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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
Blood pressure patterns in normal pregnancy and in pregnancy-induced hypertension, preeclampsia, and chronic hypertension
No full textObjective: To compare the 24-hour blood pressure (BP) pattern in physiologic pregnancy, pregnancy-induced hypertension, preeclampsia, and chronic hypertension. Methods: We investigated four groups of women with singleton pregnancy: 73 controls, 48 patients with pregnancy-induced hypertension, 38 with preeclampsia, and 53 with mild to moderate chronic hypertension. The 24-hour BP monitoring was performed longitudinally in controls and in patients with chronic hypertension, and at the time of diagnosis in those with pregnancy-induced hypertension or preeclampsia. Results: Nineteen thousand eight hundred seventy-two BP measurements were analyzed. In controls, the mean values of BP indices were lower than those first reported in non-pregnant women, and the acrophase was always localized in the first part of the afternoon. In pregnancy-induced hypertension and especially in preeclampsia, besides the obvious quantitative increase in BP, circadian BP oscillations were less pronounced than in controls, and the severity of hypertension seemed to favor the loss of diurnal rhythm. Conversely, in chronic hypertension, circadian oscillations were the same as in controls. Conclusion: Standardized 24-hour BP monitoring during pregnancy allows quantitative and qualitative evaluations of the hypertensive status. However, if such a technique is used routinely in every clinical setting, we should establish specific thresholds of normality for pregnancy
Increased L-citrulline/L-arginine plasma ratio in severe preeclampsia.
No full textTo evaluate nitric oxide (NO) production in patients with pregnancy-induced hypertension or preeclampsia and in controls.Four groups of pregnant women were included: 17 patients with pregnancy-induced hypertension, ten with mild or moderate preeclampsia, 17 with severe preeclampsia, and 44 normotensive women matched for weeks of gestation at blood sampling with the cases. Plasma levels of L-citrulline and L-arginine were measured by using high-performance liquid chromatography.The mean plasma levels of L-citrulline and the ratio of L-citrulline to L-arginine, which reflects NO production, were higher in women with severe preeclampsia than in controls, patients with pregnancy-induced hypertension, and patients with mild or moderate preeclampsia.Nitric oxide production is enhanced in severe preeclampsia, possibly as a compensatory phenomenon for the increased synthesis and release of vasoconstrictors and platelet-aggregating agents
Thrombophilic mutations are a main risk factor for placental abruption.
Full text linkThe aim of the present study was to evaluate inherited thrombophilic factor V Leiden and factor II A20210 mutations in women presenting with abruption of a normally implanted placenta.In a multi-center, case-control study, 50 consecutive women requiring immediate delivery because of abruption of the placenta were enrolled. Inclusion criteria were: abruptio placentae requiring immediate delivery, normally implanted placenta, Caucasian ethnic background, parity 5 cm, illicit drug abuse, premature rupture of membranes, multiple pregnancy. One hundred Caucasian women with uneventful pregnancies carried to term, matched for parity and age, served as controls.Heterozygotes were found to be significantly more prevalent among women with abruptio placentae than among controls. The carriership of the FV Leiden mutation confers a OR of 9.12 (95\% C.I.: 2.18-31.7; p=0.0005). Women carrying F II A20210 mutation have a OR of 12.25 (95\% C.I.: 2.36-29.6; p=0.0004). No homozygotes or double heterozygotes were found. Twenty-three patients (46\%) also met the criteria for a diagnosis of pre-eclampsia (PE). In such cases the prevalence of mutations (factor V: 6 cases, 26.1\%; factor II: 5 cases, 21.7\%) was similar to that in women without pre-eclampsia (factor V: 5 cases, 18.7\%; factor II: 5 cases, 18.5\%).The presence of either of the above reported thrombophilic mutations represents a relevant risk factor for the occurrence of placental abruption in Caucasians. This risk is independent of the development of pre-eclampsia. Patients who have had dramatic abruption of a normally implanted placenta should undergo evaluation for the presence of genetic mutations of coagulation factors V and II
Low-dose aspirin in prevention and treatment of intrauterine growth retardation and pregnancy-induced hypertension
No full textMeta-analysis of data from several controlled trials has shown that low-dose aspirin reduces the risk of pregnancy-induced hypertension (PIH) and intrauterine growth retardation (IUGR) in women at high risk of these disorders. We have assessed the efficacy of low-dose aspirin in women judged to be at moderate risk. Women were included on prophylactic criteria--age under 18 or over 40 years, mild or moderate chronic hypertension (diastolic pressure between 90 and 110 mm Hg), nephropathy with normal renal function and blood pressure, history of PIH or IUGR, and twin pregnancy--or therapeutic criteria--PIH or early signs of IUGR in current pregnancy. Eligible women were randomly assigned treatment with 50 mg aspirin daily until delivery (583) or no treatment (523); 18 and 46 women, respectively, were lost to follow-up. The groups were well matched for baseline characteristics. We found no differences between the no-treatment and aspirin groups in numbers of spontaneous (5 vs 2) or therapeutic (1 vs 2) abortions, stillbirths (14 vs 13), perinatal mortality (35.7 vs 28.6 per 1000 births), mean birthweight (2858 [SD 729] vs 2874 [795] g), proportion of infants with birthweights below the 10th centile (95 [18.3%] vs 117 [19.0%]), or births before 37 weeks' gestation (184 [35.6%] vs 209 [33.9%]). Nor did the groups differ in the frequency of PIH with or without proteinuria (51 [15.2%] vs 81 [19.3%]). There was no difference in mean birthweight between the treatment groups in separate analyses according to criteria for trial entry and week of gestation at randomisation. Our study gives little support to the notion that low-dose aspirin is beneficial in women at moderate risk of PIH or IUGR
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
Risk factors for pregnancy-induced hypertension in women at high risk for the condition. Italian Study of Aspirin in Pregnancy Group
No full textTo analyze determinants of the risk of pregnancy-induced hypertension (PIH) with or without proteinuria, we compared characteristics of women enrolled in the Italian Study of Aspirin in Pregnancy who developed PIH and those who did not. A total of 756 women were included in the present analysis; of these, 132 women (17%) developed PIH during the trial. The risk of developing PIH tended to increase with maternal age: in comparison with women age 20-25 years, the odds ratio (OR) estimates of risk ratio were 3.5 [95% confidence interval (CI) = 1.6-7.1] in women age 26-30 years and 4.2 (95% CI = 1.9-8.8) in those age > 30 years. There was little relation between development of PIH and education. PIH risk increased according to nonpregnant body mass index; in comparison with women with Quetelet's index (kg per m2) 25-30 and > 30. Parous women were at decreased risk of PIH: in comparison with nulliparas, the ORs were 0.7 (95% CI = 0.4-1.0) and 0.5 (95% CI = 0.3-0.9), respectively, in women reporting 1 or > or = 2 births. There was no important relation between previous spontaneous or induced abortion and PIH risk
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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