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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Global and local controls upon the deposition of organic-rich Cretaceous sequences of western Venezuela : a geochemical study

Perez-Infante, Julio Vicente January 1996 (has links)
No description available.
12

An evaluation of biochemical and molecular techniques for monitoring microbial survival and persistence in soils

Macnaughton, Sarah January 1992 (has links)
No description available.
13

Aeolian Delivery of Organic Matter to a Middle Permian Deepwater Ramp

Artan, Sinem 2011 May 1900 (has links)
Windblown dust is a significant source of sediment and organic matter for many basins, but its influence on ancient basins can be difficult to detect and quantify. We quantified the biomarker content, including n-alkanes, hopanes, and steranes of the Brushy Canyon Formation sandstones and siltstones to evaluate the significance of windblown dust in delivery of sediment and terrestrial organic matter to the Middle Permian Delaware Basin. Ramp siltstones of the basin have been interpreted as representing deposits of unconfined low-density turbidity currents or "aeolo-marine" sediments. We analyzed the organic contents of five samples of channel-confined turbiditic sandstones and siltstones and five samples of ramp siltstones outcropping in the Guadalupe Mountains National Park, West Texas, to estimate the relative proportions of terrestrial and marine organic matter in the two types of host rocks. The total organic carbon content of all samples varied from 0.07 percent - 2.04 percent. The abundance of high molecular weight n-alkanes (n-C27 and greater) suggests that terrestrial organic matter was present in nearly all samples. Terrestrial organic matter input to the basin was characterized using a crossplot of pristane/n-C17 versus phytane/n-C18. Ramp siltstones showed ~10-fold greater variation in terrestrial content than did turbiditic sandstones and siltstones. This observation is more consistent with the aeolo-marine interpretation of ramp siltstones, and suggests that terrestrial organic matter was delivered to the Delaware Basin by wind transport during deposition of the Brushy Canyon Formation.
14

A cross-sectional, correlational survey to explore the relationship between Renal Association biochemical and haematological markers and health-related quality of life in patients receiving haemodialysis in the North West of England

Winterbottom, Jean January 2015 (has links)
Introduction with Hypothesis/Objective: Management of long-term conditions requires a holistic approach, which places equal emphasis on the biomedical and the psychosocial. In chronic kidney disease (CKD), whilst biochemical and haematological parameters are routinely measured in accordance with UK Renal Association Standards and Guidelines this is not the case for health-related quality of life (HRQoL).There is evidence that achieving Renal Association biochemical/haematological targets improves mortality & morbidity. However, little evidence is available on whether achieving these targets enhances health-related quality of life (HRQoL). This study’s primary aim was, therefore, to determine whether there was any association between the extent to which patients achieved Renal Association biochemical and haematological targets and their HRQoL. A secondary aim was to explore the association between demographic and other treatment-related factors and HRQoL.Methods: A cross-sectional postal survey was conducted, involving 301 adult maintenance haemodialysis patients (age 18 + yrs.) in North-west England. HRQoL data were collected using the KDQoL-SF and patient records were searched for demographic variables and key biochemical/haematological markers derived from the UK Renal Association Standards and Guidelines. Biomarker achievement was categorised as ‘low achievers’ (patients who reached 0 – 2 Renal Association targets), ’medium achievers’ (3 – 5 targets) and ‘high achievers’ (6 – 8 targets). Data were initially analysed descriptively then using univariate and multivariate (multiple regression) analysis. Results: Participants were older (mean age 63.4 years), mostly male (64.0%) and predominantly white (87.0%); they had been on HD for a mean of 42.0 months (median 28.0). Patients typically had low scores for most aspects of HRQoL. For Renal Association targets, 5.6 % of the sample were ‘low achievers’, 57.1% ‘medium achievers’ and 35.2% ‘high achievers’. Apart from the KDQoL-SF subscale of symptom/problem list (medium achievers p<0.012, high achievers p<0.009), there was no association between HRQoL and the level of RA biomarkers achieved. Being Asian was negatively associated with several KDQoL-SF subscales. Increased age was positively associated with many subscales, suggesting a better toleration of poor health in older patients. The individual biomarker albumin was negatively associated with a number of the KDQoL subscales. Conclusion: The study’s findings demonstrate little association between achievement of Renal Association biochemical/haematological targets and HRQoL. A more holistic approach is required to address other aspects of physical and psychological health. Guidelines are needed that contain recommendations for routine monitoring of HRQoL scores. There is a need for better recognition of HRQoL as a specific treatment goal.
15

Identification of potential biomarkers for the detection of aggressive prostate cancer

Whiteland, Helen Louise January 2012 (has links)
No description available.
16

Eco-physiologie des réponses aux stress chimiques chez le poisson en milieu naturel : cas des salmonidés des îles Kerguelen

Jaffal, Ali 14 January 2011 (has links)
Les îles Kerguelen (40°S, 70°E) renferment des écosystèmes d’eau douce parmi les plus isolés du monde des activités anthropiques directes. Le but de ce travail était d’étudier les facteurs bio-écologiques influençant les niveaux de bioaccumulation des contaminants chimiques dans les tissus des salmonidés des îles Kerguelen (truite commune, Salmo trutta et omble de fontaine, Salvelinus fontinalis) et les effets toxiques potentiellement associés. Nos travaux ont permis de démontrer que les teneurs hépatiques et musculaires en Cd et en Cu, mais aussi les teneurs musculaires en PCB étaient élevées et comparables à celles détectées chez des populations de salmonidés de zones géographiques plus anthropisées. Par ailleurs, des différences de contamination selon l’espèce, la saison et le morphotype (lac, rivière et base) ont été mises en évidence. L’analyse histologique des foies des truites a mis en évidence des atteintes hépatiques (fibrose, infiltration des cellules immunitaires, développement de centres mélanomacrophagiques) et hepatocytaires (nécrose, altérations nucléaires) nettes de l’ensemble des poissons étudiés qui révelent un état de stress important en cohérence avec les forts taux de toxiques dans cet organe. D’autre part, les biomarqueurs des défenses anti-oxydantes ont mis en évidence des différences entre les morphotypes étudiés. Par ailleurs, l’analyse de l’activité sérique de lysozyme a montré que ces salmonidés sont caractérisés par des niveaux de compétences immunitaires réduits. Les îles Kerguelen constitue un site atelier pour les études écotoxicologiques. Le suivi sur le long terme, devrait améliorer la connaissance des variations des réponses écophysiologiques des populations de poissons d'eau douce face à la pression chimique globale. / The Kerguelen Islands (40°S, 70°E) contain freshwater ecosystems among the most isolated from human activities in the world. The aim of this work was to study the bio-ecological factors influencing levels of chemical bioaccumulation in Kergueln salmonids tissue (brown trout, Salmo trutta and brook trout, Salvelinus fontinalis) and their potential toxic effects. Our work demonstrated that the hepatic and muscular Cu and Cd levels, and also, the muscular PCB levels were hight and similar to those of salmonids from impacted areas. Moreover, differences in contamination according to species, season and morphotype (lake, river and base) were noted. Histological analysis of trouts livers showed clear damage of liver (fibrosis, infiltration of immune cells, development centers mélanomacrophagiques) and of hepatocytes (necrosis, nuclear alteration) in all studied fish traducing an important level of stress consistently with the high concentration of toxicant in this organ. On the other hand, antioxidant defenses biomarkers revealed differences between the studied morphotypes. Moreover, analysis of serum lysozyme activity showed that these salmonids were characterized by reduced immune competences. Kerguelen Islands constitute a workshop site for ecotoxicological studies. The long-term monitoring should improve the knowledge of changes in eco-physiological responses of freshwater fish populations dealing with the global chemical pressure.
17

A bioinformatics meta-analysis of differentially expressed genes in colorectal cancer

Chan, Simon Kit 05 1900 (has links)
BACKGROUND: Elucidation of candidate colorectal cancer biomarkers often begins by comparing the expression profiles of cancerous and normal tissue by performing high throughput gene expression profiling. While many such studies have been performed, the resulting lists of differentially expressed genes tend to be inconsistent with each other, suggesting that there are some false positives and negatives. One logical solution to this problem is to determine the intersection of the lists of differentially expressed genes from independent studies. It is expected that genes that are biologically relevant to cancer tumorigenesis will be reported most often, while sporadically reported genes are due to the inherent biases and limitations of each of the profiling platforms used. However, the statistical significance of the observed intersection among many independent studies is usually not considered. PURPOSE: To address these issues, we developed a computational meta-analysis method that ranked differentially expressed genes based on the following criteria, which are presented in order of importance: the amount of intersection among studies, total tissue sample sizes, and average fold change in expression. We applied this meta-analysis method to 25 independent colorectal cancer profiling studies that compared cancer versus normal, adenoma versus normal, and cancer versus adenoma tissues. RESULTS: We observed that some genes were consistently reported as differentially expressed with a statistically significant frequency (P <.0001) in the cancer versus normal and adenoma versus normal comparisons, but not in the cancer versus adenoma comparison. We performed a review of some of the high ranking candidates and determined that some have previously been shown to have diagnostic and/or prognostic utility in colorectal cancer. More interestingly, the meta-analysis method also identified genes that had yet to be tested and validated as biomarkers. Thus, these candidates are currently being validated at the protein level on colorectal tissue microarrays. CONCLUSION: Our meta-analysis method identified genes that were consistently reported as differentially expressed. Besides identifying new biomarker candidates, our meta-analysis method also provides another filter to remove false positive genes from further consideration. In conclusion, the genes presented here will aid in the identification of highly sensitive and specific biomarkers in colorectal cancer. / Science, Faculty of / Graduate
18

Microparticles and malignant pleurisy / Microparticules et pleurésies malignes

Roca, Elisa 09 May 2017 (has links)
Des marqueurs pleuraux pouvant discriminer les pleurésies bénignes et malignes sont nécessaires. Parmi les possibles biomarqueurs, les microparticules (MPs) ont été décrites dans les compartiments biologiques humains ; mais peu de données existent sur leur existence dans le liquide pleural. Etant donné que les cellules tumorales produisent un grand nombre de MPs, nous avons fait l’hypothèse de la présence de MPs tumoraux (TMPs) dans les pleurésies et de leur implication dans la carcinogénèse.Donc, pour la première fois nous avons montré de nombreuses MPs pleurales produites par des cellules normales et malignes et nous avons caractérisé leur cellule d’origine.De plus, nous avons montré des TMPs pleurales exprimant l’antigène EpCAM : ce travail donne les bases pour l’utilisation de ce prometteur biomarqueur pour classifier les pleurésies. Nous avons décrit des cas cliniques de patients avec cytologie négative, mais positifs à la présence de MPs pleurales EpCAM+ : donc, les MPs EpCAM+ peuvent être un outil complémentaire à la cytologie, pour améliorer le diagnostic des MPEs. Ce travail ouvre aussi de nouvelles perspectives pour un monitorage mini-invasif et pour une médecine personnalisée avec une cible EpCAM.Etant donné que les TMPs ont de nombreuses activités, il est possible que les MPs EpCAM+ jouent un rôle majeur dans la carcinogenèse au niveau du microenvironnement pleural.Ces résultats donnent les bases pour la détection des TMPs par cytométrie en flux comme possibles biomarqueurs non-invasif pour la classification des épanchements pleuraux. / Pleural biomarkers which could discriminate benign and malignant pleural effusion are needed.Among candidate biomarkers, microparticles (MPs), have been reported in human body fluids, but little is known about their existence in pleural fluid. Because tumor cells produce high numbers of MPs, we hypothesized the presence of tumor-derived MPs (TMP) in pleuresy and their involvement in carcinogenesis.Therefore, for the first time, we report the presence of high amounts of MPs originating from normal and malignant cells in pleural fluids, and we characterizes their cellular origin. Moreover, we showed pleural TMPs expressing the EpCAM antigen from carcinoma patients : this work establishes the basis for using this promising biomarker to distinguish benign and MPE. We showed clinical cases of cancer patients, negative at cytology, but positive for pleural EpCAM+MPs : thus, EpCAM+MPs may be considered as a complementary tool with the cytology to classify pleurisies. This work also opens new directions about mini-invasive monitoring and personalized medicine targeting EpCAM. Since TMPs also carry various features and genetic signatures implicated in malignacy, it can be assumed that EpCAM+MPs could behave as relevant players of carcinogenesis in the pleural microenvironment. Although the sensitivity and specificity of a diagnosis by TMPs should be established in larger multicenter cohorts, this study establishes the basis for the detection of TMPs by flow cytometry as potential biomarkers for the classification of pleural effusions.
19

TINT Tumor Indicating Normal Tissue : new field of diagnostic biomarkers for prostate cancer

Adamo, Hanibal Hani January 2016 (has links)
Background: Prostate cancer is the most common cancer in Sweden. Due its highly variable behavior, multifocal nature, and insufficient diagnostic methods, prostate cancer is difficult to diagnose and prognosticate. Some patients have an aggressive lethal disease, but the majority of prostate cancer patients have slow-growing, non-lethal disease with long expected survival without treatment. Current diagnostic methods―serum levels of prostate-specific antigen (PSA) and histological grading of biopsied prostate tissue―often do not give the information required to be able to safely differentiate indolent tumors from potentially lethal ones. Many prostate cancers are difficult to detect by imaging, so tissue biopsy cannot be safely guided towards the tumor, and particularly not towards the most aggressive forms. To overcome this problem, multiple needle biopsies are taken from the organ, but biopsies are small and they sample less than 1% of the whole prostate. In this thesis, we explore the non-malignant prostate tissue adjacent to tumors, which is always sampled in biopsies, and we study adaptive changes in this tissue, which may provide new diagnostic and prognostic markers for prostate cancer. We have therefore proposed that this type of tissue should be termed TINT (Tumor Instructed/indicating Normal Tissue).  Methods: In our studies, we used orthotopic rat prostate cancer models with tumors of different aggressiveness. We also used clinical materials from patients diagnosed with prostate cancer at transurethral resection (1975‒1990); the majority of these men were followed with watchful waiting. Analyses were performed with whole-genome expression array, quantitative real-time PCR, immunohistochemistry, and western blotting.  Results: Using the animal model, we found that the presence of a tumor induces changes in gene expression in the surrounding tumor-bearing organ (TINT). The gene signature of TINT was linked to processes such as extracellular matrix organization, immune responses, and inflammation. We also showed that some of these adaptive TINT changes appear to be related to the aggressiveness and metastatic potential of the growing tumor, such as increases in macrophages, in mast cells, in vascular densities, and in vascular cell-proliferation. Some of these findings were confirmed by our observations in patient samples. We found that high staining of the extracellular matrix component hyaluronan in the stroma of the non-malignant prostate tissue was prognostic for short cancer-specific survival. We also found that an elevated proportion of C/EBP-beta positive epithelial cells in non-malignant (TINT) prostate tissue was associated with a good prognosis.  Conclusions: Using animal experiments and patient samples, we showed that the presence of prostate cancer induces changes in the tumor-bearing organ, alterations associated with tumor aggressiveness, and that grading of these changes in TINT can be used to predict outcome in prostate cancer patients.
20

Physiological and cellular level responses of Enteromorpha spp. to chemical and thermal stress

Lewis, Stella Anne January 1998 (has links)
The aims of this project were to investigate the cellular stress response (CSR) in Enteromorpha spp. and assess the potential of the Stress-70 protein (an indicator of the CSR) as a biomarker of pollutant exposure and acquired tolerance in Enteromorpha spp., compared with conventional physiological endpoints of toxicity. Cross-reactivity of a commercial Stress-70 antibody with E. intestinalis proteins was determined and used to develop an assay for Stress-70. Using this assay E. intestinalis was found to exhibit a typical heat shock response. Stress-70 proved to be a relatively insensitive biomarker of copper exposure and did not appear to be involved in copper tolerance, the genetic basis of which was investigated by growing E. intestinalis using a novel culturing technique. Although growth was variable, it provided a simple, consistent and sensitive measure of copper toxicity. The chlorophyll fluorescence parameter Fv/Fm was insensitive to copper exposure. Nutrient limitation enhanced copper toxicity and significantly impaired growth, Fv/Fm and Stress-70 production in E. intestinalis. In both copper ‘sensitive’ and ‘tolerant’ E. intestinalis, copper exposure did not affect the ability to raise a heat shock response. In ‘sensitive’ algae, copper and heat shock were additive stressors, with heat shock acting as a stronger inducer of Stress-70. Only heat shock affected 'tolerant' algae. Zinc was less toxic than copper but in contrast to copper studies, Stress-70 was a relatively sensitive indicator of zinc exposure, compared to Fv/Fm and growth. Studies of triazine herbicides revealed that on a molarity basis, Irgarol 1051 was more toxic to E. intestinalis than atrazine. Fv/Fm and growth were strongly affected by Irgarol exposure, but Stress-70 levels were unaltered by exposure to the herbicide. Fv/Fm and Stress-70 were poor in situ biomarkers of pollution, but another chlorophyll fluorescence parameter - complementary area - appeared to correlate with levels of organic pollution. Overall, Stress-70 was found not to be a useful biomarker of exposure to copper or triazines in E. intestinalis, or in situ pollution. However, the Stress-70 assay developed has a number of alternative applications and Enteromorpha spp. were deemed to be potentially useful in pollution monitoring with the selection of suitable biomarker responses.

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