Inflammatory mediators stimulate arginine transport and arginine-derived nitric oxide production in a murine breast cancer cell line

Inflammatory mediators stimulate arginine-derived nitric oxide (NO) production in a variety of cells. The purpose of this study was to determine if the inflammatory mediators, endotoxin (LPS) and interferon gamma (IFN), stimulate arginine transport and nitric oxide production in a murine breast cancer cell line. We also investigated the effect of the nitric oxide synthase (NOS) inhibitors, omega-nitro-L-arginine methyl ester (LNAME) and aminoguanidine (AG), as well as the effect of varying the concentration of L-arginine in the cellular media, on arginine transport and NO production in these tumors cells. Confluent EMT-6 murine breast cancer cells were incubated with LPS (10 microgram/ml) and IFN (50 units/ml) in the presence or absence of the NOS inhibitors, L-NAME (2 mM) or AG (1 mM), and arginine transport (using L-[3H]arginine) and NO production (the stable end-product nitrite was assayed using the Greiss reagent) were measured at various time points. In addition, the effect of varying the concentration of L-arginine (0, 10, 100, 1000, 10,000 mM) in the cellular media on stimulated L-arginine transport and nitrite accumulation was assessed. Incubation of EMT-6 with LPS and IFN stimulated arginine transport approximately 70% over control levels at 12 hr and transport returned to basal levels at 24 hr. LPS/IFN-stimulated EMT-6 cells produced 25 microM nitrite at 24 hr and reached a plateau of 55 microM nitrite at 48 hr. The NO synthase inhibitors, L-NAME and AG, failed to inhibit basal and stimulated levels of arginine transport, but significantly inhibited nitrite accumulation, which was restored by 10 mM L-arginine. Finally, L-arginine was necessary in the media for nitrite accumulation by LPS/IFN-stimulated cells, with maximal accumulation at 1 mM L-arginine. In summary, LPS/IFN stimulate arginine transport and NO production in the EMT-6 breast cancer cell line. L-NAME and AG do not inhibit basal or stimulated arginine transport in this tumor cell line and extracellular L-arginine is required for NO synthesis in these cells. LPS/IFN stimulation of arginine transport may represent an adaptive response to provide increased substrate for enhanced tumor cell NO production.

Bulimia and interpersonal relationships: an extension of a longitudinal study

We examined changes in bulimia in female college students and changes in the relationship between bulimia and satisfaction with interpersonal relationships. We extended data collected from a 19-month time period in a previous study to a 31-month time period. Bulimics, subclinical bulimics, and normals showed a leveling off of the previous decline in bulimic symptoms assessed at the 19-month testing. There were strong negative correlations between the Bulimia Test and ratings of satisfaction with male interpersonal relationships, but the correlations were not significant for satisfaction with female relationships.

Body shape satisfaction in female exercisers and nonexercisers

Twenty-eight high frequency exercisers, twenty-six moderate frequency exercisers, and twenty nonexercisers were recruited to examine the relationship between exercise and body shape satisfaction in women. All subjects were within average body weight and body fat percentage, and those subjects who reported the clinical features of anorexia nervosa and/or bulimia nervosa were not included in the data analysis. Results showed that the high frequency exercisers had a significantly more negative view of their body shape than a group of moderate exercisers and nonexercisers. In addition, high frequency exercisers were more likely to continue to exercise even when feeling ill than were moderate exercisers. Group differences between moderate and high frequency exercisers were not found for exercising while injured. Differences in exercise attitudes and habits of the two groups are discussed in addition to their reasons for exercising.

Bulimia: prevalence and component factors in college women

Using a measure of bulimia (BULIT) that has demonstrated validity and reliability, the prevalence of bulimia among three samples of college females was found to range from 2.0 to 3.8%. These percentages are substantially lower than most previous reports would suggest. Factor analysis of the BULIT data revealed that the binging factor accounted for 63% of the variance. Other factors identified include vomiting, negative feelings about overeating, menstruation problems, preference for high caloric/easily ingested food, and weight fluctuations. The intercorrelations among the factors were examined and the implications of these data for the proposed revised DSM-III criteria for bulimia are discussed.