Design and analysis of accelerated degradation tests for the stability of biological standards III. Principles of design

The principles of designing an accelerated degradation test for a biological standard are considered, with special emphasis on ensuring accuracy and precision of the predicted low temperature degradation rate. A three-stage design is proposed which initially monitors samples at the highest of the elevated temperatures, but which switches attention progressively to the lower temperatures as degradation begins to be detected. The advantages of this design over one where testing is carried out after a predetermined period are that it is (i) more efficient, (ii) more reliable and (iii) better suited to test the assumptions which underly the analysis of the results. Consideration is also given to additional checks which can be made on the stability of biological standards and to methods of monitoring long-term stability after the standard has been set up.     

Nothobranchius cooperi (Teleostei: Cyprinodontiformes): a new species of annual killifish from the Luapula River drainage,northern Zambia

Nothobranchius cooperi, Nagy, Watters and Bellstedt, new species, is described from seasonal streams and ephemeral pools associated with the upper Mansa River system in the middle Luapula drainage and systems draining into the low-lying area marginal to the southwestern part of Lake Bangweulu, in the Luapula province of northern Zambia. It belongs to the N. brieni species group. Males of Nothobranchius cooperi are distinguished from congeners by the following unique combination of characters: body scales with broad orange posterior margin, forming a highly irregular cross-barred pattern; anal fin fairly uniform orange-red with irregular to regular, light blue-green zone close to the base; caudal peduncle length 1.2–1.3 times its depth; prepelvic length 48.8–51.9% SL; and head depth 75–77% of head length. Genetic divergence of the mitochondrial COI and ND2 genes and nuclear S7 gene support the distinction of the new species from its closest known relative, N. rosenstocki and confirms its position in the N. brieni species group.     

Estrogen receptor concentration and social factors as predictors of natural killer cell activity in early-stage breast cancer patients. Confirmation of a model

Previous work of ours has demonstrated that a significant amount of natural killer (NK) activity variance after surgery in stage I and II breast cancer patients could be accounted for by both the estrogen receptor (ER) status of the tumor and by social factors, namely, perceived social support and seeking social support as a general coping strategy. As considerable evidence has accumulated that social support in both animal and human populations may have survival value, we sought to test the reliability of this regression model, using coping and perceived support factor values obtained at 3 months after surgery to account for concurrent follow-up NK activity in this serially assessed group of patients. It was found that the most significant variable predicting NK activity at follow-up was tumor ER concentration, with higher NK activity associated with ER- status. In addition, seeking social support as a coping strategy, as well as the perceived quality of support, also entered the model to account for a significant amount of NK activity variance (multivariate F = 5.25, p less than 0.001). If, as the literature suggests, NK activity is relevant to breast cancer control, and since ER- tumors have a worse prognosis, we suggest here that perhaps such tumors are resistant to control by NK cells because they lack the ability to attract an accumulation of effector cells to the tumor site, or because blocking factors at the site of the tumor prevent local tumor control at the site of action. The finding related to social support also replicates results from an independent sample of breast cancer patients. This finding, taken together with other evidence that this social variable is associated with longer survival in breast cancer populations, underscores the potential importance of this social support variable. Our findings also suggest one possible immunological variable involved, with potential clinical significance, for this patient population.