Protein engineering methods applied to membrane protein targets.

Genes encoding membrane proteins have been estimated to comprise as much as 30% of the human genome. Among these membrane, proteins are a large number of signaling receptors, transporters, ion channels and enzymes that are vital to cellular regulation, metabolism and homeostasis. While many membrane proteins are considered high-priority targets for drug design, there is a dearth of structural and biochemical information on them. This lack of information stems from the inherent insolubility and instability of transmembrane domains, which prevents easy obtainment of high-resolution crystals to specifically study structure-function relationships. In part, this lack of structures has greatly impeded our understanding in the field of membrane proteins. One method that can be used to enhance our understanding is directed evolution, a molecular biology method that mimics natural selection to engineer proteins that have specific phenotypes. It is a powerful technique that has considerable success with globular proteins, notably the engineering of protein therapeutics. With respect to transmembrane protein targets, this tool may be underutilized. Another powerful tool to investigate membrane protein structure-function relationships is computational modeling. This review will discuss these protein engineering methods and their tremendous potential in the study of membrane proteins.

[Laparoscopic surgery of recurrent hernias after prosthesis (35 cases)]. / Chirurgie laparoscopique des récidives herniaires après prothèse (35 cas).

We report 35 cases of laparoscopic repair after prosthesis surgery using the classic open technique (19 cases) or laparoscopic technique (16 cases). Most difficulties were observed after intraperitoneal laparoscopy. Hernia repair was preferentially intrapreperitoneal (31 cases). Post-operative morbidity was low with two cases of serohematic effusion treated by puncture. Mean hospital stay was 2.5 days. Patients returned to normal activity within 7 days but work stoppage in active patients depended more on patient motivation than the initial surgical procedure. There were no reiterative recurrences although follow-up is too short (mean 21.2 months) for definitive results.

[Laparoscopic resection-anastomosis in diverticular sigmoiditis and its complications apropos of 65 cases]. / La résection anastomose coeliochirurgicale dans la sigmoïdite diverticulaire et ses complications à propos de soixante-cinq cas.

From 1992 to 1995, 77 cases of diverticular sigmoiditis were treated laparoscopically. Conversion to open surgery was required in only 6 cases. There were 27 cases with perforated sigmoid including 5 with peritonitis. Leakages from the anastomosis occurred intraoperatively in 3 cases and were repaired laparoscopically. Early complications were fistulae (n = 2.3%), occlusion by loop agglutination (n = 1) and Richter's hernia (n = 1). A cerebral vascular event lead to death in one patient over 80. Late complications were limited to extensible anastomotic diaphragms (27%) as no true stenoses were observed. There was 1 occlusion on bride and 1 eventration through the extraction orifice. Both were treated laparoscopically. Our overall results after laparoscopic treatment of diverticular sigmoiditis show a 3-fold increase in operative time over classical surgery without any modification in operative risks, a 2-fold reduction in intensive care after surgery and preserved parietal wall (10-fold reduction in the number of eventrations and to a lesser extent fewer occlusions). Laparoscopic surgery does however have its limitations in major peritoneo-occlusive syndromes and in patients with a high risk for anesthesia.

[Primary resection-anastomosis in perforated diverticular sigmoiditis. Apropos of 58 cases of peritonitis, 31 of them generalized]. / La résection-anastomose d'emblée dans les sigmoïdites diverticulaires perforées. A propos de cinquante-huit péritonites dont trente et une généralisées.

Fifty-eight cases of peritonitis due to perforated sigmoid diverticulitis observed over a period of 10 years were treated by emergency mechanical resection-anastomosis without any post-operative anastomotic complication with a mortality in 2 cases (4%). An early operation with large resection and suture as far as possible from the initial focus give results similar to those of a regular anastomosis. The degree of peritoneal affect and especially the general state of health can impose limits to colectomy in the emergency situation. In the light of the results obtained, the use of the circular stapler with the triple stapling technique is now recommended without any particular protection of the suture.