| Malignant obstructive jaundice is a symptom which is caused by primary carcinoma of bile duct, ampullary, pancreas, hepar and metastatic lymph nodes of other position compressing bile duct. Because of the difficult of the early diagnosis and surgical removal, chemotherapy combine radiotherapy are recognized as the best palliative treatment. But severe jaundice is a major cause of death. ERBD which was invented in 70s of last century can effectively alleviate the symptoms of bile duct obstruction. ERBD is considered to be the minimum degree of trauma in patients with benign obstruction and the best choose for the malignant obstructive jaundice after more than 20 years of development. However, the most important issue after the stent placement is stent obstruction, simultaneous recurrent jaundice, and (or) cholangitis, making stents require frequent replacement. It not only affect the patient's life quality, but also increase economic burden. Therefore to investigate the reason and mechanism of the stent obstruction after ERBD, is becoming hotspot research in recent years. Radioactive Stents which is invented by our department is a special plastic bile stent combined radioactive seeds with stent drainage, which associate intervention and intraluminal brachytherapy (ILBT). It has advantage both in bile drainage and treatment of carcinoma. It improve the life quality of the patients notablely and establish new treatment method.Our previous animal study and clinical application demonstrated that radioactive stent appeared to be safe and potentially effective for the treatment of malignant obstructive jaundice which was unresectable. But the radioactive stent also has the problem about stent obstruction, and until now there isn't any corresponding research report investigating the possible mechanism of it. This study focus on the different obstructive components in radioactive stent and common plastic stent, to investigate the obstructive mechanism of radioactive stent.Objective1,To test the obstructive component in bile radioactive stent and common plastic stent, then analysis material compositions and discuss the different obstructive mechanism.2,According to the obstructive compositions of the two kinds of stents, to appraise the security and the efficiency of the radioactive stent.3,To do the groundwork for optimize the design of the radioactive stent, intend to prolong the patent time of the stent. MethodsFrom June 2008 to December 2009,20 occluded bile duct stents which were inserted by ERCP were retrieved from 20 malignant obstructive jaundice patients in the centre of endoscope of Changhai hospital. Radioactive stents which are 10Fr in group A(n=10), and the common plastic stents which are 10Fr and length between 9 to 15 cm producted by COOK in group B (n=10).1,A comparative study of microbiology All the samples were cut in three parts, and the segments were labeled as follows:(1) Upper segment:part closest to the liver, (2) Medium segment, (3) Lower segment:part closest to the duodenum. The three parts were analysed separately for microorganisms identification.2,A comparative study of physicochemical analysis(1) Scanning Electron MicroscopeThe scanning electron microscope was operated at 20kV. To investigate the different between the two kinds of stents according to the surface of internal and external stent amplifying in different multiples.(2) FTIR SpectroscopyDried the clogging material under vacuum for 12 hours and used the FTIR spectroscopy to analyses of the clogging material.(3) Pyrolysis derivatisation/gas chromatography/mass spectrometry (Py/GC-MS)The samples were deposited on a quartz capillary, The pyrolysis wire was set at 750℃. Pure commercially available bilirubin, cholesterol, palmitate were used as standards.(4) Histological studyThough the histological examination to determine their sources and composition of duct cleaning from ERCP.Results1,The result of bacterial culture and identification showed that, there were many kinds of bacteria and Fungi can cause the obstruction of the stents, such as escherichia coli, klebsiella pneumoniae, bacillus cloa, caebacillus proteus, acinetobacter baumannii, enterococcus faecalis, enterococcus faecium, pseudomonas aeruginosa, morganella morganii and chaplet. The bacteria's types and the quantity of types are not significant difference between the radioactive stent and the common stent (P>0.05).But the quantity of bacteria's types are significant in different part of the stent, the lower segments have more kinds of bacteria than other segments (P<0.05).2,According to the images of SEM, there are a layer like protein on the the most surfaces of external stents, but there are not on the common ones. Are basically consistent with the results of bacterial culture, there are bacterial biofilms on the surface of internal stents and there are a lot of bacilli and coccus in the stents. Meanwhile, cholesterol crystals and dietary fibers were seen by scanning electron microscope in the stents.3,The results of FTIR showed all the retrieved samples showed similar spectra, and the analysis of the clogging material showed that it mainly consists of calcium palmitate, bilirubinate, bilirubinate and protein. And the two characteristic peaks of the samples in view there is no significant difference.4,The results of PY/GC-MS showed split product formed by a variety of small molecules, molecular weight ranging between 120-400.The results from the Py/GC/MS analysis of the clogging material showed split product are bilirubinoid, palmitic acidsand, cholesterol. The sludge from different patients showed that the relative amount of each substance varied randomly between the patients.ConclusionThe low dose ofγ-rays released by 1251 radioactive seeds can not kill and inhibit the bacteria or this role is very weak; followed by the naked eye and scanning electron microscopy results suggest that in most samples of group A, the external surface of stents have more protein-like substances attached, those were reported in the literature, this layer of material with high protein content than in the stents. Therefore, we believe that protein content of the deposition in the external surface of radioactive stents are more than the common stents. This is due to internal exposure of radioactive particles cause necrosis of tumor cells, therefore, shedding sediment resulting from the stent lumen may one mechanism of the radioactive stents obstruction. But that, due to protein-like substance sediment, the radioactive stents may be easily obstructed than the common plastic stents. This result provide a favorable basis for improvement of the design of radioactive stent in the future.The results of FTIR and PY/GC-MS analysis showed that the clogging material were mainly consisted of calcium palmitate, bilirubinate, bilirubinate and protein.and composition had no significant differences between two groups(except not quantitative measurement of protein), other than quantitative is not outside), which further confirmed the safety of radioactive seeds stent. Histological results showed radioactive seeds to kill tumor cells resulting in the necrotic, confirming the effectiveness of radioactive stent. the results of this study comes from small samples, statistical findings from the reliability and availability is subject to verification of large sample tests, this study is ongoing at present, more accurate and satisfactory results will follow work display. |
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