Matrix metalloproteinase-3 (MMP-3) is a degenerative enzyme associated with joint tissue breakdown and has been shown to be a potential biomarker of osteoarthritis. It remains unknown if synovial fluid (SF) MMP-3 concentrations following ACL injury influence gait mechanics. PURPOSE: To compare knee flexion angle (KFA) and internal knee extension moment (KEM) during gait 6 months post-ACLR in individuals with the highest concentrations of SF MMP-3 compared to those with the lowest concentrations of SF MMP-3 collected within the first 14 days of injury. METHODS: Thirty-seven individuals with ACL injury scheduled for primary patellar tendon autograft ACLR (57% females, 21±4 yrs, 23.7±2.8 BMI) participated. Individuals were grouped into highest (HQ; n=9) and lowest (LQ; n=10) quartiles based on MMP-3 knee joint SF concentrations sampled 6+4 days after ACL injury. At 6 months post-ACLR, biomechanics were collected using 3-dimensional motion capture during gait performed at a self-selected speed. Functional analyses of variance were conducted to compare KFA and KEM between HQ and LQ groups throughout stance. Groups were considered different at any percentage of stance where the 95% confidence intervals of the mean differences did not cross zero. Peak differences (PD) and corresponding effect sizes (Cohen’s d) within portions of stance demonstrating differences were also calculated. RESULTS: HQ exhibited lesser knee flexion excursion; KFA was lower during 17-24% of stance (PD: 2.1°, d=0.44) and greater during 48-100% of stance (PD: 4.5°, d=0.93). HQ also exhibited lower KEM during 14-30% and 91-100% of stance (PD: 0.72 BW, d=0.67; PD: 0.33 BW, d=1.42) and greater KEM during 45-72% of stance (PD: 0.44, d=0.76) CONCLUSION: Compared to individuals in the lowest quartile of SF MMP-3, those in the highest exhibited a stiffened knee gait strategy. Pre-surgery levels of MMP-3 following ACL injury may serve as a biomarker predicting worse gait mechanics 6 months post-ACLR.
Obesity exacerbates pain and functional limitation in persons with knee osteoarthritis (OA). In the Weight Loss and Exercise for Communities with Arthritis in North Carolina (WE-CAN) study, a community-based diet and exercise (D + E) intervention led to an additional 6 kg weight loss and 20% greater pain relief in persons with knee OA and body mass index (BMI) >27 kg/m
Plasma concentrations of leptin are highly correlated with fat mass, and are influenced by exercise and weight loss. Leptin may have an important role in predicting weight changes. It is uncertain if these effects are seen in older adults. PURPOSE To determine the changes in plasma leptin levels in older adults undergoing diet-induced weight loss and/or exercise therapy for 18-mos, and to assess baseline plasma leptin concentration as a predictor of weight loss. METHODS Older (> 60 yrs) overweight and obese (mean Body Mass Index =34.3 kg/m2) adults with knee osteoarthritis (n=316) were randomized into 1 of 4 groups: Controls (C), Exercise (Ex), Weight Loss (WL), and Ex+WL. The WL groups underwent 18 months of intervention with a weight loss goal of 5%. The Ex groups participated in a facility-based aerobic and resistance program 3 d/wk for 60 min/session for 18 mos. Plasma leptin was measured at baseline, and at 6 and 18 mos by radioimmunoassay. Change in leptin levels was analyzed by two-way repeated measures ANCOVA. A mixed model analysis examined baseline leptin as a predictor for weight loss. RESULTS Baseline leptin was a significant predictor of BMI (β=0.015;p = 0.036). Weight loss at 18 months was 5.7% of body weight for WL, 4.2% for Ex+WL, 1.8% for Ex and 1.0% for C. There was a main effect for WL (p < 0.01), but not for Ex on plasma leptin. The Ex+WL and WL groups reduced leptin levels by 6.2 ±43.7% and 10.2 ±47.3% at 18 mos, respectively. Lower levels of plasma leptin at baseline predicted weight loss (p = 0.036). CONCLUSION The WL intervention lowered plasma leptin in older adults, but the Ex intervention did not alter leptin levels. Low plasma leptin predicted greater weight loss. Supported by Claude D. Pepper Older Americans Grant 5P60AG10484-00 and General Clinical Research Center Grant M01-RR07122.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSeparation of 5S RNA from other nucleic acids by polyamino acid kieselguhr column chromatographyR. Loeser, R. Roeschenthaler, and P. HerrlichCite this: Biochemistry 1970, 9, 11, 2364–2366Publication Date (Print):May 26, 1970Publication History Published online1 May 2002Published inissue 26 May 1970https://pubs.acs.org/doi/10.1021/bi00813a021https://doi.org/10.1021/bi00813a021research-articleACS PublicationsRequest reuse permissionsArticle Views70Altmetric-Citations2LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Using three separate models that included total body mass, total lean and total fat mass, and abdominal and thigh fat as independent measures, we determined their association with knee joint loads in older overweight and obese adults with knee osteoarthritis (OA).Fat depots were quantified using computed tomography, and total lean and fat mass were determined with dual energy x-ray absorptiometry in 176 adults (age, 66.3 yr; body mass index, 33.5 kg·m) with radiographic knee OA. Knee moments and joint bone-on-bone forces were calculated using gait analysis and musculoskeletal modeling.Higher total body mass was significantly associated (P ≤ 0.0001) with greater knee compressive and shear forces, compressive and shear impulses (P < 0.0001), patellofemoral forces (P < 0.006), and knee extensor moments (P = 0.003). Regression analysis with total lean and total fat mass as independent variables revealed significant positive associations of total fat mass with knee compressive (P = 0.0001), shear (P < 0.001), and patellofemoral forces (P = 0.01) and knee extension moment (P = 0.008). Gastrocnemius and quadriceps forces were positively associated with total fat mass. Total lean mass was associated with knee compressive force (P = 0.002). A regression model that included total thigh and total abdominal fat found that both were significantly associated with knee compressive and shear forces (P ≤ 0.04). Thigh fat was associated with knee abduction (P = 0.03) and knee extension moment (P = 0.02).Thigh fat, consisting predominately of subcutaneous fat, had similar significant associations with knee joint forces as abdominal fat despite its much smaller volume and could be an important therapeutic target for people with knee OA.
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