| 1. |
- Beyder, Arthur, et al.
(författare)
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Loss-of-Function of the Voltage-Gated Sodium Channel Na(V)1.5 (Channelopathies) in Patients With Irritable Bowel Syndrome
- 2014
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Ingår i: Gastroenterology. - : Elsevier BV. - 0016-5085 .- 1528-0012. ; 146:7, s. 1659-1668
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: SCN5A encodes the a-subunit of the voltage-gated sodium channel Na(V)1.5. Many patients with cardiac arrhythmias caused by mutations in SCN5A also have symptoms of irritable bowel syndrome (IBS). We investigated whether patients with IBS have SCN5A variants that affect the function of Na(V)1.5. METHODS: We performed genotype analysis of SCN5A in 584 persons with IBS and 1380 without IBS (controls). Mutant forms of SCN5A were expressed in human embryonic kidney-293 cells, and functions were assessed by voltage clamp analysis. A genome-wide association study was analyzed for an association signal for the SCN5A gene, and replicated in 1745 patients in 4 independent cohorts of IBS patients and controls. RESULTS: Missense mutations were found in SCN5A in 13 of 584 patients (2.2%, probands). Diarrhea-predominant IBS was the most prevalent form of IBS in the overall study population (25%). However, a greater percentage of individuals with SCN5A mutations had constipation-predominant IBS (31%) than diarrhea-predominant IBS (10%; P < .05). Electrophysiologic analysis showed that 10 of 13 detected mutations disrupted Na(V)1.5 function (9 loss-of-function and 1 gain-of-function function). The p. A997T-Na(V)1.5 had the greatest effect in reducing Na(V)1.5 function. Incubation of cells that expressed this variant with mexiletine restored their sodium current and administration of mexiletine to 1 carrier of this mutation (who had constipation-predominant IBS) normalized their bowel habits. In the genome-wide association study and 4 replicated studies, the SCN5A locus was strongly associated with IBS. CONCLUSIONS: About 2% of patients with IBS carry mutations in SCN5A. Most of these are loss-of-function mutations that disrupt Na(V)1.5 channel function. These findings provide a new pathogenic mechanism for IBS and possible treatment options.
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| 2. |
- Beyder, Arthur, et al.
(författare)
-
Loss-of-function of the voltage-gated sodium channel NaV1.5 (channelopathies) in patients with irritable bowel syndrome.
- 2014
-
Ingår i: Gastroenterology. - : Elsevier BV. - 0016-5085 .- 1528-0012. ; 146:7
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: SCN5A encodes the α-subunit of the voltage-gated sodium channel NaV1.5. Many patients with cardiac arrhythmias caused by mutations in SCN5A also have symptoms of irritable bowel syndrome (IBS). We investigated whether patients with IBS have SCN5A variants that affect the function of NaV1.5.METHODS: We performed genotype analysis of SCN5A in 584 persons with IBS and 1380 without IBS (controls). Mutant forms of SCN5A were expressed in human embryonic kidney-293 cells, and functions were assessed by voltage clamp analysis. A genome-wide association study was analyzed for an association signal for the SCN5A gene, and replicated in 1745 patients in 4 independent cohorts of IBS patients and controls.RESULTS: Missense mutations were found in SCN5A in 13 of 584 patients (2.2%, probands). Diarrhea-predominant IBS was the most prevalent form of IBS in the overall study population (25%). However, a greater percentage of individuals with SCN5A mutations had constipation-predominant IBS (31%) than diarrhea-predominant IBS (10%; P < .05). Electrophysiologic analysis showed that 10 of 13 detected mutations disrupted NaV1.5 function (9 loss-of-function and 1 gain-of-function function). The p. A997T-NaV1.5 had the greatest effect in reducing NaV1.5 function. Incubation of cells that expressed this variant with mexiletine restored their sodium current and administration of mexiletine to 1 carrier of this mutation (who had constipation-predominant IBS) normalized their bowel habits. In the genome-wide association study and 4 replicated studies, the SCN5A locus was strongly associated with IBS.CONCLUSIONS: About 2% of patients with IBS carry mutations in SCN5A. Most of these are loss-of-function mutations that disrupt NaV1.5 channel function. These findings provide a new pathogenic mechanism for IBS and possible treatment options.
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| 3. |
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| 4. |
- Gena, Patrizia, et al.
(författare)
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Stopped-flow Light Scattering Analysis of Red Blood Cell Glycerol Permeability
- 2020
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Ingår i: Bio-protocol. - 2331-8325. ; 10:16
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Tidskriftsartikel (refereegranskat)abstract
- Stopped-Flow Light Scattering (SFLS) is a method devised to analyze the kinetics of fast chemical reactions that result in a significant change of the average molecular weight and/or in the shape of the reaction substrates. Several modifications of the original stopped-flow system have been made leading to a significant extension of its technical applications. One of these modifications allows the biophysical characterization of the water and solute permeability of biological and artificial membranes. Here, we describe a protocol of SFLS to measure the glycerol permeability of isolated human red blood cells (RBCs) and evaluate the pharmacokinetics properties (selectivity and potency) of isoform-specific inhibitors of AQP3, AQP7 and AQP9, three mammalian aquaglyceroporins allowing transport of glycerol across membranes. Suspensions of RBCs (1% hematocrit) are exposed to an inwardly directed gradient of 100 mM glycerol in a SFLS apparatus at 20 °C and the resulting changes in scattered light intensity are recorded at a monochromatic wavelength of 530 nm for 120 s. The SFLS apparatus is set up to have a dead time of 1.6-ms and 99% mixing efficiency in less than 1 ms. Data are fitted to a single exponential function and the related time constant (τ, seconds) of the cell-swelling phase of light scattering corresponding to the osmotic movement of water that accompanies the entry of glycerol into erythrocytes is measured. The coefficient of glycerol permeability (Pgly, cm/s) of RBCs is calculated with the following equation: Pgly = 1/[(S/V)τ] where τ (s) is the fitted exponential time constant and S/V is the surface-to-volume ratio (cm-1) of the analyzed RBC specimen. Pharmacokinetics of the isoform-specific inhibitors of AQP3, AQP7 and AQP9 are assessed by evaluating the extent of RBC Pgly values resulting after the exposure to serial concentrations of the blockers.
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| 5. |
- Giannelli, Gianluigi, et al.
(författare)
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The rationale for targeting TGF-beta in chronic liver diseases
- 2016
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Ingår i: European Journal of Clinical Investigation. - : Wiley. - 0014-2972 .- 1365-2362. ; 46:4, s. 349-361
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Forskningsöversikt (refereegranskat)abstract
- BackgroundTransforming growth factor (TGF)- is a pluripotent cytokine that displays several tissue-specific biological activities. In the liver, TGF- is considered a fundamental molecule, controlling organ size and growth by limiting hepatocyte proliferation. It is involved in fibrogenesis and, therefore, in worsening liver damage, as well as in triggering the development of hepatocellular carcinoma (HCC). TGF- is known to act as an oncosuppressor and also as a tumour promoter in HCC, but its role is still unclear. DesignIn this review, we discuss the potential role of TGF- in regulating the tumoural progression of HCC, and therefore the rationale for targeting this molecule in patients with HCC. ResultsA considerable amount of experimental preclinical evidence suggests that TGF- is a promising druggable target in patients with HCC. To support this hypothesis, a phase II clinical trial is currently ongoing using a TGF- pathway inhibitor, and results will soon be available. ConclusionsThe identification of new TGF- related biomarkers will help to select those patients most likely to benefit from therapy aimed at inhibiting the TGF- pathway. New formulations that may provide a more controlled and sustained delivery of the drug will improve the therapeutic success of such treatments.
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