The pore-forming alpha subunits of many ion channels are associated with auxiliary subunits that influence channel expression, targeting, and function. Several different auxiliary (beta) subunits for large conductance calcium-dependent potassium channels of the Slowpoke family have been reported, but none of these beta subunits is expressed extensively in the nervous system. We describe here the cloning and functional characterization of a novel Slowpoke beta4 auxiliary subunit in human and mouse, which exhibits only limited sequence homology with other beta subunits. This beta4 subunit coimmunoprecipitates with human and mouse Slowpoke. beta4 is expressed highly in human and monkey brain in a pattern that overlaps strikingly with Slowpoke alpha subunit, but in contrast to other Slowpoke beta subunits, it is expressed little (if at all) outside the nervous system. Also in contrast to other beta subunits, beta4 downregulates Slowpoke channel activity by shifting its activation range to more depolarized voltages and slowing its activation kinetics. beta4 may be important for the critical roles played by Slowpoke channels in the regulation of neuronal excitability and neurotransmitter release.
Abdominal pregnancy is a rare variant of ectopic pregnancy which occurs when the gestational sac is implanted outside the uterus, ovaries and fallopian tubes. It constitutes approximately 1% of ectopic pregnancies, 1 and has a reported incidence of one in 2200 to one in 10,200 of all pregnancies, and one in 6000 births. 2 While abdominal pregnancies may reach term the fetal mortality rate varies from 30% to 95% 3,4 and the maternal mortality rate can be as high as 20%. 2 The fetal abnormality rates range from 30% to 100%, most of which are secondary to oligohydramnios and a constricted extrauterine environment, such as lung hypoplasia and pressure related deformities. 2 Hence, with the high risk to the mother and the improbability of a normal, viable fetus, immediate termination and removal of the pregnancy is advisable. Although successful non-surgical management of abdominal pregnancy has been reported, 5 surgical management is usually required. While this is traditionally done via a laparotomy, there have been five cases of laparoscopic management of abdominal pregnancy reported in the English literature.We report the identification and laparoscopic management of an early primary abdominal pregnancy. To the best of our knowledge, this is the first report in Australia of an abdominal pregnancy managed laparoscopically.
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