Unifying classification for transdiaphragmatic intercostal hernia and other costal margin injuries.

OBJECTIVES: Taxonomy of injuries involving the costal margin is poorly described and surgical management varies. These injuries, though commonly caused by trauma, may also occur spontaneously, in association with coughing or sneezing, and can be severe. Our goal was to describe our experience using sequential segmental analysis of computed tomographic (CT) scans to perform accurate assessment of injuries around the costal margin. We propose a unifying classification for transdiaphragmatic intercostal hernia and other injuries involving the costal margin. We identify the essential components and favoured techniques of surgical repair. METHODS: Patients presenting with injuries to the diaphragm or to the costal margin or with chest wall herniation were included in the study. We performed sequential segmental analysis of CT scans, assessing individual injury patterns to the costal margin, diaphragm and intercostal muscles, to create 7 distinct logical categories of injuries. Management was tailored to each category, adapted to the individual case when required. Patients with simple traumatic diaphragmatic rupture were considered separately, to allow an estimation of the relative incidence of injuries to the costal margin compared to those of the diaphragm alone. RESULTS: We identified 38 patients. Of these, 19 had injuries involving the costal margin and/or intercostal muscles (group 1). Sixteen patients in group 1 underwent surgery, 2 of whom had undergone prior surgery, with 4 requiring a novel double-layer mesh technique. Nineteen patients (group 2) with diaphragmatic rupture alone had a standard repair. CONCLUSIONS: Sequential analysis of CT scans of the costal margin, diaphragm and intercostal muscles defines accurately the categories of injury. We propose a 'Sheffield classification' in order to guide the clinical team to the most appropriate surgical repair. A variety of surgical techniques may be required, including a single- or double-layer mesh reinforcement and plate and screw fixation.

Constructs for the expression of repeating triple-helical protein domains.

The development of novel scaffolds will be an important aspect in future success of tissue engineering. Scaffolds will preferably contain information that directs the cellular content of constructs so that the new tissue that is formed is closely aligned in structure, composition and function to the target natural tissue. One way of approaching this will be the development of novel protein-based constructs that contain one or more repeats of functional elements derived from various proteins. In the present case, we describe a strategy to make synthetic, recombinant triple-helical constructs that contain repeat segments of biologically relevant domains. Copies of a DNA fragment prepared by PCR from human type III collagen have been inserted in a co-linear contiguous fashion into the yeast expression vector YEpFlag-1, using sequential addition between selected restriction sites. Constructs containing 1, 2 and 3 repeats were designed to maintain the (Gly-X-Y) repeat, which is essential for the formation of an extended triple helix. All constructs gave expressed protein, with the best being the 3-repeat construct which was readily secreted. This material had the expected composition and N-terminal sequence. Incubation of the product at low temperature led to triple-helix formation, shown by reaction with a conformation dependent monoclonal antibody.

Characterization of a protein-based adhesive elastomer secreted by the Australian frog Notaden bennetti.

When provoked, Notaden bennetti frogs secrete an exudate which rapidly forms a tacky elastic solid ("frog glue"). This protein-based material acts as a promiscuous pressure-sensitive adhesive that functions even in wet conditions. We conducted macroscopic tests in air to assess the tensile strength of moist glue (up to 78 +/- 8 kPa) and the shear strength of dry glue (1.7 +/- 0.3 MPa). We also performed nanomechanical measurements in water to determine the adhesion (1.9-7.2 nN or greater), resilience (43-56%), and elastic modulus (170-1035 kPa) of solid glue collected in different ways. Dry glue contains little carbohydrate and consists mainly of protein. The protein complement is rich in Gly (15.8 mol %), Pro (8.8 mol %), and Glu/Gln (14.1 mol %); it also contains some 4-hydroxyproline (4.6 mol %) but no 5-hydroxylysine or 3,4-dihydroxyphenylalanine (L-Dopa). Denaturing gel electrophoresis of the glue reveals a characteristic pattern of proteins spanning 13-400 kDa. The largest protein (Nb-1R, apparent molecular mass 350-500 kDa) is also the most abundant, and this protein appears to be the key structural component. The solid glue can be dissolved in dilute acids; raising the ionic strength causes the glue components to self-assemble spontaneously into a solid which resembles the starting material. We describe scattering studies on dissolved and solid glue and provide microscopy images of glue surfaces and sections, revealing a porous interior that is consistent with the high water content (85-90 wt %) of moist glue. In addition to compositional similarities with other biological adhesives and well-known elastomeric proteins, the circular dichroism spectrum of dissolved glue is almost identical to that for soluble elastin and electron and scanning probe microscopy images invite comparison with silk fibroins. Covalent cross-linking does not seem to be necessary for the glue to set.