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Biomedical subjects

B G van Engelen

Publications and source records attributed to B G van Engelen.

At least 55 records · Page 3Linked to original sources
PubMed1998

Acceleration in the rate of CNS remyelination in lysolecithin-induced demyelination.

One important therapeutic goal during CNS injury from trauma or demyelinating diseases such as multiple sclerosis is to develop methods to promote remyelination. We tested the hypothesis that spontaneous remyelination in the toxic nonimmune model of lysolecithin-induced demyelination can be enhanced by manipulating the inflammatory response. In PBS-treated SJL/J mice, the number of remyelinating axons per square millimeter of lesion area increased significantly 3 and 5 weeks after lysolecithin injection in the spinal cord. However, methylprednisolone or a monoclonal antibody (mAb), SCH94.03, developed for its ability to promote remyelination in the Theiler's virus murine model of demyelination, further increased the number of remyelinating axons per lesion area at 3 weeks by a factor of 2.6 and 1.9, respectively, but did not increase the ratio of myelin sheath thickness to axon diameter or the number of cells incorporating tritiated thymidine in the lesion. After 3 weeks, the number of remyelinating axons in the methylprednisolone or mAb SCH94.03 treatment groups was similar to the spontaneous remyelination in the 5 week PBS control-treated group, indicating that these treatments promoted remyelination by increasing its rate rather than its extent. To address a mechanism for promoting remyelination, through an effect on scavenger function, we assessed morphometrically the number of macrophages in lesions after methylprednisolone and mAb SCH94.03 treatment. Methylprednisolone reduced the number of macrophages, but SCH94.03 did not, although both enhanced remyelination. This study supports the hypothesis that even in toxic nonprimary immune demyelination, manipulating the inflammatory response is a benefit in myelin repair.

Animals↗
PubMed1998

Frequent occurrence of anti-tRNA(His) autoantibodies that recognize a conformational epitope in sera of patients with myositis.

OBJECTIVE: To investigate the incidence of autoantibodies directed to deproteinized transfer RNA(His) (tRNA(His)) in anti-Jo-1 positive myositis patients and to determine the major B cell epitope. METHODS: One hundred sixty-seven myositis sera were screened by immunoblotting and enzyme-linked immunosorbent assay for the presence of anti-Jo-1 antibody. Autoantibodies directed to deproteinized RNA were detected by immunoprecipitation. Ribonuclease cleavage experiments were performed to determine the tRNA(His)-specific features important for recognition. RESULTS: Approximately one-third of the anti-Jo-1 positive sera also contained autoantibodies recognizing tRNA(His). This recognition was independent of modified bases, but the presence of stabilizing Mg2+ ions appeared to be essential for efficient immunoprecipitation. Transfer RNA(His)-specific features in the anticodon loop were not protected from ribonuclease cleavage by bound antibodies, while protection of bases located in the D and T loops was observed. CONCLUSION: A significant number of anti-Jo-1 positive myositis sera contain anti-tRNA(His) activity. Formation of the major autoepitope on tRNA(His) is strongly dependent on proper folding of this molecule mediated by an interaction between D and T loops which is stabilized by either modified residues or Mg2+ ions.

Autoantibodies↗
PubMed1998

Genetic characteristics of myoadenylate deaminase deficiency.

Two types of myoadenylate deaminase (MAD) deficiency have been described, primary or inherited, and secondary or acquired MAD deficiency. In this study, we investigated whether secondary MAD deficiency is indeed acquired or merely coincidental. We demonstrated the same underlying molecular defect, a C34T transition, in both types of deficiency. Furthermore, the same frequency of the mutant MAD allele was found in the general population as in patients with neuromuscular complaints. We therefore conclude that in the Dutch population, secondary MAD deficiency is merely a "coincidental" finding, and that MAD deficiency is a harmless genetic variant.

AMP Deaminase↗
PubMed1998

A double missense mutation in the ATM gene of a Dutch family with ataxia telangiectasia.

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by cerebellar ataxia, telangiectasia, immunodeficiency, elevated alpha-fetoprotein levels, chromosomal instability, predisposition to cancer, and radiation sensitivity. We report the identification of a new, double missense mutation in the ataxia telangiectasia gene (ATM) of a Dutch family. This homozygous mutation consists of two consecutive base substitutions in exon 55: a T-->G transversion at position 7875 of the ATM cDNA and a G-->C transversion at position 7876. These transversions were confirmed by polymerase chain reaction/primer-induced restriction analysis with CelII. The double base substitution results in an amino acid change of an aspartic acid to a glutamic acid at codon 2625 and of an alanine to a proline at codon 2626 of the ATM protein. Both amino acids are conserved between the ATM protein and its functional homolog, the Atm gene product in the mouse. Furthermore, the Chou-Fasman and Robson predictions both demonstrate a change in the secondary structure of the ATM protein carrying the D2625E/A2626P mutation. These findings suggest that the double base substitution in the ATM gene is a disease-causing mutation.

Adolescent↗
PubMed1998

Intravenous immunoglobulin preparation increases myoplasmic calcium concentration by activating the dihydropyridine-ryanodine receptor complex.

A human intravenous immunoglobulin preparation (IVIg) released Ca2+ from the sarcoplasmic reticulum of cultured human skeletal muscle cells in a dose-dependent manner. Blocking the dihydropyridine-ryanodine receptor complex abrogated the IVIg-mediated Ca2+ response, whereas inhibition of the voltage-operated Na+-channels or acetylcholine receptors did not. This effect of IVIg was not mediated by its main component, the IgG molecules, and differed between preparations from different manufacturers. Heating destroyed the activity. Data shows that an unidentified serum protein present in IVIg can influence human muscle cells by an effect on the dihydropyridine receptor. This phenomenon may be important in interpreting the (side) effects of IVIg in neuromuscular diseases.

Calcium↗
PubMed1998

Hereditary neuropathy with liability to pressure palsies. Phenotypic differences between patients with the common deletion and a PMP22 frame shift mutation.

In six families with hereditary neuropathy with liability to pressure palsies (HNPP) the 17p11.2 deletion was absent, but single strand conformation-analysis and subsequent sequencing demonstrated a heterozygous G-insertion in a stretch of six Gs at nt 276281 of the PMP22 gene, resulting in a frame shift after Gly94. Haplotype comparison of the six families revealed common ancestry. We compared the phenotype of 23 patients from these six families with the phenotype of 63 patients of 17 families with the common deletion. The patients with the G-insertion showed the clinical, electrophysiological and morphological characteristics of common HNPP, but in addition they had significantly more neuropathic features, mimicking hereditary motor and sensory neuropathy type I (HMSN I) or Charcot-Marie-Tooth disease type 1 (CMT1). To explain this distinct phenotype we suggest that, by translation of the mutated gene, a markedly changed polypeptide is formed without the normal cytoplasmic C-terminal of the native protein, resulting in a loss of function similar to that with the common deletion, but exerting an extra disturbance of Schwann cell functions, probably by hampering normal myelin formation or maintenance.

Adolescent↗
PubMed1997

Lumbosacral plexus neuropathy: a case report and review of the literature.

Lumbosacral plexus neuropathy (LSPN) is an idiopathic clinical syndrome characterized by the sudden onset of neuropathic pain, followed by weakness and sometimes sensory disturbances in the distribution of the lumbosacral plexus. Prognosis is usually favourable, although complete recovery may take several months to years. LSPN is the lumbosacral counterpart of the neuralgic amyotrophy syndrome (idiopathic brachial plexus neuropathy). We present a patient who initially was misdiagnosed with a radicular syndrome, but illustrates the typical signs and symptoms of LSPN. We also give clinical and electromyographical criteria for the diagnosis of LSPN and review the literature.

Adolescent↗
PubMed1997

Differences between hereditary motor and sensory neuropathy type 2 and chronic idiopathic axonal neuropathy. A clinical and electrophysiological study.

To evaluate whether chronic idiopathic axonal polyneuropathy (CIAP) should be considered as hereditary motor and sensory neuropathy type 2 (HMSN type 2), we compared the clinical features of 48 patients with CIAP with those of 47 patients with HMSN type 2. In addition, we studied electrophysiological data in 20 patients with CIAP and in 20 patients with HMSN type 2. We found, in patients with HMSN type 2, that the initial symptoms were predominantly motor and that weakness and handicap were more severe and skeletal deformities more frequent, compared with those of CIAP patients. Electrophysiologically, the tibialis anterior muscle showed more denervation in patients with HMSN type 2, consistent with the predominance of motor symptoms. There was no important effect of age of onset on clinical features in HMSN type 2 patients. We conclude that in an individual patient with a sensory or sensorimotor idiopathic axonal polyneuropathy and no family history of polyneuropathies, the diagnosis HMSN type 2 is unlikely. However, if motor symptoms predominate, the diagnosis of HMSN type 2 should be considered.

Adult↗
PubMed1997

Enhancement of central nervous system remyelination in immune and non-immune experimental models of demyelination.

Studies in both humans and experimental animals indicate that there is potential for full remyelination following CNS demyelination, but the factors that control the degree of myelin repair are unknown. In the Theiler's virus model of demyelination CNS remyelination can be promoted either by global immunosuppression or by selective immunoglobulin therapy. In this paper we discuss whether immunoglobulin-mediated remyelination is a characteristic of immune-mediated demyelination, or whether immunoglobulin-mediated remyelination also occurs in the toxic-traumatic model of lysolecithin-induced demyelination. Our data support the hypothesis that even in a non-primary immune model of demyelination, manipulating the immune system can be beneficial in myelin repair.

Animals↗
PubMed1996

Can human polyclonal immunoglobulin raise the threshold for convulsions in rats?

In the present preliminary study we explored the possibility of an anticonvulsant effect of normal human immunoglobulin in an animal epilepsy model based on direct cortical stimulation in freely moving rats. After human immunoglobulin administration a significant and prolonged elevation of the threshold for convulsions was measured in 12% (6/49) of the total group of outbred Wistar rats. In the subgroup of more than seven months old Wistar rats this was 67% (6/9). When a threshold increasing effect of immunoglobulin occurred, it was detectable within 0.5-1 hour after administration, reached its maximum after approximately two hours and continued for at least 40 hours.

Animals↗
PubMed1996

Two divergent types of nerve pathology in patients with different P0 mutations in Charcot-Marie-Tooth disease.

In seven unrelated patients with a demyelinating motor and sensory neuropathy, we found mutations in exons 2 and 3 of the P0 gene. Morphologic examination of sural nerve biopsy specimens showed a demyelinating process with onion bulb formation in all cases. In four patients, ultrastructural examination demonstrated uncompacted myelin in 23 to 68% of the myelinated fibers, which is in agreement with the widely accepted function of P0 as a homophilic adhesion molecule. Three patients showed normal compact myelin, but morphology was dominated by the abundant occurrence of focally folded myelin. The two divergent pathologic phenotypes exemplify that some mutations act differently on P0 protein formation or function than others, which is probably determined by site and nature of the mutation in the P0 gene.

Adolescent↗
PubMed1995

Leukoencephalopathy with swelling in children and adolescents: MRI patterns and differential diagnosis.

In children, several neurological disorders are characterised by spongiform leukoencephalopathy. MRI of the brain typically shows white matter swelling, but does not enable differentiation of the various underlying disorders. The aim of this article is optimisation of the diagnostic value of MRI in leukoencephalopathy accompanied by swelling. MRI-based inclusion criteria were met by 20 patients in our database. The images were analysed using a detailed scoring list. In 13 of the 20 patients the clinical diagnosis was known (11 definite and 2 probable diagnoses). Characteristic MRI abnormalities could be defined in these patients. Of the 7 patients without a diagnosis, 5 had identical MRI abnormalities: diffuse hemisphere swelling and typical cysts in frontoparietal subcortical white matter and the tips of the temporal lobes. The clinical picture was also similar in these patients, suggesting a similar disease.

Adolescent↗
PubMed1995

White matter abnormalities in congenital muscular dystrophy.

Central nervous system (CNS) characteristics were examined in seventeen patients with autosomal recessive classic or "pure" congenital muscular dystrophy (CMD). In three patients, neuroradiological examination (CT/MRI) indicated hypodense white matter areas. Two out of these three patients had epilepsy (seizures and epileptic discharges on their EEG). Only two of the remaining patients had epileptic EEG discharges, but without clinical seizures. By comparing our results to data in the literature, we could conclude that the classic or "pure" form of CMD can be subdivided into two subtypes, i.e. those with and those without white matter hypodensities. A mild form of epilepsy or an epileptic predisposition on EEG can be part of the subtype with white matter hypodensities.

Adolescent↗
PubMed1995

Ocular and systemic manifestations of cerebrotendinous xanthomatosis.

PURPOSE: Cerebrotendinous xanthomatosis is a storage disease that usually leads to severe mental and neurologic deterioration before the diagnosis and start of treatment are established. We identified major ocular and systemic characteristics that may enable a diagnosis to be made earlier. METHODS: Ten patients (group 1) of the University Hospital Nijmegen, with a diagnosis of cerebrotendinous xanthomatosis, were re-examined for detailed ocular and major clinical manifestations. Meanwhile, we looked for similar but undiagnosed cases in patients (group 2) who visited the Institute of Ophthalmology during a 12-month period. RESULTS: A diagnosis of cerebrotendinous xanthomatosis had been made in the patients of group 1 at an average age of 40 years (range, 33 to 48 years). Subsequently, six new cases (group 2) were diagnosed in patients 7 to 37 years old (average age, 18 years). Bilateral cataract was the major ocular manifestation in all 16 patients. Small irregular corticonuclear opacities, anterior polar cataracts, and dense posterior subcapsular cataracts were diagnosed at various ages (mean, 18 years; range, 4 to 40 years). Four patients showed clinical signs of optic neuropathy, whereas retinal function was normal in all patients. Other major clinical signs included a history of chronic diarrhea (since childhood), mental deterioration (mean age, 23 years), neurologic deterioration (mean age, 31 years), and tendon xanthomas (mean age, 37 years). CONCLUSIONS: Appropriate biochemical investigations for cerebrotendinous xanthomatosis should be performed in patients with unexplained juvenile or early-onset adult cataracts, especially if these cataracts are associated with chronic diarrhea since infancy, mental retardation or deterioration, neurologic dysfunction, or xanthomas.

Adolescent↗
PubMed1995

A dysbalanced immune system in cryptogenic Lennox-Gastaut syndrome.

In children with cryptogenic Lennox-Gastaut syndrome we found a functionally impaired humoral immune response to a primary antigen (haemocyanin), despite signs of a triggered immune system consisting of elevated IgG concentrations. This combination of immunological findings, considered to be the expression of a dysbalanced-triggered as well as functionally impaired-immune system, has also been described in an auto-immune disease like systemic lupus erythaematodes in humans, and in genetically epilepsy-prone rats. The interactions between the immune system and the nervous system in Lennox-Gastaut syndrome will be discussed.

Adolescent↗
PubMed1995

Cerebrospinal neuron-specific enolase, S-100 and myelin basic protein in neurological disorders.

In this study levels of neuron-specific enolase (NSE), S-100 protein (S-100) and myelin basic protein (MBP) in cerebrospinal fluid (CSF) of children and adults with distinct neurological disorders were examined. A previous study from our department demonstrated age related reference values for these brain-specific proteins in CSF. The median concentration level of the 3 proteins in 17 different neurological disease groups versus the reference group was compared. Significantly higher MBP values were observed in patients with multiple sclerosis (MS), cerebrovascular accident (CVA), metabolic disorder and infection. Furthermore, significantly higher values were demonstrated for S-100 in CVA and for NSE in metabolic diseases. In CVA, the NSE and S-100 values were significantly related with MBP values, whereas in MS the NSE and S-100 were not related with MBP values.

Adult↗