Co-localization and interaction of human organic anion transporter 4 with caveolin-1 in primary cultured human placental trophoblasts

The human organic anion transporter 4 (hOAT4) has been identified as the fourth isoform of OAT family. hOAT4 contributes to move several negatively charged organic compounds between cells and their extracellular milieu. The functional characteristics and regulatory mechanisms of hOAT4 remain to be elucidated. It is well known that caveolin plays a role in modulating proteins having some biological functions. To address this issue, we investigated the co-localization and interaction between hOAT4 and caveolin-1. hOAT4 and caveolin-1 (mRNA and protein expression) were observed in cultured human placental trophoblasts isolated from placenta. The confocal microscopy of immuno-cytochemistry using primary cultured human trophoblasts showed hOAT4 and caveolin-1 were co-localized at the plasma membrane of the cell. This finding was confirmed by Western blot analysis using isolated caveolae-enriched membrane fractions and immune-precipitates from the trophoblasts. When synthesized cRNA of hOAT4 along with scrambled- or antisense-oligodeoxynucleotide (ODN) of Xenopus caveolin-1 were co-injected to Xenopus oocytes, the [3H]estrone sulfate uptake was significantly decreased by the co-injection of antisense ODN but not by scrambled ODN. These findings suggest that hOAT4 and caveolin-1 share a cellular expression in the plasma membrane and caveolin-1 up-regulates the organic anionic compound uptake by hOAT4 under the normal physiological condition.

Optimal Sampling of Muscles to Detect Lumbosacral Radiculopathy

OBJECTIVE: To determine the optimal number of muscles to detect lumbosacral radiculopathies. METHOD: Electrodiagnostic data of 152 patients who had been diagnosed as lumbosacral radiculopathy with the findings of operative record were obtained retrospectively. The findings of needle electromyography were reviewed and the frequency of abnormal spontaneous activities in L5 and S1 myotomes was investigated. We selected 8 individual muscles which had high sampling rate. These muscles were combined into different muscle screens and the detection rates were calculated that the frequency with which one or more muscles in the screen displayed abnormal spontaneous activity was divided by the total number of radiculopathies. RESULTS: The detection rates of lumbosacral radiculopathy were compared according to the number of muscle screens. Including paraspinal muscle, the detection rate of 6 muscle screens was higher than 5 muscle screens (p<0.05), but there was no significant difference of detection rate between 6 muscle screens and 7 muscle screens. The detection rates of each muscle screens without paraspinal muscle were lower than those including paraspinal muscle for all screens (p<0.05). CONCLUSION: Although there is controversy about selection of muscles, six muscle screen including paraspinal muscles may be optimal number for detecting lumbosacral radiculopathy.