Synergistic effects of quercetin-loaded CoFe2O4@Liposomes regulate DNA damage and apoptosis in MCF-7 cancer cells: based on biophysical magnetic hyperthermia.

INTRODUCTION: Breast cancer (BC) is the most common malignancy in women globally. Significant progress has been made in developing structural nanoparticles (NPs) and formulations for targeted smart drug delivery (SDD) of pharmaceuticals, improving the precision of tumor cell targeting in therapy. SIGNIFICANCE: Magnetic hyperthermia (MHT) treatment using magneto-liposomes (MLs) has emerged as a promising adjuvant cancer therapy. METHODS: CoFe2O4 magnetic NPs (MNPs) were conjugated with nanoliposomes to form MLs, and the anticancer drug quercetin (Que) was loaded into MLs, forming Que-MLs composites for antitumor approach. The aim was to prepare Que-MLs for DD systems (DDS) under an alternating magnetic field (AMF), termed chemotherapy/hyperthermia (chemo-HT) techniques. The encapsulation efficiency (EE), drug loading capacity (DL), and drug release (DR) of Que and Que-MLs were evaluated. RESULTS: The results confirmed successful Que-loading on the surface of MLs, with an average diameter of 38 nm and efficient encapsulation into MLs (69%). In vitro, experimental results on MCF-7 breast cells using MHT showed high cytotoxic effects of novel Que-MLs on MCF-7 cells. Various analyses, including cytotoxicity, apoptosis, cell migration, western blotting, fluorescence imaging, and cell membrane internalization, were conducted. The Acridine Orange-ethidium bromide double fluorescence test identified 35% early and 55% late apoptosis resulting from Que-MLs under the chemo-HT group. TEM results indicated MCF-7 cell membrane internalization and digestion of Que-MLs, suggesting the presence of early endosome-like vesicles on the cytoplasmic periphery. CONCLUSIONS: Que-MLs exhibited multi-modal chemo-HT effects, displaying high toxicity against MCF-7 BC cells and showing promise as a potent cytotoxic agent for BC chemotherapy.

[Determination of cobalt in plasma blood samples by the ICP-MS method after oral intake of dietary supplements containing low doses of cobalt].

Salts of inorganic cobalt (Со) prevent the degradation of the alpha subunit of the hypoxia-inducible factor (HIF), imitating the state of hypoxia in the body and increasing the production of the endogenous hormone erythropoietin (EPO), and are used as doping substances that increase blood oxygen capacity and endurance, which give competitive advantages in sports. Currently, a large number of dietary supplements, including Co-containing ones, are offered on free sale. Their uncontrolled intake can affect not only the professional career of athletes, but also their health, due to the fact that this trace element and its salts are the strongest inorganic poisons and carcinogens. Despite this, their availability on the pharmaceutical market, a noticeable effect of erythropoiesis stimulation and a convenient oral form of administration lead to the need for their detection in modern doping control. The purpose of this research was to develop an approach to differentiate cobalt from vitamin B12, present in the body in its natural state, from the intake of cobalt salts by quantifying and comparing blood levels of vitamin B12 and total cobalt. Methods. The study involved 9 healthy volunteers (women and men) aged 25 to 45 years, leading an active lifestyle. Three of them took 2500 µg/day of cobalamin for 20 days (comparison group), three - dietary supplement containing cobalt asparaginate (100 µg/day in terms of pure cobalt), and the rest - dietary supplements with cobalt sulfate heptahydrate (100 µg/day in terms of pure cobalt) (administration groups) at the same time after meals. Blood samples were taken at baseline and on days 5, 9, 14 and 20. The concentrations of total cobalt in blood plasma samples of volunteers were measured by inductively coupled plasma mass-spectrometry (ICP-MS), the levels of cobalamin were determined on a Cobas 6000 immunochemical analyzer using the Elecsys Vitamin B12 II Assay ELISA kits. Results. It was found that oral intake of of cobalamin at a therapeutic dose significantly exceeding the recommended daily intake (3 µg), there was a regular slight increase in the blood concentration of total cobalt (1.1 times). At the same time intake of dietary supplements containing cobalt in the form of sulfate or asparaginate (about 100 µg per day in terms of pure cobalt) was accompanied by 4-6.7 fold increase in the concentration of total cobalt while unchanged vitamin B12 plasma concentration was observed. The detection of such changes can reliably indicate the use of prohibited salts and, of course, will be in demand for anti-doping control. Conclusion. Long-term monitoring of vitamin B12 and total cobalt levels, similar to hematological module of the Athlete Biological Passport program, will unambiguously detect possible abuse of cobalt salts and can be an additional evidence of the presence of these doping substances to other analytical methods, such as a combination of liquid chromatography and ICP-MS (LC-ICP-MS).

Cobalt chloride-stimulated hypoxia promotes the proliferation of cholesteatoma keratinocytes via the PI3K/Akt signaling pathway.

Herein, we purposed to explore whether hypoxia triggers proliferation of cholesteatoma keratinocytes via the PI3K-Akt signaling cascade. Cells were inoculated with different concentration of CoCl2. The proliferation and cellular HIF-1α, p-PDK1 and p­Akt expression levels of cholesteatoma keratinocytes were assessed in vitro. Hypoxia escalated cell proliferation via upregulating p-PDK1 and p­Akt expressions. Specific inhibitor of the PI3K-Akt signaling cascade, LY294002 markedly inhibited the expression of p­Akt and significantly reduces the hypoxia­induced proliferation of cholesteatoma keratinocytes. Our data provides research evidence confirming that hypoxia participates in the onset and progress of cholesteatoma.

Distinct Concentration-Dependent Molecular Pathways Regulate Bone Cell Responses to Cobalt and Chromium Exposure from Joint Replacement Prostheses.

Systemic cobalt (Co) and chromium (Cr) concentrations may be elevated in patients with metal joint replacement prostheses. Several studies have highlighted the detrimental effects of this exposure on bone cells in vitro, but the underlying mechanisms remain unclear. In this study, we use whole-genome microarrays to comprehensively assess gene expression in primary human osteoblasts, osteoclast precursors and mature resorbing osteoclasts following exposure to clinically relevant circulating versus local periprosthetic tissue concentrations of Co2+ and Cr3+ ions and CoCr nanoparticles. We also describe the gene expression response in osteoblasts on routinely used prosthesis surfaces in the presence of metal exposure. Our results suggest that systemic levels of metal exposure have no effect on osteoblasts, and primarily inhibit osteoclast differentiation and function via altering the focal adhesion and extracellular matrix interaction pathways. In contrast, periprosthetic levels of metal exposure inhibit both osteoblast and osteoclast activity by altering HIF-1α signaling and endocytic/cytoskeletal genes respectively, as well as increasing inflammatory signaling with mechanistic implications for adverse reactions to metal debris. Furthermore, we identify gene clusters and KEGG pathways for which the expression correlates with increasing Co2+:Cr3+ concentrations, and has the potential to serve as early markers of metal toxicity. Finally, our study provides a molecular basis for the improved clinical outcomes for hydroxyapatite-coated prostheses that elicit a pro-survival osteogenic gene signature compared to grit-blasted and plasma-sprayed titanium-coated surfaces in the presence of metal exposure.

Real-Time Monitoring the Effect of Cytopathic Hypoxia on Retinal Pigment Epithelial Barrier Functionality Using Electric Cell-Substrate Impedance Sensing (ECIS) Biosensor Technology.

Disruption of retinal pigment epithelial (RPE barrier integrity is a hallmark feature of various retinal blinding diseases, including diabetic macular edema and age-related macular degeneration, but the underlying causes and pathophysiology are not completely well-defined. One of the most conserved phenomena in biology is the progressive decline in mitochondrial function with aging leading to cytopathic hypoxia, where cells are unable to use oxygen for energy production. Therefore, this study aimed to thoroughly investigate the role of cytopathic hypoxia in compromising the barrier functionality of RPE cells. We used Electric Cell-Substrate Impedance Sensing (ECIS) system to monitor precisely in real time the barrier integrity of RPE cell line (ARPE-19) after treatment with various concentrations of cytopathic hypoxia-inducing agent, Cobalt(II) chloride (CoCl2). We further investigated how the resistance across ARPE-19 cells changes across three separate parameters: Rb (the electrical resistance between ARPE-19 cells), α (the resistance between the ARPE-19 and its substrate), and Cm (the capacitance of the ARPE-19 cell membrane). The viability of the ARPE-19 cells and mitochondrial bioenergetics were quantified with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and seahorse technology, respectively. ECIS measurement showed that CoCl2 reduced the total impedance of ARPE-19 cells in a dose dependent manner across all tested frequencies. Specifically, the ECIS program's modelling demonstrated that CoCl2 affected Rb as it begins to drastically decrease earlier than α or Cm, although ARPE-19 cells' viability was not compromised. Using seahorse technology, all three concentrations of CoCl2 significantly impaired basal, maximal, and ATP-linked respirations of ARPE-19 cells but did not affect proton leak and non-mitochondrial bioenergetic. Concordantly, the expression of a major paracellular tight junction protein (ZO-1) was reduced significantly with CoCl2-treatment in a dose-dependent manner. Our data demonstrate that the ARPE-19 cells have distinct dielectric properties in response to cytopathic hypoxia in which disruption of barrier integrity between ARPE-19 cells precedes any changes in cells' viability, cell-substrate contacts, and cell membrane permeability. Such differences can be used in screening of selective agents that improve the assembly of RPE tight junction without compromising other RPE barrier parameters.

Selenomethionine protects hematopoietic stem/progenitor cells against cobalt nanoparticles by stimulating antioxidant actions and DNA repair functions.

Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) can differentiate into all blood lineages to maintain hematopoiesis, wound healing, and immune functions. Recently, cobalt-chromium alloy casting implants have been used extensively in total hip replacements; however, cobalt nanoparticles (CoNPs) released from the alloy were toxic to HSCs and HPCs. We aimed to investigate the mechanism underlying the toxic effect of CoNPs on HSCs/HPCs and to determine the protective effect of selenomethionine (SeMet) against CoNPs in vitro and in vivo. Human and rat CD34+ HSCs/HPCs were isolated from cord blood and bone marrow, respectively. CoNPs decreased the viability of CD34+ HSCs/HPCs and increased apoptosis. SeMet attenuated the toxicity of CoNPs by enhancing the antioxidant ability of cells. The protective effect of SeMet was not completely abolished after adding H2O2 to abrogate the improvement of the antioxidant capacity by SeMet. SeMet and CoNPs stimulated ATM/ATR DNA damage response signals and inhibited cell proliferation. Unlike CoNPs, SeMet did not damage the DNA, and cell proliferation recovered after removing SeMet. SeMet inhibited the CoNP-induced upregulation of hypoxia inducible factor (HIF)-1α, thereby disrupting the inhibitory effect of HIF-1α on breast cancer type 1 susceptibility protein (BRCA1). Moreover, SeMet promoted BRCA1-mediated ubiquitination of cyclin B by upregulating UBE2K. Thus, SeMet enhanced cell cycle arrest and DNA repair post-CoNP exposure. Overall, SeMet protected CD34+ HSCs/HPCs against CoNPs by stimulating antioxidant activity and DNA repair.

Cobalt chloride-simulated hypoxia elongates primary cilia in immortalized human retina pigment epithelial-1 cells.

Primary cilia are microtubule-based organelles that are involved in sensing micro-environmental cues and regulating cellular homeostasis via triggering signaling cascades. Hypoxia is one of the most common environmental stresses that organ and tissue cells may often encounter during embryogenesis, cell differentiation, infection, inflammation, injury, cerebral and cardiac ischemia, or tumorigenesis. Although hypoxia has been reported to promote or inhibit primary ciliogenesis in different tissues or cultured cell lines, the role of hypoxia in ciliogenesis is controversial and still unclear. Here we investigated the primary cilia change under cobalt chloride (CoCl2)-simulated hypoxia in immortalized human retina pigment epithelial-1 (hTERT RPE-1) cells. We found CoCl2 treatment elongated primary cilia in a time- and dose-dependent manner. The prolonged cilia recovered back to near normal length when CoCl2 was washed out from the cell culture medium. Under CoCl2-simulated hypoxia, the protein expression levels of HIF-1/2α and acetylated-α-tubulin (cilia marker) were increased, while the protein expression level of Rabaptin-5 is decreased during hypoxia. Taken together, our results suggest that hypoxia may elongate primary cilia by downregulating Rabaptin-5 involved endocytosis. The coordination between endocytosis and ciliogenesis may be utilized by cells to adapt to hypoxia.

Carcinogenic hazard assessment of cobalt-containing alloys in medical devices: Review of in vivo studies.

Cobalt (Co) alloys have been used for over seven decades in a wide range of medical devices, including, but not limited to, hip and knee implants, surgical tools, and vascular stents, due to their favorable biocompatibility, durability, and mechanical properties. A recent regulatory hazard classification review by the European Chemicals Agency (ECHA) resulted in the classification of metallic Co as a Class 1B Carcinogen (presumed to have carcinogenic potential for humans), primarily based on inhalation rodent carcinogenicity studies with pure metallic Co. The ECHA review did not specifically consider the carcinogenicity hazard potential of forms or routes of Co that are relevant for medical devices. The purpose of this review is to present a comprehensive assessment of the available in vivo preclinical data on the carcinogenic hazard potential of exposure to Co-containing alloys (CoCA) in medical devices by relevant routes. In vivo data were reviewed from 33 preclinical studies that examined the impact of Co exposure on local and systemic tumor incidence in rats, mice, guinea pigs, and hamsters. Across these studies, there was no significant increase of local or systemic tumors in studies relevant for medical devices. Taken together, the relevant in vivo data led to the conclusion that CoCA in medical devices are not a carcinogenic hazard in available in vivo models. While specific patient and implant factors cannot be fully replicated using in vivo models, the available in vivo preclinical data support that CoCA in medical devices are unlikely a carcinogenic hazard to patients.

Suitable test concentration of cobalt and concomitant reactivity to nickel and chromium: A multicentre study from the Swedish Contact Dermatitis Research Group.

BACKGROUND: In Sweden, cobalt chloride 0.5% has been included in the baseline series since the mid-1980s. A recent study from Stockholm showed that cobalt chloride 1% petrolatum (pet.) was more suitable than 0.5%. Cobalt chloride at 1.0% has been patch tested for decades in many European countries and around the world. OBJECTIVES: To study the suitability of patch testing to cobalt 1.0% vs 0.5% and to analyze the co-occurrence of allergy to cobalt, chromium, and nickel. RESULTS: Contact allergy to cobalt was shown in 90 patients (6.6%). Eighty (5.9%) patients tested positive to cobalt 1.0%. Thirty-seven of the 90 patients (41.1%) with cobalt allergy were missed by cobalt 0.5% and 10 (0.7%) were missed by cobalt 1.0% (P < .001). No case of patch test sensitization was reported. Allergy to chromium was seen in 2.6% and allergy to nickel in 13.3%. Solitary allergy to cobalt without nickel allergy was shown in 61.1% of cobalt-positive individuals. Female patients had larger proportions of positive reactions to cobalt (P = .036) and nickel (P < .001) than males. CONCLUSION: The results speak in favor of replacing cobalt chloride 0.5% with cobalt chloride 1.0% pet. in the Swedish baseline series, which will be done 2021.

Involvement of the ventral, but not dorsal, hippocampus in anxiety-like behaviors in mice exposed to the elevated plus maze: participation of CRF1 receptor and PKA pathway.

BACKGROUND: The hippocampus is a limbic structure involved in anxiety-like behaviors. We aimed to evaluate the role of the dorsal (DH) and ventral (VH) hippocampus in anxiety-like behaviors in the elevated plus maze (EPM). METHODS: We inhibited these brain regions using cobalt chloride (CoCl2: 1.0 nmol) microinjections. We also investigated the involvement of corticotropin-releasing factor (CRF) action and protein kinase A (PKA) pathway using intra-DH and intra-VH microinjections of the CRF1 receptor antagonist CP376395 (0, 3.0, or 6.0 nmol) and the PKA inhibitor H-89 (0, 2.5, or 5.0 nmol). RESULTS: The results indicated that intra-VH CoCl2 microinjection increased the percentage of time spent and entries in the open arms. The mice also exhibited fewer stretch attend postures in the protected area and increased percentage of open arm entries. Further, intra-VH injection of 3.0 nmol CP376395 increased time spent in the open arms. Intra-DH injection of 6.0 nmol CP376395 increased the frequency of unprotected head dipping, whereas intra-VH injection of 6 nmol CP376395 increased the frequency of protected head dipping. Intra-VH, but not intra-DH, microinjection of 2.5 nmol H-89 increased the percentages of open arm entries and time spent in the open arms. Microinjection of 2.5 and 5.0 nmol H-89 reduced the frequency of protected head dipping behavior. CONCLUSIONS: This study demonstrated that VH modulates anxiety-like behaviors in EPM. Moreover, CRF and the cAMP/PKA pathway seem to modulate these effects.

Feeding a calf starter containing monensin alone or in combination with an oregano, and cobalt blend to Holstein calves.

Gut health is critically important for growing neonatal calves, and nutritional technologies are needed to prevent disease and stress challenges. Previous work feeding monensin (MON) in combination with an oregano, prebiotic, and cobalt-lactate (EOC) blend had demonstrated improved calf gut health and growth performance. The objective of this study was to evaluate the growth performance of calves fed MON and EOC alone or in combination. Eighty (80) newborn Holstein (37) female and (43) male calves were randomly assigned to one of four treatments arranged in a 2 × 2 factorial (MON and EOC). Treatments were: 1) Control: without MON or EOC added to the calf starter (CS); 2) MON: 50.8 mg/kg CS (Elanco, Greenfield, IN); 3) EOC: 44.1 mg/kg CS (Rum-A-Fresh, Ralco Inc. Marshall, MN); 4) MON + EOC: MON and EOC added to CS. Calves were fed colostrum followed by whole milk through weaning at 42 d, while CS was fed ad libitum through the 70-d experimental period. The MON by EOC interaction was found to be nonsignificant (P > 0.41) for growth performance. Calves fed without or with MON demonstrated similar (P > 0.70) body weight (BW; 68.7 and 68.9 kg without and with MON, respectively), while calves fed EOC demonstrated greater (P < 0.01) BW (67.3 and 70.4 kg without and with EOC, respectively) compared with calves fed without EOC. Calves fed a CS containing MON were similar (P > 0.47) in average daily gain (ADG; 0.88 and 0.91 kg/d) compared with calves fed without MON; however, feeding calves a CS with EOC increased (P < 0.01) ADG (0.84 and 0.95 kg/d) by 13% through the 70-d experimental period compared with calves not fed EOC. Frame measurements indicated that the greater ADG was due to increased (P < 0.10) frame growth for calves fed essential oils (EO) compared with calves fed without EO. A MON by EOC interaction (P < 0.01) for serum propionate concentration demonstrated calves fed MON + EOC and EOC were greater (P < 0.05) compared with calves fed Control, while calves fed MON were intermediate and different (P < 0.05). Feeding calves a CS with EOC increased (P < 0.04) immunoglobulin A, immunoglobulin G, and immunoglobulin M concentrations compared with calves fed without EOC. A MON by EOC interaction was detected (P < 0.01) for total tract starch digestibility for calves fed EOC or MON + EOC demonstrating greater (P < 0.05) starch digestibilities than Control-fed calves. These data demonstrate that EOC and MON fed in combination was not beneficial for enhancing the growth performance, but that calf growth performance can be improved with EOC compared with MON.

Ethanolic Extract of Moringa oleifera Leaves Influences NF-κB Signaling Pathway to Restore Kidney Tissue from Cobalt-Mediated Oxidative Injury and Inflammation in Rats.

This study aimed to describe the protective efficacy of Moringa oleifera ethanolic extract (MOEE) against the impact of cobalt chloride (CoCl2) exposure on the rat's kidney. Fifty male rats were assigned to five equal groups: a control group, a MOEE-administered group (400 mg/kg body weight (bw), daily via gastric tube), a CoCl2-intoxicated group (300 mg/L, daily in drinking water), a protective group, and a therapeutic co-administered group that received MOEE prior to or following and concurrently with CoCl2, respectively. The antioxidant status indices (superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH)), oxidative stress markers (hydrogen peroxide (H2O2), 8-hydroxy-2-deoxyguanosine (8-OHdG), and malondialdehyde (MDA)), and inflammatory response markers (nitric oxide (NO), tumor necrosis factor (TNF-α), myeloperoxidase (MPO), and C-reactive protein (CRP)) were evaluated. The expression profiles of pro-inflammatory cytokines (nuclear factor-kappa B (NF-kB) and interleukin-6 (IL-6)) were also measured by real-time quantitative polymerase chain reaction (qRT-PCR). The results showed that CoCl2 exposure was associated with significant elevations of oxidative stress and inflammatory indices with reductions in the endogenous tissue antioxidants' concentrations. Moreover, CoCl2 enhanced the activity of the NF-κB inflammatory-signaling pathway that plays a role in the associated inflammation of the kidney. MOEE ameliorated CoCl2-induced renal oxidative damage and inflammatory injury with the suppression of the mRNA expression pattern of pro-inflammatory cytokine-encoding genes. MOEE is more effective when it is administered with CoCl2 exposure as a prophylactic regimen. In conclusion, MOEE administration exhibited protective effects in counteracting CoCl2-induced renal injury in rats.

Immobilization of novel inorganic nano-complexes onto MWCNT nanomaterials as a novel adsorbent and anti-inflammatory therapy in an induced model of rheumatoid arthritis.

Novel supported inorganic metal nano-complexes of Ag(I) and Co(II) derived from 4-amino-N-(4-methylpyrimidin-2-yl) benzene sulfonamide (SulMer) were synthesized using olive leaf extract as a reducing agent with grinding and microwave methods. The prepared samples were denoted as Comp1-6. The surface morphologies of the synthesized nanomaterials were analyzed using C, H, N, S analysis, Fourier-transform infrared spectroscopy, UV- visible spectroscopy, proton and carbon nuclear magnetic resonance, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and x-ray powder diffraction (XRD) analysis. The data revealed that all the synthesized complexes exhibited a 1:1 metal-to-ligand ratio with a coordination number of 4 or 6. The mean particle size of the nanomaterial samples was 25-35 nm. The XRD patterns indicated a crystalline nature for the complexes. The supported inorganic metal nano-complexes displayed good activity in the adsorptive removal of Direct Red 81 (DR-81) from aqueous solutions. In addition, the effect of the supported metal nano-complexes on the immune system was studied as well as how these anti-inflammatory compounds could be used to treat many autoimmune diseases, most notably rheumatoid arthritis. An experimental model for arthritis can be induced using complete Freund's adjuvant. It was shown that the supported complex offers several advantages such stability, eco-friendliness, simple experimental conditions, short reaction times, and easy work- up.

Dual response mimetic enzyme of novel Co4S3/Co3O4 composite nanotube for antibacterial application.

Novel Co4S3/Co3O4 composite nanotubes were first time successfully synthesized through the control of Na2S treatment of Co(CO3)0.35Cl0.20(OH)1.10 precursor and testified to having both oxidase-like and peroxidase-like catalytic activities. Through nanoscale Kirkendall effect, acicular precursor was vulcanized to form Co4S3/Co3O4 nanotubes (NTs). Co4S3/Co3O4 NTs exhibit great properties such as smaller Km and higher Vmax than natural horseradish peroxidase, favorable selectivity and ideal stability. Co4S3/Co3O4 NTs with promising biocompatibility can realize spectral sterilization towards Escherichia coli and Staphylococcus sciuri in the presence of low level H2O2. It turned to be that superoxide anion radical catalyzed by Co4S3/Co3O4 NTs not only oxidizes 3, 3', 5, 5'-tetramethylbenzidine in the catalytic process but also eliminates gram-bacteria during sterilization. The successful synthesis of biofunctional Co4S3/Co3O4 NTs can serve as significant applications of new energy and environmental catalysis.

Bioelution, Bioavailability, and Toxicity of Cobalt Compounds Correlate.

Based on the wide use of cobalt substances in a range of important technologies, it has become important to predict the toxicological properties of new or lesser-studied substances as accurately as possible. We studied a group of 6 cobalt substances with inorganic ligands, which were tested for their bioaccessibility (surrogate measure of bioavailability) through in vitro bioelution in simulated gastric and intestinal fluids. Representatives of the group also underwent in vivo blood kinetics and mass balance tests, and both oral acute and repeated dose toxicity (RDT) testing. We were able to show a good correlation between high in vitro bioaccessibility with high in vivo bioavailability and subsequent high in vivo toxicity; consequently, low in vitro bioaccessibility correlated well with low in vivo bioavailability and low in vivo toxicity. In vitro bioelution in simulated gastric fluid was the most precise predictor of the difference in the oral RDT lowest observed adverse effect levels of 2 compounds representing the highly and poorly bioaccessible subset of substances. The 2 compounds cobalt dichloride hexahydrate and tricobalt tetraoxide differed by a factor of 440 in their in vitro bioaccessibility and by a factor of 310 in their RDT lowest observed adverse effect level. In summary, this set of studies shows that solubility, specifically in vitro bioelution in simulated gastric fluid, is a good, yet conservative, predictor of in vivo bioavailability and oral systemic toxicity of inorganic cobalt substances. Bioelution data are therefore an invaluable tool for grouping and read across of cobalt substances for hazard and risk assessment.

Cobalt-induced retrotransposon polymorphism and humic acid protection on maize genome.

Retrotransposon activity and genomic template stability (GTS) are one of the most significant rearranging mechanisms in environmental stress. Therefore, in this study, it is aimed to elucidate effecting of Cobalt (Co) on the instability of genomes and Long Terminal Repeat retrotransposon polymorphism in Zea mays and whether humic acid (HA) has any role on these parameters. For this purpose, Retrotransposon-microsatellite amplified polymorphism (REMAP) and Inter-Retrotransposon Amplified Polymorphism (IRAP) markers were applied to evaluate retrotransposon polymorphism and the GTS levels. It was found that IRAP and REMAP primers generate unique polymorphic band structures on maize plants treated with various doses of Co. Retrotransposon polymorphism increased and GTS decreased while increasing Co concentration. On the other hand, there was a reduction in negative effects of Co on retrotransposon GTS and polymorphism after treatment with HA. The results indicate that HA may be used effectively for the protection of maize seedlings from the destructive effects of Co toxicity.

Ameliorative effects of melatonin against nano and ionic cobalt induced genotoxicity in two in vivo Drosophila assays.

The aim of this study is to evaluate the ameliorative effect of melatonin (MEL) against induced genotoxicity by cobalt (II) chloride (CoCl2) and cobalt nanoparticles (CoNPs) (50 nm). Genotoxicity of CoCl2 and CoNPs were investigated using single cell gel electrophoresis (COMET) in Drosophila melanogaster hemocytes, which are blood cells of the Drosophila, and the somatic mutation and recombination test (SMART) was used to investigate mutant effects on the Drosophila wings. Three concentrations (0.1, 1, and 10 mM) of CoNPs and CoCl2 were applied to demonstrate their genotoxic potential. Both CoNPs and CoCl2 have mutagenic potential for the three concentrations tested in the COMET assay; however, only the 10 mM concentration of the ionic form and two high concentrations (1 and 10 mM) of CoNPs induced genotoxicity in the Drosophila SMART assay. Three different concentrations of MEL (0.1, 0.5 and 2.5 mM) were used against cobalt at highest concentration (10 mM) of both CoCl2 and CoNPs in both the SMART and COMET assays. MEL ameliorated the genotoxicity induced by CoCl2 and CoNPs in vivo Drosophila COMET and SMART assays.

Development and Assessment of Nano-Technologies for Cancer Treatment: Cytotoxicity and Hyperthermia Laboratory Studies.

Cancer treatment by magnetic hyperthermia offers numerous advantages, but for practical applications many variables still need to be adjusted before developing a controlled and reproducible cancer treatment that is bio-compatible (non-damaging) to healthy cells. In this work, Fe3O4 and CoFe2O4 were synthesized and systematically studied for the development of efficient therapeutic agents for applications in hyperthermia. The biocompatibility of the materials was further evaluated using HepG2 cells as biological model. Colorimetric and microscopic techniques were used to evaluate the interaction of magnetic nano-materials (MNMs) and HepG2 cells. Finally, the behavior of MNMs was evaluated under the influence of an alternating magnetic field (AMF), observing a more efficient temperature increment for CoFe2O4, a desirable behavior for biomedical applications since lower doses and shorter expositions to alternating magnetic field might be required.

Endogenous synthesis of milk cis-9,trans-11 conjugated linoleic acid in dairy ewes: Quantification using 13C-labeled vaccenic acid and comparison with estimates based on cobalt administration.

Isotopic tracers are used to directly quantify the effect of mammary Δ9-desaturation on milk fatty acid (FA) composition, but very few studies have applied this method to measuring the endogenous synthesis of rumenic acid (RA; cis-9,trans-11 conjugated linoleic acid) in cows and goats, and no publications exist in ewes. In sheep, knowledge about the contribution of stearoyl-coenzyme A desaturase (SCD) to milk FA secretion is derived mostly from indirect estimates based on inhibition of the enzyme by oral administration of cobalt, a cost-effective method that has not been validated to date. To fill both gaps, we conducted an isotopic tracer assay in sheep to quantify the proportion of endogenous RA in milk for the first time in this species. We then compared the results with estimates derived from a Co administration assay performed on the same animals. First, 5 lactating ewes received an intravenous injection of 200 mg of [1-13C]trans-11 18:1 (vaccenic acid, VA), the precursor for RA production by SCD activity. At -24, -15, 0, 9, 24, 33, 48, 57, 72, 81, and 96 h post-injection, we recorded milk yield and collected milk samples to examine fat concentration and FA profile. We conducted compound-specific isotope analysis of VA and RA by gas chromatography-combustion isotope ratio mass spectrometry. Afterward, in the Co administration assay, ewes received a daily dose of 7 mg of Co/kg of body weight for 5 d. We analyzed milk samples for composition before and on the last days of cobalt dosing. On average, 17% of the injected amount of [1-13C]VA was transferred to milk within 96 h post-injection, and up to 29% of the VA taken up by the mammary gland was desaturated to milk RA. Under our conditions, the mean proportion of this conjugated linoleic acid isomer deriving from Δ9-desaturation represented 82 to 90% of the amount secreted in milk. However, the proportion estimated in the Co assay with calculations based on individual FA concentrations was lower (on average, 46%). When we calculated the same estimates based on changes in Δ9-desaturation ratios after Co dosing, the higher values of endogenous RA (75%) did not differ from the results of the isotopic tracer assay. Nevertheless, correlation analysis between the results obtained through [1-13C]VA or Co administration revealed no significant relationship, which would prevent acceptance of the latter as a reliable alternative to isotopic labeling to examine mammary Δ9-desaturation in dairy ewes.

A Cobalt Schiff-Base Complex as a Putative Therapeutic for Azide Poisoning.

There is presently no antidote available to treat azide poisoning. Here, the Schiff-base compound Co(II)-2,12-dimethyl-3,7,11,17-tetraazabicyclo-[11.3.1]heptadeca-1(17)2,11,13,15-pentaenyl dibromide (Co(II)N4[11.3.1]) is investigated to determine if it has the capability to antagonize azide toxicity through a decorporation mechanism. The stopped-flow kinetics of azide binding to Co(II)N4[11.3.1] in the absence of oxygen exhibited three experimentally observable phases: I (fast); II (intermediate); and III (slow). The intermediate phase II accounted for ∼70% of the overall absorbance changes, representing the major process observed, with second-order rate constants of 29 (±4) M-1 s-1 at 25 °C and 70 (±10) M-1 s-1 at 37 °C. The data demonstrated pH independence of the reaction around neutrality, suggesting the unprotonated azide anion to be the attacking species. The binding of azide to Co(II)N4[11.3.1] appears to have a complicated mechanism leading to less than ideal antidotal capability; nonetheless, this cobalt complex does protect against azide intoxication. Administration of Co(II)N4[11.3.1] at 5 min post sodium azide injection (ip) to mice resulted in a substantial decrease of righting-recovery times, 12 (±4) min, compared to controls, 40 (±8) min. In addition, only two out of seven mice "knocked down" when the antidote was administered compared to the controls given toxicant only (100% knockdown).