Alzheimer's disease (AD) is associated with decreased brain energy metabolism. Hypometabolism in the posterior cingulate cortex (PCC) occurs before the onset of memory deficits in subjects at genetic risk for AD who are not yet cognitively impaired. There is a specific inhibition in cytochrome oxidase (C.O.) in the PCC, an area involved in spatial navigation. Creating an animal model that exhibits the early pathophysiology of AD is important for developing and testing drugs that could reverse memory problems associated with such deficits. Methylene blue (MB) is a compound that improves C.O. activity and memory retention in rats. This dissertation had three specific aims: 1) to examine if isolated PCC hypometabolism causes spatial memory deficits in rats; 2) to find a dose of MB that improves memory without nonspecific behavioral effects; and 3) to prevent memory deficits from PCC hypometabolism with low dose MB. PCC hypometabolism was produced by focal administration of sodium azide, an inhibitor of C.O. activity. PCC hypometabolism resulted in impaired spatial memory in a hole board food-search task, increased oxidative damage, and neurotoxicity in the PCC. In addition, PCC hypometabolism resulted in reduced inter-regional correlations in brain activity. Our second set of studies examined the dose-response effects of MB. Our findings demonstrated that a low dose of MB: 1) enhanced memory in open field habituation and object recognition tasks; 2) did not affect general locomotor activity, exploration, motivation, or anxiety; and 3) increased brain oxygen consumption 24 hr after in vivo administration. Finally, our last study found that low dose MB prevented the deficits caused by PCC hypometabolism. MB did not prevent PCC inhibition or cell loss caused by sodium azide. Inter-regional correlations of brain metabolic activity suggested that rats treated with MB were using a different, but equally efficient, strategy for memory retrieval. This animal model of C.O. hypometabolism in the PCC can provide information to understand the mechanisms that regulate early pathological degeneration and reveal new therapeutic strategies aimed at reducing or preventing cognitive decline. Studies of low dose MB in humans are needed to examine its effects in AD patients.

The effects of exogenous estrogen administration on aspects of memory and cognition in women were examined in two studies. In Study 1, women receiving estrogen replacement therapy were compared to untreated women on four measures of verbal memory. Those receiving estrogen had significantly better scores on a measure of delayed memory for propositional material. In Study 2, women in the early stages of Alzheimer's Disease (AD) were administered either estrogen or placebo on a double-blind basis for six months. Women given estrogen showed improvement on a measure of verbal memory and spatial attention compared to the placebo controls. The combined results of these studies provide evidence that estrogen enhances aspects of verbal memory in both healthy postmenopausal women and in postmenopausal women in the early stages of AD as measured by neuropsychological tests. These effects might be mediated by actions of estrogen on neuronal morphology and physiology in brain areas important for memory and cognition.

The liquid-to-crystal nucleation temperature is measured for clathrate-forming mixtures of tetrahydrofuran and water using both an automatic lag time apparatus (ALTA) and a ball screening apparatus. Our results are conclusive evidence that no so-called “memory effect” exists. Either the solid form melts fully or it does not. If it does not, then no supercooling is possible on the next cooling down of that sample, and if it does then the second cooling run and freezing on a sample is just as likely to have a colder nucleation temperature as a hotter one.

Ice-associating proteins (IAPs) are proteins that interact directly with ice crystals, either by offering a site for nucleation, i.e. ice nucleating proteins (INPs), or by binding to nascent crystals to prevent addition of more water molecules, i.e. antifreeze proteins (AFPs). AFPs have been found to inhibit the formation of clathrate-hydrates, ice-like crystalline solids composed of water-encaged guest molecules. Study of AFP-hydrate interaction is leading to a greater understanding of AFP adsorption and of the mechanism behind the “memory effect” in hydrates, wherein previously frozen crystals reform more quickly after a brief melt. AFP is currently the only known memory inhibitor. Such a low-dosage hydrate inhibitor (LDHI) is of great interest to the oil and gas industry, as hydrate formation and reformation in the field is a huge problem. Bacterial AFPs, though largely uncharacterized, may be the best candidates for large-scale production of hydrate inhibitors, given the difficulties in obtaining AFP from other sources. The popular kinetic inhibitors (KIs) polyvinylpyrrolidone (PVP) and polyvinylcaprolactam (PVCap) were used for points of comparison in experiments exploring the hydrate-inhibition activity of several ice-associating bacteria and proteins. The addition of the soil microbe, Chryseobacterium, increased the average lag-time to tetrahydrofuran (THF) hydrate formation by 14-fold, comparable to PVP or PVCap. Samples containing Pseudomonas putida, a bacterium having both ice-nucleation protein (INP) and AFP activity, had lag-times double that of the control. Solutions with P. putida and Chryseobacterium sometimes formed hydrate slurries of stunted crystal nuclei instead of solid crystals. No inhibition of memory or nucleation was noted in bacterial assays, however bacteria with INP activity was linked to unusually rapid memory reformation. Quartz crystal microbalance experiments with dissipation (QCM-D) showed that a tight adsorption to SiO2 and resistance to rinsing are correlated with a molecule’s inhibition of hydrate formation and reformation. These results support a heterogeneous nucleation model of the memory effect, and point to the affinity of AFP for heterogeneous nucleating particles as an important component of memory inhibition. / Thesis (Master, Biology) -- Queen's University, 2008-05-30 15:20:38.749

Relationships between the steroid hormones estradiol (E2), testosterone (T), cortisol (CRT) and dehydroepiandrosterone-sulfate (DHEAS), memory and mood were investigated in men, in women estrogen-users and non-users, and in patients with Alzheimer's Disease (AD). In Study 1, 72 year-old healthy men and women estrogen-users performed better than estrogen non-users on Forward and Total Digit Span, which test attention and short-term memory, concomitant with their higher E2 levels. The estrogen-users performed better than the men and the non-users on Delayed Selective Reminding, a test of explicit verbal memory. Men and women with higher CRT levels performed worse on several explicit verbal memory tests compared to those with lower endogenous, CRT levels. In Study 2, male patients with AD performed better than estrogen non-using women with AD on several everyday memory tests, and women estrogen-users with AD performed similarly to the men. Both the men and estrogen-users had higher levels of E2 than the non-users. AD patients with higher endogenous levels of DHEAS performed better than those with lower levels on several everyday memory tests, and AD patients with higher CRT levels were impaired on one aspect of everyday spatial memory, Route Recall. In Study 3, no differences in hormone levels between AD patients and age-matched healthy elderly controls were found. The AD patients were most severely impaired on tasks involving explicit verbal recall compared to healthy controls, and least impaired on short-term memory and concentration tasks. The AD patients reported more dysphoric mood and mental dulling symptoms than healthy age-matched controls, but they did not report feeling less positive about the future. Taken together, these results suggest that higher levels of DHEAS and E2 are related to better memory performance in both healthy elderly men and women and in patients with AD, and higher CRT levels are associated with poorer explicit verbal memory performanc

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Gall, Ken; Committee Chair: May, Gary S; Committee Member: Brand, Oliver; Committee Member: Degertekin, F Levent; Committee Member: Milor, Linda S. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 98-99). Also available via the Internet.

Submitted by Ronildo Prado (ronisp@ufscar.br) on 2017-08-22T18:30:41Z No. of bitstreams: 1 DissRWS.pdf: 6193084 bytes, checksum: 3bdd1b505e2e63b3865d89c32053e44b (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-22T18:30:49Z (GMT) No. of bitstreams: 1 DissRWS.pdf: 6193084 bytes, checksum: 3bdd1b505e2e63b3865d89c32053e44b (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-08-22T18:30:56Z (GMT) No. of bitstreams: 1 DissRWS.pdf: 6193084 bytes, checksum: 3bdd1b505e2e63b3865d89c32053e44b (MD5) / Made available in DSpace on 2017-08-22T18:31:02Z (GMT). No. of bitstreams: 1 DissRWS.pdf: 6193084 bytes, checksum: 3bdd1b505e2e63b3865d89c32053e44b (MD5) Previous issue date: 2014-08-29 / Não recebi financiamento / The shape memory effect represents a physical property of materials with great potential applications in several sectors of Industry. In metallic materials, it’s a phenomenon associated to martensitic transformation and its reversion process in which the material, after being deformed over its elastic limit, can reestablish its original form through heat treatment. It’s really worthwhile to explore this feature because it allows the fabrication of joints and pipe coupling joints without the use of welds. The stainless Fe-Mn-Si-Cr-Ni alloys which this property are potentially eligible for this application and thus have attracted attention of researchers because they’re a cheap economical alternative and easy to be produced when compared to copper and Nickel-Titanium alloys with shape memory shape effect. However, these stainless alloys still feature discrete values of shape recovery and limited corrosion resistance. Besides that, the fabrication processes of this alloys reported in literature involve the production through induction vacuum furnaces that add great cost to the final product and imply few engineering applications. In this regard, the present work aimed to contribute to the study of Fe-Mn-Si-Cr-Ni alloys with shape memory effect and creating and characterizing an alloy obtained by fusion in inductions furnace without controlled atmosphere, assessing the different conditions of material processing when in terms of microstructure, mechanical properties, degree of shape recovery and corrosion resistance. The fusion of the alloy has generated an ingot with a high level of non-metallic inclusions and a certain amount of interdendritic porosity as well as the formation of secondary phases in the microstructure. The homogenization treatment has dropped some of the secondary phases, but the air cooling generated precipitation in grain boundaries. In the heat-treated condition, the alloy featured better results in terms of shape recovery and corrosion resistance. / O efeito de memória de forma representa uma propriedade física dos materiais com grande potencial para aplicações em diversos setores da indústria. Nos materiais metálicos, trata-se de um fenômeno associado à transformação martensítica e seu processo de reversão no qual o material, após ser deformado acima de seu regime elástico, consegue reestabelecer sua forma original mediante aquecimento. Essa característica é interessante de ser explorada, pois possibilita a fabricação de junções e sistemas de acoplamento de tubulações sem solda. As ligas inoxidáveis Fe-Mn-Si-Cr-Ni que apresentam essa propriedade são candidatas em potencial para essa aplicação e têm atraído a atenção de pesquisadores por ser uma alternativa econômica e de fácil produção quando comparadas as ligas com memória de forma à base de cobre ou níquel-titânio. No entanto, essas ligas inoxidáveis ainda apresentam valores discretos de recuperação de forma e resistência à corrosão limitada. Além disso, os processos de fabricação de ligas dessa natureza relatados na literatura envolvem a produção em fornos de indução a vácuo, o que agrega alto custo ao produto final e implica em poucas aplicações de engenharia. Nesse tocante, o presente trabalho visou contribuir para o estudo de ligas Fe-Mn-Si-Cr-Ni com memória de forma elaborando e caracterizando uma liga obtida por meio de fusão em forno de indução sem atmosfera controlada, avaliando-se as diferentes condições de processamento do material em termos de microestrutura, propriedades mecânicas, grau de recuperação de forma e resistência à corrosão. A fusão da liga gerou um lingote com alto nível de inclusões e certa quantidade de porosidades interdendríticas, além da formação de fases secundárias na microestrutura. O tratamento de homogeneização eliminou algumas das fases secundárias, mas o resfriamento ao ar gerou a precipitação em contornos de grão. Na condição trabalhada a quente, a liga apresentou os melhores resultados em termos de recuperação de forma e resistência à corrosão.

Made available in DSpace on 2015-05-08T14:59:38Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1749141 bytes, checksum: 1c9c3eb30ef41e016293911f596e4898 (MD5) Previous issue date: 2012-03-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The alloys Cu 78,3% - Al 9,8% - Mn 11,9 and 77.5% Cu - Al 9.8% - Mn 11,9% -% Nb 0.5 - 0.3% Ni (wt%) were prepared without the use of protective atmosphere. The first alloy was characterized using optical microscopy, scanning electron microscopy, differential scanning calorimetry and X-ray diffraction and its mechanical property was determinated by the tensile test, quantification of the shape memory effect and superelasticity. In the case of alloy with Nb and Ni, this was characterized by optical microscopy, differential scanning calorimetry and had their mechanical properties determined by tensile testing. / As ligas Cu 78,3% - Al 9,8% - Mn 11,9 e Cu 77,5% - Al 9,8% - Mn 11, 9% - Nb 0,5% - Ni 0,3% (% em peso) foram elaboradas sem utilização de atmosfera de proteção. A primeira liga foi caracterizada através de microscopia ótica, microscopia eletrônica de varredura, Calorimetria Diferencial de Varredura e difração de raios-X e suas propriedades mecânicas foram determinadas através de ensaio de tração, quantificação de efeito de memória de forma e superelasticidade. No caso da liga com Nb e Ni, esta foi caracterizada por microscopia ótica, Calorimetria Diferencial de Varredura e teve suas propriedades mecânicas determinadas através de ensaio de tração.

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