Search results for "regres"

Molecular topology: A new strategy for antimicrobial resistance control

2017

The control of antimicrobial resistance (AMR) seems to have come to an impasse. The use and abuse of antibacterial drugs has had major consequences on the genetic mutability of both pathogenic and nonpathogenic microorganisms, leading to the development of new highly resistant strains. Because of the complexity of this situation, an in silico strategy based on QSAR molecular topology was devised to identify synthetic molecules as antimicrobial agents not susceptible to one or several mechanisms of resistance such as: biofilms formation (BF), ionophore (IA) activity, epimerase (EI) activity or SOS system (RecA inhibition). After selecting a group of 19 compounds, five of them showed signific…

Two-Stage Bayesian Approach for GWAS With Known Genealogy

2019

Genome-wide association studies (GWAS) aim to assess relationships between single nucleotide polymorphisms (SNPs) and diseases. They are one of the most popular problems in genetics, and have some peculiarities given the large number of SNPs compared to the number of subjects in the study. Individuals might not be independent, especially in animal breeding studies or genetic diseases in isolated populations with highly inbred individuals. We propose a family-based GWAS model in a two-stage approach comprising a dimension reduction and a subsequent model selection. The first stage, in which the genetic relatedness between the subjects is taken into account, selects the promising SNPs. The se…

Stagewise pseudo-value regression for time-varying effects on the cumulative incidence

2015

In a competing risks setting, the cumulative incidence of an event of interest describes the absolute risk for this event as a function of time. For regression analysis, one can either choose to model all competing events by separate cause-specific hazard models or directly model the association between covariates and the cumulative incidence of one of the events. With a suitable link function, direct regression models allow for a straightforward interpretation of covariate effects on the cumulative incidence. In practice, where data can be right-censored, these regression models are implemented using a pseudo-value approach. For a grid of time points, the possibly unobserved binary event s…

LEGO-based generalized set of two linear algebraic 3D bio-macro-molecular descriptors: Theory and validation by QSARs

2019

Abstract Novel 3D protein descriptors based on bilinear, quadratic and linear algebraic maps in R n are proposed. The latter employs the kth 2-tuple (dis) similarity matrix to codify information related to covalent and non-covalent interactions in these biopolymers. The calculation of the inter-amino acid distances is generalized by using several dis-similarity coefficients, where normalization procedures based on the simple stochastic and mutual probability schemes are applied. A new local-fragment approach based on amino acid-types and amino acid-groups is proposed to characterize regions of interest in proteins. Topological and geometric macromolecular cutoffs are defined using local and…

Search of Chemical Scaffolds for Novel Antituberculosis Agents

2005

3 A method to identify chemical scaffolds potentially active against Mycobacterium tuberculosis is presented. The molecular features of a set of structurally heterogeneous antituberculosis drugs were coded by means of structural invariants. Three tech- niques were used to obtain equations able to model the antituberculosis activity: linear discriminant analysis, multilinear re- gression, and shrinkage estimation-ridge regression. The model obtained was statistically validated through leave-n-out test, and an external set and was applied to a database for the search of new active agents. The selected compounds were assayed in vitro, and among those identified as active stand reserpine, N,N,N…

Revealing the relationship between vegetable oil composition and oxidative stability: A multifactorial approach

2018

Abstract A detailed composition analysis was performed for 22 diverse oils and fats and included determination of tocopherols (α, γ and δ), β-carotene, chlorophyll, total phenolic compounds (TPC) and fatty acid (FA) composition, as well as the determination of their oxidative stability (Rancimat test). Principal components analysis was applied to obtain an overview of the sample variations and to identify behavioural patterns. Linear regression correlations and a multiple linear regression model were performed to quantify the relationship between the composition of oils and fats and their oxidative stability. The TPC and saturated FA were the main individual factors that correlated positive…

Virological response and retention in care according to time of starting ART in Italy: data from the Icona Foundation Study cohort

2020

Abstract Objectives To describe: (i) factors associated with rapid and delayed ART initiation; (ii) rates of 12 week virological response; and (iii) virologically controlled retention in care by 1 year from ART initiation according to timing of start in a real-life setting. Methods All individuals in the Icona cohort diagnosed with HIV in 2016–17 who initiated ART were grouped according to the time between HIV diagnosis and ART initiation: Group 1, ≤7 days; Group 2, 8–14 days; Group 3, 15–30 days; Group 4, 31–120 days; and Group 5, >120 days. Multivariable logistic regression models were used to identify factors associated with: (i) the probability of rapid (Group 1) and very delayed…

Influence of the dental prosthetic status on self-perceptions of health and treatment needs : a cross-sectional study of middle-aged adults with chro…

2018

Background Subjective aspects of dental prosthesis need in middle-aged adults are poorly explored, especially when the population presents chronic diseases. Objectives: To investigate if the use and necessity of dental prosthesis influence the self-perceptions of health and dental treatment need in middle-aged adults with chronic diseases. Material and Methods A cross-sectional study was performed in 210 middle-aged adults. Socio-demographic aspects, dental services use, oral and general perceptions of health, dental treatment need and OIDP were assessed using a standardized questionnaire. One trained dentist evaluated the use and necessity of dental prosthesis. Data were analyzed using Chi…

2019

Purpose This study analyzed whether low birth weight is linked to prevalence and incidence of age-related maculopathy (AMD) in adulthood. Methods The Gutenberg Health Study (GHS) is a population-based, observational cohort study in Germany. GHS participants at an age from 35 to 74 years were included. An ophthalmologic examination with fundus photography was carried out. Fundus photographs were graded according to the Rotterdam Grading Scheme for AMD at baseline and at the 5-year follow-up examination. Participants were divided into three different birth weight groups (low: 4000 g). Poisson regression analysis with adjustment for several confounders was used to assess associations between b…

Analysis of the morphological dynamics of blastocysts after vitrification/warming: defining new predictive variables of implantation

2017

Objective To describe the morphological dynamics of vitrified/warmed blastocysts and to identify quantitative morphological variables related to implantation. Subsequently, by using the most predictive parameters, to develop a hierarchical model by subdividing vitrified/warmed blastocysts into categories with different implantation potentials. Design Observational, retrospective, cohort study. Setting University-affiliated private IVF center. Patient(s) The study included 429 vitrified/warmed blastocysts with known implantation data, which were evaluated by time-lapse imaging. Blastocysts were routinely placed in EmbryoScope (Vitrolife) immediately after warming until transfer. Intervention…