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1.
Cell Biosci ; 12(1): 162, 2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36180897

RESUMO

BACKGROUND: Immune checkpoints are a set of costimulatory and inhibitory molecules that maintain self-tolerance and regulate immune homeostasis. The expression of immune checkpoints on T cells in malignancy, chronic inflammation, and neurodegenerative diseases has gained increasing attention. RESULTS: To characterize immune checkpoints in neurodegenerative diseases, we aimed to examine the expression of the immune checkpoint PD-1/PD-L1 in peripheral T cells in different Alzheimer's disease (AD) patients. To achieve this aim, sixteen AD patients and sixteen age-matched healthy volunteers were enrolled to analyze their CD3+ T cells, CD3+CD56+ (neural cell adhesion molecule, NCAM) T cells, CD4+/CD8+ T cells, and CD4+/CD8+CD25+ (interleukin-2 receptor alpha, IL-2RA) T cells in this study. The expression of PD-1 on T cells was similar between the AD patients and healthy volunteers, but increased expression of PD-L1 on CD3+CD56+ T cells (natural killer T cells, NKT-like), CD4+ T cells (helper T cells, Th), CD4+CD25+ T cells, and CD8+ T cells (cytotoxic T lymphocytes, CTL) was detected in the AD patients. In addition, we found negative correlations between the AD patients' cognitive performance and both CD8+ T cells and CD8+CD25+ T cells. To identify CD8+ T-cell phenotypic and functional characteristic differences between the healthy volunteers and AD patients in different stages, a machine learning algorithm, t-distributed stochastic neighbor embedding (t-SNE), was implemented. Using t-SNE enabled the above high-dimensional data to be visualized and better analyzed. The t-SNE analysis demonstrated that the cellular sizes and densities of PD-1/PD-L1 on CD8+ T cells differed among the healthy, mild AD, and moderate AD subjects. CONCLUSIONS: Our results suggest that changes in PD-1/PD-L1-expressing T cells in AD patients' peripheral blood could be a potential biomarker for monitoring disease and shed light on the AD disease mechanism. Moreover, these findings indicate that PD-1/PD-L1 blockade treatment could be a novel choice to slow AD disease deterioration.

2.
Methods Mol Biol ; 2111: 141-151, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31933205

RESUMO

CD8+ T cells constitute an essential component of the adaptive immune system. They are activated through T cell receptor (TCR) recognizing antigenic peptides presented by MHC class I molecules expressed by antigen-presenting cells, such as dendritic cells (DCs). Harvesting a large number of activated, antigen-specific human CD8+ T cells for functional studies has been a laborious task for immunologists, largely because of the variables associated with DC preparations. Here we describe a robust, cost-effective DC-free antigen-presenting system capable of generating a large number of antigen-specific CD8+ T cells in vitro.


Assuntos
Linfócitos T CD8-Positivos/metabolismo , Antígenos de Histocompatibilidade Classe I/genética , Microglobulina beta-2/genética , Apresentação de Antígeno , Células Cultivadas , Técnicas de Cocultura , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Ativação Linfocitária , Proteínas Recombinantes/metabolismo , Microglobulina beta-2/metabolismo
3.
Cancers (Basel) ; 11(9)2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31480804

RESUMO

The unsatisfactory real-world efficacy of the hypomethylating agent azacitidine in treating myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) has prompted us to investigate the hematological adverse events and host variables that may compromise the use of this epigenetic drug. Using the zebrafish, we found that azacitidine destroyed their myeloid precursors and impaired myeloid function by inhibiting antigen processing, allogeneic response and phagocytic activity, resulting in increased susceptibility to infection even by the normal flora E. coli. In addition, iron overload, a MDS-associated condition following repeated transfusions, exacerbated bacterial infection especially by V. vulnificus with known iron dependence. Furthermore, we show that the tp53M214K mutant zebrafish survived longer than the wild-type (WT) when challenged with bacteria following azacitidine treatment. This was attributed to the mutant's hematopoietic cells rather than its general genetic background, since the WT animals reconstituted with the tp53M214K mutant kidney marrow became more resistant to bacterial infection following treatment with azacitidine. The clinical relevance of our findings was indicated by a MDS case with severe azacitidine-induced bone marrow suppression and by the association of hyperferritinemia with bacteremia in azacitidine-treated patients, while tp53M214K-mediated resistance to azacitidine-induced myelosuppression may explain the survival advantage of malignant MDS and AML clones over their normal counterparts under azacitidine treatment. Together, we propose that myelosuppression, iron overload and TP53 mutations may represent the host variables that compromise the azacitidine efficacy.

5.
J Mol Graph Model ; 92: 236-242, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31404877

RESUMO

Molecular dynamics (MD) simulations were carried out to study the physical properties of graphene-oxide (GO) and polydimethylsiloxane (PDMS) interfacial systems. Simulations were performed for GO molecules dispersed into short-chain, long-chain, and long-chain and cross-linked PDMS polymers. Various structural properties, dipole moments and dielectric constants of the graphene-oxide molecules were calculated, which were correlated with the electron transport properties of the GO/PDMS system. The effects of polymer length and type of linkage on transport properties were also examined.


Assuntos
Transporte de Elétrons , Grafite/química , Simulação de Dinâmica Molecular , Nanocompostos/química , Algoritmos , Modelos Moleculares , Estrutura Molecular
6.
PLoS One ; 13(8): e0202224, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30096190

RESUMO

We evaluated the prognostic significance of immunologic inhibitory biomarkers in head and neck squamous cell carcinoma (HNSCC) patients undergoing definitive chemoradiotherapy (CRT). Thirty patients were prospectively enrolled. Plasma levels of soluble MHC class I polypeptide-related sequence A (sMICA) and transforming growth factor-ß1 (TGF-ß1) were measured before and 2 weeks after CRT. The median follow-up was 32.9 months (range: 12.4-40.6 months). The pre-treatment sMICA (p < 0.001) and TGF-ß1 (p < 0.001) levels were significantly increased in HNSCC patients, compared to healthy controls. In HNSCC patients, the median pre-CRT and post-CRT sMICA levels were 43.1 pg/mL and 65.3 pg/mL, respectively, while the median pre-CRT and post-CRT TGF-ß1 levels were 57.7 ng/mL and 36.0 ng/mL, respectively. After CRT, 19 patients (63.3%) exhibited persistently elevated sMICA, six patients (20.0%) exhibited persistently elevated TGF-ß1, and five patients (16.7%) exhibited persistently elevated sMICA and TGF-ß1. Patients with persistently elevated sMICA and TGF-ß1 after CRT experienced an earlier tumor progression (p = 0.030), and poor overall survival (p = 0.010). Our results suggest that HNSCC patients who exhibit persistently elevated sMICA and TGF-ß1 levels after CRT are at higher risk of tumor progression or death.


Assuntos
Biomarcadores Tumorais/sangue , Neoplasias de Cabeça e Pescoço/imunologia , Neoplasias de Cabeça e Pescoço/terapia , Antígenos de Histocompatibilidade Classe I/sangue , Carcinoma de Células Escamosas de Cabeça e Pescoço/imunologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/terapia , Fator de Crescimento Transformador beta1/sangue , Adulto , Idoso , Biomarcadores Tumorais/imunologia , Quimiorradioterapia , Progressão da Doença , Neoplasias de Cabeça e Pescoço/sangue , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Intervalo Livre de Progressão , Estudos Prospectivos , Solubilidade , Carcinoma de Células Escamosas de Cabeça e Pescoço/sangue
7.
Int J Mol Sci ; 19(2)2018 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-29443941

RESUMO

Anaplastic thyroid carcinoma (ATC) is almost universally fatal. Elevated keratin-8 (KRT8) protein expression is an established diagnostic cancer biomarker in several epithelial cancers (but not ATC). Several keratins, including KRT8, have been suggested to have a role in cell biology beyond that of structural cytoskeletal proteins. Here, we provide evidence that KRT8 plays a direct role in the growth of ATCs. Genomic and transcriptomic analysis of >5000 patients demonstrates that KRT8 mutation and copy number amplification are frequently evident in epithelial-derived cancers. Carcinomas arising from diverse tissues exhibit KRT8 mRNA and protein overexpression when compared to normal tissue levels. Similarly, in a panel of patient-derived ATC cell lines and patient tumors, KRT8 expression shows a similar pattern. sh-RNA-mediated KRT8 knockdown in these cell lines increases apoptosis, whereas forced overexpression of KRT8 confers resistance to apoptosis under peroxide-induced cell stress conditions. We further show that KRT8 protein binds to annexin A2, a protein known to mediate apoptosis as well as the redox pathway.


Assuntos
Biomarcadores Tumorais/genética , Carcinoma/metabolismo , Queratina-8/genética , Neoplasias da Glândula Tireoide/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Anexina A2/metabolismo , Apoptose , Biomarcadores Tumorais/metabolismo , Carcinoma/genética , Carcinoma/patologia , Linhagem Celular Tumoral , Feminino , Dosagem de Genes , Humanos , Queratina-8/metabolismo , Masculino , Pessoa de Meia-Idade , Mutação , Ligação Proteica , Neoplasias da Glândula Tireoide/genética , Neoplasias da Glândula Tireoide/patologia , Regulação para Cima
8.
J Immunol Res ; 2018: 8363265, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30648121

RESUMO

Limited information is currently available concerning HLA class I antigen abnormalities in sarcomatoid hepatocellular carcinoma (sHCC). Here, we have analyzed the growth characteristics and HLA class I antigen status of four sHCC cell lines (sHCC29, sHCC63, sHCC74, and SAR-HCV); the first three were newly established in this study. Among the four, sHCC29 showed the highest growth rate in vitro and tumorigenicity in NOD-SCID mice. Unlike sHCC74 and SAR-HCV, both sHCC29 and sHCC63 had no detectable surface HLA class I antigen expression, alongside undetected intracellular ß 2-microglobulin (ß 2m) and marked HLA class I heavy chain and selective antigen-processing machinery (APM) component downregulation. The loss of ß 2m in sHCC29 and sHCC63 was caused by a >49 kb deletion across the B2M locus, while their downregulation of APM components was transcriptional, reversible by IFN-γ only in several components. ß 2m was also undetected in the primary HCC lesions of the patients involved, indicating its in vivo relevance. We report for the first time HLA class I antigen loss with underlying B2M gene deficiency and APM defects in 50% (2 of 4) of the sHCC cell lines tested. These findings may have implications for a proper design of T cell immunotherapy for the treatment of sHCC patients.


Assuntos
Carcinoma de Células Renais/metabolismo , Antígenos HLA/metabolismo , Antígenos de Histocompatibilidade Classe I/metabolismo , Neoplasias Experimentais/metabolismo , Microglobulina beta-2/metabolismo , Adulto , Idoso , Animais , Apresentação de Antígeno/genética , Carcinoma de Células Renais/patologia , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Antígenos HLA/genética , Antígenos de Histocompatibilidade Classe I/genética , Humanos , Masculino , Camundongos , Camundongos SCID , Pessoa de Meia-Idade , Mutação/genética , Neoplasias Experimentais/patologia , Microglobulina beta-2/genética
9.
Biosens Bioelectron ; 77: 1008-15, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26547427

RESUMO

Charge impurities and polar molecules on the surface of dielectric substrates has long been a critical obstacle to using graphene for its niche applications that involve graphene's high mobility and high sensitivity nature. Self-assembled monolayers (SAMs) have been found to effectively reduce the impact of long-range scatterings induced by the external charges. Yet, demonstrations of scalable device applications using the SAMs technique remains missing due to the difficulties in the device fabrication arising from the strong surface tension of the modified dielectric environment. Here, we use patterned SAM arrays to build graphene electronic devices with transport channels confined on the modified areas. For high-mobility applications, both rigid and flexible radio-frequency graphene field-effect transistors (G-FETs) were demonstrated, with extrinsic cutoff frequency and maximum oscillation frequency enhanced by a factor of ~2 on SiO2/Si substrates. For high sensitivity applications, G-FETs were functionalized by monoclonal antibodies specific to cancer biomarker chondroitin sulfate proteoglycan 4, enabling its detection at a concentration of 0.01 fM, five orders of magnitude lower than that detectable by a conventional colorimetric assay. These devices can be very useful in the early diagnosis and monitoring of a malignant disease.


Assuntos
Anticorpos Monoclonais/química , Proteoglicanas de Sulfatos de Condroitina/análise , Condutometria/instrumentação , Grafite/química , Proteínas de Membrana/análise , Células Neoplásicas Circulantes/química , Transistores Eletrônicos , Biomarcadores Tumorais/análise , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Imunoensaio/instrumentação , Microquímica/instrumentação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
10.
J Biol Chem ; 290(44): 26562-75, 2015 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-26381407

RESUMO

Scant information is available about the molecular basis of multiple HLA class I antigen-processing machinery defects in malignant cells, although this information contributes to our understanding of the molecular immunoescape mechanisms utilized by tumor cells and may suggest strategies to counteract them. In the present study we reveal a combination of IFN-γ-irreversible structural and epigenetic defects in HLA class I antigen-processing machinery in a recurrent melanoma metastasis after immunotherapy. These defects include loss of tapasin and one HLA haplotype as well as selective silencing of HLA-A3 gene responsiveness to IFN-γ. Tapasin loss is caused by a germ-line frameshift mutation in exon 3 (TAPBP(684delA)) along with a somatic loss of the other gene copy. Selective silencing of HLA-A3 gene and its IFN-γ responsiveness is associated with promoter CpG methylation nearby site-α and TATA box, reversible after DNA methyltransferase 1 depletion. This treatment combined with tapasin reconstitution and IFN-γ stimulation restored the highest level of HLA class I expression and its ability to elicit cytotoxic T cell responses. These results represent a novel tumor immune evasion mechanism through impairing multiple components at various levels in the HLA class I antigen presentation pathway. These findings may suggest a rational design of combinatorial cancer immunotherapy harnessing DNA demethylation and IFN-γ response.


Assuntos
Apresentação de Antígeno , Regulação Neoplásica da Expressão Gênica/imunologia , Inativação Gênica/imunologia , Antígeno HLA-A3/imunologia , Imunoterapia , Melanoma/imunologia , Evasão Tumoral , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/patologia , Linhagem Celular Tumoral , Ilhas de CpG/imunologia , Metilação de DNA/genética , Metilação de DNA/imunologia , Mutação da Fase de Leitura , Antígeno HLA-A3/genética , Humanos , Interferon gama/genética , Interferon gama/imunologia , Melanoma/genética , Melanoma/patologia , Melanoma/terapia , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/imunologia , Recidiva Local de Neoplasia
11.
Oncotarget ; 6(4): 2148-63, 2015 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-25669982

RESUMO

Tylophorine compounds have been the focus of drug development for decades. Tylophorine derivatives exhibit anti-cancer activities but their cellular targets remain unknown. We used a biotinylated tylophorine derivative to probe for the interacting cellular target(s) of tylophorine. Tylophorine directly binds to caprin-1 and consequently enhances the recruitment of G3BP1, c-Myc mRNA, and cyclin D2 mRNA to form a ribonucleoprotein complex. Subsequently, this tylophorine targeted ribonucleoprotein complex is sequestered to the polysomal fractions and the protein expressions of the associated mRNA-transcripts are repressed. Caprin-1 depleted carcinoma cells become more resistant to tylophorine, associated with decreased formation of the ribonucleoprotein complex targeted by tylophorine. Consequently, tylophorine downregulates c-Myc and cyclins D1/D2, causing hypophosphorylation of Rb and suppression of both processing-body formation and the Warburg effect. Gene expression profiling and gain-of-c-Myc-function experiments also revealed that the downregulated c-Myc contributes to the anti-oncogenic effects of tylophorine compounds. Furthermore, the potent tylophorine derivative dibenzoquinoline-33b elicited a similar effect, as c-Myc protein levels were also decreased in xenograft tumors treated with dibenzoquinoline-33b. Thus, tylophorine compounds exert anti-cancer activity predominantly by targeting and sequestering the caprin-1 protein and c-Myc mRNA associated ribonucleoprotein complex.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Neoplasias/metabolismo , Proteínas Proto-Oncogênicas c-myb/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Alcaloides/química , Alcaloides/metabolismo , Alcaloides/farmacologia , Animais , Western Blotting , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular/genética , Linhagem Celular , Linhagem Celular Tumoral , Ciclina D2/genética , Ciclina D2/metabolismo , DNA Helicases , Células HEK293 , Células HeLa , Células Hep G2 , Humanos , Indolizinas/química , Indolizinas/metabolismo , Indolizinas/farmacologia , Células MCF-7 , Camundongos , Complexos Multiproteicos/genética , Complexos Multiproteicos/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/genética , Fenantrenos/química , Fenantrenos/metabolismo , Fenantrenos/farmacologia , Proteínas de Ligação a Poli-ADP-Ribose , Ligação Proteica , Proteínas Proto-Oncogênicas c-myb/genética , RNA Helicases , Interferência de RNA , Proteínas com Motivo de Reconhecimento de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismo , Carga Tumoral/efeitos dos fármacos , Carga Tumoral/genética , Células U937 , Ensaios Antitumorais Modelo de Xenoenxerto
12.
Biochem Biophys Res Commun ; 441(3): 618-23, 2013 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-24183726

RESUMO

Defective human leukocyte antigen (HLA) class I expression in malignant cells facilitates their escape from destruction by CD8(+) cytotoxic T lymphocytes. In this study, a post-translational mechanism of HLA class I abnormality that does not involve defects in the HLA subunits and antigen processing machinery components was identified and characterized. The marked HLA class I downregulation phenotype of a metastatic carcinoma cell line can be readily reversed by trypsin, suggesting a masking effect by serine protease-sensitive HLA class I-interacting factors. Co-immunoprecipitation, combined with LC-tandem mass spectrometry and immunoblotting identified these factors as cytokeratin (CK) 8 and its heterodimeric partners CK18 and CK19. Ectopic CK8/18 or CK8/19 expression in HEK293 cells resulted in surface CK8 expression with an HLA class I downregulation phenotype, while redirecting CK8/18 and CK8/19 to the endoplasmic reticulum (ER) had no such effect. This observation and the failure to constrain CK8/18 and CK8/19 membrane trafficking by an ER-Golgi transport inhibitor suggested an ER-independent route for CK8 access to HLA class I molecules. Monoclonal antibody mapping revealed a potential CK8 blockade of HLA class I-CD8 and -TCR contacts. These findings, along with the emerging role of cell surface CK8 in cancer metastasis, may imply a dual strategy for tumor cell survival in the host.


Assuntos
Carcinoma/secundário , Antígenos de Histocompatibilidade Classe I/imunologia , Queratina-8/imunologia , Metástase Linfática/imunologia , Evasão Tumoral , Sequência de Aminoácidos , Anticorpos Monoclonais , Linhagem Celular Tumoral , Células HEK293 , Humanos , Imunoprecipitação , Queratina-18 , Queratina-19 , Linfonodos/imunologia , Linfonodos/patologia , Dados de Sequência Molecular , Multimerização Proteica , Tripsina/imunologia
13.
Biochem Biophys Res Commun ; 440(1): 190-5, 2013 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-24055710

RESUMO

Class II transactivator (CIITA) plays a critical role in controlling major histocompatibility complex (MHC) class II gene expression. In this study, two novel alternatively spliced variants of human interferon (IFN)-γ-inducible CIITA, one missing exon 7 (CIITAΔE7), the other with TAG inserted at exon 4/5 junction (CIITA-TAG), were identified and characterized. Both variants are naturally occurring since they are present in primary cells. Unlike CIITA-TAG, CIITAΔE7 is expressed more abundantly in lung adenocarcinoma A549 cells than in the non-transformed counterpart BEAS-2B cells following IFN-γ stimulation. Transfection experiments showed that CIITAΔE7 induced a markedly lower level of surface HLA-DR, -DP, -DQ expression than CIITA-TAG in A549 cells but not in BEAS-2B cells, although both variants elicited similar amounts of total DR, DP, and DQ proteins. This differential effect was correlated with, in A549 cells, decreased expression of Ii and HLA-DM genes, along with increased expression of HLA-DO genes. Ii and HLA-DM are chaperons assisting in HLA class II assembly, while HLA-DO functions to inhibit endosomal peptide loading and HLA class II membrane transport. These findings raise the possibility that CIITAΔE7 interacts with unknown cancer-associated factors to selectively modulate genes involved in the assembly and transport of HLA class II molecules.


Assuntos
Adenocarcinoma/genética , Regulação Neoplásica da Expressão Gênica , Antígenos HLA-D/genética , Interferon gama/metabolismo , Neoplasias Pulmonares/genética , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Transativadores/genética , Transativadores/metabolismo , Adenocarcinoma/metabolismo , Adenocarcinoma de Pulmão , Animais , Sequência de Bases , Linhagem Celular , Linhagem Celular Tumoral , Células Cultivadas , Éxons , Deleção de Genes , Genes MHC da Classe II , Humanos , Neoplasias Pulmonares/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo
14.
J Virol ; 87(9): 4965-73, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23408634

RESUMO

Baculovirus (BV) is a promising gene therapy vector and typically requires readministration because BV mediates transient expression. However, how the prime-boost regimen triggers BV-specific adaptive responses and their impacts on BV readministration, transgene expression, and therapeutic/vaccine efficacy remain unknown. Here we unraveled that BV injection into BALB/c mice induced the production of BV-specific antibodies, including IgG1 and IgG2a, which could neutralize BV by antagonizing the envelope protein gp64 and impede BV-mediated transgene expression. Moreover, humans did not possess preexisting anti-BV antibodies. BV injection also elicited BV-specific Th1 and Th2 responses as well as CD4(+) and CD8(+) T cell responses. gp64 was a primary immunogen to activate the antibody and CD8(+) T cell response, with its peptide at positions 457 to 465 (peptide 457-465) being the major histocompatibility complex (MHC) class I epitope to stimulate CD8(+) T cell and cytotoxic responses. Nonetheless, a hybrid Sleeping Beauty-based BV enabled long-term expression for >1 year by a single injection, indicating that the T cell responses did not completely eradicate BV-transduced cells and implicating the potential of this hybrid BV vector for gene therapy. These data unveil that BV injection triggers adaptive immunity and benefit rational design of BV administration schemes for gene therapy and vaccination.


Assuntos
Imunidade Adaptativa , Baculoviridae/imunologia , Vetores Genéticos/imunologia , Transgenes , Animais , Baculoviridae/genética , Linfócitos T CD8-Positivos/imunologia , Linhagem Celular , Feminino , Terapia Genética , Vetores Genéticos/genética , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Células Th1/imunologia , Células Th2/imunologia
15.
Neural Netw ; 25(1): 57-69, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21802901

RESUMO

Based on the reduced SVM, we propose a multi-view algorithm, two-teachers-one-student, for semi-supervised learning. With RSVM, different from typical multi-view methods, reduced sets suggest different views in the represented kernel feature space rather than in the input space. No label information is necessary when we select reduced sets, and this makes applying RSVM to SSL possible. Our algorithm blends the concepts of co-training and consensus training. Through co-training, the classifiers generated by two views can "teach" the third classifier from the remaining view to learn, and this process is performed for each choice of teachers-student combination. By consensus training, predictions from more than one view can give us higher confidence for labeling unlabeled data. The results show that the proposed 2T1S achieves high cross-validation accuracy, even compared to the training with all the label information available.


Assuntos
Algoritmos , Aprendizagem , Estudantes , Ensino , Interpretação Estatística de Dados , Aprendizagem/fisiologia , Ensino/métodos
16.
Ultrasound Med Biol ; 35(12): 2055-68, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19828227

RESUMO

The Nakagami parameter associated with the Nakagami distribution estimated from ultrasonic backscattered signals reflects the scatterer concentration in a tissue. A nonfocused transducer does not allow tissue characterization based on the Nakagami parameter. This paper proposes a new method called the noise-assisted Nakagami parameter based on empirical mode decomposition of noisy backscattered echoes to allow quantification of the scatterer concentration based on data obtained using a nonfocused transducer. To explore the practical feasibility of the proposed method, the current study performed experiments on phantoms and measurements on rat livers in vitro with and without fibrosis induction. The results show that using a nonfocused transducer makes it possible to use the noise-assisted Nakagami parameter to classify phantoms with different scatterer concentrations and different stages of liver fibrosis in rats more accurately than when using techniques based on the echo intensity and the conventional Nakagami parameter. However, the conventional Nakagami parameter and the noise-assisted Nakagami parameter have different meanings: the former represents the statistics of signals backscattered from unresolvable scatterers, whereas the latter is associated with stronger resolvable scatterers or local inhomogeneity caused by scatterer aggregation.


Assuntos
Algoritmos , Interpretação de Imagem Assistida por Computador/métodos , Cirrose Hepática/diagnóstico por imagem , Fígado/diagnóstico por imagem , Ultrassonografia/métodos , Animais , Interpretação Estatística de Dados , Aumento da Imagem/métodos , Ratos , Ratos Wistar , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
17.
N Engl J Med ; 360(14): 1408-17, 2009 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-19339720

RESUMO

BACKGROUND: We investigated the efficacy of cetuximab plus irinotecan, fluorouracil, and leucovorin (FOLFIRI) as first-line treatment for metastatic colorectal cancer and sought associations between the mutation status of the KRAS gene in tumors and clinical response to cetuximab. METHODS: We randomly assigned patients with epidermal growth factor receptor-positive colorectal cancer with unresectable metastases to receive FOLFIRI either alone or in combination with cetuximab. The primary end point was progression-free survival. RESULTS: A total of 599 patients received cetuximab plus FOLFIRI, and 599 received FOLFIRI alone. The hazard ratio for progression-free survival in the cetuximab-FOLFIRI group as compared with the FOLFIRI group was 0.85 (95% confidence interval [CI], 0.72 to 0.99; P=0.048). There was no significant difference in the overall survival between the two treatment groups (hazard ratio, 0.93; 95% CI, 0.81 to 1.07; P=0.31). There was a significant interaction between treatment group and KRAS mutation status for tumor response (P=0.03) but not for progression-free survival (P=0.07) or overall survival (P=0.44). The hazard ratio for progression-free survival among patients with wild-type-KRAS tumors was 0.68 (95% CI, 0.50 to 0.94), in favor of the cetuximab-FOLFIRI group. The following grade 3 or 4 adverse events were more frequent with cetuximab plus FOLFIRI than with FOLFIRI alone: skin reactions (which were grade 3 only) (in 19.7% vs. 0.2% of patients, P<0.001), infusion-related reactions (in 2.5% vs. 0%, P<0.001), and diarrhea (in 15.7% vs. 10.5%, P=0.008). CONCLUSIONS: First-line treatment with cetuximab plus FOLFIRI, as compared with FOLFIRI alone, reduced the risk of progression of metastatic colorectal cancer. The benefit of cetuximab was limited to patients with KRAS wild-type tumors. (ClinicalTrials.gov number, NCT00154102.)


Assuntos
Anticorpos Monoclonais/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Receptores ErbB/antagonistas & inibidores , Genes ras , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais Humanizados , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Camptotecina/análogos & derivados , Camptotecina/uso terapêutico , Cetuximab , Neoplasias Colorretais/genética , Progressão da Doença , Feminino , Fluoruracila/uso terapêutico , Humanos , Estimativa de Kaplan-Meier , Leucovorina/uso terapêutico , Masculino , Pessoa de Meia-Idade , Mutação , Metástase Neoplásica/tratamento farmacológico , Adulto Jovem
18.
Cancer Immunol Immunother ; 58(3): 395-408, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18704411

RESUMO

In renal cell carcinoma (RCC), HLA class I downregulation has been found in about 40% of the lesions examined. Since only scanty information is available about the molecular basis of these defects, we have investigated the mechanism(s) underlying HLA class I antigen downregulation or loss in six RCC cell lines. Five of them express HLA class I antigens although at various levels; on the other hand, HLA class I antigens are not detectable on the remaining cell line, the RCC52 cell line, belonging to a sarcomatoid subtype, even following incubation with IFN-gamma. beta(2)-microglobulin (beta(2) m) was not detected in RCC52 cells. Surprisingly, RCC52 cells harbor two mutations in the beta ( 2 ) m genes in exon 1: a single G deletion (delG) in codon 6, which introduces a premature stop at codon 7, and a CT dinucleotide deletion (delCT), which leads to a premature stop at codon 55. Analysis of eight clonal sublines isolated from the RCC52 cell line showed that the two beta ( 2 ) m gene mutations are carried separately by RCC52 cell subpopulations. The delG/delCT double mutations were detected in two sublines with a fibroblast-like morphology, while the delCT mutation was detected in the remaining six sublines with an epithelial cell morphology. Furthermore, loss of heterozygosity (LOH) of the beta ( 2 ) m gene at STR D15S-209 was found only in the epithelioid subpopulation, indicating loss of one copy of chromosome 15. Immunostaining results of the tumor lesion from which the cell line RCC52 was originated were consistent with the phenotyping/molecular findings of the cultured cells. This is the first example of the coexistence of distinct beta ( 2 ) m defects in two different tumor subpopulations of a RCC, where loss of one copy of chromosome 15 occurs in one of the subpopulations with total HLA class I antigen loss.


Assuntos
Carcinoma/metabolismo , Regulação Neoplásica da Expressão Gênica , Genes MHC Classe I , Antígenos HLA/metabolismo , Neoplasias Renais/metabolismo , Mutação , Sarcoma/metabolismo , Microglobulina beta-2/genética , Microglobulina beta-2/metabolismo , Animais , Linhagem Celular Tumoral , Células Epiteliais/metabolismo , Humanos , Interferon gama/metabolismo , Perda de Heterozigosidade , Camundongos
19.
Ultrasonics ; 49(4-5): 413-8, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19056100

RESUMO

The threshold filter is a frequently used technique in ultrasound B-scan to reject the small echoes contributed from backscattering that blur the tissue interface and reduce the image contrast. Note that using the threshold based on one value would simultaneously destroy local waveform features of the reflection echoes with amplitudes larger than threshold value. To resolve this problem, we developed an adaptive threshold filter based on the noise-assisted empirical mode decomposition (EMD). Computer simulations at 7.5 MHz using a single-element transducer with a bandwidth of 60% and a pulselength of 0.5 micros were carried out to explore the feasibility of the algorithm. Image measurements on the carotid artery using a 7.5 MHz, 128 elements, 1D linear array transducer with the same characteristics as those in simulations were used to verify the performance of the algorithm in practice. Compared to the result from the conventional threshold technique, the adaptive threshold filter is able to successfully suppress the smaller backscattering signals without changing the local waveform features of the preserved significant echoes due to reflection.


Assuntos
Ultrassom , Algoritmos , Simulação por Computador , Filtração , Transdutores , Ultrassonografia
20.
Rev. argent. cancerol ; 37(1): 41-50, 2009. graf
Artigo em Espanhol | BINACIS | ID: bin-124636

RESUMO

Antecedentes: Se investigó la eficacia de cetuximab más irinotecan, fluorouracilo y leucovorina (FOLFIRI) como tratamiento metastásico y las asociaciones buscadas entre el estado de mutación del gen KRAS en tumores y la respuesta clínica a cetuximab. Métodos: Se asignaro en forma aleatoria pacientes con cáncer colorrectal con expresión positiva del receptor de factor de crecimiento epidérmico, con metástasis irresecables para recibir FOLFIRI, ya sea solo o en combinación con cetuximab. El criterio de valoración primario fue la supervivencia libre de progresión. Conclusión: El tratamiento de primera línea con cetuximab más FOLFIRI, comparado con FOLFIRI solo, redujo el riesgo de progresión del cáncer colorrectal metastásico. El beneficio de cetuximab resultó limitado para pacientes con tumores con KRAS no mutado.(AU)


Assuntos
Neoplasias Colorretais , Tratamento Farmacológico , Interpretação Estatística de Dados
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