In Vivo Measurements of Moment Arm Lengths of Three Elbow Flexors at Rest and During Isometric Contractions

2012 ◽  
Vol 28 (1) ◽  
pp. 63-69 ◽  
Author(s):  
Ryota Akagi ◽  
Soichiro Iwanuma ◽  
Satoru Hashizume ◽  
Hiroaki Kanehisa ◽  
Toshimasa Yanai ◽  
...  
Keyword(s):  
Biceps Brachii ◽  
Elbow Flexion ◽  
Isometric Contractions ◽  
Elbow Flexors ◽  
Moment Arm ◽  
Resonance Imaging ◽  
Intensity Dependence ◽  
In Vivo Measurements ◽  
The Right

The purpose of this study was to determine in vivo moment arm lengths (MAs) of three elbow flexors at rest and during low- and relatively high-intensity contractions, and to examine the contraction intensity dependence of MAs at different joint positions. At 50°, 80° and 110° of elbow flexion, MAs of the biceps brachii, brachialis and brachioradialis were measured in 10 young men using sagittal images of the right arm obtained by magnetic resonance imaging, at rest and during 20% and 60% of isometric maximal voluntary elbow flexion. In most conditions, MAs increased with isometric contractions, which is presumably due to the contraction-induced thickening of the muscles. This phenomenon was especially evident in the flexed elbow positions. The influence of the contraction intensities on the increases in MAs varied across the muscles. These results suggest that in vivo measurements of each elbow flexor MA during contractions are essential to properly examine the effects on the interrelationships between elbow flexion torque and individual muscle forces.

scholarly journals Alteration within the Hippocampal Volume in Patients with LHON Disease—7 Tesla MRI Study

2020 ◽  
Vol 10 (1) ◽  
pp. 14
Author(s):  
Cezary Grochowski ◽  
Kamil Jonak ◽  
Marcin Maciejewski ◽  
Andrzej Stępniewski ◽  
Mansur Rahnama-Hezavah
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Molecular Layer ◽  
Three Dimensional ◽  
Hippocampal Volume ◽  
7 Tesla ◽  
Diagnostic Process ◽  
Resonance Imaging ◽  
The Right

Purpose: The aim of this study was to assess the volumetry of the hippocampus in the Leber’s hereditary optic neuropathy (LHON) of blind patients. Methods: A total of 25 patients with LHON were randomly included into the study from the national health database. A total of 15 patients were selected according to the inclusion criteria. The submillimeter segmentation of the hippocampus was based on three-dimensional spoiled gradient recalled acquisition in steady state (3D-SPGR) BRAVO 7T magnetic resonance imaging (MRI) protocol. Results: Statistical analysis revealed that compared to healthy controls (HC), LHON subjects had multiple significant differences only in the right hippocampus, including a significantly higher volume of hippocampal tail (p = 0.009), subiculum body (p = 0.018), CA1 body (p = 0.002), hippocampal fissure (p = 0.046), molecular layer hippocampus (HP) body (p = 0.014), CA3 body (p = 0.006), Granule Cell (GC) and Molecular Layer (ML) of the Dentate Gyrus (DG)–GC ML DG body (p = 0.003), CA4 body (p = 0.001), whole hippocampal body (p = 0.018), and the whole hippocampus volume (p = 0.023). Discussion: The ultra-high-field magnetic resonance imaging allowed hippocampus quality visualization and analysis, serving as a powerful in vivo diagnostic tool in the diagnostic process and LHON disease course assessment. The study confirmed previous reports regarding volumetry of hippocampus in blind individuals.

scholarly journals ECG-gated dynamic magnetic resonance imaging method for examination of the pig heart

2001 ◽  
Vol 49 (3) ◽  
pp. 275-284
Author(s):  
Zs. Petrási ◽  
R. Romvári ◽  
G. Bajzik ◽  
B. Fenyves ◽  
I. Repa ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Three Dimensional ◽  
Dynamic Magnetic Resonance Imaging ◽  
Imaging Method ◽  
Resonance Imaging ◽  
Dynamic Magnetic Resonance ◽  
Heart Cycle ◽  
The Right

A dynamic magnetic resonance imaging (MRI) method was developed for in vivo examination of the pig heart. Measurements were carried out on 15 meat-type pigs of different liveweight using a 1.5 T equipment. Inhalation anaesthesia was applied, then data acquisition was synchronised by ECG gating. Depending on the heart rate and heart size, in each case 8 to 10 slices and in each slice 8 to 14 phases were acquired prospectively according to one heart cycle. During the post-processing of the images the left and the right ventricular volumes were determined. The values measured at 106 kg liveweight are 2.5 times higher than those obtained at 22 kg, while the ejection fractions are equal. The calculated cardiac output values were 3.5 l (22 kg, 132 beats/min.), and 6.0 l (106 kg, 91 beats/min.), respectively. After measuring the wall thickness, the contraction values were also determined for the septum (70%), and for the anterior (61%), posterior (41%) and lateral (54%) walls of the left ventricle. Three-dimensional animated models of the ventricles were constructed. Based on the investigations performed, the preconditioning, the anaesthetic procedure, the specific details of ECG measurement and the correct MR imaging technique were worked out.

In Vivo MR Studies of Dynamic Changes in the Interosseous Membrane of the Forearm During Rotation

1999 ◽  
Vol 24 (2) ◽  
pp. 245-248 ◽  
Author(s):  
T. NAKAMURA ◽  
Y. YABE ◽  
Y. HORIUCHI
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Interosseous Membrane ◽  
Resonance Imaging ◽  
Forearm Rotation ◽  
Dynamic Changes ◽  
Magnetic Resonance Imaging Mri ◽  
Membranous Part ◽  
The Right

In vivo dynamic changes in the interosseous membrane (IOM) during forearm rotation were studied using magnetic resonance imaging (MRI). The right forearms of 20 healthy volunteers were examined in five different rotational positions. Axial slices were obtained at the proximal quarter, the middle and the distal quarter of the forearm. The changes in shape of the IOM during rotation were observed in an axial MR plane. For each image, we measured the interosseous distance and the length of the interosseous membrane. Images of the tendinous and membranous parts of the IOM could be differentiated by thickness. There were minimal dynamic changes in the tendinous part on the MRI while the membranous part showed numerous changes during rotation. The interosseous distance and the length of the interosseous membrane were maximum from a neutral to a slightly supinated position. The tendinous part is considered to be taut during rotation to provide stability between the radius and the ulna, but the membranous part which is soft, thin and elastic, allows smooth rotation.

scholarly journals Normal kinematics of the upper cervical spine during the Flexion–Rotation Test – In vivo measurements using magnetic resonance imaging

2011 ◽  
Vol 16 (2) ◽  
pp. 167-171 ◽  
Author(s):  
Hiroshi Takasaki ◽  
Toby Hall ◽  
Sadanori Oshiro ◽  
Shouta Kaneko ◽  
Yoshikazu Ikemoto ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cervical Spine ◽  
Magnetic Resonance ◽  
Upper Cervical Spine ◽  
Resonance Imaging ◽  
Rotation Test ◽  
In Vivo Measurements ◽  
Upper Cervical

scholarly journals In vivo measurements of kidney glomerular number and size in healthy and Os/+ mice using MRI

2019 ◽  
Vol 317 (4) ◽  
pp. F865-F873 ◽  
Author(s):  
Edwin J. Baldelomar ◽  
Jennifer R. Charlton ◽  
Kimberly A. deRonde ◽  
Kevin M. Bennett
Keyword(s):  
Ex Vivo ◽  
Nephron Number ◽  
Wild Type ◽  
Resonance Imaging ◽  
Renal Hypoplasia ◽  
Nephron Endowment ◽  
In Vivo Measurements ◽  
Glomerular Number ◽  
Direct Measurements

The development of chronic kidney disease (CKD) is associated with the loss of functional nephrons. However, there are no methods to directly measure nephron number in living subjects. Thus, there are no methods to track the early stages of progressive CKD before changes in total renal function. In this work, we used cationic ferritin-enhanced magnetic resonance imaging (CFE-MRI) to enable measurements of glomerular number ( Nglom) and apparent glomerular volume (aVglom) in vivo in healthy wild-type (WT) mice ( n = 4) and mice with oligosyndactylism (Os/+; n = 4), a model of congenital renal hypoplasia leading to nephron reduction. We validated in vivo measurements of Nglom and aVglom by high-resolution ex vivo MRI. CFE-MRI measured a mean Nglom of 12,220 ± 2,028 and 6,848 ± 1,676 (means ± SD) for WT and Os/+ mouse kidneys in vivo, respectively. Nglom measured in all mice in vivo using CFE-MRI varied by an average 15% from Nglom measured ex vivo in the same kidney (α = 0.05, P = 0.67). To confirm that CFE-MRI can also be used to track nephron endowment longitudinally, a WT mouse was imaged three times by CFE-MRI over 2 wk. Values of Nglom measured in vivo in the same kidney varied within ~3%. Values of aVglom calculated from CFE-MRI in vivo were significantly different (~15% on average, P < 0.01) from those measured ex vivo, warranting further investigation. This is the first report of direct measurements of Nglom and aVglom in healthy and diseased mice in vivo.

scholarly journals Ipsilateral corticomotor responses are confined to the homologous muscle following cross-education of muscular strength

2018 ◽  
Vol 43 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Joel Mason ◽  
Ashlyn K. Frazer ◽  
Deanna M. Horvath ◽  
Alan J. Pearce ◽  
Janne Avela ◽  
...  
Keyword(s):  
Strength Training ◽  
Muscular Strength ◽  
Biceps Brachii ◽  
Control Group ◽  
Elbow Flexors ◽  
Corticomotor Excitability ◽  
Flexor Carpi Radialis ◽  
Cross Education ◽  
The Right ◽  
Wrist Flexors

Cross-education of strength occurs when strength-training 1 limb increases the strength of the untrained limb and is restricted to the untrained homologous muscle. Cortical circuits located ipsilateral to the trained limb might be involved. We used transcranial magnetic stimulation (TMS) to determine the corticomotor responses from the untrained homologous (biceps brachii) and nonhomologous (flexor carpi radialis) muscle following strength-training of the right elbow flexors. Motor evoked potentials were recorded from the untrained left biceps brachii and flexor carpi radialis during a submaximal contraction from 20 individuals (10 women, 10 men; aged 18–35 years; training group, n = 10; control group, n = 10) before and after 3 weeks of strength-training the right biceps brachii at 80% of 1-repetition maximum. Recruitment-curves for corticomotor excitability and inhibition of the untrained homologous and nonhomologous muscle were constructed and assessed by examining the area under the recruitment curve. Strength-training increased strength of the trained elbow flexors (29%), resulting in an 18% increase in contralateral strength of the untrained elbow flexors (P < 0.0001). The trained wrist flexors increased by 19%, resulting in a 12% increase in strength of the untrained wrist flexors (P = 0.005). TMS showed increased corticomotor excitability and decreased corticomotor inhibition for the untrained homologous muscle (P < 0.05); however, there were no changes in the untrained nonhomologous muscle (P > 0.05). These findings show that the cross-education of muscular strength is spatially distributed; however, the neural adaptations are confined to the motor pathway ipsilateral to the untrained homologous agonist.

Magnetite/dextran-functionalized graphene oxide nanosheets for in vivo positive contrast magnetic resonance imaging

RSC Advances ◽  
2015 ◽  
Vol 5 (59) ◽  
pp. 47529-47537 ◽  
Author(s):  
S. Moradi ◽  
O. Akhavan ◽  
A. Tayyebi ◽  
R. Rahighi ◽  
M. Mohammadzadeh ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Graphene Oxide ◽  
Positive Contrast ◽  
Functionalized Graphene ◽  
Resonance Imaging ◽  
Graphene Oxide Nanosheets ◽  
Functionalized Graphene Oxide ◽  
Contrast Magnetic Resonance ◽  
The Right

In vivo positive contrast MRI by magnetite/dextran-functionalized graphene oxide (SPIO-Dex-FGO) as compared to Magnevist® (the right rat).

Sequence of Preparatory Set for Response Movement

1988 ◽  
Vol 66 (2) ◽  
pp. 515-520 ◽  
Author(s):  
Takashi Kinugasa ◽  
Keisuke Fukuda ◽  
Ryuichi Nakamura ◽  
Toru Hosokawa
Keyword(s):  
Biceps Brachii ◽  
Reaction Times ◽  
Movement Patterns ◽  
Warning Signal ◽  
Elbow Flexion ◽  
Preparatory Set ◽  
The Subject ◽  
The Difference ◽  
The Right ◽  
Simple Rt

Electromyographic reaction times (EMG-RTs) of the right biceps brachii muscle were examined for two movement patterns, elbow flexion and forearm supination, in 8 healthy male subjects under simple and complex RT conditions with varied preparatory intervals (PIs): 0, 200, 400, 600, and 800 msec. In the simple RT condition, the subject was informed of the movement patterns to be performed prior to beginning the trials. In the complex RT condition the subject had to choose one of the two movement patterns at the time of the presentation of a warning signal. The results indicated that: (1) compared with the simple RT condition a delay of about 100 msec. in over-all mean EMG-RT was observed at PI = 0 msec. in the complex RT condition; (2) the difference of over-all mean EMG-RT between the two RT conditions disappeared when PI = 400 msec.; and (3) the difference in EMG-RTs between flexion and supination in the complex RT condition became the same as that in the simple RT condition when PI = 700 msec. It is assumed that the preparatory set for response movements is organized in an order, resulting in the differentiation of RT.

scholarly journals Electrical nerve stimulation modulates motor unit activity in contralateral biceps brachii during steady isometric contractions

2018 ◽  
Vol 120 (5) ◽  
pp. 2603-2613 ◽  
Author(s):  
Landon D. Hamilton ◽  
Diba Mani ◽  
Awad M. Almuklass ◽  
Leah A. Davis ◽  
Taian Vieira ◽  
...  
Keyword(s):  
Motor Unit ◽  
Pulse Duration ◽  
Nerve Stimulation ◽  
Unit Activity ◽  
Biceps Brachii ◽  
Elbow Flexors ◽  
Stimulus Pulse ◽  
Electrical Nerve Stimulation ◽  
Motor Unit Activity ◽  
The Right

The purpose of our study was to compare the influence of five types of electrical nerve stimulation delivered through electrodes placed over the right biceps brachii on motor unit activity in the left biceps brachii during an ongoing steady isometric contraction. The electrical stimulation protocols comprised different combinations of pulse duration (0.2 and 1.0 ms), stimulus frequency (50 and 90 Hz), and stimulus current (greater or less than motor threshold). The electrical nerve stimulation protocols were applied over the muscle of the right elbow flexors of 13 participants (26 ± 3 yr) while they performed voluntary contractions with the left elbow flexors to match a target force set at 10% of maximum. All five types of electrical nerve stimulation increased the absolute amplitude of the electromyographic (EMG) signal recorded from the left biceps brachii with high-density electrodes. Moreover, one stimulation condition (1 ms, 90 Hz) had a consistent influence on the centroid location of the EMG amplitude distribution and the average force exerted by the left elbow flexors. Another stimulation condition (0.2 ms, 90 Hz) reduced the coefficient of variation for force during the voluntary contraction, and both low-frequency conditions (50 Hz) increased the duration of the mean interspike interval of motor unit action potentials after the stimulation had ended. The findings indicate that the contralateral effects of electrical nerve stimulation on the motor neuron pool innervating the homologous muscle can be influenced by both stimulus pulse duration and stimulus frequency. NEW & NOTEWORTHY Different types of electrical nerve stimulation delivered through electrodes placed over the right biceps brachii modulated the ongoing motor unit activity in the left biceps brachii. Although the effects varied with stimulus pulse duration, frequency, and current, all five types of electrical nerve stimulation increased the amplitude of the electromyographic activity in the left biceps brachii. Moreover, most of the effects in the left arm occurred after the electrical nerve stimulation of the right arm had been terminated.

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