Spatial structure of hierarchical groups: testing for processes of aggregation,clustering, and spatial centrality in crayfish (Orconectes rusticus)

Competing group members tend to arrange in a social order that governs who will likely submit to whom. In many species the spatial distribution of individuals often reflects social status: dominants tend to occupy central locations while subordinates are often found along the group's periphery. This article explores the emergence of spatial consequences as a result of social rank differentiation. Rather than orienting centripetally, the movements of crayfish (Orconectes rusticus) primarily indicated a tendency to remain close to arena walls. Spatial locations were affected by the location of group members; but, rather than actively aggregating or clustering, individuals maintained a minimum distance. Previously established social rank did not affect spatial distributions. High population densities in the field are likely attributed to habitat constraints, rather than any social or centripetal tendencies of individual crayfish.     

Atherosclerotic lesions of supra-aortic arteries in diabetic patients

The aim of this prospective study was to determine the prevalence and localization of stenotic atherosclerotic lesions of supra-aortic arteries in diabetic patients according to age and sex. Angiograms obtained by digital subtraction angiography were analyzed in 150 diabetic patients (study group) and 150 non-diabetic patients (control group) with symptoms of cerebral ischemia. Diabetic patients were found to have a significantly higher prevalence of stenotic atherosclerotic lesions of the internal carotid artery. Lesions of the large supra-aortic arteries were significantly more common in the left than in the right side of the neck (p < 0.001), but the difference between the diabetic and the non-diabetic group did not reach statistical significance. Hemodynamic conditions were found to be more important than diabetes for the occurrence of atherosclerotic lesions in these arteries. Changes in the proximal segment of the left common carotid artery were the most common finding in diabetic patients, hence attention should be paid to this localization on control examinations.     

Effects of fighting decisions on formation and structure of dominance hierarchies

The characteristics of complex social systems often cannot be predicted from exploring individual agonistic interactions in isolation. In a series of models, this study linked the decision-making processes that govern dyadic interactions with the emergent properties of hierarchical structures in social groups. Contrary to the intuitive expectation that resolution of ambiguities in fighting between closely matched opponents effectively promotes the formation of a social hierarchy, engagement in contests with opponents of dissimilar status lead to a faster emergence of hierarchical structures. The increased certainty of outcome in such asymmetric contests both reinforced the previously established dominance, and allowed for an indirect resolution of existing ambiguous relationships. High-return fights also resulted in a more rapid hierarchy formation, while escalating in fights decreased the costs of maintaining hierarchical relationships and increased their stability.     

Helicobacter pylori disrupts NADPH oxidase targeting in human neutrophils to induce extracellular superoxide release

Helicobacter pylori (Hp) infection triggers a chronic influx of polymorphonuclear leukocyte neutrophils (PMNs) into the gastric mucosa. Although Hp reside in a neutrophil-rich environment, how these organisms evade phagocytic killing is largely unexplored. We now show that live Hp (strains 11637, 60190, DT61A, and 11916) are readily ingested by PMNs and induce a rapid and strong respiratory burst that is comparable to PMA. Relative to other particulate stimuli, Hp are more potent activators of PMNs than opsonized zymosan, Staphylococcus aureus, or Salmonella. Strikingly, biochemical and microscopic analyses demonstrate that Hp disrupt NADPH oxidase targeting such that superoxide anions are released into the extracellular milieu and do not accumulate inside Hp phagosomes. Specifically, nascent Hp phagosomes acquire flavocytochrome b558 but do not efficiently recruit or retain p47phox or p67phox. Superoxide release peaks at 16 min coincident with the appearance of assembled oxidase complexes in patches at the cell surface. Oxidant release is regulated by formalin-resistant and heat-sensitive bacterial surface factors distinct from urease and Hp(2-20). Following opsonization with fresh serum, Hp triggers a modest respiratory burst that is confined to the phagosome, and ingested bacteria are eliminated. We conclude that disruption of NADPH oxidase targeting allows unopsonized Hp to escape phagocytic killing, and our findings support the hypothesis that bacteria and PMNs act in concert to damage the gastric mucosa.     

The unsaturated acyclic nucleoside analogues bearing a sterically constrained (Z)-4′-benzamido-2′-butenyl moiety: Synthesis,X-ray crystal structure study,cytostatic and antiviral activity evaluations

A series of the novel acyclic unsaturated pyrimidine (1–12) and adenine (13) nucleoside analogues bearing conformationally restricted (Z)-2′-butenyl moiety were synthesized and evaluated for their antiviral and cytostatic activity potency against malignant tumor cell lines and normal human fibroblast (WI38). The N-1 and/or N-3 acyclic side chain substitution in pyrimidine ring in N-3 substituted 5-trifluoromethyluracil derivative (11), N-1, N-3 disubstituted 5-fluorouracil derivative (12) and adenine derivative (13) was deduced from their ¹H and ¹³C NMR spectra and confirmed by single crystal X-ray structure analysis. The X-ray crystal structure analysis 11–13 revealed also supramolecular self-assemblies, in which infinite chains or dimers built two- and three-dimensional networks. The results of the in vitro cytostatic activity evaluations of 1–13 indicate that the majority of the compounds tested exhibited a non-specific and moderate antiproliferative effect at the highest concentration (100 μM). Of all evaluated compounds on the cell lines tested only the N-1 4″-fluoro-substituted-benzamide uracil derivative (7) showed rather marked and selective inhibitory activity against the growth of MCF-7 cells at a concentration of 2.7 μM and no cytotoxic effect on normal fibroblasts WI38. This compound can be therefore considered as a potential antitumor lead compound for further synthetic structure modification.     

Long‐term regeneration of a tropical plant community after sand mining

Sandy coastal plant communities in tropical regions have been historically under strong anthropic pressure. In Brazil, these systems shelter communities with highly plastic plant species. However, the potential of these systems to regenerate without human assistance after disturbances has hardly been examined. We determined the natural regeneration of a coastal sandy plain vegetation (restinga) in Brazil, 16 years after the end of sand removal. We inventoried 38 plots: 20 within a sand‐mined site and 18 in an adjacent undisturbed site. We expected lower diversity values in the sand‐mined site compared to the undisturbed site, but similar species composition between the two sites due to the spatial proximity of the two sites and the high plasticity of restinga species. Species were ranked using abundance and importance value index in both sites, and comparisons were performed using Rényi entropy profiles, rarefaction curves, principal component analysis, and redundancy analysis. Species composition and dominant species differed markedly between the two sites. Bromeliads and Clusia hilariana, well‐known nurse plants, dominated the undisturbed site but were almost absent in the regenerating site. Species richness did not differ between both sites, but diversity was higher in the undisturbed site. Within‐site composition differences in the mined area were associated with field characteristics. Interestingly, species classified as subordinate or rare in the undisturbed site became dominants in the regenerating site. These newer dominants in the sand‐mined site are not those known as nurse plants in other restingas, thus yielding strong implications for restoration.     

Systems approach to studying animal sociality: individual position versus group organization in dynamic social network models

Social networks can be used to represent group structure as a network of interacting components, and also to quantify both the position of each individual and the global properties of a group. In a series of simulation experiments based on dynamic social networks, we test the prediction that social behaviors that help individuals reach prominence within their social group may conflict with their potential to benefit from their social environment. In addition to cases where individuals were able to benefit from improving both their personal relative importance and group organization, using only simple rules of social affiliation we were able to obtain results in which individuals would face a trade-off between these factors. While selection would favor (or work against) social behaviors that concordantly increase (or decrease, respectively) fitness at both individual and group level, when these factors conflict with each other the eventual selective pressure would depend on the relative returns individuals get from their social environment and their position within it. The presented results highlight the importance of a systems approach to studying animal sociality, in which the effects of social behaviors should be viewed not only through the benefits that those provide to individuals, but also in terms of how they affect broader social environment and how in turn this is reflected back on an individual's fitness.     

The validity of ESIN method of osteosynthesis compared to other active surgical methods of treatment of diaphyseal fractures of long bones in children and adolescents

We investigated the relationship of efficiency in the application of the ESIN method of intramedullary osteosynthesis and other active surgical methods in the treatment of diaphyseal fractures of long bones in children and adolescents. The study comprised 100 subjects treated by elastic stable intramedullary osteosynthesis (ESIN - group A) and 50 subjects in whom other active surgical methods were applied (group B). The following criteria of efficiency of treatment were applied: 1. length of perioperative hospitalization, 2. time elapsed since the operation until the beginning of loading of the traumatized extremity, 3. time elapsed since the operation until the full loading of the extremity, i.e. until the recovery of the fracture, 4. incidence of complications, 5. number of post-operative outpatient clinical visits until the recovery of the fracture and 6. overall number of X-ray images of the fractured bone since the accident until the coalescence of the fracture. The results obtained in both groups were compared. 1. The length of perioperative hospitalization is shorter in patients in whom ESIN method was applied. The difference between arithmetic means was 4.45 days and is statistically significant (p < 0.001). 2. The time between the operation until the beginning of loading of the extremity is shorter in patients subjected to ESIN method of osteosynthesis, the difference of mean values being 23.49 days and is statistically significant (p < 0.001). 3. The time between the operation until the full loading of the extremity is shorter in patients subjected to ESIN method of osteosynthesis, the difference being 16.6 days and is statistically significant (p < 0.001). 4. The number of complications in patients treated by the ESIN method of osteosynthesis is not statistically different from that in group B (chi2 = 0.25, p = 0.62). 5. In postoperative period there were fewer outpatient controls in patients to whom ESIN method of osteosynthesis was applied, and the difference is statistically significant (Z = 7.69, p < 0.001). 6. Likewise, the overall number of X-ray controls was lesser (Z = 8.06, p < 0.001). The results of examining the above parameters point to a greater efficiency of treating diaphyseal fractures of long bones in children and adolescents by the ESIN method of osteosynthesis, compared to other active surgical methods.