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    An evaluation of an enzyme immunoassay method for immunoreactive trypsin in dried blood spots

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    A novel monoclonal antibody based enzyme immunoassay (EIA) method for the measurement of the human cationic trypsinogen (NeoScreen, AGEN Biomedical Ltd., Acacia Ridge, Australia) in dried blood spots for the neonatal screening of cystic fibrosis was evaluated. The calibration standards provided as dried blood spots by AGEN are highly unstable and must be replaced with user prepared materials. Reference values from control individuals were obtained by parametric methods. A preliminary comparison with a polyclonal antibody based RIA method (Trypsik, SORIN Biomedica, Saluggia, Italy) was performed. Regression analysis between the RIA and the EIA methods gave a coefficient of correlation of 0.58 for RIA values < 40 •g/L and of 0.77 for RIA values ≥ 40 •g/L. Average CV of the within-run imprecision for the EIA method was 19.6% and for the RIA method 28.8%. CVs of the between-run imprecision at low, intermediate and high values for the EIA method were 23.7%, 15.8%, 15.6% and for the RIA method 20.6%, 14.4%, 11.2%. The diagnostic accuracy analyzed by a Receiver Operating Characteristics (ROC) curve of the RIA method gave a maximum accuracy of 190.9 while that of a simulated ROC curve for the EIA method was 193.0. We found that the precision and the diagnostic accuracy of the EIA method (AGEN) are equal to or better than those of one of the RIA methods

    High- Versus Low-Lipase Acid-Resistant Enzyme Preparations in Cystic Fibrosis: A Crossover Randomized Clinical Trial

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    High-strength pancreatic enzyme preparations have recently come into widespread use in some countries for treatment of pancreatic insufficiency in cystic fibrosis. However, the therapeutic equivalence of these preparations to the standard acid-resistant microsphere preparations, under the same lipase dosage, has not been demonstrated by appropriate clinical trials; they are also considered responsible for severe colonic stricture. In a randomized crossover study, 20 adolescent or adult cystic fibrosis patients were treated in hospital with both low-lipase (A) and high-lipase (B) enteric-coated microsphere preparations. The fat excretion coefficient, evaluated over two 72-h fat balance periods (measured fat intake, 1.43 to 3 g/kg/day according to age), was the main response variable, secondary variables being stool wet and dry weight, fecal nitrogen output, and energy loss. With both preparations, patients were given a daily dose of 1,500-2,000 lipase BP U/g fat ingested, distributed across four meals. The low-strength preparation was divided into three doses during each meal, while the high-strength preparation was taken as a single dose in the middle of each meal. The considerable variability of results did not provide conclusive evidence of equivalence or significant differences between the two preparations in terms of steatorrhea and other variables. However, mean differences between the two treatments and their 95% confidence intervals showed less satisfactory results with the high-lipase preparation. A high-strength preparation is thought to release relatively less enzyme activity in the small intestine, forcing patients to increase their dosage and possibly creating a dangerous enzyme hyperconcentration in the large intestine. For this reason, the occasional occurrence of colonic stricture should be borne in mind, as must the possible scope for division of dosage during each meal

    : A Novel Analog Model Mimicking Megathrust Seismic Cycles

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    In the last decades, seismotectonic analog models have been developed to better understand many aspects of the seismic cycle. Differently from other lab-quake experiments, seismotectonic models mimic the first order characteristics of the seismic cycle in a scaled fashion. Here we introduce Foamquake: a novel seismotectonic model with a granular frictional interface that as a whole behaves elastoplastically. The model experiences cycles of elastic loading and release via spontaneous nucleation of frictional instabilities at the base of an elastic foam wedge, hereafter called foamquakes. These analog earthquakes show source parameters (i.e., moment-duration and moment-rupture area) scaling as great interplate earthquakes and a coseismic displacement of few tens of meters when scaled to nature. Models with two asperities separated by a barrier can be performed with Foamquake given the 3D nature of the setup. Such model configuration generates sequences of full and partial ruptures with different recurrence intervals as well as rupture cascades. By tuning the normal load acting on individual asperities, Foamquake reproduces superimposed cycles rupture patterns such as those observed along natural megathrusts. The physical properties of asperities and barriers affect model seismic behavior. Asperities with similar properties and low yield strength fail preferentially in a simultaneous manner. The combination of all those characteristics suggests that Foamquake is a valuable tool for investigating megathrust seismicity and seismic processes that depend on the 3D nature of the subduction environment
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