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Psychophysical measurements of luminance and chromatic spatial and temporal contrast sensitivity in Duchenne muscular dystrophy

COSTA, Marcelo Fernandes; BARBONI, Mirella Telles Salgueiro; VENTURA, Dora Fix
Fonte: Pontificia Universidade Católica do Rio de JaneiroUniversidade de BrasíliaUniversidade de São Paulo Publicador: Pontificia Universidade Católica do Rio de JaneiroUniversidade de BrasíliaUniversidade de São Paulo
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.187605%
In children with Duchenne muscular dystrophy, color vision losses have been related to dystrophin deletions downstream of exon 30, which affect a dystrophin isoform, Dp260, present in the retina. To further evaluate visual function in DMD children, we measured spatial, temporal, and chromatic red-green and blue-yellow contrast sensitivity in two groups of DMD children with gene deletion downstream and upstream of exon 30. Psychophysical spatial contrast sensitivity was measured for low, middle, and high spatial frequencies with achromatic gratings and for low and middle frequencies with red-green and blue-yellow chromatic gratings. Temporal contrast sensitivity was also measured with achromatic stimuli. A reduction in sensitivity at all spatial luminance contrasts was found for the DMD patients with deletion downstream of exon 30. Similar results were found for temporal luminance contrast sensitivity. Red-green chromatic contrast sensitivity was reduced in DMD children with deletion downstream of exon 30, whereas blue-yellow chromatic contrast sensitivity showed no significant differences. We conclude that visual function is impaired in DMD children. Furthermore, we report a genotype-phenotype relationship because the visual impairment occurred in children with deletion downstream but not upstream of exon 30...

Stapled haemorrhoidopexy transiently decreases rectal compliance and sensitivity

FILHO, F. L. A.; MACEDO, G. M.; SANTOS, A. A. dos; RODRIGUES, L. V.; OLIVEIRA, R. B.; SOUZA, M. A. Nobre e
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.170396%
Aim Stapled haemorrhoidopexy may damage the anorectal musculature and its sensorimotor function. Most studies have not used a barostat for the measurement of compliance. This study aimed to investigate the effect of stapled haemorrhoidopexy on rectal compliance and sensitivity. Method After Ethical Committee approval, we studied 10 male patients (mean age 33.8 years) with third- or fourth-degree haemorrhoids. Rectal compliance and sensitivity were measured with a 600-ml bag and an electronic barostat. Volunteers were submitted to two consecutive rectal distension protocols, including continuous distension at 2, 4 and 6 months after stapled haemorrhoidopexy. Intraluminal volume and pressure were recorded, including the first rectal sensation, desire to defecate and onset of rectal pain. Another group of 10 male control patients (mean age 24.9 years) with pilonidal sinus and no haemorrhoids was also included in the study. Results Two months after stapled haemorrhoidopexy, rectal compliance decreased (7.1 +/- 0.2 vs 5.3 +/- 0.1, 6.4 +/- 0.1 vs 5.1 +/- 0.1 and 5.6 +/- 0.2 vs 4.7 +/- 0.1 ml/mmHg for first rectal sensation, desire to defecate and rectal pain, respectively; P < 0.05). The sensitivity threshold volume did not change for the first sensation but decreased significantly for the desier to defecate and pain (p < 0.05) (116.8 +/- 13.8 vs 148.4 +/- 14.61...

Single intravitreal bevacizumab injection effects on contrast sensitivity in macular edema from branch retinal vein occlusion

Preti, Rony Carlos; Vasquez Ramirez, Lisa Mariel; Gianotti Pimentel, Sergio Luis; Lopes Motta, Augusto Alves; Machado, Cleide Guimaraes; Ribeiro Monteiro, Mario Luiz; Takahashi, Walter Yukihiko
Fonte: CONSEL BRASIL OFTALMOLOGIA; SAO PAULO Publicador: CONSEL BRASIL OFTALMOLOGIA; SAO PAULO
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.170396%
Purpose: To evaluate the effect of a single intravitreal bevacizumab injection on visual acuity, contrast sensitivity and optical coherence tomography-measured central macular thickness in eyes with macular edema from branch retinal vein occlusion. Methods: Seventeen eyes of 17 patients with macular edema from unilateral branch retinal vein occlusion were treated with a single bevacizumab injection. Patients were submitted to a complete evaluation including best corrected visual acuity, contrast sensitivity and optical coherence tomography measurements before treatment and one and three months after injection. Visual acuity, contrast sensitivity and optical coherence tomography measurements were compared to baseline values. Results: Mean visual acuity measurement improved from 0.77 logMAR at baseline to 0.613 logMAR one month after injection (P=0.0001) but worsened to 0.75 logMAR after three months. Contrast sensitivity test demonstrated significant improvement at spatial frequencies of 3, 6, 12 and 18 cycles/degree one month after injection and at the spatial frequency of 12 cycles/degree three months after treatment. Mean +/- standard deviation baseline central macular thickness (552 +/- 150 mu m) reduced significantly one month (322 +/- 127 mu m...

Quartz OSL sensitivity as a proxy for storm activity on the southern Brazilian coast during the Late Holocene

Sawakuchi, André Oliveira; Guedes, C. C. F.; DeWitt, R.; Giannini, Paulo César Fonseca; Blair, M. W.; Nascimento, D. R., Jr.; Faleiros, F. M.
Fonte: ELSEVIER SCI LTD; OXFORD Publicador: ELSEVIER SCI LTD; OXFORD
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.213564%
Natural cycles of irradiation during burial and bleaching due to solar exposure during transport increase the Optically Stimulated Luminescence (OSL) sensitivity of quartz sand grains. The relationship between the OSL sensitivity and sediment transport allows to discriminate quartz sand grains with different depositional histories. In this paper, we evaluate the variation of OSL sensitivity in quartz grains deposited during the progradation of the Ilha Comprida barrier on the southern Brazilian, coast. Changes in sand sensitivity recorded by barrier growth since 6 ka ago are controlled by the variation in the proportion of low versus high sensitivity quartz grains. Low sensitivity grains with short sedimentary history are supplied by the Ribeira de Iguape River and reach the barrier through southward alongshore currents during fair weather conditions. Storm conditions shift the alongshore currents to northeast and permit the transport of high sensitivity grains with long sedimentary history from distal southern coastal sectors to the barrier. Therefore, the input of distal sediments for the Ilha Comprida barrier depends on the frequency and intensity of storms. Thus, the OSL sensitivity can be used as proxy for storm activity. The variation of OSL sensitivity through time indicates that the Ilha Comprida barrier changed from a relatively stable to an unstable storm pattern around 2 ka ago. Periods with increased storm activity peaked around AD 500...

The effect of adhesive and flowable composite on postoperative sensitivity: 2-Week results

Perdigão, Jorge; Anauate-Netto, Camillo; Carmo, André R. P.; Hodges, James S.; Cordeiro, Hiram J. D.; Lewgoy, Hugo R.; Dutra-Corrêa, Maristela; Castilhos, Natália; Amore, Ricardo
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 777-784
Português
Relevância na Pesquisa
36.223594%
Objective: To measure 2-week postoperative sensitivity in Class II composite restorations placed with a self-etching adhesive (Clearfil SE Bond) or a total-etch adhesive (Prime&Bond NT) with or without a flowable composite as cervical increment. Method and materials: Upon approval by the University of Guarulhos Committee on Human Subjects, 100 restorations were inserted in 46 patients who required Class II restorations in their molars and premolars. Enamel and dentin walls were conditioned with a self-etching primer (for Clearfil SE Bond) or etched with 34% phosphoric acid (for Prime&Bond NT). A 1- to 2-mm-thick increment of a flowable composite (Filtek Flow) was used in the proximal box in 50% of the restorations of each adhesive. Preparations were restored with a packable composite (Surefil). The restorations were evaluated preoperatively and 2 weeks postoperatively for sensitivity to cold, air, and masticatory forces using a visual analog scale. Marginal integrity of the accessible margins was also evaluated. Statistical analysis used a mixed linear model with subject as a random effect. Results: Ninety-eight teeth from 44 subjects were observed at 2 weeks. The type of adhesive and use of flowable composite had no significant effects or interaction for any of the four outcomes of interest...

Mesopic radial frequency contrast sensitivity function for young and older adults

Santos,N.A.; Oliveira,A.B.; Nogueira,R.M.T.B.L.; Simas,M.L.B.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2006 Português
Relevância na Pesquisa
36.201743%
The objective of the present study was to determine contrast sensitivity curves of concentric circular patterns with radial frequencies of 0.25, 0.5, 1.0, 2.0, and 4.0 cycles per degree in young and older adult volunteers. These parameters were also compared with sensitivity contrasts for sine-wave gratings. All participants had normal acuity vision and were free of identifiable ocular illness. Contrast sensitivity was measured in 6 young adults aged 19 to 23 years and 6 older adults aged 60 to 69 years using the psychophysical forced-choice method. In this paradigm the volunteers had to decide which of two stimuli contained the above radial frequencies at low contrast levels. The other neutral stimulus was gray with homogeneous luminance. We detected a decline in contrast sensitivity for older adults at all radial frequencies compared to young adults. Also, contrast sensitivity for sine-wave gratings at all measured frequencies was better, as predicted, for all young adults. Maximum sensitivities in the radial frequency contrast sensitivity function and contrast sensitivity function occurred at 0.25 and 0.5 cycles per degree, respectively, for both young and older adults. These results suggest age-related changes in the contrast sensitivity function for concentric symmetrical stimuli.

Psychophysical measurements of luminance and chromatic spatial and temporal contrast sensitivity in Duchenne muscular dystrophy

Costa,Marcelo Fernandes; Barboni,Mirella Telles Salgueiro; Ventura,Dora Fix
Fonte: Pontificia Universidade Católica do Rio de Janeiro; Universidade de Brasília; Universidade de São Paulo Publicador: Pontificia Universidade Católica do Rio de Janeiro; Universidade de Brasília; Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2011 Português
Relevância na Pesquisa
36.187605%
In children with Duchenne muscular dystrophy, color vision losses have been related to dystrophin deletions downstream of exon 30, which affect a dystrophin isoform, Dp260, present in the retina. To further evaluate visual function in DMD children, we measured spatial, temporal, and chromatic red-green and blue-yellow contrast sensitivity in two groups of DMD children with gene deletion downstream and upstream of exon 30. Psychophysical spatial contrast sensitivity was measured for low, middle, and high spatial frequencies with achromatic gratings and for low and middle frequencies with red-green and blue-yellow chromatic gratings. Temporal contrast sensitivity was also measured with achromatic stimuli. A reduction in sensitivity at all spatial luminance contrasts was found for the DMD patients with deletion downstream of exon 30. Similar results were found for temporal luminance contrast sensitivity. Red-green chromatic contrast sensitivity was reduced in DMD children with deletion downstream of exon 30, whereas blue-yellow chromatic contrast sensitivity showed no significant differences. We conclude that visual function is impaired in DMD children. Furthermore, we report a genotype-phenotype relationship because the visual impairment occurred in children with deletion downstream but not upstream of exon 30...

Characterization of spectral sensitivity in two Vancouver Island ecotypes of threespine stickleback (Gasterosteus aculeatus)

Sutton, Michael W
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
36.201743%
Fish tune their visual sensitivity to perform critical tasks and behaviours, such as foraging and mate selection, under the photic conditions encountered in their immediate environment. Photic conditions are influenced by dissolved and particulate matter in water and can differ considerably in intensity and spectrum between environments. Vancouver Island Threespine stickleback (Gasterosteus aculeatus) have diverged into distinct ecological lineages, each experiencing presumably different photic regimes. Stickleback have four visual pigments, corresponding to ultraviolet sensitive (UVS), short wavelength sensitive (SWS), middle wavelength sensitive (MWS) and long wavelength sensitive (LWS) cone photoreceptors. I studied the spectral sensitivity of sticklebacks from a freshwater lake and a nearby marine estuary. Considering the presumed differences between the two photic environments, I hypothesized that ecotypes would exhibit spectral sensitivities that incorporated all four visual pigments, but that ultraviolet sensitivity would differ between ecotypes. Spectral sensitivity was measured using electroretinography, and the peak sensitivities of visual pigments were estimated. Both freshwater and estuarine ecotypes exhibited the previously described four visual pigments...

Ontogeny and topography of retinal polarization sensitivity in rainbow trout (Oncorhynchus mykiss).

Habib-Nayany, Maheen
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
36.232212%
Smoltification induces physiological and behavioural changes in salmonids to prepare them for subsequent changes in diet and habitat. One such change that distinguishes parr (fry) from smolts (juveniles) involves the loss of ultraviolet-sensitive (UVS) cones from the ventral retinal region. Rainbow trout (Oncorhynchus mykiss) can discriminate between different states of polarized light, and can utilize these signals in orientation, navigation, and foraging. Polarization sensitivity is mediated by the UVS (vertical polarization sensitivity), and the medium wavelength/long wavelength sensitive (MWS/LWS, horizontal polarization sensitivity) mechanisms. It is unknown how the loss of UVS cones in the smolt ventral retina affects the ability to detect polarized light. First, spectral sensitivity was measured for both parr and smolts to assess the expression of each cone class in either the ventral or dorsal retinal regions. There was no difference in UV spectral sensitivity between the parr dorsal and ventral retina. In smolts, there was a decrease in UV sensitivity in the ventral region compared to dorsal. As well, there was an increase in long wavelength sensitivity in the ventral region under both background conditions and life stages. Then...

The sensitivity of ultrasound and serum alpha-fetoprotein in population-based antenatal screening for neural tube defects, South Australia 1986-1991

Chan, A.; Robertson, E.; Haan, E.; Ranieri, E.; Keane, R.
Fonte: BLACKWELL SCIENCE LTD Publicador: BLACKWELL SCIENCE LTD
Tipo: Artigo de Revista Científica
Publicado em //1995 Português
Relevância na Pesquisa
36.232212%
OBJECTIVE: To determine the sensitivity of antenatal screening methods for neural tube defects in population-based screening in South Australia in 1986-1991, and whether ultrasound can replace serum alpha-fetoprotein screening in terms of achieving an equivalent level of sensitivity. DESIGN AND SETTING: Ascertainment of all births and terminations of pregnancy with neural tube defects from multiple sources for 1986-1991 in South Australia. Serum and amniotic fluid alpha-fetoprotein results were obtained from the only laboratory performing the tests as a Statewide antenatal screening programme, and information on ultrasound screening from case notifications, hospital case records and medical practitioners who cared for the women. SUBJECTS: All 243 births and terminations of pregnancy with neural tube defects in South Australia in 1986-1991. MAIN OUTCOME MEASURES: The sensitivity of individual screening methods and of all methods used, particularly for spina bifida. RESULTS: For pregnancies with neural tube defects screened by any method (serum alpha-fetoprotein, ultrasound or amniocentesis), 86% sensitivity was achieved. Ultrasound screening for anencephaly achieved 100% sensitivity even in low risk pregnancies, compared with 92% for serum alpha-fetoprotein. For spina bifida...

Neuroendocrine and blood pressure responses to rectal distensions in individuals with high and low visceral pain sensitivity

Elsenbruch, S.; Haag, S.; Lucas, A.; Riemenschneider, N.; Pietsch, A.; Gerken, G.; Heijnen, C.; Schedlowski, M.; Holtmann, G.
Fonte: Pergamon-Elsevier Science Ltd Publicador: Pergamon-Elsevier Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2007 Português
Relevância na Pesquisa
36.201743%
Background: The mechanisms of interindividual variations in visceral pain sensitivity remain poorly understood. We characterized the neuroendocrine responses to rectal distensions in healthy individuals with high vs. low rectal pain sensitivity. Methods: Rectal sensory and pain thresholds were determined, and a series of random painful distensions was carried out. Eighteen subjects were stratified into groups with a low rectal pain threshold (“High Sensitivity” group) vs. a high rectal pain threshold (“Low Sensitivity” group) by median split, and were compared with regard to adrenocorticotropic hormone (ACTH) and cortisol, cardiovascular, and emotional responses. Results: Distensions led to an anticipatory stress response, reflected by elevated baseline anxiety, and increased baseline ACTH and cortisol in both groups. In response to distensions, the “Low Sensitivity” group showed significantly greater ACTH and cortisol concentrations analysis of variance (ANOVA time×group for ACTH: p<.05; for cortisol: p<.01), and elevated diastolic blood pressures (BP) (ANOVA group: p<.01) when compared to the “High Sensitivity” group. Conclusions: Painful rectal distensions are associated with a pronounced anticipatory stress response...

Age-related change in contrast sensitivity among Australian male adults: Florey Adult Male Ageing Study

Sia, I.; Martin, S.; Wittert, G.; Casson, R.
Fonte: Wiley-Blackwell Munksgaard Publicador: Wiley-Blackwell Munksgaard
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
36.201743%
PURPOSE: To describe the age-related change in contrast sensitivity seen in 35- to 80-year-old men in an Australian population. METHODS:  The Florey Adelaide Male Ageing Study (FAMAS) is a prospective population-based study of men aged 35-80 years randomly selected from the north-west suburbs of Adelaide. We conducted a nested ophthalmic substudy of these men. Contrast sensitivity (CS) was measured at four spatial frequencies (3, 6, 12 and 18 cycles/degree [cpd]) using the Vectorvision CSV-1000 contrast sensitivity test chart (Vectorvision, Dayton, OH, USA), and results were statistically analysed relative to age and cataract type. Results:  There were 2650 eligible subjects in the FAMAS and 1195 participated (45.1%); 472 of those participated in the ophthalmic substudy. A statistically significant decrease in contrast sensitivity was seen with advancing age at each spatial frequency tested [Generalized estimating equations (GEE) multiple linear regression: p ≤ 0.01]. The decline with age was greatest in the highest spatial frequency (18 cpd) and least in the lowest spatial frequency (3 cpd). Posterior subcapsular cataract caused the greatest reduction in contrast sensitivity at all spatial frequencies, while nuclear cataract caused significant reduction only in the intermediate (12 cpd) and high (18 cpd) spatial frequencies. Cortical cataract failed to reach statistical significance in contrast sensitivity reduction at all spatial frequencies tested. Conclusion:  Contrast sensitivity declines with age in all spatial frequencies tested with a greater decline occurring in the higher spatial frequencies. Age and cataracts are independently associated with contrast sensitivity decline...

Richtungsempfindlichkeit der Photorezeptoren bei Normalen und Farbenblinden; Cone Directional Sensitivity in Normals, Dichromats and S-Cone-Monochromats

Schulze-Döbold, Claudia
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
36.213564%
Fragestellung: Die Richtungsempfindlichkeit bzw. der Stiles-Crawford-Effekt (SCE) eines Photorezeptors beschreibt Folgendes: ein Lichtstrahl konstanter Intensität wird auf der gleichen Netzhautstelle in Abhängigkeit von seinem Eintrittspunkt durch die Pupille und damit von seiner Richtung unterschiedlich hell wahrgenommen. Vermutlich steht diese Richtungsempfindlichkeit in Zusammenhang mit der Morphologie der Photorezeptoren. Die Photorezeptoren werden mit zunehmender Entfernung von der Fovea kürzer und dicker. Ziel dieser Arbeit war es nun, die Richtungsempfindlichkeit der einzelnen Zapfentypen und Stäbchen bei Normalen und Farbenblinden foveal und bei 10° temporal zu bestimmen. Zum einen sollte damit herausgefunden werden, ob sich beim Normalen die zentrale von der peripheren Richtungsempfindlichkeit unterscheidet und tatsächlich ein Zusammenhang zwischen der Morphologie der Innen- und Außensegmente der Photorezeptoren und der Größe der Richtungsempfindlichkeit besteht. Zum anderen sollte untersucht werden, ob sich die Richtungsempfindlichkeit der Photorezeptoren und damit auch die Morphologie der Photorezeptoren im Auge eines Farbenblinden von der im normalen Auge unterscheidet. Bei Farbenblinden ist mindestens eine Zapfenfunktion ausgefallen...

Zusammenhang zwischen Plasmaadiponektinspiegel und Insulinwirkung auf Glukose-und Fettstoffwechsel; Relationship between plasma concentration of adiponectin and insulin sensitivity in carbohydrate and lipid metabolism

Rahe, Stefanie Anja Felicitas
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
36.187605%
Seit einigen Jahren ist bekannt, daß das Fettgewebe nicht nur eine bloße Energiespeicherfunktion hat, sondern gleichzeitig mit der Sekretion von Fettgewebshormonen, den Adipozytokinen, eine zusätzliche endokrine Rolle einnimmt. Neben Leptin, TNF alpha, PAI-1, Resistin und ASP wurde erst vor kurzem das Adiponektin entdeckt. Bisherige Studienergebnisse haben gezeigt, daß es einen positiven Effekt von Adiponektin auf die Insulinsensitivität im Kohlenhydratstoffwechsel gibt. Auf diese Ergebnisse aufbauend soll in der Tübinger Familienstudie untersucht werden, ob dieser Effekt unabhängig von anderen Parametern ist, die die Insulinsensitivität ebenfalls beeinflussen können, wie Adipositas und Körperfettgehalt. Außerdem soll geklärt werden, ob es auch einen Effekt von Adiponektin auf die Insulinsensitivität im Lipidstoffwechsel gibt. Hierfür wurde in einer multivariaten Regressionsanalyse der Zusammenhang zwischen Adiponektinplasmaspiegel und Insulinsensitivität (gemessen in einem euglykämischen-hyperinsulinämischen Clamp (N=262) und geschätzt aus einem oralen Glukosetoleranztest (N=636)) und Parametern des Lipidstoffwechsels untersucht. Die Plasmaadiponektinkonzentration war positiv mit der Insulinsensitivität im Kohlenhydratstoffwechsel korreliert (OGTT:r=0...

Auswirkungen des Pro12Ala Polymorphismus im PPARy2 Gen und des Gly972Arg Polymorphismus im IRS-1 Gen auf die Insulinsensitivität; Effects of Pro12Ala polymorphism in the PPARy2 gene and the Gly972Arg polymorphism in the IRS-1 gene on insulin sensitivity

Özeker, Mesut
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
36.201743%
Bezüglich des Pro12Ala Polymorphismus im Peroxisome-Proliferator Activated Rezeptor y2 (PPARy2) Gen wurde bereits in einigen, aber nicht allen Studien eine Assoziation mit erhöhter Insulinsensitivität und damit reduziertem Diabetesrisiko dargestellt. Es ist jedoch möglich, dass diese genetische Variation in Interaktion mit einem bestimmten anderen genetischen Hintergrund einen speziellen Effekt auf die Insulinsensitivität zeigt. Diese Studie wurde durchgeführt um die Hypothese zu prüfen, dass die Anwesenheit des Gly972Arg Polymorphismus im Insulin Rezeptor Substrat 1 (IRS-1) bei Trägern des Ala-Allels im PPARy2 Pro12Ala Polymorphismus die Insulinsensitivität in besonderer Weise beeinflusst. Es erfolgte die Bestimmung der Insulinsensitivität an gesunden Probanden und Darstellung dieser in vier Kombinationen von Genotypen, welche durch die An- bzw. Abwesenheit der Polymorphismen im PPARy2 und IRS-1 definiert wurden. Die Insulinsensitivität wurde einmal mittels Berechnung aus den Ergebnissen eines oralen Glukosetoleranztests bestimmt und zusätzlich bei einem Teil dieser Probanden anhand einer hyperinsulinämischen euglykämischen Glukose-Clamp Untersuchung gemessen. Beide Methoden der Insulinsensitivitätsmessung zeigten...

Do Cardiorespiratory Fitness and Abdominal Obesity Mediate the Exercise-Induced Change in Insulin Sensitivity in Older Adults?

Ko, GIFFERD
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
36.213564%
Aging is associated with increased insulin resistance, a condition in which the tissue response to insulin-stimulated glucose uptake is reduced. Insulin resistance is a strong predictor of disease and mortality. Aging is also associated with a decline in physical activity, lower cardiorespiratory fitness (ability to deliver oxygen to active muscles during exercise), and increase in abdominal fat. Both low cardiorespiratory fitness (CRF) and excess abdominal fat are associated with reduced insulin sensitivity in older adults. Improvements in CRF and abdominal obesity through exercise training may be responsible for improvement in insulin sensitivity. Several investigations have reported that changes in CRF and abdominal obesity through exercise are associated with changes in insulin sensitivity. To our knowledge, no prior study has assessed whether change in CRF or abdominal fat alone explains the association between exercise and improvement in insulin sensitivity in older adults. Our findings suggest that improvement in CRF may not explain the exercise-induced change in insulin sensitivity. The improvement in insulin sensitivity from exercise is explained through a decrease abdominal fat that also occurs with exercise. Additionally...

Association between exercise, cardiorespiratory fitness and change in insulin sensitivity

Bostad, William
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
36.239692%
The ability of the body to manage blood sugar is referred to as insulin sensitivity. Reduced insulin sensitivity is both a risk factor and is involved in the pathogenesis of type-2 diabetes. Cardiorespiratory fitness (CRF) is an established predictor of insulin sensitivity. Whether this association persists following control for exercise is not known. The primary objective of this study was to determine the independent associations between changes in exercise, CRF and insulin sensitivity. The influence of changes in body weight and waist circumference (WC) on these associations was examined in secondary analyses. Participants were 140 middle-aged, inactive, abdominally obese adults that participated in a 24-week exercise program. Exercise was performed 5 times per week for the duration of the program and was measured as Calories of energy expended, herein referred to as exercise energy expenditure (exercise EE). CRF was measured using a treadmill test to exhaustion. Body weight was measured on a Detecto scale and WC was measured at the level of the hip bone. Physical activity performed outside of the exercise sessions was measured using portable activity monitors known as accelerometers. Caloric intake was monitored using daily diet records. Following oral consumption of a 75-gram glucose drink...

Toward a broader approach to the study of infant attachment : links between maternal autonomy-support, attachment state of mind, maternal sensitivity, and infant security of attachment

Whipple, Natasha
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
Português
Relevância na Pesquisa
36.187605%
Dans le but d’examiner les mécanismes qui sous-tendent le développement de la sécurité d’attachement chez l’enfant, Grossmann et al. (1999; 2008) proposent une perspective plus vaste de l’étude de l’attachement chez l’enfant, examinant les comportements parentaux pertinents aux deux côtés de l’équilibre entre le système d’attachement et le système d’exploration. La thèse se base sur cette approche pour explorer la relation entre la sécurité d’attachement chez l’enfant et deux comportements maternels, soit la sensibilité maternelle et le soutien à l’autonomie maternel, de même que la relation entre ces deux comportements et l’état d’esprit maternel face à l’attachement. Le premier article propose que la théorie de l’autodétermination, avec ses études empiriques portant sur les comportements parentaux liés à l’exploration, offre une perspective utile pour l’étude des comportements d’exploration dans le cadre de l’équilibre attachement/exploration. L’article présente une revue théorique et empirique des domaines de l’attachement et de la théorie de l’autodétermination et souligne des analogies conceptuelles et empiriques entre les deux domaines, en plus de décrire la façon dont ils se complètent et se complémentent. Le deuxième article étudie les liens entre la sensibilité maternelle...

Sensitivity Analyses in Empirical Studies Plagued with Missing Data

Liublinska, Viktoriia
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation
Português
Relevância na Pesquisa
36.187605%
Analyses of data with missing values often require assumptions about missingness mechanisms that cannot be assessed empirically, highlighting the need for sensitivity analyses. However, universal recommendations for reporting missing data and conducting sensitivity analyses in empirical studies are scarce. Both steps are often neglected by practitioners due to the lack of clear guidelines for summarizing missing data and systematic explorations of alternative assumptions, as well as the typical attendant complexity of missing not at random (MNAR) models. We propose graphical displays that help visualize and systematize the results of sensitivity analyses, building upon the idea of "tipping-point" analysis for experiments with dichotomous treatment. The resulting "enhanced tipping-point displays" (ETP) are convenient summaries of conclusions drawn from using different modeling assumptions about the missingness mechanisms, applicable to a broad range of outcome distributions. We also describe a systematic way of exploring MNAR models using ETP displays, based on a pattern-mixture factorization of the outcome distribution, and present a set of sensitivity parameters that arises naturally from such a factorization. The primary goal of the displays is to make formal sensitivity analyses more comprehensible to practitioners...

Sensitivity kernels for finite-frequency surface waves

Yoshizawa, K; Kennett, Brian
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.201743%
Sensitivity kernels for fundamental mode surface waves at finite frequency for 2-D phase speed and 3-D shear wave speed are constructed based on the Born and Rytov approximations working with a potential representation for surface waves. The use of asymptotic Green's functions for scalar wave equations provides an efficient way to calculate the Born or Rytov kernels. The 2-D sensitivity kernels enable us to incorporate the finite-frequency effects of surface waves, as well as off-great-circle propagation, in tomographic inversions for phase-speed structures. We derive examples of the 2-D sensitivity kernels both for a homogeneous background model (or a spherically symmetric model), and for a laterally heterogeneous model. The resulting distortions of the shape of the sensitivity kernels for a heterogeneous background model indicate the importance of the use of proper kernels to account of the heterogeneity in the real Earth. By combining a set of 2-D sensitivity kernels with 1-D vertical sensitivity kernels for a particular frequency range and taking the inverse Fourier transform, we can derive 3-D sensitivity kernels for surface waves in the time domain. Such 3-D kernels are useful for efficient forward modelling of surface waveforms incorporating finite-frequency effects...