A Synthetic Chloride Channel Restores Chloride Conductance in Human Cystic Fibrosis Epithelial Cells

Mutations in the gene-encoding cystic fibrosis transmembrane conductance regulator (CFTR) cause defective transepithelial transport of chloride (Cl−) ions and fluid, thereby becoming responsible for the onset of cystic fibrosis (CF). One strategy to reduce the pathophysiology associated with CF is to increase Cl− transport through alternative pathways. In this paper, we demonstrate that a small synthetic molecule which forms Cl− channels to mediate Cl− transport across lipid bilayer membranes is capable of restoring Cl− permeability in human CF epithelial cells; as a result, it has the potential to become a lead compound for the treatment of human diseases associated with Cl− channel dysfunction

The K+ Channel Opener 1-EBIO Potentiates Residual Function of Mutant CFTR in Rectal Biopsies from Cystic Fibrosis Patients

BACKGROUND: The identification of strategies to improve mutant CFTR function remains a key priority in the development of new treatments for cystic fibrosis (CF). Previous studies demonstrated that the K⁺ channel opener 1-ethyl-2-benzimidazolone (1-EBIO) potentiates CFTR-mediated Cl⁻ secretion in cultured cells and mouse colon. However, the effects of 1-EBIO on wild-type and mutant CFTR function in native human colonic tissues remain unknown. METHODS: We studied the effects of 1-EBIO on CFTR-mediated Cl⁻ secretion in rectal biopsies from 47 CF patients carrying a wide spectrum of CFTR mutations and 57 age-matched controls. Rectal tissues were mounted in perfused micro-Ussing chambers and the effects of 1-EBIO were compared in control tissues, CF tissues expressing residual CFTR function and CF tissues with no detectable Cl⁻ secretion. RESULTS: Studies in control tissues demonstrate that 1-EBIO activated CFTR-mediated Cl⁻ secretion in the absence of cAMP-mediated stimulation and potentiated cAMP-induced Cl⁻ secretion by 39.2±6.7% (P<0.001) via activation of basolateral Ca²⁺-activated and clotrimazole-sensitive KCNN4 K⁺ channels. In CF specimens, 1-EBIO potentiated cAMP-induced Cl⁻ secretion in tissues with residual CFTR function by 44.4±11.5% (P<0.001), but had no effect on tissues lacking CFTR-mediated Cl⁻ conductance. CONCLUSIONS: We conclude that 1-EBIO potentiates Cl⁻secretion in native CF tissues expressing CFTR mutants with residual Cl⁻ channel function by activation of basolateral KCNN4 K⁺ channels that increase the driving force for luminal Cl⁻ exit. This mechanism may augment effects of CFTR correctors and potentiators that increase the number and/or activity of mutant CFTR channels at the cell surface and suggests KCNN4 as a therapeutic target for CF

Locally Administrated Perindopril Improves Healing in an Ovariectomized Rat Tibial Osteotomy Model

Angiotensin-converting enzyme inhibitors are widely prescribed to regulate blood pressure. High doses of orally administered perindopril have previously been shown to improve fracture healing in a mouse femur fracture model. In this study, perindopril was administered directly to the fracture area with the goal of stimulating fracture repair. Three months after being ovariectomized (OVX), tibial fractures were produced in Sprague–Dawley rats and subsequently stabilized with intramedullary wires. Perindopril (0.4 mg/kg/day) was injected locally at the fractured site for a treatment period of 7 days. Vehicle reagent was used as a control. Callus quality was evaluated at 2 and 4 weeks post-fracture. Compared with the vehicle group, perindopril treatment significantly increased bone formation, increased biomechanical strength, and improved microstructural parameters of the callus. Newly woven bone was arranged more tightly and regularly at 4 weeks post-fracture. The ultimate load increased by 66.1 and 76.9% (p<0.01), and the bone volume over total volume (BV/TV) increased by 29.9% and 24.3% (p<0.01) at 2 and 4 weeks post-fracture, respectively. These findings suggest that local treatment with perindopril could promote fracture healing in ovariectomized rats

Design of 5.0-GHz KSTAR lower-hybrid coupler

The Korean Superconducting Tokamak Advanced Research (KSTAR) tokamak is being constructed to perform long-pulse, high-beta, advanced tokamak fusion physics experiments by Korean Basic Science Institute (KBSI). The KSTAR tokamak will use the non-inductive plasma current drive system, lower-hybrid current drive (LHCD) system for lone-pulse operation. A 5.0-GHz microwave coupler is designed for KSTAR LHCD experiments. Four high-power klystrons feed 128 guidelets at front coupler using hundred and twenty 3-dB power dividers including 3-dB power splitters in the coupler. The guidelet has a height of 5.5 cm and the width of 0.55 cm in order for the power flux density not to exceed 4.0 kW/cm(2) at the guidelet. The coupler is constructed by laminating a stack of metal plates milled to waveguide patterns. This paper describes detailed design for the 3-dB power splitter, the fixed-phase shifter, and the taper section composing the coupler. Using the High Frequency Structure Simulator (HFSS) program, we achieved a phase difference of +/-0.5degrees and a relative power difference less than 0.2% between two vertical guidelets. (C) 2003 Elsevier Science B.V. All rights reserved.1111sciescopu

Design of 5.0-GHz KSTAR lower-hybrid coupler

The Korean Superconducting Tokamak Advanced Research (KSTAR) tokamak is being constructed to perform long-pulse, high-beta, advanced tokamak fusion physics experiments by Korean Basic Science Institute (KBSI). The KSTAR tokamak will use the non-inductive plasma current drive system, lower-hybrid current drive (LHCD) system for lone-pulse operation. A 5.0-GHz microwave coupler is designed for KSTAR LHCD experiments. Four high-power klystrons feed 128 guidelets at front coupler using hundred and twenty 3-dB power dividers including 3-dB power splitters in the coupler. The guidelet has a height of 5.5 cm and the width of 0.55 cm in order for the power flux density not to exceed 4.0 kW/cm(2) at the guidelet. The coupler is constructed by laminating a stack of metal plates milled to waveguide patterns. This paper describes detailed design for the 3-dB power splitter, the fixed-phase shifter, and the taper section composing the coupler. Using the High Frequency Structure Simulator (HFSS) program, we achieved a phase difference of +/-0.5degrees and a relative power difference less than 0.2% between two vertical guidelets. (C) 2003 Elsevier Science B.V. All rights reserved.

Requirement for the L-type Ca2+ channel alpha(1D) subunit in postnatal pancreatic beta cell generation

Pancreatic 5 cells are the source of insulin, which directly lowers blood glucose levels in the body. Our analyses Of alpha (1D) gene-knockout (alpha (1D-/-)) mice show that the L-type calcium channel, alpha (1D), is required for proper beta cell generation in the postnatal pancreas. Knockout mice were characteristically slightly smaller than their littermates and exhibited hypoinsulinemia and glucose intolerance. However, isolated a(1D)(-/-) islets persisted in glucose sensing and insulin secretion, with compensatory overexpression of another L-type channel gene, alpha (1C). Histologically, newborn a(1D)(-/-) mice had an equivalent number of islets to wild-type mice. in contrast, adult alpha (-/-)(1D) mice showed a decrease in the number and size of islets, compared with littermate wild-type mice due to a decrease in beta cell generation. TUNEL staining showed that there was no increase in cell. death in alpha (-/-)(1D) islets, and a 5-bromo-2 &apos; deoxyuridine-labeling (BrdU-labeling) assay illustrated significant reduction in the proliferation rate of beta cells in alpha (-/-)(1D) islets.open798