PeerJ Preprints: Toxicologyhttps://peerj.com/preprints/index.atom?journal=peerj&subject=2800Toxicology articles published in PeerJ PreprintsAflatoxins in Uganda: an encyclopedic review of the etiology, epidemiology, detection, quantification, exposure assessment, reduction and controlhttps://peerj.com/preprints/279632019-09-162019-09-16Timothy OmaraWinfred NassaziTom OmuteAburu AwathFortunate LakerRaymond KalukusuBashir MusauBrenda V NakabuyeSarah KagoyaGeorge OtimEddie Adupa
Uganda is predominantly an agricultural country where farming employ more than 60% of the population. Aflatoxins remain a scourge in the country, unprecedentedly reducing the value of agricultural foods and in high enough exposure levels, implicated for hepatocellular carcinoma, stunted growth in children and untimely deaths. This review synthetizes the country’s major findings in relation to the mycotoxin’s etiology, epidemiology, detection, quantification, exposure assessment, control and reduction in different matrices. It also highlights some of the management strategies for aflatoxin control that could be adopted in Uganda. Review results indicate that aflatoxins in Uganda is majorly produced by Aspergillus flavus and A. parasiticus and have been reported in maize (Zea mays L.), sorghum (Sorghum bicolor L.), sesame (Sesamum indicum), beans (Phaseolus vulgaris L.), sunflower (Helianthus annus), millet (Eleusine coracana), a bovine milk-based product, peanuts (Arachis hypogaea L.) and cassava (Manihot esculenta) with the highest content reported in cassava, beans and peanuts. The causes and proliferation of aflatoxigenic contamination of Ugandan foods have been largely due to poor pre-, peri- and post-harvest activities, poor government legislation, lack of awareness and low levels of education among farmers, agri-entreprenuers and consumers on the plague. Aflatoxin B1 is the most prevalent aflatoxin in Uganda. There is still limited research on aflatoxins in Uganda because the surveillance, reduction and control carry prohibitive costs. A few exposure assessments have been done especially in human sera and dependence on a single or a related set of foods with little diet diversity has exacerbated the risk of exposure to aflatoxins in Uganda because most of the staple foods are aflatoxin-prone. On the detection, control and reduction, these are still marginal, though some devoted scholars have devised and validated a sensitive portable device for on-site aflatoxin detection in maize as well as shown that starter cultures used for making some cereal-based beverages have the potential to bind aflatoxins. More effort should be geared towards awareness creation through training of farmers and traders in the cereal value chain as well as developing capacity to monitor aflatoxins. Vaccination against Hepatitis B and Hepatitis A should be emphasized to reduce the risk of development of liver cancer among the populace.
Uganda is predominantly an agricultural country where farming employ more than 60% of the population. Aflatoxins remain a scourge in the country, unprecedentedly reducing the value of agricultural foods and in high enough exposure levels, implicated for hepatocellular carcinoma, stunted growth in children and untimely deaths. This review synthetizes the country’s major findings in relation to the mycotoxin’s etiology, epidemiology, detection, quantification, exposure assessment, control and reduction in different matrices. It also highlights some of the management strategies for aflatoxin control that could be adopted in Uganda. Review results indicate that aflatoxins in Uganda is majorly produced by Aspergillus flavus and A. parasiticus and have been reported in maize (Zea mays L.), sorghum (Sorghum bicolor L.), sesame (Sesamum indicum), beans (Phaseolus vulgaris L.), sunflower (Helianthus annus), millet (Eleusine coracana), a bovine milk-based product, peanuts (Arachis hypogaea L.) and cassava (Manihotesculenta) with the highest content reported in cassava, beans and peanuts. The causes and proliferation of aflatoxigenic contamination of Ugandan foods have been largely due to poor pre-, peri- and post-harvest activities, poor government legislation, lack of awareness and low levels of education among farmers, agri-entreprenuers and consumers on the plague. Aflatoxin B1 is the most prevalent aflatoxin in Uganda. There is still limited research on aflatoxins in Uganda because the surveillance, reduction and control carry prohibitive costs. A few exposure assessments have been done especially in human sera and dependence on a single or a related set of foods with little diet diversity has exacerbated the risk of exposure to aflatoxins in Uganda because most of the staple foods are aflatoxin-prone. On the detection, control and reduction, these are still marginal, though some devoted scholars have devised and validated a sensitive portable device for on-site aflatoxin detection in maize as well as shown that starter cultures used for making some cereal-based beverages have the potential to bind aflatoxins. More effort should be geared towards awareness creation through training of farmers and traders in the cereal value chain as well as developing capacity to monitor aflatoxins. Vaccination against Hepatitis B and Hepatitis A should be emphasized to reduce the risk of development of liver cancer among the populace.Aflatoxigenic contamination of freshly harvested white maize (Zea mays L.) from some selected Ugandan districtshttps://peerj.com/preprints/278882019-08-082019-08-08Timothy Omara
The moisture content and total aflatoxin (AF) content of 27 samples of freshly harvested white maize (Zea mays L.) from Mubende (n = 3), Ibanda (n = 3), Jinja (n = 3), Mayuge (n = 3) , Buikwe (n = 3), Hoima (n = 3), Mpigi (n = 3), Masindi (n = 3) and Bugiri (n = 3) districts of Uganda representing the agroecological zones: Lake Victoria crescent, Western Highlands, South East and Lake Albert Crescent were determined in the second season harvest of January 2019 to March 2019. Moisture content ranged from 12.9 to 18.8% (mean moisture content varied from 13.9±0.35-17.2±1.55%) with the highest moisture recorded in maize from Ibanda. The highest mean AF contamination of 11.0±3.01 μg/kg was recorded in maize from Hoima while the lowest AF content of 3.8±1.30 μg/kg was recorded in maize from Mpigi. Despite the fact that all the samples had detectable aflatoxins, none of the maize samples had aflatoxin greater than WHO regulatory limit of 20 μg/kg. White maize in Uganda are precontaminated by aflatoxins prior to harvest. Whereas the spectre of aflatoxigenic contamination of foods remains a ticklish challenge to address, strategic adaptation and deployment of appropriate interventions can help secure a safe harvest. Farmers should plant maize varieties with established maturity periods to ensure timely harvesting. Further research should assess the presence of other mycotoxins as zearalenone, sterigmatocystin, ochratoxin A, citrinin, vomitoxin and diacetoxyscirpenol that may co-occur with aflatoxins in freshly harvested maize.
The moisture content and total aflatoxin (AF) content of 27 samples of freshly harvested white maize (Zea mays L.) from Mubende (n = 3), Ibanda (n = 3), Jinja (n = 3), Mayuge (n = 3) , Buikwe (n = 3), Hoima (n = 3), Mpigi (n = 3), Masindi (n = 3) and Bugiri (n = 3) districts of Uganda representing the agroecological zones: Lake Victoria crescent, Western Highlands, South East and Lake Albert Crescent were determined in the second season harvest of January 2019 to March 2019. Moisture content ranged from 12.9 to 18.8% (mean moisture content varied from 13.9±0.35-17.2±1.55%) with the highest moisture recorded in maize from Ibanda. The highest mean AF contamination of 11.0±3.01 μg/kgwas recorded in maize from Hoima while the lowest AF content of 3.8±1.30 μg/kg was recorded in maize from Mpigi. Despite the fact that all the samples had detectable aflatoxins, none of the maize samples had aflatoxin greater than WHO regulatory limit of 20 μg/kg. White maize in Uganda are precontaminated by aflatoxins prior to harvest. Whereas the spectre of aflatoxigenic contamination of foods remains a ticklish challenge to address, strategic adaptation and deployment of appropriate interventions can help secure a safe harvest. Farmers should plant maize varieties with established maturity periods to ensure timely harvesting. Further research should assess the presence of other mycotoxins as zearalenone, sterigmatocystin, ochratoxin A, citrinin, vomitoxin and diacetoxyscirpenol that may co-occur with aflatoxins in freshly harvested maize.T1000: A reduced toxicogenomics gene set for improved decision makinghttps://peerj.com/preprints/278392019-07-032019-07-03Othman SoufanJessica EwaldCharles ViauDoug CrumpMarkus HeckerNiladri BasuJianguo Xia
There is growing interest within regulatory agencies and toxicological research communities to develop, test, and apply new approaches, such as toxicogenomics, to more efficiently evaluate chemical hazards. Given the complexity of analyzing thousands of genes simultaneously, there is a need to identify reduced gene sets.Though several gene sets have been defined for toxicological applications, few of these were purposefully derived using toxicogenomics data. Here, we developed and applied a systematic approach to identify 1000 genes (called Toxicogenomics-1000 or T1000) highly responsive to chemical exposures. First, a co-expression network of 11,210genes was built by leveraging microarray data from the Open TG-GATEs program. This network was then re-weighted based on prior knowledge of their biological (KEGG, MSigDB) and toxicological (CTD) relevance. Finally, weighted correlation network analysis was applied to identify 258 gene clusters. T1000 was defined by selecting genes from each cluster that were most associated with outcome measures. For model evaluation, we compared the performance of T1000 to that of other gene sets (L1000, S1500, Genes selected by Limma, and random set) using two external datasets. Additionally, a smaller (T384) and a larger version (T1500) of T1000 were used for dose-response modeling to test the effect of gene set size. Our findings demonstrated that the T1000 gene set is predictive of apical outcomes across a range of conditions (e.g.,in vitroand in vivo, dose-response, multiple species, tissues, and chemicals), and generally performs as well, or better than other gene sets available.
There is growing interest within regulatory agencies and toxicological research communities to develop, test, and apply new approaches, such as toxicogenomics, to more efficiently evaluate chemical hazards. Given the complexity of analyzing thousands of genes simultaneously, there is a need to identify reduced gene sets.Though several gene sets have been defined for toxicological applications, few of these were purposefully derived using toxicogenomics data. Here, we developed and applied a systematic approach to identify 1000 genes (called Toxicogenomics-1000 or T1000) highly responsive to chemical exposures. First, a co-expression network of 11,210genes was built by leveraging microarray data from the Open TG-GATEs program. This network was then re-weighted based on prior knowledge of their biological (KEGG, MSigDB) and toxicological (CTD) relevance. Finally, weighted correlation network analysis was applied to identify 258 gene clusters. T1000 was defined by selecting genes from each cluster that were most associated with outcome measures. For model evaluation, we compared the performance of T1000 to that of other gene sets (L1000, S1500, Genes selected by Limma, and random set) using two external datasets. Additionally, a smaller (T384) and a larger version (T1500) of T1000 were used for dose-response modeling to test the effect of gene set size. Our findings demonstrated that the T1000 gene set is predictive of apical outcomes across a range of conditions (e.g.,in vitroand in vivo, dose-response, multiple species, tissues, and chemicals), and generally performs as well, or better than other gene sets available.L-methionine sulfoximine interacted with propofol and showed toxicity in PC12 cellshttps://peerj.com/preprints/278032019-06-162019-06-16Ruicong GuanJing ChenFei XiaoYubo Xie
Background: L-Methionine sulfoximine (MSO) inhibits glutamine synthesis in a rodent animal model, and its limited clinical use is implicitly associated with glutamate deprivation and neurotoxicity. The purpose of this experiment was to determine the effect of MSO on pheochromocytoma (PC12) cells and its interaction with propofol-induced neuro-apoptosis. Objective: To study the effects of MSO on cell viability following 100 μM propofol treatment and the impact of ribosomal S6 kinase 1 (RSK1) signaling on the PC12 cell line. Methods: PC12 cells were exposed to propofol-triggered neurotoxicity for 6 h and then subjected to MSO treatment. The gene and protein expression levels of members of the RSK1 signaling pathway were determined by real-time polymerase chain reaction, Western blot and histological analyses. The CCK8 test was used to assess cell viability, and cell proliferation and apoptosis were evaluated by flow cytometric analysis. Results: Propofol, a gamma-aminobutyric acid (GABA) agonist widely used in general anesthesia, significantly changed the expr ession level of cAMP response element-binding protein (CREB) and B cell lymphoma 2 (Bcl2) and solute carrier family 1 member 3 (Slc1a3), but not extracellular signal-regulated kinase 1/2 (ERK1/2). PC12 cells that were exposed to propofol for more than 6 h exhibited downregulation of RSK1. MSO aggravated the toxicity of propofol in PC12 cells via inhibition of the p90RSK1/CREB/Bcl2 signaling pathway.
Background: L-Methionine sulfoximine (MSO) inhibits glutamine synthesis in a rodent animal model, and its limited clinical use is implicitly associated with glutamate deprivation and neurotoxicity. The purpose of this experiment was to determine the effect of MSO on pheochromocytoma (PC12) cells and its interaction with propofol-induced neuro-apoptosis. Objective: To study the effects of MSO on cell viability following 100 μM propofol treatment and the impact of ribosomal S6 kinase 1 (RSK1) signaling on the PC12 cell line. Methods: PC12 cells were exposed to propofol-triggered neurotoxicity for 6 h and then subjected to MSO treatment. The gene and protein expression levels of members of the RSK1 signaling pathway were determined by real-time polymerase chain reaction, Western blot and histological analyses. The CCK8 test was used to assess cell viability, and cell proliferation and apoptosis were evaluated by flow cytometric analysis. Results: Propofol, a gamma-aminobutyric acid (GABA) agonist widely used in general anesthesia, significantly changed the expr ession level of cAMP response element-binding protein (CREB) and B cell lymphoma 2 (Bcl2) and solute carrier family 1 member 3 (Slc1a3), but not extracellular signal-regulated kinase 1/2 (ERK1/2). PC12 cells that were exposed to propofol for more than 6 h exhibited downregulation of RSK1. MSO aggravated the toxicity of propofol in PC12 cells via inhibition of the p90RSK1/CREB/Bcl2 signaling pathway.Synthesis, characterization, and biological evaluation of new spebrutinib analogues: potential candidates with enhanced activity and reduced toxicity profileshttps://peerj.com/preprints/277552019-05-242019-05-24Zaid M Jaber Al-ObaidiOmar F Abdul-RasheedMonther F MahdiAyad M R Raauf
Background: Cancer is regarded as an undoubtable major concern for both researchers and the general public because of its high mortality rates. While breast cancer has the highest incidence of malignancy globally, colon cancer also has high morbidity and mortality rates. Currently, researchers are working on designing, synthesizing, and biologically investigating the effects of some potential anticancer candidates.
Methods: The authors successfully synthesized and characterized two potential spebrutinib analogues. These analogues were evaluated with the employment of MCF-7, HCT116, and MDCK cell lines.
Results: With respect to the spebrutinib standard, one of these analogues had superior activity against the MCF-7 cell line (IC50; 10.744 µg/mL against 13.566 µg/mL for spebrutinib) and an enhanced toxicity profile on the MDCK cell line (IC50; 8.653 mg/mL against 4.011 mg/mL for spebrutinib).
Background: Cancer is regarded as an undoubtable major concern for both researchers and the general public because of its high mortality rates. While breast cancer has the highest incidence of malignancy globally, colon cancer also has high morbidity and mortality rates. Currently, researchers are working on designing, synthesizing, and biologically investigating the effects of some potential anticancer candidates.Methods: The authors successfully synthesized and characterized two potential spebrutinib analogues. These analogues were evaluated with the employment of MCF-7, HCT116, and MDCK cell lines.Results: With respect to the spebrutinib standard, one of these analogues had superior activity against the MCF-7 cell line (IC50; 10.744 µg/mL against 13.566 µg/mL for spebrutinib) and an enhanced toxicity profile on the MDCK cell line (IC50; 8.653 mg/mL against 4.011 mg/mL for spebrutinib).Age-associated changes of cytochrome P450 and related phase-2 gene/proteins in livers of ratshttps://peerj.com/preprints/276472019-04-112019-04-11Shangfu XuAnling HuLu XieJiajia LiuQin WuJie J Liu
Cytochrome P450s (CYPs) are phase-I metabolic enzymes playing important roles in drug metabolism, dietary chemicals and endogenous molecules. Age is a key factor influencing P450s expression. Thus, age-related changes of CYP 1-4 families and bile acid homeostasis-related CYPs, the corresponding nuclear receptors and a few phase-II genes were examined. Livers from male Sprague-Dawley rats at fetus (-2 d), neonates (1, 7, and 14 d), weanling (21 d), puberty (28 and 35 d), adulthood (60 and 180 d), and aging (540 and 800 d) were collected and subjected to qPCR analysis. Liver proteins from 14, 28, 60, 180, 540 and 800 days of age were also extracted for selected protein analysis by Western-blot. In general, there were three patterns of their expression: Some of the drug-metabolizing enzymes and related nuclear receptors were low in fetal and neonatal stage, increased with liver maturation and decreased quickly at aging (AhR, Cyp1a1, Cyp2b1, Cyp2b2, Cyp3a1, Cyp3a2, Ugt1a2); the majority of P450s (Cyp1a2, Cyp2c6, Cyp2c11, Cyp2d2, Cyp2e1, CAR, PXR, FXR, Cyp7a1, Cyp7b1. Cyp8b1, Cyp27a1, Ugt1a1, Sult1a1, Sult1a2) maintained relatively high levels throughout the adulthood, and decreased at 800 days of age; and some had an early peak between 7 and 14 days (CAR, PXR, PPARα, Cyp4a1, Ugt1a2). The protein expression of CYP1A2, CYP2B1, CYP2E1, CYP3A1, CYP4A1, and CYP7A1 corresponded the trend of mRNA changes. In summary, this study characterized three expression patterns of 16 CYPs, 5 nuclear receptors, and 4 phase-II genes during development and aging in rat liver, adding to our understanding of age-related CYP expression changes and age-related disorders.
Cytochrome P450s (CYPs) are phase-I metabolic enzymes playing important roles in drug metabolism, dietary chemicals and endogenous molecules. Age is a key factor influencing P450s expression. Thus, age-related changes of CYP 1-4 families and bile acid homeostasis-related CYPs, the corresponding nuclear receptors and a few phase-II genes were examined. Livers from male Sprague-Dawley rats at fetus (-2 d), neonates (1, 7, and 14 d), weanling (21 d), puberty (28 and 35 d), adulthood (60 and 180 d), and aging (540 and 800 d) were collected and subjected to qPCR analysis. Liver proteins from 14, 28, 60, 180, 540 and 800 days of age were also extracted for selected protein analysis by Western-blot. In general, there were three patterns of their expression: Some of the drug-metabolizing enzymes and related nuclear receptors were low in fetal and neonatal stage, increased with liver maturation and decreased quickly at aging (AhR, Cyp1a1, Cyp2b1, Cyp2b2, Cyp3a1, Cyp3a2, Ugt1a2); the majority of P450s (Cyp1a2, Cyp2c6, Cyp2c11, Cyp2d2, Cyp2e1, CAR, PXR, FXR, Cyp7a1, Cyp7b1. Cyp8b1, Cyp27a1, Ugt1a1, Sult1a1, Sult1a2) maintained relatively high levels throughout the adulthood, and decreased at 800 days of age; and some had an early peak between 7 and 14 days (CAR, PXR, PPARα, Cyp4a1, Ugt1a2). The protein expression of CYP1A2, CYP2B1, CYP2E1, CYP3A1, CYP4A1, and CYP7A1 corresponded the trend of mRNA changes. In summary, this study characterized three expression patterns of 16 CYPs, 5 nuclear receptors, and 4 phase-II genes during development and aging in rat liver, adding to our understanding of age-related CYP expression changes and age-related disorders.A comparison of acute toxicity methodologies for Bombus spp.https://peerj.com/preprints/274362018-12-182018-12-18Kayla MundyNigel E. Raine
Acute toxicity testing (lethal dose and lethal concentration for 50% of the population; LD50 and LC50) is a required component of the first level of pesticide risk assessment. A review of peer-reviewed and ECOTOX database toxicity values was conducted to assess methodology and toxicity value consistency. Bumble bee LD50 and LC50 tests varied in five key areas: test subject, active ingredient specifications, test solution specifications, test conditions, test procedure. Only recently has a consistent methodology for bumble bee LD50 tests been released, but differs substantially from previous methods. Study methodologies have varied in at least one component and comparison of acute toxicity values can differ substantially between studies. Although a current standard, the appropriateness of the contact LD50 method of anaesthetisation and test location should be revisited. This work demonstrates inconsistency in current peer-reviewed analysis of acute toxicity to bumble bees and that current standard methods may not be perfected.
Acute toxicity testing (lethal dose and lethal concentration for 50% of the population; LD50 and LC50) is a required component of the first level of pesticide risk assessment. A review of peer-reviewed and ECOTOX database toxicity values was conducted to assess methodology and toxicity value consistency. Bumble bee LD50 and LC50 tests varied in five key areas: test subject, active ingredient specifications, test solution specifications, test conditions, test procedure. Only recently has a consistent methodology for bumble bee LD50 tests been released, but differs substantially from previous methods. Study methodologies have varied in at least one component and comparison of acute toxicity values can differ substantially between studies. Although a current standard, the appropriateness of the contact LD50 method of anaesthetisation and test location should be revisited. This work demonstrates inconsistency in current peer-reviewed analysis of acute toxicity to bumble bees and that current standard methods may not be perfected.Toxicity of Melaleuca alternifolia essential oil to the mitochondrion and NAD+/NADH dehydrogenase in Tribolium confusumhttps://peerj.com/preprints/271422018-08-272018-08-27Min LiaoQian-Qian YangJin-Jing XiaoYong HuangLi-Jun ZhouRi-Mao HuaHai-Qun Cao
Background. In our previous study, Melaleuca alternifolia essential oil (EO) was considered to have an insecticidal effect by acting on the mitochondrial respiratory chain in insects. However, the mode of action is not fully understood.
Methods. In this study, we investigated the insecticidal efficacy of the M. alternifolia EO against another major stored-product pest, Tribolium confusum Jacquelin du Val. Rarefaction and vacuolization of the mitochondrial matrix were evident in oil-fumigated T. confusum adults. Results. Alterations to the mitochondria confirmed the insecticidal effect of the M. alternifolia EO. Furthermore, comparative transcriptome analysis of T. confusum using RNA-seq indicated that most of the differentially expressed genes were involved in insecticide detoxification and mitochondrial function. The biochemical analysis showed that the intracellular NAD+/NADH ratio is involved in the differential effect of the M. alternifolia EO. Discussion. These results led us to conclude that NAD+/NADH dehydrogenase may be the prime target site for the M. alternifolia EO in insects, leading to blocking of the mitochondrial respiratory chain.
Background. In our previous study, Melaleuca alternifolia essential oil (EO) was considered to have an insecticidal effect by acting on the mitochondrial respiratory chain in insects. However, the mode of action is not fully understood.Methods. In this study, we investigated the insecticidal efficacy of the M. alternifolia EO against another major stored-product pest, Tribolium confusum Jacquelin du Val. Rarefaction and vacuolization of the mitochondrial matrix were evident in oil-fumigated T. confusum adults.Results. Alterations to the mitochondria confirmed the insecticidal effect of the M. alternifolia EO. Furthermore, comparative transcriptome analysis of T. confusum using RNA-seq indicated that most of the differentially expressed genes were involved in insecticide detoxification and mitochondrial function. The biochemical analysis showed that the intracellular NAD+/NADH ratio is involved in the differential effect of the M. alternifolia EO. Discussion. These results led us to conclude that NAD+/NADH dehydrogenase may be the prime target site for the M. alternifolia EO in insects, leading to blocking of the mitochondrial respiratory chain.Th2 cytokine bias induced by silver nanoparticles in peripheral blood mononuclear cells of common bottlenose dolphins (Tursiops truncatus)https://peerj.com/preprints/270492018-07-232018-07-23Wen-Ta LiLei-Ya WangHui-Wen ChangWei-Cheng YangChieh LoVictor Fei PangMeng-Hsien ChenChian-Ren Jeng
Background Silver nanoparticles (AgNPs) have been widely used in many commercial products due to their excellent antibacterial ability. The AgNPs are released into the environment, gradually accumulate in the ocean, and may affect animals at high trophic level, such as cetaceans and humans, via the food chain. Hence, the negative health impacts caused by AgNPs in cetaceans are of concern. Cytokines play a major role in the modulation of immune system and can be classified into two types, Th1 and Th2. Th1/Th2 balance can be evaluated by the ratios of their polarizing cytokines (i.e., interferon [IFN]-γ/ Interleukin [IL]-4), and animals with imbalanced Th1/Th2 response may become more susceptible to certain kinds of infection. Therefore, the present study evaluated the in vitro cytokine responses of cetacean peripheral blood mononuclear cells (cPBMCs) to 20 nm citrate-AgNPs (C-AgNP20) by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).
Methods Blood samples were collected from 6 captive common bottlenose dolphins (Tursiops truncatus). The cPBMCs were isolated and utilized for evaluating the in vitro cytokine responses. The cytokines evaluated included IL-2, IL-4, IL-10, IL-12, interferon (IFN)-γ, and tumor necrosis factor (TNF)-ɑ. The geometric means of two housekeeping genes (HKGs), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and β2-microglobulin (B2M), of each sample were determined and used to normalize the mRNA expression levels of target genes.
Results The ratio of late apoptotic/necrotic cells of cPBMCs significantly increased with or without concanavalin A (ConA) stimulation after 24 h of 10 μg/ml C-AgNP20 treatment. At 4 h of culture, the mRNA expression level of IL-10 was significantly decreased with 1 μg/ml C-AgNP20 treatment. At 24 h of culture with 1 μg/ml C-AgNP20, the mRNA expression levels of all cytokines were significantly decreased, with the exceptions of IL-4 and IL-10. The IFN-γ/IL-4 ratio was significantly decreased at 24 h of culture with 1 μg/ml C-AgNP20 treatment, and the IL-12/IL-4 ratio was significantly decreased at 4 or 24 h of culture with 0.1 or 1 μg/ml C-AgNP20 treatment, respectively. Furthermore, the mRNA expression level of TNF-α was significantly decreased by 1 μg/ml C-AgNP20 after 24 h of culture.
Discussion The present study demonstrated that the sublethal dose of C-AgNP20 (≤ 1 μg/ml) had an inhibitory effect on the cytokine mRNA expression levels of cPBMCs with the evidence of Th2 cytokine bias and significantly decreased the mRNA expression level of TNF-α. Th2 cytokine bias is associated with enhanced immunity against parasites but decreased immunity to intracellular microorganisms. TNF-α is a contributing factor for the inflammatory response against the infection of intracellular pathogens. In summary, our data indicate that C-AgNP20 suppresses the cellular immune response and thereby increases the susceptibility of cetaceans to infection by intracellular microorganisms.
Background Silver nanoparticles (AgNPs) have been widely used in many commercial products due to their excellent antibacterial ability. The AgNPs are released into the environment, gradually accumulate in the ocean, and may affect animals at high trophic level, such as cetaceans and humans, via the food chain. Hence, the negative health impacts caused by AgNPs in cetaceans are of concern. Cytokines play a major role in the modulation of immune system and can be classified into two types, Th1 and Th2. Th1/Th2 balance can be evaluated by the ratios of their polarizing cytokines (i.e., interferon [IFN]-γ/ Interleukin [IL]-4), and animals with imbalanced Th1/Th2 response may become more susceptible to certain kinds of infection. Therefore, the present study evaluated the in vitro cytokine responses of cetacean peripheral blood mononuclear cells (cPBMCs) to 20 nm citrate-AgNPs (C-AgNP20) by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR).Methods Blood samples were collected from 6 captive common bottlenose dolphins (Tursiops truncatus). The cPBMCs were isolated and utilized for evaluating the in vitro cytokine responses. The cytokines evaluated included IL-2, IL-4, IL-10, IL-12, interferon (IFN)-γ, and tumor necrosis factor (TNF)-ɑ. The geometric means of two housekeeping genes (HKGs), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and β2-microglobulin (B2M), of each sample were determined and used to normalize the mRNA expression levels of target genes.Results The ratio of late apoptotic/necrotic cells of cPBMCs significantly increased with or without concanavalin A (ConA) stimulation after 24 h of 10 μg/ml C-AgNP20 treatment. At 4 h of culture, the mRNA expression level of IL-10 was significantly decreased with 1 μg/ml C-AgNP20 treatment. At 24 h of culture with 1 μg/ml C-AgNP20, the mRNA expression levels of all cytokines were significantly decreased, with the exceptions of IL-4 and IL-10. The IFN-γ/IL-4 ratio was significantly decreased at 24 h of culture with 1 μg/ml C-AgNP20 treatment, and the IL-12/IL-4 ratio was significantly decreased at 4 or 24 h of culture with 0.1 or 1 μg/ml C-AgNP20 treatment, respectively. Furthermore, the mRNA expression level of TNF-α was significantly decreased by 1 μg/ml C-AgNP20 after 24 h of culture.Discussion The present study demonstrated that the sublethal dose of C-AgNP20 (≤ 1 μg/ml) had an inhibitory effect on the cytokine mRNA expression levels of cPBMCs with the evidence of Th2 cytokine bias and significantly decreased the mRNA expression level of TNF-α. Th2 cytokine bias is associated with enhanced immunity against parasites but decreased immunity to intracellular microorganisms. TNF-α is a contributing factor for the inflammatory response against the infection of intracellular pathogens. In summary, our data indicate that C-AgNP20 suppresses the cellular immune response and thereby increases the susceptibility of cetaceans to infection by intracellular microorganisms.Chemicals associated with plastic packaging: Inventory and hazardshttps://peerj.com/preprints/270362018-07-132018-07-13Ksenia J GrohThomas BackhausBethanie Carney-AlmrothBirgit GeuekePedro A InostrozaAnna LennquistMaricel MaffiniHeather A LeslieDaniel SlungeLeonardo TrasandeMichael WarhurstJane Muncke
Global plastics production has reached 380 million metric tons in 2015, with around 40% used for packaging. Plastic packaging is diverse and made of multiple polymers and numerous additives, along with other components, such as adhesives or coatings. Further, packaging can contain residues from substances used during manufacturing, such as solvents, along with non-intentionally added substances (NIAS), such as impurities, oligomers, or degradation products. To characterize risks from chemicals potentially released during manufacturing, use, disposal, and/or recycling of packaging, comprehensive information on all chemicals involved is needed. Here, we present a database of Chemicals associated with Plastic Packaging (CPPdb), which includes chemicals used during manufacturing and/or present in final packaging articles. The CPPdb lists 906 chemicals likely associated with plastic packaging and 3377 substances that are possibly associated. Of the 906 chemicals likely associated with plastic packaging, 63 rank highest for human health hazards and 68 for environmental hazards according to the harmonized hazard classifications assigned by the European Chemicals Agency within the Classification, Labeling and Packaging (CLP) regulation implementing the United Nations’ Globally Harmonized System (GHS). Further, 7 of the 906 substances are classified in the European Union as persistent, bioaccumulative, and toxic (PBT), or very persistent, very bioaccumulative (vPvB), and 15 as endocrine disrupting chemicals (EDC). Thirty-four of the 906 chemicals are also recognized as EDC or potential EDC in the recent EDC report by the United Nations Environment Programme. The identified hazardous chemicals are used in plastics as monomers, intermediates, solvents, surfactants, plasticizers, stabilizers, biocides, flame retardants, accelerators, and colorants, among other functions. Our work was challenged by a lack of transparency and incompleteness of publicly available information on both the use and toxicity of numerous substances. The most hazardous chemicals identified here should be assessed in detail as potential candidates for substitution.
Global plastics production has reached 380 million metric tons in 2015, with around 40% used for packaging. Plastic packaging is diverse and made of multiple polymers and numerous additives, along with other components, such as adhesives or coatings. Further, packaging can contain residues from substances used during manufacturing, such as solvents, along with non-intentionally added substances (NIAS), such as impurities, oligomers, or degradation products. To characterize risks from chemicals potentially released during manufacturing, use, disposal, and/or recycling of packaging, comprehensive information on all chemicals involved is needed. Here, we present a database of Chemicals associated with Plastic Packaging (CPPdb), which includes chemicals used during manufacturing and/or present in final packaging articles. The CPPdb lists 906 chemicals likely associated with plastic packaging and 3377 substances that are possibly associated. Of the 906 chemicals likely associated with plastic packaging, 63 rank highest for human health hazards and 68 for environmental hazards according to the harmonized hazard classifications assigned by the European Chemicals Agency within the Classification, Labeling and Packaging (CLP) regulation implementing the United Nations’ Globally Harmonized System (GHS). Further, 7 of the 906 substances are classified in the European Union as persistent, bioaccumulative, and toxic (PBT), or very persistent, very bioaccumulative (vPvB), and 15 as endocrine disrupting chemicals (EDC). Thirty-four of the 906 chemicals are also recognized as EDC or potential EDC in the recent EDC report by the United Nations Environment Programme. The identified hazardous chemicals are used in plastics as monomers, intermediates, solvents, surfactants, plasticizers, stabilizers, biocides, flame retardants, accelerators, and colorants, among other functions. Our work was challenged by a lack of transparency and incompleteness of publicly available information on both the use and toxicity of numerous substances. The most hazardous chemicals identified here should be assessed in detail as potential candidates for substitution.