scholarly journals Pneumocystis Melanins Confer Enhanced Organism Viability

2006 ◽  
Vol 5 (6) ◽  
pp. 916-923 ◽  
Author(s):  
Crystal R. Icenhour ◽  
Theodore J. Kottom ◽  
Andrew H. Limper
Keyword(s):  
Fungal Pathogen ◽  
Pneumocystis Carinii ◽  
Environmental Stressors ◽  
Resonance Spectroscopy ◽  
Reverse Transcription Pcr ◽  
Spin Resonance ◽  
Opportunistic Fungal Pathogen ◽  
Adverse Environmental Conditions ◽  
Previous Identification

ABSTRACT Pneumocystis continues to represent an important opportunistic fungal pathogen of those with compromised immunity. Thus, it is crucial to identify factors that affect its viability and pathogenicity. We previously reported the first identification of melanins in Pneumocystis. In the present study, we sought to further characterize these components and define the function for these melanins. Melanins extracted from Pneumocystis and melanized Pneumocystis cells were analyzed by electron spin resonance spectroscopy, revealing spectra consistent with melanins from other fungi. Immunofluorescence assays using anti-melanin monoclonal antibodies showed that melanins are widely present across Pneumocystis host species, including mouse-, ferret-, and human-derived Pneumocystis organisms, as well as Pneumocystis carinii derived from rat. Using immunoelectron microscopy, melanins were found to localize to the cell wall and cytoplasm of P. carinii cysts, as well as to intracystic bodies within mature cysts. Next, the role of melanins on the maintenance of Pneumocystis viability was determined by using quantitative reverse transcription-PCR measurement of the heat shock protein mRNA under adverse environmental conditions. Using a new method to promote the melanization of Pneumocystis, we observed that strongly melanized Pneumocystis retained viability to a greater degree when exposed to UV irradiation or desiccation compared to less-pigmented organisms. These studies support our previous identification of Pneumocystis melanins across the genus, further characterize these Pneumocystis components, and demonstrate that melanins protect Pneumocystis from environmental stressors.

scholarly journals Complement and Fc Function Are Required for Optimal Antibody Prophylaxis against Pneumocystis carinii Pneumonia

2006 ◽  
Vol 74 (1) ◽  
pp. 390-393 ◽  
Author(s):  
Jesse Wells ◽  
Constantine G. Haidaris ◽  
Terry W. Wright ◽  
Francis Gigliotti
Keyword(s):  
Monoclonal Antibody ◽  
Fungal Pathogen ◽  
Complement Fixation ◽  
Pneumocystis Carinii ◽  
Immunocompromised Host ◽  
Scid Mice ◽  
Maximum Effect ◽  
Opportunistic Fungal Pathogen ◽  
Optimal Effect

ABSTRACT Pneumocystis carinii is an opportunistic fungal pathogen that causes P. carinii pneumonia (PCP) in the immunocompromised host. We investigated the role of antibody Fc-mediated function in passive prophylaxis against the development of PCP in SCID mice. By comparison of anti-mouse P. carinii immunoglobulin G1 monoclonal antibody (MAb) 4F11(G1) and its F(ab′)2 derivative in an intranasal immunoprophylaxis model, we determined that Fc-mediated function is required for maximum effect of this antibody. Comparison of efficacy of antibody prophylaxis in SCID mice depleted of complement to that in nondepleted mice demonstrated that complement fixation by MAb 4F11(G1) is also necessary for optimal effect of passively administered antibody, although residual protection was observed in complement-depleted SCID mice. The necessity of complement for optimal PCP prophylaxis by MAb 4F11(G1) suggests that complement may play a role in antibody-mediated protection against development of PCP.

scholarly journals Environmentally persistent free radicals are ubiquitous in wildfire charcoals and remain stable for years

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Gabriel Sigmund ◽  
Cristina Santín ◽  
Marc Pignitter ◽  
Nathalie Tepe ◽  
Stefan H. Doerr ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Free Radicals ◽  
Reactive Oxygen ◽  
Resonance Spectroscopy ◽  
Oxygen Species ◽  
Pyrogenic Carbon ◽  
Spin Resonance ◽  
Long Time ◽  
High Concentrations

AbstractGlobally landscape fires produce about 256 Tg of pyrogenic carbon or charcoal each year. The role of charcoal as a source of environmentally persistent free radicals, which are precursors of potentially harmful reactive oxygen species, is poorly constrained. Here, we analyse 60 charcoal samples collected from 10 wildfires, that include crown as well as surface fires in forest, shrubland and grassland spanning different boreal, temperate, subtropical and tropical climate. Using electron spin resonance spectroscopy, we measure high concentrations of environmentally persistent free radicals in charcoal samples, much higher than those found in soils. Concentrations increased with degree of carbonization and woody fuels favoured higher concentrations. Moreover, environmentally persistent free radicals remained stable for an unexpectedly long time of at least 5 years. We suggest that wildfire charcoal is an important global source of environmentally persistent free radicals, and therefore potentially of harmful reactive oxygen species.

scholarly journals Multifactorial Role of Mitochondria in Echinocandin Tolerance Revealed by Transcriptome Analysis of Drug-Tolerant Cells

mBio ◽  
2021 ◽  
Author(s):  
Rocio Garcia-Rubio ◽  
Cristina Jimenez-Ortigosa ◽  
Lucius DeGregorio ◽  
Christopher Quinteros ◽  
Erika Shor ◽  
...  
Keyword(s):  
Fungal Pathogen ◽  
Candida Glabrata ◽  
Clinical Failure ◽  
First Line ◽  
Content Type ◽  
First Line Therapy ◽  
Line Therapy ◽  
Resistant Strains ◽  
Opportunistic Fungal Pathogen

Echinocandin drugs are a first-line therapy to treat invasive candidiasis, which is a major source of morbidity and mortality worldwide. The opportunistic fungal pathogen Candida glabrata is a prominent bloodstream fungal pathogen, and it is notable for rapidly developing echinocandin-resistant strains associated with clinical failure.

scholarly journals Characterization of the Pneumocystis carinii Histone Acetyltransferase Chaperone Proteins PcAsf1 and PcVps75

2013 ◽  
Vol 81 (6) ◽  
pp. 2268-2275 ◽  
Author(s):  
Jakrapun Pupaibool ◽  
Theodore J. Kottom ◽  
Kelly Bouchonville ◽  
Andrew H. Limper
Keyword(s):  
Dna Replication ◽  
Cell Cycle Progression ◽  
Pneumocystis Carinii ◽  
Histone H3 ◽  
Content Type ◽  
Dna Replication And Repair ◽  
Opportunistic Fungal Pathogen ◽  
Vacuolar Protein

ABSTRACTRtt109 is a lysine acetyltransferase that acetylates histone H3 at lysine 56 (H3K56) in fungi. This acetylation event is important for proper DNA replication and repair to occur. Efficient Rtt109 acetyltransferase activity also requires a histone chaperone, vacuolar protein sorting 75 (Vps75), as well as the major chaperone of the H3-H4 dimer, anti-silencing factor 1 (Asf1). Little is known about the role of these proteins in the opportunistic fungal pathogenPneumocystis carinii. To investigate the functions of Asf1 and Vps75 inPneumocystis carinii, we cloned and characterized both of these genes. Here, we demonstrate that both genes,P. carinii asf1(Pcasf1) andPcvps75, function in a fashion analogous to theirSaccharomyces cerevisiaecounterparts. We demonstrate that bothP. cariniiAsf1 (PcAsf1) and PcVps75 can bind histones. Furthermore, whenPcasf1is expressed heterologously inS. cerevisiae asf1Δ cells, PcAsf1 can restore full H3 lysine acetylation. We further demonstrated that thePcasf1cDNA expressed inasf1ΔS. cerevisiaecells can restore growth to wild-type levels in the presence of genotoxic agents that block DNA replication. Lastly, we observed that purified PcAsf1 and PcVps75 proteins enhance the ability of PcRtt109 to acetylate histone H3-H4 tetramers. Together, our results indicate that the functions of the Rtt109-Asf1-Vps75 complex in the acetylation of histone H3 lysine 56 and in DNA damage response are present inP. cariniiDNA and cell cycle progression.

The Presence and Role of Paramagnetic Impurities in the Degradation of Paper

1996 ◽  
Vol 462 ◽  
Author(s):  
Donato Attanasio ◽  
Donatella Capitani ◽  
Maria C. Emanuele
Keyword(s):  
Electron Spin Resonance ◽  
Point Defects ◽  
Systematic Investigation ◽  
Electron Spin Resonance Spectroscopy ◽  
Resonance Spectroscopy ◽  
Paramagnetic Impurities ◽  
Quantitative Monitoring ◽  
Spin Resonance ◽  
Paramagnetic Centres

ABSTRACTElectron Spin Resonance spectroscopy has been used to carry out a systematic investigation of the paramagnetic impurities present in antique and modern paper. Up to eleven different paramagnetic centres, which include different transition ions (Fe3+, Mn2+, Cu2+), organic free radicals, and paramagnetic point defects have been detected, in concentrations ranging from few ppm to several hundreds. Experiments performed on new and deteriorated samples strongly indicate that some of these impurities participate directly or are produced during the aging and degradation processes. They can be used as quality indicators or probes for quantitative monitoring of the degradation of paper.

scholarly journals Pneumocystis carinii Interactions with Lung Epithelial Cells and Matrix Proteins Induce Expression and Activity of the PcSte20 Kinase with Subsequent Phosphorylation of the Downstream Cell Wall Biosynthesis Kinase PcCbk1

2011 ◽  
Vol 79 (10) ◽  
pp. 4157-4164 ◽  
Author(s):  
Theodore J. Kottom ◽  
Joshua W. Burgess ◽  
Andrew H. Limper
Keyword(s):  
Cell Wall ◽  
Epithelial Cells ◽  
Fungal Pathogen ◽  
Pneumocystis Carinii ◽  
Specific Region ◽  
Lung Epithelial Cells ◽  
Matrix Proteins ◽  
Content Type ◽  
Lung Epithelial ◽  
Opportunistic Fungal Pathogen

ABSTRACTEukaryotic cell proliferation and phenotype are highly regulated by contact-dependent mechanisms. We have previously shown that the binding and interaction of the opportunistic fungal pathogenPneumocystis cariniito lung epithelial cells and extracellular matrix proteins induces mRNA expression of both the mitogen-activated protein (MAP) kinaseP. cariniiSte20 (PcSte20) and the cell wall-remodeling enzymePcCbk1(16). Herein, we report that in addition toPcSte20mRNA expression being upregulated,PneumocystisPcSte20 kinase activity is increased upon interacting with these same lung targets. This activity is also significantly suppressed byClostridium difficiletoxin B, a pan-specific inhibitor of small GTPases, demonstrating the potential role of a Cdc42-like molecule in this signaling cascade. We further observed that the PcSte20 kinase physically interacts with a specific region of theP. cariniicell wall biosynthesis kinase, PcCbk1, a downstream kinase important for mating projection formation and cell wall remodeling. This direct binding was mapped to a specific region of the PcCbk1 protein. We also demonstrated that PcSte20 obtained from wholeP. cariniilysates has the ability to phosphorylate PcCbk1 after the organism interacts with lung epithelial cells and extracellular matrix components. These observations provide new insights intoP. cariniisignaling induced by interactions of this important opportunistic fungal pathogen with lung epithelial cells and matrix.

scholarly journals Development of mesh-type Fenton-like Cu/Fex/γ-Al2O3/Al catalysts and application for catalytic degradation of dyes

2020 ◽  
Vol 81 (10) ◽  
pp. 2057-2065
Author(s):  
Huang Qian ◽  
Shao Qianwen ◽  
Zhang Qi ◽  
Ni Yanhui ◽  
Wu Yongqiang
Keyword(s):  
Degradation Rate ◽  
Bimetallic Catalyst ◽  
Radical Scavenging ◽  
Resonance Spectroscopy ◽  
Degradation Of Dyes ◽  
Spin Resonance ◽  
Temperature Programmed ◽  
Reactive Oxidant ◽  
Redox Ability

Abstract The application of nanoparticle heterogeneous Fenton-like catalysts is limited due to the requirement of filtration after reaction and possible secondary pollution. In this work, a novel mesh-type monolithic Fenton-like Cu/Fex/γ-Al2O3/Al catalyst was developed for the degradation of dyes. The Cu and Fe species are uniformly dispersed on the mesh-type anodic monolithic γ-Al2O3 supports, and the results of scanning electron microscopy and X-ray diffractometry analysis show that Fe can reduce the particle size of Cu over γ-Al2O3. The activity results show that the degradation rate of rhodamine B (RhB) reached 99.5% within 1 h using 4 × 6 cm Cu12.0/Fe2.0/γ-Al2O3/Al catalyst with 1,200 ppm H2O2 at 50 °C. The important role of •OH as a reactive oxidant was confirmed through electron spin-resonance spectroscopy and radical scavenging experiment. The hydrogen temperature programmed reduction suggests the high redox ability of Cu/Fe bimetallic catalyst is beneficial to the production of •OH. The Cu/Fe bimetallic catalyst shows excellent recyclability in a 10-cycle experiment, the degradation rate of RhB was maintained at 98% and the leaching amount of metals was lower than 0.7 mg/L. The mesh-type catalyst will be easily applied for the continuous wastewater treatment because it does not need filtration for recovery.

Defect Creation and Photoablation in Stoichiometric and Sub-Stoichiometric SiO2

1985 ◽  
Vol 60 ◽  
Author(s):  
R. A. B. Devine ◽  
C. Fiori
Keyword(s):  
Point Defects ◽  
Defect Structure ◽  
Measurement Techniques ◽  
Electrical Measurement ◽  
Resonance Spectroscopy ◽  
Physical Mechanisms ◽  
Spin Resonance ◽  
Different Types ◽  
Comparison Of The Results

AbstractIt is demonstrated that microscopic point defects can be created in amorphous silica using pulsed ultraviolet irradiation (λ = 248 nm) at energy densities ∼ 100 times less than those normally estimated to lead to damage creation. Identification of the physical character of the defects has been made using electron spin resonance spectroscopy and electrical measurement techniques. Continued irradiation of the SiO2 is found to lead to photoablation. Results obtained for bulk dry SiO2, thermal SiO2 and vacuum deposited SiOx are presented. The important role of non-stoichiometry (defect structure) in the process of photoablation is clearly manifested by comparison of the results obtained for the different types of SiO2. Possible physical mechanisms involved are discussed.

Effect of K2S2O8 on Material Removal Rate in Abrasive-Free Polishing of Hard Disk Substrate

2013 ◽  
Vol 690-693 ◽  
pp. 3222-3225 ◽  
Author(s):  
Rong Zhao ◽  
Hong Lei
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Hard Disk ◽  
Resonance Spectroscopy ◽  
Electrochemical Test ◽  
Spin Resonance ◽  
Hard Disk Substrate ◽  
Disk Substrate

The role of K2S2O8 (KPS) initiator on the material removal rate (MRR) of hard disk substrate in the H2O2-based slurry was investigated. Experiment results indicate that the MRR of slurry containing KPS and H2O2 is higher than that of slurry containing only H2O2 under the same testing conditions. The electrochemical test shows that KPS can increase the corrosion rate of hard disk substrate in the H2O2-based slurry. The electron spin-resonance spectroscopy (EPR) analysis shows that KPS, as an initiator, can increase the number of OH• free radical. Further, the reaction mechanism of KPS in abrasive-free polishing of hard disk substrate is discussed.

Pyrite-enhanced degradation of chloramphenicol by low concentrations of H2O2

2015 ◽  
Vol 72 (2) ◽  
pp. 180-186 ◽  
Author(s):  
Deli Wu ◽  
Yanxia Liu ◽  
Zhiyong Zhang ◽  
Luming Ma ◽  
Yalei Zhang
Keyword(s):  
Energy Dispersive Spectrometry ◽  
Gas Chromatography Mass Spectrometry ◽  
Resonance Spectroscopy ◽  
Low Concentrations ◽  
Spin Resonance ◽  
Initial Ph ◽  
Catalyzed Reactions ◽  
Natural Pyrite ◽  
Enhanced Degradation

A pyrite-catalyzed reaction was used to degrade chloramphenicol. Chloramphenicol could be almost 100% removed within 60 minutes when 1 mM H2O2 and 0.1 g/L pyrite were added at an initial pH = 3. During oxidation, intermediates such as nitrobenzaldehyde and dichloroacetamide were identified by gas chromatography/mass spectrometry (GC/MS). The •OH was identified by electron spin-resonance spectroscopy. Pyrite was digested to determine elements by ICP (inductive coupled plasma emission spectrometer). To understand the reaction mechanism and the role of natural pyrite in these processes, techniques including scanning electron microscopy and energy dispersive spectrometry were employed to characterize the solid sample. The results explain that pyrite acts as a ‘bond’ between Fe3+ and H2O2, and this pathway continues to form •OH and inhibit the quenching reaction. Therefore, pyrite-catalyzed reactions would proceed even in low concentrations of H2O2.

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