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Despite extensive studies into severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the effect of maternal infection on the neonate is unclear. To investigate this, we characterized the immunology of neonates born to mothers with confirmed SARS-CoV-2 infection during pregnancy. Here we show that maternal SARS-CoV-2 infection affects the neonatal immune system. Despite similar proportions of B cells, CD4+ T cells and CD8+ T cells, increased percentages of natural killer cells, Vδ2+ γδ T cells and regulatory T cells were detected in neonates born to mothers with recent or ongoing infection compared with those born to recovered or uninfected mothers. Increased plasma cytokine levels were also evident in neonates and mothers within the recent or ongoing infection group. Cytokine functionality was enhanced in neonates born to SARS-CoV-2-exposed mothers, compared to those born to uninfected mothers. In most neonates, this immune imprinting was nonspecific, suggesting vertical transmission of SARS-CoV-2 is limited, a finding supported by a lack of SARS-CoV-2-specific IgM in neonates despite maternal IgG transfer.
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COVID-19/inmunología , Enfermedades del Recién Nacido/inmunología , Transmisión Vertical de Enfermedad Infecciosa , Complicaciones Infecciosas del Embarazo/inmunología , SARS-CoV-2/inmunología , Adulto , Anticuerpos Antivirales/inmunología , COVID-19/diagnóstico , COVID-19/virología , Citocinas/sangre , Citocinas/inmunología , Citocinas/metabolismo , Femenino , Humanos , Inmunidad Innata/inmunología , Inmunoglobulina G/inmunología , Recién Nacido , Enfermedades del Recién Nacido/diagnóstico , Enfermedades del Recién Nacido/virología , Células Asesinas Naturales/inmunología , Embarazo , Complicaciones Infecciosas del Embarazo/virología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , SARS-CoV-2/fisiología , Linfocitos T/inmunología , Linfocitos T/metabolismo , Linfocitos T Reguladores/inmunologíaRESUMEN
A hallmark of autoimmunity in murine models of lupus is the formation of germinal centers (GCs) in lymphoid tissues where self-reactive B cells expand and differentiate. In the host response to foreign antigens, follicular dendritic cells (FDCs) maintain GCs through the uptake and cycling of complement-opsonized immune complexes. Here, we examined whether FDCs retain self-antigens and the impact of this process in autoantibody secretion in lupus. We found that FDCs took up and retained self-immune complexes composed of ribonucleotide proteins, autoantibody, and complement. This uptake, mediated through CD21, triggered endosomal TLR7 and led to the secretion of interferon (IFN) α via an IRF5-dependent pathway. Blocking of FDC secretion of IFN-α restored B cell tolerance and reduced the amount of GCs and pathogenic autoantibody. Thus, FDCs are a critical source of the IFN-α driving autoimmunity in this lupus model. This pathway is conserved in humans, suggesting that it may be a viable therapeutic target in systemic lupus erythematosus.
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Autoinmunidad/inmunología , Linfocitos B/inmunología , Células Dendríticas Foliculares/inmunología , Lupus Eritematoso Sistémico/inmunología , Animales , Autoantígenos/inmunología , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Femenino , Citometría de Flujo , Perfilación de la Expresión Génica , Humanos , Inmunohistoquímica , Interferón-alfa/biosíntesis , Interferón-alfa/inmunología , Ligandos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microscopía Confocal , Reacción en Cadena de la Polimerasa , Receptor Toll-Like 7/inmunología , TranscriptomaRESUMEN
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Whereas pathogen-specific T and B cells are a primary focus of interest during infectious disease, we have used COVID-19 to ask whether their emergence comes at a cost of broader B cell and T cell repertoire disruption. We applied a genomic DNA-based approach to concurrently study the immunoglobulin-heavy (IGH) and T cell receptor (TCR) ß and δ chain loci of 95 individuals. Our approach detected anticipated repertoire focusing for the IGH repertoire, including expansions of clusters of related sequences temporally aligned with SARS-CoV-2-specific seroconversion, and enrichment of some shared SARS-CoV-2-associated sequences. No significant age-related or disease severity-related deficiencies were noted for the IGH repertoire. By contrast, whereas focusing occurred at the TCRß and TCRδ loci, including some TCRß sequence-sharing, disruptive repertoire narrowing was almost entirely limited to many patients aged older than 50 y. By temporarily reducing T cell diversity and by risking expansions of nonbeneficial T cells, these traits may constitute an age-related risk factor for COVID-19, including a vulnerability to new variants for which T cells may provide key protection.
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Inmunidad Adaptativa , COVID-19 , Cadenas Pesadas de Inmunoglobulina , Receptores de Antígenos de Linfocitos T alfa-beta , Receptores de Antígenos de Linfocitos T , SARS-CoV-2 , Inmunidad Adaptativa/genética , Anciano , Linfocitos B/inmunología , COVID-19/genética , COVID-19/inmunología , Sitios Genéticos , Humanos , Cadenas Pesadas de Inmunoglobulina/genética , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T alfa-beta/genética , SARS-CoV-2/inmunología , Seroconversión , Linfocitos T/inmunologíaRESUMEN
Cervical cancer is the primary cause of mortality among women in developing countries. Preventing cervical cancer is partially possible through early vaccination against the human papillomavirus, the most common cause of the disease. Nevertheless, it is imperative to understand the genetics of the disease progression to develop new therapeutic strategies. The present study aims to identify potential genes and associated pathways associated with cervical squamous cell carcinoma progression. We used an integrative approach by combining differential expression analysis, network biology, and functional enrichment analysis with survival analysis. In the present study, differential expression analysis of the microarray-based gene expression profiles of cervical cancer resulted in identifying a total of 544 significantly differentially expressed genes (DEGs). Further, centrality and network vulnerability analysis of the protein-protein interaction network (PPIN) and not well documented in cervical cancer, resulted in seven proteins (FN1, MCM5, TRIP13, KIF11, TTK, CDC45, and BUB1B), in which four proteins were vulnerable. These genes are mostly enriched in biological processes of cell division, mitotic nuclear division, cell cycle checkpoint, and cell proliferation in gene ontology analysis. The KEGG pathway enrichment analysis of the proteins lists them as mainly associated with the cell cycle. In the survival analysis, it was found that the genes MCM5, FN1, KIF11, and CDC45 were statistically significant prognostic factors for cervical cancer. The outcome of the current study identifies and explores the key role of the candidate genes involved in the progression of cervical cancer.
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Carcinoma de Células Escamosas , Neoplasias del Cuello Uterino , Humanos , Femenino , Perfilación de la Expresión Génica/métodos , Neoplasias del Cuello Uterino/genética , Biología Computacional/métodos , Transcriptoma , Carcinoma de Células Escamosas/genética , ATPasas Asociadas con Actividades Celulares Diversas/genética , Proteínas de Ciclo CelularRESUMEN
The role of boron-doped thiazoles as a Lewis acid catalyst in [4+2] cycloaddition reaction between 1,3-butadiene and acrolein has been addressed. Three different organic heterocycles were designed to study their catalytic activity. It has been observed that these heterocycles efficiently work as catalysts than the well-known Lewis acid BF3. All the reactions follow the normal electron demand process and are exothermic. Different conceptual DFT-based reactivity descriptors and electronic structure principles such as maximum hardness and minimum electrophilicity lend additional support to the feasibility of the reaction mechanism. The reaction force (RF), reaction electronic flux (REF), and its different components exhibit a detailed electronic activity throughout the reaction.
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Systemic lupus erythematosus (SLE) is an incurable autoimmune disease characterized by autoantibody deposition in tissues such as kidney, skin and lungs. Notably, up to 75% of patients with SLE experience neuropsychiatric symptoms that range from anxiety, depression and cognitive impairment to seizures and, in rare cases, psychosis-collectively this is referred to as central nervous system (CNS) lupus. In some cases, certain autoantibodies, such as anti-NMDAR or anti-phospholipid antibodies, promote CNS lupus. However, in most patients, the mechanisms that underlie these symptoms are unknown. CNS lupus typically presents at lupus diagnosis or within the first year, suggesting that early factors contributing to peripheral autoimmunity may promote CNS lupus symptoms. Here we report behavioural phenotypes and synapse loss in lupus-prone mice that are prevented by blocking type I interferon (IFN) signalling. Furthermore, we show that type I IFN stimulates microglia to become reactive and engulf neuronal and synaptic material in lupus-prone mice. These findings and our observation of increased type I IFN signalling in post-mortem hippocampal brain sections from patients with SLE may instruct the evaluation of ongoing clinical trials of anifrolumab, a type I IFN-receptor antagonist. Moreover, identification of IFN-driven microglia-dependent synapse loss, along with microglia transcriptome data, connects CNS lupus with other CNS diseases and provides an explanation for the neurological symptoms observed in some patients with SLE.
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Interferón Tipo I/inmunología , Vasculitis por Lupus del Sistema Nervioso Central/inmunología , Vasculitis por Lupus del Sistema Nervioso Central/patología , Microglía/inmunología , Microglía/patología , Sinapsis/patología , Animales , Anticuerpos Monoclonales/uso terapéutico , Anticuerpos Monoclonales Humanizados , Conducta Animal , Modelos Animales de Enfermedad , Femenino , Hipocampo/metabolismo , Hipocampo/patología , Humanos , Interferón Tipo I/antagonistas & inhibidores , Vasculitis por Lupus del Sistema Nervioso Central/psicología , Masculino , Ratones , Microglía/metabolismo , Fenotipo , Transducción de Señal , Sinapsis/inmunología , TranscriptomaRESUMEN
Ecosystem services (ES) are becoming a burgeoning topic presently playing a crucial role in sustaining human well-being, socioeconomic growth, and addressing environmental management and sustainability. The purpose of our review was to overview research trends of the forest ecosystem services (FES) in eastern India and the research methodologies adopted to evaluate them. To systematically study the FES literature, 127 articles pertaining to the term FES during the period 1991 to 2021 were reviewed through a quantitative analysis. The analytical outcome emphasized (1) the research aspects of FES and its types along with regional distribution, (2) the scenario of FES in eastern India with respect to other ES and India, (3) the quantitative trend of FES research over 30 years period, (4) the employed methodological approaches, and (5) the existing research gaps and prospects. Our findings suggest that the publication numbers are quite low in eastern India, as only 5 peer-reviewed articles were found on FES. The result also indicated that the majority of studies primarily focused on provisioning services (85.03%) and the survey/interview method gained more popularity as a primary data source. Most of the earlier studies employed basic assessments like product values or individual income. We also discussed the advantages as well as limitations of the employed methodologies. These findings further highlight the significance of valuing various FES collectively rather than individually and contribute to providing pertinent information for the FES literature scenario, which may help to strengthen forest management as well.
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Conservación de los Recursos Naturales , Ecosistema , Humanos , Monitoreo del Ambiente , Bosques , IndiaRESUMEN
Boron dipyrromethene, commonly known as BODIPY, based metal-organic macrocycles (MOCs) and metal-organic frameworks (MOFs) represent an interesting part of materials due to their versatile tunability of structure and functionality as well as significant physicochemical properties, thus broadening their applications in various scientific domains, especially in biomedical sciences. With increasing concern over the efficacy of cancer drugs versus quality of patient's life dilemma, scientists have been trying to fabricate novel comprehensive therapeutic strategies along with the discovery of novel safer drugs where research with BODIPY metal complexes has shown vital advancements. In this review, we have exclusively examined the articles involving studies related to light harvesting and photophysical properties of BODIPY based MOCs and MOFs, synthesized through self-assembly process, with a special focus on biomolecular interaction and its importance in anti-cancer drug research. In the end, we also emphasized the possible practical challenges involved during the synthetic process, based on our experience on dealing with BODIPY molecules and steps to overcome them along with their future potentials. This review will significantly help our fellow research groups, especially the budding researchers, to quickly and comprehensively get the near to wholesome picture of BODIPY based MOCs and MOFs and their present status in anti-cancer drug discovery.
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Using 250 neutron star merger simulations with microphysics, we explore for the first time the role of nuclear incompressibility in the prompt collapse threshold for binaries with different mass ratios. We demonstrate that observations of prompt collapse thresholds, either from binaries with two different mass ratios or with one mass ratio but combined with the knowledge of the maximum neutron star mass or compactness, will constrain the incompressibility at the maximum neutron star density K_{max} to within tens of percent. This otherwise inaccessible measure of K_{max} can potentially reveal the presence of hyperons or quarks inside neutron stars.
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The unexplored 'actor' behavior of redox-active bis(aldimine) congener, p-phenylene-bis(picoline)aldimine (L1), towards dioxygen activation and subsequent functionalization of its backbone was demonstrated on coordination with {Ru(acac)2 } (acac= acetylacetonate). Reaction under aerobic condition led to the one-pot generation of dinuclear complexes with unperturbed L1, imino-carboxamido (L2- ), and bis(carboxamido) (L32- )-bridged isovalent {RuII (µ-L1)RuII }, 1/ {RuIII (µ-L32- )RuIII }, 3 and mixed-valent {RuII (µ-L2- )RuIII }, 2. Authentication of the complexes along with the redox non-innocence behavior of their bridge have been validated through structure, spectroelectrochemistry and DFT calculations. Kinetic and isotope labelling experiments together with DFT analyzed transition states justified the consideration of redox shuttling at metal/L1 interface for 3 O2 activation despite of the closed shell configuration of 1 (S=0) to give carboxamido derived 2/3.
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Compuestos Organometálicos , Rutenio , Ligandos , Rutenio/química , Oxígeno , Compuestos Organometálicos/química , Electroquímica , Oxidación-ReducciónRESUMEN
BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic was an unforeseen calamity. Sudden disruption of nonemergency services led to disruption of treatment across all specialties. Oncology revolves around the tenet of timely detection and treatment. Disruption of any sort will jeopardize cure rates. The time interval between coronavirus infection and cancer surgery is variable and needs to be tailored to avoid the progression of the disease. METHODS: We analyzed the impact of preoperative coronavirus disease 2019 (COVID-19) infection on the planned cancer surgery, delay, disease progression, and change of intent of treatment from April 1 to May 31, 2021 at a tertiary care center. All preoperative positive patients were retested after 2 weeks and were considered for surgery if the repeat test was negative and asymptomatic. FINDINGS: Our study included 432 preoperative patients of which 91 (21%) were COVID-19 positive. Amongst this cohort, 76% were operated and the morbidity and mortality were comparable to the COVID-19 negative cohort. Around 10% of the COVID-19 positive were lost to follow up and 10% had disease progression and were deemed palliative INTERPRETATION: SARS-CoV-2 infection has adversely impacted cancer care and a 2-week waiting period postinfection seems to be a safe interval in asymptomatic individuals to consider radical cancer surgery.
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COVID-19/epidemiología , Neoplasias/cirugía , SARS-CoV-2 , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , India/epidemiología , Masculino , Persona de Mediana Edad , Neoplasias/mortalidad , Estudios Retrospectivos , Centros de Atención Terciaria , Adulto JovenRESUMEN
Recent advances in Graph Neural Networks (GNNs) have transformed the space of molecular and catalyst discovery. Despite the fact that the underlying physics across these domains remain the same, most prior work has focused on building domain-specific models either in small molecules or in materials. However, building large datasets across all domains is computationally expensive; therefore, the use of transfer learning (TL) to generalize to different domains is a promising but under-explored approach to this problem. To evaluate this hypothesis, we use a model that is pretrained on the Open Catalyst Dataset (OC20), and we study the model's behavior when fine-tuned for a set of different datasets and tasks. This includes MD17, the *CO adsorbate dataset, and OC20 across different tasks. Through extensive TL experiments, we demonstrate that the initial layers of GNNs learn a more basic representation that is consistent across domains, whereas the final layers learn more task-specific features. Moreover, these well-known strategies show significant improvement over the non-pretrained models for in-domain tasks with improvements of 53% and 17% for the *CO dataset and across the Open Catalyst Project (OCP) task, respectively. TL approaches result in up to 4× speedup in model training depending on the target data and task. However, these do not perform well for the MD17 dataset, resulting in worse performance than the non-pretrained model for few molecules. Based on these observations, we propose transfer learning using attentions across atomic systems with graph Neural Networks (TAAG), an attention-based approach that adapts to prioritize and transfer important features from the interaction layers of GNNs. The proposed method outperforms the best TL approach for out-of-domain datasets, such as MD17, and gives a mean improvement of 6% over a model trained from scratch.
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Aprendizaje Automático , Redes Neurales de la ComputaciónRESUMEN
Spin states of iron often direct the selectivity in oxidation catalysis by iron complexes using hydrogen peroxide (H2O2) on an oxidant. While low-spin iron(III) hydroperoxides display stereoselective C-H bond hydroxylation, the reactions are nonstereoselective with high-spin iron(II) catalysts. The catalytic studies with a series of high-spin iron(II) complexes of N4 ligands with H2O2 and Sc3+ reported here reveal that the Lewis acid promotes catalytic C-H bond hydroxylation with high chemo- and stereoselectivity. This reactivity pattern is observed with iron(II) complexes containing two cis-labile sites. The enhanced selectivity for C-H bond hydroxylation catalyzed by the high-spin iron(II) complexes in the presence of Sc3+ parallels that of the low-spin iron catalysts. Furthermore, the introduction of multimetal centers enhances the activity and selectivity of the iron catalyst. The study provides insights into the development of peroxide-dependent bioinspired catalysts for the selective oxygenation of C-H bonds without the restriction of using iron complexes of strong-field ligands.
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BACKGROUND: Cellular reprogramming in response to environmental stress involves alteration of gene expression, changes in the protein and metabolite profile for ensuring better stress management in plants. Similar to other plant species originating in tropical and sub-tropical areas, indica rice is highly sensitive to low temperature that adversely affects its growth and grain productivity. Substantial work has been done to understand cold induced changes in gene expression in rice plants. However, adequate information is not available for early gene expression, especially in indica variety. Therefore, a transcriptome profile was generated for cold shock treated seedlings of IR64 variety to identify early responsive genes. RESULTS: The functional annotation of early DEGs shows enrichment of genes involved in altered membrane rigidity and electrolytic leakage, the onset of calcium signaling, ROS generation and activation of stress responsive transcription factors in IR64. Gene regulatory network suggests that cold shock induced Ca2+ signaling activates DREB/CBF pathway and other groups of transcription factors such as MYB, NAC and ZFP; for activating various cold-responsive genes. The analysis also indicates that cold induced signaling proteins like RLKs, RLCKs, CDPKs and MAPKK and ROS signaling proteins. Further, several late-embryogenesis-abundant (LEA), dehydrins and low temperature-induced-genes were upregulated under early cold shock condition, indicating the onset of water-deficit conditions. Expression profiling in different high yielding cultivars shows high expression of cold-responsive genes in Heera and CB1 indica varieties. These varieties show low levels of cold induced ROS production, electrolytic leakage and high germination rate post-cold stress, compared to IR36 and IR64. Collectively, these results suggest that these varieties may have improved adaptability to cold stress. CONCLUSIONS: The results of this study provide insights about early responsive events in Oryza sativa l.ssp. indica cv IR64 in response to cold stress. Our data shows the onset of cold response is associated with upregulation of stress responsive TFs, hydrophilic proteins and signaling molecules, whereas, the genes coding for cellular biosynthetic enzymes, cell cycle control and growth-related TFs are downregulated. This study reports that the generation of ROS is integral to the early response to trigger the ROS mediated signaling events during later stages.
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Perfilación de la Expresión Génica/métodos , Redes Reguladoras de Genes , Oryza/clasificación , Respuesta al Choque por Frío , Regulación de la Expresión Génica de las Plantas , Germinación , Secuenciación de Nucleótidos de Alto Rendimiento , Anotación de Secuencia Molecular , Oryza/fisiología , Filogenia , Proteínas de Plantas/genética , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Phytophthora ramorum is a destructive pathogen that causes sudden oak death disease. The genome sequence of P. ramorum isolate Pr102 was previously produced, using Sanger reads, and contained 12 Mb of gaps. However, isolate Pr102 had shown reduced aggressiveness and genome abnormalities. In order to produce an improved genome assembly for P. ramorum, we performed long-read sequencing of highly aggressive P. ramorum isolate CDFA1418886 (abbreviated as ND886). We generated a 60.5-Mb assembly of the ND886 genome using the Pacific Biosciences (PacBio) sequencing platform. The assembly includes 302 primary contigs (60.2 Mb) and nine unplaced contigs (265 kb). Additionally, we found a 'highly repetitive' component from the PacBio unassembled unmapped reads containing tandem repeats that are not part of the 60.5-Mb genome. The overall repeat content in the primary assembly was much higher than the Pr102 Sanger version (48 versus 29%), indicating that the long reads have captured repetitive regions effectively. The 302 primary contigs were phased into 345 haplotype blocks and 222,892 phased variants, of which the longest phased block was 1,513,201 bp with 7,265 phased variants. The improved phased assembly facilitated identification of 21 and 25 Crinkler effectors and 393 and 394 RXLR effector genes from two haplotypes. Of these, 24 and 25 RXLR effectors were newly predicted from haplotypes A and B, respectively. In addition, seven new paralogs of effector Avh207 were found in contig 54, not reported earlier. Comparison of the ND886 assembly with Pr102 V1 assembly suggests that several repeat-rich smaller scaffolds within the Pr102 V1 assembly were possibly misassembled; these regions are fully encompassed now in ND886 contigs. Our analysis further reveals that Pr102 is a heterokaryon with multiple nuclear types in the sequences corresponding to contig 10 of ND886 assembly.
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Variaciones en el Número de Copia de ADN , Genoma de Protozoos , Phytophthora , Polimorfismo Genético , Genoma de Protozoos/genética , Haplotipos , Phytophthora/genéticaRESUMEN
The synthesis of a SIPr [1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene] derived Kekulé diradicaloid with a tetrafluorophenylene spacer (3) has been described. Two synthetic routes have been reported to access 3. The cleavage of C-F bond of C6 F6 by SIPr in the presence of BF3 led to double C-F activated compound with two tetrafluoro borate counter anions (2), which upon reduction by lithium metal afforded 3. Alternatively, 3 can be directly accessed in one step by reacting SIPr with C6 F6 in presence of Mg metal. Compounds 2 and 3 were well characterized spectroscopically and by single-crystal X-ray diffraction studies. Experimental and computational studies support the cumulenic closed-shell singlet state of 3 with a singlet-triplet energy gap (ΔES-T ) of 23.7â kcal mol-1 .
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Unlike T cells that recognize digested peptides, B cells recognize their cognate antigen in its native form. The B cell receptor used in recognition can also be secreted to bind to antigens and initiate multiple effector functions such as phagocytosis, complement activation, or neutralization of receptors. While B cells can interact with soluble antigens, it is now clear that the presentation of membrane-bound antigen plays a crucial role in B cell activation, and in particular during affinity-maturation, the process during which high-affinity B cells are selected. In this review we discuss how native antigen is presented to B cells and its impact at several stages of B cell responses.
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Presentación de Antígeno , Células Presentadoras de Antígenos/inmunología , Linfocitos B/inmunología , Activación de Linfocitos , Receptores de Antígenos de Linfocitos B/metabolismo , Animales , Afinidad de Anticuerpos , Antígenos/inmunología , Selección Clonal Mediada por Antígenos , Activación de Complemento , Humanos , FagocitosisRESUMEN
The oxomanganese(IV) complex [(dpaq)MnIV(O)]+-Mn+ (1-Mn+, Mn+ = redox-inactive metal ion, H-dpaq = 2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-ylacetamide), generated in the reaction of the precursor hydroxomanganese(III) complex 1 with iodosylbenzene (PhIO) in the presence of redox-inactive metal triflates, has recently been reported. Herein the generation of the same oxomanganese(IV) species from 1 using various combinations of protic acids and oxidants at 293 K is reported. The reaction of 1 with triflic acid and the one-electron-oxidizing agent [RuIII(bpy)3]3+ leads to the formation of the oxomanganese(IV) complex. The putative species has been identified as a mononuclear high-spin (S = 3/2) nonheme oxomanganese(IV) complex (1-O) on the basis of mass spectrometry, Raman spectroscopy, EPR spectroscopy, and DFT studies. The optical absorption spectrum is well reproduced by theoretical calculations on an S = 3/2 ground spin state of the complex. Isotope labeling studies confirm that the oxygen atom in the oxomanganese(IV) complex originates from the MnIII-OH precursor and not from water. A mechanistic investigation reveals an initial protonation step forming the MnIII-OH2 complex, which then undergoes one-electron oxidation and subsequent deprotonations to form the oxomanganese(IV) transient, avoiding the requirements of either oxo-transfer agents or redox-inactive metal ions. The MnIV-oxo complex cleaves the C-H bonds of xanthene (k2 = 5.5 M-1 s-1), 9,10-DHA (k2 = 3.9 M-1 s-1), 1,4-CHD (k2 = 0.25 M-1 s-1), and fluorene (k2 = 0.11 M-1 s-1) at 293 K. The electrophilic character of the nonheme MnIV-oxo complex is demonstrated by a large negative ρ value of 2.5 in the oxidation of para-substituted thioanisoles. The complex emerges as the "most reactive" among the existing MnIV/V-oxo complexes bearing anionic ligands.