Maximiliano Giraud-Billoud

Wastewater-Based Epidemiology (WBE) has emerged as a critical tool for monitoring SARS-CoV-2 circulation at the community level. This study assessed spatiotemporal viral dynamics in Las Heras, Mendoza, Argentina, by comparing wastewater samples from six sewer maintenance holes and three wastewater treatment plants (WWTPs) between January and June 2021, and by conducting long-term surveillance at Campo Espejo WWTP during epidemic (2020–2021) and endemic (2024–2025) phases of COVID-19. Viral particles from sewer manholes and WWTPs samples were concentrated by polyethylene glycol precipitation or aluminum polychloride adsorption–precipitation methods, and then SARS-CoV-2 RNA was quantified by reverse transcription quantitative polymerase chain reaction targeting N1 and N2 nucleocapsid viral markers. Results showed consistent detection of viral RNA across all sites, with peaks in wastewater preceding diagnosed COVID-19 cases increases, confirming WBE as an early-warning system. Localized sewer sampling identified urban hotspots, while WWTPs monitoring captured broader epidemiological trends. Recently, COVID-19 surveillance showed lower and intermittent viral loads, decoupled from diagnosed cases, compared to epidemic phase, indicating a transition to endemic circulation. Overall, combining upstream and downstream WBE enhanced spatial and temporal resolution, demonstrating its utility for public health monitoring during both epidemic and endemic phases.

Argentina is among the top consumers of herbicides, yet studies on their environmental and health impact remain scarce. This work aimed to evaluate the effects of herbicide exposure on Pomacea canaliculata as potential biomarkers of contamination. Specifically, we investigated whether paraquat (Pq) and fluroxypyr (Fx) alter enzymatic antioxidant defenses in tissues following acute exposure and induce histological modifications in the digestive gland (DG), particularly in symbiotic corpuscles, after chronic exposure. The nominal no-observed-effect concentration on lethality (NOEC_L) values were 3.62 µg/g dry mass (DM) for Pq and 10.42 µg/g DM for Fx. After acute exposure, superoxide dismutase activity decreased in the DG but increased in the kidney for both herbicides. Catalase activity decreased in the gills but increased in the kidneys of exposed snails, while glutathione-S-transferase activity increased in the DG and kidney after Pq exposure. Following chronic exposure (Pq: 1.45 µg/g DM; Fx: 6.94 µg/g DM), epithelial thickening and vacuolization were observed in Fx-exposed snails. Morphometric analysis of the DG showed that Pq reduced the epithelial occupancy of the symbiont’s vegetative form while increasing its cystic form. These findings indicate that both herbicides impact antioxidant defenses, DG function and host–symbiont interactions, reinforcing the suitability of P. canaliculata as bioindicator organisms.

The freshwater gastropod Pomacea canaliculata fulfills the ideal conditions of a bioindicator species since its digestive gland bioconcentrates elements toxic for human and ecosystems health. The aim of this work was to study the balance between production of free radicals and antioxidant defenses, and the generation of oxidative damage in the digestive gland of this mollusk after exposure (96 h) to three elements with differential affinities for functional biological groups: mercury (5.5 μg/L of Hg⁺² as HgCl₂), arsenic [500 μg/L of (AsO₄)⁻³ as Na₃AsO₄7H₂O], or uranium [700 μg/L of (UO₂)⁺² as UO₂(CH₂COOH)₂]. Bioconcentration factors of Hg, As, and U were 25, 23, and 53, respectively. Snails exhibited a sustained increase of reactive species (RS), and protein and lipid damage. Lipid radicals increased between 72 and 96 h, respectively, in snails exposed to U and Hg while this parameter changed early (24 h) in As- exposed snails. Snails showed protein damage, reaching maximum values at different endpoints. This redox disbalance was partially compensated by non-enzymatic antioxidant defenses α-tocopherol (α-T), β-carotene (β-C), uric acid, metallothionein (MTs). Snails consumed α-T and β-C in an element-dependent manner. The digestive gland consumed rapidly uric acid and this molecule was not recovered at 96 h. Digestive gland showed a significant increase in MTs after elemental exposure at different endpoints. The enzymatic antioxidant defenses, represented by the catalase and glutathione-S-transferase activities, seems to be not necessary for the early stages of the oxidative process by metals. This work is the first attempt to elucidate cellular mechanisms involved in the tolerance of this gastropod to non-essential elements. The bioconcentration factors and changes in the oxidative status and damage confirm that this species can be used as a bioindicator species of metal pollution in freshwater bodies.

States of natural dormancy include estivation and hibernation. Ampullariids are exemplary because they undergo estivation when deprived of water or hibernation when exposed to very low temperatures. Regardless of the condition, ampullariids show increased endogenous antioxidant defenses, anticipating the expected respiratory burst during reoxygenation after reactivation, known as “Preparation for Oxidative Stress (POS)”. In this work, we tested the POS hypothesis for changes in the blood and hemocytes of the bimodal breather Pomacea canaliculata (Ampullariidae) induced at experimental estivation and hibernation. We described respiratory (hemocyanin, proteins, lactate), antioxidant (GSH, uric acid, SOD, CAT, GST), and immunological (hemocyte levels, ROS production) parameters. We showed that, although the protein level remains unchanged in all experimental groups, hemocyanin increases in response to estivation. Furthermore, lactate remains unchanged in challenged snails, suggesting an aerobic metabolism during short-term challenges. Blood uric acid increases during estivation and arousal from estivation or hibernation, supporting the previously proposed antioxidant role. Regarding hemocytes, we showed that the total population increases with all challenges, and granulocytes increase during hibernation. We further showed that hibernation affects ROS production by hemocytes, possibly through mitochondrial inhibition. This study contributed to the knowledge of the adaptive strategies of ampullariids to tolerate adverse environmental conditions.

Background: Temporomandibular dysfunction (TMD) is a pathological entity related to functional problems of the joint and/or masticatory muscles. This entity is a public health problem studied for a long time, seeking to identify, among other characteristics, early identification strategies in order to reduce its chronic consequences. Aim: The aim of this study was to describe the results obtained in clinical dental and morphometric evaluations that can be routinely performed in a dental office, in order to verify if these allow an early diagnosis in children and adolescents with probable TMD. Methods: An observational, longitudinal and prospective study was carried out evaluating 36 mouth breathing patients aged 7-14 years, divided into two equal groups according to whether or not they had allergic rhinitis. DTM was studied by means of validated questionnaires and clinical tests, together with morphometric parameters calculated on radiographic images. Results: Tests and mouth breathing questionnaire showed significant differences between both groups. All the children in the control group had a mild disorder, while in the case group the totality was distributed between moderate (89%) and severe (11%) disorders. The movement indicator (Manglione index) showed that 83% of the patients in the control group were moderately impaired and 17% were severely impaired, while 100% of the patients in the case group were severely impaired at the time of consultation. The results of the morphometric analysis of the panoramic radiographs indicated that all patients with mouth breathing, whether due to allergic rhinitis or another cause, present differences in reference to condyle, ramus, body and ramus width symmetry between left and right side of the face in linear and angular measurements, with only the Condilion to Gnation distance being significantly lower in the cases. Conclusions: The diagnosis of DTM requires an oriented clinical examination to assess functional limitation. In addition, a complementary imaging study of low complexity such as panoramic radiography can allow visualization of changes such as the presence of osteophytes, which provide clarity to the diagnosis, given that pediatric patients do not always present the signs and symptoms classically described for adult patients.

Scientific evidence demonstrates, year after year, the importance of consolidating knowledge through meaningful educational experiences for students. This pedagogical approach focused on learning as the construction of meaning represents a much more profitable experience in the learning process, since it implies an active role of the student, leaving the comfort zone of being a mere receiver of knowledge. In this sense, medical education is increasingly adopting this thinking and is modifying curricular plans and ways of working with students in the search for transforming traditionalist approaches to education into educational forms that accompany the current era of knowledge, crossed by technologies and ubiquitous and autonomous learning

All female Pomacea canaliculata develop a small, male-like copulatory apparatus a few days after birth, which growths slowly until sexual maturity, and even further in older age. Previous studies have found trace elements like mercury (Hg), arsenic (As) and uranium (U) in tap water used for snail culture, and that these elements were accumulated in snail tissues. Here, we test whether the presence of these metals at maximum allowed concentrations (Environmental Protection Agency - EPA) in aquarium water could affect the development of the copulatory apparatus in mature females. Females of different ages were used as controls, grown in reconstituted metal-free water with or without the addition of Hg, As and U, as well as tributyltin (TBT), a compound used as masculinizing agent. Six and seven months old females cultured in tap water showed a longer penis and penile sheath, and a greater overall development of the copulatory apparatus, measured by an index (DI), as compared with same-age females cultured in reconstituted water. Moreover, when females were exposed to Hg, As or U at the maximum contaminant levels for human consumption allowed by EPA regulations, there was no further development of the copulatory apparatus, while there was a clearly positive effect in TBT-exposed females. This study confirms the masculinizing effect of organotin compounds on female copulatory apparatus and discusses the usefulness of the development of these organs as a bioindicator of environmental pollution.