Search results for "Regression analysis"
showing 10 items of 807 documents
Inclusion of Instantaneous Influences in the Spectral Decomposition of Causality: Application to the Control Mechanisms of Heart Rate Variability
2021
Heart rate variability is the result of several physiological regulation mechanisms, including cardiovascular and cardiorespiratory interactions. Since instantaneous influences occurring within the same cardiac beat are commonplace in this regulation, their inclusion is mandatory to get a realistic model of physiological causal interactions. Here we exploit a recently proposed framework for the spectral decomposition of causal influences between autoregressive processes [2] and generalize it by introducing instantaneous couplings in the vector autoregressive model (VAR). We show the effectiveness of the proposed approach on a toy model, and on real data consisting of heart period (RR), syst…
Uridine uptake inhibition as a cytotoxicity test for a human hepatoma cell line (HepG2 cells): comparison with the neutral red assay
2001
International audience; This study describes a sensitive microassay for measuring cytotoxicity based on the degree of inhibition of RNA synthesis in HepG2 cells. RNA synthesis is measured by the kinetic uptake of radiolabeled uridine. A large number of compounds were tested in a wide range of concentrations. The concentration required to induce 50% inhibition of HepG2 uridine uptake rates (IC50) was determined for each compound and used to rank its potency. These IC50s were compared with IC50s measured with the neutral red assay. 2-acetylaminofluorene, benzo[a]pyrene and methylnitrosourea were not cytotoxic in the neutral red assay. Uridine uptake was always inhibited at lower concentrations…
Food plant diversity as broad-scale determinant of avian frugivore richness.
2007
The causes of variation in animal species richness at large spatial scales are intensively debated. Here, we examine whether the diversity of food plants, contemporary climate and energy, or habitat heterogeneity determine species richness patterns of avian frugivores across sub-Saharan Africa. Path models indicate that species richness of Ficus (their fruits being one of the major food resources for frugivores in the tropics) has the strongest direct effect on richness of avian frugivores, whereas the influences of variables related to water–energy and habitat heterogeneity are mainly indirect. The importance of Ficus richness for richness of avian frugivores diminishes with decreasing sp…
The relationship between situational and contextual self-determined motivation and physical activity intensity as measured by heart rates during nint…
2008
The aim of the study was to investigate the relationships between situational and contextual self-determined motivation and physical activity intensity as measured by heart rates during a ninth-grade students' physical education (PE) class. The participants of the study were 139 Finnish ninth-grade students (15-year-olds). The data were collected during one 60-minute PE class held by the class PE teacher. Results revealed that more self-determined situational motivation negatively predicted the lowest heart rate category (<120 beats/min.) as well as the next lowest heart rate category (120—40 beats/min.). Neither variation in type of situational or contextual motivations explained heart…
Effects of p63 expression on survival in oral squamous cell carcinoma
2007
BACKGROUND: P63 is the protein codified by p63 gene, a p53 gene homolog, known for its pivotal role in cell cycle regulation, and involved in the tumor differentiation. Aims of the present study were to assess the frequency and pattern of p63 protein expression in oral squamous cell carcinoma (OSCC) in relation to the main tumour characteristics and to verify whether p63 can be considered a marker of prognosis in patients with OSCC. MATERIAL AND METHODS: In a retrospective study, a cohort of 64 OSCC patients was investigated for p63 protein expression and its cellular localization by immunohistochemistry (monoclonal mouse anti-human p63 protein-clone 4A4). After grouping by p63 expression, …
Effect of c-Met expression on survival in head and neck squamous cell carcinoma
2005
The proto-oncogene c-Met has been suggested to be associated with progression of squamous cell carcinoma of the head and neck. The aims of the present study were to assess the prevalence of c-Met expression in oral squamous cell carcinoma (OSCC) and to verify whether c-Met can be considered a marker of prognosis in these patients. In a retrospective study, a cohort of 84 OSCC patients was investigated for c-Met expression and its cellular localization by immunohistochemistry. After grouping for c-Met expression, OSCC patients were statistically analyzed for the variables age, gender, histological grading, tumor node metastasis, staging and overall survival rate. Univariate and multivariate …
Revised risk estimation and treatment stratification of low- and intermediate-risk neuroblastoma patients by integrating clinical and molecular progn…
2014
Abstract Purpose: To optimize neuroblastoma treatment stratification, we aimed at developing a novel risk estimation system by integrating gene expression–based classification and established prognostic markers. Experimental Design: Gene expression profiles were generated from 709 neuroblastoma specimens using customized 4 × 44 K microarrays. Classification models were built using 75 tumors with contrasting courses of disease. Validation was performed in an independent test set (n = 634) by Kaplan–Meier estimates and Cox regression analyses. Results: The best-performing classifier predicted patient outcome with an accuracy of 0.95 (sensitivity, 0.93; specificity, 0.97) in the validation coh…
P-cadherin expression and survival rate in oral squamous cell carcinoma: an immunohistochemical study
2005
Abstract Background P-cadherin (P-cad) is a transmembrane molecule involved in the cell-cell adhesion and similar to E-cadherin (E-cad), but less investigated in oncology, especially in in vivo studies. Aims of the present study were to assess the prevalence of P-cad expression in oral squamous cell carcinoma (OSCC) and to verify whether P-cad can be considered a marker of prognosis in patients with OSCC. Methods In a retrospective study, a cohort of 67 OSCC patients was investigated for P-cad expression and its cellular localization by immunohistochemistry; some respective healthy margins of resection were similarly investigated as standard controls. After grouping for P-cad expression, OS…
Relationship between pulp-tooth volume ratios and chronological age in different anterior teeth on CBCT
2017
Background The CBCT imaging technique exhibits proper accuracy to determine the internal anatomy of teeth. Therefore, this technique can use to estimate age by measuring the amount of decrease in the volume of the pulpal cavity of teeth. The aim of the present study was to evaluate the correlation between chronological age and pulp-to-tooth volume ratios in anterior teeth with the use of the CBCT technique and to determine a regression model to estimate human age. Material and methods In this present descriptive-analytical study, 122 subjects (46 males and 76 females), with an age range of 13-70 years, were evaluated. The MIMICS software program was used to determine the pulp-to-tooth volum…
Prevalence of tooth erosion and associated factors in 13-16-year old adolescents in Greece
2012
Objectives: The aim of this study was to estimate the prevalence of dental erosion and to investigate possible associations among dental erosion and medical history, dietary and lifestyle habits in a sample of adolescents in Greece. Study design: The study sample consisted of 770 adolescents, 374 boys and 396 girls aged 13 to 16 years. All individuals were clinically examined and answered questions regarding their medical history, rate and frequency of drinks and food consumption and lifestyle habits. Statistical analysis of the questionnaire items was performed by using the multiple logistic regression analysis model. Results: Two hundreds and sixty adolescents were diagnosed as having den…