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1.
Sensors (Basel) ; 20(5)2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32110937

RESUMO

By contrast with the widely reported traditional two mirror-based Herriott cell, a three mirror-based dense pattern gas cell was proposed, of which the modeling and design were proven to be effective through a comparison between the simulated spot pattern and effective path length and those of the experimental results. A mechanical structure was designed to adjust the position/angle of the three mirrors for aligning the optical path. The experimentally measured reflection number was 60, resulting in an optical path length of ~11 m, which agrees well with the theoretical value of 10.95 m. Combined with a near-infrared laser with a center wavenumber located at an acetylene (C2H2) absorption line of 6521.2 cm-1, a C2H2 sensor system was established to verify the feasibility of the three mirror-based gas cell. Assisted by a data acquisition (DAQ) card, a LabVIEW platform was developed to generate the drive signal of the laser and acquire the second harmonic (2f) signal from the output of the detector. Through Allan variance analysis, the limit of detection (LoD) of the sensor system is 4.36 ppm at an average time of 0.5 s; as the average time exceeds 10 s, the LoD is <1 ppm. The proposed model and design of the three mirror-based gas cell can be used to realize similar gas cells with different absorption path lengths for gas detection based on infrared absorption spectroscopy.

2.
Biomater Sci ; 8(6): 1759-1770, 2020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32010909

RESUMO

Currently, bioengineered apoferritin nanocages with flexible protein shells and functionalized modifications have become an attractive approach for efficient anti-tumor therapy. Here, we modified the N-terminus of H-chain subunits in apoferritin with different amounts of lysine via genetic recombination to obtain a poly(l-lysine) modified H-chain apoferritin (nL-HFn) nanocage for siRNA delivery and gene therapy. To achieve excellent cellular affinity and uptake, the nanocarriers were internalized through transferrin receptor-mediated endocytosis, then escaped from the endosome for cytoplasmic transport. Compared with natural apoferritin, the siRNA-loaded genetic recombination NPs modified with lysine exhibit stronger RNA-interference and antitumor efficiency both in vitro and in 4T1 tumor model mice. Therefore, bioengineered apoferritin nanocages modified with lysine might be a promising platform for nucleic acid drug delivery.

3.
Sci Total Environ ; 712: 136480, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-31931206

RESUMO

Overexposure to manganese (Mn) can result in neurotoxicity and is associated with manganism, a Parkinson's-like neurological disorder. In addition, Mn can induce endoplasmic reticulum (ER) stress and autophagy. In this study, we used C57BL/6 mice to establish a model of manganism and found that Mn could induce cell injury. Our results also showed that Mn could initiate the unfolded protein response (UPR) signaling and autophagy, via initiation of the UPR signaling occurring earlier than autophagy. We further investigated the intrinsic relationship between the endoplasmic reticulum to nucleus 1(ERN1, also known as inositol requiring enzyme 1, IRE1) signaling pathway and autophagy induction in SH-SY5Y cells exposed to Mn. Our results revealed that autophagy activation was a protective response in Mn-induced toxicity. Additionally, we found that Jun N-terminal kinase (JNK) inhibition downregulated autophagy and interaction of c-Jun with the Beclin1 promoter. In addition, knockdown of IRE1 with the LV-IRE1 shRNA suppressed the expression of IRE1, TRAF2, p-ASK1, and p-JNK in Mn-treated SH-SY5Y cells. Furthermore, the expression of proteins associated with ASK1-TRAF2 complex formation and autophagy activation were reversed by the LV-IRE1 shRNA. These findings suggest that IRE1 was involved in the activation of JNK through the formation of the ASK1-TRAF2 complex, and JNK activation led to the induction of autophagy, which required Beclin1 transcription by c-Jun. In this study, we demonstrated that the IRE1 signaling pathway mediated the activation of JNK signaling via the formation of the ASK1-TRAF2 complex which could initiate autophagy and the protein c-Jun which regulates Beclin1 transcription in Mn-induced neurotoxicity.

4.
Bioorg Chem ; 96: 103536, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31972463

RESUMO

Angiogenesis is known to serve an important role in embryonic development, wound healing, tissue regeneration, and growth. Two new abietane-type diterpenoids (3, 5), a new lanosterol triterpenoid (8) and seven known compounds haven been isolated from the Euphorbia neriifolia Linn. The structures of all compounds were elucidated by spectroscopic analysis and comparing their NMR data with reported data. Furthermore, we found that compounds 6 and 9 had the antiangiogenic effects in vitro. They could inhibit HUVEC migration and microvessel sprouting in rat aortic rings. Moreover, compound 6 inhibited VEGFR and phosphorylation of Akt, but compound 9 only shown inhibitory effect on phosphorylation of Akt. Taken together, these results suggest that inhibition of VEGF signaling and downstream pathways may be responsible for the antiangiogenic activity of compounds 6 and 9.

5.
BMJ ; 368: l6744, 2020 01 06.
Artigo em Inglês | MEDLINE | ID: mdl-31907166

RESUMO

OBJECTIVE: To determine, in critically ill patients, the relative impact of proton pump inhibitors (PPIs), histamine-2 receptor antagonists (H2RAs), sucralfate, or no gastrointestinal bleeding prophylaxis (or stress ulcer prophylaxis) on outcomes important to patients. DESIGN: Systematic review and network meta-analysis. DATA SOURCES: Medline, PubMed, Embase, Cochrane Central Register of Controlled Trials, trial registers, and grey literature up to March 2019. ELIGIBILITY CRITERIA FOR SELECTING STUDIES AND METHODS: We included randomised controlled trials that compared gastrointestinal bleeding prophylaxis with PPIs, H2RAs, or sucralfate versus one another or placebo or no prophylaxis in adult critically ill patients. Two reviewers independently screened studies for eligibility, extracted data, and assessed risk of bias. A parallel guideline committee (BMJ Rapid Recommendation) provided critical oversight of the systematic review, including identifying outcomes important to patients. We performed random-effects pairwise and network meta-analyses and used GRADE to assess certainty of evidence for each outcome. When results differed between low risk and high risk of bias studies, we used the former as best estimates. RESULTS: Seventy two trials including 12 660 patients proved eligible. For patients at highest risk (>8%) or high risk (4-8%) of bleeding, both PPIs and H2RAs probably reduce clinically important gastrointestinal bleeding compared with placebo or no prophylaxis (odds ratio for PPIs 0.61 (95% confidence interval 0.42 to 0.89), 3.3% fewer for highest risk and 2.3% fewer for high risk patients, moderate certainty; odds ratio for H2RAs 0.46 (0.27 to 0.79), 4.6% fewer for highest risk and 3.1% fewer for high risk patients, moderate certainty). Both may increase the risk of pneumonia compared with no prophylaxis (odds ratio for PPIs 1.39 (0.98 to 2.10), 5.0% more, low certainty; odds ratio for H2RAs 1.26 (0.89 to 1.85), 3.4% more, low certainty). It is likely that neither affect mortality (PPIs 1.06 (0.90 to 1.28), 1.3% more, moderate certainty; H2RAs 0.96 (0.79 to 1.19), 0.9% fewer, moderate certainty). Otherwise, results provided no support for any affect on mortality, Clostridium difficile infection, length of intensive care stay, length of hospital stay, or duration of mechanical ventilation (varying certainty of evidence). CONCLUSIONS: For higher risk critically ill patients, PPIs and H2RAs likely result in important reductions in gastrointestinal bleeding compared with no prophylaxis; for patients at low risk, the reduction in bleeding may be unimportant. Both PPIs and H2RAs may result in important increases in pneumonia. Variable quality evidence suggested no important effects of interventions on mortality or other in-hospital morbidity outcomes. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42019126656.


Assuntos
Estado Terminal/terapia , Hemorragia Gastrointestinal , Antagonistas dos Receptores Histamínicos H2/farmacologia , Inibidores da Bomba de Prótons/farmacologia , Hemorragia Gastrointestinal/etiologia , Hemorragia Gastrointestinal/prevenção & controle , Humanos , Seleção de Pacientes , Risco Ajustado/métodos
6.
Int J Clin Pharm ; 2020 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-31919733

RESUMO

Background Over the last few years, pharmacists in China have been searching for effective strategies to expand their roles in pharmaceutical care. In September 2012, the Beijing Chaoyang Hospital was the first in China to establish the Chief-Pharmacist System aimed to let pharmacists be a responsible part of the multi-disciplinary care team. Objective To describe the Chief-Pharmacist System and explore its impact on drug expenditures and rational drug use. Setting A tertiary hospital in Beijing, China. Method Chief-Pharmacist System oriented specific measures were implemented and evaluated. Data on medical services quantity, quality and drug expenses during the periods of pre-implementation (from September 1, 2011 to August 31, 2012) and post implementation (from September 1, 2012 to August 31, 2016) were collected. Main outcome measure Healthcare quality indicators, drug expenditures, selected drug use indicators of outpatient and antibiotic use. Results With the implementation of the Chief-Pharmacist System and the participation of pharmacists in pharmaceutical care, drug expenses were reduced significantly. The total drug expenses, outpatient drug expenses per visit and inpatient drug expenses per admission decreased by an average of US $34.3 million, US $8.9 and US $ 303.9, respectively, compared to the pre-implementation period. Meanwhile, selected drug use indicators in post-implementation period were significantly improved. All results were achieved without sacrificing clinical quality and quantity. Conclusion The study illustrates that the Chief-Pharmacist System achieves substantial reductions in drug expenditures and promotion of rational drug use. It provides a model for other hospitals in China and other low- and middle-income countries.

7.
J Cell Mol Med ; 24(1): 328-341, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31639278

RESUMO

Overexposure to manganese (Mn) is neurotoxic. Our previous research has demonstrated that the interaction of endoplasmic reticulum (ER) stress and autophagy participates in the early stage of Mn-mediated neurotoxicity in mouse. However, the mechanisms of ER stress signalling pathways in the initiation of autophagy remain confused. In the current study, we first validated that ER stress-mediated cell apoptosis is accompanied by autophagy in SH-SY5Y cells. Then, we found that inhibiting ER stress with 4-phenylbutyrate (4-PBA) decreased ER stress-related protein expression and reduced cell apoptosis, whereas blocking autophagy with 3-methyladenine (3-MA) increased cell apoptosis. These data indicate that protective autophagy was activated to alleviate ER stress-mediated apoptosis. Knockdown of the protein kinase RNA-like ER kinase (PERK) gene inhibited Mn-induced autophagy and weakened the interaction between ATF4 and the LC3 promoter. Our results reveal a novel molecular mechanism in which ER stress may regulate autophagy via the PERK/eIF2α/ATF4 signalling pathway. Additionally, Mn may activate protective autophagy to alleviate ER stress-mediated apoptosis via the PERK/eIF2α/ATF4 signalling pathway in SH-SY5Y cells.

8.
Ecotoxicology ; 29(1): 35-44, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31749037

RESUMO

Although esterase-mediated spinosad resistance has been proposed for several insects, the associated molecular mechanism remains poorly understood. In this study, we investigated the mechanism of esterase-based spinosad resistance in house flies using a susceptible strain (SSS) and a spinosad-resistant, near-isogenic line (N-SRS). Combined with the synergistic effect of DEF on spinosad in the N-SRS strain, decreased ali-esterase activity in the spinosad-resistant strain has implicated the involvement of mutant esterase in spinosad resistance in house flies. Examination of the carboxylesterase gene MdαE7 in the two strains revealed that four non-synonymous mutations (Trp251-Leu, Asp273-Glu, Ala365-Val, and Ile396-Val) may be associated with spinosad resistance in house flies. Single nucleotide polymorphism analysis further indicated a strong relationship between these four mutations and spinosad resistance. Moreover, quantitative real-time PCR revealed a female-linked MdαE7 expression pattern in the N-SRS strain, which may contribute to sex-differential spinosad resistance in house flies.

9.
Environ Toxicol ; 35(1): 55-65, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31497924

RESUMO

Overexposure to manganese (Mn) is widely known to induce alpha-synuclein (α-Syn) oligomerization, which has been attributed to the oxidative damage of α-Syn protein. Trehalose has been shown to induce autophagy and serve as a chemical chaperone, but little information has been reported about its effect on Mn-induced α-Syn oligomerization. In this study, we investigate whether trehalose can effectively interfere with Mn-induced α-Syn oligomerization, using different concentrations of trehalose (2% and 4% (g/vol [mL])) in a mouse model of manganism. After 6 weeks of exposure to Mn, both oxidative stress and autophagy were activated and resulted in α-Syn oligomerization and neuronal cell damage in the mouse brain tissue. Our results also revealed that pretreatment with trehalose significantly reduced the oxidative damage to α-Syn protein and increased autophagy activation. These findings clearly demonstrated that trehalose can relieve Mn-induced α-Syn oligomerization and neuronal cell damage through its anti-oxidative and autophagy-inducing effects.


Assuntos
Autofagia/efeitos dos fármacos , Manganês/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Trealose/farmacologia , alfa-Sinucleína/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/ultraestrutura , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Chaperonas Moleculares/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/ultraestrutura , Multimerização Proteica
10.
Sci Total Environ ; 698: 134294, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31783459

RESUMO

Exposure to excess levels of manganese (Mn) may lead to nitrosative stress and neurotoxic effects on the central nervous system (CNS). The dysfunction of autophagy correlates with Mn-induced nitrosative stress; however, the exact mechanism of Mn-mediated autophagy dysfunction is still unclear. Three S-nitrosylated target proteins, namely, JNK, Bcl-2, and IKKß, were classified as the pivotal signaling pathway mediators that could play a role in the regulation of autophagy. To reveal whether these three proteins were involved in Mn-mediated autophagy dysregulation, we studied the effects of Mn on C57/BL6 mice and human neuroblastoma cells. Exposing the mice or cells, to 300 µmol/kg or 200 µM Mn, inhibited the degradation system of the autophagy-lysosome pathway. Additionally, in Mn-treated mice or cells, S-nitrosylated JNK, Bcl-2, and IKKß increased while the level of their phosphorylation reduced. The interaction of Beclin1 and Bcl-2 significantly increased in response to 200 µM Mn, whereas the decrease in phosphorylation of AMPK activated the mTOR pathway. We then used 20 µM 1400 W, an iNOS-specific inhibitor, to neutralize the nitrosative stress induced by Mn. Our results show that 1400 W reduced the S-nitrosylated JNK, Bcl-2, and Ikkß and relieved their downstream signaling molecular functions. Moreover, pretreatment with 20 µM 1400 W alleviated Mn-induced autophagic dysregulation and nerve cell injury. These findings revealed that S-nitrosylated JNK, Bcl-2, and IKKß are crucial signaling molecules in the Mn-mediated autophagic dysfunction.


Assuntos
Autofagia , Manganês/toxicidade , Animais , Proteínas Relacionadas à Autofagia , Humanos , Camundongos , Óxido Nítrico Sintase Tipo II , Proteínas Proto-Oncogênicas c-bcl-2 , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR , Testes de Toxicidade
11.
PLoS One ; 14(10): e0224094, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31648246

RESUMO

Francisella tularensis is a Gram-negative bacterium responsible for causing tularemia in the northern hemisphere. F. tularensis has long been developed as a biological weapon due to its ability to cause severe illness upon inhalation of as few as ten organisms and, based on its potential to be used as a bioterror agent is now classified as a Tier 1 Category A select agent by the CDC. The stringent response facilitates bacterial survival under nutritionally challenging starvation conditions. The hallmark of stringent response is the accumulation of the effector molecules ppGpp and (p)ppGpp known as stress alarmones. The relA and spoT gene products generate alarmones in several Gram-negative bacterial pathogens. RelA is a ribosome-associated ppGpp synthetase that gets activated under amino acid starvation conditions whereas, SpoT is a bifunctional enzyme with both ppGpp synthetase and ppGpp hydrolase activities. Francisella encodes a monofunctional RelA and a bifunctional SpoT enzyme. Previous studies have demonstrated that stringent response under nutritional stresses increases expression of virulence-associated genes encoded on Francisella Pathogenicity Island. This study investigated how stringent response governs the oxidative stress response of F. tularensis. We demonstrate that RelA/SpoT-mediated ppGpp production alters global gene transcriptional profile of F. tularensis in the presence of oxidative stress. The lack of stringent response in relA/spoT gene deletion mutants of F. tularensis makes bacteria more susceptible to oxidants, attenuates survival in macrophages, and virulence in mice. This work is an important step forward towards understanding the complex regulatory network underlying the oxidative stress response of F. tularensis.

12.
Basic Clin Pharmacol Toxicol ; 125(6): 536-547, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31483928

RESUMO

Chronic overexposure to manganese (Mn) has been verified to induce mitochondrial dysfunction, which is related to oxidative damage. The autophagic-lysosomal degradation pathway plays a vital role in the removal of impaired mitochondria through a specific quality control mechanism termed mitophagy. However, trehalose functions as an inducer of autophagy by an mTOR-independent mechanism, and little data report its effect on Mn-induced mitochondrial dysfunction. To explore the possibility that trehalose could be effective in interfering with the Mn-induced mitochondrial dysfunction, we used trehalose (2% and 4% (g/vol (mL))) in a mouse model of manganism. Our data showed that mice developed weary motor and behavioural deficits after exposure to Mn for 6 weeks. Overexposure to Mn resulted in mitochondrial dysfunction and neuronal cell damage in the basal nuclei of mice, which could be ameliorated by trehalose pre-treatment. Moreover, our results indicated that trehalose pre-treatment significantly reduced the oxidative damage and enhanced the activation of mitophagy. The findings clearly demonstrated that trehalose could relieve Mn-induced mitochondrial and neuronal cell damage through its antioxidative and mitophagy-inducing effects.

13.
Front Chem ; 7: 506, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31380350

RESUMO

As a typical 2D carbon material, graphene, that possesses outstanding physical/chemical properties, has revealed great potential for developing soft actuators. Especially, the unique properties of graphene, including the excellent light absorption property, softness, and thermal conductivity, play very important roles in the development of light-responsive graphene actuators. At present, various light-driven actuators have been successfully developed based on graphene and its derivatives. In this mini review, we reviewed the recent advances in this field. The unique properties of graphene or graphene-related materials that are of benefit to the development of light-driven actuators have been summarized. Typical smart actuators based on different photothermal/photochemical effects, including photothermal expansion, photothermal desorption, photoisomerization, and photo-triggered shape memory effect, have been introduced. Besides, current challenges, and future perspective have been discussed. The rapid progress of light-responsive actuators based on graphene has greatly stimulated the development of graphene-based soft robotics.

14.
ChemSusChem ; 12(16): 3792-3800, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31228339

RESUMO

Searching for low-cost, high-efficiency, bifunctional, non-noble-metal electrocatalysts for overall water splitting is crucial to renewable energy conversion. Herein, a series of component-controllable CC/CNTs@CoSx Se2(1-x) (CC: carbon cloth, CNT: carbon nanotube) with excellent bifunctional properties in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were obtained by chemical vapor deposition. In this strategy, the Zif-67 precursor served as a structural inducer, which was directly grown on CC and pyrolyzed with the assistance of melamine to form multi-walled CNT-encapsulated CoSx Se2(1-x) hierarchical nanostructures. Subsequently, the electrocatalytic properties of the as-prepared materials were optimized by adjusting the S/Se molar ratio. Of note is that the lattice distortion caused by the different radii of Se and S generated a polarized electric field for easy adsorption of the intermediate products. The CoOOH generated in situ on the surface of CoSx Se2(1-x) , as well as n- and p-type domains in carbon, synergistically resulted in abundant active sites to boost the electrocatalytic activity. CC/CNTs@CoS0.74 Se0.52 exhibited overpotentials for the HER and OER of 225 and 285 mV, respectively and attained a current density of 10 mA cm-2 in alkaline solution. The as-prepared electrocatalysts could act as both cathode and anode in a water electrolyzer showing a cell voltage of 1.74 V and delivering 10 mA cm-2 , comparable to those of noble-metal-based water electrolyzers.

15.
Medicine (Baltimore) ; 98(25): e16078, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31232948

RESUMO

RATIONALE: Toxic epidermal necrolysis (TEN) is a life-threatening, immunologically mediated, and usually drug-induced disease. Rarely, clinical pharmacists participating in finding the etiology have been reported. PATIENTS CONCERNS: A 33-year-old male presented to the emergency department with a 1-day history of fever and rash. The patient, being newly diagnosed with gout 10 days ago, received allopurinol at a dose of 250 mg by mouth daily. After 10 days' exposure to allopurinol, the patient manifested with an "influenza-like" prodromal phase (fever of 38°C, throat pains), which was treated with amoxicillin and nonsteroidal anti-inflammatory drugs of the oxicam type. The next day, he developed a worsening fever of 39.5°C, accompanied by a pruriginous rash all over his body. DIAGNOSIS: On physical examination, we observed coalescing dusky red macules over >60% of his body surface area, with blisters and detachment of large sheets of necrolytic epidermis all over his chest and face. The diagnosis of TEN was confirmed. INTERVENTIONS: The patient recovered following treatment with short-term high-dose methylprednisolone sodium succinate, immunoglobulin therapy, topical medication, and supportive therapy. OUTCOMES: He showed a slow but progressive improvement both in symptoms and cutaneous manifestations. Reepithelization of the skin was achieved after 3 weeks. LESSONS: Drug-induced-TEN is potentially fatal. This case underlines the necessity of asking medication history in detail and detecting related drug gene to correctly identify the cause of TEN.


Assuntos
Alopurinol/toxicidade , Síndrome de Stevens-Johnson/etiologia , Adulto , Alopurinol/uso terapêutico , Serviço Hospitalar de Emergência/organização & administração , Supressores da Gota/uso terapêutico , Supressores da Gota/toxicidade , Humanos , Masculino
16.
Pestic Biochem Physiol ; 157: 178-185, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31153466

RESUMO

Females developed notably higher resistance than males in a spinosad-resistant house fly strain, however, resistance factors responsible for this phenomenon are poorly understood. In this study, the potential role of cytochrome P450 monooxygenases involved in the sex-differential spinosad resistance in house flies was investigated, using a susceptible strain (SSS) and a spinosad resistant near-isogenic line (N-SRS). Combination of the synergism of spinosad by PBO and increased cytochrome P450 monooxygenase activity in the N-SRS strain implied that cytochrome P450 monooxygenases contributed to spinosad resistance in house flies. Transcriptional levels of eight P450 genes related to insecticide resistance in two genders of the SSS and N-SRS strain were separately evaluated by quantitative real-time PCR. Notably, compared with the corresponding gender of susceptible SSS house flies, CYP4G2 and CYP6A5v2 were overexpressed in resistant N-SRS females, while the expression of these two P450 genes was significantly decreased in resistant N-SRS males. Furthermore, by measuring the expression of CYP4G2 and CYP6A5v2 in female and male house fly populations with different spinosad resistance levels, which were generated from a series of genetic crosses, the genetic linkage between spinosad resistance and P450 gene expression was analyzed. It was found that with increased spinosad resistance, CYP4G2 and CYP6A5v2 were up-regulated in females, while both of them were down-regulated in males, and this suggested their involvement in the female-linked spinosad resistance of house flies. Taken together, our results provide valuable insight into the involvement of cytochrome P450 monooxygenases in the sex-differential spinosad resistance in house flies.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Moscas Domésticas/efeitos dos fármacos , Macrolídeos/farmacologia , Muscidae/efeitos dos fármacos , Animais , Sistema Enzimático do Citocromo P-450/genética , Combinação de Medicamentos , Feminino , Resistência a Inseticidas/genética , Masculino
17.
PLoS One ; 14(3): e0213699, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30870480

RESUMO

Francisella tularensis is a Gram-negative, facultative intracellular pathogen and the causative agent of a lethal human disease known as tularemia. Due to its extremely high virulence and potential to be used as a bioterror agent, F. tularensis is classified by the CDC as a Category A Select Agent. As an intracellular pathogen, F. tularensis during its intracellular residence encounters a number of oxidative and nitrosative stresses. The roles of the primary antioxidant enzymes SodB, SodC and KatG in oxidative stress resistance and virulence of F. tularensis live vaccine strain (LVS) have been characterized in previous studies. However, very fragmentary information is available regarding the role of peroxiredoxin of the AhpC/TSA family (annotated as AhpC) of F. tularensis SchuS4; whereas the role of AhpC of F. tularensis LVS in tularemia pathogenesis is not known. This study was undertaken to exhaustively investigate the role of AhpC in oxidative stress resistance of F. tularensis LVS and SchuS4. We report that AhpC of F. tularensis LVS confers resistance against a wide range of reactive oxygen and nitrogen species, and serves as a virulence factor. In highly virulent F. tularensis SchuS4 strain, AhpC serves as a key antioxidant enzyme and contributes to its robust oxidative and nitrosative stress resistance, and intramacrophage survival. We also demonstrate that there is functional redundancy among primary antioxidant enzymes AhpC, SodC, and KatG of F. tularensis SchuS4. Collectively, this study highlights the differences in antioxidant defense mechanisms of F. tularensis LVS and SchuS4.


Assuntos
Antioxidantes/fisiologia , Francisella tularensis/enzimologia , Estresse Oxidativo , Peroxirredoxinas/fisiologia , Tularemia/microbiologia , Animais , Proteínas de Bactérias/fisiologia , Vacinas Bacterianas/imunologia , Francisella tularensis/patogenicidade , Teste de Complementação Genética , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Células RAW 264.7 , Superóxido Dismutase/fisiologia , Tularemia/imunologia , Vacinas Atenuadas/imunologia , Virulência
18.
Front Microbiol ; 10: 345, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30891010

RESUMO

The extensive use of daptomycin for treating complex methicillin-resistant Staphylococcus aureus infections has led to the emergence of daptomycin-resistant strains. Although genomic studies have identified mutations associated with daptomycin resistance, they have not necessarily provided insight into the evolution and hierarchy of genetic changes that confer resistance, particularly as antibiotic concentrations are increased. Additionally, plate-dependent in vitro analyses that passage bacteria in the presence of antibiotics can induce selective pressures unrelated to antibiotic exposure. We established a continuous culture bioreactor model that exposes S. aureus strain N315 to increasing concentrations of daptomycin without the confounding effects of nutritional depletion to further understand the evolution of drug resistance and validate the bioreactor as a method that produces clinically relevant results. Samples were collected every 24 h for a period of 14 days and minimum inhibitory concentrations were determined to monitor the acquisition of daptomycin resistance. The collected samples were then subjected to whole genome sequencing. The development of daptomycin resistance in N315 was associated with previously identified mutations in genes coding for proteins that alter cell membrane charge and composition. Although genes involved in metabolic functions were also targets of mutation, the common route to resistance relied on a combination of mutations at a few key loci. Tracking the frequency of each mutation throughout the experiment revealed that mutations need not arise progressively in response to increasing antibiotic concentrations and that most mutations were present at low levels within populations earlier than would be recorded based on single-nucleotide polymorphism (SNP) filtering criteria. In contrast, a serial-passaged population showed only one mutation in a gene associated with resistance and provided limited detail on the changes that occur upon exposure to higher drug dosages. To conclude, this study demonstrates the successful in vitro modeling of antibiotic resistance in a bioreactor and highlights the evolutionary paths associated with the acquisition of daptomycin non-susceptibility.

19.
Cell Res ; 29(4): 305-312, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30814678

RESUMO

The type III CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated genes) systems are bacterially encoded adaptive immune systems for defense against invading nucleic acids. They accomplish this task through the coordinated cleavage of invading substrates of single-stranded RNA and DNA (ssDNA and ssRNA) by the Csm (type III-A) or Cmr (type III-B) effector complexes. The ssRNA is complementarily bound to the CRISPR RNA (crRNA). However, the structural basis for the DNase and RNase activation of the Csm nucleoprotein complex is largely unknown. Here we report cryo-EM structures of the Csm-crRNA complex, with or without target ssRNA, at near-atomic resolution. Our cryo-EM maps allow us to build atomic models of the key macromolecular components, including Cas10, Csm2, Csm3, Csm4, crRNA and the invading ssRNA. Our structure resolves unambiguously the stoichiometry and tertiary structures of the Csm protein complex and the interactions between protein components and the crRNA/ssRNA. Interestingly, the new atomic structures of the Csm proteins presented here are similar to those of previously known Csm proteins in other species despite their low sequence similarity. Our combined structural and biochemical data suggest that ssRNA cleavage is preferentially carried out near its 5'-end, that the extent of interactions among the ssRNA, crRNA and the protein components regulates the DNase activity of the Csm complex, and that the 3' flanking sequence of ssRNA activates the Cas10 DNase activity allosterically.

20.
Medicine (Baltimore) ; 98(10): e14789, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30855492

RESUMO

RATIONALE: Thymoma is a type of rare tumor in the thymus gland, and among patients with thymoma, less than 10% will develop pure red cell aplasia (PRCA), whereas less than 5% of patients with PRCA have a thymoma. The optimal approach for PRCA in thymoma is immunosuppressive therapy, such as steroids, cyclosporine, and human antithymocyte globulin. PATIENT CONCERNS: A sixty-one-year-old male was diagnosed with thymoma with PRCA after he complained fatigue, tinnitus, and weakness for 1 month, he received therapy with recombinant erythropoietin (rhEPO) for 1 month after the tumor was totally resected and readmitted with pulmonary embolism and received anticoagulation therapy with enoxaparin for 3 months. DIAGNOSES: Thymoma, pure red cell aplasia, pulmonary embolism. INTERVENTION: He received cyclosporine A, prednisone and rhEPO treatment. Two months after the thymectomy and postoperative radiation, he was readmitted with pulmonary embolism. OUTCOMES: Thymoma and pulmonary embolism become complete response (CR), PRCA become partial response (PR). LESSONS: Clinicians should be alert to the possibility of the increased risk of thrombosis induced by rhEPO when it used to treat PRCA associated with thymoma. If other medication is effective for managing PRCA, rhEPO should be avoided.


Assuntos
Eritropoetina/efeitos adversos , Fármacos Hematológicos/efeitos adversos , Embolia Pulmonar/etiologia , Aplasia Pura de Série Vermelha/tratamento farmacológico , Timoma/complicações , Neoplasias do Timo/complicações , Eritropoetina/uso terapêutico , Fármacos Hematológicos/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Embolia Pulmonar/diagnóstico por imagem , Embolia Pulmonar/patologia , Embolia Pulmonar/terapia , Proteínas Recombinantes/efeitos adversos , Proteínas Recombinantes/uso terapêutico , Timoma/terapia , Neoplasias do Timo/terapia
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