Search results for " Models"

A key role for cyclic nucleotide gated (CNG) channels in cGMP-related retinitis pigmentosa.

2011

The rd1 natural mutant is one of the first and probably the most commonly studied mouse model for retinitis pigmentosa (RP), a severe and frequently blinding human retinal degeneration. In several decades of research, the link between the increase in photoreceptor cGMP levels and the extremely rapid cell death gave rise to a number of hypotheses. Here, we provide clear evidence that the presence of cyclic nucleotide gated (CNG) channels in the outer segment membrane is the key to rod photoreceptor loss. In Cngb1(-/-) x rd1 double mutants devoid of regular CNG channels, cGMP levels are still pathologically high, but rod photoreceptor viability and outer segment morphology are greatly improve…

Dynamics, alterations, and consequences of minimally invasive intraocular pressure elevation in rats.

2014

PURPOSE: An important, yet not exclusive, aspect of primary open angle glaucoma is elevated intraocular pressure (IOP) profiles within fluctuations and pressure peaks. The study aimed at establishing minimally invasive methods for recurrent IOP elevation in rats to investigate the impact of IOP dynamics and pathomorphologic retinal alterations during and after IOP elevation. METHODS: Intraocular pressure was elevated unilaterally in Long Evans rats to a level of ≈35 mm Hg for 1 hour in a total of 30 manipulations within 6 weeks, by using two methods: (1) suction-cup oculopression and (2) loop-adjusted oculopression. Retinal thickness (RT) was measured via optical coherence tomography (OCT),…

Retina in various animal models of neuronal ceroid-lipofuscinosis

1992

The childhood forms of human neuronal ceroid-lipofuscinosis (NCL) are invariably associated with a severe progressive retinopathy which commences at the photoreceptor level morphologically and proceeds to a final loss of neuronal cells accompanied by severe gliosis. In respective spontaneous animal conditions of NCL, in English setters, Dalmatian dogs, and New Zealand sheep, retinal involvement is not commensurate although the retina does not seem to be completely unaffected. In canine NCL, there might be functional and electro-physiological impairment of retinal cells, but retinal atrophy is not obvious. In ovine NCL, the retina, apart from accumulating NCL-specific lipopigments within neu…

Retinal neurodegenerative changes in the adult insulin receptor substrate-2 deficient mouse.

2014

Abstract Insulin receptor substrate-2 (Irs2) mediates peripheral insulin action and is essential for retinal health. Previous investigations have reported severe photoreceptor degeneration and abnormal visual function in Irs2-deficient mice. However, molecular changes in the Irs2 − / −  mouse retina have not been described. In this study, we examined retinal degenerative changes in neuronal and glial cells of adult (9- and 12-week old) Irs2 − / −  mice by immunohistochemistry. 9-week old Irs2 − / −  mice showed significant thinning of outer retinal layers, concomitant to Muller and microglial cell activation. Photoreceptor cells displayed different signs of degeneration, such as outer/inner…

Contributions to the study of returns to education : the Tunisian case

2016

In Tunisia, enrollment rates in tertiary education had soared up over the past two decades. A significant increase of student annual flows imposed the implementation of reforms that led to an increase in the number of higher education institutions and universities. One of the challenges in Tunisia and many African countries is to improve the efficiency of education systems to promote employability and graduates employment. This thesis discuss the question of the efficiency of education from an economic approach based on returns to education in the labor market. The first chapter analyses private returns to education particularly higher education in African countries. Our findings highlight …

Risk Analysis of Human Anisakidosis Through the Consumption of the Blue Whiting, Micromesistius poutassou, Sold at Spanish Supermarkets

2012

European legislation directed at the catering industry concerning the prevention of anisakidosis proposes efficient measures to avoid human infestation, but this legislation does not directly address the consumer at the household level. Assessing the anisakidosis risk for consumers who buy fresh fish at supermarkets in Spain, 284 blue whiting, Micromesistius poutassou, specimens, originating from two fishing zones and seasons of capture, sold at five nationwide Spanish supermarket chains, were examined to identify the presence of anisakid species and analyze their prevalence and abundance in viscera and flesh. The potential influence of intrinsic (length and weight) and extrinsic (origin, s…

Model building strategies for risk analysis of perioperative histamine-related cardiorespiratory disturbances.

1995

Tumor response assessment by modified Choi criteria in localized high-risk soft tissue sarcoma treated with chemotherapy.

2012

BACKGROUND. The objective of this study was to compare the prognostic relevance of Response Evaluation Criteria in Solid Tumors (RECIST) versus Choi criteria for the assessment of response in patients with high-risk soft tissue sarcoma of the extremities or trunk wall who received preoperative chemotherapy with or without radiotherapy in a phase 3 trial. METHODS. Patients received 3 cycles of preoperative epirubicin þ ifosfamide with or without radiotherapy. The diagnostic concordance between RECIST and Choi criteria and their correlation with overall survival (OS) and freedom from progression (FFP) were evaluated in a univariate Cox regression model. RESULTS. In 243 of 321 eligible patient…

Stress-strain models for normal and high strength confined concrete: Test and comparison of literature models reliability in reproducing experimental…

2017

SUMMARY: The adoption of proper constitutive laws for confined concrete is basic for seismic assessment of new and existing reinforced concrete civil structures. The deformation capacity of reinforced concrete (RC) columns subjected to axially centred and eccentric loads depends on the effectiveness confinement action. A proper assignment of the stressstrainlaws for concrete allows obtaining an adequate definition of the ductility of the crosssections and correctly identifying mechanical nonlinearities in computational models.Several studies concerning the behaviour of confined concrete have been carried out, highlighting the role of different geometrical and mechanical parameters to the ov…

The Impact of the Direct Participation of Workers on the Rates of Absenteeism in the Spanish Labor Environment.

2020

The aim of this research was to study the relationship between the different levels of direct participation of workers (passive, consultative or active-delegated) in risk prevention management with the levels of absenteeism in Spain. To this end, a transversal study was carried out using microdata from the Second European Survey of Companies on New and Emerging Risks (ESENER-2-Spain, 2014) with a master population of 3162 work centres. A multinomial logistic regression model was carried out, with the dependent variable being the levels of absenteeism and the independent variables, the participation indicators and preventive management, calculating the adjusted odds ratio (aOR) between all t…