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91.
Guzman-Lopez J Buisson Y Strutton PH Bronstein AM 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2011,214(1):37-45
We investigated the interaction between vestibular and corticospinal stimuli in 8 healthy volunteers. Vestibular stimulation
was induced with unilateral ear caloric irrigation (30°C) with subjects supine. Single transcranial magnetic stimulation (TMS)
pulses were delivered (double-cone coil, intensities 60–75% maximal output) every 10–20 s during vestibular activation and
during baseline. Bilateral surface electromyography (EMG) from splenius capitis, sternocleidomastoid (SCM), obliquus externus
abdominis, vastus lateralis, biceps femoris (BF), tibialis anterior and peroneus longus was obtained. During whole-body maximal
rotatory voluntary isometric contraction (MRVC), only SCM and BF displayed EMG activation/inhibition patterns indicating axial
rotatory action. TMS-induced motor evoked potentials (MEPs) after caloric irrigation revealed that only SCM showed consistent
vestibular-mediated excitation/inhibition responses, i.e. an increase in MEP area contralateral to the irrigation and a decrease
in MEP area ipsilaterally (+12.7 and −6.3% of the MRVC, respectively). A putative head turn induced by this SCM activity pattern
would be in the same direction of the slow-phase eye movement. EMG in the 100 ms preceding TMS showed muscle tone values of
approximately 10% of MRVC. After caloric irrigation, these values increased by ca. 2% for all muscles bilaterally and hence
cannot explain the direction-specific SCM MEP changes. Thus, SCM MEPs show caloric-induced amplitude modulation indicating
that SCM is under both horizontal semicircular canal and corticospinal control. This vestibular modulation of corticospinal
SCM control likely occurs at cortical levels. The direction of the MEP modulation indicates a directional coupling between
vestibularly induced head and eye movements. 相似文献
92.
Natalia Doubina Michelina Stoddard Hugo A. Bronstein Alex K.‐Y. Jen Christine K. Luscombe 《Macromolecular chemistry and physics.》2009,210(22):1966-1972
The effects of binding ligand variation on the externally initiated Ni catalyzed polymerization of P3HT were investigated using a novel methodology allowing facile screening of ligands. P3HT was synthesized with >80% initiator incorporation for both mono‐ and bidentate phosphine ligands. Variation of the initiating aryl group demonstrated vastly superior results for o‐tolyl over p‐tolyl substituents.
93.
We investigate the role of vestibular information in judging the gravity-referenced eye level (i.e., earth-referenced horizon or GREL) during sagittal body tilt whilst seated. Ten bilateral labyrinthine-defective subjects (LDS) and 10 age-matched controls set a luminous dot to their perception of GREL in darkness, with and without arm pointing. Although judgements were linearly influenced by the magnitude of whole-body tilt, results showed no significant difference between LDS and age-matched controls in the subjective GREL accuracy or in the intra-subject variability of judgement. However, LDS performance without arm pointing was related to the degree of vestibular compensation inferred from another postural study performed with the same patients. LDS did not utilize upper limb input during arm pointing movements as a source of graviceptive information to compensate for the vestibular loss. The data suggest that vestibular cues are not of prime importance in GREL estimates in static conditions. The absence of difference between controls and LDS GREL performance, and the correlation between the postural task and GREL accuracy, indicate that somatosensory input may convey as much graviceptive information required for GREL judgements as the vestibular system. 相似文献
94.
95.
Gaze displacement and inter-segmental coordination during large whole body voluntary rotations 总被引:1,自引:1,他引:0
Dimitri Anastasopoulos Nausica Ziavra Mark Hollands Adolfo Bronstein 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2009,193(3):323-336
Displacements of the visual axis and multi-segmental (eye-to-foot) coordination in the yaw plane were studied in ten human
subjects (Ss) during voluntary reorientations to illuminated targets of eccentricities up to 180°. We also investigated how
knowledge of target location modifies the movement pattern. Eccentric targets (outbound trials) elicited eye, head, trunk
and foot movements at latencies ca. 0.5, 0.6, 0.7 and 1.1 s, respectively. Knowledge of target location (return trials) reduced
latencies for foot and trunk (but not eye and head) thus eye, head and trunk moved more en bloc. In most trials, the initial
gaze shift fell short of the target and more than 50% of the visual angle was covered by the sum of vestibular nystagmic fast
phases and head-in-space displacement, until target fixation. This indicates that during large gaze shifts the ‘anticompensatory’
role of the vestibulo-ocular reflex in target acquisition is prominent. During some predictable trials Ss acquired targets
with a single large gaze shift, shortening target acquisition time by more than 200 ms. In these, gaze velocity (trunk-in-space + head-on-trunk + eye-in-orbit)
remained often fairly constant for durations of up to 500 ms, suggesting that gaze velocity is a controlled parameter. Such
pattern occurred during trunk mobilization, thus eye velocity co-varied with head-in-space rather than head-on-trunk velocity.
Foot rotations were stereotyped and of constant frequency, suggesting they are generated by locomotor pattern generators.
However, knowledge of target location reduced foot latencies indicating that local and supraspinal mechanisms interact for
foot control. We propose that a single controller is responsible for the coupling of the multiple body segments and gaze velocity
control during gaze shifts. 相似文献
96.
Patients complaining of symptoms of acute vertigo present a diagnostic challenge for the clinician; the main differential diagnoses are acute unilateral peripheral vestibulopathy ("vestibular neuritis"), cerebellar stroke or migraine. The head impulse test is useful in the acute situation because, of these three diagnostic alternatives, it will only be positive in patients with vestibular neuritis. A history of acute vertigo and hearing loss suggests Ménière's disease but the clinician must be wary of anterior inferior cerebellar artery strokes which may cause audiovestibular loss due to peripheral vestibulocochleal ischaemia, although the accompanying brainstem signs should remove diagnostic ambiguity. We also discuss other less common vertigo diagnoses that may be referred to the neurologist from the acute general hospital take. As ever in neurology, a careful history and focussed examination is necessary in the evaluation and management of acute vertigo. 相似文献
97.
98.
Qingxue Wang Judy FC Chow William SB Yeung Estella YL Lau Vivian CY Lee Ernest HY Ng Pak-Chung Ho 《Journal of assisted reproduction and genetics》2014,31(12):1719-1726
Purpose
To perform Preimplantation Genetic Diagnosis (PGD) on a paternal Brca2 unknown mutation carrier with early-onset breast cancer, whose paternal grandmother and mother had breast cancer at 60s.Method
Elucidating the linkage via single sperm haplotyping on patient''s carrier brother, and identifying the genomic deletion via BLAST followed by PCR screening. PGD was subsequently conducted.Result
The mutant allele was found by using 4 microsatellite and 2 intragenic SNP markers. Recombination was detected in 8 % of sperms. BLAST was utilized to locate putative hairpin structure(s), followed by PCR screening with seven sets of primers. A novel 2,596 bp deletion containing exon 15 ~ 16 was identified. Due to the severity of phenotype and the integrity of exon 11 encoding RAD51 binding domain, and the fact that the patient''s mother also had breast cancer at her 60s, we speculate a possible coexistence of maternal breast cancer risk allele(s). Embryo biopsy was performed on day 3. Unaffected morula and blastocyst were replaced on day 5, resulting in a singleton livebirth. A breast lump appeared in the patient after delivery without the presence of malignant cells.Conclusion
Concerning the assisted reproductive option for breast cancer patients, the possibility of coexistence of multiple familial risk alleles and the significance of each mutation to the phenotype should be evaluated. To eliminate misdiagnosis resulting from recombination and/or allelic drop-out, both direct mutation detection and linkage analysis approaches may be necessary. BLAST is a very useful and cost-effective tool for identifying large genomic deletion. 相似文献99.
100.
A S Blaustein G Schmitt M C Foster R V Hayes S Bronstein 《American heart journal》1986,111(2):340-346
To separate the effects of hemodialysis on loading conditions from those on contractile state, six patients with concentric left ventricular hypertrophy and normal left ventricular function were studied before, during, and after hemodialysis. Two-dimensional-directed M-mode ultrasound was used to measure left ventricular dimensions and wall thickness; a sphygmomanometer and carotid pulse recording were used to determine peak and end-systolic blood pressure. From these data, meridional stress at end systole was calculated and stress-dimension and stress-shortening relations were derived; measurements of metabolic parameters were made simultaneously. Heart rate and systolic blood pressure were stable throughout dialysis. Reductions in left ventricular dimensions and increased shortening were evident by 30 minutes of dialysis and were largely complete by mid-dialysis. These changes coincided with a decrease in potassium and an increase in ionized calcium but not in pH, which changed only in the latter half of dialysis. When stress-dimension and stress-shortening relations were examined, both individual and group data for all coordinates before, during, and after dialysis demonstrated an excellent linear fit consistent with a single contractile state. We conclude that in stable patients with left ventricular hypertrophy, the reduction in heart size and improvement in shortening are due primarily to reductions in preload and afterload. 相似文献