bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in Achilles tendon moment arm from rest to maximum isometric plantarflexion: in vivo observations in man
Authors: Maganaris Constantinos N. , Baltzopoulos Vasilios , Sargeant Anthony J. 
Published: September 2004

The purpose of the present study was to examine the effect of a plantarflexor maximum voluntary contraction (MVC) on Achilles tendon moment arm length.
Sagittal magnetic resonance (MR) images of the right ankle were taken in six subjects both at rest and during a plantarflexor MVC in the supine position at a knee angle of 90 deg and at ankle angles of ‐30 deg (dorsiflexed direction), ‐15 deg, 0 deg (neutral ankle position), +15 deg (plantarflexed direction), +30 deg and +45 deg. A system of mechanical stops, support triangles and velcro straps was used to secure the subject in the above positions. Location of a moving centre of rotation was calculated for ankle rotations from ‐30 to 0 deg, ‐15 to +15 deg, 0 to +30 deg and +15 to +45 deg. All instant centres of rotation were calculated both at rest and during MVC. Achilles tendon moment arms were measured at ankle angles of ‐15, 0, +15 and +30 deg.
At any given ankle angle, Achilles tendon moment arm length during MVC increased by 1‐1.5 cm (22‐27 %, P < 0.01) compared with rest. This was attributed to a displacement of both Achilles tendon by 0.6‐1.1 cm (P < 0.01) and all instant centres of rotation by about 0.3 cm (P < 0.05) away from their corresponding resting positions.
The findings of this study have important implications for estimating loads in the musculoskeletal system. Substantially unrealistic Achilles tendon forces and moments generated around the ankle joint during a plantarflexor MVC would be calculated using resting Achilles tendon moment arm measurements.
Determination of both the time constant of v̇O2 and Δv̇O2/ΔW from a single incremental exercise test: validation and repeatability
Authors: Wisén Anita G. M. , Wohlfart Björn 
Published: September 2004

SummaryA single incremental cycle exercise test including a steady‐state load, combined with respiratory gas exchange, was performed with the objective of determining the time constant (o2) and the amount of oxygen required at each load (o2/ΔW) by using a novel equation. The protocol was validated using four exercise tests at different constant loads and conventionally fitted mono‐exponential functions to determine o2, and interpolation of o2 versus load to determine o2/ΔW. No significant differences were seen between the means of either o2 or o2/ΔW determined with the two protocols. The correlation coefficient was 0·62 for o2 and 0·48 for o2/ΔW. The absolute differences (2 SD) were 11·6 s for o2 and 1·1 ml min−1 W−1 for o2/ΔW. The equations were compared in the same steady‐state test and good agreement of o2 was obtained (R = 0·99). The 5–6‐week repeatability (incremental test) was evaluated. No statistical differences were seen between the mean of the repeated tests. The difference between the tests (2 SD) were 20 s for o2 and 1·2 ml min−1 W−1 for o2/ΔW. In conclusion, o2 and o2/ΔW can be determined from a single incremental test. The validation showed an acceptable agreement, although the variations in absolute values were not negligible. This could partly be explained by the natural day‐to‐day variation and fluctuations in incoming raw data. The test–retest variation in absolute values was considerable, which must be taken into account when using o2 and o2/ΔW for evaluation of aerobic function.
Microvascular response in guinea pig skin to histamine challenge with and without application of skin window
Authors: Evilevitch Vladimir , Norrgren Kristina , Greiff Lennart , Wollmer Per 
Published: September 2004

SummaryWe measured the microvascular response to histamine in guinea pig skin. Histamine (40 mg ml−1) was given either as a skin prick test or applied topically onto a skin window. The skin window was prepared by applying suction and gentle warming to the skin so that a blister was formed, and by removing the top of the blister. The microvascular response was measured as the accumulation of radiolabelled transferrin in the skin in vivo, reflecting a combination plasma exudation and vasodilatation. In the control (saline) challenge, the response was slightly greater in the skin window than after skin prick challenge and the scatter was larger. Histamine challenge resulted in a significant microvascular response with respect to the control situation when measured immediately after provocation for both challenge techniques. Ten minutes after challenge, a smaller response was measured, which was still significantly greater than control for the skin prick challenge, but not for topical provocation using the skin window technique. We conclude that the microvascular response to histamine after provocation with the skin prick technique is similar to that after topical provocation using the skin window technique. The skin window technique may have a lower sensitivity than the skin prick technique owing to a higher scatter in the control situation. This difference should be considered when performing and interpreting studies of the microvascular reaction in the skin.
Chronotropic incompetence to exercise separates low body weight from established anorexia nervosa
Authors: Roche Frédéric , Barthélémy Jean‐Claude , Garet Martin , Costes Frédéric , Pichot Vincent , Duverney David , Kadem Myriam , Millot Luc , Estour Bruno 
Published: September 2004

SummaryChronotropic incompetence (CI), characterized by an attenuated heart rate (HR) response to exercise could participate to the limitation of exercise capacity in anorexia nervosa (AN). Therefore, we evaluated the role of cardiac sympathetic responsiveness in AN patients. In addition, the ambulatory value of autonomic control using spectral analysis of heart rate variability (HRV) was determined and correlated to maximal exercise performance. Twenty‐two patients hospitalized for weight loss and suspicion of AN were included in the study. All performed a symptom‐limited exercise test with measurement of gas exchange for chronotropic response to exercise evaluation. Holter ECG recordings allowed daytime and night‐time spectral domain HRV analysis in order to evaluate the alteration of sympathetic control of HR in free‐living conditions. CI defined as a failure to achieve 80% of heart rate reserve (%HRR) was observed in 13 (59%) patients (CI+). This group presented a higher body mass deficit than the group without CI (CI−; −35·1 ± 8·7% versus −26·1 ± 10·7%; P<0·05). Obviously, patients with a lower body mass index (BMI < 16 kg m−2, n = 14) revealed a more severe limitation to maximal exercise with a lower peak HR, a lower peak Vo2, and a lower maximal O2 pulse (P<0·05). BMI was significantly correlated to peak Vo2, maximal HR, and %HRR achieved at peak exercise. Daytime HRV parameters reflecting the sympathetic autonomic equilibrium (LF nu, LF/HF ratio) were significantly lower in CI+ patients. Blunted sympathetic response to maximal exercise is frequent and correlated to weight deficit. The present data suggest a major autonomic derangement in AN characterized by a cardiac sympathetic withdrawal.
Myocardial velocities measured during adenosine, dobutamine and supine bicycle exercise: a tissue Doppler study in healthy volunteers
Authors: Saha Samir K. , Brodin Lars‐Åke , Lind Britta , Svedenhag Jan , Strååt Eva , Gunnes Sigurd 
Published: September 2004

SummaryBackground:  Dobutamine stress echocardiography (DSE) quantified by tissue Doppler (TVI) have improved the diagnostic capacity of the procedure. Quantification of other stress modalities, e.g. adenosine stress echo (ASE) and exercise stress echocardiography (ESE) are necessary for assessing any pathophysiological differences in different forms of stress.Methods:  Ten healthy individuals underwent ASE, DSE, and ESE during a span of 2–5 days. Left ventricular (LV) apical images at rest and peak stress (max) were postprocessed using TVI on a GE System FiVe equipment. ECG‐derived QRS duration (QRSD, ms), heart rate (HR, bpm), TVI‐estimated basal systolic velocities (S2V, cm s−1), ejection time (S2T, ms) and strain (S, %) were computed off‐line and compared. Longitudinal displacement imaging, tissue tracking, was also made.Results:  Data for ASE, DSE and ESE during peak stress were (HR: 84 ± 12***, 142 ± 19, 137 ± 27; P<0·001) (QRSD: 92 ± 18**, 74 ± 13, 79 ± 9; P<0·05), (S2T: 307 ± 34***, 175 ± 53, 192 ± 25; P<0·001) and (S%: 26·0 ± 3·0, 21·2 ± 7·3, 22·1 ± 5·1; P = n.s.) respectively. Velocity response, registered in the LV septum at max, was lowest during ASE (7·4 ± 1·4) highest during DSE (13·0 ± 2·7; P<0·001 versus ASE) and somewhat intermediate during ESE (11·3 ± 3·5; P<0·001 versus ASE). In contrast, strain and displacement did not differ.Conclusion:  ASE evokes significantly less LV systolic response compared with both DSE and ESE. Increased velocity (P<0·05 versus rest) and strain (P>0·05) response at a much lower HR indicates that adenosine has minor effects on contraction presumably secondary to vasodilatation. Powerful chronotropic response to DSE and ESE is probably prerequisite for strong velocity response at the expense of strain and displacement. TVI‐assisted stress echocardiography thereby shows different LV systolic response in healthy individuals, depending on stress modality.
Determination of the left ventricular long‐axis orientation from a single short‐axis MR image: relation to BMI and age
Authors: Engblom Henrik , Hedström Erik , Palmer John , Wagner Galen S. , Arheden Håkan 
Published: September 2004

SummaryAccurate determination of imaging planes in relation to the left ventricular (LV) long‐axis orientation is important for anatomical and functional evaluation as well as for serial comparisons with cardiac magnetic resonance (CMR) imaging. Therefore, a fast and reliable method to test the accuracy of CMR imaging for measuring the orientation of the LV long‐axis was developed and validated. In addition, the relationship between LV long‐axis orientation and body mass index (BMI), gender and age was assessed. Two approaches were used, a long‐axis approach (based on a manually defined vector) and a short‐axis approach (based on a calculated vector). The concordance between the two approaches was assessed in 72 healthy volunteers. The accuracy and precision of MR imaging for measuring three‐dimensional orientations were tested using a LV phantom. The mean difference between the long‐ and short‐axis approaches for measuring the LV long‐axis orientation in the study population was 0 ± 3°, 0 ± 2°, and −1 ± 3° in the frontal, transverse and sagittal plane, respectively. BMI and age were shown to influence LV long‐axis orientation, especially in the frontal and sagittal planes. A significant difference in LV long‐axis orientation in the frontal and sagittal planes was found between genders. The correlation coefficient between MR‐measured phantom orientation and true phantom orientation was >0·98 in all three orthogonal planes. These observations suggest that a single LV short‐axis MR image can be used for measuring LV long‐axis orientation in patients with no cardiac disease.
Prevalence and Diagnosis of Migraine in Patients Consulting Their Physician With a Complaint of Headache: Data From the Landmark Study
Authors: Tepper Stewart J. , Dahlöf Carl G.H. , Dowson Andrew , Newman Lawrence , Mansbach Hank , Jones Martin , Pham Ba , Webster Chris , Salonen Reijo 
Published: September 2004

Context.—Headache experts have suggested that to improve the recognition of migraine, patients with a stable pattern of episodic, disabling headache and a normal physical exam should be considered to have migraine in the absence of contradictory evidence. The premise upon which this approach is based—that is, that episodic, recurrent primary headache in the clinic is usually migraine—has not been evaluated in prospective clinical studies.Objectives.—To (1) evaluate the diagnoses of patients consulting their physician with primary episodic headache and (2) compare clinic diagnoses and patient self‐diagnoses with International Headache Society (IHS) headache diagnoses assigned on the basis of longitudinal data from patient diaries.Design.—Prospective, open‐label study. During the screening visit, patients self‐reported a headache diagnosis and then were assigned a headache diagnosis by their physician following his or her customary practice. Patients with a new physician diagnosis of migraine or nonmigraine primary headache were given diaries to record headache symptoms for up to 3 months or 6 attacks. Members of an expert panel, unaware of the clinic diagnosis, used diary data to assign a headache diagnosis to each attack and to each patient.Setting.—One hundred twenty‐eight (128) practices in 15 countries including the United States.Patients.—A total of 1203 male and female patients between 18 and 65 years of age who consulted their physician with headache as a primary or secondary complaint.Results.—Overall, 94% of patients with a physician diagnosis of nonmigraine primary headache or a new clinic diagnosis of migraine had IHS‐defined migraine (76%) or probable migraine (migrainous) (18%) headache on the basis of longitudinal diary data. A new clinic diagnosis of migraine was almost always correct: 98% of patients with a clinic diagnosis of migraine had IHS‐defined migraine (87% of patients) or probable migraine (11% of patients) headache on the basis of longitudinal diary data. On the other hand, review of diaries of patients with a clinic diagnosis of nonmigraine revealed that 82% of these patients had IHS‐defined migraine (48%) or probable migraine (34%) headache. Altogether, one in four patients (25%) with IHS‐defined migraine according to longitudinal diary data did not receive a clinic diagnosis of migraine.Conclusions.—These findings support the diagnostic approach of considering episodic, disabling primary headaches with an otherwise normal physical exam to be migraine in the absence of contradictory evidence. If in doubt of diagnosis or when assigning a nonmigraine diagnosis, strong consideration should be given to the use of a diary to confirm primary headache diagnosis.
A Combination of Riboflavin, Magnesium, and Feverfew for Migraine Prophylaxis: A Randomized Trial
Authors: Maizels Morris , Blumenfeld Andrew , Burchette Raoul 
Published: September 2004

Objective.—To determine the efficacy for migraine prophylaxis of a compound containing a combination of riboflavin, magnesium, and feverfew.Background.—Previous studies of magnesium and feverfew for migraine prophylaxis have found conflicting results, and there has been only a single placebo‐controlled trial of riboflavin.Design/Methods.—Randomized double‐blind placebo‐controlled trial of a compound providing a daily dose of riboflavin 400 mg, magnesium 300 mg, and feverfew 100 mg. The placebo contained 25 mg riboflavin. The study included a 1‐month run‐in phase and 3‐month trial. The protocol allowed for 120 patients to be randomized, with a preplanned interim analysis of the data after 48 patients had completed the trial.Results.—Forty‐nine patients completed the 3‐month trial. For the primary outcome measure, a 50% or greater reduction in migraines, there was no difference between active and “placebo” groups, achieved by 10 (42%) and 11 (44%), respectively (P= .87). Similarly, there was no significant difference in secondary outcome measures, for active versus placebo groups, respectively: 50% or greater reduction in migraine days (33% and 40%, P= .63); or change in mean number of migraines, migraine days, migraine index, or triptan doses. Compared to baseline, however, both groups showed a significant reduction in number of migraines, migraine days, and migraine index. This effect exceeds that reported for placebo agents in previous migraine trials.Conclusion.—Riboflavin 25 mg showed an effect comparable to a combination of riboflavin 400 mg, magnesium 300 mg, and feverfew 100 mg. The placebo response exceeds that reported for any other placebo in trials of migraine prophylaxis, and suggests that riboflavin 25 mg may be an active comparator. There is at present conflicting scientific evidence with regard to the efficacy of these compounds for migraine prophylaxis.
Rizatriptan 5 mg for the Acute Treatment of Migraine in Adolescents: Results From a Double‐Blind, Single‐Attack Study and Two Open‐Label, Multiple‐Attack Studies
Authors: Hester Visser W. , Winner Paul , Strohmaier Kim , Klipfel Meghan , Peng Yahong , McCarroll Kathleen , Cady Roger , Lewis Donald , Nett Robert ,   on behalf of the Rizatriptan Protocol 059 and 061 Study Groups
Published: September 2004

Objective.—To examine the short‐ and long‐term efficacy and tolerability of rizatriptan 5 mg in adolescents with migraine.Methods.—Two studies were conducted in patients aged 12 to 17 years. The first study was a randomized, double‐blind, placebo‐controlled, single‐attack study followed by a randomized, 1‐year, open‐label extension. The second study was a randomized, 1‐year, open‐label study. In the single‐attack study, patients treated a moderate or severe migraine headache and up to two recurrences with rizatriptan 5‐mg tablets (n = 234) or placebo (n = 242). Patients were instructed to use the study medication only on nonschool days. Headache severity, associated symptoms, and functional disability were assessed by the patient at 0.5, 1, 1.5, 2, 3, and 4 hours after the initial dose. In the 1‐year studies, patients treated up to 6 migraine attacks per month with rizatriptan 5‐mg tablets (n = 273), rizatriptan 5‐mg wafers (n = 281), or standard care therapy (n = 132). Headache severity was assessed by the patient at 2 hours after the initial dose. In all studies, the primary efficacy measure was pain relief at 2 hours post dose.Results.—In the single‐attack study, the proportion of patients with pain relief at 2 hours was not significantly different between rizatriptan 5 mg (68.2%) and placebo (68.8%). Fewer patients than expected (about 30%) treated their migraine attacks on the weekend. Among these patients, the proportion with pain relief at 2 hours was significantly higher in the rizatriptan group than in the placebo group (74% vs. 58%, P = 0.022). In the multiple‐attack studies, pain relief at 2 hours was achieved in significantly more attacks treated with rizatriptan 5‐mg tablet (77%) or with rizatriptan 5‐mg wafer (77%) than with standard care (64%). Rizatriptan 5 mg was well tolerated in both the studies, with an adverse event profile not significantly different from that of placebo or standard care.Conclusions.—Rizatriptan 5 mg was not more effective than placebo in the treatment of a single migraine attack in adolescents, but appeared to be more effective than standard care for treating multiple attacks occurring over 1 year in these patients. Rizatriptan 5 mg was well tolerated in adolescents during short‐term and long‐term use.
Migraine Treatment With Rizatriptan and Non‐Triptan Usual Care Medications: A Pharmacy‐Based Study
Authors: Cady Roger , Martin Vincent , Adelman James , Diamond Merle , Sajjan Shiva , Henry Hu X. 
Published: September 2004

Objective.—To compare the effectiveness of rizatriptan to other non‐triptan medications in the relief of migraine headache in usual care settings.Background.—Although rizatriptan has been shown to provide effective relief of migraine symptoms in clinical trials, limited data exist directly comparing its effectiveness with non‐triptan medications.Methods.—Migraineurs aged 18 to 55 who had been prescribed a new antimigraine drug (rizatriptan 10 mg or a selected class of non‐triptan oral medications) were recruited to participate in the study through a national retail pharmacy chain. Participants completed a baseline questionnaire at the enrollment and reported their treatment experiences by filling out the treatment diary after using the newly prescribed medication. The treatment outcomes of patients receiving rizatriptan were compared with those receiving non‐triptan medications. Logistic regression analysis was applied to test statistical significance with adjustment for potential confounding factors.Results.—Of the 728 patients who entered the study, 693 (95.2%) completed the treatment diary. Patients treated with rizatriptan (192) and non‐triptans (501) reported the following outcomes, respectively—onset of headache relief within 30 minutes post‐dose: 25% versus 18%; self‐defined significant headache relief within 2 hours post‐dose: 71% versus 54%; pain free or mild pain at 2 hours post‐dose: 58% versus 47%; completely symptom‐free within 2 hours of post‐dose: 32% versus 20%; return to usual activities within 2 hours post‐dose: 39% versus 35%; and satisfied with treatment: 67% versus 55% (P < .05 in all comparisons with exception of returning to usual activities).Conclusion.—Rizatriptan was significantly more effective than non‐triptans in the relief of migraine headaches for patients obtaining prescribed migraine medications from a retail pharmacy. Additional studies at other usual care settings may be needed to confirm the findings.
Role of platelet surface glycoprotein Ibα and P‐selectin in the clearance of transfused platelet concentrates
Authors: Leytin Valery , Allen David J. , Gwozdz Adam , Garvey Bernadette , Freedman John 
Published: September 2004

BACKGROUND:  Role of P‐selectin (CD62) and glycoprotein (GP) Ibα in posttransfusion clearance of platelet concentrates (PCs) is unclear.STUDY DESIGN AND METHODS:  Platelet (PLT) activation in vitro was determined by flow cytometry using anti‐CD62 and anti‐GPIbα. PC clearance in vivo was evaluated in an animal model using rabbits with an inhibited reticuloendothelial system, as measured by 0.5‐hour (R0.5), 24‐hour (R24), and total (R∑) PLT recoveries, and survival time (ST). Correlations were analyzed between in vitro assays of PLT activation and in vivo clearance of conventional (Days 2‐5), outdated (Days 7‐8), and refrigerated PCs.RESULTS:  Binding of anti‐CD62 to the PLT surface was significantly increased and of anti‐GPIbα decreased in outdated and refrigerated PCs compared to conventional PCs. Negative correlation was observed between in vitro anti‐CD62 binding and the fast (R0.5) PLT clearance, but not with delayed (R24 and ST) clearance. In contrast, anti‐GPIbα binding showed positive correlations with delayed but not with fast PLT clearance. Overall (R∑) clearance correlated better with anti‐GPIbα than with anti‐CD62 binding. CD62 density on the PLT surface was decreased after PC transfusion, whereas GPIbα density remained unchanged.CONCLUSION:  These data suggest that CD62 exposure on the PLT surface during PC storage triggers fast CD62‐mediated PC clearance, whereas in vitro GPIbα changes are involved in delayed GPIbα‐mediated PC clearance.
Iron supplementation and 2‐unit red blood cell apheresis: a randomized, double‐blind, placebo‐controlled study
Authors: Radtke Hartmut , Mayer Beate , Röcker Lothar , Salama Abdulgabar , Kiesewetter Holger 
Published: September 2004

BACKGROUND:  The benefits of 2‐unit red blood cell (RBC) apheresis are evident, but iron depletion may be a limiting factor in using this technology. Regular iron supplementation may allow a better utilization of this technique.STUDY DESIGN AND METHODS:  In this study, 260 regular blood donors donated 2‐unit RBCs on each of a total of seven visits at intervals of 8 to 10 weeks. The volunteers were randomly assigned to receive 100 mg of iron(II) or placebo daily. Group A received iron capsules after the first three donations, and Group B after the second three donations, respectively. Hemoglobin, serum ferritin, and serum iron were measured before each donation.RESULTS:  Mean serum ferritin concentration decreased after each donation in the placebo phase of both treatment groups, but it remained largely constant during the iron phase in Group A, and even increased during the iron phase in Group B.CONCLUSION:  Regular iron supplementation prevents iron depletion in the majority of donors after 2‐unit RBC apheresis within an 8‐ to 10‐week period.