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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Incubation of CMP in 2H2O with 0.5M cysteine methyl ester at p2H 5 and 37 degrees C for 24 h resulted in 43% exchange of 5-H to 5-2H. No deamination of the cytosine nucleus was noted during this treatment. Native and denatured DNA samples from calf thymus were treated in 3H2O with cysteine methyl ester at pH 5 and 37 degrees C for 24 h and incorporation of tritium into each DNA base was determined by enzymic digestion of the treated DNA. The order of the specific radioactivity found was cytosine greater than guanine greater than adenine greater than thymine for denatured DNA and guanine greater than adenine approximately cytosine greater than thymine for native DNA. The ratio of radioactivity for denatured/native was 11.6 for cytosine, 1.5 for guanine, 1.8 for adenine and 1.1 for thymine. Hence the incorporation in cytosine under the reaction conditions is preferential for single-stranded, nonhelical regions of DNA. Escherichia coli glutamic acid tRNA II was treated in 3H2O with 1.24 M cysteine methyl ester at pH 5 and 37 degrees C. The 24-h-treated tRNA was digested with ribonuclease T1 and the fragments were fractionated. Each fragment was then digested with ribonuclease T2 into mononucleotides and the radioactivity distribution among the bases was determined. The average radioactivity found for each of the bases of the four major nucleotides was cytosine greater than guanine approximately adenine greater than uracil. The radioactivity in cytosine varied greatly among the RNase T1 fragments, the ratio of the highest to the lowest radioactivity being 18.7. The corresponding value for guanine was 11.1, for adenine 4.73 and for uracil 3.64. Based on the data obtained, it was deduced that in this tRNA the anticodon loop, the dihydrouridine loop and the extra loop were "exposed" under the conditions employed for the labeling. The 5'-terminal cytosine of the anticodon loop was in a "non-exposed" state, a situation similar to that previously reported for E. coli tyrosine tRNA [Cashmore, A. R., Brown, D. M. & Smith, J. D. (1971) J. Mol. Biol. 59, 359-373] and for E. coli formylmethionine tRNA [Goddard J. P.+Schulman L. H. (1972) J. Biol. Chem. 247, 3864-3867]. Both cytosine 48, located at the 3'-terminal of the extra loop, and guanine 15 in the dihydrouridine loop were in an "emposed" state. This finding does not agree with a tRNA model in which this pair of cytosine and guanine, commonly found in tRNA sequences, forms hydrogen bondings. Positions 30--32, 61--64 and 71, which are located in the stems, were found to be strongly "buried".
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PMID:Conformation of Escherichia coli glutamic acid tRNA II as studied by hydrogen-tritium exchange catalyzed by cysteine methyl ester. 0 69

Unmodified rejection of rat renal allografts was characterized by the early onset and rapid progression of endothelial damage in venules and capillaries which culminated in ischemic cortical necrosis. This pattern of endothelial injury correlated with lymphocyte accumulation in vascular lumens and could not be duplicated by renal perfusion with alloantibodies or prevented by C'3 depletion. In contrast, endothelial integrity and normal graft function were maintained over study intervals extending to 200 days when Brown Norway (BN) rat kidneys were transplanted into Lewis (Le) rat kidney recipients subjected to neonatal thymectomy or lymph drainage. Vascular lesions occurred when syngeneic thoracic duct lymphocytes were transfused into these recipients, but irreversible endothelial injury could be prevented by simultaneous injections of immune plasma. These findings indicate that the destruction of donor endothelium is mediated by thymus-dependent immune mechanisms which can be altered by thoracic duct drainage to promote indefinite survival of renal allografts across major histocompatibility loci.
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PMID:Pathogenesis of vascular injury in rejecting rat renal allografts. 1 42

Although both the T and B cells of the Lewis rat have immunoglobulin receptors for basic protein (BP) of myelin, and both cell types are required for antibody production to BP, the present results demonstrate that the T cells are the only cells required for the induction of experimental allergic encephalomyelitis (EAE). Both EAE and anti-BP were readily induced in thymectomized, irradiated Lewis rats reconstituted with normal thymus and bone marrow cells and challenged with BP in complete Freund's adjuvant. If the thymus cells were first treated with BP heavily labeled with 125I so as to eliminate (sucide) specific T cells, the recipients neither develop EAE nor produce antibody to BP. On the other hand, if the thymus cells were untreated and the specific B cells of bone marrow were eliminated by treatment with 125I-BP, EAE was not inhibited, although no antibody was produced. These results strongly suggest that the T cell is responsible for the induction of EAE although both the T and B cells are competent to respond to BP. Evidence was presented which suggests that neither suppressor T cells nor circulating antibody are involved in the inhibition of EAE by injection of Lewis rats with nonencephalitogenic preparations of BP. The immune status of T and B cells of the Lewis rat to BP was compared with the immune status of these cells in other species to thyroglobulin, where only the B cells appear to be competent. In this context, Brown Norway rats, which are resistant to the induction of EAE, also appear to lack T cells reactive to BP, although competent B cells are present.
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PMID:Cellular events in the induction of experimental allergic encephalomyelitis in rats. 6 Apr 61

Immune reactivity in lymhoid organs of rats during the last week of syngeneic (Lewis: L x L) or allogeneic (females Lewis x males Wistar: L x W) pregnancy was compared with that found in non-pregnant animals. The thymus weight was slightly reduced and the response of thymic lymphocytes to phytohaemagglutinin and concanavalin A was slightly, but not significantly, elevated in pregnant rats. By contrast, the response of lymphoid cells from spleen and mesenteric lymph nodes to the mitogens was reduced in rats during advanced pregnancy. The immune response of lymphocytes from pregnant L x W rats to allogenic (Brown-Norway: BN) or semiallogeneic (W) irradiated cells was tested by the mixed lymphocyte culture (MLC) assay. The MLC response of para-aortic lymph nodes towards the unrelated BN cells was elevated over that of non-pregnant rats on day 15 of pregnancy. No significant enhancement was observed at the same time in the MLC response of mesenteric lymph nodes. On day 20 of pregnancy, a reduced MLC response towards BN cells was found in the mesenteric and para-aortic lymph nodes. On day 15 of pregnancy, the MLC response of mesenteric and, more markedly, that of para-aortic lymph nodes to paternal (W) cells was enhanced, as compared to that of non-pregnant rats. On day 20 of pregnancy, the response of mesenteric lymph nodes was suppressed, while the response of para-aortic lymph nodes was similar to that found in non-pregnant rats. Since the latter lymph nodes are the most directly exposed to antigenic stimulation from the uterus, it seems unlikely that the suppression in response to T-cell mitogens observed in the spleen and mesenteric lymph nodes during pregnancy accounts for the survival of the foetus. It seems more plausible that local factors in the vicinity of the uterus protect the foetus from being rejected.
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PMID:Changes in immunological activity of rat lymphoid organs during pregnancy. 14 23

The lateral diffusion of integral glycoproteins of lymphocyte plasma membranes is not described only in terms of Brown movement. The development of immune process to the thymus-dependent antigene in vivo induces changes in physico-chemical state of ConA and immunoglobulin receptors of the surface of immuno-competent cells revealed when studying cap formation in vitro.
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PMID:[Lateral diffusion of the concanavalin A and immunoglobulin receptors on the surface of lymphocyte plasma membranes on exposure to antigen]. 31 21

The OK10 virus complex is known to contain two detectable viruses: a) focue-forming virus OK10V that transforms chick embryo cells, and b) an associated virus OK10AV present in excess that converts the morphology of cultured chick embryo cells. The pathogenesis of OK10 virus infection was studied, using 2--4 day old Brown Leghorn chickens. A group of chickens was sacrificed at weekly intervals, serum samples were taken and tissues were examined for virus. Autopsies of the chicken were performed and gross and microscopic changes were registered. After intraperitoneal injection of 10(4) focus-forming units of OK10 virus, infectious OK10AV was detected after one week in Bursa Fabricius, thymus and liver, and OK10V after two weeks in Bursa Fabricius but in no other organ. Neutralizing serum antibodies developed within three weeks. The first malignant changes, in the mesentery, were detected after three weeks. The infection was lethal in all experiments within 6--8 weeks. In the mesentery, the tumors consisted of large tumour cells with clear cytoplasm, a large nucleus and prominent nucleoli. The origin of these cells could not be established. The cells were surrounded by lymphoid cells. From the tumours, vontinuous cell lines were established which produced both viruses OK10V and OK10AV and had blast-like morphology. After intravenous injection of OK10 virus, tumours could also be found in liver, kidneys and testes. The associated virus OK10AV was injectious for chickens and induced neutralizing serum antibodies. One out of seven chickens died of leukosis after 1 1/2 years. The OK10 virus complex, consisting of a tumour-forming and a weakly oncogenic associated virus, appears to have a multiple oncogenic potential in its rapid oncogenic action in vivo.
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PMID:Rapid oncogenesis in vivo by chicken retrovirus OK10. 69 27

Tilorone is a synthetic amino-alkoxyfluorenone with demonstrated antiviral and antitumor properties. This study gives evidence for immunosuppressive properties of the substance as well. Buffalo rats (AgB6) received skin grafts from rats of the Fischer (AgB1) strain. Control animals rejected in 9.9 +/- 1.1 days, compared to 13.7 +/- 2.3 days for recipients treated with Tilorone. Steroids when combined with Tilorone further prolonged skin allografts to 16.7 +/- 2.6 days. Heart allografts from Fischer (AgB1) and Brown-Norway (AgB3) to Lewis (AgB1) also were performed. In the Fischer to Lewis combination, allograft survival was prolonged from 14.7 +/- 1.0 to 31.0 +/- 3.8 days. In the Brown-Norway to Lewis combination, treated rats rejected in 10.2 +/- 1.4 days versus 6.6 +/- 1.1 days for controls. Increased levels of cytotoxic antibody specific to lymphocytes of the donor strain were noted in Tilorone-treated animals. The mechanism by which Tilorone prolongs allografts may well involve a combination of interferon production and specific suppression of thymus-derived lymphocytes.
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PMID:Skin and heart allograft prolongation in tilorone-treated rats. 76 31

The action of HCS and HCG on cell-mediated immunity has been investigated. Full-thickness skin homografts were performed in 40 whole adult female Wistar rats. Brown rats of the A X C strain were selected as donors. The animals were divided into four groups injected with HCS, HCG, HCS + HCG, and saline. The graft rejection time and the wet and dry weight of thymus and spleen were evaluated. No hormonal treatment showed any effect on skin graft survival. Thymus weight, both wet and dry, decreased significantly by treatment with HCP or HCS + HCG. No modification was observed in spleen weight. These results do not agree with the theory that HCS and HCG modify immunological competence of maternal lymphocytes and thus may contribute to prevent rejection of the fetus.
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PMID:Effects of human chorionic somatomammotropin and human chorionic gonadotropin on skin homografts in rats. 80 Mar 86

The biphasic nature of the time course of the action of staphylococcal nuclease on thymus nucleohistone was confirmed by studying the hydrolysis of this nucleoprotein at various enzyme concentrations. The transition from the rapid first to the sluggish second phase of the time course was particularly distinct at the highest enzyme concentrations. The rapid initial phase of the hydrolysis curve leveled off sharply when between 60 and 65 per cent of the total TNH phosphorus had been converted to acid-soluble phosphorus compounds. The insoluble complexes of TNH with protamines were found to be very resistant against the action of staphylococcal nuclease. The time course of the action of staphylococcal nuclease on a commercial nucleoprotamine of salmon testicles was found to become very sluggish when between 35 and 40 per cent of its total phosphorus had been converted to acid-soluble phosphorus compounds. When nucleoprotamines prepared in the laboratory from the secreted sperm cell suspension of Brown Brook Trout were digested with staphylococcal nuclease, only between 15 and 20 per cent of the total phosphorus were cleaved to acid-soluble phosphorus compounds during the rapid phase of the nuclease action. The respective values for the phosphorus fractions available for magnesium-binding and those susceptible to the rapid cleavage by staphylococcal nuclease were found to be very similar.
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PMID:The action of staphylococcal nuclease (EC-number 3. 1. 4. 7.) on thymus nucleohistone (TNH) and on some nucleoprotamines. 112 11

To characterize and clarify the function of CD34 antigen experimentally, we isolated two types of CD34 mRNA from a cDNA library of murine stromal cell line, PA-6 stimulated with lipopolysaccharide (LPS) and 12-o-tetra-decanoylphorbol 13-acetate (TPA) using a human CD34 probe. In addition to the clone (open reading frame [ORF]:1149bp) reported by Brown et al, a novel clone (ORF:978 bp) was obtained. The difference between the two clones was in the cytoplasmic portion of CD34; the former has 73 amino acids, while the latter has 16. We investigated the genomic sequence of cytoplasmic portion and found conserved nucleotide sequences at the exon-intron junction (GT ... AG). Thus, it was concluded that alternative splicing gave two types of CD34 mRNA. A novel clone contains the longer cDNA, including a insert of 156 bp, but results in a shorter predicted coding sequence because of the introduction of an inframe stop codon. Northern blot analysis using a murine cDNA probe (HindIII fragment, 900 bp) showed that CD34 was highly expressed in the brain and testis, and moderately in the thymus, spleen, and bone marrow, but not in adult liver. However, day 12 to 14 fetal liver cells showed significant expression of CD34. Quantitative reverse transcription polymerase chain reaction showed that spleen, thymus, bone marrow, and testis RNA gave two bands of almost equal intensity, but in the brain a novel clone was expressed three times more than the other clone. Furthermore, Northern blot analysis using a probe (156 bp) specific for the spliced intracellular region confirmed the significant mRNA expression of a novel clone. Although the biologic significance of alternative splicing remains to be elucidated, it is suggested that a different carboxyterminal tail causes a change in signal transduction.
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PMID:Two types of murine CD34 mRNA generated by alternative splicing. 137 70


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