Fabrication and mechanical characterization of hydrogel-based 3D cell-like structures.

In this article, we demonstrate the fabrication of 3D cell-like structures using a femtosecond laser-based two-photon polymerization technique. By employing poly(ethylene glycol) diacrylate monomers as a precursor solution, we fabricate 3D hemispheres that resemble morphological and biomechanical characteristics of natural cells. We employ an optical tweezers-based microrheology technique to measure the viscoelastic properties of the precursor solutions inside and outside the structures. In addition, we demonstrate the interchangeability of the precursor solution within fabricated structures without impairing the microstructures. The combination of two-photon polymerization and microrheological measurements by optical tweezers demonstrated here represents a powerful toolbox for future investigations into cell mimic and artificial cell studies.

Retrospectively assessing evaluation and management of artificial-intelligence detected nodules on uninterpreted chest radiographs in the era of radiologists shortage.

PURPOSE: High volumes of chest radiographs (CXR) remain uninterpreted due to severe shortage of radiologists. These CXRs may be informally reported by non-radiologist physicians, or not reviewed at all. Artificial intelligence (AI) software can aid lung nodule detection. Our aim was to assess evaluation and management by non-radiologists of uninterpreted CXRs with AI detected nodules, compared to retrospective radiology reports. MATERIALS AND METHODS: AI detected nodules on uninterpreted CXRs of adults, performed 30/6/2022-31/1/2023, were evaluated. Excluded were patients with known active malignancy and duplicate CXRs of the same patient. The electronic medical records (EMR) were reviewed, and the clinicians' notes on the CXR and AI detected nodule were documented. Dedicated thoracic radiologists retrospectively interpreted all CXRs, and similarly to the clinicians, they had access to the AI findings, prior imaging and EMR. The radiologists' interpretation served as the ground truth, and determined if the AI-detected nodule was a true lung nodule and if further workup was required. RESULTS: A total of 683 patients met the inclusion criteria. The clinicians commented on 386 (56.5%) CXRs, identified true nodules on 113 CXRs (16.5%), incorrectly mentioned 31 (4.5%) false nodules as real nodules, and did not mention the AI detected nodule on 242 (35%) CXRs, of which 68 (10%) patients were retrospectively referred for further workup by the radiologist. For 297 patients (43.5%) there were no comments regarding the CXR in the EMR. Of these, 77 nodules (11.3%) were retrospectively referred for further workup by the radiologist. CONCLUSION: AI software for lung nodule detection may be insufficient without a formal radiology report, and may lead to over diagnosis or misdiagnosis of nodules.

Potential Pitfalls in Imaging of the Mediastinum.

Chest computed tomography (CT) is the modality of choice for mediastinal imaging. The high-resolution images provided by multi-detector CT result in routine visualization of normal anatomic structures, which can be confused with pathology. In addition, many mediastinal abnormalities are discovered incidentally, with a routine chest CT protocol which may be insufficient for definite diagnosis. Awareness of the spectrum of potential pitfalls of mediastinal imaging, artifacts related to flow, motion, and solutions to mitigate these problematic issues is important in accurate interpretation. The purpose of this review is to highlight and discuss potential pitfalls in the imaging of the mediastinum.

Pulmonary Computed Tomography Parenchymal and Vascular Features Diagnostic of Postablation Pulmonary Vein Stenosis.

PURPOSE: The purpose of this study was to define the full spectrum of pulmonary computed tomography (CT) changes characteristic of postablation pulmonary vein stenosis (PVS). MATERIALS AND METHODS: We retrospectively reviewed our pulmonary vein isolation database. PVS was graded as follows: grade 1:<50%, grade 2: 50% to 75%, grade 3: 76% to 99%, and grade 4: total occlusion. CT parenchymal and vascular changes were detected and correlated with clinical course and nuclear scans. RESULTS: Of 486 patients who underwent pulmonary vein isolation, 56 patients (11%) were symptomatic, prompting referral to CT evaluation. Grades 1, 2, 3, and 4 PVS were documented in 42, 1, 2, and 11 patients, respectively. Apart from PVS, abnormal CT findings were present only in patients with PVS grades 2 to 4. Pulmonary parenchymal changes (consolidation, "ground glass" opacities, interlobular septal thickening, and volume loss) were found in PVS grades 2 to 4. Pulmonary vascular changes (oligemia, "sluggish flow," and collateral mediastinal vessels) were shown in patients with grades 3 to 4 PVS. Concomitant nuclear scans documented reduced lung perfusion. All findings were located to the lobe drained by the affected vein. Complete resolution of pulmonary findings on follow-up CT scans was demonstrated in 20% of patients. Eleven stents were inserted in 7 patients with PVS grades 2 to 4, none of which demonstrated radiologic or clinical resolution. CONCLUSIONS: A typical CT complex of both parenchymal and vascular findings in the affected lobe is diagnostic of postablation PVS. Lack of clinical and radiologic resolution in most patients, even after stent insertion, further highlights the importance of early recognition of this underdiagnosed condition.

Anion-independent iron coordination by the Campylobacter jejuni ferric binding protein.

Campylobacter jejuni, the leading cause of human gastroenteritis, expresses a ferric binding protein (cFbpA) that in many pathogenic bacteria functions to acquire iron as part of their virulence repertoire. Recombinant cFbpA is isolated with ferric iron bound from Escherichia coli. The crystal structure of cFbpA reveals unprecedented iron coordination by only five protein ligands. The histidine and one tyrosine are derived from the N-terminal domain, whereas the three remaining tyrosine ligands are from the C-terminal domain. Surprisingly, a synergistic anion present in all other characterized ferric transport proteins is not observed in the cFbpA iron-binding site, suggesting a novel role for this protein in iron uptake. Furthermore, cFbpA is shown to bind iron with high affinity similar to Neisserial FbpA and exhibits an unusual preference for ferrous iron (oxidized subsequently to the ferric form) or ferric iron chelated by oxalate. Sequence and structure analyses reveal that cFbpA is a member of a new class of ferric binding proteins that includes homologs from invasive and intracellular bacteria as well as cyanobacteria. Overall, six classes are defined based on clustering within the tree and by their putative iron coordination. The absence of a synergistic anion in the iron coordination sphere of cFbpA also suggests an alternative model of evolution for FbpA homologs involving an early iron-binding ancestor instead of a requirement for a preexisting anion-binding ancestor.

Specificity of the synergistic anion for iron binding by ferric binding protein from Neisseria gonorrhoeae.

Ferric binding protein in Neisseria gonorrhoeae (nFbpA) transports iron from outer membrane receptors for host proteins across the periplasm to a permease in an alternative pathway to the use of siderophores in some pathogenic bacteria. Phosphate and nitrilotriacetate, both at pH 8, and vanadate at pH 9 are shown to be synergistic in promoting ferric binding to nFbpA, in contrast to carbonate and sulfate. Interestingly, only phosphate produces the fully closed conformation of nFbpA as defined by native electrophoresis. The role of phosphate was probed by constructing three mutants: Q58E, Q58R, and G140H. The anion and iron binding properties of the Q58E mutant are similar to the wild-type protein, implying that one phosphate oxygen is a hydrogen bond donor and may in part define the specificity of nFbpA for phosphate over sulfate. Phosphate is a weakly synergistic anion in the Q58R and G140H mutants, and these mutants do not form completely closed structures. Ferric binding was investigated by both isothermal titration and differential scanning calorimetry. The apparent affinity of nFbpA for iron in a solution of 30 mM citrate is 1 order of magnitude larger in the presence (K(app)= 1.7 x 10(5) M(-1)) of phosphate than in its absence (K(app) = 1.6 x 10(4) M(-1)) at pH 7. Similar results were obtained at pH 8. This increase in affinity with phosphate as well as the formation of closed structure allows nFbpA to compete for free ferric ions in solution and suggests that ferric binding to nFbpA is regulated by the synergistic phosphate anion at sites of iron uptake.