PubMed · 4930673
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R Powles, L Balchin, G A Currie, P Alexander. 1971-05-21. Specific autostimulating factor released by lymphocytes.. https://doi.org/10.1038/231161a0
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Mycoplasma arthritidis-derived mitogen (MAM), a bacterial superantigen, has been crystallized in complex with its human receptor, major histocompatibility complex (MHC) class II antigen, by the hanging-drop vapor-diffusion method. Crystals were obtained under three conditions, with ammonium sulfate, phosphate salt and PEG 8000 as the precipitant. The crystals grown under these conditions all belong to space group I222, with the same unit-cell parameters: a = 137.4, b = 178.2, c = 179.6 A. Diffraction data were collected to 3.3 and 3.4 A resolution from crystals of native and selenomethionylated MAM-MHC complexes, respectively. Self- and cross-rotation function calculations suggest the presence of two complex molecules in the asymmetric unit, resulting in a V(M) of 4.0 and a solvent content of 69%. An interpretable electron-density map was produced using a combination of molecular replacement and SAD phasing.
OBJECTIVE: To investigate the distribution of H.pylori antigens in the gastric mucosa in patients with H.pylori infection, and the relationship between the distribution and gastric cancer. METHODS: Of 112 patients confirmed by pathological study to have chronic superficial gastritis, precancerous changes (chronic atrophic gastritis, intestinal metaplasia or atypical hyperplasia) and gastric cancer, 28 were H.pylori negative and 84 were H.pylori positive. H.pylori antigens in the gastric mucosa were detected by immunohistochemistry. RESULTS: The H.pylori positive group, comprised 12 of 22 (50.0%) in the chronic superficial gastritis group, 22 of 25 (88.0%) in the precancerous changes group and 13 of 35 (37.1%) in the gastric cancer group. The positive rates of H.pylori antigens in the cytoplasm progressively increased, respectively at 0.0% (0/12), 63.6% (14/22) and 84.6% (11/13) for the same groups (chi(2)=19.76, P=0.000); H.pylori antigens were located in the mucus layer and above the neck of the mucosal gland in 9 of 12 (75.0%) cases with chronic superficial gastritis, at the neck of the mucosal gland and the isthmus in 12 of 22 (54.5%) cases with precancerous changes, below the isthmus in 9 of 13 (69.2%) cases with gastric cancer (chi(2)=25.30, P=0.000). In the H.pylori negative group, no H.pylori antigen was observed. CONCLUSION: With the progression of chronic superficial gastritis-->precancerous changes-->gastric cancer, H.pylori antigens progressively migrated from the outer part to the inner part of the cell, and from the superficial to the deep gastric mucosa.
Selection of genetically modified cells is a critical step to engineer the cells with desired properties. While antibiotic selection has been commonly used, administration of cytotoxic drugs often leads to deleterious effects not only to inert cells but also to transfected or transduced ones. To overcome this problem, a positive screening method for genetically modified cells is proposed using a pair of chimeric receptors that trigger a growth signal in response to a specific antigen. Either V(H) or V(L) region of anti-hen egg lysozyme (HEL) antibody HyHEL-10 was fused to extracellular D2 domain of erythropoietin receptor (EpoR) and transmembrane/cytoplasmic domains of either EpoR or gp130. A model transgene, enhanced green fluorescent protein (EGFP) and the chimeric receptor genes that reconstituted functional Fv were retrovirally co-infected to interleukin (IL)-3-dependent Ba/F3 cells, followed by direct HEL selection in the absence of IL-3. Consequently, a single round of selection led to a single population of EGFP-positive cells. The detailed protocol of the method termed antigen-mediated genetically modified cell amplification (AMEGA) is described.