Search results for "theoretical"
showing 10 items of 11439 documents
Stress-Related Dysfunction of Adult Hippocampal Neurogenesis—An Attempt for Understanding Resilience?
2021
Newborn neurons in the adult hippocampus are regulated by many intrinsic and extrinsic cues. It is well accepted that elevated glucocorticoid levels lead to downregulation of adult neurogenesis, which this review discusses as one reason why psychiatric diseases, such as major depression, develop after long-term stress exposure. In reverse, adult neurogenesis has been suggested to protect against stress-induced major depression, and hence, could serve as a resilience mechanism. In this review, we will summarize current knowledge about the functional relation of adult neurogenesis and stress in health and disease. A special focus will lie on the mechanisms underlying the cascades of events fr…
Interferon-Beta Therapy of Multiple Sclerosis Patients Improves the Responsiveness of T Cells for Immune Suppression by Regulatory T Cells
2015
Multiple sclerosis (MS) is an inflammatory autoimmune disease characterized by imbalanced immune regulatory networks, and MS patient-derived T effector cells are inefficiently suppressed through regulatory T cells (Treg), a phenomenon known as Treg resistance. In the current study we investigated T cell function in MS patients before and after interferon-beta therapy. We compared cytokine profile, responsiveness for Treg-mediated suppression ex vivo and evaluated reactivity of T cells in vivo using a humanized mouse model. We found that CD4+ and CD8+ T cells of therapy-naive MS patients were resistant to Treg-mediated suppression. Treg resistance is associated with an augmented IL-6 product…
Cross-Cultural Comparison of American and Finnish College Students' Exercise Behavior Using Transtheoretical Model Constructs
2004
Although the benefits of exercise are well documented, an international problem of physical inactivity exists. More research, especially theory based, has been recommended. One promising approach for studying exercise behavior is that proposed in the Transtheoretical Model (TTM) of behavior change. This model, however, has received minimal cross-cultural attention and, relative to the current study, measurement instruments have only recently been translated into the Finnish language. The purpose of this study was to assess American and Finnish college students' exercise behaviors on the basis of TTM. Participants were American (n = 169) and Finnish (n = 168) college students who completed l…
Visual simulation through different intraocular lenses using adaptive optics: Effect of tilt and decentration
2011
Purpose To analyze visual quality differences between intraocular lenses (IOLs) and assess the impact of IOL decentration and tilt on visual quality. Setting University of Valencia, Valencia, Spain. Design Cohort study. Methods The crx1 adaptive optics visual simulator was used to simulate the wavefront aberration pattern of 2 commercially available aspheric aberration-correcting IOLs (Acrysof IQ SN60WF and Tecnis ZA9003) and 2 spherical IOLs (Akreos Adapt and Triplato) in 5 situations: centered, decentered 0.2 mm and 0.4 mm, and tilted 2 degrees and 4 degrees. Monocular distance visual acuity at 100%, 50%, and 10% contrast and the depth of focus were measured. Results Ten eyes of 10 patien…
Knockdown of NANOG Reduces Cell Proliferation and Induces G0/G1 Cell Cycle Arrest in Human Adipose Stem Cells
2019
The core components of regenerative medicine are stem cells with high self-renewal and tissue regeneration potentials. Adult stem cells can be obtained from many organs and tissues. NANOG, SOX2 and OCT4 represent the core regulatory network that suppresses differentiation-associated genes, maintaining the pluripotency of mesenchymal stem cells. The roles of NANOG in maintaining self-renewal and undifferentiated status of adult stem cells are still not perfectly established. In this study we define the effects of downregulation of NANOG in maintaining self-renewal and undifferentiated state in mesenchymal stem cells (MSCs) derived from subcutaneous adipose tissue (hASCs). hASCs were expanded…
Noise estimation from averaged diffusion weighted images: Can unbiased quantitative decay parameters assist cancer evaluation?
2013
Purpose Multiexponential decay parameters are estimated from diffusion-weighted-imaging that generally have inherently low signal-to-noise ratio and non-normal noise distributions, especially at high b-values. Conventional nonlinear regression algorithms assume normally distributed noise, introducing bias into the calculated decay parameters and potentially affecting their ability to classify tumors. This study aims to accurately estimate noise of averaged diffusion-weighted-imaging, to correct the noise induced bias, and to assess the effect upon cancer classification. Methods A new adaptation of the median-absolute-deviation technique in the wavelet-domain, using a closed form approximati…
Modeling of Human Posturokinetic Movements by a Linear Feedback System: Relations among Feedback Coefficients
2002
This study describes a method of modeling human trunk and whole body backward bending and suggests a possible neural control strategy. The hypothesis was that the control system can be modeled as a linear feedback system, in which the torque acting at a given joint is a function of the state variables (angular positions and angular velocities). The linear system enabled representation of the feedback system by a gain matrix. The matrix was computed from the kinematics recorded by a movement analysis system and from the joint torques calculated by inverse dynamics. To validate the control model, a comparison was made between the angular kinematics yielded by the model and the experimental d…
Tailored screening and dedicated funding for direct acting antiviral drugs: How to keep Italy on the road to hepatitis C virus elimination?
2020
Background and aims. Hepatitis C virus (HCV) elimination for Italy is an ambitious, but achievable goal. In Italy, there is political will, which aims to achieve the World Health Organization (WHO) elimination goals recognizing the need to identify undiagnosed individuals in key high-risk groups and in the general population, however there is concern regarding HCV treatment implementation in Italian Regions. Methods. A modelling analysis was conducted, using the “Italy Polaris” model, to forecast the impact of different HCV treatment rates in achieving the HCV elimination goals in Italy. The model assessed two treatment scenarios: 2018 Scenario and 2019 Scenario, using the annually HCV trea…
The Attentional Demand of Automobile Driving Revisited: Occlusion Distance as a Function of Task- Relevant Event Density in Realistic Driving Scenari…
2014
Objective: We studied the utility of occlusion distance as a function of task-relevant event density in realistic traffic scenarios with self-controlled speed. Background: The visual occlusion technique is an established method for assessing visual demands of driving. However, occlusion time is not a highly informative measure of environmental task-relevant event density in self-paced driving scenarios because it partials out the effects of changes in driving speed. Method: Self-determined occlusion times and distances of 97 drivers with varying backgrounds were analyzed in driving scenarios simulating real Finnish suburban and highway traffic environments with self-determined vehicle speed…
Comparison of prognostic models in patients with advanced Hodgkin disease
2001
Several prognostic systems have been elaborated for patients with Hodgkin disease (HD) over the last 12 years, but early identification of a reasonably large group of both low and high risk, advanced stage patients remains unsatisfactory.Seven well known models were applied to 516 patients with advanced HD, with 315 patients used for the study sample and 201 patients used for the test sample. Individual performances as well as joint performances were analyzed univariately and multivariately in relation to overall survival, recurrence free survival, and time to treatment failure by means of a proportional hazards model.None of the models identified a group containing10% of patients from the …