1,721,046 research outputs found
Sperimentazioni di rilievo di concentrazioni di CO in Pisa mediante metodo topografico cinematico GPS
No full textSNP variation in the bitter taste TAS2R38 gene evaluated in student populations of several italian universities and isolates
No full textPeople vary widely in their sensitivities to bitter compounds, but the all intercorrelation of these sensitivities is unknown. The study of genetic influences on bitter taste perception originated from the discovery in the 1930s that some individuals had taste to phenylthiocarbamide(PTC), whereas others found it extremely bitter. Subsequently, many studies were carried out on PTC and the structurally related compound propylthiouracil (PROP) to assess this viability and to determine the root causes. Initial family studies strongly suggested that PTC no tasting was due to a recessive allele in a single gene and heritability was estimated at 0,5. 55-85% of variation in PTC detection. The PTC gene, TAS2R38 on chromosome 7, consists of a small, single coding exon 1002 bp. The non-tester allele differs from the tester one for three single nucleotide polymorphisms (SNPs) at position 49, 262 and 296 in the gene, determining two predominant haplotypes. The phenotypic assay to differentiate taster from non-taster is relatively easy and quick, as well as the genotyping of the known polymorphisms. Therefore, this phenotypic-genotypic assay results to be particularly suitable for molecular and population genetic studies on large populations and for teaching genetics at university and high school level by allowing students to assess the genotype-phenotype relationship on themselves. By providing students with paper samples soaked in different solutions of PTC and PROP it was been possible to assess the individual threshold of bitterness sensitivity. DNA was extracted from saliva by means of Qiagen Kit mini, and following PCR amplification, polymorphisms were evaluated by gel electrophoresis. We started to develop this assay involving hundreds of students of several Italian universities such as Caltanissetta, Palermo, Catania, Cosenza in the South of Italy, Pisa and Parma in the Centrum of Italy with the aim to describe the Italian population for this polymorphism. By considering the large number of samples, we expect to be able to assess the frequency of additional rare polymorphisms, possibly further characterizing defined populations. A detailed questionnaire concerning life style and diet was also administered to students for possible association studies with the genetic polymorphism. Moreover, investigations on isolated populations such as these leaving in mountains of Garfagnana (Lucca) was undertaken. The distribution frequency of TAS2R38 polymorphisms in different sub sets of Italian population and isolates, the possible relationship with food preferences and other life styles, such as alcohol drinking and smoking will be reported and discussed. Functional expression studies demonstrate that five different haplotypes from the hTAS2R38 gene, code for operatively distinct receptors. The responses of the three haplotypes we also tested in vivo correlate strongly with individuals' psychophysical bitter sensitivities to a family of compounds. These data provide a direct molecular link between heritable variability in bitter taste perception to functional that contain the N-C= moiety. The molecular mechanisms of perceived bitterness variability have therapeutic implications, such as helping patients to consume beneficial bitter-tasting compounds, for example, pharmaceuticals and selected phytochemicals (Bufe 2005). Our goal is to investigate correlations as a function of individual sensitivities to several bitter compounds representative of different chemical classes and, from these correlations, infer the number and variety of potential bitterness transduction system
Chromosomal fragile sites FRA3B and FRA16D show correlated expression and association with failure of apoptosis in lymphocytes from patients with thyroid cancer.
No full textIt has been suggested that common fragile sites (cFSs) are related to cancer development. This appears to be the case for FRA3B and FRA16D, localized in two tumor-suppressor genes (FHIT and WWOX, respectively) that are altered by deletions or
loss of heterozygosity (LOH) in many cancers. The features responsible for fragility have not yet been identified. Furthermore,
it is still unclear whether instability at these regions causes chance deletions and loss of function of the associated genes, or
whether the gene function itself is related to the appearance of fragility. In this study, we analyzed cFS expression in lymphocytes
from 20 healthy or thyroid cancer–affected subjects exposed to radiation after the Chernobyl accident. The same cells
were examined for apoptosis, a principal function of both the FHIT and WWOX genes. Exceptionally elevated chromosome fragility
was observed, particularly in cancer patients, affecting FRA3B, FRA16D, and a cluster of less highly expressed cFSs; levels
of chromosome fragility were found to be correlated among these cFSs. Interestingly, most expressed cFSs were sites of LOH
reported for thyroid tumors; moreover, cells with the highest fragility also had a reduced ability to undergo apoptosis. These
findings reveal previously unknown genetic interactions affecting fragile loci, suggestive of a shared function inside mitotic cells.
Attenuation of checkpoint control and apoptosis resistance seem to be the cell phenotypes associated with unusual chromosome
fragility. We propose that breakage at specific cFS could derive from early epigenetic events at loci involved in radiation carcinogenesis
Common fragile sites on human chromosomes represent transcriptionally active regions: evidence from camptothecin
No full textCellular processes involved in the expression of fragile sites (FS) have been investigated by studying the possible modulation of their induction by camptothecin, a specific topoisomerase I inhibitor. Expression of FS was induced by aphidicolin and then camptothecin was administered to cultures during G2 phase. Under these conditions, a very high number of chromosome aberrations were obtained: R-bands carrying FS were specifically involved in breakage and, in particular, the common FS (cFS) bands already expressed in aphidicolin-treated cultures were the most affected. These data show that the expressed FS are preferential targets of camptothecin, that is, regions where topoisomerase I-cleavable complexes are formed. This allows us to hypothesize that cFS could represent the cytogenetic expression of transcriptionally active regions. These treatments were able to induce, besides the known FS, four new FS, namely 1p34, 6p21, 6q25, and 15q15
Endogenous sex hormones affect the mutagen-induced chromosome damage by altering a caffeine-sensitive checkpoint
No full textIn the present study we analysed the effect of endogenous sex hormones on the SCE frequencies induced in vitro by mitomycin C (MMC), a bifunctional alkylating agent producing high chromosome damage and mitotic arrest. The analysis has been performed on lymphocytes obtained at three different phases of menstrual cycle, from women with regular cycle and hormones dosage. At all phases we further analysed the effect of a post-treatment with caffeine, an agent that it is known to overrride the DNA damage checkpoints. After MMC, the cultures obtained at ovulation and luteal phases have SCE frequencies statistically higher than the cultures obtained at the progestogenic phase, showing increases of 15 and 25%, respectively. After caffeine, the MMC treated cultures which were set up at the progestogenic phase show a high potentiation of SCE frequencies (28%) whereas the treated cultures set up at ovulatory and luteal phases show little or no potentiation. These findings demonstrate that the endogenous hormones greatly modulate the SCE frequencies induced by the mutagen; they also indicate that hormones action competes with the caffeine effect. Caffeine acts by abrogating the mitotic arrest produced by DNA damage and induced cells with a higher chromosome damage into a premature mitosis. Our findings suggest that endogenous hormones could overcome the checkpoint controls activated in cells after mutagenic exposure. This action may be an epigenetic mechanism relevant in hormone carcinogenesis. © 2004 Elsevier B.V. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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