Social and attitudinal determinants of viral marketing dynamics

At this time of uncertainty, viral marketing is emerging as one of the most intriguing communication strategies, due to low cost and the results it obtains. However, the success of this kind of practice depends on a range of factors including what we explore and refer to in the present research as the individual’s “viral dynamics”. We thus propose a causal model in which viral dynamics is determined by the individual’s social capital and prior attitudes. Based on a survey of young adults, the authors test the effects of structural and relational capital as well as attitudes on viral dynamics. The results evidence that the individual’s connectedness in the email network does not impact viral dynamics, whereas the individual’s integration and relationship with the network and the attitudes towards viral messages prove critical to the individual involved in the receiving-forwarding process.     

Viscoelastic properties of poly(vinyl alcohol) hydrogels and ferrogels obtained through freezing-thawing cycles

We report the preparation of poly(vinyl alcohol) (PVA) hydrogels obtained through freezing-thawing cycles. The viscoelastic properties of these gels using parallel-plate shear mode were evaluated as a function of temperature, time, degree of swelling, concentration and the number of freezing-thawing cycles. The storage modulus was analyzed on the basis of a theoretical model based on the scaling approach. These results provide additional evidence for a non-crystalline nature of the structure of PVA cryogels.Furthermore, PVA ferrogels have been prepared from PVA aqueous solutions and a ferrofluid through freezing-thawing cycles. The viscoelastic properties of these materials have been evaluated. It is shown that the variation of the storage modulus with ferrofluid concentration cannot be fitted using classical theories what has been attributed to the small dimensions of the particles in the ferrogels and to the magnetic interactions between particles.     

Altered Cortical Palmitoylation Induces Widespread Molecular Disturbances in Parkinson’s Disease

The relationship between Parkinson’s disease (PD), the second-most common neurodegenerative disease after Alzheimer’s disease, and palmitoylation, a post-translational lipid modification, is not well understood. In this study, to better understand the role of protein palmitoylation in PD and the pathways altered in this disease, we analyzed the differential palmitoyl proteome (palmitome) in the cerebral cortex of PD patients compared to controls (n = 4 per group). Data-mining of the cortical palmitome from PD patients and controls allowed us to: (i) detect a set of 150 proteins with altered palmitoylation in PD subjects in comparison with controls; (ii) describe the biological pathways and targets predicted to be altered by these palmitoylation changes; and (iii) depict the overlap between the differential palmitome identified in our study with protein interactomes of the PD-linked proteins α-synuclein, LRRK2, DJ-1, PINK1, GBA and UCHL1. In summary, we partially characterized the altered palmitome in the cortex of PD patients, which is predicted to impact cytoskeleton, mitochondrial and fibrinogen functions, as well as cell survival. Our study suggests that protein palmitoylation could have a role in the pathophysiology of PD, and that comprehensive palmitoyl-proteomics offers a powerful approach for elucidating novel cellular pathways modulated in this neurodegenerative disease.     

A stereoselective cobalt-containing nitrile hydratase

Nitrile hydratase from Pseudomonas putida NRRL-18668 has been purified and characterized. The purified enzyme catalyzes the hydration of 2(S)-(4'-chlorophenyl)-3-methylbutyronitrile at least fifty times faster than that of 2(R)-(4'-chlorophenyl)-3-methylbutyronitrile. This enzyme is a member of the class of nitrile hydratase that contains cobalt. Visible absorption and CD spectra suggest the cobalt exists as a non-corrin low-spin Co3+ ion in a tetragonally-distorted octahedral ligand field. Chemical reduction of the native enzyme results in a species with the EPR signature of a low-spin Co2+ complex. Like the other cobalt-containing nitrile hydratases, this enzyme is relatively stable, maintaining its activity below 35 degrees C, and it shows a broad activity optimum between pH 7.2 and 7.8. The structural genes for this enzyme have been cloned and sequenced. The deduced amino acid sequences for the alpha and beta subunits show 48-63% and 35-41% homology, respectively, to other sequenced nitrile hydratases. In particular, the cysteine residues in the alpha subunit that have been suggested to coordinate the metal ion in the iron-containing nitrile hydratases [Brennan, B. A., Cummings, J. G., Chase, D. B., Turner, I. M., Jr., & Nelson, M. J. (1996) Biochemistry 35, 10068-10077] are conserved in this enzyme, suggesting that this nitrile hydratase, like the enzyme from Rhodococcus rhodochrous J1, is a member of a newly described class of metalloenzymes with Co3+-thiolate ligation [Brennan, B. A., Alms, G., Nelson, M. J., Durney, L. T., & Scarrow, R. C. (1996) J. Am. Chem. Soc. 118, 9194-9195].     

Creative Leaders: A Decade of Contributions from Creativity and Innovation Management Journal

Articles published in Creativity and Innovation Management volumes 1–9 (1991–2000) have been examined for their contributions to understanding of leadership as a process contributing to creativity and innovation. The study reveals nine overlapping themes, within each of which leadership plays a part in the production of creative insights or innovative productivity. However, for many authors, leadership remains an implicit factor within their models of change. We suggest that leadership, creativity and innovation are knowledge systems which can be more closely integrated for improved theory and practice within communities of practice.     

Thin frozen-dried cryosections and biological X-ray microanalysis

The application of X-ray microanalysis to problems of cell physiology required the development of methods to retain diffusible substances within the subcellular compartments that they occupied in vivo. Several groups have developed methods of rapidly freezing small samples in ways that minimize mechanical traumae and ice crystal formation. This provides a narrow zone from which cryosections, believed to be representative of the in vivo distribution of electrolytes, can be cut. The production of thin (less than 0·5 μm) cryosections that are apparently free of diffusion can be routinely performed when temperature parameters are kept below 173 K. Efficient cryosectioning requires several modifications to commercially available machines, in order to improve the ease and reliability with which various manipulations can be carried out. Initial attempts to localize calcium at the subcellular level were disturbed by the use of mechanically damaged specimens and by insufficiently cold conditions in the cryochamber. Such sections indicated that mitochondria were calcium-rich organelles. When tissue freezing and cryosectioning were performed under optimized conditions, mitochondrial calcium was so low as to be quantifiable only with difficulty. Available microanalytical results show that ER-rich cytoplasm and terminal cisternae of the sarcoplasmic reticulum seem to contain higher levels of calcium than mitochondria. Nuclei and secretory granules also contain more calcium than mitochondria.