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2.
Haematologica ; 2023 Dec 07.
Article in English | MEDLINE | ID: mdl-38058170

ABSTRACT

Patients with severe aplastic anemia (SAA) are at high risk for morbidity and mortality due to severe infections. We aimed to characterize the role of granulocyte transfusion (GT) in SAA. Primary outcomes were survival from first GT, including overall survival (OS) at last follow up, survival to discharge, and receipt of HSCT. Secondary outcomes included evaluation of clinical response at 7 and 30 days after GT initiation based on a clinical scoring system incorporating microbiological and radiographic response. Twenty-eight SAA patients underwent 30 GT courses with a per-dose median of 1.28 x 109 granulocyte cells/kilogram (range 0.45-4.52 x 109). OS from initial GT to median last follow up (551 days) was 50%, with 39% (11/28) alive at last follow up. Sixty-four percent (18/28) of all patients survived to hospital discharge. Patients with complete, partial, or stable response at 30 days had significantly improved OS compared to non-responders (p=0.0004). Eighty-six percent (18/21) of patients awaiting HSCT during GT underwent transplant and 62% (13/21) survived to post-HSCT discharge. Sex, type of infection, or percentage of days with absolute neutrophil count > 0.2x109/L during GT course were not predictive of survival (p=0.52, p=0.7, p=0.28). Nine of 28 (32%) patients developed new or increased human leukocyte antigen (HLA) alloimmunization during their GT course. GTs in SAA may impact survival in those with improvement or stabilization of their underlying infection. Alloimmunization can occur and OS in this population remains poor, but GTs may be a useful tool to bridge patients to curative treatment with HSCT.

3.
J Pediatr ; 262: 113624, 2023 11.
Article in English | MEDLINE | ID: mdl-37473994

ABSTRACT

OBJECTIVE: To evaluate the clinical impact of an institutional thromboprophylaxis protocol in patients with multisystem inflammatory syndrome in children (MIS-C), who are at increased risk for thromboembolism (TE). STUDY DESIGN: We conducted a single-center retrospective cohort study of children less than 18 years between March 2020 and December 2021. Eligible patients were confirmed with MIS-C and were managed with a standardized multidisciplinary treatment approach that included a thromboprophylaxis protocol to guide and unify clinical practice. For high-risk patients, prophylactic dose enoxaparin (target anti-Factor Xa 0.1-0.3 U/mL) was added. In high-risk patients with TE risk factors persistent at hospital discharge, thromboprophylaxis was prescribed for an additional 30 days. RESULTS: Of 135 patients with MIS-C, 124 (92%) required intensive care unit stay and 64 (47%) required a central venous catheter for a median duration of 5 days (IQR, 4-7). Prophylactic dose enoxaparin was initiated in 116 out of 121 patients (96%) deemed high-risk per our protocol at a median of 1 day after admission [IQR, 0-3] achieving target levels at a median of 1 day [IQR, 1-2]. The median initial anti-Factor Xa level was 0.13 u/mL [IQR, 0.05-0.19]. One patient (0.7%) developed symptomatic noncatheter related superficial vein thrombosis requiring therapeutic anticoagulation. Thromboprophylaxis was extended for 30 days after discharge in 108 out of 135 patients (80%). Bleeding events occurred in 5 patients during hospitalization (4.2%). All bleeding events were clinically relevant nonmajor bleeding. There were no deaths. CONCLUSIONS: Implementation of an institutional standardized thromboprophylaxis protocol in MIS-C was feasible and led to timely initiation of prophylactic anticoagulation and low rates of TEs and bleeding complications.


Subject(s)
Enoxaparin , Venous Thromboembolism , Child , Humans , Enoxaparin/therapeutic use , Anticoagulants/therapeutic use , Retrospective Studies , Venous Thromboembolism/drug therapy , Venous Thromboembolism/etiology , Venous Thromboembolism/prevention & control , Hemorrhage/chemically induced , Hemorrhage/complications
4.
Curr Hematol Malig Rep ; 18(4): 89-97, 2023 08.
Article in English | MEDLINE | ID: mdl-37247092

ABSTRACT

PURPOSE OF REVIEW: GATA2 deficiency is a haploinsufficiency syndrome associated with a wide spectrum of disease, including severe monocytopenia and B and NK lymphopenia, predisposition to myeloid malignancies, human papillomavirus infections, and infections with opportunistic organisms, particularly nontuberculous mycobacteria, herpes virus, and certain fungi. GATA2 mutations have variable penetrance and expressivity with imperfect genotype-phenotype correlations. However, approximately 75% of patients will develop a myeloid neoplasm at some point. Allogeneic hematopoietic cell transplantation (HCT) is the only currently available curative therapy. Here, we review the clinical manifestations of GATA2 deficiency, characterization of the hematologic abnormalities and progression to myeloid malignancy, and current HCT practices and outcomes. RECENT FINDINGS: Cytogenetic abnormalities are common with high rates of trisomy 8, monosomy 7, and unbalanced translocation der(1;7) and may suggest an underlying GATA2 deficiency in patients presenting with myelodysplastic syndrome (MDS). Mutations in ASXL1 and STAG2 are the most frequently encountered somatic mutations and are associated with lower survival probability. A recent report of 59 patients with GATA2 deficiency who underwent allogenic HCT with myeloablative, busulfan-based conditioning and post-transplant cyclophosphamide reported excellent overall and event-free survival of 85% and 82% with reversal of disease phenotype and low rates of graft versus host disease. Allogeneic HCT with myeloablative conditioning results in disease correction and should be considered for patients with a history of recurrent, disfiguring and/or severe infections, organ dysfunction, MDS with cytogenetic abnormalities, high-risk somatic mutations or transfusion dependence, or myeloid progression. Improved genotype/phenotype correlations are needed to allow for greater predictive capabilities.


Subject(s)
GATA2 Deficiency , Myelodysplastic Syndromes , Myeloproliferative Disorders , Neoplasms , Humans , Chromosome Aberrations , Disease Susceptibility , GATA2 Deficiency/diagnosis , GATA2 Deficiency/genetics , GATA2 Deficiency/therapy , GATA2 Transcription Factor/genetics , Genotype , Myelodysplastic Syndromes/genetics , Myelodysplastic Syndromes/therapy , Myelodysplastic Syndromes/pathology
5.
Transl Pediatr ; 12(2): 110-112, 2023 Feb 28.
Article in English | MEDLINE | ID: mdl-36891360
6.
J Clin Lipidol ; 17(1): 124-130, 2023.
Article in English | MEDLINE | ID: mdl-36464598

ABSTRACT

BACKGROUND: Small studies have suggested that moderate alcohol consumption increases HDL cholesterol (HDL-C) levels and cholesterol efflux capacity (CEC), a main anti-atherosclerotic HDL function. OBJECTIVES: This study aimed to understand the degree to which alcohol intake is associated with various HDL markers in a large, multiethnic population cohort, the Dallas Heart Study (DHS), and whether alcohol modifies the link between HDL markers and atherosclerotic cardiovascular disease (ASCVD). METHODS: Participants of the DHS were included if they had self-reported alcohol intake and CEC measurements (N=2,919). Alcohol intake was analyzed continuously (grams/week) and as an ordered categorical variable (never, past, light, moderate, heavy, and binge drinkers). HDL-C, CEC, HDL particle number (HDL-P), HDL particle size (HDL-size), and ApoA-I were the primary HDL measures. RESULTS: After adjustment for confounding variables, increasing continuous measure of alcohol intake was associated with increased levels of all HDL markers. Moreover, as compared to moderate drinkers, light drinkers had decreased levels of the HDL markers. CONCLUSION: In a large, multiethnic cohort, increased alcohol intake was associated with increased levels of multiple markers of HDL metabolism. However, the association of HDL markers with ASCVD risk as modified by alcohol consumption is unable to be determined in this low-risk cohort.


Subject(s)
Alcohol Drinking , Atherosclerosis , Humans , Alcohol Drinking/epidemiology , Cholesterol, HDL , Biomarkers , Ethanol
7.
Br J Haematol ; 199(5): 679-687, 2022 12.
Article in English | MEDLINE | ID: mdl-36128909

ABSTRACT

Patients with severe aplastic anaemia (SAA) are often not vaccinated against viruses due to concerns of ineffective protective antibody response and potential for pathogenic global immune system activation, leading to relapse. We evaluated the impact of COVID-19 vaccination on haematological indices and disease status and characterized the humoural and cellular responses to vaccination in 50 SAA patients, who were previously treated with immunosuppressive therapy (IST). There was no significant difference in haemoglobin (p = 0.52), platelet count (p = 0.67), absolute lymphocyte (p = 0.42) and neutrophil (p = 0.98) counts prior to and after completion of vaccination series. Relapse after vaccination, defined as a progressive decline in counts requiring treatment, occurred in three patients (6%). Humoural response was detectable in 90% (28/31) of cases by reduction in an in-vitro Angiotensin II Converting Enzyme (ACE2) binding and neutralization assay, even in patients receiving ciclosporin (10/11, 90.1%). Comparison of spike-specific T-cell responses in 27 SAA patients and 10 control subjects revealed qualitatively similar CD4+ Th1-dominant responses to vaccination. There was no difference in CD4+ (p = 0.77) or CD8+ (p = 0.74) T-cell responses between patients on or off ciclosporin therapy at the time of vaccination. Our data highlight appropriate humoural and cellular responses in SAA previously treated with IST and true relapse after vaccination is rare.


Subject(s)
Anemia, Aplastic , COVID-19 , Humans , Anemia, Aplastic/drug therapy , Cyclosporine/therapeutic use , COVID-19 Vaccines/therapeutic use , SARS-CoV-2 , Immunosuppressive Agents/therapeutic use , COVID-19/prevention & control , Recurrence , Immunity , Vaccination
8.
Nat Biomed Eng ; 4(6): 636-648, 2020 06.
Article in English | MEDLINE | ID: mdl-32483299

ABSTRACT

The formulations of peptide-based antitumour vaccines being tested in clinical studies are generally associated with weak potency. Here, we show that pharmacokinetically tuning the responses of peptide vaccines by fusing the peptide epitopes to carrier proteins optimizes vaccine immunogenicity in mice. In particular, we show in immunized mice that the carrier protein transthyretin simultaneously optimizes three factors: efficient antigen uptake in draining lymphatics from the site of injection, protection of antigen payloads from proteolytic degradation and reduction of antigen presentation in uninflamed distal lymphoid organs. Optimizing these factors increases vaccine immunogenicity by up to 90-fold and maximizes the responses to viral antigens, tumour-associated antigens, oncofetal antigens and shared neoantigens. Protein-peptide epitope fusions represent a facile and generalizable strategy for enhancing the T-cell responses elicited by subunit vaccines.


Subject(s)
Cancer Vaccines/immunology , Cancer Vaccines/pharmacology , Immunogenicity, Vaccine/immunology , T-Lymphocytes/immunology , Vaccines, Subunit/immunology , Vaccines, Subunit/pharmacokinetics , Albumins/immunology , Animals , Antigens, Neoplasm , Basic-Leucine Zipper Transcription Factors , CD8-Positive T-Lymphocytes , Cell Line, Tumor , Epitopes , Immunity, Cellular , Immunotherapy , Mice , Mice, Inbred C57BL , Mice, Knockout , Repressor Proteins/genetics
9.
Cell ; 164(4): 617-31, 2016 Feb 11.
Article in English | MEDLINE | ID: mdl-26871628

ABSTRACT

The motivation to seek social contact may arise from either positive or negative emotional states, as social interaction can be rewarding and social isolation can be aversive. While ventral tegmental area (VTA) dopamine (DA) neurons may mediate social reward, a cellular substrate for the negative affective state of loneliness has remained elusive. Here, we identify a functional role for DA neurons in the dorsal raphe nucleus (DRN), in which we observe synaptic changes following acute social isolation. DRN DA neurons show increased activity upon social contact following isolation, revealed by in vivo calcium imaging. Optogenetic activation of DRN DA neurons increases social preference but causes place avoidance. Furthermore, these neurons are necessary for promoting rebound sociability following an acute period of isolation. Finally, the degree to which these neurons modulate behavior is predicted by social rank, together supporting a role for DRN dopamine neurons in mediating a loneliness-like state. PAPERCLIP.


Subject(s)
Dopaminergic Neurons/pathology , Dorsal Raphe Nucleus/pathology , Loneliness , Animals , Dopamine/metabolism , Dorsal Raphe Nucleus/physiopathology , Glutamic Acid/metabolism , In Vitro Techniques , Male , Mice , Optogenetics , Patch-Clamp Techniques , Reward , Synapses , Ventral Tegmental Area/physiology
10.
J Child Neurol ; 26(3): 373-6, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21257840

ABSTRACT

A 3-year-old boy who had been a 23-week premature infant had subacute onset of abnormal gait, which progressed to generalized weakness with severe weakness of neck extensors. He had U waves on electrocardiography. His serum potassium was 1.8 mmol/L. The patient had a gastrostomy tube due to chronic feeding issues and was treated with inhaled albuterol for chronic lung disease. When his oral intake regressed, his family administered one of his oral supplements through the gastrostomy tube; the supplement was low in potassium. This feeding regression continued for several months. He had no additional gastrointestinal or renal loss of potassium. He had frequent exacerbations of his bronchopulmonary dysplasia. His history suggested he had chronic potassium depletion and that albuterol may have led to further potassium redistribution, exacerbating his hypokalemia. As more extremely premature infants survive with chronic feeding and respiratory issues, this presentation may become more common.


Subject(s)
Head/physiopathology , Infant, Premature , Movement Disorders/pathology , Movement Disorders/physiopathology , Child, Preschool , Disease Progression , Humans , Infant, Newborn
11.
Pap. psicol ; 32(1): 48-58, ene. 2011. ilus
Article in Spanish | IBECS | ID: ibc-97321

ABSTRACT

En este trabajo se propone una nueva conceptualización del clima de los equipos de trabajo, según la cual el clima es el patrón que componen las percepciones del equipo que tienen sus miembros. Esta conceptualización considera el clima como una propiedad configuracional de los equipos, donde las dimensiones de la dispersión tienen un papel importante. Se revisan los trabajos empíricos realizados acerca de los antecedentes y consecuencias de la dispersión intra-unidad en las percepciones de clima. Finalmente, se analizan las implicaciones prácticas de la conceptualización propuesta, y de los resultados de la investigación (AU)


We propose a new conceptualization of work team climate. According to it, work team climate refers to the pattern of employees’ perceptions of their team. From this conceptualization, team climate is a configurational property, where dispersion dimensions have an important role to play. We review empirical research on the antecedents and consequences of within-team dispersion in climate perceptions. Finally, we draw a number of practical implications stemming from the proposed conceptualization and the reviewed research outcomes (AU)


Subject(s)
Humans , Group Processes , 16360 , Organizational Culture , Models, Organizational , 16359/policies , Operations Research
12.
Neurophysiol Clin ; 39(2): 85-93, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19467438

ABSTRACT

AIMS: To monitor acute brain injury in the neurological intensive care unit (NICU), we used EEG and somatosensory evoked potentials (SEP) in combination to achieve more accuracy in detecting brain function deterioration. METHODS: Sixty-eight patients (head trauma and intracranial hemorrhage; GCS<9) were monitored with continuous EEG-SEP and intracranial pressure monitoring (ICP). RESULTS: Fifty-five patients were considered "stable" or improving, considering the GCS and CT scan: in this group, SEP didn't show significant changes. Thirteen patients showed neurological deteriorations and, in all patients, cortical SEP showed significant alterations (amplitude decrease>50% often till complete disappearance). SEP deterioration anticipated ICP increase in 30%, was contemporary in 38%, and followed ICP increase in 23%. Considering SEP and ICP in relation to clinical course, all patients but one with ICP less than 20 mmHg were stable, while the three patients with ICP greater than 40 mmHg all died. Among the 26 patients with ICP of 20-40 mmHg, 17 were stable, while nine showed clinical and neurophysiological deterioration. Thus, there is a range of ICP values (20-40 mmHg) were ICP is scarcely indicative of clinical deterioration, rather it is the SEP changes that identify brain function deterioration. Therefore, SEP have a twofold interest with respect to ICP: their changes can precede an ICP increase and they can constitute a complementary tool to interpret ICP trends. It has been very important to associate SEP and EEG: about 60% of our patients were deeply sedated and, because of their relative insensitivity to anesthetics, only SEP allowed us to monitor brain damage evolution when EEG was scarcely valuable. CONCLUSIONS: We observed 3% of nonconvulsive status epilepticus compared to 18% of neurological deterioration. If the aim of neurophysiological monitoring is to "detect and protect", it may not be limited to detecting seizures, rather it should be able to identify brain deterioration, so we propose the combined monitoring of EEG with SEP.


Subject(s)
Brain Injuries/physiopathology , Electroencephalography/methods , Evoked Potentials, Somatosensory , Monitoring, Physiologic/methods , Adolescent , Adult , Aged , Brain Injuries/etiology , Brain Ischemia/complications , Brain Ischemia/physiopathology , Disease Progression , Female , Glasgow Coma Scale , Humans , Intracranial Hemorrhage, Traumatic/physiopathology , Intracranial Hypertension/diagnosis , Intracranial Hypertension/etiology , Intracranial Hypertension/mortality , Intracranial Hypertension/physiopathology , Male , Middle Aged , Status Epilepticus/physiopathology , Subarachnoid Hemorrhage/etiology , Subarachnoid Hemorrhage/physiopathology , Young Adult
13.
Hippokratia ; 11(1): 30-4, 2007 Jan.
Article in English | MEDLINE | ID: mdl-19582174

ABSTRACT

BACKGROUND: Intravenous iron and erythropoietin are commonly used for the treatment of anemia in end stage renal disease (ESRD) patients. Even though i.v. iron is proven to be very effective, there is great concern regarding its possible toxic effects. The aim of our study was to evaluate the possible correlation between iron administration and the incidence of angina pectoris in hemodialysis patients. METHODS: The study sample consisted of 10 stable coronary heart disease patients, receiving chronic hemodialysis treatment. The patients followed consecutively three different i.v. iron dose regimens according to their needs. Their standard monthly laboratory measurements were correlated with the incidence of angina pectoris and i.v. iron treatment. RESULTS: Hematocrit, ferritin, serum iron and mean rhEPO dose were related to the total amount of administered iron. Angina pectoris was related to intensive iron treatment, age and platelet count. Total white blood cell count were related to hemodialysis duration, platelet count and serum triglycerides. CONCLUSION: It is suggested that the intensive intravenous iron treatment (300 mg/week) is associated with the increased incidence of angina pectoris in stable coronary heart disease patients receiving hemodialysis.

15.
Magn Reson Imaging ; 21(10): 1175-89, 2003 Dec.
Article in English | MEDLINE | ID: mdl-14725925

ABSTRACT

The purpose of this study was the development of a real-time filtering procedure of MRI artifacts in order to monitor the EEG activity during continuous EEG/fMRI acquisition. The development of a combined EEG and fMRI technique has increased in the past few years. Preliminary "spike-triggered" applications have been possible because in this method, EEG knowledge was only necessary to identify a trigger signal to start a delayed fMRI acquisition. In this way, the two methods were used together but in an interleaved manner. In real simultaneous applications, like event-related fMRI study, artifacts induced by MRI events on EEG traces represent a substantial obstacle for a right analysis. Up until now, the methods proposed to solve this problem are mainly based on procedures to remove post-processing artifacts without the possibility to control electrophysiological behavior of the patient during fMRI scan. Moreover, these methods are not characterized by a strong "prior knowledge" of the artifact, which is an imperative condition to avoid any loss of information on the physiological signals recovered after filtering. In this work, we present a new method to perform simultaneous EEG/fMRI study with real-time artifacts filtering characterized by a procedure based on a preliminary analytical study of EPI sequence parameters-related EEG-artifact shapes. Standard EEG equipment was modified in order to work properly during ultra-fast MRI acquisitions. Changes included: high-performance acquisition device; electrodes/cap/wires/cables materials and geometric design; shielding box for EEG signal receiver; optical fiber link; and software. The effects of the RF pulse and time-varying magnetic fields were minimized by using a correct head cap wires-locked environment montage and then removed during EEG/fMRI acquisition with a subtraction algorithm that takes in account the most significant EPI sequence parameters. The on-line method also allows a further post-processing utilization.


Subject(s)
Artifacts , Electroencephalography , Magnetic Resonance Imaging , Signal Processing, Computer-Assisted , Algorithms , Echo-Planar Imaging/methods , Electroencephalography/methods , Humans , Magnetic Resonance Imaging/methods
16.
Psychol Health ; 16(5): 511-25, 2001 Sep.
Article in English | MEDLINE | ID: mdl-22804496

ABSTRACT

Abstract The main objective of this study is to test the effects over time of three role stress variables (role conflict, role ambiguity and role overload) on the three burnout dimensions (emotional exhaustion, depersonalization and personal accomplishment). Based on theoretical models on burnout and on meta-analytical research, it is hypothesized that the three role stress variables will predict changes over time in emotional exhaustion and depersonalization, but not in personal accomplishment. The results obtained by means of hierarchical regression analysis partially support the hypothesis. The three role stress variables predict emotional exhaustion over time. Role conflict and role overload predict depersonalization over time. Finally, contrary to expectations, role ambiguity predicts personal accomplishment over time.

17.
Ital J Neurol Sci ; 11(2): 113-30, 1990 Apr.
Article in English | MEDLINE | ID: mdl-2361850

ABSTRACT

The so-called contingent negative variation (CNV) is a slow brain potential representing a complex of variously overlapped "endogenous" components of behavior related to different reasonably well-known neurocognitive processes. CNV complex evoked with a standard paradigm (S1-2 sec-S2-motor response) and reaction time (RT) to imperative signal (S2) were recorded and measured in 11 patients with initial presenile idiopathic cognitive decline (PICD), 8 with presenile Alzheimer-type dementia (PAD) and 10 healthy age-matched controls. Significant group differences were obtained for measures of some CNV components, particularly of the late pre-S2 CNV. No significant CNV activity, very prolonged RTs and sometimes characteristic post-imperative negative variation (PINV) were observed in the majority of patients with PAD. These results suggest that CNV complex and RT changes similar to those observed in our patients may constitute a valuable clue for the study of pathophysiological brain functioning in the early stages of presenile idiopathic mental deterioration.


Subject(s)
Alzheimer Disease/physiopathology , Cognition Disorders/physiopathology , Electroencephalography , Reaction Time/physiology , Aged , Alzheimer Disease/psychology , Cognition Disorders/psychology , Female , Humans , Male , Middle Aged , Neuropsychological Tests
18.
Ital J Neurol Sci ; 9(3): 219-30, 1988 Jun.
Article in English | MEDLINE | ID: mdl-3403214

ABSTRACT

20 selected right-handed very healthy subjects (10 young adults and 10 presenile subjects mean age 28.3 and 59.6) were tested for CNV activity with a simple warned reaction time (RT) paradigm. EEG and CNV components (post-S1, N1, P2, P3; early CNV; N1200; late CNV; CNV resolution) were recorded from Fz, C3, Cz, C4, P3, Pz, and P4 referenced to linked mastoid electrodes. EOG, RT and stimuli were also recorded. The presenile group differed significantly from the younger group in the auditory post-S1 N1 and P3, and in the early (O-wave) and late (P-wave) CNV complex components. A progressive amplitude reduction only in frontal leads between O-wave and P-wave with the lowest point being reached in the P-wave was characteristic in the presenile group. Further, presenile subjects showed relatively flat CNV waveshapes of low amplitude and, as a whole, performed a little less well than young persons. This finding suggests that the statistically significant changes in post-S1 EPRs and CNV activity recorded in our presenile subjects, without appreciable deficits in behavioral and mental performance, could be alerting signs of early brain involutional processes related to minimal and subclinical decrement of orienting, attentiveness and response preparation capabilities. If such is the case and it could be confirmed in a larger sample of very healthy subjects, these age-related changes in the presenium could be of considerable practical importance for clinical and research applications.


Subject(s)
Aging/physiology , Cognition/physiology , Adult , Electroencephalography , Evoked Potentials , Female , Humans , Male , Middle Aged
19.
Electroencephalogr Clin Neurophysiol ; 61(4): 272-86, 1985 Oct.
Article in English | MEDLINE | ID: mdl-2411506

ABSTRACT

In 23 healthy adult volunteers motor action potentials (MAPs) were elicited in upper and lower limb muscles during stimulation of appropriate sites at spinal and scalp level, through skin electrodes. 'Bifocal' stimulation of scalp and spine motor tracts was performed with 2 plaques (3.5 cm2 each), delivering single pulses of 440-940 mA, less than 50 microseconds in duration, which elicited high voltage (up to 10 mV) MAPs in arm and leg muscles. 'Unifocal' stimulation of scalp was carried out through a cathode consisting in a belt or in a series of rectangular interconnected plaques secured around the head, 1-2 cm rostral to the nasion-inion plane, and in a circular anode placed on the appropriate scalp site. MAPs with similar amplitude-latency characteristics were recorded with both 'bifocal' and 'unifocal' stimulating methods. However, the 'unifocal' stimulation necessitated 5-10 times less current than the 'bifocal' one. The 'unifocal' device using the interconnected plaques (6-12 in number) provided the most tolerable stimuli with the lowest amount of current (60-106 mA, rectangular pulses of 100-150 microseconds). Conduction times and velocities of motor pathways in various 'central' and 'peripheral' districts were calculated. Voluntary contraction of target muscles remarkably enhanced MAP amplitudes during scalp, but not during spine stimulation. A nerve action potential was recorded from ulnar nerve during scalp stimulation. MAPs in hand muscles to scalp stimulation were obliterated by the simultaneous activation of the peripheral fibres innervating the target muscle, because of collision between ortho- and antidromically propagated motor impulses. Anodal stimuli showed liminal values significantly lower than the cathodal ones. Mapping studies have been carried out with 'unifocal' scalp stimulation by using different types of anode and of stimulus parameters.


Subject(s)
Brain/physiology , Motor Activity/physiology , Muscles/innervation , Spinal Cord/physiology , Action Potentials , Adult , Arm , Electric Stimulation , Electromyography , Female , Humans , Leg , Male , Movement , Muscles/physiology
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