53 results on '"D. LaBrecque"'
Search Results
2. Low-Impedance Physical Human-Robot Interaction Using an Active-Passive Dynamics Decoupling.
- Author
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Pascal D. Labrecque, Jacques-Michel Hache, Muhammad E. Abdallah, and Clément Gosselin
- Published
- 2016
- Full Text
- View/download PDF
3. Robotic force amplification with free space motion capability.
- Author
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Pascal D. Labrecque and Clément Gosselin
- Published
- 2014
- Full Text
- View/download PDF
4. From the Brain to the Hand: electrophysiological correlates of language-induced motor activity
- Author
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F Pérez--Gay Juárez, D Labrecque, and V Frak
- Published
- 2018
- Full Text
- View/download PDF
5. Reservoir Monitoring in Oil Sands Using a Permanent Cross-well System: Status and Results after 18 Months of Production
- Author
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S. Dümmong, R. Godfrey, D. LaBrecque, H. Schütt, R. Tondel, J. Ingham, and A. Ducrocq
- Subjects
Regional geology ,Hydrogeology ,Petroleum engineering ,Engineering geology ,Oil sands ,Electrical resistivity tomography ,Economic geology ,Vertical seismic profile ,Geomorphology ,Geology ,Steam-assisted gravity drainage - Abstract
A joint research project between Statoil and Schlumberger is focusing on permanent cross-well geophysical methods for reservoir monitoring during steam assisted gravity drainage (SAGD). A feasibility study indicated detectable differences in seismic and electrical reservoir properties based on expected changes in temperature and fluid saturation during oil production. Based on these results, a permanent cross-well system was installed at Statoil’s Leismer Demonstration Area (LDA) in Alberta, Canada. Baseline datasets, including cross-well seismic, 3D vertical seismic profiling (VSP) and cross-well electrical resistivity tomography (ERT), have been acquired. Comparisons between conventional surface seismic and downhole seismic data show an increase in resolution and frequency content as expected. The ERT baseline shows clear separation between zones of high and low electrical resistivity. Several time-lapse studies have been carried out over the last year, and production-induced time-lapse effects are observed in the reservoir section, both for the time-lapse 3D VSP and ERT datasets. Continuous remote ERT monitoring and annual 3D VSP acquisitions will give the potential of each data type as monitoring tools for oil sand reservoir, as well as possibilities for integrating acoustic and electric data.
- Published
- 2013
- Full Text
- View/download PDF
6. Borehole EM Monitoring at Aquistore: Final Report to the Carbon Capture Project (CCP)
- Author
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J.T. Smith, J.H. Beyer, T. Daley, and D. LaBrecque
- Subjects
Engineering ,Petroleum engineering ,Operations research ,business.industry ,Borehole ,National laboratory ,business - Abstract
Borehole EM Monitoring at Aquistore Final Report to the Carbon Capture Project (CCP) Thomas M. Daley, J. Torquil Smith, John Henry Beyer (all at Lawrence Berkeley National Laboratory) and Douglas LaBrecque (Multi‐Phase Technologies, LLC)
- Published
- 2012
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7. Permanent Downhole Electrical Resistivity Tomography in the Focus of long-term CO2 Monitoring at the Ketzin Pilot Site
- Author
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T. Labitzke, P. Bergmann, C. Schmidt-Hattenberger, Hartmut Schütt, Carsten Rücker, and D. LaBrecque
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Regional geology ,Hydrogeology ,Petroleum engineering ,Engineering geology ,Borehole ,550 - Earth sciences ,Electrical resistivity tomography ,Economic geology ,Petrology ,Geology ,Term (time) ,Environmental geology - Abstract
The permanently installed vertical electrical resistivity array (VERA) as part of the multi-disciplinary surveillance concept of the Ketzin pilot site represents an interesting object for long-term monitoring and verification studies. A practical workflow has been established to qualify the acquired data considering site specific, operational and technical circumstances. An independently performed electrode test was carried out in order to investigate the behaviour of the individual borehole electrodes. In the present stage, consolidated data sets are available from which preliminary CO2 saturation maps have been derived.
- Published
- 2012
8. ChemInform Abstract: A Novel Regioselective Synthesis of Allylsilanes
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Tak Hang Chan and D. Labrecque
- Subjects
Terpene ,Chemistry ,Organic chemistry ,Regioselectivity ,General Medicine - Abstract
The anions derived from allyl sulfones were silated in the α-position. Reductive desulfonylation gave the desired allylsilanes regioselectively.
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- 2010
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9. ChemInform Abstract: Stereoselective Reactions of α-Silylallyl Anions with Carbonyl Compounds
- Author
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D. Labrecque and Tak Hang Chan
- Subjects
Reaction conditions ,Solvent ,Reaction temperature ,Chemistry ,Stereoselectivity ,General Medicine ,Medicinal chemistry - Abstract
α-silylallyl anions of the type 6 react with carbonyl compounds at the γ-position, and stereoselectively to give the E- or Z-isomer depending on the reaction conditions. Solvent and reaction temperature play a critical role in the controle of stereoselectivity.
- Published
- 2010
- Full Text
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10. Stereoselective reactions of α-silylallyl anions with carbonyl compounds
- Author
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D. Labrecque and Tak Hang Chan
- Subjects
Reaction conditions ,Solvent ,Reaction temperature ,Chemistry ,Organic Chemistry ,Drug Discovery ,Organic chemistry ,Stereoselectivity ,Reaction intermediate ,Solvent effects ,Biochemistry ,Carbanion - Abstract
α-silylallyl anions of the type 6 react with carbonyl compounds at the γ-position, and stereoselectively to give the E- or Z-isomer depending on the reaction conditions. Solvent and reaction temperature play a critical role in the controle of stereoselectivity.
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- 1992
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11. A novel regioselective synthesis of allylsilanes
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D. Labrecque and Tak Hang Chan
- Subjects
Chemistry ,Organic Chemistry ,Drug Discovery ,Regioselectivity ,Organic chemistry ,Biochemistry - Abstract
The anions derived from allyl sulfones were silated in the α-position. Reductive desulfonylation gave the desired allylsilanes regioselectively.
- Published
- 1991
- Full Text
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12. A new electrode switching system (ESS) and a scheme for measurement of the movement of buried objects
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R Versteeg, Zhihua Li, D LaBrecque, and Bruce L. Kutter
- Subjects
Scheme (programming language) ,Engineering ,Movement (music) ,business.industry ,Electrode ,Electronic engineering ,business ,computer ,computer.programming_language - Published
- 2006
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13. Recombinant hepatitis A virus antigen: improved production and utility in diagnostic immunoassays
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Stanley Perlman, J. B. Cederna, J.-Q. Han, Donna Klinzman, Patricia L. Winokur, Douglas R. LaBrecque, F. D. LaBrecque, and Jack T. Stapleton
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Microbiology (medical) ,viruses ,Recombinant Fusion Proteins ,Population ,Radioimmunoassay ,Enzyme-Linked Immunosorbent Assay ,Vaccinia virus ,Hepatitis A Antigens ,Antibodies, Viral ,Sensitivity and Specificity ,Serology ,law.invention ,Cell Line ,Virus-like particle ,Antigen ,law ,Virology ,medicine ,Animals ,Humans ,education ,Antigens, Viral ,education.field_of_study ,biology ,medicine.diagnostic_test ,fungi ,virus diseases ,biochemical phenomena, metabolism, and nutrition ,Hepatitis A ,digestive system diseases ,Immunoassay ,Recombinant DNA ,biology.protein ,Antibody ,Hepatitis A Virus, Human - Abstract
Hepatitis A virus (HAV) immunoassays use cell culture-derived HAV antigen to detect HAV-specific antibodies. The current method of production of HAV antigen in tissue culture is time-consuming and expensive. We previously expressed the HAV open reading frame in recombinant vaccinia viruses (rV-ORF). The recombinant HAV polyprotein was accurately processed and was assembled into subviral particles. These particles were bound by HAV-neutralizing antibodies and were able to elicit antibodies which were detected by commercial immunoassays. The present investigation compared the production of HAV antigen by standard tissue culture methods to the production of HAV antigen with the recombinant vaccinia virus system. In addition, HAV and rV-ORF antigens were assessed for their utility in diagnostic immunoassays. Serum or plasma samples from HAV antibody-positive and antibody-negative individuals were evaluated by immunoassay that used either HAV or rV-ORF antigen. All samples (86 of 86) in which HAV antibody was detected by a commercial enzyme-linked immunosorbent assay (ELISA) also tested positive by the recombinant antigen-based immunoassay (VacRIA). Similarly, all samples (50 of 50) that were HAV antibody negative also tested negative by the VacRIA. The lower limit of detection of HAV antibody was similar among immunoassays with either HAV or rV-ORF antigen. Thus, in the population studied, the sensitivity and specificity of the VacRIA were equivalent to those of the commercial ELISA. Since production of recombinant antigen is faster and less expensive than production of traditional HAV antigen, the development of diagnostic HAV antibody tests with recombinant HAV antigen appears warranted.
- Published
- 1998
14. A hybrid hydrologic-geophysical inverse technique for the assessment and monitoring of leachates in the vadose zone. 1998 annual progress report
- Author
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R.J. Glass, T.C. Yeh, David Alumbaugh, and D. LaBrecque
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Hydrology ,Remedial action ,Engineering ,Hydrogeology ,Flow conditions ,business.industry ,Field experiment ,Vadose zone ,Inverse ,Geophysics ,business ,Water content ,Field (geography) - Abstract
'The objective of this study is to develop and field test a new, integrated Hybrid Hydrologic-Geophysical Inverse Technique (HHGIT) for characterization of the vadose zone at contaminated sites. This new approach to site characterization and monitoring can provide detailed maps of hydrogeological heterogeneity and the extent of contamination by combining information from electric resistivity tomography (ERT) surveys, statistical information about heterogeneity and hydrologic processes, and sparse hydrologic data. Because the electrical conductivity of the vadose zone (from the ERT measurements) can be correlated to the fluid saturation and/or contaminant concentration, the hydrologic and geophysical measurements are related. As of the 21st month of a 36-month project, a three-dimensional stochastic hydrologic inverse model for heterogeneous vadose zones has been developed. This model employs pressure and moisture content measurements under both transient and steady flow conditions to estimate unsaturated hydraulic parameters. In this model, an innovative approach to sequentially condition the estimate using temporal measurements has been incorporated. This allows us to use vast amounts of pressure and moisture content information measured at different times while keeping the computational effort manageable. Using this model the authors have found that the relative importance of the pressure and moisture content measurements in defining the different vadose zone parameters depends on whether the soil is wet or dry. They have also learned that pressure and moisture content measurements collected during steady state flow provide the best characterization of heterogeneity compared to other types of hydrologic data. These findings provide important guidance to the design of sampling scheme of the field experiment described below.'
- Published
- 1998
- Full Text
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15. A model to examine the validity of the 6-month abstinence criterion for liver transplantation
- Author
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W R, Yates, M, Martin, D, LaBrecque, D, Hillebrand, M, Voigt, and D, Pfab
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Adult ,Male ,Time Factors ,Psychometrics ,Temperance ,Eligibility Determination ,Reproducibility of Results ,Middle Aged ,Personality Assessment ,Liver Transplantation ,Alcoholism ,Treatment Outcome ,Liver Cirrhosis, Alcoholic ,Recurrence ,Humans ,Female - Abstract
Six months of abstinence from alcohol is a commonly used criterion for liver transplantation eligibility for patients with alcoholic cirrhosis. There is limited evidence to document the validity of this criterion with regard to risk of alcoholism relapse. Ninety-one patients with alcoholic cirrhosis were interviewed for relapse risk using the High Risk Alcoholism Relapse (HRAR) Scale. The HRAR model can be used to predict relapse risk independent of duration of sobriety and therefore can be used to examine the validity of the 6 months of abstinence criteria in this clinical population. The two methods demonstrated poor to fair agreement. Agreement was highest with a cutoff allowing a 5% 6-month relapse risk when 79% agreement (c = 0.56) was demonstrated between the two methods. Using the 6-month abstinence criterion alone disallows a significant number of candidates who have a low relapse risk based on their HRAR score. The validity of the 6-month abstinence criterion is supported somewhat by comparison with the HRAR model. However, use of the 6-month abstinence criterion alone forces a significant number of patients with a low relapse risk by HRAR to wait for transplant listing. A relapse risk model based on an estimate of alcoholism severity in addition to duration of sobriety may more accurately select patients who are most likely to benefit from liver transplantation.
- Published
- 1998
16. Transplantation of patients with alcoholic liver disease
- Author
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T, Gerdes, W, Yates, M, Martin, and D, LaBrecque
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Health Care Rationing ,Recurrence ,Risk Factors ,Humans ,Iowa ,Liver Diseases, Alcoholic ,United States ,Liver Transplantation - Published
- 1994
17. Liver regeneration: a picture emerges from the puzzle
- Author
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D, LaBrecque
- Subjects
Hepatocyte Growth Factor ,Humans ,Growth Substances ,Liver Regeneration - Abstract
Liver regeneration remains a fascinating enigma. Many pieces of the puzzle have been elucidated, but as each piece is discovered, it is found to be composed of many smaller pieces, some of which are missing, and the multiple interlocking edges with other pieces of the puzzle remain poorly understood. The true initiating event or events remain unclear. The essential requirement for activation of immediate early genes is generally unchallenged. C-jun is essential for normal hepatogenesis in mouse development and it appears to be required for proliferation in response to injury, as well. Yet, nefenopin and cyproterone acetate induce hyperplastic responses in the liver with no induction of c-fos, c-myc, or c-jun. HGF is the single most potent liver mitogen yet discovered. However, levels of HGF do not correlate with the degree of liver regeneration, and high concentrations exist in conditions such as those in chronic hemodialysis patients who have no evidence of regeneration and minimal evidence of liver injury. Numerous conditions exist that induce immediate early genes and yet do not lead to cell proliferation. Thus, the availability of mitogens by themselves is not sufficient to induce regeneration, and the induction of immediate early genes is not sufficient to lead to regeneration. Whereas the isolated parenchymal cell culture system has been extremely valuable in identifying an increasing number of stimulatory and inhibitory substances and identifying the initial steps in their mechanisms of action, this simple system does not take into account the extremely complex interactions of these multiple growth factors in vivo and the interaction of the parenchymal cell with the other cellular and structural components of the liver. All must be accounted for in a complete model of liver regeneration. Parenchymal cell growth itself appears to be controlled by a series of steps, each of which requires the presence of specific growth regulators, which may be stimulators or inhibitors. There is a strictly defined sequence that must be followed, and if one or more of the factors is missing at the essential time point, growth will not progress and the cell will return to the G0 phase or proceed to apoptosis and death. While all this is occurring, the liver must also continue to carry out its essential life-supporting functions. And, finally, the liver must somehow know when to stop. Over-expression of some growth factors, such as TGF alpha, appears to produce tumors, whereas overexpression of others, such as HGF, does not.(ABSTRACT TRUNCATED AT 400 WORDS)
- Published
- 1994
18. Gif oxidation of some alicyclic amines
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Jean Boivin, K. Jankowski, D. Labrecque, and D. Gaudin
- Subjects
chemistry.chemical_classification ,Bicyclic molecule ,Trace Amounts ,Organic Chemistry ,chemistry.chemical_element ,Zinc ,Biochemistry ,Catalysis ,Acetic acid ,chemistry.chemical_compound ,Alicyclic compound ,chemistry ,Drug Discovery ,Pyridine ,Lactam ,Organic chemistry - Abstract
The Gif oxidation of seven alicyclic tertiary amines leads essentially to the formation of lactams. The structure of the products present in trace amounts supports the mechanistic hypothesis previously advanced. The structures of the oxidation products were investigated using high performance GC-MS system.
- Published
- 1990
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19. Neonatal seizure recurrence following discontinuation of phenobarbital
- Author
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D, Labrecque, P, Gal, and M K, Sharpless
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Male ,Electrocardiography ,Pregnancy ,Recurrence ,Seizures ,Phenobarbital ,Infant, Newborn ,Humans ,Female ,Gestational Age ,Drug Administration Schedule - Abstract
The recurrence of seizures in neonates following discontinuation of phenobarbital was studied. All neonates treated for seizures in the intensive care nursery over a period of four years were followed for seizure recurrence after discharge from the hospital. Of 64 neonates treated for seizures, 50 were followed until they were at least 12 months of age. Their charts were reviewed for birth date, birth weight, gestational age, Apgar scores, age at seizure onset, seizure type, seizure etiology, duration of anticonvulsant therapy, and any neurologic deficits. Information on seizure activity and neurologic and developmental status was obtained through clinic observation or telephone interviews with parents and pediatricians. Anticonvulsant therapy was continued for 4 to 97 days; however, 85% of patients were treated less than three weeks. Those treated longer than three weeks either could not be withdrawn from anticonvulsants or were premature infants who had prolonged, severe illness. The length of follow-up ranged from 12 to 47 months, the average follow-up age being 24 months. Six patients were found to require long-term anticonvulsants because of persistent or recurring seizures. The severity of neurologic damage was a good predictor of seizure recurrence. The duration of anticonvulsant therapy in neonates should be limited to the period when the neonate is acutely ill.
- Published
- 1984
20. Promotion of monolayer formation in cultured whole pancreatic islets by 3-isobutyl-1-methylxanthine
- Author
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H Ohgawara, C Hofmann, Y Hirata, Raymond J. Carroll, Allen D. Labrecque, M Kikuchi, C Takahashi, and Donald F. Steiner
- Subjects
geography ,Multidisciplinary ,geography.geographical_feature_category ,3-Isobutyl-1-methylxanthine ,Phosphodiesterase Inhibitors ,Pancreatic islets ,Enteroendocrine cell ,Biology ,Islet ,Cell biology ,Rats ,Islets of Langerhans ,medicine.anatomical_structure ,Glucose ,Biochemistry ,Xanthines ,Monolayer ,medicine ,Endocrine system ,Animals ,Phosphodiesterase inhibitor ,Fibroblast ,Cells, Cultured ,Research Article - Abstract
Normal adult rat islets usually remained intact and encapsulated, even after many days in culture. In contrast, islets cultured in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (0.1 mM) attached more readily to the surface of plastic culture dishes and almost uniformly formed monolayers of endocrine cells. The mechanism of this effect is not known but presumably involves increases in cellular cyclic AMP content. Fibroblast growth did not appear to be stimulated by the inhibitor. These adult pancreatic endocrine monolayer cultures can be produced readily and provide useful preparations for further morphological and biochemical studies of factors affecting the differentiation, growth, and regenerative capacity of islet cells.
- Published
- 1978
21. PRECURSORS IN THE BIOSYNTHESIS OF INSULIN AND OTHER PEPTIDE HORMONES
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C. Patzelt, P.S. Quinn, Donald F. Steiner, Barbara E. Noyes, S. J. Chan, Pamela S. Keim, Allen D. Labrecque, Robert L. Heinrikson, and John R. Duguid
- Subjects
Preproinsulin ,biology ,medicine.diagnostic_test ,Endoplasmic reticulum ,Proteolysis ,Insulin ,medicine.medical_treatment ,Translation (biology) ,Carboxypeptidase ,Biochemistry ,biology.protein ,medicine ,Polyadenylate ,Proinsulin - Abstract
SUMMARY Recent studies have established that limited intracellular proteolysis may participate at several stages in the biosynthesis of many small polypeptide hormones, as exemplified by insulin. Conversion of proinsulin to insulin by trypsin-and carboxypeptidase B-like enzymes occurs in the pancreatic B cell after the peptide has been sequestered from the cytosolic compartment and transported to the Golgi area. An earlier role for proteolysis concerns the conversion of the initial translation product, preproinsulin, to proinsulin during its compartmentalization in the rough endoplasmic reticulum. Preproinsulin, a methionine-initiated peptide which contains a hydrophobic 24-residue NH 2 -terminal extension, was originally identified as the product of the cell-free translation of insulin mRNA, but more recently it has also been detected in small amounts in intact rat islets. Its rapid formation and disappearance during pulse-chase studies are consistent with its role as a biosynthetic precursor and with the proposal that the prepeptide region serves as a leader sequence in the formation of the ribosome-membrane junction and in the vectorial discharge of the peptide. A model for segregation is presented, based on important structural features and physical properties of the prepeptides which may enable these to enter and span the microsomal membrane. Studies on insulin mRNA obtained from transplantable islet cell tumors indicate that the major component contains approximately 600 nucleotides and possesses a 5′ “cap” structure as well as a 3′ polyadenylate “tail”. A closer examination of the insulin tumor mRNA has also revealed two larger polyadenylated RNA fractions having apparent molecular weights of 280,000 and 360,000. These forms, which hybridize to the rat insulin genes and which were shown by ribonuclease T 1 digests to share nucleotide sequences with the major mRNA component, may represent precursors of the mature template. These results indicate that several sequential stages of macromolecular processing are required in the formation of the secreted hormone.
- Published
- 1979
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22. Cloned cell lines from a transplantable islet cell tumor are heterogeneous and express cholecystokinin in addition to islet hormones
- Author
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Thue W. Schwartz, Ole D. Madsen, L.-I. Larsson, A. Lernmark, A D Labrecque, Donald F. Steiner, and Jens F. Rehfeld
- Subjects
medicine.medical_specialty ,endocrine system ,Dilution cloning ,Cellular differentiation ,medicine.medical_treatment ,Cell ,Peptide hormone ,Biology ,Internal medicine ,medicine ,Animals ,Insulin ,Cholecystokinin ,geography ,geography.geographical_feature_category ,fungi ,Liver Neoplasms ,Cell Biology ,Articles ,Islet ,Adenoma, Islet Cell ,Glucagon ,Molecular biology ,Rats ,Pancreatic Neoplasms ,Endocrinology ,medicine.anatomical_structure ,Cell culture ,Stem cell ,Somatostatin - Abstract
A liver metastasis (MSL) with a remarkable in vitro proliferation potential has been identified in an NEDH rat carrying a transplantable x-ray-induced islet cell tumor. Two insulin-secreting cell lines, MSL-G and MSL-H, with doubling times of 3-5 d were established by repeated limiting dilution cloning. In vivo inoculation of MSL-G cells induced severe hypoglycemia caused by a small but highly heterogeneous tumor as revealed by immunocytochemistry. Whereas most cells stained for the islet hormones, insulin, glucagon, and somatostatin, clustered cells were discovered to contain cholecystokinin (CCK). Additional in vitro-limiting dilution cloning, followed by immunocytochemical characterization, clearly demonstrated the capacity of single cell clones to simultaneously express the same four hormones. Radioimmunoassays with a panel of site-specific antisera of culture supernatants and purified cell extracts showed the MSL-G2 cells to produce, store, and secrete readily detectable amounts of processed and unprocessed CCK. Gastrin was not detected while coexpression of glucagon and CCK were demonstrated. Mutant clones selected for resistance to 6-thioguanine (frequency, 2 X 10(-7] and checked for HAT (hypoxanthine, aminopterin, thymidine) sensitivity retained the capacity for multi-hormone expression. We propose that the MSL tumor contains pluripotent endocrine stem cells. The MSL tumor and the MSL-G2 cells in particular will allow studies of not only CCK biosynthesis and processing but also of mechanisms involved in tumor and islet cell differentiation.
- Published
- 1986
23. Detection and kinetic behavior of preproinsulin in pancreatic islets
- Author
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C. Patzelt, Raymond J. Carroll, John R. Duguid, Donald F. Steiner, Allen D. Labrecque, Pamela S. Keim, and Robert L. Heinrikson
- Subjects
Preproinsulin ,endocrine system ,Peptide ,Biology ,Islets of Langerhans ,medicine ,Animals ,Insulin ,Amino Acid Sequence ,Protein Precursors ,Peptide sequence ,Proinsulin ,Gel electrophoresis ,chemistry.chemical_classification ,geography ,Multidisciplinary ,geography.geographical_feature_category ,Pancreatic islets ,Neoplasms, Experimental ,Islet ,Adenoma, Islet Cell ,Peptide Fragments ,Rats ,Pancreatic Neoplasms ,Kinetics ,medicine.anatomical_structure ,Glucose ,chemistry ,Biochemistry ,Leucine ,hormones, hormone substitutes, and hormone antagonists ,Research Article - Abstract
Newly synthesized rat islet proteins have been analyzed by polyacrylamide slab gel electrophoresis and fluorography. A minor component having an apparent molecular weight of 11,100 was identified as preproinsulin by the sensitivity of its synthesis to glucose, the pattern of NH2-terminal leucine residues, and the rapidity of its appearance and disappearance during incubation of islets or islet cell tumors. A small amount of labeled peptide material which may represent the excised NH2-terminal extension of preproinsulin or its fragment was also detected. The kinetics of formation and processing of the preproinsulin fraction were complex, consisting of a rapidly turning over component having a half-life of about 1 min and a slower minor fraction that may have bypassed the normal cleavage process. The electrophoretic resolution of the preproinsulin and proinsulin fractions into two bands each is consistent with the presence of two closely related gene products in rat islets rather than intermediate stages in the processing of these peptides.
- Published
- 1978
24. The incidence of mammary tumors in germ-free C3H mice
- Author
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H I, Pilgrim and A D, Labrecque
- Subjects
Mice ,Animals ,Germ-Free Life ,Mammary Neoplasms, Experimental - Published
- 1967
25. Consensus Paper: Situated and Embodied Language Acquisition.
- Author
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Reggin LD, Gómez Franco LE, Horchak OV, Labrecque D, Lana N, Rio L, and Vigliocco G
- Abstract
Theories of embodied cognition postulate that perceptual, sensorimotor, and affective properties of concepts support language learning and processing. In this paper, we argue that language acquisition, as well as processing, is situated in addition to being embodied. In particular, first, it is the situated nature of initial language development that affords for the developing system to become embodied. Second, the situated nature of language use changes across development and adulthood. We provide evidence from empirical studies for embodied effects of perception, action, and valence as they apply to both embodied cognition and situated cognition across developmental stages. Although the evidence is limited, we urge researchers to consider differentiating embodied cognition within situated context, in order to better understand how these separate mechanisms interact for learning to occur. This delineation also provides further clarity to the study of classroom-based applications and the role of embodied and situated cognition in the study of developmental disorders. We argue that theories of language acquisition need to address for the complex situated context of real-world learning by completing a "circular notion": observing experimental paradigms in real-world settings and taking these observations to later refine lab-based experiments., Competing Interests: The authors have no competing interests to declare., (Copyright: © 2023 The Author(s).)
- Published
- 2023
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26. Action verbs drive motor activity in adolescents but not in children.
- Author
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Frak V, Labrecque D, and Cohen H
- Subjects
- Adolescent, Adult, Child, Hand Strength, Humans, Language, Motor Activity, Hand, Semantics
- Abstract
In adults, grip force has reliably been used to investigate motor simulation evoked by linguistic action, suggesting that motor phenomena are linked to semantic action. The parietal and frontal lobes and their connexions are essential neural structures for pragmatic aspects of hand semantic action. In this perspective, the aim of the study was to determine the extent to which two groups of children and adolescents, classically characterized by degree of axonal myelination in fronto-parietal circuits, monitored the occurrence of nouns and manual action verbs presented auditorily while holding a grip force sensor. Differential effects of grip force were seen only in the adolescents when monitoring action verbs. Interestingly, weaker effects of grip force were modulated by noun targets only in the younger children, revealing that the ability to profit from a full semantic representation of verbs is not clearly established in the younger children. Grip force modulation was observed as early as 300 ms post target onset and peaked at the 500-750 ms window of observation for both groups. These group differences are in line with the motor simulation difficulties seen in younger children. The results may also indicate that degree of grip force in response to specific linguistic categories parallels the maturation of the parietal-frontal circuits, including the anterior intra-parietal area which plays a determining role in semantic aspects of hand action., (Copyright © 2020 Elsevier Inc. All rights reserved.)
- Published
- 2021
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27. WGO Guidance for the Care of Patients With COVID-19 and Liver Disease.
- Author
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Hamid S, Alvares da Silva MR, Burak KW, Chen T, Drenth JPH, Esmat G, Gaspar R, LaBrecque D, Lee A, Macedo G, McMahon B, Ning Q, Reau N, Sonderup M, van Leeuwen DJ, Armstrong D, and Yurdaydin C
- Subjects
- COVID-19 diagnosis, COVID-19 physiopathology, Humans, Infection Control methods, Liver Diseases diagnosis, Liver Diseases physiopathology, Prognosis, Risk Factors, COVID-19 complications, COVID-19 therapy, Liver Diseases therapy, Liver Diseases virology
- Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the least deadly but most infectious coronavirus strain transmitted from wild animals. It may affect many organ systems. Aim of the current guideline is to delineate the effects of SARS-CoV-2 on the liver. Asymptomatic aminotransferase elevations are common in coronavirus disease 2019 (COVID-19) disease. Its pathogenesis may be multifactorial. It may involve primary liver injury and indirect effects such as "bystander hepatitis," myositis, toxic liver injury, hypoxia, and preexisting liver disease. Higher aminotransferase elevations, lower albumin, and platelets have been reported in severe compared with mild COVID-19. Despite the dominance of respiratory disease, acute on chronic liver disease/acute hepatic decompensation have been reported in patients with COVID-19 and preexisting liver disease, in particular cirrhosis. Metabolic dysfunction-associated fatty liver disease (MAFLD) has a higher risk of respiratory disease progression than those without MAFLD. Alcohol-associated liver disease may be severely affected by COVID-19-such patients frequently have comorbidities including metabolic syndrome and smoking-induced chronic lung disease. World Gastroenterology Organization (WGO) recommends that interventional procedures such as endoscopy and endoscopic retrograde cholangiopancreatography should be performed in emergency cases or when they are considered strictly necessary such as high risk varices or cholangitis. Hepatocellular cancer surveillance may be postponed by 2 to 3 months. A short delay in treatment initiation and non-surgical approaches should be considered. Liver transplantation should be restricted to patients with high MELD scores, acute liver failure and hepatocellular cancer within Milan criteria. Donors and recipients should be tested for SARS-CoV-2 and if found positive donors should be excluded and liver transplantation postponed until recovery from infection.
- Published
- 2021
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28. Assessing language-induced motor activity through Event Related Potentials and the Grip Force Sensor, an exploratory study.
- Author
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Pérez-Gay Juárez F, Labrecque D, and Frak V
- Subjects
- Adult, Female, Humans, Male, Auditory Perception physiology, Evoked Potentials physiology, Hand Strength physiology, Language, Motor Activity physiology
- Abstract
The link between language processing and motor systems has been the focus of increasing interest to Cognitive Neuroscience. Some classical papers studying Event Related Potentials (ERPs) induced by linguistic stimuli have found differences in electrophysiological activity when comparing action and non-action words; more specifically, a bigger p200 for action words. On the other hand, a series of studies have validated the use of a grip force sensor (GFS) to measure language-induced motor activity during both isolated words and sentence listening, finding that action words induce an augmentation in the grip force around 250-300 ms after the onset of the stimulus. The purpose of the present study is to combine both techniques to assess if the p200 is related to the augmentation of the grip force measured by a GFS. We measured ERP and GFS changes elicited by listening to action and non-action words while maintaining an active grasping task. Our results show that both the p200 and the grip force around 300 ms are bigger for action words, compared to non-action. We also report a statistical correlation between these measures. To our knowledge, this is the first study where the electrophysiological activity and the changes in the grip force induced by auditory language processing are put together, opening new venues of interpretation for the sensorimotor interaction in language processing., (Copyright © 2019 Elsevier Inc. All rights reserved.)
- Published
- 2019
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29. Confusion for Fifteen Years: A Case of Abernethy Malformation.
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Soota K, Klair JS, and LaBrecque D
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- Adult, Humans, Male, Radiography, Abdominal, Tomography, X-Ray Computed, Splanchnic Circulation, Vascular Malformations diagnosis, Vascular Malformations pathology, Veins pathology
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- 2018
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30. Manual action verbs modulate the grip force of each hand in unimanual or symmetrical bimanual tasks.
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da Silva RL, Labrecque D, Caromano FA, Higgins J, and Frak V
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- Adult, Female, Humans, Male, Middle Aged, Young Adult, Functional Laterality, Hand Strength
- Abstract
Manual action verbs modulate the right-hand grip force in right-handed subjects. However, to our knowledge, no studies demonstrate the ability to accomplish this modulation during bimanual tasks nor describe their effect on left-hand behavior in unimanual and bimanual tasks. Using load cells and word playlists, we evaluated the occurrence of grip force modulation by manual action verbs in unimanual and symmetrical bimanual tasks across the three auditory processing phases. We found a significant grip force increase for all conditions compared to baseline, indicating the occurrence of modulation. When compared to each other, the grip force variation from baseline for the three phases of both hands in the symmetrical bimanual task was not different from the right-hand in the unimanual task. The left-hand grip force showed a lower amplitude for auditory phases 1 and 2 when compared to the other conditions. The right-hand grip force modulation became significant from baseline at 220 ms after the word onset in the unimanual task. This moment occurred earlier for both hands in bimanual task (160 ms for the right-hand and 180 for the left-hand). It occurred later for the left-hand in unimanual task (320 ms). We discuss the hypothesis that Broca's area and Broca's homologue area likely control the left-hand modulation in a unilateral or a bilateral fashion. These results provide new evidence for understanding the linguistic function processing in both hemispheres.
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- 2018
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31. The impact of an educational program on HCV patient outcomes using boceprevir in community practices (OPTIMAL trial).
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Poordad F, Rustgi V, Brown RS Jr, Patel V, Kugelmas M, Regenstein F, Balart L, LaBrecque D, Brown K, Avila M, Biederman M, Freed G, Smith R, Bernstein M, Arnold H, Cahan J, Fink S, Katkov W, Massoumi H, and Harrison S
- Abstract
Objectives: Although effective, direct acting antiviral (DAA) therapies for genotype 1 (GT 1) hepatitis C virus (HCV) have been associated with compliance challenges. Additionally, treatment at predominantly community-based centers has been associated with low retention of patients on treatment and higher dropout rates. The OPTIMAL Phase IV interventional trial (ClinicalTrials.gov Identifier: NCT01405027) was designed to evaluate the impact of an education program for community investigator (CI) sites participating in a Chronic Liver Disease Foundation study treating chronic GT 1 HCV patients., Methods: This physician educational program was administered by 22 Hepatology Centers of Educational Expertise (HCEE) academic sites to 33 CI sites asked to participate from December 2011 to July 2012. The HCEE mentors from DAA-experienced academic sites educated those at CI sites on therapeutic management, practice, and patient outcomes through a series of four standardized educational sequence visits regarding the use of first generation HCV protease inhibitors and the overall treatment of HCV., Results: Treatment duration compliance rates for patients treated at CI sites versus those treated at HCEE academic sites were evaluable in 77 of 84 HCEE academic site patients, 102 of 113 patients treated at CI sites, and 179 of 197 overall patients. The treatment duration compliance rates for patients treated at HCEE academic sites, CI sites and overall were 85.4 ± 25.39%, 83.8 ± 27.37%, and 84.5 ± 26.48%, respectively, and did not differ statistically between the groups (p = 0.49). Almost half (47%) of the patients in the study achieved a sustained virological response for 24 weeks (SVR24) regardless of the type of site (p = 0.64). Safety profiles were similar at both HCEE and CI sites., Conclusions: These results demonstrated that education of CI sites unfamiliar with DAAs resulted in patient outcomes consistent with those observed at DAA-experienced academic sites.
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- 2015
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32. World Gastroenterology Organisation global guidelines: diagnosis, management and prevention of hepatitis C April 2013.
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Umar M, Khan AG, Abbas Z, Arora S, Asifabbas N, Elewaut A, Esmat G, Foster G, Fried M, Goh KL, Hamama TB, Imawari M, Isakov V, Krabshuis J, LaBrecque D, Lemair A, Malfertheiner P, Ryder S, Schiedermaier P, Stimac D, Tandon R, Villamil F, Zapata R, and Ferenci P
- Subjects
- Drug Therapy, Combination, Humans, Predictive Value of Tests, Risk Factors, Treatment Outcome, Antiviral Agents therapeutic use, Hepatitis C diagnosis, Hepatitis C drug therapy, Hepatitis C epidemiology, Hepatitis C prevention & control
- Published
- 2014
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- View/download PDF
33. Discovery of spirofused piperazine and diazepane amides as selective histamine-3 antagonists with in vivo efficacy in a mouse model of cognition.
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Brown DG, Bernstein PR, Griffin A, Wesolowski S, Labrecque D, Tremblay MC, Sylvester M, Mauger R, Edwards PD, Throner SR, Folmer JJ, Cacciola J, Scott C, Lazor LA, Pourashraf M, Santhakumar V, Potts WM, Sydserff S, Giguère P, Lévesque C, Dasser M, and Groblewski T
- Subjects
- Animals, Azetidines chemical synthesis, Azetidines pharmacokinetics, Azetidines pharmacology, CHO Cells, Cell Membrane Permeability, Cricetinae, Cricetulus, Cyclopropanes pharmacokinetics, Cyclopropanes pharmacology, Dogs, Histamine H3 Antagonists pharmacokinetics, Histamine H3 Antagonists pharmacology, Humans, Learning drug effects, Madin Darby Canine Kidney Cells, Male, Mice, Microsomes, Liver metabolism, Models, Molecular, Piperazines pharmacokinetics, Piperazines pharmacology, Piperidines chemical synthesis, Piperidines pharmacokinetics, Piperidines pharmacology, Pyrrolidines chemical synthesis, Pyrrolidines pharmacokinetics, Pyrrolidines pharmacology, Rats, Rats, Sprague-Dawley, Receptors, Histamine H3 genetics, Recognition, Psychology drug effects, Spiro Compounds pharmacokinetics, Spiro Compounds pharmacology, Stereoisomerism, Structure-Activity Relationship, Cognition drug effects, Cyclopropanes chemical synthesis, Histamine H3 Antagonists chemical synthesis, Piperazines chemical synthesis, Receptors, Histamine H3 metabolism, Spiro Compounds chemical synthesis
- Abstract
A new series of potent and selective histamine-3 receptor (H3R) antagonists was identified on the basis of an azaspiro[2.5]octane carboxamide scaffold. Many scaffold modifications were largely tolerated, resulting in nanomolar-potent compounds in the H3R functional assay. Exemplar compound 6s demonstrated a selective profile against a panel of 144 secondary pharmacological receptors, with activity at only σ2 (62% at 10 μM). Compound 6s demonstrated free-plasma exposures above the IC50 (∼50×) with a brain-to-plasma ratio of ∼3 following intravenous dosing in mice. At three doses tested in the mouse novel object recognition model (1, 3, and 10 mg/kg s.c.), 6s demonstrated a statistically significant response compared with the control group. This series represents a new scaffold of H3 receptor antagonists that demonstrates in vivo exposure and efficacy in an animal model of cognition.
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- 2014
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34. Efficient injection of low-mass ions into high magnetic field Fourier transform ion cyclotron resonance mass spectrometers.
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Zekavat B, Szulejko JE, LaBrecque D, Olaitan AD, and Solouki T
- Abstract
Rationale: Low-mass cut-off restrictions for injecting ions from external ion sources into high magnetic fields impose limitations for wide mass range analyses with Fourier transform ion cyclotron resonance (FTICR) instruments. Radio-frequency (RF)-only quadrupole ion guides (QIGs) with higher frequencies can be used to overcome low-mass cut-off in FTICR instruments., Methods: RF signals (1.0 MHz to 10.0 MHz) were applied to QIGs to transfer externally generated ions from either electron ionization (EI) or electrospray ionization (ESI) sources into ICR cells of 9.4 T FTICR mass spectrometers. Efficiencies of QIGs were evaluated using externally generated ions from: EI of acetone, air, and perfluorotributylamine mixture, EI of gas chromatography (GC)-separated components of a standard sample mixture, and ESI of complex mixtures such as petroleum and fulvic acid samples., Results: We were able to transfer ions with m/z as low as 26 from an external EI source into the ICR cell of a 9.4 T FTICR mass spectrometer and extend the operational low-mass range for ESI-FTICR analyses. High mass resolving power and mass measurement accuracy of GC/FTICR mass spectrometry were utilized to discriminate between oxygenated and non-oxygenated compounds in a 'Grob' sample. Ion losses based on SIMION ion trajectory predictions were consistent with experimental findings., Conclusions: We demonstrated that the use of high-frequency QIGs can extend the operational lower m/z range for both external EI- and ESI-FTICR mass spectrometers. By considering both ICR and Mathieu equations of motions to describe ion trajectories, theoretical ion ejection thresholds (consistent with our experimental findings) could be predicted., (Copyright © 2013 John Wiley & Sons, Ltd.)
- Published
- 2014
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35. Potent and orally efficacious benzothiazole amides as TRPV1 antagonists.
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Besidski Y, Brown W, Bylund J, Dabrowski M, Dautrey S, Harter M, Horoszok L, Hu Y, Johnson D, Johnstone S, Jones P, Leclerc S, Kolmodin K, Kers I, Labarre M, Labrecque D, Laird J, Lundström T, Martino J, Maudet M, Munro A, Nylöf M, Penwell A, Rotticci D, Slaitas A, Sundgren-Andersson A, Svensson M, Terp G, Villanueva H, Walpole C, Zemribo R, and Griffin AM
- Subjects
- Amides administration & dosage, Amides chemistry, Animals, Benzothiazoles administration & dosage, Benzothiazoles chemistry, Disease Models, Animal, Dose-Response Relationship, Drug, Humans, Inflammation drug therapy, Molecular Structure, Rats, Recombinant Proteins antagonists & inhibitors, Solubility, Structure-Activity Relationship, Amides pharmacology, Benzothiazoles pharmacology, Pain drug therapy, TRPV Cation Channels antagonists & inhibitors
- Abstract
Benzothiazole amides were identified as TRPV1 antagonists from high throughput screening using recombinant human TRPV1 receptor and structure-activity relationships were explored to pinpoint key pharmacophore interactions. By increasing aqueous solubility, through the attachment of polar groups to the benzothiazole core, and enhancing metabolic stability, by blocking metabolic sites, the drug-like properties and pharmokinetic profiles of benzothiazole compounds were sufficiently optimized such that their therapeutic potential could be verified in rat pharmacological models of pain., (Copyright © 2012 Elsevier Ltd. All rights reserved.)
- Published
- 2012
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36. World Gastroenterology Organisation Guideline. Hepatocellular carcinoma (HCC): a global perspective.
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Ferenci P, Fried M, Labrecque D, Bruix J, Sherman M, Omata M, Heathcote J, Piratsivuth T, Kew M, Otegbayo JA, Zheng SS, Sarin S, Hamid S, Modawi SB, Fleig W, Fedail S, Thomson A, Khan A, Malfertheiner P, Lau G, Carillo FJ, Krabshuis J, and Le Mair A
- Subjects
- Carcinoma, Hepatocellular epidemiology, Humans, Liver Neoplasms epidemiology, Carcinoma, Hepatocellular diagnosis, Carcinoma, Hepatocellular therapy, Gastroenterology standards, Global Health, Liver Neoplasms diagnosis, Liver Neoplasms therapy, Societies, Medical standards
- Published
- 2010
37. Hepatocellular carcinoma (HCC): a global perspective.
- Author
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Ferenci P, Fried M, Labrecque D, Bruix J, Sherman M, Omata M, Heathcote J, Piratsivuth T, Kew M, Otegbayo JA, Zheng SS, Sarin S, Hamid SS, Modawi SB, Fleig W, Fedail S, Thomson A, Khan A, Malfertheiner P, Lau G, Carillo FJ, Krabshuis J, and Le Mair A
- Subjects
- Developed Countries, Developing Countries, Female, Hepatitis B, Chronic complications, Hepatitis C, Chronic complications, Humans, Male, Primary Health Care, Risk Factors, Carcinoma, Hepatocellular epidemiology, Carcinoma, Hepatocellular pathology, Carcinoma, Hepatocellular prevention & control, Carcinoma, Hepatocellular therapy, Global Health, Liver Neoplasms epidemiology, Liver Neoplasms pathology, Liver Neoplasms prevention & control, Liver Neoplasms therapy
- Published
- 2010
- Full Text
- View/download PDF
38. Calcite precipitation dominates the electrical signatures of zero valent iron columns under simulated field conditions.
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Wu Y, Versteeg R, Slater L, and LaBrecque D
- Subjects
- Chemical Precipitation, Ferric Compounds chemistry, Calcium Carbonate chemistry, Electricity, Iron chemistry, Water Movements, Water Pollutants, Chemical metabolism, Water Purification methods
- Abstract
Calcium carbonate is a secondary mineral precipitate influencing zero valent iron (ZVI) barrier reactivity and hydraulic performance. We conducted column experiments to investigate electrical signatures resulting from concurrent CaCO(3) and iron oxides precipitation under simulated field geochemical conditions. We identified CaCO(3) as a major mineral phase throughout the columns, with magnetite present primarily close to the influent based on XRD analysis. Electrical measurements revealed decreases in conductivity and polarization of both columns, suggesting that electrically insulating CaCO(3) dominates the electrical response despite the presence of electrically conductive iron oxides. SEM/EDX imaging suggests that the electrical signal reflects the geometrical arrangement of the mineral phases. CaCO(3) forms insulating films on ZVI/magnetite surfaces, restricting charge transfer between the pore electrolyte and ZVI particles, as well as across interconnected ZVI particles. As surface reactivity also depends on the ability of the surface to engage in redox reactions via charge transfer, electrical measurements may provide a minimally invasive technology for monitoring reactivity loss due to CaCO(3) precipitation. Comparison between laboratory and field data shows consistent changes in electrical signatures due to iron corrosion and secondary mineral precipitation.
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- 2009
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39. A comparison of the low frequency electrical signatures of iron oxide versus calcite precipitation in granular zero valent iron columns.
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Wu Y, Slater L, Versteeg R, and LaBrecque D
- Subjects
- Chemical Precipitation, Corrosion, Environmental Monitoring instrumentation, Environmental Monitoring methods, Calcium Carbonate analysis, Ferric Compounds analysis
- Abstract
Geophysical methods have been proposed as technologies for non-invasively monitoring geochemical alteration in permeable reactive barriers (PRBs). We conducted column experiments to investigate the effect of mineralogy on the electrical signatures resulting from iron corrosion and mineral precipitation in Fe0 columns using (a) Na2SO4, and (b) NaHCO3 plus CaCl2 mixture, solutions. At the influent interface where the reactions were most severe, a contrasting time-lapse electrical response was observed between the two columns. Solid phase analysis confirmed the formation of corrosion halos and increased mineralogical complexity in the corroded sections of the columns compared to the minimal/non-corroded sections. We attribute the contrasting time-lapse signatures to the differences in the electrical properties of the mineral phases formed within the two columns. While newly precipitated/transformed polarizable and semi-conductive iron oxides (mostly magnetite and green rust) increase the polarization and conductivity of the sulfate column, the decrease of both parameters in the bicarbonate column is attributed to the precipitation of non-polarizable and non-conductive calcite. Our results show that precipitate mineralogy is an important factor influencing the electrical properties of the corroded iron cores and must be considered if electrical geophysical methods are to be developed to monitor PRB barrier corrosion processes in situ.
- Published
- 2008
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40. Discovery of 4-aryl-4H-chromenes as a new series of apoptosis inducers using a cell- and caspase-based HTS assay. Part 5: modifications of the 2- and 3-positions.
- Author
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Kemnitzer W, Jiang S, Wang Y, Kasibhatla S, Crogan-Grundy C, Bubenik M, Labrecque D, Denis R, Lamothe S, Attardo G, Gourdeau H, Tseng B, Drewe J, and Cai SX
- Subjects
- Benzopyrans chemistry, Cell Division drug effects, Cell Line, Tumor, Humans, Structure-Activity Relationship, Apoptosis drug effects, Benzopyrans pharmacology, Caspases metabolism
- Abstract
As a continuation of our efforts to discover and develop apoptosis inducing 4-aryl-4H-chromenes as novel anticancer agents, we explored modifications at the 2- and 3-positions. It was found that replacement of the 3-cyano group by an ester, including methyl and ethyl ester, resulted in >200-fold reduction of activity. Conversion of the 2-amino group into an amide or urea resulted in 4- to 10-fold drop of activity. Similarly, converting the 2-amino group into a hydrogen resulted in 4- to 10-fold reduction of activity. Compound 3d was highly active with an EC(50) value of 29 nM and a GI(50) value of 6 nM in T47D cells. Importantly, the 2-H analog 3d was found to be much more stable under acidic conditions compared to the 2-NH(2) analog 3b, suggesting that 2-H analogs might have better bioavailability than the 2-NH(2) analogs.
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- 2008
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41. A cyclosporine-based immunosuppressive regimen may be better than tacrolimus for long-term liver allograft survival in recipients transplanted for hepatitis C.
- Author
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Rayhill SC, Barbeito R, Katz D, Voigt M, Labrecque D, Kirby P, Miller R, Stolpen A, Wu Y, and Schmidt W
- Subjects
- Biopsy, Databases, Factual, Drug Therapy, Combination, Female, Graft Rejection pathology, Graft Survival drug effects, Humans, Longitudinal Studies, Male, Middle Aged, Mycophenolic Acid analogs & derivatives, Mycophenolic Acid therapeutic use, Retrospective Studies, Tacrolimus therapeutic use, Transplantation, Homologous immunology, Transplantation, Homologous physiology, Treatment Outcome, Cyclosporine therapeutic use, Graft Survival physiology, Hepatitis C surgery, Immunosuppressive Agents therapeutic use, Liver Transplantation physiology
- Abstract
Unlabelled: Rapid recurrence of severe hepatitis C (HCV) after liver transplantation is a major barrier to survival of the transplanted liver. While cyclosporine (CsA) in vitro has been shown to suppress HCV replication, an effect is not seen with tacrolimus (Tac). Evidence is inconsistent whether or how this translates to clinical practice. To expand the evidence on this issue, we analyzed graft survival and histological outcomes after liver transplantation for HCV hepatitis., Methods: Using our longitudinal database (1991 onward) graft outcomes for all liver transplant recipients with HCV were evaluated (105 grafts in 97 patients). Severe activity, severe fibrosis, and graft survival were analyzed. All liver biopsies were scored (blinded) according to the Ludwig scale. Immunosuppression was based on prednisone and a calcineurin inhibitor (Tac n = 89, 85%; CsA n = 15, 14%). Comparisons of outcomes using CsA versus Tac therapy were done using survival analysis via the log-rank test., Results: Graft survival was significantly better in the CsA group. Although there was no apparent difference in severe activity (grade 2), there was a statistically significant difference in graft survival without fibrosing cholestatic hepatitis (P = .01) and a trend toward a difference in fibrosis-free survival (P = 0.1). The rate of sustained response to antiviral therapy was twice as high in the CsA group, 50% versus 22% (P = 0.16; NS)., Conclusions: Graft survival in liver transplant recipients with HCV may be greater with CsA-based immunosuppression. There may also be a lower rate of fibrosing cholestatic hepatitis in this group.
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- 2006
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42. Discovery of 4-aryl-4H-chromenes as a new series of apoptosis inducers using a cell- and caspase-based high-throughput screening assay. 2. Structure-activity relationships of the 7- and 5-, 6-, 8-positions.
- Author
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Kemnitzer W, Kasibhatla S, Jiang S, Zhang H, Zhao J, Jia S, Xu L, Crogan-Grundy C, Denis R, Barriault N, Vaillancourt L, Charron S, Dodd J, Attardo G, Labrecque D, Lamothe S, Gourdeau H, Tseng B, Drewe J, and Cai SX
- Subjects
- Antineoplastic Agents pharmacology, Benzopyrans pharmacology, Caspases drug effects, Cell Line, Tumor, Cell Proliferation drug effects, Drug Evaluation, Preclinical methods, Enzyme Activation drug effects, Humans, Hydrophobic and Hydrophilic Interactions, Structure-Activity Relationship, Antineoplastic Agents chemical synthesis, Apoptosis drug effects, Benzopyrans chemical synthesis
- Abstract
As a continuation of our efforts to discover and develop the apoptosis inducing 4-aryl-4H-chromenes as novel anticancer agents, we explored the SAR of 4-aryl-4H-chromenes with modifications at the 7- and 5-, 6-, 8-positions. It was found that a small hydrophobic group, such as NMe2, NH2, NHEt, and OMe, is preferred at the 7-position. Di-substitution at either the 5,7-positions or the 6,7-positions generally led to a large decrease in potency. Di-substitution at the 7,8-positions, in general, was found to result in potent compounds. 7-NMe2, 7-NHEt, 7-OMe, and 7,8-di-NH2 analogs were found to have similar SAR for the 4-aryl group, and several 7-substituted and 7,8-di-substituted analogs were found to have similar potencies as the lead compound MX58151 (2a) both as caspase activators and inhibitors of cell proliferation.
- Published
- 2005
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43. Understanding barriers to continence care in institutions.
- Author
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Tannenbaum C, Labrecque D, and Lepage C
- Subjects
- Aged, Cross-Sectional Studies, Humans, Long-Term Care, Homes for the Aged, Nursing Homes, Urinary Incontinence therapy
- Abstract
This work seeks to identify factors that facilitate or diminish care-providers' propensity to improve continence care in long-term care (LTC) settings. We conducted a cross-sectional qualitative study using focus group methodology in four long-term care institutions in Montreal, QC. Forty-two nurses, nursing assistants, and orderlies caring for incontinent elderly residents were asked how they perceived urinary incontinence (UI), how it was being managed, and what factors enabled or hindered continence care in their institution. Content analysis was used. Facilitating and inhibiting elements of three individual/internal factors (beliefs about UI, attitudes towards the elderly, and knowledge about UI) and five institutional/external factors (workload demands, type of patient, environmental support, co-worker support, and attributes of UI interventions) emerged as important determinants of care-providers' propensity to manage UI. To be successful, continence programs must target multidimensional elements that take into account personal, systems, and organizational level factors.
- Published
- 2005
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- View/download PDF
44. Metallophilic interactions in closed-shell d10 metal-metal dicyanide bonded luminescent systems Eu[Ag(x)Au(1-x)(CN)2]3 and their tunability for excited state energy transfer.
- Author
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Colis JC, Staples R, Tripp C, Labrecque D, and Patterson H
- Subjects
- Energy Transfer, Luminescence, Models, Molecular, Sensitivity and Specificity, Spectrum Analysis, Raman, Cyanides chemistry, Europium chemistry, Gold chemistry, Silver chemistry
- Abstract
We report on the heterobimetallic system, Eu[Ag(x)Au(1-x)(CN)(2)](3) (x = 0-1) in which sensitization of europium luminescence occurs by energy transfer from [Ag(x)Au(1-x)(CN)(2)](-) donor excited states. The donor states have energies which are tunable and dependent on the Ag/Au stoichiometric ratio. These layered systems exhibit interesting properties, one of which is their emission energy tunability when excited at different excitation wavelengths. In this paper, we report on their use as donor systems with Eu(III) ions as acceptor ions in energy transfer studies. Luminescence results show that the mixed metal dicyanides with the higher silver loading have a better energy transfer efficiency than the pure Ag(CN)(2)(-) and Au(CN)(2)(-) donors. The better energy transfer efficiency is due to the greater overlap between the donor emission and acceptor excitation. Additionally, more acceptor states are available in the high silver loading mixed metal Eu(III) complexes. The results from a crystal structure determination and Raman experiments are also presented in this paper and provide information about metallophilic interactions in the closed-shell d(10) metal-metal [Ag(x)Au(1-x)(CN(2)](-) dicyanide clusters.
- Published
- 2005
- Full Text
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45. Antivascular and antitumor evaluation of 2-amino-4-(3-bromo-4,5-dimethoxy-phenyl)-3-cyano-4H-chromenes, a novel series of anticancer agents.
- Author
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Gourdeau H, Leblond L, Hamelin B, Desputeau C, Dong K, Kianicka I, Custeau D, Boudreau C, Geerts L, Cai SX, Drewe J, Labrecque D, Kasibhatla S, and Tseng B
- Subjects
- Amination, Angiogenesis Inhibitors blood, Angiogenesis Inhibitors chemistry, Angiogenesis Inhibitors pharmacokinetics, Animals, Antineoplastic Agents blood, Antineoplastic Agents chemistry, Antineoplastic Agents pharmacokinetics, Benzopyrans blood, Benzopyrans chemistry, Benzopyrans pharmacokinetics, Bromine chemistry, Cell Line, Tumor, Female, Humans, Male, Mice, Necrosis, Neoplasm Transplantation, Neoplasms drug therapy, Transplantation, Heterologous, Angiogenesis Inhibitors pharmacology, Antineoplastic Agents pharmacology, Benzopyrans pharmacology, Drug Screening Assays, Antitumor, Neoplasms blood supply, Neoplasms pathology, Neovascularization, Pathologic drug therapy
- Abstract
A novel series of 2-amino-4-(3-bromo-4,5-dimethoxy-phenyl)-3-cyano-4H-chromenes was identified as potent apoptosis inducers through a cell-based high throughput screening assay. Six compounds from this series, MX-58151, MX-58276, MX-76747, MX-116214, MX-116407, and MX-126303, were further profiled and shown to have potent in vitro cytotoxic activity toward proliferating cells only and to interact with tubulin at the colchicine-binding site, thereby inhibiting tubulin polymerization and leading to cell cycle arrest and apoptosis. Furthermore, these compounds were shown to disrupt newly formed capillary tubes in vitro at low nanomolar concentrations. These data suggested that the compounds might have vascular targeting activity. In this study, we have evaluated the ability of these compounds to disrupt tumor vasculature and to induce tumor necrosis. We investigated the pharmacokinetic and toxicity profiles of all six compounds and examined their ability to induce tumor necrosis. We next examined the antitumor efficacy of a subset of compounds in three different human solid tumor xenografts. In the human lung tumor xenograft (Calu-6), MX-116407 was highly active, producing tumor regressions in all 10 animals. Moreover, MX-116407 significantly enhanced the antitumor activity of cisplatin, resulting in 40% tumor-free animals at time of sacrifice. Our results identify MX-116407 as the lead candidate and strongly support its continued development as a novel anticancer agent for human use.
- Published
- 2004
46. Discovery of thiophene-2-carboxylic acids as potent inhibitors of HCV NS5B polymerase and HCV subgenomic RNA replication. Part 1: Sulfonamides.
- Author
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Chan L, Das SK, Reddy TJ, Poisson C, Proulx M, Pereira O, Courchesne M, Roy C, Wang W, Siddiqui A, Yannopoulos CG, Nguyen-Ba N, Labrecque D, Bethell R, Hamel M, Courtemanche-Asselin P, L'Heureux L, David M, Nicolas O, Brunette S, Bilimoria D, and Bédard J
- Subjects
- Carboxylic Acids, Carcinoma, Hepatocellular chemistry, Carcinoma, Hepatocellular enzymology, Carcinoma, Hepatocellular virology, Enzyme Inhibitors chemistry, Genome, Viral, Humans, Liver Neoplasms chemistry, Liver Neoplasms enzymology, Liver Neoplasms virology, RNA-Dependent RNA Polymerase antagonists & inhibitors, Replicon drug effects, Structure-Activity Relationship, Sulfonamides chemistry, Thiophenes chemistry, Virus Replication drug effects, Enzyme Inhibitors pharmacology, Hepacivirus enzymology, RNA, Viral metabolism, Sulfonamides pharmacology, Thiophenes pharmacology, Viral Nonstructural Proteins antagonists & inhibitors
- Abstract
The discovery of a novel class of HCV NS5B polymerase inhibitors, 3-arylsulfonylamino-5-phenyl-thiophene-2-carboxylic acids is described. SAR studies have yielded several potent inhibitors of HCV polymerase as well as of HCV subgenomic RNA replication in Huh-7 cells.
- Published
- 2004
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47. Liver regeneration investigated in a non-human primate model (Macaca mulatta).
- Author
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Gaglio PJ, Liu H, Dash S, Cheng S, Dunne B, Ratterree M, Baskin G, Blanchard J, Bohm R Jr, Theise ND, and LaBrecque D
- Subjects
- Animals, Blotting, Southern, Cell Division physiology, Gene Expression physiology, Hepatectomy, Hepatocyte Growth Factor genetics, Interleukin-6 genetics, Ki-67 Antigen analysis, Liver chemistry, Liver cytology, Male, Mitosis physiology, Pilot Projects, Proliferating Cell Nuclear Antigen analysis, Reverse Transcriptase Polymerase Chain Reaction, Transforming Growth Factor alpha genetics, Transforming Growth Factor beta genetics, Tumor Necrosis Factor-alpha genetics, Liver physiology, Liver Regeneration physiology, Macaca mulatta, Models, Animal
- Abstract
Background/aims: An adequate model to study liver regeneration in humans is presently unavailable. We explored the feasibility of studying liver regeneration in a genetically similar species to man, the non-human primate Rhesus macaque., Methods: Five animals were studied; two underwent 60% hepatectomy, one underwent 30% hepatectomy, and cholecystectomy alone was performed on two animals. Laparoscopic-guided or open liver biopsies were performed on days 1, 2, 7, 14, 21, 30 and 60 following all surgeries. Liver regeneration was evaluated by measuring Ki-67, proliferating cell nuclear antigen expression and mitotic index, calculating changes in the surface area of the liver remnant and assessing intrahepatic production of cytokines., Results: Significant liver regeneration was induced in the animals that underwent 60% hepatectomy, peaking between days 21-30 postoperatively. Regeneration was minimal in all other animals studied. Cytokine production followed a similar pattern. Maximal liver regeneration correlated with restoration of surface area in the liver remnant., Conclusions: Sixty percent hepatectomy in a non-human primate model induced significant liver regeneration, maximizing 21-30 days following partial hepatectomy, suggesting a significant interspecies difference when compared to a rodent hepatectomy model. A partial hepatectomy model in Rhesus macaques may allow further characterization of liver regeneration in a species closer to humans., (Copyright 2002 European Association for the Study of the Liver)
- Published
- 2002
- Full Text
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48. Suprahepatic venacavaplasty (cavaplasty) with retrohepatic cava extension in liver transplantation: experience with first 115 cases.
- Author
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Wu YM, Voigt M, Rayhill S, Katz D, Chenhsu RY, Schmidt W, Miller R, Mitros F, and Labrecque D
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Female, Hepatectomy, Humans, Liver Transplantation adverse effects, Male, Middle Aged, Retrospective Studies, Liver Transplantation methods, Venae Cavae surgery
- Abstract
Background: We first introduced the orthotopic liver transplantation utilizing cavaplasty technique in 1994. This paper describes the surgical technique and assesses the outcome of the cavaplasty OLT., Methods: The cavaplasty procedure was used in 115 consecutive orthotopic liver transplantations, including six left lateral and two right lobe transplantations, between November 1994 and September 2000. Fifty-three (66.3%) transplantations required femoro-axillary veno-venous bypass in the initial 4 years, whereas only eight (22.9%) needed VB in the subsequent 2 years. Conversion to piggyback or standard technique was not necessary in any patient., Results: Median results are as follows: operative time 4.5 hr, warm ischemia time 25 min, and blood transfused (packed red blood cells) 6 units. These findings did not differ between first transplantation and retransplantation. There were no perioperative deaths related to the cavaplasty technique. No hepatic venous outflow obstruction was observed, including living-related OLTs. No patient required postoperative hemodialysis for acute renal failure. The median intensive care and hospital stays were 2 days and 10 days, respectively., Conclusions: The cavaplasty technique requires no retrocaval, hepatic vein, or short hepatic vein dissection, and the inferior vena cava can be preserved, which provides advantages for hepatectomy and easy hemostasis, especially during retransplantation. The wide-open triangular caval anastomosis is easy to perform, allowing short implantation time and size matching and avoiding outflow obstruction. The short implantation time reduces the need for veno-venous bypass. Our experience indicates that the cavaplasty technique can be applied to all patients and is justified by minimal technical complications.
- Published
- 2001
- Full Text
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49. A model to examine the validity of the 6-month abstinence criterion for liver transplantation.
- Author
-
Yates WR, Martin M, LaBrecque D, Hillebrand D, Voigt M, and Pfab D
- Subjects
- Adult, Eligibility Determination, Female, Humans, Male, Middle Aged, Personality Assessment statistics & numerical data, Psychometrics, Recurrence, Reproducibility of Results, Time Factors, Treatment Outcome, Alcoholism rehabilitation, Liver Cirrhosis, Alcoholic rehabilitation, Liver Transplantation, Temperance
- Abstract
Six months of abstinence from alcohol is a commonly used criterion for liver transplantation eligibility for patients with alcoholic cirrhosis. There is limited evidence to document the validity of this criterion with regard to risk of alcoholism relapse. Ninety-one patients with alcoholic cirrhosis were interviewed for relapse risk using the High Risk Alcoholism Relapse (HRAR) Scale. The HRAR model can be used to predict relapse risk independent of duration of sobriety and therefore can be used to examine the validity of the 6 months of abstinence criteria in this clinical population. The two methods demonstrated poor to fair agreement. Agreement was highest with a cutoff allowing a 5% 6-month relapse risk when 79% agreement (c = 0.56) was demonstrated between the two methods. Using the 6-month abstinence criterion alone disallows a significant number of candidates who have a low relapse risk based on their HRAR score. The validity of the 6-month abstinence criterion is supported somewhat by comparison with the HRAR model. However, use of the 6-month abstinence criterion alone forces a significant number of patients with a low relapse risk by HRAR to wait for transplant listing. A relapse risk model based on an estimate of alcoholism severity in addition to duration of sobriety may more accurately select patients who are most likely to benefit from liver transplantation.
- Published
- 1998
50. Transplantation of patients with alcoholic liver disease.
- Author
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Gerdes T, Yates W, Martin M, and LaBrecque D
- Subjects
- Humans, Iowa, Recurrence, Risk Factors, United States, Health Care Rationing, Liver Diseases, Alcoholic surgery, Liver Transplantation
- Published
- 1994
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