1,720,998 research outputs found
Use of receiver operating characteristic curve to evaluate sensitivity, specificity, and accuracy of methods for detection of peaks in hormone time series.
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OBJECTIVE ASSESSMENT OF CONCORDANCE OF SECRETORY EVENTS IN 2 ENDOCRINE TIME-SERIES
No full textA new objective method is presented for investigating the presence of a temporal relationship between episodic release of two hormones. The two time series of hormone concentrations are first analysed by an objective method for peak detection. Both data series are then transformed into quantized or discretized series by recording the occurrence of a hormone pulse as an event, characterized by the onset, the maximum, or another unique feature. The two quantized series are then matched, and the number of concordant events and discordant events are counted. Each point in series A is compared with a time-window of a selected number of points in series B, to accommodate small degree of mismatch between events in the two series. An index of concordance is computed, compensating for any spurious random coincidence: the Specific Concordance, to evaluate the frequency of concordant events in excess of those expected on the basis of chance alone. This calculation is systematically repeated, interposing a range of time-lags between the two series. A graph of Specific Concordance versus time-lag indicates the time-lag corresponding to a maximal concordance. Simulations of random series of events are performed, and their degree of concordance is evaluated in a similar fashion, thus generating frequency distributions of Specific Concordance values under the null hypothesis of no temporal relationship. This permits the selection of criteria for statistical significance at any desired p-level, for one or many lag times, and for one or multiple subjects. Various degrees of concordance can also be simulated to evaluate the performance (sensitivity, statistical power) of this approach. These methods have been implemented as a collection of short microcomputer programmes, and applied to the study of the temporal relationship between beta-endorphin and cortisol in normal subjects sampled every 10 min for 24 h. This analysis demonstrated concordance between events in the two series, with synchronous occurrence of beta-endorphin and cortisol release events significantly more frequently than expected on the basis of random association (p < 0.01)
Estimation of instantaneous secretory rate of luteinizing hormone in women during the menstrual cycle and in men
No full textIn both men and women the pulsatile secretory pattern of LH has been extensively characterized. In the present study we used the algorithm for computation of instantaneous secretory rate (ISR) incorporated into the DETECT program to evaluate the secretory activity of gonadotrophs in vivo. We studied the pulsatile release of LH in four healthy women during four phases of the same menstrual cycle (early and late follicular and luteal phases) and in five healthy men. Computation of ISR permitted us to estimate the frequency and the duration of the secretory events from the gonadotrophs. Samples were collected every 10 min for 6 h. The apparent LH pulsatile frequency during the menstrual cycle varied from 5.0 +/- 0.8 (mean +/- SD) during the early follicular phase (EFP) to 5.3 +/- 1.2 peaks/6h during the late follicular phase (LFP), to 3.3 +/- 1.0 during early luteal phase (ELP) and to 5.3 +/- 0.4 peaks/6h during the late luteal phase (LLP). The mean pulse duration also changed throughout the phases of the cycle (EFP 47.4 +/- 13.2 min; LFP 55.4 +/- 21.6 min; ELP 100 +/- 50.4 min; LLP 48.1 +/- 11 min). In healthy men the LH pulse frequency was 3.8 +/- 1.6 peaks/6h and the duration was 71.5 +/- 35.7 min. When time series were analysed for ISR determination no significant changes were observed between the LH pulse frequency detected on ISR and that observed on plasma concentrations. Conversely, a significant reduction of the duration of the pulses was found when using ISR instead of plasma concentration.(ABSTRACT TRUNCATED AT 250 WORDS
Estimation of instantaneous secretory rate of luteinizing hormone in women during the menstrual cycle and in men.
No full textIn both men and women the pulsatile secretory pattern of LH has been extensively characterized. In the present study we used the algorithm for computation of instantaneous secretory rate (ISR) incorporated into the DETECT program to evaluate the secretory activity of gonadotrophs in vivo. We studied the pulsatile release of LH in four healthy women during four phases of the same menstrual cycle (early and late follicular and luteal phases) and in five healthy men. Computation of ISR permitted us to estimate the frequency and the duration of the secretory events from the gonadotrophs. Samples were collected every 10 min for 6 h. The apparent LH pulsatile frequency during the menstrual cycle varied from 5.0 +/- 0.8 (mean +/- SD) during the early follicular phase (EFP) to 5.3 +/- 1.2 peaks/6h during the late follicular phase (LFP), to 3.3 +/- 1.0 during early luteal phase (ELP) and to 5.3 +/- 0.4 peaks/6h during the late luteal phase (LLP). The mean pulse duration also changed throughout the phases of the cycle (EFP 47.4 +/- 13.2 min; LFP 55.4 +/- 21.6 min; ELP 100 +/- 50.4 min; LLP 48.1 +/- 11 min). In healthy men the LH pulse frequency was 3.8 +/- 1.6 peaks/6h and the duration was 71.5 +/- 35.7 min. When time series were analysed for ISR determination no significant changes were observed between the LH pulse frequency detected on ISR and that observed on plasma concentrations. Conversely, a significant reduction of the duration of the pulses was found when using ISR instead of plasma concentration
DERANGEMENT OF LH EPISODIC SECRETION IN CLUSTER HEADACHE SUFFERERS
No full textIn patients with cluster headache (CH) testosterone plasma levels have been consinstently reported to be lower than in normal males. Thus, we studied LH pulsatile secretory pattern in a group of 29 males suffering from CH. Ten of them were studied longitudinally, while 19 were studied cross-sectionally only during active (n=9) or attack free (n=10) phases. Nine healthy, age-matched males were studied as reference group. All subjects underwent a pulsatility study of 6 hours, sampling every 15 minutes. CH patients resulted to have a lower LH pulsatile release both during active (3.6+/-0.9 peaks/6h, p<0.0001) and attack free (4.1+/-0.9 peaks/6h, p<0.004) phases than normal males (5.2+/-0.6 peaks/6h). When longitudinally studied, CH patients (n=10) showed lower LH secretory episodes during the active than during the attack free phase (3.3+/-0.9 and 4.1+/-0.7 peaks/6h, p<0.05). Testosterone plasma levels did not differ between active and free phases (4.3+/-1 and 4.7+/-0.8 ng/ml, respectively), while, in patients they were significantly lower than in controls (6.8+/-0.9 ng/ml, p<0.01)). These data demonstrate an impaired function of the hypothalamo-pituitary axis possibly due to an overactivity of the opioid neuromodulation
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
Vasopressin receptors in human seminal vesicles: identification, pharmacologic characterization, and comparison with the vasopressin receptors present in the human kidney.
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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
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