首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 125 毫秒
1.
本试验旨在制备玫瑰总黄酮脂质体(RTF-L),优化其处方,并对其质量进行评价。以薄膜-超声分散法制备RTF-L,采用超速离心-紫外分光光度法测定其包封率,以包封率为主要考察指标,采用正交试验优化其处方,并通过最优处方下制备的RTF-L的外观形态、粒径、粒度分布(PDI)、Zeta电位、体外累积释放率等评价其性质。结果显示,制备RTF-L的最佳处方为磷脂浓度0.3%,药物与磷脂比1∶15,水相介质pH 6.5,胆固醇与磷脂比1∶2;所制得的RTF-L包封率为(77.0±0.2)%,粒径为(155.40±2.11)nm, Zeta电位为(-21.03±1.24)mV,PDI为0.035±0.003,稳定性良好;体外累积释放试验结果显示,玫瑰总黄酮(RTF)溶液在6 h累积释放率为85.15%,基本释放完全,而RTF-L在6 h累积释放率为76.42%,与原药相比有一定的缓释作用。结果表明,优选处方稳定可行,所制备的RTF-L包封率高,粒径小且均匀,为RTF的进一步开发利用及其新剂型的研发提供一定的参考依据。  相似文献   

2.
旨在制备并表征沙拉沙星/β-环糊精（SAR/β-CD）包合物微囊新制剂,测定增溶倍数和包封率,进行SAR/β-CD包合物微囊的体外溶出与体内药代动力学研究。采用搅拌法制备包合物微胶囊,用透射电镜、扫描电镜和粉末X光衍射技术进行物态表征。采用液相色谱法测定SAR/β-CD包合物微囊的增溶倍数和包封率,通过溶出试验研究SAR/β-CD包合物微囊在磷酸盐缓冲液（pH6.8）中的释放规律。最后,进行了环糊精包合物微囊在鸡体内的药代动力学评价。理化表征试验证明,药物进入β-环糊精空腔,成功获得了SAR/β-CD包合物微囊。3个试验批次的SAR/β-CD包合物微囊的平均增溶倍数和平均包封率分别为（25.3±1.15）倍和90.3%±0.15%。在磷酸盐缓冲液（pH6.8）中SAR/β-CD包合物微囊的溶出率为95.6%,而普通粉剂的溶出率仅为72.2%,包合反应后的制剂溶解度和溶出度均有显著提高。药代动力学试验中血药浓度检测的标准曲线为y=1.563 2x-0.189 6,R2=0.999 3,在0.25~10.00 μg·mL-1内呈良好的线性关系。分析方法的精密度RSD值小于10%,分析方法的准确度大于90%,同时小于110%;回收率试验表明,低浓度（0.50 μg·mL-1）回收率为90.55%±3.81%,中浓度（1.00 μg·mL-1）回收率为93.85%±3.14%,高浓度（2.50 μg·mL-1）回收率为98.19%±5.41%。冻融试验表明冻融稳定性（n=3）符合《中华人民共和国兽药典》（2015版）规定。鸡口服药代动力学试验表明,SAR/β-CD包合物微囊和沙拉沙星粉的AUC（mg·h-1·L-1）、Tmax（h）、Cmax（μg·mL-1）分别为43.59±0.50、2.18±0.09、5.99±0.30和17.27±0.30、0.98±0.07、1.19±0.10。成功制备沙拉沙星/β-环糊精包合物微囊新剂型,明显提高了药物的溶出率和生物利用度,对喹诺酮类药物的推广应用具有重要意义。  相似文献   

3.
用聚乳酸羟基乙酸共聚物（PLGA）将鸡堆型艾美耳球虫重组表达质粒pcDNA3.1-3-1E包封,采用水包油包水（W/O/W）双重乳化方法制备pcDNA3-3-1E/PLGA微球。通过正交试验设计优化PLGA微球制备工艺,考察PLGA浓度、聚乙烯醇（PVA）浓度、超声功率、复乳搅拌时间对评价指标（即微球粒径大小、包封率、载药量）的影响,确定制备微球的最佳工艺条件。测定微球的形态、粒径、完整性、质粒DNA包封率、载药量和释放程度;进行体外模拟鸡胃液和肠液试验,观察微球体外释药效果。结果显示,当PLGA浓度为8%、PVA浓度为1.5%、超声功率为60W、复乳搅拌6h为微球制备的最佳工艺参数,在光镜下呈散在圆形,粒径小于12μm。微球的包封率、载药量分别为84.25%和4.46%,裸质粒与微球中质粒超螺旋比例差距不显著,这表明在包被过程中的超螺旋质粒未发生明显的降解。在模拟鸡的胃肠液累积释放试验中,它的累积释放能力依次为pH 3.0〉pH 7.4,载药微球在模拟鸡的胃肠液中24h释放26.8%,模拟肠液中24h释放11.2%,30d时体外累积释放率为81.7%,表明微球具有一定的缓释效果。  相似文献   

4.
磷酸泰乐菌素脂质体的制备及体外释放动力学研究   总被引：2，自引：2，他引：0  
主编 《中国兽药杂志》2010,44(10):24-28
为延长磷酸泰乐菌素在体内的作用时间,通过比较采用硫酸铵梯度法制备其脂质体制剂。以包封率为指标,分别考察磷脂与胆固醇之比、药脂比、硫酸铵浓度、孵化温度和孵化时间对包封率的影响,并在此基础上进行正交试验筛选最优处方。同时,对所得脂质体的形态、粒径及分布、包封率及体外释放动力学进行研究。结果显示,正交试验优化得到的最佳处方工艺如下,磷脂与胆固醇质量比为4∶1,药脂比为1∶10,硫酸铵浓度为300 mmol/L,体系pH值为7.0,孵化温度为50℃,孵化时间为20 m in。电镜下观察脂质体呈球形或类球形,分布均匀,平均粒径为6.526μm,且大部分在1μm~12μm之间,包封率为58.32%,体外释药符合W eibull方程(r=0.976 4)。研究证实硫酸铵梯度法制备磷酸泰乐菌素脂质体方法可行,包封率高,稳定性好,体外释药具有一定的缓释效应。  相似文献   

5.
目的:研究纳米蜂胶的体外药剂学性质。方法:采用β-环糊精包埋制备纳米蜂胶,检验其载药量、包封率和粒径,考察其体外释放度。结果:纳米蜂胶包封率达到98%以上,平均粒径为210nm,体外释放24h达68%。结论:所制得的纳米蜂胶的理化性质优良,具有缓释效应。  相似文献   

6.
《中国兽医学报》2017,(1):92-96
为了屏蔽药物的不良味道,本试验以聚丙烯酸树脂IV为囊材,采用液中干燥法制备了氧氟沙星掩味微囊。试验以包封率及载药量为指标,通过考察溶剂、囊材、乳化剂、抗黏剂的用量对微囊的影响来筛选处方工艺。应用最佳工艺制备的氧氟沙星掩味微囊,载药量为57.4%,包封率为48.6%。该微囊在模拟口腔环境(pH值为7.0)介质中释放极其缓慢,60min仅释放总药量的2.1%;随着释放介质的酸度提高,药物的释放速率显著加快;除此之外,在胃酸酸度(pH值为1.0~3.0)范围内,氧氟沙星的释放还呈现缓释特征,可持续近10h。体外试验显示,采用液中干燥法制备得的氧氟沙星微囊,既可掩味又能实现持续释药,而且制备工艺简便,具有很好的应用前景。  相似文献   

7.
旨在制备并表征沙拉沙星/β-环糊精(SAR/β-CD)包合物微囊新制剂,测定增溶倍数和包封率,进行SAR/β-CD包合物微囊的体外溶出与体内药代动力学研究。采用搅拌法制备包合物微胶囊,用透射电镜、扫描电镜和粉末X光衍射技术进行物态表征。采用液相色谱法测定SAR/β-CD包合物微囊的增溶倍数和包封率,通过溶出试验研究SAR/β-CD包合物微囊在磷酸盐缓冲液(pH6.8)中的释放规律。最后,进行了环糊精包合物微囊在鸡体内的药代动力学评价。理化表征试验证明,药物进入β-环糊精空腔,成功获得了SAR/β-CD包合物微囊。3个试验批次的SAR/β-CD包合物微囊的平均增溶倍数和平均包封率分别为(25.3±1.15)倍和90.3%±0.15%。在磷酸盐缓冲液(pH6.8)中SAR/β-CD包合物微囊的溶出率为95.6%,而普通粉剂的溶出率仅为72.2%,包合反应后的制剂溶解度和溶出度均有显著提高。药代动力学试验中血药浓度检测的标准曲线为y=1.563 2x-0.189 6,R~2=0.999 3,在0.25～10.00μg·mL~(-1)内呈良好的线性关系。分析方法的精密度RSD值小于10%,分析方法的准确度大于90%,同时小于110%;回收率试验表明,低浓度(0.50μg·mL~(-1))回收率为90.55%±3.81%,中浓度(1.00μg·mL~(-1))回收率为93.85%±3.14%,高浓度(2.50μg·mL~(-1))回收率为98.19%±5.41%。冻融试验表明冻融稳定性(n=3)符合《中华人民共和国兽药典》(2015版)规定。鸡口服药代动力学试验表明,SAR/β-CD包合物微囊和沙拉沙星粉的AUC(mg·h~(-1)·L~(-1))、T_(max)(h)、C_(max)(μg·mL~(-1))分别为43.59±0.50、2.18±0.09、5.99±0.30和17.27±0.30、0.98±0.07、1.19±0.10。成功制备沙拉沙星/β-环糊精包合物微囊新剂型,明显提高了药物的溶出率和生物利用度,对喹诺酮类药物的推广应用具有重要意义。  相似文献   

8.
本试验旨在制备黄体酮聚乳酸微球,并考察其体外释药性能。以包封率、载药量为主要评价指标,考察制备黄体酮微球的主要影响因素,筛选出最佳工艺条件。扫描电子显微镜观察微球形态,紫外—可见分光光度法测定微球的包封率、载药量和体外释药特性。最佳工艺所制备的微球光滑、圆整、均匀、分散性好,包封率为(80.60±1.00)%,载药量为(10.63±0.05)%,在7 d内累积释药率达53.41%。制备微球包封率和载药量高,具有明显的缓释效果,能有效地延长药物作用时间。  相似文献   

9.
为了解聚乳酸-羟基乙酸共聚物(PLGA)微球在体内外环境中形态的差异，进一步解析PLGA微球体内外环境对药物释放的影响，本试验采用乳化法制备PLGA微球，荧光标记后，采用光学显微镜、荧光分光光度计、激光共聚焦显微镜和苏木精-伊红染色法分别观察PLGA微球在不同介质、体外细胞环境和小鼠体内环境中形态的变化。结果显示，制备的PLGA微球为透明且表面光滑的球形，在水、PBS和血清中保持球形，膨胀率分别为23.7%、13.1%和0.5%;在0、24、48和72 h时，PLGA微球在血清中泄露分别是PBS中的6.54倍、8.66倍、4.67倍和3.61倍；PLGA微球在体外细胞环境中为半透明球形；PLGA微球在小鼠体内环境条件下前2天保持球形，第3天PLGA微球的形态发生变化。PLGA微球表面和内部结构在体外和体内环境中的差异表明PLGA微球中的药物在体外和体内环境中释放也存在差异。本试验发现体外和体内环境条件下PLGA微球形态会发生变化，可作为合理设计静脉注射用PLGA微球的参考，为进一步改善PLGA微球中药物释放提供数据支持。  相似文献   

10.
市售伊维菌素制剂存在生物利用度低,释药峰谷浓度差异大等问题,本文以明胶为囊材,采用单凝聚法制备伊维菌素长效注射微胶囊油混悬剂。以微胶囊的粒径、载药量和包封率为制备工艺的优化指标,采用分光光度法测定微胶囊内药物含量及包封率。结果显示：最佳工艺制备的微胶囊的平均包封率为63.2%,载药量为18.3%,微胶囊的正圆度高、表面平滑,粒径分布在20~50 μm,药物呈缓慢持续释放,体外累计释放率18 h为30.0%,44 h后仅为51.0%。伊维菌素微胶囊制剂可大大增加体内留存时间,提高生物利用度,缓释效果显著。  相似文献   

11.
试验选用96头平均体重14.82 kg左右的杜×长×大断奶仔猪,随机分成4组,每组3栏,每栏8头(公母各半)。对照组饲喂基础日粮,试验1、2、3组分别添加1%80目白术、0.2%白术多糖和1%微米白术。试验期30 d。结果表明:在生长性能方面,与对照组相比,1%微米白术添加组可显著提高日增重(P0.05)、降低饲料增重比和腹泻率,而且效果优于1%80目白术组和0.2%白术多糖组,在肠道形态和肠道微生态区系方面,与对照组相比,日粮添加1%80目白术、0.2%白术多糖、1%微米白术均可不同程度的提高十二指肠和空肠的绒毛高度,加深十二指肠和空肠的隐窝深度,并且增加肠道微生态区系的多样性,其中以1%微米白术添加组的效果最佳。  相似文献   

12.
Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.  相似文献   

13.
1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.  相似文献   

14.
Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.  相似文献   

15.
Genetic variations in chromosome Y are enabling researchers to identify paternal lineages, which are informative for introgressions and migrations. In this study, the male‐specific region markers, sex‐determining region‐Y (SRY), amelogenin (AMELY) and zinc finger (ZFY) were analysed in seven Turkish native goat breeds, Angora, Kilis, Hair, Honaml?, Norduz, Gürcü and Abaza. A SNP in the ZFY gene defined a new haplotype Y2C. All domestic haplogroups originate from Capra aegagrus, while the finding of Y1A, Y1B, Y2A and Y2C in 32, 4, 126 and 2 Turkish domestic goats, respectively, appears to indicate a predomestic origin of the major haplotypes. The occurrence of four haplotypes in the Hair goat and, in contrast, a frequency of 96% of Y1A in the Kilis breed illustrate that Y‐chromosomal variants have a more breed‐dependent distribution than mitochondrial or autosomal DNA. This probably reflects male founder effects, but a role in adaptation cannot be excluded.  相似文献   

16.
Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.  相似文献   

17.
The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.  相似文献   

18.
The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.  相似文献   

19.
The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.  相似文献   

20.
Infectious diseases have always been a terrible scourge for humans. The appearance of these plagues, as they were called without distinction, was generally connected to various conditions: asters, climatic changes or religious reasons. The concept of contagious, and then infectious, diseases came slowly. Variolation, i.e. transmission of ‘virulent’ matter to induce a natural disease and the immunity against it, was brought from Constantinople to England by Lady Montague, in 1721. This ‘variolation’ technique was also often performed in veterinary medicine against diseases like sheep-pox or pleuropneumonia. As ‘vaccination’ is the term generally accepted for ‘immunisation’, variolation can be the word designating such a technique. The second period of the history of immunisation began, in 1880, with the studies of Pasteur and his collaborators. A great number of bacterial vaccines were developed: dead, live but attenuated or only parts of pathogens. The viruses were produced in animals, then in eggs and at last, in tissue cultures. Second generation vaccines appeared with genetic engineering: recombinant vaccines, vector vaccines, nucleic acids vaccines, and markers vaccines, among others. These novel technologies can permit the development of new ones and improve the quality of the vaccines already existing.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号