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Mars
Terms modified by Mars Selected AbstractsPredicting species distributions from museum and herbarium records using multiresponse models fitted with multivariate adaptive regression splinesDIVERSITY AND DISTRIBUTIONS, Issue 3 2007Jane Elith ABSTRACT Current circumstances , that the majority of species distribution records exist as presence-only data (e.g. from museums and herbaria), and that there is an established need for predictions of species distributions , mean that scientists and conservation managers seek to develop robust methods for using these data. Such methods must, in particular, accommodate the difficulties caused by lack of reliable information about sites where species are absent. Here we test two approaches for overcoming these difficulties, analysing a range of data sets using the technique of multivariate adaptive regression splines (MARS). MARS is closely related to regression techniques such as generalized additive models (GAMs) that are commonly and successfully used in modelling species distributions, but has particular advantages in its analytical speed and the ease of transfer of analysis results to other computational environments such as a Geographic Information System. MARS also has the advantage that it can model multiple responses, meaning that it can combine information from a set of species to determine the dominant environmental drivers of variation in species composition. We use data from 226 species from six regions of the world, and demonstrate the use of MARS for distribution modelling using presence-only data. We test whether (1) the type of data used to represent absence or background and (2) the signal from multiple species affect predictive performance, by evaluating predictions at completely independent sites where genuine presence,absence data were recorded. Models developed with absences inferred from the total set of presence-only sites for a biological group, and using simultaneous analysis of multiple species to inform the choice of predictor variables, performed better than models in which species were analysed singly, or in which pseudo-absences were drawn randomly from the study area. The methods are fast, relatively simple to understand, and useful for situations where data are limited. A tutorial is included. [source] Acute renal failure in patients with cirrhosis: Perspectives in the age of MELDHEPATOLOGY, Issue 2 2003Richard Moreau In patients with cirrhosis, acute renal failure is mainly due to prerenal failure (caused by renal hypoperfusion) and tubular necrosis. The main causes of prerenal failure are "true hypovolemia" (induced by hemorrhage or gastrointestinal or renal fluid losses), sepsis, or type 1 hepatorenal syndrome (HRS). The frequency of prerenal failure due to the administration of nonsteroidal anti-inflammatory drugs or intravascular radiocontrast agents is unknown. Prerenal failure is rapidly reversible after restoration of renal blood flow. Treatment is directed to the cause of hypoperfusion, and fluid replacement is used to treat most cases of "non-HRS" prerenal failure. In patients with type 1 HRS with very low short-term survival rate, liver transplantation is the ideal treatment. Systemic vasoconstrictor therapy (with terlipressin, noradrenaline, or midodrine [combined with octreotide]) may improve renal function in patients with type 1 HRS waiting for liver transplantation. MARS (for molecular adsorbent recirculating system) and the transjugular intrahepatic portosystemic shunt may also improve renal function in these patients. In patients with cirrhosis, acute tubular necrosis is mainly due to an ischemic insult to the renal tubules. The most common condition leading to ischemic acute tubular necrosis is severe and sustained prerenal failure. Little is known about the natural course and treatment (i.e., renal replacement therapy) of cirrhosis-associated acute tubular necrosis. [source] Long-term changes in ozone mini-hole event frequency over the Northern Hemisphere derived from ground-based measurementsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2002Janusz W. Krzy Abstract Decadal changes of ozone mini-hole event appearance over the Northern Hemisphere midlatitudes are examined based on daily total ozone data from seven stations having long records (four decades or more) of ozone observations. The various threshold methods for accepting and rejecting the ozone minima as mini-holes are examined. Mini-hole event activity is seen to be rather stable when averaged over a decadal time scale if the mini-holes are selected as large negative departures (exceeding 20%) relative to the moving long-term total ozone reference. The results are compared with a previous ozone mini-hole climatology derived from satellite data (TOMS measurements on board the Nimbus-7 satellite for the period 1978,93). A nonlinear statistical model (MARS), which takes into account various total ozone dynamical proxies (from NCEP,NCAR reanalysis), is used to study dynamical factors responsible for the ozone extremes over Arosa in the period 1950,99. The model explains as much as 95% of the total variance of the ozone extremes. The model,observation differences averaged over the decadal intervals are rather smooth throughout the whole period analysed. It is suggested that the short-term dynamical processes controlling the appearance of ozone extremes influenced the ozone field in a similar way before and after the onset of abrupt ozone depletion in the early 1980s. The analysis of the ozone profile and the tropopause pressure (from the ozonesondings over Hohenpeissenberg, 1966,99) during mini-hole events shows ,60% ozone reduction in the lower stratosphere and an approximately 50 hPa upward shift of the thermal tropopause there. Copyright © 2002 Royal Meteorological Society. [source] Symptom Perception and Adherence to Asthma Controller MedicationsJOURNAL OF NURSING SCHOLARSHIP, Issue 3 2006Ruth Ohm Purpose: To explore asthma symptom perception and the relationship between asthma symptom perception and adherence to asthma treatment. Design: Adult patients (N=120) of asthma/allergy specialty clinics, taking Advair® as a controller medication, were enrolled in this cross-sectional descriptive study. Methods: Ninety-seven participants completed 4 weeks of daily diaries to assess subjective symptom perception and measured peak expiratory flow rates (PEFR), both done twice daily. Individual perceptual accuracy scores (PAS) were determined by correlating the subjective symptom perception scores with the PEFRs. Measures included demographic variables, illness identity (personal control and treatment control, consequences, and timeline-cyclical subscales of the IPQ-R), asthma severity (FEV1 percentage) and a single-item indicator of perceived asthma severity. Adherence was measured by the Medication Adherence Report Scale (MARS) and by an Advair® dose count (percentage of doses taken as prescribed). Findings: Independent t tests comparing adherence rates of good versus poor perceivers were not significant, using either the percentage Advair® dose count or the MARS. Multiple regression analyses showed that years with asthma, illness identity, and peak flow variability were all significant explanatory variables for perceptual accuracy. Conclusion: Peak flow variability adds complexity to the relationship between perceptual accuracy and adherence that warrants further investigation. [source] Nonlinear modelling of periodic threshold autoregressions using TsmarsJOURNAL OF TIME SERIES ANALYSIS, Issue 4 2002PETER A. W. LEWIS We present new methods for modelling nonlinear threshold-type autoregressive behaviour in periodically correlated time series. The methods are illustrated using a series of average monthly flows of the Fraser River in British Columbia. Commonly used nonlinearity tests of the river flow data in each month indicate nonlinear behaviour in certain months. The periodic nonlinear correlation structure is modelled nonparametrically using TSMARS, a time series version of Friedman's extended multivariate adaptive regression splines (MARS) algorithm, which allows for categorical predictor variables. We discuss two methods of using the computational algorithm in TSMARS for modelling and fitting periodically correlated data. The first method applies the algorithm to data from each period separately. The second method models data from all periods simultaneously by incorporating an additional predictor variable to distinguish different behaviour in different periods, and allows for coalescing of data from periods with similar behaviour. The models obtained using TSMARS provide better short-term forecasts for the Fraser River data than a corresponding linear periodic AR model. [source] Acute systemic, splanchnic and renal haemodynamic changes induced by molecular adsorbent recirculating system (MARS) treatment in patients with end-stage cirrhosisALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2007G. DONATI Summary Aim To evaluate the acute effect of treatment with the molecular adsorbent recirculating system (MARS) on splanchnic, renal and systemic haemodynamics in patients with end-stage cirrhosis. Methods Twelve patients with end-stage cirrhosis, undergoing MARS treatment, were enrolled. The following haemodynamic parameters were measured by means of Doppler ultrasonography and thoracic electrical bioimpedance, before and after each session: portal velocity, renal and splenic resistance indices, cardiac output, cardiac stroke volume, heart rate, mean arterial pressure, systemic vascular resistance. Results Median portal velocity increased significantly after treatment (23.7 vs. 20.3 cm/s, P < 0.05) while renal resistance index (0.72 vs. 0.75, P < 0.05) and splenic resistance index (0.60 vs. 0.65, P < 0.05) decreased significantly. Mean arterial pressure (83 vs. 81 mmHg, P < 0.05) and vascular resistance (899 vs. 749 dyne. s/cm5, P < 0.05) increased significantly, while cardiac output and stroke volume showed no significant changes. Conclusions Data emerging from this investigation suggest that MARS treatment improves significantly various haemodynamic alterations in cirrhotic patients in the short term. The observed decrease in renal vascular resistance and improvement in splenic resistance index, a parameter related to portal resistance, which leads us to hypothesize that these haemodynamic effects are probably mediated by clearance of vasoactive substances during MARS treatment. [source] MARS®: a futile tool in centres without active liver transplant supportLIVER INTERNATIONAL, Issue 1 2007Chun-Tao Wai Abstract Background and aim: Studies on Molecular Adsorbent Recycling Systems (MARS®) showed inconclusive survival benefits. Patients and method: We evaluated the efficacy of MARS® for patients with either acute liver failure (ALF) or acute-on-chronic liver failure (AoCLF) at our centre, from February 2002 till April 2006 retrospectively. Results: Fifty ALF patients underwent median (range) three (1,10) sessions of MARS®. Acute exacerbations of chronic hepatitis B (n=26) and drug-induced liver injury (n=12) were the commonest causes. Living donors were available in 6, 2 paediatric patients underwent left lobe and four adults underwent right lobe living donor liver transplant. Among the 44 ALF patients without a suitable living donor, one underwent deceased donor liver transplant and survived, another 19-year-old male with acute exacerbations of chronic hepatitis B recovered without transplant, and the rest died. Twenty-six had AoCLF and underwent four (1,10) MARS® sessions. Sepsis (n=16) and upper gastrointestinal bleeding (n=4) were the commonest precipitating factors. None had a suitable living or deceased donor, suitable for transplantation during their hospitalization. Only one of 26 AoCLF patients survived the hospitalization, but the survivor died of sepsis 1 month later. Conclusion: In this non-randomized study, survival after MARS® was related to the availability of transplant, and in patients where living or deceased donor transplant was unavailable, MARS® was of little benefit. Randomized-controlled trials on MARS® are urgently needed to clarify its clinical utility. [source] Molecular adsorbent recirculating system treatment for patients with liver failure: the Hong Kong experienceLIVER INTERNATIONAL, Issue 6 2006Alexander Chiu Abstract: Background: The molecular adsorbent recirculating system (MARS) is an extracorporeal liver dialysis system that allows selective removal of bilirubin and other albumin-bound toxins. We reported here our experience with the use of this technique for management of liver failure at Queen Mary Hospital, Hong Kong. Methods: From December 2002 to 2004, a total of 74 MARS sessions were performed on 22 patients. The cause of liver failure included acute liver failure (n=2), acute on chronic liver failure (n=12), posthepatectomy liver failure (n=4), and posttransplantation allograft failure (n=4). Results: MARS treatment showed significant reduction in total bilirubin level, serum ammonia level and blood urea, and nitrogen (P<0.001 for all three parameters). Five patients (22.7%) were able to bridge to transplantation and one patient (4.5%) made a spontaneous recovery. The 30-day mortality rate was 72.7%. Conclusions: Our results indicated that MARS can effectively improve serum biochemistry and is suitable for temporarily supporting patients with liver failure where transplantation is not immediately available. There is, however, no clear evidence showing that MARS can increase survival, improve the chance of transplantation or assist liver regeneration. Future studies in the form of randomized-controlled trials are crucial to characterize the true potential of this treatment. [source] MARS preconditioning for living donor liver transplantation: panacea or placebo?LIVER INTERNATIONAL, Issue 4 2005R. S. Brown Jr. [source] Role of circulating neurotoxins in the pathogenesis of hepatic encephalopathy: potential for improvement following their removal by liver assist devicesLIVER INTERNATIONAL, Issue 2003Roger F. Butterworth Abstract Both acute and chronic liver failure result in impaired cerebral function known as hepatic encephalopathy (HE). Evidence suggests that HE is the consequence of the accumulation in brain of neurotoxic and/or neuroactive substance including ammonia, manganese, aromatic amino acids, mercaptans, phenols, short-chain fatty acids, bilirubin and a variety of neuroactive medications prescribed as sedatives to patients with liver failure. Brain ammonia concentrations may attain levels in excess of 2 mm, concentrations which are known to adversely affect both excitatory and inhibitory neurotransmission as well as brain energy metabolism. Manganese exerts toxic effects on dopaminergic neurones. Prevention and treatment of HE continues to rely heavily on the reduction of circulating ammonia either by reduction of gut production using lactulose or antibiotics or by increasing its metabolism using l -ornithine- l -aspartate. No specific therapies have so far been designed to reduce circulating concentrations of other toxins. Liver assist devices offer a potential new approach to the reduction of circulating neurotoxins generated in liver failure. In this regard, the Molecular Absorbents Recirculating System (MARS) appears to offer distinct advantages over hepatocyte-based systems. [source] Albumin dialysis in cirrhosis with superimposed acute liver injury: possible impact of albumin dialysis on hospitalization costsLIVER INTERNATIONAL, Issue 2003T. Hassanein Abstract Albumin dialysis using the Molecular Adsorbents Recirculating System (MARS) has been found to be beneficial in the treatment of cirrhotic patients with acute decompensation to improve survival as well as reduce associated complications. The present study attempts to analyze the costs involved, and compare it to the benefit as a result of the MARS therapy, thus evaluating its cost-effectiveness. Using the results of a study by Kim et al. (Hepatology 2001) describing the effects of complications on the cost of hospitalization in alcoholic liver disease patients, the expenditure incurred in a group of 11 patients treated with standard medical therapy (five survivors) and a group of 12 patients treated with MARS in addition (11 survivors) (Heemann et al., Hepatology 2002) were analyzed. MARS resulted in a reduction of in-hospital deaths, as well as liver disease-related complications. Both these factors led to a substantial reduction of costs in the MARS group, which was enough to counterbalance the extra costs associated with extra-corporeal therapy. In the control group, the total hospitalization cost per survivor were calculated to be at $35 904. In the MARS group, the overall expenditure per survivor including standard medical therapy plus additional MARS liver support therapy were $32 036 , a saving of nearly $4000 compared to the control group. Therefore, it appears that the benefits of MARS therapy are enough to justify the cost of treatment and safe hospital costs, at least in the described population. However, further studies are needed to confirm these results. [source] Economic evaluation and 1-year survival analysis of MARS in patients with alcoholic liver diseaseLIVER INTERNATIONAL, Issue 2003Franz P. Hessel Abstract Objective of this study was to determine 1-year survival, costs and cost-effectiveness of the artificial liver support system Molecular Adsorbent Recirculating System (MARS) in patients with acute-on-chronic liver failure (ACLF) and an underlying alcoholic liver disease. In a case,control study, 13 patients treated with MARS were compared to 23 controls of similar age, sex and severity of disease. Inpatient hospital costs data were extracted from patients' files and hospital's internal costing. Patients and treating GPs were contacted, thus determining resource use and survival 1-year after treatment. Mean 1-year survival time in MARS group was 261 days and 148 days in controls. Kaplan,Meier analysis shows advantages of MARS patients (Logrank: P = 0.057). Direct medical costs per patient for initial hospital stay and 1-year follow-up from a payer's perspective were ,18 792 for MARS patients and ,9638 for controls. The costs per life-year gained are ,29 719 (time horizon 1 year). From a societal perspective, the numbers are higher (costs per life-year gained: ,79 075), mainly because of the fact that there is no regular reimbursement of MARS and therefore intervention costs were not calculated from payer's perspective. A trade-off between medical benefit and higher costs has to be made, but 1-year results suggest an acceptable cost-effectiveness of MARS. Prolonging the time horizon and including indirect costs, which will be done in future research, would probably improve cost-effectiveness. [source] Application of Molecular Adsorbent Recirculating System® in patients with severe liver failure after hepatic resection or transplantation: initial single-centre experiencesLIVER INTERNATIONAL, Issue 2002R Kellersmann Abstract: Acute liver failure after hepatic surgery is still plaqued with high mortality rate. Recently, a liver dialysis system (MARS®) that allows detoxification of albumin-bound substances and may hereby support liver regeneration and patient's recovery has been developed. In the present study, we report our experiences with MARS® dialysis in patients with liver failure after hepatic resection or transplantation. Between September 1999 and January 2001, five patients were treated with MARS® (2,5 courses). Though beneficial effects such as improvement of encephalopathy and renal function as well as reduced bilirubin levels were recorded during MARS® therapy, only one patient survived. Neither significant technical problems nor adverse effects occurred by using MARS® dialysis. We conclude that in surgical patients, acute liver failure is usually part of a complicated clinical course affecting multipleorgan systems. Thus, it is difficult to determine the specific influence of MARS® on patient's outcome. However, beneficial effects observed in our patients justify its continuous use and may stimulate further evaluation in controlled studies with surgical patients. [source] Use of the molecular adsorbents recirculating system as a treatment for acute decompensated wilson diseaseLIVER TRANSPLANTATION, Issue 10 2008Alexander Chiu Acute decompensated Wilson disease presenting as fulminant liver failure is a life-threatening condition for which liver transplantation is the ultimate treatment. It is listed as a status 1 indication according to the United Network for Organ Sharing classification. A massive amount of copper released during the attack induces hemolytic anemia and acute renal failure. Conventional chelating therapy attempting to remove copper from the patient is not satisfactory because there is inadequate time for these drugs to take action and patients are usually oliguric. The Molecular Adsorbents Recirculating System (MARS) is a form of modified dialysis that removes putative albumin-bound toxins associated with liver failure. It is believed that extracorporeal albumin dialysate absorbs the circulating copper molecules that are trapped in the patient's circulation. We report 2 patients with acute decompensated Wilson disease treated with MARS. In the first case, the patient was started on MARS once conventional treatment failed. A significant amount of copper was removed from her circulatory system, and her condition stabilized afterwards. The treatment gained her extra time, and she was eventually bridged to liver transplantation. In the second case, the patient was started on MARS treatment early in the course of his illness, and his condition soon stabilized after the treatment. He was able to return to his home country for liver transplantation. In both cases, MARS was used as a means of preventing deterioration rather than salvaging devastation. In conclusion, MARS may confer benefits to patients with acute decompensated Wilson disease if it is started early in the course of illness. Liver Transpl 14:1512,1516, 2008. © 2008 AASLD. [source] MARS dialysis in decompensated alcoholic liver disease: A single-center experienceLIVER TRANSPLANTATION, Issue 8 2007Birger Wolff Acute decompensation of chronically stable alcoholic liver disease (ALD) is the most common cause of terminal liver failure in developed countries. Molecular adsorbent recirculation system (MARS) is increasingly used as artificial liver support to facilitate spontaneous organ recovery. However, the experience to date and the evidence to justify this therapeutic strategy in acutely decompensated ALD are still insufficient. We report our clinical experience with MARS in 14 patients with acutely decompensated ALD (6 male subjects; median age [interquartile range], 51 [47-56] years; Child-Pugh score, 12 [10-13]; Acute Physiology and Chronic Health Evaluation (APACHE) II score, 20 [18-24]) and severely impaired liver function whose disease was unresponsive to conventional supportive care. At least 3 sessions were applied in any patient (48 sessions in total). Under MARS treatment, the following levels decreased: bilirubin (544 [489-604] to 242 [178-348] ,mol/L; P < 0.001), creatinine (212 [112-385] to 91 [66-210] ,mol/L; P = 0.002), cholestatic parameter gamma-glutamyl transpeptidase (5.9 [1.8-13.1] to 4.6 [1.8-8.3] ,mol/L) (P < 0.001), blood urea nitrogen (56 [32-91] to 34 [21-68] mmol/L; P = 0.044), and platelet count (176 [85-241] to 84 [31-145] Gpt/L; P = 0.004). In contrast, MARS failed to improve daily urine output (P = 0.846), ammonia levels (P = 0.340), or thromboplastin time (P = 0.775). Only 3 patients survived the hospital stay (mortality 78.6%). Although MARS improved laboratory parameters of hepatic detoxification and renal function in patients with acutely decompensated ALD, the patients' mortality remained unsatisfactorily high. Our experience does not support the indiscriminative use of MARS in acutely decompensated ALD without further controlled studies. Liver Transpl 13:1189,1192, 2007. © 2007 AASLD. [source] Review article: albumin in the treatment of liver diseases,new features of a classical treatmentALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 2002V Arroyo Summary Albumin was introduced initially in the treatment of patients with cirrhosis and ascites to increase serum albumin concentration due to its oncotic effect. Although its administration declined some years later, at present it constitutes an essential treatment in clinical hepatology. Several studies have clearly demonstrated its efficacy in the prevention and treatment of circulatory dysfunction and hepatorenal syndrome in patients with cirrhosis. These effects can be due not only to its properties as a plasma expander but also to its capacity to bind numerous substances such as bile acids, nitric oxide and cytokines. Based on this capacity an albumin dialysis system (MARS) has recently been developed. The usefulness of this system in the management of patients with acute and chronic liver failure is, at present, under evaluation. [source] Cerebral blood flow velocity increases during a single treatment with the molecular adsorbents recirculating system in patients with acute on chronic liver failureLIVER TRANSPLANTATION, Issue 8 2001Lars E. Schmidt The aim of this uncontrolled pilot study is to determine the effect of treatment with the molecular adsorbents recirculating system (MARS) on cerebral perfusion in patients with acute on chronic liver failure (AOCLF). In 8 patients (median age, 44 years; range, 35 to 52 years) admitted with AOCLF, a single 10-hour MARS treatment was performed. Hepatic encephalopathy (HE) was graded according to the Fogarty criteria. Changes in cerebral perfusion were determined by transcranial Doppler as mean flow velocity (Vmean) in the middle cerebral artery. Arterial ammonia and bilirubin levels were monitored as a measure of the capability of the MARS to remove water-soluble and protein-bound toxins. During MARS treatment, HE grade improved in 3 patients and remained unchanged in 5 patients (P = .11). Vmean increased from 42 cm/sec (range, 26 to 59 cm/sec) to 72 cm/sec (range, 52 to 106 cm/sec; P < .05), whereas arterial ammonia level decreased from 88 ,mol/L (range, 45 to 117 ,mol/L) to 71 ,mol/L (range, 26 to 98 ,mol/L; P < .05) and bilirubin level from 537 ,mol/L (range, 324 to 877 ,mol/L) to 351 ,mol/L (range, 228 to 512 ,mol/L; P < .05). In conclusion, cerebral perfusion is increased and levels of ammonia and bilirubin are reduced during MARS treatment in patients with AOCLF. [source] Flexible and Robust Implementations of Multivariate Adaptive Regression Splines Within a Wastewater Treatment Stochastic Dynamic ProgramQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 7 2005Julia C. C. Tsai Abstract This paper presents an automatic and more robust implementation of multivariate adaptive regression splines (MARS) within the orthogonal array (OA)/MARS continuous-state stochastic dynamic programming (SDP) method. MARS is used to estimate the future value functions in each SDP level. The default stopping rule of MARS employs the maximum number of basis functions Mmax, specified by the user. To reduce the computational effort and improve the MARS fit for the wastewater treatment SDP model, two automatic stopping rules, which automatically determine an appropriate value for Mmax, and a robust version of MARS that prefers lower-order terms over higher-order terms are developed. Computational results demonstrate the success of these approaches. Copyright © 2005 John Wiley & Sons, Ltd. [source] Thermodynamic Considerations in Solid Adsorption of Bound Solutes for Patient Support in Liver FailureARTIFICIAL ORGANS, Issue 7 2008John F. Patzer II Abstract:, New detoxification modes of treatment for liver failure that use solid adsorbents to remove toxins bound to albumin in the patient bloodstream are entering clinical evaluations, frequently in head-to-head competition. While generally effective in reducing toxin concentration beyond that obtainable by conventional dialysis procedures, the solid adsorbent processes are largely the result of heuristic development. Understanding the principles and limitations inherent in competitive toxin binding, albumin versus solid adsorbent, will enhance the design process and, possibly, improve detoxification performance. An equilibrium thermodynamic analysis is presented for both the molecular adsorbent recirculating system (MARS) and fractionated plasma separation, adsorption, and dialysis system (Prometheus), two advanced systems with distinctly different operating modes but with similar equilibrium limitations. The Prometheus analysis also applies to two newer approaches: sorbent suspension reactor and microsphere-based detoxification system. Primary results from the thermodynamic analysis are that: (i) the solute,albumin binding constant is of minor importance to equilibrium once it exceeds about 105 L/mol; (ii) the Prometheus approach requires larger solid adsorbent columns than calculated by adsorbent solute capacity alone; and (iii) the albumin-containing recycle stream in the MARS approach is a major reservoir of removed toxin. A survey of published results indicates that MARS is operating under mass transfer control dictated by solute,albumin equilibrium in the recycle stream, and Prometheus is approaching equilibrium limits under current clinical protocols. [source] Molecular Adsorbents Recirculating System Dialysis for Liver Insufficiency and Sepsis Following Right Ventricular Assist Device after Cardiac SurgeryARTIFICIAL ORGANS, Issue 8 2004Otrud Vargas Hein Abstract:, We report a case of right heart failure (RHF) and sepsis with liver insufficiency in a 70-year-old patient after coronary artery bypass graft surgery. Three hours after surgery the patient suddenly developed therapy refractory cardiac arrest caused by RHF. He had to have emergency surgery, under which the graft to the right coronary artery was revised and a right ventricular assist device was implanted. Heart function recovered and the assist device was explanted on day 1 after surgery. Thoracic closure was performed on day 5 after surgery. The patient went into septic shock on day 11. Liver dysfunction developed postoperatively and worsened the course of sepsis. Therefore, MARS (molecular adsorbents recirculating system) dialysis was performed once on day 20 after surgery. Liver function improved after MARS therapy and the patient recovered from sepsis. On day 46 the patient was transferred from the ICU of another hospital to one of the peripheral wards, to be finally discharged on day 67. [source] Clinical Experience with Molecular Adsorbent Recirculating System (MARS) in Patients with Drug-induced Liver FailureARTIFICIAL ORGANS, Issue 5 2004Xin-min Zhou Abstract:, The molecular adsorbent recirculating system (MARS) is a novel extracorporeal technique for liver support. We report the clinical results in a group of fourteen patients with drug-induced liver failure. Fourteen patients, aged 22,83 years, with acute or subacute liver failure [mean Child,Turcotte,Pugh (CTP) score 11 (range 8,15)] due to the intake of various drugs (diet pill overdose,2; Chinese traditional medicine (CTM),4; antibiotic, paracetamol, tuberculostatic, or vasodilator abuse,8) were treated with one to seven sessions of MARS. Beneficial effects such as the improvement of encephalopathy and prothrombin activity, as well as a reduction of bilirubin and ammonia were recorded during MARS treatments. Thirteen out of fourteen patients survived the hospitalization (93%), and two of the discharged patients died during the follow-up of 6,12 months. The overall survival rate was about 79%. MARS therapy can contribute to the improved treatment of drug-induced liver failure patients. [source] Indocyanine green elimination but not bilirubin indicates improvement of graft function during MARS therapyCLINICAL TRANSPLANTATION, Issue 6 2007Stefan Scheingraber Abstract:, Measurement of indocyanine green plasma disappearance rate (PDRICG) has been suggested as a meaningful liver function parameter. However, there are only very limited data concerning its value in the monitoring of graft dysfunction (GDF) and primary non-function (PNF) especially during molecular absorbent recirculating system (MARS) therapy. This study was therefore performed to evaluate the diagnostic accuracy to detect and monitor GDF with the measurement of the PDRICG in direct comparison with conventional markers like bilirubin and prothrombin time (PT). Of the 19 liver recipients, four patients with GDF and two patients with PNF were treated with 38 MARS cycles. Only PDRICG did reliably indicate liver function between patients with GDF/PNF and patients with sufficient graft function who served as controls. Moreover, receiver operating characteristic analysis showed the highest areas under the curve (AUC) for PDRICG (AUCPDRICG max: 0.840, AUCPDRICG max: 0.822), followed by bilirubin (AUCbilirubin: 0.528) and PT (AUCPT: 0.546). In contrast to the decrease of the serum bilirubin concentration due to MARS, a noticeable improvement of PDRICG was evident only in patients with GDF. Patients with acute fulminant failure and PNF had significantly lower PDRICG values, which did not improve even during continuous MARS treatments. Conclusively, monitoring of PDRICG is superior to bilirubin and PT measurements to determine the graft function especially in patients with PNF and GDF undergoing MARS therapy. [source] Functional potential of P2P-R: A role in the cell cycle and cell differentiation related to its interactions with proteins that bind to matrix associated regions of DNA?JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2003Robert E. Scott Abstract P2P-R is the alternately spliced product of the P2P-R/PACT gene in that P2P-R lacks one exon encoding 34 amino acids. The 250 kDa P2P-R protein is the predominate product expressed in multiple murine cell lines. It is a highly basic protein that contains multiple domains including an N-terminal RING type zinc finger, a proline rich domain, an RS region, and a C-terminal lysine-rich domain. P2P-R binds the p53 and the Rb1 tumor suppressors and is phosphorylated by the cdc2 and SRPK1a protein kinases. P2P-R also interacts with scaffold attachment factor-B (SAF-B), a well characterized MARs (for matrix attachment regions) binding factor, and may interact with nucleolin, another MARs binding factor. In addition, P2P-R binds single strand DNA (ssDNA). The expression of P2P-R is regulated by differentiation and cell cycle events. P2P-R mRNA is markedly repressed during differentiation, whereas immunoreactive P2P-R protein levels are >10-fold higher in mitotic than in G0 cells. The localization of P2P-R also is modulated during the cell cycle. During interphase, P2P-R is present primarily in nucleoli and nuclear speckles whereas during mitosis, P2P-R associates with the periphery of chromosomes. Overexpression of near full length P2P-R induces mitotic arrest in prometaphase and mitotic apoptosis, and overexpression of selected P2P-R segments also can promote apoptosis. This compendium of data supports the possibility that P2P-R may form complexes with the Rb1 and/or p53 tumor suppressors and MARs-related factors, in a cell cycle and cell differentiation-dependent manner, to influence gene transcription/expression and nuclear organization. J. Cell. Biochem. 90: 6,12, 2003. © 2003 Wiley-Liss, Inc. [source] Increasing transient expression of CAT gene in Porphyra haitanensis by Matrix attachment regions and 18S rDNA targeted homologous recombinationAQUACULTURE RESEARCH, Issue 7 2007Zhenghong Zuo Abstract To test whether matrix attachment regions (MARs) and 18S rDNA can influence CAT gene transient expression positively in the red algae Porphyra haitanensis, a targeting vector pHR-CAT containing a portion of the 18S rDNA from P. haitanensis, pMAR1-HR-CAT containing one MAR from silkworm and a portion of the 18S rDNA from P. haitanensis and pMAR2-HR-CAT containing two MARs from silkworm and a portion of the 18S rDNA from P. haitanensis were constructed. With the electroporation method, the vectors were transferred into the protoplasts from the thalli of P. haitanensis. The results showed that the expression of chloramphenicol acetyl transferase (CAT) protein in transformed cells reached a maximum at 96 h after transformation. It was increased markedly with the pMAR2-HR-CAT compared with the pHR-CAT or the pCAT@3-control vector (P<0.01), and it was increased inconspicuously with pHR-CAT compared with the pCAT@3-control vector (P>0.05). It is suggested that MAR from silkworm could enhance the transient expression of foreign genes in P. haitanensis. [source] The late Miocene to Pleistocene ice-rafting history of southeast GreenlandBOREAS, Issue 1 2002KRISTEN E. K. ST. JOHN Analysis of a Miocene-Pleistocene ice-rafted debris (IRD) record from the western Irminger Basin provides evidence for the initiation and long-term behavior of the SE portion of the Greenland Ice Sheet. In the late Miocene (,7.3 Ma), IRD supply to Ocean Drilling Program site 918 increased significantly indicating that glaciers large enough to reach sea level were present in SE Greenland long before the onset of widespread Northern Hemisphere glaciation. IRD accumulated at this site throughout the Pliocene and Pleistocene, supporting the hypothesis that SE Greenland was a key nucleation area for the formation of the Greenland Ice Sheet. Since glacial onset, the western Irminger Basin IRD record is characterized by a succession of episodes with high IRD mass accumulation rates (MARs). The site 918 IRD record indicates that greatest iceberg production in SE Greenland occurred during major climatic transitions (e.g. widespread Northern Hemisphere glacial expansion at 2.7 Ma and the mid-Pleistocene climate shift at 0.9 Ma), and that SE Greenland sometimes also led the northern North Atlantic region in glacial response to climatic forcing (e.g. glacial intensification at ,4.8 and, along with NE Greenland, at ,3.5 Ma). [source] Britomart's Armor in Spenser's Faerie Queene: Reopening Cultural Matters of Gender and FigurationENGLISH LITERARY RENAISSANCE, Issue 1 2009Judith H. Anderson In the early cantos of The Faerie Queene, Book III, Britomart is the figure of a young woman vested in armor that forms and masks, expresses and veils, protects and contains her, and she is further invested in finding Artegall, himself a figure vested in various armors. By the beginning of Book IV, Britomart, the armed but nubile virgin, not only Venus-Virgo but also Venus within Mars, has become a complex cultural signifier implicated in cultural conceptions of gender. Her figure indicates that a binaristic conception of gender is inadequate: there are four terms in play or at least two in each of the major amatory players of the books featuring Britomart. Venus-Virgo does not sufficiently represent this doubled perception. Unless seen as a cultural inflection of the composite Venus-Mars, Venus-Virgo conceals the truly Martian, martial, masculine nature of Britomart's figure and elides the hard questions that her armor presents, those involving combinations of nubility and firm resistance, incorporation and active agency, the kinds of questions involving what the early modern period typically perceived as masculinity. My essay explores how a doubled perception of Britomart's gender develops through a process of figuration in allegorical narrative: Britomart is an evolving figure, and her armor conspicuously participates in,figures,the development of her integrity and its loss. [source] A view of extraterrestrial soilsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2009G. Certini Summary The nature of soils on celestial bodies other than Earth is a growing area of research in planetary geology. However, disagreement over the significance of these deposits arises, in part, through the lack of a unified concept and definition of soil in the literature. The pragmatic definition ,medium for plant growth' is taken by some to imply the necessity of biota for soil to exist, and has been commonly adopted in the planetary science community. In contrast, a more complex and informative definition is based on scientific theory: soil is the (bio)geochemically/physically altered material at the surface of a planetary body that encompasses surficial extraterrestrial telluric deposits. This definition is based on the premise that soil is a body that retains information about its environmental history and that it does not need the presence of life to form. Four decades of missions have gathered geochemical information regarding the surface of planets and bodies within the Solar System, and information is quickly increasing. Reviewing the current knowledge on properties of extraterrestrial regoliths, we conclude that the surficial deposits of Venus, Mars and our moon should be considered to be soils in a pedological sense, and that Mercury and some large asteroids are covered in mantles that are soil candidates. A key environmental distinction between Earth and other Solar System bodies is the presence of life, and because of this dissimilarity in soil-forming processes, it is reasonable to distinguish these (presently) abiotic soils as Astrosols. Attempts to provide detailed classifications of extraterrestrial soils are premature, given our poor current knowledge of the Universe, but they highlight the fact that Earth possesses almost-abiotic environments that lend themselves to providing more understanding about telluric bodies of the Solar System. "He found himself in the neighbourhood of the asteroids 325, 326, 327, 328, 329, and 330. He began, therefore, by visiting them, in order to add to his knowledge." (Excerpt from the The Little Prince by Antoine de Saint-Exupéry) [source] Microbial life in glacial ice and implications for a cold origin of lifeFEMS MICROBIOLOGY ECOLOGY, Issue 2 2007P. Buford Price Abstract Application of physical and chemical concepts, complemented by studies of prokaryotes in ice cores and permafrost, has led to the present understanding of how microorganisms can metabolize at subfreezing temperatures on Earth and possibly on Mars and other cold planetary bodies. The habitats for life at subfreezing temperatures benefit from two unusual properties of ice. First, almost all ionic impurities are insoluble in the crystal structure of ice, which leads to a network of micron-diameter veins in which microorganisms may utilize ions for metabolism. Second, ice in contact with mineral surfaces develops a nanometre-thick film of unfrozen water that provides a second habitat that may allow microorganisms to extract energy from redox reactions with ions in the water film or ions in the mineral structure. On the early Earth and on icy planets, prebiotic molecules in veins in ice may have polymerized to RNA and polypeptides by virtue of the low water activity and high rate of encounter with each other in nearly one-dimensional trajectories in the veins. Prebiotic molecules may also have utilized grain surfaces to increase the rate of encounter and to exploit other physicochemical features of the surfaces. [source] Experimental silicification of the extremophilic Archaea Pyrococcus abyssi and Methanocaldococcus jannaschii: applications in the search for evidence of life in early Earth and extraterrestrial rocksGEOBIOLOGY, Issue 4 2009F. ORANGE Hydrothermal activity was common on the early Earth and associated micro-organisms would most likely have included thermophilic to hyperthermophilic species. 3.5,3.3 billion-year-old, hydrothermally influenced rocks contain silicified microbial mats and colonies that must have been bathed in warm to hot hydrothermal emanations. Could they represent thermophilic or hyperthermophilic micro-organisms and if so, how were they preserved? We present the results of an experiment to silicify anaerobic, hyperthermophilic micro-organisms from the Archaea Domain Pyrococcus abyssi and Methanocaldococcus jannaschii, that could have lived on the early Earth. The micro-organisms were placed in a silica-saturated medium for periods up to 1 year. Pyrococcus abyssi cells were fossilized but the M. jannaschii cells lysed naturally after the exponential growth phase, apart from a few cells and cell remains, and were not silicified although their extracellular polymeric substances were. In this first simulated fossilization of archaeal strains, our results suggest that differences between species have a strong influence on the potential for different micro-organisms to be preserved by fossilization and that those found in the fossil record represent probably only a part of the original diversity. Our results have important consequences for biosignatures in hydrothermal or hydrothermally influenced deposits on Earth, as well as on early Mars, as environmental conditions were similar on the young terrestrial planets and traces of early Martian life may have been similarly preserved as silicified microfossils. [source] An optimum design of deep-space downlinks affected by tropospheric attenuation,INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2009Emilio Matricciani Abstract In the paper, we propose an optimum design of deep-space downlinks made with 2 hops, at Ka band and above, in which each hop should be designed for providing half of the total noise-to-signal power ratio. We have derived this result from maximizing the ratio between the tropospheric attenuation in the 2-hop downlink and that in the 1-hop downlink. The design of the 1st hop (free-space) of the 2-hop downlink can reduce the spacecraft power, for the same antennas physical size, by increasing the carrier frequency from Ka band (32,GHz) to W band (80,GHz). This choice is not available in 1-hop downlink design because of the huge Earth tropospheric attenuation expected in the W frequency band. To show a practical design, we have applied the theory to compare 1-hop downlink design at 32,GHz to 2-hop downlink design that adopts 32 or 80,GHz in the 1st hop. The calculations refer to spacecrafts located at two astronomical units (300×106,km, about planet Mars) and to NASA and ESA receiving stations located in Goldstone (California), Cebreros (Madrid, Spain), Canberra and New Norcia (Australia). At 0.1% outage probability, in an average year or in the worst month, 1-hop downlinks show performance critical or close to fail, because of the large tropospheric attenuation (except at Goldstone), while 2-hop downlinks always work. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||