PubMed Health⌕ Search

Biomedical subjects

J M Massey

Publications and source records attributed to J M Massey.

At least 19 recordsLinked to original sources
PubMed2003

Clinical aspects of MuSK antibody positive seronegative MG.

Serum antibodies to muscle-specific receptor tyrosine kinase were detected in 12 of 32 patients with generalized seronegative MG. All were women, with onset between ages 21 and 59 years. Seven had prominent neck, shoulder, or respiratory muscle weakness and little or delayed ocular muscle involvement. The response to cholinesterase inhibitors was variable, and electromyographic findings suggested myopathy in several. None improved after thymectomy. All patients improved after plasma exchange, and most had a good response to selected immunotherapy. MuSK antibody status should help diagnose MG with atypical presentations and ensure appropriate patient treatment.

Adult↗
PubMed2001

Mycophenolate mofetil for myasthenia gravis: an open-label pilot study.

In an open-label study, 12 patients with refractory MG or who were taking only corticosteroids and required additional immunosuppression received mycophenolate mofetil 1 g twice daily for 6 months. A reduction of three points in a quantified MG score and two points in a manual muscle test or a reduction of 50% in corticosteroid dose defined efficacy. Eight patients improved, beginning after 2 weeks to 2 months. No major side effects were observed.

Adult↗
PubMed2000

Retrospective analysis of the use of cyclosporine in myasthenia gravis.

The authors reviewed the records of patients with myasthenia gravis who took cyclosporine for at least 6 months between November 1987 and January 1999. Of 57 patients who took cyclosporine for an average of 3.5 years, 55 (96%) had clinical improvement. The median time to best clinical response was 7 months. Corticosteroids were discontinued or decreased in 95% of 38 patients taking them. Major side effects included elevated serum creatinine (28%) and malignancy (11%). Five percent could not afford or tolerate the drug.

Adult↗
PubMed2000

Lambert-Eaton myasthenic syndrome: electrodiagnostic findings and response to treatment.

The authors reviewed the incidence of cancer, repetitive nerve stimulation findings, and response to treatment in 73 patients with Lambert-Eaton myasthenic syndrome. Thirty-one patients (42%) had lung cancer, 29 small cell. Doubling of the compound motor action potential amplitude in three tested distal muscles was seen in only 41% of patients. Treatment with 3, 4-diaminopyridine produced moderate to marked self-reported functional improvement in 79% of the 53 treated patients.

4-Aminopyridine↗
PubMed2000

Leukemia inhibitory factor, oncostatin M, IL-6, and stem cell factor mRNA expression in human thymus increases with age and is associated with thymic atrophy.

The roles that thymus cytokines might play in regulating thymic atrophy are not known. Reversing thymic atrophy is important for immune reconstitution in adults. We have studied cytokine mRNA steady-state levels in 45 normal human (aged 3 days to 78 years) and 34 myasthenia gravis thymuses (aged 4 to 75 years) during aging, and correlated cytokine mRNA levels with thymic signal joint (sj) TCR delta excision circle (TREC) levels, a molecular marker for active thymopoiesis. LIF, oncostatin M (OSM), IL-6, M-CSF, and stem cell factor (SCF) mRNA were elevated in normal and myasthenia gravis-aged thymuses, and correlated with decreased levels of thymopoiesis, as determined by either decreased keratin-positive thymic epithelial space or decreased thymic sjTRECs. IL-7 is a key cytokine required during the early stages of thymocyte development. Interestingly, IL-7 mRNA expression did not fall with aging in either normal or myasthenia gravis thymuses. In vivo administration of LIF, OSM, IL-6, or SCF, but not M-CSF, i.p. to mice over 3 days induced thymic atrophy with loss of CD4+, CD8+ cortical thymocytes. Taken together, these data suggest a role for thymic cytokines in the process of thymic atrophy.

Adolescent↗
PubMed2000

A randomized trial of 3,4-diaminopyridine in Lambert-Eaton myasthenic syndrome.

OBJECTIVES: The authors report the results of a prospective, placebo-controlled, randomized study to evaluate the effectiveness of 3,4-diaminopyridine (DAP) in patients with Lambert-Eaton myasthenic syndrome (LEMS) and to determine the acute and long-term side effects of DAP. METHODS: Twenty-six patients with LEMS completed a two-arm parallel treatment protocol in which DAP, 20 mg three times daily, or placebo was given blindly for 6 days, and a quantitative examination of muscle strength (the quantitative myasthenia gravis [QMG] score) was used as the primary measure of efficacy. After the blinded study, patients were given open-label DAP and monitored for side effects as long as there was symptomatic improvement. RESULTS: Twelve patients took DAP, and 14 took placebo. There was no difference in the age of LEMS onset, gender distribution, incidence of lung cancer, or baseline muscle strength between the patients who were randomly assigned to receive placebo and those randomly assigned to DAP. Statistical analysis using the Wilcoxon's rank sum test demonstrated that patients who received DAP had a significantly greater improvement in the QMG score and in the summated amplitude of compound muscle action potentials recorded from three sentinel limb muscles. All but one LEMS patient had significant symptomatic improvement from subsequent open-label DAP. Side effects of DAP were negligible, consisting of perioral and digital paresthesia. Laboratory measurements demonstrated no evidence of toxicity affecting liver, renal, hematologic, endocrinologic, encephalographic, or electrocardiologic function acutely or after 6 months of open-label DAP. CONCLUSIONS: This study corroborates previous studies and many years of clinical experience showing that DAP is an effective and safe treatment for LEMS.

4-Aminopyridine↗
PubMed1998

Changes in thymic function with age and during the treatment of HIV infection.

The thymus represents the major site of the production and generation of T cells expressing alphabeta-type T-cell antigen receptors. Age-related involution may affect the ability of the thymus to reconstitute T cells expressing CD4 cell-surface antigens that are lost during HIV infection; this effect has been seen after chemotherapy and bone-marrow transplantation. Adult HIV-infected patients treated with highly active antiretroviral therapy (HAART) show a progressive increase in their number of naive CD4-positive T cells. These cells could arise through expansion of existing naive T cells in the periphery or through thymic production of new naive T cells. Here we quantify thymic output by measuring the excisional DNA products of TCR-gene rearrangement. We find that, although thymic function declines with age, substantial output is maintained into late adulthood. HIV infection leads to a decrease in thymic function that can be measured in the peripheral blood and lymphoid tissues. In adults treated with HAART, there is a rapid and sustained increase in thymic output in most subjects. These results indicate that the adult thymus can contribute to immune reconstitution following HAART.

Adolescent↗
PubMed1997

Acquired myasthenia gravis.

Myasthenia gravis, an antibody-mediated disorder of neuromuscular transmission that produces clinical weakness, may be ocular or generalized. Clinical diagnostic evaluation may be supplemented by electrophysiologic studies and antibody testing. Therapeutic options, including anticholinesterase inhibitors, immunosuppressive agents, plasmapheresis and thymectomy, are tailored for the individual patient. This article emphasizes the key aspects of the clinical evaluation, diagnosis, and therapy.

Autoantibodies↗
PubMed1997

Botulinum toxin type B: a double-blind, placebo-controlled, safety and efficacy study in cervical dystonia.

We enrolled and treated 122 patients with idiopathic cervical dystonia in a double-blind, placebo-controlled safety and efficacy study of botulinum toxin type B (BotB). Both A-responsive and A-resistant patients were enrolled. Patients received intramuscular injections of either BotB (2,500 U, 5,000 U, or 10,000 U) or placebo. The primary outcome measure of efficacy was the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS)-Total score at 4 weeks following study drug administration. Secondary measures of efficacy were TWSTRS-Severity, -Disability, and -Pain subscale scores, and Analog Pain Assessment, Investigator Global Assessment, Patient Global Assessment, and Sickness Impact Profile scores. Duration of effect was estimated with an intent-to-treat analysis of responders. Safety measures included clinical parameters, laboratory tests, and adverse events. The primary and most of the secondary analyses indicated a statistically significant treatment effect and a dose response. BotB is safe, well tolerated, and efficacious in the treatment of cervical dystonia at the doses tested.

Adult↗
PubMed1994

Single fiber EMG and repetitive stimulation of the same muscle in myasthenia gravis.

We performed RNS and SFEMG studies of the same muscle in 46 patients with myasthenia gravis. Maximum decrement to 3-5-Hz stimulation before and after maximum voluntary exercise, percentage of action potential pairs with increased jitter and blocking, and mean MCD in each study were compared. A significant decrement (> 10% decrease in CMAP area or amplitude between the first and fourth response) was never found without increased jitter and impulse blocking on SFEMG. Increased jitter, blocking, and mean MCD were each correlated with maximum decrement (r > 0.61, P < 0.0001). We conclude that decrement to RNS and impulse blocking on SFEMG result from the same physiologic phenomenon, and that SFEMG is more sensitive at detecting disordered neuromuscular transmission given its ability to detect impulse blocking at levels below the resolution of RNS and increased neuromuscular jitter when there is not blocking.

Adolescent↗
PubMed1994

Race, sex, and puberty influence onset, severity, and outcome in juvenile myasthenia gravis.

We assessed the influence of race, sex, and puberty upon clinical features and outcome in 115 patients with autoimmune juvenile myasthenia gravis (JMG). These demographic variables influenced not only disease incidence but also disease severity, response to therapy, and outcome, despite comparable therapeutic strategies. Among white patients, those with prepubertal onset had low incidence and equal sex ratio; the incidence in females increased during and after puberty; males had lesser disease severity than females during and after puberty (p < 0.05); spontaneous remissions were most frequent (44%, p = 0.001) and persistence of active JMG for more than 10 years was least frequent (p = 0.05) in patients with prepubertal onset; remissions were more frequent after early than late thymectomy (p = 0.03); and final disease severity was less after early than late thymectomy. Black patients had similar incidence, disease severity, and sex ratio (F:M = 2:1) with pre-, peri-, or postpubertal disease onset; infrequent spontaneous or treatment-induced remissions; and the same final disease severity after early or late thymectomy. These observations imply that race and sex hormones modify the clinical features and outcome of JMG; spontaneous remissions are common in white patients with prepubertal disease onset; early thymectomy may be more beneficial than late thymectomy in white patients; and the role of thymectomy in the youngest patients is uncertain. We suggest that demographic factors should be considered when evaluating past and future therapeutic strategies for JMG.

Adolescent↗
PubMed1994

The electrodiagnosis of myasthenia gravis and the Lambert-Eaton myasthenic syndrome.

Electrodiagnostic studies are valuable in confirming the diagnosis of a disorder of neuromuscular transmission. They are used to distinguish presynaptic and postsynaptic abnormalities. These studies provide an objective measure of the severity of the illness and may be useful in assessing the response to therapy. This article reviews the electrodiagnostic techniques that are commonly used today and highlights their specificity, sensitivity, and pitfalls.

Electromyography↗