Kinetics, mechanism, and tautomerism in ametryn acid hydrolysis: From molecular structure to environmental impacts.

The excessive use of pesticides and the demand for environmentally friendly compounds have driven the focus to detailed studies of the environmental destination of these compounds. Degradation by hydrolysis of pesticides, when released into the soil, can result in the formation of metabolites with potentially adverse effects on the environment. Moving in this direction, we investigated the mechanism of acid hydrolysis of the herbicide ametryn (AMT) and predicted the toxicities of metabolites through experimental and theoretical approaches. The formation of ionized hydroxyatrazine (HA) occurs with the release of the SCH3- group and the addition of H3O+ to the triazine ring. The tautomerization reactions privileged the conversion of AMT into HA. Furthermore, the ionized HA is stabilized by an intramolecular reaction that provides the molecule in two tautomeric states. Experimentally, the hydrolysis of AMT was obtained under acidic conditions and at room temperature with HA as the main product. HA was isolated in a solid state through its crystallization as organic counterions. The mechanism of conversion of AMT to HA and the experimental investigation of the reaction kinetics allowed us to determine the dissociation of CH3SH as the rate-controlling step in the degradation process that culminates in a half-life between 7 and 24 months under typical acid soil conditions of the Brazilian Midwest - region with strong agricultural and livestock vocation. The keto and hydroxy metabolites showed substantial thermodynamic stability and a decrease in toxicity compared to AMT. We hope that this comprehensive study will support the understanding of the degradation of s-triazine-based pesticides.

A high-throughput 3D bioprinted cancer cell migration and invasion model with versatile and broad biological applicability.

Understanding the underlying mechanisms of migration and metastasis is a key focus of cancer research. There is an urgent need to develop in vitro 3D tumor models that can mimic physiological cell-cell and cell-extracellular matrix interactions, with high reproducibility and that are suitable for high throughput (HTP) drug screening. Here, we developed a HTP 3D bioprinted migration model using a bespoke drop-on-demand bioprinting platform. This HTP platform coupled with tunable hydrogel systems enables (i) the rapid encapsulation of cancer cells within in vivo tumor mimicking matrices, (ii) in situ and real-time measurement of cell movement, (iii) detailed molecular analysis for the study of mechanisms underlying cell migration and invasion, and (iv) the identification of novel therapeutic options. This work demonstrates that this HTP 3D bioprinted cell migration platform has broad applications across quantitative cell and cancer biology as well as drug screening.

A Covalently Crosslinked Ink for Multimaterials Drop-on-Demand 3D Bioprinting of 3D Cell Cultures.

In vitro 3D cell models have been accepted to better recapitulate aspects of in vivo organ environment than 2D cell culture. Currently, the production of these complex in vitro 3D cell models with multiple cell types and microenvironments remains challenging and prone to human error. Here, a versatile ink comprising a 4-arm poly(ethylene glycol) (PEG)-based polymer with distal maleimide derivatives as the main ink component and a bis-thiol species as the activator that crosslinks the polymer to form the hydrogel in less than a second is reported. The rapid gelation makes the polymer system compatible with 3D bioprinting. The ink is combined with a novel drop-on-demand 3D bioprinting platform, designed specifically for producing 3D cell cultures, consisting of eight independently addressable nozzles and high-throughput printing logic for creating complex 3D cell culture models. The combination of multiple nozzles and fast printing logic enables the rapid preparation of many complex 3D cell cultures comprising multiple hydrogel environments in one structure in a standard 96-well plate format. The platform's compatibility for biological applications is validated using pancreatic ductal adenocarcinoma cancer (PDAC) and human dermal fibroblast cells with their phenotypic responses controlled by tuning the hydrogel microenvironment.

Associations between inflammatory markers and muscle strength in older adults according to the presence or absence of obesity.

BACKGROUND: We investigated the association between inflammatory markers and muscle strength in older adults according to the presence or absence of obesity. Dynapenia is the age-related decline in muscle strength and results in negative outcomes to older adults. Accordingly, obesity is more prevalent throughout aging and is associated with comorbidities, such as type 2 diabetes, dyslipidemia and cardiovascular diseases. Both dynapenia and obesity are strongly linked to chronic inflammation, sharing common signaling pathways. METHODS: We recruited 247 older adults aged 60 or older and collected sociodemographic, anthropometric and metabolic data. Dynapenia was diagnosed according to the European Working Group on Sarcopenia in Older People 2 (EWGSOP2) criteria. Circulating inflammatory cytokines were measured in plasma using a multiplex panel kit. Anthropometric, sociodemographic, lipid profile, and fasting blood glucose were also assessed. RESULTS: Dynapenic participants were predominantly males (74.4%), had insufficiently active lifestyle and higher IL-10 plasma levels (0.95 pg/mL; 0.40-2.12). The prevalence of obesity was higher among non-dynapenic participants (45.3%; 95% CI, 37.7-53). In dynapenic older adults, obesity was predominant in males (53.6%) and subjects with normal muscle strength had higher serum levels of TNF-ß (0.63 pg/mL; 0.30-1.30) and lower hand-grip strength (24 kg; 20.00-28.00). Using a multivariate quantile regression analysis, we found a strong and negative association between IL-10 and muscle strength. CONCLUSIONS: This study can help to understand the association of inflammation, obesity and muscle strength to promote interventions in order to avoid or delay the negative outcomes associated with dynapenia and sarcopenia in older adults.

A 3D Bioprinter Specifically Designed for the High-Throughput Production of Matrix-Embedded Multicellular Spheroids.

3D in vitro cancer models are important therapeutic and biological discovery tools, yet formation of matrix-embedded multicellular spheroids prepared in high-throughput (HTP), and in a highly controlled manner, remains challenging. This is important to achieve robust and statistically relevant data. Here, we developed an enabling technology consisting of a bespoke drop-on-demand 3D bioprinter capable of HTP printing of 96-well plates of spheroids. 3D multicellular spheroids are embedded inside a hydrogel matrix with precise control over size and cell number, with the intra-experiment variability of embedded spheroid diameter coefficient of variation being between 4.2% and 8.7%. Application of 3D bioprinting HTP drug screening was demonstrated with doxorubicin. Measurements of IC50 values showed sensitivity to spheroid size, embedding, and how spheroids conform to the embedding, revealing parameters shaping biological responses in these models. Our study demonstrates the potential of 3D bioprinting as a robust HTP platform to screen biological and therapeutic parameters.