Mario Marcel Salas Papers

Letter from Nolan A. Bowie to Mario Marcel Salas, president of the Black Coalition on Mass Media (BCMM). He writes to share his opinion on the dispute that developed between BCMM and KAPE radio, and as to whether or not the Federal Communications Commission (FCC) would consider his petition to deny the radio station a license renewal. He doesn't think it will go far, but encourages Mr. Salas to not give up

Direct Visualization of Membrane Leakage Induced by the Antibiotic Peptides: Maculatin, Citropin, and Aurein

Membrane lysis caused by antibiotic peptides is often rationalized by means of two different models: the so-called carpet model and the pore-forming model. We report here on the lytic activity of antibiotic peptides from Australian tree frogs, Maculatin 1.1, Citropin 1.1, and Aurein 1.2, on POPC or POPC/POPG model membranes. Leakage experiments using fluorescence spectroscopy indicated that the peptide/lipid mol ratio necessary to induce 50% of probe leakage was smaller for Maculatin compared with Aurein or Citropin, regardless of lipid membrane composition. To gain further insight into the lytic mechanism of these peptides we performed single vesicle experiments using confocal fluorescence microscopy. In these experiments, the time course of leakage for different molecular weight (water soluble) fluorescent markers incorporated inside of single giant unilamellar vesicles is observed after peptide exposure. We conclude that Maculatin and its related peptides demonstrate a pore-forming mechanism (differential leakage of small fluorescent probe compared with high molecular weight markers). Conversely, Citropin and Aurein provoke a total membrane destabilization with vesicle burst without sequential probe leakage, an effect that can be assigned to a carpeting mechanism of lytic action. Additionally, to study the relevance of the proline residue on the membrane-action properties of Maculatin, the same experimental approach was used for Maculatin-Ala and Maculatin-Gly (Pro-15 was replaced by Ala or Gly, respectively). Although a similar peptide/lipid mol ratio was necessary to induce 50% of leakage for POPC membranes, the lytic activity of Maculatin-Ala and Maculatin-Gly decreased in POPC/POPG (1:1 mol) membranes compared with that observed for the naturally occurring Maculatin sequence. As observed for Maculatin, the lytic action of Maculatin-Ala and Maculatin-Gly is in keeping with the formation of pore-like structures at the membrane independently of lipid composition

Adult pituitary stem cells

Underlying mechanisms leading to pituitary plasticity by which the gland adapts the number of hormone-producing cell to the continuously changing physiological requirements, are still poorly understood. Adult stem cells were shown to direct homeostatic cell maintenance, regeneration and functional plasticity in several organs and tissues. Only recently potential stem cells were identified and phenotypically characterized in adult pituitary. Multiple possible stem/progenitor cell candidates were proposed but different studies have been only partially reconciled. Here, we critically analyzed the reports addressing the identification of adult pituitary stem cells, trying, when possible, to reunite the results of the different studies. Nonetheless, in light of the still non-complete characterization of these cells, some discrepancies among the published studies are still apparent. Importantly, long-term in vitro self-renewal, a defining features of stem cells, remains to be unequivocally demonstrated. Finally, the potential role of adult pituitary stem (or progenitor) cells in pituitary adenoma development will be discussed

Negotiating the Contested Terrain of Drug Testing in the Australian Workplace

Alcohol and illicit substance abuse in the workplace is an important human resource and industrial relations issue. Although more sophisticated measures have been developed to test and monitor drug use in the workplace, and despite tacit union support on occupational health and safety grounds, the implementation of drug testing procedures remains contentious. This paper examines the arguments for and against drug testing in the workplace using an Australian case study where drug testing resulted in industrial disputation that led to legal intervention and remedy

Representation of Vulnerability and the Elderly : A Total Survey Error Perspective on the VLV Survey

This chapter focuses on the "Vivre-Leben-Vivere" (VLV) research and explains how the team in charge has dealt with the issue of representing old people in Switzerland and the vulnerable persons within this population. For this purpose, we draw inspiration from the "total survey error" perspective and discuss the procedures that were used to collect the information, but also the quality of the information itself. We present some of VLV's methodological choices, such as the contact procedures that were designed to "capture" the most vulnerable individuals, especially in a context where refusal rates for participation in surveys are increasing. We also consider the missing values in responses to some "complex" topics. Results show that participation rates are highly related to the effort that was made in order to recruit the individuals. This is critical for the VLV project, where people can show different degrees of vulnerability related to age, health, and/or poverty. In this sense, efforts such as repeated calls, home visits, and the proxy procedure were successful both in a general perspective and more specifically for a fair inclusion of vulnerable persons in the survey. At the same time, the non-response rates show to what extent it is difficult to explain the personal decision not to respond to a survey or to a question. We can find some traces of "interviewer effects" in the analysis of item non-responses, which we have done by using a logistic regression for one of the psychological tests included in VLV. Some aspects relate to interviewer and respondent characteristics, but others relate to the interview context, all highlighting the complex social interactions at stake