455 research outputs found
Beyond the mask of deference: Exploring the relationship between ruptures and transference in a single-case study
Metamorphic rocks from Córdoba (Argentina) and the alkali-silica reaction
The “Sierras Pampeanas de Córdoba” (Argentina) is an igneous-metamorphic complex affected by shear zones. The deformation varies from one sector to another producing microstructures that affect the internal order and the size of the crystals, generating sites susceptible to suffering the attack of alkaline solutions. This process, known as alkali-silica reaction (ASR), occurs between cryptocrystalline, strained and/or amorphous silica compounds and the alkalis in the concrete pore solution, and forms a gel that increases its volume producing cracks and concrete deterioration.
To evaluate the potential reactivity of rocks from the Córdoba region, the petrographic method (ASTM C 295), the accelerated mortar bar test method (ASTM C 1260) and the determination of dissolved silica (ASTM C 289) were carried out. The preliminary results allow determining a positive linear correlation (R2 = 0.86) between the expansion in mortar bars and leached silica. These values grow with deformation intensity increment in quartz-bearing rocks
Rocas de las sierras de Córdoba como agregados para el hormigón.
En la actualidad existen abundantes antecedentes respecto a la reacción álcali-agregado (RAA) en Argentina, pero son escasos los publicados respecto al comportamiento de hormigones con agregados que provengan de las Sierras de Córdoba (Locati 2006; Locati et al. 2008; Bonalumi et al. 2009).
La reacción álcali-sílice se produce cuando ciertos agregados silíceos de estructura amorfa, desordenada o pobremente cristalina, reaccionan con los oxhidrilos (de los hidróxidos alcalinos) presentes en la solución de poro del hormigón a pH elevado, formando un gel higroscópico que es ávido en agua y se expande en presencia de Ca2+ (Batic y Sota 2001). Es por esto que resulta de gran interés evaluar el comportamiento de diferentes tipos de rocas, especialmente las que han sufrido procesos de deformación que afectaron su microestructura original.
Debido a que el sector oriental de las Sierras Pampeanas es el área más cercana a la Ciudad de Córdoba y es de donde provienen la mayoría de los agregados pétreos triturados que se utilizan para la construcción en dicha zona, se estudiaron diferentes litologías de explotación actual y de áreas potenciales, a fin de determinar su reactividad
A WebGIS tool for the dissemination of earthquake data
In 2004 a new seismic hazard map of Italy (MPS Working Group, 2004) has been released by a task force that produced an
amount of new or updated data, such as a new version of the earthquake catalogue (CPTI04; CPTI Working Group, 2004)
and an updated seismogenic zonation. A set of WebGIS tools has been designed for the data dissemination to the
scientific community and the general public.
The design of the WebGIS tools focused first on the consultation of the DBM04 macroseismic database (DBM Working
Group, 2005), which contains the macroseismic intensity data-points (IDP) of the earthquakes listed in the CPTI04
catalogue.
The WebGIS tool design and development process had to fulfill: 1) simplicity, 2) responsiveness and 3) readiness for
future extensions.
The specific requirements for the macroseismic database consultation interface were:
- data access by place and by earthquake;
- IDP maps with queryable points;
- data download in both tabular and map format;
- easily upgradable content;
- quick and user friendly interface
HIV-1 Coreceptor Activity of CCR5 and Its Inhibition by Chemokines: Independence from G Protein Signaling and Importance of Coreceptor Downmodulation
AbstractHIV-1 infection requires the presence of specific chemokine receptors on CD4+ target cells to enable the fusion reactions involved in virus entry. CCR5 is a major fusion coreceptor for macrophage-tropic HIV-1 isolates. HIV-1 entry and fusion are mediated by the viral envelope glycoprotein (Env) and are inhibited by CCR5 ligands, but the mechanisms are unknown. Here, we test the role of G protein signaling and CCR5 surface downmodulation by two separate approaches: direct inactivation of CCR5 signaling by mutagenesis and inactivation of Gi-type G proteins with pertussis toxin. A CCR5 mutant lacking the last 45 amino acids of the cytoplasmic C-terminus (CCR5306) was created that was expressed on transfected cells at levels comparable to cells expressing CCR5 and displayed normal chemokine binding affinity. CCR5 ligands induced calcium flux and receptor downmodulation in cells expressing CCR5, but not in cells expressing CCR5306. Nevertheless, CCR5 or CCR5306, when coexpressed with CD4, supported comparable HIV-1 Env-mediated cell fusion. Consistent with this, treatment of CCR5-expressing cells with pertussis toxin completely blocked ligand-induced transient calcium flux, but did not affect Env-mediated cell fusion or HIV-1 infection. Also, pertussis toxin did not block chemokine inhibition of Env-mediated cell fusion or HIV-1 infection. However, chemokines inhibited Env-mediated cell fusion less efficiently for CCR5306than for CCR5. We conclude that the C-terminal domain of CCR5 is critical for G protein signaling and receptor downmodulation from the surface, but that neither function is required for CCR5 fusion coreceptor activity. The contrasting phenotypes of CCR5 and CCR5306suggest that coreceptor downmodulation and direct blockage of Env interaction sites both contribute to chemokine inhibition of HIV-1 infection
Reciprocal interference between the NRF2 and LPS signaling pathways on the immune-metabolic phenotype of peritoneal macrophages
The metabolic and immune adaptation to extracellular signals allows macrophages to carry out specialized functions involved in immune protection and tissue homeostasis. Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that coordinates cell redox and metabolic responses to stressors. However, the individual and concomitant activation of NRF2 and inflammatory pathways have been poorly investigated in isolated macrophages. We here took advantage of reporter mice for the transcriptional activities of NRF2 and nuclear factor-kB (NF\u3baB), a key transcription factor in inflammation, and observe a persisting reciprocal interference in the response of peritoneal macrophages to the respective activators, tert-Butylhydroquinone (tBHQ) and lipopolysaccharide (LPS). When analyzed separately by gene expression studies, these pathways trigger macrophage-specific metabolic and proliferative target genes that are associated with tBHQ-induced pentose phosphate pathway (PPP) with no proliferative response, and with opposite effects observed with LPS. Importantly, the simultaneous administration of tBHQ + LPS alters the effects of each individual pathway in a target gene-specific manner. In fact, this co-treatment potentiates the effects of tBHQ on the antioxidant enzyme, HMOX1, and the antibacterial enzyme, IRG1, respectively; moreover, the combined treatment reduces tBHQ activity on the glycolytic enzymes, TALDO1 and TKT, and decreases LPS effects on the metabolic enzyme IDH1, the proliferation-related proteins KI67 and PPAT, and the inflammatory cytokines IL-1\u3b2, IL-6, and TNF\u3b1. Altogether, our results show that the activation of NRF2 redirects the metabolic, immune, and proliferative response of peritoneal macrophages to inflammatory signals, with relevant consequences for the pharmacological treatment of diseases that are associated with unopposed inflammatory responses
A WebGIS tool for the dissemination of earthquake data
In 2004 a new seismic hazard map of Italy (MPS Working Group, 2004) has been released by a task force that produced an
amount of new or updated data, such as a new version of the earthquake catalogue (CPTI04; CPTI Working Group, 2004)
and an updated seismogenic zonation. A set of WebGIS tools has been designed for the data dissemination to the
scientific community and the general public.
The design of the WebGIS tools focused first on the consultation of the DBM04 macroseismic database (DBM Working
Group, 2005), which contains the macroseismic intensity data-points (IDP) of the earthquakes listed in the CPTI04
catalogue.
The WebGIS tool design and development process had to fulfill: 1) simplicity, 2) responsiveness and 3) readiness for
future extensions.
The specific requirements for the macroseismic database consultation interface were:
- data access by place and by earthquake;
- IDP maps with queryable points;
- data download in both tabular and map format;
- easily upgradable content;
- quick and user friendly interface
Migration of dendritic cells across blood and lymphatic endothelial barriers.
7openopenDel Prete A; Locati M; Otero K; Riboldi E; Mantovani A; Vecchi A; Sozzani S.DEL PRETE, Annalisa; Locati, M; Otero, K; Riboldi, E; Mantovani, A; Vecchi, A; Sozzani, Silvan
ER alpha-independent NRF2-mediated immunoregulatory activity of tamoxifen
Sex differences in immune-mediated diseases are linked to the activity of estrogens on innate immunity cells,
including macrophages. Tamoxifen (TAM) is a selective estrogen receptor modulator (SERM) used in estrogen
receptor-alpha (ERα)-dependent breast cancers and off-target indications such as infections, although the immune activity of TAM and its active metabolite, 4-OH tamoxifen (4HT), is poorly characterized. Here, we aimed
at investigating the endocrine and immune activity of these SERMs in macrophages. Using primary cultures of
female mouse macrophages, we analyzed the expression of immune mediators and activation of effector functions in competition experiments with SERMs and 17β-estradiol (E2) or the bacterial endotoxin LPS. We observed
that 4HT and TAM induce estrogen antagonist effects when used at nanomolar concentrations, while pharmacological concentrations that are reached by TAM in clinical settings regulate the expression of VEGFα and other
immune activation genes by ERα- and G protein-coupled receptor 1 (GPER1)-independent mechanisms that
involve NRF2 through PI3K/Akt-dependent mechanisms. Importantly, we observed that SERMs potentiate cell
phagocytosis and modify the effects of LPS on the expression of inflammatory cytokines, such as TNFα and IL1β,
with an overall increase in cell inflammatory phenotype, further sustained by potentiation of IL1β secretion
through caspase-1 activation
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