Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P30536 (PBS)
 9,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin-like growth factor I (IGF-I) is present in multiple tissues and cell types. Expression of the IGF-I gene was examined in GH3 cells, a rat pituitary tumor cell line secreting GH and PRL. Increasing concentrations of RNA extracts of GH3 cells yielded a linear increase in hybridization intensity with a 32P-labeled mouse IGF-I cDNA probe. Northern analysis of GH3 cells poly(A) RNA revealed IGF-I mRNA transcripts 1.3, 5.3, and 7.7 kilobases in size. Poly(A) RNA extracts of BALBc/3T3 fibroblasts, a cell line dependent on exogenous somatomedins for DNA synthesis, and of JEG-3 cells, a choriocarcinoma cell line, did not hybridize with the IGF-I cDNA probe. GH3 cells showed positive immunoperoxidase staining using a rabbit anti[Thr59]IGF-I antibody which was largely blocked by prior incubation of the antibody with excess IGF-I. Negligible background peroxidase activity was present in cells incubated with a rabbit nonimmune serum and PBS. Furthermore, BALBc/3T3 fibroblasts showed only weak specific staining with the IGF-I antibody. Finally, GH3 cells secreted IGF-I into the culture medium in a time-dependent fashion, while neither 3T3 nor JEG-3 cells produced detectable medium levels of the peptide after 72 h of incubation. As IGF-I is known to inhibit GH production by the pituitary, the data shown suggest that locally produced IGF-I may regulate GH secretion in an autocrine or paracrine fashion.
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PMID:Insulin-like growth factor I gene expression in GH3 rat pituitary cells: messenger ribonucleic acid content, immunocytochemistry, and secretion. 355 29

Thermal transition profiles were recorded for a variety of natural and synthetic DNA and double-stranded RNA preparations in the presence of tetramethylammonium (TMA+) and tetraethylammonium (TEA+) cations. Double-stranded RNAs of natural origin, with GC contents of 50% exhibited the same profiles and Tm values as native DNA containing normal bases. Hence the tetraalkylammonium cations liquidate not only the effects of base composition, and the difference in stability between A-T and A-U base pairs (further confirmed by measurements with uracil-containing DNA from phage PBS-2), but also that of the 2'OH. In the presence of TMA+ cations, there is very marked enhancement of the stability of U-U base pairs in poly(rU) and poly(Um). In 2.4 M TEA, the 1:1 complex of poly(G) with poly (C) formed readily and melted reversibly with a Tm as low as 87 degrees C. At concentrations of TMA and TEA for which dTm/dXGC = 0, the Tm values for various phage DNA preparations containing atypical bases (phages T2, T4, phi e, phi W-14, PBS-2) differ appreciably from those with 'normal bases'. Analysis of these findings indicates that the selective interaction of TMA and TEA cations with A-T base pairs occurs in the minor groove of the DNA helix. The overall results show that the action of these quaternary ammonium cations is not due exclusively to preferential binding to A-T base pairs, but must involve other factors, including modifications of solvent structure. They also underline the utility of TMA and TEA solvent systems for placing in evidence transition profiles not accessible in other solvent systems.
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PMID:The effects of tetraalkylammonium salts on helix-coil transition parameters in natural and synthetic ribo- and deoxyribo-polynucleotides. 615 17

In 2 radioimmunoassays in use to detect antibodies to dsDNA, the Farr assay and the PEG assay, we observed inhibitory effects of normal human serum (NHS) on the DNA binding by SLE sera. This was found to be due by the fact that, during incubation at 37 degrees C, CO2, introduced in the incubation mixture by the serum, evaporates from the mixture. This results in increase in pH to values well above pH 8.0, which in turn leads to a decreased DNA binding by antibody. When SLE sera are tested at low dilution, this phenomenon may lead to false negative results. Proper pH control, by the use of buffers with a greater buffering capacity than PBS, completely prevented the observed inhibitory effects. However, under these conditions NHS bound significant amounts of DNA in both assays. The non-specific DNA binding by NHS was found to be heat-stable, but could be eliminated either by aerosil treatment of the sera or by addition of dextran sulphate to the incubation mixture. Lipoproteins and, to a lesser extent, the complement component C1q appear responsible for this non-specific binding. To avoid false negative results with SLE sera as well as non-specific binding by NHS, we propose the use of stronger buffers in combination with added dextran sulphate to the incubation mixture in both the Farr assay and the PEG assay.
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PMID:Influence of pH on the detection of low- and high-avidity anti-dsDNA. 618 61

PBS-2 phage DNA, which contains uracil in place of thymine, was used as substrate for both purified B. subtilis uracil-DNA glycosylase and a crude extract from M. luteus. Addition of [3H]5-azacytidine to the medium after phage infection resulted in substitution of 1.2% azacytosine for cytosine in DNA. Substrate DNA was also labeled with [14C]uracil. Neither enzyme preparation released tritiated bases from DNA. Analysis by S1 nuclease digestion show no increase in single-strandedness of the modified DNA. Enzymic release of uracil by the M. luteus extract was reduced by about 50% from the substituted substrate. By contrast, the rate of uracil excision by the purified enzyme was unaffected by the presence of DNA 5-azacytosine.
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PMID:Effects of 5-azacytosine in DNA on enzymic uracil excision. 620 64

Bacillus subtilis strains possessing the trpE30 marker (splitting of the trpE locus and a non-tandem duplication of chromosome segment Ib: purB-tre) when transformed or transduced to tryptophan independence mainly give rise to haploid cells with the genetic structure of strain 168. However, among the Trp+ transformants or transductants about 10% are merodiploid carrying a non-tandem duplication of segment C (trpE-ilvA) while maintaining that of segment Ib. Linkage and segregation studies made it possible to determine their genetic structure, which can be represented by three different maps. In map a the copies of Ib are inverted repeats and one of them is flanked by two direct repeats of segment C; in map b two Ib-C segments are inverted repeats and in map c the copies of C are inverted repeats with one of them flanked by direct repeats of Ib. It is proposed that transition from map a to map b and then to map c, and vice versa, may occur by recombination between inverted repeats of either Ib or C. The merodiploids are unstable, recombination between direct repeats leading to haploid cells of 168-type structure. The models proposed for merodiploid formation call for fusion of two recipient chromosomes mediated by the donor segment and recombination between copies of a DNA sequence of the two chromosomes located in different regions. In the case of PBS-1 mediated transduction the greater length of the donor DNA segment makes it possible to obtain the merodiploids with a single recipient chromosome and this needs only a slight modification of the models. No trpE30+ merodiploids are found in transformation when the recipient carries a deletion of the SP beta prophage, or in transduction when both donor and recipient possess this deletion. These results indicate that the homologous sequences involved may be part of the SP beta prophage or that a sequence of bacterial DNA has a good homology with it.
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PMID:Bacillus subtilis strains carrying two non-tandem duplications of the trpE-ilvA and the purB-tre regions of the chromosome. 640 84

There have been no reported studies on the Feulgen-DNA cytofluorometry of the cartilage cells. We have attempted to devise a method of cell separation from the epiphyseal and articular cartilages of the rats, and to analyze by cytofluorometry the changes in the ploidy patterns of these chondrocytes during growth and ageing of the animals. Chondrocytes were isolated from the proximal cartilage of tibia by dual enzymatic digestions of the cartilage matrix with papain and collagenase, followed by mechanical cell separation with scissors and a micro-homogenizer, and were smeared onto the object glass with PBS. These procedures were found to be suitable for the Feulgen-DNA cytofluorometry of the chondrocytes from our repeated studies. We also carried out Feulgen-DNA cytofluorometry combined with 3H-thymidine autoradiography to determine cellular DNA content of the DNA synthetic chondrocytes in the epiphyseal cartilage. It has been clarified that during the growth course of the rats, the chondrocytes of the epiphyseal cartilage consist of many mononuclear diploid cells, a few mononuclear tetraploid cells and of some fraction of the cells having intermediate DNA values between the diploid and tetraploid levels. Those cells with intermediate DNA values, after autoradiographic studies, were found to correspond to DNA synthetic cells, indicating cell proliferative activity. It has been shown that during ageing of the rats, most of the chondrocytes from the articular cartilage are mononuclear diploid cells. The distribution of each cellular DNA content at the diploid level as determined by Feulgen-DNA cytofluorometry was shown to become gradually broader.
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PMID:[Quantitative analysis of nuclear DNA of rat chondrocytes during the course of growth and aging--Feulgen-DNA cytofluorometry method]. 665 20

With the immunofluorescence technique (IFT) using Crithidia luciliae as a substrate, 14,417 sera sent to our laboratory for routine anti-dsDNA determination, were screened for the presence of antibodies to dsDNA. The 1,260 sera that were found IFT positive were then assayed with the Farr radioimmunoassay, in which 3H-labelled PM2-DNA is used as antigen. Only 470 sera (37%) were found to be Farr positive. This discrepancy is, at least partially, caused by the fact that the Farr assay does not detect anti-DNA of low avidity, whereas the Crithidia-IFT does. Sixty-eight percent of the IFT-positive/Farr negative sera were found positive with the PEG assay, a radioimmunoassay that also employs double stranded PM2-DNA as antigen, and that also detects anti-dsDNA of low avidity. The IFT performed on IFT positive/Farr negative sera was found to be rather irreproducible. It was shown that this was due to local increases of the salt concentration resulting from the way the assay was performed. The problem could be overcome by careful control of the assay conditions, i.e. never letting Crithidia slides dry up after washing with PBS. In the PEG assay, these sera sometimes showed a DNA binding that decreased with time. It could be shown that this is caused by a parallel increase in pH during the incubation as a result of CO2 evaporation from the serum.
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PMID:Measurement of low avidity anti-dsDNA by the Crithidia luciliae test and the PEG assay. 675 23

In order to investigate whether defective phages of Bacillus subtilis killed sensitive bacteria by a lysis from without mechanism, the minimal number of phages required for killing was determined. This figure was found to vary with the m.o.i., giving a value of 1 on extrapolation to an m.o.i. of 0. This excluded lysis from without as the only killing mechanism, although it might play a role at high m.o.i.s. This was confirmed by experiments on leakage of ATP and u.v.-absorbing material, the uptake of oxygen and the effect of the phages on the membrane potential. Apart from a short, initial leakage of ATP, the cell membrane was not affected at low m.o.i.s. These results lead to the conclusion that at low m.o.i.s. the phages acted on a cytoplasmic component. Treatment of defective phages for 10 min at pH 2.5 resulted in breakdown of the phages without complete abolition of the killing activity. The active component, which was shown not to be DNA, could not be isolated from the mixture, but SDS gel electrophoresis of PBS X and a non-killing mutant of this phage suggested that a protein with a mol. wt. of 85000 was involved in killing.
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PMID:Effect of defective phages on the cell membrane of Bacillus subtilis and partial characterization of the phage protein involved in killing. 679 49

Human lymphocytes were exposed to UV-radiation and X-rays. The previously reported synergistic effect on the frequency of chromosome aberrations (Holmberg and Jonasson, 1974) was measured as a function of the time between the 2 irradiations to study the effect of repair processes in cells in PBS at 20 degrees C. The synergistic effect was found to be rather constant as a function of time (in the interval up to 90 min) when the UV-radiation is delivered first. The synergistic effect decreases with a half-life of about 20 min when the cells are first X-irradiated and after various times are given a UV-treatment. This is not in accordance with findings from dose-fractionation experiments with X-rays, in which lesions interact with each other for several hours. It is proposed that the enhanced aberration frequency in the combined irradiations originates from interactions between short-lived, X-ray-induced DNA-lesions in close spatial proximity (mainly lesions in the same ionization track), and the repair of these lesions are affected by the UV-treatment. In contrast, the aberrations studied in dose-fractionation experiments, by definition, are due to interactions between (long-lived) lesions in different tracks. Further details of this model for aberration production are discussed.
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PMID:The repair of chromosome aberrations in human lymphocytes after combined irradiation with UV-radiation (254 nm) and X-rays. 683 61

Phage PBS-2 DNA, which contains uracil in place of thymine, was selectively damaged and then used as substrate for purified Bacillus subtilis uracil-DNA glycosylase. This enzyme releases uracil from DNA in a limited processive manner. Irradiation by ultraviolet light (greater than 305 nm) in the presence of isopropanol and a free radical photoinitiator introduced covalently bound 8-(2-hydroxy-2-propyl)purines into DNA. Methylation by dimethylsulfate yielded 7-methylguanine. Apurinic sites were produced by gentle heating of methylated DNA. Rates of enzymic release of uracil from DNA varied among these three substrates. The Vmax was markedly decreased for DNA containing 8-(2-hydroxy-2-propyl)purines and apurinic sites but was unaffected by the presence of larger quantities of 7-methylguanine. This suggests that certain types of damaged DNA moieties may decrease the capacity for uracil excision. Therefore, interference with enzymic excision of this potentially mutagenic base may constitute a common mechanism of action of the reaction products of several unrelated DNA damaging agents.
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PMID:Perturbations of enzymic uracil excision due to purine damage in DNA. 695 98


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