Measuring Emotional Contagion in Social Media

Social media are used as main discussion channels by millions of individuals every day. The content individuals produce in daily social-media-based micro-communications, and the emotions therein expressed, may impact the emotional states of others. A recent experiment performed on Facebook hypothesized that emotions spread online, even in absence of non-verbal cues typical of in-person interactions, and that individuals are more likely to adopt positive or negative emotions if these are over-expressed in their social network. Experiments of this type, however, raise ethical concerns, as they require massive-scale content manipulation with unknown consequences for the individuals therein involved. Here, we study the dynamics of emotional contagion using a random sample of Twitter users, whose activity (and the stimuli they were exposed to) was observed during a week of September 2014. Rather than manipulating content, we devise a null model that discounts some confounding factors (including the effect of emotional contagion). We measure the emotional valence of content the users are exposed to before posting their own tweets. We determine that on average a negative post follows an over-exposure to 4.34% more negative content than baseline, while positive posts occur after an average over-exposure to 4.50% more positive contents. We highlight the presence of a linear relationship between the average emotional valence of the stimuli users are exposed to, and that of the responses they produce. We also identify two different classes of individuals: highly and scarcely susceptible to emotional contagion. Highly susceptible users are significantly less inclined to adopt negative emotions than the scarcely susceptible ones, but equally likely to adopt positive emotions. In general, the likelihood of adopting positive emotions is much greater than that of negative emotions.     

Element concentration variability in the whaleworm Anisakis simplex s.l.

Concentrations of the elements C, N, Fe, Na, K, Ca and Mg were analysed by chromatography and atomic absorption spectrometry in the whaleworm Anisakis simplex sensu lato. Nearly all mean inorganic element concentrations measured were higher in adult worms than in larval forms. Similarly, adults contained significantly higher nitrogen (i.e. lower C/N ratio values) than either eggs or larvae. Evidence for the significance of the parasitic life cycle stage and the systematic position of their hosts on the element concentration variability is discussed.     

Solubilization of immune precipitates by complement in the absence of properdin or factor D

Various experiments have demonstrated that immune precipitates (IPs) are not solubilized by complement in the absence of alternative pathway function. To determine whether the characteristics of the IPs were responsible for these observations, we studied the solubilization (Sol) of IPs formed by bovine serum albumin (BSA)-rabbit antiBSA and tetanus toxoid (TT)-human antiTT. Sera deficient in properdin solubilized a fraction of BSA-antiBSA precipitates, although only when the IPs were formed in antibody excess. The same sera solubilized TT-antiTT precipitates with some delay but almost as efficiently as normal serum. Factor D-depleted serum solubilized a fraction of TT-antiTT precipitates too, indicating that Sol may proceed through activation of the classical pathway only. Thus, the requirements for complement-mediated Sol depend on the characteristics of the IPs and do not necessarily include alternative pathway function.     

Composition of citrus pulp

Eight groups of citrus varieties grown in Spain were included in this study. Citrus pulp composition was (dry matter basis) 60–65% peel, 30–35% segment pulp and 0–10% seeds. Citrus seeds had a high percentage of protein, ether extract and crude fibre. Segment pulp contained slightly less fibre than citrus pulp. The proximate composition of citrus pulp was similar to that of the peel fraction and did not differ from previous results. Significant differences in fibre and acid detergent lignin of the dried citrus pulp samples were found between varieties.The drying process was studied. Temperatures over 130°C and the addition of calcium hydroxide affected some fractions of the pulp, mainly by increasing ash and fibre contents.     

Rat pheochromocytoma tyrosine hydroxylase is phosphorylated on serine 40 by an associated protein kinase

Tyrosine hydroxylase, a key enzyme in the biosynthesis of catecholamines, was previously shown to be phosphorylated on four distinct serine residues in PC12 cell cultures, each one being specific for the kinase system involved (McTigue, M., Cremins, J., and Halegoua, S. (1985) J. Biol. Chem. 260, 9047-9056). A cAMP- and Ca2+-independent protein kinase was found to be associated with tyrosine hydroxylase purified from rat pheochromocytoma tumor. The use of this activity and the availability of a large amount of purified tyrosine hydroxylase allowed identification of the site phosphorylated by this kinase activity. A peptide of 1.5 kDa (about 12 residues long), carrying the phosphorylation site, was released from 32P-labeled tyrosine hydroxylase by limited proteolysis with trypsin. This peptide was isolated from trypsinized tyrosine hydroxylase by sequential gel filtration and ion exchange chromatographies. Analysis by thin layer chromatography of an acid hydrolysate of the peptide revealed that it contained phosphoserine. The sequence determination of the peptide showed that it corresponded to the residues 38-45 in the tyrosine hydroxylase primary structure (Arg-Gln-Ser(P)-Leu-Ile-Glu-Asp-Ala). Thus, the associated kinase phosphorylated Ser-40, one of the phosphorylation sites for the cAMP-dependent protein kinase also found in rat pheochromocytoma tumors. These results are compared to those recently appearing in a report by Campbell et al. (Campbell, D. G., Hardie, D. G., and Vulliet, P. R. (1986) J. Biol. Chem. 261, 10489-10492).     

Alloreactive lymphocytes from T cell receptor (beta-chain) transgenic mice do not mediate a graft-versus-host reaction.

The injection of mature T cells into a tolerant or immunocompromised allogeneic host animal produces a graft versus host response (GVHR) that can result in splenomegaly, immunosuppression and death of the host animal. We demonstrate here that lymphocytes from T cell receptor beta-chain (TCR-beta) transgenic mice, in which the expression of the transgene inhibits endogenous beta- and gamma-gene rearrangements and thus causes abnormal T cell development, are unable to mediate a GVHR. The GVHR was measured after the injection of lymphocytes from transgenic mice into normal F1 mice and also after transplantation of bone marrow and lymphocytes from transgenic mice into lethally irradiated F1 recipients. In both systems, cells from transgenic mice failed to produce a significant GVHR. Cells from the transgenic mice were able to recognize the foreign histocompatibility Ag of the host in vitro and in vivo although the transgenic mice rejected skin grafts more slowly than controls. Thus, lymphocytes from transgenic mice were unable to produce a GVHR despite the presence of alloreactive T cells. These results suggest that lymphocytes from TCR-beta transgenic mice fail to mediate a GVHR either because lymphocytes with a single transgenic TCR-beta chain have a limited ability to recognize allogeneic cells in vivo or because the transgenic mice lack lymphocyte subsets that are important for the mediation of a GVHR.     

Associated Liver Partition and Portal Vein Ligation (ALPPS) vs Selective Portal Vein Ligation (PVL) for Staged Hepatectomy in a Rat Model. Similar Regenerative Response?

Associated liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a two-stage hepatectomy technique which can be associated with a hypertrophic stimulus on the future liver remnant (FLR) stronger than other techniques–such as portal vein ligation (PVL). However, the reason of such hypertrophy is still unclear, but it is suggested that liver transection combined with portal vein ligation (ALPPS) during the first stage of this technique may play a key role. The aim of this study is to compare the hypertrophic stimulus on the FLR and the clinical changes associated with both ALPPS and PVL in a rat surgical model. For this purpose, three groups of SD rats were used, namely ALPPS (n = 30), PVL (n = 30) and sham-treated (n = 30). The second stage of ALPPS (hepatectomy of the atrophic lobes), was performed at day 8. Blood and FLR samples were collected at 1, 24, 48 hours, 8 days and 12 weeks after the surgeries. ALPPS provoked a greater degree of hypertrophy of the FLR than the PVL at 48 hours and 8 days (p<0.05). The molecular pattern was also different, with the highest expression of IL-1β at 24h, IL-6 at 8 days, and HGF and TNF-α at 48 hours and 8 days (p<0.05). ALPPS also brought about a mild proliferative stimulus at 12 weeks, with a higher expression of HGF and TGF-β (p<0.05) than PVL. Clinically, ALPPS caused a significant liver damage during the first 48 hours, with a recovery of liver function at day 8. In conclusion, ALPPS seems to induce higher functional hypertrophy on the FLR than PVL at day 8. Such regenerative response seems to be leaded by a complex interaction between pro-mitogenic (IL-6, HGF, TNF-α) and antiproliferative (IL1-β and TGF-β) cytokines.     

Evolution of the spectrin repeat

We now know that the evolution of multidomain proteins has frequently involved genetic duplication events. These, however, are sometimes difficult to trace because of low sequence similarity between duplicated segments. Spectrin, the major component of the membrane skeleton that provides elasticity to the cell, contains tandemly repeated sequences of 106 amino acid residues. The same repeats are also present in α-actinin, dystrophin and utrophin. Sequence alignments and phylogenetic trees of these domains allow us to interpret the evolutionary relationship between these proteins, concluding that spectrin evolved from α-actinin by an elongation process that included two duplications of a block of seven repeats. This analysis shows how a modular protein unit can be used in the evolution of large cytoskeletal structures.