Mechanisms of natural resistance to mouse typhoid

The early, innate resistance phase in mouse typhoid is largely controlled by a single gene (unlike the later, polygenic immune phase), designated Ity, which may be identical to those controlling resistance to Leishmania (Lsh) and mycobacteria (Bcg). The gene product and its function are unknown. Athymic (nu/nu) mice showed greater early resistance to salmonella infection than euthymic littermates, but only if they were already naturally resistant CBA (Ityr). Athymic susceptible Balb/c (Itys) were not different from the controls. The Ity mechanism is highly radio-resistant: 800 R whole body irradiation does not modify the early Ity phenotype in Balb/c and A/J mice, as measured by early in vivo net bacterial growth; this, however, increases sharply on day 3-4, when growth curves plateau in controls (immune response). Bone marrow radiation chimeras infected 3 months after the transfer confirm that, while the donor genotype determines the Ity recipient phenotype in single chimeras, double chimeras (Itys + Ityr) leads to Ityr are susceptible or intermediate in both semiallogeneic and syngeneic models. The typhoid relapse following cessation of antibiotic therapy was greater in susceptible than in resistant mice. In lethally infected mice, ampicillin decreased the bacterial load twice as fast in susceptible Balb/c than in resistant (B10 X A/J)F1 mice, but they required much more prolonged treatment to develop effective immunity. Considered collectively, the present data is consistent with the view that early resistance is thymus independent and relies on innate mechanisms present in radioresistant bone marrow derived cells that in some way provide an environment which favours a more rapid in vivo division rate of the organism in susceptible mice.     

Induction of proinflammatory responses in the human monocytic cell line THP-1 by Campylobacter jejuni

Campylobacter jejuni can cause an enteritis that is associated with an acute inflammatory response at the gut epithelial surface. The signals inducing inflammation are unknown. C. jejuni can penetrate the intestinal epithelial barrier and may then interact with leucocytes, potentially inducing proinflammatory responses. To investigate this, we studied the interaction of C. jejuni with the human monocytic cell line THP-1 and show that a range of proinflammatory cytokines and chemokines is induced. These include interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6, IL-8, and tumor necrosis factor alpha. Responses can be induced by killed Campylobacter as well as live bacteria and do not depend on the cytolethal distending toxin. C. jejuni infection of THP-1 cells triggers both nuclear translocation of functional NF-kappa B and stimulation of IL-1 alpha, indicating that NF-kappa B-dependent and -independent stimulation is occurring. The extent of proinflammatory cytokine stimulation suggests that monocytes might significantly contribute to intestinal inflammation and disease pathology.     

The embryo versus endometrium controversy revisited as it relates to predicting pregnancy outcome in in-vitro fertilization-embryo transfer cycles

To evaluate embryonic and endometrial factors for their value in predicting pregnancy outcome in in-vitro fertilization (IVF) and embryo transfer, a retrospective data collection and prospective uterine artery colour Doppler imaging study was performed in a university-based IVF-embryo transfer programme setting. A total of 210 patients were included and grouped as follows: (I) IVF with controlled ovarian stimulation (214 cycles); (II) frozen-thaw cycle of autologous embryos (30 cycles); (III) oocyte donation, no cryopreservation (12 cycles); (IV) frozen-thaw cycle with embryos from donated oocytes (10 cycles). Embryo quality was significantly better in pregnant than non-pregnant cycles (group I, P = 0.0104; groups II-IV, P = 0.0418). The endometrial echo was significantly thicker in pregnant versus non-pregnant patients in group I (P = 0.0059), but not in groups II-IV (P = 0.741). Past uterine surgery or abnormalities had no effect on pregnancy outcome. There were no significant differences in mean uterine artery resistance index or peak systolic velocity in pregnant versus non-pregnant patients in groups II-IV. Thus, embryo quality is the most reliable predictor of pregnancy outcome. Endometrial measurements were significantly thicker in subsequently pregnant patients only in group I, where the endometrium reflects the hormonal environment. Doppler parameters were not useful in predicting pregnancy outcome.      

Identification and characterisation of hyaluronate lyase from Streptococcus suis

Hyaluronate lyase, which catalyses the degradation of hyaluronic acid (HA), has been described from several pathogenic streptococcal species. We describe, for the first time, identification and purification of hyaluronate lyase from the zoonotic pig pathogen Streptococcus suis. We have cloned the hyaluronate lyase gene from S. suis and used it to generate an allelic replacement knock-out mutant of S. suis serotype 7 that can no longer biosynthesise the enzyme. Interestingly, a limited strain survey indicates that hyaluronate lyase activity is not present in all disease isolates of S. suis. Polyclonal anti-hyaluronate lyase anti-serum raised against our recombinant hyaluronate lyase has been used in Western blots, showing that hyaluronate lyase activity is always associated with the presence of protein of the expected size, whereas lack of hyaluronate lyase activity is due to truncation or absence of the enzyme. We show that hyaluronate lyase activity is required for S. suis to use HA polymer as a carbon source and that supplying exogenous recombinant hyaluronate lyase to all S. suis strains tested allowed fermentation of the resultant HA breakdown products.     

Role of Bordetella O antigen in respiratory tract infection

Lipopolysaccharide (LPS), as the major surface molecule of gram-negative bacteria, interacts with the host in complex ways, both inducing and protecting against aspects of inflammatory and adaptive immunity. The membrane-distal repeated carbohydrate structure of LPS, the O antigen, can prevent antibody functions and may vary as a mechanism of immune evasion. Genes of the wbm locus are required for the assembly of O antigen on the animal pathogen Bordetella bronchiseptica and the human pathogen B. parapertussis. However, the important human pathogen B. pertussis lacks these genes and a number of in vitro and in vivo characteristics associated with O antigen in other organisms. To determine the specific functions of O antigen in these closely related Bordetella subspecies, we compared wbm deletion (Deltawbm) mutants of B. bronchiseptica and B. parapertussis in a variety of assays relevant to natural respiratory tract infection. Complement was not activated or depleted by wild-type bordetellae expressing O antigen, but both Deltawbm mutants activated complement and were highly sensitive to complement-mediated killing in vitro. Although the O-antigen structures appear to be substantially similar, the two mutants differed strikingly in their defects within the respiratory tract. The B. parapertussis Deltawbm mutant was severely defective in colonization of the tracheas and lungs of mice, while the B. bronchiseptica Deltawbm mutant showed almost no defect. While in vitro characteristics such as serum resistance may be attributable to O antigen directly, the role of O antigen during infection appears to be more complex, possibly involving factors differing among the closely related bordetellae or different interactions between each one and its host.     

Digestibility and Compatibility of Mixed Diets and Faecal Consistency in Different Breeds of Dog

The digestive capacity of dogs varying in body size was tested. Digestive experiments were conducted with 10 different canine breeds (n = 66) with body weights ranging from 4.2 to 52.5 kg with 4–9 individuals. The animals were fed a canned or a dry commercial diet with a constant dry matter intake of 13 g/kg BW/day, except in Irish wolfhounds, which ingested only 10 g dry matter with the canned diet. Faecal dry matter was around 14% (absolutely) higher for the dry diet compared to the canned food, with a tendency in the larger breeds towards higher faecal water contents, less favourable faecal quality and increased numbers of defaecations. The Irish wolfhounds, the largest breed tested, had faeces with considerably lower water contents compared to Labrador retrievers, indicating that body weight is not the only factor to be considered. There were only small differences in the apparent digestibility of crude nutrients amongst the breeds. Sodium and potassium absorption was higher when the dry diet was fed compared to the canned food. In conclusion, breed and individual factors have to be taken into account when performing tests with dog food. Test panels for evaluating commercial diets should include breeds of larger body size and higher sensitivity to dietary disorders.     

口腔诊所信息管理系统的研究与开发

目的　研究利用计算机信息处理、数据库和图形技术 ,开发用于口腔诊所 (科室 )的信息管理系统。方法　在专家论证诊所 (科室 )的医疗现状和管理需求的基础上 ,制定我国口腔临床医疗操作代码 ,用PowerBuilder6 .0和SQLAnywhere数据库管理系统为开发工具 ;采用C语言作为图形开发工具 ,进行信息管理系统的研制。结果　该系统含 7个子系统 :患者信息管理、工作人员管理、财务管理、诊所资产管理、消耗品管理、技工委托、系统维护。经 8个单位试用 ,一年中累计管理患者约 110 0例。测试结果表明 ,系统具有较强和较完善的临床使用功能及方便的用户界面。结论　该系统能提高使用单位的临床医疗管理水平和效益。对提高医生的病历水平和积累研究资料也具有重要意义。