Delayed Tension Hemothorax With Nondisplaced Rib Fractures After Blunt Thoracic Trauma.

Blunt thoracic trauma often causes rib fractures, hemothorax, and pneumothorax. Although there is no established definition regarding the duration and management of delayed hemothorax, it commonly occurs in a few days and exhibits at least one displaced rib fracture. Moreover, delayed hemothorax rarely develops tension hemothorax. A 58-year-old male who had a motorcycle accident received conservative treatment from his orthopedic doctor. He felt a sudden severe chest pain 19 days after the accident. Contrast-enhanced computed tomography (CT) of the chest revealed multiple left-sided rib fractures without displacement, left pleural effusion, and extravasation near the intercostal space of the seventh rib fracture. After transfer to our hospital and a plain CT scan, which showed a more mediastinal shift toward the right, his condition deteriorated with cardiorespiratory embarrassment, such as restlessness, hypotension, and neck vein distention. We diagnosed him with obstructive shock due to tension hemothorax. Immediate chest drainage ameliorated restlessness and elevated blood pressure. Here, we report an extremely rare and atypical case of delayed tension hemothorax after blunt thoracic trauma without displaced rib fractures.

Basic Fibroblast Growth Factor Fused with Tandem Collagen-Binding Domains from Clostridium histolyticum Collagenase ColG Increases Bone Formation.

Basic fibroblast growth factor 2 (bFGF) accelerates bone formation during fracture healing. Because the efficacy of bFGF decreases rapidly following its diffusion from fracture sites, however, repeated dosing is required to ensure a sustained therapeutic effect. We previously developed a fusion protein comprising bFGF, a polycystic kidney disease domain (PKD; s2b), and collagen-binding domain (CBD; s3) sourced from the Clostridium histolyticum class II collagenase, ColH, and reported that the combination of this fusion protein with a collagen-like peptide, poly(Pro-Hyp-Gly)10, induced mesenchymal cell proliferation and callus formation at fracture sites. In addition, C. histolyticum produces class I collagenase (ColG) with tandem CBDs (s3a and s3b) at the C-terminus. We therefore hypothesized that a bFGF fusion protein containing ColG-derived tandem CBDs (s3a and s3b) would show enhanced collagen-binding activity, leading to improved bone formation. Here, we examined the binding affinity of four collagen anchors derived from the two clostridial collagenases to H-Gly-Pro-Arg-Gly-(Pro-Hyp-Gly)12-NH2, a collagenous peptide, by surface plasmon resonance and found that tandem CBDs (s3a-s3b) have the highest affinity for the collagenous peptide. We also constructed four fusion proteins consisting of bFGF and s3 (bFGF-s3), s2b-s3b (bFGF-s2b-s3), s3b (bFGF-s3b), and s3a-s3b (bFGF-s3a-s3b) and compared their biological activities to those of a previous fusion construct (bFGF-s2b-s3) using a cell proliferation assay in vitro and a mouse femoral fracture model in vivo. Among these CB-bFGFs, bFGF-s3a-s3b showed the highest capacity to induce mesenchymal cell proliferation and callus formation in the mice fracture model. The poly(Pro-Hyp-Gly)10/bFGF-s3a-s3b construct may therefore have the potential to promote bone formation in clinical settings.