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A lombalgia e a cervicalgia possui grande incidência em toda a população mundial. Segundo a Organização Mundial de Saúde (OMS), em média, cerca de 80% da população adulta apresenta, em algum momento da vida, pelo menos uma queixa de dor na coluna, onde a degeneração da articulação do processo articular é frequentemente apontada como a etiologia. Diversos estudos vêm sendo realizados, na tentativa de se compreender como ocorre o processo degenerativo patológico dessas articulações, onde, frequentemente são usados indivíduos sintomáticos. Deste modo, avaliou-se, com o uso de técnicas macroscópicas, de microscopia de luz e de microscopia eletrônica, a organização estrutural da cartilagem dos processos articulares (CPas) das vértebras cervicais (C) e lombares (L) de indivíduos jovens (GJ) e idosos (GI), presumivelmente assintomáticos. Foram utilizados blocos vertebrais obtidos de cadáveres necropsiados no Serviço de Verificação de Óbitos da Capital do Estado de São Paulo, onde familiares de todos os indivíduos forneceram informações que permitiram incluir ou excluí-los da pesquisa. Os resultados mostram que ocorrem alterações na superfície da CPa do segmento L no GJ. A degeneração da CPa ocorre de forma heterogênea entre os indivíduos do GI e as característica do grau 2 podem ser admitidas como decorrentes do processo de envelhecimento normal, não havendo diferenças entre os segmentos C e L. / Back pain and neck pain have a high occurrence in populations worldwide. According to the World Health Organization (WHO), approximately 80% of adults have at some instance in life pain in the spine with an etiology frequently indicated to be the degeneration of the articular process. Several studies have been undertaken to understand how the pathological degenerative process occurs and symptomatic subjects are frequently used for this end. Macroscopic and light and electron microscopy techniques have been employed to assess the structural organization of the cartilage of the articulation processes (CAP) of the cervical (C) and lumbar (L) vertebrae of presumably asymptomatic young (Y) and elderly (E) people. Samples, retrieved from routinely necropsied corpses by the Death Verification Service of the Capital City of the State of São Paulo (SVOC/SP) and the family of all individuals provided information that enabled include or exclude them from search. Results show that changes in the CAP surface of segment L of Y occur. CAP degradation occurs heterogeneously among elderly people, whereas second degree characteristics are caused by normal aging without any difference between the C and L segments.

Glucocorticoids known to be such powerful agents that cell growth, differentiation and cell death are influenced in the brain of mammals throughout life. Despite this, relatively little toxicological information regarding prenatal exposure is available. The aim of this study was to determine the effect of prenatal hydrocortisone exposure on cell viability and cell morphology in chick embryonic neurons. Four different histological staining techniques namely, Hematoxylin and Eosin (H&E), Cresyl Fast Violet, Silver impregnation and a combination of Gold Chloride and Toluidine Blue were used to evaluate chick embryo neural tissue exposed to 0.137ƒÝM or 0.685ƒÝM hydrocortisone on day 3.75 (Carnegie stage 16) and day 5.5 (Carnegie stage 18) of development. Histological processing was optimized and neural tissue evaluated for any changes in neuron morphology and cell number. Specific ultrastructural changes to membraneous structures were evaluated by transmission electron microscopy (TEM). Fixation procedures that resulted in little to no disruption of these structures were optimized and used in studies evaluating the effect of hydrocortisone on neuron morphology. Primary chick embryonic neuronal cultures were prepared and increasing concentrations of hydrocortisone (26.3nM, 0.16ƒÝM, 0.63ƒÝM, 3.8ƒÝM, and 22.8ƒÝM) added. Fluorescence microscopy was applied to the in vitro hydrocortisone exposed primary neuronal cultures. A combination of fluorescein diacetate (FDA) and propidium iodide (PI) was used to evaluate the effect of hydrocortisone on cell viability, whereas dichlorodihydrofluorescein diacetate (DCH2FDA) was used to visualize reactive oxygen species (ROS) generation in neurons. Histological evaluation of the neural tissue of chick embryos exposed to 0.137ƒÝM and 0.685ƒÝM hydrocortisone showed reduced neuron density and morphological changes associated with cell death. Glutaraldehyde with added magnesium chloride (MgCl2) as stabilizing chemical and potassium permangenate were two fixatives that caused minimal disruption to neural tissue. These two fixating methods were applied to control neural tissue as well as tissues exposed to 0.137ƒÝM and 0.685ƒÝM hydrocortisone. When evaluated by TEM, the control tissue appeared to be intact with no displacement. Exposure of neurons to 0.137ƒÝM hydrocortisone appeared to have severe effects on the morphology of the mitochondria, endoplasmic reticulum (ER), nuclear and plasma membranes. More extensive damage was noted with 0.685ƒÝM hydrocortisone, leaving almost no cellular structure. Both concentrations of hydrocortisone indicated cell death associated with apoptosis and necrosis. In vitro studies using primary cultures of chick neurons indicated that hydrocortisone is non-toxic at low concentrations (26.3nM ¡V 3.8ƒÝM) with the percentage viability ranging between 73% and 88%. A more toxic effect was seen at high concentrations (22.8ƒÝM). Cell death at the higher concentrations (22.8ƒÝM and 3.8ƒÝM) of hydrocortisone occurred due to ROS generation, as indicated by DCH2FDA fluorescence In conclusion, hydrocortisone indicated neurotoxicity at high concentrations of exposure. Although cell death could be detected, the exact mechanism (apoptosis or necrosis) still needs to be investigated. Since the developing brain is so susceptible to chemical insults care should be taken when administering this drug to pregnant mothers or young children. / Dissertation (MSc (Cell Biology)))--University of Pretoria, 2007. / Anatomy / unrestricted

Phlebotomine sandflies are blood sucking Dipteran and important vectors of various patogens, especially leishmania parasites (Trypanosomatida, Leishmaniinae). Apart from the genus Leishmania they also transmit variety of other parasites and they are considered to be vectors of trypanosomes (genus Trypanosoma) and hosts of some monoxenous trypanosomatids. This Master thesis is focused on the occurrence and development of mono- and dixenous trypanosomatids (other than the genus Leishmania) in sandflies. We studied experimental infections of various species of sandflies and mosquitoes by two species of trypanosomes and one species of monoxenous parasite (Strigomonas galati). All three studied trypanosomatid species were isolated from sandflies. Further concern of the thesis is the transmission of both species of trypanosomes from sandflies to vertebrate hosts and the transmission of monoxenous parasite between insect hosts and also morphological changes of parasite cells during the development in a culture and in the insect and vertebrate hosts.

The use of Computerised microtomography (CμT) in biomedical research is well established, with most applications developed at synchrotron facilities. The possibility to non-invasively monitor morphological changes in biological samples, makes it an attractive technique in biomedicine. However, high absorbed doses and long examination times are a disadvantage that limits the possibilities of performing longitudinal examinations. The aim of this work was to optimise CmT using conventional X-ray tubes for applications in non-destructive material testing and for skeleton research in small animals (rat). A calculational model of the imaging system was developed and used to optimise the relation between image quality, expressed as the signal-to-noise ratio (SNR) in detecting a contrasting detail, and imaging time in material testing. The model was modified to optimise the relation between the SNR in detecting a trabecular detail in cancelleous bone and the mean absorbed dose in spongiosa and skin for (rat) tibia and femur. Gastrectomized Sprague-Dawley rats were used to initiate osteoporotic changes. In order to detect differences in between gastrectomized rats and controls, spatial resolutions of 150 mm or better were needed. The minimum absorbed doses in femur spongiosa at SNR = 5 were 1mGy - 700 mGy at spatial resolutions from 100 mm to10 mm. In femur skin, the corresponding minimum absorbed doses were 2 mGy - 2000 mGy. Corresponding values for tibia were 0.3 mGy - 300 mGy for both spongiosa and skin (spatial resolution of 100 mm to10 mm). Taking 0.5 Gy as the tolerance limit for the spongiosa dose, longitudinal studies with six repeated examinations will be possible at a spatial resolution of 25 mm in femur and 17 examinations in tibia.

Dans ce travail de thèse, nous nous sommes intéressés à la simulation de l’évolution de la microstructure d’un polymère. Plus précisément, nous avons étudié le changement de la morphologie du polyéthylène téréphthalate (PET) sous l’effet de différents mécanismes. Ces simulations sont réalisées par la méthode des champs de phase. Il s’agit d’une méthode basée sur l’équation de Cahn-Hilliard ou l’équation de Ginzburg-Landau. Elle utilise un paramètre d’ordre pour décrire l’état du matériau, des variables thermodynamiques et cinématiques. Ainsi on peut décrire l’évolution d’une microstructure sans suivre l’interface et ainsi reproduire l’évolution de la structure cristalline sphérolitique qui apparait lors d’une cristallisation induite par la température. Dans le cadre d’un changement de morphologie induit par la température, le calcul par champ de phase a été simulé par la méthode de différences finies et la méthode d’éléments finis. Le coefficient cinétique a été identifié à partir de données expérimentales de la littérature. En introduisant un modèle du champ de phases multiples (the MPF model) on a aussi simulé l’évolution de plusieurs sphérolites et gérer la jonction lorsque deux sphérolites se rencontrent. La croissance et la jonction des sphérolite a été modélisée par la méthode d’éléments finis : elle reproduit parfaitement l’évolution expérimentale de cristallisation isotherme d’un polymère. En comparant ces résultats avec le modèle macroscopique d’Avrami, une évaluation de la constante d'Avrami, K(T), a été discutée en fonction des fluctuations des conditions initiales (positions et taille des germes).Dans le cadre de la cristallisation induite par la déformation mécanique, nous avons couplé le champ de phase aux équations de la mécanique pour un comportement viscoélastique différent pour chaque phase. L’influence, sur la cristallisation et l’orientation, de la déformation, de la vitesse de sollicitation, du contraste entre les phases sont étudiées et comparées qualitativement aux observations expérimentales. Il s’agit d’une étude préliminaire qui devra être poursuivie et affinée afin de prédire une morphologie plus réaliste / In this thesis work, we are interested in simulating the evolution of the microstructure of a polymer. In particular, we have studied in the morphology change of polyethylene terephthalate (PET) under different mechanisms. These simulations carried out by the phase field simulation. This method based on the Cahn-Hilliard equation or the Ginzburg-Landau equation. It uses an order parameter to describe the state of material, thermodynamic and kinetic variables. Thus we can describe the microstructure evolution without tracking the interface (which would require complex remeshing) and reproduce the evolution of the crystalline structure within the polymers, for example the growth of spherulites which appear during crystallization induced by temperature. Within the scope the morphology changing by the temperature, the evolution of phase field simulation is performed by the finite difference method and the finite element method. The kinetic coefficient is adjusted in order to fit the experiment data in of the literature. We introduce the multiphase field model (the MPF model) in order to simulate the evolution of several spherulites and to describe the junction of spherulites. The growth and junction of spherulites have been modeled by the finite element method and nicely reproduced in comparing the experimental evolution of isothermal crystallization of a polymer. Comparing these results with the Avrami macroscopic model, an evaluation of the Avrami constant, K (T), was discussed according to the fluctuations of the initial conditions (positions and size of the germs).In the following part, we study the crystallization induced by mechanical deformation. We are interested in the viscoelastic model to simulate the induced crystallization of PET in plane stress. The phase field model coupled to mechanics will be presented. Different viscoelastic behaviors have been considered for each phase. The influence on crystallization and orientation of the deformation, the stress velocity and the contrast between the phases are studied and compared qualitatively with the experimental observations. This is a preliminary study that will have to be continued in order to predict a more realistic morphology

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