幽门螺杆菌动物模型研究进展

幽门螺杆菌动物模型用于HP相关疾病和HP疫苗作用的研究。常规实验动物包括悉生猪、悉生狗、非人类灵长动物、猫、雪貂、小鼠、大鼠、沙鼠等。猫螺杆菌和雪貂螺杆菌感染也被用于模型研究。最近,转基因小鼠和基因敲除小鼠也被用作幽门螺杆菌动物模型研究。     

关于Gnotobiology一词汉译的浅见

关于gnotobiotes一词,我见到过6种汉译:定菌动物、既知菌动物、已知菌丛动物、已知生物体择生生物、悉生生物。凡是汉译词中带有“菌”字的,我认为都不可取。因为gnotobiotes是可能不带菌,而是带有病毒、原虫、蠕虫、甚至昆虫等寄生物的。 魏曦教授在本刊8卷3期发表的“关于     

《医学动物实验技术》

正本书由国家科学技术学术著作出版基金资助、人民卫生出版社出版,为技术类工具书。内容分为十二篇:动物实验室设计及设备配置;动物实验室认证与规范运行;动物实验基本技术;动物胚胎工程;动物遗传工程;实验动物干细胞技术;无菌及悉生动物技术;动物表现分析技术;人类疾病动物模型;药品医疗器械评价及检定动物实验技术;实验动物比较基因组学;动物实验设计与统计分析、专利申报、论文写作。     

使用悉生大鼠建立肠道膜菌群的分析方法

为了深入地研究肠道菌群的生物屏障作用,我们使用悉生动物,建立了肠道膜菌群的研究方法,此法与传统方法相比不仅选择效果好,而且各类菌的活菌计数量高。使用悉生动物的研究结果表明:空肠膜菌群杆菌数为5.09±0.09.肠球菌数为4.49±0.23,乳杆菌数为5.82±0.07,类杆菌数为5.56±0.43,双歧杆菌数为5.19±0.24。回肠膜菌群数依次为6.07±0.29,6.57±0.11,7.40±0.13,6.56±0.09,7.68±0.08。盲肠的膜菌群数依次为6.11±0.45,6.40±0.17,7.04±0.31,7.57±0.22,7.51±0.11。     

悉生豚鼠体内复方双歧杆菌制剂对福氏志贺氏菌的作用

复方双歧杆菌制剂中,双歧杆菌(Bif.bifidum),乳酸杆菌(L.acidophilus),粪链球菌(Str.faecalis)三种菌都是人和动物肠道正常菌群之一,要研究它们和肠道致病菌之间的关系,在普通动物体内是无法观察到.在国内我们首次应用悉生豚鼠进行复方双歧杆菌制剂对福氏志贺氏菌作用的研究,发现在悉生豚鼠体内复方双歧杆菌制剂对感染后的豚鼠有较明显的保护作用,保护率为75%,实验组未获得保护的豚鼠死亡时间较对照组延长6～10天,而对照组豚鼠在感染后24～48小时全部死亡,解剖后在肠道分泌物中分离出福氏志贺氏菌.本实验证明:复方双歧杆菌制剂是治疗腹泻较好的生物制剂,尤其对因菌群失调而引起的腹泻更是理想的治疗方法。     

中国的蠺丝业

蚕丝是中国伟大的发明,传说还在四千五百多年前的“黄帝时代”,传说那黄帝元妃,名叫缧祖,她有一个花园,园里长了很多桑树,她常常去桑树下面乘风凉。有一天,她进得园来,听见树上(口悉)(口悉)嗦嗦地好像小雨下在叶子上的声音,却没有雨点落下来。缧祖抬头仔细一看,便发见了那吃桑叶的蚕,正在那儿做茧子。旁边的侍女说道:“蚕做好一个茧子,要花三日三夜,茧子做好了以后,蚕便变成了蛹,躲在茧子里,过了一个月,又变成蛾子,把茧子咬破飞出来。”缧祖     

幽门螺杆菌动物模型研究进展

幽门螺杆菌动物模型用于H.pylori相关疾病和H.pylori疫苗作用的研究。常规实验动物包括翻生猪、悉生狗、非人类灵长动物、猫、雪貂、小鼠、大鼠、沙鼠等。猫螺杆菌和雪貂螺杆菌感染也被用于模型研究。最近,转基因小鼠和基因敲除小鼠也被用作幽门螺杆菌动物模型研究。     

无菌动物及其在微生物与宿主互作机制研究中的应用

无菌动物是指通过现代技术手段在其体内外的任何部位均检测不出细菌、真菌、放线菌、支原体、衣原体、螺旋体、立克次氏体、病毒、原生动物和寄生虫的动物。无菌动物因其不携带任何微生物,可转化为携带特定微生物的动物,同时因其免疫系统处于休眠状态,对微生物感染异常敏感,可建立多种悉生动物模型,用于特定微生物感染实验和致病机制研究。此外,无菌动物作为关键工具,是研究菌群与疾病关系的核心,在微生物与宿主健康、疾病和感染机制研究过程中,起着不可替代的作用。本文将对无菌动物及其在微生物与宿主互作机制研究中的应用进行简要综述。     

幽门螺杆菌动物感染模型的研究近况

动物感染模型对于幽门螺杆菌致病机制的研究、疫苗的研制和药物的筛选具有十分重要的作用。已报道的用于建立该菌动物感染模型的动物有小鼠、大鼠、蒙古沙鼠、豚鼠、猫、狗、悉生生物猪和灵长类动物等。此外也有人利用猫胃螺杆菌感染的小鼠、大鼠模型和鼬鼠螺杆菌感染的雪貂模型来研究幽门螺杆菌。本文就各种幽门螺杆菌动物感染模型的优缺点、适应范围及存在问题作一简要介绍。     

前进中的悉生生物学

前进中的悉生生物学凌代文第十二届国际悉生生物学学术讨论会（ＴｈｅⅩⅡＩｎｔｅｒｎａｔｉｏｎａｌＳｙｍｐｏｓｉｕｍｏｎＧｎｏ－ｔｏｂｉｏｌｏｇｙ）于１９９６年６月２３日－２８日在美国夏威夷的檀香山召开。本届会议由日本东海医科大学Ｈａｓｈｉｍｏｔｏ,ｋ,...     

Protective effect of bifidus milk on the experimental infection with Salmonella enteritidis subsp. typhimurium in conventional and gnotobiotic mice

The ability of Bifidobacterium bifidum from a commercial bifidus milk to antagonize Salmonella enteritidis subsp. typhimurium in vivo, and to reduce the pathological consequences for the host, was determined using conventional and gnotobiotic mice. Conventional animals received daily, by gavage, 0.1 ml bifidus milk containing about 10(9) cfu B. bifidum and germ-free animals received a single 0.1 ml dose. The conventional and gnotobiotic groups were challenged orally with 10(2) cfu of the pathogenic bacteria 5 and/or 10 d after the beginning of treatment. Control groups were treated with milk. Bifidus milk protected both animal models against the challenge with the pathogenic bacteria, as demonstrated by survival and histopathological data. However, to obtain the protective effect in gnotobiotic animals, the treatment had to be initiated 10 d before the challenge. In experimental and control gnotobiotic mice, Salm. enteritidis subsp. typhimurium became similarly established at levels ranging from 10(8) to 10(9) viable cells g-1 of faeces and remained at these high levels until the animals died or were sacrificed. It was concluded that the protection against Salm. enteritidis subsp. typhimurium observed in conventional and gnotobiotic mice treated with bifidus milk was not due to the reduction of the intestinal populations of the pathogenic bacteria.     

Propagation of ribonucleic acid coliphages in gnotobiotic mice.

To clarify the propagation cycle of bacteriophages in their natural habitats, we tested whether animals could support ribonucleic acid (RNA) phage propagation in their intestines, using germfree mice as the test animal. Propagation of four different antigenic types of RNA phages was tested. No detectable propagation or colonization of RNA phages was observed either in germfree mice or in gnotobiotic mice infected with the F- strain of Escherichia coli. Propagation or colonization was observed when RNA phages were orally introduced into gnotobiotic mice harboring the F+ or F' strain of E. coli. These results were consistent with data for in vitro propagation experiments. Fecal titers of phages were monitored over 24 to 98 days and were found to vary from 10(5) to 10(11) plaque-forming units per g of feces. Streptomycin administration gradually led to the disappearance of bacteria and, concomitantly, the RNA phages. Phages recovered from gnotobiotic mice feces included some of novel antigenic types. The bacterial isolates recovered from gnotobiotic mice harboring F+ bacteria included the original F+ strain, strains which had become F-, and some which had become inefficient hosts for the propagation of RNA phages.     

Propagation of ribonucleic acid coliphages in gnotobiotic mice.

To clarify the propagation cycle of bacteriophages in their natural habitats, we tested whether animals could support ribonucleic acid (RNA) phage propagation in their intestines, using germfree mice as the test animal. Propagation of four different antigenic types of RNA phages was tested. No detectable propagation or colonization of RNA phages was observed either in germfree mice or in gnotobiotic mice infected with the F- strain of Escherichia coli. Propagation or colonization was observed when RNA phages were orally introduced into gnotobiotic mice harboring the F+ or F' strain of E. coli. These results were consistent with data for in vitro propagation experiments. Fecal titers of phages were monitored over 24 to 98 days and were found to vary from 10(5) to 10(11) plaque-forming units per g of feces. Streptomycin administration gradually led to the disappearance of bacteria and, concomitantly, the RNA phages. Phages recovered from gnotobiotic mice feces included some of novel antigenic types. The bacterial isolates recovered from gnotobiotic mice harboring F+ bacteria included the original F+ strain, strains which had become F-, and some which had become inefficient hosts for the propagation of RNA phages.     

Structure of the intestinal flora responsible for development of the gut immune system in a rodent model

The intestinal flora comprising indigenous, autochthonous bacteria is constantly present in the alimentary tract of host animals, including humans. The indigenous bacteria greatly affect the structure and functions of the intestinal mucosa. Studies involving gnotobiotic mice or rats have shown that the presence of limited kinds of intestinal bacteria is responsible for the development of the gut immune system, such as secretory IgA, major histocompatibility complex molecules and intraepithelial lymphocytes. Understanding of the structure of the intestinal flora or the organization of the microbial population in the intestine, based on evaluation of the immunological responses, may clarify its functions in the host animal.     

A new technique to determine hydrogen excreted by gnotobiotic rats

A new system, that allowed the monitoring of hydrogen (H2) excretion by gnotobiotic rats without affecting their defined microbial status, was developed. The system consists of an isolator containing a chamber for an experimental animal, and a life-support system (LSS), with a sampling port outside the isolator connected to it. H2 accumulation in the system was measured by analysing a defined volume of gas after removal. H2 concentrations were determined with an electrochemical cell or by gas chromatography. To validate this technique, H2 excretion by germ-free (GF) and mono-associated rats fed a chemically defined diet was measured after oral application of lactulose. Mono-associated rats had been obtained by colonizing GF rats with a H2-producing Clostridium perfringens type A strain isolated from human faeces of a healthy volunteer. Application of 50 mg lactulose to the mono-associated rats resulted in a significant increase in H2 excretion. The net H2 excretion was 7.82+/-1.28 ml H2 in 12 h corresponding to a net maximal rate of 1.1+/-0.3 ml H2/h. In contrast, in experiments with GF rats, less than 0.13 ml H2 were detectable within 12 h. The technique presented is a useful tool for studying bacterial H2 metabolism in vivo under gnotobiotic conditions.     

Animal models for gastric Helicobacter immunology and vaccine studies

Over the last decade animal models have been used extensively to investigate disease processes and therapy for Helicobacter pylori infections. The H. pylori animal models which have been used in pathogenesis and vaccine studies include the gnotobiotic pig, non-human primates, cats, dogs, and several species of rodents including mice, rats, gerbils and guinea pigs. H. felis infection of mice and H. mustelae infection of ferrets have also been used. Recently, investigators have begun using transgenic mice and gene-targeted 'knock-out' mice to investigate Helicobacter infections. Each of these animal models has distinct advantages and disadvantages which are discussed in this minireview. The choice of an animal model is dictated by factors such as cost and an understanding of how each model will or will not allow fulfillment of experimental objectives.     

Rearing of conventional and gnotobiotic nonhuman primates (Pan troglodytes, Papio cynocephalus, Saguinus nigricollis).

Rearing techniques for conventional and gnotobiotic nonhuman primates are described. Up to four months of age there was no significant difference in weight gain between conventionally and gnotobiotically reared chimpanzees or baboons. After four months, gnotobiotic chimpanzees exceeded their conventional counterparts in weight gain, whereas conventional baboons showed higher weight gain than gnotobiotic baboons. Gnotobiotic chimpanzees and baboons had significantly lower absolute numbers of neutrophils than their conventional counterparts, but the absolute numbers of lymphocytes were not different. The gnotobiotic rearing of marmosets is also reported.     

Effect of Saccharomyces boulardii against experimental oral infection with Salmonella typhimurium and Shigella flexneri in conventional and gnotobiotic mice

A.C.P. RODRIGUES, R.M. NARDI, E.A. BAMBIRRA, E.C. VIEIRA AND J.R. NICOLI. 1996. Saccharomyces boulardii was shown to be capable of inhibiting multiplication of enteropathogenic bacteria in vitro and is currently used for its anti-diarrhoea properties. We studied the capacity of this yeast to antagonize Salmonella typhimurium and Shigella flexneri in the intestinal tract of conventional or gnotobiotic NMRI mice. Conventional animals were given daily 10 mg doses of S. boulardii , whereas germ-free animals were given a single 10 mg dose. Both groups were challenged orally 5 d later with the pathogenic bacteria (10⁸ or 10² viable cells, respectively). Control groups were treated with saline instead of S. boulardii. Mortality and/or histopathological data showed a protective effect against the pathogenic bacteria in yeast-treated mice. Saccharomyces boulardii colonized the digestive tract of gnotobiotic mice and the number of viable cells ranged around 10¹⁰ g^-1 of faeces. In experimental and control gnotobiotic animals, Salm. typhimurium and Sh. flexneri became rapidly established at a level of about 10¹⁰ viable cells g^-1 of faeces and remained at high levels until the animals died or were sacrificed. The protection against Salm. typhimurium and Sh. flexneri obtained in conventional and/or gnotobiotic mice previously associated with S. boulardii is not due to the reduction of the bacterial populations in the intestines.     

Distribution and effects of a defined six-member murine-derived microflora in gnotobiotic gerbils.

The gnotobiotic gerbil was selected as a model with which to study the effects of colonization with a defined microflora on organ morphology, histology, and selected blood biochemical parameters. Gerbils were maintained germfree for 13 months but failed to reproduce, presumably because of the enlarged cecum. A colony of gnotobiotic gerbils that was associated with a bacterial flora consisting of Lactobacillus brevis, Streptococcus faecalis, Staphylococcus epidermidis, Bacteroides vulgatus, Enterobacter aerogenes, and a Fusobacterium sp. was established. These gnotobiotic gerbils had smaller ceca than germfree gerbils and proved capable of reproduction. Except for the presence of large numbers of Bacteroides organisms in the stomach and greater numbers of S. epidermidis in gnotobiotic gerbils, the number and location of gastrointestinal bacteria were similar in conventional and gnotobiotic gerbils. Bacteroides sp. was the second most predominant microorganism present in gnotobiotic gerbils, whereas clostridia were reported to be the second most predominant microorganism in conventional gerbils. Microscopic examination of direct-impression smears indicated that fusobacteria were present on mucosal surfaces. Intestines of gnotobiotic gerbils weighed twice as much as the intestines of conventional gerbils. Intestinal tissue water weight values from conventional and gnotobiotic gerbils were similar. Histological examination of gerbil intestinal tissue revealed no cellular hypertrophy and no evidence of inflammation in gnotobiotic gerbil intestines. Spleens of gnotobiotic gerbils showed no germinal center stimulation. Statistical differences in total serum glucose, serum protein, and hematocrit levels were found between conventional and gnotobiotic gerbils.     

Effects of bacterial colonization on the porcine intestinal proteome

The gastrointestinal tract harbors a complex community of bacteria, of which many may be beneficial. Studies of germ-free animal models have shown that the gastrointestinal microbiota not only assists in making nutrients available for the host but also contributes to intestinal health and development. We studied small intestinal protein expression patterns in gnotobiotic pigs maintained germ-free, or monoassociated with either Lactobacillus fermentum or non-pathogenic Escherichia coli. A common reference design in combination with labeling with stable isobaric tags allowed the individual comparison of 12 animals. Our results showed that bacterial colonization differentially affected mechanisms such as proteolysis, epithelial proliferation, and lipid metabolism, which is in good agreement with previous studies of other germ-free animal models. We have also found that E. coli has a profound effect on actin remodeling and intestinal proliferation, which may be related to stimulated migration and turnover of enterocytes. Regulations related to L. fermentum colonization involved individual markers for immunoregulatory mechanisms.