Publications by authors named "Matias E Melendez"

Article Synopsis
  • Blood culture is a slow and often ineffective method for identifying pathogens in bloodstream infections, particularly concerning for pediatric oncology patients facing febrile neutropenia.
  • Two new High-Resolution Melting (HRM) assays were developed, showing excellent specificity and the ability to detect very low amounts of bacterial DNA, outperforming traditional blood culture methods.
  • The HRM assays demonstrated variable sensitivity in identifying pathogens from blood samples of pediatric cancer patients, indicating their potential as a quicker diagnostic tool for managing infections in this vulnerable group.
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Germline TP53 pathogenic variants can lead to a cancer susceptibility syndrome known as Li-Fraumeni (LFS). Variants affecting its activity can drive tumorigenesis altering p53 pathways and their identification is crucial for assessing individual risk. This study explored the functional impact of TP53 missense variants on its transcription factor activity.

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Viral respiratory infections represent a major threat to the population's health globally. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19 disease and in some cases the symptoms can be confused with Influenza disease caused by the Influenza A viruses. A simple, fast, and selective assay capable of identifying the etiological agent and differentiating the diseases is essential to provide the correct clinical management to the patient.

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Background: Epidermal growth factor receptor (EGFR) is frequently activated in head and neck squamous cell carcinoma (HNSCC) and serves as a valuable target for therapy. Despite the availability of the EGFR inhibitors Cetuximab, Afatinib, and Allitinib, there are limited predictive markers for their response. Understanding molecular aberrations in HNSCC could facilitate the identification of new strategies for patient clinical and biological classification, offering novel therapeutic avenues.

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Background: Gastrointestinal stromal tumors (GIST) represent a significant clinical challenge due to their metastatic potential and limited treatment options. Raf kinase inhibitor protein (RKIP), a suppressor of the MAPK signaling pathway, is downregulated in various cancers and acts as a metastasis suppressor. Our previous studies demonstrated low RKIP expression in GIST and its association with poor outcomes.

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Background: Metastatic lymph node involvement influences therapy decisions and serves as a prognostic indicator in oral squamous cell carcinoma (OSCC). However, many early-stage patients with clinically negative lymph nodes exhibit no metastasis upon surgical staging. This study aimed to identify differentially expressed miRNAs capable of distinguishing pathologically positive (pN+) from negative (pN0) nodes in OSCC patients without clinical evidence of lymph node metastases (cN0).

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Background: Breast and ovarian tumors with pathogenic variants in or genes are more sensitive to poly (ADP-ribose) polymerase inhibitors (PARPi) treatment than wildtype tumors. Pathogenic variants in non- homologous recombination repair genes (HRR) also concede sensitivity to PARPi treatment. participates in the Mre11--Nbn (MRN) complex of the HRR pathway and plays an important role in DNA repair.

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Low-cost, instrument-free colorimetric tests were developed to detect SARS-CoV-2 using plasmonic biosensors with Au nanoparticles functionalized with polyclonal antibodies (f-AuNPs). Intense color changes were noted with the naked eye owing to plasmon coupling when f-AuNPs form clusters on the virus, with high sensitivity and a detection limit of 0.28 PFU mL (PFU stands for plaque-forming units) in human saliva.

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Article Synopsis
  • The Barretos Cancer Hospital Animal Facility (BCHAF) in Brazil specializes in using animal models to advance cancer research.
  • The facility conducts experiments involving mutant strains of mice, xenograft models, and patient-derived xenografts (PDXs).
  • The research highlights both progress and challenges in creating these models to improve understanding of tumor biology and to identify potential cancer biomarkers for personalized treatment.
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Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) syndrome, characterized by germline pathogenic variants in mismatch repair (MMR)-related genes that lead to microsatellite instability. Patients who meet the clinical criteria for LS and MMR deficiency and without any identified germline pathogenic variants are frequently considered to have Lynch-like syndrome (LLS). These patients have a higher risk of CRC and extracolonic tumors, and little is known about their underlying genetic causes.

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Background: EGFR mutations are present in approximately 15−50% of non-small cell lung cancer (NSCLC), which are predictive of anti-EGFR therapies. At variance, NSCLC patients harboring KRAS mutations are resistant to those anti-EGFR approaches. Afatinib and allitinib are second-generation pan-EGFR drugs, yet no predictive biomarkers are known in the NSCLC context.

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Article Synopsis
  • A new immunosensor was created to detect the cancer biomarker p53 in cell lysates, using high sensitivity electrical impedance spectroscopy techniques.
  • The sensor was built on bacterial nanocellulose with a specific matrix of chitosan and chondroitin sulfate, achieving detection limits as low as 0.16 U/mL for p53.
  • To differentiate p53 samples from other substances, a supervised machine learning method was applied, utilizing decision trees to manage the complex data and enhance specificity.
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The diagnosis of cancer and other diseases using data from non-specific sensors - such as the electronic tongues (e-tongues) - is challenging owing to the lack of selectivity, in addition to the variability of biological samples. In this study, we demonstrate that impedance data obtained with an e-tongue in saliva samples can be used to diagnose cancer in the mouth. Data taken with a single-response microfluidic e-tongue applied to the saliva of 27 individuals were treated with multidimensional projection techniques and non-supervised and supervised machine learning algorithms.

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Familial colorectal cancer type X (FCCTX) is a heterogeneous colorectal cancer predisposition syndrome that, although displays a cancer pattern similar to Lynch syndrome, is mismatch repair proficient and does not exhibit microsatellite instability. Besides, its genetic etiology remains to be elucidated. In this study we performed germline exome sequencing of 39 cancer-affected patients from 34 families at risk for FCCTX.

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Down syndrome (DS) is the most common chromosomal disorder, resulting from the failure of normal chromosome 21 segregation. Studies have suggested that impairments within the one-carbon metabolic pathway can be of relevance for the global genome instability observed in mothers of individuals with DS. Based on the association between global DNA hypomethylation, genome instability, and impairments within the one-carbon metabolic pathway, the present study aimed to identify possible predictors, within the one-carbon metabolism, of global DNA methylation, measured by methylation patterns of LINE-1 and Alu repetitive sequences, in mothers of individuals with DS and mothers of individuals without the syndrome.

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Evaluate the biological action of valproic acid in the acetylation of histones and in the methylation of tumor suppressor genes via oral rinse in patients with a previous history of head and neck squamous cell carcinoma (HNSCC). Forty-two active or former smokers were included in this randomized, double-blind, placebo-controlled trial. Oral rinse samples were collected prior to treatment with valproic acid or placebo and after 90 days of treatment.

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The identification of molecular markers in negative surgical margins of oral squamous cell carcinoma (OSCC) might help in identifying residual molecular aberrations, and potentially improve the prediction of prognosis. We performed an Infinium MethylationEPIC BeadChip array on 32 negative surgical margins stratified based on the status of tumor recurrence in order to identify recurrence-specific aberrant DNA methylation (DNAme) markers. We identified 2512 recurrence-associated Differentially Methylated Positions (DMPs) and 392 Differentially Methylated Regions (DMRs) which were enriched in cell signaling and cancer-related pathways.

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Article Synopsis
  • - The study focused on discovering new genetic predisposition genes for breast and ovarian cancer by performing whole-exome sequencing on women at high risk who did not carry known mutations (non-BRCA1/2/TP53).
  • - Through various analyses, researchers identified several pathogenic variants in established cancer-related genes and found rare variants in DNA repair and other cancer-associated genes.
  • - A significant finding was the c.149T>G variant in the FAN1 gene, which was found in two families, one of which showed loss of heterozygosity in tumor tissue, highlighting important new genetic risks in hereditary breast and ovarian cancer.
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Article Synopsis
  • The paper discusses the creation of genosensors designed to detect a specific DNA sequence related to prostate cancer (PCA3), which could improve early diagnosis and treatment.
  • Various detection methods were used, with electrochemical impedance spectroscopy showing the highest sensitivity at a detection limit of 83 pM, surpassing other methods like cyclic voltammetry and UV-vis spectroscopy.
  • Machine learning was applied to analyze scanning electron microscopy images of the genosensors, achieving a remarkable classification accuracy of 99.9% for PCA3 detection, though identifying specific PCA3 concentrations showed lower accuracy, indicating a need for improved image analysis techniques.
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Background: Lack of complete genomic data of impedes molecular biology research focusing on biotechnological applications of venom gland components. Identification of full-length coding regions of genes is crucial for the correct molecular cloning design.

Methods: RNA was extracted from the venom gland of one adult female specimen of .

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A disposable electrochemical immunosensors is presented suitable to detect cancer biomarker p53 using screen-printed carbon electrodes modified with a layer-by-layer (LbL) matrix of carboxylated NiFeO nanoparticles and polyethyleneimine, onto which anti-p53 antibodies were adsorbed. Under optimized conditions, the immunosensors exhibited high surface coverage and high concentration of immobilized antibodies, which allowed for detection of p53 in a wide dynamic range from 1.0 to 10 × 10 pg mL, with a limit of detection of 5.

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Background: Oropharyngeal squamous cell carcinomas (OpSCCs) are commonly associated with high rates of treatment failure.

Objectives: To evaluate methylation-based markers in plasma from OpSCC patients as emerging tools for accurate/noninvasive follow-up.

Methods: Pretreatment formalin-fixed paraffin-embedded (FFPE) biopsies (n = 52) and paired plasma (n = 15) were tested for the methylation of CCNA1, DAPK, CDH8, and TIMP3 by droplet digital PCR (ddPCR).

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Electrochemical immunosensors have been developed to determine the carbohydrate antigen 19-9 (CA19-9). They are based on screen-printed carbon electrodes (SPCEs) coated with layer-by-layer (LbL) films of carbon black (CB) and polyelectrolytes. Owing to a suitable choice of LbL film architecture, the procedures for immobilization of anti-CA19-9 antibodies on the electrode surfaces were straightforward.

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This paper reports on biosensors made with a matrix of polylactic acid (PLA) fibers, which are suitable for immobilization of the anti-p53 active layer for detection of p53 biomarker. The PLA fibers were produced with solution blow spinning, a method that is advantageous for its simplicity and possibility to tune the fiber properties. For the biosensors, the optimized time to deposit the fibers was 60 s, with which detection of p53 could be achieved with the limit of detection of 11 pg/mL using electrical impedance spectroscopy.

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Tobacco- or human papillomavirus- driven oropharyngeal squamous cell carcinomas (OpSCC) represent distinct clinical, biological and epidemiological entities. The aim of this study was to identify genetic variants based on somatic alterations in OpSCC samples from an admixed population, and to test for association with clinical features. The entire coding region of 15 OpSCC driver genes was sequenced by next-generation sequencing in 51 OpSCC FFPE samples.

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