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At least 1,171 records · Page 65Linked to original sources
PubMed1998

Constitutive IL-10 production accounts for the high NK sensitivity, low MHC class I expression, and poor transporter associated with antigen processing (TAP)-1/2 function in the prototype NK target YAC-1.

Tumor cells that are treated with rIL-10 or transfected with the IL-10 gene show phenotypic changes. These include low but peptide-inducible expression of MHC class I, low sensitivity to specific CTL-mediated lysis, and increased NK sensitivity. In vitro-established mouse tumor lines were screened for IL-10 expression and production, and a large proportion of plasmocytomas or T cell lymphomas were found to produce IL-10. Since one of these lines was the prototype NK target cell YAC-1, we investigated whether the high IL-10 production of this cell line was related to its high NK sensitivity and its defects in MHC class I expression. The decrease in H-2 expression following the in vitro culture of in vivo-passaged YAC-1 cells was accompanied by a gradual increase in IL-10 production, whereas the reverse was found when passing in vitro-grown YAC-1 in vivo as an ascites tumor in syngenic mice. In addition, differences in YAC-1 MHC class I expression correlated with alterations in the functional activity of TAP-1/2 proteins. YAC-1 cells that were transduced with a retroviral IL-10 antisense construct (Y-IL-10 AS) only produced about half of the IL-10 that was produced by YAC-1 transduced with the control construct (Y-IL-10 Mock). Relative to Y-IL-10 Mock cells, the expression of H-2 on Y-IL-10 AS cells was markedly increased, and NK sensitivity was decreased. These data argue for a mechanism wherein IL-10 production is causally related to the low H-2 expression, decreased TAP function, and high NK sensitivity of YAC-1 cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

2001 Census output areas: from concept to prototype.

This article describes the development of a prototype output area production system for the 2001 Census. A number of outstanding design issues concerning 2001 output areas are explained, and the implications of using a geographical information system for the management of census geography are explored.

Censuses↗
PubMed2001

Augmented reality fundus biomicroscopy: a working clinical prototype.

BACKGROUND: To guide treatment for macular diseases and to facilitate real-time image correlation, measurement, and comparison, we developed a method for direct overlay of previously stored photographic and angiographic images onto the real-time slitlamp fundus view. METHODS: Previously acquired fundus photographs and angiography images were digitized. A slitlamp interfaced to a charge-coupled device camera, framegrabber, and computer allowed for real-time acquisition and digitization of slitlamp fundus images that was synchronous with posterior segment examination. Custom-developed video injectors containing a miniature cathode ray tube display allowed for real-time superposition of angiographic images to the fundus view. Registration and tracking algorithms were developed and deployed in C++. The feasibility of this approach was demonstrated in 5 human subjects. RESULTS: The computer-vision algorithms provided robust registration, tracking, and image overlay of previously stored photographic and angiographic images directly onto the real-time fundus view. Accurate tracking was demonstrated with updates at 3 to 5 Hz. Direct overlay of previously stored images confirmed registration accuracy, but examiners preferred a more simple rendering that included only relevant information and eliminated extraneous, potentially confusing image data. CONCLUSIONS: Slitlamp-based video injection of previously stored images allows for accurate, robust, real-time correlation and comparison to the biomicroscopic fundus view in human subjects.

Algorithms↗
PubMed1997

Susceptibility of transgenic mice carrying human prototype c-Ha-ras gene in a short-term carcinogenicity study of vinyl carbamate and ras gene analyses of the induced tumors.

To determine if hemizygous transgenic mice carrying the human c-Ha-ras gene (CB6F1-Tg Hras2 mice (Hras2 mice)) are susceptible to the carcinogenic potential of known murine carcinogens, male and female Hras2 mice and their non-transgenic CB6F1 littermates (non-Tg mice) were each given a single intraperitoneal injection of 60 mg of vinyl carbamate (VC)/kg body weight or saline (vehicle control) and monitored for 16 wk without further treatment. At necropsy, grossly visible tumors were fixed for histopathologic diagnosis and, when of sufficient size, portions were frozen for subsequent molecular analysis. Nine of 31 male and nine of 29 female Hras2 mice treated with VC died within 16 wk as a result of lung tumor burden. At the termination of the study, lung tumors (alveolar-bronchiolar epithelial neoplasms and hemangiosarcomas) and focal alveolar-bronchiolar hyperplasias were present in both sexes of Hras2 and non-Tg mice treated with VC; there were significantly more proliferative lung lesions in Hras2 than non-Tg mice. Splenic hemangiosarcomas and squamous cell tumors of the forestomach were induced in male and female VC-treated Hras2 mice but not in VC-treated non-Tg mice. Polymerase chain reaction-single-strand conformation polymorphism analysis and DNA sequencing of the induced lung tumors revealed point mutations at codon 61 of the transgene in two of 29 lung tumors (one of 16 in males and one of 13 in females) from VC-treated Hras2 mice; no mutations in murine Ki-ras were found in these tumors. Point mutations at codons 12 and 61 of the murine Ki-ras gene were observed, however, in one of 10 and six of 10 lung tumors respectively, from VC-treated non-Tg mice. These findings indicate that Hras2 mice are highly sensitive to pulmonary neoplasms and splenic and lung hemangiosarcomas after treatment with VC. The molecular analyses suggest that point mutations of the transgene and the murine Ki-ras gene do not play a major role in VC induction of pulmonary neoplasms in these transgenic mice.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed2000

A density-functional theory based study on the 16O/18O-exchange reactions of the prototype iron-oxygen compounds FeO+ and FeOH+ with H2(18)O in the gas phase

The mechanism of the degenerate 16O/18O exchange in the reactions of FeO+ and FeOH+ with water is examined by density functional theory. Based on previous experimental work (Chem. Eur. J. 1999, 5, 1176), two possible reaction pathways are investigated for both systems. The first mechanism consists of one (for FeOH+ + H20) or two (for FeO+ + H20) 1,3-hydrogen migrations from one oxygen atom to the other; the iron atom is not directly involved in these OH bond activations. The second route comprises a series of two (for FeOH+ + H20) or four (for FeO+ + H20) 1,2-hydrogen migration steps which involve the intermediate formations of metal-hydrogen bonds. Both mechanisms are evaluated under consideration of the respective low- and high spin potential-energy surfaces. The computational results show a clear preference for the 1,3-routes occurring on the respective high-spin surfaces bypassing the intermediacy of high-valent iron compounds having FeH bonds.

Journal Article↗
PubMed2001

A [2]catenane and a [2]rotaxane as prototypes of topological and Euclidean molecular "rubber gloves".

A [2]catenane and a [2]rotaxane have been prepared from a C2-symmetric, 2,9-diphenyl-1,10-phenanthroline-based (dpp-based) macrocycle incorporating a 1,5-dioxynaphthalene subunit by means of the transition metal templated technique. In the case of the catenane, this macrocycle is interlocked with a dpp-based macrocycle that is oriented through the location of a p-tolyl substituent in the 4-position of the phenanthroline subunit. In the case of the rotaxane, the C2-symmetric macrocycle is threaded onto an oriented, dumbbell-shaped molecule, based on the same 4-p-tolyl-1,10-phenanthroline subunit, which bears tetraarylmethane stoppers. Both species are chemically achiral molecules, yet they are composed entirely of asymmetric, mirror-image conformations. Conformational enantiomerization processes therefore take place exclusively by chiral pathways, conferring on these molecules the "rubber glove" property. However, while the molecular graph (constitutional formula) of the [2]rotaxane can be deformed into a planar and, hence, rigidly achiral representation, a feature shared by a few other compounds in the literature that have been characterized as "Euclidean rubber gloves", the molecular graph of the [2]catenane cannot be deformed in this way. It therefore has the unique property of being a chemically achiral "topological rubber glove".

Journal Article↗
PubMed1999

Proton ATPases in bacteria: comparison to Escherichia coli F1F0 as the prototype.

The F1F0 ATP synthase complex of Escherichia coli functions reversibly in coupling proton translocation to ATP synthesis or hydrolysis. The structural organization and subunit composition corresponds to that seen in many other bacteria, i.e. a membrane extrinsic F1 sector with five subunits in an alpha 3 beta 3 gamma delta epsilon stoichiometry, and a membrane-traversing F0 sector with three subunits in an a1b2c12 stoichiometry. The structure of much of the F1 sector is known from a X-ray diffraction model. During function, The gamma subunit is known to rotate within a hexameric ring of alternating alpha and beta subunits to promote sequential substrate binding and product release from catalytic sites on the three beta subunits. Proton transport through F0 must be coupled to this rotation. Subunit c folds in the membrane as a hairpin to two alpha helices to generate the proton-binding site in F0. Its structure was determined by NMR, and the structure of the c oligomer was deduced by cross-linking experiments and molecular mechanics calculations. The implications of the oligomeric structure of subunit c will be considered and related to the H+/ATP pumping ratio, P/O ratios and the cation-binding site in other types of F0. The possible limits of the structure in changing the ion-binding specificity, stoichiometry and routes of proton entrance/exit to the binding site will be considered.

Animals↗
PubMed2004

Retinoblastoma: revisiting the model prototype of inherited cancer.

Hereditary retinoblastoma is an autosomal dominant disorder caused by mutations in the RB1 gene. Analysis of this rare condition has helped to elucidate the mechanisms underlying hereditary cancer predisposition in general. As identification of RB1 gene mutations has become a part of clinical management of patients with retinoblastoma, there is now a wealth of data. In this article, we summarize the current knowledge on the relations between the genotype and phenotypic expression. Moreover, detailed analysis of genotype-phenotype relations shows that hereditary retinoblastoma has features of a complex trait.

Child, Preschool↗