Publications by authors named "Mariano Gustavo Zalis"

Article Synopsis
  • The study explores challenges in lung cancer biomarker testing due to tissue inadequacy and operational issues, implementing a tailored molecular testing approach in Brazil.
  • From 1,272 lung cancer samples analyzed, a significant percentage were ineligible for testing due to insufficient tissue quality or quantity, with specific mutations and alterations being most commonly observed.
  • Results suggest that while non-NGS tests provided some diagnostic information, a substantial portion of patients could only access reduced molecular testing coverage, impacting the detection of actionable cancer drivers.
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Costs may hinder the implementation of BK polyomavirus (BKV)-DNAemia screening in resource-limited kidney transplant (KT) centers. We analyzed data from two studies to assess the performance and potential cost saving of a dual-step screening strategy based on the use of a preliminary qualitative semi-nested PCR (snPCR) assay followed by BKV-DNAemia quantification after KT. In the preliminary study, in which 130 samples from 33 KT recipients were screened for BKV-DNAemia, the estimated positive and negative predictive values of snPCR, as compared to quantitative PCR (qPCR), were 88% and 99%, respectively.

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Introduction: Mutations in the propeller domain of the Plasmodium falciparum kelch13 (k13) gene are associated with artemisinin resistance.

Methods: We developed a PCR protocol to sequence the pfk13 gene and determined its sequence in a batch of 50 samples collected from 2003 to 2016 in Brazil.

Results: We identified 1 K189T substitution located outside the propeller domain of the PfK13 protein in 36% of samples.

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To our knowledge, there are no published data on hepatitis C virus (HCV) genotypes in Angola. This study aimed at assessing the distribution of HCV genotypes in seropositive hemodialysis patients in Luanda. Among 51 HCV-positive subjects included, viremia was detected in 27 (53%).

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BKV and JCV belong to the Polyomaviridae family and are opportunistic agents associated with complications in immunocompromised individuals. Although a single screening assay for both viruses would be convenient, the diversity of BKV and JCV serotypes and genotypes is a methodological challenge. In this paper, we developed a PCR method able to detect and segregate BKV and JCV, despite these genetic discrepancies.

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Antimalarial interventions mostly rely upon drugs, as chloroquine. However, plasmodial strains resistant to many drugs are constantly reported, leading to an expansion of malaria cases. Novel approaches are required to circumvent the drug resistance issue.

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Introduction: In different parts of the world, mutations in the GJB2 gene are associated with nonsyndromic hearing loss, and the homozygous 35delG mutation (p.Gly12Valfs*2) is a major cause of hereditary hearing loss. However, the 35delG mutation is not equally prevalent across ethnicities, making it important to study other mutations, especially in multiethnic countries such as Brazil.

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Zoonotic malaria poses a unique problem for malaria control. Autochthonous cases of human malaria in the Atlantic Forest have recently been attributed to Plasmodium simium, a parasite that commonly infects non-human primates in this Brazilian biome. However, due to its close similarity at both the morphological and molecular level to Plasmodium vivax, the diagnosis of P.

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Background: Malaria was eliminated from southern and southeastern Brazil over 50 years ago. However, an increasing number of autochthonous episodes attributed to Plasmodium vivax have recently been reported from the Atlantic Forest region of Rio de Janeiro state. As the P vivax-like non-human primate malaria parasite species Plasmodium simium is locally enzootic, we performed a molecular epidemiological investigation to determine whether zoonotic malaria transmission is occurring.

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In this cross-sectional study, 207 hepatitis B surface antigen (HBsAg)-negative kidney transplant recipients were evaluated based on demographic and epidemiological data and on the levels of serological markers of hepatitis B virus (HBV) and hepatitis C virus infection and liver enzymes. Patients with HBV or human immunodeficiency virus infection were excluded. Sera were analysed for the presence of HBV-DNA.

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Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine cancer, with approximately 80% of cases associated with Merkel cell polyomavirus (MCPyV). The lack of information concerning its occurrence in non-MCC immunosuppressed populations led to the investigation of MCPyV DNA in saliva and oral biopsies from 60 kidney allograft recipients and 75 non-transplanted individuals (control group). In contrast to herpesviruses, which was also investigated (CMV, HHV-6A, and B, HHV-7) MCPyV was detected predominantly in patients with oral lesions (gingivitis and/or periodontitis) of both transplanted and non-transplanted groups (P=0.

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Objective: Polyomavirus-associated nephropathy (PVAN) is a major cause of graft dysfunction after kidney transplantation. Therefore, routine screening for BK polyomavirus (BKV) infection with urine cytology or quantitative PCR-based assays has been recommended. Although less expensive than quantitative tests, qualitative PCR assays are not recommended for screening based on the assumption that their diagnostic accuracy is inferior to urine cytology.

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BK polyomavirus (BKV) is highly prevalent in the world population. Different reports indicate that BKV subtypes and subgroups present an uneven geographical distribution which might be correlated with human migration. However, there is a lack of data on the BKV subtype distribution in the South American population.

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Malaria is one of the most important tropical diseases and mainly affects populations living in developing countries. Reduced sensitivity of Plasmodium sp. to formerly recommended antimalarial drugs places an increasing burden on malaria control programs as well as on national health systems in endemic countries.

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We investigated the occurrence of HIV-1 antiretroviral resistance in individuals failing to respond to highly active antiretroviral therapy (HAART) attended by RENAGENO from 2001-2004. One hundred and seventeen patients were selected for this study; their plasma viral RNA was extracted and the PR and RT genes sequenced to examine subtype, genetic polymorphisms and mutations associated with resistance to antiretroviral drugs. HIV-1 sequence analysis showed that 86/100 (86%) were infected with subtype B, 7/100 (7%) with subtype F and 7/100 (7%) with RT/PR hybrid forms (2 D/B, 2 F/B, 2 B/F and 1 D/F).

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The presence of genetic mutations in HIV-1-positive untreated individuals and its contribution to treatment failure, either in an individual or on a population basis, remains an important concern. The goal was to analyze and compare HIV-1 reverse transcriptase (RT) and protease (PR) genes of untreated individuals with chronic and recent infections. Fifty-one chronic infected individuals for whom initiation of antiretroviral treatment had been recommended and 20 individuals with recent documented HIV-1 seroconversion had their plasma viral RNA extracted and the PR and RT genes sequenced in order to determine subtype, presence of genetic polymorphisms and mutations associated with resistance to antiretroviral drugs.

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The antibody response to Plasmodium falciparum parasites of naturally infected population is critical to elucidate the role of polymorphic alleles in malaria. Thus, we evaluated the impact of antigenic diversity of repetitive and family dimorphic domains of the merozoite surface protein 2 (MSP-2) on immune response of 96 individuals living in Peixoto de Azevedo (MT-Brazil), by ELISA using recombinant MSP-2 proteins. The majority of these individuals were carrying FC27-type infections.

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Here, we describe the standardization of a very sensitive and specific single Plasmodium vivax polymerase chain reaction (PCR) and its usefulness for diagnosis and screening procedures when a Plasmodium falciparum PCR was also utilized. The P. vivax PCR sensitivity threshold was 0.

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Article Synopsis
  • This study focused on the genetic variations in a specific part of the SERA gene from Plasmodium falciparum, a malaria-causing parasite, found in blood samples from infected individuals in the Brazilian Amazon.
  • Researchers used polymerase chain reaction to identify two DNA fragments related to the SERA protein, finding that a 199 bp fragment was more common in all regions studied, indicating a potential immune response influence.
  • The findings emphasize the importance of understanding genetic variability in P. falciparum as a crucial step towards developing a universal malaria vaccine.
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