A study on the aggregation behavior of endotoxin molecules
| Autor: | Lin, Chen-Dar, 林建達 |
|---|---|
| Rok vydání: | 1993 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 81 Endotoxin為內毒素．其成分為革蘭陰氏菌(gram-negative)細胞壁上的多醣脂類，其強而有力的生化活性在動物體內外都是存在的．本研究主要目的在於探討內毒素在不同狀況下聚集的情形及大小分佈，以利後來過濾法和毒性測試之研究． 本研究首次採用了雷射光散射儀運用在測量內毒素的粒徑分佈上．發現內毒素經過超音波震盪後由雷射光散射儀測量有相當高的準確性．此可補足在電顯法和過濾法的缺點．光散射法可測得在改變PH值，溫度，離子強度等條件下，內毒素梓徑大小之變化．而實驗結果則顯示此變化在電顯法或過濾法中並無法明顯區分． 內毒素的大小會受藥品特性的影響而有所變化，如有二價陽離子Mg2+或Ca2+存在時，內毒素受到吸引形成較大的粒徑或是空腔狀的結構，經過超音波震盪後粒徑分佈範圍為30至110nm之間，粒徑平均值大約為50nm．有EDTA存在時，內毒素被分解形成一較小的粒徑．粒徑分佈範圍為 15至70nm之間，粒徑平均值大約為22nm．這些雷射光散射之結果都可由電子顯微鏡中得到定性之印證． 在毒性測試方面，內毒素粒徑平均大小介於30至50nm時，其粒徑分佈大約為20至110nm之間．注射入動物體內，發現發燒現象並未有顯著差異．亦即內毒素之毒性與其粒徑大小並未顯現直接之關連．故仍須朝使內毒素失活性化也或去除的方向努力. The purpose of this research is to study the aggregation behavior and particle size distribution of endotoxin in different aqueoussolutions. The component of endotoxin is lipopoiysaccharide(LPS) which is an integral part of the outer membrane of gram-negative bacteria. Due to its potent bioactivities, endotoxin is usually referred as an pyrogen. This is the first research to measure the particle size distribution of endotoxin by laser light scattering method. With ultrasonic pretreatment, this method shows very good precision. Therefore, it is applied to detect the small changes of the particle size distributions of endotoxin under different pH values, temperatures and ionic strengths. These changes can not be distinguished by the conventional electric microscopy and filtration methods. The particle size of endotoxin is affected by the chemical properties of solutions. For example, with Mg2+ or Ca2+ present, the endotoxin molecules aggregate to form a larger micell or a vesicle. Through ultrasonic pretreatment for 3 minutes the average particle size is about 50 nm. By contrast, endotoxin is decomposed into smaller particles in EDTA solutions. The particle sizes range from 15 to 70 nm and the average particle size is about 22 nm. These results are supported quantitatively by the pictures of electric microscopy. About the toxicity test, endotoxin solutions of different particle sizes are used to inject into rabbits. The range of average particle size is between 30 and 50 nm and its particle size distribution is from 20 to 110 nm. From the resuits, we find that there is no significant difference about its pyrogenetic ability and there is no direct correlation between the particle size and the endotoxin toxicity. |
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