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Inauguratie van prof. dr. Marc H.V. De Baets, benoemd in Faculty of Health, Medicine en Life Sciences tot hoogleraar Chronische inflammatie bij neurodegeneratieve aandoeninge

DGAT1 overexpression in muscle by in vivo DNA electroporation increases intramyocellular lipid content.

In adipose tissue, the microsomal enzyme 1,2-acyl CoA:diacylglyceroltransferase-1 (DGAT1) plays an important role in triglyceride storage. Because DGAT1 is expressed in skeletal muscle as well, we aimed to directly test the effect of DGAT1 on muscular triglyceride storage by overexpressing DGAT1 using in vivo DNA electroporation. A pcDNA3.1-DGAT1 construct in saline was injected in the left tibialis anterior muscle of rats, followed by the application of eight transcutaneous pulses, using the contralateral leg as sham-electroporated control. Electroporation of the DGAT1 construct led to significant overexpression of the DGAT1 protein. The functionality of DGAT1 overexpression is underscored by the pronounced diet-responsive increase in intramyocellular lipid (IMCL) storage. In chow-fed rats, DGAT1-positive myocytes showed significantly higher IMCL content compared with the control leg, which was almost devoid of IMCL (1.99 +/- 1.13% vs. 0.017 +/- 0.014% of total area fraction; P <0.05). High-fat feeding increased IMCL levels in both DGAT1-positive and control myocytes, resulting in very high IMCL levels in DGAT1-overexpressing myocytes (4.96 +/- 1.47% vs. 0.80 +/- 0.14%; P <0.05). Our findings indicate that DGAT1 contributes to the storage of IMCL and that in vivo DNA electroporation is a promising tool to examine the functional consequences of altered gene expression in mature skeletal muscle

Dysfunction at the motor end-plate and axon membrane in Guillain-Barre syndrome: a single-fiber EMG study

Dysfunction at the motor end-plate and axon membrane in Guillain-Barre syndrome: a single-fiber EMG study. Spaans F, Vredeveld JW, Morre HH, Jacobs BC, De Baets MH. Department of Clinical Neurophysiology, University Hospital, Postbox 5800, 6202 AZ Maastricht, The Netherlands. [email protected] In nine patients with Guillain-Barre syndrome (GBS), stimulation single-fiber electromyography (SFEMG) and serological studies were performed in the acute stage of the illness. Increased jitter and intermittent blocking of muscle fiber action potentials occurred to a varying degree in all patients. Five patients had elevated titers of antiganglioside antibodies. The most remarkable EMG phenomenon was the occurrence in all patients of impulse blocking at normal or slightly increased jitter. The assumption that this phenomenon was due to an axolemmal dysfunction was confirmed by the occurrence in two patients of concomitant blocking of two muscle fiber action potentials at strictly normal jitter values. In one patient this sign of axonal dysfunction was demonstrated with SFEMG at voluntary activation. In another patient, concomitant blocking was associated with greatly increased but completely independent jitter of both components. The results of this study show that both a disorder of neuromuscular transmission and an axolemmal dysfunction play a role in the pathophysiology of GB

Antibodies to voltage-gated potassium and calcium channels in epilepsy.

Item does not contain fulltextOBJECTIVE: To determine the prevalence of antibodies to ion channels in patients with long standing epilepsy. BACKGROUND: Although the CNS is thought to be protected from circulating antibodies by the blood brain barrier, glutamate receptor antibodies have been reported in Rasmussen's encephalitis, glutamic acid decarboxylase (GAD) antibodies have been found in a few patients with epilepsy, and antibodies to voltage-gated potassium channels (VGKC) have been found in a non-paraneoplastic form of limbic encephalitis (with amnesia and seizures) that responds to immunosuppressive therapy. METHODS: We retrospectively screened sera from female epilepsy patients (n=106) for autoantibodies to VGKC (Kv 1.1, 1.2 or 1.6), voltage-gated calcium channels (VGCC) (P/Q-type), and GAD. All positive results, based on the values of control data [McKnight, K., Jiang, Y., et al. (2005). Serum antibodies in epilepsy and seizure-associated disorders. Neurology 65, 1730-1735], were retested at lower serum concentrations, and results compared with previously published control data. Demographics, medical history, and epilepsy related information was gathered. RESULTS: The studied group consisted predominantly of patients with long standing drug resistant epilepsy. VGKC antibodies were raised (>100 pM) in six patients. VGCC antibodies (>45 pM) were slightly raised in only one patient. GAD antibodies were <3 U/ml in all patients. The clinical features of the patients with VGKC antibodies differed from previously described patients with limbic encephalitis-like syndrome, and were not different with respect to seizure type, age at first seizure, duration of epilepsy, or use of anti-epileptic drugs from the VGKC antibody negative patients. CONCLUSION: The results demonstrate that antibodies to VGKC are present in 6% of patients with typical long-standing epilepsy, but whether these antibodies are pathogenic or secondary to the primary disease process needs to be determined

Acquired neuromyotonia: superiority of plasma exchange over high-dose intravenous human immunoglobulin.

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Inflammatory markers predict late cardiac events in patients who are exhausted after percutaneous coronary intervention.

Contains fulltext : 48049.pdf (publisher's version ) (Closed access)Chronic inflammation is one of the main underlying mechanisms in the development of coronary artery disease (CAD). We investigated the prognostic value of inflammatory markers for cardiac events occurring more than 6 months after percutaneous coronary intervention (PCI), i.e. late cardiac events, furthermore we investigated the temporal stability of these markers. Exhausted patients (234) recently treated by successful PCI were studied. Serum samples collected about 6 weeks after PCI (baseline), 6 and 18 months after baseline were analyzed for CRP, IL-6, tumour necrosis factor (TNF-alpha), IL-10, IL-1ra, IL-8 and neopterin. In the mean cardiac follow-up of 24 months, 25 late cardiac events occurred. Cox proportional hazards analysis was used to determine the prognostic value. Elevated concentrations of IL-6 at baseline and 6 months later increased the risk of late cardiac events (RR 3.9, CI 1.7-9.0, p 0.00 and RR 3.6, CI 1.6-8.5, p 0.00). Elevated concentrations of CRP and IL-10 at baseline also increased the risk of late cardiac events (RR 2.5, CI 1.1-5.7, p 0.04 and RR 2.5, CI 1.1-5.6, p 0.03) as did IL-1 receptor antagonist at 6 months (RR 2.6, CI 1.1-6.1, p 0.04). Temporal stability was high for most markers, but highest for IL-6. These results support the assumption that chronic inflammation is a pathophysiological mechanism in the development of CAD

Muscle-specific kinase myasthenia gravis IgG4 autoantibodies cause severe neuromuscular junction dysfunction in mice.

Myasthenia gravis is a paralytic disorder with autoantibodies against acetylcholine receptors at the neuromuscular junction. A proportion of patients instead has antibodies against muscle-specific kinase, a protein essential for acetylcholine receptor clustering. These are generally of the immunoglobulin-G4 subclass and correlate with disease severity, suggesting specific myasthenogenic activity. However, immunoglobulin-G4 subclass antibodies are generally considered to be 'benign' and direct proof for their pathogenicity in muscle-specific kinase myasthenia gravis (or other immunoglobulin-G4-associated disorders) is lacking. Furthermore, the exact electrophysiological synaptic defects caused at neuromuscular junctions by human anti-muscle-specific kinase autoantibodies are hitherto unknown. We show that purified immunoglobulin-G4, but not immunoglobulin-G1-3, from patients with muscle-specific kinase myasthenia gravis binds to mouse neuromuscular junctions in vitro, and that injection into immunodeficient mice causes paralysis. Injected immunoglobulin-G4 caused reduced density and fragmented area of neuromuscular junction acetylcholine receptors. Detailed electrophysiological synaptic analyses revealed severe reduction of postsynaptic acetylcholine sensitivity, and exaggerated depression of presynaptic acetylcholine release during high-rate activity, together causing the (fatigable) muscle weakness. Intriguingly, compensatory transmitter release upregulation, which is the normal homeostatic response in acetylcholine receptor myasthenia gravis, was absent. This conveys extra vulnerability to neurotransmission at muscle-specific kinase myasthenia gravis neuromuscular junctions. Thus, we demonstrate that patient anti-muscle-specific kinase immunoglobulin-G4 is myasthenogenic, independent of additional immune system components, and have elucidated the underlying electrophysiological neuromuscular junction abnormalities