1,095 research outputs found

    Mechanism of development of pre-eclampsia linking breathing disorders to endothelial dysfunction

    Get PDF
    High blood pressure is an important component of pre-eclampsia. The underlying mechanism of development of hypertension in pre-eclampsia is complicated and still remains obscure. Several theories have been advanced including endothelial dysfunction, uteroplacental insufficiency leading to generalized vasoconstriction, increased cardiac output, and sympathetic hyperactivity. Increased blood flow and pressure are thought to lead to capillary dilatation, which damages end-organ sites, leading to hypertension, proteinuria and edema. Additional theories have been put forward based on epidemiological research, implicating immunological and genetic factors. None of these theories have been substantiated. Based on a review of literature this paper postulates that the initiating event for the development of preeclampsia is intermittent hypoxia associated with irregular breathing during sleep, hypoapnea, apnea,inadequate respiratory excursions during the waking hours and inadequate cardiopulmonary synchronization (abnormal sympatho-vagal balance)

    Propane Dehydrogenation Using Transition Metal Cluster Catalysts

    Get PDF
    Our research seeks to determine the propane dehydrogenation (PDH) reaction pathways using various transition-metal cluster catalysts. We are studying the first step of the reaction, in which a C-H bond is broken. This has been previously shown to be the rate-limiting step of the PDH reaction. We are calculating the PDH activation energy (Ea) using the Vienna Ab-Initio Simulation Package (VASP) in conjunction with the nudged elastic band algorithm. Thus far, we have studied Pt, Ta, and Ni clusters ranging in size from 2-10 atoms. Our goal is to better understand the dependence of Ea on metal type and cluster size

    A Pricing-Based Cooperative Spectrum Sharing Stackelberg Game

    Full text link
    We consider the problem of cooperative spectrum sharing among a primary user (PU) and multiple secondary users (SUs) under quality of service (QoS) constraints. The SUs network is controlled by the PU through a relay which gets a revenue for amplifying and forwarding the SUs signals to their respective destinations. The relay charges each SU a different price depending on its received signal-to-interference and-noise ratio (SINR). The relay can control the SUs network and maximize any desired PU utility function. The PU utility function represents its rate, which is affected by the SUs access, and its gained revenue to allow the access of the SUs. The SU network can be formulated as a game in which each SU wants to maximize its utility function; the problem is formulated as a Stackelberg game. Finally, the problem of maximizing the primary utility function is solved through three different approaches, namely, the optimal, the heuristic and the suboptimal algorithms.Comment: 7 pages. IEEE, WiOpt 201

    Detection of Chlamydia trachomatis and Mycoplasma hominis, genitalium and Ureaplasma urealyticum by polymerase chain reaction in patients with sterile pyuria

    Get PDF
    Purpose: Chlamydia trachomatis and Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma urealyticum are associated with various diseases of the urogenital tract, but they are usually not detected by routine microbiological diagnosis

    Endothelial cell apoptosis in chronically obstructed and reperfused pulmonary artery

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Endothelial dysfunction is a major complication of pulmonary endarterectomy (PTE) that can lead to pulmonary edema and persistent pulmonary hypertension. We hypothesized that endothelial dysfunction is related to increased endothelial-cell (EC) death.</p> <p>Methods</p> <p>In piglets, the left pulmonary artery (PA) was ligated to induce lung ischemia then reimplanted into the main PA to reperfuse the lung. Animals sacrificed 5 weeks after ligation (n = 5), 2 days after reperfusion (n = 5), or 5 weeks after reperfusion (n = 5) were compared to a sham-operated group (n = 5). PA vasoreactivity was studied and eNOS assayed. EC apoptosis was assessed by TUNEL in the proximal and distal PA and by caspase-3 activity assay in the proximal PA. Gene expression of pro-apoptotic factors (thrombospondin-1 (Thsp-1) and plasminogen activator inhibitor 1 (PAI-1)) and anti-apoptotic factors vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) was investigated by QRT-PCR.</p> <p>Results</p> <p>Endothelium-dependent relaxation was altered 5 weeks after ligation (<it>p </it>= 0.04). The alterations were exacerbated 2 days after reperfusion (p = 0.002) but recovered within 5 weeks after reperfusion. EC apoptosis was increased 5 weeks after PA ligation (<it>p </it>= 0.02), increased further within 2 days after reperfusion (<it>p </it>< 0.0001), and returned to normal within 5 weeks after reperfusion. Whereas VEGF and bFGF expressions remained unchanged, TSP and PAI-1 expressions peaked 5 weeks after ligation (<it>p </it>= 0.001) and returned to normal within 2 days after reperfusion.</p> <p>Conclusion</p> <p>Chronic lung ischemia induces over-expression of pro-apoptotic factors. Lung reperfusion is followed by a dramatic transient increase in EC death that may explain the development of endothelial dysfunction after PE. Anti-apoptotic agents may hold considerable potential for preventing postoperative complications.</p

    HEAVY METALS IN CULTIVATED SOIL AND PLANTS OF DAMOUR URBAN AREA - LEBANON

    Get PDF
    Παρουσιάζονται για πρώτη φορά δεδομένα συγκεντρώσεων βαρέων μετάλλων στο έδαφος και καλλιέργειες της περιοχής Νταμούρ Λιβάνου. Μετρήθηκαν οι ψευδοολικές και κινητοποιήσιμες συγκεντρώσεις των Zn, Cu, Ni, Cr, Co, Mn, Fe, Ba, Pb και Cd σε δείγματα εδαφών καθώς και οι αντίστοιχες ολικές συγκεντρώσεις των ίδιων στοιχείων σε φυτικούς ιστούς λαχανικών που καλλιεργούνται στην περιοχή Δεν ανιχνεύθηκαν συγκεντρώσεις των μη απαραίτητων στοιχείων Pb και Asενώ αυτές των υπόλοιπων στοιχείων που μελετήθηκαν βρίσκονται εντός των φυσιολογικών ορίων. Οι συγκεντρώσεις στο έδαφος φαίνεται να επηρεάζονται από την προηγούμενη χρήση γης και αυτές στα φυτά φαίνεται να ρυθμίζονται μέσω της λειτουργίας σύνθετων μεταβολικών μηχανισμών.Preliminary data on heavy metals concentrations in soil and edible plants of DamourLebanon are presented for the first time. Concentration ranges of Zn, Cu, Ni, Cr, Co, Mn, Fe, Ba, Pb and Cd in soils and vegetables collected from urban allotments in Damour were determined and assessed taking into account the pseudototal (extracted by aqua regia) and mobilizable (0.43 M acetic acid extractable) concentrations of the elements in the rhizosphere soil of the plants as well as the total concentrations in edible plant tissue. Average elemental concentrations in urban allotments are low in general. No detectable concentrations of the non-essential heavy metals Pb and As were measured in the studied plants while concentrations of micronutrient elements in plants were within normal ranges. The collected data indicate that previous land use is an important factor controlling heavy metal content in soil and that there is a complex mechanism controlling micronutrient uptake by plants

    Climate-driven hydrological change and carbonate platform demise induced by the Paleocene–Eocene Thermal Maximum (southern Pyrenees)

    Get PDF
    The Campo section in the Spanish Pyrenees is classical for shallow-water Paleocene-Eocene Thermal Maximum (PETM) studies. Despite extensive work in the last decades, the stratigraphic location of the onset of the negative carbon isotope excursion (CIE), and hence the Paleocene/Eocene (P/E) boundary, remains a matter of considerable debate in the Campo section. Here we present new biostratigraphic, sedimentological and carbon-isotopic data across the late Paleocene to Eocene strata to constrain the precise stratigraphic position of the P/E boundary and investigate environmental changes across the PETM. Foraminiferal assemblages of biozone SBZ4 found below the Claret Formation are replaced by SBZ6 assemblages above. Detailed microfacies analysis indicated that the pre-PETM upper Navarri Formation represents transgressive inner-ramp deposits, overlain unconformably by mixed carbonate-siliciclastic deposits of the syn-PETM Claret Formation, overlain unconformably in turn by renewed carbonate-ramp deposition in the post-PETM lower Serraduy Formation. The temporary demise of the carbonate ramp during the PETM is ascribed to increased siliciclastic supply associated with a significant change in regional hydrology driven by an increase in magnitude and frequency of extreme rainfall and runoff events

    Shallow-water carbonate responses to the Paleocene–Eocene thermal maximum in the Tethyan Himalaya (southern Tibet): Tectonic and climatic implications

    Get PDF
    This study presents a detailed stratigraphic record of the Paleocene–Eocene Thermal Maximum (PETM) in the Gamba area of the Tethyan Himalaya, a carbonate-platform succession originally deposited along the southern margin of the eastern Tethys Ocean. The Paleocene-Eocene boundary interval is marked by a negative carbon isotope excursion at the boundary between members 3 and 4 of the Zongpu Formation. The succession is erosionally truncated at this surface, which is overlain by an intraformational carbonate conglomerate, and only the upper part of the PETM interval is preserved. Foraminiferal assemblages of Shallow Benthic Zone 4 are present below the conglomerate bed, but are replaced by assemblages of Shallow Benthic Zone 6 above the conglomerate. Depositional facies also change across this surface; below the disconformity, floatstones and packstones containing nummulitid forams record progressive transgression in an open-marine environment, whereas restricted or lagoonal inner-ramp deposits containing Alveolina and Orbitolites are typical above the disconformity. The prominent negative excursion observed in the δ13C of whole-rock carbonate (− 1.0‰ at Zongpu, − 2.4‰ at Zengbudong) and organic matter (− 24.7‰, at Zengbudong) is correlated to the characteristic PETM carbon isotope excursion. This major negative excursion in shallow-marine carbonates may have partly resulted from syndepositional alteration of organic matter. The erosional unconformity can be constrained to the lower PETM interval (between 56 and 55.5 Ma), and is identifiable throughout the Tethyan Himalaya. This widespread disconformity is attributable to tectonic uplift associated with the southward migration of an orogenic wave, originated 3 ± 1 Ma earlier in the middle Paleocene at the first site of India-Asia continent-continent collision. A possible eustatic component of the pre-PETM sea-level fall, which resulted in the excavation of incised valleys filled during the subsequent sea-level rise when the conglomerate bed was deposited, remains to be assessed

    Brief mindfulness training enhances cognitive control in socioemotional contexts: Behavioral and neural evidence.

    Get PDF
    In social contexts, the dynamic nature of others' emotions places unique demands on attention and emotion regulation. Mindfulness, characterized by heightened and receptive moment-to-moment attending, may be well-suited to meet these demands. In particular, mindfulness may support more effective cognitive control in social situations via efficient deployment of top-down attention. To test this, a randomized controlled study examined effects of mindfulness training (MT) on behavioral and neural (event-related potentials [ERPs]) responses during an emotional go/no-go task that tested cognitive control in the context of emotional facial expressions that tend to elicit approach or avoidance behavior. Participants (N = 66) were randomly assigned to four brief (20 min) MT sessions or to structurally equivalent book learning control sessions. Relative to the control group, MT led to improved discrimination of facial expressions, as indexed by d-prime, as well as more efficient cognitive control, as indexed by response time and accuracy, and particularly for those evidencing poorer discrimination and cognitive control at baseline. MT also produced better conflict monitoring of behavioral goal-prepotent response tendencies, as indexed by larger No-Go N200 ERP amplitudes, and particularly so for those with smaller No-Go amplitude at baseline. Overall, findings are consistent with MT's potential to enhance deployment of early top-down attention to better meet the unique cognitive and emotional demands of socioemotional contexts, particularly for those with greater opportunity for change. Findings also suggest that early top-down attention deployment could be a cognitive mechanism correspondent to the present-oriented attention commonly used to explain regulatory benefits of mindfulness more broadly
    corecore