Thesis (M.A.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.A.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vi, 54 p. : ill. Includes abstract. Includes bibliographical references.

Thesis (Ph.D.) - Carleton University, 2002. / Includes bibliographical references (p. 137-180). Also available in electronic format on the Internet.

A considerable amount of research has shown that a severe dietary deficiency of protein or vitamins will markedly depress antibody synthesis. Very little work has been done with the effect of mineral deficiencies on antibody production, and no evidence has been presented showing the relationship of the effects of small changes in nutrient intake to the sensitivity of the antibody response to small degrees of malnutrition and the relationship of dietary iron, calcium and vitamin D to the production of antibodies. In two experiments, it was shown that as the level of iron in the diet is decreased, the production of antibodies is decreased proportionally. In the first iron experiment, 42, weanling male rats were given 7 levels of iron ranging from 20 to 5 mg Fe/kg diet. Antibody titer after immunization with tetanus toxoid was decreased proportionally from 88 to 17. In a second iron experiment, 10 raths were given either 10 or 0 mg Fe/kg diet and their titers to tetanus toxoid were 340 and 19 respectively. In another two experiments, it was found that the level of dietary calcium makes little or no significant difference on antibody production, when fed either with or without vitamin D. In the first calcium experiment, 20 rats were given either 6.3, 4.4. or 3.2 gm Ca/kg diet and their antibody titers after tetanus toxoid immunization ranged from 88 to 55. in the final calcium study, 50 rats were divided into ten groups and given five different levels of dietary calcium ranging from 6.3 to 1.3 gm Ca/kg diet. Half of each dietary group was given adequate vitamin D and vitamin D was withheld from the other half. In this experiment, antibody titers to tetanus toxoid ranged from 90 to 110. From the results of these experiments, it is apparent that dietary iron plays an important role in the synthesis of antibodies and thus in the maintainance of resistance against infectious disease. It is also evident that the antibody response is sensitive to different degrees of malnutrition, with antibody production being decreased proportionally to the severity of the dietary deficiency.

Made available in DSpace on 2016-04-29T13:18:10Z (GMT). No. of bitstreams: 1 Mariana Queiroz Martins Pedroso.pdf: 1093596 bytes, checksum: 07eb393466b02df8274ee63254b1d002 (MD5) Previous issue date: 2005-05-16 / Replicating Iversen s (1993) procedure, this study s goal was to increase the comprehension of the running response of rats on an activity wheel when running was a consequence of responding on a fixed-ratio schedule. The study also explored the impact of a restricted period of food availability on the reinforcing value of wheel running. Body weight, food and water consumption of six female rats were systematically measured. Five subjects were also submitted to a procedure designed to install wheel-running as a consequence for lever pressing. After baseline measures of wheel running, a gradual restriction of the session time when wheel-running was possible was implemented, followed by the shaping of a lever pressing response reinforced by wheel-running, and a phase when lever pressing was maintained by intermittent reinforcement on a FR. The FR values initially were increased automatically and later the FR values were increased based on the analysis of the subject s responses. One subject was finally submitted to an extinction procedure of the lever pressing response. The availability of food also varied during experimental phases concomitantly with the manipulation of lever pressing and wheel running: food was initially available all the time, later food was available for 90 minutes daily, and, finally, it was available all the time again for some subjects.. Results indicated that the lever pressing that produced wheel running as a consequence was acquired and maintained for 4 of 5 subjects. Nevertheless these responses were emitted at low rates, and were acquired only after a long training. For one subject, the lever pressing response was acquired only when food was its consequence and was, then maintained when the consequence became wheel-running. Results also showed that rate of lever pressing and the number of wheel turns decreased as the value of fixed ratio increased, and that weight loss did not depend on the number of wheel turns, but seemed to depend on the time restriction of food availability. It is discussed that for 3 subjects the time restriction of food availability was an establishing operation for wheel-running / Similar ao procedimento de Iversen (1993), este estudo buscou compreender o funcionamento da resposta de andar na roda como reforço, em esquema de reforçamento em FR e explorou o impacto da restrição do tempo de alimento disponível sobre o valor reforçador de andar na roda. Seis ratas foram submetidas à linha de base de peso corporal, consumo de alimento e água. Destas, cinco foram designadas às seguintes fases tendo a possibilidade de andar na roda: sessões de linha de base, redução gradual do tempo de possibilidade de andar na roda; modelagem da resposta de pressão à barra; reforçamento intermitente em FR com aumento automático do valor da FR, aumento do valor da FR determinado pela análise das respostas emitidas pelos sujeitos e extinção da resposta de pressão à barra. Sobre o alimento, destacam-se as seguintes condições: alimento disponível por tempo integral, 90 de alimento disponível por dia e alimento por tempo integral. Tais condições acompanharam as manipulações das variáveis relativas a andar na roda. Os resultados apontaram que quatro de cinco sujeitos adquiriram com muito treino e mantiveram com taxas baixas a resposta de pressão à barra tendo a possibilidade de andar na roda como conseqüência, diferente do obtido por Iversen (1993). Para um sujeito, inclusive a resposta de pressão à barra só foi instalada usando alimento como reforço, e depois mantida com a resposta de andar na roda. Observou-se também que as taxas de respostas de pressão à barra e o número de voltas na roda diminuíram com o aumento do valor da FR, e que a perda de peso dos sujeitos não dependeu da quantidade de voltas na roda e sim da restrição do tempo de alimento disponível. Pode-se dizer que a restrição do tempo de alimento foi uma operação estabelecedora que alterou a efetividade reforçadora do andar na roda para quatro dos sujeitos