Janice M. Massey

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 αβ-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.

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.

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 δ 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.

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.

The ultrasonographic wrist-to-forearm median nerve area ratio in carpal tunnel syndrome

OBJECTIVE Peripheral nerve ultrasound is an emerging tool in the diagnosis of carpal tunnel syndrome (CTS). Although numerous publications have cited an increased median nerve area at the wrist to be the diagnostic of CTS, there has been considerable variability in the published normal values for this measurement. Our objective is to collect data on the wrist-to-forearm ratio (WFR) of median nerve area in patients with CTS and healthy controls. METHODS Patients with electrodiagnostically proven CTS underwent ultrasonography of the median nerve at the wrist and forearm. The median nerve area was measured at these points and compared to values from asymptomatic volunteers. RESULTS The WFR of median nerve area in asymptomatic volunteers was 1.0+/-0.1. The WFR in patients presenting with CTS was 2.1+/-0.5. CONCLUSIONS The WFR in patients with CTS is elevated as compared to asymptomatic controls. A WFR of 1.4 gave 100% sensitivity for detecting patients with CTS while using only median nerve area at the wrist resulted in a sensitivity of 45-93%, depending on the cut-off value used. SIGNIFICANCE The WFR of median nerve area promises to be a valid means of diagnosing CTS, and may be superior to measuring median nerve area at the wrist alone.

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.

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.

Randomized Trial of Thymectomy in Myasthenia Gravis

BACKGROUND Thymectomy has been a mainstay in the treatment of myasthenia gravis, but there is no conclusive evidence of its benefit. We conducted a multicenter, randomized trial comparing thymectomy plus prednisone with prednisone alone. METHODS We compared extended transsternal thymectomy plus alternate-day prednisone with alternate-day prednisone alone. Patients 18 to 65 years of age who had generalized nonthymomatous myasthenia gravis with a disease duration of less than 5 years were included if they had Myasthenia Gravis Foundation of America clinical class II to IV disease (on a scale from I to V, with higher classes indicating more severe disease) and elevated circulating concentrations of acetylcholine-receptor antibody. The primary outcomes were the time-weighted average Quantitative Myasthenia Gravis score (on a scale from 0 to 39, with higher scores indicating more severe disease) over a 3-year period, as assessed by means of blinded rating, and the time-weighted average required dose of prednisone over a 3-year period. RESULTS A total of 126 patients underwent randomization between 2006 and 2012 at 36 sites. Patients who underwent thymectomy had a lower time-weighted average Quantitative Myasthenia Gravis score over a 3-year period than those who received prednisone alone (6.15 vs. 8.99, P<0.001); patients in the thymectomy group also had a lower average requirement for alternate-day prednisone (44 mg vs. 60 mg, P<0.001). Fewer patients in the thymectomy group than in the prednisone-only group required immunosuppression with azathioprine (17% vs. 48%, P<0.001) or were hospitalized for exacerbations (9% vs. 37%, P<0.001). The number of patients with treatment-associated complications did not differ significantly between groups (P=0.73), but patients in the thymectomy group had fewer treatment-associated symptoms related to immunosuppressive medications (P<0.001) and lower distress levels related to symptoms (P=0.003). CONCLUSIONS Thymectomy improved clinical outcomes over a 3-year period in patients with nonthymomatous myasthenia gravis. (Funded by the National Institute of Neurological Disorders and Stroke and others; MGTX ClinicalTrials.gov number, NCT00294658.).

Mycophenolate mofetil for myasthenia gravis: An analysis of efficacy, safety, and tolerability

The authors report a retrospective analysis of the use of mycophenolate mofetil (MyM) in 85 patients with autoimmune myasthenia gravis. The Myasthenia Gravis Foundation of America (MGFA) postintervention status (PIS) was used to characterize the treatment response in each patient. Sixty-two patients (73%) achieved a PIS status indicating improvement. Quantitative strength testing performed on the majority of patients before and after treatment also improved. Side effects to MyM were observed in 27% of patients but required discontinuation in only 6%.

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.