〈Case Reports〉 A case of abdominal wall abscess caused by fish bone strayed into umbilical hernia

[Abstract] A woman who was 70’s in age was hospitalized with a slow-growing abdominal mass for about one month. An abdominal CT scan showed 35 mm diameter abscess formation under the rectus abdominis muscle, and about 20 mm length high density linear shadow was identified within the abscess. Because she had mild abdominal tenderness, she was followed for a week. A week later, the abscess enlarged to 52 mm in size and an emergency laparotomy was performed. Intestinal perforation was not detected after removal of the fish bone, and abscess drainage was performed. She was discharged from the hospital on the 30th postoperative day without any postoperative complications. In cases of fish bone penetration with abdominal pain, it is important to determine treatment strategy according to abdominal symptoms and CT findings

Structural basis of α-catenin recognition by EspB from enterohaemorrhagic E. coli based on hybrid strategy using low-resolution structural and protein dissection.

Enterohaemorrhagic E. coli (EHEC) induces actin reorganization of host cells by injecting various effectors into host cytosol through type III secretion systems. EspB is the natively partially folded EHEC effector which binds to host α-catenin to promote the actin bundling. However, its structural basis is poorly understood. Here, we characterize the overall structural properties of EspB based on low-resolution structural data in conjunction with protein dissection strategy. EspB showed a unique thermal response involving cold denaturation in the presence of denaturant according to far-UV circular dichroism (CD). Small angle X-ray scattering revealed the formation of a highly extended structure of EspB comparable to the ideal random coil. Various disorder predictions as well as CD spectra of EspB fragments identified the presence of α-helical structures around G41 to Q70. The fragment corresponding to this region indicated the thermal response similar to EspB. Moreover, this fragment showed a high affinity to C-terminal vinculin homology domain of α-catenin. The results clarified the importance of preformed α-helix of EspB for recognition of α-catenin

Sequence of EspB from EHEC and the result of secondary structure prediction by Jpred3 (http://www.compbio.dundee.ac.uk/www-jpred/) [49].

<p>The sequence region of α-catenin binding site previously determined <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071618#pone.0071618-Kodama1" target="_blank">[2]</a> is boxed in red and myosin binding sites assigned from the sequence similarity with EPEC EspB <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071618#pone.0071618-Iizumi1" target="_blank">[5]</a> is boxed in blue. Regions predicted as helix or strand are indicated as “H” or “E”, respectively.</p

Structural properties of short fragments of EspB.

<p>(A) Far-UV CD spectra for the peptides assuming α-helical structures. EspB41–60 (l>), EspB51–70 (◊), EspB61–80 (•), EspB71–90 (▪), EspB41–70 (◂). (B) Spectra for the peptides assuming unfolded structures. EspB1–20 (□), EspB11–30 (Δ), EspB21–40 (∇), EspB31–50 (</p

Affinity of the EspB fragments to α-catenin635–906 analyzed by fluorescence anisotropy.

<p>Each EspB peptide was modified with a fluorescein moiety at the N-terminus. (A), Titration curves for the peptides bound to α-catenin. EspB (○), EspB41–60 (l>), EspB51–70 (◊), EspB61–80 (•), EspB41–70 (◂). (B) Titration results obtained for the peptides unable to bind to α-catenin635–906. EspB1–20(□), EspB11–30 (Δ), EspB21–40 (∇), EspB31–50 (</p

Far-UV CD spectra of EspB fragments.

<p>(A) Schematic representation of the fragments prepared in this study. (B) Raw ellipticity data (<i>θ</i>_obs) obtained by full length EspB (circles), EspB1–176 (squares) and EspB177–312 (triangles). The protein concentration for each protein was 15 µM. Broken line indicates the sum of the spectra of EspB1–176 and EspB177–312. (C) Another representation of spectra shown in panel B expressed as mean residue ellipticity, [<i>θ</i>].</p

Thermodynamic parameters of unfolding of EspB and EspB41–70 in the presence of GdnHCl at pH 7.0.

a<p>Estimated from linear extrapolation of Δ<i>G</i>_20°C obtained by the analysis of the data in the presence of GdnHCl as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071618#pone-0071618-g001" target="_blank">Fig. 1</a>.</p>b<p>Not available.</p>c<p>Same as above.</p

Thermal transition of EspB monitored by CD spectra at pH 7.0 in the presence or absence of GdnHCl.

<p>(A) The Far-UV CD spectra of EspB obtained at various temperatures in the absence of GdnHCl. Numbers refer to the temperature in °C. (B) Temperature dependences of the ellipticity at 222 nm ([<i>θ</i>]₂₂₂) of EspB in the absence (O) or presence of 2.0 (□), 3.0 (Δ), 4.0 (◊), 5.0 (∇), 6.0 (+) and 7.0 M (X) GdnHCl. Lines are the results of curve-fitting. (C) Linear dependence of Δ<i>G</i>_20°C against GdnHCl concentrations to estimate the Δ<i>G</i>_20°C in the absence of GdnHCl (Δ<i>G</i>_water) and <i>m</i> value from the slope of the plots. The Δ<i>G</i>_20°C obtained by the thermal transition curves of EspB and EspB41–70 are shown as circles and squares, respectively. (D) Temperature dependences of the ellipticity at 222 nm ([<i>θ</i>]₂₂₂) of EspB41–70 in the absence (O) or presence of 4.0 (◊), 5.0 (∇), 6.0 (+) and 7.0 M (X) GdnHCl. Lines are the results of curve-fitting.</p

Structural properties of EspB revealed by SAXS.

<p>(A) <i>P</i>_r function of EspB (circles) calculated from SAXS profile and that of phosphotriesterase (squares) calculated from its atomic coordinates (1EYW) downloaded from Protein Data Bank. The structure of phosphotriesterase is represented as a space-filling model (inset) to illustrate the globular nature of the molecule. This model was produced by PyMol (<a href="http://www.pymol.org" target="_blank">http://www.pymol.org</a>). (B) Guinier plots. Raw data are represented by circles. Lines indicate the results of fitting against linear regions of the raw data. Protein concentrations were 2.0, 5.8, 8.6 and 11.5 mg mL⁻¹ from the bottom to the top in panel B, respectively. (C) Protein concentration dependence of square of <i>R</i>_g² calculated from the slope of Guinier plot in panel B.</p