24 results on '"Rivera VA"'
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2. The Biosynthesis and Functions of Polyamines in the Interaction of Plant Growth-Promoting Rhizobacteria with Plants.
- Author
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Dunn MF and Becerra-Rivera VA
- Abstract
Plant growth-promoting rhizobacteria (PGPR) are members of the plant rhizomicrobiome that enhance plant growth and stress resistance by increasing nutrient availability to the plant, producing phytohormones or other secondary metabolites, stimulating plant defense responses against abiotic stresses and pathogens, or fixing nitrogen. The use of PGPR to increase crop yield with minimal environmental impact is a sustainable and readily applicable replacement for a portion of chemical fertilizer and pesticides required for the growth of high-yielding varieties. Increased plant health and productivity have long been gained by applying PGPR as commercial inoculants to crops, although with uneven results. The establishment of plant-PGPR relationships requires the exchange of chemical signals and nutrients between the partners, and polyamines (PAs) are an important class of compounds that act as physiological effectors and signal molecules in plant-microbe interactions. In this review, we focus on the role of PAs in interactions between PGPR and plants. We describe the basic ecology of PGPR and the production and function of PAs in them and the plants with which they interact. We examine the metabolism and the roles of PAs in PGPR and plants individually and during their interaction with one another. Lastly, we describe some directions for future research.
- Published
- 2023
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3. NOD2 Agonism Counter-Regulates Human Type 2 T Cell Functions in Peripheral Blood Mononuclear Cell Cultures: Implications for Atopic Dermatitis.
- Author
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Gimenez-Rivera VA, Patel H, Dupuy FP, Allakhverdi Z, Bouchard C, Madrenas J, Bissonnette R, Piccirillo CA, and Jack C
- Subjects
- Adult, Humans, Interleukin-13 metabolism, Leukocytes, Mononuclear metabolism, Staphylococcus aureus metabolism, Cytokines metabolism, Chemokines metabolism, Biomarkers, Nod2 Signaling Adaptor Protein metabolism, Dermatitis, Atopic drug therapy
- Abstract
Atopic dermatitis (AD) is known as a skin disease; however, T cell immunopathology found in blood is associated with its severity. Skin Staphylococcus aureus ( S. aureus ) and associated host-pathogen dynamics are important to chronic T helper 2 (Th2)-dominated inflammation in AD, yet they remain poorly understood. This study sought to investigate the effects of S. aureus -derived molecules and skin alarmins on human peripheral blood mononuclear cells, specifically testing Th2-type cells, cytokines, and chemokines known to be associated with AD. We first show that six significantly elevated Th2-related chemokine biomarkers distinguish blood from adult AD patients compared to healthy controls ex vivo; in addition, TARC/CCL17, LDH, and PDGF-AA/AB correlated significantly with disease severity. We then demonstrate that these robust AD-associated biomarkers, as well as associated type 2 T cell functions, are readily reproduced from healthy blood mononuclear cells exposed to the alarmin TSLP and the S. aureus superantigen SEB in a human in vitro model, including IL-13, IL-5, and TARC secretion as well as OX-40-expressing activated memory T cells. We further show that the agonism of nucleotide-binding oligomerization domain-containing protein (NOD)2 inhibits this IL-13 secretion and memory Th2 and Tc2 cell functional activation while inducing significantly increased pSTAT3 and IL-6, both critical for Th17 cell responses. These findings identify NOD2 as a potential regulator of type 2 immune responses in humans and highlight its role as an endogenous inhibitor of pathogenic IL-13 that may open avenues for its therapeutic targeting in AD.
- Published
- 2023
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4. The Sinorhizobium meliloti NspS-MbaA system affects biofilm formation, exopolysaccharide production and motility in response to specific polyamines.
- Author
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Chávez-Jacobo VM, Becerra-Rivera VA, Guerrero G, and Dunn MF
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, Biofilms, Gene Expression Regulation, Bacterial, Polysaccharides, Bacterial metabolism, Polyamines metabolism, Sinorhizobium meliloti genetics, Sinorhizobium meliloti metabolism
- Abstract
We previously showed that specific polyamines (PAs) present in the extracellular environment markedly affect extracellular polysaccharide (EPS) production, biofilm formation and motility in Sinorhizobium meliloti Rm8530. We hypothesized that extracellular PA signals were sensed and transduced by the NspS and MbaA proteins, respectively, which are homologs of the PA-sensing, c-di-GMP modulating NspS-MbaA proteins described in Vibrio cholerae . Here we show that the decrease in biofilm formation and EPS production in the quorum-sensing (QS)-deficient S. meliloti wild-type strain 1021 in cultures containing putrescine or spermine did not occur in a 1021 nspS mutant (1021 nspS). The transcriptional expression of nspS in strain 1021 was significantly increased in cultures containing either of these polyamines, but not by exogenous cadaverine, 1,3-diaminopropane (DAP), spermidine (Spd) or norspermidine (NSpd). Cell aggregation in liquid cultures did not differ markedly between strain 1021 and 1021 nspS in the presence or absence of PAs. The S. meliloti QS-proficient Rm8530 wild-type and nspS mutant (Rm8530 nspS) produced similar levels of biofilm under control conditions and 3.2- and 2.2-fold more biofilm, respectively, in cultures with NSpd, but these changes did not correlate with EPS production. Cells of Rm8530 nspS aggregated from two- to several-fold more than the wild-type in cultures without PAs or in those containing Spm. NSpd, Spd and DAP differently affected swimming and swarming motility in strains 1021 and Rm8530 and their respective nspS mutants. nspS transcription in strain Rm8530 was greatly reduced by exogenous Spm. Bioinformatic analysis revealed similar secondary structures and functional domains in the MbaA proteins of S. meliloti and V. cholerae , while their NspS proteins differed in some residues implicated in polyamine recognition in the latter species. NspS-MbaA homologs occur in a small subset of soil and aquatic bacterial species that commonly interact with eukaryotes. We speculate that the S. meliloti NspS-MbaA system modulates biofilm formation, EPS production and motility in response to environmental or host plant-produced PAs.
- Published
- 2023
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5. Skin Sodium Accumulates in Psoriasis and Reflects Disease Severity.
- Author
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Maifeld A, Wild J, Karlsen TV, Rakova N, Wistorf E, Linz P, Jung R, Birukov A, Gimenez-Rivera VA, Wilck N, Bartolomaeus T, Dechend R, Kleinewietfeld M, Forslund SK, Krause A, Kokolakis G, Philipp S, Clausen BE, Brand A, Waisman A, Kurschus FC, Wegner J, Schultheis M, Luft FC, Boschmann M, Kelm M, Wiig H, Kuehne T, Müller DN, Karbach S, and Markó L
- Subjects
- Animals, Cell Differentiation, Cells, Cultured, Humans, Lymphocyte Activation, Male, Mice, Mice, Inbred C57BL, Severity of Illness Index, Skin pathology, Sodium Chloride metabolism, Spectrophotometry, Atomic, Spectrum Analysis, Interleukin-17 metabolism, Psoriasis metabolism, Skin metabolism, Sodium analysis, Th17 Cells immunology
- Abstract
Sodium can accumulate in the skin at concentrations exceeding serum levels. A high sodium environment can lead to pathogenic T helper 17 cell expansion. Psoriasis is a chronic inflammatory skin disease in which IL-17‒producing T helper 17 cells play a crucial role. In an observational study, we measured skin sodium content in patients with psoriasis and in age-matched healthy controls by Sodium-23 magnetic resonance imaging. Patients with PASI > 5 showed significantly higher sodium and water content in the skin but not in other tissues than those with lower PASI or healthy controls. Skin sodium concentrations measured by Sodium-23 spectroscopy or by atomic absorption spectrometry in ashed-skin biopsies verified the findings with Sodium-23 magnetic resonance imaging. In vitro T helper 17 cell differentiation of naive CD4
+ cells from patients with psoriasis markedly induced IL-17A expression under increased sodium chloride concentrations. The imiquimod-induced psoriasis mouse model replicated the human findings. Extracellular tracer Chromium-51-EDTA measurements in imiquimod- and sham-treated skin showed similar extracellular volumes, rendering excessive water of intracellular origin. Chronic genetic IL-17A‒driven psoriasis mouse models underlined the role of IL-17A in dermal sodium accumulation and inflammation. Our data describe skin sodium as a pathophysiological feature of psoriasis, which could open new avenues for its treatment., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2022
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6. The extrinsic nature of double broadband photoluminescence from the BaTiO 3 perovskite: generation of white light emitters.
- Author
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Clabel H JL, Nicolodelli G, Lozano C G, G Rivera VA, Ferreira SO, Pinto AH, Li MS, and Marega E
- Abstract
The electronic properties of BaTiO
3 perovskite oxides are not completely understood, despite their excellent electro-optical performance and potential for light generation. Particularly, when there is multiple peak formation in the photoluminescence spectra, their origins are not discussed. Their luminescence spectra reveal an unexpected thermodynamic relationship between the core excitonic states and the surface of the BaTiO3 . These results give a broad insight into the origins of the emission properties of perovskite oxides. The self-trapped excitons contribution to the broadbands highlights their extrinsic origin. Through spectroscopy techniques and parallel factor analysis (PARAFAC) modeling, we demonstrate that additional broadbands are sensitive to extrinsic defects, type ν-CH3 , a product of decomposition of 2-propanol. The presence of C-H bonds shows the dependence with the calcination temperature and the increase of the lattice expansion coefficient until 4.7 × 10-6 K-1 resulting in the contribution to the change of band gap with the temperature ((dEg /dT)P ). In this work, we correlated the electronic properties of BaTiO3 with intrinsic and extrinsic defects and elucidated the presence of additional broadbands. This approach differentiates the contributions of excitonic states and surfaces, which is necessary to understand the electronic properties of perovskite oxides.- Published
- 2021
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7. Assessing the reporting of Dengue, Chikungunya and Zika to the National Surveillance System in Colombia from 2014-2017: A Capture-recapture analysis accounting for misclassification of arboviral diagnostics.
- Author
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Carabali M, Jaramillo-Ramirez GI, Rivera VA, Mina Possu NJ, Restrepo BN, and Zinszer K
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- Adolescent, Adult, Arboviruses classification, Chikungunya Fever mortality, Child, Child, Preschool, Cities epidemiology, Colombia epidemiology, Dengue mortality, Female, Humans, Male, Middle Aged, Population Surveillance, Regression Analysis, Young Adult, Zika Virus Infection mortality, Arboviruses pathogenicity, Chikungunya Fever epidemiology, Dengue epidemiology, Zika Virus Infection epidemiology
- Abstract
Background: Chikungunya, dengue, and Zika are three different arboviruses which have similar symptoms and are a major public health issue in Colombia. Despite the mandatory reporting of these arboviruses to the National Surveillance System in Colombia (SIVIGILA), it has been reported that the system captures less than 10% of diagnosed cases in some cities., Methodology/principal Findings: To assess the scope and degree of arboviruses reporting in Colombia between 2014-2017, we conducted an observational study of surveillance data using the capture-recapture approach in three Colombian cities. Using healthcare facility registries (capture data) and surveillance-notified cases (recapture data), we estimated the degree of reporting by clinical diagnosis. We fit robust Poisson regressions to identify predictors of reporting and estimated the predicted probability of reporting by disease and year. To account for the potential misclassification of the clinical diagnosis, we used the simulation extrapolation for misclassification (MC-SIMEX) method. A total of 266,549 registries were examined. Overall arboviruses' reporting ranged from 5.3% to 14.7% and varied in magnitude according to age and year of diagnosis. Dengue was the most notified disease (21-70%) followed by Zika (6-45%). The highest reporting rate was seen in 2016, an epidemic year. The MC-SIMEX corrected rates indicated underestimation of the reporting due to the potential misclassification bias., Conclusions: These findings reflect challenges on arboviruses' reporting, and therefore, potential challenges on the estimation of arboviral burden in Colombia and other endemic settings with similar surveillance systems., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2021
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8. Polyamines produced by Sinorhizobium meliloti Rm8530 contribute to symbiotically relevant phenotypes ex planta and to nodulation efficiency on alfalfa.
- Author
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Becerra-Rivera VA, Arteaga A, Leija A, Hernández G, and Dunn MF
- Subjects
- Bacterial Proteins genetics, Medicago sativa growth & development, Medicago sativa metabolism, Mutation, Nitrogen metabolism, Phenotype, Polysaccharides, Bacterial metabolism, Sinorhizobium meliloti metabolism, Medicago sativa microbiology, Ornithine Decarboxylase genetics, Polyamines metabolism, Root Nodules, Plant metabolism, Root Nodules, Plant microbiology, Sinorhizobium meliloti genetics
- Abstract
In nitrogen-fixing rhizobia, emerging evidence shows significant roles for polyamines in growth and abiotic stress resistance. In this work we show that a polyamine-deficient ornithine decarboxylase null mutant ( odc2 ) derived from Sinorhizobium meliloti Rm8530 had significant phenotypic differences from the wild-type, including greatly reduced production of exopolysaccharides (EPS; ostensibly both succinoglycan and galactoglucan), increased sensitivity to oxidative stress and decreased swimming motility. The introduction of the odc2 gene borne on a plasmid into the odc2 mutant restored wild-type phenotypes for EPS production, growth under oxidative stress and swimming. The production of calcofluor-binding EPS (succinoglycan) by the odc2 mutant was also completely or mostly restored in the presence of exogenous spermidine (Spd), norspermidine (NSpd) or spermine (Spm). The odc2 mutant formed about 25 % more biofilm than the wild-type, and its ability to form biofilm was significantly inhibited by exogenous Spd, NSpd or Spm. The odc2 mutant formed a less efficient symbiosis with alfalfa, resulting in plants with significantly less biomass and height, more nodules but less nodule biomass, and 25 % less nitrogen-fixing activity. Exogenously supplied Put was not able to revert these phenotypes and caused a similar increase in plant height and dry weight in uninoculated plants and in those inoculated with the wild-type or odc2 mutant. We discuss ways in which polyamines might affect the phenotypes of the odc2 mutant.
- Published
- 2020
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9. Soil hydrology drives ecological niche differentiation in a native prairie microbiome.
- Author
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Griffin JS, Haug LA, Rivera VA, Gonzalez LMH, Kelly JJ, Miller WM, Wells GF, and Packman AI
- Subjects
- Ammonia metabolism, Biodiversity, Climate Change, Hydrology, Soil Microbiology, Wetlands, Grassland, Microbiota, Soil chemistry, Water analysis
- Abstract
While the impacts of soil moisture on soil microbiome diversity and composition are well characterized, the influence of hydrological regime has been overlooked. As precipitation patterns are altered by climate change, understanding the impact of soil hydrology on community structure and function is critical. In this work, water level was continuously monitored for over a year in a Midwestern prairie-wetland at 10 cm depth increments up to a depth of 120 cm in 10 locations. We analyzed microbiome composition and edaphic factors in soil cores collected from this unique spatially distributed, longitudinal data set. We demonstrate that the fraction of time that each sample was inundated explains more variability in diversity and composition across this site than other commonly assessed edaphic factors, such as soil pH or depth. Finally, we show that these compositional changes influence abundance of ammonia oxidizers. The observed patterns in community composition and diversity are fundamentally regulated by the interaction of water with a structured landscape, particularly an elevated sand ridge characterized by drier conditions and a lower-lying wetland with more clayey soils. Similar processes are generally expected to influence the biogeography of many terrestrial environments, as morphology, hydrology and soil properties generally co-vary., (© FEMS 2019.)
- Published
- 2020
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10. Mast cells are critical for controlling the bacterial burden and the healing of infected wounds.
- Author
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Zimmermann C, Troeltzsch D, Giménez-Rivera VA, Galli SJ, Metz M, Maurer M, and Siebenhaar F
- Subjects
- Animals, Anti-Bacterial Agents pharmacology, Cells, Cultured, Humans, Interleukin-6 pharmacology, Keratinocytes drug effects, Mast Cells cytology, Mice, Pseudomonas Infections immunology, Pseudomonas Infections microbiology, Skin drug effects, Wound Healing drug effects, Wound Infection immunology, Wound Infection microbiology, Keratinocytes immunology, Mast Cells immunology, Pseudomonas Infections prevention & control, Pseudomonas aeruginosa immunology, Skin immunology, Wound Healing immunology, Wound Infection prevention & control
- Abstract
Skin wound infections are a significant health problem, and antibiotic resistance is on the rise. Mast cells (MCs) have been shown to contribute to host-defense responses in certain bacterial infections, but their role in skin wound superinfection is unknown. We subjected 2 MC-deficient mouse strains to Pseudomonas aeruginosa skin wound infection and found significantly delayed wound closure in infected skin wounds. This delay was associated with impaired bacterial clearance in the absence of MCs. Engraftment of MCs restored both bacterial clearance and wound closure. Bacterial killing was dependent on IL-6 released from MCs, and engraftment with IL-6-deficient MCs failed to control wound infection. Treatment with recombinant IL-6 enhanced bacterial killing and resulted in the control of wound infection and normal wound healing in vivo. Taken together, our results demonstrate a defense mechanism for boosting host innate immune responses, namely effects of MC-derived IL-6 on antimicrobial functions of keratinocytes., Competing Interests: The authors declare no conflict of interest.
- Published
- 2019
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11. Polyamine biosynthesis and biological roles in rhizobia.
- Author
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Becerra-Rivera VA and Dunn MF
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, Gene Expression Regulation, Bacterial, Medicago sativa microbiology, Sinorhizobium meliloti genetics, Sinorhizobium meliloti growth & development, Polyamines metabolism, Sinorhizobium meliloti metabolism
- Abstract
Polyamines are ubiquitous molecules containing two or more amino groups that fulfill varied and often essential physiological and regulatory roles in all organisms. In the symbiotic nitrogen-fixing bacteria known as rhizobia, putrescine and homospermidine are invariably produced while spermidine and norspermidine synthesis appears to be restricted to the alfalfa microsymbiont Sinorhizobium meliloti. Studies with rhizobial mutants deficient in the synthesis of one or more polyamines have shown that these compounds are important for growth, stress resistance, motility, exopolysaccharide production and biofilm formation. In this review, we describe these studies and examine how polyamines are synthesized and regulated in rhizobia., (© FEMS 2019.)
- Published
- 2019
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12. Live imaging of collagen deposition during experimental hepatic schistosomiasis and recovery: a view on a dynamic process.
- Author
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Harvie MCG, McManus DP, You H, Rivera VA, Nawaratna SK, MacDonald KPA, Ramm GA, and Gobert GN
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- Animals, Collagen genetics, Disease Models, Animal, Female, Histocytochemistry, Liver diagnostic imaging, Liver metabolism, Liver parasitology, Liver Cirrhosis diagnostic imaging, Liver Cirrhosis parasitology, Luciferases genetics, Luciferases metabolism, Male, Mice, Mice, Transgenic, Optical Imaging, Schistosoma japonicum, Schistosomiasis complications, Schistosomiasis diagnostic imaging, Schistosomiasis parasitology, Collagen metabolism, Liver Cirrhosis metabolism, Schistosomiasis metabolism
- Abstract
Hepatic fibrosis is the central cause of chronic clinical pathology resulting from infection by the blood flukes Schistosoma japonicum or S. mansoni. Much has been elucidated regarding the molecular, cellular and immunological responses that correspond to the formation of the granulomatous response to trapped schistosome eggs. A central feature of this Th2 response is the deposition of collagen around the periphery of the granuloma. To date, traditional histology and transcriptional methods have been used to quantify the deposition of collagen and to monitor the formation of the hepatic granuloma during experimental animal models of schistosomiasis. We have investigated the dynamic nature of granuloma formation through the use of a transgenic mouse model (B6.Collagen 1(A) luciferase mice (B6.Coll 1A-luc
+ )). With this model and whole-animal bioluminescence imaging, we followed the deposition of collagen during an active schistosome infection with Chinese and Philippines geographical strains of S. japonicum and after clearance of the adult parasites by the drug praziquantel. Individual mice were re-imaged over the time course to provide robust real-time quantitation of the development of chronic fibrotic disease. This model provides an improved method to follow the course of hepatic schistosomiasis-induced hepatic pathology and effectively supports the current dogma of the formation of hepatic fibrosis, originally elucidated from static traditional histology. This study demonstrates the first use of the B6.Coll 1A-luc+ mouse to monitor the dynamics of disease development and the treatment of pathogen-induced infection with the underlying pathology of fibrosis.- Published
- 2019
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13. Response rate profiles for major depressive disorder: Characterizing early response and longitudinal nonresponse.
- Author
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Kelley ME, Dunlop BW, Nemeroff CB, Lori A, Carrillo-Roa T, Binder EB, Kutner MH, Rivera VA, Craighead WE, and Mayberg HS
- Subjects
- Adult, Aged, Brain-Derived Neurotrophic Factor genetics, Depressive Disorder, Major psychology, Disease Progression, Female, Humans, Latent Class Analysis, Male, Middle Aged, Receptor, Serotonin, 5-HT2A genetics, Receptors, Kainic Acid genetics, Serotonin Plasma Membrane Transport Proteins genetics, Tacrolimus Binding Proteins genetics, Treatment Outcome, Young Adult, Antidepressive Agents therapeutic use, Citalopram therapeutic use, Cognitive Behavioral Therapy, Depressive Disorder, Major therapy, Duloxetine Hydrochloride therapeutic use
- Abstract
Background: Definition of response is critical when seeking to establish valid predictors of treatment success. However, response at the end of study or endpoint only provides one view of the overall clinical picture that is relevant in testing for predictors. The current study employed a classification technique designed to group subjects based on their rate of change over time, while simultaneously addressing the issue of controlling for baseline severity., Methods: A set of latent class trajectory analyses, incorporating baseline level of symptoms, were performed on a sample of 344 depressed patients from a clinical trial evaluating the efficacy of cognitive behavior therapy and two antidepressant medications (escitalopram and duloxetine) in patients with major depressive disorder., Results: Although very few demographic and illness-related features were associated with response rate profiles, the aggregated effect of candidate genetic variants previously identified in large pharmacogenetic studies and meta-analyses showed a significant association with early remission as well as nonresponse. These same genetic scores showed a less compelling relationship with endpoint response categories. In addition, consistent nonresponse throughout the study treatment period was shown to occur in different subjects than endpoint nonresponse, which was verified by follow-up augmentation treatment outcomes., Conclusions: When defining groups based on the rate of change, controlling for baseline depression severity may help to identify the clinically relevant distinctions of early response on one end and consistent nonresponse on the other., (© 2018 Wiley Periodicals, Inc.)
- Published
- 2018
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14. Polyamines are required for normal growth in Sinorhizobium meliloti.
- Author
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Becerra-Rivera VA, Bergström E, Thomas-Oates J, and Dunn MF
- Subjects
- Amino Acids metabolism, Bacterial Proteins genetics, Bacterial Proteins metabolism, Culture Media, Gene Expression Regulation, Bacterial, Genetic Complementation Test, Mutation, Ornithine Decarboxylase genetics, Polyamines analysis, Putrescine metabolism, Sinorhizobium meliloti enzymology, Spermidine analogs & derivatives, Spermidine metabolism, Transcription, Genetic, Ornithine Decarboxylase metabolism, Polyamines metabolism, Sinorhizobium meliloti growth & development, Sinorhizobium meliloti metabolism
- Abstract
Polyamines (PAs) are ubiquitous polycations derived from basic l-amino acids whose physiological roles are still being defined. Their biosynthesis and functions in nitrogen-fixing rhizobia such as Sinorhizobium meliloti have not been extensively investigated. Thin layer chromatographic and mass spectrometric analyses showed that S. meliloti Rm8530 produces the PAs, putrescine (Put), spermidine (Spd) and homospermidine (HSpd), in their free forms and norspermidine (NSpd) in a form bound to macromolecules. The S. meliloti genome encodes two putative ornithine decarboxylases (ODC) for Put synthesis. Activity assays with the purified enzymes showed that ODC2 (SMc02983) decarboxylates both ornithine and lysine. ODC1 (SMa0680) decarboxylates only ornithine. An odc1 mutant was similar to the wild-type in ODC activity, PA production and growth. In comparison to the wild-type, an odc2 mutant had 45 % as much ODC activity and its growth rates were reduced by 42, 14 and 44 % under non-stress, salt stress or acid stress conditions, respectively. The odc2 mutant produced only trace levels of Put, Spd and HSpd. Wild-type phenotypes were restored when the mutant was grown in cultures supplemented with 1 mM Put or Spd or when the odc2 gene was introduced in trans. odc2 gene expression was increased under acid stress and reduced under salt stress and with exogenous Put or Spd. An odc1 odc2 double mutant had phenotypes similar to the odc2 mutant. These results indicate that ODC2 is the major enzyme for Put synthesis in S. meliloti and that PAs are required for normal growth in vitro.
- Published
- 2018
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15. Mast Cells Limit the Exacerbation of Chronic Allergic Contact Dermatitis in Response to Repeated Allergen Exposure.
- Author
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Gimenez-Rivera VA, Siebenhaar F, Zimmermann C, Siiskonen H, Metz M, and Maurer M
- Subjects
- Allergens immunology, Animals, CD8-Positive T-Lymphocytes pathology, Chronic Disease, Cytokines genetics, Cytokines immunology, Dermatitis, Contact genetics, Dermatitis, Contact pathology, Disease Models, Animal, Mast Cells pathology, Mice, Mice, Transgenic, Oxazolone adverse effects, Oxazolone pharmacology, Proto-Oncogene Proteins c-kit genetics, Proto-Oncogene Proteins c-kit immunology, Skin pathology, Allergens toxicity, CD8-Positive T-Lymphocytes immunology, Dermatitis, Contact immunology, Immunologic Memory, Mast Cells immunology, Skin immunology
- Abstract
Allergic contact dermatitis is a chronic T cell-driven inflammatory skin disease that is caused by repeated exposure to contact allergens. Based on murine studies of acute contact hypersensitivity, mast cells (MCs) are believed to play a role in its pathogenesis. The role of MCs in chronic allergic contact dermatitis has not been investigated, in part because of the lack of murine models for chronic contact hypersensitivity. We developed and used a chronic contact hypersensitivity model in wild-type and MC-deficient mice and assessed skin inflammatory responses to identify and characterize the role of MCs in chronic allergic contact dermatitis. Ear swelling chronic contact hypersensitivity responses increased markedly, up to 4-fold, in MC-deficient Kit
W-sh/W-sh (Sash) and MCPT5-Cre+ iDTR+ mice compared with wild-type mice. Local engraftment with MCs protected Sash mice from exacerbated ear swelling after repeated oxazolone challenge. Chronic contact hypersensitivity skin of Sash mice exhibited elevated levels of IFN-γ, IL-17α, and IL-23, as well as increased accumulation of Ag-specific IFN-γ-producing CD8+ tissue-resident memory T (TRM ) cells. The CD8+ T cell mitogen IL-15, which was increased in oxazolone-challenged skin of Sash mice during the accumulation of cutaneous TRM cells, was efficiently degraded by MCs in vitro. MCs protect from the exacerbated allergic skin inflammation induced by repeated allergen challenge, at least in part, via effects on CD8+ TRM cells. MCs may notably influence the course of chronic allergic contact dermatitis. A better understanding of their role and the underlying mechanisms may lead to better approaches for the treatment of this common, disabling, and costly condition., (Copyright © 2016 by The American Association of Immunologists, Inc.)- Published
- 2016
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16. Plasmon-photon conversion to near-infrared emission from Yb(3+): (Au/Ag-nanoparticles) in tungsten-tellurite glasses.
- Author
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Rivera VA, Ledemi Y, Pereira-da-Silva MA, Messaddeq Y, and Marega E Jr
- Abstract
This manuscript reports on the interaction between (2)F5/2→(2)F7/2 radiative transition from Yb(3+) ions and localized surface plasmon resonance (from gold/silver nanoparticles) in a tungsten-tellurite glass. Such an interaction, similar to the down-conversion process, results in the Yb(3+) emission in the near-infrared region via resonant and non-resonant energy transfers. We associated such effects with the dynamic coupling described by the variations generated by the Hamiltonian HDC in either the oscillator strength, or the local crystal field, i.e. the line shape changes in the emission band. Here, the Yb(3+) ions emission is achieved through plasmon-photon coupling, observable as an enhancement or quenching in the luminescence spectra. Metallic nanoparticles have light-collecting capability in the visible spectrum and can accumulate almost all the photon energy on a nanoscale, which enable the excitation and emission of the Yb(3+) ions in the near-infrared region. This plasmon-photon conversion was evaluated from the cavity's quality factor (Q) and the coupling (g) between the nanoparticles and the Yb(3+) ions. We have found samples of low-quality cavities and strong coupling between the nanoparticles and the Yb(3+) ions. Our research can be extended towards the understanding of new plasmon-photon converters obtained from interactions between rare-earth ions and localized surface plasmon resonance.
- Published
- 2016
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17. Control of the radiative properties via photon-plasmon interaction in Er3+ -Tm3+ -codoped tellurite glasses in the near infrared region.
- Author
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Rivera VA, Ledemi Y, El-Amraoui M, Messaddeq Y, and Marega E
- Abstract
The novelty of this paper is that it reports on the tuning of the spectral properties of Er3+ -Tm3+ ions in tellurite glasses in the near-infrared region through the incorporation of silver or gold nanoparticles. These noble metal nanoparticles can improve the emission intensity and expand the bandwidth of the luminescence spectrum centered at 1535 nm, covering practically all the optical telecommunication bands (S, C + L and U), and extended up to 2010 nm wavelength under excitation by a 976 nm laser diode. Both effects are obtained by the combined emission of Er3+ and Tm3+ ions due to efficient energy transfer processes promoted by the presence of silver or gold nanoparticles for the (Er3+)4I(11/2)→(Tm3+)3H5, (Er3+)4I(13/2)→(Tm3+)3H4 and (Er3+)4I(13/2)→(Tm3+)3F4 transitions. The interactions between the electronic transitions of Er3+ and Tm3+ ions that provide a tunable emission are associated with the dynamic coupling mechanism described by the variations generated by the Hamiltonian H DC in either the oscillator strength or the local crystal field, i.e. the line shape changes in the near-infrared emission band. The Hamiltonian is expressed as eigenmodes associated with the density of the conduction electron generated by the different nanoparticles through its collective free oscillations at each resonance frequency of the nanoparticle and their geometric dependence. A complete description of photon-plasmon interactions of noble metal nanoparticles with the Er3+ and Tm3+ ions is provided.
- Published
- 2014
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18. Mast cell-mediated reactions in vivo.
- Author
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Giménez-Rivera VA, Metz M, and Siebenhaar F
- Subjects
- Anaphylaxis, Animals, Body Temperature, Cell Degranulation, Dermatitis, Contact diagnosis, Mice, Skin Tests methods, Dermatitis, Contact immunology, Mast Cells immunology, Passive Cutaneous Anaphylaxis immunology
- Abstract
Mast cells are involved in many physiological reactions in which their functions can be very diverse. Models of allergic skin inflammation and systemic anaphylactic reactions in mice are validated methods in which the role of mast cells is well established. In this chapter, we therefore present protocols for passive cutaneous anaphylaxis and contact hypersensitivity, i.e., models which can be used to identify and characterize the role of mast cells as well as mast cell mediators and receptors in allergic IgE-dependent and -independent skin inflammation, and for passive systemic anaphylaxis, a model ideally suited to characterize the systemic effects of mast cell-derived mediators and mast cell receptors.
- Published
- 2014
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19. Predictors of remission in depression to individual and combined treatments (PReDICT): study protocol for a randomized controlled trial.
- Author
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Dunlop BW, Binder EB, Cubells JF, Goodman MM, Kelley ME, Kinkead B, Kutner M, Nemeroff CB, Newport DJ, Owens MJ, Pace TW, Ritchie JC, Rivera VA, Westen D, Craighead WE, and Mayberg HS
- Subjects
- Adolescent, Adult, Aged, Biomarkers, Brain pathology, Depressive Disorder, Major genetics, Depressive Disorder, Major pathology, Drug Therapy, Combination, Duloxetine Hydrochloride, Female, Genetic Testing, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Personality, Predictive Value of Tests, Remission Induction, Research Design, Treatment Outcome, Young Adult, Antidepressive Agents therapeutic use, Antidepressive Agents, Second-Generation therapeutic use, Citalopram therapeutic use, Depressive Disorder, Major drug therapy, Thiophenes therapeutic use
- Abstract
Background: Limited controlled data exist to guide treatment choices for clinicians caring for patients with major depressive disorder (MDD). Although many putative predictors of treatment response have been reported, most were identified through retrospective analyses of existing datasets and very few have been replicated in a manner that can impact clinical practice. One major confound in previous studies examining predictors of treatment response is the patient's treatment history, which may affect both the predictor of interest and treatment outcomes. Moreover, prior treatment history provides an important source of selection bias, thereby limiting generalizability. Consequently, we initiated a randomized clinical trial designed to identify factors that moderate response to three treatments for MDD among patients never treated previously for the condition., Methods/design: Treatment-naïve adults aged 18 to 65 years with moderate-to-severe, non-psychotic MDD are randomized equally to one of three 12-week treatment arms: (1) cognitive behavior therapy (CBT, 16 sessions); (2) duloxetine (30-60 mg/d); or (3) escitalopram (10-20 mg/d). Prior to randomization, patients undergo multiple assessments, including resting state functional magnetic resonance imaging (fMRI), immune markers, DNA and gene expression products, and dexamethasone-corticotropin-releasing hormone (Dex/CRH) testing. Prior to or shortly after randomization, patients also complete a comprehensive personality assessment. Repeat assessment of the biological measures (fMRI, immune markers, and gene expression products) occurs at an early time-point in treatment, and upon completion of 12-week treatment, when a second Dex/CRH test is also conducted. Patients remitting by the end of this acute treatment phase are then eligible to enter a 21-month follow-up phase, with quarterly visits to monitor for recurrence. Non-remitters are offered augmentation treatment for a second 12-week course of treatment, during which they receive a combination of CBT and antidepressant medication. Predictors of the primary outcome, remission, will be identified for overall and treatment-specific effects, and a statistical model incorporating multiple predictors will be developed to predict outcomes., Discussion: The PReDICT study's evaluation of biological, psychological, and clinical factors that may differentially impact treatment outcomes represents a sizeable step toward developing personalized treatments for MDD. Identified predictors should help guide the selection of initial treatments, and identify those patients most vulnerable to recurrence, who thus warrant maintenance or combination treatments to achieve and maintain wellness.
- Published
- 2012
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20. Influence of film thickness on the optical transmission through subwavelength single slits in metallic thin films.
- Author
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Ferri FA, Rivera VA, Osorio SP, Silva OB, Zanatta AR, Borges BH, Weiner J, and Marega E Jr
- Abstract
Silver and gold films with thicknesses in the range of 120-450 nm were evaporated onto glass substrates. A sequence of slits with widths varying between 70 and 270 nm was milled in the films using a focused gallium ion beam. We have undertaken high-resolution measurements of the optical transmission through the single slits with 488.0 nm (for Ag) and 632.8 nm (for Au) laser sources aligned to the optical axis of a microscope. Based on the present experimental results, it was possible to observe that (1) the slit transmission is notably affected by the film thickness, which presents a damped oscillatory behavior as the thickness is augmented, and (2) the transmission increases linearly with increasing slit width for a fixed film thickness., (© 2011 Optical Society of America)
- Published
- 2011
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21. Association screening in the Epidermal Differentiation Complex (EDC) identifies an SPRR3 repeat number variant as a risk factor for eczema.
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Marenholz I, Rivera VA, Esparza-Gordillo J, Bauerfeind A, Lee-Kirsch MA, Ciechanowicz A, Kurek M, Piskackova T, Macek M, and Lee YA
- Subjects
- Age of Onset, Amino Acid Sequence, Base Sequence, Child, Preschool, Codon, Nonsense, Codon, Terminator genetics, Databases, Genetic, Eczema pathology, Epidermis pathology, Filaggrin Proteins, Frameshift Mutation, Genetic Testing, Genetic Variation, Humans, Infant, Linkage Disequilibrium, Molecular Sequence Data, Polymorphism, Genetic, Risk Factors, Cornified Envelope Proline-Rich Proteins genetics, DNA Repeat Expansion genetics, Eczema epidemiology, Eczema genetics, Epidermis physiology
- Abstract
The genetically determined impairment of the skin barrier is a primary cause of eczema. As numerous genes essential for an intact epidermis reside within the epidermal differentiation complex (EDC), we screened the National Center for Biotechnology Information (NCBI) database for putatively functional polymorphisms in the EDC genes and tested them for association with eczema. We identified 20 polymorphisms with predicted major impact on protein function. Of these, 4 were validated in 94 eczema patients: a nonsense mutation in FLG2 (rs12568784), a stop codon mutation in LCE1D (rs41268500), a 24-bp deletion in SPRR3 (rs28989168), and a frameshift mutation in S100A3 (rs11390146). The minor allele frequencies were 15.1, 6.1, 47.2, and 0.4%, respectively. Association testing of the validated polymorphisms in 555 eczema patients and 375 controls identified a significant effect of rs28989168 (SPRR3) on eczema. The association was replicated in another 1,314 cases and 1,322 controls, yielding an overall odds ratio of 1.30 (95% confidence interval 1.12-1.51; P=0.00067) for a dominant mode of inheritance. Small proline-rich proteins (SPRRs) are crossbridging proteins in the cornified cell envelope (CE), which provides the main barrier function of stratified squamous epithelia. The SPRR3 variant associated with eczema carried an extra 24-bp repeat in the central domain, which may alter the physical properties of the CE.
- Published
- 2011
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22. Localized surface plasmon resonance interaction with Er3+-doped tellurite glass.
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Rivera VA, Osorio SP, Ledemi Y, Manzani D, Messaddeq Y, Nunes LA, and Marega E Jr
- Abstract
We show the annealing effect on silver and Erbium-doped tellurite glasses in the formation of nanoparticles (NPs) of silver, produced by the reduction of silver (Ag+ → Ag0), aiming to an fluorescence enhancement. The absorption spectra show typical Localized Surface Plasmon Resonance (LSPR) band of Ag0 NP in addition to the distinctive absorption peaks of Er3+ ions. Both observations demonstrate that the photoluminescence enhancement is due to the coupling of dipoles formed by NPs with the Er3+ 4I(13/2) → 4I(15/2) transition. This plasmon energy transfer to the Er3+ ions was observed in the fluorescence spectrum with a blue-shift of the peaks.
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- 2010
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23. Temperature oscillations of magnetization observed in nanofluid ferromagnetic graphite.
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Sergeenkov S, Souza NS, Speglich C, Rivera VA, Cardoso CA, Pardo H, Mombrú AW, and Araújo-Moreira FM
- Abstract
We report on unusual magnetic properties observed for nanofluid room temperature ferromagnetic graphite (with an average particle size of [Formula: see text] nm). More precisely, the measured magnetization exhibits a low temperature anomaly (attributed to the manifestation of finite size effects below the quantum temperature [Formula: see text]) as well as pronounced temperature oscillations above T = 50 K (attributed to manifestation of the hard-sphere type of pair correlations between ferromagnetic particles in the nanofluid).
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- 2009
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24. Synthetic and Mechanistic Studies of Strained Heterocycle Opening Reactions Mediated by Zirconium(IV) Imido Complexes.
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Blum SA, Rivera VA, Ruck RT, Michael FE, and Bergman RG
- Abstract
The reactions of the bis(cyclopentadienyl)(tert-butylimido)zirconium complex (Cp(2)Zr=N-t-Bu)(THF) (1) with epoxides, aziridines, and episulfides were investigated. Heterocycles without accessible beta-hydrogens undergo insertion/protonation of the C-X bond to produce 1,2-amino alcohols (X = O) and 1,2-diamines (X = NR), whereas heterocycles with accessible beta-hydrogens undergo elimination/protonation to produce allylic alcohols (X = O) and allylic sulfides (X = S). Mechanistic investigations support a stepwise pathway with zwitterionic intermediates for the first reaction class and a concerted pathway for the second reaction class. Additionally, the feasibility of chirality transfer from the planar-chiral ebthi (ebthi = ethylenebis(tetrahydroindenyl)) ligand was demonstrated with a chiral analogue, (ebthi)-Zr=NAr(THF) (Ar = 2,6-dimethylphenyl), 2, through the diastereoselective ring opening of meso epoxides.
- Published
- 2005
- Full Text
- View/download PDF
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