375 research outputs found

    A kinematic and computational study of leech crawling: Support for a CPG based on travelling waves of excitation.

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    Many well characterized central pattern generators (CPGs) underlie behaviors (e.g., swimming, flight, heartbeat) that require regular rhythmicity and strict phase relationships. Here, we examine the organization of a CPG for leech crawling, a behavior whose success depends more on its flexibility than on its precise coordination. We examined the organization of this CPG by first characterizing the kinematics of crawling steps in normal and surgically manipulated animals, then by exploring its features in a simple neuronal model. The behavioral observations revealed the following. (1) Intersegmental coordination varied considerably with step duration, whereas the rates of elongation and contraction within individual segments were relatively constant. (2) Steps were generated in the absence of both head and tail brains, implying that midbody ganglia contain a CPG for step production. (3) Removal of sensory feedback did not affect step coordination or timing. (4) Imposed stretch greatly lengthened transitions between elongation and contraction, indicating that sensory pathways feed back onto the CPG. A simple model reproduced essential features of the observed kinematics. This model consisted of an oscillator that initiates propagating segmental waves of activity in excitatory neuronal chains, along with a parallel descending projection; together, these pathways could produce the observed intersegmental lags, coordination between phases, and step duration. We suggest that the proposed model is well suited to be modified on a step-by-step basis and that crawling may differ substantially from other described CPGs, such as that for swimming in segmented animals, where individual segments produce oscillations that are strongly phase-locked to one another

    Changes in Macrozoobenthos Community after Aquatic Plant Restoration in the Northern Venice Lagoon (IT)

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    Responses of the macrozoobenthic community to an ecological restoration activity in the northern Venice lagoon were studied, within the scope of the project LIFE SEagrass RESTOration aimed at recreating aquatic phanerogam meadows largely reduced in recent decades. Transplants were successful in almost all project areas. Macrozoobenthos was sampled in eight stations before (2014) and after (2015, 2016, 2017) transplanting activities. An increase in abundance and fluctuations in richness and univariate ecological indices (Shannon’s, Margalef’s, Pielou’s indices) resulted during the years. Comparing non-vegetated and vegetated samples in 2017, every index except Pielou’s increased in the latter. Multivariate analysis (hierarchical cluster analysis, MDS, PERMDISP, SIMPER) grouped samples by localization rather than years, with differences between stations due to the abundance of common species. In 2017, results were also grouped by the presence or absence of aquatic plants, with differences in the abundance of grazer and filter-feeding species. Results of ecological index M-AMBI depicted conditions from moderate to good ecological status (sensu Dir.2000/60/EC) with similar fluctuations, as presented by univariate indices from 2014 to 2017. Responses of the macrozoobenthic community were more evident when comparing vegetated and non-vegetated samples, with the vegetated areas sustaining communities with greater abundance and diversity than non-vegetated samples, thus demonstrating the supporting function of aquatic plants to benthic communities

    BILATERAL RENAL ARTERY STENOSIS IN A HYPERTENSIVE LUPUS PATIENT WITHOUT RENAL DYSFUNCTION: A CASE REPORT

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    Systemic lupus erythematosus (SLE) is associated with a high prevalence of atherosclero-sis and an enhanced cardiovascular mortality. In adult subjects, several studies have shown the coexistence of SLE and renal artery stenosis, most of them with unilateral in-volvement or with renal dysfunction. We observed a 62-year-old man with SLE and a 10-year history of moderate-to-severe hy-pertension who was admitted to our hospital because of uncontrolled blood pressure val-ues (152/95 mmHg), despite drug therapy. No signs of renal impairment were evident. After an initial physical examination, which presented a periumbilical bruit, a renal ultra-sound was performed with evidence of bilateral renal artery stenosis. An angio-MR study also confirmed the diagnosis and showed a double renal artery on the right side. Many different factors can contribute to the bilateral renal artery stenosis in this patient. Chronic inflammatory state associated to SLE, metabolic alterations with dyslipidemia and steroid therapy may all be involved in the development of the renal atherosclerotic le-sions

    Balance between the reliability of classification and sampling effort: A multi-approach for thewater Framework Directive (WFD) ecological status applied to the Venice Lagoon (Italy)

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    The Water Framework Directive (WFD) requires Member States to assess the ecological status of water bodies and provide an estimation of the classification confidence and precision. This study tackles the issue of the uncertainty in the classification, due to the spatial variability within each water body, proposing an analysis of the reliability of classification, using the results of macrophyte WFD monitoring in the Venice Lagoon as case study. The level of classification confidence, assessed for each water body, was also used as reference to optimize the sampling effort for the subsequent monitorings. The ecological status of macrophytes was calculated by the Macrophyte Quality Index at 114 stations located in 11 water bodies. At water body scale, the level of classification confidence ranges from 54% to 100%. After application of the multi-approach (inferential statistics, spatial analyses, and expert judgment), the optimization of the sampling effort resulted in a reduction of the number of stations from 114 to 84. The decrease of sampling effort was validated by assessing the reliability of classification after the optimization process (54-99%) and by spatial interpolation of data (Kernel standard error of 22.75%). The multi-approach proposed in this study could be easily applied to any other water body and biological quality element

    Switch to restoration therapy in a testosterone treated central hypogonadism with erythrocytosis

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    We describe a case of severe erythrocytosis caused by testosterone replacement therapy in a 66-year-old man affected with hypogonadotropic hypogonadism (HH) determining osteoporosis, resolved by switching to restoration therapy with clomiphene citrate. The patient complained fatigue, loss of libido and defective erections and a spontaneous vertebral fracture despite bisphosphonate therapy and vitamin D supplementation. The examinations proved isolated HH and he was therefore treated with testosterone gel with regression of specific manifestations but elevated hemoglobin and hematocrit values. Therefore, it was decided to switch to a restoration therapy with clomiphene citrate 25\u2009mg/die, which resulted in the resolution of symptoms without evident side effects. In a couple of months, the patient showed normalization of testosterone levels and increment of testicular volume. Since secondary hypogonadism is the consequence of an insufficient stimulation of the gonads by hypothalamic-pituitary axis, therapeutic approaches aimed to restore endogenous testosterone production should be considered in alternative to testosterone replacement, particularly if side effects intervene. Among these strategies, clomiphene citrate seems to have a high efficacy and safety profile also in the elderly with isolated HH and no evident pituitary lesion

    Conservation actions for restoring the coastal lagoon habitats: Strategy and multidisciplinary approach of LIFE Lagoon Refresh

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    The Habitat Directive of European Union lists Costal Lagoons (habitat code 1150*) among priority habitats because they are in danger of disappearance. Natural ecosystems may recover from anthropogenic perturbations; however, the recovery can follow natural restoration or it can be redirected through ecological restoration by anthropogenic intervention. Accordingly, by collecting the available theoretical indications for restoration of estuarine and coastal areas, a methodological approach was detailed andit can be summarised into five issues: (i) Environmental context from which it began; (ii) Desired state to be achieved; (iii) Policies and socio-economic context; (iv) Typology of recovery and/or improvement of habitats and ecosystems; and (v) Methods for monitoring the impact of the project. The project strategy, management and measures of LIFE Lagoon Refresh were also presented and discussed, as a case study for the implementation of the multidisciplinary approach for restoration ecology in transitional waters. The project takes place in the northern Venice Lagoon (Italy), started in 2017 and it lasts 5 years. In the Venice Lagoon, since the 20th century, strong reductions of the typical salinity gradient of buffer areas between lagoon and mainland, and of reedbed extensions have occurred due to historic human interventions, with negative consequences on coastal lagoon habitats. To improve the conservation status of habitats and biodiversity of the area, the LIFE Lagoon Refresh project included several conservative actions, which are (i) the diversion of a freshwater flow from the Sile River into the lagoon; (ii) the restoration of intertidal morphology, through biodegradable structures; (iii) the reed and aquatic angiosperm transplantations with the involvement of local fishermen and hunters, and (iv) the reduction of hunting and fishing pressures in the intervention area. To achieve the restoration of the lagoon environment, the strategy of the project covered a combination of different aspects and tools, such as planning activities, through the involvement of local Institutions and communities; stakeholder's involvement to increase awareness of environment conservation and socioeconomic value improvement; an ecological engineering approach; numerical models as supporting tool for planning and managing of conservation actions; environmental monitoring performed before and after the conservation actions
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