Modelling ligand depletion for simultaneous affinity and binding site quantification on cells and tissue.

The quantification of the number of targets in biological systems is an important parameter to assess the suitability of surface markers as targets for drugs, drug delivery and medical imaging. Likewise, quantifying the interaction with the target in terms of affinity and binding kinetics is essential during drug development. Commonly used approaches to quantify membrane antigens on live cells are based on manual saturation techniques that are labour-intensive, require careful calibration of the generated signal and do not quantify the binding rates. Here, we present how measuring interactions in real-time on live cells and tissue under ligand depletion conditions can be used to simultaneously quantify the kinetic binding parameters as well as the number of available binding sites in a biological system. Suitable assay design was explored with simulated data and feasibility of the method verified with experimental data for exemplary low molecular weight peptide and antibody radiotracers as well as fluorescent antibodies. In addition to revealing the number of accessible target sites and improving the accuracy of binding kinetics and affinities, the presented method does not require knowledge about the absolute signal generated per ligand molecule. This enables a simplified workflow for use with both radioligands and fluorescent binders.

Análisis clínico y radiográfico del vástago de cadera no cementado "CEMENTFREE"® de fabricación nacional. Resultados a corto plazo / Clinical and radiographic analysis of the CemenTFRee® uncemented hip stem of national manufacture. Short-term results

Introducción: La estabilidad del componente femoral y su resistencia al hundimiento son factores críticos para lograr una correcta osteointegración y el éxito clínico de la artroplastia total de cadera no cementada. Hay pocos estudios que evalúen los resultados con vástagos de fabricación nacional, aun los de corto y mediano plazo. El objetivo de este estudio fue realizar un análisis clínico y radiográfico de pacientes sometidos a un reemplazo total de cadera con implante de un componente femoral de fabricación nacional (CEMENTFREE®). Materiales y métodos: Se llevó a cabo un estudio retrospectivo con pacientes sometidos a un reemplazo total de cadera con vástago CEMENTFREE®, entre enero de 2015 y agosto de 2020, a cargo del mismo cirujano y en la misma institución. Resultados: Se implantaron 46 vástagos sin cementación en 42 pacientes (rango etario: 60-81 años). El seguimiento promedio fue de 3 años (mín. 1 año, máx. 5 años). Aplicando el Harris Hip Score se observó una franca mejoría (promedio 47 en el preoperatorio y 93 después de la cirugía). La tasa de supervivencia fue del 100% a los 5 años. Conclusión: La artroplastia de cadera con el vástago CEMENTFREE® de fabricación nacional ha demostrado ser una opción comparable con otros vástagos importados, en cuanto a los resultados clínicos y radiográficos a corto plazo. Resta evaluar los resultados a mediano y largo plazo. Nivel de Evidencia: IV

Introduction: The stability of the femoral component and its resistance to subsidence are critical factors to achieve correct osseointegration and subsequent clinical success in cementless total hip arthroplasty. Few studies have evaluated the results of nationally manufactured stems, even in the short and medium term. Our objective is to clinically and radiologically analyze patients undergoing a total hip replacement with a nationally manufactured femoral component (Cementfree® stem).materials and methods: We carried out a retrospective study on patients who had undergone a total hip replacement with the Cementfree® stem between January 2015 and August 2020 by the same surgeon and at the same institution.Results: 46 uncemented stems were implanted in 42 patients with an age range between 60 and 81 years. The average follow-up was 3 years, with a minimum of 1 year and a maximum of 5 years. There was an evident improvement in the Harris Hip Score (an average of 47 preoperatively vs. 93 after surgery). The revision of the stem for aseptic loosening, in the Kaplan Meier analysis, demonstrated a 100% survival rate at 5 years. Conclusion: According to the results obtained in this research, hip arthroplasty with the nationally manufactured Cementfree® stem has proven to be an option comparable to other imported stems in terms of short-term clinical and radiographic outcomes. An evaluation of the outcomes in the medium and long term is pending. Level of Evidence: IV

Contribution of mesolimbic dopamine and kappa opioid systems to the transition from acute to chronic pain.

Decreased dopaminergic activity and increased kappa opioid activity in the mesolimbic system underlie the negative emotional states related to chronic pain. However, it is not known whether these changes are just consequence of chronic pain or contribute to the sensorial changes associated with chronic pain. In this study, we asked whether the mesolimbic dopamine and kappa opioid systems contribute to the development and maintenance of chronic hyperalgesia, one of the most common sensorial changes related to chronic pain. The lesion of the dopaminergic cells of the ventral tegmental area prevented the transition from acute to chronic hyperalgesia when performed in pain-free rats, but did not affect the maintenance of chronic hyperalgesia, when performed in chronic pain in rats. As hyperalgesia becomes chronic, the dopamine levels in the nucleus accumbens decrease. The blockade of the kappa opioid receptors in the nucleus accumbens both prevented and reversed the development of chronic hyperalgesia, but did not affect its maintenance. Complementarily, the pharmacological activation of the kappa opioid receptors in the nucleus accumbens facilitated the transition from acute to chronic hyperalgesia. None of these interventions affected acute hyperalgesia. These findings suggest that the mesolimbic dopamine and kappa opioid systems specifically drive the pain chronification process, without affecting acute pain or the maintenance of chronic pain.

Maternal and fetal outcome of pregnancy in Swiss mice infected with Plasmodium berghei ANKAGFP.

Malaria in pregnant women is associated with risk of maternal and perinatal morbidity and mortality, and there are few antimalarial drugs considered safe to treat them, so it is necessary to develop safer antimalarial medicines. The goal of this study was to develop an animal model for human malaria during pregnancy by characterizing the maternal and fetal outcomes in malaria infected Swiss mice. For that, in the present study, we evaluated the outcome of pregnancy in Swiss mice infected with Plasmodium berghei ANKAGFP. We observed a reduction of fetal body weight and signs of skeletal ossification retardation in the offspring of mice infected on GD 12. The group of mice infected with malaria presented premature deliveries and histopathology changes consistent with placental malaria. Our study suggests that Swiss Webster mice infected with P. berghei ANKAGFP on GD 12 might be a valuable model to investigate the safety and the efficacy of new antimalarial drugs indicated to pregnant women.

Chlorpyrifos induces anxiety-like behavior in offspring rats exposed during pregnancy.

Chlorpyrifos is a pesticide, member of the organophosphate class, widely used in several countries to manage insect pests on many agricultural crops. Currently, chlorpyrifos health risks are being reevaluated due to possible adverse effects, especially on the central nervous system. The aim of this study was to investigate the possible action of this pesticide on the behaviors related to anxiety and depression of offspring rats exposed during pregnancy. Wistar rats were treated orally with chlorpyrifos (0.01, 0.1, 1 and 10mg/kg/day) on gestational days 14-20. Male offspring behavior was evaluated on post-natal days 21 and 70 by the elevated plus-maze test, open field test and forced swimming test. The results demonstrated that exposure to 0.1, 1 or 10mg/kg/day of chlorpyrifos could induce anxiogenic-like, but not depressive-like behavior at post-natal day 21, without causing fetal toxicity. This effect was reversed on post-natal day 70.

Fluctuations in Trypanosoma cruzi discrete typing unit composition in two naturally infected triatomines: Mepraia gajardoi and M. spinolai after laboratory feeding.

Mepraia species are hematophagous insects and the most important wild vectors of Trypanosoma cruzi, the causative agent of Chagas disease in southeastern South America. Because the domestic Triatoma infestans is already controlled, the transmission of different T. cruzi discrete typing units (DTUs) by Mepraia species deserves attention. Our aim is to gather information on the diversity of T. cruzi DTUs circulating in natural insect populations. Two groups of naturally infected bugs 21 Mepraia gajardoi and 26 Mepraia spinolai were followed-up after two or more laboratory feedings by means of minicircle-PCR assays to evaluate the composition of four T. cruzi DTUs by hybridization tests. Fluctuations from positive T. cruzi detection to negative and the converse, as well as single to mixed infections with different T. cruzi DTUs and the opposite were frequent observations after laboratory feeding in both Mepraia species. Single and mixed infections with more than two T. cruzi DTUs were detected after the first feeding; however mainly mixed infections prevailed after the second feeding. Laboratory feeding on three or more occasions resulted in a decreasing trend of the parasite burden. In a comparison with 28 infected and fed M. gajardoi collected one year before from the same vector colony T. cruzi DTUs composition changed, indicating that temporal variations occur in T. cruzi. Natural populations of Mepraia species can transmit complex mixtures T. cruzi DTUs which fluctuate over time after feeding, with a tendency to eliminate the parasitism after prolonged feeding.

The Nav1.2 channel is regulated by GSK3.

BACKGROUND: Phosphorylation plays an essential role in regulating voltage-gated sodium (Na(v)) channels and excitability. Yet, a surprisingly limited number of kinases have been identified as regulators of Na(v) channels. We posited that glycogen synthase kinase 3 (GSK3), a critical kinase found associated with numerous brain disorders, might directly regulate neuronal Na(v) channels. METHODS: We used patch-clamp electrophysiology to record sodium currents from Na(v)1.2 channels stably expressed in HEK-293 cells. mRNA and protein levels were quantified with RT-PCR, Western blot, or confocal microscopy, and in vitro phosphorylation and mass spectrometry to identify phosphorylated residues. RESULTS: We found that exposure of cells to GSK3 inhibitor XIII significantly potentiates the peak current density of Na(v)1.2, a phenotype reproduced by silencing GSK3 with siRNA. Contrarily, overexpression of GSK3ß suppressed Na(v)1.2-encoded currents. Neither mRNA nor total protein expression was changed upon GSK3 inhibition. Cell surface labeling of CD4-chimeric constructs expressing intracellular domains of the Na(v)1.2 channel indicates that cell surface expression of CD4-Na(v)1.2 C-tail was up-regulated upon pharmacological inhibition of GSK3, resulting in an increase of surface puncta at the plasma membrane. Finally, using in vitro phosphorylation in combination with high resolution mass spectrometry, we further demonstrate that GSK3ß phosphorylates T(1966) at the C-terminal tail of Na(v)1.2. CONCLUSION: These findings provide evidence for a new mechanism by which GSK3 modulates Na(v) channel function via its C-terminal tail. GENERAL SIGNIFICANCE: These findings provide fundamental knowledge in understanding signaling dysfunction common in several neuropsychiatric disorders.

Trypanosoma cruzi infection in Mepraia gajardoi and Mepraia spinolai: the effect of feeding nymphs from the field.

We evaluated Trypanosoma cruzi infection rates by means of minicircle DNA-based polymerase chain reactions (PCRs) in 70 starved Mepraia gajardoi from northern Chile and 65 M. spinolai from central Chile after feeding. Immediately after collection in the field, 20% of M. gajardoi were found infected; after feeding, 67% of the uninfected were infected. One group of M. spinolai seemed to be completely uninfected, but after the first and second feedings, 62% and 59% were positive, respectively.

Trypanosoma cruzi genotypes in Mepraia gajardoi from wild ecotopes in northern Chile.

We evaluated Trypanosoma cruzi infection in 397 wild Mepraia gajardoi specimens from five coastal localities in northern Chile by detection of minicircle DNA by polymerase chain reaction. The wild capture sites were classified into two ecotopes: a fully wild ecotope (ecotope 1) and a wild ecotope near human dwellings (ecotope 2). Infection rates varied between 11% and 27%. Minicircle hybridization assays showed that T. cruzi lineages Tc II and Tc VI were commonly detected in ecotope 1 and ecotope 2, respectively. These results are discussed in the context of insect proximity to human dwellings, the alimentary profile of Mepraia sp., T. cruzi lineages detected in the past in the same disease-endemic area circulating in humans, and Triatoma infestans.