Cytotoxic effects of current dental adhesive systems on immortalized odontoblast cell line MDPC-23.

OBJECTIVES: Evaluate the cytotoxic effect of the three dental adhesive systems. METHODS: The immortalized mouse odontoblast cell line (MDPC-23) was plated (30,000 cell/cm2) in 24 well dishes, allowed to grow for 72 h, and counted under inverted light microscopy. Uncured fresh adhesives were added to culture medium to simulate effects of unset adhesive. Three adhesives systems were applied for 120 min to cells in six wells for each group: Group 1) Single Bond (3M), Group 2) Prime & Bond 2.1 (Dentsply), and Group 3) Syntac Sprint (Vivadent). In the control group, PBS was added to fresh medium. The cell number was counted again and the cell morphology was assessed under SEM. In addition, the adhesive systems were applied to circles of filter paper, light-cured for 20 s, and placed in the bottom of 24 wells (six wells for each experimental materials and control group). MDPC-23 cells were plated (30,000 cell/cm2) in the wells and allowed to incubate for 72 h. The zone of inhibition around the filter papers was measured under inverted light microscopy; cell morphology was evaluated under SEM; and the MTT assay was performed for mitochondrial respiration. RESULTS: The fresh adhesives exhibited more toxic (cytopathic effects) to MDPC-23 cells than polymerized adhesives on filter papers, and as compared to the control group. The cytopathic effect of the adhesive systems occurred in the inhibition zone around the filter papers, which was confirmed by the MTT assay and statistical analysis (ANOVA) combined with Fisher's PLSD test. In the control group, MDPC-23 cells were dense on the plastic substrate and were in contact with the filter paper. In the experimental groups, when acid in the adhesive systems was removed by changing the culture medium, or when the adhesives were light-cured, some cells grew in the wells in spite of the persistent cytotoxic effect. SIGNIFICANCE: All dentin adhesive systems were cytotoxic odontoblast-like cells. Both acidity and non-acidic components of these systems were responsible for the high cytopathic effect of those dental materials.

Suppression of human colorectal mucosal prostaglandins: determining the lowest effective aspirin dose.

BACKGROUND: A variety of studies have supported the finding that regular intake of aspirin (acetylsalicylic acid) or nonsteroidal anti-inflammatory agents can affect colorectal cancer carcinogenesis. These agents inhibit the synthesis of prostaglandins. High levels of prostaglandins are observed in colon cancer tissues. PURPOSE: Experiments were planned to determine the lowest dose of aspirin that can markedly suppress the levels of mucosal prostaglandins E2 and F(2alpha) in colorectal mucosa and to determine whether a relationship exists between these levels and plasma levels of both acetylsalicylic acid and its metabolite, salicylic acid. METHODS: Healthy men and women aged 18 years or older participated in the study. The participants took a single, daily dose of aspirin (40.5, 81, 162, 324, or 648 mg) or a placebo for 14 days. Colorectal biopsy specimens were taken at baseline, 24 hours after the first dose of aspirin, and 24-30 hours and 72-78 hours after the last, i.e., fourteenth, daily dose of aspirin. The biopsy specimens were assayed for prostaglandins E2 and F(2alpha) by use of a competitive enzyme immunoassay. Plasma concentrations of acetylsalicylic acid and salicylic acid were determined by use of high-performance liquid chromatography. All P values are two-sided. RESULTS: A total of 65 subjects (10 receiving placebo, groups of 10 each receiving 40.5, 81, 162, or 324 mg of aspirin, and a group of 15 receiving 648 mg of aspirin) completed the protocol. One subject reported unacceptable drug-induced toxic effects and did not complete the protocol; other subjects reported acceptable side effects. The lowest dose to significantly suppress colorectal mucosal prostaglandin E2 concentrations from baseline at 24 hours after the first dose (by 22.6%; P = .002) and at 24-30 hours after the last dose (by 14.2%; P = .021) was 162 mg. At 72-78 hours after the last dose, there was significant suppression for subjects receiving 81 mg (by 23.7%; P = .008). The lowest dose to significantly suppress colorectal mucosal prostaglandin F(2alpha) concentrations from baseline at 24 hours after the first dose (by 18.3%; P = .032) was 324 mg. The lowest dose causing a marked reduction in the level of prostaglandin F(2alpha) at 24-30 hours (by 15.1%; P = .003) and 72-78 hours (by 23.0%; P = .0002) after the last dose was 40.5 mg. No detectable amounts of acetylsalicylic acid or salicylic acid were present in the plasma at any of the biopsy time points. CONCLUSIONS: The lowest doses of aspirin taken daily for 14 days to significantly suppress concentrations of colorectal mucosal prostaglandins E2 and F(2alpha) were 81 and 40.5 mg, respectively. The suppression occurred without detectable amounts of aspirin or salicylic acid in the plasma at the time points studied. On the basis of these observations, we recommend a single, daily dose of 81 mg of aspirin in future studies of this drug as a chemopreventive agent for colorectal cancer.

Pharmacokinetic evaluation of percutaneous hepatic venous isolation for administration of regional chemotherapy.

Hepatic artery infusion (HAI) chemotherapy has been used to treat patients with unresectable liver tumours. We report a preclinical study of the pharmacokinetics of HAI combined with hepatic venous drug extraction (HVDE) for regional administration of doxorubicin. HVDE was aided by a double balloon catheter inserted via femoral vein cutdown into the inferior vena cava to collect all hepatic vein blood. Pigs received doxorubicin 0.5-9.0 mg kg-1 over 90 min via HAI or systemic infusion (SYSI). HVDE was performed for 240 min. SYSI pigs underwent hepatic venous isolation without drug filtration. Doxorubicin levels were assayed using high-pressure liquid chromatography (HPLC). HAI/HVDE reduced systemic exposure to doxorubicin with equivalent hepatic exposure at all doses. Pharmacokinetic enhancement ranged from 7.0 to 22.3 for peak concentration, 8.8-23.2 for the area under the curve and 2.9-4.2 for tissue concentration. HAI/HVDE also prevented the mortality which was observed with SYSI administration of high-dose (5.0 and 9.0 mg kg-1) doxorubicin. We conclude that HAI/HVDE reduces systemic exposure to doxorubicin as compared with SYSI of equivalent doses. Pharmacokinetic enhancement indices suggest that HAI/HVDE may allow equivalent hepatic drug exposure with reduced systemic exposure. This method may be applicable to other drugs and to other anatomic settings in which enhanced regional drug delivery is desirable.

Hepatic artery infusion of doxorubicin with hepatic venous drug extraction.

Hepatic artery infusion (HAI) has been used to take advantage of the steep dose-response relationship characteristic of chemotherapeutic agents. Systemic toxicity, however, remains the dose limiting factor for HAI of low hepatic extraction drugs. This investigation compared the pharmacokinetics of doxorubicin administered using a system that combines HAI and hepatic venous drug extraction (HVDE) versus systemic administration without HVDE. HAI was accomplished by transfemoral cannulation of the hepatic artery. HVDE was aided by use of a double-balloon catheter inserted fluoroscopically via femoral vein cutdown into the inferior vena cava. Inflation of the balloons above and below the hepatic veins allowed collection of hepatic venous effluent. Hepatic venous blood was pumped through the double-balloon catheter into an extracorporeal circuit with activated carbon filters to extract drug prior to return to the systemic circulation. Domestic female swine (25-35 kg) received 3 mg/kg doxorubicin over 90 min via HAI. HVDE was performed for 240 min following initiation of HAI (Time 0-240 min). Control swine underwent hepatic venous isolation using the double-balloon catheter without drug filtration and received 3 mg/kg doxorubicin over 90 min via systemic vein (SYSI). Serum and myocardial doxorubicin and doxorubicinol levels were assayed using HPLC. Blood was serially sampled from hepatic vein blood, from the extracorporeal circuit after filtration, and from a systemic artery. Area under the curve (AUC) was integrated from time-concentration plots over Time 0-180 min.(ABSTRACT TRUNCATED AT 250 WORDS)