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Biomedical subjects

J A Aarli

Publications and source records attributed to J A Aarli.

At least 19 recordsLinked to original sources

Ryanodine receptor autoantibodies in myasthenia gravis patients with a thymoma.

Sera from patients with myasthenia gravis were examined by Western blot for the presence of antibodies to proteins of the sarcoplasmic reticulum from rabbit skeletal muscle. Fourteen of 30 patients with myasthenia gravis and a thymoma had IgG autoantibodies to the calcium release channel of the sarcoplasmic reticulum (the ryanodine receptor), which plays a crucial role in the mechanism of excitation-contraction coupling in striated muscle. Ryanodine receptor autoantibodies were not detected in any of the 45 sera from patients with myasthenia gravis without a thymoma. Ryanodine receptor autoantibodies may have pathogenetic relevance in thymoma-associated myasthenia gravis.

Autoantibodies

Myasthenia gravis patients with a thymoma have antibodies against a high molecular weight protein in sarcoplasmic reticulum.

Our purpose was to investigate whether components of the sarcoplasmic reticulum (SR) are relevant antigens in myasthenia gravis (MG). Using enzyme-linked immunosorbent assay (ELISA), 75 MG sera and 120 control sera were examined for IgG antibodies against SR prepared from rabbit skeletal muscle. 16/30 thymoma MG patients had IgG antibodies that reacted with SR. 1/30 MG patients with thymic hyperplasia and 3/15 MG patients with thymic atrophy had SR antibodies in low concentrations. Control sera were negative. Using immunoblot, SR antibodies were detected in the thymoma group only. 14/30 sera from thymoma patients reacted with a protein of 320 kDa relative molecular weight. The only reported SR protein with similar electrophoretic mobility is the subunit of the spanning protein which links junctional SR to sarcolemma and functions as a calcium-release channel.

Adult

Early prognostic factors for disability in multiple sclerosis, a European multicenter study.

The effects of initial clinical variables on short-term prognosis are analyzed in a cross-sectional study of 574 multiple sclerosis patients from 7 centers in 5 European countries. Patients with a primary progressive course had a 2.3 higher mean disability score (EDSS) than the primary remittent group after a mean duration of disease of 6.6 years. High age at onset was associated with a primary progressive course, and was also related to increased risk of a rapid shift to a secondary progressive course. Among the remittent patients without a secondary progressive course a high age at onset was significantly correlated to a higher disability score. In the whole remittent group the presence of pyramidal and cerebellar symptoms at onset predicted both a high disability score and a rapid shift to a secondary progression, while the effect was reverse for sensory and visual symptoms. No difference between the sexes was found.

Adult

Myasthenia gravis muscle antibodies examined by ELISA: IgG and IgM antibodies characterize different patient subgroups.

Sera from 90 myasthenia gravis (MG) patients were examined for antibodies against skeletal muscle citric acid extract (CA) antigens by ELISA and indirect haemagglutination (IHA). 31% (ELISA) and 24% (IHA) of the sera were positive, and the results of the two tests were in good agreement. 18 of 28 patients positive in ELISA had IgG CA-antibodies, 10 had IgM and 3 IgA CA-antibodies. The patients with IgG antibodies had a high mean age of MG disease onset, and 9/14 thymectomized patients had a thymoma. Patients with IgM CA-antibodies had a much lower age of onset and 4/5 thymectomized patients had thymus hyperplasia. IgM antibody positive patients had a long disease duration, indicating that they produce IgM antibodies for an indefinite period of time without switching to IgG antibody production.

Adolescent

Myasthenia gravis with thymoma is not associated with an increased incidence of non-muscle autoimmune disorders.

Three groups of thymectomized patients with myasthenia gravis (MG) were selected for study, 16 with thymoma, 16 with thymic atrophy and 32 with follicular hyperplasia of the thymus. All 16 patients with thymoma, 15/16 with thymus atrophy and 30/32 with follicular hyperplasia had AChR antibodies. Non-receptor muscle (CA) antibodies were found in sera of 15/16 patients with thymoma, 3/16 with thymus atrophy and in none of the sera from patients with follicular hyperplasia. There were 2 patients with thymoma and polymyositis, but none of the thymoma patients had rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) or other autoimmune disorders. Among the 32 patients with follicular hyperplasia of the thymus were 2 with SLE, 2 with RA and 1 with juvenile diabetes mellitus. In this study, there was an increased incidence of non-muscle autoimmune disorders among MG patients with follicular hyperplasia of the thymus but not among MG patients with thymoma.

Adult

Non-receptor muscle antibodies in myasthenia gravis are of IgG1 and IgG4 subclasses.

The IgG subclass distribution of non-receptor muscle antibodies was examined in 15 myasthenia gravis (MG) sera, employing an indirect haemagglutination-immunofluorescence technique. Four sera contained only IgG1, 4 contained only IgG4 and 7 contained both IgG1 and IgG4 muscle antibodies. IgG2 and IgG3 antibodies were not found. Among 11 patients with a defined thymus pathology 8 had thymoma and 3 had thymic atrophy, but there was no correlation between antibody subclass pattern and thymic pathology. Patients with both IgG1 and IgG4 antibodies tended to have the longest disease duration. We conclude that IgG non-receptor muscle antibodies in MG are of the IgG1 and/or IgG4 subclasses, irrespective of thymic pathology.

Adult

Activation of blood platelets in workers exposed to organic solvents.

Organic solvents probably exert their clinical effects through distortion of cellular membrane structure and function. Blood platelets represent an easily available membrane system. This study describes an evaluation of mean platelet volume (MPV) and total platelet count (TPC) in a group of workers exposed to a mixture of organic solvents in paint factories. We have found a correlation between decreased MPV and present exposure. The reduction was reversed within an exposure-free interval of 3 weeks. The intracellular adenosine triphosphate/adenosine diphosphate (ATP/ADP) ratio was significantly increased in exposed workers, compatible with dense granule secretion. A quantitative study of the phosphoinositide cycle in the platelets revealed an increased concentration of the phosphatidic acid, indicating an increased turnover. These findings are consistent with a solvent-induced activation of circulating platelets.

Adenosine Diphosphate

Antibodies in sera from patients with inflammatory demyelinating polyradiculoneuropathy react with ganglioside LM1 and sulphatide of peripheral nerve myelin.

Sera from 23 patients with acute Guillain Barré syndrome (GBS), 15 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and from 40 age-matched blood donors were analysed for antibodies to acidic glycosphingolipids from human brain and peripheral nerve. Antibodies to ganglioside LM1, the major ganglioside of peripheral nerve myelin. were found in 43% of GBS and in 67% of CIDP patients' sera, and in 20% of the blood donors. However, antisulphatide antibodies were detected in 65% and 87% of the sera from GBS and CIDP patients, respectively, but only in 15% of the control sera. Sulphatide is the major acidic glycosphingolipid in myelin and its concentration in peripheral nerve myelin is 100 times higher than that of LM1. The high frequency of LM1 and, in particular of sulphatide antibodies, might thus be relevant to the pathogenesis of the GBS and CIDP.

Adolescent

Electroencephalography, evoked potentials and MRI brain scans in saturation divers. An epidemiological study.

One hundred and fifty-six air and saturation divers, mean age 33.6 (range 21-49) years, were examined. The control group consisted of 100 offshore workers and policemen with the health requirements to have a diving certificate, mean age 34.0 (range 22-48) years. The examination protocol included electroencephalography (EEG), visual evoked potentials (VEPs), brain-stem auditory evoked potentials (BAEPs) and magnetic resonance imaging (MRI) of the brain and brain-stem. Abnormal EEGs, with focal slow waves mostly in the temporal regions and sharp potentials, were found in 18% of the divers and in 5% of the controls (P = 0.003). Abnormal EEGs correlated significantly with the exposure to saturation diving (P = 0.0006) and the prevalence of decompression sickness (P = 0.0102). Alcohol consumption was negatively correlated with abnormal EEGs (P = 0.0006). Mean I-III BAEP latency was increased (P = 0.047) in the diver group. P100 VEP latency decreased with age (21-49 years). High signal intensity changes obtained by MRI were found in 33% of the divers and in 43% of the controls (P = 0.14). It is concluded that the nervous system of saturation divers is influenced by their occupation and that EEG is a useful method in the health examination of divers.

Adult

Myasthenia gravis patients with thymus hyperplasia and myasthenia gravis patients with thymoma display different HLA associations.

Thirty myasthenia gravis (MG) patients (9 with thymoma, 12 with thymus hyperplasia and 9 with thymic atrophy) and 181 Norwegian healthy controls were serologically typed for HLA-A, -B and -DR antigens and genomically typed for HLA-DQA1 and HLA-DQB1 alleles by probing in vitro amplified DNA with sequence-specific oligonucleotides. In patients with thymus hyperplasia the frequency of the DQB1*0201 allele was increased compared to controls (RR = 3.5, p less than 0.05), whereas among the patients with thymoma this allele was not observed (RR = 0.06, p less than 0.01). The frequencies of HLA-B8, -DR3 and -DQA1*0501, which are in strong linkage disequilibrium with DQB1*0201, were increased in patients with hyperplasia and reduced in patients with thymoma. The data suggest that different HLA genes predispose to two different forms of MG.

Alleles

Epidemiology of amyotrophic lateral sclerosis in Hordaland county, western Norway.

The incidence, prevalence and prognosis of amyotrophic lateral sclerosis (ALS) in the county of Hordaland, western Norway were determined for the years 1978 through 1988. The average annual incidence rate was 1.60 per 100,000 population with a male to female ratio of 1.26 (95% confidence interval: 0.76-2.09). The maximal age-specific annual incidence was 8.12 per 100,000 and occurred in the age-group between 61 and 65 years. The prevalence of ALS was 3.67 per 100,000 on December 31, 1988. The average age at the onset of the disease was 60.9 years ranging from 34 to 82 years of age. Survival was studied with life table techniques. Median survival from the onset of symptoms was 28.0 months overall. In patients with bulbar onset the median survival was 24.0 months whereas it was 40 months in patients with spinal onset of disease (log rank test, P = 0.0004). The difference in survival between ALS with bulbar or spinal onset was not explained by age or sex differences in the two groups.

Aged

Neurological long term consequences of deep diving.

Forty commercial saturation divers, mean age 34.9 (range 24-49) years, were examined one to seven years after their last deep dive (190-500 metres of seawater). Four had by then lost their divers' licence because of neurological problems. Twenty seven (68%) had been selected by neurological examination and electroencephalography before the deep dives. The control group consisted of 100 men, mean age 34.0 (range 22-48) years. The divers reported significantly more symptoms from the nervous system. Concentration difficulties and paraesthesia in feet and hands were common. They had more abnormal neurological findings by neurological examination compatible with dysfunction in the lumbar spinal cord or roots. They also had a larger proportion of abnormal electroencephalograms than the controls. The neurological symptoms and findings were highly significantly correlated with exposure to deep diving (depth included), but even more significantly correlated to air and saturation diving and prevalence of decompression sickness. Visual evoked potentials, brainstem auditory evoked potentials, and magnetic resonance imaging of the brain did not show more abnormal findings in the divers. Four (10%) divers had had episodes of cerebral dysfunction during or after the dives; two had had seizures, one had had transitory cerebral ischaemia and one had had transitory global amnesia. It is concluded that deep diving may have a long term effect on the nervous system of the divers.

Adult

Incidence of multiple sclerosis in Hordaland, western Norway: a fluctuating pattern.

The incidence of multiple sclerosis (MS) was studied in the county of Hordaland, western Norway. A significant increase in incidence in the period 1958-1987, a decline followed by a gradual increase in mean age at onset, geographic differences in time trends and a biphasic pattern revealed by a birth cohort analysis support the theory of real time-space fluctuations in the incidence of MS over time.

Adult

Heart muscle antibodies in myasthenia gravis.

Myasthenia gravis (MG) may in some patients, especially in those with a thymoma, involve the heart. Using an ELISA, we measured heart muscle antibodies in sera from 75 MG patients and in 173 control sera. Heart muscle antibodies were detected in 29/30 thymoma MG patients, in none of 30 young onset MG patients with thymic hyperplasia and in 7/15 late onset MG patients with thymic atrophy. Among the controls, four sera had a very low concentration of heart muscle antibodies. Absorption studies showed that the heart muscle antibodies cross-react with skeletal muscle, but are unrelated to acetylcholine receptor antibodies.

Adolescent

[Mental retardation and epilepsy].

504 clients, all living in institutions for mentally retarded, were examined with regard to level of functioning. 123 clients had epilepsy and 381 did not. The epileptic patients had more motor and communication disturbances and needed more help with everyday activities. Epilepsy was important, but explained fewer of the observed differences than did the degree of the motility problems. Among the clients with epilepsy the frequency of seizure was important. More frequent seizure was associated with lower levels of achievement. Therefore mentally retarded persons with epilepsy should be thoroughly examined/optimally treated by a neurologist/paediatrician and assured a medical follow up prior to possible transfer to a lower level of care.

Adolescent