Browsing by keyword "Pancreatic Elastase"
Now showing items 1-4 of 4
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Evolution of pancreatic function during the first year in infants with cystic fibrosisOBJECTIVE: To describe pancreatic function during the first year of life in infants diagnosed with cystic fibrosis (CF) using serial fecal elastase measurements. STUDY DESIGN: This was a longitudinal study of 82 infants diagnosed with CF through newborn screening. Monthly stool samples were sent to a central laboratory for fecal elastase measurements. RESULTS: A total of 61 infants had an initial stool sample obtained at age 9 months. Twenty-six of 29 infants with a fecal elastase value /g at study entry had a fecal elastase value /g (the accepted cutoff value for pancreatic insufficiency) on all measurements during the year; all 29 had a value /g at the end of the study. Of the 48 infants with initial fecal elastase value /g, 13 had at least 1 fecal elastase value >200 mug/g but had a final stool fecal elastase value /g; however, 4 infants with an initial fecal elastase value /g ended the year with a value >200 mug/g. Eleven of 13 infants with an initial fecal elastase value of >200 mug/g still had a value >200 mug/g at the end of the first year. CONCLUSION: Infants with CF exhibit variability in fecal elastase values during the first year. Infants with a fecal elastase level of 50-200 mug/g at diagnosis should be treated with pancreatic enzyme replacement therapy, but fecal elastase should be remeasured at age 1 year to ensure that those with a falsely low value do not continue to receive pancreatic enzyme replacement therapy unnecessarily. Those with a fecal elastase value >200 mug/g initially can become pancreatic insufficient with time.
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Multiple sites of phosphorylation within the alpha heavy chain of Chlamydomonas outer arm dyneinWe have examined the phosphorylation of the alpha dynein heavy chain (DHC) from the outer arm of the Chlamydomonas flagellum. Quantitative analysis indicates that this DHC is phosphorylated at a minimum of six sites. Using previously identified proteolytic and photocleavage sites (King, S. M., and Witman, G. B. (1988) J. Biol. Chem. 263, 9244-9255), we have mapped two regions that are phosphorylated in vivo. One is located in a 20-kDa section immediately N-terminal to the site of V1 photocleavage. Thus, this region is close to the ATP hydrolytic site and also to the predicted junction between the head and stem domains of the particle. The second encompasses the 90-kDa C-terminal region of the molecule. In this latter section, at least one site is found in an approximately 2-kDa region close to domains that are predicted to adopt a coiled-coil structure in those DHCs that have been sequenced. The alpha DHC also is specifically labeled by endogenous kinases in demembranated, washed axonemes, suggesting that at least one alpha DHC kinase is located close to, or is a component of, the outer arm in situ.
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The platelet surface expression of glycoprotein V is regulated by two independent mechanisms: proteolysis and a reversible cytoskeletal-mediated redistribution to the surface-connected canalicular systemIn this study, we show that the platelet surface expression of glycoprotein (GP) V is regulated by two independent mechanisms. While confirming that both thrombin and neutrophil elastase proteolyse GPV, we show that neutrophil cathepsin G, thrombin receptor activating peptide (TRAP), and a combination of ADP and epinephrine can each result in a decrease in the platelet surface expression of GPV by a nonproteolytic mechanism: a cytoskeletal-mediated redistribution of platelet surface GPV to the surface-connected canalicular system (SCCS). Four independent lines of evidence documented the nonproteolytic nature of this decrease in the platelet surface expression of GPV. First, flow cytometric studies showed that cathepsin G, TRAP, and ADP/epinephrine decreased the platelet surface expression of GPV without changing the total platelet content of GPV. Second, immunoelectron microscopy directly demonstrated translocation of GPV from the platelet surface to the SCCS. Third, the cathepsin G-, TRAP-, and ADP/epinephrine-induced decreases in platelet surface GPV were fully reversible. Fourth, cytochalasin B, an inhibitor of actin polymerization, completely inhibited the cathepsin G-, TRAP-, and ADP/epinephrine-induced decreases in platelet surface GPV. The cytoskeletal-mediated redistribution of GPV occurred in a whole blood milieu and at physiologic temperatures (37 degrees C) and extracellular calcium concentrations (2 mmol/L). This study also defines the diverse effects on GPV, GPIb, and GPIX of multiple important platelet agonists. Cathepsin G proteolysed platelet surface GPIb alpha, but redistributed platelet surface GPIX and GPV to the SCCS. Thrombin proteolysed platelet surface GPV, but redistributed platelet surface GPIb and GPIX to the SCCS. Both TRAP and ADP/epinephrine redistributed platelet surface GPIb, GPIX, and GPV to the SCCS. Elastase proteolysed platelet surface GPIb alpha and GPV, but, unlike the other agonists tested, neither proteolysed nor redistributed platelet surface GPIX. The experiments with TRAP showed that activation of the seven-transmembrane domain thrombin receptor can result in translocation of GPIb, GPIX, and GPV to the SCCS independently of the GPIb-mediated pathway of thrombin-induced platelet activation. This study also provides two additional lines of support for the recent report that GPV is noncovalently complexed with GPIb and GPIX in the platelet surface membrane. First, although only the GPIb alpha subunit of this putative complex is known to be directly linked to the platelet cytoskeleton via actin-binding protein, cytochalasin B inhibited the ADP/epinephrine-, cathepsin G-, and TRAP-induced decrease in platelet surface GPV. Second, triple labeling flow cytometric experiments showed that, on each individual platelet, the ADP/epinephrine-induced decrease and subsequent return of the platelet surface expression of GPV occurred simultaneously with the decrease and subsequent return of the platelet surface expression of GPIb. In summary, the platelet surface expression of GPV is regulated by two independent mechanisms: proteolysis and a reversible, cytoskeletal-mediated redistribution to the SCCS.
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Trp53 deletion stimulates the formation of metastatic pancreatic tumorsThe presence of distant metastases is a common finding on diagnosis of pancreatic cancer; however, the mechanisms underlying the dissemination of this tumor type remain poorly understood. Loss of the p53 tumor suppressor protein has been associated with tumor progression and metastasis in several tumor types including pancreatic ductal adenocarcinoma. Here, we describe the generation of a progressive and metastatic pancreatic cancer mouse model after the somatic and sporadic delivery of avian retroviruses encoding the mouse polyoma virus middle T antigen to elastase-tv-a transgenic mice with a pancreas-specific deletion of the Trp53 tumor suppressor locus. In this model, the tumors metastasize most frequently to the liver, consistent with human pancreatic carcinomas. Analysis of metastatic lesions demonstrated that concomitant loss of the Ink4a/Arf locus was not required for metastasis; however, pancreas-specific deletion of a single Ink4a/Arf allele cooperated with Trp53 deletion in a haploinsufficient manner to accelerate tumor development. Thus, our findings illustrate the potential role of p53 loss of function in pancreatic tumor progression, demonstrate the feasibility of modeling pancreatic cancer metastasis after somatic and sporadic oncogene activation, and indicate that our model may provide a useful experimental system for investigation of the molecular mechanisms underlying pancreatic cancer progression and metastasis.
