BACKGROUND:The aim of this study was to evaluate clinico-pathologic specific predictors of recurrence for stage II/III disease. Improving recurrence prediction for resected stage II/III colon cancer patients could alter surveillance strategies, providing opportunities for more informed use of chemotherapy for high risk individuals.METHODS:871 stage II and 265 stage III patients with colon cancers were included. Features studied included surgery date, age, gender, chemotherapy, tumor location, number of positive lymph nodes, tumor differentiation, and lymphovascular and perineural invasion. Time to recurrence was evaluated, using Cox's proportional hazards models. The predictive ability of the multivariable models was evaluated using the concordance (c) index.RESULTS:For stage II cancer patients, estimated recurrence-free survival rates at one, three, five, and seven years following surgery were 98%, 92%, 90%, and 89%. Only T stage was significantly associated with recurrence. Estimated recurrence-free survival rates for stage III patients at one, three, five, and seven years following surgery were 94%, 78%, 70%, and 66%. Higher recurrence rates were seen in patients who didn't receive chemotherapy (p=0.023), with a higher number of positive nodes (p<0.001). The c-index for the stage II model was 0.55 and 0.68 for stage III.CONCLUSIONS:Current clinic-pathologic information is inadequate for prediction of colon cancer recurrence after resection for stage II and IIII patients. Identification and clinical use of molecular markers to identify the earlier stage II and III colon cancer patients at elevated risk of recurrence are needed to improve prognostication of early stage colon cancers.

Orientador: Juliany Gomes Quitzan / Resumo: O carcinoma de células escamosas (CCE) é uma neoplasia epitelial originada dos queratinócitos da pele de cães. Sua etiologia está relacionada à exposição a raios solares ultravioletas, o que o coloca como uma das neoplasias mais frequentes em países tropicais de clima quente. O CCE cutâneo tem comportamento invasivo local, baixa capacidade de metástase e frequentemente encontra-se associado à ceratose actinica. Neste estudo, objetivou-se avaliar o efeito do tratamento pré-operatório com piroxicam (Px) na expressão de COX-2 e Ki67, indicadores de inflamação e proliferação celular, respectivamente, em cães acometidos por CCE cutâneo. Além disso, o intervalo livre de doença (ILD) por um período de pelo menos 180 dias após excisão cirúrgica associada a regime de baixa dose diária com Px (0.3mg/kg) e ciclofosfamida (CYC; 15mg/m2) foi determinado nesta população. Não houve diferença estatística significativa na expressão de COX-2 após o tratamento pré-cirúrgico com Px; no entanto, houve diminuição no índice proliferativo marcado com Ki67 (P<0.05). Não foi encontrada alteração significativa no ILD no grupo tratado com Px e CYC (160 dias), quando comparado com o grupo controle retrospectivo (145 dias), tratado somente com ressecção cirúrgica. Não houve diferença estatística no ILD quando analisados o grau histológico, índice mitótico, tempo de evolução, metástase de linfonodos e o comprometimento das margens cirúrgicas. Adicionalmente, cães com estadiamento T4, independente do tratam... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Squamous cell carcinoma (SCC) is an epithelial neoplasm that arises from skin keratinocytes of the dogs. Its etiology is related to ultraviolet sunlight, which puts it as one of the most frequent neoplasm in tropical hot weather countries. Cutaneous SCC have a locally invasive, low metastatic behavior, and is often associated with actinic keratosis. This study aimed to evaluate the effect of pre-operative treatment with piroxicam (Px) on COX-2 and Ki67 expression, indicators of inflammation and cell proliferation, respectively. Besides that, the evaluation of disease-free interval (DFI) of these animals for at least 180 days after surgical excision associated with a daily low-dose treatment with Px (0.3mg/kg) and cyclophosphamide (CYC; 15mg/m2). There was no statically significant difference between COX-2 expression before and after treatment with Px; However, there was a significant decrease on Ki67 proliferative index (P<0.05). No significance was found in DFI when comparing the group treated with Px and CYC (160 days) and the control retrospective group (145 days), treated only with surgical resection. There was no statically difference on DFI when accessing histological grade, mitotic index, evolution time, lymph node metastasis, and incomplete surgical margins (P>0.05). Additionally, dogs with T4 stage, independent of the treatment, were 3.2 and 4.8-fold more likely to develop an early recurrence when comparing with T3 and T2, respectively. The results of this study demo... (Complete abstract click electronic access below) / Mestre

Lily hybrids vary in their ability to produce virus-free (VF) bulblets when grown from virus-infected scales in tissue culture. Asiatic hybrids typically produce a higher percentage of in vitro VF scale bulblets than do Lilium longiflorum cultivars. Three hypotheses concerning the cause of this variation are tested on five lily hybrids: an Asiatic hybrid, two L. longiflorum cultivars, an Oriental hybrid and L. candidum. The first hypothesis states that VF scale bulblets originate from wound tissue that is naturally low in virus concentration and blocks the passage of virus particles from one cell to the next. The second hypothesis says that scale-to-bulblet vascular connections, which serve as virus pathways, occur in hybrids showing high percentages of virus-infected scale bulblets, while connections are absent in those hybrids with low numbers of virus-infected bulblets. The third hypothesis concerns the virus concentration in the scale at the site of bulblet origin: bulblets of hybrids producing large numbers of VF bulblets originate from scale tissues low in virus concentration; bulblets of low percentage VF bulblet hybrids originate from scale tissues high in virus concentration. The first two hypotheses are not supported by the results of this study. First, lily bulblets do not originate from wound tissue. Second, scale-to-bulblet vascular connections consistently occur in 'Enchantment,' an Asiatic hybrid, and occasionally occur in L. candidum. Vascular connections are not detected in the low VF bulblet producers, L. longiflorum cultivars 'Ace' and 'Nellie White,' nor are they seen in the Oriental hybrid 'Stargazer.' Speculative support exists for the third hypothesis concerning uneven virus concentration in the scale. Distinct virus particles are observed with the electron microscope in the double virus-infected L. longiflorum cultivars and not in the other singly-infected lilies. The doubly-infected lilies produce a continuous layer of divided cells in the adaxial subepidermis of the scale where bulblets originate, whereas the singly-infected lilies produce cell division masses in the same area but only beneath forming bulblets. This study suggests that virus particles in L. longiflorum cultivars are more uniformly distributed than particles in the other lilies examined. This occurs not only at the site of bulblet origin but also throughout the scale mesophyll. Whether this is due to concurrent viral infection or to hybrid variation is unknown. / Graduation date: 1992

No description available.

Magister Scientiae - MSc / We review a number of compartmental models in epidemiology which leads to a nonlinear system of ordinary differential equations. We focus an SIR, SEIR and SIS epidemic models with and without vaccination. A threshold parameter R0 is identified which governs the spread of diseases, and this parameter is known as the basic reproductive number. The models have at least two equilibria, an endemic equilibrium and the disease-free equilibrium. We demonstrate that the disease will die out, if the basic reproductive number R0 < 1. This is the case of a disease-free state, with no infection in the population. Otherwise the disease may become endemic if the basic reproductive number R0 is bigger than unity. Furthermore, stability analysis for both endemic and disease-free steady states are investigated and we also give some numerical simulations. The second part of this dissertation deals with optimal vaccination strategy in epidemiology. We use optimal control technique on vaccination to minimize the impact of the disease. Hereby we mean minimizing the spread of the disease in the population, while also minimizing the effort on vaccination roll-out. We do this optimization for the cases of SIR and SEIR models, and show how optimal strategies can be obtained which minimize the damage caused by the infectious disease. Finally, we describe the numerical simulations using the fourth-order Runge-Kutta method. These are the most useful references: [G. Zaman, Y.H Kang, II. H. Jung. BioSystems 93, (2008), 240 − 249], [K. Hattaf, N. Yousfi. The Journal of Advanced Studies in Biology, Vol. 1(8), (2008), 383 − 390.], [Lenhart, J.T. Workman. Optimal Control and Applied to Biological Models. Chapman and Hall/CRC, (2007).], [P. Van den Driessche, J. Watmough. Math. Biosci., 7, (2005)], and [J. Wu, G. R¨ost. Mathematical Biosciences and Engineering, Vol 5(2), (2008), 389 − 391]. / South Africa

>Magister Scientiae - MSc / The influx of infecteds into a population plays a critical role in HIV transmission. These infecteds are known to migrate from one region to another, thereby having some interaction with a host population. This interactive mobility or migration causes serious public health problems. In a very insightful paper by Shedlin et al. [51], the authors discover risk factors but also beneficial factors with respect to fighting human immunodeficiency virus (HIV) transmission, in the lifestyles of immigrants from different cultural backgrounds. These associated behavioral factors with cross-cultural migrations have not received adequate theoretical a attention. In this dissertation we use the compartmental model of Bhunu et al. [6] to form a new model of the HIV epidemic, to include the effect of infective immigrants in a given population. In fact, we first produce a deterministic model and provide a detailed analysis. Thereafter we introduce stochastic perturbations on the new model and study stability of the disease-free equilibrium (DFE) state. We investigate theoretically and computationally how cross-cultural migrations and public health education impacts on the HIV transmission, and how best to intervene in order to minimize the spread of the disease. In order to understand the long-time progression of the disease, we calculate the threshold parameter, known as the basic reproduction number, R0. The basic reproduction number has the property that if R0 is sufficiently small, usually R0 < 1, then the disease eventually vanishes from the population, but if R0 > 1, the disease persists in the population. We study the sensitivity of the basic reproduction number with respect to model parameters. In this regard, if R0 < 1, we show that the DFE is locally asymptotically stable. We also show global stability of the DFE using the Lyapunov method. We derive the endemic equilibrium points of our new model. We intend to counteract the negative effect of the influx of infecteds into a population with educational campaigns as a control strategy. In doing so, we employ optimal control theory to find an optimal intervention on HIV infection using educational campaigns as a basic input targeting the host population. Our aim is to reduce the total number of infecteds while minimizing the cost associated with the use of educational campaign on [0, T ]. We use Pontryagin’s maximum principle to characterize the optimal level of the control. We investigate the optimal education campaign strategy required to achieve the set objective of the intervention. The resulting optimality system is solved numerically using the Runge-Kutta fourth order method. We present numerical results obtained by simulating the optimality system using ODE-solvers in MATLAB program. We introduce randomness known as white noise into our newly formed model, and discuss the almost sure exponential stability of the disease-free equilibrium. Finally, we verify the analytical results through numerical simulations.

No description available.

Stalk rot reaction of maize (Zea mays L.) and its effect on yield was studied using 12 elite inbred parents (A619, A632, B73, H60, H93, H96, Mo17, Oh7B, Pa91, Va17, SS419, Va85) and all possible single crosses among them. The diallel study was conducted at Warsaw, Virginia in 1985. The experimental design was a split-plot with two stalk rot pathogens (Diplodia maydis and Fusarium moniliforme) and a control being the three whole plots and the inbreds described above and their single cross hybrids being the sub-plots. Plots were inoculated with the pathogens approximately three weeks following silking. Stalk rot scores and yield was taken four weeks following inoculation. Analyses of variance and combining ability analyses were performed on stalk rot scores and grain yield. There were no significant differences between the two pathogens for mean stalk rot score, but both were significantly higher in score than the control. Differences among the whole plots for mean yield were not significant. Hybrid/line by pathogen interactions were not significant for yield or stalk rot scores, indicating that the inbreds and their hybrids performed consistently across the pathogens and control. The estimates of GCA and SCA effects for stalk rot score both were significant with the GCA effects being the greater. This should indicate that stalk rot reaction would respond readily to selection in a breeding population. Per plant yields were not affected by the stalk rot treatments. Two Virginia lines, Val7 and Va85, were found to have both high yield and high levels of resistance to stalk rot, and should be good candidates for a breeding program stressing stalk rot resistance. / M.S.

Desde que os vírus de computadores tornaram-se um grave problema para sistemas individuais e corporativos, diversos modelos de disseminação de vírus têm sido usados para explicar o comportamento dinâmico da propagação desse agente infeccioso. Como estratégias de prevenção de proliferação de vírus, o uso de antivírus e sistema de vacinação, têm contribuído para a contenção da proliferação da infecção. Outra forma de combater os vírus é estabelecer políticas de prevenção baseadas nas operações dos sistemas, que podem ser propostas com o uso de modelos populacionais, como os usados em estudos epidemiológicos. Entre os diversos trabalhos, que consideram o clássico modelo epidemiológico de Kermack e Mckendrick, SIR (suscetível - infectado - removido), aplicado ao contexto de propagação de vírus, a introdução de computadores antidotais, como programa antivírus, fornece muitos resultados operacionais satisfatórios. Neste trabalho, o modelo SIRA (suscetível - infectado - removido - antidotal) é estudado considerando a taxa de mortalidade como parâmetro e associado a isso, o parâmetro que recupera os nós infectados é variado de acordo com a alteração da taxa de mortalidade. Nessas condições, a existência dos pontos de equilíbrio livre de infecção são encontrados, mostrando que o modelo é robusto. / Since computer viruses have become a serious problem for individual and corporate systems, several models of virus dissemination have been used to explain the dynamic behavior of the spread of this infectious agent. As prevention strategies for virus proliferation, the use of antivirus and vaccination system, have contributed to contain the proliferation of the infection. Another way to combat viruses is to establish prevention policies based on the operations of the systems, which can be proposed with the use of population models, such as those used in epidemiological studies. Among the several papers, which consider the classic epidemiological model of Kermack and Mckendrick, SIR (susceptible - infected - removed), applied to the context of virus propagation, the introduction of antidotal computers, such as antivirus program, provides many satisfactory operational results. In this work, the SIRA (susceptible - infected - removed - antidotal) model is studied considering the mortality rate as a parameter and associated with this, the parameter that recovers infected nodes is varied according to the change in mortality rate. Under these conditions, the existence of infection free equilibrium points are found, showing that the model is robust.

Com o objetivo de avaliar o significado prognóstico da graduação histológica do Linfoma de Hodgkin tipo Esclerose Nodular (LH EN), proposta pelo British National Lymphoma Investigation, realizamos um estudo retrospectivo que incluiu 69 casos de LH EN. Trinta e cinco casos (51%) foram classificados com EN grau I e 34 (49%) como EN grau II. Remissão completa após o tratamento inicial foi obtida em 85,7% dos casos de EN I e em 82,4% dos casos de EN II (p=0,75). A probabilidade estimada de sobrevida global em 5 anos foi de 67,0% para EN I e de 83,5% para EN II (p = 0,13) e a taxa de sobrevida livre de doença em 5 anos foi de 85,2% versus 87,0%, respectivamente (p = 0,72). Concluímos que a graduação histológica BNLI não esteve associada com o prognóstico do LH EN nesta população / In order to evaluate the prognostic significance of the British National Lymphoma Investigation histological grading system for Nodular Sclerosing Hodgkin´s Lymphoma (NS HL), we retrospectively studied 69 NS HL patients. Thirty five cases (51%) were classified as NS grade I and 34 (49%) as NS grade II. The complete remission rate after initial therapy was 85,7% in the NS I group and 82,4% in the NS II group (p=0,75). The predicted 5-year overall survival rate was 67,0% in the NS I patients and 83,5% in the NS II patients (p = 0,13). The predicted 5-year disease free survival rate for NSI and NSII patients was 85,2% and 87,0%, respectively (p = 0,72). Therefore, we concluded that the BNLI grading system was not associated with the prognosis of NS HL in this uniformly treated population