Mre11 exonuclease activity removes the chain-terminating nucleoside analog gemcitabine from the nascent strand during DNA replication.

The Mre11 nuclease is involved in early responses to DNA damage, often mediated by its role in DNA end processing. MRE11 mutations and aberrant expression are associated with carcinogenesis and cancer treatment outcomes. While, in recent years, progress has been made in understanding the role of Mre11 nuclease activities in DNA double-strand break repair, their role during replication has remained elusive. The nucleoside analog gemcitabine, widely used in cancer therapy, acts as a replication chain terminator; for a cell to survive treatment, gemcitabine needs to be removed from replicating DNA. Activities responsible for this removal have, so far, not been identified. We show that Mre11 3' to 5' exonuclease activity removes gemcitabine from nascent DNA during replication. This contributes to replication progression and gemcitabine resistance. We thus uncovered a replication-supporting role for Mre11 exonuclease activity, which is distinct from its previously reported detrimental role in uncontrolled resection in recombination-deficient cells.

Investigation of anal sphincter function following Mainz pouch type II urinary diversion after radical cystectomy.

PURPOSES: Our aim was to evaluate the anal sphincter function following cystectomy with urinary diversion of Mainz pouch II. METHODS: Seventy-six patients were involved in our survey, and the cohort was for two groups divided. The first group was a retrospective review of 40 patients with examination of the state of continence. Comparative examinations on anal sphincter function and the quality of life survey were carried out. The second group consisting of 15 patients underwent a prospective investigation including rectal manometry in both the pre- and postoperative periods. Measurements of resting anal sphincter pressure (RASP), maximal anal closing pressure (MACP) and the function of the recto anal inhibitions reflex were taken. RESULTS: In the first part of our investigation, 80% of the patients were considered as continent. There were no significant differences observed between RASP values in the cases of continent as well as of incontinent patients (79.2 ± 2 vs. 73.6 ± 68.4 mmHg, p = 0-53); however, the MACP values of the continent patients were significantly higher (204.3 ± 22.8 vs. 117.3 ± 14 mmHg, p = 0.001). In the course of the second experiment, both the RASP (86.3 ± 18.7 vs. 76.1 ± 13.9 mmHg p = 0.0049) and the MACP (232.2 ± 53.8 vs. 194.1 ± 74.5 mmHg, p = 0.0054) were detected as decreasing in the case of the incontinent group. CONCLUSIONS: A decrease in rectal sphincter function is responsible for incontinence following Mainz pouch type II diversion, and this dysfunction can be correlated with the surgery. Ureterosigmoideostomy is therefore considered as a useful method of urinary diversion only in selected cases with proven good sphincter function.

Bladder augmentation with detubularized intestinal segment.

The authors report on 9 cases of bladder augmentation with detubularized intestinal segments. The capacity of the contracted bladder was increased in 4 cases; care was taken to prevent the development of an hour-glass bladder. In a young female patient a caecal-ileal segment was applied so that in case of a possible future pregnancy the mesentery should not hinder the growth of the uterus. In 4 cases hypertonic neurogenic bladders were augmented with intestinal segments, thus the further destruction of the kidneys could be avoided. In one case the reflux was hindered by a Kock valve, but stagnation developed above the valve, therefore it was eliminated and replaced by a 15 cm intestinal segment. In one case the uninhibited neurogenic bladder was augmented, the resistance of the urethra increased as a result of which the patient stayed dry between self-catheterizations. Attention is called upon the metabolic disturbances and increased risk of infection following intestinal implantations.