Introduction: Subjects with insulin resistance (IR) and diabetes are at increased risk of cardiovascular disease (CVD) than those without diabetes, however the mechanistic basis remains elusive. Despite LDL-cholesterol lowering by statin therapy, two-thirds of all CVD events remain, constituting a significant 'residual risk' for CVD. This ‘residual risk’ has been found to be greater for patients with diabetes than those without diabetes. This suggests the role for alternative sources of lipoprotein-derived cholesterol in CVD during diabetes. Both type-1 diabetic as well as IR subjects have been found to have increased plasma concentrations of fasting intestinal derived apoB48 containing remnants (CM-r). However it is not known if the diabetic metabolic milieu indeed increases the susceptibility of the arteries to CM-r and if these indeed bind to arterial proteoglycans (PGs). Objectives: To determine arterial retention of CM-r in type-1 diabetes and IR using ex vivo perfusion methodology in a streptozotocin rat model of type 1 diabetes and JCR-LA-cp rat model of IR. To determine the direct binding affinity and capacity of CM-r to biglycan using an in vitro approach. Methods and Results: We observed increased arterial CM-R retention in type 1 diabetic vessels as well as in IR vessels when compared to control vessels. The retained CM-r colocalized with arterial biglycan in type 1 diabetic vessels and a direct correlation was observed between the CM-r and the presence of glycated proteins in type I diabetic arteries. The increased arterial CM-r retention in the IR rats was associated with increased arterial biglycan protein content. We have conclusively demonstrated for the first time that CM-r indeed bind to human biglycan. Conclusion: Tight glycemic control in patients with type 1 diabetes can alleviate CVD by reducing hyperglycemia and subsequent retention of CM-r. A significant increase in biglycan protein core content during IR is suggestive of early vascular remodeling and may help to explain how CM-r accumulate more readily during diabetes induced CVD. Based on the results from this study, individuals with IR may be at increased risk for atherogenesis due to increased atherogenicity of the post-prandial CM-r when compared to normal population. / Nutrition and Metabolism

No description available.

Supernova explosions are among the most energetic events known in the universe, leaving supernova remnants (SNRs) as their relics. The cores of massive stars collapse to form neutron stars, among the most compact and strongest magnets in the cosmos. The thesis studies a sample of such magnetic "beauties" in X-rays, the magnetars and high-magnetic field pulsars (HBPs), with the motivation to understand their evolutionary links. We also address the connection between these sources by investigating their environs through their securely associated SNRs. Magnetars have ultra-high magnetic fields B ~ 10^{14} - 10^{15} Gauss (G) and include the soft-gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). The HBPs have magnetic fields B ~ 10^{13} - 10^{14} G, intermediate between the classical rotation-powered pulsars (B ~ 10^{12} G) and magnetars. We focussed on two HBPs: J1119-6127 and J1846-0258, with similar spin-properties and associated with the SNRs G292.2-0.5 and Kes 75, respectively. In our studies, magnetar-like behavior was discovered from the Crab-like pulsar J1846-0258, clearly establishing a connection between the HBPs and magnetars for the first time, while no such behavior has been observed from PSR J1119-6127 so far. J1119-6127's overall X-ray properties together with its compact pulsar wind nebula resemble more the classical rotation-powered pulsars. We studied two magnetars, one from each sub-class: SGR 0501+4516 and AXP 1E 1841-045. The spectral and statistical analysis of the bursts and the persistent X-ray emission properties observed from them were found consistent with the magnetar model predictions as well as those seen in other SGRs. Finally, we probed the environment of these stellar magnets by performing a detailed X-ray imaging and spatially resolved spectroscopic study of two SNRs: G292.2-0.5 and Kes 73 associated with J1119-6127 and 1E 1841-045, respectively. We found that both SNRs point to very massive progenitors (>~25 solar masses), further supporting the growing evidence for magnetars originating from massive progenitors using other multiwavelength studies.

Supernova explosions are among the most energetic events known in the universe, leaving supernova remnants (SNRs) as their relics. The cores of massive stars collapse to form neutron stars, among the most compact and strongest magnets in the cosmos. The thesis studies a sample of such magnetic "beauties" in X-rays, the magnetars and high-magnetic field pulsars (HBPs), with the motivation to understand their evolutionary links. We also address the connection between these sources by investigating their environs through their securely associated SNRs. Magnetars have ultra-high magnetic fields B ~ 10^{14} - 10^{15} Gauss (G) and include the soft-gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). The HBPs have magnetic fields B ~ 10^{13} - 10^{14} G, intermediate between the classical rotation-powered pulsars (B ~ 10^{12} G) and magnetars. We focussed on two HBPs: J1119-6127 and J1846-0258, with similar spin-properties and associated with the SNRs G292.2-0.5 and Kes 75, respectively. In our studies, magnetar-like behavior was discovered from the Crab-like pulsar J1846-0258, clearly establishing a connection between the HBPs and magnetars for the first time, while no such behavior has been observed from PSR J1119-6127 so far. J1119-6127's overall X-ray properties together with its compact pulsar wind nebula resemble more the classical rotation-powered pulsars. We studied two magnetars, one from each sub-class: SGR 0501+4516 and AXP 1E 1841-045. The spectral and statistical analysis of the bursts and the persistent X-ray emission properties observed from them were found consistent with the magnetar model predictions as well as those seen in other SGRs. Finally, we probed the environment of these stellar magnets by performing a detailed X-ray imaging and spatially resolved spectroscopic study of two SNRs: G292.2-0.5 and Kes 73 associated with J1119-6127 and 1E 1841-045, respectively. We found that both SNRs point to very massive progenitors (>~25 solar masses), further supporting the growing evidence for magnetars originating from massive progenitors using other multiwavelength studies.

A sample of 9 small-diameter radio sources has been selected from the Molonglo Galactic Plane Survey (MGPS) and observed with the Australia Telescope Compact Array (ATCA) in the radio recombination line (RRL) at 5 GHz, in a search for young Galactic SNRs. Since the RRL emission is an unambiguous indicator of a thermal source, this method has been used to eliminate HII regions from the selected sample. In addition, the IRAS and MSX infrared data and spectral index measurements have been combined with the RRL studies to distinguish thermal and non-thermal sources in the selected sample. One source (G282.8-1.2) is identified here as a possible new young Galactic supernova remnant, based on its relatively weak infrared emission, steep radio spectrum and possible x-ray emission. However, the ATCA data are inconclusive and further studies are needed to confirm this result. Radio recombination line emission (H107 alpha) has been detected in 3 of the selected sources, eliminating them from the sample of SNR candidates. In addition, the parameters of the RRL emission from the identified HII regions have been used to estimate their properties. The RRL data are inconclusive for the remaining low brightness, extended sources in the sample. However, some of these sources are likely to be thermal HII regions according to the infrared and spectral index data. The selected method for distinguishing thermal and non-thermal Galactic radio sources seems promising. The selected ATCA configuration was appropriate for imaging relatively bright, compact sources, but a slightly modified observing technique is needed to successfully image low surface brightness, extended sources.

Thesis (Ph. D.)--University of Chicago, Dept. of Astronomy and Astrophysics, August 1997. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.) - University of Buenos Aires, 2005. / PDF copy of thesis. Includes bibliographic references.

We present a comprehensive study of interstellar X-ray extinction using the extensive Chandra supernova remnant (SNR) archive and use our results to refine the empirical relation between the hydrogen column density and optical extinction. In our analysis, we make use of the large, uniform data sample to assess various systematic uncertainties in the measurement of the interstellar X-ray absorption. Specifically, we address systematic uncertainties that originate from (i) the emission models used to fit SNR spectra; (ii) the spatial variations within individual remnants; (iii) the physical conditions of the remnant such as composition, temperature, and non-equilibrium regions; and (iv) the model used for the absorption of X-rays in the interstellar medium. Using a Bayesian framework to quantify these systematic uncertainties, and combining the resulting hydrogen column density measurements with the measurements of optical extinction toward the same remnants, we find the empirical relation N-H = (2.87 +/- 0.12) x 10(21) A(V) cm(-2), which is significantly higher than the previous measurements.

A porção paulista do Vale do Ribeira concentra a maior quantidade de comunidades remanescentes de quilombos do estado de São Paulo, abrangendo uma área de cerca de 10% de seu território. Por meio das análises de marcadores moleculares, de frequências de casais com mesmo sobrenome e de dados genealógicos, procuramos obter parâmetros globais de caracterização das comunidades: sistema de cruzamentos e medidas de subestruturação populacional. Utilizamos dados genealógicos de cerca de 2000 indivíduos e moleculares de cerca de 1000 indivíduos das comunidades de Maria Rosa, Pilões, Galvão, São Pedro, Pedro Cubas, Ivaporanduva, Sapatu, André Lopes, Nhunguara, Abobral (margens esquerda e direita), Poça e Reginaldo. A estimativa média de F obtida pela análise de genealogias apresentou valor 0,00134, o qual, embora subestimado devido à falta de informações genealógicas, é cerca de 1,5 vezes mais elevado do que a estimativa apresentada para a população total brasileira e duas vezes maior que a obtida para o estado de São Paulo, comparando-se a valores apresentados em outros isolados da literatura. A partir das análises de locos genômicos obtivemos, para as comunidades separadamente, os valores médios de F relativos aos 239 locos de todas as comunidades, dentre os quais 12 (5%) mostraram-se estatisticamente diferentes de zero ao nível de P <= 0,05/n, frequência esperada de desvios ocorrendo ao acaso. Quando analisada de forma conjunta, a população apresentou quatro dos 30 locos (13,33%) com desvios significativos de pan-mixia, valor acima do esperado ao acaso, o que indica um excesso de homozigose no isolado total. Obtivemos o valor médio total de F pela ponderação dos F de cada um dos locos pelos recíprocos de suas variâncias, estas calculadas por meio de uma metodologia inédita proposta neste trabalho, a qual é aplicável a casos de marcadores contendo mais de dois alelos. O valor médio de F que obtivemos é comparável aos obtidos de outros isolados da literatura. Os valores do índice Fst obtidos em uma análise de subestruturação populacional tiveram valores modestos geralmente bem menores que 5%, indicando a presença de níveis de subestruturação muito modestos. / Vale do Ribeira is a region located at the southern part of the state of São Paulo, corresponding to about 10% of its territory. Most of the quilombo remnants of the state are placed inside this region. Using both molecular markers and genealogical data analyses, we estimated population genetic parameters from the communities (breeding system and subestructure organization). Genealogical and molecular data (collected from 2000 and 1000 individuals respectively) were obtained from 13 quilombo communities: Maria Rosa, Pilões, Galvão, São Pedro, Pedro Cubas, Ivaporanduva, Sapatu, André Lopes, Nhunguara, Abobral (both left and right edges), Poça e Reginaldo. Genealogical analysis enabled us to obtain a mean F value of 0.00134, that represents an underestimate of the true value due to lack of reliable genealogical information. Even so, this value is almost 1.5 times higher than the value estimated for the total Brazilian population and almost twice as high than the same parameter estimated for the state of São Paulo. By means of genomic loci data analysis, we obtained mean nF/n value for the quilombo communities separately. Twelve (5%) out of a total of 239 loci from eight communities were in p2:2pq:q2 ratios, as expected by chance; and for the set of all quilombo communities, four (13.33%) out of 30 loci deviated significantly from Hardy-Weinberg ratios, indicating an excess of homozygosis. We also estimated the weighted mean value of F for the whole population by averaging the nF/n values obtained from each locus by the reciprocal of their corresponding variances. For calculating the variance of estimated nF/n values we developed a novel method that can be easily generalized to the case of any number of alleles segregating at an autosomal locus/ No significant levels of population subtructure were detected since the estimated Fst values among populations were in general quite modest. We present also, as attachment to this work, the listings of the main computer program codes we used in our calculations and a section on the evolution of the fixation index F under different systems of regular endogamy.

This thesis examines three core-collapse supernova remnants (SNR) - the Cygnus Loop in the Milky Way and 0453-68.5 and 0540-69.3 in the Large Magellanic Cloud - of varying ages and in varying states of interaction with the surrounding interstellar medium (ISM), using X-ray imaging spectroscopy with Chandra and supplemental data from other wavelengths. We use results from our analysis to address three main questions. First, we examine the applicability of the common Sedov-Taylor adiabatic blast wave model to core-collapse supernovae. Second, we determine the elemental abundances around the shell of these supernova remnants to determine if the use of SNRs as a gauge of abundances in the ISM is justified. Finally, we examine the pulsar wind nebulae (PWNe) in 0453-68.5 and 0540-69.3 and search for evidence of interaction between these PWNe and their immediate surroundings. We see highly inhomogeneous ISM surrounding all three surveyed SNRs, contrary to the key assumption in the Sedov-Taylor model of a uniform surrounding medium. In all three studied SNRs, we find that shock speeds are dependent on the density of the surrounding material. As subsidiary results, we also find depleted elemental abundances of oxygen, magnesium, and silicon, relative to typical ISM, around all three studied supernova remnants. Although this subsidiary result is not conclusive, we believe that it merits a followup study. In 0540-69.3 and 0453-68.5, which contain central pulsars, we find that the explosion directionality, which can be inferred from the pulsar's proper motion relative to the SNR, is not related to the morphology of the SNR itself. We conclude from this that the asymmetric shapes common in core-collapse supernova remnants can be more a function of the complex environments surrounding the progenitors of core- collapse supernovae than of the supernova explosions themselves. Finally, we see that the PWN in 0453-68.5 shows signs of having mixed with the surrounding thermal- emitting material, while the PWN in 0540-69.3 appears to have not mixed with or interacted with the surrounding SNR material to any substantial degree. We believe that this result may indicate that the degree of interaction between a PWN and its surroundings is dependent on age and possibly shell morphology, although further study is needed.