Noise effects on robust synchronization of a small pacemaker neuronal ensemble via nonlinear controller: electronic circuit design

In this paper, we report on the synchronization of a pacemaker neuronal ensemble constituted of an AB neuron electrically coupled to two PD neurons. By the virtue of this electrical coupling, they can fire synchronous bursts of action potential. An external master neuron is used to induce to the whole system the desired dynamics, via a nonlinear controller. Such controller is obtained by a combination of sliding mode and feedback control. The proposed controller is able to offset uncertainties in the synchronized systems. We show how noise affects the synchronization of the pacemaker neuronal ensemble, and briefly discuss its potential benefits in our synchronization scheme. An extended Hindmarsh–Rose neuronal model is used to represent a single cell dynamic of the network. Numerical simulations and Pspice implementation of the synchronization scheme are presented. We found that, the proposed controller reduces the stochastic resonance of the network when its gain increases.     

Chromosomal aberrations in patients with primary biliary cirrhosis

Summary Chromosomal aberrations in untreated lymphocyte cultures, bleomycin (BLM)-induced aberrations and sister chromatid exchanges (SCE) in the peripheral blood lymphocytes of 11 patients suffering from primary biliary cirrhosis (PBC) and 14 matched control individuals were analysed. The lymphocytes of the PBC patients had on average a lower mitotic index (2.3) compared with controls (3.5) in the untreated cultures. The mean baseline rate of aberrations of the cultured lymphocytes of the patients was 5.3 aberrations per 100 metaphases (%); this was significantly different (P=0.0291) from that of the controls with a mean of 2.3%. In lymphocytes of the patients and controls, most of the aberrations observed took the form of gaps; there was an almost equal breakage rate in both groups (0.5% and 0.4%, respectively). The average number of mitoses with aberrations in the PBC patients studied was double that of the controls (4.9% and 2.3% respectively, P=0.0323). The mean number of the BLM-induced aberrations was 54.0% and 27.7% for the lymphocytes of the patients and controls, respectively. The mean number of the aberrant mitoses in the BLM cultures was 6 times higher than that of the untreated cultures for both groups, 25.7% and 14.6% respectively (P=0.018). The chromosomal distribution of baseline and induced aberrations was not random. The PBC patients had a mean number of 8.7 SCE per mitosis, which was significantly higher than the SCEs in the controls (6.3 SCE per mitosis; P=0.0156). The evidence suggests that the chromosomes of the lymphocytes of PBC patients may be less stable than those of the control individuals in this study.     

Interaction between rat alpha 1 fetoprotein and fluorescent derivatives of estrone in relation to the position and type of the fluorescent label

A series of derivatives of estrone with fluorescent dyes (dansyl or coumarin) coupled at different positions on the steroid molecule, have been synthesized. These derivatives were tested for their quantum yields and their binding properties were determined with respect to rat alpha 1 fetoprotein. Derivatives at C-3 (estrone-3-hemisuccinate-dansyl-cadaverine and estrone-3-dansyl) compete with estrone for binding to the fetal protein; however derivates of estrone at C-6 (estrone-6-carboxymethyloxime-dansyl-cadaverine) and at C-17 (estrone-17-carboxymethyloxime-coumarine, estrone-17-carboxymethyloxime-dansyl-cadaverine and estrone-17-dansyl-hydrazine) compete poorly or not at all. The association constant of the radioactive derivative estrone-3-dansyl [3H] with rat alpha 1 fetoprotein was measured directly: the same number of high affinity binding sites (0.6) as that for estrone was found with an apparent association constant of 3.7 X 10(6) M-1. In addition to the high affinity binding sites, a low affinity class of binding sites was found which corresponds to the binding of the dansyl fraction of the fluorescent steroid derivative.     

Immunofluorescent localization of collagens,fibronectin, and laminin during terminal differentiation of odontoblasts

The localization of collagens types I, II, III, IV, laminin, and fibronectin was analyzed in mouse embryonic molars by indirect immunofluorescence. Using affinity-purified antibodies, all these antigens except collagen type II were detected in tooth germs and particularly at the epithelio-mesenchymal junction. Collagens type I, type IV, and laminin were localized at the junction before, during, and after odontoblasts terminal differentiation. The staining patterns corresponding to type III collagen and fibronectin were modified during the polarization of odontoblasts. Collagen type III present at the epithelio-mesenchymal junction could no longer be detected in this region when odontoblasts were polarized. Fibronectin, surrounding preodontoblasts, was confined to the epithelio-mesenchymal junction when odontoblasts were fully polarized. Previous studies had shown that the presence of a basement membrane and associated material was a prerequisite for the polarization of odontoblasts. Therefore, the redistribution of collagen type III and fibronectin was discussed in terms of fibronectin-collagen interactions and transmembranous control of the cytoskeleton activity in the differentiating odontoblasts.     

Serological reactivity of baculovirus-expressed Ebola virus VP35 and nucleoproteins

Ebola virus (EBOV) is a member of the family Filoviridae and is classified as a biosafety level 4 virus. This classification makes the preparation of antigen and performance of diagnostic assays time-consuming and complicated. The objective of this study was to evaluate the value of EBOV immunoassays based on recombinant nucleoprotein (r-NP) and recombinant VP35 (r-VP35) using large serum panels of African origin and from primates. Furthermore, we investigated whether the results obtained with EBOV r-VP35 enzyme-linked immunosorbent assay (ELISA) could improve on the findings obtained with the EBOV r-NP ELISA. The full-length EBOV NP and VP35 of the EBOV subtype Zaire were expressed as histidine-tagged recombinant proteins in the baculovirus expression system. The antigenic reactivity and specificity of these recombinant proteins were determined by Western blotting and ELISA using EBOV specific monoclonal antibodies. The results obtained with the r-NP and r-VP35 ELISAs were compared with the results obtained in an indirect immunofluorescence assay based on native EBOV subtype Zaire. EBOV specific monoclonal antibodies reacted specifically with the respective proteins in both Western blot and ELISA. Five hundred and twenty six samples from humans and primates were tested with r-NP and r-VP35 ELISAs. Monkey serum samples positive for EBOV subtype Reston and Zaire were both positive in the EBOV r-NP ELISA, whereas only the EBOV Zaire infected monkeys were positive in the r-VP35 ELISA. The sensitivity and specificity values of the EBOV recombinants' ELISAs compared to those of the immunofluorescence assay were 92% and 99% for r-NP and 44% and 100% for r-VP35. r-NP ELISA proved to be a sensitive and specific assay for EBOV diagnosis and for epidemiological studies for both EBOV subtypes Reston and Zaire. The use of r-VP35 in an ELISA format has no additional value for EBOV serodiagnosis.     

Dynamics and metabolic activity of the benthic cyanobacterium Microcystis aeruginosa in the Grangent reservoir (France)

The dynamics of benthic colonies of Microcystis aeruginosa (cyanobacteria)play an important part in the formation of the summer bloomunderlying many harmful effects. Because this benthic phaseremains somewhat unknown, we developed an approach using flowcytometry to follow the esterase activity of this species inthe Grangent reservoir. The esterase activity of benthic cyanobacteriaextracted from two layers of sediment (0–2 cm and 2–4cm deep) was measured weekly, as an indicator of viability,by flow cytometry with carboxyfluorescein diacetate. In parallel,the concentration of benthic cyanobacteria was estimated underepifluorescence microscopy and the water temperature and dissolvedoxygen concentration were measured in the hypolimnion. Esteraseactivity increased gradually as spring temperatures increased.This metabolic reactivation allowed one part of the benthiccyanobacteria to regain the water column, entailing a simultaneousdecrease of their number in the upper sediment (0–2 cm).Then, after a maximum in summer, esterase activity decreasedwhile the number of colonies increased. This corresponded withthe domination of the senescent planktonic form following thedecline of the bloom.     

Increasing temperature may compensate for lower amounts of dead wood in driving richness of saproxylic beetles

Global warming and land‐use change are expected to be additive threats to global diversity, to which insects contribute the highest proportion. Insects are strongly influenced by temperature but also require specific habitat resources, and thus interaction between the two factors is likely. We selected saproxylic beetles as a model group because their life cycle depends on dead wood, which is highly threatened by land use. We tested the extent to which higher temperatures compensate for the negative effects of low amounts of dead wood on saproxylic beetle species richness (Temperature–Dead wood compensation hypothesis) on both a macroclimate and a topoclimate scale (north‐ and south‐facing slopes). We analyzed 1404 flight‐interception trap catches across Europe to test for interaction effects of temperature and dead‐wood amount on species richness. To experimentally test our findings from the activity trap data, we additionally reared beetles from 80 bundles of dead wood initially exposed at high and low elevations. At the topoclimate scale, we analyzed trap catches and reared beetles from dead wood exposed in 20 forest stands on south‐facing and north‐facing slopes in one region. On the macroscale, both temperature and dead‐wood amount positively affected total and threatened species richness independently, but their interaction was significantly negative, indicating compensation. On both scales and irrespective of the method, species richness decreased with temperature decline. Our observation that increasing temperature compensates for lower amounts of dead wood has two important implications. First, managers of production forests should adapt their dead‐wood enrichment strategy to site‐specific temperature conditions. Second, an increase in temperature will compensate at least partially for poor habitat conditions in production forests. Such a perspective contrasts the general assumption of reinforcing impacts of global warming and habitat loss on biodiversity, but it is corroborated by recent range expansions of threatened beetle species.     

Application of a Hyaluronic Acid Gel after Intrauterine Surgery May Improve Spontaneous Fertility: A Randomized Controlled Trial in New Zealand White Rabbits

ObjectiveIntrauterine adhesions (IUAs) are the most common complication after hysteroscopy in patients of reproductive age. Intra-abdominal anti-adhesion gel reduces the incidence of adhesions, but effects on fertility after uterine surgery are not known. The objective of our work was to evaluate the effect of intrauterine anti-adhesion gel on spontaneous fertility after repeated intrauterine surgery with induced experimental synechiae in the rabbit model.ResultsThere was a significant difference in total fetuses in favor of group A, with an average of 3.7 (range, 0–9) total fetuses per tube against 2.1 (0–7) in group B (p = .04). The number of viable fetuses shows a trend in favor of group A, with an average of 3.4 (0–7) viable fetuses per tube against 1.9 (0–6) viable fetuses per tube in group B (p = .05).ConclusionThe use of immediate postoperative anti-adhesion gel improved fertility in an animal model after intrauterine surgery likely to cause uterine synechiae. This experimental model will permit comparison of different anti-adhesion solutions, including assessment of their tolerance and potential mucosal toxicity on embryonic development.     

Shifts in the height‐related competitiveness of tree species following recent climate warming and implications for tree community composition: the case of common beech and sessile oak as predominant broadleaved species in Europe

Height growth is a trait that contributes to tree species fitness. How height growth responds to environmental changes may therefore provide indications on species ability to compete and maintain, and on changes in tree community composition. Common beech Fagus sylvatica and sessile oak Quercus petraea are the predominant late‐successional broadleaved species in Europe, and they differ in their shade‐tolerance. On common beech (a shade tolerant species), recent observations across Europe have shown a growth decline during recent climate warming. Because sessile oak is a warmth‐ and light‐demanding species, we therefore hypothesised that it may gain in competitiveness relative to common beech. We conducted analyses of historical height growth in several regions spanning the distributional range of the two species across a temperate‐continental gradient in France. Common beech and sessile oak were sampled in two and four regions, respectively, and were compared in two neighbouring regions. We documented the climatic and nutritional conditions of regional samples. Height growth of 408 trees of various ages was reconstituted from stem analyses. We estimated 20th‐century regional chronologies of height growth using a statistical modelling approach that filtered out the effects of ontogeny and site fertility. In regions where both species were sampled, modelled height trajectories were compared at different periods over the 20th century. Growth chronologies revealed 1) long‐term growth rate increases of a magnitude of 50–100% over 100 years in both species, more acute in the continental domain, 2) recurrent historical inversions in growth fluctuations between species, 3) a recent divergence, with growth decline in common beech versus a dramatic growth increase in sessile oak, more acute in colder regions. The analysis of height trajectories indicated a recent reduction in common beech competitiveness relative to sessile oak. In the face of future climate warming, we conclude that increased prevalence of beech–oak mixtures may arise.