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Interleukin 10 (IL-10) is secreted by several hemopoietic cells and suppresses the Th1 mediated immune response, while stimulating B cell differentiation and the humoral immune response. IL-10 expression in Con A-stimulated peripheral blood mononuclear cells is related to three polymorphisms in the promoter region of the IL-10 gene; G/A at position -1082, T/C at position -819 and A/C at position -592. We analyzed the distribution of these IL-10 polymorphisms in 64 MG patients and 87 healthy blood donors to determine any influence on MG susceptibility. MG patients had a significantly higher frequency of the ACC/ACC haplotype (12.5% vs 3.4% in controls), as had the subgroups with late onset MG and thymomatous MG (20.0% and 21.4%, respectively). Early onset MG patients had a high frequency of the ATA/ATA haplotype (19.2% vs 3.4% in controls). Titin Ab-positive MG patients had high ACC/ACC (20.0%). This study indicates a direct link between IL-10 and MG pathogenesis, although the complex role of this multi-faceted cytokine in vivo is as yet not fully elucidated.

Paraneoplastic myasthenia gravis (MG) is accompanied by a neoplasm, usually thymoma. In patients with thymoma and a specific genetic make-up, the paraneoplastic immune response develops further in thymic remnant or peripheral lymphatic tissue. Paraneoplastic MG and late-onset MG (age >or= 50 years) share a similar immunological profile with high titin and ryanodine receptor (RyR) antibody prevalence. This profile is the most important predictor of clinical outcome in paraneoplastic MG. The presence of a thymoma per se does not cause more severe MG. MG severity is linked to the patient's immunological profile. Paraneoplastic MG causes a distinctive non-limb symptom profile at MG onset, characterized by bulbar, ocular, neck, and respiratory symptoms. When the diagnosis of paraneoplastic MG is established, the neoplasm should be removed surgically. Pre-thymectomy plasmapheresis or iv-IgG should be considered in these patients to minimize post-thymectomy MG exacerbation risk. Paraneoplastic MG usually continues after thymectomy. The pharmacological treatment of paraneoplastic MG does not differ from non-paraneoplastic MG, except for tacrolimus that should be considered in difficult cases. Tacrolimus is an immunosuppressant acting specifically in RyR antibody positive patients through enhancing RyR-related sarcoplasmic calcium release that in theory might be blocked by RyR antibodies, causing symptomatic relief in paraneoplastic MG.

Of sera of patients with myasthenia gravis (MG), 30% contains titin and ryanodine receptor (RyR) antibodies. In early-onset MG (i.e., before 50 years of age), the presence of titin antibodies strongly suggests a thymoma. Late-onset MG comprises one MG group, characterized by a broad antimuscle immune response, including both titin and the acetylcholine receptor (AChR). Another group is preferentially associated with the HLA-A3, B7 and DRw2 antigens, representing a delayed early-onset of the disease that has a selective AChR immune response. The presence of titin and RyR antibodies is associated with more severe disease. Titin antibodies may, in some patients with rippling muscle disease, affect the contractile machinery of myofibers, thereby affecting their mechanical sensitivity. It is not known whether this occurs in MG. RyR antibodies may impair excitation–contraction coupling and contribute to muscle weakness in MG patients. Titin antibodies may serve as tumor markers in early-onset MG patients.

The collapsin response mediator protein 5 (CRMP5) antibody is usually associated with paraneoplastic neurological syndrome (PNS) and small-cell lung cancer (SCLC) or thymoma. The objective of this study was to assess the frequency of CRMP5 antibodies in patients with such tumours and to see if the presence of antibodies was associated with prognosis in these cancers. A multi-well adapted immunoprecipitation assay using radiolabelled recombinant CRMP5 protein, produced by coupled in vitro transcription/translation, was used for the detection of CRMP5 antibodies. Sera from 200 patients with SCLC, 73 patients with thymoma and myasthenia gravis (MG) and from 300 healthy blood donors were examined for CRMP5 antibodies. Positive sera were also examined by immunofluorescence and immune blots. The serological results were compared with disease severity of the patients with thymoma or SCLC. CRMP5 antibodies were detected in 10/200 (5%) of the SCLC, 9/73 (12%) of the thymomas and in 2/300 (0.6%) of the healthy controls by immunoprecipitation. The antibodies were less frequently detected by immunofluorescence or immune blots. There was no significant correlation between CRMP5 antibodies and disease severity. CRMP5 antibodies are more than twice as frequent, and the antibody levels are higher in patients with thymoma and MG than in patients with SCLC. The antibodies are correlated to these tumours, but not to disease severity.

Hypokalemic pareses are caused by low extracellular potassium levels which reduce the resting membrane potential of muscle cells and make them less excitable. It may be caused by an intracellular shift of potassium, renal potassium loss, reduced potassium intake or increased gastrointestinal loss.A woman in her 60s presented with rapid-onset tetraparesis and hyporeflexia starting the day before admission. The patient history revealed several months of low food intake, increased alcohol consumption and diarrhoea. Laboratory tests showed severe hypokalemia (1.5 mmol/l) and hypomagnesemia (0.38 mmol/l), and ECG showed atrial fibrillation. She was admitted to the medical intensive care unit and treated with intravenous normal saline with added potassium and magnesium, with good effect on her symptoms. Urine tests showed high potassium-creatinine ratio (4.22 mmol/mmol creatinine) and increased fractional excretion of magnesium (18.6%). Abdominal CT scan revealed colonic wall thickening, and colonic biopsies showed mild inflammation. Faecal calprotectin was moderately elevated (294 mg/kg).The patient had hypokalemic pareses for which there were several contributing factors. The renal causes were augmented excretion of magnesium and potassium, probably due to increased alcohol consumption. The extrarenal causes were increased gastrointestinal loss, with ulcerative colitis being the presumed explanation, and reduced food intake.

Parkinson's disease (PD) may be associated with a number of different diseases due to common risk factors or overlapping symptomatology. We have asked for possible associated disorders in a Norwegian population of incident PD patients and controls, the Norwegian ParkWest study. The patients were diagnosed according to the Gelb criteria. 212 incident PD patients and 175 age and gender matched controls were included. PD patients and controls were asked for information on earlier medical history and family history. PD patients had a higher frequency of self-reported symptoms of depression (p = 0.003) and anxiety disorders (p = 0.004) before baseline. They tended to have a higher frequency of diabetes (p = 0.09) and had a higher frequency of prior stroke or TIA (p = 0.004).

Myasthenia gravis (MG) in individuals over 40 years of age comprises three groups: early-onset MG with prolonged disease duration, late-onset MG with thymoma, and late-onset of nonthymomatous MG. The clinical features do not differ between the three groups, except that early-onset patients with prolonged disease duration usually have a less severe disease. More than 60% of our MG patients are now more than 50 years of age, often with disease onset after age 40. Although 2 out of the 3 patients in Erb's original description had onset of myasthenic symptoms after age 40, this was apparently infrequent in 1879, when the disease was first identified. Onset of MG after age 40 is now common. For example, in our material, 88/184 (47.8%) had onset of MG after age 40. Eighteen (20.5%) had a thymoma. The female:male ratio in the early-onset group was 2.4:1, whereas it was 1:1.1 among those with onset after age 40. There was no human leukocyte antigen association for MG with thymoma. Antibodies to the acetylcholine receptor were detected in 88% of sera from nonthymomatous MG and in 100% of those with late-onset MG with thymoma. Antibodies to titin were found in sera from 85.7% of MG patients with thymoma (all age groups) and in 58% of nonthymomatous MG with late onset and acetylcholine receptor antibodies. Late-onset, nonthymomatous MG comprises two subgroups, one corresponding to delayed early onset and one immunologically similar to that seen in patients with MG and thymoma.

Some myasthenia gravis (MG) patients have antibodies against skeletal muscle antigens in addition to the acetylcholine receptor (AChR). Two major antigens for these antibodies are the Ca(2+) release channel of the sarcoplasmic reticulum, the ryanodine receptor (RyR), and titin, a gigantic filamentous muscle protein essential for muscle structure, function, and development. RyR and titin antibodies are found in MG patients with a thymoma and in a proportion of late-onset MG, and they correlate with severe MG disease. The RyR antibodies recognize a region near the N-terminus important for channel regulation. They inhibit Ca(2+) release from sarcoplasmic reticulum in vitro. There is electrophysiological evidence for a disordered excitation-contraction coupling in MG patients. The presence of titin antibodies, which bind to key regions near the A/I junction and in the central I-band, correlates with myopathy in MG patients. However, so far, there is no direct evidence that antibodies against the intracellular antigens RyR and titin are pathogenic in vivo.

Cortical-type thymomas are associated with myasthenia gravis (MG) in 50% of the cases. MG is caused by antibodies against the acetylcholine receptors (AChR), but additional non-AChR muscle autoantibodies such as those against titin and ryanodine receptor (RyR) are found in up to 95% of MG patients with thymoma. To elucidate the induction of non-AChR autoantibodies in thymoma-associated MG, we studied cortical-type thymomas from seven thymoma MG patients, and sera from six of them. All six had titin antibodies, and four had RyR antibodies. Titin and RyR epitopes were co-expressed along with LFA3 and B7 (BB1) costimulatory molecules on thymoma antigen-presenting cells (APC) in all thymomas. In normal thymus, the staining by anti-titin, anti-RyR, anti-LFA3, and anti-BB1 antibodies was weak and occurred exclusively in the medulla and perivascularly. Our results indicate a primary autosensitization against titin and RyR antigens inside the thymoma. In MG-associated thymoma, the mechanisms involved in the initial autosensitization against titin and RyR are probably similar to those implicated in the autosensitization against AChR. In all cases, there is an overexpression of muscle-like epitopes and costimulatory molecules indicating that the T-cell autoimmunization is actively promoted by the pathogenic microenvironment inside the thymoma.

Some myasthenia gravis (MG) patients have antibodies against skeletal muscle antigens in addition to the acetylcholine receptor (AChR). A major antigen for these antibodies is the Ca2+ release channel of the sarcoplasmic reticulum the ryanodine receptor (RyR). These antibodies are found mainly in MG patients with a thymoma MG and correlate with severe MG symptoms. The antibodies recognize a region near the N-terminus on the RyR, which seems to be of importance for RyR regulation. The antibodies cause allosteric inhibition of RyR function in vitro, inhibiting Ca2+ release from sarcoplasmic reticulum.

Some myasthenia gravis (MG) patients have antibodies against non-acetylcholine receptor (AChR) epitopes of skeletal muscle including titin. Peripheral blood lymphocytes from 11 MG patients and 13 blood-donors were tested for lymphocyte proliferation after stimulation with the titin peptide MGT-30, which represents the main immunogenic region. Four out of seven titin antibody positive patients had significant stimulation defined as a stimulation index (SI) above 2. Neither of the four titin antibody negative patients nor the 13 blood-donors had SI above 2 (p = 0.001). Mean SI was significantly higher for T-cells from titin antibody positive MG patients, SI = 2.2 ± 0.8, compared to titin antibody negative patients, SI = 0.9 ± 0.2 (p = 0.01), and blood-donors, SI = 0.8 ±0.3 (p > 0.0005). After MGT-30 stimulation, IL-4 was detected in the blood lymphocyte culture supernatant from four of the five MG patients examined, but from none of the eight blood-donors. Thus, MG patients with anti-titin antibodies have a T-cell mediated immune reaction against titin.

Twenty-two late-onset, non-thymoma myasthenia gravis (MG) patients were selected for study based on the combined presence of MG and involution of the thymus. Thymectomy specimens from all the patients were examined histologically and immunohistologically and compared with an age-matched control group in which tissue was removed from the thymic gland during operations for various cardiac conditions. We were not able to find any morphological differences between thymi from MG patients and patients in the control group. Germinal centres were present in 7/22 in the patient group and 6/20 in the control group. Seven of our 22 MG patients had auto-antibodies to titin. Germinal centres in the thymus were found in only one. In contrast germinal centres were present in the thymus of 6/15 MG patients with no detectable antibody response to titin (p= 0.01). Our study suggests that late-onset MG is pathogenetically heterogeneic with different modes of auto-sensitisation.

Myasthenia gravis (MG) patients with thymoma often have antibodies against the calcium-release channel of the sarcoplasmic reticulum (SR) in striated muscle, the ryanodine receptor (RyR). RyR function can be tested in vitro by measuring the degree of [3H]-ryanodine binding to SR. In this study, sera from 9 out of 14 MG patients containing RyR antibodies inhibited [3H]-ryanodine binding to SR membranes from rat skeletal muscle. The 9 patients with antibodies inhibiting ryanodine binding had more severe MG than those with noninhibiting antibodies (P = 0.006). Sera from MG patients with acetylcholine receptor and titin muscle antibodies but no antibodies against RyR and blood-donor sera did not have an inhibiting effect in the [3H]-ryanodine binding assay. The results show that RyR antibodies in MG patients have high affinity for the RyR, and that the binding of antibodies probably affects calcium release from SR by locking the RyR ion channel in a closed position.

Myasthenia gravis (MG) patients develop autoantibodies primarily against the acetylcholine receptor in the motor endplate, but also against intracellular striated muscle proteins, notably titin, the giant elastic protein of the myofibrillar cytoskeleton. Titin antibodies have previously been shown to be directed against a single epitope on the molecule, located at the A-band/I-band junction and referred to as the main immunogenic region (MIR) of titin. By using immunofluorescence microscopy on stretched single myofibrils, we now report that approximately 40% of the sera from 18 MG/thymoma patients and 8 late-onset MG patients with thymus atrophy contain antibodies that bind to a more central I-band titin region. This region consists of homologous immunoglobulin domains and is known to be differentially spliced dependent on muscle type. All patients with I-band titin antibodies also had antibodies against the MIR. Although a statistically significant correlation between the occurrence of I-band titin antibodies and MG severity was not apparent, the results could hint at an initial immunoreactivity to titin's MIR, followed by reactivity along the titin molecule in the course of the disease.

The Fc γ receptors, Fc γ RIIA and Fc γ RIIIB contain polymorphisms with different capacity for IgG binding and phagocytosis. Thirty myasthenia gravis (MG) patients and 49 healthy controls were genotyped for the Fc γ RIIA and Fc γ RIIIB polymorphisms using polymerase chain reaction. The frequency of the Fc γ RIIA-H/H genotype was increased in thymoma MG patients compared to other MG patients ( P =0.05) and controls ( P =0.02). The distribution of Fc γ RIIIB alleles in MG patients did not differ from the controls, but MG patients with the NA1/NA1 genotype had the most severe MG ( P =0.01). Levels of AChR-antibodies and frequency of titin or ryanodine receptor antibodies were not associated with the Fc γ RIIA or Fc γ RIIIB genotypes. The results suggest different pathogenetic mechanisms in paraneoplastic and non-paraneoplastic autoimmune MG.

Myasthenia gravis (MG) patients may have circulating autoantibodies against titin. In this study, we have stimulated T cells from MG patients with a recombinant polypeptide containing the main immunogenic region of titin, MGT-30 (myasthenia gravis titin-30 kDa). In an ELISpot assay, MGT-30 reactive interferon (IFN)-gamma secreting cells (Th1 cells) were detected in six of 10 titin antibody positive MG patients. Such cells were not detected in any of the five titin antibody negative MG patients or in the seven blood donors. In three patients, the stimulated number of cells decreased when total remission of MG symptoms was achieved after thymectomy or following a period of intensive immunosuppressive medication. We detected MGT-30 interleukin (IL)-4 secreting cells (Th2 cells) in two of five titin antibody positive MG patients, but not in the two titin antibody negative patients or the five blood donors examined. We conclude that titin antibody positive MG patients have a combined Th1/Th2 cell mediated immunity against the muscle protein titin.

Myasthenia gravis (MG) is mediated by autoantibodies against the acetylcholine receptor at the muscle endplate. Some MG patients have in addition antibodies (Ab) to the skeletal muscle proteins ryanodine receptor (RyR) and titin. We have examined GM and KM allotypes, RyR and titin Ab in 44 MG patients (37 thymoma patients and 7 non-thymoma, late-onset patients) and 292 non-MG controls to see if GM/KM allotypes associate with differences in autoantibody production. All patients had titin Ab, and 15 thymoma patients had also RyR Ab. The phenotype GM 1, 2, 3 23 5, 21 was significantly increased in the patients with titin Ab compared with the non-MG controls (chi2 = 4.93, p0.05). Thymoma patients with RyR Ab had a higher frequency of the GM 3 23 5 phenotype compared with RyR Ab negative patients and controls (chi2 = 7.1, p0.05). KM allotypes did not differ between RyR Ab positive or titin Ab positive patients and controls. GM phenotypes may thus be associated with an autoimmune response against the muscle proteins titin and RyR in MG patients.

Sera from 32 thymoma patients, 29 of them with myasthenia gravis (MG), were tested for the presence of circulating antibodies to the ryanodine receptor (RyR) in Western blot RyR is a channel protein essential for the excitation-contraction coupling in skeletal muscle. MG severity was scored according to the Osserman classification during 1–17 years of follow-up (mean 7 years). Fifteen patients (14 MG and 1 non-MG) were RyR-antibody positive. RyR-positive patients had a significantly higher frequency of invasive thymomas (p = 0.01), and also a more severe MG than RyR-antibody negative patients (p = 0.04). The use of immunosuppressive drugs at latest follow-up was more frequent in RyR-antibody positive than in RyR-antibody negative patients (p = 0.02). Thus the presence of RyR-antibodies in thymoma patients is associated with a more severe disease and can be used as a prognostic marker.

Objectives Autonomic symptoms are present in early stages of Parkinson's disease (PD), but evidence on how they are influenced by dopaminergic treatment remains unclear. The aim of this study was to investigate the impact of dopaminergic treatment on autonomic symptoms in early PD in a population-based cohort. Methods A total of 171 drug-naive patients with PD were investigated at diagnosis and 12 months later. Orthostatic blood pressure was measured, and autonomic symptoms were assessed by a preliminary version of the Movement Disorders Society-sponsored new version of the Unified Parkinson's Disease Rating Scale (range 0–4). Results In the 82% using dopaminergic treatment after 1 year, constipation and orthostatic blood pressure drop increased. There was a tendency towards increased orthostatic dizziness and urinary dysfunction. Dysphagia scores were reduced, and this was associated with higher levodopa-equivalent daily dose. Conclusions Dopaminergic treatment during the first year after initiation seems to have only a minor impact on autonomic symptoms in early PD. It may increase constipation and orthostatic dizziness, while dysphagia can improve. Autonomic symptoms remained mild after 1 year of dopaminergic treatment.

Myasthenia gravis (MG) is an autoimmune disease. Patients without detectable antibodies against the nicotinic acetylcholine receptor or the muscle-specific tyrosine kinase are referred to as seronegative MG (SNMG). Because late-onset congenital myasthenic syndromes (CMSs) due to RAPSN or DOK7 mutations may be mistaken for SNMG, we investigated their frequency in a nationwide SNMG cohort.We performed sequencing of RAPSN and DOK7 in all Norwegian SNMG patients (n = 74) and 37 healthy controls, examining for the N88K and c.1124_1127dupTGCC mutations, respectively.We found 1 patient homozygous for N88K and 2 carriers of the N88K mutation. Sequencing of DOK7 revealed no mutations.This study confirms that rapsn CMS can be mistaken for SNMG. In addition, the frequency of rapsn CMS in our nationwide SNMG cohort was found to be low. SNMG patients with an atypical clinical presentation and pediatric cases should be tested for the N88K mutation before initiation of immunosuppressive drug treatment or thymectomy.

Objective To review a series of patients who underwent Gamma Knife surgery (GKS) to identify prognostic factors for local growth control and survival. Methods During the period 1996–2006, 77 patients (42 men and 35 women) with a total of 143 metastases underwent GKS. A solitary lesion was present in 40 patients (51.9%). Results Growth control was achieved in 114 of 128 (89.1%) tumors and 59 of 70 (84.3%) patients. The median survival was 7 months (range 0–73 months) after GKS and 67 months (range 4–327 months) from the time of diagnosis. Patients with absence of extracranial disease lived longer than patients with more widespread disease—median 16 months (range 3–52 months) versus 6 months (range 0–73 months; P = 0.014). A total tumor volume of less than 5 cc was associated with longer survival ( P = 0.041). Survival was significantly longer in recursive partitioning analysis (RPA) class 1 (22 months) than RPA class 2 (7 months) and RPA class 3 (3 months; P = 0.008). Even in cases of treatment failure with tumor growth or appearance of new metastases, GKS slowed down the cerebral disease with no significant reduction in the duration of survival. Conclusions GKS for melanoma brain metastasis provides a high rate of local tumor control. Survival is longest for well-functioning patients with absence of extracranial metastases or with an intracerebral total tumor volume less than 5 cc.

Background The aim of this study was to evaluate characteristics and long-term outcome of young patients with ischemic stroke (15-49 years at stroke onset) and aphasia. Methods Aphasia was defined as less than 10 points in the speech subscale of the Scandinavian Stroke Scale on long-term follow-up. Risk factors, origin, complications, social factors, and the Nottingham Health Profile subscores were compared between aphasic and nonaphasic young patients with ischemic stroke. On long-term follow-up, patients with aphasia were invited for further assessment of severity and subtype of aphasia. Results The study comprised 195 patients still alive after a mean follow-up of 6 years. Twenty (10.3%) patients had aphasia. Aphasia was associated with cardiac embolism ( P = .007), myocardial infarction ( P = .005), epilepsy ( P P = .021), and social isolation ( P = .054). On follow-up, 13 patients with aphasia underwent further assessment. These patients had all improved into milder aphasia subtypes. Conclusion Our study suggests that relatively few young patients with ischemic stroke have clinically significant aphasia on long-term follow-up. However, there are clinically significant differences between patients with and without aphasia that should be the focus of future research.

A right-handed woman of 90, taking aspirin 160 mg daily, suffered acute neck pain radiating to the shoulders, with right side hemiparesis and numbness occurring minutes thereafter. On admission 2.5 hrs later, examination showed paresis and hyporeflexia of the right limbs accompanied by neck stiffness and vertebral tenderness in level C7. Acute stroke was the initial working diagnosis. Cerebral CT was normal. Symptoms progressed with left arm numbness and left ancle clonus, and eight hours after symptom onset there was bilateral plantar inversion, reduced skin prick sensibility below C4, bladder paresis and anal sphincter hypotonia. CT myelography revealed an intraspinal mass extending from C2 to C6. 14 hours after symptom onset, a spinal epidural haematoma was removed by spinal laminectomy. Recovery and functional outcome was good. Symptoms, work-up and treatment are discussed with reference to previous publications.

Some myasthenia gravis (MG) patients have antibodies against skeletal muscle antigens in addition to the acetylcholine receptor (AChR). Two major antigens for non-AchR antibodies in MG are the Ca(2+) release channel of the sarcoplasmic reticulum, the ryanodine receptor (RyR) and titin, a gigantic filamentous muscle protein essential for muscle structure, function and development. RyR and titin antibodies are found mainly in thymoma MG patients and in a few late-onset MG patients and correlate with a severe MG disease. The presence of titin antibodies, which bind to key regions near the A/I junction and in the central I-band, correlates with myopathy. The immunosuppressant (FK506), which enhances Ca(2+) release from the RyR, seems to have a symptomatic effect on MG patients with RyR antibodies. The RyR antibodies recognize a region near the N-terminus important for channel regulation and inhibit Ca(2+) release in vitro. However, evidence that antibodies against the intracellular antigens RyR and titin are pathogenic in vivo is still missing.

Objectives To investigate the role of acetylcholine receptor (AChR) and other anti-muscle autoantibodies in myasthenia gravis (MG). Since many of these autoantibodies target proteins with structural or signalling functions, we examined the effect of MG sera on muscle cell morphology. Materials and methods Primary human myoblast cultures were exposed to MG sera and morphological changes observed by light and fluorescence microscopy. Results MG patient sera caused changes in cell shape (cell retraction) and led to the formation of inclusion bodies and intracellular vesicles. A disordered arrangement of actin microfilaments was also observed. The effects were not complement-mediated, were both dose- and time-dependent, and appeared to correlate with disease severity of the MG donor. Conclusion The factors responsible for these effects in vitro may also play a role in the pathogenesis of MG in vivo. Further study of these factors may improve our understanding of MG pathogenesis.

Myasthenia gravis (MG) is caused primarily by autoantibodies against the nicotinic acetylcholine receptor (AChR), but autoantibodies to other muscle proteins may be present. Many of these proteins have structural or signalling functions, the disruption of which may affect muscle cell morphology or viability. In order to investigate the role of such autoantibodies in MG, we examined the effect of MG patient sera, of different autoantibody composition and obtained at different stages of disease severity, on primary human muscle cells. Sera from MG patients induced changes in cell morphology from typical elongated cells to an irregular phenotype, caused the formation of inclusion bodies and intracellular vesicles, and led to a disordered arrangement of actin microfilaments. Sera from the most severely affected patients also induced cell death, which did not occur via classic apoptosis. The effects were not complement-mediated and were dose- and time-dependent. As the effects observed in the cell culture system correlated with disease severity, a greater understanding of the individual factors responsible for these effects may improve our understanding of MG pathogenesis and be of value in the assessment of disease in individual patients.

Patients with myasthenia gravis can have antibodies against skeletal muscle ryanodine receptor (Ry1), the sarcoplasmic reticulum calcium-release channel, which plays a crucial role in excitation-contraction coupling. We have screened a panel of overlapping Ry1 fusion proteins with Ry1 antibody-containing myasthenia gravis sera to identify the main immunogenic region. The pc2 Ry1 fusion protein representing a Ry1 region close to the N-terminus (residues 799-1172) was identified as the main immunogenic region for the antibodies. The binding kinetics of the Ry1 antibodies to the pc2 Ry1 fusion protein were tested using an optical biosensor. Ry1 antibodies in the IgG fraction from sera of patients with myasthenia gravis bound with high affinity and with a stoichiometry of 1:1. The functional effect of these Ry1 antibodies was tested in an in vitro Ca2+-release assay. The Ry1 antibodies induced a twofold increase of the half-maximal concentration for 4-Cl-m-cresol-induced Ca2+ release from terminal cisternae vesicles but had no effect on V(max). The effect on 4-Cl-m-cresol-induced Ca2+ release was specific, as preincubation of the active IgG fraction with the pc2 Ry1 fusion protein abolished the inhibition. These data suggest that the Ry1 sequence defined by residues 799-1172 is involved in the regulation of Ry1 function, and that this regulation could be functionally affected in vivo in patients with myasthenia gravis.

Similar to human autoimmune myasthenia gravis (MG), canine MG occurs spontaneously and is associated with autoantibodies against the nicotinic acetylcholine receptor (AChR). In addition to AChR, human MG patients with thymoma or late-onset MG have antibodies against titin and ryanodine receptor (RyR). The objective of this study was to establish if dogs with confirmed MG (AChR antibody titer >0.6 nmol/l) also developed titin and RyR antibodies and identify possible associations with thymoma, late age of onset, or severity of clinical signs. Sera from dogs (n=430) with previously diagnosed autoimmune MG (N=415), other immune-mediated neuromuscular disorders including polymyositis (PM) and masticatory muscle myositis (N=5), and control dogs (N=10) were evaluated for the presence of titin antibodies in ELISA using MGT-30 as antigen, a peptide representing the main immunogenic region (MIR) for human titin antibodies. Titin antibody positive sera were further examined for RyR antibodies in Western blots using a RyR fusion protein (pc2-RyR) as antigen, which covers the MIR for human MG sera. Titin antibodies were found in sera of 80/430 dogs. Thymoma was present in 11/80 and age of onset was after 4 years in 66/80 titin positive dogs. Two of the titin positive dogs had PM. RyR antibodies were found in 13/80 sera (8/13 thymoma, 12/13 age of onset after 4 years, and 1/13 PM). Neither titin nor RyR antibodies were found in sera of healthy control dogs. Acute fulminating MG was described in five dogs with both titin and RyR antibodies. From these studies we conclude that titin and RyR antibodies in canine and human MG have a similar association with thymoma, late-onset MG, and possibly with more severe forms of MG.

Background: Myasthenia gravis (MG) is caused by autoantibodies to the acetylcholine receptor (AChR). NonAChR muscle autoantibodies are present in many MG serum samples, mainly from patients with thymoma or lateonset MG. The exact relationship between MG severity and several non-AChR muscle antibodies is unknown. Objective: To study the correlation between the severity of MG and the concentration of antibodies against striated muscle tissue sections, titin, citric acid antigen, ryanodine receptor, and AChR. Setting: The severity of MG was graded in 146 consecutive patients with MG, and their serum samples were tested for the presence of autoantibodies. Ten patients who were titin antibody positive were observed in longitudinal follow-up. Results: No significant difference was found in MG severity between late-onset and thymoma MG. Titin, citric acid antigen, and ryanodine receptor antibodies occurred significantly more often among patients with severe MG than among patients with less severe disease. Changes in MG severity correlated with changes in titin antibody titer in the individual patient. Titin antibodies showed a better longitudinal correlation with disease severity than the AChR antibodies. Conclusions: Non-AChR muscle autoantibodies occurred more frequently in severe MG regardless of MG subgroup. Thymoma per se does not generate a more severe MG. It may well be the presence of a humoral immune response to non-AChR muscle antigens such as titin, citric acid antigen, and ryanodine receptor that leads to a severe disease, not the presence of thymoma or a late age of onset. These antibodies can serve as important prognostic markers in MG regardless of the presence of thymoma. Arch Neurol. 2000;57:1596-1600

Myasthenia gravis (MG) is caused by autoantibodies to the acetylcholine receptor (AChR), but several other muscle autoantibodies have also been identified in patient sera. We studied muscle autoantibodies against AChR, striated muscle tissue sections (SH), titin, citric acid antigen (CA), and ryanodine receptor (RyR) in sera from 146 consecutive MG patients to evaluate whether a single test or several tests together can predict a thymoma. The MG patients were divided into five subgroups; ocular MG, early-onset MG (< 50 years), late-onset MG (≥ 50 years), MG with thymoma, and AChR antibody negative MG. AChR, SH, titin, CA, and RyR antibodies were detected in 85%, 34%, 34%, 25%, and 14% of the MG patients, respectively. For thymoma MG, AChR, SH, titin, CA, and RyR antibodies were detected in 100%, 75%, 95%, 70%, and 70% respectively. SH, titin, CA, RyR antibodies, and computed tomography of the anterior mediastinum have similar sensitivity for thymoma MG. The specificity of RyR, titin, CA, and SH antibodies for thymoma was 70%, 39%, 38%, and 31%, respectively, which is significantly higher for RyR antibodies than for the others. No single muscle antibody assay can predict a thymoma, and a combination of several antibody assays is preferred, although RyR antibody testing alone showed 70% sensitivity and specificity for thymoma MG. SH and CA antibodies provided only little additional information.

We studied 65 patients with myasthenia gravis (MG). Clinical, neurophysiological, immunological, and histological findings suggested the coexistence of a presumed autoimmune myopathy. The clinical features were persistent pyridostigmine-resistant weakness and atrophy of striated muscles. The myopathy was found more often in patients with late-onset MG than in those with early-onset (37% vs 13%). Patients with myopathy were also prone to have other immune disorders (47% vs 13%). Elevated titres of antibodies against titin were detected more often in patients with electromyography (EMG) evidence of myopathy than in the sera of those without, and only in late-onset MG cases.

Background Tumor necrosis factor (TNF) α and TNF-β are proinflammatory cytokines thought to be involved in the pathogenesis of myasthenia gravis (MG). Objective To examine whether TNF polymorphisms are associated with MG, MG subgroups, and the presence of titin and ryanodine-receptor antibodies. Patients and Methods We did genotyping on 30 patients with MG and 92 healthy blood donors for 2 biallelic TNFA polymorphisms (G to A at positions −238 and −308) and 1 TNFB polymorphism ( Nco I digestive site) using methods based on the polymerase chain reaction. Results Patients with thymoma were typically homozygous for both the TNFA*T1 and the TNFB*2 alleles, but patients having an early onset of MG without thymoma were carriers of the TNFA*T2 and TNFB*1 alleles. Patients without thymoma who had the titin antibody had the same high frequency of TNFA*T1 and TNFB*2 as patients with thymoma, whereas patients without the titin antibody carried the same allele, TNFA*T2 and TNFB*1 , regardless of age and thymic disease. No association was found with acetylcholine-receptor levels or disease severity for any of the TNFA or TNFB polymorphisms. Conclusion Patients having MG, including those with thymoma, who have the titin antibody are most often homozygous for the TNFA*T1 and TNFB*2 alleles, whereas the presence of the TNFA*T2 and TNFB*1 alleles correlates with early-onset MG and the absence of titin antibodies.

More than 90% of myasthenia gravis (MG) patients with a thymoma have antibodies against titin. We have identified titin mRNA transcripts in thymomas by RT-PCR and Southern blotting. The transcripts cover the main immunogenic region (MIR) and a central I-band epitope reactive with some MG patients' antibodies. The presence of the central I-band epitope was confirmed by immunohistochemistry as a titin antibody reactive with this part of titin, stained thymoma epithelial cells and a thymoma extract in Western blots. Our findings suggest that the initiation of paraneoplastic titin reactivity is correlated with the expression of titin sequences within the thymoma.

Fluctuating or episodic weakness starting in infancy is seen in congenital myasthenic syndromes (CMSs), periodic paralyses, and a disorder precipitated by febrile illness mapped to Xp22.3.1 Mutations in rapsyn ( RAPSN ) cause congenital myasthenia and more than 20 mutations with three different clinical phenotypes have been identified.2-4 The patient, now 19 years old, developed cyanotic spells at age 3 days. He was hypotonic with a weak cry, but had no persisting respiratory difficulties. He received nasogastric feeding and antibiotics, despite normal infection parameters, and was discharged well after 3 days. At age 6 months, fever developed again, possibly due to a respiratory infection; he also had problems swallowing saliva and one episode in which he became cyanotic and increasingly hypotonic. His leukocyte count fell from 36.8 to 9.2 (normal 3.5 to 11.0 × 109/L); chest x-ray, cerebral ultrasound, and EEG were normal. He was treated with oxygen and ephedrine and discharged well 5 days later. During the next 5 years, he had five more attacks, all preceded by fever and characterized by generalized weakness, including facial and tongue muscles, ptosis, and diplopia. He became briefly respirator dependent on …

Myasthenia gravis (MG) is caused by antibodies against the acetylcholine receptor (AChR). However, some MG patients have antibodies against non-AChR epitopes of skeletal muscle including titin. In this study, we tested peripheral blood lymphocytes from 11 MG patients and 13 blood donors in a lymphocyte transformation test using the antigen MGT-30, a titin epitope that represents the main immunogenic region. Stimulation index (SI) was defined as counts per minute (cpm) in stimulated culture minus background divided by cpm in unstimulated culture minus background. MGT-30 caused a significant stimulation of T-cells from titin-antibody positive MG patients; SI=1.84±0.77, compared with titin-antibody negative patients; SI=0.67±0.28 (p=0.01), and blood-donors; SI=0.65±0.21 (p=0.0005). SI after PHA stimulation was similar in MG patients with and without titin-antibodies and blood-donors. After MGT-30 stimulation, IL-4 concentrations in the supernatant were 84–150pg/mL in all 4 titin-positive patients examined. IL-4 levels were below the detection limit for the ELISA used (60pm/ml) in the cultures from the 8 blood-donors and the 1 titin-negative MG patient that were tested. Thus, MG patients with anti-titin antibodies also have a T-cell mediated immune reactivity against titin.

Paraneoplastic MG is probably caused by sensitisation of T-cells to muscle-like epitopes presented on the neoplastic epithelial cells. Accessory molecules on antigen-presenting cells and T-cells are important for the outcome of the immunisation process. In this study, cryostat sections from 13 thymomas (11 with MG, 2 without; 10 non-invasive, 3 invasive; 3 spindle-cell, 10 polygonal-cell thymomas) and 6 normal thymuses from children were examined for the accessory molecules ICAM-1, VCAM-1, LFA-3 and CD28 using commercially available mouse monoclonal antibodies and immunoperoxidase staining.

We have tested sera from 21 thymectomized patients with onset of MG after 40 years of age and without thymoma for antibodies against titin, using ELISA with the titin peptide MGT-30. Titin is a myofibrillar protein unique to striated muscle and important for the elastic recoil of muscle cells. Titin antibodies were detected in 9 of the 21 sera. MG symptoms as assessed by a 6 point disability score (0–5) were significantly more severe in the titin antibody positive patients both at peak of illness; 3.7 vs. 3.1 (p < 0.02) and at latest follow up; 2.1 vs. 0.8 (p < 0.01). All titin antibody positive patients were on immunosuppressive drug treatment at least follow-up, whereas only 3 of 12 patients without titin antibodies used immunosuppressive drugs. The presence of circulating titin antibodies in late-onset non-thymoma MG patients indicates a more severe disease.

Myasthenia gravis is an autoimmune disease caused, in most cases, by antibodies attaching to the acetylcholine receptor. Some myasthenia gravis patients have antibodies that bind in a cross-striational pattern to skeletal and heart muscle tissue sections (striational antibodies). These antibodies react with epitopes on the muscle proteins titin and ryanodine receptor, are found mainly in sera of patients with thymoma and late-onset myasthenia gravis, and may correlate with myasthenia gravis severity. Their presence may predict an unsatisfactory outcome after thymectomy. The detection of titin and ryanodine receptor antibodies provides more specific clinical information than the immunofluorescent demonstration of striational antibodies.