Littérature scientifique sur le sujet « CA repeat DNA »
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Articles de revues sur le sujet "CA repeat DNA"
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Al-Ajmi, Kawthar, Shyam S. Ganguly, Adil Al-Ajmi, Zahid Al Mandhari et Mansour S. Al-Moundhri. « Insulin-Like Growth Factor 1 Gene Polymorphism and Breast Cancer Risk among Arab Omani Women : A Case-Control Study ». Breast Cancer : Basic and Clinical Research 6 (janvier 2012) : BCBCR.S9784. http://dx.doi.org/10.4137/bcbcr.s9784.
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Breast cancer is the most common cancer worldwide with significant global burden. Insulin-like growth factor 1 (IGF1) is an important regulator of cellular growth, differentiation, and apoptosis and mitogenic and antiapoptotic activities. Some studies suggested an association between cytosine adenine (CA) repeats gene polymorphisms of IGF1 and the risk of developing breast cancer while other studies did not find such an association. This study aims investigate the role of IGF1 (CA) repeats gene polymorphisms in the risk of developing breast cancer among Omani women. Methods We analyzed (CA) repeats gene polymorphisms of IGF1 by extraction of genomic DNA from the peripheral blood of 147 patients with breast cancer and 134 control participants and performed genotyping using DNA sequencing. Results Approximately 46% of patients carried the IGF (CA)19 repeat allele, with 31.3% carrying two copies of this allele and 50% of controls carried the IGF (CA)19 repeat allele with 30.1% carrying two copies of this allele. The difference of the IGF CA repeat groups was significant between cases and controls with ( P = 0.02). In contrast, there was no difference in the distribution of (CA)19 repeat allele, (CA)18 repeat allele and (CA)19 repeat allele between cases and controls. The difference of the CA groups was significant between cases and controls among postmenopausal women with ( P = 0.026), whereas no difference was observed among postmenopausal subjects ( P = 0.429). In both pre- and postmenopausal groups there was no difference in the distribution of (CA)19 repeat allele, (CA)18 repeat allele and (CA)20 repeat allele between patients and control subjects. On further IGF1 genotypes classification, we found an association between progesterone receptor status and the genotypes group where the non carrier of (CA)19 repeat group was compared to (CA)19 repeat carrier group (OR = 2.482; 95% CI = 1.119–5.503; P value = 0.023). Conclusion Overall there was no association between the IGF (CA)19 repeat and breast cancer in Omani females.
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Han, S. W., T. Y. Kim, K. W. Lee, D. Y. Oh, S. H. Lee, D. W. Kim, D. H. Chung, S. A. Im, D. S. Heo et Y. J. Bang. « EGFR mutation and intron 1 CA repeat polymorphism as predictive markers of gefitinib responsiveness in non-small cell lung cancer (NSCLC) ». Journal of Clinical Oncology 24, no 18_suppl (20 juin 2006) : 7173. http://dx.doi.org/10.1200/jco.2006.24.18_suppl.7173.
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7173 Background: EGFR mutation is significantly associated with objective response and prolonged survival in NSCLC patients treated with gefitinib. However, presence of mutant nonresponses and nonmutant responses mandates investigation of other molecular markers for more effective prediction of gefitinib sensitivity in NSCLC. It is unclear whether low CA repeat number in EGFR intron 1 has such a predictive role. Methods: Advanced NSCLC patients received gefitinib 250mg/day. EGFR mutation in exons 18 - 21 were identified by direct sequencing of PCR products of DNA extracted from archival paraffin embedded tissue. Number of CA repeat in intron 1 of EGFR was determined by GeneScan with tumoral DNA. Baseline characteristics, mutational status, CA repeat number and efficacy of gefitinib were analyzed in respect to each other. Results: To date, 73 patients were evaluable for EGFR mutation, CA repeat and gefitinib responsiveness. 14 patients (19.2%) harbored EGFR mutation (7 deletion in exon 19, 4 L858R, 1 L861Q, 1 G719A, and 1 insertion in exon 20). Most common CA repeat genotype was 20/20 repeat (31 patients) followed by 16/20 repeat (15 patients). Patients were classified as having either low CA repeat (sum of both allele ≤ 37 repeats) or high CA repeat (≥ 38 repeats). 34 patients (46.6%) had low repeat, whereas 39 patients (53.4%) had high repeat. Patients with EGFR mutation showed better objective response (response rate [RR] 57.1% vs. 10.2% in wild type [WT], p < 0.001), time-to-progression (TTP) (p = 0.031, median 5.1 vs. 1.9 months in WT), and overall survival (OS) (p = 0.051, median14.5 vs. 7.4 months in WT). In the whole study population, low CA repeat was not associated with RR (p = 0.38), TTP (p = 0.15), or OS (p = 0.51). However, in the 59 patients without an EGFR mutation, patients with low CA repeat tended to have better objective response (RR 17.2% [5/29] in low repeat vs. 3.3% [1/30] in high repeat, p = 0.10) and significantly better TTP (p = 0.019, median 2.2 months in low repeat vs. 1.2 months in high repeat). Conclusions: Our results suggest that low number of CA repeats in EGFR intron 1 may have possible role in prediction of gefitinib responsiveness when analyzed together with EGFR mutational status. [Table: see text]
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Chhatbar, Kashyap, John Connelly, Shaun Webb, Skirmantas Kriaucionis et Adrian Bird. « A critique of the hypothesis that CA repeats are primary targets of neuronal MeCP2 ». Life Science Alliance 5, no 12 (19 septembre 2022) : e202201522. http://dx.doi.org/10.26508/lsa.202201522.
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The DNA-binding protein MeCP2 is reported to bind methylated cytosine in CG and CA motifs in genomic DNA, but it was recently proposed that arrays of tandemly repeated CA containing either methylated or hydroxymethylated cytosine are the primary targets for MeCP2 binding and function. Here we investigated the predictions of this hypothesis using a range of published datasets. We failed to detect enrichment of cytosine modification at genomic CA repeat arrays in mouse brain regions and found no evidence for preferential MeCP2 binding at CA repeats. Moreover, we did not observe a correlation between the CA repeat density near genes and their degree of transcriptional deregulation when MeCP2 was absent. Our results do not provide support for the hypothesis that CA repeats are key mediators of MeCP2 function. Instead, we found that CA repeats are subject to CAC methylation to a degree that is typical of the surrounding genome and contribute modestly to MeCP2-mediated modulation of gene expression in accordance with their content of this canonical target motif.
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Ishimitsu, Toshihiko, Kazuyoshi Hosoya, Kohju Tsukada, Junichi Minami, Megumi Teranishi, Mayumi Saitoh, Miki Nakamura, Yasuo Futoh, Hidehiko Ono et Hiroaki Matsuoka. « Microsatellite DNA Polymorphism of Human Adrenomedullin Gene in Normotensive Subjects and Patients with Essential Hypertension ». Hypertension 36, suppl_1 (octobre 2000) : 715. http://dx.doi.org/10.1161/hyp.36.suppl_1.715-a.
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P121 Objective: Adrenomedullin (AM) is a hypotensive peptide widely produced in the cardiovascular organs and tissues such as the heart, kidney and the vascular cells. We investigated the association between DNA variations in AM gene and the predisposition to essential hypertension. Methods: We have cloned and sequenced the genomic DNA encoding human AM gene, and determined that the gene is located in the short arm of chromosome 11. The 3’-end of the gene is flanked by the microsatellite marker of CA repeats. Genomic DNA was obtained from the peripheral leukocytes of healthy normotensive subjects (NT; 179 men and 100 women, 57±6 years) aging 50 years or more and patients with essential hypertension (EH; 162 men and 98 women, 53±11 years) who had developed hypertension before the age of 50 years. The genomic DNA was subject to PCR using a fluorescence-labeled primer, and the number of CA repeats were determined by poly-acrylamide gel electrophoresis. Plasma AM concentration was measured by RIA and compared with respect to the number of CA repeats adjacent to the AM gene. Results: The averaged blood pressure was 117±13/73±9 mmHg in NT and 170±23/104±12 mmHg in EH when the patients were not treated. In Japanese, there existed four types of allelles with different CA-repeat number; 11, 13, 14 and 19. The frequencies of these alleles were 11: 28.7%, 13: 33.6%, 14: 34.7% and 19: 3.0% in NT and 11: 30.5%, 13: 28.4%, 14:34.3% and 19: 6.8% in EH. Thus, the frequency of 19 CA repeat allele was higher in EH than in NT (χ 2 =10.25, p<0.02). Namely, 13.5% of EH carried the 19-repeat allele, while the frequency was 6.1% in NT (χ 2 =8.43, p<0.004). In NT, plasma concentrations of AM in 21 homozygotes of 11-repeat allele, 27 homozygotes of 13-repeat allele, 30 homozygotes of 14-repeat allele and 17 heterozygotes carrying 19-repeat allele were 7.5±1.0, 7.0±1.3, 7.2±1.3 and 7.3±1.7 fmol/ml, respectively, and the values were not significantly different between the genotypes. Conclusion: Microsatellite DNA polymorphism of AM gene may be associated with the genetic predisposition to EH, although the gene expression is not likely to be affected by the genotypes.
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Murray, A. W., T. E. Claus et J. W. Szostak. « Characterization of two telomeric DNA processing reactions in Saccharomyces cerevisiae ». Molecular and Cellular Biology 8, no 11 (novembre 1988) : 4642–50. http://dx.doi.org/10.1128/mcb.8.11.4642-4650.1988.
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We have investigated two reactions that occur on telomeric sequences introduced into Saccharomyces cerevisiae cells by transformation. The elongation reaction added repeats of the yeast telomeric sequence C1-3A to telomeric sequences at the end of linear DNA molecules. The reaction worked on the Tetrahymena telomeric sequence C4A2 and also on the simple repeat CA. The reaction was orientation specific: it occurred only when the GT-rich strand ran 5' to 3' towards the end of the molecule. Telomere elongation occurred by non-template-directed DNA synthesis rather than any type of recombination with chromosomal telomeres, because C1-3A repeats could be added to unrelated DNA sequences between the CA-rich repeats and the terminus of the transforming DNA. The elongation reaction was very efficient, and we believe that it was responsible for maintaining an average telomere length despite incomplete replication by template-directed DNA polymerase. The resolution reaction processed a head-to-head inverted repeat of telomeric sequences into two new telomeres at a frequency of 10(-2) per cell division.
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Murray, A. W., T. E. Claus et J. W. Szostak. « Characterization of two telomeric DNA processing reactions in Saccharomyces cerevisiae. » Molecular and Cellular Biology 8, no 11 (novembre 1988) : 4642–50. http://dx.doi.org/10.1128/mcb.8.11.4642.
Texte intégralRésumé :
We have investigated two reactions that occur on telomeric sequences introduced into Saccharomyces cerevisiae cells by transformation. The elongation reaction added repeats of the yeast telomeric sequence C1-3A to telomeric sequences at the end of linear DNA molecules. The reaction worked on the Tetrahymena telomeric sequence C4A2 and also on the simple repeat CA. The reaction was orientation specific: it occurred only when the GT-rich strand ran 5' to 3' towards the end of the molecule. Telomere elongation occurred by non-template-directed DNA synthesis rather than any type of recombination with chromosomal telomeres, because C1-3A repeats could be added to unrelated DNA sequences between the CA-rich repeats and the terminus of the transforming DNA. The elongation reaction was very efficient, and we believe that it was responsible for maintaining an average telomere length despite incomplete replication by template-directed DNA polymerase. The resolution reaction processed a head-to-head inverted repeat of telomeric sequences into two new telomeres at a frequency of 10(-2) per cell division.
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Ibrahim, Abdulkhaleg, Christophe Papin, Kareem Mohideen-Abdul, Stéphanie Le Gras, Isabelle Stoll, Christian Bronner, Stefan Dimitrov, Bruno P. Klaholz et Ali Hamiche. « MeCP2 is a microsatellite binding protein that protects CA repeats from nucleosome invasion ». Science 372, no 6549 (24 juin 2021) : eabd5581. http://dx.doi.org/10.1126/science.abd5581.
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The Rett syndrome protein MeCP2 was described as a methyl-CpG-binding protein, but its exact function remains unknown. Here we show that mouse MeCP2 is a microsatellite binding protein that specifically recognizes hydroxymethylated CA repeats. Depletion of MeCP2 alters chromatin organization of CA repeats and lamina-associated domains and results in nucleosome accumulation on CA repeats and genome-wide transcriptional dysregulation. The structure of MeCP2 in complex with a hydroxymethylated CA repeat reveals a characteristic DNA shape, with considerably modified geometry at the 5-hydroxymethylcytosine, which is recognized specifically by Arg133, a key residue whose mutation causes Rett syndrome. Our work identifies MeCP2 as a microsatellite DNA binding protein that targets the 5hmC-modified CA-rich strand and maintains genome regions nucleosome-free, suggesting a role for MeCP2 dysfunction in Rett syndrome.
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Akkaya, M. S., A. A. Bhagwat et P. B. Cregan. « Length polymorphisms of simple sequence repeat DNA in soybean. » Genetics 132, no 4 (1 décembre 1992) : 1131–39. http://dx.doi.org/10.1093/genetics/132.4.1131.
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Abstract The objective of this work was to ascertain the presence and degree of simple sequence repeat (SSR) DNA length polymorphism in the soybean [Glycine max (L.) Merr.]. A search of GenBank revealed no (CA)n or (GT)n SSRs with n greater than 8 in soybean. In contrast, 5 (AT)n and 1 (ATT)n SSRs with n ranging from 14 to 27 were detected. Polymerase chain reaction (PCR) primers to regions flanking the six SSR loci were used in PCR amplification of DNA from 43 homozygous soybean genotypes. At three loci, amplification produced one PCR product per genotype and revealed 6, 7 and 8 product length variants (alleles) at the three loci, respectively. F1 hybrids between parents carrying different alleles produced two PCR products identical to the two parents. Codominant segregation of alleles among F2 progeny was demonstrated at each locus. A soybean DNA library was screened for the presence of (CA/GT)n SSRs. Sequencing of positive clones revealed that the longest such SSR was (CA)9. Thus, (CA)n SSRs with n of 15 or more are apparently much less common in soybean than in the human genome. In contrast to humans, (CA)n SSRs will probably not provide an abundant source of genetic markers in soybean. However, the apparent abundance of long (AT)n sequences should allow this SSR to serve as a source of highly polymorphic genetic markers in soybean.
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Kudryavtseva, E. V., V. V. Kovalev, I. I. Baranov, I. V. Kanivets, Yu K. Kievskaya et S. A. Korostelev. « Low Fetal Fraction of Cell-free DNA Identified by Non-invasive Prenatal DNA Testing : Possible Causes, Clinical Significance, and Tactics ». Doctor.Ru 19, no 8 (2020) : 49–54. http://dx.doi.org/10.31550/1727-2378-2020-19-8-49-54.
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Study Objective: To compare the rates of fetal chromosomal abnormalities (CA) detected during initial non-invasive prenatal DNA testing (NIPT) with the rates of CA found through repeat NIPT in patients with low fetal fraction or low quality of cell-free embryonic DNA. Study Design: This was a retrospective cohort study. Materials and Methods: Twenty-one thousand forty-two women who underwent NIPT in Russia between 2013 and 2018 were included in the study. The main group comprised 1,025 of the 1,044 patients with uninformative results (low fetal fraction result, making it impossible to assess the risk of CA), who consented to repeat NIPT. The control group was made up of 19,998 women who had informative results of initial NIPT. The exclusion group comprised women with low fetal fraction who declined repeat screening. The study method was targeted NIPT. Blood samples were taken from a vein and centrifuged to obtain plasma. Fetal cell-free DNA was analyzed by next-generation sequencing (NGS), a method patented by Natera for sequencing single nucleotide polymorphisms. Study Results: Initial NIPT was uninformative in 1,044 (5%) of the patients and repeat procedure yielded informative results in 821 (80.1%) out of 1,025 patients. Among the patients with informative results from the initial study, the rate of chromosomal aneuploidies was 2.4%. In the group of women with informative results from the repeat procedure, fetal CA were detected in 27 (3.3%) cases. In the subgroup of women with informative results only after a third NIPT, the prevalence of CA was 9.3% (seven out of 75 cases). The study showed that in women carrying fetuses with trisomy 18 or 13 or monosomy X, mean fetal fraction in the first trimester was significantly lower than normal. In the second trimester, significantly lower than normal fetal fraction was observed in women carrying fetuses with trisomy 18 or monosomy X. There was a statistically significant difference in fetal fraction levels between patients with body weight <50 kg and those with body weight 80-89 kg or above (р<0.05). Conclusion: The probability of detecting CA by repeat NIPT is significantly higher than in an initial procedure. If initial testing is not informative, it should be repeated. If the second procedure also fails to yield informative results, invasive prenatal diagnosis should be considered. Fetal fraction levels are lower in heavier women. Thus, other methods of prenatal diagnosis should be recommended for overweight and obese women. Keywords: non-invasive prenatal DNA testing, fetal fraction, prenatal diagnosis, Down syndrome.
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Peng, Xu, Kim Brügger, Biao Shen, Lanming Chen, Qunxin She et Roger A. Garrett. « Genus-Specific Protein Binding to the Large Clusters of DNA Repeats (Short Regularly Spaced Repeats) Present in Sulfolobus Genomes ». Journal of Bacteriology 185, no 8 (15 avril 2003) : 2410–17. http://dx.doi.org/10.1128/jb.185.8.2410-2417.2003.
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ABSTRACT Short regularly spaced repeats (SRSRs) occur in multiple large clusters in archaeal chromosomes and as smaller clusters in some archaeal conjugative plasmids and bacterial chromosomes. The sequence, size, and spacing of the repeats are generally constant within a cluster but vary between clusters. For the crenarchaeon Sulfolobus solfataricus P2, the repeats in the genome fall mainly into two closely related sequence families that are arranged in seven clusters containing a total of 441 repeats which constitute ca. 1% of the genome. The Sulfolobus conjugative plasmid pNOB8 contains a small cluster of six repeats that are identical in sequence to one of the repeat variants in the S. solfataricus chromosome. Repeats from the pNOB8 cluster were amplified and tested for protein binding with cell extracts from S. solfataricus. A 17.5-kDa SRSR-binding protein was purified from the cell extracts and sequenced. The protein is N terminally modified and corresponds to SSO454, an open reading frame of previously unassigned function. It binds specifically to DNA fragments carrying double and single repeat sequences, binding on one side of the repeat structure, and producing an opening of the opposite side of the DNA structure. It also recognizes both main families of repeat sequences in S. solfataricus. The recombinant protein, expressed in Escherichia coli, showed the same binding properties to the SRSR repeat as the native one. The SSO454 protein exhibits a tripartite internal repeat structure which yields a good sequence match with a helix-turn-helix DNA-binding motif. Although this putative motif is shared by other archaeal proteins, orthologs of SSO454 were only detected in species within the Sulfolobus genus and in the closely related Acidianus genus. We infer that the genus-specific protein induces an opening of the structure at the center of each DNA repeat and thereby produces a binding site for another protein, possibly a more conserved one, in a process that may be essential for higher-order stucturing of the SRSR clusters.
Thèses sur le sujet "CA repeat DNA"
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Guggenbuhl, Sylvain. « Étude structurale de complexes ADN de la protéine MeCP2 impliqués dans le syndrome de Rett ». Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAJ083.
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Le syndrome de Rett est une maladie génétique rare conduisant à un désordre neurologique grave, causée par des mutations de la protéine MeCP2. MeCP2 est une protéine de liaison à l’ADN dont le domaine MBD lie spécifiquement les cytosines hydroxyméthylées au sein de répétitions de dinucléotides CA. Dans cette thèse, je présente une étude structurale par cristallographie aux rayons-X et une caractérisation biophysique par ITC et NanoDSF des cinq mutations faux-sens les plus fréquentes du MBD de MeCP2 (T158M, R133C, R106, P152R et S134C) qui sont naturellement présentes chez les patients atteints du syndrome de Rett. Des structures comprenant les MBD P152R et S134C en complexe avec un ADN contenant une cytosine hydroxyméthylées au sein d’une répétition de dinucléotides CA ont pu être déterminées. Ces structures révèlent que les mutations causent une altération de l’interaction spécifique et critique de MeCP2, qui permet normalement la reconnaissance des cytosines hydroxyméthylées. De plus, la caractérisation biophysique des mutations du domaine MBD de MeCP2 révèle une baisse de l’affinité de liaison à l’égard des répétitions de dinucléotides CA hydroxyméthylées et une baisse de la stabilité du repliement du domaine pour certaines mutationsRett syndrome is a rare genetic disorder leading to severe neurological impairments. It is caused by mutations of the MeCP2 protein. MeCP2 is a DNA binding protein whose MBD domain specifically binds to hydroxymethylated cytosines in the context of CA dinucleotide repeats. This thesis presents a structural study by X-ray crystallography and a biophysical characterization by ITC and NanoDSF of the five most frequent mutations that are naturally affecting the MBD domain of MeCP2 in patients with Rett syndrome.The structures of the MBD P152R and S134C in complex with DNA containing a hydroxymethylated cytosine within a CA dinucleotide repeat have been determined. These structures reveal an alteration caused by the mutation of the specific and critical interaction of MeCP2 that usually enables the recognition of hydroxymethylated cytosines. In addition, the biophysical characterization of the mutations reveals a decrease of the binding affinity of the MBD toward hydroxymethylated CA dinucleotide repeats along with a decrease in the MBD folding stability for some mutations
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Alhammad, Ali M. « FACTORS INFLUENCING PHARMACISTS’ DECISION TO REPORT ADVERSE EVENTS RELATED TO DIETARY SUPPLEMENTS ». VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2849.
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Background: The increasing consumption of dietary supplements (DS) has drawn the attention of regulatory agencies, researchers and healthcare professionals. The US Food and Drug Administration (FDA) does not require premarketing assessment of DS considering them safe unless proven otherwise. However, the reporting rate of DS adverse events (DS-AE) is low. Objective: To describe pharmacists’ attitudes and knowledge of DS and DS information resources, and to determine the importance of selected attributes in pharmacists’ decisions to report a DS-AE. Methods: A convenience sample of practicing pharmacists in Virginia was surveyed using a web-based self-administered questionnaire. A conjoint analysis exercise was developed using several scenarios based on a set of five attributes: patient’s age, initiation of DS, last modification in drug therapy, evidence supporting the AE, and outcome of the AE. Participants were asked to indicate their decision to report the AE in each scenario to prescriber, drug manufacturer, DS manufacturer and FDA on a 6-point ordered scale. Participants’ attitude, knowledge of DS, demographic information, and DS information resources were also requested. Linear regression models were used to determine the relative importance of the profile attributes on a pharmacist’s decision to report the AE. The effects of other characteristics on the importance of the attributes were assessed. Results: Participants’ overall attitudes were relatively positive for the clinical use of DS but negative for safe of DS. Formal training on DS was associated with better knowledge of DS regulation. The average knowledge score of DS identification was relatively good but was low for DS regulation. Lexi-Comp® was the most widely used and available information resource and the Natural Medicines Comprehensive Database was the most useful once. The most important attribute that a pharmacist considered in the decision to report a DS-AE to DS manufacturer, drug manufacturer and FDA was the outcome of the AE followed by the evidence supporting the AE. Ranking of these two factors was the reversed in reporting to prescriber. Conclusions: Outcome and evidence of the AE are the most important factors participants considered when reporting. Other characteristics do not have an impact on the relative importance of the attributes.
Chapitres de livres sur le sujet "CA repeat DNA"
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Rassmann, Kornelia, Hans Zischler et Diethard Tautz. « DNA Multilocus Fingerprinting Using Simple Repeat Motif Oligonucleotides ». Dans Molecular Genetic Approaches in Conservation, 238–50. Oxford University PressNew York, NY, 1996. http://dx.doi.org/10.1093/oso/9780195095265.003.0015.
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Abstract The “invention” of multilocus minisatellite DNA fingerprinting in 1985 has provided conservation geneticists with a powerful new tool (Jeffreys, 1985b). Owing to the high average mutation rate of the genomic regions analysed in DNA fingerprinting, the multilocus band patterns or fingerprints normally reveal ample genetic variation (Jeffreys et al., 1988). Thus, multilocus fingerprinting can provide information on the genetic structure of individuals (heterozygosity) or populations (allelic diversity) where less sensitive methods such as enzyme electrophoresis might fail. Like minisatellite fingerprinting, simple sequence oligonucleotide fingerprinting detects multiple loci simultaneously in the eukaryotic genome. The technique is named after the specific hybridization probe employed: a synthetic single-stranded oligonucleotide, about 20 nucleotides in length. The sequence of this probe consists of a single, very short motif, for instance “CA” or “GTC,” which is repeated several times. Such a probe can hybridize with simple repetitive DNA loci in the eukaryotic genome. Since many repetitive DNA loci in the genome consist of the same repeat motif, simple sequence oligonucleotide fingerprinting produces a multilocus fingerprint pattern (for reviews on oligonucleotide fingerprinting see: Epplen, 1988; Epplen et al., 1991, 1993). The degree of genetic variation revealed in oligonucleotide fingerprints seems to be similar to that in minisatellite fingerprints. A study analysing several loci in the human genome that hybridize with the (CAC)5 oligonucleotide probe confirmed a very high average rate of germline mutations. The mutation rate of the resolvable DNA fragments containing such loci was estimated to be approximately 0.001 per locus per gamete (Niirnberg et al., 1989). The same study showed that the fingerprint patterns were somatically stable, thus providing support for the reliability of the method.
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Matzke, Marjori A., et Antonius J. M. Matzke. « Homology-dependent gene silencing in transgenic plants and related phenomena in other eukaryotes ». Dans Nuclear Organization, Chromatin Structure, and Gene Expression, 276–90. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780198549239.003.0016.
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Abstract Higher eukaryotic genomes contain substantial amounts of repetitive DNA. What limitations, if any, are placed on the quantity and distribution of repetitive sequences and do these parameters in tum influence gene expression? Some contend that non-genie repeated DNA sequences, which constitute ca. 30 per cent of mammalian genomes and 15—90 per cent of flowering plant genomes, are mostly non-functional ‘junk’ (John and Miklos 1988), while others suggest that they have essential structural and/or regulatory roles (Davidson and Britten 1979; Smyth 1991; see Chapter 13). In plants large disparities in DNA content arise primarily from differences in the repetitive fraction, as reflected in recent findings showing that even though DNA amounts can vary greatly in closely related species, gene composition and gene order remain relatively constant (synteny). This is particularly striking in the cereals (Moore et al. 1993). For example, the genetic linkage maps of rice and wheat are remarkably conserved, even though they differ 30-fold in DNA content (Kurata et al. 1994). These findings have prompted the remark that ‘rice is wheat without the repeats’ (G. Moore, quoted in Cherfas 1994). Noteworthy synteny has also been observed in related mammals (O’Brien and Graves 1991). Despite arguments to the contrary (John and Miklos 1988), it is difficult to abandon the notion that at least some of this repetitive DNA, particularly those sequences that are species specific, contributes to the differential regulation of a ‘generic’ protein-coding genome.
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Chicoș, Oana. « Bullyingul la limita dintre dreptul penal și psihologie ». Dans EVOLUȚII ȘI PERSPECTIVE ÎN DREPTUL CONTEMPORAN, 175–97. Editura Pro Universitaria, 2024. http://dx.doi.org/10.52744/978-606-26-1958-9.06.
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Bullying-ul este un concept relativ nou în vocabularul românesc, însă, dacă avem curiozitatea de a privi puțin în trecut, vom observa că acest concept a fost introdus în literatura de specialitate încă din anul 1978, de către psihologul norvegian Dan Olweus. La prima vedere, asociem acest comportament agresiv cu violența dintre elevi, însă, acesta nu se aplică exclusiv în rândul elevilor. Privim bullyingul ca un comportament agresiv și repetat, exercitat asupra unei persoane sau unui grup de persoane, însă este de subliniat faptul că acesta poate afecta profund nu numai elevii, tinerii ci și adulții și nu poate fi asociat doar cu un comportament antisocial, sau o problemă de comunicare socială. Este un comportament care duce indubitabil la o serie de acțiuni săvârșite cu intenție, ce au ca scop discriminarea și poate duce totodată și la excluderea socială. Persoanele care recurg la un asemenea comportament, respectiv persoanele care sunt și victime și agresori, raportează probleme emoționale, sociale și comportamentale. Victimele bullyingului pot dezvolta probleme de sănătate mintală, anxietate, depresie și în situații grave, acestea pot recurge chiar și la tentative de suicid sau chiar suicid. Pentru a înțelege mai bine acest fenomen, pe parcursul capitolului vom apela la experiența unor specialiști în domeniu și ne propunem să aducem cât mai aproape atât experiențele unor victime cât și ale unor agresori, a acestui flagel, exemplificate prin studii de caz. Important este faptul că nu trebuie confundat termenul de bullying cu cel de gulmă sau tachinare, întrucât sunt situații total diferite. Gluma sau tachinarea, au un caracter de divertisment, ce au ca scop o comunicare amuzantă, distractivă, pe când bullyingul este un comportament agresiv ce are de cele mai multe ori la bază un comportament antisocial.
Actes de conférences sur le sujet "CA repeat DNA"
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Ohyashiki, Junko H., Tomohiro Umezu, Michiyo Ohyashiki, Kazushige Ohtsuki, Chiaki Kobayashi et Kazuma Ohyashiki. « Abstract C19 : DNA demethylation induces upregulation of telomere repeat-containing RNA (TERRA) and downregulation of telomerase activity in human leukemia cells ». Dans Abstracts : Second AACR International Conference on Frontiers in Basic Cancer Research--Sep 14-18, 2011 ; San Francisco, CA. American Association for Cancer Research, 2011. http://dx.doi.org/10.1158/1538-7445.fbcr11-c19.
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Charlot, David Jean, Megha Bhalla, Raj Krishnan et Gene Tu. « Abstract 1522 : Direct quantitative PCR of LINE repeats to quantify CFC-DNA in serum ». Dans Proceedings : AACR Annual Meeting 2014 ; April 5-9, 2014 ; San Diego, CA. American Association for Cancer Research, 2014. http://dx.doi.org/10.1158/1538-7445.am2014-1522.
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Cantone, Laura, Valentina Bollati, Robert Wright, Augusto Litonjua, Letizia Tarantini, Helen Suh, David Sparrow, Pantel Vokonas, Andrea Baccarelli et Joel Schwartz. « Abstract 557 : Aging and DNA methylation in Alu and LINE-1 repeated elements ». Dans AACR Annual Meeting--Apr 12-16, 2008 ; San Diego, CA. American Association for Cancer Research, 2008. http://dx.doi.org/10.1158/1538-7445.am2008-557.
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Samuelsson, Johanna, Gabrijela Dumbovic, Sergio Alonso, Sonia Forcales et Manuel Perucho. « Abstract 1381 : Somatic DNA demethylation and epigenetic reprogramming of SST1 pericentromeric repeats associate with genomic damage in colorectal cancer ». Dans Proceedings : AACR Annual Meeting 2014 ; April 5-9, 2014 ; San Diego, CA. American Association for Cancer Research, 2014. http://dx.doi.org/10.1158/1538-7445.am2014-1381.
Texte intégralRapports d'organisations sur le sujet "CA repeat DNA"
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Fromm, Hillel, Paul Michael Hasegawa et Aaron Fait. Calcium-regulated Transcription Factors Mediating Carbon Metabolism in Response to Drought. United States Department of Agriculture, juin 2013. http://dx.doi.org/10.32747/2013.7699847.bard.
Texte intégralRésumé :
Original objectives: The long-term goal of the proposed research is to elucidate the transcription factors, genes and metabolic networks involved in carbon metabolism and partitioning in response to water deficit. The proposed research focuses on the GTLcalcium/calmodulinbindingTFs and the gene and metabolic networks modulated by these TFs in Arabidopsis thaliana. The specific objectives are as follows. Objective-1 (USA): Physiological analyses of GTL1 loss- and gain-of-function plants under water sufficient and drought stress conditions Objective 2 (USA / Israel-TAU): Characterizion of GTL target genes and bioinformatic analysis of data to eulcidate gene-network topology. Objective-3 (Israel-TAU): Regulation of GTLmediated transcription by Ca²⁺/calmodulin: mechanism and biological significance. Objective-4 (Israel-BGU): Metabolic networks and carbon partitioning in response to drought. Additional direction: In the course of the project we added another direction, which was reported in the 2nd annual report, to elucidate genes controlling drought avoidance. The TAU team has isolated a few unhydrotropic (hyd) mutants and are in the process of mapping these mutations (of hyd13 and hyd15; see last year's report for a description of these mutants under salt stress) in the Arabidopsis genome by map-based cloning and deep sequencing. For this purpose, each hyd mutant was crossed with a wild type plant of the Landsberg ecotype, and at the F2 stage, 500-700 seedlings showing the unhydrotropic phenotype were collected separately and pooled DNA samples were subkected to the Illumina deep sequencing technology. Bioinformatics were used to identify the exact genomic positions of the mutations (based on a comparison of the genomic sequences of the two Arabidopsis thaliana ecotypes (Columbia and Landsberg). Background: To feed the 9 billion people or more, expected to live on Earth by the mid 21st century, the production of high-quality food must increase substantially. Based on a 2009 Declaration of the World Summit on Food Security, a target of 70% more global food production by the year 2050 was marked, an unprecedented food-production growth rate. Importantly, due to the larger areas of low-yielding land globally, low-yielding environments offer the greatest opportunity for substantial increases in global food production. Nowadays, 70% of the global available water is used by agriculture, and 40% of the world food is produced from irrigated soils. Therefore, much needs to be done towards improving the efficiency of water use by plants, accompanied by increased crop yield production under water-limiting conditions. Major conclusions, solutions and achievements: We established that AtGTL1 (Arabidopsis thaliana GT-2 LIKE1) is a focal determinant in water deficit (drought) signaling and tolerance, and water use efficiency (WUE). The GTL1 transcription factor is an upstream regulator of stomatal development as a transrepressor of AtSDD1, which encodes a subtilisin protease that activates a MAP kinase pathway that negatively regulates stomatal lineage and density. GTL1 binds to the core GT3 cis-element in the SDD1 promoter and transrepresses its expression under water-sufficient conditions. GTL1 loss-of-function mutants have reduced stomatal number and transpiration, and enhanced drought tolerance and WUE. In this case, higher WUE under water sufficient conditions occurs without reduction in absolute biomass accumulation or carbon assimilation, indicating that gtl1-mediated effects on stomatal conductance and transpiration do not substantially affect CO₂ uptake. These results are proof-of-concept that fine-tuned regulation of stomatal density can result in drought tolerance and higher WUE with maintenance of yield stability. Implications: Accomplishments during the IS-4243-09R project provide unique tools for continued discovery research to enhance plant drought tolerance and WUE.