The indole motif is essential for the antitrypanosomal activity of N5-substituted paullones.

Severe infections with potentially fatal outcomes are caused by parasites from the genera Trypanosoma and Leishmania (class Kinetoplastea). The diseases affect people of remote areas in the tropics and subtropics with limited access to adequate health care. Besides insufficient diagnostics, treatment options are limited, with tenuous developments in recent years. Therefore, new antitrypanosomal antiinfectives are required to fight these maladies. In the presented approach, new compounds were developed and tested on the target trypanothione synthetase (TryS). This enzyme is crucial to the kinetoplastids' unique trypanothione-based thiol redox metabolism and thus for pathogen survival. Preceding studies have shown that N5-substituted paullones display antitrypanosomal activity as well as TryS inhibition. Herein, this compound class was further examined regarding the structure-activity relationships (SAR). Diverse benzazepinone derivatives were designed and tested in cell-based assays on bloodstream Trypanosoma brucei brucei (T. b. brucei) and intracellular amastigotes of Leishmania infantum (L. infantum) as well as in enzyme-based assays on L. infantum TryS (LiTryS) and T. b. brucei TryS (TbTryS). While an exchange of just the substituent in the 9-position of paullones led to potent inhibitors on LiTryS and T. b. brucei parasites, new compounds lacking the indole moiety showed a total loss of activity in both assays. Conclusively, the indole as part of the paullone structure is pivotal for keeping the TryS inhibitory and antitrypanosomal activity of this substance class.

Hybrid Controller Based on Numerical Methods for Chemical Processes with a Long Time Delay.

A hybrid control framework is proposed as an alternative for long time delays in chemical processes. The hybrid approach mixes the numerical methods in an internal mode control (IMC) structure, which uses the particle swarm optimization (PSO) algorithm to improve the adjustment of the controller parameters. Simulation tests are carried out on linear systems of high order and inverse response, both with dominant delay, and tests on a nonlinear process (chemical reactor). The performance of the proposed controller is stable and satisfactory despite nonlinearities in various operating conditions, set-point changes, process disturbances, and modeling errors. In addition, experimental tests were performed on a setup composed of two heaters and two temperature sensors mounted on an Arduino microcontroller-based board called the Temperature Control Laboratory (TCLab), with an additional software delay introduced. The merits and drawbacks of each scheme are analyzed using radar charts, comparing the control methods with different performance measures for set-point and disturbance changes. Furthermore, the new controller uses PSO to improve the tuning parameters.

Discovery of Antitrypanosomal Indolylacetamides by a Deconstruction-Optimization Strategy Applied to Paullones.

The parasitic kinetoplastid diseases Leishmaniasis, Chagas disease and Human African Trypanosomiasis constitute serious threats for populations throughout the (sub-)tropics. Most available drugs to treat these diseases possess inadequate properties and candidates to fill the drug pipeline are urgently needed. Paullone-N5 -acetamides inhibit trypanothione synthetase (TryS), an essential kinetoplastid enzyme, and exhibit antiparasitic activity in the low micromolar range, but lack the desired selectivity against mammalian cells (selectivity index (SI):<10). With the aim to identify the paullones' moieties responsible for TryS inhibition and bioactivity, we applied molecular simplification and ring disconnection approaches. The new indolylacetamides lost activity against the expected molecular target (TryS) compared to the reference paullone MOL2008 (Leishmania infantum TryS IC50 : 150 nM; Trypanosoma brucei bloodstream form EC50 : 4.3 µM and SI: 2.4). However, several of them retained potency (T. b. brucei EC50 : 2.4-12.0 µM) and improved selectivity (SI: 5 to >25).

Mode of action of p-quinone derivatives with trypanocidal activity studied by experimental and in silico models.

Quinones are attractive pharmacological scaffolds for developing new agents for the treatment of different transmissible and non-transmissible human diseases due to their capacity to alter the cell redox homeostasis. The bioactivity and potential mode of action of 19 p-quinone derivatives fused to different aromatic rings (carbo or heterocycles) and harboring distinct substituents were investigated in infective Trypanosoma brucei brucei. All the compounds, except for a furanequinone (EC50=38 µM), proved to be similarly or even more potent (EC50 = 0.5-5.5 µM) than the clinical drug nifurtimox (EC50 = 5.3 µM). Three furanequinones and one thiazolequinone displayed a higher selectivity than nifurtimox. Two of these selective hits resulted potent inhibitors of T. cruzi proliferation (EC50=0.8-1.1 µM) but proved inactive against Leishmania infantum amastigotes. Most of the p-quinones induced a rapid and marked intracellular oxidation in T. b. brucei. DFT calculations on the oxidized quinone (Q), semiquinone (Q•-) and hydroquinone (QH2) suggest that all quinones have negative ΔG for the formation of Q•-. Qualitative and quantitative structure-activity relationship analyses in two or three dimensions of different electronic and biophysical descriptors of quinones and their corresponding bioactivities (killing potency and oxidative capacity) were performed. Charge distribution over the quinone ring carbons of Q and Q.- and the frontier orbitals energies of SUMO (Q.-) and LUMO (Q) correlate with their oxidative and trypanocidal activity. QSAR analysis also highlighted that both bromine substitution in the p-quinone ring and a bulky phenyl group attached to the furane and thiazole rings (which generates a negative charge due to the π electron system polarized by the nearby heteroatoms) are favorable for activity. By combining experimental and in silico procedures, this study disclosed important information about p-quinones that may help to rationally tune their electronic properties and biological activities.

Correction to: Populus alba cationic cell-wall-bound peroxidase (CWPO-C) regulates the plant growth and affects auxin concentration in Arabidopsis thaliana.

[This corrects the article DOI: 10.1007/s12298-022-01241-0.].

Discovery of novel Leishmania major trypanothione synthetase inhibitors by high-throughput screening.

Leishmaniasis is an infectious disease caused by obligate intracellular protozoa of the genus Leishmania with high infection and death rates in developing countries. New drugs with better pharmacological performance with regards to safety, efficacy, toxicity, and drug resistance than those/the ones currently used are urgently needed. Trypanothione synthetase (TryS) is an attractive target for the development of drugs against leishmaniasis because it is specific and essential to kinetoplastid parasites. In this study, Leishmaniamajor TryS was expressed and purified, and the kinetic parameters of purified TryS were determined. To identify novel inhibitors of LmTryS, a high-throughput screening (HTS) assay was developed and used to screen a library of 35,040 compounds. In the confirmatory assay, 42 compounds displayed half maximal inhibitory concentration (IC50) values < 50 µM and six of them corresponded to novel structures with IC50 ranging from 9 to 19 µM against LmTryS enzyme activity. Of the six inhibitors, TS001 showed the highest activity against growth of L. major promastigotes, L. donovani promastigotes, and Trypanosoma brucei brucei Lister 427 with IC50 values of 17, 26, and 31 µM, respectively. An in silico docking study using a homology model of LmTryS predicted the molecular interactions between LmTryS and the inhibitors.

Populus alba cationic cell-wall-bound peroxidase (CWPO-C) regulates the plant growth and affects auxin concentration in Arabidopsis thaliana.

The poplar cationic cell-wall-bound peroxidase (CWPO-C) mediates the oxidative polymerization of lignin precursors, especially sinapyl alcohols, and high molecular weight compounds that cannot be oxidized by other plant peroxidases, including horseradish peroxidase C. Therefore, CWPO-C is believed to be a lignification-specific peroxidase, but direct evidence of its function is lacking. Thus, the CWPO-C expression pattern in Arabidopsis thaliana (Arabidopsis) was determined using the ß-glucuronidase gene as a reporter. Our data indicated that CWPO-C  was expressed in young organs, including the meristem, leaf, root, flower, and young xylem in the upper part of the stem. Compared with the wild-type control, transgenic Arabidopsis plants overexpressing CWPO-C had shorter stems. Approximately 60% of the plants in the transgenic line with the highest CWPO-C content had curled stems. These results indicate that CWPO-C plays a role in cell elongation. When plants were placed horizontally, induced CWPO-C expression was detected in the curved part of the stem during the gravitropic response. The stem curvature associated with gravitropism is controlled by auxin localization. The time needed for Arabidopsis plants overexpressing CWPO-C placed horizontally to bend by 90° was almost double the time required for the similarly treated wild-type controls. Moreover, the auxin content was significantly lower in the CWPO-C-overexpressing plants than in the wild-type plants. These results strongly suggest that CWPO-C has pleiotropic effects on plant growth and indole-3-acetic acid (IAA) accumulation. These effects may be mediated by altered IAA concentration due to oxidation. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01241-0.

Automatic identification of intestinal parasites in reptiles using microscopic stool images and convolutional neural networks.

Captive environments trigger the propagation and multiplication of parasites among different reptile species, thus weakening their immune response and causing infections and diseases. Technological advances of convolutional neural networks have opened a new field for detecting and classifying diseases which have shown great potential to overcome the shortcomings of manual detection performed by experts. Therefore, we propose an approach to identify six captive reptiles parasitic agents (Ophionyssus natricis, Blastocystis sp, Oxiurdo egg, Rhytidoides similis, Strongyloides, Taenia) or the absence of such parasites from a microscope stool images dataset. Towards this end, we first use an image segmentation stage to detect the parasite within the image, which combines the Contrast Limited Adaptive Histogram Equalization (CLAHE) technique, the OTSU binarization method, and morphological operations. Then, we carry out a classification stage through MobileNet CNN under a transfer learning scheme. This method was validated on a stool image dataset containing 3616 images data samples and 26 videos from the six parasites mentioned above. The results obtained indicate that our transfer learning-based approach can learn a helpful representation from the dataset. We obtained an average accuracy of 94.26% across the seven classes (i.e., six parasitic agents and the absence of parasites), which statistically outperformed, at a 95% confidence level, a custom CNN trained from scratch.

Gonococci resistant to current antimicrobial management standards: a new threat to global public health.

Gonorrhea is the second most common sexually transmitted bacterial infection on the planet and is caused by a Gram-negative cocco, Neisseria gonorrhoeae. Currently, the preferred regimen for the management of this disease in Brazil is a combination of antimicrobials, in this case, ceftriaxone and azithromycin. However, over time, the gonococcus developed a decrease in susceptibility to the regimen used, which resulted in frank resistance to antimicrobials, progressively reducing the therapeutic options available. Thus, the study presented here aims to analyze and discuss the current scenario of resistance of N. gonorrhoeae to the antimicrobials used to date, to encourage discussion on the subject in the academic environment. For this purpose, 47 articles indexed in the Bireme, PubMed, Scielo and UpToDate platforms were selected.

A Simple Bioluminescent Assay for the Screening of Cytotoxic Molecules Against the Intracellular Form of Leishmania infantum.

This chapter describes a viability assay for the intracellular (amastigote) and clinically relevant form of Leishmania infantum that is based on the detection of bioluminescence (BL) signal. The assay uses a reporter cell line of L. infantum that expresses constitutively a redshifted luciferase from Photinus pyralis and murine macrophages (cell line J774.A1) as host cells for infection. The host cell line was selected because it is a differentiated cell line, easy to manipulate in vitro, and advantageous for ethical reasons. This chapter introduces an assay designed for the screening of bioactive compounds/molecules employing a 96-well microplate and a 24 h treatment. The assay setup shows excellent balance between simplicity (cell culture manipulation/infection and timing) and quality parameters, as well as potential to detect drug-like molecules acting in a fast and cytotoxic manner.

A Simple, Robust, and Affordable Bioluminescent Assay for Drug Screening Against Infective African Trypanosomes.

This chapter introduces a simple and robust in vitro viability assay to screen bioactive small molecules (e.g., natural, synthetic) against the monomorphic and infective (bloodstream) form of Trypanosoma brucei brucei. The assay relies on a bioluminescent transgenic parasite harboring a genetically encoded copy of a thermostable redshifted firefly luciferase from Photinus pyralis.The major advantages of the assay are simplicity and cost efficiency, along with excellent quality parameters. The bioassay allows estimating parasite numbers and viability (and metabolic state) as a function of bioluminescence (BL) signal. Parasites are grown in the presence of the molecules of interest in a 96-well microplate, and 24 h later, BL is determined with a simple protocol lacking washing steps, using cost-efficient reagents with a reasonable readout time for high-throughput applications.

Caracterización clínica de la peritonitis secundaria en una institución de tercer nivel y factores relacionados con mortalidad / Clinical characterization of secondary peritonitis in a tertiary level of care institution and factors related to mortality

Introducción. La peritonitis secundaria es una enfermedad con altos índices de mortalidad, por lo que se considera de gran importancia identificar los factores que inciden en ella. Método. Se realizó un estudio analítico entre 2019 y 2020 en el que se incluyeron pacientes con peritonitis secundaria, se caracterizaron las variables más relacionadas con el pronóstico, como aspectos demográficos y clínicos, y se analizó la asociación entre la mortalidad y estas variables. Resultados. La mortalidad hospitalaria fue del 30,7 %, encontrando como condiciones relacionadas con la mortalidad la ubicación de la fuente séptica en abdomen superior, la presencia de dolor en abdomen superior, atención en UCI, control del foco en la primera intervención, pacientes que cursaron con falla renal, edad del paciente y valores de hemoglobina. Conclusiones. En la cohorte estudiada se encontraron índices de mortalidad dos veces superiores a los reportados en Suramérica y 1,5 veces a los del resto del país. El mayor poder predictivo de mortalidad en el análisis bivariado fue dado por la presencia de falla renal y el valor de la hemoglobina.

Introduction. Secondary peritonitis is a disease with high mortality rates, so it is considered of great importance to identify the factors that affect it. Methods. An analytical study was carried out between 2019 and 2020 in which patients with secondary peritonitis were included, the variables most related to prognosis were characterized, such as demographic and clinical aspects, and the association between mortality and these variables was analyzed. Results. Hospital mortality was 30.7%, finding conditions related to mortality to be the location of the septic source in the upper abdomen, the presence of pain in the upper abdomen, care in the ICU, control of the focus in the first intervention, patients who underwent kidney failure, patient age, and hemoglobin values. Conclusion. Mortality rates were found in the studied cohort twice higher than those reported in South America and 1.5 times higher than those of the rest of the country. The greatest predictive power of mortality in the bivariate analysis was given by the presence of kidney failure and hemoglobin.

Guillain-Barré syndrome in a COVID-19 patient / Síndrome de Guillain-Barré en paciente con COVID-19

Abstract Coronavirus type 2 is a P-coronavirus whose infection is characterized by a predominantly respiratory clinical picture. However, neurological symptoms are garnering great interest related to pulmonary infection and direct viral invasion of the central nervous system, with a possible association between Guillain-Barré syndrome and SARS-CoV-2 infection. This report describes this relationship in a 44-year-old female patient with classical Guillain-Barré syndrome signs and symptoms on admission, and respiratory signs and symptoms six days prior to the onset of neurological symptoms. There were positive SARS-CoV IgG and IgM blood tests and an epidemiological link of direct contact with people infected with SARS-CoV-2. She required ICU care due to the risk of respiratory failure, along with immunoglobulin treatment, but did not need mechanical ventilation; she improved and was discharged. One month later she consulted again and was thought to have had a Guillain-Barré relapse. She was hospitalized and treated until she progressed and her symptoms resolved. (Acta Med Colomb 2022; 47. DOI:https://doi.org/10.36104/amc.2022.2204).

Resumen El coronavirus tipo 2 es un P-coronavirus cuya infección se caracteriza por clínica de predominio respiratorio; sin embargo, la sintomatologia neurológica está cobrando gran interés asociada a la infección pulmonar e invasión directa del virus al sistema nervioso central. Siendo posible la aso ciación entre el síndrome de Guillain-Barré y la infección por virus SARS-CoV-2. En este reporte se describe dicha asociación en una paciente femenina de 44 años de edad, con clínica clásica de síndrome de Guillain-Barré al ingreso y clínica respiratoria seis días previos a la instalación de los síntomas neurológicos. Reportándose serologías IgG e IgM para SARS-CoV-positivas y nexo epidemiológico de contacto directo con personas infectadas por SARS-CoV-2. Requirió manejo en UCI por riesgo de falla respiratoria, manejo con inmunoglobulinas, sin requerimiento de ventilación mecánica, presentando mejoría y otorgándose salida. Un mes después reconsulta, se considera recaída de Guillain-Barré, se hospitaliza, se inicia manejo hasta evolución y resolución de síntomas. (Acta Med Colomb 2022; 47. DOI:https://doi.org/10.36104/amc.2022.2204).

Drug-like molecules with anti-trypanothione synthetase activity identified by high throughput screening.

Trypanothione synthetase (TryS) catalyses the synthesis of N1,N8-bis(glutathionyl)spermidine (trypanothione), which is the main low molecular mass thiol supporting several redox functions in trypanosomatids. TryS attracts attention as molecular target for drug development against pathogens causing severe and fatal diseases in mammals. A drug discovery campaign aimed to identify and characterise new inhibitors of TryS with promising biological activity was conducted. A large compound library (n = 51,624), most of them bearing drug-like properties, was primarily screened against TryS from Trypanosoma brucei (TbTryS). With a true-hit rate of 0.056%, several of the TbTryS hits (IC50 from 1.2 to 36 µM) also targeted the homologue enzyme from Leishmania infantum and Trypanosoma cruzi (IC50 values from 2.6 to 40 µM). Calmidazolium chloride and Ebselen stand out for their multi-species anti-TryS activity at low µM concentrations (IC50 from 2.6 to 13.8 µM). The moieties carboxy piperidine amide and amide methyl thiazole phenyl were identified as novel TbTryS inhibitor scaffolds. Several of the TryS hits presented one-digit µM EC50 against T. cruzi and L. donovani amastigotes but proved cytotoxic against the human osteosarcoma and macrophage host cells (selectivity index ≤ 3). In contrast, seven hits showed a significantly higher selectivity against T. b. brucei (selectivity index from 11 to 182). Non-invasive redox assays confirmed that Ebselen, a multi-TryS inhibitor, induces an intracellular oxidative milieu in bloodstream T. b. brucei. Kinetic and mass spectrometry analysis revealed that Ebselen is a slow-binding inhibitor that modifies irreversible a highly conserved cysteine residue from the TryS's synthetase domain. The most potent TbTryS inhibitor (a singleton containing an adamantine moiety) exerted a non-covalent, non-competitive (with any of the substrates) inhibition of the enzyme. These data feed the drug discovery pipeline for trypanosomatids with novel and valuable information on chemical entities with drug potential.

A simple, robust, and affordable bioluminescent assay for drug discovery against infective African trypanosomes.

African trypanosomiasis is a major problem for human and animal health in endemic countries, where it threatens millions of people and affects economic development. New drugs are needed to overcome the toxicity, administration, low efficacy, and resistance issues of the current chemotherapy. Robust, simple, and economical high-throughput, whole-cell-based assays are required to accelerate the identification of novel chemical entities. With this aim, we generated a bioluminescent cell line of the bloodstream stage of Trypanosoma brucei brucei and established a screening assay. Trypanosomes were stably transfected to constitutively express a thermostable red-shifted luciferase. The growth phenotype and drug sensitivity of the reporter cell line were essentially identical to that of the parental cell line. The endogenous luciferase activity, measured by a simple bioluminescence assay, proved to be proportional to parasite number and metabolic status. The assay, optimized to detect highly potent compounds in a 96-well-plate format, was validated by screening a small compound library (inter-assay values for Z' factor and coefficient variation were 0.77 and 5.8%, respectively). With a hit-confirmation ratio of ~97%, the assay was potent enough to identify several hits with EC50 ≤ 10 µM. Preliminary tests indicated that the assay can be scaled up to a 384-well-plate format without compromising its robustness. In summary, we have generated reporter trypanosomes and a simple, robust, and affordable bioluminescence screening assay with great potential to speed up the early-phase drug discovery against African trypanosomes.

Nox2-derived superoxide radical is crucial to control acute Trypanosoma cruzi infection.

Trypanosoma cruzi is a flagellated protozoan that undergoes a complex life cycle between hematophagous insects and mammals. In humans, this parasite causes Chagas disease, which in thirty percent of those infected, would result in serious chronic pathologies and even death. Macrophages participate in the first stages of infection, mounting a cytotoxic response which promotes massive oxidative damage to the parasite. On the other hand, T. cruzi is equipped with a robust antioxidant system to repeal the oxidative attack from macrophages. This work was conceived to explicitly assess the role of mammalian cell-derived superoxide radical in a murine model of acute infection by T. cruzi. Macrophages derived from Nox2-deficient (gp91phox-/-) mice produced marginal amounts of superoxide radical and were more susceptible to parasite infection than those derived from wild type (wt) animals. Also, the lack of superoxide radical led to an impairment of parasite differentiation inside gp91phox-/- macrophages. Biochemical or genetic reconstitution of intraphagosomal superoxide radical formation in gp91phox-/- macrophages reverted the lack of control of infection. Along the same line, gp91phox-/- infected mice died shortly after infection. In spite of the higher lethality, parasitemia did not differ between gp91phox-/- and wt animals, recapitulating an observation that has led to conflicting interpretations about the importance of the mammalian oxidative response against T. cruzi. Importantly, gp91phox-/- mice presented higher and disseminated tissue parasitism, as evaluated by both qPCR- and bioimaging-based methodologies. Thus, this work supports that Nox2-derived superoxide radical plays a crucial role to control T. cruzi infection in the early phase of a murine model of Chagas disease.

Ensemble learning application to discover new trypanothione synthetase inhibitors.

Trypanosomatid-caused diseases are among the neglected infectious diseases with the highest disease burden, affecting about 27 million people worldwide and, in particular, socio-economically vulnerable populations. Trypanothione synthetase (TryS) is considered one of the most attractive drug targets within the thiol-polyamine metabolism of typanosomatids, being unique, essential and druggable. Here, we have compiled a dataset of 401 T. brucei TryS inhibitors that includes compounds with inhibitory data reported in the literature, but also in-house acquired data. QSAR classifiers were derived and validated from such dataset, using publicly available and open-source software, thus assuring the portability of the obtained models. The performance and robustness of the resulting models were substantially improved through ensemble learning. The performance of the individual models and the model ensembles was further assessed through retrospective virtual screening campaigns. At last, as an application example, the chosen model-ensemble has been applied in a prospective virtual screening campaign on DrugBank 5.1.6 compound library. All the in-house scripts used in this study are available on request, whereas the dataset has been included as supplementary material.

Automatic ladybird beetle detection using deep-learning models.

Fast and accurate taxonomic identification of invasive trans-located ladybird beetle species is essential to prevent significant impacts on biological communities, ecosystem functions, and agricultural business economics. Therefore, in this work we propose a two-step automatic detector for ladybird beetles in random environment images as the first stage towards an automated classification system. First, an image processing module composed of a saliency map representation, simple linear iterative clustering superpixels segmentation, and active contour methods allowed us to generate bounding boxes with possible ladybird beetles locations within an image. Subsequently, a deep convolutional neural network-based classifier selects only the bounding boxes with ladybird beetles as the final output. This method was validated on a 2, 300 ladybird beetle image data set from Ecuador and Colombia obtained from the iNaturalist project. The proposed approach achieved an accuracy score of 92% and an area under the receiver operating characteristic curve of 0.977 for the bounding box generation and classification tasks. These successful results enable the proposed detector as a valuable tool for helping specialists in the ladybird beetle detection problem.

New Pd-Fe ferrocenyl antiparasitic compounds with bioactive 8-hydroxyquinoline ligands: a comparative study with their Pt-Fe analogues.

In the search for a more effective chemotherapy for the treatment of Human African Trypanosomiasis, a disease caused by the parasite Trypanosoma brucei, the development of ferrocenyl compounds has arisen as a promising strategy. In this work, five new Pd-Fe heterobimetallic [PdII(L)(dppf)](PF6) compounds, including 8-hydroxyquinolyl derivatives HL1-HL5 as bioactive ligands and dppf = 1,1'-bis(diphenylphosphino)ferrocene as the organometallic co-ligand, were synthesized and fully characterized in the solid state and in solution. Molecular structures of three compounds were solved by single crystal X-ray diffraction methods. The compounds displayed submicromolar or micromolar IC50 values against bloodstream T. brucei (IC50: 0.33-1.2 µM), and good selectivity towards the pathogen (SI: 4-102) with respect to mammalian macrophages (cell line J774). The new Pd complexes proved to be 2-fold to 45-fold more potent than the drug nifurtimox but most of them are less active than their Pt analogues. Potential molecular targets were studied. The complexes interact with DNA but they do not alter the intracellular thiol-redox homeostasis of the parasite. In order to understand and predict the main structural determinants on the anti-T. brucei activity, a search of quantitative structure-activity relationships (QSAR) was performed including all the [M(L)(dppf)](PF6) complexes, where M = Pd(ii) or Pt(ii), currently and previously developed by us. The correlation obtained shows the relevance of the electronic effects, the lipophilicity and the type of metal. According to the QSAR study, compounds with electron-withdrawing ligands, higher lipophilicity and harboring Pt would result in higher T. brucei cytotoxicity. From the whole series of [M(L)(dppf)](PF6) compounds developed, where M = Pt(ii) or Pd(ii) and HL = 8-hydroxyquinolyl derivatives, Pt-dppf-L4 (IC50 = 0.14 µM, SI = 48) was selected to perform an exploratory pre-clinical study in infected mice. This hit compound lacks acute toxicity when applied to animals in the dose/regimen described and exerts an anti-proliferative effect on parasites, which extends animal survival but is not curative.

An approach to automatic classification of Culicoides species by learning the wing morphology.

Fast and accurate identification of biting midges is crucial in the study of Culicoides-borne diseases. In this work, we propose a two-stage method for automatically analyzing Culicoides (Diptera: Ceratopogonidae) species. First, an image preprocessing task composed of median and Wiener filters followed by equalization and morphological operations is used to improve the quality of the wing image in order to allow an adequate segmentation of particles of interest. Then, the segmentation of the zones of interest inside the biting midge wing is made using the watershed transform. The proposed method is able to produce optimal feature vectors that help to identify Culicoides species. A database containing wing images of C. obsoletus, C. pusillus, C. foxi, and C. insignis species was used to test its performance. Feature relevance analysis indicated that the mean of hydraulic radius and eccentricity were relevant for the decision boundary between C. obsoletus and C. pusillus species. In contrast, the number of particles and the mean of the hydraulic radius was relevant for deciding between C. foxi and C. insignis species. Meanwhile, for distinguishing among the four species, the number of particles and zones, and the mean of circularity were the most relevant features. The linear discriminant analysis classifier was the best model for the three experimental classification scenarios previously described, achieving averaged areas under the receiver operating characteristic curve of 0.98, 0.90, and 0.96, respectively.