Association Patterns in Saproxylic Insect Networks in Three Iberian Mediterranean Woodlands and Their Resistance to Microhabitat Loss

The assessment of the relationship between species diversity, species interactions and environmental characteristics is indispensable for understanding network architecture and ecological distribution in complex networks. Saproxylic insect communities inhabiting tree hollow microhabitats within Mediterranean woodlands are highly dependent on woodland configuration and on microhabitat supply they harbor, so can be studied under the network analysis perspective. We assessed the differences in interacting patterns according to woodland site, and analysed the importance of functional species in modelling network architecture. We then evaluated their implications for saproxylic assemblages’ persistence, through simulations of three possible scenarios of loss of tree hollow microhabitat. Tree hollow-saproxylic insect networks per woodland site presented a significant nested pattern. Those woodlands with higher complexity of tree individuals and tree hollow microhabitats also housed higher species/interactions diversity and complexity of saproxylic networks, and exhibited a higher degree of nestedness, suggesting that a higher woodland complexity positively influences saproxylic diversity and interaction complexity, thus determining higher degree of nestedness. Moreover, the number of insects acting as key interconnectors (nodes falling into the core region, using core/periphery tests) was similar among woodland sites, but the species identity varied on each. Such differences in insect core composition among woodland sites suggest the functional role they depict at woodland scale. Tree hollows acting as core corresponded with large tree hollows near the ground and simultaneously housing various breeding microsites, whereas core insects were species mediating relevant ecological interactions within saproxylic communities, e.g. predation, competitive or facilitation interactions. Differences in network patterns and tree hollow characteristics among woodland sites clearly defined different sensitivity to microhabitat loss, and higher saproxylic diversity and woodland complexity showed positive relation with robustness. These results highlight that woodland complexity goes hand in hand with biotic and ecological complexity of saproxylic networks, and together exhibited positive effects on network robustness.The research Projects I+D CGL2011-23658 y CGL2012-31669 of the Spanish Minister of Science provided economic support

Sympatho-adrenergic inhibition of basal and acid-induced changes in duodenal motility, mucosal net fluid and alkaline secretion in the anaesthetized cat

Experiments were performed on chloralose anaesthetized cats. A 2-cm segment of the proximal duodenum was isolated between two luminally situated balloons and perfused with isotonic saline containing [14C]-PEG 4000 as a non-absorbable marker. The perfusate was analysed with regard to alkalinity (back titration) and concentration of marker (liquid scintillation). Net alkalinization and net fluid transport were calculated with conventional equations. Motor activity in the duodenal wall was recorded as changes in volume of the proximal balloon. In presence of sympathetic neural activity (spontaneous or electrically stimulated) basal motor activity and mucosal alkaline secretion was low and increased minimally in response to luminal HCl (30 mM). Net fluid transport was in an absorptive state and shifted to a small secretion upon the acid-exposure. Subsequent to bilateral acute splanchnicotomy, or the administration of the adrenolytic guanethidine (3-4 mg kg-1, i.v.), spontaneous duodenal contractions occurred and the alkaline secretion was increased. Furthermore, both parameters were then markedly stimulated by luminal perfusion with 30 mM HCl. Basal net fluid transport was zero and turned into secretion upon the acid-exposure. No morphological changes of the duodenal surface epithelium could be detected. The study demonstrates the existence of splanchnic nerve-mediated, adrenergic inhibition of basal, as well as of acid-induced duodenal motility, fluid and alkaline secretion

Magnification endoscopy for diagnosis of nonerosive reflux disease: a proposal of diagnostic criteria and critical analysis of observer variability

This study tested the diagnostic value of high-resolution endoscopy for the recognition of subtle diagnostic esophageal mucosal changes in nonerosive reflux disease. Ten control subjects and eleven patients with nonerosive reflux disease confirmed by a validated questionnaire, standard endoscopy, and 24-hour pH-metry participated in the study. Still images were collected by high-resolution endoscopes from the distal esophagus in a standardized manner, incorporating iodine staining. Assessments were repeated in the patients with reflux disease after 4 weeks of esomeprazole therapy. Interobserver variability in the recognition of the proposed criteria was initially evaluated by 27 endoscopists using an Internet-based process. After optimisation of image quality the evaluation was repeated face-to-face with six expert endoscopists. No criterion was identified in either assessment that was sufficiently sensitive and specific to patients with reflux disease to be clinically useful. The kappa value, used to assess interobserver variation, was acceptably high only for invisibility of palisade vessels (0.59). Triangular indentations, apical mucosal breaks, and pinpoint blood vessels at the squamocolumnar junction were identified more frequently in the patients with reflux disease ( P < 0.05). These changes and the invisibility of the palisade vessels were significantly less prevalent in reflux patients after therapy ( P < 0.01). Though some distal esophageal mucosal appearances observed with the high-resolution endoscope appeared to be related to nonerosive esophageal mucosal injury, none of these changes proved to be sufficiently sensitive and specific to justify their use as a diagnostic criterion for nonerosive reflux diseas