Intron presence-absence polymorphism in Drosophila driven by positive Darwinian selection

Comparisons of intron-exon structures between homologous genes in different eukaryotic species have revealed substantial variation in the number of introns. These observations imply that, in each case, an intron presence-absence polymorphism must have existed in the past. Such a polymorphism, created by a recent intron-loss mutation, is reported here in a eukaryotic organism. This gene structure, detected in the jingwei (jgw) gene, segregates at high frequency (77%) in natural populations of Drosophila teissieri and is associated with a marked change in mRNA levels. Furthermore, the intron loss does not result from a mRNA-mediated mechanism as is usually proposed, but from a partial deletion at the DNA level that also results in the addition of four new amino acids to the JGW protein. Population genetic analyses of the pattern of nucleotide variation surrounding the intron polymorphism indicate the action of positive Darwinian selection on the intron-absent variant. Forward simulations suggest that the intensity of this selection is weak to moderate, roughly equal to the selection intensity on most replacement mutations in Drosophila.     

Intraperitoneal desmoid tumors and polyposis coli (presentation of 2 cases)

Two patients with polyposis coli, developed intraperitoneal desmoid tumours after colectomy. The tumours in both cases, were inoperable. Death occurred in one patient and the other required ileostomy.     

Evolution of biliary complications after liver transplantation: a single European series

Background

The aim of this study was to analyze the evolution of biliary complications over 20 years among adult patients undergoing liver transplantation (OLT) at our institution.

Patients and methods

Between 1985 and 2007, we performed 1000 OLT in 789 adults and 211 children. To ascertain the evolution of biliary complications among adult OLT from October 1988 to September 2007, we compared the first 100 to with the last 200 adult OLT.

Results

Duct-to-duct was the most common biliary anastomosis performed in both periods (1st; 89% and 2nd; 94%; P = NS). However, a T-tube was used more frequently in the first period (1st; 46% vs 2nd; 6.6%; P < .001). The remaining cases underwent a hepaticojejunostomy (1st; 11% vs 2nd; 7.6%). Biliary complications were more frequent in the first period (1st; 20% vs 2nd; 9%; P < .01). In the first period, the use of a T-tube caused 32% of complications, all of them being bile leaks; but there were none in the second period. Arterial thrombosis or strictures were related to biliary complications in 10% and 33.3% among the first and second periods, respectively. The severity of complications according to the Clavien classification was similar in both periods: IIIa, 15% versus 33.3%; IIIb, 55% versus 55.5%; and IV, 15% versus 11.1%, respectively (P = NS).

Conclusion

The biliary complication rate among adult patients post-OLT decreased over 20 years at our institution, probably owing to the abandonment of the routine use of a T-tube as well as to advances in immunosuppressive protocols, organ preservation, and preoperative patient management.     

Perforation of the pharynx caused by blunt external neck trauma

We present two cases of a rare entity: pharyngeal perforation caused by blunt external neck trauma. In both cases the patients were asymptomatic for the first 24 h and the results of laryngoscopic study were negative, and it was only possible to demonstrate rupture through the radiologic findings. Early diagnosis is essential as delay in treatment increases morbidity and mortality. Received 21 June 1996; Revision received 30 December 1996; Accepted 9 April 1997