. The autophagosome-lysosome fusion inhibitor liensinine (5 μM) increases CHOP and Bax/Bcl-2-dependent apoptosis by low Cd2+ stress, but not by high Cd2+. Lysosomal instability by Cd2+ (5 μM; 6 h) is indicated by increases in cellular sphingomyelin and membrane fluidity and decreases in cathepsins and LAMP1. The data suggest dual and temporal impact of Cd2+ on autophagy: Low Cd2+ stress rapidly activates autophagy counteracting damage but Cd2+ stress accrual disrupts autophagic flux and lysosomal stability, possibly resulting in lysosomal cell death.

Successive Onset of Molecular, Cellular and Tissue-Specific Responses in Midgut Gland of Littorina littorea Exposed to Sub-Lethal Cadmium Concentrations

Cadmium (Cd) is one of the most harmful metals, being toxic to most animal species, including marine invertebrates. Among marine gastropods, the periwinkle (Littorina littorea) in particular can accumulate high amounts of Cd in its midgut gland. In this organ, the metal can elicit extensive cytological and tissue-specific alterations that may reach, depending on the intensity of Cd exposure, from reversible lesions to pathological cellular disruptions. At the same time, Littorina littorea expresses a Cd-specific metallothionein (MT) that, due to its molecular features, expectedly exerts a protective function against the adverse intracellular effects of this metal. The aim of the present study was, therefore, to assess the time course of MT induction in the periwinkle’s midgut gland on the one hand, and cellular and tissue-specific alterations in the digestive organ complex (midgut gland and digestive tract) on the other, upon exposure to sub-lethal Cd concentrations (0.25 and 1 mg Cd/L) over 21 days. Depending on the Cd concentrations applied, the beginning of alterations of the assessed parameters followed distinct concentration-dependent and time-dependent patterns, where the timeframe for the onset of the different response reactions became narrower at higher Cd concentrations compared to lower exposure concentrations.

Single-scan rest/stress imaging with 99mTc-Sestamibi and cadmium zinc telluride-based SPECT for hyperemic flow quantification: A feasibility study evaluated with cardiac magnetic resonance imaging

Introduction

We aimed to evaluate whether the hyperemic myocardial blood flow (MBF) can be estimated using cadmium zinc telluride (CZT)-based single-photon emission computed tomography (SPECT) cameras with a single, rapid rest/stress dynamic scan. Dynamic contrast-enhanced (DCE) cardiac magnetic resonance imaging (MRI) was used as a reference modality for flow measurement.

Materials and methods

The proposed protocol included both the rest and stress acquisitions within a 24-min scan. Patients were first injected with 99mTc-Sestamibi at the resting state. Sixty minutes after the first injection, the subject was positioned via scintigraphy, after which the list-mode data acquisition was initiated and continued for 24 minutes. Five minutes after data acquisition was initiated, a stressed state was induced via dipyridamole infusion, after which a second dose of 99mTc-Sestamibi was injected. Dynamic SPECT images were reconstructed for all subjects, who also underwent T1-weighted cardiac DCE-MRI performed on days other than those of the SPECT studies. MBF values were estimated for the rest and stress MRI studies, and for the stress portion of the SPECT study. The SPECT-measured hyperemic MBF was compared with the MR-measured hyperemic MBF and coronary flow reserve (CFR), based on the regions of interest.

Results

A total of 30 subjects were included in this study. The hyperemic MBF estimated from SPECT showed a strong correlation with the MR-measured hyperemic MBF (r² = 0.76) and a modest correlation with the MR-measured CFR (r² = 0.56). Using MR-measured CFR <1.3 as a cutoff for coronary stenosis, we found that the SPECT-measured hyperemic MBF served as a useful clinical index with 94% sensitivity, 90% specificity, and 93% accuracy.

Conclusions

Hyperemic MBF can be measured with a rapid, single-scan rest/stress study with CZT-based SPECT cameras.

Progressive silencing of the zinc transporter Zip8 (Slc39a8) in chronic cadmium-exposed lung epithelial cells

Cadmium (Cd), a non-essential metal, stealthily enters the cells by utilizing the essential metal importing pathways. The zinc transporters Zip8, Zip14, and divalent metal transporter 1 (Dmt1) are now emerging as several important metal transporters involved in cellular Cd incorporation and their expressions have been shown to be down-regulated in several Cd-resistant (CdR) cell lines, however, the involvement of these transporters during the development of Cd-resistance in lung cells is unclear. In this study, we therefore check the expression of these metal transporters in our previously established rat lung epithelial cells (LECs) and show that the level of Zip8 is progressively silenced when LECs are adapted to increasing concentrations of CdCl2 (from 1 to 20 μM). Subsequent measurement of the cellular Cd content indicated that CdR LECs exhibit a marked decrease of Cd accumulation, possibly due to the loss of Zip8 expression. We investigate the possibility that epigenetic silencing of the Zip8 gene by DNA hypermethylation is involved in the down-regulation of Zip8 expression. CdR LECs show a higher mRNA level of DNA methyltransferase 3b (Dnmt3b) than parental cells. Treatment of CdR LECs with 5-aza-2'-deoxycytidine, an inhibitor of DNA methyltransferases, reverted the expression of Zip8 and sensitivity to Cd in these cells, indicating the critical role of Zip8 for Cd import. Taken together, our results demonstrate that the progressive silencing of Zip8 expression is involved in the acquisition of resistance against Cd in lung cells, representing an adaptive survival mechanism that resists Cd-induced cytotoxicity.