Individuals who receive a third mRNA vaccine dose show enhanced protection against severe COVID-19, but little is known about the impact of breakthrough infections on memory responses. Here, we ...examine the memory antibodies that develop after a third or fourth antigenic exposure by Delta or Omicron BA.1 infection, respectively. A third exposure to antigen by Delta breakthrough increases the number of memory B cells that produce antibodies with comparable potency and breadth to a third mRNA vaccine dose. A fourth antigenic exposure with Omicron BA.1 infection increased variant-specific plasma antibody and memory B cell responses. However, the fourth exposure did not increase the overall frequency of memory B cells or their general potency or breadth compared to a third mRNA vaccine dose. In conclusion, a third antigenic exposure by Delta infection elicits strain-specific memory responses and increases in the overall potency and breadth of the memory B cells. In contrast, the effects of a fourth antigenic exposure with Omicron BA.1 are limited to increased strain-specific memory with little effect on the potency or breadth of memory B cell antibodies. The results suggest that the effect of strain-specific boosting on memory B cell compartment may be limited.
Type II cadherins are cell-cell adhesion proteins critical for tissue patterning and neuronal targeting but whose molecular binding code remains poorly understood. Here, we delineate binding ...preferences for type II cadherin cell-adhesive regions, revealing extensive heterophilic interactions between specific pairs, in addition to homophilic interactions. Three distinct specificity groups emerge from our analysis with members that share highly similar heterophilic binding patterns and favor binding to one another. Structures of adhesive fragments from each specificity group confirm near-identical dimer topology conserved throughout the family, allowing interface residues whose conservation corresponds to specificity preferences to be identified. We show that targeted mutation of these residues converts binding preferences between specificity groups in biophysical and co-culture assays. Our results provide a detailed understanding of the type II cadherin interaction map and a basis for defining their role in tissue patterning and for the emerging importance of their heterophilic interactions in neural connectivity.
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•Mouse type II cadherins form homophilic and selective heterophilic interactions•Binding profiles are shared within groups of phylogenetically related cadherins•Interface differences in a canonical adhesive dimer govern group-wise specificity•These molecular specificities drive localization of cadherins to adhesive contacts
Type II cadherins are a family of vertebrate cell adhesion proteins expressed primarily in the CNS. Brasch et al. measure binding between adhesive fragments, revealing homophilic and extensive selective heterophilic binding with specificities that define groups of similar cadherins. Structures reveal common adhesive dimers, with residues governing cell-adhesive specificity.
Type I cadherin cell-adhesion proteins are similar in sequence and structure and yet are different enough to mediate highly specific cell-cell recognition phenomena. It has previously been shown that ...small differences in the homophilic and heterophilic binding affinities of different type I family members can account for the differential cell-sorting behavior. Here we use a combination of X-ray crystallography, analytical ultracentrifugation, surface plasmon resonance and double electron-electron resonance (DEER) electron paramagnetic resonance spectroscopy to identify the molecular determinants of type I cadherin dimerization affinities. Small changes in sequence are found to produce subtle structural and dynamical changes that impact relative affinities, in part via electrostatic and hydrophobic interactions, and in part through entropic effects because of increased conformational heterogeneity in the bound states as revealed by DEER distance mapping in the dimers. These findings highlight the remarkable ability of evolution to exploit a wide range of molecular properties to produce closely related members of the same protein family that have affinity differences finely tuned to mediate their biological roles.
The interest in electroconductive textiles has tremendously increased over the last few years. By functionalizing textile surfaces with thin layers of metal, electrical conductivity can be combined ...with flexibility and pliability. We adopted this approach and deposited a thin layer of soft gold onto polypyrrole- and copper-coated para-aramid yarns in an electroless way. This paper presents the coating method for the gold deposition and presents some initial results on the characterization of the gold layer and the performance of the resulting yarns. A deposition solution was used which contained a gold salt, sulfite and thiosulfate. The pH value and temperature of the solution was optimized to result in a smooth and homogenous gold layer. Performance tests showed that the coated yarns offered an excellent electrical conductivity combined with good mechanical properties and satisfying resistance to washing. In addition, electrochemical impedance measurements revealed that the gold coated yarns are promising electrode materials to measure biomedical signals.
Irreversible right ventricular (RV) failure with myocardial damage may precipitate fatal outcome in acute pulmonary embolism (APE). Cytoplasmic heart-type fatty acid binding protein (H-FABP) is a ...sensitive and specific biomarker of myocardial damage. We assessed which biomarker of myocardial damage or RV stretching is the most useful for short-term risk stratification in APE.
We analyzed 77 patients (51 F, 26 M) aged 65.3
±
16.0 years with confirmed APE. On admission, systemic blood pressure and transthoracic echocardiography (for RV overload) were recorded and plasma concentrations of myoglobin (Mb), cardiac troponin T (cTnT), N-terminal fragment of proBNP (NT-proBNP) and H-FABP were evaluated.
Fifteen (19.5%) patients died and 24 (31.2%) experienced complicated clinical course (CCC)-death/thrombolysis/cardiopulmonary resuscitation/intravenous vasopressors. Hazard ratio analysis demonstrated that plasma H-FABP, Mb, cTnT and NT-proBNP concentrations predicted fatal outcome. When only APE-related deaths were considered, plasma H-FABP concentrations indicated fatal outcome. Multivariate hazard ratio analysis revealed H-FABP as the only 30-day mortality predictor (HR 1.02 CI 95% 1.01–1.05).
H-FABP measured on admission is useful for short-term risk stratification in APE. It appears to be superior to cTnT, NT-proBNP and Mb in the prediction of 30-day APE-related mortality.
Several studies demonstrated feasibility of visual assessment of the common femoral artery Doppler waveform, in an indirect evaluation of aorto-iliac segment stenosis. Patients with cardiac diseases ...referred for echocardiography often have coexistent arterial pathology. Since many of them are potential candidates for endovascular procedures, we decided to study, whether echocardiography can be useful for detection of aorto-iliac occlusive disease. We evaluated 92 patients with abdominal aortic aneurysm or peripheral artery occlusive disease, referred from the vascular surgery department for cardiac evaluation before surgery. At the end of an echocardiographic examination, evaluation of flow in the distal external iliac arteries with an echocardiographic probe was performed. The Doppler waveform was classified into normal—with early diastolic flow reversal or abnormal—without early diastolic flow reversal. Echocardiographic results were compared in a blinded fashion with reports from computed tomography angiography. Overall there were 58 iliac segments with significant (≥70%) area stenosis or occlusion and 126 iliac segments without significant disease on computed tomography angiography. Abnormal Doppler waveform was found in 56 out of 58 abnormal iliac segments—sensitivity 97%, and normal waveform was found in 106 out of 126 normal iliac segments—specificity 84%. Positive predictive value of abnormal Doppler waveform for significant iliac disease was 74%, and negative predicting value was 98%. Detection of significant stenoses in aorto-iliac segments is feasible with echocardiography. Further studies are necessary to evaluate its potential utility in a population of patients with cardiac disease referred for echocardiographic study.
SARS-CoV-2 infection or vaccination produces neutralizing antibody responses that contribute to better clinical outcomes. The receptor-binding domain (RBD) and the N-terminal domain (NTD) of the ...spike trimer (S) constitute the two major neutralizing targets for antibodies. Here, we use NTD-specific probes to capture anti-NTD memory B cells in a longitudinal cohort of infected individuals, some of whom were vaccinated. We found 6 complementation groups of neutralizing antibodies. 58% targeted epitopes outside the NTD supersite, 58% neutralized either Gamma or Omicron, and 14% were broad neutralizers that also neutralized Omicron. Structural characterization revealed that broadly active antibodies targeted three epitopes outside the NTD supersite including a class that recognized both the NTD and SD2 domain. Rapid recruitment of memory B cells producing these antibodies into the plasma cell compartment upon re-infection likely contributes to the relatively benign course of subsequent infections with SARS-CoV-2 variants, including Omicron.
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•Vaccination boosts anti-NTD responses against Omicron in convalescent individuals•Natural SARS-CoV-2 infection induces variant-reactive memory B cell responses to NTD•Anti-NTD neutralizing antibodies form 6 complementation groups•Structures of anti-NTD broad neutralizing antibodies reveal epitopes outside supersite
Most neutralizing antibodies to SARS-CoV-2 NTD characterized to date bind a single supersite, but these antibodies were obtained by methods that were not NTD-specific. Wang et al. analyzed SARS-CoV-2 NTD-specific memory B cell responses in a longitudinal cohort of infected individuals, some of whom were vaccinated. Structural analysis revealed neutralizing epitopes conserved among variants of concern outside the NTD supersite.
The SARS-CoV-2 pandemic prompted a global vaccination effort and the development of numerous COVID-19 vaccines at an unprecedented scale and pace. As a result, current COVID-19 vaccination regimens ...comprise diverse vaccine modalities, immunogen combinations, and dosing intervals. Here, we compare vaccine-specific antibody and memory B cell responses following two-dose mRNA, single-dose Ad26.COV.2S, and two-dose ChAdOx1, or combination ChAdOx1/mRNA vaccination. Plasma-neutralizing activity, as well as the magnitude, clonal composition, and antibody maturation of the RBD-specific memory B cell compartments, showed substantial differences between the vaccination regimens. While individual monoclonal antibodies derived from memory B cells exhibited similar binding affinities and neutralizing potency against Wuhan-Hu-1 SARS-CoV-2, there were significant differences in epitope specificity and neutralizing breadth against viral variants of concern. Although the ChAdOx1 vaccine was inferior to mRNA and Ad26.COV.2S in several respects, biochemical and structural analyses revealed enrichment in a subgroup of memory B cell neutralizing antibodies with distinct RBD-binding properties resulting in remarkable potency and breadth.
Transcription factors bind to their binding sites over a wide range of affinities, yet how differences in affinity are encoded in DNA sequences is not well understood. Here, we report X-ray crystal ...structures of four heterodimers of the Hox protein AbdominalB bound with its cofactor Extradenticle to four target DNA molecules that differ in affinity by up to ∼20-fold. Remarkably, despite large differences in affinity, the overall structures are very similar in all four complexes. In contrast, the predicted shapes of the DNA binding sites (i.e., the intrinsic DNA shape) in the absence of bound protein are strikingly different from each other and correlate with affinity: binding sites that must change conformations upon protein binding have lower affinities than binding sites that have more optimal conformations prior to binding. Together, these observations suggest that intrinsic differences in DNA shape provide a robust mechanism for modulating affinity without affecting other protein-DNA interactions.
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•The X-ray crystal structures of four Hox-cofactor-DNA complexes were solved•Although affinity to DNA differs up to 20-fold, the ternary structures are very similar•The predicted intrinsic DNA shapes of the binding sites correlate with affinity•Hox N-terminal arm paths in the minor groove correlate with DNA shape readout
By solving the structures of four ternary Hox-Exd-DNA complexes, Zeiske et al. show that lower-affinity binding sites have intrinsic DNA shapes that must change conformation upon protein binding, and that the paths of Hox N-terminal arms determine the extent to which DNA shape can be read out.
Aims Despite growing interest in biomarkers application for risk evaluation in acute pulmonary embolism (APE), no decision-making levels have been defined. Methods and results We developed a ...biomarker-based risk stratification in 100 consecutive, normotensive on admission, APE patients (35 males, 65 females, 62±18 years). On admission serum NT-proBNP and cardiac troponin T (cTnT) levels were assessed and echocardiography was performed. All-cause 40-day mortality was 15% and APE mortality was 8%. In univariable analysis, cTnT>0.07 µg/L predicted all-cause mortality, hazard ratio (HR) 9.2 (95% CI: 3.3–26.1, P<0.0001), and APE mortality, HR 18.1 (95% CI: 3.6–90.2, P=0.0004); similarly, NT-proBNP>7600 ng/L predicted all-cause and APE mortalities HR 6.7 (95% CI: 2.4–19.0, P=0.0003) and 7.3 (95% CI: 1.7–30.6, P=0.007). NT-proBNP<600 ng/L indicated uncomplicated outcome. Multivariable analysis revealed that cTnT>0.07 µg/L was the most significant independent predictor, whereas NT-proBNP and systemic systolic blood pressure measured on admission and echocardiographic parameters were non-significant. APE mortality in patients with NT-proBNP≥600 ng/L and cTnT≥0.07 µg/L reached 33%. NT-proBNP<600 ng/L indicated group without deaths. APE mortality for patients with NT-proBNP≥600 ng/L and cTnT<0.07 µg/L was 3.7%. Incorporation of echocardiographic data did not improve group selection. Conclusion Simultaneous measurement of serum cTnT and NT-proBNP allows for precise APE prognosis. Normotensive patients on admission with cTnT≥0.07 µg/L and NT-proBNP≥600 ng/L are at high risk of APE mortality, whereas NTproBNP<600 ng/L indicates excellent prognosis.
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