Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 144
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Anticancer Res ; 40(4): 2053-2057, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32234896

RESUMO

BACKGROUND: The present study aimed to evaluate the toxicity and efficacy of stereotactic body radiotherapy (SBRT) for localized prostate cancer. PATIENTS AND METHODS: We investigated 25 patients treated with SBRT of 35 Gy per five fractions from May 2014 to March 2015. RESULTS: The median age of patients was 70 years, four (16%) patients were low risk and 21 (84%) were intermediate risk. Seven (28%) patients received neoadjuvant androgen-deprivation therapy. The median follow-up time was 53 months. Grade 2 acute and late genitourinary toxicities were observed in five (20%) and two (8%) patients and there were no Grade 2 gastrointestinal toxicities. There were no Grade 3 or higher acute or late toxicities at 2 years follow-up. The biochemical relapse-free survival rate at 2 years was 100%. CONCLUSION: SBRT of 35 Gy per five fractions is a promising treatment method in the short term for prostate cancer.


Assuntos
Androgênios/metabolismo , Trato Gastrointestinal/efeitos dos fármacos , Neoplasias da Próstata/radioterapia , Radiocirurgia/efeitos adversos , Idoso , Idoso de 80 Anos ou mais , Antagonistas de Androgênios/administração & dosagem , Antineoplásicos Hormonais/administração & dosagem , Fracionamento da Dose de Radiação , Trato Gastrointestinal/patologia , Humanos , Masculino , Terapia Neoadjuvante , Próstata/patologia , Próstata/efeitos da radiação , Antígeno Prostático Específico/metabolismo , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/patologia , Planejamento da Radioterapia Assistida por Computador , Medição de Risco , Resultado do Tratamento
2.
Biochem Biophys Res Commun ; 526(1): 206-212, 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32201079

RESUMO

Gadolinium-based contrast agents (GBCAs) are widely used in clinical magnetic resonance imaging (MRI). Free gadolinium ions (Gd3+) released from GBCAs potentially increase the risk of GBCA-related toxicity. However, the cellular responses to Gd3+ and the underlying mechanisms responsible for protection against Gd3+ remain poorly understood. Recently, autophagy has been considered a cell survival mechanism against various toxic metals. Here, we investigated the relationship between Gd3+ and autophagy, as well as the effect of autophagy inhibition on the survival of cells exposed to Gd3+. We found that the increased expression of microtubule-associated protein 1 light chain 3 (LC3)-II, a marker protein of autophagy, in Gd3+-exposed human embryonic kidney 293 (HEK293) cells. Moreover, we found a greater accumulation of LC3-II after exposure to an autophagy inhibitor, chloroquine (CQ), combined with Gd3+ than that after exposure to CQ alone, suggesting that Gd3+ activated autophagy in HEK293 cells. Furthermore, we found that Gd3+ reduced cell viability, which was more pronounced after CQ treatment. Our findings indicated that autophagy exerted a cytoprotective effect against Gd3+ toxicity, suggesting a potential link between autophagy and GBCA-associated adverse events.

4.
J Plant Res ; 133(2): 271-277, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31897741

RESUMO

Studies of plant-silicon (Si) interaction benefit from safe, affordable and accurate methods to measure acid-insoluble silica (phytoliths) for a large number of plant samples. This study aimed to evaluate the comparability between two chemical methods to dissolve leaf silica, borate fusion and 1% sodium carbonate (Na2CO3) extraction, in combination of two detection methods (ICP, molybdenum-blue colorimetry).We compared the results obtained by these methods, using dried leaf samples of five tropical tree species that differ widely in Si concentrations (4 to 100 mg g DW-1). Leaf Si concentration values determined after the two extraction methods were highly correlated (y = 0.79x, R2 = 0.998). However, compared to the extraction with borate fusion, the 1% Na2CO3 method resulted in lower Si concentration per unit dry mass by 16% to 32% (mean of 24.2%). We also found that molybdenum-blue colorimetry method may interfere with certain extraction methods. A simple equation can be used to correct for systematic underestimation of Si contents determined after extraction with 1% Na2CO3, which is the least expensive and safest among commonly used methods for extraction of Si from land plants.

6.
Anat Rec (Hoboken) ; 303(3): 471-477, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30809962

RESUMO

The tracheal lumen is essential for conducting air to the lung alveoli and for voice production. However, patients with severe tracheal stenosis and malignant tumors invading the trachea often require tracheal resection. Recently, various reported tissue engineering methods for tracheal reconstruction show that regeneration of ciliated epithelium in the reconstructed areas, as well as preservation of the luminal structure is possible. However, only few studies report on the mucociliary transport function in reconstructed tracheae. We investigated mucociliary transport function within rat tracheal epithelium, reorganized after autologous adipose tissue-derived stem cell (ASC) transplantation. Rat ASCs were expanded in culture, and then seeded in a collagen sponge, which was physically supported with a polypropylene framework. The ASC-seeded collagen sponge was transplanted into the rat tracheal defect. We then examined the motility and transport function of cilia generated in the transplanted area using ciliary beat frequency (CBF) and microsphere movement analyses. Our data suggested that autologous ASC transplantation promoted ciliogenesis, consistent with previous reports. The CBF analysis revealed that motility of the cilia generated in the ASC group was comparable to that observed in the normal rat tracheal epithelium. Transport function in the ASC group was higher than that in the control group. These data suggested that autologous ASC transplantation increased ciliated cells in the reconstructed area without significantly disrupting cilia motility, thereby promoting transport function regeneration. Autologous ASC transplantation is expected to be beneficial in morphological and functional regeneration of tracheal epithelium. Anat Rec, 303:471-477, 2020. © 2019 American Association for Anatomy.

7.
Laryngoscope ; 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31804718

RESUMO

OBJECTIVES/HYPOTHESIS: To regenerate defected recurrent laryngeal nerves (RLNs), various methods have been developed. However, no consistently effective treatments are currently available because of their insufficient functional recovery. RADA16-I, a self-assembling peptide used clinically as a hemostat, reportedly supports neurite outgrowth and functional synapse formation in vitro. The purpose of this study was to investigate the effect of RADA16-I hydrogels on transected RLNs in rats. STUDY DESIGN: Animal experiments with controls. METHODS: Fifteen adult rats were divided into the following three groups: RADA16-I (+), RADA16-I (-), and neurectomy. A 6-mm gap of the left RLN was bridged using an 8-mm silicone tube in the RADA16-I (-) and RADA16-I (+) groups. Subsequently, RADA16-I hydrogel was injected into the tube in the RADA16-I (+) group. The surgical incisions were closed without any further treatment in the neurectomy group. After 8 weeks, laryngoscopy and electrophysiological and histological examinations were performed to evaluate the effect of RADA16-I on nerve regeneration and thyroarytenoid muscle atrophy. RESULTS: Although most rats in the three groups exhibited no improvements of their vocal fold movement, partial recovery was observed in one rat in the RADA16-I (+) group. The neurofilament-positive areas and the number of myelinated nerves in the RADA16-I (+) group were significantly higher than in the RADA16-I (-) group. The area of the left thyroarytenoid muscle in the RADA16-I (+) group was significantly larger than that of the neurectomy group. CONCLUSIONS: Our results suggested that RADA16-I hydrogel was effective for RLN regeneration. LEVEL OF EVIDENCE: NA Laryngoscope, 2019.

8.
Yakugaku Zasshi ; 139(12): 1557-1562, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-31787645

RESUMO

Severe cutaneous adverse reactions (SCARs) are important in postmarketing drug safety because SCAR patients were highest in the adverse drug reaction relief system of Japan. The SCAR symptoms of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) include high fever, severe mucosal impairment, and epidermal necrosis-induced erosions and blisters. Approximately 600 cases of SJS and 300 cases of TEN are reported annually in Japan. Many suspected drugs such as acetaminophen, lamotrigine, allopurinol, and carbamazepine have been reported. Over the last 15 years, an association between human leukocyte antigen and SJS/TEN onset has been reported with several drugs. Pathophysiological examinations in those reports revealed marked CD8-positive T cell infiltration into epidermal lesions, and the presence of cytotoxic granulysin, soluble Fas ligand, and tumor necrosis factor (TNF)-α in blister fluid. Therefore, SJS and TEN are immunological disorders that lead to epidermal necrosis and are consequently treated with the systemic administration of corticosteroids and with high-dose intravenous immunoglobulin therapy and plasma exchange in severe cases. Additionally, because the epidermal necrosis has characteristics similar to those of organ rejection after transplantation, the administration of cyclosporine, an immunosuppressant that inhibits helper T cell activation, has been attempted. Further, the administration of the TNF-α inhibitor etanercept has also been reported. This review summarizes current knowledge on the mechanisms of onset of SJS/TEN and their treatments.


Assuntos
Acetaminofen/efeitos adversos , Alopurinol/efeitos adversos , Carbamazepina/efeitos adversos , Lamotrigina/efeitos adversos , Síndrome de Stevens-Johnson/etiologia , Corticosteroides/uso terapêutico , Antígenos de Diferenciação de Linfócitos T , Linfócitos T CD8-Positivos/imunologia , Ciclosporina/uso terapêutico , Epiderme/imunologia , Etanercepte/uso terapêutico , Proteína Ligante Fas , Antígenos HLA , Humanos , Imunoglobulinas Intravenosas/uso terapêutico , Imunossupressores/uso terapêutico , Japão/epidemiologia , Troca Plasmática , Síndrome de Stevens-Johnson/epidemiologia , Síndrome de Stevens-Johnson/terapia , Fator de Necrose Tumoral alfa
9.
Opt Express ; 27(26): 38019-38027, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31878573

RESUMO

The orbital angular momentum of an optical vortex field is found to twist high viscosity donor material to form a micron-scale 'spin jet'. This unique phenomenon manifests the helical trajectory of the optical vortex. Going beyond both the conventional ink jet and laser induced forward mass transfer (LIFT) patterning technologies, it also offers the formation and ejection of a micron-scale 'spin jet' of the donor material even with an ultrahigh viscosity of 4 Pa·s. This optical vortex laser induced forward mass transfer (OV-LIFT) patterning technique will enable the development of next generation printed photonic/electric/spintronic circuits formed of ultrahigh viscosity donor dots containing functional nanoparticles, such as quantum dots, metallic particles and magnetic ferrite particles, with ultrahigh spatial resolution. It can also potentially explore a completely new needleless drug injection.

10.
Artigo em Inglês | MEDLINE | ID: mdl-31775017

RESUMO

BACKGROUND: CD23 mediates IgE-facilitated allergen presentation and subsequent allergen-specific T-cell activation in allergic patients. OBJECTIVE: We sought to investigate key factors regulating IgE-facilitated allergen presentation through CD23 and subsequent T-cell activation. METHODS: To study T-cell activation by free allergens and different types of IgE-Bet v 1 complexes, we used a molecular model based on monoclonal human Bet v 1-specific IgE, monomeric and oligomeric Bet v 1 allergen, an MHC-matched CD23-expressing B-cell line, and a T-cell line expressing a human Bet v 1-specific T-cell receptor. The ability to cross-link Fcε receptors of complexes consisting of either IgE and monomeric Bet v 1 or IgE and oligomeric Bet v 1 was studied in human FcεRI-expressing basophils. T-cell proliferation by monomeric or oligomeric Bet v 1, which cross-links Fcε receptors to a different extent, was studied in allergic patients' PBMCs with and without CD23-expressing B cells. RESULTS: In our model non-cross-linking IgE-Bet v 1 monomer complexes, as well as cross-linking IgE-Bet v 1 oligomer complexes, induced T-cell activation, which was dependent on the concentration of specific IgE. However, T-cell activation by cross-linking IgE-Bet v 1 oligomer complexes was approximately 125-fold more efficient. Relevant T-cell proliferation occurred in allergic patients' PBMCs only in the presence of B cells, and its magnitude depended on the ability of IgE-Bet v 1 complexes to cross-link CD23. CONCLUSION: The extent of CD23-mediated T-cell activation depends on the concentration of allergen-specific IgE and the cross-linking ability of IgE-allergen complexes.

11.
PLoS One ; 14(11): e0217451, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31682640

RESUMO

The epithelial-mesenchymal transition (EMT) is a crucial morphological event that occurs during epithelial tumor progression. ZEB1/2 are EMT transcription factors that are positively correlated with EMT phenotypes and breast cancer aggressiveness. ZEB1/2 regulate the alternative splicing and hence isoform switching of fibroblast growth factor receptors (FGFRs) by repressing the epithelial splicing regulatory proteins, ESRP1 and ESRP2. Here, we show that the mesenchymal-like phenotypes of oral squamous cell carcinoma (OSCC) cells are dependent on autocrine FGF-FGFR signaling. Mesenchymal-like OSCC cells express low levels of ESRP1/2 and high levels of ZEB1/2, resulting in constitutive expression of the IIIc-isoform of FGFR, FGFR(IIIc). By contrast, epithelial-like OSCC cells showed opposite expression profiles for these proteins and constitutive expression of the IIIb-isoform of FGFR2, FGFR2(IIIb). Importantly, ERK1/2 was constitutively phosphorylated through FGFR1(IIIc), which was activated by factors secreted autonomously by mesenchymal-like OSCC cells and involved in sustained high-level expression of ZEB1. Antagonizing FGFR1 with either inhibitors or siRNAs considerably repressed ZEB1 expression and restored epithelial-like traits. Therefore, autocrine FGF-FGFR(IIIc) signaling appears to be responsible for sustaining ZEB1/2 at high levels and the EMT phenotype in OSCC cells.

12.
Hum Genome Var ; 6: 50, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31666976

RESUMO

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are acute-onset mucocutaneous diseases induced by infectious agents and/or inciting drugs. We have reported that the main causative drugs for SJS/TEN with severe ocular complications (SOC) were cold medicines, including multi-ingredient cold medications and nonsteroidal anti-inflammatory drugs (NSAIDs). Moreover, we also reported that acetaminophen is the most frequent causative drug in various cold medicines. In this study, we focused on acetaminophen-related SJS/TEN with SOC and analyzed HLA-class II (HLA-DRB1, DQB1) in addition to HLA-class I (HLA-A, B, C). We studied the histocompatibility antigen genes HLA-DRB1 and DQB1 in addition to HLA-A, B, and C in 80 Japanese patients with acetaminophen-related SJS/TEN with SOC. We performed polymerase chain reaction amplification followed by hybridization with sequence-specific oligonucleotide probes (PCR-SSO) using commercial bead-based typing kits. We also used genotyped data from 113 healthy volunteers for HLA-DRB1 and DQB1, and 639 healthy volunteers for HLA-A, B, and C. HLA-DRB1*08:03 and DRB1*12:02 were associated with acetaminophen-related SJS/TEN with SOC, although the results ceased to be significant when we corrected the p-value for the number of alleles detected. HLA-A*02:06 was strongly associated with acetaminophen-related SJS/TEN with SOC (carrier frequency: p = 4.7 × 10-12, Pc = 6.6 × 10-11, OR = 6.0; gene frequency: p = 8.0 × 10-13, Pc = 1.1 × 10-11, OR = 4.9). HLA-B*13:01 (carrier frequency: p = 2.0 × 10-3, Pc = 0.042, OR = 4.1; gene frequency: p = 2.2 × 10-3, Pc = 0.047, OR = 3.9), HLA-B*44:03 (carrier frequency: p = 2.1 × 10-3, Pc = 0.045, OR = 2.4) and HLA-C*14:03 (carrier frequency: p = 3.4 × 10-3, Pc = 0.045, OR = 2.3) were also significantly associated, while HLA-A*24:02 was inversely associated (gene frequency: p = 6.3 × 10-4, Pc = 8.8 × 10-3, OR = 0.5). Acetaminophen-related SJS/TEN with SOC was not associated with HLA-class II (HLA-DRB1, DQB1). However, for acetaminophen-related SJS/TEN with SOC, we found an association with HLA-B*13:01 and HLA- C*14:03 in addition to HLA-A*02:06 and HLA-B*44:03, which have been described previously.

13.
Artigo em Inglês | MEDLINE | ID: mdl-31711791

RESUMO

INTRODUCTION: Postoperative dysphonia is mostly caused by vocal fold scarring, and careful management of vocal fold surgery has been reported to reduce the risk of scar formation. However, depending on the vocal fold injury, treatment of postoperative dysphonia can be challenging. OBJECTIVE: The goal of the current study was to develop a novel prophylactic regenerative approach for the treatment of injured vocal folds after surgery, using biodegradable gelatin hydrogel microspheres as a drug delivery system for basic fibroblast growth factor. METHODS: Videoendoscopic laryngeal surgery was performed to create vocal fold injury in 14 rabbits. Immediately following this procedure, biodegradable gelatin hydrogel microspheres with basic fibroblast growth factor were injected in the vocal fold. Two weeks after injection, larynges were excised for evaluation of vocal fold histology and mucosal movement. RESULTS: The presence of poor vibratory function was confirmed in the injured vocal folds. Histology and digital image analysis demonstrated that the injured vocal folds injected with gelatin hydrogel microspheres with basic fibroblast growth factor showed less scar formation, compared to the injured vocal folds injected with gelatin hydrogel microspheres only, or those without any injection. CONCLUSION: A prophylactic injection of basic fibroblast growth factor -containing biodegradable gelatin hydrogel microspheres demonstrates a regenerative potential for injured vocal folds in a rabbit model.

14.
FEBS J ; 2019 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-31587510

RESUMO

Cysteine desulfurase enzymes catalyze sulfur mobilization from l-cysteine to sulfur-containing biomolecules such as iron-sulfur (Fe-S) clusters and thio-tRNAs. The enzymes utilize the cofactor pyridoxal-5'-phosphate (PLP), which forms the external substrate- and product-aldimines and ketimines during catalysis and are grouped into two types (I and II) based on their different catalytic loops. To clarify the structure-based catalytic mechanisms for each group, we determined the structures of the external substrate- and product-aldimines as catalytic intermediates of NifS (type I) and SufS (type II) that are involved in Fe-S cluster biosynthesis using X-ray crystallographic snapshot analysis. As a common intermediate structure, the thiol group of the PLP-l-cysteine external aldimine is stabilized by the conserved histidine adjacent to PLP through a polar interaction. This interaction makes the thiol group orientated for subsequent nucleophilic attack by a conserved cysteine residue on the catalytic loop in the state of PLP-l-cysteine ketimine, which is formed from the PLP-l-cysteine aldimine. Unlike the intermediates, structural changes of the loops were different between the type I and II enzymes. In the type I enzyme, conformational and topological change of the loop is necessary for nucleophilic attack by the cysteine. In contrast, the loop in type II cysteine desulfurase enzymes showed no large conformational change; rather, it might possibly orient the thiol group of the catalytic cysteine for nucleophilic attack toward PLP-l-cysteine. The present structures allow a revision of the catalytic mechanism and may provide a clue for consideration of enzyme function, structural diversity, and evolution of cysteine desulfurase enzymes. DATABASE: Structural data are available in PDB database under the accession numbers 5WT2, 5WT4, 5ZSP, 5ZST, 5ZS9, 5ZSK, 5ZSO, 6KFZ, 6KG0, and 6KG1.

15.
PLoS One ; 14(8): e0221034, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31430311

RESUMO

Several laboratories have created rat basophil leukemia (RBL) cell lines stably transfected with the human high affinity IgE receptor (FcεRIH). More recently, humanized RBL cell lines saw the introduction of reporter genes such as luciferase (RS-ATL8) and DsRed (RBL NFAT-DsRed). These reporters are more sensitive than their parental non-reporter humanized RBL cell lines. However, no studies so far have addressed the levels of FcεRIH surface expression on humanized RBL cell lines. This is a critical parameter, as it determines the ability of these cells to be efficiently sensitized with human IgE, hence it should affect the sensitivity of the cell assay-a critical parameter for any diagnostic application. Our purpose was to assess and compare the levels of expression of the transfected FcεRIH chain in humanized RBL cell lines. We compared surface levels of FcεRIαH by flow cytometry, using a fluorescently labelled monoclonal antibody (CRA-1/AER-37) and determined receptor numbers using calibration microspheres. FcεRIαH copy numbers were assessed by qPCR, and the sequence verified. Transfection with FcεRIγH cDNA was assessed for its ability to increase FcεRIαH expression in the NFAT-DsRed reporter. While both SX-38 and RS-ATL8 expressed about 500.000 receptors/cell, RBL 703-21 and NFAT-DsRed had approximately 10- to 30-fold lower FcεRIαH expression, respectively. This was neither related to FcεRIH gene copy numbers, nor to differences in steady state mRNA levels, as determined by qPCR and RT-qPCR, respectively. Instead, FcεRIαH surface expression appeared to correlate with the co-expression of FcεRIγH. Stable transfection of NFAT-DsRed cells with pBJ1 neo-huFcεRI gamma, which constitutively expresses FcεRIγH, increased FcεRIαH chain expression levels. Levels of FcεRIαH surface expression vary greatly between humanized RBL reporter cell lines. This difference will affect the sensitivity of the reporter system when used for diagnostic purposes.

16.
Planta ; 250(2): 667-674, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31104129

RESUMO

MAIN CONCLUSION: Mercury accumulation in Arabidopsis shoots is accelerated by endodermis specific expression of fusion proteins of a bacterial mercury transporter MerC and a plant SNARE SYP121 under control of SCARECROW promoter. We previously demonstrated that the CaMV 35S RNA promoter (p35S)-driven ubiquitous expression of a bacterial mercury transporter MerC, fused with SYP121, an Arabidopsis SNARE protein increases mercury accumulation of Arabidopsis. To establish an improved fine-tuned mercury transport system in plants for phytoremediation, the present study generated and characterized transgenic Arabidopsis plants expressing MerC-SYP121 specifically in the root endodermis, which is a crucial cell type for root element uptake. We generated four independent transgenic Arabidopsis lines expressing a transgene encoding mCherry-MerC-SYP121 under the control of the endodermis-specific SCARECROW promoter (hereafter pSCR lines). Quantitative real-time PCR analysis showed that expression levels of the transgene in roots of the pSCR lines were 3-23% of the p35S driven-overexpressing line. Confocal microscopy analysis showed that mCherry-MerC-SYP121 was dominantly expressed in the endodermis of the meristematic zone as well as in the mature zone of the pSCR roots. Mercury accumulation in shoots of the pSCR lines exposed to inorganic mercury was overall higher than the wild-type and comparable to the p35S over-expressing line. These results suggest that endodermis-specific expression of the MerC-SYP121 fusion proteins in plant roots sufficiently enhances mercury uptake and accumulation into shoots, which would be an ideal phenotype for phytoremediation of mercury-contaminated environments.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Mercúrio/metabolismo , Proteínas Qa-SNARE/metabolismo , Arabidopsis/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Transporte Biológico , Proteínas de Transporte de Cátions/genética , Meristema/genética , Meristema/metabolismo , Especificidade de Órgãos , Fenótipo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Brotos de Planta/genética , Brotos de Planta/metabolismo , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Proteínas Qa-SNARE/genética , Proteínas Recombinantes de Fusão
17.
Toxicol Sci ; 170(2): 438-451, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31046098

RESUMO

Some methylmercury (MeHg) is converted to inorganic mercury (Hg2+) after incorporation into human and animal tissues, where it can remain for a long time. To determine the overall toxicity of MeHg in tissues, studies should evaluate low concentrations of Hg2+. Although demethylation is involved, the participating enzymes or underlying mechanisms are unknown; in addition, the low cell membrane permeability of Hg2+ makes these analyses challenging. We established model cell lines to assess toxicities of low concentrations of Hg2+ using bacterial organomercury lyase (MerB). We engineered MerB-expressing HEK293 and HeLa cell lines that catalyze MeHg demethylation. These cells were significantly more sensitive to MeHg exposure compared to the parental cells. MeHg treatment remarkably induced metallothioneins (MTs) and hemeoxygenase-1 (HMOX-1) mRNAs and modest expression of superoxide dismutase 1, whereas catalase and glutathione peroxidase 1 mRNAs were not up-regulated. merB knockdown using small interfering RNA supported the induction of MT and HMOX-1 mRNA by MerB enzymatic activity. Pretreatment with Trolox, a water-soluble vitamin E analog, did not inhibit MeHg-induced elevation of MT-Ix and HMOX-1 mRNAs in MerB-expressing cells, suggesting that Hg2+ works independently of reactive oxygen species generation. Similar results were obtained in cells expressing MerB, suggesting that high MTs and HMOX-1 induction and cytotoxicity are common cellular responses to low intracellular Hg2+ concentrations. This is the first study to establish cell lines that demethylate intracellular MeHg to Hg2+ using bacterial MerB for overcoming the low membrane permeability of Hg2+ and exploring the intracellular responses and toxicities of low Hg2+ concentrations.

18.
Sci Rep ; 9(1): 4347, 2019 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-30867467

RESUMO

For mercury phytoextraction, we previously demonstrated in Arabidopsis thaliana that a constitutive and ubiquitous promoter-driven expression of a bacterial mercury transporter MerC fused with SYP121, a plant SNARE for plasma membrane protein trafficking increases plant mercury accumulation. To advance regulation of ectopic expression of the bacterial transporter in the plant system, the present study examined whether merC-SYP121 expression driven by a root epidermis specific promoter (pEpi) is sufficient to enhance mercury accumulation in plant tissues. We generated five independent transgenic Arabidopsis plant lines (hereafter pEpi lines) expressing a transgene encoding MerC-SYP121 N-terminally tagged with a fluorescent protein mTRQ2 under the control of pEpi, a root epidermal promoter. Confocal microscopy analysis of the pEpi lines showed that mTRQ2-MerC-SYP121 was preferentially expressed in lateral root cap in the root meristematic zone and epidermal cells in the elongation zone of the roots. Mercury accumulation in shoots of the pEpi lines exposed to inorganic mercury was overall higher than the wild-type and comparable to the over-expressing line. The results suggest that cell-type specific expression of the bacterial transporter MerC in plant roots sufficiently enhances mercury accumulation in shoots, which could be a useful phenotype for improving efficiency of mercury phytoremediation.

19.
Biochem Biophys Res Commun ; 511(2): 460-467, 2019 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-30797556

RESUMO

Methylmercury (MeHg) is a highly toxic pollutant, and is considered hazardous to human health. In our previous study, we found that MeHg induces autophagy and that Atg5-dependent autophagy plays a protective role against MeHg toxicity. To further characterize the role of autophagy in MeHg-induced toxicity, we examined the impact of autophagy on microtubules and nuclei under MeHg exposure using Atg5KO mouse embryonic fibroblasts (MEFs). Low concentrations of MeHg induced a decrease in α-tubulin and acetylated-tubulin in both wild-type and Atg5KO cells. While α-tubulin acetylation was promoted by treatment with tubacin, a selective inhibitor of histone deacetylase 6, MeHg treatment inhibits the increase of tubacin-induced acetylated-tubulin. However, similar effects were observed for treatment with either tubacin or tubacin + MeHg in wild-type and Atg5KO cells. We also found a significant increase in the number of multinuclear cells upon MeHg exposure in Atg5KO MEFs compared to wild-type MEFs. In addition, DNA double strand breaks (DSBs), measured by phosphorylation of the core histone H2A variant (H2AX) on serine 139 (γH2AX), markedly increased in Atg5KO MEFs compared to wild-type MEFs. Our results therefore suggest that autophagy is not a simple elimination pathway of MeHg-induced damaged proteins, but that it also plays a protective role in the context of MeHg-associated DSBs.


Assuntos
Autofagia/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Compostos de Metilmercúrio/toxicidade , Acetilação/efeitos dos fármacos , Anilidas/metabolismo , Animais , Linhagem Celular , Núcleo Celular/genética , Núcleo Celular/metabolismo , Núcleo Celular/patologia , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/patologia , Ácidos Hidroxâmicos/metabolismo , Camundongos , Tubulina (Proteína)/metabolismo
20.
J Cell Physiol ; 2019 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-30714154

RESUMO

Functional central airway epithelial cells (CAECs) from induced pluripotent stem cells (iPSCs) are an attractive potential cell source for central airway regeneration. The central airway epithelium, such as the tracheal epithelium, is composed of ciliated cells, goblet cells, and basal cells and has physiologically important functions such as the regulation of water volume on the airway surface by Cl- and water channels and the elimination of particles inhaled from the external environment by ciliary movement. Previous work from our group and from other research groups has reported the generation of airway epithelial cells from iPSCs. However, it remains unclear whether iPSC-derived CAECs express the various channels that are required for the regulation of water volume on the airway surface and whether these channels function properly. In this study, we generated CAECs from iPSCs supplemented with activin and bFGF using air-liquid interface culture. We then evaluated the physiological functioning of the iPSC-derived CAECs by examining the gene expression and transport functions of Cl - channels using a halide ion-sensitive yellow fluorescent protein and ciliary movement. Reverse-transcription polymerase chain reaction and immunohistochemistry indicated that various channel markers such as cystic fibrosis transmembrane conductance regulator (CFTR) and aquaporin (AQP) were present in iPSC-derived CAECs. Furthermore, the transport functions of Cl - channels and CFTR were successfully confirmed. Finally, ciliary movement was measured, and a ciliary beating frequency (CBF) of approximately 10 Hz was observed. These results demonstrate that CAECs generated by our method have physiological functions similar to those of native CAECs.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA