Sodium ascorbate supplementation in drinking water inhibited subcutaneous tumor growth, enhanced levodopa methylester (LDME) chemotherapy, and increased survival of B16 melanoma-bearing mice. Antitumor activity was greatest in mice fed diets low in tyrosine and phenylalanine (restricted diet). Ascorbate partially protected against LDME-induced decrease in food intake. Primary tumor masses were smaller, more well defined, and less invasive in ascorbate-supplemented mice, and secondary tumor masses appeared encapsulated. Dehydroascorbate increased tumor growth and decreased survival. Ascorbate supplementation did not alter establishment of experimental B16-BL6 melanoma metastases but inhibited tumor outgrowth when combined with LDME chemotherapy and the restricted diet. Spontaneous metastasis was inhibited by ascorbate in mice fed the restricted diet. Ascorbate supplementation doubled plasma concentration in melanoma-bearing mice independent of diet and increased tumor concentration 3.7-fold (basal diet) and 5.6-fold (restricted diet) relative to unsupplemented mice. Tumor peroxidation also increased during ascorbate supplementation and LDME treatment.

Background-The frequency of dietary protein bound vitamin B 12 malabsorption in elderly patients remains controversial. Aims-To evaluate this malabsorption in elderly hospitalised patients using a modified Schilling test. Patients-Fourteen elderly patients with low B 12 blood levels were prospectively selected from 394 hospitalised patients. Methods-The modified Schilling test was performed with trout labelled in vivo.Results-The test was normal in five healthy elderly subjects, in 7/8 patients with pancreatic insuYciency, and in nine non-elderly patients with antral gastritis. The low decision limit was established at 3.3% (median 4.8%). From the 14 elderly patients with low B 12 prospectively selected from 394 hospitalised patients, seven had a real deficiency with anaemia and an increased homocysteine and/or methylmalonate serum level. The modified Schilling test showed malabsorption in five of these patients, including two in which the standard Schilling test was normal, and three in which the standard Schilling test was partially corrected by an intrinsic factor. Conclusions-Protein bound vitamin B 12 malabsorption was detected in at least 0.5% of elderly hospitalised patients, using the labelled trout flesh absorption test. (Gut 1997; 41: 475-479)

There is a growing body of basic science and epidemiologic evidence to support a research thrust to determine whether several natural or synthetic agents, given alone or together, can lower cancer incidence. Candidate agents include analogs of vitamin A and the vitamin A precursor, beta-carotene, vitamins C and E, and the trace metal selenium. Other agents now being studied in the laboratory include phenolic antioxidants, protease inhibitors, prostaglandin synthesis inhibitors, and indoles. Research in chemoprevention involves identifying and characterizing agents with reported activity, efficacy and toxicologic testing to select the most promising agents, and clinical trials to test those with the most potential in humans. Activities are underway in all the above areas, including 24 clinical trials, to evaluate selected compounds in preventing cancer at various cancer sites. Included are studies of individuals at high risk, individuals with precancerous lesions and individuals free of cancer but at risk to second cancers. A number of agents have shown activity in reducing bladder cancer incidence in animal models. The potential applicability of these agents for studies in human cancer risk reduction intervention studies is discussed. Cancer induction is postulated to be a multistage process involving initiation and promotion. Progress in cancer prevention may result from not only reducing exposures to initiators, but also suppressing promotional activity in initiated cells. Newly developed research technologies including cellular, animal, and epidemiologic procedures are being used for identifying, refining, and testing cancer prevention strategies.

The antitumor activity of 2-[bis-(2-chloroethyl)-amino]ethanesulfonic acid (also referred to here as "taurine mustard" or "taumustine") was evaluated in the murine P388 and L1210 lymphocytic leukemias and in the pigmented and nonpigmented B16 melanoma systems. Treatment with a single ip dose of taumustine (40 mg/kg) resulted in a 130% increase in life-span for mice bearing P388 (intraperitoneal), a 93% increase for mice bearing L1210 (intraperitoneal), and an approximately 80% increase for mice bearing B16 melanoma (intraperitoneal). Repeated low doses (10 mg/kg) of taumustine promoted a 250% increase in life-span for mice bearing P388 (intraperitoneal), the absence of ascitic fluid from day 4 onward, and the presence of pulmonary emboli from day 5 onward. The inclusion of taurine (5 mM) in the culture medium of P388 cells in primary culture for 45 hours did not alter the cytotoxicity of taumustine, and pretreatment of the tumor-bearing host with taurine (250 mg/kg) in daily treatments with taumustine for up to 8 days did not interfere with antitumor activity (140-160% increased life-span). However, treatment of tumor-bearing mice with taurine abrogated neurotoxicity, intestinal necrosis, pulmonary emboli formation, and tail vein necrosis due to the administration of taumustine. The modulation by taurine of taumustine activity suggests that the combination of these agents offers an advantage of selectivity and host protection during chemotherapy.