In vivo estimation of the short-range stiffness of cross-bridges from joint rotation

Short-range stiffness (SRS) is a mechanical property of muscles that is characterized by a disproportionally high stiffness within a short length range during both lengthening and shortening movements. SRS is attributed to the cross-bridges and is beneficial for stabilizing a joint during, e.g., postural conditions. Thus far, SRS has been estimated mainly on isolated mammalian muscles. In this study we presented a method to estimate SRS in vivo in the human wrist joint.SRS was estimated at joint level in the angular domain (N m/rad) for both flexion and extension rotations of the human wrist in nine healthy subjects. Wrist rotations of 0.15 rad at 3 rad/s were imposed at eight levels of voluntary contraction ranging from 0 to 2.1 N m by means of a single axis manipulator.Flexion and extension SRS of the wrist joint was estimated consistently and accurately using a dynamic nonlinear model that was fitted onto the recorded wrist torque. SRS increased monotonically with torque in a way consistent with previous studies on isolated muscles.It is concluded that in vivo measurement of joint SRS represents the population of coupled cross-bridges in wrist flexor and extensor muscles. In its current form, the presented technique can be used for clinical applications in many neurological and muscular diseases where altered joint torque and (dissociated) joint stiffness are important clinical parameters.     

Évaluation de la sidération myocardique post-effort immédiat par tomoscintigraphie myocardique au 99mTc-sestamibi couplée à l’ECG

AimRepeated episodes of myocardial stunning may lead to chronic ventricular dysfunction. We attempted to assess the parameters related to post-exercise stunning in patients undergoing gated SPECT.MethodsSix hundred patients undergoing a one-day stress/rest ^99mTc-sestamibi gated SPECT were studied. Stress imaging was acquired within 15 minutes after injection. Summed perfusion scores (SSS, SRS and SDS) were calculated using QPS, and LV function assessed using QGS. Stunning was defined as the association of ischemia (SSS ≥ 4 and SDS > 0) and a minimum of 5% decrease in post-stress EF.ResultsIschemia was found in 225 (37.5%) patients. Among these, 67 (30%) showed myocardial stunning. Patients with stunning had a lower rest ESV (47 ± 24 mL vs 65 ± 52 mL, p < 0.0003) and EDV (108 ± 35 mL vs 122 ± 66 mL, p = 0.03), an increased rest LVEF (58 ± 10% vs 52 ± 13%, p < 0.0001) and a decreased post-stress LVEF (49 ± 10% vs 53 ± 13%, p < 0.02) compared to patients with no stunning. The number of myocardial segments showing reversible perfusion defects was increased in patients with stunning (2.7 ± 2.6 vs 1.7 ± 2.1, p < 0.02). On logistic regression, an extent of ischemia greater than two segments and a rest EF greater than 45% were independent predictors of the occurrence of myocardial stunning in patients with ischemia.ConclusionsIn patients with ischemia, exercise-induced stunning was associated with an increased extent of ischemia but also preserved rest ventricular function.     

Multi-channel electromyography during maximal isometric and dynamic contractions

Motor unit behavior differs between contraction types at submaximal contraction levels, however is challenging to study during maximal voluntary contractions (MVCs). With multi-channel surface electromyography (sEMG), mean physiological characteristics of the active motor units can be extracted. Two 8-electrode sEMG arrays were attached on biceps brachii muscle (one on each head) to examine behavior of sEMG variables during isometric, eccentric and concentric MVCs of elbow flexors in 36 volunteers.On average, isometric (364 ± 88 N) and eccentric (353 ± 74 N) MVCs were higher than concentric (290 ± 73 N) MVC (p < 0.001). Mean muscle fiber conduction velocity (CV) was highest during eccentric MVC (4.42 ± 0.49 m/s) than concentric (4.25 ± 0.49 m/s, p < 0.01) and isometric (4.14 ± 0.45 m/s, p < 0.001) MVCs. Furthermore, eccentric MVC showed lower sEMG amplitude at the largest elbow joint angles (120–170°) and higher CV at the smallest (70–150°) elbow joint angles (p < 0.05–0.001) than concentric MVC.The differences in CV and sEMG amplitude between the MVCs suggest that the control strategy of motor units differs between the contraction types during MVCs, and is dependent on the muscle length between the dynamic MVCs.     

Two novel methods to assess ulnar nerve conduction across the elbow

PurposeNerve conduction studies (NCS) are used as an electrodiagnostic method for diagnosing ulnar neuropathy of the elbow (UNE). The purpose of this study was to determine normal and reliability values of across elbow ulnar nerve conduction velocity using two novel methods.MethodsUlnar nerve conduction studies were performed on both upper extremities of 104 healthy subjects. Two different techniques were used to evaluate ulnar nerve function at the elbow: Technique 1 (W-BE-AE) determined mixed NCV across the elbow indirectly while Technique 2 (BE-AE) measured conduction time directly. Twenty subjects returned within one week for re-testing to generate reliability data.ResultsThe mean NCV for the BE-AE segment using Technique 1 was 59.68 m/s (±8.91 m/s). The mean peak latency for the BE-AE segment using Technique 2 was 2.03 ms (±0.24 ms). The interrater and intrarater reliability intraclass correlation coefficient (ICC) for Technique 1 was 0.454 and 0.756, respectively. For Technique 2, the interrater and intrarater reliability ICC was 0.76 and 0.814, respectively.ConclusionThis study identified normal values for ulnar nerve conduction across the elbow with reliability ranging from poor to good, depending on the technique. These two novel techniques provide alternative methods to traditional techniques to measure ulnar nerve conduction across the elbow.     

Electromyographic analysis of upper limb muscles during standardized isotonic and isokinetic robotic exercise of spastic elbow in patients with stroke

Although it has been reported that strengthening exercise in stroke patients is beneficial for their motor recovery, there is little evidence about which exercise method is the better option. The purpose of this study was to compare isotonic and isokinetic exercise by surface electromyography (EMG) analysis using standardized methods.Nine stroke patients performed three sets of isotonic elbow extensions at 30% of their maximal voluntary isometric torque followed by three sets of maximal isokinetic elbow extensions with standardization of mean angular velocity and the total amount of work for each matched set in two strengthening modes. All exercises were done by using 1-DoF planner robot to regulate exact resistive torque and speed. Surface electromyographic activity of eight muscles in the hemiplegic shoulder and elbow was recorded. Normalized root mean square (RMS) values and co-contraction index (CCI) were used for the analysis.The isokinetic mode was shown to activate the agonists of elbow extension more efficiently than the isotonic mode (normalized RMS for pooled triceps: 96.0 ± 17.0 (2nd), 87.8 ± 14.4 (3rd) in isokinetic, 80.9 ± 11.0 (2nd), 81.6 ± 12.4 (3rd) in isotonic contraction, F[1, 8] = 11.168; P = 0.010) without increasing the co-contraction of muscle pairs, implicating spasticity or synergy.     

Electromyographic patterns of lower limb muscles during apprehensive gait in younger and older female adults

ObjectiveInvestigate the influence of apprehensive gait on activation and cocontraction of lower limb muscles of younger and older female adults.MethodsData of 17 younger (21.47 ± 2.06 yr) and 18 older women (65.33 ± 3.14 yr) were considered for this study. Participants walked on the treadmill at two different conditions: normal gait and apprehensive gait. The surface electromyographic signals (EMG) were recorded during both conditions on: rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), tibialis anterior (TA), gastrocnemius lateralis (GL), and soleus (SO).ResultsApprehensive gait promoted greater activation of thigh muscles than normal gait (F = 5.34 and p = 0.007, for significant main effect of condition; RF, p = 0.002; VM, p < 0.001; VL, p = 0.003; and BF, p = 0.001). Older adults had greater cocontraction of knee and ankle stabilizer muscles than younger women (F = 4.05 and p = 0.019, for significant main effect of groups; VM/BF, p = 0.010; TA/GL, p = 0.007; and TA/SO, p = 0.002).ConclusionApprehensive gait promoted greater activation of thigh muscles and older adults had greater cocontraction of knee and ankle stabilizer muscles. Thus, apprehensive gait may leads to increased percentage of neuromuscular capacity, which is associated with greater cocontraction and contribute to the onset of fatigue and increased risk of falling in older people.     

Impaired action potential conduction at high force levels after eccentric exercise

High-density surface electromyography was used to examine whether gross sarcolemmal function is impaired in m. biceps brachii after intensive eccentric elbow flexor exercise, when measured at wide range of isometric contraction levels.Root mean square (RMS), mean power frequency (MNF) and mean muscle fibre conduction velocity (CV) were calculated before and up to four days post-exercise.Maximal isometric voluntary (MVC) force decreased by 21.3 ± 5.6% two hours after exercise, and by 12.6 ± 11.1% two days post-exercise. CV and MNF decreased both during MVC (CV from 4.1 ± 0.3 m/s to 3.8 ± 0.4 m/s and MNF from 92.6 ± 10 Hz to 85.2 ± 11 Hz) and during electrically evoked maximal M-wave (CV from 4.1 ± 0.3 m/s to 3.0 ± 0.5 m/s and MNF from 97.1 ± 27.2 Hz to 78.0 ± 24.4 Hz) two hours post-exercise. Furthermore, at submaximal isometric force levels, CV and MNF decreased only at higher contraction levels (40%, 50% and 75% of MVC) two hour post-exercise.It can be concluded that intensive exercise can temporarily impair gross sarcolemmal function. In addition, since this only occurred at high force levels, based on Henneman’s size principle, it seems that higher threshold motor units were predominantly affected.     

Atrioventricular nodal function during atrial fibrillation: Model building and robust estimation

Statistical modeling of atrioventricular (AV) nodal function during atrial fibrillation (AF) is revisited for the purpose of defining model properties and improving parameter estimation. The characterization of AV nodal pathways is made more detailed and the number of pathways is now determined by the Bayesian information criterion, rather than just producing a probability as was previously done. Robust estimation of the shorter refractory period (i.e., of the slow pathway) is accomplished by a Hough-based technique which is applied to a Poincaré plot of RR intervals. The performance is evaluated on simulated data as well as on ECG data acquired from AF patients during rest and head-up tilt test. The simulation results suggest that the refractory period of the slow pathway can be accurately estimated even in the presence of many artifacts. They also show that the number of pathways can be accurately determined. The results from ECG data show that the refined AV node model provides significantly better fit than did the original model, increasing from 85 ± 5% to 88 ± 4% during rest, and from 86 ± 5% to 87 ± 3% during tilt. When assessing the effect of sympathetic stimulation, the AF frequency increased significantly during tilt (6.25 ± 0.58 Hz vs. 6.32 ± 0.61 Hz, p < 0.05, rest vs. tilt) and the prolongation of the refractory periods of both pathways decreased significantly (slow pathway: 0.23 ± 0.20 s vs. 0.11 ± 0.10 s, p < 0.001, rest vs. tilt; fast pathway: 0.24 ± 0.31 s vs. 0.16 ± 0.19 s, p < 0.05, rest vs. tilt). The results show that AV node characteristics can be assessed noninvasively for the purpose of quantifying changes induced by autonomic stimulation.     

Descriptive analysis of kinematics and kinetics of catchers throwing to second base from their knees

In order to decrease the amount of time that it takes the catcher to throw the ball, a catcher may chose to throw from the knees. Upper extremity kinematics may play a significant role in the kinetics about the elbow observed in catchers throwing from the knees. If relationships between kinematics and kinetics exist then the development of training and coaching instruction may help in reduced upper extremity injury risk. Twenty-two baseball and softball catchers (14.36 ± 3.86 years; 165.11 ± 17.54 cm; 65.67 ± 20.60 kg) volunteered. The catchers exhibited a less trunk rotation (5.6 ± 16.2°), greater elbow flexion (87.9 ± 21.4°) and decreased humeral elevation (71.1 ± 12.3°) at the event of maximum shoulder external rotation as compared to what has previously reported in catchers. These variables are important, as they have previously been established as potential injury risk factors in pitchers, however it is not yet clear the role these variables play in catchers’ risk of injury. A positive relationship between elbow varus torque during the deceleration phase and elbow flexion at MIR was observed (r = 0.609; p = 0.003). Throwing from the knees reduces a catcher’s ability to utilize the proximal kinetic chain and this may help to explain why their kinematics and kinetics differ from what has previously been presented in the literature.     

Biceps brachii can add to performance of tasks requiring supination in cerebral palsy patients

The aim of this study was to assess whether cerebral palsy patients can use biceps brachii for supination during movement tasks requiring supination and pronation. 3D upper extremity kinematic and EMG-data of 12 patients (mean age 13 y 8 mo ± 36 mo) were compared to 10 healthy age-matched controls. Significant difference in biceps brachii activation between maximal isolated pronation and supination in both groups showed that it is possible for CP patients to use biceps brachii for supination. Performance of reach-to-grasp with either pronation or supination showed similar activation patterns as during isolated tasks in both groups, although increased biceps brachii activation likely also hampered performance of reach-to-grasp in the patient group by causing increased, and possibly unwanted elbow flexion. However, the functional effect of this flexion for supination purposes cannot be ruled out. Therefore, one should be cautious with simply weakening biceps brachii when the purpose is to improve functional reach. Ideally treatment might focus more on changing the flexion moment/supination moment ratio of biceps toward a stronger supination function.     

Posture-movement changes following repetitive motion-induced shoulder muscle fatigue

Repetitive motion-induced fatigue not only alters local motion characteristics but also provokes global reorganization of movement. However, the three-dimensional (3D) characteristics of these reorganization patterns have never been documented in detail. The goal of this study was to assess the effects of repetitive reaching-induced arm fatigue on the whole-body, 3D biomechanical task characteristics. Healthy subjects (N = 14) stood and performed a continuous reaching task (RRT) between two targets placed at shoulder height to fatigue. Whole-body kinematic (Vicon^©), kinetic (AMTI^© force platforms) and electromyographic (EMG, Noraxon^©) characteristics were recorded. Maximal voluntary isometric efforts (MVIE) of the shoulder and elbow were measured pre- and post-RRT. Post-RRT shoulder elevation MVIE was reduced by 4.9 ± 8.3% and trapezius EMG amplitude recorded during the RRT increased by 46.9 ± 49.9% from the first to last minute of the RRT, indicating that arm fatigue was effectively induced. During fatigued reaching, subjects elevated their shoulder (11.7 ± 10.5 mm) and decreased their average shoulder abduction angle by 8.3 ± 4.4°. These changes were accompanied by a lateral shift of the body’s center of mass towards the non-reaching arm. These findings suggest a compensatory strategy to decrease the load on the fatigued shoulder musculature.     

Influence of additional load on the moments of the agonist and antagonist muscle groups at the knee joint during closed chain exercise

The present study investigated the influence of additional loads on the knee net joint moment, flexor and extensor muscle group moments, and cocontraction index during a closed chain exercise. Loads of 8, 28, or 48 kg (i.e., respectively, 11.1 ± 1.5%, 38.8 ± 5.3%, and 66.4 ± 9.0% of body mass) were added to subjects during dynamic half squats. The flexor and extensor muscular moments and the amount of cocontraction were estimated at the knee joint using an EMG-and-optimization model that includes kinematics, ground reaction, and EMG measurements as inputs. In general, our results showed a significant influence of the Load factor on the net knee joint moment, the extensor muscular moment, and the flexor muscle group moment (all Anova p < .05). Hence we confirmed an increase in muscle moments with increasing load and moreover, we also showed an original “more than proportional” evolution of the flexor and extensor muscle group moments relative to the knee net joint moment. An influence of the Phase (i.e., descent vs. ascent) factor was also seen, revealing different activation strategies from the central nervous system depending on the mode of contraction of the agonist muscle group. The results of the present work could find applications in clinical fields, especially for rehabilitation protocols.     

Active immunization against inhibin-based peptides to increase ovulation rate in non-prolific Malpura ewes

The aim of this study was to explore the possibility of increasing the ovulation rate of Malpura, a non-prolific tropical breed of sheep by immunization against inhibin-based peptide immunogens. Ewes were divided into three groups (n = 5 each) and actively immunized against the synthetic peptides from the α_C [bIα(1–29)-Tyr³⁰] or α_N [bI-₄₃-Tyr¹⁵²(153–167)Cys¹⁶⁸] area of the bovine inhibin α-subunit conjugated to ovalbumin or against ovalbumin (control). Each ewe received a primary immunization of 400 μg immunogen and 3 boosters, each of 200 μg immunogen at 4-week intervals. Estrus was synchronized using a double PGF₂α injection schedule and laparoscopy was performed after each estrus to determine the ovulation response. Immunization against both the peptides did not affect the interval from PGF treatment to the onset of estrus, the duration of estrus and the number of large unovulated follicles. In contrast to the complete absence of multiple ovulations in the controls, all the ewes immunized against α_C or α_N peptides showed multiple ovulations (range 2–7) in all the three estrous cycles evaluated, except for one ewe immunized against the α_N peptide, which exhibited multiple ovulations in only 1 out of the 3 estrous cycles. Compared to that of the controls (1.0 ± 0.9, 1.0 ± 0.0 and 0.6 ± 0.2, respectively), the mean ovulation rate was higher (P < 0.01) in the ewes immunized against the αC (4.8 ± 1.02, 5.0 ± 1.05 and 5.0 ± 0.45, respectively) or against αN (4.5 ± 1.19, 2.5 ± 0.87 and 2.7 ± 0.75, respectively, P < 0.05) peptide in estrous cycles numbers 1, 2 and 3. These results show that active immunization against inhibin-based peptide immunogens is effective in increasing ovulation rate in Malpura, a non-prolific breed of sheep and that it may be an alternative to conventional superovulation regimes.     

Validity of resting myotonometric assessment of lower extremity muscles in chronic stroke patients with limited hypertonia: A preliminary study

The aim of this preliminary study was to examine the validity of a recently-introduced tool (MyotonPRO) for the assessment of mechanical parameters of the main lower extremity muscles in patients with chronic stroke. Thigh and shank muscles of 20 stroke patients with limited hypertonia (11 men and 9 women; mean age: 52 ± 11 yrs) and 20 healthy controls (11 men and 9 women; mean age: 53 ± 10 yrs) were bilaterally evaluated with (i) MyotonPRO for muscle stiffness, tone and elasticity, (ii) ultrasonography for muscle and subcutaneous thickness, and (iii) dynamometry for isometric muscle strength. MyotonPRO parameters of stroke patients were reassessed a week later (inter-day test-retest design). For all the investigated muscles, MyotonPRO variables did not differ between the more affected and the less affected side of patients (P > 0.05 for main side effect), and neither differed between patients and controls (P > 0.05 for main group effect), except for gastrocnemius medialis stiffness that was higher in patients (300 ± 51 N/m) than in controls (281 ± 29 N/m; P < 0.05). Thigh muscle stiffness was negatively correlated to subcutaneous thickness (r = −0.84 for the vastus lateralis; P < 0.001), while only tibialis anterior stiffness and tone correlated positively with muscle thickness (both r = 0.46; P < 0.01). Test-retest reliability of MyotonPRO parameters was adequate, except for muscle elasticity. The validity of MyotonPRO for the evaluation of thigh muscles in chronic stroke patients is partially challenged by the poor discriminant ability and by the considerable impact of subcutaneous tissue thickness (sex-dependent) on mechanical parameters. The potential validity of MyotonPRO for the assessment of shank muscles requires further investigation.     

Menstrual Disorders and Androgen-Related Traits in Young Women with Type 1 Diabetes Mellitus: a Clinical Study

Objective: To investigate possible causes of menstrual disorders and androgen-related traits in young women with type 1 diabetes mellitus (T1DM).Methods: Fifty-three women with T1DM (duration 8.0 ± 5.6 years), 41 women with (polycystic ovary syndrome) PCOS, and 51 controls matched for age (19.4 ± 4.3 years vs. 21.2 ± 2.7 years vs. 20.8 ± 3.1 years; P>.05) and body mass index (BMI) (22.2 ± 2.7 kg/m² vs. 21.9 ± 2.0 kg/m² vs. 21.4 ± 1.9 kg/m²; P>.05) were prospectively recruited.Results: Two women (3.8%) in the T1DM group had not experienced menarche (at 15.5 and 16.6 years); of the rest, 23.5% had oligomenorrhea, 32.1% hirsutism, and 45.3% had acne. The age at menarche was delayed in the T1DM group compared to controls (12.7 ± 1.3 vs. 12.0 ± 1.0 years; P = .004), while no difference was observed with the polycystic ovary syndrome (PCOS) group (12.4 ± 1.2 years). There were no differences in total testosterone (0.43 ± 0.14 ng/mL vs. 0.39 ± 0.14 ng/mL; P>.05), dehydroepiandrosterone sulfate (DHEA-S) (269 ± 112 μg/dL vs. 238 ± 106 μg/dL; P>.05) or Δ4-androstenedione (2.4 ± 1.3 ng/mL vs. 1.9 ± 0.5 ng/mL; P>.05) concentrations between T1DM and controls. However, patients with T1DM had lower sex hormone binding globulin (SHBG) concentrations than controls (61 ± 17 nmol/L vs. 83 ± 18.1 nmol/L; P = .001), which were even lower in the PCOS group (39.5 ± 12.9 nmol/L; P = .001 compared with T1DM). The free androgen index (FAI) was higher in the PCOS group compared with both other groups (T1DM vs. PCOS vs. controls: 2.53 ± 0.54 vs. 7.88 ± 1.21 vs. 1.6 ± 0.68; P<.001). FAI was higher in patients with T1DM compared to controls as well (P = .038). There was no difference in DHEA-S concentrations between T1DM and PCOS patients (269 ± 112 μg/dL vs. 297 ± 100 μg/dL; P>.05).Conclusion: Menstrual disorders and androgen-related traits in young women with T1DM may be attributed to an increase in androgen bioavailability due to decreased SHBG concentrations.     

Performances diagnostiques des tomoscintigraphies myocardiques de stress,réalisées avec une caméra à semi-conducteurs et un protocole très faible dose

IntroductionThis retrospective study aimed to assess the performances in the detection of coronary artery disease patients of the stress myocardial perfusion imaging (MPI) performed with a semiconductor camera, a very low dose stress-rest protocol and short recording times.Material and methodsWe analyzed consecutive MPI exams, which has been routinely planed with the “D-SPECT” semiconductor camera, a 1-day stress-rest protocol, very low doses of Sestamibi-^99mTc (120 MBq at stress and 360 MBq at rest for a 75 kg body weight patient) and short acquisition-times targeting the recording of 500 myocardial kcounts (on average, 8 min for stress and 3 min for rest). The ability to detect coronary artery stenosis (> 50% diameter reduction) was assessed in a group of 118 patients, who had coronary angiography at ≤ 3 months from MPI, and normalcy rate was assessed in a group of 74 patients showing a low pretest probability of coronary artery disease (< 10%).ResultsSensitivity, positive predictive value and global accuracy for identifying the 81 patients with ≥ 1 coronary artery stenosis were 85%, 83% and 78%, respectively; and normalcy rate was 96%. Mean effective doses were: (1) 4.9 ± 1.4 mSv in the group with coronary angiography and where most exams (90%) comprised both stress and rest MPI; and (2) 1.9 ± 1.5 mSv in the low probability group and where most exams (70%) comprised only stress MPI.ConclusionWhen performed with a sensitive semiconductor camera and a very low dose stress-rest protocol, MPI provides high diagnostic performances, equivalent to those documented with conventional cameras in the same study setting, but with dramatic reduction of patients’ radiation.     

The range of axial rotation of the glenohumeral joint

There is a paucity of data in the literature on the restraining effects of the glenohumeral (GH) ligaments; cadaveric testing is one of the best methods for determining the function of these types of tissues. The aim of this work was to commission a custom-made six degrees of freedom (dof) joint loading apparatus and to establish a protocol for laxity testing of cadaveric shoulder specimens. Nine cadaveric shoulder specimens were used in this study and each specimen had all muscle resected leaving the scapula, humerus (transected at mid-shaft) and GH capsule. Specimens were mounted on the testing apparatus with the joint in the neutral position and at 30°, 60° and 90° GH abduction in the coronal, scapula and 30° forward flexion planes. For each orientation, 0–1 N m in 0.1 N m increments was applied in internal/external rotation and the angular displacement recorded. The toe-region of the moment–displacement curves ended at approximately ±0.5 N m. The highest rotational range of motion for the joint was 140° for ±1.0 N m at 30° GH abduction in the scapula plane. The range of motion shifted towards external rotation with increasing levels of abduction. The results provide the optimum loading regime to pre-condition shoulder specimens and minimise viscoelastic effects in the ligaments prior to laxity testing (>0.5 N m at 30° GH abduction in any of the three planes). Knowledge of the mechanical properties of the GH capsuloligamentous complex has implications for modelling of the shoulder as well surgical planning and intervention.     

Free radical scavenging activity from different extracts of leaves of Bauhinia vahlii Wight & Arn.

The objectives of this study were to determine phenolic content and antioxidant activities of chloroform, acetone, methanol and hot water extracts of Bauhinia vahlii leaves. The hot water extract afforded the highest yield (6.3%) while the lowest yield was obtained from the chloroform extract (2.1%). The methanol extract contains higher levels of total phenolics (48.7 ± 0.7 g GAE/100 g extract), tannins (21.7 ± 0.7 g GAE/100 g extract) and flavonoids (10.3 ± 0.2 RE/100 g extract). The extracts were subjected to assess their antioxidant potential using various in vitro systems such as DPPH, ABTS⁺, FRAP, OH, β-carotene linoleic acid bleaching system, phosphomolybdenum reduction and Fe²⁺ chelation. It is concluded that the methanolic extract of B. vahlii leaves have strong antioxidant potential. Further study is necessary for isolation and characterization of the active antioxidants, which may serve as a potential source of natural antioxidants.     

Évaluation de la fonction ventriculaire gauche par l’utilisation d’une caméra à semi-conducteur Cadmium Zinc Telluride (CZT) : impact de l’échantillonnage temporel (8 vs 16 intervalles)

BackgroundNew CZT cameras provide an increased spatial resolution and sensitivity. The tomographic acquisition “in list mode” allows the evaluation of the left ventricular function using 8–16 intervals per cycle with an increased spatial resolution. However, the impact of temporal sampling on evaluation of the contractile function remains uncertain.Method^99mTc-sestamibi SPECT studies were acquired in 99 consecutive patients (70 men, 29 women) using an ultrafast CZT Camera (D-Spectrum, Spectrum Dynamics) and processed using both 8- and 16-interval (int). All patients underwent a stress (2 MBq/kg)-rest (6 MBq/kg) single day (stop condition: 700 KCTS within a myocardial VOI). Left ventricular function was assessed using QGS^®. Perfusion was analyzed using QPS^® and quantified using Summed Stress Score (SSS), Summed Rest Score (SRS) and Summed Difference Score (SDS) (17 segments model) and the extent of perfusion defects (% of LV).ResultsEight intervals gating overestimated the end-systolic volumes (ESV) and underestimated the left ventricular ejection fraction (LVEF) compared to 16 intervals (respectively for eight and 16 intervals: at rest [VTS: 45 ± 25 mL vs 41 ± 24 mL, P < 0.0001, LVEF: 53 ± 10% vs 59 ± 10%, P < 0.0001], and post-stress [VTS: 43 ± 24. mL vs 39 ± 24 mL, P < 0.0001; LVEF: 58 ± 10% vs 61 ± 11%, P < 0.0001]). However, it was not found significant differences between end diastolic volumes (EDV) (at rest: EDV: 98 ± 33 mL vs 97 ± 33 mL, P = NS; and post-stress: EDV: 98 ± 33 ml vs 99 ± 34 mL, P = NS). Parameters of left ventricular function were consistent between eight and 16 intervals (EDV: CCC = 0.99, ESV: CCC = 0.98, LVEF: CCC = 0.92, P < 0.0001). Correlation could not be evidenced between the extent of perfusion defect and the difference between eight and 16 intervals for the different parameters of left ventricular function both at rest and post-stress.ConclusionIn our study, comparison between eight and 16 intervals showed an overestimation of the ESV and an underestimation of LVEF, without correlation with perfusion abnormalities. The estimation of LVEF on CZT camera should take into account the chosen temporal sampling.     

Increased plasma levels of osteopontin are associated with activation of the renin–aldosterone system and with myocardial and coronary microvascular damage in dilated cardiomyopathy

In patients with dilated cardiomyopathy (DCM) abnormal myocardial blood flow (MBF) has been associated with coronary microvascular dysfunction. The aim of this study was to test the hypothesis that osteopontin (OPN) plasma levels could be associated with the activation of the renin–aldosterone system (RAS) in these patients and be involved in mediating myocardial and coronary damage. In 66 patients with idiopathic left ventricular dysfunction of variable severity the plasma levels of OPN were correlated with biomarkers of systemic metabolism, RAS activation, myocardial dysfunction and with clinical indexes of left ventricle (LV) function and perfusion obtained by 2D-echocardiography and PET. As compared to controls, patients showed a significant increase of inflammatory markers (OPN: 508 ± 30.8 ng/ml vs. 426.9 ± 16.4, p < 0.05 and interleukin (IL)-6: 1.71 ± 0.29 pg/ml vs. 0.38 ± 0.03 pg/ml, p < 0.001) and of indexes of cardiac damage. OPN levels were significantly correlated with the extent of microvascular dysfunction (MBF at rest: p = 0.01; during dipyridamole: p = 0.0003) and with plasma renin activity (PRA) (r = 0.26, p = 0.04). Both in patients with milder or more severe LV dysfunction lower MBF values were associated with higher OPN levels and PRA. These results suggest a interdependent role of RAS and vascular inflammation in cardiomyopathy.