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PubMed1976

Protection against group B meningococcal disease. I. Comparison of group-specific and type-specific protection in the chick embryo model.

Protection against group B meningococcal infection was examined using the chick embryo. 12-day-old embryos were challenged intravenously with various meningococcal strains. The chick embryo has an active reticuloendothelial system but lacks functional complement. In this model we found that protection against group B infection was primarily group specific. The group B polysaccharide antibody is an effective opsonin, but is a very poor bactericidal antibody. In contrast, the serotype antibody was bactericidal but only slightly protective in the chick embryo where protection is primarily phagocytic in nature. The group-specific and type-specific antibodies are strongly synergistic. Minute amounts of group B polysaccharide antibody caused a very significant increase in the protective effects of the serotype antibody.

Animals↗
PubMed1978

Chicken embryo model for type III group B beta-hemolytic streptococcal septicemia.

A lethal septicemia was induced in 11- and 12-day-old chicken embryos with intravenous inoculation of relatively small numbers of a clinical isolate (GBBHS-III-Bell) or a reference strain (GBBHS-III-D136-C) of group B beta-hemolytic streptococci (GBBHS). GBBHS-III-Bell was more virulent than GBBHS-III-D136-C, and 11-day-old chicken embryos were more susceptible than 12-day-old chicken embryos. Type-specific rabbit antisera protected the embryos from bacterial challenge, and this protective effect was absorbed with homologous but not heterologous GBBHS strains. A heterologous antiserum and normal rabbit sera provided some protection, which could be absorbed with either homologous or heterologous GBBHS strains. The chicken embryo is a suitable animal model for the study of infection and immunity with GBBHS type III.

Animals↗
PubMedDate not supplied

Immunologic effects of low levels of ochratoxin A in ovo: utilization of a chicken embryo model.

Ochratoxin A (OA) was administered to 13-day-old chicken embryos via the chorioallantoic membrane. The 7-day LD50 value (day 20 incubation) of OA was calculated at 7.9 micrograms of OA. Ochratoxin-treated embryos (2.5 micrograms) had slight but significant changes in numbers of immunoglobulin-bearing cells in the bursa but not in the spleen. Chicks hatched from in ovo-treated eggs were challenged with 9 X 10(4) colony-forming units (CFU) of beta-hemolytic Escherichia coli (O1:K1) at 7 days of age via the thoracic air sac. Lesion scores of OA-treated chicks were equal to or less severe than those of controls. Hatchmates of the above chicks were vaccinated with a homologous killed E. coli bacterin (O1:K1) at both 2 and 4 weeks of age and challenged with 10(4) CFU of E. coli at 7 weeks. Post-challenge lesions were present in three vaccinated untreated controls and no OA-treated chicks. We conclude that although in ovo exposure to OA may marginally suppress immunoglobulin-bearing cells of bursa, chicks hatched from OA-treated eggs respond as well as controls to an antigen and resist infection by a virulent organism.

Animals↗
PubMed1992

The nutrition of the fetus with intestinal atresia: studies in the chick embryo model.

This article examines the effects of experimental prenatal intestinal obstruction on the growth and blood composition of chick embryos. Intestinal atresia (IA) was produced by bipolar bowel electrocoagulation in fertile eggs on the 14th day of incubation. The chicks killed on the 19th day were measured, weighed, and blood-sampled. Twenty-three control, 10 sham-operated, and 11 IA chicks were studied. Animals with IA were severely undernourished by weight (43.4 +/- 4.7 v 70.3 +/- 7.6% of egg weight, P < .001) and length (15.3 +/- 1.1 v 18.1 +/- 0.9 mm tibial length, P < .001) in comparison with sham-operated ones. Their hematocrit was slightly lower, and total protein increased. Prealbumin was absent in their sera and albumin, alpha and beta globulins were significantly decreased, whereas gamma-globulin was greatly increased. Sodium, potassium chloride, urea, and glucose remained within normal limits. The lack of placenta in the avian embryo precludes any supply of nutrients by this route and the ingestion of amniotic fluid, which is protein-rich after the 13th day of incubation, when the opening of the seroamniotic connection allows albumen to be mixed with it, becomes the main source of nutrients until hatching. Obstruction of the main incoming avenue by IA induces severe malnutrition in this model which relies on this route to a greater extent than the human fetus. In spite of the obvious biological differences between the avian embryo and the human fetus, the present evidence supports the hypothesis that prenatal interruption of the amniotic fluid transit contributes to fetal undergrowth in IA.

Amniotic Fluid↗
PubMed1986

Early spontaneous metastasis in the human epidermoid carcinoma HEp3/chick embryo model: contribution of incidental colonization.

In the experimental model system where human tumor cells (HEp3) are implanted on the chorioallantoic membrane (CAM) of the chick embryo, metastasis of HEp3 cells to the embryonic lung occurs within a few days. Such rapidity in tumor dissemination makes this an attractive and potentially useful model for studying the metastatic process. The model, however, involves microvascular trauma at the site of implantation and thus tumor cells may accidentally enter the circulation during implantation or shortly thereafter. If these cells are the cause of the lung metastasis subsequently measured, the model would be in effect a colonization system and not a true, spontaneous metastasis system. The possible contribution of accidental lung colonization to secondary tumor growth was therefore critically examined in this model. In standard metastasis assays, HEp3 was inoculated onto the CAMs of 10-day embryos, which were then incubated for various periods of time. The embryos' lungs were passaged to a second group of CAMs, incubated for 7 days to allow expansion of any HEp3 cells present, and then assayed for HEp3 cells by both microscopy and measurement of human plasminogen activator (PA) activity. Metastasis was evidenced by PA values above background (30 mU/mg protein). Morphological analysis of HEp3 cells in the embryonic lung correlated closely with PA values. To focus on the early stages of tumor dissemination when colonization might occur, the primary tumor was surgically excised from 38 embryos at various intervals after tumor inoculation, and after the operation embryos were allowed to develop to day 17. This procedure increased estimated assay sensitivity down to the level of 1 to 10 cells per lung in embryos operated on within 2 days of inoculation. Median PA values in the transplanted lungs were 13, 3, 37, 1,290 and 3,765 mU/mg protein in the groups operated on at 4 hr, 1, 2, 3 and 4 days after inoculation, respectively. Thus very few or no HEp3 cells arrest and grow in the lungs during the first 24 to 48 hr, but extensive metastasis occurs by 72-96 hr. Accidental colonization therefore plays no major part in the rapid pulmonary spread of HEp3 in this model.

Animals↗
PubMed1999

"Giving body" to embryos. Modeling, mechanism, and the microtome in late nineteenth-century anatomy.

Reinvestigating the work of the anatomist Wilhelm His (1831-1904) shows how engaging with models in three dimensions can revise our accounts of scientific change. His is known to historians of biology for articulating a mechanical approach to embryology and for inventing a section cutter, or microtome. Focusing on the wax models that he also made in the late 1860s shows how the other two innovations were linked; reconstructing embryos from the sections, His claimed, provided compelling evidence for mechanical views. The next generation of embryologists appropriated His's work selectively. In the 1880s anatomists took up "plastic reconstruction" to visualize the complex forms of higher vertebrate, especially human, embryos. An increasingly dominant experimental embryology, by contrast, drew on His's mechanical approach but had little use for the waxes and effaced them from the history of his work. Recovering these models offers a fresh perspective on the transformation of a central science of animal life and enriches our understanding of the relations between representation in two dimensions and three.

Animals↗
PubMed1998

A chick embryo model for metastatic human prostate cancer.

OBJECTIVE: To establish a suitable experimental model of bone and liver micrometastases from human prostate cancer for evaluating antitumor agents. METHODS: PC-3 cells, an androgen-independent prostate cancer cell line, were inoculated into the chorioallantoic membrane vein of 10-day-old chick embryos (10(6) cells/egg). The polymerase chain reaction product for the human beta-globin gene in chick embryo femur and liver was quantified at various time points after inoculation, when immunohistochemical staining was done for Ki-67 antigen and cytokeratin. The antitumor effect of suramin was evaluated using the model, as was regional blood flow after thallium injection. RESULTS: Micrometastases were identified in bone and liver 1 day after inoculation and grew to form established metastatic foci in all embryos. Suramin showed significant antitumor effect for liver metastases, but not for those in bone where blood flow was relatively low. CONCLUSION: The chick embryo system provides a highly reproducible model for bone and liver micrometastases from human prostate cancer, suitable for evaluating antineoplastic agents at an early stage of the metastatic process.

Animals↗
PubMed1993

A chicken embryo model to study the growth of human uveal melanoma.

In vitro cultured human uveal and skin melanoma cells were injected into the chicken embryonal eye at a stage when the immune system was not yet mature. The melanoma cells were accepted as part of the organism by the host. Even single melanoma cells could be traced by morphological methods as well as by immunohistochemical markers, such as S100, HMB-45, NKI/C3 and HNK-1. We found tumors in 20 and 40 percent of the embryos injected with uveal melanoma and skin melanoma, respectively. The embryos did not exhibit abnormal development of the eye as a result of the microinjection and had a high survival rate (90 and 60%, respectively) during embryogenesis. With this model for uveal melanoma the growth and possibly the metastatic behavior of human uveal melanoma cells can be studied.

Animals↗
PubMed1991

Inducibility of neoplastic transformation by Fujinami sarcoma virus in an in vitro chick embryo model for osteosarcoma: (i) effect of differentiation and (ii) investigation for in vivo growth potential in athymic mice.

We have described previously a novel in vitro model for the study of osteosarcoma. In this system, chick periosteal explants (CEP) transformed by the P140gag-fps oncoprotein of Fujinami avian sarcoma virus (FSV) exhibit biochemical and histological manifestations characteristic of osteosarcoma. In the present study, a hypothesis suggesting that more differentiated bone cells may resist FSV-induced oncogene changes was tested. In one set of experiments, CEP cultures were pretreated with a high dose of dexamethasone (10(-7) M), a bone cell differentiating agent, prior to FSV infection. In another experiment, CEP explants were allowed to grow and thus differentiate for various lengths of time in culture prior to infection with FSV. Another goal of this study was to show that FSV-transformed cultures were tumorigenic in nude mice. In experiments focusing on differentiation and FSV-transformation, it was found that groups that had been infected at stages where osteogenic differentiation had been induced or allowed to occur, exhibited significantly decreased values for biochemical parameters associated with osteosarcomatous transformation. Specifically, these parameters were alkaline and acid phosphatase activity, protein content, [3H]thymidine incorporation, mineral profile, and acidification of culture media. Furthermore, osteosarcomatous histopathological features were more prominent in cultures subjected to FSV infection prior to differentiation. These findings indicate that differentiated osteogenic cells are less susceptible to oncogene-mediated transformation than their progenitors. The tumorigenic potential of some CEP cultures transformed in vitro with FSV was examined by transplantation into athymic mice. FSV-transformed CEP cultures xenografted subcutaneously exhibited tumor formation, whereas xenografts of uninfected cultures did not grow or were completely resorbed. This demonstrates that FSV-transformed cultures are tumorigenic, and confirms that this model system is useful for the investigation of the mechanisms governing the development of osteosarcoma in vitro.

Animals↗
PubMed2005

Accessing key steps of human tumor progression in vivo by using an avian embryo model.

Experimental in vivo tumor models are essential for comprehending the dynamic process of human cancer progression, identifying therapeutic targets, and evaluating antitumor drugs. However, current rodent models are limited by high costs, long experimental duration, variability, restricted accessibility to the tumor, and major ethical concerns. To avoid these shortcomings, we investigated whether tumor growth on the chick chorio-allantoic membrane after human glioblastoma cell grafting would replicate characteristics of the human disease. Avascular tumors consistently formed within 2 days, then progressed through vascular endothelial growth factor receptor 2-dependent angiogenesis, associated with hemorrhage, necrosis, and peritumoral edema. Blocking of vascular endothelial growth factor receptor 2 and platelet-derived growth factor receptor signaling pathways by using small-molecule receptor tyrosine kinase inhibitors abrogated tumor development. Gene regulation during the angiogenic switch was analyzed by oligonucleotide microarrays. Defined sample selection for gene profiling permitted identification of regulated genes whose functions are associated mainly with tumor vascularization and growth. Furthermore, expression of known tumor progression genes identified in the screen (IL-6 and cysteine-rich angiogenic inducer 61) as well as potential regulators (lumican and F-box-only 6) follow similar patterns in patient glioma. The model reliably simulates key features of human glioma growth in a few days and thus could considerably increase the speed and efficacy of research on human tumor progression and preclinical drug screening.

Animals↗
PubMed1983

Immunogenic and protective properties of meningococcal serotype 2a protein in the hen-embryo model.

The ability of serotype 2 outer membrane protein (SP-2) of Neisseria meningitidis strain M986 serogroup B, serotype 2a (B, 2a) to stimulate antibody formation in hens and to confer protection against meningococcal challenge to embryos from immunised hens was investigated. Hens, housed with roosters, were immunised with 100 micrograms of SP-2 once a week for 5 weeks to maintain consistent levels of serum antibody during the study. Antibodies in sera of hens, yolks and plasma of 13-day-old embryos reacted in enzyme-linked immunosorbent assays and immunodiffusion with outer membrane vesicles (OMV) from serotypes 2a, 2b and 2c and most of the other prototype group B strains of N. meningitidis. Cross-reactivity of hen sera with most OMV appeared after only one injection of SP-2. Embryos from immunised hens were protected against challenge with up to 10,000 LD50 doses of either the homologous strain M986 (B, 2a) or strain M1011 (B, 2a). Protection was also evident against strains 614 (W135, 2a), S5896 (Y, 2c) and 2241 (C, 2a), but not against strain 78704 (C, 2a) despite strong cross-reactivity of antibody with OMV of this strain. Embryos were only partially protected against strain 78069 (B, 2b) and were fully susceptible to strain 2996 (B, 2b). Some protection was also obtained against meningococcal strains M1080 (B, 1), M982 (B,9), S3032 (B, 12), 79001 (B, 12), 79694 (B, 15-related) but not strain 77252 (B, nontypable). These results suggest that proteins extracted from both serotype 2a and 2b meningococci would provide the broadest protection against infection with group B, serotype 2 meningococci and that antibody, presumably directed against common peptides in the major outer membrane proteins, can prevent infection by some other disease-associated serotypes of N. meningitidis.

Animals↗
PubMed1986

Role of endotoxin in the pathogenicity of Neisseria gonorrhoeae colonial types 1, 4 and 5 determined by chicken embryo model.

The pathogenicity of Neisseria gonorrhoeae is a subject of considerable interest. It is believed that N. gonorrhoeae of colonial type 1 are pathogenic while those of type 4 are not. This is based on experimentation in human volunteers. The object of this study was to determine the reasons for the differences of susceptibility of chicken embryos to N. gonorrhoeae strains of colonial types 1, 4, 5 and 1R (a type-1 revertant from a non-pathogenic type 4 strain originally tested in human volunteers). Colonial types 1, 5, 1R and 4 caused mortality rates of 80, 70, 85 and 20% respectively. This variation in lethality appeared to depend upon the availability of free extra-cellular endotoxin and this was confirmed by chicken-embryo inoculation results and electronmicroscopy of normal and heated colonial types 1, 4 and 5. Similar results were obtained by inoculating purified endotoxins from these types into chicken embryos. The results of this study suggest that endotoxins play a major role in the pathogenicity of N. gonorrhoeae and that the variations in virulence of the colonial types depends on the stability of their cell walls.

Animals↗