The meteorological surveillance of the four nuclear power plants in Switzerland is of first importance in a densely populated area such as the Swiss Plateau. The project "Centrales Nucléaires et ...Météorologie" CN-MET aimed at providing a new security tool based on one hand on the development of a high resolution numerical weather prediction (NWP) model. The latter is providing essential nowcasting information in case of a radioactive release from a nuclear power plant in Switzerland. On the other hand, the model input over the Swiss Plateau is generated by a dedicated network of surface and upper air observations including remote sensing instruments (wind profilers and temperature/humidity passive microwave radiometers). This network is built upon three main sites ideally located for measuring the inflow/outflow and central conditions of the main wind field in the planetary boundary layer over the Swiss Plateau, as well as a number of surface automatic weather stations (AWS). The network data are assimilated in real-time into the fine grid NWP model using a rapid update cycle of eight runs per day (one forecast every three hours). This high resolution NWP model has replaced the former security tool based on in situ observations (in particular one meteorological mast at each of the power plants) and a local dispersion model. It is used to forecast the dynamics of the atmosphere in the planetary boundary layer (typically the first 4 km above ground layer) and over a time scale of 24 h. This tool provides at any time (e.g. starting at the initial time of a nuclear power plant release) the best picture of the 24-h evolution of the air mass over the Swiss Plateau and furthermore generates the input data (in the form of simulated values substituting in situ observations) required for the local dispersion model used at each of the nuclear power plants locations. This paper is presenting the concept and two validation studies as well as the results of an emergency response exercise performed in winter 2009.
Canton Ticino in southern Switzerland is exposed to some of the highest concentrations of tropospheric ozone in Europe. During recent field surveys in Canton Ticino, foliar symptoms identical to ...those caused by ozone have been documented on native tree and shrub species. In Europe, the critical ozone level for forest trees has been defined at an AOT40 of 10 ppm.h O3 (10 ppm.h accumulated exposure of ozone over a threshold of 40 ppb) during daylight hours over a six-month growing season. The objective of this study was to determine the amount of ambient ozone required to induce visible foliar symptoms on various forest plant species in southern Switzerland. Species were grown within eight open-top chambers and four open plots at the Vivaio Lattecaldo Cantonal Forest Nursery in Ticino, Switzerland. Species differed significantly in terms of the ppb.h exposures needed to cause visible symptoms. The most to least symptomatic species grown within open-plots in this study rank as Prunus serotina, Salix viminalis, Vibrnum lantana, Rhamnus cathartica, Betula pendula, Rumex obtusifolius, Sambucus racemosa, Morus nigra, Prunus avium, Fraxinus excelsior, Rhamnus frangula, Alnus viridis, Fagus sylvatica and Acer pseudoplatanus. Similar rankings were obtained in the non-filtered chamber plots. The ranking of species sensitivity closely follows AOT values for the occurrence of initial symptoms and symptom progression across the remainder of the exposure season. Species that first showed evidence of foliar injury also demonstrated the most sensitivity throughout the growing season, with symptoms rapidly advancing over ca. 25-30% of the total plant leaf surfaces by the end of the observation period. Conversely, those species that developed symptoms later in the season had far less total injury to plant foliage by the end of the observation period (1.5 to < 5% total leaf area injured). The current European ambient ozone standard may be insufficient to protect native plant species from visible foliar injury, and many more native species may be sensitive to ozone-induced foliar injury than are currently known.
Remifentanil is a potent opioid with a short duration of action. It has the potential for large-dose opioid anesthesia without an obligatory prolonged period of mechanical ventilation. However, ...because of high clearance and rapid tissue distribution, cardiopulmonary bypass (CPB) may influence its pharmacokinetics and alter drug requirements. We administered remifentanil by continuous infusion to 68 patients having coronary artery bypass graft surgery during CPB with hypothermia to describe the effects of these interventions on its pharmacokinetics. Remifentanil concentrations were measured before, during, and after CPB. Disposition was best described by a two-compartment model. The volume of distribution increased by 86% with institution of CPB and remained increased after CPB. Elimination clearance decreased by 6.37% for each degree Celsius decrease from 37 degrees C.
Remifentanil concentrations decrease with the institution of cardiopulmonary bypass because of an increase in the volume of distribution. The decrease in elimination clearance with hypothermia results in increased total remifentanil concentrations during cardiopulmonary bypass if the infusion rate is not altered. More constant blood remifentanil levels may be obtained by reducing remifentanil infusion rate by 30% for each 5 degrees C decrease in temperature.
To investigate clinically important hypotension and bradycardia after induction of anesthesia with propofol, we analyzed data from a Phase IV stepwise study involving 25,981 patients, 1722 ...institutions, and 1819 anesthesiologists. In Step 1, propofol was used for induction only. In Step 2, propofol was used for induction and then maintenance by intermittent injection. In Step 3, an induction dose was followed by a maintenance infusion. Participants were to be 18-80 yr of age and ASA physical status I-III; they could not have a continuing pregnancy or prior adverse anesthetic experience. Detailed data on demographic, perioperative, and outcome variables were recorded on data collection forms. The overall incidence of hypotension (systolic blood pressure < 90 mm Hg) was 15.7%; 77% of the episodes were recorded within 10 min of induction of anesthesia with propofol. Bradycardia (heart rate < 50 beats/min) occurred in 4.8% of patients, with 42% of the episodes in the first 10 min. Only 1.3% of patients had both hypotension and bradycardia. The incidence of hypotension was significantly higher for the elderly, females, Caucasians, those undergoing abdominal and integumentary procedures, and those given propofol with opioids, benzodiazepines, or propranolol. Bradycardia was significantly more common when propofol was combined with opioids or chronically taken beta-adrenergic receptor-blocking drugs. Bradycardia and hypotension were not commonly associated. Giving this new drug by protocol, even inexperienced anesthesiologists incurred few adverse hemodynamic changes. Hemodynamic changes were transient and rarely (< 0.2%) required drug therapy. Cardiovascular changes and drug interactions were predictable and manageable based on knowledge of the pharmacology of propofol.
The pharmacokinetics of remifentanil Michelsen, Luis G.; Hug, Carl C.
Journal of clinical anesthesia,
12/1996, Letnik:
8, Številka:
8
Journal Article
Recenzirano
Opioids decrease the sympathetic and somatic responses to noxious stimulation and can be given in high doses without negative inotropic effects, even in patients with impaired cardiac function. With ...currently available opioids, precise titration of dose to effect is difficult, and high doses result in drug accumulation and prolonged respiratory depression. Remifentanil is a new synthetic opioid with direct action on μ-opioid receptors. It has a rapid onset and short latency to peak effect. It is rapidly inactivated by esterases in both blood and tissues, resulting in a very short duration of action. The context-sensitive half-life remains very short (3 to 4 minutes), independent of the duration of infusion. These characteristics facilitate titration of dose to effect and also allow the use of very high doses (ED
99) without prolonging recovery from its effects. The duration of action of remifentanil has been found to be short, even in patients with renal or hepatic failure, although only low doses have been used in the studies published to date. The hydrolysis of remifentanil produces a metabolite with very weak opioid receptor activity that does not contribute to the effects of remifentanil.Possible disadvantages of the drug include (1) the need to mix the lyophilized drug with a diluent, (2) administration as a continuous infusion, (3) risk of rapid loss of analgesic and anesthetic effects if the infusion is interrupted accidentally, and (4) difficulty in judging the dose of another, longer lasting opioid that will be required to control postoperative pain without producing excessive ventilatory depression. Remifentanil is likely to be more expensive than other opioids, but its use may reduce overall costs if prompt recovery from its effects results in shorter stays in the operating room and recovery units.
Acrp30/adiponectin is reduced in the serum of obese and diabetic individuals, and the genetic locus of adiponectin is linked to the metabolic syndrome. Recombinant adiponectin, administered to ...diet-induced obese mice, induced weight loss and improved insulin sensitivity. In muscle and liver, adiponectin stimulates AMP-activated protein kinase activation and fatty acid oxidation. To expression-clone molecules capable of binding adiponectin, we transduced a C2C12 myoblast cDNA retroviral expression library into Ba/F3 cells and panned infected cells on recombinant adiponectin linked to magnetic beads. We identified T-cadherin as a receptor for the hexameric and high-molecular-weight species of adiponectin but not for the trimeric or globular species. Only eukaryotically expressed adiponectin bound to T-cadherin, implying that post-translational modifications of adiponectin are critical for binding. An adiponectin mutant lacking a conserved N-terminal cysteine residue required for formation of hexamer and high-molecular-weight species did not bind T-cadherin in coimmunoprecipitation studies. Although lacking known cellular functions, T-cadherin is expressed in endothelial and smooth muscle cells, where it is positioned to interact with adiponectin. Because T-cadherin is a glycosylphosphatidylinositol-anchored extracellular protein, it may act as a coreceptor for an as-yet-unidentified signaling receptor through which adiponectin transmits metabolic signals.
Visfatin: A new adipokine Hug, C; Lodish, H.F
Science,
01/2005, Letnik:
307, Številka:
5708
Journal Article
Recenzirano
Odprti dostop
Hug and Lodish takes a look at new member of the adipokine family, visfatin. Like insulin, visfatin stimulates glucose uptake by cultured adipocytes and muscle cells and suppresses glucose release by ...cultured hepatocyes. Visfatin, like insulin, also induces phosphorylation of signal transduction proteins that operate downstream of the insulin receptor.
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