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Biomedical subjects

C Toro

Publications and source records attributed to C Toro.

At least 19 recordsLinked to original sources
PubMed2001

Somatosensory evoked potentials as a marker of disease burden in type 3 Gaucher disease.

The authors compared stretch-evoked somatosensory evoked potentials (SEP) of 18 type 3 Gaucher disease (GD3) patients (two with progressive myoclonus epilepsy [PME]) with 22 age-matched normal controls and six patients with type 1 (nonneuronopathic) Gaucher disease (GD1). The mean P1-N2 SEP amplitude in GD3 patients was significantly larger than the SEP in controls and in GD1 patients, and there was a significant negative correlation between SEP amplitude and the IQ of GD3 patients. The authors conclude that abnormal cortical inhibition is a unifying feature of GD3 patients and correlates with the degree of cognitive deficit.

Adolescent↗
PubMed2001

Event-related desynchronization in reaction time paradigms: a comparison with event-related potentials and corticospinal excitability.

OBJECTIVES: To study cortical activity in different motor tasks, we compared event-related desynchronization (ERD) and event-related potentials (ERPs) in different reaction time (RT) paradigms with the time course of corticospinal excitability. METHODS: Nine right-handed, normal subjects performed right or left thumb extensions in simple, choice and go/no go auditory RT paradigms. Eight subjects had participated in a previous study evaluating changes in corticospinal excitability during the same paradigms. Twenty-nine EEG channels with electrooculogram and bilateral EMG monitoring were collected. ERPs and ERD of 10 and 18-22 Hz bands were obtained with respect to tone administration and EMG onset. RESULTS: Trials with movement showed lateralized ERP components, corresponding to the motor potential (MP), both in the averages on the tone and on EMG. The MP corresponded well in time and location to the rise in corticospinal excitability on the moving side observed in the previous study. Sensorimotor ERD, followed by event-related synchronization (ERS), was present for trials with movements and for the no go. ERD was present contralaterally during movement preparation and in no go trials, while it was bilateral during motor execution. No go ERD was followed more rapidly by ERS than in trials with movement. This finding suggests that in no go trials, there is a brief active process in the sensorimotor areas. ERD and ERS do not correspond, respectively, in time and location to increases and decreases in corticospinal excitability. In fact, ERD is bilateral during movement execution, when corticospinal inhibition of the side at rest is observed. Contralateral no go ERS occurs later than corticospinal inhibition, which is bilateral. CONCLUSIONS: These findings may suggest that ERD is compatible with both corticospinal activation and inhibition, ERS indicating the removal of either, resulting in cortical idling.

Acoustic Stimulation↗
PubMed2001

[Acute myocardial infarction caused by total occlusion of the left main coronary artery treated with percutaneous endoluminal revascularization. Clinical case].

We report a 43 years old female who developed an intense precordial pain and arterial hypotension. The patient was admitted to the emergency room in cardiogenic shock. An emergency angiography revealed a total occlusion of the left main coronary artery. An endoluminal coronary angioplasty with the placement of two stents was performed and coronary reperfusion TIMI III was achieved. The patient had a good evolution and one month later, a surgical revascularization was done, to avoid new occlusions. She was discharged in good conditions and in functional capacity I.

Adult↗
PubMed2001

[Prevalence of primary Helicobacter pylori resistance to eight antimicrobial agents in a hospital in Madrid].

The aim of this study was to determine the prevalence of primary Helicobacter pylori resistance, and to investigate the relationship with factors such as age and sex. During 1998, 106 H. pylori strains collected from dyspeptic patients who had had no previous H. pylori treatment were studied. The minimun inhibitory concentrations of metronidazole, amoxicillin, clarithromycin, tetracycline, azithromycin, clindamycin, cefotaxime and ciprofloxacin were determined by E-test.((R)). The overall prevalence of primary metronidazole resistance was 40.6%. Although it was more frequent in women than in men (44.4% vs. 37.7%), the difference was significant only in the women who were under 45 years of age. For the rest of the antibiotics, the primary resistance rates were the following: clarithromycin 9.5%, azithromycin 10.3%, clindamycin 13.1%, and ciprofloxacin 7.9%. No resistance to tetracycline and b-lactam antibiotics was found. Clarithromycin and amoxicillin were the most active compounds of the macrolides and b-lactams studied, respectively.

Adult↗
PubMed2000

Co-stimulatory signals increase the reactivity of gammadelta T cells towards mycobacterial antigens.

Although it has been shown that gammadelta T lymphocytes are able to react with different cell-associated or soluble antigens, the immune repertoire of these cells appears to be skewed to the recognition of mycobacterial antigens. We have studied the number and reactivity of gammadelta T cells towards several mycobacterial antigens in patients with tuberculosis and leprosy, as well as their healthy contacts and control individuals. We found an increased number of Vdelta2+ cells in healthy contacts (PPD+ and lepromin+) and tuberculoid leprosy patients. The gammadelta T cells from lepromatous leprosy showed a decreased response to all antigens tested, but some of these patients exhibited a significant response to the 30-kD glycoprotein of Mycobacterium tuberculosis. Interestingly, the reactivity of gammadelta T cells against mycobacterial antigens was significantly increased by costimulatory signals generated through CD7, LFA-1, CD50 and CD69 in all groups. However, signalling through CD69 did not enhance the responsiveness of gammadelta lymphocytes from lepromatous patients. On the other hand, the in vitro blockade of IL-10 with a specific antibody enhanced the cell proliferation of gammadelta lymphocytes from lepromatous leprosy patients, whereas exogenous IL-10 had an opposite effect in most individuals studied. These results suggest the potential role of different cell membrane receptors in the regulation of gammadelta T cell proliferation induced by mycobacteria, as well as the possible involvement of IL-10 in this phenomenon.

Antibodies, Monoclonal↗
PubMed2000

Movement-related electroencephalographic desynchronization in patients with hand cramps: evidence for motor cortical involvement in focal dystonia.

We studied the dynamic changes in the amplitude of scalp electroencephalographic (EEG) oscillations to self-paced simple index finger abduction movements in patients with writer's cramp and compared them with those of normal aged-matched controls. The changes in EEG oscillations were measured in predefined frequency bands (8-10, 10-12, 12-20, and 20-30 Hz) by using the event-related desynchronization technique. Movements of the affected and unaffected hand in patients with writer's cramp showed significantly less reduction in 20- to 30-Hz power compared with controls. The differences in movement-related EEG power decline were apparent over the contralateral central and midline regions before and after electromyographic onset. Because EEG beta rhythm in the sensorimotor region likely emanates from the motor cortex and is related to ongoing muscle activity, this abnormality could be a manifestation of the abnormal motor command at the cortical level.

Adult↗
PubMed1998

Task-related coherence and task-related spectral power changes during sequential finger movements.

In order to investigate the activity of cortical regions in the control of complex movements, we studied task-related coherence (TRCoh) and task-related spectral power (TRPow) changes in 8 right-handed subjects during the execution of 4 different finger movement sequences of increasing complexity. All sequences were performed with the right hand and were paced by a metronome at 2 Hz. EEG power spectra and coherence values were computed within alpha (8-12 Hz) and beta (13-20 Hz) frequency bands for 29 scalp EEG positions during the execution of the sequences and were compared with values obtained during a rest (control) condition. Movement sequences were associated with TRPow decreases in the alpha and beta frequency bands over bilateral sensorimotor and parietal areas, with a preponderance over the contralateral hemisphere. Increases of TRCoh occurred over bilateral frontocentral regions. TRCoh decreases were present over the temporal and occipital areas. The spatial extent and the magnitude of TRPow decreases and TRCoh increases in both frequency bands were greater for sequential movements of higher complexity than for simpler ones. These results are consistent with previous findings of bilateral activation of sensorimotor areas during sequential finger movements. Moreover, the present results indicate an active intercommunication between bilateral and mesial central and prefrontal regions which becomes more intense with more complex sequential movements.

Adult↗
PubMed1998

Physiologic studies of spinal inhibitory circuits in patients with stiff-person syndrome.

OBJECTIVE: To test inhibitory spinal circuits in patients with stiff-person syndrome (SPS). BACKGROUND: Patients with SPS have fluctuating muscle stiffness and spasms, and most have antibodies against GABAergic neurons. We predicted they would also have abnormalities of spinal GABAergic circuits. DESIGN/METHODS: Physiologic methods using H-reflexes were used to test reciprocal inhibition in the forearm and thigh, vibration-induced inhibition of flexor carpi radialis and soleus H-reflexes, recurrent inhibition, and nonreciprocal (1b) inhibition of soleus H-reflexes. RESULTS: Vibration-induced inhibition of H-reflexes was diminished in eight of nine patients tested, but the presynaptic period of reciprocal inhibition was normal in most patients. Both circuits are presumed to involve presynaptic inhibition and GABAergic interneurons. Presumed glycinergic circuits, including the first period of reciprocal inhibition and nonreciprocal (1b) inhibition, showed occasional abnormalities. Recurrent inhibition was normal in all five patients tested. CONCLUSION: Differences between the two presumptive GABAergic circuits may indicate that not all populations of GABAergic neurons are uniformly affected in SPS. The involvement of presumptive glycinergic circuits in some patients could point to impairment of nonGABAergic neurons, unrecognized involvement of GABAergic neurons in these inhibitory circuits, or, more likely, alterations of supraspinal systems that exert descending control over spinal circuits.

Adult↗
PubMed1997

Event-related desynchronization (ERD) in the alpha frequency during development of implicit and explicit learning.

To understand the role of the motor cortex in implicit and explicit learning, we studied alpha event-related desynchronization (ERD) while 13 right-handed individuals performed a variation of the serial reaction time task (SRTT). EEG signals were recorded simultaneously from 29 scalp locations and the ERD was computed. During data collection, all subjects developed implicit knowledge, demonstrated by shortening of the response time, and explicit knowledge of the test sequence. The average ERD maps of all 13 subjects demonstrated that during the initial learning, there was a decline in alpha band power that was maximal over the contralateral central region. The ERD reached a transient peak amplitude at a point when the subjects attained full explicit knowledge, and diminished subsequently. The transient peak in ERD was highly significant at C3. These electrophysiologic findings support previous studies which have demonstrated that motor activity changes as behavior changes over the course of learning.

Adult↗
PubMed1997

Event-related coherence and event-related desynchronization/synchronization in the 10 Hz and 20 Hz EEG during self-paced movements.

To investigate the activity of cortical regions in the control of movement, we studied event-related desynchronization/synchronization (ERD/ERS), event-related coherence (ERC), and phase coherence in 29-channel EEGs from 9 subjects performing self-paced movements of the right index finger. Movement preparation and execution produced ERD over the sensorimotor areas at 10 Hz and 20 Hz, followed by ERS. ERD corresponded spatiotemporally to an increase in coherence over the frontocentral areas. For both frequency bands, ERD began over the left sensorimotor areas and became bilateral at the time of movement onset. The coherence increase with frontal areas began in the left central areas and became symmetrical after EMG onset. The ERD and coherence increase was longer at 10 Hz than at 20 Hz. Phase coherence at 10 Hz showed a lead of anterior regions to posterior regions throughout the time period, and at 20 Hz showed a tendency toward zero phase delay corresponding with the movement. EEG desynchronization parallels functional coupling over sensorimotor and frontal areas. Event-related coherence and phase coherence findings implicate the frontal lobes in control of movement planning and execution. The involvement of different frequency bands with different timings may represent parallel changes in the cortical network.

Adult↗
PubMed1997

Steady-state movement-related cortical potentials: a new approach to assessing cortical activity associated with fast repetitive finger movements.

Traditionally, studies of movement-related cortical potentials have focused on the preparation of single self-paced movements performed slowly. We studied MRCPs elicited by metronome-paced, fast repetitive finger movements (2/s) with 28-channel (10 normal subjects) and 122-channel (two subjects) EEG. EMG-locked averaging of 500 ms time windows (300 ms before to 200 ms after each EMG onset) produced a distinct pattern of phasic MRCPs (steady-state MRCPs). The main components were a pre-movement peak (pre-MP), 57 ms before EMG onset, and a post-movement peak (post-MP), 93 ms after EMG onset. From timing information and topographic mapping results, we propose that the pre-MP is largely generated by a tangential source in the anterior bank of the central sulcus and reflects precentral motor processing, whereas the post-MP is generated in the posterior bank of the central sulcus and represents post-central feedback processing. Steady-state MRCPs require actual recording times of less than 10 min, and show excellent inter-session reproducibility. These characteristics may make them convenient for studying sensorimotor cortex activity experimentally and clinically.

Adult↗
PubMed1997

Self-paced versus metronome-paced finger movements. A positron emission tomography study.

To evaluate the hypothesis that self-paced movements are mediated primarily by the supplementary motor area, whereas externally triggered movements are mainly affected by the lateral premotor cortex, different movements in 6 healthy volunteers were studied while changes in regional cerebral blood flow (rCBF) were measured using positron emission tomography (PET) and 15O-labeled water. Subjects made a series of finger opposition movements initiated in a self-paced manner every 4 to 6 seconds, and separately, made continuous finger opposition movements at a frequency of 2 Hz paced by a metronome. The primary motor cortex, lateral area 6, cerebellum on both sides, and caudal cingulate motor area, and the putamen and thalamus on the contralateral side were more active during the metronome-paced movements. The increases in rCBF in these areas are likely the result of the larger number of movements per minute made with the externally triggered task. The anterior supplementary motor area and rostral cingulate motor area in the midline, prefrontal cortices bilaterally, and lobus parietalis inferior on the ipsilateral side were more active during the self-paced movements. Increases in rCBF in those areas, which include medial premotor structures, may be related to the increased time devoted to planning the movement in this condition.

Adult↗
PubMed1996

Locating the motor cortex on the MRI with transcranial magnetic stimulation and PET.

Transcranial magnetic stimulation with a focal coil was used to map the cortical representation of a hand muscle in four healthy subjects. In each subject, the three-dimensional locations of the magnetic stimulation positions and about 400 positions on the surface of the head were digitized. The amplitude-weighted center of gravity of each subject's map was found, and a line perpendicular to the local head surface was projected inward. The digitized heads were registered with the subjects' MRIs using the scalp contours. The coordinate transformations yielded by this process were used to map the stimulation positions and the perpendicular line into the MRIs. Brain areas imaged with positron emission tomography (PET) and 15O-labeled water, activated by movement of the same muscle, were registered with the MRIs using the brain contours. In all cases, the magnetic stimulation lines encountered the surface of the brain at the anterior lip of the central sulcus and ran along the precentral gyrus a few millimeters anterior to the central sulcus, coming within 5-22 mm of all the PET activation maxima. This technique demonstrates the accuracy of transcranial magnetic stimulation for locating the primary motor area.

Adult↗
PubMed1996

Adaptation motor learning of arm movements in patients with cerebellar disease.

OBJECTIVE: To design a test of motor learning using arm movements in normal subjects and patients with cerebellar disease. METHODS: Elbow angle was continuously displayed as a cursor (a dot) on a computer screen, and subjects made ballistic elbow flexion and extension movements to try to move the cursor between two targets on the screen. The relation between the arm movement and its visual feedback was changed, and the subjects reacted by adapting the amplitude of their movements in subsequent trials. RESULTS: The consecutive errors showed exponential learning curves during adaptation, which were quantified by their steepness. Ten patients with isolated cerebellar or olivopontocerebellar degeneration had less steep learning curves than normal subjects, indicating a failure of adaptation motor learning in cerebellar disease. The results show that this test may be useful for the analysis of motor learning.

Adaptation, Physiological↗
PubMed1996

Symptomatic and essential palatal tremor. 3. Abnormal motor learning.

BACKGROUND: Palatal tremor is divided into symptomatic palatal tremor (SPT) and essential palatal tremor (EPT) on the basis of clinical features. The inferior olive seems to be abnormal in SPT, but not EPT. Because the inferior olive is likely to be involved in several types of motor learning, it is hypothesised that motor learning would be abnormal in patients with SPT, but not those with EPT. METHODS: In six patients with SPT and four patients with EPT, two motor learning paradigms were studied--the classical conditioning of an acoustically elicited eyeblink with electrical supraorbital nerve shock and a test of adaptation of ballistic arm movements to a change of the gain. RESULTS: Classical conditioning was impaired unilaterally or bilaterally in the patients with SPT, depending on whether they had unilateral or bilateral abnormalities of the inferior olives, except for the two least affected patients. All but one of the patients with EPT had normal conditioning. On the adaptation test of arm movements, most of the patients with SPT had impaired learning of the arm contralateral to the hypertrophied inferior olive, regardless of whether the abnormality was unilateral or bilateral, but all patients with EPT had normal results. CONCLUSIONS: In SPT pseudohypertrophy of the inferior olive leads to defective cerebellar function, whereas in EPT the inferior olive functions normally.

Adult↗