HNF3beta and GATA-4 transactivate the liver-enriched homeobox gene, Hex.

The orphan homeobox gene, Hex, has a limited domain of expression which includes the developing and adult mouse liver. Hex is expressed in the developing liver coincident with the forkhead/winged helix transcription factor, Hepatocyte Nuclear Factor 3beta (HNF3beta). Although preliminary characterization of the mouse Hex promoter has recently been reported, the identity of the molecular regulators that drive liver expression is not known. We hypothesized that putative HNF3beta and GATA-4 elements within the Hex promoter would confer liver-enriched expression. A series of Hex promoter-driven luciferase reporter constructs were transfected in liver-derived HepG2 and fibroblast-like Cos cells+/-HNF3beta or GATA expression plasmids. The Hex promoter region from nt -235/+22 conferred basal activity in both HepG2 and Cos cells, with the region from -103/+22 conferring liver-enriched activity. HNF3beta and GATA-4 transactivated the promoter via response elements located within nt -103/+22, whereas Sp1 activated the -235/+22 construct. Mutation of the HNF3 element significantly reduced promoter activity in HepG2 cells, whereas this element in isolation conferred HNF3beta responsiveness to a heterologous promoter. Electrophoretic mobility shift assays were performed to confirm transcription factor:DNA binding. We conclude that HNF3beta and GATA-4 contribute to liver-enriched expression of Hex.

Interleukin-1beta suppresses retinoid transactivation of two hepatic transporter genes involved in bile formation.

Cytokines have been implicated in the pathogenesis of inflammatory cholestasis. This is due to transcriptional down-regulation of hepatic transporters including the Na(+)/bile acid cotransporter, ntcp, and the multispecific organic anion exporter, mrp2. We have recently shown that ntcp suppression by lipopolysaccharide in vivo is caused by down-regulation of transactivators including the previously uncharacterized Footprint B-binding protein. Both the ntcp FpB element and the mrp2 promoter contain potential retinoid-response elements. We hypothesized that retinoic acid receptor (RAR) and retinoid X receptor (RXR) heterodimers would activate these two genes and that cytokines that reduce bile flow might do so by suppressing nuclear levels of these transactivators. Retinoid transactivation and interleukin-1beta down-regulation of the ntcp and mrp2 promoters were mapped to RXRalpha:RARalpha-response elements. Gel mobility shift assays demonstrated specific binding of RXRalpha:RARalpha heterodimers to the ntcp and mrp2 retinoid-response elements. The RXRalpha:RARalpha complex was down-regulated by IL-1beta in HepG2 cells. An unexpected finding was that an adjacent CAAT-enhancer-binding protein element was required for maximal transactivation of the ntcp promoter by RXRalpha:RARalpha. Taken together, these studies demonstrate regulation of two hepatobiliary transporter genes by RXRalpha:RARalpha and describe a mechanism which likely contributes to their down-regulation during inflammation.

The frontal plane relationship of the forefoot to the rearfoot in an asymptomatic population.

Physical therapists use biochemical orthotics to treat symptoms attributed to structural abnormalities of the feet. The purpose of this study was to determine the prevalence of forefoot varus, valgus, and neutral positions in a healthy population, and to compare forefoot positions between genders, legs, and age groups. Nonprobability sampling was used to obtain 120 healthy subjects. A repeated-measures, one-group design was used. A forefoot measuring device and a goniometer were used to measure the forefoot-rearfoot frontal plane relationship. Of the 234 measured feet, 86.67% had a varus, 8.75% had a valgus, and 4.58% had a neutral forefoot-rearfoot relationship. No significant difference in position was found between genders or legs within subjects. A certain amount of forefoot varus or valgus may be characteristic of a healthy population; however, future studies should include children and adolescents to determine if forefoot positions are acquired or congenital.

Sequential isokinetic and manual muscle testing in patients with neuromuscular disease. A pilot study.

The purposes of this study were to compare the value of isokinetic testing and manual muscle testing (MMT) in longitudinal measurements of muscle strength in patients with neuromuscular disease and to identify any consistent pattern demonstrated by the isokinetic testing of patients with specific diagnoses. We measured knee extensor muscle strength at periodic intervals in patients, using MMT and isokinetic testing at angular limb velocities of 30 and 180 degrees/sec. An isokinetic fatigability test also was conducted. The results indicated that in patients who were graded 9 to 10 (ie, within normal limits) by MMT methods, sequential isokinetic strength tests revealed improvement not indicated by MMT. In patients, however, having weakness detectable by MMT and whose course was deteriorating, isokinetic testing did not seem to add clinically significant information for long-term management. Some patients with myotonia demonstrated an increase in peak torque during the fatigability test; this response was unique among the diagnoses we tested. Isokinetic testing may provide, in some patients with neuromuscular disease, valuable information when used in conjunction with MMT for sequential monitoring of strength. Continued research is needed to investigate the value of isokinetic testing in the diagnosis and management of patients with neuromuscular disease.