Impact of Light Shielding on Photo-Degradation of Dacarbazine during the Preparation Process.

Dacarbazine (DTIC) is converted to the photo-degradation product 4-diazoimidazole-5-carboxamide (Diazo-IC) by light. Diazo-IC production is often responsible for the pain reactions observed during peripheral intravenous infusion of DTIC in clinical settings. Although light shielding during infusion decreases the photo-degradation of DTIC, its usefulness for the preparation of DTIC has not yet been fully clarified. The aim of this study was to investigate the light conditions during the preparation of DTIC solution in the compounding room from the viewpoint of the production amount of Diazo-IC. DTIC solution was prepared in the compounding room. Various light and temperature conditions and dissolving solutions during the preparation were investigated. The amounts of DTIC and Diazo-IC in solutions were determined using an HPLC coupled to UV detection. The photo-degradation of DTIC was estimated by the amount of Diazo-IC. Diazo-IC production in the dissolving solutions increased in a time-dependent manner at 4 and 25°C under light shielding. Light exposure during the dissolving process did not affect the DTIC and Diazo-IC concentrations. Light shielding during dissolution did not alter the Diazo-IC production until 4 h after dilution. In conclusion, short duration light exposure did not affect Diazo-IC production. These findings suggest that light shielding is not needed in the preparation of DTIC in the compounding room from the viewpoint of Diazo-IC production.

Large balloon dilation for the treatment of recurrent bile duct stones prevents short-term recurrence in patients with previous endoscopic sphincterotomy.

BACKGROUND/PURPOSE: Our previous study revealed the efficacy and safety of the large balloon dilation (LBD) technique. However, there is insufficient objective data about the recurrence rate. The aim of this study was to compare the recurrence rate of common bile duct (CBD) stones between patients treated with and without LBD. METHODS: Patients with recurrent CBD stones treated between April 2006 and August 2010, and who had a history of endoscopic sphincterotomy (ES), were enrolled. Patients were excluded if they had a CBD diameter of less than 10 mm or if the diameter of their largest CBD stone was <10 mm. RESULTS: A total of 62 consecutive patients were investigated. From April 2006 to November 2007, 32 patients were treated without LBD (non-LBD group; historical control). From December 2007 to August 2010, 30 patients underwent LBD (LBD group). The median follow-up times in the LBD and non-LBD groups were 517 and 1034 days (p < 0.001), respectively. Kaplan-Meier analysis revealed a significantly lower incidence of recurrent CBD stones in the LBD group than in the non-LBD group (p = 0.048). CONCLUSIONS: LBD reduces the short-term recurrence of CBD stones in patients with previous ES.

Safety and long-term outcomes of endoscopic papillary balloon dilation in children with bile duct stones.

BACKGROUND: Although experience with diagnostic and therapeutic ERCP in children is growing, little is known about the safety and technical outcomes of endoscopic papillary balloon dilation (EPBD) in pediatric patients with bile duct stones (BDSs). OBJECTIVE: To assess the safety and long-term outcomes of EPBD in pediatric patients with BDSs. DESIGN: Case study. SETTING: Tertiary referral center. PATIENTS AND INTERVENTIONS: This study involved 5 children who had BDSs combined with gallstones who underwent EPBD. MAIN OUTCOME MEASUREMENTS: Successful EPBD, successful stone removal, procedure-related complications, and long-term outcomes. RESULTS: ERCP was successful in all cases, with cannulation and subsequent EPBD. Stone removal was performed in 1 session in all patients. No EPBD-related complications were observed in any patient. After EPBD, 1 patient subsequently underwent laparoscopic cholecystectomy for gallstones. The remaining 4 were followed without surgery. In 2 patients, gallstones were spontaneously passed from the bile duct into the duodenum. During the follow-up period, over a mean of 7.1 years (range 3.7-9.3 years), no recurrence of BDSs was observed in any patient. LIMITATIONS: Small number of patients. CONCLUSIONS: Although BDSs are rare in pediatric patients, EPBD may be a safe and effective technique for the management of such stones in some children.

Lipid rafts serve as signaling platforms for Tie2 receptor tyrosine kinase in vascular endothelial cells.

The Tie2 receptor tyrosine kinase plays a pivotal role in vascular and hematopoietic development. The major intracellular signaling systems activated by Tie2 in response to Angiopoietin-1 (Ang1) include the Akt and Erk1/2 pathways. Here, we investigated the role of cholesterol-rich plasma membrane microdomains (lipid rafts) in Tie2 regulation. Tie2 could not be detected in the lipid raft fraction of human umbilical vein endothelial cells (HUVECs) unless they were first stimulated with Ang1. After stimulation, a minor fraction of Tie2 associated tightly with the lipid rafts. Treatment of HUVECs with the lipid raft disrupting agent methyl-beta-cyclodextrin selectively inhibited Ang1-induced Akt phosphorylation, but not Erk1/2 phosphorylation. It has been reported that inhibition of FoxO activity is an important mechanism for Ang1-stimulated Tie2-mediated endothelial function. Consistent with this, we found that phosphorylation of FoxO mediated by Tie2 activation was attenuated by lipid raft disruption. Therefore, we propose that lipid rafts serve as signaling platforms for Tie2 receptor tyrosine kinase in vascular endothelial cells, especially for the Akt pathway.

Involvement of MDR1 function in proliferation of tumour cells.

Mdr1 is a multi-drug-resistance protein, a member of the adenosine triphosphate-binding cassette family of drug transporters. Mdr1 is expressed in wide variety of cells and limits absorption of toxicants into the body or tissue; however, it is also expressed in many cancer cells and can render tumour cells resistant to many anti-cancer drugs. Mdr1 is well studied as a multi-drug resistance transporter, but little is known regarding its other role in tumour cells. In the present study, we investigated mdr1 function in tumour cell proliferation. We silenced the mdr1 gene in tumour cells by using an RNA interference method that employed short hairpin RNA. The result showed that knockdown of mdr1 gene suppressed tumour cell proliferation in vitro, and induced the passage of the cell cycle into the G1/G0 phase. Furthermore, in a mice xenograft tumour formation assay, mdr1 knockdown of tumour cells inhibited tumour expansion. These results suggest that Mdr1 plays a role in regulation of tumour cells proliferation.

EphB4 overexpression in B16 melanoma cells affects arterial-venous patterning in tumor angiogenesis.

EphB4 receptor and its ligand ephrinB2 play an important role in vascular development during embryogenesis. In blood vessels, ephrinB2 is expressed in arterial endothelial cells (EC) and mesenchymal supporting cells, whereas EphB4 is only expressed in venous ECs. Previously, we reported that OP9 stromal cells, which support the development of both arterial and venous ECs, in which EphB4 was overexpressed, could inhibit ephrinB2-positive (ephrinB2+) EC development in an embryonic tissue organ culture system. Although the EphB4 receptor is expressed in a variety of tumor cells, its exact function in regulating tumor progression has not been clearly shown. Here we found that overexpression of EphB4 in B16 melanoma cells suppressed tumor growth in a s.c. transplantation tumor model. Histologic examination of these tumors revealed that EphB4 overexpression in B16 cells selectively suppressed arterial ephrinB2+ EC development. By coculturing ephrinB2-expressing SV40-transformed mouse ECs (SVEC) with EphB4-overexpressing B16 cells, we found that EphB4 induced the apoptosis of SVECs. However, ephrinB2 did not induce the apoptosis of EphB4-overexpressing B16 cells. Based on results from these experiments, we concluded that EphB4 overexpression in B16 tumor cells suppresses the survival of arterial ECs in tumors by a reverse signaling via ephrinB2.