Anti-inflammation induced by counter-irritation or by treatment with non-steroidal agents inhibits the growth of a tumour of non-detected immunogenicity

Kaurenic acid: An in vivo experimental study of its anti-inflammatory and antipyretic effects

Objective:

This study was designed to investigate the anti-inflammatory and antipyretic effects of kaurenic acid (KA), a tetracyclic diterpenoid carboxylic acid, using in vivo experimental animal models.

Material and Methods:

The anti-inflammatory activity of KA was evaluated in rats, using egg albumin-induced paw edema (acute test) and Freund’s complete adjuvant-induced paw edema (subacute test), whereas the antipyretic effect was studied in rabbits by peptone-induced pyresis. Acute and subacute toxicity of KA were analyzed in NMRI mice.

Results:

KA showed anti-inflammatory and antipyretic properties, and the effect caused was significantly dose-related (P < 0.001) in both cases. The mean lethal doses of KA were 439.2 and 344.6 mg/kg for acute and subacute toxicity, respectively.

Conclusion:

On the basis of these findings, it may be inferred that KA has an anti-inflammatory and antipyretic potential.

A theoretical explanation of "concomitant resistance"

Concomitant resistance is a tumor growth dynamic which results when the growth of a second tumor implant is inhibited by the presence of the first. Recently, we modeled tumor growth in the presence of a regenerating liver after partial hepatectomy (Michelson and Leith, Bull. Math. Biol. 57, 345-366, 1995), with an interlocking pair of growth control triads to account for the accelerated growth observed in both tissues. We also modeled tumor dormancy and recurrence as a dynamic equilibrium achieved between proliferating and quiescent subpopulations. In this paper those studies are extended to initially model the concomitant resistance case. Two interlocking model systems are proposed. In one an interactive competition between the tumor implants is described, while in the other purely proportional growth inhibition is described. The equilibria and dynamics of each system when the coefficients are held constant are presented for three subcases of model parameters. We show that the dynamic called concomitant resistance can be real or apparent, and that if the model coefficients are held constant, the only way to truly achieve concomitant resistance is by forcing one of the tumors into total quiescence. If this is the true state of the inhibited implant, then a non-constant recruitment signal is required to insure regrowth when the inhibitor mass is excised. We compare these theoretical results to a potential explanation of the phenomenon provided by Prehn (Cancer Res. 53, 3266-3269, 1993).

Piroxicam-copper complexes: inhibition of polymorphonuclear leukocyte migration to Pseudomonas aeruginosa chemotactins in vivo and superoxide dismutase-like activity in vitro

Piroxicam-copper (Cu2+) complexes, formed spontaneously by mixing solutions of piroxicam and CuSO4 (1:1 Cu2+:piroxicam), inhibited the superoxide anion-catalyzed reduction of ferricytochrome C in a dose-related fashion. Addition of ethylenediaminetetraacetate to the mixture decreased in a dose-related manner the superoxide dismutase (SOD)-like activity of piroxicam-Cu2+. Piroxicam alone (10(-5) M, final concentration) did not display SOD-like activity but 10(-5) M Cu2+ exhibited significant activity, similar to that of piroxicam-Cu2+. Intraperitoneal treatment of mice with either 0.64 mg/kg piroxicam or its Cu2+ complexes (0.64 mg/kg piroxicam + 0.12 mg/kg Cu2+) was equally effective in diminishing both the migration of polymorphonuclear leukocytes (PMNL) to the airways and the content of myeloperoxidase activity in the lungs, induced by aerosol challenge with Pseudomonas aeruginosa peptide chemotactins. Therefore, piroxicam-Cu2+ complexes may provide both the anti-inflammatory activity of piroxicam plus the SOD-like activity of Cu2+.

Treatment with a non-steroidal anti-inflammatory agent delays the growth of spontaneous pulmonary metastases of a mammary adenocarcinoma of non-detected immunogenicity

Previous reports showed that treatment with non-steroidal anti-inflammatory agents (NSAIA) can alter the growth profile of a variety of tumours. In this study, the effect of NSAIA treatment on the growth of the primary tumour and the appearance of spontaneous pulmonary metastases, was investigated. A mammary adenocarcinoma of non-detected immunogenicity, C7HI, was grafted subcutaneously in the lateral flank of Balb/c mice. Oral treatment with approximately 1 mg kg-1 day-1 piroxicam delayed both tumour growth and the growth of pulmonary metastases. Survival of mice bearing the primary tumour was significantly lengthened by anti-inflammatory treatment. Similarly, in separate experiments, after surgical removal of the primary tumour by day 34 after grafting, the group of mice treated orally with piroxicam also exhibited a higher survival rate than the control group. Upon surgical removal of the primary tumour 34 days after grafting, piroxicam treatment significantly decreased both the number and size of pulmonary metastases. The results of this study lends support to the hypothesis that inhibition or modulation of inflammation may delay tumour organisation and growth. It is suggested that piroxicam treatment may be an appropriate adjunct therapy to delay the appearance of pulmonary metastases and to increase life-expectancy in a host whose primary tumour has to be surgically removed.