SciCombinator

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Journal: Toxicology letters

28

The relation between Lead (Pb) and iron (Fe) becomes increasingly concerned because they are both divalent metals that are absorbed by the same intestinal mechanism, and Pb exposure and Fe deficiency in the developmental brain, as well as Fe overload in the aged brain, can cause cognitive deficits. However, the interaction between Pb exposure and Fe status in the brain has not been established. Therefore, in the current study, we examined the effects of maternal ingestion of Pb in drinking water during gestation and lactation on the Fe status and the expression of divalent metal transporter 1 (DMT1) and ferroportin 1 (FP1) in the brain of offspring. The offspring were followed through old age, with measurements taken at postnatal week 3, 41 and 70. Pb exposure increases the Fe content in the old-aged rats' brain, Which might be not subjected to DMT1 mediating, but may be associated with the decrease expression of FP1. Furthermore, the effect of Pb on FP1 expression is regulated at transcriptional and posttranscriptional levels. The perturbation in Fe homeostasis may contribute to the neurotoxicology consequences induced by Pb exposure, and FP1 may play a role in Pb-induced Fe cumulation in the brain.

Concepts: Hepcidin, Old age, Lead poisoning, Ferroportin, Metal, Iron, DMT1, Human iron metabolism

28

Esters of phthalic acid are chemical agents used to improve the plasticity of industrial polymers. Their ubiquitous use in multiple commercial products results in extensive exposure to humans and the environment. This study investigated cytotoxicity, endocrine disruption, effects mediated via AhR, lipid peroxidation and effects on expression of enzymes of xenobiotic metabolism caused by di-(2-ethy hexyl) phthalate (DEHP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and benzyl butyl phthalate (BBP) in developing fish embryos. Oxidative stress was identified as the critical mechanism of toxicity (CMTA) in the case of DEHP and DEP, while the efficient removal of DBP and BBP by phase 1 enzymes resulted in lesser toxicity. DEHP and DEP did not mimic estradiol (E(2)) in transactivation studies, but at concentrations of 10mg/L synthesis of sex steroid hormones was affected. Exposure to 10mg BBP/L resulted in weak transactivation of the estrogen receptor (ER). All phthalates exhibited weak potency as agonists of the aryl hydrocarbon receptor (AhR). The order of potency of the 4 phthalates studied was; DEHP>DEP>BBP>DBP. The study highlights the need for simultaneous assessment of (1) multiple cellular targets affected by phthalates and (2) phthalate mixtures to account for additive effects when multiple phthalates modulate the same pathway. Such cumulative assessment of multiple biological parameters is more realistic, and offers the possibility of more accurately identifying the CMTA.

Concepts: Phthalic acid, Dibutyl phthalate, Bis(2-ethylhexyl) phthalate, Estrogen, Steroid, Phthalate, Metabolism, Phthalates

28

Current treatments of organophosphorus nerve agents poisoning are imperfect, and more efficient medical countermeasures need to be developed. Chemical scavengers based on β-cyclodextrin displayed promising results, but further investigations have to be performed to evaluate the possibility of application of substituted cyclodextrins as potential detoxification agents. Herein, five new cyclodextrins scavengers were synthesized. New optimal conditions for regioselectively monosubstitution of β-cyclodextrin at O-2 position were then studied to access to key intermediates. After these optimizations, a new series of three permethylated derivatives was developed, and two compounds bearing an α-nucleophilic group via a three carbon atoms linker were prepared. The ability of these five scavengers to detoxify nerve agents (cyclosarin, soman, tabun and VX) was evaluated by a semi-quantitative biological assay. All the modified cyclodextrins significantly decreased the inhibitory effect of chemical warfare G agents on acetylcholinesterase activity. For this purpose, we showed that the specific interactions between the organophosphorus compound and the oligosaccharidic moiety of the scavenger played a pivotal role in the detoxification process.

Concepts: Chemical element, Cyclosarin, Tabun, Soman, Chemical warfare, Detoxification, Sarin, Nerve agent

28

This study was designed to investigate the modulatory effects of submicron and nanosized iron oxide (Fe(2)O(3)) particles on the ovalbumin (OVA)-induced immune Th2 response in BALB/c mice. Particles were intratracheally administered four times to mice before and during the OVA sensitization period. For each particle type, three different doses, namely 4×100, 4×250 or 4×500μg/mouse, were used and for each dose, four groups of mice, i.e. group saline solution (1), OVA (2), particles (3), and OVA plus particles (4), were constituted. Mice exposed to OVA alone exhibited an allergic Th2-dominated response with a consistent increase in inflammatory scores, eosinophil numbers, specific IgE levels and IL-4 production. When the mice were exposed to OVA and to high and intermediate doses of iron oxide submicron- or nanoparticles, the OVA-induced allergic response was significantly inhibited, as evidenced by the decrease in eosinophil cell influx and specific IgE levels. However, the low dose (4×100μg) of submicron particles had no significant effect on the OVA allergic response while the same dose of nanoparticles had an adjuvant effect on the Th2 response to OVA. In conclusion, these data demonstrate that the pulmonary immune response to OVA is a sensitive target for intratracheally instilled particles. Depending on the particle dose and size, the allergic response was suppressed or enhanced.

Concepts: Antibody, T helper cell, White blood cell, Immunology, Immunoglobulin E, Asthma, Allergy, Immune system

27

Exposure to lead (Pb) can induce kidney damage, which is related to induction of oxidative damage and disturbance of intracellular calcium homeostasis. Pb can readily permeate through dihydropyridine-sensitive L-type calcium channels and accumulate within cells. The objective of this study was to investigate protective effects of calcium channel blockers (CCBs) verapamil and nimodipine on nephrotoxicity induced by Pb acetate in mice. One hundred twenty male mice were randomly divided into 6 groups: control, Pb, low-dose verapamil, high-dose verapamil, low-dose nimodipine and high-dose nimodipine (n=20 per group). Pb acetate was injected intraperitoneally (i.p.) at 40mg/kg body weight/day for 10 days to establish the Pb toxicity model. While control mice received saline, mice of the treated groups simultaneously received i.p. injections of verapamil or nimodipine daily for 10 days. Both verapamil and nimodipine showed protection against Pb-induced kidney injury, including alleviation of renal pathological damage and decreasing the level of Pb in kidney homogenate and extent of apoptosis in nephrocytes. Moreover, verapamil and nimodipine significantly down-regulated levels of blood urea nitrogen and creatinine in the serum. In addition, verapamil and nimodipine administration decreased malondialdehyde content and increased activities of super oxide dismutase activity and glutathione peroxidase in the kidney homogenate. The findings in the present study implicate the therapeutic potential of CCBs for Pb-induced nephrotoxicity, which were at least partly due to the decrease of Pb uptake and inhibition of lipid peroxidation.

Concepts: Kidney, Nephrology, Calcium channel, Reactive oxygen species, Blood urea nitrogen, Oxidative stress, Antioxidant, Calcium channel blocker

26

The daily intakes (DI) were estimated in a Belgian general population for 5 phthalates, namely diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), di-iso-butyl phthalate (DiBP), butylbenzyl phthalate (BBzP) and di-2-ethylhexyl phthalate (DEHP), based on the urinary measurements of their corresponding metabolites. DI values ranged between

Concepts: Intake, Risk, Diethyl phthalate, Plasticizer, Bis(2-ethylhexyl) phthalate, Plasticizers, Phthalate, Phthalates

26

The increasing exposure to radiofrequency (RF) radiation emitted from mobile phone use has raised public concern regarding the biological effects of RF exposure on the male reproductive system. Autophagy contributes to maintaining intracellular homeostasis under environmental stress. To clarify whether RF exposure could induce autophagy in the spermatocyte, mouse spermatocyte-derived cells (GC-2) were exposed to 1800MHz Global System for Mobile Communication (GSM) signals in GSM-Talk mode at specific absorption rate (SAR) values of 1 w/kg, 2w/kg or 4w/kg for 24h, respectively. The results indicated that the expression of LC3-II increased in a dose- and time-dependent manner with RF exposure, and showed a significant change at the SAR value of 4w/kg. The autophagosome formation and the occurrence of autophagy were further confirmed by GFP-LC3 transient transfection assay and transmission electron microscopy (TEM) analysis. Furthermore, the conversion of LC3-I to LC3-II was enhanced by co-treatment with Chloroqrine (CQ), indicating autophagic flux could be enhanced by RF exposure. Intracellular ROS levels significantly increased in a dose- and time-dependent manner after cells were exposed to RF. Pretreatment with anti-oxidative NAC obviously decreased the conversion of LC3-I to LC3-II and attenuated the degradation of p62 induced by RF exposure. Meanwhile, phosphorylated extracellular-signal-regulated kinase (ERK) significantly increased after RF exposure at the SAR value of 2w/kg and 4w/kg. Moreover, we observed that RF exposure did not increase the percentage of apoptotic cells, but inhibition of autophagy could increase the percentage of apoptotic cells. These findings suggested that autophagy flux could be enhanced by 1800MHz GSM exposure (4w/kg), which is mediated by ROS generation. Autophagy may play an important role in preventing cells from apoptotic cell death under RF exposure stress.

Concepts: Electromagnetic radiation, Programmed cell death, Transfection, Electron, GSM, Specific absorption rate, Apoptosis, Mobile phone

26

Like most cell types, hepatocytes constantly produce extracellular vesicles (EVs) such as exosomes and microvesicles that are released into the circulation to transport signaling molecules and cellular waste. Circulating EVs are being vigorously explored as biomarkers of diseases and toxicities, including drug induced liver injury (DILI). Emerging data suggest that a) blood-borne EVs contain liver-specific mRNAs and microRNAs (miRNAs), b) the levels can be remarkably elevated in response to DILI, and c) the increases correlate well with classical measures of liver damage. The expression profile of mRNAs in EVs and the compartmentalization of miRNAs within EVs or other blood fractions were found to be indicative of the offending drug involved in DILI, thus providing more informative assessment of liver injury than using alanine aminotransferase (ALT) alone. EVs in the urine and cell culture medium were also found to contain proteins or mRNAs that were indicative of DILI. However, major improvements in EV isolation methods are needed for the discovery, evaluation and quantification of possible DILI biomarkers in circulating EVs.

Concepts: Evaluation, Bacteria, Messenger RNA, Gene, Alanine transaminase, Growth medium, Cell, Cell culture

26

Cosmetics are normally composed of various ingredients. Some cosmetic ingredients can act as chemical haptens reacting toward proteins or peptides of human skin and they can provoke an immunologic reaction, called as skin sensitization. This haptenation process is very important step of inducing skin sensitization and evaluating the sensitizing potentials of cosmetic ingredients is very important for consumer safety. Therefore, animal alternative methods focusing on monitoring haptenation potential are undergoing vigorous research. To examined the further usefulness of spectrophotometric methods to monitor reactivity of chemicals toward peptides for cosmetic ingredients. Forty chemicals (25 sensitizers and 15 non-sensitizers) were reacted with 2 synthetic peptides, e.g., the cysteine peptides (Ac-RFAACAA-COOH) with free thiol group and the lysine peptides (Ac-RFAAKAA-COOH) with free amine group. Unreacted peptides can be detected after incubating with 5,5'-dithiobis-2-nitrobenzoic acid or fluorescamine™ as detection reagents for free thiol and amine group, respectively. Chemicals were categorized as sensitizers when they induced more than 10% depletion of cysteine peptides or more than 30% depletion of lysine peptides. The sensitivity, specificity, and accuracy were 80.0%, 86.7% and 82.5%, respectively. These results demonstrate that spectrophotometric methods can be an easy, fast, and high-throughput screening tools predicting the skin sensitization potential of chemical including cosmetic ingredient.

Concepts: Skin, Cosmetics, Thiol, Disulfide bond, Amine, Nitrogen, Chemical reaction, Amino acid

12

Cannabidiol (CBD), a major non-psychotropic constituent of fiber-type cannabis plant, has been reported to possess diverse biological activities, including anti-proliferative effect on cancer cells. Although CBD is obtained from non-enzymatic decarboxylation of its parent molecule, cannabidiolic acid (CBDA), few studies have investigated whether CBDA itself is biologically active. Results of the current investigation revealed that CBDA inhibits migration of the highly invasive MDA-MB-231 human breast cancer cells, apparently through a mechanism involving inhibition of cAMP-dependent protein kinase A, coupled with an activation of the small GTPase, RhoA. It is established that activation of the RhoA signaling pathway leads to inhibition of the mobility of various cancer cells, including MDA-MB-231 cells. The data presented in this report suggest for the first time that as an active component in the cannabis plant, CBDA offers potential therapeutic modality in the abrogation of cancer cell migration, including aggressive breast cancers.

Concepts: Organism, Cancer support group, Cancer staging, Metastasis, Chemotherapy, Signal transduction, Cancer, Breast cancer