Effects of cholesterol on the phenotype of rabbit bile duct fibroblasts

Local application of triamcinolone acetonide-conjugated chitosan membrane to prevent benign biliary stricture

Benign biliary stricture (BBS) is the proliferation of fibrous tissue of the biliary tract caused by the biliary operation, bile duct stones, cholangitis, trauma, and other etiologies due to scar contracture. Recent therapeutic strategies to suppress stenosis are insufficient. Here, we developed a sustained-release membrane (SM) of triamcinolone acetonide (TA) with N-succinyl hydroxypropyl chitosan (TASM) for inhibiting fibroblast proliferation in vitro and bile duct hyperplasia in the rabbit model for benign biliary stricture formation. The TASM were successfully placed in 45 of 50 rabbits. Evaluation of subcutaneous stimulation and acute liver injury confirms the safety of TASM in vivo. Compared to the control group, the TASM can significantly inhibit the proliferation of scar muscle fibroblasts in vitro. ELISA and immunofluorescence showed TASM could increase bFGF level and inhibit expression of TGFβ1 and αSMA. Cholangiographic and histologic examinations demonstrated significantly decreased tissue hyperplasia in the TASM groups compared with the model group. The immunohistochemical staining showed that TASM could reduce the level of cytokine-induced scars and inhibit the proliferation of myofibroblasts. Taken together, the chitosan membrane chemically conjugated with TA can effectively inhibit the benign biliary stricture. Further clinical usage of this membrane may effectively reduce the occurrence of benign biliary stricture.

Promoter cloning and characterization of the rabbit BK channel beta1 subunit gene

The beta1 subunit of the voltage-dependent and Ca(2+)-activated large-conductance K(+) channel (BK) in mammalian smooth muscle cells (SMCs) plays an important role in regulating smooth muscle tone and is closely linked with a series of smooth muscle tone associated diseases. However, knowledge of the transcriptional regulation of the BK beta1 is still largely unclear. For the first time, we cloned and characterized the full-length genomic sequence of the rabbit BK beta1 containing a 5'-flanking region of 2021 bp. The full-reading frame of the BK beta1 spans ~7.7 kb and is organized into 4 exons and 3 introns. All of the exon/intron junction sequences contain the GT/AG consensus junction sequence. The transcription initiation site (+1G) is located at 447 bp upstream of the translation initiation codon. Bioinformatics analysis indicated that, without any canonical TATA-box, the 5'-flanking region possesses a high GC content and contains a number of putative transcription factor binding sites. 5'-deletion analysis demonstrated that the region of -93/+30 potentially functions as a core promoter region. A gel mobility shift assay and chromatin immunoprecipitation assay revealed that Sp1 specifically interacts with a putative Sp1-binding site (-91/-85) in vitro and in vivo. Mutation of this site significantly diminished the promoter activities. Over-expression of Sp1 in smooth muscle cells of rabbit sphincter of Oddi enhanced the promoter activities of the BK beta1 in a dose-dependent manner. Thus, we suggest that the Sp1-binding site (-91/-85) is essential to the basal transcription of the rabbit BK beta1. Our studies provide a basic knowledge of the transcription regulation of the rabbit BK beta1.

The study between the dynamics and the X-ray anatomy and regularizing effect of gallbladder on bile duct sphincter of the dog

AIM: To study the relationship between the radiological anatomy and the dynamics on bile duct sphincter in bile draining and regulatory effect of gallbladder.

METHODS: Sixteen healthy dogs weighing 18 kg to 25 kg were divided randomly into control group and experimental group (cholecystectomy group). Cineradiography, manometry with perfusion, to effect of endogenous cholecystokinin and change of ultrastructure were employed.

RESULTS: According to finding of the choledochography and manometry, in control group the intraluminal basal pressure of cephalic cyclic smooth muscle of choledochal sphincter cCS was 9.0 ± 2.0 mmHg and that of middle oblique smooth muscle of choledochal sphincter (mOS) was 16.8 ± 0.5 mmHg, the intraluminal basal pressure of cCS segment was obviously lower than that of mOS (P < 0.01) in the interval period of bile draining, but significant difference of intraluminal basal pressure of the mOS segment was not found between the interval period of bile draining (16.8 ± 0.5 mmHg) and the bile flowing period (15.9 ± 0.9 mmHg) (P > 0.05). The motility of cCS was mainly characterized by rhythmically concentric contraction, just as motility of cCS bile juice was pumped into the mOS segment in control group. And motility of mOS segment showed mainly diastolic and systolic activity of autonomically longitudinal peristalsis. There was spasmodic state in cCS and mOS segment and reaction to endogenous cholecystokinin was debased after cholecystectomy. The change of ultrastructure of cCS portion showed mainly that the myofilaments of cell line in derangement and mitochondria is swelling.

CONCLUSION: During fasting, the cCS portion has a function as similar cardiac "pump" and it is main primary power source in bile draining, and mOS segment serves mainly as secondary power in bile draining. The existence of the intact gallbladder is one of the important factors in guaranteeing the functional coordination between the cCS and mOS of bile duct sphincter. There is dysfunction in the cCS and mOS with cholecystectomy.