N-glycosylation and homodimeric folding significantly enhance the immunoreactivity of Mycobacterium tuberculosis virulence factor CFP32 when produced in the yeast Pichia pastoris

We previously reported that immunoreactivity of recombinant CFP32 (Rv0577), a virulence factor of Mycobacterium tuberculosis, was higher when produced in transformed Pichia pastoris as compared to transformed E. coli. In this study, we show that this difference is partly due to the N-glycosylation of the recombinant CFP32 (rCFP32) by the yeast Pichia pastoris. In addition, SDS-PAGE and western blotting analysis of Mycobacterium bovis BCG and yeast-produced rCFP32 showed the presence of a band corresponding to a homodimeric state of the protein, unlike that of rCFP32 produced in E. coli. Computational modeling indicates that a single cysteine residue at position 193 of each monomer might bond to stabilize the homodimeric state of CFP32. Computational study showed that this residue is buried inside the protein core of E. coli-produced rCFP32 suggesting that rCFP32 may adopt a different folding in P. pastoris and BCG, in which C193 is solvent exposed. Surprisingly, an enzyme-linked immunosorbent assay using a generated monoclonal antibody (14D4) reveals the presence of a differential epitope that appears to be the consequence of the protein dimerization of the yeast- and BCG-, but not E.coli- produced, CFP32 recombinant form. We conclude that, in addition to N-glycosylation, homodimeric folding significantly enhances the immunoreactivity of rCFP32 and may these post-translational modifications may factor into the structure and function of native M. tuberculosis CFP32.

A microfluidic model for organ-specific extravasation of circulating tumor cells

Circulating tumor cells (CTCs) are the principal vehicle for the spread of non-hematologic cancer disease from a primary tumor, involving extravasation of CTCs across blood vessel walls, to form secondary tumors in remote organs. Herein, a polydimethylsiloxane-based microfluidic system is developed and characterized for in vitro systematic studies of organ-specific extravasation of CTCs. The system recapitulates the two major aspects of the in vivo extravasation microenvironment: local signaling chemokine gradients in a vessel with an endothelial monolayer. The parameters controlling the locally stable chemokine gradients, flow rate, and initial chemokine concentration are investigated experimentally and numerically. The microchannel surface treatment effect on the confluency and adhesion of the endothelial monolayer under applied shear flow has also been characterized experimentally. Further, the conditions for driving a suspension of CTCs through the microfluidic system are discussed while simultaneously maintaining both the local chemokine gradients and the confluent endothelial monolayer. Finally, the microfluidic system is utilized to demonstrate extravasation of MDA-MB-231 cancer cells in the presence of CXCL12 chemokine gradients. Consistent with the hypothesis of organ-specific extravasation, control experiments are presented to substantiate the observation that the MDA-MB-231 cell migration is attributed to chemotaxis rather than a random process.

[Terminal-lateral nerve anastomoses. Preliminary clinical report of two cases]

Nerve regeneration is based on three phenomenons of critical importance: neurotropism, nerve guidance and neurotrophis. These principles allow understanding the mechanisms of nerve suture and grafting, but also the newly described end-to-side nerve anastomoses. In this procedure, the distal stump of a severed nerve is anastomosed on the lateral side of an intact nerve, with or without removal of the perineurium. Authors report their beginning experience with this procedure (ten cases) and discuss the early results. End-to-side anastomosis seems to be a useful and reliable technique for clinical nerve repair. Even if nerve grafting remains the gold standard to bridge nerve defects, one has nothing to loose if a few minutes, anastomosing the severed nerve on the lateral side of an intact nerve, rather than doing nothing.

[The reverse auricular flap. A new flap]

The authors describe a new chondrocutaneous reverse island flap from the ear helix for nose and eyelid reconstruction. Anatomic studies showed that the blood supply of the helix is derived from the superficial temporal system. The presence of vascular communications between the anterior frontal branch of the superficial temporal artery and the supra-orbital and supra-trochlear arterial systems allows this flap to be used in a reverse vascular flow fashion. Three flaps have been successfully used for reconstruction of alar and nose tip defects and in one case for total lower eyelid reconstruction. The donor site is repaired with an advancement and rotation flap from the helical rim giving an acceptable result. In this paper, the authors propose a new pedicle flap for reconstruction of complex nose and eyelid defects.

[Abdominoplasty with dissociated intraparietal liposuction. Technical note]

Liposuction has greatly contributed to the improvement of the aesthetic result of abdominoplasties. However, one should consider the high rate of seroma when liposuction is performed via an inferior approach during abdominoplasty. The authors present a new approach to achieve complete liposuction of the abdominal wall during conventional abdominoplasty. This approach is carried out via submammary incision after previous undermining of the abdominal wall. A permanent assessment of the thickness of the wall allows the liposuction to stay strictly in fat tissue. Finally, there is a total independence between liposuction and the undermining procedure which allows minimization of the postoperative seroma. This technic seems particularly useful in a context of extensive abdominal adipose with flaccidity of the abdominal wall, requiring extensive undermining. Thanks to this procedure, the authors have performed a one-stage operation in many cases in which two operations would necessary previously have been.