A logical framework to study concept-learning biases in the presence of multiple explanations.

When people seek to understand concepts from an incomplete set of examples and counterexamples, there is usually an exponentially large number of classification rules that can correctly classify the observed data, depending on which features of the examples are used to construct these rules. A mechanistic approximation of human concept-learning should help to explain how humans prefer some rules over others when there are many that can be used to correctly classify the observed data. Here, we exploit the tools of propositional logic to develop an experimental framework that controls the minimal rules that are simultaneously consistent with the presented examples. For example, our framework allows us to present participants with concepts consistent with a disjunction and also with a conjunction, depending on which features are used to build the rule. Similarly, it allows us to present concepts that are simultaneously consistent with two or more rules of different complexity and using different features. Importantly, our framework fully controls which minimal rules compete to explain the examples and is able to recover the features used by the participant to build the classification rule, without relying on supplementary attention-tracking mechanisms (e.g. eye-tracking). We exploit our framework in an experiment with a sequence of such competitive trials, illustrating the emergence of various transfer effects that bias participants' prior attention to specific sets of features during learning.

Flow Cytometry Immunophenotyping for Diagnostic Orientation and Classification of Pediatric Cancer Based on the EuroFlow Solid Tumor Orientation Tube (STOT).

Early diagnosis of pediatric cancer is key for adequate patient management and improved outcome. Although multiparameter flow cytometry (MFC) has proven of great utility in the diagnosis and classification of hematologic malignancies, its application to non-hematopoietic pediatric tumors remains limited. Here we designed and prospectively validated a new single eight-color antibody combination-solid tumor orientation tube, STOT-for diagnostic screening of pediatric cancer by MFC. A total of 476 samples (139 tumor mass, 138 bone marrow, 86 lymph node, 58 peripheral blood, and 55 other body fluid samples) from 296 patients with diagnostic suspicion of pediatric cancer were analyzed by MFC vs. conventional diagnostic procedures. STOT was designed after several design-test-evaluate-redesign cycles based on a large panel of monoclonal antibody combinations tested on 301 samples. In its final version, STOT consists of a single 8-color/12-marker antibody combination (CD99-CD8/numyogenin/CD4-EpCAM/CD56/GD2/smCD3-CD19/cyCD3-CD271/CD45). Prospective validation of STOT in 149 samples showed concordant results with the patient WHO/ICCC-3 diagnosis in 138/149 cases (92.6%). These included: 63/63 (100%) reactive/disease-free samples, 43/44 (98%) malignant and 4/4 (100%) benign non-hematopoietic tumors together with 28/38 (74%) leukemia/lymphoma cases; the only exception was Hodgkin lymphoma that required additional markers to be stained. In addition, STOT allowed accurate discrimination among the four most common subtypes of malignant CD45- CD56++ non-hematopoietic solid tumors: 13/13 (GD2++ numyogenin- CD271-/+ nuMyoD1- CD99- EpCAM-) neuroblastoma samples, 5/5 (GD2- numyogenin++ CD271++ nuMyoD1++ CD99-/+ EpCAM-) rhabdomyosarcomas, 2/2 (GD2-/+ numyogenin- CD271+ nuMyoD1- CD99+ EpCAM-) Ewing sarcoma family of tumors, and 7/7 (GD2- numyogenin- CD271+ nuMyoD1- CD99- EpCAM+) Wilms tumors. In summary, here we designed and validated a new standardized antibody combination and MFC assay for diagnostic screening of pediatric solid tumors that might contribute to fast and accurate diagnostic orientation and classification of pediatric cancer in routine clinical practice.

A theory of memory for binary sequences: Evidence for a mental compression algorithm in humans.

Working memory capacity can be improved by recoding the memorized information in a condensed form. Here, we tested the theory that human adults encode binary sequences of stimuli in memory using an abstract internal language and a recursive compression algorithm. The theory predicts that the psychological complexity of a given sequence should be proportional to the length of its shortest description in the proposed language, which can capture any nested pattern of repetitions and alternations using a limited number of instructions. Five experiments examine the capacity of the theory to predict human adults' memory for a variety of auditory and visual sequences. We probed memory using a sequence violation paradigm in which participants attempted to detect occasional violations in an otherwise fixed sequence. Both subjective complexity ratings and objective violation detection performance were well predicted by our theoretical measure of complexity, which simply reflects a weighted sum of the number of elementary instructions and digits in the shortest formula that captures the sequence in our language. While a simpler transition probability model, when tested as a single predictor in the statistical analyses, accounted for significant variance in the data, the goodness-of-fit with the data significantly improved when the language-based complexity measure was included in the statistical model, while the variance explained by the transition probability model largely decreased. Model comparison also showed that shortest description length in a recursive language provides a better fit than six alternative previously proposed models of sequence encoding. The data support the hypothesis that, beyond the extraction of statistical knowledge, human sequence coding relies on an internal compression using language-like nested structures.

Towards a more flexible language of thought: Bayesian grammar updates after each concept exposure.

Recent approaches to human concept learning have successfully combined the power of symbolic, infinitely productive rule systems and statistical learning to explain our ability to learn new concepts from just a few examples. The aim of most of these studies is to reveal the underlying language structuring these representations and providing a general substrate for thought. However, describing a model of thought that is fixed once trained is against the extensive literature that shows how experience shapes concept learning. Here, we ask about the plasticity of these symbolic descriptive languages. We perform a concept learning experiment that demonstrates that humans can change very rapidly the repertoire of symbols they use to identify concepts, by compiling expressions that are frequently used into new symbols of the language. The pattern of concept learning times is accurately described by a Bayesian agent that rationally updates the probability of compiling a new expression according to how useful it has been to compress concepts so far. By portraying the language of thought as a flexible system of rules, we also highlight the difficulties to pin it down empirically.

Breast Implant-Associated Anaplastic Large-Cell Lymphoma: Why Must We Learn About It?

Breast implant-associated anaplastic large-cell lymphoma (BIA-ALCL) is a rare, breast implant-associated T-cell lymphoma in which CD30 is expressed and anaplastic lymphoma kinase (ALK) expression is absent. However, despite the low risk of developing the disease, more information on BIA-ALCL is necessary, because the number of women with breast implants has been increasing worldwide; Brazil is one of the main markets for this type of implant. The objectives of this review are to clarify the issue of BIA-ALCL occurrence after risk-reducing mastectomy, to show the importance of this disease, and to raise awareness among the medical community about this rare pathologic condition. In 2016, BIA-ALCL was included by WHO in the new classification of lymphomas, and this demonstrates the attention that medical entities should give to this disease. Thus, awareness about BIA-ALCL must be broadened among the medical societies and regulatory authorities, both to foster better approaches to this disease, which should be evaluated in a multidisciplinary manner, and to provide better knowledge among health care professionals and the target population about the use of implants.

Mutation profiling in the PIK3CA, TP53, and CDKN2A genes in circulating free DNA and impalpable breast lesions.

Breast impalpable lesions have become a clinical dilemma because they are small, presenting a heterogeneous cellular phenotype. The aim of this study was to evaluate the mutational profile of the PIK3CA, TP53, and CDKN2A genes, comparing the mammary tissue with the respective circulating free DNA (cfDNA). The PIK3CA, TP53, and CDKN2A genes were sequenced (PCR-Sanger) in 58 women with impalpable lesions (49 malignant and 9 benign) with the respective cfDNA. The chi-square or Fisher's exact test was used to evaluate statistical significance between the clinical variables and mutational profile. A total of 51 out of 58 samples generated successful mutation profiles in both breast lesion and cfDNA. Of the 37 mutations detected, 10 (27%) and 16 (43%) mutations were detected in benign and malignant breast lesions, respectively, while 2 (5%) and 9 (24%) were found in cfDNA of women with benign and malignant lesions, respectively. The lymph node involvement with mutations in the PIK3CA in malignant lesions (P = 0.001), and the relationship between mutations in PIK3CA, comparing ductal tumors with benign lesions (P = 0.05), were statistically significant. This study detected different mutations in PIK3CA, TP53, and CDKN2A genes, which represent, in part, the heterogeneity of impalpable lesions. The results confirm that more studies should be conducted on the functional role of cfDNA in the impalpable lesions.

Bayesian validation of grammar productions for the language of thought.

Probabilistic proposals of Language of Thoughts (LoTs) can explain learning across different domains as statistical inference over a compositionally structured hypothesis space. While frameworks may differ on how a LoT may be implemented computationally, they all share the property that they are built from a set of atomic symbols and rules by which these symbols can be combined. In this work we propose an extra validation step for the set of atomic productions defined by the experimenter. It starts by expanding the defined LoT grammar for the cognitive domain with a broader set of arbitrary productions and then uses Bayesian inference to prune the productions from the experimental data. The result allows the researcher to validate that the resulting grammar still matches the intuitive grammar chosen for the domain. We then test this method in the language of geometry, a specific LoT model for geometrical sequence learning. Finally, despite the fact of the geometrical LoT not being a universal (i.e. Turing-complete) language, we show an empirical relation between a sequence's probability and its complexity consistent with the theoretical relationship for universal languages described by Levin's Coding Theorem.

Epithelioid hemangioendothelioma: 15 years at the National Cancer Institute. Literature review / Hemangioendotelioma epitelioide: 15 anos no Instituto Nacional de Câncer. Revisão da literatura

INTRODUCTION: Hemangioendotheliomas are locally aggressive vascular tumors with intermediate malignity and metastasis risk. The epithelioid variant, the most aggressive one, equally affects men and women at any age and it is rare in children. It occurs as a solitary tumor, which is usually painful, affecting superficial or deep soft tissues. Furthermore, it is less frequent in the liver, lung, bones, skin, lymph nodes and central nervous system. Microscopically, they present epithelioid cells with intracytoplasmic vacuoles, low mitotic activity and little or no necrosis. Additionally, its vascular nature is confirmed by immunohistochemical studies (CD31, CD34 and factor VIII). OBJECTIVE, MATERIAL AND METHODS: Through search in the archives of the Pathology Division of the National Cancer Institute (Instituto Nacional de Câncer [INCA]) from 1996 to 2011, 13 cases of epithelioid hemangioendothelioma (HEE) were identified and analyzed. RESULTS AND DISCUSSION: seven cases occurred in male patients and six in female patients, mean age 42 years, ranging from 7-66. The most common locations were: soft tissue (three patients; 23%); head and neck, mediastinum, bone and lung (two patients each; 15%); liver and lymph nodes (one patient each; 8%). There was clinical follow-up of nine patients: five were alive and disease-free (one to six years after diagnosis); three out of four patients with aggressive disease progressed to death (one month to five years after diagnosis); one relapsed two years after diagnosis and is alive with disease. CONCLUSION: This series of 13 cases of HEE, whose diagnoses were based on morphological and/or immunohistochemical analyses, demonstrates the different patterns of clinical presentation and biologic behavior of this disease.

INTRODUÇÃO: O hemangioendotelioma é um tumor vascular de malignidade intermediária, localmente agressivo e com risco de metástase. A variante epitelioide, a mais agressiva, acomete igualmente homens e mulheres em qualquer idade e é rara na infância. Apresenta-se como tumoração solitária, geralmente dolorosa, em partes moles, superficiais ou profundas; menos frequentemente, acomete fígado, pulmão, ossos, pele, linfonodos e sistema nervoso central. Microscopicamente, mostram células epitelioides com vacúolos intracitoplasmáticos, baixa atividade mitótica, pouca ou nenhuma necrose, tendo sua natureza vascular comprovada por estudos imuno-histoquímicos (CD31, CD34, Fator VIII). OBJETIVOS E MATERIAL E MÉTODOS: Por meio de busca nos arquivos da Divisão de Patologia (DIPAT) do Instituto Nacional de Câncer (INCA), de 1996 a 2011, foram encontrados e revisados 13 casos de hemangioendotelioma epitelioide (HEE). RESULTADOS E DISCUSSÃO: Sete casos ocorreram em homens e seis, em mulheres, com idade média de 42 anos, variando de 7 a 66 anos de idade. As localizações mais frequentes foram partes moles (três pacientes; 23%); cabeça-pescoço, mediastino, osso e pulmão, (dois pacientes cada; 15%); fígado e linfonodo (um paciente cada; 8%). Houve seguimento clínico de nove pacientes: cinco estavam vivos e livres de doença (de um a seis anos após o diagnóstico); dos quatro pacientes que apresentaram HEE agressiva, três evoluíram a óbito com doença (de um mês a cinco anos) e um recidivou dois anos após o diagnóstico e está vivo com a doença. CONCLUSÃO: Esta série de 13 casos de HEE, cujos diagnósticos foram firmados em bases morfológicas e/ou imuno-histoquímicas, demonstra os diferentes padrões de apresentação clínica e o comportamento biológico da doença.

Relationship of Epstein-Barr virus and interleukin 10 promoter polymorphisms with the risk and clinical outcome of childhood Burkitt lymphoma.

Epstein-Barr virus (EBV) is an important environmental factor associated to the development of Burkitt lymphoma (BL) in endemic and intermediate risk regions. However, little is known about the contribution of genetic constitution to the development and clinical response of the disease. The aim of this work was to investigate the role of EBV and Interleukin 10 (IL10) single nucleotide polymorphisms (-1082A/G, -819C/T, -592C/A) and microsatellites (IL10.R and IL10.G) in susceptibility and clinical outcome in pediatric BL patients, in a region with intermediate EBV association frequency. The frequencies of IL10 promoter Single nucleotide polymorphisms -1082A/G, -819C/T, -592C/A, and IL10.R and IL10.G microsatellites were compared in 62 pediatric patients and 216 healthy donors. IL10 -1082GG and GCC/GCC genotypes were more frequent in patients than in controls, and associated to a higher risk of BL development (GG genotype OR 2.62, 95% CI, 1.25-5.51; P = 0.008; Pc = 0.024). EBV was detected in tumor samples by EBER-ISH in 54.1% of cases. EBV+ patients exhibited a better event free survival (EFS) (P = 0.019) than EBV- patients. Carriers of IL10 R3-GCC had worse EFS (P = 0.028). Our results suggest a risk effect and an independent prognostic value of IL10 polymorphisms and EBV in childhood BL patients.

Centroblastic diffuse large B cell lymphoma displays distinct expression pattern and prognostic role of apoptosis resistance related proteins.

Centroblastic diffuse large B cell lymphoma (DLBCL) samples were analyzed by immunohistochemistry to evaluate the expression of p53, Bcl-2, Survivin, XIAP, and Ki-67. Survivin was the only protein which expression exhibited a trend for impact in progression-free (p = .077) and overall survival (p = .054). In the Mann-Whitney test, Survivin expression correlated with a negative overall survival (p = .045). These results appeared to be intimately related to Survivin cytoplasmic localization. Moreover, the anti-apoptotic proteins Bcl-2 and Survivin were less frequent in centroblastic DLBCL. Our results indicate that centroblastic DLBCL may be a disease with characteristic biology and clinical course and, therefore, specific prognostic factors.

Involvement of signaling molecules in the prediction of response to imatinib treatment in metastatic GIST patients.

Imatinib therapy has undoubtedly contributed to the treatment of metastatic gastrointestinal stromal (GIST) tumors that were previously untreatable. However, disease progression during treatment with tyrosine kinase inhibitors remains an issue in clinical practice not fully explained by KIT and PDGFRA mutation status. We investigated the role of three important signaling molecules (insulin-like growth factor 1 receptor [IGF1R], protein kinase C-θ [PKCθ], and Raf kinase inhibitor protein [RKIP]) that have been implicated in GIST pathogenesis as potential biomarkers for prediction of response to imatinib treatment. We retrospectively reviewed 76 patients with metastatic GIST submitted to imatinib treatment between 2002 and 2007, and analyzed 63 of them. Insulin-like growth factor 1, total PKCθ, phosphorylated PKCθ, and RKIP immunohistochemical expression were correlated with objective response to imatinib treatment and progression-free and overall survival. Median follow-up was 31.2 mo (95% confidence interval, 26.3-36.1 mo). There was a statistically significant association between IGF1R expression and type of response to imatinib treatment (P = 0.05)-that is, higher IGF1R expression was related to lower objective response. However, IGF1R higher expression did not affect progression-free and overall survival. Insulin-like growth factor 1, but not PKCθ and RKIP, emerges as a potential biomarker for prediction of response to imatinib treatment in metastatic GISTs. Validation studies are warranted.

Tumor estromal gastrointestinal: análise de 146 casos do centro de referência do Instituto Nacional do Câncer - INCA / Gastrointestinal stromal tumor: analysis of 146 cases of the center of reference of the National Cancer Institute - INCA

OBJETIVO: Avaliar os resultados do tratamento de GIST no INCA. MÉTODOS: Análise retrospectiva de todos os casos de GIST tratados no INCA no período de 1997 a 2009. RESULTADOS: Analisamos 146 pacientes, com média de idade de 44,5 anos e predomínio do sexo feminino. O principal sintoma foi dor abdominal. Tivemos ocorrência de segundo primário em 22 por cento dos casos e na imuno-histoquímica, 92 por cento foram positivos para CD117. A localização mais frequente foi estômago e predominou o grupo de alto risco. A cirurgia foi R0 (extenso) em 70 por cento e os principais sítios de metástases foram fígado e peritônio. A sobrevida global foi, respectivamente, em dois e cinco anos de 86 por cento e 59 por cento. Houve significante diferença entre a sobrevida global (p=0,29) do grupo de alto risco versus os demais. CONCLUSÃO: Os nossos pacientes apresentam-se principalmente sob forma de doença de alto risco com repercussão óbvia na sobrevida. O uso de Imatinib melhorou a sobrevida dos pacientes com doença metastática e recidivada. Devemos estudar seu uso no cenário de adjuvância e neoadjuvancia visando melhorar os índices do grupo de alto risco. A criação de centros referenciais é uma necessidade para o estudo de doenças pouco frequentes.

OBJECTIVE: To evaluate the treatment of GIST in INCA. METHODS: We conducted a retrospective analysis of all cases of GIST treated at INCA in the period from 1997 to 2009. RESULTS: We analyzed 146 patients with a mean age of 44.5 years and female predominance. The main symptom was abdominal pain. We observed the occurrence of a second primary tumor in 22 percent of cases and 92 percent of the immunohistochemistry exams were positive for CD117. The most frequent location was in the stomach and the high-risk group was predominant. Surgery was considered R0 (extensive) in 70 percent of the cases and the main sites of metastases were liver and peritoneum. Overall survival in two and five years was, respectively, 86 percent and 59 percent. There was a significant difference between overall survival (p = 0.29) of the high-risk group versus the other. CONCLUSION: Our patients presented mainly in the form of high-risk disease, with obvious impact on survival. The use of imatinib improved survival of patients with recurrent and metastatic disease. We should study its use in the setting of adjuvant and neoadjuvant therapy to improve results of the high risk group. The creation of reference centers is a need for the study of rare diseases.

Gastrointestinal stromal tumor: analysis of 146 cases of the center of reference of the National Cancer Institute--INCA.

OBJECTIVE: To evaluate the treatment of GIST in INCA. METHODS: We conducted a retrospective analysis of all cases of GIST treated at INCA in the period from 1997 to 2009. RESULTS: We analyzed 146 patients with a mean age of 44.5 years and female predominance. The main symptom was abdominal pain. We observed the occurrence of a second primary tumor in 22% of cases and 92% of the immunohistochemistry exams were positive for CD117. The most frequent location was in the stomach and the high-risk group was predominant. Surgery was considered R0 (extensive) in 70% of the cases and the main sites of metastases were liver and peritoneum. Overall survival in two and five years was, respectively, 86% and 59%. There was a significant difference between overall survival (p = 0.29) of the high-risk group versus the other. CONCLUSION: Our patients presented mainly in the form of high-risk disease, with obvious impact on survival. The use of imatinib improved survival of patients with recurrent and metastatic disease. We should study its use in the setting of adjuvant and neoadjuvant therapy to improve results of the high risk group. The creation of reference centers is a need for the study of rare diseases.

Colorectal GISTs: from presentation to survival. An analysis of 13 cases.

This papers is a retrospective analysis of all cases of colorectal GIST treated at our institution. Considering the increased interest in this pathology, in 2008, we recently established a unit supported by Novartis in our department to research and treat GIST. Since then, there was a dramatic increase in the referral of this type of tumor to our center. Before initiating our research group, we had the permission of the ethics committee and the medical directors to study and publish the analysis of our cases. Now, we have a cohort of 98 patients treated during the last 10 years and from that, we selected all cases of Colorectal GIST's. They numbered 13 cases. We performed an analysis of these cases from the presentation to the results of treatment.

Occurrence of other tumors in patients with GIST.

OBJECTIVE: Evaluate the presence of other tumors in cohort of patients with GIST treated at a cancer treatment referral center - INCA. METHODS: We reviewed the medical records of patients diagnosed with GIST who were treated at INCA between 1998 and 2008. Immunohistological diagnosis was confirmed by a pathologist specialized in sarcomas. Patients presenting second non-GIST tumors were identified. Age, sex, tumor location, risk groups (according to the National Institutes of Health criteria), characteristics of non-GIST tumors and treatment results were analyzed. RESULTS: Among the 101 patients diagnosed with GIST who were evaluated during the study period, 14 (13.8%) had other non-GIST tumors, 9 females (64.3%), with a median age of 68 years (10-79 years). The stomach was the location of GISTs in 8 cases (57.1%), followed by the small bowel in 4 cases (28.5%), colon and mesentery with 1 case (7.1%) each. The mean size of lesions was 4.79 cm (0.3-15 cm), with malignant potential low/very low in 7 cases (50%), intermediate in 5 cases (35.7%) and high in 2 cases (14.3%). The diagnosis of GIST was incidental in 6 cases and in one case the non-GIST tumor was incidental. The non-GIST tumors were most frequent in the stomach (adenocarcinoma), in 4 cases (28.5%) and colon/rectum (adenocarcinoma) in 4 other cases. The other sites involved were breast (ductal carcinoma), kidney (clear cell carcinoma), prostate (adenocarcinoma), endometrium (adenocarcinoma), ovary (adenocarcinoma) and adrenal (neuroblastoma), with one case each. The tumors were synchronous in 7 cases (50%). With a median follow-up after GIST resection of 41 months (2-87 months), 9 patients were alive without evidence of disease, 2 died due to GIST, 2 died due to non-GIST tumors and the remaining patient died due to postoperative complications. CONCLUSIONS: We discovered a 13.8% incidence of non-GIST tumors in a series of 101 GIST cases under our care. This association should always be considered in the management of patients with GIST.

Prognostic relevance of KIT and PDGFRA mutations in gastrointestinal stromal tumors.

BACKGROUND: Prediction of biological behavior is crucial for selection of new therapeutic modalities in GIST. Here, we aimed to assess whether KIT and PDGFRA mutations have survival impact in gastrointestinal stromal tumors (GIST). PATIENTS AND METHODS: Fifty-five Brazilian patients with completely resected GIST were examined for KIT and PDGFRA mutations. The 5-year disease-free survival (DFS) was analyzed. RESULTS: KIT and PDGFRA mutations were identified in 74.5% and 7.3% of patients, respectively. The 5-year DFS rate for all patients was 52.8%. The 5-year DFS rate was lower in patients with tumors having in-frame deletions or concomitant in-frame deletions and insertions affecting codons 557-558 than in patients with tumors having other exon 11 KIT mutations (p=0.023). Conversely, when the patients with concomitant deletion-insertion mutations affecting codons 557-558 were excluded from the analysis, deletions involving codons 557-558 had no influence on 5-year DFS rates. CONCLUSION: Our findings indicate that a specific KIT mutation may be associated with unfavorable behavior in GIST. This finding may have implications on selecting patients for adjuvant therapy.

Influence of sentinel lymph node tumor burden on survival in melanoma.

BACKGROUND: Completion lymph node dissection (CLND) is the standard procedure for patients with positive sentinel lymph nodes (SLN). With extensive pathological workup, increased numbers of small metastatic deposits are detected in SLN. This study evaluated the prognostic significance of SLN metastatic deposits < or = 0.2 mm in patients treated in a referral cancer center in Brazil. METHODS: Patients with stage I/II melanoma, consecutively submitted to a SLN procedure by the same surgeon from 2000 to 2006, were evaluated. All positive SLN and randomly selected negative cases were reviewed by two pathologists. Different prognostic factors and SLN tumor burden were recorded. Additional positive non-SLN after CLND, and disease outcome were evaluated. RESULTS: Of 381 patients who underwent SLN biopsy, 103 (27%) were positive. The mean/median Breslow tumor thickness in the overall group was 3.4/2.0 mm and in the SLN positive patients was 5.72/4.0 mm. Among these patients, 48 (47%) had metastatic deposits >2 mm (macrometastasis), 49 (47%) had metastatic deposits < or =2 mm but >0.2 mm (micrometastasis), and 6 (6%) had metastatic deposits < or =0.2 mm (submicrometastasis). Additional positive non-SLN were detected in 29% of patients with macrometastasis, in 25% of patients with micrometastasis, and in 0% of patients with submicrometastases. At median follow-up of 35 months, the estimated 3-year overall survival was 92% for negative SLN, 64% for micrometastases, 53% for macrometastases, and 100% for submicrometastases (P < 0.001). CONCLUSION: In the present study, patients with SLN metastatic deposits < or =0.2 mm had no additional positive non-SLNs, and no recurrences or deaths were recorded, suggesting that their prognosis is equivalent to that of patients with negative SLN.

Differences in the expression pattern of P-glycoprotein and MRP1 in low-grade and high-grade gliomas.

Multidrug resistance in gliomas is the major challenges in the clinical setting. We investigated the expression of P-glycoprotein (Pgp) and multidrug resistance-related protein 1 (MRP1) in 50 gliomas using immunohistochemistry. Compared to Pgp, MRP1 positivity was observed in highest percentage of gliomas grade IV samples (p = 0.008). Unlike MRP1 expression observed in high-grade, gliomas grade II exhibited a greater number of Pgp positive samples as compared to grades III and IV (p = 0.026). Our results suggest that the difference between the histological grade gliomas regarding MRP1 and Pgp expression must have implications in the choice of chemotherapeutic protocols.

What is the prognostic significance of metastatic lymph nodes in GIST?

BACKGROUND/AIMS: So many variables have been identified as prognostic factors influencing survival after curative resection in gastrointestinal stromal tumors (GIST), but the role of lymph node metastasis remains uncertain. METHODOLOGY: Twenty-nine patients with c-Kit positive gastric GIST who underwent surgical resection at the Brazilian National Cancer Institute between 1983 and 2004 were reviewed retrospectively. The prognostic significance of lymph node metastasis was investigated. The endpoints were overall survival and disease free survival. RESULTS: The median follow-up was 35 months. The 5-years estimate survival rate was 53%. Three patients presented lymph node metastasis and developed recurrence disease. Univariate analysis for overall survival identified the size >13.5cm (p = 0.01) and recurrence (p = 0.03) as prognostic factors. Size > 13.5cm and recurrence were independent factors (p = 0.01 and p = 0.03, respectively) in the multivariate analysis. Univariate analysis for disease free survival identified the size > 13.5cm (p = 0.04) and the grade (p = 0.04) as prognostic factors but, only the size > 13.5cm was an independent factor in the multivariate analysis. Lymph node metastasis had no prognostic significance for overall and disease free survival (p = 0.65 and p = 0.57, respectively). CONCLUSIONS: GIST lymph node metastasis was not related to poor survival in this study, but more studies are needed to identify the real incidence and the proper role of the GIST metastatic nodal disease.

Spatially variant apodization for squinted synthetic aperture radar images.

Spatially variant apodization (SVA) is a nonlinear sidelobe reduction technique that improves sidelobe level and preserves resolution at the same time. This method implements a bidimensional finite impulse response filter with adaptive taps depending on image information. Some papers that have been previously published analyze SVA at the Nyquist rate or at higher rates focused on strip synthetic aperture radar (SAR). This paper shows that traditional SVA techniques are useless when the sensor operates with a squint angle. The reasons for this behaviour are analyzed, and a new implementation that largely improves the results is presented. The algorithm is applied to simulated SAR images in order to demonstrate the good quality achieved along with efficient computation.