Publications by authors named "Margarita Matias-Florentino"

Lung adenocarcinoma is the most prevalent form of lung cancer, and drug resistance poses a significant obstacle in its treatment. This study aimed to investigate the overexpression of long non-coding RNAs (lncRNAs) as a mechanism that promotes intrinsic resistance in tumor cells from the onset of treatment. Drug-tolerant persister (DTP) cells are a subset of cancer cells that survive and proliferate after exposure to therapeutic drugs, making them an essential object of study in cancer treatment.

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Article Synopsis
  • The study emphasizes the need for flexible modeling approaches, specifically random-effects regression, to better understand the dynamics of infectious diseases such as HIV in evolving host populations.
  • By analyzing plasma viral load (pVL) data from 7,325 ART-naïve HIV patients in Mexico City between 2019 and 2021, the research reveals significant functional changes over time that a fixed-effects model couldn't fully capture.
  • The findings indicate a stronger negative correlation between pVL and CpG content in the HIV pol gene, suggesting that changes in the immune environment may influence viral load dynamics, highlighting the importance of molecular factors in disease progression.
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Background: SARS-CoV-2 infections have a wide spectrum of clinical manifestations whose causes are not completely understood. Some human conditions predispose to severe outcome, like old age or the presence of comorbidities, but many other facets, including coinfections with other viruses, remain poorly characterized.

Methods: In this study, the eukaryotic fraction of the respiratory virome of 120 COVID-19 patients was characterized through whole metagenomic sequencing.

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Coronavirus disease 2019 (COVID-19) vaccines effectively protect against severe disease and death. However, the impact of the vaccine used, viral variants, and host factors on disease severity remain poorly understood. This work aimed to compare COVID-19 clinical presentations and outcomes in vaccinated and unvaccinated patients in Mexico City.

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Evolutionary analyses of viral sequences can provide insights into transmission dynamics, which in turn can optimize prevention interventions. Here, we characterized the dynamics of HIV transmission within the Mexico City metropolitan area. HIV sequences from persons recently diagnosed at the largest HIV clinic in Mexico City (between 2016 and 2021) were annotated with demographic/geographic metadata.

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In this study, we analyzed the sequences of SARS-CoV-2 isolates of the Delta variant in Mexico, which has completely replaced other previously circulating variants in the country due to its transmission advantage. Among all the Delta sublineages that were detected, 81.5 % were classified as AY.

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During the coronavirus disease 2019 (COVID-19) pandemic, the emergence and rapid increase of the B.1.1.

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Article Synopsis
  • COVID-19, caused by the SARS-CoV-2 virus, presents a range of symptoms, from no symptoms to severe illness or death, with age and pre-existing conditions being key factors in severity.
  • A study in Mexico analyzed 57 complete SARS-CoV-2 genomes from patients under 60 without pre-existing conditions to explore relationships between viral genetics and disease severity.
  • The research found greater genomic diversity in the viruses compared to earlier strains and identified numerous mutations, but did not link specific mutations to disease outcomes, suggesting that severity is more influenced by patient genetics and demographics.
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Significant advances have been made recently in the development of targeted therapy for lung adenocarcinoma. However, platinum-based chemotherapy remains as the cornerstone in the treatment of this neoplasm. This is the treatment option for adenocarcinomas without gain-of-function mutations or tumors that have developed resistance to targeted therapy.

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In response to increasing pretreatment drug resistance (PDR), Mexico changed its national antiretroviral treatment (ART) policy, recommending and procuring second-generation integrase strand-transfer inhibitor (INSTI)-based regimens as preferred first-line options since 2019. We present a four-year observational study describing PDR trends across 2017-2020 at the largest HIV diagnosis and primary care center in Mexico City. A total of 6688 baseline protease-reverse transcriptase and 6709 integrase sequences were included.

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Unlabelled: Triple-negative breast cancer (TNBC) is an aggressive and heterogeneous disease. Seven subtypes have been described based on gene expression patterns. Herein, we characterized the tumor biology and clinical behavior of the immunomodulatory (IM) subtype.

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During the first year of the SARS-CoV-2 pandemic in Mexico, more than two million people were infected. In this study, we analyzed full genome sequences from 27 February 2020 to 28 February 2021 to characterize the geographical and temporal distribution of SARS-CoV-2 lineages and identify the most common circulating lineages during this period. We defined six different geographical regions with particular dynamics of lineage circulation.

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Introduction: Molecular surveillance systems could provide public health benefits to focus strategies to improve the HIV care continuum. Here, we infer the HIV genetic network of Mexico City in 2020, and identify actively growing clusters that could represent relevant targets for intervention.

Methods: All new diagnoses, referrals from other institutions, as well as persons returning to care, enrolling at the largest HIV clinic in Mexico City were invited to participate in the study.

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Article Synopsis
  • The COVID-19 pandemic has resulted in over three million deaths, highlighting the need to understand the disease's pathology and factors leading to severe outcomes.
  • A study examined the respiratory microbiota of COVID-19 patients compared to healthy individuals and patients with non-COVID-19 pneumonia, revealing significant differences in microbial composition and diversity.
  • Results indicated that increased dysbiosis and loss of microbial complexity in patients with COVID-19 are linked to worse clinical outcomes, suggesting the respiratory microbiota may influence disease severity.
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Article Synopsis
  • * Researchers identified a new variant called B.1.1.519, which has specific mutations (T478K, P681H, T732A) in its spike protein.
  • * This new variant quickly outperformed existing variants in Mexico, becoming the dominant strain in the first quarter of 2021.
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Next-generation sequencing (NGS) is increasingly used for HIV-1 drug resistance genotyping. NGS methods have the potential for a more sensitive detection of low-abundance variants (LAV) compared to standard Sanger sequencing (SS) methods. A standardized threshold for reporting LAV that generates data comparable to those derived from SS is needed to allow for the comparability of data from laboratories using NGS and SS.

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Objective: Pretreatment HIV-drug resistance (PDR, HIVDR) to non-nucleoside reverse transcriptase inhibitors (NNRTIs) is increasing globally. NNRTIs continue to be used as first-line antiretroviral therapy (ART) in some communities due to the cost of dolutegravir-based ART or dolutegravir-associated adverse events. A simplified version of the oligonucleotide ligation assay (OLA) - 'OLA-Simple' - is a low-cost, near point-of-care assay that provides ready-to-use lyophilized reagents and reports HIVDR mutations as colored lines on lateral flow strips.

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Background: Pretreatment HIV drug resistance (HIVDR) to NNRTIs has consistently increased in Mexico City during the last decade.

Objectives: To infer the HIV genetic transmission network in Mexico City to describe the dynamics of the local HIV epidemic and spread of HIVDR.

Patients And Methods: HIV pol sequences were obtained by next-generation sequencing from 2447 individuals before initiation of ART at the largest HIV clinic in Mexico City (April 2016 to June 2018).

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Background: Persistence of latent, replication-competent provirus in CD4 T cells of human immunodeficiency virus (HIV)-infected individuals on antiretroviral treatment (ART) is the main obstacle for virus eradication. Methylation of the proviral 5' long terminal repeat (LTR) promoter region has been proposed as a possible mechanism contributing to HIV latency; however, conflicting observations exist regarding its relevance. We assessed 5'-LTR methylation profiles in total CD4 T cells from blood of 12 participants on short-term ART (30 months) followed up for 2 years, and a cross-sectional group of participants with long-term ART (6-15 years), using next generation sequencing.

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Background: Increasing HIV pre-treatment drug resistance (PDR) levels have been observed in regions with increasing antiretroviral treatment (ART) coverage. However, data is lacking for several low/middle-income countries. We present the first PDR survey in Nicaragua since ART introduction in the country in 2003.

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Background: WHO has developed a global HIV-drug resistance surveillance strategy, including assessment of pretreatment HIV-drug resistance. We aimed to do a nationally representative survey of pretreatment HIV-drug resistance in Mexico using WHO-recommended methods.

Methods: Among 161 Ministry of Health antiretroviral therapy (ART) clinics in Mexico, the largest, including 90% of ART initiators within the Ministry of Health (66 in total), were eligible for the survey.

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Objective: The purpose of this study was to determine the molecular basis of retinitis pigmentosa (RP) in a 4 affected sib-family segregating this retinal phenotype.

Methods: Affected sibs underwent complete ophthalmologic examination including funduscopic inspection, electroretinogram, fluorescein angiography, visual field measurement, and optical coherence tomography. Both parents were deceased after their sixties and were reported with no visual handicap.

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Autosomal recessive retinitis pigmentosa (RP), a heterogeneous group of degenerations of the retina, can be due to mutations in the MFRP (membrane-type frizzled-related protein) gene. A patient with RP with MFRP mutations, one of which is novel and the first splice site mutation reported, was characterized by noninvasive retinal and visual studies. The phenotype, albeit complex, suggested that this retinal degeneration may be a candidate for gene-based therapy.

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Objective: Autosomal dominant (AD) inheritance accounts for 15-20% of retinitis pigmentosa (RP) familial cases. The characterization of AD RP-related mutations remains essential because it provides both accurate diagnosis and clinically important prognostic information. Rhodopsin (RHO) and peripherin/RDS are the two most common mutated genes in AD RP in several series.

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Purpose: The present work documents an outbreak of epidemic keratoconjunctivitis among ophthalmology residents, its influence in the presentation of the community cases, the use of molecular techniques for its diagnosis, and the implementation of successful control measures for its containment.

Methods: Isolation of the etiologic agent was achieved using cultured African green monkey kidney epithelial cells (VERO). Through molecular tests, such as polymerase chain reaction (PCR) and DNA sequencing, the genotype of the isolated virus was identified.

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