Effect of a protein binding change on unbound and total plasma concentrations for drugs of intermediate hepatic extraction

For substances eliminated from blood by the liver, the effect of a change in unbound fraction of drug (fu _b )on steady state total (C _b )and unbound (Cu _b )blood concentrations has hitherto only been considered for the two limiting cases, i.e., at the upper and lower extremes of hepatic intrinsic clearance (CL _int ).For a substance of very low CL _int ,if fu _b changes, C _t will change and Cu _b will remain constant, whereas if CL _int isvery high, Cu _b will change and C _b will remain constant.The present study defines the effects of a change in fu _b on C _b and Cu _b over the whole CL _int range. Computer simulations were undertaken which predicted that, for a given change in fu _b ,absolute and relative changes in C _b would decreasenonlinearly with increasing CL _{int, twhile the relative change in} Cu _{b would} increasewith CL _int .The absolute change in Cu_b would be independent of CL _int .Significant changes in C_b and Cu _{b would be observed at intermediate values of} CL _{int not just at the high and low extremes. These theoretical predictions were investigated experimentally in the isolated perfused rat liver by examining the effects of a change in} fu _{b of sodium taurocholate a substance with intermediate} CL _int (such that at fu _b =0.27,hepatic extraction ratio=0.71) induced by concurrent administration of sodium oleate. Sodium 24- ¹⁴ C-taurocholate (specific activity 52 Ci/mmol) was infused into the reservoir in a recycling system at 30 mol/hr for 105 min (n=6). At 45 min a bolus dose of sodium oleate (50 mmol) was administered to the reservoir, followed by a constant infusion of 143 mmol/hr for 1 hr. Following the administration of oleate, taurocholate fu _{b fell promptly by 55% (0.27–0.12). There was a relative increase of taurocholate} C _{b of 22.7% and a relative decrease in} Cu _{b of 45.4%, in accordance with the simulations (p<0.05). We conclude that important changes in unbound steady-state concentration, the pharmacologically active moiety, can occur upon changes in unbound fraction with compounds of intermediate hepatic intrinsic clearance}.This study was supported by the National Health and Medical Research Council of Australia.     

卡介苗多糖核酸微乳的研究

目的制备卡介苗多糖核酸(BCG-PSN)微乳。方法采用磷脂为乳化剂,乙醇为助乳化剂,油酸乙酯为油相,用改良三角相图法确定微乳区域,优化BCG-PSN微乳处方组成。结果与结论所制得BCG-PSN微乳澄清透明,性质稳定。     

Reduction in Insulin Mediated ERK Phosphorylation by Palmitate in Liver Cells Is Independent of Fatty Acid Induced ER Stress

Saturated free fatty acids (FFAs) such as palmitate in the circulation are known to cause endoplasmic reticulum (ER) stress and insulin resistance in peripheral tissues. In addition to protein kinase B (AKT) signaling, extracellular signal-regulated kinase (ERK) has been implicated in the development of insulin resistance. However, there are conflicting data regarding role of ERK signaling in ER stress-induced insulin resistance. In this study, we investigated the effects of ER stress on insulin resistance and ERK phosphorylation in Huh-7 cells and evaluated how oleate prevents palmitate-mediated ER stress. Treatment with insulin resulted in an increase of 38–45% in the uptake of glucose in control cells compared to non-insulin-treated control cells, along with an increase in the phosphorylation of AKT and ERK. We found that treatment with palmitate increased the expression of ER stress genes, including the splicing of X box binding protein 1 (XBP1) mRNA. At the same time, we observed a decrease in insulin-mediated uptake of glucose and ERK phosphorylation in Huh-7 cells, without any change in AKT phosphorylation. Supplementation of oleate along with palmitate mitigated the palmitate-induced ER stress but did not affect insulin-mediated glucose uptake or ERK phosphorylation. The findings of this study suggest that palmitate reduces insulin-mediated ERK phosphorylation in liver cells and this effect is independent of fatty-acid-induced ER stress.     

Sodium oleate induced rapid gelation of silk fibroin

Silk fibroin has acquired increasing interest in the last years for application in medicine and namely in tissue engineering. Several methods have been developed to process fibroin and for the fabrication of nets, sponges, films and gels. This paper deals with the fabrication and characterization of fibroin hydrogels obtained by using sodium oleate as gelation agent. Gels have been prepared by mixing Silk fibroin (SF) and Sodium oleate (SO) water solutions in different concentrations, and a quite wide frame of compositions have been explored. Rheological tests have been performed to determine the gelation times, scanning electron microscopies have been made to evaluate morphologies, FTIR analysis has been done to determine the conformation of the starting materials and of the resulting gels, water content has been measured and cytotoxicity tests have been performed to validate the potential biomedical use of the hydrogels. Depending on the SF and SO different gelation times have been obtained thanks to the formation of intermolecular bonds between the fibroin chains. The obtained fastest gelation of about 80 s could make this specific formulation compatible with in situ gelation. By changing composition, gels with different morphologies, rheological properties and water contents have been prepared.     

Evaluation of endoscopic variceal ligation in prophylactic therapy for bleeding of oesophageal varices: a prospective, controlled trial compared with endoscopic injection sclerotherapy

BACKGROUND: To evaluate the efficacy of endoscopic variceal ligation (EVL) in prophylactic therapy for oesophageal varices, we performed a randomized prospective trial to compare the recurrence of oesophageal varices treated by EVL with those treated by endoscopic injection sclerotherapy. METHODS: Fifty patients with liver cirrhosis were divided into two groups at random, after informed consents were obtained, to receive prophylactic therapy for bleeding of oesophageal varices. Group 1 patients underwent sessions of sclerotherapy with 5% ethanolamine oleate used as the sclerosant. Group 2 patients underwent EVL followed by one or two sessions of sclerotherapy. RESULTS: During the 18 month follow-up period, both the recurrence rate in group 2 (56%) and the incidence of bleeding (20%) were significantly higher compared with group 1 (recurrence rate 16%, bleeding 0%). CONCLUSIONS: This result indicates that EVL is not effective for prophylactic therapy for oesophageal varices in liver cirrhosis.     

化学促渗剂与负极性驻极体促进5-氟尿嘧啶体外透过大鼠增生性瘢痕和背部皮肤的比较

目的 比较化学促渗剂和负极性驻极体对5-氟尿嘧啶（5-FU）体外经增生性瘢痕皮肤的促渗作用,为驻极体5-FU缓控释贴剂的制备奠定基础。方法 通过Franz扩散池和高效液相色谱仪,研究1%氮酮、10%油酸乙酯、-1 000 V驻极体、-1 500 V驻极体和-2 000 V驻极体作用后5-FU的体外经大鼠瘢痕皮肤或背部皮肤的透皮规律。结果 （1）1%氮酮和10%油酸乙酯均可促进5-FU经大鼠瘢痕皮肤的渗透,且10%油酸乙酯的促渗效果优于1%氮酮。（2）化学促渗剂作用下的5-FU经大鼠瘢痕皮肤和背部皮肤的体外渗透规律相似,但是5-FU经瘢痕皮肤的累积透皮量少于经背部皮肤的累积透皮量。（3）负极性驻极体对5-FU均具有良好的促渗作用,促渗效果的优劣顺序依次为：-2 000 V驻极体、-1 500 V驻极体、-1 000 V驻极体。同样,负极性驻极体作用下5-FU经大鼠瘢痕皮肤的累积透过量少于经背部皮肤的累积透皮量。结论 化学促渗剂和负极性驻极体均能促进5-FU的经皮渗透。其中,10%油酸乙酯和-2 000 V驻极体对5-FU的促渗效果最佳,可用于驻极体5-FU缓控释贴剂的制备。     

Palmitate-induced Activation of Mitochondrial Metabolism Promotes Oxidative Stress and Apoptosis in H4IIEC3 Rat Hepatocytes

Objective

Hepatic lipotoxicity is characterized by reactive oxygen species (ROS) accumulation, mitochondrial dysfunction, and excessive apoptosis, but the precise sequence of biochemical events leading to oxidative damage and cell death remains unclear. The goal of this study was to delineate the role of mitochondrial metabolism in mediating hepatocyte lipotoxicity.

Materials/Methods

We treated H4IIEC3 rat hepatoma cells with free fatty acids in combination with antioxidants and mitochondrial inhibitors designed to block key events in the progression toward apoptosis. We then applied ¹³C metabolic flux analysis (MFA) to quantify mitochondrial pathway alterations associated with these treatments.

Results

Treatment with palmitate alone led to a doubling in oxygen uptake rate and in most mitochondrial fluxes. Supplementing culture media with the antioxidant N-acetyl-cysteine (NAC) reduced ROS accumulation and caspase activation and partially restored cell viability. However, ¹³C MFA revealed that treatment with NAC did not normalize palmitate-induced metabolic alterations, indicating that neither elevated ROS nor downstream apoptotic events contributed to mitochondrial activation. To directly limit mitochondrial metabolism, the complex I inhibitor phenformin was added to cells treated with palmitate. Phenformin addition eliminated abnormal ROS accumulation, prevented the appearance of apoptotic markers, and normalized mitochondrial carbon flow. Further studies revealed that glutamine provided the primary fuel for elevated mitochondrial metabolism in the presence of palmitate, rather than fatty acid beta-oxidation, and that glutamine consumption could be reduced through co-treatment with phenformin but not NAC.

Conclusion

Our results indicate that ROS accumulation in palmitate-treated H4IIEC3 cells occurs downstream of altered mitochondrial oxidative metabolism, which is independent of beta-oxidation and precedes apoptosis initiation.     

ANALYSIS OF PROGNOSTIC FACTORS IN PATIENTS WITH GASTRIC VARICES AFTER ENDOSCOPIC TREATMENT

Background: The prognostic factors, including gastric variceal bleeding itself, in patients with gastric varices (GV) after endoscopic treatment remain unclear. The aim of this study was to analyze prognostic factors in patients with GV after endoscopic treatment as well as to evaluate safety and efficacy of our endoscopic treatment. Patients and Methods: This study enrolled 115 patients who underwent endoscopic treatment for GV between October 1988 and December 2003 using cyanoacrylate and 5% ethanolamine oleate. Successful hemostasis, recurrence rates, rebleeding rates, survival rates, complications and prognostic factors after the treatment were retrospectively reviewed. Results: Treatment sessions for GV were performed 3.4 ± 2.5 times. All cases, including 14 emergency cases, were treated successfully. The cumulative recurrence rates at 1, 3 and 5 years after the treatment were 7.0%, 15.6% and 20.0%, respectively, and the cumulative rebleeding rates at 1, 3 and 5 years were 3.5%, 8.7% and 14.8%, respectively. The overall survival rates were 78.3%, 63.7% and 51.5% at 1, 3 and 5 years, respectively. Grade B or C in Child–Pugh classification, emergency or elective cases, and association with hepatocellular carcinoma were identified as significant negative prognostic factors after endoscopic treatment by multivariate analysis. Although several complications were observed, there was no mortality. Conclusions: Grade B or C in Child–Pugh classification, emergency or elective situation, and association with hepatocellular carcinoma are negative prognostic factors after endoscopic treatment.     

Inhibitive effects of glucose and free fatty acids on proliferation of human vascular endothelial cells in vitro

Objectives To investigate the effects of glucose and free fatty acids (FFAs) on the proliferation and cell cycle of human vascular endothelial cells in vitro , and to examine whether the combined presence of elevated FFAs and glucose may cross-amplify their individual injurious effects.Methods Cultured human vascular endothelial cells (ECV304) were incubated with various concentrations of glucose and/or FFAs (palmitate and/or oleate) for 24-96 h. Morphologic alterations were observed using a phase contrast microscope and an electron microscope. Inhibition of proliferation was measured by a colorimetric 3-［4, 5-dimethyl thiazol-2-yl］-2, 5-diphenyltetrazolium bromide (MTT) assay. Cell viability was determined using trypan blue exclusion. Distribution of cells along phases of the cell cycle was analyzed by flow cytometry. Results Glucose 15 or 30 mmol/L, palmitate (PA) 0.25 or 0.5 mmol/L, and oleate (OA) 0.5 mmol/L inhibited proliferation and accelerated death of endothelial cells in a dose-and-time-dependent manner. After treatment with elevated glucose and/or FFAs, the G(0)/G(1) phase cells increased, whereas S phase cells decreased, suggesting that high glucose and/or FFAs mainly arrested endothelial cells at G(0)/G(1) phase. The inhibitive rates of proliferation and population of dead cells in endothelial cells incubated with glucose plus FFAs (glucose 30 mmol/L+PA 0.25 mmol/L, glucose 30 mmol/L+OA 0.5 mmol/L, glucose 30 mmol/L+PA 0.25 mmol/L+OA 0.5 mmol/L) increased more markedly than those treated with high glucose or FFAs (PA and/or OA) alone. Conclusion Both high ambient glucose and FFAs can inhibit proliferation and accelerate death of endothelial cells in vitro. These changes were cross-amplified in the combined presence of high levels of glucose and FFAs.     

Sclerotherapy for Simple Cysts with Use of Ethanolamine Oleate: Preliminary Experience

We evaluated the efficacy of ethanolamine oleate (EO) as a sclerosing agent for a symptomatic hepatic or renal cyst. Seven patients with symptomatic hepatic (n = 3) or renal cysts (n = 4) were treated by sclerotherapy with EO. The cyst size in the greater diameter ranged from 6 to 13 cm. The cyst was punctured under ultrasound guidance, and after all of the cyst’s content was aspirated, an iodized contrast agent was injected to check the absence of communication between the cyst and biliary tree, urinary tract, or vessels. Then, the solution of ethanolamine oleate–iopamidol mixture (EOI) of 10% of the volume of the cyst’s content was injected via catheter. After 30 min, the injected EOI was aspirated completely before catheter removal. A follow-up computed tomography scan was performed at 1 and 3 months after treatment. The volume of the cyst and its reduction rate was calculated. In addition, symptoms and complications were assessed. The volume of the cyst ranged from 64 to 636 ml (mean: 328 ml) before treatment. Three months after treatment, it ranged from 2 to 50 ml (mean: 15ml) and the reduction rate of the cyst’s volume was more than 90% on average. Symptoms caused by the cyst disappeared in all cases and no major complication was encountered. Although two patients had a low-grade fever after sclerotherapy, it was easily controlled. It is suggested that the sclerotherapy with EO might be a safe, effective, well-tolerated treatment for symptomatic hepatic or renal cysts.