Anuran skin is known to be a rich source of antimicrobial peptides although their therapeutic potential is often limited due to their toxicity against mammalian cells. The analysis of structure-activity relationships among anuran antimicrobial peptides provided the parameters to construct the "Mutator" tool for improving their selectivity for bacterial cells, by suggesting appropriate point substitutions. Double substitution analogues [K2, K16] of the Xenopus tropicalis peptide XT-7 and [I2, K19] of the Ascaphus truei peptide ascaphin-8 were predicted by this tool to have an increased 'therapeutic index' (TI = HC(50)/MIC for erythrocytes with respect to bacteria) > 80. The mutated peptides were synthesized and respectively found to have experimental TI values > 130 for S. aureus or E. coli, a considerable improvement with respect to TI < 37 for the parent compounds. Circular dichroism studies of the mutated peptides suggested this may in part be due to variations in the α-helical structure. For P. aeruginosa, which is more resistant to XT-7, the TI increased in the mutated peptide from 5 to >270, also due to a significant improvement in minimal inhibitory concentration. We have shown that the Mutator tool is capable of suggesting limited variations in natural anuran peptides capable of increasing peptide selectivity, by decreasing toxicity against mammalian erythrocytes, in general without compromising antibacterial activity. The tool is freely available on the Mutator Web server at http://split4.pmfst.hr/mutator/.

Abstract 181 Studies conducted over the past decade have revealed a strong association between the mutational status of the immunoglobulin heavy-chain variable region (IGHV) genes and clinical course in patients with chronic lymphocytic leukemia (CLL). In patients with aggressive CLL, the leukemic cells typically express B cell receptors (BCRs) encoded by unmutated IGHV genes, whereas these genes are most often mutated in leukemic cells from patients with indolent disease. The mutational status of the IGHV genes reflects features of the antigen, such as antigen structure, form, presentation and affinity, indicating that the difference in the clinical course between IGHV-unmutated and IGHV-mutated CLL could be due to recognition of different types of antigens. In line with this possibility, recent studies have shown that IGHV-unmutated CLL (U-CLL) cells frequently express polyreactive BCRs that bind with low affinity to both microbial antigens and autoantigens translocated or exposed on apoptotic cells, whereas such reactivity is infrequent in IGHV-mutated CLL (M-CLL). To further explore the possibility that the clinical course in CLL is determined by the availability of particular types of antigenic stimuli, we investigated the impact of different antigen/BCR interactions on leukemia development and behavior in the Eμ-TCL1 transgenic mouse model of CLL. We initially established three cohorts of Eμ-TCL1 transgenic mice that expressed transgenic BCRs with different antigen specificity. Two of these cohorts expressed low-affinity unmutated transgenic BCRs reactive with the antigens phosphatidylcholine (PtC) and Sm (IgPtC and IgSm, respectively), whereas the third cohort expressed a high-affinity mutated transgenic BCR (IgHEL) specific for the antigen hen egg lysozyme (HEL). Of note, Sm is a ribonucleoprotein complex that is translocated to the surface of apoptotic cells and has been shown to be recognized by certain human U-CLL BCRs, whereas PtC is a cell membrane component that is exposed on senescent red blood cells and gut bacteria. Because no data are currently available regarding the reactivity of the M-CLL BCRs, we subdivided the cohort of Eμ-TCL1/IgHEL double transgenic mice into four additional cohorts. These included a cohort without antigen (Eμ-TCL1/IgHEL), a cohort in which HEL was provided as a foreign antigen (Eμ-TCL1/IgHEL double transgenic mice repetitively immunized with particles coated with HEL and CpG oligonucleotides), a cohort in which HEL was provided as a soluble autoantigen (Eμ-TCL1/IgHEL/sHEL triple transgenic mice) and a cohort in which HEL was provided as a membrane-bound autoantigen exposed on apoptotic cells (Eμ-TCL1/IgHEL/mHEL-KK triple transgenic mice). Each cohort consisted of 12–14 animals, of which at least 8 have been followed for >1 year. Animals from all cohorts developed CD5-positive B cell leukemias, but only in Eμ-TCL1/IgSm and Eμ-TCL1/IgPtC mice the leukemic cells expressed a transgenic BCR. In Eμ-TCL1/IgHEL mice the leukemias were always derived from the small percentage of B cells that express an endogenous BCR, whereas B cells that express the transgenic IgHEL BCR were never transformed. Interestingly, leukemia development and progression was more rapid in Eμ-TCL1/IgPtC than Eμ-TCL1/IgSm transgenic mice (7/14 at 6 months of age and 2/10 at 8 months of age, respectively). Since PtC is expressed as both a foreign- (gut flora) and self- (senescent red blood cells) antigen, we investigated whether suppression of gut flora will affect the growth of adoptively transferred Eμ-TCL1/IgPtC leukemias. Pretreatment of syngeneic recipient mice with a three-week course of broad-spectrum antibiotics significantly delayed leukemia growth, suggesting that PtC is more potent in driving the expansion of the leukemic clone when expressed as a foreign than self antigen. To summarize, these data demonstrate that U-CLL can be induced by both microbial antigens and autoantigens exposed on apoptotic cells, including autoantigens that are recognized by human CLL cells, such as Sm. In contrast, M-CLL can not be induced by chronic or repetitive antigen stimulation, regardless whether the antigen is provided as a foreign antigen, as a soluble autoantigen, or as a membrane-bound autoantigen exposed on apoptotic cells. Collectively, these data suggest that the mechanisms that drive U-CLL and M-CLL are different and indicate that only U-CLL is an antigen-driven disease. Disclosures: No relevant conflicts of interest to declare.

BackgroundWe evaluated the association between linear standard Heart Rate Variability (HRV) measures and vascular, renal and cardiac target organ damage (TOD).MethodsA retrospective analysis was performed including 200 patients registered in the Regione Campania network (aged 62.4 ± 12, male 64%). HRV analysis was performed by 24-h holter ECG. Renal damage was assessed by estimated glomerular filtration rate (eGFR), vascular damage by carotid intima-media thickness (IMT), and cardiac damage by left ventricular mass index.ResultsSignificantly lower values of the ratio of low to high frequency power (LF/HF) were found in the patients with moderate or severe eGFR (p-value < 0.001). Similarly, depressed values of indexes of the overall autonomic modulation on heart were found in patients with plaque compared to those with a normal IMT (p-value <0.05). These associations remained significant after adjustment for other factors known to contribute to the development of target organ damage, such as age. Moreover, depressed LF/HF was found also in patients with left ventricular hypertrophy but this association was not significant after adjustment for other factors.ConclusionsDepressed HRV appeared to be associated with vascular and renal TOD, suggesting the involvement of autonomic imbalance in the TOD. However, as the mechanisms by which abnormal autonomic balance may lead to TOD, and, particularly, to renal organ damage are not clearly known, further prospective studies with longitudinal design are needed to determine the association between HRV and the development of TOD.

This paper presents the results of an experimental study in which users teleoperating a mobile robot evaluated three controllers: a keyboard, a game controller, and a touchpad interface. It is motivated by the need to engage a broader, non-expert user audience in teleoperation as robots become more prevalent in everyday applications. Analysis focuses on how specific control elements and the user's comfort with a device improve the operator's sense of immersion in the task and how this alters performance. Our results show that perceived controllability of the controller, users' level of technological anxiety, and the physical nature of feedback from the controller had an effect on user feelings of immersion and presence. Our findings have implications for the development of controllers that can be used for teleoperating robots by a broad user audience.

This paper contributes to the study of interaction between groups of people and groups of robots by examining the effect of group size on people's attitudes and behaviors toward robots as interaction partners. Our work is motivated by psychological research on human intergroup dynamics, particularly the interindividual-intergroup discontinuity effect, which suggest that interactions among groups are more competitive than interactions among individuals. To test the discontinuity effect in the context of human-robot interaction, we conducted a between-subjects experiment with four conditions, derived by differentiating the ratio of humans to robots in the interaction (one or two humans interacting with one or two robots). Participants played a game with robots in which they were given a chance to exhibit competitive and cooperative behaviors, which we tracked. We also measured changes in participants' attitudes toward robots following gameplay. Our results show that people playing in groups behave more competitively towards the robots than individual human players. However, participants' attitudes toward robots did not change after the short-term interaction.