Pedro Aleixo

Publications (3) View all

• Article: Generation and characterization of new HER2 monoclonal antibodies.

  Flávia Aleixo Vasconcellos, Pedro Bandeira Aleixo, Simone Cardozo Stone, Fabricio Rochedo Conceição, Odir Antônio Dellagostin, José Antonio Guimarães Aleixo
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  ABSTRACT: Antibodies are among the most commonly used research and diagnostic tools. Antibody type and clonality are important in any assay as they can influence epitope detection. HER2 oncoprotein is overexpressed or undergoes gene amplification in approximately 30% of invasive breast carcinomas and 20% of gastric adenocarcinomas. Overexpression of HER2 is primarily detected by immunohistochemistry (IHC) on neoplastic tissue sections. We produced five murine hybridoma clones secreting monoclonal antibodies (MAbs) against HER2 protein. For hybridoma production, spleen cells from BALB/c mice immunized with a recombinant fragment of the extracellular portion of HER2 (rHER2) were fused to SP2/O-Ag14 cells, selected in HAT medium and screened by indirect ELISA. MAbs secreted were characterized according to isotypes, functional affinity constants, reaction with the native protein in MCF-7 cells by indirect immunofluorescence and in tissue sections from HER2 positive breast cancer specimens by IHC. Two MAbs were IgG2b and three were IgG1, and their affinity constants ranged from 6×10(7) to 1×10(9)M(-1). All MAbs reacted with the native protein and two stained strongly the membrane of neoplastic cells overexpressing HER2. These two MAbs could be useful in assaying HER2 overexpression in human tissues for research and possibly diagnostic purposes after a proper large-scale validation study.
  Acta histochemica 08/2012; · 1.23 Impact Factor
• Article: Can MDM2 and CDK4 make the diagnosis of well differentiated/dedifferentiated liposarcoma? An immunohistochemical study on 129 soft tissue tumours.

  P B Aleixo, A A Hartmann, I C Menezes, R T Meurer, A M Oliveira
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  ABSTRACT: Well differentiated liposarcomas (WDLPS) and dedifferentiated liposarcomas (DDLPS) have been shown to have supernumerary chromosomes with amplified sequences of the MDM2 and CDK4 genes. MDM2 and CDK4 protein overexpression have also been identified in these tumours. To investigate whether immunohistochemistry (IHC) for MDM2 and CDK4 can be used to diagnose WDLPS and DDLPS. IHC for MDM2/CDK4 was carried out on a series of 129 paraffin-embedded lipomatous and non-lipomatous soft tissue tumours. The cases were divided into four groups: WDLPS (n = 19), DDLPS (n = 10), benign adipocytic tumours (BAT) (n = 17), and other mesenquimal tumours (OMT) (n = 83). IHC results were compared in each group and the diagnostic efficacy of the test in identifying WDLPS and DDLPS among the other soft tissue tumours was determined. A percentage of tumour cell positivity was evaluated to better characterise the pattern of tumour immunostaining. Sensitivity and specificity of positive MDM2 and CDK4 immunostainings to identify WDLPS among BAT was 100% and 58.8%, and 68.4% and 88.2%, respectively. When distinguishing DDLPS from OMT, sensitivity and specificity of MDM2 and CDK4 were 90% and 65%, and 70% and 96.3%, respectively. The highest specificity was achieved when a case was considered positive with strong and diffuse immunoreactivity in more than 30% of the neoplastic cells (94.1% and 100%, and 77.1% and 98.8%, respectively). Detection of MDM2/CDK4 protein overexpression by IHC can be used by pathologists to diagnose WDLPS and DDLPS. Considering a strong and diffuse immunostaining pattern in most of the neoplastic cells achieves the best results in identifying these tumours.
  Journal of clinical pathology 12/2009; 62(12):1127-35. · 2.43 Impact Factor
• Article: Primary meningeal Burkitt-type lymphoma presenting as the first clinical manifestation of acquired immunodeficiency syndrome.

  Pedro Luís Gobbato, Arthur de Azambuja Pereira Filho, Gustavo de David, Mário de Barros Faria, Felipe de David, Pedro Bandeira Aleixo, Marinez Bizarro Barra, Nelson Pires Ferreira
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  ABSTRACT: The purpose of this study is to report a rare case of primary meningeal high grade Burkitt-type lymphoma presenting as the first clinical manifestation of acquired immunodeficiency syndrome. A 38-year-old Caucasian man, with a negative past medical history, sought treatment after experiencing global headache for five days. CT-Scan revealed a right front-temporo-parietal hyperdense subdural expansive mass. A craniotomy was performed and a hard white subdural was microsurgically dissected. Some hours after the surgery, the patient developed hemispheric cerebral edema and intracranial hypertension syndrome. Decompressive craniotomy was performed and the patient had an excellent recovery. Screening blood tests diagnosed human immunodeficiency virus infection. Further investigation ruled out systemic diseases. Eleven days after the initial surgery, the patient developed an acute respiratory failure and sepsis, dying on that day. Pathological studies diagnosed Burkitt-type lymphoma.
  Arquivos de Neuro-Psiquiatria 07/2006; 64(2B):511-5. · 0.72 Impact Factor