Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0153470 (Spleen)
 4,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Young male crossbred chicks were fed crystalline amino acid diets containing excess L-methionine or DL-homocysteine to evaluate factors causing methionine toxicity. Chicks were fed diets containing graded levels of excess methionine from 0% to 2.0%. Rate of gain was reduced at all levels of excess methionine, but the magnitude of depression was greater between 1% and 2% than between 0% and 1% excess methionine. Methionine accumulated in plasma of birds fed excess methionine, but plasma levels of homocysteine, cystathionine and cystine remained essentially unchanged. Spleen iron levels increased linearly and blood hemoglobin decreased linearly when chicks were fed diets containing greater than 1% excess methionine, a level equivalent to about 3 times the chicks' requirement. Chicks fed 1.36% homocysteine had reduced gain and gain:feed values, but spleen iron and hemoglobin levels were unchanged. 3-Methylthiopropionate, a possible metabolite in a proposed alternate pathway, caused a precipitous increase in spleen iron levels. Various methyl sources (betaine, choline, methyl acetate) when fed in excess failed to increase spleen iron levels. Methyl mercaptan and methyl mercaptoacetate likewise did not result in an increase in spleen iron deposition. Both the hemosiderosis condition and the reduced food utilization caused by excess methionine were reversed by supplemental glycine plus threonine.
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PMID:Factors affecting methionine toxicity and its alleviation in the chick. 66 Feb 99

There is now convincing evidence for the imposition of self tolerance by means of the clonal deletion of self-reactive T cells operating within the thymus. Since not all self components may be encountered there, the question must be asked whether tolerance can occur post-thymically. To test this, we and other investigators have used transgenic technology to direct expression of a known "nonself" gene to a given extrathymic tissue. No lymphocytic infiltration was ever seen in transgene-expressing tissues, even if the mice were given normal syngeneic (nontransgenic) spleen cells intravenously or were stimulated with H-2Kb spleen cells. Infiltration did, however, occur in irradiated transgenic recipients of H-2Kb immune spleen cells. In MET-Kb mice, this infiltrate diminished with time, raising the possibility that peripheral tolerance may even have been induced in immune cells. H-2Kb-bearing skin was accepted in young RIP-Kb mice but rejected in older mice, which had lost more than 75% of their beta cells as a result of the overexpression of H-2Kb. This loss of tolerance thus occurred when the concentration of the tolerogen, H-2Kb, fell below some critical threshold. Following in vitro stimulation, spleen cells from young RIP-Kb mice could not kill H-2Kb-bearing targets, but could respond to third party targets. Thymus cells, on the other hand, could be stimulated to kill both targets, clearly indicating that tolerance was not imposed intrathymically. Spleen cells from older RIP-Kb mice (those that had lost most of their beta cells) killed both targets, which is in agreement with the in vivo data. Reactivity to H-2Kb was restored to young spleen cells by providing them with IL-2. Two hypotheses were proposed to account for the above findings: tolerance results either from the deletion or functional silencing of high-affinity effector cells or of regulatory, IL-2-producing helper T cells. As it is difficult to distinguish between these, we have produced a second series of transgenic mice (F3+) with rearranged TCR genes encoding an anti-H-2Kb TCR and derived "double-transgenic" (F3+RIP+) offspring by mating these mice with RIP-Kb mice. The transgenic TCR utilized the V beta 11 segment which can be detected by a monoclonal antibody. There were in the thymus very few CD4+ and very few CD4+8+ cells in both F3+ and F3+RIP+ mice and, in the double-transgenic mice, there was no evidence of deletion of CD8+V beta 11+ cells in the periphery although they showed tolerance to H-2Kb-bearing skin.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:A transgenic approach to the study of peripheral T-cell tolerance. 193 38

Spleen mononuclear cells of BALB/C mice and YAC-1 cells were used in this experiment. Leucine enkephalin or methionine enkephalin at time 0 was added to cell cultures and the amount of the enzyme lactate dehydrogenase released from lysed target cells was determined 22 hours after incubation. There were on average 41% (5% to 60.7%) and 63% (46.8% to 78%) enhancements of natural killer activity in the presence of leucine enkephalin (1 x 10(-11)-1 x 10(-3) mg/ml) and methionine enkephalin (1 x 10(-15)-1 x 10(-3) mg/ml) respectively. The results showed that opioid peptides can modify NK cell function.
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PMID:[Effects of the enkephalins on natural killer cytotoxicity]. 215 Dec 67

Spleen cells, peripheral lymphocytes, and soleus muscles were removed from male Sprague-Dawley rats that had been run on a treadmill (24 m/min) for either 20, 40, or 60 min or to exhaustion (86 +/- 41 min) and were labeled in vitro with [35S]methionine at 37 degrees C. Similar tissues from nonrunning control rats were labeled in vitro at either 37 or 43 degrees C (heat shock). Fluorographic analyses of one- and two-dimensional polyacrylamide gel electrophoretic separations of the proteins from cells and tissues of exercised rats demonstrate the new or enhanced synthesis of proteins of approximately 65, 72, 90, and 100 kDa. Although synthesis of these proteins is low or not detectable in tissues from control rats labeled at 37 degrees C, they are prominent products of similar tissues labeled under heat-shock conditions (43 degrees C) and, in fact, correspond in Mr and pI with the so-called heat-shock proteins. These results suggest that exercise is a sufficient stimulus to induce or enhance the synthesis of heat shock and/or stress proteins in mammalian cells and tissues.
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PMID:Exercising mammals synthesize stress proteins. 218 42

Murine monoclonal antibodies against human/rat corticotrophin-releasing factor-41 (CRF-41) were produced and characterized for use in the immunological and biological characterization of CRF-41. Spleen cells from BALB/c mice immunized with CRF-41 conjugated to bovine gamma-globulin were fused with a BALB/c-derived non-secretor X-63 myeloma line. Hybridomas were selected for CRF antibody production by enzyme-linked immunosorbent assay, and positive hybridomas cloned twice. Three monoclonal antibodies were obtained (KCHMB001, KCHMB002 and KCHMB003) and characterized as IgG1, IgG1 and IgG2a isotypes respectively, with affinity constants for rat CRF-41 of 30, 53 and 34 nmol/l respectively. All three monoclonal antibodies recognize an epitope contained between residues 34 and 41 of the human/rat sequence. The antibodies were able to neutralize the ACTH-releasing activity of rat CRF-41, applied to rat pituitary fragments in vitro, in a dose-dependent manner. Isoelectric focusing showed that KCHMB003 detected bands of synthetic rat CRF-41 and rat [Met(O)21,38]-CRF-41 at pH 7.1 and 6.8 respectively. Use of KCHMB003 in a two-site enzyme-amplified immunoassay showed that this antibody recognizes both synthetic rat CRF-41 and immunoreactive CRF-41 in rat hypothalamic tissue extracts.
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PMID:Production and utilization of monoclonal antibodies to human/rat corticotrophin-releasing factor-41. 224 88

Bovine pancreatic trypsin inhibitor (BPTI, also known as aprotinin or Kunitz inhibitor, a mini-protein composed of 58 amino-acid residues, containing a single methionine residue at position 52) has been selectively oxidized by treatment with chloramine T, under mild conditions, to the methionyl sulfoxide derivative. Spleen inhibitor II (SI II, an isoform of BPTI containing two methionine residues at positions 18 and 52) has been oxidized under the same conditions. Oxidation affects the functional properties of the two inhibitors differently: the antiproteolytic activity of BPTI towards bovine trypsin and chymotrypsin, porcine kallikrein and human leukocyte elastase is not changed upon oxidation, while in the oxidized SI II, the affinity for both chymotrypsin and elastase decreases, with respect to the native protein. These results have been directly related to the oxidation of Met18 in SI II, located at the P'3 site in the contact area with the proteases.
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PMID:Selective oxidation of methionine residues in Kunitz-type protease inhibitors. 247 60

We have compared the levels of DNA methyltransferases from rat liver and spleen in both sexes following a single injection of N-2-acetylaminofluorene (AAF). Enzyme extracts from treated animals were obtained at different intervals (2-34 days) after treatment. The extracts were assayed in the presence of chicken erythrocyte DNA and S-adenosyl-L-[Me-3H]methionine. A 55% increase in male rat-liver methyltransferase activity measured by Me-3H incorporation into DNA occurred on day 14. By contrast, female methyltransferase after a similar period revealed a 33% decrease in activity. Between days 21 and 34, there is a progressive return to normal methyltransferase levels. Spleen-derived enzyme studied between days 7 and 14, showed a decrease in methylating activity in both sexes. After replacing corn seed oil by ethanol as the vehicle for AAF injection, we observed a change in liver methyltransferase 48 h after injection. Quantification of radioactive eluates in m5C fractions together with the increase in the integrated area identified as m5C in HPLC chromatograms allowed positive identification of methylated products.
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PMID:Changes in DNA methyltransferase induced by treatment with N-2-acetylaminofluorene. 281 14

Spleen cells from BALBc mice immunized with human epidermoid carcinoma A431 cells were fused with mouse myeloma P3NP cells. One of the isolated hybridoma lines, B4G7, secreted a monoclonal antibody of the IgG class which inhibited the binding of [125I]-EGF to A431 cells and human fibroblasts, but not to mouse 3T3 cells. This inhibition was partial (65-70%) and Scatchard analysis of the EGF binding data suggested that the B4G7 antibody interacts preferentially with a low-affinity class of EGF receptors. This monoclonal antibody specifically precipitated EGF receptors (Mr = 170,000 and 155,000) of A431 cells which were directly crosslinked with [125I]-EGF. It also precipitated EGF receptors from cells whose surface proteins were labeled with 125I, from cells grown in the presence of [35S]-methionine or [32P]-orthophosphate, and from membrane fractions phosphorylated in vitro with [32P]-gamma-ATP. Receptors subjected to EGF-induced phosphorylation, both in vivo and in vitro, were also precipitated. The B4G7 antibody blocked approximately 70% of the EGF receptors in human fibroblasts, but did not stimulate DNA synthesis in these cells. However, in the presence of this antibody, cells showed the full mitogenic response to EGF, presumably through the unblocked receptors that are likely to be of the high-affinity type.
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PMID:Monoclonal antibody that immunoreacts with a subclass of human receptors for epidermal growth factor. 299 89

Antibodies to molybdate-stabilized chicken oviduct progesterone receptor were raised in a Wistar rat and detected by interaction with homogeneous radioiodinated progesterone receptor. Spleen cells of this rat were then fused with mouse Sp2/0-Ag14 myeloma cells and the antibodies produced by the hybrid cells were detected by double immunoprecipitation using the 125I-labeled receptor. Cells of one of the positive cultures were then cloned by limiting dilution and one hybridoma cell line was studied. The monoclonal antibody produced was an IgG2b, and it reacted with the molybdate-stabilized "8-9S" form of the chicken oviduct progesterone receptor, labeled with either [3H]progesterone or [3H]ORG 2058 (a high-affinity synthetic progestin). Kd for the 8-9S progesterone receptor was approximately equal to 1 nM. Progesterone receptor-monoclonal antibody complexes were labeled with radioactive progesterone, suggesting that antibody does not prevent hormone binding. By using a [35S]methionine-labeled antibody, we were able to detect the progesterone receptor independently of its characteristic function of binding radioactive hormone. No crossreaction with human progesterone receptor was detected.
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PMID:Monoclonal antibody to chicken oviduct progesterone receptor. 657 54

Two alternate screening methods have enabled the detection of monoclonal antibodies with different specificities toward the lysosomal enzyme alpha-mannosidase of Dictyostelium discoideum. Spleen/myeloma hybrid cell cultures were screened for antibody production by separate assays: an indirect enzyme-linked immunoadsorbent assay (ELISA) based on the antibody binding to enzyme adsorbed on plastic, and a direct assay of the antibodies' ability to precipitate enzyme activity with fixed Staphylococcus aureus cells (Pansorbin). Fourteen stable antibody-producing cell lines resulted from a single fusion; these fell into three distinct classes based on their screening characteristics. A group of eight were positive in both assays, and these immunoprecipitated a 140,000 Mr precursor form of alpha-mannosidase in addition to the 58,000 and 60,000 Mr mature enzyme subunits from [35S]methionine-labeled total secreted protein preparations. Two of the antibodies were positive only in the immunoprecipitation assay; these failed to precipitate the 140,000 Mr precursor. The third class consisted of four antibodies that were positive only in the ELISA method. These exclusively recognized an altered conformation of the enzyme (precursor and mature forms) that was immobilized either on plastic or on nitrocellulose paper. In addition, only members of this class were able to bind to immobilized fragments of protease-treated enzyme. The implications of these findings for the general design of monoclonal antibody screenings and for the alternative structures of this enzyme are discussed.
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PMID:Functional heterogeneity of monoclonal antibodies obtained using different screening assays. 667 Jul 43


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