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Age-related changes in the nitric oxide-producing neurons in the rat rectoanal region were studied with reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and morphometry. In 15-dayold rats the myenteric plexus of the distal rectum and anal canal, situated in the space between the longitudinal and circular muscle layers, was exposed by NADPH-d positive perikarya. In the anal canal the positive myenteric neurons were more intensively stained than in the rectum. The mean optical density (OD) of positive neurons in the rectum was 115.8±2.4 vs. 89.5±1.6 in the anal canal. Single nerve fibres and small nerve bundles in the circular muscle layer of the anal canal were frequently seen and were more intensively stained than rectal fibres. In 3-month-old rats a larger number of NADPH-d-positive nerve fibres and an increase in their staining intensity were found. The staining intensity of the perikarya in the anal canal was higher than in the rectum (the OD 70.9 ± 1.1 vs. 55.5 ± 1.5). In the circular muscle layer thicker nerve strands were observed. In 26-month-old rats the staining intensity of NADPHd-positive perikarya in the myenteric plexus was weaker than in the 3-month-old rats. In the rectum their OD was lower than in the anal canal (93.8 ± 2.05 vs. 78.9 ± 1.7). The nerve strands were sparse and less intensely stained than in 3-month-old rats. Our results are consistent with the hypothesis that NO is an important neurotransmitter of the recto-anal motility in the ageing gut.

Background/Aims: To gain maximal effectiveness while decreasing toxicity by giving 5-fluorouracil for 45 minutes starting just within 5 minutes after the completion of radiotherapy thrice weekly. Methodology: Thirty-eight patients with locally advanced rectal cancer were enrolled in the study. Ranges of total radiation doses were between 50.4 Gy and 61.2 Gy with a median of 59.4 Gy with fraction size of 1.8 Gy five times weekly. 5-fluorouracil was administered thrice weekly with the dose of 250300mg/m(2)/day concomitantly with radiation therapy. Results: Median follow-up time was 30 months. Administration of chemotherapy concomitant with radiotherapy (p=0.089), AJCC stage III (p=0.079), Duke's stage C (p=0.079), presence of lymph node involvement (p=0.079) and presence of local recurrence (p=0.066) appeared to be effecting distant metastasis although differences did not reach statistically significance. Mean overall survival was 46 months in patients without any distant metastasis (SD: 3.28; 95% CI: 39.46 and 52.31) while it was 35 months in patients with distant metastasis (SD: 5.71; 95% CI: 23.52 and 45.90, p = 0.0 16). Conclusions: Our results have provided further evidence of the ability of postoperative chemoradiotherapy to delay and prevent local recurrence and metastasis of rectal cancer.