Determination of Protein Binding of Troglitazone Stereoisomers by Fluorometric Titration

Determination of the protein binding of troglitazone is difficult because of its high adsorption to filters and membranes and the instability of the stereoisomers. We attempted to assess the protein binding of four stereoisomers of troglitazone in the plasma and albumin from several species by the method using fluorescent probes. The inhibition constants (K_i) for the stereoisomers of troglitazone were obtained from the decreases in fluorescence intensity of dansylsarcosine caused by competitive inhibition. Each stereoisomer of troglitazone displaced dansylsarcosine, a typical specific fluorescent probe for the diazepam binding site on human serum albumin (HSA). The highest binding affinity for dansylsarcosine was observed with HSA (dissociation constant, K_d,1 = 0·5 μM), while it was lowest in the mouse (K_d,1 = 18 μM). The K_i values for KK and ddY mouse plasma and mouse and rat albumin were in the range 2–15 μM, and there were no large variations among stereoisomers, the maximum differences being twofold. For human plasma and albumin, the displacement could not be accounted for by a simple competitive inhibition. Comparison between unbound fraction ( f_u) values calculated from thus obtained K_i values and those of a mixture of the four stereoisomers determined by high-performance frontal analysis showed that the f_u values obtained by fluorometric titration were higher, while the relative differences among the stereoisomers in terms of animal species and strain were comparable for the two methods. Small differences in protein binding among stereoisomers of troglitazone may not be the major reason for their stereoselective pharmacokinetics. © 1997 John Wiley & Sons, Ltd.     

Reduced expression of thrombopoietin is involved in thrombocytopenia in human and rat liver cirrhosis

It is widely accepted that thrombocytopenia associated with liver cirrhosis is caused by increased platelet destruction in the enlarged spleen, but this issue has not yet been analysed sufficiently in terms of platelet production. Thrombopoietin is produced mainly in the liver and strongly promotes platelet production. We studied serum thrombopoietin and the levels of its mRNA in liver tissue of cirrhotic patients and also in a rat model of liver cirrhosis. Furthermore, to clarify the influence of the spleen, we investigated thrombopoietin mRNA in splenectomized rats. The serum thrombopoietin level in humans with liver cirrhosis was not significantly reduced instead of thrombocytopenia. The expression of thrombopoietin mRNA in liver tissue decreased with the progression of liver cirrhosis in both patients and the rat model and no compensatory expression was observed in other organs or nonparenchymal cells. The level of thrombopoietin mRNA did not differ significantly in splenectomized cirrhotic rats before or after administration of dimethylnitrosamine, but was lower than that in splenectomized rats without cirrhosis. We conclude that thrombocytopenia in liver cirrhosis is caused not only by platelet destruction but also by decreased platelet production, perhaps due to reduction of thrombopoietin mRNA in the liver.     

Estimation of usefulness of N-butyl-2-cyanoacrylate-lipiodol mixture in transcatheter arterial embolization for urgent control of life-threatening massive bleeding from gastric or duodenal ulcer

We estimated the usefulness of a mixture of N-butyl-2-cyanoacrylate (NBCA) with lipiodol for transcatheter arterial embolization (TAE) used to control massive bleeding from gastric or duodenal ulcer. Thirty patients who had gastric or duodenal ulcers and massive bleeding that was uncontrollable by endoscopic procedures were included in this study. All patients were subjected to TAE (without NBCA in 23 and with NBCA in seven patients). Coils and/or gelfoam were also used. The achievement of haemostasis, occurrence of rebleeding and the time taken for TAE were compared between patients who received TAE without and with NBCA. Eighteen of 23 patients (78.3%) who received TAE without NBCA and six of seven patients (85.7%) who underwent TAE with NBCA achieved complete haemostasis without rebleeding. The time for TAE was significantly shorter in patients who received NBCA compared with those who did not (P= 0.0095). TAE using NBCA or a combination of NBCA and coils achieved a rapid, complete embolization regardless of vascular distribution or arterial diameter. Thus NBCA is considered to be useful as a secondary embolization material in TAE that is urgently conducted to control massive bleeding from gastric or duodenal ulcers.     

MMP-2及MMP-9表达在侵袭性垂体腺瘤中的生物学意义

目的本研究的目的是探讨基质金属蛋白酶-2(matrix metalloproteinase 2, MMP-2)及基质金属蛋白酶-9(matrix metalloproteinase 9, MMP-9)的表达与侵袭性垂体腺瘤相关性研究.以寻找垂体腺瘤侵袭性可能的发病机理.方法用免疫组化方法对54例垂体瘤患者的组织标本进行研究.并对其中16例患者采用逆转录-聚合酶链反应(RT-PCR)的方法对MMP-2及MMP-9 mRNA的表达进行分析.结果 54例垂体瘤患者中,有32例女性,22例男性.平均年龄为49.9岁(从18～76岁).其中,12例为侵袭性垂体腺瘤,42例为非侵袭性垂体腺瘤.免疫组化显示,侵袭性垂体腺瘤的MMP-2及MMP-9的表达明显高于非侵袭性垂体腺瘤(3.9±0.5; 2.3±0.2;P<0.01)和(4.1±0.4; 2.6±0.2; P<0.01).MMP-2及MMP-9的表达与MIB-1的表达无明显相关性(r=–0.05; P>0.05).侵袭性垂体腺瘤MMP-2及MMP-9 mRNA的表达,明显高于非侵袭性垂体腺瘤[(59.7±12.5)%; (33.3±5.4)%, P<0.05] 及[(68.2±15.3)%; (21.8±8.2)%; P<0.05] .结论 MMP-2及MMP-9的高表达与肿瘤的侵袭性密切相关.但与肿瘤的大小及分泌功能无明显关系.MMP-2及MMP-9可以作为肿瘤侵袭性一项有效的指标.肿瘤的侵袭性和增殖之间可能存在不同的生物学机制.     

Endoscopic Therapy of Early Gastric Cancer —Comparison of Endoscopic Mucosal Coagulation and Resection—

Abstract: The clinical efficacy of various methods of endoscopic treatment was evaluated in 70 patients with early gastric cancer. The treatments included using an Nd- YAG laser on 22 patients (2 IIa cases, 3 IIa + IIc cases and 17 IIc cases), a heater probe on 2 patients (IIc) and endoscopic mucosal resection (EMR) on 46 patients (13 I cases, 15 IIa cases, 2 IIa + IIc cases and 16 IIc cases). Laser irradiation and the heater probe method (endscopic mucosal coagulation; EMC), which cause coagulation and necrosis to lesions using heat energy, were found to be successful for well differentiated adenocarcinoma confined to the mucosa even if the size of the lesions was 20 mm and over. Poorly differentiated adenocarcinoma with lesions 20 mm or smaller reoccurred, and only well differentiated adenocarcinoma with infiltration limited to the mucosa seemed to be treatable endoscopically by EMR. Whether or not total resection was possible was determined with respect to the size and site of lesions in patients treated by EMR. Great therapeutic efficacy was achieved when the lesions were 10 mm or smaller and located in the anterior wall or the greater curvature. Piecemeal resection had to be made in a majority of cases when the lesions measured 10 mm or more or were located in the lesser curvature or the posterior wall. Therefore, endoscopic EMR is recommended if the size of the lesions is 10 mm or less, while EMC must also be considered if the lesions are larger or piecemeal resection is required.     

A pilot study to evaluate a new combination therapy for gastric ulcer: Helicobacter pylori eradication therapy followed by gastroprotective treatment with rebamipide

Background and Aim: Controversies remain over the need for antiulcer treatment following 1‐week eradication triple therapy for Helicobacter pylori‐positive peptic ulcers. The usefulness of combination therapy for gastric ulcers in Japanese patients, which consists of H. pylori eradication followed by gastroprotective therapy with rebamipide, was therefore evaluated. Methods: The study was conducted in 52 H. pylori‐positive patients with an endoscopically‐proven open gastric ulcer. All patients received 1‐week triple therapy (lansoprazole, amoxicillin and clarithromycin) followed by 7‐week rebamipide therapy. After completion of the combination therapy, all patients underwent evaluation of ulcer healing by endoscopy, gastric ulcer symptoms and H. pylori eradication by rapid urease test and ¹³C‐urea breath test. Results: The ulcer healing rates were 85.7% (36/42) at 8 weeks, 83.3% (30/36) in eradicated patients and 100% (6/6) in non‐eradicated patients. The overall gastrointestinal symptom‐free rate improved from 19.0% at baseline to 88.1% at 8 weeks. H. pylori was effectively eradicated in 85.7% (36/42) of patients. Conclusions: The results suggested that the combination therapy for open gastric ulcer was safe, well‐tolerated and effective. However, data from a double‐blind placebo‐controlled study is necessary to confirm these findings.