Evaluation of divalent metal transporter 1 (DMT1) (rs224589) polymorphism on blood lead levels of occupationally exposed individuals

Lead exposure at the feto-maternal interface: a cause for concern for fetal membrane trophoblasts

The integrity of fetal membranes enables biological functions that protect the fetus and maintain the pregnancy. Any compromise in fetal membrane function can predispose a pregnant woman to prelabor rupture of the membranes (pPROMs) and subsequently to preterm birth (PTB). Epidemiologic data suggest that lead exposure during pregnancy is one of several risk factors associated with PTB and pPROM. This heavy metal can cross placental and fetal membrane barriers, disrupting homeostasis in these tissues. Autophagy contributes to the maintenance of fetal membrane homeostasis during gestation, and dysfunctional autophagy is associated with pPROM. In this study, we determined the mechanistic impact of lead-induced cellular changes, autophagy, senescence, and inflammation in chorion trophoblast cells (CTCs) and amnion epithelial cells (AECs) of the fetal membranes. Lead exposure in CTCs induced autophagy dysfunction (increase in LC3B-II), augmented senescence (increased SA-β-galactosidase activity), and increased the release of inflammation. In AECs, lead exposure did effect autophagy, senescence, nor inflammation. The differential changes observed in CTCs and AECs after exposure to high lead concentrations may promote the weakening of fetal membranes and contribute to preterm rupture.

Concentrations and influencing factors of 17 elements in placenta, cord blood, and maternal blood of women from an e-waste recycling area

BACKGROUND

The effects of prenatal element exposure on mothers and fetuses have generated concern. Profiles of trace and toxic elements in biological material are urgently desired, especially for women who reside near e-waste recycling facilities. The aim of this study was to investigate elements concentrations in placenta, cord blood, and maternal blood of women and to evaluate the influencing factors.

METHODS

A group of 48 women from an e-waste recycling site and a group of 31 women from a non-e-waste recycling site were recruited. Basic characteristics were collected by questionnaire and the concentrations of 17 elements in placenta, cord blood, and maternal blood samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Finally, the generalized linear model regression analysis (GLM) was used to test the association between element concentrations and possible factors.

RESULTS

Compared to the control group, the exposed group had significantly elevated cadmium (Cd), zinc (Zn), nickel (Ni), and antimony (Sb) in placenta, and higher lead (Pb) in maternal blood and cord blood (P<0.05). Sb concentration in maternal blood was significantly lower than in the control group (P<0.05). GLM analysis showed that element concentrations were mainly associated with maternal age [chromium (Cr), iron (Fe), selenium (Se), cobalt (Co), mercury (Hg) in placenta, copper (Cu) in maternal blood], education (Se, Sb in placenta), family income (Cu in maternal blood and Ni in placenta), passive smoking [Cu and Zn in placenta, Pb in maternal blood], and e-waste contact history (Hg in cord blood, Cu, Zn, and Cd in maternal blood).

CONCLUSIONS

Women in the e-waste recycling area had higher toxic element levels in the placenta and blood samples. More preventive measures were needed to reduce the risk of element exposure for mothers and fetuses in these areas.

Olfactory tract/bulb metal concentration in Manganese-exposed mineworkers

BACKGROUND

Manganese (Mn) is an essential micronutrient as well as a well-established neurotoxicant. Occupational and environmental exposures may bypass homeostatic regulation and lead to increased systemic Mn levels. Translocation of ultrafine ambient airborne particles via nasal neuronal pathway to olfactory bulb and tract may be an important pathway by which Mn enters the central nervous system.

OBJECTIVE

To measure olfactory tract/bulb tissue metal concentrations in Mn-exposed and non-exposed mineworkers.

METHODS

Using inductively coupled plasma-mass spectrometry (ICP-MS), we measured and compared tissue metal concentrations in unilateral olfactory tracts/bulbs of 24 Mn-exposed and 17 non-exposed South African mineworkers. We used linear regression to investigate the association between cumulative Mn exposures and olfactory tract/bulb Mn concentration.

RESULTS

The difference in mean olfactory tract/bulb Mn concentrations between Mn-exposed and non-Mn exposed mineworkers was 0.16 µg/g (95% CI -0.11, 0.42); but decreased to 0.09 µg/g (95% CI 0.004, 0.18) after exclusion of one influential observation. Olfactory tract/bulb metal concentration and cumulative Mn exposure suggested there may be a positive association; for each mg Mn/m3-year there was a 0.05 µg/g (95% CI 0.01, 0.08) greater olfactory tract/bulb Mn concentration overall, but -0.003 (95% CI -0.02, 0.02) when excluding the three influential observations. Recency of Mn exposure was not associated with olfactory tract/bulb Mn concentration.

CONCLUSIONS

Our findings suggest that Mn-exposed mineworkers might have higher olfactory tract/bulb tissue Mn concentrations than non-Mn exposed mineworkers, and that concentrations might depend more on cumulative dose than recency of exposure.

Structural Characterization of Zinc-Sucrose Complex and Its Ability to Promote Zinc Absorption in Caco-2 Monolayer Cells and Mice

Sucrose emerges as a metal-ion chelating agent with excellent stability that may increase metal-ion absorption. This study aimed to characterize the structure of zinc-sucrose complex and investigate its ability to promote zinc absorption in Caco-2 monolayer cells and mice. Based on the results of the inductively coupled plasma emission spectrometer (ICP-ES), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared spectroscopy (FT-IR), it can be inferred that zinc and sucrose were chelated at a 1:1 ratio, with the hydroxyl groups playing a significant role. The Caco-2 monolayer cell model revealed that zinc-sucrose complex increased the amount of zinc uptake, retention, and transport in a dose- and time-dependent manner. Through the upregulation of genes and proteins for ZIP4, MT1, and DMT1, treatment with zinc-sucrose complex improved the proportion of absorbed zinc utilized for transport compared to ZnCl2 (26.21 ± 4.96 versus 8.50 ± 1.51%). Pharmacokinetic analysis of mice confirmed the zinc absorption-promoting effect of zinc-sucrose complex, as indicated by the considerably higher serum zinc level (4.16 ± 0.53 versus 2.56 ± 0.45 mg/L) and intestinal ZIP4, MT1, and DMT1 gene expression than ZnCl2. Further treatment of different zinc channel inhibitors and CETSA demonstrated the direct interaction of zinc-sucrose complex with ZIP4 protein and ZIP4-mediated cellular transport of zinc-sucrose complex. These findings provide a novel insight into the zinc absorption-promoting mechanism of zinc-sucrose complex, which could be used as an ingredient in functional foods to treat zinc deficiency.

Derivation of benchmark doses for male reproductive toxicity in a subacute low-level Pb exposure model in rats

The objectives of the study were to simulate low-level Pb exposure scenario in an animal model and to examine reproductive adverse effects. Based on obtained data, we have performed Benchmark dose (BMD)-response modelling. Male Wistar rats were randomized in seven groups (n = 6): one control and six treated with: 0.1, 0.5, 1, 3, 7, and 15 mg Pb/kg body weight, daily for 28 days by oral gavage. The rats were sacrificed and the blood and testes were used for further analysis of testosterone levels in serum, testicular essential metal levels and histological analysis. The Pb treatment led to a dose-dependent decrease of serum testosterone levels with a negative trend (BMDI 0.17-6.13 mg Pb/kg). Increase of Zn (dose-dependent, BMDI 0.004-19.7 mg Pb/kg) and Cu and a decrease of Mn testicular levels were also detected with unscathed histology of the testes. The presented results might be used in further evaluation of the point of departure in human health risk assessment for Pb.

Asymptomatic Lead Poisoning in a Pediatric Patient

Lead poisoning is a harmful condition, potentially resulting in irreversible impairments in neurocognition and behavioral development in the pediatric population. Rarely, life-threatening complications may ensue. We report a case of an asymptomatic four-year-old patient presenting with elevated lead levels (74.7 µg/dL) detected on routine blood lead screening at a well-child examination. The patient has a history significant for atopic disease, namely atopic dermatitis, seasonal allergic rhinitis, and food allergies. Overall, the asymptomatic nature of lead poisoning warrants judicious screening in the pediatric population due to the potential for neurologic complications.

Iron metabolism: pathways and proteins in homeostasis

Iron is essential to human survival. The biological role and trafficking of this trace essential inorganic element which is also a potential toxin is constantly being researched and unfolded. Vital for oxygen transport, DNA synthesis, electron transport, neurotransmitter biosynthesis and present in numerous other heme and non-heme enzymes the physiological roles are immense. Understanding the molecules and pathways that regulate this essential element at systemic and cellular levels are of importance in improving therapeutic strategies for iron related disorders. This review highlights the progress in understanding the metabolism and trafficking of iron along with the pathophysiology of iron related disorders.