Membrane‐Surface Anchoring of Charged Diacylglycerol‐Lactones Correlates with Biological Activities

Synthetic diacylglycerol‐lactones (DAG‐lactones) are effective modulators of critical cellular signaling pathways, downstream of the lipophilic second messenger diacylglycerol, that activate a host of protein kinase C (PKC) isozymes and other nonkinase proteins that share similar C1 membrane‐targeting domains with PKC. A fundamental determinant of the biological activity of these amphiphilic molecules is the nature of their interactions with cellular membranes. This study examines the biological properties of charged DAG‐lactones exhibiting different alkyl groups attached to the heterocyclic nitrogen of an α‐pyridylalkylidene chain, and particularly the relationship between membrane interactions of the substituted DAG‐lactones and their respective biological activities. Our results suggest that bilayer interface localization of the N‐alkyl chain in the R² position of the DAG‐lactones inhibits translocation of PKC isoenzymes onto the cellular membrane. However, the orientation of a branched alkyl chain at the bilayer surface facilitates PKC binding and translocation. This investigation emphasizes that bilayer localization of the aromatic side residues of positively charged DAG‐lactone derivatives play a central role in determining biological activity, and that this factor contributes to the diversity of biological actions of these synthetic biomimetic ligands.     

Recruitment of minority group students and women.

Examined recruitment efforts of 65 fully approved American Psychological Association doctoral programs in clinical psychology. Results suggest that the programs were ambivalent about the recruitment of minority groups and of women in particular. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Warranty periods for production lots based on fatigue-test data

A two-parameter Weibull model for failure time is assumed. An easily implemented method is developed for calculating, from information obtained from a possibly censored life test, an approximate warranty period before which the $\text{k}$th failure occurs in a production lot of given size with some small specified probability. The precision of the approximation is investigated and a numerical example applied to failure data is given.The procedure developed can also be used for obtaining lower prediction limits for ultimate strengths of composite structures in production lots of specified size and for certain models other than the Weibull.     

A time-space tradeoff for sorting on non-oblivious machines

A model of computation is introduced which permits the analysis of both the time and space requirements of non-oblivious programs. Using this model, it is demonstrated that any algorithm for sorting n inputs which is based on comparisons of individual inputs requires time-space product proportional to n².     

Call for Papers: Special Issue on Aquatic Chemical Ecology

Call for Papers

Call for Papers: Special Issue on Aquatic Chemical Ecology