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Dive into the research topics where Christopher G. Jackson is active.

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Featured researches published by Christopher G. Jackson.


The New England Journal of Medicine | 1999

A trial of etanercept, a recombinant tumor necrosis factor receptor:Fc fusion protein, in patients with rheumatoid arthritis receiving methotrexate.

Michael E. Weinblatt; Joel M. Kremer; Arthur D. Bankhurst; Ken J. Bulpitt; R. Fleischmann; Robert I. Fox; Christopher G. Jackson; Mary Lange; Daniel J. Burge

BACKGROUND Patients treated with methotrexate for rheumatoid arthritis often improve but continue to have active disease. This study was undertaken to determine whether the addition of etanercept, a soluble tumor necrosis factor receptor (p75):Fc fusion protein (TNFR:Fc), to methotrexate therapy would provide additional benefit to patients who had persistent rheumatoid arthritis despite receiving methotrexate. METHODS In a 24-week, double-blind trial, we randomly assigned 89 patients with persistently active rheumatoid arthritis despite at least 6 months of methotrexate therapy at a stable dose of 15 to 25 mg per week (or as low as 10 mg per week for patients unable to tolerate higher doses) to receive either etanercept (25 mg) or placebo subcutaneously twice weekly while continuing to receive methotrexate. The primary measure of clinical response was the American College of Rheumatology criteria for a 20 percent improvement in measures of disease activity (ACR 20) at 24 weeks. RESULTS The addition of etanercept to methotrexate therapy resulted in rapid and sustained improvement. At 24 weeks, 71 percent of the patients receiving etanercept plus methotrexate and 27 percent of those receiving placebo plus methotrexate met the ACR 20 criteria (P<0.001); 39 percent of the patients receiving etanercept plus methotrexate and 3 percent of those receiving placebo plus methotrexate met the ACR 50 criteria (for a 50 percent improvement) (P<0.001). Patients receiving etanercept plus methotrexate had significantly better outcomes according to all measures of disease activity. The only adverse events associated with etanercept were mild injection-site reactions, and no patient withdrew from the study because of adverse events associated with etanercept. CONCLUSIONS In patients with persistently active rheumatoid arthritis, the combination of etanercept and methotrexate was safe and well tolerated and provided significantly greater clinical benefit than methotrexate alone.


Arthritis & Rheumatism | 2008

The effect of glucosamine and/or chondroitin sulfate on the progression of knee osteoarthritis: A report from the glucosamine/chondroitin arthritis intervention trial

Allen D. Sawitzke; Helen Shi; Martha F. Finco; Dorothy D. Dunlop; Clifton O. Bingham; Crystal L. Harris; Nora G. Singer; John D. Bradley; David Silver; Christopher G. Jackson; Nancy E. Lane; Chester V. Oddis; Fred Wolfe; Jeffrey R. Lisse; Daniel E. Furst; Domenic J. Reda; Roland W. Moskowitz; H. James Williams; Daniel O. Clegg

OBJECTIVE Osteoarthritis (OA) of the knee causes significant morbidity and current medical treatment is limited to symptom relief, while therapies able to slow structural damage remain elusive. This study was undertaken to evaluate the effect of glucosamine and chondroitin sulfate (CS), alone or in combination, as well as celecoxib and placebo on progressive loss of joint space width (JSW) in patients with knee OA. METHODS A 24-month, double-blind, placebo-controlled study, conducted at 9 sites in the United States as part of the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), enrolled 572 patients with knee OA who satisfied radiographic criteria (Kellgren/Lawrence [K/L] grade 2 or grade 3 changes and JSW of at least 2 mm at baseline). Patients with primarily lateral compartment narrowing at any time point were excluded. Patients who had been randomized to 1 of the 5 groups in the GAIT continued to receive glucosamine 500 mg 3 times daily, CS 400 mg 3 times daily, the combination of glucosamine and CS, celecoxib 200 mg daily, or placebo over 24 months. The minimum medial tibiofemoral JSW was measured at baseline, 12 months, and 24 months. The primary outcome measure was the mean change in JSW from baseline. RESULTS The mean JSW loss at 2 years in knees with OA in the placebo group, adjusted for design and clinical factors, was 0.166 mm. No statistically significant difference in mean JSW loss was observed in any treatment group compared with the placebo group. Treatment effects on K/L grade 2 knees, but not on K/L grade 3 knees, showed a trend toward improvement relative to the placebo group. The power of the study was diminished by the limited sample size, variance of JSW measurement, and a smaller than expected loss in JSW. CONCLUSION At 2 years, no treatment achieved a predefined threshold of clinically important difference in JSW loss as compared with placebo. However, knees with K/L grade 2 radiographic OA appeared to have the greatest potential for modification by these treatments.


Annals of the Rheumatic Diseases | 2010

Clinical efficacy and safety of glucosamine, chondroitin sulphate, their combination, celecoxib or placebo taken to treat osteoarthritis of the knee: 2-year results from GAIT

Allen D. Sawitzke; Helen Shi; Martha F. Finco; Dorothy D. Dunlop; Crystal L. Harris; Nora G. Singer; John D. Bradley; David Silver; Christopher G. Jackson; Nancy E. Lane; Chester V. Oddis; Fred Wolfe; Jeffrey R. Lisse; Daniel E. Furst; Clifton O. Bingham; Domenic J. Reda; Roland W. Moskowitz; H. James Williams; Daniel O. Clegg

Background Knee osteoarthritis (OA) is a major cause of pain and functional limitation in older adults, yet longer-term studies of medical treatment of OA are limited. Objective To evaluate the efficacy and safety of glucosamine and chondroitin sulphate (CS), alone or in combination, as well as celecoxib and placebo on painful knee OA over 2 years. Methods A 24-month, double-blind, placebo-controlled study, conducted at nine sites in the US ancillary to the Glucosamine/chondroitin Arthritis Intervention Trial, enrolled 662 patients with knee OA who satisfied radiographic criteria (Kellgren/Lawrence grade 2 or 3 changes and baseline joint space width of at least 2 mm). This subset continued to receive their randomised treatment: glucosamine 500 mg three times daily, CS 400 mg three times daily, the combination of glucosamine and CS, celecoxib 200 mg daily, or placebo over 24 months. The primary outcome was a 20% reduction in Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain over 24 months. Secondary outcomes included an Outcome Measures in Rheumatology/Osteoarthritis Research Society International response and change from baseline in WOMAC pain and function. Results Compared with placebo, the odds of achieving a 20% reduction in WOMAC pain were celecoxib: 1.21, glucosamine: 1.16, combination glucosamine/CS: 0.83 and CS alone: 0.69, and were not statistically significant. Conclusions Over 2 years, no treatment achieved a clinically important difference in WOMAC pain or function as compared with placebo. However, glucosamine and celecoxib showed beneficial but not significant trends. Adverse reactions were similar among treatment groups and serious adverse events were rare for all treatments.


Annals of the Rheumatic Diseases | 2008

Precision of 3.0 Tesla quantitative magnetic resonance imaging of cartilage morphology in a multicentre clinical trial

F. Eckstein; R. Buck; Deborah Burstein; Hal Cecil Charles; J. Crim; M. Hudelmaier; David J. Hunter; G. Hutchins; Christopher G. Jackson; V. Byers Kraus; Nancy E. Lane; Thomas M. Link; L. S. Majumdar; S.A. Mazzuca; Pottumarthi V. Prasad; Thomas J. Schnitzer; Mihra S. Taljanovic; A. Vaz; Bradley T. Wyman; M.-P. Hellio Le Graverand

Objective: Quantitative MRI (qMRI) of cartilage morphology is a promising tool for disease-modifying osteoarthritis drug (DMOAD) development. Recent studies at single sites have indicated that measurements at 3.0 Tesla (T) are more reproducible (precise) than those at 1.5 T. Precision errors and stability in multicentre studies with imaging equipment from various vendors have, however, not yet been evaluated. Methods: A total of 158 female participants (97 Kellgren and Lawrence grade (KLG) 0, 31 KLG 2 and 30 KLG 3) were imaged at 7 clinical centres using Siemens Magnetom Trio and GE Signa Excite magnets. Double oblique coronal acquisitions were obtained at baseline and at 3 months, using water excitation spoiled gradient echo sequences (1.0×0.31×0.31 mm3 resolution). Segmentation of femorotibial cartilage morphology was performed using proprietary software (Chondrometrics GmbH, Ainring, Germany). Results: The precision error (root mean square coefficient of variation (RMS CV)%) for cartilage thickness/volume measurements ranged from 2.1%/2.4% (medial tibia) to 2.9%/3.3% (lateral weight-bearing femoral condyle) across all participants. No significant differences in precision errors were observed between KLGs, imaging sites, or scanner manufacturers/types. Mean differences between baseline and 3 months ranged from <0.1% (non-significant) in the medial to 0.94% (p<0.01) in the lateral femorotibial compartment, and were 0.33% (p<0.02) for the total femorotibial subchondral bone area. Conclusions: qMRI performed at 3.0 T provides highly reproducible measurements of cartilage morphology in multicentre clinical trials with equipment from different vendors. The technology thus appears sufficiently robust to be recommended for large-scale multicentre trials.


Annals of the Rheumatic Diseases | 2008

Head-to-head comparison of the Lyon Schuss and fixed flexion radiographic techniques. Long-term reproducibility in normal knees and sensitivity to change in osteoarthritic knees

Marie Pierre Hellio Le Graverand; E. Vignon; Kenneth D. Brandt; S.A. Mazzuca; Muriel Piperno; R. Buck; Hal Cecil Charles; David J. Hunter; Christopher G. Jackson; V. Byers Kraus; Thomas M. Link; Thomas J. Schnitzer; A. Vaz; Bradley T. Wyman

OBJECTIVE The Lyon Schuss (LS) and fixed flexion (FF) views of the knee are superior to a conventional standing anteroposterior view in evaluating joint space narrowing (JSN) in osteoarthritis (OA). Both position the knee identically but only the LS aligns the medial tibial plateau (MTP) with the x-ray beam fluoroscopically. The present study provides the first head-to-head comparison of the LS and FF views. METHODS At baseline and 12 months, 62 OA and 99 control knees were imaged twice on the same day with LS and FF views. Minimum joint space width (mJSW) was measured by computer and MTP alignment was assessed from the distance between anterior and posterior margins of the MTP (intermargin distance, IMD). Reproducibility of measurements of mJSW and sensitivity to change were evaluated. RESULTS In normal knees, JSW did not vary over 12 months with either view. In OA knees, 12-month mJSN was 0.22 (0.43) mm with the LS view and -0.01 (0.46) mm with the FF view (p = 0.0002 and p = 0.92, respectively). Mean IMD was only half as large in LS as in FF views (0.9 (0.5) mm vs 1.9 (1.2) mm, p<0.0001). CONCLUSIONS LS and FF radiographs offer similar reproducibility in JSW measurement. However, presumably due to its superiority in aligning the MTP, the LS view is much more sensitive to JSN in OA knees.


Annals of the Rheumatic Diseases | 2010

Change in regional cartilage morphology and joint space width in osteoarthritis participants versus healthy controls: a multicentre study using 3.0 Tesla MRI and Lyon–Schuss radiography

Marie-Pierre Hellio Le Graverand; R. Buck; Bradley T. Wyman; E. Vignon; Steven A. Mazzuca; Kenneth D. Brandt; Muriel Piperno; H. Cecil Charles; M. Hudelmaier; David J. Hunter; Christopher G. Jackson; Virginia B. Kraus; Thomas M. Link; Sharmila Majumdar; Pottumarthi V. Prasad; Thomas J. Schnitzer; Austin Vaz; W. Wirth; F. Eckstein

Objective: Cartilage morphology displays sensitivity to change in osteoarthritis (OA) with quantitative MRI (qMRI). However, (sub)regional cartilage thickness change at 3.0 Tesla (T) has not been directly compared with radiographic progression of joint space narrowing in OA participants and non-arthritic controls. Methods: A total of 145 women were imaged at 7 clinical centres: 86 were non-obese and asymptomatic without radiographic OA and 55 were obese with symptomatic and radiographic OA (27 Kellgren–Lawrence grade (KLG)2 and 28 KLG3). Lyon–Schuss (LS) and fixed flexion (FF) radiographs were obtained at baseline, 12 and 24 months, and coronal spoiled gradient echo MRI sequences at 3.0 T at baseline, 6, 12 and 24 months. (Sub)regional, femorotibial cartilage thickness and minimum joint space width (mJSW) in the medial femorotibial compartment were measured and the standardised response means (SRMs) determined. Results: At 6 months, qMRI demonstrated a −3.7% “annualised” change in cartilage thickness (SRM −0.33) in the central medial femorotibial compartment (cMFTC) of KLG3 subjects, but no change in KLG2 subjects. The SRM for mJSW in 12-month LS/FF radiographs of KLG3 participants was −0.68/−0.13 and at 24 months was −0.62/−0.20. The SRM for cMFTC changes measured with qMRI was −0.32 (12 months; −2.0%) and −0.48 (24 months; −2.2%), respectively. Conclusions: qMRI and LS radiography detected significant change in KLG3 participants at high risk of progression, but not in KLG2 participants, and only small changes in controls. At 12 and 24 months, LS displayed greater, and FF less, sensitivity to change in KLG3 participants than qMRI.


Osteoarthritis and Cartilage | 2010

The human pharmacokinetics of oral ingestion of glucosamine and chondroitin sulfate taken separately or in combination.

Christopher G. Jackson; Anna Plaas; John D. Sandy; Crystal Hua; Samantha Kim-Rolands; Jamie G. Barnhill; Crystal L. Harris; Daniel O. Clegg

OBJECTIVE As part of the National Institutes of Health (NIH)-sponsored Glucosamine/Chondroitin sulfate Arthritis Intervention Trial (GAIT) our objective here was to examine (1) the pharmacokinetics (PK) of glucosamine (GlcN) and chondroitin sulfate (CS) when taken separately or in combination as a single dose in normal individuals (n=29) and (2) the PK of GlcN and CS when taken as a single dose after 3 months daily dosing with GlcN, CS or GlcN+CS, in patients with symptomatic knee pain (n=28). METHODS The concentration of GlcN in the circulation was determined by established fluorophore-assisted carbohydrate electrophoresis (FACE) methods. The hydrodynamic size and disaccharide composition of CS chains in the circulation and dosage samples was determined by Superose 6 chromatography and FACE. RESULTS We show that circulating levels of CS in human plasma are about 20 microg/ml. Most significantly, the endogenous concentration and CS disaccharide composition were not detectably altered by ingestion of CS, when the CS was taken alone or in combination with GlcN. On the other hand, the Cmax (single-dose study) and AUC values (multiple-dose study) for ingested GlcN were significantly reduced by combination dosing with CS, relative to GlcN dosing alone. CONCLUSIONS We conclude that pain relief perceived following ingestion of CS probably does not depend on simultaneous or prior intake of GlcN. Further, such effects on joint pain, if present, probably do not result from ingested CS reaching the joint space but may result from changes in cellular activities in the gut lining or in the liver, where concentrations of ingested CS, or its breakdown products, could be substantially elevated following oral ingestion. Moreover, since combined dosing of GlcN with CS was found to reduce the plasma levels seen with GlcN dosing alone, any improved pain relief by combination dosing cannot be explained by higher circulating concentrations of GlcN.


Osteoarthritis and Cartilage | 2008

Performance of a non-fluoroscopically assisted substitute for the Lyon schuss knee radiograph: quality and reproducibility of positioning and sensitivity to joint space narrowing in osteoarthritic knees

Steven A. Mazzuca; M.-P. Hellio Le Graverand; E. Vignon; David J. Hunter; Christopher G. Jackson; Virginia B. Kraus; Thomas M. Link; Thomas J. Schnitzer; A. Vaz; H.C. Charles

OBJECTIVE This study evaluated the longitudinal performance of a modified Lyon schuss (LS) knee examination in the detection of radiographic joint space narrowing (JSN) in knees with osteoarthritis (OA). The modified LS exam entails two to four iterative acquisitions with empirically adjusted angulation of the X-ray beam to achieve superimposition of the anterior and posterior margins of the medial tibial plateau (MTP), a marker of parallel radioanatomic alignment that the original LS exam achieves with fluoroscopically guided beam angulation. METHODS Seventy-four obese women with symptomatic knee OA underwent LS and fixed-flexion (FF, caudal 10 degrees beam angulation) X-ray exams at baseline and 1 year later. For 47 subjects, beam angulation for both LS exams was guided by fluoroscopy. For 27 subjects, the modified LS exam was performed at one or both times. Modified and original LS procedures were evaluated relative to concurrent FF radiographs with respect to the inter-margin distance (IMD) at the MTP midpoint (quality and reproducibility of alignment) and sensitivity to JSN. RESULTS Compared to FF radiographs, modified LS radiographs afforded a smaller mean IMD at baseline (0.89 vs 2.06 mm, P=0.002), more reproducible IMD (mean change=0.49 vs 0.91 mm, P=0.007) and more rapid JSN (mean=0.25 vs 0.02 mm/yr, P=0.005). These differences paralleled those observed between original LS and FF procedures with respect to baseline alignment (0.96 vs 1.94 mm, P<0.001), reproducibility of alignment (0.49 vs 1.00 mm, P<0.001) and sensitivity to JSN (0.16 vs -0.01 mm/yr, P=0.007). CONCLUSION In clinical centers where the absence of fluoroscopy equipment precludes use of the original LS protocol, a modified procedure employing iterative, empirical adjustment of the beam angle to achieve parallel radioanatomic alignment with the MTP affords a degree of superiority over the FF protocol with respect to quality and reproducibility of positioning and sensitivity to JSN in OA knees similar to that of the original.


Osteoarthritis and Cartilage | 2009

Subregional femorotibial cartilage morphology in women – comparison between healthy controls and participants with different grades of radiographic knee osteoarthritis

M.-P. Hellio Le Graverand; R. Buck; Bradley T. Wyman; E. Vignon; S.A. Mazzuca; Kenneth D. Brandt; Muriel Piperno; Hal Cecil Charles; M. Hudelmaier; David J. Hunter; Christopher G. Jackson; Virginia B. Kraus; Thomas M. Link; S. Majumdar; Pottumarthi V. Prasad; Thomas J. Schnitzer; A. Vaz; W. Wirth; F. Eckstein

OBJECTIVE To identify subregional differences in femorotibial cartilage morphology between healthy controls and women with different grades of radiographic knee osteoarthritis (OA). DESIGN 158 women aged > or =40 years were studied. Weight-bearing extended anterior-posterior (AP) and Lyon schuss radiographs were obtained and the Kellgren Lawrence grade (KLG) determined. 97 women had a body mass index (BMI)< or =28, no symptoms, and were AP KLG0. 61 women had a BMI> or =30, symptoms in the target knee, and mild (KLG2=31) to moderate (KLG3=30) medial femorotibial radiographic OA in the AP views. Coronal spoiled gradient echo water excitation sequences were acquired at 3.0 Tesla. Total plate and regional measures of cartilage morphology of the weight-bearing femorotibial joint were quantified. RESULTS KLG2 participants displayed, on average, thicker cartilage than healthy controls in the medial femorotibial compartment (particularly anterior subregion of the medial tibia (MT) and peripheral [external, internal] subregions of the medial femur), and in the lateral femur. KLG3 participants displayed significantly thinner cartilage than KLG0 participants in the medial weight-bearing femur (central subregion), in the external subregion of the MT, and in the internal subregion of the lateral tibia. These differences were generally unaffected when possible effects of demographic covariates were considered. CONCLUSIONS The results indicate that in femorotibial OA regional cartilage thickening and thinning may occur, dependent on the (radiographic) disease status of the joint. These changes appear to display a heterogeneous spatial pattern, where certain subregions are more strongly affected than others.


Seminars in Arthritis and Rheumatism | 1985

Chlorambucil therapy in rheumatoid arthritis: Clinical experience in 28 patients and literature review

Grant W. Cannon; Christopher G. Jackson; Cecil O. Samuelson; John R. Ward; H. James Williams; Daniel O. Clegg

Our clinical experience in 28 patients receiving chlorambucil for rheumatoid arthritis (RA) and the reports on chlorambucil therapy are reviewed. Our study population and other reports generally represent patients with severe RA who had either failed to improve or developed significant toxicity during previous treatment with conventional slow acting anti-rheumatic drugs (SAARDs). Seventy-two percent of patients had a significant clinical improvement during chlorambucil therapy and reports of complete remission are given, although the incidence of remission is unknown. Hematologic complications are often reported, but appeared more frequently in our experience than previously reported. Hematologic toxicity required that chlorambucil be discontinued in the majority of our cases. Two deaths from suspected drug induced malignancies are reported. Although chlorambucil appears to be effective in the control of active RA, the potential for drug induced toxicity and malignancies may outweigh the benefit of continued use of this experimental therapy in RA.

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Thomas M. Link

University of California

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David J. Hunter

Royal North Shore Hospital

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A. Vaz

University of Arizona

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