The synthesis, structure, and catalytic activity of a Ti(II)/Ti(III) inverted sandwich compound are presented in this study. Synthesis of the arene-bridged dititanium compound begins with the ...preparation of the titanium(IV) precursor TiCl2(MesPDA)(thf)2 (MesPDA = N,N′-bis(2,4,6-trimethylphenyl)-o-phenylenediamide) (2). The reduction of 2 with sodium metal results in species {Ti(MesPDA)(thf)}2(μ-Cl)3{Na} (3) in oxidation state III. To achieve the lower oxidation state II, 2 undergoes reduction through alkylation with lithium cyclopentyl. This alkylation approach triggers a cascade of reactions, including β-hydride abstraction/elimination, hydrogen evolution, and chemical reduction, to generate the Ti(II)/Ti(III) compound Li(thf)4(TiMesPDA)2(μ–η6: η6-C6H6) (4). X-ray and EPR characterization confirms the mixed-valence states of the titanium species. Compound 4 catalyzes a mild, efficient, and regiospecific cyclotrimerization of alkynes to form 1,3,5-substituted arenes. Kinetic data support a mechanism involving a binuclear titanium arene compound, similar to compound 4, as the resting state. The active catalyst promotes the oxidative coupling of two alkynes in the rate-limiting step, followed by a rapid 4 + 2 cycloaddition to form the arene product. Computational analysis of the resting state for the cycloaddition of trimethylsilylacetylene indicates a thermodynamic preference for stabilizing the 1,3,5-arene within the space between the two TiMesPDA fragments, consistent with the observed regioselectivity.
This work explores in depth the simultaneous self‐assembly and mineralization of type I collagen by a base‐acid neutralization technique to prepare biomimetic collagen‐apatite fibrils with varying ...mineralization extent and doped with luminescent bactericidal Tb3+ ions. Two variants of the method are tested: base‐acid titration, a solution of Ca(OH)2 is added dropwise to a stirred solution containing type I collagen dispersed in H3PO4; and direct mixing, the Ca(OH)2 solution is added by fast dripping onto the acidic solution. Only the direct mixing variant yielded an effective control of calcium phosphate polymorphism. Luminescence spectroscopy reveals the long luminescence lifetime and high relative luminescence intensity of the Tb3+‐doped materials, while two‐photon confocal fluorescence microscopy shows the characteristic green fluorescence light when using excitation wavelength of 458 nm, which is not harmful to bone tissue. Cytotoxicity/viability tests reveal that direct mixing samples show higher cell proliferation than titration samples. Additionally, osteogenic differentiation essays show that all mineralized fibrils promote the osteogenic differentiation, but the effect is more pronounced when using samples prepared by direct mixing, and more notably when using the Tb3+‐doped mineralized fibrils. Based on these findings it is concluded that the new nanocomposite is an ideal candidate for bone regenerative therapy.
A methodology to simultaneously self‐assemble and mineralize type I collagen molecules by base‐acid neutralization allows the preparation of biomimetic collagen‐apatite fibers with varying mineralization extent, control of calcium phosphate polymorphism, and tailored luminescence by Tb3+ doping. The nanocomposites are cytocompatible and promote osteogenic differentiation of human mesenchymal stem cells, especially when using Tb3+‐doped materials.
Abstract
Human mitochondrial DNA (h-mtDNA) codes for 13 subunits of the oxidative phosphorylation pathway, the essential route that produces ATP. H-mtDNA transcription and replication depends on the ...transcription factor TFAM, which also maintains and compacts this genome. It is well-established that TFAM activates the mtDNA promoters LSP and HSP1 at the mtDNA control region where DNA regulatory elements cluster. Previous studies identified still uncharacterized, additional binding sites at the control region downstream from and slightly similar to LSP, namely sequences X and Y (Site-X and Site-Y) (Fisher et al., Cell 50, pp 247–258, 1987). Here, we explore TFAM binding at these two sites and compare them to LSP by multiple experimental and in silico methods. Our results show that TFAM binding is strongly modulated by the sequence-dependent properties of Site-X, Site-Y and LSP. The high binding versatility of Site-Y or the considerable stiffness of Site-X tune TFAM interactions. In addition, we show that increase in TFAM/DNA complex concentration induces multimerization, which at a very high concentration triggers disruption of preformed complexes. Therefore, our results suggest that mtDNA sequences induce non-uniform TFAM binding and, consequently, direct an uneven distribution of TFAM aggregation sites during the essential process of mtDNA compaction.
La escuela ha de fomentar el aprendizaje académico junto con una educación integral. La educación sexual debe promover el aprendizaje del conocimiento sexual, combinando las ideas previas del ...alumnado con una información objetiva y rigurosa de la sexualidad humana, y fomentar la adquisición de actitudes positivas. Es el profesorado quien tiene que impartir la educación sexual en los centros educativos, para lo cual es necesario que posea las competencias y la formación adecuada en esta temática. En este artículo se presenta un estudio cualitativo realizado con docentes de la comunidad de Castilla y León. Se entrevistó a 17 profesoras/es con el objetivo de indagar cómo abordan las/los docentes la educación sexual y las prácticas educativas que emplean para introducirla en el aula y en los centros educativos de la comunidad. Se aplicó un análisis temático de contenido. Los resultados y conclusiones obtenidas ponen de manifiesto carencias formativas del profesorado en relación con los conocimientos sobre la educación sexual y las acciones para abordarla en el aula. Por tanto, esta circunstancia enfatiza la necesidad de mejorar y regular la formación docente en materia de sexualidad para que estos profesionales sean capaces de impartirla en los centros educativos.
Candida albicans is a major cause of oropharyngeal, vulvovaginal and haematogenously disseminated candidiasis. Endocytosis of C. albicans hyphae by host cells is a prerequisite for tissue invasion. ...This internalization involves interactions between the fungal invasin Als3 and host E- or N-cadherin. Als3 shares some structural similarity with InlA, a major invasion protein of the bacterium Listeria monocytogenes. InlA mediates entry of L. monocytogenes into host cells through binding to E-cadherin. A role in internalization, for a non-classical stimulation of the clathrin-dependent endocytosis machinery, was recently highlighted. Based on the similarities between the C. albicans and L. monocytogenes invasion proteins, we studied the role of clathrin in the internalization of C. albicans. Using live-cell imaging and indirect immunofluorescence of epithelial cells infected with C. albicans, we observed that host E-cadherin, clathrin, dynamin and cortactin accumulated at sites of C. albicans internalization. Similarly, in endothelial cells, host N-cadherin, clathrin and cortactin accumulated at sites of fungal endocytosis. Furthermore, clathrin, dynamin or cortactin depletion strongly inhibited C. albicans internalization by epithelial cells. Finally, beads coated with Als3 were internalized in a clathrin-dependent manner. These data indicate that C. albicans, like L. monocytogenes, hijacks the clathrin-dependent endocytic machinery to invade host cells.
Innate immunity to Candida albicans depends upon the recognition of molecular patterns on the fungal cell wall. However, the masking of major components such as β-glucan seems to be a mechanism that ...fungi have evolved to avoid immune cell recognition through the dectin-1 receptor. Although the role of C. albicans mitogen-activated protein kinase (MAPK) pathways as virulence determinants has been established previously with animal models, the mechanism involved in this behavior is largely unknown. In this study we demonstrate that a disruption of the C. albicans extracellular signal-regulated kinase (ERK)-like 1 (CEK1)-mediated MAPK pathway causes enhanced cell wall β-glucan exposure, triggering immune responses more efficiently than the wild type, as measured by dectin-1-mediated specific binding and human dendritic cell (hDC)- and macrophage-mediated phagocytosis, killing, and activation of intracellular signaling pathways. At the molecular level, the disruption of CEK1 resulted in altered spleen tyrosine kinase (Syk), Raf-1, and ERK1/2 activations together with IκB degradation on hDCs and increased dectin-1-dependent activator protein 1 (AP-1) activation on transfected cells. In addition, concurring with these altered pathways, we detected increased reactive oxygen species production and cytokine secretion. In conclusion, the CEK1-mediated MAPK pathway is involved in β-glucan exposure in a fungal pathogen, hence influencing dectin-1-dependent immune cell recognition, thus establishing this fungal intracellular signaling route as a promising novel therapeutic target.
Abstract
Background
Patients with cancer have been shown to have a higher risk of clinical severity and mortality compared to non-cancer patients with COVID-19. Patients with hematologic malignancies ...typically are known to have higher levels of immunosuppression and may develop more severe respiratory viral infections than patients with solid tumors. Data on COVID-19 in patients with hematologic malignancies are limited. Here we characterize disease severity and mortality and evaluate potential prognostic factors for mortality.
Methods
In this population-based registry study, we collected de-identified data on clinical characteristics, treatment and outcomes in adult patients with hematologic malignancies and confirmed severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection within the Madrid region of Spain. Our case series included all patients admitted to 22 regional health service hospitals and 5 private healthcare centers between February 28 and May 25, 2020. The primary study outcome was all-cause mortality. We assessed the association between mortality and potential prognostic factors using Cox regression analyses adjusted for age, sex, comorbidities, hematologic malignancy and recent active cancer therapy.
Results
Of 833 patients reported, 697 were included in the analyses. Median age was 72 years (IQR 60–79), 413 (60%) patients were male and 479 (69%) and 218 (31%) had lymphoid and myeloid malignancies, respectively. Clinical severity of COVID-19 was severe/critical in 429 (62%) patients. At data cutoff, 230 (33%) patients had died. Age ≥ 60 years (hazard ratios 3.17–10.1 vs < 50 years), > 2 comorbidities (1.41 vs ≤ 2), acute myeloid leukemia (2.22 vs non-Hodgkin lymphoma) and active antineoplastic treatment with monoclonal antibodies (2·02) were associated with increased mortality; conventional chemotherapy showed borderline significance (1.50 vs no active therapy). Conversely, Ph-negative myeloproliferative neoplasms (0.33) and active treatment with hypomethylating agents (0.47) were associated with lower mortality. Overall, 574 (82%) patients received antiviral therapy. Mortality with severe/critical COVID-19 was higher with no therapy vs any antiviral combination therapy (2.20).
Conclusions
In this series of patients with hematologic malignancies and COVID-19, mortality was associated with higher age, more comorbidities, type of hematological malignancy and type of antineoplastic therapy. Further studies and long-term follow-up are required to validate these criteria for risk stratification.
Tyrosine kinase 2 (TYK2) is involved in type I interferon (IFN-I) signaling through IFN receptor 1 (IFNAR1). This signaling pathway is crucial in the early antiviral response and remains incompletely ...understood on B cells. Therefore, to understand the role of TYK2 in B cells, we studied these cells under homeostatic conditions and following in vitro activation using
Tyk2
-deficient (
Tyk2
−/−
) mice. Splenic B cell subpopulations were altered in
Tyk2
−/−
compared to wild type (WT) mice. Marginal zone (MZ) cells were decreased and aged B cells (ABC) were increased, whereas follicular (FO) cells remained unchanged. Likewise, there was an imbalance in transitional B cells in juvenile
Tyk2
−/−
mice. RNA sequencing analysis of adult MZ and FO cells isolated from
Tyk2
−/−
and WT mice in homeostasis revealed altered expression of IFN-I and Toll-like receptor 7 (TLR7) signaling pathway genes. Flow cytometry assays corroborated a lower expression of TLR7 in MZ B cells from
Tyk2
−/−
mice. Splenic B cell cultures showed reduced proliferation and differentiation responses after activation with TLR7 ligands in
Tyk2
−/−
compared to WT mice, with a similar response to lipopolysaccharide (LPS) or anti-CD40 + IL-4. IgM, IgG, IL-10 and IL-6 secretion was also decreased in
Tyk2
−/−
B cell cultures. This reduced response of the TLR7 pathway in
Tyk2
−/−
mice was partially restored by IFNα addition. In conclusion, there is a crosstalk between TYK2 and TLR7 mediated by an IFN-I feedback loop, which contributes to the establishment of MZ B cells and to B cell proliferation and differentiation.
(1) Background: For normo-nourished colorectal cancer patients, the need for immunonutrients after elective surgery is not known. (2) Methods: Multicenter, randomized, double-blind, phase III ...clinical trial comparing the postoperative diet with 200 mL oligomeric hyperproteic normocaloric (OHN; experimental arm) supplement vs. 200 mL immunonutritional (IN) (active comparator) supplement twice a day for five days in 151 normo-nourished adult colorectal-resection patients following the multimodal rehabilitation ERAS protocol. The proportions of patients with complications (primary outcome) and those who were readmitted, hospitalized for <7 days, had surgical site infections, or died due to surgical complications (secondary outcome) were compared between the two groups until postoperative day 30. Tolerance to both types of supplement and blood parameters was also assessed until day 5. (3) Results: Mean age was 69.2 and 84 (58.7%) were men. Complications were reported in 41 (28.7%) patients and the incidence did not differ between groups (18 (25%) vs. 23 (32.4%) patients with OHN and IN supplement, respectively; p = 0.328). No significant differences were found for the rest of the variables. (4) Conclusions: IN supplement may not be necessary for the postoperative recovery of colorectal cancer patients under the ERAS regimen and with normal nutritional status at the time of surgery.
Patients with ESRD undergoing peritoneal dialysis develop progressive peritoneal fibrosis, which may lead to technique failure. Recent data point to Th17-mediated inflammation as a key contributor in ...peritoneal damage. The leukocyte antigen CD69 modulates the setting and progression of autoimmune and inflammatory diseases by controlling the balance between Th17 and regulatory T cells (Tregs). However, the relevance of CD69 in tissue fibrosis remains largely unknown. Thus, we explored the role of CD69 in fibroproliferative responses using a mouse model of peritoneal fibrosis induced by dialysis fluid exposure under either normal or uremic status. We found that cd69
mice compared with wild-type (WT) mice showed enhanced fibrosis, mesothelial to mesenchymal transition, IL-17 production, and Th17 cell infiltration in response to dialysis fluid treatment. Uremia contributed partially to peritoneal inflammatory and fibrotic responses. Additionally, antibody-mediated CD69 blockade in WT mice mimicked the fibrotic response of cd69
mice. Finally, IL-17 blockade in cd69
mice decreased peritoneal fibrosis to the WT levels, and mixed bone marrow from cd69
and Rag2
c
mice transplanted into WT mice reproduced the severity of the response to dialysis fluid observed in cd69
mice, showing that CD69 exerts its regulatory function within the lymphocyte compartment. Overall, our results indicate that CD69 controls tissue fibrosis by regulating Th17-mediated inflammation.
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