Renato Martins da Silva

A bstract: Phenotypic, genetic and metabolic tumour heterogeneity is a major factor contributing to cancer progression, metastasis, and resistance to therapy. Distinctive thermal and proton flux patterns can occur in cancer cells as a function of variations in the metabolic rate of the tumour mass, tumour margins, and normal tissues, which can be detected by video thermometry (VTM) as well as by Scanning Ion-selective Electrode Techniques (SIET). This study presents distinct thermal patterns associated with tumour heterogeneity observed in canine mammary cancer using VTM and investigate the correlation between these thermometric signatures with metabolic changes related to V-ATPase activity by comparing real-time VTM data with that from concanamycin-sensitive ATP hydrolysis and cell proton flux measurements. The results demonstrate that integrating SIET and VTM data sets can reveal metabolic signatures to assist the diagnosis, surgery and therapeutic monitoring. Considering the breast cancer hallmarks conservation in human, canines and other mammals, this study provides a first bioenergetic proof-of-concept for the potential of the integration of the VTM technology with enzymatic and electrophysiological analyses sensitive to concanamycin for the development of more effective diagnostic, prognostic and therapeutic approaches in veterinary as well as in preclinical medical studies.

In the year 2019, a highly virulent coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged, precipitating the outbreak of the illness known as coronavirus disease 2019 (COVID-19). The commonly employed reverse transcription polymerase chain reaction (RT-qPCR) methodology serves to estimate the viral load in each patient’s sample by employing a standard curve. However, it is imperative to recognize that this technique exhibits limitations with respect to clinical diagnosis and therapeutic applications, since an advancement of the conventional polymerase chain reaction methods, digital polymerase chain reaction (digital PCR or DDPCR), enables the direct quantification and clonal amplification of nucleic acid strands. The primary divergence between dPCR and traditional PCR resides in their approaches to measuring nucleic acid quantities. In this study, we investigated the viral loads of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) within 461 participants. By employing both RT-qPCR and DDPCR techniques, we established a comparison between the quantification methodologies of the two approaches. Our findings illustrate that the quantification through DDPCR affords a superior means of monitoring viral load within lower respiratory tract samples, thus enhancing the assessment of disease progression, particularly in scenarios characterized by low viral loads.

Ticks are hematophagous ectoparasites that transmit pathogens and inflict significant economic losses on the cattle industry. Remarkably, they can survive extended periods of starvation in the absence of a host. The primary objective of this study was to investigate the metabolic adaptations that enable the tick Rhipicephalus microplus to endure starvation using the BME26 cell line as a model system. To simulate nutrient deprivation, cells were subjected to starvation conditions by replacing the L-15 culture medium with phosphate-buffered saline (PBS). Our findings show that these tick cells can endure experimental starvation for up to 48 h. The assessment of glycogen levels in starved cells shows a significant decrease, at both the 24 h and 48 h marks. Additionally, upregulation of phosphoenolpyruvate carboxykinase (PEPCK) gene expression, along with downregulation of hexokinase (HK) and pyruvate kinase (PK) gene expression, indicated that BME26 cells would prioritize the gluconeogenic pathway over the glycolytic pathway under starvation conditions. Moreover, the transcriptional levels of autophagy-related genes (ATG) were upregulated in response to starvation. Taken together, our findings suggest a potential role for autophagy in supplying substrates for the gluconeogenic pathway in nutrient-deprived tick cells. This work contributes to the understanding of metabolic regulation in R. microplus ticks and offers valuable insights for tick control strategies.

The enzyme glucose-6-phosphate dehydrogenase (G6PDH) plays crucial roles in glucose homeostasis and the pentose phosphate pathway (PPP), being also involved in redox metabolism. The PPP is an important metabolic pathway that produces ribose and nicotinamide adenine dinucleotide phosphate (NADPH), which are essential for several physiologic and biochemical processes, such as the synthesis of fatty acids and nucleic acids. As a rate-limiting step in PPP, G6PDH is a highly conserved enzyme and its deficiency can lead to severe consequences for the organism, in particular for cell growth. Insufficient G6PDH activity can lead to cell growth arrest, impaired embryonic development, as well as a reduction in insulin sensitivity, inflammation, diabetes, and hypertension. While research on G6PDH and PPP has historically focused on mammalian models, particularly human disorders, recent studies have shed light on the regulation of this enzyme in arthropods, where new functions were discovered. This review will discuss the role of arthropod G6PDH in regulating redox homeostasis and immunometabolism and explore potential avenues for further research on this enzyme in various metabolic adaptations.

In the year 2019, a highly virulent coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged, precipitating the outbreak of the illness known as coronavirus disease 2019 (COVID-19). The commonly employed reverse transcription–polymerase chain reaction (RT-PCR) methodology serves to estimate the viral load in each patient's sample by employing a standard curve. However, it is imperative to recognize that this technique exhibits limitations with respect to clinical diagnosis and therapeutic applications, since an advancement of the conventional polymerase chain reaction methods, digital polymerase chain reaction (digital PCR or ddPCR), enables the direct quantification and clonal amplification of nucleic acid strands. The primary divergence between dPCR and traditional PCR resides in their approaches to measuring nucleic acid quantities. In this study, we investigated the viral loads of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) within 461 participants. By employing both RT-qPCR and ddPCR techniques, we established a comparison between the quantification methodologies of the two approaches. Our findings illustrate that the quantification through ddPCR affords a superior means of monitoring viral load within lower respiratory tract samples, thus enhancing the assessment of disease progression, particularly in scenarios characterized by low viral loads.

The indiscriminate use of acaricides is a problem worldwide and has increased the selection of acaricide-resistant tick populations. The goal of this study was to evaluate the acaricide effects of two essential oils (from Schinus molle and Bulnesia sarmientoi) using the larval immersion test on three Rhipicephalus tick species. Rhipicephalus evertsi, Rhipicephalus appendiculatus and Rhipicephalus pulchelus ticks collected in Kenya, without history of acaricide exposure, were tested, as well as individuals from two populations of Rhipicephalus microplus (with or without history of acaricide exposure), for comparison. The sample most resistant to the treatments was a population of R. microplus with previous acaricide exposure, whereas the least tolerant sample was a strain of the same species that never had contact with acaricides (Porto Alegre strain). Interestingly, the field tick samples without previous acaricide exposure responded to essential oils with a mortality profile resembling that observed in the acaricide-resistant R. microplus field population, and not the susceptible Porto Alegre strain. The essential oil of B. sarmientoi and its two components tested (guaiol and bulnesol) caused the highest mortality rates in the tested species and are potential molecules for future studies on control methods against these species.