The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform
Min Chen - One of the best experts on this subject based on the ideXlab platform.
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One-pot three-Enzyme Synthesis of UDP-Glc, UDP-Gal, and their derivatives.
Carbohydrate research, 2013Co-Authors: Yang Zou, Mengyang Xue, Wenjun Wang, Li Cai, Leilei Chen, Jun Liu, Peng George Wang, Jie Shen, Min ChenAbstract:A UTP-glucose-1-phosphate uridylyltransferase (SpGalU) and a galactokinase (SpGalK) were cloned from Streptococcus pneumoniae TIGR4 and were successfully used to synthesize UDP-galactose (UDP-Gal), UDP-glucose (UDP-Glc), and their derivatives in an efficient one-pot reaction system. The reaction conditions for the one-pot multi-Enzyme Synthesis were optimized and nine UDP-Glc/Gal derivatives were synthesized. Using this system, six unnatural UDP-Gal derivatives, including UDP-2-deoxy-Galactose and UDP-GalN3 which were not accepted by other approach, can be synthesized efficiently in a one pot fashion. More interestingly, this is the first time it has been reported that UDP-Glc can be synthesized in a simpler one-pot three-Enzyme Synthesis reaction system.
G. Adams - One of the best experts on this subject based on the ideXlab platform.
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Duodenal juice total protein and pancreatic Enzyme Synthesis, turnover, and secretion in patients after acute pancreatitis.
Gut, 1993Co-Authors: J. M. Ogden, Stephen J. O'keefe, J. A. Louw, G. AdamsAbstract:It is controversial whether acute pancreatitis has longterm effects on pancreatic function. Pancreatic Enzyme Synthesis, turnover, and secretion were measured in 10 patients in clinical remission who had had one or more (one to six) attacks of acute alcoholic pancreatitis. The studies were done between two and 29 months after the most recent attack. A control group included five patients with no evidence of pancreatic disease. A four hour primed/continuous intravenous infusion of [14C]L-leucine tracer was given with secretin (2 U/kg/h) and cholecystokinin (0.5 U/kg/h) and secreted duodenal juice aspirated. Amylase and trypsin were extracted from duodenal juice by affinity chromatography, permitting measurement of the rate of isotope incorporation into total protein, amylase, and trypsin. The results showed non-parallel changes in Enzyme Synthesis and turnover with decreases in total Enzyme protein and amylase Synthesis and turnover but preservation of trypsin Synthesis and turnover. The low turnover rates may be ascribed to continuing pancreatic cell malfunction after recovery from acute alcoholic pancreatitis and suggest that the decreased amylase secretion rates are partly a consequence of impaired amylase Synthesis and not simply because of loss of pancreatic tissue.
Yang Zou - One of the best experts on this subject based on the ideXlab platform.
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One-pot three-Enzyme Synthesis of UDP-Glc, UDP-Gal, and their derivatives.
Carbohydrate research, 2013Co-Authors: Yang Zou, Mengyang Xue, Wenjun Wang, Li Cai, Leilei Chen, Jun Liu, Peng George Wang, Jie Shen, Min ChenAbstract:A UTP-glucose-1-phosphate uridylyltransferase (SpGalU) and a galactokinase (SpGalK) were cloned from Streptococcus pneumoniae TIGR4 and were successfully used to synthesize UDP-galactose (UDP-Gal), UDP-glucose (UDP-Glc), and their derivatives in an efficient one-pot reaction system. The reaction conditions for the one-pot multi-Enzyme Synthesis were optimized and nine UDP-Glc/Gal derivatives were synthesized. Using this system, six unnatural UDP-Gal derivatives, including UDP-2-deoxy-Galactose and UDP-GalN3 which were not accepted by other approach, can be synthesized efficiently in a one pot fashion. More interestingly, this is the first time it has been reported that UDP-Glc can be synthesized in a simpler one-pot three-Enzyme Synthesis reaction system.
J. M. Ogden - One of the best experts on this subject based on the ideXlab platform.
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Duodenal juice total protein and pancreatic Enzyme Synthesis, turnover, and secretion in patients after acute pancreatitis.
Gut, 1993Co-Authors: J. M. Ogden, Stephen J. O'keefe, J. A. Louw, G. AdamsAbstract:It is controversial whether acute pancreatitis has longterm effects on pancreatic function. Pancreatic Enzyme Synthesis, turnover, and secretion were measured in 10 patients in clinical remission who had had one or more (one to six) attacks of acute alcoholic pancreatitis. The studies were done between two and 29 months after the most recent attack. A control group included five patients with no evidence of pancreatic disease. A four hour primed/continuous intravenous infusion of [14C]L-leucine tracer was given with secretin (2 U/kg/h) and cholecystokinin (0.5 U/kg/h) and secreted duodenal juice aspirated. Amylase and trypsin were extracted from duodenal juice by affinity chromatography, permitting measurement of the rate of isotope incorporation into total protein, amylase, and trypsin. The results showed non-parallel changes in Enzyme Synthesis and turnover with decreases in total Enzyme protein and amylase Synthesis and turnover but preservation of trypsin Synthesis and turnover. The low turnover rates may be ascribed to continuing pancreatic cell malfunction after recovery from acute alcoholic pancreatitis and suggest that the decreased amylase secretion rates are partly a consequence of impaired amylase Synthesis and not simply because of loss of pancreatic tissue.
S J O'keefe - One of the best experts on this subject based on the ideXlab platform.
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Clinical Studies of Human Pancreatic Enzyme Synthesis.
Yale Journal of Biology and Medicine, 1997Co-Authors: S J O'keefeAbstract:Abstract Very little is known of the effects of diet and disease on panceratic Enzyme syntheis in humans as conventional tests measure the secretory response to secreagogues, such as CCK, and secretion may be unrelated to Synthesis because of the masking effect of a large intracellular pool of stored Enzymes (zymogens). In order to obtain information on Enzyme Synthesis, as well as secretion, we have measured the incorporation characteristics of isotopically labelled amino acids (e.g., 14C or 13C leucine tracer) into amylase and trypsin protein, extracted by affinity chromatography from duodenal secretions during pancreatic stimulation with CCK-8 The results of our studies in healthy volunteers and patients have suggested that (a) it takes between 75 and 101 min for the participation of newly synthesized pancreatic Enzymes in the digestive process, and that zymogen stores are replaced at a rate of between 12 percent and 47 percent per hour in normal healthy subjects, (b) the Synthesis and production rates of trypsin and amylase are parallel in healthy subjects, but can diverge under stressful conditions such as hypersecretory states, post-acute pancreatitis and protein malnutrition, (c) hyperphagia stimulates the Synthesis of Enzymes whilst malnutrition diminishes the Synthesis of trypsin to a greater extent than amylase, (d) intravenous glucose and amino acids exert negative feedback control on the Synthesis and release of amylase and trypsin, and (e) the decreased secretion of pancreatic Enzymes in Type 1 insulin-dependent diabetics is more a consequence of defective Enzyme release from zymogen stores than defective Synthesis. In conclusion, our results indicate that changes in pancreatic Enzyme secretion noted in patients do not always reflect changes in Enzyme Synthesis, and that the production of individual Enzymes may diverge under certain circumstances. Based on the methodology described, it should be possible to develop more sensitive clinical tests of pancreatic function that provide information not only on the abiltiy of the pancreas to secrete Enzymes under certain disease states, but also information on the gland's synthetic activity
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Pancreatic Enzyme Synthesis and turnover in human subjects.
The American journal of physiology, 1994Co-Authors: S J O'keefe, W M Bennet, A R Zinsmeister, M W HaymondAbstract:Animal studies have shown that pancreatic Enzyme secretion is independent of Enzyme Synthesis. To investigate this relationship in humans, we have coinfused 14C-labeled leucine tracer with cholecystokinin octapeptide in nine healthy adults for 4 h and measured the rate of appearance of secreted and newly labeled Enzymes in the duodenum. Enzyme secretion was well maintained throughout, but newly labeled Enzymes only appeared in juice between 75 and 101 min (median time, 86 min), indicating that initial secretion was dependent on the release of zymogen stores and that the median production time for new Enzymes was 86 min. Between 85 and 225 min there was a curvilinear increase in the enrichment of secreted Enzymes with newly synthesized Enzymes, suggesting a median turnover rate of zymogen stores of 29%/h (range 12-47%/h). In conclusion, our results suggest that in healthy humans, postprandial pancreatic Enzyme secretion is maintained by the export of a large stored pool and is not rate limited by Enzyme Synthesis, since it takes approximately 86 min for newly synthesized Enzymes to take part in the digestive process.