Factors predicting subcutaneous implanted central venous port function: the relationship between catheter tip location and port failure in patients with gynecologic malignancies.

OBJECTIVE: We set out to determine the factors that predict subcutaneous implanted central venous port function. Specifically, we sought to determine whether the location of the catheter tip is correlated with port failure. METHODS: A review of all gynecologic oncology patients who underwent initial port placement between 1993 and 1998 was undertaken. The initial chest radiograph following port placement was reviewed, and the venous location of the catheter tip was recorded. Patients were followed until port removal, death, or the last documentation of port function. RESULTS: Two hundred thirty-six patients underwent port placement during the study period. The majority of patients (97%) had their port placed for intravenous chemotherapy. The median time of port duration in patients with a functional port was 21.6 months. Forty of the 236 ports (17%) were removed because of device malfunction. Catheter tips were located in the central venous system in 164 (69%) cases and outside of the central venous system in 72 (31%) cases. Removal secondary to malfunction was significantly higher when the catheter tip was located outside of the central venous system (30/72 (42%) versus 10/164 (6%), P = 0.001). By life-table analysis, ports removed for malfunction with their tips located centrally had a significantly longer median duration of functional use than those whose tips were located peripherally (78 versus 44 months, P = 0.0001). CONCLUSIONS: The rate of port removal secondary to malfunction is significantly less if the catheter tip is located in the central venous system. Confirmation of the location of the catheter tip is imperative for the long-term function of a subcutaneous implanted central venous port.

Melatonin cycle in the fiddler crab Uca pugilator and influence of melatonin on limb regeneration.

Melatonin was measured over 24 hr in the eyestalks of Uca pugilator by means of radioimmunoassay; crabs were acclimatized either to a LD 12:12 photoperiod or constant darkness. A significant peak occurred at 13.00 hr in the LD 12:12 crabs. A photophase peak in melatonin has only been reported in one other species, also a crustacean. In constant darkness, two melatonin peaks occurred, one at 16.00 hr and the other 12 hr later; these results suggest that the melatonin cycle is a true circadian rhythm. HPLC with ultraviolet-visible detection was used to confirm the identity of melatonin immunoactivity. The influence of melatonin on regeneration of the walking legs was also examined: eyestalks were either removed or left intact, and limb bud length was measured every other day for at least 17 days in control and melatonin-treated crabs (60 microg ml(-1) seawater). Melatonin significantly increased the rate of limb regeneration in both eyestalk-intact and eyestalk-removed groups; this is contrary to results of regeneration studies in other phyla, in which similar melatonin concentrations inhibited regeneration.