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537 citation(s) found for "Walker, J C".

H alomonas sulfidaeris ‐dominated microbial community inhabits a 1.8 km‐deep subsurface C ambria
Dong, Yiran , Kumar, Charu G., Kim, Pan‐Jun , Miller, P., Price, Nathan D. , Flynn, Theodore M. , Sanford, Robert A. , Krapac, Ivan G., Locke, Randall A. , Hong, Pei‐Ying , Tamaki, Hideyuki , Mackie, Roderick I. , Hernandez, Alvaro G. , Wright, Chris , Mikel, Mark A. , Walker, Jared, Sivaguru, Mayandi , Fried, Glenn , Yannarell, Anthony C. , Fouke, Bruce W. , Chia, Nicholas , Cann, Isaac , Liu, Wen‐Tso , Price, Nathan D

Environmental Microbiology | November 14, 2013 | Volume: 16 | Issue: 6 | Pages: 1695-1708

10.1111/1462-2920.12325 | PMID 24238218 Get It

Summary A low‐diversity microbial community, dominated by the γ ‐proteobacterium H alomonas sulfidaeris , was detected in samples of warm saline formation porewater collected from the C ambrian Mt. S imon S andstone in the I llinois B asin of the N orth A merican M idcontinent (1.8 km/5872 ft burial depth, 50° C , pH 8, 181 bars pressure). These highly porous and permeable quartz arenite sandstones are directly analogous to reservoirs around the world targeted for large‐scale hydrocarbon extraction, as well as subsurface gas and carbon storage. A new downhole low‐contamination subsurface sampling probe was used to collect in situ formation water samples for microbial environmental metagenomic analyses. Multiple lines of evidence suggest that this H . sulfidaeris ‐dominated subsurface microbial community is indigenous and not derived from drilling mud microbial contamination. Data to support this includes V 1‐ V 3 pyrosequencing of formation water and drilling mud, as well as comparison with previously published microbial analyses of drilling muds in other sites. Metabolic pathway reconstruction, constrained by the geology, geochemistry and present‐day environmental conditions of the Mt . S imon S andstone, implies that H . sulfidaeris ‐dominated subsurface microbial community may utilize iron and nitrogen metabolisms and extensively recycle indigenous nutrients and substrates. The presence of aromatic compound metabolic pathways suggests this microbial community can readily adapt to and survive subsurface hydrocarbon migration.
Comparison of mRNA Splicing Assay Protocols across Multiple Laboratories: Recommendations for Best Practice in Standardized Clinical Testing
Whiley, Phillip J , Hoya, Miguel de la , Thomassen, Mads , Becker, Alexandra, Pedersen, Inge Søkilde , Montagna, Marco , Menéndez, Mireia , Quiles, Francisco, Gutiérrez‐Enríquez, Sara , Leeneer, Kim De , Tenés, Anna, Montalban, Gemma , Tserpelis, Demis, Yoshimatsu, Toshio F. , Tirapo, Carole, Raponi, Michela , Caldés, Trinidad , Blanco, Ana , Guidugli, Lucia, Garibay, Gorka Ruíz de , Wong, Ming, Tancredi, Mariella, Fachal, Laura , Ding, Yuan Chun , Kruse, Torben A., Lattimore, Vanessa , Kwong, Ava , Chan, Tsun Leung , Colombo, Mara , Vecchi, Giovanni De, Caligo, Maria A. , Baralle, Diana , Lázaro, Conxi , Radice, Paolo , Southey, Melissa C. , Houdayer, Claude , Fackenthal, Jim, Hansen, Thomas van Overeem , Vega, Ana , Dı́ez, Orland , Blok, Rien, Claes, Kathleen , Wappenschmidt, Barbara , Walker, Logan C. , Spurdle, Amanda B. , Brown, Melissa A. , Brandão, Rita D. , Santamariña, Marta , Couch, Fergus J. , Neuhausen, Susan L. , Caligo, Maria A , Spurdle, Amanda B , Vega, Ana , de la Hoya, Miguel , Diez, Orland , Gutiérrez-Enríquez, Sara , Radice, Paolo , Claes, Kathleen B M , Southey, Melissa C , Lazaro, Conxi , Montagna, Marco , Ruiz de Garibay, Gorka , Montalban, Gemma , De Leeneer, Kim , Hansen, Thomas van Overeem , Kwong, Ava , Fachal, Laura

Clinical Chemistry | November 8, 2013 | Volume: 60 | Issue: 2 | Pages: 341-352

10.1373/clinchem.2013.210658 | PMID 24212087 Get It

Abstract BACKGROUND Accurate evaluation of unclassified sequence variants in cancer predisposition genes is essential for clinical management and depends on a multifactorial analysis of clinical, genetic, pathologic, and bioinformatic variables and assays of transcript length and abundance. The integrity of assay data in turn relies on appropriate assay design, interpretation, and reporting. METHODS We conducted a multicenter investigation to compare mRNA splicing assay protocols used by members of the ENIGMA (Evidence-Based Network for the Interpretation of Germline Mutant Alleles) consortium. We compared similarities and differences in results derived from analysis of a panel of breast cancer 1, early onset (BRCA1) and breast cancer 2, early onset (BRCA2) gene variants known to alter splicing (BRCA1: c.135-1G>T, c.591C>T, c.594-2A>C, c.671-2A>G, and c.5467+5G>C and BRCA2: c.426-12_8delGTTTT, c.7988A>T, c.8632+1G>A, and c.9501+3A>T). Differences in protocols were then assessed to determine which elements were critical in reliable assay design. RESULTS PCR primer design strategies, PCR conditions, and product detection methods, combined with a prior knowledge of expected alternative transcripts, were the key factors for accurate splicing assay results. For example, because of the position of primers and PCR extension times, several isoforms associated with BRCA1, c.594-2A>C and c.671-2A>G, were not detected by many sites. Variation was most evident for the detection of low-abundance transcripts (e.g., BRCA2 c.8632+1G>A Δ19,20 and BRCA1 c.135-1G>T Δ5q and Δ3). Detection of low-abundance transcripts was sometimes addressed by using more analytically sensitive detection methods (e.g., BRCA2 c.426-12_8delGTTTT ins18bp). CONCLUSIONS We provide recommendations for best practice and raise key issues to consider when designing mRNA assays for evaluation of unclassified sequence variants.
Cardiovascular Implantable Electronic Device Infections in Left Ventricular Assist Device Recipients
Riaz, Talha , Nienaber, Juhsien J. C., Walker, Randall C., Park, Soon J., Sohail, M. Rizwan , Baddour, Larry M. , Sohail, M Rizwan

Pacing and Clinical Electrophysiology | September 2, 2013 | Volume: 37 | Issue: 2 | Pages: 225-230

10.1111/pace.12240 | PMID 23998684 Get It

BackgroundMost patients with left ventricular assist devices (LVADs) have concomitant cardiovascular implantable electronic devices (CIEDs). However, clinical presentation and outcome of CIED infection in the setting of LVAD has not been previously described.MethodsWe retrospectively reviewed 247 patients who underwent LVAD implantation at Mayo Clinic campuses in Minnesota, Arizona, and Florida, from January 2005 to December 2011. Demographic and clinical data of patients who met criteria for CIED infection were extracted.ResultsOf 247 patients with LVADs, 215 (87%) had CIED at the time of LVAD implantation and six (2.8%) subsequently developed CIED infections. Three patients developed CIED lead‐related endocarditis and the other three had pocket infection. All three instances of CIED pocket infection were preceded by device generator exchange, whereas all three patients with CIED lead‐related endocarditis had prior LVAD‐related infections. Causative pathogens included Pseudomonas aeruginos (1), coagulase‐negative staphylococci (2), methicillin‐resistant Staphylococcus aureus (1), a gram‐positive bacillus (1), and culture negative (2). All patients underwent complete CIED removal along with antimicrobial therapy. The three patients with CIED lead‐related endocarditis and prior LVAD infections received chronic suppressive antibiotic therapy, and one patient had LVAD exchange. All but one remained alive at the last follow‐up with a median duration of 15 months (7–46 months) from the time of CIED infection.ConclusionPatients who are receiving LVAD therapy and develop CIED infection should be managed with complete CIED removal. Chronic suppressive antibiotic therapy is warranted in cases that have concomitant LVAD infection.
Smoking and prostate cancer in a multi‐ethnic sample
Murphy, Adam B. , Akereyeni, Folasade, Nyame, Yaw A. , Guy, Mignonne C. , Martin, Iman K. , Hollowell, Courtney M.P. , Walker, Kelly, Ahaghotu, Chiledum, Kittles, Rick A.

The Prostate | July 3, 2013 | Volume: 73 | Issue: 14 | Pages: 1518-1528

10.1002/pros.22699 | PMID 23824512 Get It

ABSTRACTBACKGROUNDProstate cancer (PCa) and smoking‐related morbidity disproportionately burdens African American (AA) men. Smoking is associated with high‐grade PCa and incidence, but few studies have focused on AA men. This study aims to determine the effect of tobacco‐use on odds of PCa and of high‐grade PCa in a population of predominantly AA men.METHODSThis is a cross‐sectional study evaluating smoking and PCa status in men with incident PCa and screened healthy controls. Altogether, 1,085 men (527 cases and 558 controls), age ≥ 40 years were enrolled through outpatient urology clinics in two US cities from 2001 to 2012. Validated questionnaires were used to gather clinical and socioeconomic data.RESULTSThe cases and controls were predominantly AA (79.9% and 71.3%, respectively, P = 0.01). AA men smoked more frequently (53.4% vs. 47.9%, P < 0.001) and quit less frequently than European American (EA) men (31.5% vs. 40.4%, P = 0.01). AA heavy smokers had increased odds of PCa diagnosis (OR 2.57, 95% CI 1.09, 6.10) and high‐grade cancer (OR 1.89, 95% CI 1.03, 3.48) relative to never smokers and light smokers. Among AAs, heavy smokers had lower odds of being in the low risk stratification in the National Comprehensive Cancer Network guidelines. AA former smokers had a trend for increased odds of high‐grade cancer compared to never smokers. The associations between smokings, cancer diagnosis and cancer grade did not reach statistical significance in EA men.CONCLUSIONWe found ethnic differences in smoking behavior. Heavy smoking is associated with increased odds of PCa and of higher Gleason grade in AA men. Prostate 73: 1518–1528, 2013. © 2013 Wiley Periodicals, Inc.
Contribution of nitric oxide in the contraction-induced rapid vasodilation in young and older adults
Casey, Darren P. , Walker, Branton G., Ranadive, Sushant M. , Taylor, Jennifer L. , Joyner, Michael J. , Ranadive, Sushant

Journal of Applied Physiology | June 21, 2013 | Volume: 115 | Issue: 4 | Pages: 446-455

10.1152/japplphysiol.00446.2013 | PMID 23788575 Get It

We tested the hypothesis that reduced nitric oxide (NO) bioavailability contributes to the attenuated peak and total vasodilation following single-muscle contractions in older adults. Young ( n = 10; 24 ± 2 yr) and older ( n = 10; 67 ± 2 yr) adults performed single forearm contractions at 10, 20, and 40% of maximum during saline infusion (control) and NO synthase (NOS) inhibition via NG-monomethyl-l-arginine. Brachial artery diameters and velocities were measured using Doppler ultrasound and forearm vascular conductance (FVC; in ml·min−1·100 mmHg−1) was calculated from blood flow (ml/min) and blood pressure (mmHg). Peak and total vasodilator responses [change (Δ) in FVC from baseline] were attenuated in older adults at all intensities ( P < 0.05). NOS inhibition reduced the peak ΔFVC at 10% (88 ± 12 vs. 52 ± 9 ml·min−1·100 mmHg−1), 20% (125 ± 13 vs. 83 ± 13 ml·min−1·100 mmHg−1), and 40% (207 ± 26 vs. 133 ± 20 ml·min−1·100 mmHg−1) in young subjects, ( P < 0.05 for all) and in older adults at 10% (59 ± 5 vs. 47 ± 7 ml·min−1·100 mmHg−1, P < 0.05) and 20% (88 ± 9 vs. 68 ± 9 ml·min−1·100 mmHg−1, P < 0.05), but not 40% (128 ± 12 vs. 105 ± 11 ml·min−1·100 mmHg−1, P = 0.11). The relative (%) reduction in peak ΔFVC due to NOS inhibition was greater in young vs. older adults at 20% (−36 ± 5 vs. −23 ± 5%, P < 0.05) and 40% (−35 ± 6 vs. −16 ± 7%, P < 0.05). The reduction in the total vasodilator response (area under the curve) with NOS inhibition was also greater in young vs. older adults at all intensities. Our data suggest that contraction-induced rapid vasodilation is mediated in part by NO, and that the contribution of NO is greater in young adults.
Survival in Primary Pulmonary Hypertension with Long-Term Continuous Intravenous Prostacyclin
Barst, Robyn J., Rubin, Lewis J., McGoon, Michael D., Caldwell, Edgar J., Long, Walker A., Levy, Paul S., Rubin, Lewis J., McGoon, Michael D., Caldwell, Edgar J., Long, Walker A., Levy, Paul S.

Annals of Internal Medicine | April 12, 2013 | Volume: 121 | Issue: 6 | Pages: 409-415

10.7326/0003-4819-121-6-199409150-00003 | PMID 8053614 Get It

Prediction of headache severity (density and functional impact) after traumatic brain injury: A longitudinal multicenter study
Marwitz, Jennifer H. , Wilk, Amber R., Ketchum, Jessica M. , Hoffman, Jeanne M. , Brown, Allen W. , Lucas, Sylvia , Walker, William C.

Cephalalgia | April 10, 2013 | Volume: 33 | Issue: 12 | Pages: 998-1008

10.1177/0333102413482197 | PMID 23575819 Get It

Background: Headache (HA) following traumatic brain injury (TBI) is common, but predictors and time course are not well established, particularly after moderate to severe TBI. Methods: A prospective, longitudinal cohort study of HA severity post-TBI was conducted on 450 participants at seven participating rehabilitation centers. Generalized linear mixed-effects models (GLMMs) were used to model repeated measures (months 3, 6, and 12 post-TBI) of two outcomes: HA density (a composite of frequency, duration, and intensity) and HA disruptions to activities of daily living (ADL). Results: Although HA density and ADL disruptions were nominally highest during the first three months post-TBI, neither showed significant changes over time. At all time points, history of pre-injury migraine was by far the strongest predictor of both HA density and ADL disruptions (odds ratio (OR) = 8.0 and OR = 7.2, averaged across time points, respectively). Furthermore, pre-injury non-migraine HA (at three and six months post-TBI), penetrating-type TBI (at six months post-TBI), and female sex (at six and 12 months post-TBI) were each associated with an increase in the odds of a more severe HA density. Severity of TBI (post-traumatic amnesia (PTA) duration) was not associated with either outcome. Conclusion: Individuals with HA at three months after moderate-severe TBI do not improve over the ensuing nine months with respect to HA density or ADL disruptions. Those with pre-injury HA, particularly of migraine type, are at greatest risk for HA post-TBI. Other independent risk factors are penetrating-type TBI and, to a lesser degree and post-acutely only, female sex. Individuals with these risk factors should be monitored and considered for aggressive early intervention.
Quantitative Appraisal of Ventricular Cerebrospinal Fluid Biomarkers in Neuropathologically Diagnosed Parkinson's Disease Cases Lacking Alzheimer's Disease Pathology
Maarouf, Chera L., Beach, Thomas G., Malek‐Ahmadi, Michael , Kokjohn, Tyler A., Dugger, Brittany N. , Walker, Douglas G. , Shill, Holly A. , Jacobson, Sandra A. , Roher, Alex E., Adler, Charles H. , Sabbagh, Marwan Noel , Dugger, Brittany N

Biomarker Insights | March 12, 2013 | Volume: 8 | Issue: No issue available | Pages: BMI.S11422

10.4137/bmi.s11422 | PMID 23533154 Get It

Identifying biomarkers that distinguish Parkinson's disease (PD) from normal control (NC) individuals has the potential to increase diagnostic sensitivity for the detection of early-stage PD. A previous proteomic study identified potential biomarkers in postmortem ventricular cerebrospinal fluid (V-CSF) from neuropathologically diagnosed PD subjects lacking Alzheimer's disease (AD) neuropathology. In the present study, we assessed these biomarkers as well as p-tau 181 , Aβ42, and S100B by ELISA in PD (n = 43) and NC (n = 49) cases. The p-tau 181 /Aβ42 ratio and ApoA-1 showed statistically significant differences between groups. Multiple regression analysis demonstrated that p-tau 181 /Aβ42 had a significant odds ratio: OR = 1.42 (95% confidence interval [CI], 1.12–1.84), P = 0.006. Among the molecules investigated, intriguing correlations were observed that require further investigation. Our results suggest coexistent AD CSF biomarkers within the PD group notwithstanding that it was selected to minimize AD neuropathological lesions.
Routine Use of Gradient-Echo MRI to Screen for Cerebral Amyloid Angiopathy in Elderly Patients
Walker, D. A., Broderick, Daniel F. , Rubino, F. A., Kotsenas, Amy L.

American Journal of Roentgenology | February 28, 2013 | Volume: 182 | Issue: 6 | Pages: 1547-1550

10.2214/ajr.182.6.1821547 | PMID 15150006 Get It