Chemoselective Dimerization of Phosphates.

A methodology for the synthesis of oligophosphate conjugates using phosphordiamidites is described. This strategy facilitates the straightforward preparation of C2-symmetric dinucleoside tri-, penta-, and heptaphosphates. Moreover, unsymmetric compounds such as thiamine adenosine triphosphate and thiamine cytidine triphosphate can be prepared. The material is used to study the inhibitory activity of thiaminylated nucleotides against adenosine diphosphate ribosyltransferases.

Switching to sirolimus monotherapy for de novo tumors after liver transplantation. A preliminary experience.

BACKGROUND/AIMS: Alcoholic cirrhosis, smoking, and use of calcineurin inhibitors (CNI) are associated with the development of de novo tumors in liver transplant (LT) recipients. Sirolimus is an immunosuppressor with antitumoral properties. METHODOLOGY: Between April 1986 and April 2007, we performed 1231 liver transplants in 1084 recipients. A total of 128 de novo tumors were observed in 116 recipients from a sample of 850 adult recipients who survived more than 2 months. This study comprises 16 LT recipients (13 male and 3 female; mean age, 45.1 +/- 11.1 years) who were switched to sirolimus monotherapy who developed de novo tumors and were switched from CNI or mycophenolate mofetil to sirolimus monotherapy. RESULTS: De novo tumors location: 2 lymphomas, 9 upper aerodigestive, 1 skin, 1 parotid, 1 lung, 1 breast, and 1 rectum. Time from LT to sirolimus monotherapy was 86 months; time taking to switching from CNI to sirolimus monotherapy was 48 days, and mean follow-up of patients on sirolimus monotherapy was 15.7 months. Thirteen patients underwent tumor resection, 5 received chemotherapy, and 5 received radiotherapy. Five patients died during the follow-up, and patient survival after diagnosis was 42.8 months. Mean dose of sirolimus was 2.7 mg/day and the mean trough level was 8.9 ng/mL. Total cholesterol and triglycerides values increased after switching. Mean serum creatinine, glucose, AST and ALT values, and haematological parameters were similar before and after switching. No patients developed acute rejection, and adverse effects were observed in 8 patients. CONCLUSIONS: Sirolimus monotherapy can be used safely to improve survival in LT recipients with de novo tumors.

Incidence and risk factors for the development of lung tumors after liver transplantation.

Tobacco and immunosuppression are risk factors for developing upper aerodigestive and lung tumors after transplantation. This study comprises 701 adult recipients who survived more than 2 months after transplant: 276 patients underwent orthotopic liver transplantation (OLT) for alcoholic cirrhosis (AC) and 425 for nonalcoholic disease. The aim is to analyze the incidence, clinical characteristics, risk factors, and outcome of patients who develop lung malignancies after OLT. Incidence of lung cancer was 2.1% (15 patients): 4.3% (12 patients) in the alcoholic group and 0.7% (three patients) in the nonalcoholic group (P < 0.001). Mean time from OLT to tumor diagnosis was 86 months. Thirteen patients were smokers; 12 patients were heavy drinkers; and 11 were drinkers and smokers. Squamous cell carcinoma was diagnosed in nine patients, large cell carcinoma in three, adenocarcinoma in two, and broncoalveolar in one. Tumor staging: 10 patients at stage IV; three at stage IIIB; and two at stage IIB. Tumor resection was performed in one patient, and three also received chemotherapy. Mean survival after tumor diagnosis was 5.4 months. There is a higher risk of lung cancer in smoker patients who have undergone OLT for AC, and have a very poor prognosis because tumors are diagnosed at advanced stages.