Resilience to structural and molecular changes in excitatory synapses in the hippocampus contributes to cognitive function recovery in Tg2576 mice

JOURNAL/nrgr/04.03/01300535-202409000-00040/figure1/v/2024-01-16T170235Z/r/image-tiff Plaques of amyloid-β (Aβ) and neurofibrillary tangles are the main pathological characteristics of Alzheimer's disease (AD). However, some older adult people with AD pathological hallmarks can retain cognitive function. Unraveling the factors that lead to this cognitive resilience to AD offers promising prospects for identifying new therapeutic targets. Our hypothesis focuses on the contribution of resilience to changes in excitatory synapses at the structural and molecular levels, which may underlie healthy cognitive performance in aged AD animals. Utilizing the Morris Water Maze test, we selected resilient (asymptomatic) and cognitively impaired aged Tg2576 mice. While the enzyme-linked immunosorbent assay showed similar levels of Aβ42 in both experimental groups, western blot analysis revealed differences in tau pathology in the pre-synaptic supernatant fraction. To further investigate the density of synapses in the hippocampus of 16-18 month-old Tg2576 mice, we employed stereological and electron microscopic methods. Our findings indicated a decrease in the density of excitatory synapses in the stratum radiatum of the hippocampal CA1 in cognitively impaired Tg2576 mice compared with age-matched resilient Tg2576 and non-transgenic controls. Intriguingly, through quantitative immunoelectron microscopy in the hippocampus of impaired and resilient Tg2576 transgenic AD mice, we uncovered differences in the subcellular localization of glutamate receptors. Specifically, the density of GluA1, GluA2/3, and mGlu5 in spines and dendritic shafts of CA1 pyramidal cells in impaired Tg2576 mice was significantly reduced compared with age-matched resilient Tg2576 and non-transgenic controls. Notably, the density of GluA2/3 in resilient Tg2576 mice was significantly increased in spines but not in dendritic shafts compared with impaired Tg2576 and non-transgenic mice. These subcellular findings strongly support the hypothesis that dendritic spine plasticity and synaptic machinery in the hippocampus play crucial roles in the mechanisms of cognitive resilience in Tg2576 mice.

An assessment of the owned canine and feline demographics in Chile: registration, sterilization, and unsupervised roaming indicators

The global rise in companion animal populations, particularly dogs and cats, is driven by emotional and social benefits for owners, and their population management is becoming critically important to avoid a plethora of adverse effects on themselves, humans, and wildlife. We estimated the size and density of the owned canine and feline population in Chile and evaluated the status of microchipping, registration, sterilization rates, and the proportion of owned animals that roam unsupervised. A cross-sectional household survey in 36 districts was conducted and standard inferential statistics was employed to analyze differences between cats and dogs, sexes within each species, and between rural and urban areas. Additionally, two negative binomial models with mixed effects were developed to predict the number of dogs and cats per households. Two methods were used to compare population size estimates at the country level, multiplying: (1) the estimated mean number of companion animals per household by the estimated number of households at the country level, and (2) the estimated human:dog and human:cat ratios by the total human population. The study involved 6333 respondents, of which 76% (74% urban; 83% rural) owned companion animals (dogs and/or cats). Individuals in rural multi-person households increase the probability of owning dogs and/or cats. Additionally, women exhibit a greater inclination towards cat and dog ownership compared to men, while those over 30 years old demonstrate lower rates of companion animal ownership in contrast to the 18-30 age group for both species. The overall human:dog and human:cat ratios estimated were 2.7:1, and 6.2:1, respectively. The estimated total number of owned dogs and cats in Chile ranged from 9.6 to 10.7 million, depending on the methodological approach, while national median density of companion animals was 12 dogs per km2 (ranging from 0.02 to 7232) and 5 cats per km2 (ranging from 0.01 to 3242). This nationwide study showed one of the highest percentages of households with companion animals in Latin America and relatively low registration and sterilization rates, highlighting the need to strength long-term public policies to control populations of companion animals and promote responsibility in pet ownership.

Environmental DNA reveals temporal variation in mesophotic reefs of the Humboldt upwelling ecosystems of central Chile: Toward a baseline for biodiversity monitoring of unexplored marine habitats

Temperate mesophotic reef ecosystems (TMREs) are among the least known marine habitats. Information on their diversity and ecology is geographically and temporally scarce, especially in highly productive large upwelling ecosystems. Lack of information remains an obstacle to understanding the importance of TMREs as habitats, biodiversity reservoirs and their connections with better-studied shallow reefs. Here, we use environmental DNA (eDNA) from water samples to characterize the community composition of TMREs on the central Chilean coast, generating the first baseline for monitoring the biodiversity of these habitats. We analyzed samples from two depths (30 and 60 m) over four seasons (spring, summer, autumn, and winter) and at two locations approximately 16 km apart. We used a panel of three metabarcodes, two that target all eukaryotes (18S rRNA and mitochondrial COI) and one specifically targeting fishes (16S rRNA). All panels combined encompassed eDNA assigned to 42 phyla, 90 classes, 237 orders, and 402 families. The highest family richness was found for the phyla Arthropoda, Bacillariophyta, and Chordata. Overall, family richness was similar between depths but decreased during summer, a pattern consistent at both locations. Our results indicate that the structure (composition) of the mesophotic communities varied predominantly with seasons. We analyzed further the better-resolved fish assemblage and compared eDNA with other visual methods at the same locations and depths. We recovered eDNA from 19 genera of fish, six of these have also been observed on towed underwater videos, while 13 were unique to eDNA. We discuss the potential drivers of seasonal differences in community composition and richness. Our results suggest that eDNA can provide valuable insights for monitoring TMRE communities but highlight the necessity of completing reference DNA databases available for this region.

Generation of a novel three-dimensional scaffold-based model of the bovine endometrium

Bovine in vitro endometrial models that resemble tissue function in vivo are needed to study infertility, long-term uterine alterations induced by pathogens and impact of endocrine disruptor chemicals on reproductive function and other reproductive system complications that cause high economic losses in livestock species. The present study aimed to generate an innovative, reproducible, and functional 3D scaffold-based model of the bovine endometrium structurally robust for long term-culture. We developed a multicellular model containing both endometrial epithelial and stromal cells. Epithelial cells organized to form a luminal-like epithelial layer on the surface of the scaffold. Stromal cells produced their own extracellular matrix forming a stable subepithelial compartment that physiologically resembles the normal endometrium. Both cell types released prostaglandin E2 and prostaglandin F2α following a treatment with oxytocin and arachidonic acid. Additionally signal pathways mediating oxytocin and arachidonic acid stimulation of prostaglandin synthesis were analyzed by real time PCR (RT-PCR). Oxytocin receptor (OXTR), prostaglandin E2 receptor 2 (EP2), prostaglandin E2 receptor 4 (EP4), prostaglandin F receptor (PTGFR), prostaglandin E synthase (PTGES), PGF-synthase (PGFS) and prostaglandin-endoperoxide synthase 2 (COX-2) expression was detected in both control and treatment groups, however, only significant changes in abundance of OXTR mRNA transcripts were found. The results obtained by this study are a step forward in bovine in vitro culture technology. This 3D scaffold-based model provides a platform to study regulatory mechanisms involved in endometrial physiology and can set the basis for a broader tool for designing and testing novel therapeutic strategies for recurrent uterine pathologies.

Midbrain and pons MRI shape analysis and its clinical and CSF correlates in degenerative parkinsonisms: a pilot study

OBJECTIVES

To conduct brainstem MRI shape analysis across neurodegenerative parkinsonisms and control subjects (CS), along with its association with clinical and cerebrospinal fluid (CSF) correlates.

METHODOLOGY

We collected demographic and clinical variables, performed planimetric and shape MRI analyses, and determined CSF neurofilament-light chain (NfL) levels in 84 participants: 11 CS, 12 with Parkinson's disease (PD), 26 with multiple system atrophy (MSA), 21 with progressive supranuclear palsy (PSP), and 14 with corticobasal degeneration (CBD).

RESULTS

MSA featured the most extensive and significant brainstem shape narrowing (that is, atrophy), mostly in the pons. CBD presented local atrophy in several small areas in the pons and midbrain compared to PD and CS. PSP presented local atrophy in small areas in the posterior and upper midbrain as well as the rostral pons compared to MSA. Our findings of planimetric MRI measurements and CSF NfL levels replicated those from previous literature. Brainstem shape atrophy correlated with worse motor state in all parkinsonisms and with higher NfL levels in MSA, PSP, and PD.

CONCLUSION

Atypical parkinsonisms present different brainstem shape patterns which correlate with clinical severity and neuronal degeneration. In MSA, shape analysis could be further explored as a potential diagnostic biomarker. By contrast, shape analysis appears to have a rather limited discriminant value in PSP.

KEY POINTS

• Atypical parkinsonisms present different brainstem shape patterns. • Shape patterns correlate with clinical severity and neuronal degeneration. • In MSA, shape analysis could be further explored as a potential diagnostic biomarker.

Identification of Secondary Prevention Patients Eligible for PCSK9 Inhibitors Therapy According to the Routine Clinical Practice in Spain

INTRODUCTION

Many patients at very high risk of cardiovascular (CV) events would benefit from lipid-lowering therapies (LLT) intensification to decrease their risk. This study aimed to identify the real-world secondary prevention patients potentially eligible for proprotein convertase subtilisin-kexin type 9 inhibitors (PCSK9i) in Spain.

METHODS

This retrospective cohort study included adult patients registered in the IQVIA Spanish Electronic Medical Records outpatient database (2014-2020), diagnosed with myocardial infarction (MI), unstable angina (UA), ischaemic stroke (IS), transient ischaemic attack (TIA) or peripheral artery disease (PAD) and with ≥ 1 low-density lipoprotein cholesterol (LDL-C) or total cholesterol measurements. Longitudinal data were collected from the initial diagnosis to the end of the study period or follow-up loss.

RESULTS

The study included 9516 patients, 63.9% male, mean (SD) age 67.7 (12.5) years and mean LDL-C 117.3 (38.8) mg/dL. MI, IS and PAD were the most severe events reported during the study period (28.5%, 18.7% and 29.3% of patients, respectively). At the time of last available LDL-C assessment (≥ 3 months post-event), 64.4% patients were on LLT. Of those, 45.4%, 46.9% and 7.7% were on high-, moderate- and low-intensity LLT. Overall, 9.6% patients achieved LDL-C < 55 mg/dL (24.2% LDL-C < 70 mg/dL). Furthermore, 17.9% patients receiving optimized oral LLT showed LDL-C > 100 mg/dL (LDL-C reimbursement threshold for PCSK9i in Spain).

CONCLUSION

Up to 82% of patients with atherosclerotic CV disease do not achieve LDL-C levels recommended by the 2019 ESC/EAS guidelines despite being on optimized oral LLT therapy. In 17.9% of these patients LDL-C levels exceed 100 mg/dL, being eligible for PCSK9i in Spain.

Recalculating the staff required to run a modern assisted reproductive technology laboratory

STUDY QUESTION

What number of staff is sufficient to perform increasingly complicated processes in today's modern ART laboratories?

SUMMARY ANSWER

The adequate number of personnel required for the efficient and safe operation of modern ART laboratories needs to be calculated.

WHAT IS KNOWN ALREADY

In today's modern ART laboratories, the amount of time required to perform increasingly complicated processes has more than doubled, with a downward trend in the amount of work an embryologist can do. Different workload unit values have been used to evaluate each workload task and efficiency in a particular ART laboratory, as well as to occasionally compare one laboratory with another.

STUDY DESIGN, SIZE, DURATION

Seven senior embryologists working at different IVF centers, three public and four private centers, participated in this multicenter study conducted between 2019 and 2020. We prepared a survey to create a calculator for staff using the average (of three attempts) time spent in every laboratory by each embryologist of the center to perform any ART process.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Different laboratory processes and activities related to quality control, time spent and conventional human double witnessing were included in the survey. To calculate the number of processes that each embryologist can perform per year, an embryologist was considered to be having a full-time contract and working 7 or 8 h/day. The times included in the calculation of each task were those corresponding to the 95th percentile. For the calculations, Microsoft® Office Excel® Professional Plus 2019 was used.

MAIN RESULTS AND THE ROLE OF CHANCE

The survey showed that the time needed per embryologist to perform the different processes necessary for a classic IVF cycle without time lapse (TL) was 8.11 h, and with TL, it was 10.27 h. The calculated time also considered the time spent in documentation handling, cycle preparation, database management and conventional human double witnessing verification. An ICSI without TL needed 8.55 h, and with TL, it needed 10.71 h. An ICSI-PGT without a TL cycle needed 11.75 h, and with TL, it needed 13.91 h. Furthermore, 1.81 h should be added for every vitrification support needed. The time needed to control more than 200 critical steps, including equipment control and culture parameters, was 30 min per day plus 3.9 min per device to control.The time spent in semen analysis (including documentation handling, cycle preparation and database management) or intrauterine insemination with a partner sperm was 2.7 h. For donor sperm, an additional hour was required for the management involved. The time required to perform a testicular biopsy and cryopreserve the sample was 4 h. Similarly, the time required to perform seminal cryopreservation was 3.7 h.

LIMITATIONS, REASONS FOR CAUTION

The study was conducted considering a full-time contract embryologist working 7 or 8 h/day, 5 days a week, with days off according to the Spanish regulations. However, our findings can be adapted to foreign regulations using the developed online calculation platform.

WIDER IMPLICATIONS OF THE FINDINGS

A new advanced staff calculator allows any IVF laboratory to estimate the minimum number of embryologists necessary without compromising the security or success of the results. Nevertheless, we recommend a minimum of two qualified embryologists in every laboratory, regardless of the workload.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the Asociación para el Estudio de la Biología de la Reproducción (ASEBIR). None of the authors has any conflict of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Prolactin Reduces Hippocampal Parvalbumin and GABAA Receptor Expression in Female Mice

INTRODUCTION

Parvalbumin (PV)-positive cells are strategic elements of neuronal networks capable of influencing memory and learning processes. However, it is not known whether pituitary hormones may be related to PV expression in the hippocampus - a part of the limbic system with important functions in learning and memory.

OBJECTIVE

Since previous studies indicate that prolactin (PRL) plays a significant role in hippocampal-dependent learning and synaptic plasticity, we hypothesized that a rise in PRL levels can modify PV expression in the hippocampus.

METHODS

We employed biochemical, immunohistochemistry, and densitometry techniques - as well as a behavioural assay - in a hyperprolactinemia model using subcutaneous osmotic pumps in female mice.

RESULTS

PRL treatment via osmotic pump induced an increase in PRL receptor (PRLR) expression in most regions of the hippocampus analysed by Western blotting and immunohistochemistry methods. Fluorescent densitometry analysis revealed that PV expression decreases in the same layers in the hippocampus following PRL treatment, while double labelling immunostaining indicated close localization of PV and PRLR in PV-positive interneurons. In addition, we found that PRL induced a reduction in the β2/3 subunit of GABAA receptor (GABAAR) expression that was linearly correlated with the reduction in PV expression. This reduction in the β2/3 subunit of GABAAR expression was maintained in trained animals in which PRL treatment improved the learning of a spatial memory task.

CONCLUSIONS

These data show, for the first time, that an increase in PRL level is associated with changes in key constituent elements of inhibitory circuits in the hippocampus and may be of relevance for the alterations in cognitive function reported in hyperprolactinemia.

P–161 Is enough the staff in your lab?

Study question

Must be all the activity made in in vitro fertilization (IVF) laboratories keep in mind to size its staff?

Summary answer

To create a staff calculator based on number of cycles carry on, assisted reproduction techniques, quality controls, administration management, weekend duties, labour regulations and holidays.

What is known already

In a bibliographic search about staff in human reproduction labs there is no mention about de number of embryologists recommended for every cycle done. Only that it will be according to the workload. Other guidelines establish that every embryologist could assume 150 IVF cycles/year. However, here is a downward tendency in the work that an embryologist can assume. Alikani established a maximum of 100 cycles/year for every embryologist (Alikani et al, 2014).

Study design, size, duration

Seven senior embryologists working in different IVF centres, three public and 4 privates, take part lead in this Multicentre study during 2019 and 2020. We made a survey to create a calculator for staff using the mean time spent in every lab by each embryologist of the centre to do any IVF procedure and measured three times each one.

Participants/materials, setting, methods

Different lab procedures and activities related with quality control, time spent to do them, and witnessing were included in the survey. For the calculations it was considered an embryologist with a full-time contract working 1744 hours / year according to current labour agreement in Spain.

The times included in the calculations for each task were those corresponding to the 95th percentile. For the calculation, the program used was Microsoft Office Excel.

Main results and the role of chance

In the IVF laboratory many gametes and embryos from different couples are manipulated daily. The maintenance of traceability could be affected by not having the right staff and lead to dramatic consequences for the patients and the centre.

Workload or overload caused by non-suitable staff number also affects the embryologist having a direct impact on his health.

The results of the survey carried out showed the time needed by embryologist to perform the different procedures necessary for an IVF treatment, being a classic IVF cycle (8.11 hours), also taking into account the time spent in managing documentation, preparing the cycle and databases. An ICSI with Time lapse needs 10.27 hours and an ICSI-PGD cycle 13.91 hours. To all off this, 1.81 hours should be added for every vitrification support needed and the time to control more than 200 critical steps, including equipment control and culture parameters.

The time spent in semen analysis (including managing documentation, cycle preparation and databases) or intrauterine insemination with a partner sperm was 2.7 hours. For donor sperm an additional hour for the management involved is required. The time required to perform and cryopreserve a testicular biopsy and seminal cryopreservation was 4 and 3.7 hours, respectively.

Limitations, reasons for caution

The study was made taking account of Spanish regulations, quality standards and recommendations and should be adapted to the foreigner’s regulations. Wider implications of the findings: New advance staff calculator allows laboratories estimate minimum number of embryologist necessary for a particular public or private laboratory without compromise neither security nor success in their results. Nevertheless, we recommended a minimum of two qualified embryologists in every lab, whatever it was the workload.

Trial registration number

none

Nanocomposite Materials with Poly(l-lactic Acid) and Transition-Metal Dichalcogenide Nanosheets 2D-TMDCs WS2

Layered transition-metal dichalcogenides (TMDCs) based on tungsten disulfide nanosheets (2D-WS2) were introduced via melt processing into poly(l-lactic acid) (PLLA) to generate PLLA/2D-WS2 nanocomposite materials. The effects of the 2D-WS2 on the morphology, crystallization, and biodegradation behavior of PLLA were investigated. In particular, the non-isothermal melt-crystallization of neat PLLA and PLLA/2D-WS2 nanocomposites were analyzed in detail by varying both the cooling rate and 2D-WS2 loading. The kinetic parameters of PLLA chain crystallization are successfully described using the Liu model. It was found that the PLLA crystallization rate was reduced with 2D-WS2 incorporation, while the crystallization mechanism and crystal structure of PLLA remained unchanged in spite of nanoparticle loading. This was due to the PLLA chains not being able to easily adsorb on the WS2 nanosheets, hindering crystal growth. In addition, from surface morphology analysis, it was observed that the addition of 2D-WS2 facilitated the enzymatic degradation of poorly biodegradable PLLA using a promising strain of actinobacteria, Lentzea waywayandensis. The identification of more suitable enzymes to break down PLLA nanocomposites will open up new avenues of investigation and development, and it will also lead to more environmentally friendly, safer, and economic routes for bioplastic waste management.

On the generation of periodic discrete structures with identical two-point correlation

Strategies for the generation of periodic discrete structures with identical two-point correlation-called 2PC-equivalent-are developed. It is shown that starting from a set of 2PC-equivalent root structures, 2PC-equivalent child structures of arbitrary resolution and number of phases (e.g. material phases) can be generated based on phase extension through trivial embeddings, kernel-based extension and phase coalescence. Proofs are provided by means of discrete Fourier transform theory. A Python 3 implementation is offered for reproduction of examples and future applications.

Integration of biophysical connectivity in the spatial optimization of coastal ecosystem services

Ecological connectivity in coastal oceanic waters is mediated by dispersion of the early life stages of marine organisms and conditions the structure of biological communities and the provision of ecosystem services. Integrated management strategies aimed at ensuring long-term service provision to society do not currently consider the importance of dispersal and larval connectivity. A spatial optimization model is introduced to maximise the potential provision of ecosystem services in coastal areas by accounting for the role of dispersal and larval connectivity. The approach combines a validated coastal circulation model that reproduces realistic patterns of larval transport along the coast, which ultimately conditions the biological connectivity and productivity of an area, with additional spatial layers describing potential ecosystem services. The spatial optimization exercise was tested along the coast of Central Chile, a highly productive area dominated by the Humboldt Current. Results show it is unnecessary to relocate existing management areas, as increasing no-take areas by 10% could maximise ecosystem service provision, while improving the spatial representativeness of protected areas and minimizing social conflicts. The location of protected areas was underrepresented in some sections of the study domain, principally due to the restriction of the model to rocky subtidal habitats. Future model developments should encompass the diversity of coastal ecosystems and human activities to inform integrative spatial management. Nevertheless, the spatial optimization model is innovative not only for its integrated ecosystem perspective, but also because it demonstrates that it is possible to incorporate time-varying biophysical connectivity within the optimization problem, thereby linking the dynamics of exploited populations produced by the spatial management regime.

The SARS-CoV-2 Ivermectin Navarra-ISGlobal Trial (SAINT) to Evaluate the Potential of Ivermectin to Reduce COVID-19 Transmission in low risk, non-severe COVID-19 patients in the first 48 hours after symptoms onset: A structured summary of a study protocol for a randomized control pilot trial

Objectives

The primary objective is to determine the efficacy of a single dose of ivermectin, administered to low risk, non-severe COVID-19 patients in the first 48 hours after symptom onset to reduce the proportion of patients with detectable SARS-CoV-2 RNA by Polymerase Chain Reaction (PCR) test from nasopharyngeal swab at day 7 post-treatment.

The secondary objectives are:

To assess the efficacy of ivermectin to reduce the SARS-CoV-2 viral load in the nasopharyngeal swab at day 7 post treatment.

To assess the efficacy of ivermectin to improve symptom progression in treated patients.

To assess the proportion of seroconversions in treated patients at day 21.

To assess the safety of ivermectin at the proposed dose.

To determine the magnitude of immune response against SARS-CoV-2.

To assess the early kinetics of immunity against SARS-CoV-2.

Trial design

SAINT is a single centre, double-blind, randomized, placebo-controlled, superiority trial with two parallel arms. Participants will be randomized to receive a single dose of 400 μg/kg ivermectin or placebo, and the number of patients in the treatment and placebo groups will be the same (1:1 ratio).

Participants

The population for the study will be patients with a positive nasopharyngeal swab PCR test for SARS-CoV-2, with non-severe COVID-19 disease, and no risk factors for progression to severity. Vulnerable populations such as pregnant women, minors (i.e.; under 18 years old), and seniors (i.e.; over 60 years old) will be excluded.

Inclusion criteria

Patients diagnosed with COVID-19 in the emergency room of the Clínica Universidad de Navarra (CUN) with a positive SARS-CoV-2 PCR.

Residents of the Pamplona basin (“Cuenca de Pamplona”).

The patient must be between the ages of 18 and 60 years of age.

Negative pregnancy test for women of child bearing age*.

The patient or his/her representative, has given informed consent to participate in the study.

The patient should, in the PI's opinion, be able to comply with all the requirements of the clinical trial (including home follow up during isolation).

Exclusion criteria

Known history of ivermectin allergy.

Hypersensitivity to any component of ivermectin.

COVID-19 pneumonia.

Diagnosed by the attending physician.

Identified in a chest X-ray.

Fever or cough present for more than 48 hours.

Positive IgG against SARS-CoV-2 by rapid diagnostic test.

Age under 18 or over 60 years.

The following co-morbidities (or any other disease that might interfere with the study in the eyes of the PI):

Immunosuppression.

Chronic Obstructive Pulmonary Disease.

Diabetes.

Hypertension.

Obesity.

Acute or chronic renal failure.

History of coronary disease.

History of cerebrovascular disease.

Current neoplasm.

Recent travel history to countries that are endemic for Loa loa (Angola, Cameroon, Central African Republic, Chad, Democratic Republic of Congo, Ethiopia, Equatorial, Guinea, Gabon, Republic of Congo, Nigeria and Sudan).

Current use of CYP 3A4 or P-gp inhibitor drugs such as quinidine, amiodarone, diltiazem, spironolactone, verapamil, clarithromycin, erythromycin, itraconazole, ketoconazole, cyclosporine, tacrolimus, indinavir, ritonavir or cobicistat. Use of critical CYP3A4 substrate drugs such as warfarin.

*Women of child bearing age may participate if they use a safe contraceptive method for the entire period of the study and at least one month afterwards. A woman is considered to not have childbearing capacity if she is post-menopausal (minimum of 2 years without menstruation) or has undergone surgical sterilization (at least one month before the study).

The trial is currently planned at a single center, Clínica Universidad de Navarra, in Navarra (Spain), and the immunology samples will be analyzed at the Barcelona Institute for Global Health (ISGlobal), in Barcelona (Spain). Participants will be recruited by the investigators at the emergency room and/or COVID-19 area of the CUN. They will remain in the trial for a period of 28 days at their homes since they will be patients with mild disease. In the interest of public health and to contain transmission of infection, follow-up visits will be conducted in the participant's home by a clinical trial team comprising nursing and medical members. Home visits will assess clinical and laboratory parameters of the patients.

Intervention and comparator

Ivermectin will be administered to the treatment group at a 400μg/Kg dose (included in the EU approved label of Stromectol and Scabioral). The control group will receive placebo. There is no current data on the efficacy of ivermectin against the virus in vivo, therefore the use of placebo in the control group is ethically justified.

Main outcomes

Primary

Proportion of patients with a positive SARS-CoV-2 PCR from a nasopharyngeal swab at day 7 post-treatment.

Secondary

Mean viral load as determined by PCR cycle threshold (Ct) at baseline and on days 4, 7, 14, and 21.

Proportion of patients with fever and cough at days 4, 7, 14, and 21 as well as proportion of patients progressing to severe disease or death during the trial.

Proportion of patients with seroconversion at day 21.

Proportion of drug-related adverse events during the trial.

Median levels of IgG, IgM, IgA measured by Luminex, frequencies of innate and SARS-CoV-2-specific T cells assessed by flow cytometry, median levels of inflammatory and activation markers measured by Luminex and transcriptomics.

Median kinetics of IgG, IgM, IgA levels during the trial, until day 28.

Randomisation

Eligible patients will be allocated in a 1:1 ratio using a randomization list generated by the trial statistician using blocks of four to ensure balance between the groups. A study identification code with the format “SAINT-##” (##: from 01 to 24) will be generated using a sequence of random numbers so that the randomization number does not match the subject identifier. The sequence and code used will be kept in an encrypted file accessible only to the trial statistician. A physical copy will be kept in a locked cabinet at the CUN, accessible only to the person administering the drug who will not enrol or attend to patient care. A separate set of 24 envelopes for emergency unblinding will be kept in the study file.

Blinding (masking)

The clinical trial team and the patients will be blinded. The placebo will not be visibly identical, but it will be administered by staff not involved in the clinical care or participant follow up.

Numbers to be randomised (sample size)

The sample size is 24 patients: 12 participants will be randomised to the treatment group and 12 participants to the control group.

Trial Status

Current protocol version: 1.0 dated 16 of April 2020.

Recruitment is envisioned to begin by May 14th and end by June 14th.

Trial registration

EudraCT number: 2020-001474-29, registered April 1^st.

Clinicaltrials.gov: submitted, pending number

Full protocol

The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

Suppressive antibiotic therapy in prosthetic joint infections: a multicentre cohort study

OBJECTIVES

The aim was to describe the effectiveness of suppressive antibiotic treatment (SAT) in routine clinical practice when used in situations in which removal of a prosthetic implant is considered essential for the eradication of an infection, and it cannot be performed.

METHODS

This was a descriptive retrospective and multicentre cohort study of prosthetic joint infection (PJI) cases managed with SAT. SAT was considered to have failed if a fistula appeared or persisted, if debridement was necessary, if the prosthesis was removed due to persistence of the infection or if uncontrolled symptoms were present.

RESULTS

In total, 302 patients were analysed. Two hundred and three of these patients (67.2%) received monotherapy. The most commonly used drugs were tetracyclines (39.7% of patients) (120/302) and cotrimoxazole (35.4% of patients) (107/302). SAT was considered successful in 58.6% (177/302) of the patients (median time administered, 36.5 months; IQR 20.75-59.25). Infection was controlled in 50% of patients at 5 years according to Kaplan-Meier analysis. Resistance development was documented in 15 of 65 (23.1%) of the microbiologically documented cases. SAT failure was associated with age <70 years (sub-hazard ratio (SHR) 1.61, 95% CI 1.1-2.33), aetiology other than Gram-positive cocci (SHR 1.56, 95% CI 1.09-2.27) and location of the prosthesis in the upper limb (SHR 2.4, 95% CI 1.5-3.84). SAT suspension was necessary due to adverse effects in 17 of 302 patients (5.6%).

CONCLUSIONS

SAT offers acceptable results for patients with PJI when surgical treatment is not performed or when it fails to eradicate the infection.

Dissociation of neonatal and adult mice brain for simultaneous analysis of microglia, astrocytes and infiltrating lymphocytes by flow cytometry

•

Recovery of neural cells is higher with 30 % Percoll gradient than 30–70 %.

•

Papain enhances combined extraction of microglia, astrocytes and lymphocytes.

•

Dispase II potentiates papain action only in adult brain.

•

Mechanical dissociation isolates neonatal and adult astrocytes better than enzymes.

•

Papain + dispase II alows cell cytometry quantification of glial activation by LPS.

The technical difficulty to isolate microglia, astrocytes and infiltrating immune cells from mouse brain is nowadays a limiting factor in the study of neuroinflammation. Brain isolation requirements are cell-type and animal-age dependent, but current brain dissociation procedures are poorly standardized. This lack of comprehensive studies hampers the selection of optimized methodologies. Thus, we present here a comparative analysis of dissociation methods and Percoll-based separation to identify the most efficient procedure for the combined isolation of healthy microglia, astrocytes and infiltrated leukocytes; distinguishing neonatal and adult mouse brain. Gentle mechanical dissociation and DNase I incubation was supplemented with papain or collagenase II. Dispase II digestion was also used alone or in combination. In addition, cell separation efficiency of 30 % and 30–70 % Percoll gradients was compared. In these experiments, cell yield and integrity of freshly dissociated cells was measured by flow cytometry. We found that papain digestion in combination with dispase II followed by 30 % Percoll separation is the most balanced method to obtain a mixture of microglia, astrocytes and infiltrated immune cells; while addition of dispase II was not an advantage for neonatal brain. These dissociation conditions allowed flow cytometry detection of a slight glial activation triggered by sublethal LPS injection. In conclusion, the enzymes and Percoll density gradients tested here affected differently resting microglia, activated microglia/macrophages, astrocytes and infiltrated lymphocytes. Also, newborn and adult brain showed contrasting reactions to digestion. Our study highlights the strength of flow cytometry for the simultaneous analysis of neuroimmune cell populations once extraction is optimized.

Prevalence of eosinophilic esophagitis: A multicenter study on a pediatric population evaluated at thirty-six Latin American gastroenterology centers

INTRODUCTION AND OBJECTIVE

Eosinophilic esophagitis is a chronic, immune-mediated disease described in case series and publications worldwide. Over the past twenty years, the authors of different studies have attempted to evaluate its incidence and prevalence. The objetive of the present study was to estimate the prevalence of eosinophilic esophagitis in a group of children seen at 36 pediatric gastroenterology centers in ten Latin American countries.

MATERIALS AND METHODS

A multicenter, observational, and cross-sectional study was conducted that estimated the period prevalence of eosinophilic esophagitis in children seen at outpatient consultation and that underwent diagnostic upper gastrointestinal endoscopy for any indication at 36 centers in 10 Latin American countries, within a 3-month time frame.

RESULTS

Between April and June 2016, 108 cases of eosinophilic esophagitis were evaluated. Likewise, an average of 29,253 outpatient consultations and 4,152 diagnostic upper gastrointestinal endoscopies were carried out at the 36 participating centers. The period prevalence of eosinophilic esophagitis in the population studied (n=29,253) was 3.69 cases×1,000 (95% CI: 3.04 to 4.44), and among the children that underwent routine upper gastrointestinal endoscopy (n=4,152), it was 26x1,000 (95% CI: 22.6 to 29.4).

CONCLUSIONS

The general period prevalence of eosinophilic esophagitis in a group of children evaluated at 36 Latin American pediatric gastroenterology centers was 3.69×1,000, and in the children that underwent endoscopy, it was 26×1,000. There was important prevalence variability between the participating countries and centers. The present analysis is the first study conducted on the prevalence of pediatric eosinophilic esophagitis in Latin America.

A giant exoplanet orbiting a very-low-mass star challenges planet formation models

Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought.

Precocious pubertal events in Chilean children: ethnic disparities

PURPOSE

Puberty onset exhibits remarkable inter-individual and ethnic differences. 5% of Chileans are indigenous but puberty ethnic disparities have not been studied. We aim for evaluating precocious puberty prevalence in children with Mapuche ancestry vs non-indigenous Chilean children (according to their surnames).

METHODS

Longitudinal cohort study: 1003 children (50.2% girls) participating in the Growth and Obesity Chilean Cohort Study (GOCS) were studied. Annual anthropometry was measured since 4-7 years. Subsequently, Tanner staging and anthropometry were measured every 6 months. In girls, Tanner stage was assessed by breast palpation and in boys by testicular volume measurements. The cohort was stratified in three groups depending on Mapuche surname numbers as follows: (A) no indigenous surnames (n = 811), (B) one to two indigenous surnames (n = 147), and (C) three or more indigenous surnames (n = 45). We evaluated the prevalence of precocious thelarche, pubarche, menarche and gonadarche (testicular volume ≥ 4 ml-G2), using a cutoff age of 8 years in girls and 9 years in boys while controlling for socioeconomic status, body mass index, waist circumference, IGF-1 and DHEAS at 7 years.

RESULTS

In girls, no significant differences were observed. On the contrary, in boys, precocious gonadarche prevalence was higher in group C (29.2%) vs group A (6.0%) and vs group B (10.5%) (p =0.001, p = 0.004, respectively). Increased precocious gonadarche and pubarche risks in group C were observed even after adjustment [OR 7.31; 95% IC (2.32-23.51); p = 0.001] and [OR 6.17, 95% CI (1.62-23.49); p = 0.008], respectively.

CONCLUSION

Indigenous origin in Chile is an independent risk factor for precocious gonadarche and pubarche in boys but not in girls.

Randomized controlled trial of cognitive-motivational therapy program (PIPE) for the initial phase of schizophrenia: Maintenance of efficacy at 5-year follow up✰

AIM

The main goal of this study was to evaluate the effectiveness of a cognitive motivational treatment program.

METHOD

A randomized, controlled, single-blind clinical trial was carried out. A total of 104 patients were recruited to take part in the trial, of whom ultimately 62 patients were allocated into two groups and finished the study. An initial assessment was carried out before patients were randomly placed in one of two groups for the clinical trial: (a) PIPE program plus routine care; and (b) routine care only. Clinical assessments were performed at baseline at 6 months, 1 year and follow-ups, at 18 months and 5 years).

RESULTS

MANCOVA analysis of tests repeated 18 months after the start of the intervention detected significant differences between the two groups in terms of clinical variables, everyday functioning and relapses. These differences remained upon follow-up measurements taken five years after the start of the trial.

CONCLUSIONS

The present study offers scientific evidence for cognitive-motivational therapy's effectiveness as a treatment for clinical symptoms in the early stages of psychosis. PIPE intervention may contribute to long-term clinical improvement and stability.

Effect of milking frequency and α-tocopherol plus selenium supplementation on sheep milk lipid composition and oxidative stability

The aim of this research was to study the effect of milking frequency [once-daily milking (ODM) vs. twice-daily milking (TDM)] and antioxidant (AOX) supplementation on fatty acid (FA) profile and oxidative stability in sheep milk. Sixteen Assaf ewes were used; 8 did not receive any vitamin-mineral supplement (control), and the other 8 received an oral dose of 1,000 IU of α-tocopherol and 0.4 mg of Se daily. The experiment consisted of 2 consecutive periods; the first was 3 wk with TDM of both mammary glands. The second period was 8 wk and consisted of ODM of one mammary gland and TDM of the other gland. All ewes were fed ad libitum the same total mixed ration from lambing and throughout the experiment. There were no differences in plasma or milk Se concentrations between control and AOX ewes. However, plasma and milk α-tocopherol concentrations and AOX capacity were increased in ewes receiving the AOX supplement. Milk FA profile was practically unaffected after 21 d of AOX supplementation. However, after 77 d, AOX supplementation increased the relative percentage of C16:0 and cis-9 C18:1 and reduced the proportions of some saturated FA with less than 16 carbons and cis-9 C12:1. Antioxidant supplementation had no effect on the proportions of conjugated linoleic acid or total polyunsaturated FA (PUFA) but decreased the proportion of trans-7,cis-9 C18:2 and increased that of n-6 C20:3. Once-daily milking did not affect α-tocopherol, Se, or fat resistance to oxidation in milk. Total monounsaturated FA, cis-9 C16:1, and several cis and trans isomers of C18:1 were increased and total saturated FA were decreased in milk from ODM glands. Compared with TDM, ODM increased the proportions of cis-9,cis-12 C18:2 and several isomers of C18:2 and reduced those of cis-9,cis-12,cis-15 C18:3 and some PUFA of 20 and 22 carbons, but total proportion of PUFA was unaffected. Once-daily milking and AOX supplementation modified milk FA profile, but the effects of ODM could be considered of little biological relevance for consumer health. Supplementing ewes with α-tocopherol plus Se could be considered an effective strategy to improve plasma AOX status and reduce milk fat oxidation without substantial changes in the milk FA profile.

QTL mapping of melon fruit quality traits using a high-density GBS-based genetic map

BACKGROUND

Melon shows a broad diversity in fruit morphology and quality, which is still underexploited in breeding programs. The knowledge of the genetic basis of fruit quality traits is important for identifying new alleles that may be introduced in elite material by highly efficient molecular breeding tools.

RESULTS

In order to identify QTLs controlling fruit quality, a recombinant inbred line population was developed using two commercial cultivars as parental lines: "Védrantais", from the cantalupensis group, and "Piel de Sapo", from the inodorus group. Both have desirable quality traits for the market, but their fruits differ in traits such as rind and flesh color, sugar content, ripening behavior, size and shape. We used a genotyping-by-sequencing strategy to construct a dense genetic map, which included around five thousand variants distributed in 824 bins. The RIL population was phenotyped for quality and morphology traits, and we mapped 33 stable QTLs involved in sugar and carotenoid content, fruit and seed morphology and major loci controlling external color of immature fruit and mottled rind. The median confidence interval of the QTLs was 942 kb, suggesting that the high density of the genetic map helped in increasing the mapping resolution. Some of these intervals contained less than a hundred annotated genes, and an integrative strategy combining gene expression and resequencing data enabled identification of candidate genes for some of these traits.

CONCLUSION

Several QTLs controlling fruit quality traits in melon were identified and delimited to narrow genomic intervals, using a RIL population and a GBS-based genetic map.

Comparing genetic diversity and demographic history in co-distributed wild South American camelids

Vicuñas and guanacos are two species of wild South American camelids that are key ruminants in the ecosystems where they occur. Although closely related, these species feature differing ecologies and life history characters, which are expected to influence both their genetic diversity and population differentiation at different spatial scales. Here, using mitochondrial and microsatellite genetic markers, we show that vicuña display lower genetic diversity within populations than guanaco but exhibit more structure across their Peruvian range, which may reflect a combination of natural genetic differentiation linked to geographic isolation and recent anthropogenic population declines. Coalescent-based demographic analyses indicate that both species have passed through a strong bottleneck, reducing their effective population sizes from over 20,000 to less than 1000 individuals. For vicuña, this bottleneck is inferred to have taken place ~3300 years ago, but to have occurred more recently for guanaco at ~2000 years ago. These inferred dates are considerably later than the onset of domestication (when the alpaca was domesticated from the vicuña while the llama was domesticated from the guanaco), coinciding instead with a major human population expansion following the mid-Holocene cold period. As importantly, they imply earlier declines than the well-documented Spanish conquest, where major mass mortality events were recorded for Andean human and camelid populations. We argue that underlying species' differences and recent demographic perturbations have influenced genetic diversity in modern vicuña and guanaco populations, and these processes should be carefully evaluated in the development and implementation of management strategies for these important genetic resources.

[Risk of falls and consumption of medicines in an elderly population]

OBJECTIVES

To describe the risk factors and the effect of medication use on the risk of falls in a population of 65 years or older.

MATERIAL AND METHODS

Descriptive study of falls in the elderly population. The risk factors and consequences of the fall were recorded. Hypnotic and sedative risk drugs, opioids, and the simultaneous consumption of six or more drugs were considered. Diuretics were also included. The cumulative incidence for each group and the corresponding relative risks of falls were analysed from the cases registered between June and November 2016.

RESULTS

During the study period, 60 falls were reported, of which 66% were by women and 34% by men. The cumulative incidence of falls was 3 per thousand women (95% CI: 2.22-4.08), and 2 per thousand men (95% CI: 1.44-3.41). The majority (71%) had consumed risk medication. Six or more medications were taken by 40% of the men and 62.5% of the women, and 97.6% was risk medication. The relative risk of falls in people using hypnotics, sedatives and opioids compared to non-users was 8.7 in men and 7.1 in women. In people who took diuretics, the relative risk was 4.6 for both genders. In women on multiple medications the relative risk was 3.7 compared to 1.7 in men.

CONCLUSIONS

Polypharmacy and the use of hypnotic and sedative drugs and opioids and diuretics are an important public health problem, due to being risk factors for falls in this population, with a greater impact for women.

Caffeine-mediated BDNF release regulates long-term synaptic plasticity through activation of IRS2 signaling

Caffeine has cognitive‐enhancing properties with effects on learning and memory, concentration, arousal and mood. These effects imply changes at circuital and synaptic level, but the mechanism by which caffeine modifies synaptic plasticity remains elusive. Here we report that caffeine, at concentrations representing moderate to high levels of consumption in humans, induces an NMDA receptor‐independent form of LTP (_CAFLTP) in the CA1 region of the hippocampus by promoting calcium‐dependent secretion of BDNF, which subsequently activates TrkB‐mediated signaling required for the expression of _CAFLTP. Our data include the novel observation that insulin receptor substrate 2 (IRS2) is phosphorylated during induction of _CAFLTP, a process that requires cytosolic free Ca²⁺. Consistent with the involvement of IRS2 signals in caffeine‐mediated synaptic plasticity, phosphorylation of Akt (Ser473) in response to LTP induction is defective in Irs2^−/− mice, demonstrating that these plasticity changes are associated with downstream targets of the phosphoinositide 3‐kinase (PI3K) pathway. These findings indicate that TrkB‐IRS2 signals are essential for activation of PI3K during the induction of LTP by caffeine.

Absence of Notch1 in murine myeloid cells attenuates the development of experimental autoimmune encephalomyelitis by affecting Th1 and Th17 priming

Inhibition of Notch signalling in T cells attenuates the development of experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Growing evidence indicates that myeloid cells are also key players in autoimmune processes. Thus, the present study evaluates the role of the Notch1 receptor in myeloid cells on the progression of myelin oligodendrocyte glycoprotein (MOG)_35-55 -induced EAE, using mice with a myeloid-specific deletion of the Notch1 gene (MyeNotch1KO). We found that EAE progression was less severe in the absence of Notch1 in myeloid cells. Thus, histopathological analysis revealed reduced pathology in the spinal cord of MyeNotch1KO mice, with decreased microglia/astrocyte activation, demyelination and infiltration of CD4⁺ T cells. Moreover, these mice showed lower Th1 and Th17 cell infiltration and expression of IFN-γ and IL-17 mRNA in the spinal cord. Accordingly, splenocytes from MyeNotch1KO mice reactivated in vitro presented reduced Th1 and Th17 activation, and lower expression of IL-12, IL-23, TNF-α, IL-6, and CD86. Moreover, reactivated wild-type splenocytes showed increased Notch1 expression, arguing for a specific involvement of this receptor in autoimmune T cell activation in secondary lymphoid tissues. In summary, our results reveal a key role of the Notch1 receptor in myeloid cells for the initiation and progression of EAE.

Ovine Toxoplasmosis: A New Look at its Pathogenesis

Conditions causing reproductive failure are a significant concern in the livestock industry, and amongst these, ovine toxoplasmosis is one of the most important. Despite decades of research, there remain gaps in knowledge about this disease, especially regarding the pathogenesis of abortion in sheep. As for other diseases causing ovine abortion, such as chlamydial abortion or border disease, the consequences of infection with Toxoplasma gondii depend largely on the stage of gestation, but the mechanisms involved are not well understood. Immunological modulation occurring during gestation has been proposed as the main mechanism accounting for this clinical variation. However, the extent and effect of such modulation has not yet been identified clearly in sheep and the involvement of other unknown factors has been proposed. Recent experimental studies have defined an unacknowledged clinical presentation of ovine toxoplasmosis, where abortions occur during the acute phase of infection, resulting in as high as 100% fetal loss in susceptible sheep. The pathogenesis of this clinical form differs from that of classically described ovine toxoplasmosis, and its pathological features resemble those of the perinatal syndrome known as cerebral palsy in man. A range of variables, including individual susceptibility, isolate virulence and infective dose, have been proposed as key factors in the development of one or the other of these clinical forms and warrants further investigation in this important disease.

Early postpartum administration of equine chorionic gonadotropin to dairy cows calved during the hot season: Effects on fertility after first artificial insemination

Heat stress reduces fertility of high-producing dairy cows, and early administration of equine chorionic gonadotropin (eCG) may improve it. Here, 401 heat-stressed, high-producing dairy cows on a single commercial farm were given eCG (500 UI, n = 214) or saline (n = 187) on days 11-17 after calving, and the effects on fertility after the first artificial insemination (AI) were assessed. On post-partum day 96.34 ± 9.88, all cows were inseminated after a "double short Cosynch" synchronization protocol. Ovarian activity and uterine status were checked by ultrasound on the day of eCG administration and every 7 days thereafter for a total of 3 weeks; checks were also performed during synchronization, and 7 days after AI. On post-partum day 30, cytobrush uterine cytology was performed to check for subclinical endometritis. Pregnancy status was checked on days 30 and 60 after AI. The eCG and control groups did not differ significantly in terms of average lactations per cow (2.33 ± 1.34), days in milk at first AI (96.33 ± 9.88), average milk yield at AI (41.38 ± 7.74 L), or the particular inseminator or bull used for AI. The eCG and control groups showed increasing ovarian activity with time, with approximately 75% of cows in both groups showing a corpus luteum at the beginning of the synchronization protocol. On post-partum day 30, 17.4% of eCG cows and 22.9% of control cows showed subclinical endometritis. Cows treated with eCG showed a tendency toward lower hyperecogenic intraluminal content (16.8 vs. 21.4%, P = 0.15), but ovarian activity during the synchronization protocol was similar between eCG and control groups, with 91% of animals in both groups showing luteolysis after prostaglandin application and 88% showing ovulation after the last administration of gonadotropin-releasing hormone. Fertility was similar between the two groups at both time points after AI (30 days, 34.9 vs. 31.8%; 60 days, 30.6 vs. 28.5%; P > 0.2). These results suggest that early postpartum eCG administration does not improve fertility of heat-stressed dairy cows as long as 60 days after AI. Other strategies may be more effective at mitigating the ability of post-partum heat stress to reduce fertility of high-producing dairy cows.

Effects of a silver nanomaterial on cellular organelles and time course of oxidative stress in a fish cell line (PLHC-1)

Among the nanomaterials currently in commercial products, those based on silver are the most used, and so there is a high probability that silver nanoparticles (AgNPs) will be released into aquatic environments where they could adversely affect aquatic organisms, including fish. Taking this into account, the aim of the present work was to characterize in depth the mechanisms underlying the toxic action of AgNPs using fish cell lines, determining specifically the contribution of alterations in cellular structures and oxidative stress time course to the cytotoxicity of AgNPs. Since liver plays a key role in detoxification, the hepatoma cell line PLHC-1 was used. Exposure to AgNPs (NM-300K, obtained from the Joint Research Centre Repository) caused alterations at the lysosomal and mitochondrial levels at lower concentrations than those that disrupted plasma membrane (evaluated by means of neutral red, alamarBlue, and 5-carboxyfluorescein diacetate, acetoxymethyl ester assays respectively). AgNO₃, used as a control Ag⁺ ion source, produced similar cytotoxic effects but at lower concentrations than AgNPs. Both silver forms caused oxidative disruption but the initial response was delayed in AgNPs until 6h of exposure. Transmission electron microscopy analysis also evidenced the disruption of mitochondrial structures in cells exposed to cytotoxic concentrations of both forms of silver. At non-cytotoxic concentrations, AgNPs were detected inside the nucleoli and mitochondria, thereby pointing to long-term effects. The present work evidences the mutual interaction between the induction of oxidative stress and the alterations of cellular structures, particularly mitochondria, as cytotoxicity mechanisms not exclusively associated to NPs.