Utilization of Lead Nitrate to Enhance the Impact of Hydroxamic Acids on the Hydrophobic Aggregation and Flotation Behavior of Cassiterite.

Lead nitrate (LN) is frequently employed as an activator in the flotation of cassiterite using hydroxamic acids as the collectors. This study investigated the effect of LN on the hydrophobic aggregation of cassiterite when benzohydroxamic acid (BHA), hexyl hydroxamate (HHA), and octyl hydroxamate (OHA) were used as the collectors through micro-flotation, focused beam reflectance measurement (FBRM) and a particle video microscope (PVM), zeta potential, and the extended DLVO theory. Micro-flotation tests confirmed that LN activated the flotation of cassiterite using the hydroxamic acids as collectors. Focused beam reflectance measurement (FBRM) and a particle video microscope (PVM) were used to capture in situ data on the changes in size distribution and morphology of cassiterite aggregates during stirring. The FBRM and PVM image results indicated that the addition of LN could promote the formation of hydrophobic aggregates of fine cassiterite, when BHA or HHA was used as the collector, and reduce the dosage of OHA needed to induce the formation of hydrophobic aggregates of cassiterite. The extended DLVO theory interaction energies indicated that the presence of LN could decrease the electrostatic interaction energies (Vedl) and increase the hydrophobic interaction energies (Vhy) between cassiterite particles, resulting in the disappearance of the high energy barriers that existed between the particles in the absence of LN. Thus, cassiterite particles could aggregate in the presence of LN when BHA, HHA, or a low concentration of OHA was used as the collector.

Validation of the Lead Care II System in Cape vultures (Gyps coprotheres) in comparison to ICP-MS using pure standards.

Lead toxicosis remains a concern in raptors, especially following feeding on carcasses sourced from hunting. Rapid diagnosis of lead exposure and easy field monitoring is desirable. The LeadCareII analytical system, validated for rapid diagnoses of lead toxicity in humans, has been described as a useful evaluation system in various species. For this study we attempt to validate the LeadCareII system in the Cape Vulture (CV) (Gyps coprotheres). Blood samples from CV housed under captive conditions and low background lead exposure, were pooled and spiked with known concentrations of a lead standard (0-60 µg/dL). Samples were analyzed by the LeadCareII system and by ICP-MS. The final results showed that despite good linearity the LeadCareII system underestimated lead concentrations by up to 50 %. While the results can be corrected by the derived equation, this is not supported due to the large underestimations evident. The reason for the underestimation is presently unknown.

How will Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) and lead (Pb) exposure interact in the cardiovascular system?

The combined effects of lead exposure and the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and how they cause cardiovascular dysfunction are examined in this viewpoint manuscript. Lead was picked as a representative environmental contaminant because it has been studied extensively for more than 40 years, while SARS-CoV-2 illustrates the unpredictability of a new infectious agent that can quickly increase the environmental burden on communities. Given that this interaction represents a plausible combined exposure for many people, it is crucial to discuss how it might happen at a mechanistic level. SARS-CoV-2 causes the coronavirus disease 2019 (COVID-19), which can spread by contact and respiratory droplets. One may be exposed to lead and SARS-CoV-2 simultaneously depending on their living situation. Uncertainty exists regarding the consequences of this exposure on cardiovascular disease and its underlying processes. This paper aims to investigate these mechanisms and provide potential causes behind them. The interaction of lead with SARS-CoV-2 and its effects on the cardiovascular system are likely caused by direct damage, the promotion of reactive oxygen species (ROS) production, oxidative stress, and inflammation. In particular, the stimulation of nuclear factor kappa B (NF-B), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF) were all identified as potentially important pathways. Blood clotting, cytokine storm cycle development, and increased hypoxia may also be the results of this. In summary, the effects on the immune system, coagulation, the renin-angiotensin-aldosterone system, and cardiac contractility were the four primary areas identified.

High lead contamination in Mother's breastmilk in Bihar (India): Health risk assessment of the feeding children.

Lead poisoning in the recent times has caused serious health threats in the exposed human population. It is estimated that about 815 million people are exposed to lead poisoning worldwide and in India total 275 million children are exposed to blood lead contamination. The present study was carried outed in 6 districts of Bihar to know the extent of lead exposure in the children through their mother's breastmilk. The biological samples such as breastmilk, mother's urine, child's urine, and mother's blood samples were collected for quantitative lead estimation. Moreover, the selected household water sources (handpump) and the food consumed by the individuals-wheat, rice and potato samples were also collected for lead quantification. The study reveals that the breastmilk had high lead content in 92% of the samples (highest value 1309 µg/L), in blood presence of lead was observed in 87% studied samples (highest value 677.2 µg/L). In mother's urine the highest lead value was 4168 µg/L (62%) and in child's urine the highest value was 875.4 µg/L (62%) respectively of the studied samples. Moreover, in the studied food samples, wheat had lead content in 45% the studied samples (highest value 7910 µg/kg). In rice in 40% of the studied samples (highest value 6972 µg/kg) and in potato 90% of the studied samples (highest value = 13786 µg/kg) were found with elevated lead content respectively. The hazard quotient (HQ) and the cancer risk (CR) for lead contamination was very much higher in mothers followed by their children. The entire study indicated that lead exposure through food (wheat, rice and potato) has reached the mother's breastmilk and from their it has reached their child's body. This could cause serious hazards in the exposed children causing serious neurological damages, low IQ, low memory, and low mental growth in them. Therefore, a strategic action is required to control the present problem.

A multi-year heavy metal analysis of 72 dark chocolate and cocoa products in the USA.

Introduction: Contamination of cocoa containing products, such as dark chocolate, with heavy metals including lead, cadmium and arsenic has been reported in the US. However, a formal exploration into the significance of this contamination, nor multi-year trends in the degree or scope remain unresolved. Methods: From 2014 to 2022, 72 consumer cocoa-containing products were purchased and analyzed for heavy metal contamination with lead (Pb), cadmium (Cd), and arsenic (As) in 4 distinct cohorts (2014, 2016, 2019, 2022). The thresholds used to assess heavy metal contamination were set to Prop 65 maximum allowable dose levels (MADLs) of 0.5 mcg/day, 4.1 mcg/day, 10 mcg/day for Pb, Cd, and As, respectively. Results and discussion: Our analysis reports that 43, 35, and 0% of the products tested exceed Prop 65 MADLs for heavy metal concentrations, respectively, of Pb, Cd, and As, while 97.2% (70 of 72) fall below US FDA IRL limits established for Pb. Median concentrations of each metal tested were lower than even the conservative Prop 65 MADLs, indicating a potentially large effect of product outliers. This indicates that heavy metal contamination-in more than half of products tested-may not pose any appreciable risk for the average person when consumed as a single serving; however, consuming some of the products tested, or more than one serving per day in combination with non-cocoa derived sources heavy metals, may add up to exposure that would exceed the Prop 65 MADLs. Notably, "organic" products were significantly more likely to demonstrate higher levels of both Cd and Pb.

Different Short-Chain Fatty Acids Unequally Modulate Intestinal Homeostasis and Reverse Obesity-Related Symptoms in Lead-Exposed High-Fat Diet Mice.

Our previous study showed that heavy metal lead (Pb) exposure exacerbates high-fat-diet (HFD)-induced metabolic damage and significantly depletes the gut microbiota-derived metabolite short-chain fatty acid (SCFA) levels. However, it remains unclear whether SCFA is a key metabolite involved in accelerating adverse consequences after Pb exposure. In this study, we explored the effects of exogenous supplementation of acetate, propionate, and butyrate on a metabolic disorder model in Pb-exposed HFD mice. We found that three SCFA interventions attenuated glycolipid metabolism disorders and liver damage, with butyrate performing the best effects in improving obesity-related symptoms. All three SCFA promoted the abundance of Muribaculaceae and Muribaculum, acetate specifically enriched Christensenellaceae, Blautia, and Ruminococcus, and butyrate specifically enriched Parasutterella, Rikenella, Prevotellaceae_UCG-001, and Bacteroides, which contributed to the positive promotion of SCFA production forming a virtuous cycle. Besides, butyrate inhibited Gram-negative bacteria Escherichia-Shigella. All of these events alleviated the intestinal Th17/Treg imbalance and inflammatory response through crosstalk between the G protein-coupled receptor (GPR)/histone deacetylase 3 (HDAC3) and lipopolysaccharide (LPS)/toll-like receptors 4 (TLR4)/nuclear factor κ-B (NF-κB) pathways and ultimately improved the intestinal barrier function. SCFA further upregulated the monocarboxylate transporter 1 (MCT1) and GPR43/adenosine 5'-monophosphate-activated protein kinase (AMPK) pathways to inhibit hepatic lipid accumulation. Overall, SCFA, especially butyrate, is an effective modulator to improve metabolic disorders in obese individuals exposed to heavy metals by targeting gut microecology.

Lead-212/Bismuth-212 In Vivo Generator Based on Ultrasmall Silver Telluride Nanoparticles.

Radionuclide therapy employing alpha emitters holds great potential for personalized cancer treatment. However, certain challenges remain when designing alpha radiopharmaceuticals, including the lack of stability of used radioconjugates due to nuclear decay events. In this work, ultrasmall silver telluride nanoparticles with a core diameter of 2.1 nm were prepared and radiolabeled with lead-212 using a chelator-free method with a radiolabeling efficiency of 75%. The results from the in vitro radiochemical stability assay indicated a very high retention of bismuth-212 despite the internal conversion effects originating from the decay of 212Pb. To further evaluate the potential of the nanoparticles, they were radiolabeled with indium-111, and their cell uptake and subcellular distribution were determined in 2D U87 cells, showing accumulation in the nucleus. Although not intentional, it was observed that the indium-111-radiolabeled nanoparticles induced efficient tumor cell killing, which was attributed to the Auger electrons emitted by indium-111. Combining the results obtained in this work with other favorable properties such as fast renal clearance and the possibility to attach targeting vectors on the surface of the nanoparticles, all well-known from the literature, these ultra-small silver telluride nanoparticles provide exciting opportunities for the design of theragnostic radiopharmaceuticals.

Evaluation of radiation dose to the lens in interventional cardiology physicians before and after dose limit regulation changes.

In response to the International Commission on Radiological Protection (ICRP), which lowered the lens equivalent dose limit, Japan lowered the lens dose limit from 150 mSv/year to 100 mSv/5 years and 50 mSv/year, with this new rule taking effect on April 1, 2021. DOSIRIS® is a dosimeter that can accurately measure lens dose. Herein, we investigated lens dose in interventional cardiology physicians one year before and after the reduction of the lens dose limit using a neck dosimeter and lens dosimeter measurements. With an increase in the number of cases, both personal dose equivalent at 0.07 mm [Hp(0.07), neck dosimeter] and personal dose equivalent at 3 mm depth [Hp(3), lens dosimeter] increased for most of the physicians. The Hp(3) of the lens considering the shielding effect of the Pb glasses using lens dosimeter exceeded 20 mSv/year for two of the 14 physicians. Protection from radiation dose will become even more important in the future, as these two physicians may experience radiation dose exceeding 100 mSv/5 years. The average dose per procedure increased, but not significantly. There was a strong correlation between the neck dosimeter and lens dosimeter scores, although there was no significant change before and after the lens dose limit was lowered. This correlation was particularly strong for physicians who primarily treated patients. As such, it is possible to infer accurate lens doses from neck doses in physicians who primarily perform diagnostics. However, it is desirable to use a dosimeter that can directly measure Hp(3) because of the high lens dose.

Trends in mercury, lead and cadmium concentrations in 27 European streams and rivers: 2000-2020.

Temporal trends for concentrations of mercury (Hg), lead (Pb) and cadmium (Cd) were evaluated from year 2000 to 2020 in 20 (Hg), 23 (Pb) and 11 (Cd) watercourses in remote forest catchments in Europe. Decreasing trends were observed in 15% (Hg), 39% (Pb) and 45% (Cd) of the watercourses during the period of evaluation. Decreasing trends were mainly observed between 2000 and 2005 for Hg and between 2000 and 2015 for Pb and Cd. For the last five years of the studied time period (2015-2020), more watercourses showed significant increasing, rather than decreasing Hg, Pb and Cd trends. This was interpreted as a legacy effect of metals still retained in catchment soils. The overall negative trends during the earlier part of the study period were likely driven by declining deposition of metals over Europe, especially for Pb and Cd. Other changes related to metal transport and chemistry may have contributed to the observed trends as well, including recovery from acidification and the ongoing browning of surface waters at northern latitudes. Here we found that organic carbon could explain the seasonal variation in Hg and Pb, but was not related the interannual trends. This study highlights the need for long-term monitoring and robust statistical methods that can detect multidirectional, long-term change in water chemistry.

[Cerebellar ferroptosis of hypertension mice following lead exposure].

OBJECTIVE: Exploring the changes in cerebellar ferroptosis in hypertensive mice after lead exposure. METHODS: Twenty-five healthy C57 male mice were selected to construct a hypertensive model by intraperitoneal injection of angiotensin II(Ang II) at a concentration of 0.05 mg/kg for 7 consecutive days. After a systolic blood pressure of 140 mmHg, 20 hypertensive mice were randomly divided into a hypertensive control group and a hypertensive lead exposure group. Twenty C57 mice with normal blood pressure were randomly divided into a blood pressure normal control group and a blood pressure normal lead exposure group. The mice in the normal blood pressure control group and the hypertensive control group drank water freely. Mice in the lead exposure group with normal blood pressure and the lead exposure group with hypertension drank lead acetate water containing 250 mg/L. Ang II was injected intraperitoneally every two days in the hypertensive control group and hypertensive lead exposed group mice. Each group of mice was poisoned for 12 weeks. Using open field experiments and balance beam experiments to detect motor dysfunction in mice. Using a reagent kit to detect the levels of divalent iron(Fe~(2+)), malondialdehyde(MDA), and glutathione(GSH) in the cerebellum of different groups of mice. Western blot was used to determine the protein expression of member 11 of the solute carrier family 7(SLC7A11), glutathione peroxidase 4(GPX4), nuclear receptor coactivator 4(NCOA4), microtubule associated protein 1 light chain 3B(LC3B), and ferritin heavy chain 1(FTH1) in mouse cerebellar tissue. RESULTS: The result of the open field experiment showed that the activity distance(1013.04 cm) of mice in the hypertensive lead exposure group was significantly lower than that of the hypertensive control group(1351.18 cm) and the lead exposure group with normal blood pressure(1287.35 cm). And the lead exposure group with hypertension also extended the time through the balance beam, which was 29.40 seconds(P<0.05). In addition, the Fe~(2+)content in the cerebellum of mice in the hypertensive lead exposure group was 3.33 µmol/g prot, which was 1.54 times that of the hypertensive control group and 1.14 times that of the lead exposure group with normal blood pressure. The MDA content was 4.71 nmol/mg prot, higher than that of the hypertensive control group and the lead exposure group with normal blood pressure. The GSH content was 5.36 µmol/g prot, lower than that of the hypertensive control group and the lead exposure group with normal blood pressure(P<0.05). Western blot result showed that compared with the hypertensive control group and the lead exposure group with normal blood pressure, the protein expression of SLC7A11 and GPX4 in the hypertensive lead exposure group was significantly reduced(P<0.05). In addition, compared with the control group with normal blood pressure, the expression of NCOA4 and LC3B proteins in the cerebellum of mice in the hypertension control group and lead exposure group with normal blood pressure increased, while the expression of FTH1 protein decreased(P<0.05). The expression of NCOA4 and LC3B proteins in the hypertensive lead exposure group was higher than that in the hypertensive control group and the lead exposure group with normal blood pressure, while the expression of FTH1 protein decreased(P<0.05). CONCLUSION: Lead exposure can exacerbate iron death in the cerebellar tissue of hypertensive mice, and iron autophagy may be involved in its occurrence and development.

Natural and synthetic 5-(3'-indolyl)oxazoles: Biological activity, chemical synthesis and advanced molecules.

5-(3'-Indolyl)oxazole moiety is a privileged heterocyclic scaffold, embedded in many biologically interesting natural products and potential therapeutic agents. Compounds containing this scaffold, whether from natural sources or synthesized, have demonstrated a wide array of biological activities. This has piqued the interest of synthetic chemists, leading to a large number of reported synthetic approaches to 5-(3'-indolyl)oxazole scaffold in recent years. In this review, we comprehensively overviewed the different biological activities and chemical synthetic methods for the 5-(3'-indolyl)oxazole scaffold reported in the literatures from 1963 to 2024. The focus of this study is to highlight the significance of 5-(3'-indolyl)oxazole derivatives as the lead compounds for the lead discovery of anticancer, pesticidal, antimicrobial, antiviral, antioxidant and anti-inflammatory agents, to summarize the synthetic methods for the 5-(3'-indolyl)oxazole scaffold. In addition, the reported mechanism of action of 5-(3'-indolyl)oxazoles and advanced molecules studied in animal models are also reviewed. Furthermore, this review offers perspectives on how 5-(3'-indolyl)oxazole scaffold as a privileged structure might be exploited in the future.

Oxidative response to cadmium and lead accumulations in the tissues of blue swimming crabs Portunus pelagicus from the Trang Province coastline, Southern Thailand.

OBJECTIVE: Metals have been reported to alter the oxidative status of both redox-active and redox-inactive metals accompanying oxidative stress induction. In aquatic ecosystems, metal contamination is regarded as serious pollutants and bioaccumulation, especially when aquatic seafood products are involved, which results in human risk. The blue swimming crab Portunus pelagicus is a highly popular crab species for consumption as seafood in Thailand. The meat parts and the hepatopancreas (HP) together with gonad are consumed and in high demand. Therefore, the present study aimed to investigate bioaccumulation of cadmium (Cd) and lead (Pb) along with tissue oxidative responses in P. pelagicus. METHODS: Sixty-seven samples of P. pelagicus were obtained from small-scale fishers along the coastline of Trang Province. Bioaccumulation of Cd and Pb and oxidative response in gill, muscle, and HP + gonad were evaluated. RESULT: Cadmium and Pb accumulation levels were highest in the HP and gonad, followed by the gill and then muscle, indicating that Cd and Pb have a high affinity to be concentrated in the HP and gonad. An organ-specific oxidative response to Cd and Pb accumulation was demonstrated in which Cd significantly activated superoxide dismutase (SOD) activity in the gills and muscle tissue, while Pb significantly activated the SOD activity only in the HP and gonad. Only Cd accumulation in gill tissue represented a significant activation of lipid peroxidation, as indicated by the malondialdehyde level. CONCLUSION: This study implied that P. pelagicus exhibits an "adaptive stage" in the oxidative response of tissue due to metal accumulation. Additionally, the data presented here further indicate that the consumption of only the meat parts and removal of the HP and gonad would reduce human exposure to metal toxicity.

Bioinspired Microgel-Loaded Smart Membrane Filtration with the Thermo- and Ion-Dual Responsive Water Gate for Selective Lead(II) Separation.

Lead (Pb2+) is a ubiquitous pollutant. Membrane filtration represents one of the most common water treatment methods, but nanofiltration and ultrafiltration require high transmembrane pressure, while microfiltration has larger pore sizes than ions, making them unfavorable for direct ion removal at low cost. Selective and direct separation of Pb2+ via membrane filtration at high efficiency without sacrificing the flux of clean water still remains challenging. Herein, inspired by the Pb2+-tolerable oleander that enriches and prevents Pb2+ in roots from permeating the plant body, a smart Pb2+-adsorptive filtration membrane with a temperature- and ion-tunable water gate was prepared by loading dual-responsive poly(N-isopropylacrylamido-co-acrylamido-benzo-18-crown-6) (PNB-5-20) microgels onto a commercial membrane. The PNB-5-20 microgel exhibits pronounced temperature-responsive swelling/deswelling (hydrodynamic diameter, 650-330 nm) with a volume phase transition temperature (VPTT) at ∼33 °C. Moreover, the microgel shows a high Pb2+-adsorption capacity (qmax, 85.4 mg/g) and good selectivity (distribution coefficient Kd ∼ 1000 mL/g) thanks to its complexation with the crown ether, as well as good Pb2+ responsiveness, having the VPTT positively shifted to 40 °C in the presence of Pb2+ with enhanced swelling behaviors. Functionalized with PNB-5-20, the smart membrane integrates Pb2+ detection, adsorption, and tunable water drainage in a single device. The membrane selectively recognizes Pb2+ in the polluted water with the gates in membrane pores switching from "open" to "closed", intercepting and adsorbing Pb2+ with water permeation reduced. Once purified, the gates can be "re-opened" by increasing the temperature. Construction of such an intelligent membrane filtration device with a tunable water gate and excellent Pb2+ recognition and adsorption performance will greatly simplify the remediation of Pb2+-polluted water.

Spatial and temporal variation in the prevalence of illegal lead shot in reared and wild mallards harvested in England.

The use of lead shotgun ammunition for shooting wildfowl has been restricted in England since 1999, but surveys finding lead shot in harvested birds show compliance with regulations has been low. Following the announcement in 2020 of a voluntary transition from lead to non-lead shot by UK shooting organizations, we investigated spatiotemporal variation in the composition of ammunition used for shooting mallards Anas platyrhynchos. We collected 176 harvested mallards during the 2021/22 shooting season and analyzed recent shot extracted from carcasses to determine shot composition. Using a separate collection of ducks of known provenance, we used stable isotope analysis as a means of differentiating captive-reared from wild mallards. This allowed us to understand how compliance might vary between driven game shooters, characterized by shooting birds that are flushed over a stationary line of shooters, and who primarily harvest captive-reared and released ducks, and wild duck shooters. Of 133 mallards containing recent shot, 92 (69%) had been illegally shot with lead. Analysis of this and five comparable surveys between 2001 and 2019 indicates regional and temporal variation in lead shot presence in England. In the North West and West Midlands, the likelihood of mallards containing lead shot decreased significantly over time, but no other regions showed significant changes. The use of non-lead shot types varied over time, with increases in steel shot use approximately matched by declines in bismuth shot. Mallards likely to be reared were more likely to have been shot with lead (75%) than those likely to be wild (48%). This suggests the use of lead shot is more frequent among driven game shooters than wild duck shooters. In England in 2021/22, most mallards continued to be shot with lead, suggesting that neither legislation nor voluntary approaches have been effective in substantially reducing illegal use of lead shot.

Childhood lead exposure increases the risk of attention-deficit-hyperactivity disorder: A meta-analysis.

Environmental lead exposure has been a much-discussed risk factor for the development of ADHD for decades. However, due to methodological shortcomings, the existing research on this topic is highly inconsistent. We will attempt to clarify this question by performing a meta-analysis based on a systematic literature search until February 2024 including different databases such as Pubmed and Google Scholar. The effects of environmental lead exposure were synthesized by odds ratios. A random effects model was deployed with a Paule-Mandel estimator using Hedges' invariance weighting. In addition, we carried out sensitivity analyses to examine the robustness of effects, including the detection of outliers, publication bias, p-hacking and moderating variables. In total, 14 studies with 14 effect sizes were included which had investigated the effects of lead exposure on the development of ADHD. The analyses were based on a final sample size of N = 7618 with n = 2554 ADHD cases (33,53 %) and n = 5064 healthy controls (66.47 %). Our results show that lead exposure was significantly associated with a higher risk of ADHD development. Regression analyses demonstrated that increased age of participants and increased lead significantly enhanced the risk of ADHD. Summing up we present novel results concerning the relationship between environmental lead exposure and the development of ADHD, while discussing underlying pathomechanisms as well as limitations. Finally, we provide recommendations for future studies and public health policies.

Evaluation and novel treatment in a case of refractory small bowel-small bowel intussusception.

Small bowel into small bowel intussusception can present with symptoms similar to those observed in patients with more common small bowel into large bowel intussusception. In most cases, intussusceptions isolated to the small bowel are self-limited and less likely to result in bowel ischemia. Nonetheless, any patient with recurrent intussusception should be evaluated to assess location and for the presence of a pathologic lead point. We report a patient with recurrent small bowel into small bowel intussusception who underwent a comprehensive evaluation that revealed lymphoid hyperplasia in the absence of a pathologic lead point. His symptoms resolved after a dose of oral dexamethasone.

Demyelination and Impaired Oligodendrogenesis in the Corpus Callosum Following Lead Exposure.

The corpus callosum is an oligodendrocyte-enriched brain region, replenished by newborn oligodendrocytes from oligodendrocyte progenitor cells (OPCs) in subventricular zone (SVZ). Lead (Pb) exposure has been associated with multiple sclerosis, a disease characterized by the loss of oligodendrocytes. This study aimed to investigate effects of Pb exposure on oligodendrogenesis in SVZ and myelination in corpus callosum. Adult female mice were used for a disproportionately higher prevalence of multiple sclerosis in females. Acute Pb exposure (one ip-injection of 27 mg Pb/kg as PbAc2 24 hrs before sampling) caused mild Pb accumulation in corpus callosum. Ex vivo assay using isolated SVZ tissues collected from acute Pb-exposed brains showed a diminished oligodendrogenesis in SVZ-derived neurospheres compared to controls. In vivo subchronic Pb exposure (13.5 mg Pb/kg by daily oral gavage 4 wks) revealed significantly decreased newborn BrdU+/MBP+ oligodendrocytes in corpus callosum, suggesting demyelination. Mechanistic investigations indicated decreased Rictor in SVZ OPCs, defective self-defense pathways, and reactive gliosis in corpus callosum. Given the interwined pathologies between multiple sclerosis and Alzheimers's disease, effect of Pb on myelination was evalued in AD-modeled APP/PS1 mice. Myelin MRI on mice following chronic exposure (1000 ppm Pb in drinking water as PbAc2 for 20 wks) revealed a profound demyelination in corpus callosum compared to controls. Immunostaining of choroid plexus showed diminished signalling molecule (Klotho, OTX2) expressions in Pb-treated animals. These observations suggest that Pb caused demyelination in corpus callosum, likely by disrupting oligodendrogenesis from SVZ OPCs. Pb-induced demyelination represents a crucial pathogenic pathway in Pb neurotoxicity, including multiple sclerosis.

Origin of Dopant-Carrier Exchange Coupling and Excitonic Zeeman Splitting in Mn2+-Doped Lead Halide Perovskite Nanocrystals.

Low-dimensional metal halide perovskites have unique optical and electrical properties that render them attractive for the design of diluted magnetic semiconductors. However, the nature of dopant-exciton exchange interactions that result in spin-polarization of host-lattice charge carriers as a basis for spintronics remains unexplored. Here, we investigate Mn2+-doped CsPbCl3 nanocrystals using magnetic circular dichroism spectroscopy and show that Mn2+ dopants induce excitonic Zeeman splitting which is strongly dependent on the nature of the band-edge structure. We demonstrate that the largest splitting corresponds to exchange interactions involving the excited state at the M-point along the spin-orbit split-off conduction band edge. This splitting gives rise to an absorption-like C-term excitonic MCD signal, with the estimated effective g-factor (geff) of ca. 70. The results of this work help resolve the assignment of absorption transitions observed for metal halide perovskite nanocrystals and allow for a design of new diluted magnetic semiconductor materials for spintronics applications.