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115 records – page 1 of 12.

Age-related susceptibility to experimental autoimmune myasthenia gravis: immunological and electrophysiological aspects.

https://arctichealth.org/en/permalink/ahliterature57596
Source
Muscle Nerve. 1997 Sep;20(9):1091-101
Publication Type
Article
Date
Sep-1997
Author
A C Hoedemaekers
J J Verschuuren
F. Spaans
Y F Graus
S. Riemersma
P J van Breda Vriesman
M H De Baets
Author Affiliation
Department of Immunology, Maastricht University, The Netherlands.
Source
Muscle Nerve. 1997 Sep;20(9):1091-101
Date
Sep-1997
Language
English
Publication Type
Article
Keywords
Aging - immunology - physiology
Animals
Antibodies - immunology
Chronic Disease
Disease Susceptibility
Electrophysiology
Female
Immunization
Myasthenia Gravis - immunology - physiopathology
Neuromuscular Junction - physiopathology
Osmolar Concentration
Rats
Rats, Inbred BN
Rats, Inbred Lew
Receptors, Cholinergic - immunology - metabolism
Research Support, Non-U.S. Gov't
Synaptic Transmission
Abstract
Susceptibility to experimental autoimmune myasthenia gravis (EAMG) was found to decrease with aging in both Lewis and Brown Norway (BN) rats. In this study, the difference in susceptibility between young and aged Lewis and BN rats was used to analyze factors determining the clinical severity of EAMG. The incidence and severity of muscular weakness did not correlate with acetylcholine receptor (AChR) loss nor with the ability of antibodies to interfere with AChR function. Aged rats showed significantly lower anti-rat AChR antibody titers than young rats and developed less severe or no clinical signs of disease. In individual young or aged rats, however, no significant correlation was found between the clinical signs of disease and anti-rat AChR titer. Neuromuscular transmission was found to change with aging as measured by single-fiber electromyography (SFEMG). In aged BN rats, increased jitter and blockings were found even before EAMG induction. Despite this disturbed neuromuscular transmission, these aged BN rats were clinically resistant against induction of EAMG. The results of this study indicate that the age-related susceptibility to EAMG is influenced by factors determined by the immune attack as well as mechanisms at the level of the neuromuscular junction.
PubMed ID
9270663 View in PubMed
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[A hyperpolarization-activated current in rat menthol-sensitive sensory neurons]

https://arctichealth.org/en/permalink/ahliterature92273
Source
Fiziol Zh. 2008;54(4):16-22
Publication Type
Article
Date
2008
Author
Kondrats'kyi A P
Kondrats'ka K O
Sotkis H V
Naid'onov V H
Shuba Ia M
Source
Fiziol Zh. 2008;54(4):16-22
Date
2008
Language
Ukrainian
Publication Type
Article
Keywords
Animals
Cells, Cultured
Cold Temperature
Cyclic Nucleotide-Gated Cation Channels - metabolism
Electrophysiology
Ganglia, Spinal - cytology - drug effects - metabolism
Menthol - pharmacology
Neurons, Afferent - drug effects - metabolism
Potassium Channels - metabolism
Rats
TRPM Cation Channels - metabolism
Abstract
In the present study we have investigated the correlation between hyperpolarization-activated current (1(h)) and menthol-activated current (I(TRPM8)) in rat dorsal root ganglion (DRG) neurons. We showed that I(h) is present in 89% of menthol-sensitive neurons which makes its presence reliable, though not absolute, criterion for pre-selection of such neurons. Endogenous I(h) recorded from different neurons exhibited variable density and activation kinetics. Based on the analysis of I(h) activation kinetics we hypothesize that the population of hyperpolarization-activated channels in menthol-sensitive DRG neurons is mainly represented by HCN1, HCN2 and HCN3 channels. The expression of HCN4 isoform in these cells is very low.
PubMed ID
18756770 View in PubMed
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Are young female gymnasts malnourished? An anthropometric, electrophysiological, and histological study.

https://arctichealth.org/en/permalink/ahliterature62367
Source
Eur J Appl Physiol Occup Physiol. 1984;52(4):457-62
Publication Type
Article
Date
1984
Author
C F Lindboe
M. Slettebø
Source
Eur J Appl Physiol Occup Physiol. 1984;52(4):457-62
Date
1984
Language
English
Publication Type
Article
Keywords
Adolescent
Adult
Anthropometry
Body Weight
Comparative Study
Electrophysiology
Female
Gymnastics
Humans
Muscles - pathology - physiology
Nutrition Disorders - diagnosis - pathology
Research Support, Non-U.S. Gov't
Abstract
Competitive rhythmic sportive gymnastics have been accused of promoting an unphysiologic weight reduction which may progress to manifest anorexia nervosa. In this study, eight young female gymnasts who represented Norway in the European Championships in Rhythmic Sportive Gymnastics 1982 were examined for evidence of malnutrition. Ten girls, matched for age and height, served as controls. The examination included registration of anthropometric data (height, weight, and body-mass index), motor and sensory neurography and biopsies of the vastus lateralis muscle with exact measurements of muscle fibre areas on sections stained for myofibrillar ATPase activity. The mean body weight of the gymnasts did not differ from that of the control group or of a large series of age matched Norwegian females. This finding excludes the possibility of general malnutrition among the examined gymnasts. Muscle fibres of both types 1 and 2 were found to be smaller in the gymnasts than in the controls, with values of 3,404 microns2 vs 3,811 microns2 for type-1 fibres and 2,985 microns2 vs 3,942 microns2 for type-2 fibres respectively. Although contradictory to most previous reports, this finding suggests that the reduction in fibre size among the gymnasts might be an effect of physical training. There were some differences in neurographic parameters between the groups, but the mean values were all within normal ranges. The motor nerve conduction velocity in the proximal segments of the median and ulnar nerves was significantly slower in the gymnasts and, as a possible consequence of smaller muscle fibres, the motor responses were generally less in this group.
PubMed ID
6540676 View in PubMed
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Atrial fibrillation: basic and clinical research at the Montreal Heart Institute.

https://arctichealth.org/en/permalink/ahliterature172374
Source
Can J Cardiol. 2005 Oct;21(12):1091-6
Publication Type
Article
Date
Oct-2005
Author
Denis Roy
Mario Talajic
Marc Dubuc
Bernard Thibault
Peter G Guerra
Laurent Macle
Pierre Gagné
Paul Khairy
Stanley Nattel
Author Affiliation
Department of Medicine and Research Centre, Montreal Heart Institute, Faculty of Medicine, University of Montreal, Quebec. d-roy@icm-mhi.com
Source
Can J Cardiol. 2005 Oct;21(12):1091-6
Date
Oct-2005
Language
English
Publication Type
Article
Keywords
Academies and Institutes
Anti-Arrhythmia Agents - therapeutic use
Anticoagulants - therapeutic use
Atrial Fibrillation - physiopathology - therapy
Biomedical Research - trends
Canada
Cardiac Catheterization
Cryosurgery
Electrophysiologic Techniques, Cardiac
Embolism - etiology - physiopathology - prevention & control
Heart Rate - drug effects
Humans
Abstract
The present article reviews pertinent contributions from the Montreal Heart Institute, Montreal, Quebec, to the understanding of the mechanisms and treatment of atrial fibrillation. The article discusses the usefulness of anticoagulant therapy, antiarrhythmic drug therapy for sinus rhythm maintenance, the electrophysiological basis of atrial fibrillation and the investigation of new energy sources for catheter ablation. Future directions at the Montreal Heart Institute are also briefly addressed.
PubMed ID
16234895 View in PubMed
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Atrial fibrillation--new aspects on mechanism and treatment.

https://arctichealth.org/en/permalink/ahliterature54716
Source
J Intern Med. 1996 Jan;239(1):3-15
Publication Type
Article
Date
Jan-1996
Author
S B Olsson
Author Affiliation
Department of Cardiology, University Hospital, Lund, Sweden.
Source
J Intern Med. 1996 Jan;239(1):3-15
Date
Jan-1996
Language
English
Publication Type
Article
Keywords
Animals
Anti-Arrhythmia Agents - therapeutic use
Atrial Fibrillation - complications - drug therapy - physiopathology - therapy
Cardiac Pacing, Artificial
Clinical Trials
Electric Countershock
Electrophysiology
Humans
Research Support, Non-U.S. Gov't
Abstract
During recent years, the exploration of different aspects of atrial fibrillation (AF) has become increasingly interesting. Thus, knowledge about basic underlying mechanisms, consequences and different modes of treatment has rapidly expanded. At a meeting in Lund, Sweden, in 1993, scientists within different fields of AF research gathered for the exchange of information. This paper is a short summary of some topics discussed at the Lund meeting and some suggestions as to how further research in this field may help to improve our understanding of this arrhythmia and the treatment of patients suffering from it. Underlying pathoelectrophysiological mechanisms in AF have been explored in experimental models in animals and by direct recordings of different atrial myocardial electrophysiological variables both in the catheter laboratory and during open heart surgery in man. Some findings illustrate possible generalized atrial myocardial mechanisms, whilst other findings clearly indicate the possibility of localized pathoelectrophysiological mechanisms. The generally accepted hypothesis that AF is perpetuated by multiple re-entry mechanisms is, thus, both verified and modified by recent studies. In addition to subjective symptoms and well identified thromboembolic consequences, accumulating evidence tells us that AF may precipitate a myocardial dysfunction which may be misinterpreted as an underlying factor initiating the arrhythmia. Today's treatment of AF includes several newer antiarrhythmic drugs, different ablation techniques, the application of different electrical devices as well as different surgical methods. New, improved and simplified methods are expected. Atrial fibrillation is the single most important supraventricular arrhythmia needing substantial further exploration of mechanisms, consequences and treatment. The Lund symposium contributed to this process by defining the state of knowledge in 1993 and outlining the need for the years to come.
PubMed ID
8551197 View in PubMed
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Atrioventricular nodal reentrant tachycardia treatment using novel potential.

https://arctichealth.org/en/permalink/ahliterature138682
Source
Asian Cardiovasc Thorac Ann. 2010 Dec;18(6):529-35
Publication Type
Article
Date
Dec-2010
Author
Andrey V Ardashev
Alexandr S Makarenko
Eugeny G Zhelyakov
Andrey A Shavarov
Author Affiliation
Clinical Hospital of Federal Biomedical Agency of Russia, Moscow, Russia. ardashev@yahoo.com
Source
Asian Cardiovasc Thorac Ann. 2010 Dec;18(6):529-35
Date
Dec-2010
Language
English
Publication Type
Article
Keywords
Action Potentials
Adult
Case-Control Studies
Catheter Ablation - adverse effects - methods
Electrocardiography
Electrophysiologic Techniques, Cardiac
Female
Heart Conduction System - physiopathology
Humans
Male
Middle Aged
Moscow
Tachycardia, Atrioventricular Nodal Reentry - physiopathology - surgery
Time Factors
Treatment Outcome
Abstract
Radiofrequency ablation of atrioventricular nodal reentrant tachycardia is commonly guided by slow and sharp bipolar potentials of the atrioventricular slow nodal pathway. We optimized the morphology of the guiding potential by unipolar mapping of the slow nodal pathway. We identified a novel unipolar dual-component atrial electrogram at the anterior limb of the coronary sinus ostium. The first component was a positive delta-wave type that corresponded to the isoelectric phase on a bipolar electrogram. The second component had fast biphasic morphology and corresponded to the R wave on a bipolar atrial electrogram. Of 104 consecutive patients with typical atrioventricular nodal reentrant tachycardia, 51 were treated with ablation guided by the novel potential, and 53 underwent ablation using the conventional technique. There was no recurrence of tachycardia in any of these patients. In those treated by the novel potential, there was significantly less radiofrequency power applied and a shorter duration of application than in patients treated by the traditional approach. The novel approach to mapping and ablation of the slow nodal pathway in atrioventricular nodal reentrant tachycardia guided by unipolar recording was safe and effective, and comparable to the traditional technique.
PubMed ID
21149400 View in PubMed
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Autosomal recessive spastic ataxia of Charlevoix-Saguenay.

https://arctichealth.org/en/permalink/ahliterature203834
Source
Neuromuscul Disord. 1998 Oct;8(7):474-9
Publication Type
Article
Date
Oct-1998
Author
J P Bouchard
A. Richter
J. Mathieu
D. Brunet
T J Hudson
K. Morgan
S B Melançon
Author Affiliation
Département des Sciences Neurologiques, Centre Hospitalier Affilié Universitaire de Québec, Canada.
Source
Neuromuscul Disord. 1998 Oct;8(7):474-9
Date
Oct-1998
Language
English
Publication Type
Article
Keywords
Ataxia - epidemiology - genetics - pathology
Chromosome Mapping
Chromosomes, Human, Pair 13 - genetics
Electrophysiology
Female
Genes, Recessive - genetics
Humans
Male
Microsatellite Repeats
Muscles - innervation - pathology - physiopathology
Quebec - epidemiology
Abstract
A form of autosomal recessive spastic ataxia unique to the Charlevoix-Saguenay area was clinically identified 20 years ago in patients from that region. This region of Québec, Canada, was once considered a genetic isolate. First noted at gait initiation, signs of ataxia slowly progress along with spasticity of the four limbs, slurred speech, and followed by distal amyotrophy. Early diagnosis relies on the presence of prominent myelinated fibers embedding retinal blood vessels at funduscopy and marked saccadic alteration of ocular smooth pursuit. Imaging of the posterior fossa shows cerebellar vermis atrophy and nerve conduction studies reveal loss of sensory and reduced motor conduction velocities. The clinical features are consistent with a developmental defect in myelination of both retinal and peripheral nerve fibers. The cause of this defect and the progressive axonal degeneration in the corticospinal and spinocerebellar tracts, as well as in the peripheral nerves is still unknown. Results of recent molecular genetic linkage analysis have located the gene locus to chromosome 13q12. Further research is needed to define where this hereditary spastic ataxia stands in the classification of the early onset spinocerebellar degenerations.
PubMed ID
9829277 View in PubMed
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Band-pass filtering by voltage-dependent membrane in an insect photoreceptor.

https://arctichealth.org/en/permalink/ahliterature51200
Source
Neurosci Lett. 1993 May 14;154(1-2):84-8
Publication Type
Article
Date
May-14-1993
Author
M. Juusola
M. Weckström
Author Affiliation
Department of Physiology, University of Oulu, Finland.
Source
Neurosci Lett. 1993 May 14;154(1-2):84-8
Date
May-14-1993
Language
English
Publication Type
Article
Keywords
Adaptation, physiological - physiology
Animals
Diptera - physiology
Electrophysiology
Fourier Analysis
Light
Membrane Potentials - physiology
Membranes - physiology
Photoreceptors - physiology
Potassium Channels - physiology
Abstract
The membrane properties of short type blowfly photoreceptors (R1-6) were investigated in dark and light adaptation with single electrode current and voltage clamp techniques. The impedance of the cells was defined in frequency domain by using discontinuous current clamp and white-noise-modulated current injection. We found that the slow activation and relaxation of the voltage-dependent K+ conductance transform the photoreceptor membrane effectively into a band-pass filter. This behaviour could be observed under current clamp as voltage-dependent outward and inward rectification of the membrane. The voltage-dependent band-pass filtering is likely to be present in all neurons with graded potentials and voltage-dependent membrane conductances.
PubMed ID
8361652 View in PubMed
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115 records – page 1 of 12.