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Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Processing of proteins into immunogenic forms and their subsequent presentation to T cells are mediated by APC. Monocytes and macrophages have long been recognized as one of the APC types. However, little is known about whether functional heterogeneity in processing and presentation exist within the monocyte/macrophage population. Past difficulties in obtaining clonal representatives of these populations have limited investigations in this regard. The c-myc-containing retrovirus MRV, previously shown to immortalize murine macrophages, was used to generate a large panel of macrophage cell clones. Differences observed in cell surface antigen expression and morphology demonstrated phenotypic heterogeneity among these clones. Functional heterogeneity was also observed both before and after IFN-gamma and IL-4 stimulation. The clones differ in their capacity to present several nominal antigens to T cell hybridomas. When parallel variation in ability to present both a nominal antigen and a peptide representing the epitope for which a T cell hybridoma was specific was observed among the clones, this variation correlated with the levels of surface MHC class II antigen the clones expressed. In contrast, diversity in the ability to process and present certain nominal antigens among clones that all presented the corresponding antigenic peptide with similar efficiency did not appear to be due to differences in levels of surface MHC class II molecules. Our results suggest that the macrophage clones are heterogeneous in their ability to both process and present several antigens. The ability to obtain macrophage tissue culture cell lines displaying phenotypic and functional heterogeneity should allow insight into the impact of normal macrophage heterogeneity on the outcome of immune responses in vivo.
J Immunol 1993 Sep 15
PMID:Monoclonal c-myc transformed macrophage cell lines. I. Heterogeneity in ability to process and present antigen. 810 18

The occurring frequency of 14 most common chemotherapy and anti-nausea drug side-effects was examined. The studies were performed on 29 women with ovarian cancer treated by total number of 125 chemotherapy courses (schedule PAC and Acy) and additionally, in order to eliminate nausea caused by the chemotherapy, by anti-nausea drugs (Zofran, Solu-Medrol, Droperidol, Metoclopramide + Fenactil, Torecan). Zofran caused the fewest number of side-effects, solu-medrol inhibited nausea and vomiting significantly, however it caused many side-effects such as flush on a face, restlessness, incitement and headaches. Torecan did not prevent patients from vomiting. The greatest number of side-effects was observed after droperidol and metoclopramide + fenactil treatment.
Ginekol Pol 1993 Sep
PMID:[Side effects of drug treatment for ovarian cancer after administration of antiemetic drugs]. 814 54

A survey over recent international developments to detect the irradiation treatment of foods is given, in particular the programmes of "ADMIT" (FAO/IAEA) and of BCR (European Community). The need to detect radiation treatment by analysing the food itself is desirable to check compliance with existing regulations, such as the enforcement of labelling and control of prohibition, to enhance consumer confidence in the correct application of radiation processing, and to protect consumers' freedom of choice between irradiated or unirradiated food products. Some larger collaborative studies on an international scale have already taken place, e.g. ESR measurements of bones from chicken, pork, beef, frog legs and fish, thermoluminescence of insoluble minerals isolated from herbs and spices, gas chromatographic analysis of hydrocarbons and alkylcyclobutanones derived from the lipid fraction of chicken and the microbiological DEFT/APC procedure for spices. These methods could soon be implemented in international standard protocols.
Z Lebensm Unters Forsch 1993 Sep
PMID:[International cooperation on the detection of irradiated food]. 823 15

Stroke volume (SV) and systolic time intervals (STI) were measured automatically using impedance cardiography signals (ICG) and compared with those obtained by pulsed-wave Doppler echocardiography using the apex approach. The comparison was made in 9 healthy male subjects, mean age 24.9 +/- 12.2 years, using recordings of 10 heart cycles simultaneously obtained by the two methods. During measurements the subjects rested in the supine position. There were no differences between mean values of SV determined by the two methods as well as between mean values of ejection time (ET) (p > 0.8 and p > 0.9, respectively). The pre-ejection period (PEP) estimated by ICG was 22 ms longer than that determined by echocardiography (p < 0.001). The relationship between SV values measured by impedance cardiography (SVA) vs those calculated by echocardiography (SVE) was found to be close to the line of identity in the range of measurements. The regression equation for SV was: SVA = 0.784.SVE + 15 (r = 0.69, p < 0.001, SEE = 10.7 ml). We conclude that automatic determination of SV and ET from ICG signals provides results comparable in absolute values with those obtained by the pulsed wave Doppler ultrasonocardiography using the apex approach for subjects remaining in the supine position.
J Physiol Pharmacol 1993 Sep
PMID:A comparison between the automatized impedance cardiography and pulsed-wave Doppler echocardiography methods for measurements of stroke volume (SV) and systolic time intervals (STI). 824 26

Linkage studies on familial adenomatous polyposis (FAP) reported so far suggest that FAP is a genetically homogeneous disease. Recently, we found that the putative gene for Turcot syndrome, an apparently autosomal recessive clinical variant of FAP, is not allelic to FAP. Here we describe another family, segregating for an autosomal dominant disease clinically indistinguishable from FAP but genetically not linked to the APC locus, adding further evidence for the occurrence of non-allelic heterogeneity of FAP. These observations have implications to the linkage-based genetic counselling of persons at risk for FAP especially when they are drawn from small families giving insufficient information.
Am J Med Genet 1993 Sep 15
PMID:Non-allelic heterogeneity of familial adenomatous polyposis. 825 23

Recent interest in PDP (parallel distributed processing) models is due in part to the widely held belief that they challenge many of the assumptions of classical cognitive science. In the domain of language acquisition, for example, there has been much interest in the claim that PDP models might undermine nativism. Related arguments based on PDP learning have also been given against Fodor's anti-constructivist position--a position that has contributed to the widespread dismissal of constructivism. A limitation of many of the claims regarding PDP learning, however, is that the principles underlying this learning have not been rigorously characterized. In this paper, I examine PDP models from within the framework of Valiant's PAC (probably approximately correct) model of learning, now the dominant model in machine learning, and which applies naturally to neural network learning. From this perspective, I evaluate the implications of PDP models for nativism and Fodor's influential anti-constructivist position. In particular, I demonstrate that, contrary to a number of claims, PDP models are nativist in a robust sense. I also demonstrate that PDP models actually serve as a good illustration of Fodor's anti-constructivist position. While these results may at first suggest that neural network models in general are incapable of the sort of concept acquisition that is required to refute Fodor's anti-constructivist position, I suggest that there is an alternative form of neural network learning that demonstrates the plausibility of constructivism. This alternative form of learning is a natural interpretation of the constructivist position in terms of neural network learning, as it employs learning algorithms that incorporate the addition of structure in addition to weight modification schemes. By demonstrating that there is a natural and plausible interpretation of constructivism in terms of neural network learning, the position that nativism is the only plausible model of acquisition can no longer be defended. Indeed, I briefly discuss a number of learning-theoretic reasons indicating that constructivist models so characterized uniquely possess a number of important learning characteristics.
Cognition 1993 Sep
PMID:Neural networks, nativism, and the plausibility of constructivism. 826 97

A HPLC Assay was developed to identify and measure the metabolite of acrylamide, mercapturic acid, N-Acetyl-s-(propionamide)-cysteine (APC) in urine. O-phthalaldehyde (OPA) was utilized as a precolumn derivatizing agent in the assay. This derivative was isolated with a good selectivity by high performance liquid chromatography (HPLC) employing reversed phase ODS columns. The quantitation of the mercapturic acid derivative was reproducible and with a detection limit of 1 pmol. The average coefficient of variation for the runs carried out on the same day was approximately 4.6% at the range of 80-160 mumol.L-1 of APC, and the mean analytical recovery from urine samples was 94%. The metabolite of urine of workers exposed to acrylamide was identified as N-acetyl-s-(propionamide)-cysteine by HPLC chromatography and fluorescence scan and HPLC-Mass spectra. All results were identical with the authentic synthesized compound.
Biomed Environ Sci 1993 Sep
PMID:Determination of acrylamide metabolite, mercapturic acid by high performance liquid chromatography. 829 72

Cellulose columns have been used to separate erythrocytes into deformability classes, but recoveries have been variable and incomplete. Columns of modified cellulose (propylaminocarbonylmethyl cellulose [PAC] and butylisourea cellulose [BIC]) were effective in increasing the recovery of both normal and sickle cells applied to the columns, with reasonable yields of rigid cells in the late fractions. In particular, sickle cells were recovered in 95% yield, and late eluting cells had a sharply reduced deformability index.
Exp Hematol 1993 Sep
PMID:Modified celluloses for erythrocyte deformability fractionation. 835 35

Carbohydrates are T cell independent antigens because they do not bind to MHC molecules. However, glycopeptides might potentially bind to MHC molecules via their peptide component for presentation to T cells. We have conjugated the disaccharide galabiose [Gal alpha (1-4)Gal beta] to the amino terminus of a T cell peptide determinant from hen egg-white lysozyme [HEL(52-61)]. The resulting glycopeptide (Gal2-52-61) and a nonglycosylated analogue containing tyrosine and glutamic acid at the amino-terminus (YE-52-61) bound equally well to purified I-Ak. T cell hybridomas were produced after immunization with Gal2-52-61. Many of the T cell hybridomas were glycopeptide-specific and responded to Gal2-52-61 but not to nonglycosylated synthetic peptides or to HEL presented by APC, indicating that the carbohydrate moiety influenced T cell recognition. Recognition was lost with the amino terminal attachment of the disaccharide to a peptide six amino acids longer at the amino terminus than HEL(52-61). Recognition also was lost with peptides containing only a single galactosyl residue or with galabiose bound to a different I-Ak binding peptide. T cells directed to Gal2-52-61 recognized glycopeptides having significant variation in the disaccharide structure, such as HEL(52-61) glycopeptides carrying lactose, cellobiose, or hepta-o-acetylated galabiose. Peptide residues were important features of the T cell epitope; Ala substitutions of two critical T cell contact residues of HEL(52-61) (Tyr53 and Leu56) abrogated T cell reactivity to the glycopeptides without affecting binding to I-Ak. In conclusion, we propose that these T cells recognize a peptide conformation specific to glycopeptide-I-Ak complexes and that this recognition does not involve specific interaction between the carbohydrate moiety and the T cell receptor.
J Immunol 1993 Sep 01
PMID:Glycopeptides bind MHC molecules and elicit specific T cell responses. 836 Apr 71

T lymphocytes are activated upon binding of their Ag receptors to a complex of Ag-derived peptides and MHC class I or class II molecules expressed on the surface of APC. It is now well established that APC degrade exogenous Ag in acidic endosomal compartments, and that Ag fragments bind to class II molecules moving through these compartments on their way to the surface of the APC. Although peptides derived from some endogenous Ag can also bind to class II molecules and subsequently be recognized by class II-restricted T cells, the intracellular trafficking pathways that enable endogenous proteins to be processed for association with class II molecules remain controversial. We have analyzed the mechanism by which the envelope (env) protein of the HIV-1 is processed in infected cells for recognition by class II-restricted T cells. A large number of env-specific class II-restricted human CTL clones were shown to lyse B-lymphoblastoid cell lines expressing the env. A novel dilutional assay proved that A novel dilutional assay proved that recognition of endogenous env protein was not a consequence of release and re-uptake of the env protein and subsequent processing by the standard class II-restricted pathway. Processing of endogenous env protein required that the protein be co-translationally translocated into the endoplasmic reticulum (ER) and then exit the ER, since the class II-restricted CTL did not recognize env protein localized to the cytosol or retained in the ER of target cells. Under these conditions, however, class I-restricted recognition was readily demonstrated. Finally, class II-restricted recognition was strikingly dependent upon the steady state level of surface env protein, since extracellular reagents that removed intact env protein from the surface of target cells inhibited recognition. This inhibition operated at the Ag-processing level rather than at the level of subsequent Ag recognition. These results provide the first direct evidence that endogenously synthesized membrane proteins enter the class II-restricted Ag-processing pathway after expression on the cell surface in an intact form.
J Immunol 1993 Sep 15
PMID:HIV-1 envelope protein is expressed on the surface of infected cells before its processing and presentation to class II-restricted T lymphocytes. 837 62


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