1,720,973 research outputs found
A simplified method to determine binding parameters in a two-site case using linear regression.
No full textSpecific concordance index defines the physiological lag between LH and progesterone in women during the midluteal phase of the menstrual cycle
No full textUsing a recently developed statistically based method for assessment of the degree of concordance, we evaluated the degree of specific concordance (SC) between luteinizing hormone (LH) and progesterone secretory patterns. Eight healthy women volunteered for this study, undergoing a 12-h pulsatility study, sampling every 10 min. LH and progesterone pulse frequencies were estimated with the program DETECT (9.75 +/- 1 and 11.5 +/- 0.9 pulses/12 h, respectively; mean +/- SEM). The temporal relationship between LH and progesterone secretions was evaluated with cross-correlation analysis and with the computation of the SC index. Cross-correlation showed concordance between LH and progesterone (p less than 0.05) at a range of lag between 0 and 40 min, while the SC index indicated that LH and progesterone pulses were significantly (p less than 0.05) and maximally correlated at 10-min lag. In conclusion, our data demonstrated that the specific concordance confirms the statistically significant concordance of LH and progesterone secretory events in women during the midluteal phase. In addition, the use of this new, objective, statistically based approach permits, compared to traditional cross-correlation analysis, a more precise definition of the physiological time lag for temporal coupling of secretory events between the two hormones
Un aggiornamento sull’impatto della ricerca scientifica e tecnologica italiana in ambito internazionale (1981-2004). Analisi preliminare.
No full textSpecific concordance index defines the physiological lag between LH and progesterone in women during the midluteal phase of the menstrual cycle.
No full textUsing a recently developed statistically based method for assessment of the degree of concordance, we evaluated the degree of specific concordance (SC) between luteinizing hormone (LH) and progesterone secretory patterns. Eight healthy women volunteered for this study, undergoing a 12-h pulsatility study, sampling every 10 min. LH and progesterone pulse frequencies were estimated with the program DETECT (9.75 +/- 1 and 11.5 +/- 0.9 pulses/12 h, respectively; mean +/- SEM). The temporal relationship between LH and progesterone secretions was evaluated with cross-correlation analysis and with the computation of the SC index. Cross-correlation showed concordance between LH and progesterone (p less than 0.05) at a range of lag between 0 and 40 min, while the SC index indicated that LH and progesterone pulses were significantly (p less than 0.05) and maximally correlated at 10-min lag. In conclusion, our data demonstrated that the specific concordance confirms the statistically significant concordance of LH and progesterone secretory events in women during the midluteal phase. In addition, the use of this new, objective, statistically based approach permits, compared to traditional cross-correlation analysis, a more precise definition of the physiological time lag for temporal coupling of secretory events between the two hormones
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)
Why, when and how to adjust for multiplicity in clinical trials : a perspective on regulatory activities
Full text linkThe need for multiplicity adjustments in clinical trials is a very controversial issue. The aim of this paper is to provide general recommendations that can help determine whether multiplicity adjustment is necessary.
A brief overview of the most commonly encountered multiplicity adjustment methods and of the multiplicity issues that often arise in clinical trial settings (multiple endpoints, subgroups, multiple doses or treatments and interim monitoring) is given. To provide an insight into the Italian context, protocols which have been evaluated by the Ethical Committee of the Policlinico of Padova from January 2009 to May 2010 are reviewed and discussed.
The literature suggests that there is no one single method for multiplicity adjustment that is preferred in all instances. Regardless of which approach is used, however, the selected procedure must be specified in the clinical trial protocol and statistical plan before undertaking any analyses of the data.
Multiplicity adjustments are related to the need of the clinical research to fully exploit the information from clinical trials and their usage should be motivated by the effective benefits of exploiting such information at the maximum extent
Differentiation induces pituitary adenylate cyclase-activating polypeptide receptor expression in PC-12 cells
No full text
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
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