1,720,957 research outputs found
Pharmacogenetics in ovarian stimulation. Current concepts and future options.
No full textTailoring ovarian stimulation to the individual patient can be challenging because the ovarian response varies substantially between patients. Pharmacogenetics has emerged as a new area of research to improve the balance between desired and undesired actions of drugs, based upon the genetic predisposition of the individual patient. Clinical studies have demonstrated that the p.N680S polymorphism of the FSH-receptor gene determines the ovarian response to FSH stimulation in patients undergoing IVF. In homozygous Ser680/Ser680 type women, the FSH receptor appears to be more resistant to FSH action even in normal menstrual cycles. Therefore, genotyping of patients scheduled for ovarian stimulation could be an attractive tool to individualize FSH dosing according to genetic differences in ovarian sensitivity. More clinical studies are warranted to investigate the usefulness of genotyping for the p.N680S polymorphism as a routine diagnostic test before ovarian stimulation
A common single nucleotide polymorphism in exon 10 of the human follicle-stimulating hormone receptor is a major determinant of length and hormonal dynamics of the menstrual cycle.
No full textCONTEXT: FSH is essential for follicular maturation. Data from ovarian hyperstimulation cycles suggest that FSH action is attenuated by a frequent single nucleotide polymorphism of the FSH receptor gene exchanging Asn for Ser at codon 680. OBJECTIVE: We hypothesized that the FSH receptor genotype influences menstrual cycle dynamics. DESIGN: Menstrual cycle was monitored from the midluteal phase through ovulation until the consecutive menstruation. SETTING: The study was conducted at the University research center. SUBJECTS: Women homozygous for the Asn680 (n = 12) and Ser680 (n = 9) variants with normal menstrual cycles volunteered for the study. INTERVENTIONS: There were no interventions. MAIN OUTCOME MEASUREMENTS: Follicular growth, serum LH, FSH, estradiol, progesterone, inhibin A, inhibin B and antimullerian hormone were measured. RESULTS: During the luteo-follicular transition, serum levels of estradiol, progesterone, and inhibin A were significantly lower, and FSH started to rise earlier in the Ser680/Ser680 group. FSH levels were steadily and significantly higher, and the mean area under the FSH curve was 31% greater in this group (P < 0.002). No differences were observed in estradiol, inhibin B, and growth velocities of dominant follicles. The time from luteolysis to ovulation was significantly longer in women with the Ser680/Ser680 (13.6 +/- 1.01 d) compared with Asn680/Asn680 (11.3 +/- 0.61 d, P < 0.05) genotype with a significant difference in total menstrual cycle length (29.3 vs. 27.0 d, respectively; P < 0.05). CONCLUSIONS: The FSH receptor Ser680/Ser680 genotype is associated with higher ovarian threshold to FSH, decreased negative feedback of luteal secretion to the pituitary during the intercycle transition, and longer menstrual cycles
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
Significance of a common single nucleotide polymorphism in exon of the follicle-stimulating hormone receptor gene for ovarian response to FSH: a pharmacogenetic approach to control ovarian hyperstimulation.
No full textThe p.N680S sequence variation of the follicle-stimulating hormone (FSH) receptor gene was previously shown to influence the ovarian response to FSH in normo-ovulatory women undergoing controlled ovarian hyperstimulation. In this prospective, randomized, controlled study, we tested whether the same daily dose of FSH results in lower levels of oestradiol in women homozygous for the p.N680S sequence variation, and whether the difference can be overcome by higher FSH doses. Women undergoing controlled ovarian hyperstimulation for in vitro fertilization or intracytoplasmic sperm injection and homozygous for the wild-type or for the p.N680S FSH receptor were randomly assigned to group I (Ser/Ser, n=24), receiving an FSH dose of 150 U/day, or group II (Ser/Ser, n=25), receiving an FSH dose of 225 U/day. In group III (Asn/Asn, n=44), the FSH dose was 150 U/day. Age and basal FSH levels were not different between groups. At ovulation induction, total FSH doses were comparable in group I (1631+/-96 U) and group III (1640+/-57 U) but significantly higher in group II (2421+/-112 U) (P<0.001). Peak oestradiol levels on the day of human chorionic gonadotrophin (hCG) administration were significantly lower in group I (5680+/-675 pmol/l) compared to group III (8679+/-804 pmol/l) (P=0.028). Increasing the FSH dose from 150 to 225 U/day overcame the lower oestradiol response in women with Ser/Ser (group II, 7804+/-983 pmol/l). In women undergoing controlled ovarian hyperstimulation, the p.N680S sequence variation results in lower oestradiol levels following FSH stimulation. This lower FSH receptor sensitivity can be overcome by higher FSH doses
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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