Introducing the NUATEI Consortium: A Mexican Research Program for the Identification of Natural and Synthetic Antimicrobial Compounds for Prevalent Infectious Diseases.

The need for new drugs to treat human infections is a global health concern. Diseases like tuberculosis, trypanosomiasis, amoebiasis, and AIDS remain significant problems, especially in developing countries like Mexico. Despite existing treatments, issues such as resistance and adverse effects drive the search for new alternatives. Herein, we introduce the NUATEI research consortium, made up of experts from the Institute of Biomedical Research at UNAM, who identify and obtain natural and synthetic compounds and test their effects against human pathogens using in vitro and in vivo models. The consortium has evaluated hundreds of natural extracts and compounds against the pathogens causing tuberculosis, trypanosomiasis, amoebiasis, and AIDS, rendering promising results, including a patent with potential for preclinical studies. This paper presents the rationale behind the formation of this consortium, as well as its objectives and strategies, emphasizing the importance of natural and synthetic products as sources of antimicrobial compounds and the relevance of the diseases studied. Finally, we briefly describe the methods of the evaluation of the compounds in each biological model and the main achievements. The potential of the consortium to screen numerous compounds and identify new therapeutic agents is highlighted, demonstrating its significant contribution to addressing these infectious diseases.

Correction to "A Multiscale Study of Phosphorylcholine Driven Cellular Phenotypic Targeting".

[This corrects the article DOI: 10.1021/acscentsci.2c00146.].

An engineered bacterial symbiont allows noninvasive biosensing of the honey bee gut environment.

The honey bee is a powerful model system to probe host-gut microbiota interactions, and an important pollinator species for natural ecosystems and for agriculture. While bacterial biosensors can provide critical insight into the complex interplay occurring between a host and its associated microbiota, the lack of methods to noninvasively sample the gut content, and the limited genetic tools to engineer symbionts, have so far hindered their development in honey bees. Here, we built a versatile molecular tool kit to genetically modify symbionts and reported for the first time in the honey bee a technique to sample their feces. We reprogrammed the native bee gut bacterium Snodgrassella alvi as a biosensor for IPTG, with engineered cells that stably colonize the gut of honey bees and report exposure to the molecules in a dose-dependent manner through the expression of a fluorescent protein. We showed that fluorescence readout can be measured in the gut tissues or noninvasively in the feces. These tools and techniques will enable rapid building of engineered bacteria to answer fundamental questions in host-gut microbiota research.

Effects of systemic oxytocin administration on ultraviolet B-induced nociceptive hypersensitivity and tactile hyposensitivity in mice.

Ultraviolet B (UVB) radiation induces cutaneous inflammation, leading to thermal and mechanical hypersensitivity. Here, we examine the mechanical properties and profile of tactile and nociceptive peripheral afferents functionally disrupted by this injury and the role of oxytocin (OXT) as a modulator of this disruption. We recorded intracellularly from L4 afferents innervating the irradiated area (5.1 J/cm2) in 4-6 old week male mice (C57BL/6J) after administering OXT intraperitoneally, 6 mg/Kg. The distribution of recorded neurons was shifted by UVB radiation to a pattern observed after acute and chronic injuries and reduced mechanical thresholds of A and C- high threshold mechanoreceptors while reducing tactile sensitivity. UVB radiation did not change somatic membrane electrical properties or fiber conduction velocity. OXT systemic administration rapidly reversed these peripheral changes toward normal in both low and high-threshold mechanoreceptors and shifted recorded neuron distribution toward normal. OXT and V1aR receptors were present on the terminals of myelinated and unmyelinated afferents innervating the skin. We conclude that UVB radiation, similar to local tissue surgical injury, cancer metastasis, and peripheral nerve injury, alters the distribution of low and high threshold mechanoreceptors afferents and sensitizes nociceptors while desensitizing tactile units. Acute systemic OXT administration partially returns all of those effects to normal.

A new fluorescent probe for the visualization of progerin.

Hutchinson-Gilford progeria syndrome (HGPS) or progeria is a rare genetic disease that causes premature aging, leading to a drastic reduction in the life expectancy of patients. Progeria is mainly caused by the intracellular accumulation of a defective protein called progerin, generated from a mutation in the LMNA gene. Currently, there is only one approved drug for the treatment of progeria, which has limited efficacy. It is believed that progerin levels are the most important biomarker related to the severity of the disease. However, there is a lack of effective tools to directly visualize progerin in the native cellular models, since the commercially available antibodies are not well suited for the direct visualization of progerin in cells from the mouse model of the disease. In this context, an alternative option for the visualization of a protein relies on the use of fluorescent chemical probes, molecules with affinity and specificity towards a protein. In this work we report the synthesis and characterization of a new fluorescent probe (UCM-23079) that allows for the direct visualization of progerin in cells from the most widely used progeroid mouse model. Thus, UCM-23079 is a new tool compound that could help prioritize potential preclinical therapies towards the final goal of finding a definitive cure for progeria.

Neuroactive metabolites modulated by the gut microbiota in honey bees.

Honey bees have emerged as a new model to study the gut-brain axis, as they exhibit complex social behaviors and cognitive abilities, while experiments with gnotobiotic bees have revealed that their gut microbiota alters both brain and behavioral phenotypes. Furthermore, while honey bee brain functions supporting a broad range of behaviors have been intensively studied for over 50 years, the gut microbiota of bees has been experimentally characterized only recently. Here, we combined six published datasets from metabolomic analyses to provide an overview of the neuroactive metabolites whose abundance in the gut, hemolymph and brain varies in presence of the gut microbiota. Such metabolites may either be produced by gut bacteria, released from the pollen grains during their decomposition by bacteria, or produced by other organs in response to different bacterial products. We describe the current state of knowledge regarding the impact of such metabolites on brain function and behavior and provide further hypotheses to explore in this emerging field of research.

The mechanism of an electrostatic nanofilter: overcoming entropy with electrostatics.

General porins are nature's sieving machinery in the outer membrane of Gram-negative bacteria. Their unique hourglass-shaped architecture is highly conserved among different bacterial membrane proteins and other biological channels. These biological nanopores have been designed to protect the interior of the bacterial cell from leakage of toxic compounds while selectively allowing the entry of the molecules needed for cell growth and function. The mechanism of transport through porins is of utmost and direct interest for drug discovery, extending toward nanotechnology applications for blue energy, separations, and sequencing. Here we present a theoretical framework for analysing the filter of general porins in relation to translocating molecules with the aid of enhanced molecular simulations quantitatively. Using different electrostatic probes in the form of a series of related molecules, we describe the nature of this filter and how to finely tune permeability by exploiting electrostatic interactions between the pore and the translocating molecule. Eventually, we show how enhanced simulations constitute today a valid tool for characterising the mechanism and quantifying energetically the transport of molecules through nanopores.

Structure of the connexin-43 gap junction channel in a putative closed state.

Gap junction channels (GJCs) mediate intercellular communication by connecting two neighbouring cells and enabling direct exchange of ions and small molecules. Cell coupling via connexin-43 (Cx43) GJCs is important in a wide range of cellular processes in health and disease (Churko and Laird, 2013; Liang et al., 2020; Poelzing and Rosenbaum, 2004), yet the structural basis of Cx43 function and regulation has not been determined until now. Here, we describe the structure of a human Cx43 GJC solved by cryo-EM and single particle analysis at 2.26 Å resolution. The pore region of Cx43 GJC features several lipid-like densities per Cx43 monomer, located close to a putative lateral access site at the monomer boundary. We found a previously undescribed conformation on the cytosolic side of the pore, formed by the N-terminal domain and the transmembrane helix 2 of Cx43 and stabilized by a small molecule. Structures of the Cx43 GJC and hemichannels (HCs) in nanodiscs reveal a similar gate arrangement. The features of the Cx43 GJC and HC cryo-EM maps and the channel properties revealed by molecular dynamics simulations suggest that the captured states of Cx43 are consistent with a closed state.

Epidemiología y prevalencia de Mycoplasma genitalium y resistencia a azitromicina en el Área Norte de Tenerife, Islas Canarias / Epidemiology and prevalence of Mycoplasma genitalium and resistance to azithromycin in the North Area of Tenerife, Canary Islands

INTRODUCCIÓN: La infección y resistencia antimicrobiana de Mycoplasma genitalium está infradiagnósticada en nuestra comunidad ya que no es una Enfermedad de Declaración Obligatoria y requiere técnicas de biología molecular, no siempre disponibles. OBJETIVO: Estudiar la epidemiología y prevalencia de M. genitalium y la tasa de resistencia frente a azitromicina en nuestra Área de Salud. MÉTODOS: Estudio retrospectivo, desde abril de 2019 a julio de 2020, realizado en el Área de Salud del Norte de Tenerife, la cual atiende el Hospital Universitario Canarias. Para el diagnóstico de las infecciones de transmisión sexual (ITS) se utilizó la RT-PCR Allplex™ STI Essential Assay (Seegene, South Korea). Las muestras en las que se detectó M. genitalium fueron congeladas a −80°C para posteriormente realizar estudio de resistencia a azitromicina con la RT-PCR Allplex™ MG y AziR Assay (Seegene, South Korea). RESULTADOS: Se identificaron 111/3.849 (prevalencia de 2,8%) pacientes con M. genitalium, de los cuales la mayoría, 59(53,1%) eran hombres con una mediana de 32 años (15-74) y cuyas muestras procedían principalmente de Atención Primaria: 55 (49,5%). Para la detección de resistencia a azitromicina, de los 111 pacientes solo se pudo analizar las muestras de 79, detectándose resistencia in vitro en 15(18,3%): 10 con A2059G, 4 con A2058G y 1 con ambas. La resistencia a azitromicina fue más frecuente en hombres 12 (15,8%). DISCUSIÓN Y CONCLUSIONES: Con este estudio se pone de manifiesto la importancia de la prevalencia de M. genitalium en nuestro entorno, así como su alta tasa de resistencia a azitromicina por lo que se hace necesario vigilar dicha resistencia en nuestro Área de Salud para su adecuado tratamiento.

BACKGROUND: Infection and antimicrobial resistance of Mycoplasma genitalium is under-diagnosed in our community as it is not a Notifiable Infectious Disease and requires for its detection molecular biology techniques, which are not always available. AIM: To study the epidemiology and prevalence of M. genitalium and the rate of resistance to azithromycin in our Health Care Area. METHODS: We conducted a retrospective study from April 2019 to July 2020 in the Northern Health Care Area of Tenerife, which is attended to the Universitary Hospital Complex of the Canary Islands. The RT-PCR Allplex™ STI Essential Assay (Seegene, South Korea) to diagnose Sexually Transmitted Infections (STI) was used. Samples in which M. genitalium was detected were stored at −80°C for subsequent diagnosis of resistance to azithromycin with the RT-PCR Allplex™ MG and AziR Assay (Seegene, South Korea). RESULTS: Of a total of 111/3,849 (2.8% prevalence) patients diagnosed with M. genitalium, 59 (53.1%) were male with a mean age of 30 (19-61) years and mainly from Primary Care 55 (49.5%). Only 79 samples of the 111 patients could be tested to detect azithromycin resistance, of which 15 (18.3%) were resistant in vitro: 10 with A2059G, 4 with A2058G and 1 with both. Azithromycin resistance was more frequent in men 12 (15.8%) and detected mainly in urine samples 6 (60%). Discussion and CONCLUSIONS: This study highlights the prevalence of M. genitalium in our setting as well as the high rate of resistance to azithromycin, making it necessary to detect resistance to azithromycin in M. genitalium for its appropriate treatment in our Health Care Area.

Lactated Ringers Use in the First 24 Hours of Hospitalization Is Associated With Improved Outcomes in 999 Patients With Acute Pancreatitis.

INTRODUCTION: Recent pilot trials in acute pancreatitis (AP) found that lactated ringers (LR) usage may result in decreased risk of moderately severe/severe AP compared with normal saline, but their small sample sizes limit statistical power. We investigated whether LR usage is associated with improved outcomes in AP in an international multicenter prospective study. METHODS: Patients directly admitted with the diagnosis of AP were prospectively enrolled at 22 international sites between 2015 and 2018. Demographics, fluid administration, and AP severity data were collected in a standardized prospective manner to examine the association between LR and AP severity outcomes. Mixed-effects logistic regression analysis was performed to determine the direction and magnitude of the relationship between the type of fluid administered during the first 24 hours and the development of moderately severe/severe AP. RESULTS: Data from 999 patients were analyzed (mean age 51 years, female 52%, moderately severe/severe AP 24%). Usage of LR during the first 24 hours was associated with reduced odds of moderately severe/severe AP (adjusted odds ratio 0.52; P = 0.014) compared with normal saline after adjusting for region of enrollment, etiology, body mass index, and fluid volume and accounting for the variation across centers. Similar results were observed in sensitivity analyses eliminating the effects of admission organ failure, etiology, and excessive total fluid volume. DISCUSSION: LR administration in the first 24 hours of hospitalization was associated with improved AP severity. A large-scale randomized clinical trial is needed to confirm these findings.

Synergy of Plant Essential Oils in Antibiotic Therapy to Combat Klebsiella pneumoniae Infections.

Increased antibiotic resistance presents a health problem worldwide. The World Health Organization published a list of pathogens considered a priority for designing new treatments. Klebsiella pneumoniae (Kp) is a top-priority microorganism, highlighting the strains that produce carbapenemases. Developing new efficient therapies or complementing existing treatments is a priority, and essential oils (EOs) provide an alternative. EOs could act as antibiotic adjuvants and enhance antibiotic activity. Employing standard methodologies, the antibacterial activity of the EOs and their synergic effect with antibiotics were detected. A string test was used to identify the impact of the EOs over the hypermucoviscosity phenotype presented by Kp strains, and Gas Chromatography-Mass Spectrometry analysis identified EOs and the composition of EOs. The potential of EOs for designing synergistic therapies with antibiotics to combat the infection of KPC diseases was demonstrated. In addition, the alteration of the hypermucoviscosity phenotype was shown as the principal mechanism of a synergic action between EOs and antibiotics. The differential composition of the EOs lets us identify some molecules that will be analyzed. Synergic activity of EOs and antibiotics can provide a solid platform for combating multiresistant pathogens that represent a severe health sector problem, such as Kp infections.

Obesity and alcoholic etiology as risk factors for multisystem organ failure in acute pancreatitis: Multinational study.

BACKGROUND: Multisystem organ failure (MSOF) is the most important determinant of mortality in acute pancreatitis (AP). Obesity and alcoholic etiology have been examined as potential risk factors for MSOF, but prior studies have not adequately elucidated their independent effects on the risk of MSOF. OBJECTIVE: We aimed to determine the adjusted effects of body mass index (BMI) and alcoholic etiology on the risk of MSOF in subjects with AP. METHODS: A prospective observational study of 22 centers from 10 countries was conducted. Patients admitted to an APPRENTICE consortium center with AP between August 2015 and January 2018 were enrolled. Multivariable logistic regression was used to estimate the adjusted effects of BMI, etiology, and other relevant covariates on the risk of MSOF. Models were stratified by sex. RESULTS: Among 1544 AP subjects, there was a sex-dependent association between BMI and the risk of MSOF. Increasing BMI was associated with increased odds of MSOF in males (OR 1.10, 95% confidence interval [CI] 1.04-1.15) but not in females (OR 0.98, 95% CI 0.90-1.1). Male subjects with AP, whose BMIs were 30-34 and >35 kg/m2 , had odds ratios of 3.78 (95% CI 1.62-8.83) and 3.44 (95% CI 1.08-9.99), respectively. In females, neither higher grades of obesity nor increasing age increased the risk of MSOF. Alcoholic etiology was independently associated with increased odds of MSOF compared with non-alcohol etiologies (OR 4.17, 95% CI 2.16-8.05). CONCLUSION: Patients with alcoholic etiology and obese men (but not women) are at substantially increased risk of MSOF in AP.

Maturation state of colonization sites promotes symbiotic resiliency in the Euprymna scolopes-Vibrio fischeri partnership.

BACKGROUND: Many animals and plants acquire their coevolved symbiotic partners shortly post-embryonic development. Thus, during embryogenesis, cellular features must be developed that will promote both symbiont colonization of the appropriate tissues, as well as persistence at those sites. While variation in the degree of maturation occurs in newborn tissues, little is unknown about how this variation influences the establishment and persistence of host-microbe associations. RESULTS: The binary symbiosis model, the squid-vibrio (Euprymna scolopes-Vibrio fischeri) system, offers a way to study how an environmental gram-negative bacterium establishes a beneficial, persistent, extracellular colonization of an animal host. Here, we show that bacterial symbionts occupy six different colonization sites in the light-emitting organ of the host that have both distinct morphologies and responses to antibiotic treatment. Vibrio fischeri was most resilient to antibiotic disturbance when contained within the smallest and least mature colonization sites. We show that this variability in crypt development at the time of hatching allows the immature sites to act as a symbiont reservoir that has the potential to reseed the more mature sites in the host organ when they have been cleared by antibiotic treatment. This strategy may produce an ecologically significant resiliency to the association. CONCLUSIONS: The data presented here provide evidence that the evolution of the squid-vibrio association has been selected for a nascent organ with a range of host tissue maturity at the onset of symbiosis. The resulting variation in physical and chemical environments results in a spectrum of host-symbiont interactions, notably, variation in susceptibility to environmental disturbance. This "insurance policy" provides resiliency to the symbiosis during the critical period of its early development. While differences in tissue maturity at birth have been documented in other animals, such as along the infant gut tract of mammals, the impact of this variation on host-microbiome interactions has not been studied. Because a wide variety of symbiosis characters are highly conserved over animal evolution, studies of the squid-vibrio association have the promise of providing insights into basic strategies that ensure successful bacterial passage between hosts in horizontally transmitted symbioses. Video Abstract.

New Pharmacological Approaches for Rare Diseases.

The expression "rare disease" describes a group of diseases whose individual prevalence is low (between 3.9 and 6.6 in 10,000 subjects depending on the country) but which in total affect up to the 3-6% of the worldwide population [...].

How the physical properties of bacterial porins match environmental conditions.

Transmembrane ß-barrel proteins are key systems for transport phenomena in biology. Based on their broad substrate specificity, they represent good candidates for present and future technological applications, such as DNA/RNA and protein sequencing, sensing of biomedical analytes, and production of blue energy. For a better understanding of the process at the molecular level, we applied parallel tempering simulations in the WTE ensemble to compare two ß-barrel porins from Escherichia coli, OmpF and OmpC. Our analysis showed a different behavior of the two highly homologous porins, where subtle amino acid substitutions can modulate critical properties of mass transport. Interestingly, the differences can be mapped to the respective environmental conditions under which the two porins are expressed. Apart from reporting on the advantages of the enhanced sampling methods in assessing the molecular properties of nanopores, our comparative analysis provided new and key results to better understand biological function and technical applications. Eventually, we showed how results from molecular simulations align well with experimental single-channel measurements, thus demonstrating the mature evolution of numerical methodologies for predicting properties in this field crucial for future biomedical applications.

Use of intraoperative ultrasound to improve tension-free vaginal tape-obturator placement: A pilot study.

OBJECTIVE: To evaluate the use of intraoperative ultrasound (IUS) to achieve a postoperative optimal placement of the tension-free vaginal tape-obturator (TVT-O). METHODS: A cohort study was performed among women who underwent TVT-O placement. In 25 women, ultrasound was used for the placement, and based on current evidence, the optimal intraoperative and postoperative ultrasound pattern was selected. They were compared with 25 women where IUS was not used. RESULTS: IUS increased operative time (by 7.5 min), and in 36% (9/25) of cases it was necessary to perform some corrections based on the ultrasound findings. After 1 month, in patients of the IUS group, the tapes were more frequently placed at a distance of 3-5 mm (P = 0.01), and it was more common for it to be placed between 40% and 70% relative to the urethral length (P = 0.011). Of tapes placed with IUS, 76% (met the optimal postoperative ultrasound pattern, as opposed to only 48% placed without IUS (P = 0.041). No differences were found in the complications or the functional results at 1 month post-surgery. CONCLUSION: The use of IUS for the placement of TVT-O allows us to position them optimally and avoid erroneous placements, although IUS increases the operative time without improving the functional results and the rate of complications.

Differential Strain-dependent Ovarian and Metabolic Responses in a Mouse Model of PCOS.

Several mouse models have been developed to study polycystic ovarian syndrome (PCOS), a leading cause of infertility in women. Treatment of mice with DHT for 90 days causes ovarian and metabolic phenotypes similar to women with PCOS. We used this 90-day DHT treatment paradigm to investigate the variable incidence and heterogeneity in 2 inbred mouse strains, NOD/ShiLtJ and 129S1/SvlmJ. NOD mice naturally develop type 1 diabetes, and recent meta-analysis found increased androgen excess and PCOS in women with type 1 diabetes. The 129S1 mice are commonly used in genetic manipulations. Both NOD and 129S1 DHT-treated mice had early vaginal opening, increased anogenital distance, and altered estrus cycles compared with control animals. Additionally, both NOD and 129S1 mice had reduced numbers of corpora lutea after DHT exposure, whereas NOD mice had decreased numbers of preantral follicles and 129S1 mice had reduced numbers of small antral follicles. NOD mice had increased body weight, decreased white adipocyte size, and improved glucose sensitivity in response to DHT, whereas 129S1 mice had increased body weight and white adipocyte size. NOD mice had increased expression of Adiponectin, Cidea, Srebp1a, and Srebp1b and 129S1 mice had decreased Pparg in the white adipose tissues, whereas both NOD and 129S1 mice had increased expression of Glut4 and Prdm16, suggesting DHT may differentially affect glucose transport, thermogenesis, and lipid storage in white adipose tissue. DHT causes different ovarian and metabolic responses in NOD and 129S1 mice, suggesting that strain differences may allow further elucidation of genetic contributions to PCOS.

Five centuries of Cirsium ehrenbergii Sch. Bip. (Asteraceae) in Mexico, from Huitzquilitl to Cardo Santo: History, ethnomedicine, pharmacology and chemistry.

ETHNOPHARMACOLOGICAL RELEVANCE: Several medicinal plants, including the endemic herb Cirsum ehrenbergii (Asteraceae), have been documented in manuscripts, medical and botanical books written in Mexico since the XVI century until the present. This unique circumstance is a real window in the time that allows to investigate historical and contemporary ethnopharmacological knowledge. AIM OF THE STUDY: To examine the persistence, disappearance, and transformation of ethnomedicinal knowledge of C. ehrenbergii along time. Also, to investigate the chemistry and pharmacology of this species in relation to its historical and present day main ethnomedical applications related to Central Nervous System and inflammation. MATERIALS AND METHODS: A thorough review was performed of written sources of medicinal plants from XVI and onwards. For the pharmacological studies, the organic extracts were tested in mice models to assess its antidepressant and anti-inflammatory properties. The active extracts were studied chemically. The isolated compounds were identified by 1H, 13C NMR, or characterized by GC-MS. RESULTS: Cirsum ehrenbergii was illustrated for the first time (1552) in the Libellus de Medicinalibus Indorum Herbis (Booklet of Medicinal Plants of the Indians) and named in the Nahuatl native language as huitzquilitl (edible thistle). It was there recommended as nigris sanguinis remedium (remedy for black blood), and for the treatment of illnesses with an inflammatory component. Nigris sanguinis was well known in the European medicine of that time and currently it has been interpreted as "depression". At the present time, peasants and native population in Mexico mainly name C. ehrenbergii in Spanish as cardo Santo (holy thistle). Its original Nahuatl name has been almost forgotten. However, these communities use this species, among other maladies, to heal "nervios" (anxiety and/or depression) and for anti-inflammatory purposes. These ailments and treatments resemble those recorded in the Libellus and in several medicinal plant books along centuries. The ethanol extract of C. ehrenbergii roots showed antidepressant-like activity in mice administered at 300 mg/kg, as indicated by the forced swim test (FST). The glycosylated flavonoid linarin was identified as antidepressant principle and was active at the doses of 30 and 60 mg/kg in the FST. Regarding to anti-inflammatory activity, the most active was the methylene chloride extract of the aerial parts, which contains taraxasterol, pseudotaraxasterol, ß-sitosterol and stigmasterol. CONCLUSIONS: Cirsium ehrenbergii extracts possess antidepressant-like (roots, EtOH) and anti-inflammatory (aerial parts, CH2Cl2) properties, containing active compounds. Our results sustain historical and present day ethnomedical applications of this species documented along five centuries.

Potent Anti-amoebic Effects of Ibogaine, Voacangine and the Root Bark Alkaloid Fraction of Tabernaemontana arborea.

Plants of Tabernaemontana species have several pharmacological activities including antimicrobial effects. Amoebiasis continues to be a public health problem, with increasing evidence of resistance to metronidazole. In this study, we assessed the effect of the alkaloid fraction of T. arborea root bark and the alkaloids ibogaine and voacangine on the viability and infectivity of Entamoeba histolytica trophozoites. Cultures were exposed to 0.1 - 10 µg/mL for 24, 48 and 72 h, and viability was then determined using a tetrazolium dye reduction assay and type of cellular death analyzed by flow cytometry. Results showed that the alkaloid fraction, but mainly ibogaine and voacangine alkaloids, exhibited potent dose-dependent anti-amoebic activity at 24 h post-exposure (IC50 4.5 and 8.1 µM, respectively), comparable to metronidazole (IC50 6.8 µM). However, the effect decreased after 48 and 72 h of exposure to concentrations below 10 µg/mL, suggesting that the alkaloids probably were catabolized to less active derivatives by the trophozoites. The treatment of trophozoites with the IC50 s for 24 h induced significant morphological changes in the trophozoites, slight increase in granularity, and death by apoptonecrosis. The capacity of T. arborea alkaloids to inhibit the development of amoebic liver abscesses in hamsters was evaluated. Results showed that even when the treatments reduced the number of amoebic trophozoites in tissue sections of livers, they were unable to limit the formation of abscesses, suggesting their rapid processing to inactive metabolites. This work leaves open the possibility of using Tabernaemontana alkaloids as a new alternative for amoebiasis control.

The Role of Host Cell Glycans on Virus Infectivity: The SARS-CoV-2 Case.

Glycans are ubiquitously expressed sugars, coating the cell and protein surfaces. They are found on many proteins as either short and branched chains or long chains sticking out from special membrane proteins, known as proteoglycans. This sugar cushion, the glycocalyx, modulates specific interactions and protects the cell. Here it is shown that both the expression of proteoglycans and the glycans expressed on the surface of both the host and virus proteins have a critical role in modulating viral attachment to the cell. A mathematical model using SARS-Cov-2 as an archetypical virus to study the glycan role during infection is proposed. It is shown that this occurs via a tug-of-war of forces. On one side, the multivalent molecular recognition that viral proteins have toward specific host glycans and receptors. On the other side, the glycan steric repulsion that a virus must overcome to approach such specific receptors. By balancing both interactions, viral tropism can be predicted. In other words, the authors can map out the cells susceptible to virus infection in terms of receptors and proteoglycans compositions.