Metal bashing: iron deficiency and manganese overexposure impact on peripheral nerves

Presence of micronuclei and nuclear abnormalities in Caracara (Polyborus) plancus living in an airport area in southern Brazil

The aviation sector is believed to be responsible for considerable environmental damage attributed to emission of a large number and amount of pollutants. Airports are often surrounded by forest fragments and humid areas that attract birds of prey and hence may potentially serve as useful bioindicators. The aim of the present study was to examine genotoxic potential in raptors exposed to airport pollution using the micronucleus (MN) test and morphological changes as evidenced by bilateral symmetry. This investigation was conducted at Salgado Filho International Airport of Porto Alegre - RS as well as in private and zoological breeding grounds. The presence of metals was measured in the blood cells of the collected birds. Seventeen birds (Caracara (Polyborus) plancus) were used in this study 11 from exposed and 6 from non-exposed group. The nuclear alterations clearly indicate that organisms exposed to airport pollution exhibited a significantly higher frequency of genetic damage compared to non-exposed birds. Further, manganese and chromium were detected exclusively in the blood of the exposed group. In contrast, the analysis of bilateral symmetry did not detect any significant morphologic differences between the two groups. Therefore, data indicate that blood genotoxic stress occurs in birds of prey living in civil aviation areas as evidenced by MN frequency increase and presence of manganese and chromium.

Fungicides as a risk factor for the development of neurological diseases and disorders in humans: a systematic review

Although studies show that pesticides, especially insecticides, may be toxic to humans, publications on the neurological effects of fungicides are scarce. As fungicides are used widely in Brazil, it is necessary to gather evidence to support actions aimed at safely using of these chemicals. We investigated through a systematic review of publications on the use of fungicides and consequences of exposure related to nervous system diseases or neurological disorders in humans. The protocol review was registered on PROSPERO and followed the guidelines of the PRISMA-Statement. As far as it is known, there is no apparent systematic review in the literature on this topic. The search was comprised of the following databases: PubMed; Web of Science; Scopus and EMBASE, using groups of Mesh terms and strategies specific to each database. Thirteen articles were selected for this review. Regarding the substances analyzed in the studies, some reported the use of fungicides in general, without separating them by type, while others summarized the categories of all pesticides by their function (insecticides, herbicides, fungicides, etc.) or chemical class (dithiocarbamate, dicarboximide, inorganic, etc.). However, most of the articles referred to fungicides that contain the metal manganese (Mn) in their composition. As for neurological disorders, articles addressed Parkinson's disease (PD), neurodevelopmental outcomes, extrapyramidal syndrome resembling PD, cognitive disorders, depression, neural tube defects, motor neurone disease, and amyotrophic lateral sclerosis. Most investigations pointed to exposure to fungicides, mainly maneb and mancozeb, leading to the development of at least one neurological disease, which suggests the need for further multicentric clinical trials and prospective studies for greater clarity of the research problem.

Iron role paradox in nerve degeneration and regeneration

Iron accumulates in the neural tissue during peripheral nerve degeneration. Some studies have already been suggested that iron facilitates Wallerian degeneration (WD) events such as Schwann cell de-differentiation. On the other hand, intracellular iron levels remain elevated during nerve regeneration and gradually decrease. Iron enhances Schwann cell differentiation and axonal outgrowth. Therefore, there seems to be a paradox in the role of iron during nerve degeneration and regeneration. We explain this contradiction by suggesting that the increase in intracellular iron concentration during peripheral nerve degeneration is likely to prepare neural cells for the initiation of regeneration. Changes in iron levels are the result of changes in the expression of iron homeostasis proteins. In this review, we will first discuss the changes in the iron/iron homeostasis protein levels during peripheral nerve degeneration and regeneration and then explain how iron is related to nerve regeneration. This data may help better understand the mechanisms of peripheral nerve repair and find a solution to prevent or slow the progression of peripheral neuropathies.

Association between blood heavy metal concentrations and skin cancer in the National Health and Nutrition Examination Survey, 2011-2018

We aimed to evaluate the associations between blood cadmium (Cd), mercury (Hg), lead (Pb), manganese (Mn), and selenium (Se) concentrations and skin cancer. This cross-sectional study was based on National Health and Nutritional Examination Survey (NHANES) data. A binomial logistic regression model was used to analyze the associations between exposure to the metal elements and the risk of skin cancer, and further stratified analyses were conducted by gender, age, body mass index, ethnicity, education, smoking, alcohol drinking, and hypertension. A total of 16,034 participants were included. After fully adjusting for multivariate, the odd ratio (OR)[95% confidence interval (95% CI)] values for skin cancer in those with blood Mn concentrations in the second, third, and fourth quartiles were 0.52 (0.33-0.82), 0.57 (0.36-0.9), and 0.56 (0.35-0.89), respectively, compared with those in the lowest quartile. The ORs (95% CI) for each 1-SD increment in log-transformed values for blood Mn concentrations were 0.79 (0.66-0.94), 0.8 (0.66-0.97), and 0.79 (0.66-0.96), respectively. A significant association between blood Hg and skin cancer was also observed in participants who drank alcohol, with a corresponding OR (95% CI) of 2.61 (1.37-5.00) (p interaction = 0.006). Our study indicated that a higher blood Mn concentration was negatively associated with skin cancer, and blood Hg was positively associated with skin cancer in participants who drank alcohol.

The Role of Dietary Nutrients in Peripheral Nerve Regeneration

Peripheral nerves are highly susceptible to injuries induced from everyday activities such as falling or work and sport accidents as well as more severe incidents such as car and motorcycle accidents. Many efforts have been made to improve nerve regeneration, but a satisfactory outcome is still unachieved, highlighting the need for easy to apply supportive strategies for stimulating nerve growth and functional recovery. Recent focus has been made on the effect of the consumed diet and its relation to healthy and well-functioning body systems. Normally, a balanced, healthy daily diet should provide our body with all the needed nutritional elements for maintaining correct function. The health of the central and peripheral nervous system is largely dependent on balanced nutrients supply. While already addressed in many reviews with different focus, we comprehensively review here the possible role of different nutrients in maintaining a healthy peripheral nervous system and their possible role in supporting the process of peripheral nerve regeneration. In fact, many dietary supplements have already demonstrated an important role in peripheral nerve development and regeneration; thus, a tailored dietary plan supplied to a patient following nerve injury could play a non-negotiable role in accelerating and promoting the process of nerve regeneration.

Sevoflurane anesthesia during pregnancy in mice induces cognitive impairment in the offspring by causing iron deficiency and inhibiting myelinogenesis

Maternal anesthetic exposure during pregnancy is associated with an increased risk of cognitive impairment in offspring. The balance of cerebral iron metabolism is essential for the development of brain tissue. Iron deficiency affects the myelinogenesis and nerve tissue development, especially in fetus or infant, which has a key role in cognitive function. We aimed to investigate whether maternal sevoflurane (Sev) exposure caused cognitive impairment in offspring through inducing iron deficiency and inhibiting myelinogenesis. Pregnant mice (gestation stage day 14) were treated with 2% Sev for 6 h. Cognitive function of offspring mice was determined by the Morris water maze and Context fear conditioning test. Iron levels were assayed by Perl's iron staining and synchrotron imaging. Hippocampus and cortex tissues or cerebral microvascular endothelial cells of offspring mice (postnatal day 35) were harvested and subjected to Western blot and/or immunhistochemistry to assess ferritin, transferrin receptor 1(TfR1), Ferroportin-1 (FpN1), myelin basic protein (MBP), tight junction protein ZO-1, occludin, and claudin-5 levels. Beginning with postnatal day 30, the offspring were treated with iron therapy for 30 days, and the indicators above were tested. Our results showed Sev dramatically decreased the iron levels of brain and impaired cognitive function in offspring mice. Sev decreased the expression of heavy chain ferritin (FtH), light chain ferritin (FtL), MBP, ZO-1, occludin, claudin-5, and FpN1, and increased TfR1 in hippocampus and cortex or cerebral microvascular endothelial cells of offspring mice, indicating that Sev caused the iron deficiency and impaired the myelinogenesis in the brain of offspring. Interestingly, iron therapy prompted the myelinogenesis and improved impaired cognitive function at postnatal day 60. Our research uncovered a new mechanism which showed that iron deficiency induced by Sev and myelin formation disorder due to decreased iron of brain may be an important risk factor for cognitive impairment in offspring. It was necessary for offspring to be supplied iron supplement whose mother suffered exposure to sevoflurane during pregnancy.