Membrane fluidity matters: Hyperthermia from the aspects of lipids and membranes

Hyperthermia is a promising treatment modality for cancer in combination both with radio- and chemotherapy. In spite of its great therapeutic potential, the underlying molecular mechanisms still remain to be clarified. Due to lipid imbalances and 'membrane defects' most of the tumour cells possess elevated membrane fluidity. However, further increasing membrane fluidity to sensitise to chemo-or radiotherapy could have some other effects. In fact, hyperfluidisation of cell membrane induced by membrane fluidiser initiates a stress response as the heat shock protein response, which may modulate positively or negatively apoptotic cell death. Overviewing some recent findings based on a technology allowing direct imaging of lipid rafts in live cells and lipidomics, novel aspects of the intimate relationship between the 'membrane stress' of tumour cells and the cellular heat shock response will be highlighted. Our findings lend support to both the importance of membrane remodelling and the release of lipid signals initiating stress protein response, which can operate in tandem to control the extent of the ultimate cellular thermosensitivity. Overall, we suggest that the fluidity variable of membranes should be used as an independent factor for predicting the efficacy of combinational cancer therapies

Phosphatidylserine-Induced Factor Xa Dimerization and Binding to Factor Va Are Competing Processes in Solution

A soluble, short chain phosphatidylserine, 1,2-dicaproyl-sn-glycero-3-phospho-L-serine (C6PS), binds to discrete sites on FXa, FVa, and prothrombin to alter their conformations, to promote FXa dimerization (K(d) ~ 14 nM), and to enhance both the catalytic activity of FXa and the cofactor activity of FVa. In the presence of calcium, C6PS binds to two sites on FXa, one in the epidermal growth factor like (EGF) domain and one in the catalytic domain; the latter interaction is sensitive to Na(+) binding and probably represents a protein recognition site. Here we ask whether dimerization of FXa and its binding to FVa in the presence of C6PS are competitive processes. We monitored FXa activity at 5, 20 and 50 nM FXa while titrating with FVa in the presence of 400 µM C6PS and 3 or 5 mM Ca(2+) to show that the apparent K(d) of FVa-FXa interaction increased with increasing FXa concentration at 5 mM Ca(2+), but the K(d) was only slightly affected at 3 mM Ca(2+). A mixture of 50 nM FXa and 50 nM FVa in the presence of 400 µM C6PS yielded both Xa homodimers and Xa ·Va heterodimers but no FXa dimers bound to FVa. A mutant FXa (R165A) that has reduced prothrombinase activity showed both reduced dimerization (K(d)~147 nM) and reduced FVa binding (apparent K(d), = 58, 92 and 128 nM, respectively for 5, 20 and 50 nM R165A FXa). Native gel electrophoresis showed that the GLA-EGF(NC) fragment of FXa (lacking the catalytic domain) neither dimerized nor formed a complex with FVa in the presence of 400 µM C6PS and 5 mM Ca(2+). Our results demonstrate that the dimerization site and FVa binding site are both located in the catalytic domain of FXa and that these sites are linked thermodynamically

Applying the techniques of neutralization to the study of cybercrime

Cybercrime scholars have used a wide range of criminological theories to understand crime and deviance within digital contexts. Among the most frequently cited theoretical frameworks used in this space has been the techniques of neutralization, first proposed by Gresham Sykes and David Matza. This body of work has demonstrated the myriad ways that individual cyber-delinquents have applied the techniques of neutralization as a justification for their deviance. A thorough review of this research reveals decidedly mixed support for neutralization theory. This chapter provides an in-depth review of these studies and seeks to account for this mixed result. This is done by chronicling the methodological underpinnings of this work, and in doing so highlights the challenges facing this literature with respect to the conceptualization and measurement of Sykes and Matza’s theory in the cyber realm. This is accomplished in two parts. First, we review the body of literature that analyzes the techniques of neutralization as a single combined construct (i.e., items are combined to produce a single measure of neutralization), and flag some of the advantages, but also pitfalls of this approach. Second, we review the treatment of individual techniques of neutralization as distinct constructs within the literature (i.e., a technique is measured and analyzed separate to others) and detail some of the common methodological hurdles encountered by researchers. The chapter concludes by elaborating on persistent gaps or challenges posed in making such assessments and proposes a path forward for future cybercrime research incorporating this framework.Russell Brewer, Sarah Fox, Caitlan Mille