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Dynamic 31P MR spectroscopy of plantar flexion: influence of ergometer design, magnetic field strength (3 and 7 T), and RF-coil design.
Šedivý, P, Kipfelsberger, MC, Dezortová, M, Krššák, M, Drobný, M, Chmelík, M, Rydlo, J, Trattnig, S, Hájek, M, Valkovič, L
Medical physics. 2015;(4):1678-89
Abstract
PURPOSE Dynamic phosphorus magnetic resonance spectroscopy ((31)P MRS) during and after acute exercise enables the noninvasive in vivo determination of the mitochondrial capacity of skeletal muscle. Nevertheless, the lack of standardization in experimental setups leads to significant variations in published values of maximal aerobic capacity, even in the population of healthy volunteers. Thus, in this study, we aimed to assess the impact of the ergometer type (pneumatic and mechanical resistance construction), radiofrequency (RF)-coil diameter, and different magnetic field strengths (3 and 7 T) on the metabolic parameters measured by dynamic (31)P MRS during a plantar flexion isotonic exercise protocol within the same group of healthy volunteers. METHODS Dynamic (31)P MRS measurements of the calf muscle in 11 volunteers (mean age, 36 ± 13 yrs; mean BMI, 23.5 ± 2.5 kg/m(2)), on a 3 T MR system with a custom-made mechanical ergometer in the first research laboratory (RL1) and on 3 and 7 T MR systems equipped with a commercial pneumatic ergometer in the second research laboratory (RL2), were performed at three different workloads. RF-coils differed slightly between the sites and MR systems used. The repeatability of the experimental protocol was tested in every setup. The basal concentrations of phosphocreatine (PCr), exercise-induced depletion of PCr (ΔPCr), initial PCr resynthesis rate (VPCr), and mitochondrial capacity (Qmax) were calculated and compared between the research sites and field strengths. RESULTS High repeatability of the measurement protocol was found in every experimental setup. No significant differences at any workload were found in these metabolic parameters assessed at different magnetic field strengths (3 T vs 7 T), using the same ergometer (in RL2) and a similar RF-coil. In the inter-research laboratory comparison at the same field strength (3 T), but with using different ergometers and RF-coils, differences were found in the concentration of PCr measured at rest and in the drop in PCr signal intensity. These differences translated into difference in the value of mitochondrial capacity at a workload of 15% of maximal voluntary contraction (MVC) force (0.45 ± 0.16 mM/s vs 0.31 ± 0.08 mM/s, in the RL1 and RL2, respectively). CONCLUSIONS Metabolic parameters measured during exercise challenge by dynamic (31)P MRS do not depend upon the magnetic field strength used. For multicenter studies with different ergometers, it is important to set the same workload, measurement, and evaluation protocols, especially when the effects of very mild exercise (15% MVC) are to be compared. However, a higher workload (24% MVC) decreases the influence of imperfections and intersite differences for the assessed value of maximal mitochondrial capacity.
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Prevention of serious vascular events by aspirin amongst patients with peripheral arterial disease: randomized, double-blind trial.
, , Catalano, M, Born, G, Peto, R
Journal of internal medicine. 2007;(3):276-84
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Abstract
OBJECTIVE To assess the prophylactic efficacy of aspirin and a high-dose antioxidant vitamin combination in patients with peripheral arterial disease (PAD) in terms of reduction of the risk of a first vascular event (myocardial infarction, stroke, vascular death) and critical limb ischaemia. DESIGN Randomized, placebo-controlled, double-blind clinical trial with 2 x 2 factorial design. SETTING Thirty-seven European angiology/vascular medicine units. SUBJECTS A total of 366 outpatients with stage I-II PAD documented by angiography or ultrasound, with ankle/brachial index <0.85 or toe index <0.6; 210 patients completed the follow-up. INTERVENTIONS Four treatment groups: (i) oral aspirin (100 mg daily), (ii) oral antioxidant vitamins (600 mg vitamin E, 250 mg vitamin C and 20 mg beta-carotene daily), (iii) both or (iv) neither, given for 2 years. MAIN OUTCOME MEASURE Major vascular events (cardiovascular death, myocardial infarction or stroke) and critical leg ischaemia. RESULTS Seven of 185 patients allocated aspirin and 20 of 181 allocated placebo suffered a major vascular event (risk reduction 64%, P = 0.022); five and eight patients, respectively, suffered critical leg ischaemia (total 12 vs. 28, P = 0.014). There was no evidence that antioxidant vitamins were beneficial (16/185 vs. 11/181 vascular events). Neither treatment was associated with any significant increase in adverse events. Inclusion of this trial in a meta-analysis of other randomized trials of anti-platelet therapy in PAD makes the overall results highly significant (P < 0.001) and suggests that low-dose aspirin reduces the incidence of vascular events by 26%. CONCLUSIONS For the first time direct evidence shows that low-dose aspirin should routinely be considered for PAD patients, including those with concomitant type 2 diabetes.
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A randomised trial of rigid stump dressing following trans-tibial amputation for peripheral arterial insufficiency.
Woodburn, KR, Sockalingham, S, Gilmore, H, Condie, ME, Ruckley, CV, , , ,
Prosthetics and orthotics international. 2004;(1):22-7
Abstract
BACKGROUND A multicentre randomised controlled trial to determine the effect of a rigid plaster dressing applied at the time of trans-tibial amputation on the number of days to casting for a prosthesis, and the incidence of post-operative stump infection. METHODS Patients requiring trans-tibial amputation were randomised to one of 2 groups: In Group 1 (intervention) a rigid above-knee plaster dressing was applied at operation and patients were managed according to a standard protocol. Group 2 (control) had the individual surgeons' usual non-rigid dressing regime. Rehabilitation data were extracted from the national physiotherapy database. On completion of the trial a questionnaire was sent to all participants. RESULTS 14 surgeons in 7 centres enrolled 154 patients, with 96 ultimately cast for a prosthesis. Patients who received a rigid dressing (n = 78) had reduced days to casting (median 36, confidence interval 30-47) when compared with other dressings (n = 76) (median 42, confidence interval 36-45), these differences did not reach statistical significance. There was no significant difference in post-operative infection rates in the two groups. 64% of surgeons, and all physiotherapists and vascular nurses responding to the post-trial questionnaire felt that the rigid dressing was an improvement on their normal regime and wished to continue with the technique. CONCLUSIONS Despite a median reduction of 6 days in time to casting in patients treated with a rigid post-operative dressing this failed to reach statistical significance. The majority of participants who replied to the post-trial questionnaire expressed a wish to continue using the rigid dressing technique. To confirm that the trends shown in this trial are statistically valid a larger trial is needed.
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Quantification of leg oedema in postmenopausal hypertensive patients treated with lercanidipine or amlodipine.
Lund-Johansen, P, Stranden, E, Helberg, S, Wessel-Aas, T, Risberg, K, Rønnevik, PK, Istad, H, Madsbu, S
Journal of hypertension. 2003;(5):1003-10
Abstract
OBJECTIVE Of the study was to compare the leg oedema-forming potential of two different dihydropyridine calcium channel blockers in postmenopausal women. DESIGN A total of 92 postmenopausal hypertensive patients [systolic blood pressure (SBP) 150-179 mmHg or diastolic blood pressure (DBP) 95-109 mmHg were randomized to receive a 4-week treatment with either 10 mg/day lercanidipine (n = 48) or 5 mg/day amlodipine (n = 44), with force-titration to 20 and 10 mg/day, respectively for an additional 4 weeks. METHODS Leg volume was measured by water displacement volumetry, patients were questioned for symptoms and a physical examination was performed to detect the presence of oedema. RESULTS A total of 77 patients completed the study, without a major protocol violation and were included in the primary analysis. Leg volume increase from baseline was significantly higher in the amlodipine than in the lercanidipine group (60.4 +/- 8.6 versus 5.3 +/- 8.1 ml; P < 0.001). The percentage of patients with evidence of oedema on physical examination (33.3 versus 9.8%, P = 0.011) and with symptoms of leg swelling (63.9 versus 22%, P < 0.001) and leg heaviness (47.2 versus 12.2%, P < 0.001) was also greater with amlodipine compared with lercanidipine. A positive correlation was found between leg volume and sign or symptoms of oedema (P < 0.001). Both drugs reduced SBP and DBP, with no significant differences between treatments. No correlation was found between leg volume changes from baseline and the antihypertensive effect of either drug. CONCLUSIONS In postmenopausal females with mild to moderate hypertension the oedema formation of Lercanidipine was significantly less than that of Amlodipine, despite no significant differences in the antihypertensive effect.
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MR venography using an intravascular contrast agent: results from a multicenter phase 2 study of dosage.
Larsson, EM, Sundén, P, Olsson, CG, Debatin, J, Duerinckx, AJ, Baum, R, Hahn, D, Ebner, F
AJR. American journal of roentgenology. 2003;(1):227-32
Abstract
OBJECTIVE The objective of this study was to determine the optimal dose of the iron oxide contrast agent feruglose for contrast-enhanced MR venography of the abdominopelvic and lower extremity veins and to evaluate its safety and tolerability in patients with deep venous thrombosis. SUBJECTS AND METHODS We enrolled in our study a total of 45 patients at six centers who had lower extremity deep venous thrombosis documented on radiographic venography. Forty-four patients received the study drug; 39 completed the study. Each patient received three sequential IV injections of feruglose at doses of 0.75, 1.25, and 3.0 mg Fe/kg body weight. MR venography at 1.5 T was repeated at three levels after each dose. Safety was evaluated. RESULTS The agreement between contrast-enhanced MR venography and radiographic venography with regard to deep venous thrombosis above the knee was zero at the lowest dose (0.75 mg Fe/kg body weight), 43% at the dose 2.0 mg Fe/kg body weight, and 49% at the dose 5.0 mg Fe/kg body weight. No significant difference was seen between the two highest doses. The highest cumulative dose provided the greatest diagnostic usefulness score. No serious adverse events occurred. CONCLUSION The two highest doses of feruglose showed the best agreement between contrast-enhanced MR venography and radiographic venography for deep venous thrombosis above the knee. The safety and tolerability of feruglose were confirmed.
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The risk of ipsilateral versus contralateral recurrent deep vein thrombosis in the leg. The DURAC Trial Study Group.
Lindmarker, P, Schulman, S
Journal of internal medicine. 2000;(5):601-6
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Abstract
OBJECTIVES To investigate the risk of ipsilateral versus contralateral recurrent deep vein thrombosis in the leg. DESIGN An open prospective long term follow-up multicentre trial. Patients were followed by frequent outpatient visits at each centre during the first 12 months after inclusion and thereafter annually. SETTING Sixteen hospitals in central Sweden. SUBJECTS A total of 790 consecutive patients with objectively verified first episode of acute deep vein thrombosis and without diagnosed malignant disease were recruited from a randomized study comparing 6 weeks with 6 months of oral antivitamin K therapy as secondary thromboprophylaxis. MAIN OUTCOME MEASURES Deep vein thrombosis in the contralateral leg was confirmed by venography or ultrasound. With regard to the ipsilateral leg, venography was required. RESULTS A recurrent episode of venous thromboembolism was documented in 192 patients after a mean (+/-SD) period of 31(+/-29) months. In 26 additional patients with ipsilateral symptoms the diagnostic critera were not fulfilled. One hundred and eleven patients have deceased and 69 patients withdrew from the study. The 392 patients without recurrent episodes were followed for a median of 96 months with 90% for at least 48 months. An objectively verified recurrent contralateral and ipsilateral deep vein thrombosis occurred in 95 and 54 cases, respectively, and in 41 patients pulmonary embolism was documented. In two patients thromboses with unusual locations were registered. The risk of contralateral versus ipsilateral recurrence was significantly increased with a risk ratio of 1.6 (95% confidence interval 1.4-1.9) in a time to event model. In a multivariate analysis none of the investigated variables were significantly associated with the side of recurrent thrombosis. CONCLUSIONS The risk of a recurrent deep vein thrombosis is increased in the contralateral leg. This brings into question the importance of an impaired venous flow for recurrent episodes of thrombosis.