Modelos de sobrevivência com fração de cura e erro de medida nas covariáveis

In this work, we study the survival cure rate model proposed by Yakovlev et al. (1993), based on a competing risks structure concurring to cause the event of interest, and the approach proposed by Chen et al. (1999), where covariates are introduced to model the risk amount. We focus the measurement error covariates topics, considering the use of corrected score method in order to obtain consistent estimators. A simulation study is done to evaluate the behavior of the estimators obtained by this method for finite samples. The simulation aims to identify not only the impact on the regression coefficients of the covariates measured with error (Mizoi et al. 2007) but also on the coefficients of covariates measured without error. We also verify the adequacy of the piecewise exponential distribution to the cure rate model with measurement error. At the end, model applications involving real data are made

Modelos de sobrevivência com fração de cura e omissão nas covariáveis

In this work we study the survival cure rate model proposed by Yakovlev (1993) that are considered in a competing risk setting. Covariates are introduced for modeling the cure rate and we allow some covariates to have missing values. We consider only the cases by which the missing covariates are categorical and implement the EM algorithm via the method of weights for maximum likelihood estimation. We present a Monte Carlo simulation experiment to compare the properties of the estimators based on this method with those estimators under the complete case scenario. We also evaluate, in this experiment, the impact in the parameter estimates when we increase the proportion of immune and censored individuals among the not immune one. We demonstrate the proposed methodology with a real data set involving the time until the graduation for the undergraduate course of Statistics of the Universidade Federal do Rio Grande do Norte

Estimação em modelos de tempo de falha acelerado para dados de sobrevivência correlacionados

We presented in this work two methods of estimation for accelerated failure time models with random e_ects to process grouped survival data. The _rst method, which is implemented in software SAS, by NLMIXED procedure, uses an adapted Gauss-Hermite quadrature to determine marginalized likelihood. The second method, implemented in the free software R, is based on the method of penalized likelihood to estimate the parameters of the model. In the _rst case we describe the main theoretical aspects and, in the second, we briey presented the approach adopted with a simulation study to investigate the performance of the method. We realized implement the models using actual data on the time of operation of oil wells from the Potiguar Basin (RN / CE).

A cafeína exerce efeitos positivos sobre a memória tipo episódica em ratos adultos sem influenciar a sobrevivência neural no giro dentado

The caffeine is a mild psychostimulant that has positive cognitive effects at low doses, while promotes detrimental effects on these processes at higher doses. The episodic-like memory can be evaluated in rodents through hippocampus-dependent tasks. The dentate gyrus is a hippocampal subregion in which neurogenesis occurs in adults, and it is believed that this process is related to the function of patterns separation, such as the identification of spatial and temporal patterns when discriminating events. Furthermore, neurogenesis is influenced spatial and contextual learning tasks. Our goal was to evaluate the performance of male Wistar rats in episodic-like tasks after acute or chronic caffeine treatment (15mg/kg or 30mg/kg). Moreover, we assessed the chronic effect of the caffeine treatment, as well as the influence of the hippocampus-dependent learning tasks, on the survival of new-born neurons at the beginning of treatment. For this purpose, we used BrdU to label the new cells generated in the dentate gyrus. Regarding the acute treatment, we found that the saline group presented a tendency to have better spatial and temporal discrimination than caffeine groups. The chronic caffeine group 15 mg/kg (low dose) showed the best discrimination of the temporal aspect of episodic-like memory, whereas the chronic caffeine group 30mg/kg (high dose) was able to discriminate temporal order, only in a condition of greater difficulty. Assessment of neurogenesis using immunohistochemistry for evaluating survival of new-born neurons generated in the dentate gyrus revealed no difference among groups of chronic treatment. Thus, the positive mnemonic effects of the chronic caffeine treatment were not related to neuronal survival. However, another plastic mechanism could explain the positive mnemonic effect, given that there was no improvement in the acute caffeine groups

Efeitos da sinalização via creb sobre a sobrevivência e diferenciação meuronal

The cortical development requires a precise process of proliferation, migration, survival and differentiation of newly formed neurons to finally achieve the development of a functional network. Different kinases, such as PKA, CaMKII, MAPK and PI3K, phosphorylate the transcription factors CREB, and thus activate it, inducing CREB-dependent gene expression. In order to identify the involvement of such signaling pathways mediated by CREB over neuronal differentiation and survival, in vitro experiments of cell culture were conducted using pharmacological kinase inhibitors and genetic techniques to express different forms of CREB (A-CREB and CREB-FY) in cortical neurons. Inhibition of PKA and CaMKII decreased the length of neuronal processes (neurites); whereas inhibition of MAPK did not affect the length, but increased the number of neurites. Blockade of PI3K do not appear to alter neuronal morphology, nor the soma size changed with the kinase blockades. CREB activation (CREB-FY) along with MAPK and PI3K blockades presented a negative side effect over neuritic growth and the expression of A-CREB leaded to a significant decrease in neuronal survival after 60h in vitro and mimicked some of the effects on neuronal morphology observed with PKA and CaMKII blockade. In summary the signaling through CREB influences the morphology of cortical neurons, particularly when phosphorylated by PKA, and CREB signaling is also important for survival of immature neurons prior to the establishment of fully functional synaptic contacts. Our data contribute to understanding the role of CREB signaling, activated by different routes, on survival and neuronal differentiation and may be valuable in the development of regenerative strategies in different neurological diseases

Fatores associados à condição de saúde bucal de pacientes internados em hospitais públicos do município de Natal-RN

The hospitalization is an event that can attack any person, independent of gender, race, social and economical condition. Last year, the prevalence of hospitalization was 8.1 for 100 inhabitants and the average time of hospitalization was 8.5 days for each patient one in Natal city. Therefore, an important point is whether the attention to the patients during the permanence in these health establishments incorporates the health integral model suggested by the principles proposed by the National Health System in Brazil (SUS), with actions of promotion and protection by different kinds of professionals, beside those called convalescence. Then, the aim of this study was to evaluate the patient s oral health conditions hosted in public hospitals of the Natal city, looking for to establish its relationship with several risk factors by two dimensions: the characteristics of the hospitalization and the patient s general and economical conditions. We accomplished a cross-sectional study with 205 patients distributed among the hospitals Onofre Lopes, Giselda Trigueiro and Monsenhor Walfredo Gurgel, looking for to know the socio-demographic characteristics, the food habits and of oral hygiene and the conditions of oral health, through the Visible Plaque Index and Gingival Bleeding Index. We observed that the conditions of the patient s oral health interned at public hospitals of reference of the municipal district of Natal is bad, existing accumulation of dental plaque and, consequently, a great number of patients with gingival bleeding. However, the time of hospitalization and its reason, the type of medicine used in this time and the toothbrush frequency were not configured as risk factors for this oral health condition

Hipossalivação e seus fatores de risco em idosos funcionalmente independentes e não institucionalizados

The aim of this study was to investigate the risk factors related to hyposalivation among non-institutionalized independently living elderly people, living in Natal-RN, Brazil. The study was a control-case type and the data collection was accomplished by carrying a questionnaire, oral examination and a non-stimulated and stimulated sialometry. The cases were identified by values of salivary flow rate <0,1mL/min and stimulated ≤ 0,5 mL/min, and the controls were by observing the values of sialometry that were bigger than the previously defined parameters. Age and gender were used as pairing variables. The data were analyzed using X2 (α = 0,05) and odds ratio. The sample was composed of 98,1% female and 1,9% male, with mean age 68. There was not association between hyposalivation and the following studied variables: income, schooling, profession, dwelling conditions, domiciliary density, illness, number of teeth and use of prothesis. However, a link was found between hyposalivation and smoking frequency in the passet (OR=5,14), indicating that, referring to elderly people, the tabagism frequency habit was a risk factor to the studied condition. Therefore, refering to non-institutionalized independently elderly people, economic-social-demographic conditions, general and bucal health, diet and habits such as alcoholism have been not risk factors to hyposalivation. However, people that have been smoking have more risk to have the studied conditions

Edentulismo funcional e seus fatores de risco em adultos

The purpose of this study was to investigate the risk factors to the functional edentulism in adults aged 35 a 44 years old of Natal-RN, 278 adults took part in the study. They were all selected from a previous dental loss prevalence study thus being complemented by an active research. The study was a case-control based and data collection was made though a survey as well as with a clinical examination. The cases were identified through individuals with 20 or more teeth. Age and gender were used as variables of pairing off. The data was analyzed through chi-square, significant level of 95% to the checking of its force associations. The independent variables were grouped in three levels. The first one, more macro, is related to the region where the individual lives, which was also related to the second level, the family-based one, linked with a third level, at this low socio-economical level, where the domiciliary density was favorable, living in capital cities, regions with prime sanitary condicitions, with predominant possibility of accessing the public dental service, but in despite of this, only looking for this service when tooth ache is felt, where preferentially an aid dressing treatment is executed in detriment of preventive procedures. From all the samples, less than 25% of the individuals make use of tobacco and alcoholic beverages for quite a number of years. There was an association of functional edentulism with all the studied variables in a regional method. In the family-based with Critério Brasil (OR=4,45) and monthly wages (OR=9,62) and to an to an individual level, the associations took place with the current use of kind of attendance (OR=1,78), looks for dressing treatment (OR=2,51), does not look for preventive treatment (OR=3,31), pain as the main cause of demand (OR=1,92), previous treatment as the demanding reason for dental service (OR+0,28), interval of the last visit to the dental service (OR=1,35) and when advise was received (OR=1,66). It was noticed from the results that the functional edentulism is much more expressive in those families which live in environments with precarious social economical sanitary conditions. Such conditions seem to have a direct influence upon the family social economical conditions which are also shown in detriment to functional edentulism. In the same way, the collection of variants influence the social economical conditions of the individual, as well as the kind of dental service searched by them, the reason of the search and the interval of the last visit to the dental service were strong determiners to the functional edentulism. Beyond that, individual habits like the use of tobacco and its frequency on its previous use influenced in a significant way the existence of functional edentulism in the studied population

Prevalência e fatores de risco à persistência de hábitos bucais de sucção não nutritiva em crianças de 3 a 5 anos de idade

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Prevalência e fatores associados a lesões labiais e periorais decorrentes da exposição solar em trabalhadores de praia

This study aimed to verify the prevalence of lip and perioral lesions in worker who were under sunshine on the beaches of Natal/RN and to investigate possible associations of these with sociodemographic, occupational and general health variables. For this, 362 individuals who had one of the urban beaches (Ponta Negra / Environment / Redinha) in the city of Natal/RN as a working environment in the study. We excluded people under 18 years old. Data collection was done through epidemiological analysis and extra-oral validated questionnaire with questions that characterize socioeconomic and demographic factors, occupational exposure and general health. The male subjects (72.6%) were the majority in the sample. The people who worked directly exposed to high peaks of ultraviolet radiation, as well as informal workers predominated. Considering the total sample of individuals, ephelides in the perioral region (33.7%) and labial region (24.0%), solar lentigo perioral (15.2%) and actinic cheilitis (13.8%) stood out as the most prevalent lesions. Indoor workers and those who had a habit occurrence of injuries by 19% and 21% respectively higher when compared to outdoor workers and people without habits. The variable use of cap / hat was associated with the presence of cold sores (Qui2 = 1,328, p = 0,058). On the threshold of significance, the type of work was also associated with lesions in lip occurrence (p = 0,042). Men showed a lower incidence of perioral lesions when compared to female workers (PR=0,716, p valor = 0,002). The present study showed high prevalence of lip and perioral lesions. The premalignant lesions were the most identified, both as in lip skin. It is important therefore to be encouraged to adopt protective measures against excessive sun exposure, fairly and consistently

Influência de fatores de risco na prevalência de hábitos bucais deletérios em crianças de 0 a 5 anos na cidade do Natal-RN

Literature has demonstrated to the narrow relation between deleterious habits and the occurrence of malocclusion in minors of 5 years. The existence of these habits, however, already considered as risk factors, having also, its determinative ones, which present cultural dimensions and economic social, many of them related to the parents of the child, having in account that such habits if develop in phases in which the child establish a narrow relation of dependence. This study it had an objective to investigate the prevalence of deleterious buccal habits in children and its relation with the economic social and characteristics of the parents. It was developed an epidemiologist study of transversal character with interview, through daily pay-tested form, with 218 parents in the day of the National Campaign of Vaccination. In the cast of the variable that had composed the study, they had been used, as changeable dependents, the use of the baby's bottle, bottle and the digital suction, being considered as outcomes of the research. Amongst the independent variable, the economic social factors (type of occupation, number of children, civil state, sort, schooling and age) and staffs of the parents (self perception in oral health) had entered as the variable to be analyzed in the problems of the infantile odontology. The collected data had been submitted to the analysis descriptive and inferential statistics, being used the test qui-square and the analysis of the possibility reasons. As main results, it was found that breast feeding before the six months if presents as one of the main factors of risk for the use of baby's bottle (p< 0.001, OR= 2.8, I.C= 1.589 4.906), bottle (p< 0.001, OR= 3.7, I.C.= 2.076 6.624) and digital suction (p< 0.014, OR= 3.5, I.C.= 1.225 10.181). From the data found, one concludes that breast-feeding is considered a primordial factor for not the installation of deleterious oral habits and that the economic social and cultural factors can reflect in central way in the performance of this act

Exprassão imuno-histoquímica dos fatores de reabsorção óssea em lesões centrais e periféricas de células gigantes

The Giant Cell Lesions, both the Central Giant Cells Lesions (CGCL) as the Peripheral Giant Cells Lesions (PGCL), correspond to a group of oral lesions that are histologically similar entities; however they show a variable clinical behaviour. The purpose of this study was to compare the immunohistochemical expression of bone resorption factors RANK (Receptor Activator of Nuclear Factor kappa B), RANKL (Receptor Activator of Nuclear Factor kappa B Ligand) and OPG (Osteoprotegerin) between CGCL and PGCL. Additionally, these bone resorption factors were examined in terms of aggressiveness of these lesions. The sample consisted of 61 cases, 30 cases of PGCL and 31 CGCL (16 non-aggressive and 15 aggressive). The analysis was performed by quantification of mononuclear cells (MO) and giant multinucleated cells (CG) immunopositive to anti-RANK, anti-RANKL and anti-OPG antibodies in 10 fields. Moreover, according to the proportion between the amount of cells positive for RANKL and OPG, the cases were categorized into: RANKL>OPG, OPG>RANKL e RANKL=OPG. CGCL showed a higher amount of MO (p=0.002) and total cells (p=0.003) both positives to RANKL compared with the PGCL. Additionally, the CGCL revealed a significant association with the ratio of RANKL>OPG (p=0.001). Analysis of the bone resorption factors revealed no significant differences between aggressive and non-aggressive CGCL (p>0.05). It was observed a positive correlation between the markers themselves, and a negative correlation between lesion size and quantity of OPG positive MO cells (p=0,004) and total cells (p=0,009). Through these results, we suggest that the greatest CGCL resorptive potential compared to the PGCL, may have occurred to the high expression of RANKL. Furthermore differences in the biological behavior of aggressive and non-aggressive CGCL appear to be related to the expression of these bone resorption factors

Imunoexpressão de fatores reguladores da osteoclastogênese na doença periodontal em humanos e sua relação com os parâmetros clínicos

Periodontal disease is an infection initiated by oral periodontal pathogens that trigger an immune response culminating in tissue destruction. This destruction is mediated by the host by inducing the production and activation of lytic enzymes, cytokines and the stimulation of osteoclastogenesis. The aim of this study was to compare the immunohistochemical expression of factors involved in bone resorption, RANKL (Ligand Receptor Activator of Nuclear Factor kappa B), OPG (Osteoprotegerin) and TNF-α (tumor necrosis factor alpha) between the gingival healthy, gingivitis and chronic periodontitis and correlate them with clinical parameters. The sample consisted of 83 cases and 12 clinically healthy gums, 42 gingivitis and 29 periodontitis, from 74 adolescent and adult patients with a mean age of 35 years, without systemic changes and non-smokers, predominantly female and race brown. There was no statistically significant difference for the expression of anti-RANKL (p = 0.581) and RANKL / OPG ratio (p = 0.334) when comparing the three conditions, but the anti-OPG and anti-TNF-α showed statistically significant between the types of injury (p = 0.001 and p <0.001, respectively), showing greatest expression in periodontitis. In cases of periodontitis, the variable clinical attachment loss (PIC) was statistically significant and positive correlation, respectively, with immunostaining of anti-RANKL (p = 0.002, p = 0.001 and r = 0.642), anti-OPG (p = 0.018, p = 0.014 and r = 0.451), anti-TNF-α (p = 0.032, p = 0.014 and r = 0.453) and the percentage ratio of RANKL / OPG (p = 0.018, p = 0.002 and r = 0.544). The tooth mobility (MB) showed a statistically significant difference only with immunohistochemical anti-RANKL (p = 0.026), and probing depth (PD) was positively correlated with anti-RANKL (p = 0.028 and r = 0.409), both in cases of periodontitis. Only in cases of gingivitis TNF-α was positively correlated with RANKL (p = 0.012 and r = 0.384) and the RANKL / OPG ratio (p = 0.027 and r = 0.341). Given these results, we conclude that the greatest expression of TNF-α in periodontitis demonstrates a relationship with the progression and severity of periodontal disease and the correlation between all antibodies and clinical attachment loss demonstrates their involvement in periodontal bone resorption

Análise de fatores clínico-demográficos, psicológicos, hormonais e genéticos na síndrome da ardência bucal e ardor bucal secundário

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Fatores de influência na produção de leite bovino sobre os níveis da contagem bacteriana total

The objective of this study was to evaluate the influence of milking procedures on the levels of total bacterial count (TBC) in bovine milk. In the first study the influences of procedures for hygienic milking, cleaning of milking equipment and milk cooling tanks on the TBC levels were evaluated. Four bulk samples of milk were collected from each tank in eight properties for TBC analysis, employing the flow cytometry method. A questionnaire was applied in each property to assess the current situation of milking procedures on each production system that took part on this research, followed by training of employees in good agricultural practices in the production of milk and monitoring of the TBC measurements. The methodology for analysis of longitudinal data was considered, focusing on random effects models. The results showed that the handling procedures for milking and the cleanliness of the cooling tank contributed to a further reduction in the levels of TBC raw milk cooling tanks. The second study aimed to describe the percentage of the properties that comply with the Normative Instruction Nº 51 (Brazil s IN 51) with regard to total bacterial count (TBC) in bovine milk. The study was conducted from January 2010 to July 2011. Milk samples were collected from the eight properties selected for TBC analysis by the flow cytometry method. Again, on each property a questionnaire was applied to assess the current situation of milking procedures on each production system that took part on this research, followed by training of employees in good agricultural practices in the production of milk and monitoring of the TBC measurements. The methodology of marginal models based on Generalized Estimate Equations (GEEs) was followed in the statistical analysis. The results showed that the handling procedures of the milking and the cleanliness of the cooling tanks contributed to a considerable percentage of the properties that reached the limits of TBC established by IN 51