Clinical validation of an evidence-based method to adjust Pancreatic Enzyme Replacement Therapy through a prospective interventional study in paediatric patients with Cystic Fibrosis

Background A method to adjust Pancreatic Enzyme Replacement Therapy in Cystic Fibrosis is not currently available. Objectives To assess the in vivo efficacy of a method to adjust the dose of enzymatic supplement in CF extrapolated from previous in vitro digestion studies (theoretical optimal dose, TOD). Secondly, to assess how individual patient characteristics influence the expected coefficient of fat absorption (CFA) and thus to identify an individual correction factor to improve TOD. Methods A prospective interventional study in 43 paediatric patients with CF from 5 European centres. They followed a 24h fixed diet with the theoretical optimal dose for each meal. Faecal collection was carried out between colorimetric markers in order to include all the faeces corresponding to the fixed diet. Beta regression models were applied to assess the associations of individual patient characteristics with the CFA. Results Median CFA was 90% (84, 94% 1st, 3rd Q.) with no significant differences among centres. Intestinal transit time was positively associated with CFA (p = 0.007), but no statistical associations were found with and age, gender, phenotype or BMI. Regression model showed no improvement of the in vitro predicted theoretical optimal dose when taking individual patient characteristics into account. Conclusion Strict adherence to the theoretical optimal dose of enzymatic supplement for a prescribed meal, led to median CFA levels at the clinical target of 90% with a low variability between patients. The proposed method can be considered as a first approach for an evidencebased method in PERT dosing based on food characteristics. Results have to be confirmed in free dietary settings

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L−1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4°C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature

Photoluminescence imaging of speleothem microbanding with a high-resolution confocal scanning laser macroscope

Micron level resolution is required to image tightly spaced annual bands in speleothems. These same bands must be viewed over several millimeters and sometimes centimeters in order to ensure continuity. We report luminescence imaging results from several speleothem specimens using a novel confocal scanning laser macroscope instrument. The macroscope can non-destructively image specimens as large as 7.5 x 7.5 cm using reflected light and photoluminescence with a 10 μm lateral resolution in under 10 s. A high-resolution version of the macroscope can image specimens up to 1-2 cm in size with lateral resolutions ranging from 1 to 2 μm depending upon the laser scan lens utilized. The combination of both these instruments allows for entire specimens to be imaged even beyond 7.5 x 7.5 cm fields of view via tiling. Confocal imaging improves overall resolution of the instrument by eliminating light originating from outside the focal plane which tends to blur the image. High-contrast, crisp images are achieved in this way. We show photoluminescence imaging results for speleothem specimens where emphasis is placed on resolving to the level of annual bands. (C) 2000 Published by Elsevier Science Ltd and INQUA. All rights reserved

beta-Ureidopropionase deficiency: an inborn error of pyrimidine degradation associated with neurological abnormalities.

beta-Ureidopropionase deficiency is an inborn error of the pyrimidine degradation pathway, affecting the cleavage of N-carbamyl-beta-alanine and N-carbamyl-beta-aminoisobutyric acid. In this study, we report the elucidation of the genetic basis underlying a beta-ureidopropionase deficiency in four patients presenting with neurological abnormalities and strongly elevated levels of N-carbamyl-beta-alanine and N-carbamyl-beta-aminoisobutyric acid in plasma, cerebrospinal fluid and urine. No beta-ureidopropionase activity could be detected in a liver biopsy obtained from one of the patients, which reflected the complete absence of the beta-ureidopropionase protein. Analysis of the beta-ureidopropionase gene (UPB1) of these patients revealed the presence of two splice-site mutations (IVS1-2A>G and IVS8-1G>A) and one missense mutation (A85E). Heterologous expression of the mutant enzyme in Escherichia coli showed that the A85E mutation resulted in a mutant beta-ureidopropionase enzyme without residual activity. Our results demonstrate that the N-carbamyl-beta-amino aciduria in these patients is due to a deficiency of beta-ureidopropionase, which is caused by mutations in the UPB1 gene. Furthermore, an altered homeostasis of beta-aminoisobutyric acid and/or increased oxidative stress might contribute to some of the clinical abnormalities encountered in patients with a beta-ureidopropionase deficiency. An analysis of the presence of the two splice site mutations and the missense mutation in 95 controls identified one individual who proved to be heterozygous for the IVS8-1G>A mutation. Thus, a beta-ureidopropionase deficiency might not be as rare as is generally considered