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匹配条件： “ Robert P. Frantz and Bruce D. Johnson” ，找到相关结果约461401条。
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The Usefulness of Submaximal Exercise Gas Exchange in Pulmonary Arterial Hypertension: A Case Series
Paul R. Woods, Robert P. Frantz and Bruce D. Johnson
Clinical Medicine Insights: Circulatory, Respiratory and Pulmonary Medicine , 2012, DOI: 10.4137/CCRPM.S0

Abstract: Introduction: Submaximal exercise gas exchange may be a useful tool to track responses to therapy in pulmonary arterial hypertension (PAH) patients. Methods: Three patients diagnosed with idiopathic PAH, on differing therapies, were included. Standard clinical tests (echocardiogra- phy; 6 minute walk) were performed pre and 3–5 months after treatment. Gas exchange was measured during 3 minutes of step exercise at both time points. Results: Gas exchange variables, end tidal CO2 (PET CO2) and the ratio of ventilation to CO2 production (VE/VCO2), during submaximal exercise were able to track patient responses to therapy over a 3–5 month period. Two patients demonstrated positive improvements, with an increased PETCO2 and decreased VE/VCO2 during light exercise, in response to an altered therapeutic regime. The third patient had a worsening of gas exchange (decreased PETCO2 and increased VE/VCO2) following no changes in the medical regime from the baseline visit. Conclusion: Gas exchange variables measured during light submaximal exercise, such as PETCO2 and VE/VCO2, may be able to better detect small changes in functional status following treatment and could, therefore, be a useful tool to track disease severity in PAH patients. Further study is required to determine the clinical usefulness of these gas exchange variables.

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Gene Variant of the Bradykinin B2 Receptor Influences Pulmonary Arterial Pressures in Heart Failure Patients
Thomas P. Olson, Robert P. Frantz, Stephen T. Turner, Kent R. Bailey, Christina M. Wood and Bruce D. Johnson
Clinical Medicine Insights: Circulatory, Respiratory and Pulmonary Medicine , 2012,

Abstract: Background: Pulmonary arterial pressure (PAP) varies considerably in heart failure (HF) despite similar degrees of left ventricular (LV) dysfunction. Bradykinin alters vascular tone and common variations in the kinin B2 receptor (BDKRB2) gene exists. We hypothesized that genetic variation in this receptor would influence PAP in HF. Methods: 131 HF patients ( >1yr history systolic HF), without COPD, not currently smoking, BMI < 40, without atrial fibrillation completed the study which included a blood draw for genotyping and neurohormones (ACE, A-II, Bradykinin, ANP, BNP, and catecholamines), an echocardiogram for cardiac function and systolic PAP (PAPsys). Results: Mean LVEF was 29% ± 12%, NYHA class 2 ± 1, age 56 ± 12 yr, BMI 28 ± 5 kg/m2. Forty-six patients (35%) were homozygous for the +9 allele, 58 (44%) were heterozygous (+9/ 9) and 27 (21%) were homozygous for the 9 allele of the BDKRB2. PAPsys averaged 42 ± 13, 38 ± 12, and 35 ± 11 mmHg for +9/+9, +9/ 9 and 9/ 9, respectively (p = 0.03). There was a trend towards gene effect for plasma ACE with the highest values in +9/+9 and lowest in 9/ 9 patients (9.5 ± 10.7, 7.1 ± 8.7, and 5.4 ± 6.4 U/L, respectively, p = 0.06). There were no differences in plasma bradykinin or A-II, LVEF, or NYHA across genotypes. Conclusion: These data suggest the +9/+9 polymorphism of the BDKRB2 receptor influences pulmonary vascular tone in stable HF.

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A Polymorphism in the HLA-DPB1 Gene Is Associated with Susceptibility to Multiple Sclerosis
Judith Field,Sharon R. Browning,Laura J. Johnson,Patrick Danoy,Michael D. Varney,Brian D. Tait,Kaushal S. Gandhi,Jac C. Charlesworth,Robert N. Heard,Graeme J. Stewart,Trevor J. Kilpatrick,Simon J. Foote,Melanie Bahlo,Helmut Butzkueven,James Wiley,David R. Booth,Bruce V. Taylor,Matthew A. Brown,Justin P. Rubio,Jim Stankovich
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013454

Abstract: We conducted an association study across the human leukocyte antigen (HLA) complex to identify loci associated with multiple sclerosis (MS). Comparing 1927 SNPs in 1618 MS cases and 3413 controls of European ancestry, we identified seven SNPs that were independently associated with MS conditional on the others (each ). All associations were significant in an independent replication cohort of 2212 cases and 2251 controls () and were highly significant in the combined dataset (). The associated SNPs included proxies for HLA-DRB1*15:01 and HLA-DRB1*03:01, and SNPs in moderate linkage disequilibrium (LD) with HLA-A*02:01, HLA-DRB1*04:01 and HLA-DRB1*13:03. We also found a strong association with rs9277535 in the class II gene HLA-DPB1 (discovery set , replication set , combined ). HLA-DPB1 is located centromeric of the more commonly typed class II genes HLA-DRB1, -DQA1 and -DQB1. It is separated from these genes by a recombination hotspot, and the association is not affected by conditioning on genotypes at DRB1, DQA1 and DQB1. Hence rs9277535 represents an independent MS-susceptibility locus of genome-wide significance. It is correlated with the HLA-DPB1*03:01 allele, which has been implicated previously in MS in smaller studies. Further genotyping in large datasets is required to confirm and resolve this association.

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Active compression garment prevents tilt‐induced orthostatic tachycardia in humans
Brad Holschuh,Bruce D. Johnson,Christopher P. Johnson,Kevin L. Kelly,Lucy E. Dunne,Michael Joyner
- , 2019, DOI: 10.14814/phy2.14050

Abstract: Compression garments are used by patients with lower extremity edema to help regulate fluid distribution and to prevent orthostatic symptoms. Current compression stockings are often reported as uncomfortable and adherence is poor. The current study was conducted to assess the efficacy of a novel active compression garment on healthy individuals undergoing 60‐degree head‐up tilts for 10 min to induce venous pooling and subsequent physiological responses. During tilts while garments were on, participants’ absolute change in heart rate relative to baseline was lower (16.7 ± 8.7 BPM) compared to control (20.9 ± 11.47 BPM, P = 0.002). There were no differences in changes in mean arterial blood pressure between conditions (P = 0.303). One participant had a pre‐syncopal event which occurred during a tilt without garments. This participant did not experience pre‐syncopal symptoms with the garments on. All together, these data suggest that a novel active compression garment is capable of blunting increases in heart rate during head‐up tilt. While untested thus far in patient populations, these garments may prove efficacious in preventing orthostatic intolerance

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Revisiting Alpha-Investing: Conditionally Valid Stepwise Regression
Kory D. Johnson,Robert A. Stine,Dean P. Foster
Statistics , 2015,

Abstract: We present an algorithm, Revisiting Alpha-Investing (RAI), that provides a fast approximation to the greedy solution of the feature selection problem. RAI runs in O(np\log(n)) time and adaptively determines the number of features in the model. It approximates forward stepwise regression while avoiding over-fitting without needing to perform cross-validation. We prove that the model selected by RAI is a (1-1/$e$) approximation to the best model of the same size, under the assumption of submodularity. This assumption is quite general and allows for arbitrary collinearity in the feature matrix. We also prove a more general bound under a relaxed notion of submodularity. We compare our method to competitors on 26 data cases created from 7 real data sets to substantiate our claims.

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Submodularity in Statistics: Comparing the Success of Model Selection Methods
Kory D. Johnson,Robert A. Stine,Dean P. Foster
Statistics , 2015,

Abstract: We demonstrate the usefulness of submodularity in statistics. Greedy algorithms such as forward stepwise regression and the lasso perform well in situations that can be characterized by submodularity. In particular, submodularity of the coefficient of determination, R$^2$, provides a natural way to analyze the effects of collinearity on model selection. In model selection, we encounter the search problem of identifying a subset of k covariates with predictive loss close to that of the best model of k covariates. Submodularity arises naturally in this setting due to its deep roots within combinatorial optimization. It provides structural results for discrete convexity as well as guarantees for the success of greedy algorithms. In statistics, submodularity isolates cases in which collinearity makes the choice of model features difficult from those in which this task is routine. Submodularity of R$^2$ is closely related to other statistical assumptions used in variable screening and proving the performance of the Lasso. This has important implications for the use of model selection procedures: the situations in which forward stepwise and Lasso are successful are closely related.

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Advancing Product Quality: a Summary of the Second FDA/PQRI Conference
Adam C. Fisher,Anna Schwendeman,Arzu Selen,Ashley Boam,Barbara Allen,Bernhardt L. Trout,Brian Hasselbalch,Bruce D. Johnson,David Doleski,Diane Zezza,Emanuela Lacana,Fionnuala Walsh,G. K. Raju,Ganapathy Mohan,Geoffrey Wu,Giuseppe Randazzo,Grace McNally,Gregory Amidon,Henry Havel,Ilgaz Akseli,Janet Woodcock,Jim Polli,Joseph Famulare,Katherine Tyner,Larisa Wu,Lawrence X. Yu,Louis Yu,Mahesh Ramanadham,Margaret Caulk,Martin VanTrieste,Mary Oates,Mehul Mehta,Michael P. Thien,Moheb Nasr,Paul Seo,Paula Katz,Ramesh Sood,Richard Lostritto,Robert Iser,Robert Ju,Roger Nosal,Russell Wesdyk,Sau L. Lee,Scott Furness,Siva Vaithiyalingam,Stephen W. Hoag,Susan Rosencrance,Tara Gooen Bizjak,Thomas O’Connor,Tony Tong,Vinod Shah
- , 2016, DOI: 10.1208/s12248-016-9874-5

Abstract: The purpose of the Conference on Advancing Product Quality, under the sponsorship of the Food and Drug Administration (FDA) and Product Quality Research Institute (PQRI), is to bring regulators, industry professionals, and academic researchers together to create a synergized path toward enhanced global pharmaceutical quality. The 2015 FDA/PQRI Conference consisted of a plenary session and 20 breakout sessions arranged in four major tracks: (i) emerging regulatory initiatives; (ii) regulatory submission, assessment, and inspection; (iii) product and process development; and (iv) manufacturing, risk management, and quality assurance. This report provides a summary of the plenary session followed by each topic, as presented at the conference

Abstract: Articular cartilage health is an important issue following anterior cruciate ligament (ACL) injury and primary ACL reconstruction. Factors present at the time of primary ACL reconstruction may influence the subsequent progression of articular cartilage damage. Larger meniscus resection at primary ACL reconstruction, increased patient age, and increased body mass index (BMI) are associated with increased odds of worsened articular cartilage damage at the time of revision ACL reconstruction. Case-control study; Level of evidence, 3. Subjects who had primary and revision data in the databases of the Multicenter Orthopaedics Outcomes Network (MOON) and Multicenter ACL Revision Study (MARS) were included. Reviewed data included chondral surface status at the time of primary and revision surgery, meniscus status at the time of primary reconstruction, primary reconstruction graft type, time from primary to revision ACL surgery, as well as demographics and Marx activity score at the time of revision. Significant progression of articular cartilage damage was defined in each compartment according to progression on the modified Outerbridge scale (increase ≥1 grade) or >25% enlargement in any area of damage. Logistic regression identified predictors of significant chondral surface change in each compartment from primary to revision surgery. A total of 134 patients were included, with a median age of 19.5 years at revision surgery. Progression of articular cartilage damage was noted in 34 patients (25.4%) in the lateral compartment, 32 (23.9%) in the medial compartment, and 31 (23.1%) in the patellofemoral compartment. For the lateral compartment, patients who had >33% of the lateral meniscus excised at primary reconstruction had 16.9-times greater odds of progression of articular cartilage injury than those with an intact lateral meniscus (P < .001). For the medial compartment, patients who had <33% of the medial meniscus excised at the time of the primary reconstruction had 4.8-times greater odds of progression of articular cartilage injury than those with an intact medial meniscus (P = .02). Odds of significant chondral surface change increased by 5% in the lateral compartment and 6% in the medial compartment for each increased year of age (P ≤ .02). For the patellofemoral compartment, the use of allograft in primary reconstruction was associated with a 15-fold increased odds of progression of articular cartilage damage relative to a patellar tendon autograft (P < .001). Each 1-unit increase in BMI at the time of revision surgery was associated with a 10%

Abstract: The occurrence of physiologic knee hyperextension (HE) in the revision anterior cruciate ligament reconstruction (ACLR) population and its effect on outcomes have yet to be reported. The prevalence of knee HE in revision ACLR and its effect on 2-year outcome were studied with the hypothesis that preoperative physiologic knee HE ≥5° is a risk factor for anterior cruciate ligament (ACL) graft rupture. Cohort study; Level of evidence, 2. Patients undergoing revision ACLR were identified and prospectively enrolled between 2006 and 2011. Study inclusion criteria were patients undergoing single-bundle graft reconstructions. Patients were followed up at 2 years and asked to complete an identical set of outcome instruments (International Knee Documentation Committee, Knee injury and Osteoarthritis Outcome Score, WOMAC, and Marx Activity Rating Scale) as well as provide information regarding revision ACL graft failure. A regression model with graft failure as the dependent variable included age, sex, graft type at the time of the revision ACL surgery, and physiologic preoperative passive HE ≥5° (yes/no) to assess these as potential risk factors for clinical outcomes 2 years after revision ACLR. Analyses included 1145 patients, for whom 2-year follow-up was attained for 91%. The median age was 26 years, with age being a continuous variable. Those below the median were grouped as “younger” and those above as “older” (age: interquartile range = 20, 35 years), and 42% of patients were female. There were 50% autografts, 48% allografts, and 2% that had a combination of autograft plus allograft. Passive knee HE ≥5° was present in 374 (33%) patients in the revision cohort, with 52% being female. Graft rupture at 2-year follow-up occurred in 34 cases in the entire cohort, of which 12 were in the HE ≥5° group (3.2% failure rate) and 22 in the non-HE group (2.9% failure rate). The median age of patients who failed was 19 years, as opposed to 26 years for those with intact grafts. Three variables in the regression model were significant predictors of graft failure: younger age (odds ratio [OR] = 3.6; 95% CI, 1.6-7.9; P = .002), use of allograft (OR = 3.3; 95% CI, 1.5-7.4; P = .003), and HE ≥5° (OR = 2.12; 95% CI, 1.1-4.7; P = .03). This study revealed that preoperative physiologic passive knee HE ≥5° is present in one-third of patients who undergo revision ACLR. HE ≥5° was an independent significant predictor of graft failure after revision ACLR with a >2-fold OR of subsequent graft rupture in revision ACL surgery. NCT00625885 (ClinicalTrials.gov identifier)

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Differences in Modified Morgan Phosphorus Levels Determined by Colorimetric and Inductively Coupled Plasma Methods [PDF]
Zhongqi He, Hailin Zhang, O. Modesto Olanya, Jonathan M. Frantz, Robert P. Larkin
Open Journal of Soil Science (OJSS) , 2012, DOI: 10.4236/ojss.2012.23030

Abstract: Phosphorus (P) fertilization is frequently needed for profitable crop production. Modified Morgan P (MMP) is a soil test P used to estimate plant available P in soils. The critical values of MMP for P fertilization and maintenance recommendations are based on the P concentrations measured by a common colorimetric molybdenum blue method although other P quantification methods have also been used for MMP measurements. In this study, we collected 120 surface soil samples of Caribou Sandy loam under potato cultivation or its rotation crops from Maine, USA, and 72 soil samples of Cecil sandy loam with cotton/corn crops under conventional tillage and no-till management with chemical and poultry litter fertilization in Georgia, USA. The MMP levels in all 192 dry samples were greater when they were measured by an inductively coupled plasma (ICP)-based method, compared to the corresponding data produced from colorimetry. Our results show the two sets of data were positively and significantly correlated (r = 0.93, P < 0.001). In average, the ICP-based MMP level of the 192 samples was 23.3 mg P kg^–1 with standard deviation of 12.9, compared to the average of colorimetric MMP level of 14.9 mg P kg^–1 with standard deviation of 8.8. Based on the observations in this work, both colorimetric and ICP-based methods can be used for P fertilizer recommendation, but a conversion factor should be applied for ICP data as the current recommendation systems are based on colorimetric M&R data.

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