Characteristics of draft tube gas-liquid-solid fluidized-bed bioreactor with immobilized living cells for phenol degradation.

Biological phenol degradation in a draft tube gas-liquid-solid fluidized bed (DTFB) bioreactor containing a mixed culture immobilized on spherical activated carbon particles was investigated. The characteristics of biofilms including the biofilm dry density and thickness, the volumetric oxygen mass transfer coefficient, and the phenol removal rates under different operating conditions in the DTFB were evaluated. A phenol degradation rate as high as 18 kg/m(3)-day with an effluent phenol concentration less than 1 g/m(3) was achieved, signifying the high treatment efficiency of using a DTFB.

Combination vincristine and VP-16-213: evaluation of drug sequence.

The combination of vincristine and VP-16-213 has been found to have synergistic antitumor activity in a murine system in vivo when the sequence of drug administration was vincristine followed by VP-16-213. To investigate the potential influence of drug scheduling on this synergistic combination, the reverse sequence of drug administration was evaluated. DBA/2 mice were inoculated with 10(6) P-388 murine leukemia cells, after which saline only, VP-16-213 only, vincristine only, or VP-16-213 followed at various time intervals by vincristine, were administered. Probable cure (survival greater than 60 days) was observed in 0/20, 0/20, 0/120, and 46/115 (40%), respectively (p less than 0.001). The proportion of animals attaining probable cure was greatest in the group receiving vincristine 4-72 hours after VP-16-213 (40-50%). Similar results had been obtained previously with the reverse drug sequence. In this animal model, the synergistic antitumor activity of vincristine and VP-16-213 does not appear to be schedule-dependent with respect to the sequence of drug administration.

Glutamic acid modification of vincristine toxicity.

The principal limiting feature of the antitumor agent, vincristine, in the clinic has been neurotoxicity; there are no known agents which can routinely prevent or decrease this side effect. Glutamic acid in laboratory and clinical investigations in the early 1960s was found to antagonize vinblastine, another clinically useful vinca alkaloid. Glutamic acid 250 mg/kg/d i.p. was given to normal mice treated with repetitive doses of vincristine 1.5 mg/kg every other day. When glutamic acid was given both before and during vincristine administration, it produced a 49-79% increase in survival compared to control mice receiving vincristine only (p less than 0.01). Other schedules of glutamic acid administration were ineffective. Also, there appeared to be a delay in development of neurotoxic manifestations (toe-walking gait) but the results were not as consistent as the improvement in survival. Glutamic acid given to tumor-bearing mice (P-388 and P-1534 murine leukemia) did not inhibit the antitumor effect of vincristine-induced host toxicity in a schedule-dependent fashion without inhibition of the antitumor effect of vincristine.

Synergistic antitumor activity of vincristine and VP-16-213.

The potential interaction of the antitumor agents vincristine and VP-16-213 was investigated in vivo. DBA/2 mice were inoculated with 10(6) P388 murine leukemia cells, after which single IP injections of saline only, vincristine only, VP-16-213 only, or a combination of vincristine and VP-16-213 were administered. Long-term survival (greater than 60 days) was observed in 0/45, 1/45 (2%), 9/135 (7%), and 44/135 (33%) mice, respectively (P less than 0.001). Treatment was most effective when VP-16-213 was administered 0-72 h after vincristine. A similar trend was observed in mice bearing P1534 murine leukemia. These data demonstrate synergistic antitumor activity between vincristine and VP-16-213 in a murine model.

Hepatic intra-arterial infusion of vincristine.

Currently the chemotherapeutic agents available for intra-arterial infusion in metastatic liver cancer are limited to only a few. The recent demonstration of the feasibility of prolonged IV infusion of vincristine led to exploration of hepatic intra-arterial infusion of this agent. A continuous infusion of 0.4 mg total dose was administered daily for 5 days via a hepatic artery catheter to each of six patients with metastatic liver cancer. Transient but life-threatening toxicity principally involving the nervous and gastrointestinal systems occurred in five of them. Future investigation of hepatic intra-arterial infusion of vincristine should be based on dose-schedules other than that employed in the current trial.

Pharmacokinetics of vindesine bolus and infusion.

The pharmacokinetics of vindesine were investigated during treatment of 15 patients with progressive malignancies refractory to conventional treatment. Patients were administered one of three IV dose schedules: 3.0 mg/m2 bolus injection, 1.2 mg/m2/day infusion for 5 days, or 2.0 mg/m2/day infusion for 2 days. Concentrations of the drug in the serum and urine were determined by radioimmunoassay. Serum concentrations were highest (5 X 10(-7) M) in patients receiving a bolus injection, but fell to nondetectable levels by 48 h in four of five patients (terminal t1/2 15.0 +/- 9.4 h). Compared with bolus injection, 1.2- to 1.4-fold greater areas under the blood concentration curve were observed during infusions of 2.0 mg/m2 and 1.2 mg/m2. Whereas steady-state concentrations (approximately 1 X 10(-8) M) were maintained throughout the infusion of 1.2 mg/m2/day progressively increasing serum levels were observed during the infusion of 2.0 mg/m2/day. Serum concentrations fell rapidly following discontinuation of the 2.0-mg/m2 infusion, but were somewhat more sustained in the 1.2-mg/m2 infusion group. The average urinary excretion was similar for each dose-schedule (8%-11% of the total dose). The pharmacokinetics of vindesine are influenced by variations in dose schedule.

Continuous intravenous infusion of vinca alkaloid using a subcutaneously implanted pump in a canine model.

A major drawback of infusions of the vinca alkaloids is the lengthy period of hospitalization which is often required for this novel technique of cancer therapy. A potentially useful system to deliver outpatient therapy has been investigated in a preclinical study. A self-contained infusion pump powered by a self-charging fluorocarbon system has been implanted SC in three dogs. The performance of two pumps which had been factory-calibrated to deliver 2.5 and 4.5 ml/day, respectively, was evaluated during 22 infusions of the vinca alkaloids (vincristine, 7; vinblastine, 7; and vindesine, 8). Infusions were given over a 5- to 7-day period and were repeated at 3-week intervals. No malfunctioning of the pumps occurred in over 500 cumulative days of use. The flow rates of the pumps were quite stable except in one animal whose increased flow rate was probably a consequence of fever due to self-induced inflammation about the pump pocket. No local or distant tissue reactions to the pump were observed. Decomposition of vincristine and vinblastine in the infusate at the end of 5- or 7-day infusions was minimal as determined by high-pressure liquid chromatography. The amount of decomposition of vindesine in the infusate was variable. Steady-state concentrations of vincristine during infusion were always greater than 10(-9) M, and were similar to those previously determined in our clinical infusion trials using a dosage of 0.5 mg/m2/day. Clinical evaluation of this system for prolonged infusions of vincristine and other vinca alkaloids appears to be warranted.