Predictive Modeling of Tacrolimus Dose Requirement Based on High-Throughput Genetic Screening

Any biochemical reaction underlying drug metabolism depends on individual gene-drug interactions and on groups of genes interacting together. Based on a high-throughput genetic approach, we sought to identify a set of covariant single-nucleotide polymorphisms predictive of interindividual tacrolimus (Tac) dose requirement variability. Tac blood concentrations (Tac C₀ ) of 229 kidney transplant recipients were repeatedly monitored after transplantation over 3 mo. Given the high dimension of the genomic data in comparison to the low number of observations and the high multicolinearity among the variables (gene variants), we developed an original predictive approach that integrates an ensemble variable-selection strategy to reinforce the stability of the variable-selection process and multivariate modeling. Our predictive models explained up to 70% of total variability in Tac C₀ per dose with a maximum of 44 gene variants (p-value <0.001 with a permutation test). These models included molecular networks of drug metabolism with oxidoreductase activities and the multidrug-resistant ABCC8 transporter, which was found in the most stringent model. Finally, we identified an intronic variant of the gene encoding SLC28A3, a drug transporter, as a key gene involved in Tac metabolism, and we confirmed it in an independent validation cohort.

Cdc13 cooperates with the yeast Ku proteins and Stn1 to regulate telomerase recruitment

The Saccharomyces cerevisiae CDC13 protein binds single-strand telomeric DNA. Here we report the isolation of new mutant alleles of CDC13 that confer either abnormal telomere lengthening or telomere shortening. This deregulation not only depended on telomerase (Est2/TLC1) and Est1, a direct regulator of telomerase, but also on the yeast Ku proteins, yKu70/Hdf1 and yKu80/Hdf2, that have been previously implicated in DNA repair and telomere maintenance. Expression of a Cdc13-yKu70 fusion protein resulted in telomere elongation, similar to that produced by a Cdc13-Est1 fusion, thus suggesting that yKu70 might promote Cdc13-mediated telomerase recruitment. We also demonstrate that Stn1 is an inhibitor of telomerase recruitment by Cdc13, based both on STN1 overexpression and Cdc13-Stn1 fusion experiments. We propose that accurate regulation of telomerase recruitment by Cdc13 results from a coordinated balance between positive control by yKu70 and negative control by Stn1. Our results represent the first evidence of a direct control of the telomerase-loading function of Cdc13 by a double-strand telomeric DNA-binding complex.

[Vaginal template implant for cervical carcinoma with vaginal stenosis]

OBJECTIVE

For cervical carcinoma patients with poor geometry for conventional intracavitary radiotherapy, a simple vaginal template for interstitial implantation as a substitute was used. This is a report of the treatment results.

METHODS

Patients with vaginal stenosis were treated over from July 1987 to June 1991 with this vaginal template implant as part of the treatment. The applicator consisted of a front piece and an end piece. Holes were drilled in the front piece to guide the implantation of the cervix or vaginal vault. The diameter of applicators varied from 2.0 cm to 3.5 cm. Depending on the diameter of the applicators, six to eight needles on the periphery, or eight peripheral plus one central needle were used. The activity of the needles were around 8 mCi with a total length of 5.5 cm. The end piece was locked onto the front piece by a bayonet-type locking device. The purpose of the end piece was two-fold: to make up the length of the whole applicator to fit the vagina and to keep the implanted needles in place without being extruded. The implantation was performed under general anesthesia.

RESULTS

One of the twelve patients treated with the vaginal template implant for vaginal stenosis had relapsed centrally but subsequently died of intercurrent disease. Two other patients died of intercurrent disease at 26.2 and 41.9 months, respectively, without evidence of relapse. Nine other patients had been followed with no evidence of local relapse for 23.7 to 54.6 months.

CONCLUSION

This vaginal template implantation is satisfactory in treating cervical carcinoma patients with vaginal stenosis.

Scapholunate advanced collapse wrist salvage

Patients with scapholunate advanced collapse (SLAC) wrist do not have to undergo total wrist arthrodesis; the SLAC pattern spares the radiolunate articulation, providing a basis for salvage. We report the results of 100 cases in which a technique comprised of scaphoid excision and limited wrist arthrodesis was used. The average followup period of 44 months revealed excellent functional status and a high rate of patient satisfaction. The majority of employed patients were able to return to their original jobs, and many chose to resume wrist-related recreational activities. Pain relief was good to excellent in most cases. Extension/flexion averaged 72 degrees (53% of a normal opposite wrist), radioulnar deviation 37 degrees (59%), and grip strength 80% of the opposite side. X-ray films revealed only two instances of radiolunate destruction, both in conjunction with ulnar translation of the carpus. The other 98 patients demonstrated a well-preserved radiolunate joint regardless of followup interval. Complications were few. Nonunion occurred in three cases. A dorsal impingement of the capitate and radius (12%) was felt to be technique-related and avoidable by careful capitolunate alignment.