Transluminal closure for NOTES: an ex vivo study comparing leak pressures of various gastrotomy and colotomy closure modalities.

BACKGROUND AND STUDY AIMS: Transluminal closure is fundamental to the safe introduction of natural orifice transluminal endoscopic surgery (NOTES) into humans. Suture, staples, and clips have been used. We aimed to evaluate the acute strength of various gastrotomy and colotomy closure techniques in an ex vivo porcine model by assessing air leak pressures. PATIENTS AND METHODS: The following closure modalities were assessed with at least five samples per arm: conventional open/laparoscopic suturing techniques including full-thickness interrupted sutures, double-layer sutures, and purse-string sutures, as well as endoscopic clips and endoscopic staples. Historical values for transgastric closures with hand-sewn interrupted sutures, endoscopic clips, and a prototype endoscopic suture device were used from our laboratory's prior study. RESULTS: Using Kruskal-Wallis analysis, the overall comparisons were significant ( P = 0.0038 for gastrotomy closure; P = 0.0018 for colotomy closure). Post hoc paired comparisons revealed that the difference between all closure arms versus negative control were significant. Significance could not be established among the various closure arms. However, trends suggested hand-sewn double-layer sutures, endoscopic staples, and both hand-sewn and endoscopically-placed purse-string sutures produced the strongest closures. Furthermore, endoscopic clips appeared sufficient for colotomy closure when ideally placed. CONCLUSIONS: Suture (both hand-sewn and endoscopically deployed) appears to produce the strongest closures in both stomach and colon, with the important caveats that (1) a continuous through-thickness suture track be avoided, such as in the full-thickness closure, or (2) suture holes be buried, such as in the purse-string configuration. When suture tracks are full-thickness, they can serve as leak sites. Staples and clips can produce comparable closures, but only under ideal conditions.

Transcolonic ventral wall hernia mesh fixation in a porcine model.

BACKGROUND AND STUDY AIMS: A natural orifice transluminal endoscopic surgery (NOTES) approach to ventral wall hernia repair may represent a potentially less invasive alternative to current transabdominal surgical techniques. We aimed to investigate the feasibility of using transcolonic NOTES to deliver hernia repair mesh into the peritoneal cavity, as well as the ability to manipulate composite mesh and secure it to the abdominal wall. METHODS: Five pigs weighing 20 to 25 kg were used in this feasibility study involving two acute and three survival experiments. A prototype mesh delivery system was used to transfer 1.5 - 2-cm x 2.5 - 3-cm pieces of composite hernia mesh into the peritoneal cavity. Neodymium magnets on a prototype control arm were used to help position the mesh by magnetically engaging previously placed endoscopic clips. Transfascial fixation of the mesh with 3-0 monofilament sutures was achieved using a 19-gauge hollow needle, pusher wire, and a suture tag system. RESULTS: Composite hernia mesh was successfully transferred and secured in 5/5 attempts. All three survival animals thrived for 14 days prior to elective sacrifice. At necropsy, the mesh sites were found to be well peritonealized without adhesions. Suture placement through the posterior fascia was confirmed in 10/12 sutures. Of these, four sutures were within the abdominal musculature, and two sutures were through the anterior fascia (transfascial). CONCLUSIONS: Transcolonic delivery, transcutaneous magnetic manipulation, and fixation of composite hernia mesh are technically feasible in a porcine model with animal survival. An effective suturing method that allows consistent anchoring through the anterior fascia would be preferred and may require the development of novel devices.

Dual-port distal pancreatectomy using a prototype endoscope and endoscopic stapler: a natural orifice transluminal endoscopic surgery (NOTES) survival study in a porcine model.

BACKGROUND AND STUDY AIMS: Natural orifice transluminal endoscopic surgery (NOTES) is a potentially less invasive alternative to laparoscopic surgery that may be applicable to distal pancreatectomy. We aimed to demonstrate the technical feasibility of a NOTES distal pancreatectomy in an in vivo porcine model via a combined transvaginal-transcolonic approach. MATERIAL AND METHODS: The procedure was performed in five female Yorkshire pigs weighing approximately 30 kg each. A prototype endoscope ("R-scope"), advanced into the peritoneal cavity through an anterior colotomy, and a computer-assisted linear stapler, introduced transvaginally, were used in dissection and resection of the distal pancreas. Prone positioning was used to enhance retroperitoneal exposure. Pneumodissection was used for blunt dissection. The colotomies were closed with endoloops. Necropsies were done immediately after the procedure in the first three animals, and after 2 weeks' survival in the final two animals. RESULTS: Distal pancreatectomy was successful in all five animals. Prone positioning was critically important for proper exposure of retroperitoneal and pelvic structures. Pneumodissection was effective for blunt dissection, and both the linear stapler and R-scope functioned smoothly. Transvaginal and transcolonic access provided similar intraperitoneal views, and the dual-lumen approach enhanced triangulation. Both survival animals thrived postoperatively. Necropsies revealed clean staple lines; closed transcolonic and transvaginal incisions; and absence of infection, hemorrhage, or fluid collections. CONCLUSIONS: NOTES distal pancreatectomy is technically feasible in the porcine model. The transvaginal approach provides a vantage point very similar to that of the transcolonic route and holds promise as a NOTES access site, either singly or as part of a dual-lumen approach. The endoscopic linear stapler and R-scope both advance NOTES capabilities. The novel concepts of fully prone positioning, pneumodissection, and endoloop colotomy closures are introduced. Considering anatomical differences and that healthy animals were used, transferring this technique to patients with pancreatic disease might be difficult and further modifications would likely be needed.

Cetirizine-induce cholestasis.

Cetirizine, a human metabolite of hydroxyzine, is a selective H1-receptor antagonist currently approved for the treatment of seasonal allergic rhinitis, perennial allergic rhinitis, and chronic urticaria. In U.S. clinical trials, transient reversible hepatic transaminase elevations were observed in <2% of patients during cetirizine therapy. We report a case of cetirizine-induced cholestasis in a 28-year-old man with no previous hepatobiliary disease after a 2-year period of taking cetirizine on a daily basis. The treatment of this patient included the use of ursodeoxycholic acid, as well as hydroxyzine, for symptomatic relief of pruritus. In light of the patient's clinical and biochemical improvement while using hydroxyzine, it appears that the hepatic metabolism of hydroxyzine to metabolites, including cetirizine, is not involved in the pathogenesis of this particular case of drug-induced hepatotoxicity. Cetirizine should be considered as a potential cause of drug-induced cholestasis.

The folded conformation of phage P22 coat protein is affected by amino acid substitutions that lead to a cold-sensitive phenotype.

Three cold-sensitive mutants in phage P22 coat protein have been characterized to determine the effects of the amino acid substitutions that cause cold sensitivity on the folding pathway and the conformation of refolded coat protein. Here we find that the three cold-sensitive mutants which have the threonine residue at position 10 changed to isoleucine (T10I), the arginine residue at position 101 changed to cysteine (R101C), or the asparagine residue at position 414 changed to serine (N414S) were capable of folding from a denatured state into a soluble monomeric species, but in each case, the folded conformation was altered. Changes in the kinetics of folding were observed by both tryptophan and bisANS fluorescence. In contrast to the temperature-sensitive for folding coat protein mutants which can be rescued at nonpermissive temperatures in vivo by the overproduction of molecular chaperones GroEL and GroES [Gordon, C. L., Sather, S. K., Casjens, S., & King, J. (1994) J. Biol. Chem. 269, 27941-27951], the folding defects associated with the cold-sensitive amino acid substitutions were not recognized by GroEL and GroES.

Interactions between coat and scaffolding proteins of phage P22 are altered in vitro by amino acid substitutions in coat protein that cause a cold-sensitive phenotype.

Cold-sensitive mutations in phage P22 coat protein cause the accumulation of precursor capsids in cells growing at the nonpermissive temperature (16 degrees C). The assembly of coat proteins which carry the substitutions threonine at position 10 to isoluecine (T10I), arginine at position 101 to cysteine (R101C), or asparagine at position 414 to serine (N414S) which cause cold-sensitivity has been investigated. All three proteins were found to fold into a monomeric species. Coat proteins carrying the amino acid substitutions T10I and R101C were not able to interact with scaffolding protein appropriately to initiate assembly in vitro while coat protein carrying the substitution N414S was able to assemble; however, capsids formed of this protein had an increased affinity for scaffolding protein. These amino acid substitutions define two regions in coat protein that are essential for the interaction of coat protein with scaffolding protein at different stages in capsid maturation.