Publications by authors named "N G Greeff"

Purpose: Studies of the outcome of hypospadias repair must document quality, including assessment of complications and appraisal of appearance. To our knowledge the Pediatric Penile Perception Score is the first validated instrument for the outcome assessment of hypospadias repair in prepubertal males by surgeons and patients. We validated the instrument for adult genitalia.

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The aim of the present study was to investigate in detail how the voltage sensor in the Shaker potassium channel moves during the gating process. After the publication of the open channel structure from the crystallized K(V)AP channel in 2003, an alternative so-called "paddle" model was put forward in contrast to the existing helical screw model. The voltage sensor S4 contains 4 arginine residues relevant for gating, R1(362), R2(365), R3(368) and R4(371), each separated by 2 neutral residues.

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This study presents what is, to our knowledge, a novel technique by means of which the ratio of the single gating charges of voltage-gated rat brain IIA (rBIIA) sodium and Shaker potassium ion channels was estimated. In the experiment, multiple tandems of enhanced green fluorescent protein were constructed and inserted into the C-terminals of Na(+) and K(+) ion channels. cRNA of Na(+) and K(+) ion channels was injected and expressed in Xenopus laevis oocytes.

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In voltage-dependent sodium channels there is some functional specialization of the four different S4 voltage sensors with regard to the gating process. Whereas the voltage sensors of domains 1 to 3 control activation gating, the movement of the voltage sensor of domain 4 (S4D4) is known to be tightly coupled to sodium channel inactivation, and there is some experimental evidence that S4D4 also participates in activation gating. To further explore its putative multifunctional role in the gating process, we changed the central part of S4D4 in rat brain IIA (rBIIA) sodium channels by the simultaneous replacement of the third (R1632), fourth (R1635) and fifth (R1638) arginine by histidine (mutation R3/4/5H).

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Cardiac voltage-dependent sodium channels (Na(v)) are drug targets for synthetic inactivation inhibitors typified by (+/-)-4- [3-(4-diphenylmethyl-1-piperazinyl)-2-hydroxy propoxy]-1H-indole-2-carbonitrile (DPI 201-106), of which the molecular mode of action is not yet defined. The previous observation by Mevissen and coworkers in 2001 of the electrophysiological ineffectiveness of DPI 201-106 in the bovine heart, in contrast to other species, offers the opportunity for investigating these open questions. We now report about the molecular cloning, expression in Xenopus laevis oocytes, and electrophysiological characterization of a unique bovine heart sodium channel.

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