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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.
471

Genetic analysis of longevity in specialized lines of rabbits

El Nagar, Ayman Gamal Fawzy 29 June 2015 (has links)
[EN] The global objective of the present thesis was to study the functional longevity defined as length of productive life (LPL) in five Spanish specialized lines of rabbit (A, V, H and LP). Chapter 3, aimed to check the genetic heterogeneity for longevity between the five lines estimating the additive variance and the corresponding effective heritabilities. As well as to test the genetic importance of time-dependent factors such as positive palpation order (OPP), physiological status (PS) and number of kits born alive (NBA) on the genetics of longevity. This point has been assessed using four different Cox proportional hazard models; the first one (Model 1) included all the previous factors in addition to the year-season effect, the inbreeding coefficient effect and finally the animal effect as random factor. The remaining three models were the same as Model 1 but excluding OPP (Model 2), or PS (Model 3), or NBA (Model 4). The complete data set comprised 15,670 does with records 35.6 % having censoring data, and the full pedigree file involved 19,405 animals. The heritability estimates for longevity in the five lines were low and ranged from 0.02±0.01 to 0.14±0.09, and consequently, it is not recommended to include this trait as selection criteria in rabbit breeding programs. Despite of the large variation of the heritability estimates, the corresponding HPD95% always overlapped and consequently the hypothesis of all lines having the same heritability cannot be discarded. Comparing the additive variance estimates of the four models, it was observed that by correcting for PS 51, 39, 38, 83 and 75% of the additive variance in lines A, V, H, LP and R, respectively, was removed. The risk of death or culling decreases as OPP advanced. Non-pregnant-non-lactating females are those under the higher risk. The does which had zero NBA had the highest risk, apart for this special figure (zero NBA) the risk decreased as NBA increased. Chapter 4 intended to estimate the genetic and environmental correlations between longevity and two prolificacy traits (number of kits born alive (NBA) and number of kits alive at weaning (NW)). Furthermore, to estimate the genetic and environmental correlations between longevity and the percentage of days that the doe spent in the different physiological statuses with respect to its entire productive life. The complete pedigree file comprised 19,405 animals. The datasets included records on 15,670 does which had 58,329 kindlings and 57,927 weanings. In general the genetic correlations between NBA and NW, and the hazard were low to very low, and the only line for which it can be said these genetic correlation to be different from zero was the LP line. Regarding the correlations between longevity and the percentage of days the doe spent in each physiological status, there were evidences of non-negligible genetic correlations between the two traits. Chapter 5 purposed to compare the five lines at their foundation and at fixed time periods during their selection programs. The first comparison was done at the origin of the lines, involving the complete data set, and using a genetic model (CM) including the additive values of the animals, so the effect of selection was considered. For the second comparison the same model as the first comparison was used, but excluding the additive effects from the model of analysis (IM), and involving only the data corresponding to each period, so the differences between the lines included the additive values of the animals. The lines V, H and LP showed at foundation a substantial superiority over line A. The line R had higher risk of death or culling with relevant differences when compared to V, H and LP lines. The maximum relative risks were observed between the lines LP and R (0.239), and between LP and A (0.317). For the comparisons at fixed times, the pattern of the differences between the A line and the others was similar to those observed at foundation. / [ES] El objetivo global de la presente tesis fue estudiar la longevidad funcional en cinco líneas españolas de conejos (A, V, H y LP), el carácter se definió como la longitud de la vida productiva. En el Capítulo 3, dirigido a comprobar la heterogeneidad genética de la longevidad entre las 5 líneas, se estimaron las varianzas aditivas y sus correspondientes heredabilidades efectivas. Y además se evaluó la importancia del orden de la palpación positiva (OPP), el estado fisiológico (PS) y el número de gazapos nacidos vivos (NBA) sobre el determinismo genético de la longevidad. Para ello se utilizaron 4 modelos de Cox de riesgos proporcionales; el primer modelo (Modelo 1) incluyó todos los factores anteriores, además del efecto del año-estación, el efecto de la consanguinidad y, finalmente, el valor aditivo de los animales como efecto aleatorio. Los otros tres modelos fueron igual que el Modelo 1 pero excluyendo OPP (Modelo 2), o PS (Modelo 3), o NBA (Modelo 4). Los datos de longevidad estaban referidos a 15,670 conejas y tuvieron una tasa de censura de 35.6%. La genealogía completa involucró a 19,405 animales. Las estimas de heredabilidad efectiva para la longevidad en las 5 líneas fueron bajas y variaron de 0.02±0.01 a 0.14±0.09. A pesar de la gran variación de las estimas puntuales de heredabilidad, los correspondientes intervalos HPD95% siempre se solaparon y por lo tanto la hipótesis de que todas las líneas tengan la misma heredabilidad no pudo descartase. Se observó que la exclusión de PS incrementó la varianza aditiva aproximadamente, en un 51, 39, 38, 83 y 75% en las líneas A, V, H, LP y R, respectivamente. El riesgo de muerte o eliminación disminuía a medida que avanzaba el OPP, observándose el riesgo más alto durante los primeros dos partos, partos en los que las conejas todavía están creciendo lo que sería un factor de riesgo importante. El nivel No-Gestante-No-Lactante de PS tuvo el mayor riesgo. Este nivel se interpreta como indicador de baja fertilidad y/o problemas de salud de la coneja. Las conejas que tenían cero NBA tuvieron el mayor riesgo de muerte o eliminación, aunque para el resto de niveles de NBA se apreció una disminución del riesgo a medida que aumenta la prolificidad. En el capítulo 4, se estimaron las correlaciones genéticas y ambientales entre la longevidad y dos caracteres de prolificidad [número de gazapos nacidos vivos (NBA) y el número de destetados (NW)]. El fichero de datos incluyó 58,329 partos y 57,927 destetes. También se estimaron las correlaciones entre longevidad y el porcentaje de días que la coneja pasó en los diferentes estados fisiológicos con respecto a la totalidad de su vida productiva. La única línea para la que se puede decir que la correlación genética entre NBA o NW y el riesgo fue significativamente diferente de cero fue la línea LP. Hubo evidencias de correlaciones genéticas no despreciables entre la longevidad y el porcentaje de días que la hembra pasó en cada estado fisiológico los dos caracteres. En el capítulo 5 se compararon las longevidades medias de las 5 líneas en su fundación y en períodos de tiempo determinados. La comparación de las líneas en el origen, utilizó todos los datos y un modelo genético (CM) que incluía los valores aditivos de los animales. Para la comparación en tiempos fijos se utilizó el mismo modelo, pero excluyendo los efectos aditivos del modelo de análisis (IM), utilizando sólo los datos correspondientes a cada período, por lo que las diferencias entre las líneas incluían los cambios debidos a la selección. Las líneas V, H y LP mostraron una superioridad sustancial sobre las líneas A y R. Los riesgos relativos máximos se observaron entre las líneas LP y R (0.239), y entre LP y A (0.317). Con respecto a las comparaciones en tiempos fijos, el patrón de las diferencias entre la línea de A y las otras líneas fue similar a los observados en la fundación. / [CA] L'objectiu global de la present tesi va ser estudiar la longevitat funcional en cinc línies espanyoles de conills (A, V, H i LP), el caràcter es va definir com la longitud de la vida productiva. Al Capítol 3, dirigit a comprovar l'heterogeneïtat genètica de la longevitat entre les 5 línies, es van estimar les variàncies additives i les seues corresponents heretabilitats efectives. A més a més, es va avaluar la importància de factors dependents del temps, com l'orde de la palpació positiva (OPP) , l'estat fisiològic (PS) i el nombre de llorigons nascuts vius (NBA) sobre el determinisme genètic de la longevitat. Per a això es van utilitzar 4 models de Cox de riscos proporcionals; el primer model (Model 1) va incloure tots els factors anteriorment assenyalats, a més de l'efecte de l'any-estació, l'efecte de la consanguinitat i, finalment, el valor additiu dels animals com a efecte aleatori. Els altres tres models van ser igual que el Model 1 però excloent l'OPP (Model 2) , o PS (Model 3) , o NBA (Model 4) . Les dades de longevitat estaven referides a 15,670 conilles i van tindre una taxa de censura de 35.6%. La genealogia completa va involucrar a 19,405 animals. Les estimes d'heretabilitat efectiva (Model 1) per a la longevitat en les 5 línies van ser baixes i van variar de 0.02±0.01 a 0.14±0.09. A pesar de la gran variació de les estimes puntuals d'heretabilitat, els corresponents intervals HPD95% sempre es van solapar i per tant la hipòtesi que totes les línies tinguen la mateixa heretabilitat no va poder descartar-se. Es va observar que l'exclusió de PS va incrementar la variància additiva, aproximadament, en un 51, 39, 38, 83 i 75% en les línies A, V, H, LP i R, respectivament. El risc de mort o eliminació disminuïa a mesura que avançava l'OPP, observant-se el risc més alt durant els primers dos parts, en què les conilles encara estan creixent el que seria un factor de risc important. El nivell No-Gestant-No-Lactant de PS va tindre el major risc en comparació amb els altres nivells. Les conilles que tenien zero NBA van tindre el major risc de mort o eliminació, encara que per a la resta de nivells de NBA es va apreciar una disminució del risc a mesura que augmentà la prolificitat. Al Capítol 4, es van estimar les correlacions genètiques i ambientals entre la longevitat i dos caràcters de prolificitat [nombre de llorigons nascuts vius (NBA) i el nombre de deslletats (NW)]. El fitxer de dades va incloure 58,329 parts i 57,927 deslletaments. L'única línia per a la que es pot dir que la correlació genètica entre NBA o NW i el risc va ser significativament diferent de zero va ser la línia LP. Evidències de correlacions genètiques no menyspreables entre longevitat i els percentatge de dies que la femella va passar en cada estat fisiològic. Al Capítol 5 es compararen les longevitats mitges de les 5 línies en la seua fundació i en períodes de temps determinats. Per a la comparació de les línies a l'origen, es van utilitzar totes les dades i un model genètic (CM) que incloïa els valors additius dels animals, per la qual cosa es va considerar l'efecte de la selecció a partir de la fundació. En la comparació en temps fixos se va utilitzar el mateix model que en l'anterior, però excloent els efectes additius del model d'anàlisi (IM), utilitzant només les dades corresponents a cada període, per la qual cosa les diferències entre les línies incloïen els canvis deguts a la selecció. Les línies V, H i LP van mostrar una superioritat substancial sobre les línies A i R. Els riscos relatius màxims es van observar entre les línies LP i R (0.239), i entre LP i A (0.317). Respecte a les comparacions en temps fixos, el patró de les diferències entre la línia de A i les altres línies va ser semblant als observats en la fundació. / El Nagar, AGF. (2015). Genetic analysis of longevity in specialized lines of rabbits [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52390
472

Explainable and sparse predictive models with applications in reproductive health and oncology

Zad, Zahra 20 September 2024 (has links)
This dissertation develops explainable and sparse predictive models applied to two main healthcare applications: reproductive health and oncology. Through the application of advanced machine learning techniques and survival analysis, we aim to enhance predictive accuracy and provide actionable insights in these critical areas. The thesis is structured into four distinct problems, each focusing on a particular research question. The first problem concerns the prediction of the probability of conception among couples actively trying to conceive. Using self-reported health data from a North American preconception cohort study, we analyzed factors such as sociodemographics, lifestyle, medical history, diet quality, and specific male partner characteristics. Machine learning algorithms were employed to predict the probability of conception demonstrating improved discrimination and potential clinical utility. The second problem explores the application of machine learning algorithms to electronic health record (EHR) data for identifying predictor variables associated with polycystic ovarian syndrome (PCOS) diagnosis. Employing gradient boosted trees and feed-forward multilayer perceptron classifiers, we developed a scoring system that improved the model's performance, providing a valuable tool for early detection and intervention. The third problem focuses on predicting the risk of miscarriage among female participants who conceived during the study period. Utilizing both static and survival analysis, including Cox proportional hazard models, we developed predictive models to assess miscarriage risk. The study revealed that most miscarriages were due to random genetic errors during early pregnancy, indicating that miscarriage is not easily predicted based on preconception sociodemographic and lifestyle characteristics. Finally, the fourth problem focuses on the development of predictive models for managing Chronic Myeloid Leukemia (CML) patients. We developed models to predict whether patients will achieve deep molecular response (DMR) at later treatment stages and maintaining this status up to 60 months post-treatment initiation. These models offer insights into treatment effectiveness and patient management, aiming to support clinical decision-making and improve long-term patient outcomes. By emphasizing the explainability of these models, this dissertation not only aims to provide accurate predictions but also to ensure that the results are interpretable and actionable for healthcare professionals. Overall, this thesis showcases the potential of predictive modeling to improve reproductive health and oncology-related outcomes. The development and validation of various models in these contexts underscore the value of machine learning algorithms in healthcare research, analysis of epidemiologic data, and prediction of critical health events. The findings have significant implications for enhancing patient care, informing clinical practices, and guiding healthcare policy decisions.
473

台灣股票市場散戶存活率之研究 / How and Why Individual Investors Quit?

陳明憲, Chen, Ming-Hsien Unknown Date (has links)
Who can survive longer and what factors could prolong the trading life of individual investors in the market? This is the questions we ask in the dissertation. Based on our knowledge, there is not any research about the issue of survival analysis on analyzing individual investors in stock market. The paper classifies three possibilities could affect the trading life of investors: personal characteristics, trading behavior, and market condition. In the dissertation, we use tick-by-tick transaction data from the Taiwan Stock Exchange to profile survivors versus non-survivors, to investigate how the traders’ characteristics (such as, gender), trading behaviors (such as the degree of diversification, trading amount and trading frequency) and market condition affect the trading life of investors. We borrow the proportional hazard models proposed by Cox (1972) who used in bio-statistics to analyze the survival rate. Using the Kaplan-Meier curves for male and female, we find that survival functions and hazard rates of female investors have better survival prognosis than the male investors. Different timing of entering results in distinct patterns of survival curves and hazard rates. Investors entering that market in the bull and bear market have a larger survival rate than those who enter the market in normal time during the trading life from 1 to 7 years. Moreover, as the trading life increases larger 7 year, the three curves of bull, bear and normal market conditions, respectively, appear to get closer, suggesting that if trading life is shorter than 7 years, the investors entering in the bull and bear markets seemly have lower hazard ratio than that in the normal market to leave the market. Finally, the results of Cox’s proportional hazard model show that female investors stay in the market 74 days longer than the male. Trading cycle increasing by one day will prolong the traders in the market by 4.8 days. Average volume per trade measured in ten thousands does not have economic effect on the trading duration, although its estimate is statistically significant. A one percentage increase of portfolio return will reduce about 151 days of the trading life. One more stock in the portfolio will prolong about 133 days in the trading life. The effect on the trading duration of trading performance of those who enter in the bull market is positive. / Who can survive longer and what factors could prolong the trading life of individual investors in the market? This is the questions we ask in the dissertation. Based on our knowledge, there is not any research about the issue of survival analysis on analyzing individual investors in stock market. The paper classifies three possibilities could affect the trading life of investors: personal characteristics, trading behavior, and market condition. In the dissertation, we use tick-by-tick transaction data from the Taiwan Stock Exchange to profile survivors versus non-survivors, to investigate how the traders’ characteristics (such as, gender), trading behaviors (such as the degree of diversification, trading amount and trading frequency) and market condition affect the trading life of investors. We borrow the proportional hazard models proposed by Cox (1972) who used in bio-statistics to analyze the survival rate. Using the Kaplan-Meier curves for male and female, we find that survival functions and hazard rates of female investors have better survival prognosis than the male investors. Different timing of entering results in distinct patterns of survival curves and hazard rates. Investors entering that market in the bull and bear market have a larger survival rate than those who enter the market in normal time during the trading life from 1 to 7 years. Moreover, as the trading life increases larger 7 year, the three curves of bull, bear and normal market conditions, respectively, appear to get closer, suggesting that if trading life is shorter than 7 years, the investors entering in the bull and bear markets seemly have lower hazard ratio than that in the normal market to leave the market. Finally, the results of Cox’s proportional hazard model show that female investors stay in the market 74 days longer than the male. Trading cycle increasing by one day will prolong the traders in the market by 4.8 days. Average volume per trade measured in ten thousands does not have economic effect on the trading duration, although its estimate is statistically significant. A one percentage increase of portfolio return will reduce about 151 days of the trading life. One more stock in the portfolio will prolong about 133 days in the trading life. The effect on the trading duration of trading performance of those who enter in the bull market is positive.
474

HOME-BASED REHABILITATION AND ITS IMPACT ON HOSPITAL UTILIZATION

Knott, T. CHRISTINE 27 June 2013 (has links)
There is compelling evidence for the effectiveness of home-based occupational therapy and physiotherapy rehabilitation for community dwelling elderly who may struggle with basic activities and the functions of daily living and mobility. Nonetheless, an estimated 2% of home care’s elderly clients receive these therapies. Ontario’s home care data indicates that 78% of clients that could benefit from these specific therapies are not receiving them. The study examined a subset of elderly clients receiving home care following a hospital discharge during 2009-2010. The aim of this study was to: understand the difference between those home care clients who received occupational therapy or physiotherapy and those who did not; and determine if receiving these therapies impacted the utilization of hospital emergency departments and inpatient admissions. A retrospective cohort design and multivariate and survival analysis of hospital and home care administrative data structured the study. Results suggest that home-based rehabilitation is offered to a minority of the home care population. Distinct client characteristics and process variables significantly associated with the increased likelihood of receiving home-based occupational and physical therapies included: clients who were older, females, admitted to home care from hospital inpatient units, assessed as non-acute for clinical and service needs and required more home making support and assistance with activities of daily living. Almost one quarter of the total sample returned to hospital. Visits to emergency departments accounted for the greater part of hospital utilization and primarily for sub-acute general symptoms and signs, post-procedural complications, infections or acute episodes from chronic obstructive pulmonary disease and renal failure. Slightly over half of the clients returning to hospital did not receive home-based rehabilitation. Clients who received occupational therapy returned to the hospital sooner following their home care admission whereas clients receiving physiotherapy spent the longest time before rehospitalizing. The majority of the clients receiving occupational therapy were admitted to home care having just resolved sub-acute conditions or symptoms, many of which are known to influence functional and physical decline. Moreover, analysis of process variables indicated that the wait time for a referral to occupational therapy was two times longer compared to physiotherapy. These same clients also waited, on average, over one month before an occupational therapist’s first visit. The need to discriminate who receives home-based rehabilitation is essential to understanding how specific therapies contribute to improving systems outcomes. This study is the first examination that focuses specifically on home-based occupational therapy and physiotherapy rehabilitation and the client characteristics and process variables associated with receiving/not receiving these therapies and the impact these factors have on the time-to-rehospitalization. / Thesis (Ph.D, Rehabilitation Science) -- Queen's University, 2013-06-27 12:24:53.085
475

Atrial fibrillation in cardiac surgery

Ahlsson, Anders January 2008 (has links)
Atrial fibrillation (AF) is the most common arrhythmia seen in clinical practice. In cardiac surgery, one-third of the patients experience episodes of AF during the first postoperative days (postoperative AF), and patients with preoperative AF (concomitant AF) can be offered ablation procedures in conjunction with surgery, in order to restore ordinary sinus rhythm (SR). The aim of this work was to study the relation between postoperative AF and inflammation; the long-term consequences of postoperative AF on mortality and late arrhythmia; and atrial function after concomitant surgical ablation for AF. In 524 open-heart surgery patients, C-reactive protein (CRP) serum concentrations were measured before and on the third day after surgery. There was no correlation between levels of CRP and the development of postoperative AF. All 1,419 patients with no history of AF, undergoing primary aortocoronary bypass surgery (CABG) in the years 1997–2000 were followed up after 8.0 years. The mortality rate was 191 deaths/1,000 patients (19.1%) in patients with no AF and 140 deaths/419 patients (33.4%) in patients with postoperative AF. Postoperative AF was an age-independent risk factor for late mortality, with a hazard ratio (HR) of 1.56 (95% CI 1.23–1.98). Postoperative AF patients had a more than doubled risk of death due to cerebral ischaemia, myocardial infarction, sudden death, and heart failure compared with patients without AF. All 571 consecutive patients undergoing primary CABG during the years 1999–2000 were followed-up after 6 years. Questionnaires were obtained from 91.6% of surviving patients and an electrocardiogram (ECG) from 88.3% of all patients. In postoperative AF patients, 14.1% had AF at follow-up, compared with 2.8% of patients with no AF at surgery (p<.001). An episode of postoperative AF was found to be an independent risk factor for development of late AF, with an adjusted risk ratio (RR) of 3.11 (95% CI 1.41–6.87). Epicardial microwave ablation was performed in 20 open-heart surgery patients with concomitant AF. Transthoracic echocardiography was performed preoperatively and at 6 months postoperatively. At 12 months postoperatively 14/19 patients (74%) were in SR with no anti-arrhythmic drugs. All patients in SR had preserved left and right atrial filling waves (A-waves) and Tissue velocity echocardiography (TVE) showed preserved atrial wall velocities and atrial strain. In conclusion, postoperative AF is an independent risk factor for late mortality and later development of AF. There is no correlation between the inflammatory marker CRP and postoperative AF. Epicardial microwave ablation of concomitant AF results in SR in the majority of patients and seems to preserve atrial mechanical function.
476

Prognostički faktori za preživljavanje kod gerijatrijskih bolesnika sa uznapredovalim stadijumom nemikrocelularnog karcinoma bronha / Prognostic factors for survival in geriatric patients with advanced stage of non-small cell lung cancer

Sazdanić-Velikić Danica 23 September 2016 (has links)
<p>UVOD: Savremenim dijagnostičkim i terapijskim dostignućima, kao i unapređenjem preventivnih mera produžen je životni vek ljudi. Starenje stanovni&scaron;tva je fenomen koji zahvata ceo svet. Povećanje broja starijeg stanovni&scaron;tva je udruženo sa porastom broja obolelih od karcinoma u ovoj starosnoj grupi, jer je starenje samo po sebi riziko faktor za nastanak karcinoma. Incidenca pojave karcinoma naglo raste od 50-te godine života sa vrhom u 80-toj godini života. U osoba starijih od 65 godina se dijagnostikuje 58% svih karcinoma, a 30% u starijih od 70 godina. Godine starosti nisu kontraindikaciija za sprovođenje hemioterapije kod starih bolesnika sa karcinomom. Starenje je povezano sa izmenjenom farmakodinamikom i farmakokinetikom antitumorskih lekova i povećanom osetljivo&scaron;ću normalnog tkiva na toksične komplikacije, te je odluka kliničara kod davanja hemioterapije ovoj starosnoj kategoriji bolesnika sa karcinomom uvek vrlo kompleksna i zahteva dobru procenu i odgovarajuću selekciju bolesnika za ovaj tretman. MATERIJAL I METODE: Doktorska disertacija obuhvata rezultate delom restrospektivnog, a delom prospektivnog opservacionog istraživanja sprovedenog u periodu 01.01.2011. do 31.12.2013.godine u Institutu za plućne bolesti Vojvodine u Sremskoj Kamenici, u kojem je praćeno 152 bolesnika starosti 65 i vi&scaron;e godina kod kojih je dijagnostikovan nemikrocelularni karcinom bronha u uznapredovalom stadijumu bolesti, a koji su lečeni kombinovanim hemioterapijskim režimom na bazi platine. Kao prognostički faktori su uzeti: starosna dob bolesnika (grupa mlađih od 75 godina i starih 75 i vi&scaron;e godina), pol, navika pu&scaron;enja cigareta (pu&scaron;ač, nepu&scaron;ač, biv&scaron;i pu&scaron;ač), navika konzumiranja alkohola, performans status (prema ECOG-Eastern Cooperative Oncology Group skali) u momentu postavljanja dijagnoze, patohistolo&scaron;ki tip tumora (adenokarcinom, skvamozni karcinom, drugo), stadijum bolesti (IIIb, IV), veličina tumora (manje od 6 cm i 6 cm i vi&scaron;e), TNM status prema klasifikaciji tumora (7.revizija), parametri krvne slike (vrednosti leukocita, hemoglobina, trombocita), biohemijski parametri (vrednosti laktat-dehidrogenaze (LDH), alkalne fosfataze, aspartat- aminotransferaze (AST), alanin-aminotransferaze (ALT), kalijuma, natrijuma, bilirubina) na početku terapije, komorbiditeti u momentu postavljanja dijagnoze (broj komorbiditeta po sistemima, Charlson index), simptomi bolesti (ka&scaron;alj, hemoptizije, otežano disanje, bol u grudnom ko&scaron;u, promuklost, smetnje gutanja, sindrom gornje &scaron;uplje vene, bol u kostima, simptomi od strane centralnog nervnog sistema, povi&scaron;ena telesna temperatura), gubitak na telesnoj masi (vi&scaron;e od 5% u prethodnih 6 meseci), indeks telesne mase (&lt;18,5kg/m&sup2; pothranjen, 18,5-24,9kg/m&sup2; normalno uhranjen, 25-29,9kg/m&sup2; prekomerna telesna masa, ˃30kg/m&sup2; gojaznost). Svi potencijalni prognostički faktori su evaluirani univarijantnom analizom, a potom su svi faktori rizika za koje je utvrđena značajnost analizirani primenom multivarijantne logističke regresije, u cilju prepoznavanja nezavisnih prediktora za dvogodi&scaron;nje preživljavanje. Za otkrivanje nezavisnih prediktora preživljavanja na dve godine je primenjena binarna logistička regresiona analiza, a kao potencijalni prediktori su bile sledeće varijable: starost ispod 75 godina, pu&scaron;ačka navika, patohistolo&scaron;ki tip karcinoma, stadijum bolesti IV, T4 status, M1b status, prisustvo respiratornog komorbiditeta, otežano disanje, bol u grudima. Kumulativno preživljavanje je prikazano Kaplan-Meier-ovim krivama. Primenom multivarijantne Cox- regresione analize su dobijeni nezavisni prediktori kumulativnog preživljavanja. Iz dobijenih prognostičkih faktora koji se izdvajaju kao nezavisni prediktori za preživljavanje su kreirani matematički modeli za dvogodi&scaron;nje preživljavanje. CILJ ISTRAŽIVANJA: Utvrditi uticaj pojedinih prognostičkih faktora na dvogodi&scaron;nje preživljavanje ovih bolesnika i iz toga izvesti matematički model za stratifikaciju ovih bolesnika u odnosu na dvogodi&scaron;nje preživljavanje. REZULTATI: Analizom prognostičkih faktora je utvrđeno da grupa bolesnika starih 75 godina i vi&scaron;e ima ne&scaron;to duže dvogodi&scaron;nje preživljavanje od grupe bolesnika mlađih od 75 godina, ali bez statističke značajnosti, bolesnici sa tumorom veličine 6 cm i vi&scaron;e imaju kraće dvogodi&scaron;nje preživljavanje u odnosu na bolesnike sa tumorom manjim od 6 cm, bolesnici kod kojih je u momentu postavljanja dijagnoze T status tumora bio T4, a M status M1b imaju kraće dvogodi&scaron;nje preživljavanje, bolesnici kod kojih je na početku tretmana u laboratorijskim nalazima bila prisutna anemija i povi&scaron;ene vrednosti LDH imaju kraće dvogodi&scaron;nje preživljavanje, prisustvo vi&scaron;e komorbiditeta utiče na kraće preživljavanje, bolesnici sa gubitkom na telesnoj masi većim od 5% u periodu 6 meseci pre postavljanja dijagnoze bolesti imaju kraće dvogodi&scaron;nje preživljavanje. Kreirana su dva matematička modela (jedan za preživljavanje na 2 godine i jedan za kumulativno preživljavanje) za stratifikaciju gerijatrijskih bolesnika sa uznapredovalim stadijumom nemikrocelularnog karcinoma bronha lečenih hemioterapijom na bazi platine u odnosu na dvogodi&scaron;nje preživljavanje. ZAKLJUČAK: Dobijeni matematički modeli za preživljavanje gerijatrijskih bolesnika sa uznapredovalim stadijumom nemikrocelularnog karcinoma bronha lečenih hemioterapijom na bazi platine na jednostavan način stratifikuju bolesnike u odnosu na preterapijske prognostičke faktore za razliku od sveobuhvatne gerijatrijske procene koja je vremenski zahtevna procedura i zahteva obučen kadar.</p> / <p>INTRODUCTION: Nowadays life expectancy is prolonged due to modern diagnostic and therapy achievements, as well as promotion of preventive measurements. Aging of population is a phenomenon in the whole world. Increasing number of elderly population is accompanied with the increased number of diagnosed cancer in this age group, because the aging themselves is a risk factor for development of cancer. The appearance of cancer rapidly rises from the age of fifty with the peak at the age of eighty. 58% of cancer diagnoses are in the people older than sixty-five years and 30% in people older than seventy years. The age is not contraindication for chemotherapy treatment in older patient with cancer. The aging is associated with disturbed pharmacodynamics and pharmacokinetics of antitumor drugs and increased susceptibility of normal tissue for toxic complications, therefore clinical decision for introducing chemotherapy is very complex and requires good assessment and proper selection of the patients for this treatment. MATERIAL AND METHODS: This doctoral thesis includes results of partly retrospective and partly prospective observational research conducted in the period 01.01.2011. until 31.12.2013. at the Institute for pulmonary diseases of Vojvodina in Sremska Kamenica, which includes 152 lung cancer patients 65 and more years old with diagnosed non-small cell lung cancer in advanced stage treated with combined platinum based chemotherapy regimen. These prognostic factors are included: age of patients (group &lt;75 years, group &ge;75 years old), sex, smoking cessation (smoker, former smoker, non smoker), alcohol consuming habit, performance status (according to the ECOG-Eastern Cooperative Oncology Group scale) in the moment of confirmed diagnosis, pathohistological type of tumor (adenocarcinoma, squamous cell carcinoma, other), stage of disease (IIIb, IV), tumor size (&lt;6cm and &ge;6cm), TNM status according tumor classification (7th revision), blood count parameters (leucocyte, hemoglobin level, thrombocyte), biochemical parameters (lactate-dehydrogenase level (LDH), alkaline phosphatase level, aspartate aminotransferase level (AST), alanine aminotransferase level (ALT), potassium level, sodium level, bilirubin level) on the start of the chemotherapy, comorbidities at the moment of diagnosis (number of comorbid conditions, Charlson index), symptoms of the disease (cough, hemoptysis, dyspnea, chest pain, hoarseness, swallowing difficulties, caval venae compression symptoms, bone pain, central nervous symptoms, increased body temperature), weight loss (˃ 5% in the previous 6 months), body mass index (&lt;18,5kg/m&sup2; underweight 18,5-24,9kg/m&sup2; normal weight, 25-29,9kg/m&sup2; overweight , ˃30kg/m&sup2; obese). All potential prognostic factors were evaluated with univariante analysis, and after that all factors with confirmed significance were analysed with multivariante logistic regression, in order to identify independent predictors for 2-year survival. Binary logistic regression analysis was applied for identifying independent predictors for 2-years survival and those variables were analysed : age &lt;75 years, smoking cessation, pathohistological type of cancer, stage of disease IV, T4 status, M1b status, presence of respiratory comorbidity, dyspnea, chest pain. Cumulative survival of those patients was shown with Kaplan-Meier prognostic curves. Two mathematical model for 2-year survival was created from the factors confirmed as independent predictors for survival. AIM: This research objectives were to determine the influence of certain prognostic factors on 2-years survival of those patients and to create mathematical model for stratification of those patients related to 2-years survival. RESULTS: Univariante analysis confirmed that the group of patients older than 75 years and more have had better 2-year survival than group of patient younger than 75 year, but without the statistically significance, patients with tumor size &ge;6cm have had worst 2-year survival in comparison with patients with tumor size &lt;6cm, patients with tumor status T4 at the moment of diagnosis and M status M1b have had the shorter 2-year survival, patients with anemia and increased LDH level on the start of the chemotherapy treatment have had shorter 2-year survival, the presence of more comorbid conditions at the moment of diagnosis influence on shorter 2-year survival, patients with weight loss more than 5% in the previous 6 months have had shorter 2-year survival. Two mathematical models were created (one for 2-year survival and the other for the cumulative survival) for stratification of elderly patients with advanced staged non-small cell lung cancer treated with combined platinum based chemotherapy regimen related to 2-year survival. CONSLUSION: Created mathematical models for stratification of elderly patients with advanced staged non-small cell lung cancer treated with combined platinum based chemotherapy regimen more easily stratify patients compared to pretreatment prognostic factors as opposed to comprehensive geriatric assessment which is time-consuming procedure and requires trained personnel.</p>
477

An integrated genomic approach for the identification and analysis of single nucleotide polymorphisms that affect cancer in humans

Repapi, Emmanouela January 2013 (has links)
The identification of genetic variants such as single nucleotide polymorphisms (SNPs), which affect cancer progression, survival and response to treatments could help in the design of better prevention and treatment strategies. Genome-wide association studies (GWAS) have provided the first step of identifying SNPs associating with cancer risk. However, identifying the causal SNPs responsible for the associations has proven challenging, and GWAS have not been successful for time-to-event phenotypes such as cancer progression, due to the insurmountable obstacle of the large sample size needed. The aim of this thesis is to design and implement strategies that combine the identification of SNPs significantly associated with cancer, focusing on time-to-event phenotypes, with detailed bioinformatics analysis to allow for further experimental validation and modelling, to better understand cancer-associated genomic loci and accelerate their incorporation into the clinic. First, a methodology that utilises the Random Survival Forest is developed and combined with a bioinformatics analysis that ranks SNPs according to their potential to result in differential protein levels or activity, in order to identify SNPs that affect the progression of B-cell chronic lymphocytic leukaemia. Next, an analysis that aims to extend our understanding of the role of SNPs in mediating the cellular responses to chemotherapeutic agents is applied. SNPs that could associate with differential cellular growth responses in cancer cell line panels are identified, and their association with the differential survival of cancer patients is explored. Finally, the potential roles of SNPs in affecting the transcriptional regulation of key cancer genes resulting in differential cancer risk are assessed. First, by focusing on SNPs in an important transcription factor binding motif that has been shown to be extremely sensitive to single base pair changes (the E-box) and next, by exploring the possibility that polymorphic transcription factor binding sites could underlie the significant associations noted in cancer GWAS.
478

STATISTICAL MODELS AND ANALYSIS OF GROWTH PROCESSES IN BIOLOGICAL TISSUE

Xia, Jun 15 December 2016 (has links)
The mechanisms that control growth processes in biology tissues have attracted continuous research interest despite their complexity. With the emergence of big data experimental approaches there is an urgent need to develop statistical and computational models to fit the experimental data and that can be used to make predictions to guide future research. In this work we apply statistical methods on growth process of different biological tissues, focusing on development of neuron dendrites and tumor cells. We first examine the neuron cell growth process, which has implications in neural tissue regenerations, by using a computational model with uniform branching probability and a maximum overall length constraint. One crucial outcome is that we can relate the parameter fits from our model to real data from our experimental collaborators, in order to examine the usefulness of our model under different biological conditions. Our methods can now directly compare branching probabilities of different experimental conditions and provide confidence intervals for these population-level measures. In addition, we have obtained analytical results that show that the underlying probability distribution for this process follows a geometrical progression increase at nearby distances and an approximately geometrical series decrease for far away regions, which can be used to estimate the spatial location of the maximum of the probability distribution. This result is important, since we would expect maximum number of dendrites in this region; this estimate is related to the probability of success for finding a neural target at that distance during a blind search. We then examined tumor growth processes which have similar evolutional evolution in the sense that they have an initial rapid growth that eventually becomes limited by the resource constraint. For the tumor cells evolution, we found an exponential growth model best describes the experimental data, based on the accuracy and robustness of models. Furthermore, we incorporated this growth rate model into logistic regression models that predict the growth rate of each patient with biomarkers; this formulation can be very useful for clinical trials. Overall, this study aimed to assess the molecular and clinic pathological determinants of breast cancer (BC) growth rate in vivo.
479

Validation des modèles statistiques tenant compte des variables dépendantes du temps en prévention primaire des maladies cérébrovasculaires

Kis, Loredana 07 1900 (has links)
L’intérêt principal de cette recherche porte sur la validation d’une méthode statistique en pharmaco-épidémiologie. Plus précisément, nous allons comparer les résultats d’une étude précédente réalisée avec un devis cas-témoins niché dans la cohorte utilisé pour tenir compte de l’exposition moyenne au traitement : – aux résultats obtenus dans un devis cohorte, en utilisant la variable exposition variant dans le temps, sans faire d’ajustement pour le temps passé depuis l’exposition ; – aux résultats obtenus en utilisant l’exposition cumulative pondérée par le passé récent ; – aux résultats obtenus selon la méthode bayésienne. Les covariables seront estimées par l’approche classique ainsi qu’en utilisant l’approche non paramétrique bayésienne. Pour la deuxième le moyennage bayésien des modèles sera utilisé pour modéliser l’incertitude face au choix des modèles. La technique utilisée dans l’approche bayésienne a été proposée en 1997 mais selon notre connaissance elle n’a pas été utilisée avec une variable dépendante du temps. Afin de modéliser l’effet cumulatif de l’exposition variant dans le temps, dans l’approche classique la fonction assignant les poids selon le passé récent sera estimée en utilisant des splines de régression. Afin de pouvoir comparer les résultats avec une étude précédemment réalisée, une cohorte de personnes ayant un diagnostique d’hypertension sera construite en utilisant les bases des données de la RAMQ et de Med-Echo. Le modèle de Cox incluant deux variables qui varient dans le temps sera utilisé. Les variables qui varient dans le temps considérées dans ce mémoire sont iv la variable dépendante (premier évènement cérébrovasculaire) et une des variables indépendantes, notamment l’exposition / The main interest of this research is the validation of a statistical method in pharmacoepidemiology. Specifically, we will compare the results of a previous study performed with a nested case-control which took into account the average exposure to treatment to : – results obtained in a cohort study, using the time-dependent exposure, with no adjustment for time since exposure ; – results obtained using the cumulative exposure weighted by the recent past ; – results obtained using the Bayesian model averaging. Covariates are estimated by the classical approach and by using a nonparametric Bayesian approach. In the later, the Bayesian model averaging will be used to model the uncertainty in the choice of models. To model the cumulative effect of exposure which varies over time, in the classical approach the function assigning weights according to recency will be estimated using regression splines. In order to compare the results with previous studies, a cohort of people diagnosed with hypertension will be constructed using the databases of the RAMQ and Med-Echo. The Cox model including two variables which vary in time will be used. The time-dependent variables considered in this paper are the dependent variable (first stroke event) and one of the independent variables, namely the exposure.
480

AN ASSOCIATION STUDY BETWEEN ADULT BLOOD PRESSURE AND TIME TO FIRST CARDIOVASCULAR DISEASE

Pu, Yongjia 01 January 2015 (has links)
BACKGROUND: Several studies have demonstrated the association between the time to hypertension event and multiple baseline measurements for adults, yet other survival cardiovascular disease (CVD) outcomes such as high cholesterol and heart attack have been somewhat less considered. The Fels Longitudinal Study (FLS) provides us an opportunity to connect adult blood pressure (BP) at certain ages to the time to first CVD outcomes. The availability of long-term serial BP measurements from FLS also potentially allows us to evaluate if the trend of the measured BP biomarkers over time predicts survival outcomes in adulthood through statistical modeling. METHODS: When the reference standard is right-censored time-to-event (survival) outcome, the C index or concordance C, is commonly used as a summary measure of discrimination between a survival outcome that is possibly right censored and a predictive-score variable, say, a measured biomarker or a composite-score output from a statistical model that combines multiple biomarkers. When we have subjects longitudinally followed up, it is of primary interest to assess if some baseline measurements predict the time-to-event outcome. Specifically, in this study, systolic blood pressure, diastolic blood pressure, as well as their variation over time, are considered predictive biomarkers, and we assess their predictive ability for certain time-to-event outcomes in terms of the C index. RESULTS: There are a few summary C index differences that are statistically significant in predicting and discriminating certain CVD metric at certain age stage, though some of these differences are altered in the presence of medicine treatment and lifestyle characteristics. The variation of systolic BP measures over time has a significantly different predicting ability comparing with systolic BP measures at certain given time point, for predicting certain survival outcome such as high cholesterol level. CONCLUSIONS: Adult systolic and diastolic BP measurements may have significantly different ability in predicting time to first CVD events. The fluctuation of BP measurements over time may have better association than BP measurement at a single baseline time point, with the time to first CVD events.

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