A Markov chain Monte Carlo strategy for sampling from the joint posterior distribution of pedigrees and population parameters under a Fisher-Wright model with partial selfing.

A simple population genetic model is presented for a hermaphrodite annual species, allowing both selfing and outcrossing. Those male gametes (pollen) responsible for outcrossing are assumed to disperse much further than seeds. Under this model, the pedigree of a sample from a single locality is loop-free. A novel Markov chain Monte Carlo strategy is presented for sampling from the joint posterior distribution of the pedigree of such a sample and the parameters of the population genetic model (including the selfing rate) given the genotypes of the sampled individuals at unlinked marker loci. The computational costs of this Markov chain Monte Carlo strategy scale well with the number of individuals in the sample, and the number of marker loci, but increase exponentially with the age (time since colonisation from the source population) of the local population. Consequently, this strategy is particularly suited to situations where the sample has been collected from a population which is the result of a recent colonisation process.

Inadvertent discontinuation of percutaneous nephrostomy catheters in adult native kidneys: incidence and percutaneous management.

PURPOSE: To evaluate the incidence and consequences of complete inadvertent percutaneous nephrostomy catheter discontinuation in native kidneys of adults. In addition, this study evaluated the success rate of nephrostomy tract recannulation. MATERIALS AND METHODS: Retrospective analysis was performed in adult patients who underwent percutaneous nephrostomy between January 2000 and December 2005. Patients' conditions were evaluated for complete inadvertent discontinuation of use of the nephrostomy catheters and success of subsequent recannulation procedures. Habitual discontinuation was defined by three catheter discontinuation episodes in one patient. Conditions of patients with inadvertent discontinuation were assessed for major complications before and after the recannulation, including the need for de novo nephrostomy to reestablish clinically needed access. The incidences of inadvertent discontinuation and primary assisted recannulation tract maintenance were calculated according to the Kaplan-Meier method. Successful versus unsuccessful recannulation procedures were compared for tract age, length of time the drain was out of the tract, and catheter diameter with use of the Mann-Whitney U test. RESULTS: A total of 283 patients underwent 325 percutaneous nephrostomies. The inadvertent catheter discontinuation rates at 6, 12, 24, and 36 months were 26%, 36%, 53%, and 62%, respectively. For the same time intervals, the primary recannulation assisted tract maintenance rates were 94%, 86%, 77%, and 72%, respectively. Habitual discontinuation was seen in 3.2% of the total population and 19.1% of discontinuation cases. The technical success rates of all and first-time recannulations were 85% and 74%, respectively. Tract maturity was the only variable that was statistically significant between successful and unsuccessful recannulations (P < .0001). A total of 3.5% of patients required new nephrostomies. CONCLUSION: Despite the high incidence of inadvertent discontinuation of nephrostomy catheters, the major complication rate was only 3.5%, indicating the efficacy of tract recannulation, especially in mature tracts.