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Vos S, Sandler LA, Chavez R. Help! Accommodating learners with disabilities during practice‐based activities. J Am Coll Clin Pharm 2021. [DOI: 10.1002/jac5.1431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Susan Vos
- The University of Iowa College of Pharmacy Iowa City Iowa USA
| | | | - Raemi Chavez
- The University of Iowa College of Pharmacy Iowa City Iowa USA
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Biehle L, Crowl A, Park HC, Vos S, Franks AM. The Power of Peer Mentoring to Support Women Pharmacy Faculty Personally and Professionally. Am J Pharm Educ 2021; 85:8471. [PMID: 34283744 PMCID: PMC7926275 DOI: 10.5688/ajpe8471] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 11/17/2020] [Indexed: 05/22/2023]
Abstract
Regardless of a faculty member's career stage, effective mentoring is critical for successful professional development and a thriving academic career. Traditional mentor-mentee relationships can be effective but may present challenges for some faculty depending on their individual needs and institutional resources. The use of peer mentoring circles, where group members serve as both mentor and mentee, may provide additional resources and benefits to faculty at all career stages and appear especially beneficial for women faculty because of their focus on interconnectedness and collaboration. However, literature is scarce regarding effective mentoring strategies for women pharmacy faculty. As members of one women faculty-only peer mentoring circle, we describe our experiences using this mentoring strategy and offer recommendations for other faculty members considering this approach.
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Affiliation(s)
- Lauren Biehle
- University of Wyoming School of Pharmacy, Laramie, Wyoming
| | - Ashley Crowl
- University of Kansas School of Pharmacy, Lawrence, Kansas
| | - Helen C Park
- Roseman University of Health Sciences, Henderson, Nevada
| | - Susan Vos
- The University of Iowa College of Pharmacy, Iowa City, Iowa
| | - Amy M Franks
- University of Arkansas for Medical Sciences College of Pharmacy, Little Rock, Arkansas
- Editorial Board Member, American Journal of Pharmaceutical Education, Arlington, Virginia
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O'Sullivan TA, Cox CD, Darbishire P, Dinkins MM, Johanson EL, Joseph A, Vos S. The Status and Adequacy of Preceptor Orientation and Development Programs in US Pharmacy Schools. Am J Pharm Educ 2020; 84:7540. [PMID: 32226070 PMCID: PMC7092789 DOI: 10.5688/ajpe7540] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 08/07/2019] [Indexed: 05/22/2023]
Abstract
Objective. To identify current preceptor orientation and development programs at US colleges and schools of pharmacy and propose future initiatives for preceptor programs. Methods. An anonymous 28-item survey was administered in January 2017 to 128 experiential education personnel at accredited US schools and colleges of pharmacy. Data from completed survey instruments were tabulated and qualitative responses to open-ended questions were examined using thematic analysis. Results. Eighty-five experiential education administrators participated in the survey (response rate=67%). Most preceptor orientation programs met the majority of requirements as outlined within the Accreditation Council for Pharmacy Education's Standard 20.3, although only 42% of programs mandated preceptor orientation prior to student placement. Two-thirds of respondents offered annual, live preceptor development, and 75% of programs used commercially available online products. Nearly 40% of respondents collaborated with other schools or professional organizations to offer preceptor training. Only 29% of programs had specific requirements for pharmacists to maintain their active preceptor status. Seventy percent of respondents reported spending over $2500 and 39% over $5000 annually on preceptor development. Programs with the highest monetary investment (>$10,000/year) in preceptor development offered multiple venues (live and online) for preceptor training. Programs with significant personnel commitment (≥0.5 FTE devoted to preceptor development) frequently had dedicated site visitors. Conclusion. Preceptor orientation programs at US schools of pharmacy are generally similar, but development programs vary significantly across the Academy. Highly invested programs featured live and online training or site visitors who provided individualized feedback or training. Future studies should explore the cost-effectiveness of program options and their impact on preceptor learning and behaviors.
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Affiliation(s)
| | - Craig D Cox
- Texas Tech University Health Sciences Center Jerry H Hodge School of Pharmacy, Lubbock, Texas
| | - Patricia Darbishire
- Purdue University College of Pharmacy, West Lafayette, Indiana
- Editorial Board Member, American Journal of Pharmaceutical Education, Arlington, Virginia
| | | | - Erin L Johanson
- Roseman University of Health Sciences, College of Pharmacy, South Jordan, Utah
| | - Andrea Joseph
- Thomas Jefferson University, Jefferson College of Pharmacy, Philadelphia, Pennsylvania
| | - Susan Vos
- The University of Iowa College of Pharmacy, Iowa City, Iowa
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Vos S, Kooyman C, Feudo D, Goliak KL, Kieser M, Legg J, Parent-Stevens L, Walker PC, Rodriguez R. When Experiential Education Intersects with Learning Disabilities. Am J Pharm Educ 2019; 83:7468. [PMID: 31831910 PMCID: PMC6900816 DOI: 10.5688/ajpe7468] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Affiliation(s)
- Susan Vos
- The University of Iowa College of Pharmacy, Iowa City, Iowa
| | - Chase Kooyman
- The University of Iowa College of Pharmacy, Iowa City, Iowa
| | - Donna Feudo
- Rutgers Ernst Mario School of Pharmacy, Piscataway, New Jersey
| | - Kristen L Goliak
- University of Illinois at Chicago, College of Pharmacy, Chicago, Illinois
| | - Mara Kieser
- University of Wisconsin School of Pharmacy, Madison, Wisconsin
| | - Julie Legg
- The Ohio State University, Columbus, Ohio
| | | | - Paul C Walker
- University of Michigan College of Pharmacy, Ann Arbor, Michigan
| | - Raquel Rodriguez
- University of Minnesota College of Pharmacy, Minneapolis, Minneapolis
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Boen F, Pelssers J, Scheerder J, Vanbeselaere N, Vos S, Hurkmans E, Smits T, Fransen K. Does Social Capital Benefit Older Adults' Health and Well-Being? The Mediating Role of Physical Activity. J Aging Health 2019; 32:688-697. [PMID: 31092109 DOI: 10.1177/0898264319848638] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objectives: To assess whether social capital benefits older adults' self-rated health and well-being and whether physical activity mediates this relation. Methods: A survey study was conducted among members of a sociocultural organization (age ≥55 years), both cross-sectionally (baseline Time 1; N = 959) and longitudinally (3-year follow-up Time 2; N = 409). Results: Specific indicators of social capital were positively, though modestly, related to health and well-being at Time 1 and Time 2. Experienced connectedness with age peers emerged as the strongest predictor. Physical activity only mediated the relation with experienced safety in society. Discussion: The relative importance of older adults' experienced connectedness with their age peers underlines the importance of internalized group membership as a determinant of their health and well-being. Physical activity seems to play only a minor mediating role.
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Affiliation(s)
- F Boen
- KU Leuven, Leuven, Belgium
| | | | | | | | - S Vos
- KU Leuven, Leuven, Belgium.,Fontys University of Applied Sciences, Eindhoven, The Netherlands.,Eindhoven University of Technology, Eindhoven, The Netherlands
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Sparks R, Vakharia V, Rodionov R, Vos S, McEvoy A, Miserocchi A, Duncan J, Ourselin S. P35 Ability to quantify stereoelectroencephalography (SEEG) electrode trajectory proximity to vessels across imaging protocols. J Neurol Psychiatry 2019. [DOI: 10.1136/jnnp-2019-abn.107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
ObjectivesAutomated planning of stereoelectroencephalography (SEEG) electrode trajectories is dependent on vessel segmentation.1 We quantify imaging protocols ability to measure trajectory-to-vessel distance.DesignRetrospective analysis.SubjectsTen consecutive patients were selected whom had SEEG implantation (95 electrodes) and Digital Catheter Subtraction Angiography (DSA) with catheterization of carotid or vertebral arteries, post-gadolinium T1-weighted (GAD), phase-contrast MR angiography and MR venography (MR) acquired.MethodsSEEG trajectories were planned manually with DSA. Minimum distance to vessels and risk1 were computed for each trajectory using vessel segmentation from GAD, MR, or DSA. Vessel size was considered by including DSA vessels diameters above 1, 2, 3, or 4 mm.ResultsMinimum distance to a vessel was 6.2±3.9 mm (GAD), 2.5±1.6 mm (MR), and 1.5±1.2 mm (DSA). Based on DSA vessel size minimum distances were 2.0±1.5 mm (DSA >1 mm), 3.4±2.6 (DSA >2 mm), 6.6±4.6 mm (DSA >3 mm), and 11.8±7.9 mm (DSA >4 mm). Risk was 0.4±0.4 (GAD), 0.8±0.4 (MR), and 1.1±0.2 (all DSA), 1.0±0.2 (DSA >1 mm), 0.7±0.4 (DSA >2 mm), 0.4±0.5 (DSA >3 mm), and 0.2±0.3 (DSA >4 mm).ConclusionsDSA is best able to segment vessels. MR has metrics similar to DSA vessels above 2 mm. GAD has metrics similar to DSA vessels above 3 mm.
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Kuiper JWP, Vos S, Burger TJ, Colen S. Variety in diagnosis and treatment of periprosthetic joint infections in Belgium and the Netherlands. Acta Orthop Belg 2016; 82:149-160. [PMID: 27682274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recently, guidelines regarding diagnosis and treatment of periprosthetic joint infection (PJI) have been published, but it is unknown how well these are -followed in the Netherlands and Belgium. Therefore, a survey study was performed in the Netherlands and Belgium. 81 orthopedic departments responded (54% in the Netherlands, 52% in Belgium). The majority used protocols for antibiotic and surgical treatment. To discriminate between early and late infection, differences in periods used were seen between respondents, and between countries. Empirical antibiotic treatment varied greatly. Debridement, antibiotics, irrigation and retention of the prosthesis (DAIR) is the -almost unanimous treatment of choice for early PJI. Guidelines are available, but seem not (yet) to be -followed accurately, and do not have answers to all possible treatment options. Perhaps, national guidelines might produce more standardized care, and -consequentially, easier comparison for research, more transparency for patients, and less health care costs.
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Fransen B, Hoozemans M, Vos S. Direct anterior approach versus posterolateral approach in total hip arthroplasty : one surgeon, two approaches. Acta Orthop Belg 2016; 82:240-248. [PMID: 27831458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Early research shows several advantages of the Direct Anterior Approach (DAA) in total hip arthroplasty (THA), although no studies evaluated the DAA on a regular operating table without using fluoroscopy. We performed a retrospective cohort study on the outcome of this variation of the DAA compared with the posterolateral approach (PLA) with one year follow-up. All procedures were uncemented THA performed in 2012 by a single surgeon. Patients in the DAA group (N = 45) had a lower Body Mass Index (p > .001) than the PLA group (N = 38). Functional outcome, pain scores and complications were comparable between the two approaches. Compared with PLA, the DAA was associated with longer operation time (p > 0.001), more blood loss (p > 0.001), shorter length of stay (p = .009), and more adequate acetabular cup inclination (p = .004). This study shows that the DAA on a regular operating table without using fluoroscopy has several advantages compared to the PLA.
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Jeger MJ, Pautasso M, Stancanelli G, Vos S. The EFSA assessment ofTrichilogaster acaciaelongifoliaeas biocontrol agent of the invasive alien plantAcacia longifolia: a new area of activity for the EFSA Plant Health Panel? ACTA ACUST UNITED AC 2016. [DOI: 10.1111/epp.12306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. J. Jeger
- Centre for Environmental Policy; Imperial College London; London UK
| | - M. Pautasso
- Animal and Plant Health Unit; European Food Safety Authority (EFSA); Parma Italy
| | - G. Stancanelli
- Animal and Plant Health Unit; European Food Safety Authority (EFSA); Parma Italy
| | - S. Vos
- Animal and Plant Health Unit; European Food Safety Authority (EFSA); Parma Italy
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Vos S, van der Wall E, van Diest PJ, van der Groep P. Abstract P5-01-06: Differences in FGF1 and FGFR2 expression in BRCA1-associated, BRCA2-associated, and sporadic breast carcinomas. Cancer Res 2012. [DOI: 10.1158/0008-5472.sabcs12-p5-01-06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Introduction. In contrast to BRCA1-associated breast cancer, a distinctive phenotype for BRCA2-associated carcinomas has not been identified yet as there is no clear distinction between BRCA2- and non-BRCA mutation related or sporadic carcinomas. Recently, studies suggest overexpression of fibroblast growth factor 1 (FGF1) and fibroblast growth factor receptor 2 (FGFR2) in BRCA2 related cancers. The aim of the study was therefore to investigate whether there is differential expression of FGF1 and/or FGFR2 between BRCA2 related and sporadic and BRCA1 related cancers. This would reveal the usefulness of FGF1 and FGFR2 immunohistochemistry in daily pathology practise.
Method. Invasive breast carcinomas of 33 BRCA1 and 22 BRCA2 germline mutation carriers and a tissue microarray containing 104 sporadic invasive breast carcinomas were immunohistochemically stained for FGF1, FGFR2, estrogen receptor (ER), progesterone receptor (PR), HER2, epidermal growth factor receptor 1 (EGFR), cytokeratin (CK) 5/6 and CK14.
Results. FGFR2 expression was seen in 68.2% and 79.0% of BRCA2-associated and sporadic carcinomas respectively, in contrast to 22.6% of BRCA1-associated tumors (p = 0.000). FGF1 expression was seen in 72.7% of BRCA2-associated carcinomas and in 45.2% and 41.8% in BRCA1-associated and sporadic carcinomas, respectively (p = 0.032).
Conclusion. FGFR2 expression differs significantly between BRCA1- and BRCA2 associated breast carcinomas but not between BRCA2 and sporadic cancers. FGF1 expression differs significantly between BRCA2-associated and sporadic carcinomas and could be used as a BRCA2-specific biomarker.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-01-06.
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Affiliation(s)
- S Vos
- University Medical Center Utrecht, Netherlands
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Mormann M, Gilbertson C, Milavetz G, Vos S. Dispelling vaccine myths: MMR and considerations for practicing pharmacists. J Am Pharm Assoc (2003) 2012; 52:e282-6. [DOI: 10.1331/japha.2012.11239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Jansen R, Vos S, Cleophas TJ, Niemeijer MG, Zwinderman AH, Buunk B. Quality of life with heart failure: psychosocial determinants to be considered by cardiologists. Neth Heart J 2003; 11:337-340. [PMID: 25696242 PMCID: PMC2499946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
BACKGROUND Independent determinants of QOL (quality of life) with heart disease have been recognised and include factors such as severity of medical condition, comorbidity, and concomitant medication. Psychosocial factors, as 'ability to cope with the unpleasantness of the medical condition', 'want of information', and 'social identification' have an important influence on self-perceived wellbeing, but their influence on health-related QOL domains and self-perceived QOL in patients with heart failure has not been systematically studied. OBJECTIVE To assess correlation between such psychosocial factors and QOL in patients with heart failure. METHODS Patients from the outpatient heart failure clinic of the Martini Hospital, a 1000-bed community hospital in the city of Groningen, the Netherlands, were included if their ejection fractions were <40% and their medical diagnosis according to their cardiologists was stable chronic congestive heart failure. The following QOL estimators were applied: Pearlin's Mastery Scale, Stewart's Short Form 36 Quality of Life Questionnaire, Dupuy's Index of Wellbeing, Cantrill's Self-perceived Quality of Life Scale, Mester's Want of Information Scale. Internal consistency of the multi-item scales was estimated by Cronbach's alphas. Linear and multiple linear regression analyses were performed of the data. RESULTS Sixty patients were enrolled, 41 males and 19 females, average age 68 years (range 51 to 84 years). 'Ability to cope with the unpleasantness of the medical condition' was not only an independent determinant of self-perceived and health-related QOL (both p<0.001), but also of each domain of health-related QOL separately (p<0.001 for each domain). Lack of 'adequate medical information' and 'negative social identification' (identification with fellow-sufferers who are doing worse) were negative predictors of 'ability to cope' (p<0.01 and <0.001 respectively). 'Negative social identification' was also an independent determinant of self-perceived QOL, both unadjusted and after adjustment for 'ability to cope' and 'adequate medical information'. CONCLUSION Relevant recommendations from this paper to be considered by cardiologists during everyday office hours could include: 1. Patients who express having difficulties in coping with the unpleasant aspects of their underlying heart condition have low health-related QOL as well as low self-perceived QOL. 2. Providing adequate medical information is a significant contributor to both better 'ability to cope' and better self-perceived QOL. 3. Avoiding identifying with fellow-sufferers who are doing worse and, instead, starting to identify with those who are doing better, are significant contributors to both better 'ability to cope' and better self-perceived QOL.
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Abstract
Baccatin III is widely considered to be an inactive derivative of Taxol. We have reexamined its effect on in vitro assembly of tubulin under a variety of conditions. We found baccatin III to be active in all circumstances in which Taxol is active: it assembled GTP-tubulin, GDP-tubulin, and microtubule protein into normal microtubules and stabilized these polymers against cold-induced disassembly. The effect of baccatin III on in vitro microtubule assembly was quantitatively assessed through determination of critical concentrations, which can be used to obtain the apparent equilibrium constants for the addition of tubulin subunits to growing microtubules. The apparent equilibrium constants for the growth reaction for baccatin III-induced GTP-tubulin and GDP-tubulin assembly measured at 37 degrees C were 4.2-4.6-fold less than those measured for Taxol-induced GTP-tubulin and GDP-tubulin assembly. These data indicate that the entire Taxol side chain contributes only about -1 kcal/mol to the apparent standard free energy of microtubule growth at 37 degrees C regardless of the nature of the E site nucleotide. These data also support the idea that the majority of the interactions between Taxol and tubulin that affect this equilibrium occur between the baccatin portion of the molecule and the binding site. We have also observed a structural difference in microtubules formed using baccatin III and Taxol. Baccatin III-induced microtubules were routinely much longer than those assembled by Taxol, even when very high concentrations of baccatin III were employed. One interpretation of these data is that baccatin III and Taxol differ in their abilities to nucleate GTP-tubulin. This difference in activity may have bearing on the large disparity in cytotoxicity of the two molecules.
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Affiliation(s)
- S K Chatterjee
- Department of Chemistry, State University of New York, Binghamton, New York 13902-6016, USA
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Vos S, Parry RJ, Burns MR, de Jersey J, Martin JL. Structures of free and complexed forms of Escherichia coli xanthine-guanine phosphoribosyltransferase. J Mol Biol 1998; 282:875-89. [PMID: 9743633 DOI: 10.1006/jmbi.1998.2051] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Structures of free, substrate-bound and product-bound forms of Escherichia coli xanthine-guanine phosphoribosyltransferase (XGPRT) have been determined by X-ray crystallography. These are compared with the previously determined structure of magnesium and sulphate-bound XPRT. The structure of free XGPRT at 2.25 A resolution confirms the flexibility of residues in and around a mobile loop identified in other PRTases and shows that the cis-peptide conformation of Arg37 at the active site is maintained in the absence of bound ligands. The structures of XGPRT complexed with the purine base substrates guanine or xanthine in combination with cPRib-PP, an analog of the second substrate PRib-PP, have been solved to 2.0 A resolution. In these two structures the disordered phosphate-binding loop of uncomplexed XGPRT becomes ordered through interactions with the 5'-phosphate group of cPRib-PP. The cyclopentane ring of cPRib-PP has the C3 exo pucker conformation, stabilised by the cPRib-PP-bound Mg2+. The purine base specificity of XGPRT appears to be due to water-mediated interactions between the 2-exocyclic groups of guanine or xanthine and side-chains of Glu136 and Asp140, as well as the main-chain oxygen atom of Ile135. Asp92, together with Lys115, could help stabilise the N7-protonated tautomer of the incoming base and could act as a general base to remove the proton from N7 when the nucleotide product is formed. The 2.6 A resolution structure of XGPRT complexed with product GMP is similar to the substrate-bound complexes. However, the ribose ring of GMP is rotated by approximately 24 degrees compared with the equivalent ring in cPRib-PP. This rotation results in the loss of all interactions between the ribosyl group and the enzyme in the product complex.
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Affiliation(s)
- S Vos
- Department of Biochemistry, The University of Queensland, Brisbane, Qld 4072, Australia
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Abstract
Individuals with schizophrenia have a high prevalence of smoking compared with the general population and little is known about why so many people with schizophrenia smoke. This paper reviews suggestions of differences in motivation for smoking. Possible explanations for smoking include psychological reasons, together with possible effects on positive and negative symptoms of schizophrenia and reduced side-effects of neuroleptics. Understanding complex issues related to smoking and schizophrenia is important prior to developing health promotion strategies.
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Affiliation(s)
- C Forchuk
- London Health Sciences Centre, Research Institute, Ontario, Canada
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Abstract
Xanthine phosphoribosyltransferase (XPRT; EC 2.4.2.22) from Escherichia coli is a tetrameric enzyme having 152 residues per subunit. XPRT catalyzes the transfer of the phosphoribosyl group from 5-phospho-alpha-D-ribosyl 1-pyrophosphate (PRib-PP) to the 6-oxopurine bases guanine, xanthine, and hypoxanthine to form GMP, XMP, and IMP, respectively. Crystals grown in the absence of substrate or product were used to determine the structure of XPRT at a resolution of 1.8 A, by multiple isomorphous replacement. The core structure of XPRT includes a five-stranded parallel beta-sheet surrounded by three alpha-helices, which is similar to that observed in other known phosphoribosyltransferase (PRTase) structures. The XPRT structure also has several interesting features. A glutamine residue in the purine binding site may be responsible for the altered 6-oxopurine base specificity seen in this enzyme compared to other 6-oxopurine PRTases. Also, we observe both a magnesium ion and a sulfate ion bound at the PRib-PP binding site of XPRT. The sulfate ion interacts with Arg-37 which has a cis-peptide conformation, and the magnesium ion interacts with Asp-89, a highly conserved acidic residue in the PRib-PP binding site motif. The XPRT structure also incorporates a feature which has not been observed in other PRTase structures. The C-terminal 12 residues of XPRT adopt an unusual extended conformation and make interactions with a neighboring subunit. The very last residue, Arg-152, could form part of the active site of a symmetry-related subunit in the XPRT tetramer.
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Affiliation(s)
- S Vos
- Department of Biochemistry, The University of Queensland, Brisbane, Australia
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Vos S, de Jersey J, Martin JL. Crystallization and preliminary X-ray crystallographic studies of Escherichia coli xanthine phosphoribosyltransferase. J Struct Biol 1996; 116:330-4. [PMID: 8812991 DOI: 10.1006/jsbi.1996.0050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Xanthine phosphoribosyltransferase (XPRT; EC 2.4.2.22) from Escherichia coli is a purine salvage enzyme which synthesizes the nucleotides GMP, XMP, and IMP. A mutant C59A, which is more stable than wild-type XPRT while retaining high activity, has been prepared and crystallized to give three different crystal forms (A, B, and C). Form A crystals are orthorhombic (P21212), with unit cell dimensions a = 59.2 A, b = 92.9 A, c = 53.2 A. Form B crystals are monoclinic (C2) with unit cell dimensions a = 84.4 A, b = 70.8 A, c = 54.1 A, and beta = 113.4 degrees, and form C crystals are tetragonal (P41212 or P43212) with unit cell dimensions a,b = 94 A, c = 167.5 A. Wild-type XPRT and a selenomethionine derivative of C59A XPRT have also been crystallized in the orthorhombic form. The selenomethionine derivative was prepared by expressing XPRT in the usual E. coli strain without the need for a methionine auxotroph. Cells were grown in a methionine-deficient medium supplemented with selenomethionine which gave >95% incorporation. Both the wild-type and selenomethionine C59A XPRT crystals are isomorphous with C59A form A crystals.
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Affiliation(s)
- S Vos
- Centre for Protein Structure, Function and Engineering, University of Queensland, Australia
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