Relationships of CDXs and apical sodium-dependent bile acid transporter in Barrett's esophagus

Barrett's esophagus (BE) is characterized by intestinal metaplasia with the differentiated epithelium replaced by another type of epithelium morphologically similar to normal intestinal epithelium. The metaplasia is preceded by bile and acid reflux into the esophagus. BE is a premalignant condition associated with increased risk of esophageal cancer, especially esophageal adenocarcinoma. The Caudal-related homeodomain transcription factors Caudal-related homeodomain transcription factor CDX1 and CDX2 are expressed exclusively in the small and large intestine, playing important roles in proliferation and differentiation of intestinal epithelial cells. Ectopic expression of CDX1 and CDX2 occurs in BE. The apical sodium-dependent bile acid transporter (ASBT) is expressed primarily in terminal ileum where it is a key factor for intestinal reabsorption of bile salts. In addition to upregulation of CDX1 and CDX2, ASBT expression is up-regulated in BE. Furthermore, both CDX1/CDX2 and ASBT expressions are down-regulated in high-grade esophageal dysplasia. The alteration of the above-mentioned factors calls for attention: what is the relationship between CDXs and ASBT aberrant expression in BE? In this commentary, we discuss this issue on basis of the recent study done by Ma et al .

Changes of phasic and tonic smooth muscle function of jejunum in type 2 diabetic Goto-Kakizaki rats

AIM:To generate phasic and tonic stress-strain curves for evaluation of intestinal smooth muscle function in type 2 diabetic rats during active and passive conditions.METHODS:Seven diabetic Goto-Kakizaki(GK)male rats,32-wk old(GK group),and 9 age-matched normal Wistar rats(Normal group)were included in the study.Jejunal segments were distended up to a pressure of10 cm H2O in an organ bath containing 37℃Krebs solution with addition of carbachol(CA).The pressure and outer diameter changes were synchronously recorded.Passive conditions were obtained using calcium-free Krebs solution containing ethylene glycol tetraacetic acid and papaverine.Total phasic,tonic and passive circumferential stress and strain were computed from the diameter and pressure data with reference to the zero-stress state geometry.The active phasic and tonic stresses were defined as the total phasic and tonic stresses minus the passive stress.RESULTS:Diabetes increased jejunal mucosa and muscle layer thicknesses compared to the Normal group(mucosa,755.8±63.3 vs 633.1±59.1μm,P<0.01;muscle,106.3±12.9 vs 85.2±11.7μm,P<0.05).The pressure and stress thresholds were decreased in the GK group after CA application compared to distensions without CA application(pressure,1.01±0.07vs 1.99±0.19 cmH2O,P<0.01;stress,0.11±0.01vs 0.24±0.02 kPa,P<0.01).CA application did not change the pressure and stress threshold in the Normal group(pressure,2.13±0.32 vs 2.34±0.32 cm H2O,P>0.05;stress,0.25±0.03 vs 0.35±0.06 kPa,P>0.05).The amplitude of total phasic,total tonic,active phasic and active tonic circumferential stresses did not differ for the distensions without CA application between the GK group and the Normal group.However,the total phasic and total tonic stresses increased after CA application in the GK group compared those in the Normal group.When normalized to muscle layer thickness,the amplitude of active stresses before CA application was lowest in the GK group compared with the Normal group.No difference was found during CA application.CONCLUSION:The stress generated by intestinal muscle normalized to the muscle layer thickness was lowest in GK rats compared to normal rats whereas the response to CA stimulation was preserved.