Territory quality and territorial behavior in two sympatric species of hummingbirds

Changes in territorial behavior of blackchinned hummingbirds ( Archilochus alexandri ) in response to experimental changes in territory quality were investigated using artificial feeders and simultaneous, pair-wise observations of owners. Some of the responses of A. alexandri were similar to those documented by a previous study of the Anna's hummingbird ( Calypte anna): A. alexandri defending rich territories spent more time on their territories, encountered a greater percentage of intruders, and chased more intruders than did A. alexandri defending poor territories. In contrast to C. anna, A. alexandri supplemented chases with energetically inexpensive threat vocalizations more extensively when territory quality was increased. This difference may be related to A. alexandri's more tenuous control of rich territories. When both species were observed on very poor territories, A. alexandri chased a greater percentage of intruders, consumed a greater proportion of available food, and obtained a greater net energy gain from their territories. When observed simultaneously on territories with ad lib food, both species defended highly exclusive territories but A. alexandri suffered higher intrusion pressure and spent more time and energy in defense. These interspecific differences in territorial behavior may facilitate sympatric coexistence of the two species through aggressive partitioning of flower patches according to productivity: the greater payoff received by C. anna on rich territories and A. alexandri on poor territories should favor a corresponding monopolization of rich areas by C. anna and poor areas by A. alexandri .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46878/1/265_2004_Article_BF00292181.pd

Coping with palliative chemotherapy.

Comparatively little is known about how patients with advanced cancer cope with palliative chemotherapy This study uses grounded theory to analyse the coping responses of 24 women with advanced breast or ovarian cancer Half the sample received chemotherapy at home, and the remainder were treated in hospital The results suggest that four predominant coping styles are used, think positive/fighter (n = 8), acceptance (n = 8), fearfulness (n = 5) and hopelessness (n = 3) In addition, a range of coping strategies that reduced the threat of chemotherapy are identified. The findings have implications for the provision of quality patient care in palliative therapy, especially in relation to individualizing patient educatio

Estrogen Metabolism and Risk of Breast Cancer in Postmenopausal Women

BACKGROUND: Estrogens are recognized causal factors in breast cancer. Interindividual variation in estrogen metabolism may also influence the risk of breast cancer and could provide clues to mechanisms of breast carcinogenesis. Long-standing hypotheses about how estrogen metabolism might influence breast cancer have not been adequately evaluated in epidemiological studies because of the lack of accurate, reproducible, and high-throughput assays for estrogen metabolites. METHODS: We conducted a prospective case–control study nested within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). Participants included 277 women who developed invasive breast cancer (case subjects) and 423 matched control subjects; at PLCO baseline, all subjects were aged 55–74 years, postmenopausal and not using hormone therapy, and provided a blood sample. Liquid chromatography–tandem mass spectrometry was used to measure serum concentrations of 15 estrogens and estrogen metabolites, in unconjugated and conjugated forms, including the parent estrogens, estrone and estradiol, and estrogen metabolites in pathways defined by irreversible hydroxylation at the C-2, C-4, or C-16 positions of the steroid ring. We calculated hazard ratios (HRs) approximating risk in highest vs lowest deciles of individual estrogens and estrogen metabolites, estrogens and estrogen metabolites grouped by metabolic pathways, and metabolic pathway ratios using multivariable Cox proportional hazards models. All statistical tests were two-sided. RESULTS: Nearly all estrogens, estrogen metabolites, and metabolic pathway groups were associated with an increased risk of breast cancer; the serum concentration of unconjugated estradiol was strongly associated with the risk of breast cancer (HR = 2.07, 95% confidence interval [CI] = 1.19 to 3.62). No estrogen, estrogen metabolite, or metabolic pathway group remained statistically significantly associated with the risk of breast cancer after adjusting for unconjugated estradiol. The ratio of the 2-hydroxylation pathway to parent estrogens (HR = 0.66, 95% CI = 0.51 to 0.87) and the ratio of 4-hydroxylation pathway catechols to 4-hydroxylation pathway methylated catechols (HR = 1.34, 95% CI = 1.04 to 1.72) were statistically significantly associated with the risk of breast cancer and remained so after adjustment for unconjugated estradiol. CONCLUSIONS: More extensive 2-hydroxylation of parent estrogens is associated with lower risk, and less extensive methylation of potentially genotoxic 4-hydroxylation pathway catechols is associated with higher risk of postmenopausal breast cancer