Inhibitory Phenotype of HBV-Specific CD4⁺ T-Cells Is Characterized by High PD-1 Expression but Absent Coregulation of Multiple Inhibitory Molecules

Background: T-cell exhaustion seems to play a critical role in CD8(+) T-cell dysfunction during chronic viral infections. However, up to now little is known about the mechanisms underlying CD4(+) T-cell dysfunction during chronic hepatitis B virus (CHB) infection and the role of inhibitory molecules such as programmed death 1 (PD-1) for CD4(+) T-cell failure. Methods: The expression of multiple inhibitory molecules such as PD-1, CTLA-4, TIM-3, CD244, KLRG1 and markers defining the grade of T-cell differentiation as CCR7, CD45RA, CD57 and CD127 were analyzed on virus-specific CD4(+) T-cells from peripheral blood using a newly established DRB1*01-restricted MHC class II Tetramer. Effects of in vitro PD-L1/2 blockade were defined by investigating changes in CD4(+) T-cell proliferation and cytokine production. Results: CD4(+) T-cell responses during chronic HBV infection was characterized by reduced Tetramer(+)CD4(+) T-cell frequencies, effector memory phenotype, sustained PD-1 but low levels of CTLA-4, TIM-3, KLRG1 and CD244 expression. PD-1 blockade revealed individualized patterns of in vitro responsiveness with partly increased IFN-gamma, IL-2 and TNF-alpha secretion as well as enhanced CD4(+) T-cell expansion almost in treated patients with viral control. Conclusion: HBV-specific CD4(+) T-cells are reliably detectable during different courses of HBV infection by MHC class II Tetramer technology. CD4(+) T-cell dysfunction during chronic HBV is basically linked to strong PD-1 upregulation but absent coregulation of multiple inhibitory receptors. PD-L1/2 neutralization partly leads to enhanced CD4(+) T-cell functionality with heterogeneous patterns of CD4(+) T-cell rejunivation

1,7,9,10-Tetrasubstituted PMIs Accessible through Decarboxylative Bromination: Synthesis, Characterization, Photophysical Studies, and Hydrogen Evolution Catalysis

In this work, we present a new synthetic strategy for fourfold-substituted perylene monoimides via tetrabrominated perylene monoanhydrides. X-ray diffraction analysis unveiled the intramolecular stacking orientation between the substituents and semicircular packing behavior. We observed the remarkable influence of the substituent on the longevity and nature of the excited state upon visible light excitation. In the presence of poly(dehydroalanine)-graft-poly(ethylene glycol) graft copolymers as solubilizing template, the chromophores are capable of sensitizing [Mo3S13]2− clusters in aqueous solution for stable visible light driven hydrogen evolution over three days. © 2020 The Authors. Chemistry - A European Journal published by Wiley-VCH Gmb

Antibiotics prescribing practices in oral implantology among jordanian dentists. A cross sectional, observational study

<p>Abstract</p> <p>Background</p> <p>In oral implantology, there is no consensus on the most appropriate regimen for antibiotics prescribing, the decision to prescribe antibiotic is usually based on procedure, patient and clinician related factors. The aim of this study was to investigate the rationale of antibiotic prescribing among Jordanian clinicians who practice oral implantology.</p> <p>Findings</p> <p>The target sample for the study was the 250 Jordan Dental Implant Group members. A five page questionnaire contained 41 questions, both closed and open questions were used to collect data. Statistical analysis was performed using SPSS Windows 16.0 (SPSS Inc., Chicago, IL, USA). Descriptive statistics were generated.</p> <p>The response rate was (70.4%) 176/250. Mean age was 37.2 yrs, 49.4% always prescribe antibiotics mainly oral amoxicillin and amoxicillin with clavulinic acid. Antibiotics prescribing increased with flap raising, multiple implants and sinus or bone augmentation. Patient medical condition, periodontitis and oral hygiene were the most important clinical factors in antibiotic prescribing, non-clinical factors were; reading scientific materials, courses and lectures, knowledge gained during training, and the effectiveness and previous experience with the drug.</p> <p>Conclusions</p> <p>Wide variations in antibiotics types, routes, dose and duration of administration were found. Recommendations on antibiotic prescribing are needed to prevent antibiotic overprescribing and misuse.</p

Cell cycle-independent phospho-regulation of Fkh2 during hyphal growth regulates Candida albicans pathogenesis.

The opportunistic human fungal pathogen, Candida albicans, undergoes morphological and transcriptional adaptation in the switch from commensalism to pathogenicity. Although previous gene-knockout studies have identified many factors involved in this transformation, it remains unclear how these factors are regulated to coordinate the switch. Investigating morphogenetic control by post-translational phosphorylation has generated important regulatory insights into this process, especially focusing on coordinated control by the cyclin-dependent kinase Cdc28. Here we have identified the Fkh2 transcription factor as a regulatory target of both Cdc28 and the cell wall biosynthesis kinase Cbk1, in a role distinct from its conserved function in cell cycle progression. In stationary phase yeast cells 2D gel electrophoresis shows that there is a diverse pool of Fkh2 phospho-isoforms. For a short window on hyphal induction, far before START in the cell cycle, the phosphorylation profile is transformed before reverting to the yeast profile. This transformation does not occur when stationary phase cells are reinoculated into fresh medium supporting yeast growth. Mass spectrometry and mutational analyses identified residues phosphorylated by Cdc28 and Cbk1. Substitution of these residues with non-phosphorylatable alanine altered the yeast phosphorylation profile and abrogated the characteristic transformation to the hyphal profile. Transcript profiling of the phosphorylation site mutant revealed that the hyphal phosphorylation profile is required for the expression of genes involved in pathogenesis, host interaction and biofilm formation. We confirmed that these changes in gene expression resulted in corresponding defects in pathogenic processes. Furthermore, we identified that Fkh2 interacts with the chromatin modifier Pob3 in a phosphorylation-dependent manner, thereby providing a possible mechanism by which the phosphorylation of Fkh2 regulates its specificity. Thus, we have discovered a novel cell cycle-independent phospho-regulatory event that subverts a key component of the cell cycle machinery to a role in the switch from commensalism to pathogenicity

Dysfunctional CD8(+) T cells in hepatitis B and C are characterized by a lack of antigen-specific T-bet induction

The transcription factor T-bet regulates the production of interferon-γ and cytotoxic molecules in effector CD8 T cells, and its expression correlates with improved control of chronic viral infections. However, the role of T-bet in infections with differential outcome remains poorly defined. Here, we report that high expression of T-bet in virus-specific CD8 T cells during acute hepatitis B virus (HBV) and hepatitis C virus (HCV) infection was associated with spontaneous resolution, whereas T-bet deficiency was more characteristic of chronic evolving infection. T-bet strongly correlated with interferon-γ production and proliferation of virus-specific CD8 T cells, and its induction by antigen and IL-2 stimulation partially restored functionality in previously dysfunctional T-bet–deficient CD8 T cells. However, restoration of a strong interferon-γ response required additional stimulation with IL-12, which selectively induced the phosphorylation of STAT4 in T-bet(+) CD8 T cells. The observation that T-bet expression rendered CD8 T cells responsive to IL-12 suggests a stepwise mechanism of T cell activation in which T-bet facilitates the recruitment of additional transcription factors in the presence of key cytokines. These findings support a critical role of T-bet for viral clearance and suggest T-bet deficiency as an important mechanism behind chronic infection

Stochastic thermodynamics of self-oscillations : the electron shuttle

Self-oscillation is a phenomenon studied across many scientific disciplines, including the engineering of efficient heat engines and electric generators. We investigate the single electron shuttle, a model nano-scale system that exhibits a spontaneous transition towards self-oscillation, from a thermodynamic perspective. We analyse the model at three different levels of description: The fully stochastic level based on Fokker-Planck and Langevin equations, the mean-field (MF) level, and a perturbative solution to the Fokker-Planck equation that works particularly well for small oscillation amplitudes. We provide consistent derivations of the laws of thermodynamics for this model system at each of these levels. At the MF level, an abrupt transition to self-oscillation arises from a Hopf bifurcation of the deterministic equations of motion. At the stochastic level, this transition is smeared out by noise, but vestiges of the bifurcation remain visible in the stationary probability density. At all levels of description, the transition towards self-oscillation is reflected in thermodynamic quantities such as heat flow, work and entropy production rate. Our analysis provides a comprehensive picture of a nano-scale self-oscillating system, with stochastic and deterministic models linked by a unifying thermodynamic perspective