The internal reference technique in microdialysis: A practical approach to monitoring dialysis efficiency and to calculating tissue concentration from dialysate samples

Scheller, D.; Kolb, J.

doi:10.1016/0165-0270(91)90114-f

Cited by 251 publications

(193 citation statements)

References 21 publications

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“…over the membrane was determined for each dialysate sample (49). The dialysate (3 l) was pipetted into a counting vial in duplicates and mixed with 3 ml scintillation fluid (Ultima Gold, Perkin Elmer, Boston, MA), and the samples were counted in a ␤-counter.…”

Section: Experimental Protocol and Methodsmentioning

confidence: 99%

Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women

Hansen

Kongsgaard²,

Holm³

et al. 2009

Journal of Applied Physiology

121

114

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Flyvbjerg A, Langberg H, Kjaer M. Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women. J Appl Physiol 106: 1385-1393, 2009. First published October 16, 2009 doi:10.1152/japplphysiol.90935.2008.-The knowledge about the effect of estradiol on tendon connective tissue is limited. Therefore, we studied the influence of estradiol on tendon synthesis, structure, and biomechanical properties in postmenopausal women. Nonusers (control, n ϭ 10) or habitual users of oral estradiol replacement therapy (ERT, n ϭ 10) were studied at rest and in response to one-legged resistance exercise. Synthesis of tendon collagen was determined by stable isotope incorporation [fractional synthesis rate (FSR)] and microdialysis technique (NH2-terminal propeptide of type I collagen synthesis). Tendon area and fibril characteristics were determined by MRI and transmission electron microscopy, whereas tendon biomechanical properties were measured during isometric maximal voluntary contraction by ultrasound recording. Tendon FSR was markedly higher in ERT users (P Ͻ 0.001), whereas no group difference was seen in tendon NH2-terminal propeptide of type I collagen synthesis (P ϭ 0.32). In ERT users, positive correlations between serum estradiol (sestradiol) and tendon synthesis were observed, whereas change in tendon synthesis from rest to exercise was negatively correlated to s-estradiol. Tendon area, fibril density, fibril volume fraction, and fibril mean area did not differ between groups. However, the percentage of medium-sized fibrils was higher in ERT users (P Ͻ 0.05), whereas the percentage of large fibrils tended to be greater in control (P ϭ 0.10). A lower Young's modulus (GPa/%) was found in ERT users (P Ͻ 0.05). In conclusion, estradiol administration was associated with higher tendon FSR and a higher relative number of smaller fibrils. Whereas this indicates stimulated collagen turnover in the resting state, collagen responses to exercise were negatively associated with s-estradiol. These results indicate a pivotal role for estradiol in maintaining homeostasis of female connective tissue. connective tissue; tendon fibrils; insulin-like growth factor-I; extracellular matrix; bone CROSS-SECTIONAL FINDINGS INDICATE that sex hormones influence tendon biomechanical properties (36), extracellular matrix adaptability in response to mechanical loading (11,21,36,41,59), and the risk of sustaining soft tissue injuries (11,24,25).Estrogen receptors have been localized in ligaments (32, 33), and tendons express transcripts for estrogen receptors (23). Nevertheless, the effect of estrogen on tendon and ligament turnover is not clarified. Thus an inhibiting effect (34, 60), no effect (51), and a stimulating effect (32) on collagen synthesis and fibroblast proliferation in vitro have been observed in anterior cruciate ligament (ACL) tissue samples. These contrasting findings are probably related to the variation between animal species and the applied methods. This ...

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Section: Experimental Protocol and Methodsmentioning

confidence: 99%

Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women

Hansen

Kongsgaard²,

Holm³

et al. 2009

Journal of Applied Physiology

121

114

View full text Add to dashboard Cite

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“…1. The microdialysis catheters were perfused at a rate of 2 l/min with Ringer acetate or NSAID solution containing radioactively labeled prostaglandin E 2 (PGE2) for relative recovery determination (14). Two different types of microdialysis catheters were used (both with a membrane length of 30 mm): custom-made, linear catheters with 3,000-kDa molecular mass cutoff (8) or commercially available CMA catheters (CMA 60; CMA/microdialysis, Solna, Sweden) with 20-kDa molecular mass cutoff.…”

Section: Methodsmentioning

confidence: 99%

Prostaglandin synthesis can be inhibited locally by infusion of NSAIDS through microdialysis catheters in human skeletal muscle

Mikkelsen¹,

Helmark²,

Kjær³

et al. 2008

Journal of Applied Physiology

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“…Five microliters of dialysate from each sample was pipetted into a counting vial, 5 ml of scintillation fluid (Ultima Gold; PerkinElmer) was added, and the sample was counted in a beta counter. The RR from the interstitial fluid to the perfusate is assumed to equal the relative loss of labeled substance from the interstitium (20). Accordingly, the RR was calculated for each location as follows:…”

Section: Patientsmentioning

confidence: 99%

Increased muscle interstitial levels of inflammatory cytokines in polymyalgia rheumatica

Kreiner¹,

Langberg²,

Galbo³

2010

Arthritis & Rheumatism

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Objective. Polymyalgia rheumatica (PMR) is characterized by aching of the proximal muscles and increased blood levels of markers of inflammation. Despite the muscle complaints, the current view is that symptoms are caused by inflammation in synovial structures. The purpose of this study was to elucidate the disease mechanisms in symptomatic muscles by measuring interstitial levels of cytokines before and after prednisolone treatment.Methods. Twenty glucocorticoid-naive patients newly diagnosed as having PMR and 20 control subjects were studied before and after 14 days of prednisolone therapy (20 mg/day). Interstitial concentrations of interleukin-1␣/␤ (IL-1␣/␤), IL-1 receptor antagonist, IL-6, IL-8, tumor necrosis factor ␣ (TNF␣), and monocyte chemoattractant protein 1 were measured in symptomatic vastus lateralis and trapezius muscles using the microdialysis technique. Plasma levels were measured simultaneously.Results. Prednisolone abolished symptoms in all of the PMR patients within 1-2 days; the erythrocyte sedimentation rate and C-reactive protein levels were normalized on day 14. In both muscles, interstitial concentrations of all cytokines were markedly higher (P < 0.05) in the PMR patients than in the controls before treatment. In both patients and controls, interstitial levels of most cytokines were higher than plasma levels, with the exception of IL-1␣ and TNF␣, which were lower in both groups. In the PMR patients, interstitial concentrations were normalized after prednisolone treatment.Conclusion. This study introduces a novel view of PMR, indicating that increased interstitial levels of inflammatory cytokines in symptomatic muscles play a role in the pathophysiology of the disease and that cytokines may be released locally. To explore the disease specificity, similar studies in other primary inflammatory conditions are warranted.

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The internal reference technique in microdialysis: A practical approach to monitoring dialysis efficiency and to calculating tissue concentration from dialysate samples

Cited by 251 publications

References 21 publications

Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women

Effect of estrogen on tendon collagen synthesis, tendon structural characteristics, and biomechanical properties in postmenopausal women

Prostaglandin synthesis can be inhibited locally by infusion of NSAIDS through microdialysis catheters in human skeletal muscle

Increased muscle interstitial levels of inflammatory cytokines in polymyalgia rheumatica

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