Calcium movement in smooth muscle and evaluation of graded functional intercellular coupling.

Spontaneous activity of vascular smooth muscle is present in small arteries and some venous tissues like the hepatic portal vein. Whereas the ability to generate rhythmic membrane potential changes is expressed in a high number of primary oscillators, the generation of physiological tone and phasic activity requires synchronization of specialized pacemaker activity (Interstitial Cajal-like cells) by intercellular propagation and regeneration of excitation or a strong coupling mechanism of smooth muscle cells. The aim of this study was to deduce oscillator coupling by analyzing the spatiotemporal homogeneity of calcium oscillations within a native tissue preparation. Portal vein tissue was loaded with a calcium-sensitive dye (Fluo-3). By combining confocal microscopy and computation of spatial auto- and cross-correlation of the calcium signals, temporal and spatial coupling between cells was characterized. Spontaneous oscillations of calcium signals were measured at different predefined regions of interest. Cross-correlation analysis of these signals revealed that their damping was very similar in all directions of the investigated z-plane. In single experiments, improved cell-to-cell coupling was seen when noradrenaline (1-10 µM) was added to the bath-solution. With the chosen parameters of frame refresh, the velocity of signal propagation was faster than the maximum detectable velocity, but it could be estimated to exceed 0.1 mm/s. Correlative Network Analysis is a new and very useful tool to determine the functional coupling parameters of quasi-homogenous biological networks and their temporal changes. The action and significance of pharmacological modulators can be well studied on cellular and functional aspects with this newly introduced technique in biological sciences.

The sphingosine analog fingolimod (FTY720) enhances tone and contractility of rat gastric fundus smooth muscle.

BACKGROUND: Sphingosine and its metabolite sphingosine phosphate (S1P) regulate a multitude of biological functions, including the contractile state of smooth. Gastrointestinal side effects have been reported in patients treated with FTY720, a sphingosine analog that is approved for the treatment of multiple sclerosis. The aim of this study was to characterize the effects of FTY720 on rat gastric fundus smooth muscle under basal conditions and during activation induced by high-K+ solution. METHODS: Isometric contractions of isolated circular strips of gastric fundus smooth muscle were recorded using the organ bath method. The effects of FTY720 or vehicle were recorded under control conditions and in the presence of indomethacin, L-NAME, HA-1100, nifedipine, JTE-013, and suramin. Tone and contractions recorded in the presence of FTY720 or vehicle are reported as % of the amplitude of an initial high-K+ contraction obtained under control conditions. KEY RESULTS: From a concentration of 10 µmol L-1 onwards, FTY720 increased the tone, reaching 8.9% ± 7.5% at 100 µmol L-1 (P < .05). With indomethacin in the solution, the effects of FTY720 were enhanced (32.1% ± 7.7%; P < .001). The FTY720-induced increase in tone was abolished in the absence of extracellular Ca2+ and reduced by nifedipine, HA-1100, JTE-013, and suramin. Furthermore, FTY720 increased high-K+ contractions in the presence of indomethacin. CONCLUSIONS & INFERENCES: FTY720 increases tone and contractile responses to depolarization in gastric fundus smooth muscle by triggering calcium entry and calcium sensitization in a S1P receptor-dependent manner. Taken together, the experimental results presented in this work suggest that FTY720 may increase gastric tone and contractility in patients.

[Autoimmune-Mediated Encephalomyelitis: a Heterogeneous Entity in Between Neurology and Psychiatry]. / Autoimmunvermittelte Enzephalomyelitiden: Eine heterogene Krankheitsgruppe zwischen Psychiatrie und Neurologie.

Within the last decade, autoantibody-associated encephalitis and encephalomyelitis have stepped into the focus of clinical research and practice. Besides the "classic" autoantibodies against intracellular neuronal antigenes, a growing number of antibodies directed against pre- and postsynaptic surface proteins of neurons have been described since the millennium change. Whereas the "classic" are closely linked to paraneoplastic syndromes, this association is loose for most of the yet known surface antigen-antibodies. The immune-mediated encephalomyelitic syndromes are thus classified not only by their clinical symptoms, but also by their specific antibodies. The definition of the entity of N-methyl-D-aspartate-receptor encephalitis is a prominent example. The presented work gives an overview on the clinical and pathological correlates and the underlying immunologic processes of autoantibody-associated encephalitis from a neuropsychiatric perspective.

[Diagnostic Workup and Treatment of Antibody-Related Encephalomyelitis]. / Diagnostik und Therapie von autoantikörpervermittelten Enzephalomyelitiden.

The results of laboratory tests for antineuronal antibodies in immune-mediated encephalitis nowadays are not only relevant for diagnostic purposes but are instead closely connected to outcome measures and treatment response. Besides the mere detection of antibodies, investigating the cerebrospinal fluid is indispensible to rule out an infectious etiology of encephalitis prior to the initiation of immunosuppressive treatment, whereas imaging studies are relevant to gain information on the temporal course of disease and for ruling out other etiologies, e. g. hippocampal gliomas. This work gives an overview on the clinical course and findings of laboratory, electroencephalography (EEG) and imaging studies in relevant types of autoimmune mediated encephalitis. Furthermore, it gives a synopsis on contemporary treatment strategies.

Neuromyelitis optica spectrum disorder coinciding with hematological immune disease: A case report.

INTRODUCTION: Recently defined consensus criteria for the diagnosis of neuromyelitis optica spectrum disorders (NMOSD) allow establishing the diagnosis in patients without elevated AQP4-Ab and optic nerve involvement. According to the new extended definition, NMOSD is closely associated with extensive spinal cord inflammation occurring in the course of systemic autoimmune diseases as sarcoidosis or lupus erythematodes. NMOSD occurring in the course of hematological disease have not yet been reported in the literature. CASE REPORT: A 38 year old male subsequently developed thrombocytopenia, hemolytic anemia and agranulocytosis over a 23 month period. Three months after an episode of agranulocytosis, he noticed ascending sensory disturbances and progressive weakness of his legs. Within two days, symptoms worsened to give almost complete paraplegia and loss of sensation below a midthoracic level. MRI revealed signal hyperintensity and edema in T2-weighted sequences reaching from the 2nd cervical to the 9th thoracic vertebral body. Two years later, he developed a second episode with lesions in the spinal cord and periventricular areas of brain stem and thalamus. CONCLUSION: The relapsing time course and the topographical pattern of central nervous system lesions restricted to axial brain structures and the spinal cord fulfill the criteria that have recently been defined for AQP4-Ab-negative NMO-spectrum disease. Systematic studies on the association of hematological autoimmune phenomena and spinal cord disease are needed to clarify whether this coincidence is just a casual phenomenon or whether it points to a yet undiscovered but perhaps therapeutically interesting link of immunological mechanisms affecting both organ systems.

Phenytoin inhibits contractions of rat gastrointestinal and portal vein smooth muscle by inhibiting calcium entry.

BACKGROUND: Phenytoin is widely used as a second-line treatment for status epilepticus. Besides its well-known cardiac pro-arrhythmogenicity, side effects on other organ systems have received less attention. METHODS: This study investigates the effects of phenytoin on gastrointestinal tissue function using an in vitro model of smooth muscle preparations from rats by combining registrations of pharmacological effects on mechanical contractions, electric field potentials, and dynamic intravital fluorescence microscopy. KEY RESULTS: When added to the bathing solution at a concentration of 30 µM, phenytoin reduced the frequency of spontaneous activity significantly in antrum and portal vein preparations to 72.2 ± 36.5% (p = 0.022) and 80.7 ± 24.4% (p = 0.037) of control values, respectively. At a concentration of 100 µM, the height of spontaneous contractions declined to 9.8 ± 19.6% (p = 0.005) (antrum), 15.7 ± 28.2% (p = 0.004) (portal vein), and 31.8 ± 31.3% (p = 0.005) (colon) in comparison to the control conditions before the application of phenytoin. Depolarization triggered increases in calcium dependent fluorescence signals were reduced by 52.8 ± 39.1% (p = 0.012) The inhibition of spontaneous activity caused by phenytoin was reduced in the presence of the L-type calcium channel agonist BAY K8644(-). CONCLUSIONS & INFERENCES: Phenytoin exerts strong inhibitory effects on the spontaneous and stimulated contractile activity of smooth muscles from both the upper and lower gastrointestinal tract. The mechanism underlying this effect is not related to the sodium channel blocking activity of phenytoin, but is rather caused by an inhibition of calcium entry through voltage dependent L-type calcium channels. The results of this study should raise vigilance to gastrointestinal complications in patients treated with phenytoin.

[Fatigue in patients with multiple sclerosis--pathogenesis, clinical picture, diagnosis and treatment]. / Fatigue bei Patienten mit Multipler Sklerose--Pathogenese, Klinik, Diagnostik und Therapie.

Fatigue is a frequent and restricting symptom of multiple sclerosis (MS). Starting from its pathogenetic mechanisms, the article develops an approach to the differential diagnosis of fatigue in MS patients. Over the past years, the use of functional imaging techniques has given important information on the mechanisms of this highly variable clinical picture. Considering our improved understanding of the interdependency of immune pathology and the clinical presentation of neuropsychological disorders, the relationship between immunomodulatory treatments and fatigue is receiving increased attention. Therefore, this article not only reports on the most recent data on pharmacological, physical and psychological interventions in the symptomatic treatment of fatigue, but also puts a special accent on data concerning the interactions between the rapidly growing number of immunomodulatory treatments in MS.

[Multiple sclerosis, neuromyelitis optica and spasticity: control of specific symptoms and quality of life]. / Multiple Sklerose, Neuromyelitis optica und spastische Bewegungsstörungen: Spezifische Symptomkontrolle und Lebensqualität.

Spastic movement disorders show a high lifetime prevalence among patients suffering from multiple sclerosis and neuromyelitis optica. Due to the high number of factors interacting with the individual manifestations of spasticity, its symptomatic treatment affords continuous and careful balancing of therapeutic measures. A trend observed over the past few years is to base symptomatic treatment of MS on subjective assessments of functional disorders rather than on specific individual pathological signs and symptoms. This has led to a more generous and more patient-oriented perspective. Therefore, a detailed analysis, characterisation and evaluation of the individual clinical course of the disease is not only indispensable, but is actually gaining even more importance in avoiding uncontrolled polypharmacy with correspondingly increased risks for side effects.

Characterization of ion currents of murine CD117(pos) stem cells in vitro and their modulation under AT2 R stimulation.

AIM: Hematopoietic stem cells, especially CD117(pos) cells, have been found to possess a regenerative potential in various tissues, in particular cardiac muscle. However, the characterization of the relevant ion currents of stem cells prior to implantation lacks documentation. Activation of angiotensin II type 2 receptor (AT2 R) can lead to further cell differentiation and receptor auto-expression and might thus influence electrophysiological properties of CD117(pos) stem cells. This study was designed to functionally characterize membrane currents of CD117(pos) cells under normal and AT2 R-stimulated conditions. METHODS: CD117(pos) murine bone marrow stem cells were isolated with MACS technique and stimulated for the AT2 R with angiotensin II and losartan for 3-5 days prior to patch-clamp measurements. RT-PCR was used to determine channel expression. Endothelial properties were analysed with immunocytochemistry and acLDL uptake assay. RESULTS: A well-expressed inward rectifying current (IKir ) was identified in cultured CD117(pos) cells. Furthermore, a ZD 7288 (HCN channel blocker)-sensitive current component was isolated. Voltage-dependent potassium currents and chloride currents were less expressed. A small fraction of cells demonstrated voltage- and time-dependent inward currents. In AT2 R-stimulated cells inward rectifying the hyperpolarization-induced inward currents were slightly attenuated on the translational level but showed increased mRNA expression. Cultured CD117(pos) cells express CD31 and VEGFR-2 and significantly increased the uptake of acLDL. CONCLUSIONS: CD117(pos) cells do not have properties of action potential-generating cells and moderately change their excitability during AT2 R stimulation. Electrophysiological and molecular properties of control and AT2 R-stimulated cells point to a differentiation to vascular endothelial cells. This could increase beneficial vascularization in injured tissues.

Insular stroke is associated with acute sympathetic hyperactivation and immunodepression.

BACKGROUND AND PURPOSE: Post-stroke immunodepression has been related to brain lesion size but not a specific lesion location. Here, we studied the influence of lesion location within middle cerebral artery (MCA) territory on parameters related to activation of sympathetic adrenomedullar pathway, immunodepression, and associated infection. METHODS: We analyzed clinical, brain imaging, and laboratory data of 384 patients (174 women; mean age 70.8 ± 12.9 years) consecutively admitted to the stroke unit no later than 24 h after onset of acute ischaemic stroke involving the MCA territory. RESULTS: Patients with lesion affecting >33% of MCA territory had increased serum metanephrine and normetanephrine levels, elevated neutrophil counts but decreased eosinophil, helper T lymphocyte, and cytotoxic T lymphocyte counts compared to patients with lesion in <33% of MCA territory. Patients with large infarctions had increased frequency of infections within 14 days after stroke, especially chest infections (P < 0.001). Considering only patients with non-lacunar infarction in <33% of MCA territory, those with insular lesion had significantly higher normetanephrine levels, higher neutrophil but lower eosinophil and helper T lymphocyte counts than those with non-insular lesion, despite similar lesion diameters. This coincided with an increased frequency of chest infections (P < 0.01) in patients with insular lesion. Whilst patients with right insular lesion showed decreased heart rate variability, lesion laterality had no impact on laboratory findings or infection frequency. CONCLUSION: These findings suggest a specific role of insular lesion in the pathogenesis of stroke-induced sympathetic hyperactivation and immunodepression. Neuroimaging studies applying lesion volume calculation techniques are warranted to confirm these findings.