Pulmonary hypertension syndrome (PHS) in broiler chickens adequately represents idiopathic pulmonary arterial hypertension (IPAH) in humans, a condition that affects 300 new patients each year in the US. The factors that trigger IPAH are poorly understood but an increase in reactive oxygen species in the circulation coincides with the onset of these conditions. Broiler chickens (n=583) were fed a control diet (CTL), containing 3,200 kcal of ME / kg of feed, 23% CP, 1.55% (wt / wt) Arginine (Arg) and 40 IU of VE (alpha-tochopherol) / kg of feed; a high-Arg diet (HA), CTL diet plus 0.8% (wt / wt) supplemental L-Arg HCl; or a high Arg and vitamin diet (AEC), the HA diet plus 200 IU ?-tochopherol / kg of feed and 500 mg of ascorbic acid / L of drinking water 500 mg ascorbic acid / L of water (exp. 1 and 2) or Kg feed (exp. 3). Supplemented broilers were either exposed to hypobaric hypoxia or had a primary bronchus occluded (PBO) to induce PHS. Also, medial thickness was assessed in male broiler and Leghorn (n =80) chickens fed a CTL diet and subjected to pulmonary artery occlusion (PAO). The results show that supplementation with Arg and VE plus VC have an additive effect on the velocity at which the pulmonary arterial pressure returned to basal levels in hypoxic chickens challenged with epinephrine. Also, supplementation increased xanthine oxidase (XO) activity in the vicinity of the pulmonary endothelium with no effect on NAD(P)H-oxidase activity or oxidative stress in hypoxic chickens subjected to PBO. These enzymes are upregulated in humans with IPAH. Furthermore, supplementation reduced pulmonary artery reactivity to phenylephrine in hypoxemic broilers. Unsupplemented broiler chickens had a lower specific lung weight compared to unsupplemented Leghorns. Hypoxemic broilers showed thicker resistant pulmonary arteries and were more hypertensive than hypoxemic Leghorns. Leghorns were more hypoxemic and resistant to PHS than broilers. In conclusion, Arg and VE plus VC show an additive effect in the improvement of cardiovascular performance of hypoxemic broilers as well as in restoring reactivity to phenylephrine in hypoxemic pulmonary rings. Also, supplementation shows an additive effect in restoring XO activity in hypoxic broilers. Leghorns had a better ventilation capacity and better pulmonary vasodilation capacity than broiler chickens.

This study investigates a phenomenon that I have termed occlusion inhibition. This research and a small number of earlier studies suggest that, in some experimental conditions, when an attended (target) object is partially occluded by a distractor object, there is less attention allocated to the occluded region of the target object than to the visible parts of that object. In the literature, there are mixed results concerning this attentional effect. Some studies find it and others do not. This study investigates the differences between those conflicting studies with the goal of identifying the factor or factors that govern when occlusion inhibition occurs. Evidence is presented to rule out a number of potentially relevant factors such as depth perception, figural complexity, set size, the use of real world vs. abstract geometric objects, the position of occlusion, the number of overlaps in the display, and the adoption of the attend-object paradigm over the spatial cueing paradigm. After all these factors are ruled out, Experiments 3 and 4 provide evidence for a factor that does determine whether occlusion inhibition occurs or not. These two experiments differ only in the fact that participants are required to report the border color of the target object in Experiment 3 and not in Experiment 4. This task was designed to ensure that participants fully attend to the target object. Occlusion inhibition occurs when the target color is reported, but not when no target color report is required. Removing the target reporting task was found to be an effective means of turning occlusion inhibition on and off. The results of these experiments suggest that, if occlusion inhibition is to take place, attentional selection of overlapping figures requires the target object to be fully processed. This conclusion in turn suggests that attention does not automatically exclude the irrelevant portions of occluded objects, but that attention selects the entire location of the object and then, through reiterative feedback mechanisms, fine tunes the information to inhibit areas that do not belong to the object.

Thesis (M.S.)--University of Michigan, 1970.

Thesis (M.S.)--University of Michigan, 1988.

Thesis (M.S.)--University of Michigan, 1989.

Thesis (M.S.)--University of Michigan, 1970.

Thesis (M.S.)--University of Michigan, 1975.

Thesis (M.S.)--University of Michigan, 1988.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains viii, 55 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-55).

Um fator importante no estudo da oclusão refere-se à correta detecção da presença de contatos oclusais no lado de balanceio, sua intensidade e localização. No entanto, a maioria dos estudos que se propuseram a detectar a presença de contatos em balanceio, o fizeram utilizando papel carbono em movimentos conduzidos de máxima intercuspidação até topo-a-topo. O objetivo deste estudo foi estudar a frequência de contatos oclusais detectados no lado de balanceio em 42 indivíduos jovens, com idade média de 26 anos comparando dois métodos: 1- durante o ato mastigatório, utilizando como material de registro uma mistura de verniz cavitário e pó de fosfato de zinco; 2- durante movimentos conduzidos, utilizando como material de registro papel carbono. A frequência de contatos oclusais no lado de balanceio durante o ato mastigatório e utilização de verniz, foi de 100%, sendo que 97 % dos pacientes possuíam contatos bilaterais e 3 % apresentaram apenas contatos unilaterais. A frequência de contatos oclusais no lado de balanceio para os mesmos indivíduos, porém, com a utilização de papel carbono e movimentos conduzidos foi de 76%, sendo que 64% dos pacientes possuíam contatos bilaterais, 12% apresentavam apenas contatos unilaterais e 24% dos pacientes não possuíam contatos. Com relação aos métodos empregados, a mistura de verniz cavitário e pó do fosfato de zinco mostrou um número maior estatisticamente significante de marcações comparado ao papel carbono. De acordo com a metodologia empregada, concluiu-se que o verniz se mostrou mais sensível e eficaz por detectar uma quantidade maior de contatos oclusais comparado ao papel carbono. / An important factor in the study of occlusion refers to the correct detection of the occlusal contacts in the balancing side, intensity and location. However, most studies that proposed itself on detect the presence of balancing contacts used carbon paper led movements in maximal intercuspal to topo a topo. The objective of this study was to evaluate the frequency of occlusal contacts in the balancing side in 42 young people, with a mean age of 26 years through two methods: 1 - during the masticatory act, using as registration material a mixture of cavity varnish and dust zinc phosphate, 2 - during movements performed, using as registration material carbon. And assess if the methods show similar results. The frequency of occlusal contacts on the balancing side during the masticatory act and using of varnish, was 100% and 97% of patients had bilateral contacts and 3% had presented only unilateral contacts. The frequency of occlusal contacts on the balancing side for the same individuals, however, by analyzing method with carbon and led movements was 76% and 64% of patients had bilateral contacts, 12% had only unilateral and 24 contacts % of patients had no relation to contacts. Regarding the method study, it presented statistical differences between the methods, regardless of the side studied. All differences point to a greater number of contacts on the coating method, indicating that in general this method detects more markings than the carbon method. According to the methodology, it concluded that the method was more sensitive varnish that carbon method for being able to detect more numbers occlusal contacts than carbon.