135 research outputs found
<i>N</i>-derivatives of <i>peri</i>-substituted dichalcogenide[FeFe]-hydrogenase mimics:towards photocatalytic dyads for hydrogen production
Synthetic strategies towards molecular dyads based on peri-substituted dichalcogenide (S,Se) [FeFe]-hydrogenase synthetic mimics covalently linked to a ZnTPP photosensitizer are described. Dithiolate and diselenolate model systems 2–5 are prepared through condensation of 2-naphthaldehydes with p-methoxyaniline, reduction of the resulting Schiff base and oxidative insertion of Fe2(CO)6 into the dichalcogen bond of the imine or amine. Diselenolate-based [FeFe] complexes (imine 3 and amine 5) are more efficient in electrocatalysis of proton reduction than their sulfur analogues 2 and 4 with increasing concentrations of pTsOH. Molecular dyad 1 containing a peri-substituted naphthalene dithiolate Fe2(CO)6 cluster covalently linked via an amine to ZnTPP is prepared through sequential zinc insertion into the porphyrin followed by iron insertion into the disulfide bon
Experience with telemedicine among rheumatology clinicians during the COVID-19 pandemic: an international survey
Objective: The aim was to assess rheumatology clinicians' perceptions of telemedicine and their experiences before and during the coronavirus disease 2019 (COVID-19) pandemic. Methods: We conducted a cross-sectional online survey and collected responses from rheumatology clinicians worldwide, between November 2020 and February 2021, regarding use and perceptions of telemedicine in rheumatology. We summarized data with descriptive statistics and qualitative analysis for free-text responses. Results: The survey was completed by 349 rheumatology clinicians from 49 countries; 59% were female and about two-thirds were in the 30-50 years age group. Academic affiliations were held by 55% of participants, and 44% were from North America. Before the pandemic, 24% of participants had experience with telemedicine, whereas about three-quarters used telemedicine for the first time during the pandemic. Overall, 56% thought they provided less adequate care with telemedicine. More than half of clinicians felt that telemedicine was adequate for evaluating crystalline arthritis, inflammatory arthritis and lupus flares. Telemedicine was felt to be inadequate for flares of myositis, vasculitis and scleroderma. Technical problems were reported in 29% of telemedicine encounters and were most commonly related to patient-encountered difficulties. Conclusion: Most rheumatology clinicians used telemedicine for the first time during the pandemic. The quality of care provided was thought to be inferior to that provided in person for specific clinical situations. Additional efforts are needed to address barriers to effective telemedicine, such as patient-related technology issues, challenges with building rapport and performing a physical examination, and to define the appropriate scope of clinical scenarios conducive to telemedicine
Horizontally acquired AT-rich genes in Escherichia coli cause toxicity by sequestering RNA polymerase
Horizontal gene transfer permits rapid dissemination of genetic elements between individuals in bacterial populations.
Transmitted DNA sequences may encode favourable traits. However, if the acquired DNA has an atypical base
composition, it can reduce host fitness. Consequently, bacteria have evolved strategies to minimize the harmful effects of
foreign genes. Most notably, xenogeneic silencing proteins bind incoming DNA that has a higher AT content than the host
genome. An enduring question has been why such sequences are deleterious. Here, we showed that the toxicity of AT-rich
DNA in Escherichia coli frequently results from constitutive transcription initiation within the coding regions of genes. Left
unchecked, this causes titration of RNA polymerase and a global downshift in host gene expression. Accordingly, a
mutation in RNA polymerase that diminished the impact of AT-rich DNA on host fitness reduced transcription from
constitutive, but not activator-dependent, promoters
MRI identifies plantar plate pathology in the forefoot of patients with rheumatoid arthritis
Previous cadaveric studies have suggested that forefoot deformities at the metatarsophalangeal (MTP) joints in patients with rheumatoid arthritis (RA) might result from the failure of the ligamentous system and displacement of the plantar plates. This study aimed to examine the relationship between plantar plate pathology and the rheumatoid arthritis magnetic resonance imaging score (RAMRIS) of the lesser (second to fifth) MTP joints in patients with RA using high-resolution 3 T magnetic resonance imaging (MRI). In 24 patients with RA, the forefoot was imaged using 3 T MRI. Proton density fat-suppressed, T2-weighted fat-suppressed and T1-weighted post gadolinium sequences were acquired through 96 lesser MTP joints. Images were scored for synovitis, bone marrow oedema and bone erosion using the RAMRIS system and the plantar plates were assessed for pathology. Seventeen females and 7 males with a mean age of 55.5 years (range 37–71) and disease duration of 10.6 years (range 0.6–36) took part in the study. Plantar plate pathology was most frequently demonstrated on MRI at the fifth MTP joint. An association was demonstrated between plantar plate pathology and RAMRIS-reported synovitis, bone marrow oedema and bone erosion at the fourth and fifth MTP joints. In patients with RA, 3 T MRI demonstrates that plantar plate pathology at the lesser MTP joints is associated with features of disease severity. Plantar plate pathology is more common at the fourth and fifth MTP joints in subjects with RA in contrast to the predilection for the second MTP reported previously in subjects without RA
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Molecular basis of ALK1-mediated signalling by BMP9/BMP10 and their prodomain-bound forms
Abstract: Activin receptor-like kinase 1 (ALK1)-mediated endothelial cell signalling in response to bone morphogenetic protein 9 (BMP9) and BMP10 is of significant importance in cardiovascular disease and cancer. However, detailed molecular mechanisms of ALK1-mediated signalling remain unclear. Here, we report crystal structures of the BMP10:ALK1 complex at 2.3 Ã… and the prodomain-bound BMP9:ALK1 complex at 3.3 Ã…. Structural analyses reveal a tripartite recognition mechanism that defines BMP9 and BMP10 specificity for ALK1, and predict that crossveinless 2 is not an inhibitor of BMP9, which is confirmed by experimental evidence. Introduction of BMP10-specific residues into BMP9 yields BMP10-like ligands with diminished signalling activity in C2C12 cells, validating the tripartite mechanism. The loss of osteogenic signalling in C2C12 does not translate into non-osteogenic activity in vivo and BMP10 also induces bone-formation. Collectively, these data provide insight into ALK1-mediated BMP9 and BMP10 signalling, facilitating therapeutic targeting of this important pathway
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