Differentiating salmon populations at broad and fine geographical scales with microsatellites and single nucleotide polymorphisms.

Single nucleotide polymorphisms (SNPs) are appealing genetic markers due to several beneficial attributes, but uncertainty remains about how many of these bi-allelic markers are necessary to have sufficient power to differentiate populations, a task now generally accomplished with highly polymorphic microsatellite markers. In this study, we tested the utility of 37 SNPs and 13 microsatellites for differentiating 29 broadly distributed populations of Chinook salmon (n = 2783). Information content of all loci was determined by In and G'(ST), and the top 12 markers ranked by In were microsatellites, but the 6 highest, and 7 of the top 10 G'(ST) ranked markers, were SNPs. The mean ratio of random SNPs to random microsatellites ranged from 3.9 to 4.1, but this ratio was consistently reduced when only the most informative loci were included. Individual assignment test accuracy was higher for microsatellites (73.1%) than SNPs (66.6%), and pooling all 50 markers provided the highest accuracy (83.2%). When marker types were combined, as few as 15 of the top ranked loci provided higher assignment accuracy than either microsatellites or SNPs alone. Neighbour-joining dendrograms revealed similar clustering patterns and pairwise tests of population differentiation had nearly identical results with each suite of markers. Statistical tests and simulations indicated that closely related populations were better differentiated by microsatellites than SNPs. Our results indicate that both types of markers are likely to be useful in population genetics studies and that, in some cases, a combination of SNPs and microsatellites may be the most effective suite of loci.

Segment III cholangiojejunostomy for palliation of malignant hilar obstruction.

Between 1984 and 1992, 26 patients with obstructive jaundice due to malignancy at the liver hilum were treated by segment III Roux-en-Y cholangiojejunostomy. Twenty-two patients had hilar cholangiocarcinoma, one carcinoma of the gallbladder, one pancreatic carcinoma, one recurrent gastric carcinoma and one lymphoma. Seventeen patients had no complications in the postoperative period and six had complications; there were three postoperative deaths. Eighteen of the 23 surviving patients experienced complete resolution of jaundice for at least 3 months. Four developed recurrent jaundice and three had episodes of cholangitis before death. Segment III cholangiojejunostomy offers effective palliation for most patients with irresectable hilar malignancy.

Changing trends in the management of extrahepatic cholangiocarcinoma.

A series of 107 patients with cholangiocarcinoma diagnosed between January 1980 and December 1991 is reported. Changing patterns of investigation and treatment in the periods 1980-1985 and 1986-1991 are analysed. There was a decrease in the use of percutaneous transhepatic cholangiography in the second period (86 versus 51 per cent of patients) but increased use of endoscopic retrograde cholangiography (19 versus 71 per cent) and computed tomography (8 versus 59 per cent). The overall resectability rate (17 per cent) was similar to those of other reported series but greater in the second period (8 versus 21 per cent). Palliation by endoscopic and percutaneous stenting was associated with a high incidence of recurrent cholangitis (55 per cent) and jaundice (35 per cent). During the second 6-year period, more effective palliation was achieved by segment III cholangiojejunostomy with a lower incidence of recurrent cholangitis (19 per cent) and jaundice (19 per cent). Overall prognosis for patients with this condition is grim and efforts must usually be aimed at providing the most appropriate palliation.

Abscess formation as a complication of chickenpox.

Chickenpox is a common infectious disease of childhood. Skin lesions may occasionally become secondarily infected with bacteria. Large abscess formation is reported complicating a mild case of chickenpox in a previously healthy patient.

Transcatheter hepatic arterial therapy for symptomatic liver malignancy.

Transcatheter hepatic arterial chemoembolization was performed in ten patients with symptomatic unresectable liver malignancy. Nine patients experienced control of symptoms for 52-100% of the duration of their survival, although one patient died 10 days after the procedure. No objective evidence of decrease in tumour size was seen at review but three cases showed selective decrease in tumour vasculature or tumour necrosis.