PubMed Health⌕ Search

Biomedical subjects

James M Gilchrist

Publications and source records attributed to James M Gilchrist.

11 recordsLinked to original sources
PubMed2007

Safety of nerve conduction studies in patients with implanted cardiac devices.

Patients with implanted cardiac devices and their physicians may defer important electrodiagnostic testing because of anxiety about potential negative effects on the device. To determine the safety of routine nerve conduction studies (NCS) in this population, 10 patients with permanent dual-chamber pacemakers of various types and five patients with implanted cardiac defibrillators (ICD) underwent nerve stimulation at sites commonly used during NCS. The implanted cardiac device was interrogated before and after the study and there was continuous monitoring of the surface electrocardiogram (ECG) and atrial and ventricular electrograms. Electrical impulses generated during routine NCS were never detected by the sensing amplifier and did not affect the programmed settings of the implanted cardiac device. We conclude that routine NCS is safe in patients with implanted cardiac pacemakers with bipolar sensing configurations and defibrillators.

Arrhythmias, Cardiac↗
PubMed2005

Muscle carnitine in hypo- and hyperthyroidism.

Weakness is common in both hyper- and hypothyroidism, and skeletal muscle L-carnitine may play a role in this regard, as suggested by studies indicating abnormal levels of carnitine in serum and urine of patients with thyroid dysfunction. Skeletal muscle samples were obtained for carnitine analysis from control subjects, and from hyperthyroid and hypothyroid patients before and after treatment. There was a significant reduction in carnitine, especially the esterified portion, in hyperthyroid individuals, with a return to normal as euthyroid status was regained. In hypothyroid patients, there was a trend for carnitine to be lower than normal and for improvement once euthyroid status was attained. Our data indicate that muscle carnitine levels are affected by both hypo- and hyperthyroidism. A decrease in muscle carnitine in both conditions may contribute to thyroid myopathy.

Adult↗
PubMed2005

Use of the Hermann grid illusion in the measurement of contrast perception in dyslexia.

We measured contrast thresholds for perception of the Hermann grid illusion, using different contrast polarities and mean luminances, in dyslexics and non-dyslexics. Both groups of subjects gave significantly lower thresholds with grids having dark squares and light paths, but there was no significant threshold difference between groups. Perceived strength of illusion was also measured in grids at suprathreshold contrast levels. Dyslexics perceived the illusion to be significantly stronger than non-dyslexics when the grid had light paths and low luminance.

Adolescent↗
PubMed2005

Comparing and unifying slope estimates across psychometric function models.

The psychometric function relating stimulus intensity to response probability generally presents itself as a monotonically increasing sigmoid profile. Two summary parameters of the function are particularly important as measures of perceptual performance: the threshold parameter, which defines the location of the function over the stimulus axis (abscissa), and the slope parameter, which defines the (local) rate at which response probability increases with increasing stimulus intensity. In practice, the psychometric function may be modeled by a variety of mathematical structures, and the resulting algebraic expression describing the slope parameter may vary considerably between different functions fitted to the same experimental data. This variation often restricts comparisons between studies that select different functions and compromises the general interpretation of slope values. This article reviews the general characteristics of psychometric function models, discusses three strategies for resolving the issue of slope value differences, and presents mathematical expressions for implementing each strategy.

Humans↗
PubMed2004

Electrodiagnostic studies in the management and prognosis of neuromuscular disorders.

Prognosis remains a neglected aspect of modern medical care and research, behind diagnosis and treatment. The very term "electrodiagnosis" implies as much. Despite this, much has been published regarding the use and benefit of electrodiagnostic techniques in assessing prognosis and assisting in management of patients after the diagnosis has been established. This information is often hidden or otherwise not emphasized. This review summarizes the literature regarding the use of such techniques for prognosis and management of disorders of lower motor neurons, peripheral nerves, neuromuscular transmission, and muscle.

Action Potentials↗
PubMed2002

Ratings of subjective mental fatigue relate to cognitive performance in patients with myasthenia gravis.

We examined ratings of fatigue and cognitive performance in myasthenia gravis (MG) patients and healthy subjects. All participants were administered self-report measures of mental and physical fatigue before and after completing a demanding cognitive work battery. Change in fatigue indices was recorded and examined in relation to cognitive function. Results of the study revealed that baseline ratings of fatigue did not relate to cognitive performances for either group. By contrast, increased mental fatigue from the baseline to the post-test assessment correlated with cognitive measures for patients but not control subjects. MG patients reported that physical fatigue also increased following the work battery, but only ratings of mental fatigue correlated with cognitive performances. The results indicate that cognitive impairments may be associated with perceived fatigue in MG.

Aged↗
PubMed2002

Overview of neuromuscular disorders affecting respiratory function.

A great many neuromuscular disorders affect respiratory function. This article focuses on neuropathic and myopathic disorders that weaken the diaphragm and respiratory muscles. This discussion gives a general overview and attempts to update the reader on recent pathophysiological insights and developments in therapy. Among the disorders discussed, amyotrophic lateral sclerosis, poliomyelitis, postpolio syndrome, Kennedy syndrome, and spinal muscular atrophy are motor neuron diseases. Brachial plexitis and isolated unilateral or bilateral phrenic neuropathies can also weaken the diaphragm significantly. Peripheral neuropathies affecting respiration are primarily acute disorders such as Guillain-Barré syndrome, porphyria, and critical illness neuropathy, but chronic diseases such as chronic inflammatory demyelinating polyneuropathy (CIDP) and Charcot-Marie-Tooth disease (CMT) can also cause respiratory insufficiency. Disorders of neuromuscular transmission such as Lambert-Eaton syndrome, botulism, and myasthenia gravis often affect respiration. Many muscle diseases also affect pulmonary function, including polymyositis/dermatomyositis, muscular dystrophy, hereditary channel disorders, mitochondrial encephalomyopathies, acid maltase deficiency, and congenital myopathy.

Journal Article↗
PubMed2002

Muscle disease.

Explore the source record for details and available documents.

Female↗