Publications by authors named "Jan Havel"

Background: Severe acute pancreatitis is associated with high morbidity and mortality. Melatonin is known as the activator of antioxidant enzymes. The main purpose of this study was to evaluate the clinical effect of melatonin treatment in a pig model with induced acute pancreatitis.

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Objectives: In severe acute pancreatitis, the administration of fluids in the presence of positive fluid responsiveness is associated with better outcome when compared to guiding therapy on central venous pressure. We compared the effects of such consequent maximization of stroke volume index with a regime using individual values of stroke volume index assessed prior to severe acute pancreatitis induction as therapeutic hemodynamic goals.

Design: Prospective, randomized animal study.

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A new ketoreductase useful for asymmetric synthesis of chiral alcohols was identified in the cyanobacterium Synechococcus sp. strain PCC 7942. Mass spectrometry of trypsin-digested peptides identified the protein as 3-ketoacyl-[acyl-carrier-protein] reductase (KR) (EC 1.

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An incubator with up to 16 parallel bubble columns was equipped with artificial light sources assuring a light supply with a homogenous light spectrum directly above the bioreactors. Cylindrical light reflecting tubes were positioned around every single bubble column to avoid light scattering effects and to redirect the light from the top onto the cylindrical outer glass surface of each bubble column. The light reflecting tubes were equipped with light intensity filters to control the total light intensity for every single photo-bioreactor.

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The obligate photoautotrophic cyanobacterium Synechococcus PCC7942 and the photoheterotrophic heterocystous cyanobacterium Noctoc muscorum are able to reduce prochiral ketones asymmetrically to optical pure chiral alcohols without light. An example is the synthesis of S-pentafluoro(phenyl-)ethanol with an enantiomeric excess >99% if 2'-3'-4'-5'-6'-pentafluoroacetophenone is used as substrate. If no light is available for regeneration of the cofactor nicotinamide adenine dinucleotide phosphate (reduced form) (NADPH), glucose is used as cosubstrate.

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A fuzzy-logic light attenuation model was developed and validated for a stirred-tank photobioreactor. Based on this model, local light intensities were used to calculate local specific growth rates of the cyanobacteria Synechococcus PCC 7942. The light regime for maximization of biomass space-time yield in a batch process was estimated using a genetic algorithm taking into account the integral average of the individual growth rates.

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In this work, two different genetic algorithms were applied to improve culture media composition for the autotrophic cyanobacteria Synechococcus PCC 7942. Biomass yield and conversion of the asymmetric reduction of 2', 3', 4', 5', 6'-pentafluoroacetophenone were considered as simultaneous objectives, resulting in a multi-objective optimization problem. Even when similar performances of both algorithms were observed, it could be shown that a novel strength pareto approach was able to achieve remarkable results with a reduced number of experiments (160 instead of 320).

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